WO2002036436A1

WO2002036436A1 - Adaptable packaging machine heat shrink tunnel

Info

Publication number: WO2002036436A1
Application number: PCT/US2001/044850
Authority: WO
Inventors: Claude Andrew Neagle; Jean Marti
Original assignee: Claude Andrew Neagle; Jean Marti
Priority date: 2000-11-01
Filing date: 2001-10-31
Publication date: 2002-05-10
Also published as: CA2436202A1; AU2002219946A1; EP1335857A1; CN1473125A

Abstract

A shrink tunnel (100) for use with packaging machines utilizing heat shrinkable film (17). Air plenums (158, 160, 162, 164) positioned in the shrink tunnel (100) accurately direct heat at laterally opposed ends (188, 190, 198, 200, 202, 204, 206, 208, 212, 214, 218, 220) of film wrapped packages (192, 194, 196, 210, 216, 222) to shrink film into a bullseye (19). The air plenums (158, 160, 162, 164) are adjustable to accommodate different size packages or a differing number of lanes of operation. Interior air plenums (160, 162) are inserted between packages in lanes of a multiple lane packaging machine so that the laterally opposed ends of all packages have hot air directed at them.

Description

ADAPTABLE PACKAGING MACHINE

HEAT SHRINK TUNNEL

Field of the Invention

This invention relates to an adaptable shrink tunnel that directly applies hot air to specific portions of heat shrinkable film in a

packaging machine wherein articles packaged in heat shrinkable film

are produced in alternative modes of operation of the packaging

machine including single lane, dual lane and triple lane.

Background of the Invention

The packaging of consumer and wholesale goods in heat

shrinkable film is well known, the properties of the film allowing it to be wrapped around articles before shrinking and thereafter to be shrunk

by applying heat to bring the film into tight engagement with the articles to form the package. One particular use of heat shrinkable film

in packaging is in the secondary packaging of cylindrical articles such

as bottles or cans of foods, soups, beverages, etc.

The secondary packaging of articles such as bottles or cans

generally includes a first step of arranging the articles into a group that

will eventually form a multi-pack. In many instances, the articles are

enclosed in a tray, although such enclosure in a tray is not necessary

and does not distinguish the prior art from the present invention. It is well known that film wrapped around a group of articles, whether in a

tray or not, may be heated to shrink the film and bring it into tight

engagement with the articles to form a finished multi-pack.

In a typical operation of a packaging machine incorporating heat

shrinkable film, the film is wrapped around the articles and, if included, the tray enclosing the articles, until there is an overlap seam of the two

ends of the film. The overlap seam is then sealed to form a tube

around the group of articles, the tube open at both ends. Application

of heat shrinks the tube of film to create small, generally elliptical

openings, known as bullseyes, at the laterally opposed ends of the multi-packs where the tube openings had been prior to shrinkage. To

improve the appearance and integrity of packages, it is desirable to

control the application of heat to the film in such a manner that the shrinkage is uniform and results in bullseyes that are uniformly shaped

and properly positioned at the laterally opposed ends of the multi- pack.

A development in the shrink wrap packaging of articles incorporates the use of heat shrinkable film with letters, numbers,

logos, etc., imprinted on the film. If the shrinkage of the film is not

precisely controlled, any printing (letters, numbers, logos, etc.) on the film will be distorted and the package will be unattractive. If anything

imprinted on the film is to be machine read and used for automatic

processing of the package, such as a bar code, non-uniform shrinkage

that distorts the imprinted matter negatively affects the further

processing and handling of the package. In addition, if the shrinkage

is not controlled and the bullseye is not properly formed, resulting in

articles that are loose or not substantially enclosed by the film after

shrinkage, the integrity of the multi-pack will be at risk as it is

transported and handled from wholesaler to retailer to consumer.

In prior art packaging machines it has been common to shrink the film by passing the film wrapped group of articles through a shrink

tunnel or chamber wherein the ambient air temperature is sufficiently

high and the dwell time sufficiently long to shrink the film into tight engagement with the group of articles. Non uniformity and an inability to control the shrinking of the film are the predictable results of such ambient air heating. It has become known that controlled application

of hot air directed at the tube openings at the ends of a film wrapped

group of articles gives more control over the shrinkage of the film and

results in improved uniformity of the bullseye and improved integrity of

the package.

