DE10165124B3 - Method and device for producing a double-walled thermoplastic pipe with a pipe socket - Google Patents

Abstract

Method for producing a double-walled thermoplastic tube with a tubular sleeve, wherein a) a first tube (1) is extruded into a forming tunnel (4) which is formed from at least one row of molds (5) guided on a web, b) the first tube ( 1) is brought into a corrugated form in at least one first section and is expanded in at least a second section to form a pipe sleeve, c) a second hose (6) is extruded into the first hose and against the wave troughs (8) of the first hose (1 ), d) while the first tube (1) is corrugated and the second tube (6) is extruded into the first, the space (A) between the two tubes (1, 6) is at above atmospheric pressure e) at a predetermined time before or after the beginning of the expansion of the first tube (1) to a pipe sleeve, the space (A) between the two hoses (1, 6) with an over Atm (b) during the extrusion of the second tube (6) into the first tube (1) widened to the tube sleeve, the second tube (6) is pressurized internally is pressurized with atmospheric pressure to a pressure p3 and pressed against the first hose (1), g) then the space (A) is again pressurized between the two hoses with the pressure p1.

Description

The invention relates to a method and an apparatus for producing a double-walled thermoplastic pipe with a pipe sleeve.

Such a method is for example from EP 0 563 575 A2 known. In this case, a first tube is extruded into a forming tunnel, which is formed from at least one row guided on a web molds. The first tube is brought into a corrugated shape in at least one first section and expanded in at least a second section to form a tube sleeve. A second tube is extruded into the first tube and pressed against the troughs of the first tube, so that a composite tube of an outer tube and an inner tube welded thereto is formed. As the first tube is corrugated and the second tube is extruded into the first, the space between the two tubes is pressurized above atmospheric pressure p1. The pressure p1 is so dimensioned that after cooling of the hoses welded together at the troughs of the inner tube between these points is not curved inwards or outwards. After cooling the hoses should set exactly atmospheric pressure.

The introduction of the first tube in the corrugated shape is done by applying a pressure below atmospheric pressure from the outside. The pressure p1 supports the wavy formation of the first tube, but is usually set only relatively low above atmospheric pressure to - as described above - to avoid bulging of the inner tube during cooling of the tubes.

According to EP 0 563 575 A2 the first tube is expanded in the second sections by applying a partial vacuum from the outside to a pipe sleeve. After expanding the first tube to the pipe sleeve, the space between the two hoses is vented to atmospheric pressure.

During the extrusion of the second tube into the first tube expanded to the tube sleeve, the second tube is pressurized from the inside with a pressure p3 above atmospheric pressure and pressed against the first tube. This ensures that a full-surface welding of the two hoses in the area of the pipe socket is achieved.

After the pipe sleeve has been formed through both hoses and the second hose is again extruded against the troughs of the first hose in a further first section thereof, the space between the two hoses is again pressurized with the pressure p1.

The application of the partial vacuum from the outside to the first tube to form a pipe sleeve according to the EP 0 563 575 A2 is difficult in that the space between the first tube and the relevant section of the mold tunnel against the ingress of outside air must be well sealed. If such a seal is not present or only incomplete, the first tube is not expanded exactly over the relevant section of a pipe socket. The required sealing requires complex technical measures.

A similar method for producing a double-walled thermoplastic pipe with a pipe sleeve is also known from WO 95/01251 A1 known.

The invention has for its object to provide a method and apparatus for producing a double-walled thermoplastic pipe with a pipe sleeve, whereby a perfect expansion of the first tube is ensured to a pipe sleeve over the relevant section of the mold tunnel with little effort.

