DE2405927A1 - DEVICE FOR EXTRUSION OF PROFILES, IN PARTICULAR PIPES, FROM NETWORKED PLASTIC - Google Patents

Description

Herne, 8000 Munich 40,

Freiligrathstrasse 19 n "» »lli» «-« UQelir Eisenacher Strasse 17

P.O. Box 140 WIP I. - I Π _ö . H. Π. O β Π Γ patient app. Betzier

Pat. Herrmann-Trentepohl Dinl-PhVQ Eduard Rptzler Telephone: 363011

Telephone: 5 1013 wi | * i. rnjj. i_uu «iu ν ^ ι & ι ^ ΐ 363012

⁵¹⁰¹⁴ Dipl.-Ing. W. Herrmann-Trentepohi ³⁶³⁰¹³

Telegram address: Telegram address:

Bahrpatente Herne PATENTANWÄLTE Babetzpat Munich

Telex 08 229 853 Telex5215360

~ 1 0 // - If-O ^ r ₇ bank accounts:

Bayerische Vereinsbank Munich 952 Dresdner Bank AG Herne 7-520 499 Postal check account Dortmund 558 68-467

Ref .: _M 04 551 B / h,

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Please send a letter to:

Munich

7th February 1974

PONT-A-MOUSSON S.A., Avenue Camille Cavallier 54 Pont-a-Mousson, France

Device for extrusion of profiles, in particular from tubes, from networked! plastic

The invention relates to a device for extruding profiles, in particular tubes, made of crosslinked plastic.

From FR-PS 1 538 988 a device is already known which has an inlet opening and this opening in a block connected and having a reduced cross-section having channels for the further conveyance of the pressed material, the Channels with an outlet opening are in communication with the shape of the profile, through an arrangement of a mouthpiece and a thorn is intended.

The device can be connected to a feed device for a mixture of a .Kunststoff via its inlet opening and connect a crosslinking agent, e.g. B. with one of the FR-PS 1 538- 988 removable device with a very high Compression works as well as injection of separate and consecutive quantities.

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However, in the known device, the inlet opening is arranged in the direction of the extruder nosepiece-mandrel axis and the conveying channels of reduced cross-section consist of inclined channels extending from the axial opening diverge to open into the channel formed by the extruder nozzle and the mandrel.

There is therefore a cone tip at the point at which the channels separate from the axial opening Production is very difficult and can never be centered exactly despite the most precise processing. This leads inevitably to poor distribution of the material in the channels and consequently to poor quality profiles, in particular in terms of the homogeneity of the profile material in cross-section, in the uniform thickness and finally in the constancy of the dimensions in the longitudinal direction.

The object of the invention is to eliminate these disadvantages and to create a device of the aforementioned type, which is characterized in that the inlet opening into the channels with reduced cross-section via an annular Recess or chamber with the axis of the arrangement of extruder mouthpiece and mandrel opens and the transmission channels are arranged parallel to this axis.

This means that there are no difficulties in manufacture and all channels intended to receive the material to be processed are completely symmetrical in relation to each other arranged on the axis so that there are no irregularities in the distribution of the fed material. In addition, the dimensions of the profiles are completely constant both in the transverse direction and in the longitudinal direction.

According to a further feature of the invention, the channels with the reduced cross-section open into the through the extruder

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mouthpiece-mandrel arrangement formed channel over an annular chamber, the cross-section of which is both larger than that of the forwarding channels as well as that of the channel just mentioned. This chamber creates a kind of compensation or damping effect, in that the throughput of the exiting from it and into the extruder die-mandrel arrangement entering pressed material is very uniform and independent of the injection rhythm at the entrance of the device he follows.

The invention can be particularly advantageous for the extrusion of tubes made of crosslinked plastic such as crosslinked Polyethylene.

Further features and advantages of the invention emerge from the following, non-restrictive example Description and the drawing, which shows an axial section through a device according to the invention shows.

