CH671543A5 - - Google Patents

Description

DESCRIPTION

The present invention relates to a method and a device for the continuous production of thermally insulated conduits with a protective plastic jacket for the transport of liquid or gaseous, heated or cooled media, in which the conduit is foamed and provided with a protective plastic jacket.

Processes for the continuous as well as discontinuous production of thermally insulated conduits which are provided on the outside with a protective jacket made of plastic are known.

Various of the known continuous methods consist in that the conduit provided with spacers is guided through a stationary shaped tube together with a plastic film tube serving as a protective jacket, the joining and welding together of the edges of the plastic tape to the plastic film tube shortly before the insertion into the stationary molded tube. The plastic mixture to be foamed is generally applied to the plastic film strip shortly before the overlapping edges of the plastic film strip formed into the plastic film tube are joined and welded together. Then, during the passage through the stationary molded pipe, the annular space between the pipe and the tubular outer protective jacket is foamed. If necessary, instead of the plastic film tube, an aluminum film coated on both sides with copolymers can be used in this process and the protective jacket can be extruded after the foamed conduit has passed through the stationary molded pipe using an extruder (DE-OS 3 307 865).

However, these continuous processes have not been able to establish themselves in practice in the case of conduit pipes with a larger diameter, since the frictional forces between the outer jacket and the stationary molded pipe, due to the foam pressure, are too great to ensure rapid passage through the stationary molded pipe, even if you add an additional lubricant between the outer jacket and the stationary pipe.

Compared to this continuous process, a discontinuous process is therefore carried out in practice, in particular for line pipes with lengths of 6 to 12 m and diameters of 20 to 60 mm, in which the line pipe is initially provided with foam-permeable spacers and with a relatively thick one at certain intervals Plastic hose is covered. The structure prepared in this way is then gradually foamed in an inclined position. The thickness of the plastic tube in this process depends on the foam pressure that occurs, since it not only has the task of forming the outer jacket, but also serves as a “shape”. Therefore, the plastic hose must be designed so that it can absorb the foam pressure that occurs. A disadvantage of this method is therefore not only the necessary use of the thick plastic tube, but also the fact that no uniform foam is produced by the inclined foam and that the foam also has a relatively high density. In addition, the discontinuous procedure is not economical.

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The object of the present invention is therefore to provide a method and a device with which it is possible to produce line pipes, even those with a larger diameter, continuously and economically, while at the same time saving material for the outer jacket and forming a uniform foam Density in the thermally insulating layer.

This object is achieved according to the invention in that

(a) continuously introduces the conduit pipes to be foamed into a tubular cavity formed by a double-block block belt conveyor system with simultaneous foaming in the axial direction, whereby

(b) the foamable plastic mixture is set in such a way that it is hardened to the extent that it performs a function for the conduit if the conduit would kink or sag due to its own weight, and

(c) extruded a foamed plastic protective jacket with a high density by extrusion into the foamed conduit after leaving the double mold block chain belt system in an extruder by means of an annular die.

The double mold block chain belt system used according to the invention is known per se and is used, for example, for the continuous production of longitudinally slotted foam insulating pipes according to DE-AS 1 266 485 or for the continuous production of two collapsible, foamed tubular half-shells connected by an outer film according to DE-PS 2 503 425.

In the continuous production of the longitudinally slotted foam insulation tubes according to DE-AS 1 266 485, the holding of the core, which extends over the entire length of the molding channel formed by the two movable mold block chains, and which is necessary for forming the interior of the foam insulation tube, posed particular difficulties. It has been shown that even if the core is firmly clamped at both ends, the pressure generated by the foam in the molding channel is still so strong that the core cannot be centered over its entire length. In order to avoid such deviations, the core was therefore additionally provided over its entire length with a supporting holding plate which protrudes radially into the mold channel between the mold blocks arranged opposite one another.

