DE102018126192A1 - Method and device for determining and regulating the entry angle of a melt hose into a calibration sleeve - Google Patents

Abstract

The invention relates to a method for determining and regulating the inlet angle (α) of a melt hose (6) into the calibration sleeve (10) of a calibration and cooling unit (8), a calculation unit (31) using the determined values (D1) to determine the target Inlet angle (α_soll) is determined and output to a control unit (30), the control unit (30) controlling a drive unit (26) for moving the calibration and cooling unit (8) in the longitudinal direction in accordance with the desired inlet angle, the drive unit (26) moves to set an actual inlet angle (α_act). The invention also relates to a device for determining and regulating the inlet angle (α) of the melt hose (6) into the calibration sleeve (10) for carrying out the method defined above.

Description

The present invention relates to a method for determining and regulating the entry angle of a melt hose into a calibration sleeve according to claim 1, and a device for determining and regulating the entry angle according to claim 11.

In pipe extrusion lines, a hot, still deformable melt hose emerging from the annular gap nozzle of a pipe head of an extruder runs into a calibration and cooling unit. This has a vacuum tank, at the entrance of which an adjustable calibration sleeve is arranged, in which the pipe to be manufactured is fixed to a desired nominal diameter. After exiting the calibration sleeve, the tube in the vacuum tank is further cooled by sprayed water. Since the pipe is not yet dimensionally stable at this point, it runs after the calibration sleeve over pipe supports arranged in the vacuum tank, so that it passes through a center seal on the outlet side of the vacuum tank. For this purpose, the pipe is pulled from a caterpillar take-off through the vacuum tank and cooling tanks connected to the vacuum tank.

Certain process parameters can be set in the extrusion line to adjust the geometric dimensions of the tube, in particular the outside diameter and a wall thickness. The outer tube diameter is determined by an inner diameter of the calibration sleeve. The wall thickness is determined by a take-off speed set on the caterpillar take-off and a material flow set in the extruder. If a specific geometric dimension is specified for the pipe to be produced, a corresponding recipe can be loaded and activated, for example, depending on which the respective process parameters are set. Such an extrusion line with an exemplary calibration sleeve is shown in DE 10 2005 002 820 B3 described.

In an extrusion line according to the prior art, with an adjustable calibration sleeve and other flexible devices, a dimension change from a first outer diameter to a second outer diameter can take place during the production process. This can be done, for example, by changing from a first recipe to a second recipe. If, for example, only the inside diameter of the calibration sleeve is moved, this results in a change in the inlet angle of the melt hose into the calibration sleeve. As a result of a very small inlet angle or a very large inlet angle, process instabilities can arise which lead to defective pipes and thus to increased rejects as well as to the melt hose being torn off during the extrusion process and thus to the termination of the extrusion process. Inlet angles that are too small lead to inadequate sealing of the melt hose to the calibration sleeve and thus to ventilation of the vacuum tank, which is followed by termination of the extrusion process. Inlet angles that are too large lead to material build-up at the inlet of the calibration sleeve and thus lead to inhomogeneities in the wall thickness and material properties as well as to the melt hose being torn off.

The invention is therefore based on the object of specifying a method and a device with which a simple, reliable and safe manufacturing process is ensured even when there is a change in dimension in the ongoing production of a tube.

This object is achieved by a method according to claim 1 and by a device according to claim 11. The sub-claims describe preferred further developments.

The method according to the invention is particularly advantageous for use in extrusion lines with which a change in dimension can be carried out during production. However, it also offers increased process reliability for extrusion lines that do not allow dimension changes during ongoing production.

With the method according to the invention and with the device according to the invention, the entry angle of a melt hose into the calibration sleeve of a calibration and cooling unit can be determined and regulated to a desired entry angle.

For this purpose, a calculation unit can determine a target entry angle, which can typically be between 3 ° and 20 °, for example 7 °, on the basis of determined values, which are determined, for example, by previously performed simulation calculations or algorithms or which follow from previous experiments. Process parameters that have an influence on the determined inlet angle are, for example, the inside diameter of the calibration sleeve, the geometry of the annular gap nozzle, in particular the diameters, which specify the preliminary inside and outside diameter and thus also the wall thickness of the pipe, the material temperature and the Take-off speed and the material of the tube.

