IE47576B1 - Improvements in and relating to end closures for containers - Google Patents

Description

IMPROVEMENTS IN AND RELATING TO END CLOSURES FOR CONTAINERS.

This invention relates to an end closure for a container, for example a beverage or beer container, having a push tab for ease of opening the container.

According to the present invention, there is provi5 ded an end closure for a container comprising a panel having an outer peripheral connecting rim and a portion in which an aperture is formed, an underfold edge of the panel at least partially surrounding and defining the aperture and an underfolded edge portion lying in a plane at the underside of the panel, a push tab filling the aperture in said panel to close the aperture, the tab including a peripheral edge substantially directly underlying the said underfolded edge of the panel, a line of separation (as herein defined) between the panel and the push tab being disposed immediately beneath the underfolded edge portion of the panel, and means retaining said push tab peripheral edge in continuous contact with said underfold edge portion whereby to close said aperture, said retaining means being yieldable under manual pressure to displace the tab peripheral edge from the underfolded edge portion of the panel.

Further according to the present invention, there is provided an end closure of unitary construction for a substantially cylindrical container, said closure comp25 rising a radially outer lid section and a radially inner, - 3 elongate, gate panel formed in the lid section, said gate panel being formed out of the thickness of said end closure and extending in a radial direction from an inner end in the plane of and adjacent to the centre of said closure and terminating in an outer, rounded, end adjacent to and beneath the edge of said outer lid section surrounding the gate panel, said gate panel having opposed edges diverging outwardly in radial directions away from the inner end and the panel being disposed beneath the plane of said outer lid section at the aperture boundary in said outer lid section, and an underfolded edge portion defining a continuation of said outer lid section with the underfolded edge in surrounding relation to the aperture and extending continuously along and substantia15 lly directly above the opposed edges and outer end of said gate panel, a line of separation (as herein defined) being formed between said gate panel and the underfolded edge portion at least along the outer end and a portion of each of the opposed edges, the line of separation being disposed immediately beneath the folded edge portion of the lid section whereby to permit inward displacement of said gate panel away from said outer lid section so as to open said aperture, and sealing means serving to seal the line of separation prior to said inward displace25 ment.

Still further according to the present invention, - 4 there is provided a method of forming a convenience opening In a container end closure comprising the steps of (1) providing a sheet of metal to form the end closure having a central panel and surrounding rim, (2) deforming a portion of the central panel in a direction away from the plane of the central panel to form an inner, offset, gate panel and a wall section interconnecting the gate panel and central panel, (3) applying a force, in a direction opposite to 10 the first-mentioned direction, to said inner gate panel whereby to form an elongate medial rib therein, (4) folding by compressing the wall section in a sense tending to flatten the rib of the gate panel to cause said wall section to be compressed into a tight15 ly-folded head which undergoes an outward reversal from the central panel extending into an inward reversal into the gate panel, (5) shearing through the inward reversal of the wall . section directly beneath the outward reversal until a line of separation ( as herein defined) is formed betweeen the gate panel and the wall section, the material of the sheared inward reversal being displaced in a direction away from the line of separation, and (6) applying retaining means to the line of separ25 ation whereby to.seal said line.

Still further according to the invention, there is - 5 provided an end closure for a container comprising a lid section having a peripheral connecting rim and a portion including an aperture, an underfolded edge portion at least partially surrounding and defining the aperture and an underfolded edge portion extending in a plane at the underside of said lid section, a gate panel including a main body traversing the aperture in said lid section to close the aperture, a peripheral edge of the gate panel substantially directly underlying the said underfolded, edge, a line of separation (as herein defined) formed between said peripheral edge of said gate panel and the underfolded edge portion of the lid section and lying directly beneath the said underfolded edge portion, said main body being offset above the plane of said outer peripheral edge of the gate panel substantially to fill the aperture in said lid section, and means retaining said gate panel in continuous contact with said underfolded edge portion along said line of separation whereby to close and seal said aperture, the retaining means being yieldable under manual pressure to move the gate panel away whereby to open said aperture.

