Patent Grant
10850888
Commercial cans, such as those for holding food, beverages, or products dispensed as an aerosol, can be a “two-piece” or “three-piece” configuration. A conventional two piece can includes a single-piece can body that is formed by a drawing and ironing process also known as drawn and wall ironing (“DWI”). A DWI process draws a metal blank into a cup shape, then the cup is pushed through a series of rings which iron the wall to its desired thickness and length. At the end of the ironing process, the can is pushed into a doming station to form the bottom dome of the integral can body. The open can end is then trimmed, necked down in diameter, deformed outwardly to form a flange.
The second part of a two piece can is the end or lid. Beverage can ends are formed by forming the shell from a flat sheet in a shell press. Then the shell has a tab attached by a rivet in a conversion press.
Modern, lightweight beverage can ends include a curl at its periphery, a wall that extends radially inwardly and downwardly relative to the curl, a reinforcement structure (such as an upwardly opening groove), and a flat or nearly flat center panel. A score in the center panel is configured to open by actuation of the tab.
Beverage can ends for beer often have the requirement of withstanding 90 psi (6.2 bar) internal pressure to survive the pasteurizing process. Beverage cans for carbonated soft drinks often must meet similar standards. The reinforcement structure (that is, the reinforcing groove) between the can end wall and the circular center panel stiffens the structure against the force of internal pressure, and it is at this location that pressurized can ends sometimes fail.
Thus, all commercially successful can ends for carbonated beverages, such as older B64 ends, lightweight ends marketed by Crown Cork & Seal Co., referred to generally as SuperEnd® ends, and those marketed by Ball Corp., referred to generally as CDL™ ends, have an open upwardly opening groove. Alternative reinforcing structures have been proposed, such as a collapsed or restricted structure of an “outwardly extending reinforcing bead” disclosed in Patent Application US2002/0158071 (Chasteen), a “fold having a portion located radially outwardly of the chuck wall” disclosed in U.S. Pat. No. 7,644,833 (Turner), or a “bead which is connected between a radially outer edge of the panel wall and a radially inner edge of the chuck wall structure . . . and extends at least partially radially outwardly” disclosed in WO2013057250 (Dunwoody). But it is conventional for modern beverage can ends to have a reinforcing structure of some type at the periphery of the center panel. For a specific example, the countersink groove of a B64 end includes a relatively steeply inclined outer wall and a relatively upright inboard wall that merges into the center panel. The B64 end has a depth from the top of the panel to the top of the curl of approximately 4 mm. Prior art shell presses for forming conventional beverage can ends are, for example, disclosed in U.S. Pat. Nos. 4,516,420 and 4,549,424 (“Bulso”).
The most common beverage can body (nominal diameter) size is a 211 (2 and 11/16th inches, as the conventional nomenclature in the U.S. is to use the first digit for inches and the second two digits for the number of sixteenths of an inch) or 66 mm diameter. End sizes are typically are 202, 204, or 206 inches, which reflect the most common necking magnitude. Other beverage can nominal diameters are 58 mm and 53.5 mm, which are generally referred to as “Sleek” cans and “Slim Cans,” respectively.
Conventional beverage can end center panels are flat or nearly flat, especially in their unpressurized state, as it is understood that some deformation occurs when the end is under pressure. The term flat encompasses a panel that has recesses, raised beads, and like surface features. The term “nearly flat” also encompasses tolerances and some minor deformation in the shell press and conversion press.
To attach the end to the can, the end curl is placed on the flange of the can body, and then seaming chucks deform the curl and flange to form a conventional double seam. The commercial seaming process for metal containers requires great precision to make reliable containers by the billions without metal wrinkling. Further, insufficient seaming dimensions, such as overlap between the terminal parts of the can flange and the end curl, and like parameters, that can cause failure under pressure. Thus, metal seams have a seaming length, for example, of 2.55 mm (+/−0.15 mm) for a conventional B64 end and 2.50 mm (+/−0.15 mm) for a lightweight end marketed by Crown Cork & Seal, Inc. as its ISE end, and a seam thickness of more than 1.0 mm, and a seaming radius of more than 0.5 mm. Seam thickness is usually calculated or approximated as three times the end thickness plus two times the flange thickness plus a freespace, which is sometimes approximated to be 0.13 mm. Further, the end thickness is greater than the can body flange thickness in the seam in all commercial beverage cans of which the inventors are aware because of end pressure rating requirements.
