在车床上加工零件时,目前还多用游标尺进行停车测量,这不仅浪费时间,多消耗电能,而且由于游标尺测量力很难掌握,测量不准。这主要是由于游标尺的量脚是平行的,测量力会转动游标,所以测量力不同其测量结果也有变化,同时更不能在工件转动下进行测量。戟形游标尺则没有这些弊病,其原理如图1所示。圆外一点P,向圆O作两条切线PA、PB,若两条切线的夹角∠APB=60°,则OP与圆相交于C点,则OC=PC,即PC为圆的半径。 In the lathe machining parts, the current use of vernier ruler parking measurement, which not only a waste of time, more power consumption, but also difficult to grasp because vernier ruler measurement, measurement is not allowed. This is mainly due to the feet of the vernier feet are parallel, the measuring force will rotate the vernier, so the measurement results vary with different measuring forces, and even less can be measured under the rotation of the workpiece. The halberd vernier ruler does not have these disadvantages, its principle is shown as in Fig. A point outside the circle P, to the circle O for the two tangent PA, PB, if the angle between the two tangent ∠ APB = 60 °, the intersection of OP and the circle at the C point, then OC = PC, PC is the radius of the circle.