Question

In a rolling process, a sheet of 25 mm thickness is rolled to 20mm thickness. Roll is of 600 mmdiameter and it rotates at 100 rpm. The roll strip contact length will be

• A. 5 mm
• B. 39 mm
• C. 78 mm
• D. 120 mm

Answer 1

The correct option is B 39 mm

Given;

$t_i=25mm{t}_f=20mm$

R = 300 mm N = 100 rpm


Angle subtended by the deformation zone at the roll centre,

$cos\theta =1-\frac{\Delta h}{D}=1-\frac{5}{600}$

$\theta =0.129rad$

Roll strip contact length
$L=\theta .R=0.129\times 300$
$=38.7$ mm