US3866386A

US3866386A - Method and apparatus for making a shrink pack

Info

Publication number: US3866386A
Application number: US368527A
Authority: US
Inventors: Robert H Ganz
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-01-17
Filing date: 1973-06-11
Publication date: 1975-02-18
Anticipated expiration: 1992-02-18

Abstract

The invention contemplates use of heat-shrinkable plastic film for the packaging of clusters of containers, such as cylindrical beverage cans of a given size. One or more local reinforcing laminations, such as filaments beads or pleats are formed in the film prior to wrapping the containers, the location of such laminations being such as to form a tough handle region, for ready portability of the packaged cluster. The preformed nature of the lamination is to withstand such local film tensions as develop in the course of heat-shrinking to consolidate the packaged cluster. Various forms of lamination, and methods and means of making the same, are shown and described.

Description

[ 1 Feb. 18, 1975 Primary ExaminerRobert L. Spruill Attorney, Agent, or Firm-Sandoe, Hopgood and Calimafde [57] 7 ABSTRACT The invention contemplates use of heatshrinkable plastic film for the packaging of clusters of containers,

such as cylindrical beverage cans of a given size. One or more local reinforcing laminations, such as filaments beads or pleats are formed in the film prior to wrapping the containers, the location of such laminations being such as to form a tough handle region, for ready portability of the packaged cluster. The preformed nature of the lamination is to withstand such local film tensions as develop in the course of heatshrinking to consolidate the packaged cluster. Various forms of lamination, and methods and means of making the same, are shown and described.

METHOD AND APPARATUS FOR MAKING A SHRINK PACK Inventor: Robert H. Ganz, 8 Ridge Crest Rd., Saddle River, NJ. 07458 Filed: June 11, 1973 Appl. No; 368,527

Related U.S. Application Data Continuation-impart of Ser. No, 218.441, Jan. 1972, Pat. No. 3,756,395.

U.S. 53/14, 53/30, 53/128 Int. C1...B65b 11/10, B65b 53/02, B656 61/00 Field of Search 53/14, 30, 48, 128; 156/84, 85, 200, 204, 461, 465, 474; 206/65 S; 229/DIG. 12

References Cited UNITED STATES PATENTS United States Patent Ganz I M a a s H w W 5 m 1 Wu P... H mm We 5 M w Mm 7 1 m Mm 6 a Q, B .m M C H 156/474 X Rosen et al 229/87 B Buttery ct a1. 206/65 C LAM/MANN? PATENTED FEB I 81975 SHEET 10F 2 METHOD AND APPARATUS FOR MAKING A SHRINK PACK This application is a continuation-in-part of my copending application, Ser. No. 218,441, filed Jan. 17, 1972 now U.S. Pat. No. 3,756,395.

This invention relates to shrink-packaging of clusters of containers, such as cylindrical beverage cans of a given size. Specifically, the invention is concerned with improvements over the disclosure in my U.S. Letters Pat. No. 3,660,961 which issued on May 9, 1972, and it is also applicable to wrapping techniques beyond those described in said patent.

The development of shrink-packaging, especially the shrink-packaging of clusters of cylindrical beverage containers, for example, the popular 2 X 3 six pack of 12-02. cans, is extremely competitive, the primary aim being to produce at least cost, not only a sufficiently attractive display of the containers in a package that will withstand abusive handling, but also a package which will be readily portable with simple access for container removal from the cluster. lnevitably, cost of materials is the biggest factor, but portability suffers when the shrink-film material is of too-thin gauge.

It is, accordingly, an object of the invention to provide a method and apparatus for making an improved cluster package of the character indicated.

Another object is to provide such a method and apparatus to produce vastly superior portability for a shrink-wrap cluster package, using shrink-film of a gauge previously considered unacceptably thin.

A further object is to achieve the above objects without degrading overall ruggedness of the package and providing even easier access for container removal from the cluster.

