U.S. patent number 3,837,524 [Application Number 05/336,404] was granted by the patent office on 1974-09-24 for easy opening container wall.
Invention is credited to Omar L. Brown, James R. Schubert.
United States Patent |
3,837,524 |
Schubert , et al. |
September 24, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
EASY OPENING CONTAINER WALL
Abstract
An easy opening container wall comprising a container wall of
sheet material having a line of weakness therein defining a tear
portion at least partially removable from the container wall.
Removal of the tear portion provides a relatively sharp edge along
the tear portion. A guard is provided along the periphery of the
tear portion to protect the consumer from injury. The guard is
interrupted adjacent the location at which the line of score is
initially ruptured to facilitate such initial rupture. The outer
periphery of the guard and the score line are configured and
positioned relative to each other to minimize interference by the
guard during the opening operation.
Inventors: |
Schubert; James R. (Dayton,
OH), Brown; Omar L. (Dayton, OH) |
Family
ID: |
26931415 |
Appl.
No.: |
05/336,404 |
Filed: |
February 28, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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238187 |
Mar 27, 1972 |
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Current U.S.
Class: |
220/269; 220/270;
220/906; 220/276; 220/712 |
Current CPC
Class: |
B21D
51/383 (20130101); Y10S 220/906 (20130101) |
Current International
Class: |
B21D
51/38 (20060101); B65d 017/20 () |
Field of
Search: |
;220/54,27,90.6,48 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hall; George T.
Attorney, Agent or Firm: Smyth, Roston & Pavitt
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application Ser. No.
238,187 filed Mar. 27, 1972, for COMBINED CAN AND END WITH MEANS
FOR PROTECTING AGAINST SEVERED SCORE.
Claims
We claim:
1. An easy opening container wall comprising:
a container wall of sheet material;
a line of weakness in the container wall defining a tear portion at
least partially removable therefrom;
first means attached to said tear portion for initiating rupture of
the sheet material by an inwardly directed force and for tearing
the sheet material generally along the line of weakness to at least
partially remove the tear portion from the container wall, said
tearing of sheet material providing a relatively sharp edge on the
tear portion, the initiation of rupture of the sheet material
occurring at a preselected region along the line of weakness;
second means on the tear portion and extending along a peripheral
region thereof for protecting the user against injury from the
sharp edge when the tear portion is at least partially removed from
the container wall; and
said second means being interrupted adjacent said preselected
region of the line of weakness sufficiently to substantially
prevent said second means from hindering the initiation of rupture
of the sheet material in response to said inwardly directed
force.
2. An easy opening container wall as defined in claim 1 wherein
said first means includes a tab at least a portion of which is
pivotable to rupture the sheet material at said preselected region
and along a segment of the line of weakness, said second means
lying radially inwardly of said line of weakness at the ends of
said segment.
3. An easy opening container wall comprising:
a container wall of sheet material;
a line of weakness in the container wall defining a rupturable web;
said rupturable web defining a tear portion at least partially
removable therefrom;
means attached to said tear portion for initiating rupture of the
rupturable web at a preselected region thereof by an inwardly
directed force and for tearing the rupturable web to at least
partially remove the tear portion from the container wall, said
tearing of the sheet material providing a relatively sharp edge on
the tear portion;
a guard on the inner side of said tear portion extending along the
periphery of the tear portion to protect the user against injury
from the sharp edge; and
said guard being spaced inwardly in a generally axial direction
from the rupturable web at least adjacent a portion of said
preselected region to facilitate the initiation of rupture of the
rupturable web at said preselected region by said inwardly directed
force.
4. An easy opening container wall as defined in claim 3 wherein
said guard includes multiple layers of sheet material of the tear
portion.
5. An easy opening container wall as defined in claim 3 wherein
said guard includes a guard bead.
