Method for enhancing fatigue strength of gear using shotpeening

Abstract

Disclosed is a method for enhancing fatigue strength of a gear by producing compressive residual stress on a gear surface using shot peening. In the method according to the present invention, a plurality of shot balls are projected in a direction parallel to a straight line connecting a contact point of a root circle and an involute curve of a gear tooth to be subjected to the peening to a contact point of a tooth face circle and an involute curve of a gear tooth adjacent to the gear tooth to be subjected to the peening, and particularly a direction forming an angle of 0° to 15° relative to the straight line by use of high-pressure air.

What is claimed is:  
     
         1 . A method for enhancing fatigue strength of a gear using shot peening which produces compressive residual stress on a gear surface by projecting a plurality of shot balls onto the gear surface by use of high-pressure air, in which: 
 the plurality of shot balls are projected in a direction parallel to a straight line connecting a contact point of a root circle and an involute curve of a gear tooth to be subjected to the peening to a contact point of a tooth face circle and an involute curve of a gear tooth adjacent to the gear tooth to be subjected to the peening.    
     
     
         2 . A method as recited in  claim 1 , wherein the direction of projection of the shot balls forms an angle of 0°to 15°relative to the straight line.