• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.124-129
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• 2017

In this study, we report characteristics of friction stir welding (FSW) technique applied to Al-6005-T6 extruded sheets, which is a common material for railway car bodies. With the welding speed fixed at 300 mm/min, the revolution per minute (RPM) of the rotating tool was varied from 600 to 1800 RPM, with the aim at evaluating the resultant microstructure and mechanical behaviors. Comparison is also made with the conventional Metal Inert Gas (MIG) welding technique. Unlike MIG, no micro-voids were observed for FSW specimens. Hardness measurement revealed that the increased heat input by increasing RPM results in widened heat affected zone (HAZ) and decreased hardness for HAZ due to grain coarsening. Hardness results for the nugget do no show difference. During tensile tests, specimens fractured at HAZ, and increasing rpm led to decrease of the yield stress and tensile stress for the selected RPM range, which is considered to be due to the grain coarsening for HAZ.

• Journal of Convergence for Information Technology
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• v.9 no.7
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• pp.94-99
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• 2019

Friction stir welding was first reported by TWI(The Welding Institute) in 1991, and this welding method has been rapidly used in various industrial areas such railway, automobile, aerospace and shipbuilding industry. Here, we study core characteristics of friction stir welding (FSW) applied to Al 6005-T6 extruded sheets, which is the typical alloy used for railway car bodies. With the fixed welding speed of 500 mm/min, the rotating tool speed was varied from 600 to 1800 RPM. The results of hardness measurement revealed that the hardness of nugget area is ~70% with respect to the parent material, and for the selected range of rotation speed, no clear dependence was observed and the hardness values close to the parent materials were achieved for the area located 5 mm away from the welding interface. The tension test shows that yield strength and tensile strength were slightly decreased with increasing RPM, with no observed difference for the elongation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.6
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• pp.591-598
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• 2012

In this study, the cutting characteristics of bulk metallic glass (BMG) cut using a computer numerically controlled (CNC) lathe were investigated for different insert tool materials and cutting speeds. The surface roughness, chip morphology, cutting forces, and tool wear during turning of $Zr_{50}Cu_{40}Al_{10}$ BMG alloy were examined. Four kinds of tool materials were used to cut an 8-mm-diameter BMG. The examination of the surface roughnesses of the BMG specimens machined at each cutting speed showed that the surface roughness became better as the cutting speed increased, and the tool materials also influenced the surface roughness. The chip morphology investigations showed that the unoxidized BMG chips had serrated curled chips with adiabatic shear bands, while the oxidized chips exhibited local melting and tangling rather than the usual spiral-shaped chips. The cutting force induced during machining of the Zr-based BMG was the largest for the TiN-WC tool, followed by the polycrystalline diamond (PCD) tool. The cermet tool exerted the smallest cutting force.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.497-500
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• 2000

절삭 작업과정에서 발생하는 버는 공구와 피삭재가 만나는 상태에 따라 그 형상이 결정되어진다. 공구와 피삭재 사이의 각, 공구의 회전속도, 이송속도, 피삭재의 종류등은 이러한 버의 형상을 결정하는데 결정적인 역할을 하므로, 실험에 의해서 생성된 단계별 자료를 CAD 및 CAM 데이터와 연관시켜 효율적인 알고리즘을 만들고자 한다. 특별히 공장자동화에 따른 작업의 자동화뿐 아니라 관리 체계의 정립을 위하여 전문가 시스템의 도입 역시 시급히 요구되고 있는 실정이다. 여기서 CAD 데이터는 피삭재에 대한 특징 형상의 정보를 포함하고 있기 때문에 피삭재의 형상에 대한 정보를 얻을 수 있다. 인식된 형상에 대하여 Exit 버 형성시 접점과 Exit Angle을 계산하기 위해 도형의 방향인식이 필요하며, 이를 통해 공구와 피삭재와의 관계를 산출하여 Exit 버의 판별을 수행할 수 있다. 본 논문에서는 이러한 과정을 수행하는 프로그램을 개발한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.3
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• pp.181-186
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• 2017

