SURFACE TREATMENT METHOD OF COIL SPRING

摘要

PURPOSE: A heat treatment method for a coil spring is provided to implement a first shot peening and a second stress shot peening on the coil spring of which the surface temperature is maintained to be certain degrees, thereby deeply forming the depth of compressive residual stress on a product. CONSTITUTION: A heat treatment method for a coil spring includes: a step(S1) of passing the coil spring through a furnace of which the temperature is maintained to be certain degrees in order to raise the temperature of the coil spring to the certain degrees, and then passing the coil spring through a tempering furnace in order to temper the coil spring; a step(S3) of implementing a first shot peening on the coil spring inside a first shot peening machine for a certain time; a step(S4) of compressing the coil spring inside a second shot peening machine at a certain external pressure; and a step(S5) of implementing a second shot peening on the compressed coil spring inside the second shot peening machine for a certain time. [Reference numerals] (AA) Material inspection and filling; (BB) Heating; (CC) Forming; (DD) Tempering; (EE) Pretreatment; (FF) Coating; (GG) Load test; (HH) Marking; (II) Inspection; (JJ) Shipment; (S1) Heat treatment and tempering; (S2) First setting; (S3) First warm shot peening; (S4) Second setting; (S5) Second compressive shot peening