这是一个准确度要求比较高的沉头螺钉。为力求以整个横截圆接触,减少螺纹拧紧后的弯曲,给出圆锥形支承面对螺纹中心线A的法向圆跳动。tt为保证与法兰的圆锥形沉孔接触良好,再给出素线对中心线A倾斜度,以同时限制圆锥角的角度误差和素线的直线度误差。为求以大端接触, This is a higher accuracy countersunk head screw. In order to strive to contact the entire cross-section of the circle to reduce the thread after tightening the curve, giving the cone-shaped support surface facing the centerline of the thread A normal circular beating. t tIn order to ensure good contact with the conical countersink of the flange, the inclination of the centerline A to the centerline A is also given to limit the angle error of the cone angle and the straightness error of the plain line. In order to contact with the big end,