Heatshrink apparatus for automatically packaging grocery articles
United States Patent Harkness et a1.  
 14 1 Apr. 29, 1975 1 1 HEATSHRINK APPARATUS FOR AUTOMATICALLY PACKAGING GROCERY ARTICLES [75] Inventors: Kenneth A. Harkness; D. Mark Kettunen; Paul E. Schirtzinger; Kenneth A. Vaught, all of Columbus. Ohio [73] Assignee: Kenneth Harkness a/k/a ldeanamics,  
 Columbus. Ohio [22] Filed: Mar. 7, 1974 [211 Appl. No; 449,054  
 Related U.S. Application Data 162] Division of Scr. No. 333,561. Feb. 20, 1973. Pat. No.  
 [52] U.S. C1. 219/388; 53/76; 53/391;  
 [51 1 Int. Cl F27b 9/06; 1365b 53/02 [58] Field of Search 219/214, 385. 388. 411,  
 [56] References Cited UNITED STATES PATENTS 3.108.173 10/1963 Barrett et a1 219/411 X 3.283.469 11/1966 McBrady et a1. 53/184 X 3.342.306 9/1967 Fabbri 53/182 X 3.399.506 9/1968 Howc,.1r 53/184 X 3.581.458 6/1971 Gustavson 53/30 Primary Examiner-Velodymyr Y. Mayewsky Attorney. Agent, or Firm-Frank H. Foster 1571 ABSTRACT A machine for automatically packaging heterogeneous grocery store articles in heat shrinkable, thermoplastic film. The machine has a loading station at one end and an endless conveyor having a series of loading zones which is advanceable in discrete loading zone increments along a treatment passageway. Upper and lower film feed rolls feed film ribbons above and below the articles when the film ends are anchored to the conveyor by grocery articles and the conveyor is advanced. When the conveyor is stopped. a welding and severing means at a downstream weld station descends to bond the film ribbons together and sever the covering film from the feeding ribbons. A carriage. on which infrared radiators are mounted at a further downstream shrink station, descends to shrink the film tightly around the articles during the next machine cycle. A subsequent cooling station permits sufficient heat loss for safe handling of the packages.  
 3 Claims, 12 Drawing Figures 145 &amp;  
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 PHENIEBAPRZQISIS SHEET 12GF 12 WNW  1 HEATSHRINK APPARATUS FOR AUTOMATICALLY PACKAGING GROCERY ARTICLES This is a division of application Scr. No. 333,561, filed Feb. 20, 1973, now US. Pat. No. 3,830,036.  
 BACKGROUND OF THE INVENTION This invention relates generally to packaging machines and more particularly relates to a machine which can be cooperatively situated at a check-out counter at a grocery store for automatically wrapping purchased articles in durable, protective and conveniently carryable packages.  
  In modern supermarket merchandising, great quantities and varieties of consumer articles are displayed in rows of display shelves. They are packaged in containers of many different types, sizes and shapes. Customers typically push a cart along these rows and select the articles they desire to purchase, placing them in the cart as they go. The cart of articles is brought to at check-out counter where an attendant tallies each article and slides it to a separate collection area. These articles are then .ifted and placed in paper bags either simultaneously by a second employee or by the same attendant after all articles have been tallied.  
  This checking out and packaging operation is the major source of problems, expenses and irritation for both the supermarket operators and their customers. These operations consume considerable time and require relatively large numbers of employees. The operations also constitute the major traffic delay or bottle neck in the supermarket operation.  
  Consequently, there is a need for a machine which can reduce the time and the cost of the check-out and the packaging operation in a grocery store or other similar operation selling heterogenenous articles, such as, for example, hardware or dry goods stores.  
  Additionally, the paper bags, traditionally used for packaging grocery articles, are limited in strength so that when fully loaded, they must be carried by being supported beneath the entire contents. Thus, filled grocery bags can not be gripped by a hand and carried with the arm in a more comfortable downwardly extended orientation. Paper bags instead require that an upturned palm be placed beneath the entire package with the arm extended horizontally forward.  
  Paper bags sometimes become moistened or wet from leakage of their contents, from being set upon a wet surface or from rain or snow. Such moisture immediately destroys their strength and their ability to contain the grocery articles resulting in inconvenient dropping and often breakage or spillage of their contents. Also, such paper bags offer little protection from rain or splashed water.  
  There is therefore a need for a grocery packaging machine which provides a package having improved durability, protectibility and comfortable and convenient gripping and carrying.  