By the expression line of separation as used herein there is meant a physical separation which exists between the tab or gate panel and the underfolded edge portion prior to the application of pressure thereto to open the aperture, in contradistinction to an arrangement in which “ 6 the two components remain, prior to use, integrally connectedby a line of weakness which itself shears on application of pressure.

The line of separation may be interrupted by an 5 integral connection between the tab or gate panel and the lid section or end closure panel to form a hinge.

A broad reinforcing or stiffening area may be defined out of the thickness of the end closure which includes a main stiffening area formed in a radial dire'ct10 ion away from the gate panel and relatively narrow divergent portions flanking opposite sides of the gate panel. The gate panel itself 'may be provided with a button or raised pressure pad adjacent to one comer of the leading end to assist in initiating inward displacement of the gate panel. In one modification, it has been found that the entire tab or gate panel can be drawn or raised through the recess in the lid except for the outer peripheral edges which remain beneath the surrounding edge of the lid; and a rib or depression may be formed in the raised tab to define a hinge line which will encourage the gate panel to be symmetrically displaced away from the end closure more uniformly along opposite sides as it is progressively opening in response to an individual pressing downwardly upon the panel. The co25 operative disposition and arrangement of the stiffening - 7 areas, rib and pressure pad permits formation of a gate panel in which the sides of the panel diverge away from an inner hinged section and intersect with relatively sharply angled, converging edges forming the leading or outer end of the gate panel where separation is to be initiated. The leading end of the modified gate panel is basically of triangular configuration having relatively straight edges intersecting one another at a common point adjacent to the outer peripheral rim of the can and intersecting the divergent sides at right angles so as to form the broadest possible liidth at the pour opening while being capable of withstanding the pressure of the contents of the can.

The invention will now be particularly described, by way of example onl^, with reference to the accompanying drawings in which:Figure 1 is a plan view of one form of end closure with easy opening push tab; Figure 2 is a perspective view of the push tab or gate panel when viewed from the underside of the end closure; Figure 3 is a plan view, to an enlarged scale, of the form of push tab illustrated in Figures 1 and 2; Figure 4 is a sectional view taken on line 4-4 of * Figure 3; Figure 5 is another sectional view taken on line 5-5 of Figure 4; Figure 5A is a fragmentary sectional view enlarged and illustrating the line of separation between the gate panel and end closure; Figures 6 to 10 are fragmentary sectional views 5 showing the successive steps followed in the formation of the form of gate panel illustrated in Figures 1 to 5; Figure 11 is a plan view of a modified form of the present invention; Figure 12 is a plan view of the modified form 10 shown in Figure 11 when viewed from the underside of the end closure; Figure 13 is an enlarged cross-section ' taken on line 13-13 of Figure 11; Figure 14 is another cross-sectional view taken on 15 line 14-14 of Figure 11; Figure 15 is a plan view of still another modified form of end closure in accordance with the present invention characterised by having a transverse depression formed out of the raised body of the gate panel; . Figure 16 is a plan view of the underside of the modified form of end closure shown in Figure 15; and Figure 17 is a cross-sectional view taken on line 17-17 of Figure 15.

Referring in detail to the drawings, a metallic end closure 10 is illustrated in Figure 1 and in accordance with conventional practice comprises a substantially flat central panel 12 of circular configuration having an outer connecting rim or flange 14. As best seen from Figure 4 the rim 14 conventionally includes an upstanding wall section 15 commonly referred to as a chuck wall and an outwardly disposed downwardly and reverse folded bead 16 which is adapted in association with the chuck wall to receive the upper open edge 18 of a generally cylindrical container body or can so as to completely seal off the end of the can. In addition, the central panel or lid section 12 may suitably include a peripheral groove 20 extending annularly' around the panel or lid 12 inwardly of the outer connecting edge 14.

