Abstract
The principles of the present invention further provide both a shaped metal container and its preforms that exhibit a rounded grain structure characteristic created by an annealing process and a method for making a shaped metal container. The process of making said metal container results in a quicker process time and uses less metals (at least 10% metal weight savings), thus allowing for a decrease in the costs of making such shaped metal containers. A shaped metal container may include work hardened rolled sheet-metal defining a sidewall, an opening, and a base, where at least one section along the sidewall has grains with an average aspect ratio less than about 4 to 1.
Claims
1-10. (canceled)
11. A shaped metal container comprising a container middle section connected at one end to a container bottom section, and at the other end to a top section, at least part of the container top section, the container middle section and/or the container bottom section being shaped by necking and another part being shaped by outwardly shaping, such that at least one of the middle section diameter Dm, the bottom section diameter Db, and the top section diameter Dt is greater than, and at least one of the middle section diameter Dm, the bottom section diameter Db and the top section diameter Dt is smaller than the cylinder diameter Dc of the container preform from which the shaped metal container has been made.
12. The shaped metal container according to claim 11, wherein a necked container top section is provided with a thread and/or a bead provided with at least one axial interruption.
13. The shaped metal container according to claim 11, wherein the container middle section is outwardly shaped, and the diameter Dm is greater than the diameter Dc, and the bottom section is outwardly shaped with the diameter Db greater than the diameter Dc.
14. The shaped metal container according to claim 11, wherein the container top section, container middle section and/or container bottom section is/are provided with inwardly and/or outwardly extending strengthening of aesthetic structures.
15-32. (canceled)
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] Illustrative embodiments of the present invention are described in detail below with reference to the attached drawing figures, which are incorporated by reference herein and wherein:
[0041] FIGS. 1A-1D are illustrations including perspective views, (FIGS. 1A and 1B) a side view (FIG. 1C), and a cross-sectional view (FIG. 1D) of an illustrative shaped metal container that may be formed utilizing the principles of the present invention;
[0042] FIGS. 2A and 2B are illustrations of a side view and cross-sectional view of another illustrative shaped container including inwardly extending structures that may be formed utilizing the principles of the present invention;
[0043] FIGS. 3A-3C are illustrations of another illustrative shaped container in side view, cross-sectional view and a droplet magnification, respectively, and with outwardly extending structure;
[0044] FIGS. 4A-4K are illustrations of an illustrative metallic bottle progressively formed at each step of an illustrative process for making a shaped metal container utilizing the principles of the present invention;
[0045] FIGS. 5A-5K are illustrations of an illustrative metallic bottle being progressively formed at each step utilizing an alternative process for making a shaped metal container;
[0046] FIGS. 6A-6D show a blow forming of a shaped metal container with FIGS. 6C and 6D being illustrations that depict droplet magnifications of the transitional section between sidewall and foot;
[0047] FIGS. 7A-7D are illustrations of perspective views, side view and cross-sectional view, respectively of a necked container top section with bead according to the principles of the present invention;
[0048] FIGS. 8A-8C are illustrations that show inward shaping by necking in the method of making a shaped metal container using a supporting sleeve;
[0049] FIGS. 9A-9C are illustrations of illustrative alternative shaped metal containers according to the principles of the present invention;
[0050] FIG. 10 is an illustration an alternative embodiment for an illustrative finish of a shaped metal container of FIG. 9C;
[0051] FIG. 11 is an illustration of an alternative for container top section of a shaped metal container according to the principles of the present invention;
[0052] FIGS. 12A and 12B are illustrations of a side view of a preform and shaped aerosol container;
[0053] FIG. 13 is a flow diagram of an illustrative process for producing shaped metal vessels in accordance with the principles of the present invention;
[0054] FIG. 14 is all illustration that depicts an illustrative cross-section of metal container formed from annealing and shaping a cylindrical metal preform utilizing the principles of the present invention; and
[0055] FIGS. 15A and 15B, 16A and 16B, 17A and 17B, and 18A and 18B are companion photographs and analysis images of respective illustrative portions of the metal container of FIG. 14 that show the effects of annealing, blow forming, and die necking on grains of metal of the metal container.
