Prospect of compound forming technology of continuous cold extrusion and cold shaping of spur cylindrical gears for trucks

The compound forming process of continuous “cold extrusion + cold shaping” of spur gear is studied, mainly for the purpose of improving the forming quality and accuracy of spur gear. In future research, further research and exploration can be made from the following points:

① The cold extrusion forming process of large module spur gear is complex, with large deformation degree and violent metal flow. The phosphorus saponification layer is easy to become thinner or even damaged in the forming process, resulting in die sticking and strain defects. How to avoid the rupture of lubrication layer and improve the lubricity is one of the difficult problems in the cold extrusion of large modulus spur gears.

② Although the microstructure after composite forming is observed in this paper, the microstructure evolution is not studied. Therefore, in the future research, the microstructure evolution of materials in hot forging gear blank, spheroidizing annealing and spur gear composite forming is simulated and predicted by establishing the constitutive relationship and microstructure evolution model of materials and numerical simulation analysis.

③ After compound forming, the spur gear needs to turn two end faces and turn the outer circle in the subsequent machining. If the positioning datum is not found out in the subsequent turning of end faces, it will affect the accuracy of spur gear. Therefore, how to machine the spur gear after compound forming stably and efficiently is the key to ensure the product quality. The selection of machining benchmark after compound forming should be considered in the subsequent research.

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