DE9321573U1 - Device for the continuous production of a composite pipe with a pipe socket - Google Patents

Description

Device for the continuous production of a composite pipe with pipe socket

The invention relates to a device according to the preamble of claim 1.

EP 0 108 598 B1 discloses a method and a device for producing a composite pipe of the generic type, in which the outer tube is pressurized from the inside with compressed gas and is thereby pressed into ring-shaped mold recesses in the half-molds. The inner tube is pressed against the corrugation of the outer tube via the wall of a tempering bell and welded to it. To form a pipe sleeve in the continuous pipe string, the outer tube is pressed into a cylindrical, smooth-surfaced sleeve recess in the half-molds. The inner tube is formed parallel with an appropriate distance. Then, while the inner tube and outer tube are still hot-plastic, one of the two tubes is pierced and then mechanical pressure is exerted against the inner tube from the inside so that it is pressed against the outer tube and welded to it. The design effort for such a device is considerable. In addition, practice has shown that this does not allow for reliable welding and the precise production of a pipe socket.

PCT WO 90/14208 discloses a method for producing composite pipes, whereby an outer tube is pressed into annular mold recesses in the half-molds, without this being specified in detail. An inner tube is pressed into the inner surface of the tube by means of a

practiced partial vacuum is held on a tempering bell and welded to the outer hose in the known manner. To produce sleeves, the inner hose is pressurized with compressed gas from a gas channel located downstream of an inner nozzle and pressed against the outer hose over its entire surface and welded to it. A defined connection between the inner and outer hose is not guaranteed in this case.

From EP 0 385 465 A2 a method for producing composite pipes with a molded-on sleeve is known, wherein a normal corrugated composite pipe is upgraded to a sleeve at one end and wherein the corrugation at the other end is reduced to a spigot end.

PCT WO 88/05377 discloses a generic device for producing a composite pipe with a molded-on sleeve, in which an outer tube is drawn into the ring-shaped mold recesses of the half-molds by means of a partial vacuum and in which an inner tube is welded in sections to the corrugated outer tube. To form a pipe sleeve, a sleeve recess is formed in at least one pair of half-molds, into which the outer tube is sucked. When the outer tube has already been completely formed into a pipe sleeve, the inner tube is pressed against the outer tube by means of compressed air and welded to it. For this purpose, a tempering bell is provided with an annular gas channel at a considerable distance behind an inner nozzle that extrudes the inner tube. This is pressurized with compressed gas when the entire pipe sleeve already formed from the outer hose and the section of the inner hose to be deformed for this purpose are on the tempering bell during

This design does not ensure that the welding of the inner hose and the outer hose in the area of the pipe socket is carried out reliably.

The invention is based on the object of creating a device for the continuous production of composite pipes with pipe sockets, whereby a high strength of the pipe socket is ensured with little effort.

This object is achieved according to the invention by the features in the characterizing part of claim 1. The combination of, on the one hand, blowing gas at a slight excess pressure compared to atmospheric pressure into the space between the outer hose and inner hose during the manufacture of the normal corrugated composite pipe, while this space is vented during the expansion of the outer hose and inner hose to form the pipe socket, whereby the pressing of the inner hose against the outer hose in the socket area occurs by applying pressure from the inside of the inner hose, ensures that a full-surface welding of the inner hose and outer hose is achieved. This is particularly important because the pipe sockets have to meet particularly high strength requirements, which are particularly difficult to meet because in the area of the pipe socket the pipe does not derive the high strength and rigidity from the corrugated design as a composite pipe.