DETAILED DESCRIPTION OF THE DRAWINGS
[0056] FIGS. 1A-1D are illustrations of a shaped metal container 100 that may be formed utilizing the principles of the present invention. The shaped metal container 100 is a one-piece beverage container having an integral bottom. The container 100 includes a container middle section 102 defined by middle section parts 104, 106, and 108. The container middle section 102 is connected at one end to a container bottom section 110 including a transitional section 112, a foot 114, and a central dome section 116. At the other end, the container middle section 102 is connected to a container top section 118 including a bead 120, a thread 122, and an inwardly curled end 124 defining a container opening 126. The shaped metal container 100 may include a bottom section having a diameter Db of, for instance, 53 mm. In one embodiment, the container middle section 102 may have a largest diameter D ml of 53 mm, and a smaller diameter Dm2 of 47 mm. The container top section 118 may have a top section diameter Dt of 25 mm. The height of the shaped container 100 is, for instance, 185 to 190 mm. It is apparent from FIG. 1C that the diameter of the shaped metal container 100 may gradually change in between the various identified diameters. The body wall of the shaped metal container 100 may have a thickness of 0.14 to 0.20 mm, such as 0.175 mm. The gauge of the original material may be about 0.30 to about 0.40 mm, such as 0.35 mm, which is substantially the thickness of the dome section 116. The content of the shaped metal container 100 may be from 250 to 280, such as 270 ml. It should be understood that shaped metal containers with smaller or greater dimensions and/or volume are also possible.
[0057] FIGS. 2A and 2B are illustrations that show an alternative shaped metal container 200 in side view and cross sectional view, respectively. The same structural features as in FIG. 1, are identified by the same reference numbers. The container middle section 102 is provided with axially extending and inwardly extending structures or flutes 202. These flutes 202 provide more strength into the container middle section 102 and/or may also provide the shaped metal container 200 with an improved aesthetic appearance. The flutes 202 may additionally and/or alternatively extend in a non-axial direction.
[0058] FIGS. 3A-3C are illustrations that show an alternative shaped metal container 300 in side view, cross-sectional view and a droplet magnification, respectively. Again, the same structural features are identified by the same reference numbers. The container middle section 102, and in particular the middle section parts 106 and 108 are provided with outwardly extending structures or flowers 302. The flowers 302 extend outwardly and may be equally spaced apart over the circumference of the container middle section 102. These structures 302 provide strength and/or a desired aesthetic to the shaped metal container 300, and may extend non-axially.
[0059] The skilled person will appreciate that the structures 202 and 302 may also be incorporated in the other sections of a shaped metal container according to the principles of the present invention, and may be present in one and the same shaped metal container. The structures 202 and 302 may also be configured to provide the appearance of a logo of the company that has filled or will fill its content into the shaped metal container. In addition to such logo, imprints may also be applied to the outer surface of the shaped metal container.
[0060] FIGS. 4A-4K (collectively FIG. 4) are illustrations of a shaped metal bottle being formed at each step of a process 400 for making the shaped metal container shown in either FIG. 2 or 3. The process starts with a circular disc shaped blank 402 in FIG. 4A that is formed into a cup 404 in FIG. 4B including cylindrical wall 406 and a bottom 408 (see FIGS. 1A and 1B). The thickness of the cylindrical wall is slightly less than the thickness of the blank 402, but the thickness of the bottom 408 is substantially the same as the thickness of the blank 402. By drawing and ironing, cups 410 and 412 in FIGS. 4C and 4D, respectively, are formed with progressively smaller diameter and increased height (FIGS. 3C and 3D). The cup 412 is then trimmed, resulting in preform 414, as shown in FIG. 4E. The preform 414 has a cylindrical body 416 with a diameter Dc, see FIG. 4E. The thickness of the preform 414 is generally within the range of 0.10 to 0.40 mm, such as 0.14 and 0.26 mm, such as 0.16 to 0.24 mm. This preform 414 is subjected to an annealing treatment, as described further herein, of its entire height in an oven (not shown). The annealing may result in a yield strength for the preform 414 within the range of about 250 to 650 MPa, such as 270 to 630 MPa, such as 280 to 600 MPa. The ultimate yield strength to be acquired by the annealing treatment is further dependent on the metal and/or thickness of the cylindrical wall of the preform 414. The annealed preform 414 is subjected to an outwardly shaping of the cylindrical body 416 to the preform 418 shown in FIG. 4F.
