Abstract:
An automated pretzel forming machine that produces fresh unbaked pretzels with hand formed characteristics by extruding premixed dough onto a folding table. This table is moved by a bi-directional positioning stage, forming the unfolded and untwisted pretzel shape. The folding table twists the ends of the extruded dough rope then folds the twisted portion on top of the main body of extruded dough resulting in the classic hand twisted pretzel shape. The twisted and folded pretzel is transferred from the folding table through the use of a lift and rotate unit and is subjected to a patterned soda spray and salted before being unloaded from the lift and rotate unit to an existing conveyor oven.

Description:
BACKGROUND OF THE INVENTION 
     The current invention addresses the need for automatic pretzel making machinery that forms larger sized pretzels into the classic pretzel shape. The method shown offers a unique way of forming any size pretzel, however our development focus was production of larger gourmet pretzels. There has been much work in the so-called bulk bag bite size pretzels commonly sold in the grocery stores. However many of these production machines do not form the classic pretzel shape. The present invention automates the forming of the pretzel into the classic “child with folded praying arms shape” attributed to circa 610 AD. Because of the difficulty in forming this classic shape, many current automation techniques for bulk pretzel manufacture alter or simplify the shape of the pretzel to achieve the required production rates and capital costs. 
     The majority of the prior art and inventions cited offer methods, which are not the classic pretzel shape. Of the patents cited, the only ones which wind up with the classic shape are U.S. Pat. Nos. 5,766,663, 5,702,732, 5,556,660, 5,494,428, and 5,009,910. These cited patents use vastly different methods, some more suited to bulk manufacture of smaller pretzels, and some require large capital outlays because of the complexity of the equipment. Also if these cited methods were scaled up to produce the larger gourmet pretzels the resulting floor space and investment in capital equipment make these machines unusable for many point of sale production facilities. Prior art also cited in U.S. Pat. Nos. 4,894,002 and 4,536,147 use an extruder to present the dough and some type of X-Y movement which limits the movement to produce only an altered pretzel shape. 
     The present invention combines modern automated forming techniques, which results in greater consistency of product, speed of production, with the classic 610 AD “hand formed” pretzel shape. 
     SUMMARY OF THE INVENTION 
     It is a general object of the present invention to provide a machine that takes raw pretzel dough and produces a salted unbaked pretzel with the same characteristics as if it were hand formed. 
     It is another object of the present invention to provide a machine that produces pretzels for point of sale production facilities. That is, the machine is to be compact in size and easy to disassemble and reassemble for daily cleaning 
     It is further the object of the present invention to provide a machine that produces fresh pretzels with hand formed characteristics at a faster rate than if made by hand. 
     In accordance with the present invention, the hand formed characteristics are achieved through the use of a unique folding table onto which raw dough is extruded and the dough rope shaped through bi-directional motion of the folding table on a bi-directional positioning stage. The folding table also twists the dough then folds it resulting in a pretzel with hand formed characteristics. The raw dough pretzel is subjected to a soda water spray and salting before being unloaded from the machine into a conveyor oven. The application of the soda water causes the pretzel to brown when baked in the oven. Also in accordance with the present invention, all parts that come in direct contact with food items are easily disassembled with no tools for daily cleaning. 
     The above and other objects, features, and advantages of the present invention will be apparent in the following detailed description of the preferred embodiment when read in conjunction with the accompanying drawings wherein the same reference numerals denote the same or similar parts throughout the several views. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated herein and form a part of the specification illustrate preferred embodiments of the present invention, and together with the description, serve to explain the principles of the invention. 
     FIG. 1 is a plan view of the present invention with the extruder drive belt cassette and motor removed for clarity. 
     FIG. 2 is a side elevation of the present invention. 
     FIG. 3 is a plan view of the folding table on the X-Y positioning stage. 
     FIG. 4 is a side elevation of the folding table on the X-Y positioning stage shown in the middle of the twisting process. 
     FIG. 5 is a rear elevation of the folding table on the X-Y positioning stage illustrating the pretzel twisting process. 
     FIG. 6 is a side elevation of the folding table on the X-Y positioning stage showing the pass through flipper during the pretzel folding process. 
     FIG. 7 is a rear elevation of the lift and rotate transfer table. 
