Abstract:
A sheet and stack feeding mechanism comprising an accumulating area, a mechanism for feeding sheets into the accumulating area, a pair of exit rollers and a mechanism for moving the stack of sheets out of the accumulating area through the exit mechanism, the exit roller being resilient to permit stacks of various thickness to pass therethrough.

Description:
RELATED APPLICATION 
     This application is a continuation in part of U.S. patent application Ser. No. 09/902,996 filed Jul. 12, 2001. 
    
    
     BACKGROUND 
     The present invention relates to a sheet and stack feeding mechanism and more particularly to a mechanism for accumulating sheets in a stack and discharging them as a stack. 
     In present high speed sheet feeding mechanisms, sheets are fed one by one to an accumulating area where sheets accumulate in a stack. When a certain number of sheets have been deposited in the stack, the entire stack is moved out of the accumulating area to another machine or to another portion of the machine. In current sheet feeding mechanisms, printed sheets are subject to being smudged when they are moved out of the accumulating area. This is especially true if transport belts are used in the accumulating area to move the sheets and stack into and out of the accumulating area. Furthermore, the mechanism for removing the entire stack out of the accumulating area usually must be adjusted in order to accommodate stacks of different thicknesses. In addition, it is sometimes desirable to feed and stack the sheets in the accumulating area one below the other. In existing machines, it has been difficult to do this without readjusting the entire machine. Moreover, existing machines, do not have the versatility of permitting sheets to be accumulated one on top of the other or one beneath the other. 
     OBJECTS 
     The present invention overcomes these difficulties and has one its objects the provision of an improved sheet feeding mechanism in which a stack of sheets can be easily moved out of the accumulating area. 
     Another object of the present invention is the provision of an improved sheet feeding mechanism in which a stack of sheets may be easily moved out of an accumulating area without smudging. 
     Another object of the present invention is the provision of an improved sheet feeding mechanism in which the same mechanism can be used to move stacks of sheets of various thicknesses out of the accumulating area. 
     Another object of the present invention is the provision of an improved sheet feeding mechanism in which sheets can be accumulated in an accumulating area one under the other. 
     Another object of the present invention is the provision of an improved sheet feeding mechanism which can be easily converted to feed and stack sheets one beneath the other or one above the other. 
     Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to described, or will be indicated in the appended claims and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice. 
    
    
     DRAWINGS 
     A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings forming a part of the specification, wherein: 
     FIG. 1 is a schematic side elevational view of the present invention. 
     FIG. 2 is a schematic perspective view thereof. 
     FIG. 3 is a schematic front view of a portion of the mechanism shown in FIG.  1 . 
     FIG. 4 is a schematic fragmentary side elevational view of another embodiment of the present invention. 
     FIG. 5 is a schematic fragmentary side elevational view of another embodiment of the present invention. 
     FIG. 6 is a schematic fragmentary side elevational view of another embodiment of the present invention. 
    
