Full opening steel can end construction

A substantially full opening steel can end for food product cans easily opened by an aluminum pull tab riveted to a removable panel portion defined by a score line in a recessed end wall of the can end located close to a seam between the can end and can body. The panel portion has a protective triple fold formation along its peripheral edge when removed, and the score line is located in the top layer of the triple fold formation beneath an overlying stepped tip of the pull tab which ruptures the score line during opening of the can. The score line preferably extends 300.degree., 150.degree. in each direction from the stepped pull tab tip, around the can end to retain the opened panel portion and pull tab on the can when opened.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to food product cans provided with can end members 
which may be opened easily by tearing a panel portion of the end along a 
score line with a ring pull tab. More particularly the invention relates 
to such can ends fabricated from light gauge steel from which the torn 
panel portion when torn leaves a substantially full opening in the can 
end. The pull tab is riveted to the panel portion to be torn and is formed 
of aluminum. Tearing proceeds along the score line located in the steel 
end very close to a usual double seam which connects the can end to one 
end of a generally cylindrical steel can body. The score line preferably 
extends less than 360.degree., say 300.degree., around the can end 
adjacent the double seam, so that the torn panel portion remains connected 
with the can end at the opening thus formed with the pull tab connected 
thereto. 
Also, the invention relates to the described steel can end in which the 
periphery of the torn panel portion is formed with a protective triple 
fold generally of the type shown in U.S. Pat. No. 4,116,360 wherein the 
score line is located in the top triple fold layer, and the can end is 
initially ruptured on the score line by the nose or tip of a pull tab 
generally of the type shown in U.S. Pat. No. 4,042,144. 
In addition, the invention relates to the described steel can end with an 
aluminum pull tab riveted thereto having special rivet characteristics 
imparted during rivet formation combined with a specially shaped and 
located moustache type score adjacent the rivet to assist in ease of 
opening the can end without tearing the pull tab from the panel portion 
being torn from the can end when the can is being opened. 
Finally, the invention relates to a new steel can end construction 
described in detail below involving an interrelation of the forms, shapes, 
compositions, characteristics and cooperative arrangements of the various 
components combined to form the new can end. 
2. Description of the Prior Art 
Steel can ends for beverage cans are known having small teardrop- or 
keyhole-shaped pouring openings formed in the can end wall by pulling 
keyhole-shaped metal completely from the can end with a pull tab attached 
to the removed metal. 
Also, beverage cans are known which have pull tabs attached to torn 
teardrop metal portions, both of which remain attached to the can after 
forming the pouring opening. In general, the torn out metal portion 
remains inside the can and there is no protective edge formation on such 
torn metal portion inside the can. Some of such prior can ends may have 
been made from steel but it is exceedingly hard or difficult to open such 
steel can ends. 
Still another steel can end seamed to a steel can and provided with a steel 
pull tab having a so-called moustache cut behind the rivet is known. Such 
a can end is exceedingly hard and difficult to open. Such prior steel cans 
are intended to provide a full opening by completely tearing a panel 
portion from the can to form a full opening. The torn out panel portion 
has a protective edge formed by a peripheral triple fold. 
The score line in this prior device is located in the bottom layer of the 
triple fold below and concealed by the reversely bent two top triple fold 
metal layers. The panel portion to be removed extends from and in the 
plane of the top layer of the triple fold. Such particular score line 
location and triple fold arrangement in said prior device is believed to 
contribute among other matters to the great difficulty encountered in 
opening such a can end. Frequently, in attempting to open such prior 
device with the steel pull tab riveted thereto, the pull tab tears away 
from the can end leaving the can unopened. 
We are not aware of any prior art steel can end from which a full or 
substantially full opening panel may be very easily torn along an 
opening-defining score line with an aluminum pull tab riveted to the panel 
to be torn, and in which the torn panel portion has a protective triple 
fold formation along its torn edge. 
Accordingly, there is an existing need in the art for full opening cans 
provided with steel can ends which may be easily opened with an aluminum 
pull tab riveted to a full or substantially full opening panel portion by 
tearing along a score line located close to a seam between the can end and 
can body, and in which the torn panel portion has a protective triple fold 
formation along its peripheral edge. 
