基于最短路径的复杂机械产品装配过程质量控制点公差带在线优化方法

Research on Online Tolerance Optimization for Complex Mechanical Products Assembly Process Based on Shortest Path

为提高复杂机械产品的装配精度和装配质量稳定性,提出一种基于最短路径的复杂机械产品装配过程质量控制点公差带在线优化方法。对关键工序的质量控制点公差带进行细粒度划分;从装配精度角度出发,引入田口工序能力指数构建质量损失—公差函数;综合考虑装配过程中两种作业(基本作业和辅助作业)类型的时间调整损失,建立装配时间调整费用—公差函数;在上述两函数的基础上,通过加权聚类建立装配损失—公差函数模型,以描述质量控制点的总损失与公差的关系;构建基于最短路径的公差带在线优化模型,将装配损失—公差函数作为权函数,以最小损失为目标进行搜索,实现对后续质量控制点公差带的在线优化。以某型发动机缸盖螺栓拧紧过程为应用实例,验证了上述方法的可行性和有效性。

To improve assembly precision and assembly quality stability for complex mechanical products,an online tolerance optimization approach based on shortest path is put forward.The tolerance zone of the key process is divided into several zones with fine granularity;the assembly cost-tolerance function is structured from the prospect of the assembly precision;considering the time adjustment cost of the two different operations（basic operations and auxiliary operations） in the assembly process,the assembly time cost-function is established;based on the two functions,the assembly cost-tolerance function model is put forward by the means of the weighted clustering to describe the relationship between the assembly tolerance and the cost.The online tolerance optimization model based on shortest path is established,and the assembly cost-tolerance function is defined as the weight function to realize the online tolerance optimization by searching the online tolerance optimization model for gaining the minimum assembly cost.An example of online tolerance optimization model in the assembly process of the engine cylinder head is given to demonstrate the feasibility and effectiveness of this method.