 SUMMARY OF THE INVENTION The invention is an apparatus for packaging heterogeneous grocery articles and the like and has a support frame with a frontal, horizontal opening forming an unobstructed loading station above the opening. An article treatment passageway extends downstream through the frame from the loading station. An endless conveyor formed into an endless series of loading zones which are positionable beneath the loading station is drivingly advanceable in discrete loading zone increments downstream along the passageway. A film feed means feeds both a first film ribbon loosely onto the conveyor in a feeding direction past the loading station and a second film ribbon in unobstructive avoidance of the loading station downwardly to the first film ribbon. The film feed means is actuable to feed film when the film is anchored to the conveyor by articles and pulled by advancement of the conveyor. Mounted down stream of the loading station is a transverse welding and severing means for bonding the first film ribbon to the second film ribbon between loading zones and for severing the ribbons intermediate the bond. Further downstream is a heat shrink means for shrinking film posi tioned at a shrink station. A control means is provided for advancing the conveyor one loading zone incre ment in response to a momentary manual actuation and for controlling the operation of the heat shrink means and the welding and severing means.  
  It FDR an object of the invention to provide an improved article packaging machine.  
  Another object of the invention is to speed up and automate the packaging of grocery articles.  
  Another object of the invention is to provide an automatic packaging machine which permits grocery articles to be handled only once during the tallying process and avoids separate handling for packaging purposes.  
  Another object of the invention is to eliminate the need for a second employee to package grocery arti cles.  
  Another object of the invention is to provide a grocery article package which is easily gripped and carried in a comfortable manner, is water-proof for protecting its contents and doesnt weaken upon exposure to moisture.  
  Further objects and features of the invention will be apparent from the following specification and claims when considered in connection with the accompanying drawings illustrating the preferred embodiment of the invention.  
 DESCRIPTION OF THE DRAWINGS FIG. 1 is a pictorial view in perspective of an entire check-out packaging counter operation in a supermarket utilizing the automatic packaging machine of the present invention.  
  FIG. 2 is a view in perspective of the operating mechanisms of the preferred embodiment of the invention.  
  FIG. 3 is a diagrammatic view in side elevation of the working mechanisms of the preferred embodiment of the invention.  
  FIG. 4 is a diagrammatic view in side elevation illustrating the operation of the preferred embodiment of the invention.  
  FIG. 5 is a view in side elevation of the loading and welding station portions of the preferred embodiment of the invention.  
  FIG. 6 is a plan view of the same portion of the embodiment of the invention illustrated in FIG. 5.  
  FIG. 7 is an end view of the same portion of the embodiment of the invention illustrated in FIG. 5.  
  FIG. 8 is a view in side elevation of the remaining portion of the preferred embodiment of the invention including the shrink station and the exit package retaining station.  
  FIG. 9 is an end view of the same portion of the preferred embodiment of the invention illustrated in FIG. 8.  
  FIG. 10 is a top plan view of the same portion of the preferred embodiment of the invention illustrated in FIG. 8.  
  FIG. 11 is a schematic diagram of a portion of the control means circuit for operating the preferred em bodiment of the invention.  
  FIG. 12 is a schematic diagram of the remaining portion of the control means circuit for operating the preferred embodiment of the invention.  
  In describing the preferred embodiment of the invention illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended to be limited to the specific terms so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.  
 DETAILED DESCRIPTION FIG. 1 illustrates a typical grocery store installation including the preferred embodiment of the invention. This typical installation includes a check-out counter 10 and a packaging machine 12 constructed according to the present invention. Both are controlled by an attendant l4. Described very briefly and broadly, a customer with a grocery cart (not shown) filled with selected articles proceeds to the check-out counter 10 which is protected from moving grocery carts by a horizontal guard rail [6. The customer unloads the selected articles, indicated generally as onto a conveyor 22.  
  The attendant I4 individually tallies the articles in sequence either with automatic tally equipment as shown or with a conventional manual cash register and after doing so sets the tallied articles, indicated generally as 24 onto the loading station 26 of the packaging machine I2. When a suitably sized grouping of the tallied grocery store articles has been accumulated at the loading station 26, the attendant l4 momentarily manually actuates a start button 28 which is accessible on a control panel 29.  
  Upon this momentary actuation, the packaging machine 12, which is the subject of the present invention, automatically draws the tallied articles 24, which have been stacked at the loading zone, into the machine. It automatically wraps the articles and dispenses wrapped packages onto an exit package retaining station 30. The customer may then proceed to the retaining station 30 and withdraw the packages for carrying from the grocery store.  
  The packaging machine 12 is. for purposes of safety, cleanliness and appearance, mounted in a suitable cabinet which includes side panels 32 and 34 and top 36. However. in all the subsequent drawings the cabinet panels are removed and additionally in FIGS. 2-4 the support frame is not shown for clarity.  
  The entire packaging machine is mounted to a suitable support frame 38 preferably constructed from tubular steel of rectangular cross-section and welded to form butt joints at intersecting frame members.  
  As seen in FIG. I, the loading zone 26 is protectively surrounded by a horizontal. stationary platform 39. The platform 39 however. has an opening 41 which defines both lateral boundaries and the forward longitudinal boundary of the loading station 26. The frame and cabinet are formed so that there are no obstructions above or in front of the loading station 26 to facilitate the placement of articles at the loading station.  
