Abstract: The invention relates to a method for manufacturing a coil spring and for determining a propelling condition for a shot medium. In a case where it is confirmed that the coating film remains in a third step, at least one or more of conditions of the shot peening treatment including a propelling speed of the shot medium, a propelling time of the shot medium, a material of the shot medium, and an average particle diameter of the shot medium are changed and the second step and the third step are repeated until the coating film does not remain. In a case where it is confirmed that the coating film does not remain in the third step, the condition of the shot peening treatment in the second step in which the coil spring is obtained with no remaining coating film is determined as the propelling condition for the shot medium.

Abstract: A coil spring jig includes a spring support portion where one end of a coil spring is capable of being placed, a plurality of displacement regulating portions extending along an axis of the coil spring from the spring support portion with the coil spring supported by the spring support portion as a reference, capable of abutting against an outer peripheral surface of the coil spring, and regulating displacement of the coil spring in a radial direction of the coil spring, and a lid portion supported by the displacement regulating portions and capable of keeping the coil spring in a compressed state by sandwiching the coil spring together with the spring support portion.

Abstract: In a case where the coating film is confirmed to remain in a third step, at least one or more of conditions of the shot peening treatment including a propelling speed of the shot medium, a propelling time of the shot medium, a material of the shot medium, and an average particle diameter of the shot medium are changed and the second step and the third step are repeated until the coating film does not remain In a case where the coating film is not confirmed to remain in the third step, the condition of the shot peening treatment in the second step in which the coil spring is obtained with no remaining coating film is determined as the propelling condition for the shot medium.