Plate-out efficiency related to oil-in-water emulsions supply conditions on cold rolling strip

Abstract

Oil-in-water emulsions are generally used in tandem cold rolling mills as lubricants, as they provide good lubricity and cooling performance. Lubricants are supplied by either a recirculation system or a direct application system. The dynamic concentration and the plate-out are known as the two main lubrication mechanisms, respectively, used in the two conventional lubrication applications. But it is difficult to realize direct control of the lubrication characteristics only using the dynamic concentration mechanism while the plate-out mechanism makes it possible. Therefore, this article is concerned with an experimental study of the efficiency of plate-out oil film formation, focusing on emulsion spraying conditions. Emulsion supply conditions are also examined in the plate-out test, which enables extremely rapid evaluation in a time equivalent to that in actual high-speed cold rolling. An air atomizing nozzle, which supplies a mixture of emulsion and air, was more efficient for plate-out oil film formation than the conventional flat nozzle, which only supplies emulsion. Air atomizing expands the space of the emulsion droplet and may prevent outflow of the plate-out oil film. The results of this research suggest that it is important to consider emulsion supply conditions as well as emulsion make-up conditions.