6. An easy opening container wall comprising:
a container wall of sheet material;
a line of weakness in the container wall defining a tear portion at
least partially removable therefrom;
means attached to said tear portion for tearing the sheet material
generally along said line of weakness to at least partially remove
the tear portion from the container wall, said means initiating
rupture of the line of weakness by forcing a peripheral segment of
the tear portion inwardly;
said tear portion including a panel portion having and a marginal
region substantially circumscribing said panel section; reverse
bend section joined to said panel section and opening generally
radially inwardly,
the marginal region of said tear portionhaving a cross sectional
configuration which includes a first reverse bend section opening
generally radially outwardly, a second generally radially inwardly,
and a leg section joining said bend sections;
said second reverse bend section being in a radial position closely
adjacent the line of weakness to shield the user against injury
from the sharp edge; an
said second reverse bend section and at least a portion of said leg
section being spaced generally axially inwardly from at least a
portion of said peripheral segment to allow said peripheral segment
to be forced inwardly to initiate rupture of the line of weakness
without substantial interference form the bend sections and said
leg section.
7. An easy opening container wall as defined in claim 6 wherein
said tearing of the sheet material provides a relatively sharp edge
on the tear portion, said bend sections and said leg section at
least partially define a protector for protecting the user against
said sharp edge, and said initiation of rupture deforms said
peripheral segment inwardly into substantial contact with said leg
section whereby the protector can more efficiently protect the user
against injury from the portion of said sharp edge of the
peripheral segment.
8. An easy opening container wall comprising:
a container wall of sheet material having an inner side;
a line of weakness in the container wall defining a tear portion at
least partially removable therefrom;
first means attached to said tear portion for tearing the sheet
material generally along said line of weakness to at least
partially remove the tear portion from the container wall, said
tearing of the sheet material providing a relatively sharp edge on
the tear portion;
said first means including means for forcing a paddle section of
the tear portion inwardly to rupture the sheet material along a
segment of the line of weakness;
second means on said tear portion for protecting the user against
injury from the sharp edge;
said second means including an outer peripheral edge on the inner
side of said container wall extending generally along the line of
weakness; and
said edge lying radially inwardly of the line of weakness adjacent
the ends of said segment and radially outwardly of the line of
weakness along a major portion of the line of weakness.
9. An easy opening container wall as defined in claim 8 wherein
said edge is circular in plan and said line of weakness is
noncircular.
10. An easy opening container wall as defined in claim 9 wherein
said major portion of the line of weakness forms a part of a circle
which is substantially concentric with the circular edge.
11. An easy opening container wall as defined in claim 10 wherein
the portion of said edge which lies radially inwardly of the line
of weakness includes first and second arcs, each of said arcs
forming a portion of a circle and being nonconcentric with each
other and with said major portion of the line of weakness.
12. An easy opening container wall as defined in claim 8 wherein
said second means is interrupted along at least a portion of said
segment.
13. An easy opening container wall as defined in claim 8 wherein
said second means includes a guard bead, said edge being on said
guard bead.
14. An easy opening container wall as defined in claim 13 wherein
said guard bead has a cross sectional configuration which includes
a first reverse bend section opening generally radially outwardly,
a second reverse bend section joined to said panel section and
opening generally radially inwardly, and a leg section joining said
bend sections, said edge being a peripheral surface of the second
reverse bend section.
15. An easy opening container wall comprising:
a container wall of sheet material;
means forming a line of weakness in the container wall defining a
tear portion that is completely removable from said container
wall;
means attached to said tear portion for rupturing the sheet
material by forcing a paddle section of the tear portion inwardly
to rupture the sheet material along a segment of the line of
weakness;
means integral with said tear portion for protecting the user
against injury from the sharp edge formed after severance
thereof;
said integral means being of generally circular shape in plan view,
and
said line of weakness being concentric with respect to a portion of
said integral means and including a portion in the region of said
paddle which is not concentric with said integral means.
16. An easy opening container wall as set forth in claim 15 wherein
integral means includes a rounded edge defining, in the region of
concentricity with said line of weakness, a diameter in plan view
somewhat greater than that of the circle formed by said line of
weakness.
17. An easy opening container wall as set forth in claim 16 wherein
said rounded edge s located vertically below the plane of the line
of weakness whereby upon removal of the tear portion the rounded
edge extends beyond the sharp edge in the portion thereof
concentric with the sharp edge.
