Method and apparatus to control and adjust the drawing action in a rolling mill, and corresponding rolling mill

A rolling mill comprising:

• an apparatus to control and adjust a drawing action in a rolling mill (11) provided with a plurality of rolling stands (12a, 12b, 12c) located in sequence through which a product (13) being rolled passes in a direction of rolling (A), comprising:
• a video monitoring system (14) for acquiring a sequence of frames (15a, 15b, 15c) of the product (13) being rolled while the product (13) being rolled is positioned, during use, in at least one position along the rolling mill (11);
• a processing system (16), connected to the video monitoring system (14) and configured to:
• carry out processing of the sequence of frames (15a, 15b, 15c) and define in the sequence of frames (15a, 15b, 15c) at least one normal rolling range (17) wherein the product (13) being rolled has to be positioned within the at least one normal rolling range (17) in a situation of normal rolling;
• identify a position of the product (13) being rolled and a geometric characteristic of the product (13) being rolled;
• identify an oscillation of the product (13) being rolled as a function of a variation of the position of the product (13) being rolled over time with respect to the at least one normal rolling range (17) based on an analysis of the sequence of frames (15a, 15b, 15c);
• an automation system (18) associated with the rolling mill (11), connected to the processing system (16) and configured to determine an optimal condition of the drawing action for the product (13) being rolled corresponding to a condition of minimum oscillation of the product (13) being rolled in at least one inter-stand segment and to receive data relating to the position of the product (13) being rolled and of the variation of the position of the product (13) being rolled, so as to be able to determine a continuation of rolling if the product (13) is correctly positioned in the at least one normal rolling range (17), and to determine a variation of at least one rolling parameter if the position of the product (13) being rolled is outside of the at least one normal rolling range (17), in order to maintain or restore the optimal condition of the drawing action in the at least one inter-stand segment,
• wherein the automation system is configured to verify, as an initial step, under conditions of unknown drawing action, whether the product (13) being rolled passing between two consecutive rolling stands is vibrating or is not vibrating;
• and if the product (13) being rolled is not vibrating, to induce a vibration of the product being rolled between two consecutive rolling stands (12a, 12b, 12c), by increasing a speed (Vg1) of a rolling stand located upstream with respect to a speed (Vg2) of a rolling stand located downstream, wherein increasing the speed (Vg1) determines an increase in a flow rate and a creation of the vibration between the two consecutive rolling stands;
• wherein the automation system is configured to detect the oscillation of the product (13) being rolled with respect to the at least one normal rolling range (17) and to correct the at least one rolling parameter in the rolling stand located upstream to keep the product in a desired oscillation within the at least one normal rolling range (17);
• and
• wherein the product (13) is a long product.

A method to control and adjust a drawing action in a rolling mill (11) provided with a plurality of rolling stands (12a, 12b, 12c) located in sequence through which a product (13) being rolled passes in a direction of rolling (A), the method comprising:

• determining an optimal condition of the drawing action for the product (13) being rolled, corresponding to a condition of minimum oscillation of the product (13) being rolled in at least one inter-stand segment;
• acquiring a sequence of frames (15a, 15b, 15c) of the product (13) being rolled in at least one position along the rolling mill (11);
• processing the sequence of frames (15a, 15b, 15c), wherein the processing includes defining, in the sequence of frames (15a, 15b, 15c), at least one normal rolling range (17) wherein the product (13) being rolled has to be positioned in a situation of normal rolling;
• identifying a position of the product (13) being rolled and geometric characteristics of the product (13) being rolled;
• identifying an oscillation of the product (13) being rolled as a function of a variation of the position of the product (13) being rolled over time based on an analysis of the sequence of frames (15a, 15b, 15c) acquired;
• sending data relating to the position of the product (13) being rolled and the variation of the position of the product (13) being rolled to an automation system (18) associated with the rolling mill (11), so that the automation system (18) can determine a continuation of the rolling if the product (13) is correctly positioned within the at least one normal rolling range (17) or a variation of at least one rolling parameter if the position of the product (13) being rolled is outside of the at least one normal rolling range (17), in order to maintain or restore the optimal condition of the drawing action for the product (13) being rolled;
• verifying, as an initial step, under conditions of unknown drawing action, whether the product (13) being rolled that passes between two consecutive rolling stands is vibrating or is not vibrating;
• if the product (13) being rolled is not vibrating, at least one step of inducing a vibration on the product being rolled between two consecutive rolling stands (12a, 12b, 12c), by increasing a speed (Vg1) of a rolling stand located upstream with respect to a speed (Vg2) of a rolling stand located downstream, wherein increasing the speed (Vg1) determines an increase in a flow rate and a creation of a vibration between the two consecutive rolling stands;
• at least one step of detecting the oscillation of the product (13) being rolled with respect to the at least one normal rolling range (17) and correcting the at least one rolling parameter in the rolling stand located upstream in order to keep the product in a desired oscillation within the at least one normal rolling range (17).