FR2504894A1 - COHERENT ENVELOPE ARTICLE AND METHOD FOR MANUFACTURING THE SAME - Google Patents

Abstract

A flexible, tubular food covering made of cellulose is gathered and compressed on a fixed tubular core, a covering bar being produced due to the high compression, which bar has an additional filling length, an improved structural strength and is suitable for larger filling funnels.

Description

 The invention relates to cellulosic casings or skins for food products, and more particularly to pleated cellulosic casings for foodstuffs, mounted compactly on hollow and rigid tubular cores, in a highly compressed form so as to constitute pleated casing sticks. which, compared to what was possible to date, offer a considerably increased packing length have a more stable and resistant structure and have the additional feature of allowing the adaptation of envelopes or skins, currently available in the trade in given dimensions, for use on tamping mandrels with larger cross section.The invention is particularly applicable to the production of articles consisting of shirred casing sticks, used in the food industry for the production of sausages of all sizes, and it also presents important advantages when it is used for placing or stuffing into pieces of casing food products in the form of pieces such as pieces of whole-bone meat.

 Envelopes or artificial skins for food products, used throughout the world in the treatment of a wide variety of meat and other food products, for example sausages of various types, cheese rolls, turkey roasts and the like are commonly prepared from regenerated cellulose and other cellulosic materials. Envelopes exist in several different types and sizes to suit the different categories of food products to be prepared and are available in reinforced or unreinforced form, the reinforced envelopes, commonly called "fibrous envelopes", comprising a fibrous web reinforcement embedded in their wall.

 A common feature of many processed products, particularly meat products, is that the mixture of edible ingredients, commonly referred to as "emulsion", is introduced or stuffed into a pressurized casing and the processing of the food product takes place. performs after it has been placed in the envelope.

The food product can also be stored and transported while wrapped, although in many cases and particularly in the case of small sausages such as Frankfurt sausages, the casing is removed from the food product at the end. treatment.

 The term "small food casings" refers generally to the casings used for the preparation of small sausages such as sausages of Frankfurt. As this expression suggests, this type of envelope for food products has, in the packed state, a small diameter, the diameter in the expanded state generally ranging between about 13 and about 40 mm, and this envelope is the more generally provided in the form of unreinforced thin-walled tubes of very great length. For ease of handling, these envelopes, which may be 20 to 50 meters in length or longer, are pleated and compressed to form what are commonly referred to as "shirred envelope sticks" of about 20 to 60 cm. US Pat. Nos. 2,983,949 and 2,984,574, among others, describe pleating machines and the products they give.

 Envelopes for large food products ", this term denoting envelopes used for the preparation of relatively large food products such as salamis and mortadellae, meatloaf, heels of cooked and smoked hams, and the like are produced in the stuffed state with diameters of about 40 to 200 mm or more, generally having a wall about three times thicker than that of "small envelopes" and having a fibrous reinforcement ply embedded in their wall, although they can be prepared without this reinforcing element.

For many years, large tubular casings have been provided to flattened food processing companies, cut to predetermined lengths of about 0.6 to 2.2 m. However, more recently, but prior to the present invention, both fibrous and non-reinforced type large envelopes have been and still are provided in the form of pleated sticks comprising up to about 65 m. Envelopes to be stuffed by means of apparatus working at high speed.

 When preparing and using artificial skins or skins for food products, it is very important to control the moisture content of the envelopes. Although pleated cellulosic casing sticks of the type used in the invention must have a moisture content of at least about 13% of the total weight of the casing, the moisture content may be higher.

 When small regenerated cellulose casings are produced, it is generally preferable that their water content be between about 14% and 18% of the total weight of the casing to allow tamping operations to be performed without deterioration of the casing. envelope. This relatively narrow range of moisture content is also important, as excessive envelope breaks have occurred during tamping at lower moisture levels, and higher moisture levels have the effect of conferring excessive plasticity to the material. envelope and, therefore, cause excessive jamming.

Envelopes of large dimensions as described above have recently been improved since sections of pleated and compressed envelope are available in the pre-moistened state so that the long operation has now been eliminated. and difficult to imbibe these envelopes immediately before the stuffing operation. Moisture content of larger envelopes, of the fibrous reinforcement type, furnishes
in the pleated and pre-moistened state, generally appear to be between about 16% and 35% of the total weight of the envelope.

 The particular moisture content may be selected to suit the requirements or preferences of the user. If the moisture content is high and a long period of storage is expected before filling, it is advisable to take measures to prevent the growth of mold or bacteria. A method according to the invention is to limit the activity of the added water before or during the stuffing by means of sufficient amounts of solutes such as propylene glycol or glycerin. These materials also perform useful functions of plasticizers or humectants in envelopes to be creased and compressed.

 The enveloping pleating techniques described above with reference to the aforementioned patents, as well as in other patents, can be generally described as continuously advancing a flat food jacket section, for example from a coil, in order to introduce it into a pleating machine where it is inflated with a low-pressure gas, usually air. The inflated envelope is passed through a group of pleating rolls which fold against a retainer mounted on the mandrel or around the pleating mandrel until the predetermined pleated length is obtained. In the case of a floating mandrel type pleating machine, as described, for example, in U.S. Patent No. 3,766,603, the pleated casing is then transferred linearly beyond or to the the gap between the retaining element against which the pleating has been made and on an extension of the mandrel where it is compressed to form a stick of desired length. In the case of a shrink mandrel pleating machine, as described, for example, in U.S. Patent No. 2,583,654, the pleating mandrel, on which the pleated casing remains, is rotated. to another position in which the pleated envelope is compressed to form the stick of desired length.

 Normal compression provides a stick whose length can range from about 1.0% to about 1.2 or 1.3% of the initial length of the envelope.

 U.S. Patent No. 2,001,461, for example, describes how an envelope of initial length of 1006 cm is reduced to a length of less than 10 cm in the form of a stick. It is further indicated in the aforementioned patent that the lower practical limit at which it is probably possible to lower the ratio of the length of the stick to the length of the initial envelope is in the vicinity of a hundred and thirtieth (1/130 ). However, the above-mentioned patent does not recognize the problems encountered in attempting to produce such a stick made of a pleated and highly compressed envelope of commercially practical length, and it ignores the importance of the size of the opening of the envelope.

 In industry, up to now, the ratios of the initial length of the envelope to the length of the pleated stick have generally been in the range of 70 to 100.

Such a ratio is referred to as "compression ratio" or "reduction ratio" and is the reverse of the ratio described in the aforementioned Patent No. 2,001,461.

où PE = Rendement de compression
Lc = Longueur d'enveloppe
Ls = longueur du bâton d'enveloppe plissée
FW = largeur à plat de l'enveloppe
t c = épaisseur de la paroi de l'enveloppe
OD = diamètre extérieur du bâton d'enveloppe plissée
ID = diamètre intérieur du bâton d'enveloppe plissée.The compression yield is another means of quantitatively expressing the amplitude of the compression of the initial envelope lengths to form the pleated stick. The compression yield is defined as the ratio of the volume of the pleated and compressed envelope, of unit length, to the volume that would be occupied by the full envelope of the same unit length, and it can be determined by the following relationship

where PE = compression efficiency
Lc = Length of envelope
Ls = length of pleated casing stick
FW = flat width of the envelope
tc = wall thickness of the envelope
OD = outer diameter of pleated casing stick
ID = inside diameter of the folded envelope stick.

 This calculation automatically takes into account the density and / or the density of the material itself of the envelope. An examination of the relation shows that the ratio is in fact the volume occupied by the flat envelope in the pleated envelope stick, divided by the volume of a hollow cylinder having the same dimensions as the folded envelope stick. The importance of increasing the efficiency of compression is therefore measured by its approximation of one (1), namely unity.

Since the compression ratio is the ratio Lc to L5, another way to express the compression efficiency is given by the following relationship
PE = (compression ratio)

<tb> 2 <SEP> x <SEP> FW <SEP> x <SEP> tc
<tb><SEP>#<SEP>#
<tb># / 4 <SEP> (OD2 <SEP><SEP> - <SEP> ID2)
<Tb>
It can be seen that for a given compression yield, the compression ratio varies with the difference between the outer diameter and the inside diameter of the rod of a given dimension envelope. Moreover, since the outside diameter is necessarily limited by the flat width (FW) of the envelope used to form the stick, an increase in the diameter difference to increase the compression ratio must ultimately decrease the size of the opening or the inside diameter. Although the goals of maximum stick openness and maximum compression ratio are antagonistic, it remains the fact that the compression efficiency is maximized at a given compression ratio when the inside diameter of the stick is maximized.

 it is generally desirable to use the stuffing mandrel having a bore of maximum dimension (maximum internal section) with a given size envelope, in part to maximize the production rate and minimize the stuffing pressure. Another reason for using a maximum size mandrel is the elimination of the risk of "degreasing". Degreasing is a phenomenon that occurs when the meat emulsion passes through a stuffing mandrel at a shear rate high enough to cause decomposition of the emulsion and allow water and grease to separate. Water and fat then accumulate between the surface of the finished sausage and the cellulosic food casing during treatment, resulting in an unsatisfactory sausage having an unacceptable visual appearance. The shear rate decreases when the internal diameter of the sausage is reduced. stuffing mandrel increases.

 The goals sought in the pleating technology are to produce an envelope stick that can be unfolded and stuffed on a tamping machine, continuously, without mechanical defects or breakdowns, to ensure continuous production, the stick itself. even having a structural and mechanical integrity, that is to say a coherence, sufficient to withstand the loads to which it is normally subjected during packaging, storage, handling and placement on the stuffing apparatus, and it is further desired to compress, in a stick of given length, a stuffing envelope as long as is technically possible to use it on a stuffing mandrel whose channel is as large as possible.

 Therefore, the "ideal" envelope stick is a high coherence stick, associating a long envelope length per unit length of stick (high compression ratio) with a large inside diameter or a large dimension of opening (high compression yield).

 U.S. Patent No. 3,528,825 discloses prior means for calculating ratio and compression efficiency. The description, from line 75 of column 5 to line 5 of column 6, relates to a pleated casing stick in which a casing 30 m in length has an outside diameter in the inflated state of 1 , 75 cm for a wall thickness of 0.0254 mm. This envelope is folded to form a stick having an outer diameter of 2.22 cm, an inner diameter of 1.27 cm and a length of 41.28 cm.

With the aid of these data and the previous formula giving the compression yield, it has been found that the envelope of the prior art, described in the aforementioned patent No. 3,528,825, has a compression yield of 0.374.

The compression ratio of this anterior envelope is 70, namely a length of 30 m reduced to 41.28 cm by pleating and compression.

 The coherence of a pleated casing stick is determined by the measurement of the bending moment, in N.cm at the moment of the rupture of a stick. An envelope stick is keyed on two V-notch brackets, fixed on a base plate and spaced apart by a distance (D) equal to about 80 to 90 * of the length of the tested shell stick. A pressure element, having V-notched spacers spaced apart by a distance D - 10 cm, is lowered centrally on the top of the envelope stick.

Downward pressure is exerted using a hand-operated handle, rack-and-pinion linkage on a dynamometer (such as the Model Hunter Force Meter).
L-IM "with a" maximum holding device ") which is fixed centrally on the pressure element An increasing force is applied until the rupture of the casing stick The force P indicated in newtons is noted.

The bending moment, in newton-centimeters at the moment of rupture occurring on the apparatus is equal to
P / 2 x 5 cm and, consequently, the displayed force P is equal to the value, in N.cm, of the bending moment breaking the envelope stick. In general, a coherence of at least about 14 Ncm is required, and a coherence of at least about 28.25 Ncm is particularly suitable and preferred.

 Since the relationship between the effective diameter of the aperture of the envelope stick and the diameter of the stuffing mandrel is a most significant measure of the operability of the envelope article, a test was devised. fall adjustment "to which pleated envelope articles are subjected. To simulate the placing of a pleated stick on a stuffing mandrel and thus to measure the useful internal diameter of the pleated stick, an attempt has been made in which a pleated stick is placed on the upper end of a vertical rod. stainless steel, longer than the pleated stick, and then let the stick fall freely under the effect of its own weight, around the stem, to its lower end. In particular, the rod can be arranged vertically on a table. The pleated stick is placed on the upper end of the rod, then released. If the stick falls to the surface of the table, the fall fit test is satisfactory. There is a set of rods whose diameters increase from 0.254 to 0.254 mm and, for some plagies of dimensions of envelopes, rods have been made whose diameters increase in steps of 0.051 mm.

The pleated stick is tested on each stem, starting from the smallest stem and passing over stems of increasing size until it can no longer fall freely along the entire length of the stem. The larger diameter rod on which the stick freely falls along its entire length indicates the useful internal diameter of the pleated stick, ie the "fall-in" diameter.

In the manufacture of sticks consisting of a pleated cellulosic envelope, the size of the opening varies slightly from one stick to the other, partly as a result of the irregularities presented by the projections of the folds inside the opening of the stick. For this reason, in tests, it is necessary to subject several pleated sticks, for example at least about 10 sticks, to a measurement for the falling fit, and the arithmetic mean is used to determine the functional character of the entire group with respect to the adjustment on the stuffing mandrel. As indicated previously, the averages of the fall adjustment are preferably calculated with an accuracy of 0.025 mm, and a requested drop adjustment is defined with this degree of precision. For example, if the requested value is at least 12.446 mm , an average fall adjustment of 12.4206 mm would be unacceptable, cardboard large number of sticks of the group represented by the average measure of fall adjustment of 12.4206 mm does not
would not be functional on a 12.446 mm diameter stuffing mandrel.

