摘要
多轴数控机床的在机测量会存在冗余运动自由度,由此导致一个测量任务会有多个与之对应的伺服运动方案,而确定最优的伺服运动方案,是保证在机测量性能的前提。针对这一问题,提出一种基于机床功能且面向测量任务的在机测量运动方案创成方法:采用多体系统理论及齐次坐标变换方法对被测对象的几何特征及数控机床的运动形式进行数学解析;建立以被测几何特征为自变量、以机床伺服运动为因变量的函数方程;求解该方程获得所有可能的测量运动方案。在此基础上,通过分析方程解的取值范围,验证所有测量运动方案的功能;考虑到数控机床的结构及伺服特性对测量精度的影响,提出了测量方案性能评价准则,并据此确定最优的测量方案。在某数控成形砂轮磨齿机上进行了齿形偏差的在机测量,试验结果验证了该方法的有效性和可行性。利用该方法确定的最优在机测量方案测量精度高、重复性好。
The multi-axis CNC machine tool may have some redundant freedoms for being used in on-machine measurement（OMM）, which will result in that one measurement task could be done by different servo motion schemes. Thus, how to determine metering schemes to check a workpiece with high accuracy and efficiency is an important problem and also a focus for researchers. To solve this problem, a generation method of task-oriented OMM scheme is proposed. Utilizing multi-body system theory and homogeneous coordinate transformation, geometrical characteristic of workpiece and movements of machine tool are analyzed mathematically. A function relationship between the geometrical characteristic of workpiece as independent variables and motions of machine tool as dependent variables is established. All possible metering schemes are obtained based on the solutions of functional equation and their feasibilities are verified by analyzing the value range of the solution. Considering the influences of the configuration and servo characteristics of CNC machine tool on measuring accuracy, some assessment criterions are presented and so the optimal metering scheme is selected in the end. Finally, the experiment of profile error was carried on a CNC gear forming grinding machine, and the feasibility and efficiency of the methodology has been verified by the experimental resultants. The optimal OMM scheme gained by the method presented in the paper has good characteristic of accuracy and repeatability.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2017年第20期13-19,共7页
Journal of Mechanical Engineering
基金
国家自然科学基金(51375382)
陕西省教育厅产业化培育(2013JC27)
西安理工大学博士创新基金(207-002j02)资助项目
关键词
多轴数控机床
在机测量
方案创成
齿形偏差
multi-axis CNC machine tool
on-machine measurement
scheme generation
gear profile error
