US3712020A - System and method of wrapping - Google Patents

Abstract

The invention is directed to a system whereby a product is sealed in a fusible plastic wrapper by shriveling and fusing portions of the latter.

Description

United States Patent Norr et a1. I Jan. 23, 1973 1 SYSTEM AND METHOD OF WRAPPING 3,115,735 12/1963 Harrison ..5'3/184 W l.. 3 1751 Dav-d Fort Wayne; Men 3.53 3?; 311321 652 522337.? 53 c-Nm'iGrabllLboth oflfld- 3,222,844 12/1965 Smithetal... .....53/209x 7 A z 3,380,734 4/1968 Laumer ..27l/76 3] ssgnee 2" F hd'hnufactumg 3,383,832 5/1968 Grant et al... .....53/209 ayne 3,418,785 12/1968 Duryee ..53/184 22 Filed; Feb. 6, 19 9 3,501,892 3/1970 Pikal ..53/180 [21 1 Appl. No.: 797,134 Primary Examiner-Gerald M. Forlenza Assistant Examiner-Frank E. Werner 52 us. c1. ..s3/30, 53/25, 53/33, Ammey-chafless' Pem'd 53/127, 53/184, 53/209 511 1m.c1. ..B65b 11/52 [57] ABSTRACT Field of Search....53/30,3 The invention is directed to a system whereby a /25 product is sealed in a fusible plastic wrapper by shriveling and fusing portions of the latter. [56] References Cited 39 Claims, 41 Drawing Figures UNITED STATES PATENTS 3,097,464 7/1963 Reeves ..53/209 FRCWRAP SEALER 500] C DITIONER WRAPPER EED DISPENSER CONTROL 'T PATENTEDmza 197s 3.712.020 311m cam 13 INVENTOILS DAv/DA. [VG/PR 27 H BYROBERT C.NORR

0 WRAPPER FEED S60 10 M0102 ATTORNEY PATENIEDJAH23 192s 3.712.020 SHEET on HF 13 -\-0e H 21% viutjp i To M -m INVENTORS' DA V/D ANORR BY RoaERT C-NORR @4 4 Z ATTQ NEY SHEET OSUF 13 ESI c M 5 Z P I, 0 7 u s 2 Z, a 2 I 2 MN 1 5 Q a m 3 2 //z 2 I 9, mm m aa 1 m w a \m s OH MHZ f Hill 20 7 INVENTORS DA V/D ,4. NORR BY ROBERT c. N

1/6 ,JjWATTOR/VEY PAIENTEDJANZS I975 3,712,020

SHEET 09 [1F 13 ssl 4 DAVIDA-NORIE BY ROBERT C.NORR

J 3 3 INVENTORS- I PATENTEDJAH 23 I915 SHEET lUUF 13 @m I. R woo M VAC mT V Am DB 0 R Y B ATTORNEY PAIENIEDJI'IH23 I973 3,712,020

SHEET 11 [1F 13 i'yfja SEALING CHA SPEED CONTROL [IE I] OR MOTOR so; I 632 I coa 63s I G36 M636 mvzivmlas- '36 I AV/0 A. Norm i m- ROBERT cNoRR (law mg, A T TOR N EV SYSTEM AND METHOD OF WRAPPING The invention, among other things, relates generally to wrapping products, such as frost coated sliced meat products, in plastic wrappers, and more particularly, is directed to a system or apparatus which preferably includes an elongated conveyor, wrapper feed assembly for feeding wrappers onto the conveyor, a dispenser for feeding the products to a conditioner which removes the frost and selectively places the products upon the wrappers, an assembly or means for effecting a partial wrapping or prewrap of the products while the products are transported by the conveyor, and a sealer through which the partially wrapped products travel for the purpose of changing the structural characteristics of the wrapper by shriveling and shrinking portions thereof whereby to provide a rib for sealing each product in a wrapper and which may be easily ripped or pulled away to facilitate removal of the wrapper when the product is ready for use.

One of the significant objects of the invention is to provide a wrapper feed assembly which is preferably operable in conjunction with the elongated conveyor above referred to for feeding a roll of plastic material thereto in such a manner that a free end portion thereof will be continuously directed onto a slightly inclined suspended area of the conveyor and an electrically heated movable cutter device will successively engage the material which on such area as it unwinds for the purpose of severing or cutting the material into wrappers for deposit at predetermined longitudinally spaced positions on the conveyor.

Another object of the invention is to provide the wrapper feed assembly with a plurality of controls for synchronizing the operation of this assembly with that of the conditioner and dispenser of the system.

A further object of the invention is to provide a system in which the prewrap assembly thereof is associated with the conveyor and wrapper feed assembly in a manner whereby after the product is freed of frost by the conditioner the latter will deposit each product substantially centrally on substantially one-half portion of each wrapper so that a blast or current of air from the prewrap assembly will direct the other half portion of the wrapper against and over a former onto an upper moistened surface of each product for adherance thereto. The size of the wrappers are preferably predetermined so that the halves or opposed portions thereof will extend or project laterally from edge portions of the product in order to provide sufficient excess material which may be shrunk and shriveled when the wrapped products are subjected to heat in an oven or chamber constituting a component of the sealer above referred to.

Another object of the invention is to provide a dispenser which will readily accommodate one or a plurality of rows of products of variable sizes without prior manual adjustment of any of its components and wherein provision is made for maintaining the products in each row in a tilted back stacked relation while the products are fed or pushed off inclined ways to a high point or location thereon where they selectively slide backwardly down an apron and discharge to the conditioner, or if so desired, directly onto the wrappers in the event that the conditioner is not utilized as a component of the system.

A specific object of the invention is to provide a dispenser of the character above referred to which also preferably includes a pair of parallel conveyors having movers or pushers for successively automatically moving the rows of products up the ways and whereby, if so desired, one conveyor may be manually loaded or supplied with any desired number of products while the other conveyor is conveying its load to the conditioner and whereby each mover may be manually retracted to accommodate a load.

A particularly significant object of the invention is to provide a conditioner assembly which serves to condition frozen products such as frost coated slices of meat by removing the frost and cleansing the product by applying a film or thin layer of liquid to the surface of the products so that when the products are refrozen in a wrapper, the film of moisture will act to bond the wrapper to the product to obtain a frost-free package whereby the material or true characteristics of the product will be clearly presented to customers for purchase. The film or layer of liquid is preferably sprayed onto the upper face and edges of each product as it is conveyed up an inclined surface for eventual deposit onto a wrapper previously fed to and located on the conveyor by by the wrapper feed assembly and cutter device.