The device consists of a block 1 with a through cylindrical bore 2 with the axis X- X. In this bore a cylindrical part 3 of the same diameter is arranged, which protrudes on one side Has extension 4 with a collar 5 which is fastened to the block 1 by means of a screw 6. On his the other end is the cylindrical part 3 outside the body 1 by one made of the same material Mandrel 7 extended, which initially consists of a frustoconical part 8 and then from a relatively long cylindrical Part 9 consists.

Along the axis Y-Y, which is perpendicular to the axis X-X, the block 1 has a cylindrical blind bore 10, in which a bush 11 is arranged, which merges into a collar 12 on the outside, which with the block 1 by screws is screwed. The bush 11 includes a cylindrical axial

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Chamber 14, which is closed on the side of the collar 12 by a rod 15. In the chamber 14 opens perpendicular to the X-X axes. and Y-Y a supply opening. The rod 15 is fixed to a drive device 15a connected, which the rod in a rapid reciprocating movement of z. B. move 200 to 300 strokes per minute can.

An inlet 17 located in the block 1 connects the bore 10 and in particular the chamber 14 with the cylindrical one Bore 2. At the point where the inlet joins the cylindrical part 3 has an annular recess with the axis X-X, from which, also in the part 3, grooves 19 run parallel to the axis X-X, which in the frustoconical piece 8 of the mandrel 7 open.

The mandrel 7 is surrounded by an extruder mouthpiece 20 which extends over its entire length and with it one forms annular passage or channel, the radial dimension of which is constant over its entire length. The passage has a first part 21 in the form of a pressure reduction chamber which is formed by the frustoconical surface 8 of the dome and an opposite frustoconical surface 22 is limited on the mouthpiece. The chamber extended into a completely tubular part, the passage 23 of which passes through the cylindrical part 9 of the dome and an opposing surface 24 of the mouthpiece is formed. On the side of the block 1, the extruder nozzle a shoulder 25, which on the block by an annular counterflange 26 with angular Cross-section is pressed and fastened with the aid of screws 27. In addition, between the shoulder 25 and the mating surface on the mating flange 26 has a slight radial play in order to precisely center the extruder mouthpiece to enable with the help of adjusting screws 28 which are screwed into the counter flange 26 and against press the shoulder 25.

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The dimensions of the various parts of the device are such that the diameter of the chamber 14, the diameter of the recess 18, the diameter of the Grooves 19, the mean diameter of the chamber 21 and that of the tubular part 23, for example, of the order of magnitude Relation from 1 (chamber 14) to 2.9 (recess 18) to 0.66 (grooves 19) to 2 (chamber 21) to 0.38 (part 23) lie.

In the block 1, parallel to the axis X-X, there are several bores 29 at regular intervals around the bore 2 for receiving of cylindrical heating cartridges 30 are provided. In addition, the cylindrical part 3 with the mandrel extending it a continuous axial channel 31 for receiving a cylindrical heating cartridge 32 inside the cylindrical part 9 of the mandrel. A jacket 33 with heating resistors finally surrounds the cylindrical portion 24 of the extruder die.

If tubes are to be made of cross-linked polyethylene, the device works as follows:

Through the opening 16 opening into the pressure chamber 14, a polyethylene and a crosslinking agent is inserted The mixture is continuously injected into the chamber under very high pressure, which can be up to several thousand bar can, is compressed by the action of the rod 15 reciprocating very quickly. This Compression enables the crosslinking agent to be completely mixed with the polyethylene. The pressed material then flows into the annular recess 18, traverses the axial grooves 19 while forming a layer and then occurs into the chamber 21, from where it passes around the cylindrical heating cartridge 32 in the mouthpiece-mandrel arrangement which it exits in the form of a tube T.

The grooves 19 can be produced easily and precisely and the

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velvet from the recess 18, the grooves 19, the chamber 21 and the part 23 existing arrangement is exactly symmetrical with respect to the axis X-X, so that the tube produced is perfectly homogeneous and uniform.