The object is achieved by the features of claim 1. Due to the fact that, at a given point in time before or after the expansion of the first tube to a tube sleeve, the space between the two tubes is subjected to a substantially constant pressure p2 ≦ p1 or variable, but not continuously decreasing, pressure p2 above atmospheric pressure, the the first hose is completely expanded over the designated section of the forming tunnel to form a pipe socket. The application of a partial vacuum from the outside to the first tube to form the tube sleeve, which requires a tight closure of the space between the first tube and the forming tunnel is not required. However, the mold tunnel in the relevant sections, in which the pipe sleeves are formed, have Luftabsaugkanäle. However, these only generate an effective partial vacuum on the outside of the first tube when it rests over the entire section of the pipe sleeve on the forming tunnel.

The pressure p2 is set according to the invention so that the first tube expands exactly in the relevant section to a pipe sleeve. If the pressure p2 is too low, the first hose does not expand or does not expand sufficiently to the pipe socket. On the other hand, if the pressure p2 is too high, the first tube will be stretched during extrusion, so that it will not leak Beginning of the formation of the pipe sleeve a thinner wall thickness and at the end of the pipe sleeve has a thicker wall thickness. Too high a pressure can lead to a tearing off of the first hose during expansion to the pipe sleeve.

The pressure p2 is therefore preferably adjusted so that the first tube is fully expanded over the second section to form a tube sleeve and has a substantially equal wall thickness over the entire section.

For this purpose, it may be expedient to keep the pressure p2 substantially constant during the formation of the pipe sleeve. In conventional profiles of the forming tunnel in the section provided for the pipe sleeve and the usual wall thicknesses of the first tube p2 smaller p1 is appropriate. If the profile height of the pipe socket recess in the forming tunnel is small and / or the wall thickness of the first hose is large, p2 can essentially correspond to p1. At the end of the formation of the first tube in the Rohrmuffenausnehmung it may be appropriate to set p2 greater p1.

In principle, p2 can be adjusted variably, but not continuously, during the extrusion of the two hoses into the pipe socket recess of the mold tunnel, so that the first hose is completely expanded over the relevant section to the pipe socket. is and has a constant wall thickness.

The pressure p3 applied to the second tube during extrusion into the first tube expanded to the tube sleeve and pressed against the first tube can be increased in steps such that it has a lower value and then a higher value for lifting the second tube. The change in the pressure p3 can be linear, for example, in two stages or at least in the initial phase.

The time of switching of the pressure p1 to the pressure p2 is preferably selected so that when lifting the first tube to the pipe sleeve, the pressure p2 has reached the target value in the space between the two hoses. If the pressure p2 sets in very quickly, the pressure p1 is switched to the pressure p2 immediately before the first hose is lifted to a pipe sleeve. If the pressure p2 does not change until after a certain period of time, the pressure is switched over before the first tube is lifted in accordance with this time.

The switching of the pressure p1 to the pressure p2 at the intended time is preferably carried out as a function of the position of the molds, which are provided with the Muffenausnehmung, relative to the extrusion device with which the first tube in the wave or. Muff shape is extruded.

In order for the second tube to be effectively welded to the first tube, the second tube is subjected to the pressure p3 from the inside at a predetermined point in time before the second tube is extruded in the first tube which is widened to form the tube sleeve.

The time in question may be determined by a predetermined position of the molds, which are provided with the socket recess, relative to the extrusion device.

For controlling the pressures p1, p2 and p3 it can be provided that the taking of a predetermined position of a mold on its path is registered and with the aid of this registration the setting of the pressures p1, p2 and p3 is controlled.

Furthermore, events can be registered with which distances traveled by the molds on the track can be determined, and with the aid of this registration the adjustment of the pressures p1, p2 and p3 can take place.

The device according to the invention for carrying out the method steps described above provides the features of claim 6.

The compressed gas control device connected to the first gas duct may have a pressure regulator with which the pressure of the gas flowing into the space between the two hoses can be controlled.

Instead of controlling or regulating the pressure of the gas flowing into the space between the two hoses, the compressed gas control device can have a flow meter with which the gas volume flowing into the space between the two hoses can be controlled or regulated.

