Tribology and Lubricants

Korean Tribology Society (한국트라이볼로지학회)
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A Study on the Change in the Film Thickness of Ball Bearing in Starved EHL

윤활유 부족 상태에서의 볼 베어링 유막 두께 변화에 대한 연구

  • Jung, SoonBi (Dept. of Mechanical Engineering, Pusan National University) ;
  • Lee, Bora (Dept. of Mechanical Engineering, Pusan National University) ;
  • Yu, YongHun (Dept. of Mechanical Engineering, Pusan National University) ;
  • Cho, YongJoo (Dept. of Mechanical Engineering, Pusan National University)
  • Received : 2017.04.30
  • Accepted : 2017.05.20
  • Published : 2017.06.30
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Abstract

In this study, we perform a numerical analysis to predict the film thickness and lubrication regions for a thrust ball bearing under different operating conditions. Film thinning and replenishment affect the film thickness in starved lubrication. As the inlet meniscus position is brought to the edge of the Hertz contact, the thin film thickness is calculated as starved equation. We use a film replenishment model to determine the recovery film thickness between rolling elements. We use a hydrodynamic model to describe film recovery, that results from the effects of surface tension. In this model, we consider the surface tension gradient in fluid depression as the driving force for fluid recovery. We use Fourier transform method to determine the time-dependent depth of depressed oil. We calculate the change in the central film thickness graphically by using the recovery equation in starved elastohydrodynamic lubrication(EHL) under operating conditions that include numbers of balls, sliding velocity, applied force, and ambient film thickness. We evaluate the degree of starvation by using the distance from the center of the contact area to the meniscus position. Parched lubrication, a phenomenon where the film thickness decreases consistently, occurs at the severe condition. We determine optimal values with respect to the numbers of balls, and sliding velocity. The investigation can contribute to the design operating conditions for proper lubrication.

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References

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