US3401822A - Container opening devices - Google Patents

Description

se tylv, 1968 E. c. FRAZE 3,401,822

CONTAINER OPENING DEVICES Filed May 16, 1966 5 Sheets-Sheet 1 M/VE/VTGA. Ermd/ C F/v ze Sept. 17, 1968 E. c. FRAZE 3,401,822

CONTAINER OPENING DEVICES Filed May 16, 1966 3 Sheets-Sheet 2 9 m/l a/vrozu frma/ 6? F775 Sept. 17, 1968 E. c. FRAZE 3,401,822

CONTAINER OPENING DEVICES Filed May 16, 1966 5 Sheets-Sheet 5 m/va/vraa fr/rm/ ct Frye ##araeff United States Patent 3,401,822 CONTAINER OPENING DEVICES Ermal C. Fraze, 355 W. Stroop Road, Dayton, Ohio 45429 Continuation-impart of application Ser. No. 348,150, Feb. 28, 1964. This application May 16, 1966, Ser. No. 556,531

14 Claims. (Cl. 220--54) ABSTRACT OF THE DISCLOSURE This disclosure describes an easy opening container wall in which a line of weakness in the container wall defines a tear strip having a leading end and a tab is joined to the leading end of the tear strip by a rivet formed integrally with the material of the tear strip. The tab has an aperture therein through which the rivet protrudes and the sheet material of the tab surrounding the rivet is offset downwardly toward the leading end of the tear strip.

This application is a continuation-in-part of my copending application of the same title, Ser. No. 348,150, filed Feb. 28, 1964, now abandoned.

This invention relates to a container having a manually removable tear strip for access to the contents and, more particularly, pertains to such container in which a tab is connected to the tear strip to function as a second-class lever for initiating the tearing action.

The tab is directly connected to the end of the tear strip near the fulcrum end of the tab and in the usual construction the fulcrum end of the tab is relatively Wide and overlies not only the tear strip but also the container wall on the opposite sides of the tear strip, the theory being that the support of the adjacent areas of the container wall are required for the fulcrum action. With the fulcrum force spread laterally in this manner initiation of the tearing action is accomplished solely by the lifting force that the tab applies to the end of the tear strip.

The present invention is directed to the problem of providing -a more effective and reliable severance operation. This problem is solved by restricting the fulcrum force to the tear strip itself instead of distributing the fulcrum force laterally to the container wall on opposite sides of the tear strip. With both the lifting force and the fulcrum force confined to the tear strip, two opposite forces act on the tear strip at closely adjacent points. Thus the leverage action distorts the leading end of the tear strip simultaneously in opposite directions from the plane of the adjacent container wall and this double action proves to be especially reliable for effectively severing the tear strip from the container.

A second problem to which the invention is directed is spillage of the liquid content in the course of the filling operation. The prevalent procedure for producing such a container filled with a beverage comprises the following steps in sequence: a cylinder is for-med for the body of a can; a first end wall disk is formed with a scored tear strip and provided with an associated tab to serve as the manually operable top of the can; a second plane end wall disk is formed to serve as the bottom of the can; a first end wall disk that is equipped with the tear strip is assembled to one end of the cylinder; this assembly is positioned with its open end uppermost in an automatic filling machine to serve as an open top container for receiving the liquid beverage; a measured quantity of the liquid is poured into the open top container; and finally the second plane end wall is assembled to the uppermost open end of the can to complete the product.

It has been found that some of the filled cans pro- 3,401,822 Patented Sept. 17, 1968 duced in this manner are underweight, the can failing to contain the predetermined quantity of liquid. When this trouble occurs, careful checking of the automatic machine reveals no fault in the measuring of the dispensed quantity of liquid but the presence of spilled liquid is evident on parts of the machine in the filling zone.

