In the paper, the cartesian coordinates tooth profile equations of external and internal spur gear generated with pinion cutter was derived with the profile normal method, and the calculating method of starting and final point of each curve was given.

• 应用齿廓法线法,推导出插齿加工的直齿内、外齿轮的直角坐标齿廓方程,给出了齿廓各段曲线起点与终点的确定方法。