US20060263192A1 - Method and apparatus for stacking discrete planar objects - Google Patents

Abstract

A system for forming a plurality of discrete objects into a stack is disclosed which system includes a frame having a top, a bottom and sides; a conveyor associated with the frame and having an end edge for dispensing discrete objects, a first support mounted on the frame near the end edge for receiving objects from the end edge and having an opening with a width smaller than the width of the objects, a first actuator operably connected to the first support for moving the first support between first and second positions relative to the end edge; a second actuator operably connected to the first support for moving the first support between upper and lower positions relative to the frame; a second support mounted on the frame beneath the first support having a width less than the width of the opening in the first support; a third actuator operatively connected to the second support for moving the second support between high and low positions, the second support high position being higher than the first support lower position; a third support mounted on the frame at a position higher than the second support low position and having an opening wider than the width of the second support; a fourth actuator operatively connected to the third support for moving the third support between a first position beneath the first support and a second position; a sensor for determining the number of discrete objects in a stack, the sensor being operatively coupled to the to the third actuator; and a controller for controlling the first, second, third and fourth actuators. A method of using the system is also disclosed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM TO PRIORITY
• The present application claims the benefit of U.S. provisional patent application Ser. No. 60/290,342, filed May 14, 2001, the disclosure of which is incorporated by reference.
FIELD OF THE INVENTION
• The present invention is directed to a method and apparatus for forming one or more rows of discrete, planar objects, into one or more stacks, and more specifically, toward a method and apparatus for continuously forming at least one moving stream of disk-like objects, such as frozen hamburger patties, into one or more stacks and moving the finished stacks to a station for further processing.
BACKGROUND OF THE INVENTION
• Frozen hamburgers, chicken patties, sausage patties, and other disk-like food products typically are prepared by a manufacturer on one piece of equipment and then fed into a freezer. After leaving the freezer, they are screened by a metal detector, which causes contaminated patties to be ejected, and then conveyed to a stacker. Because the stacks formed by some stackers can vary in height, and because the number of stacks formed simultaneously by a stacker may be greater than the number of stacks that will fit in a case, the finished stacks are often manually removed from the stacker and loaded into cases. This manual loading step is labor-intensive, and, due to the presence of a human element, highly variable.
• One known prior art patty stacking machine is disclosed in U.S. Pat. No. 6,052,969, assigned to the assignee of the present application, which is hereby incorporated by reference. That machine includes a conveyor for moving patties in a first direction and dropping them into helical coil. The patties fall between the loops of the coil, and as the coil is rotated, new loops are presented for receiving additional patties. The rotation of the coil advances the patties into a holder, and when the holder is filled, a mechanical jaw grips the stack and moves it to a packing station from which it is loaded into a packing machine. This machine serves its intended purpose adequately, but suffers from various problems such as being bulky. In addition, if patties are not accurately aligned with loops of the coil, they may hit the coil instead of falling between the loops which leads to stacks of varying heights and to product waste.
• To maximize efficiency, it is preferable to have the entire process of stacking and packing patties automated, and to do so in a manner that allows for continuous production and that minimizes the likelihood of product jams. Furthermore, it is desirable that a patty stacking machine can easily be retrofitted to the end of a patty processing production line and that the machine be sufficiently compact so as not to interfere with other existing parts of the processing machinery.
SUMMARY OF THE INVENTION
• These and other problems are addressed by the present invention which comprises a method and apparatus for receiving a plurality of disk-like objects, such as frozen hamburger patties, forming them into stacks, and transferring the stacks to a holding station from which they are packed into cartons. While the application is particularly well suited for use with frozen hamburger and related food patties, it may easily be adapted to process other food and non-food objects. Furthermore, nearly any symmetrical object can be processed according to the invention, and even non-symmetrical planar objects may be processed if they are properly oriented. Thus, while the invention will generally be described in the context of frozen, disk-like food patties, its application is in no manner limited to use with this type of product.
