Apparatus and method for forming a cup with a reformed bottom

Abstract

An apparatus and method of forming a metallic cup that is subsequently reformed into a container body. More specifically, an apparatus and methods used to form a metallic cup with a reformed bottom having an inwardly oriented projection are disclosed. The inwardly oriented projection reduces a height of the metallic cup but utilizes the same amount of metallic stock material as a taller cup with substantially the same diameter that does not have an inward projection. The inwardly oriented projection thus allows the use of a conventional bodymaker and other can manufacturing tools to convert the cup into a container body of a preferred size and shape.

Claims

1. An apparatus for forming a reformed metallic cup having a bottom portion with an inwardly oriented projection from a metallic cup with a substantially flat bottom portion, the improvement comprising: providing the metallic cup with the substantially flat bottom portion and a sidewall; a die center punch to support an interior surface of the substantially flat bottom portion of the metallic cup proximate to at least the sidewall, the die center punch having a cavity with a depth at least equal to a height of the inwardly oriented projection; a reform draw pad with a substantially centered cavity; and a reform punch opposing the die center punch to apply a force to an exterior surface of the substantially flat bottom portion of the metallic cup opposite of the die center punch, said reform punch comprising an extension which travels through the substantially centered cavity of the reform draw pad and into the cavity of said die center punch to form the inwardly oriented projection, wherein a height of the inwardly oriented projection is at least about 5 percent of a height of a sidewall of the reformed metallic cup, and wherein the reform draw pad is configured to move from a first position in which the extension of said reform punch does not extend into the substantially centered cavity of the reform draw pad to a second position in which the reform punch extension extends through the substantially centered cavity of the reform draw pad, wherein the sidewall of the metallic cup with the substantially flat bottom portion is supported by an interior surface of a redraw die as the inwardly oriented projection is formed, and wherein the height of the sidewall of the reformed metallic cup with the inwardly oriented projection is between about 60 percent and about 97 percent of a height of the sidewall of the metallic cup with the substantially flat bottom portion.

2. The apparatus of claim 1, wherein the cavity of the die center punch has a diameter of between about 1.5 inches and about 3.0 inches.

3. The apparatus of claim 1, wherein the extension of the reform punch has a generally cylindrical shape with a rounded upper edge portion and an endwall that is generally planar.

4. The apparatus of claim 1, wherein an interior diameter of the cavity of the die center punch is at least equal to an interior diameter of the substantially centered cavity of the reform draw pad.

5. The apparatus of claim 1, wherein the reformed metallic cup is subsequently formed into a container body by a container bodymaker.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the invention and together with the Summary of the Invention given above and the Detailed Description of the drawings given below serve to explain the principles of these embodiments. In certain instances, details that are not necessary for an understanding of the disclosure or that render other details difficult to perceive may have been omitted. It should be understood, of course, that the invention is not necessarily limited to the particular embodiments illustrated herein. Additionally, it should be understood that the drawings are not necessarily to scale.

(2) FIGS. 1A-1E depict a prior art method and apparatus used to form a metallic cup;

(3) FIGS. 2A-2F depict a method and apparatus for forming a cup with an inwardly oriented projection in a closed endwall portion with a draw-redraw apparatus according to one embodiment of the present invention as well as a cup with an inward projected formed by the apparatus; and

(4) FIGS. 3A-3F depict a method and apparatus for forming a cup with an inwardly oriented projection in a closed endwall portion with a draw-redraw apparatus according to another embodiment of the present invention as well as a cup with an inward projected formed by the apparatus.

(5) Similar components and/or features may have the same reference number. Components of the same type may be distinguished by a letter following the reference number. If only the reference number is used, the description is applicable to any one of the similar components having the same reference number.