     FIG. 8 is a side elevation of the lift and rotate transfer table. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1,  2 , and  3 , the extrusion portion of the pretzel making process begins by placing pre-mixed, unbaked pretzel dough into the dough bin  1 , which is bolted to the extruder frame  2 . The dough is fed to the extruder  6  by means of a flat plate dough pusher  3  located inside the dough bin  1 . The dough pusher  3  is moved using a lead screw  4 , also located in the dough bin  1 , and a nut  89  welded to the dough pusher. The lead screw  4  is powered by an electric motor  5  mounted to the extruder frame  2  and a drive belt  100 . The dough is forced through the extruder nozzle  9  by means of an auger (not shown) located inside the extruder  6 . The extruder  6  is powered by an electric motor  7  mounted to the extruder frame  2 . Power is transferred from the motor  7  to the extruder  6  using a removable drive belt cassette generally shown as  8 . The drive belt cassette  8  is a self contained unit comprised of an aluminum housing  79  which contains the motor pulley  81 , the extruder pulley  80 , the belt tensioner pulley  82 , the belt tensioner spring  83 , and the drive belt  84 . The extruder pulley  80  is attached to the extruder shaft  85  and the motor pulley  81  is attached to the motor shaft  86 . Power is transferred from the motor pulley  81  to the extruder pulley  80  through the drive belt  84 . Drive belt tension is maintained by the belt tensioner spring  83  applying constant force on the belt tensioner pulley  82 . Both the extruder shaft  85  and the motor shaft  86  protrude from the cassette housing  79  and have square holes on their protruding ends. The square hole of the extruder shaft  85  fits over the square portion of the auger shaft (not shown) which extends out from the extruder  6  in the Z direction on the end opposite of the nozzle  9 . The square hole of the motor shaft  86  fits over the square portion of a motor shaft adapter  88  which is fastened to the extruder motor  7 . When the drive belt cassette  8  is set in place over the square ends of the auger shaft and the motor shaft adapter  88 , it is held in place on the extruder frame  2  by means of two hold down toggle clamps  87 . This set up allows for easy removal and replacement of the entire drive belt system without any tools so that the baking staff can have daily access to the dough extruder system for cleaning. 
     The dough is extruded through the nozzle  9  and on to a slotted table  10  and in to the y-shaped hollowed out portion of one of the dough twist stabilizer inserts  13  forming the first stage of the pretzel shape  98 . The first stage of the pretzel shape  98 , best seen in FIG. 3, consists of a round section of the extruded dough rope with its ends crossed into a y-shaped pattern. The y-shaped portion of the extruded dough rope  98 , with one end passing over top the other, provides the first half of the twist. The slotted table  10  and the dough twist stabilizer insert  13  are part of the folding table unit generally shown as  90 . The components of the folding table unit  90  are held in place between the two folding table side plates  31 . To achieve the first stage of the pretzel shape  98 , the entire folding table unit  90  is moved in the X and Y directions as the dough is extruded through the nozzle  9 . The folding table unit  90  is fastened to the Y-direction base plate  22  to obtain its motion in the Y-direction. There are four linear bearings  25  fastened to the Y-direction base plate  22  which slide along two parallel shafts  23 . Shaft holders  24  support the two parallel shafts  23  at both ends. Motion in the Y direction is provided by a lead screw  26  and the lead screw nut (not shown) which is attached to the bottom of the Y-direction base plate  22 . The lead screw  26  is powered by the Y-direction stepper or servo motor  28  and is coupled to the motor by the stepper or servo motor coupling  29 . The lead screw  26  is supported at both ends by plain bearings (not shown) and the lead screw holders  27 . To obtain its motion in the X-direction, the folding table unit  90  and the Y-direction portion of the positioning stage are fastened to the X-direction base plate  14 . The Y-direction linear shaft holders  24  and the Y-direction lead screw mounts  27  are fastened to the top of the X-direction base plate  14 . There are four linear bearings  17  fastened to the bottom of the X-direction base plate  14  which slide along two parallel shafts  15  in the X direction. Linear shaft holders  16  support the two shafts  15  at both ends. The X-direction lead screw  18  and the lead screw nut (not shown) which is fastened to the bottom of the base plate  14 , provide the means for moving the folding table unit  90  in the X-direction. The X-direction lead screw  18  is supported at both ends by plain bearings (not shown) and the lead screw mounts  19 . The X-direction stepper or servo motor  20  provides power to the lead screw  18  and is coupled to it by the X-direction stepper or servo motor coupling  21 . When the required amount of dough has been extruded into the first stage of the pretzel shape  98 , the dough cutter solenoid  11  is activated and the dough cutter knife (not shown) slides through knife blade support  12  cutting the dough rope off just under the extruder nozzle  9 . 
