Manufacturing Method of Suspension Spring for Car

Author:  Takezawa; Ichiki; Tadakuma; Tanae; Akiyama
Source:  US Patent 6,346,157
Doc ID:  2002078
Year of Publication:  2002
Abstract:  
A method for manufacturing a coiled spring having a high fatigue strength to be used for example as a suspension spring of a car using a rod of tensile strength 1910 to 2020 N/mm2 and diameter 8 to 17 mm. In a cold coiling step, the rod is formed into a coil. Annealing is then carried out to remove strains having arisen inside the coil during the coiling step. A hot setting step of utilizing surplus heat from the annealing step and applying a predetermined load to the coil to compress it for a predetermined time is then carried out. After that, multi-stage shot peening is carried out on the coil.