2001 年 2001 巻 46 号 p. 1-6
High fatigue strength of valve springs for automobiles is intensely required for weight reduction and high velocity revolution. For this subject, springs have been developed in terms of both chemicals in the material and wire processing sides. In this paper the high fatigue-proof spring was developed using the high Si oil tempered wires with high heat resistance by increased Si. As results, the developed valve spring exhibits the good performance. The experimental results are as follows; 1) Results of springs with shot speening Between developed spring and control spring iSWOSC-VTS j, there was no difference in the hardness distribution and residual stress distribution. Developed spring durability and sag resistance are improved 10% and 6% respectively, as compared with the control spring. 2) Results of springs with nitriding and shot peening Developed spring with high temperature nitriding and hard shot peening achieved big improvement of 25% in the durability and 6% in the sag resistance compared with the control spring with low temperature nitriding and normal shot peening.