The subclaims reflect advantageous and partly inventive embodiments of the device according to the invention. The independent adjustability of the nozzle widths according to claim 5 enables

It is possible to use different wall thicknesses for the outer pipe and the inner pipe and to change these wall thicknesses depending on the application of the pipe to be produced. If, for example, a pipe is required that has to withstand high external pressures, the wall thickness of the outer pipe must be higher; if the pipe is exposed to high output loads from the inside, the inner pipe must be made with thicker walls. The design according to claim 6 and in particular that according to claim 7 ensures that when the nozzle width is adjusted between the associated part of the spray head and the nozzle ring, no frictional forces occur because the nozzle ring does not have to be rotated relative to the spray head. Only the downstream nozzle ring nut is rotated. In this case, a high-temperature-resistant lubricant should be arranged at the connection point of the rotary connection, i.e. in the inner groove. The measures according to claims 5 to 8 and in particular the measures according to claims 6 to 8 can also be used independently of those according to claims 1 to 4 in devices for producing composite pipes without sockets.

Further features, details and advantages of the invention will become apparent from the following description of embodiments with reference to the drawing. It shows:

Fig. 1 is a plan view of a device for producing plastic composite pipes,
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Fig. 2 a vertical longitudinal section through the spray head of the device,

Fig. 3 a longitudinal section through a part of the injection head at the beginning of the production of a pipe socket on a composite pipe,

Fig. 4 is a view according to Fig. 3 at the end of the production of the pipe socket,

Fig. 5 an inner nozzle ring with inner nozzle ring nut at the beginning of its

Assembly,
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Fig. 6 the inner nozzle ring and the inner nozzle ring nut after assembly,

Fig. 7 a cross-section through a half-mould in the area of a socket recess,

Fig. 8 is a partial view of a switching element attached to a half-mould in interaction with switches according to the arrow VIII in Fig. 3,
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Fig. 9 is a section through Fig. 8 along the line IX-IX in Fig. 8,

Fig. 10 shows a modified embodiment of a device with a recess for producing a spigot end on a composite pipe,

Fig. 11 a composite pipe in which on the one hand a spigot end and on the other hand a pipe socket are continuously manufactured,

Fig. 12 a composite pipe in which a pipe socket and a double socket o5 are formed and

Fig. 13 shows a pipe connection with a pipe sleeve designed according to the invention.

As can be seen from Fig. 1, a device for producing plastic composite pipes with transverse grooves has a machine table 1 on which half molds 2 or T are arranged, which are each connected to one another to form two so-called chains 3 or 3'. For this purpose, a tab 5 is hinged to each half mold 2 or 2' in its outer, front area in the production direction 4 by means of a link pin 6, which is attached to the corresponding point of the following half mold 2 or 2', also by means of such a link pin 6. The chains 3, 3' formed in this way are guided at their rear end, seen in the production direction 4, over deflection wheels that serve as so-called inlet rollers 7. As the chains 3, 3' rotate, the individual half-molds 2, 2' are swung into a molding section 9 in accordance with the direction of rotation arrows 8 and 8', in which two half-molds 2, 2' are combined to form a mold pair, with 4 consecutive mold pairs lying close together in the direction of production. In order to achieve rapid closing of the half-molds 2, 2' to a parallel and adjacent position, so-called closing rollers Io are provided, which accelerate the rear ends of the half-molds 2, 2' in the direction of production 4.

In the molding section 9 itself, the adjacent half molds 2, 2' are pressed against each other by means of guide rollers 11, which are rotatably mounted in guide rails 12. The inlet rollers 7 are mounted on the machine table 1 so that they can rotate about axle pins 13. At the front end of the machine table 1 in the direction of production 4, return rollers 14, which also serve as deflection wheels, are rotatably mounted about axle pins 15, around which the chains 3 and 3' are deflected and returned to the inlet rollers 7. As can be seen in Fig. 1, the guide rollers end

strips 12 with guide rollers 11 already by the length of several half-molds 2 or T in front of the return rollers 14, so that the half-molds 2 or 2' can be moved away from each other again parallel to each other and transversely to the production direction 4 before they are pivoted by the return rollers 14 o5.

