LU86559A1 - METHOD AND DEVICE FOR PRODUCING THERMALLY INSULATED PIPES - Google Patents

Description

METHOD AND DEVICE FOR PRODUCING THERMALLY INSULATED PIPES

The present invention relates to a method and an apparatus for the continuous production of thermally insulated conduit pipes with a plastic protective jacket for the transport of liquid or gaseous, heated or cooled media, in which the conduit pipe is foamed and with, optionally using a film which acts as a release agent with respect to the device is provided with a protective plastic jacket.

Methods 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 processes consist in that the conduit provided with spacers is passed through a stationary molded tube together with a plastic film tube serving as a protective jacket, the joining and welding together of the edges of the plastic band to the plastic film tube shortly before insertion into the stationary molded pipe takes place.

The plastic mixture to be foamed is usually applied to the plastic film tape shortly before the joining and welding of the overlapping edges of the plastic film tape formed into the plastic film tube. The annular space between the conduit and the tubular outer protective jacket is then foamed during the passage through the stationary molded pipe. If necessary, an aluminum foil coated on both sides with copolymers can be used in this process instead of the plastic film tube and the protective sheath can be extruded after the foamed conduit has passed through the stationary molded pipe using an extruder (DE-OS 33 07 865).

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 a 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 from 6 to 12 m and diameters from 20 to 60 mm, in which the line pipe is initially provided with foam-permeable spacers and at a relatively thick thickness Plastic hose is covered. The structure prepared in this way is then gradually foamed in an inclined position. The thickness of the plastic hose 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 strong that it can absorb the foam pressure that occurs. A disadvantage of this method is not only the necessary use of the thick plastic hose, but also the fact that no uniform foam is created by the inclined foam and the foam also has a relatively high density. In addition, the discontinuous process I.

- 3 - / wise is not economical.

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

This object is achieved according to the invention in that (a) the conduit pipes to be foamed are continuously introduced centrally into a tubular cavity formed by a double mold block chain belt system with simultaneous foaming in the axial direction, 1 wherein (b) the foamable plastic mixture is adjusted in this way is that it is hardened at the latest and has a supporting function for the conduit if the conduit would kink or sag due to its own weight, and (c) on the foamed conduit after leaving the

Double-form block chain belt system in a possibly cooled and evacuated calibration device by means of an annular nozzle extruded a foamed plastic protective jacket with a high density.

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 insulation pipes according to DE-AS 12 66 485 or for --4-! i i Continuous production of two collapsible, foamed tubular half-shells connected in a hinge-like manner by means of an outer film in accordance with DE-PS 25 03 425.

Particular difficulties in the continuous production of the longitudinally slotted foam insulating pipes according to DE-AS 12 66 485 were 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 insulating pipe. 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 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 25 03 425 cited above, column 3, lines 49 ff. Because of the problem of the aforementioned mandrel deflection, the proposal is made in another known system according to DE-AS 21 65 584 to control the deflection of the mandrel by means of a laser beam and to make an escape correction using regulating and control elements. By means of this auxiliary device, 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 tape systems in connection with the production of longitudinally 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 tape system with foam plastic insulated conduit pipes is obtained which even the pipes with large diameters are concentrically fixed in the foam plastic without the use of spacers.

The continuous procedure possible through the use of the double mold block chain belt system allows continuous foaming of the line pipes, 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 belt system with 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 process according to the invention than in the discontinuous process described at the outset, since the thermal insulation foam /

Layer occurring pressure no longer needs to be intercepted by the plastic jacket. 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 when 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 / m 2.

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, in the center — it can also be used for all Centering holder, as they are necessary in the methods according to the prior art, are dispensed with. This has the further advantage that the many cold bridges are eliminated, whereby the thermally insulated conduit produced according to the invention is further improved and cheaper.

The method according to the invention is suitable for all thermally insulated line pipes, e.g. those made of copper, steel or plastic. In the case of copper or plastic pipes, these can be used with smaller diameters, e.g. with diameters of 22 mm, from the roll on which they are delivered in lengths of 50 meters or more, after a corresponding straight alignment, they are fed practically endlessly to the double mold block chain conveyor system and, after being foamed and applied, are rewound on a roll .

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 handling with the

No pipes are required. 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. Steel pipes or other metallic pipes are preferably used in pieces of 12 to 18 m, which shortly before being inserted into the device used according to the invention are connected with special plastic sleeves to form an "endless strand" and then practically also "continuously" foamed and encased continuously. After the sheathing, the pipes are then cut with a special saw in the area of the sleeves, i.e. the pipe connectors are separated again. The pipe connectors are designed so that after removal of them when laying the thermally insulated pipes, they release the pipe ends without foam insulation, so that the pipes can then be tightly and permanently connected with conventional pipe connectors 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 of advantage with rigid pipes to produce a rigid foam.

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 against 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 separation effect, it is sufficient

Use paper or a plastic film as a release film. However, if you have additional effects such as heat reflection or vapor barrier, it is advantageous to use a metal foil, e.g. 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. for 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 when they return. If you work with mold block chains that are additionally cooled during the return, you can even achieve with a suitable procedure that a relatively firm, largely homogeneous surface skin is obtained, so that it is even possible to dispense with 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 33 07 865, 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 foam, which is now 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 signaling conductors can be foamed in at a distance from the pipe when the pipe is being foamed. These signaling conductors are used to report and locate moisture that has penetrated the foam layer.