 One of the most important factors in the pleating of a small-size food casing is the quality of consistency, i.e., the stability of the pleated stick as a self-supporting article. The consistency of the stick is particularly important when determining the ability of such sticks to be used with automatic food stuffing equipment, for example the machine used for the preparation of products such as Frankfurters and sausages. other similar food items. A gap or a cut in a pleated stick before mounting it on a stuffing mandrel makes the stick unsuitable for use on such automatic stuffing equipment.

Therefore, any treatment of the tubular food casing, which can be put in the form of a pleated casing stick, should not affect the consistency of the stick, but should instead tend to increase it.

 Significant efforts have recently been made in the food casing or skins industry, particularly small envelopes, on the development of systems for producing highly coherent envelope sticks. These efforts include, inter alia, chemical treatments such as that described, for example, in U.S. Patent No. 4,137,947.

 Conventional pleating on modern pleating machines results in pleated casing sticks having a visible angular offset between a plane perpendicular to the longitudinal axis of the staff and a plane in which a fold is formed. This offset is called the angle of the fold.

A conventional pleated stick, devoid of the core element according to the invention, and having a crease angle of this nature has a coherence and structural integrity substantially higher than those of a stick of the same type which has been pleated with so that the folds are perpendicular to the longitudinal axis of the stick, because the overall length of the stick is substantially equal to that of a stack of cones nested in one another and interconnected.

 In particular, it has been found that, when a package of weaker sizes used for the manufacture of Frankfurter type products, when a conventional pleated stick (without a core) is strongly compressed so that its compression ratio is maximized, the consistency or the structural integrity of the compressed stick deteriorates to the point of rendering the stick unusable.

In other words, the stick is made fragile, easily breaks and can not be mounted on a stuffing mandrel.

This effect is believed to occur when significant longitudinal compressive forces tend to flatten the geometry of the "nested cones" produced during the pleating operation.

 It has now been found that when a tubular casing is subjected to the pleating operation (that is, transformed from a flattened tubular shape to a pleated and compressed form as a stick, as previously described), it appears in the stick pleated resulting from large forces, exerted radially inward, when high compression yields are obtained.

The magnitude of these large forces was not known before strongly compressing pleated casing sticks on core members according to the invention, and it was found that substantially rigid cores would be subject to some loss. of diameter with time. It has been known until now that the inside diameter of conventional pleated rods (without tubular core) decreased abruptly by retracting (unloading) the pleating mandrel immediately after compression, and that a more gradual additional reduction seemed to continue for about a week or more after removal of the mandrel, the amplitude of the forces causing this loss of diameter not being recognized in the prior art.

It has furthermore been found that the amplitude of these radially inwardly oriented forces is proportional to the longitudinal compressive force used to compress the stick to the initial compressed length that the stick has immediately before being discharged from the mandrel. . In other words, the forces exerted radially inward increase with the longitudinal compressive force.

 British Patent No. 1,167,377 discloses a stick consisting of a pleated tubular casing which is carried by a hollow caliber (core) configured and dimensioned to fit around a stuffing mandrel. It is stated in the aforementioned patent that a friction fit is made inside the stick to prevent decompression or sliding of the latter out of the caliber. It is indicated that the caliber may be made of any desired material, for example synthetic plastic material or thin cardboard. According to a particular embodiment of the caliber described in the aforementioned patent, this gauge is made of extruded polyvinyl chloride to form a cylinder whose wall has a thickness of about 0.25 mm. The article described in the aforementioned patent was marketed in the form of a polyvinylidene chloride tubular sheet, pleated on a cellulose acetate core with an internal diameter of 25 mm and a wall thickness of 25 mm. about 0.292 mm.

The object of the invention described in the aforementioned British patent has never been used with a pleated cellulosic tubular casing.

 In addition to the above use, the use of a hollow core or a central ube, as a support for large pleated envelopes, has been known for many years. All applications, known until now, the concept of a soul with pleated cellulosic envelopes, however, were intended to ensure the integrity and prevent the increase in size during imbibition. Small-sized rods were used for transportation and handling prior to the development of coherent shell sticks. The pleated envelope was slid off the stems so as to pass over the stuffing mandrels during use.

 In recent years, the technique of cellulosic food envelopes has shifted away from the use of inner tubes for holding and supporting the envelopes towards external support and support means such as nets or shrink films. or elastic in the case of envelopes of intermediate dimensions and large dimensions. The envelopes of small dimensions are used in the form of coherent sticks without any other means of support.

 The main object of the invention is a pleated casing article of high coherence, comprising a pleated casing compressed at a compression ratio greater than that which it was possible to obtain in practice in this field, while retaining an acceptable aperture size, as evidenced by high compression efficiency.

 Another object of the invention is a high consistency pleated casing article having a high compression ratio and efficiency, and also having a general structure and type which are generally suitable for the entire range of dimensions. and types of envelopes used in the food industry.

 Another important object of the invention is a high density pleated casing article having a compression ratio associated with a compression efficiency which are both significantly greater than those obtainable with the casings produced until this time. day, together with all the problems that may arise in the prior art due to lack of integrity of the structure or lack of coherence are eliminated.

Another important object of the invention is a high density pleated casing article having a core which has suitable physical properties to oppose the large forces exerted radially inward when a tubular casing is subjected to the pleating operation, then compressed to a high compression ratio.

 Another subject of the invention is a method of manufacturing high density pleated casing stick articles comprising a core, this method making it possible to manufacture these articles on pleating machines currently available at the price, if necessary, only slight modifications to produce the article according to the invention.

 Another object of the invention is an article having an envelope having both a larger opening and a higher compression ratio than can be obtained with a product without a core.

 Another important object of the invention is a high density pleated casing article having a core and with which standardized and particular casing dimensions, taken in all envelope size ranges, can be fitted to mandrels. respectively larger than those used until now. The improvement provided by the pleated envelope article according to the invention to the technology thus relates to greater efficiency of the stuffing of food articles of all types in available envelopes.

 A particular object of the invention is a high density pleated casing stick article having a core which replaces the mandrel of the stuffing machine and therefore constitutes a consumable member of the stuffing machine.

 A further particular object of the invention is a high density pleated casing stick article whose core may be selectively used as a support tube for sliding on a stuffing mandrel of a stuffing machine or alternatively, as a stuffing mandrel proper, a calibrating member of one type or another being mounted on the core of the article and disposed within an unfolded section of the pleated envelope .

 It appeared, according to the invention, a new use for souls, different from that of the prior art and that the souls are intended to reduce the effects of the force exerted radially inward on the envelope pleated to such an extent that not only compression ratios substantially higher than those obtained in the prior art (coreless pleated sticks, compressed and pleated under the same conditions) are obtained, but that these higher compression ratios can be obtained with articles with envelopes having usable opening dimensions equivalent to or even greater than those available with comparable pleated staples without the aforesaid cores. This is contrary to the expectations of those skilled in the art, that is, to the forecasts which considered that a soul would occupy space and thus reduce the useful opening of the envelope stick. Therefore, it was anticipated that a soul would have a negative effect on the compression ratio. Contrary to this prediction, the high density cellulosic casing article and core according to the invention can have a substantially higher compression ratio, without decreasing the usable aperture size, and thus a stick article can be obtained. pleated and soul having a higher compression performance than a pleated club without soul. Another feature of the article according to the invention is that it has improved structural integrity and strength.

 In one embodiment that is particularly useful with a stuffing apparatus for packaging pieces of meat, such as hams without whole bones and the like, the core itself of the article according to the invention is used at the same time. place a stuffing mandrel.

It should be noted, however, in this regard that the stuffing apparatus for hams without whole bones is considered to be an object distinct from that of the invention which in this case only relates to the adaptation to a such apparatus of the concept of the pleated stick with high density and soul. It should also be noted that such apparatus is the subject of US Patent Application No. 261,313.

 Another embodiment of the invention includes a high density pleated casing article and Sme, which may be used selectively as a support tube for sliding on a stuffing mandrel of a stuffing apparatus. alternatively, as a stuffing mandrel proper, comprising a calibrating element of one type or another, mounted on the core of the article and disposed within an unfolded section of the article. pleated envelope. It should be noted, however, that such a pleated envelope article is the subject of United States Patent Application No. 273,180.

 In general, the invention relates to the combination of a tubular core and a cellulosic food casing section wetted in a predetermined manner, having a moisture content of at least 13% of the total weight of the casing. envelope, this envelope section being pleated and strongly compressed on the core, at a high compression ratio and at a compression efficiency not falling below about 0.50, the ratio and the compression efficiency being also and respectively greater than those obtained with the same envelope length, pleated and strongly compressed, under the same conditions of pleating and compression, but without a core, thus generating a large expansion force oriented towards the inside of Another feature of the invention is that the core is rigid enough to withstand the deformations and size reductions of its opening under the effect of the large force of expansions. ion exerting inwards. By way of comparison between pleated and soul-compressed and soulless envelopes, it may be noted that the coreless envelope article does not have an outer longitudinal retaining element.

 The term "same pleating and compression conditions" as used herein means that the pleating method and apparatus (e.g. pleating means and pleating mandrel diameter) and method, apparatus and the length in the compressed state or the final compressive force, are essentially the same.

 In a preferred preferred form of the invention, the compression yield is maintained at 0.60 and above.

 In a preferred embodiment of this coherent envelope article, based on a comparison of fall adjustments (as described in more detail above), the core has an interior opening of at least as large a size as would be the inner opening of the same envelope folded and strongly compressed, under the same conditions of pleating and compression, but without soul. In a preferred embodiment, the casing is of the unreinforced cellulose type, of small size, having a diameter in the inflated state of less than about 40 mm, and is compressed at a compression ratio of at least 100. .

 The invention also relates to a method of manufacturing a pleated and highly compressed envelope article comprising a core, said method comprising the steps of: (a) producing a cellulosic food casing section having a moisture content of at least about 13% of the total weight of the casing (b) to slide the inner circumferential surface of the cellulosic food casing section onto a first end of a mandrel having an end portion of reduced diameter at its second end; (c) pleating the envelope section on the mandrel; (d) disposing a hollow core coaxially and contiguously to the end portion of reduced diameter of the mandrel, said core being rigid enough to withstand the deformation and decrease of the dimension of its opening under the effect of a force expansion exerted into the interior of the envelope as a result of the compression of the envelope; (e) linearly moving the pleated casing section along the mandrel to bring it to the outer surface of the coaxially disposed core; and (f) compressing the pleated casing section on the web to a high compression ratio and a high compression efficiency to produce said inwardly extending envelope expansion force.

 An alternative of the invention is a method of manufacturing a pleated and highly compressed envelope article comprising a core, which method comprises the steps of: (a) using. a cellulosic food casing section having a moisture content of at least about 13% of the total weight of the casing (b) to slide the inner circumferential surface of the cellulosic food casing section to a first end of a mandrel; (c) pleating and compressing said jacket section on the mandrel; (d) using a hollow core, which is preferably disposed coaxially and contiguously with the second end of the mandrel, which core is sufficiently rigid to withstand deformation and reduction of the dimension of its opening under the effect an expansion force acting towards the inside of the envelope as a result of the compression of this envelope; and (e) linearly moving the crimped and compressed casing section of the second end of the mandrel to the outer surface of the core to obtain a high compression ratio and efficiency and thereby to produce said force of expansion exerted inwardly of the envelope when the opening of the pleated stick contracts.

 Another aspect of the invention relates to a method of manufacturing a pleated and highly compressed envelope article comprising a core, which method comprises the steps of: (a) using a cellulosic food casing section having a moisture content of at least about 13% of the total weight of the casing; (b) sliding the inner circumferential surface of the cellulosic food casing section on a first end of a mandrel; (c) pleating said envelope section on the mandrel; (d) using a hollow core sufficiently rigid to withstand deformation and decrease in the size of its opening due to an expansion force exerted to the interior of the envelope as a result of the compression of the latter; (e) moving the pleated casing section of the second end of the mandrel to the outer surface of the core; and (f) further compressing the pleated casing section on the core to a high compression ratio and yield, to produce said expansion force inwardly of the casing. In this embodiment, the core is preferably supported by a second mandrel and the pleated casing section is transferred to the core and the second mandrel to undergo compression to the fully compressed state. In addition, the folded casing section supported by the mandrel can be moved to a second position before passing from the second end of the mandrel to the core. The core is preferably arranged coaxially and contiguously with the second end. chuck.

 Another form of the invention relates to a method of manufacturing a heavily compressed pleated envelope article having a core, said method comprising the steps of: (a) using a cellulosic food casing section having a moisture content of at least about 13% of the total weight of the casing (b) to use a hollow core sufficiently rigid to withstand the deformation and decrease of the size of its opening under the effect of a expansion force exerting towards the inside of the envelope as a result of the compression; (c) using a mandrel and longitudinally sliding the inner circumferential surface of the core on the outer circumferential surface of the mandrel; (d) longitudinally sliding the inner circumferential surface of the cellulosic food casing section on the outer circumferential surface of the core; (e) pleating the casing section on the core and on the mandrel; (f) compressing the pleated casing section on the web to a high compression ratio and yield, to produce said expansion force exerted inwardly of the casing t and g) longitudinally sliding the pleated and highly compressed envelope article having a core out of the mandrel.

