Cutting insert and cutting edge-interchangeable rotary cutting tool

Patent metadata

Field	Value
Publication number	US-10850335-B2
Application number	US-201716339064-A
Country	US
Kind code	B2
Filing date	Oct 19, 2017
Priority date	Oct 21, 2016
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

This cutting insert has: as cutting edges, arcuate cutting edges that are of an arc shape protruding toward an outer circumference side of a distal end. A chisel part is formed at an intersecting ridge line part between the flank faces of the pair of arcuate cutting edges. A round honing is formed on the cutting edge tip of the arcuate cutting edge at least in a range where a radial angle is 30° or less. A curvature radius of the round honing in a cross section perpendicular to the edge length direction of the arcuate cutting edge is 20 to 40 μm. A chisel angle formed between the distal end part of the arcuate cutting edge and a chisel edge of the chisel part is 150° to 170° as seen in an insert front view.

First claim

The invention claimed is:

1. A plate-shaped cutting insert detachably mounted on a distal end part of a tool main body that is rotated about a center axis, the cutting insert comprising:
rake faces;
flank faces; and
cutting edges formed on an intersecting ridge line between the rake faces and the flank faces,
wherein: the cutting edges each have an arcuate cutting edge that is of an arc shape protruding toward an outer circumference side of a distal end of the cutting insert;
the arcuate cutting edges are formed in a pair 180° rotationally symmetric about the center axis,
a chisel part is formed at an intersecting ridge line part between the flank faces of the pair of arcuate cutting edges;
when projecting, on a reference plane including a predetermined point on the arcuate cutting edge and the center axis, an imaginary straight line passing through an arc center point of the arcuate cutting edge and the predetermined point, an angle at which the imaginary straight line is inclined with respect to the center axis in the reference plane is defined as a radial angle;
a round honing is formed on a cutting edge tip of the arcuate cutting edge when the radial angle is less than or equal to 30°;
a curvature radius of the round honing in a cross section perpendicular to a cutting edge length direction of the arcuate cutting edge is 20 to 40 μm;
a chisel angle formed between the distal end part of the arcuate cutting edge and a chisel edge of the chisel part is 150° to 170° as seen in an insert front view of the cutting insert viewed from the distal end toward the proximal end side in the center axis direction;
the pair of the arcuate cutting edges are connected to both ends of the chisel edge in the ridge line direction, and
a clearance angle of the chisel edge gradually becomes greater from one arcuate cutting edge of the pair of arcuate cutting edges having a flank face in common with the flank face of the chisel edge, toward the other arcuate cutting edge along the ridge line direction.

2. The cutting insert according to claim 1 , wherein the curvature radius of the round honing gradually decreases from a distalmost end toward an outermost circumferential point side along the edge length direction of the arcuate cutting edge.

3. The cutting insert according to claim 1 , wherein the round honing is formed over an entire region in an edge length direction of the arcuate cutting edge.

4. The cutting insert according to claim 1 ,
wherein a tool cutting edge diameter D (mm) of the cutting insert is 6 to 50 mm, and as seen in the insert front view, a chisel thickness L 1 (mm) along a width direction of the chisel part perpendicular to the edge length direction of the distal end part of the arcuate cutting edge satisfies 0.007×D≤L 1 ≤0.024×D.

5. The cutting insert according to claim 1 ,
wherein, as seen in the insert front view, a linear ridge line part extending on an extension line of the arcuate cutting edge along the edge length direction of the distal end part of the arcuate cutting edge is formed on the chisel part,
and a chisel intersection amount, which is a distance from an end edge on a side opposite to the distalmost end of the arcuate cutting edge in the ridge line part along the edge length direction to the central axis is 0.10 to 0.20 mm.

6. The cutting insert according to claim 1 ,
wherein a clearance angle at a distal end part of the arcuate cutting edge is less than 15°.

7. The cutting insert according to claim 1 ,
wherein a helical angle at an outermost circumferential point of the arcuate cutting edge is 26° to 32°.

