Coated PCBN cutting inserts

• US 6,599,062 B1
• Filed: 05/15/2000
• Issued: 07/29/2003
• Est. Priority Date: 06/11/1999
• Status: Expired due to Term

• Current Assignee: Kennametal Incorporated
• Original Assignee: Kennametal Incorporated
• Inventors: Reiner, Kent L., Mohrbach, Edward T., Oles, Edward J., Gates, Alfred S. Jr.
• Primary Examiner(s): TSAI, HENRY
• Application Number:
  US09/571,695
• Time in Patent Office: 1,170 Days
• Field of Search: 407/118, 407/119, 407/120, 408/144, 408/145, 428/697, 428/698, 428/699
• US Class Current: 407/119
• CPC Class Codes: B23B 2222/28 Details of hard metal, i.e. cemented carbide
• CPC Class Codes: B23B 2224/04 Aluminium oxide
• CPC Class Codes: B23B 2224/28 Titanium carbide
• CPC Class Codes: B23B 2224/32 Titanium carbide nitride (TiCN)
• CPC Class Codes: B23B 2224/36 Titanium nitride
• CPC Class Codes: B23B 2226/125 cubic [CBN]
• CPC Class Codes: B23B 2228/04 applied by chemical vapour deposition [CVD]
• CPC Class Codes: B23B 2240/08 Brazed connections
• CPC Class Codes: B23B 27/145 characterised by having a special shape
• CPC Class Codes: C04B 41/4529 applied from the gas phase
• CPC Class Codes: C04B 41/5031 Alumina
• CPC Class Codes: C04B 41/5061 Titanium carbide
• CPC Class Codes: C04B 41/5063 Aluminium nitride
• CPC Class Codes: C04B 41/5068 Titanium nitride
• CPC Class Codes: C04B 41/52 Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
• CPC Class Codes: C04B 41/522 Multiple coatings, for one of the coatings of which at least one alternative is described
• CPC Class Codes: C04B 41/87 Ceramics
• CPC Class Codes: C04B 41/89 for obtaining at least two superposed coatings having different compositions
• CPC Class Codes: Y10T 407/26 comprising cutting edge bonded to tool shank
• CPC Class Codes: Y10T 407/27 comprising tool of specific chemical composition

Abstract

A cutting tool and method for machining hardened steel including a substrate of polycrystalline cubic boron nitride having one or more layers of a hard refractory coating containing aluminum. The coating may contain a titanium aluminum nitride layer applied by a physical vapor deposition (PVD). Alternatively, the coating may include a layer of aluminum oxide applied by chemical vapor deposition.

Claims

1. A coated cutting tool for machining hardened steel comprising:

a substrate comprising polycrystalline cubic boron nitride having a rake surface and a flank surface and a cutting edge for machining hardened steel having a Rockwell C hardness greater than 45; and

a coating applied to said substrate by one of a PVD or CVD technique, or a combination thereof, comprising at least one layer containing Al.

2. The coated cutting tool as claimed in claim 1 wherein said coating further includes at least one layer selected from the group consisting of titanium nitride, titanium carbide, titanium carbonitride, and titanium oxycarbonitride.

3. The coated cutting tool as claimed in claim 1 wherein said coating further comprising at least one layer of an aluminum oxide.

4. The coated cutting tool as claimed in claim 3 wherein said coating further comprises a plurality of layers of aluminum oxide applied by a chemical vapor deposition technique.

5. The coated cutting tool according to claim 3 wherein the coating comprising at least one layer of titanium aluminum nitride.

6. The coated cutting tool as claimed in claim 1 wherein said coating comprises at least one layer of a titanium aluminum nitride.

7. The coated cutting tool as claimed in claim 1 wherein said coating is about 2-20 μ

m in thickness.

8. The coated cutting tool of claim 1 wherein the substrate includes a rake surface having a surface roughness of less than or equal to 10 microinches R_a.

9. The coated cutting tool of claim 8 wherein said coating is about 2-5 μ

m in thickness.

10. The coated cutting tool of claim 1 wherein the machining is a finish machining operation having a depth of cut of 0.050 inches or less.

11. The coated cutting tool of claim 1 wherein the coating comprises a titanium aluminum nitride coating having an Al/Ti ratio of 0.8 to 0.55 on an atomic basis.

