Abstract:
An apparatus for stacking horizontally conveyed individual flats into vertically extending stacks including a stacking housing with an upper station for receiving the flats singly and releasing them downwardly into an intermediate station wherein multiple flats are accumulated and the accumulated grouping is then released downwardly to form an overall vertically extending stack of twenty flats or more for exit conveying. A control system is further disclosed including control plates, link arms and retaining/releasing arms for controlling downward movement of the flats within the stacking housing.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention deals with the field of automated conveying systems for handling of large horizontally extending members which are designed to hold a plurality of individual discreet items. An example of such an item is a flat which is designed to hold a plurality of eggs such as a five by five or six by six array thereof. These flats nest within one another and need to be stacked and destacked for various stages of operation such as cleaning, sanitizing, drying and handling to facilitate reuse. The present invention provides a unique apparatus for high speed stacking of individual flats such as would be encountered immediately after washing of the individual flats. The flats can be stacked vertically to a height of 20, 30 or more and then can proceed to a drying apparatus such as a spin dryer for simultaneous drying thereof. The washing, however, needs to be done individually and for this reason the flats need to be separated and conveyed through the washing station individually in an unstacked position to facilitate effective washing. The present invention provides a unique apparatus solely for the purpose of taking these single flats oriented horizontally and traveling upon a conveyor and stacking thereof vertically and again positioning them on a conveyor for transport to a drying station. 
     2. Description of the Prior Art 
     Numerous devices have been used for the purpose of stacking, unstacking or other handling of flats or other horizontally oriented members which are preferably nestable and can receive a plurality of discreet items therein such as eggs or the like. Examples of patents which have been granted on such apparatus include U.S. Pat. No. 2,915,308 patented Dec. 1, 1959 to J. C. Matzen on “Automatic Feeding Machines”; and U.S. Pat. No. 3,053,529 patented Sep. 11, 1962 to M. B. Dunn and assigned to Memco Machinery Corporation on a “Blank Feeding Apparatus For Box Erecting Machine”; and U.S. Pat. No. 3,130,967 patented Apr. 28, 1964 to J. Le Brell and assigned to Alton Box Board Company on a “Hopper Feed For Carton Blanks”; and U.S. Pat. No. 3,718,217 patented Feb. 27, 1973 to A. R. Stobb et al on an “Apparatus For Feeding Signatures”; and U.S. Pat. No. 3,724,640 patented Apr. 3, 1973 to H. Rapparlie and assigned to Licentia Patent-Verwaltungs-GmbH on a “Device For Forming Stacks From A Flow Of Consecutively Furnished Flat Items”; and U.S. Pat. No. 3,774,783 patented Nov. 27, 1973 to A. H. Miller et al and assigned to Libbey-Owens-Ford Company on an “Apparatus For Handling Sheet Material”; and U.S. Pat. No. 3,792,784 patented Feb. 19, 1974 to J. H. Mosterd on a “Device For Handling Egg Trays”; and U.S. Pat. No. 3,945,633 patented Mar. 23, 1976 to A. A. Knopp and assigned to Harris-Intertype Corporation on a “Hopper Loader”; and U.S. Pat. No. 4,164,296 patented Aug. 14, 1979 to C. I. Trees and assigned to The Lodge &amp; Shipley Company on an “Apparatus For Transferring And Rotating Articles”; and U.S. Pat. No. 4,293,272 patented Oct. 6, 1981 to A. Jellema and assigned to Staalkat B. V. on a “Method And Apparatus For Denesting