    
     DESCRIPTION 
     Referring to the drawings and to the embodiment shown in FIGS. 1-3, sheets of paper P are fed one by one into an accumulating area A where they accumulate in a stack S. The accumulating area A comprises a front gate  1 , rear pusher or kicker  2  and superimposed cables or rods  3  and  6  between which the sheets P are accumulated and a ramp  4  over which the sheets P pass. Alternately, the sheets P may accumulate on an accumulating bay or platform  5  (FIG.  2 ). In either event, there are no transport belts in the accumulating area A so that the sheets P are not continuously rubbed as they are being deposited. 
     A plurality of pairs of superimposed exit pinch rollers  10  are provided in front of the accumulating area A to direct the stack S from the accumulating area A to another portion of the machine (not shown). The front gate  1  is pivotally mounted on shaft  7  to swing back and forth from a raised position in front of the stack S to act as a gate or stop for the stack S of sheets P in the accumulating area A to a lowered position out of the way of the stack S so as to free the stack S of sheets P to move forward. The rear pusher  2  is adapted to swing back and forth on shaft  8  from a raised position behind the trailing edges T of the sheets P to a forward position where it strikes the trailing edge T of the stack S of sheets P to push it forward and through the exit pinch rollers  10  as a unit. The movement of the front gate  1  and the rear pusher  2  are coordinated so that when the rear pusher is swung forward to push the stack S, the front gate  1  is moved down and out of the way to allow the stack S to move forward. An air spray mechanism  11  may be provided across the top of the accumulating area A to provide an amount of air to tamp the sheets P and maintain the sheets P flat on the stack S as they are deposited thereon. 
     In front on the release gate  1  the exit pinch rollers  10  are rotatable on shafts  9  and are made of a resilient material which preferably may be a polyurethane resilient foam which has a low to medium density. They are resilient enough to be compliant or easily squeezed by thick stacks S but also have a coefficient of surface friction high enough to grasp and move the stacks S forward between them as a unit. These factors allow for transporting the stack S of printed sheets P through the exit pinch rollers  10  as a unit without smudging any of the printed sheets P. In addition, the compliancy and resilience of the foam of the exit pinch rollers  10  permit stacks of different heights to be moved through the exit pinch rollers  10  without the necessity of adjusting the distance between them. When a sufficient number of sheets P have been deposited in the accumulating area A, control means (not shown) sense the height of the stack and activate the pusher  2  and gate  1  so that the pusher  2  is swung forward to push the stack while the release gate  1  is swung down to free the stack for forward movement. The pusher  2  pushes the trailing edges T of the sheets P in the stack S to move the entire stack S (as a unit) out of the accumulating area A through the resilient exit pinch rollers  10  which grasp that stack S and move it forward. 
     Referring to the embodiment of FIG. 4, in which the reference characters used for some parts are the same as the reference characters used in the embodiment of FIGS. 1-3 for the same parts, the mechanism shown is adapted to permit sheets P to be stacked one under the other. A support mechanism, such as a brush  15 , is provided in the accumulating area A and extends there into from the bottom. When a previous sheets p 1  is moved into the accumulating area A, the brush  15  allows the leading edge L of the previous sheet p 1  to pass through to the release gate  1  but holds the trailing edge T of the previous sheet p 1  in a raised or uplifted position so that the leading edge of a subsequent sheet p 2  can pass beneath the bottom of the previous sheet p 1 . This continues with each sheet being fed until the desired stack quantity is reached. The brush  15  can be a freely rotatable or stationary round brush. The brush may also be an angled straight brush  16  as shown in the embodiment of FIG.  5 . In either instance, the brush  15  or  16  may be made of conductive material to eliminate static electricity. As another alternative, as shown in FIG. 6, an air knife or air brush  17  may be provided to direct air against the trailing edge T of the previous sheet p 1  to keep the trailing edge T of the first sheet p 1  in a raised position until the leading edge L of the subsequent sheet p 2  is moved underneath it. 
     As shown in FIG. 4, the brush  15  is movable up and down relative to the accumulating area A. This permits the same mechanism to be used for stacking sheets P one on top of the other and for accumulating the sheets by understacking them one beneath the other. When the sheets P are to be stacked one on top of the other, the brush  15  is moved down out of the way and below the cable  3  so that sheets P moving into the accumulating area A will lie on the cable  3  and will accumulate one on top of the other. Since the brush  15  is down and out of the way, the sheets P will not strike the brush  15 . However, when it is desired to understand the sheets and have the sheets accumulate one under the other, the brush  15  is raised so that now the sheets coming into the accumulating area A will strike the brush  15  and the rear end of a sheet P 1  will be held in an elevated position until a second sheet P 2  is fed into the accumulating area A under the first sheet P 1 . When it is desired to again accumulate sheets one on top of the other, the brush  15  is again lowered out of the way. Hence, this invention provides a mechanism with the versatility for stacking one on top of the other or one under the other. 
     A similar versatility provided in the embodiment shown in FIG. 5, brush  16  may be pivoted from an upper position in the path of the sheets P or to a lower position below the cable  3  and out of the sheet path (not shown) so that the sheets P may accumulate one on top of the other. When the brush  16  is raised, the sheets accumulate one below the other. The alternative shown in FIG. 6 is similarly versatile. If it is desired to accumulate the sheets one on top of the other, the air brush  17  may either be shut off or moved out of the way in order to permit the sheets to accumulate one over the other or the air brush  17  may be turned on or the air brush  17  may be moved back under the rear of the assembly area A so that it impinges on the rear edge T of the incoming sheets P and keeps the rear edge T of a first sheet P 1  elevated until another sheet P 2  is fed into the accumulating area A under a first sheet P 1 . 
     It will thus be seen that the present invention provides an improved sheet and stack feeding mechanism in which a stack can be easily moved out of the accumulating area, in which the same mechanism can be used to move stacks of sheets of various thicknesses out of the accumulating area, in which sheets may be accumulated in the accumulating area one under the other which may be easily connected to feed sheets one over the other or one below the other and which is simple to use and inexpensive to manufacture and maintain. 
     As many and varied modifications of the subject matter of this invention will become apparent to those skilled in the art from the detailed description given hereinabove, it will be understood that the present invention is limited only as provided in the claims appended hereto.