The target entry angle determined by the calculation unit is output to a control unit, which furthermore receives measured values for determining an actual entry angle, which it receives, for example, via a distance or position measuring device that measures the distance between the pipe head and the calibration and cooling unit measures or is obtained from measured values of a drive motor of a drive unit. The control unit forms a difference between the desired entry angle and the actual entry angle and outputs control signals to the drive unit, which is connected to the calibration and cooling unit, in order to adapt the actual entry angle to the desired entry angle. The drive unit, which has a drive motor and suitable drive means, such as. B. a threaded spindle, the calibration and cooling unit can move and thus change the distance between the inlet of the calibration sleeve and the pipe head and thereby adjust the actual inlet angle to the target inlet angle.

The variable to be controlled according to the invention is the inlet angle of the melt hose into the calibration sleeve, but it goes without saying that a preliminary melt hose outer diameter, which is predetermined by the annular gap nozzle, determines the inner pipe diameter of the calibration sleeve, which specifies the final outer pipe diameter, and the distance between the two Entry of the calibration sleeve and the tube head, which results in the entry angle, so that the entry angle does not have to be calculated explicitly for regulating the entry angle. Alternatively, the inventive method can also be operated with the stated distance and with the preliminary tube outer diameter and with the final tube outer diameter. The relationship between the provisional outer tube diameter and the final outer tube diameter and the assignment of a corresponding distance thus corresponds to the determination of an inlet angle.

Preferably, the target inlet angle of the melt hose into the calibration sleeve is already determined and adjusted during the adjustment of the calibration sleeve and thus during the adjustment of the outer tube diameter, so that not only can a safe process and a defective tube be made possible after the outer tube diameter has been changed, but also Process conditions that can lead to the termination of the extrusion process while the calibration sleeve can be avoided.

In particular, it is preferred that the target inlet angle is kept constant during the adjustment of the calibration sleeve, that is to say the distance between the inlet of the calibration sleeve and the pipe head can be directly adapted to the ratio of the preliminary pipe outer diameter to the inner diameter of the calibration sleeve. Alternatively, the target inlet angle can also be set variably if, for. B. during the adjustment of the calibration sleeve further process parameters lead to a changing ideal target entry angle.

In a preferred embodiment, the calculation unit determines a target inlet angle not only as a function of the pipe outer diameter, but also as a function of the final wall thickness of the pipe and / or as a function of the mass gap of the annular gap nozzle, since the provisional and the final wall thickness of the pipe vary can form different geometries or bending lines of the tube between the inlet of the calibration sleeve and the outlet of the annular gap nozzle.

In a preferred embodiment, the target inlet angles determined by the calculation unit can also be based on material parameters, since different materials can differ in terms of their bending line, but also in terms of their flow and adhesion behavior, especially at the inlet of the calibration sleeve.

It is further preferred that the calculation unit takes into account the process temperature, i.e. in particular the material temperature of the melt hose between the pipe head and the inlet of the calibration sleeve, when determining the desired inlet angle, since the process temperature has an influence on the bending line and the adhesive behavior of the melt hose everything at the inlet of the calibration sleeve.

In a preferred embodiment, the actual entry angle is determined by means of an angle measuring device, the measuring method of which is based, for example, on optical or acoustic physical quantities, the measuring method being able to be oriented, for example, axially or radially to the extrusion direction. The measured actual entry angle can be the control unit 31 can be supplied to verify the calculated actual entry angle. This can further increase process reliability, since the actual inlet angle calculated on the basis of the geometries of the annular gap nozzle, the inlet of the calibration sleeve and the distance between the latter two components can deviate from the actual inlet angle due to the flow behavior of the melt hose. In particular, it is preferred that the measured actual entry angle is fed to the control unit in order to be able to regulate the measured actual entry angle.

According to a preferred embodiment, the distance between the pipe head and the calibration sleeve can be determined by means of a distance or position measuring device and fed to the control unit. As a result, the distance between the pipe head and the calibration sleeve can be determined particularly precisely and reliably.

With the device according to the invention, the inlet angle of a melt hose can be in Determine and regulate the calibration sleeve of a calibration and cooling unit using the procedure just described.

• 1 eine schematische Seitenansicht einer Extrusionslinie;
• 2a einen ersten Einlaufwinkel in eine Kalibrierhülse;
• 2b einen zweiten Einlaufwinkel in eine Kalibrierhülse;
• 3 ein Flussdiagramm des erfindungsgemäßen Verfahrens.

The invention is explained in more detail below with reference to the accompanying drawings. Show it:

• 1 a schematic side view of an extrusion line;
• 2a a first entry angle into a calibration sleeve;
• 2 B a second entry angle into a calibration sleeve;
• 3rd a flowchart of the method according to the invention.