• In a preferred embodiment, the invention comprises a continuous conveyor belt that is either part of a patty processing line or that is adjacent to a conveyor leading from a patty processing system and that receives patties therefrom. The subject invention can be used to stack a single row of patties, but for reasons of speed and efficiency, patties are usually arranged on a conveyor in multiple rows, frequently four, five or six rows. Therefore, the preferred embodiment of the invention is designed to process multiple rows by simultaneously forming multiple stacks and then transferring those stacks to a holding location, while another portion of the stacker continues to receive patties from the conveyor. In this manner, the stacker can process patties continuously, and there is no need to stop the conveyor to allow the stacks to be transferred from the stacker to the holding location.
• The conveyor has an end edge over which the patties of each row fall onto a first holder, sometimes referred to as an upper support or shelf. The upper support preferably comprises a plurality of pairs of parallel pins that extend from a support toward the end edge of the conveyor so that individual patties in a given row drop one at a time off the end of the conveyor onto a pair of pins. Hereafter, the processing of a single stack of patties will sometimes be discussed, it being understood that other stacks are being formed substantially simultaneously on adjacent pairs of pins. The upper support is lowered as each new patty falls onto it in order to keep the top of the stack on the shelf about the same distance beneath the end edge of the conveyor. The height of the top of the stack varies somewhat during processing, but it preferably is maintained within a fairly narrow range to ensure that the patties drop consistently and form stacks. In the preferred embodiment, a counter adjacent the conveyor is used to count patties in a row just before they fall onto the upper support, and a cam is used to lower the shelf at a known rate.
• A second holder comprising a plurality of fingers is positioned beneath the upper support, with each finger aligned with the opening between a pair of upper support pins. As the upper support drops, the pins eventually pass to each side of one of the fingers, and as the upper support drops further, the bottom of the stack contacts a finger on the second holder and is supported thereby. When the stack is completely supported by the fingers, the upper support pivots away from the stream of falling patties and returns to its starting position while the second holder continues to drop, keeping the top of the stack at a generally constant height. A transfer device is mounted beneath the second support, which device includes a plurality of openings aligned with each of the fingers on the second support. When a stack contains the correct number of patties, or is otherwise determined to be complete, the second holder drops so that the fingers pass through the openings in the transfer device, leaving the stacks supported by the transfer device. Preferably, as soon as the second shelf begins to drop, the end of the conveyor is moved to lengthen the conveyor and create a gap in the flow of patties; this delays the release of the next group of patties and allows the upper shelf to move into position to catch additional patties. The upper support thus supports a next group of falling patties, while the following processing steps are carried out on the first stack.
• Once the stacks are supported on the transfer device and the fingers of the second support are located beneath the transfer device, the transfer device secures the stacks and moves sideways to transfer the stacks to a holder. As the transfer device is moving the stacks to the holder, the second support is free to return to its starting position beneath the upper support. Once the transfer of patties is complete, the transfer mechanism returns to its starting location beneath the second support, and the process is repeated.
• It is therefore a principal object of the present invention to provide a stacking machine for forming a plurality of objects into one or more stacks.
• It is another object of the invention to provide a method of forming a plurality of objects into one or more stacks of a fixed size in a continuous manner.
• It is a further object of the present invention to provide a stacking machine having a transfer mechanism for transferring a first set of finished stacks to a holding area while a second set of stacks is being formed.
• It is yet another object of the present invention to provide a stacking machine having first and second supports for supporting one or more stacks of planar objects.
• It is yet a further object of the present invention to provide a stacking machine that is compact and easily retrofittable to existing equipment.
• It is still another object of the present invention to provide a stacking machine for forming one or more stacks of planar disk-like objects that is reliable and not subject to jamming.
