METHOD AND DEVICE FOR MANUFACTURING A TUBE HELVEL FROM A THERMOPLASTIC PLASTIC

Description

TECHNICAL FIELD

[0001] The present invention relates to a method and apparatus for producing a coiled tubing made of a thermoplastic material. In particular, the invention relates to a method and apparatus for producing coiled tubing as connecting lines for, for example, compressed air brake systems, such as those used in large quantities in articulated vehicles or trains. BACKGROUND OF THE INVENTION AND STATE OF THE ART

[0002] Pressure-resistant, flexible polyamide (PA) coiled tubing is standardized as connecting pipe for compressed air brake systems in articulated vehicles and trains (DIN 74 323 with reference to, among others, DIN 74324-1 regarding the tubing material). The subject of the first-mentioned standard is, in addition to dimensions, designations and markings on the finished coiled tubing with kink protection and connections, the materials used for the tubing and connecting parts, their surface properties, the permissible operating pressure and temperature range, the requirements with regard to withdrawal force, recovery behavior, withdrawal force of the screw connections, resistance to kink and tightness, as well as the tests to be carried out to verify compliance with the standardized requirements. Regarding dimensions, the standard specifies a plus / minus tolerance for the outer diameter of the tubing, which takes into account the ovality of the tubing cross-section, which may be caused by the coiling of the tubing, i.e.by the conventional process for producing a tubing coil from a thermoplastic material.

[0003] In the prior art, to produce a coiled tube from a thermoplastically processable polymer, an extruded tube with a predetermined cross-section is usually cut to length, wound helically around a mandrel in a cold state, preferably at room temperature, with the tube's longitudinal axis aligned approximately perpendicular to the mandrel or coil axis, and then subjected to heat setting. Such methods for producing coiled tubes by subsequent shaping through winding and heat setting are known, for example, from US Pat. Nos. 3,021,871 and 3,245,431.

[0004] In order to improve the resilience of the produced coiled pipe compared to this prior art, DE 39 43 189 A1 further proposes a method for producing coiled pipes in which the cut-to-length pipe, while being fed for winding onto the mandrel in the feed direction, is twisted about its longitudinal axis in a direction opposite to the direction of rotation of the coil being formed. Furthermore, DE 39 43 189 A1 teaches that the heat-setting of the extruded pipes, twisted about their longitudinal axis and wound up, is preferably carried out in air or in a liquid medium, which can be a mineral oil, silicone oil, or polydiol bath. The setting time depends on the wall thickness of the pipe and can, for example, be 10 to 15 minutes for 1 mm polyamide and 20 to 30 minutes in air for 2 mm polyamide. As a rule, this heat setting of the tubing coil takes place in a closed oven at a temperature of 120°C to 160°C.

[0005] This multi-step manufacturing process is time-consuming, requires considerable logistical effort, and is also not energy-efficient. First, the thermoplastic material used to extrude the straight tubes must be melted and then cooled back to room temperature. After cutting and coiling, the coiled tube must be heated again as described above to thermally fix the coiled tube.

[0006] The known manufacturing processes described in this regard also have in common that the winding process results in an ovality of the pipe cross-section of the finished pipe coil (see the attached Fig. 15 ), as addressed in the above-mentioned standard, which may not be desirable for certain applications. Furthermore, such a procedure does not allow for the continuous production of a coiled tubing.

[0007] GB 1 518 424 further discloses an alternative method for producing coiled pipes. In this prior art, a pipe is extruded in a first process step, loosely wound, and cooled. In a second process step, the pipe is heated again and formed into a spiral using pairs of guide rollers, with one guide roller arranged inside and one outside the spiral. All guide rollers are driven by a suitable gear. The spiral thus produced, while still hot, is then cooled, supported by support rollers that are also driven by the gear.

[0008] In addition to the high expenditure of time and energy, a disadvantage of this state of the art is seen in particular in the risk that the pipe cross-section of the initially cooled, extruded pipe will deform in an undesirable manner after it has been heated again during winding into a spiral.

[0009] Finally, US Pat. No. 4,929,167 discloses a device for producing spiral pipes from a plastic material, in which a pipe with a round cross-section is first extruded by means of an extruder. The wall thickness along the circumference of the pipe is adjustable so that, after forming the pipe in a device arranged directly behind the extruder for forming the pipe into a spiral, the wall thickness is the same at every point. As described in the Fig. 6As can be seen from this publication, the pipe is extruded in this prior art in such a way that, after the extruder, it has a cross-sectional geometry in which the inner circumference is eccentrically offset relative to the outer circumference. For forming into the spiral, the pipe is then guided through a finishing and cooling sleeve with a circular groove formed by two semicircular grooves in two water-cooled mold halves. As shown in Fig. 1 This publication shows that five support points are provided in the finishing and cooling sleeve, one of which is shown in the sectional view 3-3 according to Fig. 3Accordingly, vacuum passages are formed leading from the circular path, through which a negative pressure can be applied to the pipe from the outside in order to expand the pipe during the forming process and pull it against the wall. Furthermore, the device for forming the pipe includes a roller arrangement arranged behind the mold halves, by means of which the coiled and cooled pipe is conveyed. TASK

[0010] Based on the prior art according to GB 1 518 424, the invention is based on the object of providing a method for producing a coiled pipe from a thermoplastic material that is as simple as possible and addresses the problems mentioned above with regard to the prior art. In particular, the manufacturing method should enable the fastest and most cost-effective (continuous) production of a coiled pipe with a geometrically clearly defined profile cross-section of the pipe, for example, a circular profile cross-section. The object of the invention further includes specifying a device for producing such a coiled pipe that allows the simplest, fastest, and most cost-effective production of the coiled pipe in a continuous production process. PRESENTATION OF THE INVENTION

[0011] These objects are achieved by a method for producing a coiled tubing from a thermoplastic material having the features of patent claim 1 and a device for producing a coiled tubing from a thermoplastic material having the features of patent claim 5. Advantageous embodiments of the invention are the subject of the dependent patent claims.

[0012] A method according to the invention for producing a coiled tubing from a thermoplastic material is characterized in that, after a tubular extrudate has been extruded through an annular die gap of an extruder in a first shaping step, the extrudate which is drawn down from the die gap and is still plastically formable is calibrated in a second shaping step directly following the first shaping step in a forming device to achieve a geometrically defined profile cross-section and is formed into the coiled tubing before the coiled tubing with the geometrically determined profile cross-section solidifies, wherein the calibration of the still plastically formable extrudate in the forming device takes place with the supply of supporting air through a cavity of the extrudate.

[0013] In terms of the device, the invention provides a device for producing a coiled tubing from a thermoplastic material, comprising an extruder with an extrusion head having an annular die gap through which a tubular extrudate can be delivered in a plastically formable state, and a forming device for the further shaping of the plastically formable, tubular extrudate into the coiled tubing with a geometrically defined, calibrated profile cross-section, wherein the forming device is driven and arranged with respect to the pointed head of the extruder such that it can pull the tubular extrudate in the plastically formable state directly down from the annular die gap, and wherein the extrusion head of the extruder has a supporting air bore which opens at an end face of the extrusion head radially within the annular die gap.

