This invention relates to metal containers and the methods for making metal containers.
In the metal container industry, substantially identically shaped beverage containers are produced massively. Dies have been used to neck the tops of the containers.
In some embodiments, a shaped aluminum container has a sidewall comprising a top necked portion and a bottom necked portion. In some embodiments, the thickness of the sidewall in the bottom necked portions varies by at least 0.001 inches. In some embodiments, the thickness of the sidewall in the top necked portions varies by at least 0.001 inches. In other embodiments, the sidewall thickness in either the top or bottom portions, or both vary by at least 0.0015″ or 0.002″. In some embodiments, the sidewall thickness varies by no more than 0.0015″, 0.002″, 0.0025, 0.003″ or 0.004″.
In some embodiments, the shaped aluminum container is manufactured by a process comprising: necking a lower portion of the sidewall with a first necking die so that a working surface of the first necking die contacts a first section of the sidewall and reduces a diameter of the first section of the sidewall by at least 3% in a single die stroke, wherein the thickness of the first section of the sidewall varies along the height of the sidewall by at least 0.001 inches; and necking an upper portion of the sidewall with a second necking die so that a working surface of the second necking die contacts a second section of the sidewall and reduces a diameter of the second section of the sidewall by at least 2% in a single stroke. In some embodiments, the thickness of the second section of the sidewall varies along the height of the sidewall by at least 0.001 inches. In other embodiments, the sidewall thickness in either the top or bottom portions, or both vary by at least 0.0015″ or 0.002″. In some embodiments, the sidewall thickness varies by no more than 0.0015″, 0.002″, 0.003″ or 0.004″. In some embodiments, the lower portion and/or the upper portion is necked with a series of necking dies. A series of necking dies may comprise two or more necking dies. In one embodiment, the lower portion is necked with two necking dies. In one embodiment the first die to neck the lower portion reduces the diameter of the container by about 6% and the second die to neck the lower portion of the container reduces the diameter of the container an additional 4% of the original diameter. In some embodiments, a single necking die may reduce the diameter of the container 2%, 3%, 4%, 5%, 9%, 12% or more.
In some embodiments, the process further comprises expanding the diameter of a middle portion of the sidewall before necking the upper portion of the sidewall. In some embodiments, a thickness of the middle portion varies by at least 0.001 inches. In some embodiments, the thickest portion is at or near the top of the container. In some embodiments, the thinnest or a thin portion can be at or near the top of the container.
In some embodiments, the first and the second necking dies are configured for use on metal bottle stock and comprise a necking surface and a relief. The necking surface comprises a land portion, a neck radius portion, and a shoulder radius portion, each having an inner diameter. The land portion is between the neck radius portion and the relief. The inner diameter of the land is a minimum diameter of the die. The inner diameters of the neck radius portion and the shoulder radius portion are greater than the inner diameter of the land. The relief comprises a relief surface, wherein an inner diameter of the relief surface is at least about 0.01 inches greater than the inner diameter of the land portion and an inner diameter of the relief surface is no greater than a maximum diameter so as to reduce but not eliminate frictional contact between the sidewall and the relief surface while maintaining necking performance when necking the sidewall. In some embodiments, the diameter of the relief surface is about 0.0075 to about 0.035 inches greater than the inner diameter of the land portion. In other embodiments, the diameter of the relief surface is about 0.01, 0.02 or 0.03 inches greater than the inner diameter of the land portion. In some embodiments, the length of the land portion is between about 0.02″ to about 0.08″. In other embodiments, the length of the land is about 0.03″ to about 0.07″. In yet other embodiments, the length of the land portion is between about 0.04″ to about 0.06″. In one embodiment, the length of the land portion is about 0.04″. In some embodiments, the necking die is dimensioned so that when necking the metal bottle stock, the entire land and the relief travel relative to the sidewall in an axial direction and at least a portion of the relief travels beyond a top of the sidewall.
In some embodiments, the land has a surface finish Ra ranging from about 8 μin to about 32 μin. In some embodiments, the relief has a surface finish Ra ranging from about 8 μin to about 32 μin, from about 2 μin to about 6 μin or from about 2 μin to about 32 μin. In some embodiments, the neck radius portion and the shoulder radius portion have a surface finish Ra ranging from about 2 μin to about 6 μin.
