Patent Publication Number: US-10328471-B2

Title: Edger feed rolls

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a 35 U.S.C. §§ 371 national phase conversion of PCT/EP2014/063489, filed Jun. 26, 2014, which claims priority of Great Britain Patent Application No. 1312262.7, filed Jul. 9, 2013, the contents of which are incorporated by reference herein. The PCT International Application was published in the English language. 
     TECHNICAL FIELD 
     This invention relates to a rolling mill edger, in particular for plate and Steckel mills. 
     TECHNICAL BACKGROUND 
     There is a trend in current plate and Steckel mills for the rolling of shorter feed stock such as short (usually thick) slabs or ingots. Typically, feed stock has been of the order of 3 to 4 meters or longer in length, but now there is a requirement to roll feed stock that is only of the order of 2 to 3 meters or less in length. This is particularly applicable in the case of plate mills rolling products from thick slabs or ingots and Steckel mills rolling ‘exotic’ materials e.g. titanium and nickel grades. These short slabs or ingots pose a particular problem with the operation of the edger. 
     Rolling mill edgers are used to maintain a required width of the slab as it is processed. The edgers typically comprise work rolls mounted at either side of a centerline on a section of a path over which the feed stock is moved in its various forms, for convenience referred to as a slab, but encompassing other forms from feedstock to finished product. The work roll separation is adjustable according to the plate width required. Idler rolls extend across the center part of the path, mounted with their roll axis perpendicular to and in the same plane as the centerline. Feed rolls are provided across a substantial part of the full width of the path ahead of or beyond the edger section of the path and these feed rolls are typically driven directly from motors via drive shafts, or sometimes using a gearbox. However, in the edger section of the path, between the edger work rolls, there are usually only idler rolls. This is not a problem if the slabs are of a conventional length as at least a part of the slab is always resting on driven rolls in the path outside the edger section. However, for short slabs, there may be a time in the rolling cycle when no part of the slab is on a driven roller and the slabs get stuck. Replacing the idler rollers with driven rollers in the section between the edger work rolls has the disadvantage that edger work roll changes are made more complicated because of the need to remove the driven rollers in that section to allow access for a roll change. Unlike the existing idler rollers, driven rollers cannot be simply lifted out, but would have to be disconnected from their gear and drive mechanism. JPS5671503 describes rolling equipment which can roll both plate and hot coil by providing an intermediate roller table which is raised into position for plate rolling. JPS6138706 describes an edging mill provided with a pair of non-driven edging rolls which are movable in the sheet width direction, to reduce the cost and space requirements associated with driven rolls. 
     SUMMARY OF THE INVENTION 
     In accordance with a first aspect of the present invention, a rolling mill edger comprises a pair of work rolls and a feed roll assembly; wherein the feed roll assembly comprises one or more driven feed rolls and drive means; wherein the feed roll assembly is mounted on a moveable mount such that the feed roll assembly is movable between an operative rolling position in the edger and a roll change position in the edger; and wherein the moveable mount comprises a pivot. 
     The driven feed rolls and their drive means are moved out of their operative position to allow a roll change to take place in the space that they occupy in normal rolling operation. Typically, the moveable mount rotates or pivots. Preferably, the pivot comprises an input shaft of the gearbox, belt drive or chain drive. 
     Preferably, the drive means comprises a motor and one of a gearbox, a belt drive or a chain drive. 
     Preferably, the edger comprises two feed roll assemblies and moveable mounts. 
     A feed roll assembly on a moveable mount is provided on each side, in the direction of travel of the plate, of the gap in which the edger work rolls are able to move. 
     Preferably, the edger further comprises one or more two part split driven feed rolls and the one or more driven feed rolls of the feed roll assembly are mounted between the two parts of one split driven feed roll. 
     Preferably, the edger further comprises a common support to support the two parts of the split driven feed rolls and the drive means. 
     In one embodiment, the drive means comprises a motor and a gearbox and the edger further comprises one or more two part split driven feed rolls and the one or more driven feed rolls of the feed roll assembly are mounted between the two parts of one split driven feed roll; and wherein the input shaft of the gearbox is coupled to one part of the split driven feed roll and adapted to be driven by the one part of the split driven feed roll. 
     Preferably, the other part of the split driven feed roll is coupled to the input shaft of the gearbox and adapted to be driven by the input shaft of the gearbox. 
