Patent Publication Number: US-6666006-B2

Title: Sheet feeder and sealer for automatic slicing machine

Description:
FIELD OF THE INVENTION 
     The present invention relates to an automatic slicing machine. More particularly this invention concerns such a machine which is equipped to wrap and seal the slices. 
     BACKGROUND OF THE INVENTION 
     A standard slicing machine has an input table that can be reciprocated longitudinally past a normally circular rotating blade to cut slices from a foodstuff, for instance a piece of meat or cheese, sitting on the input table. On the other side of the blade the slices are picked up by a conveyor, typically a fork-, belt-, or chain-type arrangement having a vertical support plate and provided with a multiplicity of sharp points so that the slices can be caught on the conveyor as they issue from the downstream side of the blade. A transfer fork has tines engaged between adjacent elements of the conveyor and can be pivoted to pull the slices off the conveyor and deposit them on an output table which is positioned horizontal underneath the downstream side of the blade. Thus as the input table is moved back and forth, slices are cut from the foodstuff thereon, these slices pass the blade and are picked up the conveyor, and the transfer fork deposits them in a stack on the output table. Such machines are described in detail in my earlier U.S. Pat. Nos. 4,185,527, 4,217,650, 4,338,836, 4,379,416, 4,586,409, 4,598,618, 4,763,738, and 4,867,257. 
     In order to separate the slices from each other, to separate groups of slices, and/or to form a package around the slices, it is known to insert underneath the stack, between the slices, and/or on top of the stack a sheet or foil. In one system a sheet is set on the conveyor before the stack is started so that the stack is formed atop this bottom sheet, then sheets are interposed between succeeding slices as they are deposited on the bottom sheet and on each other or are interposed after a certain number of slices corresponding to a standard portion has been deposited. A top sheet is deposited on top of the stack when the desired number of slices have been deposited. 
     The standard system for doing this has a supply, normally a roll, of the flexible strip from which the sheets are cut and a feeder that is typically a pair of pinch rollers that can be driven to pull the flexible strip from the roll. The end of the roll is pushed by the rollers out onto a flat table and a cutter slices off the end. Then a separate manipulator normally having a plurality of suction grippers picks the sheet formed by the cut-off end and deposits it on the conveyor where the foodstuff slices are stacked. 
     In commonly owned U.S. Pat. No. 6,279,302 a slicing machine that deposits foodstuff slices in a stack atop a support in a stacking station has a sheet-interposing device provided with a supply roll of flexible strip and a feed roller for feeding a leading end of the flexible strip in a direction to the stacking station. A guide between the station and the roller imparts to the sheet leading end an upwardly concave U-shape to stiffen the sheet leading end so it projects horizontally stiffly from the guide above the station. A cutter movable between the guide and the station cuts off the sheet leading end so that the cut-off end drops down in the station. 
     Thus the equipment can comprise, normally arrayed in a row or line, an upstream paper roll and feeder, a central slicing and arraying machine, and a downstream sealing machine. In many markets this equipment is intentionally set up so the customers can watch it work, assuring themselves at the same time that they are getting what they want, and that the foodstuff is being handled by the machine in a hygienic manner. All the operator needs to do is load in the piece of meat, wurst, cheese, or the like to be sliced, set the desired slice thickness, total weight, and array type, and the machine creates a sealed package for the customer. The machine is even known to be modular, so that the supply and sealing units can be taken off the slicing/arraying unit. As a result such machines are quite large. 
     OBJECTS OF THE INVENTION 
     It is therefore an object of the present invention to provide an improved automatic slicing and packaging machine. 
     Another object is the provision of such an improved automatic slicing and packaging machine which overcomes the above-given disadvantages, that is which can produce a sealed package but that is of a relatively small footprint. 
     SUMMARY OF THE INVENTION 
     A slicing machine has according to the invention a main housing having a horizontal conveyor surface and a subassembly in the main housing for cutting slices from a foodstuff and depositing them on the conveyor surface. A supply housing immediately upstream of the main housing carries a supply roll of flexible strip and mechanism for feeding the flexible strip downstream toward the main housing. A cutter on the supply housing can sever a sheet from a leading end of the flexible strip. In accordance with the invention a gripper above the surface is displaceable between an upstream position generally at the cutter and a downstream position downstream of the surface. The gripper is closable to grip the leading end of the flexible strip and openable to release it. A controller connected to the gripper, to the cutter, and to the supply periodically displaces the gripper between its upstream and downstream positions so as to pull the strip downstream above the surface, operates the cutter to sever a sheet from the downstream strip end generally when the gripper reaches its downstream position, and opens the gripper in the downstream position to drop the sheet severed from the strip down onto the surface. 
     Thus with this system the supply housing carries the roll of flexible strip as well as the mechanism for feeding it and the cutter. These elements are mounted on a separate housing that fits right against the main housing having the cutting/arraying subassemblies so that the entire machine according to the invention is relatively compact. 