Another object of the invention is to provide a conditioner of the character above described in which an upper wall of a sump constitutes the inclined surface and any surplus liquid sprayed onto the product will lubricate the inclined surface to promote travel of the product thereon and apply a film of liquid to a bottom face or surface of the product and then drain off into the sump.

Another object is to provide components or assemblies which may be utilized as components of the apparatus or system as disclosed herein, as separate or individual units, or in combination with equipment not shown.

A further object of the invention is to provide a system which includes a sealer assembly which preferably comprises a lower structure provided with a chamber or oven and a conveyor belt and an upper superstructure having an upper relatively heavy conveyor belt which is supported so that a lower length or portion thereof will always loosely overhang and cooperate with the lower belt for jointly receiving and carrying the products therebetween. More specifically, the upper belt, although somewhat heavy, has sufficient resiliently flexible characteristics that it will, to some degree, conformingly engage the products and therefore, in conjunction with the weight factor, assist in stabilizing their travel between the belts. The organization is also preferably such that when the belts, constituting conveyor means, are not conveying products, they will normally engage one another over a relatively large area substantially corresponding to the width and length of the lower length of the upper belt which engages the lower belt.

Also, an object of the invention is to provide a sealer assembly of the character above described which includes a unique organization and method whereby hot air is preferably circulated in diagonal directions or in predetermined paths or patterns between the belts and against the partially wrapped or prewrapped products whereby the free edges of the wrappers will be caused to progressively shrivel and shrink about the product to completely seal the products therein and provide the rippable or tearable rib above referred to.

Another object of the invention is to provide a sealer in which the upper belt embodies improved principles of design and construction, including means for continuously cooling substantially an upper half or length of this belt prior to its engagement with the products and/or lower belt so as not to materially change the structural characteristics of the product, and means for synchronizing the movement of the belts.

A specific objective of the invention is to provide a wrapper lift which is preferably located in a space between an output end of the elongated conveyor and one of the conveyors of the sealer assembly whereby an upward current of air serves to lift and prevent a wrapper from falling into such space or gap and thereby promote uniform travel or transfer each partially wrapped product from one conveyor to the other without displacing the wrappers.

The apparatus or system offers other advantages with respect to efficiency, continuity in the operation of the various components thereof, capacity of output, durability and uniformity in the resultant product.

Additional objects and advantages of the invention or inventions above referred to will become apparent after the description hereinafter set forth is considered in conjunction with the drawings annexed hereto.

IN THE DRAWINGS FIG. 1 is a side elevational view of the apparatus or system;

FIG. 2 is an enlarged partial perspective view showing the operative relationship between a dispenser, conditioner, and a prewrap assembly of the system;

FIGS. 3 through 7 are directed to the dispenser and FIG. 3 is a top plan view thereof looking in the direction of the arrows 3-3 of FIG. 4;

FIG. 4 is a side elevational view taken substantially on line 4-4 of FIG. 3, with portions broken away for 'purposes of illustrating certain structure;

FIG. 10 is a top plan view of the conditioner, with portions in section for the purpose of illustrating details of construction;

FIG. 11 is a longitudinal vertical section taken substantially on line 11-] l of FIG. 10;

FIG. 12 is a transverse vertical section taken substantially on line 12-12 of FIG. 11;

FIG. 13 is a side view of one of the spray nozzles utilized in the conditioner;

FIGS. 14 through 22 are directed to a wrapper feed assembly and cutter device and FIG. 14 is a top plan view thereof;

FIG. 15 is a side elevational view of the structure shown in FIG. 14;

FIG. 16 is an enlarged partial side elevational view of a portion of the wrapper feed assembly shown in FIGS. 14 and 15;

FIG. 17 is an enlarged perspective view of a portion of the wrapper feed assembly showing the operative relationship of certain of the movable components thereof;

FIG. 18 is a partial vertical longitudinal view taken through the structure shown in FIG. 16 for the purpose of showing details of the structure;

FIG. 19 is an enlarged transverse section taken through the cutter device showing details of its construction;

FIG. 20 is an enlarged perspective view which shows, among other things, the operative relationship and purpose of certain controls of the system or apparatus;

FIG. 21 is an enlarged partial perspective view of a portion of the cutter device;

FIG. 22 is an enlarged partial perspective view, with portions in section, of one of the rollers utilized in conjunction with the wrapper feed;

FIG. 23 is a layout of the prewrap assembly which is utilized in conjunction with the conditioner and wrapper feed;

FIGS. 24, 25, 26, 27, 27a, 27b, 28, 29, and 30 are directed to the sealer assembly or structure and FIG. 24 is a side elevational view thereof;

FIG. 25 is an end elevational view of the assembly shown in FIG. 24;

FIG. 26 is a perspective view showing a speed reducer operatively associated with the structure for synchronizing the movement of conveyor belts constituting components of the assembly;

FIG. 27 is a horizontal section taken substantially on line 2727 of FIG. 28;

FIG. 27a is an enlarged transverse section taken through the upper belt of the assembly;

FIG. 27b is an enlarged transverse section through the lower belt of the assembly;

FIG. 28 is a vertical section taken through the assembly shown in FIG. 24;

FIG. 29 is a horizontal section taken substantially on line 29-29 of FIG. 28;

FIG. 30 is a transverse section taken substantially on line 30-30 of FIG. 28;

FIG. 31 is a perspective view showing one of the products prewrapped or partially wrapped for travel through the sealer;

FIG. 32 is a perspective view of the product showing its resultant sealed state or condition after having passed through the sealer;

FIG. 33 is an enlarged transverse section taken substantially on line 33-33 of FIG. 32 showing the shriveled or shrunk laterally extending portions of the wrapper which form the sealing rib or joint about the major portion of the resultant product;

FIG. 34 is a perspective showing whereby the seal may be ripped or torn away to facilitate access to the wrapped product when ready for use;

FIG. 36a is a modified electrical input side of the electrical system; and

FIGS. 35 through 38 are directed to the electrical circuitry.

