Patent Publication Number: US-9840389-B2

Title: Sheet stacker

Description:
FIELD OF THE INVENTION 
     This invention relates to web handling equipment that is employed peripherally to printing devices, and more particularly to devices that stack cut sheets at high speed. 
     BACKGROUND OF THE INVENTION 
     Modern printing operations often rely upon high-speed electronic printers that generate printed output on a throughput continuous web (e.g. a paper web) in a single or side-by-side series of printed pages that are (optionally) slit and cut into individual page sheets. The pages are (optionally) merged and directed downstream into a stacker that creates finished stacks for further downstream handling operations—such as binding, folding, inserting, embossing, punching, etc. The finished stacks can be used for a variety of purposes that are clear to those of skill. Sheets can be received in a stack at a speed that creates certain challenges to generating a properly aligned stack—for example, sheets should be decelerated appropriately to arrive at a proper position in the stack, and should be gripped sufficiently while transiting into the stack to avoid slippage that could result in a misaligned page. Sheets may also be subjected to aerodynamic or electrostatic forces that can affect proper entry into the stack. 
     Many contemporary stackers employ powered elastomeric wheels or belts in combination with a descending support to direct sheets into a stack. Sheets are received by the wheels/belts and driven into the stack in a desired order. As the stack grows, the support descends to make room for the growing stack height. However, high-speed delivery of sheets can tax the capabilities of such an arrangement. 
     Moreover, many sheets (substrates) are composed of (or include) materials that add challenges to the stacker and its operation. Many stackers have difficulty handling sensitive substrates, difficult media and applications with heavy or sensitive ink coverage. The thickness of the media can also challenge some stackers. Likewise, it is desirable that stackers be able to handle merged or stream folded substrates. 
     SUMMARY OF THE INVENTION 
     This invention overcomes disadvantages of the prior art by providing a stacker for use in forming stacks of cut sheets received from an upstream utilization device (e.g. a printer, cutter, etc.) that allows for positive driving of sheets into a stack using a stacking unit that includes a series of grippers that are adapted to grip and release a leading edge of each sheet at the appropriate time. In this manner, each sheet is gripped as it arrives from the upstream operation and is passed downstream into the stack, being released so as to properly decelerate at the stack&#39;s backstop. The grippers are mounted on a continuous belt (e.g. a timing belt) between a pair of opposing drive sprockets. One of the sprockets is driven by a motor (e.g. an encoder-connected motor) that is triggered to move a predetermined distance at a predetermined time. An edge sensor located upstream of the stacking unit triggers motion of the belts based signals from a controller. The grippers are actuated by a mechanical cam arrangement to selectively grip and release at predetermined positions as the belt is driven. The location of the stacking unit can be moved upstream or downstream on (e.g.) drive screws to accommodate sheets of various lengths based on information provided to the controller. A plurality of stacking units can be mounted sided by side across a width of the stacking area to accommodate wide sheets or multiple side-by-side stacks of sheets. The stacking area can include a descending elevator to accommodate growing stack sizes. 
     In an illustrative embodiment a system for stacking sheets is provided. The system includes an input drive that receives sheets from a source and directs the sheets in a downstream direction at a selected input velocity. A gripper assembly having a plurality of gripper units is provided. Each gripper unit includes a jaw member that moves between an open and a closed, gripped, position. The gripper units are mounted on a continuously moving surface that locates each of the gripper units over a stacking location, moving in the downstream direction. A controller operates the moving surface so that one of the gripper units moves to a closed position when a downstream edge of a respective one of the sheets is located at the jaw member. That gripper unit moves to an open position when the downstream edge is adjacent to a backstop in the stacking location. Illustratively, the moving surface comprises a belt located between rotating sprockets and the gripper assembly includes side plates that enclose the belt and the sprockets. The side plates can include a raceway in which a base member of each of the gripper units is guided, and the jaw member can include a cam follower that rides along a ramp when the jaw member is located over the stacking location. The gripper units can also each include a spring that normally biases the jaw member into a closed position and that is overcome by action of the cam follower in engagement with the ramp. The jaw member can include an extension finger that extends outwardly and downwardly into pressurable engagement with a top sheet at the stacking location and that defines a ramp for the sheets directed from the input drive. The extension finger can be constructed from a thin, flexible material such as spring steel. Alternatively, other flexible sheet materials such as polymer (e.g. Mylar®) can be employed to construct the extension finger. The gripper assembly can be mounted on a carriage and can be operatively connected with a drive motor located on one of the side plates or a drive shaft interconnected with a motor on the carriage. The carriage can be constructed and arranged to move upstream and downstream with respect to the stacking location based upon a length of each of the sheets. The carriage can be constructed and arranged to support at least another side-by side gripper assembly having a plurality of gripper units, each with a jaw member that moves between an open and a closed, gripped, position. The gripper assembly and the other (side-by-side) gripper assembly are each positioned to handle either wide sheets or a plurality of side-by-side streams of sheets. The stacking location can include an elevator that moves downwardly as a size of a stack of the sheets at the stacking location increases and that moves into position with a conveyor when the stack is completed. In various embodiments, an edge detector is operatively connected to the controller, which senses when each of the sheets from the input drive is a predetermined distance from the gripper assembly and thereby controls the gripper assembly. The gripper units each include another jaw member that moves between an open and a closed, gripped, position so as to define a pair side-by-side of jaw assemblies for gripping sheets. The pair of assemblies prevents racking of sheets as they are gripped and transported. At least three gripper units are provided on a continuous belt with at least one of the gripper units located on a top side of the belt. 
