US3850124A

US3850124A - Easy opening container wall

Info

Publication number: US3850124A
Application number: US00331645A
Authority: US
Inventors: O Brown
Original assignee: Individual
Current assignee: Dayton Reliable Tool and Manufacturing Co
Priority date: 1970-08-17
Filing date: 1973-02-12
Publication date: 1974-11-26
Anticipated expiration: 1991-11-26

Abstract

An easy opening container wall including a container wall having a line of weakness therein defining a tear portion at least partially removable from the container wall and a tab affixed to the tear portion to initiate severance thereo from the container wall. The tab has a rupturing portion which overlies a location on the container wall closely adjacent the line of weakness. The tab has a hinge line which extends between said location and the region of attachment of the tab to the tear portion so that by manipulating the tab, a segment of the tear portion is forced inwardly generally about a bend line. The tear portion has a weakened region therein positioned to facilitate the inward bending of the segment about the bend line. Although various kinds of tabs may be used, the tab preferably includes a lever portion and an attachment portion joined by a connecting wall. A marginal portion of the tab is bent inwardly to form a curl having a double layer portion which is engageable with the connecting wall to support the latter. According to another feature of the present invention, the tab is made in a strip of sheet material and the carrying strip therefor is positioned at the lifting end of the tab.

Description

United States Patent Brown Nov. 26, 1974 [5 EASY OPENING CONTAINER WALL I [57 ABSTRACT lib/6mm? D y n, fl An easy opening container wall including a container [73] Assignee: Erma] C. Fraze Dayto Ohi wall having a line of weakness therein defining a tear portion at least partially removable from the container Filedi 1973 wall and a tab affixed to the tear portion to initiate [21] Appl No; 331 645 severance thereo from the container wall. The tab has a rupturing portion which overlies a location on the Related Application Data container wall closely adjacent the line of weakness. [62] Division of Ser. No. 64,291, Aug. 17, 1970, Pat. No. e t b has a hinge ne which extends e e Said 3,720,349. location and the region of attachment of the tab to the tear portion so that by manipulating the tab, a seg- [52] U.S. Cl 113/121 C ment of the tear portion is forced inwardly generally [51] Int. Cl B21d 51/44 about a bend line. The tear portion has a weakened [58] Field of Search 113/121 C, 1 F; 220/54 region therein positioned to facilitate the inward bending of the segment about the bend line. Although vari- [56] References Cited ous kinds of tabs may be used, the tab preferably in- UNTTED STATE NT cludes a lever portion and an attachment portion 3 381,848 5/1968 Brown 113/121 c joined by a connecting wall' A marginal 9 of the 31401323 9/1968 Fraze tab is bent inwardly to form a curl having a double 3,435,411 12/1969 Brown layer portion which is engageable with the connecting 3,674,172 7/1972 W lls et a1, wall to support the latter; According to another fea-' 3,683,834 8/1972 Potts et al. 113/1 F ture of the present invention, the tab is made in a strip Primary Examiner-Richard J. Herbst Attorney, Agent, or FirmMario A. Martella of sheet material and the carrying'strip therefor is po-' sitioned at the lifting end of the tab.

16 Claims, 16 DrawingFigures PAIENIEmvZSIQM 3'850, 1 24 sum 1 as 4 PAIENIELKGVZSISH 50,124

SHEET EM 4 1v EASY OPENING CONTAINER WALL This application is a division of Ser. No. 64,291 filed Aug. 17, 1970, now U.S. Pat. No. 3,720,349.

BACKGROUND OF THE INVENTION An easy opening container wall typically includes a container wall, a primary line of weakness in the container wall defining a tear portion at least partially removable from the container wall and a tab connected to the tear portion by suitable attaching means such as a rivet to initiate severance of the tear portion from the container wall. The tab may be of the front opening type in which the tab has a rupturing portion which overlies a location on the container wall closely adjacent the primary score line and is operable upon pivotal movement of the tab to push a segment of the container wall inwardly about a bend line. Alternatively, the tab may be of a rear opening type in which lifting of the lifting end of the tab lifts the leading end of the tear portion upwardly to initiate severance thereof.

Front opening tabs are often used when the tear portion is a relatively large panel such as in a full panel pullout. One problem with this construction is how to facilitate the initial rupturing of the panel from the container wall. Another problem is how to maximize the length of are which is ruptured in response to pivoting of the tab. If an insufficient length of arc is ruptured, continuation of rupture of the tear portion in response to an outward pulling force on the tab is made more difficult.