The in the 1 Extrusion line shown for the production of pipes 6 comprises an extruder unit 1 with a feed hopper 2nd , an extruder screw 3rd and a pipe head 4th . Via the feed hopper 2nd becomes a thermoplastic 5 in granular or powder form of the extruder unit 1 fed. The granulate or powder is heated, kneaded and plasticized in this. Then the thermoplastic material 5 as a malleable mass through the extruder screw 3rd in the pipe head 4th conveyed and there through an annular gap nozzle 20th that in the 2a and 2 B is shown.

After exiting the annular gap nozzle 20th becomes the hot, still deformable melting hose 6 by means of a caterpillar take-off arranged at the end of the extrusion line 7 through a calibration and cooling unit 8th pulled the a vacuum tank 9 has at the inlet 13 an adjustable, perforated calibration sleeve 10th is arranged. The pipe outside diameter There of the melt hose 6 is before it enters the calibration sleeve 10th initially larger than the inside diameter D1 the calibration sleeve 10th so that the outer wall of the melt hose 6 after entering the calibration sleeve 10th on an inner wall of the calibration sleeve 10th is present. This is supported by the in the calibration and cooling unit 8th prevailing negative pressure of, for example, 500 millibars, through which the melting hose 6 due to the pressure difference between the pipe interior and the calibration and cooling unit 8th against the calibration sleeve 10th is pressed and the pipe 6 the pipe outside diameter There is forced on the inside diameter D1 the calibration sleeve 10th corresponds. An adjustable inlet 13 of the vacuum tank 9 is as a unit with the calibration sleeve 10th executed and moves together with the calibration sleeve 10th .

By the application of the melt hose 6 at the inlet 13 the calibration sleeve 10th becomes the calibration and cooling unit 8th sealed against the atmosphere on the inlet side at the same time, the melting hose 6 is wetted with a liquid to improve the sealing effect. The length of the calibration sleeve 10th is matched to the manufacturing process so that the outer tube diameter There after leaving the calibration sleeve 10th is maintained and by the prevailing negative pressure in the calibration and cooling unit 8th not enlarged.

After leaving the calibration sleeve 10th becomes the pipe 6 through in the vacuum tank 9 arranged pipe supports 12th supported on which the pipe 6 rests with its outer wall. The pipe supports 12th ensure in particular that sagging and deformation of the not yet fully hardened pipe 6 is avoided. The central axis of the pipe 6 becomes the central axis of the calibration sleeve 10th aligned, the pipe supports 12th are depending on the outside diameter of the pipe There proceed in height. If a dimension change is carried out during operation and the pipe outer diameter There the heights of the pipe supports are changed 12th correspondingly step by step to the outer pipe diameter There customized.

The vacuum tank has an outlet 9 a seal 14 on that like the calibration sleeve 10th the calibration and cooling unit 8th seals at the ends, so that in the calibration and cooling unit 8th a negative pressure can be set. The calibration and cooling unit 8th at least one cooling tank is arranged downstream 11 in which the pipe 6 is cooled to about room temperature. The pipe is finally cured 6 instead, which ensures a high dimensional stability of the tube 6 is achieved. The cooling tank 11 the caterpillar take-off is located downstream 7 who is pulling the pipe 6 guaranteed by the extrusion line.

The calibration and cooling unit 8th is by means of a drive unit 26 supported in the longitudinal direction. This is the drive unit 26 with the calibration and cooling unit 8th connected and creates a relative movement between the pipe head 4th and the adjustable inlet 13 . The drive unit 26 has a drive motor 27 on the an electric motor such. B. can be a stepper motor. The drive motor 27 can also be driven hydraulically or pneumatically. The drive motor 27 can be designed in such a way that based on the movement of the drive motor 27 on the relative movement between the calibration and cooling unit 8th and the pipe head 4th can be inferred. The drive motor is used to implement the relative movement 27 with drive means 28 in operative connection, which can be designed as gear wheels, which interact with a fixed rack and generate the relative movement. Alternatively, the drive motor 27 as well as the drive means 28 be stationary and interact with a threaded rod, on the calibration and cooling unit 8th is attached. In a comparable manner, the drive means 28 also have a threaded rod and a nut which produce a relative movement in a manner known to the person skilled in the art.

The calibration and cooling unit 8th furthermore has a position detection which enables the determination of a distance A1 (please refer 2a) , i.e. the distance between the calibration and cooling unit 8th and the pipe head 4th enables. The position detection can be in the drive means 28 be integrated, that is, as already described above, by means of an evaluation of the movement of a stepping motor. Alternatively or additionally, a distance or position measuring device can be used for this 29 be provided, the z. B. the distance by means of ultrasound A1 between the calibration and cooling unit 8th and the pipe head 4th determined. A large number of measuring devices are known to the person skilled in the art which enable position detection by means of optical, electrical or magnetic signals.

