DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

[0019] Referring now to the drawings wherein the showings are for the purpose of illustrating the preferred embodiment of the invention only, and not for the purpose of limiting same, FIGS. 1 - 3 show a sheet stacking device 10 illustrating a preferred embodiment of the present invention. Sheet stacking device 10 is adapted to receive individual sheets, designated S, of a generally planar material at a first position relative thereto, and to stack such sheet onto a vertical stack at a second position. In the embodiment shown, sheet stacking device 10 is basically comprised of a support structure 20 , right and left gripper/stacker assemblies 40 R, 40 L, a stacking assembly 200 and a control assembly 250 .

[0020] In the embodiment shown, support structure 20 is comprised of a mounting plate 22 that is supported by a pair of spaced-apart vertical posts 24 . Posts 24 may be part of an existing machine, or may be separate therefrom and fixedly secured in place by other means. Plate 22 is mounted to posts 24 in a generally vertical orientation. A pair of parallel, spaced-apart rails 26 extend across one face of mounting plate 22 . An elongated housing 32 having a slot 32 a formed therein is disposed between rails 26 in parallel relationship therewith. A lead screw 34 is mounted within housing 32 and extends axially therethrough. A hand wheel 36 and one end of housing 32 is operable to rotate lead screw 34 by conventionally known mechanical means.

[0021] Right and left hand gripper/stacker assemblies 40 R and 40 L are mounted on mounting plate 22 and are spaced apart from each other as shown in the drawings. Right and left gripper/stacker assemblies 40 R, 40 L are essentially mirror images of each other. Accordingly, only one gripper/stacker assembly 40 L shall be described in detail, it being understood that such description applies equally to the other gripper/stacker assembly 40 R. In the drawings, like components are designated with like reference numbers, with the suffixes “R” or “L” denoting a component in right (R) gripper/stacker assembly 40 R or a component for left (L) gripper/stacker assembly 40 L.

[0022] Gripper/stacker assembly 40 L includes a support frame 42 L that is comprised of a generally flat platform 44 L and an elongated brace 46 L that extends therefrom, as best seen in FIG. 2 . Platform 44 L is generally a flat plate having a first surface 44 a L and a second surface 44 b L. Four (4) slide members 52 L are mounted on surface 44 a L and are disposed to ride upon rails 26 , as best seen in FIG. 2 . A carriage mount 54 L having a threaded opening therethrough is adapted to receive lead screw 34 . In this respect, rotation of lead screw 34 by hand wheel 36 causes platform 44 L to ride along rails 26 . At the upper end of platform 44 L, a sheet support 62 L is provided. Sheet support 62 L is mounted to platform 44 L by a bracket 64 L, wherein sheet support 62 L assumes a generally horizontal orientation.

[0023] Referring now to brace 46 L, best seen in FIG. 2 , an elongated housing 72 L having a slot 72 a L therein extends along the surface of brace 46 L. A gripper lead screw 74 L is mounted axially within housing 72 L. A motor 76 L is mounted at the free end of brace 46 L and is connected to one end of lead screw 74 L by conventional means (not shown). Motor 76 L is operable to turn lead screw 74 L. Motor 76 L is preferably a stepper motor, having means for sensing the angular position thereof.

[0024] An elongated track 82 L, best seen in FIGS. 1 and 3 , extends along brace 46 L above, and parallel to, lead screw 74 L. Track 82 L, together with lead screw 74 L, is adapted to support a gripper mechanism 90 L, best seen in FIG. 3 . Gripper mechanism 90 L includes a gripper carriage 92 L having an upper arm 94 L, and a lower arm 96 L. A slide member 98 L, mounted on carriage 92 L is dimensioned to receive track 82 L and slide therealong. Carriage 92 L also includes a lead screw mount 102 L having an opening therein dimensioned to operatively receive lead screw 74 L, wherein rotation of lead screw 74 L causes gripper carriage 92 L to move along track 82 L.

