我厂气门颈部R车削加工是在盘端面精加工后进行的。原采用普通定位模以盘端面倒角和杆端面倒角定位进行加工,如图1所示:加工时、气门的轴向定位精度,直接受气门盘外圆直经,盘端面倒角大小的制约,现以我厂生产的490进气门为例分析如下: 该气门盘外圆直经D=φ41± 0.15。盘厚H=3.52+0.10。如图2所示: 设AA′为盘外圆最大极限尺寸,BB′为盘外圆最小极限尺寸,则AA′=φ41.15, I plant the valve neck R turning is finished in the disk end after finishing. The original use of ordinary positioning mode to chamfering the end face of the disc and the chamfering of the rod end face machining, shown in Figure 1: Machining, the axial positioning accuracy of the valve, directly by the outer diameter of the valve disc straight, chamfering the end face of the disc size Constraints, now I plant the 490 intake valve as an example analysis is as follows: The valve plate through the outer diameter of D = φ41 ± 0.15. Thickness H = 3.52 + 0.10. As shown in Figure 2: Let AA ’be the maximum limit of disk outer circle, BB’ be the minimum limit of disk outer circle, AA ’= φ41.15,