     In another illustrative embodiment, a method for stacking sheets with the system described-above is provided. The gripper assembly is accelerated so that the one of the gripper units moves from a home position to match the input velocity. An input sheet is driven at approximately the input velocity while it is gripped with the jaw member in the closed position. Subsequently, the sheet is decelerated as the one of the gripper units moves toward the backstop. The gripper unit is then halted at the backstop as the jaw member is moved to an open position to release the respective sheet on a stack at the stacking location. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention description below refers to the accompanying drawings, of which: 
         FIG. 1  is a schematic diagram showing an overview of a system for utilizing, cutting and stacking sheets, including a stacker assembly employing a gripper assembly according to an illustrative embodiment; 
         FIG. 2  is a diagram of the stacker assembly of  FIG. 1 ; 
         FIG. 3  is a more detailed diagram of the stacker of  FIG. 2  showing the gripper assembly and associated carriage; 
         FIG. 4  is a perspective diagram of the gripper assembly of the stacker of  FIG. 1  showing an on-board drive motor; 
         FIG. 5  is a partially exposed perspective view of the gripper assembly of  FIG. 4  showing the gripper units mounted on a belt between sprockets and a ramp that actuates cam followers of respective gripper units; 
         FIG. 6  is another partially exposed perspective view of the gripper assembly of  FIG. 4 ; 
         FIGS. 7-9  are each perspective views of a gripper unit of the gripper assembly of  FIG. 4 ; 
         FIG. 10  is a flow diagram of a control and sheet motion process for the stacker of  FIG. 1 ; 
         FIG. 11  is a schematic diagram of the arrangement of input drive and gripper assembly elements for an exemplary driven sheet shown as the gripper assembly is about to receive a sheet in accordance with the process of  FIG. 10 ; 
         FIG. 12  is a schematic diagram of the arrangement of  FIG. 11  with the driven sheet gripped at the grip point by the gripper assembly in accordance with the process of  FIG. 10 ; and 
         FIG. 13  is a schematic diagram of the arrangement of  FIG. 11  with the driven sheet released by the gripper assembly adjacent to the backstop point in accordance with the process of  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a schematic view of a sheet handling system  100  according to an exemplary embodiment. The exemplary system  100  includes a utilization device  110  in which a continuous web of (e.g.) paper  112  enters from an upstream source (not shown) that can be a driven roll or the output from another utilization device. Illustratively, the utilization device can be an electronic/ink jet printer or another device that applies information or modifications to the throughput web  112 . The web exits the utilization device and can be accumulated in a loop  114  or other geometry. The utilization device handles and drives the web  112  based upon a controller  116  of known or custom design. The web  114  enters a downstream cutter  120 . The cutter is controlled by a controller  122  that drives the web and also activates a cutting blade arrangement  124  of any acceptable design (e.g. a guillotine-type cutter, a spiral, blade cutter, a cross cutter, etc.). The cutter  120  generates cuts in the web at desired positions so as to create individual sheets  126 . The controller  122  determines where cuts should occur based upon tracking of the web motion. Such tracking can include reading of motion signals from the drive assembly  128 ,  130  and/or the use of edge detectors and/or tracking of printed marks on the web. 
