Can end with retort resistant panel, and tooling and associated method for providing same

A can end is provided, which includes a recessed panel defined by an upwardly extending chuck wall. The panel has a product side and a public side disposed opposite the product side. A peripheral scoreline is disposed in the public side of the panel proximate to the base of the chuck wall. A tab is fastened to the panel by a rivet. The tab is operable to sever the peripheral scoreline and open the can end. An pressure resistance bead extends around the panel inboard of the peripheral scoreline and outboard of the rivet. A saw tooth panel formation disposed proximate to the pressure resistance bead inboard of the pressure resistance bead. Among other benefits, the pressure resistance bead and saw tooth panel formation combine to resist wrinkling or other undesired deformation of the can end. Tooling and a method of making the can end are also disclosed.

BACKGROUND

The disclosed concept relates generally to containers and, more particularly, to can ends having retort resistant end panels. The disclosed concept also relates to tooling and associated methods for providing such can ends.

2. Background Information

Metallic containers (e.g., cans) for holding products such as, for example, food and beverages, are typically provided with an easy open can end on which a pull tab is attached (e.g., without limitation, riveted) to a tear strip or severable panel. The severable panel is defined by a scoreline in the exterior surface (e.g., public side) of the can end. The pull tab is structured to be lifted and/or pulled to sever the scoreline and deflect and/or remove the severable panel, thereby creating an opening for dispensing the contents of the can.

When the can end is made, it originates as a can end shell, which is formed from a sheet metal product (e.g., without limitation, sheet aluminum; sheet steel). The shell is then conveyed to a conversion press, which has a number of successive tool stations. As the shell advances from one tool station to the next, conversion operations such as, for example and without limitation, rivet forming, paneling, scoring, embossing, and tab staking, are performed until the shell is fully converted into the desired can end and is discharged from the press.

In the can making industry, large volumes of metal are required in order to manufacture a considerable number of cans. Thus, an ongoing objective in the industry is to reduce the amount of metal that is consumed. Efforts are constantly being made, therefore, to reduce the thickness or gauge (sometimes referred to as “down-gauging”) of the stock material from which can ends, tabs, and can bodies are made. However, as less material (e.g., thinner gauge) is used, problems arise that require the development of unique solutions. By way of example, a common problem associated with can ends for food cans is that they are subject to pressure changes associated with processing the food product within the can. More specifically, substances (e.g., without limitation, liquid; food; any other suitable substance) are commonly packaged in vacuum sealed cans. For example, a typical process for vacuum packaging food in metal cans includes filling the cans with uncooked food, sealing the can end or lid on the can and placing the can into an oven. This process is referred to as a retort process. As the food is cooked, pressure builds within the can. Then the can is cooled. Thus, the retort process induces internal (i.e., positive) pressure, followed by external (i.e., negative) pressure. The combination of the internal and external pressures induces stress on the end panel of the can end. Accordingly, for can ends and shell designs made from material having a reduced gauge or reduced blank size, such pressures and stresses tend to cause the end panel to permanently deform and/or wrinkle.

FIGS. 1A and 1B, for example, show an easy open can end2before (FIG. 1A) and after (FIG. 1B) the retort process. The can end2includes an opener (e.g., without limitation, pull tab4), which is attached (e.g., without limitation, riveted) to a tear strip or severable panel6. The severable panel6is defined by a scoreline8in the exterior surface10(e.g., public side, shown) of the can end2. The pull tab4is structured to be lifted and/or pulled to sever the scoreline8and deflect and/or remove the severable panel6, thereby creating an opening for dispensing the contents of the can (not shown in the top plan views ofFIGS. 1A and 1B). The can end2in the example ofFIGS. 1A and 1Bis a 300 diameter end2, and the panel6includes an up-panel12consisting of an arcuate raised area that extends outwardly from the public side10of the panel6and around the perimeter of the panel6. As shown inFIG. 1B, the stresses caused by the internal and external pressures associated with the retort cooking process cause the panel6to permanently deform (e.g., without limitation, wrinkle) See, for example, the wrinkles and deformed sections generally indicated by reference14inFIG. 1B.