• In furtherance of these objects, a method of forming a stream of discrete objects into a stack is disclosed that includes the steps of providing a frame having a top, a bottom and sides and providing a plurality of discrete objects each having a width. A first support is provided on the frame that has an opening smaller than the width of said objects, which support is movable vertically between upper and lower positions and movable horizontally between engaged and disengaged positions. The first support is held in said upper and engaged positions while said discrete objects are dropped onto said first support to form a stack having a top and a bottom. The first support is moved toward the lower position to maintain the top of said stack at a first level relative to said frame. A second support is provided beneath said first support which second support has a width less than the opening in said first support, and the second support is movable between a high position above said lower position and a low position. The first support is lowered toward the second support until said second support passes through said opening in said first support and contacts the bottom of said stack. Then the first support is moved to said disengaged position. The second support is lowered to maintain the top of said stack at said first level. A third support is provided that has an opening and is translatable between a first position beneath said second support and a second position. A sensor senses for the occurrence of a stack finished condition, and when that condition is detected, the second support is lowered until it passes thought the opening in said third support and said third support contacts the stack bottom.
• Another aspect of the invention comprises a system for forming a plurality of discrete objects into a stack that includes a frame having a top, a bottom and sides and a conveyor associated with the frame that has an end edge for dispensing discrete objects. A first support is mounted on the frame near the end edge for receiving objects from the end edge and has an opening with a width smaller than the width of the objects. A first actuator is operably connected to the first support for moving the first support between first and second positions relative to the end edge and a second actuator is operably connected to the first support for moving the first support between upper and lower positions relative to the frame. A second support is mounted on the frame beneath the first support and has a width less than the width of the opening in the first support. A third actuator is operatively connected to the second support for moving the second support between high and low positions where the second support high position is higher than the first support lower position. A third support is mounted on the frame at a position higher than the second support low position, and the third support has an opening wider than the width of the second support. A fourth actuator is operatively connected to the third support for moving the third support between a first position beneath the first support and a second position, and a sensor is provided for determining the number of discrete objects in a stack, where the sensor is operatively coupled to the to the third actuator. A controller controls the first, second, third and fourth actuators.
• Another aspect of the invention comprises a method of forming a stream of discrete disk-like objects into a stack that involves providing a frame having a top, a bottom and sides supporting a conveyor having an end edge. A plurality of discrete disk-like objects, each having a diameter, are placed on the conveyor. A first support is provided on the frame adjacent the end edge, which first support includes first and second spaced apart pins separated by a distance less than the diameter of the objects. The first support is movable vertically between upper and lower positions and pivotable between engaged and disengaged positions. The first support is held in the upper position and in the engaged position and the conveyor is operated to cause the objects to fall over the end edge of the conveyor and onto the first support to form a stack having a top and a bottom. A counter is incremented each time one of the disk-like objects passes a given location on the conveyor, and the first support is toward the lower position each time the counter is incremented. A second support is mounted beneath the first support that has a width less than the distance between the pins, the second support being movable between a high position above the lower position and a low position. The first support is lowered over the second support until the second support passes between the pins and contacts the bottom of the stack, then the first support is pivoted the disengaged position. The second support is lowered each time the counter is incremented when the stack is in contact with the second support. A third support is provided that has an opening wider than the second support and that is translatable between a first position beneath the second support and a second position. When the counter reaches a predetermined count, the second support is lowered until it passes through the opening in the third support and the third support contacts the stack bottom. The first support is moved to the upper position and the engaged position after the top of the stack drops beneath the lower position, and the third support is moved to the second position and releases the stack into a stack holder after the third support contacts the stack bottom. Next, the second support is moved to the high position after the third support moves from the third support first position, and the third support is then returned to the third support first position after the stack has been released into the stack holder.
