铸件/铸型边界模型对用于RT的凝固模拟精度影响的研究

在快速模具制造工艺 RT (Rapid Tooling)中 ,采用尺寸凝固模拟技术保证铸件的尺寸精度是 RT工艺中关键的技术环节 ,而凝固分析中铸件 /铸型边界模型的正确与否对尺寸凝固模拟精度有着重要的作用。采用 3种不同的铸件/铸型边界模型对 RT工艺中典型标准件的凝固过程进行数值分析及实验验证 ,分析结果及实验证明在 RT工艺铸件尺寸精度的凝固分析中 ,铸型 /铸件的边界模型采用铸件、铸型均为热变形弹塑性体 ,且采用接触力学中的接触单元法对铸型 /铸件的边界进行分析更符合实际。采用这种铸件 /铸型边界模型对汽车覆盖件模具的凝固过程进行了热力耦合分析 ,数值计算得到的铸件尺寸与实际铸件的尺寸吻合较好 ,证实所采用的铸型 /铸件边界模型是正确的、可行的

Influence of boundary model between casting and mold on the accuracy of numerical simulation for rapid tooling

In Rapid Tooling, guaranteeing the dimensional accuracy of the casting die is a key technical problem for RT technology. The boundary model between casting and mold directly influences the accuracy of the numerical simulation of solidification for rapid tooling. Three different boundary models are adopted to analyze the solidification process of a typical part with the simulation results compared with experimental results. The comparison between simulated and experimental results indicates that the contact boundary model used in this paper is more accurate for numerical simulation of dimensional accuracy for solidification processed in rapid tooling. The boundary model assumes that both the mold and the casting are thermally elastic plastic deformable bodies and analyzes the boundary problem using the method of contact elements. This boundary model was used for a coupled thermo mechanical analysis of the die of an automobile deck part. The simulation result matches well with the practical casting further demonstrating that the contact boundary model used in this paper is accurate and feasible.