US3616548A - Apparatus for shrink packaging - Google Patents

Abstract

A SHRINK TUNNEL FOR HEAT SHRINKING WRAPPING MATERIAL ABOUT ARTICLES BY INTRODUCING HEATED AND PRESSURIZED AIR THROUGH SPACED PERFORATED DISCHARGE MEMBERS WITHIN THE TUNNEL WHEREBY THE AIR IS DISTRIBUTED AGAINST AT LEAST THE TOP AND SIDES OF THE HEAT SHRINKABLE MATERIAL WITH SUBSTANTIALLY EQUALIZED VOLUME AND VELOCITY TO UNIFORMLY SHRINK THE MATERIAL AROUND THE ARTICLES.

Description

Nov. 2, 1971 J. A. NICHOLS 3,616,543

APPARATUS FOR SHRINK PACKAGING Filed June 2, 1970 3 Sheets-Sheet 1 mvnrron JOHN A. NICHOLS mr Ea Wynn, fi m/029012 d(% 60w Nov. 2, 1971 J. A. NICHOLS 3,616,543

' APPARATUS FOR SHRINK PACKAGING Filed June 2. 1970 SSheets-Sheet mvnu'ron JOHN A. NICHOLS- BY ZZ IKy fllII/MSOI? Nov. 2, 1971 Filed June 2. 1970 APPARATUS A. NICHOLS 3,616,548

FOR SHRINK PACKAGING I 3 fihlewf 5 PATH DIRECTION 0 o o o o o o 0 o o o o o o o 0 l0 0 O 0 O o o 0/ N I o o 0 3| 0 P0 o o o o o ..-o o 0 o o ;o o 0 0 0 L U 3| 33 INVENTOR JOHN A. NICHOLS V hfimywz, f/e/zamm @7022504) ATTORNEYS United States Patent Office 3,616,548 Patented Nov. 2,, 1971 3,616,548 APPARATUS FOR SHRINK PACKAGING John A. Nichols, Canton, Mass., assignor to Mill Industries, Inc., Shreveport, La. Continuation-impart of application Ser. No. 781,440, Dec. 5, 1968. This application June 2, 1970, Ser.

Int. Cl. F26b 19/00 U.S. Cl. 34233 3 Claims ABSTRACT OF THE DISCLOSURE This application is a continuation-in-part of the application Ser. No. 781,440, filed Dec. 5, 1968, for Apparatus for Air-Treating Sheet Material Surfaces and the Like.

This invention relates to apparatus for shrinking heat shrinkable wrapping materials about articles and more particularly to shrink tunnel apparatus in combination with a unique air distribution arrangement that includes spaced perforated discharge members at least along the side walls and along the top surface of the tunnel whereby heated air is passed through the discharge members into the tunnel and against the top and sides of the heat shrinkable material with substantially equalized volume and velocity to uniformly shrink the material around the articles.

Shrink tunnel apparatus has become increasingly popular for packaging articles. The articles are initially covered by a loosely fitting heat shrinkable wrapping material, such as plastic, and are then passed through a shrink tunnel which directs heated air at a relatively high velocity directly against the surface of the material in such a manner that the material shrinks to tightly engage the articles. This method of packaging is highly desirable since it ideally provides a moisture-proof, soil-proof and attractive package. Furthermore, if a transparent heat shrinkable material is used attractive coloring or advertising on the articles themselves is still visible.

However, problems have arisen in the use of presently known shrink tunnels that do not equally distribute the heated air in volume and velocity against the surfaces f the heat shrinkable wrapping material as it surrounds the articles to be packaged. Unequal and uneven volume and velocity air-flow distribution has resulted in uneven heating and shrinking of the wrapping materials. This has resulted in packages that are not tightly sealed and which allow moisture and direct to contact and spoil the utility or appearance of the articles. Packages that are unevenly wrapped also result in frequent damage to the articles during transportation thereof since loose portions of the heat shrinkable material are easily snagged and torn.

Thus, it is extremely important in heat-shrink packaging of articles that a substantially equalized volume and velocity of heated air be distributed against the surfaces of the wrapping material so that uniform shrinking of the material into a tight and attractive conforming fit with the articles is achieved. The present invention recognizes this problem and provides a unique apparatus for solving it.

Accordingly, it is an object of the present invention to provide apparatus for heat shrinking Wrapping material about articles whereby heated air is distributed at l ast against the top and sides of the material with substantially equalized volume and velocity to uniformly shrink the material around the articles.

Another object is to provide apparatus for heat-shrink packaging of articles whereby substantially moistureproof, soil-proof and attractive packages are provided.

A further object of the invention is to provide apparatus for uniformly shrinking wrapping material about articles whereby uniform shrinkage of the materials into a tight, attractive, conforming fit with the articles is accomplished and whereby the number of articles wrapped per unit time is increased as compared to presently known heat-shrink apparatus.

Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages are realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

To achieve these objects the present invention provides at least along the side Walls and along the top surface of a heat shrink tunnel a pair of perforated discharge members spaced from one another and in communication with a source of pressurized heated air. The heated air is distributed with substantially equalized volume and velocity through the discharge members against the top and sides of heat shrinkable wrapping material surrounding articles to be packaged to uniformly shrink the material around the articles. This unique combination of a shrink tunnel with an equalized air distribution arrangement provides uniform heating of the heat shrinkable material and avoids localized underor overheating. This also provides the advantage of a tightly conforming fit of the material around the articles and provides a substantially moistureproof, soil-proof, and attractive appearing package. Further, by uniformly distributing the heated air over the wrapping material the speed of travel of the articles through the tunnel may be rapidly increased as compared with previously known tunnels without uneven heating and shrinking of the wrapping material. This, of course, markedly increases the number of articles that can be packaged per unit of time and also increases the efficiency of the packaging process.

