Surface-covered cubic boron nitride sintered body tool and method of manufacturing the same

Abstract

A surface-covered CBN sintered body tool includes a base material formed with a cubic boron nitride (CBN) sintered body and a surface covering film covering a surface of the base material, and has a nega-land exposing the CBN sintered body in at least a portion thereof and a flank having the surface covering film formed thereon. With this, the surface-covered CBN sintered body tool having high defect resistance and wear resistance can be provided. The surface covering film preferably includes a nitride or a carbonitride of a compound including at least one element selected from the group consisting of Ti, Cr, Zr, and V and at least one element selected from the group consisting of Al, Si and B, or a nitride or a carbonitride of Ti.

1 . A surface-covered cubic boron nitride sintered body tool, comprising:
 a base material formed with a cubic boron nitride sintered body; and   a surface covering film covering a surface of the base material; wherein   a nega-land exposing the cubic boron nitride sintered body in at least a portion thereof associated with a cutting cross section and a flank having the surface covering film are formed.   
     
     
         2 . (canceled) 
     
     
         3 . The surface-covered cubic boron nitride sintered body tool according to  claim 1 , wherein
 the cubic boron nitride sintered body is exposed in a whole portion of the nega-land.   
     
     
         4 . The surface-covered cubic boron nitride sintered body tool according to  claim 3 , wherein
 the nega-land has a width W of 0.05-0.2 mm.   
     
     
         5 . The surface-covered cubic boron nitride sintered body tool according to  claim 1 , wherein
 arithmetic mean surface roughness Ra of a portion of the nega-land exposing the cubic boron nitride sintered body is expressed as 0.3≦Ra(min)/Ra(max)≦0.8, where Ra(min) represents surface roughness in a direction parallel to a grinding direction of a grinder and Ra(max) represents surface roughness in a direction perpendicular to the grinding direction of the grinder.   
     
     
         6 . The surface-covered cubic boron nitride sintered body tool according to  claim 1 , wherein
 the surface covering film includes a nitride or a carbonitride of a compound including at least one element selected from the group consisting of Ti, Cr, Zr, and V and at least one element selected from the group consisting of Al, Si and B, or a nitride or a carbonitride of Ti.   
     
     
         7 . (canceled) 
     
     
         8 . The surface-covered cubic boron nitride sintered body tool according to  claim 6 , wherein
 arithmetic mean surface roughness Ra of a portion of the nega-land exposing the cubic boron nitride sintered body is expressed as 0.3 Ra(min)/Ra(max)  0 . 8 , where Ra(min) represents surface roughness in a direction parallel to a grinding direction of a grinder and Ra(max) represents surface roughness in a direction perpendicular to the grinding direction of the grinder.   
     
     
         9 . The surface-covered cubic boron nitride sintered body tool according to  claim 6 , wherein
 the cubic boron nitride sintered body is exposed in a whole portion of the nega-land.   
     
     
         10 . The surface-covered cubic boron nitride sintered body tool according to  claim 9 , wherein
 the nega-land has a width W of 0.05-0.2 mm.   
     
     
         11 . A surface-covered cubic boron nitride sintered body tool, comprising:
 a base material formed with a cubic boron nitride sintered body; and   a surface covering film covering a surface of the base material; wherein   a nega-land exposing the cubic boron nitride sintered body in at least a portion thereof associated with a cutting cross section and a flank having the surface covering film are formed, and   a cubic boron nitride particle in said cubic boron nitride sintered body exposed contains at least one of Ti, Cr, Zr, V, and Ar at a depth of at least 0.05 μm from a surface of the cubic boron nitride particle with a total content of at most an amount of an unavoidable impurity.   
     
     
         12 . The surface-covered cubic boron nitride sintered body tool according to  claim 11 , wherein
 the surface covering film includes a nitride or a carbonitride of a compound including at least one element selected from the group consisting of Ti, Cr, Zr, and V and at least one element selected from the group consisting of Al, Si and B, or a nitride or a carbonitride of Ti.   
     
     
         13 . (canceled) 
     
     
         14 . The surface-covered cubic boron nitride sintered body tool according to  claim 12 , wherein
 arithmetic mean surface roughness Ra of a portion of the nega-land exposing the cubic boron nitride sintered body is expressed as 0.3 Ra(min)/Ra(max)  0 . 8 , where Ra(min) represents surface roughness in a direction parallel to a grinding direction of a grinder and Ra(max) represents surface roughness in a direction perpendicular to the grinding direction of the grinder.   
     
     
         15 . The surface-covered cubic boron nitride sintered body tool according to  claim 12 , wherein
 the cubic boron nitride sintered body is exposed in a whole portion of the nega-land.   
     
     
         16 . The surface-covered cubic boron nitride sintered body tool according to  claim 15 , wherein
 the nega-land has a width W of 0.05-0.2 mm.   
     
     
         17 . (canceled) 
     
     
         18 . The surface-covered cubic boron nitride sintered body tool according to  claim 11 , wherein
 the cubic boron nitride sintered body is exposed in a whole portion of the nega-land.   
     
     
         19 . The surface-covered cubic boron nitride sintered body tool according to  claim 18 , wherein
 the nega-land has a width W of 0.05-0.2 mm.   
     
     
         20 . The surface-covered cubic boron nitride sintered body tool according to  claim 11 , wherein
 arithmetic mean surface roughness Ra of a portion of the nega-land exposing the cubic boron nitride sintered body is expressed as 0.3≦Ra(min)/Ra(max)≦0.8, where Ra(min) represents surface roughness in a direction parallel to a grinding direction of a grinder and Ra(max) represents surface roughness in a direction perpendicular to the grinding direction of the grinder.   
     
     
         21 . A method of manufacturing a surface-covered cubic boron nitride sintered body tool, comprising the steps of:
 forming a surface covering film with a PVD method on a surface of a tool material having a cutting edge portion of a cubic boron nitride sintered body, said surface covering film includes a nitride or a carbonitride of a compound including at least one element selected from the group consisting of Ti, Cr, Zr, and V and at least one element selected from the group consisting of Al, Si and B, or a nitride or a carbonitride of Ti; and   forming a nega-land to expose the cubic boron nitride sintered body in at least a portion thereof associated with a cutting cross section.   
     
     
         22 . The method according to  claim 21 , further comprising the step of
 honing at least a portion of a periphery of the nega-land after the step of forming said nega-land.