The system or apparatus, may be modified in various respects as will be explained more in detail subsequently but as exemplified in FIG. 1, the system preferably includes: a dispenser generally designated 1 for selectively conveying products such as frost coated meat to a conditioner 300 which serves to remove the frost from the product and convey the defrosted products for deposit onto wrappers of fusible sheet material previously deposited on the elongated conveyor by a wrapper feed assembly 200; a prewrap assembly 400 which serves to fold or move a portion of the wrapper against or about the product to partially wrap the same; a sealer assembly 500 which receives the partially wrapped product and serves to fuse portions of each wrapper to seal a product therein; and a cabinet 600 provided with suitable controls for controlling the operation of the various components or assemblies of the system which will now be described hereinafter. It should be noted that the dispenser is provided with conveyor means for transporting the frost coated products to the conditioner; that the conditioner is provided with conveyor means for transporting the defrosted products to the elongated conveyor; that the sealer is provided with conveyor means; and that the elongated conveyor transfers the partially wrapped products to the conveyor means of the conditioner for conduction through the heat chamber thereof.

DISPENSER l The dispenser may be designed and constructed in various ways and as illustrated in FIGS. 1 through 7, serves to successively feed a pair of rows or stacks of products P to the conditioner assembly 300, above referred to, or if desired, the conditioner assembly may be omitted, in which event the product may be fed directly to the prewrap assembly 400 as exemplified in FIG. 8.

It should be observed that the dispenser as shown is disposed transversely with respect to the conditioner and that if utilized as in FIG. 8, it would extend transversely of the prewrap 400. The dispenser may be used independently of or in conjunction with the system or apparatus shown or with equipment not disclosed.

Referring more particularly to FIGS. 3 through 7, the dispenser, designated 1, comprises a rectangular boxlike frame 2 which is supported in an inclined position by a pair of short legs 3 and a pair of long legs 4 (only one of each of the legs are shown). The pairs of legs 3 and 4 are joined by side braces 5 and by end braces not shown. The frame 2 may be designed and constructed in various ways, but as illustrated, it is preferably open at the bottom and includes a pair of parallel side walls 6 and 7 and a pair of end walls 8 and 9.

The side walls 6 and 7 are respectively provided with upper inturned continuations providing planar ways or tracks 10 and 11 and with lower inturned flanges 12. The end walls 8 and 9 are provided with inturned upper and lower flanges 13 which engage the inner surfaces of the lower flanges 12 and the ways 10 and 11. The side walls 6 and 7 and end walls 8 and 9 may be secured together by any mode desired such as by screws or bolts 14.

The frame also includes a rectangular planar plate providing a center way 15 or track which is common to and located between the ways 10 and 11. More specifically in this respect, the ways l0, l1, and 15 are located in the same plane and the center way 15 is larger than the ways 10 and 11 and is spaced therefrom by a pair of longitudinal openings or slots 16 and 17.

A pair of transverse shafts l8 and 19 are rotatably mounted on the side walls 6 and 7 of the frame. A first pair of aligned sprockets 20 and 21 and a second pair of aligned sprockets 22 and 23 are respectively carried by the shafts l8 and 19. A belt in the form ofa chain 24 is carried by sprockets 20 and 21 and a belt in the form of a chain 25 is carried by the sprockets 22 and 23. A sprocket 26 is also carried by the shaft 19 and a belt 27 connects the sprockets 26 with a sprocket 28 carried by a speed reducer associated with an electric motor 29 provided with a switch S29. This motor is mounted on a platform 30 carried by a pair of the upper braces 5 as shown in FIG. 4.

An elongated bar or rail 31 is supported by suitable end fittings 32 carried by the end walls 8 and 9 of the frame 2 for supporting the bar directly below and in spaced relation to the longitudinal opening or slot 17. A second bar 33 corresponding to the bar 31 is similarly supported below the opening or slot 16. The bars 31 and 33 are preferably square in cross-section and slides 34 and 35 are respectively mounted thereon.

The slides may be designed and constructed in various ways but as shown in FIGS. 6' and 7, each preferably comprises four planar bearing members 36, 37, 38, and 39 of Nylon which are secured together in a square tube 40 by four screws 40' to provide a square formation which smoothly slidably receives one of the bars without the necessity of lubrication. The bearing members may be constructed of material other than Nylon. Each of the slides is provided with an abutment preferably in the form of a hook 41 which is adapted to periodically engage or receive an abutment in the form of a cross-pin 42 carried by a chain. The hook may be constructed of a pair of angled members which are preferably secured in abutting relation by screws or equivalent means and the cross-pin is secured to upstanding portions of a pair of special side links of a chain.

The slide 34 on the bar 31 is preferably provided with an upstanding L-shaped bracket 43 which extends through the slot 17 and is provided with a planar plate constituting a mover or pusher 44. The other slide 35 on the bar 33 is similarly provided with a bracket 45 and a mover 46. It. should be observed that the mover 44 and chain 24 constitute one conveyor; that the mover 46 and chain 25 constitute another conveyor; and that the movers or pushers are disposed at oblique angles of preferably 10 with reference to the plane formed by the ways 10, II, and 15 as shown in FIGS. 4

and 6 so that, for example, a plurality of products P of fairly generally uniform cross-dimensions or sizes may be stacked to lean back or tilt to the right against the mover or plate 46 and with their lower edges or portions engaging the ways so that such edges or portions will be the first to leave the ways as the products slide off high points of the ways. The mover or pusher plate 44 overlies the ways 11 and 15 and the mover or plate 46 overlies the ways 10 and 15. The side walls 6 and 7 of the frame 2 are preferably provided with upwardly extending elongated continuations 47 which assist in preventing accidental lateral discharge of the stacked products while they are being conveyed upwardly and forwardly on the ways.

The upper left extremity of the frame is preferably provided with a downturned inclined apron 48 which is connected to the end wall 8 of the frame for the purpose of successively delivering the products to the conditioner 300. The apron is of a width substantially corresponding to the width of the frame and is provided with a pair of independently operable switches S49 and S50, each having an inclined actuator 51 which extends upwardly through an opening provided therefor in the apron so that, for example, each of the products P in the row shown in FIG. 3, on reaching the high point on the ways 10 and 15, will fall back and slide down the apron to cause the lower edge of the product to engage the actuator to operate the switch S49 and then slide flatwise therebeyond and through a side opening 307 in the conditioner. The switches S49 and S50 are connected to the switch S29 of the motor 29 and to a control box generally designated 53 which will be later described.

The switches S49 and S50 are connected in parallel and in series with the instrumentalities in the control box 53 and constitute components of the electrical circuitry exemplified in FIGS. 35 through 38. The electrical circuitry is such that any desired number of products preferably within a range of sizes may be stacked against either or both of the movers or pushers 44 and 46 so that, for example, after one row has been completely dispensed, the other row will automatically take over and continue to direct products to the conditioner. The movers are manually selectively retractible and products may be manually placed or loaded into the dispenser against either one of the movers while the other is conveying.

