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Article
Publication date: 14 September 2015

Kai Zhang, Qingfeng Meng, Wei Chen, Junning Li and Phil Harper

This paper aims to measure the oil film thickness between the roller and the inner ring in roller bearings by the ultrasonic method. The oil film thickness between the…

Abstract

Purpose

This paper aims to measure the oil film thickness between the roller and the inner ring in roller bearings by the ultrasonic method. The oil film thickness between the roller and the inner ring in roller bearings is a key performance indicator of the bearing lubrication condition. As the oil film is very thin and the contact region is very narrow, measurement of this film thickness is very challenging. A promising ultrasonic method was used to measure this film thickness, and this method was expected to overcome some drawbacks in other methods.

Design/methodology/approach

A simplified roller bearing only configured one roller, and an inner ring was built up to investigate this measurement. A miniature piezoelectric element is bonded on the inner surface of the inner ring to measure the reflection coefficient from the layer of oil between the roller and the inner raceway. As the width of the line contact region is smaller than the width of the piezoelectric element, a ray model is used to calibrate the reflection coefficient measured. The quasi-static spring model is then used to calculate oil film thickness from the corrected reflection coefficient data.

Findings

The results measured by this method agree reasonably well with predictions from elastohydrodynamic lubrication (EHL) theory. Also, a dynamic displacement of the rig caused by the skid of the roller versus the inner ring was found under light-load and high-speed conditions.

Originality/value

This work shows that the oil film between the roller and the inner raceway in roller bearings can be measured accurately by ultrasound and shows a deal method when the contact width is smaller than the piezoelectric element width.

Details

Industrial Lubrication and Tribology, vol. 67 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 June 1988

Terence W. Bates, Brian Williamson, James A. Spearot and Chester K. Murphy

Oil film thickness measurements made in the front main bearing of an operating 3.8 L, V‐6 engine were compared with rheological measurements made on a series of commercial…

Abstract

Oil film thickness measurements made in the front main bearing of an operating 3.8 L, V‐6 engine were compared with rheological measurements made on a series of commercial and experimental oil blends. High‐temperature, high‐shear‐rate viscosity measurements correlated with the film thickness of all single‐grade and many multigrade oils. However, the film thickness provided by some multigrade oils were larger than could be accounted for by their high‐temperature, high‐shear‐rate viscosities alone. Although the pressure/viscosity coefficients of some of the oils were significantly different from those of the majority of oils tested, they were not oils which produced unusual film thicknesses. As a consequence, correcting oil viscosities for the esimated pressures acting within the bearing was unsuccessful in improving the correlations. The correlations were improved, however, by accounting for the elastic properties of the multigrade oils. Measurements of oil relaxation times at high temperatures and shear rates showed large differences in elastic properties among the test oils. A good correlation (R2 = 0.73) was obtained from a multiple linear regression of film thickness as a function of both high‐temperature, high‐shear‐rate viscosities and relaxation times.

Details

Industrial Lubrication and Tribology, vol. 40 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 March 1981

J.C. PEMBERTON and A. CAMERON

All measurements of EHD film thicknesses were carried out in simulated test machines. This study uses an actual bearing. A test rig which used a 65mm bore radial…

Abstract

All measurements of EHD film thicknesses were carried out in simulated test machines. This study uses an actual bearing. A test rig which used a 65mm bore radial cylindrical roller bearing was constructed with a specially designed sapphire window in the outer track. Full loads, and speeds to 3000 rpm were applied. With specially polished rollers and chromic oxide coating on the window excellent interferometric film thickness measurements were found possible. A Xenon flash lamp was used and a Xenon Iaserof0–50pps,pulse half width of 150ns and peak power of 100 watts was developed for this research. A microscope and 35mm camera as well as video tape were used for recording results. Arrangements were made to study any chosen roller and the side of the bearing was also open to view. First the film measurements, when corrected for inlet zone viscous heating, agreed admirably with theoretical predictions for mid and exit film thickness. The effect of inlet boundary length on the film was then investigated in some depth. Studying the effect of the multiple roller system, a number of techniques were used to demonstrate that the inlet boundary length, which controls the lubricant film thickness, was itself controlled by the film thickness between the rollers and track in the unloaded zone. The ribs of oil, formed at either edge of the roller, are only secondary sources of oil for replenishment of the inlet film. It is in fact usual (as shown by the convex shape of the inletzone) for oil to feed out of the inlet zone into the ribs. Oil globules were sometimes observed riding on an air cushion at the entry to the roller‐track conjunction, though completely inoperative as providers of oil.