[t is also important that the tab be sufficiently strong to avoid tearing and structural failure during use thereof. One form of tab which has been used includes a tab body and an attachment portion interconnected by a connecting wall. The tab body has a lifting end and a rupturing or nose end which is forced against the container wall in response to lifting of the lifting end of the tab to initiate severance of the tear portion. The tab has a hinge line intermediate the attaching means and the rupturing end. A problem with tabs of this type is that they have been subject to structural failure and tear out particularly when used on large panels.

Tabs for easy opening containers are typically formed in a strip of sheet material and several operations are performed thereon at several different stations. When the tab is being formed, it is carried between stations in the strip and it is attached thereto by one or more webs or carrying strips. When the tab is nipped from the strip, the web is cut and this results in interruption of the usual outer periphery curl of the tab. This causes weakening of the tab or interference with the construction of various portions of the tab such as the rupturing end thereof.

SUMMARY OF THE INVENTION The present invention facilitates the initiation of severance of the tear portion with a front opening tab. The present invention employs a tab with a hinge line between the attachment means and the rupturing end of the tab and a secondary score line in the container wall. Pivotal movement of the tab about the hinge line thereof bends a segment of the container wall inwardly about a bend line, and the secondary score line is positioned to facilitate the inward bending of such segment of the tear portion.

The secondary score line can advantageously lie at least in part between the tab attaching means and the rupturing end of the tab. Preferably at least a portion of the secondary score line lies generally along the bend line about which the segment of the tear portion bends. The secondary score line can advantageously be located immediately under the hinge line in the tab and it may extend in chord-like fashion toward the periphery of the tear portion.

The shape and position of the bend line affects the length of arc of initial rupture. The secondary score line can be used to influence bend line configuration and thus the length of the initial arc of rupture. Specifically the bend line, within limits, tends to take the shape of the secondary score line if the secondary score line lies at least in part along the region which the bend line would inherently fall. Thus, if the secondary score line is generally chord-like, the bend line will also tend to be generally chord-like.

Another aspect of this invention is to interrelate the secondary score line with an anti-fracture score line. An anti-fracture score line is sometimes provided in the tear portion adjacent the primary score line for allowing flexure of a section of the tear portion when the container is subjected to an impact force such as when the container is dropped. According to this aspect of the present invention, a segment of the anti-fracture score is positioned to facilitate the inward bending of the segment about the bent line.

The tab is preferably constructed of sheet material and may include a tab body and an attachment portion interconnected by a connecting wall with the sheet material of the tab adjacent the juncture of the attachment portion and the connecting wall being sufficiently pliable to form the hinge in the tab. To strengthen the tab, a marginal portion of the sheet material of the tab body is turned inwardly to form an outer reinforcing bead or curl along the periphery of the tab body. To strengthen the tab adjacent the connecting wall, a section of the curl adjacent the connecting wall is bent over to form a double layer of sheet material. The double layer of sheet material is positioned so that it is engageable with the connecting wall to support and reinforce the latter during operation of the tab.

The tab is preferably formed at one end of the tab body with a rupturing element. The rupturing element may be formed by merely appropriately shaping the outer curl or by interrupting the outer curl to form a rupturing flange.

Upon manipulation of the tab to sever the primary score line, the tab body pivots about a hinge line extending generally transverse to the tab intermediate the ends thereof. This pivotal movement of the tab body causes the rupturing element to move in an arc toward the container wall and rearwardly, i.e., toward the central region of the container wall. The movement of the rupturing element rearwardly about the hinge line is known as travel back and should be minimized in front opening applications. Travel back also occurs after initial rupture of the primary score line because the tab and tear portion bend about different hinge lines.

One reason travel back is undesirable in front opening applications is that it causes the rupturing element to scrape across the container wall. This scraping action may scrape metal particles from the container wall, which upon severance ofthe primary score line may mix with the contents of the container. To facilitate initial severance of the primary score line, the rupturing flange should be forced generally perpendicularly downwardly at about the moment that sufficient pressure has been created to rupture the primary score line. This is more difficult to provide for as travel back increases. Furthermore, the rupturing element should apply its force directly to the sheet material at the primary score line and this is also more difficult to provide for as travel back increases.

