U.S. patent number 3,881,630 [Application Number 05/463,056] was granted by the patent office on 1975-05-06 for pop-in container closure.
Invention is credited to Frederick G. J. Grise, Walter C. Lovell.
United States Patent |
3,881,630 |
Lovell , et al. |
May 6, 1975 |
Pop-in container closure
Abstract
A container lid, by the steps of shear-coining over die surfaces
to provide a fracture, and a swedging, comprises a peripherally
dilated button portion which adequately resists internal fluid
pressures, yet is disruptable by external finger pressure urging
the button portion inwardly. The fracture terminates within a wall
of the button portion, being sealed by surfaces preferably swedged
into overlapping relation. The button may be provided with a
non-disruptable or hinge portion, or formed to enable it to fall
into the container, the button in either case not being separately
disposable. No harmful closure edges are exposed.
Inventors: |
Lovell; Walter C. (Wilbraham,
MA), Grise; Frederick G. J. (Wilbraham, MA) |
Family
ID: |
26987954 |
Appl.
No.: |
05/463,056 |
Filed: |
April 22, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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331844 |
Feb 12, 1973 |
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Current U.S.
Class: |
220/268 |
Current CPC
Class: |
B21D
51/383 (20130101); B65D 17/401 (20180101); B65D
17/404 (20180101) |
Current International
Class: |
B21D
51/38 (20060101); B65d 041/32 () |
Field of
Search: |
;220/266,267,268,276
;222/541 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hall; George T.
Attorney, Agent or Firm: Johnson; Carl E. White; Vincent A.
Megley; Richard B.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application Ser. No.
331,844, now abandoned, filed Feb. 12, 1973, in the names of Walter
Lovell and Frederick G. J. Grise, and relating to "Environmental
Pop-In Button Closure for a Can". Application Ser. No. 454,384
pertaining to the method aspects of this invention is also a
continuation-in-part of application Ser. No. 331,844.
Claims
Having thus described my invention, what I claim as new and desire
to be secured by Letters Patent of the United States is:
1. A manually disruptable pop-in type of button closure for a
planar metal container lid comprising an integral button having
inner and outer merging bounding walls generally inclined to the
plane of the lid, one of the walls having opposite sides and being
longitudinally indented on one side to provide a fracture extending
between the bottom of the indentation and the other side of the one
wall, and a face of the indentation being dilated relative to the
fracture to permit its disruption from outside the container yet
effectively resist internal pressure therein.
2. The closure of claim 1 wherein it is the outer bounding wall
which is longitudinally indented, and has a transverse convexity
along a portion of its length, the depth of the indention tapering
to provide a locality for facilitating the start of the
disruption.
3. The closure of claim 1 wherein the indentation depth tapers in
diminishing degree peripherally to a locality of substantially no
fracture and the indentation is discontinued at a locality whereat
the button has a hinging connection to the lid.
4. A button closure manually disruptable in an integral lid for
access to the contents of a container, the closure being defined at
least in part by a bounding wall extending transversely out of the
plane of the lid, the wall having an indentation extending
lengthwise provided by angularly related faces and a through
fracture terminating substantially at the junction of the faces,
one of said faces being dilated outwardly of said junction whereby
the opposite mating portions of the fracture are releasably locked
in close association.
5. A button closure as in claim 4 and a coating of lacquer on at
least the indentation faces to seal said junction.
6. A sheet metal container lid comprising an integral, disruptable
pop-in type of button closure, the closure having an outer,
sectionally convex boundary wall, a coined longitudinal indentation
formed in one of the two opposite sides of the wall and having a
bottom face of generally uniform width on the order of about
one-fifth to one-third the thickness of the lid, and a fracture
extending from the said bottom face substantially to the other of
said two wall sides.
7. A lid as in claim 6 wherein swedged metal from a peripheral wall
of the indentation overlaps the fracture at said bottom face for
sealing it.
8. A sheet metal container lid comprising an integral, disruptable
pop-in type of button closure, the closure being largely defined by
a continuous depression in the lid, and a bounding wall which, in
section, is generally angularly related to the lid, a longitudinal
indentation in the bounding wall, a fracture terminating interiorly
of the wall substantially at the bottom of said indentation, and at
least a portion of the metal adjacent to a peripheral face of the
indentation being dilated to partly overlap the bottom surface of
the indentation substantially at the interior terminal portion of
said fracture.
