Experimental Study of Roll Flattening in Cold Rolling Process

Precise control of the sheet thickness in cold rolling process is becoming more and more important. Sheet thickness after cold rolling, depends on the initial thickness, the initial roll gap as well as the elastic deformation of the rolling mill including rolls. As production amount of high-strength materials increases, the elastic deformation of rolls becomes larger and more important. In cold rolling of high-strength steel sheets, it is reported that the rolls show non-circular deformation and the rolling load predicted by Hitchcock's equation does not agree with experiments. In this study, stainless steel sheets were cold-rolled and the profiles of the partly rolled specimen were measured by a laser profilometer. Meanwhile, data processing method to reveal the sheet profiles in the roll bite is developed. Flattened radius R-P calculated from the measured profile is smaller than the radius RH estimated by Hitchcock's equation. In addition, the contact length L-M estimated with consideration of elastic deformation of the sheet is in good agreement with L-P measured by a laser profilometer under three lubrication conditions.