小型圧縮コイルばねの温間へたりに関する共同研究報告

抄録

This committee aimed to provide technical information (commentary) that can predict high-temperature spring set (residual shearing strain “γ value”) when designing and manufacturing compact coil springs for engine valve. The committee was divided into “Literature WG (Working Group)” and “Test WG”, and Literature WG gathered and organized technical literatures related to “γ value” at higher temperature. Test WG used test springs of which the wire diameter φ 1.0, 4.0 mm of 3 steel types (SWP - A, SWOSC - V, SUS 304 - WPB), including with processing or without processing(non) of shot peening and setting. Test temperature was set from 100 to 450 ℃, clamping time was set from 24 to 312 h, and the high-temperature spring set (calculated to “γ value”) was measured after clamping test at higher temperature. Various data of “γ value” obtained with less variance, and the influence of loaded stress, temperature and time on “γ value” with reasonable tendency for each test element. We confirmed that the obtained data generally agreed with various data in past technical literatures. So, we think that the obtained data will be able to provide useful database. However, in this activity, we cannot reconsider using the obtained data about highly practical calculation formula to express the difference at the temperature range (low temperature: around 200 ℃, high temperature: around 350 ℃). In the future, it is necessary to verify the high-temperature spring set mechanism at higher temperature and re-examination of highly practical calculation formulas.