9. A lid as in claim 8 wherein, without removal of material, a
second longitudinal indentation is formed in said metal adjacent to
a peripheral face of the aforementioned indentation to hold
confronting mating portions of the fracture in close
association.
10. A sheet metal container lid comprising an integral, disruptable
pop-in type closure, said closure being largely defined by a
continuous depression in the lid providing a bounding wall having
an upstanding ridge portion, the wall having a longitudinal
indentation outwardly of the ridge portion and a fracture
terminating in the wall interiorly at the bottom of said
indentation, mating metal portions on opposite sides of the
fracture being in tension and dilated into closed relation by a
swedging of said ridge portion, and the metal immediately adjacent
to one face of said indentation being extruded into partly
overlapping relation to the bottom of said indentation to lock and
seal the mating portions of said fracture.
11. In a sheet metal container lid, an integral disruptable pop-in
type closure, said closure being defined by a bounding wall
projecting out of the plane of the lid, the wall having a pair of
adjacent peripheral indentations and a fracture terminating
interiorly of the wall at the bottom of one of said indentations, a
face of the other indentation being dilated to extrude metal which
partly overlaps and seals the interior terminus of the
fracture.
12. A lid as in claim 11 wherein the wall is transversely convex
and includes a ridge portion, and said fracture extends from the
bottom of that one of said pair of peripheral indentations more
outwardly from said ridge portion.
13. A lid as in claim 11 wherein the depth of said one of the
peripheral indentations tapers from a maximum toward a peripheral
locality wherein there is no fracture thereby providing a hinging
connection for the closure.
14. A lid as in claim 11 wherein the peripheral indentations extend
in substantially parallel relation, are respectively generally
angular in transverse section to provide an intermediate strip, and
said strip is swedged to extrude metal for sealing the fracture by
partly overlapping the bottom of the adjacent indentation.
15. In a sheet metal container lid, an integral, disruptable button
closure, the closure having a peripheral ridge formed by a pair of
merging walls inclined to and coincident with the lid, a
longitudinal indentation extending in one of said walls and having
a generally W-shaped or double indent configuration in
cross-section, the bottom of the indentation nearly connecting with
a fracture extending through said one wall, and a portion of the
median strip of the W-shaped indentation being swedged to extrude
the metal of one face of the strip into sealing relation with said
fracture.
16. A lid as in claim 15 wherein the fracture diminishes as it
peripherally approaches a non-indented portion of the periphery of
the button closure and is discontinued at said portion of the
periphery.
Description
BACKGROUND OF THE INVENTION
This invention pertains to a tabless, push-in type closure for the
sheet metal lid of a container adapted to retain fluid under
pressure.
In the prior art, several different closures of the so-called
"pop-in" type have been proposed. Some required a leverage tab or
lifting projection and scoring in the lid, and others such as
disclosed, for instance, in U.S. Pat. Nos. 3,227,304 to Asbury, or
3,334,775 to Klein et al., specify a score line in a flat region,
or a score line in a wide angle notch, but in a fold such as to
preclude reliable operation or uniformity in manufacture. When the
latter types can be "pushed-in" they commonly have inadequate
strength to resist internal pressure such as may be present in a
carbonated beverage or a pasteurized fluid.
An easy-open lid construction providing no separately disposable
parts is generally recognized as very desirable provided it can
safely retain fluid pressures and yet be uniformly reproduced by a
practical method.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of this invention to
provide a simple, economical, reliable push-in closure useful in
sheet metal container lids.
More specifically, another object of this invention is to provide
improved container structure reinforcing the margins of push-in
button portions of can lids whereby fluids can be safely contained
yet manual access be readily available by rupture of the
margins.
To these ends, and as herein illustrated, a metal lid is first
formed with a recess providing a button having inner and outer
bounding walls merging in a peripheral ridge on one side of the
lid. Next a coin-shearing operation is performed, preferably in a
convex portion of the outer button wall, to provide (as per one
mode of the invention) a peripheral indentation having convergent
angular faces meeting at a fracture extending through the metal of
the wall. Then, while the thus indented wall is backed by a die
having complemental (preferably convex) curvature, a swedging
operation against the peripheral ridge dilates the metal of the
outer wall to force one of the indentation faces into partly
overlapping relation to the other face, by a few thousandths of an
inch over its length, and enables the metal in the locality of
fracture to spring substantially closed. A lacquer coating may
thereafter be applied for sealing, if desired, to the button
internal surface, but is often unnecessary.