[0014] The invention, both in terms of the process and the device, is essentially based on continuously reshaping the plastically formable extrudate drawn down from the die gap immediately after extrusion - i.e. without intermediate cooling / solidification or cutting to length - in such a way that the spiral shape is created at the same time and the profile cross-section of the resulting pipe coil is calibrated in a geometrically defined manner.

[0015] This process makes it possible to produce coiled tubing advantageously in a continuous process, and very quickly. Fewer manufacturing steps are required than with previously known manufacturing processes. Furthermore, less energy is required compared to the previously described state of the art. Overall, the production of coiled tubing is faster and more efficient in terms of time and cost than with the state of the art.

[0016] Furthermore, according to the invention, a geometrically defined, calibrated profile cross-section of the coiled tubing is only created in the forming device, unlike the prior art described above, in which the profile cross-section of the tube is not fully retained as a result of the forming process into a coiled tubing, but rather undergoes deformation (ovality). Thus, the profile cross-section of the coiled tubing produced according to the invention has a new, improved quality with regard to shape and size tolerances.

[0017] For example, the still plastically formable extrudate can be calibrated in the second forming step to achieve a substantially circular cross-section. However, the production of other ring-like cross-sectional shapes, such as corrugated or polygonal ring cross-sections on the coiled tubing, is also possible with high dimensional accuracy, as desired or required.

[0018] With a view to achieving a particularly high degree of dimensional accuracy of the profile cross-section of the produced coiled tubing, the manufacturing process further provides for the calibration of the still plastically formable extrudate in the forming device to be carried out by supplying supporting air through a cavity of the extrudate.

[0019] For this purpose, the extruder's die head has a supporting air bore that opens radially inside the annular nozzle gap at one end face of the die head.

[0020] In a suitable embodiment of the manufacturing process, the still plastically formable extrudate can be pulled down from the die gap by means of the forming device for the second forming step. However, the arrangement can also be such that the pulling down occurs by gravity from a vertically aligned extruder.

[0021] In principle, it is possible for the extrudate to cool and solidify passively in the forming device during the second forming step. However, particularly with a view to rapid process control, it is preferable for the extrudate to be actively cooled in the forming device during the second forming step.

[0022] For active cooling of the extrudate, cold air can be used, for example, which is blown onto the extrudate in the forming device. To ensure particularly good heat dissipation from the extrudate and the forming device, it is preferred to use a liquid coolant, such as water, for active cooling of the extrudate in the forming device.

[0023] For this purpose, a cooling device for discharging a cooling fluid can be provided on the device side in the area of ​​the forming device, by means of which the extrudate conveyed through the forming device can be actively cooled.

[0024] The final assembly of the coiled tubing with regard to length and outlets or connections takes place only after the solidified coiled tubing has left the forming device. This allows the solidified coiled tubing to be cut to a defined length in a first assembly step after leaving the forming device. In a second assembly step, the pre-cut coiled tubing can then be fitted with a kink protection device and / or a connector at one or both ends.

[0025] The assembly steps described above can, but do not have to, be performed by the coiled tubing manufacturer. It is also possible for the continuous coiled tubing to be delivered in a very long piece (or simply cut to a specific length) for (further) assembly, for example, to the manufacturer of end devices such as compressors or air brake systems, where the connectors are then installed, with or without kink protection.

[0026] One possibility for shaping the tubing coil (spiral path and cross-sectional calibration) in the forming device is, for example, to equip the latter with two flexible endless belts, between which the further forming of the extrudate pulled down from the extruder takes place. Both endless belts are designed as forming belts with a groove-like recess extending along the respective belt. One of the endless belts is the inner forming belt and is wound spirally around a rotatable, approximately cylindrical core with a suitable lateral guide, e.g. with three to five turns, in such a way that the groove-like recess points radially outwards. Radially spaced from the rotatable core, for example, two deflection pulleys for the inner forming belt are provided with an axial distance from one another.One deflection pulley guides the inner forming belt to the rotating core, while the other deflection pulley serves to guide the inner forming belt away from the core, so that the inner forming belt rotates in an endless loop around the core and the deflection pulleys. The other endless belt, on the other hand, is the outer forming belt, following the spiral path of the inner forming belt and wound around the inner forming belt with a corresponding form-fitting guide, in such a way that the groove-like recess points radially inwards, towards the core. Another pair of deflection pulleys for the outer forming belt is arranged on the side opposite the core to the deflection pulleys for the inner forming belt and serves in a similar way to guide the outer forming belt in an endless loop towards the rotating core and away from the core.Thus, the inner and outer forming belts with their facing, groove-like recesses form a hollow spiral path for forming the tubular extrudate pulled down from the extruder into the tubular coil with a geometrically determined calibrated profile cross-section.

[0027] Compared to a forming device designed in this way, particularly with regard to high process reliability, a design is preferred in which the forming device has a plurality of rotatably driven forming shafts which are arranged on a rotationally fixed shaft holder in such a way that they form an inner ring of forming shafts and an outer ring of forming shafts, wherein the forming shafts of the inner ring can be driven in the opposite direction to the forming shafts of the outer ring in order to convey the plastically formable, tubular extrudate between the inner ring and the outer ring. In this case, each forming shaft can have a plurality of forming radial grooves with a geometrically defined groove cross-section which are arranged one behind the other at a slight distance from one another along a central axis of the forming shaft. To achieve aThe forming radial grooves of the shaped shafts have a substantially circular profile cross-section; however, other groove cross-section shapes are also possible, depending on the desired or required shape of the profile cross-section of the coiled tube to be produced.

[0028] Preferably, the forming shafts project from the shaft holder at different distances depending on the pitch of the coiled tubing to be produced and / or are tilted with their central axes relative to a central axis of the shaft holder in order to form, with their shaping radial grooves, a substantially spiral path for the plastically formable, tubular extrudate. Alternatively, the radial grooves in the respective forming shaft can be formed at a different axial location and / or an angular tilt of the respective forming shaft can be omitted, so that it runs parallel to the central axis of the shaft holder.The previously mentioned embodiment is preferred, however, because, on the one hand, the forming shafts of the respective ring can be designed cost-effectively as identical parts and, on the other hand, the created, essentially spiral-shaped path for the extrudate runs more evenly, which also promotes easier guidance of the extrudate between the forming shafts.

[0029] Particularly with a view to making the production of the coiled tubing as easy as possible and ensuring high levels of occupational safety during the production of the coiled tubing, a design of the forming device is preferred in which at least one forming shaft of the outer ring is constructed in several parts - more preferably all forming shafts of the outer ring are constructed in several parts - (each) with a shaft stub rotatably mounted in the shaft holder and a shaft segment which can be detachably attached thereto and which has the forming radial grooves of the forming shaft.