 Another aspect of the invention relates to a method of manufacturing a pleated and highly compressed envelope article comprising a method comprising the steps of: (a) using a cellulosic food casing section having a content in moisture of at least about 13% of the total weight of the casing; (b) sliding the inner circumferential surface of the casing section on a first end of a mandrel; (c) pleating said envelope section on the mandrel; (d) compressing the pleated casing section on the mandrel to a high compression ratio and efficiency; (e) using a hollow core sufficiently rigid to withstand deformation and decrease in the size of its opening as a result of an expanding force exerting inwardly on the envelope as a result of compressing the latter and (f) longitudinally sliding the folded and compressed envelope section out of the first end of the mandrel and onto the outer circumferential surface of the core to obtain a compression ratio and efficiency. high and thus produce said expansion force exerted inwardly of the envelope when the opening of the folded stick contracts.

 In another form, the invention relates to a method of manufacturing a pleated and highly compressed envelope article comprising a core, which method comprises the steps of: (a) using a cellulosic food casing section having a moisture content of at least about 13% of the total weight of the casing; (b) sliding the inner casing section circumference on a first end of a mandrel; (c) pleating the envelope section on the mandrel; (d) using a hollow core sufficiently rigid to withstand deformation and decrease in the size of its opening due to an expansion force exerted to the interior of the envelope as a result of the compression of the latter; (e) moving the pleated casing section, supported by the mandrel, to a second position, preferably in linear alignment and coaxial with the core; (f) moving the pleated casing section of the first end of the mandrel to the outer surface of the core; and (g) further compressing the pleated casing section on the core to a high compression ratio and yield to produce said expansion force exerted inwardly of the casing. In this embodiment, the core is preferably supported by a second mandrel, and the stick formed by the partially compressed envelope is transferred to the core and the second mandrel to be compressed to bring it into contact with the mandrel. totally compressed state.

 The particular moisture content preferred for different types of envelopes may vary. In particular, the moisture content of pleated fibrous envelopes, moistened in a controlled manner and in the large range, is preferably in the range of about 16% to about 35% of the total weight of the shell.

 The preferred range of moisture content for intermediate sized envelopes may also be in the range of about 16% to about 35% of the total weight of the envelope.

 The smaller sized envelopes used for the manufacture of Frankfurt sausage products and the like preferably have moisture contents in the range of about 142 to about 18% of the total weight of the shell.

 The tubular core of the article according to the invention must; be rigid enough to withstand the deformation and decrease in the size of its opening due to the expansion force exerted into the interior of the envelope, knowing that a slight deformation and slight decrease in aperture occur but remain acceptable if they are not excessive. The diameter of the core may vary from about 9.5 mm to 12.5 cm or more, depending on the size of the shell and the required opening size. The thickness of the web wall may be varied to suit the particular article envelope, as well as its adaptation and use and, furthermore, depending on the material used for the core.

However, in general, it can be considered that the wall thickness of such a tubular core is between about 0.051 cm and about 0.254 cm.

The invention will be described in more detail with reference to the accompanying drawings by way of non-limiting examples and on which
FIG. 1 is an elevation of an apparatus that can be used to produce an article according to the invention, by implementing the method of the invention, this view showing the pleating operation carried out on a section of envelope advancing continuously
FIG. 2 is an elevation showing the completed pleating operation had the pleated casing section transported to the compression station of the apparatus of FIG.
FIG. 3 is a partial elevation showing the application of the compressive force to produce the stick length according to the invention on a web mounted on an extension of the pleating machine.
FIG. 4 is a perspective view, partially broken away, of the article according to the invention, showing the folded and compressed envelope placed on a hollow tubular core.
FIG. 5 is a perspective view, partially broken away, of a variant of the article according to the invention intended to be used as a tamping mandrel on a stuffing apparatus intended for the treatment of products in the form of pieces of meat ;
FIG. 6 is a perspective view of an embodiment of the article according to the invention that is particularly suitable for stuffing medium sized products, the core being able to be used as a support intended to be slipped on a stuffing mandrel; or, alternatively, as a stuffing mandrel for the apparatus itself;
FIG. 7 is a partial elevation of one embodiment of the article according to the invention suitable for stuffing small sausages, the core replacing the stuffing mandrel on the stuffing machine during manufacture.
FIG. 8 is a graph showing the fall adjustment versus compression ratio for soulless and core pleated sticks formed from a non-fibrous 48 m long and small diameter shell (size 25). , ie 21 mm)
FIG. 9 is a graph showing the coherence as a function of the compression ratio for coreless pleated sticks formed from a non-fibrous envelope 48 m long and of small diameter (size 25, ie 21 mm)
FIG. 10 is a graph showing the fall adjustment as a function of the compression ratio for webless pleated sticks formed from small diameter cellulose casings (sizes 17, 21 and 27, diameters of 15, 5 mm, 18.9 mm and 2?, 6 mm in the inflated state), without fibrous reinforcement, all the sticks of a particular dimension having the same length
FIG. 11 is a graph showing coherence as a function of the compression ratio in the case of the pleated soulless rods shown in FIG. 10
FIG. 12 is a graph showing the maximum compression ratio that can be obtained with soulless and core pleated sticks formed from fibrous envelopes of intermediate sizes in the size range of 43 to E0, for adjust on a 27.25 mm tamping mandrel: and
FIG. 13 is a graph showing the same relationship as in FIG. 12, for fibrous envelopes of intermediate dimensons, the sizes of which are between 70 and 100, so as to fit on a 39.52 mm tamping mandrel .

 The drawings, and more particularly Figs. 1 and 2, show a typical floating chuck type pleating machine, generally designated 11, and including a pleating mandrel 13 which passes through a pleating head 15. An inflated envelope 17 is advanced on the mandrel 13 by means of two feed rollers 19 and two complementary feed strips 21. The pleating head comprises a plurality of pleating wheels 23, usually three wheels, between which the inflated envelope 17 passes, these wheels pleating the envelope cooperating with retaining strips, in a manner well known to those skilled in the art. 'art. The pleating wheels are of the general type described in US Patent No. 3,461,484.

 The advance of the pleated casing 17 on the mandrel 13 is braked by a set of retaining strips 25 so as to cause substantially regular pleating and production of a partially compressed pleated casing. After the initial pleating and folding action, the envelope is transferred by the retaining strips downstream to the mandrel and towards a first collar 27.

 To effect the transfer of the pleated envelope onto the hollow and substantially rigid tubular core and complete its compression on this core, in accordance with the invention, the first collar 27 is tipped out of the path followed by the envelope and advance a pleated section, by hand, or by means of any conventional automatic device, to the position shown in Figure 2 until it bears against a second collar 29. In this position, the section of The pleated envelope is placed on the hollow tubular core 31 placed on a cut or reduced section of the mandrel 13, as shown in FIG. 3 which is an enlarged and detailed view of the right-hand side of FIG. shell 17 on the hollow tubular core 31 is effected by means of a compression device 33 which moves linearly towards the second collar 29 until the pleated casing stick having the desired length .

A holding disc or washer 35 may be advantageously inserted between the end of the casing 17 and the second collar 29 so that, when the article is removed, the casing is held securely on the hollow tubular core and can not slip out of the end of this soul.

 When a high density envelope and core article is completed in accordance with the operations described above, the second collar 29 is removed from its retaining position and the finished article is removed.

 The article according to the invention can be assembled, for example, by transferring the pleated envelope and partially compressed on its hollow tubular core 31, in the manner described above. FIG. 3 shows the section of folded envelope and partially compressed which is brought linearly on a core disposed coaxially with the mandrel 13 pleating, the core being advanced on a reduced diameter section of the mandrel, and the final compressive force being exerted by means of a compression device 33 .

 Other methods can be implemented to place a pleated envelope on a core. For example, in a floating chuck type pleating machine such as that described above, the pleated casing can be fully compressed on the mandrel of the machine and then discharged onto a tubular core. It is also possible to completely remove the folded and partially compressed casing section 11 from the pleating machine 11 by passing it over a transport bar or a support mandrel, and to move the entire section of casing to a independent compression apparatus where the folded envelope section is placed on a core and compressed. Alternatively, the core can be placed on the floating mandrel and then positioned so that the envelope is folded on this core, the pleated envelope , comprising the core, then being completely compressed on said core and the stick thus formed by the envelope completely compressed on the core being then discharged (withdrawn) from the mandrel.

 Another pleating system, employing a shrink mandrel pleating machine, is described in the aforementioned US Pat. No. 2,583,654. This type of pleating system can be used in the manufacture of the article according to the invention and it allows the pleating of the envelope directly on a core on which the envelope can then be compressed. In one embodiment, the core is placed on the pleating and retracting mandrel and is positioned thereon so that the envelope is pleated on the core, the pleated envelope being then fully compressed on the core. and the stick thus formed by the fully compressed envelope and the core then being discharged from the mandrel. In another embodiment, the envelope may be folded and compressed on the withdrawal mandrel in the conventional manner, and the envelope pleated and compressed can be slipped from the mandrel to the core. In another embodiment, the envelope can be folded and partially compressed on the withdrawal mandrel, the latter is then brought into a new position in which it is coaxial with the core, the stick formed by the pleated envelope and partially compressed is slid from the mandrel to the core, and the pleated stick is then completely compressed on the core.It is also possible to completely remove from the shrinkage pleating apparatus the folded and partially compressed envelope section. by unloading it on a transport rod or on a support mandrel, and then transferring the pleated and partially compressed rod from the transport rod or the support mandrel to the core which is mounted in an independent compression apparatus where the stick pleated is then completely compressed on the soul.

 Obtaining the maximum possible compression ratio with the article according to the invention requires the application of a high compressive force which, itself, induces significant forces, exerted radially inwards in the stick. formed by the folded envelope.

Since the preferred method of preparing the article according to the invention is to compress the pleated envelope while it is in place on its core, it will be appreciated that a low coefficient of friction between the envelope and the soul is desirable. Example VII (described in more detail below) shows that a high compression ratio can be obtained with a core made of a material such as a high density polyethylene having a relatively low coefficient of friction, compared to polypropylene or polystyrene whose friction coefficients are higher.

 FIG. 4 represents an article according to the invention, in particular a section of moisturized cellulosic food casing 27, pleated and compressed on a substantially rigid tubular core 31 at a ratio and a compression yield higher than those obtained conventionally. Figure 4 also shows retention discs which may be optionally disposed at both ends of the pleated casing section to maintain it in a compressed state on the core.

 FIG. 5 shows a presently preferred embodiment of a high-density core pleating performed on the collapsible tamping mandrel of U.S. Patent Application No. 261,313, filed by Beckman. and collaborators. In this embodiment, a tilting element 37 for retaining the casing is mounted on the hollow tubular core 31, inside an unfolded section of the casing 17, this section having been pulled from the length of the casing. pleated and compressed envelope, on the tilting retaining element and on the end of the stuffing mandrel and the tubular core, so that the unfolded section can be closed with a fastener to form a ligature for the product to be stuffed.A flange 39 is used, as shown, at the opposite end of the article to facilitate mounting of the article to the stuffing apparatus.

 Fig. 6 shows the high density article and core according to the invention, adapted for a carrier or support sleeve to be slid over the stuffing mandrel of a stuffing apparatus. When so used, a flange 39 of this article may be connected to a mechanism forming part of the tamping machine and imparting reciprocating motion to the entire sleeve to perform loosening operations when necessary during the process. stuffing.

An embodiment very similar to that shown in FIG. 6 may alternatively be used as a sleeve which encloses a calibrating or retaining element, in which case an unfolded section of the envelope must be pulled on this calibration element or retaining and on the end of the tubular core, and this unfolded trunk must be closed with a fastener to retain the product being stuffed.

Fig. 7 shows an article according to the invention adapted for use in stuffing sausages of small dimensions. This article comprises a mounting adapter 41 which is arranged to fit directly on a stuffing machine, the hollow tubular core 31 of the article thus providing the conventional stuffing mandrel. In this case, the envelope 17 is partially unfolded, pulled on a calibration element 43 and on the end of the mandrel tube where it is closed to form a ligature preventing the passage of the product during the stuffing operation. It is particularly advantageous to provide long lengths of envelopes in a stick of a given length for the stuffing of small sausages, since these articles are produced to a large extent on high speed automatic stuffing apparatus. article with envelope according to the invention allows the use of substantially larger envelope lengths, in a length of
stick, which increases the efficiency of the operation of such equipment and satisfies, at the same time, the dimensional criteria of high precision (for example their straightness) and the structural integrity (coherence) required to the enveloped articles to be used on such equipment.

 Figure 7 also shows the angle e of the fold of the envelope in the form of pleated stick according to the invention. Conventional pleating on modern pleating machines gives pleated casing sticks which have a visible angular offset between a plane perpendicular to the longitudinal axis of the stick and a plane containing the pleats resulting from pleating. A soulless stick having such a crease angle is found to have significantly higher consistency and structural integrity than would a similar stick if pleated so that the crease angle is perpendicular to the axis. longitudinal stick because the entire stick is substantially similar to a stack of cones nested in each other. The core confers sufficient structural rigidity so that the coherence no longer depends on the angle of the fold.

 One of the reasons why envelope sticks according to the invention can have a certain angle of folding is the resistance to the longitudinal growth of the stick. Folded envelope sticks, immediately after being unloaded from the pleating and / or compression mandrel, tend to exhibit some growth, which is the tendency of the pleated, compressed and unrestrained stick to elongate. In the case of pleated and compressed sticks without a core, there is another growth of the pleated envelope radially inwards in the opening of the stick, this phenomenon increasing in proportion to the retention of the longitudinal growth of the stick.

 The tendency of a pleated and compressed stick to plunge radially inwardly against the core produces an additional effect of locking the folds of the envelope against the outer surface of the core. With this advantageous effect, the tendency of the stick formed by the pleated and finished envelope to grow longitudinally is substantially reduced by the friction occurring between the plies, as well as by the frictional forces occurring between the plies and the core, so that that a minimum additional longitudinal restraint is sufficient to stabilize the dimensions of the article formed by the envelope stick.

