TAB WITH RIVET-RECEIVING AREA, METHOD OF FORMATION, AND TOOLING THEREFOR

Abstract

A method for manipulating a piece of material for use as a tab in conjunction with a container. The method includes accessing piece of relatively thin, sheet-like material and forming a hole in the piece of material. The method further includes performing a wiping operation to deform material adjacent to the hole, and performing at least one coining operation to flatten the deformed material. After the at least one coining operation the piece of material has an area of increased thickness adjacent to the hole, and after the at least one coining operation the piece of material has a generally straight inner portion at least partially defining the hole, where the generally straight portion extends at least about 20% of a height of the hole.

Claims

1. A method for manipulating a piece of material for use as a tab in conjunction with a container, the method comprising: accessing piece of relatively thin, sheet-like material; forming a hole in the piece of material; performing a wiping operation to deform material adjacent to the hole; and performing at least one coining operation to flatten the deformed material, wherein after the at least one coining operation the piece of material has an area of increased thickness adjacent to the hole, and wherein after the at least one coining operation the piece of material has a generally straight inner portion at least partially defining the hole, the generally straight portion extending at least about 20% of a height of the hole.

2. The method of claim 1 wherein the generally straight inner portion is straight and linear, and extends at least about 33% of the height of the hole.

3. The method of claim 1 wherein the deformed material, after the wiping operation but before the at least one coining operation, has an inner radius of less than about 5/1000.

4. The method of claim 1 wherein the area of increased thickness protrudes outwardly from a lower surface of the piece of material, and does not protrude outwardly from a top surface of the piece of material, with regard to a tab orientation when the tab is configured to be coupled to the container.

5. The method of claim 1 wherein the area of increased thickness has an upper curved portion and a lower curved portion with regard to a tab orientation when the tab is configured to be coupled to the container, and wherein an effective radius of the upper curved portion is less than an effective radius of the lower curved portion.

6. The method of claim 5 wherein upper curved portion and the lower curved portion are both located immediately adjacent to the generally straight inner portion, and wherein the effective radius of the upper curved portion is less than about 50% than the effective radius of the lower curved portion.

7. The method of claim 1 wherein the area of increased thickness has an upper curved portion, with regard to the tab orientation when the tab is configured to be coupled to the container, having an effective radius less than about 4/1000.

8. The method of claim 1 wherein the area of increased thickness has a thickness between about 1% and about 30% greater than at least one of the thickness of the piece of material during the accessing step, or the thickness of the piece of material, after the at least one coining step, at locations adjacent to but spaced away from the area of increased thickness.

9. The method of claim 1 wherein the area of increased thickness has a thickness between about 9.1/1000 and about 12/1000, and wherein the piece of material at locations adjacent to but spaced away from the area of increased thickness has a thickness of between about 9/1000 and about 9.5/1000 and less than the thickness of the area of increased thickness.

10. The method of claim 1 wherein the at least one coining operation includes a first, a second and a third coining operation, and wherein each coining operation reduces a radius of an upper curved portion of the area of increased thickness and increases the height of the generally straight portion.

11. The method of claim 1 the generally straight portion oriented is generally perpendicular to at least one of an upper surface of the area of increased thickness or an upper surface of the piece of material, with regard to the tab orientation when the tab is configured to be coupled to the container.

12. The method of claim 1 wherein the area of increased thickness has a generally flat lower surface oriented generally perpendicular to the generally straight inner portion.

13. The method of claim 12 wherein the generally flat lower surface extends in a direction parallel to at least one of an upper surface of the area of increased thickness or an upper surface of the piece of material, a distance of at least about 33% of a thickness of the piece of material, and wherein the upper and lower surfaces are upper and lower with regard to a tab orientation when the tab is configured to be coupled to the container.

14. The method of claim 1 wherein the area of increased thickness extends about an entire perimeter of the hole, and wherein the hole is circular in top view.

15. The method of claim 1 wherein the piece of material is in the form of the tab, wherein the tab is generally oval in top view and includes a front portion and a back portion located at opposite end thereof, wherein the back portion includes an opening therein and the front portion includes an opening formed therein with a peninsula positioned therein, wherein the hole is formed in the peninsula, and wherein the tab includes a rolled portion about an outer perimeter thereof.

16. The method of claim 1 further comprising coupling the piece of material to an end cap made of a relatively thin metal material via a rivet extending through the hole and coupled to the end cap, wherein the end cap has a main score line formed therein and defining a flap area, and wherein after the coupling step the tab is pivotable relative to the rivet about an axis oriented in a direction parallel to a plane of the end cap such that a front portion of the tab is pressable into the flap area to cause the main score line to tear along its length.

