Patty-Forming Apparatus Sheet Interleave System

Background Of The Invention

In many manufacturing applications, particularly in food processing, it is highly desirable to interleave the finished articles with thin, flexible sheets of paper, waxed paper, cellophane, plastic film, or other very thin, flexible material. For example, in packaging meat slices or hamburger patties, individual sheets of paper, waxed paper or like material inserted between adjacent pieces of meat prevent the meat from sticking together and preserve the integrity of the individual meat pieces. The same situation is presented with stacks of sliced cheese; the cheese slices tend to "grow" back together unless the slices are separated by sheets of thin, flexible material.

Often, in the basic processing equipment, there is some stage of operation at which the individual hamburger patties or other such articles traverse a given discharge path, usually terminating at a stacking position; the preferred technique is to suspend individual sheets of waxed paper or the like at some intermediate position on the path so that each article, moving along the path, picks up a sheet of paper and comes to rest in a stack in which the articles are interleaved one-for-one with the paper sheets.

U.S. Patents 3,126,683; 2,877,120; 3,675,387; 4,054,967; and 7,159,372 all describe variations of sheet interleaving machines. U.S. Patent 3,952,478 describes a sheet applicator for a patty-forming apparatus wherein the patty-forming apparatus includes a reciprocating mold plate that moves linearly from a fill position to a knock out position. At the knock out position, patties are removed from the mold plate in a downward direction though a discharge path. The sheet

applicator interleaves individual, thin, flexible sheets of paper, cellophane, plastic film or like material with a series of hamburger patties or like flat, relatively thick articles as the articles traverse the discharge path in sequential spaced relation to each other, the path terminating at a stacking position. The sheet applicator comprises a vacuum transfer shuttle which is reciprocally movable along a shuttle path between a sheet application position intersecting the article discharge path and sheet transfer position adjacent to, but spaced from the discharge path. The shuttle has a central opening which encompasses the article discharge path, through which one of the articles may pass freely, when the shuttle is in its application position. The shuttle also has a group of small vacuum grippers which are distributed around the peripheral edges of the central opening in the shuttle, just beyond the edges of an article passing therethrough.

The sheet applicator also has a sheet feeder which includes a two-suction cup releasable sheet holder means for depositing a single, thin, flexible sheet on the shuttle in registry with the shuttle vacuum grippers, whenever the shuttle reaches its sheet transfer position. Each thin, flexible sheet is of a size and configuration so as to cover all of the shuttle vacuum grippers.

The shuttle and the sheet feeder are mechanically linked to, and driven by, the mechanical system that drives the mold plate of the patty-forming apparatus. The shuttle and the sheet feeder are moved in synchronism with the mold plate, with movement of the articles along the discharge path and in synchronism with each other, so that the sheet holder means of the sheet feeder releases each sheet as it arrives at the transfer position

in registry with the shuttle vacuum grippers, and so that the shuttle is in its sheet application position each time an article moves therethrough.

This system has been successfully commercialized for many years as a part of the FORMAX F-26 food patty-forming machine, available from Formax, Inc. of Mokena, Illinois, U.S.A.

U.S. Patent 7,159,372 describes a patty forming apparatus sheet interleaving system that provides an increased flexibility of operation in that the sheet interleaving apparatus is not mechanically linked to the mold plate drive and is controllable by servomotors. This patent describes a two-suction cup sheet transfer device. The present inventors have recognized that it would be advantageous to provide an improved sheet interleaving apparatus for a patty-forming apparatus that had an increased flexibility of operation and reliability.

The present inventors have recognized that it would be advantageous to provide a substantially modular sheet interleaving apparatus that could be added to a patty-forming apparatus easily and cost effectively.

The present inventors have recognized that at higher production rates with a two suction cup sheet transfer system the unsupported portion of the sheet may curl under after being pulled from the hopper by the two suction cups and thereafter miss proper alignment on the vacuum bar. The present inventors have recognized that it would be advantageous to provide a sheet interleaving apparatus for a patty-forming apparatus that had an enhanced ability to transfer a sheet from a sheet hopper to a position on the vacuum transfer shuttle, particularly sheets of a reduced thickness and stiffness.

Summary Of The Invention

The present invention provides a new and improved sheet interleaving system and apparatus for interleaving individual thin, flexible sheets of paper, cellophane, plastic film, of like material with a series of relatively thick, flat articles such as hamburger patties, as the articles traverse a given discharge path.