Details

Industrial Lubrication and Tribology, vol. 33 no. 3
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 8 May 2018

Milan Omasta, Martin Ebner, Petr Šperka, Thomas Lohner, Ivan Krupka, Martin Hartl, Bernd-Robert Hoehn and Karsten Stahl

The purpose of this study is to investigate lubricant film-forming capability of oil-impregnated sintered material in highly loaded non-conformal contacts. This…

Abstract

Purpose

The purpose of this study is to investigate lubricant film-forming capability of oil-impregnated sintered material in highly loaded non-conformal contacts. This self-lubrication mechanism is well described in lightly loaded conformal contacts such as journal bearings; however, only a little has been published about the application to highly loaded contacts under elastohydrodynamic lubrication regime (EHL).

Design/methodology/approach

Thin film colorimetric interferometry is used to describe the effect of different operating conditions on lubricant film formation in line contacts.

Findings

Under fully flooded conditions, the effect of porous structure can be mainly traced back to the different elastic properties. When the contact is lubricated only by oil bleeding from the oil-impregnated sintered material, starvation is likely to occur. It is indicated that lubricant film thickness is mainly governed by oil bleeding capacity. The relationship between oil starvation parameters corresponds well with classic starved EHL theory.

Practical implications

To show practical, relevant limitations of the considered self-lubrication system, time tests were conducted. The findings indicate that EHL contact with oil-impregnated sintered material may provide about 40 per cent of fully flooded film thickness.

Originality/value

For the first time, the paper presents results on the EHL film-forming capability of oil-impregnated sintered material by measuring the lubricant film thickness directly. The present paper identifies the phenomena involved, which is necessary for the understanding of the behavior of this complex tribological system.

Details

Industrial Lubrication and Tribology, vol. 70 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 9 August 2013

Mukesh A. Bulsara, Dhananjay V. Bhatt and Kishore N. Mistry

The aim of this paper is to develop a technique to measure the oil film thickness between piston ring and liner throughout the stroke, without impairing the surface…

Abstract

Purpose

The aim of this paper is to develop a technique to measure the oil film thickness between piston ring and liner throughout the stroke, without impairing the surface properties of the piston ring and liner. Mechanical properties of the piston ring, like ring stiffness, are also not altered. Effect of variation in bore on the movement of piston ring can be studied with the proposed technique.

Design/methodology/approach

The gap Hmin between the cylinder liner and the piston ring is formed due to the hydrodynamic pressure generated by the presence of oil film between piston ring and liner. This gap can be inferred by measuring the movement of the inner surface of piston ring with reference to a sensor mounted on the piston at a fixed distance from the piston ring. The piston ring is connected to the sensor through reasonably rigid member. The underlying assumption here is that there is no elastic deformation of the piston ring due to the hydrodynamic pressure. The fundamental sensor to measure oil film thickness used in this setup is a set of strain gauges.

Findings

It is possible to measure oil film thickness by the proposed arrangement for the entire stroke without changing the surface properties. Mechanical properties of the piston ring, like ring tension, are not affected. The results possibly provide the correct picture of the piston ring movement throughout the stroke. The measurement at near zero speed can give information on the movement of the piston ring due to hydrodynamic action and to the variation in the bore. The measurement is not affected by engine vibrations. The proposed technique can be helpful in validating the theoretical models proposed in the literature.

Originality/value

The measurement is possible only in unfired condition. However, this attempt can be considered as the basis to measure OFT in fired condition with necessary improvements. It is not feasible to measure quantity of lubricant/extent of lubricant on leading or trailing edge of piston. Effect of temperature on the oil film thickness cannot be studied as the engine is not fired. It is assumed that the piston ring does not pass through elasto‐hydrodynamic lubrication regime. Debris/worn out particles in the oil may affect the indicated oil film thickness at local points.