     The cutter  120  can include various slitting elements so that a plurality of side-by-side sheets can be produced from a single wide web by cutting it along its width (wherein “length” herein is aligned along the upstream-to-downstream driving direction of the web and “width” is aligned transverse to the length). An example of a sheet cutting and slitting arrangement is shown and described in commonly assigned U.S. Published Patent Application No. US 2013/0112055 A1, entitled SHEET SLITTING MECHANISM WITH AUTOMATED SIZE ADJUSTMENT, by Steven P. Lewalski and Bruce J. Taylor, filed Nov. 7, 2011, the teachings of which are incorporated herein by reference as useful background information. 
     Output sheets  126  from the cutter  120  are driven by the drive assembly  130  down a ramp  142  of the stacker assembly  140  according to an illustrative embodiment. Each sheet is driven at a controlled speed via the stacker sheet drive assembly  144 . A controller  146  operates the various functions of the stacker  140 . Each sheet passes an optical (or other type of) edge detector  148  that transmits a signal to the controller  146 . This signal regulates the timing of a gripper assembly  150  according to an embodiment. The gripper assembly  150  overlies a stacking area  152  that supports a sheet stack  154  having cut sheets of a desired size and shape. The stack  154  is built on a support assembly  156  that reciprocates upwardly and downwardly (double arrow  158 ), gradually descending based on the operation of an elevator assembly  160 . The elevator assembly can be implemented as any acceptable actuation mechanism—including, but not limited to, a (worm) drive screw arrangement, a fluid piston, a linear motor and/or rack-and-pinion arrangement. The entire support assembly  156 , including the gripper assembly  150  is movable in an upstream or downstream direction (double arrow  162 ) to accommodate sheets of differing lengths. The length can be adjusted, based upon controller signals, using an appropriate actuation assembly  166 . The actuation assembly can be implemented using a variety of mechanisms—including, but not limited to, a (worm) drive screw arrangement, a fluid piston, a linear motor and/or rack-and-pinion arrangement. A user interface  170  can be employed to enter sheet length and other pertinent data to the controller  146  and/or other system components. Any acceptable user interface arrangement can be employed, including, but not limited to, a display, keyboard, mouse and/or touchscreen. 
     As described further below, the gripper assembly  150  is powered by a gripper drive motor that rotates (double curved arrow  180 ) a belt assembly  182  to cause grippers  184  to selectively engage a leading (downstream) edge of each sheet as it is driven down the ramp  142 . The grippers  184  interact with a cam arrangement (described below) to selectively open and close the grippers at appropriate times. In this manner, sheets are engaged by the grippers as their respective leading edges drive under the gripper assembly  150  (and into the stack  154 ), and are disengaged as the sheets contact a movable backstop  190 , that forms the downstream edge of the stack  154 . In this embodiment, the backstop  190  underlies the gripper assembly  150 . Each disengaged gripper  184  passes out of the stacking area and rotates to the top of the assembly on its way to the next input sheet. 
     The stacker assembly  140  is shown in greater detail in the embodiments of  FIGS. 2 and 3 . The gripper assembly  150  is mounted on a moving (upstream/downstream) carriage  210  along with the backstop  190 . The carriage  210  is driven by parallel, spaced-apart lead screws  220 , extending upstream/downstream, that rotate in unison to adjust the upstream/downstream position of the carriage  210  based on sheet length. The controller  146  can include a circuit and/or process that computes (using an algorithm or look-up table) the appropriate adjustment for a given sheet length. A drive motor and transmission arrangement (not shown) responds to signals from the controller to rotate the screws  220 . Note that the backstop  190  is movable in an upstream/downstream direction over a limited range with respect to the carriage  210 , and is moved from a resting state (under bias of a spring  332 ) by a rotating cam  320  and cam follower  330 . The backstop pivots on a pivot shaft  334  extending through the gripper assembly  150 . This motion causes justification of the downstream edge of the stack  154 . 