The pressure generated in the chamber 14 causes a sharp rise in temperature of the injected material to be pressed, connected with a complete mixing of the crosslinking agent with the polyethylene; the reduced cross-section in the Grooves enable the creation of a noticeable back pressure in the recess 18 of the chamber 14, which causes the mixing also favored. The only purpose of the heating cartridges 30 is to maintain the temperature in the chamber, and the grooves 19 must not be too long, so that the triggering of the networking process due to the increased temperature not only at the exit of the grooves or only when the material to be pressed has entered the pressure reduction chamber 21 occurs, begins. However, the grooves also cause the pressed material to be evened out and gelled, i.e. H. the formation of a paste.

Since the pressure reduction chamber 21 has a much larger cross-section (about 5: 1) than the part 23 of the extruder nozzle-mandrel arrangement, there is a kind of damping, so that the throughput entering the part 23 is complete is uniform and independent of the pulses acting on the material to be pressed in the compression chamber. The lingering of the pressed material in the chamber 21 also enables excellent welding of those emerging from the grooves 19 Raw material strands.

The crosslinking reaction starting in the pressure reducing chamber 21 increases and reaches its peak in the tubular Part 23, in the interior of which the heating cartridge 32 is arranged and is practically at the exit outside of the extruder nosepiece-mandrel arrangement closed.

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None of the channels through which the pressed material flows has a dead space, so that any blockage of the pressed material in the device is prevented.

Finally, because of the uniform and unimpeded crosslinking process, a completely homogeneous one can be achieved Make product without pockets from sintered powder.

- Patent claims: -

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Claims (10)

Claims Device for extrusion of profiles from cross-linked Plastic, consisting of a block with an inlet provided in it and connected to the inlet Continuation channels with reduced cross-section, which form the shape of the profile over a channel formed by an arrangement of extruder mouthpiece and mandrel with an outlet opening in connection stand, characterized in that the inlet (17) has an annular recess (18) opens into the reduced cross-section, formed as grooves, continuation channels, which are arranged around the same axis (X-X) as that of the extruder die-mandrel arrangement (20, 2) is, and that the grooves (19) are arranged parallel to this axis (X-X). 2. Device according to claim 1, characterized in that the grooves (19) in the part (23) the extruder mouthpiece-mandrel arrangement (20,7) open out via an annular chamber (21), the cross-section of which both larger than that of the grooves (19) as well as larger than that of the passage (23). 3. Apparatus according to claim 2, characterized in that the passage (23) of the extruder nozzle-mandrel arrangement has a constant diameter over its entire length between the annular chamber (21) and the outlet opening. 4. Device according to one of claims 1 to 3 »characterized in that the grooves (19) a Multiple straight passages parallel to the axis (X-X) of the extruder nozzle-mandrel arrangement (20, 7) 409832/0901 form. 5. Device according to one of the claims. 1 to 4, characterized in that the annular chamber (21) has a substantially frustoconical shape, which of the grooves (19) in the direction of the passage (23) of the extruder nozzle-mandrel arrangement converges. 6. Device according to one or more of claims 1 to 5, characterized by Transverse adjustment elements with respect to the extruder mouthpiece (20) and the mandrel (7). 7. Apparatus according to claim 6, characterized in that the mandrel (7) is firmly connected to the block (1) and the extruder mouthpiece (20) is fixed in the axial direction is mounted on the block (1), but is adjustable in the transverse direction by means of screws (28) Has game. 8. Device according to claims 1 to 7, characterized by heating elements (30) near the grooves (19). 9. Device according to one or more of claims 1 to 8, characterized by Heating means (30) in the vicinity of the passage (23) of the extruder die-mandrel assembly (20, 7). - 10 - 409832/0901 10. Apparatus according to claim 2, characterized in that the ratios the passage cross-sections in relation to the cross-section of the inlet opening (17) each approximately 2: 3 for the grooves (19), 2: 1 for the annular chamber (21) and 2: 5 for the passage (23) of the Ertruder nosepiece-mandrel arrangement be. 409832/0901