Systems and methods for forming a double dome container

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

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.FIELD OF THE INVENTION

[0002] 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

[0003] 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, stainless 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.

[0004] WO 89 / 07021 A1 is directed to a can bottom forming assembly for forming the bottom wall of a can body. A bodymaker punch urges a can bottom wall first against an outer forming ring, then against a middle forming ring, and then against a domer die. JP H04-253533 A is directed to a method for forming a seamless can bottom wherein a radius portion of a seamless can preform has a cylindrical body and a flat bottom connected to the body via a radius. The inner surface and the outer surface are respectively pressed by a punch having a ring-shaped lower portion and a biased hold-down ring, and at the same time, a bottom outer surface is pressed by a doming die to form an inner wall portion obliquely downward and inward. After forming an annular protruding portion having an inner wall portion connected to the outer wall portion via a ground portion, and a central panel concaved in an arc cross section, the outer wall portion is held between the ring-shaped portion and the hold-down ring, and the ground portion is formed. The center panel, the inner wall portion, and the outer wall portion are relatively moved in the axial direction so as to move away from the nose portion of the ring-shaped portion, thereby reducing the lateral width of the ground portion of the annular protrusion. JP H03-5033 A is directed to a method for forming a bottom of a one-piece molded can, comprising forming a concave center panel. A peripheral portion of the center panel at the bottom has a pressing surface having a shape corresponding to the peripheral portion of the central panel to be formed, and is formed on the peripheral portion by being pressed by at least one pair of pressing members facing each other. Next, while pressing the peripheral portion between the pressing bodies, a portion of the center panel inside the peripheral portion is pressed inwardly into the can with a core die having a spherical pressing surface, and the bottom portion is formed into a spherical shape on the bottom portion. WO 02 / 45882 A1 is directed a method of producing a metal container from a low carbon steel strip or sheet coated on at least one of its surfaces with a coherent laminated coating of a thermoplastic polymer material including one or more redrawing stages which reduce the thickness of the side walls by a drawing / stretching operation, and a partial reverse redrawing stage to produce an initial internal chamber whose depth is produced by a reduction of its height. The initial internal chamber is then redrawn to produce two chambers of differing diameter and depth, the diameter of the initial chamber being decreased by the redraw operation and inserting by base reforming the final chamber with a new internal diameter and depth produced by a reduction in the container height. WO 2013 / 017485 A1 is directed to a method for manufacture of a metal can body in which two or more stretching operations are used so as to reduce the thickness of the central part of a cup base, prior to drawing the cup sidewall and forming a can body. By using two or more stretching operations, it was found possible to control the thickness of the base without significantly reducing pressure performance of the finished can.SUMMARY

[0005] 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.

[0006] A domer assembly for a bottom forming system according to the invention is defined in claim 1 and the claims depending thereon and includes a first domer and a second domer. The first domer includes a first surface that engages a bottom of a metal container during a bottom forming process. The second domer includes a second surface that engages the bottom of the metal container during the bottom forming process. The second domer is movable relative to the first domer.

[0007] A bottom forming system for forming a metal container according to the invention is defined in claim 5 and the claims depending thereon and 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 includes a first dome having a first dome profile and a second dome having a second dome profile.

[0008] A method of forming a bottom of a metal container according to the invention is defined in claim 10 and the claims depending thereon and 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.

[0009] Various implementations described herein may include additional systems, methods, features, and advantages, which cannot necessarily be expressly disclosed herein 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

[0010] 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. FIG. 1 illustrates a bottom forming system with a domer assembly according to embodiments. FIG. 2 is a top view of a first domer of the domer assembly of FIG. 1. FIG. 3 is a top view of the domer assembly of FIG. 1. FIG. 4 is a side view of the domer assembly of FIG. 1 with the domer assembly in a first configuration. FIG. 5 is a side view of the domer assembly of FIG. 1 with the domer assembly in a second configuration. FIG. 6 illustrates the bottom forming system of FIG. 1 during a first stage of a bottom forming process according to embodiments. FIG. 7 illustrates the bottom forming system of FIG. 1 during a second stage of the bottom forming process. FIG. 8 illustrates an example of a bottom of a metal container with a double dome according to embodiments. FIG. 9 illustrates an example of a bottom of a metal container with a double dome according to embodiments. DETAILED DESCRIPTION

[0011] 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 future 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 explicitly 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.

[0012] Described herein are systems and methods for forming a bottom of a metal container. According to the invention, the systems and methods provided herein form a metal container with a double dome. According to the invention, a domer assembly includes a first domer and a second domer 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 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 domer moves 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.

[0013] 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 having a lower metal gauge compared to traditional containers with a dome while still 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 weight (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.

[0014] 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.

[0015] The domer assembly 102 includes at least a first domer 110 and a second domer 112. According to the invention, and as best illustrated in FIG. 2, the first domer 110 is a sleeve having a central aperture 114. In these embodiments, the second domer 112 is an insert for the first domer 110 and is at least partially positioned within the central aperture 114 when the domer assembly 102 is assembled. The first domer 110 is illustrated as surrounding the second domer 112. 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.

[0016] 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 selectively engage the bottom 104 to shape the bottom 104.

[0017] According to the invention, 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 domer 110 in other embodiments. According to the invention, the second domer 112 is positionable within the central aperture 114 of the first domer 110, and the second domer 112 is 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.

