| The high efficiency motors effectively reduce the loss of motor in energy conversion by optimization of electromagnetism,mechanism and other aspects of motors and by use of quality materials and advanced manufacturing processes.In this paper the high efficiency motors specially refer to die-casting copper rotor motors manufactured by use of high quality copper alloy materials and advanced process.The high efficiency die-casting copper rotor motors replace the traditional aluminum rotor motors and have improved energy efficiency by 30%～7%.The high efficiency die-casting copper rotors referred to in this paper belong to new material energy saving category.And they are innovative to popularize the important function parts of high efficiency and energy-saving motor as a key part of cage motor.According to the requirements of high efficiency,high strength and high conductivity of electric motors of some special fields(such as new energy vehicles and high speed trains),we continue to study systematically the materials of die-casting copper alloy rotors and their manufacturing process based on the technology of high efficiency motors with pure copper rotor.Thus the industrial technology ability will be set up for manufacturing high efficiency die-casting copper rotor motors in industrial scale,and for technology of high performance rare-earth die-casting copper alloys and rare-earth intermediate alloys.Thus the good foundation for the application of such die-casting copper rotors in industrial field has been laid.In order to meet the requirements of high strength and high conductivity for new energy vehicles and high speed trains,trace elements(Cr,Zr,RE)were added to the copper based rotor materials to carry out research to improve the operational performance of motors.Based on the background the following studies have been made by medium-frequency induction furnace and die-casting machine etc.:design and research and regularity exploration about the micro-alloying principle by adding different micro-alloying elements of Cr and Zr alloy into copper;Some Cu-Cr-Zr copper alloy rotors were manufactured and tested.The microstructures during casting,processing,die-casting,and aging were analyzed by electronic microstructure analysis(SEM,TEM),optical microscopy(OM),X-ray diffraction(XRD)etc.Their properties were studied.And the effects of Cr,Zr and RE elements upon pure copper structures were analyzed and explained from both point of views of theory and manufacturing process.The main experimental conclusions can be summarized as follows:1、The research on micro-alloying proportions has been set up.The micro-alloying effects were analyzed by adding trace Cr、Zr and RE etc into cathode copper.The compositions of copper alloy are controlled:Cr:0.1～0.5%;Zr:0.05～0.2%;RE:0.05～0.2%;Cu:the rest part.The compositions of alloys were continuously stable by controlling experimental conditions reasonably.And by adding RE the crystrals were fined and the strength was improved.Finally the optimized micro-alloying proportions were obtained.2、Melting was carried out by using precision melting and casting technology and by use of intermediate alloys of Cr and Zr and under appropriate conditions in certain proportions.The compositions of cast ingot can be controlled precisely and Cu-Cr-Zr alloy can be formed efficiently by adding Cr and Zr etc.Trace elements into copper melt and by reducing loss amounts of burning.A lot of melting and casting experiments have been made.Average ratio of metal losses of Cr and Zr were Cr<10%and Zr<15%and RE<22%respectively.The copper alloy structure finally obtained can meet the requirements.3、In the atmosphere environment,the motor rotors were manufactured by medium-frequency induction furnace with gas protection melting and die-casting machine.The anti-pulling strength and electrical conductivity of rotors alloy areσb=505MPa,σr=88.4%IACS · And after aging they are σb=523MPa,ar=90.9%IACS.Thus the die-casting rotor alloy can meet the requirements of high efficiency motors for its industrial applications. |