It is also an object to achieve the above objects using existing wrapping machinery and methods, with a minimum of modifications and without affecting the efficiency or speed of wrapping.

A general overall object is to achieve major economies in unit-package cost while meeting the above objects, and without resort to inserted paperboard or the like reinforcements.

Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification, in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, preferred forms of the invention:

FIG. 1 is a simplified view in perspective of a shrinkwrapping production line to which my invention has been applied;

FIG. 2 is an enlarged perspective view of a 2 X 3 six-pack, being a product of the machine of FIG. 1;

FIG. 3 is a fragmentary view in perspective of a portion of the upper panel of the wrap of FIG. 2, taken at section line 33 thereof and with an exaggerated showing of certain wrap-material laminations;

FIG. 4 is a view similar to FIG. 3, to illustrate a modification;

FIG. 5 is a simplified view in perspective of laminating apparatus embodied in the machine of FIG. 1;

FIG. 6 is a view similar to FIG. 2 to show a modified cluster package;

FIG. 7 is a view similar to FIG. 3 but taken at the section line 7-7 of FIG. 6;

FIGS. 8 and 9 are views similar to FIGS. 3 and 7, to show a further modification;

FIG. 10 is a view similar to FIGS. 2 and 6, to show a still further modified cluster package;

FIG. 11 is a view similar to FIG. 3 but taken at the section line l1-l1 of FIG. 10;

FIG. 12 is a plan view of sheet material used in wrapping the package of FIG. 10;

FIG. 13 is a simplified view in perspective of modified laminating apparatus, usable in place of the apparatus of FIG. 5;

FIGS. 13A and 13B are sectional views across sheet material processed by the apparatus of FIG. 13, and taken at successive stages in the course of progression through said apparatus; and

FIG. 14 is a fragmentary view in perspective of further modified apparatus, as an alternative for some of the structure of FIG. 5.

The invention is shown in connection with a production-line machine (FIG. 1) for shrink-packaging a 2 X 3 six-pack (FIG. 2) of like cylindrical containers, such as 12-02. beverage cans. The machine operates continuously, using generally horizontal cluster-conveyor means running from left to right (in the sense of FIG. 1), as suggested byarrow designations, and also using a continuous elongated sheet or film of shrink-wrap material such as polyethylene having bi-axial shrink properties.

The machine of FIG. 1 may be essentially as described in detail in said U.S. Letters Pat. No. 3,660,961. It suffices for present purposes to explain that cluster-forming mechanism, as described in said patent, delivers 2 X 3 clusters to the conveyor, in regular short spacings between clusters. For purposes of simplified identification, successive clusters in FIG. 1 are marked A, B, C ..M, working back from the completely packaged cluster A, which is shown in larger detail in FIG. 2. The incoming unwrapped cluster M provides a convenient place to identify a typical cluster as comprising six like cylindrical containers 10-11-12-13-14-15, in closely nested array, with the longitudinal or three-container axis of the cluster oriented transverse to the longitudinal axis of conveyor movement. Shrink material 16, of width greater than the three-container dimensional extent of each cluster and continuously supplied from a reel 17, is fed over suitable guide and tension roll systems 18-19-20-21 to present a flat substantially horizontal top-panel region 22 over the cluster G. An endless overhead sheetguiding system 23 (having a lower span or course at substantially the plane of the upper ends of passing clusters E-F-G-I-I) is suspended by suitable sprocket means 24-25-26, with drive-synchronizing connection 27 to the drive 27 for the cluster-conveyor means, suggested at 28. The sheet-guiding system 23 determines the synchronized path of movement of the individual bars of a plurality of pairs, having articulated-arm connection to each other and at cluster-width spacings along the system 23. Each pair is typified by the bars 29-30 of the pair which is shown poised for downward entry into the space between clusters H-I; at this instant, the sheet material between guide roll 21 and the lower bar 29 slopes slightly above the horizontal, to clear all but the top front-corner edges of front containers in the next-succeeding cluster I. The two pairs 2930 and 29"30" which immediately precede the pair 29-30 are shown in successive, more-advanced stages of continuously wrapping clusters l-I-G-F, by drawing loops of sheet material down between (and part-way beneath successive clusters, prior to cut-off or severance by means such as a hot wire at 31.