A toothing 16 is formed on the top of the half-molds 2, 2', whereby the two toothings 16 of the half-molds 2, 2' assigned to each other in pairs are aligned with one another, so that a common drive pinion 17 can engage in this toothing 16 from above, which pushes the half-molds 2, 2' in the molding section 9 as a closed mold through the molding section 9. This drive pinion 17 is driven in the usual way by a motor (not shown) via a drive gear 18, which is fixedly attached to a shaft 19 in a rotationally fixed manner, which in turn carries the drive pinion 17. The shaft 19 is mounted in a bearing block 20, which is supported by spacer prisms 21 relative to the machine table and is firmly connected to the latter by means of screws 22.

On the device shown, plastic pipes 23, namely so-called composite pipes, with, among other things, a transverse profiling, i.e.

with grooves 24 running around its circumference.

The pipes 23 are described in more detail below. For this purpose, an extruder is provided, of which only the injection head 25, which is described in more detail below, is indicated. The device described so far is known, for example from EP-A 65 729 (corresponding to US 4 492 551) and from DE 40 21 564 A1.

The injection head 25 is attached to a connecting part 27 of the extruder (not shown) by means of screws 26. It has a substantially ring-shaped nozzle body 28 to which all essential parts of the injection head are attached. This nozzle body has an annular collar 3o projecting in the production direction 4 concentrically to a common central longitudinal axis 29 of the injection head 25. An inner nozzle mandrel 32 is attached to this annular collar 3o by means of an inner threaded connection 31. An outer nozzle mandrel 34 is attached to the outer circumference of the annular collar 3o by means of an outer threaded connection 33. Finally,

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Again concentric to the axis 29, an outer nozzle casing 35 is attached to the nozzle body 28 by means of an adjusting ring 36 and by means of the screws 26.

o5 The inner nozzle mandrel 32 and the outer nozzle mandrel 34 define an inner channel 37 between them, while the outer nozzle mandrel 34 and the outer nozzle casing 35 define an outer channel 38 between them. The inner channel 37 and the outer channel 38 are - as can be seen in Fig. 2 - connected to an injection channel 39 coming from the extruder.

In order to achieve a constant flow of the plastic melt coming from the extruder into the channels 37,38, a guide cone 4o directed into the injection channel 39 against the production direction 4 is attached to the nozzle body 28.

In the nozzle body 28, the inner channel 37 is penetrated by radially extending inner webs 41 and the outer channel 38 is penetrated by outer webs 42 which also extend radially to the axis 29, so that the nozzle body 28 is actually one part. As can be seen from Fig. 2, the inner channel 37 in the nozzle body 28 extends through the annular collar 3o.

The inner nozzle mandrel 32 is provided with a line channel 43 which runs concentrically to the axis 29 and opens into a chamber 44 in the nozzle body 28. In this line channel 43, a protective tube 45 is arranged concentrically to the axis 29, which is insulated from the inner nozzle mandrel 32 by an air gap 46. The protective tube 45 itself is made of steel.

Supply hoses 47, 48, 49, 50, 51, 52, 53 are guided through the protective tube 45 in the line channel 43. These are guided radially from the outside through the nozzle body 28 into its chamber 44, for which purpose approximately radially running bores 54 are formed in the nozzle body and lead into the chamber 44, which of course pass through the outer webs 42 and the inner webs 41 so that the hoses 47 to 53 do not come into contact with the melt transported in the channels 37 and 38. The hoses 47 to 53 are made of highly heat-resistant plastic, for example polytetrafluoroethylene.

The outer nozzle casing 35 is aligned and fixed by means of adjusting screws 55 mounted in the adjusting ring 36 and extending radially to the axis 29. Gas channels 56 are also formed in the outer nozzle mandrel 34, which extend in the production direction 4 and which are connected to a

o5 feed channel 57 in the nozzle body 28, which extends approximately radially to the axis 29 and passes through the webs 42. The spray head is surrounded by heaters 58, 59 over a large part of its length in order to prevent cooling of the melt coming from the spray channel 39 and guided through the channels 37, 38.

