Patent Application
20150375895
The present disclosure relates to containers in general, and more particularly to containers that are closed by a metal end seamed onto the container body.
For many years the standard technique for attaching a metal end to a metal container body has been the double-seaming method, in which a curled outer edge of the metal end and a flange formed on the container body are rolled up together to form a hermetic seam. The double-seaming technique essentially entails mechanically locking together the metal end and the container body flange. Double-seaming works well for metal container bodies because the metal is ductile and permanently deformable without compromising the integrity of the seam, but encounters difficulties when the container body is plastic or composite because of the relative lack of ductility and lack of permanent deformability of such materials.
The present disclosure relates to an alternative to the traditional double-seaming approach for attaching metal ends to containers. The metal end and the method described herein for affixing the metal end to a container body are suitable for container bodies of various materials including metal, plastic, and composite paperboard/plastic or paperboard/foil/plastic materials.
In accordance with one embodiment, a container assembly comprises a container body formed by a side wall having an upper edge, and a top metal end for affixing to the upper edge of the side wall. The metal end is formed of a shaped metal sheet that has a peripheral edge. The sheet is shaped prior to being applied to the container body such that the outer peripheral region of the sheet includes an inner chuck wall that extends upwardly to a top rim of the metal end, the top rim comprising an outwardly curled, downwardly facing upper U-shaped section. The outer peripheral region of the metal sheet is further shaped to include a skirt extending downwardly from the top rim, a lower end portion of the skirt being formed as an inwardly curled, upwardly facing lower U-shaped section, and an outer chuck wall extending upwardly from the lower U-shaped section, the peripheral edge of the metal sheet defining a top edge of the outer chuck wall. The outer chuck wall is radially spaced from the inner chuck wall so as to define an annular channel therebetween configured to allow the top metal end to be pushed onto the upper edge of the side wall such that the upper edge is received into the annular channel. A heat-sealable material is disposed on at least one of the opposing surfaces of the inner and outer chuck walls.
The metal end is sealed to the container body not by a purely mechanical locking together of the metal end and container body as in conventional double-seaming, but instead by thermal fusion of the heat-sealable material provided on the inner and/or outer surfaces of the side wall and on the opposing surfaces of the inner and/or outer chuck walls. Indeed, the step of pushing the metal end onto the container body to insert the upper edge of the side wall into the annular channel does not require or involve any significant deformation of the metal end or of the container body side wall. Consequently, the material of the container body and its mechanical properties are not of particular importance to the proper attachment of the metal end, and hence the approach is suitable for container bodies of virtually any material as long as a heat-sealable material can bond to the container body with sufficient strength.
Metal ends can be affixed in this manner to both top and bottom ends of a generally tubular container body (for example, a composite paperboard/plastic or paperboard/foil/plastic can), if desired. The approach is also useful for container bodies such as blow-molded plastic cans that require only a single metal end for closing the top opening.
The metal ends can be formed to allow containers to be stacked.
The heat-sealing of the metal end onto the container body can be accomplished in various ways, including but not limited to induction heating of the metal end to melt and fuse the heat-sealable materials together.
Having thus described the disclosure in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present invention now will be described more fully hereinafter with reference to the accompanying drawings in which some but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
A container assembly 10 in accordance with a first embodiment of the invention is shown in
The side wall 14 can be formed of various materials, including metal, plastic, or composite materials. By “composite” material is meant a multi-ply structure formed as a laminate of two or more layers of different materials, typically including at least one paperboard layer and at least one additional layer that can comprise metal foil such as aluminum foil or a plastic layer such as plastic film or a polymer coating. Often, composite containers include paperboard, foil, and plastic layers. For example, a typical composite container as illustrated in
The radially innermost surface of the side wall 14 has a layer 26 of heat-sealable material covering at least the part of the side wall adjacent the upper edge 16. In the embodiment shown in
The radially outermost surface of the side wall 14 likewise has a layer 28 of heat-sealable material covering at least the part of the side wall adjacent the upper edge 16. The heat-sealable layer 28 can be localized to the region adjacent the upper edge 16 or can cover the entire outer surface of the side wall (e.g., the layer 28 could be an outer layer of the label ply 24 provided for sealing edges of the label ply together to form a joint or seam for the label). A localized heat-sealable layer 28 is shown in
When the side wall 14 is not a composite material as described above, the heat-sealable materials 26, 28 nevertheless are provided on the inner and outer surfaces at least adjacent the upper edge 16. For example, if the side wall is metal, then a coating of heat-sealable material can be provided on each of the inner and outer surfaces. The coating on the inner surface can serve to protect the container contents from direct contact with the metal. If the side wall is plastic (e.g., when the container body is a blow-molded plastic container), the side wall material itself can comprise a heat-sealable material such as polypropylene or polyethylene.
The metal end 30 is formed of a blank of metal sheet 32. The metal sheet can have a thickness ranging from about 0.0055″ to about 0.0110″. The sheet is stamped or cut out to have a plan shape generally corresponding to the cross-sectional shape of the container body side wall at the upper edge 16. Thus, if the upper edge 16 has a circular shape then the blank is circular, if the upper edge is rectangular then the blank is rectangular, etc. The metal sheet 32 has an outer peripheral edge 34. The region of the metal sheet adjacent the outer edge 34 is deformed by suitable tool and die operations to have a configuration enabling the metal end 30 to be affixed to the side wall 14 in a manner described below.