     The cam  320  rides on a splined shaft  230  that extends between bearings on opposite sides  240  of the carriage  210 . The splined shaft  230  passes through the downstream (rear) drive sprocket of the gripper assembly  150 . The gripper assembly  150  is further supported by a transverse rod  232  upstream of the shaft  230 , which also extends between the opposing sides  240  of the carriage  210 . Because the shaft  230  is splined, the gripper assembly  150  can adjustably slide along it between the two carriage sides  240 . The gripper assembly  150  includes a collet base  350  that can include set screws (not shown), or other locking components, that secure the assembly  150  in a side-to-side location in the carriage with respect to the transverse rod  232 . In operation, the gripper assembly  150  can be moved side-to-side to be optimally located for the input sheets. Additionally, a second or third gripper assembly can be mounted on the shaft  230  and rod  232  to handle wider sheets or side-by-side slit sheets. 
     In an illustrative embodiment, the stack support can comprise a plate or a plurality of parallel rods mounted on a framework that moves upwardly and downwardly in a reciprocating manner, descending as the stack grows. The reciprocating motion can be used to compress the stack as it grows in height. A stack height sensor is used to set the maximum height of the support each time it ascends to the compressed position. In alternate embodiments, the stack support can descend at a metered rate based on the number of sheets entering into the stack. It should be clear to those of skill that a variety of mechanisms can be used to support the stack. Completed stacks can be lowered by the support so that the rods pass between conveyor belts. The completed stack, thus, is deposited onto the conveyor belts, and is then transported by the conveyor (represented by arrow  190 ) to an output location for further processing (e.g. binding). 
     With reference now to  FIGS. 4-6 , the gripper assembly  150 , according to an illustrative embodiment, is shown in further detail. As described above, the gripper assembly can be adjustably mounted in the stacker. Likewise a plurality of gripper assemblies can be mounted side-by-side as appropriate. Each gripper assembly defines a discrete module with its own power source and interconnection to the stacker&#39;s controller  146 . 
     As shown in  FIG. 4 , the gripper assembly  150  is enclosed within a pair of opposing side plates  410  and  412 . This embodiment employs an onboard drive motor  420 . The motor receives control and power from the controller  146  and drives a transmission (e.g. timing belt  424 ) to rotate a drive sprocket  424 . This drive sprocket is interconnected to the main gripper drive shaft. In alternate embodiments, as described above, the drive motor can reside on a common shaft (e.g. splined shaft  230 ) and drive the gripper(s). 
     With further reference to  FIGS. 5 and 6 , the gripper assembly is shown exposed with the side plate  410  removed. As shown, the gripper assembly  150  consists of two sprockets  510  and  520 . The upstream sprocket  510  resides on the gripper drive shaft  512 , which is operatively connected to the drive motor  420 . The sprockets  510  and  520  support a timing belt  530 , upon which resides at least three gripper units  184 . The number of gripper units  184  can vary based upon the size of the belt  530  and its speed of operation. In general, the sprocket and/or the timing belt can be modified to allow secure attachment of the gripper unit(s)  184  to the belt while providing clearance for the intermeshing timing belt teeth. In an embodiment, a tooth can be removed from the sprocket where it engages a fastener (holding the gripper unit to the belt) placed through the belt so that the fastener does not bind with the sprocket. Other arrangements, such as a belt tooth that doubles as a fastener nut or rivet base can be employed. 
     Notably, the gripper units  184  each include respective guide bearings  540  that ride in an ovular raceway groove  550  formed on the inside surface of each side plate  410  and  412 . The geometry of the gripper units  184  is described further below. The shape of the grooves  550  ensure that each gripper unit maintains a fixed path as the timing belt  530  is rotated. The rotation of the timing belt  530  occurs according to a programmed acceleration and velocity profile, also described further below. 
     With reference also to  FIGS. 7-9 , the gripper units  184  are shown and described in further detail. The gripper unit  184  includes a base member  710  upon which the guide bearings  540  are mounted. The base includes mounting holes  720 ,  722  that receive fasteners interconnecting the base member  710  to the timing belt  530 . The base member further defines a pair of platforms  730 . The platforms  730  are positioned opposite extensions  742  of the movable jaw members  740 . In this embodiment, the jaw members are separate units located on each opposing side of the base member  710 . In an alternate embodiment, the jaw member can be a single piece spanning across the width of the base member. Each jaw member  740  rides on a pivot axle  910  ( FIG. 9 ), mounted near the base member platform  730 . The pivot axle  910  is positioned so that the jaws move toward and away from the base member to, respectively, grip and release a sheet. The jaw members  740  are each normally biased away from the respective platforms  730  by a compression spring (or similar biasing member) (not shown) located in opposing wells between the jaw member and the base member. A variety of alternate spring arrangements (e.g. a torsion spring, a tension spring, etc.) can be employed in a manner clear to those of skill. By biasing the platform  730  away from the jaw extension  742 , the mouth  750  of each gripper pair (i.e. a jaw and an anvil portion  752  of the base member) is normally biased closed. The amount of pressure exerted by the gripping mouth is variable. Likewise, the surface of the jaw and/or platform can be smooth, textured or coated with an elastomer as appropriate to the sheet feeding requirements. 
