WO1988005406A1 - Disc removal end wall structure with safety features - Google Patents

Abstract

A full-open, end wall structure (27) comprises a back-scoreline central portion (40, 52) which is ruptured by Class 2 lever action upon lifting of a longitudinally rigid (non-lanced) tab opener (30, 51) as a chisel point (33) at its working end ruptures a minor portion of peripheral scoreline (34). Continued movement of the handle end (37) of tab opener in the direction (46, toward the user) into contact with chime seam (47) provides for continued lever-action rupture of the peripheral scoreline by Class 1 lever action in which the chime seam acts as the fulcrum. Multi-layer folds of sheet metal, providing between layers transition-zone rounded-edge metal (73, 78) for shielding the raw edge of ruptured residual scoreline metal, are prefolded on the removable disc portion and that portion of the end closure structure which remains with the container.

Description

DISC REMOVAL END WALL STRUCTURE WITH SAFETY FEATURES

This application is a continuation-in-part International Application No. PCT/US87/00102 , filed January 1987 and claims the priority of such earlier fil application for all common subject matter. This invention relates to full-open, disc-removal convenience-feature, sheet metal end-closure structure to methods for fabricating and opening such structures and to safety provisions for obstructing access to ra edge metal remaining along a severed scoreline afte opening such a closure structure.

With prior convenience-feature, full-open sheet meta end closures of the disc pull-out type, after initia rupture of a portion of a peripherally-located scoreline it was necessary to pull backwardly on an open-ring in th handle end of the pull-tab opener to continue severance o the remainder of the peripheral scoreline.

Past efforts to facilitate removal of end panel disc by such "pulling-out" methods included special scorelin configuration and disc shapes (e.g. U.S. Patent 3,768,39 of October 30, 1973), and panel profiling techniques (e.g U.S. Patents #3,655,091 of April 11, 1972 and 3,724,709 o April 3, 1973), Also, tab openers for prior art dis pull-out structures were lanced (rather than bein longitudinally rigid) in order to make initial lifting o the handle end easier (e.g. U.S. Patent 4,182,460 of January 8 , 1980) .

In such prior end closure structures, lever-assiste rupture was limited to only a minor portion of th peripheral scoreline during the initial rupturing proce dure. Thereafter, pulling backwardly on the tab opene ring had to be relied on to continue severance of residua metal along the remaining major portion (about 90%) of th peripheral scoreline after such initial lever actio rupture.

Convenience-feature end closures, as previousl available commercially, offered minimal opportunity fo mechanical advantage in removing an end panel; i.e. lever-action assistance for scoreline rupture was used fo only a minor portion of the peripheral scoreline and wa limited to the initiation stage of the removal procedure Such difficulties in opening full-panel end wall struc tures of the prior art subtantially excluded steel en closures from the market. Such difficulties have bee overcome by contributions of the present invention.

The present invention provides for lever-action eas of opening during severance of the peripheral scorelin which defines a full-open disc for removal from the en closure. Also, an elongated, longitudinally-rigid tab-opene structure increases available lever action. A soli configuration handle end, i.e. free of any finger opening can be used and, is preferred in order to help discourag an attempt to pull backwardly on the handle end of th opener from a location which lies internally of a lon gitudinal projection of the container side wall.

Further, the present invention provides a new disc removal procedure and means for establishing use of suc new procedure with the elongated, longitudinally-rigi opener facilitates enabling lever-assistance for periph eral scoreline severance as the handle end of the opene is disposed at a location radially external of th periphery of the end closure.

In addition, new structures and methods ' are combine to enable shielding of residual peripheral scoreline meta in a manner not previously available are made commerciall practicable with flat rolled steel. Previously propose safety-edge measures include U.S. Patents #3,334,775 o August 8, 1967 and 3,986,632 of October 19, 1976. Th present invention provides for folding multi-layers o sheet metal, including flat rolled steel, for shieldin the raw edge of severed scoreline metal, without detrimen to accurate depth scoring of the sheet metal or prematur damage to the residual scoreline metal.

These and other advantages and contributions ar considered in greater detail in describing embodiments o the invention shown in the accompanying drawings; in thes drawings :

FIG. 1 is a plan view of the outer or "public" surface (in relation to a container) of an end closure structure of the invention shown with integral opener in place for opening;

FIG. 2 is a bottom plan view of the inner or "prod¬ uct" surface (in relation to a container) showing the positional interrelationship of back scoreline means with rivet means for securing such opener to the panel to be severed from such closure structure;

FIG. 3 is an enlarged, outer-surface, plan partial view, without the opener in place for better viewing purposes, for describing the back scoreline means, its placement and its contributions to the invention; FIG. 4 is a schematic cross-sectional partial view of an end closure structure of the invention on a container with the integral opener in position prior to initiating scoreline rupture;

FIG. 5 is a schematic cross-sectional partial view of the end closure structure of FIG. 4 subsequent to initia¬ tion of rupture of the back scoreline and a portion of the peripheral scoreline for defining the starter segment of the removable panel;

FIG. 6 is a schematic partial view, sequential to that of FIG. 5, showing completion of an initial rupture phase in which such starter, segment is moved from its original position in the end wall panel of the end closur structure;

FIG. 7 is an outer-surface plan view after continua tion of the arcuate movement of the tab opener to brin such opener into contact with chime seam in a position t continue severance of the peripheral scoreline, beyon that portion partially defining the starter segment, usin the chime seam as the fulcrum enabling subsequent leve action in accordance with the invention; FIG. 8 is an inner-surface plan view of the end wal structure at the opening stage of FIG. 7 with interconnec tion between the tab opener starter segment and remainde of the end wall panel in accordance with _.the inventio providing continued severance of the remainder of th peripheral scoreline by lever action using the chime sea as a fulcrum;

FIG. 9 is a partial schematic view in cross-sectio of structure in accordance with the invention for describ ing the Class I lever action which continues severance o the peripheral scoreline using the chime seam as fulcrum;

FIG. 10 is a schematic cross-sectional view, subse quent to FIG. 9, for showing the "crow-bar" function o the longitudinally-rigid opener using Class I lever actio about the chime seam as the fulcrum in which the severabl panel moves in an axial direction externally away from th container in accordance with the invention;

FIG. 11 is a bottom plan view for showing a preferred back scoreline configuration which further increases the mechanical advantage available with teachings of the present invention and provides other advantages;

FIG. 12 is an outer-surface plan view of the end closure structure of FIG. 11 showing the starter segment resulting from rupture of the back scoreline and a minor portion of the peripheral scoreline in an intermediate opening stage;

FIG. 13 is a top plan view of a preferred specific embodiment of the end closure structure of the invention showing positioning of the opening instructions, as taught herein, to facilitate use of the new disc-removal proced- ure of the invention;