• An additional aspect of the invention is a method of forming a plurality of rows of discrete objects into a plurality of stacks that involves providing a frame having a top, a bottom and sides and a plurality of discrete objects, each having a width, arranged in rows. A first support is provided on the frame that has a plurality of spaced apart openings smaller than the width of the objects, the first support being movable vertically between upper and lower positions and movable horizontally between engaged and disengaged positions where each of the plurality of openings is aligned with one of the plurality of rows. The first support is held in the upper and engaged positions and the discrete objects are dropped onto the first support over the plurality of openings to form a plurality of stacks each having a top and a bottom. Next, the first support is moved toward the lower position to maintain the tops of the stacks at a first level relative to the frame. A second support is provided beneath the first support comprising a plurality of fingers, each finger being aligned with and having a width less than the width of the openings in the first support. The second support is movable between a high position above the lower position and a low position. The first support is lowered over the second support until the plurality of fingers on the second support pass through the openings in the first support and contact the bottoms of the stacks. The first support is moved to the disengaged position and the second support is lowered to maintain the top of the stacks at the first level. A third support having a plurality of openings wider than and aligned with the plurality of fingers and translatable between a first position beneath the second support and a second position is provided. A sensor senses for the occurrence of a stack finished condition, and, when the condition is detected, the second support is lowered until the fingers pass thought the openings in the third support and the third support contacts the bottoms of the stacks. The stacks on the third support are covered and the third support is pivoted to invert the stacks on the third support while being translated toward a discharge location.
• A further aspect of the invention comprises a system for forming a plurality of discrete objects arranged in rows into a plurality of stacks that includes a frame having a top and a bottom and a first side having an inner wall and a second side having an inner wall facing the first side inner wall. The first side inner wall and the second side inner wall each include a guide track. A first cam is mounted on the frame as is a drive for rotating the first cam and the second cam. A conveyor is associated with the frame and has an end edge for dispensing rows of discrete objects. A first support is mounted on the frame near the end edge, for receiving objects from the end edge, and has a plurality of rods spaced by a distance less than the width of the objects. A guide wheel is received in each of the guides on the frame first wall and the frame second wall, and a cam follower movable into engagement with the first cam is attached to the first support. A first actuator is operably connected to the first support for moving the first support between first and second positions relative to the end edge. A second actuator is operably connected to the first support for moving the first support between upper and lower positions. A second support is mounted on the frame beneath the first support and comprises a plurality of fingers each having a width less than the distance between the first support rods. A third actuator is operatively connected to the second support for moving the second support between high and low positions, the second support high position being higher than the first support lower position. A third support is mounted on the frame at a position higher than the second support low position and comprises a frame portion and a tray portion, the tray portion including a bottom wall having a plurality of openings wider than the width of the fingers. A fourth actuator is operatively connected to the third support for moving the third support between a first position beneath the second support and a second position, and a sensor is provided for counting the number of objects passing a point on the conveyor, the sensor being operatively connected to the drive for rotating the first cam and the second cam. A controller is also provided for controlling the first, second, third and fourth actuators and the drive.
• Another aspect of the invention comprises a system for forming a plurality of discrete objects into a stack comprising a frame having a top, a bottom and sides, a conveyor associated with the frame and having an end edge for dispensing discrete objects, and a receiver mounted on the frame near the end edge for receiving objects from the end edge, the receiver having a first object-engaging portion adjacent the end edge and a second object-engaging portion located beneath the conveyor.
• A further object of the invention comprises a stacker for forming a plurality of objects into stacks comprising a frame and a first support mounted on the frame having an opening with a width smaller than the width of the objects and being shiftable between an upper position and a lower position relative to the frame. A second support is also mounted on the frame beneath the first support and is aligned with the opening in the first support. The second support has a width less than the width of the opening in the first support and is shiftable between a first position above the first support lower position and a second position so that shifting the first support from the upper position to the lower position while the second support is in the first position causes the second support to pass through the opening.