(6) To assist in the understanding of one embodiment of the present invention the following list of components and associated numbering found in the drawings is provided herein:

(7) TABLE-US-00001 Number Component 2 Draw-redraw apparatus; 4 Sheet of metallic stock material 6 Blank and draw die 8 Blank 9 Cup 10 Sidewalls 11 Closed endwall 12 Redraw die 13 Formed cup 14 Closed endwall 15 Sidewall 16 Draw-redraw apparatus 18 Blanking die 20 Cut edge 22 Blank and draw die 24 Draw pressure pad 26 Redraw pressure pad 28 Redraw die 29 Void between blank and draw die and redraw die 30 Die center punch 31 Cavity of die center punch 32 Reform draw pad 33 Cavity of reform draw pad 34 Reform punch 35 Extension of reform punch 36 Leading surface of blank and draw die 37 Leading edge 38 Blank 40 Cup 41 Closed endwall 42 Redrawn cup 43 Sidewalls 44 Projection 45 Open end 46 Finished cup with reformed closed endwall 48 Diameter of blank 50 First sidewall height 52 First diameter of endwall 54 Second sidewall height 56 Second diameter of endwall 58 Third sidewall height 60 Third diameter of endwall 62 Projection height 64 Projection diameter

DETAILED DESCRIPTION

(8) The present invention has significant benefits across a broad spectrum of endeavors. It is the Applicant's intent that this specification and the claims appended hereto be accorded a breadth in keeping with the scope and spirit of the invention being disclosed despite what might appear to be limiting language imposed by the requirements of referring to the specific examples disclosed. To acquaint persons skilled in the pertinent arts most closely related to the present invention, a preferred embodiment that illustrates the best mode now contemplated for putting the invention into practice is described herein by, and with reference to, the annexed drawings that form a part of the specification. The exemplary embodiment is described in detail without attempting to describe all of the various forms and modifications in which the invention might be embodied. As such, the embodiments described herein are illustrative, and as will become apparent to those skilled in the arts, may be modified in numerous ways within the scope and spirit of the invention.

(9) Although the following text sets forth a detailed description of numerous different embodiments, it should be understood that the detailed description is to be construed as exemplary only and does not describe every possible embodiment since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims. To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term by limited, by implication or otherwise, to that single meaning.

(10) Referring now to FIGS. 2A-2F, a draw-redraw apparatus 16 with a novel die set of one embodiment of the present invention is provided. The apparatus 16 generally comprises a blank die 18 with a cut edge 20, a blank and draw die 22, a draw pressure pad 24, a redraw pressure pad 26, a redraw die 28, a die center punch 30, a reform draw pad 32, and a reform punch 34. The apparatus 16 is operable to form a plurality of cups from a sheet 4 of metallic stock material through a draw and wall ironing (DWI) process. Optionally, the apparatus 16 may redraw the cups. The finished cups 46 are formed from a blank 38 with an increased diameter 48 and have an inwardly oriented projection 44 in a closed endwall portion that reduces a height of the cup compared to cups formed from a similar sized blank using the prior art process illustrated in FIG. 1. Other forming operations may subsequently be used to form the cups into container bodies of any shape for any variety of products, including aerosol cans.

(11) As illustrated in FIG. 2A, a sheet 4 of metallic stock material is fed into the apparatus 16. The blank and draw die 22 is then moved in a first direction toward the blanking die 18 and the draw pressure pad 24 until a leading surface 36 of the blank and draw die 22 contacts and applies pressure to an upper surface of the sheet 4. The sheet 4 is forced against the cut edge 20 of the blanking die 18, as illustrated in FIG. 2B. The sheet 4 is sheared to form a blank 38 of a predetermined size and shape. The blank 38 is also illustrated in FIG. 2B separated from the apparatus 16 for clarity. In one embodiment, the blank 38 has a generally circular shape with a predetermined diameter 48 of between about 5 inches and about 10 inches, and in some embodiments the diameter is more preferably between about 7 inches and about 8 inches. In other embodiments the blank diameter is between about 6.75 inches and about 8.25 inches to form smaller sized cups. However, it will be appreciated by those of skill in the art that the blank 38 can have any desired diameter depending upon the desired size of the finished container. Further, the blank may have any shape, including oval, square, rectangular, triangular, circular, and/or combinations thereof.

