Rolling mill

A rolling mill of the type wherein a pair of upper and lower work rolls are rotated at such different peripheral velocities that the peripheral velocity ratio is substantially equal to an elongation ratio at which a sheet metal is rolled;

• which comprises
• (a) velocity detecting means for detecting the velocities of the sheet metal entering and leaving one or each rolling mill stand,
• (b) first work roll velocity control means for controlling the peripheral velocity of one of said pair of upper and lower work rolls which is rotated slower than the other,
• (c) second work roll velocity control means for controlling the peripheral velocity of the other work roll,
• (d) first velocity comparison means for comparing the peripheral velocity of said one work roll with the velocity of said sheet metal entering the or each rolling mill stand to generate tension correction signal representative of difference between the entering sheet metal velocity and the one work roll peripheral velocity when there exists a difference therebetween, and first sheet metal tension control means responsive to said tension correction signal for correcting the tension of the sheet metal entering the or each rolling mill stand, whereby the velocity of said sheet metal entering the or each rolling mill stand may be maintained substantially equal to the peripheral velocity of said one work roll,
• (e) second velocity compaison means for comparing the peripheral velocity of said the other work roll with the velocity of said sheet metal leaving the or each rolling mill stand to generate tension correction signal representative of difference between the leaving sheet metal velocity and the other work roll peripheral velocity when there exists a difference therebetween, and second sheet metal tension control means responsive to said second-mentioned tension correction signal for correcting the tension of the sheet metal leaving the or each rolling mill stand, whereby the velocity of said sheet metal leaving the or each rolling mill stand may be maintained substantially equal to the peripheral velocity of said the other work roll.