As the need for packaging machines to be flexible to produce

different size, orientation and arrangement of packages has

developed, new problems have arisen in the heating and shrinking of

film. The prior art has addressed the problem of adjustable methods

and devices for controlling the application of hot air to heat shrinkable film only in a limited manner. In U.S. Patent No. 5,546,677 to Tolson, nozzles with flexible hot air ducts to accommodate different width

packages are provided. Hot air is directed upwardly from below the

package pass-line at the edges of the packages being processed to

control the heating of the sides of the film. The position of the nozzles may be adjusted to accommodate packages of differing widths.

As discussed above, a common application of heat shrinkable

film to enclose a group of articles is the secondary packaging of

bottles or cans, including beverages, into multi-packs of six, twelve,

twenty four or other numbers of articles. The integrity and appearance of the packaging of articles such as cans or bottles into multi-packs is

primarily dependent upon the integrity of the bullseyes formed in the laterally opposed ends of the packages, so the control of the formation

of the bullseyes must be an important consideration in the design of a

packaging machine utilizing heat shrinkable film. It has been determined that, while more controlled heating of the ends of the tube

results when hot air is directed at the ends by nozzles, the exclusive

use of such nozzles shrinks the ends without fully shrinking the interior

areas of the packages, resulting in uneven shrinkage of the film in

different areas of the package. In addition, the use of nozzles to direct hot air at a specific part of the package and film limits the machine to a

specific size or arrangement of package because the nozzle has to be

in a different position to accommodate different size packages.

The problems associated with using hot air nozzles directed at

the ends of the film tube are particularly acute in packaging machines that are alternatively operable as a single lane machine, which requires nozzles directed at two package ends, or as a dual lane

machine, which requires nozzles directed at four package ends. To

direct hot air at the ends of all the packages being processed it is

necessary to insert and remove interior nozzles between the between

the lanes that direct hot air at the interior ends of the film tubes. The necessity to insert and remove hot air nozzles to accommodate a

differing number of lanes has not been previously addressed in the means . While adjustability has been addressed in the limited manner

discussed above with respect to differing width packages, it has not

been addressed for machines that handle a differing number of

packaging lanes.

It is thus desirable to design a shrink tunnel for use with film

wrap packaging machines that provides for overall heating and

shrinking of film in an ambient environment and also for the application of hot air directly to control heating and shrinking of film at the laterally opposed ends of the packages. To accommodate a broad range of

packaging machines, it is also desirable to provide a shrink tunnel that

is flexible and which can accommodate different modes of operation

including single lane, dual lane, or multiple lane. While it is desirable

to provide a flexible packaging machine that can process either a single lane of packages or dual or multiple lanes of packages, it

becomes problematic to controllably shrink the film wrapped around

multiple lanes of packages because to direct hot air at the interior ends

of the packages, hot air must be supplied and delivered between lanes of packages so that uniform heat shrinkage at both laterally opposed

ends of all the packages being processed occurs. Insofar as adjustable machines that can operate in a single lane mode of

operation or multiple lane mode of operation have only recently been

developed, as patented in U.S. Patent 5,765,336 to Neagle, the problem of alternatively heat shrinking either a single lane or multiple

lanes of packages wrapped in film has gone unaddressed.

There is thus identified a need for a shrink tunnel that is flexible

wherein hot air is applied ambiently and directly at laterally opposed

ends of packages wrapped in heat shrinkable film whether the

packaging machine is operating in a single lane mode, dual lane mode, or multiple lane mode.

Objects of the Invention

It is an object of the present invention to provide a shrink tunnel

for a packaging machine wherein heat is applied in an ambient

environment for overall shrinkage of film and directly at specific

portions of the tube to increase control of the shrinkage.

It is another object of the present invention to provide a

packaging machine having an adjustable shrink tunnel to accommodate single lane packaging, dual lane packaging or multiple

lane packaging.

It is another object of the present invention to provide a shrink tunnel for use with heat shrinkable film wherein the shrink tunnel has

laterally adjustable plenums to accommodate differing widths of packages by applying hot air to the laterally opposed ends of packages.