(12) In conjunction with the movement of the blank and draw die 22 and the draw pressure pad 24, the redraw pressure pad 26 and the die center punch 30 are moved towards the redraw die 28. The bottom surface of the blank 38 is then contacted with the redraw die 28. The peripheral edge of the blank 38 is pushed in the first direction while a center portion of the blank is supported. The blank 38 is deformed, or drawn, under pressure and conforms to an interior surface of a hollow interior of the blank and draw die 22 forming a cup 40 with a predetermined, generally cylindrical shape. In an alternative embodiment a projection 44 may be formed in the cup at this stage or later as described below. The cup 40 generally includes an open end 45, sidewalls 43 with a first height 50 and a closed endwall 41 with a first diameter 52, as illustrated in FIG. 2C. In one embodiment, the cup 40 has a generally cylindrical shape, although as will be appreciated by those of skill in the art, the cup 40 can have any desired shape, including a non-cylindrical shape. An exterior surface of the redraw die 28, which comprises a smaller outer diameter than the internal diameter of the hollow interior of the blank and draw die 22, is nested within the hollow interior of the blank and draw die 22. As the blank 38 is deformed, the blank 38 transitions out of a space between the blank and draw die 22 and the draw pressure pad 24.

(13) Referring now to FIG. 2D, a portion of an upper surface of the cup 40 is contacted with the die center punch 30. Optionally, the cup 40 may be reformed (or partially redrawn) to form a redrawn cup 42 as the die center punch 30 continues to move in the first direction, conforming a portion of the cup 40 to the interior shape of the redraw die 28 under pressure. As illustrated in FIG. 2D, the material of the cup 40 is translated out from a space 29 between the blank and draw die 22 and the redraw die 28. While the cup is redrawn, the cup 40 also transitions out of a space between the redraw pressure pad 26 and the redraw die 28. The redrawn cup 42 in FIG. 2D has a closed endwall 41 with a second diameter 56 that is less than the endwall diameter 52 of the cup 40 shown in FIG. 2C. In one embodiment, the redrawn cup 42 has a diameter of between about 2.5 inches and about 5.0 inches and in another embodiment between about 3.5 inches and about 4.25 inches. For smaller cups, the diameter of the redrawn cup is between about 2.75 inches and 3.50 inches. The redrawn cup 42 illustrated in FIG. 2D has sidewalls 43 with a height 54 that may be the same as, or different from, the height 50 of the sidewalls 43 of cup 40. As will be appreciated by one of skill in the art, the cup 40 may be reformed any number of times, including zero times. Each time the cup is reformed, the diameter of the closed endwall is decrease by a predetermined amount.

(14) A closed endwall portion of the reformed redrawn cup 42 contacts the reform draw pad 32 and moves the reform draw pad 32 in the first direction toward the reform punch 34 as the die center punch 30 continues moving in the first direction forming the optional redrawn cup 42. An extension 35 of the reform punch 34 aligns substantially concentrically with a cavity 33 formed through the reform draw pad 32. In one embodiment, the extension 35 has a generally cylindrical shape with a tapered or rounded upper edge 37. However, it will be appreciated by those of skill in the art that the extension 35 can have any desired shape. In one embodiment, the extension has a cross-section with a round shape, an oval shape, a square shape, a rectangular shape, a triangular shape, a frustum, and/or combinations thereof. The cavity 33 of the reform draw pad 32 has a shape adapted to at least partially receive the extension 35 of the reform punch 34. In one embodiment, the cavity 33 has a generally circular shape with an interior diameter of between about 2.0 inches and about 2.75 inches, and more preferably between about 1.5 inches and about 3.0 inches, which is greater than an exterior diameter of the extension 35. Thus, the interior diameter of the cavity 33 is between about 40% and about 75% of the diameter of the draw pad 32, and in other embodiments between about 50% and about 65% of the diameter of the cavity 33. As will be appreciated by those of skill in the art, the cavity 33 can have any desired shape adapted to at least partially receive the extension 35. In one embodiment, the cavity 33 is substantially centered on the reform draw pad 32. In another embodiment, the cavity has a shape that is different than the cross-sectional shape of the extension.