  Referring now to FIG. 2, for a general description of the packaging machine mechanisms, the unobstructed loading station 26 is formed above the opening 41 in the platform 39 which is not visible in FIG. 2. An endless conveyor 44 is operatively mounted within the support frame. This conveyor 44 is formed with an endless series of loading zones such as loading zones 46a. 46b and 46c which are sequentially positionable in horizontal operable alignment beneath the loading station 26 by advancement of the conveyor 44. The conveyor 44 is drivingly advanceable in discrete loading zone incrc ments in a downstream direction 48 along the bottom of a treatment passageway which is formed in the support frame 38. This treatment passageway extends downstream from the loading station 26 for convey ance of the grocery articles during treatment. Down stream from the loading station 26 along the treatment passageway are in order a welding station 40, a heat shrink station 42, a cooling station 43 and finally an exit package retaining station 30.  
  Also mounted to the support frame 38 is a film feed means for feeding a first. heat shrinkable film ribbon 50 from a supply roll 52 horizontally and loosely onto the conveyer 44 in a feeding direction past the loading sta tion 26. The film feed means also feeds a second. heat shrinkable film ribbon 54 from a supply roll 56 down wardly and in unobstructive avoidance of the loading station 26 to the first film ribbon 50. These film ribbons 50 and 54 meet adjacent the downstream boundary of the loading station 26. The film feed means and in particular the rolls 52 and 56 are responsive and feed film whenever the film is anchored to the conveyor 44 by grocery store articles and is pulled by advancement of the conveyer.  
  A transverse welding and severing means indicated generally as 58 is mounted at the downstream side of the loading station 26 and at the upstream boundary of the welding station 40. Its function is to laterally bond the second film ribbon S4 to the first film ribbon 50 intermediate the particular loading zone of the conveyer which is positioned at the loading station 26 and the loading zone 46c of the conveyer which is positioned at the welding station 40 and for also severing the ribbon intermediate such a bond.  
  Further downstream along the article treating pas sageway is a heat shrink station 42 at which a heat shrink means 60 is mounted. Preferably, the heat shrink station 42 is immediately downstream of the welding station 40 and operates to heat and shrink film which is loosely wrapped around the articles and positioned at the shrink station 42.  
  Downstream of the shrink station 42 is a cooling station 43. It is simply a region protectively separated from customers by a portion ofthe cabinet but adjacent the exit to permit cooling of the heated package during an operating cycle prior to its exit onto the package retaining station 30.  
  Control means is provided for advancing the conveyer 44 an increment of one loading zone in response to a momentary manual actuation of the start button 28 illustrated in FIG. 1. The control means also controls the operation ofthe welding and severing means 58 and the operation of the heat shrink means 60 as subse quently described below.  
  The apparatus of the invention can now be described in more detail. For convenience, FIGS. 24 illustrate the entire packaging machine while FlGS. 5-7 are devoted primarily to the loading station and the welding station and FIGS. 8, 9 and 10 illustrate the heat shrink station and the retaining station 30.  
  The conveyer 44 comprises a pair of spaced, parallel, synchronously driven drive chains 70 and 72. A plural ity of steel rods, such as rod 71, laterally join these drive chains 70 and 72. The rods are mounted between opposite pivot pins of the links in the drive chains 70 and 72. Contiguous groupings of these rods form the loading zones such as loading zones 46:), 46b and 46c which are separated by intermediate gaps, such as gap 76, which are devoid of such lateral rods. These loading zones move along the treatment passageway and carry articles in serial sequence to the various treatment stations.  
  Each loading zone, such as the loading zone 46a is preferably bounded by a peripheral fence which comprises outwardly extending lateral rails and outwardly extending longitudinally aligned segmental shoulders which are spaced inwardly from the sides of the convcyer. in the preferred embodiment, the longitudinal, segmental shoulders are formed by the longitudinally aligned inner ends, such as the end 78, of a plurality of tubes, such as tube 80. These tubes are welded parallel to adjacent pairs of the lateral rods. As will be seen, the tubes not only confine the grocery articles to the loading zone but additionally provide conveyer support for the heat shrinkable wrapping film prior to the heat shrink process. Without them, the film would tend, prior to being shrunk, to overlap or hang over the lateral edges of the conveyer 44 and become caught in the working mechanisms or improperly shrunk.  
  The laterally aligned portions of the peripheral fence which surrounds each loading zone comprises lateral fence rods mounted outwardly of the conveyer and welded on the upper side of the longitudinally aligned tubes. For example, this structure may be seen most clearly with reference to FIGS. 2, 3 and 10. Loading zone 46a has its lateral end fence portions formed by lateral rods 84 and 86 which are welded to tubes 88a, 88b, 88c and 88d and extend laterally across the loading zone. Consequently, these lateral fence rods are alignable in near registration with the forward and rearward boundaries of the loading station 26 and the entire peripheral fence conveniently defines the region in which the attendant 14 positions the articles to be packaged.  
  The conveyer 44 is driven by a suitable drive motor 90 which is drivingly connected by a drive chain, V-belt or similar suitable means 92 to the sprocket wheel or pulley at the rearward end of the conveyor 44. This driving motor 90 is of course actuated by the control means as described below.  
