Factors Affecting Characteristics of Boundary Lubrication in Cold Rolling of Steel Sheets.

In order to clarify the mechanism of lubrication in boundary lubrication areas in cold rolling of steel sheets, the cold rolling experiments are made using stainless steel (SUS 430) sheets with various surface roughness at the entry of rolling, and in neat lubrication of two mineral oils with different viscosities. Also, the friction coefficient in boundary lubrication areas and the thickness of lubrication film due to mechanical capture are calculated with the numerical analysis model of cold rolling lubrication and the rolling experiment data. Then, the factors affecting them and their characteristics based on the factors are discussed. As a result, it has been found that the friction coefficient in boundary lubrication areas is affected by the pressure ratio pm/(σy0αy0) and that the thickness of lubrication film due to mechanical capture is influenced by the initial equivalent surface roughness.