Simulation And Experimental Study Of Continuous Extrusion Flow Characteristics

China is a country in the numerous production and consumption of copper alloy,so improving the quality and performance of copper alloy products is an inevitable choice for the further development of China's industrial economy,and more and more attention has been paid to the upgrading and optimization of its processing technology.As a non-ferrous metal processing technology,continuous extrusion technology is also an advanced processing technology for forming copper alloy wire,which has been widely used in industrial production.The quality of the continuous extrusion product depends on whether the metal flow velocity is uniform in the forming process.Therefore,it is of great theoretical significance and practical application value to study the flow characteristics to solve the problem of uneven metal flow velocity.Taking H62 brass alloy as an example,the physical simulation of forward extrusion,lateral extrusion,friction-driven lateral extrusion and continuous extrusion are carried out in this paper,so as to explore the influence of friction-driven mode on the flow rules of billet and lay a solid foundation for mastering the characteristics of continuous extrusion flow.The physical simulation can directly express the billet flow characteristics through the change of billet color.The results show that the metal shows different flow trends under different driving forces.With the forward extrusion driven by the rear end,the flow rate in the center of the product is the fastest,decreasing to the four sides,and the flow rate in the outermost part is the slowest..With the lateral extrusion driven by the side,the flow velocity in the center of the product is greater than that in the four sides,but the flow velocity under the product exit is greater than that above.The friction driving force of the friction driven side extrusion is discontinuous,and the flow characteristics of the product are similar to that of the lateral extrusion,but the billet will appear shear mixing phenomenon inside the extrusion cylinder.The friction driving force of continuous extrusion is continuous,the flow rate of the lower part of the cavity is higher than that of the upper part,and the billet of the lower part of the cavity flows upward,which affects the distribution of product organization.For physical simulation analysis of the different products of all kinds of extrusion and deformation temperature and deformation resistance,flow uniformity,this paper introduced the DEFORM and numerical simulation,the observed velocity field,temperature field,equivalent stress,equivalent strain field at the same time,emphatically analyzed the SDV values,the study found:extrusion product fastest velocity,the uniformity of the worst,the friction drive the slowest velocity,lateral extrusion products best uniformity.Among the round bar,square bar and six square bar with equal cross-sectional area,the flow speed of round bar is the fastest and the uniformity is the worst,and the flow velocity uniformity of square product is the best.Continuous extrusion experiments are carried out for the round bar,square bar and hexagonal bar with equal cross-sectional area.Bar products,for example,through physical simulation,numerical simulation and comparison metallographic organization chart,it is concluded that continuous extrusion metal flow characteristics:uneven metal flow velocity,the center of the cavity flow velocity is the fastest to reduce gradually,up and down on both sides of the asymmetric distribution of flow velocity is greater than the upper side under,near the mouth mould metal flow velocity is greater than near the extrusion wheel side,at the same time under the cavity side metal will appear over phenomenon;The dead zone of the transverse section of the cavity is in the shape of a ring,and the dead zone of the longitudinal section is in the shape of a triangle.The dead zone of the upper and lower sides is larger than the left and right sides,and the lower side is larger than the upper side.Billet extrusion phi phi8 mm to 5 mm round rods product experiment,die cavity section line in logarithmic function relation with quadratic function,the function relation between the cross-sectional die line for y=ln(2106.3 x-982.35),longitudinal and cross section function relation between the dead line for y=0.12 x~2+0.13x+0.29,through the definite integral computation,cross section dead zone area accounted for about 30%,longitudinal section of dead zone area accounted for about 11%.