测量工件(图1)上孔的位置,采用间接测量较为方便。过圆筒中心O与孔中心O_1作直角三角形OdO_1(图2),令∠O_1Od为θ,由勾股定理可知:l~2=o_1d~2+od~2,……………(1) tg~θ=o_1d/od,…………… (2)这样,测定的方法只是求od与o_1d(图3),D与D＇可直接测量, Measurement of the workpiece (Figure 1) on the location of the hole, indirect measurement is more convenient. Through the cylinder center O and hole center O_1 right-angled triangle OdO_1 (Figure 2), so ∠O_1Od is θ, the Pythagorean theorem shows: l ~ 2 = o_1d ~ 2 + od ~ 2, tg ~ θ = o_1d / od, ............... (2) In this way, the determination method is only seeking od and o_1d (Figure 3), D and D ’can be measured directly,