SUMMARY OF THE INVENTION 
Objectives of the invention include providing a new substantially full 
opening steel can end construction having a panel portion that may be torn 
easily from the can end along a score line with a pull tab riveted 
thereto; providing such new can end construction in which the torn out 
panel portion has a protective triple fold peripheral edge, in which the 
can end is formed from a particular type of light gauge steel, and in 
which the can end has a particular shape or contour in cross section; 
providing such new steel can end construction in which the pull tab is 
formed of aluminum that has a special stepped tip or nose cooperatively 
related to the can end contour and its triple fold formation which forms 
the protective edge when the panel portion is torn from the can end, and 
to the location of the score line defining the can opening when the panel 
portion is torn from the ean end; providing such new steel can end 
construction in which the score line formed in the can end is located 
close to the seam between the can end and can body and extends preferably 
short of 360.degree. around the can end to retain with the can the torn 
panel portion when torn from the can end along the score line; providing 
such new steel can end construction in which the score line is located in 
the upper surface of the top layer of the triple fold formation in the can 
end and has a critical residual dimension, that is metal thickness from 
the bottom of the V-shaped in section score line to the under surface of 
the thin metal scored, to permit on the one hand easy rupturing and 
opening of the can end, and to enable on the other hand the steel can end 
construction to qualify for required U.S.D.A. Drop Tests; providing such 
new steel can end construction with new rivet means connecting the 
aluminum pull tab to the steel can end characterized by dimensional 
requirements and modified steps of forming the rivet before staking it to 
the pull tab to obtain a satisfactory and efficient full overlap of the 
rivet metal integral with the can end when staking the pull tab to the can 
end; providing such new steel can end construction with a moustache cut 
score line cooperatively related to the new rivet means to encompass the 
rear rivet portion and to extend in the panel laterally outward of the 
side rivet portions and to terminate in curved extremities lying laterally 
in front of the front portion of the rivet means, said rivet-encompassing 
portion of the moustache cut located at the rear of the rivet being 
related to the location of the nose or top of the pull tab in front of the 
rivet; providing such new steel can end construction with the interrelated 
and cooperative relationship and arrangement of the various components of 
the can end and their characteristics, such that the pull tab may be in 
prestressed condition from the rivet to its tip when staked to the can 
end, and may be raised readily when grasped in a user's fingers to pop the 
moustache cut open, accompanied immediately by rupturing the score line 
beneath and by the pull tab tip as it wipes across the score line during 
continued leverage and raising of the pull tab, whereupon upward pull on 
the pull tab tears the panel portion along the score line at either side 
of the initially ruptured portion to a substantially full open position; 
and providing a new steel can end construction, formation and mode of 
operation in use which achieves the stated objectives and overcomes 
difficulties encountered in past attempts to provide easy opening, full 
opening steel can ends, in a reliable and effective manner, which can end 
construction is relatively inexpensive as compared with prior full opening 
triple fold protected aluminum can ends. 
These and other objectives and advantages may be obtained by the steel can 
end construction which may be stated in general terms as involving a metal 
can end of a type having a seam flange adapted to be connected by seam 
means to a food products can body and having a recessed corner located 
below the seam flange with an end wall extending inward from the recessed 
corner, and having a triple fold formation extending entirely around the 
end wall, with a score line located close to said recessed corner and 
extending around the end wall in the top layer of the triple fold defining 
a removable panel portion in the end wall, with the triple fold forming a 
protective peripheral edge on the panel portion when torn along the score 
line by an aluminum pull tab connected by a rivet formed integrally in the 
panel portion and located close to the score line, and with the removable 
panel portion of the end wall extending flatwise inward in the plane of 
the bottom layer of the panel portion protective peripheral triple fold 
formation, the pull tab having a flat nose bottom wall with an opening 
formed in its rear portion through which the rivet extends when the pull 
tab is staked to the removable panel portion and with a stepped tip formed 
at its front terminal portion and with its flat bottom wall held flatwise 
around the rivet by the rivet in contact with the flatwise extending panel 
portion when staked by the rivet to the panel portion; wherein the 
improvement comprises an annealed, tempered, tin-free steel can end; the 
pull tab stepped tip engaging the triple fold formation at an inner 
portion of the top layer of the triple fold where it curves downwardly to 
join the middle triple fold layer; the outer end of the stepped tip 
overlying the score line; and a moustache cut formed in the upper surface 
of the flatwise extending panel portion close to the rivet and 
encompassing the rear and sides of the rivet and terminating in wings 
lying laterally in front of the front portion of the rivet.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A generally typical steel can body 1 is illustrated in FIG. 1 with the 
improved steel can end generally indicated at 2 seamed to the upper end of 
the side wall of the can body. The steel can end 2 (FIGS. 7 and 15) may be 
made generally, but with modification, in the manner described in U.S. 