EXAMPLE I
A section of fibrous casing of large size, 76.22 m in length and size 10, in commercial design, having a mean flat width of 19.18 cm and a wall thickness of 0.10 mm, is pleated using pleating means very similar to those described in the aforementioned patent No. 3,461,484. The shell has a moisture content of about 20 t based on the total weight of said shell. A lubricant based on mineral oil is used in a conventional manner. Oil is used indoors to reduce friction on the mandrel and oil is also used outdoors to prevent deterioration of the casing during pleating and excessive wear of the pleating rollers.

The mineral oil lubricant is applied internally at a flow rate of about 28 mg of oil per 100 cm 2 of envelope area, and externally at a rate of about 15.5 mg of oil per 100 cm 2 of envelope surface, these quantities having no apparent deleterious effect on the properties of the finished stick. The envelope is compressed from one end on a tubular core of high density polyethylene having an inside diameter of 9.53 cm and a wall thickness of 0.16 cm, so that a stick is obtained. pleated with a length of 58.42 cm.The article formed by this envelope is prepared on a floating mandrel type pleating machine, in a manner previously described, the pleated envelope being transferred, after pleating and slight compression , on a core which is arranged coaxially with the pleating mandrel, on a reduced diameter section of the latter, before being finally compressed in position on the core and discharged. An article consisting of a high density pleated casing stick having a core according to the invention and having a compression ratio of 130.4 and a compression yield of about 0.757 is thus obtained.

 For comparison with a control sample, a commercially available, 45 m long normal length of the same size and type of plastic casing is pleated and compressed until the desired length is obtained. same length of pleated rod 58.42cm, without core and that one also obtains a compression ratio of 78 and a compression yield of 0.390, with a lower diameter of opening of 92 mm.

Other coreless control samples, having a higher compression ratio and yield, give non-functional articles as a result of an excessive decrease in opening due to inward radial growth.

EXAMPLE II
The fact that very high forces are exerted inward of the opening of the envelope stick as a result of the pleating operation is demonstrated by an experimental work of pleating and compressing at ratios and compression performance. high, cellulosic casing samples of small size, namely of size (21 mm in diameter in the inflated state), without fibrous reinforcement, having a wall thickness of about 0.0254 mm. During the experimental work lengths of 25.61 m of cellulosic casing of size 25, each constituting about 5 samples, are folded using pleating means very similar to those described in the aforementioned patent No. 3,461,484, together with Twisting is applied to the pleated stick as described in the aforementioned US Pat. No. 3,397,069. The pleated stick is then compressed under a force of about 180 daN onto tubular cores having a wall thickness of 0.254 mm, 0.508 mm, 0.762 mm, 1.016 mm and 1.27 mm. The core articles are produced on a floating mandrel-type pleating machine, as described in more detail herein, except during the final compression exerted on the core, the web 31 being able to slide freely through the rear collar 29 (FIG. ), which causes effective compression of the envelope simultaneously at both ends. All tubular cores have an inside diameter of 1.30 cm and the compression, after pleating, is performed on a section of 1.27 cm diameter compression mandrel on which the souls can slide. The moisture content of all samples in the pleated state is about 16.5% by weight and a mineral oil is used as the internal lubricant (from about 2.17 to 3.1 mg / 100 cm 2) and as an external lubricant (up to about 10.85 mg / 100 cm 2).

The amounts of lubricant are not critical, but these values represent 1 lb. amounts usually used on the particular pleating machine and the particular type of envelope involved.

The upper part of Table I shows the inner diameter values of the cores immediately after they have been discharged or removed from the mandrel, and at least one day and up to 20 days after this operation. The reduction in the inner diameter of the cores is due to the large expansion force exerted inwardly of the casing and resulting in high compression ratios and efficiency. It should be noted that the degree of reduction of the opening of the core is a function of the diameter of the tube as well as the magnitude of the inward forces and the creep resistance of the core, (ie, a large envelope requires a core whose thickness is greater than that required by a small-sized envelope to withstand the same force exerted inwards, per unit area). It should be noted that the relatively low creep resistance of high density polyethylene allows a 0.254 mm thick web to compress until the inside diameter of this web (12.19 mm) is effectively less than that of the opening of the sample without soul.The opening of the envelope stick is obviously larger r12,19 + 2 (0,254) = 12,6987. TABLE I
Effects of compression force inwards
Core Wall Thickness 0.254 0.508 0.762 1.016 1.270 (mm) Conical Shaped Conical Shaped Conical Shaped Conical Shaped Conical Shaped
Compression Ratio of Core Samples
Tablet 133.4 140.8 134.9 132.3 127.1 125.1 115.3 124.1 123.0 116.5
Unloaded 115.5 125.0 122.5 121.5 114.7 120.2 113.5 115.2 119.7 111.4
Later 114.8 121.3 116.8 118.8 109.8 119.2 109.8 112.1 118.7 122.4
Effective inside diameter of the core (mm)
Unloaded 12.09 12.52 12.19 12.32 12.24 12.45 12.42 12.45 12.45 12.52
Later 11.81 12.19 12.12 12.32 12.19 12.37 12.24 12.45 12.32 12.50
Compression efficiency
Later 0.55 0.68 0.58 0.70 0.57 0.73 0.59 0.73 0.67 0.76
Samples without soul
Conical shaped
Compression ratio in the compressed state 136.5 141.5
Compression ratio at the time of unloading 111.7 125.4
Compression Ratio Later 90.1 114.7
Diameter of opening, unloaded 0.532 0.519
Diameter of the opening, later 0,509 0,487
Compression yield, latest 0.44 0.63
The lower part of Table I gives data for a sample of the same sized size envelope, pleated and compressed on a 14.605 mm mandrel, but without a core. Although a high compression ratio and compression yield are obtained with "conical" folds (114.7 and 0.63, respectively), there is an excessive reduction in the size of the opening (as determined by downward adjustment) and this reduction is commercially unacceptable.It is not appropriate to directly compare these data with those of the core article shown in Table I, since each of the samples with a core is compressed on a support core having an outer diameter that varies depending on the thickness of the wall of this core.

Two crease angles are used in the pleating tests shown in Table 1. The term "erect" refers to a crease fold angle greater than about 150, and the term "taper" refers to crease pleat crease angle. about 450. The "erect" folded samples are pleated using pleating means or rollers similar to those described in the US Pat.
No. 2,984,574. The compression ratio of the conical ply-free sample to the compressed state is to be compared with that of the soulless sample of 63 in Table II, where the stick is unusable due to lack of consistency.

 The material used for the core in the disk tests in Table I is high density polyethylene. For reasons of convenience, the cores are machined in thick-walled tube and the resulting rough outer surface substantially reduces the achievable compression ratio. An examination of Table I shows that for high density polyethylene webs a significant deformation of the opening of the envelope article appears even when the thickness of the core reaches 1.270 mm. Table I also shows that for a constant compression force (180 daN in this example), the final compression ratio obtained decreases proportionally to the increase in the thickness of the core (that is to say to the increase in the outer diameter of blade).

However, the compression efficiency also increases.

To maximize the compression ratio, tamping mandrel adjustment, and compression performance, the core design must take into account (a) the creep of the core as a result of the large forces acting towards the core. the inside of the envelope as well as the final required aperture size, (b) the reduction in the compression ratio that would occur if a thick-walled core was used, and (c) the cost of the material of soul.

 Other materials tried for the soul give similar results with regard to the deformation of the soul. Souls made of ABS tubing, namely an acrylonitrile-butadiene-styrene copolymer, behave satisfactorily for wall thicknesses substantially lower than those of high-density polyethylene cores, but ABS cores are less economical.

EXAMPLE III
The advantages offered by the high density and core cellulosic article with respect to yield and compression ratio are demonstrated by an experimental work of pleating and compressing, at high compression ratios and yields, cellulosic casing samples of size 25 (21 mm diameter in the inflated state), without fibrous reinforcement, having a wall thickness of 0.0254 mm. The moisture content of the envelope as pleated is about 16.5% by weight, and a lubricant consisting of mineral oil is used as shown in Example 11. Pleating means of the type used in and similar to those described in the aforementioned US Pat. No. 3,461,484 are used to pleat the casing, while a twist is imposed on the pleated baton, as described in the aforementioned US Pat. No. 3,397,069. Each stick is then compressed onto polypropylene tubular webs (polypropylene reinforced with talc) to be compared to a pleated casing by the same pleating methods, but compressed without a web. Articles made of a high density envelope , on a core, are produced on a floating chuck type pleating machine, described in detail herein, except that during the final core compression the core 31 is allowed to slide freely through the rear collar 29 (Figure 3), so as to effectively compress the core simultaneously by the two ends. In addition, to obtain a more uniform compression over the entire length of the pleated casing stick, it compresses about 24 meters of envelope at a time (compression in stages). The coreless samples and some of the core samples are designed to have a 12.45 mm drop fit. Other core samples are designed so that the tubular core can be used as a stuffing mandrel to be discarded. use. In these cases, the inside diameter of the core effectively equals the inside diameter of a 12.70 mm outside diameter stuffing mandrel, and the pleated article does not require any special "fall-in" value. relative to the stuffing mandrel. For all samples, the pleated envelope is compressed to form a final stick about 51 cm long. Approximately 10 samples of each of the core configurations and each of the coreless configurations consisting of envelope lengths between 48 and 68 m are prepared.

 The results of this test work are summarized in Table II. For soulless articles with an envelope length of 63 m or more, poor consistency leads to sticks that break and no fall adjustment is possible after one week.

For coreless articles with casing lengths of 58.2 to 60.5 m, radially inward forces due to envelope growth (after one week) reduce the size of the casing. pleated sticks to such an extent that they no longer meet the requirement of a 12.45 mm drop fit. By way of comparison, the best pleating methods available give a soulless stick consisting of a pleated casing 48 m in length, with an average compression ratio (on ten samples) of 94.6 and an average compression yield of about 0.491. A pleated and compressed cellulosic envelope article having a high density and having a core, according to the invention, designed to have a drop adjustment of 12.45 mm, is produced by the same pleating method. the inner opening of the core is about 59% of the diameter of the envelope in the inflated state. This article contains 60 m of casing and has an average compression ratio (out of ten samples) of 116.46 and an average compression yield of 0.653.

TABLE II
Envelopes of small dimensions

Without <SEP> Soul <SEP> With <SEP> Soul
<tb> For <SEP> fit <SEP> in <SEP> fall <SEP> of <SEP> 12.45 <SEP> mm <SEP> For <SEP> fit <SEP> in <SEP> For <SEP> chuck <SEP> to <SEP> throw
<tb> drop <SEP> of <SEP> 12.45 <SEP> mm <SEP> equivalent <SEP> to <SEP> a <SEP> mandrel <SEP> of <SEP> 12.70 <SEP> mm
<tb> Diameter <SEP> section <SEP> of
<tb> compression <SEP> (mm) <SEP> 14.605 <SEP> 14.48 <SEP> 12.45
<tb> Diam. <SEP> ext. <SEP> x <SEP> diam. <SEP> int. <SEP> of
<tb> soul <SEP> tuoulaire <SEP> (mm) <SEP> - <SEP> 14,48 <SEP> x <SEP> 12,95 <SEP> 12,45 <SEP> x <SEP> 11 18
<tb> Envelope Length <SEP><SEP> (m) <SEP> 48 <SEP> 56.2 <SEP> 59.5 <SEP> 60.5 <SEP> 63 <SEP> 65.2 <SEP > 67.5 <SEP> 60 <SEP> 69
<tb> Length <SEP> of <SEP> stick <SEP> (cm)
<tb> Tablet <SEP> 48.23 <SEP> 48.26 <SEP> 48.26 <SEP> 45.72 <SEP> 45.72 <SEP> 43.81 <SEP> 43.81 <SEP> 50 , 49 <SEP> 49.68
<tb> Unloaded <SEP> 51.61 <SEP> 51.43 <SEP> 52.09 <SEP> 50.52 <SEP> 51.46 <SEP> 50.60 <SEP> 51.03 <SEP> 51 , 10 <SEP> 50.34
<tb> 1 <SEP> week <SEP> 51.56 <SEP> 51.92 <SEP> 52.55 <SEP> 51.43 <SEP> 52.25 <SEP> 51.92 <SEP> 52.40 <SEP> 52.35 <SEP> 52.55
<tb> Rap.de <SEP> Compression <SEP> of <SEP> Stick
<tb> Tablet <SEP> 101.10 <SEP> 118.4 <SEP> 123.2 <SEP> 135.0 <SEP> 140.0 <SEP> 151.3 <SEP> 156.5 <SEP> 120 , 72 <SEP> 141,10
<tb> Unloaded <SEP> 94.50 <SEP> 111.1 <SEP> 114.1 <SEP> 122.2 <SEP> 124.4 <SEP> 131.0 <SE> 134.4 <SEP> 119 , 20 <SEP> 138.55
<tb> 1 <SEP> week <SEP> 94.60 <SEP> 110.1 <SEP> 113.1 <SEP> 120.0 <SEP> 122.5 <SEP> 127.7 <SEP> 130.9 <SEP> 116.46 <SEP> 133.40
<tb> Outside diameter <SEP> of <SEP> stick <SEP> (mm)
<tb> Tablet <SEP> NA <SEP> NA <SEP> NA <SEP> NA <SEP> NA <SEP> NA <SEP> NA <SEP> 24.59 <SEP> 25.02
<tb> Unloaded <SEP> 24.00 <SEP> 24.13 <SEP> 24.38 <SEP> 24.71 <SEP> 24.84 <SEP> 25.58 <SEP> 25.73 <SEP> 24 , 61 <SEP> 24.82
<tb> 1 <SEP> week <SEP> 23.93 <SEP> 23.82 <SEP> 24.13 <SEP> 24.13 <SEP> 24.38 <SE> 24.69 <SE> 24.94 <SEP> 24.38 <SEP> 24.99
<tb> Adjust <SEP> in <SEP> drop <SEP> of <SEP> stick <SEP> (mm)
<tb> Unloaded <SEP> 12.04 <SEP> 12.83 <SEP> 12.78 <SEP> 12.39 <SEP> 11.76 <SEP> 12.06 <SEP> 11.94 <SEP> 12 , 70 <SEP> 10.92
<tb> 1 <SEP> week <SEP> 12.55 <SEP> 12.19 * <SEP> 11.94 * <SEP> 11.81 * <SEP> BC * <SEP> BC * <SEP> BC * <SEP> 12.62 <SEP> 10.79
<tb> Yield <SEP> of <SEP> Compression <SEP> of
<tb> stick <SEP> (after <SEP> 1 <SEP> week) <SEP> 0.491 <SEP> - <SEP> - <SEP> - <SEP> - <SEP> - <SEP> - <SEP> 0.653 <SEP> 0.617
<tb> Stings <SEP> in <SEP> a <SEP> group <SEP> of
<tb> 5 <SEP> samples <SEP> 1 <SEP> 0 <SEP> 1 <SEP> 0 <SEP> 1 <SEP> 2 <SEP> 2 <SEP> 0 <SEP> 0
<tb> BC = Broken stick
NA = No data available * = Baton not functional because it does not satisfy the drop adjustment of 12.45 mm requested.