[0030] In a particularly cost-effective and simple design, the or each multi-part formed shaft of the outer ring can have a magnetic coupling that releasably holds the shaft segment to the shaft stub. Particular advantages of this type of connection are that the shaft segment can be mounted very easily on the associated shaft stub, and that once a shaft segment has been deflected from its connection to the associated shaft stub, it can automatically return to its original position on the shaft stub. However, other connection solutions with positive and / or frictional engagement, such as a ball catch or a clamp, are also conceivable.

[0031] The shaft segment and the shaft stub of the multi-part formed shaft of the outer ring can further be provided with complementary structures that can be positively engaged with one another for torque transmission. This is more reliable than other torque transmission options, e.g., force or frictional engagement. In an expedient and preferred embodiment with regard to good tiltability of the shaft segment with respect to the associated shaft stub, the complementary structures on the shaft segment and shaft stub can be formed by pins on one part and outwardly open recesses on the other part, which interlock when the multi-part formed shaft of the outer ring is assembled.

[0032] In a simple design of the device, the forming shafts of the outer ring and the forming shafts of the inner ring can be driven by a common drive device. Alternatively, two or more drive devices can be provided to flexibly drive the forming shafts ring by ring or even individually, depending on the respective forming requirements and, if necessary, the different cross-sectional dimensions of the coiled tubes to be produced.

[0033] In a particularly simple embodiment, the common drive device can have a motor which is in drive connection with an input shaft of a radial transfer case, which has output shafts corresponding to the number of forming shafts of the forming device, which in turn are each in drive connection with a forming shaft of the forming device.

[0034] Preferably, the output shafts of the radial transfer case are connected to the forming shafts of the forming device via telescopic universal joint shafts. The advantages of this are that they can be easily adapted to various shaft holders, thus enabling quick tool changes in the forming device. Furthermore, such telescopic universal joint shafts are readily available as commercially available parts.

[0035] In a particularly advantageous embodiment of the device, the radial distributor gear of the drive device can have two gear stages, namely one gear stage for driving the forming shafts of the inner ring and one gear stage for driving the forming shafts of the outer ring. The gear ratios of the gear stages are selected such that different circumferential speeds are established on the forming shafts of the inner ring and the forming shafts of the outer ring in order to convey the extrudate through the forming device with essentially no distortion. Alternatively, it is also possible not to compensate for the necessarily different circumferential speeds on the inner and outer circumferences of the produced coiled tubing due to the different diameters, i.e., not to use gear stages with different gear ratios here.However, this results in some slippage between the forming shafts and the extrudate, which may require slowing down the production of the coiled tubing to avoid damaging the extrudate, making this alternative less preferred.

[0036] In further pursuing the inventive concept, the device can further comprise a coiled tube take-off device downstream of the forming device in the material flow. This device has two take-off rollers extending essentially parallel to one another, which are adapted to support the coiled tube in a rotating manner after it leaves the forming device. This is advantageous, for example, in the continuous production of very long coiled tubes, because the coiled tube take-off device significantly reduces the load on the forming device, especially at relatively fast feed rates for the coiled tube.

[0037] Finally, the coiled tube extraction device can preferably have a rotary drive, by means of which the extraction rollers can be driven in the same direction as the rotation of the coiled tube delivered by the forming device. By selecting a suitable speed for the extraction roller drive, the extraction process of the coiled tube from the forming device can be further supported and smoothed.

[0038] Further features, properties and advantages of the method according to the invention and the device according to the invention for producing a tubing coil from a thermoplastic material will become apparent to the person skilled in the art from the following description of a preferred embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The invention will now be explained in more detail using a preferred embodiment with reference to the accompanying, partially schematic drawings, in which identical or corresponding parts or sections are provided with the same reference numerals. In the drawings: Fig. 1 is a perspective view of an apparatus according to the invention for producing a coiled tubing from a thermoplastic material, viewed diagonally from above / front right, with a view of a tubular extrudate which is discharged in a plastically formable state from an extruder head and is drawn directly through a forming device for further shaping the extrudate into the coiled tubing with a geometrically defined, calibrated profile cross-section; Fig. 2 is a reduced-scale plan view of the apparatus according to Fig. 1, for further illustration of the spatial relative position of the extruder and the forming device of the device; Fig. 3 a front view of the device according to Fig. 1 from below in Fig. 2 and on the scale of Fig. 2 ; Fig. 4 an enlarged front view of the pointed head of the device according to Fig. 1 ; Fig. 5a broken off at the top and bottom, in scale with the Fig. 4 Enlarged sectional view of the pointed head of the device according to Fig. 1 according to the section line VV in Fig. 4 ; Fig. 6 a circumferential sectional view of the pointed head of the device according to Fig. 1 according to the section line VI-VI in Fig. 5 and on the scale of Fig. 5 ; Fig. 7a scaled view of the Fig. 3 enlarged front view of an assembly of the forming device of the device according to Fig. 1in a state separated therefrom, comprising in particular a radial transfer case, which is drivingly connected via an arrangement of telescopic universal joint shafts to forming shafts of the forming device, which in turn are rotatably mounted on a rotationally fixed shaft holder; Fig. 8 a broken-off on both sides, in scale with respect to the Fig. 7 enlarged sectional view of the assembly of the forming device of the device shown there according to Fig. 1 according to the simply angled cutting line VIII-VIII in Fig. 7 ; Fig. 9 a sectional view of the radial distributor gearbox of the device according to Fig. 1 according to the section line IX-IX in Fig. 8, to illustrate the two gear stages of the radial distribution gearbox, with dashed lines indicating the torque curve and arrows indicating the directions of rotation of the individual gears; Fig. 10 a sectional view of the radial distribution gearbox of the device according to Fig. 1 according to the cutting line XX in Fig. 8 , for further illustration of the two gear stages of the radial transfer case, where again the torque curve is indicated by dashed lines and the direction of rotation of the individual gears is indicated by arrows; Fig. 11 a perspective view diagonally from above, on the right side of the shaft holder with the shaped shafts of the Fig. 7 shown assembly of the forming device of the device according to Fig. 1 in a state separated therefrom, wherein in an upper area of Fig. 11the tubular extrudate in the plastically formable state is shown broken off on both sides as it enters the forming device, and arrows indicate the directions of rotation of the individual forming shafts; Fig. 12 a plan view of the Fig. 11 isolated shaft holder with the forming shafts of the forming device of the device according to Fig. 1 , in particular to illustrate a tilting of the shaped shafts with respect to a central axis of the shaft holder and their directions of rotation again indicated by arrows, wherein in an upper area of Fig. 12again, the tubular extrudate entering the forming device, which is in the plastically formable state, is indicated broken off on both sides; Fig. 13 a simply interrupted side view of a tubular coil made of a thermoplastic material produced according to the method according to the invention, which has a circular profile cross-section; Fig. 14 an enlarged sectional view of the tubular coil according to Fig. 13 according to the section line XIV-XIV in Fig. 13 , to illustrate the circular calibrated profile cross-section of the coiled tube; and Fig. 15 a section of the Fig. 14 corresponding sectional view of a coiled pipe made in a conventional manner from a thermoplastic material, to illustrate the resulting, essentially oval profile cross-section of the coiled pipe. DETAILED DESCRIPTION OF THE EMBODIMENT