A Plurality of Containers Filled With Articles”; and U.S. Pat. No. 4,298,156 patented Nov. 3, 1981 to R. F. Reifers et al and assigned to Diamond International Corporation on “Nestable And Denestable Molded Egg Cartons”; and U.S. Pat. No. 4,302,142 patented Nov. 24, 1981 to H. Y. Kuhl et al and assigned to Kuhl Corporation on an “Apparatus For Automatically Loading Eggs Directly From Stacks Of Egg-Filled Flats”; and U.S. Pat. No. 4,328,908 patented May 11, 1982 to L. J. Temming and assigned to Staalkat B. V. on an “Apparatus For Denesting And Delivering The Bottom One Of A Stack Of Trays For Eggs”; and U.S. Pat. No. 4,355,731 patented Oct. 26, 1982 to J. C. Carroll et al and assigned to Phillips Petroleum Company on an “Egg Supporting Tray”; and U.S. Pat. No. 4,537,208 patented Aug. 27, 1985 to H. Y. Kuhl on a “Horizontal Flat Destacker”; and U.S. Pat. No. 4,650,390 patented Mar. 17, 1987 to T. Kay et al and assigned to Wand Tool Company, Inc. on “Stacker-Loader For Stacking Double Sided Printed Circuit Boards”; and U.S. Pat. No. 4,765,487 patented Aug. 23, 1988 to G. N. Bliss and assigned to Diamond Automations, Inc. on an “Automatic Article Stacking System”; and U.S. Pat. No. 4,787,799 patented Nov. 29, 1988 to K. Platteschorre on an “Egg Carton Stacking-Loading Device And Method”; and U.S. Pat. No. 4,844,188 patented Jul. 4, 1989 to V. Pirc et al and assigned to Pitney Bowes Inc. on an “Apparatus And Method Of Transporting Flats Across A Scale”; and U.S. Pat. No. 4,917,559 patented Apr. 17, 1990 to J. van der Schoot and assigned to Staalkat B. V. on a “Method And Apparatus Of Loading Or Unloading A Plurality Of Stacks Of Trays From A Container”; and U.S. Pat. No. 4,995,785 patented Feb. 26, 1991 to K. Platteschorre on an “Egg Carton Stacking-Loading Device And Method”; and U.S. Pat. No. 5,007,785 patented Apr. 16, 1991 to J. van der Schoot and assigned to Staalkat B. V. on a “Method And Apparatus For Unloading Stacks Of Trays”; and U.S. Pat. No. 5,104,115 patented Apr. 14, 1992 to M. Saito et al and assigned to Tokyo Electric Co., Ltd. on a “Stacker For Stacking And Issuing Sets Of Cards”; and U.S. Pat. No. 5,172,909 patented Dec. 22, 1992 to M. Ricciardi and assigned to Bell &amp; Howell Company on a “Secondary Pivotal Drive Stacker Roller Enabling Stacking of Small And Large Documents”; and U.S. Pat. No. 5,791,867 patented Aug. 11, 1998 to J. B. Kuhl on an “Apparatus For Automatically Unstacking Of Trays From A Vertically Extending Interlocking Stack Thereof”; and U.S. Pat. No. 5,807,065 patented Sep. 15, 1998 to J. B. Kuhl on an “Apparatus For Automatically Unstacking Horizontal Lid Members From A Vertically Extending Stack Thereof”; and U.S. Pat. No. 5,842,695 patented Dec. 1, 1998 to D. J. McVeigh and assigned to Xerox Corporation on a “Large Or Flimsy Sheets Stacking System For Disk Type Inverter-Stacker”; and U.S. Pat. No. 5,899,452 patented May 4, 1999 to M. Walsh and assigned to Coin Bill Validator, INc. on a “Stacker Mechanism For Stacking Bank Notes”; and U.S. Pat. No. 5,944,478 patented Aug. 31, 1999 to E. Colombo et al and assigned to Techint Compagnia Tecnica Internazionale S.p.A. on an “Automatic Stacker With Rotary Heads For Stacking, In An Ordered Manner In Alternate Upright And Inverted Layers, Metal Sections Originating From A Rolling Mill”; and U.S. Pat. No. 5,961,273 patented Oct. 5, 1999 to E. Coilombo et al and assigned to Techint compagnia Tecnica Internazionale S.p.A. on a “Stacker For The Stacking Of Metallic Section Bars In Alternating, Upright And Reverse Layers”; and U.S Pat. No. 6,241,458 patented Jun. 5, 2001 to E. H. Berndl and assigned to Skinetta Pac-Systeme Kiener GmbH &amp; Co. on a “Stacker For Grouping And Stacking Substantially Flat Articles”. 
