DE2532406B2 - Method and apparatus for the continuous production of a pipe from a web of a thermoplastic foam - Google Patents

Description

The point that does not form the longitudinal seam is slit again in the longitudinal direction. To close this Slit, a slide lock or an overlap tape can be attached to the pipe. That The pipe produced in this way is advantageously suitable for use for insulation purposes, with the slot an assembly aid means and the attached fasteners mean that it is easy to close after installation enable the pipe. The tube produced according to the invention is free of tension and in its final state form-fitting.

To carry out the method according to the invention, a device with a rotating Belt for transporting the continuously running web, a forming funnel, a device for Closing the butt joint and a pressing device as well as one acting on the outside of the pipe Heater run out.

Since the first heat treatment carried out leads to a relative softening of the foam sheet, sees the risk of the foam sheet being elongated or stretched during transport. To avoid these disadvantages, the device is designed according to the invention so that the conveyor belt is rough Has surface, in front of the hopper a heating device and after the hopper with a a cooling device equipped molding tube is arranged. On the rough surface of the conveyor belt the foam web now adheres and in this way the foam web is lengthened or stretched avoided and an even transport guaranteed.

According to a further proposal of the invention, the device is designed so that the shaped tube at least at the inlet and outlet end on its upper side with a guide slot is, in which a guide rail can be inserted between the side edges of the shaped tube. To the Establishing a perfect connection of the butt joint are means, e.g. B. hold-down plates for deforming of the pipe in an oval cross-section in the area of the device for closing the butt seam intended. In this way it is achieved that the surfaces of the butt joint are perfectly in contact with one another and lateral pressure is exerted on the butt joint.

The invention is shown in the drawing using an exemplary embodiment and is based on this explained in more detail below. It shows

Fig. 1 is a schematic representation of a device for making pipes from a foam sheet,

F i g. 2 shows a schematic cross section through the heating device according to section AA according to FIG. 1,

3 shows a schematic view of the shaped tube according to section BB according to FIG. 1, 5;

4 shows a schematic view through the connecting device according to section C-C according to FIG. 1 and

FIG. 5 is a schematic view of the pressing device, section DD according to FIG. 1.

With the device shown in FIG. 1 f> o are foam strips 2 from a web of a thermoplastic and deformable material that is on Supply rolls 1 are wound up, processed into tubes. The strip 2 runs from the supply roll t over the Deflection roller 3 on the work table 4, on which z. B. a *> "> Gluing device 5 is provided. This gluing device 5 is required for endless joining the strip 2 when changing rolls. From the work table 4, the strip 2 runs through the pair of guide rollers 6, where it runs onto the endless conveyor belt 8. The conveyor belt 8 takes on the driver function for the strip 2, for this purpose the conveyor belt 8 has a very rough top, e.g. B. as with Emery tape with any grain size. This conveyor belt 8 has good mechanical adhesion to the Strip 2 on. This is important because the subsequent heat treatment of the strips is more mechanical Loss of strength and otherwise there would be the risk that it would not be transported evenly or that it would be stretched would. The endless conveyor belt 8 is with the strip 2 through the various devices out and is deflected at the end of the pressing device 20 and back to the tension roller 17 Guide roller pair 6 returned. The drive for the conveyor belt 8 takes place via the drive roller 22.

After the strip rests on the conveyor belt 8 and is transported, the strip passes through the heating device 7, see also the schematic cross section according to FIG. 2. The heating device can with Air, radiators, etc. are operated. When passing through the strip becomes one-sided, i. H. on his later The inside of the pipe is heated and put into the thermoplastic state, with the heating only so far over the thick cross-section of the strip penetrates that the back, the later tube outside, is practical still remains cold and unplasticized and the mechanical transport and adhesion to the belt 8 allows. The heating temperature and the heating time depend on the properties of the foam and the thickness of the strip. This is a total of plasticization, i. H. a warming up in the thermoelastic or transition to the thermoplastic state up to about half the thickness of the Strip desirable, the plasticization must not go so far that the foam structure gets destroyed. This heat treatment, which the strip carries out as it passes through the heating device 7 experiences, corresponds approximately to tempering. The conveyor belt 8 runs here over the worktop 13. The The boiler room is shielded by the side shielding plates 9, so that even heating is also possible of the strip is ensured in the edge areas.