FIG. 14 is a cross-sectional view of the end closure structure of FIG. 13, taken along the line 14-14 of FIG. 13;

FIG. 15 is a perspective view, at the initiation of the opening procedure, of the end closure structure of

FIG. 13 , mounted on a cart body, showing the proper orientation for disc-removal brought by placement of the opening procedure instructions as taught herein;

FIG. 16 is a perspective view, sequential to that of FIG. 15, showing more clearly rupture of the scoreline defined portions of the starter segment as the handle end of the tab opener is moved through an arc of around 90° ;

FIG. 17 is an enlarged perspective partial view sequential to that of FIG. 16, showing the location of th lever fulcrum contiguous to the longitudinal location o the rivet along the length of the opener as the rupture o the peripheral scoreline, beyond the initial phase, take place by force applied to the opener from- a locatio radially exterior of the periphery of the end closure;

FIG. 18 is a perspective view, sequential to that o FIG. 17 showing continued "crow-bar" action disc remova as the arcuate movement of the handle end of the integra opener continues beyond 180 externally of the peripher of the can causing the severable end wall panel to b moved in substantially its original planar form from th container; and

FIG. 19 is a perspective view sequential to that o FIG. 18, showing the final stage of disc removal b lifting on the opener, retained by the disc, from th container; FIGS. 20 through 25 are partial cross-sectiona views, taken radially of the end closure structure, fo describing the sequential steps in accordance with th invention for coordinated formation of shielding for raw edge scoreline metal by folding multi-layers of shee metal, for scoring the sheet metal, for forming a unitar rivet button, for end wall panel profiling and embossing and for riveting a tab opener to be integral with the removable disc, in which:

FIG. 20 shows the results of shaping a cut blank to provide chime seam metal, a chuck wall and sheet metal portions extending in stepped fashion, radially-inwardly in relation to the end closure structure and in an axial direction in relation to a can body for receiving such end closure structure, toward an end wall panel which is recessed axially in relation to such chime seam metal toward the interior of such a container used with such end closure,

FIG. 21 shows start of rivet button formation and an initial stage for subsequent folding of such sheet metal portions in a. sequence subsequent to that of FIG. 20, FIG. 22, which is sequential to FIG. 21, shows forma¬ tion of a smaller diameter rivet button, an intermediate stage in the folding of such sheet me_ntal portions, and start of recessing of a centrally located panel portion,

FIG. 23, which is sequential to FIG. 22, shows peripheral and back scoreline formation, with such scorelines being formed immediately prior to final orientation of either of a pair of multi-layer folds of sheet metal contiguous to the peripheral scoreline on opposite surfaces of such end closure, FIG. 24, which is sequential to FIG. 23, represents the sequence for final rivet button shaping and final orientation of a multi-layer fold of sheet metal fo shielding residual scoreline metal of the removable dis to be separated from the end closure structure and fo embossing the end wall panel with instructions as shown i FIG. 13, and

FIG. 25 shows the rivet button formed into a rive securing a tab opener to the disc and final orientation o the multi-layer fold of sheet metal for shielding th residual scoreline metal of that portion of the en closure structure remaining with the container.

The present invention provides procedure and struc ture which make lever-action and mechanical advantag severance available substantially throughout, or through out the major portion which is significant for ease o opening, of a peripheral scoreline defining a disc to b removed for full-opening of a container.

Endwall closure structure 27, shown in plan view o its outer surface in FIG. 1, is formed with chime sea metal 28 around its outer periphery; a longitudinally rigid tab opener 30 is secured to removable disc 31 b rivet 32. The working end 33 of elongated tab opener 3 is positioned in contiguous relationship to a portion o peripheral scoreline 34; the latter has a circula configuration in such plan view and defines removable dis 31.

Back scoreline leg portions 35, 36 (FIGS. 1 and 2 extend in transverse relationship to the diametric alignment of the longitudinal axis of opener 30. Such legs 35, 36 define, at least in part, a chord across minor portion of the circular peripheral scoreline 34 which helps to define a part of a starter segment which is first moved from its original disposition in the plane o the end wall panel.

The elongated tab opener 30 is non-lanced (no par moves relative to another part) and is fabricated to hav appropriate longitudinal strength characteristics for th functions disclosed herein. For example, sheet metal of suitable gage is selected, and the tab opener is rein forced longitudinally, to enable it to act as a longitud inally rigid, high-strength lever throughout severance o a full panel disc.

Also, a solid configuration for the tab opener 30 free of any ring pull opening at or near its handle en 37, is taught herein to discourage pulling backwardly o the handle after the initial rupturing procedure for th starter segment.

The handle end of the tab opener is located over centrally-located, profiling indentation 38 which is o circular configuration in plan view. Such indente portion of the panel maintains disc 31 substantiall planar and helps to provide finger access for initiatin arcuate movement of the handle end of the tab opener in direction externally away from the container to initiat opening.

The back scoreline configuration of the embodiment o FIG. 1 is shown more completely in the bottom plan view o FIG. 2, in which the end closure structure is seen as i appears on the "inner" surface of the structure which wil confront product held by a container, after assembly. Th back scoreline legs 35, 36 stem from rivet-circumscribin center section 39 of the back scoreline means, in th direction of the adjacent periphery of the end wal closure 27.

Center scoreline section 39 is disposed about th periphery of a portion of rivet 32 (FIG. 3). In th embodiment shown, it is formed from multiple radii so tha a portion 40 protrudes relative to circumferentia portions 41, 42 in a radially inward direction. A smalle radius (in relation to that of 41, 42) provides a semi pointed configuration which ruptures readily to vent th container upon initial lifting of the handle end 37; suc initial rupturing occurs while- tab opener 30 is still in position substantially overlaying scoreline section 39 Arc portions 41, 42 of scoreline section 39 lead to leg 35, 36. Back scoreline legs, such as 35, 36, are directe toward an adjacent portion of the peripheral scoreline 34 Such legs are scored to provide at least. for bending of portion of the sheet metal to form a chord (better seen i later FIGS. 7 and 8) for the subtended arc portion of the circular disc defined by scoreline 34. The included angle confronting the adjacent portion of peripheral scoreline 34 is selected to be no greater than 180 ° . Scored legs 35, 36 help to define starter segment 45 (FIG. 3) which is a minor area of the circular panel 31. A portion of segment 45, between its chord and the chord's subtended arc . is bent inwardly of the container by the opening procedures prior to full panel severance. The scored legs 35, 36 terminate before intersection with the peripheral scoreline; they are part of such chord which, in the embodiment shown, is positioned radially inwardly of center 44 of rivet 32. A resulting bend-line chord in this embodiment acts as an interim fulcrum for Class I lever action of opener 30 during rupture of a portion of the subtended arc of the peripheral scoreline. The area of the segment 45, which is bent toward the interior of a container, is increased by location of legs 35, 36 to form a chord radially inwardly of rivet center 44, over that which would be provided if the chord were oriented to pass through the center of, or radially outwardly beyond the center of rivet 32. Other important configurational aspects of the back scoreline legs are considered in greater detail later herein. Initial rupturing stages of the invention, using the embodiment of FIGS. 1-3, are shown in sequence in FIGS. 4- 6. Arrow 46 indicating the arcuate direction of movemen of the handle end of opener 30; this direction of arcuat movement of the handle end of an opener is utilized in th invention for lever action severance of periphera scoreline throughout the opening procedure. Initially the handle end is started on its arcuate movement b lifting (with a finger, other than the thumb, as show later herein) in a direction toward the user as suc handle end moves initially away from the outer surface o the end wall panel 31.

