正态分布规律下尺寸链设计分析

Design Analysis of Dimensional Chain Based on Normal Distribution Law

为了提供尺寸链评判的量化依据、优化尺寸链关联尺寸的设计、降低零件加工成本,提出了一种新的基于正态分布规律的概率法尺寸链设计方法。通过概率法分析可知尺寸在设计公差范围内的分布规律服从正态分布,推导出在尺寸链中封闭环也服从正态分布,从而得出封闭环在设计要求区间内的概率值,进而评判机械装配中的间隙、干涉等是否具有合理性。结果表明:该尺寸链设计法可根据封闭环在设计要求区间的实际情况以概率值进行量化,从而使尺寸链设计的评判更加具体化;封闭环的区间概率值与尺寸链中的组成环可进行关联,因而对组成环的各零件尺寸进行调整优化,以提高封闭环的区间概率;对封闭环区间概率过低的情况,给出了在尺寸链中增加调整垫的设计方法和原则。

In order to provide a quantitative basis for the dimensional chain assessment,optimize the design of the dimensional chain associated dimensions,and reduce the processing cost,a new probability dimensional chain design method was proposed based on the normal distribution law.Assuming that any size within the design tolerance is normally distributed,It can be known through the analysis of the probability method that the closing link in the dimensional chain is normally distributed,thereby the probability of the closing link within the required interval can be calculated,which can be used to assess whether the clearance or interference in mechanical assembly is reasonable or not.The results show that the dimensional chain design method can be quantified by the probability according to the actual situation of closing link in the required interval,thereby making the dimensional chain design assessment more specific;the probability of the closing link can be associated with the component links in the dimensional chain,then the sizes of the component links can be adjusted and optimized to improve the within-interval probability of the closing link.For cases where the within-interval probability of a closing link is too low,the design method and principle of adding adjusting pads in the dimensional chain are given.