DE102010043791A1 - Method for guiding and shaping extruded plastic strand, involves forming air cushion around extrudates, by applying pressured air through inlet provided in the tube head like tool - Google Patents

Abstract

The method involves supplying extrudates (13) in a tube head like tool (2) that is connected with a calibration station (3). The microporous guide elements (11,15) are provided in the calibration station, for guiding extrudates. An air cushion is formed around extrudates, by applying pressured air through an inlet (7) provided in the tube head like tool. Independent claims are included for the following: (1) apparatus for guiding and shaping extruded plastic strand; and (2) calibration case for feeding extruded plastic strand.

Description

The invention relates to a method for guiding extrudates in the plastic extrusion produced in the plastic mass in an extruder, formed in a tool and calibrated and final molded in one or more cooling stations, wherein the extrudate passes in the molded and / or plastically deformable state of sliding surfaces becomes. Furthermore, the invention comprises an associated device.

In the calibration systems known today, the plastic product to be calibrated is sucked to the inner wall of the calibration tool in a calibration device by applying a vacuum. Here are several problems to overcome, the solution usually have complicated devices result. Due to the applied vacuum, a sufficient sealing of the calibration station to the ambient pressure is required, which leads to both a problematic inlet and an outlet situation, since this vacuum system must be open at least on two sides, since the product to be calibrated on one side and on the other side.

Calibration systems of variable cross-section are also used in the calibration DE 10 2004 052 972 in front.

The DE 10 2008 026 682 discloses a method for the production of plastic profiles with an extruder, a downstream in the production direction of the extruder tube head and a calibration station with variable cross-section, in which the plastic profile can be applied to the inner wall of a Kalibrierwerkzeuges.

From the DE 10 2004 052 972 A1 is a wound sheet known to be used in the calibration of extruded plastic pipes. The flat material overlaps in partial areas and lies close together in the overlapping area. A similar device is from the DE 10 2007 026 309 known, also here are parts of each other closely on top of each other. The larger the overlapping surfaces and the larger the contact surfaces of the sheet material to the plastic pipe, the greater the friction occurring.

Object of the present invention is to propose a system in which the forces that are caused by the coefficient of friction are minimized.

The solution of the procedural task is characterized in connection with the preamble of claim 1, characterized in that between the surface of the extrudate and the sliding surface, a fluid cushion is constructed, wherein the fluid cushion is generated by applying fluid and the fluid is passed through the sliding surface, wherein the sliding surface has microporous properties. The extrudate can thus virtually float on a fluid cushion, primarily an air cushion. It can be compared with the function of an air cushion boat, also the pad is greatly minimized the frictional resistance. Depending on the applied pressure, the strength of the air cushion can be regulated and / or controlled. It can thus also fluctuations in production z. B. in the pipe diameter, to be collected.

Advantageously, the pressure is applied equidistantly around the extrudate through the sliding surfaces, whereby a fluid cushion ring is formed. The extrudate is primarily a plastic profile, preferably a plastic tube.

The solution to the device is in connection with the preamble of claim 4, characterized in that with the device, a fluid cushion can be generated on which slides the extrudate, wherein the device comprises a guide member which is fluid-permeable to produce the Fliudpolster on the guide member. So that the guide element is fluid-permeable, this is microporous.

Advantageously, the microporous guide element is arranged so that the fluid cushion can be generated around the circumference and / or along the outer contour of the extrudate.

With such a guide element z. B. a calibration, preferably a Kalibrierhülse be equipped which leads and forms a plastic profile. The friction between the surface of the Kalibrierhülse and the outer contour of the plastic profile, respectively pipe, is thus significantly reduced. The calibration can also be made changeable in the passage cross-section.

It is also conceivable that the end of a nozzle insert of an extrusion die is made with a microporous material. The detachment of the melt from the steel surface can be facilitated. Furthermore, there is the possibility that the melt is already cooled immediately after exiting the extrusion die.

In the drawings, an embodiment of the invention is shown schematically.