The invention provides a sheet interleave system for a patty-forming apparatus, such as described in U.S. Patent 7,159,372, herein incorporated by reference, that includes a hopper for holding sheets, a shuttle, an enhanced sheet transfer device, at least one precise position controlled motor, and a drive train. The shuttle has a sheet- holding frame that is slidable between a sheet receiving position and a sheet dispensing position. The sheet transfer device has three or more suction cups, preferably four suction cups arranged in a grid pattern, for gripping each sheet from the hopper. The suction cups are moveable from a position to grip a sheet from the hopper to a position to place the sheet on the sheet holding frame. The precise position controlled motor is preferably a servomotor. The drive train is driven by the precise position controlled motor. The drive train can be configured as a system of pulleys, belts, chains, levers or any other known means of converting rotational input from a motor to useful movement of working implements. The drive train is mechanically connected to the shuttle and to the sheet transfer device to impart controlled motion thereto.

An exemplary embodiment uses two precise position controlled motors to drive the paper system. Two separate precise position controlled motors, such as servomotors, are used, with one motor driving the suction cup movements and the other motor driving the

shuttle movements. A precise and flexible control and coordination of the movements between the vacuum cups and the shuttle is made possible.

The servomotor or servomotors of the embodiment can control the motion of the paper system for the best paper pick-off and placement timing, regardless of the motion of the mold plate.

Regardless of the type of sheet interleave drive system, whether it be a mechanically linked system such as described in U.S. Patent 3,952,478, herein incorporated by reference, or a servomotor controlled system such as in U.S. Patent 7,159,372, herein incorporated by reference, the enhanced sheet suction cup gripping system utilizing four suction cups, one at each corner of a rectangular sheet, in encompassed by the present invention. It is also encompassed to utilize any other number of suction cups such as three or more that apply suction to a sheet along both an X axis and a Y axis on the plane of the sheet.

According to another aspect of the invention, the sheet interleave system comprises laterally arranged longitudinally extending rods, the rods having protruding ends arranged to be attached to an adjacent patty-forming apparatus and to support the sheet interleave system in cantilever fashion. The rods are also arranged to guide linear movement of the carriage. Particularly, a modified carriage attachment system can be utilized wherein carriage mounting adapter blocks are utilized to allow the sheet interleave system described in U.S. Patent 7,159,372 to be adapted to patty forming machines having mold drive bars such as found on a FORMAX F26 patty forming machine or an F26ULTRA patty forming machine such as described in U.S. Provisional Patent Application 60/881,877 filed January 23, 2007, herein incorporated by reference.

The sheet interleaving apparatus of the invention is reliable in operation and adaptable to use with a variety of sheets, patty shapes and processes. Because of the use of suction cups that grip the sheet along two axes X and Y, particularly by four cups in a grid arrangement, a reliable gripping and transfer of sheets is ensured. It may be possible to use thinner, less expensive sheets which otherwise would be too flimsy to be manipulated by a two-suction cup transfer device.

Numerous other advantages and features of the present invention will be become readily apparent from the following detailed description of the invention and the embodiments thereof, and from the accompanying drawings.

Brief Description Of The Drawings

Figure 1 is a diagrammatic side view of a sheet interleaving apparatus connected to a patty forming apparatus, showing the sheet interleaving apparatus of the present invention, with some components and/or panels removed for clarity; Figure 2 is a top plan view of the sheet interleaving apparatus of Figure 1 , with some components and/or panels removed for clarity;

Figure 3 is a diagrammatic sectional view taken generally along line 3-3 of Figure 1 , with some components and/or panels removed for clarity;

Figure 4 is a diagrammatic sectional view taken generally along line 4-4 of Figure 1 , with some components and/or panels removed for clarity;

Figure 5 is sectional view taken generally alone line 5-5 of Figure 2, with some components and/or panels removed for clarity;

Figure 6 is a similar view of the apparatus shown in Figure 5, showing further movement of sheet interleaving components;

Figure 6A is a plan view of a sheet dispensing components of the apparatus shown in Figure 6, with some components and/or panels removed for clarity; Figure 7 is a rear, fragmentary perspective view of the apparatus taken substantially from view 7-7 shown in Figure 1, with some components and/or panels removed for clarity;

Figure 8 is a fragmentary, sectional view taken generally along line 8-8 of Figure 6, with some components and/or panels removed for clarity; Figure 9 is a side perspective view of the sheet interleaving apparatus shown in

Figure 7, with some components and/or panels removed for clarity;

