• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.107-115
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• 2014

Highly functional mill turrets have been developed and continuously improved to shorten the manufacturing time and enable multiple uses. Among these, a mill turret with B-axis rotary table was developed. The B-axis rotary table should be evaluated for structural integrity. Moreover, its worm and worm gear for transmitting power should be able to endure fatigue damage. Therefore, this article presents a structural analysis of this type of B-axis rotary table and confirms its static stability by comparing the stress results to the allowable stress levels. Next, the dynamic stability of the rotary table was investigated via a mode analysis and a harmonic analysis in a range determined by the results of a modal analysis. Finally, a worm gear set, the main part that drives the rotary table, is analyzed for fatigue and to estimate its lifetime. The results of the fatigue analysis allowed a prediction of the life of the worm gear set. The analytical results show that the B-axis rotary table has good structural integrity.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.103-108
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• 2018

In interrupted cutting, the workpiece has a groove that impacts both the cutting tool and the workpiece. Therefore, cutting tool damage occurs rapidly. In this study, I performed interrupted cutting of carbon steel for machine structures (SM20C) using an uncoated carbide tool (SNMG120404, P20), and observed tool damage, cutting chip shape, and the workpiece surface. Results: Under the specific cutting conditions of feed rate = 0.066 mm/rev, cutting speed = 120 m/min, and depth of cut = 0.1 mm; and feed rate = 0.105 mm/rev, cutting speed = 120 m/min, and depth of cut = 0.2 mm, the observed tool damage was small. Similar chip shape was observed (Expt. No. 1, 3, 7). Workpiece damage was observed (Expt. No. 3, 5, 7, 9).

• Journal of the Korean Society for Precision Engineering
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• v.14 no.4
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• pp.30-37
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• 1997

This thesis is concerned with the study on the characteristics of the tool failure occuring at the beginning of cutting in finish machining of hardened steels such as carbon tool steel and alloy tool steel by a ceramic tool (Al$_{2}$O$_{3}$+TiC) with nose radius. In the machining of hardened carbon steel STC3, the wear mechanism on the flank face of the ceramic tool is abrasion wear. The mode of tool failure is developed into catastropic fracture with flaking. It is thought that the fracture caused by FeO and TiO$_{2}$ results from the oxidation of Fe in the workpice and TiC in the ceramic tool and the deposit of Fe formed on the surface of the ceramic tool. In the machining of hardened alloy steel STD11, the wear mechanism on the flank face of the ceramic tool is that abrasion and adhesion wear exist simultaneously. The mode of tool failure at the beginning of cutting features is DOC notch wear. It is thought that the DOC notch wear caused by FeO and TiO$_{2}$results from the oxidation of Fe and TiC in the workpiece and ceramic tool, respectively.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.2
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• pp.46-53
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• 2000

Hot forging of aluminum alloy has the bad machinability due to continuous chip formation caused from the ductility The bad machinability requires a labor and a high cost to produce final products after hot forging. In industrial field, T4 heat treatment is performed to improve the machinability, and the annealing and the cold sizing are followed. In this study, a series of heat treatments are introduced during hot forging operation without T4 heat treatment after forming so that it improves the machinability with reduction of the number of operations and machining cost. Instead of T4 heat treatment, water cooling and air cooling are tried and compared to find out an optimum cooling condition

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.15-21
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• 2019

The fourth industrial revolution is noted. It is a smarter factory. At present, research on CNC (Computerized Numeric Controller) is actively underway in the manufacturing field. Domestic CNC equipment, acoustic sensors, vibration sensors, etc. This study can improve efficiency through CNC. Collect various data such as X-axis, Y-axis, Z-axis force, moving speed. Data exploration of the characteristics of the collected data. You can use your data as Random Forest (RF), Extreme Gradient Boost (XGB), and Support Vector Machine (SVM). The result of this study is CNC equipment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.4
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• pp.503-509
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• 2013

Carbon fiber reinforced plastics (CFRPs), a composite material, are generally vulnerable to compressive load and impact damage in a direction perpendicular to the surface of the material. In particular, during the operation of an aircraft, impact damages caused by bird collisions or falling tools reduce the strength of the aircraft structure. In this study, after impact damages were applied to CFRP specimens with various impact energies and impactor diameters, the compressive residual strength of the impact-damaged specimen was evaluated by performing a compression test. Furthermore, a prediction model for the compressive residual strength is proposed according to the variation in the impact energy by comparing the test results.

