FI91374B - Process for continuous production of a heat insulated pipe with a plastic protective jacket - Google Patents

Description

91374

Method for continuous fabrication of a thermally insulated pipe with a plastic sheath.

The present invention relates to a method for the continuous production of a thermally insulated pipeline with a plastic protective jacket for conveying liquids, wherein the circumferentially foamable pipeline is continuously fed into a tubular cavity in the double mold chain belt device. avaipalla.

Methods for the continuous as well as intermittent fabrication of thermally insulated pipelines with an external plastic sheath are known.

Various known continuous manufacturing methods comprise passing a spacer pipeline together with a plastic sheath hose acting as a shield through a fixed mold tube, whereby the joints of the plastic strip and welding to the plastic hose take place shortly before the fixed mold tube is inserted. The foamable plastic mixture is generally applied shortly before joining and welding the overlapping edges of the plastic film strip formed in the plastic hose to the plastic film tape. During the transit time of the fixed mold tube, the annular space between the pipeline and the tubular outer sheath is then filled with foam. In connection with this method, it is possible to use an aluminum film coated on both sides with copolymers instead of a plastic film hose, in which case the protective jacket is extruded by means of an extruder after the foamed pipe 30 has passed through a fixed mold tube (DE-OS 33 07 865).

However, this continuous method has not been able to be used with larger diameter pipelines because the frictional forces between the outer jacket 35 and the fixed mold tube become too large for rapid pipeline passage through the fixed mold tube, even if the outer casing and fixed mold tube are inserted.

Instead of these continuous methods, in particular for pipelines with a length of 6-12 m and a diameter of 20-60 mm 5, a discontinuous method has been used, in which the pipeline is first provided with foam-permeable spacers at certain distances and covered with a relatively thick plastic hose. The conductor structure thus formed is then gradually foamed in an inclined position. The thickness of the plastic hose is determined by the foam pressure present in this method, since its purpose is not only to form the outer jacket, but also to act as a "mold". In addition, the plastic hose must be strong enough to withstand the foam pressure that exists. The disadvantage of this method 15 is thus not only the necessity of using a thick plastic hose, but also the fact that the foaming in the inclined position does not produce a uniform foam and, in addition, the relatively high specific gravity of the resulting foam. Such a discontinuous method is also not economically advantageous.

It is therefore an object of the present invention to provide a method by which it is also possible to produce larger diameter pipelines in a continuous and economically advantageous manner while saving the material of the outer sheath 25 and forming a uniform thickness of heat-insulating foam layer of smaller thickness.

This object according to the invention is achieved by using rigid, non-flexible pipelines with a larger diameter, preferably 20-60 mm and a length of 6-18 m, which are connected to each other by pipe fittings and which are routed as a seemingly endless conduit. through which the pipe fittings are cylinders which have veu * Btet * u axial gripping bores at their opposite ends.

3 91374 wherein the diameter of the gripping boreholes corresponds to the outer diameter of the tubes and the outer diameter of the cylinders to the inner diameter of the mold channel of the double-molded chain belt device, and 5 b) the foamable plastic composition is made 10 c) after leaving the dual-molded pipeline belt device in the round-foamed pipeline, the ring is extruded with a possibly cooled vacuum-calibrated extruder through a nozzle with a foamed, high-specific-weight plastic sheath.

15

The double mold chain belt device used according to the invention is known per se and is described, for example, as a device for the continuous production of longitudinally cut foam insulation pipes according to DE-AS 12 66 485 or by means of two outer outer film as a device for manufacturing.

Particular difficulties were caused in the continuous production of longitudinally slit foam plastic insulation pipes according to DE-AS 12 66 25 485 by holding a casting core extending over the entire length of the mold channel formed by both movable mold block chains and required to form the interior of the foam insulation pipe. Namely, it has been found that although the core is firmly attached at both ends, the pressure exerted by the foam on the mold channel is so strong that the core cannot be held centrally in its entire length. To avoid such positional deviations, the core was additionally provided along its entire length with a load-bearing fastening plate extending radially in the mold channel 5 between opposite mold blocks.

