US3808767A

US3808767A - Methods of and apparatus for shrink packaging

Info

Publication number: US3808767A
Application number: US00281153A
Authority: US
Inventors: L Reid
Original assignee: MASTER PACKAGING EQUIPMENT Inc
Current assignee: MASTER PACKAGING EQUIPMENT Inc; SPX Flow Technology Systems Inc
Priority date: 1971-01-11
Filing date: 1972-08-16
Publication date: 1974-05-07
Anticipated expiration: 1991-05-07

Abstract

Methods of and apparatus for shrink packaging articles in a heat-sealable, heat-shrinkable plastic film wrapper, in which the wrapper is heated for heat-sealing and heat-shrinking purposes, and portions of the wrapper are folded as well as being heatsealed by blowing heated air thereon.

Description

United States Patent 1191 Reid 1451 May 7,1974

1 1 METHODS OF AND APPARATUS FOR 3,608,713 9 1971 Crosby 198/183 x SHRINK P CK G 3,378,989 4/1968 Den'ker 53/184 3,553,935 1/1971 Woods 53/209 [75] Inventor: Laurie M- R d, m g 3,430,358 3/1969 Denker 34/225 x 3,389,530 6/1968 Yates 53/30 [73] Awgme' Masteilpackagmg Equ'pmem 3,371,462 3/1968 Nordkvist et a1. 53/33 Truss 3,309,835 3/1967 Peppler 53/30 1 I l 7 3,123,955 3/1964 Weissensee et al 53/30 [22] Filed Aug 16, 9 2 3,110,232 11/1963 Frei 93/84 FFX [21] Appl. No.: 281,153 2,638,724 5 1953 Harvey 53/33 i i Application Data Primary ExaminerTravis S. McGehee [63] lC9o;1]t1nu;t1odn-m-:art of Ser. No. 105,318, Jan. 11, Assistant Examiner l sipos am one Attorney, Agent, or Firm-Koerrig, Senniger, Powers 52 US. Cl 53/30, 53/33, 53/184, and

' 53/375 51 1111. c1.... B65b 51/20, B65b 53/06 [57] ABSTRACT [58] Field of Search 53/30, 33, 34, 184, 375; Methods of and apparatus for shrink packaging arti- 34/162, 225, 233; 93/84 FF, 156/196, 226, cles in a heat-sealable, heat-shrinkable

plastic film

227, 85, 86, 497, 499 wrapper, in which the wrapper is heated for heatsealing and heat-shrinking purposes, and portions of [56] References Cited the wrapper are folded as well as being heat-sealed by I E STATES P T I blowing heated air thereon.

3,399,506 9/1968- Howe, Jr 53/30 X 44 Claims, 27 Drawing Figures (13 H7 /9 II '/7 l 2| A? z/fl/k/v .s I?

' 1 A 1 j I 1 1 l9 J .J/

PATENTEDm 7 e914 WEE? Q2 U? 57 m awe Q Q N mm v m w R: Kw 8: 8; Lu m -FT'WHFI ,m 6:? ..|Ll @lmiwlm A hm All muml 7 1 mm kw PMENTED MAY 7 I974 SHEET 05 0F 30 Pmmmmv mm 3808367 saw a HF w FIGZ5 METHODS OF AND APPARATUS FOR SHRINK PACKAGING CROSS-REFERENCE TO RELATED APPLICATION BACKGROUND OF THE INVENTION This invention relates to shrinkpackaging, and more particularly to methods of and apparatus for packaging 7 articles in heat-scalable, heat-shrinkable plastic film wrappers.

The invention is especially concerned with new and improved methods of and apparatus for folding over and heat-sealing portions of a wrapper placed around wrapper, as well as problems in adjustment of the apparatus to handle ar ticlesof different sizes arid shapes.

SUMMARY OF THE INVENTION Among the several objects of this invention maybe noted the provision of improved and simplified methods of and an apparatusfor packaginganarticle or articles in a heat-sealable, heat-shrinkable plastic film wrapper which eliminate anynecess'ity for complicated mechanical folding arms or the like; the provisionof such methods and apparatus which simply utilize the same hot air as is used to heat the film for shrinking for effecting folding and heat-sealing operations on the wrapper, eliminating any necessity for separate heatsealing and heat-shrinking operations such as heretofore used; and the provision of apparatus such as described which is readily adjustable to handle work of different shapes and sizes.

In general, the method of this invention comprises wrapping one or more articles constituting the work to be packaged in a heat-sealable plastic film with part 'of the film constituting an outer flap adapted to be folded over upon the outside of and heat-sealed to another part of the film to close the wrapping. Heated air is blown against'the said outer flap in a direction such as to fold it over upon said other part of the film and also to heat it and press it against said other part of the film to cause it to become heat-sealed thereto.

Apparatus of this invention generally comprises means for conveying an item of work along a predetermined path with the work enwrapped in 'a heatsealable, heat-shrinkable plastic film with part of the film constituting the aforesaid outer flap, with means located along said path for blowing heated air against the said outer flap in a direction such as to fold it over upon said other part of the film and also to heat it and press it against said other part ofthe film to cause it to beocme heat-sealed thereto.

Other objects and features will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION oF THE DRAWINGS FIG. 1 is a perspective showing an article enwrapped in a wrapper in accordance with a first embodiment of the method of this invention;

FIG. 2 is a view in elevation of FIG. 1 as viewed from either its left or right side;

FIG. 3 is a section on line 3-3 ofFIG. 2 showing certain lower flaps folded up on the outside of the twoopposite sides of the article in accordance with said first embodiment of the method of this invention;

FIG. 4 is a view corresponding to FIG. 3 showing certain upper flaps folded down on the outside of the opposite sides of the article and overlapping the folded-up lower flaps in completion of the first embodiment of the method of this invention;

FIG. 5 is a vertical longitudinal section through a first embodiment of apparatus made in accordance with this invention utilizing the first embodiment of the method of thisinvention;

FIG. 6 is an enlarged vertical transverse section on line 66 of FIG. 5;

. FIG. 7is a view showing details of a shutter of the apparatus;

FIG. 8 is a vertical transverse section on line 88 of FIG. 5;

FIG. 9 is a horizontal section on line 99 of FIG. 6, on the scale offFIGS. 5 and 8;

' FIG. 10 is a plan of the apparatus, with parts broken away;

FIG. 11 .is a perspective showing an article en wrapped in a wrapperin accordance with a second embodirnent of the method of this invention;

FIG. 12 is a section on line 1 2l2 of FIG. 11;

FIG. 13 is a section on line 13-13 of FIG. 12;

FIG. 14 is a view corresponding to FIG. 11 showing certain parts of the end portions of the wrapper in an initial folded condition;

FIG. 15 is a section on line l515 of FIG. 14;

FIG. 16 is a rightend view of FIG. 15 showing parts of the end portions of the wrapper in a further folded condition;

FIG. 17 is a section on line 17l7 of FIG. 16;

FIG. 18 is a view corresponding to FIG. 16 showing the completed wrapping; A

FIG. 19 is a section on line l9--l9 of FIG. 18;

FIG. 20 is a perspective showing an article to be packaged applied to a bottom sheetconstituting a por tion of a wrapper in accordance with another method of this invention;

FIG. 21 is a view corresponding to FIG. 20 showing a cover placed in inverted position over the article and extending down its sides;

FIG. 22 is a view corresponding to FIG. 21 showing a portion of the bottom sheet at the: front end of the article folded up in accordance with this invention;