     SUMMARY OF THE INVENTION 
     The present invention sets forth a uniquely defined apparatus for the purpose of placing horizontally oriented flats into vertically extending individual stacks thereof. Preferably the device includes a housing defining an inlet therein for receiving of these individual horizontally oriented stacks therethrough to facilitate positioning thereof into a vertically extending stack. The housing may preferably include an outlet for allowing exiting of the stack of flats after formed therefrom. 
     An inlet conveying device may also be included which is operative to transport the individual flats to the inlet of the housing for facilitating stacking therein. A stacking station is preferably defined within the housing which is adapted to receive flats from a position thereabove within the housing in registration therewith to facilitate vertical stacking of the horizontally oriented flats at this location. 
     An outlet conveying device is also included which extends into the stacking station within the housing through the outlet which is defined therein. This outlet conveyor will extend to the stacking station and will be operable to receive a stack of flats therefrom for exit conveying thereof through the outlet of the housing. The outlet conveyor extends below the stacking station preferably. Also preferably the stacking station is adapted to stack horizontally oriented stacks vertically directly upon the outlet conveyor in such a manner as to facilitate this exit conveying which takes place through the outlet defined in the housing. 
     An inlet delivery device is also included which is operative to urge movement of individual flats from the inlet conveyor into the housing. This inlet delivery enhancement device preferably includes a cylindrical roller brush positioned adjacent to the inlet conveyor which will contact flats being transported thereon to facilitate urging thereof for movement through the inlet into the housing. A roller drive may be operatively attached with respect to the cylindrical roller brush for driving rotatable movement thereof in order to facilitate movement of flats to move from a position on the inlet conveyor into the housing through the inlet. 
     An upper receiving station is defined within the housing adjacent to the inlet thereof and is operative to receive flats one at a time therewithin for orientation thereof above the stacking station and in vertical registration therewith. This upper receiving station preferably includes an upper retaining device selectively movable pivotally between an upper retaining position for holding of a flat within the upper receiving station and an upper releasing position for release of a single flat to allow downward movement thereof. 
     The upper retaining means preferably includes an upper rod pivotally mounted movably within the housing at a location laterally adjacent to a flat positioned within the upper retaining station. This upper rod will preferably include a first upper rod member mounted pivotally movable within the housing at a location laterally adjacent to a flat in the upper retaining position as well as a second upper rod member mounted pivotally movable within the housing at a position laterally adjacent to a flat positioned in the upper retaining station located at a position spatially distant from the position of the first upper rod member within the housing. 
     An upper arm mechanism is also included which is secured to the upper rod and is pivotally movable therewith between a flat retaining position extending below a flat for holding thereof in the upper receiving station means and a flat releasing position adjacent to a flat for allowing release of a flat downwardly therefrom. This upper arm mechanism preferably includes a first upper arm member secured to the first upper rod member and pivotally movable therewith between a flat retaining position extending below a flat for holding thereof in the upper receiving station and a flat releasing position adjacent a flat for allowing downward release therefrom. The upper arm mechanism further will preferably include a second upper arm member secured to the second upper rod and pivotally movable therewith between a flat retaining position extending below a flat for holding thereof in the upper receiving station and a flat releasing position adjacent a flat for allowing release thereof downwardly as necessary. 
     Furthermore the upper retaining mechanism can include a first upper control plate fixedly secured to the first upper rod member and pivotally movable therewith as well as a second upper control plate which is fixedly movable to the second upper rod member and pivotally movable therewith. An upper link may be included attached to the first upper control plate and the second upper control plate to be operative to cause simultaneous pivotal movement of these two parts together with respect to one another between the flat releasing position and the flat retaining position. This upper link is preferably movably attached to the first upper control plate and the second upper control plate to facilitate this coordinated movement thereof. Furthermore the upper link preferably is attached to the first upper control plate at a position above the first upper rod member and is attached to the second upper control plate at a position below the second upper rod member in order to facilitate coordinated pivotal movement of the first upper rod member and second upper rod member with respect to one another through the interconnection caused by the upper link means. 