Figure 10 is a side view of an alternate embodiment feature of the present invention;

Figure 11 is a diagrammatic side view of a sheet interleaving apparatus connected to a patty forming apparatus, showing an alternate embodiment sheet interleaving apparatus, with some components and/or panels removed for clarity;

Figure 12 is a fragmentary, sectional view of the apparatus of Figure 11 , with some components and/or panels removed for clarity;

Figure 13 is an enlarged, fragmentary perspective view of the apparatus of Figure 11 ;

Figure 14 is an enlarged, fragmentary inside perspective view of the apparatus shown in Figure 11;

Figure 15 is a fragmentary reverse perspective view of the apparatus shown in Figure 14;

Figure 16 is an enlarged fragmentary inside front perspective view of the apparatus of Figure 11 ; Figure 17 is an enlarged, fragmentary inside rear perspective view of the apparatus of Figure 11 ;

Figure 18 is a fragmentary rear perspective view of an alternate embodiment sheet transfer device of the invention, shown in a sheet dispensing position;

Figure 19 is a fragmentary front perspective view of the alternate embodiment sheet transfer device of Figure 18;

Figure 20 a fragmentary rear perspective view of the alternate embodiment sheet transfer device of Figure 18, shown in a sheet place position;

Figure 21 is an enlarged, fragmentary sectional view of an alternate embodiment shuttle mounting arrangement taken generally along line 3-3 of Figure 1.

Description Of The Preferred Embodiment

While this invention is susceptible of embodiment in many different forms, there are shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated.

Figures 1 through 9 illustrate a sheet applicator 11 constructed in accordance with the teachings of this invention and connected to the output side of a food patty-molding machine 13.

The food patty-molding machine 13 may be any of the types conventionally used to mold and shape food patties. An example of one of these machines is a molding machine manufactured and sold by Formax, Inc. of Mokena, Illinois, known as a FORMAX F-26 patty forming machine, FORMAX F-26 ULTRA patty forming machine or a FORMAX MAXUM700 patty forming machine, or the patty-forming machines shown and described in U.S. Patent 3,952,478, or U.S. Patent 7,159,372, all herein incorporated by reference. The food patty-molding machine includes a multiple cavity mold plate 15 which reciprocates between a mold cover 17 and a top plate 19. The mold plate may be formed with a number of patty cavities 21. The machine shown in this example has four cavities which are circular in shape to form relatively thick, flat articles 23 such as hamburger patties, or the like. The cavity shape can also be square, unsymmetrical, irregular or any other desired shape. The food to be molded enters the cavities 21 through input passages (not shown) located in the top plate 19.

The mold plate 15 is moved in a reciprocal path by mold plate drive bars (not shown), located on opposite sides of the machine. The bars are driven in a reciprocal motion by a mechanism which is not shown, but would be housed within a lower base 27 of the apparatus 13.

The sheet applicator 11 includes a vacuum transfer shuttle 41. The vacuum transfer shuttle 41 includes a sheet-receiving vacuum bar 51 which extends between, and is fastened to, shuttle carriages 53a, 53b via mounting plates 54a, 54b. The shuttle

vacuum bar 51 defines openings 55 in the shuttle 41. Suction grippers 57 are located on the upper surfaces of the vacuum bar 51 and more or less surround the periphery of each opening 55. The suction grippers 57 are formed by outlets connected to vacuum channels 59 extending within the vacuum bar 51, such as shown in Figure 6 of U.S. Patent 3,952,478. The vacuum channels 59 are connected at inlets 61 to vacuum supply lines 63.

The vacuum bar 51 is connected to a vacuum pump 65, preferably, a non-rotating, compressed air driven type, induced vacuum "pump" or vortex vacuum system. Vacuum lines 63 leading from opposite ends of the vacuum bar 51 connect to a solenoid operated valve 66 that controls the input line to the vacuum pump 65. The solenoid operated valve is controlled by the machine control 68 with positional input from the servomotor 200 as described below.

The vacuum grippers 57 are grouped in sets of four to form rectangular configurations spaced along the length of the vacuum bar 51. Each rectangular configuration of vacuum grippers surrounds one opening 55 of the vacuum shuttle. The location of the vacuum grippers 57 thereon are such that the vacuum grippers and projections will support the corners of thin, flexible sheets 83 placed on the vacuum shuttle 41 while allowing passage of thick, flat articles 23 produced by the food patty- molding machine 13 through the openings 55. A sheet feeder 91 is equipped with a number of inclined hoppers 93, one for each patty cavity 21 in the mold plate 15. The sheet feeder 91 of the type described herein is available from Formax, Inc., as part of a FORMAX F-26 patty-forming machine with a sheet interleaving apparatus.

