US20050235609A1

US20050235609A1 - Method and apparatus for film encapsulation of irregularly shaped articles

Info

Publication number: US20050235609A1
Application number: US10/829,904
Authority: US
Inventors: Larry French
Original assignee: ERNEST PAPER PRODUCTS CORP
Current assignee: ERNEST PAPER PRODUCTS CORP
Priority date: 2004-04-21
Filing date: 2004-04-21
Publication date: 2005-10-27

Abstract

A method and apparatus for shrink-wrapping a heat sealable thermoplastic film about regular and irregular shaped articles is provided, wherein the film is provided above and below the article, one or more heat-sealing blades are generally configured to the article exterior contour to heat seal the film material about the article, the heat-sealing blade having an electrically actuated healing element within insulated material, and the spacing of the heat-sealing blade adjacent the article is intentionally non-uniform in predetermined manner. A contoured heat-sealing blade assembly is provided within split-molds, which may have associated heating ports to control the temperature of the sealing operation within different zones of the mold.

Description

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for heat sealing thermoplastic film about regular and irregular shaped articles, more particularly the method and apparatus relate to shrink wrap packing processes, which form fit heat sealable plastic films around the profile of regular and irregular shaped articles. This process incorporates individually shaped heat-sealing blades, which are machined or likewise manufactured, to actually match the outer profile of the attended object to be shrink-wrapped.

PRIOR ART AND RELATED INFORMATION

It is common in the prior art to use heat-sealing pouches, as in U. S. Pat. No. 6,260,705, which simply cover the proposed article and provide for a sealed end. A bottom seal contour bag manufacture is illustrated in U. S. Pat. No. 3,558,406, which is intended to simply provide a contoured end seal. A bag end is contoured to provide an evenly distributed closure in U. S. Pat. No. 3,053,723.
Shrink-wrap systems are well known in the art. Exemplary thereof are Exlfilm Shrink Film of Montreal, Quebec, Canada and Sarasota, Fla., U.S.A. Automatic heat sealers, heat shrink tunnels and associated equipment are readily available from companies known in the art, such as Clam Seal Corporation, Cleveland, Ohio.

BACKGROUND OF THE INVENTION

The present invention relates to a method and apparatus for heat-sealing thermoplastic film about regular and irregular shaped articles. More particularly the method and apparatus relate to shrink wrap packing processes, which form fit heat sealable plastic films around the profile of regular and irregular shaped articles. This process incorporates individually shaped heat-sealing blades, which are machined or likewise manufactured, to actually match the outer profile of the attended object to be shrink-wrapped.
The apparatus and method of the present invention also contemplates a split-cavity mold design, which also matches the profile of the attended object to be packaged, assists in holding the shrink film in place around the intended packaged object and defines the location of the sealed film sidewall or margin seals.