     An intermediate accumulating station may be included located below the upper receiving station which is operative to receive individual flats moving downwardly from the upper retaining means of the upper receiving station for orientation thereof above the stacking station located therebelow and in vertical registration therewith. This intermediate accumulating station is preferably adapted to receive and retain a plurality of individual flats therewithin for simultaneous release together downwardly therefrom in order to facilitate stacking within the stacking station therebelow. The intermediate receiving station preferably includes an intermediate retaining device selectively movable pivotally between an intermediate retaining position for holding of at least one flat within the intermediate receiving station and an intermediate releasing position for release of at least one flat for allowing movement thereof downwardly to the stack station means located below. Preferably the number of flats retained prior to release within the intermediate station will be two or more. 
     The intermediate retaining mechanism includes an intermediate rod mounted pivotally movably within the housing at a location laterally adjacent to at least one flat positioned within the intermediate retaining means. The intermediate rod construction may include a first intermediate rod member being mounted pivotally movable within the housing at a location laterally adjacent to at least one flat positioned within the intermediate station. The intermediate rod mechanism may further include a second intermediate rod member mounted pivotally movable within the housing at a location laterally adjacent to a flat positioned within the intermediate retaining station at a position spatially distant from the first intermediate rod member with at least one flat positioned therebetween. The intermediate retaining device may further include an intermediate arm means secured to the intermediate rod mechanism and pivotally movable therewith between a flat retaining position extending below at least one flat for holding thereof in the intermediate receiving station means and a flat releasing position adjacent to at least one flat for allowing release thereof downwardly therefrom to the stacking station therebelow. The intermediate arm mechanism preferably includes a first intermediate arm member secured to the first intermediate rod member and pivotally movable therewith between a flat retaining position extending below at least one flat for holding thereof in the intermediate receiving station and a flat releasing position adjacent to at least one flat for allowing release thereof downwardly to the stacking station located therebelow. The intermediate arm mechanism may further include a second intermediate arm member secured to the second intermediate rod member and pivotally movable therewith between a flat retaining position extending below at least one flat for holding thereof in the intermediate receiving station and a flat releasing position adjacent at least one flat for allowing release thereof downwardly to the stack station therebelow. Further included can be a first intermediate control plate fixedly secured to the first intermediate rod member and pivotally movable therewith as well as a second intermediate control plate fixedly secured to the second intermediate rod member and pivotally movable therewith. Also preferably included is an intermediate link attached to the first intermediate control plate and a second intermediate control plate and operative to cause simultaneous pivotal movement of the first intermediate arm member and the second intermediate arm member between a flat releasing position and a flat retaining position thereof. The intermediate link is preferably movably attached to the first intermediate control plate and the second intermediate control plate to facilitate this coordinated movement therebetween. Furthermore the intermediate link preferably is attached to the first intermediate control plate above the location of the first intermediate rod member and is also attached to the second intermediate control plate below the second intermediate rod member in order to facilitate this coordinated pivotal movement of the first intermediate rod member and the second intermediate rod member simultaneously together in the opposite pivotal direction. The intermediate retaining device is preferably operative in the steady state position to be located in the retaining position and is operative to move to the releasing position only responsive to a plurality such as four flats being located within the intermediate accumulating station for allowing release therebelow. It is operative to return to the retaining position subsequent to release of all the flats within the station. Also included in the apparatus of the present invention may be an intermediate sensing device which monitors the presence of flats retained within the intermediate accumulating station and is operative to urge the movement of the intermediate retaining means to the releasing position only in the situation where a plurality of individual flats have been accumulated therein and more preferably only after at least four or more such flats are accumulated therewithin. 
     Also the apparatus of the present invention may include a stack sensing device which is operative to monitor the exiting of movement of a stack from the stack receiving station through the outlet and is operative to prevent the release of flats downwardly from the intermediate accumulating station toward the stacking station during exiting movement of a stack of flats from the stacking station moving outwardly toward and through the outlet of the housing. 