[0040] In the Figures 1 to 3 A device for producing a coiled tubing RW from a thermoplastic material is designated by the reference numeral 10. The device 10 generally comprises an extruder 12 with an extrusion head 14, which is described in more detail below and which is designed according to the Fig. 4 and 5 an annular nozzle gap 16 through which a tubular extrudate EX can be discharged in a plastically formable state. Furthermore, the device 10 has a forming device 18, also discussed in detail below, for further shaping the plastically formable, tubular extrudate EX into the coiled tube RW with a geometrically defined, calibrated profile cross-section PQ (cf. Fig. 14). Important features of the device 10 are that the driven forming device 18 is arranged with respect to the pointed head 14 of the extruder 12 such that it can pull the tubular extrudate EX in the plastically formable state directly down from the annular die gap 16 of the extrusion head 14, ie immediately before the calibration of the profile cross-section PQ of the pipe and its forming into the pipe coil RW takes place.

[0041] As far as the other components of the device 10 are concerned in general terms, Fig. 1 to 3A cooling device 20 for the coiled tubing RW and a coiled tubing take-off device 22 are also shown. The cooling device 20 of the device 10 is provided in the region of the forming device 18 and serves to discharge a cooling fluid, here water, in order to actively cool the extrudate EX conveyed through the forming device 18. The coiled tubing take-off device 22 of the device 10, on the other hand, is provided downstream of the forming device 18 in the material flow and has two take-off rollers 24 extending essentially parallel to one another, which are adapted to rotatably support the coiled tubing RW after it leaves the forming device 18.

[0042] In the illustrated embodiment, the extruder 12 is a screw extruder, which is mounted on or in a base frame 26 and is known per se, with a screw cylinder 28 for receiving an extruder screw 30 (see the Fig. 1 and 2), which is rotatably mounted via (among other things) a thrust bearing accommodated in a thrust bearing bell 32 (not visible in the figures) and can be driven in rotation by means of a geared motor 34. Near the thrust bearing bell 32, the screw cylinder 28 is provided with a filling opening 36, to which, for example, a filling hopper (not shown) for supplying the plastic material to be processed can be connected.

[0043] The thermoplastic material, in this case, for example, a polyamide (PA), such as PA 12 or PA 6, or alternatively a polyethylene (PE) or polyurethane elastomer (PUR), is melted in the screw barrel 28 or on the extruder screw 30 of the extruder 12 at temperatures that are approximately 20° above the melting point of the respective material. For this purpose, a heating-cooling combination 38 is used, the heating bands of which are arranged on the outer circumference of the screw barrel 28. The reference numeral 40 denotes in the Fig. 1 to 3a cable duct for the energy supply to the heating-cooling combination 38.

[0044] In the screw cylinder 28, the extruder 12 has different functional zones along the extruder screw 30 in a manner known per se, namely a feed zone adjoining the filling opening 36, which merges into a central compression zone, which in turn is followed by an ejection zone ending with the die head 14, through whose die gap 16 the extrudate EX can be drawn down from the extruder 12. For further details of the die head 14, reference is made below to the Fig. 4 to 6 Reference is made.

[0045] The injection head 14 has a base body 42 which is screwed into a central threaded bore 44 of an annular flange part 46, via which the injection head 14 is flanged to the screw cylinder 28. On the outer circumference of the flange part 46, Fig. 4a heating band 48 of the heating-cooling combination 38 can be seen. Here, the injection head 14 is connected to an outlet opening (not shown) of the screw cylinder 28 via a centering ring 50, to which an injection head inlet 52 tapered at the inner circumference is connected, which is received by a spacer ring 54 in a stepped bore 56 of the base body 42.

[0046] At the end of the base body 42 facing away from the flange part 46, a nozzle holder 58 is attached to the base body 42, which, together with the base body 42, defines an interior space 60 for receiving a web mandrel holder 62 and an outer nozzle 64 of the injection head 14. An inner nozzle 66 of the injection head 14 is screwed onto the web mandrel holder 62, which, together with the outer nozzle 64, forms the annular nozzle gap 16 of the injection head 14. An outer diameter of the web mandrel holder 62 is slightly smaller than an inner diameter of the interior space 60 in the region of the base body 42, so that the web mandrel holder 62 can be moved radially in the interior space 60 and thus centered. For this purpose, in the illustrated embodiment, four centering screws 68 are provided which are evenly distributed over the circumference and which are screwed into associated threaded holes in the base body 42 and pass through them in order to come into contact with the outer circumference of the web mandrel holder 62.It will be apparent to a person skilled in the art that the mandrel holder 62 can be fixed in a radial position by means of the centering screws 68 in the interior 60, in which the outer nozzle 64 and the inner nozzle 66 are aligned in order to set an exact circular ring shape of the nozzle gap 16 of the spray head 14.

[0047] According to Fig. 6 The web mandrel holder 62 further has four circular ring-segment-shaped openings 70 separated from one another by webs. The plastically formable extrudate EX, which is fed from the screw cylinder 28 through the injection head inlet 52, the spacer ring 54, and the stepped bore 56 in the base body 42, can be passed through the openings 70 to the annular space between the inner nozzle 66 and the outer nozzle 64 and thus to the nozzle gap 16 of the injection head 14.

[0048] Furthermore, the mandrel holder 62 has a central blind hole 72, which according to Fig. 5via a transverse bore 74 in the mandrel holder 62 with a connecting bore 76 introduced transversely in the base body 42. In addition, the blind bore 72 of the mandrel holder 62 is in fluid communication with a central supporting air bore 78 of the spray head 14, more precisely the inner nozzle 66 of the spray head 14. This supporting air bore 78, in turn, opens at an end face 80 of the spray head 14 radially within the annular nozzle gap 16, as best shown in Fig. 5 This makes it possible to connect a pressure-controlled compressed air source 82 (in the Fig. 1 to 3 indicated schematically) in order to apply a certain internal pressure, e.g. 50 mbar, to the plastically formable extrudate EX drawn down from the nozzle gap 16 via the supporting air bore 78 of the spray head 14.

[0049] Further details of the forming device 18 are particularly Fig. 7 to 12 As best seen in the Figs. 11 and 12As can be seen, the forming device 18 initially has a plurality of rotatably driven forming shafts 84, 86, which are arranged on a rotationally fixed shaft holder 88 in such a way that they form an inner ring 85 of - in the illustrated embodiment six - inner forming shafts 84 and an outer ring 87 of - in the illustrated embodiment also six - outer forming shafts 86, which in Fig. 12 is indicated by dashed lines. Here, the shaped shafts 84 of the inner ring 85 are aligned according to the rotation arrows in the Figs. 11 and 12 driven in the opposite direction to the forming shafts 86 of the outer ring 87 in order to convey the plastically formable, tubular extrudate EX between the inner ring 85 and the outer ring 87. In other words, in the perspective of the Figs. 11 and 12 the driven form shafts 84 of the inner ring 85 each rotate counterclockwise, while the driven form shafts 86 of the outer ring 87 each rotate clockwise.