[0025] Upper arm 94 L includes a downwardly extending post 104 L, and lower arm 96 L includes an upwardly extending post 106 L, as best seen in FIG. 2 . Posts 104 L, 106 L are generally aligned with each other. The facing ends of posts 104 L, 106 L are spaced apart to form a gap therebetween. Mounted to post 104 L is a generally C-shaped bracket 112 L that has spaced-apart leg portions 112 a L between which extends a pin 114 L. An upper friction roller 116 L and a pulley 118 L are fixedly mounted on pin 114 L, as best seen in FIG. 3 . Pulley 118 L is adapted to receive a drive belt 122 L. Drive belt 122 L is operatively attached to a pulley 124 L that is mounted on a shaft of a motor 126 L. Motor 126 L is operable to drive belt 122 L to rotate friction roller 116 L.

[0026] Referring now to post 106 L on lower arm 96 L, a rotary actuator 132 L is mounted thereto. Actuator 132 L is connected to a linkage 134 L. Linkage 134 L is comprised of a first lever arm 136 L, a second lever arm 138 L, and a connecting rod 142 L. First lever arm 136 L is pivotally connected to actuator 132 L. A lower friction roller 144 L is rotatably mounted at the free end of second lever arm 138 L. Lower friction roller 144 L is disposed to be in alignment with upper friction roller 116 L. Linkage 134 L is operable to move lower friction roller 144 L towards, and away from, upper friction roller 116 L upon actuation of rotary actuator 132 L.

[0027] Referring now to stacking mechanism 160 L, lateral support for a sheet S is provided by a rotary element 162 L, as best seen in FIG. 3 . Rotary element 162 L is comprised of an elongated shaft 164 L having a plurality of outwardly extending, angularly, spaced-apart fins 166 L. In the embodiment shown, four (4) radially extending, equally spaced fins 166 L are shown. Shaft 164 L and fins 166 L are preferably formed of a metal or a rigid plastic. Guide strips 168 L are mounted on one side of each fin 166 L, as best seen in FIG. 3 . Shaft 164 L is supported at one end by a bracket 172 L that extends from brace 46 L, and at the other end by an annular bracket 174 L, mounted to platform 44 L. Shaft 164 L is mounted to be generally parallel to track 82 L, and such that an exposed surface on a strip 168 L can be positioned to be coplanar with the surface of sheet support 62 L, as best seen in FIG. 2 .

[0028] A pulley 182 L is mounted to shaft 164 L adjacent to annular bracket 174 L, as best seen in FIG. 2 . A drive belt 184 L is mounted on pulley 182 L. Belt 184 L is mounted to a pulley (not shown) mounted on a shaft of a motor 188 L. Motor 188 L is mounted on platform 44 L and is operable to drive belt 184 L, and in turn, to rotate shaft 164 L. Like motor 126 L, motor 188 L is preferably a stepper motor, wherein the annular position of shaft 164 L may be accurately determined and controlled.

[0029] Stacking assembly 200 is disposed below and between right gripper/stacker assembly 40 R and left gripper/stacker assembly 40 L. Stacking assembly 200 is generally comprised of a stacking platform 202 supported by a movable support. In the embodiment shown, stacking platform 202 is supported on a rod 204 that extends from a base (not shown). Stacking platform 202 is preferably operable to move downward a predetermined distance each time a sheet S is stacked thereon. In this respect, stacking platform 202 may be supported by a compression spring (not shown), wherein stacking platform 202 is lowered as the weight thereon increases. Alternately, rod 204 may be comprised of a conventional, hydraulic or pneumatic cylinder, or mechanical screw device, that is operably controlled to lower a stacking platform 202 after a predetermined number of sheets have been stacked thereon.

[0030] Referring now to FIG. 4, a block diagrammatic representation of a control system 250 for sheet stacking device 10 is shown. The physical operation of sheet stacking device 10 is basically controlled by a central processing unit 222 which is programmed to control operations of the various components of sheet stacking device 10 by means of a program stored therein. Central processing unit 222 is operably connected to lead screw drive motors 76 R, 76 L, friction wheel drive motors 126 R, 126 L, rotary actuators 132 R, 132 L and shaft drive motors 188 R, 188 L. In this respect, central processing unit 222 controls the operation of such components, and at the same time, receives information back from such components as to their relative positions. In this respect, as indicated above, the aforementioned motors preferably include position-sensing means to provide an indication of their relative positions of the shaft of such motors, which, in turn, provides central processing unit 222 with an indication of the relative positions of the associated components.

