Rolling mill Roll pass Design about Spread and elongation

Spread and elongation

Speard :- when the steel ( section) compressed in the roll it is  move in free space in rolling passes  it called spread , in case plastic deformation apply here 

Here some formula for calculate spread 

Spread displayed by - ∆b

1- ∆b = (∆h × bin ×√( bin × Rn )) / (3 × ( bin^ + (  hin × hout))

2- ∆b = 0.66 × (∆h/ hin+hout) × √(∆h × Rn))

Where:- 

n   = new roll diameter

Rn= new roll radius

Elongation

Elongation is percentage of tension from section to point of failure

Formula of calculate elongation

Ain / Aout = Et

Where:- 

Ain =  Entry steel ( section) cross sectional area 

Aout = Exit steel( section ) cross sectional area 

Et  =  total elongation

Average elongation 

n√( Ain / Aout ) = Eave 

Where:- 

n = number of passes 

Ea = average elongation