| Electric motors are widely used in various fields of modern society,and they are one of the most important power equipment in national economic development and daily life.At present,the motor power consumption accounts for about 60%of the total electricity consumption in our country.Therefore,to improve the efficiency of the motor are of great significance for the promotion of energy conservation,environmental protection and sustainable development.The traditional cast aluminum rotor is an important part of the motor power loss,which seriously restrict the improvement of motor efficiency.Therefore,reducing the power loss of the rotor is an important way to improve the efficiency of the motor.As we all know,copper has excellent electrical conductivity,heat dissipation and wear resistance.When replacing the aluminum rotor with the copper rotor in an electric motor,the motor can has the advantages of low temperature rise,low loss,high efficiency,easy structure design,small vibration and low noise.Thus,the use of cast copper rotor has become one of the effective measures to develop ultra-high efficiency motor.As described above,the cast copper rotor has many advantages.But the casting temperature of copper is up to 1100℃ or more,and it can be a great test for the mold material and the chamber of die casting machine.In addition,the copper is easy to oxidize when smelting and has poor fluidity,which makes the die-casting production of cast copper rotor more difficult.This has also become the main obstacle to the widespread application of cast copper rotor.In response to the above problems,fluid simulation software FLOW-3D was used to realize the numerical simulation of copper rotor die casting process.And the orthogonal design method was used to optimize the key parameters of the die-casting process,which provided the theoretical basis for the design of the die-casting process.In this article,the main research work and achievements are as follows:(1)In this article,the cast copper rotor of electric motors was taken as the object of research,and a numerical simulation model of its die-casting process was established.Based on the FLOW-3D simulation software,the filling process of the die-casting was carried out.The flow field,the temperature field,the velocity field,the distribution of the gas entrapment and the surface oxide film in the flow process of copper melt were obtained in the simulation process.(2)Based on the numerical simulation method,the key parameters of casting process,such as filling temperature,pouring velocity and die temperature were studied.The impact of these parameters on the quality of copper rotor were obtained,which provided effective data and theoretical basis for the determination of die-casting process parameters.(3)The orthogonal test design method was used to search the best parameter scheme.A set of orthogonal tests including three factors and four levels were conducted.The filling temperature was selected between 1100～1250 ℃,the pouring velocity chosen between 30～45m·s-1,and the die temperature 250～400 ℃.The effect of parameter change on defect generation rate was analyzed,and optimal process parameter scheme were determined.(4)Based on the optimized process parameter scheme,we did the practical production and analyzed the microstructure of the die casting,getting copper rotor with good surface quality,small internal voids and a little shrinkage defect.The experimental results were in good agreement with the simulation results. |
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