【作者】 杨云；

【导师】 王兆远；

【作者基本信息】 上海交通大学 ， 材料加工工程， 2008， 硕士

【摘要】 水轮机叶片是水力发电设备中的关键部件,叶片热模压成形工艺是叶片制造的先进技术。同叶片的“铸造-铲磨”方法和数控加工方法相比,叶片热模压成形具有很多优势:叶型准确、叶片内部质量好、机械性能高、生产周期短。本文的主要研究内容和结果如下:详细的介绍了叶片热模压成形工艺以及成形过程中的关键技术:叶片热塑状态的展开和压力中心及压力吨位估算。综合几何展开法和有限元展开法获得了叶片板坯;利用基于有限元的节点力法求解了动态压力中心,同时实时追踪行程载荷曲线,很好的估算压力吨位;建立了符合实际的叶片热模压成形的有限元力学模型,应用DEFORM有限元分析软件对哈电机的某水轮机叶片进行了三维的数值模拟分析。获得了叶片热模压成形过程中的金属流动情况、等效应力、等效应变、速度场和温度场的分布情况以及叶片模压的贴模状况和行程-载荷曲线,并分析了不同上模下压速度时的应力、应变、温度变化情况对叶片热模压成形的影响,揭示了叶片热模压的成形规律;以叶片热模压成形的最大载荷为目标,以成形的工艺参数-上模下压速度、摩擦系数和成形温度为设计变量,借助于虚拟正交试验和最小二乘的非线性回归拟合,建立了目标与设计变量之间的相关关系-非线性回归模型。基于该回归模型,在对虚拟正交试验进行直观分析的基础上,对叶片热模压成形的工艺参数-上模下压速度进行了优化设计,得到了最佳上模下压速度22.3mm/s。更多还原

【Abstract】 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.更多还原