• An additional aspect of the invention comprises a transfer mechanism for receiving a stack of objects from a stacker and moving the stack to a location away from the stacker that includes a support having an opening wider than a stack-supporting element of the stacker, a wall normal to the support for engaging the side of the stack and a cover shiftable between a first position adjacent the top of the stack and a second position. The transfer mechanism also includes an actuating mechanism for moving the cover to the first position and the support toward the location while inverting the support to bring the stack bottom into a position above the stack top.
• An additional aspect of the invention comprises a system for forming a plurality of discrete objects into a stack comprising a frame having a top, a bottom and sides and a conveyor associated with the frame, which conveyor has a generally horizontal surface movable in a first direction for moving a plurality of objects in the first direction toward and over an end edge. A movable receiver is mounted on the frame near the end edge for receiving objects from the end edge and is angled with respect to the surface, so that objects supported on the movable receiver move in a direction opposite to the first direction.
BRIEF DESCRIPTION OF THE DRAWINGS
• These and other objects will be better understood after a reading and understanding of the following detailed description of a preferred embodiment of the invention together with the following drawings of which:
• FIG. 1 is a perspective view of a stacking device according to the present invention which device includes a conveyor, an upper support, a lower support and a transfer device.
• FIG. 2 is an end elevational view of the stacking device ofFIG. 1.
• FIG. 3 is an assembly drawing of the stacking device ofFIG. 1.
• FIG. 4 is a perspective view of the upper support and lower support ofFIG. 1.
• FIG. 5 is a perspective view of the upper support ofFIG. 1.
• FIG. 6 is a perspective view of the lower support ofFIG. 1.
• FIG. 7 is a perspective view of the transfer device ofFIG. 1.
• FIG. 8 is a side elevational view of the transfer device ofFIG. 1.
• FIG. 9 is a side elevational view of the stacking device ofFIG. 1 showing a stack of objects that has just been transferred from the second support to the transfer device.
• FIG. 10 is a side elevational view of the stacking device ofFIG. 1 showing the transfer device in a position to release a stack at a discharge location while a second stack of objects on the upper support moves toward the lower support.
• FIG. 11 is a side elevational view of the stacking device ofFIG. 1 showing a stack of objects supported on the lower support moving toward the transfer device which has returned to its starting location beneath the second support.
• FIG. 12 is a side elevational view of the stacking device ofFIG. 1 showing the transfer device rotating and translating a stack of objects toward a discharge location while the upper support catches objects dropping off the conveyor.
DETAILED DESCRIPTION OF THE INVENTION
• Referring now to the drawings, wherein the showings are for purposes of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting same, a general overview of the present device can be gained from viewingFIGS. 1 and 3 which show a stacking device designated generally by the numeral10, with anadjacent conveyor12 having anend edge14. A plurality of disk-shapedobjects16, in this case, frozen hamburger patties, are arranged in rows on theconveyor12 extending in the direction of movement of the conveyor. Asconveyor12 moves, it causespatties16 to be advanced so as eventually to drop offend edge14 onto anupper support18, as best shown inFIG. 5, to formstacks20 of patties thereon as best shown inFIG. 11.Upper support18 is downwardly movable in order to keep the top ofstacks20 at a generally constant level with respect to endedge14 of theconveyor12. Asupper support18 descends, it transfers thestacks16 to alower support22, as best shown inFIG. 3, and moves laterally out of the falling streams of patties so thatfurther patties16 from theconveyor12 fall directly onto thestacks20 supported bylower support22. Thelower support22 is downwardly movable and continues to drop until asensor226 detects that thestacks20 have reached their final size. At this point,lower support22 transfers thestacks20 to astack transfer mechanism24 that moves thestacks20 laterally away from theconveyor12 toward a discharge location. Additional fallingpatties16 are caught byupper support18 orlower support22 as discussed above, andtransfer device24 returns to its starting position beneath theupper support18 and theconveyor12 before a subsequent set of stacks ofpatties20 is complete.Controller23, as best shown inFIG. 1, controls the operation of the actuators and drives described herein, and is preferably a computer or PLC that controls the speed of the various drives and the operation of the actuators to carry out the steps of the process described herein. This arrangement allows for a continuous processing ofpatties16 arriving at theend edge14 of aconveyor12 without the need to stop the conveyor each time a stack is completed.