Legends applied to clusters in the package-forming region explain successive functions, namely:

at cluster H, registration for pull, i.e., with the sheet material symmetrically projecting to overhang beyond both ends of the three-container dimensional extent of cluster H, as bar 29 is poised to enter between clusters I-l-l, and as bars 29'-30 are about to complete their loop-pulling function between clusters G-H; I

at cluster G, loop-pulling between clusters G-H and beneath cluster G;

at cluster F, severance, by means 31 at the fully pulled-out condition beneath cluster F;

at cluster E, air-blasted flattening (by means 32) of the back flap which is left hanging upon withdrawal of a loop-pulling pair of bars (not shown); at cluster D, conveyor-application of holding means 33 to retain the back flap flat against the bottom of cluster D; l

at cluster C, front-flap wrapping by a shuttle bar 34 (with horizontal motion suggested by a doubleheaded arrow), to lap the front flap beneath cluster C, in overlap with the back flap; and

at cluster B, simultaneous bonding of front and back flats, as well as shrinking, as a result of accelerated conveyor transport through a heat tunnel 35.

Preferably, cluster-transport through the heat tunnel provides a localized heat-shielding function (as by spaced longitudinally aligned container-support elements 36-37-38), so that in the region of flap overlap the heat-bonded region is not continuous but, rather, is at spaced locales along the overlap; as explained in Ganz application Ser. No. 29,127, filed Apr. 16, 1970, these bondedlocales occur at both ends of the overlap and in regions between longitudinal alignment of container centers, i.e., between the center alignment for the container pair -13 and the center alignment for the container pair 11-14, and between the center alignment for the container pair 11-14 and the center alignment for the container pair 12-15.

The completed article, cluster A, issues from the heat tunnel, being quickly cooled by room temperature, to a tight contour-conforming set of the shrink material, as shown. The shrink action collapses the overhung ends of wrapped material, to define a continuous band over both ends of the wrapped cluster, leaving end openings for direct access to a container.

The plan-view geometry of a 2 X 3 cluster is such that two spaced openings are defined at 39-40 (see cluster M), between adjacent interior convex surfaces rior convex surfaces of containers 11-12-14-15. These openings provide fingeraccess upon local puncture of the top panel of the shrunk material and, if the gauge of the material is sufficiently heavy, the package can be safely carried, using such access for hand-grip via the top panel. However, I consider it wasteful to use the heavier-gauge material if its weight is required essentially only to serve a safely portable function. Of course, paperboard or other insert stiffeners may be provided to permit use ofthin-gauge shrink material, as

.of containers 10-11-13-14, and between adjacent inte- In accordance with the invention, I achieve secure portability using relatively thin-gauge sheet material and without the need to rely on paperboard or other inserts in the cluster. I achieve this result by performing a local laminating operation on the continuously supplied sheet material 16, at suitable means 45 interposed between rolls 20-21 of the feed mechanism of FIG. 1. The laminating function is shown in FIG. 1 to develop two laminated reinforcement alignments 46-47, symmetrically offset from the longitudinal center of the sheet, preferably at a spacing D which is slightly less than a container diameter. In FIG. 2, this relationship is seen to produce a packaged cluster wherein the top panel 48 is characterized by parallel laminated reinforcement margins 49-50, just inside the locations 51-52 of finger access. The margins 49-50 positively resist any tendency to rip the top-panel material, no matter how tightly the fingers gras'p between access points 51-52, and substantially all lifting stresses are directly transmitted to regions remote from the fingeraccess points, thus broadly distributing lifting forces and allowing the substantial body of the shrink material to take the load.