There is, therefore, room for improvement in can ends, and in tooling and methods for providing such can ends.

SUMMARY

These needs and others are met by embodiments of the disclosed concept, which are directed to a can end having a retort resistant panel, and tooling and methods for providing such can ends. Among other benefits, the unique design of the can end provides increased strength and resistance to undesirable deformation (e.g., without limitation, wrinkling) of the can end panel caused, for example, by the pressures associated with the retort cooking process, without requiring an increase in the thickness or gauge of the stock material from which the can end is made or an undesirable increase in the depth of the can end panel.

As one aspect of the disclosed concept, a can end is provided, which is structured to be affixed to a can. The can end comprises: a recessed panel defined by an upwardly extending chuck wall, the panel having a product side structured to face toward the interior of the can, and a public side disposed opposite the product side; a peripheral scoreline disposed in the public side of the panel proximate to the base of the chuck wall; a tab fastened to the panel by a rivet, the tab being operable to sever the peripheral scoreline and open the can end; a pressure resistance bead extending around the panel inboard of the peripheral scoreline and outboard of the rivet; and a saw tooth panel formation disposed proximate to the pressure resistance bead inboard of the pressure resistance bead.

The panel may include a planar portion inboard of the saw tooth panel formation, wherein the planar portion has a depth. The saw tooth panel formation may comprise a plurality of bends and a drape defined by the distance between a first one of the bends and a second adjacent one of the bends. The ratio of the depth of the panel to the drape may be from about 1:1 to about 1:4. The saw tooth panel formation may further comprise a peak, and the drape may be symmetrical on opposing sides of the peak. The saw tooth panel formation may begin proximate to one side of the tab, extend around the panel inboard of the pressure resistance bead, and end proximate to the opposite side of the tab.

Tooling and a method for making the aforementioned can end are also disclosed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The specific elements illustrated in the drawings and described herein are simply exemplary embodiments of the disclosed concept. Accordingly, specific dimensions, orientations and other physical characteristics related to the embodiments disclosed herein are not to be considered limiting on the scope of the disclosed concept.

As employed herein, the terms “can” and “container” are used substantially interchangeably to refer to any known or suitable container, which is structured to contain a substance (e.g., without limitation, liquid; food; any other suitable substance), and expressly includes, but is not limited to, food cans, as well as beverage cans, such as beer and soda cans.

As employed herein, the term “can end” refers to the lid or closure that is structured to be coupled to a can, in order to seal the can.

As employed herein, the term “can end shell” is used substantially interchangeably with the term “can end.” The “can end shell” or simply the “shell” is the member that is acted upon and is converted by the disclosed tooling to provide the desired can end.

As used herein, the term “pull tab” or “tab” refers to an opening device (e.g., opener) made from generally rigid material that has undergone one or more forming and/or tooling operations, and which is structured to be suitably affixed to a can end for the purpose of being pivoted to sever a score line and open at least a portion of the can end.

FIGS. 2 and 3show a can end100in accordance with a non-limiting embodiment of the disclosed concept. As partially shown in phantom line drawing inFIG. 2, the can end100may be suitably affixed (e.g., without limitation, seamed) to a can200.

Continuing to refer toFIGS. 2 and 3, and also to the sectional views ofFIGS. 4A and 4B, the can end100includes a recessed panel102, which is defined by an upwardly extending chuck wall104. The panel102has opposing product and public sides106,108(both shown inFIGS. 4A and 4B). A peripheral scoreline110is disposed on the public side106of the panel102proximate to the chuck wall104within the center panel radius, as best shown inFIGS. 4A and 4B. A tab112or other suitable opening mechanism (not shown) is fastened to the panel102by a rivet114. The tab112is operable to sever the peripheral scoreline110and open the can end100in a generally well known manner.