17. A system including a tab for use in connection with a container comprising: a generally oval tab body having a front portion and a back portion and made of a piece of relatively thin, sheet-like material; and a hole positioned in the tab; wherein the tab body includes an area of increased thickness adjacent to the hole, wherein the area of increased thickness has a generally straight inner portion extending at least about 20% of a height of the hole.

18. The system of claim 17 wherein the area of increased thickness has a thickness between about 1% and about 30% greater than a thickness of the tab body at areas adjacent to but spaced away from the area of increased thickness, wherein the tab body is generally oval in top view and includes a front portion and a back portion located at opposite end thereof, wherein the front portion includes an opening formed therein with a peninsula positioned therein and the back portion includes an opening therein, wherein the hole is formed in the peninsula, and wherein the tab body includes a rolled portion about an outer perimeter thereof.

19. The system of claim 17 further comprising an end cap made of a relatively thin metal material, wherein the tab is coupled to the end cap via a rivet extending through the hole and coupled to the end cap, wherein the end cap has a main score line formed therein and defining a flap area, and wherein the tab is pivotable relative to the rivet about an axis oriented in a direction parallel to a plane of the end cap such that a front portion of the tab is pressable into the flap area to cause the main score line to tear along its length.

20. Tooling for forming a tab comprising: a piercing toolset including a male punch and a supporting female structure, wherein the male punch is configured to extend through a tab or tab precursor and be closely received in the supporting female structure to thereby remove a piece of material from the tab or tab precursor and form a hole in the tab or tab precursor; a wiping toolset including a female wiping tool and a male wiping tool configured to be received in the female wiping tool to thereby form an area of deformed material of the tab or tab precursor positioned at or adjacent to an inner edge of the hole; and a coining toolset including a male coining tool and a female coining tool configured to compress at least part of the tab or tab precursor therebetween in an axial direction to perform coining operations on the area of deformed material of the tab; wherein at least one of: a) the male punch of the piercing toolset has a diameter less than 0.1260; or b) the supporting female structure of the piercing toolset has a diameter less than 0.1282; or c) the male wiping tool of the wiping toolset has a diameter greater than 0.1300; or d) the male wiping tool has an upper inner corner positioned adjacent to the deformed material of the tab or tab precursor during wiping operations, having a radius less than 0.0050; or e) the female wiping tool has an inner corner configured and positioned such that the deformed area of the tab or tab precursor is deformed about the inner corner during wiping operation, the inner corner of the female wiping tool having a radius of less than 0.0030; or f) the female coining tool has a central opening receiving the male coining tool therein, the central opening having a diameter of less than 0.1310; or g) the coining toolset has an upper inner corner positioned adjacent to the tab or tab precursor during coining operations, the upper inner corner having a radius less than 0.030; or h) the male coining tool has an upper outer corner positioned adjacent to the tab or tab precursor during coining operations, the upper outer corner of the male coining tool having a radius less than 0.0050.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0005] FIG. 1 is a perspective view of a can with an end cap;

[0006] FIG. 2 is a top view of the end cap of the can of FIG. 1;

[0007] FIG. 3 is a cross section taken along line 3-3 of FIG. 2;

[0008] FIG. 4 is a top view of the tab of the end cap of FIG. 2;

[0009] FIG. 5 is a cross section of the tab of FIG. 4, taken along line 5-5;

[0010] FIG. 6 is a detail view of the area indicated in FIG. 3;

[0011] FIG. 7 is a detail isolated view of the rivet receiving area of the tab of FIG. 6;

[0012] FIG. 8 is a side cross section showing a first step in the formation of the rivet receiving area;

[0013] FIG. 9 is a side cross section showing a second step in the formation of the rivet receiving area;

[0014] FIG. 9A is a detail view of the area indicated in FIG. 9,

[0015] FIG. 10 is a side cross section showing a third step in the formation of the rivet receiving area;

[0016] FIG. 11 is a detail view of the area shown in FIG. 10;

[0017] FIG. 12 is a side cross section showing a fourth step in the formation of the rivet receiving area;

[0018] FIG. 13 is a side cross section showing a fifth step in the formation of the rivet receiving area; and

[0019] FIG. 14 shows the tab of FIG. 13 being coupled to a rivet.