FIG. 23 is a view corresponding to FIG. 22 showing other portions of the bottom sheet being progressively folded up along the sides of the work; I

FIG. 24 is a view corresponding to FIG. 23 showing a portion of the bottom sheet at the rear end of the work folded up in accordance with this invention;

FIG. 25 is a vertical longitudinal section through a second embodiment of apparatus of this invention for carrying out the method of FIGS. 20-24;

FIG. 26 is a vertical transverse section on line 26-26 of FIG. 25; and

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIGS. 1 and 2 of the drawings illustrating a first embodiment of the method of this invention, there is indicated at A an article of box-like form constituting the work to be packaged. Two opposite sides of the article (which may be regarded as its ends) are each designated 1. Two other opposite sides of the article which may be regarded as its front and rear sides are each designated 3. The top and bottom of the article are designated 5 and 7, respectively. In accordance with this invention, the article is enwrapped in a wrapper 9 of heat-scalable, heat shrinkable plastic film, such as a heat-shrinkable polyethylene film. Wrapper 9 is initially in the form of a tube or sleeve around the article and has end portions each generally indicated at 11 extending beyond the opposite side or end faces 1 of the article. The wrapper comprises a top sheet 13 of film overlying the top of the article and folded down upon the front and rear sides 3 of the article, and a bottom sheet 15 of film underlying the bottom of the article and folded up upon the front and rear sides 3 of the article, with these top and

bottom sheets

13 and 15 joined together at their edges at the front and rear sides 3 of the article by heat-sealed seams each designated 17. The article A may be enwrapped in the tubular wrapper by means of a wrapping machine presently on the market sold under the trademark SLEEVEMAS- TER by Master Packaging Equipment, Inc., of Trussville, Alabama. Essentially, in this machine, the article is fed by a conveyor in between two webs'of plastic film joined at their forward ends by a heat seal 17, and then the webs are sealed together by another seal 17 at the back of the article and severed to form the tube or sleeve 9 enwrapping the article. The webs are wider than the article so that the end portions 11 extend beyond the opposite sides or ends 1 of the article. Any other suitable means for forming the tube or sleeve 9 around the article may be used.

As shown in FIG. 1, the top sheet 13 is preferably wider than the bottom sheet 15 so that the end portions of the top sheet extend out beyond the ends of the bottom sheet. The section of each end portion 11 indicated at 19 including the bottom part of the end portion of the bottom sheet constitutes an inner end flap adapted to be folded up against the respective side or end 1 of the article, and the section 21 of each end portion 11 including the top part of the end portion of the top sheet 13 constitutes an outer end flap adapted to be folded down upon the respective side or end 1 of the article with its lower margin overlapping the upwardly folded lower inner end flap 19.

In accordance with the first embodiment of the method of this invention, heated air is first blown upwardly against end portions 11 of the wrapper 9 asshown in FIG. 3 (wherein the arrows indicate the air flow) to fold the inner (lower) end flap sections 19 upwardly against the side or end faces 1 of the article A, and to effect heating of these inner end flaps 19 to a temperature sufficient for heat-sealing of the plastic film of which the wrapper is formed. This also heats the film for shrinking. Subsequently, heated air is blown inwardly and downwardly against the outer (upper) end flap sections 21 of the wrapper 9 as shown in FIG. 4 (wherein the arrows indicate the air flow) to fold these flap sections 21 downwardly against the side or end faces 1 of the article A and against the outside of the previously upfolded flap sections 19, and to effect heating of these outer flap sections to a temperature sufficient for heat-sealing thereof to flap sections 19. The air also presses the lower portions of flap sections 21 against the outside of flap sections 19 (which are also heated) to cause these to become heat-sealed together as indicated at 23 in FIG. 4. As

wrapper flaps

19 and 21 are respectively blown against the sides 1 of article A as shown in FIG. 4, corner folds (not shown) are formed at each corner of the article. The heated air blown over the article, as depicted by the arrows in FIG. 4, folds these corner folds against other parts of the wrapper, presses them against the wrapper and heat-seals them thereto. This stream of heated air additionally heats the film for effecting shrinking of the wrapper 9 on the article A (the work).

FIGS. 510 illustrate an apparatus made in accordance with this invention for carrying out the first embodiment of the method of this invention as above described. As shown, the apparatus comprises means indicated generally at 25 for conveying article A or other item of work along a predetermined path, with means indicated generally at 27 at a first station S1 along this path for blowing heated air upwardly (as shown in FIG. 3) against the end portions 11 of the wrapper 9 to fold the flap sections 19 upwardly against the sides 1 of the article A and also to heat these flap sections, and means indicated generally at 29 at a second station S2 farther along the said path for blowing heated air downwardly (as shown in FIG. 4) against the upper flap sections 21 to fold these down as outer flaps to overlap the flaps 19 and to heat them and press them into engagement with flaps 19 for heat-sealing together flaps 21 and 19.

More particularly, the apparatus comprises a shrink tunnel generally designated T on a base 31 constituted by an elongate cabinet structure. The conveying means 25 comprises an endless conveyor having an upper horizontal reach 25a movable .in the direction of the arrows shown in FIG. 5 (from left to right) for conveying the work through the tunnel from one end thereof constituting its entrance end (its left end as shown in FIG. 5) to its other end constituting its exit end (its right end as shown in FIG. 5), and a lower horizontal return reach 25b. As shown, the conveyor 25 comprises a pair of endless chains each designated 33 trained around sprockets 35 on a horizontal sprocket shaft 37 at the upstream (left) end of the upper reach 25a of the conveyor, and around sprockets 39 on a horizontal sprocket shaft 41 at the downstream (right) end of the upper reach 25a. Extending transversely between the chains are rods 43 spaced at relatively close intervals all around the length of the chains. The spaces between the rods are designated 45; these are narrow enough for supporting the work, and wide enough for upward passage of the heated air at 27. The chains are roller chains, their rollers being indicated at 47. The rods 43 are rotatable on their axes, each rod being tubular and having its ends rotatably received on extensions 49 of the roller pins. Each rod has a sleeve 51 of silicone rubber or other suitable nonstick material to prevent the plastic film wrapper from sticking to the rod. The

sleeve terminates short of the ends of the rod, leaving bare rod end portions 53.

The

sprocket shafts

37 and 41 are journalled at their ends in bearings such as indicated at 55 mounted on bars 57 extending longitudinally of the base cabinet 31 at the top thereof. The shaft 41 constitutes the drive shaft of the conveyor and is adapted to be driven via a chain and sprocket drive 59 from a motor-speed reducer unit 61 mounted in the base 31. The direction of the drive is such as to effect movement of the upper reach 25a of the conveyor 25 from left to right as viewed in FIG. 5. The upper reach 25a of the conveyor is held up against sagging by having the rollers 47 of the chains roll on rails 63 extending longitudinally of the apparatus supported from the bars 57.

The shrink tunnel T has a bottom 65 constituted by a plate spanning the bars 57, sides each generally designated 67 and a top generally designated 69. The sides 67 and top 69 extend beyond the bottom 65 at both ends of the tunnel, which are open for entry and exit of the upper reach of the conveyor and articles being conveyed thereby, and which have fringed curtains such as indicated at 71 for holding heated air in the tunnel. Each side 67 of .the tunnel is of double-walled construction, comprising an inner wall panel 73 and an outer wall panel 75, with insulation 77 in the space between these side wall panels. The top 69 of the tunnel is also of double-walled construction, comprising a lower inner panel 79 spanning the inner side wall panels 73 and an upper outer insulated panel 81 spanning the outer side wall panels 75. The space between these panels constitutes a hot air plenum chamber 83.