The solution to this problem of spillage as taught by the present invention is based on the discovery that the cause of the spillage is what may be termed bistable oil-canning capability on the part of the lower scored bottom end wall of the open container that is being filled. The operation of scoring the tear strip in the end wall of the can displaces metal in both lateral directions from the two score lines that define the opposite sides of the tear strip with consequent increase in the area of the end wall and resulting outward bulging of the end wall. It has been discovered that the bulging makes the can end bistable in the sense that if a force is applied to the convex face of the end wall, the end wall will snap to the opposite convex configuration and will remain in either of the two convex configurations to which it may be snapped; and it has been further discovered that more or "less frequently the impact of the liquid on the bottom of the open top container in the course of the filling operation triggers an oilcanning action or sudden reversal from outward bulging of the end wall to inward bulging, the reversal occurring with a snap action that throws some of the liquid out of the open top of the container.

The present invention teaches that the troublesome spillage can be prevented by suitably offsetting the scored end Wall of the can to compensate in part for the displacement of the metal by the scoring operation and, more important, to make the end wall monostable in the sense that it has a normal convex configuration and while the end wall may be distorted out of the normal configuration it will return to its normal configuration when the distorting force is removed. Such an end wall cannot be triggered to reverse its configuration with a snap action. In the preferred practice of the invention offsets are provided in the end wall in the form of inward depressions that are spaced from the central area of the end wall on opposite sides of the tear strip. It is to be understood, however, that the depression may be outward. The offsets reduce the susceptibility of the end wall to triggered oil-canning in two ways, first, by drawing metal in opposite directions away from the tear strip in a balanced manner to reduce the bulging of the end wall, and second, by stiffening the sheet metal against reversal of the bulge.

In one practice of the invention the metal of the tear strip itself is additionaly offset for further assurance that the end wall will not behave in the undesirable manner. As will be explained, a feature of this particular practice of the invention is that the offset in the tear strip has the further function of cooperating to confine the fulcrum action of the tab to the area of the tear strip.

The invention is further directed to the need to make the tab more convenient and less hazardous to manipu late for carrying out the leverage action. When the beverage-filled can is fabricated and filled, the tab lies flat against the wall of the can because otherwise the tab would interfere with the handling of the parts by automatic machinery and also because compactness is required for packing the cans for shipment. Too often, however, it is difficult to lift the flat tab from its starting position. It is also too often difficult to grip the tab effectively because of the smoothness of the metal. Many tabs are stiffened by one or more outwardly embossed longitudinal ribs which are not only smooth but also reduce the area that is frictionally, gripped by the operators fingers.

This last problem is met by a number of provisions which work together to facilitate the leverage manipulation of the tab.

An important provision is the formation of the tab with stiffening portions along its opposite longitudinal margins to leave the central area of the tab fully available for friction grip by the operator. To take advantage of the elimination of the central longitudinal ribs another provision is the embossing of the central area of the tab to provide the central area with a broken surface to facilitate frictional gripping of the tab. The embossing may be in the form of relatively narrow outwardly embossed transverse ribs or may be in the form of sharp outwardly embossed minute bosses which may be aptly termed hobnails. In one practice of the invention, an additional inwardly embossed transverse rib is provided on the under side of the tab close to the free end of the tab to facilitate engagement of the under side of the tab by the users thumb.

Another provision may be to bend the free end of the tab slightly upward to facilitate insertion of the users thumb under the tab. A further provision in one practice of the invention is to form a depression in the end wall of the can under the free end of the tab to provide further clearance for insertion of the users thumb. A feature of the invention is that this depression may be a dual purpose depression in that it also serves the above mentioned purpose of preventing oil-canning.

A further problem to which the invention is directed is to keep the structure in the central area of the can top from protruding above the plane of the rim of the end flange or chime of the can top. All protrusions must be confined to the headspace between the web of the can top and the plane of the surrounding rim. Any such protrusion interferes during the fabrication and filling of the cans and interferes with stacking the cans.

It is diflicult to meet this problem when a tab is connected to a tear strip in the can top by a hollow rivet that extends through an aperture in the tab and especially so when the hollow rivet is located at or near the center of the can top. In the first place, the can top bulges to a maximum in the central area and, in the second place, the hollow rivet is usually of substantially axial dimension.

