CA3233407A1 - Systems and methods for forming a double dome container - Google Patents

Abstract

A bottom forming system for a metal container includes a domer assembly that forms a double dome in a bottom of the metal container during a bottom forming process. The domer assembly includes a first domer and a second domer that is movable relative to the first domer. A method of forming a bottom of a metal container includes forming a first dome profile in the bottom of the metal container using the first domer and the second domer of a domer assembly. The method includes forming a second dome profile in the bottom of the metal container by moving the second domer relative to the first domer.

Description

SYSTEMS AND METHODS FOR FORMING A DOUBLE DOME CONTAINER
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63/250,806, filed September 30, 2021, which is incorporated by reference herein in its entirety.
FIELD OF THE INVENTION
10002] This application relates to systems and methods of forming shaped containers, and, more specifically, to systems and methods for forming; shaped metal containers from metal such as aluminum or aluminum alloys.
BACKGROUND
10003] Many containers such as food and drink cans, fire extinguishers, gas cans, oil filter casings, damper casings, and many other types of articles are made from metal materials such as aluminum, aluminum alloys, stzinless steel, brass, low-carbon steel, and various other suitable materials. The process of forming the container from the metal material :generally includes a number of processes such as a drawing and wall ironing process, a shaping process such as a sequence of full-body necking steps or other mechanical shaping, and other processes as desired to shape a metal blank into a container having a shape as desired. Oftentimes, metal containers that are adapted to hold contents under pressure (e.g., carbonated beverages) are provided with an upwardly extending dome in a bottom wall of the container to resist deformation under pressure.
However, existing dome geometries have a lower limit for a metal gauge of the wall of the container, or, stated differently, domes having a metal gauge below a lower limit will fail and/or deform under pressure.
SUMMARY
100041 Embodiments covered by this patent are defined by the claims below, not this summary.
This summary is a high-level overview of various embodiments and introduces some of the concepts that are further described in the Detailed Description section below.
This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter.
The subject matter should be understood by reference to appropriate portions of the entire specification of this patent, any or all drawings, and each claim.

10005] According to certain embodiments, a domer assembly for a bottom forming system includes a first domer and a second domer. The first domer includes a first surface that may engage a bottom of a metal container during a bottom forming process. The second domer includes a second surface that may engage the bottom of the metal container during the bottom forming process. The second domer is movable relative to the first domer.
[00061 According to some embodiments, a bottom forming system for forming a metal container includes a domer assembly that forms a double dome in a bottom of the metal container during a bottom forming process. The double dome formed in the bottom of the metal container may include a first dome having a first dome profile and a second dome having a second dome profile.
100071 According to various embodiments, a method of forming a bottom of a metal container includes forming a first dome profile in the bottom of the metal container using a first domer and a second domer of a domer assembly. The method includes forming a second dome profile in the bottom of the metal container by moving the second domer relative to the first domer.
100081 Various implementations described herein may include additional systems, methods, features, and advantages, which cannot necessarily be expressly disclosed lieretn but will be apparent to one of ordinary skill in the art upon examination of the following detailed description and accompanying drawings. It is intended that all such systems, methods, features, and advantages be included within the present disclosure and protected by the accompanying claims.
BRIEF DESCRIPTION OF THE DRAWINGS
10009] The specification makes reference to the following appended figures, in which use of like reference numerals in different figures is intended to illustrate like or analogous components.
100101 FIG. l illustrates a bottom forming system with a domer assembly according to embodiments.
1001.1.1 FIG. 2 is a top view of a first domer of the domer assembly of FIG.
I.
1001.2j FIG. 3 is a top view of the domer assembly of FIG. I.
10013] FIG. 4 is a side view of the domer assembly of Fla 1 with the domer assembly in a first configuration.
100141 FIG. 5 is a side view of the domer assembly of FIG. I with the domer assembly in a second configuration.