The design of the spray head 25 in the area of its nozzles shown on the right in Fig. 2 is explained below with simultaneous reference to Figs. 3 and 4. An inner mandrel plate 6o which widens in the direction of production 4 in the shape of a truncated cone is arranged on the inner nozzle mandrel 32 and carries an inner mandrel designed as a tempering bell 62. This inner mandrel plate 6o delimits an inner nozzle 63 that ends the inner channel 37 on the side radially inward to the axis 29. An extension part 64 is attached to the outer nozzle mandrel 34 by means of a threaded connection 65, which partially surrounds the inner mandrel plate 6o as seen in the production direction 4 and thus surrounds an expanded area of the inner channel 37 on the outside, up to the inner nozzle 63. This is delimited on the radially outer side by means of an inner nozzle ring 66 that is arranged on the extension part 64. The structure and adjustment are described in more detail below.

The inner mandrel plate 6o is arranged on a support tube 68 which runs concentrically to the axis 29 and is connected to the inner nozzle mandrel 32 by means of a threaded connection 61. The inner mandrel plate 6o is supported by means of a conical surface 69 on a corresponding conical seat surface 7o at the free end of the inner nozzle mandrel 32. On this conical seat surface 7o, the inner mandrel plate 6o can be slightly adjusted radially relative to the axis 29, whereby an adjusting shoulder 71 can be formed which is in any case smaller than 1 mm, as a rule not larger than 0.5 mm. To adjust the inner mandrel plate 6o, an adjusting conical ring 72 is provided which rests with a conical surface 73 against a conical seat surface 74 on the inside of the inner mandrel plate 6o. While the

Conical surface 69 and the conical seat surface 7o taper when viewed in the direction of production 4, the conical surface 73 and the associated conical seat surface 74 widen when viewed in the direction of production 4. The adjusting conical ring

72 is guided with its cylindrical inner surface 75 on a spherical ring-shaped guide surface 76, the center 77 of which lies in the axis 29.

Pressure adjustment screws 79 rest against a pressure surface 78 of the adjusting cone ring 72 facing away from the cone surface 73. These are adjustable in abutments 8o, which in turn are firmly connected to the support tube 68. By adjusting the adjustment screws 79 differently, only one of which is shown, the adjusting cone ring 72 can be slightly pivoted on the spherical guide surface 76, so that the angle of inclination a of its cone surface 73 is not identical over the entire circumference of the adjusting cone ring 72. As a result, the inner mandrel plate 6o is adjusted eccentrically to the axis 29 at its support by means of the cone surface 69 on the cone seat surface 7o. In order for this to take place to the desired extent, the average inclination of the cone surface is

73 to the axis 29 is 45°; likewise, the inclination b of the conical seat surface 7o to the axis 29 is approximately 45°. The conical surface 69 and the conical seat surface 74 are thus inclined at 9o° to each other.

By adjusting the inner nozzle ring 66 in the direction of the axis 29, the basic width c of the inner nozzle 63 and, to a small extent, a width c that varies over its circumference is set. By the described radial adjustment of the inner mandrel plate 6o, the width c of the inner nozzle 63 is adjusted to a greater extent over its circumference. This can therefore be used to set the width c of the inner nozzle 63 to be exactly the same over its circumference. On the other hand, it can also be used to set it so that it is unequal.

The inner nozzle ring 66 is adjusted by means of an inner nozzle ring nut 81 in the production direction 4 to adjust the width c of the inner nozzle 63. The inner nozzle ring nut 81 has an inner thread 82 which is supported on an outer thread 83 of the extension part 64. The threads 82, 83 are concentric to the axis 29. The inner nozzle ring nut 81 has openings 84 which run radially to the axis 29 and into which a tool can be inserted to rotate the nozzle ring nut 81.

