Rolling/sliding part, rolling bearing, cam follower, and method of modificating surface of rolling/sliding part

Abstract

The invention provides a cam follower having an outer ring which is used in a state where the cam follower comes into sliding contact or rolling contact with a mating part. The outer ring is configured such that the hardness of a surface layer portion existing between the surface and at least 3 μm below the surface is Hv 780 to 900, and the hardness of an internal surface portion existing at a depth of 10 μm or more from the surface is lower than the hardness of the surface layer portion and less than Hv 780. Such hardness can be obtained by performing soft shot blasting or flow barrel processing on a surface layer portion of a base material to be the outer ring.

1 . A rolling/sliding part used in a state where the rolling/sliding part comes into sliding contact or rolling contact with a mating part, 
 wherein hardness of a surface layer portion existing between a surface thereof and 3 μm below the surface is Hv 780 to 900, and hardness of an internal surface portion existing at a depth or 10 μm or more from the surface is lower than the hardness of the surface layer portion and less than Hv 780.    
   
   
       2 . The rolling/sliding part according to  claim 1 , wherein the hardness of the internal surface portion is Hv 60 or more lower than the hardness of the surface layer portion.  
   
   
       3 . The rolling/sliding part according to  claim 1 , wherein maximum compressive residual stress of the surface layer portion is 800 MPa or more and maximum compressive residual stress of the internal layer portion is 300 MPa or less.  
   
   
       4 . The rolling/sliding part according to  claim 1 , wherein the roughness Ra of the surface of the surface layer portion is 0.15 μm or less.  
   
   
       5 . A bearing comprising: 
 a bearing ring constituted by the rolling/sliding part according to  claim 1;  and    a rolling element contacting the bearing ring, the rolling element being constituted by the rolling/sliding part according to  claim 1 .    
   
   
       6 . A cam follower comprising: 
 a rotatable outer ring which comes into rolling contact with a cam, the outer ring being constituted by the rolling/sliding part according to  claim 1 .    
   
   
       7 . A method of modificating a surface of a rolling/sliding part used in a state where the rolling/sliding part comes into sliding contact or rolling contact with a mating parts, the method comprising: 
 performing shot-blasting or barrel processing which has an effect on hardness of only a surface layer portion existing at a depth of, at a maximum, 10 μm from the surface of a base material to be the rolling/sliding part; and    repeating the processing until it is confirmed that, when Vickers hardness measurement is performed on the base material after the processing, hardness A measured under a load of 0.1 N becomes Hv 780 to 900, and hardness B measured under a load of 1 N becomes lower than the hardness A and less than Hv 780.