• 대한기계학회논문집A
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• 제37권4호
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• pp.437-442
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• 2013

마찰을 크게 줄임과 동시에 신뢰성을 향상시키기 위하여 평행 스러스트 베어링, 메카니컬 시일과 피스톤링 등과 같은 기계부품에 표면가공방법이 최근에 적용되고 있다. 본 논문에서는 상용 전산유체역학 S/W인 FLUENT를 사용하여 반구형 미세딤플이 등간격으로 배치되어 있는 슬라이더 베어링의 윤활특성을 조사하였다. 미세딤플의 직경과 수에 따라서 압력분포, 지지하중, 누설유량과 마찰력은 아주 크게 변화하였다. 특히, 딤플의 밀도증가에 따라서 지지하중과 마찰력은 거의 선형적으로 감소하는 반면에 누설유량은 급격하게 증가하였다. 본 논문의 결과는 각종 미끄럼 베어링의 윤활성능을 향상시키기 위한 최적 딤플설계에 사용할 수 있으며, 추가적인 연구가 요구된다.

• Tribology and Lubricants
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• 제36권4호
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• pp.193-198
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• 2020

Fluid film bearings are among the best devices used for overcoming friction and reducing wear. Surface texturing is a new surface treatment technique used for processing grooves and dimples on the lubricated surface, and it helps to minimize friction further and improve the wear resistance. In several studies, parallel surfaces, such as thrust bearings and mechanical face seals, have been investigated, but most sliding bearings have a convergent film shape. This paper presents the third part of a recent study and focuses on the effect of the groove shape on the lubrication performance of inclined slider bearings, following the two previous papers on the effects of the groove position and depth. We adopted the continuity and Navier - Stokes equations to conduct numerical analyses using FLUENT, which is a commercial computational fluid dynamics code. The groove shape adopted in the numerical analysis is rectangular and triangular, and its depth is varied. The results show that the streamlines, pressure distributions, and groove shape significantly influence the lubrication performance of the inclined slider bearing. For both shapes, the load-carrying capacity (LCC) is maximum near the groove depth, where vortices occur. In the shallow grooves, the LCC of the rectangular shape is higher, but in deeper grooves, that of the triangular shape is higher. The deeper the rectangular groove, the higher the decrease in the frictional force. The results of this study can be used as design data for various sliding bearings.

• Tribology and Lubricants
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• 제35권6호
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• pp.376-381
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• 2019

Surface texturing is widely applied to reduce friction and improve the reliability of machine elements. Despite extensive theoretical studies to date, most research has been limited to parallel thrust bearings, mechanical face seals, piston rings, etc. However, most sliding bearings have a convergent film shape in the sliding direction and the hydrodynamic pressure is mainly generated by the wedge action. The results of surface texturing on inclined slider bearings are largely insufficient. This paper is the first part of a recent study focusing on the effect of the groove position on the lubrication performances of inclined slider bearings. We model a slider bearing with one rectangular groove on a fixed pad and analyze the continuity and Navier-Stokes equations using a commercial computational fluid dynamics (CFD) code, FLUENT. The results show that the film convergence ratio and the groove position have a significant influence on the pressure and velocity distributions. There are groove positions to maximize the supporting load with the film convergence ratio and the groove reduces the frictional force acting on the slider. Therefore, the proper groove position not only improves the load-carrying capacity of the slider bearings but also reduces its frictional loss. The present results apply to various surface-textured sliding bearings and can lead to further studies.

• Tribology and Lubricants
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• 제35권6호
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• pp.382-388
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• 2019

It is currently well known that surface textures act as lubricant reservoirs, entrap wear debris, and hydrodynamic bearings, which can lead to certain increases in load-carrying capacities. Until recently, the vast majority of research has focused on parallel sliding machine components such as thrust bearings, mechanical face seals, piston rings, etc. However, most sliding bearings have a convergent film shape in the sliding direction and their hydrodynamic pressure is mainly generated by the wedge action. Following the first part of the present study that investigates the effect of groove position on the lubrication performances of inclined slider bearings, this paper focuses on the effects of groove depths and film thicknesses. Using a commercial computational fluid dynamics (CFD) code, FLUENT, the continuity and Navier-Stokes equations are numerically analyzed. The results show that the film thickness and groove depth have a significant influence on the pressure distribution. The maximum pressure occurs at the groove depth where the vortex is found and, as the depth increases, the pressure decreases. There is also a groove depth to maximize the supporting load with the film thickness. The friction force acting on the slider decreases with deeper grooves. Therefore, properly designed groove depths, depending on the operating conditions, can improve the load-carrying capacity of inclined slider bearings as compared to the bearings without a groove.