NL8602141A - METHOD AND APPARATUS FOR MANUFACTURING THERMALLY INSULATED PIPE TUBES. - Google Patents

Description

* ·>% VO 8336

Title: Method and device for manufacturing thermally insulated pipe conduits.

The invention relates to a method and an apparatus for the continuous production of thermally insulated pipe tubes with a protective plastic jacket for the transport of liquid or gaseous, heated or cooled media, wherein said pipe pipe may optionally be used with respect to the as a separating agent-working foil surrounded with foam and provided with a protective plastic jacket.

Methods are known both for the continuous and discontinuous production of thermally insulated conduit pipes, which are provided on the outside with a protective jacket of plastic.

Several of the known, continuous methods consist in passing the spaced-down conduit tube along with a plastic sheath serving as a protective sheath through a stationary molding tube, thereby joining and welding the edges of the plastic wall to that plastic foil hose takes place just before insertion into the stationary molding tube. The plastic mixture to be foamed is usually applied to said plastic film tape just before the joining and welding together of the overlapping edges of the plastic film tape formed into plastic film hose. During the passage through the stationary molding tube, the foaming of the annular space between the conduit tube and the tubular protective outer jacket then takes place. Optionally, in this method, instead of the plastic foil hose, a copolymer-coated aluminum foil can be used and the protective jacket can be extruded through the stationary molding tube by means of an extruder after passing the foam-lined conduit tube ( DE-OS 3 307 865).

However, these continuous processes have not found practical application in relatively large diameter conduit pipes, since the frictional forces between the outer jacket and the stationary molding tube, caused by the foam pressure occurring, are too great to pass rapidly through the stationary molding tube, even if additional lubricant is introduced between that outer jacket and the stationary molding tube.

1602141

ΐ Q

In place of these continuous processes, therefore, in practice, especially for conduit pipes with lengths of 6 to 12 meters and with diameters of 20 to 60 mm, is applied in discontinuous processes, the pipe conduit being first provided at predetermined distances with -5 foam permeable spacers and a relatively thick plastic hose is pulled over it. The assembly thus prepared is then gradually foamed in an oblique position. The thickness of the plastic hose in this method depends on the foam pressure that occurs, since it has the task not only to form the outer jacket, but also to function as a "shape". That plastic hose must therefore be so strong that it can absorb the foam pressure that occurs. A drawback of this method is therefore not only the necessary application of the thick plastic hose, but also the fact that no uniform foam is produced by the foaming in an inclined position and, moreover, that foam has a relatively high volume weight. In addition, the discontinuous process is not economical.

The object of the invention is therefore to provide a method and an apparatus, in which it is possible to produce conduit pipes, and also conduit pipes with a relatively large diameter, economically continuous mat, while at the same time saving material for the outer jacket and forming of uniform, low-density foam in the thermally insulating active layer.

This object is achieved according to the invention in that (a) the foam pipes to be surrounded by foam are continuously inserted centrally in an axial direction into a tubular cavity formed by a double-mold block chain belt installation while simultaneously surrounding said pipe pipes with foam. wherein (b) the plastic mixture to be foamed is adjusted such that the appearance until the time when the conduit pipe would buckle or sag due to its own weight has hardened so far and performs a function supporting that conduit pipe, and (c) on that foamed conduit tube, after exiting the double-form block chain belt installation in an optionally cooled and evacuated calibrator, a high volume weight foamed plastic jacket is extruded through an annular nozzle.

The double-form block chain belt system used according to the invention is known per se and serves, for example, for the 8802141. '-3- ν' * tinu manufacture of longitudinally slotted foam insulated pipes according to DE-AS 1 266 485, respectively for the continuous production of two hinged, blown, foamed, connected by means of an outer foil hinged half house shells according to 5 DE patent 2 503 425.

Particular difficulties were encountered in the continuous manufacture of the longitudinally slotted foam insulated pipes according to DE-AS 1 266 485, the attachment of the core, which extends over the full length of the mold channel formed by the two movable mold block chains, and which is necessary to form the interior of the foam insulated pipe. Namely, it has been found that even when the core is tightly clamped at both ends, nevertheless the pressure generated in the molding channel by the foam is so strong that it cannot be centered over its full length. Therefore, in order to avoid such deviations, the core was additionally provided over its entire length with a supporting mounting plate, which extends radially into the molding channel between the opposed molding blocks.

