Optimal Design And Limit Size Analysis Of U-shaped Continuous Extrusion Die

At present,copper products are developing in the direction of high precision,high surface finish,and highly consistent performance;processes are developing in the direction of energy saving,environmental protection,and short flow.With the development of electronics,information and automobile industries,the demand for copper and copper alloy strips is growing.If copper processing enterprises want to achieve the goal of low-carbon emission reduction,U-shaped continuous extrusion can make the metal flow close to the same distance in a limited space to extrude products with a large width-to-thickness ratio.It is a manufacturing innovation of copper processing enterprises and conforms to the national the need for green development.Based on the TLJ630 continuous extruder,the pure copper rod with a diameter of 30mm was used as the blank,and the Hyper Xtrude simulation software was used to analyze the change law of product speed,temperature and block stress during the continuous extrusion of U-shaped copper material.By changing the cavity parameters,the influence on the mean square deviation of the flow velocity（SDV）at the exit of the die was studied,and the influence of different geometric parameters on the flow rate of U-shaped continuous extrusion products,cavity pressure,block stress and extrusion wheel torque were analyzed.Orthogonal test was designed,and the primary and secondary order of the influence of various geometric parameters of the mold on SDV was obtained,and the optimal mold design scheme was obtained.The function model of the contact stress in the mold cavity and the torque of the extrusion wheel was established by the analytical method,and the limit size that can be extruded was calculated.Finally,the calculation results were verified by the U-shaped continuous extrusion experiment.Using Hyper Xtrude software to simulate,the results show that:when the mold inclination angleαincreases from 22°to 28°,the SDV value and the stress of the stopper block gradually decrease;when the inclination angleβincreases from 12°to 20°,the SDV value gradually increases and the stress of the stopper block first increases and then decreases;the inclination angleθand the horseshoe bottom angleγhave little effect on the SDV value and the stress of the stopper block;when the height of the feed port h increases from 80mm to95mm,the stress of the stopper block gradually decreases.Through the orthogonal test,it is obtained that the primary and secondary order of each parameter affecting the mean square error of flow velocity isβ>α>θ>h>γ,and the optimal combination with the lowest mean square deviation of flow velocity is h₂α₂β₁θ₄γ₄;the primary and secondary order affecting the stress of the stopper block is h>β>α>θ>γ,the optimal combination to minimize the stress of the block is h₄α₄β₄θ₂γ₃.The U-shaped shape is optimized,and the optimal combination scheme is obtained as R₃θ₁h₃.The effect of geometric parameters on the U-shaped continuous extrusion process is analyzed by combining finite element simulation and theoretical calculation.The simulation results show that:with the increase of the thickness extrusion ratioλ₁,the SDV value increases significantly;when the diameter expansion ratioλ₂ is increased,the area with the fastest flow velocity shifts from both sides of the U-shape to the arc.The calculation formulas of the stress p_d of the U-shaped continuous extrusion block and the torque T of the extrusion wheel are obtained through theoretical calculation.Taking the stress of the block and the torque of the extrusion wheel as the judgment criteria,it is concluded that when the diameter d of the blank isΦ30mm and the flattened width b is 420mm,the limitable thickness t that can be extruded is 7mm.The continuous extrusion experiment of U-shaped copper strip was carried out.The experimental torque was compared with the theoretical torque,and the error was within 10%.