• Stacker10 is installed on a fixedsupport26, such as a factory floor, and includes a fixedframe portion28 fixed with respect to support26 and amovable frame portion30 that moves with respect to the fixedframe portion24, which fixedframe portion28 andmovable frame portion30 for a frame for the stacker.Movable frame portion30 includes foursupport wheels32 resting on fourplatforms34, which in turn rest on the fixedsupport26. Amotor36 is operable connected to ashaft38 which is rotatably supported by twobearings40 that are supported by bearingsupports42, one of which is shown inFIG. 1, mounted onfloor26. Twoarms44 are fixed toshaft38 and extend radially therefrom so that the ends ofarms44 describe an arc of a circle as theshaft38 rotates.Tie rods46 connectarms44 tomovable frame30 so that, asmotor36 turnsshaft42 in a first direction, themovable frame portion30 is pulled alongplatforms34 towardmotor36, and asmotor36 turns in a second direction, themovable frame portion30 is pushed alongplatforms34 away frommotor36. Theroller48 supporting theend edge14 of the conveyor12 (FIG. 3) is supported on themovable frame portion30 while other portions ofconveyor12 are supported by the fixedframe portion28. Therefore, theconveyor12 includes a slack take-upmechanism50, shown inFIGS. 9-12, which allows the effective length of theconveyor12 to increase and decrease as themovable frame portion30 moves away from and back towards the fixedframe portion28. When the effective length of theconveyor12 is increased in this manner, the spacing is increased between rows ofpatties16 arriving atend edge14, and this extra spacing or gap allows theupper support18 to pivot back into the flow of falling patties to start a new stack.
• Movable frame portion30 comprises a firstvertical plate member52 having aninner wall54 and anouter wall56, and a secondvertical plate member58 having aninner wall60 and anouter wall62. Aguide64 is formed oninner wall54 of the firstvertical plate member52 by a pair of spacedrails66, while an upper guide is formed in the secondvertical plate58 by anupper slot70, and a lower guide is formed in secondvertical plate58 by alower slot74.Rods76 and77 extend between the inner walls of the first and second vertical plates to maintain their spacing.
• With reference toFIGS. 3 and 5,upper support18 comprises acarrier78 including afirst side plate80 having aninner side82 and anarcuate slot84, and asecond side plate86 having aninner side88, anouter side90 and anarcuate slot92 aligned witharcuate slot84 in thefirst side plate80. Thesecond side plate86 is parallel to thefirst side plate80 and spaced therefrom by connectingrod94.Carrier78 supports a pivotingmember96 comprising a first L-shapedmember98 having anouter wall100 with a pin102 (seen inFIG. 3) projecting therefrom and aninner wall104, and a second L-shapedmember106 having aninner wall108 facinginner wall104 of the first L-shapedmember98 and anouter wall110 from which apin112 projects. Theouter wall100 of first L-shapedmember98 overlies theinner side82 offirst side plate80, withpin102 received inarcuate slot84, and extends beyond thefirst side plate80. Theouter wall110 of the second L-shapedmember106 overlies theinner side88 ofsecond side plate86 withpin112 received inarcuate slot92 of thesecond side plate16. Afirst rod114 extends between the middle portions of theinner walls104,108 of the first and second L-shapedmembers98 and106, respectively, and asecond rod116 extends between the portions of the first and second L-shapedmembers98 and106, respectively, that project beyond thefirst side plate80 andsecond side plate86. A plurality ofpins118 arranged inpairs120 spaced apart by a given distance extend radially fromsecond rod116 as best shown inFIG. 5. First L-shapedmember98 is pivotally connected to theinner wall82 offirst side plate80 at apivot point122, while second L-shapedmember106 is pivotally connected to theinner wall108 of thesecond side plate86 at apivot point124. Anactuator126, preferably a pneumatically actuated cylinder, is connected betweenfirst side plate80 and anend128 of first L-shapedmember98 on the opposite side ofpivot point122 fromrod114, which actuator126 causes first L-shapedmember98, and hencecarrier78, to pivot about pivot points122 and124, whilepins102 and112 inarcuate slots84,92 guide the movement of the pivotingmember96 with respect to thecarrier78.Guide wheels130 are mounted on the outer walls of thefirst side plate80 andsecond side plate86 which wheels are received in theguides64,70 of thevertical plates52 and58 of themovable frame portion30. Acam follower132 also extends from theouter side90 of thesecond side plate86. Plates133 attached torod94 form a backstop against which patties impact as they form stacks on thepairs120 ofpins118.
• FIG. 6 illustrateslower support22, which includes a first side plate1134 having aninner side136 and anouter side138, and asecond side plate140 having aninner side142 and anouter side144. Astrut146 connects the inner sides of the first andsecond side plates134 and140, respectively, and ahexagonal rod148 extends between the inner sides of the first and second plates parallel to strut146.Guide wheels150 are attached toouter sides138 and144 offirst side plate134 andsecond side plate140, respectively, and theouter side144 ofsecond side plate140 further includes acam follower152. A plurality offingers154 are attached tohexagonal rod148, each of which includes at least oneplanar surface156.
• Transfer mechanism24, best shown inFIGS. 7 and 8, comprises a first L-shapedplate member158 and asecond plate member160 parallel to and spaced fromfirst plate member158 by arod162 extending between end portions ofplate members158 and160 whichrod162 is supported at either end bybearings164. Atray assembly166 includes twoside plates168 connected by a connectingrod170. A plurality oftrays172, each having abottom wall174 having aslot176 andside walls178, are pivotally attached to platemembers158,160. Ahexagonal rod180 is rotatably attached betweenside plates168, and a plurality of L-shaped coveringfingers182 are attached thereto.Actuator184, connected between theplate member158 andhexagonal rod180, rotates thehexagonal rod180 to move the L-shapedfingers182 between a first position where a portion of the L-shapedfingers182 overlies thetrays172 and a second position, as best shown inFIG. 7, where no portion of the L-shapedfingers182 overlies thetrays172.