In accordance with the illustrated embodiment, a tear-open tab or gate panel 22 is formed out of the thickness of the central panel 12 to extend radially from the centre of the panel 12 to a point adjacent to and just inwardly of the peripheral groove 20. If desired, the gate panel may be flanked on opposite sides by suitable embossing represented in Figure 1 in the form of arrows 24.

Referring in more detail to Figures 2 to 5A, the illustrated form of gate panel 22 is formed out of the material of the central panel 12 so as to be displaced directly beneath the plane of the panel 12 and is of generally U-shaped configuration having opposite straight sides 25 and 26 diverging away from one another slightly in an outward radial direction from the inner end of the panel leaving a hinge portion 28 in a manner to be described and term10 inating in an outer curved end 30. The gate panel also includes a convex medial rib 32 extending in a rad ial direction from the inner end or hinge portion 28 to merge into divergent rib portions 33 and 34 adjacent to the outer end 30, the ribs being raised ahove the plane of the opposite edges 25 and 26 of the gate panels so that at their highest point the ribs are in the plane of the lid section or panel 12. In turn, opposite edges 25 and 26 as well as outer surrounding edge 30 of the panel are spaced inwardly of the lid or panel section 12 by an outer protective bead in the form of an underfold 36, as best seen from Figure 5A . The fold 36 undergoes a downward and outward reversal from the plane of the lid section 12. As will become apparent from the method of making the gate panel hereinafter described, normally the fold would continue into a downward and inward reversal 88 into the plane of the outer edges of the gate panel. However, in the formation of a line of separation designated at 40 between the gate panel 22 and central panel 12, that material form5 ing the lower portion of the fold 38 is sheared away from the underfold into the position as illustrated at 38' leaving a recessed area or corner of substantially right angle configuration between the outer peripheral side edge 42 of the gate panel and the underfold 36 of the lid. The line of separation is disposed substantially inmediately beneath the fold edge 36 as can be seen in Figure 5A. Although not shown, this area is filled with retaining means in the form of a sealant for example in the manner in United States Patent NO. 3,794,206.

From the foregoing, it will be seen, therefore, that Lhe gate panel extends from a hinge section at its inner end 28 in the plane of the lid or central panel 12 radially outwardly and inclined downwardly into outwardly divergent, opposed side edges 25 and 26 and outer surrounding edge 30, the gate panel being separated from the central panel by a downward and outward underfolded portion 36. In opening the can, downward pressure exerted manually by the thumb or finger upon the gate panel 22 adjacent to its outer curved end 30 and most desirably at the intersection of the rib sections 32, 33 and 34 will cause the panel to be hinged downwardly away from the central panel along the line of separation 40 so as to form an access opening into the interior of the can. The moment force applied about the inner end 28 of the gate panel will cause the gate panel to be hinged downwardly about this point but remain intact with the central panel. In this relation, the underfold 36 has asy00^ protective bead or drinking edge around the peripheral edge of the lid surrounding the gate panel to avoid injury to the thumb or finger in opening and of course to prevent cutting or discomfort in drinking from the can.

As shown in Figure 2, it is also highly desirable that the outer protective bead or underfold 36 taper inwardly toward the inner terminal end of gate panel at opposite side edges so as to form a gratluul reduction in thickness of the protective bead or in oLher words a gradual transformation between the plane of the central panel 12 into the downwardly displaced plane of the opposite side edges 25 and 26 of the gate panel 22.

