金屬精微成形實驗規範之建立與尺寸效應機制之研究

Establishment of an Experimental Procedure and Analysis of Mechanism of Size Effect in Metal Micro Forming

丁永健(Yung-Cheng Ding)

指導教授 ： 陳復國

國立臺灣大學/工學院/機械工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.01569

摘要

金屬精微成形技術(metal micro-forming)是目前尚在起步階段的重要精密工業技術，具有成本低、生產效率高等優點，但當尺寸精微化時，材料之機械性質及摩擦特性將產生尺寸效應(size effect)而與巨觀下的表現不同，此效應將導致製程開發與應用上之困難。
故本論文以材料壓縮與拉伸機械性質之尺寸效應為切入點來進行研究，而目前並未有一套完整之對於精微實驗實驗規範可依循，本文先規劃精微實驗實驗規範之建立方法，再以C2720黃銅(Cu63 %、Zn37%)為實驗材料，完整地建立了C2720黃銅材料在精微尺寸下圓柱壓縮實驗及拉伸實驗之實驗規範，遵循此規範來進行精微實驗，其實驗結果來探討尺寸效應之機制才具有意義。接著以趨勢線定量分析法(curve fitting method)來分析所得之實驗結果，歸納出材料尺寸效應以及晶粒效應之經驗公式，以提供各界對於C2720黃銅材料之塑流應力曲線一套簡易之預測方法，並完整地建立C2720黃銅材料壓縮及拉伸實驗塑流應力曲線資料庫，將其置於本文附錄中以提供製程上之參考。最後，我們將觀察實驗試片之微結構的變化並配合微硬度實驗之實驗結果，探討經驗公式之理論模式，以完整瞭解尺寸效應之機制。本論文的成果提供精微金屬成形技術的製程開發上，一套評估材料機械性質之尺寸效應的方法，藉以用於未來改善缺陷之評估以及成形模具設計之參考。

關鍵字

金屬精微成形(metal micro-forming)技術 ； 尺寸效應(size effect) ； 精微圓柱壓縮實驗 ； 精微拉伸實驗 ； C2720黃銅(Cu63%、Zn37%) ； 經驗公式 ； 微硬度實驗

並列摘要

Metal micro-forming process is a developing technology in precision manufacturing. This technology has many advantages over MEMS, like lower cost, efficiently producing, etc. However, the material properties change obviously when the dimensions reduce to the micro level, such as stress and friction. The change because of reduced dimensions is called “Size Effect.” The effect results in the difficulty to begin with further research work.

The research on metal micro-forming has been developed more than ten years but not have a complete method including experimental and theoretical analysis. Hence, this paper is beginning on the literature survey, especially in the fields of micro test method and size effect to material properties. After collect and analyze the contents, we experiment several simplified tests to realize the influence of size effect. According to the experience of early tests and analysis of the relevant parameters, we propose the complete way to establish the experimental procedures in compression and tension experiment of micro specimens. The data from this process is trustworthy to research size effect.

In the study of size effect, we choose the C2720 brass material and get the compression and tension flow stress curve under different dimensions and grain size from experimenting. By using the curve fitting method to analyze the data, we can generalize an experience formula about size effect between dimension and grain size. The mechanism of size effect on compression and tension properties of C2720 brass material is completely investigated in this paper. In addition, we exhaustively discuss the feasibility of size effect with microstructure observing and micro Vickers’ hardness experiment.

並列關鍵字

metal micro-forming, size effect ； C2720 brass material ； curve fitting method ； experience formula ； microstructure observing ； micro Vickers’ hardness experiment

參考文獻

28. 蔡嘉文, “尺寸效應對材料硬度與界面摩擦之影響”, 國立台灣大學機械工程研究所碩士論文(指導教授：陳復國), 2003.

1. T. Jimma, and F. Sekine, “Precision Blanking of Electronic Machine Parts”, Advanced Technology of Plasticity, Berlinm Springer, pp. 291-297, 1987.

5. M.H. Fu, K.C. Chan, W.B. Lee, and L.K. Chan, “.Springback in The Roller Forming of Integrated Circuit Leadframes”, Journal of Materials Processing Technology, Vol. 66, pp. 107-111, 1997.

6. K.C. Chan, and S.H. Wang, “Theoretical Analysis of Springback in Bending of Integrated Circuit Leadframes”, Journal of Materials Processing Technology, Vol. 91, pp. 111-115, 1999.

7. Y. Saotome, K. Yasuda, and H. Kaga, ”Microdeep Drawability of Very Thin Sheet Steels”, Journal of Material Processing Technology, Vol. 113, pp. 641-647, 2001.