To minimize travel back, the present invention provides for moving of the hinge line of the tab closer to the plane of the tear portion. This also moves the hinge line of the tab closer to the bend line in the tear portion. Specifically it has been found that the hinge line in the tab can be moved by using a portion of the outer curl to support the connecting wall. Moreover, the location at which the connecting wall is supported by the curl or head affects travel back. By moving the support region nearer the container wall, the hinge line of the tab is moved closer to the container wall and closer to the hinge line in the tear portion. Accordingly, travel back is reduced. Normally, the sheet material from which the tab is constructed is thicker than the width of the primary score line. Accordingly, to ensure that the rupturing element will interlock with the sheet material at the score line, a portion of the rupturing element preferably overhangs a region of the container wall ahead, i.e., outside, of the tear portion.

To avoid weakening of the tab due to nipping the tab from the strip of sheet material in which it is formed, the present invention provides for the tab to be carried in the strip at the lifting end of the tab. According to this aspect of the present invention, the sheet material of the strip is severed to form a tab blank with the tab blank being integrally connected to the strip by a web at the lifting end of the tab. Preferably, the web is located generally centrally of the lifting end of the tab. The tab blank is then deformed to form a tab of the desired configuration with the tab being retained in the strip by the web. When the tab is nipped out of the strip, the outer curl of the tab is interrupted at the lifting end of the tab. Accordingly, to the extent that the tab is structurally weakened as a result of a nipout, such weakening occursat the lifting end of the tab where such weakening effect can be tolerated. If the outer curl is weakened in the longitudinally extending portions of the curl, the ability of the tab to withstand bending forces during use would be reduced. Also, if the web or carrying strip were at the nose end of the tab, it may interfere with the construction of the nose end. The nipout point is preferably-recessed to avoid possible injury to the user as a result of contact with the severed sheet material.

The invention, both as to its organization amd method of operation together with further features and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying illustrative drawings.

BRIEF DESCRIPTION OF THE DRAWINGS strip of sheet material.

FIG. 6 is an enlarged fragmentary sectional view similar to FIG. 2 with the tab body having been pivoted to initiate severance of the tear portion.

FIG. 7 is atop plan view similar to FIG. 6 showing another configuration of secondary score line.

FIG. 8 is a top plan view of another form of easy opening container constructed in accordance with the teachings of this invention.

FIG. 8a is a sectional view taken generally along line 8a-8a of FIG. 8 with the lifting end of the tab body having been raised slightly to illustrate the idle lift obtainable with this embodiment of the invention.

FIG. 9 is a bottom plan view of another form of tab constructed in accordance with the teachings of this invention.

FIG. 10 is an enlarged fragmentary sectional view taken generally along lines 10-10 of FIG. 12.

FIG. 11 is a fragmentary elevational view of the tab looking generally in the direction of the arrows 11-11 of FIG. 10.

FIG. 12 is a top plan view showing the tab of FIG. 9 installed on a can end.

FIGS. 13 and 14 are sectional views similar to FIG.

2 showing the effect of supporting the connecting wall at different locations.

Referring to the drawings and in particular to FIG. 1 thereof, reference numeral 11 designates an easy opening container wall constructed in accordance with the teachings of this invention. The easy opening container wall 11 includes a container wall in the form of a can end 13 constructed of sheet material such as aluminum. The can end 13 has a primary score line 15 therein defining a tear portion or panel 17 which is removable from the can end 13.1n the embodiment illustrated, the primary score line 15 and the panel 17 are circular in plan, it being understood that other configurations may be utilized if desired. Although the primary score line 15 and the panel 17 can be of any size desired, in the embodiment illustrated the panel 17 covers substantially the entire area in plan of the can end 13. The can end 13 has a peripheral attaching flange 19 for attaching the can end 13 to a can body 21 (FIG. 2).

The easy opening container wall 11 also includes a tab 23 connected to the panel-l7 by attaching means such as a rivet 25 formed integrally with the sheet material of the panel 17. A secondary score line 27 is formed in the panel 17 adjacent the rivet 25 as shown in FIG. 1.

The tab 23 includes a tab body 29 and an attachment portion 31 integrally joined to the tab body by a connecting wall 33 (FIG. 2). The tab 23 preferably integrally formed of sheet material such as aluminum and the tab body 29 surrounds the attachment portion 31. The tab body 29 defines an opening 35 sized to accommodate the finger of a user. The tab body 29 is relatively rigid longitudinally and includes a lifting end 37 and a rupturing or nose end 39 which overlies a location 41 (FIG. 2) on the can end 13 closely adjacent the score line 15. The tab 23 is positioned generally radially on the panel 17 with the lifting end 37 lying radially inwardly of the rupturing end 39.