8. The cutting insert according to claim 1 , wherein the arcuate cutting edge is of an arc shape protruding in a tool rotation direction about the center axis, and a most protruding point of the arcuate cutting edge that protrudes most in the tool rotation direction is arranged in a range where the radial angle is 30 degree to 47 degree.

9. The cutting insert according to claim 8 , wherein, in a virtual plane perpendicular to the reference plane and including the imaginary straight line, a true rake angle, which is an angle at which the rake face of the arcuate cutting edge is inclined with respect to the reference plane, is defined as a radial rake angle; the radial rake angle at a radial angle of 0 degree is greater than the radial rake angle at a radial angle of 90 degree and is less than or equal to the radial rake angle at the most protruding point; the maximum value of the radial rake angle is set to a range where the radial angle is 20 degree to 40 degree; and the radial rake angle gradually becomes smaller from the most protruding point toward an outermost circumferential point of the arcuate cutting edge.

10. The cutting insert according to claim 1 ,
wherein of both faces facing in a thickness direction of the cutting insert, a face facing the same direction as the rake face is treated as a front face, and a face facing in a direction opposite to the rake face is treated as a back face, and
a distance from an outermost circumference point to the back face along the thickness direction is greater than a distance from an outermost circumference point of the arcuate cutting edge along the thickness direction to the front face.

11. A cutting edge-interchangeable rotary cutting tool comprising:
a tool main body that is rotated about a center axis;
a mounting seat formed at a distal end part in a direction of the center axis of the tool main body; and
a cutting insert that is detachably attached to the mounting seat and that has cutting edges;
wherein the cutting insert of claim 1 is used as the cutting insert.

12. The cutting insert according to claim 2 , wherein the round honing is formed over the entire region in an edge length direction of the arcuate cutting edge.

13. The cutting insert according to claim 2 ,
wherein a tool cutting edge diameter D (mm) of the cutting insert is 6 to 50 mm, and as seen in the insert front view, a chisel thickness L 1 (mm) along a width direction of the chisel part perpendicular to the edge length direction of the distal end part of the arcuate cutting edge satisfies 0.007×D≤L 1 ≤0.024×D.

14. The cutting insert according to claim 2 ,
wherein, as seen in the insert front view, a linear ridge line part extending on an extension line of the arcuate cutting edge along the edge length direction of the distal end part of the arcuate cutting edge is formed on the chisel part,
and a chisel intersection amount, which is a distance from an end edge on a side opposite to the distalmost end of the arcuate cutting edge in the ridge line part along the edge length direction to the central axis is 0.10 to 0.20 mm.

15. The cutting insert according to claim 2 ,
wherein a clearance angle at a distal end part of the arcuate cutting edge is less than 15°.

16. The cutting insert according to claim 2 ,
wherein a helical angle at an outermost circumferential point of the arcuate cutting edge is 26° to 32°.

17. The cutting insert according to claim 6 ,
wherein a helical angle at an outermost circumferential point of the arcuate cutting edge is 26° to 32°.

18. The cutting insert according to claim 2 ,
wherein the arcuate cutting edge is of an arc shape protruding in a tool rotation direction about the center axis, and
a most protruding point of the arcuate cutting edge that protrudes most in the tool rotation direction is arranged in a range where the radial angle is 30° to 47°.

19. The cutting insert according to claim 2 ,
wherein of both faces facing

Assignees

• Mitsubishi Hitachi Tool Eng Ltd

Inventors

• Kiuchi Yasuhiro
• Kobayashi Yoshiyuki
• Nakamigawa Takao

Classifications

• B23C5/202 Primary

  Plate-like cutting inserts with special form (special form related to securing of the insert B23C5/22) · CPC title

• B23C5/1036 Primary

  having a single cutting insert, the cutting edges of which subtend 180 degrees · CPC title

• B23C2210/54

  Configuration of the cutting part · CPC title

• B23C2200/203

  Curved cutting edges · CPC title

• B23C5/1027

  with one or more removable cutting inserts · CPC title