Patent Application
20070295051
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:
The expansion die 5 of the present invention includes a work surface 10 including a progressively expanding portion 15 and a land portion 20; and an undercut portion 25 positioned following the land portion 20 of the work surface 10. The initial portion 30 of the work surface 10 has a geometry for forming a transition in a container sidewall from an original diameter portion to an expanded diameter portion.
In one embodiment, an expansion die 5 is provided as illustrated in
In another embodiment, an expansion die 5 is provided as illustrated in
The work surface 10 of the expansion die 5 further includes a progressively expanding portion 15 which may include the initial portion 30. The progressively expanding portion 15 has dimensions and a geometry that when inserted into the open end of a can stock works the can stock's sidewall to radially expand the can stock's diameter in a progressive manner as the stock travels along the work surface 10. The degree of expansion may be dependent on the desired final diameter of the container's expanded portion, on the number of expanding dies utilized to form the expanded portion, as well as the material and wall thickness of the container stock. In one embodiment, the work surface 10 may provide the appropriate expansion and forming operations without the need of a knockout or like structure.
The work surface 10 of the expansion die 5 further includes a land portion 20 at the conclusion of the progressively expanding portion 15. The land portion 20 has dimensions and a geometry for setting the final diameter of the expanded portion of the container being formed by that expanding die 5. In one embodiment, the land portion 20 may extend along the necking direction by a distance L1 being less than 0.5″, preferably being on the order of approximately 0.125″. It is noted that the dimensions for the land portion 20 are provided for illustrative purposes only and are not deemed to limit the invention, since other dimensions for the land portion 20 have also been contemplated and are within the scope of the disclosure.
The work surface 10 may be a polished surface or a non-polished surface. In one embodiment, a polished surface has a surface roughness average (Ra) finish ranging from 2μ in to 6μ in. In one embodiment, the work surface 10 may be a non-polished surface having a surface roughness average (Ra) ranging from more than or equal to 8μ in to less than or equal to 32μ in, so long as the non-polished surface 10 does not significantly degrade the product side coating disposed along the container stock's inner surface.
Following the land portion 20 is an undercut portion 25 configured to reduce the frictional contact between the container stock and the expansion die 5, as the container stock has been worked through the progressive expanding portion 15 and land 20 of the working surface 10.
In another aspect of the present invention, a die system for producing shaped beverage containers is provided including the expanding die 5 described in this disclosure. The die system includes at least a first expansion die 5 having a work surface 10 configured to increase a container stock's diameter and to determine the profile at the transition from an original container stock diameter to an expanded portion of the container stock, and at least one progressive expansion die, wherein each successive die in the series of progressive expansion dies has a working surface configured to provide an equal, less than or increasing degree of expansion in the container stock's diameter from the first expansion die. In one embodiment, the die system may also include one or more necking dies. One example of a necking die is depicted in
In another aspect of the present invention, a method of forming a beverage container is provided. The inventive method may utilize the above described expansion die 5 and includes providing a container stock having a first diameter; expanding at least a portion of the container stock to a second diameter greater than the first diameter with at least one expansion die; and forming an end of the container stock to accept a container lid.
The term “providing a container stock”, as used throughout the present disclosure, is meant to denote providing an aluminum blank, such as a disc or a slug, and shaping the blank into an aluminum container stock. At least one expansion die 5, as described above, is then inserted into the open end of the container stock. The number of expansion die 5 may be dependent on the degree of expansion, the material of the container stock and the sidewall thickness of the container stock. In one embodiment, five expansion die's 5 may be utilized to increase the internal diameter of a container stock from about 2.069″ to a diameter greater than the internal diameter of a 211 can, as depicted in
In one embodiment, the method of forming a beverage container may further include necking the container stock to a third diameter after the expanding of the portion of the container to the second diameter and prior to the forming of the end of the container blank to accept the container lid. Examples L and M depicted in
As opposed to prior necking methods, necking an expanded portion of a container that is formed in accordance with the present invention from the expanded portion to a diameter greater than the container stock's original diameter does not require a knockout because the container's sidewalls are in a state of tension following expansion. In some embodiments, of the present invention a knockout may be used when necking the expanded portion of the container stock to a third diameter. Necking from the expanded portion to less than or equal to the container stock's original diameter typically require a knockout. Preferably, a knockout structure is utilized in necking steps wherein the diameter following necking is less than the container stock's original diameter.
In some embodiments of the present invention, the method of forming a beverage container further includes adjusting a travel dimension of the container stock into the necking die 40 and/or the expansion die 5 to provide a minimized transition between successive expanded portions of the container or between expanded portions and necked portions of the container. The travel dimension is defined as the distance the container stock is displaced along the work surface 10 of the expanding die 5 or necking die 40. One example of the effect of adjusting the travel dimension to provide a minimized transition is depicted in Example L of
The method of the present invention may further include shaping with multiple expanding die 5 sets and necking die 40 sets, which may be used in succession to provide multiple alternating expanded portions and necked portions formed into the container sidewall.
Following the final expansion/necking step the open end of the container stock is formed to accept a container lid. The forming step for attaching a container lid to the open end of the container stock may be any known process or method, including forming a flange, curl, thread, lug, attach outsert and hem, or combinations thereof.
The present invention provides an expansion die 5 and method of forming an expanded portion in the sidewall of a beverage container, therefore advantageously reducing the manufacturing cost associated with shaping beverage containers in beverage container manufacturing.
It is noted that the above disclosure is suitable for beverage, aerosol, food or any other container capable of being expanded and/or necked. Additionally, the above disclosure is equally applicable to drawn and iron, drawn, and impact extrusion shaping/expanding methods.
Although the invention has been described generally above, the following example is 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 example disclosed.
A five die expansion system was utilized to expand the diameter of a portion of a container stock having a 0.0088 inch thick sidewall of Aluminum Association (AA) 3104 from an original internal diameter of 2.069″ to a final internal diameter on the order of 2.615″. The expansion represents an increase of approximately 24% in the container stock's diameter without the formation of Lueder's lines or metal tears. The first expansion die providing an expansion of approximately 9%; the second and third expansion die each providing an expansion of approximately 4.5%; and a fourth and fifth expansion die each providing an expansion of approximately 3.0%.
A three die expansion system was utilized to expand the diameter of a portion of the container stock of a 211 can having a 0.0056 inch thick sidewall of Aluminum Association (AA) 3104 from an original internal diameter of 2.603″ to a final internal diameter on the order of 2.860″. In each of the three expansion die the degree of expansion increased by 3% per expansion step.
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.
