Apparatus and method for accumulating sheets

Abstract

An accumulator device with a downward angled input transport. Downstream, an accumulating receptacle receives sheets. The accumulating receptacle has an upper guide and a lower guide forming a horizontal accumulating channel. Dump rollers act as a stop during sheet accumulation, and as a transport for removing completed accumulations from the sheet accumulating device. A rear portion of sheets buckle downward into a trap arrangement below the input rollers. Preferably, the upper guide of the accumulating channel comprises a continuously rotating belt to urge accumulating sheets against the dump rollers. Also, a positive air device may be used to assist in the buckling of the rear portion of the sheets. To assist in handling large collations, when a sheet arrives at the dump rollers the advance by a small predetermined incremental displacement slightly shingling the sheets to maintain positive control for later reliable discharge.

1 . A sheet accumulating device comprising a first accumulator including: 
 an input transport;    an accumulating receptacle downstream of the input transport and receiving sheets from the input transport, the accumulating receptacle having an upper guide and a lower guide forming an accumulating channel, the accumulating channel being substantially horizontal;    accumulation dump rollers at a downstream end of the accumulating receptacle, the dump rollers controlled to act as a stop during sheet accumulation, and to transport completed accumulations from the sheet accumulating device, the dump rollers positioned downstream from the input transport a distance less than the length of sheets to be accumulated;    a trap arrangement at an upstream end of the accumulating receptacle positioned beneath the input transport and below a level of the accumulating channel for receiving trailing portions of accumulated sheets stopped at the dump rollers and that buckle into the trap arrangement from the input transport;    wherein at least one of the lower or the upper guide comprises a continuously rotating belt to urge accumulating sheets against the dump rollers.    
   
   
       2 . The device of  claim 1  further comprising a second accumulator in parallel with the first accumulator and whereby a diverter mechanism upstream of the first and second accumulators alternately diverts sets of sheets to the second accumulator while the first accumulator is discharging a first completed accumulation, and to the first accumulator while the second accumulator is discharging a second completed accumulation.  
   
   
       3 . The device of  claim 2  further including an output transport downstream of the first and second accumulators whereby the output of the parallel first and second accumulators are merged back into a single transport path.  
   
   
       4 . The device of  claim 1  wherein the accumulation dump rollers are comprised of urethane material with a hardness in the range of 35-45 on an A-scale durometer.  
   
   
       5 . The device of  claim 1  further comprising an air pressure source positioned proximal to the trap arrangement for assisting tail portions of sheets into the trap arrangement.  
   
   
       6 . The sheet accumulating device of  claim 5  further comprising a sensor detecting a position of a sheet and the positive air source being activated based on the sensed position of a sheet.  
   
   
       7 . The sheet accumulating device of  claim 1  wherein the input transport has a downward angle relative to the accumulating receptacle thereby assisting in the buckling of the sheets into the trap arrangement.  
   
   
       8 . The sheet accumulating device of  claim 1  wherein the orientation of the device is turned upside-down thereby creating a reverse accumulating device.  
   
   
       9 . A sheet accumulating device comprising a first accumulator including: 
 an accumulating receptacle receiving a series of sheets to be accumulated;    accumulation dump rollers at a downstream end of the accumulating receptacle, the dump rollers controlled to act as a stop during sheet accumulation, and to transport completed accumulations from the sheet accumulating device;    a sensor sensing the arrival of sheets in the accumulating receptacle;    a controller controlling the dump rollers to perform a small predetermined incremental displacement upon a sensed arrival of a sheet at the dump rollers, thereby slightly shingling the sheets, the controller further causing the dump rollers to completely discharge the slightly shingled accumulation upon completion of the accumulation.    
   
   
       10 . The sheet accumulating device of  claim 9  wherein the predetermined incremental displacement is less than 0.010 inches.  
   
   
       11 . The sheet accumulating device of  claim 9  further comprising: 
 an input transport upstream of the accumulating receptacle;    the accumulating receptacle being positioned downstream of the input transport and receiving sheets from the input transport, the accumulating receptacle having an upper guide and a lower guide forming an accumulating channel, the accumulating channel being substantially horizontal;    the accumulation dump rollers being positioned at a downstream end of the accumulating receptacle and positioned downstream from the input transport a distance less than the length of sheets to be accumulated; and    a trap arrangement at an upstream end of the accumulating receptacle positioned beneath the input transport and below a level of the accumulating channel for receiving trailing portions of accumulated sheets stopped at the dump rollers and caused to buckle into the trap arrangement from the input transport.    
   