To control the drive unit 26 is this as well as the distance or position measuring device 29 with a control unit 30th electrically connected. The control unit 30th received from a calculation unit 31 Target distances or target entry angle α_set that the control unit 30th with the actual distances or actual entry angle α_act which you can get from the distance or position measuring device 29 receives, compares. The drive motor corresponds to the target-actual difference 27 from the control unit 30th controlled and the actual value approximates the target value. The calculation unit 31 calculates the target distances or target entry angle α_set on the basis of its existing process parameters and, if appropriate, on the basis of data that it receives via a user interface 32 with which it is conductively connected. A relevant parameter for determining the target distance or target entry angle α_set is the difference of the inside diameter D2 the nozzle 21 to the inside diameter D1 the calibration sleeve 10th .

In the 2a is the annular gap nozzle 20th that in the pipe head 4th is arranged, shown. The annular gap nozzle 20th has a thorn 22 as well as a nozzle 21 on the thorn 22 surrounds concentrically and thus a mass gap 23 trains. In the 2a gets the thermoplastic 5 from the right, from the extruder screw 3rd driven into the ground gap 23 and thereby gets a tubular geometry. The provisional outer tube diameter There is through the nozzle 21 given the provisional inner diameter of the melt hose Tue from the thorn 22 . This also becomes a preliminary wall thickness M of the melt hose 6 fixed.

The nozzle outlet 21 has a distance A1 to the enema 13 the calibration sleeve 10th on. The inside diameter D1 the calibration sleeve 10th gives the final pipe outside diameter There in front. The final pipe inside diameter Tue results from the outside diameter of the pipe There , that of the extruder unit 1 through the mass gap 23 provided volume flow V and the pipe take-off speed v by the caterpillar trigger 7 is produced.

The inside diameter D2 the nozzle 21 forms with the inner diameter D1 the calibration sleeve 10th and the distance A1 between the nozzle 21 and the enema 13 the calibration sleeve 10th an angle W in which the melt hose 6 essentially in the calibration sleeve 10th runs in relative to the direction of extrusion. As described below, the angle corresponds W essentially an entry angle α of the melt hose 6 , but the angles are not exactly the same. Due to the flow behavior of the melt hose 6 and the resulting bending line of the melt hose 6 , connects the melting hose 6 the exit from the annular gap nozzle 20th with the enema 13 the calibration sleeve 10th not rectilinear, rather a bending radius is formed at the annular gap nozzle 20th and at the inlet 13 the calibration sleeve 10th off, this results in an entry angle α that is not the angle W corresponds.

The inlet angle is for a safe process flow α set in a certain range, with the optimal entry angle α varies depending on parameters.

If the angle is too small α driven, the melting hose seals 6 not reliable to the enema 13 the calibration sleeve 10th so that the vacuum in the calibration and cooling unit 8th is not maintained and as a result of an increase in pressure in the calibration and cooling unit 8th the extrusion process comes to a standstill. If the inlet angles are too large α driven, this leads to material build-up in the inlet 13 the calibration sleeve 10th , this leads to material inhomogeneities, geometrical deviations and also to cracks in the pipe 6 or also to tear off the melt hose 6 , which leads to a standstill in the extrusion process.

2 B shows the same components as that 2a . The 2 B shows the calibration sleeve 10th that have an adjustable calibration sleeve 10th with a smaller inner diameter D1 . The inside diameter D2 the nozzle 21 as well as the mass gap 23 and the distance A1 stay unchanged. This results, in particular, from the unchanged distance A1 that the resulting entry angle α is significantly larger than that in 2a shown. Such an increase in the inlet angle α to prevent the calibration and Cooling unit 8th by means of the drive unit 26 relative to the annular gap nozzle 20th and thus changes the distance A1 .

To determine an actual inlet angle α-ist is on the calibration sleeve 10th an angle measuring device 19th arranged. The calculated actual entry angle α-actual can be verified by the measured actual entry angle α-ist, alternatively the measured actual entry angle α-ist can also be used to regulate the distance A1 the control unit 30th be fed.

According to 3rd a flow chart of the method according to the invention is shown as an example. In an initialization step ST0, the user interface 32 requested a change of dimension, for example by changing from a first recipe R1 to a second recipe R2 . The recipes show, for example, information about the outside diameter of the pipe There , the wall thickness M , the meter weight, the pipe inside diameter Tue and the density of the material used.

When switching from the first recipe R1 to the second recipe R2 the pipe outside diameter There of the pipe 6 changed, there is a conical area of the tube 6 with an outer tube diameter There the one between the pipe outside diameter There of the recipe R1 and the pipe outer diameter There of the recipe R2 lies. The conical area has a transition length LU on.

