Spur Gear Precise Plastic Forming Processes Research

Gear is very important driving parts which is used widely, and its manufacturing batch is very large. Gear can be manufactured in two ways, one is machining processing, the other is plastic forming. To the traditional mechanical processing, there is a lot of disadvantages to it. It can not satisfied the requirement of industry because of the low utilization rate of material, the low productivity and the high output cost. What's more important is that metal flow line of the billet would be cut off, and the mechanical property of the product would reduce. The Precision Forming is an advanced technology. It may not only lift material utilization from 40% to 70%, but also lift the gear strength over 20% and production efficiency over 40%.This paper deals with precision forging of spur gears. In China, Gear precision forming technology is mainly researched in lab now. The largest problem is the punch force increasing sharply at last and metal can not fill up the die entirely. Cone, as constrained divided flow device, is used to fill up the spur gear. The gears can be formed in one step process operation.By the adoption of active die-Cone constrained divided flow method, in this paper, the die is specially designed and manufactured for precision cold forging of spur gears. The technological experiment on the precision forging of spur gears has been done. And the material of the billet is Al. Then with the well developed numerical simulation software-Deform, the author simulate some forming processes, which include upset-extrusion pre-forging, relief hole, restrained hole divided flow. Then, author analysis some stress and strain charts, force-stroke relationship charts, some velocity cloud charts. The result of the numerical simulation and the experiments showed that the divided flow, especially the active die-Cone constrained divided flow applied in the final forging stage, was very effective on improving the gears teeth filling and decreasing the forging load.The result that author made from this analyses can used in the real production. On the base of the pattern that author made, designers can carry on the deeper analysis. They can optimize to the main design parameter try means of the imitation in the actual manufacture.