CYLINDER FOR A PLASTICS-PROCESSING MACHINE AND METHOD FOR OPERATING AN EXTRUDER

Abstract

A cylinder for a plastics-processing machine is provided, comprising at least two hollow-cylindrical bodies. At least one portion of at least one hollow-cylindrical body is provided with an inner coating, particularly a wear-protection layer, and can be attached to the other hollow-cylindrical body, the one hollow-cylindrical body being attachable to the other hollow-cylindrical body in a plurality of different positions. A device is further provided for processing a material and a method is also provided for operating an extruder.

Claims

1. A cylinder (30) for a plastics-processing machine (38), comprising at least two hollow-cylindrical bodies (10, 32), wherein at least one portion of at least one hollow-cylindrical body (10) is provided with an inner coating (28) comprising a wear-protection layer (28), and can be attached to the other hollow-cylindrical body (32), the one hollow-cylindrical body (10) being attachable to the other hollow-cylindrical body (32) in a plurality of different positions.

2. The cylinder (30) according to claim 1, wherein the one hollow-cylindrical body (10) is attachable to the other hollow-cylindrical body (32) in a position rotated through 180°, 120°, 90° or 45° relative to an original position.

3. The cylinder (30) according to claim 1, wherein the one hollow-cylindrical body (10) is attached to the other hollow-cylindrical body (32) in a detachable manner.

4. The cylinder (30) according to claim 1, wherein the hollow-cylindrical bodies (10, 32) are screwed to one another.

5. The cylinder (30) according to claim 1, wherein the hollow-cylindrical bodies (10, 32) have respectively at least two longitudinal bores (24) parallel to one another, which overlap one another forming a spectacle bore (24).

6. The cylinder (30) according to claim 5, wherein the inner coating (28) is formed substantially in the interstice region of the spectacle bore (24).

7. The cylinder (30) according to claim 1, wherein the inner coating (28) is formed over the entire inner surface (26) of the hollow-cylindrical body (10) or in a region of an angle plane of approximately 45° to an axial plane of the cylinder (10).

8. The cylinder (30) according to claim 1, wherein the other hollow-cylindrical body (32) is provided at least in one portion with an inner coating (28) comprising a wear-protection layer (28).

9. The cylinder (30) according to claim 6, wherein the inner coating (28) of the one hollow-cylindrical body (10) is different from the inner coatings (28) of the other hollow-cylindrical body (32).

10. The cylinder (30) according claim 1, wherein the inner coating (28) has an alloy, comprising at least one of a metal alloy, ceramic and/or bimetal, or a combination thereof.

11. The cylinder (30) according to claim 1, wherein the inner coating (28) is produced by inductive hardening.

12. A device (38) for processing a material, for example plastic, rubber or suchlike, with a multi-screw extruder (38), comprising a double-screw extruder (38), wherein the extruder (38) has at least two screws (40) for the processing of the material, wherein the screws (40) are mounted rotatably in a cylinder (30) according to claim 1 and are drivable by means of at least one drive.

13. The device (38) according to claim 12, wherein the screws (40) at least in one portion have an outer coating, comprising a wear-protection layer.

14. The device (38) according to claim 13, wherein the outer coating is provided on the screws (40) in the region of the inner coating of the cylinder (30) or respectively of the hollow cylindrical body (10), wherein the outer coating is formed as a wear-protection layer suited to the inner coating.

15. The device (38) according to claim 13, wherein the outer coating of the screws (40) has an alloy, comprising at least one of a metal alloy, ceramic, molybdenum and/or bimetal, or a combination thereof.

16. The device (38) according to claim 12, wherein the multi-screw extruder (38) is configured as an extruder (38) rotating in the opposite direction or in the same direction.

17. The device (38) according to claim 12, wherein the drive comprises a motor which is operable in two rotation directions.

18. A method for operating an extruder (38), with at least two screws (40), comprising the device (38) according to claim 12, wherein the processing of the material is stopped and a hollow-cylindrical body (10) of the extruder cylinder (30) is attached in a different position relative to its original position.

Description

[0026] Various possibilities now exist for configuring and further developing the teaching of the present invention in an advantageous manner. For this, on the one hand, reference is to be made to the claims and on the other hand to the following explanation of a preferred example embodiment of the cylinder according to the invention for a plastics-processing machine and of the device for processing a material, with the aid of the drawings. In connection with the explanation of the preferred example embodiment of the cylinder according to the invention, the device and the method according to the invention for operating an extruder, with the aid of the drawings, also in general preferred configurations and further developments of the teaching are explained. Further aspects, features and advantages of the cylinder disclosed here and device will also emerge from the example embodiments explained below and from the figures. There are shown:

[0027] FIG. 1 in a side view, partly in section, an example embodiment of a hollow-cylindrical body with an inner coating;

[0028] FIG. 2 in a side view, partly in section, an example embodiment of a cylinder, divided in two, with the hollow-cylindrical body according to FIG. 1 and with a further hollow-cylindrical body;

[0029] FIG. 3a in a diagrammatic illustration in section, an example embodiment of a device for processing a material with the cylinder according to FIG. 2; and

[0030] FIG. 3b in a diagrammatic illustration in section, the device for processing a material according to FIG. 3a, wherein the hollow-cylindrical body according to FIG. 1 was attached at a different position.

