研究了平面定位情况下的夹具定位误差通用分析方法。将加工表面、工序基准、定位基准和定位元件等决定定位误差的四个要素用直线、圆、圆弧和点等几何要素表示,并将四个要素之间的位置及其变动关系用平面连杆机构模型等价表示。通过研究采用机构的结构参数表示工件-夹具系统的所有工序信息及其内在联系的方法,建立了工件和夹具定位元件接触副与机构构件之间的映射关系,以及尺寸和形位公差的机构构件和运动副表示方法,从而实现了定位误差计算模型的自动建立。利用机构误差概率分析方法计算了夹具平面定位情况下的定位误差。
General analysis method of fixture positioning error in planar positioning process was studied.There were four elements related to fixture positioning error in workpiece-fixture system,i.e.machining surface,process datum,positioning datum and locators,which could be indicated by four planar geometry elements:line segment,circle,arc and point.Position of the four elements and the position variation among them were denoted by equivalent planar link mechanism model.All sequence information and interrelationships among them of workpiece-fixture system were represented by structure parameter of link mechanism.Mapping rules from contact pairs to mechanism components were established,and the expression method of mechanism components and kinematic pairs were put forward.According to the rules mentioned above,the positioning error computation model was established automatically.Finally,the positioning error in planar positioning process was calculated by mechanism error probabilistic analysis.