Starvation Behavior in Cold Rolling of Aluminum with Oil-in-Water Emulsion

Abstract

Reich, et al. ( 1 ) reported that the rolling force for the cold rolling of aluminum increased when starvation occurred in the oil-in-water (O/W) emulsion used as the rolling fluid. They reported that the starvation occurrence was dependent on the emulsion concentration and the size of the oil droplets, but the thickness of a starved lubricant film was independent of the rolling speed. However, from their experimental results, the cause of the increase of the rolling force and the quantitative inlet oil film thickness at the entrance between the roll and the workpiece for the O/W emulsions cannot be understood. In this study, the aluminum rolling experiments using O/W emulsions with different concentrations were carried out in order to reproduce the increase of the rolling force. Experiments were carried out using a laboratory mill with two high rolls. The workpiece material was an aluminum A1050-H. Commercial rolling oil was used as base oil for the aluminum emulsion. The rolling force was measured during the rolling and the appearance of the workpiece after rolling was taken. Moreover, the effect of the surface roughness of the rolls on the increase of the rolling force was investigated. The increase of the rolling force was reproduced in the aluminum rolling with the O/W emulsion using the laboratory rolling mill. It was observed that the increase of the rolling force occurred after the oil starvation, and it depended on the oil starvation, the oil film thickness, the surface roughness of the roll, the rolling speed, and the reduction in thickness.