SUMMARY OF THE INVENTION

The apparatus and method of the present invention contemplates shrink-wrapping a heat sealable thermoplastic film about regular and irregular shaped articles through the provision of initially providing the thermoplastic film above and below the article with margins of the film extending beyond the article to be sealed. In accordance with applicant's invention, one or more heat-sealing blades are generally configured to the article exterior contour to heat-seal the film margin about the article and provide shrinkage about the article. Specifically, the spacing of the heat-sealing blade adjacent areas of the article, are intentionally non-uniform first positions relative positions of the blade, which are more widely spaced in second positions is contemplated. Heating of the blade and contracting the margins to cause film margins contacted by the blade first portions to shrink into contact with and about the article first, and then subsequently film portions contacted by second portions of the blade to shrink into contact and seal about the article second, provide for applicant's novel method and apparatus.
In an exemplary embodiment, an article such as golf club head is provided with a generally right angle, fairly sharp corner for intersection normally between the shaft and club head. By positioning the sealing blade first portions more closely to such corner or irregular shaped areas of the exemplary club head and shaft, a more clean and neat shrink-wrap can be obtained. In a preferred exemplary embodiment, the spacing of blade first portions is one-third closer than other portions to cause film movement to occur first into contact with the irregular shaped article in its irregular position, while second portions associated with the sealing blade are allowed to move secondly into contact with the article in a heat-shrink operation.
In the preferred exemplary embodiment, the article to be enveloped is placed in a bottom half of a mold, which is designed to facilitate positioning margins of the film adjacent the article. A top mold is provided with a hold-down clamp to hold margins of the film in place, while a specifically contoured heat-sealing blade assembly is then brought into contact with the film to cause it to shrink in the desired manner.
In an alternative split-mold construction, upper and lower mold halves are provided with a plurality of heat ports with associated valves to control the heating in different areas of the mold, while the shrink-wrap process is completed. Upper and lower portions of the mold may be provided with heat zones in a further alternative to concentrate heating in particular areas of the article being wrapped, such as in the area where the irregularity, sharp corner, or objectionable configuration is found in the article being wrapped.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a partially exploded view of apparatus employing the method of shrink wrapping a heat sealable thermoplastic film about regular and irregularly shaped articles in accordance with the present invention.
FIG. 2 is a side-section view illustrating apparatus of FIG. 1 in assembled relationship.
FIG. 3 shows a heat sealable thermoplastic film of general rectilinear configuration, which can be positioned above and below the article to be sealed.
FIG. 4 is a sleeve of thermoplastic material, sealed at an upper end and open at lower ends, to fit around an exemplary golf club head.
FIG. 5 illustrates the preferred layout of sealing blade about an exemplary golf head in practicing the method of the apparatus of FIGS. 1 and 2.
FIG. 6 illustrates an interim step in the practice of applicant's method herein.
FIG. 7 illustrates a heat sealable thermoplastic film shrunk evenly about an exemplary golf head in accordance with applicant's method.
FIG. 8 shows applicant's heat-sealing blade apparatus of FIG. 1.
FIG. 9 is a section view of the heat-sealing blade apparatus of FIG. 8.
FIG. 10 shows applicant's mold, top and bottom, having heating ports positioned to provide heating zones of the mold cavity.
FIG. 11 is a plan view of the mold of FIG. 10.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, an exemplary golf club head 10 is illustrated having a shaft 11. Typical golf club heads have an intersection, indicated generally at 12, where the shaft and head come together. It is very desirable to provide a shrinkable thermoplastic film shrink-wrap at such location, which tightly adheres to the golf club head and shaft portions without providing an unsightly billet of excess material. As disclosed hereinafter, applicant's method of shrink wrapping is intended to solve such problem.
A mold bottom 20 is provided, having a top surface 21 and internal supports 22 and 23 for supporting the exemplary golf club head indicated generally at 10. A mold entrance 13 is provided.
As illustrated in FIG. 3, a heat shrinkable thermoplastic film 15 may be provided in a rectangular configuration to ie above, below and essentially around the golf club head generally indicated at 10 in FIGS. 1 and 2. An alternative heat sealable thermoplastic film 16 may also be provided where an upper end 17 is pre-sealed, while lower openings 18, may be provided for fitting film 16 initially about the exemplary head, indicated generally at 10, in FIG. 2.
As seen in FIGS. 1 and 2, clamp 30, having clamp seat 31, may be initially fitted down on surface 21 to seal the exemplary heat sealing thermoplastic film 15 about the exemplary club head. Then, in otherwise known manner, the upper mold 35 may be brought down around the clamp to provide an interior chamber 36, as well as a configured heat sealing assembly 27.
In accordance with the apparatus and method of applicant's present invention, heat sealing assembly 37 includes a heat sealing blade 38 generally configured to the article exterior contour to heat seal 15's margin about the exemplary golf club head, indicated generally at 10, and shrink film 15 about the exemplary golf club head wherein the spacing of the blade 38 adjacent the club head is intentionally non-uniform, first portions of blade 28 being closer to the exemplary golf club head than second portions as will now be explained.
Refering now to FIGS. 8 and 9, it has been found to be particularly desirable to use a flexible cable heating source 39 to provide the contoured heating blade configuration contemplated by the present invention. Exemplary of such flexible heating cables, is the Cable Heater by Watlow, Inc., Columbus, Miss., U.S.A. The range of cable diameter is preferably between 0.068 to 0.0875 diameter. Flexible cable 39, according to the present invention, is preferably provided with a cover cap that fits over the blade 38. Flexible cable 39 is an electrically powered resistor, while blade 38 may be an insulating material.
In a preferred exemplary embodiment, the resistor, cable 39 is made of a metal wire having a high temperature silicon outer coating over a silicon rubber or “Capton”™ polyimide base. Upper blad cover 40 and the blade 38 are preferably made of aluminum and coated with Tefton™.
Hold down guides 41-44, as seen in FIG. 9, are provided to hold the cover 40 over the cable 39 to the blade 38. Guides 41-44 may be made of longitudinally extending springs to provide a mechanical interference that hold the cover 40 to blade 38. Alternative fastener means may be employed by worker, as in the art.
In accordance with the apparatus and method of the present invention, and referring now to FIGS. 5-7, sealing blade 38 is generally configured to the exemplary article, the golf club indicated generally at 10 in the present example, configured to its exterior in a predetermined particular manner. Noting that the exemplary article is of an irregularly non-uniform configuration it is very desirable that the conforming blade 38 be positioned indicated generally at 4 adjacent the sharp edge of the shaft-club arrangement than it is in other areas as indicated generally at 42 and 43.
In a preferred example, blade 38 is positioned adjacent the corner of the exemplary golf club and shaft about one-third of the spacing of blade 38 from second positions as exemplified by the second areas indicated generally at 42 and 43. As heat is applied through blade 38, the thermoplastic film 15 moves inward into engagement at area 141 in the sharp edge or corner of the illustrative golf club indicated generally at 10 and associated shaft 11. Blade 38 is thus heated and placed into contact with margins of film 15 contacted by the first blad portions indicated generally at 41, to shirnk quickly into contact with and about the exemplary article first. Other film portions, as indicated at 43 contacted by the more widely spaced blade 38 configuration, causes such second portions to shrink into contact and seal about the exemplary article second.
On completion of the sealing action, as seen in FIG. 7, a neat seal is effected around the exemplary golf club head or article having an irregularly-shaped intersection, or the like, to provide sealing without excess film webbing in the sharp or corner areas, as indicated at 41. The second portions, indicated generally at 43 by way of example, simply catch up as the thermoplastic film shrinks around the exemplary article to a complete and enveloping condition, but the careful pre-positioning of the flexible blade 38 to be closer in areas where a sharp corner or objectionable irregularity occurs and results in the complete enveloping of the article by the thermoplastic film without there being unwanted excess material, as might be occasioned by heat shrinking of thermoplastic film about such article by other methods using other apparatus.
An exemplary split-mold design is illustrated in FIGS. 10 and 11, in accordance with the method and apparatus of the present invention. Split-mold 50 is provided with a top 51 and bottom 52. A plurality of heating ports 53, 54 are provided in the top and bottom portions of the mold, as are associated control valves 55 and 56. A source of hot air 57 and 58 are each connected to associated plenums 59 and 60, which lead to the plurality of heating ports.
As seen in plan view of FIG. 11, the individual heating ports 53 and 54 of FIG. 10 may be positioned in two zones to provide heat in desirable areas. As seen in FIG. 11, first zones can be provided through grouping of hot air ports, indicated generally at 61 and 62, which are grouped along the side of the exemplary article, golf club 10 in the present example, away from the sharp corner or intersection area to facilitate overall control of sealing of the film about the article. Important second zones indicated, generally at 63 and 64, may be provided in the areas of the sharp or irregularly shaped intersection of the article, golf club head indicated generally at 10 and shaft 11 in the present example, to encourage fluid movement in this area, which in accordance with the present invention is one of the pre-selected areas for moving the material more quickly into contact with the article, to provide a smooth shrink wrap arrangement.
The heating ports 53, 54, as well as the exemplary heating zones indicated generally at 61-64, may be provided at different heating temperatures, or at the same temperature at different times, to facilitate the shrink-wrap procedure of the present invention.
Having thus described a preferred exemplary embodiment of the apparatus and method of the present invention, it should be understood by those skilled in the art that various modifications, adaptations and alternative embodiments thereof, may be made within the scope and spirit of the present invention which is defined by the following claims.