Three piece cans, which are often employed for holding food, include a cylindrical body with ends seamed onto each end. Conventional food ends typically do not have the same internal pressure rating as carbonated beverage cans. Accordingly, conventional food can ends typically are flat and do not have the strengthening groove.
In a three piece can, a cylindrical body is formed, often by rolling a rectangular sheet and welding a seam. An end is seamed onto each end of the cylindrical body.
Aerosol containers often are three piece cans and include a domed bottom end that is seamed onto the bottom of a cylindrical can body. Aerosol can ends are significantly thicker than ends of beverage cans. Further, aerosol can ends are formed of steel or a relatively ductile aluminium alloy (compared with 5000 series aluminium alloy typical for beverage can ends). Thus, aerosol can ends are usually formed by a press having a domed die center block against which the material is formed, usually by coining, without which the end product has a commercially unacceptable magnitude of wrinkling.
A can end includes a center panel that is concave (that is, viewed from above). The description is directed specifically to a beverage can end of the type capable of use with beer or carbonated soft drink, with specific advantages. The end structure may also be used for food can ends, beverage cans that require a lower pressure rating than is common for carbonated beverages (such as 90 psi), and for products dispensed from aerosols.
The embodiment having a dome panel without a countersink has the advantages of reduced weight of the shell, which in turn enables a more compact seam that also provides weight savings while forming a commercially acceptable seam. Moreover, necking the can body to accommodate the end, as well as the end structure itself, produces an advantageous headspace clearance (that is, the distance between the underside of the end or the pour opening and the liquid surface). The end structure provides improved cleanliness as there is no groove to trap debris during transit (for example) and liquid from the can drain away from the periphery and possibly back into the open can rather than becoming trapped in the groove. And as the pour opening can be located closer to the seam (because there is no groove between the pour opening and the seam), the drinking experience can be more like drinking from a glass compared with conventional cans.
In this regard, an unseamed can end capable of withstanding 90 psi internal pressure after seaming onto a can body is formed of an aluminum alloy, preferably a 5000 series alloy (although other allows, such as a 3000 series aluminum alloy) is contemplated. The unseamed can end includes: (i) a curl structure adapted for being seamed together with a flange of a can body; (ii) a chuck wall extending radially inwardly from the curl structure, the chuck wall is adapted for contact with a chuck during the seaming process; (iii) an inwardly domed panel radially inwardly from the chuck wall; (iv) a score formed on the panel; and a tab (preferably curved at approximately the same shape as the panel) or other opening feature attached to the panel and adapted for rupturing the score in response to actuation of the tab by a user to form a pour opening. The other opening features can include a press button, a peelable foil, and the like. The panel extends from a lower end of the chuck wall into the panel with no countersink bead therebetween. The can end preferably is a beverage can end, but the structure may also be employed for a food can end or an aerosol product end.
Preferably, the diameter of the can end is less than 10 times a height of the dome at a center of the end, and more preferably between 4 and 8 times a height of the dome at a center of the end. The end formed as described herein can be made lightweight, such as of a 5000 series alloy that is less than 0.20 mm thick, more preferably less than 0.18 mm thick, an in preferred embodiments less than 0.16 mm thick.
The curl of the end is configured such that the unseamed end has a stacking height S of between 1.7 and 3.0 mm, and preferably at least 1.8 mm. The curl is configured to have a width of less than 3.5 mm, more preferably less than 3.0. mm, measured radially and horizontally between the outboard most point of the curl structure and the point on the curl at which a seaming panel of the curl structure yields to a relatively straight portion of a chuck wall of the end.
