A comparison of friction coefficients in cold rolling

Abstract A sensor which uses strain gauges mounted on a conical cantilever sensing element, has been designed to measure the three forces of interest at the roll/strip interface, namely the normal force, the friction force in the rolling direction and the friction force in the direction transverse to rolling. Successful experiments have been conducted with the sensor using 1100 aluminium, with a low aspect ratio, as the rolled product. An analysis of the experimental results reveals a ‘rotating friction vector’ which is not parallel to either axis of symmetry. This vector can be found when the transverse friction force, which is orthogonal to the rolling direction, is added vectorially to the friction in the rolling direction. When the rotating friction vector is considered in terms of ‘Coulomb’ friction, μ, a constant, direction dependent μ occurs. The μ arrived at in this manner is compared to an ‘old’ model by Ford and is found to be in agreement for this specific rolling situation. Experimental results are presented for a 24.2% reduction.