Introduction to cold extrusion technology

Cold extrusion refers to putting the metal blank into the die cavity in the cold state, forcing the metal to extrude from the die cavity under the action of strong pressure and certain speed, so as to obtain the extrusion parts with required shape, size and certain mechanical properties. Obviously, the cold extrusion process depends on the die to control the metal flow and the large transfer of metal volume to form parts. It is an important part of precision plastic volume forming technology.

Application field of cold extrusion technology

Cold extrusion technology has been widely used in fasteners, machinery, instruments, electrical appliances, light industry, aerospace, shipbuilding, military and other industrial departments, and has become one of the indispensable and important processing means in metal plastic volume forming technology. Moreover, the emergence of new extrusion materials, new die steel and large tonnage press has expanded its development space.

Case 1: cold extrusion is applied to precision gear forming

When the outer diameter of cylindrical gear is relatively large compared with the tooth width, the precision forming of this kind of cylindrical gear is difficult to be formed by the traditional cold extrusion method. Using closed forming, defects will also be caused at the end of the tooth due to the influence of high flow resistance. Therefore, in order to obtain high-precision and high-quality tooth profile, multi process method must be adopted, that is, the gear part must be formed several times to meet the quality requirements. The compound action closed forming method with mandrel exchange is an effective method for cylindrical gear forming. The so-called compound action forming refers to the extrusion forming process composed of two or more die actions or movements at the same station. Because it is completed in the same station, the work efficiency is high and the forming quality is guaranteed.

Cold extrusion forming steps

a. When working in the blank die, first put a gear blank in the cavity

b. The die is closed in one stroke of the slider, and the die passes through the upper and lower die closure

c. Preliminary forming gear pre forming

d. After the mandrel exchange preform is completed, the slider stops moving, and the lower mandrel pushes the upper mandrel out of the die cavity under the action of hydraulic pressure to complete the mandrel exchange

e. At this time, the slider of the press moves down for the second time to complete the final forming

f. The ejection of the workpiece is realized by pushing the ejector rod by the pressure hydraulic cylinder.

Effect of cold extrusion technology on enterprise development

Cold extrusion technology is an advanced production technology with high precision, high efficiency, high quality and low consumption. It is mostly used in the large-scale production of small and medium-sized forgings. Compared with hot forging and warm forging process, it can save 30% ~ 50% of materials and 40% ~ 80% of energy, improve the quality of forgings and improve the working environment.