测量锥体螺纹塞规中径,采用间接法,其准确度由测量原理图的参数确定。最普遍的是量针法。在准确度和生产率方面,最完善的是三针法。但这种方法没有考虑到下述情况:测量具有不对称牙型的量规时,它们相对于测量线的分布不一致,这就引起修正量与被测距离 H_2的变化(见图)。实际上,对于α=60°及α=55°的牙型角不对称的和对称的量规,分析表达式与修正值应该彼此不同。 Measuring conical thread plugs diameter, the indirect method, the accuracy of the measurement principle diagram to determine the parameters. The most common is the amount of needle method. In the accuracy and productivity, the most perfect is the three-pin method. However, this method does not take account of the fact that when gauges with asymmetrical teeth are measured, their distributions are not uniform with respect to the measuring line, which causes a change in the amount of correction and measured distance H 2 (see figure). In fact, analytical expressions and correction values ​​should be different from one another for asymmetrical and symmetrical gauges of angle α = 60 ° and α = 55 °.