If the normal section in the center of the tooth line is taken as a tooth measuring and design section, when spline hob is designed in a plane meshing, the tooth profile error is minimum.
如果以齿纹中点法剖面作为齿形检测和设计剖面，用平面啮合法设计花键滚刀时，则齿形误差最小。
2
The new tooth surface can be prolonged by the normalprofile of the internal toroidal surface, or replaced by an equal pitch helical surface.
其二为一种修整的线接触，展成的等螺距齿面与理论轨迹曲面沿某一空间曲线近似相切。
3
Meanwhile obtained the toothprofile equation of pin-track by the toothprofilenormal law which matched the inviolate-cycloid compound gear.