While the "single indent" form of the lid button closure just
described is generally satisfactory, this invention also
comprehends a closure of similar construction but which may be
referred to, for reasons hereinafter becoming apparent, as the
"double indent" type. The latter involves a modified swedging for
providing a mechanical locking of the metal at the fracture, a
localized peripheral portion of the wall metal being forced to flow
into the shear-coined indentation to prevent fluid penetration of
the fracture and overlap the bottom face of the indentation. This
advantageously dilated button construction, as herein disclosed,
need not involve extra tooling or operating time.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other features of the invention will now be more
particularly described in connection with an illustrative
embodiment and a variant form and with reference to the
accompanying drawings thereof, in which:
FIG. 1 is a perspective view of one illustrative embodiment of the
invention, a can top having a circular closed closure button hinged
to the lid;
FIG. 2 is a view similar to FIG. 1 and showing the button pushed
inwardly;
FIG. 3 is an enlarged diametral section showing a padded
coin-shearing die and a back-up die about to commence operation on
a lid, the button portion of which has previously been struck up
from the inside, or the surrounding material has been depressed
relative to the lid by a drawing die;
FIG. 4 is a section similar to FIG. 3 showing the button and parts
at bottom of peripheral fracture opening stage;
FIG. 5 is a section similar to FIG. 4 showing the parts at a
subsequent released or partial fracture reclosing stage;
FIG. 6 is a section similar to FIGS. 3-5 but indicating the final
stage wherein a swedging die, of flat as opposed to axially stepped
form shown in FIG. 9, dilates a wall of the shear-coined
indentation and tensions the fracture web over a convex back-up
surface;
FIG. 7 is a further enlarged detail view, predicated on a typical
photomicrograph showing in transverse section the released button
wall having a sprung together fracture and a dilated indentation
face at least partly overhanging the wall fracture, and lacquer
coating applied thereto;
FIG. 8 is a perspective view corresponding in part to a portion of
FIG. 2 and showing the closure of FIGS. 1-7 inclusive being opened;
and
FIG. 9 is a view similar to FIG. 7, but omitting the lacquer and
showing an important variant, a double-indent button closure wall
as magnified to reveal the fracture reclosed upon retraction of an
axially stepped swedge.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the following disclosure it will be appreciated that certain
critical physical distinctions resulting from method and structure
obtaining in this case over prior art may be dimensionally small
and possibly to the point of being invisible to the naked eye. It
will nevertheless be understood, as hereinafter pointed out, that
despite possibly small dimensional changes involved, the
significance of the novel structure to be described is real and of
considerable importance from both the standpoint of manufacturing
advantage and improved closure performance.
FIGS. 1-8 inclusive pertain to a so-called single indent closure,
and an important variant is subsequently described with reference
to FIG. 9.
FIG. 1 shows a conventional can 10 having a rim 12, usually the
chime of an otherwise planar sheet metal lid 14 (FIGS. 1-8). A
pop-in closure 16 for instance of circular shape like a button, to
be manually pressed inwardly for opening the container lid is
preferably positioned adjacent to the chime. It will be understood
that neither the lid or its button portion 16 need be circular. The
lid 14 is first formed as by a die (not shown) to provide its
button portion 16 with a surrounding continuous depression 18
bounded by inner and outer walls 20,22 respectively. Preferably the
flat of the integral button portion 16 remains only slightly
depressed with respect to the general plane of the lid 14 so as to
readily indicate the locality to be opened inwardly.
It will be noted (FIGS. 3-5) that the button walls 20,22 to be
processed as by steps hereinafter explained are desirably partly
convex in section and merge in a rounded trough 24. Walls 20,22
simply inclined to the plane of the lid without being convex may in
some cases be satisfactorily employed but are not usually
preferred. Regardless of the care with which the sheet metal is
originally made, there is no real control over its grain structure.
