Structure Design Of Shunt Bridge For Aluminum Profile Extrusion Under Ultra-high Speed And Low Extrusion Force

Aluminum alloy profiles have the advantages of light weight,high specific strength and easy recycling,It is widely used in various fields of the national economy.At present,the materials,die,processes and equipment technology of aluminum alloy profiles are basically mature.Except for some industrial profiles,most of the aluminum alloy profiles are conventional products.And the benefits of aluminum alloy profiles have become low.To achieve high-efficiency,high-quality and low-consumption manufacturing of aluminum profiles,high-speed extrusion(for example,reaching more than 4mm/s)or ultra-high speed extrusion is the future development direction.However,increasing the extrusion speed will result in a sharp increase in the forming load,which will accelerate the failure of the die.It is difficult to effectively increase the extrusion speed and reduce the forming force.The dissertation proposes to improve the design of the structure of the shunt bridge based on the principle of metal flow balance.The extrusion speed can be increased to high-speed extrusion or ultra-high speed extrusion,and the forming load can be effectively reduced,which is of great significance for further tapping the forming process potential to improve the benefits.After the improved design of the shunt bridge structures,the changes of the force on each key part of the die,the changes of the stress and deformation of the different shunt bridge structures during the extrusion process,and the selection of the optimal extrusion process parameters are the key issues.Focusing on the core problem of the design of the shunt bridge structures,the dissertation carried out the following studies,(1)The structure of the shunt bridge was improved.And the force of the extrusion die of the four key parts,such as forming area,the welding area,the shunt area and the upsetting pressure area was studied.According to the principle of metal flow balance,the extrusion die of curved parabolic shunt bridge structure was designed.The principal stress method was used to analyze the stress on the key parts of the extrusion die during the forming process.And the theoretical compression force on each key part was obtained.The force changes of curved parabolic shunt bridge and plane straight shunt bridge during the splitting of metal materials were analyzed.(2)The high-temperature rheological properties of 6063 aluminum alloy were studied.And the high-temperature rheological constitutive equation was established.Through thermal simulation experiments,the high-temperature stress-strain curve of 6063 aluminum alloy was obtained.The results showed that the flow stress of 6063 aluminum alloy decreased with increasing deformation temperature and increased with increasing strain rate.The key process parameters of the Arrhenius constitutive equation were solved by linear regression.And the high-temperature rheological constitutive equation of 6063 aluminum alloy was obtained.(3)The changing rules of the extrusion force,stress and deformation of different shunt bridge structures were analyzed.The influence of the key process parameters of extrusion forming on the extrusion die was studied.The results showed that the extrusion force of thecurved parabolic shunt bridge die was reduced by about 15.9% compared with the plane linear shape.The stable extrusion force was reduced by about 10.1%.The stress of the shunt bridge was reduced by 25.1%,and the deformation of the shunt bridge was reduced 21.7%.The ingot temperature has the largest influence on the extrusion force and the friction coefficient has the smallest influence.The optimal extrusion process parameters of the curved parabolic shunt bridge die structure were obtained.And the optimal parameters of the ingot temperature,the extrusion speed,the friction coefficient was 490 °C,6 mm/s,0.3,respectively.(4)The optimization effect of the shunt bridge structure was verified.Taking the building aluminum alloy profile extrusion die as the study object,a curved parabolic shunt bridge was used for the design of the die.And the optimal process parameters were used to verify the extrusion production of the profiles.The results showed that the actual production extrusion force of the curved parabolic shunt bridge extrusion die was from 10% to 20% lower than that of the flat linear shunt bridge extrusion die.The study results of the dissertation have theoretical and practical significance for the efficiency,quality,energy saving and consumption reduction level of aluminum alloy profile extrusion production.