In cold rolling of thin strips, i.e., foils (Thickness<50µm), it is important to take into account the flattening of the roll surfaces. The displacement of the roll surface is obtained by combining some results from the well-known Hertzian theory of contact mechanics and roll-modeling as a system of springs with different spring constants within contact conjunction. Use of lubricants can reduce rolling force and improve surface properties of the foil. Depending on the lubricant properties and rolling speed, either hydrodynamic lubrication or mixed lubrication regimes can prevail. The present theoretical work is focused upon the influence of the rolling-process parameters like rolling speed, reduction ratio, roll surface roughness and lubricant viscosity on the friction coefficient and film thickness in the roll bite in the mixed lubrication regime. Results show that with increase of viscosity, rolling force decreases and film thickness increases. تفاصيل المقالة

Carbon nanotubes have an important role in reinforcing nanocomposits. Many experimental observations have shown that in the most nanostructures such as nanocomposites, carbon nanotubes (CNTs) are often characterized by a certain degree of waviness along their axial direction. In the present paper, the effects of initial curvature, influence of surrounding medium that is modeled as Winkler elastic foundation on behavior of slightly curved carbon nanotubes are investigated. To capture the small size effects, nonlocal elasticity theory is implemented. Bending governing equations are derived using the principle of minimum total potential energy and these nonlinear equations are solved by Newton Raphson method. It is shown that the larger the initial curvature, the higher deflection can occur. Furthermore, neglecting the effect of initial curvature of CNTs can lead to incorrect results. تفاصيل المقالة

In this paper, the wear of work roll in hot plate rolling is introduced and the parameters affecting wear mechanisms in hot strip mill are investigated. In addition, different wear mechanisms in hot rolling and the differences between these mechanisms in different stands are explained. Using the finite element method and the rolling equations, a work roll wear model is proposed. Wear is modeled using the resultant pressure distribution along the roll barrel. To obtain the tentative coefficient, summation of wear in each pass schedule is obtained and calibrated via actual wear of samples tested in the Mobarakeh Steel Company. Finally, the theoretical wear values are compared with those of the experiment. The predicted wear profiles are found to be in good agreement with those of the experimental measured values. تفاصيل المقالة

In this research a final element model for simulating three dimensional deformation in rolling of flat product is modeling in ABAQUS and further developed to study the frictional effects on spread and bulge. To predict the magnitude of bulging , the rolling process is approximated by successive forging steps. The elongation or the average spread at each step from the previous calculations are used in the model. The theoretical results of the model is in a good agreement with the experimental values given by other investigation. تفاصيل المقالة