(15) Referring now to FIG. 2E, as the die center punch 30 continues to move in the first direction to form the redrawn cup 42, the reform draw pad 32 also continues to move in the first direction. The extension 35 of the reform punch 34 projects at least partially through the cavity 33 and contacts the closed endwall portion 41 of the redrawn cup 42. The extension 35 applies force to the closed endwall 41 and reforms the closed endwall, displacing the closed endwall at least partially into a cavity 31 of the die center punch 30. The cavity 31 is adapted to at least partially receive the extension 35 and a portion of the closed endwall of the redrawn cup 42. In one embodiment, the cavity 31 has a generally cylindrical shape and is substantially concentrically aligned with the cavity 33 of the reform draw pad 32. The cavity 31 has a diameter that is at least equal to the exterior diameter of the punch extension 35. Thus, the extension 35 pushes against an unsupported portion of the closed endwall 41 of the cup 42. As the extension 35 pushes against an exterior surface of the endwall, a portion of the interior surface of the closed endwall is supported.

(16) In one embodiment, the cavity 31 has an interior diameter that is at least equal to the interior diameter of the cavity 33 of the reform draw pad 32. In one embodiment the cavity 31 has a diameter of between about 1.5 inches and about 3.0 inches, and alternatively between about 2.0 inches and about 2.75 inches. As the extension 35 applies force to the closed endwall portion of the redrawn cup 42, the closed endwall portion of the redrawn cup 42 is reformed and an inwardly oriented projection 44 is formed in a portion of the closed endwall 41 of the finished cup 46. Although the inwardly oriented projection 44 is illustrated being formed on a redrawn cup 42, it will be appreciated that an inwardly oriented projection 44 can also be formed in a cup 40 that has not been reformed using the method and apparatus of the present invention.

(17) The finished cup 46 illustrated in FIG. 2E has a closed endwall 41 with a predetermined diameter 60 of between about 2.5 inches and about 5.0 inches and preferably between about 3.5 inches and about 4.25 inches. In one embodiment, the diameter 60 is substantially the same as the redrawn cup 42 diameter 56 illustrated in FIG. 2D. The cup 46 has sidewalls 43 with a predetermined height 58 of between about 2.0 inches and about 5.0 inches and more preferably between about 2.5 inches and about 4.5 inches. The projection 44 has a predetermined height 62 of between about 0.25 inches and about 1.5 inches and more preferably between about 0.5 inches and about 1.25 inches. A diameter 64 of the projection 44 is between about 1.5 inches and about 3.0 inches. In a more preferred embodiment, the diameter is between about 2.0 inches and about 2.75 inches. The inwardly oriented projection 44 can have any desired size or shape. In one embodiment, the projection 44 has a cross-section of a truncated cone, or frustum, with a first diameter 64 proximate to the closed endwall surface 41 of the finished cup 46 that is greater than a second diameter at a top of the projection 44. In another embodiment, the projection has a generally cylindrical shape with a substantially constant diameter. Thus, the volume of the cup 40 shown in FIG. 2C when compared to the cup 46 shown in FIG. 2E is reduced by between about 15% and about 50%. More preferably, the internal volume is reduced by between about 20% and about 45%. Of course, as will be appreciated, the size (or volume) of the projection 44 may be altered. Accordingly, the internal volume of the cup 46 may change. In one embodiment, the internal volume of cup 40 is reduced by between about 5% and about 15% when the projection 44 is formed to create cup 46. In a more preferred embodiment, the internal volume of cup 46 is about 10% less than cup 40. In another embodiment, the internal volume of cup 46 is at least 7% less than cup 40.

(18) After forming the projection 44, the tooling is separated and/or extracted, and the finished cup 46 with the reformed bottom is ejected as illustrated in FIG. 2F. In one embodiment, the die center punch 30, reform draw pad 32, and the redraw pressure pad 26 each move in the second direction toward their starting positions illustrated in FIG. 2A. As the reform draw pad 32 moves in the second direction, the finished cup 46 moves out of the redraw die 28 until the bottom surface of the finished cup 46 is substantially level with the upper surface of the blanking die 18. The finished cup 46 is then ejected from the apparatus 16 and another portion of the sheet 4 of metallic stock material is fed into the apparatus 16, as illustrated in FIG. 2A. In one embodiment, the finished cup 46 is ejected laterally from the apparatus 16.

