Pull tab for readily openable can lid

A pull tab rivetted to an opening piece defined by a score provided on the lid of a can containing refreshing drink. The pull tab integrally comprises panel portion having a rivet hole, leg portions on the opposite sides of the panel portion and a ring portion contiguous to the ends of the leg portions and remote from the panel portion. The ring portion includes an inner peripheral fold-up and an outer peripheral fold-up and the leg portions include side edge fold-ups and reinforcing fold-ups contiguous to the extreme edges of the side edge fold-ups.

BACKGROUND OF THE INVENTION 
This invention relates to pull pieces or pull tabs adapted to be removably 
attached to the lids of various cans containing refreshing drinks for 
readily opening the cans allowing the user to drink the contents. 
Most conventional cans containing refreshing drinks have a pull piece or 
pull tab 20 removably attached by means of a rivet 18 to an opening piece 
15 defined by a cut line or score 16 provided on the lid 10 of a can, as 
shown in FIG. 7, which allows for removal of the opening piece 15 by 
pulling the pull tab 20 up, thus enabling the user to drink the contents 
of the can. 
As shown in FIG. 8, the conventional pull tab 20 integrally comprises a 
panel portion 25 having a rivet hole 26 therein, left-and right-hand leg 
portions 22, 22 formed on and connected to the opposite sides of the panel 
portion 25 by means of an intermediate semi-circular ramp and a ring 
portion 21 contiguous to the ends of the leg portions 22, 22 and remote 
from the panel portion 25. 
The inner peripheral edge of the ring portion 21 is folded back outwardly 
to form an inner peripheral fold-up 31 and the outer peripheral edge of 
the ring portion 21 is also folded back inwardly in the opposite direction 
from the inner peripheral fold-up 31 to form an outer peripheral fold-up 
32. The outer side edges of the left- and right-hand leg portions 22, 22 
are also folded back inwardly or in the same direction as the outer 
fold-up 32 of the ring portion 21 to form side edge fold-ups 33, 33 which 
are contiguous to the outer fold-up 32 at the outer peripheral edge of the 
ring portion 21. 
When the inner and outer peripheral fold-ups 31, 32 of the ring-portion 21 
and the outer side edge fold-ups 33 of the leg portions 22 are formed by 
folding the blank for the pull tab 20, the severed edges of the pull tab 
20 which remain sharp as the blank of the pull tab is stamped out of a 
piece of sheet metal are rounded, as shown in FIG. 9, whereby the pull tab 
providds a safeguard to the user and rigidity is imparted to the pull tab. 
However, in order to impart the pull tab 20 with a rigidity sufficient for 
tearing the opening piece 15 off the can lid 10 so as to allow the 
contents of the can to be drunk the conventional pull tab 20 has to be 
formed of thick sheet metal having a thickness on the order of 0.36 mm, 
which makes it difficult to reduce the thickness of the pull tab as 
desired. 
SUMMARY OF THE INVENTION 
Thus, according to the present invention, the pull tab is formed of sheet 
metal which is thinner than that for the conventional pull tabs and as a 
result, the pull tab of the invention can be easily processed and the 
meterial cost can be cut down, whereby the overall production cost of the 
pull tab is less. 
According to the present invention, a pull tab for a readily openable can 
lid is provided which integrally comprises a panel portion having a rivet 
hole therein, left-and right-hand leg portions formed on and connected to 
the opposite sides of the panel portion by means of an intermediate 
semi-circular ramp, and a ring portion contiguous to the ends of the leg 
portions and remote from the panel portion, said ring portion having an 
inner peripheral fold-up and an outer peripheral fold-up and said legs 
having outer side edge fold-ups whereby the severed edges of the pull tab 
are rounded and reinforced, and which is characterized by the fact that a 
reinforcing fold-up is provided extending from the end of each of the leg 
portions remote from the ring portion or the line connecting the center of 
the rivet hole in the panel portion and the outer side edge fold-up 
associated with each of the leg portions remote from the ring portion to a 
point where the inner peripheral fold-up of the ring portion diverges from 
the outer side edge fold-up associated with each of the leg portions 
whereby the pull tab is reinforced at least in the portion thereof 
extending from the end of each of the leg portions remote from the ring 
portion to the above-mentioned point of divergence. 
By the provision of the reinforcing fold-up which extends at least from the 
line connecting the center of the rivet hole in the panel portion and the 
outer side edge fold-up of each of the leg portions to a point where the 
inner peripheral fold-up diverges from the outer side edge fold-up of each 
of the leg portions as mentioned hereinabove, when the pull tab is pulled 
up to tear the opening piece off the can lid to open the can, the leg 
portions of the pull tab can be effectively prevented from bending at 
areas adjacent to the side of the panel portion facing the ring portion to 
thereby reinforce the pull tab at strategic areas thereof. 
