PLASTICIZING CYLINDER OF A PLASTIC EXTRUDER OR AN INJECTION MOLDING MACHINE

Abstract

A barrel of a plastics extruder or a plasticizing cylinder of an injection-molding machine includes the barrel or cylinder having a wall, at least one spiral recess formed in the wall, and at least one heating element arranged in one spiral recess. The barrel or cylinder has at least one cooling element arranged in another spiral recess and the spiral recesses extend parallel to one another along the surface of the barrel or cylinder. Also, the cooling element is formed as a tube and the tube is or can have a liquid cooling medium flowing therethrough.

Claims

1. A plasticizing cylinder of a plastic extruder or an injection molding machine, the plasticizing cylinder comprising: a wall with at least one first recess and at least one second recess formed in the wall, wherein the at least one first recess and the at least one second recess are spiral shaped and extend parallel to one another along an outer surface of the wall; and at least one heating element arranged in the at least one first recess and at least one cooling element arranged in the at least one second recess, wherein the cooling element is a tube configured for a liquid cooling medium to flow therethrough.

2. The plasticizing cylinder according to claim 1, wherein the tube is pressed into the at least one second recess.

3. The plasticizing cylinder according to claim 1, wherein a plurality of heating elements are arranged in the at least one first recess and a plurality of cooling elements are arranged in the at least one second recess, the wall comprises a plurality of axially adjacent zones, wherein in each of the plurality of axially adjacent zones at least one heating element or at least one cooling element is arranged, and the plurality of heating elements and the plurality of cooling elements are separately controlled zone by zone.

4. The plasticizing cylinder according to claim 3, wherein in at least one of the plurality of axially adjacent zones both a cooling element and a heating element are arranged and in at least one adjacent zone to the at least one of the plurality of axially adjacent zones at least one heating element is arranged but a cooling element is not arranged.

5. The plasticizing cylinder according to claim 1, wherein the cooling elements is shaped to fit a cross-section of the at least one second recess and the heating element is shaped to fit a cross-section of the at least one first recess, wherein the heating element is in contact with a bottom and sidewalls of the at least one first recess.

6. The plasticizing cylinder according to one claim 1, wherein the at least one first recess and the at least one second recess have a rectangular cross-section.

7. The plasticizing cylinder according to claim 6, wherein the heating element has a rectangular cross-section shaped to fit the at least one first recess.

8. The plasticizing cylinder according to claim 6, wherein the cooling element has a round cross-section.

9. The plasticizing cylinder according to claim 1, wherein the at least one first recess and the at least one second recess are milled into the wall.

10. The plasticizing cylinder according to claim 1, wherein the heating element is provided as a heating cartridge, the heating cartridge being an electric resistance heating cartridge.

11. The plasticizing cylinder according to claim 1, wherein at least one insulating sleeve is arranged on the outside of the wall, the at least one insulating sleeve being arranged around the at least one cooling element and the at least one heating element.

12. A plasticizing cylinder with a wall, at least one first recess and at least one second recess being formed in said wall, wherein the at least one first recess and the at least one second recess are spiral-shaped and extend parallel to one another along an outer surface of the wall, at least one heating element being arranged in the at least one first recess and at least one cooling element being arranged in the at least one second recess, wherein the cooling element is a tube configured for a liquid cooling medium to flow therethrough, wherein the at least one first recess and the at least one second recess have a rectangular cross-section, and wherein the at least one heating element has a rectangular cross-section shaped to fit the at least one first recess.

13. The plasticizing cylinder according to claim 12, wherein a plurality of heating elements are arranged in the at least one first recess and a plurality of cooling elements are arranged in the at least one second recess, the wall comprises a plurality of axially adjacent zones, wherein in each of the plurality of axially adjacent zones at least one heating element or at least one cooling element is arranged, and the plurality heating elements and the plurality cooling elements are separately controlled zone by zone.

14. The plasticizing cylinder according to claim 13, wherein in at least one of the plurality of axially adjacent zones both a cooling element and a heating element are arranged and in at least one adjacent zone to the at least one of the plurality of axially adjacent zones at least one heating element is arranged but a cooling element is not arranged.

15. The plasticizing cylinder according to claim 12, wherein the at least one first recess and the at least one second recess are milled into the wall.

16. The plasticizing cylinder according to claim 12, wherein the at least one heating element is provided as at least one heating cartridge and the at least one heating cartridge is at least one electric resistance heating cartridge.

17. The plasticizing cylinder according to claim 12 further comprising at least one insulating sleeve arranged on the outside of the wall around the at least one cooling element and the at least one heating element.

18. A plasticizing cylinder with a wall, at least one first recess and at least one second recess being formed in said wall, wherein the at least one first recess and the at least one second recess are spiral-shaped and extend parallel to one another along an outer surface of the wall, at least one heating element being arranged in the at least one first recess and at least on cooling element being arranged in the at least one second recess, wherein the cooling element is a tube configured for a liquid cooling medium to flow therethrough, wherein a plurality of heating elements are arranged in the at least one first recess and a plurality of cooling elements are arranged in the at least one second recess, the wall comprises a plurality of axially adjacent zones, wherein in at least one of the plurality of axially adjacent zones a cooling element and a heating element are arranged, and wherein in at least one adjacent zone to the at least one of the plurality of axially adjacent with the cooling element and the heating element arranged therein at least one heating element is arranged and a cooling element is not arranged.

