基于模糊故障树的数控龙门铣床加工误差分析与试验

Analysis and Experimental on Mismachining Tolerance of CNC Gantry Milling Machine Based on Fuzzy Fault Tree

针对数控龙门铣床加工中出现的平面度误差问题进行研究与改进,分析工艺系统因素产生的误差,建立加工平面误差的模糊故障树,通过下行法对其进行简化分析,定性分析影响加工平面度误差的最小割集,运用模糊隶属函数定量分析顶事件的发生概率及底事件的发生概率重要度,确定主要因素为工作台形位误差、定位元件误差、热变形等。使用激光测量技术对安装的工作台平面进行矩形布点测量,根据采集数据建立基于最小二乘法的数学模型,运用Matlab软件定性分析平面度的评定,并对超差区域进行改进,最终实现了机床装配与使用要求。

In order to study and improve the flatness error in CNC gantry milling machine processing.Influencing factors of flatness error caused by machining process system are studied and analyzed.Establish a fuzzy fault tree about the error of the machining plane.Using Fussell’s algorithm to simplify it, Minimum cut sets can be obtained through qualitative analysis.The probability of top events and the importance of bottom events are analyzed by the membership functions of fuzzy numbers. The results show that: The main influencing factors are table shape and position error, positioning element error, thermal deformation and so on. Using laser measurement technology to measure the installed worktable plane through a rectangular path.According to the collected data, a mathematical model of least squares method is established. And improve the large deviation area. Finally, the requirements of machine tool assembly and manufacturing are realized.