[0061] The container middle section 102, container bottom section 110 and the container top section 118 all have been subjected to a blow forming shaping, whereas in the container middle section 102, the structures 18 have been formed. The blow formed preform 418 may then subjected to an inwardly shaping by necking of the top section 420 of the blow formed container shown in FIG. 4G. After carrying out a necking procedure in multiple necking rings, such as 1 to 40 necking rings, such as 1 to 30 necking rings, preferably 1-20 necking rings, dependent on the wall thickness, the hardness and the yield strength of in particular the blow formed top section 420 is increased. The resulting blow formed and necked preform 422 is then subjected to a beading operation for forming the beads 120 and 424, as shown in FIG. 4H. The formed preform 426 is subjected to a further necking operation for forming a necked outer section 428 by using 1-10 necking rings, such as 1-5 necking rings, as shown in FIG. 4I. The preform 430 obtained is then subjected to a curling operation for curling the necked section 428, as shown in FIG. 4I. The preform 432 of FIG. 4J is finally subjected to a threading operation for forming the thread 122, thereby forming the shaped metal container 200, for example.
[0062] The enlarged view of the container top section 118 as shown in FIG. 4K shows that the bead 120 is not continuous over the circumference of the neck 434 of the shaped metal container 200, but may be interrupted over its circumference, thereby forming axial interruptions 436 in between the bead parts 438, which increases the axial strength of the neck 434. In one embodiment, the bead 120 is not continuous over the circumference of the neck of the shaped metal container 200, but may be interrupted over its circumference, thereby forming axial interruptions in between the bead parts, which increases the axial strength of the neck. The neck thereby acquires an axial strength withstanding an axial load of more than 1100N, such as 1200 to 1300N. Without the presence of these bead interruptions, the top load resistance would have been only about 1000N. It is noted that within the concept of the invention it is also possible to first carry out the necking step as illustrated by FIG. 4G, and thereafter the blowing step illustrated by FIG. 4F.
[0063] FIGS. 5A-5K are illustrations of a shaped metal bottle being progressively formed at each step of process 500 utilizing an alternative method according to the principles of the present invention for making a shaped metal container 200. The same reference numbers are used for identifying the same structural features as disclosed and described in relation to FIGS. 4A-4K. The difference in the method of making the shaped container 200 is that the preform 414 of FIG. 5E is not subjected after the annealing treatment to a blow forming operation, but the preform 414 is subjected to a necking operation as was used in the method according to FIG. 4 to the blow formed preform 418. The preform 414 is subjected to a necking operation using necking rings in a number of 1-30, such as 1-25 or 1-20 necking rings, as illustrated in FIG. 5F. The preform 502 includes a neck container top section 504 that is connected to the middle section part 114 of which the diameter gradually increases to the diameter Dc of the cylindrical wall or body 416. Subsequently, the container middle section 102 of the preform 502 may be subjected to an annealing procedure, as further described herein, by induction annealing, for example, whereby the yield strength is decreased, and the ductility and elongation-to-break increased. After the annealing treatment, the preform 502 is subjected to a blow forming operation of the container middle section 102 and part of the container bottom section 110, as illustrated by FIG. 5G. It is noted that within the concept of the invention that it is also possible to first carry out the necking step, as illustrated by FIG. 5G, and thereafter the blowing step, as illustrated by FIG. 5F.
[0064] Produced by the process 500 is essentially the same preform 422 as produced in the method 400 according to the principles of the present invention illustrated in FIG. 4.
[0065] Hereafter, the preforms 426, 430, and 432 are produced as shown in FIGS. 5H-5J, and ultimately is formed the shaped metal container 200 of which detail is shown in FIG. 5K.
[0066] The shaped metal container may be formed from aluminum or steel from suitable alloys and/or tempers.
[0067] Generally, the blank 420 may have a diameter of 100-150 mm, such as 125 to 135 mm and a thickness that may be of 0.30 to 0.60 mm, such as 0.40 to 0.50 mm. The cups 404-412 may have a diameter of 80-100 mm, 60-70 mm and 40-50 mm, respectively. The preform 414 may have a diameter of 40 to 50 mm, such as 45 mm, for producing the shaped metal container 100 or 200, as described in FIGS. 1, 2, and 3. These dimensions are dependent on the dimensions of the ultimate shaped metal container, and can be selected by the skilled person.
[0068] FIGS. 6A-6D are illustrations that show more in detail the outwardly shaping of the preform 414 by blow forming. However, it is noted that other mechanical techniques, such as mechanical expansion or stretching may also be used. With the blow molding variant, it is also possible to provide the shaped metal container with strengthening and/or ornamental structures, and, if desired, customer logos.
