Question

A strip 300 mm wide and 25 mm thick is rolled to a final thickness of 21 mm with ∅500 mm rolls running at 60 RPM. K = 275 MPa and n=0.2. Using two passes of draft = 2 mm (i.e. t₁=23 mm and t₂=21 mm) , the class found that the rolling forces were 936 and 1220 kN respectively, and that the power requirement was 171 kW (based on the 2^nd pass). It is hypothesized that since the flow stress is higher for the 2^nd pass, the power requirement would be reduced by taking the first pass at the maximum draft of 2.5 mm (i.e., t₁=22.5 mm and t₂=21 mm). Compute the rolling forces and the power requirement for this modification of the process.   (Pass 1: F=1096 kN, t=13.7 x 10³ Nm per roll, P=86.1 kW per roll; Pass 2: F=1076 kN, t=10.4 x 10³ Nm per roll, P=65.5 kW per roll)

Answer 1