The same disadvantage with respect to the positional deviation of the casting core also occurs in another known device, in which a fixed spindle pin is used as the inner core, which is attached only to the feed end of the device and extends freely into a fixed or rotating outer mold. Also in this case, not only the one-sidedly mounted spindle pin is able to provide sufficient stability to receive the pressure associated with the foam without a positional deviation. In this connection, reference is made to the structures according to column 3, lines 49 of the aforementioned publication DE-PS 25 03 425. Due to said problem with the deviation of the spindle pin, it has thus been proposed in connection with another known device according to DE-AS 21 65 584 to monitor the deviation of the spindle pin by means of a laser beam and to carry out the correction by means of adjustment and control elements.

However, with this auxiliary device, it is difficult to perform a trouble-free repair of the fixed inner core (spindle) simply because the device in question is very complex and prone to interference.

In accordance with the experience gained in the use of said double molded chain belt devices in the manufacture of longitudinally cut foam insulation pipes, it has been surprisingly found that in connection with the method according to the invention

35 5 91374

The continuous method made possible by the use of a double mold chain belt device allows continuous flotation of the pipelines, which has the advantage that the foam filling comprises a cell structure of the same length without smaller specific gravity bubbles, thus achieving better mechanical insulation in addition to equal mechanical strength.

In addition, by means of the extruder connected downstream of the double mold chain belt device and the associated calibration device 10, it is possible to economically achieve a foam jacket of a high specific gravity and a smooth outer surface. In connection with the method according to the invention, the foam-plastic jacket can also be made considerably thinner than in the intermittent process described above, since the pressure present during the formation of the heat-insulating foam plastic layer no longer has to be taken into account in the foam jacket. Thus, in the case of the method according to the invention, the effect of the foam jacket is reduced with respect to the diffusion-tightness and the protection provided to prevent damage during transport and installation. Foamed protective cover reduces weight and cost and increases flexibility. This diaper mainly comprises foamed polyethylene, polypropylene, polyvinyl chloride or the like, the specific gravity 3 being preferably 500-800 kg / m 3.

Since the device used in the method according to the invention is set up so that the pipelines are automatically positioned concentrically - i.e. centrally - with respect to the outer jacket, the use of any spacers or centering supports which are necessary in connection with the methods currently in use can be avoided. In this case, the additional advantage is also obtained that several "cold bridges" are eliminated, whereby the thermally insulating pipeline prepared in accordance with the invention becomes further substantially better and cheaper.

The method according to the invention is suitable for use in connection with all thermally insulating pipelines, such as kuDari, steel or plastic pipes. Copper and plastic tubes can be supplied in coils of smaller diameters, for example 22 mm in diameter, wound on rolls 50 m long or longer, fed to the double mold chain belt device practically endlessly after the corresponding rectilinear positioning, and wound on the roll again after rolling.

In the case of larger diameter plastic pipes, this is best achieved by means of extrusion immediately before the use of the device according to the invention, whereby the processing step of the pipes is omitted. After leaving the device according to the invention, the pipelines, which are no longer wound on a roll, are cut into thermally insulating pipelines of the desired length.

Rigid pipes, for example steel pipes or other metal pipes, are used in pieces 12-18 m long, which are connected to the device according to the invention shortly before feeding by special plastic sleeves into an "endless cable" and foamed and sheathed virtually "endlessly". After the jacket coating, the pipes are then again separated from each other by means of a special saw in the area of the sleeves, i.e. the pipe fittings. The pipe fittings are arranged in such a way that, after they have been removed, the ends of the pipes are left without foam-plastic insulation during the installation of the heat-shrinkable pipes, so that the pipes can be connected tightly and permanently in isolation via conventional pipe fittings.

35 7 91374 For the thermally insulating foam layer, any suitable plastic material provided with a blowing agent or corresponding starting components forming each plastic material can be used.

5 Depending on its intended use, the plastic material of the heat-insulating layer may be more flexible or stiffer. The use of flexible foams is recommended, for example, when "endless" thermally insulated pipelines are wound on a roll after leaving a device 10 according to the invention. In contrast, in the case of rigid pipes, it may be advantageous to use hard foam.

Suitable foam materials are mainly polyurethane, polyisocyanurethane, polyolefin and in particular polyethylene or polypropylene foams or foams of their corresponding copolymers, as well as poly-styrene foam foams.

