| 摘要 |
PURPOSE:To roll-form easily a differential thickness plate having a non-symmetrical shape in its thickness direction and to improve its productivity by controlling independently the drives of the upper and lower rolls of a mill. CONSTITUTION:In a state of both-rolls-driving rolling, a steel plate 12 having the thickness t1 is rolled by a little distance from the front end of a thin thickness part 2, which is set by a setter. Next, the driving state is changed into a counter-driving state by setting the ratio of the driving torque of an upper work roll 14a and the damping torque of a lower work roll 14b to the prescribed ratio. In this state, the plate 12 is rolled throughout the whole length of the thin thickness part 2. In this case, the part 2 is so formed that the thickness t4 to be deformed by the roll 14b is remarkably thin as compared with the thickness t3 to be deformed by the roll 14a. Next,when the driving torque of reverse direction is applied to the roll 14a by a program control, a differential thickness plate 1 having a thick part of thickness t1 and a thin part 2 of thickness t2 and a lower surface 3 formed into an approximately flat one is rolled out to the feeding side of the rolls 14a, 14b. |