[0069] FIG. 6A is an illustration that shows preform 418 after blow forming. The preform 418 includes a substantially cylindrical container top section 118 of which the diameter is substantially the same to the diameter Dc of the cylindrical body 416 of the preform 414. For instance, the cylindrical diameter Dc may be 45 mm. The container middle section 102 and part of the container bottom section 110 has also been subjected to the blow forming operation. Resulting in a diameter D ml of for instance 53 mm, a diameter Dm2 of 47 mm and a diameter Db of 53 mm, see also FIG. 1C and FIG. 6D.
[0070] FIG. 6B is an illustration that shows blow forming unit 600 including two separable mold parts 602 having an inner surface 604 corresponding with the outer shape of the blow formed container middle section 102 and container bottom section 110 as shown in FIG. 6A. The inner surface 604 also includes the surface details dictating the formation of the structures 302. The preform 414 is mounted in the blow forming unit 600 resting on a support 606 dictating the shape of the dome section, and a mold plug 608 is inserted into the preform 414. It is noted that in an alternative form, a mold cap can be used that is pressed on the free end of the preform 414 or extends and is clamped to the outside of the upper part of the preform 414. An airtight connection may be formed with the preform 414 to perform a blow process utilizing the principles of the present invention. The mold plug 608 is provided with an air inlet 610, so that the preform 414 may be subjected to high pressure, such as 30-50 bar, such as 40 bar. The high pressure blow may result in a blow forming of the preform 418 to the extent that is allowed by the mold, and, in particular, the mold parts 602.
[0071] As shown by the droplet magnification of FIG. 6C, a bottom profile 612 may be formed by defining the dome section 116, the foot 114, the transitional section 112, and the body wall 614.
[0072] Instead of a cylindrical body wall 418, it is possible to provide the foot 114 with an outward bulging transitional section 616 as shown in FIG. 6D. Thereto, it is advisable that with the mold plug 610, a compression load is performed on the preform 414 during the blow forming operation.
[0073] In addition, and as discussed above, it is beneficial that at least the container middle section 102 and the bottom section 110 have been subjected to the annealing treatment, thereby reducing the yield strength and increased ductility and elongation to failure. The axial load applied may be in the order of 1000 to 1800N, such as 1200-1700N, such as 1600N.
[0074] As shown in FIG. 6D, the thickness of the bottom 116 is substantially of the same thickness as the thickness of the blank 402 and may be in the order of 0.30 to 0.60 mm, such as 0.40 to 0.50 mm, such as 0.45 mm. The thickness of the body wall 614 is substantially less, and may be in the range of 0.15 to 0.25 mm, such as 0.20 mm.
[0075] The elongation-to-break of, in particular, the container middle section and bottom section may be about 10% to 25%, such as 15% to 20%, such as 18%. Such elongations are possible due to the prior annealing treatment, as described further herein, and the selection of the proper thickness and preferably the alloy and/or temper used. Obviously, these selections can be made by the skilled person and will also be dependent on the selection and type of work hardened Al metal, such as aluminum and steel. A suitable alloy, for example, is the aluminum alloy 3104-H19.
[0076] Work-hardened metal, such as aluminum or steel, and its alloys is a term known to one skilled in the art as the strengthening of a metal by plastic deformation. It is further understood that work hardened aluminum alloy will also result in the presence of greater residual stresses and the high dislocation density in the metal. The residual stresses and dislocation density can lead to higher strength and reduced elongation.
[0077] The term “rounded” used herein when describing annealed grain structure means any type of shape (i.e., geometric or non-geometric) that includes space both inside lines defining the shape and the lines of the shape.
[0078] FIGS. 7A-7D are illustrations that show a perspective view, a side view, and a cross-sectional view of the container top section 118 of a shaped metal container according to the principles of the present invention. The container top section 118 is provided with a bead 120 that includes bead parts 438 interrupted by interruptions 436 that are equally spaced apart over the bead circumference. As discussed hereinbefore, the provision of the interruptions 436 increases the axial resistance from about 800 to 1200N, to about 1200 to 1600N, such as 1300-1400N. Such increase in axial resistance is beneficial for customers using the shaped metal containers during filling and capping of the shaped metal container while the container is handled and supported at the bead 120. During capping, an axial load may be exerted on the container top section 118 that is withstood by the bead 120, as previously described.