The connecting wall 33 attaches the attachment portion 31 to the tab body 39 at a region adjacent the rupturing end 39. The sheet material of the tab along and adjacent the connecting wall 33 is sufficiently pliable to hingedly attach the tab body 29 to the attachment portion 31. The construction of the tab is such as to form a hinge line 42 (FIGS. 3 and 6). Thus, the tab body 29 serves as a lever.

The details of the tab 23 can best be seen in FIGS. 2-4. An inner peripheral region of the sheet material of the tab surrounding the opening 35 is turned outwardly to form an inner reinforcing head 43 which extends completely around the opening 35 except in the region on the attachment portion 31. Similarly, a marginal portion of the sheet material of the tab body 29 is turned inwardly to define an outer reinforcing bead or curl 45 which extends substantially completely around the outer periphery of the tab body. The lifting end 37 of the tab body 29 has a notch 47 therein. The outer reinforcing bead 45 is interrupted at the notch 47 and is severed along a radial line 49 at the rupturing end 39 of the tab to facilitate formation of the rupturing end. The bead 45 is uninterrupted at the nose end 39 except for the radial line 49.

The connecting wall 33 slopes downwardly as shown in FIGS. 2 and 3. The attachment portion 31 has a rivet receiving aperture 51 therein.

The sheet material at the rupturing end 39 is deformed to form a solid rupturing element or point 53 which overlies the location 41 on the score line 15. The sheet material of the outer curl 45 at the rupturing end 39 is used to support the connecting wall 33 as shown in FIGS. 2 and 3. Specifically, theconstruction includes first and second layers of

sheet material

55 and 57 interconnected by a bend portion 59 of the sheet material, to define a reinforcing sectionof the connecting wall 33. The bend portion 59 is engageable with a face 61 of the connecting wall 33 at a region as close to the can end as the dimensions of the sheet material permit to support the connecting wall 33 during use of the tab. The

layers

55 and 57 support the connecting wall 33 to a greater extent than would be possible if only a single layer were utilized for this purpose. This also gives a greater bend radius to help avoid fracturing.

The hinge line 42 lies substantially along the region of contact between the bend portion 59 and the face 61. It is apparent from FIGS. 1 and 4 that the hinge line 42 of the tab 23 lies intermediate the rivet 25 and the rupturing end 39. Furthermore, the hinge line 42 extends in a direction generally transverse of the longitudinal direction of the tab 23.

The secondary score line 27 in the embodiment illustrated has a straight line segment underlying the tab 23 and curved end portions which terminate adjacent regions of the primary score line 15. A central region of the secondary score line 27 substantially underlies the hinge line 42 of the tab 23 as shown in FIG. 1. Thus, this region of the secondary score line 27 lies intermediate the rivet 25 and the location 41 (FIG. 2). However, as shown in FIG. 3, the score line 27 lies intermediate the hinge line 42 and the rivet 25.

In operation of the easy opening container wall 11, the lifting end of the tab 37 ismoved away from the panel 17 to thereby pivot the tab body 29 about the hinge line 42. This forces the rupturing end 39, and more specifically the rupturing point 53 against the location 41 of the can end 13 to thereby stress the primary score line 15. Continued upward movement of the lifting end 39 results in rupture of the sheet material along the score line 15 as shown in FIG. 6.

During and after initial rupture or breaking of the score line 15, a segment 63 of the panel 17 is bent inwardly about a bend line which generally lies along a central region of the secondary score line 27. The secondary score line 27 facilitates the inward bending of the segment 63 and makes initiation of severance of the sheet material along the primary score line 15 easier. The sheet material along the secondary score line 27 does not rupture during ordinary pivotal movement of the tab body 29. The secondary score line 27 also tends to increase the length of arc of the primary score line 15 which is ruptured in response to pivotal movement of the tab body 29. Thus, with the construction shown in FIG. 1, the primary score line 15 would be ruptured from the location 41 outwardly to the regions of the primary schore line 15 which are substantially in alignment with the central portion of secondary score line 27. If the secondary score line 27 were not provided, the initial arc of rupture may be shorter than this for a given angular displacement of the tab body 29. Following initiation of severance of the primary score line 15, the user exerts an outward pulling force on the tab body 29 to completely remove the panel 17 from the can end 13. During tab manipulation, the layers and ,57 are operative to supp'ort andstrengthen the connecting wall 33. It should be apparent that the concepts of this invention are applicable to tabs of different construction provided that the tab has a hinge line intermediate the rivet 25 and the rupturing end thereof.