The strip 2, which is partially heated until it is plasticized, becomes after leaving the heating device 7 the device for forming in the Roh.'querschnitt supplied. Here the strip 2 runs into the Form funnel OK, which reshapes it to the pipe cross-section. At the For mtrichter 10 directly closes the Form tube 14, but the top side at least in the inlet area and also at the outlet end with the Guide slot 14a is formed, as also from the schematic cross section according to FIG. 3 can be seen. In this guide slot 14a engages at least in the inlet area the guide rail 12, which at the same time into the Butt seam of the shaped tube 2a engages and marks this strip, so that a twisting of the shaped Pipe is avoided in the subsequent further transport. The forming tube 14 is also with the Cooling device 11 is provided, cooling air being blown into the molding tube 14. That way is ensures that the strip formed into the tube 2a as it passes through the forming tube 14 cools down again to room temperature and solidifies. The tape 18 is also inserted into the forming tube 14 and adapts to the rounding of the shaped tube, whereby a pressure of the shaped tube 2a on the

Conveyor belt 8 is exercised, so that a proper transport despite the friction in the forming tube takes place. The width of the conveyor belt 8 can be significantly smaller than the width of the strip 2, for example, a quarter to a third of the same. At the end of the tube 14 can still Be arranged guide rollers 16, but this is not absolutely necessary and depends on the foam tube to be produced. However, it is also useful to have a guide rail on the top in the run-out area 15 to be provided, which engages in the butt seam of the shaped tube 2a and a twisting of the Pipe prevents.

This is also important so that the butt weld of the pipe is always in the same place Fomrohr leaves and in this position the following device for closing the butt seam can be fed.

The still open formed tube 2a can now be subjected to further treatments, such as welding the butt seam, gluing the butt seam, wrapping with a film with an adhesive edge, welding on a slide fastener, etc. In the embodiment shown, a welding device 19 closes for welding the butt seam of the formed Tube 2a, as can also be seen from the cross section according to FIG. In order to achieve perfect welding of the butt joint, the preformed tube 2a is guided between an upper and lower hold-down plate 18a, b , which press the tube into an oval cross-section, the long axis of the ellipse being arranged horizontally. The butt seam of the shaped tube 2a is on the top, so that the heating blade of the welding device 19 engages in the butt seam and plasticizes the surfaces so that they weld. Furthermore, laterally adjustable guide supports 36 are provided as side delimitation. In this compressed oval cross-sectional shape, the tube 2b welded shut at the butt seam is inserted directly into the pressing device 20, which holds the tube in the specified position over a specified distance until the weld seam is solidified. At the end of the pressing device, the tape 8 is pulled off the pipe 2b and returned to the exit, while the pipe 2b is transported further to the subsequent heating device 24 by means of the guide rollers 23.

5 shows a cross-section through the pressing device 20, the oval cross-section of the pipe 2b welded shut at the butt seam 35, which is on the one hand by the adjustable lateral limit 21 and on the other hand by the upper and lower band 20a, b of Pressing device 20 is held.

The guide rollers 23 that of the pressing device

ίο 20 are arranged downstream, can at the same time take on the task of rounding the oval tube up again by pressing on the side. Then follows the second Heizeinrich device 24, which carries out the outside temperature of the pipe 2b. When passing through the heating device 2 ', the tube is heated on its outer surface until the outer skin is plasticized, but only for a short time, so that the foam structure is retained. As a result of this heat treatment, the last stresses remaining in the pipe in the outer layer are annealed out, so that no stresses remain in the pipe which want to restore it to the flat strip. After leaving the heating device 24, the tube is cooled down again, it being guided, for example, through the cooling tube 27. The cooling pipe 27 can be operated, for example, by means of cooling air which is returned via the inlet 26. In front of the cooling pipe 27, a screen 25 is expediently arranged, which ensures that the cooling air is fed in properly. The cooling tube 27 can be exchangeable and its diameter can be adapted to the respective tubes to be produced. The further removal of the pipe takes place via the take-off rollers 29, which are driven by the drive 31 and the swiveling driver roller 28 on the top side a point that does not correspond to the butt seam, slit in the longitudinal direction. To cut the slotted tube 2c to length, the guide 32, for example a guide bushing, is provided, to which the transverse cutting knife 33 is connected. The deflected pipe sections are placed on the tilting device 34 for storage.

