DE3530187A1 - Process and device for producing thermally insulated conveying pipes - Google Patents

Abstract

The present invention relates to a process for continuously producing thermally insulated conveying pipes, in which the conveying pipe is provided allround with foam, using a film acting as a separating agent towards the device, and with a protective plastic sheath. The foaming round the conveying pipes takes place in a tubular cavity formed by a continuous unit with twin mould-block chains. The conveying pipe with foam round it is then provided in a vacuum-calibrated extruder by means of an annular die with a foamed protective plastic sheath of high density.

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, optionally using one opposite the device acting as a release agent, foamed and is provided with a protective plastic jacket.

Process for both continuous and discontinuous Manufacture of thermally insulated pipes, the outside with a protective jacket made of plastic are known.

Several of the known continuous processes exist in that the one provided with spacers Line pipe together with one that serves as a protective jacket Plastic film tube through a stationary molded tube leads, the joining and welding together of the Edges of the plastic tape to the plastic film tube shortly before insertion into the stationary molded tube. The plastic mixture to be foamed is usually just before joining and welding the itself overlapping edges of the to the plastic film tube molded plastic film tape on the plastic film tape applied. During the passage through the stationary The pipe is then foamed out of the annular space between the conduit and the tubular outer protective jacket. If necessary, instead of plastic  Foil tube one on both sides with copolymers coated aluminum foil and the protective jacket after passage of the foamed pipe through the stationary molded pipe extruded using an extruder be (DE-OS 33 07 865).

However, these continuous processes have been found Pipes with a larger diameter in practice cannot enforce, because the frictional forces between Outer jacket and stationary molded pipe, due to the occurring Foam pressure, too big to be a quick one To ensure passage through the stationary molded tube even if you are between the outer jacket and stationary molded tube introduces an additional lubricant.

In contrast to this continuous process, in in practice, especially for conduits with lengths of 6 to 12 m and diameters from 20 to 60 mm, a discontinuous Procedure carried out in which the conduit first at certain intervals with foam permeable Spacers and with a relatively thick plastic tube is covered. The structure so prepared is then gradually foamed in an inclined position. The The thickness of the plastic tube depends on this method after the foam pressure that occurs since it is not only the job is to form the outer jacket, but at the same time to serve as a "form". Therefore, the plastic hose be designed so strongly that he the occurring Catch foam pressure. A disadvantage of this method is not just the necessary use of the thick Plastic hose, but also the fact that no uniform foam is created by the inclined foaming and also the foam has a relatively high density having. Add to that the discontinuous procedure  is not economical.

The object of the present invention is therefore a method and to provide a device with which it is possible to use conduit pipes, even those with larger ones Diameter to produce continuously in an economical manner while saving material for the outer jacket and formation of an even foam low density in the thermally insulating Layer.

This object is achieved according to the invention in that
(a) continuously introduces the conduit pipes to be foam-coated into a tubular cavity formed by a double mold block chain belt system while simultaneously 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 that supports 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 in an optionally cooled and evacuated calibration device on the foamed conduit after leaving the double mold block chain conveyor system.

The double mold block chain used in accordance with the invention Belt system is known per se and is used, for example, for continuous production of longitudinally slotted foam insulation tubes according to DE-AS 12 66 485 or  continuous production of two over one outer film Hinged, collapsible, foamed Pipe half shells according to DE-PS 25 03 425.

The continuous was particularly difficult Manufacture of longitudinally slotted foam insulation pipes according to DE-AS 12 66 485 the holder of the core, which is over the entire length of the movable by the two Form block chains formed channel and extends to Formation of the interior of the foam insulating tube necessary is. It has been shown that even if the core is firmly clamped at both ends, anyway the pressure generated by the foam in the mold channel is so strong is that the core is not centered along its entire length can be held. To avoid such deviations, the core was therefore additionally along its entire length provided with a load-bearing mounting plate that radially in the form channel between the opposing ones Form blocks protrude.

