Abstract:
Some manufacturing processes include forming stacks of manufactured objects for handling and/or processing. While some such manufactured objects are consistent in thickness, other are more irregular. Some manufactured objects are generally flat, but are also generally thicker along one edge. When objects having these characteristics are stacked, the cumulative effect of such inconsistent thickness results in an unbalanced stack. The disclosed apparatus and method utilize a novel rotating stacker that rotates the stack of manufactured objects as each new object is added to the stack, thereby distributing the thickness inconsistency of individual objects throughout the stack, producing a more uniform stack without manual intervention.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0001]    The invention is directed to an apparatus and method for creating a stack of manufactured objects, particularly flatbreads. 
       Description of the Related Art 
       [0002]    Methods and apparatuses for creating and managing stacks of manufactured products are well known. One such manufactured product is flatbread. ‘Flatbread’ is considered to encompass: thick and thin tortillas, made either of corn, wheat, or any other type of flour; piadinas; naan; paratha; roti; chapatti; lavash; focaccia; wraps; pita; and pizza crust. 
         [0003]    Flatbread is generally a baked dough product. Even if dough begins as perfectly disc-shaped prior to baking, the inherent heterogeneous nature of dough results in inconsistencies in perimeter and thickness of the final product. Moreover, it has been discovered by the present inventors that a common method for flatbread production leads to an inherent inconsistency in the final product. When produced on an industrial scale, it is common to use a die-cut process to form the dough discs that are baked into flatbreads. Dough is passed through a matched set of rollers or a roller and a platen that produce an extrusion of dough. Dies in the roller cut discs from the dough extrusion. The discs are baked into flatbread, while the remainder is discarded or passed back into the process for re-extrusion. 
         [0004]    The present inventors have discovered that as the dough extrusion passes through the dies, the dough is pressed against a forward edge of each die. As a consequence, while the final flatbread product has irregularities due the baking process, a forward edge of each flatbread product is, on average, thicker than a remaining portion. As a consequence, when a stack of flatbreads is created without any change in the orientation of the flatbreads, the slightly thicker portions of the flatbreads are generally aligned within the stack. This has a cumulative effect in the stack, leading to a stack that is curved instead of being vertical. If this curve is not corrected prior to packaging in a bag, the packaged stack will also be curved. This causes problems as bags of stacked flatbreads are themselves stacked, leading to difficulties in transportation and display for sale. Such curved stacks are also considered less appealing to consumers, who desire consistency in many manufactured food products. 
         [0005]    In the absence of a rotating stacker as disclosed, it has been necessary to have personnel manually ‘shuffle’ each stack of flatbreads to produce a stack that is generally straight prior to packaging. This increases cost, relies on the attention to detail of personnel, and increases human contact with the flatbread. These are all disadvantages that can be remedied by the present rotating stacker. 
         [0006]    In addition to flatbread products that are known to produce a thicker forward edge, it has been discovered that even in connection with flatbread products that do not generally have a thicker forward edge due to the manufacturing process, the stack of products can be improved by rotating the stack during stack formation. One reason is the fact that certain manufactured products do not fall cleanly onto a stack support as they are transferred thereto. Rotating the stack during stack formation helps some such products settle into place, forming a more uniform stack. Even if the rotation does not cause the product to fully settle into position, it is possible that the manufactured products end up with a foremost edge of the product leaning against the machinery that helps form the stack. As the stack is rotated during stack formation, these edges will be evenly distributed around the circumference of the stack, thereby avoiding the cumulative effect of keeping these edges aligned. 
       SUMMARY OF THE INVENTION 
       [0007]    To address the problems inherent in creating stacks of manufactured products, in particular flatbreads, a method and apparatus that utilizes a rotating stacker is provided. In such method and apparatus, manufactured objects are conveyed to a stack support to create a stack of such objects. As each successive object is added to the stack, the stack support rotates. In this way, the rotational orientation of the various objects in the stack is distributed throughout a range, thereby avoiding a cumulative effect of inconsistencies in the thickness of the objects as the stack is created. 
         [0008]    In a first embodiment, a rotating stacker includes: a stack support; an input conveyor arranged so that objects transported by the input conveyor can be moved toward and be supported by the stack support, thereby forming an object stack; an output conveyor arranged so that the object stack can be moved off of the stack support. The stack support is constructed and arranged to assume a plurality of different rotational positions with respect to the input conveyor as the input conveyor transports the objects to the stack support while a single object stack is formed. 
