机械装配偏差源及其偏差传递机理分析

Mechanism Analysis of Deviation Sourcing and Propagation for Mechanical Assembly

产品装配偏差源和偏差传递机理分析,是装配精度预测的前项工作。综合影响装配功能的尺寸和形位精度、装夹定位精度信息,将刚性零件装配的偏差源分为几何位置偏差、几何形状偏差和装配位置偏差三类;进一步建立面向三类偏差源统一表达和评价的多元统计学模型,及其相对装配功能的正负累积性判断方法。基于偏差源统一表达,分析偏差在零件间、零件内两特征间的偏差传递和相互作用,提出偏差传递的三种偏差流;根据装配过程中是否存在装配间隙,将偏差流分为连续流和断续流两种。基于偏差有向图,对三种偏差流和配合偏差流进行表达;并建立面向整个产品偏差传递及装配功能表达的装配偏差有向图模型。结合某航天器装配为例,验证偏差源表达和偏差传递模型的有效性。

For mechanical precision predicting,mechanism of deviation sourcing and propagation for rigid part assembly is discussed.Considering dimension and geometric precision,and part situation precision,the deviation source that affects assembly precision or accuracy is clustered into three types： deviation of geometric location and orientation,variation of geometric form and deviation of part location and orientation.Unified statistical model with deviation evaluation for these three kinds of deviation source are built,and plus-minus influence factor of deviation source referring to functional requirement is calculated.In addition,mechanism of deviation propagation between two mating surfaces or key characteristics is discussed.Three deviation propagating types are proposed and intermittent and continuous propagation model according to mating status are particularly built.Based on the directed graph representation for deviation,the directed graph for deviation propagation between two mating surfaces or key characteristics are built,and directed graph modeling for whole assembly is discussed.Finally,an example with deviation sourcing and propagation is introduced to verify the effectiveness of each model.