Pat. Nos. 3,871,314 and 4,116,361. Also the triple fold formation 3 
provided in the can end 2 may be modified from the constructions shown in 
U.S. Pat. Nos. 4,116,360 and 4,116,361. A pull tab generally indicated at 
4 may be riveted at 5 to the can end, the pull tab 4 having a construction 
modified from that shown in U.S. Pat. No. 4,042,144. The various 
modifications indicated are described in detail below. 
FIG. 12 illustrates in general the triple fold formation in the can end 
which extends 360.degree. around the can end, spaced inward from the can 
end corner 6. The end wall extends from corner 6 to a curved upward and 
outward portion 7, terminating in a curled periphery 8 which forms part of 
the usual double seam 9 when the can end 2 is seamed to the can body 1 
(FIG. 1). 
The score line 10, generally V-shaped in cross section with a slight flat 
at the bottom of the vee (FIGS. 12 and 13), which defines the opening to 
be formed in the can end 2, is located in the top layer 11 of the triple 
fold formation 3 above and spaced slightly radially inward of the rounded 
wall 12 connecting the middle and bottom layer portions of the triple fold 
3. The main panel portion 13 of the can end 2 lies in the plane of and 
extends inward from the bottom layer 14 of the triple fold 3. Preferably a 
central recess 15 is formed in the can end 2 for a purpose to be 
described. 
Initially, in attempting to manufacture a full opening can end from steel 
rather than from aluminum, the general procedure set forth in U.S. Pat. 
Nos. 3,871,314 and 4,116,361 was used but had to be modified. The contour 
of the panel portion shown in U.S. Pat. No. 4,116,361, including a flat 
panel portion 13 extending inward of and in the plane of the bottom layer 
14 of the triple fold formation 3 (except for the central recess 15) was 
used. The raised panel portion was omitted surrounded by a groove between 
the raised panel portion and the triple fold shown in the aluminum can end 
described in U.S. Pat. No. 4,116,360. 
This modified procedure is illustrated in FIGS. 2 through 7 wherein the 
various stage blanks as well as the starting blank 16 and the final can 
end 2 are illustrated. A usual cup-shaped and flanged starting blank 16 is 
drawn as illustrated in FIGS. 2 and 2A from light gauge steel. The next 
step is to draw a bubble formation 17 in the starting blank 16, to provide 
the stage blank 18. The next step is to complete the rivet formation 19 in 
stage blank 18 to form the stage blank 20. In this manner the bubble 
formation 17 and surrounding metal at the base of the rivet formation 19 
is reshaped. 
In the next stage operation the score line 10 and a moustache cut 21 are 
formed to produce the stage blank 22 (FIGS. 5 and 10). The next operation 
involves forming the triple fold 3 extending below the score line 10 (FIG. 
12) to produce the final stage blank 23 (FIG. 6). 
Finally, the completed steel can end 2 is formed by staking a pull tab 4 to 
the final stage blank 23 with the completed rivet 5 as shown in FIGS. 7 
and 15. 