[0031] In addition to the foregoing, an input device 224 , such as a key pad, mouse or touch-screen panel, is provided to allow users to re-program central processing unit 222 to modify operations of sheet stacking device 10 , as shall be described in greater detail below. Further, a scanner 226 , shown in FIG. 5 G, may be used to detect and monitor the quality of the sheets to be stacked and to provide a signal to central processing unit 222 identifying defective sheets that should be discarded from the stack. Still further, central processing unit 222 may receive signals from an auxiliary device, such as a sheet feeder or cutting device 310 to provide an indication as to the operation thereof.

[0032] Referring now to FIGS. 5 A- 5 G, sheet stacking device 10 shall further be described with respect to its operation. In FIGS. 5 A- 5 F, sheet stacking device 10 is shown together with a sheet cutting device 310 that is operable to cut a generally continuous length of material M into sheets S of a desired length. Sheet cutting device 310 , in and of itself, forms no part of the present invention, and is shown solely for the purpose of illustration. Sheet cutting device 310 merely represents a source of “cut-to-length sheets” S to be stacked. It will be appreciated from a further reading of the specification, that sheets S need not be cut from a continuous roll, but may be formed in a flat, planar configuration by any suitable process.

[0033] In the particular embodiment shown, material M to be cut into sheets S is guided along a predetermined path by guide rollers 312 . A cutting assembly 314 is provided along the path to cut material M into sheets S of predetermined lengths. In the embodiment shown, cutting assembly 314 is comprised of a movable, upper cutting die 316 and a stationery lower cutting die 318 . Cutting assembly 314 is operable to repeatedly shear like-sized sheets S from material M and to provide individual sheets S to stacking device 10 at the aforementioned first position.

[0034] In this respect, FIG. 5A shows material M being conveyed through guide rollers 312 and through cutting assembly 314 . Sheet stacking device 10 is oriented such that sheet supports 62 R, 62 L provide support for material M as it passes through cutting assembly 314 . Glide strips 168 R, 168 L on fins 166 R, 166 L of rotary elements 162 R, 162 L are disposed to provide support to the lateral edges of material M as it moves into stacking device 10 . FIG. 3 best illustrates material M being supported by glide strips 168 R, 168 L of right and left gripper/stacking assemblies 40 R, 40 L. Pinch rollers 312 cause material M to be conveyed to a position as illustrated in FIG. 5C . Gripper mechanisms 90 R, 90 L are initially in a first position as shown in FIG. 5A with linkage 134 R, 134 L in a first position wherein lower friction rollers 144 R, 144 L are disposed away from upper friction rollers 116 R, 116 L. The free end of material M is thus allowed to pass between friction rollers 116 R, 116 L and 144 R, 144 L. In this respect, the initial position of gripper mechanisms 90 R, 90 L is established by central processing unit 222 by controlling motors 76 R, 76 L which turns lead screws 74 R, 74 L and moves gripper mechanisms 90 R, 90 L to a predetermined position. In this respect, gripper mechanisms 90 R and 90 L are moved together by central processing unit 222 to side-by-side positions, as schematically illustrated in FIG. 5A . When material M has reached a predetermined length relative to cutting assembly 314 , rotary actuators 132 R, 132 L are energized by central processing unit 222 to cause linkage 134 R, 134 L to move second lever arms 138 R, 138 L to a second position, wherein lower friction rollers 144 R, 144 L press sheet material M against upper friction rollers 116 R, 116 L, as schematically illustrated in FIG. 5B . As will be appreciated, central processing unit 222 actuates rotary actuators 132 R, 132 L on both gripper mechanisms 90 R and 90 L. With material M supported along its lateral edges by glide strips 168 R, 168 L on rotary elements 162 R, 162 L, and with the leading edge of material M pinched between friction rollers 116 R, 116 L and 144 R, 144 L, cutting assembly 314 is energized, wherein upper cutting die 316 shears through material M severing it into a sheet S, as illustrated in FIG. 5C .

