Patent Application
20080066290
a) through 9(g) are a series of diagrammatical depictions of a cross-section of the end panel showing seven forming operations in a preferred method of forming an easy open can end according to a preferred embodiment of the invention; and
Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular to
Full open convenience closure 50 further includes a circumferentially extending end curl 58 that is constructed and arranged to be secured to a container using the double seaming process. It also includes a tab 60 that has a main body portion 62 including a nose portion 63 that is constructed and arranged to exert a downward force on the end panel 52 in area that is proximate to the peripheral score 72 when a lifting ring 64 of the tab 60 is lifted by a consumer. A rivet formation 66 secures the tab 60 to the end panel 52. Convenience closure 50 further preferably includes a double fold 68 that is defined in the end panel 52 adjacent to the peripheral score 72 in order to provide cut protection for the consumer.
According to one particularly advantageous feature of the invention, a plurality of opening scores 70 are preferably defined in the end panel 52 in an area that is generally proximate to the location of the rivet formation 66. The opening scores 70 preferably include a mustache score 78, a flex line score 80 and a pair of break line scores 98, 100, which are best shown in
Mustache score 78 further preferably includes first and second end portions 86, 88 that are preferably symmetric with respect to each other about a diametric axis of symmetry 82 that extends through the center 90 of the rivet formation 66. Each of the first and second end portions 86, 88 preferably includes a convex side of curvature that faces the nearest portions of the peripheral score 72. Each of the first and second end portions 86, 88 preferably have a constant radius of curvature R1 that preferably extends along an arc section that is at least about 150°. The constant radius of curvature R1 is preferably substantially within a range of about 0.07 inches to about 0.2 inches.
The distal ends of the first and second end portions 86, 88 in the preferred embodiment point away from the nearest portion of the peripheral score 72, and a tangent line extending through the distal ends would preferably be substantially perpendicular to a tangent line of the peripheral score 72 at a location where the first tangent line would intersect the peripheral score 72.
Preferably, a transition location 92 between the central portion 84 and the first and portion 86 is located at a transitional angle α from the diametric axis of symmetry 82 that is preferably substantially within a range of about 45° to about 60°. More preferably, this angle is substantially within a range of about 50° to about 55°.
The flex line score 80 preferably has a first portion 94 that is located on a first side of the rivet formation 66 and a second portion 96 that is located on a second, opposite side of the rivet formation 66. The first and second portions 94, 96 of the flex line score 80 are preferably aligned and symmetric with respect to each other. The flex line score 80 and its components 94, 96 are preferably substantially perpendicular with respect to the diametric axis of symmetry 82.
The flex line score 80 preferably has a residual thickness (i.e., a thickness that remains in the end panel 52 at the location of the score line 80) that is substantially the same as a residual thickness of the mustache score 78. The flex line score 80 further preferably has a residual thickness that is within a range of about 25% to about 40% of a thickness of the end panel 52. More preferably, the flex line score 80 has a residual thickness that is substantially within a range of about 30% to about 35% of the thickness of the end panel 52. The mustache score 78 has a residual thickness that is preferably substantially within a range of about 25% to about 40% of the thickness of the end panel 52. More preferably, the mustache score 78 has a residual thickness that is substantially within a range of about 30% to about 35% of the thickness of the end panel 52. The mustache score 78 preferably has a residual thickness that is no greater than about 0.0045 inches, and more preferably no greater than about 0.0035 inches.
As
In the preferred embodiment of the invention, a pair of break line scores 98, 100 are defined in the end panel 52 in order to provide a pre-weakened tearing path between the mustache score 78 and the flex line score 80 that is utilized by the convenience closure 50 during the preliminary stages of opening. The break line scores 98, 100 are positioned between the mustache score 78 and the flex line score 80. Each of the break line scores 98, 100 are preferably substantially perpendicular to the flex line score 80 and are aligned with the locations on the respective first and second end portions 86, 88 of the mustache score 78 that most closely approach the flex line score 80. The break line scores 98, 100 are preferably substantially perpendicular with respect to tangent lines that would pass through the locations on the respective first and second end portions 86, 88 of the mustache score 78 that most closely approach the flex line score 80. The break line scores 98, 100 preferably have a residual thickness that is greater than a residual thickness of the flex score line 80 and that is greater than a residual thickness of the mustache score 78. The residual thickness of the break line scores 98, 100 is preferably substantially within a range of about 30% to about 95% of the thickness of the end panel 52, with a more preferred range of about 50% to about 80% of the thickness of the end panel 52.
When the convenience closure 50 is used in conjunction with a can body to package contents under high pressure (i.e. over 20 psi), it may be opened by a consumer by gripping the lifting tab and pulling the lift ring 64 upwardly. As the gripping tab 60 pivots about the rivet formation 66, the nose portion 63 will move downwardly and exert a downward force on the end panel 52 at or near the peripheral score 72. Before the end panel 52 is bent downwardly enough to initiate rupture of the peripheral score 74, however, sufficient tension is formed in the end panel 52 in the area near the central portion 84 of the mustache score 78 to cause a rupture of the end panel at the central portion 84. Pressurized gas within the container will be permitted to harmlessly vent through the rupture in the central portion 84 of the mustache score 78 without affecting the integrity of the peripheral score 72 or accelerating the opening process. The flow of pressurized gas will tend to be directed harmlessly at an oblique angle beneath the fingers of the consumer across the top of the end panel 52 so as not to present a hazard to the consumer.
The presence of the flex score line 80 reduces the amount of force that will need to be exerted by the consumer to cause the initial rupture of the central portion 84 of the mustache score 78.
After the convenience closure 50 has vented, the consumer will continue to pull the lifting ring 64 upwardly, which causes the tear or rupture in the central portion 84 of the mustache score 78 to enlarge. The tearing will progressively advance into the first and second end portions 86, 88 of the mustache score. At the location on the first and second end portions 86, 88 that are closest to the flex line score, the tear line will leave the mustache score and advance directly to the respective first and second portions 94, 96 of the flex line score 80 along the path of the break line scores 98, 100. This will occur even in embodiments of the invention where the break line scores 98, 100 are not present. The tearing will then move laterally outwardly along the respective first and second portions 94, 96 of the flex line score 80. As this occurs, sufficient downward force will be exerted by the nose portion 63 of gripping tab to rupture the peripheral score 74. This stage of opening is shown in the photograph that is provided as
Referring now to
A method of making such a convenience closure 50 according to the preferred embodiment of the invention would include a step of providing an end panel blank and providing the tooling discussed above in relation to
The preferred method of making the convenience closure 50 utilizes a seven operation manufacturing process. A cross-sectional view of the end panel after each operation is shown diagrammatically in
The first forming operation shown in
The second forming operation, shown in
The third forming operation, shown in
The fourth operation, shown in
The fifth operation, shown in
The sixth operation, shown in
The seventh and final operation, shown in
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
