Tabs for easy-open can end

A tab for use with an easy-open can end, which is made free from any protrusion with a cut edge thereon that would otherwise contact a finger or a lip of the user without a increasing the number of manufacturing steps to complete the tab. A tab having a body, a nose end with a tip, an opposite grip end, and an island formed within the tab body and attached to the nose end along a hinge, the island including a rivet hole for receiving a rivet on a can end panel to attach the tab to the end panel. The tab body is joined to a carrier strip, from which the tabs are made, by a joint formed in a tab making process. In a tab severing process, the joint is cut off to sever the tab from the strip, leaving a protrusion on the tab with a cut edge. The tip of the nose has a gap into which the protrusion can be bent or curled, to guard the cut edge, as the tab is moved to attach the island to the end panel with a rivet. When the tab is lowered in the downward passage, the swing arm moves to cause the curling surface to press the tab and curl the protrusion onto the tab.

CROSS REFERENCE TO RELATED APPLICATION 
This application is related to U.S. patent application Ser. No. 08/792895 
filed Jan. 31, 1997, now U.S. Pat. No. 5,741,105 entitled METHOD OF AND 
APATUS FOR MANUFACTURING TABS FOR EASY-OPEN CAN END. 
FIELD OF THE INVENTION 
The present invention relates to a tab secured to an upper surface of an 
easy-open can end for opening a tear panel in the can end when the tab is 
lifted. 
BACKGROUND OF THE INVENTION 
Easy-open can ends, which can be opened by lifting and pulling tabs mounted 
thereon, used on cans for containing beverages, etc., are well known in 
the art. In recent years, retained tab easy-open can ends which keep the 
tab attached to the end panel after they are opened, have been the 
predominant type. Specifically, the retained tab easy-open can end has an 
integral rivet projecting upwardly from the end panel, an openable area or 
tear panel surrounded by a score line which is of a partly discontinuous 
annular shape, and an operating tab fixed to the end panel by a tongue 
which has a rivet hole that receives the rivet. The tab includes a tip end 
positioned over a part of the tear panel, and a grip ring disposed on its 
rear end remote from the tip end. When the grip ring of the tab is lifted 
off the end panel, the tip end of the tab presses a region of the openable 
area, transferring an upward force to the front edge of the rivet, and 
causing the initial breaking or "pop" of the score. Continued lifting of 
the tab then causes the tab to pivot at the rivet island hinge applying 
continued force on the nose to complete the tear panel opening. 
A tab for use on such a retained tab easy-open can end is typically 
manufactured as follows. First, a tab blank, which is larger than an 
actual finished tab, is blanked out of a strip of metal that is unreeled 
from a metal strip coil. It should be noted the completed tab is not 
totally detached from, but remains partly joined to, the strip by a joint 
or "carry strip" until such time as the tab is attached (staked) to an end 
panel. Next, the tab blank is punched with grip holes for incremental 
feeding of the strip and attached tabs, and with holes which are used in 
forming a tongue, a rivet hole, and a grip. Thereafter, the tab blank is 
formed with a predetermined pattern of convex and concave shapes, and 
curled (for improved rigidity) along its peripheral edge into a final tab 
profile. The joint is then severed to separate the tab from the strip, 
while the tab is fixed to a rivet on a can end through the rivet hole in 
the tongue. 
When the tab is severed from the strip, a protrusion is left at a cut edge 
of the severed joint projecting from an outer edge of the tab. In beverage 
can end tabs the joint is often positioned on the grip end of the tab, and 
thus a protrusion is formed on the grip end when the joint is severed. 
When the grip end of the tab is lifted by a finger, a sharp cut edge of 
such protrusion tends to contact the finger, making the user feel 
uncomfortable. If, on the other hand, the joint is positioned on the nose 
end of the tab (as more often used on tabs for full panel ends on food 
cans), then the protrusion is formed on the tip end of the tab nose when 
the joint is severed. Heretofore, when this type of "nose carrier" tab is 
used on beverage cans, when can end is opened the pouring aperture may 
contact a lip of the user, and the sharp cut edge of the protrusion is 
liable to come into contact with the lip, also making the user feel 
uncomfortable, perhaps catching on facial hair or scratching the user. 
There are, however, some advantages to using a nose carrier attachment 
between the tabs and the metal carrier strip from which the tabs are 
formed. 
Consequently, it has been proposed to manufacture a tab according to such 
proposed method but such proposal requires a stage for forming a special 
joint in addition to a stage for cutting off the joint at the end close to 
the strip. If one considers the scoring of the carry strip an additional 
station (usually in the die bridge) is needed. In general, it is quite 
difficult, if not impossible, to get a punch and opposing die close to the 
edge of the tab. Thus, current pinch score techniques have been tried, 
followed by breaking the tab out of the skeleton over cut off knives, but 
this approach encounters problems of controlling score depth. If a score 
is too deep, this can tear up thin tabs or cause premature break outs or 
defects of metal properties on specifications. All these can lead to 
difficulties in running of can end conversion equipment in which the tab 
forming and attaching (staking) features are incorporated. Further, an 
unsupported rivet island requires less forming stations but has 
disadvantages of producing higher opening (pop) forces, less tab bends 
(the number of successive bends at the tab/island connection before the 
tab breaks off), and requiring heavier gage material for the same tab 
strength, as compared to a tab with a structure having a rivet island 
support. 
