Extruder including an improved homogenising member and method for extruding a viscous material

Patent metadata

Field	Value
Publication number	US-10239249-B2
Application number	US-201415106734-A
Country	US
Kind code	B2
Filing date	Dec 19, 2014
Priority date	Dec 20, 2013
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

An Extruder for shaping a viscous material such as a blend of rubber is disclosed herein. The extruder includes a screw rotationally driven about an axis (XX′) in a barrel and bearing one or more helical flights extending radially outwards from a central shaft of the screw, the extruder comprising a material homogenization zone (H) through which a screw portion comprising interrupted flight elements forming empty annular spaces extends axially, and a barrel portion delimiting the said homogenization zone bearing flight elements extending radially inwards into the said empty annular spaces. According to the disclosure, the barrel portion delimiting the homogenization zone is itself rotationally driven about the axis XX′ to form a rotary barrel.

First claim

The invention claimed is:

1. An extruder for shaping a viscous material such as a blend of rubber, comprising:
a screw rotationally driven by a first motor unit about an axis (XX′) in a barrel and bearing one or more helical flights extending radially outwards from a central shaft of the screw, the extruder includes a material homogenization zone (H) through which a screw portion comprising interrupted flight elements forming empty annular spaces that extends axially, and
a barrel portion delimiting the said homogenization zone bearing flight elements extending radially inwards into the said empty annular spaces beyond the vertices of the flight elements of the screw,
wherein the barrel portion delimiting the homogenization zone is itself rotationally driven by a second motor unit about the axis XX′ to form a rotary barrel.

2. The extruder according to claim 1 , wherein the homogenization zone of the screw comprises at least one ring mounted on the screw comprising the said flight elements which are imbricated between the said flight elements borne by a barrel-forming ring.

3. The extruder according to claim 1 , wherein the diameter of the screw in the zone of the extruder that lies upstream of the homogenization zone is less than the diameter of the screw in the homogenization zone.

4. The extruder according to claim 1 , wherein the homogenization zone (H) is positioned, with respect to the direction of extrusion of the endless screw, in the downstream part of the extruder.

5. The extruder according to claim 1 , wherein the flight elements borne by the rotary barrel form, with the axis of rotation XX′, a positive angle (a) such that they are organized in a helix oriented in the same direction as the direction of the helix formed by the flights of the screw.

6. The extruder according to claim 1 , wherein the flight elements borne by the rotary barrel form, with the axis of rotation XX′, a negative angle (a′) such that they are organized in a helix oriented in the opposite direction to the direction of the helix formed by the flights of the screw.

7. The extruder according to claim 1 , wherein the flight elements borne by the rotary barrel form, with the axis of rotation XX′, a zero angle.

8. The extruder according to claim 1 , wherein one or more flight elements borne by the rotary barrel are individually rotationally driven on themselves about a radial axis.

9. The extruder according to claim 1 , wherein the homogenization zone (H), the flight elements of the screw and of the rotary barrel have the form of a blade comprising at least one cutting edge facing the upstream end of the homogenization zone with respect to the direction of extrusion.

10. The extruder according to claim 1 , wherein the flight elements borne by the rotary barrel are pins of substantially cylindrical shape.

11. A method for extruding a viscous material such as a blend of rubber, characterized in that use is made of an extruder according to claim 1 , in which the speed of the rotary barrel with respect to the speed of the screw and/or the direction of rotation of the barrel with respect to the screw is/are varied in order to alter the rheological state of the viscous material flowing through the homogenization zone.

12. The method according to claim 11 , wherein the difference in rotational speed between the screw and the rotary barrel is controlled as a function of the temperature of the viscous material at the inlet to the homogenization zone.

13. The method according to claim 11 , wherein the difference in rotational speed between the screw and the rotary barrel is controlled as a function of the roughness of the material at the outlet of the extruder.

14. The method according to claim 11 , wherein the difference in rotational speed between the screw and the rotary barrel is controlled as a function of the variation in efficiency of the extruder.

15. The method according to claim 11 , wherein the rotary barrel rotates in the same direction of rotation as the screw at the same or a higher speed.

16. The method according to claim 11 , wherein after the extruder has been stopped for some time, the rotary barrel is made to rotate while keeping the screw stationary, so as to raise the temperature of the viscous material contained in the homogenization zone again.

17. The method according to claim 11 , wherein the rotary barrel rotates at a rotational speed lower than the rotational speed of the screw or in the opposite direction to the direction of rotation of the screw.

18. The method according to claim 11 , wherein the rotary barrel is rotationally driven solely under the effect of the forward motion of the viscous material propelled by the rotation of the screw and flowing in the homogenization zone.

19. The method according to claim 18 , wherein a braking torque is applied to the rotary barrel so that the rotational speed of the rotary barrel is lower than the rotational speed of the screw.

20. The method according to claim 11 , wherein the screw and the rotary barrel are made to rotate alternately in the same direction and in opposite directions in order successively to empty the various stages of flights situated in the homogenization zone.

21. The method according to claim 11 , wherein power is added to an extruder in order to increase its throughputs by adding a rotary barrel that is motorized so as to supply the blend with energy in addition to that supplied by the screw of the extruder.

22. The extruder according to claim 1 , wherein the first motor unit and the second motor unit are arranged to drive the rotary barrel and screw in opposite rotational directions.

23. The extruder according to claim 1 , wherein the first motor unit and the second motor unit are arranged to drive the rotary barrel and screw in the same rotational direction.

24. The extruder according to claim 1 , wherein the first motor unit and the second motor unit are arranged to drive the rotary barrel and screw at different rotational speeds.

Assignees

• Michelin & Cie
• Michelin Rech Tech

Inventors

• Vignon Fabien
• Lhospitalier Jean-Francois

Classifications

• B29C48/575

  provided with elements of a generally circular cross-section for shearing the melt, i.e. shear-ring elements · CPC title

• B29K2021/00

  Use of unspecified rubbers as moulding material · CPC title

• B29C48/92 Primary

  Measuring, controlling or regulating · CPC title

• B29C2948/92209

  Temperature · CPC title

• B29C48/686

  having grooves or cavities · CPC title