Shot Blasting Process Schematization for Rollers Using Slip-Line Method

The considered theoretical analysis of the roughness parameters formation of the rolling face of the pinch pass mills, when they are indented with shot, allows to obtain more adequate and convenient theoretical results for use in practice. The formation of a rough layer on the rolling working surface of the pinch pass mill is determined by the impact and penetration of the shots into its surface. When this occurs, the elastic and plastic deformation of the roll materials and shot with the dimple formation and the displacement of a portion of the deformed roll material on the edges of this dimple takes place. The obtained results allow using the mathematical dependencies to control purposefully the process of shot blasting and correct it when texturing the working rolling faces of the pinch pass mills.

Optimization Technology of Roll Contours during Skin-Pass Rolling Process of Hot-Rolled Strip

The hot-rolled strip skin-pass mill is the important technological equipment of finishing process in the hot rolling plant, and its role is to apply a slight thickness reduction of approximately 1% - 4% to the finished products cooled to room temperature to repair flatness defects and improve the surface quality and mechanical properties. In this study, the initial flat roll contours were optimized to solve some problems such as the serious and non-uniform wear of work rolls and the poor shape control abilities of the strip. A three-dimensional rolls–strip coupling model of hot-rolled strip skin-pass mill was established using the nonlinear finite element software ABAQUS. The effects of the roll contours on the contact pressure between rolls and the control effect of bending forces were analyzed, and a variable contact-length backup roll (VCR) contour configured with a positive crown contour for work rolls was proposed. Compared with the initial flat roll contours, the average replacement cycle of work rolls for the optimized roll contours increased from 465.4 tons to 701.3 tons, the non-uniform wear amount was reduced by nearly 15%, and the adjustment ratio of the negative bending forces decreased from -100% to -40% by industrial experiments in the 1580 mm single-stand four-high hot-rolled strip skin-pass mill.

Numerical Simulation and Analysis for Blow-Off Flow Field of a Wet Skin Pass Mill

Blow-off air nozzles blow away the residual emulsion from roll gap and strip surface. Algorithm SIMPLY were used for the finite element numerical simulation for a representational air nozzle blow-off flow field near the roll gap in a cold-rolled skin pass mill. The working conditions of the blow-off flow field was the combination of gas pressure of 0, 2, 5 and 10bar and flip angle of 0°, 5°, 10°, 15°, 20° and 25°. The study provides a reference for control and optimization for the removal process of residual emulsion and design, manufacture, model selection and optimization for the related air nozzles.