Single-screw extruder and a method for extrusion

Patent metadata

Field	Value
Publication number	US-12115508-B2
Application number	US-202017422066-A
Country	US
Kind code	B2
Filing date	Jan 10, 2020
Priority date	Jan 11, 2019
Publication date	Oct 15, 2024
Grant date	Oct 15, 2024

Abstract

A single-screw extruder and method are disclosed wherein the extruder includes a cylindrical rotor member arranged in a barre, and a drive system for rotation of the rotor member in the barrel. The extruder includes an outlet-provided with a die, having an outer ring arranged to the barrel, and an inner die part, the die establishing a flow channel that is continuously circular in all its cross-sections.

First claim

The invention claimed is:

1. A single-screw extruder, comprising:
a cylindrical rotor member having a diameter (D) and a length (L) and including a feeding zone;
the rotor member being arranged in a barrel;
a cylindrical surface of the rotor member carrying cavity/cavities and/or projection(s) arranged in helically extending rows;
the helically extending row(s) of the rotor member having a pitch (P) and depth (d) in the feeding zone of the rotor member;
a drive system for rotation of the rotor member in the barrel, wherein:
a relation of a depth (d) to diameter (D) of the rotor member d:D is not more than 1:20; and
a relation of the pitch (P) of the helically extending rows of the rotor member to the diameter (D) of the rotor member P:D is not more than 1:4; and
an outlet of the extruder, is provided with a die including:
an outer ring arranged relative to the barrel; and
an inner die part arranged relative to the cylindrical rotor member to rotate therewith; and
the die being configured for establishing a flow channel that is continuously circular in all its cross-sections.

2. The extruder as claimed in claim 1 , wherein at least one of the outer ring and the inner die part is removably attached to the extruder.

3. The extruder as claimed in claim 1 , wherein at least one of the outer ring and the inner die part is fixedly attached to the extruder.

4. The extruder as claimed in claim 1 , wherein a flow surface of the outer ring is essentially smooth.

5. The extruder as claimed in claim 4 , wherein the flow surface of the outer ring comprises:
corrugations that differ from an inner surface of the barrel.

6. The extruder as claimed in claim 4 , wherein the flow surface of the inner die part comprises:
corrugations having a shape and/or dimensions differing from those of the cavity/cavities and/or projection(s) arranged on the rotor member.

7. The extruder as claimed in claim 1 , wherein a flow surface of the inner die part is essentially smooth.

8. The extruder as claimed in claim 1 , wherein a cross-sectional area of the flow channel of the die is constant over a length of the die.

9. The extruder as claimed in claim 1 , wherein the outer ring comprises:
at least one radial opening as a material output port; and
a blocking means for blocking an end of the flow channel after the at least one radial opening being arranged in the die.

10. The extruder as claimed in claim 9 , wherein the blocking means comprises:
a reverse thread, a pitch of which is arranged in an opposite direction as the pitch of the cavity/cavities and/or projection(s) arranged in the helically extending rows, and wherein:
the reverse thread establishes a reverse screw channel with an outer surface of the outer ring.

11. The extruder as claimed in claim 9 , wherein the blocking means comprises:
a cooling arrangement arranged to cool the outer ring.

12. A single-screw extruder, comprising:
a cylindrical rotor member having a diameter (D) and a length (L) and including a feeding zone;
the rotor member being arranged in a barrel;
a cylindrical surface of the rotor member carrying cavity/cavities and/or projection(s) arranged in helically extending rows;
the helically extending row(s) of the rotor member having a pitch (P) and depth (d) in the feeding zone of the rotor member;
a drive system for rotation of the rotor member in the barrel, wherein:
a relation of a depth (d) to a diameter (D) of the rotor member d:D is not more than 1:20; and
a relation of the pitch (P) of the helically extending rows of the rotor member to the diameter (D) of the rotor member P:D is not more than 1:4;
the rotor member includes a cylindrical channel, a diameter of which is at least 75% of the diameter (D) of the rotor member; and
an outlet of the extruder, provided with a die, the die including:
an outer ring and an inner die part creating a flow channel that is continuously circular in all its cross-sections;
the outer ring being attached to the barrel; and
the inner die part being supported to a support structure that is arranged inside said cylindrical channel;
the rotor member being arranged rotable with respect to the inner die part.