     In operation the apparatus of the present invention initially conveys horizontally oriented flats or trays one at a time into an upper receiving station of a stacker housing. This stack now within the upper receiving station will be registered vertically such that it is positioned directly above an intermediate accumulating station therebelow as well as directly above a stack station further therebelow but also located within the stacker housing. The stacks are released one at a time from the upper receiving station such that they move downwardly to be held within the intermediate accumulating station by an intermediate retaining means. Flats are then accumulated in an intermediate stack within the intermediate accumulating station until a plurality of individual flats are stacked therewithin. This intermediate stack is then released by movement of the intermediate retaining apparatus to the release position in order to allow movement of this intermediate stack downwardly simultaneously together to the stacking station therebelow. In the stacking station a completed stack of flats will be formed by repeated releases of intermediate stacks from thereabove until the number of flats stacked within the stacking station is to the desired level. At that time the stack of flats located in the stacking station will be exit conveyed outwardly through the outlet defined in the stacker housing for further processing such as movement to a spin dryer or other similar apparatus. 
     It is an object of the present invention to provide an apparatus and method for placing horizontally oriented flats into a vertically extending stack thereof to facilitate further processing such as drying or transporting or storage thereof. 
     It is an object of the present invention to provide an apparatus and method for placing horizontally oriented flats into a vertically extending stack thereof which occupies a minimum footprint of floor space. 
     It is an object of the present invention to provide an apparatus and method for placing horizontally oriented flats into a vertically extending stack thereof which is easily maintained. 
     It is an object of the present invention to provide an apparatus and method for placing horizontally oriented flats into a vertically extending stack thereof which includes a minimum number of moving parts. 
     It is an object of the present invention to provide an apparatus and method for placing horizontally oriented flats into a vertically extending stack thereof which can be utilized in multiple laterally positioned configurations of as many as four or more individual rows. 
     It is an object of the present invention to provide an apparatus and method for placing horizontally oriented flats into a vertically extending stack thereof which allows stacking to continue at the intermediate station even during exit conveying of a completed stack from the stacker station and in this manner greatly increase the operating speed and efficiency of the flat stacking operation. 
     It is an object of the present invention to provide an apparatus and method for placing horizontally oriented flats into a vertically extending stack thereof which can be used with flats made of various configurations. 
     It is an object of the present invention to provide an apparatus and method for placing horizontally oriented flats into a vertically extending stack thereof which can be used with flats made of various different materials such as plastic, fibrous materials or any other material. 
     It is an object of the present invention to provide an apparatus and method for placing horizontally oriented flats into a vertically extending stack thereof which can be used with flats which nest as well as used with flats which do not nest with respect to one another. 
     It is an object of the present invention to provide an apparatus and method for placing horizontally oriented flats into a vertically extending stack thereof which includes an enhanced infeed system such as a circular roller or brush for urging individual flats to the initial receiving station positioned directly vertically above the final stacking position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     While the invention is particularly pointed out and distinctly claimed in the concluding portions herein, a preferred embodiment is set forth in the following detailed description which may be best understood when read in connection with the accompanying drawings, in which: 
     FIG. 1 is a side perspective view of an embodiment of the apparatus of the present invention for placing horizontally oriented flats into a vertically extending stack thereof and method of use; 
     FIG. 2 is an end plan view of the embodiment shown in FIG. 1; 
     FIG. 3 is a top cross-sectional view of FIG. 2 taken along lines  3 — 3 ; and 
     FIG. 4 is a top cross-sectional view of FIG. 2 taken along lines  4 — 4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention provides a unique high speed configuration for efficiently forming stacks  12  of flats  10 . Such flats are normally horizontally oriented members which include a shape or configuration designed defined therein to hold a plurality of individual discrete members. One common use of such flats is for holding an array of individual items such as eggs or fruits or other similar material therewithin. The present invention is particularly usable for handling flats configured for holding eggs. It is very important to appreciate that such flats need to be washed and dried after each use for sanitary purposes. Washing needs to occur in a very thorough manner due to the substantial sterilization and other contaminant problems associated with flats  10  which can have organic contaminants extending thereover. 