As indicated, the procedure of U.S. Pat. Nos. 3,871,314 and 4,116,361 was 
modified in initial attempts to manufacture a steel can end 2 in 
accordance with the steps of FIGS. 2 through 7. This modification resulted 
because it was discovered in attempting to form the can end 2 from steel 
rather than from aluminum, that in the final forming of the rivet 
formation 19 under the prior art procedure to produce the stage blank 20, 
gathering or wrinkling of the metal at the base of the rivet formation 19 
occurred in an area surrounding the base of the rivet formation. This area 
where such gathering or wrinkling occurred in prior art procedure is 
diagrammatically indicated at A in FIGS. 4 and 9. Such gathered metal in 
area A in part prevented a satisfactory full overlap of the rivet head 
from being obtained when the pull tab 4 was staked to the can end 2 as in 
FIGS. 7 and 15. 
In order to eliminate the gathering of metal at A at the base of the rivet 
and to obtain an efficient and satisfactory full overlap when staking the 
rivet 5 to the pull tab 4, the entire shape and character of the bubble 
formed in stage blank 18 was changed to that shown in FIGS. 8 and 16. 
A greatly enlarged sectional view of the dies used to form the bubble 
formation 17 is shown in FIG. 16. The lower die 24 has a rounded central 
portion 25 merging into a conical surface 26 which is connected by a 
circumferential rounded fillet 27 to flat die surface 28. The upper die 29 
has a central opening 30 therein connected by a curved surface 31 with a 
conical surface 32 matching the conical surface 26 of the lower die. The 
conical surface 32 terminates in a curved wall 33 connected with the 
surrounding flat surface 34. 
The dies 24-29 are used to form the bubble portion 17 in the starting blank 
16 to form the stage blank 18 as shown in FIG. 8. Portions of the stage 
blank with the bubble 17 being formed therein also are shown in FIG. 16. 
The bubble formation 17 has a rounded central wall 35 at the top of a 
cylindrical neck 36 which is connected with the conical wall 37. Wall 37 
merges into the panel portion 13 of the stage blank 18 which is also the 
panel portion 13 of the steel can end 2 (FIG. 7), which is torn away along 
the score line 10 when the can end 2 is opened. 
In forming the bubble portion 17 in the dies 24-29, the metal in the 
conical wall 37 is substantially thinned, and cold-worked by the pressure 
between the conical surfaces 26 and 32 of the dies 24-29. This 
cold-working and thinning causes metal to flow upward within the central 
opening 30 in the upper die 29 to form the neck 36. The neck 36 terminates 
or is closed by a wall or cap 35 which is slightly bowed upwardly. 
This bowed or rounded cap 35 is not cold-worked to any material degree 
except as a result of the slight lateral squeezing pressure imparted to 
the metal in being forced into the die opening 30. Thus, the bowed cap 35 
of the bubble formation 17 remains relatively soft. The height of the 
bowed cap 35 when formed in the dies 24-29 (FIG. 16) should not extend 
beyond 0.123" from the bottom surface of the panel portion 13 the metal 
thickness of which is approximately 0.0083", the gauge of the steel from 
which the can ends are made. 
When the bubble formation 17 is redrawn and reshaped to the rivet formation 
19 (FIG. 9), the height of the cap 35 above the top surface of the panel 
portion 13 is substantially reduced with respect to its height above the 
panel portion 13 in FIG. 8. 
In reducing the height of the cap 35 to the location shown in FIG. 9 to 
produce the rivet formation 19 in stage blank 20 (FIG. 9), the conical 
wall 37 in stage blank 18 is redrawn and reshaped to form the cylindrical 
rivet neck 39 and the flat ringlike area 40 surrounding the base or lower 
end of the rivet formation 19. 
The metal in area 40 is coined and cold-worked and substantially flat and 
free of wrinkles. This is the area where wrinkles were formed, when using 
the prior art procedure, and where wrinkles were located in the discussion 
of the area designated A. The portions 39 and 40 of the stage blank 20 
thus are cold-worked and stiffened and somewhat thinner than the remaining 
metal in the panel portion 13 where the rivet formation 19 is located. 
The characteristics of the score line 10 in the steel can end 2 are very 
important (FIG. 13) since the metal thickness between the bottom of the 
vee and the under-surface of the top layer 11 of the triple fold formation 
3, the "residual", should be 0.0023" plus or minus 0.0003", indicated at 
R, where the gauge of the steel from which the can ends are made is 
nominally 0.0083", indicated at G. This relationship is critical or vital 
so that the residual is small enough to permit the panel portion 13 to be 
torn from the can when being opened by an aluminum pull tab 3 and yet the 
residual is sufficient to maintain integrity of the can end during 
shipment, handling, storage and use of steel cans 1 filled with food 
product and closed by the new steel can end 2. 
