Shot-peening device and shot-peening method

Abstract

A shot-peening device capable of improving the fatigue strength of a workpiece by applying compressive residual stress to the inside of the workpiece has a hollow housing and a vibration device for vibrating the housing. The housing stores a workpiece and shot therein. The vibration device vibrates the housing with the workpiece and the shot stored therein. Accordingly, the fatigue strength of the workpiece is improved by applying compressive residual stress to the inside of the workpiece.

What is claimed: 
     
         1 . A shot-peening device comprising:
 a hollow housing;   a vibration means operable to vibrate the housing;   a workpiece and shots being stored within the housing; and   the vibration means being operable to vibrate the housing with the workpiece and the shots stored therein.   
     
     
         2 . The shot-peening device according to  claim 1 , wherein the shots are disposed inside the workpiece. 
     
     
         3 . The shot-peening device according to  claim 2 , wherein:
 the workpiece is a compression coil spring; and   the shots have a diameter larger than a pitch of the compression coil spring.   
     
     
         4 . The shot-peening device according to  claim 1 , further comprising:
 a rotating means operable to rotate the housing.   
     
     
         5 . The shot-peening device according to  claim 1 , wherein:
 the workpiece is a compression coil spring;   the shots and the compression coil spring are stored in a compressed state within the housing; and   the vibration means vibrates the housing with the compressed compression coil spring and the shots stored therein.   
     
     
         6 . A shot-peening method comprising:
 providing a shot-peening device according to  claim 1 ;   applying compressive residual stress to the workpiece using the shot-peening device; and   then applying compressive residual stress again to the workpiece to which the compressive residual stress has been applied, using an existing shot-peening device.   
     
     
         7 . A shot-peening method comprising:
 applying compressive residual stress to a workpiece using an existing shot-peening device; and
 then improving surface roughness of the workpiece using the shot-peening device according to  claim 1 .