[0035] With sheet S severed from the generally continuous length of material M, central processing unit 222 causes gripper motors 76 R and 76 L to rotate lead screws 74 R, 74 L, to cause gripper mechanisms 90 R, 90 L to move away from cutting assembly 314 , wherein sheet S is slid along glide strips 168 R, 168 L of rotary elements 162 R,- 162 L. As illustrated in FIG. 5 D, sheet S is slid along to a position over stacking platform 202 . When sheet S reaches a predetermined position relative to platform 202 , as determined by central processing unit 222 by monitoring the position of gripper mechanisms 90 R, 90 L, rotary actuators 132 R, 132 L are energized by central processing unit 222 to cause linkage 134 R, 134 L to move to its first position, wherein lower friction rollers 144 R, 144 L move away from upper friction rollers 116 R, 116 L, thereby releasing the edge of sheet S. Sheet S is thus released in a position above stacking platform 202 . Central processing unit 222 causes stacker motors 188 R, 188 L to rotate rotary elements 162 R, 162 L ninety degrees (90°). In the embodiment shown, rotary element 162 R is rotated in a counter clockwise direction and rotary element 162 L is rotated in a clockwise direction. As a result of the rotation of rotary elements 162 R, 162 L, support for the edges of sheet S is removed, and sheet S is allowed to fall onto a stack on platform 202 . Rotation of rotary elements 162 R and 162 L by ninety degree (90°) positions another pair of glide strips 168 R, 168 L in horizontal relationship relative to each other to define a plane for supporting material M and a sheet S. Central processing unit 222 then causes gripper motors 76 R, 76 L to turn lead screws 74 R, 74 L in a direction to cause gripper mechanisms 90 R, 90 L to return to an initial position, as shown in FIGS. 5A, 5B , to receive the next sheet S to be cut from material M.

[0036] Referring now to FIG. 5 G, an operation for diverting sheets S from stacking platform 202 is illustrated. In some instances, it may be desirable not to stack a certain sheet S for some reason, such as by way of example and not limitation, a defect. In FIG. 5 G, scanners 226 are schematically illustrated and disposed above and below the path along which material M and sheet S will pass. Such scanners may be used to detect defects or imperfections in sheet S. In the event that a defect is detected, stacking device 10 is operable to divert such sheet to a divert bin, designated 372 . In this respect, the divert operation is essentially similar to the operation heretofore described and shown in FIGS. 5 A- 5 D. However, instead of gripper mechanisms 90 R, 90 L releasing the edge of sheet S above platform 202 , gripper mechanisms 90 R, 90 L pull sheet S to the end of stacking device 10 . Central processing unit 222 causes motors 126 R, 126 L to rotate upper friction rollers 116 R, 116 L so as to drive sheet S from sheet stacking device, as schematically illustrated in FIG. 5G . Specifically, in the embodiment shown, motors 126 R, 126 L cause belts 122 R, 122 L to rotate friction rollers 116 R, 116 L in a clockwise direction. The defective or undesirable sheet is thus ejected to a divert bin 372 by friction rollers 116 R, 116 L. Gripper mechanisms 90 R, 90 L are returned to their initial positions, as shown in FIG. 5A to receive the next sheet S to be cut from material M.

[0037] Referring now to FIGS. 6A and 6B , a method of adjusting sheet stacking device 10 to accommodate material M of different widths is shown. FIG. 6A shows right and left gripper/stacker assemblies 40 R, 40 L in a spaced-apart position to accommodate a sheet having a width WI. Sheet S is shown supported on glide strips 168 R, 168 L of rotary elements 162 R, 162 L above stacking platform 202 (shown in phantom). The relative positions of gripper/stacker assemblies 40 R, 40 L may be adjusted to accommodate a sheet having a width W 2 , as shown in FIG. 6 B, by using hand wheel 36 to rotate lead screw 34 . Carriage mounts 54 R, 54 L on platform 42 R, 42 L, respectively, are operable to cause the same to move in opposite directions upon rotation of lead screw 34 in a manner as is conventionally known. Thus, rotating hand wheel 36 in a predetermined direction, will cause right and left gripper/stacker assemblies 40 R, 40 L to accommodate material M and sheet S of desired width.

[0038] As will also be appreciated, the operation of sheet stacking device 10 may be adjusted to stack longer or shorter sheets by merely reprogramming central processing unit 222 to change the initial position, travel distance and release point of gripper mechanisms 90 R, 90 L.

[0039] The present invention thus provides a sheet stacking device 10 operable to accommodate sheet material of differing lengths and widths, and a sheet stacking device 10 that is able to automatically stack sheet material at a predetermined location and automatically divert undesirable sheets from the stacking location.

[0040] The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purposes of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.