[0018] Referring to FIGS. 4 and 5, the domer assembly 102 according to the invention 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 domer 112 may be in a second position relative to the first domer 110 offset from the first position. According to the invention, and as discussed in detail below, the second domer 112 is in the first position during a first stage of the bottom forming process and is in the second position during a second stage of the bottom forming process.

[0019] 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.

[0020] 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 illustrated in 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 FIG. 5, 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 domer 112 need not be moved or offset to the extent shown in FIG. 5.

[0021] 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.

[0022] 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 domer 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.

[0023] Referring to FIG. 6, during a first stage of the bottom forming process, the domer assembly 102 engages 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 domer assembly 102, moving the bottom 104 (e.g., using the punch 108), or a combination thereof. As 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.

[0024] Referring to FIG. 7, during a second stage of the bottom forming process, the second domer 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 (i.e., includes a first dome 126, formed 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 the 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.

[0025] 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 domer assembly used.

[0026] FIG. 8 illustrates a non-limiting example of a bottom 804 of a metal container formed by a 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 4.1605 mm (0.1638 inches) and the second dome depth 832 is 10.922 mm (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 39.370 mm (1.550 inches), and the radius of curvature 836 is 1.270 mm (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.

[0027] FIG. 9 illustrates a non-limiting example of a bottom 904 of a metal container formed by a domer 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 6.223 mm (0.245 inches) and the second dome depth 932 is 11.252 mm (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 the embodiment illustrated, the diameter 934 is 33.020 mm (1.300 inches), and the radius of curvature 936 is 1.270 mm (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.

Claims

1. A domer assembly (102) for a bottom forming system (100), the domer assembly (102) comprising: a first domer (110) comprising a first surface (116) configured to engage a bottom (104) of a metal container during a bottom forming process; and a second domer (112) comprising a second surface (118) configured to engage the bottom (104) of the metal container during the bottom forming process, wherein the second domer (112) is movable relative to the first domer (110), wherein the first domer (110) is a sleeve and the second domer (112) is an insert movable within the sleeve, characterized in that the first domer (110) and the second domer (112) are configured to together form a first dome (126) in a bottom (104) of a metal container during a first stage of a bottom forming process, and that the second domer (112) is configured to form a second dome (128) in the bottom (104) of the metal container during a second stage of the bottom forming process.

2. The domer assembly (102) of claim 1, wherein the second domer (112) is movable within the first domer (110).

3. The domer assembly (102) of claim 1 or 2, wherein the second domer (112) is axially movable relative to the first domer (110).

4. The domer assembly (102) of any one of claims 1-3, wherein the domer assembly (102) is positionable in a first configuration and a second configuration, wherein, in the first configuration, the first surface (116) is continuous with the second surface (118) and together forms a first dome profile, and wherein, in the second configuration, the second surface (118) is offset from the first surface (116) and the second surface (116) forms a second dome profile.

5. A bottom forming system (100) for forming a metal container, the bottom forming system (100) comprising the domer assembly (102) according to claim 1 configured to form a double dome in a bottom (104) of the metal container during a bottom forming process comprising the first dome (126) having a first dome profile and the second dome (128) having a second dome profile.

6. The bottom forming system (100) of claim 5, wherein the second domer (112) is selectively movable relative to the first domer (110).

7. The bottom forming system (100) of claim 5 or 6, wherein the second domer (112) is axially movable relative to the first domer (110).

8. The bottom forming system (100) of any one of claims 5-7, wherein the first domer (110) comprises a first surface (116) and the second domer (112) comprises a second surface (118), wherein the second domer (112) is movable relative to the first domer (110) such that, in a first position of the second domer (112) relative to the first domer (110), the first surface (116) is continuous with the second surface (118), and, in a second position of the second domer (112) relative to the first domer (110), the second surface (118) is offset from the first surface (116).

9. The bottom forming system (100) of any one of claims 5-8, further comprising: a punch (108); and a retainer (106) comprising a receiving area for a metal container, and wherein the domer assembly (102) is movable within the receiving area.

10. A method of forming a bottom (104) of a metal container, the method comprising: forming a first dome profile in the bottom (104) of the metal container using a first domer (110) and a second domer (112) of a domer assembly (102); and forming a second dome profile in the bottom (104) of the metal container by moving the second domer (112) relative to the first domer (110), wherein forming the first dome profile comprises axially moving the first domer (110) and the second domer (112) together in a first direction to engage the bottom (104) of the metal container, and wherein forming the second dome profile comprises moving the second domer (112) relative to the first domer (110) in the first direction, and wherein the first domer (110) is a sleeve and the second domer (112) is an insert within the sleeve, and wherein forming the second dome profile comprises moving the second domer (112) while the second domer (112) is at least partially within the sleeve.

11. The method of claim 10, wherein forming the second dome profile comprises axially moving the second domer (112) relative to the first domer (110).

12. The method of claim 10 or 11, wherein forming the first dome profile comprises using a punch (108) to further form the first dome profile in the bottom (104) of the metal container.

13. The method of any one of claims 10-12, wherein forming the first dome profile comprises engaging a first surface (116) of the first domer (110) and a second surface (118) of the second domer (112) with the bottom (104) of the metal container.

14. The method of claim 13, wherein forming the second dome profile comprises moving the second domer (112) relative to the first domer (110) such that at least a portion of the bottom (104) of the metal container does not contact the first surface (116) or the second surface (118).

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