US3437228A

US3437228A - Container structure and manufacture

Info

Publication number: US3437228A
Application number: US495796A
Authority: US
Inventors: William T Saunders
Original assignee: National Steel Corp
Current assignee: National Steel Corp
Priority date: 1965-10-14
Filing date: 1965-10-14
Publication date: 1969-04-08
Anticipated expiration: 1986-04-08

Description

April 8, 1969 w. T. SAUNDERS 3,437,228

CONTAINER STRUCTURE AND MANUFACTURE Filed Oct. 14, 1965 Sheet of a FIG. I

. INVENTOR WILLIAM I SAUNDERS BY gww qw ATTORNEYS April 1969 w. T. SAUNDERS 3,437,228

CONTAINER STRUCTURE AND MANUFACTURE Filed Oct. 14, 1965 v Sheet ors FIG. 6

m x M60 6 FIG. 7

9| 62 iii l INVENTOR WILLIAM T SAUNDERS ATTORNEYS April 8, 1969 w. T. SAUNDERS CONTAINER STRUCTURE AND MANUFACTURE Shet Filed Oct. 14. 1965 R 0 ms MR N U A S .l N M L n w ATTORNEY United States Patent 3,437,228 CONTAINER STRUCTURE AND MANUFACTURE William T. Saunders, Weirton, W. Va., assignor to National Steel Corporation, a corporation of Delaware Filed Oct. 14, 1965, Ser. No. 495,796 Int. Cl. B65d 17/24 US. Cl. 220-54 7 Claims ABSTRACT OF THE DISCLOSURE Process for forming a unitary rivet for an easy-open container without substantially decreasing the thickness gage of metal confronting container contents in which the head portion of a rivet is clamped between a yieldablymounted, spring-loaded pin and a solidly-mounted punch member during formation of the rivet. Easy-open container utilizing a unitary rivet to hold one end of an elongated tab opener to a container. The elongated tab opener has a curvilinear configuration at its secured end for initiating puncture of the container. The container closure has a scoreline which circumscribes and is substantially parallel to such curvilinear configuration of the elongated tab opener. Guide means on the container closure constrain pivotal movement of the elongated tab opener to maintain such parallel relationship.

This invention is concerned with easy-open containers and teaches methods for economical fabrication of readily-openable sheet metal containers.

Containers with opening keys, or other tools, which have to be manipulated into working position are known in the container art. One contribution of the present invention is a new integral opener which is carried in working position on a container. In general, manufacture of integral openers has been limited to soft, lightweight metals such as aluminum. Also uses for integral openers of the prior art have been limited. The integral-opener of the present invention can be fabricated from any of the standard sheet metal container materials, including sheet steel. Further, the integral opener of the present invention can be used economically in any environment including applications having high strength requirements, such as carbonated beverage containers.

The present invention is also concerned with manufacture of a novel lug from container stock sheet metal. This unitary lug is located to permit easy removal of a portion of the container using a separate forktype opener. With the novel methods taught by the present invention this unitary lug can be fabricated economically from any of the standard sheet metal container materials, including sheet steel.

In particular, the present invention teaches methods for processing sheet metal, such as steel strip, to form container closures using simplified steps which can be readily automated for the economic production of high strength, easily openable, and low cost container closures. Mild steel, plated with a protective metal or unplated, can be used in carrying out the invention since the manufacturing process maintains the protection aiforded by platings of tin, aluminum, aluminum-manganese, zinc, and the like, usually applied to steel.

A unique fabrication method is taught which does not substantially diminish the strength or gage of the sheet metal container material. As a result, a light gage steel can be used which makes for easier, more foolproof opening. For example, with the present process a con- 3,437,228 Patented Apr. 8, 1969 ice aluminum. The result is a more economical, more readily openable, hand-operable container closure.

While the invention is applicable to a number of container materials, the specific description to follow will emphasize use of steel plate since it has not been considered commercially feasible in the past to make easy-open container covers for many applications from steel. The specific description will also emphasize manufacture of closures for carbonated beverage containers since the high strength requirements of beer cans, for example, present the greatest obstacles to easy-open features desired in hand opening containers. Overcoming the obstacles in that environment makes it clear that the teachings of the invention can be applied readily throughout the container market.

In the past, tin-plated steel can ends for beer were made of phosphorized steel, temper T-6, of a weight of around 100 to 112 pounds per base box, that is steel with a thickness gage around .011" and higher. With the introduction of lighter gage double-reduced materials for can sidewalls, attempts were made to reduce the endwall weight gage below 100 pounds per base box. However a relatively heavy weight endwall material was necessary in order to make a strong end seam and in order to withstand the pressures of pasteurizing beer without outward buckling of the endwall. Teachings of the present applicant on a reinforced countersunk can end in his copending application, Ser. No. 387,609, filed Sept. 5, 1964, which is included herein by reference, permit beer can ends to be manufactured from much lighter tinplate, for example in the 50 to pound per base box range (around .006) using mild steel.