     Referring to FIGS. 3-6, once the dough has been extruded and the dough rope cut off at the nozzle, the folding table unit  90  and the X-Y positioning stage move to the maximum distance in the negative Y direction to begin the twisting and folding process. During the extrusion process, part of the dough is extruded into the y-shaped hollowed out portion of the dough twist stabilizer insert  13 . The y-shaped groove in the insert  13  and opposing insert  32  accommodates the y-shaped portion or tail of the extruded dough rope  98  and is as deep as half the thickness of the dough rope. The insert  13  rests on the stabilizer insert frame  33 , which is coupled to the twist stabilizer stepper motor  35 . To begin the twisting process, the opposing twist stabilizer frame  34  and insert  32  rotate 180 degrees and close over top of the y-shaped portion of the extruded dough shape  98 , the other twist stabilizer insert  13  and frame  33 . The opposing twist stabilizer stepper motor  36  powers the opposing twist stabilizer frame  34  and insert  32 . When in the closed position, the y-shaped portion of dough is totally enclosed between the two stabilizer inserts  13  and  32  which allows the extruded dough  98  to maintain its shape as it is twisted. The stabilizer inserts  13  and  32 , the stabilizer insert frames  33  and  34 , and the twist stabilizer stepper motors  35  and  36  are attached to the twist yoke  37  which allows them to rotate with the yoke  37  as the dough is twisted. With both halves of the twist stabilizer enclosing the y-shaped portion of dough, the twist yoke  37  is rotated 180 degrees, giving the dough a total of one full twist. This is best seen in FIG.  5 . Attached to the twist yoke  37  is the twist yoke shaft  91 , which extends into the twist motor housing  40  through two plain bearings (not shown). The twist motor housing  40  is fastened to the Y-direction base plate  22 . The twist yoke stepper motor  38 , which is mounted to the twist yoke housing  40  powers the twist yoke  37 . There is a pulley  41  fastened to the twist yoke stepper motor  38  and another pulley  42  fastened to the twist yoke shaft  91 . Power is transferred from the stepper motor  38  to the twist yoke  37  through the drive belt  39 . 
     After the dough is twisted, the stabilizer insert  32  and frame  34  which had closed over the top of the dough is now on the bottom and the stabilizer insert  13  and frame  33  are now on the top. The twist stabilizer stepper motor rotates the stabilizer insert  13  and frame  33  180 degrees opening the enclosed portion of dough. This final position for the stabilizer insert  13  and frame  33  and stabilizer insert  32  and frame  34  will be the starting position for the next pretzel to be made. With the stabilizer inserts and their corresponding frames in the open position, the twisted pretzel dough is ready to be folded. The pass through flipper  43  is powered by the flipper stepper motor  44  mounted to the folding table side plate  31 . The pass through flipper  43  rotates counter-clockwise 75 degrees to make contact with the stabilizer insert  32 . Once contact has been made, the pass through flipper  43  lifts the stabilizer insert  32  out of the stabilizer insert frame  34 . The pass through flipper  43  and the stabilizer insert  32  continue to rotate together through 150 degrees folding the twisted Y-shaped portion of dough laying it on top of the remaining portion of the extruded dough shape. This is best shown in FIG.  6 . The folding process gives the final pretzel shape  99 . The pass through flipper  43  and the stabilizer insert  32  then rotate clockwise 150 degrees setting the insert  32  back in its frame  34 . The pass through flipper  43  continues to rotate clockwise 75 degrees back to its original position. Once the pretzel folding process has been completed, the entire folding table unit  90  is moved by the X-Y positioning stage to its maximum position in the positive X direction triggering the limit switch  30 . 
     Refer to FIGS. 1,  2 ,  7 , and  8 . As the folding table unit  90  is moved in the X direction to the pick up position, the forks  45  of the lift and rotate unit, generally shown as  92 , slide into the slots on the slotted table  10  under the folded pretzel  99 . This will allow the lift and rotate unit to pick up the pretzel  99  and rotate it to the next station. To lift the pretzel  99 , the lift solenoid  52  is activated which causes the toggle linkage  53  to exert an upward force on the lift collar  54 . Resting on the lift collar  54  is the thrust bearing  55  and fork unit  46 . The lift collar  54 , thrust bearing  55 , and the fork unit  46  all slide in the Z-direction on the spindle  47 . The fork unit  46  holds both sets of forks  45 , which are the parts that actually touch the pretzel  99  when the pretzels are moved from station to station. The thrust bearing  55  allows the fork unit  46  to rotate with the spindle  47  even when in the lifted position. The top portion of the spindle  47  is square and fits through a square hole in the fork unit  46 . This allows the spindle  47  to drive the fork unit  46  as it rotates on the thrust bearing  55  and also allows the fork unit  46  to be removed with no tools for cleaning. The spindle  47  rotates inside 2 plain bearings  56 , which are held in place by two component hangers  57  that are fastened to the lift and rotate housing  60 . The electric motor  48 , fastened to the housing  60 , provides power to the spindle  47 . A pulley  50  is fastened to the spindle  47  and another pulley  49  is fastened to the motor  48 . Power is transferred from the motor to the spindle through the drive belt  51 . The rotational position of the forks  45  and fork unit  46  is provided by a four position cam  59  fastened to the spindle  47  and a limit switch  58  fastened to the housing  60 . The four position cam  59  activates the limit switch  58  in four positions 90 degrees apart signaling four different stations. 