DETAILED DESCRIPTION

[0020] FIG. 1 illustrates a container body 8, such as a can or the like, having a tubular main portion 9, with a circular lid or end cap 10 coupled thereto. In one case the end cap 10 is formed separately and coupled to the main portion 9 of the container body 8 such that the lid or end cap 10 is coupled to and/or forms part of the container body 8, as will be described in greater detail below. The end cap 10 can include or be made of an end cap body 12 made of a relatively flat, sheet-like thin piece of sheet-like material, including metals such as aluminum, steel, aluminum alloys and steel alloys and the like. The end cap body 12 can be relatively thin and planar, in one case having a thickness of between about 8/1000 and about 8.5/1000. The end cap 10/end cap body 12 can be generally circular in top view so that the end cap 10 can be coupled to the generally cylindrical main portion 9 of the container body 8, but can have other shapes as desired.

[0021] The end cap 10/end cap body 12 can in one case have a center panel 14, a tapered countersink groove 16 extending about an outer perimeter thereof, and an outer curl portion 18 configured to fit about and be coupled to an upper flange (not shown) of the container body 8. The end cap 10/end cap body 12 can further have a deboss panel or depressed area 20, defined by a downwardly angled chamfer portion or edge 22.

[0022] The end cap 10 can have a main score line 24 and an anti-fracture score line 26 formed therein. The main score line 24 extends in a nearly closed loop shape in top view, having a generally kidney bean shape in the illustrated embodiment and defining a flap or flap area 28 therein. The flap 28 can also include a debossed section or a down bead 30 located in a center area of the flap 28 to provide increased stiffness to the flap 28. In the embodiment of FIGS. 1 and 2 the main score line 24 does not form a complete loop but leaves a gap, landed area or hinge area 32 through which the main score line 24 does not extend.

[0023] The main score line 24 can be a cut or area of displaced/removed material formed in the thickness of the end cap 10 to form a groove. The anti-fracture score line 26 extends parallel or generally parallel to the main score line 24 in top view. The anti-fracture score line 26 can be a cut or area of displaced or removed material to form a groove in the thickness of the end cap 10. The anti-fracture score line 26 can be formed at the same time as formation of the main score line 24, and can be provided to reduce stresses in the end cap 10 and/or main score line 24 during formation of the main score line 24.

[0024] The end cap 10 can have a generally oval-shaped tab 34 having a front end/tip 36 and an opposed back end/tip 38. The tab 34 can be coupled to the end cap body 12 via a rivet 40 extending through a hole or opening 48, but the tab 34 can be coupled to the end cap body 12 by various other devices and mechanisms. The back end 38 of tab 34 is configured to be manually raised and thereby pivot the tab 34 about the rivet 40, pivoting the tab 34 about an axis parallel to the plane of the end cap body 12, pushing or pressing the forward tip/end 36 of the tab 34 downwardly into the flap area 28. The flap 28 is then formed and folded downwardly about the hinge area 32 into the container body 8, as the main score line 24 tears or fractures along its length, thereby forming an opening through which the contents of the container body 8 can be dispensed.

[0025] The tab 34 can include a tab body 52 and have a back opening 42 formed through a back portion (adjacent the back end 38) and a front opening 44 formed through a front portion (adjacent the forward end 36). The openings 42, 44 can provide material saving and weight reduction. The tab 34 can include a peninsula 46 positioned in/adjacent to the front opening 44, and the hole or opening 48 is formed in the peninsula 46. The hole 48 is configured to receive the rivet 40, which also extends through and/or is fixedly coupled to, the end cap 10, to thereby couple the tab 34 and the end cap 10. As best shown in FIG. 5, the tab 34 can include a rolled portion 50 about an outer perimeter thereof to provide stiffening to the tab 34 and reduce exposure of sharp edges of the tab 34. The tab 34/tab body 52 can be made of or include a relatively flat, sheet-like thin piece of sheet-like material, including metals such as aluminum and aluminum alloys, or steel and steel alloys and the like, and can have a thickness of between about 9/1000 and about 9.5/1000 in one case, or less than about 15/1000 in one case and/or greater than about 6/1000 in another case.