Description
BACKGROUND OF THE INVENTION
As is well known, when an easy opening container is opened, a tear
portion or panel is torn from the container to form an opening. The
tearing of the sheet material leaves a relatively sharp edge on the
removed panel and also leaves a relatively sharp edge on the rim of
the opening. These sharp edges are potential sources of danger to
the consumer particularly if the container or removed panel is
carelessly handled.
This problem is particularly acute in the so-called full panel
pullout in which the removed panel covers a major area of the can
end. These full panel pullout ends are often used on a food product
such as pudding, some of which may adhere to the inner or
non-public side of the panel. When this occurs, the consumer may
lick the inner surface of the removed panel and by so doing may cut
his tongue. This of course is only one example of how one of the
sharp edges on the panel can produce injury.
In our earlier copending application, this problem is solved by a
protector or guard on the tear portion which extends along the
periphery of the tear portion. The guard provides a relatively dull
surface adjacent the sharp edge which shields the user from the
sharp edge.
In one form, the guard includes multiple layers of sheet material
formed integrally with the tear portion. Although the guard very
adequately solves the injury problem, it introduces two additional
problems. First, the guard inhibits the initiation of severance of
the sheet material along the line of weakness. Specifically, easy
opening container walls of this type are typically opened by
depressing a peripheral segment of the tear portion inwardly. The
guard, which may be in the form of a relatively stiff guard bead on
the inner side of the tear portion, resists inward movement of the
peripheral segment. Therefore, the initial "pop" is more difficult
to obtain.
Following the initial pop, a paddle section of the tear portion is
bent inwardly, usually about a bend zone, to rupture a segment of
the sheet material along the line of weakness. This inward bending
of the paddle section is typically brought about by pivotal
movement of the opening tab.
Following such pivotal movement of the tab, the user pulls
outwardly on the tab to pull out the panel from the container wall.
The guard, however, has an edge which lies radially outwardly of
the line of weakness. This edge tends to hang up during the initial
pull on the tab so that the initial portion of the pulling phase of
the opening operation is made more difficult.
SUMMARY OF THE INVENTION
The present invention facilitates the initial severance or pop of
the sheet material at the line of weakness by interrupting the
guard at the peripheral segment of tear portion which is depressed
inwardly. Interruption of the guard could be a simple absence of
the guard at the peripheral segment. However, this would mean a
loss of protection at the peripheral segment. Accordingly, a better
form of interruption is an appropriate discontinuity of the guard
without completely eliminating it.
In one preferred form of the invention, the guard includes a guard
bead located axially inwardly of the line of weakness. With this
construction, the guard is interrupted at the peripheral segment by
spacing the guard bead axially inwardly from the peripheral segment
to thereby allow the peripheral segment to be forced inwardly to
initiate rupture of the sheet material without substantial
interference from the guard bead. Another advantage of this
construction is that when the peripheral segment is forced
inwardly, it is deformed into substantial contact with the guard
bead. Accordingly, the guard bead, once the tear portion is
removed, is fully effective, even at the peripheral segment, to
protect the user against injury.
The present invention also facilitates the initial pull phase of
the tear portion removal operation. The guard has an edge on the
inner or nonpublic side of the container wall which extends
generally along the line of weakness. The edge of the guard lies
radially outwardly of the line of weakness along a major portion of
the line of weakness to thereby provide maximum protection against
injury from the sharp edge. However, the edge lies slightly
radially inwardly adjacent the portions of the line of weakness
which are ruptured by the initial pull on the tab. As the edge lies
radially inwardly of these portions of the line of weakness, it
cannot increase the resistance to the initial pull of the tab.
Although the edge may lie slightly radially outwardly of a major
portion of the line of weakness, it has been found that this does
not create any significant resistance to the pulling phase of the
removal operation after the initial pull is accomplished
The present invention also provides a novel and advantageous method
of making a double fold in sheet material. This method can be used
to particular advantage in constructing a preferred form of the
easy opening container wall of this invention.
According to the method of this invention, a piece of sheet
material is provided with the sheet material having first and
second axially offset radial sections integrally joined by a
generally axial wall. The second radial section has an expansion
rib formed integrally therewith adjacent the axial wall.
