Analysis Of Factors Influencing Nealy Failure Of Warm Extrusion Die

Warm extrusion is one of new technology of finishing rough part between cold extrusion and hot extrusion, but at present one of the potential problem is bad early failure which is occured in its die. In order to put the new technology into practice, it is necessary to research generally on basic parameters and find prime factors of influcing die early failure during warm extrusion process.With the fast development of computer hard, finite element method and computer graphics, the computer aided engineering technology based on numerical simulation is used widely in metal plastic forming field, which actualizes computer emulation of metal forming process.In this paper, based on the detail reviews of the development of warm extrusion die at home and abroad, the forming process of warm extrusion of the yoke is simulated by DEF0RM-3D software with rigid-visco plastic finite element method, stress distribution in different stroke of male die is discussed, and variation law is researched of which the stress of die is increasing with the extrusion force increasing.In this paper, the influence of extrusion temperature, extrusion velocity and the temperature of die preheating to die failure are researched. The research has found that:1.The temperature field of workpiece is uneven during extrusion process. It is apparently higher in the part of smart distortion and contact friction with die than others.2.The reason of die failure is the plastic deformation and the crack because of rapidly cold and hot during extrusion process, when the load and stress is over its allowable load and stress .3.Extrusion force, the load of female die and die stress are bigger when metal overflowed die space and the flow direction of metal is opposite with the movement direction of male die.4. Extrusion force falls down, the stress of female die is low and the trend of plastic distortion is small when extrusion is over with extrusion temperature increasing; however, the higher the temperature of female die surface is, the bigger the trend of plastic distortion is fatigue because of cold and hot, the higher extrusion temperature is.5.The lower the temperature of female die, the smaller the trend of fatigue because of cold and hot, the faster extrusion velocity is; however, the higher the stress of female die is, the smaller the trend of plastic distortion is, the faster extrusion velocity is.6. The lower extrusion force is, the lower the stress of female die is, the smaller the trend of plastic distortion is, the bigger the temperature of die preheating is; however, the higher the temperature of female die surface is, the bigger the trend of fatigue because of cold and hot, the higher the temperature of die preheating is.Hereby, it provided a gist for establishing correctly precautionary technology about die early failure and improving die life.