The laminated regions 49-50 are seen in FIG. 3 to be integrally developed as opposed single pleats or folds, of individual width W,. Such folds may be longitudinally continuously bonded or consolidated as lamina tions to the adjacent sheet material, by localized application of the heat prior to introduction, at 21, to the described wrapping procedure; in such event, the regions 49-50 continuously ring the completed package, affording direct reinforcement to the undersides of the center container pair 11-14 of each cluster.

Alternatively, and as specifically shown in FIG. 2, the bonded extent. of laminations 49-50 is localized, longitudinally of sheet 16, so as to occur primarily at the upper panel region; between such localized bonded (laminated) regions, the slightly tensed even draw on pleated material, as at and beyond roller '21, assures wrapping (clusters H through C) without loss of pleats. A synchronizing connection 53 of the localizedbonding function with the described wrapping functions assures that the pleated region which is ultimately drawn across the tops of clusters (e.g., of cluster G, and of those which preceded it along the production line) is in fact the desired locally bonded region. That being the case, the unbonded remainder of the pleat formations is available for shrinking in the heat tunnel, thus producing a flared dissipation of the pleats in the downward direction of the front and back panels of the wrap. Such pleat dissipation is suggested at 54-55 for the pleats 49-50, down the panel 56.

It will be understood that essentially the same action and results are achieved for the alternative pleat arrangement of FIG. 4, wherein the sense of pleats 49-50 is merely reversed from that shown for FIG. 3.

The only noticeable difference is in appearance, and it may be considered that the appearance in FIG. 4 of a shown in said pending applications, but this too is an expensive resort.

single central, smoothly seamed band 57 is aesthetically more pleasant.

FIG. 5 is a simplified diagram to illustrate apparatus, contained at 45 in FIG. 1, for performing described laminating functions. Basically, such apparatus includes means '60 delivering incoming smooth sheet material 16 to a pleating head 61, thence to means 62 for locally bonding the pleated regions into locally consolidated laminations, and finally to an exit-guide roller 63.

As shown, the pleating head 61 comprises a central upper shoe or plate 64, fixed by upstanding struts 65 to a lower transverse frame member 66, and two lower shoes or plates 67-68, fixed by similar struts (as at 69, for plate 68) to an upper transverse frame member 70. The upstream ends of shoes 64-67-68 may be contoured for smooth pleat-shaping entry into oncoming sheet material 16. As shown, with the central shoe 64 spaced slightly above the remaining shoes 67-68, with an upper shoe of width D, and with a lower-shoe spacing of D-ZW the action will be to produce the pleat described for FIG. 4; and it will be understood that the pleat described for FIG. 3 is obtained by reversing the upper-to-lower relationship of shoe 64 with respect to shoes 67-68.

Heating local to the pleated regions bonds and consolidates the laminations, and as shown in FIG. 5, such consolidation is at longitudinally intermittent intervals, synchronized by means 53 to the basic wrapping cycle of means 23. To achieve such bonding at 62, I show the drums 71-72, one above the other below the pleated sheet, and driven in opposite directions. One of both of drums 71-72 may be heated (as suggested by legend), at least at the region of mating arcuate pairs of squeeze ridges 73-74, laterally spaced to register with pleats 46-47. The circumference of the circles, of outer contour and of rotation, of ridges 73-74, is selected to match the unshrunk wrapped longitudinal extent of each-severed length of sheet material, and the arcuate extent is selected to substantially match the desired cally bonded longitudinal extent at top panel 48. Preferably, the vertical separation of drum axes is selected to assure firm squeezing compression of the pleated regions 46-47, for efficient transmission of heat, at least for transient-tacking or bonding.