As previously noted hereinabove with respect toFIGS. 1A and 1B, known can ends (see, for example, can end2ofFIGS. 1A and 1B) formed from relatively thin gauge material are known to wrinkle or otherwise undesirably deform (see, for example, wrinkled or deformed portions14of can end2ofFIG. 1B) when subjected to stress such as, for example and without limitation, the stresses associated with the retort cooking process. Specifically, investigation has revealed that, for an easy open end2of the type shown inFIGS. 1A and 1B, the retort process induces an internal (i.e., positive) can pressure followed by an external (i.e., negative) can pressure. The combination of the internal and external pressures induce excessive stress on the can end panel6(FIGS. 1A and 1B) such that the panel6permanently deforms and/or wrinkles, as indicated generally by deformed areas14inFIG. 1B. Among other disadvantages, such wrinkles14present an aesthetic issue and are generally deemed to be unacceptable by customers.

Turning again toFIGS. 2-4B, the disclosed can end100overcomes the aforementioned disadvantages by incorporating a pressure resistance bead116, which extends around the panel102inboard of the peripheral scoreline110and outward of the rivet114, as well as a saw toothed panel formation118, which is disposed proximate to the pressure resistance bead116inboard thereof. It will be appreciated, therefore, that the disclosed concept involves a completely new and unique can end panel design, which effectively distributes stresses associated with the retort cooking process to resist permanent panel deformation or wrinkling Thus, it will be appreciated, for example, thatFIG. 3is indicative of a can end100in accordance with the disclosed concept, both before and after the retort cooking process. In other words, the disclosed concept enables easy open can ends (e.g.,100) to be produced, without resorting to increasing the thickness or gauge of the stock material from which the can ends (e.g.,100) originate, and without requiring the depth (e.g., depth126ofFIG. 4A) of the can end panel102or chuck wall depth or shell panel height to be undesirably increased. Such an increase undesirably results in increased cut edge or a larger blank diameter to make the shell. In accordance with the disclosed concept, the amount of material (e.g., without limitation, sheet metal) required to produce the can ends100is minimized, and the can ends100are cost-efficient to manufacture.

The can end100also includes a flange144, which extends outwardly from the top of the chuck wall104, and is structured to be suitably seamed to side walls202,204(partially shown in phantom line drawing inFIG. 2) of can200(partially shown in phantom line drawing inFIG. 2) or other suitable container (not shown) to secure the can end100thereto.

The pressure resistance bead116and saw tooth panel formation118, also interchangeably refer to as a “flat” panel design because the overall height of the panel102does not change, will now be described in greater detail. Specifically, the pressure resistance bead116functions, in large part, to resist wrinkling or other deformation during the positive pressure portion of the retort cooking process cycle, and the saw tooth panel formation118or flat panel design, functions, in large part, to resist panel deformation during the negative pressure portion of the retort cooking process cycle. The pressure resistance bead116and saw tooth panel formation118are perhaps best shown in the enlarged section view ofFIG. 4A.

It will be appreciated that the non-limiting example pressure resistance bead116shown and described herein is provided solely for purposes of illustration and is not intended to limit the scope of the disclosed concept. For example, the bead116could be disposed at another suitable location on the end100and/or could have a different shape and/or geometry, without departing from the scope of the disclosed concept. The example pressure resistance bead116is a downbead. That is, it extends inwardly from the public side108of the can end panel102, or outwardly from the product side106of the panel102, as shown inFIG. 4A. It will be appreciated, however, that the pressure resistance bead116could alternatively be an upbead (not shown), which extends outwardly from the public side108of the can end panel102, in the opposite direction, without departing from the scope of the disclosed concept. Preferably, the pressure resistance bead116has a ratio of bead height or depth120to width121of about 133:1 to about 1:1. In one non-limiting example, the pressure resistance bead116has a height or depth120from about 0.0060 inch to about 0.0200 inch, and width121from about 0.0820 inch to about 0.0200 inch when measured as shown inFIGS. 4A and 7. As best shown in the isometric and top plan views ofFIGS. 2 and 3, respectively, the pressure resistance bead116extends around the can end panel102proximate the perimeter thereof. More specifically, the tab112of the can end100includes opposing nose and lift portions122,123, wherein the exemplary pressure resistance bead116passes beneath the nose portion122, outboard of the rivet114, but inboard of the peripheral scoreline110, as shown.

