The early development process of extrusion technology is from soft metal to hard metal, from manual to mechanized, semi continuous, and further to continuous. With the continuous development of new engineering materials and the pursuit of high material utilization, modern extrusion technology will be further developed.
Classification and characteristics of extrusion methods
The classification of extrusion is also different according to the stress-strain state, extrusion direction, lubrication state, extrusion temperature, extrusion speed, type or structure of tools and dies, shape or number of blanks, etc.
According to different temperatures of ingots, they can be divided into
(1) Cold extrusion extrudes the ingot at room temperature.
(2) Warm extrusion heats the ingot to an appropriate temperature range below the metal recrystallization temperature for extrusion.
(3) Hot extrusion heats the ingot to an appropriate temperature range above the metal recrystallization temperature for extrusion.
According to different types of blank materials, it can be divided into non-ferrous metal extrusion and ferrous metal extrusion.
According to the extrusion method, seamless alloy pipe can be divided into forward extrusion method, reverse extrusion method, lateral extrusion method and hydrostatic extrusion method.
Generally, the extrusion in which the outflow direction of the product is the same as the extrusion movement direction during metal extrusion is called forward extrusion. The basic feature of forward extrusion is that the product has a wide range of dimensions, great flexibility and low investment cost. However, during extrusion, there is relative sliding between the blank and the extrusion barrel, and there is great external friction, which increases the extrusion energy consumption. At the same time, the temperature generated by friction makes the temperature of ingot uneven, resulting in uneven metal flow, which has an adverse impact on the quality of extruded products, resulting in uneven microstructure and properties of head and tail, surface and center of extruded products. In order to avoid cracks and other defects caused by uneven flow, the extrusion speed is reduced, resulting in reduced production efficiency.
During metal extrusion, the extrusion in which the outflow direction of the product is perpendicular to the extrusion movement direction is called lateral extrusion method, also known as transverse extrusion. The characteristics of lateral extrusion are: the axis of extrusion die and ingot is 900, the form of metal flow will make the difference of longitudinal mechanical properties of products small, the degree of deformation is large, and the extrusion ratio can reach 100. Due to its equipment structure and metal flow characteristics, lateral extrusion is mainly used for the forming of various composite conductors in wire and cable industry.
Post time: Jan-12-2022