While the reinforced countersunk method provides greater strength for beer can ends, it is to be understood that the present invention is not limited to reinforced countersunk container closures but is applicable as well to other embodiments including two-piece containers using a drawn body in which the opener is part of either the body or the closure means. However, the reinforced countersunk method makes possible tinplate beer can ends of a weight less than 75 pounds per base box which greatly reduces the force required to open such a container. Also the steel can be universal-temper (TU) mild steel plate without additives as required for phosphorized or renitrogenized steel. By mild steel is meant the conventional steel used in making blackplate, tinplate, and the like having a carbon content up to about fifteen points (015% C.); in brief, one of the conventionally produced steels without costly additives can be used to fabricate products taught by the present invention.

The invention teaches formation of a rivet for holding an integral tab opener to container plate in which the rivet is unitary with the plate. That is, the rivet is formed from metal in the plate. The invention also teaches formation of a flanged lug which is unitary with sheet metal container plate. The important contribution in these teachings is that fabrication of a unitary rivet or a unitary lug takes place without substantially decreasing the thickness gage of the head portions of those unitary structures which confront the material in the container.

Also, because of a number of unique features in the integral tab opener, its securing means, and coordinated operational features between these and the area to be removed from a container cover, the manufacturing process taught for manufacture of an integral tab opener container can be straight-forward and sequential without the problem of individual steps in the manufacturing process doing damage to or impeding work performed in other steps.

The accompanying drawings will be referred to for a more detailed and specific description of the above and 3 other unique features of the invention. In these drawings FIGURES 1 through 4 illustrate steps in formation of a protrusion and a reinforced countersunk rim in a sheet metal blank,

FIGURE 5 is a sectional view of a portion of the sheet metal blank of FIGURE 4 with a tab-opener removably held on the blank.

FIGURE 6 illustrates steps in the formation of a unitary rivet,

FIGURE 7 illustrates a completed unitary rivet securing the tab opener to the sheet metal blank,

FIGURE 8 is a top plan view of a container closure embodying the invention,

FIGURE 9 is a sectional view along the line 9-9 of FIGURE 8,

FIGURE 10 is a top plan view of a full open container embodying the invention,

FIGURE 11 illustrates steps in the formation of a unitary lug, and

FIGURE 12 illustrates a completed unitary lug.

Referring to FIGURES 1 through 4, stages are shown in the formation of a protrusion in sheet metal by drawing of the sheet metal along with simultaneous formation of a reinforced countersunk periphery. The drawing steps gather sufficient metal for formation of a unitary rivet with little significant change in the gage of the metal forming the protrusion.

Referring to FIGURE 1 in particular, a button 15 is formed in blank 16 with the button 15 protruding from the bottom surface of the blank and forming a depression in the top surface of the blank. It will be noted that the button 15 is shallow in depth and large in diameter. This configuration permits sufficient metal to be drawn into the button to enable formation of a unitary rivet without harmful reduction of thickness gage. At the periphery of blank 16 a countersunk rib 18 is formed.

In FIGURE 2-, folding over of the countersunk rib 18 is shown at 22 and button 15 of FIGURE 1 is inverted to form protrusion 24 from the top surface of the blank 16. It will be noted that the protrusion 24 has an increased depth and reduced diameter in relation to the button 15 of FIGURE 1. This working of the metal is accomplished without substantially reducing the thickness of metal drawn in button 15; in practice the thickness of the metal in the button 15 is within one thousandth of an inch of the thickness of the metal in the remainder of the sheet metal blank.

In the third step shown in FIGURE 3, a hem 26' is formed at the periphery of blank 16. A protrusion 28 of increased depth and decreased diameter with respect to the protrusion 24 of FIGURE 2 is formed by movement of the metal already drawn into protrusion 24.

In step four, shown in FIGURE 4, the protrusion 30 is formed from metal in the protrusion 28 of FIGURE 3. This protrusion from the top surface of the blank is substantially cylindrical in a cross-sectional plane which is parallel to the sheet metal blank. Endwall 32 closes one end of the protrusion and longitudinal axis 34 is substantially perpendicular to the plane of the blank. Sidewall 36 extends substantially perpendicularly between endwall 32 and the plane of the blank and defines opening 40 in the bottom surface of the sheet metal blank. At the periphery of blank 16, folds 42. are formed from the metal in hem 26 of FIGURE 3.

