| 摘要 |
<p>PURPOSE:To manufacture an automobile suspension spring or an engine valve spring excellent in fatigue strength by disposing a tempered coiled spring in a state where both ends of the spring are connected into a coil, sending a high- frequency electric current to the coil to apply rapid heating to the surface layer of the coiled spring, rapidly cooling the above surface layer, and further setting the above. CONSTITUTION:Both ends of an automobile suspension spring or an engine valve spring composed of an oil tempered wire of Cr-V steel are connected, which is inserted into a coil made of metal. A high-frequency electric current of 2kHz-30MHz frequency is sent to both ends of the above coil and an induced current is impressed on the surface layer part of the spring to apply rapid heating, and then, rapid cooling is applied to the surface layer part of the spring to carry out hardening. Subsequently, after subjecting the above surface to shot peening or without applying shot peening, setting is carried out, e.g., at 180 deg.C. By this method, the automobile suspension spring or engine valve spring excellent in fatigue strength can be manufactured.</p> |