The inner nozzle ring nut 81 is connected to the inner nozzle ring 66 by means of a rotary connection 85 which is immovable in the direction of the axis 29. For this purpose, the nozzle ring nut 81 has an undercut inner groove 86 on its side facing the inner nozzle ring 66. The inner nozzle

o5 ring 66 has an eccentric ring web 87, the center axis 88 of which is offset by an eccentricity e relative to the axis 29. For assembly, the inner nozzle ring 66 is displaced by the eccentricity e relative to the inner nozzle ring nut 81 and pushed into it so that the eccentric ring web 87 comes to rest in the inner groove 86. This unit consisting of the inner nozzle ring 66 and the inner nozzle ring nut 81 is then screwed onto the external thread 83. The inner nozzle ring 66 is guided with its cylindrical inner guide surface 89 on a likewise cylindrical outer guide surface 90 of the extension part 64. When adjusting the gap width c of the inner nozzle 63, only relatively small forces need to be applied to the inner nozzle ring 66 , since the inner nozzle ring 66 does not have to be rotated relative to the outer nozzle casing 35 when adjusted in the production direction 4. In this respect, only extremely small frictional forces occur in this area. In order to reduce the frictional forces in the rotary joint 85 as much as possible, a high-temperature-resistant lubricant is located in the inner groove 86. As can be seen from Fig. 5, 6, the nozzle rings 66 and 91 can be very short in the production direction 4, and significantly shorter than shown in Fig. 3 and 4.

An outer nozzle ring 91 is arranged on the outer nozzle casing 35 and can be adjusted in the direction of the axis 29 by means of an outer nozzle ring nut 92. The design is identical to that of the inner nozzle ring 66 with inner nozzle ring nut 81, so that reference can be made to the previous description of the inner nozzle 63. The outer nozzle ring 91 delimits an outer nozzle 93 on the radially outer side, the width f of which can be changed by the adjustment already described in the direction of the axis 29.

The gas channels 56 open out of the spray head 25 between the outer nozzle 93 and the inner nozzle 63 arranged downstream in the production direction 4.

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The tempering bell 62 has a conventionally designed, essentially cylindrical calibration cylinder 94. This is arranged on a tempering cylinder 95, which is provided with a tempering channel 96 on its outer circumference. This is connected to the temperature control device via a tempering

o5 tel feed channel 97 is supplied with tempering medium, which is fed in via the supply hose 47 and discharged via the supply hose 51. The tempering channel 96 is usually designed as a heating channel, with a cooling channel, not shown, arranged downstream of this in the production direction 4. A thermal insulation 98 is arranged between the tempering bell 62 and the inner mandrel plate 60.

The tempering cylinder 95 is hollow and has a gas chamber 99 in its interior that surrounds the support tube 68 and is connected to the supply hose 50. The gas chamber 99 is connected to the mold chamber 101 via a gas gap channel 100 formed in the separating surface between the inner mandrel plate 60 and the tempering bell 62, which is formed between the half molds 2 and 2' and the spray head 25 with the tempering bell 62. The gas gap channel 100 opens into the mold chamber 101 immediately behind the inner nozzle 63, as seen in the direction of production 4.

As can be seen from Figs. 3 and 4, annular mold recesses 102 are formed in the half molds, of which only half molds 2 are shown in these figures, which are connected to partial vacuum channels 103 in a known manner.

The plastic melt fed by the extruder through the injection channel 39 flows partly through the outer channel 38 to the outer nozzle 93, from which an outer tube 104 is extruded, which, due to the partial vacuum, is placed in the mold recesses 102 to form a tube provided with the transverse grooves 24. After appropriate cooling and solidification, it forms the corrugated outer tube 105 of the tube 23.

Another part of the melt flows through the inner channel 37 to the inner nozzle 63, from which another hose, namely an inner hose 106, emerges, which reaches the calibration cylinder 94. This expands slightly outwards from the inner nozzle 63 in the production direction 4,

until the inner tube 106 reaches the corrugation troughs 24a of the outer tube 104 and is welded to them. After cooling and solidifying, the inner tube 106 forms the inner tube 107 of the composite tube 23.