2 1001.5j FIG. 6 illustrates the bottom forming system of FIG. I during a first stage of a bottom forming process according to embodiments.
100161 FIG. 7 illustrates the bottom forming system of FIG. 1 during a second stage of the bottom forming process.
1001.71 FIG. 8 illustrates an example of a bottom of a metal container with a double dome accordim2 to embodiments.
100181 FIG, 9 illustrates an example of a bottom of a metal container wth a double dome according to embodiments.
DETAILED DESCRIPTION
100191 The subject matter of embodiments is described herein with specificity to meet statutory requirements, but this description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used. in. conjunction with other existing or -Uwe technologies.
This description should not be interpreted as implying any particular order or arrangement among or between various steps or elements except when the order of individual steps or arrangement of elements is explictly described. Directional references such as "up," "down," "top,"
"bottom," "left,"
"right," "front," and "back," among others, are intended to refer to the orientation as illustrated and described in the figure (or figures) to which the components and directions are referencing.
While the systems and methods described herein can be used with any metal, they may be especially useful with aluminum or aluminum alloys.
100201 Described herein are systems and methods for forming a bottom of a metal container. in various embodiments, the systems and methods provided herein may form, a metal container with a double dome. In certain embodiments, a domer assembly includes a first domer and a second dopier that is selectively movable relative to the first domer. During a first stage of a bottom forming process, the first domer and the second domer may together create a dome profile and engage a bottom of a metal container for forming a first dome profile. During a second stage of the bottom forming process, the second denier may move relative to the first domer to further engage the bottom of the metal container, which may change the geometry of the first dome profile and create a second dome profile such that the metal container includes a double dome.
100211 The geometry of the double dome may withstand and improve dome reversal pressure compared to traditional domes, and the double dome may allow for containers to be formed from a metal haying a lower metal gauge compared to traditional containers with a dome while still