The same with regard to the deflection of the core also applies to another known system, which has a fixed mandrel as the inner core, which is only attached to the inlet end of the system and projects freely into the fixed or circumferential outer shape. Here too, the mandrel, which is only clamped on one side, does not have sufficient stability to absorb the pressures occurring during foaming without deflection. In this context, reference is made to the statements in DE-PS 2 503 425, column 3, lines 49 ff cited above. Because of the problem of the aforementioned mandrel deflection, the proposal is made in another known system according to DE-AS 2 165 584 to control the deflection of the mandrel by means of a laser beam and to make an escape correction using regulating and control elements. Using this auxiliary device, however, it is difficult to achieve perfect alignment of the fixed inner core (mandrel), quite apart from the fact that the entire system is very, very complicated and very susceptible to failure.

On the basis of the experience gained with such double-form block chain belt systems in connection with the production of elongated slotted foam insulating pipes, it is to be regarded as extremely surprising that in the process according to the invention using a double-form block chain belt system with foam plastic, insulated conduit pipes are obtained, in which even the conduits with large diameters are fixed in position concentrically in the foam plastic without the use of spacers.

The continuous procedure that is possible through the use of the double mold block chain conveyor system allows continuous foaming of the conduits, which has the advantage that the foam covering has a homogeneous cell pattern over the entire length without bubbles with a low density, which means that not only one uniform mechanical strength, but also better lambda values are given.

By means of the extruder connected to the double mold block chain conveyor system and the associated vacuum calibration device, it is also possible to produce the foamed plastic protective sheath with high density and smooth outer skin in an economical manner. In addition, the plastic protective sheath can be designed to be considerably thinner in the method according to the invention than in the discontinuous method described at the outset, since the pressure which occurs when the thermally insulating foam layer is formed no longer needs to be absorbed by the plastic sheath. Thus, in the method according to the invention, the functions of the plastic jacket are reduced to diffusion tightness and protection against injury during transport and during laying. The foamed protective jacket reduces weight, price and increases flexibility. It preferably consists of a foamed polyethylene, polypropylene, polyvinyl chloride or the like and preferably has a density of 500 to 800 kg / m3.

Since the system according to the invention is designed in such a way that the line pipes are automatically concentric with the outer jacket, that is to say in the middle, it is also possible to dispense with all spacers or centering devices, as are necessary in the methods according to the prior art. This has the further advantage that the many cold bridges are eliminated, as a result of which the thermally insulated conduit produced according to the invention is further improved and made cheaper.

The inventive method is suitable for all thermally insulated conduits, such as. B. those made of copper, steel or plastic. In the case of copper or plastic pipes, these can be used for smaller diameters, e.g. B. with diameters of 22 mm, from the roll on which they are delivered in lengths of 50 meters or more, after appropriate linear alignment practically endlessly fed to the double mold block chain conveyor system and wound up again on a roll after foaming and application of the plastic jacket will.

In the case of plastic pipes with larger diameters, these are best produced by extrusion directly in front of the device used according to the invention, so that there is no need to handle the pipes. After leaving the device used according to the invention, the line pipes, which can no longer be wound up on a roll, are cut into the thermally insulated line pipes of the desired length.

Rigid pipes, e.g. B. steel pipes or other metallic pipes, are preferably used in pieces of 12 to 18 m, which shortly before insertion into the device used according to the invention connected with special plastic sleeves to form an “endless strand” and then practically also “endlessly” continuously foamed and coated . After the sheathing, the pipes are then cut with a special saw in the area of the sleeves, i.e. H. the pipe

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Connectors disconnected again. The pipe connectors are designed in such a way that after removal of the thermally insulated pipe pipes they release the pipe ends without foam insulation, so that the pipe pipes can then be connected tightly and permanently with conventional pipe connection pieces and then insulated.

Any suitable plastic provided with blowing agents or corresponding starting components forming the respective plastic can be used to produce the thermally insulating foam layer.

Depending on the 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 cases where the “endless” thermally insulated conduit pipes are wound on a roll after leaving the device used according to the invention. In contrast, it can be advantageous to produce a rigid foam with rigid pipes.

Suitable foams preferably include polyurethane foams, polyisocyanurate foams, polyolefin foams, in particular polyethylene or polypropylene foams or foams of corresponding copolymers thereof, and polystyrene foams.

When producing polyurethane foams, regardless of whether they are flexible or rigid, it is necessary to use a separating film, which is inserted together with the conduit into the double mold block chain conveyor system in such a way that it comes to rest on the mold blocks. The annular space between the separating film and the conduit is then foamed.