The panel is a dome-shaped such that the slope of the tangent of a curve defined by the end at every point of the chuck wall and the domed panel is non-zero except at the center. The panel dome in cross section is formed by multiple radii that decrease with radial position from the panel center. For example, the panel dome radius R1 inboard and proximate the chuck wall is between 0.5 mm and 2 mm, the dome radius R4 at the center of the panel is between 35 mm and 55 mm, and the can end diameter is between 38 and 52 mm. Preferably radius R1 is between 0.5 mm and 4 mm, the radius R2 is between 7 mm and 20 mm, the radius R3 is between 28 mm and 41 mm, the radius R4 is between 35 mm and 55 mm, all for a can end diameter is between 38 and 52 mm. More preferably, R1, R2, R3, and R4 are between 0.7 mm and 2.0 mm, 10 mm to 16 mm, 31 mm to 37 mm, and 40 mm and 50 mm, and more preferably approximately 1.0 mm, 13 mm, 34 mm, and 44 mm for a 42 mm end.
Aspects of the end pour opening and tab include a pour opening defined by the score has a straight line dimension measured radially by a line that is inclined at an angle defined by opposite points of the pour opening of between 14 mm and 19 mm, more preferably between 15 mm and 17 mm. The horizontal clearance defined between the innermost part of the chuck wall and the outboard-most portion of the score is between 0.6 mm and 3.0 mm, preferably between 1.0 mm and 2.0 mm, and more preferably between 1.0 mm and 1.4 mm.
The finger clearance F defined between the innermost part of the chuck wall and distal-most portion of the tab heel measured on an incline is between 6 mm and 15 mm, more preferably between 7 mm and 10 mm.
The dome depth, measured from the top of the curl to the top of the panel at the center (but if the rivet is at the center then from a projection of the curve of the dome at the center) is preferably between 5 mm and 16 mm, more preferably between 6 mm and 10 mm, and in some embodiments shown approximately 8 mm. The dome depth can be chosen according to principles consistent with optimizing end performance along with desired diameters parameters.
Another embodiment that employs aspects of the present invention is a full aperture end. The full aperture end has a shell like the easy-opening end summarized above and formed by the processes summarized below, and has a score extends around a perimeter of the panel proximate the wall. A full aperture end may in some circumstances be made smaller than other styles, such as is approximately a 30 mm size, which the inventors surmise is a size that enables a smaller ring-type FAE tab with clearance for seaming.
According to another aspect of the invention, the unseamed end is seamed onto a can body. The unseamed can end and can body combination comprises: a drawn and ironed can body including a base, a sidewall, and a flange; and an unseamed can end. The unseamed can end includes a curl structure engaged with the flange; a chuck wall extending radially inwardly from the curl structure, the chuck wall is adapted for contact with a chuck during the seaming process; an inwardly domed panel radially inwardly from the chuck wall; a score formed on the panel; and a tab attached to the panel and adapted for rupturing the score in response to actuation of the tab by a user to form a pour opening.
The radial clearance between the flange proximate a neck of the can and the curl is at least 0.5 mm. The clearance may be measured at a chuck wall of the end. Consistent with the lightweight nature of the can end, the thickness of the can end measured at the curl structure is less than 10% or 20% thinner than the thickness of the flange. In part to accommodate a smaller curl, yet provide sufficient material for forming an adequate seam, the flange width less than 1.8 mm, preferably less than 1.6 mm, and more preferably less 1.5 mm, measured radially from an inboard side a vertical portion of a neck of the can to an outermost lip of the flange. And the curl height is greater than the width of the flange, such as by at least 0.5 mm, more preferably by at least 0.2 mm (or at all). The curl clearance dimension measured horizontally between an outermost tip of the flange and an innermost tip of the curl is between 0.4 to 1.2 mm.
The panel dimensions and configuration, tab and score, and other features for the combination end and can body are as described above with respect to the unseamed can end.
According to another aspect of the present invention, a container may employ inventive aspects of the seam consistent with the advantages of the end shell structure. In this regard, a container for holding a product comprises: a drawn and ironed can body including a base, a sidewall, and a neck; and a can end. The can end includes: a chuck wall extending radially inwardly from the curl structure, the chuck wall is adapted for contact with a chuck during the seaming process. The terminal portion of the can body and a terminal portion of the end being joined together by a double seam having a seam height that is less than approximately 2.2 mm and preferably is approximately 2.0 mm. The end may have an inwardly domed panel radially inwardly from the chuck wall; a score formed on the panel; and a tab attached to the panel and adapted for rupturing the score in response to actuation of the tab by a user to form a pour opening. Alternatively, the container may be a bottom end for an aerosol product.