     As such, during washing the stacks need to be individually separated from one another. However for handling and sometimes for drying the flats  10  need to be stacked. These stacks preferably include preferably fifteen to twenty individual flats but can be stacked as high as forty or more such flats. The present apparatus provides a unique configuration for receiving on the infeed horizontally oriented stacks such as immediately after washing and for stacking of these flats  10  into vertically extending stacks  12  within a stacker housing  14  for outfeeding therefrom. This apparatus can be operated in one individual line or can have as many as four or more separate and independent operating lines arranged adjacent to one another each receiving horizontally oriented flats one at a time for stacking thereof. Once these stacks of flats are formed they can be handled or processed much more easily such as for drying, shipment or positioning for reuse. 
     The stacker housing  14  preferably includes an inlet  16  at the upper end and an outlet  18  near the lower end thereof. The inlet  16  is designed to receive individual flats  10  moving therethrough and the outlet  18  is designed to allow stacks of flats  12  to be exit conveyed therethrough. 
     An inlet conveyor  20  is preferably positioned adjacent to the inlet  16  of housing  14  to move individual flats  10  thereadjacent. The housing defines an upper receiving station  32  immediately adjacent to the inlet  16  for receiving of the flats  10  one at a time. An inlet delivery means  26  may be positioned adjacent to the inlet conveyor  20  and the upper receiving station  32  to facilitate movement of flats  10  individually into the upper receiving station  32 . The design of this inlet delivery means  26  may include a cylindrical roller  28  which can be driven by a roller drive means  30 . The rotation of the cylindrical roller will cause the outer periphery of the cylindrical roller or cylindrical brush  28  to contact the upper surface of the flat  10  to facilitate and urge movement thereof through the inlet  16  to be fully placed within the upper receiving station  32 . 
     This full placement of the flat  10  into the receiving station  32  is very important because the upper receiving station  32  is oriented in vertical registration immediately above an intermediate accumulating station  62  therebelow and a stacking station  22  further therebelow. The stacking station  22  is positioned adjacent to the outlet conveyor  24  for the purpose of providing stacks of flats  12  thereto for exit conveying thereon through the outlet  18 . This vertical registration of the upper receiving station  32  and the intermediate accumulating station  62  therebelow and the stacking station  22  further therebelow is an important aspect of the present invention since it allows direct downward movement of the flats and stacks of flats and greatly facilitates the formation of the final stack of flats  12  within the stacking station  22  which is the ultimate goal of the apparatus of the present invention. 
     The upper receiving station  32  includes an upper retaining means  34 . This upper retaining means preferably is moved between an upper retaining position  36  for holding of a flat  10  in the upper receiving station  32 . Upper retaining device  34  is movable selectively to an upper releasing position  38  to allow release of a flat  10  for movement downwardly therefrom toward the intermediate accumulating station  62  located therebelow. 
     This upper retaining device  34  is accurately controlled for movement between the upper retaining position  36  and the upper releasing position  38  in order to release the flats  10  one at a time for movement downwardly to the intermediate accumulating station  62 . 
