Analysis of process characteristics and advantages and disadvantages of aluminum extrusion
Definition of aluminum extrusion
Aluminum extrusion molding is to apply strong pressure to the metal blank placed in the mold cavity (or extrusion barrel) to force the metal blank to undergo directional plastic deformation and extrude from the die hole of the extrusion die to obtain the required section Plastic processing method of part or semi-finished product with shape, size and certain mechanical properties.
Classification of aluminum extrusion
According to the direction of metal plastic flow, extrusion can be divided into the following categories: Positive extrusion: During production, the direction of metal flow is the same as that of the punch.
Back extrusion: During production, the direction of metal flow is opposite to that of the punch
Compound extrusion: During production, part of the metal flow direction of the billet is the same as the direction of the punch movement, and the other part of the metal flow direction is opposite to the direction of the punch movement.
Radial extrusion: During production, the direction of metal flow is 90 degrees with the direction of the punch movement
Process characteristics of aluminum extrusion
1. During the extrusion process, the extruded metal can obtain a more intense and uniform three-way compressive stress state in the deformation zone than rolling and forging, which can give full play to the plasticity of the metal being processed;
2. Extrusion molding can not only produce rods, tubes, shapes, and wire products with simple cross-sectional shapes, but also can produce profiles and pipes with complex cross-sectional shapes;
3. Extrusion molding has great flexibility. You only need to replace extrusion tools such as molds to produce products with different shapes and specifications on a single device. The operation of replacing extrusion molds is simple, fast, time-saving and efficient.
4. The precision of extruded products is high, the surface quality of the products is good, and the utilization rate and yield of metal materials are also improved;
5. The extrusion process has a good impact on the mechanical properties of the metal;
6, short process flow, convenient production, a single extrusion can be a larger area than hot die forging or forming and rolling methods, less equipment investment, low mold costs, high economic benefits;
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 deformability of aluminum. Aluminum is in a strong three-dimensional compressive stress state in the extrusion deformation zone, which can fully exert its plasticity and obtain a large amount of deformation.
2. High comprehensive product quality. Extrusion can improve the structure and mechanical properties of aluminum. After quenching and aging, the mechanical properties of the extruded product in the longitudinal direction (extrusion direction) are much higher than similar products produced by other processing methods. Compared with rolling, forging and other processing methods, extruded products have high dimensional accuracy and good surface quality.
3. Wide product range. Extrusion molding can not only produce tubes, rods and wires with simple cross-section shapes, but also can produce solid and hollow profiles with very complex cross-section shapes. The cross-sections of the products change gradually and gradually along the length. Shaped products cannot be formed by other plastic working methods. The size range of extruded products is also very wide, from ultra-large pipes and profiles with a circle outside diameter of 500-1000mm, to ultra-small precision profiles with the size of a match stick.
4. Large production flexibility. Extrusion molding has great flexibility. It can produce products with different shapes, sizes, and varieties on the same device just by changing the mold. The operation of replacing the mold is simple, convenient, time-consuming, and efficient.
5. The process is simple and the equipment investment is small. Compared with perforated rolling, hole rolling and other pipe and profile production processes, extrusion molding has the advantages of short process flow, less equipment and less investment.
Disadvantages of aluminum extrusion
1. The texture of the product is not uniform. Due to the uneven flow of the metal during extrusion (especially during non-lubricated forward extrusion), the extruded products have uneven surface and center tissue properties.
2. The working conditions of extrusion tools and molds are harsh, and the wear and tear of the tools and molds is large. The blank is in an approximately closed state during extrusion, and the three-way pressure is high, so the mold needs to withstand a high pressure. At the same time, the hot extrusion die is usually subject to high temperature and high friction, which greatly affects the strength and service life of the die. 3. Low production efficiency. Except for continuous extrusion methods 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.
to sum up
In recent years, due to the pursuit of miniaturization and lightweight in various industries, aluminum and aluminum alloy profiles have been widely used in construction, transportation, electronics, aerospace and other industries. Therefore, the proportion of aluminum extruded products has also increased rapidly. According to data, aluminum and aluminum alloy products account for more than 70% of extruded products.