DE3530187C2 - Method and device for producing thermally insulated conduits - Google Patents

Description

The present invention relates to a method and a pre direction for the continuous production of a thermal insulated conduit with a plastic protective jacket for Transport of liquid or gaseous, heated or cooled Media in which you continuously foam around the pipe Lich in a tubular from a double form block chain Belt system formed cavity with simultaneous foaming introduces centrically in the axial direction, the tube through the Foam is fixed in place, and with a protective plastic jacket provides.  

Process for both continuous and discount Nuclear production of thermally insulated pipe pipes, the outside with a protective jacket made of plastic are known.

For example, according to DE 30 29 106 C2 in continuous Licher way of working a foam on the pipe to be insulated fabric sheath with different densities using a Extruded cross head nozzle, taking the different Sealing the foamed thermoplastic foam layer by cooling the outer surface of the extrusion dated foam layer generated.

Another continuous process, the is described in DE 28 03 708 B2, is generated on the pipe to be isolated by coextrusion at the same time Foam insulation layer and an outer, not foamed Plastic protective jacket, in both cases thermoplastic Plastics are used.

Furthermore, DE 30 06 545 A1 describes a method for the production a pipe with at least two polyurethane foam layers different density known, in which on a rotating Pipe, which is guided lengthways past spray nozzles, the foamable polyurethane mixtures are sprayed on in succession become.

Other 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 tube extruded using an extruder be (DE 33 07 865 A1).

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 initially 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 sheath, 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 foam 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 line pipes with larger 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 those specified in the characterizing part of claim 1 Characteristics in association with those of the generic term.

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 25 03 425 C3.

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, therefore the core was additionally along its entire length provided with a load-bearing mounting plate that radially in the form channel between the oppositely arranged 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 is in this regard the statements in DE 25 03 425 C3 cited above, Column 3, lines 49 ff. Because of the problem of the aforementioned mandrel deflection is therefore used in another known system according to DE 21 65 584 B2 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 that the whole facility is very complicated and is very prone to failure.

Due to the use of such double form block chain conveyor systems in connection with the production of elongated slits Foam insulation pipes experience gathered, 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 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 downstream of 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 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 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 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 dispensed with, as a result of which the one produced according to the invention thermally insulated pipe continues is significantly improved and cheaper.  

The 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 connected to an "endless strand" and then practically also "endless" continuously foamed and coated become. After the sheathing, the pipes are then attached a special saw in the socket area, d. H. of 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 then the line pipes 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.  

In the production of rigid polyurethane foams is the use of a release film necessary 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 advantageous to use a metal foil, e.g. B. one with paper or coated with plastic on one or both sides Insert aluminum foil.  

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 described in DE 33 07 865 A1 is described by the foamable mixture the release film before assembling it into the film tube applies. The setting of components A and B to form the Rigid 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 pipe 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 jacket 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 pipe
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. 1, two mold halves are provided, which are divided lengthways into individual mold blocks 5 a, 5 b, 5 a ', 5 b' and which move along a straight line at a conforming speed . 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 casing to be produced.

According to the present invention, rigid, non-flexible conduit pipes 1 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 pipe feed and holding device, also not shown the double mold block chain conveyor system 5 together with the release 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 an almost 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 in this way, 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, one 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 removal of 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 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 (4)

1. A process for the continuous production of a thermally insulated conduit with a protective plastic jacket for the transport of liquid or gaseous, heated or cooled media, in which the conduit pipe to be foamed is continuously in a tubular cavity formed by a double mold block chain belt system with simultaneous foaming in leads axially in the center, the tube being fixed in position by the foam, and provided with a protective plastic sheath, characterized in that

• (a) as thermally insulated conduits ( 1 ) rigid, non-flexible conduits with larger diameters, preferably those with diameters of 20 to 60 mm and lengths of 6 to 18 m used, which are connected by pipe connectors ( 12 ) and as quasi continuous strand through the double-chain form block Bandan location are guided (5), wherein the introduction of the guide to be insulated pipes in the form of channel of the double mold block chain conveyor system (5) by means of a Rohrzu and -halterungsvorrichtung takes place,
• (b) uses a rigid polyurethane foam system as a foamable plastic mixture, which is set so that it is hardened at the latest and has a function for the conduit ( 1 ) if the conduit ( 1 ) would sag due to its own weight , wherein before the foaming of the intermediate space between the conduit ( 1 ) and the mold blocks ( 5 a, 5 b) of the double block block belt conveyor system ( 5 ) one formed into a tube when entering the double block block belt conveyor system ( 5 ) Separating film ( 3 ), preferably one made of paper, aluminum foil coated with plastic or paper or plastic, and only then foams the annular space between the conduit ( 1 ) and separating film ( 3 ),
• (c) on the foamed conduit ( 1 ) after leaving the double block block belt conveyor system ( 5 ) with a possibly cooled, vacuum-calibrated extruder ( 6 ) by means of an annular nozzle extruded a foamed Kunststoffman tel ( 11 ) with a high density and then
• (d) sawing through the pipe connectors in the middle transverse to the longitudinal axis.

2. The method according to claim 1, characterized in that one uses a blowing agent provided polyolefin, preferably polyethylene, or PVC for the production of the foamed plastic protective sheath ( 11 ). 3. Apparatus for performing the method according to claim 1 and 2, characterized by a known, with a foaming machine ( 4 ) provided double mold block chain conveyor system ( 5 ), before its entry a pipe supply and holding device, optionally with a pipe straightening tool, and after its exit an optionally cooled, vacuum-calibrated extruder ( 6 ) with an annular nozzle for producing the foamed plastic protective jacket ( 11 ) is arranged. 4. The device according to claim 3, characterized in that the foaming machine ( 4 ) is a 2-component mixing machine of poly urethane foams.