3

4 withstanding dome reversal pressure. The ability to use a metal having a lower metal gauge may in turn allow for cans to have a reduced weig.ht (e.g., due to less material), which may provide cost reductions for can makers. In certain aspects, the systems and methods described herein may increase a dome depth/height compared to traditional domes, change the geometry of the dome profile compared to traditional domes, increase work hardening and residual stress, and/or improve the dome reversal pressure for the container. Various other advantages and benefits may be realized with the systems and methods described herein, and the aforementioned benefits should not be considered limiting.
100221 FIGS, 1-7 illustrate a bottom forming system 100 for forming a metal container according to various embodiments. The bottom forming system 100 may be used to at least partially form various metal containers as desired, including but not limited to beverage containers. The bottom forming system 100 generally includes a domer assembly 102 for shaping a bottom 104 for a metal container. The bottom forming system 100 may also include a retainer 106 and. a punch 108, which may assist with the shaping of the bottom 104 during the bottom forming process.
100231 The domer assembly 102 includes at least a first domer 110 and a second domer 112. In sonic embodiments, and as best illustrated in FIG. 2, the first domer 110 optionally may be a sleeve having a central aperture 114. In these embodiments, the second domer 112 may be an insert for the first domer 110 and may be at least partially positioned within the central aperture 114 when the domer assembly 102 is assembled.. While the first domer 110 is illustrated as surrounding the second domer 112, it need not in other embodiments, and the domer assembly 102 may have various other configurations of at least a first domer and a second domer. As a non-limiting example, in some embodiments, the domer assembly 102 may include two domers, each forming a half of the overall domer assembly 102, and that are positioned adjacent to each other.
In this embodiment, the domers may be positioned adjacent to each other but not necessarily positioned within one another and/or one need not be surrounded b3., the other. Other confiurations of domers may be utilized with the domer assembly 102 as desired. In some embodiments, the domer assembly 102 may include more than two domers, such as three domers.
in embodiments with more than two domers, one or more of the domers may be movable relative to a first domer and/or relative to each other.
100241 As best illustrated in FIGS. 2-5, the first domer 110 includes a first surface 116, and the second domer 112 includes a second surface 118. In the embodiment illustrated, the first surface 116 and the second surface 118 have a nonlinear curvature. However, the first surface 116 and the second surface 118 may have various shapes or profiles as desired for forming dome profiles on the bottom of a metal container during the bottom. forming process, As a non-limiting example, in other embodiments, a curvature of the first surface 116 and/or the second surface 118 may be increased or decreased compared to that illustrated in FIGS. 1-7, During the bottom forming process, the first surface 116 and the second surface 118 may selectively engage the bottom 104 to shape the bottom 104.
100251 In vario-us embodiments, the second domer 112 is selectively movable relative to the first domer 110, in certain aspects, the second domer 112 is axially movable relative to the first domer 110, although the second domer 112 may include additional movement relative to the first (limier 110 in other embodiments. In embodiments where the second domer 112 is positionable within the central aperture 114 of the first domer 110, the second domer 112 may be movable within the central aperture 114. Various mechanisms, devices, or features may be utilized such that the second domer 112 is movable relative to the first domer, including but not limited to various mechanical systems, pneumatic systems, hydraulic systems, magnetic systems, combinations thereof, and/or other devices or systems as desired.
100261 Refenring to FIGS. 4 and 5, in certain embodiments, the domer assembly 102 includes at least a first configuration and a second configuration of the first domer 110 and the second domer 112. Movement of the second domer 112 relative to the first domer 110 may adjust the domer assembly 102 to be in the first configuration or the second configuration. In some embodiments, in the first configuration, the second domer 112 may be in a first position relative to the first domer 110, and, in the second configuration, the second dopier 112 may be M a second position relative to the first domer 110 offset from the first position. In various embodiments, and as discussed in detail below, the second domer 112 may be in the first position during a first stage of the bottom forming process and may be in the second position during a second stage of the bottom forming process.
100271 FIG. 4 illustrates the domer assembly 102 in the first configuration where the second domer 112 is in the first position relative to the first domer 110. As illustrated in FIG. 4, in the first position, the second surface 118 may be continuous or flush with the first surface 116 such that the first surface 116 and the second surface 118 together form a first dome profile.
100281 FIG. 5 illustrates the domer assembly 102 in the second configuration where the second domer 112 is in the second position relative to the first domer 110. As diustrated M FIG. 5, in the second position, the second domer 112 is moved relative to the first domer 110 such that the second surface 118 is no longer continuous or flush with the first surface 116, in particular, a side surface 120 of the second domer 112 may optionally extend above the first surface 116. The second surface 118 offset from the first surface 116 forms a second dome profile, in FIGS, the offset position of the second domer 112 relative to the first domer 110 has been exaggerated for clarity of the figure, but during a bottom forming process, the second darner 112 need not be moved or offset to the extent shown in FIG. 5.
100291 As mentioned, in addition to the domer assembly 102, the bottom forming system 100 may optionally include the retainer 106 and the punch 108, In certain embodiments, the retainer 106 includes a receiving area 122, and the domer assembly 102 may be positionable and movable within the receiving area 122 during the bottom forming process. The punch 108 and retainer 106 may be used to further shape the bottom 104 of the metal container during the bottom forming process. However, the particular punch 108 and retainer 106 illustrated should not be considered limiting, and in other embodiments punches and/or retainers with other shapes, profiles, features, etc. may be used as desired. In further embodiments, the bottom forming system 100 may include fewer or additional features as desired.
100301 A bottom forming process using the bottom forming system 100 is described in detail below. Referring to FIG. 1, before bottom forming, the bottom 104 of a metal container may be supported relative to the darner assembly 102, optionally using the retainer 106 and/or the punch 108. In some embodiments, the punch 108 may move the bottom 104 into engagement with the retainer 106 prior to forming with the domer assembly 102.
100311 Referring to FIG. 6, during a first stage of the bottom forming process, the domer assembly 102 may engage the bottom 104 while the domer assembly is in the first configuration.
In certain embodiments, the domer assembly 102 engages the bottom 104 by moving the darner assembly 102, moving the bottom 104 (e.g., using the punch 108), or a combination thereof. A.s illustrated in FIG. 6, the domer assembly 102 in the first configuration forms a first dome in the bottom 104 having the first dome profile. Optionally, in the first stage of the bottom forming process, the punch 108 may advance further towards the retainer 106 to further shape the bottom 104.
100321 Referring to FIG. 7, during a second stage of the bottom forming process, the second darner 112 moves relative to the first domer 110 such that the domer assembly 102 is in the second configuration. Movement of the second domer 112 relative to the first domer 110 lifts up and reshapes the bottom 104 to include a second dome such that the bottom 104 is double domed includes a first dome 126, fumed during the first stage, and a second dome 128, formed during the second stage). Optionally, and as illustrated in FIG. 7, the second domer 112 moving to the second position reshapes the bottom 104 such that at least a portion of the bottom 104 does not contact the first surface 116 or the second surface 118, and a gap 124 may be at least partially formed between the domer assembly 102 and a portion of the bottom 104. In certain aspects, the movement of the second domer 112. against the bottom 104 to lift up the bottom 104 will increase the maximum dome height/depth, change the geometry of the dome profile on the bottom 104, and increase th.e work hardening and residual stress in the bottom 104. In certain aspects, the movement of the second domer 112 in the second stage of the bottom forming process may improve the dome reversal pressure, which may allow for lower gauge metals to be used as the bottom 104 compared to traditional bottom forming processes.
100331 FIGS. 8 and 9 illustrate two non-limiting examples of bottoms of metal containers formed with domer assemblies described herein. The bottoms illustrated in FIG.
8 and 9 are provided, as examples, and other bottoms may have various other profiles as desired depending on the dolma assembly used.
100341 FIG. 8 illustrates a non-limiting example of a bottom 804 of a metal container formed by domer assembly that may be similar to the domer assembly 102 and includes a first domer and a second domer, The bottom 804 includes an end 838 having a first dome 826 and a second dome 828. As illustrated, the first dome 826 has a first dome depth 830 and the second dome 828 has a second dome depth 832. In the embodiment illustrated, the first dome depth 830 is 0.1638 inches and the second dome depth 832 is 0.430 inches. in certain embodiments, the second dome depth 832 is a maximum dome depth of the double dome, In the embodiment illustrated, the second dome 828 also includes a diameter 834 and a radius of curvature 836. In the embodiment illustrated, the diameter 834 is 1.550 inches, and the radius of curvature 836 is 0.050 inches. in other embodiments, the first dome depth 830, the second dome depth 832, the diameter 834, and the radius of curvature 836 may be other values as desired and depending on the domer assembly.
100351 FIG. 9 illustrates a non-limiting example of a bottom 904 of a metal container formed by a /Joiner assembly that may be similar to the domer assembly 102 and includes a first domer and a second domer. The bottom 904 includes an end 938 having a first dome. 926 and a second dome 928. As illustrated, in this example, the first dome 926 has a first dome depth 930 and the second dome 928 has a second dome depth 932. In the embodiment illustrated, the first dome depth 930 is 0.245 inches and the second dome depth 932 is 0..443 inches. In certain embodiments, the second dome depth 932 is a maximum dome depth of the double dome. In the embodiment illustrated, the second dome 928 also includes a diameter 934 and a radius of curvature 936. In th.e embodiment illustrated, the diameter 934 is 1.300 inches, and the radius of curvature 936 is 0.050 inches. In other embodiments, the first dome depth 930, the second dome depth 932, the diameter 934, and the radius of curvature 936 may be other values as desired and depending on the domer assembly.

