DK165908B - METHOD AND APPARATUS FOR THE MANUFACTURE OF THERMALLALLY INSULATED CONNECTIONS - Google Patents

Description

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DK 165908B

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for the continuous manufacture of thermally insulated conduits with a plastic protective cap and for the transport of liquid or gaseous, heated or cooled media, wherein the conduit is foamed and provided with a plastic protective cap, optionally using a foil which acts as a separator to the apparatus.

Methods are known for both continuous and discontinuous production of thermally insulated conduits which are externally provided with a plastic protective cap.

Such known continuous methods may be based on passing the spacer wiring 15 together with a plastic foil hose serving as a protective sheath through a stationary mold tube, whereby the joining and joint welding of the plastic strip gutter to the formation of the plastic foil tube takes place shortly before insertion into the the stationary mold tube. The foamed plastic mixture is usually applied to the 20 plastic foil tape which is to form the plastic foil tube shortly before joining and welding the overlapping edges of the piast foil tape. During passage through the stationary mold tube, the foaming takes place within the annular space between the conduit and the tubular outer protective casing. Optionally, in this method, instead of the plastic film tube, an aluminum foil coated on both sides may be used and the protective cap extruded by an extruder after passing the foamed conduit through the stationary mold tube (DE 30 Publication No. 33 07 865).

In practice, however, this continuous process has not been able to penetrate in the case of large diameter conduits, since the frictional forces between the outer sheath 35 and the stationary tube, depending on the foam pressure in question, are too large to ensure a rapid passage through the stationary molding tube, although between the outer casing and the stationary molding tube a further idling agent is applied.

DK 165908 B

2 In relation to this continuous method, therefore, in practice a discontinuous method is used, particularly in the case of conduits having lengths of from 6 to 12 m and diameters of 20 to 60 mm, in which method the conduit is first provided with foam-permeable by spacers at specified distances and coated with a relatively thick plastic hose. The article thus prepared is then gradually filled with foam in an oblique position. In this way, the thickness of the plastic hose adjusts to the foam pressure in question, since it not only has the task of forming the outer sheath, but at the same time serves as a "shape". Therefore, the plastic hose must be so strong that it can absorb the particular foam pressure. Therefore, it is not only a disadvantage of this method that a thick plastic hose is necessarily used, but also that, due to the foaming in the inclined position, no uniform foam is formed and that the foam additionally has a relatively high volume weight . In addition, the discontinuous approach is not economically appropriate.

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It is, therefore, an object of the invention to provide a method which allows conduits, even those of large diameter, to be continuously manufactured in an economically convenient manner while simultaneously saving material to the outer sheath and forming a uniform low density foam. in the thermally insulating acting layer.

This is achieved according to the invention by: (a) in a manner known per se, the pipes to be foamed are fed axially in a axial direction continuously and centrally into a tubular cavity formed by a double molded block bonding system during simultaneous foaming, whereby (35) the foamy plastic mixture is set so that it is most recently cured so as to be able to carry the conduit when the conduit would break or hang due to its own weight;

DK 165908B

3 (c) and on top of the foamed conduit after leaving the dual mold block chain assembly with an optionally cooled vacuum calibrated extruder extrudes a foamed high volume weight plastic protective cap 5 by means of a ring nozzle.

The dual mold block chain belt system used according to the invention is known per se and serves e.g. for the continuous production of longitudinally split foam insulation pipes according to DE-presenting specification 12 66 485 or for continuous production of two by means of an outer foil in a hinged manner interconnected collapsible half foam shells of DE patent no.

25 03 425.

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In the continuous method of producing longitudinally split foam insulating tubes according to German Patent Specification No. 12 66 485, particular difficulties exist in retaining the core extending over the entire length of the mold channel formed by the two movable mold block chains. , and which is necessary for the formation of the foam insulation tube inner space. Namely, it has been found that even when the core is firmly clamped at both ends, the pressure produced by the foam within the channel is so great that the core cannot be centered over its entire length. Therefore, to avoid such deviations, the core over its entire length was further provided with a supporting holding plate which protrudes radially into the mold channel between the mold blocks placed opposite each other.

