基于位移场仿真与特征参数提取的精铸模具型面逆向设计方法

 提出了一种简单高效的涡轮叶片精铸模具型面逆向设计方法:特征参数逆向调整法。一方面,基于叶片收缩变形位移场的有限元仿真结果,更为准确地计算铸件不同部位的收缩率;另一方面,通过12个反映叶型特征参数的提取、叶型的复原和调整技术,实现了凝固和冷却过程中非线性收缩变形的补偿,弥补了传统线性放缩法的不足。由于最终获得的型面仍然是参数化CAD模型,和单纯网格直接反向叠加法相比,无需后续复杂的曲面拼接和光顺技术。最后以叶片的叶身为例,将该方法与传统型面放缩法和网格直接反向叠加法进行比较,结果表明对于弦长为60.5mm的涡轮动力叶片,采用特征参数逆向调整法,叶型的型面误差、弦长误差和扭转角误差与传统的收缩中心放缩法相比分别降低了83.8%、96.3%和66.7%,因此具有很好的工程应用前景。

Reversing Design Methodology of the Die Profile in Investment Casting Based on the Simulation of Displacement Field and Identification of Featured Parameters

A simple and efficient reversing methodology of adjusting featured parameters is proposed for the casting-die profile design of turbine blades.On the one hand,casting shrinkages at different positions of the blade are considered as nonlinear thermo-mechanical casting deformations that are calculated with accuracy by finite element analysis.On the other hand,twelve featured parameters describing the camber line and thickness of the blade profile are identified,analyzed and adjusted to counteract blade deformations.This method therefore exhibits its advantage over the traditional linear scaling method.As the reversing design of the die profile is directly based on the CAD parameterized model,the post-processing of surface smoothing and surface patching is no longer needed as compared with the existing mesh-based reversing method.By investigating the investment casting of a typical blade with chord length of 60.5 mm,the proposed method is compared with the linear scaling method and mesh-based reversing method.Results show that the die profile obtained can satisfy the design requirement more accurately.Compared with the traditional linear scaling method,the maximum profile error,the chord length error and the twist angle error of the blade decrease by 83.8%,96.3% and 66.7%,respectively.