Research and Application of Non-symmetrical Roll Bending Control of Cold Rolling Mill

The existing research of the flatness control for strip cold rolling mainly focuses on the calculation of the optimum adjustment of individual flatness actuator in accordance with the flatness deviation, which can be used for general flatness control. However, it does not work for some special rolling processes, such as the elimination of ultra single side edge-waves and the prevention of strip break due to tilting roll control overshooting. For the purpose of solving these problems, the influences of non-symmetrical work roll bending and intermediate roll bending on flatness control were analyzed by studying efficiencies of them. Moreover, impacts of two kinds of non-symmetrical roll bending control on the pressure distribution between rolls were studied theoretically. A non-symmetrical work roll bending model was developed by theoretical analysis in accordance with practical conditions. The model was applied to the revamp of a 1250 6-H reversible universal crown mill (UCM) cold mill. Theoretical study and practical applications show that the coordination utilization of the non-symmetrical work roll bending control and tilting roll control was effective in flatness control when there appeared bad strip single side edge waves, especially when the incoming strip was with a wedge shape. In addition, the risk of strip break due to tilting control overshooting could be reduced. Furthermore, the non-symmetrical roll bending control can reduce the extent of uneven distribution of pressure between rolls caused by intermediate roll shifting in flatness control and slow down roll wear. The non-symmetrical roll bending control technology has important theoretical and practical significance to better flatness control.

Computer simulation of rolling wear on bionic non-smooth convex surfaces

The study of bionics has found that the skins of many burrow animals which live in soil and stone conditions have an anti wear function, and which is related to their body surfaces’non-smooth morphology. In the present study, bionic non-smooth surfaces are used in roll surface design, and roll models with convex non-smooth surfaces are developed. The rolling wear of non-smooth roll in steel rolling is simulated by the FEM software-ANSYS. The equivalent stress, the node friction stress, and the node contact pressure between the roll and the rolling piece are calculated; and the anti-wear mechanism is analyzed.

Roll wear on finishing trains of ASP1700 hot strip mills

A great deal of research and practical production indicated that a perfectshape control system needs a precise prediction model of roll wear. According to the practical wearcurve of work roll in Angang ASP1700 hot strip mill, which was measured by a roll-profilemeter, themodel of wear curve caused by one single strip was established. The prediction of work-roll wear wasachieved by combining Fortran language and practical technology parameters. The calculated resultsagreed well with the measured.

Multi-objective optimization for roll shifting strategy in cross rolling campaigns of hot strip mill

A multi-objective optimization approach for the roll shifting strategy in cross rolling campaigns of hot strip mills is presented. The effect of different roll shifting strategies on roll wear contour is studied by numerical simulation, and two evaluation indexes ,namely body smoothness and edge smoothness, are proposed. The average body smoothness and average rolling edge smoothness of all strips in a rolling campaign are taken as the objective functions, the shifting positions of all wide strips as the decision variables, and the multi-objective method of NSGA-II as the optimizer. Thus a multi-objective optimization model for the roll shifting strategy is built. The simulation results show that work roll shifting can make wear contour smooth,and a dish-shaped wear contour without severe local wear can be achieved by the roll shifting strategy with varying stroke. Optimization experimentation shows that by means of NSGA-II,a good Pareto-optimal front can be obtained, which suggests a series of alternative solutions for roll shifting strategy optimization. The experimentation also shows that there is a conflict between the two objectives. Finally, application cases confirm the feasibility of the multi-objective approach, which can improve the strip profile ,reduce edge waves and extend the rolling miles of a rolling campaign.

EXPERIMENTAL STUDY ON TRIBOLOGICAL PROPERTIES OF FULLERENE COPOLYMER NANOBALL

A novel fullerene-styrene-maleic anhydride copolymer is reported. TEM analyses shows it is water- soluble nanoball of average diameter of about 83 nm. The tribological behavior is evaluated by foul-ball machine. It was found that addition of fullerene copolymer to base stock (2%triethanolamine aqueous solution)resulted in a raise in load-carrying ability(F value)from 130 N to maximum 480 N, and a reduction in coefficient of friction from 0.235 to minimum 0. 063. SEM analyses indicates that the wear scare obtained with fullerene copolymer exhibited mild scratches, while sharp grooving and serious pull-out phenomnon were observed in the presence of base stock without additive .The improvements in friction, wear and load-carrying capacity are probably due to the presence of fullerene copolymer nanoballs, which may act as molecule ball bearings, which in turn lead to elastic rolling lubrication.