The container preferably has thickness of a terminal portion of the end that is no more than a thickness of the terminal portion of the can body, and a seam thickness that is no more than 1.1 mm, more preferably no more than 0.96 mm, and preferably between 0.85 and 0.93 mm. Consistent with the thin end shell, the seam radius preferably is no more than 0.6 mm, more preferably no more than 0.55 mm.
The double seam on the container includes: (i) a cover hook, an end hook, a seaming panel, and a chuck wall of the terminal portion of the can body and (ii) a body wall and a body hook of the can end; an overlap between body hook and the cover hook preferably is between 0.65 and 1.2 mm, more preferably approximately 0.9 mm. The panel dimensions and configuration, tab and score, and other features of the end and can body are as described above with respect to the unseamed can end and the combination unseamed can end and can body flange.
For an example of a container that employs an inventive seam, the container includes a can body and a can end that includes: a chuck wall extending radially inwardly from the curl structure, the chuck wall is adapted for contact with a chuck during the seaming process; an inwardly domed panel radially inwardly from the chuck wall; a terminal portion of the can body and a terminal portion of the end being joined together by a double seam having a seam height that is less than approximately 2.2 mm. For this end, a score and tab are optional. The end preferably is formed of an aluminum alloy that is less than 0.20 mm thick, more preferably less than 0.18 mm thick, and in preferred embodiments less than 0.16 mm thick. This container may hold a comestible product or a product dispensed by a propellant.
According to another aspect of the present invention, a method of forming a can end shell capable of withstanding 85 psi after seaming to a can body, includes the steps of:
In this regard, and throughout the specification, the terms “upper” and “lower”, and related forms of the words, refer to positions relative to the finished end—such that upper refers to a position relative to or a direction toward the outer portion of the end, and lower refers to a position relative to or direction toward with the inner side of the end, when the end is on the can—rather than position in the tooling. Thus, the tooling components and method steps defined herein apply to the end regardless of its orientation in the tooling.
The pressure sleeve assembly of the engaging step (c) includes an outer pressure sleeve and an inner pressure sleeve, and in the engaging step (c) the inner pressure sleeve contacts an underside of the blank in response to relative movement by the punch, and the outer pressure sleeve contacts an underside of the blank after the inner pressure sleeve contacts the blank. The inner pressure sleeve has a contact surface having a shape that matches the shape of an opposing local portion the dome-shaped punch, and the outer pressure sleeve having a contact surface that matches the shape of an opposing portion of the dome-shaped punch.
The inner pressure sleeve and outer pressure sleeve are independently depressible such that during a first phase of the engaging step (c) the inner pressure sleeve is depressed by the relative downward movement of the punch while the outer pressure sleeve stays relatively stationary and spaced apart from the blank and during a second phase of the engaging step (c) each one of the inner pressure sleeve and outer pressure sleeve contact the underside of the blank and each one of the inner pressure sleeve and the outer pressure sleeve are depressed by the relative downward movement of the punch. The term “depressed” as used herein refers to compressed from its rest position. Preferably, springs are employed but other means are contemplated.
Preferably, the clamping step (a) includes forming a pre curl near the periphery of the blank by forced applied between the upper sleeve and the lower sleeve. The clamping step (a) may include forming a slight curl near the periphery of the blank by forced applied between the upper sleeve and the lower sleeve.
Preferably, the method includes a step of curling the periphery of the blank that is output from the shell press processes to form a finished curl capable of being seamed onto a can body flange. The curling step preferably is a two step process, each process performed in its own tooling.
A shell press for forming a can end shell capable of withstanding 85 psi after seaming to a can body, the shell press includes: a central dome-shaped punch; a pressure sleeve assembly located opposite a portion of the dome-shaped punch, the pressure sleeve having a contact surface that matches a corresponding opposite portion of the dome-shaped punch, the pressure sleeve being adapted for movement in response to movement of the dome-shaped punch such that the pressure sleeve contact surface and the corresponding opposite portion of the dome-shaped punch are adapted to deform a metal blank into a dome in response to downward movement of the dome-shaped punch; an upper sleeve concentrically located outboard of the dome-shaped punch, the upper sleeve having a concave contact surface; a lower sleeve concentrically located outboard of the pressure sleeve, the lower sleeve having a convex contact surface; the lower sleeve contact surface and the upper sleeve contact surface are adapted for curling a portion of a periphery of the blank; a punch sleeve concentrically located outboard of the upper sleeve; and a pressure pad concentrically located outboard of the lower sleeve.
