CATIA software is used to complete the three-dimensional modeling of upper die, lower die and cold precision forging preforms with different cold precision forging quantities. In order to realize the data connection with DEFORM-3D software, the digital analog is saved into a general standard format and imported into DEFORM-3D software one by one.
For the setting of pre-processing simulation parameters:
- Because the driven spiral bevel gear material studied in this paper is 20CrMoH, but there is no such material in DEFORM-3D material database, aisi4120 with very similar material properties is selected as the workpiece material in simulation, and the workpiece is set as plastic body;
- Because this part focuses on the tooth shape optimization of the driven spiral bevel gear blank and the cold precision forging process temperature is normal temperature, the die temperature has little effect on the workpiece forming process; In order to improve the operation efficiency, the mold is simplified as a rigid body without meshing; Set the temperature of cold precision forging preform to the default 20 ℃;
- Tetrahedral element type is selected to better represent the meshing of gears with complex geometric conditions; The relative mesh generation mode is adopted, and the number of meshes is set to 200000, and the FEM + mesh mode is turned on, so as to activate automatic compensation to make up for the volume difference caused by mesh distortion in the process of gear forming;
- Considering the positioning problem of gear blank on the die bore and the geometric characteristics of gear blank in actual production, the tooth die is set as the lower die;
- Set the movement speed of the upper die to 26mm / sec;
- The workpiece is cold precision forged after surface treatment and phosphorus saponification treatment, so the workpiece and die are well lubricated, so the friction coefficient is 0.12;
- Set the thermal conductivity between workpiece and air to 5;
- Check that the minimum size of the workpiece mesh is about 0.9mm. Considering the simulation accuracy and time efficiency, the simulation step is set to one third of the minimum size of the workpiece mesh, i.e. 0.3mm.
The figure shows the cold precision forging model of spiral bevel gear blank after setting parameters.