As described'Lhe end closure lends itself particularly well to high volume mass production while maintaining or holding - 13 47576 extremely close tolerances and pel'.lifting manufacture in a minimum number ot steps. According to the preferred method or practice of carrying out the present invention, the central panel 12 is formed out of a metal sheet, such as aluminum or steel, as represented at 50 in Figure 6, and which has an outer marginal region bent to form an outer connecting edge or rim 14 and inner concentric groove 20 formed in a conventional manner. As illustrated in Figures 6 and 7, the shell 50 is securely clamped between outer generally annular workholders 52 and 53, the lower holder 53 being retractible, such as, by means of resistance springs or nitrogen filled cylinders so that the outer surrounding portion of tlie panel or blank may be forced downwardly as shown with respect to the original plane of the central panel as represented at 50. Simultaneously the initial step of forming the gate panel 22 is carried out by causing the inner punch 54 to advance downwardly toward tlie inner die 55 in forming the medial ribs 32, 33 and 34 and outer surrounding wall section 36 as well as inclined wall section 28 at the inner end portion of the gate panel.

In the initial and following steps, it should be understood that the central panel 12 is disposed upside down and the gate panel is formed by drawing the shell downwardly as described. In tlie initial steps of drawing or axially displacing a portion of the material in forming the gate panel 22, the depth of the draw is such that the outer edges or corners of the panel 25, 26 and 30 are displaced at least three times the thickness of the panel, and the rib 32 is displaced approximately twice the thickness of the panel to afford sufficient material for folding the wall sections 36' in the next successive stage while flattening the rib to an extent sufficient to leave some degree of convexity as illustrated in Figures 1 to 5Λ.

In the next successive stage, the panel or blank 50 is - 14 clomped between outer workholders GO and 62 with the. inner gate panel 22 interposed between an upper punch 63 and lower punch 64, the punches 63 and 64 being driven in opposite directions toward one another to partially flatten the medial rib 32 and cause outward lateral spreading of the metal toward the wall section 36 as the upper punch 63 is urged downwardly to fold the wall section upon itself into a lower fold configuration 38 as previously described with reference to Figure 5A. In this stage, in folding the wall section it is also coined or compressed only to a degree sufficient to insure that it is of uniform thickness around the edge as a preliminary to the final shearing operation. Furtiier the rib section 32 is partially flattened to the degree illustrated in Figure 9 by the convex surface portion 65 and complementary concave surface portion 66. In this way, the apex of the rib 32 is in the plane of the central panel except at the inner end 28 where the rib is fully flattened. As best seen from Figure 2, the lower fold section 38 in the area adjacent to the inner end gradually tapers toward the inner end as a result of the lesser amount of metal available in that area from flattening of the rib 32.

In the final stage of the gate panel forming operation, the blank 50 is interposed between outer workholders 70 and 71, and the gate panel section 22 is interposed between an upper shearing punch 72 and a lower die 74. The shearing punch is characterized by having a central recessed area 75 and an outer, downwardly projecting shearing portion 76 of generally U-shaped configuration corresponding to the configuration of the gate panel, for example as illustrated in Figures 1 to 3, with the inner corner or edge 77 of the shearing tool being slightly relieved; i.e., the inner surface is inclined to be at an angle less than 90° so that in shearing through the lower fold 38, it will - 15 not frictionally engage the material behind the shearing edge 77 and will further tend to force the metal as it is sheared away from the triple fold against the undersurface of the blank 50. The shearing operation is carried out so that the lower fold portion is completely removed from the full thickness of the gate panel so as to form the desired line of separation 40 between the gate panel 22 and folded portion 36.

Once sheared, it may be desirable to force the gate panel to the urged or biased against the underside of the center panel at its line of separation; and when the central panel is suitably embossed with additional fibbing or indicia such as the arrows 24 shown in Figure 1, the gate panel may be struck along the rib portion so as to cause the outer edges of the gate panel to be urged against the undersurface of the center panel.

It will be further apparent that various conventional sealants are applied in a well-known manner to seal the gate panel 22 against the central panel 12 prior to opening.

