• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.410-413
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• 2005

There are technical requirements to manufacture large size functional parts with not only simple geometries like a flat or spherical surface but also sculptured geometries. In addition, the required machining accuracy for these parts is becoming more severe day-by-day. In general, the forms of machined parts are determined by relative position between the workpiece and the tool during cutting. To improve machining accuracy, the relative position error should be maintained within the required accuracy. This study deals with estimation and calibration of depth of cut using AE signal in micro-machining.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.4
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• pp.38-45
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• 1997

A new dynamic model for the cutting process inb the end milling process is developed. This model, which describes the dynamic response of the end mill, the chip load geometry including tool runout, the dependence of the cutting forces on the chip load, is used to predict the dynamic cutting force during the end milling process. In order to predict accurately cutting forces and tool vibration, the model which uses instantaneous specific cutting force, inclueds both regenerative effect and penetration effect, The model is verified through comparisons of model predicted cutting force with measured cutting force obtained from machining experiments.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.48-68
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• 2000

The high-speed machining technology of difficult-to-cut material is needed to achieve the high-efficiency of die manufacturing. The high-speed machining is applied in automobile, airplane and electricityㆍelectro industry etc, because it can improve machining efficiency and productivity with high speed, high power and high rotation. In this study, high speed machinability, tool wear characteristics and its monitoring, characteristics of damaged layer, machinability of difficult-to-cut material, characteristics of a free curved surface and method of CAD/CAM system were introduced to acquire the shortening of machining time, the improvement of machining efficiency and the high quality of machined surface. Therefore, we establish the stabilization condition of difficult-to-cut material machining and present the optimal cutting condition for high-efficiency cutting.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.10a
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• pp.31-35
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• 2001

Three dimensional dynamic cutting can be postulated as an equivalent orthogonal dynamic cutting through the plane containing both the cutting vector and the chip flow velocity vector in cutting process. An analytical expression of dynamic cutting force is obtained from the cutting parameters determined by the static three dimensional cutting experiments. Particular attention is paid to the energy supplied to the vibration of the tool behind the vertical vibration and the direction. The phase lag of the horizontal vibration of the tool behind the vertical vibration and the direction angel of the fluctuating cutting force must be regarded in point of stability limits. Chatter vibration can effectively be suppressed by enlarging the dynamic rigidity of the cutting system in the vertical cutting force direction. A good agreement is found between the stability limits predicted by theory and the critical width of cut determined by experiments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.778-781
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• 2004

As the technique of high-speed end-milling is widely adopted to in machining field. The investigation for microscopic precision of workpiece is necessary for machinability evolution. In this study, cutting force, cutting temperature and microhardness were investigated to evaluate damaged layer in conventional machining and high-speed machining. Damaged layer was measured using optical microscope. The thickness of damaged layer depends on cutting process parameters, specially feed per tooth and radial depth. It is obtained that the characteristics of damaged layer is high-speed machining better than conventional machining.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.921-924
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• 2004

This paper is to investigate a crack for plasma sprayed MCrAlY coated material by acoustic emission method in 4-point bending test. The CoNiCrAlY is coated on Inconel-718 by vacuum plasma spray process. Micro-hardness measurement was conducted by means of Micro Vickers-hardness indentor. The porosity of coating layer was measured using a SEM and Image Analyzer. AE monitoring system is composed of PICO type sensor, a wide band preamplifier(40dB), a PC and AE DSP(16/32 PAC) board. The AE count, Hit and energy of coating specimens is measured according to coating thickness.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.3
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• pp.28-35
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• 2013

Micro electrical discharge machining (EDM) as a non-contact machining process is very effective for micromachining with a thin electrode because of its low machining reaction force. The micro-electrode machining device has the advantage of maintaining high precision through the whole processes and uses a feeding wire in the thin electrode tool manufacturing process. This study describes the design and evaluation of a micro-electrode machining device using optical photo-interrupter. The electrode was fabricated by reverse electrical discharge machining. The performance of designed system was evaluated to measure tension force according to feed speed of wire. This system for micro electrode fabrication proves the feasibility in the micro-EDM process of the micro holes and parts for industrial applications.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.3
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• pp.141-147
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• 2018

Recently, interest in customers has shifted to the emotional quality of customers as the driving, handling, and collision stability of automobiles have been greatly improved. The NVH performance of a vehicle is quantified and evaluated from the DPDS. To improve the DPDS, we need to optimize the shape without considering the increases in thickness of the parts or additions to the parts. And at the same time, we need to establish design and analysis processes to satisfy the requirements of the DPDS.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.4
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• pp.95-99
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• 2004

In this study, the leak detection technique of pressure vessel by using acoustic emission(AE) signal is suggested experimentally. The leak of pressure vessel is located at the welding line due to welding defects. we measured the AE signal using Rl5I sensor, and examined the AE parameters in leak condition. It is investigated that the mean value of AE signal is dependent on leak source location. So the absolute mean value of AE signal is adopted as dominant AE parameter. We proposed leak detection algorithm using AE signal mean value for monitoring the leak source location.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.155-159
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• 1993

최근 많은 생산 시스템의 자동화에 있어서 기계의 상태 진단 및 감시는 설비의 중요도 및 특수성를 고려할때 매우 중요한 비중을 차지하게 되며, 생산 작업을 최적화할 수 있는적당한 제어기술의 필요성과 그에 대한 관심이 날로 증가 하고있는 실정이다. 특히 가공분야에서 많은 부분을 차지하고 있는 절삭가공작업은 기구의 구성이 복잡하고 불확정한 요인을 포함하고있으며 공구의 파손이나 채터진동에 의한 공작물의 정도의 변화가 급속히 발생하기 때문에 이를 위하여 인프로세서 감시가 절실히 요구되고 있다. 그러므로 비정상적인 절삭을 사전에 감지하여 대처함으로써 최적의 작업조 건하에서 안정된 절삭을 할 수 있고 공작기계의 유지, 보수에 경제적인 절감을 기대할 수 있다. 본 연구에서는 2차원 절삭과정중에 발생하는 채터진도에 있어서 절삭 파라메타와 AE 신호와의 관계를 실험적으로 규명하며, AE를 이용한 절삭과정을 모니터링 할 수 있는 방법에 대하여 연구한다.