The gear blank used for forging is aisi4120 steel, and its material composition and mass fraction are shown in the table.
| C | Mn | P | S | Si | Cr | Mo |
| 18~23 | 90~20 | ≤0. 035 | ≤0. 040 | 15~35 | 40~60 | 13~20 |
The original gear blank size is Φ 60 mm × A 30 mm cylinder with a rectangular longitudinal section. The shape of gear preform is extracted by electric field method. In order to obtain the appropriate equipotential line, the gear blank section needs to be enlarged so that the final forging can be placed in the gear blank section. After many attempts, the gear blank is enlarged by 2 After 6 times, the section of the final forging is placed in it to obtain the geometric model of electric field analysis, as shown in Figure 1a. The geometric model shown in Fig. 1a is meshed by finite element method. The four node quadrilateral element is selected for the mesh. 1 V voltage is applied to the gear blank contour and 0 V voltage is applied to the final forging contour. The electrostatic field analysis method is used to simulate based on ANSYS software, and the equipotential distribution of the electric field is obtained, as shown in Fig. 1b. Because the forging is axisymmetric, only 1 / 2 of it is simulated.
It can be seen from Fig. 1b that when the potential is too small, the shape of equipotential line is very similar to that of final forging; When the electric potential is too large, the shape of equipotential line is very similar to the contour of gear blank. Therefore, when the potential is too large or too small, the shape of equipotential line can not achieve the purpose of preform design. After analysis, the selected potential is 0.5% 05~0. The equipotential line shape between 45 V is used as the optimization and selection object.
The interactive medical image control system (Mimics software) is used to extract the equipotential line from the simulation results of ANSYS software, and then it is scaled in equal proportion according to the principle of equal space volume of forgings to obtain the preformed shape. With 0 Taking 4 V equipotential line as an example, the equipotential line before and after scaling is shown in Figure 2.