Precision forging method of gear

There are roughly two methods for precision forging of gears:

(1) Traditional closed die forging

Closed die forging, also known as non flash die forging. During the forging process, the gap between the upper die and the lower die remains unchanged. The blank is formed in the closed die chamber around without transverse flash. A small amount of excess material will form longitudinal burrs, which can be removed in the subsequent process. In the process of closed die forging, the upper die and the lower die are first contacted and closed to form a closed die chamber, and sufficient die closing force is applied to it, and then the blank in the die chamber is extruded from one direction or two directions with the upper punch or the lower punch or the upper and lower punches together, In special cases, it can also be extruded in multiple directions without metal outflow, so as to obtain large deformation and complex profile in one deformation and complete the plastic forming of complex parts. Closed die forging can improve the plasticity of forging materials, reduce noise, reduce vibration and improve the automation of forging machinery. At the same time, the geometry, quality and dimensional accuracy of the forgings of closed die forging are very close to the products, which is a common method of gear precision forging. However, there is a defect in this method. When the blank enters the lower die, the blank will be subjected to the upward friction exerted by the lower die, and the friction will increase with the increase of deformation. In this way, the material flow is difficult, and it is easy to stay at the upper end of the die cavity, so that the lower end is not fully filled.

(2) Floating die closed die forging

In view of the defects of traditional closed die forging, a floating die principle is proposed: the die is designed into a floating structure to make the die move downward relative to the blank, and the effective friction between the die and the blank is used to make the material flow downward, so as to fill the lower end of the die cavity.

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