[0050] In Fig. 12 It is also clearly visible that the formed shafts 84 of the inner ring 85 and the formed shafts 86 of the outer ring 87 are evenly angularly spaced from one another on their respective rings around a central axis 89 of the shaft holder 88, namely by 60° each. The formed shafts 84 of the inner ring 85 are angularly offset by 30° relative to the formed shafts 86 of the outer ring 87 around the central axis 89 of the shaft holder 88, so that each formed shaft 84 of the inner ring 85 sits "on a gap" with respect to the adjacent two formed shafts 86 of the outer ring 87.

[0051] Each forming shaft 84, 86 further comprises a plurality of - in the illustrated embodiment five - forming radial grooves 90 with a geometrically defined groove cross-section 91, which are arranged one behind the other at a slight distance from one another along a central axis 92, 93 of the respective forming shaft 84, 86, as best shown in the Fig. 8 and 11can be seen. In the illustrated embodiment, the shaping radial grooves 90 of the shaped shafts 84, 86 each have a substantially semicircular groove cross-section 91.

[0052] How best to continue in the Fig. 7 , 11 and 12 As can be seen, the formed shafts 84, 86 are arranged and aligned differently with respect to the shaft holder 88 in terms of axial spacing and tilt angle. On the one hand, the formed shafts 84, 86 protrude from the shaft holder 88 at different distances depending on the pitch of the coiled tubing RW to be produced (cf. Fig. 7 the illustration to the right and left of the shaft holder 88). On the other hand, in the illustrated embodiment, the shaped shafts 84, 86 are also tilted with their central axes 92, 93 relative to the central axis 89 of the shaft holder 88 in accordance with the pitch of the coiled tube RW to be produced (see in particular the Figs. 11 and 12 ).

[0053] As a result, the forming shafts 84, 86 with their shaping radial grooves 90 form a substantially spiral path for the plastically formable, tubular extrudate EX. The axial distances and tilt angles of the forming shafts 84, 86 relative to the shaft holder 88 or its central axis 89 are selected such that a section of the extrudate EX conveyed along the spiral path is conveyed or runs in the first radial grooves 90 of the forming shafts 84, 86, as seen from the shaft holder 88, on one revolution around the central axis 89 of the shaft holder 88, before this section of the extrudate EX is transferred to the second radial grooves 90 of the forming shafts 84, 86, as seen from the shaft holder 88, for the second revolution around the central axis 89 of the shaft holder 88, without a step or kink. There, this section is then conveyed further until it is transferred to the next radial grooves 90 of the forming shafts 84, 86, as seen from the shaft holder 88, for the next revolution, etc.; only after passing through the last, here fifth radial grooves 90 of the forming shafts 84, 86 does the extrudate EX, which has solidified into the tube coil RW, leave the spiral path formed by the forming shafts 84, 86, as in . Fig. 7 shown on the right.

[0054] In the illustrated embodiment, the shaped shafts 86 of the outer ring 87 are each formed in several parts, as in Fig. 8 can be seen, with a shaft stub 94 rotatably mounted in the shaft holder 88 and a shaft segment 95 detachably attachable thereto, which has the forming radial grooves 90 of the formed shaft 86. Each multi-part formed shaft 86 of the outer ring 87 has a magnetic coupling 96, which serves to detachably hold the respective shaft segment 95 on the associated shaft stub 94.

[0055] In addition, the shaft segment 95 and the shaft stub 94 of each multi-part formed shaft 86 of the outer ring 87 are provided with complementary structures 97 that can be positively engaged with one another for torque transmission. In the illustrated embodiment, the complementary structures 97 on the shaft stub and segment 94, 95 are formed by two pins 98 on one part (here, the shaft segment 95) and radially outwardly open recesses 99 or axial grooves on the other part (here, the shaft stub 94), which engage with one another when the respective multi-part formed shaft 86 of the outer ring 87 is assembled.

[0056] Furthermore, the rotatable mounting of the one-piece formed shafts 84 of the inner ring 85 in the shaft holder 88, not shown in the drawings, is designed in a similar manner to the mounting of the shaft stubs 94 of the formed shafts 86 of the outer ring 87. Accordingly, the formed shafts 84 of the inner ring 85 extend in a rigid alignment away from the shaft holder 88.

[0057] For the rotary drive of the shaped shafts 84 of the inner ring 85 and the shaped shafts 86 of the outer ring 87, a common drive device 100 is provided in the illustrated embodiment, which is described below with reference to the Fig. 7 to 10 will be described in more detail. Generally speaking, the drive device 100 comprises Fig. 1 to 3a radial transfer case 102, an electric motor 104 for driving the radial transfer case 102, and an arrangement of commercially available telescopic universal joint shafts 106, which establish the drive connection to the forming shafts 84, 86 mounted on or in the shaft holder 88. The radial transfer case 102 is mounted on a frame 103 and thus indirectly supports the remaining components and assemblies of the forming device 18 and the associated drive device 100, as will become apparent from the following description.

[0058] The radial transfer case 102 as the heart of the drive device 100 has according to the Fig. 7 and 8First, an input-side housing half 107 and an output-side housing half 108, which together define an interior space 109 for accommodating the gears 111, 113 of two gear stages 110, 112 of the radial distributor 102, namely a first gear stage 110 for driving the formed shafts 84 of the inner ring 85 (gears 111) and a second gear stage 112 for driving the formed shafts 86 of the outer ring 87 (gears 113). The electric motor 104 of the drive device 100 is flanged to the input-side housing half 107 of the radial distributor 102 via an adapter bell 114. Furthermore, according to Fig. 8 At a central point of the input-side housing half 107, an input shaft 116 of the radial transfer case 102 is rotatably mounted, which is in driving connection with the electric motor 104, more precisely an output shaft (not shown) of the electric motor 104.

[0059] The Fig. 8also shows that the shaft holder 88 is fastened to a central location on the output-side housing half 108 of the radial transfer case 102 by means of a connecting rod 118 and associated fastening means 119 (threaded connection on the output-side housing half 108 / rod shoulder with washer and screw on the shaft holder 88). Around the connecting rod 118, output shafts 120, 121 are rotatably mounted in the output-side housing half 108, corresponding to the number of forming shafts 84, 86 of the forming device 18 - in the illustrated embodiment, a total of twelve. The output shafts 120, 121 are in turn drive-connected to a forming shaft 84, 86 of the forming device 18 via one of the telescopic universal joint shafts 106, as shown in Fig. 8 shown top right and bottom right.

[0060] The Fig. 8It can also be seen that there are longer output shafts 120 and shorter output shafts 121, of which the longer output shafts 120 extend into a first gear plane according to the section line IX-IX in Fig. 8 while the shorter output shafts 121 only extend to a second gear plane according to the section line XX in Fig. 8 In the interior 109 of the radial transfer case 102, the respective associated gears 111, 113 of the first gear stage 110 and the second gear stage 112 are fastened to the output shafts 120, 121 via positive shaft-hub connections with keys, as shown in the Figs. 9 and 10 shown.

