A standard cold-rolling stand has a support frame, a pair of small-diameter working rolls rotatable about respective horizontal, parallel, and vertically spaced axes defining a workpiece nip, and a pair of large-diameter backup rolls rotatable about respective axes parallel to and vertically flanking the working-roll axes. Each backup roll bears vertically on the respective working roll and the rolls of each pair are counterrotated to draw an elongated workpiece of predetermined maximum width generally perpendicular to the plane or planes of the roll axes through the nip. The rolls are pressed vertically toward the nip to compress and deform the workpiece in the nip. Such an arrangement may further have outer backup rolls engaging the already described inner backup rolls.
It is also known to axially shift the working rolls in such an arrangement in order to intensify the rolling action by varying the nip length. Since the workpiece width is rarely less than half of the backup roll width, this can be done with working and backup rolls of virtually the same length. Such a procedure leads however to rapid wear of the working rolls. Accordingly it is standard practice to schedule the various runs that are to be done so as to start with a run of medium width measured parallel to the roll axes and perpendicular to the strip travel direction and then to roll strips of increasingly greater width to the maximum width the stand can roll, then decrease the strip width gradually to a width substantially smaller than the starting width. Such a procedure rapidly heats up the rolls and then effectively pulls the workpiece back from the worn ends of these rolls, as it is the workpiece edges that subject the rolls to their principal material-removing wear.
With such an arrangement the central region of the working rolls remains relatively unused. Thus when the rolls must be returned to perfect cylindrical shape, which is normally done by grinding or otherwise machining them down, this unworn central part must be cut back, even though it is virtually unworn, to redress the roll. In systems with axially shiftable working rolls, such wear concentrated even in the end regions is very pronounced. Thus such a prior-art roll stand is often down for work in the rolls, this working being aggravated by having to cut down an unworn roll part.
It has been suggested to oscillate the working rolls axially slightly during a run to spread out the workpiece-edge wear. Although this does somewhat lessen the wear in any one spot, it still leaves all the wear at the roll ends.