In some embodiments, an expansion die for manufacturing metal containers expands the diameter of the middle portion of the sidewall. The expansion die for manufacturing metal containers comprises a working surface and an undercut portion, wherein the working surface is configured to expand a diameter of a metal container having a closed bottom. The work surface comprises a progressively expanding portion and a land portion. The land portion is between the progressively expanding portion and the undercut portion. The outer diameter of the land portion is a maximum diameter of the die. In some embodiments, the length of the land portion is a minimum 0.12″. In some embodiments, the length of the land portion is between about 0.01″ to about 0.12″. In some embodiments, the length of the land portion is between about 0.02″ to about 0.08″. In other embodiments, the length of the land is about 0.03″ to about 0.07″. In yet other embodiments, the length of the land portion is between about 0.04″ to about 0.06″. In one embodiment, the length of the land portion is about 0.04″. The undercut portion comprises an undercut surface having an outer diameter. The outer diameter of the undercut surface is at least approximately 0.01 inches smaller than the outer diameter of the land portion and no less than a minimum diameter so as to reduce but not eliminate frictional contact between the undercut surface and the metal container. The outer diameter of the undercut surface is dimensioned to minimize collapse, fracture, wrinkle and all other physical defects, which may occur during expansion. The work surface is dimensioned so that when inserted into the aluminum container the entire land portion and at least a portion of the undercut portion enter the aluminum container causing the diameter of the middle portion of the sidewall to expand.
In some embodiments, an initial portion of the work surface of the expansion die has a geometry for forming a transition in a container from an original diameter portion to an expanded diameter portion. In some embodiments, the transition is stepped or gradual. In some embodiments, the land portion of the expansion die has dimensions to provide an expanded diameter of a container stock worked by the work surface.
In some embodiments, at least a portion of the work surface of the expansion die has a surface roughness average (Ra) of approximately 8 μin to 32 μin. In some embodiments, at least a portion of the undercut portion has surface roughness average (Ra) of approximately 8 μin to 32 μin. In some embodiments, the outer diameter of the land portion of the expansion die is substantially constant along the length of the land.
In some embodiments, the diameter of the middle portion of the sidewall is expanded with a series of expansion dies.
In some embodiments, the top of the container is dimensioned to accept a closure. In some embodiments, a closure covers an opening on top of the container. In some embodiments, the closure comprises one of: a lug, a crown, a roll-on pilfer proof closure or a threaded closure.
In some embodiments, a can end having a severable pour spout encloses a top of the container.
A process for forming a metal container comprises: providing a container having a sidewall, wherein the sidewall has a thickness and a height, and wherein the thickness varies along the height of the sidewall by at least 0.0010 inches; and necking the container with a necking die so that a working surface of the necking die contacts a section of the sidewall and reduces a diameter of the section of the sidewall by at least 2% in a single stroke, wherein the thickness of the section of the sidewall varies along the height of the sidewall by at least 0.0010 inches before and after necking.
In some embodiments, the necking die used in the process of forming a metal container comprises: a necking surface and a relief; wherein the necking surface comprises a land portion, a neck radius portion, and a shoulder radius portion, each having an inner diameter; wherein the land portion is between the neck radius portion and the relief and the inner diameter of the land is a minimum diameter of the die; wherein the inner diameters of the neck radius portion and the shoulder radius portion are greater than the inner diameter of the land; wherein the relief comprises: (a) a relief surface; (b) an inner diameter of the relief surface is at least about 0.01 inches greater than the inner diameter of the land portion; (c) an inner diameter of the relief surface is no greater than a maximum diameter so as to reduce but not eliminate frictional contact between the metal container and the relief surface while maintaining necking performance when necking the metal container; and wherein the necking die is dimensioned so that when necking the metal container, the entire land and the relief travel relative to the container in an axial direction and at least a portion of the relief travels beyond a top of the container.
In some embodiments, the process of forming a metal container further comprises expanding the diameter of a portion of the sidewall.
In some embodiments, the process of forming a metal container further comprises necking the container with a series of necking dies.
In some embodiments, the process of forming a metal container further comprises expanding the diameter of the portion of the sidewall with a series of expansion dies.
In some embodiments, at least one of the expansion dies comprises: a work surface comprising a progressively expanding portion and a land portion; and an undercut portion; wherein the land portion is between the progressively expanding portion and the undercut portion and an outer diameter of the land portion is a maximum diameter of the die; wherein the undercut portion comprises: (a) an undercut surface; and (b) an outer diameter of the undercut surface, wherein the outer diameter of the undercut surface is: (i) at least approximately 0.01 inches smaller than the outer diameter of the land portion; and (ii) no less than a minimum diameter so as to reduce but not eliminate frictional contact between the undercut surface and the aluminum container; and wherein the work surface is dimensioned so that when inserted into the metal container the entire land portion and at least a portion of the undercut portion enter the metal container causing the diameter of the at least a portion of the sidewall to expand.