[0031] In the following, the example embodiments are explained by way of example. Conforming or comparable elements are given the same reference numbers.

[0032] In FIG. 1 an example embodiment of a hollow-cylindrical body 10 is illustrated in a side view, partly in section. The hollow-cylindrical body 10 has a longitudinal axis 12. The longitudinal axis 12 constitutes a rotation axis of the hollow-cylindrical body 10. The longitudinal axis 12 extends in the method direction of the hollow-cylindrical body 19. Along its longitudinal axis, the hollow-cylindrical body 10 has two ends 14. The ends 14 of the hollow-cylindrical body 10 thus form opposite lateral faces.

[0033] At each end 14 the hollow-cylindrical body 12 has a projection 16 extending substantially in perpendicular direction to the longitudinal axis 12 of the hollow-cylindrical body 10. In the present example embodiment, the projection 16 is configured as a flange 16. The flange 16 is formed in one piece with the hollow-cylindrical body 10 and therefore forms a flange portion 16 of the hollow-cylindrical body 10. The flange portion 16 can have a round cross-section, but preferably, as in the present example embodiment, can also have a rectangular cross-section. The cross-section of the flange 16 extends in a plane which runs substantially perpendicularly or transversely to the longitudinal axis 12 of the hollow-cylindrical body 10. The cross-sections of the two flange portions can be identical or, as in the present example embodiment, can have a cross-sectional area of different size. The flange portion or respectively flange 16 has one or more bores 18. The bores 18 can be embodied as through-bores or blind bores. The bores 18 of the flange 16 can, as in the present example embodiment, have an internal thread. The bores 18 can therefore be configured as threaded bores 18. By means of these threaded bores 18, the hollow-cylindrical body 10 can be attached to another hollow-cylindrical body and can preferably be screwed to the latter by means of bolts or pins (shown in FIG. 2). In addition, the flange portion 16 can have openings 20, for example in the shape of a hexagon. Other shapes, such as for instance triangle, rectangle and round are also conceivable. The openings 20 can also be configured as a bore. The openings 20 can be arranged only on one of the two flange portions 16 (on the right-hand flange portion in FIG. 1) or on both flange portions 16 (not shown in FIG. 1). Furthermore, the flange portions 16 can have, additionally or alternatively, bores 22, preferably blind bores 22. These blind bores 22 can likewise be arranged only on one of the two flange portions 16 (on the left-hand flange portion in FIG. 1) or on both flange portions 16 (not shown in FIG. 1). The two flange portions 16 can therefore be configured similarly or identically. The bores 18, openings 20 and/or the blind bores 22 extend substantially in a direction parallel to the longitudinal axis 12 of the hollow-cylindrical body 10.

[0034] The hollow-cylindrical body 10 has two longitudinal bores 24 parallel to one another, which extend substantially in the direction of the longitudinal axis 12 of the hollow-cylindrical body 10. In the present example embodiment, the longitudinal bores 24 overlap one another and form a spectacle bore 24 (illustrated diagrammatically in FIGS. 3a and 3b). The spectacle bore defines an inner surface 26 of the hollow-cylindrical body 10. Alternatively, the hollow-cylindrical body 10, depending on the application, can have only one longitudinal bore 24 or several, for example three, four or five longitudinal bores 24, wherein in the latter case the longitudinal bores 24 can overlap one another at least in pairs.

[0035] As shown in FIG. 1, the hollow-cylindrical body 10 has, at least in one portion, an inner coating 28. In the present example embodiment, the inner coating 28 is formed over the entire inner surface 26 of the hollow-cylindrical body 10. Alternatively, the inner coating 28 can be formed only in portions on the inner surface 26 of the hollow-cylindrical body 10. For example, the inner coating 28 is formed substantially in the interstice region of the spectacle bore 24 of the hollow-cylindrical body 10. The inner coating 28 is, in particular, a wear-protection layer 28. The wear-protection layer 28 is preferably made from a wear-inhibiting material. The wear-protection layer 28 can have for example an alloy, preferably a metal alloy, ceramic, and/or bimetal, preferably tungsten carbide, or a combination thereof. Alternatively or additionally, the wear-protection layer 28 can be produced by hardening, for example inductive hardening. In the present example embodiment, the wear-protection layer 28 is formed from tungsten carbide.