In this embodiment, there are four hoppers 93, corresponding to the four food patty cavities 21. A stack of thin, flexible sheets 83 are stored in each hopper with the sheets substantially standing on edge at an angle to vertical and held in the hopper by stops 95 located at each corner and on the sides of an open face 97 at the lower end of each inclined hopper. Blades 99 at the top and bottom of this open face 97 engage the top and bottom center of the end sheet 83. The feeder 91 includes handles 91a, 91b, 91c.

A sheet transfer mechanism is arranged for placing thin, flexible sheets 83 from the hoppers 93 onto the vacuum transfer shuttle 41 in alignment with the rectangular groupings of the vacuum grippers 57, to cover the openings 55. A number, in this case four, of releasable sheet holders or suction devices 103 each remove a single sheet 83 each cycle from a hopper 93 and deposit the sheets on the vacuum transfer shuttle 41. The sheet holders 103 each include a pair of suction or vacuum cups 105. The vacuum cups are formed of a soft flexible material, such as soft rubber. Each cup is mounted on the end of a common suction plate 107. The suction plate is clamped at opposite ends to a cross shaft 109. The suction cups 105 are spaced in pairs along the plate 107 so that two suction cups will engage each sheet 83 at the open face 97 of each hopper 93, with the suction cups contacting the bottom portion of the sheet 83, wherein each cup is located above the lower stops 95 and outwardly of the knives 99. The opposite ends of the cross shaft 109 are journaled in first free ends 110 of cranks 111a, 111b which are located on opposite sides of the apparatus 11 and configured in mirror image fashion across a vertical longitudinal center plane of the

apparatus 11. The middle portion of each crank 111a, 111b is fixed by being clamped to a shaft 113, which extends across the width of the apparatus 11.

At least one small sprocket or toothed pulley 117 is affixed to the cross shaft 109 near one end thereof. The sprocket or pulley engages a chain or toothed belt 119 which also extends around a larger sprocket or toothed pulley 121. The larger pulley 121 is journaled on the shaft 113 and is affixed to a plate 123. The plate 123 is fixed to a stationary portion 124 of the apparatus frame. The larger pulley 121 does not rotate.

Second free ends 130 of cranks 111 a, 111 b are each pivotally connected to one end of a iink 133a, 133b, respectively on opposite sides of the apparatus and configured in mirror image fashion. The opposite end of each link 133a, 133b is pivotafly connected to a respective shuttle carriage 53a, 53b on opposite sides of the apparatus and configured in mirror image fashion. The carriages 53a, 53b comprise a first block 135a, 135b, respectively, which first blocks are fastened to a respective longitudinal plate 137a, 137b. Longitudinal plates 137a, 137b are fastened to second blocks 139a, 139b, respectively. The block pairs 135a, 139a; 135b, 139b of the carriages 53a, 53b are slidable on slide rods 141a, 141b, respectively.

The slide rods 141a, 141b are also used to mount the sheet interleaving apparatus 11, in cantilever fashion, with knee braces 142a, 142b, to the patty-forming apparatus 13.

The suction for vacuum cups 105 is drawn through tubing 143 connected to each cup and to a manifold 145. The manifold 145 is connected by tubing 146 to a solenoid controlled valve 147 which is connected to the input side of vacuum pump 149. The vacuum pump 149 is preferably a non-rotating, compressed air driven type, induced

vacuum "pump" or vortex vacuum system. The solenoid controlled valve 147 is controlled by the machine controller 68.

The patty-forming machine provides a row of knock-out cups 161 mounted above the vacuum sheet applicator 11 with each cup aligned with a cavity 21 in the mold plate 15, when the mold plate is in its outwardly extended, knock out position. Upon downward movement, the cups 161 force the food articles 23 out of the cavities 21 of the mold plate. While following these paths, each food articles 23 moves through an opening 55 of the vacuum bar 51 , engages a sheet 83, and lands with the sheet on a conveyor 165 or on a previously deposited article 23 on the conveyor, forming a stack 25. At a select time, the conveyor 165 transports the stacked patties with interleaved sheets 83 to a discharge station.