The pressure sleeve assembly includes an outer pressure sleeve and an inner pressure sleeve. The inner pressure sleeve is concentrically located inboard of the outer pressure sleeve, and the inner pressure sleeve has a contact surface that matches a corresponding opposite portion of the dome-shaped punch. The outer pressure sleeve has a contact surface that matches a corresponding opposite portion of the dome-shaped punch. Each one of the inner pressure sleeve and the outer pressure sleeve is downwardly moveable in response to downward movement of the dome-shaped punch, such that the inner pressure sleeve and the outer pressure sleeve being independently moveable downwardly.
The inner pressure sleeve and the outer pressure sleeves are configured such that the inner pressure sleeve contacts a deformed portion of the blank before the outer pressure contacts a deformed portion of the blank. The tooling also includes a blanking tool concentrically located outboard of at pressure pad, wherein the punch sleeve and the lower pressure pad are adapted for vertical movement relative to the blanking tool to cut the blank from a metal sheet.
The structure and function of the unseamed and seamed can ends is included by reference in this summary of the method and tooling. The method and tooling have the goal and feature of forming the end shell without significant, which as used herein refers to a degree of wrinkling consistent with how the term is used by persons familiar with end shell structure, function, and seaming, and is meant to refer to a commercially acceptable product upon mass production. The method and tooling are particularly adapted to thin shells formed of aluminum alloys that are less ductile than steel ends used in aerosol packaging.
The method and tooling may be employed without regard to the material or end use, and thus encompasses aluminum, steel or other metal blanks, an end products for food, beverage, or aerosol containers, unless expressly stated in the claims. Moreover, all aspects of the structure and function of the products described herein apply to the description of the tooling and methods, and all aspects of the tooling and methods described herein apply to the structure and function of the products, to the extent that consistency and logic permits.
Referring to the figures, a container package, such as package 5, includes a beverage can end 10 and a can body 50. End 10 in its unseamed configuration, as shown for example in
A tear panel is formed by a score 18, which after actuation by tab a 30 forms a pour opening. Score 18 may be formed by conventional methods and tooling, but as applied to curved panel 16, as will be understood by persons familiar with can end technology in view of the present disclosure. Tab 30 is attached to panel 16 by a rivet 20 (preferably conventional) at a rivet island. Tab 30 is curved at approximately the same curvature as panel 16 in the embodiment shown. Tab 30 includes a nose 32 for contacting the tear panel during the opening process and an opposing 36 heel for grasping by a user to actuate the tab.
As illustrated in
The 42 mm can size is illustrated in
Panel 16 of unseamed end 10 defines a dome depth D of preferably between 6 mm and 12 mm, more preferably between 6 mm and 10 mm, and in the embodiment shown in the figures, 8 mm. Additional information is provided in Table 1. Dome depth D, as illustrated in
Can body 50 in the embodiment shown in
A neck 56, which has a reduced diameter relative to sidewall 54, extends from an upper end of sidewall 54. It is understood that the magnitude of necking for package 5 may in some embodiments be greater than conventional 12 ounce beverage cans, as is known in the art. In the unseamed state, neck 54 terminates in a flange 62, as illustrated in
Seam 60, which preferably is a double seam, joins end 10 and body 50. In the seamed state, all or most of curl 12 forms seam 60 and all of most of wall 14 forms the inboard surface of seam 60, as described more fully below. Preferably, as illustrated in
As illustrated in
Referring particularly to
The dome 16 profile preferably comprises a series of progressively increasing radii from a small radius next to the chuck wall to a large central radius. The progressively increasing dome radii can minimise the depth of the curve, thus optimising material usage and providing a shallow dome depth. The shallow dome depth may in some configurations make it easier or feasible for the end to be manufactured using conventional metal forming processes without wrinkling during the drawing operation that might occur with very thin material.
