加工尺寸分布对零件合格率和装配合格率的影响

The Inftuence of Dimensional Distribution in Machining on the Parts and Assembly

建立了零件合格率和装配合格率的计算公式 ,定量分析了零件总体平均尺寸与公差中心不重合对零件合格率和装配合格率的影响 ,分析表明总体平均尺寸与公差中心偏离越大 ,零件合格率和装配合格率尤其是零件合格率降低越多。因此 ,用调整方法进行加工时应彻底纠正传统的调整法———加工尺寸为包容尺寸时靠下差 ,为被包容尺寸时靠上差的做法 ,要加强对小样本的检查 ,发现样本平均尺寸偏离零件公差中心时 ,及时进行调整 ,以期提高合格率 。

This paper set up the formulae for computing the pass rates of parts and assembly and quantitatively analyzed the influence of population mean dimension and misalign of talerance center on the pass rates of parts and assembly.It is concluded that the more the deviation between population mean dimension and tolerance centre,the less the pass rates of parts and assembly.Traditional adjustment,bottom deviation is selected when the machined face is female and top deviation is selected when the machined face is male,should be given up.It is recommended that adjustment should be made once sample mean dimension deviates from tolerance center of parts.