[0036] FIG. 2 shows now in a side view, partly in section, an example embodiment of a cylinder 30, divided in two, with the hollow-cylindrical body 10 according to FIG. 1 and with a further hollow-cylindrical body 32. However, several, e.g. three, four, five, etc. hollow-cylindrical bodies 10 and/or hollow-cylindrical bodies 32 can also form a cylinder 20.

[0037] The hollow-cylindrical body 32 corresponds substantially to the hollow-cylindrical body 10. The hollow-cylindrical body 32 therefore has substantially the features described with reference to the hollow-cylindrical body 10 and shown in FIG. 1. A difference between the hollow-cylindrical body 32 and the hollow-cylindrical body 10 lies, however, in that in the present example embodiment the hollow-cylindrical body 32 has no inner coating 28. Alternatively, the hollow-cylindrical body 32 can have at least in one portion an inner coating 28, preferably on the inner surface 26 of its longitudinal bore(s) 24. In a variant, the hollow-cylindrical body 32 can have on its entire inner surface 26 an inner coating in the form of a wear-protection layer 28. The inner coating 28 of the hollow-cylindrical body 10 can be different from the inner coating 28 of the hollow-cylindrical body 32. The inner coating 28 can therefore be adapted to the respective method zone of the cylinder 30. Alternatively, however, the inner coating 28 can be embodied identically in the hollow cylindrical body 10, 32.

[0038] The hollow-cylindrical body 10 is attached to the other hollow-cylindrical body 32, wherein the hollow-cylindrical body 10 is attachable to the other hollow-cylindrical body 32 in several different positions. For this purpose, in the present example embodiment, the hollow-cylindrical body 10 is attached to the other hollow-cylindrical body 32 in a detachable manner. As shown in FIG. 2, the two hollow-cylindrical bodies 10 and 32 are screwed to one another by means of bolts 34. Alternatively or additionally, the hollow-cylindrical bodies 10, 32 can be connected to one another by means of pins, threaded rods, lock screws, etc. In FIG. 2 this is illustrated by way of example by threaded pins 36. The hollow-cylindrical bodies 10, 32 are attached to one another by means of their flange portions 16. Here, they are connected to one another so that the spectacle bore 24 of the hollow-cylindrical body 10 with the spectacle bore 24 of the hollow-cylindrical body 32 are aligned congruently in longitudinal direction along the longitudinal axis 12. The longitudinal axes of the spectacle bores 24 are therefore formed congruently to one another.

[0039] As shown in FIG. 2, owing to the divided configuration of the cylinder 30, the hollow-cylindrical body 10 can be dismantled again. In particular in the case of wear, the hollow-cylindrical body 10 can be detached from the hollow-cylindrical body 32 again by means of the bolts and pins 36. The hollow-cylindrical body 10 is therefore able to be attached to the other hollow-cylindrical body 32 in a position rotated through for example 180°, 120°, 90° or 45° relative to its original position (i.e. to its originally mounted position). The hollow-cylindrical body 10 can be rotated about its longitudinal axis 12 and subsequently attached to the other hollow-cylindrical body 32 again. Alternatively or additionally, the hollow-cylindrical body 10 can also be rotated about an axis perpendicular to the longitudinal axis 12. This perpendicular axis preferably lies in the horizontal plane of the hollow-cylindrical body 10. A rotation of the hollow-cylindrical body 10 through 180° about the longitudinal axis 12 and/or about the axis of the hollow-cylindrical body 10 perpendicular to the longitudinal axis 12 is preferred. Alternatively or additionally, the hollow-cylindrical body can be configured to be rotatable/revolvable about an axis of the cylinder 30 by any and/or required angle depending on the configuration of the cylinder 30 and/or of an extruder. The hollow-cylindrical body 10 can therefore be mounted in two or more positions on another hollow-cylindrical body.

[0040] In FIGS. 3a and 3b an example embodiment is illustrated, in a diagrammatic illustration in section, of a device 38 for processing a material, in this case plastic, with the cylinder 30 according to FIG. 2. The device comprises an extruder, wherein the extruder is configured as a multi-screw extruder. In the present example embodiment, the extruder is a double-screw extruder. The extruder has two screws 40 for the plasticizing of plastic. The screws are mounted rotatably in the cylinder 30. As can be seen in FIGS. 3a and 3b, the screws are mounted in the spectacle bore 24 of the cylinder 30.