[0079] FIGS. 8A-8C are illustrations that show an illustrative necking operation 800a-800c (collectively 800), of the preform 418 thereby transformed in the preform 422 provided with the necked container top section. During the necking operation, a necking ring 802 is pushed over the container top section 804, with the diameter of the necking ring opening being slightly less than the outer diameter of the container top section 804. The necking operation 800a results in a small decrease of the outer diameter of the container top section 804. By repeatedly performing such necking operation with necking rings of gradually smaller ring opening diameters, the container top section 804 acquires ultimately the desired outer diameter 806, such as a diameter in the range of about 20-40 mm, such as 25 mm. As stated hereinbefore, the necking ring 802 exerts and axial load on the preform, which load is in the order of 700N-1200N, such as 1000N. This load may be too large for relatively weak parts of the preform, such as the transitional section 808 near the foot of the shaped metal container, the lower part of the container middle section 810 and near the maximum diameter in the upper part of the container middle section 812. Still, the necking operation may be carried out without failure of the preform during the necking operation, and thereto the principles of the present invention provide a supporting sleeve 814 that supports the preform, and contacts the preform with contact surfaces 816-820 located at or near the weaker sections of the preform. Obviously, the support sleeve 814 may also be used for handling transporting the preform and later shaped metal and thereto the support sleeve 814 may be provided with a related outer handling structure 822.
[0080] FIGS. 9A-9C are illustrations that show alternative forms for a shaped metal container 900a-900c utilizing the principles of the present invention.
[0081] FIG. 9A is an illustration of another illustrative metal shaped container 900a including a container bottom section 902 having a diameter equal to the diameter of the preform 414. A lower part 904 of the container has middle section in diameter smaller than the preform 414, and thereto the preform 414 was subjected to a necking operation extending up to the bottom section 902. Thereafter, the neck portion is subjected (after annealing) to a blow forming operation, thereby providing a profile as shown in FIG. 9A for the outwardly bulging part 906 of the container middle section. The container top section 908 has the same diameter as the preform 414 and is provided with a curl 910 to which is seamed a closure 912.
[0082] A shaped metal container 900b according to FIG. 9B has a bottom section 914 and an upper part 916 of the container middle section having a diameter smaller than the diameter of the preform 414. This diameter may, for instance, be as small as 23 mm. The lower part 918 of the container middle section has a diameter larger than the preform 414, whereas the upper part 920 has a diameter equal to the preform 414. The container 900b may be produced by first necking the preform 414 over its entire height, and thereafter annealing at least the parts 918 and 920 that are then subjected to the blow forming operation, thereby providing the container 900b with the form as shown in FIG. 9B. The top end section is again provided with a curl 922 onto which is snapped a cap 924.
[0083] FIG. 9C is an illustration of yet another illustrative shaped metal container 900c of which bottom section 926 is subjected to a blow forming operation, and neck section 928 is subjected to a necking operation and thereafter provided with bead 120 and a thread 122 onto which a screw cap 930 may be screwed.
[0084] FIG. 10 is an illustration that shows an alternative embodiment for the neck 1028. A neck portion 1000 is provided with a metal or plastic sleeve 1002 carrying at its outside the bead 120 and the thread 122. The cap 1030 is screwed on the thread 122. Accordingly, it is possible within the subject of the invention that the necked part of the shaped metal container is provided with a sleeve attached to the container top section and provided with the thread 122, or the bead 120 or with both.
[0085] FIG. 11 is an illustration that shows an alternative embodiment of a neck portion 1100 in which the bead 120 is provided with the interrupted bead part 438 and the interruptions 436. At the same time, the thread 1102 is provided with thread interruptions 1104 also adding to the axial resistance of the neck portion 1100.
[0086] FIG. 12A is an illustration of an illustrative preform 1200a for an end product, such as beverage container, a carbonated beverage container, or an aerosol container, by utilizing the processes described herein. The preform 1200a may have a cylindrical body 1202 with a cylindrical diameter Dc, and a necked upper portion 1204 having a diameter Dt, and with a curl 1206 defining an opening 1208 of the preform 1200a. The preform 1200a is subjected to an annealing treatment in the upper middle section 1210a and lower middle section 1212a of the cylindrical body 1202. The annealing treatments may be carried out at the same time or sequentially in any order. When the annealing treatments arc carried out at different temperatures and/or during different time periods, then a low annealing temperature treatment may be performed prior to a high annealing temperature treatment. The use of an induction annealing process enables short periods of time of annealing, thereby increasing production rates.
[0087] The annealed upper middle section 1210a, as shown, is subjected to an inwardly shaping illustrated by arrow 1214, which may be carried out by inward necking or other suitable technique. From the inward necking process, an inwardly shaped upper middle section 1210b results.
