• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.605-609
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• 1996

Continuous sliding mode control is applied to turning process for cutting force regulation. The highest feedrate compatible with the allowable cutting force is applied in rough cutting process such that maximum productivity is ensured and tool breakage is avoided. The programmed feedrate is overridden after the control algorithm is carried out. However, most CNC lathe manufacturers offer limited number of data bits far feedrate override, thus resulting in nonlinear behavior of the machine tools. Such nonlinearity brings “quantized” effect, and the optimal faedrate is rounded off before being fed into the CNC system. To compensate for this problem, continuous sliding mode control is applied. Conventional switching control law at a sliding surface is replaced by a smooth control interpolation in a selected boundary layer to avoid the excitation of high-frequency dynamics. Simulation results are presented in comparison with those obtained by applying adaptive control.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.61-69
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• 2005

This paper presents the experimental results to analyze the atomization characteristics and environmental impact of cutting fluid in grinding process. Grinding is a major machining process to improve surface quality with different machining mechanism which is compared with turning or milling process. The environmental impact due to aerosol generation via grinding process is a major concern associated with environmental consciousness. Experimental results show that the generated fine aerosol which particle size less than 10 micron appears near working zone under given operational conditions. The aerosol concentration is much higher enough to affect human health risk with its generated aerosol quantities. This study can be provided a basic knowledge fur further research of environmental consciousness machining development.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1993.10a
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• pp.27-33
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• 1993

천마 연소관 및 Bracket는 고강도 특수강의 일종인 Maraging steel C-250 Grade로서 유동성형공정 (flow forming process: F/F) 및 용접공정을 거쳐 시효경화후의 경도(HRC 48-52)가 높아 절삭가공 및 Tapping에 어려움이 있다고 판단되어 브라켓 밀링가공(Tapping포함)을 시효경화공정 이전에 완성하는 것으로 공정 FLOW를 설정하였으나, 시효경화 시 유동성형공정 잔류응력 및 재질특성에 의한 수축, 변형 등으로 도면상 요구된 품질(형상 및 위치공차) 만족이 미흡하였을 뿐만 아니라 오히려 전체 공정 수만 증가하였음. 따라서 연소관 및 Bracket 완성가공을 시효경화 후에 실시하는 것으로 공정 개선 하고자 시험 작업한 결과, 선삭, 밀링작업등 다른 기계가공 공정의 문제점은 대부분 해결할 수 있었으나, Tapping공정만은 해결할 수 없어서 진정한 공정개선을 기할 수 없었음. 그러나, 제품의 품질 및 생산성을 고려 시효경화 후 Tapping 공정실시 필요성이 강력히 대두되어 Maraging steel 재질특성에 적합한 공구 및 작업조건을 검토, 설정 시험작업 함으로써 공정개선을 이룰 수 있었음.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.3
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• pp.1-7
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• 2016

The cutting processes used for monitoring engineering includes analysis and feedback about strange conditions, tools collision and tools wear in real time, for improving the working ratio of equipment and productivity. In this study, we proposed monitoring using profibus to increase the reliability as the most important factor for cutting monitoring. The profibus can increase the reliability of cutting monitoring for cutting torque of a main spindle motor and a feed motors through PLC-based interface.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.613-616
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• 1993

현재 가공시스템은 생산성 향상을 위해 다방면에 걸쳐 자동화가 시도되고 있고, 한 걸음 더 나아가서 무인화가 추구되고 있다. 이런 상황에서 자동화와 무인화의 효과를 극대화하기 위해 가공공정의 고속화, 즉 주축시스템과 이송시스템의 고속화서 활발히 진행되고 있다. 고속가공의 특징으로는 비절삭 시간의 절약과 절삭시간의 단축을 들 수 있는데 , 구조적으로도 큰 영향을 미쳐서 작은 절삭력의 발생으로 인해 구조물이 고강성화에서 저강성화로 변화되고 있다. 본 연구에서는 고속주축 Housing의 열전달 경로를 관찰하고 열변 위의 양상을 파악해서 전. 후부 베어링의 열발생량 차이에서 오는 주축심의 각변위 억제대책을 제시하고, 주축 Housing의 조립용 기준 핀을 Housing의 Z축방향 열변위가 최소가 되도록 위치를 결정하였다.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.4
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• pp.329-337
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• 2015

In this paper, a simulation based estimation method of energy consumption of the spindle and feed drives for the NC machine tool during the cutting process is proposed. To predict energy consumption of the feed drive system, position, velocity, acceleration and jerk of the table are analyzed based on NC data and then the power and energy are calculated considering friction force and mass of the stages. Energy consumption of the spindle is estimated based on models from acceleration motion of rotating parts, friction torque and power loss of motors. Moreover, simulation models of cutting power and energy for the material removal along the NC tool paths are proposed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.237-240
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• 2004

Indexable end mills, which consist of inserts and cutter body, have been widely used in roughing of parts in the mold industry. The geometry and distribution of inserts on cutter body are determined by application. This paper proposes analytical cutting force model for indexable flat end-milling process. Developed cutting force model uses the cutting-condition-independent cutting force coefficients and considers runout, cutter deflection and size effect for the accurate cutting force prediction. Unlike solid type endmill, the tool geometry of indexable endmill is variable according to the axial position due to the geometry and distribution of inserts on the cutter body. Thus, adaptive algorithm that calculates tool geometry data at arbitrary axial position was developed. Then number of flute, angular position of flute, and uncutchip thickness are calculated. Finally, presented model was validated through some experiments with aluminum workpiece.

• 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 Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1000-1003
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• 2001

This paper presents the numerical analysis and experimental verification to know the metal cutting burr formation mechanism in face milling operation. Finite element method are applied to predict the 2-D burr formation process prediction. Face milling process are adjusted to analyze the characteristics of burr shapes according to various cutting conditions. The cutting parameters were investigated with cutting speed, feed rate, depth of cut. Through the experiments various burr types are classified according to its shape and properties.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.11
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• pp.63-73
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• 1995

A mechanistic force system model considering the flank wear for the face milling process has been developed. The model predicts variation of the cutting forces according to flank wear in face milling over a range of cutting conditions, cutter geometries and cutting process geometries including relative positions of cutter to workpiece and rounouts. Flycutting and multitoth cutting teste were conducted on SS41 mild steel with sintered carbide tool. In order to verify the mechanistic force model considering the flank wear of cutting tools, a series of experiments was performed with single and multitooth cutters in various cutting conditions. The results show good agreement between the predicted and measured cutting force profiles and magnitudes in time and frequency domains.