【摘要】 机床专用夹具的定位精度决定着夹具的设计精度，从而影响零件的加工精度.不同的定位方案，其定位误差的分析和计算方法各异.以轴套类零件加工键槽为例，对平面定位、V形块定位及定位销(心轴)定位3种定位方式的定位误差进行比较分析和计算.研究发现：相比于其他两种定位方式，V形块定位方式的定位误差能够同时满足键槽尺寸精度、对称度公差等加工精度的要求.在此基础上，提出合理选择夹具的定位基准、正确设计工序基准、优化定位元件的结构和位置等建议，从而确定最优定位方案.更多还原

【Abstract】 The positioning accuracy of the special fixture for machine tools determines the design accuracy of the fixture and thus affects the machining accuracy of the parts. The analysis and calculation methods of positioning errors vary with different positioning schemes. Taking the machining of keyway of bushings as an example, we compared, analyzed and calculated the positioning errors of three positioning methods, namely, plane positioning, V-block positioning and positioning pin(mandrel) positioning. It was found that compared with the other two positioning methods, the positioning error of V-block positioning method could meet the requirements of keyway dimensional accuracy, symmetry tolerance and other machining accuracy. On the basis of this, we proposed the optimal positioning solution by reasonably selecting the positioning datum of the fixture, correctly designing the process datum, and optimizing the structure and position of the positioning elements, so as to determine the optimal positioning scheme.更多还原