For controlling or regulating the pressure or gas volume, a pressure measuring device may be provided for measuring the pressure prevailing in the space between the two hoses.

To accurately set the pressures p1 and p2 in the space between the two hoses, sensors may be provided for measuring the temperature of the gas present in the space between the two hoses and / or the thermoplastic material of the hoses. The compressed gas control device is preferably designed such that, on the basis of the temperature values, the gas pressure or the required gas volume required to achieve the pressures p1 and p2 can be set.

In a development of the compressed gas control device according to the invention for the two gas channels, a predetermined pressure differential between p1 and p2 can be adjustable and preferably adjustable.

For switching the compressed gas control devices, a mark can be attached to the outside of a mold and a stationary sensor can be provided, with which the mark can be registered on its path in a specific position of the mold. The control device is then equipped with a program with which the circuit of the compressed gas control devices takes place as a function of the registration of the mark by the sensor.

In particular, the mark may consist in a survey or depression on the outside of the mold and be provided as a proximity sensor sensor.

For switching the compressed gas control devices, a pulse generator may be provided which generates pulses whose time difference is dependent on the track traveled within this time difference of the molds. The pulses are registered by the control device, which has a program with which the circuit of the compressed gas control devices takes place as a function of the pulses.

The control device can furthermore be designed in such a way that it can variably set the flow of thermoplastic material extruded through the two nozzles of the extrusion device and / or the speed of the molds on its path.

• 1 einen Längsschnitt durch einen Teil eines Spritzkopfes mit Formtunnel vor der Herstellung einer Rohrmuffe,
• 2 einen Längsschnitt durch einen Teil des Spritzkopfes und des Formtunnels zu Beginn der Herstellung einer Rohrmuffe,
• 3 einen Längsschnitt durch einen Teil des Spritzkopfes und des Formtunnels während des Extrudierens des ersten Schlauchs in die Rohrmuffenausnehmung des Formtunnels,
• 4 einen Längsschnitt durch einen Teil des Spritzkopfes und des Formtunnels während des Extrudierens des zweiten Schlauchs in den zur Rohrmuffe aufgeweiteten ersten Schlauch,
• 5 einen Längsschnitt durch einen Teil des Spritzkopfes und des Formtunnels während der Extrusion des zweiten Schlauchs nach Ausformung der Rohrmuffe durch den ersten Schlauch,
• 6 einen Längsschnitt durch einen Teil des Spritzkopfes und Formtunnels nach der Herstellung der Rohrmuffe,
• 7 eine schematische Darstellung der Steuerung der Drücke p1, p2 und p3 und
• 8 eine Ansicht der Druckgas-Steuereinrichtungen.

Embodiments of the invention are explained below with reference to the drawing. In the drawing show:

• 1 a longitudinal section through a part of a spray head with mold tunnel prior to the production of a pipe sleeve,
• 2 a longitudinal section through a part of the spray head and the mold tunnel at the beginning of the production of a pipe sleeve,
• 3 a longitudinal section through a portion of the spray head and the mold tunnel during the extrusion of the first tube into the Rohrmuffenausnehmung the mold tunnel,
• 4 a longitudinal section through a portion of the spray head and the mold tunnel during the extrusion of the second tube in the first tube expanded to the pipe sleeve,
• 5 a longitudinal section through a portion of the spray head and the mold tunnel during the extrusion of the second tube after forming the pipe sleeve through the first tube,
• 6 a longitudinal section through a part of the spray head and mold tunnel after the production of the pipe sleeve,
• 7 a schematic representation of the control of the pressures p1, p2 and p3 and
• 8th a view of the compressed gas control devices.

The 1 to 6 show the essential sequential process steps in the production of a double-walled thermoplastic pipe with a pipe sleeve.

At the in 1 The step shown is a first tube 1 through a first nozzle 2 in a spray head 3 in a form tunnel 4 extruded and brought in a first section in a corrugated form.