     In accordance with a second aspect of the present invention, a method of carrying out edger work roll change in a rolling mill edger according to the first aspect comprises pivoting the driven feed rolls away from an operative rolling position and moving a first work roll into the location vacated by the driven feed rolls of the feed roll assembly; lifting the first work roll out of the edger; lifting a second work roll into the edger to replace the first work roll; moving the second work roll away from the operative rolling position of the driven feed rolls of the feed roll assembly; and pivoting the driven feed rolls of the feed roll assembly back into their operative rolling position. Preferably, the driven feed rolls are pivoted about a shaft of a feed roll drive mechanism. 
     If the first work roll is removed and renovated, it may be returned to the edger as the second work roll, after a period of time has elapsed, but preferably, the second work roll is different from the first work roll. 
     Preferably, the input shaft of the gearbox is driven by one part of the split driven feed roll. Preferably, the other part of the split driven feed roll is driven via the input shaft of the gearbox. 
    
    
     
       BRIEF DESCRIPTION OF THE INVENTION 
       An example of a rolling mill edger according to the present invention will now be described with reference to the accompanying drawings in which: 
         FIG. 1  illustrates a conventional edger with the edger positioned for a wide slab; 
         FIG. 2  illustrates a conventional edger with the edger positioned for a narrow slab; 
         FIG. 3 a    shows the problems faced in a conventional edger processing a short slab, seen from the side; 
         FIG. 3 b    shows the problems faced in a conventional edger processing a short slab, seen from above; 
         FIG. 4  illustrates extraction of a work roll from a conventional edger, during work roll change; 
         FIG. 5 a    illustrates a detailed construction of an edger according to the present invention, seen from above, showing the central rollers in their operative position; 
         FIG. 5 b    illustrates a detailed construction of an edger according to the present invention, seen from above, showing the central rollers in their idle position; 
         5   c  shows the operative position from the side; 
         5   d  shows the roll change position from the side. 
         5   e  shows the roll change position with the roll chock moved in between the rolls. 
         5   f  illustrates the roll change position, illustrating slide stops; 
         5   g  shows another view of an example of an edger according to the present invention, seen from above, showing the central rollers in the operative position; and, 
         FIG. 6  is a flow diagram of a method of carrying out roll change in a rolling mill comprising an edger according to the present invention. 
     
    
    
     DESCRIPTION OF PRIOR ART 
     In a plate mill or Steckel mill edger, for example as illustrated in  FIGS. 1 and 2 , edger work rolls  1 ,  2  are mounted in chocks  3 ,  4  which can be moved within a housing  5  by screws  6  and cylinders  7 . The edger work rolls  1 ,  2  are driven by electric motors  8  via respective gearboxes  9  and driveshafts  10 . Altering the separation of the edger work rolls  1 ,  2  about a centerline  11  of the edger, by moving the chocks  3 ,  4 , allows the edger to be adapted to the width of slab to be rolled. In  FIG. 1 , a wide slab  19   a  is shown. In  FIG. 2 , a narrow slab  19   b  is shown. As shown in  FIGS. 3A and 3B , driven feed rolls  12 ,  13 ,  14 ,  15  are used to support the slab, but because the edger work rolls  1 ,  2  move as illustrated by the arrows  16 , these feed rollers have to be mounted at a distance from a centerline  17  of the edger work roll, so as not to obstruct the movement of the edger work rolls. The centerline  17  is perpendicular to the direction of travel  20  of the slab. Typically, the pitch between the two innermost driven feed rolls  13 ,  14  is approximately 2000 mm, i.e. 1000 mm either side of the edger work roll centerline  17 . In between the innermost driven feed rollers there are usually only idler rolls  18  (i.e. un-driven rolls). The reason that these idler rolls  18  are not driven is that there is very little space available for a drive mechanism. As can be seen in  FIG. 2 , when the edger is edging narrow slabs  19  there is only a very small gap between the edger roll assemblies  1 , 2 , 3 , 4  and the idler rolls  18  and there is not enough space to install driveshafts for these idler rolls. 
