随着机床、内燃机技术指标要求的提高,必须大大提高机床和仪器主要部件和零件的制造精度。苏联最近颁布了一系列标准,规定了提高内尺寸的测量精度。ΓOCT11472-65“一级精度公差”规定制造轴和孔一类产品的极限偏差分八个精度等级。对于尺寸为30—50毫米的二级标准规定孔的极限 As machine tools, internal combustion engine specifications to improve the requirements, we must greatly enhance the machine tools and equipment main components and parts of the manufacturing accuracy. The Soviet Union has recently promulgated a series of standards that set out to improve the measurement accuracy of internal dimensions. ΓOCT11472-65 “a precision tolerance ” provides the manufacture of shaft and hole a product of the standard deviation of eight degrees of accuracy. For the secondary standard size 30-50 mm hole limit