According to the load stroke curve of the spur bevel gear in the figure, the load change can be basically divided into three stages:
In the first stage, the metal flow law is similar to upsetting, and the load rises slowly;
In the second stage, the metal begins to fill the tooth cavity under the resistance of the tooth die at the small end of the spur bevel gear. With the continuous filling of the tooth cavity, the metal flow surface decreases rapidly, and the load begins to accelerate;
In the third stage, the tooth cavity of the spur bevel gear is basically full, the metal mainly flows laterally to the top of the big end tooth, and the load rises sharply.