The above and other objects and attendant advantages of the present 
invention will be more readily apparent to those skilled in the art from a 
reading of the following detailed description in conjunction with the 
accompanying drawings which show preferred embodiments of the invention 
and a prior art, respectively, for comparison purposes.

PREFERRED EMBODIMENT OF THE INVENTION 
The respective parts of the embodiments of the present invention have 
affixed thereto the same numerals as those used for the corresponding 
parts of the prior art as shown in FIGS. 8 and 9. 
Referring to FIG. 1 wherein the first embodiment of the present invention 
is shown, in the pull tab 20, a reinforcing fold-up 34 is contiguous to 
the inner side edge of the outer side edge fold-up 33 of the associated 
leg portion 22 and extends from the point 38 where the inner peripheral 
fold-up 31 of the ring portion 21 diverges from the fold-up 33 of each of 
the leg portions 22 to the horizontal line 37 intersecting the 
longitudinal axis of the pull tab 20 at right angles thereto and 
connecting the center of the rivet hole 26 and the outer side edge fold-up 
33 of each of the leg portions 22. 
As more clearly shown in FIG. 2, the blank 29 for the pull tab 20 is 
stamped out of a piece of sheet metal so as to provide outwardly extending 
projections 35 on the opposite sides of the pull tab blank 29 and the 
projections 35 are bent towards the associated leg portion 22 into 
different configurations such as L-, S- and curled shapes, respectively, 
as shown in FIGS. 3 to 5 inclusive, to provide the reinforcing fold-ups 
34. 
In the conventional pull tab 20 as described hereinabove, the outer side 
edge area of each leg portion 22 has a simple double construction with the 
outer edge area folded down to provide the fold-up 33 as shown in FIG. 9. 
In contrast with the conventional pull tab, according to the present 
invention, the leg portions 22 on the opposite sides of the side 39 of the 
panel portion 25, where the applied stress concentrates when the pull tab 
is pulled up for tearing the opening piece 15 off the can lid, are folded 
back at the outer side edges of the leg portions to provide the fold-ups 
33 and the extreme edges of the fold-ups 33 are further folded back 
towards the associated leg portions 22 into L-, S- and curled 
configurations, respectively, in order to provide reinforcing fold-ups 34 
and thereby to increase the rigidity and resistance against bending of the 
leg portions 22. 
In FIG. 3A, the reinforcing fold-up 34 extends from the extreme edge of the 
associated fold-up 33 at right angles thereto and abuts against the 
associated leg portion 22, in FIG. 3B, the reinforcing fold-up 34 extends 
from the extreme edge of the associated fold-up 33 in a curled 
configuration and abuts against the associated leg portion 22, in FIG. 3C, 
the reinforcing fold-up 34 extends from the extreme edge of the associated 
fold-up 33 at right angles thereto and terminates short of the associated 
portion 22, and in FIGS. 3D and 3E, the reinforcing fold-ups 34 extend 
from the extreme edges of the associated fold-ups 33 in different 
substantially S-shaped configurations and abut against the associated leg 
portions 22, respectively. 
FIGS. 4A, 4B, 4C, 4D and 4E show different triple reinforcing arrangements. 
Each of the triple reinforcing arrangements. Each of the triple 
reinforcing arrangements is obtained by stamping the blank for the pull 
tab out of a piece of sheet metal so that the projections 35 have a 
greater width on the opposite sides thereof and folding the projections 
down as shown in these Figures. In FIG. 4A, the reinforcing fold-up 34 
extends from the extreme edge of the associated fold-up 33 first at right 
angles thereto and then in parallel to and spaced from the associated leg 
portion 22 and fold-up 33, in FIG. 4B, the reinforcing fold-up 34 extends 
from the extreme edge of the associated fold-up 33 first at an upwardly 
sloped angle and then sloping downwardly to abut against the associated 
fold-up 33, in FIG. 4C, the reinforcing fold-up 34 extends from the 
extreme edge of the associated fold-up 33 first horizontally in contact 
therewith and then uprightly to abut against the associated leg portion, 
in FIG. 4D, the reinforcing fold-up 34 extends from the extreme edge of 
the associated fold-up 33 first at right angles thereto, then horizontally 
in contact with the associated leg portion 22 and finally downwardly at 
right angles to the leg portion 22 and fold-up 33 to abut against the 
latter, and in FIG. 4E, the reinforcing fold-up 34 extends from the 
extreme edge of the associated fold-up 33 in a substantially S-shaped 
configuration and abuts against the associated leg portion. 