         [0009]    In various other embodiments, the stack support is constructed and arranged so as not to rotate while each object is being added to the object stack. The stack support can be made to rotate through a fixed predetermined rotation angle during a time between successive objects being added to the object stack. The stacker can be made to be adjustable by a user to set the rotation angle to a desired value. 
         [0010]    Alternatively, the rotating stacker of claim can be made to rotate continuously while the object stack is being formed, and can be adjustable by a user to set a rate at which the stack support continuously rotates while the object stack is being formed. 
         [0011]    In other embodiments, the stack support moves vertically with respect to the input conveyor as the object stack is formed, and such vertical movement can be downward. In one variation, the stack support moves downward with respect to the input conveyor as the object stack is formed so as to maintain a generally consistent position of a top of the object stack with respect to the input conveyor. 
         [0012]    In a method for creating a stack of object, steps can include: a) moving the objects toward a stack support so that each of the objects comes to rest on the stacker or another object supported by the stacker; b) repeating step a) until a full stack of the objects on the stack support is formed; and c) moving the full stack off of the stack support; wherein the stack support is rotated as the step a) is repeated so that at least one of the objects is effectively rotated with respect to another of the objects on the stack. 
         [0013]    In one variation of such method, step a) is performed so that the stack support does not rotate while each object is being added to the object stack. The stack support can be made to rotate through a fixed predetermined rotation angle during a time between successive objects being added to the object stack. The stack support can rotate continuously while the object stack is being formed. 
         [0014]    In another variation, step a) is performed so that the stack support moves vertically with respect to the input conveyor as the object stack is formed, and such vertical movement can be downward. More specifically, step a) can be performed so that the stack support moves downward with respect to the input conveyor as the object stack is formed so as to maintain a generally consistent position of a top of the object stack with respect to the input conveyor. 
         [0015]    In embodiments directed specifically to a rotating stacker for flatbread, the device can include: a stack support; an input conveyor arranged so that flatbreads transported by the input conveyor can be moved toward and be supported by the stack support, thereby forming a flatbread stack; and an output conveyor arranged lower than the input conveyor so that the flatbread stack can be moved off of the stack support. The stack support can include a platform on a top end of a rod, the rod being controlled to perform vertical motion between upper and lower positions, the upper position placing the stack support relatively nearer the input conveyor, the lower position placing the stack support relatively nearer the output conveyor. 
         [0016]    The rod can also be controlled to perform rotational motion so as to rotate the stack support and any of the flatbreads in the flatbread stack resting on the stack support. The rotating flatbread stacker can repeatedly raise the rod to the upper position to create a new flatbread stack, and for each flatbread that is added to the stack by the input conveyor, perform the vertical motion to lower the stack so as to keep a top of the flatbread stack in generally a constant position with respect to the input conveyor, and perform the rotational motion, until the flatbread stack is complete. At that point, the rod can be moved to the lower position so the output conveyor can move the flatbread stack away from the stack support. 
         [0017]    ‘Flatbread’ is considered to include, but not necessarily be limited to: thick and thin tortillas, made either of corn, wheat, or any other type of flour; piadinas; naan; paratha; roti; chapatti; lavash; focaccia; wraps; pita; and pizza crust. 
         [0018]    In one embodiment of the flatbread stacker, the stack support does not rotate while each flatbread is being added to the flatbread stack. The stack support can be made to rotate through a fixed predetermined rotation angle during a time between successive flatbreads being added to the flatbread stack, and can be adjustable by a user to set the rotation angle to a desired value. 
         [0019]    Alternatively, the stack support can rotate continuously while the flatbread stack is being formed, and can be adjustable by a user to set a rate at which the stack support continuously rotates while the object stack is being formed. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0020]    The apparatus and method will be described in connection with the attached drawings in which 
           [0021]      FIG. 1  is a generalized block diagram of the apparatus; 
           [0022]      FIG. 2  illustrates an exemplary input conveyor; 
           [0023]      FIGS. 3A and 3B  illustrate two examples of an input conveyor; 
           [0024]      FIGS. 4A-4D  illustrate various positions of a support plate; 
           [0025]      FIG. 5  illustrates details of an input conveyor; 
           [0026]      FIG. 6  illustrates a support plate recessed into an output conveyor; 
           [0027]      FIG. 7  illustrates a support plate in an upper position; 
           [0028]      FIG. 8  illustrates a support plate in a lower position; 
           [0029]      FIGS. 9A-9F  illustrate formation of a stack of objects; 
           [0030]      FIGS. 10A-H  illustrate various positions of a support plate in use; and 
           [0031]      FIG. 11  is a flowchart describing operation of the apparatus. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0032]    As generically illustrated in  FIG. 1 , a representative embodiment of a rotating stacker includes three elements: an input conveyor  100 , a stack support  200 , and an output conveyor  300 . The three elements can be configured to transport objects via the input conveyor  100  to the stack support  200 . The objects are then formed into a stack on the stack support  200  in such a way that the stack support  200  rotates during formation of the stack. When a full stack of the objects has been created on the stack support  200 , the full stack is transported away from the stack support  200  via the output conveyor  300  for further handling. 
