Extrusion Press Mainly Subject To Deformation
Extrusion Press Mainly subject to deformation
In the extrusion process, the size of the extrusion force is mainly affected by deformation resistance, processing rate, billet length, die angle, extrusion speed, friction conditions, extrusion cylinder temperature and other factors.
One, deformation of the shape of the building
The deformation resistance of metals and alloys is a physical quantity that reflects their own strength properties. The magnitude of the deformation resistance has a direct effect on the extrusion pressure. When the other conditions are constant, the greater the yield resistance of the deformation resistance, ie, the greater the yield limit of the metal, the greater the required squeezing force. At high temperatures, the deformation resistance of the metal is reduced, so that the extrusion force decreases as the extrusion temperature increases. When the copper and copper alloy pipes are assembled on the vertical extruder, at other conditions (processing rate e = 90%, metal flow rate 480 mm / s; die angle a = 609; Change the situation, the squeeze pressure with the pressure of the relationship between the temperature.
Second, the processing rate of the impact of noon
The processing rate reflects the degree of deformation of the metal. When the other conditions are constant, the greater the processing rate, the greater the required squeezing force. Several copper alloy extrusion, the extrusion force with the size of the processing curve changes. In all cases, it can be seen that the extrusion force increases as the processing rate increases.
Third, the length of the billet effect
The length of the billet has a double effect on the extrusion force. The longer the billet, the longer the extrusion process, the greater the temperature drop at the end of the extrusion, thus increasing the resistance to deformation. In addition, when the length of the ingot increases, The friction between the billet and the extruded cylinder wall also increases, resulting in an increase in the pressing force. In the reverse extrusion, the squeezing force is independent of the growth.
Fourth, the shape of angle.
The angle a has a significant effect on the flow of metal. Under normal circumstances, the larger the angle a, Nil metal flow more uneven, so that the metal deformation work increased, squeezing force increases; the contrary, the angle A decreases, although the metal flow can be uniform, deformation Work down, squeeze pressure should be reduced. However, due to the metal and mold contact area to increase, but will increase the friction work, and the extrusion pressure increases. Therefore, the mold angle mouth only in the appropriate range to minimize the extrusion pressure. For the case where the round bar is squeezed with a round billet, the angle a is at 45-65. Within the best range.
The mold of the hole on the extrusion force also has a greater impact on the long length of the round bar longer, the greater the squeeze force.
Fifth, the impact of extrusion speed
In the practical application of the extrusion speed range, the pressure test shows that: when the extrusion speed increased by 2.5 times, the extrusion speed on the extrusion force has little effect. The squeeze pressure on copper alloy tubing is only increased by 10 x-15. However, the extrusion speed will change the extrusion time, which will eventually lead to changes in the strength of the extruded metal, resulting in a change in the extrusion force.
When pressing the IME bar alone, the extrusion speed increases from 70 mm l seconds to 970 mm / sec. At the beginning of the extrusion phase, the extrusion force increases significantly with the increase of the extrusion speed. The extrusion shaft is further advanced, and when the extrusion speed is low, the extrusion pressure is increased due to the cooling of the ingot. It can be seen that the low-speed extrusion "70 mm / s) of the billet than the high-speed extrusion of the ingot has a higher final extrusion force.