鑄件結構拓樸最佳化及其砂模鑄造方案設計之規劃

拓樸最佳化（topology optimization）是鑄件結構優化的一項技術，常見的結構優化有形狀最佳化（shape optimization）及尺寸最佳化（size optimization）等方法。本研究旨在利用數值方法進行合金鋼材料AISI4140鑄件結構之拓樸最佳化設計，再將拓樸最佳化設計後之鑄件結構規劃設計砂模鑄造方案。研究方法係使用商用軟體分析鑄件在成形過程中，熔湯的流動模式與鑄件的溫度變化情形，觀察可能產生的缺陷，並考慮鑄件臨界固相分率時間與材料密度兩項指標逐一討論，決定適當的澆道及冒口體積與其位置，反覆分析設計獲得最佳鑄造方案，以完成鑄件毛胚（raw casting）的設計。研究結果顯示使用拓樸最佳化方法可以在材料強度安全範圍內，獲得更加經濟之結構設計，且此方案設計流程非常適用於砂模鑄造前的毛胚設計，有助於減少模具開發的時間與成本，亦能有效降低鑄件縮孔缺陷。

關鍵字

拓樸最佳化；砂模鑄造；縮孔；臨界固相分率時間

並列摘要

Topology Optimization is a kind of structure optimization. The shape and the size optimizations are two common methods used in the structure optimization. Sand-casting is a casting method using sand as the mold material. In this study, the casting part made of AISI4140 alloy steel was optimized by using the topology method. A gating system for the optimal casting part was also designed. A commercial package was used to model the flow pattern and the temperature distribution in the casting part and to observe the possible defects that may occur, such as shrinkage porosity, during the casting process. The critical solidification time and the material density of the casting part obtained by the numerical analysis were then used to design the appropriate size of runner and the volume as well as position of the risers. After several iterations of simulation analysis, the optimal gating system design can be obtained, and the final casting design is then completed. The results show that the most economical structure based on the material strength within the safety can be obtained by topology optimization method. This design process would help to reduce the time and cost of the mold development, and also would effectively reduce the casting shrinkage defects, providing an efficient tool for casting design.

並列關鍵字

Topology optimization ； sand casting ； shrinkage porosity ； critical solidification time

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鑄件結構拓樸最佳化及其砂模鑄造方案設計之規劃

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