Device and method for the homogenisation of plastics material melts

Patent metadata

Field	Value
Publication number	US-10093034-B2
Application number	US-201514662640-A
Country	US
Kind code	B2
Filing date	Mar 19, 2015
Priority date	Mar 20, 2014
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

A device, to homogenise plastics material melts, has a homogenising element with a plurality of flow channels, which differ with respect to at least one feature from the group length, cross sectional area and cross sectional shape. When flowing through the homogenising element, the plastics material melt is divided into a plurality of part streams, which, in each case, flow through an associated flow channel. When leaving the respective flow channel the part streams have different flow speeds so the plastics material melt is expanded and sheared on transition to a uniform flow. As a result, a homogenisation of the plastics material melt takes place in a simple, efficient and effective manner.

First claim

What is claimed is:

1. A device for the homogenization of plastics material melts, the device comprising:
a housing;
at least one housing channel for a plastics material melt to be homogenized, the at least one housing channel being formed in the housing, the at least one housing channel extending from a feed opening to a discharge opening;
at least one homogenizing element comprising a plurality of flow channels for the plastics material melt to be homogenized, the flow channels extending parallel to one another and the flow channels extending parallel to a conveying direction of the plastics material melt, the flow channels ending offset at a side that is upstream in relation to the conveying direction of the plastics material melt, wherein the flow channels end flush at a side downstream in relation to the conveying direction of the plastics material melt, wherein each of the flow channels has a length defined in a channel longitudinal direction and a cross sectional area defined transverse to the channel longitudinal direction and a cross sectional shape, wherein at least some of the flow channels differ with respect to at least one of length, cross sectional area and cross sectional shape, wherein the at least one homogenizing element is arranged between the feed opening and the discharge opening, the device being configured as a screw machine, wherein at least one treatment element shaft is arranged in the at least one housing channel, the at least one treatment element shaft being rotatably drivable about an associated rotational axis, the at least one treatment element shaft comprising at least one shaft on which treatment elements are non-rotatably arranged consecutively, wherein the at least one homogenizing element extends in the at least one housing channel and the at least one treatment element shaft extends through the least one homogenizing element, wherein a mixing space is formed in a mixing zone downstream of the at least one homogenizing element, wherein no treatment elements are arranged on the at least one shaft, wherein the mixing space has a length L F in the conveying direction and there applies to the length L F in relation to a maximum dimension D of the flow channels perpendicular to the conveying direction: L F ≥2·D, so that the plastics material melt on transition to a uniform flow is subjected to an expansion and shearing.

2. A device according to claim 1 , wherein the flow channels have at least two different lengths.

3. A device according to claim 1 , wherein a ratio of a maximum length L max to a minimum length L min of the flow channels is greater than or equal to 1.2.

4. A device according to claim 1 , wherein the flow channels have a minimum length and a maximum length and at least one of the minimum length of the flow channels is greater than or equal to 10 mm, and the maximum length is less than or equal to 500 mm.

5. A device according to claim 1 , wherein the flow channels have at least two different cross sectional areas.

6. A device according to claim 1 , wherein a ratio of a maximum cross sectional area to a minimum cross sectional area of the flow channels is greater than or equal to 1.2.

7. A device according to claim 1 , wherein the flow channels have a minimum cross sectional area and a maximum cross sectional area and at least one of a minimum cross sectional area of the flow channels is greater than or equal to 5 mm 2 , and the maximum cross sectional area of the flow channels is less than or equal to 1600 mm 2 .

8. A device according to claim 1 , wherein the flow channels have at least two different cross sectional shapes.

9. A device according to claim 1 , wherein the at least one cross sectional shape of the flow channels is one of round, oval, drop-shaped and polygonal.

10. A device according to claim 1 , wherein the flow channels extend linearly in a channel longitudinal direction.

11. A device according to claim 1 , wherein the device is configured as a multi-shaft screw machine.

12. A device according to claim 1 , wherein the at least one homogenizing element is rigidly connected to the housing, wherein the at least one homogenizing element comprises a base plate which is fastened between housing portions of the housing.

13. A device according to claim 1 , wherein at least one sleeve is arranged on the at least one shaft in the mixing zone to form the mixing space.

14. A device according to claim 1 , wherein the housing has a degassing opening downstream of the at least one homogenizing element.

15. A device according to claim 14 , wherein the mixing space and the degassing opening overlap in the conveying direction.

16. A device according to claim 1 , wherein the at least one homogenizing element comprises homogenizing element structures, the homogenizing element structures defining the flow channels, each of the homogenizing element structures comprising a flow channel configuration, the flow channel configuration of one of the homogenizing element structures being different from at least the flow channel configuration of another one of the homogenizing element structures.

17. A method for the homogenization of plastics material melts, the method comprising the following steps:
providing a device and a plastics material melt, the device comprising a housing, at least one housing channel for the plastics material to be homogenized and at least one homogenizing element, the at least one housing channel being formed in the housing, the at least one housing channel extending from a feed opening to a discharge opening, the at least one homogenizing element comprising a plurality of flow channels for the plastics material melt to be homogenized, the flow channels extending parallel to one another and the flow channels extending parallel to a conveying direction of the plastics material melt, the flow channels ending offset at a side that is upstream in relation to the conveying direction of the plastics material melt, wherein the flow channels end flush at a side downstream in relation to the conveying direction of the plastics material melt, wherein each of the flow channels has a length defined in a channel longitudinal direction and a cross sectional area defined transverse to the channel longitudinal direction and a cross sectional shape, wherein at least some of the flow channels differ with respect to at least one of length, cross sectional area and cross sectional shape, the at least one homogenizing element being arranged between the feed opening and the discharge opening, the device being configured as a screw machine, wherein at least one treatment element shaft is arranged in the at least one housing channel, the treatment element shaft being rotatably drivable about an associated rotational axis, the at least one treatment element shaft comprising at least one shaft on which treatment elements are non-rotatably arranged consecutively, the at least one homogenizing element extending in the at least one housing channel and the at least one treatment element shaft extending through the least one homogenizing element, wherein a mixing space is formed in a mixing zone downstream of the at least one homogenizing element, wherein no treatment elements are arranged on the at least one shaft, the mixing space having a length in the conveying direction, the length of the mixing space being greater than or equal to two times a maximum dimension of the flow channels such that the plastics material melt on transition to a uniform flow is subject to an expansion and shearing, the maximum dimension of the flow channels being perpendicular to the

Assignees

• Coperion Gmbh

Inventors

• Ahlgrimm Michael

Classifications

• B29C48/268 Primary

  Throttling of the flow, e.g. for cooperating with plasticising elements or for degassing (flow control means B29C48/255) · CPC title

• B29C48/03

  characterised by the shape of the extruded material at extrusion · CPC title

• B29C48/375

  Plasticisers, homogenisers or feeders comprising two or more stages · CPC title

• B29C48/2552

  provided in the feeding, melting, plasticising or pumping zone, e.g. screw, barrel, gear-pump or ram · CPC title

• B29C48/256

  Exchangeable extruder parts (B29C48/691 takes precedence) · CPC title