  The film feed means is provided to feed ribbons of packaging film from a first supply roll 52 mounted beneath the conveyer 44 and from a second supply roll 56 mounted above the conveyer 44. The first supply roll 52 rests upon a pair of driven rolls 94 and 96 which are driven through a suitable drive chain 98 by an electric motor 100. Actuation of the motor I00 rotates the rolis 94 and 96 which in turn rotate the supply roll 52 for feeding film.  
  The second supply roll 56 rests upon a pair of similar rolls I02 and 104 which are motor driven through a suitable drive chain I06 by an electric motor 108. This motor when actuated similarly rotates the supply roll 56 for feeding film.  
  As seen most clearly in FIG. 3, a ribbon of film is fed from the first film supply roll 52 over the top of an idle roll 112, beneath a dancer roll 114, over the top of the second idel roll 116 and then loosely across the top of the conveyer beneath the loading zone 26 to at least the downstream side of the loading station 26. In a similar manner, a film ribbon 118 is fed from the second film supply roll 56 above an idle roll 120, beneath a second dancer roll 122, over further idle rolls I24 and 126 and downwardly in unobstructive avoidance of the loading station 26. This film ribbon 118 joins the film ribbon 110 from the lower supply roll 52 at the downstream edge side of the loading station 26.  
  Each of the dancer rolls 114 and 122 have their ends extending into oppositely facing U-shaped channels which are vertically aligned so that these dancer rolls are free to move reciprocatingly in a vertical path. Each dancer roll rests upon the switch arm of cooperating microswitches 128 and 130 which are actuated whenever their cooperating dancer roll is raised from its switch arm. Actuation of the switch 128 energizes the feed motor I00 to unwind the lower roll 52. Actuation of the microswitch 130 similarly actuates the motor 108 to feed film from the upper feed roll 56. Consequently, whenever the conveyer is advanced and pulls the film along the conveyer, the dancer rolls 114 and 122 are lifted from the microswitches thus energizing the feeding drive motors 108 and 100. Of course all the idle rolls and the driven rolls are suitably journalled in bearings mounted on the frame but which are not shown for purposes of clarity.  
  Briefly described, the welding and severing means comprises a pair of heating and bumper members one of which is movable relative to the other. They are mounted on the upstream side of the welding station in registration with the gap between adjacent loading zones. Upon energization by the control means, the movable member descends toward the fixed member through the gap and intermediately grips the overlapping film ribbons and heats them as they lie interposed between these members. Suitable welding and severing means for purposes of this invention have been shown in the prior art for example in U.S. Pat. Nos. 3,289,386; 3,653,l77 or 3,564,810.  
  Such welding and severing means may include linear heating elements, such as wires which are covered with a suitable Teflon protective cover. Upon being heated, they weld the film ribbons which are interposed between the pair of heating and bumper members. Severing may similarly be performed by mounting a third linear heating wire on one of the members and heating it at the appropriate time. Preferably, such a linear heater will be mechanically passed through the ribbons to sever them. All these heating elements or other welding and severing devices can be mounted in various alternative arrangements on either the movable member or the stationary member.  
  Microswitehes are used to detect, for the control means, when the cross beam 147 is at the upper and lower limits of its desired reciprocation. A weld down switch WDS is mounted on the vertical rack receiving tube 161 and is provided with an upwardly extending actuation rod 163. A horizontally protruding finger depresses the rod 163 to actuate the weld down switch WDS when the movable welding and severing beam 146 arrives at its proper descended position. Similarly, a weld up switch WUS is linked to an actuation rod 167 which slidably passes through a hole in a horizontally extending arm 169. A nut 171 is fixed to the rod 167 above the arm 169 so that the rod 167 is lifted to actuate the weld up switch WUS when the weld beam 146 rises to its proper uppermost position. Thus, when the cross beam 147 is at the top of its reciprocation, the weld up switch WUS is actuated and when it is at the lower limit of its reciprocation, the weld down switch WDS is similarly actuated. The heating elements utilized in the welding and severing means are suitably connected through lead wires not shown to the control means which is described below.  
  Referring now to FIGS. 24 and 810, the loading zone 46b is illustrated in FIG. 2 as centered in the shrink station 42. The shrink means 60 mounted at the shrink station 42 includes a pair of infrared radiation tubes 180 and 182 mounted at the shrink station below the upper loop of the conveyer. Mounted above the shrink station is a rectangular, horizontally aligned, shrink frame forming a carriage 184. A pair of infrared radiating tubes are mounted on each inner side wall of each side of the carriage 184. For example, the radiators 186 and 188 are mounted on the inner rear side 1911 of the carriage 184. A pair of vertical rack members 192 and 194 are fixedly mounted to laterally opposite sides 196 and 198 of the shrink carriage 184. These racks 192 and 194 extend downwardly on opposite sides of the article treating passageway and into driving engagement with motor driven pinions 200 and 202.  