Accordingly, scoring a closure as thin as that found, for instance,
in beer cans requires an extra degree of penetration and sizing
control nicely afforded by the mentioned wall convexity in order to
prevent leakage on the one hand and yet, on the other hand, insure
manual accessibility to the container contents without requiring
extra finger strength. While it has been found that the invention
may be practiced on the inner wall 20, and whether it be
transversely arcuate or straight and inclined to the lid, it is
generally preferable to operate on the convex portion of the outer
wall 22, and usually at least about a third of its length, as will
hereinafter be explained.
Assuming the lid button 16 to be substantially in the configuration
shown in FIG. 3, the outer wall 22 is next shear-coined lengthwise
in its convex periphery. For this purpose an upper back-up die 26
(FIGS. 3-6) has an annularly projecting rounded ridge 28 formed to
fit in and engage the trough 24. A lower shear-coining die 29
(FIGS. 3-5) is arranged to cooperate coaxially with the back-up die
26, and has a vertically disposed cutting edge 30, an angularly
related narrow coining face 32, and a longer inclined coining face
34 extending outwardly from the face 32. The coining face 32
commonly will have a uniform width on the order of from about
one-fifth to one-third of the thickness of the lid, depending on
the particular sheet metal and the extent of fracture desired. In
this connection it may be noted that actual through-wall fracture
as a result of the shear-coining step is generally desired.
To clampingly hold the button 16 against bodily shifting laterally
on the die ridge 28 when the convex portion of the outer wall 22 is
peripherally shear-coined as shown in FIG. 4 during relative
approach of the dies 26,29, the latter die preferably has a
yieldingly compressible rubber pad 36 of uniform thickness nested
within the cutting edge 30.
As shown in FIG. 3, the coining face 32 axially tapers from a
maximum projection above the pad 36 on the right side of the die
periphery to a minimum on the left side substantially flush with
the pad 36. In this manner the periphery of the outer wall 32 is
variably shear-coined, providing a controlled indentation extending
substantially all around the button 16 but of tapering lesser depth
in the left-hand portion than in the right-hand portion as shown in
FIG. 4. The depth of the shear-coining is usually selected to
insure that the coining indentation concomittantly causes a
fracture 38 (FIGS. 4-7) all the way through the metal and extending
for roughly from about 120.degree. to 180.degree. around its
periphery. This fracture serves as an easily started locality of
rupture in the complete button. The locality of no indentation,
generally opposite to the locality of greatest indentation and/or
fracture, will serve as a hinge H (FIGS. 2 and 8) when the button
is pushed into the can 10.
It is to be noted that shear-coining the button wall 22 over a
transversely convex back-up die surface, i.e. outwardly of the
center of the annular die ridge 28, provides both a refined control
of the desired indentation and degree of the resultant fracture 38,
and an improved service life for the shear-coining die 29. The
latter is probably largely due to the freedom of the metal in the
wall 22 to flow as necessary during tensioning outwardly over the
curved surface of the die 26. It will be understood, nevertheless,
that this invention whether in the single or double indent form may
be utilized in either of the walls 20 or 22 and whether they be
convex, concave or straight but inclined to the lid.
When the dies 26,29 are relatively separated heightwise as shown in
FIG. 5 after shear-coining, resilience of the pad 36, which had
been distorted as indicated in FIG. 4, frees the lid for the last
step about to be described. No wall material has been removed. It
will be understood that the nearly 90.degree. angle at the bottom
of the peripheral indentation or groove initially imparted by the
convergent cutting edge 30 and the adjacent coining face 32 as
shown in FIG. 4 is partly reduced as indicated in FIG. 5 when
relative die retraction permits residual tension in the wall
material to be dispelled. Accordingly, mating irregular metal at
the fracture 38 springs substantially closed without appreciable
misalignment of confronting edges. No complete separation is
permanently incurred at the bottom of the wall indentation.