A preferred method for making the tab 23 is illustrated in FIG. 5. A tab blank 65 of the desired configuration is formed in an elongated strip of sheet material 67 by appropriately severing the strip 67 to form a slot 69 and

openings

71 and 73. The tab blank 65 is integrally connected to the strip 67 by a web and the remainder of the periphery of the tab blank 65 is separated from the strip 67 by the slot 69. As shown in FIG. 5, the web 75 is located centrally at the lifting end 37. The slot 69 and the

openings

71 and 73 may be formed simultaneously or sequentially at one or more stations 9 by suitable tooling (not shown). The strip 67 is moved between work stations by any suitable strip stock feeding means (not shown). Subsequently, additional work operations are performed on the tab blank 65 while the tab blank is retained in the strip 67 by the web 75 to thereby convert the tab blank into a tab 23' which may be identical to the tab 23. Finally, the tab 23 is severed from the strip 67 by cutting the web 75.

With reference to FIG. 4, it can be seen that the outer curl 65 is substantially uninterrupted except for the notch 47 which is at a location corresponding to the web 75 when the tab was in the strip 67. The notch 47 recesses raw edges 78 and 78a to protect the user against lacerations. The interruption of the outer curl 45 at the lifting end 37 is the result of cutting the web 75 to free the tab from the strip 67. Thus, the outer cur'l 45 is not interrupted along the longitudinal sides of the tab body 29 where such interruption would result in some weakening of the tab. Nor is the outer curl 45 interrupted at the rupturing end 37 as a result of carrying the tab 23 in the strip 67.

FIG. 7 shows a second embodiment of the invention and portions of the embodiment of FIG. 7 corresponding to portions of the embodiment of FIG. 1 are designated by corresponding reference numerals followed by the letter a. The embodiment of FIG. 7 is identical to the embodiment of FIG. 1 except for the shape of the secondary score line 27a. In the embodiment of FIG. 7, the secondary score line 27a has

end portions

79 and 81 which curve outwardly from a straight central portion 83. The end portions 79 and 8] curve away from the lifting end 37a of the tab 23a generally toward an adjacent region of the primary score line a. Generally the secondary score line 27a is shaped to conform to the bend line which would inherently be formed in the panel 17a if no secondary score line'were provided. Except for the

curved end portions

79 and 81, the positioning and configuration of the score line 27a is identical to the positioning and configuration of the secondary score line 27 (FIG. 1).

FIG. 8 shows an easy opening container wall 85 which represents a third embodiment of the invention. The easy opening container wall 85 includes a container wall in the form of a circular can end 87 having a peripheral attaching flange 89 to secure the can end to a can body (not shown). A primary score line 91 in the can end 87 defines a tear portion93 in the can end 87. The tear portion is elongated with the direction of elongation extending generally radially of the circular can end 87 and the tear portion covers a relatively small area of the can end.

A tab-95 (FIGS. 8 and 8a) is attached to the leading end of the tear portion 93 adjacent the center of the can end 87 by arivet 97 formed integrally with the sheet material of the can end 87. The tab 95 includes a tab body 99 and an attachment portion 101 interconnected by a connecting wall 103. The tab 95 has a lifting end 105 and a nose end 107 which overlies a region of the can end 87 outside of the tear portion 93. The tab 95 is preferably identical to the tab 23'except the former has no rupturing element or point. Rather, the tab 95 has an arcuate cam 108at the nose end thereof adapted to bear againstthe can end 87 during manipulation of the tabrln addition the rivet 97 is spaced from the connectingwall 103 as shown in FIG. 8a. This provides idle lift. i.e., allows the tab body 99 to be pivoted relatively easily to the position shown in FIG. 8a without rupturing the score line 91. Idle lift is advantageous in allowing the user to get his finger beneath the lifting end 105. The tab 95 also has a double layer reinforcing section 109 substantially as described hereinabove with reference to FIGS. 1-3.