     When the forks  45  lift the pretzel  99  from the slotted table  10  of the folding table unit  90 , it rotates counterclockwise 90 degrees to the salt and soda spray station, generally shown as  94 . Once the pretzel  99  is rotated under the salt shaker frame  61 , it is subjected to a patterned spray of soda water from the soda water spray nozzle  70 . The soda water pump  67  pumps the soda water solution from its container  66  through the inlet hose  68  and to the outlet hose  69 . The outlet hose is connected to a small pipe  95 , which runs to the spray nozzle  70  providing the patterned soda water spray. Any over spray and excess soda water on the pretzel  99  land in the salt and soda water catch pan  71 . After the pretzel  99  receives the soda water spray, the salt shaker vibrator  63  is activated and the pretzel  99  is salted. The baking staff loads salt into the salt bin  62 , which is mounted on top of a perforated sheet  64 . The vibrator  63  is also mounted on top of the perforated sheet  64 . When the vibrator  63  is activated, it forces salt to shake through the holes of the perforated sheet  64 . Any excess salt that does not stick to the pretzel  99  falls into the salt and soda water catch pan  71 . The perforated sheet  64  is mounted to the salt shaker frame  61  with vibration mounts  65 . This isolates the vibration from the salt shaker frame  61  and the rest of the machine. 
     When the pretzel  99  is finished being salted, the forks  45  rotate counterclockwise another 90 degrees to bring the pretzel  99  to the unload conveyor generally shown as  96 . The unload conveyor  96  is comprised of the conveyor frame  72 , which holds the conveyor belt roller  74  and the conveyor belt drive pulley shaft  75 . A series of o-ring conveyor belts  73  run between the conveyor belt roller  74  and drive pulley shaft  75 . The conveyor motor  76  powers the conveyor drive pulley shaft  75 . The drive pulley shaft  75  is driven by the motor shaft  97 , which is fastened to the motor  76 . The motor shaft  97  is slotted on one end, which fits over a flat on the drive pulley shaft  75 . This allows the entire unload conveyor  96  to easily be removed for cleaning while the stepper motor  76  and motor shaft  97  remain fastened to the machine. To remove the unload conveyor  96 , the flat on the drive pulley shaft  75  and the slot on the motor shaft  97  must be perpendicular to the X-Y plane and gives two possible shaft positions 180 degrees apart for removal. For the machine to sense that the motor shaft  97  and the drive pulley shaft  75  are in the right position, a two position cam  78  is fastened to the motor shaft  97 . The cam  78  will activate a limit switch  77  in two positions 180 degrees apart to signal if the unload conveyor can be removed. 
     After the forks  45  rotate the pretzel  99  over the unload conveyor  96 , the lift solenoid  52  on the lift and rotate unit  92  retracts, lowering the pretzel  99  onto the o-ring conveyor belts  73 . The o-ring conveyor belts  73  are spaced so that the forks  45  can pass through them. The forks  45  also drop below the level of the o-ring conveyor belts  73  so that there is no longer contact between the forks  45  and the pretzel  99 . Once the pretzel  99  is resting only on the o-ring conveyor belts  73 , the conveyor stepper motor  76  is activated and the pretzel  99  is conveyed away from the forks  45  and to the conveyor of an impinger type oven or other suitable baking apparatus. After the pretzel  99  is unloaded, the lift solenoid  52  on the lift and rotate unit  92  is energized raising up the forks  45 . The forks  45  are then rotated counterclockwise 90 degrees to an idle station to possibly be used for additional condiment application. The forks  45  are again rotated counterclockwise another 90 degrees back to the starting position where the lift solenoid  52  retracts lowering the forks  45  to be ready to pick up the next pretzel from the slotted table  10 . 
     The fork unit  46  of the lift and rotate assembly  92  contains two sets of forks  45  that are 180 degrees apart. Both sets of forks  45  lift and rotate at the same time, allowing some events to be happening simultaneously. Unless there is a fourth station in use, these simultaneous events happen at the unload conveyor  96  and at the pretzel pick up at the folding table unit  90 . When the forks  45  are lifted to pick up the pretzel  99  off the slotted table  10 , the opposite set of forks  45  are lifting up past the o-ring conveyor belts  73  ready to rotate to the next station. The same is true when the forks  45  are lowered to enter the slots of the slotted table  10  and at the same time the opposite set of forks is setting the pretzel  99  down on the o-ring conveyor belts  73  to be unloaded.