Isothermal Hydrodynamic Lubrication in Hydrostatic Extrusion of a Work-Hardening Material

1979 ◽  
Vol 101 (3) ◽  
pp. 386-389 ◽  
Author(s):  
S. Thiruvarudchelvan
Keyword(s):  
Film Thickness ◽  
Pressure Distribution ◽  
Numerical Method ◽  
Work Hardening ◽  
Critical Speed ◽  
Hydrodynamic Lubrication ◽  
Hydrostatic Extrusion ◽  
Extrusion Pressure ◽  
Hydrodynamic Conditions ◽  
Hardening Material

Using a numerical method the film thickness and the pressure distribution in hydrostatic extrusion of a work-hardening material under hydrodynamic conditions are determined. A minimum or critical speed for full fluid lubrication to develop is predicted. The effect of the length of die-land on the critical speed, and the effect of speeds above the critical speed on the extrusion pressure are also presented.

The elasto-hydrodynamic lubrication of rollers

1961 ◽  
Vol 262 (1308) ◽  
pp. 51-72 ◽  
Keyword(s):  
Film Thickness ◽  
Pressure Distribution ◽  
Experimental Evidence ◽  
Digital Computer ◽  
Iterative Procedure ◽  
Hydrodynamic Lubrication ◽  
Pressure Coefficient ◽  
Lubricating Oil ◽  
Coefficient Of Viscosity ◽  
Theory And Experiment

Gears rollers frequently operate at loads sufficient to deform them appreciably and to enhance the viscosity of the lubricating oil in the region of closest contact. No rigorous theory of this state of lubrication has been available hitherto. In this paper an iterative procedure is developed and has been followed with a digital computer. The calculations yield the oil film thickness, the pressure distribution and the shape of the deformed system. Solutions are given showing the effect of load and speed; the influence of the pressure coefficient of viscosity of the oil, and of the elasticity of the rollers is also shown. The main feature of the results is the prediction of peaks of pressure on the outlet side of the system, the height of the peaks depending greatly upon the foregoing variables. The theory is compared with the available experimental evidence and though it is a clear improvement upon earlier theories, significant differences between theory and experiment yet remain. The origin of these differences is discussed and it is concluded that there is greater need at the present time for fuller experimental evidence than for further elaborations in the theory.

Thermoelastic Instability With Consideration of Surface Roughness and Hydrodynamic Lubrication

1999 ◽  
Vol 122 (4) ◽  
pp. 725-732 ◽  
Author(s):  
J. Y. Jang ◽  
M. M. Khonsari
Keyword(s):  
Thermal Conductivity ◽  
Surface Roughness ◽  
Film Thickness ◽  
Hot Spots ◽  
Critical Speed ◽  
Hydrodynamic Lubrication ◽  
Lubricant Film Thickness ◽  
Governing Equations ◽  
Thermoelastic Instability ◽  
Liquid Lubricant

An idealized model consisting of a surface with high thermal conductivity separated by a film of liquid lubricant from a rough surface with low thermal conductivity is developed to study thermoelastic instability. The governing equations are derived and solved for the critical speed beyond which thermoelastic instability leading to the formation of hot spots is likely to occur. A series of dimensionless parameters is introduced which characterizes the thermoelastic behavior of the system. It is shown the surface roughness and the lubricant film thickness both play an important role on the threshold of instability. [S0742-4787(00)00104-1]

Lubrication Phenomena in Spur Gears: Capacity, Film Thickness Variation, and Efficiency

1965 ◽  
Vol 87 (3) ◽  
pp. 655-663 ◽  
Author(s):  
R. Wayne Adkins ◽  
E. I. Radzimovsky
Keyword(s):  
Shear Stress ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Power Loss ◽  
Hydrodynamic Lubrication ◽  
Thickness Variation ◽  
Spur Gears ◽  
Oil Film ◽  
Lubrication Conditions ◽  
Lubricant Viscosity

In this paper the oil film separating the mating surfaces of involute spur gears operating under hydrodynamic lubrication conditions is analyzed. This analysis surpasses previous analyses in as much as the actual motion of the involute profiles (rolling, sliding, and squeezing motion) and the total number of teeth engaged at any one time are considered. Expressions are derived for the pressure distribution, shear stress, and power loss in the oil film at any phase of tooth engagement. A method is developed by which these expressions can be applied to determine the film thickness at any instant and the power loss for a given load, speed, and lubricant viscosity.

