• Tribology and Lubricants
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• 제20권6호
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• pp.314-321
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• 2004

Thermal distortion of non-contacting mechanical seals with inclined rubbing surfaces is affected by friction heat between seal ring and seal seat. The circulation fluid along the inclined rubbing surfaces maintains cooling friction heat and lubrication between the sealing surfaces of mechanical seal with an inclined surface. Mechanical seals with inclined sealing surfaces may be useful for reducing the frictional heating and power loss because of the introduction of cooling fluids to the sealing gap between seal ring and seal seat. From the FEM computed result shows that the thermal behavior and von Mises stress of sealing faces with an inclined angle 60 are much reduced in comparison of the conventional mechanical face seal with rectangular sealing surfaces.

• Tribology and Lubricants
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• 제11권5호
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• pp.172-176
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• 1995

This study deals with thermomechanical cracking between the friction surface and the interior of the brake disc. Analytical model considered in this study was a semi-infinite solid subjected to the thermal loading of an asperity moving with a high speed. The temperature field and the thermal stress state were obtained and discussed on the basis of Von Mises and Tresca Yielding Criterion. Analytical results showed that the dominant stress in cracking of friction brake is thermal stress and cracking location is dependent on the friction coefficient of contact and Peclet number. On the basis of analytical results thermomechanical cracking model is proposed.

• Elastomers and Composites
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• 제51권1호
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• pp.43-48
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• 2016

Multi-Surface (MS) treatment is a new technique of surface treatment to reduce the static friction factor on the surface of rubber. MS treatments include 4 methods which names are MS-V (UV-irradiation on the rubber surface), MS-M (doing the chemical reaction with double bond of rubber), MS-Q (dilution of rubber surface by silicone surfactant), and MS-P (coating and heating of rubber surface). The experiment and test of every MS-treatment had been carried out using acrylonitrile-butadiene rubber (NBR), ethylene-propylene-diene rubber (EPDM), and chlorosulphonated rubber (CSM) as rubber materials. It had introduced the steps of every MS-treatment process and the result of the properties test. From the research, it was found that the best method was MS-V treatment because it suited all the samples and the effect was obviously.

• 한국기계가공학회지
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• 제2권3호
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• pp.84-89
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• 2003

The joint method and characteristics of lubricant Impregnated MC nylon and metal are analyzed. Considering the productivity and economics, two materials are Joined with the process of turning, knurling, and induction heating. The Joint strength is determined by adhesion of the melted nylon, the size of knurl, and the interference from the difference of the diameters. The parameters affecting induction heating process are analyzed. The adhesion strength of the melted nylon is measured. Finally the joint strength is analyzed in the environments of low, room, and high temperature. The nylon/metal Joined material is expected to be widely used as the sliding machine elements with good friction and shear strength.

• 한국생산제조학회지
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• 제20권6호
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• pp.761-766
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• 2011

In this study, the optimized design profiles between a seal ring and a seal seat of contacting seal units has been proposed based on the FEM computed results. The maximum temperatures, the thermal distortions in axial and radial directions, and maximum contact normal stresses between a seal ring and a seal seat have been analyzed for various contact sealing profiles. The FEM computed results present that the contact area between seal rings and seal seats is very important for a good tribological performance such as low friction heating, low wear, high contact normal stress in a primary sealing components. The seal surface model III in which has a small sealing contact area shows low dilatation of primary sealing components, and high contact stress between a seal ring and a seal seat. This model with small contact surface of a seal ring produces high friction heating and contact stress. But the model III produces very small deformations of contacting sealing surface because of high convection heat transfer by cooling water circulation around the seal ring surface. Thus, the analysis results recommend a short width of a primary sealing unit rather than a big width of contact surfaces of contacting seal units for reducing a leakage and axial deformation of primary seal components.

• 드라이브 ㆍ 컨트롤
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• 제11권1호
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• pp.8-13
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• 2014

Hydraulic servo valves are widely used in various fluid power systems because of their fast response and precision control. In this paper, we studied the effect of metering notch shapes and amount of their openings on the flow characteristics within the spool valve using a computational fluid dynamic (CFD) code, FLUENT. To obtain the results for more realistic operating conditions, viscous heating due to the jet flow and viscosity variation of the hydraulic fluid with temperature were considered. For two types of notch shape, streamlines, oil temperature and viscosity distributions, and variations of flow and friction forces acting on spool were showed. The flow and friction forces affected by the metering notch shapes and their openings, and oil temperature rise near metering notch was significant enough to results in the jamming phenomenon. A thermohydrodynamic (THD) flow analysis adopted in this paper can be used in optimum design of hydraulic servo valves.