(19) Referring now to FIGS. 3A-3F, a draw-redraw apparatus 16A according to another embodiment of the present invention is provided herein. Apparatus 16A is used to form a finished cup 46 with an inwardly oriented projection 44 in a number of sequential steps in a manner similar to the method illustrated in FIGS. 2A-2F. In apparatus 16A, a reform punch 34A is positioned further from the sheet 4 of metallic stock material with respect to the redraw die 28 compared to the position of the reform punch 34 of the embodiment of the present invention described in conjunction with FIG. 2. Thus, the optional redraw of the cup 40 to form the redrawn cup 42, illustrated in FIG. 3D, is substantially completed before the reform punch 34A reforms the closed endwall portion of the redrawn cup 42, illustrated in FIG. 3E. In one embodiment, the reform punch 34A has substantially the same size and shape as reform punch 34A.

(20) Referring now to FIG. 3A, a sheet 4 of metallic stock material is fed into the apparatus 16A. A blank 38 with diameter 48 is sheared from the sheet 4 as illustrated in FIG. 3B. The blank 38 illustrated in FIG. 3B may be the same as, or similar to, blank 38 illustrated in FIG. 2B. Similarly, the diameter 48 may have the same, or similar, dimensions as discussed above in conjunction with FIG. 2B.

(21) Referring now to FIG. 3C, the apparatus 16A forms the blank 38 into a cup 40 with a predetermined shape. The cup 40 may have the same shape, endwall diameter 52, and sidewall height 50 as the cup 40 illustrated in FIG. 2C. Optionally, the cup 40 is redrawn to form a redrawn cup 42, as illustrated in FIG. 3D. The redrawn cup 42 illustrated in FIG. 3D may have the same endwall diameter 56 as the redrawn cup 42 illustrated in FIG. 2D. However, in this embodiment of the present invention, the sidewalls 43 are substantially completely re-drawn before the closed endwall 41 is reformed. Accordingly, the redrawn cup 42 illustrated in FIG. 3D has sidewalls with a generally linear cross-sectional height 54 which is distinct from the shape and size of the sidewalls of the cup 42 of the embodiment illustrated in FIG. 2D. In one embodiment, the height 54 of cup 42 illustrated in FIG. 3D is between about 2.0 inches and about 4.5 inches. More preferably, the height 54 is between about 2.5 inches and about 3.75 inches. As will be appreciated by one of skill in the art, in one embodiment, the cup 42 shown in FIG. 3D may be ejected from the apparatus 16A and used to form a container. Thus, in one embodiment, the cup 42 shown in FIG. 3D may be used to form a container with a predetermined shape and size without forming a projection in the closed end-wall of the cup.

(22) The closed endwall 41 of the redrawn cup 42 is reformed by the reform punch 34A to form a finished cup 46 with a reformed closed endwall comprising an inwardly oriented projection 44, as illustrated in FIG. 3E. The height 58 of the cup 46 is less than the height 54 of cup 42 illustrated in FIG. 3D after forming the inwardly oriented projection 44. Thus, the total internal volume, or the overflow volume, of cup 42 is reduced. More specifically, the volume of the cup 46 shown in FIG. 3E is reduced with respect to the volume of the cup 42 shown in FIG. 3D by between about 5% to about 40%. In a more preferred embodiment, the volume of cup 46 is between about 10% and about 30% less than the internal volume of cup 42 illustrated in FIG. 3D. In another embodiment, the volume of cup 46 is between about 15% and about 21% less than the internal volume of cup 42 shown in FIG. 3D. In a still more preferred embodiment, the cup 46 has a volume that is about 18% less than the volume of cup 42 of FIG. 3D. As will be appreciated by one of skill in the art, changing the size or shape of the projection 44 changes the relative volumes of cups 42 and 46. Thus, in still another embodiment of the present invention, the volume of cup 42 of FIG. 3D is reduced by at least 10% when the projection 44 is formed to make cup 46. The cup 46 and projection 44 illustrated in FIG. 3E may generally have the same shape and dimensions as the cup 46 projection 44 illustrated and described in conjunction with FIG. 2E, above. Thus, in one embodiment, the cup 46 has the same endwall diameter 60, sidewall height 58, projection diameter 64, and projection height 62 as the cup 46 of the embodiment of the present invention illustrated in FIG. 2E.