     Each jaw member includes a lever arm that extends between the guide bearings  540 . The distal end of the lever arm  760  (opposite the jaw member  740 ) carries a roller  762 . With reference to  FIG. 5 , the roller is arranged to contact a ramp  570  having a surface shape that causes the lever arm  760  to move as the belt drives the gripper unit  184  along the length of the ramp. In this manner, the opening and closing of the gripper mouth  750  is actuated by the relative position of the roller  762  and lever arm with respect to the ramp. As depicted, the ramp  570  has a thicker (more downwardly extended) region near its front section  572 —thereby causing the gripper to open and receive a driven sheet into the mouth  750 . The mid section  578  of the ramp  570  is thinner (more upwardly extended), causing the mouth  750  to close, gripping the sheet. The rear section  576  of the ramp  570  is, again, thicker, causing the gripper mouth  750  to open and release the sheet as it contacts the backstop ( 190  in  FIGS. 1-3 ). A ramp is secured to each side plate  410 ,  412  of the gripper assembly  150  so as to actuate each jaw  740  in the gripper unit  184 . 
     Note that the mouth is constructed with a V-shaped cross section that assists in funneling the leading edge of each sheet into the confronting surfaces of the mouth  750 . Additionally each jaw  740  includes a forwardly (in the upstream direction) and downwardly directed flexible extension finger  760 . The extension finger  760  is pointed near its front end  762 . It can be constructed from a durable, thin material, such as spring steel. Alternatively another type of lightweight material, such a polymer sheet (e.g. Mylar) can be used to form the finger. It serves to bias the sheets in the stack downwardly while providing a ramp that assists in directing the next input sheet upwardly into the gripper mouth  750 . This geometry thereby avoids input sheets undercutting the existing stack and further assists in compressing the existing stack to remove air bubbles, etc. The extension member can extend 1-3 centimeters away from the jaw member  740  and can be directed 0.5-1 centimeter below the jaw member in an embodiment. The finger can include a tapered tip as shown, with a rounded over end to prevent digging into sheets. In various embodiments, the finger can define a permanently curved surface that reduces (but does not eliminate) pressure on the sheets in the stack. 
     Reference is now made to the procedure  1000  of  FIG. 10  and schematic diagram of  FIG. 11 , showing the relative position of the input sheet  1110 , input drive (nip rollers)  144 , gripper assembly  150 , and respective gripper units  184   a ,  184   b  and  184   c . As shown, the gripper  184   a  is located in the “home” position, awaiting the input sheet  1110 , which is driven (arrow  1112 ) by the rollers  144  after it has been cut by the cutter in procedure step  1010 . Note that the gripper  184   a  is shown with lever arm roller  762  that acts as a cam follower riding along the ramp  570  to control the relative open/closed position of the gripper jaw. Per step  1020 , when the edge of the sheet reaches a distance D START , from the gripper  184   a , the gripper assembly (and associated gripper  184   a ) accelerates over a distance D ACCEL . This distance can be established based upon an encoder, tied to the cutter and drive and/or the above-described edge sensor  148 . Then, as the input sheet  1110  (driven at a faster speed than the accelerating gripper  184   a ) catches up with the gripper, it overlaps the extension finger  760  and the gripper jaw closes from full open (8 degrees) to partially open (3 degrees) in step  1030 . The gripper  184   a  moves over a distance D GRIPPED  in this phase. In step  1040 , the sheet  1010  matches the gripper speed and the gripper moves to close fully at the grip point  1120 . This configuration is illustrated in  FIG. 12 . The gripper  184   a  is now fully closed in step  1050  while the sheet passes through the distance D NIP  with the upstream edge of the sheet  1010  still grasped within the rollers  144 . Then, in step  1060 , the gripper  184   a  and rollers  144  travel at the same velocity, the upstream edge of the sheet exits the nip of the rollers  144  and is carried exclusively by the gripper  184   a  toward the backstop  190 . This state continues over distance D CONST . The gripper  184   a  then begins to decelerate in step  1070  as it approaches the backstop  190 , over a distance D DECEL . This condition is shown in  FIG. 13 . The gripper  184   a  begins to open to release the sheet  1010  as its downstream (leading) edge contacts the backstop  190  (step  1080 ). In step  1090 , the gripper  184   a  moves away from the sheet  1010  and closes again (having disengaged from the ramp  570 ). A new gripper  184   c  moves into the home position awaiting input of the next sheet. 