 These data also illustrate a preferred embodiment of the invention in which on the basis of a comparison of the falling fit, the core has an interior dimension of aperture at least as large as that which the same envelope would have. if it were wrinkled and strongly compressed under the same conditions of pleating and compression, without soul, and at the same compression ratio. In particular, the dimension of the opening of the core of articles having an average compression ratio of 116.46 is 12.62 mm.

In comparison, the dimensions of web-free pleated stick openings, having compression ratios of 113.1 and 120.0, are 11.94 and 11.81 mm, respectively, which is substantially less than the the comparable article with a soul.

 A second series of high-density samples, having a core, is produced, the core of the pleated article being used as a disposable stuffing mandrel, having a permissible flow rate effectively equivalent to that of a normal mandrel. padding 12.70 mm outer diameter (11.07 mm ID). An article is thus obtained in which the inner opening of the core is equal to approximately 51% of the diameter of the envelope in the inflated state. This article comprises 69 m of casing with an average compression ratio (over ten samples) of 133.4 and an average compression yield of 0.617.

 The test was continued to determine the quality of the pleated and compressed envelope articles of this Example III (both core and soulless), this quality being evidenced by the number of pits present in the pleated envelope. Five sticks of each type of sample were tested for pitting by filling the envelope with water and pressurized internally. The results given in Table II show a general tendency to increase pitting deterioration as the total length of the casing of the article without a core increases. On the other hand, no sting was found in the samples with a core subjected to the tests.

 In summary, Example III shows that it is not possible to prepare a typical, small, soulless, pleated and compressed cellulosic casing at a compression efficiency of at least 0.5, with no unacceptable decrease in the opening (diameter). On the other hand, this result is easily obtained with the article according to the invention and, in fact, the preferred compression yield of at least 0.6 is exceeded.

EXAMPLE IV
Another advantage of the high density pleated casing article and core according to the invention is that it reduces the tendency for envelope damage, ie pitting, compared to the same casing. wrinkled and compressed in the same conditions, but without soul. This is due to the fact that the core reduces longitudinal growth due to surface friction and requires lower compression to maintain a particular compression ratio compared to a pleated rod without a core. Since pitting increases with compression, the article of the invention makes it possible to reduce or avoid the possible problem of deterioration of the envelope.

 In addition, the core allows to maintain and set the compression ratio in the fully compressed state and it allows to further increase the compression ratios without pitting deterioration.

 This compressional relationship between the core and soulless pleated-shell sticks is illustrated by a series of tests in which lengths of 48 m of non-fibrous, size 25 cellulosic casing are pleated and compressed in an equivalent manner with and without a soul, up to a length of 38 cm and an initial compression ratio of 128. After unloading, the pleated sticks, with soul and without soul, are allowed to grow for a period of seven days, without additional longitudinal retention. At this stage, the core article has a longitudinal growth of only 10.16 mm (compression ratio after growth of about 125), while the coreless article has a growth of 35.5 mm (ratio of compression after growth of about 117). If the objective had been a final compression ratio of 125, it would have been necessary to exert a higher initial compressive force in the case of the pleated stick without a core.

 The advantage of the lower tendency to deterioration of the envelope can be used in another way. If the user indicates a maximum compressive force that can be applied without causing deterioration of the envelope upon application of this force, the core article may be formed at a higher compression ratio and at a higher efficiency. compression higher than the article without soul.

EXAMPLE V
A series of tests are carried out on the basis of the teachings of the aforesaid British Patent No. 1,167,377, and the results thus obtained are compared with the high density pleated cellulosic stick and core according to the invention.

 Based on the indications given in the aforementioned British patent, a 40.97 mm ID polyvinyl chloride tube and a core having a wall thickness of 0.254 mm are used, and a cellulosic fibrous reinforcement shell of 2.5 cm (about 6.1 cm diameter in the inflated state) is folded by a pleating apparatus similar to that described in the aforementioned patent No. 3,461,484, and then compressed to a length of 30.5 cm. The 40.97 mm inner diameter tube and the 2.5 size fibrous casing are chosen for this test because the tube is the smallest polyvinyl chloride tube available at the time of the test. The casing is prepared on a floating mandrel type pleating machine, as described in more detail above, the pleated casing being transferred, after pleating, to a core disposed coaxially with the pleating mandrel, on a section of reduced diameter of the latter, then finally compressed as described in Example I, and discharged. These samples have a moisture content, in the pleated state, of about 20% and a mineral oil lubricant is used indoors (at about 31 mg / 100 cm 2) and outside (up to about 16.5 mg / 100 cm2). The envelope is used in three different lengths 22.5 m, 30 m and 37.5 m. Based on the compressed article, different compression ratios are obtained. The articles obtained are then measured to determine the inner diameter of the core by the "fall-in" method described above. . In the case of the sample having a compression ratio of 75, the size of the falling fit is 40.39 mm, which indicates a reduction in the core diameter dimension of 0.584 mm. In the case of the sample having a compression ratio of 100, the size of the falling fit is 39.12 mm, indicating a decrease in core diameter of 1.854 mm. In the case of the sample having a compression ratio of 125, the size of the fall adjustment is less than 38.10 mm.

However, the core deforms at one end immediately after the article has been compressed and discharged from the mandrel.

This shows the inability to obtain the high-density and high-density pleated cellulosic stick according to the invention by following the indications given in the aforementioned British patent.

 The 22.5-meter-long sample still fits on the 39.52-mm outer diameter stuffing mandrel, but the compression yield is only 0.43. Samples 30 m in length have such a large reduction in opening that they can not fit on the mandrel. The core of the 37.5 m long sample closes completely.

EXAMPLE VI
Fibrous cellulosic casing articles of dimensions similar to those of the sample of the type described in Example V, prepared in accordance with the aforementioned British Patent No. 1,167,377, are prepared in accordance with the invention and compared to samples without a core so To determine the limits of compressibility as established by the deterioration of the envelope. Envelopes of size 2.5 (about 6.1 cm in diameter when inflated) and size 4 (about 7.1 cm in diameter when inflated) are folded by a pleating machine similar to that described in the above-mentioned patent No. 3,461,484. The moisture content of the size 2.5 and size 4 shrunken samples in the pleated state is about 20%. A mineral oil is used as a lubricant in the following manner
size 2.5: about 31 mg / 100 cm2 (inside) and
about 15.5 mg / cc; (outside)
size 4: about 26 mg / 100 cm2 (inside) and
about 14 mg / 100 cm2 (outside)
The core articles are compressed on polyvinyl chloride cores, in a manner identical to that used for the articles of Example V. The samples are compressed to a length of 30.5 cm, at a ratio of compression of 150, which is the highest compression ratio achievable without damage to the 2.5-size envelope. All samples are made to fit on a 39.52 mm padding mandrel of diameter. The cores used have an outer diameter of 43.51 mm and a wall thickness of 1.27 mm. The core samples are retained so that they can not be longitudinally expanded by means of a tenon, and the soulless samples are retained (only partially) as boxes in a cardboard box.

 The results of the tests are given in Table III. The size 2.5 articles, having a core, have a final dimension of the opening of the blade slightly too small to fit on the mandrel, but larger than that of opening the articles without a core. when even the core articles have a compression ratio of about 13S, whereas the soulless articles have a compression ratio of only about 114. In practice, a ratio of slightly lower compression would have allowed the core to fit properly on the mandrel. The size 4 articles, including a core, are functional (with respect to the compression ratio) after 15 days at a compression ratio of 138 46. Soulless size 4 articles have a decrease in aperture rendering them unsuitable for use after 15 days, with a measured compression ratio of 128.48.

 Example VI also illustrates, in the case of fiber reinforced and core reinforced articles, a preferred embodiment of the invention in which, on the basis of a comparison of the falling fits, the core exhibits internal opening dimension at least as large as that which would have the same fibrous envelope wrinkled and strongly compressed under the same conditions of pleating and compression, but without core, and at the same compression ratio in the compressed state. For example, with the size envelope 2.5, the average dimension of the aperture of the coreless envelope, which is 39.12 mm, is slightly smaller than the average dimension of the inner aperture of the shell with core, which is 39.29 mm, even though the final compression ratio of this last article is substantially greater (138 instead of 114). Similarly, with the envelope size 4, the average size the aperture of the coreless envelope, which is 39.29 mm, is substantially less than the average dimension of the aperture of the core envelope, even though the latter's final compression ratio is higher (138 instead of 128).

 A comparison of the results of the tests described above with those obtained in Example V shows that the aforementioned British Patent No. 1,167,377 does not indicate or even suggest the use of a core in a manner that makes it possible to obtain Simultaneously, the three advantageous features of the cellulosic casing article and the core according to the invention are: a high compression ratio; a high compression ratio; and a limited deformation-reduction of the aperture of the core.

TABLE III
FIBROUS ENVELOPE (for 39.52 mm diameter stuffing mandrel)

<SEP> Envelope of <SEP> Size <SEP> 2.5 <SEP><SEP> Envelope of <SEP> Size <SEP> 4
<tb> (6.1 <SEP> cm <SEP> of <SEP> diameter <SEP> to <SEP> the state <SEP> (7.1 <SEP> cm <SEP> of <SEP> diameter <SEP > to <SEP> the state
<tb> swollen) <SEP> swollen)
<tb> with <SEP> soul <SEP> without <SEP> soul <SEP> with <SEP> soul <SEP> without <SEP> soul
<tb> Diameter <SEP> outside <SEP> x <SEP> diameter <SEP> inside <SEP> of
<tb> the tubular <SEP> core <SEP> (mm) <SEP> 43.51 <SEP> x <SEP> 40.97 <SEP> - <SEP> 43.51 <SEP> x <SEP> 40 , 97 <SEP>
Length <SEP> of <SEP> Envelope <SEP> (m) <SEP> 45 <SEP> 45 <SEP> 45 <SEP> 45
<tb> Number <SEP> of samples <SEP> 9 <SEP> 17 <SEP> 9 <SEP> 17
<tb><SEP> report of <SEP><SEP> compression <SEP><SEP> stick (average)
<tb> 2 <SEP> days <SEP> 138.46 <SEP> 114.28 <SEP> 138.46 <SE> 130.91
<tb> 15 <SEP> days <SEP> 138.46 <SEP> 113.92 <SEP> 138.46 <SEP> 128.48
<tb> Adjustment <SEP> in <SEP> fall <SEP> of <SEP> stick <SEP> (average) <SEP> (mm)
<tb> 2 <SEP> days <SEP> 39.73 <SEP> 39.42 <SEP> 40.21 <SEP> 39.37
<tb> 15 <SEP> days <SEP> 39.29 <SEP> 39.12 <SEP> 40.18 <SEP> 39.29
<Tb>
EXAMPLE VII
A series of tests is carried out using a pleating machine of the type described in the patent
No. 3,461,484, at the same time as a twist is applied to the pleated stick, as described in the patent
No. 3,397,069 cited above. In these tests, small diameter, high density, core-pleated cellulosic envelope articles are prepared using different materials for the cores. The core articles are produced on a mandrel type pleating machine. floating, as described in detail in this specification, except that during the final compression performed on the core, the web 31 is allowed to slide freely through the rear collar 29 (FIG. 3), which allows effective compression of the envelope simultaneously by its two ends. The materials used for the cores during these tests are polypropylene (reinforced with a 20% talc load), polystyrene and high density polyethylene, each core having an outer diameter of 12.70 mm and a thickness of wall of 0.635 mm. The envelope used is a size cellulose wrap (without fibrous support), and each wrapped article contains 60 m of wrap. On all samples, the moisture content in the pleated state is about 16.5% and mineral oil is used as a lubricant, indoors (about 2.2 to 3.1 mg / 100 cm2) and outdoors (up to about 11 mg / 100 cm2).

 The results of the tests, grouped in Table IV, show that the relatively lower coefficient of friction of the high-density polyethylene core makes it possible to compress the pleated envelope at a compression ratio substantially greater than that obtained with the other constituent materials of souls.

