The 18CrNiMo7-6 spur gear provided by Zhengzhou Machinery Research Institute is taken as the research object, and the product part drawing is shown in the figure.
From the above, it can be seen that the spur gear is a small and medium-sized gear with large modulus (M = 5), large number of teeth and large diameter. There are central holes, and the end faces at both ends are chamfered and small bosses. The accuracy grade of the spur gear is required to be high. The inner hole and end face are the positioning datum. The accuracy of the end face and hole of the part is required to be grade 7, and the surface roughness Ra is 0.8 respectively μ M and 1.6 μ m。 The surface roughness of tooth top and tooth surface of spur gear is RA3 two μ M and Ra0 eight μ m. The surface quality of tooth surface is required to be high.