The precision forging adopts the closed die forging die. During the forging process, the gap between the upper die and the lower die remains unchanged. The blank is formed in the surrounding closed die chamber without horizontal flash. A small amount of excess material will form longitudinal Flying Spur, which can be removed in the subsequent process. The advantage of closed die forging is that the geometry, dimensional accuracy and surface quality of the forging are close to the product to the greatest extent, Compared with open die forging, closed die forging can greatly improve the utilization of metal materials, which belongs to near net shape forming process.
The process of closed die forging shall meet the following conditions:
1.The blank volume shall be accurate, and the blank volume shall be slightly larger than the volume of spiral bevel gear, so as to prevent tooth defects caused by insufficient tooth profile forging in the forming process.
2.The blank shape must be reasonable and can be accurately positioned in the die bore. Through the blank design similar to the spiral bevel gear, the deformation part can be reduced as much as possible, so that the gear tooth part is the main deformation part, and the blank inner hole is designed to be slightly larger than the positioning shaft in the spiral bevel gear die, which is convenient for installation and die out.
3.The striking energy or force of the equipment can be controlled. The forging pressure required in the die forging process may vary greatly according to the uneven internal texture of the blank. Strong impact between the upper and lower dies of die forging should be avoided, otherwise the service life of the spiral bevel gear die will be greatly reduced or even damaged.
4.The equipment is equipped with ejection device. In order to ensure continuous production characteristics, the ejection device shall be designed on the die forging die in actual production to facilitate the ejection of forgings and ensure the efficiency of forging.
Due to the need to meet a variety of conditions, the actual production and processing of spiral bevel gear mold has a very complex structure, some positioning parts and cooling or heating and other functional modules have similarities, and occupy a large mold specific space. Therefore, the established spiral bevel gear mold model omits the above parts and is a simplified model, Only the die cavity of spiral bevel gear and its support are retained.