[0088] The annealed lower middle section 1212a is subjected to outward shaping by any suitable technique illustrated by arrows 1216, such as blow forming or mechanical shaping to cause an outwardly shaped lower middle section 1212b to be created. The end product 1200b is tailored having at the same time and inwardly shaped section with diameter D1m, and outwardly shaped section with diameter D2m, which arc both different from the original diameter Dc.
[0089] In accordance with the principles of the present invention, a shaped metal container, such as an aluminum bottle configured is to be lightweight such that shipping and packaging costs may be reduced. Such a lightweight shaped metal container may be reduced. Such a lightweight shaped metal container may be reduced to less than 20 grams, and as low as about 17 grams or lower. The lightweight shaped metal container is to be strong enough to endure shipping and consumer use environments. To achieve such results, annealing, blow forming and multi-die necking processes (see FIG. 13) are utilized in conjunction with conventional metal container processes to achieve a novel grain structure of the metal container.
[0090] With regard to FIG. 13, a flow diagram of an illustrative process 1300 for producing shaped metal vessels in accordance with the principles of the present invention is shown. The process 1300 may start at step 1302, where an uncoiler is utilized to uncoil rolled sheet metal from a roll. As understood in the art, rolled sheet metal is work hardened during the rolling process, such that grains of metal are elongated to have aspect ratios that are typically greater than 5.0, and often 7.0 and higher. Moreover, the grains appear to be stacked like “pancakes” and in an orderly arrangement, as further shown in FIGS. 13A-13B. In operation, the uncoilers holds a sheet metal coil vertically, and feeds a strip of the rolled sheet metal into first forming operations, including a lubrication step 1304 and a cupper step 1306, which may use a cutting tool to form a “blank” (see FIG. 5A) and reshaping tool that draws the blank to form a cup (see FIG. 5B). In one embodiment, multiple cupper steps may be utilized to produce an elongated cup (see FIG. 5C). The cup may have an initial height formed by the cupping tool. During the cup forming operation, very little material thinning occurs. In the event of having multiple cupping operations at step 1306, an additional draw of the initial cup occurs, whereby height of the cup is increased. In one embodiment, additional lubricant may not be used in the second cupping operation. As a result of a second cupping operation, thickness of the walls may be reduced slightly, typically on the order of less than 1/10 of a millimeter.
[0091] At step 1308, a body maker step may be configured to significantly elongate the cup formed by the cupper step 1306. The body maker step 1308 may include a wall ironing stage that uses ironing rings that progressively reduce sidewall thickness, while at the same time, significantly increase tensile properties. As an example, the sidewalls of the cup may be thinned from 0.60 mm to around 0.15 mm. Additionally, a base dome profile may also be formed in the body maker, which is conventional practice for making cans. Resulting from the body maker is an extended cylindrical preform (see FIG. 5D). At step 1310, a trimmer process may be used to trim the cylindrical metal preform so that the sidewalls have a substantially similar height along the circumference of the cylindrical preform.
[0092] The cylindrical metal preform may be washed and dried at steps 1312 and 1314. In drying the cylindrical metal preform, a washer oven may heat the cylindrical metal preform to less than about 200° C. In being about a certain temperature, the temperature may be a few degrees higher or lower than the certain temperature and be within an appropriate temperature range in accordance with the principles of the present invention. It should be understood that other temperatures may be utilized to dry the cylindrical metal preform, but that the temperatures used do not exceed a temperature that would alter the structural composition (e.g., grains) of the metal, such as by annealing to reduce tensile strength. By washing and drying the cylindrical metal preform, lubricant and dirt are removed from the surface so as to ensure that the metal surface is suitable for coating application and adhesion processes.
[0093] In accordance with the principles of the present invention, an annealing step 1316 is utilized to anneal a portion of or an entire cylindrical metal preform. Contrary to conventional heating, annealing heats a portion of or the entire cylindrical metal preform (i) to temperatures that exceed typical heating processes for rolled sheet metal used for beverage and/or aerosol containers. Moreover, as a result of the annealing process described herein, further processing and fabrication of a “useable” container from a fully annealed preform may be performed.