The same with regard to the eccentricity of the core also applies to another known installation, which is provided with a fixed doom as the inner core, which is only attached to the run-in end of the installation and freely extends into the free-standing or circumferential outer shape. Here too, the mandrel clamped only on one side has only insufficient stability to absorb the compressive forces occurring during foaming without effect. In this regard, reference is made to the explanations in DE patent 2 503 425, cited above, column 3, lines 49 and following. Because of the problem of drifting away from the doom, in another known installation, according to DE-AS 2 165 584, the proposal is therefore made to check the deflection of the mandrel by means of a laser beam and by controlling control elements. apply a correction to reverse that diversion. By means of this auxiliary device, however, it is difficult to achieve flawlessly accurate strips of the fixed inner core (mandrel) with the hardline, not to mention that the entire installation is extremely complicated and susceptible to disturbances.

In view of the experience gained with such double-form block chain belt systems in connection with the production of longitudinally slotted 5502141 foam insulated tubes, it must be regarded as extremely surprising that the invented method using a double-form block chain belt installation with foam plastic insulated conduit pipes, wherein even the conduit pipes 5 with very large diameters are concentrically fixed in the foamed plastic material without the use of spacers in terms of their location.

The continuous process possible through the use of the double-form block chain belt installation allows the conduits to be continuously surrounded by foam, which has the advantage that the full-length foam envelope has a homogeneous cell pattern without bubbles at low volume weight whereby not only a uniform mechanical strong but also improved lambda values are obtained. Moreover, by means of the extruder disposed behind the double-mold block chain belt installation 15 with associated vacuum calibrator, it is also possible economically to realize the foamed plastic sheath with a high density and smooth outer skin in the correct required shape. Moreover, the protected plastic jacket can be made considerably thinner in the invented method than in the discontinuous method outlined in the preamble, since the pressure occurring during the formation of the thermally insulating foam layer no longer needs to be absorbed by the plastic jacket. Thus, when the invented method is used, the functions of the plastic jacket are limited to diffusion density and protection against damage during transport and when laying the conduit pipes. The foamed, protective jacket reduces weight and price and increases flexibility. Preferably, said jacket consists of a foamed polyethylene, polypropylene, polyvinyl chloride or the like and preferably has a volume weight of 500 to 800 kg / m3.

Moreover, since the invented installation is designed in such a way that the conduit pipes are automatically concentric to the outer jacket - that is, exactly in the middle - all / resp.

spacer holders, such as are necessary in the prior art methods, are dispensed with. This has as a further advantage that the large number of cold bridges is eliminated, whereby the thermally insulated conduit pipe manufactured according to the invention is considerably improved and cheaper.

S ö 0 2 1 4 1 ** £ -5-

The invented method is suitable for all thermally insulated pipe tubes, such as, for example, copper, steel or plastic pipes. With copper or plastic pipes, they can be used with relatively small diameters, for example with diameters of 22 mm from the roll. on which they are supplied in lengths of 50 meters or more, are fed practically endlessly after straightening in the desired manner to the double-form block chain belt installation and, after applying the foam around it, and applying the plastic jacket again on a role to be wound up.

In the case of plastic pipes of relatively large diameter, they are best manufactured by extrusion directly for the device used according to the invention, so that the manipulation with the handling of the pipes is eliminated. After leaving the device proposed according to the invention, the conduit tubes, which can no longer be wound up on a roll, are shortened in the thermally insulated conduit tubes of the desired length on a case-by-case basis.

Rigid pipes .., that is. say steel pipes or other metal pipes, are preferably used in pieces of 12 to 18 meters, which, just before insertion into the device proposed according to the invention, are connected to an "endless strand®" with special plastic sleeves and then practically also "endless", continuous with foam. - '- are surrounded and sheathed. After dismantling, those pipes are then separated from each other again with a special saw in the region of the sleeves, that is to say the pipe connectors. pipe connectors 25 are designed such that, after they have been removed when laying the thermally insulated pipe pipes, they release the pipe ends without foam insulation, so that the pipe pipes can then be sealed and durably bonded with conventional pipe connectors and subsequently insulated.

Any suitable plastic provided with so-called propellants or suitable starting components forming the plastic involved can be used to realize the thermally insulating foam layer.

Depending on the intended application, the foam of the thermally insulating layer can be more or less flexible or rigid. For example, the use of flexible foams is recommended in those cases where the "endless", thermally insulated conduit tubes are wound up on a roll after exiting the invented device. On the other hand, with rigid pipes it can be advantageous to apply a hard type of foam.

Suitable foams preferably include polyurethane foam, polyisocyanurate foam, polyolefin foam, in particular polyethylene or polypropylene foam or foam types of suitable copolymer isates thereof, as well as polystyrene foam.

When forming polyurethane foam, regardless of whether it is of flexible or rigid type, the use of a separating film is necessary, which, together with the conduit pipe, is introduced into the double mold block chain conveyor installation in such a way that the film is placed against the mold block. come to lie. The annular space between the separating foil and the conduit tube is then foamed full.

