Study On Precision Forging Of The EMU Steel Brake Disc

The steel brake disc precision forging of CRH2EMU was designed, precisionforging process of the steel brake disc and lessen ratio steel brake disc was numericalsimulated. The precision forging process test of lessen ratio steel brake disc wascarried out and development of steel brake disc precision forging was conceived. Themain research contents and conclusions are as follows:According to steel brake disc part, the parting face, draft, fillet and otherstructural elements of precision forging and flash groove of forging die were designed.By analysing material property, die material of steel brake disc should be selected5CrNiMo. The theoretical calculation of the forging hammer tonnage is36tons24tons. The theoretical calculation of deformation force on mechanical press is355593.7kN to288092kN. The theoretical calculation of deformation force on screwpress is199712.3kN to162123.8kN. The theoretical calculation of the deformationforce is189411.2kN according to Tot equation.The design of steel brake disc precision forging and its forging die wereoptimized by numerical simulation technology of DEFORM. The effect of processparameters of billet size, initial forging temperature, friction factor on precisionforging process of steel brake disc and lessen ratio steel brake disc were numericalsimulated. The best forging process parameters were determined. The numericalsimulation shows that, optimal billet size is Φ620×Φ340×67mm, flash thicknessshall be designed12mm. With increasing of the initial forging temperature,deformation force of steel brake disc decreases. With decreasing of the friction factorbetween top die, bottom die and billet, deformation force of steel brake disc reducesgradually, the maximum effective stress decreases gradually, the difference of effectivestress shows a trend of decrease. When preheating temperature of die is200℃,loading speed of upper die is500mm/s, initial forging temperature is1180℃, thefriction factor between top die, bottom die and blank is0.2, deformation force of steelbrake disc is168960kN. Φ320×Φ170×30.6mm specification of the billet is the most beneficial to precision forging of lessen ratio steel brake disc. When preheatingtemperature of die is200℃, loading speedof upper die is500mm/s, initial forgingtemperature is1180℃, the friction factor betweentop die, bottom die and blank is0.2,deformation force of lessen ratio steel brake disc is42720kN.The lessen ratio steel brake disc precision forging was successful trial-produced.After heat treatment of lessen ratio steel brake disc precision forging, its tensilestrength is more than1160MPa, stipulated non-proportional extension strength is morethan1080MPa, elongation is more than14.5%, reduction of area is more than61.5%,impact absorbing energy is more than85J. They meet mechanical performancerequirements of steel brake disc for EMU.The development assumption of the steel brake disc precision forging wasproposed. When billet size is determined, the radial-axial ring rolling billet makingprocess shall be adopt. The quality control was discussed, such as decreasing theoxidation and decarburized layer, forging die preheating, trimming and punching anddie forging cooling.