In the modified form of invention shown in Figures 11 to 14, like elements of the end closure 10' are correspondingly enumerated; namely, a central panel 12 of generally circular configuration having an outer connection rim or flange 14 and a peripheral groove 20 - 16 extending around the panel 12 just inwardly of the connecting edge 14. A modified form of tear-open tab or gate panel 22’ is formed out of the thickness of the central panel 12 with the major axis of the gate panel 22' extending radially from the center of the panel 12 to a point adjacent to and just inwardly of the peripheral groove 20. - 17 47576 Preliminary to describing the modified form of gate panel 22', it will be noted that the main or central panel 12 is also modified by provision for a broad reinforcing or stiffening area generally designated at 80 and which is of generally V-shaped configuration as viewed in the plan views of Figures 11 and 12.

The area 80 is formed out of the thickness of the central panel so as to be raised above the plane of the panel 12 and define a relatively broad reinforcing section 81 tapering in a direction away from the center of the panel 12 toward the closed end of the Vee as represented at 82. Opposite sides of the Vee essentially define divergent fingers 83 which flank opposite sides of the gate panel 22' and leave a narrow spacing 84 which is of generally U-shaped configuration and of uniform width between the opposite sides of the gate panel and the insides of the stiffening area 80.

Now considering the particular configuration of the gate panel 22', it is provided with opposite straight sides 85 and diverging away from a common, generallyCL-shaped center portion and extending in an outward radial direction for intersection with leading convergent straight edges 88 and 89 at the leading or outer end of the gate panel adjacent to the groove 20. The convergent edges 88 and 89 meet at a common point of intersection at the forward extremity of the gate panel and also intersect with the sides 85 and 86, respectively, to define corners 91 therebetween. Λ generally convex medial rib 92 extends in a radial direction along the major axis of the gate panel and for the greater length of the panel but terminates at a point just inwardly of the corners 91, the rib 92 being formed out of the material of the gate panel and being raised above the plane of the opposite side edges 85 and 86, as best seen from Figure 13, so as to define a stiffened area centrally of the panel.

In addition, a pressure pad 94 is formed out of the 47376 - 18 material of the gate panel so as to be raised above its plane at a paint adjacent to the comers 91, the cross-sectional configuration of the pressure pad being illustrated in Figure 14. In essence, the pressure pad 94 de5 fines a button or pressure point against which localized thumb or finger pressure is applied to initiate displacement of the gate panel inwardly away from the main panel 12.

Unlike the first form of invention, the gate panel 22' is displaced downwardly or inwardly from the plane of the central panel 12 uniformly throughout its peripheral extent, as opposed to merging into the plane of the central panel at the inner or central hinge section, such as, that illustrated at 28 in Figure 1. Again, however, an outer protective bead in the form of an under fold 36' extends between the outer peripheral edge of the gate panel and the surrounding edge of the central or main panel 12 so as to undergo a downward and outward reversal from the plane of the panel 12 into a single thickness of metal separating the gate panel 22' and central panel 12; and an area of separation designated at 40' extends between the gate panel 22 and central panel 12, the area of separation once again being formed by shearing a lower portion of the fold 38' away from the underfold and forcing the displaced metal outwardly against the underside of the panel 12. The recessed area left as a result of upward shearing of the metal is filled with a sealant or hot melt S, again in the manner descrihed in the first form. It should be stressed in this connection, however, that the line of separation of the gate panel from the outer protective bead 36 is interrupted at the central or hinge point 87 so that ( when the gate panel is displaced inwardly along the line of separation it will bend inwardly about the hinge section and will not he separated at that point from the central panel.

