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Öğe Investigate the effect of pre-drilling in friction drilling of A7075-T651(Taylor & Francis, 2014-04-28) Demir, Zülküf; Özek, CebeliFriction drilling is a non-traditional hole achieving method that is a clean, chip-less process, which is called thermal drilling, form drilling, flow drilling, and friction stir drilling. In this study pre-drilling friction drilling was investigated for improving the bushing shape of A7075-T651, which is a brittle cast material. During the process, surface roughness and bushing shapes were analyzed and generated frictional heat was measured by the virtue of thermocouples. Experiments were carried out to 4mm and 6mm in thicknesses of A7075-T651 aluminum alloy at 1200, 1800, 2400, 3000, and 3600 rpm spindle speeds, 20, 40, 60, 80, and 100 mm/min feed rates with using high-speed steel rotating conical tool, whose diameter is 8 mm. Consequently, the bushing shapes were advanced without cracks and petal formation in pre-drilling Friction drilling in comparison with without pre-drilling process. With increasing pre-drilled hole diameter the generated frictional heat was decreased. The achieved temperature was realized to be 1/2-1/3 of the melting temperature of the workpiece. Surface roughness values were decreased with decreasing or increasing both spindle speed and feed rate correspondingly.Öğe Model and formulation in grinding mechanism having advanced secondary rotational axis(SAGE, 2019-04-15) Adıyaman, Oktay; Demir, Zülküf‘‘Grinding Mechanism having Advanced Secondary Rotational Axis’’ is one of the newer plane surface grinding methods that has an uncommon abrasion mechanism. Unlike conventional methods, in Grinding Mechanism having Advanced Secondary Rotational Axis, there are two rotations of a wheel. The first rotation is the same as the conventional grinding methods, which is the circumferential rotation. The other rotation is the newly developed axial rotation, where the wheel rotates around itself perpendicular to its radial axis. In the grinding process, the grinding force, energy, power, and temperature are directly related to the material removal rate. In this article, the chip model in Grinding Mechanism having Advanced Secondary Rotational Axis was addressed and material removal rate was reformulated. The new chip ratio formula was adapted to the grinding force, energy, power, and temperature in the conventional plane surface grinding method. The chip formed in the conventional plane surface grinding method consists of two-dimensional xy plane. In Grinding Mechanism having Advanced Secondary Rotational Axis, on the other hand, the chips consist of threedimensional xyz plane. The reason behind this is the second rotation obtained in Grinding Mechanism having Advanced Secondary Rotational Axis (axial rotational motion). The chip model was obtained from the combination of two rotations in Grinding Mechanism having Advanced Secondary Rotational Axis. As a result, the resulting chip model increased the material removal rate only slightly and this increase was negligible. Accordingly, an increase in grinding force, energy, power, and temperature was observed at negligible rates.Öğe An experimental investigation on bushing geometrical properties and density in thermal frictional drilling(Multidisciplinary Digital Publishing Institute (MDPI), 2018-12-18) Demir, Zülküf; Özek, Cebeli; Bal, MuhammedIn thermal friction drilling (TFD) operations, the geometrical dimensions of bushing shape, height and wall thickness are the most vital consequences, since these increase the connecting length and strength. In this paper, AA7075-T651 aluminum alloys with 2, 4, 6, 8, and 10 mm thicknesses were drilled with the TFD process in order to investigate density, volume ratio, and height and wall thickness of the bushings. The experiments were conducted at constant spindle speed and feed rate conditions by using High Speed Steel (HSS) conical tools of 5, 10, 15, and 20 mm in diameter. It was experimentally found that the bushing height and the wall thickness had a tendency to increase linearly with the increase in both material thickness and tool diameter. The effect of tool diameter was found to have more influence on the measurable values than the thickness of the drilled material. The density of the bushing changed trivially. Approximately 70-75 percent of the evacuated material formed the bushing shape in TFD operations.Öğe An experimental investigation of the effects of point angle on the high-speed steel drills performance in drilling(SAGE, 2018-11) Demir, ZülküfThe differences in the cutting speed are a serious problem along the cutting edge of the drill, in drilling operations. This problem can partly be solved reducing the length of the cutting edge via changing the drill point angle. In addition, in this study, the effect of point angle, feed rate, and cutting speed on drilling is investigated. For identifying the optimum cutting parameters, AISI 1050 steel alloy was selected as the experimental specimen, these specimen were pre-drilled 5 mm in diameter due to eliminating the effect of the chisel edge. In the experiments, the holes were drilled only at a depth of 10 mm in order not to give any harm to the dynamometer while measuring thrust force. For this aim, in drilling process, drills with point angle of 100°, 118°, 136°, 154°, and 172° were selected. In conclusion, the thrust force, the tool wear, and the surface roughness linearly decreased with increasing point angles due to less removal chip area, in per revolve of the tool. However, the thrust force, the tool wear, and the surface roughness were adversely affected at higher feed rates and lower cutting speeds. The hole dimensional accuracy decreased at lower feed rates and cutting speeds but at higher point angles and concurrently at higher feed rates but lower point angles and cutting speeds. However, the hole dimensional accuracy showed more decisiveness at 118° than other point angles, while the highest dimensional accuracy values recorded at 136° point angle, at higher cutting speeds.Öğe An investigation of the effect of parameters and chip slenderness ratio on drilling process quality of AISI 1050 steel(Hindawi, 2018-05-08) Demir, Zülküf; Yakut, RıfatThe chip slenderness ratio is a vital parameter in theoretical and applicable machining operations. In predrilled drilling operations of AISI 1050 steel alloy, HSS drills were employed, and the effect of the selected parameters on the chip slenderness ratio and also the effect of the chip slenderness ratio on the thrust force, surface roughness, drilled hole delamination, tool wear, and chip morphology were investigated. The major parameters, influential on the chip slenderness ratio, were feed rate and point angle, while spindle speed was too small to be negligible. With increasing the chip slenderness ratio, the thrust force and the tool wear decreased, which resulted in appropriate chip morphology, but there were increases in surface roughness. However, the chip slenderness ratio had no effect on the drilled hole delamination.