• As best shown inFIG. 7, abelt drive186 is located in housing188 (seen inFIG. 2) attached toplate member160, and includes a firstflanged wheel190 mounted on the outer side ofplate member160, which flanged wheel is coupled to amember192 having an extendinglever arm193 connected to anactuator194. A secondflanged wheel196 is operably coupled to connectingrod170 and rotationally coupled to firstflanged wheel190 by abelt198. When actuator194 presses againstlever arm164, it rotates the firstflanged wheel180 which rotation movesbelt198 and causes the secondflanged wheel196 and hence connectingrod170 to rotate; this tiltstray assembly166 with respect toplates158,160.Actuator200 attached tosecond plate member160 causes theentire tray assembly166 to pivot about the axis ofrod162, whileactuator202 moves thetray assembly166 away from theconveyor12 toward a stack discharge location and return thetray assembly166 to its starting position after the patties have been discharged.
• Referring now toFIG. 1, amotor support204 is mounted on theouter wall62 ofvertical support plate58, and amotor206 is mounted on the support. Themotor206 turns a shaft connected tovertical plate58 and two cams—aninner cam208adjacent plate58 and anouter cam210 between the inner cam and themotor206.
• The mounting ofupper support18 between firstvertical plate52 and secondvertical plate58 is apparent inFIG. 3 which illustrates theguide wheels130 of second L-shapedmember106 received betweenrails66 ofguide64 and guidewheels130 of first L-shapedmember98 extending towardupper slot70 of secondvertical plate member58.Cam follower132 rides along the outer surface ofinner cam208 and the downward movement of theupper support18 is limited by the bottom end ofslot70. The mechanism for holding theupper support18 againstcam208 is best seen inFIG. 3, and comprises anactuator212 mounted on theouter wall56 of firstvertical plate52 which moves alever arm214 attached to arotatable shaft216 mounted between firstvertical plate52, and secondvertical plate58 at an upper edge thereof. Fromshaft216 extend first and secondangled arms218 which overlie connectingrod94 of the upper support. By movinglever arm214,actuator212 raises and lowers angledarms218 to press down upon the upper support or to move thearms218 away from the upper support.
• Lower support22, as best seen inFIG. 3, is mounted between firstvertical plate52 and secondvertical plate58 with theguide wheels150 of theouter sides138 offirst plate134 received betweenrails66 ofguide64 and the set ofguide wheels150 on theouter side144 ofsecond plate140 extending throughlower slot74 of secondvertical plate58.Cam follower152 is biased upwardly againstouter cam210 by a mechanism that includes anactuator220 mounted on the outer wall of56 of the firstvertical plate52 connected to alever arm222 which in turn is connected to ashaft224 rotatably mounted between the first and secondvertical plates52,58 on the edge of the plates beneath theconveyor12. Twoarms223connect shaft224 tofirst side plate134 andsecond side plate140 oflower support22 so that, when actuator220 moveslever arm222 and turnsshaft224 in a first direction,cam follower152 of thelower support22 is pressed upwardly againstouter cam210 and pulled away fromouter cam210 whenshaft224 is turned in the opposite direction.
• The operation of the stacker will now be described with reference primarily to FIGS.9 though12 which show the stacker in various stages of forming a plurality of hamburger patties into stacks and transferring those stacks from a stacking location toward a discharge location. Beginning withFIG. 9,patties16 move alongconveyor12 and fall over theend edge14 of the conveyor ontofingers118 ofupper support18.FIG. 9 shows onepatty16 already supported by thefingers118 with another about to fall onto the first patty to begin to form a stack. Beneficially, theupper support18 and thelower support22 are located generally beneath theend edge14 of theconveyor12, and thus the stacks that form on the upper and lower supports are also formed generally beneath theconveyor12. This formation of stacks beneath the end of the conveyor advantageously contributes to the compact size of this stacking device because the stacks are formed against the direction of movement ofconveyor12.Actuator212 rotateslever arm214 to turnshaft216 to pressarms218 against the upper support to hold the uppersupport cam follower132 againstinner cam208, and, as the radius ofcam132 decreases while it rotates counterclockwise as viewed inFIGS. 9-12, theupper support18 moves downwardly toward thelower support22. The rotation of theinner cam208 is based on the rate that the stack is forming as detected byoptical detector226, best shown inFIG. 1, so that the top ofstack20 remains approximately the same distance belowconveyor end edge14 and ensures that each patty drops a similar distance in a similar manner to form consistent stacks.