• Design & Manufacturing
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• 제15권3호
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• pp.7-12
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• 2021

Plastic injection molds used for rapid heating and cooling must minimize surface damage due to friction and maintain excellent thermal and low electrical conductivity. Accordingly, various surface treatments are being applied. The properties of Al₂O₃ coating and DLC coating were compared to find the optimal surface treatment method. Al₂O₃ coating was deposited by thermal spray method. DLC films were deposited by sputtering process in room temperature and high temperature PECVD (Plasma enhanced chemical vapor deposition) process in 723 K temperature. For the evaluation of physical properties, the electrical and thermal conductivity including surface hardness, adhesion and wear resistance were analyzed. The electrical resistance of the all coated samples was showed insulation properties of 24 MΩ/sq or more. Especially, the friction coefficient of high temp. DLC coating was the lowest at 0.134.

• 대한화장품학회지
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• 제50권1호
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• pp.11-18
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• 2024

최근에 모발 케어 화장품 효능으로서 모발 보습 효과를 소구하려는 시도가 있지만 아직까지 모발 수분 추출을 어떤 온도에서 진행해야 하는지 평가법이 정해져 있지 않아 공인된 인체시험 평가가 없는 실정이다. 모발 수분 정량평가법을 확립하기 위해서 본 연구는 진행되었다. 모발 수분의 거동 패턴을 확인하기 위해 할로겐 수분 분석기로 온도를 다르게 하여 모발에 열을 가할 경우 수분 검출량은 가열 온도가 증가하면 계속 늘어나는 것을 확인하였다. 시차주사열량계로 모발의 흡열 반응 에너지를 평가한 결과 75 ℃ 부근에서 급격한 흡열 반응이 일어나는 특이한 현상을 관찰하였다. 인종별로 다른 모발에서도 이 현상은 관찰되었다. 모발 큐티클 장벽을 산화, 열로 손상시킨 모발에서는 급격히 상승하는 이 흡열 반응 온도가 조금 더 높은 77 ℃에서 일어났고, 이 모발을 극성오일 또는, 컨디셔닝 폴리머나 케라틴 단백질로 도포한 경우에는 73 ℃에서 관찰되었다. 이 반응이 모발 표면에서 어떤 영향을 미치는지 알아보기 위해서 원자현미경으로 마찰력을 관찰한 결과 75 ℃ 보다 높은 온도에서 가열할 때 큐티클 마찰력이 상승하고 그보다 높은 90 ℃에서는 변화가 없는 것을 관찰하였다. 마침내 75 ℃ 근처가 모발에 결합된 수분 분자의 탈착이 본격적으로 일어나는 임계온도임을 결론내렸다. 이를 통해 모발 수분을 검출해서 정량화하기 위한 조건으로 75 ℃가 가열온도로 최적합하고 이 때 검출된 수분량 10% 가량이 모발 케어 화장품 처리 전과 후를 비교할 수 있는 모발 수분 정량 기준값이 될 수 있음을 제시하였다.

• 대한기계학회논문집A
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• 제21권1호
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• pp.53-61
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• 1997

The performance characteristics of magnetic fluid seals are studied numerically as a function of working gap, pole width, angle of pole sharpening, and shaft speed. The temperature distribution of a magnetic fluid seal with multiple tooth is investigated as a function of the contact fraction of magnetic fluids at the periphery of pole tooth using a finite element method. The most significant design parameter of a magnetic fluid seal is the working gap between the pole pieces and the rotating shaft. The result shows that with increasing the working gap, the friction torque decreases radically. The practical working gap for the pole pieces with triangular tooth zone profile is 0.2-0.4mm. The FEM results indicate that the optimal filling of a magnetic fluid between the pole pieces and the shaft is very important due to the accumulations of nonuniform friction heating within the pole pieces, which may interfere the magnetic circuit flow.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.505-510
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• 2002

The Friction Stir Welding (FSW) is a new joining method that was developed at The Welding Institute (TWI) in England in 1991. It applied heating by the rotational friction and material plastic flow. It was developed as a new joining method to solve the problems of epochally in the welding of Al alloys. In the study, 6000series of Alloy composed of AI-Mg-Si, one of the Al alloys that are utilized for shipbuilding and construction, is selected as a specimen and the numerical is executed against the welded zone of FSW. The material used in this study had the unique properties of strength and anti-corrosion, but since the welded joint of this material is easily softened by the welding heat, FSW is executed and the numerical analysis is carried out around the joint. To examine the mechanical behaviors and properties, F.E.M analysis is executed and the developed thermal-elastic-plastic [mite analysis are used.