Any type of film can be used as a release film, for example paper, plastic or metal. To achieve a pure separating effect, it is sufficient to use paper or a plastic film as the separating film. However, if you have additional effects such. B. desires a heat reflection or a vapor barrier, it is advantageous to use a metal foil, for. B. use an aluminum foil coated with paper or plastic on one or both sides.

On the other hand, with certain types of foam, e.g. B. in those made of polyethylene or polystyrene, work without a release film, since it may be sufficient if the mold block chains are treated with a conventional mold release agent on return. If one works with mold block chains additionally cooled during the return, one can even achieve with a suitable procedure that a relatively firm, largely homogeneous surface skin is obtained, so that it may even be possible to do without the outer plastic protective jacket.

The foamable mixture is introduced into the annular space between the conduit and the separating film or mold block chains in the usual manner, for example as described in DE-OS 3 307 865, which was dealt with at the beginning, by placing the foamable mixture on the separating film before joining it to form the film tube applies. The setting of the foamable plastic, preferably components A and B to form polyurethane foams, takes place in such a way that the foam fills the annular space between the conduit pipe and the separating film shortly after the tubular shaped separating film provided with the foamable mixture has entered the double-mold block chain belt system and at the same time the conduit is held concentrically by the now stable foam. 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 signaling conductors can be foamed in at a distance from the pipe when the pipe is being foamed. These signaling conductors serve to report and localize moisture that has penetrated into the foam layer.

Of course, the method according to the invention also allows the simultaneous foaming in of a plurality of conduits which are insulated from one another and are then surrounded by a common plastic protective sheath. Advantageously, two conduits will be placed in a protective plastic jacket and insulated from one another, the cross section through such a composite structure being preferably not round, but oval. This arrangement is used, for example, as a branch line from the main line to the customers, so that the supply and return lines are accommodated in one unit, which can reduce the transport and installation costs.

The present invention is further explained below with reference to FIGS. 1 to 4, which represent particularly preferred embodiments, but without restricting it.

Fig. 1 shows a schematic representation of a top view of the core of the inventive device.

FIG. 2 shows a schematic representation of a cross section through the mold blocks (5a, 5b, 5a ', 5b') forming the double mold block chains of the belt system (5) along the section line AA in FIG. 1.

3 shows a cross section through a thermally insulated conduit 7 according to the invention.

4 shows in cross section a pipe connector 12.

1 to 4 and the following explanations, the reference symbols have the following meaning:

1 conduit

2 release film supply roll

3 release film

4 foaming machine

5 double form block chain belt system

5a, 5b, 5a ', 5b' form blocks forming the form block chain

6 vacuum calibrated extruders

7 thermally insulated conduit

8 the molding channel formed by the molding blocks 5a, 5b

9 Frame for guiding the mold block chains

10 thermally insulating foam layer

11 foamed plastic protective jacket

12 pipe connector

1, two mold halves are provided, which are divided lengthways into individual mold blocks 5a, 5b, 5a ', 5b' and which move along a straight line at a conforming speed. The individual mold blocks 5a, 5b form the necessary mold channel and are pressed outside of the manufacturing area as separate mold blocks 5a ', 5b' (see FIG. 2) on the guide frame 9 in a manner known per se and redirected. The mold blocks 5a, 5b can be exchanged for adaptation to the respectively desired diameter of the conduit or the thermally insulating foam sheath to be produced.

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 feed and holding device via a straightening tool of the double mold block chain belt system 5 together with that of the separating line. Supply roll 2 unwound release film 3 fed, where5

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the separating film 3 is provided with the foamable mixture by means of the foaming machine 4 and is formed into a tube before entering the double mold block chain belt system 5. After leaving the double mold block chain conveyor system 5, the conduit 1 provided with the foam layer 10 is passed through the extruder 6 provided with a vacuum calibration device, where the actual foamed plastic protective jacket is on the separating film 3

11 is applied with a high density. The thermally insulated conduit 7 thus finished (see FIG. 3)

is then wound up on a transport roll and brought to the place of use, where it is laid from the roll.

According to another preferred embodiment according to the present invention, rigid, non-flexible line pipes 1, in particular those with larger diameters in lengths of 6 to 18 m, preferably of.