For the example of a 42 mm end size, the preferred radius values for R1 through R4 (that is, from the outboard-most radius to the center radius) are 1, 13, 34 and 44 mm, as illustrated in
Can ends having the above ranges of radii are for the preferred embodiment of a 42 mm end size. The can end may also have a diameter between 38 mm and 52 mm, or 40 mm and 46 mm. Moreover, the general shape of the end structure disclosed herein, including the ratio of end diameter to height and seam dimensions, may be used with much larger ends, such as up to and including 82 mm diameter ends currently used for 1 liter beer cans. The present invention is not limited to the particular radii ranges or number of ranges unless stated in the claims. Rather, it is understood that the dome may elliptical or formed by a series of splines, or other shape.
Table 1 below provides values of some parameters for the 42 mm, 46 mm, and 50 mm ends, which values are the products of finite element analysis design and optimization. The “constrained” values control some parameters, such as freeboard height H of the package and dome height D. The “free” values are the optimized parameters without external constraints applied to the solution, and thus better reflect the benefits of the improvement of the end technology disclosed and claimed herein.
Shell thickness is the starting gauge in millimeters of 5000 series aluminium alloy. Cut edge diameter is the blank diameter in millimeters. Mass is the mass of the shell reflecting the cut edge diameter. Dome height is dimension D explained herein. Reversal pressure is the calculated pressure in PSI that the dome profile reverses. The weight savings is a percentage metal weight savings compared with a 50 mm end marketed by Crown Cork & Seal, Inc. as its “ISE” end, which is well known in the field. Shell diameter is the diameter in millimeters, such as indicated in
The preferred minimum length T-a for tab 36a is 27 mm to enable a rivet and a finger to be insertable into ring 36a. Thus, end 10a, 10a′ can be made as small as about 30 mm, which dimension provides clearance around tab 36a for seaming tooling.
Can body 50 is as described for first embodiment container package 5. And the dome profile of panel 16a is as described for first embodiment container package 5. As rivet 20a is within score 18a, actuation of tab 30a and rupture of score 18a fully around the perimeter of panel 16a enables the tear panel to be fully removed from the remainder of the container package 5a. Such configuration is referred to a full aperture end.
Referring to
Wall 14′, as shown for example in
According to an aspect of the present invention, the structure of end 10 enables thinner material to be employed, which in turn enables a smaller seam than conventional beverage can double seams to be employed. In this regard, the inventors are not aware of any commercial aluminum package having a double seam formed by an end material that is thinner than or has a similar thickness to the can flange material. In particular, the domed end thickness is no more than 20% greater than the curl thickness, preferably less than 10% thicker than the curl. The benefit of this compact geometry is that the end seam radius is small and this locks the seam in place during pressurization, thus preventing seam unravelling As the material is very thin it is more susceptible to unravelling thus the locking effect is critical for the buckle performance.
Preferably, curl thickness is 0.16 mm, which is significantly less that any of the curl thicknesses of any conventional ends.
Further, seam length L, measured from the uppermost point of the seam to the lowermost point on the seam along the seam centerline, is preferably below 2.2 mm, and in the preferred embodiment is approximately 2.0 mm. Seam thickness ST, measured at widest point of the outboard surfaces of wall 14′ and seaming wall 66 perpendicular to the longitudinal axis of the seam, preferably is no more than 1.1 mm, more preferably no more than 0.96 mm, and in the embodiment shown dimension ST is approximately 0.85 to 0.93 mm. The end seam radius ESR, measured at the top of the seam and reflected either by the seaming panel radius SPR or the seaming wall radius SWR preferably is no more than 0.6 mm, more preferably no more than 0.55 mm, and even more preferably no more than 0.5 mm. Further, an overlap dimension OL between body hook 76 and the cover hook 70 is between 0.65 and 1.2 mm, and preferably approximately 0.9 mm.