As can be seen in particular from Fig. 3 and 4, the half molds 2, 2' are designed in such a way that pipe sleeves 108 are formed at predetermined intervals within the endlessly produced composite pipe 23. For this purpose, a substantially cylindrical sleeve recess 109 is formed in a pair of half molds 2, 2', which thus has a smooth cylindrical wall 110. So that the outer hose 104 also lies completely smoothly against the wall 110 in this area, the partial vacuum channels 103 are not only connected to the mold recesses 102 by means of vacuum slots 111 - as with the mold recesses 102 - but are also connected to the sleeve recess 109 by means of vacuum ring slots 112, so that a partial vacuum is exerted on the outside of the outer hose 104 over the entire wall circumference. The details can be seen in Fig. 7.

A transition section 113 is formed between the socket recess 109 and the mold recess 102' leading in the production direction 4. The socket recess 109 can of course also extend over several half molds 2, 2' arranged one behind the other. At the rear end of the socket recess - seen in the production direction 4 - mold grooves 114 are formed, in which internal grooves 115 are formed in the pipe socket 108 for receiving a sealing ring 116 (Fig. 13). A truncated cone-shaped mold section 117 also adjoins, in which an outwardly opening insertion end 118 of the socket is formed. This is in turn followed by a transition section 119, which leads to the next mold recess 102 - trailing in the production direction 4.

In a spatially fixed arrangement with the socket recess 109, a switching element 120 is formed by a rod-shaped extension of a link bolt 6, which - in a manner to be described - controls various valves in order to achieve different pressure levels in the space between the outer hose 104 and the inner hose 106 and/or within the inner hose 106.

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To this end, a mounting bridge 121 is attached to the bearing block 20, which has a mounting arm 122 that extends above the half-molds T in the production direction 4. On this mounting arm 122, switches 123 to be actuated by the switching element 120 are provided.

o5 124, by means of which solenoid valves 125, 125a can be controlled. Furthermore, switches 126, 127 mounted on the mounting arm 122 are actuated by means of the switching element 120, by means of which the drive motor (not shown) can be switched to different speeds. The switches 123, 124, 126, 127 are switched contactlessly - as can be seen from Fig. 3, 4, 8 - with the contactless actuation of the switches 126, 127 taking place by means of a switching cam 128. The switches 123, 124, 126, 127 are adjustably mounted on the mounting arm 122 in the production direction 4, which is indicated by arrows 129. The switches 123, 124, 126, 127 are connected via lines 123a, 124a, 126a, 127a to a control device 125b which processes the signals coming from the switches 123, 124, 126, 127 and sends corresponding control signals to the solenoid valves 125, 125a. The solenoid valves 125, 125a are supplied with compressed air from a pressure source (not shown) at a pressure ρ which is higher than the output pressures ρ of the solenoid valves 125, 125a which will be explained below.

The pressure in the gas gap channel 100 and thus within the inner tube 106 is controlled via the solenoid valve 125, while the pressure in the gas channels 56 and thus in the space between the outer tube 104 and the inner tube 106 is controlled by the solenoid valve 125a.

During the production of the normal corrugated composite pipe 23 in the form shown on the right in Fig. 3, a pressure pl of approx. 1.05 to 1.15 bar, i.e. a slight overpressure of 0.05 to 0.15 bar, is applied to the gas gap channel 100 by the solenoid valve 125. At the same time, a pressure p2 of approx. 1.2 to 1.3 bar, i.e. a likewise slight but higher overpressure of 0.2 to 0.3 bar, is applied to the gas channels 56. The slight overpressure within the inner tube 106 prevents the inner tube 106 from sticking to the calibration cylinder 94 before it is welded to the outer tube 104. The slightly higher overpressure between the outer tube 104 and the inner tube 106 ensures that when the corrugated tubes 24a and 24b cool down, the pressure p2 is increased.

