A new method for predicting the three-dimensional surface texture transfer in the skin pass rolling of metal strips

Effect of the elastic deformation of rolls on the surface texture transfer in skin-pass rolling

Skin-pass rolling (or temper rolling) is the final operational step in the production chain of hot-rolled strips, and its main role is to apply a small deformation to the hot-rolled strips cooled to room temperature to improve the shape quality and mechanical properties. Because of the absence of rolling lubricants between the work roll and strip as well as the existence of obvious oxide layer on the strip surface, the wear of work roll is very serious, which exerts an adverse effect on the shape control precision of hot-rolled strips. In this study, the wear law of work roll is obtained by a theoretical analysis of roll wear mechanisms as well as an elastic-plastic finite element analysis of skin-pass rolling. Using the above-mentioned wear law, a work roll wear model is constructed with parameters optimized by the three-population particle swarm optimization and differential evolution algorithm. The newly established wear model is validated experimentally in the field. Calculated values coincide well with those obtained from experiment. The wear model can be used for guiding the actual production.

Study on mathematical model of work roll wear in skin-pass rolling of hot steel strip

https://ro.uow.edu.au/cgi/viewcontent.cgi?article=3550&context=eispapers1

Analysis of surface roughness alteration in micro flexible rolling

Automobile and household appliance panels require steel strips with extremely high-quality surfaces. Therefore, an in-depth study of the surface topography transfer of the steel strip during the rolling process is of considerable significance for improving product quality. In this study, the scale-invariant feature transform (SIFT) algorithm is used to realize the large-field stitching and the correspondence measurement of the surface topography of the roll and strip. The surface topography transfer mechanism and microconvex change law during cold rolling are revealed. Further analysis is conducted regarding the effects of different reduction rates and the initial surface topography of the roll on the formation of strip surface topography. Experimental results reveal that the furrow phenomenon occurs during the rolling process owing to the backward slip effect but is eliminated by the elastoplastic deformation of the matrix and the forward slip action. No furrow occurred along the width direction of the strip. With an increase in the rolling reduction rate, the transfer rate increases, and the strip surface topography is closer to the roll surface topography. Under the same rolling roughness condition and a small reduction rate (5%), the transfer degree increases remarkably with a rise in the reduction rate and increases slowly as the reduction rate continues to grow (from 7 to 10%). This study serves as a theoretical basis for the subsequent improvement of the surface quality of cold rolled strips.

An Experimental Investigation of Steel Surface Topography Transfer by Cold Rolling

The surface of sheet metals should have a certain level of roughness in terms of forming and dyeing quality. Surface roughness is mainly introduced to the material by rolling with rough rolls, which is called temper rolling. The roughness of a roll is transferred to the material, depending on the rolling parameters. A 2-high rolling setup equipped with a load-cell measuring the rolling force, which can roll at different speeds and reduction ratios, was used to observe the change in the amount of roughness transfer. Surface roughness values of specimens were measured after tests, their average and standard deviation values were calculated, and 3-D field scanning images were investigated. The results obtained were evaluated in terms of rolling parameters and roughness transfer. It was concluded that each parameter that increased the rolling force also increased the roughness transfer. It was seen that rolling force, and thus roughness transfer, was higher in the tests conducted at high speeds and high reduction ratios with thinner materials. Lubricated roughening tests indicated that the introduction of roughness on material surface decreased due to lubrication. Moreover, a more homogeneous roughness distribution was obtained in lubricated rolling compared to dry rolling. It was observed that the roughness at small reduction ratios was obtained within a narrower range.

An experimental investigation into roughness transfer in skin-pass rolling of steel strips

The last stage of the cold rolling process is skin-pass rolling and one of its most significant goals is to obtain appropriate topography on the surface of the sheet steel used extensively such as in automotive industry. The purpose of this paper is to investigate the effect of thickness change and various reduction ratios on roughness transfer of DC04 grade sheet material.,DC04 grade sheet materials with different reduction ratios and several thicknesses were subjected to skin-pass rolling process in the rolling equipment with a two-high roll. Some roughness parameters were determined as a result of roughness measurements from the surfaces of roughened sheet materials.,While the roughness transfer is higher in 1-mm thick material in reduction ratios up to 430 micrometers; in reduction ratios above 430 micrometers, it is higher for 1.5-mm thick materials. As the reduction ratio increases in DC04 grade sheet materials, the homogeneity of the roughness distribution in 1-mm thickness sheet material deteriorates, while the roughness distribution in 1.5-mm thickness sheet material is more homogeneous.,This paper demonstrates how material thickness and reduction ratio affect the roughness transfer in skin-pass rolling. The results obtained can be used by optimizing in manufacturing processes.

Effect of material thickness and reduction ratio on roughness transfer in skin-pass rolling to DC04 grade sheet materials

When producing cold-rolled steel sheets, the penultimate annealing process is followed by a final skin-pass rolling (or temper rolling) whose purpose is to eliminate any discontinuous yielding whic...

Bilal Çolak

Papers

An experimental investigation into roughness transfer in skin-pass rolling of steel strips

Effect of material thickness and reduction ratio on roughness transfer in skin-pass rolling to DC04 grade sheet materials

How the skin-pass rolling reduction ratio affects the strain aging behaviour of low-carbon steel sheets