It has been indicated that finger-access points may be provided at regions 39-40 adjacent the laminations 49-50. This may be a conveniently performed additional function of the mating drums 71-72. Thus, pointed or sharp-edged piercing elements 75-76 carried by the lower drum 72, and symmetrically positioned in outward lateral offset from ridges 74, may project radially beyond ridges 74 (to an extent at least no greater than the radial offset of ridges 73 from drum 71). Elements 75-76 necessarily locally pierce the passing sheet material at regions designated 51-52 in FIG. 2, and preferably the piercing is crescent-shaped or arcuate, as shown, with the concave sides of the arcs facing outwardly. Such arcuate formations open slightly and are also slightly edge-beaded in passage through the heat tunnel, leaving convenient pull tabs 51-52 for outward ripping, to assist in container removal from the packaged cluster.

FIGS. 6 and 7 illustrate a modified package in which the pleat widths W at 77-78 are substantially one half the span D between reinforcement limits. FIG. 6 also shows continuously laminated bonded reinforcement, for the full peripheral extent of the package including the bottom and upstanding sides, as at 79.

FIG. 8 illustrates a further modification wherein separated pleated regions 81-82 are more widely spaced, to the extent D and are each of width W sufficient to embrace a pierced, punched or otherwise formed finger-access opening 83-84 within each pleated region, in registry with the respective internal spaces 39-40 between containers. It will be understood that apparatus as described in FIG. 5 may produce the configuration I, of FIG. 8, for a suitably selected dimensioning and orientation of shoes 64-67-68 and for a suitably positioned placement of the squeeze ridges 73-74, wherein coacting male and female punch or the like elements are provided centrally of the respective mating ridges 73-74.

FIG. 9 illustrates a still further modification wherein spaced sets of opposed pairs of pleats 85-86 are developed at substantially the spacing D already described, using spaced sets of narrower shoes 64-67-68. Each pleat width W, is as small as conveniently possible, so that upon bonded consolidation, the effective reinforcement (at D-spaced limits) is attributable to essentially twice the number of consolidated thicknesses of sheet material as that which characterizes any previously described embodiment.

FIGS. 10 and 11 illustrate a form of the invention wherein a filamentary overlay of heat-bondable material, such as filamentary polyethylene, is continuously applied as a heat lamination to the sheet 16, at the spacing D at least over the portion thereof which corresponds to the upper panel region 88. It will be understood, for example, that for l to 2-mil thick polyethylene, separate single 5-mil filaments, or separate threads of twisted filaments having substantially such bulk, may

be continuously laid upon sheet 16 passing the laminating means 45, it being optional whether the lamination is above or below sheet 16, i.e., on the outer surface or on the inner surface of the ultimately wrapped package. Such filamentary laminations are shown at -91 on the outer (upper) surface of the sheet material, being initially bonded or tacked thereto at 45, and finally bonded at 35.

FIG. 10 also serves to illustrate that the course of laminated reinforcement may undulate as a function of location around the peripheral extent of the wrap, as in accordance with the pattern of FIG. 12, which is an unshrunk sheet panel length extending from a first locus 92 of severance between a first two clusters, as cut at 31 between clusters F-G, to a second locus 93 of severance between the immediately preceding two clusters E-F. The undulating courses of reinforcement are most converged (separation D) for what synchronized feeding will develop as the top panel 88. On both limits of this top-panel region, the reinforcements diverge gradually, to what becomes a bottom-panel region of greatest separation D Preferably, the separation D slightly exceeds two container diameters, so that lifting forces via the reinforcing laminations not only directly and fully support the outer pairs 10-13 and 12-15 but also tend to stabilize their nested integration into the cluster.

In the laminating apparatus of FIG. 13, two locally squeezed wrinkles or depressions 95-96 (see also FIG.

