The influence of surface waviness on hydrodynamic lubrication behavior in cold rolling process

Rolling lubrication is a hot topic in the field of tribology. In the process of rolling, surface roughness has long been concerned by researchers, for rolling lubrication is often defined by the distance between surface asperities. Since Patir and Cheng proposed the average flow theory of partial hydrodynamic lubrication for metal working process, many scholars have used this theory to establish more precise lubrication models considering surfaces roughness. But the features of rolling lubrication do not only depend on surface roughness, surface waviness of rolling sheet can also affect the hydrodynamic states. However, the related researches are actually rare to see. In this paper, partial lubrication formula for cold rolling based on average flow theory is set, both surface waviness and roughness are considered in the theoretical analysis. And the results will show what surface waviness and inlet velocity exert on rolling lubrication.