The means 27 for blowing heated air upwardly at station S1 comprises a pair of vertical hot air ducts at opposite sides of the tunnel each designated 85 extending downwardly in the space between the tunnel

side wall panels

73 and 75 adjacent one end of the tunnel constituting its entrance end (its left end as viewed in FIGS. 5 and Each duct 85 is in communication at its upper end as indicated at 87 with the plenum chamber 83 and at its lower end as indicated at 89 through the respective inner side wall panel 73 with the interior of the tunnel just above the tunnel bottom wall 65. The inside wall of each duct is formed by the respective inner side wall panel 73. A centrifugal blower 91 .is mounted on the bottom of the upper panel 81. of the top of the tunnel adjacent the entrance end of the tunnel with its inlet in communication via an opening 93 in this panel 79 with the interior of the tunnel. The outlet 95 of the, blower is directed to blow airthrough a heater 97 which may be of the electrical resistance strip heater type for heating the air. The heated air exits from the heater in the direction toward the exit end of the tunnel and is directed back along the sides of the chamber 83 on opposite sides of the heater for entry into the ducts 85 by deflectors indicated at 99 and 101. The blower motor is indicated at M in FIG. 5.

Hot air exiting from the lower ends of the ducts 85 via exit openings 89 flows horizontally laterally inward over the bottom 65 of the tunnel from both sides of the tunnel underneath the upper reach a of the conveyor 25, and is deflected to flow upwardly on opposite sides of the longitudinal central plane of the tunnel by a pair of air deflectors each designated 103, slidable on the tunnel bottom 85. Each of these deflectors 103 comprises a plate having a bent-up curved end 105 adapted to deflect upwardly air flowing in from the respective side of the tunnel over the plate, as indicated by the arrows in FIGS. 3 and 6.

Means indicated generally at 107 is provided for laterally adjusting the deflectors 103 to vary the spacing of their curved ends on opposite sides of the longitudinal central plane of the tunnel for handling work of different sizes. This means comprises a screw member 109 extending horizontally and transversely of the apparatus through one side of the tunnel (its left side as shown in FIG. 6), and the respective duct 85 and opening 89 across the tunnel over the bottom 65 of the tunnel to a bearing 111 adjacent the opposite side of the tunnel. This screw member has a crank handle 113 on its outer end, and oppositely threaded

sections

115 and 117 on opposite sides of the longitudinal central plane of the tunnel. The deflectors 103 have nuts 119 threaded on the

respective screw sections

115 and 1 17, the arrangement being such that on rotating the screw member 109 in one direction, the deflectors 103 are moved toward one another, and on rotating the screw member in the opposite direction, the deflectors are moved away from one another. A center bearing 121 for the screw member is provided on the tunnel bottom plate 65. It will be understood that other suitable means for adjusting the deflectors 103, such as a cable and pulley system, may be used.

The means 29 for blowing heated air downwardly at station S2 comprises a pair of vertical hot air ducts at opposite sides of the tunnel each designated 123 extending downwardly between the tunnel

side wall panels

73 and 75 adjacent the exit end of the tunnel (its right end as viewed in FIGS. 5 and 10). Each duct 123 is in communication at its upper end as indicated at 125 with the plenum chamber 83 and at its lower end as indicated at 127 through the respective inner side wall panel 73 with the interior of the tunnel just above the tunnel bottom wall 65. The inside wall of each duct is' formed by the respective inner side wall panel 73. Adjacent the lower end of each of the ducts 123 is a valve 129 adapted to be closed to cut off flow of hot air through the opening 127 or to be set for a regulated flow of hot air through the opening 127. As shown best in FIG. 8, valve 129 is a butterfly valve actuated by a screw 131 threaded in panel 73. In the upper part of the inside wall of each of the ducts 123 formed by the respective panel 73 are horizontal rows R of air discharge openings 133, four such rows and three such openings in each row being shown. Means is provided for controlling the flow of air through the openings of each row and deflecting it downwardly, the means for each row comprising an elongated shutter 135 having a row of openings 137 therein with these openings spaced the same as openings 133. Each shutter :is mounted for endwise horizontal sliding movement on the inside face of the respective inner side wall panel 73 as by means of bolts 139 secured in the panel 73 extending through elongate horizontal slots 141 in the shutter between a fully open position wherein openings 137 are, in register with openings 133 for full air discharge and a fully closed position wherein the shutter blocks openings 133 to cut off discharge of air therethrough, with a range of intermediate positions for varying the discharge of air through the openings 137. Each shutter 135 also has an inwardly extending downwardly inclined flange 143 at its upper edge for deflecting downwardly air discharged through

openings

133 and 137.

Each of the ducts 85 at station S1 is provided with a butterfly valve 129, discharge openings 133, and shutters 135 the same as those provided for ducts 123 at station S2.

Means is provided movable from a retracted position clear of the rods 43 of the conveyor 25 into an operative position in engagement with the rods 43 in the upper reach 25a of the conveyor for rotating them as they move forward in the upper reach of the conveyor. As shown, this means comprises a pair of rails 145 mounted for up and down movement below the upper reach 25a of the conveyor adjacent its sides, and means for moving these rails up into its operative position in contact with the bare ends 53 of the rods 43 for rotating them, and down to a retracted position out of contact with the rods. The rails 145 are pinned on the upper ends of rocker arms 147 on three horizontal rock shafts 149 extending transversely across the apparatus between bars 57. The intermediate one of these rock shafts has a handle 151 for turning it to raise and lower the rails 145. Any suitable means may be provided to hold the rails raised. As shown in FIG. 5, the handle may overcenter against a stop 153 for this purpose. The rails 145 are raised to rotate the rods 43 when articles wrapped in a plastic (e.g., polyvinyl chloride) which may otherwise tend to become blemished on account of the rods being conveyed through the tunnel. For a plastic such as polyethylene, however, which tends to stick to the rods, the rails are left down for non-rotation of the rods to avoid having the polyethylene wind up on a rod.

Means indicated generally at 155 (see FIGS. 5, 8 and 10) may be provided just outside the exit end of the tunnel for pressing against the sides of the enwrapped article A leaving the tunnel. This means comprises a pair of vertical presser rolls each designated 157 on opposite sides of the longitudinal central plane of conveyor 25. Each roll is mounted on an arm 159 extending radially from the upper end of a vertical shaft 161 rotatable in a bracket 163 adjustable laterally of the conveyor supporting framework. The shaft is biased by a torsion spring 165 to swing the arm 159 to a position extending laterally inward from the shaft, determined by engagement ofa lug 167 on the shaft with a stop 169 on the bracket 163. The arrangement is such that an enwrapped article exiting from the tunnel engages the rolls 157, swings them forward and outward against the bias of springs 165, and then passes between the rolls which are pressed against the sides of the article by the springs. These spring-biased rolls smooth out the seals made along the sides of the wrapper including the flaps or folds made at the corners of the article thus resulting in an attractive wrapping.