12. The coated cutting tool according to claim 11 wherein the coating comprises a titanium aluminum nitride coating directly bonded to the polycrystalline cubic boron nitride and having a Rockwell A indent adhesion strength of greater than or equal to 60 kg.

13. The coated cutting tool according to claim 1 wherein the coating comprises a titanium aluminum nitride coating directly bonded to the polycrystalline cubic boron nitride and having a Rockwell A indent adhesion strength of greater than or equal to 60 kg to a rake surface of said substrate, said rake surface having a surface roughness of less than or equal to 10 microinches R_a.

14. The coated cutting tool according to claim 13 wherein the titanium aluminum nitride coating has an Al/Ti ratio of 0.8 to 0.6 on an atomic basis.

15. A coated cutting tool for machining hardened material having a hardness value greater than about 45 R_c comprising:

a substrate comprising polycrystalline cubic boron nitride having a rake surface with a surface roughness of no greater than about 10 microinches R_a;

a coating of about 2-20 μ

m in thickness applied to said substrate by one of a PVD or CVD technique comprising at least one layer containing Al; and

said coating having a Rockwell A indent adhesion strength of greater than or equal to 60 kg to said rake surface of said substrate.

16. The cutting tool of claim 15 wherein the coating comprises at least one layer of a titanium aluminum nitride.

17. The coated cutting tool according to claim 16 wherein the coating comprising at least one layer of aluminum oxide applied by said PVD technique.

18. The coated cutting tool as claimed in claim 15 wherein said coating further includes at least one layer selected from the group consisting of titanium nitride, titanium carbide, titanium carbonitride, and titanium oxycarbonitride.

19. The coated cutting tool as claimed in claim 15 wherein said coating further comprising at least one layer of an aluminum oxide.

20. The coated cutting tool as claimed in claim 19 wherein said coating further comprises a plurality of layers of aluminum oxide applied by a chemical vapor deposition technique.

21. A method of finish machining a hardened steel having a hardness greater than 45 R_c comprising the steps of:

providing a coated cutting tool comprising a brazed substrate of polycrystalline cubic boron nitride brazed to a cemented carbide substrate, said brazed substrate having a coating comprising at least one layer containing Al applied thereto by one of a PVD or CVD technique or a combination thereof; and

machining the hardened steel using said coating cutting tool at a depth of cut of no more than 0.050 inch.

22. The method of claim 21 wherein said coating includes at least one layer selected from the group consisting of a titanium nitride, titanium carbide, titanium carbonitride, and titanium oxycarbonitride.

23. The method of claim 21 wherein said coating further comprising at least one layer of an aluminum oxide.

24. The method of claim 23 wherein said coating further comprises a plurality of layers of aluminum oxide applied by a chemical vapor deposition technique.

25. The method of claim 21 wherein said coating comprises at least one layer of a titanium aluminum nitride.

26. The method according to claim 25 wherein the coating comprises at least one layer of aluminum oxide applied by said PVD technique.

27. The method of claim 21 wherein said polycrystalline cubic boron nitride substrate has a rake surface roughness of no more than about 10 microinches R_a.

28. The method of claim 21 wherein said polycrystalline cubic boron nitride substrate has a rake surface roughness of no more than 8 microinches R_a.

29. The method of claim 21 wherein the coating has a thickness of about 2-20 μ

m.

30. A coated cutting tool for machining hardened steel comprising:

a composite insert comprising a body made from a WC containing material having a substrate of a polycrystalline boron nitride material brazed therein and defining a cutting edge on said substrate;

said body having a rake surface and a flank surface bordering said substrate, wherein said rake surface has a surface roughness in an uncoated condition of no more than about 10 microinches Ra;

a coating applied to said substrate by a PVD technique in a thickness of about 2-5 μ

m comprising at least one layer containing Al; and

said coating having a Rockwell A indent adhesion strength of greater than or equal to 60 kg to said rake surface of said substrate.

31. The coated cutting tool of claim 30 wherein said coating further includes at least one layer containing a titanium nitride.

32. The coated cutting tool of claim 30 wherein said coating further includes at least one layer containing a titanium aluminum nitride.

33. The coated cutting tool according to claim 32 wherein said coating further includes at least one layer containing an aluminum oxide.

34. The coated cutting tool of claim 30 wherein said coating has a thickness of 3-4 μ

m.

35. The coated cutting tool of claim 34 wherein said substrate has a rake surface roughness of no greater than 8 microinches R_a.