A still further problem is to avoid separation of the tab from the tear strip by elongation or distortion of the aperture of the tab in the course of manipulation of the tab that is intended to initiate severance of the tear strip.

The problem of protrusion is solved. in part, by offsetting or indenting the sheet metal of the can top in the manner heretofore described to reduce the bulging of the can top. The problem of protrusion is solved in further part and the problem of failure of the joint between the tab and the hollow rivet is fully solved by countersin'king the aperture of the tab through which the hollow rivet extends, i.e., by depressing or offsetting inwardly the region r of the tab that surrounds the hollow rivet.

With the tab countersunk or depressed adjacent the hollow rivet, the hollow rivet may be exceptionally short in axial dimension, the short hollow rivet lying well below the plane of the can rim even when the can top bulges to a substantial extent. Fortuitously, the countersinking of the tab adjacent the tab aperture strengthens the tab by forming an offset flange around the tab aperture. Such an offset flange not only locally strengthens the tab against elongation of the tab aperture but also strengthens the rim of the aperture to resist any distortion of the rim that might cause the tab to release the hollow rivet.

The features and advantages of the invention may be understood from the following detailed description and the accompanying drawings.

In the drawings, which are to be regarded as merely illustrative:

FIG. 1 is a plan view of a can top embodying one practice of the invention;

FIG. 2 is an enlarged fragmentary section taken along 4 the line 22 of FIG. 1 showing the fulcrum end of the tab and also showing how the tab is attached to the tear strip;

FIG. 2a is an enlarged fragmentary section along the line 2a-2a of FIG. 1 showing how the free end of the tab is bent upward and also showing how the metal is bent under to avoid a hazardous raw metal edge;

FIG. 2b is an enlarged fragmentary section along the line 2b2b of FIG. 1 showing how the metal is scored;

FIG. 3 is a view similar to FIG. 1 illustrating a second practice of the invention;

FIG. 4 is a section along the line 44 of FIG. 1;

FIG. 5 is a plan view of a can embodying a third practice of the invention;

FIG. 6 is an enlarged fragmentary section along the line 66 of FIG. 5;

FIG. 6a is a fragmentary section along the line 6a6a of FIG. 5;

FIG. 7 is a fragmentary section along the line 77 of FIG. 5 showing the fulcrum end of the tab in end elevation;

FIG. 8 is a plan view of another form of tab;

FIG. 9 is an enlarged section along the line 99 of FIG. 8;

FIG. 10 is a plan view of another can top embodying the invention;

FIG. 11 is an enlarged fragmentary section along line 1111 of FIG. 10;

FIG. 12 is an enlarged fragmentary section along line 12-12 of FIG. 10;

FIG. 13 is an enlarged fragmentary section along line 1313 of FIG. 10;

FIG. 13a is an enlarged fragmentary section along the line 13a13a of FIG. 10;

FIG. 14 is an enlarged fragmentary section along line 14-14 of FIG. 10;

FIG. 15 is an enlarged elevation of the free end of the tab; and

FIG. 16 is an enlarged portion of FIG. 14.

In the first embodiment of the invention shown in FIGS. 1, 2 and 2a, a sheet metal can top, generally designated 20, which may be made of a suitable material such as aluminum or steel is formed in the usual manner with a circumferential groove 22 (FIG. 4) and a peripheral flange 24 in preparation for joining the can top to a cylindrical can body. The can top is scored along a continuous line 25 to form an elongated tear strip 26 and a suitable tab, generally designated 28, is attached to one end of the tear strip to function as a second-class lever for initiating severance of the tear strip from the can top.

In the construction shown, the tear strip 26 is attached to the tab 28 by a hollow rivet 30 that is formed in the metal of the tear strip and, as best shown in FIG. 2, extends through an aperture in the tab in overlapping engagement with the tab. The free end of the tab 28 is folded under as shown in FIG. 2a to present a rounded edge 32 instead of a sharp edge which might cut the users finger. Also as best shown in FIG. 2a the free end of the tab 28 is bent up to form an upwardly inclined flange 34 to facilitate manually gripping of the tab by the user. In the construction shown in FIG. 1 the tab 28 is stiffened longitudinally by a central longitudinal rib 35 and by two flanking longitudinal ribs 36 which straddle the rivet 30.