For nomenclature purposes, note that the periphera chime metal 28 of FIGS. 1 and 2 is formed into chime sea 47 and that the upper surface of metal 28 constitutes th exposed (upper) surface of chime seam 47 as shown in th cross sectional views of FIGS. 4-6. Also note that en wall panel 31 is countersunk in relation to the axia disposition of such upper surface of chime seam 47; an that the centrally located profiling portion 38 i recessed axially from the remainder of end wall panel 31. Rupture of the rivet-circumscribing, portion 39 o the back scoreline and start of rupture of a minor ar portion (partially defining starter segment 45) of th peripheral scoreline 34 are shown in FIG. 5.

After initial rupture, the arcuate movement of th handle end of opener 30 is continued in the same direc tion; the angular direction of the legs of the bac scoreline means toward the adjacent peripheral scoreline helps to determine size of the starter segment. In the embodiment of FIGS. 1-3, the scored legs 35, 36 contribute to defining starter segment 45. After the initial rupturing procedure of FIG. 5, instead of pulling back¬ wardly (as in the prior art) on the tab opener 30, the movement of the handle end of tab opener 30 is continued in the arcuate direction into an upright position as shown in FIG. 6 (and beyond as shown in FIGS. 7, 8 and 9). The chord, determined by the direction of the scored lines of legs 35, 36, acts as the pivot (fulcrum) axis rather than the center 44 of rivet 32 in disposing a portion of starter segment 45 (FIG. 6) inwardly of the container.

Such arcuate movement of the handle end of the opener in the direction 46 continues through an arc in excess of 90° until that surface of tab opener 30, which initially faced as shown in FIG. 1, is brought into contact with the surface of chime seam 47 (FIGS. 7-9). In the embodiment of FIGS. 7-10, the working end 33 of opener 30 acts through a portion of segment 45 on the remainder of disc 31 after the peripheral scoreline portion 48 (FIG. 8) is ruptured. Segment 45 defined by the chord (formed in part by legs 35, 36) and the ruptured portion 48 of the peripheral scoreline is shown as it appears from the inner surface of an end closure structure in FIG. 8.

The contact between the elongated opener 30 and the chime seam 47 (FIGS. 7-10) acts as a fulcrum for continue lever-action severance of the peripheral scoreline 3 (such continued lever-action taking place with the hand o the user being located radially exterior of the peripher of the chime seam and container side wall); the continuin arcuate movement (arrow 46, FIG. 10) of the handle end o opener 30 causes Class I lever action output, at th working end 33 of opener 30 in the direction of arrow 5 of FIG. 10. The lever acts as a "crow-bar" about th chime to move the panel 31 in an outward direction i relation to the container, completing lever-action sever ance of the remainder of the peripheral scoreline 3 around planar configuration disc.

As shown in FIG. 10, the full disc 31 is move upwardly from its countersunk position by such leve action, severing most, if not all, of the remainder of th scoreline 34 (FIG. 3) around disc 31 with the uppe surface of chime seam 47 acting as the fulcrum for suc continued lever action. The tab opener remains secured t the removable disc through segment 45 which remains joine to the remainder of the disc 31 by the residual metal, i any, along legs 35, 36 but, more importantly, by metal beyond the ends of such legs, which comprise safet "shielding" for raw edge severed metal as described late herein.

The disc 31, when severed about its periphery, e.g. as shown in FIG. 10, can be readily lifted away from the open container. The lever action which moves the working end 33 of opener 30 in the direction of arrow 50 severs peripheral scoreline toward that portion of the peripheral scoreline 34 which is diametrically opposite to the initially ruptured portion. As rupture of the peripheral scoreline is converging to complete severance of the disc 31, the force required for removal is diminishing so that the "crow-bar" action requirements are diminishing and, the end wall panel can be lifted from the closure struc¬ ture with any minor remaining peripheral scoreline being severed by such lifting.

An important part of the present concept involves the advantages available in the placement and configura- tion of the back scoreline. In a preferred embodiment shown in FIGS. 11 and 12, the area of the starter segment of the disc is decreased in a manner which significantly increases the mechanical advantage available through tab opener lever action over that available with the con- figuration of FIGS. 1-3. Also, the portion of the end wall panel initially folded inwardly of the container is minimized so as to be insignificant.

A more complete view of the back scoreline con¬ figuration is available in the (product surface) plan view of FIG. 11; and the tab opener 51 is seen on the outer surface view of FIG. 12. Such back scoreline means (FIG. 11) include a rivet-circumscribing central portion 52 and angled legs 53, 54; which, in this embodiment have a curvilinear configuration initially extending transversely to a diameter of the panel and then in a generally radial direction toward adjacent peripheral scoreline 34. The effective included angle between legs 53 , 54 is a minor acute angle; helping to define a minor area (which is significantly less than that of the embodiment of FIG. 3) of the disc to be removed. Scoring for the legs termin- ates at points 55, 56 contiguous to shielding means (on the end wall panel) to be described in more detail later herein. Chord 57, shown in broken lines, ends contiguous¬ ly to termination points 55, 56 at such shielding means. The portion of the periphery scoreline which is ruptured during the initial rupturing procedure is the arc sub¬ tended by chord 57.

Starter segment 58 (FIG. 12), is significantly smaller than segment 45 of the earlier-described FIG. 3 embodiment. As a result, the effective length of the opener acting as work-input lever arm is increased during a portion of the initial rupturing procedure and, also, subsequently due to the increased length of the opener which is disposed radially outwardly of the chime seam for the container, which chime seam acts as the fulcrum for the latter lever action.