The inner hose 106ynacn is bulged outwards when the hoses 104, 106 are welded together to form the corrugated composite pipe 23. When the hoses 104, 106 cool down, the pressure is exactly atmospheric.

o5 When, at the moment shown in Fig. 3, the transition section 113 comes into the area of the gas gap channel 100, the switching element 120 reaches the first switch 126 - seen in the production direction 4 - which reduces the feed rate of the shape formed by the half molds 2, 2', so that - with the same output of the extruder - more melt is fed to the inner nozzle 63 and the outer nozzle 93 per unit length of the composite pipe 23 to be produced. This leads to the outer tube 104 and the inner tube 106 becoming thicker, as can be seen in particular from Fig. 4. At the same time, the solenoid valve 125a is connected to the atmosphere, so that atmospheric pressure p3 prevails in the space between the outer tube 104 and the inner tube 106 and in particular the air can escape to the outside. At the same time, the solenoid valve 125 is switched from pl to a higher pressure p4 of approximately 1.2 to 1.45 bar, i.e. to an overpressure of approximately 0.2 to 0.45 bar. This presses the inner hose 106 outwards against the outer hose 104. The latter is already drawn against the wall of the socket recess 109 by the partial vacuum of approximately 0.7 to 0.3 bar in the vacuum ring slots 112. The overpressure pressed in through the gap 100 presses from the inside, so that the outer hose 104 and the inner hose 106 are welded together over their entire surface, resting against the wall 110 of the socket recess 109. The total wall thickness in the area of the pipe sleeve 108 is greater than in the corrugated area so that the rigidity and pressure resistance of the pipe sleeve 108 is the same as in the corrugated area. At the end of the manufacture of the sleeve according to Fig. 4, the switching element 120 first reaches the switch 127, which switches the drive motor back to a higher speed so that less melt is fed per unit length of the composite pipe 23 produced. Immediately afterwards, the switch 124 is actuated, which switches the solenoid valves 125 and 125a back to the conditions described above with the pressures pl and p2. The pipe section 130 produced in the transition section 119 is cut out.

Fig. 10 shows a variant in which a spigot end is produced instead of a pipe socket, which has a smaller outer diameter and is designed to be inserted into a socket or other pipe connection element. In this case, instead of a socket

o5 recess, a spigot end recess 131 is provided in the respective half mold or 2', the diameter of which is only twice the wall thickness of the spigot end 132 to be produced compared to the diameter of the calibration cylinder 94. When the spigot end recess 131 runs over the gas gap channel 100, the solenoid valve 125 is to be switched by the switch 123 in such a way that it is connected to the atmosphere. The solenoid valve 125a is simultaneously switched - as in the manufacture of the sleeve - so that it is open to the atmosphere, so that here too the air can be pushed out from the space between the outer tube 104 and the inner tube 106. The welding of the outer tube 104 and the inner tube 106 is carried out only by pressing the two tubes together between the calibration cylinder 94 and the wall 133 of the spigot end recess 131. Here too, the speed of the mold has been reduced by appropriate control of the drive motor via the switch 126, so that more melt per unit length of the tube to be produced reaches the spigot end 132, so that its wall thickness is greater than the sum of the wall thicknesses of the outer tube 105 and the inner tube 107.

Fig. 11 shows how a composite pipe 23 is continuously manufactured in a pipe string, which has a spigot end 132 and - immediately adjacent to this - a pipe socket 108. The pipe section 134 at the transition from the spigot end 132 to the pipe socket 108 is cut out as waste by two saw cuts 135, 136. As Fig. 11 shows, the spigot end 132 has a slightly tapered insertion cone 137 at its free end. For the continuous production of a composite pipe 23 with a spigot end 132 on the one hand and a pipe socket on the other hand, an additional switch (not shown in the drawing) must be provided, by means of which the solenoid valves 125, 125a change the pressure conditions at the transition from the spigot end 132 to the pipe socket 108 in the manner already shown above.

In Fig. 12, a composite pipe 23 is shown which has a pipe sleeve 108 on the one hand and which - before the renewed transition into the corrugated composite pipe 23 - also has an additional double sleeve 138. This double sleeve 138 is cut out by saw cuts 139, 140 and is suitable as an accessory, i.e. for connecting two composite pipes which do not have a molded pipe sleeve 108. Here too, a piece of pipe 130 is naturally cut out as waste.