12 to 18 m, from a storage rack, not shown in FIG. 1, by means of the pipe feed and holding device, also not shown, of the double-block block belt conveyor system 5, together with the separating film 3 and the foamable mixture, in the manner described above . In order to ensure a continuous mode of operation, the conduit pipes 1 to be insulated are connected one after the other by means of the pipe connecting pieces 12 shown in FIG. 4 and guided through the double-form block chain belt system 5 as an almost endless strand. The tube connecting pieces 12 are in their outer and inner diameter the respective conduit 1 and the desired thermally insulating foam 671 543

layer 10 adjusted. After leaving the extruder 6 provided with a vacuum calibration device and applying the protective plastic jacket 11, the pipe connection piece 12, which is not visible from the outside, is sawed through in the center transverse to the longitudinal axis by means of a controlled saw. The thermally insulated conduits 7 separated again in this way are placed on a storage rack of the packaging or. Bundling unit fed. The cut pipe connectors advantageously remain connected to the thermally insulated pipe pipes 7 until they are installed and are only removed from the pipe pipes shortly before assembly.

Of course, you can also separate the thermally insulated pipe 7 emerging from the vacuum calibration device of the extruder 6 from the pipe connection pieces 12, so that these non-sawn pipe connection pieces 12 can be used again and again after removing the separating film 3 with protective plastic jacket 11. The thermally insulated conduits 7 freed from the pipe connectors 12 can then be provided with other protective caps for transport until assembly, if this is desired.

Another advantage that results from the use of the pipe connection piece 12 is the fact that after removal of the pipe connection piece 12 the line pipe ends are immediately free for the later required, usual permanent and tight pipe socket connection.

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1 sheet of drawings

Claims (10)

671543 PATENT CLAIMS 1. A process for the continuous production of thermally insulated conduits with a protective plastic jacket for the transport of liquid or gaseous, heated or cooled media, in which the conduit is foamed and provided with a protective plastic jacket, characterized in that (a) continuously introduces the conduit pipes (1) to be foamed into a tubular cavity (8) formed by a double mold block chain belt system (5) with simultaneous foaming in the axial direction, whereby (b) the foamable plastic mixture is set in such a way that it is hardened at the latest and performs a function for the conduit (1) if the conduit (1) would kink or sag due to its own weight, and (c) a foamed plastic protective jacket (11) with a high density is extruded onto the foamed conduit (1) after leaving the double mold block chain belt system (5) with an extruder (6) by means of an annular nozzle. 2. The method according to claim 1, wherein the conduit is foamed using a film (3) acting as a release agent compared to the device, characterized in that the extruder (6) is cooled and vacuum calibrated. 3. The method according to claim 1 or 2, characterized in that prior to the foaming of the gap between the conduit (1) and the mold blocks (5a, 5b) of the double block block belt conveyor system (5) one upon entry into the double block block chain Introduces the belt system (5) into a tube-shaped separating film (3), preferably one made of paper, from aluminum film coated with plastic or paper, or from plastic and only then foams the annular space between the conduit (1) and separating film (3). 4. The method according to claim 3, characterized in that the space between the conduit (1) and separating film (3) is foamed with a starting mixture forming a polyurethane foam. 5. The method according to claim 3, characterized in that a polyolefin provided with blowing agent, preferably polyethylene or PVC, is used to produce the foamed plastic protective jacket (11). 6. Apparatus for carrying out the method according to claim 1 to 5, characterized by a double mold block chain belt system (5) provided with a foaming machine (4), a pipe feed and holding arrangement before its entry and an extruder (6) after its exit. is arranged with an annular nozzle for producing the foamed plastic protective jacket (11). 7. The device according to claim 6, characterized in that the pipe feed and holding device comprises a pipe straightening tool. 8. The device according to claim 6 or 7, characterized in that the extruder (6) is cooled and vacuum calibrated. 9. Device according to one of claims 6 to 8, characterized in that the foaming machine (4) is a 2-component mixing machine for the production of polyurethane foams. 10. A thermally insulated conduit (7), produced by the method according to one of claims 1 to 5, characterized in that the plastic protective sheath (11) located on the thermally insulating foam layer (10) consists of a plastic foam with a high There is a density and a smooth closed-cell surface.