The back scoreline means of FIG. 11 is scored for severing about central portion 52 and along the angled legs 53, 54. The angled legs turn toward the adjacent peripheral scoreline with a major component in the same direction as the longitudinal axis of the elongated opener 51. That this configuration can be used without concern for completely ripping a minor wedge (the starter segment) from the removable disc is due to the multi-layer shee metal fold teachings, for shielding raw-edge residual scoreline metal, shown and described in relation to late figures. Such sheet metal shielding folds prevent starte segment 58 (FIG. 12) from being torn completely from th remainder of the disc and enable maximizing the mechanica advantage available through the back scoreline configura tion while maintaining the unitary connection, betwee segment 58 and the remainder of the end wall panel, t continue lever-action severance of the peripheral score line. _

It should be noted that the action of completin severance of the disc takes place while acting on th handle end of tab opener 51 while such handle end i disposed radially externally of the container periphery; and, while outside a projection of the peripherally located scoreline. This provides an added safety featur by eliminating any tendency to grasp the disc bein severed; and, also, eliminates or minimizes spillage o liquid container contents which tended to occur with th prior art "pulling backwardly" opening procedure.

The non-lanced (longitudinally rigid) tab opener 5 partially shown in bottom plan view in FIG. 12 include fold-over rounded-edge metal, such as 59, around its oute periphery (except near its working end) and around th ring-opening. Such longitudinally-extending rounded edg metal increases the longitudinal strength of tab opener 5 for lever action purposes. Profiling of the tab opene such as 60 surrounding rivet 37 (FIG. 13) can also add t that longitudinal strength. Increasing the length an longitudinal strength of the tab opener facilitates th opening procedures taught herein. A chisel point, such a 33 (FIG. 8) provided at the working end of an opener facilitates the initial puncture which starts rupture o the peripheral scoreline.

The specific embodiment of FIG. 13 shows aspects no shown in FIGS. 11, 12, such as protrusions 61 and 62 whic are convex in relation to the outer surface in FIG. 13 Protrusions 61, 62 are used in alignment and stacking and, are located along a line which is intermediate th center of the end wall panel and the center of the rivet on opposite sides of a radial line between such centers in order to serve most effectively for alignment an stacking. Also, linearly-extended, outwardly-projectin profiling bar 65 is positioned at a location below th handle end of the tab opener 51 so as to position such opener horizontally when forming rivet 32; and, also, to help maintain desired access at the working end for opening. The direction of such profiling and alignment protrusion can be seen more clearly in the cross section view of FIG. 14.

An important contribution of the invention involves the predetermined placement of opening instructions 66 (FIG. 13). Referring to FIGS. 15-19, which are used to describe the new disc-removal opening procedure of the invention, the placement and the orientation of such instructions diametrically opposite to the location for the tab opener orients the end closure properly so that the handle end of the opener, upon lifting, can be swung in an arc toward the user. Such direction of arcuate movement is continued (as the arc exceeds 90° ) over the side of the container using the chime seam as a fulcrum to provide leveraged severance of the peripheral scoreline beyond the initial starter segment portion. The index or middle finger is used for initiating disc removal in the new opening method rather than attempting to force the thumb under the handle end of the tab opener as in prior disc removal methods. As seen in FIGS. 13, 15, 16, placement of the instructions 66, requires orienting of the end closure so that the index or middle finger is used in order to be able to read such instructions (unobstructed by the hand of the user). Th thumb, at such stage, is braced against the chime seam 4 and the container side wall.

The handle end of tab opener 51 is lifted by th index and/or middle finger (FIG. 15) in a directio externally away from the container initially. The swin of the handle end as shown in FIG. 16) continues towar the user. In effect the handle end of tab opener 51 i initially lifted away from the end wall panel and is swun in an arc by pulling such handle end toward the user unti tab opener 51 contacts the chime seam; which contact i being initiated in FIG. 16 (slightly after about 90° o arcuate movement) and continues in the sequence shown i

FIGS. 17 and 18. As shown in FIG. 17 the tab opener 51 contacts th chime seam 47, at a location along the length of th opener which is about the same as the location of th rivet 32 along the length of the opener. The starte segment 58 remains unitary with the disc as the periphera scoreline is severed by such lever action.

This arcuate movement of the opener, with the chim acting as the fulcrum for the lever action, is continue as shown in FIG. 18. The end wall panel 31 remain substantially planar, assisted by the profiling of centra portion 38, as the lever action of opener 51 severs th periphery of the panel. The lever-action severance of the peripheral score¬ line, as taught herein, provides smoother opening charac¬ teristics than was possible with any of the prior art full-panel opening techniques. In the prior art there was an abrupt change of direction from the limited lever action, applied only during initial rupture phase, to the "pull backwardly" phase. Frequently the result was spillage of liquid or semi-liquid contents because of such abrupt change in direction of applied force; and, also because of abrupt movements during such backward pulling. In addition to the smooth continuous lever-action sever¬ ance, the opening procedure taught generally results rather naturally in placement of the container on a level surface during opening. Enabling lever-action severance of -the peripheral scoreline substantially eliminates the likelihood of spillage during execution of the opening procedure.

As such leveraged severance in approaching complete¬ ness, the entire end wall panel 31 can be lifted from the closure as shown in FIG. 19. This may occur as severing of the scoreline 34 is converging diametrically opposite to the location of the starter segment 58. The novel features described herein which make fabrication of end closures from flat rolled steel commercially practicable also facilitate opening of end closures made from alumi¬ num. FIGS. 20 through 25 are radial, cross-sectional partial views for purposes of describing sequential stage in the formation, of the end closure structure includin shielding means for the raw edge metal remaining afte severing of the peripheral scoreline.

FIG. 20 shows results of an early forming operatio on a blank involving forming of the chime seam metal an countersinking end wall panel 31 in relation to chim metal 28. Viewed in radial cross-section, chuck wall 6 and a series of "steps and risers" lead to countersun panel 31. Such steps and risers, generally designated 70 are part of the sheet metal portions for forming a pair o multi-layer .folds of sheet metal; one such fold fo shielding residual raw edge metal remaining with^" a dis after severance of the peripherally located scoreline and one for shielding residual raw edge metal on the end wal closure structure remaining with the container.

The step and riser portions of these multi-laye folds of sheet metal are joined to each other and at eac end to the chuck wall and end wall panel, respectively, b transition⁷ zones of compound curvature (i.e. curvilinea in a plane which is perpendicularly transverse to th central axis of the container and, also, rounded in radia cross section). Referring to FIGS. 20, 21 step portion 71 leads to riser portion 72 through intermediate transitio zone 73; step portion 74 is connected to riser portion 72 through curvilinear zone 75; step portion 74 leads to riser portion 76 through transition zone 77; and riser portion 76 leads to transition zone 78 formed with panel 31. In carrying out the procedures of FIGS. 20-25, the timing of the scoring action and the multi-layer folding action, and the extent to which multi-layer prefolding is carried out prior to formation of the peripheral scoreline 34, are important considerations. The peripheral scoreline for the removable disc is to be disposed intermediate and symmetrically in relation to the pair of multi-layer folds which separately shield residual scoreline metal on the separated disc and on the container end structure. The procedure taught enables access by multi-layer pre-fold, on each surface of the end closure, for scoring a single thickness of sheet metal; the latter is supported oppositely on- the remaining surface. The prefolding of the sheet metal layers provides for completing the folding action, around such circular periphery, with only slight movement of rounded transition zone metal being required to enable later shielding without premature damage to residual scoreline metal.

