Plant to control the section area of a rolled product and corresponding method

Abstract

A plant to control the section of a rolled product passing through a rolling train comprises at least two rolling stands, at least a section area measurer disposed immediately at exit from at least one of the stands located downstream of the first stand, a control unit comprising a database, in which at least the parameters relating to the expected value of the section of the rolled product at exit from each stand are memorized, means to compare the values detected by the section area measurer with the values memorized in the database and means to act on the rolling parameters according to said values detected.

1 . Plant to control the section area of a rolled product ( 12 ) passing through a rolling train ( 30 ) comprising at least two rolling stands ( 11   a ,  11   b ,  11   c ,  11   d ) equipped with rolling rolls ( 18 ), used in particular for products with a section from 70 mm and more, characterized in that it comprises:
 a section area measurer ( 10 ) disposed immediately at exit from at least one of the even stands (second, fourth, sixth, etc.) located downstream of the first stand ( 11   a ) and configured to measure the section area of a round profile;   a control unit ( 20 ) comprising a database ( 21 ), in which at least the parameters relating to the expected value of the round section of the rolled product ( 12 ) at exit from each stand are memorized, and comprising means to compare the values detected by the section area measurer ( 10 ) with the values memorized in said database ( 21 );   wherein, in the event of dissimilarity between the above-mentioned values, said control unit ( 20 ) comprises means to act on at least the motors ( 14 ) associated with said rolling rolls ( 18 ) in order to vary the rotation speed of said rolling rolls ( 18 ) so as to modify, either to increase or decrease, the drawing action or thrust between at least two of said stands ( 11   a ,  11   b ,  11   c ,  11   d ) so as to return the value of the section of the rolled product ( 12 ) to the expected value.   
     
     
         2 . Plant as in  claim 1 , characterized in that said control unit ( 20 ) comprises means to also act on adjustment means ( 15 ) of the calibration gap between said rolling rolls ( 18 ), said means being able to be activated when said modification of the drawing action or thrust between the stands is not able alone to bring the values measured of the section to the values expected. 
     
     
         3 . Plant as in  claim 1 , characterized in that said section area measurer ( 10 ) is disposed at exit from the last rolling stand ( 11 ) of said rolling train ( 30 ). 
     
     
         4 . Plant as in  claim 1 , characterized in that said section area measurer ( 10 ) is disposed at exit from one or more intermediate rolling stands ( 11 ) of said rolling train ( 30 ). 
     
     
         5 . Plant as in any claim hereinbefore, characterized in that a device ( 23 ) to control the characteristics of the rolled product ( 12 ) arriving at a rolling stand is associated with said control unit ( 20 ). 
     
     
         6 . Method to control the section of a rolled product ( 12 ) in a rolling train ( 30 ) comprising at least two rolling stands ( 11   a ,  11   b ) equipped with rolling rolls ( 18 ), used in particular for rolled products ( 12 ) with a diameter from 70 mm and more, characterized in that it comprises:
 a first step in which a section area measurer ( 10 ), disposed at exit from at least one of the even stands (second, fourth, sixth, etc.) located downstream of the first stand ( 11   a ), detects the size of the section area of the rolled product ( 12 ) exiting from the corresponding rolling pass;   a second step in which a control unit ( 20 ), comprising a database ( 21 ) in which at least the parameters relating to the value of the section area of the rolled product ( 12 ) at exit from each stand are memorized, compares the values detected by the section area measurer ( 10 ) with the values memorized in said database ( 21 );   a third step in which, in the event of dissimilarity between the above-mentioned values, said control unit ( 20 ) acts on at least the motors ( 14 ) associated with said rolling rolls ( 18 ) in order to vary the rotation speed of said rolling rolls ( 18 ) so as to modify, either to increase or decrease, the drawing action or thrust between at least two of said stands ( 11   a ,  11   b ) so as to return the value of the section to the expected value.   
     
     
         7 . Method as in  claim 6 , characterized in that, in the event that the dissimilarity between the expected value of the section area and the value measured is great, it provides a step in which the adjustment of the drawing action or thrust is partialized and distributed over all the stands of the rolling train. 
     
     
         8 . Method as in  claim 6  or  7 , characterized in that in the event that the dissimilarity between the expected value of the section area and the value measured is great, it provides to intervene in the adjustment of the gap of at least one of the rolling stands ( 11   a ,  11   b ,  11   c ,  11   d ), so as to return the value of the section area of the rolled product ( 12 ) to the expected value. 
     
     
         9 . Method as in  claim 6 , characterized in that it provides to define an acceptable maximum value of the drawing action or thrust in relation to a condition where the tail end of the rolled product ( 12 ) is released with respect to at least the first rolling stand ( 11   a ). 
     
     
         10 . Method as in any claim from  6  to  9 , characterized in that it provides that in said database ( 21 ) values of the section area of the rolled product ( 12 ) at exit from at least some of the rolling stands ( 11   a - 11   d ) are memorized, in relation to one or more of its temperature, speed or diameter. 
     
     
         11 . Method as in  claim 10 , characterized in that it provides to detect the values of one or more of its temperature, speed or diameter at the entrance of the rolled product ( 12 ) into the rolling line and to select inside said database ( 21 ) the comparison values to be used in the adjustment carried out along the rolling line.