In operation of the easy opening container wall 85, the lifting end 105 of the tab 95 is moved away from the can end 87 and during idle lift such movement of the handle'end is substantially unrestrained. Following idle lift the nose end 107 bears on the region of the can end 87 outside of the tear portion 93 and is given relatively rigid support with the result that an upward lifting force is applied to the leading end of the tear portion 93' through the connecting wall 103, the attachment portion 101 and the rivet 97. By continuing such pivotal movement of the tab body 99, the sheet material of the score line 91 at the leading end of the tear portion 93 will be ruptured. A portion of the tab covers the area of initial opening to deflect spray of the contents. Following such initial rupture, the user exerts an outward pulling force on the tab body 99 to thereby completely sever the tear portion 93 from the container wall 87 to form a pouring opening.

FIG. 9 shows a tab 121 of somewhat different construction than the tabs illustrated in FIGS. l-8. The tab 121 includes a tab body 123 and an attachment portion 125 integrally joined to the tab body by a connecting wall 127 (FIG. 10). The connecting portion has an arcuate cutout 128. The tab 121 is preferably integrally formed of sheet material such as aluminum and the tab body 123 surrounds the attachment portion 125. The tab body 123 defines an opening 129 sized to accommodate the finger of a user. The tab body 123 is relatively longitudinally rigid and includes a lifting end 131 and a rupturing or nose end 133.

The tab body 123 is of less rounded appearance than the tab body 29 (FIG. 4). The tab body 123 has an inner reinforcing head or curl 135 and an outer reinforcing bead or curl 137 which is interrupted at the lifting end 131 and at the nose end 133 by a rupturing flange 139. The rupturing flange 139 differs from the rupturing point 53 (FIG. 4) in that the outer bead 133 is severed along lines 141 and 143 (FIG. 11) to thereby free the sides of the flange 139 so that it is connected to the remainder of the tab only along the upper end thereof. The outer bead 133 also includes a double layer portion 145 which supports the outer surface 147 of the connecting wall in the same manner described hereinabove with reference to FIGS. 3 and 4. The outer bead 137 is cut along a radial line 149 at the nose end 133 as shown in FIG. 9. Accordingly, the tab 121 is very similar to the tab 23 shown in FIGS. 3 and 4 except that the former provides a rupturing flange 139 in lieu of the integral rupturing point 53 of the former.

FIGS. 10 and 12 show an easy opening container wall 151 utilizing the tab 123, it being understood that the The panel 161 covers a major portion of the area in plan of the can end 153 and has a secondary scoreline 163 therein closely adjacent and spaced radiallyinwardly from-the primary score line 159. The secondary score line 163 constitutes an anti-fracture score which permits the segment of the panel16l circumscribed thereby to flex if the container is dropped to thereby prevent such impact from rupturing the primary score 159. Except for a section 165 of the score line 163, the score line 163 is spaced a constant radial distance from the primary score line 159. Thus, except for the section 165, the secondary score line 163 is geometrically similar to the score line 159.

The tab 123 is attached to the panel 161 by .a rivet 167 formed integrally with the panel with the rivet 167 projecting through an aperture 169 of the attachment portion 125. The tab 123 is oriented radially of the panel 161 with the lifting end 131 being at an inward position and with the rupturing flange 139 overlying a location on the primary score line 159. Such orientation is maintained by a dimple 168 integral with the panel 161 which projects into the arcuate cutout 128 of the tab 121. The panel 161 has an upstanding integral rib 170 to space the lifting end 133 above the panel.

In the embodiment of FIGS. 9-12, the rupturing flange 139 projects generally perpendicular relative to the panel 161. The thickness of the rupturing flange 139 is greater than the width of the primary score line 159 and a portion of the rupturing flange 139 overlies the can end 153 outside of the panel 161. Upon raising of the lifting end 131, the tab body 123 pivots generally about a pivot axis 171 lying on or closely adjacent the region of contact between the connecting wall 127 and the double layer portion 145. This forces the rupturing flange 139 downwardly towards the can end. In addition, the rupturing flange 139 travels back, i.e., toward the central region of the panel 161 somewhat. The rupturing flange 139 tends to interlock with the primary score line 159. As pivotal movement of the tab body 123 continues, the tip of the rupturing flange 139 tends to remain interlocked with the score line and to bend as the remainder of the rupturing flange travels back somewhat more. Ultimately, the rupturing flange 139 applies sufficient force to the sheet material along the primary score line 159 to rupture the same and thereafter further pivotal movement of the tab body 123 causes inward bending of the panel 161 generally along the section 165 of the secondary score line 163 substantially as described above with reference to FIGS. 1-6. After initial severance of the score line 159, the bending of the panel 163 and of the tab body 123 about different hinge lines may cause some additional bending of the rupturing flange 139 assuming that the latter remains interlocked with the sheet material along the ruptured primary score line 159.