In the operation of FIG. 21 (which is sequential to FIG. 20) an initial rivet button configuration 80, having a broad-diameter shallow-dome shape in cross section is formed. Also, the sheet metal "step" portion 74 i oriented horizontally as shown; peripheral scoring (34 will subsequently take place on such horizontally oriente metal portion 74 to be located radially intermediate th pair of multi-layer folds.

Multi-layer folding of the sheet metal, scorelin formation, rivet button and profiling formation, an riveting a tab opener to the disc are coordinated whil optimizing the number of work strokes. In addition to th above enumerated advantages of scoring a single layer o metal and avoiding premature damage to residual scorelin metal, the rivet button formation and riveting actions ar carried out in sequence without interfering with the meta folding or scoring operations. Completing the fina configurations for the projections 61 and 62, the suppor bar 65 and embossing 66 can be carried out simultaneousl with formation of the rivet button and the profiling t form recessed panel 38.

As carried out in the sequences shown in FIGS. 23-25 metal portions 71 , 72 and compound curvature zone 73 wil form a multi-layer fold for shielding the raw edge meta remaining with the end closure structure on the container Metal portion 74 will be the connector between the pair o multi-layer sheet metal folds; also, the periphera scoreline 34 which will define the removable panel 31, will be carried out on metal portion 74. Metal portio 76, is joined to the horizontal intermediate portion 74 by compound curvature zone 77; compound curvature transition zone 78 and a portion 82 (of the recessed panel adjacent to zone 78) complete the multi-layer fold for providing the shielding for the residual raw edge metal remaining with the severed disc 31.

In FIG. 22, a smaller-diameter, greater-depth rivet button 83 is formed and the pre-folding of the metal portions 76, 82 about zone 78 is increased, as shown. In the illustrated embodiment, multi-layer folds of metal for shielding both the scoreline residual metal on the disc and that remaining with the end structure on the container are provided. Another method (not necessarily part of the prior art) for protecting the residual scoreline metal remaining with the container by profiling of a container side wall has certain disadvantages in diminishing container volume. The embodiment of FIGS. 20- 25 does not diminish container contents and provides an increased area opening for dispensing container contents. In FIG. 23, the folded relationship between sheet metal portions 71, 72 (about compound curvature zone 73 for the . container multi-layer folds) is increased, as shown, while leaving access for scoring tool 86 to form the peripheral scoreline in single-layer metal portion 74. A back scoreline means such as back scoreline 39 (or the back scoreline 52 of FIG. 11) is formed by tool 87, with the support for all scoring being provided by tooling 88.

The sheet metal layers which will remain on th severed disc were prefolded as shown in FIG. 22 whic leaves access for that portion of bucking up (backing) tool 88 (FIG. 23) for scoring; such access past th compound curvilinear zone 78 facilitates accurate dept scoring. As taught herein, variations in flat rolle sheet metal thickness (which are acceptable within normal gage tolerances) do not provide for sufficiently accurate depth scoring when trying to carry out scoring whe working with more than one layer of the metal. Therefore, providing tooling access fo single sheet metal layer scoring after having previously carried out the maximu angled preorientation of metal fold layers while still providing for such access tooling are important contribu¬ tions of the invention.

Note that, notwithstanding prefolding of both separate■multi-layer folds to near-completion, access is provided for the scoring tool on the scoring surface of single layer metal portion 74 and, for back-up tooling on the remaining surface. Providing the prefolded angled relationship shown, enables a minor final orientation for the pair of multi-layer sheet metal folds contiguous to the centerline of the peripheral scoreline. FIG. 24 shows completing the multi-layer folds for the disc and final shaping for rivet button 91; and, FIG. 25 shows riveting the tab opener to the disc using support tooling while completing a very minor movement of the plurality of layers in the fold remaining with the end closure struc¬ ture (into alignment with the centerline of the peripheral scoreline) .

Back scoreline tool 87 (FIG. 23) is selected to establish desired starter segment configuration (central portion and angled legs) for the desired embodiment; back scoreline scoring is carried out during the same work stroke as the peripheral scoring.

As shown in FIG. 24, the plurality of sheet metal layers for shielding the disc are oriented with the rounded-edge zone 78 being oriented in a radially outward direction with a diameter substantially equal to the diameter of the centerline of the peripheral scoreline so as to be in shielding relationship to raw edge metal on the disc after severance by obstructing (i.e. restricting direct) access to such raw edge material.

During the sequence of FIG. 24, a final minor shaping to form rivet bu-tton 91, prior to forming the rivet, takes place and folding of the sheet metal layers for the disc is completed from the prefolded stage shown in FIG. 23. Rounded metal transition-zone 78 around its periphery is then contiguous in plan view to a projection (onto a plane which is transversely perpendicular to the longitudinal central axis of the container) of the centerline of pheripheral scoreline 34. Such shielding means for the raw edge metal of the disc is located on the product side of the end wall panel.

In the final sequence of FIG. 25, tab opener (30, 51) is placed over rivet button 91. Bar 65 helps to support the tab opener horizontally for the rivet forming step carried out between tooling 92, 94. The sheet metal layers comprising the fold remaining on the container can be moved slightly, as shown,- so that compound curvature transition zone 73 having a periphery substantially equal in diameter to that of the centerline of scoreline 34 is disposed, in plan view contiguous to a projection of such center line of scoreline 34, so as to shield the raw-edge of metal which will remain on that portion of the end closure structure remaining with the container when the peripheral scoreline is severed. Metal portions 71, 72 can be folded slightly during this stage to provide such desired shielding by zone 73 while leaving sufficient clearance for removal of end wall panel 31; i.e., zone 73 does not extend radially inwardly beyond the centerline of the peripheral scoreline 34. Such multi-layer fold shielding means remaining with the panel is disposed on the inner surface of the end wall panel. The rounded-edge transition zone (73, 78) of each multi-layer fold at least partially obstructs direct access to its respective raw edge residual metal during and after severance since each such rounded-edge transition zone of its respective multi-^" layer fold is of substantially the same diameter as the contiguous raw edge metal remaining after severance of the residual metal along the centerline of such peripheral scoreline.

