Gear is the most widely used mechanical transmission parts, with a compact structure, large transmission power, high efficiency, long life, good reliability and accurate transmission ratio and other characteristics. The precision forging and pressing technology of gears has its remarkable advantages. It is getting more and more attention from researchers all over the world.
Gear precision forging technology is a gear manufacturing technology in which the gear teeth are directly formed by precision forging of the blank, and the tooth surface is not machined or can be used only with a little finishing. Compared with the traditional cutting process, gear precision forging divination has the following characteristics:
(1) improve the structure of the gear, improve its mechanical properties. Precision forging enables the fiber structure of the metal material to be uniformly and continuously distributed along the tooth shape, with fine grains and microstructure and fewer micro-defects. Therefore, the performance of precision forging gears is superior, and the bending strength, contact fatigue strength and impact resistance of the teeth are significantly higher than those of cutting gears. Generally speaking, precision forging can increase the impact strength of wheel teeth by about 15% and the bending fatigue life by about 20%.
(2) improved production efficiency and material utilization rate. Through precision forging forming, the precision of gear can reach the precision tolerance standard, without or only requires a small amount of follow-up finishing, that is, it can be heat treated or directly put into use, with high productivity and material utilization rate.
(3) precision forging gears reduce the tooth profile deformation during heat treatment, improve the wear resistance of teeth and the stability of gear meshing, and improve the service life of gears. Although gear forging has many advantages and the precision forging technology of straight bevel gear has been successfully applied in production, many difficulties have been encountered in the precision forging of spur gear because of the difficulties in filling the tooth cavity (especially in the upper and lower corners), large forming force and strict requirements on mold design and manufacturing accuracy. Over the years, researchers in various countries have made unremitting research on the precision forging technology of spur gears by using various theories, technical means and test methods.