Other problems of attaching the tab in one continuous staking motion create 
critical timing of tab attaching and rivet head formation, which require 
in some applications a pre-stake operation and then final clinch. Thus, 
for practical reasons the current tab types avoid having a nose carrier. 
Another factor to be considered is that in use operation forces on a tab of 
the retained (ecology) type during its opening or operating cycle can 
cause side loads on the tab nose that tend to turn the tab, reducing 
opening margin. Additionally, accidental turning of the tab prior to 
commencing the opening cycle can cause the end to fail to open. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a retained tab for an 
easy open can end, which tab when attached to and end panel, is free from 
any protrusion thereon that would otherwise contact a finger or a lip of 
the user. Such tab is uniquely adapted to the method and apparatus which 
is the subject of the related application. 
To achieve the above object, there is provided in accordance with the 
present invention a tab for use with an easy-open can end, which tab is 
fixed to an end panel by an integral rivet and is capable of opening the 
can end by tearing an openable area (pour panel) surrounded by a score on 
the end panel when the tab is lifted. The tab has an island with a rivet 
hole which receives the rivet and also has a grip end, such as a grip 
ring, the tab being joined at its nose to a strip from which the tab is 
blanked. The joint is severed to free the tab from the strip. The severing 
operation comprises positioning a tab, still attached to the strip, in a 
tab severing position, cutting off the joint thereby to sever the tab from 
the strip, and lowering the released tab, which has formed with a 
protrusion at the tab nose having a cut edge where the joint has been 
severed. 
In this operation, the tab is held against horizontal movement, and the 
protrusion on the tab nose is contacted by a curved curling surface on a 
free (distal) end of a swing arm, which arm has an anchored (proximal) end 
pivotally supported on a side of a downward passage in which the tab is 
lowered. The swing arm is moveable in the downward passage, and is 
normally urged to swing upwardly by a spring means. Swinging motion of the 
swing arm as the tab is lowered presses the curling surface against the 
protrusion to curl the protrusion on the tab back against the tab nose. 
The tab is attached to the end panel by further lowering the tab following 
the tab severing step, and after the swing arm has moved past the pressing 
position, releasing the swing arm from abutment against the tab and 
allowing the arm to swing upwardly under the bias of the spring means. 
Then the rivet hole in the tab is placed over the rivet on an end panel 
supported in the position to which the tab is lowered, and the rivet is 
compressed (staked) thereby fixing the tab to the end panel. 
According to the present invention, the joint between the strip and the tab 
can be cut off, close to the tab nose and the protrusion can be curled 
into a gap left in the tab tip, in a sequence of steps carried out by the 
tab severing apparatus as it lowers the tab from the tab severing position 
at which the tab is severed from the strip. 
Specifically, in the tab severing apparatus, the tab lowering means is 
moved toward a tab on the strip which is positioned in the tab severing 
position. At the same time, the joint is cut close to the tab nose by the 
cutter of the severing means which moves toward the joint in synchronism 
with the tab lowering means. The tab is severed from the strip, and a cut 
edge of the joint remains as a protrusion on the tab nose. Since the 
protrusion with its sharp cut edge could make the user feel uncomfortable 
when contacting the edge with a finger or a lip, the protrusion is curled 
back onto the tab. As explained in the related application, following the 
above descent of the tab, the tab is further lowered by the tab lowering 
means until the protrusion is engaged by the curling surface of the swing 
arm which is positioned below the tab severing position. 
The protrusion, and specifically its cut edge, is now curled back onto the 
tab preferably into the gap, and into a shape which will not contact a 
finger or a lip of the user. Since the protrusion is curled onto the tab 
immediately after the tab is severed from the strip, the tab can be 
manufactured without an increase in the number of manufacturing steps. 
Thus, with design of tab provided by the invention, and particularly its 
tip or nose portion, the remaining protrusion at the tab nose can be 
curled onto the tab and the tab can be attached (riveted or staked) to the 
end panel all at one existing operating station. Stated another way, the 
nose strip severance, and curling of the remaining protuberance into a 
guarded location upon descent of the tab from the severing position, is 
achieved at the attaching and riveting station. Consequently, the tab can 
be manufactured efficiently by a simple apparatus arrangement without the 
need for additional working stations in the tab tooling. 
The tongues, which form the nose of the tab and the nose tip cavity into 
which the protrusion can be moved, additionally have double folded ends 
which are located under the hinge connection of the island to the 
remainder of the tab so as to locate the axis of the tab tilting motion at 
a elevation with respect to the island and end panel, which enhances the 
continuous action of the tab nose to open the our panel, and this in turn 
reduces the force necessary for the tab to produce such necessary result. 
