Due to the material head, the material utilization rate is not high and the coaxiality of the product is not good. Due to the subsequent process of processing spiral bevel teeth in the driving spiral bevel gear blank, the requirements for the conical head of the gear blank are very strict, while the cross wedge rolling method has incomplete constraints on the rolled piece, the accuracy of the formed conical head is not high, and the quality of the subsequent processed teeth can not be guaranteed due to the influence of repeated rubbing. Because closed die forging can precisely forge some parts with regular geometry. Therefore, it is considered to use the advantages of cross wedge rolling process to roll the billet shaft of spiral bevel gear, and then combine the advantages of closed die forging to precision forge the billet cone head of spiral bevel gear.
The forming of driving spiral bevel gear blank by cross wedge rolling vertical forging process was studied. The shape and size of the step shaft formed in the previous cross wedge rolling process are ideal. However, due to the forming characteristics of cross wedge rolling, a pit is formed at the end of the rolled piece. Since the workpiece has no head, the pit needs to be filled in the vertical forging stage. In the vertical forging process, after many designs and experiments, the appropriate vertical forging die bore is finally determined. The pit at the end of the workpiece is filled quickly and completely in the later stage of vertical forging. At the same time, the micro bending and raised burr produced in the cross wedge rolling process have been corrected and finished in the vertical forging process. From the final formed driving spiral bevel gear blank, the shape is relatively regular and the dimensional error is relatively small. On the whole, the workpiece quality is better than that formed by cross wedge rolling process. However, due to the two processes and the slow speed of vertical forging process, the production efficiency is greatly reduced compared with cross wedge rolling process.