Claims

1. A method of shrink wrapping a heat shrinkable thermoplastic film about regular and irregular shaped articles comprising:

providing said film above and below said article with margins of said film extending beyond said article;

providing one or more heat sealing blade generally configured to the article exterior contour to heat seal said film margin about said article and shrinkage of said film about said article wherein the spacing of said blade adjacent said article is intentionally non-uniform, first portions of said blade being closer to said article than second portions; and

heating said blade and contacting said margins to cause film margins contacted by said blade first portions to shrink into contact with and about said article first and film portions contacted by said second portion to shrink into contact and seal about said article second.

2. The method of claim 1 wherein said article has one or more inwardly shaped corner to be wrapped; and said blade first portions are spaced from said one or more corners a distance of about one-third the spacing of said blade second portions for said article.

3. The method of claim 1 wherein: said film is provided as one piece folded over and under said article.

4. The method of claim 1 wherein: said film is provided as a film pouch fitted about said article.

5. The method of claim 1 comprising: clamping said film about said article before sealing of said margins.

6. The method of claim 1 comprising:

positioning said article in a bottom part of a split mold;

mounting said heat seating blade on an upper part of said mold.

7. The method of claim 6 comprising:

heating interior zones of said mold through heat introducing ports positioned to allow heating of some interior zones of said mold to temperatures which differ from that of other interior zones of said mold.

8. The method of claim 1 comprising: heating said heat one or more sealing blade by an electrically activated flexible cable heater provided within said one or more blade.

9-19. (canceled)

20. A method of shrink wrapping a heat sealable and shrinkable thermoplastic film about an article to be wrapped, said method comprising:

staging a sequence of shrinkage of different parts of said film about said article to cause a first tight fit of said film about preselected parts of said article and a second subsequent tight fit of said film about other parts of said article.

21. The method of claim 20 wherein said staging comprises:

providing a heat sealing blade for sealing and heating of said film to cause shrinkage about said article; and

spacing first portions of said blade closer to said certain pre-selected parts of said article than the spacing of said blade from said other parts of said article.

22. The method of claim 21 wherein:

said spacing of said blade first portions is about one-third of the spacing of said blade from said other parts of said article.

23. The method of claim 20 wherein said article has an irregular shape with angled intersections of adjacent surfaces:

presenting corner or sharply curved intersections, said method comprising:

staging the sequence of shrinkage for said pre-selected parts at said intersections.

24. The method of claim 20 comprising: heating of aid heat sealing blade by an electrically activated flexible cable heater provided within said blade.

25. The method of claim 20 comprising:

staging the sequence of shrinkage of different parts of said film about said article to produce a tighter fit of said film about said preselected parts than the fit of said film about said other parts of said article.

26-55. (canceled)