scholarly journals Discussion: “Isothermal Hydrodynamic Lubrication in Hydrostatic Extrusion of a Work-Hardening Material” (Thiruvarudchelvan, S., 1979, ASME J. Lubr. Technol., 101, p. 386)

1980 ◽  
Vol 102 (2) ◽  
pp. 257-257
Author(s):  
W. R. D. Wilson
Keyword(s):  
Work Hardening ◽  
Hydrodynamic Lubrication ◽  
Hydrostatic Extrusion ◽  
Hardening Material

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.

An Experimental Investigation of Lubrication in Hydrostatic Extrusion Using Wax as a Model Material

1972 ◽  
Vol 94 (3) ◽  
pp. 913-919 ◽  
Author(s):  
A. Wuerscher ◽  
W. B. Rice
Keyword(s):  
Thin Film ◽  
Castor Oil ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Pressure Fluctuations ◽  
Model Material ◽  
Hydrostatic Extrusion ◽  
Strain Rates ◽  
The Coefficient Of Friction ◽  
Bearing Friction

This paper describes hydrostatic extrusion experiments in which paraffin wax was extruded, undertaken to test the validity of a theory proposed by Iyengar and Rice concerning the conditions necessary for hydrodynamic lubrication. Three fluids were used: castor oil, and two silicone fluids. Stress-strain curves obtained at several strain rates revealed that the particular wax behaves like many metals in that Y = Aεm. Strain-rates in the die are assessed, and corresponding values of Y are incorporated in the Hoffman and Sachs analysis of extrusion, which is then used to estimate the coefficient of friction from observed values of extrusion pressure. Analogy with journal bearing friction phenomena leads to the conclusion that at higher speeds hydrodynamic lubrication was attained with all three fluids, but that it was “thin-film” rather than “thick-film” predicted for similar billet speeds. Violent pressure fluctuations observed at higher speeds with castor oil, but not with the silicone fluids are attributed to smaller compressibility and viscosity of the castor oil.

A Thermal Hydrodynamic Lubrication Theory for Hydrostatic Extrusion of Low Strength Materials

1976 ◽  
Vol 98 (2) ◽  
pp. 335-342 ◽  
Author(s):  
R. W. Snidle ◽  
B. Parsons ◽  
D. Dowson
Keyword(s):  
Plastic Deformation ◽  
Theoretical Analysis ◽  
Thermal Effects ◽  
Hydrodynamic Lubrication ◽  
Extrusion Process ◽  
Lubrication Theory ◽  
Lubricant Film ◽  
Hydrostatic Extrusion ◽  
Solid Friction ◽  
Hydrodynamic Lubrication Theory

The paper presents a theoretical analysis of hydrodynamic lubrication in the hydrostatic extrusion process which includes a consideration of thermal effects in the lubricant film arising from the work of plastic deformation. A Newtonian lubricant with an exponential pressure-temperature-viscosity relationship has been assumed and allowance has been made for the effects of redundant deformation of the worked material. The results of the theory are compared with those from previous isothermal and solid friction theories.

An Elasto-Plasto-Hydrodynamic Lubrication Analysis of the Hydrostatic Extrusion Process

1973 ◽  
Vol 95 (2) ◽  
pp. 113-122 ◽  
Author(s):  
R. W. Snidle ◽  
D. Dowson ◽  
B. Parsons
Keyword(s):  
Plastic Deformation ◽  
Thermal Effects ◽  
Preliminary Analysis ◽  
Hydrodynamic Lubrication ◽  
Numerical Procedure ◽  
Extrusion Process ◽  
Lubricant Film ◽  
Hydrostatic Extrusion ◽  
Small Influence ◽  
Theoretical Results

The authors describe a numerical procedure for the solution of the problem of hydro-dynamic lubrication in the hydrostatic extrusion process. The lubricant is assumed to be a Newtonian fluid and in this preliminary analysis it is assumed that the yield strength of the worked material remains constant. Elastic deformation of the billet as it enters and leaves the die is considered but this effect is found to have only a small influence upon the thickness of the lubricant film which is generated. Thermal effects arising from plastic deformation of the billet and viscous dissipation in the lubricant film are also considered. Theoretical results are presented showing the influence of die angle and reduction ratio upon values of film thickness and extrusion pressure for two materials.

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