It can be seen in FIG. 1 that a minor portion of the tab 28, including the fulcrum end of the tab, overlaps one end of the tear strip 26 and overlaps areas of the can top on both sides of the tear strip. This minor portion of the tab is attached to the tear strip 26 by the rivet 30 with the fulcrum end 38 of the tab extending beyond the connection to the tear strip. When the tab functions as a second-class lever to initiate severance of the tear strip, the free end of the tab is lifted up to cause the tab to rock about its fulcrum end 38 for exerting upward pull on the rivet 30 to initiate the severance of the tear strip. After the lever action is completed the tab 28 serves as a the the

the

the

handle for pulling the rest of the tear Strip away from the can top.

When the free end of the tab 28 is lifted, the tab fulcrums about the fulcrum end 38 to exert sufiicient out ward pull on the rivet 30 to cause the leading end of the tear strip to be torn away from the can top, and, in accord with the teaching of the invention care is taken that the fulcrum force is confined to the area of the tear strip 26. For this purpose the tear strip 26 is offset outwardly to form an outwardly projecting boss 40 and, as shown in FIG. 2, the fulcrum end 38 of the tab 28 is curved to form a lip to lie against the boss 40 and to conform to the curvature of the boss.

When the free end of the tab 28 is lifted the boss 40 of the tear strip 26 receives all of the fulcrum force. Thus in the initaial lifting of the free end of the tab 28 all of the leverage force is concentrated on the tear strip and the tear strip is simultaneously distorted in opposite respects at two closely spaced points, the tear strip being distorted outward by the pull on the rivet 30 and being distorted inwardly by the fulcrum force on the adjacent boss 40. It has been found that this double action is highly effective for initiating severance of the tear strip with minimum manual effort.

It is also apparent that the boss 40 serves in effect as a bearing for the fulcrum end 38 of the tab 28, the fulcrum end of the tab being shaped with a curved lip conforming to the curvature of the boss and sliding concentrically over the boss during the initial lifting of the tab.

The fact that the scoring of the sheet metal of the can top 20 actually expands the area of the can top may be understood by referring to FIG. 2b which shows some- 'what diagrammatically how a scoring tool 42 fonrns a scored line in the sheet metal. It is apparent that the penetration of the scoring tool 42 displaces the sheet metal in opposite directions as indicated by the arrows. As heretofore explained, one of the purposes of the present invention is to combat the effects of the bulging of the can top that is caused by this displacement.

In this regard, the first practice of the invention is characterized by the provision of elongated arcuate offsets in the form of recesses or depressions 44 in the can top 20 spaced radially from the center of the can top on opposite sides of the tear strip 26. Obviously the offsets may be outward to form lands or bosses instead of depressions. It has been found that for best results the two elongated depressions 44 should be concentric with reference to the center of the can top 20 to draw metal away from the central area of the can top.

It is apparent in FIG. 1 that the depressions 44 have sloping edges 45, the intent being merely to offset the metal. It is further apparent that the two arcuate offsets 44 draw the sheet metal radially outward in a balanced manner. It also may be appreciated that the arcuate depressions 44 not only reduce the bulging of the metal that is created by the scoring but also greatly increase the rigidity of the can top by virtue of the opposite sloping edges or shoulders 45, both effects serving to discourage bistable oil-canning action.

With reference to the problem of keeping structure in the central area of the can top from protruding above the plane of the rim of the can top, it is to be noted that the two arcuate depressions 44 are helpful to the extent that they reduce the degree to which the central area of the can top bulges in response to the pressure of confined fluid. It is also to be noted in this regard that the rivet 30 may be a low rivet of short axial dimension as shown because the tab 28 is countersunk or offset downwardly in the region of the hollow rivet. Thus, as may be seen in FIG. 2, the hollow rivet need be of a height only sufficient to overhang the thickness of the metal of the tab with the metal of the tab positioned flat against the can top.