  The pinions 200 and 202 are fixed to a drive shaft 204 which is driven by an electric motor 212 through sprockets 206 and 208 and cooperating drive chain 210.  
  As shown most clearly in FIG. 8, each of the vertical racks 192 and 194 are slidably engaged in a mating rectangular, tubular member such as tubular member 220 which has a cut out 222 to permit access of the pinion 200 to driving engagement with the vertical rack member 192. i  
  Switches are also used in association with the shrink frame carriage 184 for detecting the extreme upper and lower limits of the reciprocation of the shrink frame. A frame down switch FDS and a frame up switch FUS are mounted to the vertical tubular member 220. The frame up switch FUS is provided with a pivotal, spring biased cam follower type actuation arm 213 having ac cess to the smooth side of the rack 192 through a cut out 215 in the tubular member 220. When the lower end of the rack 192 is raised above the pivot arm 213 the arm 213 pivots to actuate the frame up switch FUS. Similarly, the frame down switch FDS has a pivot arm which is pivoted downwardly to actuate the switch FDS, when depressed by the bottom of rack 192. Thus, the frame up switch FUS is actuated when the frame 184 is at the top of its ascent and the frame down switch FDS is actuated when the frame is at the bottom of its descent.  
  The infrared radiators are connected by suitable lead wires (not shown) to the control means and by the control means to suitable power supplies. When energized by the control means, the lower infrared radiators 180 and 182 radiate heat energy upwardly through the conveyer between the rods connecting the opposite drive chains 70 and 72 thereof. Similarly, the carriage mounted infrared radiators radiate heat energy as the carriage descends and as it ascends around a package positioned at the shrink station. The heat causes the package to shrink in the known manner.  
  The control means may be provided with a dwell timer so that the shrink carriage 184 will dwell for a se lected time interval at the lower limit of its descent. We have found that this substantially enhances the quality of resultant package. Similarly, the control means desirably also employs a timing means for controlling the heating time and dwell at the bottom for the welding and severing means as described below.  
  We have found that a radiation responsive temperature detector 287 of the type using a photo-resistor or photo-diode for example, can advantageously be used to detect the temperature of the infrared radiating tubes used at the shrink station. For example, the control means may initiate energization of the infrared ra diating tubes at the beginning of the descent of the shrink frame 184.  
  However, the shrink frame 184 will be automatically held at the bottom of its descent at least until the infrared radiating tubes have attained a selected temperature such as, for example 1,800F. A timer may be used in conjunction with the temperature sensor to delay the bottom dwell a selected time after the infrared tubes reach the selected temperature.  
  Such operation in effect extends the bottom dwell time to permit warm up of cold infrared tubes but shortens the dwell when the infrared tubes are already in a partially heated condition when energized. Consequently, both continuous and intermittant operation are accommodated.  
  Additionally, we found it advantageous to include a photo-electric cell detecting means including a photodetector 230 and an associated light source 232. These are mounted at the weld station 40 to detect the presence or absence of articles on the loading zone 46(&#39; positioned in FIG. 2 at the welding station 40. This photoelectric detector 230 determines whether articles are present at the weld station so that the welding and severing means should be actuated and also determines whether shrink means 60 should be actuated after the conveyer 44 is advanced one loading zone increment. Its operation is further described below.  
  Finally, a series of small cams, which protrude outwardly, are connected to the conveyer drive chain 72. Each such cam, such as the cams 234 and 236, are associated with a single loading zone of the conveyer. Each cam is identically positioned relative to its associated loading zone and operates to actuate a cam follower switch 238 which is mounted to the support frame rearwardly of the shrink station 42. As described below, this cam follower operated switch 238 detects the positioning of the conveyerand cooperates as a part of the control means. It assures that the conveyer is advanced precisely in single loading zone increments in response to the actuation of the start button 28.  
  The exit storage area or package retaining station 30 receives the packaged articles. It is simply a plurality of freely rotatable, idle rolls which are aligned along a downwardly inclined path so that packages may slide by gravity to the rearward end of the packaging machine to await being carried from the grocery store.  
 MECHANICAL OPERATION The operation of the preferred embodiment illustrated in the drawings may be described with particular reference to FIGS. 3 and 4. The attendant places the individual grocery articles in the loading station 26 by positioning them on the film ribbon 110 which lays upon the conveyor at the loading zone 46d. When the attendant is satisfied that the loading station 26 is sufficiently filled with tallied grocery articles, she momentarily depresses the start button 28 illustrated in FIG. 1. The remainder of the mechanical operation is automatic and is controlled by the control means discussed below. The conveyor immediately advances one loading zone increment in a downstream direction 48. Re ferring to FIG. 3, the conveyer advances until the cam follower switch 238 has ridden over the cam 234 and is released by the cam 234. The conveyer halts upon such release.  
