• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.117-117
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• 2004

일반적으로 접촉 피로 마멸은 구름 또는 미끄럼 접촉시 작용하는 반복 응력에 의해 표면과 표면 아래에 균열이 형성되고 성장 및 합체의 과정을 거쳐 표면의 일부가 떨어져 나가는 손상으로 기어나 캠-롤러, 구름 베어링과 같이 구름-미끄럼 접촉상태로 운전하는 기계요소에서 가장 중요하게 고려되어야 할 파손 메커니즘이다. 특히 기어나 구름 베어링 같이 고주기 접촉 피로 특성을 지니는 기계요소의 수명은 피로수명 실험과 통계적 기법을 이용한 Weibull 이론을 기초로 한 수명식을 대부분 사용하고 있다.(중략)

• Tribology and Lubricants
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• v.15 no.4
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• pp.291-296
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• 1999

This paper presents the results of thermoelastic wear behaviors in ventilated disk brakes for a high-speed automotive and train using the finite element method. The computed results show that the sinusoidal distortions due to non-uniform distributions of temperature profiles may lead to thermoelastic wears on the rubbing surface. This may decrease the service life of a disk brake and produce micro-cracks, noise and squeals between two rubbing surfaces.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1990.06a
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• pp.45-52
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• 1990

고도의 신뢰도를 요구하는 정밀기계의 보편화는 트라이볼로지 요소중에서 밀봉기능에 관련된 시일의 해석 및 설계가 커다란 관심사로 부각되었다. 특히 고속회전을 요하는 경우에 대한 회전 시스템의 동적 안정성은 대단히 중요하다. 미끄럼 접촉운동을 하고 있는 기계평면시일의 시일링 간극은 대단히 작기 때문에 시일의 접촉면에서 형상이 변화하게 되면 시일 성능은 커다란 영향을 받게 된다. 시일의 접촉표면 가공시 발생되는 평면도(flatness), 조립시의 회전축과 시일축 사이의 중심 맞추기의 어려움, 회전축의 자중량 등 때문에 발생되는 회전링 사이의 상대적인 경사도(misalignment)는 시일의 동적 불안정성에 영향을 준다. 또한 상대 접촉 운동면에서 경계 또는 고체 마찰에 의한 마멸의 진행은 시일의 코닝(coning) 현상을 일으킨다. 본 연구에서는 비압축성 유체가 온도의 영향을 받아 점도가 선형적으로 변화하는 경우에 대한 시일링 간극 내에서의 압력분포를 유한차분법을 이용하여 해석하였다. 여기서 얻어진 결과를 이용하여 시일의 축력과 모우멘트를 해석함으로써 시일의 동적 불안정성에 대하여 논하였다. 이 때 기계평면 시일의 형상은 코닝이 있고, 시일의 중심축이 경사진 경우를 고려하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.193-193
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• 2004

자기 브레이크(Magnetic Brake)는 기계식 브레이크와 달리 비접촉식으로 제동이 가능하여, 마모 등에 따른 제동 효과의 저감이나 브레이크의 수명 단축을 배제할 수 있어 그 사용 범위가 확장되고 있는 추세이다. 특히 최근에는 영구자석의 발전에 힘입어, 강한 보자력을 갖고 있는 영구자석이 개발됨에 따라 코일 둥의 능동 요소 없이 반영구적으로 효과적인 제동을 발휘 할 수 있다［1］. 자기 브레이크는 고속 이송 또는 회전 시 기계식 브레이크에서 발생되는 점착(adhesion) 현상으로 인한 성능 한계를 극복하기 위하여 개발되어 왔으며, 최근에는 자기 부상 분야와 고속 주행 차량의 마멸에 의한 기계식 브레이크의 성능 감소를 피하기 위해 이용되고 있다.(중략)

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.74-80
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• 2016