(23) Referring now to FIG. 3F, the finished cup 46 is ejected from the apparatus 16A. In one embodiment, the finished cup 46 is ejected laterally from the apparatus 16. The finished cup 46 is subsequently formed into a container body by a bodymaker by any method known to those of skill in the art.

(24) In various embodiments, pneumatic compressed air or other means provides force to one or more of the tooling components of the draw-redraw apparatus 16 described herein. For example, in one embodiment, a tooling component, such as the redraw pressure pad 26 is provided with an inner air pressure which applies a clamping force as shown in FIGS. 2B-2D and 3B-3D and another tooling component, such as the draw pressure pad 24, is supplied with an outer air pressure, which is illustrated as a clamp force in FIGS. 2B and 3B.

(25) By reforming the closed endwall portion 41 of the finished cup 46 with the projection 44, the height 58 of the finished cup 46 is decreased compared to the height of the cup 13 formed by the prior art method. Accordingly, existing tooling and bodymakers can be used to form cups 46 into container bodies that are larger. In this manner, container bodies with an increased height and/or an increased diameter can be formed. The finished cup 46 has a height 58 that is less than the height of the formed cup 13 formed using the prior art method and apparatus, although the diameter 48 of the blanks 8, 38 used to form cups 13, 46 are substantially equal.

(26) Further, reforming the closed endwall portion of the finished cup 46 enables a shorter bodymaker ram stroke and a shorter stroke redraw carriage to be used when forming the container body. Thus, the bodymaker can operate at a higher speed than is possible when forming a container body from a cup 13 without the reformed closed endwall having the inwardly oriented projection. As will be appreciated by one of skill in the art, the maximum amount that the diameter of a cup can be reduced by a bodymaker in a subsequent redraw step is known as a draw ratio. By forming an inwardly oriented projection 44 on a closed endwall portion of a finished cup 46 with a diameter corresponding to the draw ratio of a bodymaker, the amount of the material in the finished cup 46 can be increased while the height 58 of the finished cup 46 is shortened. Thus, the finished cup 46 can be formed into a container body by a conventional bodymaker.

(27) A further advantage of reforming the closed endwall portion 41 of the finished cup 46 is that the finished cup 46 of a predetermined blank size and maximum height may be formed with a smaller transverse dimension of a longitudinal cross section than would otherwise be possible. For example, a cylindrical cup with reformed closed endwall and specified maximum height may have a smaller diameter than a cylindrical cup of the same height made from a blank of the same size. In one embodiment of the present invention, the diameter 60 of a finished cup 46 with a cylindrical shape having a reformed closed endwall is approximately 5% less than that of a cylindrical cup 13 of the same height without an inwardly oriented projection 44, although both cups 13, 46 are formed from substantially the same size blank 8, 38. This reduction in the transverse dimension of the finished cup 46 facilitates the redraw operation in the bodymaker. The redraw operation in the bodymaker must reduce the internal diameter of the cylindrical cup to the diameter of the finished container body. Reduction of the cup diameter to the finished container body diameter is most reliably accomplished when the reduction in the diameter of the cup is small. If the attempted diameter reduction is too large, the redraw operation will fail by any of several means, including wrinkling or rupture of the cup material. In one embodiment, the reduction in diameter from cup diameter to container body diameter, as compared to the cup diameter, is limited to not more than 40%. In another embodiment, the reduction is limited to not more than 35%.

(28) The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limiting of the invention to the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments described and shown in the figures were chosen and described in order to best explain the principles of the invention, the practical application, and to enable those of ordinary skill in the art to understand the invention.

(29) While various embodiments of the present invention have been described in detail, it is apparent that modifications and alterations of those embodiments will occur to those skilled in the art. Moreover, references made herein to the present invention or aspects thereof should be understood to mean certain embodiments of the present invention and should not necessarily be construed as limiting all embodiments to a particular description. It is to be expressly understood that such modifications and alterations are within the scope and spirit of the present invention, as set forth in the following claims.