Determination of Oil Film Thickness in Rolling from the Relationship between Surface Roughness of Strip and Roll : Investigation into Friction and Lubrication in Cold Rolling

Abstract

Author proposes a method of determination of the oil film thickness from the contact behaviors between the rolls and the strip. The oil film thickness at the contact hcon is written as hcon = (the surface roughness of roll) × 1/2 + (the surface roughness of strip) × 1/2 The oil film thickness in rolling is measured by means of a similar method to that proposed by Saeki et al. The measured values are in good agreement with the calculated values. When the oil film thickness is greater than hcon, the reflection in the rolling direction R agrees with that in the transverse direction R90. When that is smaller than hcon, the reflection in the rolling direction is higher. Consequently, a parameter which can represent the lubrication mechanism in cold rolling is derived as α=R/R When α=1, the lubrication mechanism is hydrodynamic and when α > 1, that is boundary.