[0061] According to the Fig. 8 to 10A central pinion 122 is attached to the end of the input shaft 116 that projects into the interior 109 of the radial transfer case 102, also via a positive shaft-hub connection with a key. The pinion 122 extends axially in the interior 109 across both transmission levels. According to the Figs. 9 and 10the pinion 122 meshes in both gear levels with three larger gears 111 of the first gear stage 110, which are evenly distributed around the circumference with respect to the central axis 89 and for driving the shaped shafts 84 of the inner ring 85, wherein the three larger gears 111 of the first gear level are arranged at an angular offset of 30° around the central axis 89 with respect to the three larger gears 111 of the second gear level. Each of the larger gears 111 of the first gear stage 110 in turn meshes in the respective gear level with a smaller gear 113 of the second gear stage 112 for driving the shaped shafts 86 of the outer ring 87. The three smaller gears 113 of each gear level are also evenly distributed around the circumference in the respective gear level with respect to the central axis 89, and in turn are angularly offset by 30° around the central axis 89 from gear level to gear level.

[0062] The torque distribution from the central input shaft 116 to the various output shafts 120, 121 of the radial transfer case 102 is shown in the Figs. 9 and 10 indicated by dashed lines; arrows mark in the Figs. 9 and 10furthermore the directions of rotation of the various pinions 122 or gears 111, 113. It will be apparent to a person skilled in the art that, due to the different sizes of the gears 111, 113, the gear ratios of the two gear stages 110, 112 of the radial distributor gear 102 are different, as a result of which the forming shafts 84 of the inner ring 85 rotate more slowly than the forming shafts 86 of the outer ring 87. In other words, the gear ratios of the two gear stages 110, 112 are selected such that different circumferential speeds are set at the forming shafts 84 of the inner ring 85 and the forming shafts 86 of the outer ring 87 in order to convey the extrudate EX through the forming device 18 essentially without distortion.This is the case when, viewed in a cross-section of the extrudate EX, every point of the extrudate EX moves around the central axis 89 at essentially the same angular velocity, with radially inner points of the extrudate EX naturally traveling a shorter distance than radially outer points of the extrudate EX. The ratios of the two gear stages 110, 112 of the radial distributor gear 102 take this into account in such a way that the circumferential velocity radially outside the extrudate EX is greater than the circumferential velocity radially inside the extrudate EX.

[0063] As explained above with reference to the Fig. 1 to 3As already mentioned, the cooling device 20 is provided in the area of ​​the forming device 18 of the device 10. In the illustrated embodiment, the cooling device 20 comprises a water basin 124 mounted on the frame 103. Water can be pumped from the water basin 124 by means of a pump (not shown) and fed through a nozzle holder 126 to a plurality of Fig. 1 shown nozzles 128 mounted on the nozzle holder 126.

[0064] The five nozzles 128 of the cooling device 20 in the illustrated embodiment are according to Fig. 1 are essentially radially aligned with respect to the central axis 89 and cover an angular range of approximately 120° around the central axis 89. As far as the axial position of the nozzles 128 is concerned, these are located according to the Fig. 2 and 3in the immediate vicinity of the shaft holder 88, so that they are able to release water onto the extrudate EX already in the area of ​​the first radial grooves 90 of the forming shafts 84, 86 as seen from the shaft holder 88.

[0065] The Fig. 1 to 3Finally, further details of the coiled tube take-off device 22 mentioned above can be found. Accordingly, the coiled tube take-off device 22 has a rotary drive 130, by means of which the take-off rollers 24 can be driven in the same direction of rotation, counter to the direction of rotation of the coiled tube RW delivered by the forming device 18. For this purpose, in the illustrated embodiment, the rotary drive 130 has an electric motor 134 mounted on a frame part 132, which is connected to the take-off rollers 24 via a belt drive 136, which includes pulleys at the motor output and at the ends of the take-off rollers 24, as well as a toothed belt running between them.By a suitable adjustment of the speed of the electric motor 134 of the rotary drive 130, the take-off rollers 24 of the pipe coil take-off device 22 can be driven at a respective peripheral speed which corresponds to the peripheral speed on the outer circumference of the pipe coil RW conveyed from the forming device 18 or is even slightly greater than the latter, so that the pipe coil RW experiences a certain tension when leaving the spiral path between the forming shafts 84, 86 with contact with the take-off rollers 24 perpendicular to the profile cross-section PQ.

[0066] It will be apparent to those skilled in the art that the above-described device 10 can be used to carry out a method for producing a coiled tubing RW from a thermoplastic material, in which two shaping steps follow one another directly. Generally speaking, (1) in a first shaping step, the tubular extrudate EX is extruded through the annular die gap 16 of the extruder 12, whereupon (2) in a second shaping step, directly following the first shaping step, the extrudate EX drawn down from the die gap 16 and still plastically formable is calibrated in the forming device 18 to achieve the geometrically defined profile cross-section PQ and formed into the coiled tubing RW before the coiled tubing RW solidifies with the geometrically defined profile cross-section PQ. The latter has, in terms of dimensional and form accuracy, very low dimensional and form tolerances compared to the state of the art described at the beginning (see also the 。 Figs. 14 and 15 in comparison). In the illustrated embodiment, the still plastically formable extrudate EX is pulled down directly from the die gap 16 of the extruder 12 for the second forming step in the forming device 18 of the apparatus 10 by means of the forming device 18 specially driven for this purpose.

[0067] Due to the special design of the injection head 14 of the device 10 with the supporting air bore 78 connected to the compressed air source 82, the calibration of the still plastically formable extrudate EX in the forming device 18 is also carried out with the supply of supporting air through a cavity HR (see the Figs. 11 and 12 ) of the extrudate EX.

[0068] During the second forming step for producing the tubing coil RW with the geometrically defined, calibrated profile cross-section PQ, it is also possible to actively cool the extrudate EX in the forming device 18. In the exemplary embodiment shown, a liquid coolant, namely water, is used for the active cooling of the extrudate EX in the forming device 18. This liquid coolant is released from the cooling device 20 onto the extrudate EX conveyed through the forming device 18. The water sucked in from the water basin 124 passes via the nozzles 128 attached in alignment to the nozzle holder 126 directly onto the extrudate EX conveyed through the forming shafts 84, 86. Since the forming device 18 is positioned above the water basin 124 of the cooling device 20, the water released onto the extrudate EX drips or flows back into the water basin 124 in a circuit.Additional measures (not shown in the figures) may be provided at the water basin 124 to control the temperature of the circulating water, for example compressor cooling.