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The same phenomenon with respect to the displacement of the core also applies to the other known plant, which comprises a fixed mandrel, such as the inner core. This mandrel is attached only at the inlet end of the system and projects freely into the fixed or circumferential outer mold. Here, too, only the one-sided clamped mandrel does not exhibit sufficient stability to absorb the pressure associated with the foam without

DK 165908 B

4 offset. Reference is made in this connection to the embodiments described in the aforementioned German patent specification No. 25 03 425, column 3, line 49 et seq. Therefore, because of the problem of the aforementioned mandrel displacement, it is proposed by another known plant according to DE-presenting specification 21 65 584 that the displacement of the mandrel is controlled by a laser beam and a rectification is made via control and control elements. However, with the aid of this auxiliary device only impeccable alignment 10 of the stuck inner core (mandrel) is obtained, except that the whole system is very complicated and has a high tendency to exhibit problems.

In view of the experience gained with such dual mold block chain strip systems in connection with the manufacture of longitudinally split plastic insulation pipes, it is extremely surprising that in the inventive method, pipes insulated with foam are obtained using a double molded block chain tape assembly, whereby even the 20 large diameter conduits are fixed in place concentrically within the foam, even without the use of spacers.

The continuous method possible with the use of the double mold block chain system ensures a continuous foaming of the conduits, which at the same time has the advantage that the foam shell over its entire length has a homogeneous cell image without blisters at low volume weight, thereby not only being achieved a uniform mechanical strength, but also better λ values.

In addition, by means of the extruder coupled to the double mold block chain system with the associated vacuum calibration device, it is possible to provide the foamed plastic protective sheath with high density and smooth outer coating in an economically suitable manner. In addition, in the process according to the invention, the plastic protective sheath can be formed substantially thinner than the discontinuous method initially mentioned, since the pressure,

DK 165908B

5 which occurs in the formation of the thermal in the soldering p1 ast 1 ag, no longer needs to be captured by the plastic sheath. Thus, the functions of the plastic sheath in the method according to the invention are reduced to diffusion density and protection above 5 for damage during transport and deposition. The foamed protective sheath reduces weight and price and increases flexibility. It preferably consists of a foamed polyethylene, polypropylene, polyvinyl chloride or similar material and preferably has a volume weight of from 500 to 800 kg / m 3.

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Furthermore, since the apparatus is designed so that the conduits are automatically placed concentrically - that is, centrally - relative to the outer sheath, any spacers or centering holders which are otherwise required by the method of the prior art can be avoided. In this way, the additional advantage is obtained by avoiding the many cold bridges, whereby the thermally insulated conduit produced by the method according to the invention is further improved and cheaper.

The method of the invention is suitable for all conduits which are to be thermally insulated, such as e.g. copper, steel or plastic pipes. In the case of copper-plastic pipes, these may, in the case of smaller diameters, e.g. at diameters of 22 mm, practically 25 are infinitely supplied to the double mold block chain belt assembly from the roll, whereupon they are delivered in lengths of 50 m or more, after appropriate straightening and after the foaming and placement of the plastic sheath, they can again wound up on a roll.

30 In the case of large diameter plastic pipes, these are best provided directly in front of the apparatus by extrusion to avoid handling of the pipes. After leaving the apparatus, the conduits which are no longer wound onto a reel are cut into the thermally insulated conduits of the desired length at all times.

In the case of rigid pipes, e.g. steel tubes or other metallic tubes, pieces of length are preferably used

DK 165908 B

These pieces are connected shortly before insertion into the apparatus with special plastic sleeves to an endless string, and are then virtually endlessly and continuously foamed and provided with a sheath. After application of the sheath, the pipes are separated by a special saw within the area of the sleeves, ie. rørforbindelsesstykkerne.

The pipe connectors are arranged so that after their removal by the laying of the thermally insulated conduit they release the pipe ends without foam insulation so that the conduits can be connected tightly and permanently to one another by known pipe connectors and then insulated.

For the provision of the thermally insulating foam layer, any suitable plastics material or propellant or similar starting components which form the plastics material in question may be used.

