High-speed Train Motor Magnet Wire Core Drawing Forming

With the development of railroad in our country, people pay more attention to the traction motor of the high speed train, The function of the electromagnetic wire, which is the key material for it then has been highly required. This kind of electromagnetic wire is made of high grade copper core heated at high temperature, with the kapton film or the FCR film in the surface, so it has excellent thermal conductivity, heat resistance, mechanical properties and electric properties. Compared with the overseas electromagnetic wire, Domestic electromagnetic wire is unable to meet requirements because of the copper core in the motor of the high speed train, differences exist in the aspects of the quality of the surface, dimension precision and flexibility. In order to improve the surface quality of copper core, three aspects researches about drawing equations, finite element numerical simulation and drawing experiments have been done in this paper. The text will describe it from three aspects:1. The application condition of the finite element simulation in the plastic deformation, basic principles, basic equations and solution method of rigid plastic finite element method were discribed; The rigid plastic finite element model of copper core was established, to chose feasible boundary Conditions of the model; and derive the mathematical fomulate of drawing copper core based on stress equilibrium differential eguation and plasticity condition.2. The commercial software, DEFORM-3D, was adopted to simulate the drawing forming test of copper core. The results indicate that:The distribution of effective stress, effective strain and temperature were uneven, with changes of four sides and rounded corner of copper core section were most remarkable. The conditions of friction had obvious in fluence on temperature, drawing load and metallic rheology during the drawing process, in the same conditions, lower friction could cut the temperature on processing interface, and made the temperature distribution more uniform, result in uniform deformation of copper core and lower drawiing strength. Process parameters could affect the metal rheology and stress significantly too, when drawing speed was under 1000mm/s and die angle keeps 8-10°, that were better conditions to reduce stress concentration, leaving the metallic rheology more uniform and surface quality improved.3. A drawing fixture that coordinated with universal tensile tester was developed, and copper core drawing experiments under different lubricant were carried out. The results of analysis show that:The effect was limited to reduced adhesive wear, cut drawing load and proved the surface quality just by increasing the viscosity of lubricant. Oiliness additive and extreme pressure addition was significant in reducing the friction during the drawing process, cuting the wear on the surface and production of copper powder, especially improving the surface of copper core.4. The contrast drawing experiment between fine oil-based lubricant and water-based lubricant was done to show that drawing force had been cut down by 900N when fine oil-based lubricant was used instead of water-based lubricant, Ra the roughness of surface was reduced from 1.30 to 1.10μm, micro-topography wsa more smooth, and surface quality was improved greatly, and clearly superior to existing electromagnetic wire industrial products (Ra=1.47μm). Sum up the above things, high-quality oil-based lubricant is one usefull key to the question of surface quality of electromagnetic wire core for high speed trains.