[0069] The previously described multi-part design of the forming shafts 86 of the outer ring 87 primarily facilitates start-up of the production of the tubular coil RW. During start-up, the shaft segments 95 of the outer forming shafts 86 are not yet mounted on the associated shaft stumps 94. The plastically formable, tubular extrudate EX emerging from the die gap 16 of the extruder 12 is placed directly around the forming shafts 84 of the inner ring 85, each rotating about its own central axis 92, following the ring shape. In doing so, the extrudate EX also follows the pitch resulting from the previously described arrangement or alignment of the forming radial grooves 90 of the forming shafts 84, i.e., it forms a spiral or helix. Due to the water cooling now switched on by means of the cooling device 20, a wrap around the forming shafts 84 of the inner ring 85 following the ring shape is created, whereby the forming device 18 further conveys the extrudate EX.Now, the shaft segments 95 are placed in turn on the associated shaft stumps 94 of the forming shafts 86 of the outer ring 87, and if necessary, the pressure of the supporting air generated by the compressed air source 82 and released into the cavity HR of the extrudate EX via the supporting air bore 78 is increased until the extrudate EX has complete contact with the forming shafts 84 of the inner ring 85 and the forming shafts 86 of the outer ring 87 and consequently forms a round profile cross-section PQ without ovality in accordance with the geometry of the radial grooves 90. In other words, the still plastically formable extrudate EX is calibrated in the second forming step to achieve the essentially circular profile cross-section PQ according to the illustrated embodiment and simultaneously shaped into the helical shape.

[0070] A further advantage of the split formed shafts 86 of the outer ring 87 is the resulting work safety. Since the formed shafts 84 of the inner ring 85 and the formed shafts 86 of the outer ring 87 are arranged according to the arrows in the Figs. 11 and 12 rotate in opposite directions, there is always the risk that, for example, the operator's fingers will be pulled into the space between the forming shafts 84, 86. If this happens, the attached shaft segment 95 can easily deflect with respect to the associated shaft stub 94 due to the split design of the forming shafts 86. This effect is also very helpful during production because, in the event of any thickening in the extrudate EX, the shaft segments 95 can deflect before they automatically return to their starting position due to the provided magnetic couplings 96, so that the forming device 18 is not blocked or even damaged.

[0071] After leaving the forming device 18, the solidified coiled tubing RW is cut to a defined length in a first finishing step. This can be done manually or automatically.

[0072] Thus, a separating or cutting device (not shown) can be provided in the area of ​​the coiled tube take-off device 22 or, viewed in the direction of material flow, behind it—depending on the desired length of the initially continuously produced coiled tube RW. In this device, the coiled tube RW is first pulled apart or spread apart in a suitable manner so that a separating or cutting tool in the form of pliers, scissors, a guillotine knife with a contact or counter-blade, or the like, can be applied to a turn of the coiled tube RW in order to separate or cut the coiled tube RW at a right angle to the pipe run.

[0073] Then, in a second assembly step, the defined cut-to-length coiled pipe RW is provided with a kink protection KS and / or a connection piece AS at one or both ends (see the Fig. 13 ). Depending on the type of outlet of the RW coiled pipe - coiled pipe with circumferentially extending coiled pipe ends, coiled pipe with axially extending coiled pipe ends or coiled pipe with combined coiled pipe ends - it may first be necessary to locally heat the RW coiled pipe and then plastically deform it again in order to bend one or both connection ends for an axially extending outlet, as shown in Fig. 13 shown.

[0074] Then, if necessary or desired, the kink protection KS is pushed onto the respective end of the RW coiled pipe. This is usually a metallic coil spring or a tube- or pipe-bend-shaped plastic part with color coding, which tapers towards one end on the inner circumference so that it can be secured onto the RW coiled pipe. Finally, the usually metallic connection piece AS is pressed or driven into the respective end of the RW coiled pipe at room temperature to secure the RW coiled pipe accordingly. Fig. 13 to complete.

[0075] There are also one-piece or pre-assembled, combined kink protection / connection parts (not shown) that can be installed at each end of the coiled pipe in a single operation. The assembly steps described above, with their respective sub-steps – pulling or spreading the coiled pipe RW / separating or cutting the coiled pipe RW / bending the respective coiled pipe end if necessary / attaching the kink protection KS to the respective coiled pipe end if necessary / attaching the connecting piece AS or a combined kink protection / connection part to the respective coiled pipe end – can be carried out fully or semi-automatically, e.g., on a rotary table (not shown).

[0076] In a method for producing a tubing coil from a thermoplastic material, a tubular extrudate is extruded through an annular die gap of an extruder in a first forming step. The extrudate, which is drawn down from the die gap and is still plastically formable, is calibrated in a second forming step in a forming device directly following the first forming step to achieve a geometrically defined profile cross-section and formed into the tubing coil. The tubing coil with the geometrically determined profile cross-section then solidifies. The calibrating of the still plastically formable extrudate in the forming device takes place with the supply of supporting air through a cavity in the extrudate. This method enables continuous production of the tubing coil with a new, high level of quality with regard to dimensional and shape tolerances on the profile cross-section of the tubing coil.Furthermore, a device for producing such a tubular coil is proposed. LIST OF REFERENCE SYMBOLS

[0077] 10Device 12Extruder 14Extrusion head 16Die gap 18Forming device 20Cooling device 22Pipe coil take-off 24Take-off roller 26Base frame 28Screw cylinder 30Extruder screw 32Thrust bearing bell 34Gear motor 36Filling opening 38Heating-cooling combination 40Cable duct 42Base body 44Threaded hole 46Flange part 48Heating band 50Centering ring 52Extrusion head inlet 54Spacer ring 56Stepped hole 58Nozzle holder 60Interior 62Bar mandrel holder 64Outer nozzle 66Inner nozzle 68Centering screw 70Breakthrough 72Blind hole 74Cross hole 76Connection hole 78Support air hole 80End face 82Compressed air source 84Formed shaft 85Inner ring 86Formed shaft 87Outer ring 88Shaft holder 89Central axis 90Radial groove 91Groove cross-section 92Central axis 93Central axis 94Shaft stub 95Shaft segment 96Magnetic coupling 97Complementary structures 98Pin 99Recess 100Drive device 102Radial distributor gearbox 103Frame 104Electric motor 106Telescopic universal joint shaft 107Input-side housing half 108Output-sideHousing half 109 Interior 110 First gear stage 111 Gear of the first gear stage 112 Second gear stage 113 Gear of the second gear stage 114 Adapter bell 116 Input shaft 118 Connecting rod 119 Fasteners 120 Output shaft 121 Output shaft 122 Pinion 124 Water basin 126 Nozzle holder 128 Nozzle 130 Rotary drive 132 Frame part 134 Electric motor 136 Belt drive ASConnecting piece EXExtrudate HRCavity KSKink protection PQProfile cross-section RWHelix pipe

Claims

1. A method of producing a coiled tubing (RW) from a thermoplastic plastics material, in which in a first shaping step a tubular extrudate (EX) is extruded by way of an annular nozzle gap (16) of an extruder (12) and the extrudate (EX), which is drawn down from the nozzle gap (16) and capable of being shaped plastically, is calibrated and formed into the coiled tubing (RW) in a second shaping step directly subsequent to the first shaping step in a shaping device (18) to achieve a geometrically defined profile cross-section (PQ), before the coiled tubing (RW) with the geometrically defined profile cross-section (PQ) solidifies, wherein the calibrating of the extrudate (EX) capable of being shaped plastically is carried out in the shaping device (18) with the feed of supporting air via a cavity (HR) of the extrudate (EX).