19. The plasticizing cylinder according to claim 18, wherein the at least one first recess and the at least one second recess are milled into the wall, and the at least one heating element is at least one electric resistance heating cartridge.

20. The plasticizing cylinder according to claim 18 further comprising at least one insulating sleeve arranged on the outside of the wall around the at least one cooling element and the at least one heating element.

Description

DRAWINGS

[0034] In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

[0035] FIG. 1 shows in a schematic, perspective view a plasticizing cylinder;

[0036] FIG. 2 shows in a schematic longitudinal sectional view the plasticizing cylinder in FIG. 1; and

[0037] FIG. 3 shows in a schematic longitudinal sectional view of the plasticizing cylinder in FIG. 2 with additional insulating sleeves.

[0038] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

[0039] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0040] Referring to FIGS. 1, 2 and 3, a plasticizing cylinder 1 is shown. The plasticizing cylinder 1 has a hollow cylindrical configuration and an internal space 2 defined by the plasticizing cylinder 1 where a screw of an extruder is arranged. Non-limiting examples of an extruder include a single screw extruder, a plastic extruder, a twin screw extruder, a degassing extruder, a screw with constant or conical diameter, among others. In the illustrated implementation the internal space 2 is hollow cylindrical. The plasticizing cylinder 1 comprises a wall 3, which delimits the internal space 2.

[0041] As shown in FIGS. 1-3, a number of spiral-shaped recesses 4, 5 are arranged on an outer surface of the wall 3. In particular, two spiral-shaped recesses 4, 5 are formed on the outer (+/z direction) surface of the wall 3. The two recesses 4, 5 run parallel to each other, so that in the longitudinal sectional view according to FIG. 2, the first recess 4 and the second recess 5 are arranged adjacent to each other in the longitudinal direction (x direction). In some variations the first recess 4 is located exactly in the middle between two adjacent second recesses 5, so that the distance between the recesses 4, 5 is constant.

[0042] In the first recess 4 there is arranged at least one cooling element 6 and in the second recess 5 at least one heating element 7. It is conceivable to arrange more than one heating element 7 and/or more than one cooling element each distributed in different zones in order to further improve the temperature control. Accordingly, an energy-efficient plasticizing system for extruders is provided and waste heat losses are reduced. This also significantly reduces the heating energy requirement, i.e., the heating energy need to desirably heat the plasticizing cylinder 1. This is achieved by the fact that plasticizing cylinder 1 has at least two spiral-shaped recesses 4, 5 on its surface.

[0043] In some variations, the recesses 4, 5 have a rectangular cross-section. The heating elements 7 have a rectangular cross-section adapted to the recesses 5. The heating elements 7 are provided as heating cartridges with a rectangular, e.g., square cross-section, wherein the heating cartridges 7 each have an electrical resistance heating element (not shown) and provide electrical resistance heating.

[0044] In at least one variation, the cooling element 6 is a copper tube pressed into the recess 4. It is conceivable that several cartridge heaters can be embedded per heating zone (not labeled) along the longitudinal direction (x direction) of the plasticizing cylinder 1. The energy efficiency of controlling the temperature of the plasticizing cylinder 1 is improved, since the embedded heating elements 7 can emit heat to the plasticizing cylinder 1, especially via of their surface. That is, three sides of the four-sided heating elements 7 are in contact with the plasticizing cylinder 1 and thereby three sides % of the four-side heating elements provide or emit heat to the plasticizing cylinder 1. Accordingly, it should be understood that the cross-section of the heating elements 7 is adapted to the cross-section of the recess 5.

[0045] In some variations, the cross-section of the cooling elements 6 is also adapted to the cross-section of the recess 4. The cooling tubes embedded parallel to the heating elements 7 effectively dissipate excess heat via a liquid medium (not labeled) flowing through the cooling elements 6. The liquid medium can be water or oil, among others.

[0046] The plasticizing cylinder 1 has a plurality of axially adjacent zones (e.g., a plurality of axially adjacent heat zones), wherein at least one heating element 7 and/or at least one cooling element 6 is arranged in each zone, and wherein the heating elements 7 and/or the cooling elements 6 can be controlled and/or closed loop controlled separately for each zone. As shown in FIG. 1, there are four zones A-D, each with one heating element 7 and one cooling element 6.

[0047] If an overtemperature occurs, cooling liquid medium is controlled by an upstream valve (not shown). This system is significantly more efficient than the more inert air cooling used currently. By integrating the cooling elements 6 and the heating elements 7 into the plasticizing cylinder 1, it is possible to react considerably faster, i.e., within a shorter time frame, to external influences.

[0048] Another advantage of this system is that the plasticizing cylinder 1 can be insulated by means of multiple insulation sleeves 8 a shown in FIG. 3. In some variations, there is one insulation sleeve 8 per zone A-D. An advantage here is the combination of the heating of a plasticizing cylinder 1 in a spiral groove, i.e., the heating cartridges embedded in the recess 5, in combination with the spirally-formed copper tubes embedded in the recesses 4, i.e., the cooling elements 6.

LIST OF REFERENCE SYMBOLS

[0049] 1 Plasticizing cylinder [0050] 2 Internal space [0051] 3 Wall [0052] 4 Recess [0053] 5 Recess [0054] 6 Cooling element [0055] 7 Heating element [0056] 8 Insulation sleeve

[0057] Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word about or approximately in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability.

[0058] As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean at least one of A, at least one of B, and at least one of C.

[0059] The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.