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Cold extrusion forming technology
Cold extrusion is an important part of precision plastic volume forming technology. Cold extrusion refers to the cold metal blank into the mold cavity, under strong pressure and velocity, forcing the metal extrusion from the cavity, so as to obtain the required shape and size of the extrusion and has certain mechanical properties. It is clear that the cold extrusion process is to rely on the mold to control the metal flow, by a large number of metal volume transfer to the forming part of the.Get more news about Precision Cold Extrusion,you can vist our website!
Cold extrusion technology is a kind of high precision, high efficiency, high quality and low cost advanced production technology, widely used in small and medium scale production of forgings. Compared with hot forging, warm forging process, the material can be 50% ~ 30%, energy saving 40% ~ 80% and can improve the quality of forgings, improve the working environment.
At present, the cold extrusion technology has been widely used in fasteners, machinery, instruments, electrical appliances, light industry, aerospace, marine, military and other industries, has become one of the important means of processing technology indispensable metal plastic bulk forming. After World War II, the cold extrusion technology has been widely used in the development of foreign automobile, motorcycle, household appliances and other industries in developed countries, and the emergence of new extrusion materials, mold steel and large tonnage presses will expand its development space. Japan in 80s claimed that its car production in the forging process of the production of parts, there are 30% ~ 40% is the production of cold extrusion process. With the continuous improvement of the technical requirements of the product of the progress of science and technology and automobile, motorcycle, household appliances and other industries, the production of cold extrusion technology has gradually become the development direction of small and medium-sized forging production. Compared with other processing technology, cold extrusion has the following advantages:
1) saving raw materials. Cold extrusion is the use of plastic deformation of metal to make the desired shape of the parts, which can greatly reduce the cutting process, improve the utilization of materials. The material utilization ratio of cold extrusion can reach more than 80%.
2) improve labor productivity. Cold extrusion process instead of machining parts, the productivity can be increased several times, several times, and even hundreds of times.
3) the ideal surface roughness and dimensional accuracy can be obtained. The precision of parts can reach IT7 ~ IT8, the surface roughness can reach R0.2 ~ R0.6. Therefore, the parts used in cold extrusion processing is generally very little machining, only in the requirements of special high precision grinding.
4) improve the mechanical properties of parts. After cold extrusion, the metal cold work hardening, as well as the formation of a reasonable distribution of fiber lines within the parts, so that the strength of parts is much higher than the strength of raw materials. In addition, the reasonable cold extrusion technology can make the surface of the parts to form compressive stress and improve fatigue strength. Therefore, some of the original parts heat treatment can save heat treatment process for cold extrusion process, some parts of the original need made of high strength steel, cold extrusion process after available low strength steel for use.
5) can be processed in the shape of complex, difficult to machining parts. Such as profiled, complex inner, and the surface of the invisible tank etc..
6) reduce the cost of parts. The cold extrusion technology has the advantages of saving raw materials, improving the productivity, reducing the amount of machining of parts, and the poor quality materials, which can be used to reduce the cost of parts.
Cold extrusion is to place the metal blank in the cold extrusion die cavity, at room temperature, through the punch fixed on the press to exert pressure on the blank, making the metal blank produce plastic deformation and the processing method of parts. Obviously, the cold extrusion process depends on the mold to control the metal flow, and relies on a large number of metal volume transfer to form parts. In terms of extrusion equipment, China has the ability to design and manufacture various tonnage extrusion presses. In addition to the general mechanical press, hydraulic press and cold extrusion press, the friction press and high-speed and high-energy equipment are successfully used for cold extrusion production.
If the blank is extruded without heating, it is called cold extrusion. Cold extrusion is one of the processing technologies of no chip and less chip parts, so it is an advanced technology in the plastic processing of metal chips. If the blank is heated to the temperature below the recrystallization temperature for extrusion, it is called warm extrusion. Warm extrusion still has the advantage of less chips.
Cold extrusion technology is an advanced production technology with high precision, high efficiency, high quality and low consumption, which is widely used in large-scale production of medium and small forgings. Compared with hot forging and warm forging, it can save 30% ～ 50% of material and 40% ～ 80% of energy. Moreover, it can improve the quality of forgings and improve the working environment.
At present, cold extrusion technology has been widely used in fastener, machinery, instrumentation, electrical appliances, light industry, aerospace, shipbuilding, military industry and other industrial sectors, and has become one of the indispensable important processing methods in metal plastic bulk forming technology. With the progress of science and technology and the continuous improvement of product technical requirements in automobile, motorcycle, household appliances and other industries, cold extrusion production technology has gradually become the development direction of refined production of small and medium-sized forgings.
What is cold heading？
Cold heading process is one of the new technologies of less cutting metal pressure machining. It is a kind of processing method that uses the plastic deformation of metal under the action of external force and makes the metal volume redistributed and transferred with the help of mould, so as to form the required parts or blank. The cold heading process is most suitable for the production of bolts, screws, nuts, rivets, pins and other standard fasteners. The equipment commonly used in cold heading process is a special cold heading machine. If the production is not too large, it can also be replaced by crank press or friction press.
Because of its high productivity, good product quality, greatly reducing material consumption, reducing production cost and improving working conditions, cold heading technology is more and more widely used in mechanical manufacturing, especially in the production of standard fasteners. The most representative products produced by multi station cold heading machine are bolts, screws and nuts.
Cold block and cold extrusion are basically the same deformation processing conditions, but the operation mode is different. Cold pier is a kind of forging deformation of small workpiece, which is often used in fastener industry. Cold extrusion belongs to the extrusion deformation of larger workpieces and is widely used; cold upsetting is equivalent to a branch of cold extrusion. Simply speaking, in the process of bolt making, hexagon head forming belongs to cold upsetting, and rod diameter reduction belongs to cold extrusion (forward extrusion). There are both cold upsetting and cold extrusion for non chamfered hexagon flange bolts (multi position forming). The front side shaping of hexagon nut is only cold upsetting, while the hole extruding in the later process belongs to cold extrusion (forward and backward extrusion).