Single point incremental forming (SPIF) is a sheet-forming technique. It is a die-less sheet metal manufacturing process for rapid prototyping and small batch production. The Critical parameters in the forming process include tool diameter, step depth, feed rate, spindle speed, etc. In this study, these parameters and the die shape corresponding to the Varying Wall Angle Conical Frustum(VWACF) model were used for forming 0.8mm in thick Al5052-O sheets. The Taguchi method of Experiments of Design (DOE) and Grey relational optimization were used to determine the optimum parameters in SPIF. A response study was performed on formability, spring back, and thickness reduction. The research shows that the optimum combination of these parameters that yield best performance of SPIF is as follows: tool diameter, 6mm; spin speed, 60rpm; step depth, 0.3mm; and feed rate, 500mm/min.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.560-567
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• 2020

Incremental Sheet Forming (ISF) is a unique sheet-forming technique. The process is a die-less sheet metal manufacturing process for rapid prototyping and small batch production. In the forming process, the critical parameters affecting the formability of sheet materials are the tool diameter, step depth, feed rate, spindle speed, etc. This study examined the effects of these parameters on the formability in the forming of the varying wall angle conical frustum model for a pure Al3004 sheet with 1mm in thickness. Using Minitab software based on Back Propagation Neural Network (BPNN) and Genetic Algorithm (GA), a second order mathematical prediction model was established to predict and optimize the wall angle. The results showed that the maximum forming angle was 87.071° and the best combination of these parameters to give the best performance of the experiment is as follows: tool diameter of 6mm, spindle speed of 180rpm, step depth of 0.4mm, and feed rate of 772mm/min.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1572-1586
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• 1991

본 연구에서는 볼 엔드밀 공구를 사용한 코너가공에서 절삭력을 예측하고, 가 공중 공구의 회전주기에 대한 최대 수평합력(max. resulant force)을 일정하게 유지시 키는 모델을 개발하고, 코너가공에 적용한다. 또 금형가공에는 절삭시간을 많이 소 요하여 생산성이 떨어지게 하는 주요한 원인이 되기 때문에 최대 수평합력을 황삭가공 에 적합하도록 설정하면 본 연구의 결과로 이송속도를 결정할 수 있다.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.1
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• pp.73-79
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• 2013

In this study, NIMAX material has been processed using the three-dimensional measuring instrument and white light interferometer. they were tested to roundness and surface roughness and results are as follows: As for a cutting characteristic, it indicated that F4 showed a lower result than 2F showed due to the high hardness of the material and showed a good result when spindle rotation speed and tool feed were low. As for the measurement of roundness through 3-Dimensional measuring machine, it indicated that 4F showed a good result like the condition of cutting component and that roundness showed a good result when spindle rotation speed of 1,700 rpm and tool feed speed of 85 mm/min were applied. As for the surface roughness of processing surface, Surface roughness showed better 4F than 2F and conditions of spindle rotation speed 1,700 rpm, tool feed rate 55 mm/min showed good results in the Ra $0.4025{\mu}m$.

• 기계와재료
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• v.24 no.2
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• pp.96-109
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• 2012

채터진동은 공작기계에서 가공중에 소재와 공구사이에 나타나는 급격한 상대진동을 말한다. 이러한 진동은 가공 소재 품질에 심각한 영향을 미치는 요소일 뿐만 아니라 가공툴과 기계에 손상을 유발시키는 인자이기도 하다. 본 연구는 공작기계의 구동 중 발생되는 채터진동을 실시간으로 감지하여 공구의 회전속도와 이송 속도를 제어하여 자율보정함으로써 보다 빨리 채터진동의 영향을 보상함을 물론 보다 정밀한 가공물을 생산할 수 있는 채터진동 감지 및 보정에 관한 것이다. 실시간 처리를 위하여 본 연구에서의 공작기계의 채터진동 보상장치는 공작기계에 임베디드 형태의 디바이스로 개발되었으며, 구성은 공작기계의 채터진동을 감지하는 센서와 센서로부터 감지된 채터진동에 따라 보상값을 예측하여 산출하는 채터보상기를 포함하여 공작기계의 CNC제어기의 연계 구성됨을 특징으로 한다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.129-134
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• 2013

Titanium used in industry has been widely applied for aerospace important parts and automobile important parts, etc. because the titanium is higher in strength compared to the steel and light in weight compared to the steel. This study is to investigate the effect of cutting tool cooling method and cutting time on the spindle speed and feed rate of vertical machining center as a parameter to find the rough cutting time in the medium speed cutting machining of the titanium alloy. It is found that the cutting machining heat are increased as the feed rate, cutting time and spindle speed are raised.