FIGS. 13 and 14 illustrate the effect of changing the location at which the connecting wall is supported on the amount of travel back of the rupturing flange. FIGS. 13 and 14 show tabs 121a and 121b, respectively. each of which is identical to the tab 121 (FlGS. 9l2) except as specifically noted herein. Similarly FIGS. 13 and '14 show can ends 153a and 15312, respectively, which are identical to thecan end 153 (FIG. 12) except as specifically noted herein. Parts of FIGS. 13 and 14 corresponding to parts of FIGS. 9-12 are designated by corresponding reference numerals followed by the letters a and b, respectively.

The tab 121a has a tab body 123a and an attachment portion 135a, the latter being attached toa panel 161a by a rivet 167a integral with the panel 161a. The tab 121a also has a connecting wall 127a and a rupturing flange 139a which is oriented relative to the primary score line 159a substantially as described in connection with FIGS. 912. The-tab 121a has a double layer portion or reinforcing section 1450 which engages the ots about the hinge line 171a which is higher up on the connecting wall 127a than is the hinge line 171. This has the effect of moving the hinge line 171a further away from the section 165a of the secondary score line and from the panel 161a thereby tending to increase travel back. Accordingly, the travel back of the rupturing flange 139a is greater than the travel back of the rupturing flange 139 (FIG. 10).

The tab 121b is identical to the tab 121 except that the reinforcing section l45b engages the connecting wall 127]) at a lower point thereby forming a relatively low hinge line 171b. The panel 161]) is identical to the panel 161a except for the formation of an upwardly opening rib 173 which receives a portion of the reinupper end of the connecting wall 127a. Thus, while the reinforcing section 145 (FIG. 10) engages a central portion of the connecting wall 127, the reinforcing section 145a engages the connecting wall 127a as high up on the connecting wall as the dimensions of the components of the tab 121a will permit. This causes the tab to be pivotable about a hinge line 171a which lies near the upper end of the connecting wall 127a.

The operation of the tab 121a is the same as the operation of the tab 121 except that the tab body 123a pivforcing section 14511 to thereby permit the latter to engage the connecting wall 127b at a lower region than would be possible if the rib 173 were not formed in the panel 161b.

The tab l21b operates in the same manner as the

tabs

121 and 121a except that the hinge line 17lb is lower relative to the panel 16112 and closer to the section 165b of the secondary score line to thereby reduce travel back of the rupturing flange 13%. The rib 173 preferably is somewhat longer than the reinforcing section l45b and is dimensioned so as to loosely receive the portion of the reinforcing section which is positioned therein.

Although exemplary embodiments of the invention have been shown and described, many changes, modifications and substitutions may be made by one having ordinary skill in the art without necessarily departing from the spirit and scope of this invention.

l claim:

1. A method of making a tab of the type attachable to an easy opening container wall to initiate severance of a segment of the container wall wherein said tab includes a body having a lifting end movable away from the container wall andan attachment portion for fastening to the container wall and means defining an opening to accommodate a users finger, said method comprising: providing a strip of sheet material,

forming in said strip a tab blank having a body and an inner and outer peripheral surface, said tab blank being integrally connected to said strip by web means at a junction located at that portion of the blank formable into the lifting end of said tab, forming an inner curl on the inner peripheral surface of said blank to protect the users finger from laceration, forming an outer curl on the outer peripheral surface of said blank which is continuous along the longitudinal sides of the tab body, said outer curl in the region of said web means including portions adjacent to but spaced from said web means, and severing said web means at the junction of said body so that the line of severance is recessed towards said body whereby said adjacent portions of said outer curl prevent contact between a users finger and said line of severance.

'2. A method as defined in claim 1 wherein said inner and outer curls are bent over to form a double layer of sheet material.

3. A method as defined in claim 1 wherein a rupturing element is formed on the portion of the tab blank removed from said lifting end.

4. A method as defined in claim 3 wherein said rupturing element is formed by shaping said outer curl.

5. A method as defined in claim 3 wherein said rupturing element is formed by interrupting the outer curl to form a rupturing flange.

