Experimental Study on the Influence of Thickener Type on the Reflux Characteristics of Grease under Starved Lubrication

Some machine elements such as gears, rolling bearings, cams and traction drives operate under starved lubrication conditions where the average lubricant film thickness is considerably less than under fully flooded conditions. These parts must operate correctly, often over prolonged periods with sufficient performance. One of the most important parameters determining the performance and life of machine parts is a lubrication film thickness, which is generated within elastohydrodynamic lubricated (EHL) non-conformal contacts. The film thickness in this regime is often time dependent and its value is governed by lubricant supply. If loss outstrips supply this leads to very thin films, which can no longer fulfill their role of separating the surfaces, and thus component failure can result. To achieve optimum bearing performance and component life, it is obviously desirable to be able to predict when starvation will occur. Today the film thickness and pressure in EHL can be predicted using numerical models also in the case of starvation. Although it is very essential to solve the starved EHL problems very little work aimed at comparing experiment and theory has been done. Especially in the case where the starved lubrication model requires as input the inlet layer thickness. This is crucial if the validity of numerical models is to be properly established. This paper is focused on the study of starved lubrication conditions on lubrication film formation. A new optical test rig with multiple EHL contacts was developed for experimental study of lubrication film formation.

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Experimental Study of Stabilisation of Small Size Journal Bearing With Oil Supply Groove by Using Starved Lubrication and Bearing Orientation Angle Change

ASME/STLE 2007 International Joint Tribology Conference, Parts A and B ◽

10.1115/ijtc2007-44070 ◽

2007 ◽

Cited By ~ 1

Author(s):

Masayuki Ochiai ◽

Hiromu Hashimoto

Keyword(s):

Experimental Study ◽

High Speed ◽

Journal Bearing ◽

Orientation Angle ◽

Journal Bearings ◽

Rotating Machinery ◽

Angle Change ◽

Tilting Pad ◽

Starved Lubrication ◽

Rotating Machineries

Journal bearings are widely used for supporting high speed rotating machinery such as turbine, compressor and HDD spindle etc, because of their high load carrying capacity, stability and durability. Recently, the engineering trend is oriented to higher speed and smaller sizes of rotating machinery, and then it is important to enhance stabilities for the journal bearings. Tilting pad journal bearing is generally used for high-speed rotating machineries because of their advantages of stabilization. However, there are some problems using for compact size rotating machineries for their high manufacturing cost and complicated structure. Therefore, it is necessary to enhance the stability of more simple bearings compared with tilting pad bearing in order to use for small size rotating machinery. This paper describes the stabilization method of journal bearing based on the combination mechanism with starved lubrication and orientation angle change. From the results of stability experimental study of journal bearings, it is clarified that the stabilization of bearings is improved drastically by using above techniques.

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Experimental study on the restoration from a tilt-azimuth series for improvement in resolution

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010013955x ◽

1995 ◽

Vol 53 ◽

pp. 636-637

Author(s):

Norio Baba ◽

Norihiko Ichise ◽

Syunya Watanabe

Keyword(s):

Experimental Study ◽

Spherical Aberration ◽

Incident Beam ◽

Optical Parameters ◽

Beam Tilting ◽

Illumination Method ◽

Restoration Method ◽

Illumination Mode

The tilted beam illumination method is used to improve the resolution comparing with the axial illumination mode. Using this advantage, a restoration method of several tilted beam images covering the full azimuthal range was proposed by Saxton, and experimentally examined. To make this technique more reliable it seems that some practical problems still remain. In this report the restoration was attempted and the problems were considered. In our study, four problems were pointed out for the experiment of the restoration. (1) Accurate beam tilt adjustment to fit the incident beam to the coma-free axis for the symmetrical beam tilting over the full azimuthal range. (2) Accurate measurements of the optical parameters which are necessary to design the restoration filter. Even if the spherical aberration coefficient Cs is known with accuracy and the axial astigmatism is sufficiently compensated, at least the defocus value must be measured. (3) Accurate alignment of the tilt-azimuth series images.

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