Next axially directed compressive forces are applied to the
expansion rib to completely flatten the rib. Flattening of the rib
results in the application of a radial outward force to the
adjacent end of the axial wall. The effect of collapsing the
expansion rib is to incline the axial wall in a known direction so
that when axial compressive forces are applied to the two radial
sections a double fold will be provided. As this double fold or
pair of reverse bends is of the type which can be used to form a
guard for the easy opening container wall of this invention, this
method is particularly adapted for use in making the preferred form
of the easy opening container wall.
Another feature of the method of this invention is the manner in
which the guard bead is caused to be spaced from the peripheral
segment of the tear portion which is first ruptured by the tab.
This can be advantageously accomplished by providing a space into
which the guard can move during the work operation which results in
the formation of the guard.
The invention can best be understood by reference to the following
description taken in connection with the accompanying illustrative
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of an easy opening container having a
protector to protect the user against injury from the sharp edge of
the tear portion.
FIG. 2 is an enlarged fragmentary sectional view taken generally
along line 2--2 of FIG. 1.
FIG. 3 is a fragmentary sectional view of the container with the
panel removed.
FIGS. 4 and 5 are enlarged fragmentary sectional views taken
generally along lines 4--4 and 5--5, respectively, of FIG. 1.
FIG. 6 is a schematic plan view of the container wall with the tab
removed showing the relationship between the peripheral edge of the
guard and the score line.
FIG. 7 is a top plan view of a can end blank.
FIG. 8 is a fragmentary sectional view taken along line 8--8 of
FIG. 7.
FIG. 9 is a sectional view taken on an axial plane and illustrating
the tooling for forming a dimple and for coining the connecting
wall.
FIG. 10 is a sectional view taken on an axial plane showing the
tooling for converting the dimple into a hollow rivet and for
formation of the rib.
FIG. 11 is a sectional view taken on an axial plane and
illustrating the tooling for initiating axial collapse of the rib
and axial compression of the radial sections.
FIG. 12 is an enlarged fragmentary sectional view taken on an axial
plane illustrating the axial compression of the container wall to
form two reverse bend sections.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1-5 illustrate an easy opening container 11 in the form of an
easy opening can. The container 11 includes a generally cylindrical
peripheral wall 13 of sheet material, the upper end of which is
closed by an easy opening container or end wall 15 which is
attached to the upper end of the peripheral wall by interlocking
flanges 17 and 19. The lower end or bottom of the peripheral wall
13 can be closed in any conventional manner such as by an end wall
intregral therewith or by an end wall which is attached to the
lower end of the peripheral wall in a conventional manner.
The peripheral wall 13 may be of conventional construction except
for an annular rib 21 which projects radially inwardly closely
adjacent and beneath the wall 15.
The easy opening container wall 15 is constructed of sheet material
such as aluminum or an aluminum alloy. The easy opening container
wall 15 has a line weakness in the form of a score line 23 which
defines a relatively large panel or tear portion 25 which can be
removed from the container 11. The panel 25 covers a major portion
of the area of the container wall 15 and has an inner or non-public
surface 26. The configuration of the score line 23 is described in
connection with FIGS. 4-6. An annular coined region 26a of reduced
thickness extends along the score line 23.
A tab 27 is attached to the panel 25 in any suitable manner such as
by a hollow rivet 29. Although the tab 27 could be of various
constructions, in the embodiment illustrated, it is of the type
disclosed in common assignee's copending application Ser. No.
64,291. The tab 27 is integrally constructed from a single piece of
sheet metal and generally includes a tab body or lever 31 and an
attaching portion or ear 33 which is connected to the tab body 31
by a connecting wall 35. The rivet 29 projects through the
attaching ear 33 to attach the tab 27 to the panel 25. The tab body
31 has a lifting end 37 and a rupturing flange 39 at opposite ends
thereof.
The tab body 31 has an outer reinforcing curl 43 which extends
substantially completely around the tab body except for the
rupturing flange 39. Adjacent the connecting wall 35, the curl 43
has legs 45 and 47 connected by a bend portion 49 which the latter
being engageable with the connecting wall 35. The bend portion 49
is round and acts to support the connecting wall during
manipulation of the tab.
