Development Of Film Thickness And Experiments Study On Lubrication In Cold Rolling

Lubrication in cold rolling process is used not only to control friction, but also to control surface quality and thermal chamber. Successful cold rolling of strip at high speeds requires an optimum presence of lubricant film thickness at the contact. An over thick lubricant film may result in mattes surface, while too thin film might allow metal-metal contact, which may be responsible for roll wear and sheet surface defects. In order to have a better control on rolling process the awareness for the prediction and maintenance of desired minimum film thickness in the inlet zoon as a function of process variables such as roll speed reduction ratio, material parameter, and slip are essential. The factors that affect the minimum film thickness have been done and a mathematical model has been developed for the calculation of minimum film thickness use Matlab. What is more, the calculation model has been proved practically in the experiment. The main work in this thesis as follows.(1) On the relevant research about minimum film thickness, a new minimum film thickness was developed. Compared with other film thickness formula, the priority is that the influence of temperature was taken into consideration accurately and it can be used at high speed cold rolling, the speed could be more than 20m/s.(2) A calculation program under "Matlab", named as "minimum film thickness" was developed. Compared the theoretical results with the data got from experiments and relevant researches, proved that the minimum film thickness were accurate.(3) The cold rolling lubrication experiments in lab were done, and developed the relationship between friction coefficient and minimum film thickness and believed that each factor affect the friction coefficient through minimum film thickness. This model can improve the prediction accuracy of rolling force.(4) Use the minimum film thickness and the data got from the lab experiments analysis the factors that affect the cold rolling lubrication, pave the theoretically way for the mechanism research of lubrication and developing new lubrication oil.(5) The trends of roughness were analyzed in cold rolling process, which can be useful for the prediction of strip final roughness.