[0026] As best shown in FIGS. 6 and 7, the tab 34 can have a rivet receiving area/stiffening area/area of increased thickness 54 extending around part (at least about 50% of a perimeter in one case, or at least about 75% of a perimeter in another case) or an entirety of the hole 48. In one case the stiffening area 54 has a thickness greater than areas or portions the tab body 52 at positions adjacent to and/or further away from the stiffening area 54. In one case the stiffening area 54 has at thickness at least about 1% greater in one case, or at least about 10% greater in another case and/or less than about 30% greater than: 1) the thickness of the piece of material 52 during the at the beginning of the hole-forming/stiffening process (e.g. at the time of the process of FIGS. 8 and/or 9, as described below) and/or 2) the thickness of the tab body 52/piece of material 52 at areas adjacent to but spaced away from the area of increased thickness 54 (e.g. area 59 of FIG. 7). The area of increased thickness 54 can extend laterally/radially (e.g. in the left-to-right direction of FIGS. 6 and 7) a distance at least 75% in one case, or at least about 100% in another case, of the height (or maximum height) of the area of increased thickness 54 (e.g. in the vertical direction of FIGS. 6 and 7).

[0027] The area of increased thickness 54 thus can have an increased thickness (in one case, in a direction perpendicular to an upper 43 and/or lower 45 surface of the tab body 52/piece of material 54/area of increased thickness 54) that is greater than about 0.1/1000 in one case, or greater than about 1/1000 in another case, and/or less than about 3/1000 in one case, compared to the thickness of the tab body 52 and/or area 59. Thus the stiffening area 54 can have a largest thickness in one case (e.g. in the vertical direction of FIG. 7) of at least about 9.1/1000 in one case, or at least about 10/1000 in another case, and less than about 12/1000 in one case. In the same or other cases, the stiffening area 54 can have a thickness less than about 0.5%, or in another case less than about 0.25%, different than the thickness of tab body 52 compared to positions 59 adjacent to and/or further away from the stiffening area 54, and thus can have a thickness of greater than about 6/1000 in one case, or greater than about 6.5/1000 in another case, or greater than about 9/1000 in another case, or less than about 15/1000 in another case. The stiffening area 54 can have an upper 47 and/or lower 49 surface that is parallel or generally parallel (within about 1 in one case, or with about 2.5 in another case) with each other, and/or compared to the upper 43 and/or lower 45 surface of the tab body 52/piece of material 52.

[0028] The stiffening area 54 can be desired to have sufficient thickness to provide stiffness and/or a sufficiently long straight, inner portion 60 (described below), but may not be desired to be unduly thick which could result in additional use of materials, leading to increase weight and/or cost. The stiffening area 54 can be positioned on or protrude toward (in one case, only toward) a lower side 56 (FIG. 5; opposite the top side 58) of the tab 34 (e.g. protrude away from the lower surface 45) with regard to the orientation of the tab 34 when the tab 34 is coupled to the end cap 10/container (e.g. on the same side of the exposed/crimped edges of the rolled portion 50 in one case), for reasons which will be described in greater detail below. Thus in one case the stiffening area 54 lacks an upper protrusion, and the upper surface 47 thereof is generally flat and planar and aligned with the upper surface 43 of areas of the tab body 52 away from the stiffening area 54 such as at area 59.

[0029] In one case, with reference to FIG. 7, the stiffening area 54 includes a straight/linear or generally straight/linear (accounting for manufacturing tolerances) inner portion 60 oriented perpendicular or generally perpendicular (in one case, within about 0.5 or in another case within about 1, and in another case within about 2.5) to an upper surface 43 and/or lower surface 45 of the tab body 52 (and/or relative to upper surface 47 and/or lower surface 49 of the stiffening area 54). The straight portion 60, which forms/defines a radially inner surface of the stiffening area 54/hole 48, provides good surface contact with the radially outer surface 62 of the rivet 40 (see FIG. 6). In particular, the radially outer surface 62 of the rivet 40 contacted by the tab 34 can also be straight or generally straight/vertically oriented, and in this manner the straight portion 60 thereby increases surface contact and frictional forces so that the tab 34 can grip the rivet 40 to reduce pivoting of the tab 34 about the rivet 40 (e.g. reducing pivoting of the tab 34 in the direction of arrow A of FIG. 2), and does not present sharp edges that may cause tearing of the rivet 40.

[0030] This frictional force helps to ensure the tab 34 remains in the desired orientation (shown in FIGS. 1 and 2) where the tab 34 can be operated to open the flap 28, and avoids the tab 34 pivoting about the rivet 40 to other positions. The straight portion 60 can extend at least about 20% in one case and/or at least about 33% in another case, and/or less than about 60% in another case, of the height of the inner edge of the hole 48/stiffening area 54. The straight portion 60 thus can have a length about 4.6/1000 in one case, and have a length at least about 3/1000 in one case and/or less than about 6/1000 in another case.

