Combined operating modes and frame types in tandem cold rolling mills

Abstract

The invention relates to a method for combining the operating modes of individual rolling frames in a tandem cold rolling mill comprising respective pairs of working rolls ( 10 ) and back-up rolls ( 12 ) in 4-roll frames and in addition a pair of intermediate rolls ( 11 ) in 6-roll frames, at least the working rolls ( 10 ) and the intermediate rolls ( 11 ) interacting with devices for axial displacement. Said method is characterised by a combination of the following technologies: use of CVC/CVC plus technology with CVC roll contours of a higher order, where each working/intermediate roll ( 10, 11 ) comprises a roll surface that is extended by the amount of the travel displacement; use of P air C ross (PC) technology, whereby each working/intermediate roll ( 10, 11 ) can be pivoted parallel to the strip plane; use of strip-edge oriented displacement of the working/intermediate rolls ( 10, 11 ), each of the latter ( 10, 11 ) having a roll surface that is extended by the amount of the travel displacement, with a cylindrical or spherical section and said rolls being displaced symmetrically against one another relative t o the neutral displacement position (S ZW =0 and S AW =0 ) in the centre of the frame (Y-Y) by an identical amount in the direction of their rotational axes (X-X). The method is also characterised in that the CVC/CVC Plus technology, the strip-edge oriented displacement technology and optionally the PC technology can be achieved using a suitable plant concept with a single geometrically identical set of rolls.

1 . Method for the operation of the rolling stands of a tandem cold rolling mill, comprising a pair of work rolls ( 10 ) and a pair of backup rolls ( 12 ) in the case of four-high rolling stands and, in addition, a pair of intermediate rolls ( 11 ) in the case of six-high rolling stands, wherein at least the work rolls ( 10 ) and the intermediate rolls ( 11 ) interact with axial shifting devices, comprising the combined use of the following technologies within the multiple-stand tandem cold rolling mill: 
 use of CVC/CVC plus  technology with CVC roll contours of higher order, wherein each work roll/intermediate roll ( 10 ,  11 ) has a barrel lengthened by the amount of the shifting stroke;    use of  p air- c ross (PC) technology, wherein each work roll/intermediate roll ( 10 ,  11 ) can be swiveled parallel to the plane of the strip;    use of strip edge-oriented shifting of the work rolls/intermediate rolls ( 10 ,  11 ), wherein each work roll/intermediate roll ( 10 ,  11 ) has a barrel which is lengthened by the amount of the shifting stroke and which has a cylindrical or cambered cross section, and the work rolls/intermediate rolls ( 10 ,  11 ) are each symmetrically shifted from the the neutral shift position (S ZW =0 or S AW =0) by the same amount symmetrically to the center of the stand (Y-Y) in the direction of their axes of rotation (X-X).    
     
     
         2 . Method in accordance with  claim 1 , wherein, to use strip edge-oriented shifting, the work rolls/intermediate rolls ( 10 ,  11 ) are provided with a one-sided setback (d), such that when each work roll/intermediate roll ( 10 ,  11 ) is shifted, the beginning (d 0 ) of the setback (d) is positioned outside the strip edge, at the strip edge, or inside the strip edge, i.e., within the width of the strip ( 14 ).  
     
     
         3 . Method in accordance with  claim 1 , wherein the shift position of the work roll/intermediate roll ( 10 ,  11 ) in different strip width ranges is predetermined by piecewise-linear step functions which are based on different positions of the beginning (d 0 ) of the setback (d) relative to the edge of the strip ( 14 ).  
     
     
         4 . Method in accordance with  claim 1 , wherein optimum utilization of the combination of technologies within the multiple-stand tandem cold rolling mill is realized by optimized shifting strategies as a function of the strip width.  
     
     
         5 . Tandem cold rolling mill, comprising four-high/six-high rolling mills, each with a pair of work rolls ( 10 ) and a pair of backup rolls ( 12 ) in the case of four-high rolling stands and, in addition, a pair of intermediate rolls ( 11 ) in the case of six-high rolling stands, wherein at least the work rolls ( 10 ) and the intermediate rolls ( 11 ) interact with axial shifting devices, wherein the work rolls/intermediate rolls ( 10 ,  11 ) of the rolling stands each have a symmetrical barrel which is lengthened by the amount of the shifting stroke, has a cylindrical or cambered cross section, and is symmetrically positioned in the center of the stand (Y-Y) for the neutral shift position (S ZW =0 or S AW =0).  
     
     
         6 . Tandem cold rolling mill in accordance with  claim 5 , wherein the barrel of the work rolls/intermediate rolls ( 10 ,  11 ) is furnished with a one-sided setback (d), whose length ( 1 ) is divided into two adjacent regions (a) and (b), such that the first region (a), beginning with the radius (R 0 ), obeys the equation of the circle 
         ( l−X ) 2   +y   2   =R   2 , and the region (b) runs linearly, from which the following setback (d) or the following diameter reduction ( 2   d ) is obtained for these regions:    Region a:     =( R   2 −( R−d ) 2 ) 1/2     d=d ( x ) =R −( R   2 −( l−x ) 2 ) 1/2     Region b:       =l−a     d=d ( x )=constant.   
     
     
         7 . Tandem cold rolling mill in accordance with  claim 5 , wherein the transition of the setback (d) between the regions (a) and (b) is made with a sequential setback of the dimension (d) resulting from roll flattening according to a predetermined table.  
     
     
         8 . Tandem cold rolling mill in accordance with  claim 5 , wherein suitable choice of the rolling stands allows a combination of the different technologies of 
 strip edge-oriented shifting of the work rolls/intermediate rolls ( 10 ,  11 ).    CVC technology, and    swiveling of the work rolls ( 10 ), PC ( p air  c ross) technology within the multiple-stand tandem cold rolling mill.    
     
     
         9 . Method in accordance with  claim 8 , wherein the CVC/CVC plus  technology, the technology of strip edge-oriented shifting, and possibly PC technology are realized with only one geometrically identical set of rolls by means of suitable plant conception.