METHOD AND DEVICE FOR PRODUCING PLASTIC PROFILES

Abstract

The invention relates to a method for producing plastic profiles, according to which a starting material is plasticated and formed in an extruder, then is cooled and calibrated in at least one dry calibration unit and at least one calibration tank and is subsequently subdivided into individual profile sections. To achieve optimal control of the extrusion line, measurements relating to the geometry and/or the weight of the plastic profile are continuously carried out downstream of the calibration tank and correction values, which are used to change settings in the extruder, the dry calibration unit and/or the calibration tank, are calculated directly from these measured values.

Claims

1. A method for producing plastic profiles comprising the following steps: plasticizing and forming a starting material in an extruder to form a plastic profile; cooling and calibrating the plastic profile in at least one dry calibration unit and at least one calibration tank; and subdividing the plastic profile into individual profile sections; continuously measuring the geometry and/or the weight of the plastic profile downstream of the calibration tank; and calculating directly from the measured values correction values, which are used to change settings in the extruder, the at least one dry calibration unit and/or the at least one calibration tank.

2. The method according to claim 1, characterized in that a measurement consists of the weighing of the profile sections immediately after separation from a profile strand.

3. The method according to claim 1, characterized in that a measurement consists of determining a pull-off force required to convey the plastic profile through a processing line.

4. The method according to claim 1, characterized in that a measurement consists of determining a thickness of at least one wall section of the individual profile sections.

5. The method according to one of claim 1, characterized in that the correction value relates to an extrusion speed.

6. The method according to claim 1, characterized in that a correction value relates to selectively cooling the individual profile sections in a region of an extrusion die.

7. The method according to claim 6, characterized in that cooling of the plastic profile takes place by locally controlled inflation of air at an outlet of the plastic profile from the extrusion die.

8. The method according to claim 1, characterized in that a correction value relates to control of a cooling water flow in individual sections of the at least one dry calibration unit.

9. The method according to claim 8, characterized in that the cooling water flow in individual sections of the at least one dry calibration unit is independently controlled by at least two different circuits.

10. The method according to claim 1, characterized in that a correction value relates to control of a cooling water flow in at least one section of the at least one calibration tank.

11. The method according to claim 10, characterized in that the cooling water flow is independently controlled by at least two different circuits.

12. The method according to claim 1, characterized in that the flow direction of the cooling water in at least one circuit of the at least two different circuits is reversable.

13. The method according to claim 1, further including continuously measuring a position of a calibration table and calculating correction values in order to adjust height, side position and longitudinal position of the calibration table.

14. The method according to claim 13, further including detecting and accounting for obstacles while changing the position of the calibration table by safety systems.

15. A system for producing plastic profiles in an extrusion line, the system comprising: a plurality of tools including at least one dry calibration unit and at least one calibration tank; a calibration table; an extruder; sensors; actuators which alter the setting parameters of the plurality of tools; and a control device communicatively connected to the sensors and the actuators; wherein the plurality of tools are provided downstream of the extruder.

16. The system according to claim 15, characterized in that one of the sensors is a scale, provided downstream of a cutting device, for weighing separated profile sections.

17. The system according to claim 15, characterized in that one of the sensors is adapted to determine the wall thickness in individual regions of the plastic profile.

18. The system according to claim 15, further including at least one die plate arranged at an end face of an extrusion die, the at least one die plate configured and arranged to selectively direct air onto predetermined regions of the plastic profile or an outlet region of the plastic profile at the extrusion line.

19. The system according to claim 15, further including at least one die plate is arranged on an end face of a dry calibration unit, the at least one die plate configured and arranged to selectively direct air onto predetermined regions of the plastic profile or an outlet region of the plastic profile at the extrusion line.

20. The system according to claim 18 , characterized in that the at least one die plate is magnetically attached to the extrusion die.

21. The system according to claim 15, further including a positioning device configured and arranged to adjust the height, side position and longitudinal position of the calibration table.

Description

[0024] In the following, the present invention will be explained in more detail on the basis of the embodiment variants depicted in the figures, wherein:

[0025] FIG. 1 schematically shows an extrusion line according to invention;

[0026] FIG. 2 shows a detail of a calibration table including a dry calibration unit in an oblique view;

[0027] FIG. 3 shows a detail of an extrusion die;

[0028] FIG. 4 shows a front view of a dry calibration unit;

[0029] FIG. 5 shows a front view of an extrusion die;

[0030] FIG. 6 schematically shows a cooling unit installed in the calibration table; and

[0031] FIG. 7 schematically shows the guidance of water in the calibration table and the calibration tools.

[0032] The extrusion line of FIG. 1 consists of an extruder 1 with an extrusion die 1a, a calibration table 2 which is arranged downstream thereof and on which several dry calibration units 3 and several calibration tanks 4 (i.e. the calibration tools) are arranged to cool and calibrate the plastic profile 100 ejected from the extruder 1.