[0031] In one case, the stiffening area 54 has a generally flat lower surface 64 that is oriented perpendicular or generally perpendicular to the straight portion 60. The flat lower surface 64 can extends parallel or generally parallel to the upper 43 and/or lower 45 surfaces of the tab 34 (and/or the upper 47 and/or lower 49 surfaces of the stiffening area), for a distance of at least about 3/1000 in one case and/or less than about 6/1000 in another case, or between about 33% and about 66% of a thickness of the tab body 52 in one case, or less than 120% of the thickness of the tab body 52 in another case. The flat lower surface 64 helps to further provide surface-to-surface contact with a corresponding flat, horizontally-oriented surface 41 of the rivet 40 to increase frictional forces, and does not present sharp edges that may cause tearing of the rivet 40. The flat surface 64 may be desired to extend sufficiently long to provide sufficient frictional gripping, but may not be desired to extend too long which could result in excess material/weight.

[0032] With reference to FIG. 7, the stiffening area 54/hole 48/inner edge can have an upper curved portion/upper-inner radius/first radius 66 extending between the straight portion 60 and the upper surface 47 of the stiffening area 54, and a lower curved portion/lower radius/second radius 68 extending between the straight portion 60 and the lower surface 49 of the stiffening area. The upper portion 66 can have an average or effective radius of about 2/1000, or in one case between about 0.5/1000 and about 4/1000, or less than about 5/1000. In this case then the upper portion 66 can have an average radius of between about 5% and about 45% of a thickness of the tab body 52. It is understood that the upper 66 and/or lower portions 68 may not have a perfectly smooth or curved shape, and in this case the radius can be measured as an average radius for the various curved portions 66, 68, and/or the radius of a best fit circle segment (using a least square model in one case). In general, it can be desired to provide a relatively small radius on the upper portion 66 to maximize the length/height of the straight portion 60 to thereby ensure good gripping of the rivet 40, as outlined above.

[0033] The lower portion 68 can have an average or effective radius of about 4.5/1000, or between about 2/1000 and about 8/1000 in one case. In this case then the lower portion 68 can have an average radius of between about 20% and about 80% of a thickness of the tab body 52, in one case using the same calculation methods described above with regard to the radius of the upper portion 66. The lower radius 68 can in one case be between about 50% and about 100% greater than the upper radius 66. In general, the lower radius 68 should be sized to match the size of the corresponding radius 70 on the bottom of the rivet 40 to match the shape and provide strong frictional forces therebetween. Thus it may not be desired to make the lower radius 68 too small, which can provide an upper limit on the height/length of the straight portion 60.

[0034] In order to form the hole 48/stiffening area 54, the tab 34 (or tab precursor) is first provided as a piece of relatively thin, sheet-like material or the tab body 52, as shown in FIG. 8. At this stage, the piece of material 52/tab 34 can include or not include any or all of the back opening 42, the front opening 44, the peninsula 46, the rolled portion 50 or other features described above and shown herein. In any case, as shown in FIG. 8 the hole 48 (or a precursor thereof) is formed or pierced in the tab 34 by a piercing tool or toolset 72 that extends through the tab 34 and removes material (a circular piece of material in one case) to form the hole 48. This step can be carried out using a male punch 74 of the piercing toolset 72 positioned on one side of the tab 34 and a supporting female structure 76 of the piercing toolset 72 positioned on the other side of the tab 34 during formation of the hole 48, where the female structure 76 closely receives the male punch 74 therein.

[0035] The hole 48 (or precursor of the hole 48) of FIG. 8 can be smaller than the hole 48 in the end product. In one embodiment the hole 48 in the end product (e.g. as shown in FIGS. 1-5, 13 and 14) has a diameter of about 0.130 (+/5% in one case). The hole 48/hole 48 precursor formed in the step of FIG. 8 can have a diameter of about 0.124 in one case (+/5% in one case), or less than 0.126 in another case. It can be desired to make the hole 48/hole 48 precursor relatively small at this stage, as doing so enables additional material to be deformed/formed into the stiffening area 54, as will be described in greater detail below. Thus the hole precursor 48 in FIG. 8 can in one case have a diameter than is smaller than the end product hole 48 by less than about 20% in one case, or less than about 15% in another case, and/or greater than about 3% in yet another case. In one embodiment, the diameter of the male punch 74 (dimension B of FIG. 8) is 0.124 (+/1% in one case) (or less than 0.125 in one case, or less than 0.126 in another case), and the diameter of opening of the female structure 76 (dimension C of FIG. 8) is 0.126 (+/1% in one case, or +/3% in another case) (or less than 0.1280 in one case, or less than 0.1282 in another case).