In still another modified form as illus47576 - 20 trated in Figures 15 to 17, like parts are once again corresponding ly enumerated. In this form, the central panel 12 is provided with a broad reinforcing area 80 in surrounding relation to still another modified form of gate panel 22''. The formation of the stiffening area 80 and of an outer protective bead and area of separation 40' between the gate panel and underfold of the central panel corresponds to that described with reference to Figures 1 to 5Λ or Figures 11 to 14. However, once the gate panel is displaced downwardly beneath the plane of the center panel 12 and prior to shearing of the opposite side edges 85, 86 and 88, 89,/the gate panel 22'' is displaced upwardly into the plane of the center panel 12 while displacing an intermediate transverse cross-section of the panel downwardly to form a concave depression or crossbeam 95 in the gate panel 22'. It will be noted that the displacement of the gate panel in an upward direction into the plane of the center panel will form a slight upward bend at the juncture of the gate panel with its outer peripheral edges, as indicated at 98 in Figure 17, throughout the entire periphery of the panel so that the outer peripheral side edges 85, 86 and the leading edges 88 and 89 may bp sheared to form an area of separation therebetween in the same manner as described with reference to the first and modified forms of invention. Furthermore, formation of a transverse rib or depression 85 intermediately of the gate panel will in effect separate the gate panel 22' into adjoining raised tab sections 99 and 100. The depth of the depression 95 is such as to be disposed in the plane of, and to merge into, the outer protective edges 85, 86 and 88, 89 and 98.

In the same manner as described with reference to the modified form of Figures 11 to 14, a pressure pad 94' is formed out of the thickness of the gate panel so as to be disposed slightly above the plane of the gate panel 22'' and center panel 12. In • - 21 this form, the pressure'pad 94' ir· located at or contiguous to the forward extremity 90 defined by the intersection of the leading edges 88 and 89 so that localized pressure applied by the finger or thumb at that point will initiate tearing or downward displace5 ment of the gate panel away from the center panel at the forward extremity of the gate panel 22'. A sealant S is applied to the sheared section formed at the area of separation between the gate panel and center panel in the same manner as described in tiie first form or modified forms so that the gate panel is nor10 mally retained in sealed relation to the underfolded edge or protective bead 36' of the center panel.

A number of important advantages accrue from the formation of the gate panel 22'* so as to be defined as the raised tab portions 99 and 100 separated by the transverse rib 95; ’for in15 stance, the tab portions 99 and 100 will in general increase the strength or rigidity of the gate panel and better resist any pressure build-up in the can, will discourage any build-up of dirt or foreign particles which might otherwise collect in the recessed area between the gate panel and center panel, anti will nuke the entire gate panel more readily accessible for application of downward pressure by the finger or thumb. The concave depression 95 further cooperates with the raised tab sections 99 and 100 in providing a weakened section or intermediate hinge to better promote initial tearing or separation of the forwardmost tab section 100 away from the center panel so that initial displacement of the forward tab'section away from the panel 12 will permit venting or release of any pressure build-up in the can as a preliminary to displacing the rearward can section downwardly away from the center panel 12. If desired, the concave depression 95 may also be coined or thinned to some degree in order to provide a weakened hinge section at that point without weakening the overall strength of the gate panel.

From tlie foregoing description of the method and sequence of operations followed in formation of the gate panel it will be seen that the gate panel can be formed out of the wall thickness of the center panel with an outer protective edge initially in the form of a triple fold and which is converted to a single fold by shearing away the lower portion of the fold which is directed inwardly into the gate panel. Use of a shearing tool in this manner not only affords greatly increased accuracy and reliability in formation of the desired line of separation but minimizes dulling of the cutting edge of the shearing tool in that the tool itself is much wider and minimizes concentration of forces along one sharpened cutting edge or line.