[0094] As a result of the significantly altered grain structure from the increased heated cylindrical metal preform is the ability to perform blow molding at room temperature to produce larger expansion than possible with lower or no annealing having been performed. As an example, blow molding of the rolled sheet metal with little or lower temperature annealing at room temperature results in a maximum expansion of about 8%, and generally below 3%, whereas it has been realized after annealing that an increase expansion of the cylindrical metal preform of upwards of or over 18% can be achieved at room temperature. As an example, one high-pressure blow may expand a 45 mm diameter cylinder to a 53.0 mm diameter cylinder in a single blow operation at room temperature. The annealing may be performed in the number of different ways, including (1) full body annealing using a recirculating air box oven, (2) full body annealing using a single station induction unit, and (3) localized annealing using a single station induction unit. It should be understood that additional and/or alternative annealing processes may be utilized in accordance with the principles of the present invention. Moreover, at least one section along the sidewall may have grains with an average aspect ratio less than about 4 to 1, where the section(s) along the sidewall is a horizontal section along a particular height of the sidewall that extends around the sidewall. In one embodiment, grains on opposing sides of the section(s) along the sidewall have an average aspect ratio higher than the average aspect ratio of the section(s) along the sidewall.
[0095] As previously described, rolled sheet metal is work hardened and has a highly organized grain structure with elongated grains (e.g., aspect ratio greater than 7) as a result of stretching the metal when forming the sheet. TABLE I shows a few data points of the average aspect ratio for the rolled sheet metal that undergoes the annealing process, as described herein.
TABLE-US-00001 TABLE I Status versus Average Aspect Ratio Status Average Aspect Ratio Before Annealing 7.03 (work hardened rolled sheet metal) After Annealing 1.48 4% Expansion 1.54 18% Expansion 1.71 After Die Necking 1.36
[0096] Continuing with FIG. 13, an internal spray operation may be performed at step 1318, where the annealed cylindrical metal preform receives an internal spray coating along with the spray being cured in a spray oven at step 1320. Temperature of the spray oven is in the range of about 200° C. The cylindrical metal preformed may also be externally coated by an external coater at step 1322, and the external coat may be cured in a coater oven at step 1324. At step 1326, the preform may be decorated by printing, as understood in the art, and the ink may be cured in a print oven at step 1328. At step 1330, a varnish coater may be used to apply a varnish to protect the decorations, and the varnish may be cured by a varnish oven at step 1332. Again, temperatures of the ovens are typically in the range of about 200° C.
[0097] As it is conventionally performed on metal bottles used for consumer goods, a multi die necking process 1334 is performed. As understood in the art, the conventional multi-die necking process 1334 may include upwards of 50 or more steps depending on the configuration of the metal container. In the event of the metal container appearing in a bottle shape, a higher number of die necking operations are utilized to provide for a smooth transition along a neck of the metal bottle. However, the use of die necking can be used to either increase or decrease a diameter of the metal container, so the multi-die necking operation 1334 is generally used to form a body shape and/or a neck of a metal bottle. Because die necking is a complex and time consuming operation, the more die necking steps that can be eliminated, the faster manufacturing of bottles can occur with a reduction in loss due to errors in the die necking processes.
[0098] In accordance with the principles of the present invention, rather than simply performing the multi-die necking operation 1334, a blow forming operation 1336 and multi-die necking operation 1338 may be performed on the annealed cylindrical metal preform. The blow forming operation 1336 may be performed at 40 Bar or higher using high-pressure air or other medium. Again, the blow forming operation 1336 may be performed at room temperature and produce a significantly expanded container due to the annealing performed at step 1316, as previously described. As a result of performing the blow forming operation at step 1336 and multi-die necking operation at step 1338, the metal may be work hardened, whereby the grains of the metal may be stretched to have a higher aspect ratio than that after being annealed, as previously described, along with having increases in tensile strength in the neck area following successive die necking operations. By expanding and contracting annealed cylindrical metal preform, the metal is work hardened and the aspect ratio of the grains may increase and decrease, respectively (see TABLE I).
[0099] Following the multi-die necking at step 1338, a leak testing step 1340, washing step 1342, and palletization step 1344 may be performed. Once palletized, the shaped metal containers may be provided to a filling line to fill the metal containers with a product, such as a soft drink. Although the annealing 1316 is shown to be performed prior to decoration of the shaped metal container, decoration technology that is capable of being heated to temperatures of 300° C. or higher may enable the annealing 1316 to be performed at a different position within the process 1300.
[0100] As a broad generalization, steps 1302-1314 define a process for forming the cylindrical metal preform, steps 1318-1332 define a decoration process, steps 1336 and 1338 define a reshaping of the cylindrical metal preform into a shaped metal container, and steps 1340-1344 define a post-metal container shaping process including inspection, cleaning, and packaging.