13A) are formed at spacing D, symmetrically with re- I spect to the longitudinal center of sheet material 16, prior to local heating, as by directed discharges of hot air at 97-98, to produce beak-like laminations 99-100 (see also FIG. 13B) in sheet material fed to roller 21 for wrapping. As shown, the squeeze action involves incremental inward displacement of the two swaths of sheet 16, outward of the D-spaced central region; this uses three sets of three pairs of driven rollers, all driven in synchronism, as suggested by dashed-line interconnections. The first set of rolls 100-101-102 stabilizes feed of the full initial span S, of sheet 16, with preferably a small axial separation between adjacent sets 100-101 and 101-102, as shown. Each pair of the next set of rolls 103-104-105 operates more or less independently on a different segment of the sheet width. The center pair of rolls 104 serves to stabilize the D-space region and involves oppositely driven rolls on axes perpendicular to the displacement axis of the center of sheet 16. The outer pair of rolls 103, likewise driven in opposite directions, involves roll axes inwardly canted with respect to the axes of rolls 104 and is operative on the sheet region one side of the D-space region; the other outer pair 105, is similarly driven on inwardly canted axes on the opposite side of the D-space region. The combined action of rollsl03-l04-l05 is to inwardly bodily displace each of the outer sheet regions, toward the central D-space region, raising the local wrinkles or depressions 95-96 at substantially D-spacing. The hotair discharges consolidate or laminate these wrinkles as beads 99-100 to the adjacent sheet material, which now has a slightly reduced overall width span S The final set of rolls 106-107-108, driven on axes parallel to those of rolls 100-101-102, stabilizes all regions of the now-beaded sheet 16 for its continuous passage through the already described wrapping procedure.

FIG. 14 illustrates a modification of part of the apparatus of FIG. 5, wherein pleated formations in sheet material 110 issuing from a pleating head (as at 61) are temporarily tacked by knurl compression, i.e., by means other than the use of heat. For the purpose, I show a lower smooth cylindrical roll 111 and an upper knurl or compression roll 1 12, between which the sheet 110 is continuously fed, to produce knurl-tacked pleats 113. The tacking is sufficient to hold for the wrapping process described for clusters I through C of FIG.- I, whereupon exposure to the shrink oven 35 consolidates the wrap and the pleats, as will be understood. Preferably, the knurled roll 112 is constantly loaded by resilient means 114 against stops 115, adjustably positioned by means 116 such that a predetermined gap exists between the rolls 111-112. The gap is selected to assure knurl-compression of only the pleated region; for example, for the case of Z-mil thick polyethylene sheet 110, wherein pleat thickness is necessarily 6 mils, and for longitudinal knurl ribbings of at least 4 mils amplitude, the gap selected by adjustment at 116 should be approximately 4 mils.

The described article, method and apparatus will be seen to achieve all stated objects. In every case, local reinforcement is continuously or intermittently developed as desired, without interrupting or interfering with the swift, smooth and continuous flow of sheet material to continuously moving clusters. Obviously, the invention lends itself to a wide variety of reinforcement patterns, as varying conditions may require. And the undulating patterns of FIG. 12 may be achieved with filamentary laminations, by the simple expedient of programmed laterally displaced offset control of filamentary feeds, synchronized at 53 to the basic wrap cycle; alternatively, similar patterns of pleats may be developed by apparatus of the FIG. 5 character, utilizing for example separate laterally slidable assemblies of first and second sets of shoes 64-67-68, as described in connection with FIG. 9, the slidable assemblies being programmed for laterally undulating displacement, as described for the filamentary laminations 90-91.

In every case, the important point is that one may employ the thinnest feasible sheet material 16, compatible with the size and weight of the filled containers to be packaged. Generally, for a l2-oz. size 2 X 3" six pack, polyethylene of l to 1.5-mil thickness is-perfectly feasible, and the portability feature meets the most exacting requirements. Further, for the case of straightcourse laminations 46-47 at D-spacing, the bonded overlap of the wrap ends includes a locally bonded region aligned with laminations 46-47, being offset from the longitudinal alignment of container-pair centers; this circumstance assures full hoop strength of the reinforced region, for strong retention of package integrity and for well-distributed retention of all panel sections adjacent thereto. In like manner, the provision of the wide bottom reinforcement spacing D (at greater than two container diameters) assures completed-hoop retention via the outer bonded regions of the overlapped ends of the sheet wrap.

