曲面嵌合應用於汽車鈑金回彈補正

Abstract

為了達到車身輕量化之目的，可以採用鋁、鎂合金等輕金屬來代替原材料，或是減少汽車鈑金厚度來達到其目的。但輕金屬價格居高不下，故各大汽車廠使用先進高強度鋼鈑為主。高強度鋼鈑相較於傳統鋼材具較高強度，因此可於碰撞法規要求下，適度減少材料厚度，而能夠達到車身減重目的。但高強度鋼鈑於沖壓製程中會產生嚴重的回彈情況，若仍以傳統方式透過試模、修模的補償方式，不僅增加模具開發的時間成本。 隨著電腦硬體開發，CAE軟體能夠模擬鈑金沖壓過程與預測鈑金的回彈量及補償。但CAE分析軟體預測的回彈補償分析輸出檔案為網格格式，需要再重建模面CAD檔案。本研究提出一套完整、有效率自動化重建補償曲面方法，透過輸入端的原始曲面與補償前、後網格三項資訊。首先依照原始曲面做分群，達到網格與曲面互相對應。接著透過原始曲面所提供的參數，利用最小平方法與平滑函數依序重建補償曲面。本研究提供重建曲面參數化調整，以及快速自動化重建，可以減少汽車廠開發時程，增加開發效率。

Using light metals like aluminum and magnesium alloys instead of raw materials, or reducing the thickness of automotive sheet metal can help achieve the objective of decreasing the weight of the car body. However, since the light metal prices remain high, advanced high strength steel (AHSS) is the main material for automotive sheet applications. High-strength steel, compared with traditional steel, possesses higher strength; therefore, by reducing the thickness of the material, high-strength steel can still be used to achieve the purpose of body weight loss in accordance with the collision regulations. However, a serious springback will occur during the high strength steel stamping process. By still applying the traditional method of compensation like mode trial and mode repairing will increase the time cost of mold development. With the development of computer hardware, CAE can not only simulate the sheet metal stamping process, but also predict the springback of sheet metal and compensation. However, the output of the springback compensation analysis by CAE software is in the mesh format, so it needs to be reconstructed as the CAD surface file. This study proposes a complete set of efficient and automated method to rebuild the compensation surface by entering the following three data: the original surface, the mesh before compensation and the mesh after compensation. First, the segmentation process is applied in accordance with the original surface to make the mesh and surface correspond to each other. Then, through the parameters of the original surface, the least squares method (LSQ) and smoothing function (Energy function) are put in use to rebuild the compensation surface in sequence, and thus complete the mold surface springback compensation process. This study provides the parametric adjustment on reconstruction of surface and the method of fast automated reconstruction, which can decrease the development time of automobiles and therefore increase the development efficiency.