As indicated, the score line preferably extends 300.degree. around the can 
end so that when the can end is opened, as shown in FIG. 20, a 60.degree. 
segment of the panel portion 13 remains attached to the can to avoid 
littering with an open can and a separate torn-out portion. This is much 
to be desired in the use of and opening of cans, even though a 60.degree. 
segment of the panel portion 13 remains attached to the can when the 
torn-out panel portion is bent up as shown in FIG. 20 along a bend area 
38. Essentially the bend area 38 is a chord defining the 60.degree. 
segment described. However, the open area in the can end (FIG. 20) is 
substantially a full opening in the can to all intents and purposes. 
Obviously in those instances where retention of the torn-out portion on the 
can is neither desired nor required, the score line may extend 360.degree. 
around the can end to permit complete tear out of a panel portion 13. 
Other modifications of prior art constructions referred to were required in 
order to permit the use of an aluminum pull tab substantially the same as 
that shown in U.S. Pat. No. 4,042,144 and to prevent such pull tabs from 
being torn adjacent the rivet connection to the can ends when opening the 
new steel can end 2. 
These modifications involve slight changes in the shape and contour of the 
aluminum pull tab to be described, and the provision of a so-called 
moustache cut 21 in the rivet area A (FIGS. 5, 10 and 11). Moustache cuts 
have been known and are old in the beverage can field, where a teardrop 
opening is formed by complete or bending removal of can end portions from 
within the outline of the teardrop. The teardrop opening is formed by 
manipulating a pull tab riveted to the removed portion usually with a 
rivet located at the center of the can. These prior beverage cans usually 
have been formed of aluminum and the moustache cut is located behind the 
rivet so that the moustache cut is ruptured first during the initial 
opening movement of the pull tab to permit relief of pressure from within 
the can through the very small moustache cut opening from below the hand 
of the user and below the pull tab. 
However, in accordance with the present invention, the moustache cut is 
used for an entirely different purpose (not for pressure relief) but in a 
steel can end in which an aluminum pull tab is riveted to a steel triple 
fold protected can end close to the full opening score line provided in 
the steel can end. 
The function of the moustache cut is to enable the pull tab acting as a 
lever initially to rupture the panel portion immediately behind the rivet 
and close to the score line so that after the panel portion is ruptured 
the stiff and strong aluminum pull tab again acting as a lever ruptures 
the main score line with the tip of the pull tab as a second stage of can 
opening procedure. Then in a third stage of the procedure the pull tab is 
pulled upward to tear the panel portion along the score line. 
Such coordination between the moustache cut, rivet, rivet location and pull 
tab characteristics have been found to substantially avoid the likelihood 
of an aluminum pull tab being torn from the can end during the process of 
attempting to open a steel can end. 
It was discovered in developing the can end of the invention that the 
moustache cut 21 had to be located as close as possible to the rivet 
formation 19 with its curved central portion 41 encompassing the rear of 
the rivet formation 19 and extending in the panel portion 13 laterally 
outwardly at each side of the rivet formation 19 at 42, and terminating in 
curved wings or extremities 43 as indicated somewhat diagrammatically in 
FIG. 11. The laterally outwardly extending portions and curved wings 42-43 
as shown in FIG. 11 lie laterally in front of the front portion of the 
rivet formation 19. 
Although FIGS. 10 and 11 view the underside of the stage blank 22, and the 
moustache cut 21 is formed in the top surface of the panel portion 13 
(FIG. 5), the working of the metal in forming the moustache cut score line 
21 produces a shiny area of some width, having the moustache cut shape, on 
the underside of the panel portion 13 as indicated diagrammatically by 
stipling the substantial width of the outlined moustache cut shape 
appearing as a cold-worked metal on the underside of the panel portion 13, 
not only in FIG. 11 but also in FIG. 10. 
