关键词: 底盘整体合装；合装成功率；尺寸链；形位公差；正态分布；贝叶斯定理

Abstract: Chassis assembly is a key part of vehicle assembly, and the form and position tolerance of the assembled parts determines the success rate and cost of assembly. This paper first describes the physical model of assembly error probability, then abstracts it into a suitably simplified assembly mathematical model by using dimension chain theory, and deduces the formula and calculates the probability of assembly success rate. Finally, the theoretical 99.986% probability of success is obtained under the conditions of tolerance and precision requirements of related tooling equipment, which is larger than the actual value. After analysis, the model is moderately simplified and the difference meets the expectation with assumed conditions. The model has been widely used in a number of standardized multi-platform vehicle hybrid assembly lines.

Key words: Integrated chassis assembly; Success probability of assembly; Dimension chain; Tolerance of form and position; Normal distribution; Bayes' theorem