How out 7 shows, the mold tunnel 4 from two rows in a cycle of moving molds 5 educated.

1 further shows that a second hose 6 through a second nozzle 7 of the spray head 3 extruded into the first tube and against the troughs 8th of the first tube 1 is pressed. In the direction of production behind the spray head 3 is a calibration mandrel 9 for the second hose 6 arranged, which may be provided with a (not shown in the drawing) cooling device.

While the first hose 1 is brought into the corrugated form and the second tube 6 against the troughs 8th of the first tube 1 pressed and welded to them, the room becomes A between the two hoses 1 and 6 subjected to a pressure above atmospheric pressure p1. The pressure is generated by a pressurized gas coming from one between the two nozzles 2 and 7 on the spray head 3 arranged first gas channel 10 exit.

The pressure p1 is set so that after cooling the two hoses 1 and 6 in the gaps 11 between the two hoses atmospheric pressure sets, so that the second hose at the junctions with the troughs 8th of the first tube 1 has no bulges.

At the in 2 shown method step has the first nozzle 2 of the spray head 3 the beginning of a pipe socket corresponding Muffenausnehmung 12 in the form tunnel 4 achieved while the second nozzle 7 still opposite to the corrugated wall of form 13 forming section of the mold tunnel 4 located. The one through the first nozzle 2 exiting first hose 1 becomes the production direction end of the socket recess 12 is raised by the pressure p1 is switched to a substantially constant pressure p2 less p1. The pressure p1 in the room A between the two hoses 1 and 6 is sized so that the hose 1 in the subsequent formation to a pipe sleeve over the entire surface against the Muffenausnehmung 12 is pressed and has a constant wall thickness over the entire pipe sleeve.

3 shows a process situation in which the second nozzle 7 of the spray head 3 the beginning of the Muffenausnehmung lying in the direction of production 12 of the mold tunnel 4 has reached while the first hose 1 still in the Muffenausnehmung 12 is extruded. In the room A between the two hoses 1 and 6 will continue to drive with the pressure p2. With the pressure p2 becomes the first hose 1 over the entire surface against the Muffenausnehmung 12 pressed. In the dies of the socket recess 12 existing (not shown in the drawing) Luftabsaugkanäle act on the outside of the first tube 1 only then effective with a vacuum after the hose 1 put on the Muffenausnehmung. In 3 this is the front area in the direction of production. In the area where the through the first nozzle 2 exiting first hose 1 to the socket recess 12 raised, but not yet created against this, there is no for the Muffenausformung the hose 1 sufficient partial vacuum, as through the Luftabsaugkanäle A just in the area between the first hose 1 , the spray head 3 and the forming tunnel 4 incoming air is sucked off. The effective socket forming of the hose 1 So it happens with the help of the pressure p2 in the room A between the two hoses.

How out 3 As can be seen, the pressure p2 is set to be that of the first nozzle 2 extruded first hose 1 to the socket recess 12 is raised, but not so far inflated that too much stretching takes place, resulting in a small wall thickness of the hose 1 in the beginning and middle area of the socket recess 12 and a damming of the thermoplastic material and thus to an increase in the wall thickness at the end remote from the production direction end of Muffenausnehmung 12 leads.

To the second hose 6 with the tube expanded to the pipe sleeve 1 effectively merge at the in 3 illustrated process situation of the second hose 6 from the inside via a second gas channel 14 subjected to a pressure p3 above atmospheric pressure. The pressure p3 is dimensioned in an initial phase so that the second tube 6 easy in the Muffenausnehmung 12 is raised without being stretched too much.

While in 4 shown further phase in which the second tube 6 has expanded to the pipe sleeve, the pressure p3 is increased, so that an optimal fusion of the second tube 6 with the first hose 1 is guaranteed. The pressure p2 in the room A between the two hoses 1 and 6 will continue to be essentially constant. It is important that in the in 3 shown phase, in which both hoses 1 and 6 are formed to the pipe sleeve, the pressures p2 and p3 are controlled or regulated so that a predetermined pressure differential between p2 and p3 is maintained. This results in a uniformly stable fusion of the two hoses 1 and 6 in the area of the pipe socket.

