Sheet metal container making – Method – Forming or treating metallic closure
Reexamination Certificate
2001-04-20
2002-05-14
Newhouse, Nathan J. (Department: 3727)
Sheet metal container making
Method
Forming or treating metallic closure
Reexamination Certificate
active
06386813
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a container lid. More particularly, the present invention pertains to a safe container lid that is positionable on the open end of a container, with the lid being designed so that upon opening the lid at least the central portion of the lid that is separated from the peripheral portion of the lid remaining on the container possesses a safe edge. The present invention also relates to a method of fabricating such a safe container lid.
BACKGROUND OF THE INVENTION
Containers for holding various type of contents include a variety of different lids. One type of container lid that is commonly used in, for example, canned pet foods, includes a tear line that extends around the lid adjacent the rim. These container lids also include an opening tab that is adapted to be lifted up to sever the tear line along a portion of the lid circumference. The opening tab is then pulled upwardly to completely separate and remove the central portion of the container lid from the peripheral portion of the lid that remains on the container.
While these types of container lids are useful from the standpoint of providing easy access to the container interior, they suffer from certain drawbacks and disadvantages. Perhaps the most significant problem with these types of container lids is that they can be somewhat unsafe. Once the central portion of the container lid has been removed from the remaining peripheral portion, an extremely sharp edge exists on the removed central portion of the lid as well as on the peripheral portion of the lid remaining on the container. The sharp edge on the removed central portion of the lid is potentially hazardous to people handling the removed portion and also presents a danger to others if the removed central portion is discarded in the trash without special precautions being taken. Also, the sharp edge on the peripheral portion of the lid remaining on the container presents a potential hazard during removal of the contents from the container, particularly if the contents are consumed directly from the container. It has been found for instance that in the case of containers of relatively shallow depth, it is not uncommon for individuals to use their fingers to try to remove the entire contents from the container. Thus, the potential for individuals to cut themselves on the sharp edges of these types of containers is rather significant.
Various proposals have been made in the past to configure these types of containers in a way that reduces the risk of injury to users and other individuals. One such proposal is set forth in U.S. Pat. No. 5,105,977. This patent describes a lid provided with a tear line and configured so that upon removal of the central portion of the lid from the remaining portion of the lid, a part of the central portion of the lid extends outwardly beyond the sharp edge of the central portion so that the sharp edge is not exposed. Also, a part of the peripheral portion remaining on the container extends beyond the sharp edge on the peripheral portion so that the sharp edge is not exposed. This is achieved by forming folds in the sidewall of the lid on opposite sides of the tear line.
In practice, however, it has been found that this lid construction is susceptible of certain improvements. In one respect, it is oftentimes necessary to apply a coating (e.g., an enamel coating) to the surface of the lid that will eventually serve as the interior surface of the container lid. In the case of lids made according to the patent described above, this coating is typically applied prior to the fabrication steps associated with the formation of the tear line and the folds in the sidewall. In the disclosed method, the tear line is formed by shallow drawing. This shallow drawing formation of the tear line presents several difficulties.
First, the residual material remaining at the tear line after the shallow drawing tends to be somewhat thick and requires an excessively large rupture force to sever the tear line. More importantly, the shallow drawing method of forming the tear line causes the enamel coating to become separated from the lid because the material forming the lid tends to be stretched by virtue of the shallow drawing. This then requires that the coating on the lid be subjected to a repair operation to correct the damaged portion of the coating. The cost and environmental concerns associated with performing such a repair operation do not make it a very viable alternative.
In addition, the way in which the upper fold is formed in the sidewall of the lid makes it extremely difficult to remove process water from the fold. The upper fold is formed by downwardly inclining a portion of the sidewall and so the space underlying this downwardly inclined sidewall portion is quite small. This thus presents the possibility that corrosion will form on the lid and degrade the integrity of the lid. Further, the formation of the downwardly inclined sidewall portion tends to place stress on the score line which can result in fracturing.
Another area in which the lid described in U.S. Pat. No. 5,105,977 is susceptible of improvements involves other difficulties associated with initially severing the tear line when the opening tab is pivoted upwardly and fully opening the container by pulling up on the opening tab. The lid is configured so that there is very little clearance between the tear line and the portion of the lid sidewall lying immediately below the tear line. This means that at the time the opening tab is pivoted upwardly to sever a portion of the tear line, there is only a very small distance through which the severed edge of the removable plate portion can move downwardly before contacting the underlying portion of the sidewall. At that point, further movement of the severed edge of the removable plate portion is restrained by the underlying portion of the sidewall. As a result, only a small portion of the tear line can be severed during the upward pivoting of the opening tab. There is thus a rather large circumferential extent of the tear line that must be severed by the upward pulling of the opening tab to effect complete removal of the central portion of the lid. It has been found that if the circumferential extent of the tear line that must be severed by the upward pulling of the opening tab is too great, it is difficult, if not impossible, to completely open the lid.
A further area in which the lid described in the aforementioned U.S. patent is susceptible of improvements involves the manufacture of the lid. During the fabrication of the lid, the lid needs to be oriented in the rotational sense to ensure that if the lid is rotated a small amount from one station to the next the lid is nevertheless properly positioned for subsequent fabrication operations. The lid also needs to be properly positioned in the radial sense to avoid side-to-side movement of the lid during the fabrication operations. This proper orientation and positioning of the lid becomes even more significant in high speed manufacturing operations.
In light of the foregoing, a need exists for an improved container end closure which, upon opening, presents a safe edge on at least the removable portion of the closure to prevent injury.
A need also exists for an improved container end closure which, upon opening, presents a safe edge on both the removable portion of the closure as well as the portion of the closure remaining on the container.
It would be desirable to provide a safe container end closure that can be relatively easily opened.
It would also be desirable to provide a safe container end closure that is not susceptible to inadvertent removal of the interior coating on the closure during fabrication of the closure.
It would be further desirable to provide a container end closure that is designed to facilitate the removal of process water to prevent corrosion.
A need also exists for a method of manufacturing a safe container end closure that is relatively easily opened and that does not require reworking of the closure a
Douglas Peter M.
Huber William
Burns Doane Swecker & Mathis L.L.P.
H. J. Heinz Company
Newhouse Nathan J.
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