The recipe R2 is in the calculation unit 31 loaded. In step ST1 the transition length LU of the conical pipe section and the geometry of this pipe section. In step ST2 the temporal courses of the process parameters are determined according to the geometry of the pipe section. First, the size of the mass gap 23 , especially the inside diameter D2 the nozzle 21 , as well as the inside diameter D1 the calibration sleeve 10th and the pull-off speed v certainly. Based on the defined geometry of the conical pipe section, the corresponding distances are as follows A1 as well as the settings of the pipe supports 12th determined. In a third step ST3 the conical pipe section is manufactured, the distance A1 at least depending on the ratio of the inner diameter D2 the nozzle 21 to the inside diameter D1 the calibration sleeve 10th is regulated.

Reference list

1

Extruder unit

2nd

Feed hopper

3rd

Extruder screw

4th

Pipe head

5

Thermoplastic plastic

6

Pipe, melting hose

7

Caterpillar take-off

8th

Calibration and cooling unit

9

Vacuum tank

10th

Calibration sleeve

11

Cooling tank

12th

Pipe supports

13

Adjustable inlet

14

poetry

19th

Angle measuring device

20th

Annular gap nozzle

21

jet

22

mandrel

26

Drive unit

27

Drive motor

28

Drive means

29

Distance or position measuring device

30th

Control unit

31

Calculation unit

32

User interface

A1

Distance (between the inlet of the calibration sleeve 10th and the nozzle outlet 21 )

D1

Inner diameter of the calibration sleeve 10th

D2

Inside diameter of the nozzle 21

There

Pipe outside diameter, melt hose outside diameter

Tue

Inner pipe diameter, inner melt hose diameter

LU

Transition length

M

Wall thickness

R1

recipe 1

R2

recipe 2nd

V

Volume flow

v

Pipe take-off speed

W

angle

α

Entry angle

α_act

is entry angle

α_set

target entry angle

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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.

Patent literature cited

• DE 102005002820 B3 [0003]

Claims (11)

Method for determining and regulating the inlet angle (α) of a melt hose (6) into a calibration sleeve (10) of a calibration and cooling unit (8), a calculation unit (31) using a determined value (D1) to determine a target inlet angle (α_set) is determined and is output to a control unit (30), the control unit (30) controlling a drive unit (26) for moving the calibration and cooling unit (8) in the longitudinal direction in accordance with the desired inlet angle, the drive unit (26) for setting an actual value -Incoming angle (α_act) moves. Procedure according to Claim 1 , characterized in that the target inlet angle (α_soll) of the melt hose (6) into the calibration sleeve (10) is determined and adjusted during the adjustment of the calibration sleeve (10). Procedure according to Claim 2 , characterized in that the target inlet angle (α_soll) of the melt hose (6) into the calibration sleeve (10) is variable or kept constant during the adjustment of the calibration sleeve (10). Method according to one of the preceding claims, characterized in that the calculation unit (31) determines the target entry angle (α_set) based on empirically determined data and / or data determined by simulations and / or by algorithms. Method according to one of the preceding claims, characterized in that the calculation unit (31) calculates a target inlet angle (α_set) as a function of at least one wall thickness (M) and / or a mass gap (23) on the basis of determined values. Method according to one of the preceding claims, characterized in that the calculation unit (31) calculates a target inlet angle (α_set) as a function of a material on the basis of determined values. Method according to one of the preceding claims, characterized in that the calculation unit (31) calculates a target inlet angle (α_set) as a function of a process temperature on the basis of determined values. Method according to one of the preceding claims, characterized in that the control unit (30) is supplied with values determined by means of an angle measuring device (19) in order to verify the actual entry angle (α_actual). Procedure according to Claim 8 , characterized in that the control unit (30) regulates the actual entry angle (α_actual) based on the measured values. Method according to one of the preceding claims, characterized in that the control unit (30) in the longitudinal direction by means of a distance or position measuring device (29) determines a distance (A1) between a pipe head (4) and the calibration sleeve (10). Device for determining and regulating the inlet angle (a), a melt hose (6) into the calibration sleeve (10), a calibration and cooling unit (8), comprising a calculation unit (31) for determining a target inlet angle (α_set) on the basis of determined Values (D1) and output of the target entry angle (α_set), a control unit (30) for receiving the target entry angle (α_set) and for outputting control signals, a drive unit (26) for receiving the control signals and for setting an actual entry angle (α_actual) at least as a function of an adjustable outer tube diameter (Da).

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