         [0033]    The input conveyor can take any of a number of forms known in the field of material handling and transport. These can include, but are not limited to, slip-torque conveyors, belt conveyors, gravity rollers, powered rollers, circular conveyors, spiral chutes, air cushion, or any other conveyance mechanism appropriate for the object being stacked. For purposes of illustration,  FIG. 2  illustrates a set of rollers  101 , each held rotatably in place by roller supports  102 . Rollers  101  can be free to rotate, thereby allowing objects being conveyed by such rollers to move by force of gravity, or the rollers can be driver by a motor  103 , as shown schematically in  FIG. 2 . 
         [0034]      FIG. 3A  illustrates the input conveyor of  FIG. 2 , in addition to an object  401  being transported thereby. Object  401  rests on rollers  101 . Object  401  moves in the direction of the arrow in conjunction with rotation of rollers  101 . 
         [0035]    An alternative to the device of  FIG. 2  and  FIG. 3A  is the roller arrangement of  FIG. 3B . In this embodiment, each of the rollers  101  is replace by multiple partial rollers  111 . A set of partial rollers  111  share a shaft  114 . Each set of partial rollers  111  may be fixed to its respective shaft  114 , freely rotatable independently about its respective shaft  114 , or connected by a slip-torque arrangement to its respective shaft  114 . In a slip-torque arrangement, each shaft  114  is driven by a motor  103 , illustrated schematically. Each shaft  114  imparts such rotational motion to the partial rollers  111  attached to such shaft  114 . The interconnection between each partial roller  111  and its shaft  114  is such that in the event of a given amount of resistance to such rotational motion experienced by a given partial roller  111 , the partial roller  111  will rotate at a lower rate than its shaft  114 , or will not rotate at all. 
         [0036]    This may be useful in the connection with one or both of the input conveyor  100  and the output conveyor  300 , in installations in which the objects being conveyed and stacked may be stopped at various points while being transported by the input or output conveyors  100  or  300 . A slip-torque roller arrangement allows the continuous driving of the roller system without producing abrasion of the objects being transported while they are held in place. 
         [0037]    From the perspective of workflow and object travel, stack support  200  is between input and output conveyors  100  and  300 . Stack support  200  provides the mechanism to allow formation of a stack of objects delivered by input conveyor  100 . Such mechanism can include adjustment of a height of stack support  200 , which in turns adjusts the height of the stack of objects being formed on stack support  200 . Such mechanism can also include rotation of the stack during stack formation. 
         [0038]      FIG. 4A  through  FIG. 4D  illustrate stack support  200 , including base  201  onto which is mounted platform  202 . Platform  202  can move linearly along a face of base  201 .  FIG. 4A  and  FIG. 4B  illustrate stack support  200  with platform  202  in lower and upper positions. Such motion is provided through platform motor  203 . 
         [0039]    Support shaft  204  is rotationally mounted at a first end to platform  202 . Support shaft motor  205  provides the rotation of support shaft  204  with respect to platform  202 . Support plate  206  is fixed to a second end of support shaft  204 .  FIG. 4C  and  FIG. 4D  illustrate support shaft  204  and support plate  206  rotated into two different positions. 
         [0040]    Input conveyor  100  can further include slide plate  104  and backstop  105 , as illustrated in  FIG. 5 . As objects being stacked transition from input conveyor  100  to stack support  200 , momentum of the objects moving across partial rollers  111  carries the objects across slide plate  104 . Further movement of the objects is stopped by backstop  105 . Once each object makes contact with backstop  105 , it drops onto stack support  200 . 