In some embodiments, a process for forming a metal container comprises: providing a container having a sidewall, wherein the sidewall has a thickness and a height, and wherein the thickness varies along the height of the sidewall by at least 0.001 inches; and expanding the diameter of the container with an expansion die so that a working surface of the expansion die contacts a section of the sidewall and expands a diameter of the section of the sidewall by at least 2% in a single stroke, wherein the thickness of the section of the sidewall varies along the height of the sidewall by at least 0.001 inches before and after expanding. In some embodiments, the process further comprises necking the container. In some embodiments, the process further comprises expanding the diameter of the container with a series of expansion dies. In some embodiments, the expansion die comprises: a work surface comprising a progressively expanding portion and a land portion; and an undercut portion; wherein the land portion is between the progressively expanding portion and the undercut portion and an outer diameter of the land portion is a maximum diameter of the die; wherein the undercut portion comprises: (a) an undercut surface; and (b) an outer diameter of the undercut surface, wherein the outer diameter of the undercut surface is: (i) at least approximately 0.01 inches smaller than the outer diameter of the land portion; and (ii) no less than a minimum diameter so as to reduce but not eliminate frictional contact between the undercut surface and the aluminum container; and wherein the work surface is dimensioned so that when inserted into the metal container the entire land portion and at least a portion of the undercut portion enter the metal container causing the diameter of the at least a portion of the sidewall to expand.
The following detailed description, given by way of example and not intended to limit the invention solely thereto, will best be appreciated in conjunction with the accompanying drawings, wherein like reference numerals denote like elements and parts, in which:
For the purposes of this specification, terms such as top, bottom, below, above, under, over, etc. are relative to the position of a finished metal container resting on a flat surface, regardless of the orientation of the metal container during manufacturing or forming steps or processes. A finished metal container is a metal container that will not undergo additional forming steps before it is used by an end consumer. In some embodiments, the top of the container has an opening.
The term “bottle stock” is used throughout this specification. However, all of the processes, products and apparatuses disclosed herein are applicable to all metal containers including beverage cans and cups, aerosol cans and food containers. A quotation mark or “in” designates inches.
In some embodiments, a necking die includes a partially textured necking surface 10, which reduces surface contact between the necking surface and the bottle stock being necked in a manner that reduces the force that is required to neck the bottle (hereafter referred to as “necking force”). It has unexpectedly been determined that a necking surface having a textured surface provides less resistance to a bottle stock being necked than a non-textured surface. As opposed to the prior expectation that a smooth, non-textured, highly polished surface would provide less resistance and hence require less necking force, it has been determined that a surface with a relatively low Ra value, i.e. <˜6 micro inches has greater surface contact with the bottle being necked resulting in greater resistance and requiring greater necking force. In some embodiments of the present invention, the increased surface roughness (higher Ra value) reduces the surface contact between the necking surface and the bottle being necked, hence reducing the required necking force.
Reducing the necking force required to neck the bottle stock allows for necking dies having a greater percent reduction than previously available in prior necking dies. It also helps to enable the die to neck through varying thicknesses of metal sidewall.
In one embodiment, a textured surface has a surface roughness average (Ra) ranging from more than or equal to 8 μin to less than or equal to 32 μin, so long as the textured necking surface does not disadvantageously disrupt the aesthetic features of the bottle stock's surface (coating) finish in a significantly observable manner. In one embodiment, a non-textured surface has a surface roughness average (Ra) finish ranging from 2 μin to 6 μin.
Referring to
The textured land portion 13 in
Another aspect of some embodiments of the present invention is a relief 20 positioned in the necking die wall following the necking surface 10. The dimensions of the relief 20 are provided to reduce, but not eliminate, frictional contact with the bottle stock and the necking die, once the bottle stock has been necked through the land 13 and knockout. Therefore, in some embodiments, the relief 20, in conjunction with the partially textured necking surface 10, contributes to the reduction of frictional contact between the necking die wall and the bottle stock being necked, wherein the reduced frictional contact maintains necking performance while reducing the incidence of collapse, buckling, rupturing, wrinkling and other physical defects, and improving stripping of the bottle stock.
In one embodiment, the relief 20 extends into the necking die wall by a dimension X2 of at least 0.005 inches measured from the base 13a of the land 13, in other embodiments, at least 0.010 inches or 0.015 inches. In some embodiments, the relief extends into the die wall no more than 0.025″. The relief 20 may extend along the necking direction (along the y-axis) the entire length of the top portion of the bottle stock that enters the necking die to reduce, but not eliminate, the frictional engagement between the bottle stock and the necking die wall to reduce the incidence of collapse, buckling, rupturing, wrinkling and other physical defects, yet maintain necking performance. In one embodiment, the relief 20 is a textured surface. The transition from the land to the relief is blended, with no sharp corners, so that the metal bottle stock can travel over the land in either direction without being damaged.