Of course, the method according to the invention also allows the simultaneous foaming in of a plurality of conduit pipes 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 an i i -. 10 -

Composite structures are 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 device according to the invention.

2 shows a schematic representation of a cross section through the form blocks (5a, 5b, 5a1 2 3 4 5, 5b ') forming the double form block chains of the belt system (5) along the section line A-A in FIG. 1.

i

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

v Fig. 4 shows in cross section a pipe connector 12.

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

Line pipe 2

Release film supply roll 3

Release film 4

Foaming machine 5

Double mold block chain belt system / - 11 - 5a, 5b, 5a1, 5b1 the mold blocks forming the mold block chain 6 vacuum-calibrated extruder 7 thermally insulated conduit 8 the mold channel 9 formed by the mold blocks 5a, 5b frame for guiding the mold block chains 10 thermally insulating foam layer 11 foamed Plastic protective jacket 12 pipe connector

In the case of 1 schematically illustrated double-mold block chain belt system 5, 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 tightly pressed against one another and are diverted and returned outside the production area as separate mold blocks 5a1, 5b '(see FIG. 2) on the guide frame 9 in a manner known per se. 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 fed from a supply roll by means of a pipe feed and holding device via a straightening tool of the double mold block chain belt system 5 together with that of the separating film supply roll 2 unwound release sheet 3, the release sheet 3 before entering the double mold block - - 12 - /

J

chain conveyor system 5 is provided with the foamable mixture by means of the foaming machine 4 and is formed into a tube. After leaving the double mold block chain belt system 5, the conduit 1 provided with the foam layer 10 is guided through the extruder 6 provided with a vacuum calibration device, where the actual foamed plastic protective jacket 11 with a high density is applied to the separating film 3. 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 conduits 1, in particular those with larger diameters in lengths from 6 to 18 m, preferably from 12 to 18 m, from a storage rack, not shown in Fig. 1 by means of the in the Also not shown, pipe feed and mounting device 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 operation, the line pipes 1 to be insulated are successively by means of the from 4 visible pipe connectors 12 connected and guided as a quasi endless strand through the double-block block belt system 5.

The tube connecting pieces 12 are adapted in their outer and inner diameter to the respective conduit 1 and the desired thermally insulating foam layer 10. 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. That way /! ί, '\ - 13 - again separated thermally insulated conduits 7 are fed to the packaging or bundling unit via a storage rack. The cut pipe connectors advantageously remain connected to the thermally insulated conduit 7 until they are installed and are only removed from the conduit 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 connectors 12 so that these non-sawn pipe connectors 12 can be used again and again after removing the separating film 3 with a plastic protective 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 connector 12 used according to the invention can be seen in the fact that, after the pipe connector 12 has been removed, the line pipe ends are immediately free for the later required, customary permanent and tight pipe socket connection.

Claims (7)

1. A process for the continuous production of thermally insulated conduits with a plastic protective sheath for the transport of liquid or gaseous, heated or cooled media, in which | the conduit, optionally using one of the device as a release agent; kenden film, foamed and provided with a protective plastic sheath, characterized in that i (a) the conduits (1) to be foamed continuously | lent into a tubular cavity (8) ί formed by a double-form block chain belt system (5). with simultaneous foaming in the axial direction, whereby I (b) the foamable plastic mixture is set so that it is hardened at the latest and has a function for the conduit (1)! exercises if the conduit (1) would kink or sag due to its own weight, and (c) by means of an optionally cooled, vacuum-calibrated 'extruder (6) after exiting the foamed conduit (1) after leaving the double mold block chain conveyor system (5) an annular nozzle extruded a foamed plastic protective sheath (11) with a high density. ! / / - 15 - c- 2. The method according to claim 1, characterized in that prior to the foaming of the space between the conduit (1) and the mold blocks (5a, 5b) of the double block block belt system (5) one upon entry into the double block chain belt system ( 5) introduces a separating film (3) formed into a tube, preferably one made from paper, from aluminum foil coated with plastic or paper, or from plastic and only then the annular space between the conduit (1) and separating | Foam (3) foams. 3. The method according to claim 1 and 2, characterized in that the space between the conduit (1) and release film (3) is foamed with a starting mixture forming a polyurethane foam 'substance. ] 4. The method according to claim 1 and 2, characterized in! that one uses a blowing agent-provided polyolefin, preferably polyethylene or PVC, to produce the foamed plastic protective jacket (11). 5. Apparatus for carrying out the method according to claim 1 to 4, characterized by a known, with a foaming machine (4) provided double mold block chain belt system (5), before entering a pipe feed and holding device, optionally with a pipe straightening tool , and after their exit an optionally cooled, vacuum-calibrated extruder (6) with an annular nozzle for producing the foamed plastic protective jacket (11) is arranged. 6. The device according to claim 5, characterized in that the foaming machine (4) is a 2-component mixing - 16 - machine for the production of polyurethane foams. 7. A thermally insulated conduit (7), characterized in that the plastic protective sheath (11) located on the thermally insulating foam layer (10) consists of a plastic foam with a high density and a smooth closed-cell surface. i j