Pressure distribution in a two-roll mill.

Abstract

An asymmetric pressure distribution in a pair of rolls rotating at equal and unequal speed for Newtonian fluid was obtained by lubrication model analysis and was compared with experimental values. The work was carried out with a pair of rolls of radius R = 8.2cin in the range of fluid viscosity μ = 1.5-15 Pa•s, half of minimum nip clearance h0 = 35-390μ/m, mean roll speed um = 0.26-1.56 m/s and roll speed ratio Nr = 0.5-7. The experimental pressure profiles and force separating rolls are well represented by the calculated values in the region of N''ca (= μuf(R/h0)2/γ)7, where γ is liquid surface tension. In the range of N''ca>2.5 × 107, the absolute values of the minimum pressure decrease with increasing N''ca. The theoretical pressure distribution can be well corrected by considering that the liquid film separating point predicted by the theory comes near to the minimum nip.