Patent Publication Number: US-7905443-B2

Title: Adjustable vertical accumulator for slitting operation

Description:
BACKGROUND OF THE INVENTION 
     The present invention is directed toward apparatus for handling coils of sheet metal strip which includes apparatus for unwinding a coil of single metal strip for slitting to form a plurality of separate strips of predetermined width for rewinding the strips into individual coils and, more particularly, toward a vertical accumulator that maintains continuous tension in each strip during the rewinding operation. 
     In the continuous production of rolling of metal strip, it is difficult to prevent the forming rolls of a rolling mill from bowing by a slight amount. This is particularly true with wider strips which is caused, in part by the weight of the forming rolls, but primarily by the enormous radial loading on the rolls as they progressively compress the metal strip to reduce its thickness. As a result, the metal strip which is formed usually varies in cross-sectional thickness with the center portion of the strip being a few thousandths of an inch thicker than the edge portions. Furthermore, as the strips increase in width, usually the differential in thickness across each strip also increases. Thus when the single strip is coiled, the center portion of the single strip has a tendency to increase in diameter at a faster rate than the edge portions which results in producing greater tension in the center portion of the strip within the coil. 
     When the original single coiled strip is subsequently run through a slitting operation to form a plurality of separate metal strips, it has been found that the stresses within the original strip are relieved, and in addition, the strips formed from the center portion of the single strip will have a slightly greater thickness than those strips formed from the edge portion. Thus when each of these separate strips is rewound on a common mandrel into separate coils, the tension in the strips forming the center coils of the mandrel is substantially greater than the tension in the strips forming the outer or end coils. 
     As is well known in the art, is desirable to maintain sufficient tension in each of the strips forming the separate coils during the rewinding operation so that the coils are not loosely formed and will not collapse or telescope after they are removed from the rewinding mandrel. Thus a common procedure is to provide a frictional resistance or drag on each of the separate strips between the slitting and rewinding operations. This drag develops a progressively increasing slack in the strips formed from the edge portions of the original single strip. To accommodate the slack, it is common to form a large deep pit in line between the slitting and rewind operation in which to suspended loops of the strips as the slack progressively increases. The pit essentially acts as an accumulator for the suspended loops between the slitting and rewinding operations. 
     In view of the trend toward larger coil diameters for obtaining more efficient handling of the strips and more efficient use of the machines which subsequently receive the metal strips, it has been found necessary to construct deeper and deeper pits. Pits may be as deep as twenty or thirty feet or more. Since the coils being unwound, slit and rewound and the equipment for performing these operations are extremely heavy, the entire operation is normally performed on the ground floor of a facility and on a solid concrete slab. Thus, when a pit is needed, it must be dug down through the concrete and into the earth below. The pit itself must then be finished with a concrete floor and walls and the like to prevent ground water or the like from seeping in. Depending on the terrain, it may or may not be possible to dig and properly finish the necessary pit. But even when it can be done, it is obviously an expensive process. Furthermore, once the pit is formed, its depth cannot be changed without going through additional substantial expense. 
     Therefore, a need exists for a less expensive accumulator that does not require the construction of a large pit between the slitting and rewinding operations and which can be used in substantially any facility. 
     SUMMARY OF THE INVENTION 
     The present invention is designed to overcome the deficiencies of the prior art discussed above. It is an object of the present invention to provide an accumulator in a slitting and rewinding operation that eliminates the need for a pit yet maintains proper tension on each of the individual slit coils. 
     It is another object of the present invention to provide an accumulator in a slitting and rewinding operation that can be used in almost every facility without the need for major renovations to the facility. 
     It is a still further object of the present invention to provide an accumulator in a slitting and rewinding operation which allows for the amount of accumulation to be adjusted. 
     In accordance with the illustrative embodiments demonstrating features and advantages of the present invention, there is provided a vertical accumulator for use in a sheet metal unwinding, slitting and rewinding operation. The accumulator accumulates the slack created in the plurality of strips cut from an initial wide coil so that the proper tension can be maintained on the individual strips being rewound. The accumulator includes an elongated mandrel that is mounted for rotation about a horizontal axis parallel to the axis of the original sheet metal coil and is arranged such that all of the plurality of cut strips pass over the top of the mandrel. The mandrel is located above the height of the coil and above the height of the slitter and the rewound individual strips. A plurality of disks mounted on the mandrel separate the cut strips from each other. Upwardly extending threaded rotatable rods located on either side of the sheet metal strips carry holders that releasably support the mandrel. Rotation of the rods causes the holders to move up or down to thereby adjust the height of the mandrel. 
     Other objects, features, and advantages of the invention will be readily apparent from the following detailed description of the preferred embodiments thereof taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For the purpose of illustrating the invention, there are shown in the accompanying drawings, one form that is presently preferred; it being understood that the invention is not intended to be limited to the precise arrangements and instrumentalities shown. 