The geometry of the saw tooth panel formation118, is also important to provide retort resistance. Among other unique features, the disclosed saw tooth panel formation118preferably includes a plurality of bends128,130,132,134(best shown in the side elevation sectional views ofFIGS. 4A and 9), without changing the depth126of the planar portion124of the can end panel102disposed inboard of the saw tooth panel formation118. In other words, bends128and132are substantially disposed in the same horizontal plane, and bends130and134are substantially disposed in the same horizontal plane, as shown in the non-limiting example ofFIG. 4A. Additionally, the drape136, or distance between a first one of the bends128and a second adjacent one of the bends130, is preferably symmetrical. That is, the example saw tooth panel formation118includes a peak138, defined by second bend130, and the drape136is symmetrical on opposing sides of such peak138, as shown inFIG. 4A. It will, however, be appreciated that the saw tooth panel formation118could have any known or suitable alternative shape, geometry, and/or configuration, without departing from the scope of the disclosed concept. For example and without limitation, it could be asymmetrical and/or the bends128,130,132,134could be in different horizontal planes. In accordance with one non-limiting example, the drape136was about 0.075 inch. Thus, the ratio of the depth126of the panel102to the drape136is preferably about 1:1 to about 1:4. It will be appreciated that this is relatively high for easy open can ends, which typically have a panel depth to drape ratio of approximately 1:10. Moreover, conventional can end panels (see, for example, panel6of can end2ofFIGS. 1A and 1B) do not have a symmetrical depth or drape.

It will be appreciated that the saw tooth panel formation118is preferably located proximate to the pressure resistance bead116on the outer portion of the can end100, towards the perimeter thereof. In the example shown and described herein, the saw tooth panel formation116begins proximate to one side140of the tab112, extends around the panel102inboard of the pressure resistance bead116, and ends proximate to the opposite side142of the tab112, as shown inFIGS. 2,3and10F.

Tooling300and associated methods for making the can end100will now be described with reference toFIGS. 5-10F. It will be appreciated that the tooling300may be coupled to dies, which are in turn coupled to a conversion press in a generally well known manner. The conversion press and dies are not expressly shown herein for simplicity of illustration and economy of disclosure. It will further be appreciated that the tooling300and associated forming steps or processes described herein may be employed in any known or suitable number and/or configuration of tooling stations in the conversion press, where each station generally includes one or more tools and each of the tools performs a tooling operation on the material. While a limited number of stations are shown and described herein, it will be appreciated that the method of making the can end100in accordance with the disclosed concept could include numerous other known or suitable stations not depicted herein. It will further be appreciated that each of the stations could be located, (e.g., without limitation, housed) in separate machine housings, in a single machine housing, or in any suitable combination thereof. Finally, it will be appreciated that the stock material from which the can ends100are made can be conveyed through the conversion press by any known or suitable means.

In accordance with the disclosed concept, forming the can ends100including pressure resistance bead116and saw tooth panel formation118generally involves up to six or more forming steps, a non-limiting example of which is sequentially depicted inFIGS. 10A-10F. Specifically,FIG. 10Aillustrates a bubble form, which may occur in a first tooling station.FIG. 10Billustrates a first rivet form and finger panel process, which may be performed in a second tooling station.FIG. 10Cillustrates a second rivet form and formation of the disclosed pressure resistance bead116, which may occur in a third tooling station.FIG. 10Dillustrates a third rivet form and formation of the scoreline110, which may occur in a fourth tooling station.FIG. 10Eillustrates a fourth rivet formation and formation of the disclosed saw tooth panel formation118, which may occur in a fifth station. Finally,FIG. 10Fillustrates a tab wipe down after the tab112has been attached to the can end100and the rivet114has been staked to secure the tab112thereto. Again, it will be appreciated that the aforementioned forming steps and processes, as well as the corresponding tooling stations, are provided solely for purposes of illustration in accordance with one non-limiting embodiment of the disclosed concept.