In Fig. 12 and 13 it is shown that wart-like projections 141 are formed in a transverse groove 24, by which it is marked how far a composite pipe 23 is to be inserted into a pipe socket 108, so that a firm connection in the area of the pipe socket is ensured.

Claims (9)

1. Device for the continuous production of a composite pipe ( 23 ) consisting of a smooth inner pipe ( 107 ) and an outer pipe ( 105 ) welded thereto and provided with transverse grooves ( 24 ) with a pipe sleeve ( 108 ) 1. wherein half-moulds ( 2 , 2 ') provided with annular mould recesses ( 102 ) and complementing each other in pairs on a moulding section ( 9 ) to form a mould with a central longitudinal axis ( 29 ) are arranged on a machine table ( 1 ) in a circuit and guided in the production direction ( 4 ), 2. wherein the mold recesses ( 102 ) are connected to partial vacuum channels ( 103 ) formed in the half molds ( 2 , 2 '), 3. wherein an injection head ( 25 ) of an extruder is arranged upstream of the molding section ( 9 ), 4. wherein the injection head ( 25 ) is provided with an outer nozzle ( 93 ) for extruding an outer tube ( 104 ) and, downstream in the production direction ( 4 ), with an inner nozzle ( 63 ) for extruding an inner tube ( 106 ) and, at its rear end in the production direction ( 4 ), with a tempering bell ( 62 ), 5. wherein at least one gas channel ( 56 ) opens out of the spray head ( 25 ) between the outer nozzle ( 93 ) and the inner nozzle ( 63 ), and 6. a gas channel ( 100 ) exits from the spray head ( 25 ) between the inner nozzle ( 63 ) and the tempering bell ( 62 ), characterized, 1. that at least one pair of half-moulds ( 2 , 2 ') is provided with a socket recess ( 109 ), 2. that the at least one gas channel ( 56 ) is connected to a valve ( 125 a) which can be switched to gas with pressure (p2) above atmospheric pressure (p3) and to venting, 3. that the gas channel ( 100 ) is connected to a valve ( 125 ) which can be switched to gas with pressure (p4) above atmospheric pressure, and 4. that switches ( 123 , 124 ) are provided which switch the valves ( 125a , 125 ) depending on the position of the sleeve recess ( 109 ) to the gas channel ( 100 ) and/or the at least one gas channel ( 56 ). 2. Device according to claim 1, characterized in that the switches ( 123 , 124 ) are arranged above the forming section ( 9 ) and can be actuated by at least one switching element ( 120 ) connected to a half-mold ( 2 ). 3. Device according to claim 1 or 2, characterized in that the switches ( 123 , 124 ) for actuating the valves ( 125a , 125 ) are assigned switches ( 126 , 127 ) for switching over a drive motor for the half-moulds ( 2 , 2 '). 4. Device according to one of claims 1 to 3, characterized in that at least one pair of half molds ( 2 , 2 ') is provided with a spigot end recess ( 131 ) for producing a spigot end ( 132 ) on the composite pipe ( 23 ). 5. Device according to claim 1, characterized in that the outer nozzle ( 93 ) and the inner nozzle ( 63 ) are adjustable in their width (f, c). 6. Device according to claim 5, characterized in that the outer nozzle ( 93 ) and/or the inner nozzle ( 63 ) have a nozzle ring ( 91 , 66 ) which is guided on the spray head ( 25 ) so as to be displaceable in the production direction ( 4 ) and is adjustable in the production direction ( 4 ) by means of a nozzle ring nut ( 92 , 81 ) engaging in an external thread ( 83 ) on the spray head ( 25 ). 7. Device according to claim 6, characterized in that the nozzle ring nut ( 81 ) and the nozzle ring ( 66 ) are connected to one another by means of a rotary connection ( 85 ). 8. Device according to claim 7, characterized in that the rotary connection ( 85 ) is formed by an inner groove ( 86 ) and an eccentric ring web ( 87 ) engaging therein.