The curved central portion 41 of the moustache cut 21 should be located at 
approximately 0.094" away from the center of the rivet formation 19 in 
order to achieve its function. This locates the curved central portion 41 
immediately over the flat ringlike area 40 described above at A in 
connection with completing the rivet formation 19 as shown in FIG. 9. The 
ringlike area 40 formed in stage blank 20 (FIG. 4) thus becomes the area 
wherein portions of the moustache cut are formed in producing the stage 
blank 22 of FIG. 5. The location of the moustache cut in the cold-worked 
ringlike area 40 was not feasible until the problems relating to wrinkling 
in the area A were eliminated. 
Moustache cuts also are known in full opening aluminum can end construction 
as shown in U.S. Pat. No. 4,182,460 where a moustache cut is located on 
the inside panel surface at the rear of a rivet staking a pull tab to a 
removable panel defined by a score line extending 360.degree. around the 
can end. Here again the purpose or function of the moustache cut as stated 
in said U.S. Pat. No. 4,182,460 is for venting the interior of the 
container as in beverage cans. 
Further, this prior construction does not involve a removable panel portion 
having a triple fold protected edge. In addition, the pull tab has a blunt 
nose formed by a flange extending downward perpendicular to the panel 
portion around the periphery of the nose and engages the panel portion at 
a location spaced a considerable distance radially inward of the score 
line to be ruptured by the pull tab as shown in said U.S. Pat. No. 
4,182,460. 
The modifications involving changes in the shape and contour of the 
aluminum pull tab relate to modifying the construction shown in U.S. Pat. 
No. 4,042,144. In the prior construction the nose bottom wall has an ear 
formed therein with which the rivet is engaged surrounded at its sides by 
lanced cutout areas, which permit a hinge action to occur extending 
between the ends of the lanced portions in front of the rivet when the 
pull tab is used to open a can as illustrated in U.S. Pat. No. 4,042,144. 
This structure is modified in the aluminum pull tab forming part of the can 
end construction of the invention, by eliminating these prior art lanced 
portions so that the nose bottom wall 44 (FIGS. 1 and 7) is unlanced or 
not cut out at the sides of the rivet 5 around the opening 47 through 
which the rivet 5 extends. In this manner, the nose bottom wall 44 has a 
slightly curved rear edge 45 (FIG. 7) lying entirely behind and spaced 
from the opening 47 for rivet 5 so as to prevent any hinging of the pull 
tab on a bend line in the nose bottom wall 44 in front of the rivet. 
Another modification in the aluminum pull tab construction involving 
changes in the shape and construction which characterize the present 
invention relates to the nose or tip of the pull tab and to the stepped 
formation therein indicated at 46 and referred to as a "stepped tip". This 
stepped tip has a height of 0.005" from the bottom of the stepped tip 46 
to the under-surface 44a of the nose bottom wall 44 (FIG. 14) when the 
steel can end is made of nominal 0.0083" gauge steel. This stepped tip 
height is very substantially less than the height of the stepped tip in 
the prior patent in order to achieve the purposes of the invention. 
The stepped tip 46, the location of the rivet 5 with respect to the stepped 
tip 46 and the location of the panel portion 13 in the plane of the bottom 
layer 14 of the triple fold formation 3 (FIG. 15) preloads the pull tab 4 
when staked to the steel can end 2 as shown in FIGS. 1, 7 and 15. 
In this preloaded condition, the stepped tip 46 is engaged with the triple 
fold formation 3 at the inner portion of the top layer 11 of the triple 
fold where it curves downwardly to join the middle triple fold layer, and 
the outer end of the stepped tip overlies the score line groove 10, and 
the flat panel portion 13 is deflected upwardly a slight degree between 
the triple fold formation 3 and the rivet 5 as indicated in FIG. 15 by the 
space 50 between the nose bottom wall 44 of the pull tab 4 and the top 
surface of the panel portion 13. 
The described cooperative and interrelated relationship between the various 
parts of the can end 2, its triple fold formation 3, pull tab 4 and rivet 
5 establish conditions which permit the ready and easy opening of the can 
end 2 when formed of steel with an aluminum pull tab as described in 
connection with FIGS. 17 to 20. 