It is yet another object of the present invention to provide a

shrink tunnel for use with a packaging machine that provides

adjustable plenums to accommodate single lane packaging or multiple

lane packaging.

It is a further object of the present invention to provide a shrink

tunnel for use with packaging machines that provides adjustable

plenums to accommodate single lane packaging, dual lane packaging

or multiple lane packaging modes of operation.

It is a further object of the present invention to provide a shrink tunnel having an ambient hot air pre-shrink zone and a controlled heat

zone that is adaptable to single lane, dual lane or multiple lane modes

of operation of the packaging machine.

It is yet another object of the present invention to provide a

shrink tunnel providing for the controlled application of hot air directly at laterally opposed ends of packages being processed to create

consistent and uniform bullseyes therein.

It is another object of the present invention to provide a shrink tunnel having adjustable air plenums that control the direction and

application of hot air to heat shrinkable film wrapped around groups of articles being packaged.

It is a further object of the present invention to provide a

packaging machine having an adjustable controlled heat zone that is

adaptable to accommodate operation of an associated packaging

machine in single lane or dual lane modes of operation.

These and other objects and advantages of the present

invention will be apparent from a review of the following specification

and accompanying drawings.

Summary of the Invention

The present invention comprises a shrink tunnel associated with

a machine for forming packages from groups of articles that are

wrapped in heat shrinkable film. The shrink tunnel has multiple zones comprising an ambient air pre-shrink zone and a controlled heat zone,

limited overall shrinkage of the film occurring in the pre-shrink zone so that precise control of the shrinkage occurs in the controlled heat zone

by specifically directing hot air at laterally opposed ends of packages being processed. The formation of bullseyes in the laterally opposed

ends of the package, from shrinkage of the open ends of a tube of heat shrinkable film formed after wrapping and lap sealing the film around the articles, is improved and made more consistent through the use of

the controlled heat zone.

In the most preferred embodiment of the present invention, the

means for applying hot air to the laterally opposed ends of packages

comprises multiple air plenums having apertures therein that are

formed and positioned to direct hot air exiting therefrom at laterally

opposed ends of the packages wrapped in heat shrinkable film. The

shrink tunnel is adaptable to provide controlled heating and shrinking

of film when operated in either single lane or dual lane modes of

operation.

The shrink tunnel of the present invention comprises means for

adjusting the positions of air plenums that direct hot air as necessary

at laterally opposed ends of film wrapped packages being processed

thereby to accommodate single lane mode or dual lane mode of

operation of a packaging machine.

The present invention provides shrink tunnel that

accommodates operation in single lane, dual lane or triple lane mode

through the use of multiple air plenums that have adjustable positions

within the shrink tunnel. Specifically, the air plenums are adjustable

along position bars and are locked into place to accommodate the desired mode of operation.

The shrink tunnel of the present invention is particularly advantageous when used with a shrink wrap packaging machine that

is adjustable between single lane and dual lane modes of operation.

The means for adjusting the shrink tunnel of the present invention to

accommodate single lane and dual lane modes of operation is

simplified and does not require complex mechanical adjustments or the

addition or removal of equipment. The shrink tunnel of the present

invention controls the application of hot air to heat shrinkable film,

resulting in improved appearance and reliability of the finished package, but it further includes the means for adjusting those hot air

application means so that, even if the packaging machine operation

changes from single lane to dual lane, the same control of hot air application is retained.

Brief Description of the Drawings

Figure 1 is a schematic illustrating single lane packaging of

cylindrical articles into a multi-pack.

Figure 2 is a schematic illustrating dual lane packaging of

cylindrical articles into two multi-packs.

Figure 3 is a perspective view of a shrink tunnel illustrating the passage of film wrapped packages therethrough to form finished multi-

packs.

Figure 4 is a front schematic view of a shrink tunnel illustrating

the components, zones and application of hot air to film wrapped packages processed therein.

Figure 5a is a front sectional view along lines 5-5 of Figure 4

illustrating single lane mode of operation in the associated packaging

machine and shrink tunnel.

Figure 5b is a front sectional view along lines 5-5 of Figure 4

illustrating dual lane mode of operation in the associated packaging

machine and shrink tunnel.

