基准标注导致测量基准不确定的解决方法

Solution of Measurement Mark Change Caused by Datum Mark

由基本立体元素组成的双锥零件的尺寸既具有控制零件大小,又具有控制零件形状的双重特性。双锥零件的常规方法以实际端面为基准进行测量,由于实际端面往往与设计基准不重合,造成了较大的测量误差。提出双锥零件的测量基准相对于理想基准的位置按"最小条件"来确定的方法。该方法测量基准的位置不变,基准误差为0,有效地解决了双锥零件特性尺寸测量误差的问题。

The size of double cone parts composed by the basic three-dimensional element not only has a control part size, but also has double characteristics of control part shape. Measurement of double cone parts in conventional method is processed with respect to the actual end face as datum mark. Since the actual end face sometimes is not in superposition with designed mark, quite big measuring error is caused. The method was put forward as the measurement mark of double cone parts relative to location of ideal mark should be determined according to the method of ＂minimum condition＂. Thus, the measurement mark location is invariant with this method, and the mark error is zero, which effectively solves the problem of measuring error in double cone part characteristic size.