The new process flow of precision forging of spiral bevel gear is as follows: blanking → less and no oxidation heating → blank making → precision die forging → fine pressing → surface cleaning → boring and turning the part outside the tooth surface → heat treatment → fine grinding the inner hole. Compared with the open die forging process, the new process greatly simplifies the forming process, significantly improves the production efficiency and reduces the production cost. Figure 1 shows the deformation steps of the new forming process of spiral bevel gear, including blanking, upsetting, punching, reaming, precision die forging and precision pressing.
The forging drawing of spiral bevel gear is formulated according to the requirements of its part drawing. The formulation of forging drawing mainly includes selecting the position of parting surface, determining the tolerance and allowance of forging machining, setting die forging slope and fillet radius, etc
1) Based on the geometry of spiral bevel gear and considering that the blank metal has the best filling conditions and the forging has the best fiber streamline distribution, the parting surface of the forging is set at its maximum outer profile.
2) It can be seen from the part drawing of spiral bevel gear that the tooth shape of spiral bevel gear itself is inclined, and this slope can be used as the die forging slope to obtain a good demoulding effect.
3) The determination of machining allowance and dimensional tolerance of forgings mainly considers the weight, shape complexity coefficient, material coefficient, parting line shape, machining accuracy of parts, etc. since the dimensional accuracy and surface roughness of tooth profile of spiral bevel gear have met the requirements of parts after being formed by new precision forging process, machining allowance is not required, Only 1mm machining allowance is reserved for the upper and lower end faces of the spiral bevel gear.
4) The addition of external fillets is mainly to eliminate the sharp corners of the die to prevent the damage of the die due to stress concentration, while the addition of internal fillets is to make the metal easy to flow and form in the forming process.
Through the above analysis and parameter determination, the forging drawing and three-dimensional modeling drawing of the driven spiral bevel gear are obtained, as shown in figures 2 and 3.
