工程尺寸驱动原理的完善及其在公差分析中的应用

目前，工程尺寸驱动原理尚未涵盖三维模型中的隐式约束与几何约束，故公差尺素链分析法（GECM）的应用受到一定的限制。为此，本文对工程尺寸驱动原理进行了完善，并建立了面向虚约束模型（VCM）的公差分析方法。首先，分析工程尺寸不可驱动的原因，建立建模参数集可驱动工程尺寸集的充分必要条件；其次，针对工程尺寸不可驱动的模型，提出产品虚约束模型，给出虚约束模型的构建方法，并构造虚约束模型的公差分析算法；最后，通过实例测试，验证本文所提模型的正确性和算法的有效性。

Improvement of Engineering Dimension Driving Principle and Its Application to Tolerance Analysis

Currently, geometrical and implicit constraints cannot be driven with the functional dimension driving theory, which limits the application of the geometrical element chain method (GECM). To solve this problem, this paper presents a modification of the functional dimension driving theory and constructs an algorithm of tolerance analysis oriented to the virtual constraint model (VCM) to extend the application scope of GECM. Firstly, the causes are analyzed for the driving failure of the functional dimensions, and the necessary and sufficient conditions are given for the existence of the mapping relationship. Secondly, the concept of VCM is put forward for the models in which the functional dimension driving principle doesn't work, and the tolerance analysis algorithm of the VCM is constructed. Finally, an example is given to illustrate the validity of the VCM and the effectiveness of the algorithm in this paper.