The approximate dimensional values presented in the following tables are representative for a 307 (3-7/16") diameter can end structure: sheet metal flat rolled steel coating tinplate or TFS with organic coating nominal thickness .008" - .010" blank diameter 4.225" peripheral scoreline 34 centerline diameter 3.1" residual scoreline metal thickness .002" - .0025" residual metal thickness of scored legs 35, 36 (FIG. 3) .005" residual metal scoreline legs 53, 54 (FIG. 11) .002" - .0025" length of chord 57

(FIG. 11) .75" curvilinear zone 75

(FIG. 21) dia. 3.18" chuck wall 69 dia. 3.25"

(FIG. 21) chuck wall height .18" Axial dimension between center of chime seam metal and panel 31

Fig. 22 .39"

FIG. 25 .21" Rivet head (diameter) .25"

The location of the rivet depends on the dimensional values and location of the tab opener; typically the sharp-edge chisel point of the working end of the tab opener is located contiguous to but sufficiently radially inward of the peripheral scoreline so that the rounded edge 73 of the shielding means remaining with the con¬ tainer does not impede the arcuate movement, initial rupturing action of the working end of the opener. The spacing from the working end of the tab opener to the aperture for the rivet button then determines the location for the rivet button in the end wall panel; typically the center of the rivet would be 1.25", measuring radially, from the center of the end panel in the embodiment of FIG. 11. Typical thicknesses for flat rolled aluminum end closures would be .009" to .012" with residual metal thickness for scored severing lines of about .004" to .005".

Tab openers of the present invention are longitud- inally rigid. They are not lanced or cut out in the vicinity of the rivet as in the prior practice in which

SUBSTI the handle end moved relative to a portion of the opener which was held stationary by the rivet. The longitudinal¬ ly rigid feature enables continuation of the lever action using the chime metal as a fulcrum as described above. The tab opener is preferably free of a finger opening (as in FIG. 1) but can be provided with a ring shaped opener (as in FIG. 12) . Approximate dimensional values for the tab openers identified are set forth below:

Tab Opener 30 (FIG. 1) sheet metal flat rolled steel nominal thickness .012" to .019" type of coating tinplate, TFS or galvanized overall length 1.54" maximum width 1.1" rivet opening - distance from working end .30"

Tab Opener 51 (FIG. 12)

sheet metal flat rolled steel nominal thickness .012" - .019" type of coating tinplate, TFS or galvanized overall length 1.36" maximum width .92 rivet opening - distance from working end .30" The thickness gage for the tab opener can vary with the length and reinforcing provided by edge rolling and metal profiling. The object when working with the starter segment 45 embodiment (FIG. 1) is to provide for fro twelve (12) to fifteen (15) pounds of force to be applie to the handle end of the tab opener without permanen damage to the tab opener due to longitudinal bending o collapsing. With the smaller starter segment provided b the back score line means of FIG. 11, and resultan increased mechanical advantage, force requirements ar decreased by about 60%.

Typically, tab openers fabricated from aluminum woul rely on flat rolled aluminum having a nominal thickness gage between .014" and .022".

The full-open convenience features of the invention rely on means for interrupting and limiting rupture of metal along the back scoreline legs in any embodiments but particularly with a back scoreline of the configuration shown in FIG 11 in which the legs 53, 54 take on a substantially radial direction, which would be likely under ordinary circumstances, to cause starter segment such as 58 to be ripped entirely from the end wall panel 31. The multi-layer sheet metal fold which is radially interior of peripheral scoreline 34 serves an important function (in addition to its later shielding function) during the opening procedure. It acts to limit ripping of starter segment sheet metal along the back scoreline legs and, serves as a hinge-like unitary connection with the remainder of the end wall panel during the continued lever action of the tab opener about the chime seam as a fulcrum. That is, in the back scoreline embodiment of FIGS. 11 and 13, such removal force on the end wall panel is transfered through such plurality of sheet metal layers in such shielding means (see FIG. 17) around the periphery of the disc to be removed. These sheet metal layers also provide a fulcrum axis for the opening procedure between the rivet acting as the fulcrum and the chime seam acting as the fulcrum during which the starter segment is moved from the plane of the end wall panel. Later such sheet metal layers also maintain the opener with the end wall panel through the remainder of the opening procedure and after the disc is removed from the end closure structure.

The back scoreline means configuration facilitates use of a non-lanced tab opener; initial sheet metal rupture is facilitated by the radially inwardly pointed configuration of the central portion of the back score¬ line. For the embossed opening instructions (FIG. 13, 15- 20) to be unobstructed during opening procedures the index or forefinger must be used for initial lifting (FIG. 15) and swinging (FIG. 16) the handle end of the opener toward the user. The follow-through opening procedure (FIGS. 17- 20) resulting from this orientation diminishes the effort, and the spillage risks, of disc removal over what was previously available.

While specific values, materials, and configuration have been shown for purposes of specifically describi embodiments of the invention, other values will available in the light of the above teachings; therefor for purposes of determining the scope of the prese invention reference should be had to the appended claims.

Claims

CLAIMS 1. Full-open, disc-removal convenience-feature shee metal end closure structure, comprising a generally-planar circular-configuration end wal panel circumscribed by unitary chime seam metal fo attaching the end wall closure structure to a cylindrica configuration container, such end wall panel being recessed axially inwardl of such a container in relation to such chime seam metal, a peripherally located scoreline of circular con figuration in plan view of such end wall panel defining removable disc to provide an opening in such end closur structure which facilitates full removal- of containe contents , an elongated, longitudinally-rigid, tab opene secured by a rivet to such removable disc with th longitudinal axis of such elongated tab opening bein oriented diametrically of such end wall panel, such rivet being unitary with the sheet metal of suc removable disc, such tab opener having a working end and a handle en at its longitudinally opposite ends, with such working en being disposed contiguous to a portion of such periphera scoreline for initiating rupture thereof, such rivet being positioned symmetrically on diameter of such end wall panel and being dispose longitudinally toward the working end of such opener alo its longitudinal axis, and back scoreline means positioned in such removabl disc, such back scoreline means including a central portion partially circumscribing suc rivet and located generally radially inwardly wit relation to such rivet toward the center of suc disc, and a leg portion extending from each side of suc central portion toward an adjacent portion of suc peripheral scoreline with the included angle betwee such leg portions being no greater than 180 ° , such leg portions terminating prior to contac with such peripherally located scoreline, such central portion of the back scoreline mean being ruptured by Class II lever action upon initia movement of such tab opener about such unitary rivet as fulcrum during which the handle end of the tab opene moves in an arcuate direction externally away from the en wall panel and such a container, such leg portions of the back scoreline mean extending toward such peripherally located scoreline o opposite sides in relation to such longitudinal axis o the tab opener helping to establish a chord in transvers relationship to such diametrical orientation of such ta 33

52 opener's longitudinal axis, with the location and posi 3 tioning of such chord and such leg portions defining