     In accordance with the invention the supply housing and main housing are provided with interfitting formations that hang the supply housing on the main housing. Thus the supply housing can be unhooked and taken away when the main housing and its elements need cleaning, which is particularly advantageous since the supply housing never touches the food stuff and stays quite clean. 
     Furthermore, a drive on the main housing includes a drive wheel exposed at an upstream end of the main housing, a drive wheel exposed at a downstream end of the supply housing, engaging the main-housing drive wheel, feed rollers on the supply housing engaging the flexible strip, and a transmission connecting the supply-housing drive wheel with the feed rollers and with the gripper for synchronous movement. Thus when the supply housing is hung on the main housing, the mechanical connection is made to the supply mechanism, eliminating the need for a separate drive for this part. The cutter on the other hand includes an electrically powered actuator and electrical contacts connected to the actuator and exposed on a downstream end of the supply housing. Control contacts on an upstream end of the main housing engage the supply-housing contacts when the supply housing is hung on the main housing to supply low voltage to the actuator, normally a solenoid, to operate it. 
     The gripper according to the invention has a pair of relatively movable jaws oppositely engageable with the flexible strip. A spring urges them together and cams are effective to spread them to grasp and release the leading end of the flexible strip. 
     According to the invention a sealer housing is provided immediately downstream of the main housing, elements in the sealer housing seal sheets of the flexible strip around slices produced by the cutter. A conveyor on the main housing forms the surface, and a drive motor in the sealer housing is connected to the conveyor in the main housing. In this system the controller is in the main housing. The connection is made by contacts like for the actuator of the cutter. 
     The sealer in accordance with the invention further includes a short conveyor forming an extension of the conveyor surface of the main housing, an upper heated annular die above the short conveyor, and an actuator controlled by the controller for raising the short conveyor and a slice stack thereon up into engagement with the die to fuse sheets underneath and on top of the stack together. Thus the system has on a separate housing, which also never directly contacts the foodstuff being packaged, all the parts for sealing the package made up on the middle main housing. 
     According to the invention a smoothing element connected to and movable upstream and downstream with the gripper is engageable downwardly with slices on the conveyor surface. A cam on the main housing raises the smoothing element as the gripper travels from the upstream to the downstream position and lowers it when moving from the downstream to the upstream position. A two-arm lever pivoted on the gripper has one arm carrying the smoothing element and another arm engageable with the cam. A spring urges the other arm into engagement with the cam. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which: 
     FIG. 1 is a partly diagrammatic small-scale sectional side view of the machine according to the invention; 
     FIG. 2 is a side view of the machine; 
     FIG. 3 is a top view of the machine; and 
     FIGS. 4 through 8 are largely diagrammatic side views illustrating a system for smoothing the cover sheet. 
    
    
     SPECIFIC DESCRIPTION 
     As seen in FIGS. 1 through 3 a slicing/packaging machine  1  according to the invention has a main housing  14  flanked on its upstream side by a feeder housing  13  and on its downstream side by a sealer housing  27 . An upwardly projecting lip  54  on the housing  13  allows it to be hung in a downwardly open slot  33  of the housing  14  while the housing  27  normally stands adjacent this housing  14 . 
     The main housing  14  carries a slide or carriage  2  adapted to hold a foodstuff  3 , here a wurst, which is pressed against a stationary abutment plate  4  and moved past a standard circularly planar blade  5  to cut slices  46  (FIGS. 4-8) from it. Point-carrying feeder chains  6  carried on a frame  7  moved by a controller  8  deposit the slices as shown by arrow  11  on a horizontal deposition/conveyor surface formed by a belt  10  also operated by the controller  8 , the slices dropping into an array which may be a simple stack or extended in two directions depending on how the controller  8  moves the belt  10 . The above-cited patents describe systems for controlling the array the slices are deposited in. 
     The supply housing  13  carries a roll  12  of a flexible strip  23 , normally plastic or plastic-coated paper, on a pair of rollers  18  at least one of which is driven by a belt  50  from a gear  16  projecting downstream (to the right in FIGS. 1-3) from the housing  13  and meshing with a gear  15  projecting upstream from the housing  14  and driven by a motor  17  operated by the controller  8 . The strip  23  issuing from the roll  12  moves downstream and through a pair of pinch rollers  19  driven by a belt  51  from the drive gear  16 . In addition the housing  13  carries a standard two-blade cutter  25  immediately downstream of the pinch rollers  10 . The cutter  25  is closed by a solenoid  26  operated by the controller  8  and can sever a sheet  47  off the downstream end of the strip  23  as will be described below. Contacts  57  on the housings  13  and  14  bear against each other with spring force to supply voltage to the solenoid  26  when the housing  13  is hung on the housing  14  by the formations  33  and  54 . 
