Forward and reverse extrusion method of aluminum profile

The extrusion method classified according to the direction is mainly based on whether the direction in which the extrusion axis runs is opposite or the same as the direction in which the aluminum product moves. If the direction is the same, it means that it is the forward extrusion of the aluminum profile.

forward extrusion

Positive extrusion is a fairly basic method, because this extrusion method is simple to operate, relatively flexible, and has a smooth extrusion surface. It is relatively mature and widely used in the forming and processing of aluminum and aluminum alloy materials. the

The points that need to be paid attention to in positive extrusion are: the sliding between the aluminum profile blank and the extrusion cylinder will generate a large sliding friction during extrusion, and this friction is not conducive to the extrusion of aluminum products in most cases , because this will make the moving speed of the aluminum product not constant, resulting in uneven force on each part of the aluminum product, and the quality of the final extruded aluminum profile product is uneven; and under the action of friction alone, the machine consumes The energy has increased by as much as 30%-40%; due to the heat generated by the strong friction, as the relative speed between the extrusion of the aluminum product and the mold wall will increase, the wear and tear of the mold will also increase accordingly, and the life will be shortened. will decrease accordingly.

reverse extrusion

The opposite of forward extrusion is that if the movement direction of aluminum products is opposite to the direction of extrusion axis movement, it is called reverse extrusion. the

The aluminum profile reverse extrusion method is mainly used for the cold extrusion forming of various aluminum alloy die-casting; and the hot extrusion forming of aluminum alloy round pipes and profiles, among which high-strength aluminum alloys are relatively widely used. There is no need for relative sliding between the metal billet and the wall of the extrusion cylinder during reverse extrusion, and the required extrusion force and extrusion energy consumption are relatively low. Therefore, on the same level of equipment, reverse extrusion can be larger The amplitude deforms the aluminum profile, or extrudes an alloy with higher deformation resistance. With the successful development of special back-extrusion machines and the development of tooling technology, aluminum alloy back-extrusion technology will be used more and more. the

Using reverse extrusion has the following advantages:

Since there is no friction between the billet and the extrusion cylinder, the extrusion force is much lower than that of forward extrusion. During the reverse extrusion process, the extrusion force remains constant throughout the entire stroke of the extrusion rod. Difficult-to-deform materials can be extruded at lower temperatures with higher extrusion coefficients. the

The metal deformation is uniform, and the structure and mechanical properties along the length of the extruded product are basically the same. the

Compared with forward extrusion, waste materials such as overpressure are significantly reduced, and there is a higher yield; larger ingots can be used, which helps to improve equipment efficiency and continuous production. Compared with the forward extrusion method, the reverse extrusion method also has the following disadvantages:

The extrusion cylinder of the aluminum extrusion machine must be able to move. In order to ensure the production efficiency during reverse extrusion, the stroke of the extrusion cylinder should be slightly longer than the length of the extrusion cylinder. Therefore, not any extrusion machine can be suitable for reverse extrusion. The back-extrusion gap time is long, so it is difficult to control the quality of the surface of the aluminum product during the reverse extrusion, and the surface quality of the extruded aluminum is low. the

The operation of reverse extrusion technology is more complicated, and the gap time is longer than that of positive extrusion. The extrusion cycle is generally longer than that of forward extrusion. However, because the size and quality of the billet can be increased, the residual pressure loss is small, and the extrusion speed is high, the increase in auxiliary time is compensated to a certain extent, so that the reverse extrusion has higher production efficiency. the

The maximum circumscribed circle diameter of extruded aluminum is limited by the strength of the hollow extruded rod.