Yazar "Demirci, H. Ibrahim" 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 Univ, Fac Engineering Architecture, 2014) Gok, Arif; Gologlu, Cevdet; Demirci, H. Ibrahim
    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 degrees to 60 degrees 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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    The theoretical and experimental investigation of blank holder forces plate effect in deep drawing process of AL 1050 material
    (Elsevier Sci Ltd, 2008) Demirci, H. Ibrahim; Yasar, Mustafa; Demiray, Kemal; Karali, Mehmet
    The plastic forming process of sheet plate takes an important place in forming metals. The traditional sheet plate forming techniques used in industry are experimental and expensive methods. Prediction of the forming results, determination of the punching force, blank holder forces and the thickness distribution of the sheet metal will decrease the production cost and time of the material to be formed. With this aim, firstly simulation was realized with taking the contact model, material specifications into consideration by using non-linear explicit finite elements method (ANSYS LS-DYNA). In the analysis, the effects of fixed blank holder forces on the wall thickness distribution and wrinkles were examined. As a result of the analysis, without the sheet metal wrinkling or exceeding the tearing limits, for smooth drawings of blank holder the required forces were determined. The results were evaluated and experiments were done with the forces which were determined earlier. As a result of the experiments, which were done with the results obtained with finite elements method, 90% consistency between the experimental and theoretic results was seen. (c) 2007 Elsevier Ltd. All rights reserved.