  The loading zone 46d is transferred to the welding station 40. Because the grocery articles anchor the film ribbons 110 and 118 to the conveyer, this conveyer movement pulls on the film ribbons 110 and 118. The initial pull lifts the dancer rolls 114 and 122 from their cooperating switches 128 and 130 thus energizing the film feed drive motors 110 and 108. Consequently, film is metered from the film feed rolls 52 and 56 until the conveyer ceases its advance and the dancer rolls 114 and 122 settle back down upon their switches 128 and 130 to deenergize their associated drive motors 100 and 108. In this manner, the grocery articles 24 are moved to the position 240 shown in FIG. 4 with the upper film ribbon 118 drawn over the top of the articles 240.  
  As soon as the conveyer stops advancing, a new loading zone is presented at the loading station 26 and the attendant may immediately begin to refill the loading station for the next package. There is no need to wait for subsequent operations to be completed.  
  Simultaneously, the control circuit senses, by means of the photo-electric detector 230, that a package is present at the welding station 40.  
  With the package 24a present at the welding station 40, the control means energizes motor 156 thereby rotating pinion 152 and lowering rack 148. This lowers the cross beam 147 and any associated heating elements. As the cross beam 147 begins its descent, the weld up switch WUS is initially released. The cross beam 147 continues to descend until it extends through the gap between the loading zones at the loading station and at the weld station and finally the weld down switch WDS is operated. The weld down switch is positioned so that it is operated when the heating elements are properly positioned with the film ribbons intermediately gripped between the movable welding and severing member and the stationary welding and severing member 313.  
  The control circuit, upon actuation of the weld down switch WDS deenergizes the motor 156. It also energizes the heating elements and timers which control the length of time that the motor 156 is deenergized and that the welding and severing heating elements are energized. After a selected time delay, these heating elements are deenergized and after a further delay, the motor 156 is again energized but in a reverse direction so that it begins raising the rack members 148 and 150. The rack members continue to be raised until the weld up switch WUS is actuated which causes the control means to again deenergize the weld bar driving motor 156.  
  The heating means in the weld beam 147 heats the thermoplastic film ribbons and bonds them together. Simultaneously, the film ribbon around articles 240 is severed from feed ribbons and 118 intermediate the welded bond. The film on the packaged articles 240, however, limply lays upon them at this stage.  
  When the attendant initially depressed the start button 28 the photoelectric detector determined that no package was present at the weld station 40. The control means therefore inhibited the operation of the shrink means 60 during the succeeding cycle of operation. Consequently, if the package 240 is the first package fed into the packaging machine then the machine will cease operating after the weld and sever operation until the attendant again depresses the start button 28.  
  When the attendant has refilled the loading station 26, she again depresses the start button 28. The photoelectric detector 230 immediately detects the package 24a on its way to the shrink station 42. The cycle proceeds at the weld station 40 identically as described above. The conveyer is again initially advanced one loading zone increment and then stopped. The weld operation then proceeds. Simultaneously, the shrink means 60 will now begin operation immediately after the conveyer stops. The shrink frame drive motor 212 is energized to rotate the pinion 200 and lower the shrink frame 184. The frame up switch FUS is immediately released and the shrink frame 184 continues to descend until the frame switch is actuated by the rack 192.  
  All of the infrared radiating tubes, such as the lower tubes and 182 and the tubes in the shrink frame, for example tubes 186 and 188, may be energized according to a desired, empirically proven, timing cycle. For example, they may be energized immediately upon the beginning of the descent of the shrink frame 184 and may continue until the frame has returned to its raised position As the shrink frame 184 begins to descend, it surrounds the package, now positioned at 24b, and heats the thermoplastic heat shrinkable film causing it to shrink tightly around the grocery articles. Simultaneously, the lower infrared tubes 180 and 182 radiate heat upwardly at the package for the same purpose.  
  When the shrink frame 184 reaches the bottom of its descent and actuates the frame down switch PBS, the control means deenergized the drive motor 212 and actuates a timing means which determines the time interval the shrink frame will remain in its lower position. Alternatively, the package temperature or preferably the tube temperature is sensed by a radiation responsive detector. After the desired time interval or after a suitable temperature is reached or both, the drive motor 212 is again energized but in a reverse direction. This reversely rotates the pinion 200 lifting the racks 192 and 194 to lift the shrink frame 184 to its raised position. When the shrink frame 184 reaches the top of its path, the frame up switch FUS is actuated to again deenergize the drive motor 212.  
  We have experimentally found it advantageous to construct the control means so that the infrared radiating tubes are deenergized shortly after the shrink frame begins to ascend. As explained below a timer operates to accomplish this a selected time after ascent is begun.  
  This operation not only eliminates the burning of holes in the top of the package but additionally prevents excessive consumption of electrical power and generation of unwanted heat.  
  These are some of the primary advantages of the shrink structure described above over the conventional heat shrink tunnel. The conventional tunnel is constantly maintained at a suitable shrink temperature, This may be acceptable for a continuous, uninterrupted industrial application. However, its continuous heat generation and power consumption are unacceptable for an intermittent retail sales operation.  