More particularly, the outer peripheral region of the metal sheet 32 is shaped to be annular (i.e., to encircle the central axis about which the side wall 14 extends, and to have a substantially uniform cross-sectional shape about the annulus). The annular shape of this peripheral region substantially matches that of the side wall 14 of the container body at the upper edge 16. The peripheral region of the metal end 30 is shaped to include an inner chuck wall 36 that extends generally upwardly from the main central panel 38 of the metal end. The inner chuck wall can include a substantially linear upper portion 40 that is relatively closer to vertical (i.e., closer to being parallel to the central axis) but that can be somewhat inclined relative to vertical as shown in
The outer peripheral region of the metal sheet 32 is further shaped to include a skirt 46 that depends from the top rim 44 and that extends downwardly approximately parallel to the upper portion 40 of the inner chuck wall 36 and is spaced radially outwardly therefrom. The skirt in the embodiment of
The lowermost or third portion 52 of the skirt joins with a lower generally U-shaped section 54 that faces generally upwardly. An outer chuck wall 56 extends upwardly from the lower U-shaped section 54 and is spaced from the inner chuck wall 36 (and specifically the upper portion 40 thereof). The lower end of the outer chuck wall 56 is at approximately the same vertical level as the lower end of the inner chuck wall portion 40 where the metal sheet bends to extend radially inwardly and downwardly along the lower portion 42 of the inner chuck wall. The outer chuck wall terminates at an upper edge defined by the edge 34 of the metal sheet that forms the metal end. The upper edge of the outer chuck wall is spaced below the second portion 50 of the skirt 46 in the illustrated embodiment, although it is possible for the upper edge of the outer chuck wall to contact the lower surface of the skirt if desired.
An annular channel 58 is defined between the inner and outer chuck walls. The channel 58 has an annular shape generally matching that of the upper edge 16 of the side wall 14 of the container body. The channel 58 has a radial width selected with regard to the thickness of the side wall at the upper edge 16 such that the side wall can be inserted into the channel with a close fit as shown in
A layer of heat-sealable material 60 is disposed on at least the portion of the outer surface of the inner chuck wall 36 that contacts the inner heat-sealable material 26 on the inner surface of the container body side wall 14. If desired, the heat-sealable layer 60 can cover the entire lower surface of the metal end as shown, which is advantageous for preventing the contents of the container from directly contacting the metal; alternatively, the heat-sealable layer 60 could be localized to the portion of the inner chuck wall's outer surface that contacts the container body side wall, and another coating (e.g., lacquer) could be employed for protecting against metal contact.
At least the portion of the inner surface of the outer chuck wall 56 that contacts the side wall 14 has a layer of heat-sealable material 62 disposed thereon. If desired, the heat-sealable layer 62 can cover the entire upper surface of the metal end as shown.
Once the metal end 30 is pushed onto the container body side wall 14 to insert the side wall into the channel 58 as shown in
The heat-sealable layers 26, 28, 60, 62 can comprise any of various heat-sealable materials, including but not limited to polyethylene, polypropylene, ionomers such as SURLYN® (ethylene acrylic acid copolymer having acid groups partially neutralized with sodium ions), and the like. The heat-sealable material on the metal end 30 can be, but need not be, identical to the heat-sealable material on the container body side wall 14, the important consideration being that if different heat-sealable materials are employed, the melting point temperatures of the materials should not be too greatly different.
The present invention is subject to numerous variations and embodiments. In the embodiment of
The bottom metal end 30′ also has an outer skirt 46′ that extends upwardly from the bottom rim 44′ to an upper U-shaped section 54′ that faces downwardly, and an outer chuck wall 56′ extends downwardly from the upper U-shaped section and is spaced from the inner chuck wall portion 40′. An annular channel 58′ is defined between the chuck walls 40′ and 56′ for receiving the side wall 14′ of the second container body, the metal end 30′ being heat-sealed onto the side wall in the manner previously described.
It will be recognized that the embodiment having a top metal end 30 and a bottom metal end 30′ as shown in
It is also possible to configure the metal end such that there is no stacking feature. Such an embodiment is shown in
In the embodiments described above, the metal sheet is shaped into its ultimate form prior to being applied to the container body. Thus, the metal end has the skirt, lower U-shaped section, and outer chuck wall already formed in their ultimate configurations before the metal end is pushed onto the container body. Application of the metal end to the container body does not require any specialized tooling for making a double seam, and the difficulties of forming a double seam are avoided.
The embodiments described above and illustrated in the drawings have heat-sealable material layers 26 and 28 on both the inner and outer surfaces of the container body side wall 14, and correspondingly both chuck walls 36, 56 have heat-sealable layers 60, 62 thereon such that two heat seals are formed. However, it is within the scope of the invention to omit one of the heat seals. For example, the heat-sealable layers 26 and 60 can be omitted, such that only one heat seal is formed between the layers 28 and 62 on the outer surface of the container body side wall and the outer chuck wall. Alternatively, the heat-sealable layers 28 and 62 can be omitted, such that only one heat seal is formed between the layers 26 and 60 on the inner surface of the container body side wall and the inner chuck wall.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
This application is a continuation of U.S. application Ser. No. 12/607,731, filed on Oct. 28, 2009, which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12607731 | Oct 2009 | US |
| Child | 14846250 | US |