As may be seen in FIGS. 1 and 2, the sheet metal tab is stiffened as well as increased in overall thickness by offsetting or embossing of the metal to a nonplanar configuration and the transverse end wall of the hollow rivet lies within the overall thickness of the tab. Thus the tab rather than the hollow rivet is the outermost projection from the end wall into the headspace at the top of the can.

With reference to elimination of any tendency for the tear strip to separate from the hollow rivet by elongation of the tab aperture through which the hollow rivet extends or by distortion of the rim of the aperture, it is apparent from FIGS. 1 and 2 that the countersinking or depressing of the tab around the hollow rivet locally strengthens the tab. Thus it may be seen in FIG. 2 that the tab is formed with an offset or angular flange at the rim of the aperture which flange in effect reinforces the tab. It is also apparent that the local offset configuration of the tab stiffens the rim of the tab aperture to resist any such distortion as would result in release of the hollow rivet by the tab.

In the second practice of the invention illustrated by FIGS. 3 and 4, a tab, generally designated 28a, is provided that is largely similar to the previously described tab 28 as indicated by corresponding numerals to indicate corresponding parts. In this embodiment of the invention, the tear strip 26a that is formed by the scored line 25a is offset outwardly to form a relatively large longitudinal boss 46. The fulcrum end 38a of the tab 28:: rests on the end of the boss 46. It is apparent that when the free end of the tab 28a is elevated the fulcrum end 38a of the tab will rock on the boss 46 of the tear strip with the consequence that all of the fulcrum force is restricted to the area of the tear strip.

In this second embodiment of the invention the can top 20a is provided with two elongated arcuate depressions 44a as heretofore described. It is to be noted however, that the longitudinal boss 46 of the tear strip 26a is also an offset and serves to take up the metal of the can top in the same manner as the two arcuate depressions 44a to eliminate the tendency of the can top to oil-can in a bistable manner.

It is apparent in FIGS. 3 and 4 that in the second embodiment of the invention the tab is countersunk or offset in the region of the rivet 30 with the portion of the tab that immediately surrounds the rivet lying flat against the can top to minimize the extent to which the rivet must extend above the can top for engagement with the tab. The offset configuration of the tab further stiffens the tab around the rim of the aperture that receives the rivet.

FIG. 5 illustrating a third embodiment of the invention shows a can top 20b which has the usual scored line 25!) forming the usual tear strip 26b. A tab 28b is attached to the tear strip 26b in the usual manner by virtue of a rivet 30 that is formed in the tear strip and extends through an aperture in the tab in overlapping engagement with the tab. It can be seen in FIG. 5 that the tab is indented or countersunk in a pronounced manner to follow the periphery of the rivet. The free end of the tab is folded under in the previously described manner to form a rounded edge 32b and the free end of the tab is also bent upward to form an upwardly inclined flange 34b. The tab has a relatively short central longitudinal embossed rib 48 and has two opposite side longitudinal ribs 50 of the same character which straddle the riviet 30.

In the construction shown, the central rib 48 is shortened to provide space on the free end of the tab for an arcuate transverse rib 52 that projects downward and to provide further room for a plurality of minute upwardly projecting bosses 54 that lie away from the transverse rib in the direction of the fulcrum end of the tab. The minute bosses 54 are relatively sharp bosses which are analogous to hob nails.

In lifting the tab to initiate severance of the tear strip and in subsequently using the tab as a handle to complete the severance of the tear strip, the users thumb extends under the free end of the tab and he users forefinger is pressed against the upper surface of the tab. It is apparent that the transverse rib 52 on the underside of the tab near the free end of the tab provides purchase for the users thumb to prevent slippage and at the same time the sharp minute bosses 54 provide purchase for the forefinger to prevent slippage.