Any type of film can be used as the separating film, for example a film of paper, plastic or metal. In order to achieve a pure separation action, it is sufficient to use paper or plastic foil as a separation foil. However, if additional effects, for example a heat reflection or a vapor-proof coating, are desired, it is advantageous to use a metal foil, for instance an aluminum foil 20 coated on one side or on both sides with paper or plastic.

On the other hand, certain foam types, for example, foam types of polyethylene or polystyrene, can be operated without a separating film, since it may be sufficient if the mold block chains are treated with a conventional mold separating agent during the backflow. When one thereby works with mold block chains additionally cooled during the return run, when one proceeds in a suitable manner, one can even achieve that a relatively firm, largely homogeneous surface skin is obtained, so that possibly even the outer plastic jacket can be omitted.

The introduction of the mixture to be foamed into the annular space between the conduit tube and the separating foil or the mold block chains is effected in the usual manner, for example as described in DE-OS 3 307 865 cited in the preamble, by mixing the mixture to be foamed. on the separating foil before joining until the foil-35 hose is applied. Adjustment of the plastic to be foamed, preferably of components A and B for forming polyurethane foams, is effected such that already shortly after the entry of the 8302141 -7- '; of the separating film provided with the foam to be foamed in the double-form block chain belt installation, the foam fills the annular space between the pipe tube and the separating film and at the same time the pipe pipe is held concentrically by the foam which has now become load-bearing. The measures necessary for this are known to the person skilled in the art, or can be determined without difficulty.

If desired, one or more notification guides can be foamed in at a distance from the pipe tube 10 when applying the foam around the pipe tube. These reporting devices serve to report and locate the moisture that has penetrated into the foam layer.

The invented method, of course, also allows the simultaneous foaming of a number of conduit pipes insulated from one another, which are then surrounded by a common protective plastic jacket. Advantageously, in that case two conduit pipes will be accommodated in one protective plastic jacket and insulated from each other, the cross section of such an assembly being preferably not round but oval. This embodiment is used, for example, as a branch pipe from the main pipe to the consumers, so that the inlet and the outlet are housed in one unit, which makes it possible to reduce the transport and laying costs.

The invention will now be explained in more detail below with reference to the drawing with four figures, in which particularly preferred embodiments are shown, without however the invention being limited to those embodiments.

Figure 1 is a schematic top plan view of the core piece of the invented device;

Figure 2 is a schematic cross-section of the mold blocks (5a, 5b, 5ar, 5b ') forming the double-form block chain of the belt installation (5) according to the cutting line A-A in Figure 1?

Figure 3 is a cross-section of a thermally insulated pipe tube 7 according to the invention; and

Figure 4 is a cross-section of a pipe connector 12.

In Figures 1 to 4 and the figure description below, the reference numerals have the following meanings: 1. Conduit pipe 8602141 W “* Ïl · -8- 2. Stock roller for separating foils STS Separating foils 4. Foaming machine 5. Double form block chain belt installation 5 5a , 5b, 5a ', 5b' the y-mold block chain forming mold blocks 6. Vacuum-calibrated extruder 7. Thermally insulated conduit pipe 8. Mold channel formed by the mold blocks 5a, 5b 9. Frame for guiding the mold block chains 10 10. Thermally insulating foam layer 11. Foamed plastic jacket. 12. Pipe connector

In the figure 1 schematically shown double-form block chain-15 belt installation 5 is provided. two mold halves, which are longitudinally divided into separate mold blocks 5a, 5b, 5a ", 5b", and which conform at a corresponding speed along one. be placed in a straight line. The individual molding blocks 5a, 5b form the necessary molding channel, pressed tightly together, and are diverted outside the production range as separate molding blocks 5a ', 5b' (see figure 2) on the guide frame 9 in a manner known per se and returned. The mold blocks 5a, 5b can be exchanged with a view to adaptation to the desired diameter of the conduit pipe, or of the thermally insulating foam foam to be molded to be formed.

According to a preferred embodiment according to the present invention, for example, a flexible copper tube or a flexible plastic tube is removed from a supply roll by means of a tube feeding and holding device supplied via a straightening tool to the double-form block chain belt installation 5 together with the Separating film 3 unwound from the separating film supply roll 2, wherein the separating film 3 is supplied with the foaming mixture to a foaming mixture before entering the double-mold block chain belt installation 5 by means of a foaming machine 4 and into a hose. is being formed. After leaving the double-mold block chain belt installation 5, the conduit pipe / device 35 provided with the foam layer 10 is passed through the extrusion 6 provided with the vacuum calibrating device, the actual foamed protective plastic jacket 11 having a high volume weight on the separating foil 3. is applied. The thermally insulated pipe tube 7 (see figure 3) thus completed is then 8 0 0 2 1 4 1 -ö.