Depending on the application, the foam in the thermally insulating layer may be more or less flexible or rigid. Eg. the use of flexible foams is recommended in cases where the endless thermally insulated conduits are wound on rollers after leaving the apparatus. In contrast, in the case of rigid pipes, it can be advantageous to use a hard foam material.

Suitable foams preferably include polyurethane foams, polyisocyanurate foams, polyolefin foams, especially polyethylene or polypropylene foams or foams of suitable copolymericates thereof, such as polystyrene foams.

In the provision of polyurethane foam materials, be they flexible or rigid, it is necessary to use a separating foil which, together with the conduit, is inserted into the double mold block chain assembly so that it arrives

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7 systems against the mold blocks. The annular space between the separation foil and the conduit is then filled with foam.

As a separating foil, any type of foil such as e.g. of paper, plastic or metal. In order to achieve a pure separation effect, it is sufficient to insert paper or a plastic film as separation film. However, if additional effects are desired, such as a heater reflection or a vapor barrier, it is advantageous to use a metal foil, e.g. an aluminum foil coated with paper or plastic on one or both sides.

On the other hand, in the case of certain types of foam, such as polyethylene or polystyrene foams, it is possible to work without a separation foil as it may be sufficient if the mold block chains during the reflux are treated with a known mold separating agent. In this connection, if you work with mold biochains, which are further cooled during return, certain methods 20 can even achieve a relatively firm and largely homogeneous surface skin, so that even the outer plastic protective jacket can be avoided.

The insertion of the foamable mixture into the annular space between the conduit and the separating foil and the form block chains, respectively, takes place in a known manner, e.g. as described in the German publication specification no.

33 07 865, placing the foamable mixture on top of the separation foil before joining it to the foil tubing.

The setting of the foamable plastics material, preferably components A and B, to form polyurethane foam fabrics takes place so that the foam fills the annular space between the conduit and the separation film, shortly after the separating film provided with the foamable mixture is formed. in the form of a hose, pass into the double mold block chain assembly, and at the same time the conduit is held concentrically by the foam which in the meantime

DK 165908 B

8 has been able to carry. The necessary measures are known to the person skilled in the art or can be obtained without difficulty.

5 If desired, one or more message conductors may be embedded at a distance from the conduit during the foaming of the conduit. These message conductors serve to detect and locate moisture that penetrates the foam layer.

The method according to the invention also enables several mutually insulated conduits to be simultaneously surrounded with foam, the conduits being in that case surrounded by a common plastic protective sheath. In this connection, it is particularly advantageous to place two conduits in a plastic protective sheath where they are insulated relative to one another, the cross section of such a connection structure being preferably non-circular but oval. This location is preferably used in connection with a branch line from the main line to the customers, so that in one unit both forward and reverse are arranged, thereby reducing transport and closing costs.

The invention is explained below with reference to FIG. 1-4, which show particular advantageous embodiments of the invention, and in which FIG. 1 is a schematic top view of the central part of an apparatus for carrying out the method according to the invention; FIG. 2 is a schematic diagram showing 5 forming mold blocks 5a, 5b,

5a ', 5b' in double form block chains, cut in section along line A-A

in FIG. 1, FIG. 3 is a section through a thermally insulated conduit 7 made by the method of the invention; and FIG. 4 shows a cross section of a pipe connection piece 12.

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9 In FIG. 1-4 and the subsequent embodiments, the reference numerals have the following meanings: 1 conduit 5 2 separating foil stock roll 3 separating foil 4 foam machine 5 double front block chain strip system 5a, 5b, 5a ', 5b1 mold blocks forming mold block thermocouple fiber 10 6 vacuum insulated conduit 8 is a mold channel formed by the parent blocks 5a, 5b 9 frame for guiding the mold block chains 10 thermally insulating foam layer 15 11 foamed plastic protective cap 12 pipe connector.