FIGURES shows a typical cross-sectional configuration of a protrusion before formation of a rivet. Protrusion 30 includes endwall and sidewall 46. A tab opener 52 is formed with rounded edges curled under as shown at 54 and depressed ledge configuration 55 around aperture 56 formed in tht tab opener. Ledge 55 rests on panel 50 of the sheet metal blank. The cross-sectional configuration of protrusion 30 can also be fi'usto-conical if desired. Endwall 45 as shown is slightly convex, but can be planar, or concave as well.

Tab opener 52 is removably held on the protrusion 30 by aperture 56 being placed over the protrusion. The next steps in formation of the unitary rivet are important for maintaining required strength and thickness gage properties. Prior art integral openers formed from aluminum sheet metal, for example, require relatively heavy gage sheet metal, around .0145" in thickness, due in part to the prior art method of forming unitary rivets. In the prior art, a tab opener was secured to a container by forcing metal in the rivet head to overlap the tab opener. This caused a 60 to reduction in thickness gage of the metal in the rivet head. As a result the rivet head, which faced the container contents, was often less than .006" in thickness while the remainder of the container cover, from which metal had to be torn to make an opening was a heavy 10145 in thickness. By following the steps of the present invention a unitary rivet is formed without decreasing the thickness gage of the sheet metal in the rivet head facing the container contents; therefore the entire container end from which the protrusion is formed can be of a lighter gage.

Formation of a unitary rivet in accordance with the teachings of the invention is shown in FIGURES 6 and 7. Endwall 45 of protrusion 30 is clamped between a yieldably-mounted, spring-loaded movable pin 58 and a solid mounted punch 60. The panel 50 of the sheet metal closure is supported contiguous to protrusion 30 on solid support die 62. By clamping metal in the endwall 45 between spring loaded pin 58 and solid mounted punch 60 its thickness does not change during formation of a rivet. Sidewall 46 is prevented from moving inwardly by spring loaded pin 58. The sidewall moves outwardly as shown in dotted lines in FIGURE 6. Spring-loaded pin 58 moves downwardly as the protrusion 30 is collapsed.

As shown in FIGURE 7, end-wall 45 becomes the head of the unitary rivet formed and sidewall 46 overlaps aperture 56 holding tab opener 42 to panel 50. In this Way a structurally strong rivet is formed and metal in the rivet head, which faces the container contents and therefore must withstand container pressures, is not reduced in thickness during formation of the rivet. With this method the entire metal blank from which the unitary rivet is formed can be substantially thinner than that required by prior art methods. As a result the container is easier to open and more economical to manufacture.

FIGURE 8 shows a container closure- 64 with tab opener 52 held to panel 50 by unitary rivet 66. Scoreline 68 defines an area 69 to be removed by lifting tab opener 52. Pivotal movement of tab opener '52 about rivet 66 in the plane of the sheet metal is constrained by raised guides 70. Constraining pivotal movement of tab opener 52 is important to proper puncturing of the panel 50. Puncturing of panel 50 is facilitated by establishing a substantially parallel relationship between tab end 71 and scoreline 68 Within the sector designated 72. By constraining pivotal movement of tab opener 52 the substantially parallel relationship between end 71 and the scoreline is maintained even though the tab opener 52 may be turned slightly for purposes of raising free end 74 of the tab opener 52, as will be described later. As a result of the above described parallel relationship the opening force of tab opener 52 is concentrated most effectively along that portion of scoreline 68 where initial puncture will occur When opening a container, tab opener 52 acts as a Class 1 lever with its fulcrum at rivet 66, its output or working end at 71, and its input end at 74. Referring to FIGURES 8 and 9, by lifting tab end 74 a lever action, with mechanical advantage dependent on the relative lengths of the input and output arms on either side of the fulcrum (rivet 66), concentrates a depressing force at end 71 along the parallel portion of the scoreline 68 'within sector 72. Guides 70 by constraining pivotal movement of tab opener 52 maintain the proper parallel relationship and concentration of downward force of the tab opener along the portion of screenline 68 within sector 72.

The downward force at end 71 of tab opener 50 is implemented for purposes of initial opening of a container by a lifting force at the end of the rivet 66 closest end 74. This lifting force places the metal at the scoreline within sector 72 under tension.