-9 “wound on a transport roller and transported to its destination where that tube of the roller is laid out.

In accordance with another preferred embodiment of the present invention, rigid, rigid conduit tubes 1, especially conduit tubes of relatively large diameters in lengths from 6 to 18 m, preferably from 12 to 18 m. 1, not shown in FIG. 1, by means of a tube feeding and retaining device (also not shown) to the double-mold block chain belt installation 5 together with the separating foil 3 and the mixture to be foamed in the manner described in the foregoing. In order to ensure a continuous process, the conduit pipes 1 to be insulated are successively connected to each other by means of the pipe connectors 12 shown in Figure 4 and a thus-formed quasi-endless strand is passed through the double-form block chain belt installation 5-The pipe connectors 12, in terms of their outer and inner diameters, are adapted to the relevant conduit tube 1 and the desired thermally insulating foam layer 10. After leaving an vacuum calibrating device, the extruder 6 provided with the protective plastic jacket 11 is applied. pipe connector 12, not visible on the outside, sawed centrally by means of a controlled saw transverse to the longitudinal axis. The thermally insulated conduit tubes 7, which are thus separated again from each other, are fed to the packaging or bundling unit via an alloy frame. The cut pipe connectors advantageously remain connected to the thermally insulated conduit pipes 7 until the installation work is completed and are only removed from the conduit pipes shortly before the installation.

However, it is also possible, of course, to immediately separate the thermally insulated pipe tubes 7 from the vacuum calibrating device of the extruder 6 from the pipe connectors 12, so that these uncut sawed pipe connectors 12 are removed after removing the separating film 3 with plastic jacket 11 drawn around it. can be used over and over again. The thermally insulated conduit pipes 7 freed from the pipe connectors 12 can then, if desired, be provided with other protective caps for the transport up to the mounting.

A further advantage which the use of the pipe connection piece 11 according to the invention provides is to be seen in that after removal of the pipe connection piece 12 the pipe 8302141 is immediately

"W

-10 pipe ends for the later necessary, usual, durable and sealing pipe socket connection.

8602141

Claims (7)

Method for the continuous production of thermally insulated conduit tubes with a protective plastic jacket for the transport of liquid or gaseous, heated or cooled media, wherein said conduit tube, optionally using a film which acts as a separating agent with respect to the device 5 foam is surrounded and provided with a protective plastic sheath, characterized in that (a) the conduit pipes (1) to be surrounded by foam are continuously centered in a tubular cavity (8} formed by a double-form block chain belt installation (5) in axial direction is introduced while at the same time surrounding with foam, wherein (b) the plastic mixture to be foamed is adjusted such that the appearance until the moment when the conduit pipe (1) would buckle due to its own weight sag, as far as hardened and perform a function supporting the conduit pipe (1), and 15 (c) on the foam pipe conduit s (1) after it has left the double-mold block chain belt plant (5), with an optionally cooled, vacuum-calibrated extruder (6), a high-volume, foamed protective plastic sheath (11) by means of an annular nozzle extruded. Method according to claim 1, characterized in that before the foaming of the interspace between the conduit tube (1) and the mold blocks (5a, 5b) of the double-mold block chain belt installation (5), one enters into said double-mold block chain -band installation (5) insert a hose (3), preferably made of paper, of aluminum or plastic-coated aluminum foil or of plastic, into a hose, and only then foam the annular space between the pipe (1) and the separation foil (3) . Method according to claims 1 and 2, characterized in that the interspace between the conduit tube (1) and the separating foil (3) is filled with a starting mixture, which forms polyurethane foam. Method according to claims 1 and 2, characterized in that a polyolefin, preferably polyethylene or PVC, is provided with a propellant for the production of the foamed protective plastic jacket (11). Device for carrying out the method according to claim 8302141 s-V. -12- 1 to 4, characterized by a, per se known, provided with a foaming machine (4) double-form block chain belt installation (5), for the inlet of which is a pipe feed and holding device, possibly with a pipe straightening tool, and behind which the outlet is an, optionally cooled, vacuum-calibrated extruder (6) with an annular nozzle for manufacturing the foamed protective plastic jacket ( 11). Device according to claim 5, characterized in that the foam machine (4) is a two-component mixing machine for the production of polyurethane foam. 7. Thermally insulated conduit pipe (7), characterized in that the protective plastic jacket (11) located on the thermally insulating foam layer (10) consists of a plastic foam with a high volume weight and a smooth closed-cell surface. 8602141