METHOD FOR CONTROLLING SHEET THICKNESS IN HOT CONTINUOUS ROLLING MILL

PROBLEM TO BE SOLVED: To improve the precision of a sheet thickness in a hot rolling by using sheet velocity at the inlet side, sheet thickness at the inlet side and sheet velocity at the outlet side in a downstream side stand calculated from angle and angle velocity of a looper and sheet velocity at the outlet side in an upstream side stand, calculating the sheet thickness at the outlet side in the downstream side stand with a mass-flow constant rule and controlling to a target sheet thickness. SOLUTION: The inlet side sheet thickness in the downstream side stand 20i+1 , the outlet side sheet velocity in the upstream side stand 20i and the outlet side sheet velocity in the downstream side stand 20i+1 in a hot continuous rolling mill constituted of plural rolling stands 20i , 20i+1 providing roll velocity control devices 32i , 32i+1 and rolling reduction positional control devices 30i , 30i+1 , and the looper 22, are used to calculate the outlet side sheet thickness in the downstream side stand 20i+1 with the mass-flow constant rule. The outlet side sheet velocity in the upstream side stand 20i is corrected so that the outlet side sheet thickness in the downstream side stand becomes the target sheet thickness by using the looper angle θ and the looper angle velocity ω arranged between the upstream side and the downstream side stands 20i , 20i+1 , and the outlet side sheet thickness in the downstream side stand 20i+1 is calculated and then, the precision of the sheet thickness can be improved.