• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.12
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• pp.1185-1191
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• 2011

The kinematic characteristics of cutting device significantly affects cutting performance in 2-dimensional elliptical vibration cutting(EVC) where the cutting tool cuts workpiece, traversing a micro-scale elliptical trajectory in a trochoidal motion. In this study, kinematical characteristics of EVC device constructed with two parallel stacked piezoelectric actuators were analytically modeled and compared with the experimental results. The EVC device was subjected to step and low-frequency(0.1 Hz) sinusoidal inputs to reveal only its kinematical displacement characteristics. Hysteresis in the motion of the device was observed in the thrust direction and distinctive skew of the major axis of the elliptical trajectory of the cutting tool was also noticed. Discrepancy in the voltage-to-displacement characteristics of the piezoelectric actuators was found to largely contribute to the skew of the major axis of the elliptical trajectory of the cutting tool. Analytical kinematical model predicted the cutting direction displacement within 10 % error in magnitude with no phase error, but in estimating the thrust direction displacement, it showed a $27^{\circ}$ of phase-lag compared with the measured displacement with no magnitude error.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.88-93
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• 1997

Ball-end milling process is widely used in the die and mold manufacturing because of suitable for the machining of free-form surface. Pencil cutting can eliminate overload in uncut area caused by large diameter of ball-end mill before finish cutting. As the ball-end mill for pencil cutting is long and thin, it is easily deflected by cutting force. The tool deflection when pencil cutting is one of the main reason of the machining errors on a free-from surface. The purpose of the research is to find out the characteristics of deflected cutter trajectory by eddy-current sensor.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.9
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• pp.903-909
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• 2012

In elliptical vibration cutting(EVC) where the cutting tool traces a micro-scale 2-dimensional elliptical trajectory, the kinematical and vibrational characteristics of the EVC device greatly affect cutting performance. In this study, kinematical and vibrational characteristics of an EVC device constructed with two orthogonally-arranged stacked piezoelectric actuators were investigated both analytically and experimentally. The step voltage was applied to the orthogonal EVC device and the associated displacements of the cutting tool were measured to assess kinematical characteristics of the orthogonal EVC device. To investigate the vibrational characteristic of the orthogonal EVC, sinusoidal voltage was applied to the EVC device and the resulting displacements were measured. It was found from experiments that coupling of displacements in the thrust and cutting directions and the tilt of the major axis of the elliptical trajectory exists. In addition, as the excitation frequency is in vicinity of resonant frequencies the distortion in the shape of the elliptical trajectory becomes greater and change in the rotation direction occurs. To correct the shape distortion of the elliptical trajectory, the shape correcting procedure developed for the parallel EVC device was applied for the orthogonal EVC device and it was shown that the shape correcting method successfully corrects distortion.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.11
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• pp.52-58
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• 2007

A cutting device capable of generating various shapes of the cyclic elliptical trajectory of a cutting tool was proposed and micro v-grooving experiments were performed to investigate the characteristics of elliptical vibration cutting (EVC). The proposed cutting device is comprised of a pair of parallel piezoelectric actuators with which harmonic voltages of varying phase difference and magnitude are supplied, creating various shapes of the elliptical tool path. The attributes of the elliptical locus involving the direction of the axis of an ellipse, the rotational direction and amplitudes of a trajectory were fine-tuned for stable operation of the EVC. The EVC characteristics performed with brass and copper revealed reduction in the cutting resistance and suppression of burr formation, resulting in the enhancement of form accuracy of machined micro-features. While the effect of the EVC increases with the increase of excitation frequency and the amplitude, it is found that a change in the cutting force decreases as the amplitude of an elliptical locus increases.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.7
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• pp.789-795
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• 2011

In elliptical vibration cutting (EVC), cutting performance is largely affected by the shape of an elliptical path of the cutting tool. In this study, two parallel piezoelectric actuators were used to make an elliptical vibration cutting device. When harmonic voltages of $90^{\circ}$ out-of-phase are supplied to the EVC device, creation of an ideal elliptical trajectory whose major and minor axes are parallel to the cutting and thrust directions is anticipated from a kinematic analysis of the EVC device, however, the paths we experimentally observed showed significant distortions in its shape ranging from skew to excessive elongation of the major axis of the ellipse. To compensate distortions, an analytical model describing the elliptical path of the cutting tool was developed and verified with experimental results, and based on the analytical model, the distorted elliptical paths created at 100 Hz, 1 kHz, and 16 kHz were corrected for skew and elongation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.62-67
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• 2012

To realize 2-dimensional vibrational micro cutting in milling and drilling, etc. where the tools rotate, it could be a promising way to vibrate a workpiece instead of a rotating tool itself. In this study, an excitation work-table was developed using two piezoelectric materials orthogonally arranged. The trochoidal trajectory of a cutting tool which is necessary for 2D vibrational cutting is enabled in the excitation condition of higher excitation frequency and larger amplitude of vibration and the cutting condition of smaller diameter of cutting tool and lower spindle speed. The various trochoidal trajectories of a cutting tool could be generated in the excitation work-table by adjusting the input voltages to two piezoelectric materials and the phase between the two voltages and the trajectories could be readily used for the 2D vibrational micro cutting.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.169-170
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• 2012

• Proceedings of the IEEK Conference
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• 2002.06c
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• pp.55-58
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• 2002

Rapid Prototyping(RP) systems, that fabricate objects with slicers, typically bear staircase artifacts when slices has a certain degree of thickness. A tangential cutting algorithm is developed in order to remove surface distortion as well as to generate smooth laser-cutting trajectory. For this, an energy function is defined with tangential line length and distance between tangential line and middle contour. Then, the energy is minimized to generate effective tangential line segments. The proposed algorithm is tested and verified on 3D object samples and the results show that the generated tangential lines effectively approximate layer surface and make laser trajectory smooth.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.123-129
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• 1999

Ball-end milling process is widely used in the die and mold manufacturing because of suitable one for the machining of free-form surface. During the process, the pencil cutting operation can be adopted before finish cut to eliminate overload in uncut area caused by large diameter of ball-end mill. The ball-end mill cutter for the pencil cutting is easily deflected by cutting force due to the long and thin shape, and the tool deflection in pencil cutting is one of the main reason of the machining errors in a free-form surface. The purpose of this study is to find the characteristics of deflected cutter trajectory by constructing measurement system with eddy-current sensor. It was found that the severe reduction of corner radius produced the overcut during the plane cutting. Up cutting method induced the overcut both plane and slope cutting, but down cutting one induced the undercut. From the experiments, down cutting with upward cutting path can generate the small undercut surface.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.137-144
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• 1998

In this paper we present our research dealing with the problem of tool deflection during the milling. We try to compensate the errors by considering a new tool trajectory. In order to determine the compensated tool trajectory, the problem is divided in three steps : cutting forces model, tool deflection model and trajectory compensation. Starting from experimental data, we determine a cutting forces model., which allows us to anticipate the tool deflection along one nominal path. In order to determine the compensated tool trajectory, we propose in this paper a method of path compensation, called “mirror method”. This method of tool path optimization allows to minimize errors due to tool deflection. Several examples are processed in simulations and validated experimentally.