The influencing factors of roll gap shape

Since the plate with transverse thickness difference and flatness mainly depends on the actual roll gap shape when rolling, therefore, must study the factors that influence the actual roll gap shape designed and used to roll the original shape. Main factors influencing the roll gap shape of the elastic deformation of roll, roll the uneven heat expansion and roll wear and tear. Roll in the process of rolling roll of uneven heat expansion of heating and cooling condition along the roll distribution is uneven. In most cases, roll temperature higher than the edge of central ( But sometimes also can appear the opposite) And the general on the temperature below operation side of the drive side of temperature. In roller surface on the temperature of the roller core diameter direction is different also, in the stable rolling stage, the roller surface temperature is higher, but because when stop rolling roller surface cooling faster, also can appear the opposite situation. Roll between workpiece and work roll wear and friction between support roll and work roll can make uneven roll wear, affect the shape of the roll gap. But due to the factors affecting roll wear too much, so it is difficult to theoretically calculate the roll wear, can only rely on a large number of measurement of wear rules for all kinds of rolling mill, so as to take corresponding compensation to the roll wear. The elastic deformation of roll that is mainly including roll elastic bending and elastic flattening. Roll elastic flattening along the barrel length distribution is uneven, this is mainly due to uneven distribution of unit pressure. In addition, near the edge of rolled pieces have less squashed, appears in edge thinning area, with the decrease of the roll diameter, edge thinning area also decreases, and generally the area although is not very big, but also affect the yield. In between the working roller and support roller also have inhomogeneous elastic flattening, it directly affects the work roll bending deflection. Roll of elastic bending deflection is usually the main factors influencing the roll gap shape. For a long time, according to the analysis of roll bending, think when the support roller diameter ratio and diameter of work roll is larger, the bending force is mainly borne by the supporting roller, so the work roll deflection can approximate think equals the deflection of support roller. So that roll shape design can be used to support roll roll deflection difference instead of work roll roll deflection of the poor. But the most actually doing so is not correct. Theory and experiment show that when the rolling work rolls of the actual deflection is much bigger than the support roller. This is mainly because the work roller and support roller between elastic flattening deformation, resulting in the part of wide plate beyond the range of the work roll supported roll cantilever bending effect, thus greatly increased the deflection of work roll itself. The smaller the width of rolled piece, work roll deflection of the larger. As a result, the roll shape design, if does not consider the work roll elastic deformation characteristics, and with only a support roll roll deflection calculation to deal with the problem of poor, the results do not tally with the actual. I. e. the four high rolling mill work roll bending deflection depends not only on the bending deflection of the backup roll, and it also depends on the backup roll and work roll caused by the inhomogeneous elastic flattening between deflection.