After the calculation of pre punching process is completed, enter the forming module of software pre-processing, add punching steps and complete the parameter input of punching steps. The geometric shapes of the upper and lower dies for the blank punching of spiral bevel gear are shown in Fig. 1 (a) and 1 (b) respectively. For the upper punching die of spiral bevel gear blank, enter its bottom radius and height in define primitive geometry, and the geometric input data of the lower punching die edit geometry table is shown in the table below. The punching size of spiral bevel gear blank is φ 100mm, the thickness of skin is 5mm, and the blanking volume is 39270mm ³。 The volume of driven spiral bevel gear blank after punching is 6876318-39270 = 6837048mm ³。
| X | Y | R |
| 50 | 0 | 0 |
| 88 | -38 | 0 |
| 150 | -38 | 0 |
| 210 | -25.25 | 0 |
| 210 | -80 | 0 |
| 50 | -80 | 0 |
| 50 | 0 | 0 |
This numerical relationship involves the state of stress and strain, which affects the subsequent deformation. From the previous formula, we can judge whether the fracture begins to form. This is the discriminant formula of “fracture”. Whether fracture occurs at each point in the deformation area can be judged by the integral in the formula. These integrals can be easily realized by transformation, integration and summation in finite element program. When the calculated value reaches its critical ductile fracture value, the fracture begins to occur. According to the maximum value of damage of upsetting and pre punching blank, set the critical threshold of fracture to 0.5 and the fracture elements of blank to 4. The blanking clearance has a great impact on the quality of the section. In order to obtain a smooth blanking section, a sufficiently small blanking clearance should be adopted. After the punching of spiral bevel gear blank is completed, the blanking metal will disappear automatically. The initial diagram and completion diagram of spiral bevel gear blank punching process are shown in Fig. 2 (a) and Fig. 2 (b) respectively.
