Research And Simulation Of Isothermal Forming Process Based On Induction Heating

The particle reinforced aluminum matrix composites have the characteristics of high specific strength and stiffness,good abrasion resistance,fast heat conduction but poor plasticity.The micro-structure changes in the deformation process is difficult to control,and long heating time will lead to coarse grain,micro cracks and inter-facial de-bonding defects,so a success deformation processing requires high quality of heat control.The isothermal forming technology keeps the work-piece's temperature of the best forming temperature range by heating the die to the same temperature as the work-piece,thus making its deformation more uniform,and the performance of the formed parts better,compared to that in traditional forming method.However,the production efficiency of the isothermal forming process is usually low for that its equipment is mostly heated with resistance furnace,which has limited its wide application in industry.In order to study the heating process of intermediate frequency induction heating process for isothermal forming,the induction heating experiments were carried out with 45steel and TiB₂/7075 aluminum matrix composite.The temperature evolution curves of two kinds of materials at different heating power were obtained.The temperature evolution of specimen during induction heating was simulated using software Marc,and two factors?current frequency and current density?affecting the temperature of the specimen were studied.After that,the local isothermal induction heating processes were studied.By adjusting the heating power and time,the specimen can quickly be heated up and preserved for a period of time,so as to achieve an isothermal state.On this basis,the local isothermal compression tests of 45 steel and TiB₂/7075 aluminum matrix composite bar were carried out.The induction heating and local isothermal forming of 45 steel were simulated in Marc.The simulation results agreed well with the experimental results.The isothermal forging process of a compressor blade of TiB₂/7075aluminum matrix composite was simulated using an finite element software Deform-3D,three main factors?forming temperature,forging speed and friction coefficient?affecting the forming quality of the blade were considered.Through the analysis of effective stress and effective strain distributions over the blade during forming process,it is found that when the forging temperature increases,the effective strain distribution of the blade is basically unchanged,and the effective stress and the die load decreases;when forging speed decreases,the deformation of the blade is more uniform,and the effective stress and die load decrease;when the friction coefficient increases,the effective strain distribution of the blade is basically unaltered,the effective stress distribution shows different patterns in different parts of the blade.Therefore,the deformation resistance of the blade can be significantly reduced by increasing the forging temperature,or reducing the forging speed and the friction.A new type of isothermal forming mold based on intermediate frequency induction heating was put forward to improve the heating speed,The mold has high heating efficiency,thus improving the production efficiency of isothermal forming;The use of standard mold and replaceable forming module low the mold cost and give it a strong versatility.