The final and perhaps most important step in this single-indent
button forming will next be described with reference to FIGS. 6
& 7. With the backing die 26 still in its work-engaging
position, swedging die 40 (FIG. 6) having a flat face 42
compressively bears on the walls 20,22 at the annular locality of
their convergence. This imposes a flat 44 on the periphery of the
button 16 opposite to the depression 18 and causes metal of the
indented wall 22 to flow outwardly. More significantly, and as
better shown in FIG. 7, as a consequence of the swedging an
indentation face 46 of the wall 22 is dilated and hence at least
partly overlaps a convergent indentation face 48 imparted by the
coin-face 32. This overlap which may be on the order of about two
to four thousandths of an inch on opposite sides of the button
respectively, is disposed outwardly of the fracture 38. The
swedging therefore stiffens the button wall in the vicinity of the
fracture, and generally appears to close the fracture; along its
length. A lacquer coating 50 (FIG. 7) may be applied at least to
seal the fracture and the indentation on the inside of the
completed lid.
A variant and important form of our novel closure, sometimes termed
the W configuration or double-indent form, is illustrated in FIG. 9
along with a portion of an axially stepped swedge 52 used in its
manufacture. As shown, the double indent form of peripheral wall
may be considered one having a W-shaped indentation in section.
Instead of having a single flat working surface 42 as is the case
with the swedge 40 of FIG. 6, the reciprocable swedge 52 has
axially stepped inner and outer working faces 54,56 and an
interconnecting wall disposed substantially at right angles
thereto. The diameter (or transverse dimension) of the swedge face
54 is less than the dimension between opposite coin-induced
fracture portions 38 and hence less than the dimension between
opposite coining faces 32. Axial offset of the faces 54,56
desirably is selected to enable the face 54 to engage the
die-backed ridge material and form a flat 60 (FIG. 9) forcing a
portion of the metal to flow outwardly into fracture closing
relation, and to enable the face 56 to apply a localized peripheral
axial indenting pressure on the thus outwardly displaced metal of
the bounding wall as at 58 (i.e. on the median strip of the
W-shape) whereby the confronting closely associated and mating
portions of the fracture, while held under tension by the face 54,
are tightly locked together. Whether such sequential swedging
occurs or not, almost simultaneously with this very effective
closing of the fracture 38 the narrower swedge face 56 bearing on
the double-indent face 58 of the median strip also causes a portion
of the strip metal (within the single thickness of the button wall)
to be extruded annularly and dilated outwardly into overlapping
relation with the bottom of the first indentation caused earlier by
the coining illustrated in FIG. 4.
It is to be noted in FIG. 9 that the fracture 38 now terminates
inwardly of the button surface and at the junction of the
overlapped or dilated metal with the coined indentation bottom.
Thus a better, i.e. a tighter sealing of the fracture 38 is
attained at the same time that an increased ability to retain fluid
under pressure is accomplished. Moreover, it will be observed that
no additional tooling or extra time consuming function is involved
in producing the double indent closure over the single indent type.
Accordingly, closures for holding greater pressure are presently
expected to be of the double indent form. The working width of the
swedge face 56 may be on the order of about one-half of the lid
thickness. Whether the single or double indent button closure is
used, it will be understood that an internal lacquer coating is
desirably added.
In contrast to prior art closures wherein the metal sheet is often
folded back upon itself, and control of the degree of fracture is
lost, the double indent type closure insures uniform, reliable
pressure holding capability, yet yields an easily cleanable
cover--one which readily sheds dirt or foreign matter during
washing.
Referring now more particularly to FIGS. 2 & 8, when the hinge
H of the button 16 is adjacent to the can chime, suitable indicia,
for instance an arrow (not shown), may indicate the diametrically
opposite locality of deepest shear-coining and fracture where
external finger pressure on the button can most easily start
rupture. Once rupture has been started along the fracture,
continued tearing of the metal along the remainder of the wall
indentation requires less pressure. It will be understood that if
internal hinging of the button H is not desired, a complete
360.degree. shear-coining and fracture as herein explained will
enable the closure to be separated inwardly and thereby deposited
within the can so as not to be separately disposable.
From the foregoing it will be clear that the swedging provides a
circumferential "growth" or dilation of the button 16, expanding
its initial transverse dimension or diameter D (perhaps on the
order of about six to eight thousandths of an inch total) outwardly
of the fracture 38 to overlap a part of the adjacent indentation
wall as indicated in FIG. 7 or FIG. 9. Accordingly internal fluid
pressure in the can tends only to close the wall indentation and
the fracture 38 but has no significant disrupting effect
thereon.
The described closures are applicable to various shapes of buttons
and containers, and are economically employed with a high degree of
precision control and hence uniformly reliable results.
* * * * *