• FIG. 10 shows stack20 onfingers118 has grown in size and moved closer to thefinger elements154 oflower support22. As theupper support18 continues its descent, the pair offingers118 of theupper support18 supporting the stack will pass to either side of one of thefingers154 of thelower support22 so that, as theupper support18 continues to drop past thelower support22, thestack16 will be deposited on thelower support22, andactuator126 will pivot theupper support18 away from theconveyor12 so thatadditional patties16 will fall onto the stack on thelower support22.
• InFIG. 11, the stack has grown to its finished size, at whichpoint actuator220pivots shaft224 to drop thelower support22 to causelower support finger154 to pass through theslot176 inbottom wall174 of one of thetrays172 of thetransfer mechanism24, to leave the stack supported on thetransfer mechanism24. In this figure too, thepins118 of theupper support18 can be seen moving back towardconveyor12 to catch the next patty falling therefrom in order to start a second stack rather than allowing it to fall on to the completed stack on the transfer mechanism. At this point,motor36 rotatesshaft38 to pullmovable frame30 away from fixedframe28 to lengthen the conveyor (effectively movingend edge14 away from the next row of patties) and delay the passage of additional patties over end edge. This second stack will be processed in the same manner as was the first stack.
• FIG. 12 shows thetransfer mechanism24 has rotated and translated away from theconveyor12 toward adischarge location228 on which the stacks will be deposited. To accomplish this movement,actuator200 first pulls and then pushes againstlever arm201 to rotatelever arm201 in a counterclockwise direction as seen inFIG. 8 which, through a gearing mechanism, rotatestray assembly166 to the inverted orientation seen inFIG. 12.Actuator194 presses againstlever arm193 to pivot thetray assembly166 relative to thetransfer mechanism wall158 to fully invert thestack20 of patties and deposit them ontoholder228, which holder has a slot in a bottom support wall to allow coveringfingers182 to pass therethrough when actuator184 moves the coveringfingers182 away from the stack prior to returning to its starting location beneath theconveyor12 in time to receive the next stack of patties from thelower support22.
• During the foregoing process, drive36 rotatesshaft38 to movemovable frame30 alongsupports34 on fixedframe28 to position themovable frame portion30 and hence thetransfer mechanism24 for optimal operation. As seen inFIG. 11, wherestack20 is transferred from thelower support22 to thetransfer mechanism24,movable frame portion30 is closest to fixedframe portion30, andwheels32 are positioned near the right edges ofsupports34 as viewed inFIGS. 9-12.FIG. 9 shows thetransfer mechanism24 has moved to a point approximately halfway between theconveyor12 anddischarge location228, andmovable frame portion30 has also moved in this direction as can be seen from the positions ofwheels32 on the supports. InFIG. 12,transfer mechanism24 has reacheddischarge location228, and themovable frame portion30 has also moved closer to the discharge location as can be seen from the positions ofwheels32 on thesupports34. As discussed above, this motion provides for lengthening and shortening the conveyor as needed to vary the spacing between advancing rows of patties to give the upper support time to move into a stream of falling patties.
• The subject invention has been described above in terms of a preferred embodiment. However, numerous obvious additions and modifications will become apparent to those skilled in the art upon a reading of the foregoing description. It is intended that all such additions and modifications form a part of the present invention to the extent that fall within the scope of the several claims appended hereto.

Claims (8)

1-42. (canceled)

43. A stacker for forming a plurality of objects into stacks comprising:

a frame;

a first support mounted on said frame having an opening with a width smaller than the width of said objects and being shiftable between an upper position and a lower position relative to said frame; and

a second support mounted on said frame beneath said first support, said second support being aligned with said opening in said first support, having a width less than the width of said opening in said first support, and being shiftable between a first position above said first support lower position and a second position;

whereby shifting said first support from said upper position to said lower position while said second support is in said first position causes said second support to pass through said opening.

44. The stacker ofclaim 43 further including a third support having an opening aligned with said second support and wider that said second support mounted at a location above said second support second position.

45. The stacker ofclaim 43 further including a third support having an opening wider that said second support mounted at a location above said second support second position whereby said second support passes through said third support opening when said second support moves from said first position to said second position.

46. The stacker ofclaim 45 wherein said third support is movable between a first location beneath said second support and a second position away from said second support.

47. The stacker ofclaim 43 wherein said first support comprises a pair of fingers and said opening comprises the space between said fingers.

48. The stacker ofclaim 47 wherein said second support comprises a finger having a width less than the separation between said first support pair of fingers.

49-53. (canceled)

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