逆止閥板金件預成形之有限單元分析與最佳化設計

Abstract

本論文在研究預成形製程，期望能對逆止閥板金件進行大量生產來降低成本。逆止閥為壓縮機的主要噪音源，經相關文獻得知逆止閥的幾何尺寸與開孔形狀均影響噪音值的大小。對本研究選定的逆止閥成品設計，應用預成形的方法進行對板金胚料的設計，藉由電腦的模擬取代人工設計所需的經驗及嘗試錯誤法的高成本。在研究中應用有限單元程式LS-DYNA3D來模擬逆止閥板金件的成形，並且藉由最佳化的方式，控制胚料開孔上的外形，把開孔的半徑當作設計變數，要求半徑差為最小時的預成形。在初步分析之後，開孔的外形有漸成圓形的趨勢，得到預成形的最佳組合。

The main objective of this research is to study the preform design of check valve in order to save the manufacturing cost of this product. As a major noise source of compressor, the check valve had been studied in the previous research and the best combinations of geometric parameters that give the lowest noise had been obtained. In the present study, the finite element code LS-DYNA3D had been combined with optimization code MOST to search for the preform design of a preselected check valve product made by sheet-metal drawing process. The shape of perforations on the blanked sheet was characterized by two radiuses that were treated as design variables. The minimum difference of these two radiuses after drawing was chosen as the object function in order to find the suitable preform that can result in circular orifices on the final product. A set of optimal values for the radiuses had been obtained through this research.