METHOD FOR PRODUCING PLASTIC PRODUCTS BY MEANS OF AN EXTRUDER, AND SHAPING SYSTEM

Abstract

The invention relates to a process for the production of articles, exemplarily a plastic article, by means of an extruder (1) to which a first plastic composition of a first main component and at least one associated minor component is supplied from a first group of dosing stations (21, 24). According to the invention, during the production time of a first production order there is prepared a second group of dosing stations (31, 33) at the extruder for a second production order for which a second plastic composition of a second main component and at least one associated minor component that is different from the first plastic composition has to be supplied to the extruder. After completion of the first production order it is reset to the second production order by terminating the supply of the first plastic composition by closing a first shut-off device (8) and starting the supply of the second plastic composition by opening a second shut-off device (8′).

Claims

1.-15. (canceled)

16. A process for the production of plastic articles in a plant having two groups of dosing stations for the extruder (1) and a control for the groups of dosing stations, wherein by means of an extruder (1), to which a first plastic composition of a first component and at least one associated minor component is supplied from a first group of dosing stations (21, 22, 23, 24, 25, 26), wherein during the production time of a first production order a second group of dosing stations (31, 32, 33, 34) at the extruder (1) is prepared for a second production order for which a second plastic composition of a second main component and at least one associated minor component that is different from the first plastic composition has to be supplied to the extruder (1) and that after completion of the first production order it is reset to the second production order by terminating the supply of the first plastic composition and starting the supply of the second plastic composition, characterized in that the supply of the first plastic composition is terminated by closing a first shut-off device (8) and the supply of the second plastic composition is started by opening a second shut-off device (8′), wherein closing the first shut-off device (8) and opening the second shut-off device (8′) are performed at the same time or in a short interval.

17. The process according to claim 16, characterized in that during the production time of the first production order the second group of dosing stations (31, 32, 33, 34) is shifted inactive, so that the dosing stations (31, 32, 33, 34) of the second group can be prepared manually and/or by means of a second control.

18. The process according to claim 16, characterized in that the switching is done by manually switching a part of the groups of dosing stations.

19. The process according to claim 16, characterized in that each shut-off device (8, 8′) is a shut-off gate in a common supply line (4, 4′) from the first (21, 22, 23, 24, 25, 26) or second (31, 32, 33, 34) group of dosing stations to the extruder.

20. The process according to claim 16, characterized in that the closing or opening positions of the shut-off gates (8, 8′) are detected by means of limit switches or RFID chips and are transferred by means of a machine control.

21. The process according to claim 16, characterized in that the process is carried out by means of several extruders (1) to each of which a first and a second group of dosing stations belong.

22. The process according to claim 16, characterized in that the one or all extruder(s) (1) have more than two groups of dosing stations from which subsequently different plastic compositions are supplied.

23. The process according to claim 16, characterized in that at least the two main components and/or at least one or all of the minor components are free-flowing.

24. The process according to claim 16, characterized in that the articles are plastic articles, especially blown films, cast films, non-wovens, or injection-molded parts.

25. A plastic shaping plant having at least one extruder (1), wherein the plant has two groups of dosing stations for the extruder (1) and a control for the groups of dosing stations, characterized in that the plant and the control are configured to perform the process according to any of the preceding claims, wherein closing the first shut-off device (8) terminates the supply of the first plastic composition and wherein opening the second shut-off device (8′) starts the supply of the second plastic composition, wherein closing the first shut-off device (8) and opening a second shut-off device (8′) can be performed at the same time or in a short interval.

26. The plant according to claim 25, wherein a gravimetric screw dosing system is provided that is configured to dose the main component by means of a dosing screw and to supply the minor component.

27. The plant according to claim 25, wherein a batch dosing system is provided.

28. The plant according to claim 25, wherein a vibrator dosing system is provided.

29. The plant according to claim 25, characterized in that the plastic shaping plant is a blown film plant, cast film plant, spunbonded fabric plant, blow molding plant, or injection-molding plant.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 shows a schematic side view of a blow molding plant; and FIG. 2 shows a schematic plan view of the blow molding plant of FIG. 1.

DETAILED DESCRIPTION OF EXAMPLES

[0035] The blow molding plant shown in the figures contains an extruder 1 that can selectively be supplied by two dosages 2 and 3 with one of two different mixtures of plastic granules.

[0036] The first dosage 2 comprises a group of six dosing stations to which a dosing station 21 for a main component of a first mixture of plastic granules belongs that is arranged above the extruder 1 and is connected thereto by a downpipe 4.

[0037] Horizontal connecting pipes 5 laterally lead to the downpipe 4. In said connecting pipes 5 conveying screws 6 are arranged that—driven by drives 7—convey up to five minor components of the first mixture of plastic granules from five dosing stations 22, 23, 24, 25, and 26 for the minor components into the downpipe 4. The dosing stations 22, 23, 24, 25, and 26 for the minor components are arranged in a semicircle around dosing station 21 for the main component.

[0038] The second dosage 3 comprises a group of four dosing stations to which a dosing station 31 for a main component of a second mixture of plastic granules belongs that is arranged above the extruder 1 and is connected thereto by a downpipe 4′.

[0039] Horizontal connecting pipes 5′ laterally lead to the downpipe 4′. In said connecting pipes 5′ conveying screws 6′ are arranged that—driven by drives 7′—convey up to three minor components of the second mixture of plastic granules from three dosing stations 32, 33, and 34 for the minor components into the downpipe 4′. The dosing stations 32, 33, and 34 for the minor components are arranged in a semicircle opposite to the dosing stations 22, 23, 24, 25, and 26 of the first dosage 2 around the dosing station 31 for the main component of the second dosage 3.

[0040] Below the mixing points of the respective main and minor components in the downpipes 4 and 4′ there is a schematically drawn in shut-off gate 8, 8′ each that can be opened and closed by a respective drive 9, 9′. The positions of the shut-off gates 8, 8′ can be controlled by means of limit switches or RFID chips that are connected to a machine control. The shut-off gates 8, 8′ may be opened and closed by a program or by manual input at the machine control.

[0041] Assuming there is just running a first production order in which the extruder 1 receives the first mixture of plastic granules from the first dosage 2, wherein the shut-off gate 8 is open and the shut-off gate 8′ is closed.

[0042] During the production time of the first production order the dosing stations 31, 32, 33, and 34 of the second dosage 3 can be prepared for a second production order that can immediately start after the completion of the first production order. For that, the shut-off gate 8 is closed and the shut-off gate 8′ is opened, so that the extruder 1 now receives the second mixture of plastic granules from the second dosage 3.

LIST OF REFERENCE NUMBERS USED

[0043] 1 extruder

[0044] 2 first dosage

[0045] 3 second dosage

[0046] 4, 4′ downpipe

[0047] 5, 5′ connecting pipe

[0048] 6, 6′ conveying screw

[0049] 7, 7′ conveying screw drive

[0050] 8, 8′ shut-off gate

[0051] 9, 9′ shut-off gate drive

[0052] 21, 31 dosing station for main component

[0053] 22, 32 dosing station for minor component

[0054] 23, 33 dosing station for minor component

[0055] 24, 34 dosing station for minor component

[0056] 25 dosing station for minor component

[0057] 26 dosing station for minor component