In the first two embodiments of the invention, the fulcrum force is confined to the area of the tear strip by the expedient of offsetting the metal of the tear strip out ward under the fulcrum end of the tab. In this third practice of the invention, the same end is accomplished by offsetting the fulcrum end of the tab inwardly towards the tear strip within the area of the leading end of the tear strip. The inward offset 55 of the fulcrum end of the tab is best shown in FIG. 7. By virtue of this inward offset 55, the portions 56 of the fulcrum end of the tab on the opposite sides of the offset are spaced away from the plane of the can top to prevent application of any portion of fulcrum force to the can top outside the area of the tear strip 26b.

In this third embodiment of the invention, the metal of the can top 20b is offset to eliminate bistable oil-canning by forming one large C-shaped depression 58 in the can top, the depression being substantially concentric relative to the center of the can top and preferably being widened near its two ends as shown. In this articular embodiment of the invention the depression 58 serves three purposes in that it not only takes up metal and stiffens the can top by forming two sloping shoulders in opposite radial areas to discourage bistable oil-canning but also extends under the free end of the tab to provide added clearance for the insertion of the users thumb under the tab.

It is further apparent from FIG. 6a that clearance under the free end of the tab for the users thumb is augmented in three ways: first, by the fact that the free end of the tab is bent upward to form the end flange 341:; secnd, by the fact that rib 52 on the underside of the tab elevates the free end of the tab from the can top, and, third, by the fact that the C-shaped depression 58 extends under the free end of the tab.

As best shown in FIGS. 6 and 7 this third embodiment of the invention like the first and second embodiments is characterized by the concept of countersinking or depressing the tab locally in the region surrounding the hollow rivet with the advantages heretofore noted.

FIGS. 8 and 9 show a modified form of the tab. The tab 28c in FIG. 8 is of the same general character as the tab 28b and in the same manner is formed with an inward offset 550 on its leading end to cencentrate the fulv crum force on the tear strip 26c. The tab 280 is formed with two relatively short longitudinal ribs 60 on its opposite sides and is further formed with a central longitudinal rib 62 which has two branches 64 that straddle the hollow rivet 30. The free end of the tab 280 is folded and bent upwardly as heretofore described. As shown in FIG. 9 the tab lies fiat against the can top 20c but the free end of the tab overhangs a C-shaped depression 580, the depression serving to provide added clearance under the free end of the tab.

A fourth embodiment of the invention is shown in FIGS. 10 to 16. A can top d of the usual construction is formed with a C-shaped depression 58d as heretofore described and is further formed with a continuous score line which outlines a tear strip 26d. A tab 28d is attached to the tear strip 26d by the usual rivet 30 and the fulcrum end 38d of the tab rests flat on the tear strip.

A feature of this embodiment of the invention is that the tab 28d is longitudinally stiffened in a manner .which leaves a relatively wide area of the tab available for embossing to favor frictional engagement by the users fingers.

To stiffen the tab 28d longitudinally, the margin of the tab along the two longitudinal sides and along the free end of the tab are offset to tubular cross sectional configuration as may be understood by referring to FIGS. 11, 12 and 13. Thus the tab is characterized by tubular stiffening portions 64 on its opposite longitudinal sides which progressively taper towards the free end of the tab and merge with a tubular portion 65, the tubular portion 65 extending around the arcuate free end of the tab and interconnecting the two tubular stiffening portions 64. It is to be noted in FIGS. 11, 12, 13 and 13a that the marginal sheet metal is rolled completely back on itself so that the edge of the rolled metal actually abuts the underside of the tab with an important reinforcing or stiffening effect.

A single stiffening rib or boss 66 is formed on the longitudinal axis of the tab 28d but is relatively short to leave ample space for a finger grip area provided with distributed minute sharp bosses 68 which function like hob nails on the underside of the tab to promote frictional engagement with the users thumb.