 According to the work of the tests described in Examples II and VII, it can be seen that the design of a core for the article according to the invention is bscc on properties of the material constituting the core, such as the resistance mechanics, modulus of elasticity and creep resistance. These properties determine the thickness that must be given to the wall of the core to withstand the expansion forces exerted inwardly of the envelope and tending to deform and reduce the size of the opening of the shell. 'soul. The coefficient of friction of the core material determines the magnitude of the longitudinal compressive forces that must be exerted to compress the envelope to achieve extremely high compression ratios.

 It appears that many factors are to be considered in the choice of the material of the soul, these factors including the coefficient of friction, the resistance to creep, the modulus of elasticity, the availability in extruded form, the cost, the fitness, weldability and availability in reinforced form.

The material finally chosen may differ according to different applications. High density polyethylene and polyvinyl chloride are suitable for large size envelopes according to the invention.

TABLE IV
LOW DIMENSION ENVELOPE
Tubular core ... 12.70 mm outer diameter x 11.43 mm inner diameter (for use as a stuffing mandrel)
Envelope ... size 25; Cellulose; 60 m in length
Matter of the soul

Polypropylene <SEP> reinforced <SEP> Polyethylene
<tb> of <SEP> talc <SEP> Polystyrene <SEP> high <SEP> density
<tb><SEP> report of <SEP><SEP> compression of the <SEP> stick
<tb> Tablet <SEP> 149.3 <SEP> 148.0 <SEP> 174.0
<tb> Unloaded <SEP> 139.5 <SEP> 142.0 <SEP> 158.7
<tb> 1 <SEP> week <SEP> 137.1 <SEP> 140.4 <SEP> 150.9
<tb> Adjustment <SEP> in <SEP> fall <SEP> of <SEP> stick <SEP> (mm)
<tb> Unloaded <SEP> 10.67 <SEP> 10.92 <SEP> 10.92
<tb> 1 <SEP> week <SEP> 10.67 <SEP> 10.92 <SEP> 10.92
<Tb>
EXAMPLE VIII
Another series of tests is carried out on high density and core envelope articles, similar to those described in Example III and grouped in Table II. The only difference is that instead of making a final compression at both ends, the compression is done at one end, in the same way as that used for the pleated and soulless envelopes, given in Table II. , and the pleated sticks and tablets are transferred on lamez
The results of these tests on high density and core articles, comprising a non-fibrous cellulosic casing of size 25, are grouped in Table V and compared to the data on a casing without a core, shown in Table II.

The high density article and core, intended to have a drop adjustment of 12.45 mm, has an average compression ratio (on 15 samples) of 129.2 and an average compression yield of 0.67. The high density article and core, intended to serve as a tamping mandrel of 12.70 mm outside diameter, has a mean compression ratio (on 15 samples) of 140.1 and an average compression yield of 0.64 .

 In summary, while Example III shows that it is not possible to prepare a typical, small, soulless pleated and compressed cellulosic casing having a compression yield of at least 0.5, proceeding at a single end compression, without showing a high and unacceptable decrease of the opening, this result is easily obtained with the article according to the invention and, in fact, the preferred compression yield, which is from less than 0.6, is exceeded.No equipment was available to proceed to a compression by both ends of sticks without soul.

TABLE V
LOW DIMENSION ENVELOPE
For adjustment For a chuck
in fall throw equivalent to
12.45 mm a mandrel of 12.70 mn
Diaphragm Compression Section (mm) 14.60 13.00
Outer diameter x inside diameter of 1 tubular core (mm) 14.22 x 12.95 12.70 x 11.43
Length of envelope (m) 60 60
Stick length (mm)
Tablet 432,381
Unloaded 473,434
1 week 472,435
Camming report of the stick
Tablet 141.2 160.0
Unloaded 128.8 140.3
1 week 129.2 140.1
Outside diameter of the stick (mm)
Cooperative NA NA
Unloaded 24.97 23.85
1 stiaine 24.87 25.07
Falling fit of the stick (mn)
Unloaded 12.65 10.92
1 week 12.55 10.74 Stick compression efficiency (after 1 week) 0.67 0.64
NA = No data available.

EXAMPLE IX
Another series of tests is carried out, in which a cellulosic casing of size (without fibrous reinforcement) is used for the preparation of high density, soulless and core pleated articles at various compression ratios. items under review for fall adjustment (Figure 8) and consistency (Figure 9). All articles are prepared from 48 m of envelope and the pleated and compressed articles have different lengths that depend on the compression ratio. The moisture content of the envelope as pleated is about 16.5% by weight. weight, and mineral oil is used as an internal lubricant (about 2.2 to 3.1 mg / 100 cm 2 internal surface) and as an external lubricant (up to about 11 mg / 100 cm 2 external surface) during the pleating.

 Pleating means of the type described in the aforementioned US Pat. No. 3,461,484 are used to pleat the casing, while a twist is applied to the pleated baton, as described in the aforementioned US Pat. No. 3,397,069.

The envelope is fully compressed in the conventional manner, from one end, on the compression section of the mandrel of a floating mandrel-type pleating machine, as shown generally in FIG. 3. After compression, the stick with pleated envelope is discharged directly on a tubular core. The latter is made of polyvinyl chloride and has an outer diameter of 14.22 mm and an inner diameter of 12.85 mm. In a first group of tests, a mandrel having a compression section of 14.60 mm in diameter is used. For the other group of tests, the diameter of the compression section of the mandrel is 15.11 mm.

 Falling fit and consistency of the high-density, soulless and core-pleated articles are measured, as is the compression ratio, 7 days after unloading, and the data thus obtained are plotted against the ratio of compression in Figures 8 and 9.

 Figure 8 shows that the fall adjustment for pleated and compressed coreless sticks (formed on mandrel compression sections of 14.60 mm, as indicated by curve A, and 15.11 mm, as indicated by curve B) decreases continuously as the compression ratio increases in the range of 95 to 120, the compression ratio being indicated on the abscissa and the falling fit being indicated on the ordinate in millimeters. Since the minimum acceptable size of the opening of a size envelope (21 mm diameter in the inflated state) is 12.45 mm (horizontal dashed line), the maximum compression ratio that is can be used with the 14.60 mm mandrel is about 99.It should be noted that using a larger mandrel (15.11 mm), the minimum opening dimension can be achieved with a slightly compression ratio higher (about 103), but this increases the risk of deterioration of the envelope by pitting. In addition, when increasingly larger mandrel sections larger than about 14.60 mm are used for a size 25 envelope, there is a progressive increase in the risk of locking on the mandrel, interruption of production and percentage of waste. In other words, it is recognized by those skilled in the art that, in the field of pleating, the optimum setting to allow a pleating without problems of a particular dimension envelope is that using the smallest mandrel giving the opening of desired size.

 In comparison with the limitation, indicated above, of the compression ratio of a pleated rod without a core, due to the dimension required for the opening (this limit ratio being about 99), FIG. size 25, having a core, the fall adjustment is constant when the compression ratio rises to a value of about 124 and the same 14.60 mm mandrel (curve A) is used.

If the compression ratio is further increased, the inner opening of the core begins to deform inward under the effect of the excessive force exerted inwards by the pleated stick. Therefore, the value 124 represents a practical upper limit of the compression ratio for this particular embodiment in which the diameter of the envelope in the inflated state is about 21 mm, the compression ratio is greater than 100 and the fall adjustment is at least 12.45 mm.

 It has been unexpectedly discovered that when the compression ratio of soulless pleated sticks consisting of a cellulosic casing (with fibrous reinforcement) is in the range of the compression ratio that can be obtained with the article soul envelope according to the invention, the coherence of sticks without soul gradually decreases as the compression ratio increases. This is contrary to the predictions, because at lower compression ratios such as those used in industrial practice, it is known that the consistency of the same soulless stick increases progressively with the compression ratio.

 This unexpected finding, that coherence decreases as the compression ratio increases in the case of soulless pleated cellulosic envelope sticks, is illustrated in FIG. 9 for a size envelope 25, the coherence being given on the ordinate and the ratio of compression on the abscissa. It should be noted that for a 14.60 mm mandrel, the coherence decreases almost constantly and drops rapidly from about 5 (compression ratio of 100) to a value at least as low as 1.5 (compression ratio of 125). The last compression ratio is only slightly higher than the minimum commercially acceptable consistency of 1.2, and is substantially less than the preferred consistency of 2.5. High density pleated casing article and core according to the invention, no limitation is imposed on coherence because the pleated and compressed envelope is supported by the outer wall of the core with which it is in operative contact.

 It is believed, without fully understanding it, that the aforementioned relationship between coherence and compression ratio, in the case of pleated and soulless cellulosic envelope sticks, depends on the degree of compression of the folds of the envelope. One possible explanation is that in the lower range of compression ratios, ply compression generates a narrower engagement of the cones into each other, which increases the contact area between adjacent cones and, consequently, the coherence of the cones. . However, when the compression is further increased to reach even higher compression ratios, the high compression can break the cones fit, which reduces coherence.

This possible explanation is in accordance with the experimental observation that, when the compression ratio of the coreless cellulosic envelope sticks is progressively increased, the coherence initially rises to a maximum value and then gradually decreases. The possible explanation is also consistent with the experimental observation that larger envelopes have higher coherences, at higher compression ratios, than smaller sized envelopes (Figure 11 described below). This may be due to the larger areas by which adjacent cones are in contact with each other in relatively large envelopes.

The size 48 envelope data, 48 m in length, shown in FIGS. 8 and 9, also support the main criteria required according to the invention, namely that the core article must have a compression efficiency which is not less than 0.50, and its compression ratio and compression performance are respectively greater than those of the same casing length, pleated and strongly compressed under the same pleating and compression conditions, but without soul. In particular, the characteristics presented by the samples after 7 days, (a) the core article having the highest compression ratio that satisfies the minimum drop adjustment of 12.45 mm requested, (b) a soulless article that is pleated and compressed under the same conditions as sample (a), and (c) the article without a core having the highest compression ratio, which also satisfies the same minimum dropped fit requested, are as follows
Adjustment Performance Report of
Sample in fall compression compression (a) article with me 12.70 mm 124 0.66 (b) article without core 11.68 mm llo o, 4 (c) article without core 12.70 mm 98 0.44
These data show that the fall adjustment, the compression ratio and the compression yield of the sample (a) are all greater than those of the sample (b). In addition, the sample (b) is not an acceptable product because the stick has a growth towards the inside of the opening, this growth being such that the stick of the sample (b) does not satisfy the minimum fall adjustment requested. Knowing this defect of the opening of the sample (b), the article without soul (c) constitutes the best soulless pleated stick that could perform the same function as the soul article (a). On this basis, sample (a) represents an improvement of 26% in compression ratio and 50% in compression efficiency.

EXAMPLE X
Another series of tests, similar to the tests of Example IX on a size envelope 25, is carried out with three different sizes (smaller and larger) of cellulosic casings, without fibrous reinforcement. These envelopes are of size 17 (diameter 15.5 mm in the inflated state and wall thickness of 0.025 mm), size 21 (18.5 mm diameter in the inflated state and wall thickness 0.025 mm) and the size 27 (diameter of 22.6 mm in the inflated state and wall thickness of 0.025 mm). One difference from the tests of Example IX is that, instead of using the same length of envelope and to prepare different lengths of sticks according to the compression ratio, in these tests, the length of the envelope is varied and the sticks are compressed so as to have substantially the same final length for each envelope size ( 7 days after unloading germinate). In the case of the size envelope 17, the final length of the stick is about 40.5 cm, while this length is about 52.1 cm in the case of size 21 and 27 envelopes.

 Another difference between these tests and those of Example IX is that soul articles are not prepared from an envelope of size 17, size 21 or size 27. However, in another test Similarly, a high density pleated cellulosic casing article is prepared from a size envelope 21 and has the following features a compression ratio of 119.8; a compression yield of 0.66; and a dimension of the inner opening of the core of 10.72 mm. Therefore, this pleated and core wrapped article is suitable for use on the intended stuffing mandrel with an outer diameter of 10.31 mm. As shown by the curves corresponding to the pleated, soulless stick for the size 21 envelope. in Figures 10 and 11 (described hereinafter), these outstanding features can not be even approximated by the coreless crimped envelope of the prior art.

 Except for the aforementioned differences, the high density, soulless pleated poles are prepared from size 17, 21 and 27 envelopes in the same manner as for the high density, soulless pleated poles of size 25. After unloading and storage for 7 days without longitudinal restraint, the sticks obtained are subjected to fall and coherence adjustment measures.

The data is summarized by the curves of Figure 10 (falling fit) and Figure 11 (consistency), as a function of the compression ratio.

 An examination of FIG. 10 shows that, as for size envelope 25 (FIG. 8), the fall adjustments of the three envelope sizes decrease progressively and substantially consistently as the compression ratio increases, fall adjustment being indicated on the ordinate, in millimeters, and the compression ratio on the abscissa. In the case of the size 17 envelope, the minimum acceptable drop adjustment is 9.14 mm (indicated by the dashed horizontal line), so that from the point of view of the fall adjustment, the maximum ratio The compression ratio that can be achieved with the prior art coreless pleated stick is about 80. In the same way, with the size envelope 21, the minimum acceptable drop adjustment is 10.41 mm, so that the maximum compression ratio achievable with the prior art coreless pleated stick is about 98. Finally, with the size envelope 27, the minimum acceptable drop adjustment is 13.46. mm, so that the maximum compression ratio achievable with the prior art coreless pleated stick is about 130.