5 represents a subsequent process situation, wherein the first tube 1 again into a section with corrugated form wall 13 is extruded while the second tube 6 is still widened to the pipe sleeve. Here is the room A between the two hoses 1 and 6 still pressurized with p2, while the second hose 6 from the inside with the pressure p3 to the first hose 1 is pressed.

At the in 6 the situation shown is the shape of the pipe sleeve both through the first hose 1 as well as through the second hose 6 completed. The second hose 6 from the inside acting pressure p3 is turned off and the room A between the two hoses 1 and 6 the pressure p1 is again applied in order to smooth as possible, with the troughs 8th of the first tube 1 welded second hose 6 to win after cooling of the thermoplastic material, the second tube 6 through the calibration mandrel 9 even further to a smooth inner wall is formed. The pressure conditions are maintained until, in the further process, a section as described in US Pat 2 is shown present.

During the formation of the first corrugations of the hose 1 , as in 6 represented, the room can A initially be subjected to a higher pressure to the first troughs of the molds 5 optimally filled with thermoplastic material, and then be further worked with a lower pressure p1.

7 shows the control of the pressures p1, p2 and p3 to the first gas channel 10 and the second gas channel 14 connected compressed gas control devices 15 respectively. 16 via a control device 17 for the timing of the compressed gas control devices 15 and 16 ,

A compressed gas for generating the pressures p1, p2 and p3 is via a compressed gas supply 18 the compressed gas control devices 15 and 16 fed. The compressed gas control device 15 serves to generate the pressure p1 and the pressure p2 by the from the mouth of the first gas channel 10 escaping gas in the room A between the two hoses 1 and 6 while the compressed gas control device 16 for generating the second tube 6 from the inside acting pressure p3 through the from the mouth of the second gas channel 14 exiting compressed gas is provided.

The timing of the compressed gas control devices 15 and 16 done by the control device 17 as described below.

As from the in the 1 to 6 shown process steps, the temporal circuit of the pressures p1, p2 and p3 from the position of Muffenausnehmung 12 of the mold tunnel 4 relative to the spray head 3 , in particular to the nozzles 2 and 7 , dependent. In the simplest way, the temporal circuit by non-contact switch before and after the Muffenausnehmung 12 respectively. However, if the pressure setting is to be carried out variably in time and by a regulation, it is expedient to register the taking of a predetermined position within its cycle with a certain mold and to control the timing of the pressures p1, p2 and p3 with the aid of this registration.

For this purpose, on the outside of the mold a brand, z. As an increase or depression on the outside of the semi-mold, be attached, wherein by a stationary sensor 19 , In the present case, a proximity switch, the achievement of the mold in the predetermined position is registrable. The control device 17 has a program with which, depending on the registration of the position by the sensor 19 the circuit of the compressed gas control devices 15 and 16 he follows.

The program of the control device 17 takes into account the given geometry of the circuits forming paths of the molds 5 and in particular the position of the Muffenausnehmung 12 forming molds. Due to the registration of the predetermined position of the mold by the control device 17 For example, the pressures p1, p2 and p3 in the above-described and especially in the US Pat 2 . 3 and 6 be set shown process situations.

The repeated registration of the given position of the mold by the sensor 19 serves as a reset of the control program.

Furthermore, a pulse generator 20 be provided, the pulses of the control device 17 supplies, wherein the succession of two pulses is dependent on the return of a predetermined distance of the molds. The pulse generator can, for. As a function of the rotational speed or the rotational path of a gear that is used to deflect the circulating row of molds 5 serves to generate pulses and to the control device 17 hand off. With the help of the pulses, the distance between the Muffenausnehmung 12 Forming molds of the respective switching positions of the pressures p1, p2 and p3 on the Kokillenbahn and perform the circuit of the pressures, as described above. As the initial registration or reset again serves the sensor 19 ,

With the help of the pulse generator 20 can vary the speed of the semi-molds 5 be taken into account on their cycle path.