13. The extruder as claimed in claim 12 , wherein an inner surface of a section of the cylindrical channel lying in proximity of the die comprises;
a counter thread, a pitch of which is arranged in a same direction as the pitch of the cavity/cavities and/or projection(s) arranged in the helically extending rows; and wherein
the counter thread establishes a counter screw channel with an outer surface of the support structure.

14. The extruder as claimed in claim 12 , wherein the outer ring comprises:
at least one radial opening as a material output port; and
a blocking means for blocking an end of the flow channel after the at least one radial opening being arranged in the die.

15. The extruder as claimed in claim 14 , wherein the blocking means comprises:
a reverse thread, a pitch of which is arranged in an opposite direction as the pitch of the cavity/cavities and/or projection(s) arranged in the helically extending rows; wherein
the reverse thread establishes a reverse screw channel with an inner surface of the outer ring.

16. The extruder as claimed in claim 14 , wherein the blocking means comprises:
a cooling arrangement arranged to cool the outer ring.

17. The extruder as claimed in claim 12 , wherein a diameter of the cylindrical channel is 80% of the diameter (D) of the rotor member.

18. A method for extrusion, the method comprising:
A) feeding material in a single-screw extruder, the extruder including:
a cylindrical rotor member having a diameter (D) and a length (L) and including a feeding zone;
the rotor member being arranged in a barrel;
the cylindrical surface of the rotor member carrying cavity/cavities and/or projection(s) arranged in helically extending rows;
the helically extending row(s) of the rotor member having a pitch (P) and depth (d) in the feeding zone of the rotor member;
a drive system for the rotation of the rotor member in the barrel, wherein:
a relation of the depth (d) to the diameter (D) of the rotor member d:D is not more than 1:20; and
a relation of the pitch (P) of the helically extending rows of the rotor member to the diameter (D) of the rotor member P:D is not more than 1:4;
B) heating the material in said single-screw extruder to a flowable state;
C) feeding the material into an outlet of the extruder, the outlet being provided with a die including:
an outer ring arranged relative to the barrel; and
an inner die part arranged relative to the cylindrical rotor member to rotate therewith;
the die establishing a flow channel that is continuously circular in all its cross-sections; and
D) allowing the material to exit between the outer ring and the rotating inner die part.

19. A method for extrusion, the method comprising:
A) feeding material in a single-screw extruder, the extruder including:
a cylindrical rotor member having a diameter (D) and a length (L) and including a feeding zone;
the rotor member being arranged in a barrel;
the cylindrical surface of the rotor member carrying cavity/cavities and/or projection(s) arranged in helically extending rows;
the helically extending row(s) of the rotor member having a pitch (P) and depth (d) in the feeding zone of the rotor member;
a drive system for rotation of the rotor member in the barrel, wherein;
a relation of the depth (d) to the diameter (D) of the rotor member d:D is not

Assignees

• Teknologian Tutkimuskeskus Vtt Oy

Inventors

• Minkkinen Hannu
• Mannila Juha

Classifications

• B01F2215/0431

  Numerical size values, e.g. diameter of a hole or conduit, area, volume, length, width, or ratios thereof · CPC title

• B01F23/43

  using driven stirrers · CPC title

• B01F35/92

  for heating the outside of the receptacle, e.g. heated jackets or burners · CPC title

• B01F2101/2805

  Mixing plastics, polymer material ingredients, monomers or oligomers · CPC title

• B01F2035/98

  Cooling · CPC title