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    Design, Fabrication and Performance Tests of a Double-sided Sheet Hydroforming Test System
    (Natl Inst Science Communication-Niscair, 2023) Urmamen, Mustafa Kemal; Atas, Gurkan; Dilmec, Murat; Turkoz, Mevlut; Ozturk, Osman; Halkaci, Huseyin Selcuk
    In this study, a double-sided sheet hydroforming (DSH) test system, which contains dies, sealing, pressure intensifiers, and a control unit, has been designed, built, and tested. The hydraulic numerical control system, which is currently used, has been modified as afour-axis where parameters are forming pressure, back pressure, punch position, and blank holder force. A hydromechanical deep drawing press has been modified in terms of die and sealing. New sealing components have been used to prevent leakage during the forming process because one side of the sheet is exposed to the forming pressure, and the other side is exposed to both the back pressure and the moving punch. Performance tests have been carried out to determine the limitations and capacity of the system. After the performance tests, it has been concluded that; the higher forming rates all along the process curve, the higher the pressure and force differences. However, the resultant error of the corresponding points has been only higher at the beginning of the process curve. In addition, the higher slopes in process curves have increased the pressure and force differences. A conical industrial part has been deformed by using hydromechanical deep drawing and DSH processes to test the performance of the DSH press. The wrinkling defect that occurred in previous hydroformed parts has been reduced remarkably by using back pressure in the DSH process. As a result, a double-sided sheet hydroforming test press has been successfully designed and manufactured. Finally, this study provides technical knowledge and can be used as a guideline for the design and performance evaluation of similar manufacturing systems.
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    Öğe
    Numerical and experimental investigation of the effect of double-sided hydroforming process on wrinkling damage by optimizing loading curves with adaptive control
    (Springer London Ltd, 2022) Akay, Selahattin Burak; Halkaci, Huseyin Selcuk; Ozturk, Ekrem; Ozturk, Osman; Atas, Gurkan; Aydin, Mevlut; Turkoz, Mevlut
    In this study, by using the double-sided hydroforming process (DSHP), scientific studies have been conducted to reach the highest formability possible with today's technology in deep drawing at room temperature and to produce difficult-to-shape parts. For the first time, the type-2 fuzzy logic controller (T2FLC) working with adaptive finite element analysis (aFEA) was applied to the DSHP, with the expectation that it would be a satisfactory solution to problems such as wrinkling, especially in the production of parts with different cross sections in the direction of the axis. In the literature, no study was found in which adaptive finite element analysis (aFEA) integrated with fuzzy logic control algorithms and genetic algorithm was applied to the DSHP to obtain the optimum back pressure profile. T2FLC was developed for the conical workpiece, and the variables used in the cylindrical workpiece were used first. DSHP is modeled with finite element method, and fuzzy logic algorithms have been developed to provide adaptive control in analyses. Using the aFEA-FLC optimum loading profiles also internal pressures and blank holder force loading profiles were determined. DSHP experiments were performed by the optimum loading profiles, and manufactured part geometry was compared with the part manufactured by non-applied back pressure in the sheet hydroforming process. By using the loading profiles obtained sheet metal parts have been successfully shaped numerically and experimentally without wrinkling or any other damage. It has been observed that as soon as the back pressure is applied, the wrinkling disappears, and the parts can be formed completely. It was concluded that DSHP is more effective than other hydroforming methods in terms of preventing wrinkling in axisymmetric parts with variable cross section.