中文摘要：

为支持产品概念设计的多结构方案优选和成本优化，提出了在概念设计阶段进行公差设计的思想。给出了指导概念结构设计的生长型设计过程模型，应用旋量对功能表面间的几何约束进行分析；在公差表示模型的基础上，自动选择基准框架，生成三维公差链并进行设计计算；开发了相应的软件系统支持设计过程。应用实例表明，公差与结构同步设计能有效地减少设计方案的反复修改，提高了设计的效率和质量，对CAD／CAM集成具有重要意义。

英文摘要：

For supporting the multi-structure-scheme selection in conceptual design process and the product cost optimization,the tolerance design was carried out in the conceptual design state. The growth design methodology and its model were presented and used to direct the product structural design. The geometrical constraints were formed between the functional surfaces composing product conceptual structure and analyzed by using screw method. Based on the tolerance representation model, the tolerance reference frame was selected automatically and generated three-dimensional tolerance chain. The software was developed for supporting this design process. The example indicates that the synchronous design approach for 3D tolerance and structure can reduce design modification, improve design efficiency and qualification and have significance for CAD/CAM integration.