Transverse Gauge Variation in Strip and Sheet Rolling

Abstract

Large forces acting on the working surfaces of rolls in a mill producing strip or sheet will deform these rolls and, in an endeavour to obtain products of uniform thickness, the roll surfaces are ground to a shape which would compensate for this deflection. Unsupported rolls deform by bending and local compression of the surface, and the latter results in edge thinning. Work rolls of backed-up mills, in addition, deform owing to the effect of the elastic support afforded by the backing roll. The mechanism of deflection is investigated and remedies suggested.

Variation of thickness across the strip and particularly its redistribution is shown to be responsible for a number of troubles such as locked-up stresses in the rolled strip, buckling and waviness of strip, edge cracking, lateral deflection of rolls, etc. The performance of a wide four-high mill can be much increased, particularly when rolling narrow strip, provided the secondary deflection of the work roll is controlled. This enables use of more slender rolls which, in turn, makes it possible to roll harder metals to smaller gauges.