The control device 17 may further include means for varying the web speed of the molds 5 with a program that the circuit of the pressures p1, p2 and p3 automatically, ie without registration of machine data, by the return of certain sections of molds 5 dependent, taxes.

In 8th is an embodiment of the compressed gas control devices 15 and 16 to the timing of the pressures p1 and p2 or p3 shown. The pressure gas required to set the pressures p1, p2 and p3 is supplied via the compressed gas supply 18 fed. This is about branches to pressure regulator 21 and 22 connected. Downstream behind the pressure regulators 21 and 22 is the gas pressure exiting from these by pressure gauge 23 respectively. 24 measured and one (in detail in 8th not shown) actuating unit within the pressure regulator 21 and 22 communicated. As the actuators, as out 8th emerges, with the help of the compressed gas supply 18 supplied compressed gas, but operated at a lower pressure value, is a pressure reducer 25 respectively. 26 required, which is manually adjustable in the embodiment shown.

Furthermore, sensors (not shown in the drawing) for measuring the temperature of the room A between the two hoses existing gas and / or the thermoplastic material of the hoses 1 and 6 be provided, with the help of the temperature values to achieve the pressures p1 and p2 in the room A between the two hoses required gas pressure at the outlet side of the compressed gas control devices 15 and 16 is adjustable. The with the pressure regulators 21 and 22 connected control device 17 (in 8th not shown) may further be designed so that by means of the pressure regulator 21 and 22 a predetermined pressure differential between p2 and p3 is adjustable.

LIST OF REFERENCE NUMBERS

1

first hose

2

first nozzle

3

spray head

4

mold tunnel

5

mold

6

second hose

7

second nozzle

8th

trough

9

calibrating

10

first gas channel

11

Space between the two hoses

12

Muffenausnehmung

13

wavy shape wall

14

second gas channel

15

Gas pressure control means

16

Gas pressure control means

17

control device

18

Pressure gas supply

19

sensor

20

pulse generator

21

pressure regulator

22

pressure regulator

23

manometer

24

manometer

25

pressure reducer

26

pressure reducer

A

Space between the two hoses

Claims (15)

