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螺丝、丝锥和螺丝铣刀的中径一般多采用三计量法进行测量,主要是由于这种方法具有相当高的效率和准确度。 TOCT2475—44和检定规程45—48对于新制的和处于使用中的三针所规定的公差是一样的,都是按制造精度(对名义值的偏差大小)分成两个级别:0级和1级。按照检定规程45—48的规定,各主管检定机构每月都不得不大量地报廢许多完全还适用的三针(当然其中也有些是不适用的),因为:即或三针直径超出允许偏差很小(即或0.0003毫米时),也得形式主义地加以报廢,
The diameters of screws, taps and screw mills are generally measured using the three-metrology method, mainly due to the rather high efficiency and accuracy of this method. TOCT2475-44 and verification procedures 45-48 are the same for the new and in use three-pin tolerances and are divided into two levels based on manufacturing accuracy (deviation from nominal value): level 0 and level 1 . In accordance with the provisions of test procedures 45-48, each of the competent test institutes has to scrap a large number of completely applicable three needles (and of course some of them are not applicable) every month because: either the three-needle diameter exceeds the allowable deviation Very small (or 0.0003 millimeters), also have to be scrapped formalism,