The research on spur gear forging at home and abroad mainly focuses on the precision forging of spur gears.
The research on precision forging of spur gear abroad is earlier and the technology is more advanced. At present, Germany, Japan, the United States and other industrialized countries are in a leading position in the precision forging technology of spur gears. Many foreign experts and scholars have studied the precision forging technology of spur gears.
K Kondo studied the cold precision forging of spur gear with boss, and put forward the centripetal and centrifugal flow conditions during the cold precision forging of spur gear; The principle of floating die for precision forging spur gear is put forward. The tooth profile of the gear forged by this method is fully filled, but this die is not suitable for the case of large deformation force; At the same time, a shunting principle is proposed for cold precision forging spur gears. Shunting means that there is a phenomenon that the direction of metal flow velocity is opposite in the metal deformation zone during the forging process. The shunting principle means that the non working face of spur gears is provided with overflow ports, so that there is always material shunting during the forging process, The sudden increase of load in the last stage of block forging process is avoided.
E. Doege and r.bohnsack put forward the method of hot forging spur and helical gears with alternate closing devices. In the traditional closed die forging, more than 50% of the pressure is only used for closing the die without deformation. Their new method can avoid this situation. Cai J and dean T. A studied the forging die. They designed the punch as plane and inclined plane, and the die as fixed and floating respectively. They studied the metal flow and the required load under different schemes. The results showed that when the inclined punch and floating die were used, the metal filling was the most full and the forming load was the lowest.