浅谈ASME和ISO几何尺寸公差标准差异

The GD&T Standard Contrast Between ASME Standard and ISO Standard

几何尺寸公差(GD&T,Geometric Dimensioning and Tolerancing)是一种用符号来表达零部件几何尺寸与公差的方法,是一种用来描述零件的尺寸、形状、方位和定位策略等[1]特征的精确的数学语言。目前全球通用的GD&T标准有ASME Y14.5标准和ISO标准。两套标准出发点和设计思路不一样造成两套标准略有差异。准确理解两者的差异,对于设计人员精准设计,工艺人员理解设计图纸,检具工程师检具设计,检测人员检测零件具有十分重要的意义。本文重点选取公差规则、非对称轮廓度、复合公差、可逆要求等四个方面对比两个标准的差异。最后介绍了我国国标在几何尺寸公差方面的现状以及和国际标准的差距。

The GD＆T, short for Geometric Dimensioning and Tolerancing, is a method which is used for expressing the dimension and tolerance for the parts and also a mathematic language which is used for describing the dimension, form, orientation, position and locating strategy for the parts. The most popular GD＆T standards are ASME Y14.5 and ISO standard. The content of the two standards are different to some extent caused by start point and design ideas. It is very important for design engineers, process technician, gage engineers and to have a good understanding during their daily work. Four examples, the tolerance principle, unilateral tolerance, composite tolerance and reciprocity requirement, are specially chosen to make this contrast. At last, the gd＆t GB standards were introduced and a brief contrast was given between GB standards and the advanced international standards.