[0036] Next as shown in FIGS. 9 and 9A, a wiping operation is performed to deform material surrounding the hole 48, and also simultaneously widen the hole 48 to or very close to (at or within about 1% diameter size in one case) its final size values as described herein. Thus at this step the hole 48 can be increased in diameter by about 5%, or in another case by between about 2.5% and about 8%. As can be seen the wiping step of FIG. 9 can be carried out using a wiping toolset 78 including a male wiping tool 80 positioned on one side (the top side, in the illustrated embodiment) of the tab 34 and a supporting female structure 82 positioned on the other side of the tab 34 (the bottom side, in the illustrated embodiment).

[0037] At this step an area of curved, deformed material 84 positioned at or adjacent to the hole 48 can be bent out of plane with the remainder or adjacent areas of the piece of material 52/tab 34. The deformed material 84 can be a precursor of the stiffening area 54. The female structure 82 can have a corner 79 on an outer surface thereof, about which the deformed material 84 is formed, thereby defining an inner corner 81 of the deformed material 84. The corners 79/81 may be relatively small, in one case having a radius or average radius or effective radius (defined using the methods described below) of less than about 5/1000 in one case, or less than about 3/1000 in another case, and about 2/1000 in one case, but greater than about 1/1000 in yet another case. Thus the corners 79/81 can in one case have a radius of about 22% of a thickness of the piece of material 52/tab 34, or in one case less than about 35% and/or greater than about 10% than the thickness of the piece of material 52/tab 34. The benefits of the relatively small radii 79/81 are described in greater detail below.

[0038] FIG. 9 shows the toolset 78 deforming material 84 toward/onto a lower side 56 of the tab 34/tab body 52 with regard to the illustrated orientation. However this orientation can be reversed, although as noted above it may be desired to ultimately have the stiffening area 54 on the underside of the tab 34 which can be achieved by simply inverting the tab 34.

[0039] The male wiping tool 80 can have a tapered (narrower) lower portion 86 so that the male wiping tool 80 can initially pass, in the downward direction, without contacting or with little contact/interference with the tab 34/hole 48, and the contact/interference increases as the male wiping tool 80 moves downwardly to create the downwardly extending deformed material 84 of the tab 34. The base end of the male wiping tool 80 and the female structure 82 can have a gap 88 therebetween that defines the maximum thickness (in the radial direction) of the deformed material 84. The gap 88 can have a size of about 10/1000 in one case or greater than about 5/1000 and/or less than about 15/1000 (in one case greater than about 50% and/or less than about 150% of the thickness of the tab body 52), and thus the deformed material 84 can have a corresponding thickness.

[0040] The male wiping tool 80 may have an upper inner corner/inner radius 87 positioned adjacent to the deformed material 84 during/immediately after wiping operations. The inner corner 87 can have a radius of about 0.0045 (+/1% in one case, or +/3% in another case) (or less than 0.0048 in one case, or less than 0.0050 in another case). The inner radius 87 can be relatively small to provide a gap 85 between the inner radius 87 and the deformed material 84. In this manner the inner radius 87 does not block material from being deformed in what would otherwise be the area of the inner radius 87, to enable material to be deformed into the gap 85 during wiping operations to increase the length of the deformed material 84, and ultimately increase the length of the straight portion 60 and/or lower surface 64.

[0041] The inner upper corner 79 of the female structure 82, about which the deformed material 84 is bent/deformed during wiping operations, and/or the corner 81 of the deformed material 84, can have a radius of 0.0020 (+/1% in one case, or +/5% in another case) (or less 0.0025 in one case, or less than 0.0030 in another case). The inner upper corner 79 can have a relatively small radius to enable the deformed material 84 to be bent relatively sharply downwardly to increase the length thereof, which can ultimately lead to a greater length of the straight portion 60. The diameter of the male wiping tool 80 (forming the deformed material 84 and/or in the vicinity of the deformed material 84 shown in FIGS. 9 and 9A) is about 0.1302 in one case (+/1% in one case, or +/3% in another case) (or greater than 0.1300 in another case). The diameter of the male wiping tool 80 can be desired to be relatively large to provide a greater length to the deformed material 84, which can ultimately lead to a greater length of the straight portion 60.

