Local approach strategy to predicting final roughness in cold rolling of stainless steel strips

Abstract

Good surface finish is an important requirement for many stainless steel products essentially in terms of brightness. This article deals with an original numerical approach proposed in order to better control workpiece roughness during cold rolling. As a first step, to supply the numerical model, the blasted strip rheology is identified using an inverse finite element methodology based on Vickers indentations. As a second step, a fluid-structure strong coupling model is proposed to determine the flattening of steel strip asperities during the first passes of a cold rolling sequence. Fluid flowrate between each valley is solved using local Reynolds' equations. The volume of the lubricant trapped and its pressure are updated on the cold rolling model. At the same time, asperities are deformed from the entry to the exit to reach their final shape. Roughness sensitivity to the industrial process parameters, to the rheological parameters, and to the lubricant rheology is discussed.

Analysis of fluid lubrication mechanisms in metal forming at mesoscopic scale

“…The numerical methodology developed in [5] involves a fully coupled fluid-structure computation for its initialization, performed on the commercial Finite Element (FE) code ABAQUS/Standard, without lubricant exchange, followed by a computation loop including two calculation steps. The first step is performed by an external subroutine computing the fluid supply to or leakage from the lubricant reservoirs (so-called cavities or pockets in the following) according to the current pressure in the pockets and the relative velocity between die and asperity plateau.…”

“…The present work involves numerical as well as experimental analysis of the lubrication mechanisms, applying the numerical strategy developed by Deltombe et al [5] to quantify the final shape of the lubricant pockets, taking into account both the hydrostatic and the hydrodynamic behaviour of the lubricant. The strategy is based on a weak fluid/structure coupling involving the Finite Element Method (FEM) and analytical calculations.…”