FIGS. 5A and 5B show two types of quadruple reinforcing arrangements. As 
will be apparent, the blanks for the pull tabs of these Figures have 
projections 15 greater than those on the blanks for pull tabs in FIG. 4 
with respect to width. In FIG. 5A, the reinforcing fold-up 34 extends from 
the extreme edge of the associated fold-up 33 in a substantially L-shaped 
configuration with the longer and shorter legs of the L-shape in contact 
with the associated leg portion 22 and fold-up 33, respectively and in 
FIG. 5B, although the reinforcing fold-up 34 extends from the extreme edge 
of the associated fold-up 33 in a substantially L-shape, the longer and 
shorter legs of the L-shape are in contact with the fold-up 33 and leg 
portion, respectively. 
When the reinforcing fold-up forming projections 35 do not extend from a 
position adjacent to the horizontal line 37 passing through the center of 
the rivet hole 28, but extend from the ends 23 of the leg portions 22, 22 
remote from the ring portion 21 to a position adjacent to the point 38 
where the fold-up 31 on the ring portion diverges from the fold-up 33 of 
each of the leg portions, as shown on FIG. 9, the blank has a simpler 
shape, which makes it easy to stamp the blank out of a piece of sheet 
metal and fold the blank to form the fold-ups 33 and reinforcing fold-ups 
34. 
The pull tab 20 of the invention is not limited to the linear shape at the 
panel portion end as shown in FIG. 1, but may, within the scope of the 
invention, be arcuate also at that end. In such as case, the panel portion 
25 is circular in shape (FIG. 9). 
The operation of the pull tab 20 will now be described, referring to FIG. 
10. When the pull tab is pulled up to tear the opening piece 15 off along 
the score 16, the pull tab acts as a lever with the point of force at the 
ring portion 21, the fulcrum at the ends 23 of the leg portions 22 and the 
point of operation at the rivet hole 26. The force applied to the ring 
portion 21 as the pull tab is pulled up for tearing the opening piece 15 
off along the score 16 so as to open the can lid is transmitted to the 
rivet 18, from where the force is transmitted to the score 16 such as to 
cut through the same. 
In the pull tab 20 acting as a lever in this way, most of the applied 
stress is concentrated in an area adjacent to the side 39 of the panel 
portion 25. 
Thus, the leg portions 22 frequently bend on the side 39 of the panel 
portion 25 which not only makes it difficult to open the can, but also 
causes the pull tab 20 to slip off the rivet 18 to such an extent that 
opening of the can becomes impossible. 
In order to prevent the leg portions 22 from bending, according to the 
present invention, the reinforcing fold-ups 34 are provided on the 
fold-ups 33 of the leg portions 22 extending from a position adjacent to 
the horizontal line 37 passing through the center of the rivet hole 26 to 
a position adjacent to the point 38 where the inner peripheral fold-up 31 
of the ring portion 21 diverges from the fold-up 33 of each of the leg 
portions 22 so that the leg portions 22 are reinforced at areas adjacent 
to the side 39 of the panel portion 25 where most of the applied stress is 
concentrated. 
As mentioned hereinabove, according to the present invention, in order to 
cover the side 39 of the panel portion 25 where most of the applied stress 
is concentrated when the can is opened, the reinforcing fold-ups 34 are 
formed on the leg portions 22 extending from a position adjacent to the 
horizontal line 37 passing through the center of the rivet hole 26 in the 
panel portion 25 to a position adjacent to the point 38 where the inner 
peripheral fold-up 31 on the ring portion 21 diverges from the fold-ups 33 
on the leg portions 22 so as to impart rigidity to the pull tab in 
accordance with a particular stress distribution. Thus, the pull tab of 
the present invention may be formed of 0.30 mm thick sheet metal which is 
thinner than the conventional pull tab formed of 0.36 mm thick sheet 
metal. Since the pull tab 20 of the invention (FIG. 1) is formed by 
stamping the blank 29 off a piece of sheet metal so as to provide the pull 
tab with the reinforcing fold-ups 34, material costs can be reduced. In 
addition, since the blank is formed of thin sheet metal, the blank can be 
easily bent so as to form the inner and outer peripheral fold-ups 31, 32 
on the ring portion 21 and the fold-ups 33 on the leg portions 22 and 
thereby to enhance the production efficiency of the pull tab 20. 
While only two embodiments of the invention have been shown and described 
in detail, it will be understood that the same are for illustration 
purposes only and not to be taken as a definition of the invention, 
reference to the appended claims being available for this purpose.