发动机气门弹簧、主离合器弹簧,使用一个时期后,其原有的标准自由长度和标准弹力明显下降。大修、三保时一般需要更换或修复弹簧。我们过去修理气门弹簧是先用弹簧扩张机恢复弹簧原来的自由长度,然后在电炉内加热至300～350℃,保温25分钟后,在机油中冷却至室温。修复工艺虽简单,但使用寿命只为新件的1/3。通过实验,我们采用如下新工艺:1.用弹簧扩张工具扩簧,恢复弹簧长度,并比原长度长出5％。 Engine valve spring, the main clutch spring, after a period of use, its original standard free length and standard elasticity decreased significantly. Overhaul, three security generally need to replace or repair the spring. We used to repair the valve spring is to use the spring expansion machine to restore the original spring free length, and then heated to 300 ~ 350 ℃ in the electric furnace, incubated for 25 minutes, cooled to room temperature in the oil. Although the repair process is simple, but the service life of only one-third of the new piece. Through experiments, we use the following new technology: 1. Expand the spring with a spring expansion tool to restore the spring length, and longer than the original length of 5%.