Alloy Extrusion Forming Principle
Alloy Extrusion Forming principle
Metal extrusion processing is the use of metal plastic forming principle of an important method of pressure processing, by pressing the metal ingot once processed into tube, rod, T-type, L-type profiles. Metal Extruder is the most important equipment to achieve metal extrusion.
Extrusion is one of the main methods of non-ferrous metal, steel material production and parts forming and processing. It is also an important method for the preparation and processing of advanced materials such as composite materials and powder materials. From the large-size metal ingot hot extrusion billet, large tube rods of the hot extrusion processing to small precision parts of the cold extrusion molding, from the powder, the pellets as raw materials of the composite material directly into the intermetallic compound, Superconducting materials and other difficult to process materials, modern extrusion technology can be widely used.
Extrusion processing methods are mainly extrusion, anti-extrusion, lateral extrusion, glass lubrication extrusion, hydrostatic extrusion, continuous extrusion. Extrusion processing is characterized by a strong three-way compressive stress state, which is conducive to improving the plastic deformation of the metal, improve product quality, improve the microstructure and performance of the product. In addition, extrusion processing also has a wide range of applications, production flexibility, simple process and equipment investment characteristics. The most widely used materials for extrusion processing are low melting point colored alloys such as aluminum and aluminum alloys.
The preformed blank is placed in a cylinder (or die) and pressure is applied to extrude the material from the opening of the container. When the material is pressed in three different compressive stress state, the strain state is elongated in the axial direction. The three-way compressive stress state is favorable for improving the plasticity of the material, so that many difficult-to-process low-plastic materials can be formed or billet. When the amount of deformation of the material can be very large, can be done once squeezed into a material. Compared with other processing methods, extrusion molds easy to manufacture, easy to replace, easy to produce small quantities of multi-species products and complex cross-section of the product. The main drawback is that the unit pressure required for extrusion is higher than other processing methods, so the energy consumption is higher, the equipment is larger, the mold wears faster (see metal plastic processing).
As early as 1797, there was a patent similar to that of an extruded lead pipe manufacturing method. 1894 German Dick (G.A.Dick) first got the patent of the horizontal extruder, used to squeeze brass and other non-ferrous metals. 1905 ~ 1915 period has appeared in the 2000-ton large-scale extruder, and began to use heat-resistant steel mold. At present, the extrusion is mainly used for processing aluminum, copper and its alloys, in steel and rare metal processing has also been applied.
According to the direction of product outflow classification, extrusion can be divided into positive and anti-extrusion. The direction of the extrusion bar when pressing is the same as the direction of the metal flow, and the reverse extrusion is reversed. By temperature classification, extrusion can be divided into hot extrusion, cold extrusion and temperature extrusion. It is generally believed that the billet is heated above the recrystallization temperature during hot extrusion; the cold extrusion temperature is below the recovery temperature, usually at room temperature; the temperature range above the recovery temperature and below the recrystallization temperature is the temperature extrusion. Hot extrusion and cold extrusion are two major branches of extrusion. Temperature extrusion development is relatively late, the application range is also small.