Polyurethane foams, both more flexible and stiffer grades, require a separating film which, together with the conduit, is fed to the double mold chain belt device so that it comes next to the mold blocks. The reno-like space between the separation membrane and the pipeline is then foamed.

As the separating film, any film sheet 25 can be used, such as a paper, plastic or metal film. To achieve the separating effect, it is sufficient to use a paper or plastic film as the separating film. If, on the other hand, additional effects, such as thermal reflection or vapor barrier, are desired, it is preferable to use a metal film, for example an aluminum film coated on one or both sides with paper or plastic.

On the other hand, for certain types of foam, such as polyethylene or polystyrene, it is possible not to use a separating film, since it may be sufficient for the mold block chains to be treated with a conventional mold release agent during the return movement. If these mold-block chains are additionally cooled during the return movement, a relatively solid and almost homogeneous surface cover can be obtained in connection with a suitable method, whereby even the outer plastic protective sheath can possibly be dispensed with.

The supply of the foamable mixture to the annular space 10 between the guide tube and the separating film or the mold block chains takes place in a conventional manner, as described, for example, in the above-mentioned DE-OS 33 07 865, whereby the foamable mixture is applied to the separating film before being connected to the film. The foamable plastic, mainly the components for forming the polyurethane foam, is placed in such a way that after feeding the tubular separating film already provided with a slightly foamable mixture to the double mold chain belt device, the annular space between the guide tube and the separating film is kept in the foam with the help of foam. The measures required for this are familiar to a person skilled in the art or can be carried out without difficulty.

If desired, when foaming the conduit 25, one or more detector leads may also be placed inside the foam at a certain distance from the conduit. These detector wires indicate and locate the moisture that has penetrated the foam layer.

Of course, the method according to the invention also allows the foaming of a plurality of insulated conduits 30 which are then surrounded by a common plastic sheath. In this case, it is advisable to place the two conductor tubes in one plastic sheath and to insulate these conductors relative to each other, so that the cross-section of such a connecting structure is not substantially circular but oval. This arrangement can be used, for example, as a branch line from the main line to the consumers, in which case the supply and return water line is placed in one structural unit, which makes it possible to reduce transmission and installation costs.

Particularly preferred non-limiting embodiments of the present invention will now be described with reference to Figures 1-4.

Figure 1 schematically shows a plan view of a core part of a device according to the invention.

Fig. 2 schematically shows a cross-section of the mold blocks (5a, 5b, 5a 'and 5b') forming the double mold chains of the belt device (5) taken along the line 15A-A in Fig. 1.

Figure 3 shows a cross-section of a thermally insulated conduit 7 according to the invention.

Figure 4 shows a cross-section of a pipe connection piece 12.

In Figures 1-4 and later, reference numerals have the following meanings: 1 guide tube 2 separating film storage roll 3 separating film 25 4 flotation machine 5 mold channel 9 rack for guiding mold block chains 10 thermally insulating foam layer 35 10 11 foamed plastic protective sheath 12 pipe connection piece

The double mold-chain belt device 5 schematically shown in Fig. 1 comprises two mold halves 5 divided longitudinally into individual mold blocks 5af 5b, 5a 'and 5b'f as these mold halves move in a straight line at equal speed. The individual mold blocks 5a, 5b form the required mold channel in a tightly compressed manner and are turned and guided outside the material as separate mold blocks 5a ', 5b # (see Fig. 2) to the guide bracket 9 in a manner known per se. The mold blocks 5a, 5b can be changed to accommodate the respective diameter of the conduit or the resulting thermally insulating foam jacket.

According to a preferred embodiment of the present invention, for example, a flexible copper or plastic tube is fed from a storage roll via a guide and retaining device to a diverting device formed into a hose. After leaving the double mold chain-25 belt device 5, a conduit 1 provided with a foam layer 10 is passed to an extruder 6 containing a vacuum calibrator, where an actual high specific weight foamed foam to the place of use where it is wound from the reel for use.

