Method of producing a plate spring

Abstract

A method of producing a plate spring is disclosed which allows one to adjust the load-displacement characteristics thereof to a desired degree. The method includes stamping slits and a small diameter hole from a disk-shaped plate member, and forming the plate spring into a cone shape. Shot-peening is then performed on a resilient portion of the plate spring that retains a flat cone shape in the free state. Furthermore, shot-peening is performed on only a portion of the resilient portion and not on the entire surface of the plate spring.

What is claimed is:  
     
         1 . A method of producing a plate spring, comprising the steps of: 
 preparing a plate spring that includes an annular resilient portion; and    applying compression residual stress to a portion of the resilient portion.    
     
     
         2 . The method of producing a plate spring set forth in  claim 1 , wherein shot-peening is performed in order to apply compression residual stress to the resilient portion.  
     
     
         3 . The method of producing a plate spring set forth in  claim 1 , wherein compression residual stress is applied to at least one surface of the resilient portion.  
     
     
         4 . The method of producing a plate spring set forth in  claim 1 , wherein the compression residual stress is applied by means of shot-peening to between about 5% and about 95% of the surface area of the resilient portion.  
     
     
         5 . The method of producing a plate spring set forth in  claim 1 , wherein the compression residual stress is applied by means of shot-peening to about 20% of the resilient portion in a thickness direction.  
     
     
         6 . The method of producing a plate spring set forth in  claim 1 , wherein the size of the compression residual stress to be applied to the resilient portion is between about 200 MPa to about 1500 MPa.  
     
     
         7 . A method of producing a plate spring, comprising the steps of: 
 preparing a plate spring that includes an annular resilient portion;    applying a first compression residual stress to the entire resilient portion; and    applying a higher second compression residual stress to a portion of the resilient portion.