Advances in Abrasive Technology XIV

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Authors: Ekkard Brinksmeier, J. Eckebrecht, A. Wilkens
Abstract: The chip removal process in grinding is characterized by intensive friction and plastic deformation leading to the risk of thermal damage of the surface-layer of the machined part. Thus productive and reliable grinding processes need effective monitoring. The difficult to access contact zone between the grinding wheel and the workpiece led to extensive research work on the temperature measurement in the grinding arc. In order to develop a tool integrated temperature monitoring system a new approach was undertaken which makes use of the measurement of infrared-radiation to monitor the temperatures in the grinding arc. The presented research work shows promising results suitable for an industrial applicable system for temperature measurement in grinding. The optical transmission of the infrared temperature information in combination with a fast detecting infrared sensor bares the potential to establish a highly miniaturized measuring system which is easy to integrate in any grinding wheel at comparably low production costs.
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Authors: Inigo Pombo, Jose Antonio Sánchez, N. Ortega, B. Izquierdo, S. Plaza
Abstract: Temperature measurement in grinding has been a widely analyzed field in the study of the process. Temperatures in grinding are too difficult to measure due to the high gradients in the ground workpiece. A lot of different methods have been employed by many researches in the last years. In this paper the use of thermocouples is analyzed attending to the mathematical characterization of their response. It will be shown that correct modeling of the thermocouple’s response permits the avoidance of the problem of thermal inertia, making thus possible the use commercial thermocouples for temperature measurement in grinding.
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Authors: Bei Zhi Li, Da Hu Zhu, Zhen Xin Zhou, Qiang Zhang, Yi Chu Yuan
Abstract: The temperature in cylindrical grinding contact zone is difficult for measurement. Relative to the fixed workpiece in surface grinding, the workpiece rotation in cylindrical grinding brings challenges to the temperature measurement. In grinding titanium alloy, more heat will be generated, and due to the poor thermal conductivity of this material, it is easy to make the high temperature rise in the grinding zone. The high surface temperature and its distribution along the depth of the workpiece have great impacts on the grinding burn, metamorphic layer and residual stress. In order to improve the surface quality of machined parts, based on the undeformed chip thickness, this paper proposed a quadratic curve heat flux distribution model to predict the surface temperature distribution in the grinding of titanium alloy (TC4). Experimental results showed that the quadratic curve model under the condition of the measured grinding power, can predict the temperature distribution in the cylindrical grinding zone. Meanwhile, it specifically discussed the impact of the wheel speed on the TC4 surface roughness and the stress distribution, and found the "high-speed" definition in high-speed grinding should be distinguished from the traditional way only judged by the wheel speed, different workpiece materials should be with different "speed" ranges for acquisition of better machining quality.
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Authors: Bei Zhi Li, Da Hu Zhu, Zhen Xin Zhou, Jing Zhu Pang, Jian Guo Yang
Abstract: The surface quality of workpiece depends largely on workpiece surface temperature in grinding. The key parameters on workpiece surface temperature calculation model have been researched and the calculation model constructed in this paper, including the convective heat transfer coefficient (CHTC) (hf), heat flux (qch) and the grain contact half-width (r0) which are assumed to be constant in workpiece surface temperature model given by Rowe. And the improved Rowe model has been proposed (Rowe/Li model) which not only involves the grinding process parameters such as the speed of wheel and workpiece, but also the geometric parameters of workpiece, grinding wheel and abrasive. The experimental results of the surface temperature in high-speed grinding are very close to the results by Rowe / Li model. Relative to the Rowe model, the obtained surface temperature by Rowe / Li model has decreased by about 35-40%. Under the conditions of the same material removal rate, high-speed grinding, namely, increasing wheel speed can effectively reduce the surface temperature and improve the grinding quality.
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Authors: Thai Nguyen, Liang Chi Zhang, Da Le Sun
Abstract: A three-dimensional finite element heat transfer model incorporating a moving heat source was developed to investigate the heat transfer mechanism in grinding-hardening of a cylindrical component. The model was applied to analyze the grinding-hardening of quenchable steel 1045 by two grinding methods, traverse and plunge grinding. It was found that the heat generated can promote the martensitic phase transformation in the ground workpiece. As a result, a hardened layer with a uniform thickness can be produced by traverse grinding. However, the layer thickness generated by plunge grinding varies circumferentially. The results are in good agreement with the experimental observations.
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Authors: Han Huang
Abstract: The machining of thin film multilayered solar panels is facing a great challenge in industry due to the low machining efficiency, and a timely solution is needed if this approach is to progress further. The successful employment of a new machining technology for the solar panels requires comprehensive understanding of the deformation and removal mechanisms of nanoscale multilayered materials, which has never been previously achieved. This paper reviewed the understanding of mechanics of nanoscale multilayer structures, and reported the recent progress on the development of abrasive machining technologies forthin film multilayered structures.
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Authors: Jan C. Aurich, M. Steffes
Abstract: This paper presents an overview of kinematic simulations in grinding. Up to now the simulations are carried out under the assumption of an ideal cutting process. Therefore, the simulation results are not exactly identical to the experimental results. For this reason, the simulation needs to be enhanced with the plastic material flow during cutting. To explain this behavior, single grain scratch experiments were conducted to detect the different sources of influence on the plastic deformation and on the pile-up. First, in the experiments the grain shapes as well as the cutting speeds were varied. To take the effect of different grain shapes into account, three different grains were used. The effect of the cutting speed was investigated at cutting speeds ranging from 60 to 120 m/s. The results were evaluated with a confocal microscope. To quantify the results of the efficiency of the cutting process, the relative chip volume parameter was used.
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Authors: Takazo Yamada, Michael N. Morgan, Hwa Soo Lee, Kohichi Miura
Abstract: It is considered that the contact stiffness between the grinding wheel and the workpiece depends on the number of the abrasive grains in contact with the workpiece and the support stiffness of a single abrasive grain. In this paper, the calculating method of the theoritical contact stiffness of grinding wheel in grinding operation was proposed. Comparing calculated results of the contact stiffness in grinding operation with measured it in the stationary state, the contact stiffness of the grinding wheel in grinding operation was investigated.
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Authors: Haruhisa Sakamoto, Kyoko Nakamura, Yoshinori Sasaki, Shinji Shimizu
Abstract: In this study, the determination method of the number of the effective cutting-edges had been proposed based on the measurements of working surface topography and the grinding force. Furthermore, its validity is made clear based on the topographical analysis of the ground surface roughness of pure copper, which is excellent in transcribing the working surface. From the results, the following are found out: The ground surface topography contains the periodical component, which is originated in the grinding and dressing conditions, on the fractal noise component. The cutting traces by each cutting-edge can be countable from the ground surface profile, and then, the number of the effective cutting-edges is identified at one line within the working surface. On the other hand, the number of the effective cutting-edges also can be identified based on the working surface, but, this method requires the determination of the typical grain shape. From the experiment, it is confirmed that the grain shape should be almost spherical for making the numbers of the effective cutting-edge identified from the working and ground surfaces equal.
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