Due to the increased use of power caused by industrial development, the importance of improving wear and friction in the contact region has emerged. Except for some parts, such as brakes or clutches and friction, seals and precision mechanical parts (e.g., pistons, bearings, valves, and cams) are important engine components that require low friction characteristics. In this study, the experimental method used to determine the friction characteristics was based on the type of rpm with the pin-on-disc test device, the element analysis program ANSYS was used to analyze the surfaces of the two metals rubbing together, and physical formation FEM models were used to study the properties and wear. The friction coefficient of variation was unsafe, but at the start of wear, it converged to a stable friction coefficient that increased after a certain slip away.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.193-199
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• 2002

Analyzing working conditions with shape characteristics of wear debris in a lubricated machine, it can be effect on diagnosis of hydraulic machining system. And it can be recognized that results are processed threshold images of wear debris. But, in order to predict and estimate a working condition of lubricated machine, it is need to analysis a shape characteristic of wear debris and to identify. Therefor, If shape characteristics of wear debris are identified by computer image analysis and the neural network, it is possible to find the cause and effect of wear condition. In this stud)r, wear debris in the lubricant oil are extracted by membrane filter $(0.45{\mu}m)$, and the quantitative value of shape characteristic of wear debris are calculated by the digital image processing. This morphological information are studied and identified by tile artificial neural network. The purpose of this study is to apply morphological characteristic of wear debris to prediction and estimation of working condition in hydraulic machining systems.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.575-578
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• 2000

Die design to minimize the die wear in the cold forging process is very important as it reduce the production cost and the increase of the production rate. The quantitative estimation for the die wear is too hard because the prediction of the die wear is determined with many process variables. So, in this paper, the optimal shape of the backward extrusion punch is newly designed through the FE-analysis considering the surface expansion and Archard's wear model in order to reduce the rapid wear rate that is generated for the backward extrusion product exceeding the forming limit. The main shape variables of the backward extrusion punch are the flat, angle, and round of the punch nose part. As the flat and angle of the punch nose are larger, the surface expansion is reduced. and, the wear rate is decreased according to the reduction of the punch round. These results obtained through this study are applied to the real manufacturing process, it is implemented the reduction of the wear rate.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.180-187
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• 2004

Die design to minimize the die wear in the cold forging process is very important as it reduce the production cost and the increase of the production rate. The quantitative estimation fur the die wear is too hard because the die wear is caused by many process variables. So, in this paper, the optimal shape of the backward extrusion punch is newly designed through the FE-analysis considering the surface expansion and Archard wear model in order to reduce the rapid wear rate that is generated for the backward extruded products exceeding the forming limit. The main shape variables of the backward extrusion punch are the flat diameter, angle, and round of the punch nose part. As the flat diameter and angle of the punch nose are larger, the surface expansion is reduced and the wear rate is decreased according to the reduction of the punch round. These results obtained through this study can be applied to the real manufacturing process.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.5
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• pp.30-37
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• 2002

Single flighted screw injection technology is the most cost effective method for the production of film, sheet, pipe and the fundamental step in other processes including blow molding and injection molding. The temperature of polymer melts and injection pressure play a very important role in the injection molding machine. Thermal distortion and displacement of a screw by temperature difference and injection pressure difference ratio cause a friction and thermoelastic wear by metal-to-metal contact between the screw and the cylinder. In this paper we analyzed thermal distortions of a screw as functions of temperature distribution and pressure profiles by finite element analysis.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.1
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• pp.79-87
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• 1999

The most part of the faculty drop a trouble and damage of machine equipment even if whatever cause they break out take place at local and trifling place and the factor dominating their trouble is due to wear debris occurred in the lubricated machine moving surface. This study has been car-ried out to identify morphology of wear debris on the lubricated machine moving system by means of computer image analysis. Namely the wear debris contained in lubricating oil extracted from movable machine equipment will be filtered through membrane filter(void diameter 0.45${\mu}m$) and will be analyzed with its data information such as 50% volume diameter aspect roundness and reflectivity. Morphological characteristic of wear debris is easily distinguished by four shape parameters it is necessary to divide small class of every 100 wear debris in total wear particles in order to distinguish morphological characteristic of wear debris more easily by computer image analysis. We are sure that operation condition diagnosis of the lubricated machine moving surfaces is possible by computer image analysis.