  When the attendant again refills the loading station 26 she will again depress the starting button 28 and the cycle will be repeated with each package moving one loading zone increment in the downstream direction 48. The packages are ultimately delivered onto the exit storage table or retaining station 30 and slide down the rollers to the end bumper where they are retained until the customer withdraws them and carries them from the store.  
  It can be seen from the above that one advantage of this packaging machine is that the loading, wrapping and shrinking operations occur serially in three sepa rate operations. All operations may be simultaneously performed on different packages. Consequently, the maximum cycle time necessary is only the cycle time needed for the longest of these three operations. It is not necessary that each cycle be long enough for all three operations to be done to a single package. The result is a greatly increased rate at which grocery store articles can be packaged and consequently at which customers can be serviced.  
  When the last package in a sequence has been loaded into the loading station 26, the attendant continues to depress the start button 28 after each operation is completed. However, because the film ribbon 110 is laying loosely upon the conveyer 44 at the loading station 26, film will not be drawn into the packaging machine when no packages are present at the loading station 26. The conveyer will merely slip beneath the film ribbon H0.  
  The welding operation at the weld station 40 and the heat shrinking operation at the heat shrink station 42 will occur only when packages are present at their stations which require their treatment. The photo-electric detector circuit consequently eliminates unnecessary operation of the packaging machine. Thus, the attendant either continues depressing the start button until all the packages for one customer are delivered to the exit retaining station 30 or immediately continues the operation by servicing the next customer.  
 CONTROL MEANS CIRCUIT The circuit diagram for the control means which controls the operation of the above packaging machine is illustrated in FIGS. 11 and 12. The logic, timing, and detecting circuitry is illustrated in FIG. 11 while the motor operating and heating circuitry is illustrated in FIG. 12. These circuits are, however, joined along four leads at W, X, Y and Z.  
  The abbreviations used in the circuit diagram to indicate the various relays and their associated contacts are defined in the following table.  
  Many of the relays and switches have multiple sets of contacts all of which have associated therewith the appropriate abbreviations. All contacts have identical abbreviations associated with them are operated by and work simultaneously with the relay coil having the identical associated abbreviations.  
 ABBREVIATIONS USED ON SCHEMATIC PE Photoelectric sensor HWF hot wire fuse (cutting wire) IWE (WF) impulse weld fuse CLI Cycle light impedance (green lens) SLI Stop light impedance (red lens) CSL Cycle switch light (Green) SSL Stop switch light (red) PEL Photo-electric light (source) LFM Lower film motor SFM Shrink frame motor CM Conveyer motor UFM Upper film motor WM weld motor BTR bottom timer relay (shrink frame) DTR dwell timer relay (movable weld member) ECR end cycle relay EWR end weld relay FCR frame control relay (shrink frame) FDE frame down relay (shrink frame) FUR frame up relay (shrink frame) HTR heater timer relay LCR lamp control relay (powers infrared radiator tubes) MCR master cycle relay PER photo-electric relay SCR seal cycle relay (slants weld and/or shrink) CIR conveyer in relay (operates conveyer) CSR conveyer stop relay (stops conveyer) WCR weld control relay (powers weld member) WDR weld down relay WTR weld timer relay WUR weld up relay FDS frame down switch FUS frame up switch WDS weld down switch WUS weld up switch HWS hot wire switch (T selector) The switches indicating whether the weld beam and the shrink frame are in their up or down positions, have their appropriate position marked up or down to indicate the switch position when its associated part is in the up or down position. The unmarked side of each of these double throw switches represents that the condition is not up or not down. Thus, for all states except the indicated states, these switches are in their unmarked positions.  
  Referring now to FIGS. 11 and 12, power is applied to the control means circuit at its inputs 300 and 302. It is suitably fused by a fuse 301 and switched by a main power switch 306 which preferably is accessible to the attendant 14 at the control panel 29 at the front of the packaging machine 12 in FIG. 1. When the attendant momentarily depresses the start button switch 28 to actuate its contacts 280, a master cycle relay 308 is energized through the weld up switch 310, the frame up switch 312 and the emergency stop switch 322 which is mechanically biased to a closed state.  
  This momentary energization of the master cycle relay 308 closes its contacts 314 so that is is latched closed by current supplied by through contacts 314 and contacts 316 and 318 of the energized dwell timing relay 374 and the end cycle relay 460. Simultaneously, a stop switch light 320, which is mounted behind and illuminates the emergency stop switch 322 accessible on the control panel 29, is illuminated. The light 320 has a current limiting resistance 324. The light 320 indicates that the machine is cycling and also draws the attendants attention to the stop button 322 if an emergency situation would arise. As can be seen in FIG. 11, depression of the emergency stop switch 322 immediately deenergizes the master cycle relay 308 bringing all operations to an immediate halt.  
  Actuation of the master cycle relay 308 also simultaneously closes the contacts 326 of the master cycle relay which apply power through the still closed contacts 328 of the seal control relay 344 and through the weld up switch 330 to the conveyer in relay 332.  