The same applies to the deflection of the core with respect to another known plant that has a fixed one Has mandrel as the inner core that only at the inlet end the system is fixed and free in the fixed or circumferential outer shape protrudes. Owns here too the mandrel only clamped on one side is not sufficient Stability to the pressures occurring during foaming without To record deflection. It's going on in this regard the statements in the above-cited DE-PS 25 03 425, Column 3, lines 49 ff. Because of the problem of the aforementioned mandrel deflection is therefore used in another known system according to DE-AS 21 65 584 the proposal made by means of a laser beam the deflection of the Control Dorns and regulating and control elements make an escape correction. By means of this auxiliary device  but it is difficult to get a perfect alignment of the fixed inner core (thorn), quite apart from the fact that the whole facility was very, very complicated and is very prone to failure.

Due to the use of such double form block chain conveyor systems in connection with the manufacture of slotted slots Foam insulation tube experience gained, it is to be regarded as extremely surprising that one with the invention Method using a double Form block chain belt system insulated with foam plastic Receives line pipes, where even the line pipes with large diameters concentric in the foam plastic fixed in position even without using spacers are.

The through the use of the double form block chain belt system possible continuous procedure allowed a continuous foaming of the line pipes, the has the advantage that the foam wrapping A homogeneous cell pattern without bubbles over the entire length with low density, which means 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 jacket with high density and a 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 occurring during the formation of the thermally insulating foam layer no longer has to be absorbed by the plastic sheath. Thus, in the method according to the invention, the functions of the plastic material are reduced to diffusion tightness and protection against injury during transport and when laying. The foamed protective sheath 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 ³ .

Since the system according to the invention is designed so that the Line pipes automatically concentric to the outer jacket - in the middle - can also be used on all or centering holder, as used in the methods according to State of the art are necessary to be dispensed with. This has the further advantage that the many Cold bridges are eliminated, as a result of which the one produced according to the invention thermally insulated conduit continues is significantly improved and cheaper.

The method according to the invention is suitable for everyone thermally insulated conduits, such as. B. such made of copper, steel or plastic. In the case of copper or plastic pipes with 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 be, after appropriate straight line alignment the double form block chain conveyor system is practically endless fed and after foaming and application of the plastic jacket be wound up on a roll again.

With plastic pipes with larger diameters one produces these are best used directly before the one used according to the invention Device by extrusion, so that fiddling with the  No pipes are required. After leaving the used according to the invention Device would be the conduits that are no longer let it roll onto a roll in the thermal insulated conduits of the desired length cut up.

Rigid pipes, e.g. B. steel pipes or other metallic pipes, are preferably used in pieces from 12 to 18 m, which is used shortly before insertion into the invention Device with special plastic sleeves too connected to an "endless strand" and then practically also "endless" continuously foamed and coated will. After the sheathing, the pipes are then attached a special saw in the socket area, d. H. the pipe fittings separated again. The pipe fittings are designed so that after their removal when laying the thermally insulated conduits Release pipe ends without foam insulation so that the line pipes then with usual pipe connectors tightly and permanently connected and then insulated can be.

To create the thermally insulating foam layer you can use any suitable propellant Plastic or the corresponding plastic use forming output components.

Depending on the application, the foam can be thermally insulating Layer more or less flexible or rigid be. For example, the use of flexible foams in cases where the "endless" thermal isolated conduits after leaving the invention used device wound on a roll will. In contrast, it can be an advantage for rigid pipes  be 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 more flexible or rigid type, is the use of a release film necessary, which together with the conduit in the Double form block chain belt system is introduced so that it comes to rest on the mold blocks. The annulus foam is then foamed between the separating film and the conduit.

Any kind of film can be used as a release film, for example those made of 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. B. desires heat reflection or vapor barrier it is advantageous to use a metal foil, e.g. B. one with paper or coated with plastic on one or both sides Insert aluminum foil.

On the other hand, with certain types of foam, e.g. B. in those made of polyethylene or polystyrene, without work with a release film as it may be sufficient if the form block chains with return with a usual Mold release agents are treated. You work with it with mold block chains additionally cooled during the return, so you can even with a suitable procedure achieve that you have a relatively solid, largely homogeneous Surface skin receives, so that, if necessary, even on  the outer plastic protective jacket can be dispensed with can.

The introduction of the foamable mixture into the Annulus between conduit and separating film or form block chains is done in the usual way, for example as it is in DE-OS 33 07 865 is described by the foamable mixture the release film before assembling it into the film tube applies. The setting of the foamable plastic, preferably components A and B to form Polyurethane foams are made so that shortly after Entry of the foamable mixture tubular release film in the double mold block chain Belt system, the foam the annulus between line pipe and separating film and simultaneously the conduit is concentric with the now stable one Foam is held. The necessary for this Measures are known to the person skilled in the art, or can be done without Difficulties are identified.