         [0041]    Support plate  206  can be shaped in such a way as to allow a transfer of one or more objects supported by support plate  206  to output conveyor  300 . As illustrated in  FIG. 6 , support plate  206  can be shaped so that it provides the necessary support for the objects being stacked, while also being able to recess into output conveyor  300 . In an arrangement using partial rollers  111 , support plate  206  can be shaped so that its upper surface drops below a highest point of each partial roller  111 . As support plate  206  descends into this position, any object or stack of objects supported thereby will transition to support by the partial rollers  111 . This allows the object or stack of objects to be transported off by the output conveyor  300 . 
         [0042]    Alternative shapes for support plate  206  can be readily produced to accommodate various configurations of output conveyor  300 . 
         [0043]      FIG. 7  and  FIG. 8  illustrate an arrangement of input conveyor  100 , stack support  200 , and output conveyor  300  in two different positions.  FIG. 7  illustrates the components in position ready to create a new stack.  FIG. 8  illustrates the components as they may appear when a complete stack has been created, and the stack is ready to be transported away by output conveyor  300 . In  FIG. 7 , platform  202 , support shaft  204 , and support plate  206  are in their upper positions, and support plate  206  is positioned near a level of the partial rollers  111  of input conveyor  100  and slide plate  104 . In  FIG. 8 , these components are in their lower positions, and support plate  206  is recessed into partial rollers  111  of output conveyor  300 . With an upper face of support plate  206  below the upper points of partial rollers  111 , and object or stack of objects would be supported by partial rollers  111 . Lowering of support plate  206  to this position thereby effects a transfer of an object or stack of objects from support plate  206  to partial rollers  111  of output conveyor  300 . 
         [0044]      FIG. 9A  through  FIG. 9F  illustrate the stacker as described thus far. In  FIG. 9A , the apparatus is in position to create a new stack of objects  401 . Two objects  401  are being transported by input conveyor  100  as they travel across partial rollers  111 . The first of the two objects  401  has transitioned from partial rollers  111  to slide plate  104 . Its momentum from being carried along by partial rollers  111  causes object  401  to slide across slide plate  104 . 
         [0045]    In  FIG. 9B , the first of the two objects  401  has moved across slide plate  104  and continued onto support plate  206 . The forward movement of object  401  was stopped by its contact with backstop  105 , causing object  401  to come to rest on support plate  206 . The second object  401  continues to travel along partial rollers  111  of input conveyor  100 . In conjunction with the object  401  coming to rest on support plate  206 , the linearly movable portion of stack support  200  moves downward. This downward movement is on the order of the thickness of a single object  401 . In this way, as a stack of objects  401  is formed the top of such stack is approximately at the height of an upper surface of support plate  206  when the first object  401  is dropped onto the support plate  206  at the beginning of the formation of a stack. 
         [0046]    In  FIG. 9C , the first two objects  401  have been transferred onto support plate  206 , starting a stack of objects  401 . The linearly movable portion of stack support  200  has descended to maintain a top of the stack of objects  401  at a generally constant height relative to input conveyor  100 . 
         [0047]    In  FIG. 9D , a full stack of objects  401  has been formed. Through an appropriate control mechanism, any further objects  401  are halted from proceeding along input conveyor  100 . The linearly movable portion of stack support  200  then lowers to the position first illustrated in  FIG. 8 .  FIG. 9E  shows the apparatus and stack in this position. With support plate  206  in its lowest position, recessed into partial rollers  111  of output conveyor  300 , objects  401  are now supported by partial rollers  111 , and are no longer resting on support plate  206 . This allows the stack of objects  401  to be transported by output conveyor  300  for further processing.  FIG. 9F  illustrates the stack of objects  401  being transported by output conveyor  300  away from support plate  206 . 
         [0048]    Objects  401  illustrated herein are shown to have planar faces and without inconsistency. For objects formed this precisely, there may be no requirement to rotate support plate  206  during formation of the stack of objects  401 . However, there are other objects of manufacture that, while generally flat, are slightly irregular in shape. One such manufactured object is the food item called flatbread. For present purposes, the term ‘flatbread’ is considered to encompass: thick and thin tortillas, made either of corn, wheat, or any other type of flour; piadinas; naan; paratha; roti; chapatti; lavash; focaccia; wraps; pita; and pizza crust. The remaining description addresses a stacking method and apparatus that are particularly well suited to forming stacks of objects that have such inconsistency. 
         [0049]      FIG. 10A  through  FIG. 10G  illustrate a representative sequence of movements of stack support  200  during a stacking operation. For clarity of illustration, the pertinent portions of stack support  200  are shown in isolation, and without any of the objects being stacked.  FIG. 10A  shows support plate  206  in its initial, highest position, corresponding to that of  FIG. 7 . This shows the position of stack support  206  as it is ready to accept a first of the objects to be stacked. 