The dispenser is preferably provided with a brake device, generally designated 52, for the purpose of preventing over-run of either of the conveyors. More specifically, the brake device serves to control the operation of the shaft 19 which is driven by the motor 29. This device is primarily supported on the end wall 9 of the frame 2 and among other things, includes the control box 53 above referred to which contains relays (shown in the electrical circuitry), a stationary arm 54 which carries a fixed electrically operable magnetic component 55 and a movable magnetic component 56 which is keyed to the shaft 19 and which when energized serves to forcibly engage the stationary component 55 and prevent rotation of the shaft and when de-energized permits free rotation of the shaft. As illustrated in FIGS. 4 and 5, a pair of conductors 57 connect the control box 53 with a switch S296, the latter of which forms part of a control system of the wrapper feed assembly 200 as shown in FIG. 20. The box isalsq connected to the motor 29 by a pair of conductors'58 and to a footswitch S60 by a pair of conductors 59. The. organization is preferably such that manual closingof the switch S29 will operate the motor 29 to cause simultaneous rotation of the shafts l8 and 19 to impart motion to the conveyor chains 24 and 25, which selectively operate the movers or pushers 44 and 46. When the actuator 51 of the switch S49 is depressed by a product to close this switch, the motor 29 is stopped and the brake 52 is operated to also prevent rotation of the shaft 19. During these non-operative periods of the motor and shaft 19, the foremost product in a row previously fed to the conditioner will be transported or conveyed therefrom onto one of a plurality of wrappers- 252 being moved forwardly on the elongated conveyor which is designated as component 212 of the wrapper feed assembly 200. The switch S296 of the wrapper feed control system is connected to the control box 53 and when opened serves to restart the motor 29 and deactivate the electric brake 52. The footswitch S actually serves as an emergency switch which when closed immediately stops the operation of the dispenser. The organization is preferably such that the switches S49 and S50 serve to respectively independently control the step-by-step movement of the movers of the dispenser. This operative relationship between the dispenser and the control system of the wrapper feed 200 is preferably such that the control system serves to place the dispenser either in an operative condition whereby actuation of the switches S49 and S50 will operate the movers or in an inoperative condition. The motor 29 may be turned on or off by a switch S29 on the control unit 600, by a switch S2 on a panel 430 of the control assembly of the wrapper feed or by plugging the extension cord shown in FIG. 4 directly into an electrical source, all of which will be described more in detail subsequently in connection with the electrical circuitry.

WRAPPER FEED 200 The wrapper feed assembly 200 may be utilized as a component of the system as shown in FIG. 1 or, if desired, as an independent unit, or in conjunction with other equipment not shown.

More particularly, certain of the wrapper feed structure, as depicted in FIGS. 14 through 22, is common to the prewrap assembly 400. The wrapper feed includes an elongated rectangular inverted channel 201 supported horizontally by a frame including two pairs of legs 202 and 203. The channel has a top planar wall or platen 204 and a pair of parallel side walls 205 having lower inturne d flanges. The left ends of the side walls 205 preferably support adjustable side plates or members 205 which in turn rotatably carry an idler roller 206. Extensions 207 are preferably detachably secured to the right ends of the side walls by bolts 208 and support a drive roller 209 having a shaft 210 rotatably carried by the extensions. A sprocket 211 is fixed on the shaft 210 and an endless conveyor or belt 212 is supported on the idler roller 206 and the drive roller 209 I so that an upper portion of the belt will ride on the platen 204 of the channel. The plates 205' at the output end of the conveyor may be adjusted to control the tautness of the belt 212. A housing 213 is supported directly under the frame 201 and a split primary shaft 214 is journalled therein and has end sections respectively carrying sprockets 215 and 216, with a member on one. section having a sprocket 217 and large and small gears 217' on opposite sides of the sprocket 217 as depicted in FIG. 20. An electric motor 218, as shown in FIG. 15, is supported on the frame and a speed reducer 219 driven by the motor is connected to the sprocket 217 on shaft 214 by a chain or belt 220 for im parting rotation to the right section of this shaft. A chain or belt 221 connects the sprockets 211 and 215 respectively fixed on the shaft 210 and on a section of the primary shaft 214 so that rotation of the latter will also impart rotation to the drive roller 209 to cause the belt 212 to travel in the direction indicated by the arrows in FIGS. 14 through 18.

The wrapper feed 200 is operatively associated with the input end of the conveyor belt 212 and related structure, and includes an idler roller 222 for the wrapping material and is rotatable on a shaft 223, the latter, as best shown in FIG. 16, having apertured ends through which threaded elements 224 extend and connect with a pair of fittings 225. Each of the fittings is detachably and pivotally supported on an extension 207 by a screw or bolt 226 and a helical spring 227 is carried by each of the elements 224 for disposition between a fitting and a head 228 of an element for biasing or resiliently urging the roller 222 against an unwinded end portion 229 of a roll 230 of plastic wrapper material. A driven roller 231 for the wrapper material has a shaft 232 which is also journalled on the extensions 207. A sprocket 233 is fixed on the shaft 232 and a chain 234 connects sprocket 233 with the sprocket 216 on a left section of the shaft 214. The pivotal positioning and biasing adjustment of the roller 222 may be readily controlled by manipulating the screws 226 and the elements 224. The roller 222 is preferably provided with a plurality of axially spaced annular resilient members 235 for effectively engaging and stabilizing the wrapper material as it is being fed to the conveyor 212. As shown in FIG. 15, a roll 230 of wrapper material of a greater or lesser width than the roll 230 may be utilized in lieu of the latter.

Attention is directed to the fact that an antireverse mechanism is preferably embodied in the driven roller 231 for the strip of wrapper material. This mechanism may be designed and constructed in any mode desired, but as shown in FIG. 22, includes an annular member 236 which is fixed on the shaft 232 and provided with circumferentially spaced peripheral notches 237 which respectively loosely receive brake or clutch members in the form of rollers 238. A ball bearing assembly 239 is carried by the shaft 232 and is housed in the roller 231. This roller is also provided with an end wall 240 and a ring element 241 which is fixedly secured in the roller and has an internal annular braking surface which may be engaged by the members 238 whereby to permit free-wheeling or rotation of the roller in one direction as indicated by the arrows in FIGS. 16, 17, and 18, and prevents reverse rotation of the roller 231 in an opposite direction and backrunning of the wrapper roll 230.