In the operation of the apparatus for carrying out the method of FIGS. 1-4, generally the butterfly valves 129 in the ducts 85 at station S1 are opened wide and the shutters 135 at station S1 are closed to block the openings 133 at station S1 (see FIG. 6). The butterfly valves 129 in the ducts 123 at station S2 are closed, and shutters 135 at station S2 are opened for exit of air from these ducts via

openings

133 and 137 at station S2 (see FIG. 8). Thus, with the blower 91 in operation, hot air is delivered down through the ducts 85, exits through the openings 89 at the lower ends of the ducts, blows laterally inwardly over the tunnel bottom 65 from the sides of the tunnel underneath the upper reach 25a of conveyor 25, and finally is deflected upwardly on opposite sides of the-longitudinal central plane of the conveyor through the spaces 45 between the conveyor rods 43 by the curved ends of the deflectors 103 (see FIG. 6). These deflectors are laterally adjusted by turning the screw member 109 in accordance with the dimension of the article or work A between its side faces 1 so that the hot air blows upwardly on opposite sides of the work A as it travels through station S1 to fold the flaps l9 upwardly as shown in FIG. 3. In this regard, it will be understood that an item of work A enwrapped in wrapper 9 as shown in FIG. 1 is placed on the upper reach 25a of conveyor 25 at the entrance end of the tunnel T with sides 1 of the work and end portions 11 of the wrapper toward the sides of the conveyor and with the work generally centered widthwise of the upper reach of the conveyor, for being conveyed through the tunnel by the upper reach of the conveyor.

Thus, as the enwrapped work travels through station S1,.flaps 19 are folded upwardly as in FIG. 3 by the hot air caused to flow upwardly by the deflectors 103. Then as the enwrapped work passes beyond station S1 and travels through station S2, the flaps 21 are blown downwardly as shown in FIG. 4 by the hot air exiting from ducts 123 via

openings

133 and 137 and being deflected downwardly by the flanges 143 of the shutters at station S2. This completes the operation of closing and sealing the end portions of the wrapper 9 (as in FIG. 4), and the work then exits from the tunnel. Rolls 157, when used, press against the sides to augment the sealing together of the

flaps

21 and 19. They are not absolutely necessary. Rails may be raised to cause the rods 43 to rotate when needed, as above mentioned.

The entire wrapper 9 is heated by hot air in the tunnel T as the work passes through the tunnel, thus effecting shrinking of the wrapper. The tunnel T may be used for conventional shrink operations, when so desired, by closing or partly closing the valves 129 at station S1 and opening or partly opening the shutters 135 at station S1 so as to provide (in conjunction with the setting of valves 129 and shutters 135 at station S2) a suitable hot air distribution for shrink purposes only.

FIGS. 11-19 illustrate a second embodiment of the method of this invention which is particularly adapted for the use of relatively limp heat-scalable, heatshrinkable plastic film. An article constituting the work to be packaged is again indicated at A. Its ends are again designated 1, its front and rear sides are again each designated 3, and its top and bottom are again designated 5 and 7, respectively. As shown in FIG. 11, the article A is enwrapped in a wrapper 209 in the form of a tube or sleeve around the article. This tube or sleeve 209 has end portions each generally indicated at 211 extending beyond the opposite ends 1 of the article. It comprises a top sheet 213 of film overlying the top 5 of thearticle and having side portions folded down upon the front and rear sides 3 of the article, and a bottom sheet 215 of film underlying the bottom 7 of the article. The top sheet is severed from a web of film of greater width than the dimension of article A between its ends 1 (so as to provide extending end por-. tions of the sheet) and is of such length that the side portions, which are designated 216, extend down to the bottom of the work. The bottom sheet 215 is severed from a web of film also of greater width than the stated dimension of the article, but less than the width of the web from which the top sheet is severed, with its severed length such as to correspond generally to the dimension of article A between its front and rear faces 3. The lower edges of the side portions of the top sheet 213 and the front and rear side edges of the bottom sheet 215 are joined together by heat-sealed seams as indicated at 217 at the bottom of the article. The article A may be enwrapped in the

sheets

213 and 215 by means of the aforesaid SLEEVEMASTER machine.

As shown in FIGS. 11 and 12, the bottom sheet 215 is wider than the article A and the top sheet 213 is wider than the bottom sheet so that both sheets extend out beyond the ends 1 of the article and the top sheet, including its folded-down side portions 216, extends out beyond the ends of the bottom sheet. It will be observed that the bottom sheet is flat. As illustrated, and by way of example only, the top sheet extends out beyond the ends 1 of the article a distance approximating the height of the article, and the bottom sheet extends out beyond the ends of the article a distance equal to somewhat more than half the height of the article.

With the

sheets

213 and 215 of relatively limp plastic, the top parts 221 of the end portions of the top sheet 213 inherently drape themselves or fold downwardly around the top end edges of the article A and overlie the ends 1 of the article, as shown in FIGS. 14 and 15. This downfolding of the end top parts 221 of the top sheet results in the formation of flaps (shown ideally as triangular flaps) extending generally in endwise direction in relation to the tube 209 outwardly from the four vertical corners of the article. The two of these corner flaps disposed at the front side of the article are each designated 223, the other two are each designated 225. The corner flaps are joined to the extending parts of the bottom sheet, these extending parts being designated 227.

In accordance with this invention, both of the flaps 223 are folded back on the. respective vertical corner edges of the article A to overlie the downfolded top parts 221, as shown in FIGS. 16 and 17. The flaps 225 are folded so that in part they extend out from the respective side 3 of the article. Then, hot air is blown upwardly as indicated by the arrows in FIGS. 17 and 19 against the bottom of the extending bottom sections 227 to fold these up as outer flaps and to heat them and press them against the outside of parts 221 and flaps 223 (constituting inner flaps), thereby causing outer flaps 227 to become interfaciallyheat-sealed to flaps 223 and parts 221. The heat effects shrinking of the film, and the flaps 225 shrink to a condition as indicated at 229 in FIG. 18.

The method of FIGS. 11-19 is readily carried out via the apparatus of FIGS. -10. An article A with the wrapper 209 thereon is placed on the upper reach a of the conveyor 25 for travel through the shrink tunnel T with sheet 215 on the bottom and the wrapper extending crosswise of the conveyor so that its open ends are directed laterally toward the tunnel sides. Wrapper parts 221 fold or drape themselves down as shown with the consequent formation of the corner flaps 223 and 22 5. The work travels in the direction of the arrows shown in FIGS. 14 and 16, and the curtain 71 at the entrance end'of the tunnel T causes the

flaps

223 and 225 to fold back as illustrated in FIGS. 16 and 17. Then the outer flaps 227 are blown upwardly at station S1 by the hot air directed to flow upwardly by the deflectors 103. Hot air entering at station S2 is utilized in this instance only for providing good circulation of hot air in the tunnel for film shrinking purposes.

FIGS. 2024 illustrate a third embodiment of the method of this invention for packaging an article B (see FIG. 20) generally similar to article A in a wrapper 231 of heat-sealable, heat-shrinkable plastic, this wrapper differing from the wrapper 9 heretofore described. Article B is illustrated as box-like having front and

rear ends

233 and 235, respectively, a top 237, a bottom 239, and first and

second sides

241 and 243. As shown in FIG. 21, wrapper 231 comprises a bottom sheet 245 and a cover 247, each of heat-sealable, heat-shrinkable plastic film. The bottom sheet is larger than the article and underlies the article with its marginal portions extending beyond the ends and sides of the article. The cover is in the form of a bag placed on the article in inverted position covering top 237 of the article and extending down the sides and ends of the article. The marginal portions of the bottom sheet extending beyond the ends and sides of the article constitute flaps adapted to be folded up along the respective sides and ends of the article, to be pressed against the sides of the cover, and to be heat-sealed thereto to seal article B within wrapper 231. The flaps adjacent the front, rear and first and second sides of article B are respectively indicated at 249, 251, 253 and 255, and the sides of the cover adjacent the above-mentioned ends and sides of the article are respectively indicated at 257, 259, 261 and 263.

