Equipotential-field Simulation And Preform Design In Materials Processing Engineering

Pre-forging design is one of the most important content in the forging technics design. Because the shape of pre-forging die and pre-forging are directly correspond with the one of finish forging, it limits the flow of metal, so the shape of pre-forging die and pre-forging effect on the final shape and the quality of finish forging. As far as the theory is concerned, for the certain shape of finish forging, the shape region of pre-forging is infinite. It is the duty for the optimum design to find best answer or close to the best from the infinite shape region. It is the key to produce eligible finish forging and one of the difficulties of die design how to design the shape of pre-forging and pre-forging die. At present, national and overseas works about pre-forging design most focus on the method of trial and error which utilizs numerical simulation technology to validate results, the validate method which is adopted is different from the traditional method of trial and error, but its essential idea is the same.Aim for the problem above, the paper further discusses the new design method of the pre-forging on the basis of equipotential field and forward simulation process with the existing research findings gained by our laboratory, and this method has been extended to idiographic forming technicas for simulation analysis. At the same time, a new method to take local smoothness treatment on the die cacity profile is put forward on the basis of Fourier transform according to the principle of spectrum analysis. The studied result is obtained.The main research findings and new outlooks are as follows:1. The possibility that simulating the materials forming process based on the similarity theory has been proved by equipotential field method, and general method and law which simulate materials forming process by equipotential field method is further discussed. The calculation method about the distribution of inner field variables is advanced and the visualization of the results is also put forward.2. The superplastic bulging technics of axisymmetrical circular sheets is researched by equipotential field method, the establishing process and method of theblank plas'ic deformation trajectory model is advanced when the die boundaries exist. Compared with the results of FEM. it shows that this method has the character of rapid calculation, reliable results and easy realization. The reasonable shape of preform and distribution law of field variables in forming process could be obtained by equipotential field method compared to the existent electrostatic field method.3. The equipotential field method is applied in the preform design of gear blank forming process, at the same time, a new method to take local smoothness treatment on the die cacity profile is put forward on the basis of Fourier transform according to the principle of spectrum analysis. Forging process of steel 45 gear blank with the pre-forging and finish forging is simulated, and correlative field variables of forging and die are analyzed, in conclusion, reasonable pre-forging die cacity profile is obtained. Forging process of gear blank with the pre-forging and without pre-forging is simulated and the results indicate that, compared with the forging without pre-forging, the maximal equivalent stress and equivalent strain of the forging with pre-forging minish, the transition region is more obvious and broader, the forming of materials is more even, the distribution and flow of materials are more reasonable, the performance of filling die is enhanced, so the possibility of preform design method on the basis of equipotential field method and local smoothness treatment method on the die cacity profile on the basis of Fourier transform is proved, and the reliability of their results also is proved.