10036] A collection of exemplary embodiments are provided below, including at least some explicitly enumerated as "illustrations" providing additional description of a variety of example embodiments in accordance with the concepts described herein. These illustrations are not meant to be mutually exclusive, exhaustive, or restrictive; and the disclosure not limited to these example illustrations but rather encompasses all possible modifications and variations within the scope of the issued claims and their equivalents.
100371 Illustration I. A domer assembly for a bottom forming system, the domer assembly comprising: a first domer comprising a first surface configured to engage a bottom of a metal container during a bottom forming process; and a second domer comprising a second surface configured to engage the bottom of the metal container during the bottom forming process, wherein the second domer is movable relative to the first domer.
100381 Illustration 2. The domer assembly of any preceding or subsequent illustrations or combination of illustrations, wherein the second domer is movable within the first domer.
10039] illustration 3. The domer assembly of any preceding or subsequent illustrations or combination of illustrations, wherein the first domer is a sleeve and the second domer is an insert inovablewthM the sleeve.
100401 illustration 4. The domer assembly of any preceding or subsequent illustrations or combination of illustrations, wherein the second domer is axially movable relative to the first domer.
100411 Illustration 5. The domer assembly of any preceding or subsequent illustrations or combination of illustrations, wherein the domer assembly is posMonable in a first configuration and a second configuration, wherein, in the first configuration, the first surface is continuous with the second surface and together forms a first dome profile, and wherein, in the second configuration, the second surface is offset from the first surface and the second surface forms a second dome profile.
10042] Illustration 6. The domer assembly of any preceding or subsequent illustrations or combination of illustrations, wherein the first domer and the second domer are configured to together form a first dome in a bottom of a metal container during a first stage of a bottom forming process, and wherein the second domer is configured to form a second dome in the bottom of the metal container during a second stage of the bottom forming process.
[00431 Illustration 7. A bottom forming system for forming a metal container, the bottom forming system comprising a domer assembly configured to form a double dome in a bottom of the metal container during a bottom forming process comprising a first dome having a first dome profile and a second dome having a second dome profile.
100441 Illustration 8. The bottom forming system of any preceding or subsequent illustrations or combination of illustrations, wherein the domer assembly comprises a first domer and a second domer, wherein the second domer is selectively movable relative to the first domer.
100451 Illustration 9. The bottom forming system of any preceding or subsequent illustrations or combination of illustrations, wherein the domer assembly comprises a first configuration and a second configuration, wherein, in the first configuration, the second domer is at a first position relative to the first domer such that the first domer and the second domer are configured to together form the first dome, and wherein, in the second configuration, the second domer is at a second position relative to the first domer such that the second domer is configured to form the second dome.
100461 Illustration 10. The bottom forming system of any preceding or subsequent illustrations or combination of illustrations, wherein the first domer is a sleeve, and wherein second domer an insert movable within the sleeve.
100471 Illustration 11. The bottom forming system of any preceding or subsequent illustrations or combination of illustrations, wherein the second domer is axially movable relative to the first domer.
100481 Illustration 12. The bottom forming system of any preceding or subsequent illustrations or combination of illustrations, wherein the first domer comprises a first surface and the second domer comprises a second surface, wherein the second domer is movable relative to the first domer such that, in a first position of the second domer relative to the first cleaner, the first surface is continuous with the second surface, and, in a second position of the second domer relative to the first domer, the second surface is offset from the first surface.
10049] Illustration 13. The bottom forming system of any preceding or subsequent illustrations or combination of illustrations, further comprising: a punch; and a retainer comprising a receiving area for a metal container, and wherein the domer assembly is movable within the receiving area.
100501 Illustration 14. A method of thrilling a bottom of a metal container, the method comprising: forming a first dome profile in. the bottom of the metal container using a first domer and a second domer of a domer assembly; and thrming a second dome profile in the bottom of the metal container by moving the second dt-alier relative to the first domer.

