As shown in the figure, the flow direction diagram of metal materials in different stages of bevel gear tooth profile finishing process can also be divided into three stages by observing the flow direction of materials:
In the initial stage, that is, the bevel gear tooth shape part gradually contacts with the concave die tooth shape cavity, and the metal flow direction in the initial stage is consistent with the tangent direction of each point on the concave die tooth surface;
In the middle stage, i.e. the cold finishing stage of bevel gear tooth profile, some metal materials move axially to fill the bevel gear tooth cavity of the die, and the other part of metal materials move tangentially along the tooth surface of the die due to the obstruction of the tooth cavity surface of the die;
In the later stage, that is, the end stage of cold finishing, after the tooth surface of the bevel gear tooth blank is finished, the tooth top of the bevel gear tooth blank contacts with the tooth root of the concave die tooth cavity. At this time, the metal material has filled the concave die tooth cavity, and the excess metal flows to the large and small ends of the bevel gear, alleviating the increase of forming force.