Figure 5c is a front sectional view along lines 5-5 of Figure 4

illustrating triple lane mode of operation in the associated packaging

machine and shrink tunnel.

Detailed Description of the Invention

Figure 1 of the drawings illustrates single lane packaging of

cylindrical articles 10 to form a finished multi-pack 12. The basic steps

in creating the multi-pack 12 include grouping the articles 10 at a collation section 14, forming a tray 15 around the articles 10 at

trayformer section 16, wrapping the articles 10 in a tube of heat shrinkable film 17 at film wrap section 18, and applying hot air at shrink section 20. The tube of film 17 is a sheet of heat shrinkable

film wrapped around articles 10 that is lap sealed as will be explained in greater detail herein and has openings at laterally opposed ends.

Application of hot air to the tube of film 17 causes the openings to

shrink to create smaller essentially elliptical openings known as

bullseyes 19 in the laterally opposed ends of the finished multi-pack

12. While Figure 1 illustrates the use of a tray 15 around the articles

10, it is specifically contemplated that the principles of the present invention may be used with or without a tray or trayforming apparatus.

Figure 2 is a schematic illustrating dual lane packaging of

articles 50 to form two finished multi-packs 52, 54. In dual lane

operation, articles 50 are grouped at a collation section and subsequently split into two groups and placed into trays at trayformer

section 56. Tubes of heat shrinkable film are then applied at film wrap

section 58. Hot air is applied at shrink section 60 to form two finished

multi-packs 52,54, each having bullseyes in laterally opposed ends

after shrinkage of the film. While Figure 2 illustrates the use of trays

around the articles, it is specifically contemplated that the principles of

the present invention may be used with or without a tray or trayforming

apparatus. A machine that is adaptable to package articles in either single lane mode, as shown in Figure 1 , or in dual lane mode, as

shown in Figure 2, is disclosed in U.S. Pat. No. 7,565,336 to Neagle. The means for adjusting the shrink tunnel of the present invention to accommodate single lane and dual lane modes of operation is

simplified and does not require complex mechanical adjustments or the

addition or removal of equipment. The shrink tunnel of the present

invention controls the application of hot air to heat shrinkable film,

resulting in improved appearance and reliability of the finished

package, but it further includes the means for adjusting those hot air

application means so that, even if the packaging machine operation changes from single lane to dual lane, the same control of hot air

application is maintained.

While the schematics in Figure 1 and Figure 2 show single and dual lane modes of packaging articles, the present invention

comprises a shrink tunnel that can accommodate a packaging machine having three lanes or more. The applicant has developed a single

shrink tunnel that is flexible and can be converted and used with

packaging machines that are operable in a single lane mode of operation, a dual lane mode of operation, or a triple lane mode of

operation, to produce multi-packs having consistent and uniform

bullseyes formed therein, improving the integrity of the packages produced thereby. It is also specifically contemplated that the principles of the present invention may be applied to more than three lanes of operation through the addition of more air plenums, as will be

discussed in more detail herein. The present invention is directed to improvements in the

heating and shrinking of heat shrinkable film around multi-packs. It has been discovered that uniform shrinkage of film results from

multiple stage heating of the film wherein heat is first applied in an

ambient hot air environment that provides overall shrinkage of the film,

followed by controlled heating of specific portions through the

controlled and directed application of hot air. In a packaging machine

that is convertible between single and dual lane modes of operation, it is necessary to provide flexible means for directing heat so that, when

converting to change the number of lanes of operation, it is still possible to control the directed hot air to produce the uniform single

lane multi-pack 12 shown in Figure 1 or the dual lane multi-packs 52,

54 shown in Figure 2. It is desirable to apply hot air directly and

uniformly at the laterally opposed ends of the heat shrinkable tube of

all multi-packs so that bullseyes are formed in both laterally opposed

ends of packages, whether in single lane, dual lane or more multiple

lane modes of operation. The shrink tunnel 100 shown generally in Figure 3 illustrates dual lane mode of operation of a packaging machine. Two multi-packs

102,104 wrapped in tubes of heat shrinkable film are shown prior to

shrinkage and after shrinkage, the flow through the shrink tunnel being

in the direction indicated. The tube of heat shrinkable film formed around each multi-pack 102,104 includes an overlap 106 formed in a

preceding film wrap section of an associated packaging machine.