         [0050]      FIG. 10B  through  FIG. 10G  illustrate the incremental position of support plate  206  after an additional object is added to the stack of objects. In each sequential position, support plate  206  is lower, and its rotational orientation has been adjusted. This sequence can continue until a stack of the desired size is obtained. Once the desired stack has been created, stack support  200  moves to the position illustrated in  FIG. 10H . In this position, the rotational orientation of support plate  206  is set so that it is properly aligned with partial rollers  111 , and the height of support plate  206  relative to partial rollers  111  of output conveyor  300  is such that an upper surface of support plate  206  is lower than a top of each of partial rollers  111  in output conveyor  300 , to effect a transfer of the stack of objects from support plate  206  to partial rollers  111  of output conveyor  300 . This corresponds to the position illustrated in  FIG. 8 . 
         [0051]    Operation of the apparatus will be described in connection with the flowchart of  FIG. 11 . At the beginning of operation, in step S 501 , support plate  206  is moved to its start position. This corresponds to the position illustrated in  FIG. 7 . In step S 502 , a first of the objects to be stacked is moved by input conveyor  100  so that the object comes to rest on support plate  206 . This is in process in  FIG. 9A . In step S 503 , support plate  206  is rotated via support shaft motor  205  and lowered via platform motor  203 . This rotation and lowering is illustrated in the sequence illustrated in  FIGS. 10A-B . 
         [0052]    In step S 504 , the next object is transferred via input conveyor  100  to be supported by support plate  206 . As this is not the first object on the stack, instead of coming to rest directly upon support plate  206 , it instead is in contact with the most recent object added to the stack. This corresponds to  FIG. 9C . 
         [0053]    The apparatus that determines whether the stack is complete. This determination can be made by any of a number of known methods, using known sensors. This can include one or more devices to detect the number of objects in the stack, the height of the stack, or the weight of the stack. If the stack is not complete, steps S 503  and S 504  are repeated. 
         [0054]    If it is determined that the stack is complete, no further objects are added to the stack. In step S 506 , support plate  206  is rotated via support shaft motor  205  so that support plate  206  is rotationally aligned with output conveyor  300 . When properly aligned, support plate  206  is lowered via platform motor  203  to its bottom position is step S 507 . This condition of the apparatus is illustrated in  FIG. 8 , although without the object stack. In such position, an upper surface of support plate  206  is below a highest point of a conveying surface of output conveyor  300 , in this case partial rollers  111 . In this position, the object stack is no longer supported by support plate  206 , but is instead supported by output conveyor  300 . In step S 508 , the object stack, now supported by output conveyor  300 , is transported away from support plate  206  for further processing. 
         [0055]    In step S 509 , the determination is made whether to create another stack of objects. If so, the entire process is repeated. 
         [0056]    A great number of variations and options are available to adapt the disclosed method and apparatus to different conditions. The nature of the rotation can be modified to best suit the characteristics of the objects being stacked and manufacturing priorities. 
         [0057]    In some embodiments, the rotation is incremental. The rotation occurs in a series of discrete steps during each stack formation. The timing of such rotation may be coordinated with the addition of each object to the stack so that as the object is dropping onto either support plate  206  or the objects already stacked on support plate  206 , support plate  206  is not rotating. In other words, support plate  206  is rotated between successive additions of objects to the stack. 
         [0058]    In other embodiments, rotation of support plate  206  is continuous during stack formation. Once rotation begins either before or after the first object comes to rest on support plate  206 , support plate  206  rotates continuously until the stack is complete. 
         [0059]    Stack rotation can be directed by a user-managed controller. This may provide options to the user as to whether rotation is continuous or incremental. Additionally, the controller may allow the user to choose a rate of continuous rotation, an extent of incremental rotation, as well as other characteristics of the rotation. 
         [0060]    The vertical motion of the linearly movable portions of stack support  200  may also be subject to user control. This may include the rate of vertical displacement, the extent of vertical displacement for each object added to the stack, whether such vertical displacement is fixed or based on the current height of the stack of objects or a position of a top of the stack of objects relative to input conveyor  100 , and other features. 
         [0061]    While exemplary embodiments have been described, it is understood that other variations and embodiments are possible within the spirit and scope of the invention, the scope of which is defined by the appended claims.