As shown in the figure, spiral bevel gear milling machines mostly use disk milling cutters, and multiple groups of blades are evenly distributed on the cutter head. When calculating the theoretical tooth surface, the cutter head is simplified into a conical surface, and each bus of the conical surface participates in the cutting of spiral bevel gear. Therefore, when calculating the theoretical tooth surface of spiral bevel gear, it is always assumed that the cutting is continuous, and the tooth surfaces of the shaping wheel and the small wheel meet the meshing conditions at any time.
In the actual machining process, the cutting edge of the cutter head is discrete without considering the tool installation error, tool wear, machine tool motion error and so on. At the same time, the linkage of X, Y axis and workpiece axis leads to the existence of residual height in the direction of tooth height. The cutting edge of the cutter head and the tooth surface of the spiral bevel gear only meet the meshing equation at the contact point.