• Proceedings of the KIEE Conference
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• 2008.04b
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• pp.22-24
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• 2008

다도체 송전선로에서 전선 간격 유지 및 진동을 완화시켜주는 역할을 하는 스페이서댐퍼가 손상 받게 되면 즉시 유지보수 및 교체 작업을 하여야 한다. 그러나 이러한 작업은 송전선로 위에서 이루어지므로 전선의 장력과 작업자의 하중으로 인해 유지보수 및 교체작업이 매우 어렵고, 작업시간이 많이 소요되며, 전선표면손상, 스페이서댐퍼의 위치 변동 및 무리한 작업으로 인한 작업안전성 저하 등의 문제점이 있다. 따라서, 상기한 문제점을 해소하고 작업 효율의 상승을 위하여 작업시 각 전선의 간격을 쉽게 벌리고 좁힐 수 있는 작업용 공구인 스페이서지그(Spacer Jig)와 이를 이용한 송전선로의 스페이서댐퍼 유지보수 및 교체공법을 개발하여 교체작업시간 단축 및 작업안전성을 향상시킨 우수한 기술을 개발하였다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2077-2078
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• 2008

다도체 송전선로에서 전선 간격 유지 및 진동을 완화시켜주는 역할을 하는 스페이서 댐퍼가 손상 받게 되면 즉시 유지보수 및 교체 작업을 하여야 한다. 그러나 이러한 작업은 송전선로 위에서 이루어지므로 전선의 장력과 작업자의 하중으로 인해 유지보수 및 교체작업이 매우 어렵고, 작업시간이 많이 소요되며, 전선표면 손상, 스페이서 댐퍼의 위치 변동 및 무리한 작업으로 인한 작업안전성 저하 등의 문제점이 있다. 따라서, 상기한 문제점을 해소하고 작업 효율의 상승을 위하여 작업시 각 전선의 간격을 쉽게 벌리고 좁힐 수 있는 작업용 공구인 스페이서지그(Spacer Jig)와 이를 이용한 송전선로의 스페이서 댐퍼 유지보수 및 교체공법을 개발하여 교체작업시간 단축 및 작업안전성을 향상시킨 우수한 기술을 개발하였다.

• Journal of the Korean Society for Precision Engineering
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• v.2 no.1
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• pp.62-71
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• 1985

This is a study on the monitoring technique in tool failure and tool life by AE method. The relation between amplitude level of AE signal and flank wear width was studied by experiments. The relation between amplitude level of AE signal and tool life was also studied. As the result, it was observed that amplitude level of AE signal was only affected by cutting velocity. Amplitude level of AE signal was directly proportional to flank wear width and the increasing rate was related to cutting velocity. So, the relation between amplitude level of AE signal and tool life was represented as follow: $CT^n$ = $AE_{rms}$ where, n=0.35 C=9.5*$10^{-2}$

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.04a
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• pp.41-46
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• 1997

TiN 코팅은 마모에 대한 저항성 및 고체 윤활 효과가 매우 우수하여 내마모성 및 저마찰이 요구되는 절삭공구나 피스톤 베어링 및 각종 축계의 코팅막으로 사용이 증가되고 있다. 일반적으로 재료의 경도와 인성은 서로 상반 관계를 갖고 있어 공학적으로 경도와 인성을 모두 요구하는 표면을 얻기 위해 연질 모재 위의 세라믹 코팅은 그 요구를 만족시킬 수 있는 가장 각광받는 표면처리 방법중의 하나이다. 그러나, TiN과 같은 경질 박막의 공학적 적용시 가장 요구되는 마모수명은 모재의 조도나 경도, 증착 방법, 접촉 상태, 코팅막의 두께 및 마모의 발생 기구 등에 따라 마찰 및 마모 메커니즘의 현저한 차이를 나타내기 때문에 예측이 거의 불가능한 실정이고, 아직까지 이러한 마모수명 비교 평가방법에 대한 기준 설정 및 정량적 정립이 이루어지지 않고 있다. 본 연구에서는 모재의 경도, 조도, 코팅 두께가 다른 TiN 경질 박막에 압입시험과 스크래치시험시 발생되는 균열 발생 메커니즘과 미끄럼 시험시 발생되는 마모 메커니즘의 연계성을 밝히고 압입 및 스크래치 시험시 코팅막이 손상되는 임계하중과 미끄럼 시험시 접촉하중 변화에 따른 마모수명의 정량적 연관성을 찾아보고자 한다.