[0041] The screws 40 can have at least in one portion an outer coating, in particular a wear-protection layer. The outer coating on the screws 40 can be provided in the region of the inner coating 28 of the cylinder 30 or respectively of the hollow-cylindrical body 10. This means that the outer coating can be provided on the screws 40 in the region at which the region of the inner coating 28 of the cylinder 30 or respectively of the hollow-cylindrical body 10 is provided opposite the screw 40. In a variant, the outer coating can be configured as a suitable or corresponding wear-protection layer to the inner coating 28 of the cylinder 30. The outer coating of the screws 40 can have an alloy, preferably metal alloy, ceramic, molybdenum and/or bimetal, preferably tungsten carbide or any combination thereof. In a variant, the screws 40 can have one or more outer coatings. For example, the screws can have two outer coatings. These two outer coatings can be, for example, molybdenum and tungsten carbide. In the present example embodiment, the screws 40 have an outer coating which extends over the portion of the screw which is situated within the hollow-cylindrical body 10, wherein the outer coating is configured as a suitable wear-protection layer with respect the inner coating 28 of the hollow-cylindrical body 10 and has tungsten carbide.

[0042] The screws 40 are drivable by means of a drive which is not illustrated. The drive comprises a motor which is operable in two rotation directions. In addition, the drive can comprise a gear and/or transmission elements in the form of coupling elements. The extruder can be configured as an extruder rotating in the same direction or in the opposite direction. In the present example embodiment, the extruder is configured as a meshing (here closely meshing) double-screw extruder rotating in the opposite direction (indicated by the arrows in FIGS. 3a and 3b). The drive drives the first screw 40 (the left-hand screw in FIGS. 3a and 3b) anti-clockwise, and the second screw 40 (the right-hand screw in FIGS. 3a and 3b) clockwise. However, a converse rotation direction of the screws is also conceivable.

[0043] In FIG. 3a the rotation direction of the individual screws 40 and the acting contact pressure forces F are shown. In operation, the screws 40 act on the cylinder and therefore on the hollow-cylindrical body 10. Wear occurs in particular on the hollow-cylindrical body 10 in the region of approximately 9.00 to 11.00 hrs and 13.00 to 15.00 hrs; illustrated diagrammatically by the thickened circular arcs 42. The cylinder wear occurs, as shown in FIG. 3a, on the wear-protection layer 28. Therefore, the hollow-cylindrical body 10 is not damaged directly. Depending on the plastics material which is processed, the processing is stopped after a particular operating duration, at which the occurring cylinder wear 42 is still so small that it still does not lead to any substantial damage to the product, the cylinder 30 and/or the screws 40. This is usually the case when only the wear-protection layer 28 of the hollow-cylindrical body 10 is affected by wear. When this operating point is reached, the hollow-cylindrical body 10 of the extruder cylinder 30 is attached in a different position relative to its original position. In the present example embodiment, the hollow-cylindrical body 10 is firstly detached from the hollow-cylindrical body 32 by means of the bolts 34. The hollow-cylindrical body 10 is then rotated through 180° about its longitudinal axis 12. Thus the hollow-cylindrical body 10 is attached or respectively screwed in this position onto the hollow-cylindrical body 32 again. The hollow-cylindrical body 10 was therefore attached to the other hollow-cylindrical body 32 from its original position (as shown in FIG. 3a) in a different position (here rotated through 180°) (as shown in FIG. 3b).

[0044] FIG. 3b now shows the hollow-cylindrical body 10 in a position, rotated through 180° about the longitudinal axis 12 and screwed on the other hollow-cylindrical body 32 again. The cylinder wear 42 which is present therefore now lies in the region of approximately 7.00 to 9.00 hrs and 15.00 to 17.00 hrs. When the processing of plastics material is now started again, the cylinder wear now takes place on the wear-protection layer 28 which is not wearing or is scarcely affected, in the upper region of the hollow-cylindrical body 10 or respectively again for instance in the 9.00 hrs to 11.00 hrs and 13.00 to 15.00 hrs region.

[0045] With regard to further details, to avoid repetitions, reference is to be made to the general description.

[0046] Finally, it is to be expressly pointed out that the example embodiment or respectively example embodiments described above serves only for the explanation of the claimed teaching, but does not restrict this to the example embodiment.

REFERENCE LIST

[0047] 10 hollow-cylindrical body with coating [0048] 12 longitudinal axis [0049] 14 end [0050] 16 flange portion [0051] 18 threaded bores [0052] 20 openings [0053] 22 blind bores [0054] 24 longitudinal bores/spectacle bore [0055] 26 inner surface [0056] 28 inner coating/wear-protection layer [0057] 30 cylinder [0058] 32 hollow-cylindrical body without coating [0059] 34 bolts [0060] 36 threaded pins [0061] 38 device/extruder [0062] 40 screw(s) [0063] 42 cylinder wear [0064] F contact pressure forces