  The application of power to the conveyer in relay 332 closes contacts 334 (illustrated in FIG. 12) of the conveyer in relay 332. These contacts apply power to the conveyer motor 90 which as shown in FIG. 12 is provided with an internal brake 336. This internal brake 336 as well as the internal brakes on the other motors serves to immediately stop the motor as soon as the motor is deenergized. This prevents the systems inertia from carrying the driven mechanisms past their intended path terminus.  
  Eventually, a cam on the conveyer 44, such as the earn 234 illustrated in FIG. 3, raises the cam follower at the cam follower switch 238 so that in FIG. 11, the single-pole double throw cam follower switch 238 is switched to its cam up position. This in turn applies power to a conveyer stop relay 340. Actuation of the conveyer stop relay 340 closes its contacts 342 which latch it in an energized condition and simultaneously close its contacts 343. However, the conveyer continues operating because power is still applied to the conveyer in relay 332.  
  However, as soon as the cam follower switch 238 is passed by the cam 234, its cam follower falls, switching the cam follower switch 238 to its cam down position. This immediately energizes the seal cycle relay 344 which in turn opens the seal cycle relay contacts 328 to deenergize the conveyer in relay 332. The conveyer 44 is thereby stopped from further forward movement after it has been advanced a single loading zone incremerit.  
  Articles initially positioned at the loading station an chor the film to the conveyer so that the conveyer movement pulls film from the film supply rolls 52 and 56 as described above. The upper feed motor I08 and the lower feed motor 100 and both equipped with internal brakes 339 and 34] which prevent overfeed and excessive loose film.  
  The welding and severing means and the heat shrink means will now begin simultaneous operation if appro priate. Their operation is appropriate when articles are present at their station to be treated. They may best be described individually each without reference to the other with the understanding that both operations may be occurring simultaneously.  
  As previously described, the packaging machine is provided at the welding station 40 with a continuous illuminated light source 232 which is directed at a photoelectric detector 230. The photoelectric detector 230 is a conventional item which may be purchased. For purposes of the present application it is sufficient to in dicate that its output 346 is effectively connected to the potential of the input power terminal 300 when light from the light source 232 is blocked from striking the photoelectric detector 230. When light from the light source 230 is incident upon the photo-electric detector 230, the detectors output 346 is at substantially the potential of the power input terminal 302. The output 346 of the photo-electric detector is connected to operate a photo-electric relay 348 Therefore it can be seen that when the cam follower switch 238 closes, it energizes the seal cycle relay 344. This causes the seal cycle relay contacts 350 to close. if articles are present at the weld station 40, the photoelectric relay 348 will be energized to close photoelectric relay contacts 352. In this manner, power may now be applied to a weld down relay 354 through contacts 326 of the master control relay 308, terminals 350 of the seal cycle relay 344, terminals 356 of the master cycle relay 308, terminals 352 of the photoelectric relay 348 and through the closed terminals 360 and 36 of the end weld relay 362 and the weld up relay 364.  
  Energization of the weld down relay 354 in this manner closes the contacts 368 and 370 in FIG. 12 to apply power to the weld drive motor 156 driving it in a direction which lowers the movable weld member 147.  
  The motor 156 continues driving the weld bar in a downward direction until the weld down switch 372 switches to its down position. S uch movement of the weld down switch 372 immediately deenergizes the weld down relay 354 cutting power from the weld motor 156. Its internal brake 337 then immediately stops further travel. Simultaneously, this movement of the weld down switch 372 applies power to the dwell timer relay 374 and the weld timer relay 376.  
  The operation of the dwell timer relay 374 and the weld timer relay 376 and in fact the operation of all the timer relays in the present circuit is conventional. A selected time interval after the timing relay is energized, contacts are actuated. Thus, a timer relay is initially energized but does nothing. After a selected time interval, it changes states and remains in the changed state until power is removed from its input.  
  Therefore, movement of the weld down switch 372 to its down position not only initiates the operation of the dwell timer relay 374 and the weld timer relay 376 but simultaneously applies power to the weld control relay 380 in FIG. 12 through normally closed contacts 382 of the weld timer relay 376. Energization of the weld control relay 380 of FIG. 12 causes immediate closure of its contacts 384 and 386 to apply power from the transformer 388 to the heating members 390 of the welding and severing means.  
  A first time interval after initial actuation of the weld time relay 376, it is switched to open its contacts 382 thereby deenergizing weld control relay 380 and in turn opening contacts 384 and 386 to quench the heating of the heating members 390.  
  The dwell timer relay 374 is set to a longer time interval to permit the welded and severed film to cool adequately. Subsequently. however, the dwell timer relay 374 also is actuated by its internal timing mechanism closing its contacts 392 and its contacts 394.  
  Closure of contacts 394 applies power to the weld up relay 364 through contacts 365 of the weld down relay 354 and the weld up switch 330. When the weld up relay 364 is operated. its contacts 400 and 402 are closed thereby applying power to the weld motor 156 in an opposite direction to drive the weld bar l47 upwardly. When the weld bar 147 reaches the top of its