金屬薄板液壓膨脹實驗結合成形極限之設備研發與研究

Abstract

為了能夠更便利、更準確並更完整地得金屬薄板的材料性質，如 薄板之應力-應變曲線(stress-strain curve)和成形極限圖(forming limit diagram)，本研究設計製作一整合的薄板材料實驗設備。首先建立液 壓膨脹實驗(bulge test)設備，取得薄板之應力-應變曲線，並與單軸拉 伸實驗做比較，驗證薄板液壓膨脹實驗之可行性。再以液壓膨脹實驗 設備為基礎，發展一金屬薄板液壓成形極限實驗。使用液壓膨脹實驗 的圓形模具，規劃不同的試片幾何，提出一使用橡膠做為液壓傳遞壓 力的概念，用以取得完整的成形極限圖，並與傳統的衝壓成形極限實 驗比較，驗證薄板液壓成形極限實驗之可行性。最後整合成一薄板材 料實驗之設備，以單一設備並更便利地取得應力-應變關係曲線與成 形極限圖。

To obtain sheet metal’s material properties such as stress-strain curve and fomring limit diagram. A more convenient and accurate apparatus of material test for sheet metal has been designed and manufactured. Firstly, a device of hydraulic bulge test was constructed to obtain the stress-strain curve and compared with that from uniaxial tension test to verify the feasibility of hydraulic bulge test. Secondly, hydraulic forming limit test was conducted based on a modified bulge test apparatus with a circular die. A new concept that using a PU layer to uniformly transfer the hydraulic pressure to the sheet matel was proposed so both the left side and part of the right side of forming limit diagram(FLD) can be obtained. And the limit strain of the right side of FLD under equal biaxial tension was also obtained after the bulge test. The complete forming limit diagram was then compared with that from traditional drawing test to verify the feasibility of hydraulic forming limit test. Finally, an integrated testing apparatus for sheet metal with capabilities to obtain both stress-strain curve and FLD has been completed and verified.