After wrapping articles in heat shrinkable film, such as multi-packs 102,104, the first step in shrinking the heat shrinkable film to create a

finished multi-pack is to lap seal the overlaps 106 together. The film thereafter comprises tubes around the articles being packaged that are open at both laterally opposed ends. Means for sealing the overlap

106 is provided by a blower 108 that moves air across heating elements 100 in the direction shown (Figure 4). The hot air produced

thereby is directed at the film overlap 106 located under the multi-pack

or multi-packs by duct 112 and lateral nozzle 114 which extends

substantially all the way across the width of the shrink tunnel 100.

Next, overall heating and shrinking of the tubes of film is

accomplished in an ambient pre-shrink zone 120 provided in the shrink

tunnel 100 wherein a blower 122 moves air across heating elements

124. Hot air produced by blower 122 and heating elements 124 is distributed within zone 120 by ductwork 126 and distribution baffle

128. While Figure 4 illustrates a single run of ductwork 126 and baffle 128, it is specifically contemplated that more elaborate means for

distributing heated air in the ambient pre-shrink zone may be

employed without departing from the principles of the present invention. The ambient pre-shrink zone 120 is similar to prior art

shrink tunnels wherein overall shrinkage of the film tube occurs. In the

ambient pre-shrink zone 120 of the present invention the temperatures

and dwell times are maintained such that some limited overall

shrinkage occurs without shrinking the tube of heat shrinkable film into tight engagement with the articles.

The most preferred embodiment of the present invention provides a means for heating the laterally opposed ends of the

packages to produce uniform bullseyes in heat shrinkable film

wrapped around them. Specifically, a shrink tunnel 100 is provided with a controlled heat zone 150 in which hot air is precisely controlled

and specifically directed at the laterally opposed ends of packages being processed. It is a significant feature of the present invention that

the final heating and shrinkage of the film tube occurs in the controlled

heat zone 120 wherein the application of hot air is more precise.

Hot air used in the controlled heat zone 150 is supplied by a blower 152 which moves air across heating elements 154 and through

a main duct 156. Out of main duct 156, hot air is directed to apply

heat to laterally opposed ends of packages wrapped in tubes of heat

shrinkable film by four air plenums 158,160,162,164 and flexible ducts 166, 168, 170, 172 in the most preferred embodiment of the present

invention (Figures 5a-5c). The flexible ducts 166, 168, 170, 172

provide the flexible means for delivering hot air to multiple apertures

165 formed in the plenums 158, 160, 162, 164. The ducts 166, 168,

170, 172 are flexible and air-tight and allow the plenums 158, 160, 162, 164 to be freely adjusted to accommodate packages of different

sizes, or to accommodate packaging in a single lane, dual lanes or

multiple lanes.

The multiple apertures 165 are formed in rows near the bottoms

of the plenums 158, 160, 162, 164 to provide the means for directing hot air at the laterally opposed ends of the film tubes wrapping the

packages being processed to control shrinkage of film to create

bullseyes in the laterally opposed ends of the finished film wrapped

packages. An intermediate distribution chamber 174 is provided

between the main duct 156 and the four plenums 158, 160, 162, 164 which comprises means for shutting off air to the four plenums 158,

160, 162, 164 independently of one another depending on the number lanes and mode of operation of the associated packaging machine. Shut off valves 176, 178, 180, 182 are provided at the air exit of the

distribution chamber 174 that may be closed to interrupt air flow to the

plenums 158, 160, 162, 164 as necessary or desired.

Means for adjusting the positions of the plenums 158, 160, 162,

164 are provided in the preferred embodiment of the present invention

so that the shrink tunnel 100 is adaptable to provide controlled heating

at laterally opposed sides of packages being processed when operated in single lane mode, dual lane mode or triple lane mode of

operation. Specifically, the plenums 158, 160, 162, 164 are hung from

and are adjustable on position bars 184, 186 that extend laterally across the expanse of the shrink tunnel 100 and which are

incorporated into the structure and supported by the shrink tunnel 100.