In accordance with the third embodiment of the method of this invention, heated air (as indicated by the arrows in FIGS. 22-24) is first blown upwardly on the front flap 249 to fold it upwardly on the front side 233 of the article, to press it against the front side 257 of cover 247, to heat it and to heat-seal it thereto (see FIG. 22). Hot air is then blown upwardly on the side flaps 253 and 255 to progressively fold them from front to rear on the

sides

241 and 243 of the article, to heat them, to press them against the

sides

261 and 263 of the cover and to heat-seal them thereto (see FIG. 23). Rear flap 25-1 is then blown upwardly and folded against the rear side 235 of the article and similarly heat-sealed to the rear side 259 of the cover thus sealing the article within wrapper 231. As the front'and

rear flaps

249 and 251 are folded up on their respective front and

rear sides

257 and 259 of cover 247, corner flaps or folds (as indicated by the diagonal line at the forwardmost corner of said flap 253in FIGS. 23 and 24) are formed. As the upwardly directed stream of heated air is directed against these corner flaps, the front corner flaps are folded against side flaps 253 and 255 and the rear corner flaps are folded against rear flap 251. It will be understood that the shape and location of the flaps may vary from article to article. The heated air blown upwardly against the bottom sheet to fold and heat-seal the flaps to the cover and the corner flaps to the side and rear flaps at least partially effects heating of the wrapper for heat-shrinking purposes. All the above operations are eflected in simple and expeditious manner by moving the work Bin bag 247 on sheet 245 in the direction indicated by the arrows in FIGS. 21-24 over an air outlet 265 directed to blow hot air upward across the width of sheet 245. Other heated air may then be blown against the wrapper to complete heating of the wrapper for heat-shrinking.

FIGS. 2527 illustrate apparatus made in accordance with this invention for carrying out the third embodiment of the method of this invention as illustrated in FIGS. 20-24. This modified apparatus is generally similar to the apparatus of FIGS. -10 and corresponding reference numerals indicate corresponding parts. At a first or heat-sealing station, designated Sla to distinguish it from station S1 of the apparatus of FIGS. 5-10, along the path of conveyor 25, means indicated generally at 265 is provided for blowing heated air upwardly against

flaps

249, 251, 253 and 255 of the bottom sheet 245 to fold these flaps upwardly against a

respective side

257, 259, 261 or 263 of cover 247, and also to heat these flaps and to press them against the sides of the cover to heat-seal them thereto (see FIGS. 22-24). Means indicated generally at 267 is provided at a second station S2a farther along the path of the conveyor for blowing heated air against wrapper 231 to heat it for effecting heat-shrinking of the wrapper.

The means 265 for blowing heated air upwardly at station Sla comprises a pair of vertical hot air ducts at opposite sides of tunnel T, each designated 269, adjacent the entrance end of the tunnel. These ducts are generally similar to ducts 85 of the apparatus of FIGS. 5-10. Each duct 269 is in communication at its upper end with a heater manifold 271 mounted on bottom wall 79 of plenum chamber 83. A centrifugal blower 273 is mounted within the plenum chamber with its inlet in communication via an opening 275 in panel 79 with the interior of the tunnel. The outlet 277 of blower 273 is connected to manifold 271. Heaters 279are provided in the heater manifold for heating the air, these heaters being similar to heaters 97. The heated air flows toward the ends of the manifold for entry into ducts 269. Blower 273 is driven by a motor 281 mounted outside the plenum chamber. An outlet manifold indicated at 283 is mounted on bottom wall 65 of the tunnel below upper reach 25a of conveyor 25 with its ends in communication with ducts 269, and has an upwardly facing outlet 285. As shown in FIG. 26, outlet 285 extends transversely of the upper reach 25a of the conveyor for blowing hot air upwardly against the bottom sheet 245 of the enwrapped work moving past station Sla on the conveyor. The spaced apart rollers 47 of the conveyor permit the heated air to impinge against bottom sheet 245 as it moves over outlet opening 285.

The means 267 for blowing heated air into the tunnel at station 52a comprises a pair of ducts, each indicated at 287, and extending vertically on the walls of the tunnel at opposite sides thereof farther along the path of the conveyor from station Sla, these ducts being generally similar to ducts 29 heretofore described. Ducts 287 are in communication with a heater manifold 289 in plenum chamber 83. A centrifugal blower 291 mounted'within the plenum chamber is driven by a motor 293, the blower having its inlet in communication with the interior of the tunnel via an opening 295 in panel 79, and has its outlet 297 in communication with manifold 289. Heaters 299 are provided in the heater manifold for heating the air. A series of openings 301 are provided in each tunnel side wall 73 in communication with a respective duct 287 to permit the outflow of heated air from the duct into the tunnel at station S2a. These discharge openings 301 are generally similar to discharge openings 133 heretofore described and it will be understood that shutters 135 (not shown in FIGS. 24-27) may be provided for controlling the flow of air through the openings 301 at station 52a if so desired. An enlarged opening 303 is provided in wall 73 at the bottom end of each duct 287 to discharge heated air into the tunnel below upper reach 25a of the conveyor. The heated air discharged from these ducts is blown against the top, sides, ends and bottom of the enwrapped article to heat the wrapper for heatshrinking purposes.

The method of FIGS. 20-24 is readily carried out via the apparatus of FIGS. 25-27. A bottom sheet 245 is first placed on the upper reach 25a of conveyor 25, an article B is .-n placed on the bottom sheet with

flaps

249, 251, 253 and 255 extending beyond the ends and sides of the article (see FIG. 20), and a cover or bag 247 is placed over the article (see FIG. 21). The enwrapped article travels continuously in the direction of the arrows as shown in FIG. 25 (and FIGS. 21-24), and the curtain 71 at the entrance end of tunnel T is pushed out of the way by the article permitting entry thereof into the tunnel. As the front flap 249 passes over air outlet 285 at station Sla, heated air discharged upwardly from the outlet blows against the front flap, folds it upwardly against the front side 233 of the article, heats it and presses it against the front side 257 of cover 247 to cause it to become heat-sealed thereto. Upon continuing movement of the conveyor, portions of the side flaps 253 and 255 adjacent the front flap encounter the upwardly directed curtain of heated air discharged from outlet 285 causing the forward portions of the side flaps to be folded up along

sides

241 and 243 of the article (the folds at the corners of the article ideally being triangular folds). The side flaps are progressively folded up along the sides of the article from front to rear as the article continues to move over outlet 285. These side flaps are heated and pressed against the

sides

261 and 263, respectively, by the heated air to cause them to become heat-sealed thereto. As the rearflap 251 passes over outlet 285, it also is folded up along the rear side 235 of the article and heat-sealed to the rear side 259 of the cover (again triangular folds being ideally formed between the side and back flaps). The heated air from duct 285 at least partially heats wrapper 235 for heat-shrinking purposes. As the conveyor moves the enwrapped and sealed article past sta-' tion S2a, heated air discharged from

openings

301 and 303 in ducts 287 heats the wrapper for completion of heat-shrinking. The article then exits from the tunnel and its side flaps are pressed against the sides of the article by rollers 157 to smooth out any wrinkles inthe I sides of the wrapper.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. The method of packaging one or more articles constituting the work to be packaged comprising wrapping the work in heat-scalable plastic film with part of the film constituting an outer flap adapted to be folded over upon the outside of and heat-sealed to another part of the film to close the wrapping, and blowing hot air against said outer flap in a direction such as to fold it over upon said other part of the film and also to heat it and press it against said other part of the film to cause it to become heat-sealed thereto.

