传统的公差设计大都是基于加工成本最优进行的,对质量方面的考虑较少,而系统基于离散变量围绕装配成功率研究公差稳健设计的论文还鲜见报道，本文旨在探讨基于离散变量的公差稳健设计方法，然后用实例证明该方法的可行性。 　　　本文先讲诉了选题的目的与意义，综述了国内外学者围绕离散变量、公差稳健设计及装配成功率的研究现状，给出了本文的研究目标、内容及技术路线。然后探讨了产品的稳健性,阐述了公差设计的内容,对离散公差设计模型进行分析研究，接着应用试验设计方法进行基于总成本的离散公差稳健设计和基于装配成功率的离散公差稳健设计。 　　　(1)基于总成本的离散公差稳健设计。以刮板输送机舌板上轴孔组的尺寸链为研究对象，以装配成功率为约束，以尺寸链中各组成环和封闭环尺寸公差水平值所相对应的总成本（总成本包括生产成本，社会使用成本，市场推广成本）最小化为目标，对刮板输送机舌板上轴孔组的尺寸链进行优化设计。 (2)基于装配成功率的离散公差稳健设计。以一个箱体上轴孔组的尺寸链为研究对象，以预定的装配成功率为约束，使尺寸链中各组成环和封闭环尺寸公差水平值所相对应的生产成本最小，然后在产品的生产成本增幅较小的情况下，使产品的装配成功率有显著地提高。

The traditional tolerance design are mostly carried out based on the optimal processing cost,less consideration of quality, and research paper of robust tolerance design based on discrete variable around assembly success probability.This paper aims to explore the method of robust tolerance design based on discrete variable,and an example is given to illustrate the method. 　　　This paper talks about the purpose and significance of the project,and then summarizes research status of discrete variable,robust tolerance design and assembly success probability,and then gives research objective，research contents and technology roadmap of this article.This paper discusses the the robustness of the product, describes the contents of tolerance design,analyse the model of discrete tolerance design,and then with DOE of a robust discrete tolerance design based on total cos and a robust discrete tolerance design based on assembly yield. (1)A robust discrete tolerance design based on total cost.Taking thedimension chain of a scraper conveyor board’s shaft hole group for research object,assembly yield for constraint, and taking the minimum total cost produced by size tolerance level value of the dimension chain for objective, the dimension chain is optimized. 　　　(2)A robust discrete tolerance design based on assembly yield.Taking the dimension chain of a box’s shaft hole group for research object,and preconcerted assembly yield for constraint,to minimize production cost produced by size tolerance level value of the dimension chain.Then as the production cost decrease a little,the success rate of the product assembly will have significantly improved.