If desired, when foaming the pipe one or more signaling conductors at a distance from the conduit to be foamed. These reporting heads are used to moisture that has penetrated into the foam layer report and localize.

The method according to the invention naturally allows also the simultaneous foaming of several, pipes insulated from each other, which are then from are surrounded by a common protective plastic sheath. Advantageously, you will have two conduits in a plastic protective sheath and place them against each other isolate, the cross section through such  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, see above that feed and return are housed in one unit, thereby reducing transportation and relocation costs can.

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.

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

Fig. 3 shows a cross section through an inventive thermally insulated line pipe 7.

Fig. 4 shows in cross section a tube connector 12.

In Figs. 1 to 4 and the following discussion, the reference numerals have the following meaning:
1 conduit
2 release film supply roll
3 release film
4 foaming machine
5 double form block chain belt system
5 a , 5 b , 5 a ′, 5 b ′ the mold blocks forming the mold block chain
6 vacuum calibrated extruders
7 thermally insulated conduit
8 the molding channel formed by the molding blocks 5 a , 5 b
9 Frame for guiding the mold block chains
10 thermally insulating foam layer
11 foamed plastic protective jacket
12 pipe connector

In the double mold block chain conveyor system 5 shown schematically in Fig. 2, two mold halves are provided, which are divided lengthways into individual mold blocks 5 a , 5 b , 5 a ', 5 b ', and which are at a conforming speed along a straight line move. The individual mold blocks 5 a , 5 b form tightly pressed together the necessary mold channel and are diverted outside the manufacturing area as separate mold blocks 5 a ', 5 b ' (see Fig. 2) on the guide frame 9 in a conventional manner and returned. The mold blocks 5 a , 5 b can be exchanged for adaptation to the respectively desired diameter of the conduit or the thermally insulating foam jacket 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 to the double mold block chain belt unit 5 together with the separating film 3 unwound from the separating film supply roll 2 , the separating film 3 being provided with the foamed mixture by means of the foaming machine 4 and being 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 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 conduit pipes 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 Also not shown pipe supply and mounting device of the double mold block chain belt 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 power pipes 1 to be insulated are connected one after the other by means of the pipe connectors 12 shown in FIG. 4 and guided through the double form block chain belt system 5 as a quasi-endless strand. 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 the application of the plastic protective jacket 11 , the pipe connector 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 line pipes 7, which are separated again in this way, are fed to the packaging or bundling unit via a storage rack. The cut pipe connecting pieces advantageously remain connected to the thermally insulated conduit pipes 7 until they are installed and are only removed from the conduit 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 connectors 12 , so that these non-sawn pipe connectors 12 can be used again and again after removing the separating film 3 with a protective plastic jacket 11 . The thermally insulated conduits 7 freed from the pipe connectors 12 can then be provided with other protective flaps for transport until installation, 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 (10)

1. A process 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, optionally using a film which acts as a release agent with respect to the device, and is provided with a plastic protective jacket, thereby characterized that one (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 exercises 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 optionally cooled, vacuum-calibrated extruder ( 6 ) by means of an annular nozzle. 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 ( 5 a , 5 b ) of the double mold block chain belt system ( 5 ) one upon entry into the double mold block chain Introduces the belt system ( 5 ) into a tube-shaped separating film ( 3 ), preferably one made of paper, made of aluminum film coated with plastic or paper, or plastic and only then foams the annular space between the conduit ( 1 ) and separating film ( 3 ). 3. The method according to claim 1 and 2, characterized in that the space between the conduit ( 1 ) and separating film ( 3 ) is foamed with a starting mixture forming a polyurethane foam. 4. The method according to claim 1 and 2, characterized in that one uses a blowing agent provided polyolefin, preferably polyethylene or PVC, for the production of the foamed plastic protective jacket ( 11 ). 5. Apparatus for performing 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 machine for the production of polyurethane foams. 7. A thermally insulated conduit ( 7 ), characterized in that the plastic protective jacket ( 11 ) located on the thermally insulating foam layer ( 10 ) consists of a plastic foam with a high density and a smooth closed-cell surface.