         FIG. 1  is a diagrammatic representational view of a prior art system over which the present invention is an improvement; 
         FIG. 2  is a diagrammatic representational view similar to  FIG. 1  but showing the improvement of the present invention, and 
         FIG. 3  is a diagrammatic representation, shown partially exploded, of the adjustable vertical accumulator of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings in detail wherein like reference numerals have been used throughout the various figures to designate like elements, there is shown diagrammatically in  FIG. 1  a prior art system upon which the present invention is based. As is well known in the art, a sheet metal unwinding, slitting and rewinding operation starts with a wide coil of sheet metal  12  wound about a horizontal axis  14  which is mounted on the floor  16  for rotation about the axis  14 . A pair of slitting rollers  18  and  20  slit the sheet metal  12  into a plurality of strips such as shown at  22  and  24 . The slit strips  22  and  24  are then rewound at a rewind station where the individual strips are individually rewound into a plurality of smaller coils  26 . Located between the slitter rollers  18  and  20  and the rewinding station is an accumulator in the form of a pit  28  dug downwardly beneath the floor  16 . All of the foregoing is well known in the art. Accordingly, only a brief description of the same is believed to be necessary. 
     The improved system of the present invention is shown diagrammatically in  FIG. 2 . As with the prior art system, the improvement also starts with a wide coil of sheet metal  12  that is cut into strips by a pair of slitting rollers  18  and  20  and which is then rewound into a plurality of smaller coils  26 . In lieu of the pit accumulator, however, the invention utilizes a vertical accumulator  30  that is also located between the slitting rollers  18  and  20  and the rewinding station. 
     As shown in  FIG. 2 , the accumulator  30  is comprised of a mandrel  32  that is mounted for rotation about a horizontal axis  34  parallel to the axis  14  of the coil  12 . The mandrel  32  is arranged such that all of the plurality of slit strips travel upwardly and pass over the top of the mandrel. As is also best seen from  FIG. 2 , the mandrel  32  is located above the height of the coil  12  and is also above the slitters  18  and  20  and above the rewound individual smaller coils  26 . However, and as will become apparent hereinafter, the mandrel is capable of moving upwardly and downwardly as desired. 
     The details of the accumulator  30  of the present invention are shown diagrammatically most clearly in  FIG. 3 . The mandrel  32  is supported by first and second vertically extending supports  36  and  38 . These supports are mounted on either side of the sheet material so that the mandrel is properly arranged and are secured to the floor  16  at the feet  40  and  42  thereof, respectively. A horizontally extending beam  44  extends between the tops of the supports  36  and  38  to stabilize them and keep them in proper position. 
     Mounted to each of the supports  36  and  38  are upwardly extending rods  46  and  48 . The rods  46  and  48  include an external thread thereon and are mounted for rotation about their own axes. This is accomplished utilizing flange bearings  50  and  52  at the bottoms and similar bearings  54  and  56  adjacent the tops thereof. The extreme top ends of the threaded rods  46  and  48  are connected to gearboxes  58  and  60  which are interconnected by a rotating rod  62 . 
     Adjacent the upper end of the support  38  is an electric motor  64 . The motor is controlled by switches  66  also carried by the support  38 . Through gearbox  60 , rod  62  and gearbox  58 , the electric motor  64  is capable of rotating the threaded rods  46  and  48  around their own axes in either direction. 
     A mandrel holder, such as shown at  68 , includes an internally threaded bore  70  extending vertically therethrough and is adapted to fit around either of the threaded rods  46  or  48 . While only one holder  68  is shown in the drawing, it should be readily apparent that two are utilized. One is carried by the rod  46  while the other is carried by the rod  48 . A pair of pins  72  and  74  extend rearwardly from the holder  68  and are adapted to be located on either side of the vertical supports  36  or  38 . As a result, when the threaded rod  46  or  48  is rotated, the holder  68  is prevented from rotation by an interference fit between the pins  72  and  74  and the support  36  or  38  and it must, therefore, move upwardly or downwardly on the rotating threaded rod. Moving upwardly or downwardly will, of course, depend on the direction of rotation of the threaded rods  46  or  48 . 
     On the front face of each of the holders  68  is a substantially U-shaped cup member  76 . As shown at the bottom of  FIG. 3 , the cup member  76  has two sides and a bottom but is open at the top thereof. The space in between is adapted to support the ends of the axle  34  of the mandrel  32 . Thus, as the holders  68  move up and down on the threaded rods  46  and  48 , the mandrel  32  is likewise moved upwardly or downwardly. As is also shown in  FIG. 3 , the mandrel  32  can be provided with a plurality of disks  78  for separating the plurality of strips of sheet metal from each other after they have been cut. 
     Because the mandrel  32  can easily be placed into or removed from the holders  68 , it need not be in place on the accumulator  30  when the unwinding, slitting and rewinding operation begins. If, however, it becomes necessary to begin accumulating excess slack, the mandrel can be easily inserted into place and can be moved up or down, as needed. Similarly, it can be removed whenever required. 
     The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and accordingly, reference should be made to the appended claims rather than to the foregoing specification as indicating the scope of the invention.