For this purpose 3 sheets of drawings

Claims (4)

Patent claims: 1. A process for the continuous manufacture of a tube from a sheet of a thermoplastic Foam by shaping the web transversely to its longitudinal extension to the pipe cross-section and Connecting the side edges and then briefly heating the outside of the pipe, thereby characterized in that the undeformed path on its later the inside of the pipe forming side briefly heated to the thermoelastic or thermoplastic state and then deformed and cooled before joining the side kranks. 2. The method according to claim 1, characterized in that the tube after the external heat treatment cooled and preferably at a point that does not form the longitudinal seam, back in Slotted lengthways. 3. Device for performing the method according to one of claims 1 and 2 with a revolving belt for transporting the continuously running web, a forming funnel, a device to close the butt joint and a pressing device as well as one on the outside of the pipe acting heating device, characterized in that the conveyor belt (8) has a rough surface in front of the forming funnel (10) a heating device (7) and after the mold funnel (10) a cooling device (11) equipped shaped tube (14) is arranged. 4. Apparatus according to claim 3, characterized in that the shaped tube (14) is formed at least at the inlet and outlet end on its upper side with a guide slot (14a,) in which a guide rail (15) to between the side edges of the shaped tube (2a) is insertable. 10 15th 20th 25th 30th 35 40 The object of the invention relates to a method and an apparatus for continuous Making a tube from a sheet of thermoplastic foam by molding the sheet transversely to its longitudinal extent to the pipe cross-section and connecting the side edges and then brief heating of the outside of the pipe. Pipes made of foam, thin-walled or thick-walled with smaller or larger diameters especially for insulation purposes against cold or heat, e.g. B. for the entire sanitary installation such as Hot water, cold water, sewage, heating pipes, cooling pipes, etc. are used. Such pipes can either extruded directly from foam. However, it is also possible to use such tubes made of foam strips to manufacture. The latter is particularly suitable for foams that are not directly let extrude. The foam strip is here as a web product either by extrusion with Post-foaming, for example in the case of cross-linked polyethylene foams or produced using a coating process, the latter z. B. with soft PVC foam. It is known to make tubes from strips of deformable TV> to produce thermoplastic foams that the foam strips are bent and flat folded up, the butt seam being welded or glued. The resulting The high cross-section is then pressed on (DE-OS 19 15 768). The pipes made in this way However, strips do not have a round cross-section, but tend to have an oval cross-section, which is In particular, it proves to be disadvantageous when used as an assembly aid in a later slitting of the shaped tube the split seam diverges, d. H. is not form-fitting. Furthermore, there is also the risk that due to the tensions remaining in the formed pipe, the glued or welded seam is partly restored rises, is partly not positively connected. In addition, the known method cannot be used Manufacture thick-walled pipes with smaller pipe cross-sections, as creases form due to material compression occurs and no round cross-sections can be achieved. The invention is based on the object of creating a tube made of a foam web, in which also relatively thick-walled pipes made from sheets of greater thickness, even with small pipe cross-sections can be. The tube should also be stress-free after the completed shaping, see above that the form-fit is retained even when the pipe is subsequently further processed and in use. This object is achieved according to the invention in that the undeformed web on its later the The side forming the inside of the pipe briefly reaches the thermo-elastic or thermoplastic state heated and then deformed and cooled before joining the side edges. These heat treatments, which corresponds approximately to a tempering, is carried out so that the heating is only about one Part of the thickness of the cross-section of the web penetrates, the plasticization being driven only so far that the foam structure is not destroyed. The heating temperature and the heating time depend on the Material of the foam and according to the foam thickness. The one provided according to the invention in stages Heat treatment leads to a stress-free tube, which even after it is later cut open (Longitudinal slits) no longer strives to return to its original strip shape. It is further with the method according to the invention of forming in the thermoelastic / thermoplastic State possible, even relatively hard foams still into pipe bodies with relatively small ones To shape inner diameters or to achieve small pipe diameters with thick walls. The intended first heat treatment does not only apply to the side that will later form the inside of the pipe the web is tension-free, but at the same time facilitates the forming into the pipe cross-section. After this Forming into the pipe cross-section, cooling is carried out at the same time, so that the formed pipe can freeze when passing through a mold and become dimensionally stable. Then the reshaped and by cooling again solidified tube pressed in a known manner into an oval cross-section, the long ellipse axis horizontally and at the upper end of the vertical short ellipse axis that by welding or gluing butt seam to be connected is arranged. That way it becomes a flawless concern of the Allows butt seam along its entire surface and thus a perfect connection can be achieved. As a further process step, the invention provides that the tube after the external heat treatment and preferably on one