As embodied and broadly described the invention comprises a tunnel having a passage formed of at least two apertured side Walls and an apertured top wall; means for transporting articles to be wrapped along a path direction through the passage; the side and the top walls each including a first chamber and a pair of perforated discharge members spaced from one another to form a second chamber; a first one of the members having a plurality of perforations extending in a line and substantially transversely of the path direction and communicating directly through the perforations with the first and second chambers; a second one of the members having staggered rows of perforations, each row extending substantially transversely of the path direction and the perforations in the staggered rows communicating directly with the second chamber and With the passage; and means for introducing pressurized, heated air into the first chamber, into the second chamber and through the first and second member perforations whereby the heated air is distributed against the top and sides of the heat shrinkable material with substantially equalized volume and velocity to substantially uniformly shrink the material around the articles.

It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory but are not restrictive of the invention.

In the drawings:

FIG. 1 is a perspective view of a shrink tunnel incorporating the features of this invention;

FIG. 2 is a sectional view of the embodiment shown in FIG. 1 taken along the line 22 and looking in the direc tion of the arrows;

FIG. 3 is a fragmentary perspective view showing the top and a part of one side wall of the shrink tunnel;

FIG. 4 is a detailed view of one of the pair of perforated discharge members of this invention; and

FIG. 5 is a detailed view of the other perforated discharge member.

With reference now to the drawings, wherein like reference characters designate like or corres onding parts throughout the several views, there is shown in FIG. 1 a shrink tunnel having an outer casing 12 and a passage therethrough formed of two side walls 14 and a top surface 16.

Means are provided in operative relationship with the tunnel for transporting articles along a path direction through the passage. As here embodied, the transporting means is conveyor assembly 18 that includes lateral supporting members 22 mounted on endless belts 20 whereby the articles 24 to be packaged are transported by the conveyor along a predetermined path direction through the passage.

The side walls 14 and top wall 16 of the tunnel are similar in structure and for convenience only the top wall construction will be explained in detail, it being understood that the side walls are constructed in a similar manner. The relationship between the side walls and the top wall is best illustrated in FIG. 2.

In accordance with a preferred embodiment of the invention, top surface 16 includes a first chamber 26 and a pair of perforated discharge members 31 and 33 vertically spaced from one another to form a second chamber 34. Member 31 has a pluralit of perforations 31' formed in a line that extends substantially transversely of the path direction. The perforations communicate directly with first chamber 26 and with second chamber 34. The second one of the members 33 has a staggered row of perforations 33 that also extends substantially transversely of the path direction. Each of the perforations 33' communicates directly with second chamber 34 and with the passage of the tunnel. Preferably, perforations 33 are offset from and are placed on alternating sides of an imaginary midline that is located directly below the row of perforations 31' in first member 31. This greatly enhances the equal distribution of air flow within the passage and avoids the straight uninterrupted flow of air from perforations 31' through perforation 33'.

Means are also provided in fluid communication with first chamber 26 for introducing pressurized heated air into the first chamber, into second chamber 34 and through the first and second member perforations whereby the heated air is distributed against the top and sides of the heat shrinkable material surrounding the articles 24 with substantially equalized volume and velocity to substantially uniformly shrink the material around the articles. As here embodied, the introducing means are ducts 36 and 36' that are preferably connected to a source of heated air (not shown). The pressurized hot air is directed through ducts 36 and 36', through first perforated discharge members 31 that extend transversely across the path direction and through second perforated discharge members 33 that also extend transversely across the path direction. By using second perforated discharge members 33 spaced from first discharge members 31, the pressurized air is caused to be discharged uniformly across the heat shrinkable material as the articles pass through the tunnel, and the heated air is evenly distributed across the material in substantially equalized volume and velocity.

The invention, thus, provides an unique air distribution system in combination with a shrink tunnel whereby heated air is distributed against the top and sides of heat shrinkable wrapping material surrounding articles to be packaged and whereby a substantially equalized volume and velocity of heated air is applied uniformly to the material so that it shrinks in a uniform manner to provide a substantially moisture-proof, soil-proof and attractive package.

The invention in its broader aspects is not limited to the specific details as shown and described and departures may be made from such details without departing from the principles of the invention and without sacrificing its chief advantages.

What is claimed is:

1. Apparatus for shrinking heat shrinkable material about articles, comprising:

a tunnel having a passage formed of at least two side walls and a top surface;

means in operative relationship with said tunnel for transporting said articles along a path direction through said passage;

said side walls and said top surface each including a first chamber and a pair of perforated discharge members spaced from one another to form a second chamber;

a first one of said members having a plurality of perforations extending in straight lines substantially transversely of said path direction and communieating directly through said perforations with said first and second chambers;

a second one of said members having staggered rows of perforations, said rows extending substantially transversely of said path direction and said perforations in said staggered rows communicating directly with said second chamber and with said passage; and

means in fluid communication with said first chamber for introducing pressurized, heated air into said first chamber, into said second chamber and through said first and second member perforations whereby the heated air is distributed against the top and sides of said heat shrinkable material with substantially equalized volume and velocity to substantially uni formly shrink said material around said articles.

2. Apparatus as in claim 1 wherein the perforations in said second discharge member are offset from and are placed on alternating sides of an imaginary midline that is located directly below each row of said perforations in said first discharge member.

3. Apparatus as in claim 2 wherein the first chambers in each of said side walls and said top surface are in fluid communication with each other.

References Cited UNITED STATES PATENTS 2,334,232 11/1943 Wells 34-233 X 3,222,800 12/1965 Siegel et al. 34-225 X 3,309,835 3/1967 Peppler 34225 X 3,399,506 9/1968 Howe 34225 X CARROLL B. DORITY, JR., Primary Examiner

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