工艺过程统计分析中■—R图的修正

■—R Graph Modification in Statistic Analysis of Technological Process

对目前常用的按3σ准则建立的—R图进行了分析,指出其存在的问题,得出样本极差 R 的概率分布是非对称分布,并运用管理水平法则给出了新的 R 图控制线。

An analysis is made of ■—R graph established on per 3σcriterion and frequently used at the present time.The paper points out the existence of problems due to the mentioned situation, and also draws the conclusion that the possibilities distribution of the sampled polar difference R is of non-symmetry,with the management level law being used to propose a new kind of R- graph's controlling line.