Yazar "Demirci, H.I." seçeneğine göre listele

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    Determination of form defects depending on tool deflection in ball end milling of convex and concave surfaces
    (Gazi Universitesi Muhendislik-Mimarlik, 2014) Gök, A.; Göloglu, C.; Demirci, H.I.
    Altering in surface forms cause to varying cutting forces in machining of inclined surfaces by ball end mills. The deflections appeared by cutting forces can result in form defects in workpiece. Finding deflection values and related form defects has a significant importance for keeping the production within the appropriate tolerances and in lessening production costs. The aim of this study is to evaluate form defects depending on tool deflection in milling of inclined convex and concave surfaces of EN X40CrMoV5-1/DIN 1.2344 using TiAlN-coated cutting tool. The experiments have been conducted with different cutting tools strategies and cutting parameters at related parameter levels. During machining real time cutting tool deflections are recorded by inductive sensors for the experiments. Then, the form defects of machined specimens caused by cutting tool deflections are determined by 3D optical scanning. The cutting tool deflection values and the values of 3D optical scanning form defects have been compared. The largest cutting tool deflections and form defects are detected at the ramping regions with the milling position angles of 45° to 60° for the convex and concave surface types. In addition, the regions that the largest tool deflections have been observed are the same regions with the largest form defects obtained by the optical scanning. As a result, at the determination of form defects caused by cutting tool deflection, the deflection values obtained by real time measurement are coincided with the measurement obtained from 3D optical scanning.
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    Investigating aluminum sheet wrinkling during the deep drawing process
    (Transactions of Famena, 2013) Foudeh, M.R.; Daneshmand, S.; Demirci, H.I.
    The purpose of this study is to consider the effect of different parameters on the wrinkling phenomenon of square cups during the deep drawing process. An experimental system was prepared which consisted of a hydraulic press capable of applying different loads on the sheet metal blank and a blank holder and the process was controlled by a computer. All simulations were performed by using the ABAQUS/EXPLICIT V6.9 software, and the effect of different aluminium alloys, punch and die radius, blank holder force, blank holder gap, and friction coefficient on the wrinkling phenomenon has been investigated. Moreover, the minimal blank holder force was obtained by plotting minor strain with respect to the major strain of produced cups, and obtaining the maximum height of wrinkle in a cup. The wrinkling phenomenon was further investigated on different alloys such as A6111-T4, AA5754-O and Al-1050. The results imply that increasing the blank holder force and friction coefficient on the one hand and reducing the blank holder gap, punch radius, and die radius on the other hand, may lead to a reduction in wrinkling during the deep drawing process. Nevertheless, under the same circumstances of the deep drawing process, the wrinkling of the A6111-T4 alloy is more significant compared to the Al-1050 and AA5754-O alloys, while the Al-1050 alloy needs less blank holder force to avoid wrinkling. Using this simulation program it is possible to easily simulate the wrinkling of sheet metal blanks with the least number of trial and error.