To provide clearance under the free end of the tab, the free end of the tab is initially bowed upward to the configuration indicated by the dotted lines 72 in FIG. 15. Then the tubular portion 65 that extends around the armate free end of the tab is pinched to create the final bowed configuration indicated by the solid lines 74 in FIG. 15. FIG. 16 shows in dotted lines 75 the cross sectional configuration of the tubular portion 65 prior to the pinching operation and shows in solid lines the final configuration achieved by the pinching operation. As may be seen in FIG. 14 the upwardly bowed free end of the tab 28d overhangs the C-shaped depression 58d for augmented clearance and the clearance is further augmented by the fact that the downwardly transverse rib slightly elevates the free end of the tab from the plane of the can top 20d.

My description in specific detail of the selected embodiments of the invention will suggest various changes, substitutions and other departures from my disclosure within the spirit and scope of the appended claims.

I claim:

1. In a container having a thin metal wall, the combination of:

scoring in the metal wall outlining an elongated tear strip; and

a tab to serve as a second-class lever to fulcrum at one end to initiate severance of the tear strip from the remainder of the metal wall,

a minor portion of the tab including the fulcrum end of the tab overlapping one end of the tear strip and overlapping areas of the metal wall adjacent the tear strip, said minor portion being attached to the tear strip with the fulcrum end of the tab extending beyond the connection to the tear strip,

at least a portion of the fulcrum end of the tab that overlies the tear strip being offset towards the tear strip to space the rest of the fulcrum end from said adjacent areas of the metal wall thereby to confine the fulcrum force of the tab to the area of the tear strip,

the reaction to the lever action of the tab being wholly directed to outward. lifting force on the end of the tear strip and simultaneous inward force on the tear strip close to the location of application of the lifting :force to distort the end of the tear strip simultaneously in opposite respects to facilitate initial tearing of the tear strip away from the remainder of the metal wall.

2. In a container having a thin wall of sheet material, the combination of:

scoring in the ;wall outlining an elongated tear strip having a leading end; and

a tab to serve as a second class lever to fulcrum at one end to initiate severance of the tear strip from the remainder of the wall,

a minor portion of the tab including the fulcrum end of the tab overlapping the leading end of the tear strip, said minor portion being attached to the tear 9 strip with the fulcrum end of the tab extending over the tear strip beyond the connection to the tear strip, the fulcrum end of the tab being wider than the leading end of the tear strip for structural strength on the part of the tab with the consequence that the fulcrum end of the tab overlaps not only the leading end of the tear strip but also areas of the wall adjacent the tear strip, one of said fulcrum end of the tab and said leading end of the tear strip being offset towards the other so that the portion of the fulcrum end that ovenlaps said adjacent areas is spaced outward from said adjacent areas to confine the contact of the fulcrum end of the tab with the wall to the area of the tear strip whereby the fulcrum force of the tab is confined to the area of the tear strip, the reaction to the lever action of the tab being wholly directed to outward lifting force on the end of the tear strip and simultaneous inward force on the tear strip close to the lifting force to distort the end of the tear strip simultaneously in opposite respects to facilitate initial tearing of the tear strip away from the remainder of the metal Wall. 3. A combination as set forth in claim 2 in which the leading end of the tear strip is offset outwardly towards the fulcrum end of the tab.

4. A combination as set forth in claim 3 in which the tear strip is olfset outwardly to form a boss elongated longitudinally of the tear strip to take up part of the metal displaced by the scoring operation and thus reduce the tendency of the metal wall to snap in opposite directions in reaction to applied forces.

5. A combination as set forth in claim 2 in which the fulcrum end of the tab is offset towards the leading end of the tear strip.

6. A combination as set forth in claim 3 in which the fulcrum end of the tab is bent in the form of a lip for contact with the offset on the tear strip.

