无基准的孔组位置度三坐标测量模型

CMM Model of Hole Group Position without Datum

零件上孔组位置度的标注有时会出现无基准的情况,这虽然符合国标的要求,但却往往引起测量人员与设计人员之间的分歧,导致评价不够准确。文章在最小二乘法的基础上,给出了一种孔组位置度的理论计算模型,然后以某安装支架为例,用三坐标测量机进行了实际的测量和评价,并与PC-DMIS软件的结果进行了对比,验证了该种无基准孔组位置度测量评价模型的有效性。

The marking of the hole group position degree on the part sometimes appears without a reference,which is in accordance with the requirements of GB/T,but often causes disagreement between the measurer and the designer,resulting in less accurate evaluation.In this paper,a theoretical calculation model of hole group position degree is given based on the least squares method,and then a mounting bracket is used as an example to carry out the actual measurement and evaluation with a CMM,and the results are compared with those of PC-DMIS software to verify the validity of this datum-free hole group position degree measurement and evaluation model.