Referring again to
Aspects of the smaller seam dimensions and end thicknesses (compared with prior art), and the like, are reflected in the unseamed configuration of end 10 and can flange 62. Flange width FW is large enough to form an adequate overlap dimension OL for acceptable seaming. Flange width FW is measured radially from an inboard side a vertical portion of neck 56 to an outermost lip 63 of the flange and preferably is no more than 1.8 mm, more preferably, no more than 1.6 mm, and preferably about 1.5 mm. A curl width dimension, measured radially and horizontally between the outboard most point of the curl structure and the point on the curl at which a seaming panel of the curl structure yields to a relatively straight portion of a chuck wall of the end, preferably is less than 3.5 mm, more preferably less than 3.0 mm, and in the embodiment shown 2.8 mm. For ease of measurement, the curl width CW can be measured from the outermost point on the curl radially (that is, horizontally when viewed in cross section) to a point P on the inboard surface of the end at curl 12 or wall 14.
Curl height CH preferably is greater than flange width FW, which the inventors believe is contrary to conventional dimensional relationships in commercial beverage cans. Preferably, height CH is greater than flange width FW by at least 0.2 mm, and more preferably by at least 0.5 mm. In the embodiment shown, curl height is 2.1 mm. A curl clearance dimension CC measured horizontally between an outermost tip of the flange and an innermost tip of the curl is between 0.4 to 1.2 mm, and preferably is approximately 0.5 mm.
As best shown in
As illustrated in
Tool pack 110 includes a dome-shaped punch 120, a pair of pressure sleeves 130 and 140, an upper sleeve 150, a die center ring 160, a punch sleeve 170, a pressure pad 180, a cut edge 190, and a stripper hold down tool 200. Punch 120 has a dome-shaped surface 122 that approximately matches the profile of panel 16, accounting for some spring back. The calculated profile of shell 8 is illustrated in
Upper sleeve 150 is aligned with the die center ring 160 and is concentric with punch 120. Die center ring 160 is concentric with outer pressure sleeve 140. Punch sleeve 170 is aligned with pressure pad 180 and is concentric with upper sleeve 150. Pressure pad 180 is concentric with lower sleeve 160.
Inner pressure sleeve 130 and outer pressure sleeve 140, with an opening at the center, provide a compressive force that help to diminish wrinkling during drawing the end. The spring forces of 136 and 146 may be chosen for this purpose, but preferably are not large enough to “coin” the blank, which occurs in the prior art dome formation described in the background section. Inner pressure sleeve 130 is configured to move up and down independently from outer pressure sleeve 140.
Alternatively, the inventors surmise that a single pressure sleeve 130a shown in
Curling tooling 210A of the first curling process includes an upper pressure ring 220a, an opposing lower pressure ring 230a, and an upper curling tool 240. The shell 8, which is the product of the shell press 100, is illustrated in
Ends formed in the configurations described herein can have the advantages (compared with ends formed with a flat center panel and/or countersink groove) of a reduced blank size and/or reduced thickness, which could enable a reduction in the metal usage of the end. In addition to the information above, the inventors predict that a 42 mm shell may use only about half the material weight (approximately 1.05 g) as a corresponding lightweight end, such as that marketed by Crown Cork & Seal as a 202 size 202 Superend® can end. Further, because the end 10 shown in the figures does not have a groove near the wall, the pour opening can be configured closer to the seam, which in some circumstances may improve the drinking and/or pouring process. The end also is well suited to normal pressure ratings, such as the ability to withstand 90 psi internal pressure.
As an example, a seamed embodiment of package 5 may include end 10′ as described herein seamed together with DWI beverage can 50 of a 66 mm size or 211 size can body. The package also encompasses 58 mm size or 204 size and 53 mm size or 202 size can body and other sizes referred to herein. The present invention is not limited by can body diameter unless expressly set out in the claim, as the disclosure of can body sizes is to support specific claims to standard can body sizes, including 211 cans as well as those sometimes referred to as sleek or slim cans.
The present invention is not limited to the particular embodiments or combination of features disclosed herein. For one example, without intending to be limiting, the dome profiles may be chosen according to particular desired parameters. The design principles may also be used for containers that do not require 90 psi ratings, such as low carbonation soft drinks or food containers, such that the end material may be thinner or smaller diameter than described above.
This claims the benefit of U.S. Provisional Application Ser. No. 62/301,128 filed Feb. 29, 2016, the disclosure of which is hereby incorporated by reference as if set forth in its entirety herein.
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