The positions of the plenums 158, 160, 162, 164 are laterally

adjustable and lockable along the length of the position bars 184, 186

to accommodate single lane operation as shown in Figure 5a, dual

lane operation as shown in Figure 5b, and triple lane operation as

shown in Figure 5c. It is specifically contemplated that additional plenums may be added to accommodate more lanes of packaging

without departing from the principles of the present invention.

Single lane operation of the shrink tunnel 100 is illustrated in Figure 5a wherein the two interior plenums 160, 162 are used to apply hot air to the opposed lateral ends 188, 190 of the package 192 as

shown (see Figure 5a directional arrows). The plenums 160, 162 are positioned along position bars 184, 186 to accommodate the width of a

single film wrapped package 192. In single lane operation, shut off

valves 176, 182 are provided as a means to cut off air to the unused

outer plenums 158, 164.

Figure 5b illustrates dual lane operation in the shrink tunnel 100 wherein interior plenum 162 is positioned between the two lanes

represented by film wrapped packages 194, 196. The use of three

plenums 160, 162, 164 provides a means for directing hot air at the laterally opposed ends 198, 200 of package 194, as well as the

laterally opposed ends 202,204 of package 196. Hot air is specifically directed as shown (see Figure 5b directional arrows) at the laterally

opposed ends 198,200,202,204 to create uniform bullseyes in both laterally opposed ends of both packages 194, 196 being processed in

dual lane mode of operation. Interior plenum 162 is provided with

bidirectional hot air supply apertures 165 (see Figure 5b) to apply hot air to the interior laterally opposed ends 202, 204 of the two packages

194, 196 being processed in dual lane mode. The presence of

apertures 165 on both sides of the interior plenum 162 is a feature of the present invention allowing a packaging machine to be converted

from single lane to and from dual lane modes while retaining the benefit of directly applying hot air at the laterally opposed ends of the

packages for final shrinkage of the film tube. In dual lane mode, the

shut off valve 176 is closed to cut off air to unused plenum 158, while

the other three shut off valves 178, 180, 182 are open.

In the triple lane mode of operation of the shrink tunnel 100, four air plenums 158, 160, 162, 164 provide the means to direct hot air

at laterally opposed ends 206, 208 of first lane package 210, at

laterally opposed ends 212, 214 of second lane package 216, and at

laterally opposed ends 218, 220 of third lane package 222. Bullseyes

that are consistent are thus created in the laterally opposed ends of all three packages 210, 216, 222. Both interior plenums 160, 162 are

provided with bidirectional hot air supply apertures 165 on both sides

to ensure controlled heating of the laterally opposed ends 208, 212,

214, 218 of the packages 210, 216, 222 being processed in triple lane

mode of operation. The adjustable and lockable positions of the air

plenums 158, 160, 162, 164, along with the bidirectional hot air supply

apertures 165 on the interior plenums 160, 162 provide the means for

adjusting the shrink tunnel to accommodate operation of a packaging machine in single lane mode, dual lane mode and triple lane mode without requiring complex mechanical adjustment or addition or removal of equipment to the machine.

The air plenums 158, 160, 162, 164 provide an improved means

for controlling the direction of hot air to shrink laterally opposed ends of heat shrinkable film to create repetitive and consistent bullseyes

and to remove the uncertainty of relying on uniform shrinking in an ambient air environment. This improves product appearance,

particularly for film with numbers, print, bar codes, logos, etc.,

imprinted thereon. It also improves product integrity because the likelihood of exposed and unenclosed articles resulting from

uncontrolled shrinkage of the film is reduced.

Providing the adjustable plenums 158, 160, 162, 164 also

allows the shrink tunnel to be adapted to accommodate various

configurations of a packaging machine. Specifically, the preferred

embodiment of the present invention is adaptable for use in single

lane, dual lane or triple lane modes of operation, although the use of more than three lanes of operation with additional adjustable plenums

is specifically contemplated so that the use of adjustable, retractable or

selectable air plenums to accommodate a packaging machine or shrink

tunnel with more than three lanes is not a departure from the principles

of the present invention. As discussed above, ambient air shrinking of the film overall occurs in the pre-shrink zone 120, but the overall shrinking is limited