The configuration of scoreline 68 is also important at the end opposite to sector 72. After lifting tab opener 52 to puncture panel 50, tab opener 52 is pulled backwardly toward the periphery of the can for removal of defined area 69. The metal tears along the scorelines between guides 70. The scoreline terminates in a blunt end having corners of differing radii of curvature. The larger radius of curvature 76 causes the metal to tear along that part of the scoreline first so that the metal being torn converges on a smaller radius of curvature 77. As a result the metal to be broken for final removal of defined area 69 is reduced to the small radius of curvature of 77.

With the tab opener 52 secured to the panel 50 and positioned as shown in FIGURE 8, the opener is recessed with relation to the top of the peripheral edge of container cover 64 so that the container will not inadvertently catch on objects during handling or packing. The tab opener 52 can be operated in this position, however the invention makes provision for raising end 74 to facilitate opening. Referring to FIGURES and 9 it will be seen that the edges of tab opener 52 are rounded and include sheet metal which projects downwardly toward panel 50. A raised ridge 91 is provided on panel 50 within the defined area 69. Ridge 91 is positioned near rivet 66. By pivoting tab opener 52 slightly, a downwardly projecting edge of tab opener 52 rides up on ridge 91 raising end 74. Raised guides 70 constrain pivotal movement so that the substantially parallel relationship between end 71 and a portion of scoreline 68 within sector 72 is maintained notwithstanding the slight pivoting for purposes of raising tab end 74. It will be obvious that ridge 91 can also be used to constrain pivotal movement of tab opener 52.

Tab opener 52 also includes indention 92 at a turned-up portion of the handle near end 74. This indention facilitates gripping of the handle during the pulling step in opening a container.

The above teachings provide a readily openable, hand operable device. Instructions for opening a container can be simplified as follows: turn, lift, and pull.

A specific embodiment of the present invention using tin-plated steel for beer cans would have a panel thickness in the range of .005 to .0075", and residual metal at the scoreline of .002".

The teachings of the present invention are also applicable to a full open container. An embodiment of a full open container cover is shown in FIGURE 10. Rivet 80 is placed off-center with respect to container cover 82, however other features described above remain substantially the same, including a parallel relationship at the secured end of the tab opener between tab opener 84 and scoreline 86. It will be noted that the tab opener 84 is positioned entirely within the scoreline so that the blank can be scored afer attaching the tab opener. Scoreline 86 after circumscribing tab opener 84 narrows considerably in approaching the periphery of container cover 82 and proceeds circumferentially around the periphery to approach and terminate contiguous to the scoreline circumscribing the tab opener. Raised guide portion 88 is extended around the container cover to prevent upward bending of the panel or a portion of the panel during tearing of the metal.

There are many applications for easy-open containers where the integral ta b type opener is not completely suitable; for example, in vending machines of hot products and at commercial establishments which would require a person to hand open numerous containers. The unitary lug, easy-open container, as described in copending application entitled Container Lug by Marvin S. Young, filed concurrently with the present application and assigned to the same assignee, is especially adapted to such uses. The unitary lug, however, presents difiiculties in fabrication, especially when working with steel, which are solved by the present invention.

Referring to FIGURE 11, protrusion 90 is formed in a sheet metal blank by a series of steps similar to those described in relation to FIGURES 1-4 used in forming a protrusion for a unitary rivet. In general, the unitary lugprotrusion will be longer and sometimes larger than a unitary rivet protrusion so that more metal should b drawn in the formation steps in order to avoid harmful reduction of thickness of the metal.

Protrusion 90 includes a closed endwall 92 and a cylindrically shaped sidewall 94 spaced radially from longitudinal axis 96 of the protrusion.

The present invention teaches a method of forming a flanged unitary lug in which the closed endwall 92, forming the head of the lug is not reduced in thickness during formation of the flange. By forming a flanged lug without reducing the thickness of the head of the lug, which must withstand pressures of container materials, the entire sheet metal blank can be of lighter gage.

In order to accomplish this result, endwall 92 is clamped between power punch 98 and yieldably mounted pin 99. Sheet metal portion 102, adjacent to and surrounding protrusion 90, is rigidly supported by fixed support die 104. Yieldably mounted pin 99 will move a predetermined distance out of the aperture formed by protrusion 90 and will then be rigidly supported.

Force is applied on endwall 92, in a downward direction as indicated, by punch 98. Pin 99 within the protrusion prevents an inward collapse of the sidewall of the protrusion, collapsing the sidewall is initiated at the rounded portion at the top edge of protrusion 90, and a portion 106 of the sidewall flares outwardly forming a shoulder as endwall 92 is moved downwardly. No outside support die is necessary for the sidewall since the somewhat beveled edge where the sidewall joins the remainder of the sheet metal blank prevents outward collapse in this region and the rounded configuration at the top of protrusion 90 initiates the flare out of the sidewall. After pin 99 moves a predetermined distance out of the aperture as indicated in FIGURE 11, it is rigidly supported, and sidewall portion 106 forms a projecting shoulder or flange on unitary lug 108 as shown in FIGURE 12.