An outer or marginal region of the panel 25 has the sheet material
thereof bent to form an outwardly opening reverse bend portion 51
and an inwardly opening reverse bend portion 53. The bend portion
53 has a smooth dull surface or outer peripheral edge 55 which lies
adjacent the score line 23. As shown in FIG. 2, the reverse bends
51 and 53 are joined to the score line 23 and to the panel 25,
respectively. The reverse bends 51 and 53 are interconnected by a
connecting leg 57 which forms an intermediate layer of the marginal
portion of the panel 25. As shown in FIG. 2, the reverse bend 53
lies axially inwardly of the score line 23.
More specifically, a marginal region of the panel 25 is bent to
form an upper layer 56 of sheet material, a lower layer 56a of
sheet material and the intermediate layer or connecting wall 57.
All of the layers 56, 56a, and 57 are annular and extend
continuously around the marginal portion of the panel 25. The
layers 56, 56a and 57 and the bends 51 and 53 form a guard bead. At
all locations along the score line 23 except for the region
adjacent the rupturing flange 39 (FIG. 2) the layers 56, 56a and 57
are substantially parallel, and the layers 56 and 56a are flattened
against the intermediate layer 57, as shown in FIG. 4. With this
construction, the intermediate layer 57 abuts the upper layer 56
over substantially the full length of the intermediate layer.
However, at the region of the score line 23 adjacent the rupturing
flange 39, the intermediate layer 57 is not bent into tight
supporting engagement with the upper layer 56. Rather, as shown in
FIG. 2, the intermediate layer 57 projects radially outwardly and
axially inwardly in extending from the bend 51 to the bend 53. With
this construction, the intermediate layer 56 is not backed up or
supported immediately axially inwardly of the score line 23. This
facilitates the initiation of severance of the sheet material along
the score line 23, i.e., the initial pop.
When the lifting end 37 of the tab 27 is raised, the connecting
wall 35 of the tab readily bends to allow the tab body 31 to pivot
relative to the attaching ear 33. This forces the rupturing flange
39 against the sheet material at a region of the score line 23 and
tends to force a peripheral segment of the layer 56 so engaged by
the rupturing flange 39 axially inwardly. If the intermediate layer
57 were in tight engagement with the inner face of the layer 56, it
would support the latter, and therefore resist the inwardly
directed force applied by the rupturing flange 39. However, with
this invention, the layers 56a and 57 are spaced axially at the
region axially inwardly of the rupturing flange 39 so that the
layer 56 is unsupported in this region. Accordingly, the region of
the score line 23 engaged by the rupturing flange 39 is ruptured
with about the same ease as though the guard bead were not
provided.
Upon continued pivotal movement of the tab body 31, the tearing of
the sheet material along the score line 23 continues to thereby
rupture a segment of the line of weakness. Such pivotal movement of
th tab body 31 also bends a paddle section 58 of the panel 25
inwardly into the container 11 to form an opening 58a (FIG. 3). The
inward pressure applied to the layer 56 by the flange 39 may tend
to bend the layer 56 into engagement with the layer 57 as shown in
phantom lines in FIG. 2. The tab 57 is then pulled outwardly to
rupture the remainder of the sheet material along the score line 23
thereby removing the panel 25 from the container 11.
The rupture of the sheet material forms a relatively sharp edge 59
on th panel 25 as shown in dashed lines in FIG. 2 and a relatively
sharp edge 60 on the container (FIG. 3). The dull surface or edge
55 preferably lies closely adjacent the sharp edge 59 to form a
shield or partial sheath therefor. In addition, the edge of the
panel 25 is thick because it is defined by the three layers of
sheet material 56, 56a and 57. These two factors combine to make it
extremely difficult to be injured by the sharp edge 59.
The rib 21 on the peripheral wall 13 preferably projects radially
inwardly so that the edge 55 of the paddel section 58 just clears
the rib 21 as the paddle section is bent inwardly of the container
11. As shown in FIG. 3, the rib 21 projects radially inwardly
through a location which is in substantial alignment with the sharp
edge 60. Thus, the rib 21 serves as a guard to make cutting contact
with the sharp edge 60 much more difficult.