   
       12 . The sheet accumulating device of  claim 11  wherein the input transport has a downward angle relative to the accumulating receptacle thereby assisting in the buckling of the sheets into the trap arrangement.  
   
   
       13 . The sheet accumulating device of  claim 11  wherein the orientation of the device is turned upside-down thereby creating a reverse accumulating device.  
   
   
       14 . The accumulating device of  claim 11  wherein at least one of the lower or the upper guides comprises a continuously rotating belt to urge accumulating sheets against the dump rollers.  
   
   
       15 . The device of  claim 9  further comprising a second accumulator in parallel with the first accumulator and whereby a diverter mechanism upstream of the first and second accumulators alternately diverts sets of sheets to the second accumulator while the first accumulator is discharging a first completed accumulation, and to the first accumulator while the second accumulator is discharging a second completed accumulation.  
   
   
       16 . The device of  claim 15  further including an output transport downstream of the first and second accumulators whereby the output of the parallel first and second accumulators are merged back into a single transport path.  
   
   
       17 . A sheet accumulating device comprising a first accumulator including: 
 an input transport;    an accumulating receptacle downstream of the input transport and receiving sheets from the input transport, the accumulating receptacle having an upper guide and a lower guide forming an accumulating channel, the accumulating channel being substantially horizontal;    accumulation dump rollers at a downstream end of the accumulating receptacle, the dump rollers controlled to act as a stop during sheet accumulation, and to transport completed accumulations from the sheet accumulating device, the dump rollers positioned downstream from the input transport a distance less than the length of sheets to be accumulated;    a trap arrangement at an upstream end of the accumulating receptacle positioned beneath the input transport and below a level of the accumulating channel for receiving trailing portions of accumulated sheets stopped at the dump rollers and caused to buckle into the trap arrangement from the input transport; and    an air pressure source positioned proximal to the trap arrangement for assisting tail portions of sheets into the trap arrangement.    
   
   
       18 . The sheet accumulating device of  claim 17  further comprising a sensor detecting a position of a sheet and the air pressure source being activated based on the sensed position of a sheet.  
   
   
       19 . The sheet accumulating device of  claim 17  wherein the orientation of the device is turned upside-down thereby creating a reverse accumulating device.  
   
   
       20 . A method for accumulating and transporting sheets, the method comprising: 
 transporting a sheet to an accumulation receptacle;    stopping the sheet in the accumulation receptacle with accumulation dump rollers in a stopped condition;    sensing an arrival of the sheet in the accumulation receptacle;    displacing the dump rollers by a small predetermined incremental displacement upon sensing the arrival of the sheet, thereby slightly shingling the sheets;    repeating the foregoing steps for a series of sheets comprising a complete accumulation; and    discharging a completed accumulation of slightly shingled sheets from the dump rollers.    
   
   
       21 . The method of  claim 20  wherein the predetermined incremental displacement is less than 0.010 inches.  
   
   
       22 . The method of  claim 20  wherein the step of transporting the sheet to the accumulating receptacle includes transporting the sheet in an input transport plane with a downward angle, the method further comprising the steps of: 
 buckling a rear portion of transported sheets into a trap arrangement when a lead edge of the sheet stops at the dump rollers; and    urging accumulating sheets in the accumulating receptacle against the dump rollers with an urging arrangement that provides a continuous urging force while slipping over the surface of transported sheets.    
   
   
       23 . The method of  claim 21  wherein the step of buckling further includes blowing air in a downward direction to assist the rear portion of the sheet into the trap arrangement.  
   
   
       24 . The method of  claim 20  wherein prior to the accumulation of documents sheets, diverting sheets to one of at least two parallel accumulation paths, whereby sets of sheets are diverted to a second accumulator while a first accumulator is discharging a first completed accumulation, and sheets are diverted to the first accumulator while the second accumulator is discharging a second completed accumulation.  
   
   
       25 . The method of  claim 24  further including the step of merging completed accumulations from the parallel accumulation paths into a single transport path.