Yazar "Altan, Erhan" seçeneğine göre listele

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    Design of a computer aided quick-stop device for study of dead metal zone formation
    (Springer Heidelberg, 2012) Öztürk, Sabri; Altan, Erhan
    The use of quick-stop device allows observing a sequence of frozen images focused on the chip formation area when machining in orthogonal turning tests. This work records the development of a quick-stop device employing a servo motor. The present invention relates generally to a quick stop device, for combination with a cutting machine that is able to abruptly interrupt the cutting process between a cutting tool and the surface being cut. A dead metal zone is clearly seen when using rounded-edge cutting tools. In this study, variation of the dead metal zone is examined with the computer aided quick-stop device (CAQSD). It is clear from the experimental photomicrographs that as the cutting edge radius increases, dead metal zone increases.
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    Effect of work hardening of cobalt in sintered carbide cutting tool on tool failure during interrupted cutting
    (Springer London Ltd, 2017) Altan, Erhan; Uysal, Alper; Anaç, Şeref Han; Öztürk, Sabri
    In interrupted cutting, chips occur as intermittent and cutting tool may be damaged under severe variable loading. And it is known that the cutting forces cause transverse cracks on the rake face, and cutting tool may be damaged during interrupted cutting under mechanical and thermal fatigue in a short period of time. In this work, carbide inserts and forged SAE 4340 workpiece with axial slots were used in interrupted turning. The hardness values of some points on rake face near the cutting edge were measured, and cracks and failures on cutting tool were displayed by scanning electron microscopy (SEM). Additionally, milling experiments were conducted with carbide inserts on C45 medium carbon steel. In the interrupted cutting, the effect of work hardening of cobalt in sintered carbide cutting tool on tool failure was investigated. According to the results, micro hardness of sintered carbide cutting tool increased due to work hardening of cobalt, and this caused the micro crack formation on cutting tool.
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    An experimental study on dead metal zone in orthogonal cutting with worn rounded-edge cutting tools
    (Inderscience Enterprises Ltd, 2015) Uysal, Alper; Öztürk, Sabri; Altan, Erhan
    A dead metal zone is formed by the negative rake angle effect of the rounded-edge and it affects the cutting forces during machining operations. Therefore, investigating the size of the dead metal zone and changing it with cutting edge radius and flank wear rate are important. In this study, the dead metal zone was investigated experimentally for unworn and worn rounded-edge cutting tools and it was defined by changing the flank wear rate and cutting edge radius. It was observed that the size of the dead metal zone increased with increase of the cutting edge radius and it became smaller with increasing the flank wear rate. In addition, cutting force and thrust force were investigated. It was proven that both forces increased with increase of the cutting edge radius and the flank wear rate.
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    Metallographic analysis of the dead metal zone in metal cutting with a rounded-edge tool
    (De Gruyter, 2013) Öztürk, Sabri; Uysal, Alper; Altan, Erhan
    The experimental results show that a small dead region is seen in front of the rake face during cutting with a rounded-edge cutting tool. Although this fact was accepted, metallographic analysis of the dead metal zone had never been conducted. A quick stop device was used to obtain chip root samples that are representative of the deformation taking place during dynamic (actual) cutting conditions. A metallographic analysis was performed on selected specimens to identify the microstructure and formation. The photomicrographs were analyzed and an effort made to explain the dead metal zone microstructure.
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    Metallographic analysis of the dead metal zone In metal cutting with a rounded-edge tool
    (Carl Hanser Verlag, 2013) Öztürk, Sabri; Uysal, Alper; Altan, Erhan
    The experimental results show that a small dead region is seen in front of the rake face during cutting with a rounded-edge cutting tool. Although this fact was accepted, metallographic analysis of the dead metal zone had never been conducted. A quick stop device was used to obtain chip root samples that are representative of the deformation taking place during dynamic (actual) cutting conditions. A metallographic analysis was performed on selected specimens to identify the microstructure and formation. The photomicrographs were analyzed and an effort made to explain the dead metal zone microstructure.
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    Position of the separation point in machining with a rounded-edge tool
    (Sage Publications Ltd, 2013) Öztürk, Sabri; Altan, Erhan
    In this article, the effect of separation point on metal flows and the behavior of the material in front of the tool face with a rounded-edge tool are experimentally examined. The character of metal flow near the rake face has obvious significance to the partial problems of the surface finish and accuracy. Analysis of variance is used to determine the most significant parameter for the separation point height from the machined surface. As the distance between the separation point and the machined surface increased, the cutting edge radius grew. It is demonstrated through experiments that the edge radius of the cutting tool affects the machining and material flow process.
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    A slip-line approach to the machining with rounded-edge tool
    (Springer London Ltd, 2012) Öztürk, Sabri; Altan, Erhan
    In this paper, a new slip-line model approach for modeling the orthogonal cutting process with rounded-edge tools and its associated hodograph are proposed. This model consists of eight regions, which include a dead region in front of the rake face of tool. Dewhurst and Collins's matrix technique for numerically solving the slip-line problem is employed in the mathematical formulation of the new model. The experimental results show that a small dead region is seen in front of the rake face of tool during cutting with a rounded-edge cutting tool. The unknown slip-line angle pair was solved depending on the force data obtained experimentally and variation of the subregions with cutting edge radius was determined. Cutting force, thrust force, and dead zone grow as cutting edge radius increases in cutting edge-radiused tools.
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    Slip-line metal cutting model with negative rake angle
    (Abcm Brazilian Soc Mechanical Sciences & Engineering, 2012) Öztürk, Sabri; Altan, Erhan
    A small dead region is seen in front of the rake face of the tool during cutting with negative rake. The lack of knowledge about the stagnant region in the cutting with negative rake requires researching new models. In this work, cutting mechanism of the metal cutting with negative rake angle tools and the stagnation zone formation were studied. A model was generated from the experimental work by usage of the Dewhurst and Collins' matrix technique for solving the slip-line problem numerically. This model was applied at negative rake angles from 0 degrees to -70 degrees. All slip line angles in the slip line model that consist of three regions were resolved with the help of the experimental data. Variation of the dead metal zone and slip line regions with negative rake angle was determined. Effects of the negative rake angle on the cutting and thrust forces were investigated according to the cutting speed.