摘要

在過去板金成形極限的研究大多數應用於大型的工件上如汽車板金，但隨著工業產品的微小化，在建立FLD時，也要跟著蝕刻上細小網格，而在文獻中並沒有針對網格大小於板金可成形性的影響之探討。

本文以破壞能量準則來預測金屬材料之成形極限，並對材料進行可成形性試驗，以獲取實驗之成形極限圖，將理論所預測之成形極限圖與實驗所量測之成形極限圖互相比較驗證，以潤滑條件、網格大小、網格幾何形狀為變因，研究其對SUS304不銹鋼板金可成形性之影響。

本文以能量準則預測出成形極限，將能量準則所預測之FLD與實驗值比較，結果顯示相當吻合。由實驗得知以電化學方法蝕刻之網格大小極限約在400μm。以鐵氟龍潤滑可以比沖壓油潤滑下得到較高的FLD實驗應變值，得知以鐵氟龍潤滑可得到較佳的可成形性。網格越細小之FLD實驗應變值越大，危險與安全網格之極限應變帶越小，解析度越好。若網格越細小，則破壞應變能量常數越大。因此，蝕刻較細小的網格則能得到更接近真實的極限應變量。

ABSTRACT
In the past, most studies of forming limit of sheet metal were mainly for large-sized workpieces, for example, automobile stamping parts. Recently, more and more industrial products become small. When building the Forming Limit Diagram (FLD), it also needs to etch small grids. The literature rarely studied the effect of the grid size on sheet metal formability.
This study is based on fracture energy criterion to predict the FLD using the fracture strains from formability test. The predicted forming limit diagrams were compared with experimental data for different lubrication conditions, grid geometries and grid dimensions for SUS304 stainless steel.
The predicted forming limit diagrams by fracture energy criterion agree quite well with those by experiments. From the experiment, the limit of grid dimension was about 400μm by the electrical chemical etching method. It can obtain higher forming limit for Teflon lubrication than that for oil lubrication. It indicated that Teflon lubrication exhibits better formability. The smaller grid dimension, the higher forming limit is. The bounds between dangerous and safety grid is smaller, and the resolution is better for smaller grid. The smaller the grid dimension, the higher the fracture energy constant is. Therefore, the smaller grid can obtain limit strain closer to the real forming limit.

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