[0042] After the wiping step of FIG. 9, at least a first coining operation is carried out as shown in FIGS. 10 and 11 using a first coining toolset 90. This coining operation, and other coining steps disclosed herein, can be a stamping operation, and more particularly, can include deforming the workpiece 34/52 by applying sufficiently high forces to induce plastic flow on the surface of the workpiece 34/52 while the workpiece 34/52 is confined in a closed space, in one case defined by a set of dies 92, 94 in a cold forming process. As can be seen first coining toolset 90 can include a male coining tool 92 positioned on one side of the tab 34 (the bottom side, in the illustrated embodiment) and a female structure 94 positioned on the other side of the tab 34 (the top side, in the illustrated embodiment). The male coining tool 92 can have a tapered (narrower) upper portion 96 so that the tab 34 can initially pass, in the downward direction as pressed by the female structure 94, without contacting or with little contact/interference with the tab 34/hole 48. As the female structure 94 continues to press the tab 34 downwardly over the male coining tool 92, the deformed material 84 of FIG. 9 is compressed in the vertical/axial direction, significantly reducing its dimension in the vertical/axial direction, and creating the stiffening area 54, straight portion 60 and/or the flat lower surface 64 (or their precursors).

[0043] The male coining tool 92 has a flat surface 98 aligned in a horizontal/radial plane which defines at least the beginnings of the flat lower surface 64 of the tab 34. The male coining tool 92 also has a straight, axially/vertically aligned surface 100 oriented perpendicular or generally perpendicular to the flat surface 98 which is closely received in the female structure 94 and which defines at least the beginnings of the straight portion 60 of the tab 34. The male coining tool 92 has a upper outer corner/curved portion 102 positioned adjacent to/engaging the tab 34 during coining operations, located between the straight surface 100 and the flat surface 98, which provides at least the beginnings of the curved lower portion 68 of the stiffening area 54. The male coining tool 92 and the female structure 94 also define a gap 104 therebetween that provides a space into which portions of the tab 34 can be deformed to provide at least the beginnings of the curved upper portion 66 of the stiffening area 54.

[0044] The central opening of the female structure 94 can have a diameter (dimension D of FIG. 10) of 0.1305 in one case (+/1% in one case, or +/3% in another case) (or less than 0.1308 in one case, or less than 0.1310 in another case). It may be desired to make the diameter D relatively small to provide additional space, in the radial direction, into which material can be deformed in the first coining step of FIGS. 10 and 11, to enable the stiffening area 54 to have increased length/height, and in particular providing increased length of the lower surface 64 of the stiffening area 54.

[0045] The upper inner corner 91 of first coining toolset 90 and/or the male coining tool 92 (formed at the junction of the female structure 94 and the male coining tool 92), positioned adjacent to the tab 34 during coining operations, can in one case be squared off and not be curved (e.g., have no radius), or have a relatively small/sharp radius (less than 0.0030 in one case, or less than 0.0015 in another case). By providing a sharp corner 91 and/or relatively small radius, any material deformed into the gap 104 tends to be urged radially inwardly (instead of vertically upwardly) to begin vertically aligned with, and thereby contribute to, increased length of the straight portion 60.

[0046] The curved portion or upper outer corner 102 of the male coining tool 92 can have a radius of 0.0030 (+/1% in one case, or +/5% in another case) (or less than 0.0045 in one case, or less than 0.0050 in another case). By providing a relatively small/sharp radius at the curved portion 102, additional deformed material is urged into forming the straight portion 60, providing the same benefits as noted above when describing the benefits of making the lower curved portion/lower radius/second radius 68 relatively small (although, as noted above, the second radius 68 should not be made too small, as is it should still generally match the corresponding radius 70 on the bottom of the rivet 40).

[0047] After the coining step of FIGS. 10 and 11 is completed, as shown in FIG. 12, a second coining step can be carried out, using a second or supplemental coining toolset 112 that in one case includes an upper plate 114 and a lower plate 116, with the tab 34/tab precursor 34 positioned therebetween. The second coining step can reduce the diameter of the hole 48, reduce the height of the deformed material 84/stiffening area 54, reduce the height of the straight portion 60, increase a length of lower surface 64 and/or increase a radius of the upper portion 66 and/or lower portion 68. Since the radius of the lower portion 68 is relatively small in the first coining step of FIGS. 10 and 11 as noted above, the radius can remain relatively small after the second coining step of FIG. 12, even though the radius of the lower portion 68 can be incrementally increased in some cases in the second coining step of FIG. 12. Finally, as shown in FIG. 13, a third coining step can be carried out, similar to the second coining step, and may use the same toolset 112. The third coining step can reduce the diameter of the hole 48, reduce the height of the deformed material 84/stiffening area 54, reduce the height of the straight portion 60, increase a length of lower surface 64 and/or increase a radius of the upper portion 66 and/or lower portion 68.