     The fact that these idler rolls  18  are not driven causes problems with the transport of short slabs  19  or ingots through the edger because the slab or ingot can get stuck in a position where it is not being driven by any of the driven feedrollers. This is illustrated in more detail in  FIGS. 3 a  and 3 b   . A short slab  19  moving in a direction of travel shown by the arrow  20  loses contact with the driven feed rolls  12 ,  13  before it comes into contact with the driven feed rolls  14 ,  15 . This problem is particularly pronounced if no edging is being done on the slab, or ingot so that the edger rolls  1 ,  2  are not in contact with the slab  19  or ingot. In this situation, the slab or ingot only makes it through the edger if it has sufficient momentum to keep it moving. There might be some assistance from the edges of the slab resting on the top of the flanges of the edger work rolls but, particularly in the case of ingots which are usually tapered, this contact may be minimal or not present at all. There may also be small idler rolls mounted on the front face of the bottom edger roll chock. These provide some support for the slab or ingot, but they are not usually driven. Whilst in principal it would be possible to drive these support rollers it is not very practical due to limited space available. 
     To overcome this problem, some edgers use short, driven feed rollers which are gear driven from the center of the innermost full width feed roller. The innermost driven feed roller is divided into two parts and in between the two parts there is a gearbox which drives the small feed rollers which are located between the edger work rolls. Either a single pair of short feed rolls are driven via the gearbox, or two or more short feed rolls are driven from each side, via a train of gears. Although, this design addresses the problem of transporting short slabs through the edger, it introduces another problem. 
     The edger work rolls need to be changed at regular intervals due to wear. The most common method of changing the roll assemblies is to lift them vertically out of the edger housing as shown in  FIG. 4 . It is convenient in many large plate mill edgers to lift them with a hook  21  on the centerline  11  of the edger. One reason for this is that the gearboxes  9  and motors  8  and driveshafts  10  interfere with lifting the edger roll assemblies at other positions. Another reason is that because the central position is a non-working position it is easy to arrange for the edger roll assembly to disengage from the guides, typically slide stops  22 , which retain the edger roll assembly in the edger roll housing  5  during normal operation when the edger roll assembly is in a non-central position, as illustrated in  FIG. 5F  and allow it to be slid out in the central position as illustrated in  FIG. 5 e   , so this simplifies the roll change. Consequently many edgers move the work roll assembly into this central position for roll change as illustrated in  FIG. 4 . 
     In order to allow the edger roll assembly to move to this central position the idler rolls  18  which are illustrated in  FIGS. 1, 2 and 3  have to be lifted out first. In the case of simple non-driven idler rolls this is straightforward because the group of idler rolls is mounted on a common base which can be simply lifted out by an attachment on the same lifting hook  21  which is then used to remove the edger rolls  1 ,  2 . 
     However, in the case of the gear driven short feed rollers referred to above, this is not possible. The gearboxes and short feed-rollers cannot simply be lifted out for the edger roll change. Consequently, the edger roll change is made more complex because the guides  22  which retain the edger roll assemblies in the edger roll housing  5  have to be unbolted in order to take out the edger rolls  1 ,  2  in a non-central position. 
     Thus, the current options are to use an edger with idler rolls, which is better for the edger roll change, but is not very good at transporting short slabs or ingots through the edger, or to use an edger with gear driven short feed rollers, which is better at transporting short slabs or ingots, but makes the roll change more complex. 
     DESCRIPTION OF AN EMBODIMENT OF THE INVENTION 
     The present invention addresses the roll change problem associated with the gear driven type short feed rollers. 
     Instead of the fixed gearbox and short driven rollers used to ensure that a short slab is not stuck on idler rolls, the invention provides an assembly with driven rollers which is moveable between an operative, rolling position and a roll change position. The drive mechanism for the driven rollers may be via a gearbox, a chain drive, or a belt drive. A gearbox is preferred due to high loads, so the examples will be described with reference to a gearbox. However, they should be read as being equally applicable to the case of a chain or belt drive or other similar drive mechanism. 
     As illustrated by the embodiment of  FIGS. 5A and 5C , this can be achieved by using short driven feed rollers  23 , one or more feed rollers, or one or more pairs of such feed rollers, attached to and driven by a drive mechanism, in this example via a gearbox  24 , which can rotate about its input shaft  25 , so that the gearbox and short rollers can move between a working position  54  ( FIG. 5C ) where the short feed rollers fit between the edger rolls  1 , 2  and can be used to transport slabs through the edger as illustrated in  FIGS. 5A and 5C  and a roll change position  55  ( FIG. 5D ) in which the gearbox and the short feed rolls are rotated out of the space between the edger roll assemblies as illustrated in  FIG. 5D  so that the edger roll assemblies can be moved into this space for roll change as illustrated in  FIGS. 5B and 5E . A single rotating gearbox may be connected to all of the one or more feed rollers, or one or more pairs of feed rollers, or a rotating gearbox may be provided on each side of the edger, connected to the feed rollers on that side. One or more non-driven idler rollers  53  may be used in addition to the short driven feed rollers  23  as illustrated in  FIG. 5C . 