100511 Illustration 15. The method of any preceding or subsequent illustrations or combination of illustrations, wherein forming the second dome profile comprises axially moving the second domer relative to the first domer.
100521 Illustration 16. The method of any preceding or subsequent illustrations or combination of illustrations, wherein forming the first dome profile comprises axially moving the first domer and the second domer together in a first direction to engage the bottom of the metal container, and wherein forming the second dome profile comprises moving the second domer relative to the first domer in the first direction.
10053] Illustration 17. The method of any preceding or subsequent illustrations or combination of illustrations, wherein forming the first dome profile comprises using a punch to father form the first dome profile in the bottom of the metal container.
100541 Illustration 18. The method of any preceding or subsequent illustrations or combination of illustrations, wherein the first domer is a sleeve and the second domer is an insert within the sleeve, and wherein forming the second dome profile comprises moving the second domer while the second domer is at least partially within the sleeve.
10055i Illustration 19. The method of any preceding or subsequent illustrations or combination of illustrations, wherein fbrming the first dome profile comprises engaging a first surface of the first domer and a second surface of the second domer with the bottom of the metal container.
[00561 Illustration 20. The method of any preceding or subsequent illustrations or combination of illustrations, wherein forming the second dome profile comprises moving the second domer relative to the first domer such that at least a portion of the bottom of the metal container does not contact the first surface or the second surface.
10057] illustration 21. A metal container comprising a bottom formed by the method of any preceding or subsequent illustrations or combination of illustrations.
10058i Illustration 22. The metal container of any preceding or subsequent illustrations or combination of illustrations, wherein the metal container comprises aluminum or an aluminum alloy.
00591 Illustration 23. The metal container of any preceding or subsequent illustrations or combination of illustrations, wherein the bottom comprises a reduced metal gauge.
100601 The above-described aspects are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the present disclosure. Many variations and modifications may be made to the above-described embodiment(s) without departing substantially from the spirt and principles of the present disclosure. All such modifications and.
variations are intended to be included herein within the scope of the present, disclosure, and all possible claims to individual aspects or combinations of dements or steps are intended to be supported by the present disclosure. Moreover, although specific terms are employed herein, as well as in the claims that follow, they are used only in a generic and descriptive sense, and not for the purposes of limiting the described embodiments, nor the claims that follow.

