AT398053B - METHOD AND PIPE CONNECTOR FOR THE CONTINUOUS PRODUCTION OF LAMINATED, THERMALLY INSULATED PIPES - Google Patents

Description

AT 398 053 B

The present invention relates to a process for the continuous production of foamed, thermally insulated conduits for the transport of liquid or gaseous, heated or cooled media, in which the conduit is continuously foamed in a double-mold block chain belt system by applying a foamable plastic mixture, the conduit through the Foam 5 is fixed in position.

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 leading the conduit provided with spacers together with a plastic film tube serving as a protective jacket through a stationary molded tube, the joining and welding together of the edges of the plastic tape to the plastic film tube shortly before being introduced into the stationary molded pipe is done. 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. During the passage through the 75 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 foil 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 tube using an extruder (DE-OS 33 07 865). 20 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 itself if you add an additional lubricant between the outer jacket and the stationary pipe. 25 From DE-OS 30 46 463 a continuous process of the type mentioned above for foaming pipes for heating or air conditioning systems is known, in which the pipe is inserted into a molded sleeve continuously formed from a circulating band with simultaneous supply of the foaming plastic and passes through the double-block block belt conveyor system with the sleeve, after which the sleeve reverts to the belt, thereby releasing the foamed tube. 30 For large diameter pipes that have a relatively high dead weight, these methods have proven to be unsuitable because the pipe does not remain centered in the mold space as it passes through the double-block block belt conveyor system and thus receives an uneven foam shell.

Instead of these continuous processes, a discontinuous process is therefore carried out in practice for pipes with lengths of 6 to 18 m and diameters of 20 to 60 mm, in which the 35 pipe is initially provided with foam-permeable spacers at certain intervals and covered with a relatively thick plastic hose becomes. 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 as a " shape " to serve. 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 tube, 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 procedure is not economical.

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, in an economical manner continuously, while at the same time saving material for the outer jacket and forming an uniform low density foam in the thermally insulating layer.

This object is achieved according to the invention with a method of the type mentioned in the introduction, which is characterized in that for foaming rigid, rigid conduit pipes with larger diameters of preferably 20 to 60 mm and with lengths of 6 to 18 m before applying the foamable Plastic mixture, the line pipes are connected to form an endless strand by means of pipe connection pieces, and that the foamable plastic mixture is set accordingly, so that it is hardened at the latest and has a supporting function for the line pipe if the line pipe would sag due to its own weight , and then foamable plastic is extruded and calibrated on the foamed endless 55 conduit to form a foamed plastic protective jacket with a high density in a manner known per se, whereupon the pipe connections are preferably centered transversely to the longitudinal axis be sawn. 2nd

AT 398 053 B

The continuous procedure possible through the use of the double mold block chain conveyor system allows continuous foaming of the conduit, 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 not only a 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 much 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 mantle are reduced to diffusion tightness and protection against injury during transport and 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 densities of 500 to 800 kg / m3.

Since the method 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 center, all spacers or centering devices, as are necessary in the methods according to the prior art, can be dispensed with. This results in the further advantage that the many cold bridges are eliminated, as a result of which the thermally insulated conduit manufactured according to the invention is further improved and made cheaper.

The method according to the invention is suitable for all thermally insulated line pipes, e.g. those made of copper, steel or plastic.

Plastic pipes of larger diameter are best produced directly in front of the device used according to the invention by extrusion, 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.

The invention also proposes a pipe connector that is particularly suitable for carrying out the method according to the invention, which is characterized in that it is designed as a cylinder with blind bores arranged coaxially on both end faces, the diameter of the blind bores being the outside diameter of the conduit pipes and the outside diameter of the cylinder The inside diameter of the mold channel of the double mold block chain conveyor system corresponds. The pipe connectors are designed so that they release the pipe ends without foam insulation after their removal when laying the thermally insulated conduits, so that the conduits 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.

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 belt 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 the 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 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 on return. If you work with mold block chains 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 may even be possible to do without the outer plastic protective jacket. 3rd

AT 398 053 B

The foamable mixture is introduced into the annular space between the conduit and the separating film or mold block chains in a known manner, for example by applying the foamable mixture to the separating film before it is joined to form the film tube. 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 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 load-bearing 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 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 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 plastic protective 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 explained in more detail below with reference to FIGS. 1 to 4, which represent particularly preferred embodiments. 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 form blocks (5a, 5b, 5a ', 5b' forming the double form block chains of the belt system (5)) 1, 3 shows a cross section through a thermally insulated conduit 7 according to the invention, and FIG. 4 shows a pipe connector 12 in cross section.

1 to 4 and the following explanations, the reference symbols have the following meaning: 1 conduit 2 separating film supply roll 3 separating film 4 foaming machine 5 double mold block chain belt system 5a, 5b, 5a ', 5b' mold blocks forming the mold block chain 6 vacuum-calibrated extruder 7 thermally insulated conduit 8 the form channel 9 formed by the form blocks 5a, 5b frame for guiding the form block chains 10 thermally insulating foam layer 11 foamed plastic protective jacket 12 pipe connector

1 and 2, two mold halves are provided, which are divided longitudinally 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 each other and are diverted and returned outside the manufacturing area as separate mold blocks 5a ', 5b' (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 FIG. 1, a conduit 1 is fed by means of a pipe feed and holding device to the double mold block chain belt system 5 together with a release film 3 unwound from the release film supply roll 2, the release film 3 before entering the double mold block chain belt system 5 the foaming machine 4 is provided with the foamable mixture and formed into a tube. After leaving the double mold block chain conveyor system 5, the conduit 1 (FIG. 3) 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.

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, are replaced by one in FIG

Claims (2)

AT 398 053 B storage rack, not shown, by means of the pipe feed and mounting device, also not shown, 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 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 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 conduits 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 connection pieces 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. 1. Process for the continuous production of foamed, thermally insulated conduits for the transport of liquid or gaseous, heated or cooled media, in which the conduit is continuously foamed in a double mold block belt conveyor system by applying a foamable plastic mixture, the conduit being fixed in position by the foam is characterized in that for the foaming of rigid inflexible conduit pipes with larger diameters of preferably 20 to 60 mm and with lengths of 6 to 18 m before applying the foamable plastic mixture, the conduit pipes are connected by means of pipe connectors to form an endless strand, and that the foamable plastic mixture is set accordingly, so that it is hardened at the latest and has a supporting function for the conduit if the conduit would sag due to its own weight, and on d The foam is then extruded and calibrated to form a foamed plastic protective jacket with a high density in a manner known per se, whereupon the pipe connecting pieces are preferably sawn through in the middle across the longitudinal axis. 2. Pipe connector for performing the method according to claim 1, characterized in that it is designed as a cylinder with coaxially arranged blind bores on both end faces, the diameter of the blind bores the outer diameter of the conduit and the outer diameter of the cylinder the inner diameter of the molding channel of the double mold block chain -th tape system corresponds. Including 2 sheets of drawings 5