Blade segment of disc refiner

Patent metadata

Field	Value
Publication number	US-9765479-B2
Application number	US-201514741282-A
Country	US
Kind code	B2
Filing date	Jun 16, 2015
Priority date	May 26, 2014
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

A blade segment of a disc refiner for refining fibrous material has an inner circumference and an outer circumference as well as a first side edge and a second side edge which connect the inner circumference and the outer circumference. The side edges are curved, with one convex and the other concave. The segment has a refining surface with blade bars and grooves which define a pumping direction. The side edges of the blade segment curve in the vicinity of the inner circumference in the pumping direction, and in the vicinity of the outer circumference in a non-pumping direction.

First claim

We claim:

1. A blade segment of a disc refiner intended for refining fibrous material, the blade segment comprising:
an inner circumference and an outer circumference as well as a first side edge and a second side edge which connect the inner circumference and the outer circumference;
wherein the first side edge and the second side edge of the blade segment are curved so that one side edge is concave and the other side edge is convex;
a refining surface of the blade segment, bounded by the inner circumference, the outer circumference, the first side edge, and the second side edge;
wherein the refining surface has first blade bars and first grooves which define a pumping direction;
wherein the first bars and first grooves of the blade segment curve in the vicinity of the inner circumference in the pumping direction, and in the vicinity of the outer circumference in a non-pumping direction.

2. The blade segment of claim 1 wherein the first side edge and the second side edge of the blade segment are curved side edges which have a single first radius of curvature.

3. The blade segment of claim 1 wherein the first blade bars have first refining surface portions that refine the fibrous material and first grooves that run between the first blade bars to carry fibrous material, and define a center line of the first grooves that are curved with a second radius.

4. The blade segment of claim 3 wherein the first radius of curvature and the second radius of curvature are essentially the same.

5. The blade segment of claim 3 wherein first blade bars running in a direction from the inner circumference of the blade segment to the outer circumference and the first blade grooves running in the direction from the inner circumference of the blade segment to the outer circumference of the blade segment and wherein the upper surface of the first blade bars comprises second blade bars and between them second blade grooves.

6. The blade segment of claim 5 wherein the first side edge is concave and wherein the second blade bars and the second blade grooves are directed in a direction which is the same direction as a curvature formed by the convex edge, on a side of the convex edge adjacent to the inner circumference of the blade segment.

7. The blade segment of claim 5 wherein at least one of the first side edge and the second side edge of the blade segment define an area arranged beside at least one of the first side edge and the second side edge of the blade segment, said area being free from second blade bars and second blade grooves to form at least a portion of one of the blade grooves that is formed between two of the blade segments when placed adjacently.

8. The blade segment of claim 5 wherein a cross sectional area defined by at least one of the second blade grooves changes in a run direction of the at least one second blade groove.

9. The blade segment of claim 8 wherein a depth defined by the at least one of the second blade grooves changes in the run direction of the at least one of the second blade grooves.

10. The blade segment of claim 5 wherein a cross sectional area or a depth of at least one of the first blade grooves changes in the run direction of at least one of the first blade groove blades.

11. The blade segment of claim 1 wherein in an area adjacent the outer circumference of the blade segment the non-pumping curve is 0% to 50% of a radius of the blade segment, the radius defined as perpendicular to the inner circumference and the outer circumference.

12. The blade segment of claim 11 wherein in the area adjacent the outer circumference of the blade segment the non-pumping curve is 20% to 40% of a radius of the blade segment.

13. The blade segment of claim 12 wherein in the area adjacent the outer circumference of the blade segment the non-pumping curve is about 30% of a radius of the blade segment.

14. The blade segment of claim 1 wherein the blade segment is a blade segment of a rotatable refining element.

Assignees

• SJÖSTRÖM Håkan
• Kaarineva Matti
• Iisakkila Tomi
• Valmet Technologies Inc

Inventors

• SJÖSTRÖM Håkan
• Kaarineva Matti
• Iisakkila Tomi

Classifications

• D21D1/306 Primary

  Discs · CPC title

• B02C7/12

  Shape or construction of discs · CPC title

• B02C7/02

  with coaxial discs · CPC title