1 shows the general structure of an extrusion line and

2 a schematic diagram with the microporous guide elements and

3 a section through a microporous guide element

In 1 is an extruder line with a conventional extruder 1 and a subsequent tool 2 , usually in the form of a pipe head, advantageously also with adjustable mass gap, shown. This is followed by a calibration station 3 at. To this calibration station 3 can become more successor institutions 4 like other spray calibration stations and deduction 5 , and a separator 6 etc. connect.

In 2 is the essence of the invention illustrated reproduced. She shows the exuder 1 , the tool 2 , Parts of the calibration station 3 , which is shown here schematically with a space that is represented as a dashed line. This is a calibration sleeve, not shown, with a microporous guide element 11 and 15 as well as in the tow stopper 9 , In this example, a plastic tube is extruded 13 over the extruder 1 and the tool 2 generated. The tool 2 has a first fluid access 7 over the compressed air by means of a fluid line 8th in the interior of the pipe to the tow plug 9 arrives. At the height of the tow stopper 9 is about the outer contour of the extrudate 13 , here the tube, also a microporous guide element arranged. By applying pressure in the form of compressed air through the first and second fluid access 7 and 14 , an air cushion is created between the surface of the guide member and the wall of the profile. The enlarged illustration clarifies this.

A similar effect will emerge in the next section. The extrudate 13 is via a flexible bellows 10 expanded and over the microporous guide element 11 shaped, again here at the third fluid access 12 Compressed air is introduced around the extrudate 13 a fluid cushion 16 generated.

3 shows this in a sectional view. The compressed air is through the microporous guide element 11 equidistant around the extrudate 13 applied and thus creates an air cushion between the guide element 11 and the outer wall of the extrudate 13 , Via the central fluid access, the compressed air is applied, which continues through the capillary-like micro-openings of the guide element.

Depending on the pressure ratio, the extrudate 13 be so strongly trapped in the area of the tow plug, that the method is suitable for use in the production of stretched O-PVC pipes.

LIST OF REFERENCE NUMBERS

1

extruder

2

Tool

3

calibration Station

4

various follow-up facilities

5

deduction

6

separating device

7

first fluid access

8th

fluid line

9

floating plug

10

flexible bellows

11

second microporous guide element

12

third fluid access

13

extrudate

14

second fluid access

15

first microporous guide element

16

Fluid cushion ring

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102004052972 [0003]
• DE 102008026682 [0004]
• DE 102004052972 A1 [0005]
• DE 102007026309 [0005]

Claims (8)

Method for guiding extrudates ( 13 ) in plastics extrusion in the plastic mass in an extruder ( 1 ), in a tool ( 2 ) and calibrated in one or more cooling stations and final molded, the extrudate ( 13 ) is guided past sliding surfaces in the formed and / or plastically deformable state, characterized in that between the surface of the extrudate ( 13 ) and the sliding surface a fluid cushion ( 16 ), wherein the fluid cushion ( 16 ) is generated by applying pressure by means of fluid and the fluid is applied through the sliding surface, wherein the sliding surface has microporous properties. Process according to Claim 1, characterized in that the pressure is equidistant about the extrudate ( 13 ) is applied through the sliding surfaces, whereby a fluid cushion ring ( 16 ) arises. Method according to one of claims 1 or 2, characterized in that the extrudate ( 13 ) is a plastic profile, preferably a plastic tube. Device for producing a sliding surface for extrudates ( 13 ) in the plastic extrusion the extrudate ( 13 ) leads both in the formed and in the still plastically deformable state, characterized in that the device is a fluid cushion ( 16 ) is producible on the extrudate ( 13 ), wherein the device comprises a guide element which is fluid-permeable to the Fliudpolster ( 16 ) on the guide element. Apparatus according to claim 4, characterized in that the guide element is microporous. Apparatus according to claim 5, characterized in that the microporous guide element is arranged so that the fluid cushion ( 16 ) around the circumference and / or along the outer contour of the extrudate ( 13 ) is producible. Calibration sleeve for guiding and / or forming a plastic strand with a fluid-permeable guide element according to one of claims 4 to 6. Calibration sleeve according to claim 7, characterized in that the calibration sleeve is variable in the passage cross-section.

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