     The moveable assembly comprising the gearbox  24  and short driven feed rollers  23  may be completely separate from the feed rollers  13  and  14 , for example the gearbox may be mounted underneath the full width feed roller and have a separate drive shaft to the input shaft  25 . Due to the limited space available though, it is preferable to drive the input shaft  25  of the gearbox  24  from a half feed roller  13   a  as illustrated in  FIG. 5G . A respective motor  45  drives each drive shaft  46  to in turn drive a respective half feed roller  13   a . The input shaft  25  passes right through the gearbox  24  and drives another half feed roller  13   b . Bearings  26  and bearing supports  27  which support inner ends  28  of the half feed rollers  13   a  and  13   b  and the gearbox are separate from the gearbox  24  itself. In the conventional design with short driven rollers, the gearbox itself supports the inner ends of the half feed rollers because the gearbox is fixed. The cantilevered end  28  of the gearbox  24  is supported on a stop  29  in the normal operation position shown in  FIG. 5C . This stop may be adjustable or the stop may simply be shimmed during installation to set the short feed roller  23  at the correct height. The cantilevered end  28  of the gearbox  24  is prevented from moving upwards during normal operation by a simple pin or similar mechanism (not shown). Alternatively, a remotely operated latch, either mechanical or hydraulic, may be used. However, given the environment in this area and the relatively infrequent edger roll changes, a simple pin or similar system is sufficient. 
     For the edger roll change, the cantilevered gearboxes  24  are moved into the roll change position as illustrated in  FIGS. 5B and 5D . The pin or other mechanism which prevents the gearboxes from moving upwards is withdrawn and the gearboxes are lifted and pulled into the roll change position  50  by an attachment on the same crane attachment  21  which is used for the edger roll change. There is a stop (not shown) for the roll change position of the gearbox to prevent the short feed rolls  23  from making direct contact with the full width feed rolls  12 ,  15 . The system may include hydraulic cylinders or alternative mechanisms to move the gearbox from the normal operation position to the roll change position, if desired, but this is not essential as edger roll changes take place relatively infrequently. Replacement of the gearboxes after the edger roll change has been completed is done by simply reversing the sequence. 
       FIG. 6  shows the steps of the typical roll change process. When it has been determined that an edger work roll requires changing, rolling ceases  30 . Any retainer that holds the assembly comprising the drive mechanism and feed rolls in place is withdrawn  31  to allow the drive and feed roll assembly to move. The assembly is attached  32  to the lifting device and movement out of the central area of the edger into the roll change position is initiated  33 . Typically, this means that the lifting device pivots the assembly about the gearbox input shaft. At step  34  the drive shaft  10  is detached from the edger work roll as illustrated in  FIG. 4 . At step  35  the edger work roll assembly to be replaced is moved into the central area by cylinder  52  and detached from the cylinder  52 . The cylinder  52  is then moved back out of the way to allow the lifting device to be attached  36  and the work roll assembly is lifted out of the edger. The new work roll is lifted  37  into the central area of the edger using the lifting device, detached from this device and the cylinder  52  is moved into position and attached  38  to the work roll assembly. The work roll assembly is then moved  39  out of the central area and the driveshaft is re-attached  40 . The lifting device pivots  41  the drive and feed roll assembly back into position in the central area. Any retainers for the drive and feed roll assembly are replaced  42  and rolling can resume  43 . 
     Thus, the edger of the present invention is able to combine driven short feed rolls to make transporting of short slabs and ingots through the edger much easier with a clear central position for edger roll change. Rotation, or pivoting, of the gearbox and short feed roller assemblies about the gear input shaft moves the gearbox and short feed roller assemblies out of the window for roll change and thus allows the edger rolls to be changed in a central position which is much simpler than changing the edger rolls in a non-central position. There is no need to detach the gearbox and feed rolls at any stage in the process. 
     Latching and movement between the normal operation position of the drive mechanism and feed rolls and the roll change position may be carried out manually, or may be automated and operate under control of a controller (not shown).