     In an embodiment, the total operating distance D TOTAL  for the gripper ( 184   a ) in a sheet feeding/staking operation as described above is approximately 80 millimeters. The exemplary parameters for other distances are as follows, and are approximate: 
     D START =53.3 millimeters 
     D ACCEL =26.7 millimeters 
     D GRIPPED =2.8 millimeters 
     D NIP =15.0 millimeters 
     D CONST =0.0 millimeters 
     D DECEL =35.6 millimeters 
     These exemplary parameters should apply to a wide range of sheet lengths with appropriate upstream/downstream placement of the gripper assembly relative to the rollers  144 . A sheet of 140 millimeters in length is provides as an example and is driven at approximately 3556 millimeters per second at maximum velocity. 
     In alternate arrangements, the number of gripper units on a belt  530  can be widely varied. Likewise, the operating distance of the gripper can be varied by altering the dimensions of the gripper assembly  150 . More generally, the arrangement of drive rollers ( 144 ) can be varied and other forms of driving units (e.g. driving belts) can be provided in alternate embodiments. 
     It should be clear that the gripper assembly as described herein provides an effective mechanism for the high speed stacking of sheets that avoids misfeeds and damage to stack sheets. The assembly allows for flexible sheet handling in terms of length, width and number of side-by-side stacks. Additionally, the stacker effectively operates with sheets/substrates composed of (or including) materials that add challenges to the stacker and its operation. The stacking arrangement can effectively handle sensitive substrates, difficult media and applications with heavy or sensitive ink coverage. The stacker arrangement can also operate with media of various thicknesses and/or merged or stream folded substrates. 
     The foregoing has been a detailed description of illustrative embodiments of the invention. Various modifications and additions can be made without departing from the spirit and scope of this invention. Features of each of the various embodiments described above may be combined with features of other described embodiments as appropriate in order to provide a multiplicity of feature combinations in associated new embodiments. Furthermore, while the foregoing describes a number of separate embodiments of the apparatus and method of the present invention, what has been described herein is merely illustrative of the application of the principles of the present invention. For example, as used herein the terms “process” and/or “processor” should be taken broadly to include a variety of electronic hardware and/or software based functions and components (and can alternatively be termed functional “modules” or “elements”). Moreover, a depicted process or processor can be combined with other processes and/or processors or divided into various sub-processes or processors. Such sub-processes and/or sub-processors can be variously combined according to embodiments herein. Likewise, it is expressly contemplated that any function, process and/or processor herein can be implemented using electronic hardware, software consisting of a non-transitory computer-readable medium of program instructions, or a combination of hardware and software. Additionally, as used herein various directional and dispositional terms such as “vertical”, “horizontal”, “up”, “down”, “bottom”, “top”, “side”, “front”, “rear”, “left”, “right”, and the like, are used only as relative conventions and not as absolute directions/dispositions with respect to a fixed coordinate space, such as the acting direction of gravity. Additionally, where the term “substantially” or “approximately” is employed with respect to a given measurement, value or characteristic, it refers to a quantity that is within a normal operating range to achieve desired results, but that includes some variability due to inherent inaccuracy and error within the allowed tolerances of the system (e.g. 1-5 percent). It is also contemplated that the sheet pathway can include additional sensors, such as presence sensors, jam sensors, etc. that are operatively connected with the controller in a manner clear to those of skill. Likewise, the operation of the stacker and associated gripper assembly can be coordinated with the operation of the cutter and other handling units via the controller and associated interconnections therebetween. Accordingly, this description is meant to be taken only by way of example, and not to otherwise limit the scope of this invention.