During operation, the individual movements of the suction plate 107, the shuttle 41 and the mold plate 15 are substantially as described in U.S. Patent 3,952,478. However, in that patent, the movements of the suction cups, and the shuttle that transfers the sheets to the knock out station, are mechanically linked to the movement of the mold plate and the knockout cups. In contrast, the present invention provides a controllable drive for shuttle 41 and the suction plate 107 that mounts the suction cups, that is mechanically independent of the drive for the mold plate and knockout cups. Thus, although the suction plate 17, the shuttle 41, the knockout cups 161, and the mold plate 15 have like movements as the like components in U.S. Patent 3,952,478, according to the invention, movements of the sheet interleaving components can be precisely adjusted independent of mold plate movement and knock out cup movement. In this way, as long as the shuttle is in position for the stroke of the knock out cups, the movements of the suction plate 107

and the shuttle 41 can be optimized for conditions most favorable to successfully removing a row of single sheets from the sheet feeder and depositing the row of sheets on the shuttle 41.

According to the invention, a servomotor 200 drives the cranks 111a, 111 b which drive the shuttle 41 and the vacuum plate 107. The servomotor is preferably a 3000 rpm, 3.1 KW (about 4 HP) servomotor. The servomotor includes a built in resolver for precise positioning information and control. The servomotor 200 is enclosed in a housing 202 to protect the servomotor from moisture. The servomotor includes a gearbox 206 with a turn ratio of about 5:1. An output shaft 210 of the gearbox 206 is fixed to a toothed pulley 212. The output shaft 210 is journaled for rotation by a bearing 216 mounted on a sidewall 218 of the apparatus 11. The shaft 113 freely penetrates through the toothed pulley 121 and is journaled by a bearing 220 mounted to the sidewall 218. The shaft 113 is fixed to a toothed pulley 226. A toothed belt 230 wraps around the pulleys 212, 226. The pulleys 212, 226 have about a 2:1 turn ratio such that the overall turn ratio between the servomotor and the shaft 113 is about 10: 1.

In operation, the servomotor 200 rotates in one direction and then in the opposite direction, causing the shaft 113 to rotate the cranks 111a, 111b to swing the shaft 109 from the position shown in Figure 6 to the position shown in Figure 5. As the shaft 109 is swung the small pulley 117 rotates by force from the belt 119, and the suction plate 107 flips the suction cups 105. This displaces the suction cups 105 through the positions indicated as 105a to 105b (Figure 6) to 105 (Figure 5). Once the direction of rotation of the servomotor 200 reverses, the shaft 113 rotates to swing the shaft 109 from the position shown in Figure 5 to the position shown in Figure 6 and the suction cups 105

move through the positions 105 (Figure 5) to 105b to 105a (Figure 6). The position 105a of the suction cups corresponds to the sheets 83 being placed on the shuttle 41. The position 105 (Figure 5) corresponds to the sheet 83 being engaged by the suction cups while in the feeder 91. While the shaft 113 pivots to swing the shaft 109 from the position shown in Figure

6 to the position shown in Figure 5, the free ends 130 of the cranks 111a, 111b swing to pull the carriages 53a, 53b toward the patty forming apparatus 13 to place the vacuum bar 51 to the position wherein the openings 55 align with the knock out cups, beneath the knock out cups. The knock out cups can then be driven downward to dispense the sheets 83 from the vacuum bar 51. When the direction of rotation of the servomotor reverses, the free ends 130 of the cranks 111a, 111b swing back such that the sheets 83 taken from the feeder hoppers 93 by the suction cups 105 are placed on top of the now empty vacuum bar 51 which now registers with the suction cups at the position 105a (Figure 6). The servomotor is signal-connected to the machine control 68 for the patty-forming apparatus or can have its own control that communicates with the machine control 68. The timing and dwell of the servomotor at different stages of its rotation can be adjusted to optimize the process of removing a row of single sheets from the feeder hoppers 93 and depositing those sheets onto the shuttle 41 in reliable fashion.

The machine control, with positional input from the servomotor, controls the timing of the application of vacuum to both the manifold 145 for the suction cups 105, and the vacuum bar 51 for the grippers 57.

Figure 10 illustrates alternate components to the pulley 212, pulley 226, belt 230, and tensioner 231. According to this embodiments levers 302, 304 are respectively fixed

to the output shaft 210 of the gearbox 206 and the shaft 113. The gearbox can have a turn ratio of 10:1 and the levers 302, 304 pivot back and forth together via a link 306 which is adjustable.

