Research Of Cold Rolled Carbon-steel Strip Surface Roughness Genetic Law

More and more attentions are paid to the surface quality of cold rolling strip with the development of cold rolling technique. The surface roughness as a vital factor of surface quality not only affects succeeding stamping deformation performance and outer appearance of galvanized products, but also alters the corrosion resistance capability. The methods to control surface roughness and optimize surface roughness have become technical challenges for designers and practicing engineers in cold rolling process. Based on foreign and domestic relevant studies and literatures, the effects of work roll roughness, technological parameters and lubrication condition on the milled strip roughness are rigorously investigated in laboratory experiments. The main work in this thesis as follows.(1) Laboratory experiments reveal that strip surface roughness increased as the work rolls surface rougher.(2) Laboratory experiments reveal that an over thick lubricant film results in matters surface, while too thin film might allow work roll-strip contact explicitly, which may be primarily responsible for roll wear and sheet surface defects, there is an optimum presence of lubrication film.(3) Laboratory experiments reveal that reduction ratio affect strip surface roughness in cold rolling process. As the reduction ratio increase, the strip roughness rises in the beginning and the strip roughness decrease lately.(4) Laboratory experiments indicate that rolling speeds ascend, the lubrication film thickness increase followed, lead to rougher surface of rolled strip.(5) We study the surface topography though SEM. It reveal that as passes increase, the trace of roll appeared in strip surface become more slender. The low the surface roughness of roll is, the more slender the trace is. Because of the effect of the oil dragged overflowing, the press increases within lubrication oil film. Then the strip surface is squashed, lead to lots of pigs. Due to the too deep defect, after the final rolling, there are some micro-defects remain on strip surface.