The roll 230 of wrapper material has an insert 242 through which a shaft 243 extends. This shaft has ends which are journalled in bearings 244 mounted on parallel arms 245 extending outwardly from the legs 203 of the frame. The bearings are preferably of a split character so that upper parts 246 thereof may be selectively adjusted and clamped against the ends of the shaft by manipulating wing nuts 247 for controlling the friction between the shaft and bearings whereby the outflow of the material may be regulated to prevent overrunning thereof.

The right ends of the side walls 205 of the channel 201 are also preferably provided with a pair of parallel uprights 248 which are preferably vertically and detachably adjustable in a vertical plane by a pair of screws or bolts 208 having shanks which extend through slots 249 in the uprights and connect with the side walls 205 of the channel 201 as shown in FIGS. 15'

and 16.

The idler roller 250, above referred to, is similar to the idler roller 222 and has ends extending through vertical slots in the uprights 248 for support in the same manner as the ends of the idler roller 222 for adjustably biasing the roller 250 downwardly so that annular resilient members thereon will engage the end portion 229 of the wrapper material and the latter against an upper portion of the endless conveyor belt 212. Thus, the wrapper material, as it unwinds from the roll 230, is resiliently supported between the idler roller 222 and the driven roller 231 and also between the idler roller 250 and the belt 212. This unique arrangement, among otherthings, serves to effectively stabilize and move the material forwardly on the belt 212 and maintain a portion of the material between the idler rollers 222 and 250 relatively taut and particularly on intervening area 229' in an inclined condition for severance or cutting by a cutter device generally designated 251. It should be observed that the drive roller 209 is so mounted that a portion of the belt 212 carried thereby is supported in an elevated or inclined position relative to the platen 204 between the roller 209 and idler roller 250 and serves as a resilient support or cushion for the area 229' of the wrapper material and thereby facilitate cutting of the material by the cutter device.

Attention is directed to the important fact that the speed of the idler roller 250 induced by the forward motion of the belt 212 is greater than that of the driven roller 231 and idler roller driven thereby and this difference in speed is what causes the spacing between the wrappers or sheets resulting from the periodic cutting 1 of the strip material by the cutter device. More specifically, the diameter of the idler roller 250 and speed of the conveyor 212 is greater than the diameter and speed of the driven roller 231 and this accounts for the spacing between the wrappers, which spacings correspond in number to the number of revolutions of the cutter device. The rollers 222 and 231 constitute the means for feeding the strip to the conveyor and the conveyor and idler roller 250 constitute the means for advancing the wrappers on the conveyor. The cutter device 251 preferably employed for severing or cutting the wrapper material into wrappers, pieces or sheets 252 of predetermined rectangular size may be designed and constructed in various ways. As depicted in FIGS. 15 through 19, more specifically, the device preferably includes a solid stainless steel shaft 253 having extremities which are rotatably supported on the uprights 248. This shaft is operatively connected by a chain 254 to a split or sectionalized shaft 255 which is rotatably mounted in a pair of supports 256 which in combination a support 256' also support the sections of shaft 214 above referred to. The cutter device 251 also preferably includes a relatively heavy bar 257 of rectangular cross-section which is secured to the shaft 253 by screws 258 which extend diametrically through the shaft and into the bar as depicted in FIG. 19. The

bar is generally referred to in the trade as a heat sink" and is made of aluminum for heat retention. Insulating means, such as a mass or layer of asbestos 259 is interposed between the shaft and bar. An elongated strip 260 of material, preferably of steel and rectangular in cross-section, is detachably secured by screws 26], or equivalent means, to the left side of the bar 257 as viewed in FIG. 19. This strip or straight edge constitutes a cutting blade which extends a predetermined distance below a lower edge of the bar and is preferably coated with Teflon so that at least an edge 260 is covered thereby. An insulated electric heating element 262 is preferably secured lengthwise against an outer or left face of the strip 260 by clips 263 and screws 261 which extend through the clips and strip and into the bar. This element serves to impart heat to the strip and its retention and stabilization in the bar 257.

As best illustrated in FIGS. 20 and 21, a pair of axially spaced annular commutators 264 are fixedly secured to one end of the shaft 253 and insulated therefrom by insulator sleeves 265. A pair of insulated conductors 266 are respectively secured to the ends of the heating element 262 and to the commutators 264. One of the conductors is preferably comprised of two pieces which are connected to a thermostatic switch TH266 secured to the back of the bar 257, as shown in FIG. 17, for controlling the current to the heating element and maintaining the bar at a substantially uniform temperature. A block 267 of insulation is secured to one of the uprights 248 and a pair of yieldable contacts 268 are carried thereby and respectively engage the commutators. These contacts are connectible with a source of electricity through conductors 651 and a switch S on a panel of the control unit 600 for operating the heating element 262.

The cutter device 251, during each revolution in the clockwise direction depicted in P16. 16, causes the edge 260' to intermittently transversely engage the strip of wrapper material 229 at the inclined area 229' as it is uncoiled upon the belt 212 and thereby cut the material by melting to provide the wrappers 252 which are of corresponding size. When the edge 260 of the blade 260 engages the wrapper material the inclined portion of the belt 212 thereunder may slightly yield so as to promote the cutting of the material. The temperature of the blade or strip 260 and bar 257 is preferably such that the material will be instantaneously melted or disintegrated when the edge 260 of the strip touches the material.

As alluded to above, the speed of the belt 212 is somewhat greater than that of the speed of the material advanced by the rollers 231 and 222 so that the wrappers as cut will be caused to successively advance at a sufficient rate or speed to effect a substantially equal spacing therebetween and locate them on the belt for successively receiving the products as they are directed substantially onto one half, of the areas of the wrappers as shown in FIG. 14. It is important that the products be centered or placed at predetermined locations on the wrapper so that when the latter is folded, sufficient portions thereof will extend laterally of the product for shrinking and completely sealing each of the products in a wrapper as evidenced in FIG. 32.