7. In the construction of an end wall of a container wherein a circumferential rim of the container extends beyond the end wall to form a head space between the end wall and the plane of the rim, and wherein the end wall bulges to reduce said head space, and wherein a tab to facilitate manual severance of the tear strip has an aperture therein and a hollow rivet formed in the tear strip extends through the aperture to connect the tab to the tear strip,

the improvement to minimize the extent to which the hollow rivet protrudes into the head space and to stiffen the tab at the aperture and to strengthen the tab against distortion of the aperture, comprising:

the tab being depressed in the region immediately surrounding the aperture to offset the aperture towards the end wall of the container and thereby lessen the axial dimension of the hollow rivet that is required for effective engagement of the tab by the hollow rivet, the depression in the tab offsetting the rim of the tab inward from the outermost surface of the tab and the outer end of the rivet terminating short of the level of said outer surface.

8. An improvement as set forth in claim 7 in which the tabe is a sheet metal member stiffened and increased in overall thickness by offsetting of the Sheet metal from planar configuration; and

in which the outer transverse end wall of the rivet lies within the overall thickness dimension of the tab whereby the tab rather than the rivet is the outermost projection from the end wall into said head space.

9. In an easy opening container construction, the combination of:

a container wall;

a line of weakness in said container wall defining a tear strip having a leading end;

a tab of sheet material for initiating severance of said tear strip from said container wall, said tab overlying said container wall and having an elevated region spaced from the container wall, said tab having an end portion overlying said leading end of said tear strip and a lifting portion remote from said end portion, said end portion of said tab having an aperture therein with the material of the tab in a zone immediately surrounding the aperture being offset downwardly from said elevated region toward the container wall, at least a portion of said elevated region lying laterally of said aperture; and

a hollow rivet formed integrally with said leading end of said tear strip and extending into said aperture of said tab, said hollow rivet having a circumferentially extending bead overlying and clampingly engaging at least some of said zone to secure said tab to said tear strip.

10. A combination as defined in claim 9 wherein said rivets lies at or below the uppermost area of said elevated region.

11. In a container construction, the combination of:

a container wall;

a line of weakness in said container wall defining a tear strip having a leading end;

a tab of sheet material for initiating severance of said tear strip from said container wall, said tab overlying said container wall and having an elevated region spaced from the container wall, said tab having an end portion overlying said leading end of said tear strip and a lifting portion remote from said end portion, said end portion of said tab having an aperture therein with an offset region of the sheet material of the tab at least partially surrounding the aperture extending inwardly from said elevated region towards said container wall to otfset said aperture downwardly from said elevated region towards said container wall, said offset region extending for at least around said aperture and lying closely adjacent thereto; and

a hollow rivet formed integrally with said leading end of said tear strip and extending into said aperture of said tab, said hollow rivet having a circumferentially extending bead overlying and clampingly engaging the rim of said aperture of said tab to secure said tab to said tear strip.

12. A combination as set forth in claim 11 wherein at least a portion of said offset region overlies said leading end of the tear strip.

13. A combination as set forth in claim 11 wherein at least a portion of the elevated region of said tab lies intermediate the lifting portion and the offset region and laterally of the aperture, said rivet does not protrude above the elevated region, and at least a portion of said offset region overlies the leading end of the tear strip.

14. In an easy opening container construction, the combination of:

a container wall;

a line of weakness in said container wall defining a tear strip having a starting portion:

a tab of sheet material for initiating severance of said tear strip from said container Wall, said tab overlying said container wall with a portion of said tab being spaced outwardly from said container wall, said tab having an end portion overlying a portion of said tear strip and a handle portion remote from said end portion, said end portion ofsaid tab having an aperture therein with the aperture being countersunk to lower the aperture beneath the portion of said tab which is spaced therefrom to position said aperture closely adjacent the leading end of the tear strip; and

a hollow rivet formed integrally with said starting portion of said tear strip and extending into said countersunk aperture of said tab to secure said tab to said tear strip, said hollow rivet having a circumferential- 1 l 1 2 1y extending bead overlapping and clampingly engag- 3,151,766 10/ 1964 Henchert 220-54 ing the rim of the aperture in the tab. 3,225,957 12/ 1965 Huth 220-54 References Cited THERON E. CONDON, Primary Examiner.

UNITED STATES PATENTS 5 GEORGE T. HALL, Assistant Examiner.

2,112,231 3/1938 Speidel 220-54

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