For the purpose of illustration and not limitation, easy-open, convenience ends made according to the hereinbefore described method may be suitably composed of an aluminum alloy, such as, 304II19, 50821119 or 5182 aluminum alloys having a thickness on tlie order of .013 inch to .014 inch; or can also be composed of various steel materials such as a double reduced D-RT4 ninety-five pound steel. In the initial draw or axial displacement as shown in Figures 6 and 7, the depth of draw as illustrated is on the order of six times the thickness of tlie material and the displacement in the center along the apex of the rib on the order of four times the thickness. In the next stage of folding and compressing the wall section as shown in Figures 8 and 9, the wall section is most desirably tightly folded so as to be approximately three times tlie thickness of the material and is coined along the fold to assure a uniform cut in the subsequent shearing operation. In the shearing operation as disclosed in Figure 10, most desirably the shearing tool severs the gate panel from the fold at the inside point of reversal as best seen from Figure 5A so that a minimum amount of material is displaced while assuring a fairly clean line of separation between the gate panel and underfold 34. In this connection, the recessed area formed is well suited for application of a sealant which will fill in the recessed area and flow into the space formed along the line of separation between the gate panel 32 and underfold 34. Further to assure a continuous line of separation along the opposite side edges and rounded edge of the gate panel, most desirably the shearing tool will pass or advance to a limited extent into the underfolded section past the line of separation 40.

It will be appreciated from the foregoing that the unique method of manufacture as well as the resultant gate panel construction lends itself well to various configurations and sizes particularly in can lid manufacture. Moreover, the location of the hinge section with respect to the rest of the gate panel and the central panel may be varied and for example the gate panel may be so constructed and arranged as to have the hinge section along the outer periphery of the lid with the rounded end 30 located radially inwardly of the hinge. The fold or protective bead as described is interrupted both in the sense that it terminates on opposite sides of the hinge section or plane of the central panel and is sheared away in forming the line of separation. In this respect, the underfold may be formed endlessly so as to completely encircle the gate panel without leaving an interrupted hinge section in the specific manner described, if for example it is for any reason desirable to permit complete detachment of the gate panel.

Accordingly, it is to be understood that various modi30 tications and changes may be made in the preferred form of push-tab end as described as well as the method of making same without - 24 departine from the scope of the invention as defined by the appended claims.

Claims (15)

1. An end closure for a container comprising a panel having an outer peripheral connecting rim and a portion in which an aperture is formed, an underfolded edge of the panel at least partially surrounding and defining the aperture and an underfolded edge portion lying in a plane at the underside of.the panel, a push tab filling the aperture in said panel to close the aperture, the tab, including a peripheral edge substantially directly underlying the said underfolded edge of the panel and the push tab.being disposed immediately beneath the underfolded edge portion of the panel, and means retaining said push tab peripheral edge in continuous contact with said underfolded edge portion whereby to close said aperture, said retaining means being yieldable under manual pressure to displace the tab peripheral edge from the underfolded edge portion of the panel.

2. An end closure according to claim 1, wherein said push tab includes a hinge portion forming a continuation of said panel downwardly into underlying relation to said underfolded edge portion, said underfolded edge portion terminating on opposite sides of said hinge portion and surrounding the aperture except along said hinge portion. - 26 3. An end closure according to claim 2, wherein said push tab has a convex rib extending along the tab radially outwardly from the hinge portion.

3. 5 4. An end closure of unitary construction for a substantially cylindrical container, said closure comprising a radially outer lid section and a radially inner, elongate, gate panel formed in the lid section, said gate panel being formed out of the thickness of said end 10 closure and extending in a radial direction from an inner end in the plane of and adjacent to the centre of said closure and terminating in an outer, rounded, end adjacent to and beneath the edge of said outer lid section surrounding the gate panel, said gate panel having 15 opposed edges diverging outwardly in radial directions away from the inner end and the panel being disposed beneath the plane of said outer lid section at the aperture boundary in said outer lid section aftdian underfolded edge portion defining a continuation of said 20 outer lid section with the underfolded edge In surrounding relation to the aperture and extending continuously along and substantially directly above the opposed edges and outer end of said gate panel, a line of separation (as herein defined) being formed between said gate 25 panel and the underfolded edge portion at least along the outer end and a portion of each of the opposed edges, the line of separation being disposed immediately be47576 - 27 neath the underfolded edge portion of the lid section whereby to permit inward displacement of said gate panel away from said outer lid section so as to open said aperture, and sealing means serving to seal the line of separation prior to said inward displacement. 5. An end closure according to claim 4, wherein said underfolded edge portion is defined by a tightly-folded section of metal undergoing a radially outward reversal from said lid section into a plane directly beneath said lid section.

