Method for Manufacturing Mechanical Part Excellent in Rolling Fatigue Life

Abstract

Disclosed is a method for producing a mechanical part superior in rolling fatigue life. The mechanical part includes a rolling portion for a rolling element to roll along an inner diameter surface of an annular workpiece material subjected to cold forging. The method includes performing cold forging by applying a hydrostatic stress to the inner diameter surface of the annular workpiece material on which the rolling portion is to be formed, thereby forming the rolling portion on the inner diameter surface of the annular workpiece material for the rolling element to roll therealong and increasing an inner diameter of the annular workpiece material other than the rolling portion, so as to provide an annular mechanical part including the rolling portion superior in rolling fatigue life.

1 . A method for producing a mechanical part superior in rolling fatigue life, wherein the mechanical part comprises a rolling portion for a rolling element to roll along an inner diameter surface of an annular workpiece material subjected to cold forging, wherein the method comprises the step of:
 performing cold forging by applying a hydrostatic stress to the inner diameter surface of the annular workpiece material on which the rolling portion is to be formed, thereby forming the rolling portion on the inner diameter surface of the annular workpiece material for the rolling element to roll therealong and increasing an inner diameter of the annular workpiece material other than the rolling portion, so as to provide an annular mechanical part comprising the rolling portion superior in rolling fatigue life.   
     
     
         2 . The method according to  claim 1 , wherein the annular workpiece material to be subjected to cold forging is a steel pipe. 
     
     
         3 . The method according to  claim 1 , wherein the annular workpiece material to be subjected to cold forging is a hot forged ring. 
     
     
         4 . The method according to any  claim 1 , wherein the hydrostatic stress is at least 1000 MPa. 
     
     
         5 . The method according to  claim 2 , wherein the hydrostatic stress is at least 1000 MPa. 
     
     
         6 . The method according to  claim 3 , wherein the hydrostatic stress is at least 1000 MPa.