Referring further to the control system depicted in FIG. 20, the split shafts 214 and 255, above referred to,

are connected by gears 269 and the shaft 214 is provided with a clutch 270 operable by a solenoid 270 and the shaft 255 with a clutch 271 operable by a solenoid 271'. A split shaft 272 is rotatably supported in a position transverse to the shaft 214 and has a gear 273 which engages the smaller of the gears 217 on the shaft 214. Theshaft 272 is also provided with a clutch 274 operable by a solenoid 274' and with a sprocket 275 which is adapted for connection by a chain or belt 276 with a drive shaft 328 of the conditioner 300 as depicted in FIG. 9. The larger gear 217' on the shaft 214 is connected to a gear 277 of a variable speed drive or changer 278. This changer is provided with a cam 279 which actuates a switch S280 and has a control 280' for manually adjusting the changer. The cam 279 associated with the changer 278 is operated by an output shaft of the latter. The output speed is manually controllable by the control 280 so that the periodicity of the operation of the cutter device 251 determines the required size or length of the wrappers. The switch S280 is connected by three conductors 281, 282 and 283 to a timer assembly 285" and to the solenoid 271 by a conductor 284. The timer assembly, which may be regulated by a manual control 285' through timer 285, is also connected to the solenoid 274' by a pair of conductors 286 and to a switch S296 by conductors 294. The switch S296 is connected to the control box 53 of the dispenser by the conductors 57. A pair of primary or input conductors 287 from a source of electricity are connected to a switch S2 on the control unit 600. This switch is connected by conductors 288 to a transformer T and conductors 286 connect this transformer to the timer assembly 285". The switch S2 is also connected by conductors 290 to a switch S12 and the latter is connected to the switch S3 by a conductor 293 and 291 and to the solenoid 271' by a conductor 299. The switch S3 is connected to the solenoid 270' by a conductor 293'. The timer 285 enclosed in timer assembly 285" serves to control the amount of delay between the time the switch S280 is energized and the clutch 274 is activated so that the product being discharged from the conditioner 300 will be correctly located or centered on a predetermined area of the wrapper 252.

The timer 285 is manually adjustable by the control 285 to provide a range of 0.5 to 5 seconds delay between the time that the switch S280 is closed and the time that the solenoid 274 is energized. This adjustment offers a unique setup whereby each product is caused to fall substantially in the center of one-half of each wrapper irrespective of the size of the wrapper or product. As the clutch 274 is completing its cycle, or revolution, the pin 297 on the movable component 295 of the clutch 274 will close the switch S296 to restart the motor 29 of the dispenser, only when the conditioner is inoperative or at rest, to cause another one of the products in the row backed by the mover 46 to travel forwardly and down the apron 48 until the dispenser is again stopped by actuation of the switch S49.

Each of the clutches 270, 271 and 274, above referred to, is preferably of a single revolution type in which one component 295 of each clutch is fixed to a section of each of the split shafts and its other component 295' is rotatable with respect to the fixed component and provided with a pin or abutment 297 for

Claims (39)

1. A system of the kind described comprising elongated conveyor structure, means adjacent one extremity of saId structure for successively delivering sheets of wrapping material thereon for transport, means for automatically successively depositing products in predetermined positions on said sheets, means intermediate the length of said structure for moving substantially one half portion of each sheet over each product and a lower substantially one half portion of the sheet, and means adjacent the opposite extremity of said structure and spaced from said intermediate means for automatically joining said portions whereby a product will be sealed within the confines of each sheet during the period the product is in said predetermined position.

2. A system of the character described comprising a conveyor structure having an input end and an output end, means for delivering a substantially transparent wrapper onto said input end, means for automatically depositing a product in a predetermined position on a face side of the wrapper whereby marginal edge portions of the wrapper project laterally from the product, means disposed intermediate said ends whereby another face side of the wrapper may be directed against the product and marginal edge portions of this face are disposed opposite said first-mentioned edge portions, and means disposed adjacent said output end and spaced from said intermediate means for joining said edge portions whereby to substantially confine the product while it is so positioned.

3. The system defined in claim 2, in which the means for depositing the product comprises an inclined conveyor which successively places the product onto the wrappers in timed relation with said wrapper delivering means.

4. The system defined in claim 2, in which said wrapper delivering means includes a support for a roll of the wrapper material and means for unwinding and cutting a roll into wrappers and successively placing them onto said input end, including means for defrosting at least a portion of each product prior to its deposit on a wrapper.

5. The system described comprising: means for defrosting a product and a conveyor associated therewith, a dispenser for accommodating and selectively feeding frosted products to said conveyor for transport thereby for subjection by said defrosting means for removing the frost, an elongated conveyor having an input end disposed adjacent said defrosting means and also having an output end, means for unwinding and cutting a roll of heat shrinkable wrapping film into wrappers and successively placing them onto said input end, means arranged alongside said elongated conveyor for moving a portion of each wrapper upon each product in overlapping relationship thereto whereby to partially cover the same, and means disposed adjacent said output end for receiving and applying heat to said wrappers for shrinking and fusing portions thereof whereby to completely wrap and seal each product in a wrapper.

6. A system for the purpose described comprising: an elongated conveyor having an input end and an output end, means for feeding sheets of heat shrinkable and fusible wrapper film onto said input end, means for defrosting a frosted product and selectively depositing the same onto said sheets, a dispenser for accommodating and selectively conveying the frosted products to said defrosting means for removing the frost therefrom, a former extending longitudinally above said conveyor between its ends, means disposed between said ends for directing air against each sheet for folding a portion thereof over said former and onto each product whereby to partially wrap the latter, a chamber disposed adjacent said output end, conveyor means extending through said chamber for receiving each partially wrapped product from said elongated conveyor and transporting it through said chamber, and means in said chamber for forcing hot air against each sheet whereby portions thereof will shrink and shrivel and fuse together and bear against each product for sealing the same in said sheet.

7. The system described comprising: an elongated conveyor, means for selectively depositing one-piece wrappers of heat shrinkable and fusible material on one end of said conveyor, means for placing a product of a predetermined size substantially centrally on a planar one-half of each wrapper so that portions thereof extend laterally of the product, means for folding the other planar half of each wrapper onto the product so that portions of this half also extend laterally of the product whereby to partially wrap the same, a heat chamber located in longitudinal relation to said elongated conveyor, a pair of conveyor belts having portions extending through said chamber for receiving and engaging the partially wrapped products therebetween for transport through said chamber when received from said elongated conveyor, and means disposed in said chamber on opposite sides of the products for directing hot air in substantially parallel streams against the lateral portions of the wrappers from locations on opposite sides of said belt portions for shriveling, shrinking and fusing said lateral portions for respectively sealing the products in said wrappers.

8. The system described comprising: an elongated first conveyor having an input end and an output end, means adjacent said input end for longitudinally feeding heat shrinkable and fusible wrappers in a flat condition onto said input end, means disposed transversely of and adjacent said input end for removing frost from a frosted product, a second conveyor associated with said removing means, a dispenser conveyor disposed adjacent said second conveyor for accommodating frosted products and selectively feeding them to said second conveyor for transport by the latter for treatment by said removing means whereby to remove the frost and depositing each product substantially centrally on one-half of each wrapper so that portions of this half extend laterally of the product, means arranged between said input and output ends for automatically causing the other half of each wrapper to bend over and engage the product and so that portions thereof will extend beyond the product in opposed relation to said first-mentioned lateral portions while the products and wrappers are being transported by said first conveyor, and means adjacent said output end for heat treating all of said lateral portions of each wrapper to shrink, shrivel and fuse the same whereby to completely enclose and seal each product in a wrapper.