Figures 11 through 17 illustrate an alternate embodiment sheet applicator 511. According to this embodiment, a first motor 516 drives the vacuum plate 107. A second motor 518 drives the shuttle 41.

The first motor 516 has an output shaft 516a that drives the shaft 113 that pivots levers 517a, 517b fixed on the shaft 113 that causes the belt 119 to pivot the small sprocket or toothed pulley 117 as described in the prior embodiment. The levers 517a, 517b are arranged the same as the previously described cranks 111a, 111b, except in this embodiment the levers 517a, 517b have no lower portion for reciprocating the shuttle. The second motor 518 has an output shaft 518a that is coupled to a transverse shaft 528 that is keyed to cranks 526a, 526b. The second motor 518 drives the shaft 528 to swing the cranks 526a, 526b. The cranks 526a, 526b are respectively connected to rods 530a, 530b that extend rearward and are attached respectively to the blocks 139a, 139b. Pivoting of the cranks 526a, 526b by the motor 518 drives the shuttle 41 on the slide rods 141a, 141b. The cranks 526a, 526b and the rods 530a, 530b and carriages 53a, 53b are arranged on opposite sides of the apparatus 511 in mirror image fashion across a longitudinal vertical center plane of the apparatus 511. Preferably, the first and second motors 516, 518 are precise position controlled motors, such as servomotors. The servomotors 516, 518 are signal-connected to the machine control for the patty-forming apparatus or can have its own control. The timing and dwell of the servomotors at different stages of their rotation can be adjusted to

optimize the process of removing a row of single sheets 83 from the feeder hoppers 93 and depositing those sheets onto the shuttle 41 in reliable fashion.

The machine control, with positional input from the servomotors, controls the timing of the application of vacuum to both the manifold 145 for the suction cups 105, and the vacuum bar 51 for the grippers 57.

The alternate embodiment of Figures 11-17 is different from the previously described embodiment in that a single precise position controlled motor is replaced by two motors that make the drive for the shuttle and the drive for the suction cups mechanically independent. Accordingly, the two drives can be precisely controlled by the machine controller to optimize their functioning depending on the circumstances such as paper type, machine output speed, etc. In other respects, the other parts of the alternate embodiment of Figures 11-17 operate in like fashion as the parts of the previously described embodiment.

Figures 18-20 show an enhanced sheet transfer mechanism 700 arranged for placing thin, flexible sheets 83 from the hoppers 93 onto the vacuum transfer shuttle 41 in alignment with the rectangular groupings of the vacuum grippers 57, to cover the openings 55. The mechanism is configured identically and operates identically to the heretofore described mechanism except as noted.

A number, in this case five, of releasable sheet holders or suction assemblies 703a, 703b, 703c, 703d, 703e each remove a single sheet each cycle from a hopper (not shown) and deposit the sheets on the vacuum transfer shuttle 41. The sheet holders 703a-703e each include four suction or vacuum cups 105 as described previously herein. Each cup is mounted on the common suction plate 107. The suction cups 105 are spaced

in grid patterns, squares or rectangles, along the plate 107 so that four suction cups will engage each sheet 83 at the open face 97 of each hopper 93, with the suction cups 105 contacting each comer of the sheet 83. In other words, rather than just contacting along the bottom of each sheet as shown in Figure 5, the cups 105 contact along both the bottom and top of the sheet, gripping along both the X and Y axes in the plane of the sheet 83.

Although four suction cups are shown, and positioned to grip the sheets at positions which define a square or a rectangle, other numbers of cups could be used to grip the sheets in a nonlinear fashion, such as three suction cups which are positioned to grip the sheet at positions which define a triangle in the plane of the sheet.

At higher production rates with a two suction cup system the unsupported portion of the sheet may curl under after being pulled from the hopper and miss the vacuum bar. The four-suction cup system prevents this phenomenon and may be particularly useful at fast operating speeds or where thin sheet stock is desired. Figure 21 illustrates an alternate mounting arrangement for the vacuum transfer shuttle 41. The vacuum transfer shuttle 41 includes the sheet-receiving vacuum bar 51 which is fastened to adapter blocks 802a, 802b. The adapter blocks 802a, 802b are fastened to the shuttle carriages 53a, 53b by fasteners 806 and cylindrical spacers 808. In this way, the vacuum bar 51 can be used for a patty forming machine which has left and right mold plate drive arms 810, 812 which would otherwise interfere with the mounting arrangement heretofore described.

From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be

IS

understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred.