Die forging processes can be classified according to the following principles: According to the flow conditions of metal deformation, it can be divided into open die forging and closed die forging; According to the temperature of the blank during die forging, it can be divided into hot forging, warm forging and cold forging. According to the combination form of die forging process, it can be divided into single groove die forging and multi-groove die forging, continuous die forging and combined die forging. Common joint die forging are: free forging hammer billet - a die forging hammer pre-forging and final forging; Roll forging machine billet - crank press pre-forging and final forging; Pre-forging and final forging with hammer or press; Electrically sensitive roughing-one press final forging; Hammer sensitive coarse and punching - ring rolling machine reaming, etc. In addition, according to the forging equipment, it can be divided into hammer die forging, flat forging machine die forging, crank press die forging, screw press and hydraulic press die forging, etc.