Forging process of gear blank based on minimum damage value

In forging industry, in order to improve design efficiency, reduce manufacturing cost and improve product quality, it is necessary to optimize various process parameters affecting forging quality in forging process. The research on forging process parameter optimization started in the late 1980s. In the past, trial and error method was mostly used, that is, testing, calculation and comparative analysis through various process conditions, A more reasonable process scheme is optimized, but the amount of calculation and test is large, and it is not easy to obtain the best combination of process parameters. The damage value of material is a physical quantity reflecting the fracture tendency of material. According to the corresponding fracture criterion, when the material damage value of the deformed body reaches the critical damage value of the material, the material will fracture; For forgings, the smaller the damage value of the material, the smaller the chance of cracking during the use of the forging, and the fatigue life of the forging is also relatively increased.

Therefore, it is of practical significance to optimize the deformation process parameters based on the combination of finite element analysis technology and optimization technology to minimize the damage value of materials in the workpiece. In this paper, a forging process optimization method based on reduced descending gradient method is proposed. In the design process, the deformation process parameters are optimized by the combination of finite element analysis technology and optimization technology, The finite element analysis program deform is used as the solver for the objective function of deformation process in the optimization algorithm, which gives full play to the advantages of general finite element software and optimization algorithm to minimize the damage value of materials in the workpiece.

For the hot forging process of gear blank, the initial height diameter ratio of gear blank is an important factor affecting the quality of final forging. Improper selection of height diameter ratio will cause defects such as insufficient filling and folding of the final forging, as well as holes and material fracture in the forging. For the forging, the smaller the damage value of the material, the smaller the chance of cracking in the service process of the forging, and the fatigue life of the forging increases correspondingly.

To solve this problem, the reduced descent gradient method is combined with the finite element analysis method, and the finite element analysis program deform is used as the solver of the deformation process objective function in the optimization algorithm. Taking the height diameter ratio of gear blank as the optimization design variable, and the maximum damage value of all elements of forging (excluding flash part) is used as the index to measure the deformation damage of forging, Taking it as the optimization goal and taking the metal completely filling the cavity as the constraint condition, the optimization design of the initial shape of the gear blank in the hot forging process is studied, and the process parameter design is optimized. The optimized internal damage value of the final forging is small, and the cavity is completely filled, and obvious results are obtained.

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