so that application of hot air in the controlled heat zone 150 provides the final shrinkage of the film to bring the film into tight engagement

with and enclosure of the articles being packaged and to create the

desired uniform bullseyes. By being positioned in the shrink tunnel

downstream from the pre-shrink zone 120, the adjustable plenums

158, 160, 162, 164 provide the means for tightly controlling the

shrinkage of the laterally opposed ends of film to create uniform

bullseyes in the finished packages whether the packaging machine is

operating in single lane, dual lane, triple lane or more multiple lanes mode. The plenums 158, 160, 162, 164 are adjusted and locked to

allow the packaging machine and shrink tunnel to be utilized to process packages of differing widths. By adjusting the spacing of the

plenums 158, 160, 162, 164 on the position bars 184, 186, the

distance between them and the laterally opposed ends of the film can be defined to maximize the control of the heating and shrinking of the

laterally opposed ends of the film.

The foregoing description of a preferred embodiment of the

invention has been presented for purposes of illustration and

description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are

possible in light of the above teachings. The embodiment was chosen

and described in order to best illustrate the principles of the invention

and its practical application to thereby enable one of ordinary skill in

the art to best utilize the invention in various embodiments and with

various modifications as are suited to the particular use contemplated.

It is intended that the scope of the invention be defined by the claims

appended hereto.

Claims

I claim:

1. A shrink tunnel (100) associated with a film wrap packaging

machine utilizing heat shrinkable film comprising:

a pre-shrink zone (120); and a controlled heat zone (150).

2. The shrink tunnel (100) as set forth in Claim 1 wherein said pre-

shrink zone (120) comprises an ambient heating environment wherein

limited overall shrinkage of the heat shrinkable film occurs.

3. The shrink tunnel as set forth in Claim 2 wherein said controlled heat zone (150) comprises means (158, 160, 162, 164, 166, 168, 170,

172) for applying hot air that is precisely controlled and specifically directed at laterally opposed ends (188, 190, 198, 200, 202, 204, 206, 208, 212, 214, 218, 220) of packages being processed.

4. The shrink tunnel as set forth in Claim 3 wherein said means (158, 160, 162, 164, 166, 168, 170, 172) for applying hot air is flexible to

allow said packaging machine to be operated in both single lane mode

and dual lane mode.

5. The shrink tunnel as set forth in Claim 4 wherein said means (158,

160, 162, 164, 166, 168, 170, 172) for applying hot air further comprises multiple air plenums (158, 160, 162, 164) having apertures

(165) therein directing hot air at said laterally opposed ends (188, 190,

198, 200, 202, 204, 206, 208, 212, 214, 218, 220) of said packages.

6. The shrink tunnel as set forth in Claim 5 further comprising means

(184, 186) for adjusting positions of said air plenums (158, 160, 162,

164).

7. The shrink tunnel as set forth in Claim 6 wherein said adjusting

means comprises position bars (184, 186) extending across said

shrink tunnel (100).

8. The shrink tunnel as set forth in Claim 7 further comprising means for locking said air plenums into position on said position bars.

9. The shrink tunnel as set forth in Claim 8 further comprising means

(184, 186) for adjustment to accommodate operation of a packaging machine in single lane mode, dual lane mode and triple lane mode.

10. A machine (100) for packaging articles into multi-packs operable

in single lane and dual lane modes comprising: a film wrap section (58) wherein tubes of heat shrinkable film

(17) are formed around each of said multi-packs; a heat shrink tunnel (100); and

means (158, 160, 162, 164, 166, 168, 170, 172) for directing hot

air at specific portions of each of said multi-packs.

11. The machine for packaging as set forth in Claim 10 wherein said

means (158, 160, 162, 164, 166, 168, 170, 172) for directing hot air

comprises means for directing hot air at laterally opposed ends (188,

190, 198, 200, 202, 204) of each of said tubes whether said machine is

operating in single lane mode or dual lane mode.

12. The machine for packaging as set forth in Claim 11 wherein said

means (158, 160, 162, 164, 166, 168, 170, 172) for directing hot air

further comprises adjustable air plenums (158, 160, 162, 164) directing

hot air at said laterally opposed ends (188, 190, 198, 200, 202, 204).