Cold precision forging is a (near) net forming process. The parts formed by this method have high strength and precision and good surface quality. At present, the total amount of cold forgings used in an ordinary car abroad is 40~45kg, of which the total amount of tooth-shaped parts is more than 10kg. The weight of a cold-forged gear can reach more than 1kg, and the tooth profile accuracy can reach level 7.

Continuous process innovation has promoted the development of cold extrusion technology. Since the 1980s, domestic and foreign precision forging experts have begun to apply split forging theory to cold forging forming of spur gears and helical gears. The main principle of shunt forging is to establish a material shunt cavity or shunt channel in the forming part of the blank or die. During the forging process, while the material fills the cavity, part of the material flows to the shunt cavity or shunt channel. The application of shunt forging technology enables the small and no-cutting processing of high-precision gears to quickly reach industrial scale. For extruded parts with a length-to-diameter ratio of 5, such as piston pins, a cold extrusion can be achieved by adopting a wide range of axial residual material through axial splitting, and the stability of the punch is very good; for flat spur gears Forming, the use of radial residual material block can also realize the cold extrusion of the product.

Blocked forging is to form one or two punches one-way or oppositely extruding metal in a closed die to obtain a near-net-shape precision forging without flash. Some car precision parts such as planetary and semi-axle gears, star sleeves, cross bearings, etc., if cutting processing methods are used, not only the material utilization rate is very low (less than 40% on average), but it also consumes a lot of man-hours and extremely high production costs. Foreign countries adopt occluded forging technology to produce these net-shape forgings, which saves most of the cutting processing and greatly reduces the cost. [1] 

skills requirement

Cold forging technology has higher forming accuracy than warm forging and hot forging, and has its unique advantages in the field of precision forming. The application of cold forging technology improves the smoothness, dimensional accuracy and surface strength of the inner chamber, prolongs the life of the barrel, improves the shooting accuracy of the gun correspondingly, and facilitates the processing of the tapered barrel, which can reduce the quality. The cold forging process was first proposed by Steyr. Later, many countries in the world used Steyr's cold forging machine tools to process barrels.