The tooling assembly400for forming the pressure resistance bead116is further illustrated inFIGS. 5-7, and the tooling assembly500for forming the saw tooth panel formation118is further illustrated inFIGS. 8 and 9. Specifically, the first tool assembly400includes a first tool402and a second tool404, which is disposed opposite the first tool402and is structured to cooperate with the first tool402to form the pressure resistance bead116in the panel102, as previously described. As best shown inFIGS. 6 and 7, the first tool402of the example first tool assembly400includes a planar portion406and a recess408, which extends inwardly from the planar portion406. The second tool of the first tool assembly400includes a protrusion410. The protrusion410is structured to extend into the recess408. As it does so, the protrusion410acts upon (e.g., forms) the can end panel102to form the pressure resistance bead116therein, as best shown inFIGS. 6 and 7.

The second tooling assembly500includes a first tool502and a second tool504disposed opposite from the first tool502and structured to cooperate with the first tool502to form the saw tooth panel formation118proximate to the pressure resistance bead116. The first tool502of the example second tool assembly500includes a forming member506having a projection508, a first planar portion510disposed on one side of the projection508, and a second planar portion512disposed on the opposite side of the projection508, as shown inFIG. 9. The second tool504of the second tool assembly500includes a first member514having an offset protrusion516, as shown. In operation, the projection508of the first tool502is structured to move toward the first member514of the second tool504as the offset protrusion516of the first member514of the second tool504moves toward the second planar portion512of the first tool502. In this manner, a plurality of bends128,130,132,134are formed in the panel102of the can end100to form the desired saw tooth panel formation118. More specifically, the first member514includes first and second opposing sides518,520, and the second tool504includes a second member522movably disposed on the first side518, and a third member524movably disposed on the second side520. The first tool502further includes a supporting member526movably disposed beside the forming member506. The supporting member526includes a shoulder528, as shown. Accordingly, as illustrated inFIG. 9, in operation, the third member524, which in the example shown and described herein is a spring-loaded clamping member, cooperates with the supporting member526to support the pressure resistance bead116. Then, the second member522cooperates with (e.g., without limitation, moves toward) the first planar portion510of the first tool502to form the first bend128of the saw tooth panel formation118, the projection508of the first tool502forms the second bend130of the saw tooth panel formation118, the offset protrusion516of the first member514of the second tool504forms the third bend132of the saw tooth panel formation118, and the shoulder528of the supporting member526forms the fourth bend134of the saw tooth panel formation118.

FIG. 11illustrates a pair of finished can ends100,100′, formed in accordance with the aforementioned tooling and method, and stacked one on top of the other. In accordance with one non-limiting embodiment of the disclosed concept, the stack height150when the can ends100,100′ are stacked, as shown, is about 0.027 inch. It will be appreciated, however, the can ends (e.g., without limitation,100,100′) could have any known or suitable alternative stack height (e.g., without limitation,150) or other stacking characteristic, without departing from the scope of the disclosed concept.

Accordingly, the disclosed concept provides a can end100having an entirely different end panel design for resisting wrinkling or other deformation caused, for example and without limitation, by pressures and stresses associated with the retort cooking process. Specifically, the can end panel102incorporates a pressure resistance bead116and a unique saw tooth panel formation118, to distribute and accommodate the positive and negative pressures and associated stresses caused by the retort process. Thus, a cost-effective can end100is provided, which can be produced using a minimal amount of material (e.g., without limitation, sheet metal) while affording enhanced resistance to undesirable permanent deformation.