2. The method of claim 1 wherein the film is a heatshrinkable plastic film and is heated at least in part by said directional air for effecting shrinking thereof on the work.

3. The method of claim 1 wherein the film has at least one open end portion extending beyond one surface of the work, and wherein a part of said end portion of the film is folded over toward said surface of the work to constitute an inner flap, the outer flap being blown by said hot air to overlap said inner flap and to become heat-sealed thereto.

4. The method of claim 3 wherein the work is wrapped in the heat-scalable plastic film with the film in the form of a tube around the article and with end portions of the tube extending beyond opposite ends of the work, a part of each said end portion of the tube being'folded over toward the respective end of the work to constitute inner flaps at each end of the work, and another part of each said end portion of the tube constituting an outer flap, and wherein hot air is blown against each of said outer flaps at each end of the work in such direction as to fold each outer flap over upon the respective inner flap and also to heat it and press it against the respective inner flap to cause it to become heat-sealed thereto.

5. The method of claim 4 wherein heated air is first blown against the parts of said end portions of the tube constituting the inner flaps in a direction such as to fold them against the ends of the work and to heat them for heatsealing, and wherein heated air is subsequently blown against the parts of said end portions of the tube constituting the outer flaps in a direction such as to fold them to overlap the inner flaps.

6. The method of claim 5 wherein the film is a heatshrinkable plastic film and is heated by said air for effecting shrinking thereof on the work.

7. The method of claim 6 wherein heated air is first blown upward against the bottom of the end portions of said tube to fold bottom sections of said end portions up against the said ends of the work and to hold top sections of said end portions of said tube in an extended position preventing said top sections from contacting said bottom sections, and wherein heated air is subsequently blown inwardly and downwardly on said top sections to fold them down to overlap said bottom sections, and also to heat and to press said top and bottom' sections together for effecting heat-sealing thereof.

8. The method of claim 7 wherein the said top and bottom sections extending beyond the opposite ends of the work are of different lengths.

9. The method of claim 8 wherein the tube of said film is formed from a top sheet and a bottom sheet of different widths with the top sheet wider than the bottom sheet so that said top sections extend beyond the. ends of said bottom sections, said top and bottom sheets being sealed together at the front and rear of the work to form said tube.

10. The method of claim 4 wherein, with the tube in generally horizontal position, the top parts of its said end portions fold down on the ends of the work, with consequent formation of flaps extending generally in endwise direction in relation to the tube outwardly from the four vertical corners of the work, and wherein two of these corner flaps disposed at one side of the work are folded back to overlie said downfolded top parts, and wherein hot air is blown upwardly against the bottom of the said end portions of the tube to fold bottom sections of said end portions upwardly as the said outer flaps and to cause them to become heat-sealed to said folded-back corner flaps.

11. The method of claim 10 wherein the film is a heat-shrinkable plastic film and is heated by said air for effecting shrinking thereof on the work.

12. The method of claim 11 wherein the tube is formed from a top sheet and a bottom sheet, the top sheet having side portions folded down on two opposite sides of the work and extending down to the bottom of the work and being heat-sealed at their lower edges to the side edges of the bottom sheet at the bottom of the work, both the top sheet and the bottom sheet extending beyond the work at both ends thereof and the top sheet extending beyond the bottom sheet at both ends thereof.

13. The method of claim 1 wherein the work is wrapped in film by placing a cover of the film on the work over the top of the work and extending down toward the bottom of the work and by applying the work to a bottom sheet of film with the sheet larger than the work to provide the said outer flap, the heated air being blown upwardly on said flap to fold it upwardly on the outside of the cover and to heat-seal it thereto.

14. The method of claim 13 wherein the cover and the bottom sheet are of heat'shrinkable plastic film and are heated at least in part by said directional air for effecting shrinking thereof on the work.

15. The method of claim 13 wherein said cover is a bag placed in inverted position over the work.

16. The method of claim 15 wherein said bottom sheet has marginal portions constituting flaps extending beyond the ends and sides of the work, and wherein hot air is blown against each of said flaps in such direction as to fold it up and over upon the respective 'end or side of the bag and also to heat it and to press it against its respective side of the bag to cause it to become heatsealed thereto.

17. The method of. claim 15 wherein said bottom sheet has marginal portions constituting flaps extending beyond the ends and sides of the work, and wherein hot air is first blown upwardly against. one of the flaps at one end of the work constituting its front end to fold it up and over upon the front end of the bag, heated air is then blown upwardly against the flaps at the sides of the work from the front end of the work to its other end constituting its rear end, progressively to fold up the side flaps against the sides of the bag, and then heated air is blown upwardly against the flap at the rear end of the work to fold it up against the rear end of the bag, said front, side and rear flaps being heated and pressed against respective sides of said bag by said directional air to cause the flaps to become heat-sealed thereto.

18. The method of claim 17 wherein the work is moved past a heat-sealing station at which heated air is blown upwardly against the said fllaps of said bottom sheet first to fold upwardly the front flap against the front end of the bag, then blown upwardly against the side flaps from the front to the rear end of the work progressively to fold up the side flaps against the sides of the bag as the work moves past the heat-sealing station, and then blown upwardly against the rear flap to fold it up against the rear end of the bag as it moves past the heat-sealing station.

19. The method of claim 18 wherein the bag and the bottom sheet are heated by said hot air at least in part for effecting shrinking thereof on the work.

20. Apparatus for packaging one or more articles constituting the work to be packaged in heat-scalable, heat-shrinkable plastic film comprising means for conveying an item of work along a predetermined path with the work enwrapped in heat-scalable, heatshrinkable plastic film with part of the film constituting an outer flap adapted to be folded over upon and heatsealed to another part of the film to close the wrapper, means for heating air to a temperature sufficient to effect heat-sealing of said plastic-film, and means located along said path for blowing the heated air against said outer flap in a direction for folding it over upon said other part of the film and for heating it and for pressing it against said other part of the film to cause it to become heat-sealed thereto.

21. Apparatus as set forth in claim 20 comprising a shrink tunnel, said conveying means comprising an endless conveyor having an upper reach extending through the tunnel from one end thereof constituting its entrance end to its other end constituting its exit end for conveying an item of work through the tunnel, said work being enwrapped in a heat-sealable, heatshrinkable plastic film wrapper in the form of a tube with end portions of the tube extending beyond the'respective ends of the work, and said means for blowing heated air being structured and positioned to blow heated air upwardly in the tunnel at opposite ends of the work to blow sections of said end portions of the tube upwardly for folding and pressing them against other portions of the plastic film'and to heat them for heat-sealing thereof.

22. Apparatus as set forth in claim 21 wherein the conveyor has openings for passage of air, and wherein said blowing means blows the air laterally inwardly from the sides of the tunnel underneath the upper reach of the conveyor, and includes deflectors below said upper reach for deflecting the air upwardly through said upper reach.

23. Apparatus as set forth in claim 22 wherein the deflectors are movable toward and away from one another, and wherein means is provided for moving them toward and away from one another.

