There are two main machining methods of spiral bevel gears, forming method and generating method.
The profile of theprocessed by the forming method is the same as that of the cutting edge. For the spiral pair whose transmission ratio is more than 2.5, the profile shape of the spiral bevel gear big wheel can be approximately replaced by the profile of the linear shape, so that the forming method can be used for processing. However, due to the errors in the profile of the spiral bevel gears processed by the forming method, the corresponding profile modification of the matched pinion needs to be carried out by the generating method, which is called the half hobbing method or the forming method. This kind of bevel gear cutting method has high production efficiency and is suitable for mass production.
The generating method is that the high-speed rotating milling cutter head and the bevel gear to be machined move in a certain proportion, and the high-speed rotating cutter tooth envelope layer by layer along the tooth top to the tooth root direction to cut the spiral bevel gear tooth surface, as shown in the figure. When using this method to cut teeth, because the width of the top of the cutting edge is limited by the width of the tooth root groove of the small end of the spiral bevel gear to be machined, the cutting process is generally divided into three steps: rough cutting the tooth groove → fine cutting (hobbing) one of the bevel gear tooth surfaces → fine cutting (hobbing) the other tooth surface.
There are many ways to use the combination of the above two methods to cut the spiral bevel gear. Among them, the rough machining mainly uses the double-sided edge milling cutter head to mill the convex and concave tooth surfaces of the spiral bevel gear at the same time. The main finishing methods are single-sided cutting, double-sided cutting and double-sided machining. The double-sided cutting method includes: double-sided cutting, fixed installation, half hobbing and spiral forming.