A Simulation of Hydrodynamic Lubrication on Non-Glazed Surfaces under Different Sliding Velocities and Loads

2007 ◽  
Vol 353-358 ◽  
pp. 827-830
Author(s):  
Peng Li ◽  
Jian Li ◽  
Yong Zhen Zhang ◽  
M. Scherge
Keyword(s):  
Wear Resistance ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Hydrodynamic Lubrication ◽  
Maximum Pressure ◽  
Minimum Film Thickness ◽  
Pin On Disk ◽  
Lubrication Conditions

Recent researches have found that surfaces with non-glazed or laser dimpling topography offer improved lubricating efficiency and wear resistance under lubrication conditions over their conventional glazed status. It was carried out in this paper to simulate a pin-on-disk experimental condition and perform hydrodynamic lubrication (HL) calculations for both non-glazed and glazed surfaces under conditions of different sliding velocities and loads with a view of understanding the tribological mechanism and characteristics of non-glazed surfaces. The results showed that the minimum film thickness of non-glazed surfaces, which closed to a typical elasto-hydrodynamic lubrication (EHL) film thickness, was thicker than that of glazed surfaces under the condition of low sliding velocities and small loads. At the same time, a decreased maximum pressure of full-film of non-glazed surfaces demonstrated an even pressure distribution on them.

Hydrodynamic Lubrication of Hydrostatic Extrusion

1976 ◽  
Vol 98 (1) ◽  
pp. 27-31 ◽  
Author(s):  
W. R. D. Wilson ◽  
S. M. Mahdavian
Keyword(s):  
Film Thickness ◽  
Castor Oil ◽  
Hydrodynamic Lubrication ◽  
Film Formation ◽  
Hydrostatic Extrusion ◽  
Work Zone ◽  
Thickness Variation ◽  
Viscous Heating ◽  
Theoretical Predictions ◽  
Good Agreement

An analytical model for the hydrodynamic lubrication of hydrostatic extrusion is developed. This includes the effect of viscous heating on the film formation process and the effect of viscous and plastic heating on the friction and film thickness variation in the work zone. Theoretical predictions of film thickness and extrusion pressure show good agreement with experimental measurements for aluminum billets lubricated with castor oil.

Inverse Hydrodynamic Methods Applied to Mr. Beauchamp Tower’s Experiments of 1885

1980 ◽  
Vol 102 (2) ◽  
pp. 172-179 ◽  
Author(s):  
C. M. McC. Ettles ◽  
M. Akkok ◽  
A. Cameron
Keyword(s):  
Film Thickness ◽  
Pressure Distribution ◽  
Hydrodynamic Lubrication ◽  
Pressure Profile ◽  
Hydrodynamic Theory ◽  
Two Dimensional ◽  
Hydrodynamic Analysis ◽  
Cubic Equation ◽  
Hydrodynamic Lubrication Theory ◽  
Measured Pressure

The experiments of Mr. Beauchamp Tower and their subsequent interpretation by Professor Osborne Reynolds form the basis of all hydrodynamic lubrication theory. In the experiments described in his second report, Tower made nine pressure tappings in a 157 deg partial arc bearing. Reynolds assumed that the film shape corresponded to a circular bearing and analyzed the results on this assumption. Inverse hydrodynamic theory allows the calculation of the actual film shape from this measured pressure distribution. It is found that the film was a slightly convergent wedge which does not correspond to a fitted bearing as assumed by Tower and certainly not to the clearance bearing assumed by Reynolds. Existing methods of inverse hydrodynamic analysis require the second differential of the pressure profile (or its equivalent in the two-dimensional case) to become zero at some point in the film. The film thickness can be found directly at this point and then elsewhere by the solution of a cubic equation. Two separate and more general methods are developed in this paper in which this requirement for the second differential is unnecessary.

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