METHOD FOR DETERMINING PROPELLING CONDITION FOR SHOT MEDIA, AND METHOD FOR MANUFACTURING COIL SPRING

摘要

Provided is a method for determining a propelling condition for a shot media, comprising: a first step of forming a coating film (36) on the surface of a coil spring (30); a second step of performing a shot peening treatment of propelling a shot media (42) onto a coil spring (30a) with the coating film formed thereon; and a third step of determining whether or not the coating film remains on a coil spring (30b) having been subjected to the shot peening treatment. When it is determined in the third step that the coating film remains, conditions of the shot peening treatment including at least propelling speed, propelling time period, material, and the average particle diameter of the shot media are varied and the second step and the third step are repeated until the coating film does not remain. When it is determined in the third step that the coating film does not remain, the conditions of the shot peening treatment in the second step under which the coil spring with no coating film remaining has been obtained are determined as the propelling conditions for the shot media.