2. A method of producing a coiled tubing (RW) according to claim 1, wherein the extrudate (EX) capable of being shaped plastically is for the second shaping step drawn down from the nozzle gap (16) by the shaping device (18) and / or wherein the extrudate (EX) is actively cooled during the second shaping step in the shaping device (18) and / or wherein the extrudate (EX) capable of being shaped plastically is calibrated in the second shaping step so as to achieve a substantially circularly annular profile cross-section (PQ) and / or wherein the solidified coiled tubing (RW) after leaving the shaping device (18) is cut to length in defined manner in a first making-up step.

3. A method of producing a coiled tubing (RW) according to claim 2, wherein a liquid coolant is used for active cooling of the extrudate (EX) in the shaping device (18).

4. A method of producing a coiled tubing (RW) according to claim 2 or 3, wherein the coiled tubing (RW) cut to defined length is provided in a second making-up step with a kink protection (KS) and / or a connecting member (AS) at one end or both ends.

5. A device (10) for producing a coiled tubing (RW) from a thermoplastic plastics material, particularly by the method according to any one of the preceding claims, comprising an extruder (12) with an injection head (14) having an annular nozzle gap (16) by way of which a tubular extrudate (EX) can be delivered in a state capable of being shaped plastically, and a shaping device (18) for further shaping of the tubular extrudate (EX), which is capable of being shaped plastically, to form the coiled tubing (RW) with a profile cross-section (PQ) of geometrically defined size, wherein the shaping device (18) is driven and so arranged with respect to the injection head (14) of the extruder (12) that it is capable of drawing down the tubular extrudate (EX), in the state capable of being shaped plastically, directly from the annular nozzle gap (16), and wherein the injection head (14) of the extruder (12) has a supporting air bore (78) which opens at an end surface (80) of the injection head (14) radially within the annular nozzle gap (16).

6. A device (10) for producing a coiled tubing (RW) according to claim 5, wherein the shaping device (18) comprises a plurality of rotationally drivable shaping shafts (84, 86) which are so arranged at a shaft mount (88) secure against rotation that they form an inner ring (85) of shaping shafts (84) and an outer ring (87) of shaping shafts (86), and wherein the shaping shafts (84) of the inner ring (85) are drivable in opposite direction to the shaping shafts (86) of the outer ring (87) so as to convey the tubular extrudate (EX), which is capable of being shaped plastically, between the inner ring (85) and the outer ring (87).

7. A device (10) for producing a coiled tubing (RW) according to claim 6, wherein each shaping shaft (84, 86) has a plurality of shape-imparting radial grooves (90) with a geometrically defined groove cross-section (91), the grooves being arranged in succession at a slight spacing from one another as seen along a center axis (92, 93) of the shaping shaft (84, 86), and / or wherein the shaping shafts (84, 86) project to different extent from the shaft mount (88) in correspondence with the pitch of the coiled tubing (RW) to be produced and / or are tilted by the center axes (92, 93) thereof with respect to a center axis (89) of the shaft mount (88) so as to form by their shape-imparting radial grooves (90) a substantially helical path for the tubular extrudate (EX) which is capable of being shaped plastically, and / or wherein at least one shaping shaft (86) of the outer ring (87) is of multi-part construction with a shaft stub (94), which is rotatably mounted in the shaft mount (88), and a shaft segment (95), which can be detachably mounted on the shaft stub and which has shape-imparting radial grooves (90) of the shaping shaft (86), and / or wherein the shaping shafts (86) of the outer ring (87) and the shaping shafts (84) of the inner ring (85) are drivable by a common drive device (100).

8. A device (10) for producing a coiled tubing (RW) according to claim 7, wherein the shape-imparting radial grooves (90) of the shaping shafts (84, 86) have a substantially semicircular groove cross-section (91).

9. A device (10) for producing a coiled tubing (RW) according to claim 7 or 8, wherein the shaping shaft (86), which is of multi-part construction, of the outer ring (87) has a magnetic coupling (96) serving the purpose of detachably retaining the shaft segment (95) at the shaft stub (94), and / or wherein the shaft segment (95) and the shaft stub (94) of the shaping shaft (96), which is of multi-part construction, of the outer ring (87) are provided with structures (97) which are of complementary configuration and which can be brought into interlocking mutual engagement for transmission of torque.

10. A device (10) for producing a coiled tubing (RW) according to claim 9, wherein the complementary formed structures (97) at the shaft segment (95) and shaft stub (94) are formed by pins (98) at one part and outwardly open recesses (99) at the other part, which pins and recesses interengage in the mounted state of the shaping shaft (86), which is of multi-part construction, of the outer ring (87).

11. A device (10) for producing a coiled tubing (RW) according to any one of claims 7 to 10, wherein the drive device (100) has a motor (104) which is in driving connection with an input shaft (116) of a radial transfer transmission (102), which in correspondence with the number of shaping shafts (84, 86) of the shaping device (18) has output shafts (120, 121) which in turn are each in driving connection with a respective shaping shaft (84, 86) of the shaping device (18).

12. A device (10) for producing a coiled tubing (RW) according to claim 11, wherein the output shafts (120, 121) of the radial transfer transmission (102) are in driving connection with the shaping shafts (84, 86) of the shaping device (18) by way of telescopic universal-joint shafts (106) and / or wherein the radial transfer transmission (102) of the drive device (100) comprises two transmission stages (110, 112), namely a transmission stage (110) for drive of the shaping shafts (84) of the inner ring (85) and a transmission stage (112) for drive of the shaping shafts (86) of the outer ring (87), and wherein the translation ratios of the transmission stages (110, 112) are selected in such a way that different circumferential speeds arise at the shaping shafts (84) of the inner ring (85) and the shaping shafts (86) of the outer ring (87) so as to convey the extrudate (EX) through the shaping device (18) substantially free of distortion.

13. A device (10) for producing a coiled tubing (RW) according to any one of claims 5 to 12, wherein a coiled tubing take-off (22) is provided downstream of the shaping device (18) in the material flow, comprising two take-off rollers (24), which extend substantially parallel to one another and which are adapted for the purpose of rotationally supporting the coiled tubing (RW) after leaving the shaping device (18), and / or wherein a cooling device (20) for delivery of a cooling fluid, by which the extrudate (EX) conveyed by the shaping device (18) can be actively cooled, is provided in the region of the shaping device (18).

14. A device (10) for producing a coiled tubing (RW) according to claim 13, wherein the coiled tubing take-off (22) comprises a rotary drive (130) by which the take-off rollers (24) are rotationally drivable in the same direction counter to the rotational direction of the coiled tubing (RW) delivered by the shaping device (18).