[0033] The calibration tanks 4 can be moved longitudinally on the calibration table 2 to allow quick adaptation to a different number of dry calibration units 3, as it is desirable that the calibration tanks 4 connect directly to the dry calibration units 3.

[0034] Subsequently, the plastic profile 100 is fed into a caterpillar pull-off 5, which provides the necessary tensile forces to pull the plastic profile 100 through the calibration tools. In a measuring station 6, the plastic profile 100 is measured and then cut in a saw 7 into profile sections 101, which are deposited on a tilting table 8.

[0035] The extrusion line is controlled by a control unit 10, which is connected to the individual components of the extrusion line via control lines 11, 12. Schematically, a scale 13 is indicated in the tilting table 8, which determines the weight of each profile section 101 and transmits it to the control unit 10.

[0036] In the same way, the data about the profile geometry and the like are output from the measuring station 6 to the control unit 10. With reference numeral 15, the nature of this data is indicated, namely geometric measurements, color, gloss and scratches. In addition, all relevant data of the other components are transmitted in a way not described here, such as the pull-off force applied by the caterpillar pull-off 5, measured values of pressure and temperature from the calibration tools, etc., and above all identification data with which each tool can be uniquely identified.

[0037] During ongoing operation of the extrusion line, the control unit 10 not only accepts data and issues control commands in order to optimally manage the extrusion process, but also records them in a database in order to gain empirical values for subsequent extrusion processes.

[0038] FIG. 2 shows that the dry calibration units 3a, 3b can easily be mounted on the calibration table 2, since only one mechanical connection via quick-release fasteners 16 has to be established. All connections are provided on the contact surface on the underside of the dry calibration units 3a, 3b, which is not visible here. They interact with connections at the mounting positions of the calibration table 2 that are also not visible here. Therefore, no hoses are required to connect the calibration tools 3a, 3b, 4 to the calibration table 2, which minimizes the risk of mix-ups or errors.

[0039] It is also possible within the scope of the invention to continue to use existing calibration equipment in an extrusion line designed in accordance with the invention. A base plate is firmly attached to the underside of these tools, which has the necessary connections on its underside and connects laterally to other connections via internal connecting lines. These additional connections are then connected via connecting hoses to the typically side-mounted connections of conventional calibration tools. The original tool then forms a unit with the floor plate and the connecting hoses, which is also no longer separated during dismantling and assembly of the tool. For the purposes of the present invention, this unit is regarded as a calibration tool. Again, there is no danger of mix-ups, as there is no further manipulation of the connecting hoses after the initial installation.

[0040] FIG. 3 shows a quick-change system for the extrusion die 1a, which can be folded away sideways. Quick-connect closures combined with preheating of the extrusion die 1a allow an extremely short cycle time of less than 10 minutes when changing the extrusion die 1a.

[0041] FIG. 4 shows the end face of a dry calibration unit 3, wherein the one die plate 18a, 18b is magnetically fixed on both sides of the opening 19, through which the plastic profile 100 passes. Several dies not visible here can be supplied with compressed air via connections 20 in order to selectively cool the plastic profile 100 entering the opening 19. The air volume is measured to create reproducible conditions. In this way, the wall thickness can be individually adjusted to the outer areas of the plastic profile 100, and the weight of the manufactured plastic profile can be precisely regulated (meter weight).

[0042] A similar solution is shown in FIG. 4, in which eight die plates 21a, 21b, 21c, 21d, 21e, 21f, 21g and 21h are mounted magnetically on the face of an extruder die 1a. The die plates 21a and 21e are aimed at visible surfaces of the plastic profile 100, while the die plates 21b, 21c, 21d, 21f and 21h are aimed at extremities, which are always a challenge in extrusion processes.

[0043] FIG. 6 shows a cooling device arranged in calibration table 2, which cools the general cooling water, which is made available to the extrusion line from the outside, to a lower temperature of 5 C. to 8 C., for example. A distributor 23 is supplied via a flow line 24 and a return line 25, which are used to supply special cooling circuits in the calibration tools.

[0044] FIG. 7 shows the general cooling water guidance for the dry calibration units 3a, 3b. The distributor 23 is supplied with general cooling water via a supply line 29 via a water tank 26. In addition, the cooling unit 22 supplies low temperature water as shown above.

[0045] General cooling water at a first pressure level is fed to certain circuits in the dry calibration units 3a, 3b via a first supply line 26a with a small cross-section. A second supply line 26b with a small cross-section leads cooling water of low temperature to further circuits. General cooling water at a further pressure level is supplied via a third supply line 26c with a large cross-section. Return lines 27, 28 return the used cooling water.