54 starter segment which is a minor area portion of th

55 removable disc,

56 such starter segment being moved from its origina

57 position in the end wall panel during continuation o

58 opening procedures for such end wall structure after suc

59 Class II initiation of rupture,

60 such starter segment including a portion thereof

61 between such chord and its subtending arc, which is folde

62 inwardly of such a container as such arcuate directio

63 movement of such opener ruptures a minor portion of th 64 peripherally located scoreline which is contiguous to th

65 working end of such tab opener and comprises the subtend

66 ing arc for such chord,

67 with continuing lever-action rupture of such periph 68. erally located scoreline beyond such minor portion bein

69 carried out as a part of continued arcuate directio

70 movement of such handle end of the elongated opene

71 through an arc in excess of ninety degrees which es

72 tablishes contact of such tab opener with such chime sea

73 metal,

74 such chime seam metal contact then acting as

75 fulcrum location for such continued lever action severanc

76 of the peripherally located scoreline in which suc

77 working end of the elongated tab opener acts substantiall 78 in an outwardly-oriented axial direction in relation

79 such a container,

80 such lever action provided by continued arcua

81 direction movement of such elongated tab opener about su

82 chime seam metal as a fulcrum comprising Class I lev

83 action which moves such removable disc in an axi

84 direction externally away from such a container

85 continue rupture of such remainder of the peripherall

86 located scoreline.

1 2. The structure of claim 1 further including

2 raw edge metal shielding means for shielding sever

3 residual metal of the peripherally located scorelin

4 metal, .such shielding means comprising

5 a plurality of layers of end wall panel sheet metal

6 folded in overlying relationship, peripherally circum

7 scribing such removable disc contiguous to such periphera scoreline, such multi-layer sheet metal fold presenting

10 rounded-edge metal portion of ^" circular configuration i 1 plan view of such removable disc having a circumferenc

12 substantially equal to the diameter of the centerline o 3 such peripheral scoreline so as to be in contiguou 4 relationship to such raw edge metal of such periphera 5 scoreline after severance thereof, such rounded-edge meta 6 shielding such raw edge metal by restricting direct acces 7 to such raw edge residual scoreline metal during and afte removal of such disc. 3. The structure of claim 2 further including raw edge shielding means for shielding severed residual metal of the peripherally located scoreline remaining with such end closure structure associated with such a container, comprising a plurality of layers of end wall panel sheet metal, folded in overlaying relationship, located radiall outboard of and contiguous to such circular configuration peripheral scoreline, such multi-layer fold of sheet metal for shieldin raw edge metal remaining with such end closure structur upon removal of such end panel disc presenting, in a ^'pla view of- such end closure structure, a rounded-edg transition zone portion of such multi-layer fold, having circumference substantially equal to that of the cent^'er line of such peripherally located scoreline, which rounde protruding edge is directed radially inwardly of such en wall structure so as to be in contiguous relationship t such raw edge metal about such opened container remainin upon severance of such peripherally located scoreline an removal of such circular disc, so as to shield such ra edge metal by at least partially obstructing direct acces thereto during and after opening. 4. The structure of claim 2 in which such multi layer fold of end wall sheet metal on such removable dis is disposed on the interior surface of such end closure structure in relation to such a container. 5. The structure of claim 3 in which such ulti layer fold of end wall sheet metal remaining with such en closure structure is disposed on the exterior surface o such end closure structure in relation to such a con tainer. 6. The structure of claim 1, further including raw edge metal shielding means for shielding residua scoreline metal subsequent to rupture of such periphera scoreline, such edge shielding means including a pair of multi-layer folds of end wall panel shee metal, one each of such pair of multi-layer folds of shee metal being located on opposite surfaces of such en closure structure in relation to such a container, each of such pair of multi-layer folds of meta presenting a rounded-edge transition zone portion of diameter substantially equal to that of the centerline o such peripheral scoreline for shielding, respectively, th residual raw edge metal about such removable disc an about such end closure structure opening on such a con tainer, by at least partially obstructing direct access t such residual metal raw edges subsequent to severing alon such centerline of the peripherally located scoreline. 7. The structure of claim 6 in which such back scoreline means center portion which partially cir- cumscribes such rivet includes a semi-pointed configuration portion which is non- concentric with such rivet to facilitate rupture by minimizing the portion of the back scoreline which must be ruptured to initiate opening, such non-concentric portion extending radially toward the center of such end wall panel along the diametrical orientation of such elongated opener so as to be ruptured upon such initial movement of such working end of the tab opener to provide venting of such container while such tab opener is still i'n generally overlaying relationship t such central portion of the back scoreline means. 8. The structure of claim 6 in which such leg portions of the back scoreline means exten from such central portion initially in a transvers relationship- to the radially oriented longitudinal axi for such opener, and then extend with a major component o direction which is substantially parallel to such radia direction of such longitudinal axis toward closel adjacent portions.of such peripherally located scoreline. 9. The structure of claim 8 in which such le portions of the back scoreline terminate contiguous t such shielding means of folded layers of unitary shee metal such that such folded layers of sheet metal abou the periphery of such disc to be removed from the end wal structure prevent such starter segment defined by suc back scoreline means from being severed from the remainde of such disc during such opening procedure. 10. The structure of claim 8 in which such longi tudinally rigid tab opener, after being swung through suc arc in excess of 90 ° as part of such initial rupturin procedure, contacts such chime seam at a location alon the longitudinal length of such tab opener which i contiguous to the longitudinal location of such rive along such length of the tab opener. 11. The structure of claim 6 in which such end closure sheet metal comprises flat rolle steel having a nominal thickness of about .008" to abou .010" with residual metal thickness along such periphera and back scoreline means of about .002" to .0025, and such tab opener comprises flat rolled steel having gage between about .012" and about .019". 12. The structure of claim 1 in which such ta opener is longitudinally reinforced and presents a soli configuration handle end which is free of any finge aperture. 13. The structure of claim 1 in which such end closure sheet metal comprises flat rolle aluminum having a thickness gage of about .009" to abou .012" with residual metal thickness along such periphera and back scorel ine means of about .004 " to about .005 " and such tab opener comprises aluminum having a thicknes gage of about .014" to about .022". 14. Method for fabricating an easy-open, disc removal end closure structure for a cylindrical sidewal configuration container from flat-rolled sheet metal so a to provide shielding for residual raw edge metal remainin after severing a circular-configuration periphera scoreline defining such disc for opening such container comprising providing a substantially-planar flat-rolled shee metal blank, such sheet metal blank being symmetricall disposed about a centrally located axis which is perpen dicular to the plane of such blank, forming chime seam metal about the periphery of suc sheet metal blank for attaching such end closure structur to a cylindrical container, and countersinking an end wall panel of such blank, such end wall panel having inner and outer surface in relation to such a container, such surfaces bein substantially planar, such end wall panel, as countersunk, being radiall inward of such chime seam metal and being disposed axiall toward the interior of such a container from such chim seam metal, such end wall panel countersinking step defining a chuck wall of substantially cylindric configuration contiguous to and extending from su chime seam metal in such axial direction toward t interior of such a container, and an intermediate configuration which is steppe in radial cross section in extending between suc chuck wall and the countersunk end wall panel, such stepped configuration including a plurality unitary sheet metal portions in angled relationship each other with a compound curvilinear transition zo located at such chuck wall, between each pair of angle metal portions, and at such end wall panel, establishing an orientation which is substantiall perpendicularly transverse to such central axis for sheet metal portion located intermediate other angle sheet metal portions of the stepped configuration betwee such chuck wall and the countersunk end wall panel, such intermediate sheet metal portion being es tablished for locating a circular-configuration scorelin for defining the periphery of a disc to be removed fro such end closure structure, with such remaining angled sheet metal portions bein located radially inwardly and radially outwardly of suc intermediate sheet metal portion, orienting angled sheet metal portions locate radially on each side of such intermediate sheet metal portion so as to be in acute-angled, overlaying, prefolded relationship to each other to provide for a pair of multi- layer folds of sheet metal, such prefolding orientation of such multi-layer folds of sheet metal being carried out to locate one each of such pair on opposite sides radially of a predetermined location for such circular-configuration peripheral scoreline to be located on such intermediate sheet metal portion and on opposite surfaces of such end wall panel so as to allow access for a scoring tool on one surface and access for a backing-support tool for such scoring on the remaining surface of such intermediate sheet metal portion, then forming such circular-configuration peripheral scoreline to substantially uniform depth in such inter- mediate sheet metal portion, forming a back scoreline means simulaneously wit such peripheral scoreline, such back scoreline mean having a central portion, at least partially circumscrib ing such rivet button and being disposed radially inwardl thereof, and a leg extending from such central portion o each side of such rivet button, in the direction of suc peripheral scoreline with the included angle between th directions for such legs being less than 180 , and- completing disposition of such angularly prefolde 75 sheet metal portions in relation to such periphera

