Extrusion Press Machine 1600 Tons (6 Inches)
Production of aluminum profiles by extrusion method:
Extrusion is generally a process in which aluminum billets, under pressure, pass through a mold with a specific shape and produce a cross-sectional area. Extrusion has different methods, the most common and simplest form is direct extrusion. The container of the device is made of several layers of steel (usually two layers) and is usually able to withstand very high radial stresses. To produce aluminum profiles, aluminum billets that have already reached the appropriate production temperature in the preheating furnace are placed inside the machine.
The trap is then placed behind the billet and the mandrel presses on the billet by means of powerful hydraulic cylinders. Due to the applied pressure, the temperature rises and semi-molten and paste-like materials pass through the mold and form the shape of the profile. The presence of frictional forces significantly increases the pressure of the press.
It has been experimentally observed that in the first phase of production, when the billet is placed behind the mold, the pressure of the machine increases rapidly to its maximum value and the production status of the profile is unstable. To correct and determine the problems of the mold, they use the protruding branch of the mold, which expresses the problems in production. The extruded profile that comes out of the mold must be pulled out manually or automatically. This greatly reduces the pressure and helps to produce the desired profile. The puller machine pulls out the profile with one hand and with equal force and places it on the rails in front of the machine. This greatly helps to twist and modify the complexity of the profile. In the second phase of billet production, it will reach a stable state and the pressure on the machine will be reduced, and the profile will be of good quality. In the third phase, the billet is gradually completed, the pressure on the device reaches its minimum.
After finishing one billet, the next billets are placed in the machine in a row. In this way, profiles of infinite length can be produced. After production, the extruded profiles can be cut to the desired dimensions with a saw. Usually in the production process, 6 to 8% of the length of the billet is the end area that is not used in the process and is called the bottom of the billet. Temperature is a very important element in the production process of extrusion profiles. As the temperature rises, the stress of the material decreases and extrusion becomes easier, but the temperature may also reach the melting point of the alloy, which causes the loss of the desired properties for the alloys used in production. Increasing the speed of the ROM increases the pressure and consequently raises its temperature.
At lower ROM speeds, the heat generated for the transfer is lower as well as the profile production speed is lower. To reduce production waste, temperature, pressure and speed must be controlled at all stages of production. The complexity of the relationships between these three variables has caused the tolerance of the stiffness of the produced profiles to be different.
Extrusion is an aluminum deformation process in which an aluminum metal block (billet) passes through a mold with a smaller cross section due to pressure. Extrusion is in fact an indirect compaction process. The forces required for this compaction are generated by the contact of the billet with the mold chamber and the mold, the amounts of which are very large. Contact of the billet with the mold and mold chamber leads to high compressive stresses which reduce the possibility of surface cracking of the billet during the process. Aluminum extrusion is the best way to break the casting structure of the aluminum billet because in this process the billet only It is affected by compressive forces. Depending on the type of alloy and the desired method, extrusion can be done hot or cold.
In hot extrusion, the billet is preheated to facilitate plastic deformation.
In direct extrusion, which is the most common method used in aluminum extrusion, the billet is placed inside the mold chamber and pushed into the mold with a smooth pressure. The direct extrusion method is used in the production of aluminum rebar, aluminum wire, aluminum pipe and hollow and hollow aluminum sections.
In direct extrusion, the metal flow is in the same direction as the smooth motion. The billet slides on the wall of the mold chamber during the process.
The presence of frictional forces significantly increases the pressure required by the ROM. Once the extrusion is complete, surface treatment is usually necessary to improve corrosion and oxidation resistance.