Claims (23)

PCT/US2022/073494That which is claimed:

1. A domer assembly for a bottom forming system, the domer assembly comprising:
a first domer comprising a first surface configured to engage a bottom of a metal container during a bottom forming process; and a second domer comprising a second surface configured to engage the bottom of the metal container during the bottom forming process, wherein the second domer is movable relative to the first domer.

2. The domer assembly of claim 1, wherein the second domer is movable within the first domer.

3. The domer assembly of claim 1, wherein the first domer is a sleeve and the second domer is an insert movable within the sleeve.

4. The domer assembly of claim 1, wherein the second domer is axially movable relative to the first domer.

5. The domer assembly of claim 1, wherein the domer assembly is positionable in a first configuration and a second configuration, wherein, in the first configuration, the first surface is continuous with the second surface and together forms a first dome profile, and wherein, in the second configuration, the second surface is offset from the first surface and the second surface forms a second dome profile.

6. The domer assembly of claim 1, wherein the first domer and the second domer are configured to together form a first dome in a bottom of a metal container during a first stage of a bottom forming process, and wherein the second domer is configured to form a second dome in the bottom of the metal container during a second stage of the bottom forming process.

7. A bottom forming system for forming a metal container, the bottom forming system comprising a domer assembly configured to form a double dome in a bottom of the metal container during a bottom forming process comprising a first dome having a first dome profile and a second dome having a second dome profile.

8. The bottom forming system of claim 7, wherein the domer assembly comprises a first domer and a second domer, wherein the second domer is selectively movable relative to the first domer.

9. The bottom forming system of claim 8, wherein the domer assembly comprises a first configuration and a second configuration, wherein, in the first configuration, the second domer is at a first position relative to the first domer such that the first domer and the second domer are configured to together form the first dome, and wherein, in the second configuration, the second domer is at a second position relative to the first domer such that the second domer is configured to form the second dome.

10. The bottom forming system of claim 8, wherein the first domer is a sleeve, and wherein the second domer is an insert movable within the sleeve.

11. The bottom forming system of claim 8, wherein the second domer is axially movable relative to the first domer.

12. The bottom forming system of claim 8, wherein the first domer comprises a first surface and the second domer comprises a second surface, wherein the second domer is movable relative to the first domer such that, in a first position of the second domer relative to the first domer, the first surface is continuous with the second surface, and, in a second position of the second domer relative to the first domer, the second surface is offset from the first surface.

13. The bottom forming system of claim 7, further comprising:
a punch; and a retainer comprising a receiving area for a metal container, and wherein the domer assembly is movable within the receiving area.

14. A method of forming a bottom of a metal container, the method comprising:
forming a first dome profile in the bottom of the metal container using a first domer and a second domer of a domer assembly; and forming a second dome profile in the bottom of the metal container by moving the second domer relative to the first domer.

15. The method of claim 14, wherein forming the second dome profile comprises axially moving the second domer relative to the first domer.

16. The method of claim 14, wherein forming the first dome profile comprises axially moving the first domer and the second domer together in a first direction to engage the bottom of the metal container, and wherein forming the second dome profile comprises moving the second domer relative to the first domer in the first direction.

17. The method of claim 14, wherein forming the first dome profile comprises using a punch to further form the first dome profile in the bottom of the metal container.

18. The method of claim 14, wherein the first domer is a sleeve and the second domer is an insert within the sleeve, and wherein forming the second dome profile comprises moving the second domer while the second domer is at least partially within the sleeve.

19. The method of claim 14, wherein forming the first dome profile comprises engaging a first surface of the first domer and a second surface of the second domer with the bottom of the metal container.

20. The method of claim 19, wherein forming the second dome profile comprises moving the second domer relative to the first domer such that at least a portion of the bottom of the metal container does not contact the first surface or the second surface.

21. A metal container comprising a bottom formed by the method of claim 14.

22. The metal container of claim 21, wherein the metal container comprises aluminum or an aluminum alloy.

23. The metal container of claim 21, wherein the bottom comprises a reduced metal gauge.