The Study On Improving The Life Of Hot Forging Die

Required part is obtained by hot extrusion in the condition that material is put into die model after it's temperature is heated higher than re-crystal temperature and that huge plastic deformation is produced by powerful pressure and velocity of a hot forging machine. Generally the process includes three steps that is heating metal, smoothing die, deforming material. In this cycle process invalidation of a die should be brought due to mechanic loading and thermal loading between die and workpiece. Familiar invalidation shapes include crack, wear, deforming, erode, fatigue in the condition of hot or mechanic loading, the most possibility invalidation region are suffer higher load and the region where no better lubricating and dispelling heat.In the hot extrusion process, the maximum temperature of the surface of the hot forging die and the distributing of temperature in the hot forging die has main effects on the invalidation of a die. The hardness should drop when the temperature of the surface increase. The size of a die changes when the temperature fluctuates. The die deform even crack due to repeated effects between extend and compress in die produces by repeated operation between die and cooling fluid.In present paper the surface temperature of the hot extrusion die of Universal Joints as an example was carried out under DEF0RM3D soft. Effects of the material temperature, frictional coefficient, the velocity of forging equipment and the original condition of dies on the surface temperature were investigated; The mathematical expression be given out by curve fitting the simulation result base on the polynomial least square method in Matlab to find out the rule. The result of the research here can provide reference for improving the life of hot forging die and optimizing the structure of surface of die.In order to increase the die life, proper heat treatment and surface treatment is the key. The softening of a die would be prevented by covering a crust layer on die surface to counteract effects of thermal diffuse. The coat of TiN by PVD method can not increase the life of die because it is too hard to match with original material with lower hardness, so duplex treatment method is put up that is the transition layer is created between the crust layer and original material to obtain proper hardness and structure so as to increase the capability of the coat of TiN. In present paper the hot extrusion die of Universal Joints as an example, the effects of duplex coatings with nitrification and thecoat of TiN with PVD method on the life of die was carried out.The demand for die would become stricter and stricter in the becoming future. In order to improve the life of die the demand for heat treatment and surface treatment would become higher and higher.