Pinch roll device for rolled metallurgic products

Abstract

A pinch roll device ( 1 ) for rolled metallurgic products comprises:—a first pinch roll and a second pinch roll ( 2, 3 ), a passage gap ( 5 ) being defined therebetween, the first and second rolls ( 2, 3 ) being rotable about a first rotation axis and a second rotation axis (Y 1, Y 2 ), respectively, to draw a rolled metallurgic product ( 10 ) through the gap ( 5 ),—a hydraulic actuator ( 21, 41 ) comprising a hydraulic actuator ( 21, 42, 43 ) connected to the first roll ( 2 ) and/or the second roll ( 3 ) to reciprocally either approach or space apart the first and second rolls ( 2, 3 ), so as to either reduce or increase the width of the passage gap ( 5 ), respectively,—a pressure sensor ( 25 ) in the hydraulic circuit ( 20 ),—a position sensor ( 24 ) in the actuator ( 21 ),—a reversible pump ( 9 ) in the hydraulic circuit ( 20, 41 ) connected to the actuator ( 21, 42, 43 ) to slidingly move a piston ( 22 ) connected to the first roll ( 2 ) and/or to the second roll ( 3 ).

1 . (canceled) 
     
     
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         10 . (canceled) 
     
     
         11 . (canceled) 
     
     
         12 . A pinch roll device for rolled metallurgic products, comprising:
 as first pinch roll and as second pinch roll, between which a passage gap for a rolled metallurgic product is defined, said first and second rolls being rotatable about first and second rotation axes, respectively, to draw by friction said metallurgic product through said gap,   a hydraulic closed circuit acting on said first and second rolls to reciprocally either approach or space apart said first and second rolls so as to either reduce or increase the width of said passage gap, respectively, said hydraulic circuit comprising at least one hydraulic actuator connected to said first roll and/or to said second roll to either reciprocally approach or space apart said first and second rolls,   a pressure sensor in said hydraulic circuit to determine the force transmitted by said actuator to said first roll and/or to said second roll,   a position sensor in said actuator to determine the movement of said first roll and/or of said second roll,   a reversible pump in said hydraulic circuit, said pump being connected to as first chamber and a second chamber of said at least one hydraulic actuator to slidingly move a piston of said at least one hydraulic actuator, said piston being connected to said first roll and/or to said second roll, the rotation of said reversible pump in one direction or in the other allowing to send a fluid directly to either one or the other of said first and second chambers, respectively.   
     
     
         13 . A pinch roll device according to  claim 12 , wherein said first and second rolls are reciprocally interconnected by means of a mechanical and/or hydraulic connection. 
     
     
         14 . A pinch roll device according to  claim 13 , wherein said hydraulic circuit comprises a hydraulic actuator connected to said first roll and said connection comprises a geared transmission between said first and second rolls to connect said hydraulic actuator to said second roll, by means of said first roll. 
     
     
         15 . A pinch roll device according to  claim 13 , wherein said hydraulic circuit comprises a pair of hydraulic actuators connected to said first and second rolls, respectively, to move said first roll from and to said second roll while moving said second roll from and to said first roll, said connection comprising a compensation circuit between said first and second rolls. 
     
     
         16 . A pinch roll device according to  claim 14 , wherein said hydraulic circuit comprises a pair of hydraulic actuators connected to said first and second rolls, respectively, to move said first roll from and to said second roll while moving said second roll from and to said first roll, said connection comprising a compensation circuit between said first and second rolls. 
     
     
         17 . A pinch roll device according to  claim 14 , wherein said transmission comprises first and second lever arm, said first and second rolls being respectively restrained thereto, so as to rotate about respective rotation axes, said first and second arm being rotatable about a third rotation axis and a fourth rotation axis, respectively, to reciprocally either approach or space apart said first and second rolls, said gear comprising at least as first toothed sector and a second toothed sector, integral with said first and second arms, respectively, said first and second toothed sectors being meshed with each other to transmit the rotation between said first and second levers. 
     
     
         18 . A pinch roll device according to  claim 17 , wherein said first, second, third and fourth rotation axes are parallel to one another. 
     
     
         19 . A pinch roll device according to  claim 12 , wherein said pump is controlled by an electric motor controlled means of a control unit connected to said position sensor and to said pressure sensor, the position of said piston depending on the angular position of said motor, the speed of said piston depending on the angular speed of said pump. 
     
     
         20 . A method of operating a pinch roll device for rolled metallurgic products, said device comprising:
 a first pinch roll and a second pinch roll, between which a passage gap for a rolled metallurgic product is defined, said first and second rolls being rotatable about first and second rotation axes, respectively, to draw by friction said metallurgic product through said gap,   at least one hydraulic actuator connected to said first roll and second roll to reciprocally either approach or space apart said rolls so as to either reduce or increase the width of said passage gap, respectively,   a reversible pump connected to a first chamber and a second chamber of said at least one hydraulic actuator to slidingly move a piston of said at least one hydraulic actuator, said piston being connected to said first roll and/or to said second roll,   
       said method comprising:
 a step of checking either the presence or absence of said metallurgic product in said passage gap, 
 a step of checking the position of said first roll, implemented when the absence of said metallurgic product in said passage gap is identified in said checking step, 
 a step of checking the pressure of said hydraulic actuator, implemented when the presence of said metallurgic product in said passage gap is identified, said pressure checking step comprising a sub-step of refreshing said position reference value, said sub-step of refreshing said position reference value is operated when said measured pressure value is identified as equal to said pressure reference value in said pressure comparing, sub-step. 
 
     
     
         21 . An operation method according to  claim 20 , wherein said step of checking the position of said first roll comprises a position comparing sub-step to compare a measured position value, which may be associated with the position of said first roll, with a reference position value. 
     
     
         22 . An operation method according to  claim 20 , wherein said step of checking the pressure in said hydraulic actuator comprises a pressure comparing sub-step to compare a measured pressure value, which may be associated with said hydraulic actuator, with a reference pressure value. 
     
     
         23 . An operation method according to  claim 21 , wherein said step of checking the pressure in said hydraulic actuator comprises a pressure comparing sub-step to compare a measured pressure value, which may be associated with said hydraulic actuator, with a reference pressure value.