While the invention has been shown and described in connection with preferred forms and embodiments, it will be understood that modifications may be made without departure from the scope of the invention.

What is claimed is:

1. The method of packaging a cluster of plural like containers which comprises arranging the containers in parallel-oriented transversely aligned adjacency, selecting a length of shrinkable and bondable plastic sheet material of width exceeding the transverse extent of the cluster, forming a local relatively narrow pleat in the sheet material, said pleat extending in the length direction of the sheet, orienting the sheet material over the cluster at one end andboth adjacent sides with the longitudinal ends of the sheet material overlapped at the other end of the cluster, and exposing the thuswrapped cluster to a shrinking and bonding atmosphere for a predetermined period of time, such period of time being predetermined to assure bonded fusion of adjacent overlapped pleat and cluster-end surfaces to each other, as well as to assure concurrent shrink action of said material.

2. The method of using a continuously supplied length of shrinkable and bondable plastic sheet material to continuously package a succession of like generally rectangularly prismatic transversely arrayed clusters of articles, which method comprises selecting such sheet material of width exceeding the transverse extent of the clusters, continuously forming a pleat in the supplied sheet material, selecting for each cluster a pleated length of the sheet material, successively enveloping each succeeding cluster with the selected pleated length, the envelopment being over the cluster at one end and both adjacent sides with the longitudinal ends of the sheet material overlapped at the other end of the cluster, and continuously transporting the successively wrapped clustersthrough a shrinking andbonding atmosphere for a period of time predetermined to assure bonded fusion of adjacent overlapped pleat and cluster-end surfaces to each other as well as to assure concurrent shrink action of said material.

3. The method of claim 2, and including the step of locally heating and bonding the pleat to adjacent sheet material prior to cluster envelopment.

4. The method of claim 3, in which the local heating and bonding is a longitudinally centrally located fraction of each selected length, said method including the additional step of orienting said fractional length along the top region of cluster envelopment, whereby upon exposure to said atmosphere, the locally bonded fraction of pleated length remains as a handle reinforcement at thetop region, and whereby the shrink action in said atmosphere will dissolve the pleat at side and bottom cluster regions removed from said bonded fraction.

5. The method of claim 2, and'including the step of locally compression-tacking the pleat to adjacent sheet material prior to cluster envelopment.

6. The method of claim 2, and including the step of continuously compression-roll tacking the pleat to adjacent sheet material'prior to cluster envelopment.

7. The method of claim 2, and including the step of locally piercing single-thickness sheet material adjacent the pleated region at said'one end.

8. Means for continuously packaging like generally rectangularly prismatically arrayed clusters of articles, comprising elongated conveyor means for supporting and transporting a continuous succession of clusters in equally spaced relation, an elongated supply of flexible heat-shrinkable and bondable envelope sheet material of width exceeding the cluster width transverse to the direction of conveyor transport, sheet-engaging and manipulating means operative upon sheet material from said supply and wrapping sheet material around successive clusters in the direction such that the width dimension of said material when wrapped is symmetrical with the cluster width transverse to the direction of conveyor transport, sheet-pleating means operative on sheet material from said supply and prior to engagement by said manipulating means, a locally heated environmental region in the path of conveyor movement after cluster-wrapping, the heating being sufficient to adhere the plastic sheet to itself at local regions of end and pleat overlap and to shrink the plastic into local contour-conformance with the cluster, and intermittently operative means for locally piercing said sheet material, said piercing means being positioned and synchronized with the wrapping cycle of said manipulating means such that single-thickness sheet material is locally pierced at a predetermined location along the wrap and adjacent the pleated region.

9. Packaging means according to claim 8, in which said sheet-pleating means includes local-heating means to bond and thus retain pleating formations prior to cluster-wrapping.