To facilitate the initial pull of the tab 27, the present invention
provides certain relationships between the edge 55 and the score
line 23. With reference to FIG. 6, pivotal movement of the tab body
31 bends the paddle section 58 inwardly about a bend zone or line
58b. Although the bend line 58b is shown as a straight line in
FIGS. 1 and 6, obviously it may have other configurations. This
results in tearing of a segment of the score line 23 lying
intermediate points 58c and 58d which define the ends of such
segment and the ends of the bend line 58b.
The present invention orients the edge 55 and the score line 23 in
such a way as to achieve maximum protection from injury and to
facilitate the initial pull of the tab 27. To obtain maximum
protection, the edge 55 preferably lies slightly radially outwardly
of the score line 23 so that it can better protect the user against
injury from the sharp edge 59. On the other hand, it has been found
that if the edge 55 lies radially outwardly of the score line 23
adjacent the points 58c and 58d, the edge 55 tends to hang up on
the rim of the opening 58a (FIG. 3). Accordingly, this invention
provides for locating the edge 55 radially outwardly of the score
line 23 along substantially all of the score line except for the
regions of the score line adjacent the points 58c and 58d.
A preferred way of configuring and positioning the score line 23
and the edge 55 is shown in FIG. 6. The edge 55 is circular in
plan. The score line 23 contains a circular portion 23a which is
concentric with the edge 55. The circular portion 23a is a major
portion of the score line 23 and, in the form shown in FIG. 6,
extends for approximately 270.degree. of the score line. Obviously,
the circular portion 23 may extend through arcs other than
270.degree..
The score line 23 also includes a pair of arcuate sections 23b and
23c which, in the embodiment illustrated, extend through the same
number of degrees and have radii of identical lengths. The radii of
the arcs 23b and 23c are smaller than the radius of the circular
portion 23a, and for this reason each of the arcs 23b and 23c forms
a hump on the score line 23. The circular portion 23a terminates at
reference lines X--X and Y--Y. The arcs 23b and 23c intersect at
reference line Z--Z, which is a radial line along which the
rupturing flange 39 engages the score line 23, and terminate at
lines Y--Y and X--X, respectively.
With this construction, the edge 55 lies slightly radially
outwardly of the circular portion 23a as shown in FIGS. 4 and 6. At
and adjacent the points 58c and 58d, the edge 55 lies slightly
radially inwardly of the score line as shown in FIG. 5. At and
adjacent the rupturing flange 39 (reference line Z--Z in FIG. 6)
the edge 55 lies radially outwardly of the score line 23 as shown
in FIGS. 2 and 6. The location of the points 58c and 58d may vary
depending upon the manner in which the tab body 31 is manipulated.
Accordingly, it is preferred to have the edge 55 lie radially
inwardly of the score line 23 along regions of sufficient length to
accommodate all reasonable variations in locations of the points
58c and 58d.
In FIG. 6, the humps formed by the arcs 23b and 23c have been
exaggerated for clarity. In actual practice, the score line 23 may
appear to be substantially circular in plan. In the embodiment
illustrated, the arcs 23a, 23b and 23c have centers C1, C2, and C3,
respectively.
With the construction shown diagrammatically in FIG. 6, the edge 55
lies radially inwardly of the score line 23 and hence from the edge
60 (FIG. 3) at the points 58c and 58d. Accordingly, the edge 55
cannot hinder removal of the tear portion 25. The edge cannot even
where located radially inwardly of the score line 23 is
sufficiently close to the sharp edge 59 to afford substantial
protection. In addition, tongue injuries of the type described
hereinabove are less likely to be caused on the paddle section 58
because this portion is bent and not as easy to lick.
FIGS. 7-12 illustrate a preferred method of constructing the easy
opening container wall 15 shown in FIGS. 1-6. FIGS. 7 and 8 show a
can end blank 61. The blank 61 includes a peripheral attaching
flange 63, an axial wall 65 and a pair of radial walls or sections
67 and 69 which are axially offset and interconnected by a
generally axial or connecting wall 71. In the embodiment
illustrated, the section 67 and the wall 71 are annular, and the
section 69 is circular. The blank 61 may be formed into this
configuration with any suitable tooling.
