Precision forging technology of spur bevel gear. Among them, the closed precision forging is selected as the forming process. Taking an automobile differential gear as the research object, the part drawing, forging drawing and forming die of spur bevel gear are designed by software. After that, the forming process is numerically simulated by software, and the simulation data are analyzed to determine the optimal process parameter combination. Under the optimized process conditions, the elastic deformation of the die and the elastic recovery of the forging after the die is out are analyzed. The initial design of the die cavity is revised by the reverse compensation method to realize the accurate design of the die cavity of the precision forging of spur bevel gear.
In the precision forging process of spur bevel gear, the basic process parameters to be set include: the size of the research object, the basic parameters of forging design, the blank size, the basic parameters of numerical simulation of forming process, etc.
The research object is an automobile differential spur bevel gear, and its dimensional parameters are shown in Table 1.
| Number of teeth | Modulus | Pressure angle° | Sub cone angle° | Tooth width° | Top cone angle° | Root cone angle° |
| 11 | 6.5 | 22.5 | 31.43 | 20 | 36.1 | 26.18 |
The basic parameters of forging preliminary design based on bevel gear parts are shown in Table 2.
| Number | h1 | h2 | s | d1 | d2 |
| 1 | 6.00 | 8.70 | 3.56 | 27.79 | 27.70 |
| 2 | 8.00 | 6.50 | 3.76 | 27.72 | 27.77 |
| 3 | 7.30 | 7.26 | 3.70 | 27.75 | 27.75 |
The ideal return volume is equal to the forging volume, and many groups of blank diameter and height combinations can be obtained. To select a workpiece with reasonable size, it should be easy to place and position in the die. Due to the characteristics of the cavity of the spur bevel gear die, the diameter of the selected workpiece is required to be smaller than the minimum tooth root circle size of the lower concave die. Secondly, the blank size should meet a certain height diameter ratio. If the height diameter ratio is too large, the forming load will increase and it is easy to fold; The height diameter ratio is too small, which is not conducive to blanking and filling.
As closed precision die forging is a forming process of cold precision forging, the forging temperature is room temperature. According to the forging process analysis, the blank material is steel. The value of each step reduction is equal to the side length of the smaller element in the model. The basic parameters of numerical simulation also include punch velocity, friction coefficient and other factors that affect the forming quality of spur bevel gears.