Research On Hydro-turbine Blade Hot Die Forming And Numerical Simulation

Hydro-turbine blade is a key component of waterpower equipment. The hydro-turbine blade hot die forming technology is an advanced manufacturing method. The blade which is manufactured by hot die forming has many advantages compared with the"Casting-Shovel milling"blade and the CNC blade. It is in good shape, high quality, high mechanical performance and short production cycle. A brief introduction to the studying content and its results are as follows:The hot die forming of hydro-turbine blade and its key technical problems are introduced in detail. The key technical problems include the unbending of blade in hot plasticity status and the pressure center. A blade billet is obtained by using integrated geometry unbending method and finite element method unbending. The dynamic pressure center is also solved by using node-load method based on FEM. Meantime; the forming load is gained through the real-time tracking of Stroke-Load curve.A 3-D thermal-mechanical coupling FEM simulation model corresponding to the reality is set up for the hot die forming of the hydro-turbine blade. The 3-D FEA software DEFORM is used for numerical simulation of the blade hot die forming and the results have been obtained for deformed mesh, effective stress field, effective strain field, temperature field, velocity field, the status of contact area and stroke load curve at the end of hot die forming. Besides, the influence of effective stress, effective strain, and temperature under different velocity on the blade hot die forming process is obtained. The results reveal the laws of blade hot die forming.The maximum forming load is chosen as the optimal objective and the forming technology parameters are chosen as the design variables. By dint of Orthogonal experiment design and least square for nonlinear regression fit method, the multivariant nonlinear regression model between the objective function and the three design variables is established. Based on the above the model and direct-vision analysis of dummy Orthogonal experiment design results, the blade hot die forming technology parameters-velocity of top die is optimized. The optimal technology parameters-velocity of top die, which is 22.3mm /s, is obtained.