Abstract: Aiming at the problem that the present assembly tolerance model could not represent information of assembly positioning joints completely,the relationship between parts positioning feature and assembly positioning joints was investigated.To correct conventional assembly tolerance math model,the fit modes of assembly positioning joints were classified,and the constraints of different fits on parts'degree of freedom were represented with victor equation and inequality.The tolerance information of auxiliary joints could be expressed with obtained victor equation and inequality,which could be used to improve conventional mathematical model of assembly tolerance.An example was given to illustrate the application of the proposed model in tolerance analysis.

Key words: mathematical model, degreed of freedom, assembly tolerance, assembly joints, fit mode

摘要： 针对现有的装配公差数学模型不能完全表达装配定位接点对零件约束的问题,研究零件定位特征与装配定位接点之间的关系。将装配定位接点的配合类型进行归纳和分类,并以向量方程/不等式的方式表示辅助接点上各种配合对零件运动自由度的约束。得到的向量方程/不等式可以表达辅助接点的几何及公差信息,并用于修正一般的装配公差模型。最后通过该方法在公差分析中的应用实例验证了所提方法的有效性。

关键词: 数学模型, 自由度, 装配公差, 装配定位接点, 配合类型