     The upper retaining means  34  preferably includes an upper rod mechanism  40  which can include a first upper rod member  42  and a second upper rod member  44 . Preferably the first upper rod member  42  is positioned adjacent to one side of a flat  10  when located within the upper receiving station  32  and the second upper rod member  44  is positioned adjacent the opposite end thereof. An upper arm mechanism is secured with respect to the upper rod and is movable along therewith to facilitate movement of the upper arms between a flat retaining position  48  and a flat releasing position  50 . The flat retaining position  48  of the upper arm  46  corresponds to the upper retaining position  36  of the upper retaining means  34 . In a similar manner the flat releasing position  50  of the upper arm  46  corresponds to the upper releasing position  38  of the upper retaining means  34 . Preferably the upper arm includes a first upper arm member  52  which is mounted in the first upper rod member  42  and a second upper arm member  54  which is mounted in the second upper rod member  44 . Pivotal movement of the first upper arm member  52  and second upper arm member  54  is achieved by rotational movement of the first upper rod member  42  and the second upper rod member  44  for pivotal movement thereof relative to the housing  14  in which they are mounted. This movement is controlled by a first upper control plate  56  attached to the first upper rod member  42 . In a similar manner, a second upper control plate  58  is attached to the second upper rod member  44 . As such, rotation of the respective control plates  56  and  58  will cause pivotal movement of the first and second rod members  42  and  44 , respectively and simultaneous movement of the first upper arm member  52  and the second upper arm member  54  respectively between the releasing position and the retaining position allowing release of individual flats from the upper receiving station  32  one at a time as accurately controlled. This coordinated movement of the first upper control plate  56  and the second upper control plate  58  is achieved through an upper link  60  which is preferably movably secured to each of these members and extends therebetween. Powering of movement of the upper link  60  and the first and second upper control plates  56  and  58  is preferably achieved by an upper extensible piston means  96  shown best in FIG. 2 for urging movement of the entire upper retaining means  34  between the upper retaining position  36  and the upper releasing position  38 . Upon viewing the figures of the present invention, it is clearly apparent that the first and second upper arm members  52  and  54  are movable to a position beneath the flat  10  located in the upper receiving station  32  when retaining the flat in place and to a position outwardly laterally such as to allow the flat  10  to move downwardly toward the intermediate accumulating station therebelow. It is important to understand that the upper receiving station  32  is adapted to handle flats  10  one at a time and will not receive an additional flat until the flat which is located therein is already released for movement toward the intermediate accumulating station  62  therebelow. 
     The intermediate accumulating station  62  preferably includes an intermediate retaining means  64  which is movable between an intermediate retaining position  66  and an intermediate releasing position  68 . When in the intermediate retaining position  66 , the intermediate retaining means  64  will hold one or more flats  10  in position in the intermediate accumulating station  62 . When the intermediate retaining means  64  is moved to the intermediate releasing position  68 , one or more flats  10  retained within the intermediate accumulating station  62  will be released to allow downward movement thereof toward the stacking station  22  therebelow. 
     Intermediate retaining means  64  will preferably include an intermediate rod mechanism  70 . This rod mechanism  70  can preferably include a first intermediate rod member  72  and a second intermediate rod member  74 . It should be appreciated that the basic construction of the intermediate retaining means  64  is similar to the basic construction of the upper retaining means  34  except that the intermediate retaining means  64  is designed to remain in the retaining position until a plurality of flats  10  are accumulated therein for release therebelow. On the other hand the upper retaining means  34  is designed to move to the upper releasing position  38  whenever at least one flat  10  is positioned within the upper receiving station  32 . 
     An intermediate arm mechanism  76  is preferably attached with respect to the intermediate rod  70  to be movable therewith. This intermediate arm is movable between a flat retaining position  78  and a flat releasing position  80 . In position  80 , it will be operable to release a plurality of flats  10  for downward movement thereof toward the stacker station  22  located therebelow. Preferably the intermediate arm mechanism  76  will include a first intermediate arm member  82  and a second intermediate arm member  84 . These arm member  82  and  84  will preferably be positionable on opposite sides of the plurality of flats  10  being accumulated within the intermediate accumulating station  62  to facilitate retaining thereof. A first intermediate control plate  86  will be preferably fixedly secured to the first intermediate rod member  72  and the second intermediate control plate  88  will preferably be fixedly secured with respect to the second intermediate rod member  74 . In this manner an intermediate link  90  can be movably secured to the first intermediate control plate  86  and the second intermediate control plate  88  to maintain coordinated movement therebetween. This will achieve coordinated movement of the first intermediate arm member  82  and the second intermediate arm member  84  between the flat retaining position within the intermediate accumulating station  62  extending below flats  10  therein and the flat releasing position  80  therewithin. 
