基于中弧线的叶片蜡模模具型面优化方法

Optimization of wax pattern die profile for turbine blade based on mean camber line

针对高精度复杂涡轮叶片成形精度难控制的问题,提出了基于叶型中弧线的蜡模模具型腔优化设计方法。对反映中弧线几何特征的参数进行提取与偏差分析后进行逆向迭代,经过对叶型的复原和对叶身的重构,建立优化的蜡模模具型腔,实现了对叶片凝固和冷却过程中非线性变形的补偿。与有限元法模具型腔逆向设计方法相比,无需后续复杂的曲面拼接和光顺技术。采用该方法对某型涡轮叶片蜡模模具型面进行优化,使铸件的尺寸误差得到了大幅度降低。数值模拟与实验结果吻合情况良好,经过4次迭代优化,得到的仿真铸件模型与设计模型的二维偏差平均值由优化前的0.350 94 mm降低至0.111 51 mm。

Aiming at the problem of complex turbine blade＇s shape accuracy was difficult to control,an optimization design method of wax pattern die profile for turbine blade based on mean camber line was proposed.The parameters describing the geometric characteristic of mean camber line were extracted and analyzed,and inverse iterative method was applied to the analytic results.The optimized wax pattern die profile was established by restoring the blade shape and reconstructing the blade body,and nolinear deformation compensation of the turbine blade in solidification process was realized.The post-processing of surface smoothing and surface patching was no longer needed as comparing to the reverse method based on Finite Element Method（FEM）.By studying the investment casting of a typical blade,substantial reduction in dimensional and shape tolerances was achieved with the proposed die shape optimization method.The numerical simulation tallied with experiment result.After four iterations,the two-dimensional mean deviation obtained form casting model and design model decreased to 0.11151mm from the previous 0.35094mm.