24. Apparatus as set forth in claim 22 wherein the conveyor comprises a pair of endless chains and rods extending transversely between the chains, each rod being rotatable on its axis, and having means for preventing blemishing of the wrapper by the rods as the enwrapped article is conveyed through the tunnel, this last-said means including means movable from a retracted position clear of the rods into 'a position in engagement with the rods in the upper reach of the conveyor for rotating them as they move forward in the upper reach of the conveyor thereby to effect relative movement between said wrapper and said rods.

25. Apparatus as set forth in claim 24 wherein said means for rotating the rods comprises a pair of rails mounted for up and down movement below the upper reach of the conveyor adjacent its sides, and means for moving said rails up into an operative position in contact with the ends of the rods for rotating them and down to a retracted position out of contact with the rods.

26. Apparatus as set forth in claim 21 wherein said means for blowing heated air is further structured and positioned at a second station along the tunnel for blowing the air laterally inwardly and downwardly from the upper portions of opposite sides of the tunnel, and further comprises a plenum chamber at the top of the tunnel, air ducts extending downwardly from said chamber at said second station at opposite sides of the tunnel, and a blower and a heater for supplying heated air to said chamber and thence to said ducts, said ducts having openings for delivery of air to the tunnel at the upper part of its sides, and having means for deflecting downwardly the air entering the tunnel via these openings, said means for deflecting the air downwardly also being movable for regulating the flow of air from said openings.

27. Apparatus as set forh in claim 20 comprising a shrink tunnel, said conveying means extending through the tunnel from one end thereof constituting its entrance end to its other end constituting its exit end for conveying an item of work enwrapped in said film through the tunnel, said wrapping comprising a cover applied to the tap of the work extending down the ends and sides of the work and a bottom sheet under the work larger than the work, said sheet having marginal portions extending beyond the ends and sides of the work with each of said marginal portions constituting a flap, and said means for blowing heated air being located at a first station along said path for blowing hot air upwardly to fold said flaps up on the ends and sides of the work and to heat them and press them against the sides of the cover at the respective end or side of the work to cause them to become heat-sealed thereto.

28. Apparatus as set forth in claim 27 wherein said conveying means is an endless conveyor having an upper reach movable through the tunnel for conveying an item of work therethrough, said conveyor comprising a pair of endless chains and rods extending transversely between the chains, each rod being rotatable on its axis and being spaced apart from adjacent rods for the passage of heated air therethrough, and means for preventing blemishing of the wrapper by the rods as the enwrapped article is conveyed through the tunnel, this last-said means including means movable from a retracted position clear of the rods into position in engagement with the rods in the upper reach of the conveyor for rotating them as they move forward in the upper reach of the conveyor thereby to effect relative movement between said wrapper and said rods.

29. Apparatus as set forth in claim 28 wherein said means for rotating the rods comprises a pair of rails mounted for up and down movement below the upper reach of the conveyor adjacent its sides, and means for moving said rails up into an operative position in contact with the ends of the rods for rotating them and down to a retracted position out of contact with the rods.

30. Apparatus as set forth in claim 27 having a second means for blowing heated air at a second station along the tunnel for heating the wrapper for heatshrinking purposes.

31. Apparatus as set forth in claim 30 wherein said conveying means is an endless conveyor having openings for passage of air therethrough, said conveyor having an upper reach movable through the tunnel for con veying an item of work therethrough, and wherein the first means for blowing heated air at said first station comprises an outlet located in said tunnel below said upper reach for directing heated air upwardly thereby to fold said flaps upwardly on the ends and sides of the work and to heat-seal them to the sides of the cover, and a blower and heater for supplying heated air to the outlet.

32. Apparatus as set forth in claim 30 wherein the means at the second station for blowing heated air comprises air ducts extending vertically along the sides of the tunnel at opposite sides thereof, with openings from these ducts for delivery of heated air to the tunnel, and a blower and heater for supplying heated air to the ducts.

33. Apparatus as set forth in claim 31 wherein said outlet extends transversely of the upper reach substantially from one side thereof to the other first to fold up the front flap as the front end of the work travels over the outlet, then to progressively fold up each side flap from the front end to the rear end of the work as the work travels over the outlet, and then to fold up the rear flap of the work as the rear end of the work travels over the outlet.

34. Packaging apparatus comprising a shrink tunnel and an endless conveyor having an upper reach extending through the tunnel for conveying work through the tunnel, said conveyor comprising a pair of endless chains and rods extending transversely between the chains, each rod being rotatable on its axis, and having means for preventing blemishing of the wrapper by the rods as the enwrapped article is conveyed through the tunnel, this last-said means including means movable from a retracted position clear of the rods into a position in engagement with the rods in the upper reach of the conveyor for rotating them as they move forward in the upper reach of the conveyor thereby to effect relative movement between said wrapper and said rods.

35. Packaging apparatus as set forth in claim 34 wherein said means for rotating the rods comprises a pair of rails mounted for up and down movement below the upper reach of the conveyor adjacent its sides, and means for moving said rails up into an operative position in contact with the ends of the rods for rotating them and down to a retracted position out of contact with the rods.

36. Packaging apparatus as set forth in claim 35 wherein the rails are carried by rocker arms on a plurality of rock shafts extending transversely of the conveyor.

37. Apparatus for packaging one or more articles constituting the work to be packaged in heat-sealable, heat-shrinkable plastic film, comprising a shrink tunnel, means for conveying an item of Work along a predetermined path through the tunnel with the work enwrapped in heat-scalable, heat-shrinkable plastic film and with part of the film constituting a flap extending outwardly beyond one end of the work at the bottom thereof adapted to be folded up over upon said end of the work, and means located along said path for blowing heated air upwardly against said flap in a direction for folding it up over upon said end of the work.

38. Apparatus as set forth in claim 37 wherein said conveying means comprises an endless conveyor having an upper reach extending through the tunnel from one end thereof constituting its entrance end to its other end constituting its exit end for conveying an item of work through the tunnel, said work being enwrapped in a heat-sealable, heat-shrinkable plastic film wrapper in the form of a tube with end portions of the tube extending beyond the respective ends of the work, and said means for blowing heated air being structured and positioned to blow heated air upwardly in the tunnel at opposite ends of the work to blow sections of said end portions of the tube upwardly.

39. Apparatus as set forth in claim 38 wherein the conveyor has openings for passage of air, and wherein said blowing means blows the air laterally inwardly from the sides of the tunnel underneath the upper reach of the conveyor, and includes deflectors below said upper reach for deflecting the air upwardly through said upper reach.

40. The method of packaging one or more articles constituting the work to be packaged in heat-scalable plastic film comprising wrapping the work in heatsealable plastic film with a part of "the film constituting a flap extending outwardly beyone one end of the work at the bottom end thereof to be folded up over upon said one end of the work, and blowing air heated to a temperature sufficient to effect heat-sealing of the film against said flap in a direction such as to fold it over upon said one end of the work and also to press it at least in part against another part of the film to cause it to become heat-sealed thereto.

41. The method of claim 40 wherein said step of blowing heated air against said flap further comprises heating the end portions of said flap and pressing these end portions of the flap into engagement with other parts of the film so as to heat-seal the flap to said other parts of the film. I

Claims

1. The method of packaging one or more articles constituting the work to be packaged comprising wrapping the work in heat-sealable plastic film with part of the film constituting an outer flap adapted to be folded over upon the outside of and heat-sealed to another part of the film to close the wrapping, and blowing hot air against said outer flap in a direction such as to fold it over upon said other part of the film and also to heat it and press it against said other part of the film to cause it to become heat-sealed thereto.