9. The method described which comprises arranging a product between opposed face portions of fusible wrapper material so that free edge portions of the face portions project laterally of the product, and then subjecting said edge portions to hot air currents flowing in opposite directions against said edge portions while limiting the exposure of said face portions to these currents whereby to unite said edge portions to define a rib conforming to the shape of the product for sealing the product in said wrapper material.

10. A method of wrapping and sealing a product in a plastic wrapper which comprises: delivering a heat shrinkable and fusible plastic wrapper which is larger than the product onto a support therefor, depositing a product centrally on one-half of said wrapper, blowing the other half of said wrapper upon said product, and heating free edge portions of said halves to effect shriveling shrinking and fusion thereof to completely wrap and seal the product in the wrapper and provide an external tearable rib whereby to facilitate removal of the wrapper from the product when desired.

11. A method which comprises conveying a frosted product, defrosting the product by applying fluid thereto while it is being conveyed, depositing the defrosted product in a predetermined position on a sheet of heat shrinkable film, partially wrapping the sheet about the product so that portions of the sheet extend laterally of the product, and then subjecting the partially wrapped product while being conveyed to heat at a predetermined temperature for a predetermined period of time to cause shriveling, shrinking and fusion of said lateral portions in conforming relationship to said product to seal the product in said sheet.

12. A method of wrapping which comprises depositing a one-piece sheet of fusible wrapper material on a first movable conveyor, depositing and centering a product substantially on a planar one-half of the sheet so that free edge portions of the sheet will extend laterally from the product, folding the other half of the sheet upon the product so that its upper free edges also extend laterally from the product in opposed relationship to said first-mentioned edges, moving the folded sheet and product from the first conveyor to and between a pair of conveyors for transport thereby, and directing hot air against said free edges while the product and sheet are conveyed by said pair of conveyors to fuse said edges and define a sealing rib conforming to the shape of the product.

13. A method which comprises depositing a product centrally on one-half of a substantially square unsecured one-piece sheet of heat shrinkable and fusible film so that edge portions of this half project beyond the product, folding the other half portion of the film onto the product so that edge portions of this half project beyond the product to partially wrap the product, transporting the partially wrapped product between a pair of belts through a chamber with the fold and edge portions opposite the fold being positioned on opposite sides of the medial line of travel, and then blowing hot air from spaced positions in the chamber at opposite sides of said medial line for flow between said belts and against said fold and edge portions of each sheet whereby to shrink, shrivel and fuse said edge portions and portions of said fold in conforming relation to each product to seal the product therein and form an external tearable rib.

14. A method of confining a product in a transparent one-piece fusible wrapper which comprises initially depositing the product substantially on a planar one-half of the wrapper, automatically folding substantially the remaining half of the wrapper over the product and said one-half, and then fusing all opposed free edge portions of the halves to seal the product in the wrapper and provide an external tearable rib conforming to at least a portion of the contour of the product.

15. A sealer for the purpose described comprising a frame supporting an insulated heat chamber, a pair of imperforated conveyors for jointly engaging and carrying a product partially wrapped in a folded sheet of fusible material through said chamber to cause opposed edge portions of the material to fuse and thereby seal the product in the material, and means for cooling one of the conveyors at a location externally of said heat chamber.

16. The sealer defined in claim 15, in which the cooled conveyor has a cross-sectional dimension greater and its operative length is less than that of the other conveyor.

17. A sealer for the purpose described comprising a pair of conveyors for supporting and jointly carrying therebetween a product disposed in a folder having fusible free edge portions extending laterally from the product, and a pair of elongated units disposed diagonally on opposite sides of said conveyors for directing hot air therebetween and against said edge portions to fuse the latter and form an external rib extending from the ends of the fold of the folder which conforms to the product and seals the latter in the folder and so that air from one unit will flow back into the other unit for recirculation and direction to the one unit.

18. The sealer defined in claim 17, in which said elongated units include heating elements, means whereby the heating elements may be adjusted to maintain a substantially uniform temperature of hot air, fans for blowing the hot air, including means for controlling the operation of the fans whereby a substantially uniform velocity of hot air may be maintained, means for controlling the operation of the conveyors, and control means wherebY if the fans are not turned on and the heating elements are and the temperature of the hot air rises above a predetermined value the fans and the conveyor will be automatically rendered operative.

19. A sealer for the purpose described comprising a frame provided with a chamber, a lower conveyor and an endless upper conveyor arranged so that a lower portion of the latter will cooperate with said lower conveyor in a manner whereby products which are individually partially wrapped in fusible sheet material may be carried therebetween and through said chamber, means for directing hot air against the material while the products and material are travelling through such chamber whereby to fuse the material to confine and seal each product in the material, and means located above the chamber for cooling the upper conveyor.

20. A heating structure of the character described comprising: a chamber, a pair of means disposed diagonally in said chamber for circulating hot air substantially from one means to the other in a generally rectangular pattern, and conveyor means interposed between said pair of means for transporting a product partially covered by a heat shrinkable film for travel through said chamber for shrinking and sealing the film about the product.

21. A heating structure of the character described comprising: a chamber, a pair of means disposed in said chamber for circulating hot air substantially from one means to the other in a generally rectangular pattern, a conveyor for transporting a product partially covered by a heat shrinkable film for travel through said chamber for shrinking and sealing the film about the product, an endless conveyor having a lower portion which is cooperable with said first-mentioned conveyor whereby to assist in conveying the partially covered product through said chamber, and means for cooling an upper portion of said endless conveyor at a location above its lower portion.

22. In combination: a chamber, a conveyor in said chamber, and a pair of means disposed in said chamber on opposite sides of said conveyor for blowing hot air diagonally across said conveyor and so that the air from each means will be substantially received by the other means within the confines of said chamber.

23. A prewrap assembly comprising an elongated former, blower means disposed alongside said former for blowing air thereacross, and a conveyor for carrying a flexible wrapper having a product disposed on substantially one-half portion thereof alongside said former so that air will fold the other half portion over the former and onto the product.