     The intermediate accumulating station  62  will, in this manner, be capable of accumulating a plurality of stacked flats therein for release simultaneously in groups of two or more and preferably four or more downwardly for movement to the stacking station  22 . One of the important advantages of the apparatus of the present invention is that the intermediate accumulating station  62  can continue to operate even after it releases the final intermediate stack for movement downwardly to the stacking station  22  after which the stacking station will initiate exit conveying. That is, once the intermediate accumulating station  62  releases the final intermediate stack of flats downwardly such that exit conveying can be initiated, the intermediate stacking operation will continue to build an intermediate stack  100  within the intermediate accumulating station  62 . In most prior art configurations the stacking would cease during the time of exiting by the accumulated stack. That is, once the completed final stack initiates exit from the final stacking location  22 , there would be a hesitation in operation of the mechanism because no further flats can be allowed to be moved downwardly into the stacking station  22  until it is completely empty and the entire completed stack has exited therefrom. However, with the present apparatus, intermediate stacking within the intermediate stacking station  22  can be allowed to continue since no stacking will actually occur in the stacking station  22  but will occur in the intermediate accumulating station  62  only. Thus, no interference will occur between the exiting completed stack and the intermediate stack  100  being formed in the intermediate accumulating station. As the stacking station  22 , initiates exit movement of a completed stack, further flats will be stacked continuously and without interruption within the intermediate accumulating station  62 . Normally this intermediate accumulating station  62  is designed to accumulate as many as four such flats. By the time four flats are accumulated within the intermediate accumulating station  62 , the completed stack  12  of flats  10  will surely have finally exited and the stacking station  22  will be again available to receive more flats  10  for stacking when the intermediate accumulating station  22  again is ready to move to the releasing position  68  for downward movement. Thus the dead time which normally occurs during exit conveying of a completed stack will be avoided due to the intermediate stacking that occurs within the intermediate accumulating station in the apparatus or method of the present invention. 
     The present invention will further preferably include an intermediate sensing means  92  positioned adjacent to the intermediate accumulating station  62  for the purpose of determining when a sufficient number of flats  10  have been accumulated within the intermediate stack  100  thereof for release thereof downwardly. When this height is reached the stack is ready to be conveyed outwardly therefrom. The intermediate sensing means  92  will then generate a signal to initiate movement of the intermediate retaining means  64  to the intermediate releasing position  68  to allow release of the accumulated intermediate stack  100  of flats  10  for movement thereof downwardly toward the stacking station  22 . The intermediate arms are timed to open after the upper arms have opened a predetermined number of times, which is usually chosen to be four times for accumulating four flats at a time but the number could be any predetermined value. 
     Preferably the present invention will also include a stack sensing means  94  which will sense whenever exit conveying occurs and will transmit this signal to the intermediate accumulating station  62  to prevent movement thereof to the intermediate releasing position  68  to prevent the release of flats  10  downwardly until the stack of flats  12  has completely exited the stacking station  22 . This stack sensing means  94  is a backup sensing means to assure smooth operation. In normal operation the stack sensing means  94  will not be needed since the exit conveying will be initiated whenever an intermediate stack  100  moves downwardly such that a completed stack is formed. Thus immediate exit conveying will occur and the intermediate accumulating station  62  will need some additional time to accumulate sufficient individual stacks  10  therein such that it is ready for movement to the intermediate releasing position  68 . Thus the stack sensing means  94  is a backup system to be sure that intermediate stack  100  of flats  10  are not released for downward movement from the intermediate accumulating station  62  during exit conveying of the completed stack by the stacking station  22 . 
     Movement of the intermediate arm mechanism  76  between the flat retaining position  78  and the flat releasing position  80  is controlled by an intermediate extensible piston means  98 . This piston is connected with respect to the mechanism of the first intermediate control plate  86 , second intermediate control plate  88  and intermediate link  90  in such a manner as to control movement thereof between the flat releasing position and the flat retaining position and vice versa. 
     While particular embodiments of this invention have been shown in the drawings and described above, it will be apparent, that many changes may be made in the form, arrangement and positioning of the various elements of the combination. In consideration thereof it should be understood that preferred embodiments of this invention disclosed herein are intended to be illustrative only and not intended to limit the scope of the invention.