Views:3 Author:Jia Hua Aluminium Co., Ltd Publish Time: 2019-09-23 Origin:Site
Aluminum extrusion molding definition
Aluminum extrusion molding exerts a strong pressure on the metal blank placed in the mold cavity (or extrusion barrel), forcing the metal blank to undergo directional plastic deformation, and extruding from the die hole of the extrusion die to obtain the desired section. Plastic working method for parts or semi-finished products of shape, size and certain mechanical properties.
Classification of aluminum extrusion
According to the metal plastic flow direction, extrusion can be divided into the following categories:
Positive extrusion: in production, the direction of metal flow is the same as the direction of motion of the punch
Back-extrusion: the direction of metal flow is opposite to the direction of motion of the punch during production
Composite extrusion: During production, part of the metal flows in the same direction as the punch, and the other part flows in the opposite direction to the punch.
Radial extrusion: at the time of production, the metal flow direction is 90 degrees from the direction of the punch movement
Process characteristics of aluminum extrusion
As shown in Fig. 1, in the extrusion process, the extruded metal can obtain a more intense and uniform three-direction compressive stress state in the deformation zone than the rolling forging, which can fully exert the plasticity of the metal to be processed;
2, extrusion molding can not only produce rods, tubes, shapes, wire products with simple cross-section shapes, but also can produce profiles and pipes with complex cross-section shapes;
3, extrusion molding flexibility, only need to replace the extrusion tools such as mold, you can produce a variety of shapes and varieties of products on a single device, the replacement of the extrusion mold operation is simple, fast, time-saving, efficient;
As shown in Fig. 4, the precision of the extruded product is high, the surface quality of the product is good, and the utilization rate and yield of the metal material are also improved;
5, the extrusion process has a good influence on the mechanical properties of the metal;
6, the process is short, the production is convenient, one-step extrusion can be more than the hot die forging or forming rolling and other methods of larger overall structural parts, less equipment investment, low mold costs, high economic efficiency;
7, aluminum alloy has good extrusion characteristics, especially suitable for extrusion processing, can be processed through a variety of extrusion processes and a variety of mold structures.
Advantages of aluminum extrusion
1, improve the deformation ability of aluminum. Aluminum is in a strong three-direction compressive stress state in the extrusion deformation zone, and its plasticity can be fully exerted to obtain a large deformation amount.
2, the comprehensive quality of products is high. Extrusion can improve the microstructure of aluminum and improve its mechanical properties. After quenching and aging, the mechanical properties of the extruded product in the longitudinal direction (extrusion direction) are much higher than those produced by other processing methods. Compared with the processing methods such as rolling and forging, the extruded product has high dimensional accuracy and good surface quality.
3, a wide range of products. Extrusion not only can produce tubes, rods and wires with simple cross-section shapes, but also can produce solid and hollow profiles with very complicated cross-section shapes. The sections of the products vary in length and gradually change in variable length profiles, many of which are Shaped articles cannot be formed by other plastic processing methods. Extruded products are also available in a wide range of sizes, from super-large tubes and profiles with a diameter of 500-1000 mm to ultra-small precision profiles with a cross-section size.
4, production flexibility. Extrusion has great flexibility. It can be used to produce shapes, sizes and varieties of products on the same equipment by changing the mold. The replacement of the mold is simple and convenient, time-consuming and efficient.
5, the process is simple, equipment investment is small. Compared with perforation rolling, hole rolling and other pipe and profile production processes, extrusion molding has the advantages of short process flow, low equipment quantity and low investment.
Disadvantages of aluminum extrusion
As shown in Figure 1, the tissue properties of the article are not uniform. Due to the uneven flow of the metal during extrusion (especially in the case of non-lubricated forward extrusion), the extruded article has a surface layer and a center, and the head and tail have poor tissue properties.
2, the working conditions of the extrusion die are bad, and the tooling wears a large amount. When the extrusion is in a nearly closed state, the three-way pressure is high, so the mold needs to withstand a high pressure. At the same time, the mold is usually subjected to high temperature and high friction during hot extrusion, which greatly affects the strength and service life of the mold.
3, production efficiency is low. Except for the continuous extrusion method developed in recent years, conventional extrusion methods cannot achieve continuous production. In general, the extrusion speed is much lower than the rolling speed, and the geometric waste of extrusion production is large and the yield is low.
In recent years, aluminum and aluminum alloy profiles have been widely used in construction, transportation, electronics, aerospace and other industries due to the pursuit of miniaturization and light weight in various industries. Therefore, the proportion of aluminum extruded products has also increased rapidly. According to the data, aluminum and aluminum alloy products in extruded products account for more than 70%.
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