24. A prewrap assembly comprising a blower adapted to be positioned adjacent to a conveyor for emitting a blast of air against a wrapper to fold a portion thereof against a product disposed on the wrapper, conduit means extending from said blower for connection with a source of pressure, a solenoid operable valve interposed in said conduit means, and electrical means operatively connected to said solenoid and being responsive to actuate said solenoid to open said valve so that air will flow to said blower when the product and wrapper have been conveyed to a predetermined position with respect to said blower.

25. The prewrap assembly defined in claim 24, including a pair of valves interposed in said conduit means between said blower and said solenoid operable valve for controlling the periodicity of the blasts, and means operable in conjunction with one of said pair of valves for controlling the periodicity between the blasts.

26. The prewrap assembly defined in claim 24, including a second conveyor disposed in a relatively close spaced end relationship to said first-mentioned conveyor, and a second blower connectible to said source serving to blow air upwardly into said space to prevent the wrapper from falling into this space when it and the product are travelling thereover.

27. An airlift for wrapper material comprising a pair of conveyors disposed in a relatively close spaced end-To-end relationship and in the same horizontal plane for carrying a sheet of wrapping material having a product thereon from one conveyor to the other, and means for directing air upwardly in said space whereby said air provides the sole means whereby to maintain said sheet in a substantially horizontal plane and prevent the same from falling into said space while the product and sheet are travelling thereover on said conveyors.

28. An airlift for wrapper material comprising in combination: a first conveyor and a second conveyor disposed in a relatively close spaced end relationship to said first conveyor, an elongated former extending longitudinally in relatively close overhead parallel relationship to said first conveyor, means for imparting motion to said first conveyor for transporting a flexible wrapper having a product on substantially one-half portion thereof alongside said former, means located adjacent said former whereby air may be directed against another portion of the wrapper to cause it to engage said former and fold thereover onto the product, means imparting motion to said second conveyor, and means whereby air may be directed upwardly into said space between said conveyors to prevent the wrapper from falling into the space while the product and wrapper are travelling thereover.

29. A machine for wrapping a frozen product comprising: means for defrosting at least a portion of the product for modifying the appearance of this portion as compared to the remainder thereof, means for arranging a plastic wrapper and the product so that the latter is partially confined in the wrapper, and means for uniting portions of the wrapper whereby to seal the product therein and cause the wrapper to be drawn intimately against portions of the product.

30. The machine defined in claim 29, in which said defrosting means comprises a fluid which engages the product to provide a layer of moisture on said portion, and the wrapper is substantially transparent so that the said portion of the product is visible therethrough and the moisture serves to bond the wrapper to the product when the wrapped product is refrozen.

31. The machine defined in claim 29, in which the modified portion of the product is flat and the uniting of the wrapper portions for sealing is obtained by shriveling and shrinking such portions in conforming relation to at least a part of the product and other portions intimately against said modified portion.

32. A method of wrapping a product which comprises: moistening a frozen food product by a liquid for restoring its natural appearance, arranging a thin plastic transparent wrapper and the product so that the latter is partially confined in the wrapper, uniting portions of the wrapper for sealing the product therein and so that the product is clearly visible through at least a portion of the wrapper, and then refreezing the wrapped product so that the liquid serves to bond the wrapper thereto.

33. A method which comprises: defrosting at least a portion of a surface of a frosted product to remove the frost therefrom and provide a film of moisture thereon, arranging a wrapper of heat shrinkable film and the product so that the product is partially wrapped and portions of the wrapper extend laterally of the product, subjecting the lateral portions to heated air at a predetermined temperature and velocity for a period of time sufficient to cause said lateral portions to shrivel, shrink and fuse in conforming relationship to at least a part of the product and seal the product in the wrapper, and then refreezing the wrapped product so that the film of moisture will bond the wrapper to such surface.

34. A method which comprises conveying a frosted product, applying a fluid to the product to defrost at least a portion thereof while it is being conveyed, arranging a heat shrinkable transparent wrapper and the product so that the latter is partially wrapped and portions of the wrapper extend laterally of the product, and then subjecting the lateral portions tO heated air at a predetermined temperature and velocity for a period of time sufficient to cause shriveling, fusion and shrinking of the same to seal the product in the wrapper and so that the defrosted portion is clearly visible through the wrapper.

35. A sealer for the purpose described comprising a frame provided with a first platen and a first pair of rollers, a first endless conveyor belt carried by said rollers so that an upper portion of the belt will always be supported for movement on said platen, a second platen mounted above said first platen and a second pair of rollers carrying a second endless conveyor belt so that a top portion of this belt will always be supported on said second platen and a lower portion thereof will be freely movable in a relatively loose manner whereby products which are partially wrapped in fusible sheet material may be inserted for engagement by said upper and lower portions of said belts for joint transport thereby, means disposed above and engaging said top portion of said second belt for stabilizing its relation with said second platen, a heat chamber, and means in said chamber whereby hot air may be directed against the sheet material to fuse portions thereof to seal the product in the material.

36. The sealer defined in claim 35, in which the upper belt is constructed from relatively thick heavy non-porous material and its lower portion is adapted to engage the lower belt when products are not being conveyed thereby.

37. The sealer defined in claim 35, in which a second chamber is disposed above said heat chamber, said second platen is located in said second chamber, a plurality of spaced longitudinally extending heat dissipating fins extend downwardly from said second platen, and means are provided for directing air between the fins and against second platen whereby to assist in cooling the same including said upper belt when travelling thereon.

38. A heating structure of the character described comprising: a chamber, means for conveying a product partially covered by a heat shrinkable film through said chamber, a pair of means disposed in said chamber on opposite sides of said conveyor means for heating air, means offering adjustment of said heating means whereby a predetermined substantially uniform temperature of the air may be maintained, means for forcing the heated air to flow at substantially a uniform velocity across said conveyor means to cause the film to seal the product therein, and means for controlling the operation of said conveyor means, said heating means and said forcing means and so that said heating means will not damage the structure if the temperature of the heated air exceeds a predetermined limit.

39. A heating structure of the character described comprising: a chamber, means for conveying a product partially covered by a heat shrinkable film through said chamber, a pair of means disposed in said chamber on opposite sides of said conveyor means for heating air, means offering adjustment of said heating means whereby a predetermined substantially uniform temperature of the air may be maintained, a pair of fans associated with said heating means, means offering adjustment of said fans whereby a substantially uniform velocity of heated air may be maintained for flow against the film for sealing the product therein when transported by said conveyor means, and means for controlling the operation of said conveyor means, said heating means and said forcing means and whereby if the heating means are operating and the fans are not and the temperature of the heated air exceeds a predetermined value the fans and conveyor means will be automatically rendered operative.

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