The pin means 99 determines the spacing between flange 106 and adjacent portions of the sheet metal 102; this will ordinarily be between and for a beverage container. The flange will ordinarily extend radially outwardly about beyond the circumference of sidewall 94. The sheet metal is scored as indicated at 110.

By insertion of a pronged pull-type opener between 106 and 102 with a prong on opposite sides of the lug, and by applying an upward force, the scored portion of the sheet blank is torn from the container. The size of the lug may vary with the size of the container being opened and the amount of flange and spacing between the flange and the sheet metal container can be determined by the predetermined movement of pin 99.

While several embodiments of the present invention have been shown and described above, it is understood that modifications and substitutions can be made without departing from the principles of the present invention. Therefore it is understood that the scope of the present invention is to be determined by the appended claims.

What is claimed is:

1. Hand openable sheet metal container comprising elongated tab opener means secured at one longitudinal end to one surface of a sheet metal container by unitary rivet means formed from sheet metal of the container,

a scoreline of diminished metal thickness in the sheet metal container defining an area to be removed from the container by lifting the tab opener means, the scoreline circumscribing the tab opener means at the longitudinal end of the tab opener means secured to the sheet metal container, with such longitudinal end of the tab opener means being aligned with and contiguous to the scoreline such that a lifting force at the remaining longitudinal end of the tab opener means causes puncture of the container along the aligned portion of the scoreline,

means for constraining pivoting of the tab opener means about the unitary rivet means in a plane substantially parallel to the one surface of the container so as to maintain the aligned relationship between the end of the tab opener means secured to the sheet metal container and the circumscribing scoreline at such end of the tab opener means.

2. The structure of claim 1 in which the one surface of the sheet metal container is an end wall.

3. The structure of claim 1 in which the elongated tab opener means lies completely within the scoreline defining an area to be removed from the sheet metal container.

4. The structure of claim 1 in which the means for constraining pivotal movement of the tab opener means comprises raised guide means projecting from the one surface of the sheet metal container.

5. Hand-openable sheet metal container cover comprising elongated tab opener means secured at one longitudinal end to one surface of a sheet metal container cover by unitary rivet means formed from sheet metal of the container cover, the elongated tab opener means having a curvilinear configuration at the end secured to the sheet metal container cover,

a scoreline of diminished metal thickness in the sheet metal container cover defining an area to be removed from the cover by lifting the elongated tab means, the scoreline circumscribing and being in substantially parallel relationship to a projection of the curvilinear configuration at the end of the elongated tab means secured to the sheet metal cover, and

raised guide means projecting from the one surface of the sheet metal cover for constraining pivotal movement of the elongated tab means about the unitary rivet means and maintaining the substantial parallel relationship between the curvilinear end of the elongated tab means and the circumscribing scoreline at the end of the elongated tab means secured to the container cover.

6. The container cover of claim 5 in which the scoreline terminates in a blunt end in spaced relationship from the curvilinear end, with the blunt end having corner portions of differing radii of curvature.

7. Hand-openable metallic container structure comprising a sheet metal blank,

a unitary rivet formed in the sheet metal blank to extend from one surface of the sheet metal blank,

an elongated tab opener means secured at one longitudinal end to the sheet metal blank by the unitary rivet, the elongated tab opener means having a curvilinear edge at its end secured to the sheet metal blank,

a scoreline of diminished metal thickness in the sheet metal blank defining an area to be removed by the elongated tab opener means, the scoreline circumscribing a perpendicular projection on the sheet metal blank of the elongated tab opener means at its secured end and being contiguous with and substantially parallel to at least a portion of the curvilinear edge of the elongated tab opener means at its secured end, and

a raised portion of sheet metal projecting from the one surface of the sheet metal blank for constraining pivotal movement of the elongated tab means to maintain the substantially parallel relationship of the curvilinear portion of the elongated tab opener means with the scoreline at the secured end of the elongated tab means; the elongated tab means constituting a Class 1 lever for removing the area defined by the scoreline with the unitary rivet acting as a fulcrum for the elongated tab opener means so that the portion of the curvilinear edge of the elongated tab opener means is forced downwardly to break sheet metal at the contiguous substantially parallel scoreline by lifting action at the remaining end of the elongated tab opener means longitudinally opposite to its secured end.

References Cited UNITED STATES PATENTS THERON E. CONDON, Primary Examiner.

G. T. HALL, Assistant Examiner.