• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.72-77
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• 1999

This paper presents 2-dimensional vibration cutting increases dynamic stiffness of tool support and improves the quality of machined surface in micro-machining. 2-dimensional vibration cutting is generated by two piezo actuators arranged orthogonally. A sine-type voltage is input to one actuator and a phase-shifted sine-type voltage is input the other. Then the vibration device actuates the tool in a 2-D elliptical motion with pulsed cutting force. It is a characteristic of 2-D vibration cutting that some negative thrust force occurs as the direction of friction on a tool rake surface is reversed. It helps not only chip flow smoothly and continuously but also cutting force be reduced. The quality of machined surface by 2-D vibration cutting depends on such parameters as vibration amplitude, frequency, cutting speed, depth of cut, etc. Compared to conventional cutting through tool path simulation and experiments under several conditions, the 2-D vibration cutting is verified to bring forth a great decrease of cutting forces, much better surface roughness and moreover much less burr.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.3
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• pp.41-46
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• 2001

This paper discusses the feasibility of improving micro-machining accuracy by using two-dimensional(2-D) vibration cutting. Vibration cutting is generated by two piezo actuators arranged orthogonally : one is actuated by a sine curve voltage input, and the other is actuated by a phase-shifted sine curve voltage. A tool attached to the vibrator oscillates in a 2-D elliptical motion, depending on the frequencies, amplitudes, and the phase shifts of two input signals and the workpiece feedrate. Along the elliptical tool locus, cutting is done in the lower part, and non-cutting is done in the upper part. By this way a unique feature of 2-D vibration cutting, that is, air lubrication between a tool and chips, is caused. Another unique feature of 2-D vibration cutting was experimentally verified, that is, some negative thrust force occurs as the direction of chip movement on a tool rake face is reversed. Those features not only help chips flow smoothly and continuously but also reduce cutting force, which results in a higher quality machined surface. Through tool path simulations and experiments under several micro-machining conditions, the 2-D vibration cutting, compared to conventional cutting, was found to result in a great decrease in the cutting force, a much smoother surface, and much less burr.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.66-70
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• 2010

Using two piezoelectric materials orthogonally arranged, 2-dimensional(2D) vibration in a excitation workpiece table was generated. In this study, micro milling using high frequency 2D vibration was proposed, whose locus of cutting tool is combined with original trochoid locus of milling tool and 2D elliptical locus of excitation table. From the cutting results of 2D vibrational micro milling of nickel alloy, it was observed that the machining quality and the roughness of machined surface were enhanced compared to conventional milling in a side cutting whose immersion ration is relatively low, whereas there was little betterment in a slot cutting.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.4
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• pp.419-424
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• 2004

In order to increase the efficiency of the sawdust machine, the helical type drums with an oblique cutting condition (3D) were developed. The preexisting drums have an orthogonal cutting condition (2D) considering of a saw cutter and a wood cutting pattern. Unfortunately, the disadvantages of this type drum are the big cutting resistance, the high cost of a cutting power and the extreme occurrence of a vibration. To improve this shortcoming, the helical type drum with an oblique cutting condition was developed. Therefore, this type drum decreased the vibration and the cutting resistance of the sawdust machine, and also improved the productivity of 30% or more and the porosity of the sawdust.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.2
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• pp.85-94
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• 1994

The cutting mechanism of ultrasonic vibration machining is characterized as two phases, that is, an impact at the cutting edge and a reduction of cutting force due to non-contact interval between tool and workpiece. In this paper, in order to identify cutting dynamics of a system with ultrasonically vibrated cutting tool, an ARMA modeling is performed on experimental cutting force signals which have a dominant effect on cutting dynamics. The aim of this study is, through Dynamic Date System methodology, to find the inherent characteristics of an ultrasonic vibration cutting process by considering natural frequency and damping coefficient. Surface roughness and stability of cutting process under ultrasonic vibration are also considered

• 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 Machine Tool Engineers Conference
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• 2004.04a
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• pp.88-92
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• 2004

We developed a helical type drum with an oblique cutting condition for sawdust machine. The existing drum has an orthogonal cutting(2D) condition considering of saw cutter and wood cutting pattern. Additional disadvantage of this type include big cutting resistance, high cost of cutting power and extreme occurrence of vibrations. To improve this shortcoming, we developed a helical type drum with an oblique cutting(3D) condition, therefore, this type drum decreased the vibration and cutting resistance of sawdust machine, and also improved productivity and sawdust porosity.

• Journal of Korean Society of Steel Construction
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• v.13 no.3
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• pp.301-311
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• 2001

For a rectangular-highrise building with aspect ratio about six, the resonant wind speed of wind-induced vibration or galloping start wing speed can be within the design wind speed. The wind-induced vibration and galloping of highrise building with aspect ratio $H/\sqrt{DB}=6$, side ratio D/B=1 to 2 at intervals of 1/4 D/B were investigated in smooth flow. For the reducing effect of wind-induced vibration of highrise building, rectangular-highrise building with corners cutting about side ratio D/B=2 were investigated. Experimental results show that in the smooth flow non corners-cutting cases have tendency of increasing wind-induced vibration and galloping vibration then corner-cutting section. Therefore, the wind-induced vibrations on rectangular-highrise buildings were reduced effectively by using corner cut method.

• Journal of KSNVE
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• v.7 no.1
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• pp.107-116
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• 1997

Friction between stone and saw of stone cutting machine generates the noise of 96-104 dB in the frequency range of 2kHz-8kHz, which may cause occupational hearing loss. By designing enclosures which are made of transparent acryl, PVC panel and absorption materials, about 15 dB noise reduction has been achieved in the stone cutting factory. It is demonstrated that this kind of enclosures can be effectively used to reduce the noise in the stone cutting factory.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.3
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• pp.273-278
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• 2014

This study presents a chatter vibration avoidance program for the milling process. Chatter vibration has a negative effect on workpieces and spindle-tools. When chatter vibration occurs, the cutting tool is loaded dynamically, a chatter pattern is generated on the workpiece, and the tool life is reduced. The developed program is composed of various modules such as an FFT analyzer, an impact test analyzer, a chatter vibration indicator, and a spindle speed recommender. The proposed program is verified using an AISI D2 cutting experiment in milling process. The effect of chatter vibration on the machining condition can be simulated by the suggested method, and successfully exploited to avoid chatter vibration.