FIG. 9 shows a first work operation in which a dimple 73 is formed
and in which the connecting wall 71 is coined to elongate the same.
In FIG. 9, the connecting wall 71 is squeezed between a lower
coining die 75 and an upper coining die 77 with the compressive
force being sufficient to cause thinning and consequent generally
axial elongation of the connecting wall 71. The elongation of the
connecting wall 71 facilitates formation of the reverse bends 51
and 53. Specifically, the dies 75 and 77 have coining surfaces 79
and 81, respectively, which coin the sheet material between
reference lines A--A and B--B. The lower coining die 75 also has
horizontal supporting surfaces 83 and 85 for supporting the radial
section 67 and an annular region 87 which extends between the
connecting wall 71 and the dimple 73. The tooling provides spaces
88 and 88a to accommodate the elongation of the connecting wall
71.
The dimple 73 is formed by a punch 89 and a cooperating die 91. The
punch 89 engages the sheet material of the section 69 and offsets a
zone of the same into a die cavity 93. Ultimately the offset sheet
material is engaged between the cooperating surfaces of the punch
89 and the die 91 to coin the sloping wall of the dimple. The
coined regions are generally those portions of the dimple 73 which
are shown in FIG. 9 as being compressively engaged. A dimple making
process which involves stretching and coining of the sheet material
is disclosed in common assignee's U.S. Pat. No. 3,638,597. The
annular region 87 is not coined during the work operation
illustrated in FIG. 9.
In the work operation shown in FIG. 10, the dimple 73 is converted
into a hollow rivet 95 and the connecting wall 71 is converted into
a shorter connecting wall or axial wall 97 and an annular expansion
rib 99 which lies between the wall 97 and the rivet 95. The wall 97
extends substantially axially whereas the connecting wall 71 (FIG.
9) is inclined or sloped relative to the axis of the blank 61. The
annular expansion rib 99 is closely adjacent the wall 97.
The dimple 73 is converted into the rivet 95 by a rivet punch 101
and a rivet die 103. An outer annular region of the dimple 73 is
collapsed and flattened between working faces 105 and 107 of the
punch 101 and the die 103, respectively. The punch 101 has a head
109 which is within the rivet 95 to assist the formation thereof,
and the rivet 95 is in a die cavity 111.
The expansion rib 99 is formed by stretching and deformation of the
sheet material of the connecting wall 71 by a punch 113 and a die
115. The punch 113 has a head 117 which engages the sheet material
and forces the same into a die cavity 119.
The wall 97 is formed from the upper regions of the connecting wall
71. This is accomplished by the punch 113, the die 115 and a tool
121. In addition, the die 115 cooperates with the tool 121 to bend
the sheet material at the juncture of the section 67 and the wall
97 so that the wall 97 extends in a substantially axial
direction.
In the work operation shown in FIG. 11, the score line 23 is formed
and an axial compressive force is applied to the expansion rib 99
by a pair of compression tools 125 and 127 to completely flatten
the expansion rib. The scoring operation can advantageously be
carried out by a scoring die 129 and by a tool 131 which supports
the section 67. A spring 130 urges the die 129 and the tool 127 in
opposite directions. In addition, a punch 135 is partially inserted
into the rivet 95.
The tool 127 and the die 129 are advanced relative to the tools 125
and 131. The tool 127 strikes the upper end of the expansion rib 99
to initiate axial collapse and radial expansion thereof. Radial
expansion of the expansion rib 99 moves the lower end of the axial
wall 97 radially outwardly with the wall 97 pivoting about regions
132. This creates a generally Z-shaped cross section with the wall
97 extending both axially and radially. In addition, as the scoring
tool 129 is relatively advanced, it applies an axial compressive
force to the radial sections 67 and 69 with the result that the
wall 97 becomes more inclined relative to the axis of the blank 61
in the manner shown in FIG. 7. The expansion rib 99 is completely
collapsed in the work operation of FIG. 11.
