氮碳共渗后气门杆部直线度与锥面跳动超差原因分析

Cause Analysis on Out of Tolerance of Stem Straightness and Cone Runout of Valve after Nitrocarburizing

发动机气门在氮碳共渗后出现气门杆部直线度和锥面跳动超差,比例高达20%。试验结果表明:气门杆部弯曲或焊接后错移大,使得磨削加工时产生校直应力,之后去应力退火不充分会造成杆部直线度超差。气门锥面跳动超差则是由于杆部直线度超差以及圆弧加工或锥面磨削应力大造成的。并提出了改进措施。

The stem straightness and cone runout of engine valves were out of tolerance after nitrocarburizing,accounting for as high as 20%.The results showed that the large displacement of the valve stem after bending or welding would produce straightening stress during grinding,and the insufficient stress relief annealing would lead to the out of tolerance of the straightness.The out of tolerance of cone runout was caused by the out of tolerance of stem straightness and the stress remained after valve under head turning or cone grinding.The improvement measures were put forward.