What are the technical requirements of cold forging?
The forming precision of cold forging technology is higher than that of warm forging and hot forging. It 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 bore, prolongs the life of the barrel, improves the shooting accuracy of the gun correspondingly, and is convenient for machining the cone barrel and reduces the quality.
Cold precision forging is a (near) net shaping process. The parts formed by this method have high strength, high precision and good surface quality. At present, the total amount of cold forgings used in an ordinary car abroad is 40~45kg, among which the total amount of toothed parts reaches more than 10kg. The weight of the cold forging gear can reach more than 1kg, and the precision of the tooth shape can reach 7 levels.
Continuous process innovation promotes the development of cold extrusion technology. Since 1980s, precision forging experts at home and abroad began to apply the shunt forging theory to cold forging of spur 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, part of the material flows to the shunt cavity or the shunt channel while filling the cavity. The application of shunt forging technology makes the machining of high precision gear with less and no cutting rapidly reach the scale of industrialization. For the extruded parts with the length-diameter ratio of 5, such as the piston pin, the cold extrusion forming can be realized by using the axial residual block widely through the axial shunt, and the punch stability is very good; For flat spur gear forming, cold extrusion can also be achieved by using radial spare block.
Block forging is a near-clean precision forgings without flying edges, which are formed in a closed die by one or two punches extruding the metal in one direction or in opposite direction. Some car precision parts such as planet and half shaft gear, star sleeve, cross bearing, etc., if the cutting method is adopted, not only the material utilization rate is very low (average less than 40%), but also the cost of time, high production cost. In foreign countries, block forging technology is used to produce these net forgings, which saves most of the cutting and greatly reduces the cost.
The forming precision of cold forging technology is higher than that of warm forging and hot forging. It 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 bore, prolongs the life of the barrel, improves the shooting accuracy of the gun correspondingly, and is convenient for machining the cone barrel and reduces the quality. The cold forging process was first proposed by Steyr Company, and later many countries in the world adopted Steyr's cold forging machine to process the barrel.