The upper end of a can 1 closed by the new steel can end construction 2 is 
illustrated in FIG. 17. When it is desired to open the can end, the rear 
end 49 of the pull tab 4 is engaged by a finger 51 of the user behind the 
heel 48 as shown in FIG. 18 and said rear end 49 is raised. As the rear 
end of the pull tab 4 is thus raised the moustache cut pops, indicated at 
52, as a first step in the opening sequence by the lever action of the 
pull tab 4 pulling the rivet 5 upward with the stepped tip of the pull tab 
4 engaged on the triple fold formation 3. 
As the pull tab continues to be raised to a vertical position such as shown 
in FIG. 19 during the second step in the opening sequence the metal panel 
portion pops at the front of the pull tab stepped tip as the stepped tip 
wipes inward across the score line 10 accompanied by bending of the panel 
portion 13 in the region of the wings 43 of the moustache cut 21 beyond 
the ends of said wings 43. During this stage in the opening procedure the 
metal in the panel portion 13 along the bent portions beyond the ends of 
the wings 43 continues to stay connected by the rivet 5 with and to extend 
adjacent to the nose bottom wall 44 as generally indicated at 53 in FIG. 
19. 
As the stepped tip 46 of the pull tab 4 wipes across the score line 10 a 
little nick or depression indicated at 54 in FIGS. 19 and 20 is formed in 
the portion of the can end remaining connected to the corner 6 adjacent 
the double seam 9. 
The pull tab 4 then is pulled upward and rearward generally in the 
direction of the arrow 55 in FIG. 20, to complete the final step of the 
opening sequence for the steel can end construction providing the can 1 
with the substantially full opening while retaining the torn panel portion 
13 and its pull tab 4 connected to the can 1. 
After overcoming all of the problems encountered in the construction and 
use of a steel can end opened with an aluminum pull tab to enable easy 
opening of the can end, it was determined that the construction would not 
satisfactorily comply with or pass government Drop Test requirements 
indicated by "leakers" which sometimes occurred when the filled cans 
closed by the new steel can end construction were subjected to Drop Tests. 
This problem was finally overcome by changing the type and physical 
properties of the steel used to form the new steel can end construction. 
The new construction was able to pass the required Drop Tests when the 
steel can ends are made of 75# (nominal 0.0083") Tin-free Steel, Single 
Reduced Mill Rolled, Temper 4, 7C Finish, Continuous Anneal, Continuous 
Cast Aluminum Deoxidized. It is believed that this particular type of 
steel sufficiently changes the physical characteristics of the metal in 
the areas adjacent the moustache cut and the main score line, where the 
metal has been cold-worked in the manufacture of the can ends, so that the 
residuals of the score line and moustache cut having the dimensions 
necessary to permit easy opening, resist splitting or fracturing by the 
shock forces to which the cans and can ends are subjected when the Drop 
Tests are made. 
Accordingly, the improved steel can end construction having the cooperative 
and interrelated relationships between the various parts and components of 
the steel can end and its protective triple fold and its aluminum tab 
described, results in a steel food can product capable of being very 
easily opened with a substantially full opening and with the torn-out 
portions of the can end remaining connected to the can, which satisfies a 
need in the canned food products field that has long existed, thereby 
achieving the indicated objectives simply and efficiently and with lower 
cost than food cans having prior triple fold protected aluminum can ends, 
and solving existing problems in the canned food products field. 
In the foregoing description, certain terms have been used for brevity, 
clearness, and understanding; but no unnecessary limitations are to be 
implied therefrom beyond the requirements of the prior art because such 
terms are used for descriptive purposes and are intended to be broadly 
construed. 
Moreover, the description and illustration of the invention is by way of 
example, and the scope of the invention is not limited to the exact 
details shown or described, since the features of the invention may be 
applied to different sizes and types of cans and steel can ends. 
Having now described the features, discoveries and principles of the 
invention, the manner in which the improved structures achieve the 
objectives, and the advantageous, new and useful results obtained; the new 
and useful structures, devices, elements, arrangements, parts, components, 
cooperative arrangements of components, and combinations are set forth in 
the appended claims.