In some embodiments of the present invention, a necking system is provided in which at least one of the necking dies of the systems may provide an aggressive reduction in the bottle stock diameter. Although
In one embodiment, the introductory die reduced the diameter of the container being necked by more than 5% in a single necking stroke, or more than 9% in a single necking stroke. The level of reduction that is achievable by the dies of the necking system is partially dependent on the surface finish of the necking surface, necking force, bottle stock material, required neck profile, and sidewall thickness(es). In one embodiment, an introductory necking die provides a reduction of greater than 9%, wherein the initial necking die is configured for producing an aluminum bottle necked package from an aluminum sheet composed of an Aluminum Association 3104 alloy, having an upper sidewall thickness of about 0.0085 inch or less and a post bake yield strength ranging from about 34 to 37 ksi. In some embodiments, the upper sidewall thickness may be 0.0085, 0.0080, 0.0075, 0.0070, 0.0060, 0.0050 inches, just to name a few examples. In some embodiments, the thickness of the sidewall in the bottom necked portions varies by at least 0.0010 inches. In some embodiments, the thickness of the sidewall in the top necked portions varies by at least 0.0010 inches. In other embodiments, the sidewall thickness in either the top or bottom portions, or both vary by at least 0.0015″ or 0.002″ In some embodiments, the sidewall thickness varies by no more than 0.0015″, 0.002″, 0.0025, 0.003″ or 0.004″.
In one embodiment, a necking system is provided in which the plurality of necking dies include an introductory necking die having a reduction greater than 9%, 12 intermediate dies having a reduction ranging from 4.1 to 6.1%, and a final necking die having a reduction of 1.9%.
In one embodiment of the present invention, a method of necking metal containers, utilizing a necking system as described above, is provided including the steps of providing an aluminum blank, such as a disc or a slug; shaping the blank into an aluminum bottle stock; and necking the aluminum bottle stock, wherein necking comprises at least one necking die having an at least partially textured necking surface.
Some embodiments of the present invention provide a necking system including a reduced number of dies and knockouts, therefore advantageously reducing the machine cost associated with tooling for necking operations in bottle manufacturing.
By reducing the number of necking die stages, the present invention advantageously reduces the time associated with necking in bottle manufacturing.
Although the invention has been described generally above, the following examples are provided to further illustrate the present invention and demonstrate some advantages that arise therefrom. It is not intended that the invention be limited to the specific examples disclosed.
Table 1 below shows the reduction provided by a 14 stage die necking schedule, in which the necking die geometry was configured to form an aluminum bottle necked package from an aluminum bottle stock having a upper sidewall sheet thickness of approximately 0.0085 inch and a post bake yield strength ranging from about 34 to 37 Ksi. The aluminum composition is Aluminum Association (AA) 3104. As indicated by Table 1, the bottle stock is necked from an initial diameter of approximately 2.0870″ to a final diameter of 1.025″ without failure, such as wall collapse.
As depicted in Table 1 the necking system includes a first necking die that provides a reduction of approximately 9%, 12 intermediate dies having a reduction ranging from approximately 4.1 to 6.1%, and a final necking die having a reduction of 1.9%.
Referring to
Now turning to the expansion die, a gradual expansion of a container comprised of a hard temper alloy using multiple expansion dies of increasing diameters, as opposed to using one expansion die, allows the diameter of the container to be expanded up to about 40% without fracturing, wrinkling, buckling or otherwise damaging the metal comprising the container. When expanding a container constructed of a softer alloy, it may be possible to expand the container 25% using one expansion die. The number of expansion dies used to expand a container to a desired diameter without significantly damaging the container is dependent on the degree of expansion desired, the material of the container, the hardness of the material of the container, and the sidewall thickness of the container. For example, the higher the degree of expansion desired, the larger the number of expansion dies required. Similarly, if the metal comprising the container has a hard temper, a larger number of expansion dies will be required as compared to expanding a container comprised of a softer metal the same degree. Also, the thinner the sidewall, the greater number of expansion dies will be required. Progressive expansion using a series of expansion dies may provide increases in the container's diameter on the order of 25%, wherein greater expansions have been contemplated, so long as the metal is not significantly damaged during expansion. In some embodiments, the diameter of the container is expanded more than 8%. In other embodiments the diameter of the container is expanded less than 8%, greater than 10%, greater than 15%, greater than 20%, greater than 25%, or greater than 40%. Other percentages of expansion are contemplated and are within the scope of some embodiments of the invention.
