在万工显上,采用影像法测量表征外螺纹精度的诸参数时,中央显微镜的立柱应倾斜一个角度(以下称为螺旋升角),以使得由光源投射来的光线不被螺纹的螺旋面挡住。螺旋升角ω与螺纹中径d_2和导程T的关系式为: ω=arc ctg(πd_2/T) 对于圆柱形螺纹,每一点的d_2均相等, When using the imaging method to measure the parameters that characterize the accuracy of the male thread, the post of the central microscope should be tilted at an angle (hereinafter referred to as the helix angle) such that the light projected by the light source is not reflected by the helical surface of the thread Blocked. The relation between helix angle ω and thread diameter d_2 and lead T is: ω = arc ctg (πd_2 / T) For cylindrical thread, every point d_2 is equal,