Details

Industrial Lubrication and Tribology, vol. 65 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 30 October 2018

Yanqin Zhang, Zhiquan Zhang, Xiangbin Kong, Rui Li and Hui Jiang

The purpose of this paper was to obtain the lubrication characteristics of heavy hydrostatic bearing in heavy equipment manufacturing industry through theoretical analysis…

Abstract

Purpose

The purpose of this paper was to obtain the lubrication characteristics of heavy hydrostatic bearing in heavy equipment manufacturing industry through theoretical analysis and numerical simulation.

Design/methodology/approach

This paper discusses the influence of oil film thickness variation on velocity field, outlet-L and outlet-R flow velocity under the hydrostatic bearing running in no-load 0 N, load 400 KN, full load 1,500 KN and rotating speeds of 10 r/min, 20 r/min, 30 r/min, 40 r/min, 50 r/min and 60 r/min, by using dynamic mesh technology and FLUENT software.

Findings

When the working table rotates clockwise, in the change process of oil film thickness, the fluid flow pattern of the lubricating oil at the edge of the sealing oil is the rule of laminar flow, and the oil cavity has a vortex. The outlet-R flow velocity becomes higher and higher by increasing the bearing load and working table speed, and the flow velocity increases with the decrease in oil film thickness; the outlet-L flow velocity increases with the decrease in oil film thickness under low rotating speed (less than 10 r/min) condition and decreases with the decrease of oil film thickness under high rotating speed (more than 60 r/min) condition.

Originality/value

The influence of the oil film thickness on the flow state distribution of the oil film was analyzed under different working conditions, and the influence rules of oil film thickness on the flow velocity of hydrostatic bearing oil pad was obtained by using dynamic mesh technology.

Details

Industrial Lubrication and Tribology, vol. 71 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 16 September 2013

Mukesh A. Bulsara, Dhananjay V. Bhatt and Kishore N. Mistry

The purpose of this paper is to present a measurement technique wherein the film thickness is measured in unfired condition for entire stroke length but without impairing…

Abstract

Purpose

The purpose of this paper is to present a measurement technique wherein the film thickness is measured in unfired condition for entire stroke length but without impairing the original condition of piston ring, liner and lubricant, i.e. non-invasively. Film thickness is measured at different speeds up to 500 rpm. The measurements are initially carried out at near zero speed followed by speeds mentioned above. Measurement highlights the combined effect of variation of bore diameter and ring face profile on the film thickness.

Design/methodology/approach

The film thickness is measured with the help of a set of strain gauges. Four strain gauges are mounted on a sufficiently elastic steel strip which is mounted in a simply supported condition. This assembly of strain gauge is mounted on small rectangular bracket. A cutout is made in the piston to accommodate the bracket. A pin bearing a slot of size sufficient enough to accommodate the piston ring on one side is fixed between the piston ring and the strain gauge assembly. This ensures the transfer of the movement of the piston ring on to the strain gauge. The deflection of the strain gauge is pre-calibrated against a sufficiently accurate dial gauge. Hence any radial movement of the piston ring is sensed by the strain gauge assembly. A data logger unit is connected to the strain gauge output to log the data at every crank angle. A rotary encoder is connected to the crank shaft, to have the correlation of the strain gauge output with the crank angle.

Findings

The technique is capable of measuring oil film thickness for entire stroke at low speeds in unfired engines. The effect of variation in bore diameter on the oil film thickness is significant and hence such measurement can enlighten the path for research to reduce friction. The experimental results of the oil film thickness are in good agreement with predicted values, particularly in the forward stroke (BDC to TDC).

Research limitations/implications

The methodology is not suitable for fired engines as on date but can be taken up as a future work with necessary modifications. It does not take into consideration the effect of elasto-hydrodynamic lubrication.

Practical implications

It can be used to measure OFT between piston ring and liner in unfired engines and reciprocating compressors also.

Social implications

It can help to indentify the areas of research so that the friction between piston ring and liner can be reduced thus increasing efficiency of the engine and reducing fuel consumption and emissions.

Originality/value

The work presented is a part of PhD work under progress at S V National Institute of Technology, Surat, India. The setup is in the college premises and the experiments are conducted on the same.