Further, when expanding a coated container, a gradual expansion will help to maintain the integrity of the coating. Alternatively, a container may be expanded before coating.
Necking an expanded container formed in accordance with some embodiments of the invention to a diameter greater than or equal to the container's original diameter X does not require the use of a knockout because the container's sidewall is in a state of circumferential tension following expansion. In some embodiments of the invention, a knockout can be used when necking the container.
Referring to
The land portion 200 has dimensions and a geometry for setting the final diameter of the container being formed by that expansion die 500. In one embodiment, the land portion 200 may extend a distance of 0.12″ or more. In other embodiments, the land may extend 0.010″, 0.020″, 0.04″, 0.05, 0.08 or 0.10 or more or less. An undercut portion 350 follows the land portion 200. The transition from the land portion 200 to the undercut portion 350 is blended. The undercut portion 350 extends at least beyond the opening of the container when the die is at the bottom of the expansion stroke to enable the die to maintain control of the metal as it expands and to minimize the container becoming out-of-round.
The work surface 100 may be a non-textured surface or a textured surface. In one embodiment, a non-textured surface has a surface roughness average (Ra) finish ranging from 2 μin to 6 μin. In one embodiment, the work surface 100 may be a textured surface having a surface roughness average (Ra) ranging from more than or equal to 8 μin to less than or equal to 32 μin, so long as the textured work surface 100 does not significantly degrade the product side coating disposed along the container's inner surface.
In some embodiments, immediately following the land portion 200 the surface of the expansion die transitions smoothly to an undercut portion 350 in order to reduce, but not eliminate, the frictional contact between the container 700 and the expansion die 500 as the container is worked through the progressively expanding portion 150 and land portion 200 of the work surface 100. The reduced frictional contact minimizes the incidence of collapse, buckling, rupturing, wrinkling and other physical defects, and improves stripping of the container 700 during the expansion process. In some embodiments, the undercut portion 350 is a textured surface having a surface roughness average (Ra) ranging from more than or equal to 8 μin to less than or equal to 32 μin. In some embodiments, the undercut portion 350 may extend into the expansion die wall by a dimension L of at least 0.005 inches, in other embodiments, at least 0.015 inches or 0.025″. In some embodiments, the undercut portion extends into the die wall no more than 0.025″.
A die system for producing containers is provided including the expansion die 500. The die system includes at least a first expansion die 500 having a work surface 100 configured to increase a container's diameter, and at least one progressive expansion die, wherein each successive die in the series of progressive expansion dies has a work surface configured to provide an increasing degree of expansion in the container's diameter from the previous expansion die. In one embodiment, the die system may also include one or more necking dies.
Although the invention has been described generally above, the following example is provided to further illustrate the present invention and demonstrate some advantages that may arise therefrom. It is not intended that the invention be limited to the specific example disclosed.
In one example, the four expansion dies depicted in
In one embodiment, the containers of
In one example
a show a necking die 196, shown in
The table below shows the dimensions of the container 190 before and after each necking step in necking the lower portion 194 of the sidewall 192.
The dimensions are in inches. The “gap” is the radial distance between the inner diameter of the land 199 of the necking dies 196 and the outer diameter of knockouts 220. The “estimated metal thk” is the maximum thickness of the metal being formed by the necking die. As mentioned earlier, the metal thickness of the sidewall 192 of the containers formed in this example varies by about 0.002″ in the portion of the sidewall 192 being formed, i.e. the necking dies 196 travel over metal that varies in thickness by about 0.002″. The necking dies 196 and the accompanying knockouts 220 are designed to accommodate the thickest metal, as well as the thinnest metal they pass over in the necking process. The thickest metal in the sidewall 192, in this example, is near the top of the container 190. This information also applies to tables appearing later in this specification.
In the table below, “body rad.” and “neck rad.” refer to radii of the expansion dies.
Having described the presently preferred embodiments, it is to be understood that the invention may be otherwise embodied within the scope of the appended claims.
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.
This application is a divisional of U.S. application Ser. No. 13/214,676 filed Aug. 22, 2011 which claims the benefit of priority to U.S. Provisional Patent Application No. 61/375,746 filed on Aug. 20, 2010. The disclosures of the prior applications are considered part of and are incorporated by reference in the disclosure of this application.
Number | Date | Country | |
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61375746 | Aug 2010 | US |
Number | Date | Country | |
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Parent | 13214676 | Aug 2011 | US |
Child | 15620188 | US |