摘要
针对机床几何误差与零件误差映射关系建模方法并未考虑刀具在加工过程中各个点位的位置偏差与姿态偏差的问题,以三轴机床为研究对象,首先利用多体系统运动学理论,建立机床刀尖点误差与刀轴矢量误差模型。然后利用单基站激光跟踪仪多次测量的方法,结合误差分离算法,辨识得到了机床的21项几何误差项,并对18项与位置有关的误差项进行拟合,构建了完整的典型三轴机床工作空间误差场。最后以凸台宽度、平面度、孔轴线位置度等典型特征,结合加工轨迹,建立起机床几何误差与尺寸误差、形状误差和位置误差的映射关系,并进行了相应的实验验证。实验结果表明:凸台宽度误差与机床刀尖点在该处的几何误差有关,11个点位的凸台宽度误差测量值与计算值相差在5μm以内;“之”字型铣削平面度误差分析要先进行刀具轨迹离散化,然后将刀具圆周离散化,计算刀具圆周含有误差的点,通过点位筛选原则,选择真正属于加工表面的点,对这些点利用最小二乘法计算平面度,平面度误差计算值与测量值相差2μm以内;孔轴线位置度误差分析要考虑钻孔过程中不同位置处刀尖点误差与刀轴姿态误差,以二者为基础构建孔轴线方程,通过代入检测平面的高度以获取相应高度处圆心偏差,孔轴线位置度误差计算值与测量值相差5μm以内。
At present,the modeling method of geometric error and the accuracy of parts does not consider tool’s position deviation and gesture deviation in machining.In order to establish a mapping relationship between geometric error and part error that conforms with machining process and realize the prediction of the part machining error a three-axis machine tool is used as the research object.Firstly,the model of tool position error and tool axis vector error of machine tool are established by using the theory of multi-body system dynamics.Then,the geometric error data of machine tool are identified by using laser tracker and 21 errors of machine tool are obtained,and 18 errors related to position are fitted to build an error space of machine tool.Finally,the typical part features such as part width,flatness,and hole axis position error are selected combined with the moving path of the cutter in machining,and the model between the machine tool geometric error and the part features is established.The accuracy of the model is verified by experiments.The experimental results show that part width error is related to the geometric error of the tool tip,and the differences between measured value and calculated value of part width at 11 points are within 5μm;the zigzag milling flatness error analysis needs to discretize the tool path firstly,then discretize the tool circle and calculate the point error of the tool circle,finally select the points that belong to the machining face and calculate the flatness error by using the least square method with those points,and the difference between the measured value and calculated value of flatness error is within 2μm;the position error of hole axis analysis needs to consider the tool tip error and the tool axis error at different positions during the drilling process,then establish the hole equation with those two,and finally obtain the error of the center of circle in corresponding plane by substituting the height value of the measurement plane into the equation.The difference between measured value and calculated value of the position error of hole axis is within 5μm.
作者
栗世豪
张俊
唐宇阳
尹佳
赵万华
LI Shihao;ZHANG Jun;TANG Yuyang;YIN Jia;ZHAO Wanhua(State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, China)
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2021年第10期50-59,共10页
Journal of Xi'an Jiaotong University
基金
国家重点研发计划资助项目(2018YFB1701901)
西安市科技创新计划资助项目(2019121015KYPT001JC003)。
关键词
几何误差
加工误差
多体系统
geometric error
machining error
multi-body system
