加热工艺对少片簧疲劳强度的影响及改进措施

针对轻量化后的少片簧在可靠性试验过程中存在早期疲劳断裂的现象,通过分析轻量化少片簧故障件,确认弹簧断裂的主要原因是少片簧相比多片簧工艺上增加了中频感应加热和轧制工艺,加热温度、保温时间不受控制,弹簧钢表面存在全脱碳层,导致弹簧断裂。热处理试验结果显示,使用50CrVA,可确保保温时间控制在9min以内,弹簧钢具有良好的脱碳层深度,且脱碳层深度随着轧制中频感应加热温度升高、保温时间延长而加深。根据以上结论,将弹簧材料由60Si_2Mn调整为50CrVA,增加中频感应加热温控装置,提高工艺命中率。通过对改进前后的材料进行对比试验,结果表明,改进后台架和路试疲劳寿命都有显著提升。

Effect of Heating Technology On Fatigue Strength of Parabolic Spring and Improvement Measures

The light weight parabolic failure spring was analyzed.It is confirmed that the reason for the spring failure is the increase of medium frequency induction heating and roller milling in the process of parabolic spring compare with multiple-leaf spring on technological,and the heating temperature and holding time are uncontrolled.There is the decarburization layer on spring steel surface,which lead to the breakage of spring.The results of heat treatment test show that the holding time can be controlled within 9 minutes by using 50CrVA,and the spring steel has good decarburization depth.The decarburization depth increases with the increase of medium frequency induction heating temperature and the extension of holding time.According to the above conclusions,the spring material is adjusted from 60Si2Mn to 50CrVA,and the medium frequency induction heating temperature control device is added to improve the hit rate of the process.The results show that the fatigue life of the bench and road test has been significantly improved.