According to another preferred embodiment of the present invention, rigid, non-rigid, 35 91374 11 m in diameter and 6 to 18 m, most preferably 12 to 18 m in diameter conduits are fed from an invisible storage rack in Fig. 1 to an invisible double mold chain belt feeder 5. 5 together with the separating film 3 and the mixture to be foamed as described above. In order to ensure continuous operation, the insulated conduits 1 are connected in series by means of the pipe fittings 12 shown in Fig. 4 and are passed as a seemingly endless pipe 10 through a double mold chain belt device 5. The outer and inner diameters of the pipe fittings are adapted to each conduit 1 and the desired heat-insulating foam layer 10. After leaving the extruder 15 6 equipped with the vacuum calibrator and attaching the plastic sheath 11, the invisible pipe fittings 12 are sawn with a guided saw transversely transversely to the longitudinal axis. The thermally insulated conduits thus re-separated are led through a support rack to a packaging or bundling unit. The cut-out pipe fittings are preferably connected to the thermally insulated conduits until installation and are only removed shortly before the installation of the conduits.

Of course, the pipe fittings 12 can also be taken directly out of the heat-insulating conduits 7 leaving the vacuum calibrator of the extruder 6, whereby these intact pipe fittings 12 can be reused after removing the separating film 3 with a plastic sheath 11 on them. Thermally insulating conduits 7 without pipe fittings 12 can then be provided with other types of protective sheaths for transport until installation, if desired.

Another advantage provided by the pipe fitting 12 used in accordance with the invention is that, after the pipe fitting 12 has been removed, the ends of the pipeline immediately become free for the usual durable and tight pipe socket connection 5 required later.

10

Claims (2)

91374 1. A method for the continuous fabrication of a thermally insulated pipeline with a plastic sheath for transferring liquid or gaseous, heated or refrigerated media, wherein the circumferentially foamable pipeline is continuously fed and provided with a plastic sheath, characterized in that a) rigid, non-flexible pipes with a larger diameter, preferably 20-60 mm and a length of 6-18 m and 13 connected to each other by pipe fittings (12) are used as thermally insulated pipes (1) and which are passed as a seemingly endless line through a double mold chain belt device (3), the pipe fittings being cylinders with axial 20 t at their opposite ends the boreholes, wherein the diameter of the gripping bore holes corresponds to the outer diameter of the tubes and the outer diameter of the cylinders to the inner diameter of the mold channel of the double mold chain belt device, and b) the foamable plastic mixture is made such that it ) due to its own weight, and c) the double molds are extruded into the circumferentially foamed pipeline (1) after leaving the guide belt device (5) with 30 possibly cooled vacuum calibrated extruders (6) via a ring nozzle foamed with a high specific gravity sheath. Method according to Claim 1, characterized in that a separating film (3) formed as a hose is inserted between the mold blocks (5a, 5b) of the pipe sleeve (1) and the double mold chain belt device (5) before flowing this space into the double mold chain belt device 5. ), which is preferably made of paper, plastic or paper - coated aluminum foil or plastic, and that the annular space between the pipeline (1) and the separating foil (3) is only then foamed. Method according to Claims 1 and 2, characterized in that the space between the pipeline (1) and the separation membrane (3) is foamed with a starting mixture forming a polyurethane foam. Method according to Claims 1 and 2, characterized in that a polyolefin with a blowing agent, in particular polyethylene or PVC, is used for the production of the foamed plastic protective sheath (11). 91374 1. For use as a container for the transport of plastics in the form of plastics, for the transport of air or gas, with the use of a container, the colors of the container 5 of which may be used, in the case of a double form block, the image is stored under the same velocity in the center of the axle as in the axle box, stela, icke böjliga rör med större diameter, företrädesvis med en diameter av 20-60 mm och en längd av 6-18 m, och vilka rör är 15 förbundna med varandra medörst rörförbindningsstycken (12) och skenbart ändlös sträng föres genom bandan ) with a double-ended form, the colors of which are blocked (12) Darna, varvid gripurtagens diameter motsvarar 20 rörens ytterdiameter och cylindrarnas ytterdiameter mot weights inner diameter diameters having a bandwidth of the test with a double form block, and this is the case with the use of a barrier function (1) and (c) with the use of a barrier (1), with the form of a double block (5) with a double form block, with the eventual side, vacuum calibrated extruders ) and an annular extruder with a plunger (11) with high density. 35 2. For the purposes of Article 1, see Annex 1