Abstract: To compensate for the shortage of precision in the mechanical assembly process,a product assembly precision modeling based on polychromatic sets theory was proposed,which provided an efficient assembly precision intelligent calculation methods for designers in the initial design stage of product.A set of computer-aided automatic generation process of assembly precision was provided by this model,the assembly constraint matrix,assembly surface features constraint contour relation matrix,assembly tolerances type contour boolean matrix and assembly spatial relationships contour boolean matrix were constructed.The adjacency matrix was used to storage the information in computer.Thus the whole process mapping from part assembly surface feature extraction and feature constraints to assembly whole precision was realized.The model contained the extrinsic constraint conditions of product functional requirements,geometry features,tolerance criteria and tolerance allocation rule,which could illustrate the accuracy and practicality of the model.The effectiveness of model was proved by CNC machine tool feed system application.

Key words: polychromatic sets theory, feed system, tolerance information, representation model, assembly tolerances, small displacement torsor

摘要： 为了弥补在机械装配过程中产品装配精度难以保证的不足,提出一种基于多色集合理论的产品装配精度模型,为设计者在设计阶段提供一种有效的装配精度自动化计算手段。该模型提供了一套计算机辅助装配体装配精度自动生成流程,模型中构建了装配约束关系矩阵、装配特征表面约束围道关系矩阵、装配公差类型围道布尔矩阵及装配空间关系围道布尔矩阵,并采用邻接矩阵的方式对其进行计算机存储,实现了从提取零件装配表面特征及特征约束到装配体整体精度之间的全过程映射。该模型同时包含设计过程中需要考虑的产品功能需求、几何特征、公差准则、公差分配规则等外在约束条件,进一步说明了模型的准确性和实用性。通过该模型在数控机床进给系统的应用验证了模型的有效性。

关键词: 多色集合, 进给系统, 公差信息, 表示模型, 装配公差, 小位移旋量理论