Process for producing a double-walled thermoplastic pipe with a pipe sleeve, wherein a) a first tube (1) is extruded into a forming tunnel (4) which is formed from at least one row of molds guided on a web (5), b) the first tube (1) is brought into a corrugated shape in at least one first section and is expanded in at least one second section to form a tube sleeve, c) a second tube (6) is extruded into the first tube and pressed against the troughs (8) of the first tube (1), d) while the first tube (1) brought into the corrugated shape and the second tube (6) is extruded into the first, the space (A) between the two tubes (1, 6) subjected to a pressure above atmospheric pressure p1 becomes, e) at a predetermined time before or after the beginning of the expansion of the first hose (1) to a pipe sleeve, the space (A) between the two hoses (1, 6) with a substantially constant pressure above atmospheric pressure p2 ≤ p1 or variable but not continuously decreasing pressure p2 is applied, f) during the extrusion of the second tube (6) into the first tube (1) which is widened to the tube sleeve, the second tube (6) is pressurized from inside with a pressure p3 above atmospheric pressure and pressed against the first tube (1), g) then the space (A) between the two tubes again with the pressure p1 is applied. Method according to Claim 1 , characterized in that immediately before the expansion of the first tube (1) to a pipe sleeve, the pressure p1 is switched to the pressure p2. Method according to Claim 1 or 2 , characterized in that at a predetermined time prior to the extrusion of the second tube (6) in the expanded tube to the first tube (1) of the second tube (6) from the inside with the pressure p3 is applied. Method according to one of Claims 1 to 3 , characterized in that the receipt of a predetermined position of a mold is registered on its path and with the aid of this registration, the adjustment of the pressures p1, p2 and p3 is controlled. Method according to Claim 4 , characterized in that events with which the distance traveled by the molds (5) on the track can be determined are registered and with the aid of these registrations the setting of the pressures p1, p2 and p3 is controlled. Apparatus for carrying out the method according to one of Claims 1 to 5 with A) a mold tunnel (4) formed from at least one row of molds guided on a web, which has a corrugated mold wall (13) in at least one first section and a socket recess (12) corresponding to the pipe sockets in at least one second section, B) an extrusion device provided with a spray head (3), wherein the spray head (3) has a first nozzle (2) for the extrusion of a first hose (1) in the forming tunnel (4) and in the direction of movement of the molds (5) in the forming tunnel (4) downstream second nozzle (7) for the extrusion of a second tube (6), C) one between the two nozzles (2) and (7) arranged first gas channel (10), and in the direction of movement of the mold (5) of the mold tunnel (4) behind the second nozzle (7) opening out the second gas channel (14), E) connected to the first gas channel (10) compressed gas Control device (15) for generating a pressure p1 and a substantially constant pressure p2 ≤ p1 or variable, but not continuously decreasing, pressure p2 through the compressed gas leaving the mouth of the first gas channel (10) in the space between the two hoses (1) and (6) wherein p1 and p2 are above atmospheric pressure, F) a compressed gas control means (16) connected to the second gas passage (14) for generating an over atmospheric pressure p3 on the inside of the second tube (6) through d G as a pressure exiting from the mouth of the second gas channel (14), G) a control device (17) for controlling the compressed gas control means (15) and (16). Device after Claim 6 , characterized in that the compressed gas control device (15) connected to the first gas channel (10) has a pressure regulator (21) with which the pressure of the compressed gas flowing into the space (A) between the two hoses (1, 6) can be controlled is. Device after Claim 6 , characterized in that the compressed gas control device (15) connected to the first gas channel (10) has a flow meter with which the gas volume flowing into the space (A) between the two hoses (1, 6) can be controlled. Device after Claim 7 or 8th , characterized in that a pressure measuring device for measuring in the space (A) between the two hoses (1, 6) prevailing pressure is provided. Device according to one of Claims 7 - 9 , characterized in that sensors for measuring the temperature in the space (A) between the two hoses (1, 6) existing compressed gas and / or the thermoplastic material of the hoses (1, 6) are provided and with the compressed gas control device (15 ) is adjustable on the basis of the temperature values of the pressure required to achieve the pressures p1 and p2 in the space (A) between the two hoses (1, 6) and the required gas volume. Device according to one of Claims 6 to 10 , characterized in that with the aid of the compressed gas control means (15, 16) for the two gas channels (10 or 14), a predetermined pressure differential between p2 and p3 is adjustable. Device according to one of Claims 6 to 11 , characterized in that on the outside of a mold, a mark is attached and a stationary sensor (19) is provided, with which the mark is registered in a certain position of the mold on its path, and that the control device (17) has a program in which, depending on the registration of the mark by the sensor (19), the circuit of the compressed gas control means (15, 16) he follows. Device after Claim 12 , characterized in that the mark in a survey or depression on the outside of the mold and as a sensor (19) is provided a proximity switch. Device according to one of Claims 6 - 13 , characterized in that a pulse generator (20) is provided which generates pulses whose sequence depends on the travel of a predetermined distance of the molds (5) on their path and forwards them to the control device (17), and the control device (17) has a program with which the circuit of the compressed gas control means (15, 16) takes place in dependence on the pulses. Device according to one of Claims 6 - 14 , characterized in that with the control device by the two nozzles (2, 7) of the extruder respectively extruded stream thermoplastic material, and / or the speed of the molds (5) is variably adjustable on its path.

Images