| The transmission-shaft is one of the most important parts in the SC6350 car of Changan automobile liability co ltd. The transmission shaft belongs to longer shaft and furcated parts which shapes are complicated and metal flowing in forming process is difficult. Previously no thorough study has been carried out on this kind of parts and the configuration of die used for manufacturing has not been optimized. Therefore, systematically and through research on the deformation process of transmission shaft and on the optimization of it form law is very important for die design and its process analysis via 3-D FEM simulation. A brief introduction to the project and its main results are as follows:A thorough study on the key technical problems of 3D rigid-viscoplastic FEM simulation of transmission-shaft hot forging process has been carried out and a 3D FEM simulation mechanics model corresponding to reality has been proposed. Simulation and analysis has been done using DEFORM3D developed by SFTC Corporation in USA. A series results such as the deformed mesh, velocity field, equivalent stress field, equivalent strain field, material damage and load stroke curve at various deformation degrees have been obtained. The research shows that its hot process consists of two working stages, which are preform and finish-form. On the process of preform, the distribution of stress and strain and local upsetting in top fields are largest and are extremely uneven; the deformation in the head is larger, and the deformation in the pole is smaller. On the process of finish-form, the deformation in the furcate fields is largest, the distribution of equivalent stress, equivalent strain, velocity and damage are different at various deformation degrees, which are divided into three phases and the distribution of the main variable are extremely uneven at same phase; the value of equivalent stress, equivalent strain and deformation are larger at bottom of the fork, at the same time, the values of equivalent stress, equivalent strain are smaller, but the velocity of deformation is larger on initial stage of forming. However, the values of equivalent stress, equivalent strain and damage are larger at furcate top on later period of deformation.Based on the trait and law of hot deformation of transmission-shaft, three kinds of finish-form punch are designed: the punch without restricts, the punch with plane restricts and the punch with cambered restrict. A simulation and analysis has beencarried out by using DEFORM3D for hot deformation process of finish-form punch with different configuration. The research shows that, the dimension of billet at least is Φ38×165㎜ for eligible products that are produced by using the punch without restrict; the dimension of billet at least is Φ38×158㎜ for eligible products that are produced by using the punch with plane restrict; the dimension of billet at least is Φ38×155㎜ for eligible products that are produced by using the punch with cambered restrict. On the other side, the break of load occurs in hot deformation process when using the punch with plane restricts. This will reduce the die's natural life. However, the problem can be overcame and the eligible products can be obtained when using the punch with cambered restricts. Other, the billet height can be reduced 10mm and 0.09Kg material can be saved per work piece when using the punch with cambered restrict. Besides, the thickness of top scrap is reduced half, so that the life of the trimming die is increased at least two times in the followed procedure.Based on the usual function frictional model, a simulation and study of an influence of friction along die-material interface on the hot deformation process of transmission-shaft has been carried out by using DEFORM3D. The results show: the deformation in billet pole is hardly affected by friction, but the deformation in fork field notably varies with various friction conditions. Taking one with another, the larger the friction factor, the metal flow reduced, the resistance and the loa...
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