 If we now consider the curves giving coherence as a function of the compression ratio, in FIG. 11, we see that all these curves show the unexpected relationship, described above, according to which the coherence decreases when the compression ratio increases in the upper range of compression ratios for each envelope size. For size 17, consistency is low over the entire range of 60-125 compression ratios, knowing the minimum acceptable value of 1.2 (horizontal dashed line). In the case of the pleated envelope without size 17 core, the maximum compression ratio that can be achieved, taking into account the coherence, is also about 80. For size 21, the coherence is also low over the entire tested range of compression ratios of 70-120, and based on the minimum acceptable consistency value of 1.2, the maximum compression ratio achievable, given the consistency, is about 102.

 In the case of the crimped and size 27 cored shroud, the full range, mentioned above, of relationship between consistency and increasing the compression ratio is illustrated. In other words, for compression ratios up to about 120, consistency increases as the compression ratio increases.

However, beyond the compression ratios of about 122, the coherence decreases at a roughly constant and relatively high rate.

 FIGS. 10 and 11 show that the required drop adjustment and consistency place significant restrictions on the use of high compression ratios with prior art coreless crimped sticks formed from cellulosic casings of the sizes. 17, 21 and 27. In each case, the article according to the invention makes it possible to achieve substantially higher compression ratios with an acceptable core opening dimension and a higher coherence, and also with a lower tendency to deteriorate the envelope by pitting. In particular, a pleated envelope article of size 17, with a core, according to the invention, consisting of an envelope having a diameter of approximately 15.5 mm and having a drop adjustment of at least 9.14 mm, preferably has a compression ratio greater than 80.Furthermore, an article consisting of a pleated casing of size 21, with core, according to the invention, comprising an envelope of approximately 18.54 mm diameter in the state which is inflated and has a fall adjustment of at least 10.41 mm, preferably has a compression ratio of greater than 98. Finally, a pleated envelope article of size 27, with core, according to the invention, comprising an envelope having a diameter of about 22.6 mm in the inflated state and having a fall adjustment of at least 13.46 mm, preferably has a compression ratio greater than 130.

EXAMPLE XI
The advantages of compression ratio and performance of the embodiments of the invention, comprised of fibrous reinforcement-type envelope articles of intermediate dimensions, are demonstrated in another series of sample tests. with soul and without soul. Envelopes of sizes 43, 47 and 60, having flat widths of the order of about 58.5 to 83.8 mm, are used for the preparation of pleated and compressed stick articles with a core and without a core , intended to fit on a stuffing mandrel with an outside diameter of 27.25 ± 0.127 mm. Envelopes of sizes 70, 80 and 100, having flat widths of the order of about 95.25 to 139.7 mm, are used for the preparation of pleated and compressed sticks, core and coreless, intended to fit on a tamping mandrel with an outside diameter of 39.52 + 0.127 mm.

The shell wall thickness of each of the samples is about 0.0737 mm. The moisture content of the shell as pleated is about 20%, and a mineral oil is used as the internal lubricant. (at about 6.8 mg / 100 cm internal surface) and as an external lubricant (up to about 4.6 mg / 100 cm 2 external surface). The diameters in the inflated state of these envelopes with fibrous reinforcement are as follows
Size Diameter in the inflated state (mm)
43 37.59
47 40.33
60 52.40
70 60.63
80 70.41
100 88.52
During these tests, different lengths of envelope are compressed so that sticks having substantially the same length, at all compression ratios, are obtained for a particular envelope size. These lengths presented by the compressed sticks are the following ones: 26.7 cm for size 43; 25.4 cm for size 47; 22.9 cm for size 60; and 30.5 cm for sizes 70, 80 and 100.

 All shelled article samples are prepared on a floating chuck type pleating machine as previously described. The pleating means are of the type used in industry and similar to those described in the aforementioned patent No. 3,461,484. Multiple samples are prepared under each condition. The coreless samples are crimped and compressed from one end on the mandrel to the maximum compression ratio allowed without envelope damage and at lower compression ratios.

The maximum compression ratio "without deterioration" is determined by tests to detect the presence of holes and consisting of filling the envelope with water and applying an internal pressure. When deterioration is detected, other samples are prepared at slightly lower compression ratios and are subjected to the water test for pitting as indicated. The cycle is repeated until a compression ratio is achieved giving intact envelopes, and this ratio is the maximum compression ratio.

 After compression on the mandrel, the coreless samples, sizes 43, 47 and 60, are transferred from the pleating machine to a small diameter plastic tube (27.9 mm) for handling, and after about one hour, they are removed from the tubes and introduced into a net. The latter is ligated at both ends and the wrapping net, thus ligated at the ends, is the industrial practice used to facilitate handling. This arrangement confers a slight restraint against longitudinal growth.

The soulless samples, sizes 70, 80 and 100, are transferred directly from the pleating machine into a polyvinyl chloride film which envelops them and which exerts a very limited extreme restraint. This operation is also a commercial practice designed to facilitate handling.

 The souls are made of rigid polyvinyl chloride. In the case of envelope sizes 43, 47 and 60, the outer diameter of the core is 31.24 mm and the thickness of the wall of the core is 1.27 mm. In the case of the envelopes of sizes 70, 80 and 100, the core has an outer diameter of 43.51 mm and a wall thickness of 1.27 mm also.

 After pleating, the samples to receive a core are moved longitudinally from the mandrel to webs that are disposed coaxially with the pleating mandrel, around a reduced diameter portion of the mandrel, as previously described and illustrated in FIG. The pleated stick is then compressed on the core, at one end, to the desired compression ratio, and then unloaded. Core samples are compressed to compression ratios equivalent to those used for samples without a core.

 After unloading, the pleated and core wrapped article receives means equivalent to the web-mounted holding disks 35 and the flange 39 (as shown in Fig. 6), placed at opposite ends of the pleated stick to maintain the length discharged during the storage period of 7 days. This degree of extreme retention in the longitudinal direction is not ensured in the case of sticks without core, because they may then deform or inward enough to not be able to be adjusted on the desired stuffing mandrel . Therefore, the net and wrapping plastic film used with the soulless sticks do not provide significant longitudinal restraint.

 The lengths of the sticks are measured before unloading, both in the case of the core and core samples, and are measured again after the 7-day storage period. The results of these measurements are given in FIG. 12 for the fibrous reinforcement envelopes of the sizes 43, 47 and 60, and in FIG. 13 for the fibrous envelopes of the sizes 70, 80 and 100, with compression ratios given according to FIG. of the flat width of the envelope, the compression ratios being indicated on the ordinate and the flat width of the envelope being given on the abscissa, as well as the size of the envelope.

 In Figures 12 and 13, the lower curve represents the pleated and compressed stick, without soul, after 7 days of storage. The median curve represents the pleated and compressed article, with core, also after 7 days of storage, and the upper curve (in dashed lines) represents the wrinkled and compressed article, with core, immediately after compression. This last curve is indicated because it represents a state that can be obtained with the invention, but which can not be obtained with a pleated and soulless stick of the prior art. In other words, by "blocking" the opposite ends of the core article after compression, but before unloading, for example by means of extreme longitudinal retaining elements, the initial (and the highest) compression ratio can be maintained without loss of other characteristics essential of the stick. For example, the decrease in the size of the opening is minimal because the web prevents the compressed stick from growing radially inwardly.

However, if extreme elements of longitudinal restraint were used with a soulless stick, immediately after unloading, the initial compression ratio, which is the highest, would be retained, but additional inward growth would occur. of opening, this growth exceeding that occurring in the absence of any extreme longitudinal restraint. Since the user uses the smallest possible pleating mandrel to obtain optimal results (for the reasons indicated above), in all likelihood the additional internal radial growth would result in an opening whose size would be too small to allow an adjustment on the intended tamping mandrel.

 More particularly, FIG. 12 shows that, based on a comparison of the compression ratio values after 7 days for a fiber reinforced envelope article of size between 43 and 60, without a core and with a core (the two lower curves), the smallest improvement is obtained with the size envelope 43 and, in this case, the difference is about 78 minus 60, an increase of the compression ratio of about 30% the use of the article with soul.

The greatest improvement is achieved with the size envelope 60 and in this case the difference is 129 minus 79, or about a 63% improvement in the compression ratio using the core article. The theoretical maximum improvement, based on the comparison of the 7-day compression ratio of an article without a core (lowest curve) with the highest initial compression ratio (dotted line curve, to the upper part), is substantially larger. For example, with a size envelope 43, the difference is 97 minus 60, a compression ratio 62% higher, and with the size envelope 60, the difference is 146 minus 79, or about 85%.

A comparison of the compression yields and the compression ratios for the coreless and coreless fibrous shell articles of sizes 43, 47 and 60, as described in Example 11, is as follows:
R = ikment of compression (and coopression report)
Tille of the envelope Without soul (7 days) With soul (7 days) With soul (initial)
43 0.54 (60) 0.74 (78) 0.78 (82)
47 0.53 (66) 0.76 (95) 0.81 (102)
60 0.45 (79) 0.75 (130) 0.85 (147)
FIG. 13 shows that, based on a comparison of the compression ratio values after 7 days for the 70-100 fiber-reinforced envelope article, without core and soul, the improvement in Compression ratio is lower than that obtained with the size envelope 43-60, but it remains important.

The smallest improvement is obtained with the envelope of size 80 and in this case, the difference is 166 minus 154, or about 8 t. The theoretical maximum improvement, based on a comparison of the compression ratio, after 7 days, of the soulless article with the highest initial compression ratio for the size 80 envelope, is 180 minus 154, about 17 o.

A comparison of the compression yields and the compression ratios for the coreless and core pleated fibrous shell articles of sizes 70, 80 and 100, as described in Example XI, is as follows:
Compression efficiency (and compression ratio)
Envelope size Without soul (7 days) With soul (7 days) With soul (initial)
70 0.66 (129) 0.77 (141) 0.82 (150)
80 0.63 (154) 0.71 (166) 0.77 (180)
100 0.50 (167) 0.59 (187) 0.70 (220)
While consistency is also important with fiber-reinforced cellulosic casings, it does not cause such serious problems as those encountered with unreinforced, small-diameter cellulosic casings. This is partly because the former are by their nature, more resistant because of the presence of the fiber reinforcement, but also the differences presented by the tamping apparatus used for each of these envelopes.

 The small diameter cellulosic casings are usually stuffed with a fully automated, high speed machine in which the next stick to be used is automatically advanced to the stuffing position when the previous stick is exhausted. Poor consistency can cause stick rupture, which can lead to breakage or tearing of the envelope during insertion or rotation of the automated tamping mandrel. In this case, a large amount of food emulsion is spread around the machine before it can be stopped, and a long downtime is required to clean and remove the broken envelope.

 On the other hand, with large diameter fibrous casings, the speed of the machine is usually lower and the next stick is manually positioned for use by the operator. In case of breakage of the envelope (which is less likely due to the presence of fibrous reinforcement), the machine can be stopped before a significant amount of food product has passed, and the downtime is more short.

EXAMPLE XII
Before the discovery of the invention, the firm
Union Carbide Corporation has developed and marketed a machine, the "SHIRMATIC model 405" sizer, for filling whole boneless hams in fibrous-reinforced, large diameter cellulosic casings of the type previously described. This machine is designed to use a pleated casing with a calibration disc inserted into an unfolded end of the pleated clubless stick. At the beginning of the design of the machine, the need for a stuffing mandrel having an opening of maximum dimension was recognized, as was the limitation imposed on the mandrel dimension by the maximum opening that the formed stick could have. by the pleated casing.To obtain a mandrel of maximum size, the wall of the mandrel was reduced to the minimum acceptable thickness from the point of view of resistance, the length of the casing had to be undesirably reduced from 60 m to 45 m, and the pleating conditions were optimized to obtain the greatest possible opening.

In addition, the thickness of the wall of the tension sleeve and the clearance on the stuffing mandrel have necessarily been undesirably reduced to the minimum allowable values.

 The result of these efforts is the obtaining of the most advanced pleating technique currently possible and the use of a stuffing mandrel of 85.73 mm internal diameter. The calibration machine of the "SHIRMATIC Model 405" type of origin, as sold, is described in detail in Belgian Patent No. 888,526. A large number of these machines have been set up in meat packaging plants. , but they prove to be unsatisfactory in most applications. It has been observed that the extreme elongation of the pieces of ham as they pass through the mandrel, then their "messy positioning" when stuffing them inside of the envelope cause a displacement of the superficial fat towards the inside of the wrapped and stuffed hams, and give a bad disposition of the grain of the muscular fibers. The meat packing companies consider that this machine does not give the results equivalent to those obtained with the manual stuffing and the commercialization tests of the "SHIRMATIC model 405" machines have been momentarily suspended.

 Laboratory tests were then conducted on larger tamping mandrels and unfolded envelopes. These tests conclusively demonstrate that a larger mandrel solves the problems encountered with the "SHIRMATIC model 405" type machine, and that hams produced with a larger size tamping mandrel are of equally good quality. than those produced by manual stuffing.

We then began to develop the high-density pleated casing stick and core object of the invention. Development work has shown that the use of the high-density pleated-casing stick and core according to the invention as a stuffing mandrel results in an increase in the internal diameter of the mandrel to 95.25 mm. Part of this increase in the size of the mandrel is due to the removal of the tensioning sleeve of the "SHIRMATIC model 405" type machine. The tension sleeve is replaced by a tilting retaining device as described in the United States patent application.
United States of America No. 261 313, filed May 1, 1981.

