Authors: Jing Shu Hu, Hong Min Pen, Yu Wang, Tao Chen, Zhen Chang, Xian Li Liu
Abstract: Air cooling is a near dry machining method, which cools cutting area and evacuates chip
using low temperature wind instead of cutting liquid. It can decrease tool wear, improve tool life,
reduce cost and produce no chemical pollution. In this paper, air cooling system is established, in
which vortex tube is used for cooling. Air cooling test was carried on, in which high hardness bear
steel GCr15 is machined by PCBN tool. Experiment results indicated that cold air from vortex tube
has a significant effect on cutting force, cutting temperature and chip formation process. Cutting
force and cutting temperature were simulated using Marc. Change rules that analysis results
indicated are in accordance with experiment results. This paper’s conclusions have a great reference
value for the practical application of air cooling technology.
369
Authors: José Vitor C. Souza, Maria do Carmo de Andrade Nono, Rodrigo de Matos Oliveira, M.V. Ribeiro, Olivério Moreira Macedo Silva
Abstract: During gray cast iron cutting, the great rate of mechanical energy from cutting forces is
converted into heat. Considerable heat is generated, principally in three areas: the shear zone, rake
face and at the clearance side of the cutting edge. Excessive heat will cause undesirable high
temperature in the tool which leads to softening of the tool and its accelerated wear and breakage.
Nowadays the advanced ceramics are widely used in cutting tools. In this paper a composition
special of Si3N4 was sintering, characterized, cut and ground to make SNGN120408 and applyed in
machining gray cast iron with hardness equal 205 HB in dry cutting conditions by using digital
controlled computer lathe. The tool performance was analysed in function of cutting forces, flank
wear, temperature and roughness. Therefore metal removing process is carried out for three
different cutting speeds (300 m/min, 600 m/min, and 800 m/min), while a cutting depth of 1 mm
and a feed rate of 0.33 mm/rev are kept constant. As a result of the experiments, the lowest main
cutting force, which depends on cutting speed, is obtained as 264 N at 600 m/min while the highest
main cutting force is recorded as 294 N at 300 m/min.
598
Authors: B.J. Xiao, Cheng Yong Wang, Ying Ning Hu, Yue Xian Song
Abstract: A two-dimensional orthogonal thermal-mechanical finite element model by Deform2D finite element analysis software is established in the article. By the adaptive meshing technique, not only cutting process but also the effect on the process of aluminum alloy Al6061-T6 processing as friction coefficient changing is simulated. The simulation shows that the friction coefficient has significant effect on the cutting temperature and cutting force, and the effect is nonlinear. With the increasing of the friction coefficient, the cutting temperature and cutting force will both increase. The impact the friction coefficient has on the surface residual stress is much smaller than the impact on the cutting temperature and cutting force.
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Authors: Pedro Jose Arrazola, A. Villar, R. Fernández, J. Aperribay
Abstract: This article describes a practical machining training aiming that the students acquire the theoretical-practical knowledge of chip formation process. The training takes place after theoretical lessons of machining processes. Thus, this practice allows strengthening the knowledge gained during the lessons. The practical training lasts for five hours, and the student assisted by the teacher analyses the influence of some machining entry parameters (cutting speed, feed rate...) on exit parameters like: (I) cutting forces and power consumption, (II) surface roughness, and (III) chip typology. The practical session is carried out on an experimental set-up (Lathe CNC Danobar 65) equipped with sensors and devices to measure forces (sensor Kistler 9121) and power consumption. In addition, a portable rugosimeter (Hommelwerke) is employed to perform surface roughness measurements. No especial devices are needed for the chip typology analysis. In the case of cutting forces and power consumption, the following input parameters influences are analysed: feed rate, depth of cut and cutting speed. In the case of surface roughness analysis, the following input parameters influences are analysed: feed rate and nose radius of the cutting insert. Finally, regarding chip typology feed rate and depth of cut are examined. The experimental results are compared with model predictions (theoretical calculations) for the three issues studied. The students have to compare both results: theoretical an empirical and they need to explain the reasons when discrepancies appear. Results obtained during the last years demonstrate the student acquires better knowledge of the machining process, and at the same time realises of the process complexity.
83
Abstract: Based on the engine lathe, the vibratory turning experiment system was built up with low frequency of the mechanical vibratory device. Orthogonal experiment was carried out for the findings of the chip configuration, chip breakage, and the surface roughness with relationship of the cutting engagement especially the combination of the vibratory frequency, amplitude, and the feed and cutting velocity. Regressive analysis was done for the empirical formula of the roughness with parameters of vibratory turning engagement. From the experiment it has been shown that the higher the frequency is in vibratory turning, the smoother the machined surface is, other conditions being equal. The surface roughness increases with the feed, at the same frequency. The cutting tool was still smooth on the rake and flank and along the cutting edges all the time in vibratory turning. Because of the vibration and the lubrication the BUE can hardly be built up, being good for the surface integrity.
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