Progress of Precision Engineering and Nano Technology

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Authors: W. Li, Tong Xing, Bao Xiang Qiu, Gang Xiang Hu, Yang Fu Jin
Abstract: A reasonable finite element (FE) model of grinding temperature field has been developed on the basis of analysis of the transient temperature field, and three kinds of boundary conditions are loaded on the element of a moving heat source. The study, which is based on the finite element principle, has been carried out using the numerical simulation software ANSYS. Many results have been obtained including three dimensional temperature distribution map. The simulated results under different conditions show good agreement with the experimental results. With the comparison of the dry-grinding and wet-grinding, the result shows that the wet-grinding temperature with a proper grinding fluid is rather lower than the dry-grinding temperature. Finally, the variable coefficient of convective heat transfer and the different form heat source have been discussed in detail.
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Authors: Bao Ji Ma, Zhi Jian Fan, D.J. Stephenson
Abstract: Based on the concept of the interaction between a magnetic and electric field, a magnetic field was suppressed on the Electrochemical Machining (ECM) setup to improve the copying accuracy of ECM. Mathematical modeling and finite element modeling of the magnetic field was also developed using ANSYS to study the influence of permanent magnet design on the ECM process. The results indicate that by introducing the magnetic field the threshold of electrochemical reaction is decreased and the tracks of ions become complicated which makes the chemical reaction more extensive and more uniform in the inter-electrode gap. The distribution of magnetic field in the gap helps to improve the machining accuracy and the process efficiency, when the permanent magnet is at the end of the electrodes. Experiments have been carried out to validate the results of finite element analysis and the effect of a magnetic field on the ECM process is discussed.
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Authors: Hua Qiu, A. Kubo, Zi Ye Li, Chao Lin
Abstract: This paper proposes an optimal interpolation approach to generate cutter paths in the form of polar coordinate for machining noncircular contours. The cutter path obtained with the approach consists of a series of Archimedes’ spiral segments and the number of segments is the fewest under the condition that the interpolation error completely satisfies the specified limit value. It can be also evidenced that the profile error of the machined contour due to the cutter path is perfectly controlled within the specified interpolation accuracy limit. The result of applying the approach to the contour machining of a disc cam sufficiently illustrates the effectiveness of the proposed approach.
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Authors: Sun Kyu Lee, S.H. Jang, Seok Woo Lee, Hon Jong Choi
Abstract: The application of an ultrasonic vibration is one of promising means in machining micro-holes. In this study, the differences of in the geometric machining mechanism between the ultrasonic and the conventional drilling were investigated. Specifically, the uncut chip thickness before machining and the tool trajectories of the cutting edges were formulated and compared with machining results. Through the machining experiments, it was found that those these parameters well matched with the appearance of both the disposed chips and the machined surface. Furthermore, the results indicated that the change of uncut chip thickness resulted in decreased machining resistance as well as improvement of the machined surface
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Authors: H.X. Wang, Bo Wang, Jing He Wang
Abstract: In this work, a coupled thermo-mechanical plane-strain large deformation FE cutting model is developed to simulate diamond turning based on the updated Lagrangian formulation. As expected, the effects of friction coefficient on cutting forces, chip deformation, cutting temperature, flow stresses and shearing angle are investigated by FE simulations. The simulated results can be adopted as a reference to select the reasonable friction coefficient in diamond turning process.
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Authors: Jing He Wang, Shen Dong, H.X. Wang, Ming Jun Chen, Wen Jun Zong, L.J. Zhang
Abstract: The method of single point diamond turning is used to machine KDP crystal. A regression analysis is adopted to construct a prediction model for surface roughness and cutting force, which realizes the purposes of pre-machining design, prediction and control of surface roughness and cutting force. The prediction model is utilized to analyze the influences of feed, cutting speed and depth of cut on the surface roughness and cutting force. And the optimal cutting parameters of KDP crystal on such condition are acquired by optimum design. The optimum estimated values of surface roughness and cutting force are 7.369nm and 0.15N, respectively .Using the optimal cutting parameters, the surface roughness Ra, 7.927nm, and cutting force, 0.19N, are obatained.
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Authors: Ming Hai Wang, Ze Sheng Lu
Abstract: The mechanism of brittle-ductile transition (BDT) in machined Si single crystal is investigated by simulating dislocations emission from crack tip along (111) and (111) slip plane under mixed-mode loading. One kind of compression-shear crack is taken into account and the law of strain-energy-density-factor is applied as fracture criteria. The total number of the emitted dislocations and the number of dislocations in each slip plane at the onset of cleavage are calculated. It is found that the ratio of stress intensity factor kII to kI that the crack tip is subjected has significant effect on the BDT in machined Si single crystal. Then the results are applied to study the action of negative rake angle and edge radius of diamond tool in the ultra-precision turning.
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Authors: Tian Biao Yu, Ya Dong Gong, J. Liu, F. Xu, Wan Shan Wang
Abstract: A grinding wheel spindle with squeeze film damper—SFD is designed based on squeeze film damping theory and relevant grinding experiments have been performed. Experimental results indicate that the rationality of design for SFD can make the vibration of the grinding wheel spindle is reduced by 25%. The precision of hole machining is improved by 20%. At the same time, work efficiency of the grinder can be raised about 15%. So it has very important research value and wide application prospect in the field of machining.
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Authors: Song Zhang, Xing Ai, Jian Feng Li, Xiu Li Fu
Abstract: The HSK spindle/toolholder interface belongs to the complicated nonlinear contact problem caused by taper interference fit. The experiment and the traditional Lame's equation are all not suited for analyzing the contact stress distribution and deformation in the spindle/toolholder interface. In this paper, the contact stress distribution and the deformation of the HSK-A63 spindle/toolholder interface caused by the taper interference fit were precisely simulated by means of the finite element method. The simulated results showed that the toolholder shank was in partial contact with the spindle bore, the interference specified by ISO was not enough for the high-speed machining and larger interference should be introduced.
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Authors: Wen Jun Zong, Dan Li, T. Sun, K. Cheng
Abstract: In this paper, a coupled thermo-mechanical FE model is proposed to simulate the cutting temperature’s distribution produced in diamond turning. Simulated results indicate that the heat converting from plastic work has prominent effects on the distribution shape of cutting temperature field, and with an increment in cutting velocity, the locating site of maximal cutting temperature shifts from the contact area between tool tip and chip root to the contact area between rake face and chip. Cutting edge radius has minute influence on the distribution shape of cutting temperature field, but the bigger the cutting edge radius is, the higher the maximum cutting temperature in cutting region. Rake angle also has slight effects on the maximal temperature when it is more than 10○. While clearance angle reaches to 6○, the maximum cutting temperature approaches the smallest.
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