Details

Industrial Lubrication and Tribology, vol. 65 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 13 October 2020

Haiji Wang and Guanglin Shi

The purpose of this paper is to propose an adjustable oil film thickness test rig for detecting lubrication characteristics of the slipper. The mathematical analysis of…

Abstract

Purpose

The purpose of this paper is to propose an adjustable oil film thickness test rig for detecting lubrication characteristics of the slipper. The mathematical analysis of lubrication is introduced. Based on the results from the test rig, the results comparison from test rig and mathematical analysis is carried out.

Design/methodology/approach

This paper introduces a mechanism which can adjust the oil film thickness between the slipper and swash-plate. Feasibility is ensured, and the accuracy of test rig is guaranteed by the three-coordinate measuring machine. Three displacement sensors show the oil film thickness and its shape. The reacting force and torque resulting from oil film can be achieved by three S-type force sensors and a torque sensor, respectively.

Findings

The relative error of the reacting force is small. The relative error reduces and is acceptable when the deformation of retainer is taken into account. The thickness and tilt angle of oil film have less effect on the reacting force. However, they are significantly impact on torque.

Originality/value

The test rig proposed in this paper is able to adjust the oil film thickness, which is used to detecting the lubrication characteristics in pump design.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2020-0166/

Details

Industrial Lubrication and Tribology, vol. 73 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 19 July 2019

Yanqin Zhang, Jichang Sun, Pengrui Kong, Xiangbin Kong and Xiaodong Yu

The purpose of the paper is to analyze the bearing capacity of hydrostatic bearing during the change of film thickness under different working conditions and to improve…

Abstract

Purpose

The purpose of the paper is to analyze the bearing capacity of hydrostatic bearing during the change of film thickness under different working conditions and to improve the processing efficiency and precision of equipment.

Design/methodology/approach

In this study, Q1-205 double rectangular cavity hydrostatic thrust bearing is selected as the research object. The dynamic mesh method and ANSYS/FLUENT software are used to simulate the curves of oil film thickness and oil pressure under different operating conditions. Finally, the change of pressure in the oil cavity at different operating speeds under a certain inlet flow rate was tested through design experiments.

Findings

When the film thickness was thick, the maximum pressure in the oil cavity at different inlet velocities showed little difference. With a larger inlet flow, the maximum pressure in the oil cavity was higher. The pressure at the edge of the oil seal was linearly distributed. The oil pressure in the downstream side was greater than that in the counter flow side. When the working pressure was low, the pressure in the oil cavity slightly decreased with the increase of working speed. Moreover, the pressure loss at high speed was considerable.

Originality/value

Based on the lubrication theory, the mathematical model of the bearing oil film was set up. The bearing capacity equation of the hydrostatic cavity was derived. The double-rectangular-annular hydrostatic guides studied in this paper have not been reported in previous research literature and the method of dynamic mesh dynamic simulation of variable viscosity is seldom studied before. The bearing characteristics and the change of oil film thickness under different working conditions have been studied systematically and comprehensively. The theoretical analysis results are basically consistent with the experimental results.

Details

Industrial Lubrication and Tribology, vol. 71 no. 9
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 10 August 2018

Baogang Wen, Hongjun Ren, Pengfei Dang, Xu Hao and Qingkai Han

The oil film thickness provides a key performance indicator of a ball bearing lubrication condition. This paper aims to propose an approach to calculate and measure the oil

Abstract

Purpose

The oil film thickness provides a key performance indicator of a ball bearing lubrication condition. This paper aims to propose an approach to calculate and measure the oil film thickness of the bearing.

Design/methodology/approach

On a specially designed test rig, measurement of the capacitance is used to monitor the oil film thickness of ball bearing. A corrected film thickness formula taking account of the influences of non-Newtonian shear thinning and thermal is introduced to predict the oil film thickness of ball bearing. And then the film thickness distribution and the corresponding capacitances are calculated.

Findings

Measurement and calculation of oil film thickness in a ball bearing are carried out under various rotating speeds and external loads. By comparing the calculated capacitances with measured results, it can be concluded that the calculated results obtained by the amended film thickness formula are much closer to the test findings than the classical computed values according to Hamrock–Dowson.

Originality/value

A new corrected film thickness formula is introduced in predicting oil film thickness of ball bearing and verified by the series of experiments according to capacitance method.

Details

Industrial Lubrication and Tribology, vol. 70 no. 8
Type: Research Article
ISSN: 0036-8792

Keywords

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