76 scoreline such that the compound-curvilinear transition

77 zone metal forming part of each of such pair of multi

78 layer sheet metal folds has in plan view a diamete

79 substantially equal to that of the centerline of suc

80 peripheral scoreline and is positioned to be aligned i

81 plan view with the centerline of such peripheral scorelin

82 on each such surface of such end wall panel.

1 15. The method of claim 14 in which

2 a rivet button is formed in such countersunk end wal

3 panel during fabrication of such multi-layer folds o

4 sheet metal and an elongated, longitudinally-rigid ta

5 opener is secured to such end wall panel with its workin

6 end contiguous to such peripheral scoreline using suc

7 rivet button which is unitary with such end wall panel by placing such tab opener having a rivet button openin

9 over such rivet button and forming such rivet button int

10 a rivet to make such opener integral with such end wal

11 panel. 16. The method of claim 14 in which such multi-layer folds of sheet metal locate ' radially inwardly of such circular-configuration scorelin are located on the inner surface of such end wall panel, and such scoring is carried ou on the outer surface o such intermediate sheet metal portion while supporting th inner surface thereof. 17. The method of claim 15 in which such elongated tab opener is secured to such end wall panel with the central longitudinal axis of such tab opener being disposed to be coincident with a diameter of such end wall panel, and further including embossing written instructions for opening such container into such end wall panel in symmetrical rela- tiσnship to such diameter along which such tab opener is secured with such embossing being positioned diametrically opposite to the location for such tab opener, and with the lettering in such written instructions being oriented so that the working end of such tab opener is oriented toward the user in order to enable normal reading of such written instructions with the handle end of the tab opener being swung in an arcuate direction toward such user. 18. The method of claim 17 in which such openin instructions are embossed in lines which are concentric with the peripheral scoreline so as to require continuance of such original orientation of the can body and en closure during the opening procedure in order to avoi obstruction of such instructions by the hand of such use as the opening procedure is being carried out. 19. Method for fabricating a convenience-feature en closure structure for a cylindrical container from flat rolled sheet metal so as to facilitate orientation fo full opening of such container and to provide post-openin shielding of residual raw edge metal along a circular configuration peripheral scoreline defining such ful opening, comprising providing a substantially-planar, circular-peripher flat-rolled sheet metal blank of predetermined diameter forming chime seam metal about the periphery of suc sheet metal blank for attaching such end closure structur to a cylindrical container, axially countersinking an end wall panel of suc blank which is cirumscribed by such chime seam metal, such countersinking positioning such end wall pane axially toward the interior of such a container from suc chime seam metal with inner and outer surfaces of such en wall panel being substantially planar, such countersinking defining a chuck wall of substantially cylindrica configuration contiguous to and extending from suc chime seam metal in such axial direction toward th interior of such a container, and a configuration which is stepped in radial cros section with a plurality of angled sheet metal portions interconnected by compound curved transitio zones between such chuck wall and the countersunk end wall panel, establishing a location for a scoreline of circular configuration in plan view of such end wall for defining the periphery of such disc to be removed from such en wall structure, such circular-configuration, peripheral scoreline to be located in uniformly spaced relationship to an radially inwardly of chime seam metal, pre-folding such angled sheet metal portions fo orienting compound curved transition zones contiguous t the location for such circular-configuration scoreline, pre-forming a rivet button in such end wall pane during fabrication of such pre-folded sheet metal por tions, such rivet button being located symmetrically wit relation to a diameter of such end wall panel and dispose in predeterminedly spaced relationship from such periph eral scoreline and disposed toward one longitudinal end o such diameter, forming such circular-configuration, disc-peripher scoreline to substantially uniform depth by scoring single layer of such sheet metal at such pre-establishe location for such scoreline while such sheet metal i being supported at its remaining surface opposite to th surface being scored, completing disposition of such angularly-folded shee metal portions in relation to such scoreline to position rounded edge metal transition-zone forming part of each o such multi-layer folds of metal contiguous to suc scoreline on each such surface of such end wall panel, embossing written opening instructions into such en wall panel symmetrically with such diameter passin through such rivet button, such instructions being locate at the opposite longitudinal end of such diameter i relation to such rivet button and being oriented so tha in order to permit normal reading the rivet button i disposed toward the user, attaching a longitudinally-rigid tab opener to suc end wall panel using such rivet button with the centra longitudinal axis of such tab opener being coincident wit _# such diameter, the working end of such tab opener being contiguou to such peripheral scoreline and being disposed toward th user such that to be able to read such opening instruc tions unobstructed by the user's hand, the index and/o middle finger of the user must be placed under the handl end of such opener to initiate and control opening i accordance with such embossed instructions in which th handle end of the tab - opener is moved in an arcuat direction toward the user.