Furthermore, the island of the tab is located securely against the end 
panel around the integral rivet when the rivet is staked, and the island 
is provided with an anti-rotation feature which maintains proper alignment 
of the tab and particularly its nose to minimize failed openings. 
Other objects and advantages of the invention will be apparent from the 
following description, the accompanying drawings and the appended claims.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
A tab 1 manufactured according to the embodiment of the present invention 
is suitable for use on a stay-on tab easy-open can end. As shown in FIG. 
1, the completed can structure comprises a disk-shaped end panel 3 and the 
operating tab 1 mounted thereon, secured to a rim of can body 2. The end 
panel 3 has a rivet 4 by which the tab 1 is mounted on the end panel 3 and 
a score 6 which is of a partly discontinuous annular or loop shape and 
extends along and defines an openable area or pour panel 9 of the end 
panel 3. The tab 1 has an island or tongue 7 having a rivet hole 5 in 
which the rivet 4 is inserted. A grip 8 which may include a hole 8A 
located on a rear end of tab 1, and a tip end or nose 10 of the tab is 
positioned over pour panel 9 at a point where score line 6 is to be 
initially fractured. 
When the grip end 8 is lifted off end panel 3, nose 10 presses the pour 
panel 9, separating it along score line 6. At the end of such lifting 
action, pour panel 9 is bent toward the product side of the can end 2 and 
inward thereof about a discontinuous or hinge region of the score 6, 
thereby to open a pouring aperture in the can end. Island 7 is separated 
from the rest of the tab, except for a hinge connection 12, by a U-shaped 
gap 11. 
The sequence of manufacturing the tab 1 according to the embodiment of the 
present invention is illustrated in FIGS. 5-13. The tab as it is formed is 
shown inverted, e.g. the uppermost surfaces in section views FIGS. 6-13 
are surfaces which ultimately face the outer or public surface of end 
panel 3. Details are disclosed in the aforementioned related application; 
the tab 1 is formed by a tab forming process which uses tab tooling 
punches and dies, not shown. As shown in FIG. 5, tabs 1 are formed from a 
strip of metal S unreeled from a metal strip coil, the tabs are joined to 
the carrier strip by joints 13. More specifically, in the tab forming 
process as shown by the progressively illustrated results of the tool and 
die actions on the strip, the island or tongue 7 is blanked out of the 
strip 12 and a rivet hole 5 is punched in the island, nose tongues 14 on 
opposite sides of a joint 13 and forming the tip or nose end 10 are 
blanked out of strip S, and a hole 15 may be formed in grip end 8. The 
tips 16 of tongues 14 are bent back upon the tongues (see FIGS. 5, 6 & 7). 
Then, as shown at the top left part of FIG. 5, the outline or perimeter of 
a tab blank which is larger than the ultimate resulting tab, is blanked 
out of the strip S. 
Thereafter, as shown in FIGS. 5, 8, 9, 10 & 11, the nose tongues 14 are 
bent back over the nose and the peripheral edge of the tab blank is bent 
over into conformity with the shape of a tab 1. Now, the completed tab is 
formed, joined at its nose to the strip S by the joint 13. 
The strip, with tabs attached, is carried to a staking/attaching station in 
the main tooling of the apparatus for fixing tabs 1 to end panels 3. Then, 
as shown in the related application, a tab 1 is cut off the strip 12 in a 
tab severing process comprising a succession of steps, namely cutting 
joint 13, curling a resulting protrusion 13P (formed on tab nose 10 
between the folded over tongues 14 when joint 13 is severed) into the gap 
or space 18 between the tongues, and then placing the tab onto the rivet 4 
on an end panel, with the rivet projecting through the rivet hole 5. 
Finally, the rivet is staked to attach the tab to the end panel. 
The protrusion 13P is thus curled back into, and then guarded by, the nose 
of the tab, which is free from any protrusion that would otherwise contact 
a finger or a lip of the user. 
The underside of island 7 is located on a plane with the underside of the 
tab (see FIGS. 2, 4, 10 & 12), so the island will fit firmly against the 
end panel 3 as rivet 4 is staked. The extended oval hole 21 of the 
anti-rotation formation 20 in island 7 will engage around an oval bead 22 
in end panel 3, to resist any rotation of the tab once it is staked in 
place on the end panel. If desired, bead 22 can be formed in the end panel 
after staking of rivet 4. 
Also, the folded under (double folded) tips 16 of tongues 14 form a raised 
fulcrum for the hinge connection 8, providing better leverage for tab nose 
10 as it is pressed against score line 6 to achieve the initial break or 
"pop" of the score line. 
While the method herein described, and the form of apparatus for carrying 
this method into effect, constitute preferred embodiments of this 
invention, it is to be understood that the invention is not limited to 
this precise method and form of apparatus, and that changes may be made in 
either without departing from the scope of the invention, which is defined 
in the appended claims.