10. Packaging means according to claim 9, in which said local-heating means is intermittently operative and has an intermittently operative cycle that is coextensive and synchronized with the wrapping cycle of said manipulating means, said intermittently operative cycle being operative to adhere passing pleat-overlapped material for only a predetermined fraction of the said intermittently operative cycle, thereby creating a bonded pleat of limited length, the phase relation of such synchronization being such that for each clusterwrapping operation the limited bonded pleat is located at least on the upper panel of the wrap.

11. Packaging means according to claim 10, in which the operative period of said local-heating means is the substantial equivalent of the span of the top panel in the wrap direction.

12. Packaging means according to claim 8, in which said articles are like prismatic containers and in which said sheet-pleating means includes means operative on said sheet material to define two pleats spaced substantially to the extent of the transverse dimension of each container.

13. Packaging means according to claim 8, in which said sheet-pleating means includes a pair of spaced compression rolls set in spaced relation at least to the extent of the sheet thickness of said material, said spaced relation being less than the combined multipleply thickness of the pleated region of said sheet, whereby said rolls will compress primarily only the pleated region of said sheet material.

14. Packaging means according to claim 13, in which one of said rolls has knurl formations.

15. Packaging means according to claim 13, in which said rolls are mounted for relative displacement of their axes, means preloading said rolls in the approach direction of such axis displacement, and stop means limiting the extent of such approach displacement to assure at least said spacing.

Claims

1. The method of packaging a cluster of plural like containers which comprises arranging the containers in parallel-oriented transversely aligned adjacency, selecting a length of shrinkable and bondable plastic sheet material of width exceeding the transverse extent of the cluster, forming a local relatively narrow pleat in the sheet material, said pleat extending in the length direction of the sheet, orienting the sheet material over the cluster at one end and both adjacent sides with the longitudinal ends of the sheet material overlapped at the other end of the cluster, and exposing the thus-wrapped cluster to a shrinking and bonding atmosphere for a predetermined period of time, such period of time being predetermined to assure bonded fusion of adjacent overlapped pleat and cluster-end surfaces to each other, as well as to assure concurrent shrinK action of said material.

2. The method of using a continuously supplied length of shrinkable and bondable plastic sheet material to continuously package a succession of like generally rectangularly prismatic transversely arrayed clusters of articles, which method comprises selecting such sheet material of width exceeding the transverse extent of the clusters, continuously forming a pleat in the supplied sheet material, selecting for each cluster a pleated length of the sheet material, successively enveloping each succeeding cluster with the selected pleated length, the envelopment being over the cluster at one end and both adjacent sides with the longitudinal ends of the sheet material overlapped at the other end of the cluster, and continuously transporting the successively wrapped clusters through a shrinking and bonding atmosphere for a period of time predetermined to assure bonded fusion of adjacent overlapped pleat and cluster-end surfaces to each other as well as to assure concurrent shrink action of said material.

4. The method of claim 3, in which the local heating and bonding is a longitudinally centrally located fraction of each selected length, said method including the additional step of orienting said fractional length along the top region of cluster envelopment, whereby upon exposure to said atmosphere, the locally bonded fraction of pleated length remains as a handle reinforcement at the top region, and whereby the shrink action in said atmosphere will dissolve the pleat at side and bottom cluster regions removed from said bonded fraction.

5. The method of claim 2, and including the step of locally compression-tacking the pleat to adjacent sheet material prior to cluster envelopment.

6. The method of claim 2, and including the step of continuously compression-roll tacking the pleat to adjacent sheet material prior to cluster envelopment.

7. The method of claim 2, and including the step of locally piercing single-thickness sheet material adjacent the pleated region at said one end.

13. Packaging means according to claim 8, in which said sheet-pleating means includes a pair of spaced compression rolls set in spaced relation at least to the extent of the sheet thickness of said material, said spaced relation being less than the combined multiple-ply thickness of the pleated region of said sheet, whereby said rolls will compress primarily only the pleated region of said sheet material.