[0048] As noted above and with reference to FIG. 9A, the corners 79/81 can have a relatively small radius, such that the deformed material 84 is turned downwardly at a relatively sharp angle. This helps to provide an improved configuration of the reinforced area 54, and in particular can provide a longer length of the straight portion 60 (FIG. 7) since more volume of metal is forced down to form the deformed material 84. This also enables more of the deformed material 84 of FIGS. 9 and 9A to be deformed laterally (e.g. to the right in FIGS. 10 and 11, and left/right respectively in FIGS. 12 and 13) to provide the desired shape of the reinforced area 54.

[0049] If the corners 79/81 had a relatively large radius, then less material would be urged into the deformed material 84, and also relatively more material would be remain at an upper area of the tab 34/tab body 52. In this case, for example during the first coining step of FIGS. 10 and 11, there would be excess material on the upper portion of the deformed material 84, which would deformed to the right in FIGS. 10 and 11 into the upper surface of the tab 34/tab body 52. This, in turn, could lead to bulging/wrinkling of material on the upper surface of the tab 34/tab body 52, and/or on the upper surface 47 of the stiffening area 54, which can be avoided by the relatively small corners 79/81. However, it should be noted that the corners 79/81 should not be too small/sharp, which could lead to tearing of the material during the wiping operation of FIG. 9.

[0050] The coining operations can thus in one case be broken out into three incremental steps shown in FIGS. 10-13 to provide the shape of the reinforced area 54 as shown for example in FIG. 7. In particular, attempting to form the shape of the reinforced area 54, from the shape of the deformed material 84 shown in FIG. 9, in a single step may induce unacceptable amounts of stress in the reinforced area 54 and/or lead to breakage of the tab 34/tab body 52 during forming operations. However, in certain conditions it may be possible to form the desired shape of the stiffening area 54 in two coining steps or even one coining step, or on the other hand, if desired, additional coining steps beyond those shown herein can be implemented.

[0051] After the coining operation(s) are complete, the hole 48 can have a diameter of about 130/1000 (+/1/1000 in one case). After these steps are completed the tab 34 can have the various properties and qualities above, particularly relating to the hole 48, stiffening area 54 and associated sizes, dimensions and other properties.

[0052] After the tab 34 and stiffening area 54 is formed, with reference to FIG. 14 the rivet 40 can be passed through the hole 48. The rivet 40 can be coupled to or formed as part of the end cap 10. The rivet 40 is secured in place in the hole 48 via a rivet forming/staking operation using a rivet forming toolset 106, to thereby couple the tab 34 to the end cap 10. The rivet forming toolset 106 can include a male rivet forming tool 108 positioned on one side of the tab 34 and rivet 40 (the bottom side, in the illustrated embodiment) and a three-piece supporting female structure 110 positioned on the other side of the tab 34 and rivet 40 (the top side, in the illustrated embodiment). As the male rivet forming tool 108 is moved upwardly relative to the female structure 110, the rivet 40 is axially compressed and deformed radially outwardly, generally conforming the rivet 40 around the tab 34/hole 48/stiffening area 54, thereby coupling the rivet 40 and the tab 34 as shown for example in FIG. 6.

[0053] As described above, the stiffening area 54 can be positioned on, or protrude downwardly from, a lower side/surface 45 of the tab 34, and not protrude from (or is flush with) an upper side/surface 43 of the tab 34. Positioning the stiffening area 54 on the lower side 45 of the tab 34 helps to reduce or minimize undesired forces to the rivet 40 during coupling of the rivet 40 to the tab 34 (e.g. in the step shown in FIG. 14). In particular, if the stiffening area 54 were to be located on the upper side 43 of the tab 34, the rivet 40 would be forced directly down onto, and be forced to conform around, the upwardly-protruding stiffening area 54, which could cause the rivet 40 to shear and fail. Instead, in the illustrated embodiment the upper surface of the stiffening area 54 is generally flat and planar, and may lack any protuberance(s), which reduces damage to the rivet 40 during rivet formation.

[0054] Having described the invention in detail and by reference to certain embodiments, it will be apparent that modifications and variations thereof are possible without departing from the scope of the invention.