In the embodiment shown in FIG. In schematically shown double mold block chain assembly 5, two mold halves are provided which are divided into 20 single mold blocks 5a, 5b, 5a1, 5b 'longitudinally and which move at a uniform speed along a straight line. The individual mold blocks 5a, 5b form tightly pressed against each other the necessary mold channel and are redirected and returned in a manner known per se outside the manufacturing area as separate mold blocks 5a ', 5b' (see Figure 2) on top of the guide frame 9. The molding blocks 5a, 5b can be exchanged for adaptation to the desired diameter of the conduit or the thermally insulating acting foam casing to be provided.

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According to a preferred embodiment of the invention, e.g. a flexible copper tube or a flexible plastic tube from a supply roll by means of a pipe feeder and pipe retaining device through a straightening tool up to the double mold block chain belt assembly 5 together with the separating foil 3 wound by the separating foil feed roll 2 in which the separating foil feed roll 2 double mold block chain

DK 165908B

10 tape systems 5 are provided with a foamable mixture by the foam machine 4 and formed into a hose. After leaving the dual mold block chain strip system 5, the conductor tube 1 provided with the foam layer 10 is passed through the extruder 6 equipped with a vacuum calibration device, where on the separating foil 3 is placed the actual foamed plastic high-weight foam protective cap 11. The thus-finished thermally insulated conductor pipe 7 (see Fig. 3) is then wound onto a transport roller and brought to the point of application where it is laid out from the roller.

According to another preferred embodiment of the invention, rigid, non-flexible conduit 1, in particular those having large diameters and lengths from 6 to 18 m, preferably from 12 to 18 m, is guided from one of FIG. 1 not shown as a storage rack by means of a pipe and guiding device, not shown, also up to the double mold block chain belt assembly 5 together with the separating foil 3 and the foamable mixture in the manner described above. In order to ensure a continuous operation, the conduits 1 to be connected are connected by means of the lines shown in FIG. 4, and is passed as a strand similar to an endless strand through the double mold block chain band assembly 5. The tube connectors 12 are adapted to their internal and external diameters for the respective conduit 1 and the desired thermally insulating foam layer 10. After leaving the extruder 8 equipped with a vacuum calibration device and the insertion of the plastic protective cap 11, the outside of the invisible tube connector 11 is sawed 30 through the center across its longitudinal axis by a guided saw. The thermally insulated conductor tubes 7 thus separated are then supplied with a storage rack in a packaging or bundling unit. The cut-out pipe connection pieces conveniently remain connected to the thermally insulated conduit pipes 7 for the laying assembly and are removed only shortly before the installation of the conduit pipes.

Claims (4)

A method for the continuous manufacture of thermally insulated conductor tubes with a plastic protective cap and for transporting liquid or gaseous, heated or cooled media, wherein the method of the conductor tube is foamed and provided with a plastic protective cap, optionally using a foil acting as a separator. opposite the apparatus, characterized in that (a) the conduit (1) to be foamed is, in a known manner, perpetually axially directed and centrally inserted into a tubular cavity (8) formed by a double mold block chain belt assembly (5) during simultaneous foaming, whereby (b) the foamable plastic mixture is set so that it is most recently cured to support the conduit (1) when the conduit (1), due to its own weight, otherwise would crack or hang, DK 165908 B (c) and that on top of the foamed conduit (1) after leaving the double mold bl with a possibly cooled, vacuum calibrated extruder, a foamed plastic protective cap (11) 5 with high volume weight is extruded by means of a ring nozzle. Method according to claim 1, characterized in that before the space between the conduit (1) and the mold blocks (5a, 5b) of the double mold block-band system (5) is filled 10 with foam, a separating foil (3) is applied which the thread in the double mold block chain assembly (5) is formed into a hose, which preferably consists of paper or of an aluminum foil coated with plastic or paper, and that the annular space between the conduit (1) and the separation foil (3) is first filled thereafter with foam. Method according to claims 1 and 2, characterized in that the space between the conduit (1) and the separation foil (3) is filled with foam by means of an initial mixture 20 which forms a polyurethane foam. Process according to claims 1 and 2, characterized in that a foamed plastic protective cap (11) is used for the production of the foamed polyolefin, preferably polyethylene, or polyvinyl chloride. 30 35