2. The method of claim 1 wherein the film is a heat-shrinkable plastic film and is heated at least in part by said directional air for effecting shrinking thereof on the work.

4. The method of claim 3 wherein the work is wrapped in the heat-sealable plastic film with the film in the form of a tube around the article and with end portions of the tube extending beyond opposite ends of the work, a part of each said end portion of the tube being folded over toward the respective end of the work to constitute inner flaps at each end of the work, and another part of each said end portion of the tube constituting an outer flap, and wherein hot air is blown against each of said outer flaps at each end of the work in such direction as to fold each outer flap over upon the respective inner flap and also to heat it and press it against the respective inner flap to cause it to become heat-sealed thereto.

5. The method of claim 4 wherein heated air is first blown against the parts of said end portions of the tube constituting the inner flaps in a direction such as to fold them against the ends of the work and to heat them for heat-sealing, and wherein heated air is subsequently blown against the parts of said end portions of the tube constituting the outer flaps in a direction such as to fold them to overlap the inner flaps.

6. The method of claim 5 wherein the film is a heat-shrinkable plastic film and is heated by said air for effecting shrinking thereof on the work.

7. The method of claim 6 wherein heated air is first blown upward against the bottom of the end portions of said tube to fold bottom sections of said end portions up against the said ends of the work and to hold top sections of said end portions of said tube in an extended position preventing said top sections from contacting said bottom sections, and wherein heated air is subsequently blown inwardly and downwardly on said top sections to fold them down to overlap said bottom sections, and also to heat and to press said top and bottom sections together for effecting heat-sealing thereof.

9. The method of claim 8 wherein the tube of said film is formed from a top sheet and a bottom sheet of different widths with the top sheet wider than the bottom sheet so that said top sections extend beyond the ends of said bottom sections, said top and bottom sheets being sealed together at the front and rear of the work to form said tube.

14. The method of claim 13 wherein the cover and the bottom sheet are of heat-shrinkable plastic film and are heated at least in part by said directional air for effecting shrinking thereof on the work.

16. The method of claim 15 wherein said bottom sheet has marginal portions constituting flaps extending beyond the ends and sides of the work, and wherein hot air is blown against each of said flaps in such direction as to fold it up and over upon the respective end or side of the bag and also to heat it and to press it against its respective side of the bag to cause it to become heat-sealed thereto.

17. The method of claim 15 wherein said bottom sheet has marginal portions constituting flaps extending beyond the ends and sides of the work, and wherein hot air is first blown upwardly against one of the flaps at one end of the work constituting its front end to fold it up and over upon the front end of the bag, heated air is then blown upwardly against the flaps at the sides of the work from the front end of the work to its other end constituting its rear end, progressively to fold up the side flaps against the sides of the bag, and then heated air is blown upwardly against the flap at the rear end of the work to fold it up against the rear end of the bag, said front, side and rear flaps being heated and pressed against respective sides of said bag by said directional air to cause the flaps to become heat-sealed thereto.

18. The method of claim 17 wherein the work is moved past a heat-sealing station at which heated air is blown upwardly against the said flaps of said bottom sheet first to fold upwardly the front flap against the front end of the bag, then blown upwardly against the side flaps from the front to the rear end of the work progressively to fold up the side flaps against the sides of the bag as the work moves past the heat-sealing station, and then blown upwardly against the rear flap to fold it up against the rear end of the bag as it moves past the heat-sealing station.

20. Apparatus for packaging one or more articles constituting the work to be packaged in heat-sealable, heat-shrinkable plastic film comprising means for conveying an item of work along a predetermined path with the work enwrapped in heat-sealable, heat-shrinkable plastic film with part of the film constituting an outer flap adapted to be folded over upon and heat-sealed to another part of the film to close the wrapper, means for heating air to a temperature sufficient to effect heat-sealing of said plastic film, and means located along said path for blowing the heated air against said outer flap in a direction for folding it over upon said other part of the film and for heating it and for pressing it against said other part of the film to cause it to become heat-sealed thereto.

21. Apparatus as set forth in claim 20 comprising a shrink tunnel, said conveying means comprising an endless conveyor having an upper reach extending through the tunnel from one end thereof constituting its entrance end to its other end constituting its exit end for conveying an item of work through the tunnel, said work being enwrapped in a heat-sealable, heat-shrinkable plastic film wrapper in the form of a tube with end portions of the tube extending beyond the respective ends of the work, and said means for blowing heated air being structured and positioned to blow heated air upwardly in the tunnel at opposite ends of the work to blow sections of said end portions of the tube upwardly for folding and pressing them against other portions of the plastic film and to heat them for heat-sealing thereof.

24. Apparatus as set forth in claim 22 wherein the conveyor comprises a pair of endless chains and rods extending transversely between the chains, each rod being rotatable on its axis, and having means for preventing blemishing of the wrapper by the rods as the enwrapped article is conveyed through the tunnel, this last-said means including means movable from a retracted position clear of the rods into a position in engagement with the rods in the upper reach of the conveyor for rotating them as they move forward in the upper reach of the conveyor thereby to effect relative movement between said wrapper and said rods.

27. Apparatus as set forh in claim 20 comprising a shrink tunnel, said conveying means extending through the tunnel from one end thereof constituting its entrance end to its other end constituting its exit end for conveying an item of work enwrapped in said film through the tunnel, said wrapping comprising a cover applied to the top of the work extending down the ends and sides of the work and a bottom sheet under the work larger than the work, said sheet having marginal portions extending beyond the ends and sides of the work with each of said marginal portions constituting a flap, and said means for blowing heated air being located at a first station along said path for blowing hot air upwardly to fold said flaps up on the ends and sides of the work and to heat them and press them against the sides of the cover at the respective end or side of the work to cause them to become heat-sealed thereto.

30. Apparatus as set forth in claim 27 having a second means for blowing heated air at a second station along the tunnel for heating the wrapper for heat-shrinking purposes.

31. Apparatus as set forth in claim 30 wherein said conveying means is an endless conveyor having openings for passage of air therethrough, said conveyor having an upper reach movable through the tunnel for conveying an item of work therethrough, and wherein the first means for blowing heated air at said first station comprises an outlet located in said tunnel below said upper reach for directing heated air upwardly thereby to fold said flaps upwardly on the ends and sides of the work and to heat-seal them to the sides of the cover, and a blower and heater for supplying heated air to the outlet.

37. Apparatus for packaging one or more articles constituting the work to be packaged in heat-sealable, heat-shrinkable plastic film, comprising a shrink tunnel, means for conveying an item of work along a predetermined path through the tunnel with the work enwrapped in heat-sealable, heat-shrinkable plastic film and with part of the film constituting a flap extending outwardly beyond one end of the work at the bottom thereof adapted to be folded up over upon said end of the work, and means located along said path for blowing heated air upwardly against said flap in a direction for folding it up over upon said end of the work.

40. The method of packaging one or more articles constituting the work to be packaged in heat-sealable plastic film comprising wrapping the work in heat-sealable plastic film with a part of the film constituting a flap extending outwardly beyond one end of the work at the bottom end thereof to be folded up over upon said one end of the work, and blowing air heated to a temperature sufficient to effect heat-sealing of the film against said flap in a direction such as to fold it over upon said one end of the work and also to press it at least in part against another part of the film to cause it to become heat-sealed thereto.

41. The method of claim 40 wherein said step of blowing heated air against said flap further comprises heating the end portions of said flap and pressing these end portions of the flap into engagement with other parts of the film so as to heat-seal the flap to said other parts of the film.