6. A method as defined in claim 1 wherein said strip is advanced through several stations and wherein said tab blank is carried on said strip solely by said web means.

7. A method as defined in claim 6 wherein said web means is located generally centrally of the lifting end of said tab blank.

8. A method as defined in claim 1 wherein a notch is formed in that portion of the tab blank formable into the lifting end of the tab, and said web means being located in the area of the notch and constituting the sole support between said strip and said tab blank for all subsequent operations on said tab blank.

9. A method as defined in claim 8 wherein said outer peripheral curl is interrupted by said notch, and wherein the line of severance-of said web means is adjacent to said body whereby the portion of said outer peripheral curl is adjacent to said notch and operates to prevent contact between a users finger and the line of severance.

l0. A method as defined in claim 1 wherein said strip is an elongated strip of sheet material.

11. A method as defined in claim 1 wherein said inner and outer peripheral surfaces are formed sequentially.

12. A method as defined in claim 1 wherein said inner curl is formed by turning the sheet material along the inner periphery outwardly, and the outer curl is formed by turning the sheet material along the outer periphery inwardly.

13. A method as defined in claim 1 wherein an attachment portion is formed in said opening, and wherein said inner curl is continuous except in the area of said attachment portion.

14. A method of making a tab of the type attachable to an easy opening container wall to initiate severance of a segment of the container wall wherein the tab has an outer curl extending along the outer periphery of the tab and a lifting end movable away from the container wall to initiate severance of said segment, said method comprising:

providing a section of sheet material;

severing the sheet material to form a tab blank with the tab blank being integrally connected to the section of sheet material by a web of the sheet material and with the tab blank being completely severed from the section of sheet material except for said web;

deforming the tab blank to form said tab with the tab being integrally connected to said section of sheet material by said web and with said web being at said lifting end and at least partially interrupting said outer curl; and

severing said web to separate the tab from the section of sheet material,

said line of severance being recessed whereby adjacent portions of the outer curl extend outwardly beyond the line of severance.

15. A method as defined in claim 14 wherein said web is located generally centrally of the lifting end of the tab.

16. A method as defined in claim 14 wherein said section is an elongated strip of sheet material, said step of deforming and said last mentioned step of severing are carried out at first and second stations, respectively, said method including moving the strip so that the tab moves from said first station to the second station with the web carrying the tab in the strip between said stations.

Claims

1. A method of making a tab of the type attachable to an easy opening container wall to initiate severance of a segment of the container wall wherein said tab includes a body having a lifting end movable away from the container wall and an attachment portion for fastening to the container wall and means defining an opening to accommodate a user''s finger, said method comprising: providing a strip of sheet material, forming in said strip a tab blank having a body and an inner and outer peripheral surface, said tab blank being integrally connected to said strip by web means at a junction located at that portion of the blank formable into the lifting end of said tab, forming an inner curl on the inner peripheral surface of said blank to protect the user''s finger from laceration, forming an outer curl on the outer peripheral surface of said blank which is continuous along the longitudinal sides of the tab body, said outer curl in the region of said web means including portions adjacent to but spaced from said web means, and severing said web means at the junction of said body so that the line of severance is recessed towards said body whereby said adjacent portions of said outer curl prevent contact between a user''s finger and said line of severance.

2. A method as defined in claim 1 wherein said inner and outer curls are bent over to form a double layer of sheet material.

9. A method as defined in claim 8 wherein said outer peripheral curl is interrupted by said notch, and wherein the line of severance of said web means is adjacent to said body whereby the portion of said outer peripheral curl is adjacent to said notch and operates to prevent contact between a user''s finger and the line of severance.

10. A method as defined in claim 1 wherein said strip is an elongated strip of sheet material.

14. A method of making a tab of the type attachable to an easy opening container wall to initiate severance of a segment of the container wall wherein the tab has an outer curl extending along the outer periphery of the tab and a lifting end movable away from the container wall to initiate severance of said segment, said method comprising: providing a section of sheet material; severing the sheet material to form a tab blank with the tab blank being integrally connected to the section of sheet material by a web of the sheet material and with the tab blank being completely severed from the section of sheet material except for said web; deforming the tab blank to form said tab with the tab being integrally connected to said section of sheet material by said web and with said web being at said lifting end and at least partially interrupting said outer curl; and severing said web to separate the tab from the section of sheet material, said line of severance being recessed whereby adjacent portions of the outer curl extend outwardly beyond the line of severance.