During the operation shown in FIG. 11, the sheet material adjacent
the ultimately formed score line 23 is confined by the tool 131 and
the scoring die 129. As the die 129 and the tool 131 relatively
advance, the sheet material between the die 129 and the tool 131 is
compressively engaged to hold the section 67 in position and to
form the score line 23. At the end of the stroke the sheet material
radially outwardly of the score line 23 is coined by a coining face
132a, and this further tends to hold the section 67 in positin
during the last bit of radial expansion of the expansion rib in the
operation of FIG. 11. Ordinarily, the material radially inwardly of
a point X will be thinner than the material radially outwardly of
the score line 23 as a result of the coining operation of FIG. 9,
and consequently the face 132a will not ordinarily coin the
material radially inwardly of the score line.
By confining and compressively engaging the sheet material adjacent
and along the score line 23 to prevent movement thereof, stresses
of the type which might create tiny cracks or openings in the sheet
material along the score line are less likely to occur. In
addition, slight coining adjacent the score line 23 is believed
beneficial to the characteristics of the sheet material along the
score line.
FIG. 12 illustrates the next work operation in which the radial
sections 67 and 69 are moved toward each other with consequent
collapse of the wall 97 to form reverse bend sections 51 and 53
substantially as shown in FIG. 2. During the work operation of FIG.
12, the blank 61 is retained between tools or workholders 137 and
139, and the punch 141 is received within the rivet.
A compression tool 143 is moved upwardly and cooperates with the
tool 139 to at least partially collapse the wall 97 (FIG. 11) to
thereby form the reverse bends 51 and 53. Specifically, the
compression tool 143 has an annular working face 147 which is
continuous and planar except for a peripheral segment of the tool
143 at which a radial shoulder 149 and an axial shoulder 151
cooperate to define a recess 153. The recess 153 is formed at the
periphery of the tool 143 and extends circumferentially for a very
short distance.
The recess 153 increases the spacing between the tools 139 and 143
over what it would be without the recess. Accordingly, the sheet
material is not compressed as much by the tools 139 and 143 at the
recess 153 as it is where the recess does not exist.
SPecifically, the tools 139 and 143 squeeze and completely collapse
the wall 97 to form the configuration shown in FIG. 4 at all
locations which do not confront the recess 153. This squeezing
action of the tools 139 and 143 converts the regions 132 (FIG. 11)
into the bends 51 and 53, respectively, and the wall 97 (FIG. 11)
into the intermediate layer 57 as shown in our copending
application referenced hereinabove.
At the recess 153, the greater spacing between the tools 139 and
143 makes it possible for the layers 56, 56a, and 57 not to be
folded tightly against each other. At the beginning of the work
operation of FIG. 12, the layer 56 is supported from above by a
flat annular working face 156 of the tool 139, and the layer 56a is
unsupported from below. Accordingly, the relative advance of the
tools 139 and 143 forces the unsupported layer 56a into the recess
until the bend 53 engages the shoulder 149. This prevents the
intermediate layer 57 from being bent up tight against the upper
layer 56. This leaves a space 155 between the layers 56 and 57
along the circumferential length of the recess 153 as shown in FIG.
12. Thus, the circumferential dimension of the recess 153 should be
selected in accordance with the desired circumferential dimension
of the cross section shown in FIG. 12, i.e., the circumferential
dimension of the interruption of the guard bead. The tool 143 also
cooperates with a pressure pad 157.
Some ofthe material of the connection wall 71 (FIG. 8) is used to
form the reverse bends 51 and 53. Because the connecting wall 71
has been thinned, the reverse bends 51 and 53 are more easily
formed and are less likely to have cracks.
Following the work operation of FIG. 12, the tab 27 (FIGS. 1 and 2)
can be attached to the blank 61 by heading of the rivet 95 to
thereby convert the latter into the rivet 29 (FIGS. 1 and 2).
Thereafter, the resulting easy opening container wall can be
attached to the container 11 as shown in FIG. 2.
Although the method shown in FIGS. 7-12 is particularly adapted for
making an easy opening container wall of the type shown in FIG. 2,
it may be used in other instances where it is desired to form a
double fold or double reverse bend sections.
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 wihtout necessarily
departing from the spirit and scope of this invention.
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