Single-sided four-way indexable positive cutting insert and insert mill therefor

Patent metadata

Field	Value
Publication number	US-10406609-B2
Application number	US-201715827291-A
Country	US
Kind code	B2
Filing date	Nov 30, 2017
Priority date	Nov 30, 2017
Publication date	Sep 10, 2019
Grant date	Sep 10, 2019

Abstract

A single-sided four-way indexable cutting insert includes a positive basic shape, a rake surface, a peripheral surface including four side abutment surfaces, a base bearing surface and a screw hole connecting the rake and base bearing surfaces. The insert has an imaginary square frustum which defines a square base containing the cutting insert's base bearing surface, and further defines four isosceles trapezoid side surfaces respectively containing the cutting insert's four side abutment surfaces. A material volume VF of the cutting insert and a void volume VS of the insert fulfill the condition VS/VF≥0.25.

First claim

What is claimed is:

1. A single-sided, four-way indexable cutting insert having a positive basic shape and comprising:
a rake surface;
a base bearing surface located opposite the rake surface;
an insert axis A I extending perpendicular to the base bearing surface and through the center of the insert, the insert axis defining: an upward direction from the base bearing surface towards the rake surface, a downward direction opposite to the upward direction, and an outward direction perpendicular to the upward and downward directions and extending away from the insert axis;
a cutting insert height H I measurable parallel to the insert axis, from the base bearing surface to a highest point of the rake surface;
a peripheral surface connecting the rake surface and base bearing surface, the peripheral surface comprising:
an unground lower sub-surface which extends upwardly and outwardly from the base bearing surface, the lower sub-surface comprising first, second, third and fourth side abutment surfaces; and
an upper sub-surface connecting the lower sub-surface and the rake surface, the upper sub-surface beginning in the upward direction at a minimum upper surface height H U above the base bearing surface;

a cutting edge formed along an intersection of the peripheral surface and rake surface;
a screw hole opening out to the rake and base bearing surfaces, the screw hole having a void volume V S ; wherein:
the insert has an imaginary square frustum defined by:
a square base containing the base bearing surface;
four isosceles trapezoid side surfaces, each extending upwardly and outwardly from the square base at an abutment surface relief angle θ fulfilling the condition 1°≤θ≤15°, and each containing a respective one of the first, second, third and fourth side abutment surfaces; and
a square top connecting the four isosceles trapezoid side surfaces and located a distance equal to the cutting insert height H I from the square base;

the upper sub-surface comprises at least one overhanging portion, which extends outwardly from an adjacent one of the trapezoid side surfaces and has a lowermost point at said minimum upper sub-surface height H U ;
in a view parallel to the insert axis A I , an inscribed circle diameter I C of the cutting edges fulfills the condition I C ≤10 mm; and
a volume ratio V S /V F of the void volume V S and a material volume V F of the cutting insert fulfills the condition V S /V F ≥0.25.

2. The cutting insert according to claim 1 , wherein the volume ratio fulfills the condition: V S /V F ≥0.30.

3. The cutting insert according to claim 1 , wherein the volume ratio fulfills the condition: V S /V F ≤0.60.

4. The cutting insert according to claim 1 , wherein the inscribed circle diameter I C fulfills the condition: I C ≤8 mm.

5. The cutting insert according to claim 4 , wherein the inscribed circle diameter I C fulfills the condition: I C ≤6.5 mm.

6. The cutting insert according to claim 5 , wherein the inscribed circle diameter I C fulfills the condition: I C ≤5 mm.

7. The cutting insert according to claim 1 , wherein the inscribed circle diameter I C fulfills the condition: I C ≥3.5 mm.

8. The cutting insert according to claim 1 , wherein the minimum upper sub-surface height H U fulfills the condition: 0.60H I ≤H U ≤0.90 H I .

9. The cutting insert according to claim 8 , wherein the minimum upper sub-surface height H U fulfills the condition: 0.63H I ≤H U ≤0.73H I .

10. The cutting insert according to claim 1 , wherein the at least one overhanging portion is a plurality of overhanging portions.

11. The cutting insert according to claim 1 , wherein the cutting edge comprises four identical corners and four identical straight edges connecting the corners.

12. The cutting insert according to claim 11 , wherein each straight edge has an edge length L E which fulfills the condition: 0.65I C <L E <0.951 C .

13. The cutting insert according to claim 12 , wherein each straight edge has an edge length L E which fulfills the condition: 0.75I C <L E <0.901 C .

14. The cutting insert according to claim 1 , wherein only the base bearing surface of the cutting insert is ground.

15. The cutting insert according to claim 14 , wherein the cutting edge is contained within the square top.

16. The cutting insert according to claim 1 , wherein the base bearing surface and the entire cutting edge are ground and the cutting edge is contained within the square top.

17. The cutting insert according to claim 1 , wherein the cutting edge is circular.

18. The cutting insert according to claim 1 , wherein the abutment surface relief angle θ fulfills the condition 4°≤θ≤7°.

19. An insert mill comprising:
a tool holder; and
a cutting insert according to claim 1 seated in the tool holder;
the tool holder comprising:
a shank portion;
a cutting portion connected to the shank portion and comprising a pocket; and
a rotation axis extending through the center of the tool holder and defining a forward direction extending from the shank portion in the direction of the cutting portion;

the pocket comprises:
a seat abutment surface;
a threaded pocket hole opening out to the seat abutment surface and defining a minimal pocket hole inscribed circle I P and an associated minimal pocket hole diameter D P ; and
first and second lateral abutment surfaces oriented at a right angle to each other in a plan view of the seat abutment surface;

each of the first and second lateral abutment surfaces has an elongated continuous shape, the first and second lateral abutment surfaces being the only abutment surfaces of the pocket apart from the seat abutment surface; and
the cutting insert is mounted to the pocket with the insert's base bearing surface abutting the pocket's seat abutment surface, and two of the insert's adjacent side abutment surfaces abutting the pocket's first and second lateral abutment surfaces.

20. The insert mill according to claim 19 , wherein:
the cutting edge is circular; and
the insert's two adjacent side abutment surfaces abut center portions of the pocket's first and second lateral abutment surfaces.

Assignees

• Iscar Ltd

Inventors

• Ballas Assaf

Classifications

• B23C2200/0455

  Square · CPC title

• B23C2210/0407

  Cutting angles · CPC title

• B23C5/06

  Face-milling cutters, i.e. having only or primarily a substantially flat cutting surface · CPC title

• B23C2200/085

  discontinuous · CPC title

• B23C2200/125

  discontinuous · CPC title