Because of the high hardness of the surface of the gear after heat treatment, the traditional hot post-processing process is to process the hole after clamping the pitch circle of the workpiece with a hole-grinding fixture. The advantage of this processing method is The dimensional accuracy of the workpiece hole and the geometric accuracy of the hole to the gear pitch circle can be better guaranteed. Its disadvantages are low production efficiency and high processing costs. With the widespread use of CNC machine tools, coating jigs can ensure the machining accuracy of gear holes after heat treatment by using the superior performance of CNC machine tools. As long as the design of the fixture is reasonable and the selection of reasonable cutting tools and cutting parameters, the coating jig can not only guarantee the technical quality requirements of the workpiece, but also greatly improve the production efficiency. The fixture structure design for the inner hole turning processing of single gear and double gear is analyzed and discussed.

The design drawing of the single-joint structure of the painting jig is the jig structure for turning the hot back hole of the single-joint gear. It is mainly composed of round rods and connecting pins for coating jigs. The working principle is that the workpiece is positioned in the gear clamp ring through three pitch mandrels, and the coating jig restricts the 5 degrees of freedom of the workpiece; the left end of the workpiece is close to the inner surface of the gear clamp ring, limiting the axial freedom of the workpiece. So that the workpiece can be accurately positioned. Then clamp the left end surface and outer circle of the entire fixture on the three-jaw self-centering chuck of the CNC lathe (note that the direction of the three-jaw self-centering chuck is basically aligned with the three pitch rods in the gear clamp ring , Paint fixture to ensure uniform force and deformation of gear clamp ring and prolong service life). The gear clamp ring and pitch mandrel should be designed and calculated according to the parameters of the wheel.