     The main housing  14  carries a gripper or feeder bar  20  formed as a rack meshing with a gear  21  driven by the belt  51  and having a fixed jaw  22  and a movable jaw  52  both movable horizontally level with the strip  23  coming off the supply roll  12 . A spring  53  normally holds the jaws  22  and  52  together, but, when the rack bar  20  is in a fully downstream position as illustrated in FIG. 1, the jaw  52  engages a fixed abutment  24  and is pivoted away from the jaw  22 . Another such abutment is provided to open and then close the jaws  22  and  52  as they move into an upstream end position (dashed lines in FIG. 1) of the feeder bar  20 . 
     The sealer housing  27  has a belt  28  carried on a frame  29  raisable by an actuator  30  and a motor  9  that connects to the downstream end of the conveyor  10  and that is in turn operated by the controller  8 . Above the belt  28  is an annular electrically heated welding frame or die  31  which, when pressed around a stack of slices sitting on a weldable sheet and covered by a weldable sheet, can weld the sheets together to seal in the slice stack as described below. An unloading conveyor  32  leads down and away from the conveyor  28  in its lower illustrated position. 
     The above-described machine  1  works as follows: 
     A foodstuff  3  is set on the table  2  and the machine  1  is set for the desired slice thickness, package weight, and slice array. At this time the feeder bar  20  is all the way to the left, that is in its most upstream position, and its jaws  22  and  52  are gripping the leading edge of the flexible strip  23 . 
     At first the drive  17  is operated by the controller  8  to simultaneously rotate the supply roller  12 , turn the pinch rollers  19 , and retract the bar  20  downstream so as to pull the flexible strip  23  straight downstream from the supply roll  12 . The peripheral speeds of the rollers  18  and  1  are identical to the linear displacement speed of the bar  20  to keep the strip  23  taut. Once the bar  20  comes to the solid-line downstream position, the abutment  24  opens the jaws  22  and  52  and the controller  8  cycles the cutter  25  to cut a sheet  47  from the leading end of the material  23 . This severed and released sheet  47  will drop down onto the support belt  10 . 
     Then the controller  8 , as is well known in the art, reciprocates the table  2  past the blade  5  and operates the stacking belts  6  to form a stack or array of slices  46  (FIG. 4) atop the sheet  47 . This array can be a simple stack of superpositioned slices or can be a row of offset slices or even a two-dimensional, e.g. spiral, array. During this slicing and arraying operation the jaws  22  and  52  stay in their downstream position and the rollers  18  and  19  are stationary. 
     Once the desired number of slices  46  has been dropped atop the bottom sheet  47 , the drive  17  advances the strip  23  somewhat so it projects past the cutter  25  and the bar  20  is advanced back upstream (to the left in FIG. 1) and its jaws  22  and  52  are opened and closed on the projecting leading end of the strip  23 . Then the drive  17  is operated to pull another section of the material  23  out and cut off another sheet  48  that is dropped atop the stack as described above at the start of operation. The gear  16  is connected to the rollers  18  and  19  via unillustrated one-way clutches, so that when the gear  15  is reversed the bar  20  is pulled back, but the strip  23  is not wound back up on the roll  12 . 
     This stack of slices  46  sandwiched between two sheets  47  and  48  is then displaced downstream by the conveyor  10  and onto the synchronously moving conveyor  28  that runs until the stack is exactly centered under the sealing die  31 . The actuator  30  then lifts the frame  29  to press the edges of the two sheets  47  and  48  together, thereby sealing in the stack. 
     Thereafter the frame  29  is dropped back down to the illustrated lower position and the two belt conveyors  28  and  32  are operated to carry off the sealed product. 
     FIGS. 4 through 8 show a system for smoothing a top sheet  48  over a stack of slices  46 . One or more soft rollers  40  are pivoted about a horizontal axis  41  on one arm of a two arm lever  42  whose other arm carries a roller  43  urged by a spring  44  down against a cam  45 . This arm  42  is itself pivoted on an upstream side of the bar  20  carrying the gripper jaws  22  and  52 . 
     The cam  45  comprises a stationary upper part  55 , an upwardly arcuate lower part  56 , and an upwardly pivotal flap  49  normally closing a gap at an upstream end of the part  55 , a similar gap at the downstream end always being open. Thus as the bar  20  moves the lever  42  downstream, the roller  43  will initially as shown in FIG. 5 ride atop the parts  49  and  55 , holding the smoothing rollers  40  up and out of contact with the package on the conveyor  10 . Once, however, the roller  43  drops off the end of the part  55  as shown to the right in FIG. 5, the lever  42  pivots down and, as the lever  42  is moved back upstream as shown in FIGS. 6 and 7, the rollers  40  ride on the package and flatten and smooth out the top sheet  48 , eliminating any bubbles from it and largely squeezing the air out of the package. 
     Once the roller  43  comes to the upstream end of the lower part  56  of the cam  45  as shown in FIG. 8 it rises up, thereby lifting the rollers  40  and coming out past the flap  49  so that it returns to the position of FIG.  4 . Since the rollers  40  only contact the top sheet  48 , they will remain clean.