• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.8
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• pp.1910-1920
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• 1993

An experimental study to investigate the unconventional chip formation called triangulation of chip in cutting with a SPRT (self-propelled rotary tool) is performed using acoustic emission (AE) signal analysis. In doing that, a quantitative model of the AE RMS signal in triangulation with a SPRT is first developed. The predicted results from this model show good correlation between the AE RMS signal and the general characteristics of triangular chip formation. Then, effects of various process parameters such as cutting conditions (cutting speed, depth of cut, oblique angle and normal rake angle) and the work material properties on the chip formation in cutting with a SPRT are explored. Special attention is paid to the work material properties which are found to have significant effects on triangulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1789-1794
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• 2003

As a new approach to analyze shear behaviors in the shear plane and chip-tool friction behaviors in the chip-tool contact region during an end milling process, this paper introduces a method to transform an end milling process to an equivalent oblique cutting process. In this approach, varying undeformed chip thicknesses and cutting forces in the up-and down-end milling process are replaced with the equivalent ones of oblique cutting. Accordingly, in the current paper, the shear and friction characteristics of end milling operations, up- and down-end milling, have been analyzed based on the equivalent oblique cutting models. Two series of cutting tests, up- and down-end milling tests and the equivalent oblique cutting tests to that, have been carried out to verify the validity of the analyses. And using the results of cutting tests the cutting characteristics of the up- and down-end milling processes have been thoroughly investigated.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.252-261
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• 1988

Through the careful interpretation of the results of the cutting tests carried out in this study, it is found that under the cutting conditions when the internal shear of the chips take place the cutting can be treated essentially as a steady state problem. A new shear angle equation has been developed employing the conditions of force and moment equilibrium about the tool edge and the stress distribution model suggested by Zorev.The equation contains the chip-tool contact length C and stress distribution index n as important parameters.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.223-228
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• 2003

In end milling processes, characterized by use of rotating tools, the underformed chip thickness varies periodically with the phase change of tool. In current study, as a new approach to analyse shear behaviors In the shear plane and chip-tool friction behavior chip-tool contact region during an end milling process. In this approach, an up-end milling process is transformed into an equivalent oblique cutting process. Experimental investigations for two sets of cutting tests i.e.. up-end milling and the equivalent oblique cutting test were performed to verify the presented model.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.887-890
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• 2001

In end milling process the underformed chip thickness and the cutting force components very periodically with phase change of the tool. In this study, up end milling process is transformed to the equivalent oblique cutting. The varying underformed chip thickness and the cutting force components in end milling process are replaced with the equivalent average ones. Then it can be possible to analyze the chip-tool friction and shear process in the shear plane of the end milling process by the equivalent oblique cutting mode. According to this analysis, when cutting Inconel 718.61% of the total energy is consumed in the shear process and the balance is consumed in the friction process.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.724-729
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• 2000

In end milling process the undeformed chip thickness and the cutting force components vary periodically with phase change of the tool. In this study, up end milling process is transformed to the equivalent oblique cutting. The varying undeformed chip thickness and the cutting force components in end milling process are replaced with the equivalent average ones. Then it can be possible to analyze the chip-tool friction and shear process in the shear plane of the end milling process by the equivalent oblique cutting model. According to this analysis, when cutting SM45C steel, 72% of the total energy is consumed in the shear process and the balance is consumed in the friction process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.10
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• pp.1520-1527
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• 2001

In end milling process the undeformed chip thickness and the cutting force components vary periodically with phase change of the tool. In this study, up end milling process is transformed to the equivalent oblique cutting. The varying undeformed chip thickness and the cutting force components in end milling process are replaced with the equivalent average ones. Then it can be possible to analyze the chip-tool friction and shear process in the shear plane of the end milling process by the equivalent oblique cutting model. According to this analysis, when cutting SM45C steel, 72% of the total energy is consumed in the shear process and the balance is consumed in the friction process.

• Journal of the Korea Safety Management & Science
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• v.4 no.2
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• pp.223-235
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• 2002

This paper presents some indirect physical evidences indicating that reduced friction occurs in an economical cryogenic machining process, in which LN2 is applied selectively in well-controlled jets to the localized cutting zone. These evidences include cutting force components, tool wear rate and chip morphology. LN2 reduced the tool wear rate to a great extent and elongated the tool life up to four times compared to emulsion cooling. The friction reduction was further reflected in larger shear angle and less secondary deformation in the chip microstructures. This study also found that the effectiveness of LN2 lubrication depends on the approach how LN2 is applied.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.902-906
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• 2000

In end milling process the undeformed chip thickness and the cutting force components vary periodically with phase change of the tool. In this study, up end milling process is transformed to the equivalent oblique cutting. The varying undeformed chip thickness and the cutting force components in end milling process are replaced with the equivalent average ones. Then it can be possible to analyze the chip-tool friction and shear process in the shear plane of the end milling process by the equivalent oblique cutting model. According to this analysis, when cutting SM45C steel. 82% of the total energy is consumed in the shear process and the balance is consumed in the friction process.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.10
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• pp.128-139
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• 1998

In this paper, a finite element method for predicting the temperature and stress distributions in micro-machining is presented. The work material is oxygen-free-high-conductivity copper(OFHC copper) and its flow stress is taken as a function of strain, strain rate and temperature in order to reflect realistic behavior in machining process. From the simulation, a lot of information on the micro-machining process can be obtained; cutting force, cutting temperature, chip shape, distributions of temperature and stress, etc. The calculated cutting force was found to agree with the experiment result with the consideration of friction characteristics on chip-tool contact region. Because of considering the tool edge radius, this cutting model using the finite element method can analyze the micro-machining with the very small depth of cut, almost the same size of tool edge radius, and can observe the 'size effect' characteristic. Also the effects of temperature and friction on micro-machining were investigated.