 The result of these modifications made to the "SI-lIR.NEATIC Model 405" type calibration machine is an increase in the size of the mandrel, for a size 10 fibrous casing, of increasing its inner diameter by 85.73. mm to 95.25 mm. This corresponds to a diameter increase of 9.5 mm, a gain of 11.1%. This increase in diameter therefore results in an effective increase in the internal section of the stuffing mandrel by 23.5%. 7.5% of this 23.5% increase in mandrel section can be attributed to the elimination of the tension sleeve used in the prior art and 16.02 can be attributed to the use of the pleated product at high density and core according to the invention.

 In addition, by modifying the stuffing mandrel and using the shell and core stick in this manner, it is possible to increase the compression ratio of a size 10 fibrous casing from about 78 to about 100. 130, which corresponds to an increase of 67%. In addition, the compression yield is increased from 0.39 to 0.76 and the length of the casing is raised from 45 m to 75 m. This modification of the stuffing system is applied to the machine of the type "SHIRMATIC model 405H". Example I herein is an illustration of a core fibrous wrap article used in a machine of this type.

 This example also illustrates the preferred embodiment of the core article according to the invention, in which, on the basis of a comparison of the opening dimensions, it appears that the core has an opening dimension of at least as large as the size of the inner opening of the envelope if the latter was pleated and strongly compressed under the same conditions of pleating and compression, without soul, and at the same compression ratio. In particular, with a size 10 fibrous casing, the modified machine ("SHIRMATIC model 405H") with the core article uses a core having an aperture of 95.25 mm in size, while the inner dimension of the aperture the pleated club without a core is approximately 92.08 mm when this stick is obtained by pleating and compression at a compression ratio of 78. The core used with this particular dimension envelope is formed of high density polyethylene and has a wall thickness of 1.575 mm.

 After completion of the modification program, the machine of the type "SHIRMATIC model 405H" was returned to the meat conditioners who were not satisfied with the original machine "SHIRMATIC model 405", and this new machine was accepted and is considered to be an important advance for jamming hams. Ten months after the introduction of the "SHIRMATIC model 405H" type machine, twenty of these machines are used industrially and most of these machines have been used on a regular basis in meat packaging plants. The machine "SHIRMATIC model 405" has now been withdrawn from the market for the reasons indicated above, and the remarkable success of the "SHIRMATIC Model 405H" machine can be clearly attributed, in large part, to the present invention.

 The invention, as described above, is therefore an important advance in this technical field. A longer pleated casing length for a given stick length allows longer continuous production runs. Increasing the stuffing yield gives a more advantageous combination of a high compression ratio and a large opening dimension, which can maintain or improve the packing characteristics while allowing continuous production runs to be extended. . The invention completely eliminates the problems of consistency and growth of the stick, affecting so far the producers and users of small envelopes.The fact that the article according to the invention is moistened (avoiding imbibition) is particularly advantageous because the particularly high compression ratios can not be obtained with an envelope whose imbibition is provided by the user before stuffing. Indeed, the tight folds would oppose the introduction of water into the wall of the envelope and proper imbibition could be obtained, a period of time acceptable from the commercial point of view.

 It should be noted that the comparison between the inner circumferences of the crimped and press-enveloped article openings, with core and without core, should be made at least approximately one week after manufacture.

 It goes without saying that many modifications can be made to the article described and shown without departing from the scope of the invention.

Claims (32)

 Coated coherent article, characterized in that it comprises a tubular core (31) and a wetted cellulosic food wrap length (17) having a moisture content of at least about 13% of the total weight of the envelope, this length being pleated and strongly compressed on the core, at a high compression ratio and at a compression efficiency not falling below about 0.50, the ratio and the compression efficiency also being respectively greater to those of the same length of shirred and highly compressed casing, under the same conditions of pleating and compression, but without the lameness, so as to generate a high expansion force towards the inside of the envelope, eg, core being rigid enough to resist deformation and reduction of the size of its opening under the effect of the high expansion force exerted inwardly of the envelope.  2. Article according to claim 1, characterized in that the compression yield is not less than about 0.60.  3. Article according to claim 1, characterized in that the casing contains a fibrous reinforcement and has a moisture content of the order of about 16% to about 35% of the total weight of the casing.  4. Article according to claim 1, characterized in that the envelope has, in the inflated state, a diameter of between about 3.8 cm and about 9.9 cm, in that the outer diameter of the tubular core is from about 2.54 cm to about 5.08 cm, and in that the compression ratio of the unpleated length to the pleated length of the shroud is from about 50 to about 360, the tubular core being in particular having a wall thickness of between about 0.10 cm and about 0.15 cm.  5. Article according to claim 1, characterized in that the diameter of the envelope in the inflated state is less than 3.6 cm and the moisture content of the envelope is between about 14% and about 18 t of the total weight of the envelope.  6. Article according to claim 1, characterized in that, on the basis of a comparison of the fall adjustments, said core has an inner opening whose size is at least as large as that of the inner opening that the same envelope would have if it were creased and strongly compressed, under the same conditions of pleating and compression, without said core, said envelope can in particular be a non-reinforced cellulosic envelope, of small size, having a diameter in the inflated state of less than about 40 mm, the compression ratio being in particular equal to at least 100.  7. Article according to claim 1, characterized in that the diameter of the envelope in the inflated state is between about 10.2 cm and about 13.44 cm, in that the outer diameter of the tubular core is between about 7.6 cm and at least about 12.7 cm and in that the compression ratio of the length of the unpleated envelope to the pleated casing length is from about 100 to about 190; tubular core may in particular have a wall thickness of between about 0.127 cm and about 0.19 cm.  8. Article according to claim 1, characterized in that the thickness of the wall of the tubular core is at least about 0.05 cm.  9. Article according to claim 1, characterized in that the tubular core is made of high density polyethylene or polyvinyl chloride.  10. Article according to claim 1, characterized in that the compression ratio is not less than about 70.  An article according to claim 1, characterized in that the compression ratio is not less than about 70 and the compression yield is not less than about 0.60.  12. Article according to claim 1, characterized in that the diameter of the envelope in the inflated state is between about 6.6 cm and about 9.9 cm, in that the outer diameter of the tubular core is between about 5.08 cm and about 7.62 cm and in that the compression ratio of the unpleated length to the pleated length of the shell is between about 100 and about 200, the tubular core being able to have a wall thickness of between about 1.016 and 1.905 mm.  13. Article according to claim 1, characterized in that the casing is a small unreinforced cellulosic casing, having a diameter, in the inflated state, of between about 12.70 and about 38.10 mm, having an inside diameter opening which is at least 40% of the diameter of the envelope in the inflated state, and a core having a thickness of between about 0.254 and about 1.270 mm, the compression efficiency being at least 0.60 .  14. Article according to claim 13, characterized in that the compression ratio is at least 100.  15. Article according to one of claims 13 and 14, characterized in that the inner diameter of the opening of the core is equal to at least 50% of the diameter of the envelope in the inflated state.  16. Article according to claim 13, characterized in that the compression ratio is at least 120.  17. Article according to claim 13, characterized in that the diameter of the envelope in the inflated state is about 15.5 mm, the compression ratio is greater than 80 and the fall adjustment is from minus 9.14 mm, or in that the diameter of the envelope in the inflated state is about 18.5 mm, the compression ratio is greater than 98 and the fall adjustment is at least 10.41 mm, or in that the diameter of the envelope in the inflated state is approximately 21.1 mm, the compression ratio is greater than 100 and the fall adjustment is from minus 12.45 mm, or in that the diameter of the envelope in the inflated state is about 22.6 mm, the compression ratio is greater than 130 and the fall adjustment is at least 13.46 mm.  18. A method of manufacturing a pleated and highly compressed envelope article comprising a core, characterized in that it consists in using a length of cellulosic food casing (17) having a moisture content of at least about 13. % of the total weight of the casing, sliding the inner circumferential surface of the cellulosic food casing length on a first end of a mandrel (13) having a reduced diameter section at its second end, pleating the length cellulosic food casing on the mandrel, to use a hollow core (31) arranged coaxially and contiguously to the end portion of reduced diameter of the mandrel, this core being sufficiently rigid to withstand the deformation and reduction of the size of the mandrel; its opening under the effect of an expansion force acting towards the inside of the envelope as a result of the compression of this envelope, to move the the casing length is pleated on the mandrel to pass it over the outer surface of the coaxially disposed core, and to compress the length of pleated casing on the core at a high compression ratio and efficiency, so as to generate said expansion force exerted inwardly of the envelope.  19. The method of claim 18, characterized in that the compression efficiency is not less than 0.50.  20. The method of claim 18, characterized in that the compression ratio is at least 70.  21. The method of claim 18, characterized in that the compression ratio is at least 70 and the compression yield is not less than 0.60.  22. Method according to claim 21, characterized in that the compression ratio is at least 100, the food casing being a small diameter cellulosic casing, without fibrous reinforcement, and the inside diameter of the opening of the casing. soul being equal to at least 50 z of the diameter of the envelope in the inflated state.  23. The method of claim 22, characterized in that the compression ratio is at least 120, the food casing being a cellulosic casing of small diameter, without fibrous reinforcement, and the inner diameter of the opening of the soul being at least 40% of the diameter of the envelope in the inflated state.  24. A method of manufacturing a folded and highly compressed envelope article with a core, characterized in that it consists in using a length of cellulosic food casing (17) having a moisture content equal to at least about 13%. of the total weight of the casing, sliding the inner circumferential surface of the cellulosic food casing length over a first end of a mandrel (13), pleating and compressing said cellulosic food casing length on the mandrel, using a hollow core (31) which is rigid enough to withstand deformation and reduction of the dimension of its opening, by the effect of an expansion force exerted to the inside of the casing as a result of the compression of this envelope, and linearly moving the length of pleated and compressed envelope to pass from the second end of the mandrel to the outer surface of the core a to establish a high compression ratio and efficiency to thereby generate said expansion force exerted inwardly of the envelope as the opening of the pleated rod contracts.  25. A method of manufacturing a pleated and highly compressed envelope article with a core, characterized in that it consists in using a length of cellulosic food casing (17) having a moisture content of at least about 13%. of the total weight of the casing, sliding the inner circumferential surface of the cellulosic food casing length over a first end of a mandrel (1), pleating said length of cellulosic food casing on the mandrel, to be used a hollow core (31) rigid enough to withstand the deformation and reduction of the dimension of its opening under the effect of an expansion force exerted to the interior of the envelope as a result of the compression of the latter, to move the pleated casing length of the second end of the mandrel to the outer surface of the core, and to further compress the length of pleated casing on the core to a ratio and a high compression efficiency, so as to generate said expansion force exerted inwardly of the envelope.  26. The method of claim 25, characterized in that the core is supported by a second mandrel, the pleated envelope may in particular be transferred to the core and the second mandrel.  27. The method of claim 25, characterized in that the pleated cellulosic food casing length, supported by the mandrel, is brought into a second position before being moved from the second end of the mandrel to the core.  28. A method of manufacturing a folded and strongly compressed article with a core, characterized in that it consists in using a length of cellulosic food casing (17) having a moisture content of at least about 13% of the product. total weight of the envelope, to use a hollow core (31) rigid enough to withstand the deformation and reducing the size of its opening under the effect of an expansion force exerted inwardly of the envelope as a result of said compression, using a mandrel (13) and longitudinally sliding the inner circumferential surface of the core on the outer circumferential surface of the mandrel, longitudinally sliding the inner circumferential surface of the length of the mandrel (13); cellulosic food casing on the outer circumferential surface of the core, to pleat the length of cellulosic food casing on the core and the mandrel, to be compressed the cellulosic food casing length pleated on the core to a high compression ratio and yield, so as to produce said expansion force exerted inwardly of the casing, and to slide longitudinally the article with pleated envelope and strongly compressed, with core, to disengage it from the mandrel.  29. A method of manufacturing a pleated and strongly compressed envelope article with a core, characterized in that it consists in using a length of cellulosic food casing (17) having a moisture content of at least about 13%. of the total weight of the casing, sliding the inner circumferential surface of the cellulosic food casing length over a first end of a mandrel (13), pleating the cellulosic food casing length on the mandrel, compressing the shirred envelope length on the mandrel to a high ratio and compression efficiency, using a hollow core (31) rigid enough to withstand deformation and reduction of the opening dimension of the soul under the effect of an expansion force exerted inwardly of the envelope as a result of the compression of the latter, and to longitudinally slide the length of pleated envelope and comp to move it from the first end of the mandrel and pass it over the outer circumferential surface of the core to achieve a high compression ratio and efficiency and thereby to generate said expansion force exerted on the outer circumferential surface of the core. inside of the envelope when the opening of the pleated stick contracts.  30. A method of manufacturing a pleated and highly compressed envelope article with a core, characterized in that it consists in using a length (17) of cellulosic food casing having a moisture content of at least about 13%. of the total weight of the casing, sliding the inner circumferential surface of the cellulosic food casing length over a first end of a mandrel (13), pleating the cellulosic food casing length on the mandrel, to be used a hollow core (31) rigid enough to withstand the deformation and reduction of the dimension of the opening of the core under the effect of an expansion force exerted inwardly of the envelope by following the compression of the latter, to move the length of pleated cellulosic food casing, supported by the mandrel, to a second position, to pass the pleated casing length of the first extrem the core on the outer surface of the core, and further compressing the pleated casing length on the core to a high compression ratio and efficiency, so as to generate said expanding force towards the inside of the envelope.  31. The method of claim 30, characterized in that the core is supported by a second mandrel, the partially compressed envelope may in particular be transferred to the core and the second mandrel.  32. A method according to any one of claims 24, 25 and 30, characterized in that the core is disposed coaxially and contiguously to the second end of the mandrel.