A Refined Analytical Model for Hydrodynamic Lubrication of Cold Extrusion and Its Comparison With Experiment

1982 ◽  
Vol 104 (1) ◽  
pp. 46-52 ◽  
Author(s):  
S. M. Mahdavian
Keyword(s):  
Analytical Model ◽  
Castor Oil ◽  
Hydrodynamic Lubrication ◽  
Work Zone ◽  
Extrusion Pressure ◽  
Cold Extrusion ◽  
Viscous Heating ◽  
Theoretical Estimation ◽  
Comparison With Experiment ◽  
Inlet Zone

In a refined analytical model for the hydrodynamic lubrication of cold extrusion, effects of viscous heating in the inlet zone and surface temperature in the work zone are included to estimate extrusion pressure for both unsteady and steady lubrication. An experimental study indicates that a hydrodynamic lubricant film may be formed by reducing friction at the start of extrusion by a secondary lubricant. Theoretical estimation of unsteady extrusion pressure is in agreement for extrusion of aluminium billets lubricated with castor oil.

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.

Evolution of Surface Pits on Stainless Steel Strip in Cold Rolling and Strip Drawing

2003 ◽  
Vol 125 (2) ◽  
pp. 384-390 ◽  
Author(s):  
H. R. Le ◽  
M. P. F. Sutcliffe
Keyword(s):  
Stainless Steel ◽  
Cold Rolling ◽  
Hydrodynamic Lubrication ◽  
Steel Strip ◽  
Theoretical Models ◽  
Finite Depth ◽  
Work Zone ◽  
Oil Film ◽  
Strip Drawing ◽  
Inlet Zone

Theoretical models are presented for describing the evolution of pits in the inlet and work zone during cold rolling and strip drawing of shot-blast stainless steel under ‘mixed’ lubrication. Results shows that the rough shot-blast surface is flattened rapidly in a short inlet zone, thereby entrapping the lubricant in surface pits. The subsequent evolution of these surface pits in the work zone can be explained by micro-plasto-hydrodynamic-lubrication (MPHL) models described previously. A development of these models is presented which takes into account the effects of the oil film entrained in the inlet, an oil film penetrating from adjacent pits and the finite depth of the pits. The role of an inlet oil film and penetrating MPHL oil film is to limit the potential reduction of pit size. Lubrication regime maps are constructed which describe the evolution of the surface pits for a range of pit geometries. Results explain the experimental observation that some pits survive even after a multi-pass schedule. Predictions of the pit area show good agreement with measurements on samples obtained in strip drawing or rolled under industrial conditions.

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.

Partial Film Lubrication Characteristics of Inlet Zone in Cold Strip Rolling

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Kuo Fu ◽  
Yong Zang ◽  
Zhiying Gao
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Contact Area ◽  
Friction Stress ◽  
Area Ratio ◽  
Work Zone ◽  
Zone Length ◽  
Inlet Zone ◽  
Pressure Stress ◽  
Contact Area Ratio

According to the average flow Reynolds equation and rolling theory, a partial film lubrication model of inlet zone has been developed. The model mainly simulates and reflects the influence of surface topography on the inlet film thickness and inlet zone length. Based on the surface topography analysis, a method to judge the friction condition was proposed. All the calculation was conducted by a numerical method. The result shows that the transverse stripe increases the inlet film thickness and the inlet zone length, while the longitudinal stripe decreases them. The surface roughness will enhance this effect. The surface roughness and the stripe direction also have a significant influence on the contact area ratio and the distribution of stress and film thickness in work zone. Transverse stripe increases the lubricant film thickness and separates the roll and the sheet with a larger distance in work zone. It also decreases the contact area ratio, the pressure stress and friction stress of the work zone. Whereas longitudinal stripe decreases the film thickness and increases the contact area ratio, pressure stress and friction stress. The surface roughness increases the contact area ratio, pressure stress and friction stress.

Isoviscous Hydrodynamic Lubrication of Deep Drawing and Its Comparison With Experiment

1993 ◽  
Vol 115 (1) ◽  
pp. 111-118 ◽  
Author(s):  
S. M. Mahdavian ◽  
Z. M. Shao
Keyword(s):  
Film Thickness ◽  
Deep Drawing ◽  
Hydrodynamic Lubrication ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Blank Holder ◽  
Comparison With Experiment ◽  
Force Ratio ◽  
Theoretical Predictions ◽  
Metal Blank

An analytical model for the isoviscous hydrodynamic lubrication of deep drawing is developed. The model covers the complete drawing stages from sheet metal blank to the drawn cup-shaped product. Equations to calculate the film thickness, radial, and drawing stresses related to the blank holder squeezing action are presented. Theoretical predictions of both film thickness and drawing force ratio for lubricated, low carbon steel are compared with experimental measurements.

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.

scholarly journals Numerical Study of Power Loss and Lubrication of Connecting Rod Big-End

Lubricants ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 47 ◽  
Author(s):  
Abbas Razavykia ◽  
Cristiana Delprete ◽  
Paolo Baldissera
Keyword(s):  
Analytical Model ◽  
Power Loss ◽  
Numerical Study ◽  
Hydrodynamic Lubrication ◽  
Computation Time ◽  
Hydrodynamic Pressure ◽  
Mobility Model ◽  
Accurate Estimation ◽  
Connecting Rod ◽  
Numerical Effort

A hydrodynamic lubrication analysis for connecting rod big-end bearing is conducted. The effects of engine speed, operating condition, lubricant viscosity and oil temperature on tribological performance of big-end bearing have been examined. Force equilibrium is solved to define instantaneous eccentricity between journal and bearing to have accurate estimation of oil film thickness at interface of connecting rod big-end bearing and crankpin. Connecting rod big-end is treated as π film hydrodynamic journal bearing and finite difference scheme is applied to calculate generated hydrodynamic pressure and frictional power loss at each crank angle. Beside the development of analytical formulation, well-known Mobility model introduced by Booker has been employed to be compared with the analytical model. The presented analytical model reduces the complexity and the numerical effort with respect to Mobility method, thus shortening the computation time. The simulation results show good agreement between analytical model, Mobility approach and experimental data.

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