4. 6. An end closure according to claim 4 or claim 5, wherein said line of separation is defined by a sheared metal section formed between the peripheral edge of the gate panel and said underfolded edge portion.

5. 7. Afl end closure according to claim 4, claim 5 or claim 6, in which said gate panel inclines downwardly from an inner end in the plane of said lid section to extend in a plane substantially parallel to and beneath the plane of said lid section.

6. 8. An end closure according to any one of claims 4 to 7, in which said gate panel includes a raised medial port47576 - 28 ion extending radially from the inner end toward the outer end thereof.

7. 9. A method of forming a convenience opening in a con5 tainer end closure comprising the steps of (1) providing a sheet of metal to form the end closure having a central panel and surrounding rim, (2) 'deforming a portion of the central panel in a direction away from the plane of the central panel to

8. 10 form an inner, offset, gate panel and a wall section interconnecting the gate panel and · central-panel; (3) applying a force, in a direction opposite to the first-mentioned direction to said gate panel whereby to form an elongate medial rib therein 15 (4) folding, by compressing the wall section in a sense tending to flatten the rib of the gate panel to cause said wall section to be compressed into a tightlyfolded bead which undergoes an outward reversal from the central panel extending into an inward reversal into 20 the gate panel, (5) shearing through the inward reversal of the wall section directly beneath the outward reversal until a line separation (as herein defined) is formed between the gate panel and the wall section, the material of 25 the sheared inward reversal being displaced in a direc47576 - 29 away franthe line of separation, and (6) applying retaining means to the line of separation whereby to seal said line. 10. A method according to claim 9, including the step of coining the folded wall section into a tightly-folded wall section of uniform thickness prior to the shearing step.

9. 11. A method according to claim 9 or claim 10, comprising deforming the central panel to form a wall section in outer surrounding relation to the gate panel except along an uninterrupted portion of limited extent in which the gate panel inclines downwardly away from the central panel.

10. 12. A method according to claim 11, in which the wall section tapers into the central panel on opposite sides of the uninterrupted portion.

11. 13. A method according to claim 12, in which said gate panel is of substantially U-shaped configuration and the uninterrupted portion is located adjacent to the centre of the central panel. - 30

12. 14. An end closure for a container comprising a lid section having a peripheral connecting rim and a portion including an aperture, an underfolded edge at least partially surrounding and defining the aperture, 5 and an underfolded edge portion extending in a plane at the underside of said lid section, a gate panel including a main body traversing the aperture in said lid section to close the aperture, a peripheral edge of the gate panel substantially directly underlying the said under10 folded edge, a line of separation (as herein defined) formed between said peripheral edge of said gate panel and the underfolded edge portion of the lid section, and lying directly beneath the said underfolded edge portion, said main body being offset above the plane of said outer

13. 15 peripheral edge of the gate panel substantially to fill the aperture in said lid section, and means retaining said gate panel in continuous contact with said underfolded edge portion along said line of separation whereby to close and seal said aperture, the retaining means 20 being yieldable under manual pressure to move the gate panel away whereby to open said aperture. 15. An end closure according to claim 14, wherein said gate panel includes a pressure pad defining a raised su25 rface area to assist in applying concentratedpressure to a localised area of said gate panel for displacement of the gate panel inwardly away from said lid section. 4757 6

14. 16. An end closure according to claim 14 or claim 15 wherein said gate panel is elongate and is formed with a rib extending transversely of the major axis of the gate panel so as to form a depression in said gate panel 5 intermediately between the inner and outer ends thereof.

15. 17. An end closure according to claim 14, wherein said main body is disposed in the plane of said lid section. 10 18. An end closure for a container, said closure being substantially as herein described with reference to any one of the embodiments shown in the accompanying drawings.