[0101] As previously described, the annealing and blow forming/multi-die necking steps 1316 and 1336 enable the ability to produce shaped metal containers that have heretofore been unable to be produced due to limited expansion capabilities of rolled sheet metal for use in consumer packaging, such as soft drinks and carbonated beverages. With the inclusion of the annealing and blow forming/multi-die necking steps 1316 and 1336/1338, non-symmetrically shaped containers may be produced using a single blow at room temperature making lighter weight metal packages.
[0102] As a result of utilizing the principles of the present invention, a number of features and/or results are provided that are not otherwise available through use of a conventional multi-die necking approach, including:
[0103] (1) A smaller diameter preform may be used, which reduces a finished shaped metal vessel weight, and also benefits downstream processes by eliminating metal shaping processing steps that would have to be performed or simplifying the metal shaping processing.
[0104] (2) The annealing of the cylindrical preform may recrystallize the work hardened “pancake”-like grains of the rolled sheet metal, which eliminates built-in stresses that are inherently part of the rolled sheet metal. Such elimination of the built-in stresses considerably increases ductility and, thus, formability. As an example, in the case of using 3014 H19 alloy, an increase in elongation extends from less than 3% (after wall ironing) to about 18%.
[0105] (3) The use of the blow forming between the shaping and decoration steps enables the annealed cylindrical metal preforms to be shaped in ways that would be impossible by multi-die necking alone. For example, the blow forming stage allows inclusion of flutes, surface patterning, embossing, etc., to be included in the overall design without having to perform additional necking processes. These flutes and the other patterns may provide for work hardening at those locations, which provide structural support for the shaped metal vessel.
[0106] (4) Because the blow molding process is frictionless, the vast majority of the elongation generated by the annealing process may be used in body shaping.
[0107] (5) A combination of annealing and blow forming means that a large number of multi-die necking stages are significantly reduced, and mechanical expansion stages may be eliminated.
[0108] (6) An entire lower body of the shape metal container can be formed in a single operation without inducing any work hardening or stresses in the neck area.
[0109] (7) A potentially more robust and less complex production process may be achieved, and a number of multi-die necking stages may be reduced significantly (e.g., 40 or more multi-die necking stages for producing a particular shaped metal container may be reduced to about 20 multi-die necking stages).
[0110] (8) A reduction in the number of neck forming stages may be reduced, which necessarily reduces the number of trimming and lubrication stages plus the associated equipment for trimming and lubricating.
[0111] (9) A significant reduction of risk of splits during curl formation of a lip of the shape metal vessel may results from recrystallization of the finish area of the metal container.
[0112] (10) Quick shape change-overs on a production line may be possible if the shaped differences are limited to an area of the sheet metal vessel formed by the blow forming or other metal shaping processes.
[0113] The effect of annealing and blow forming on hardness and grain structure of various sections of preforms achieve results previously not possible. Preforms made with the process of FIG. 13 and FIGS. 4A-4F, for example, provide for lightweight shaped metal containers described herein. It should be understood that other embodiments of the methods according to the principles of the present invention may be used in the alternative. The preform 414 was produced from the blank 402 made of aluminum alloy 3104-H19. The blank 402 had a thickness of 0.2 mm. The preform 414 was subjected to full body annealing in a box oven set at 350° C. for about one minute (total time in the box oven is 3 minutes), or use of an induction coil to heat metal of the preform to 350° C. for 1-2 seconds.
[0114] Annealed test shells were subjected to a tensile test (LO: 49.3 mm, 3 mm/min, at 20° C.), according to NF EN ISO 6892-1 method A. The annealed test shell had the following tensile strength characteristics:
TABLE-US-00002 Average Rm 192 MPa Average Rp0.2 90 MPa Average Elongation 20.1%
[0115] Rm: the tensile strength Rm indicates the limit at which the metal tears under pressure, i.e., the maximum tensile stress;
[0116] Rp 0.2: Stress at which the metal undergoes a 0.2% non-proportional (permanent) extension during a tensile test;
[0117] Elongation: the maximum elongation at break.
[0118] After annealing or after annealing and blow forming, the preforms were subjected to a test for hardness. The Vickers Hardness (MPa) was measured in various sections over the height of the annealed preforms, and of the annealed and blow formed preforms. The Vickers hardness was measured according to NF ISO 6507-1. The results were as follows in TABLE II:
TABLE-US-00003 TABLE II TEST RESULTS - HARDNESS Height from base (mm) Annealed Annealed and blow formed 170 53.0 52.8 130 51.8 51.4 90 51.8 74.8 50 53.5 60.0 15 52.6 70.9 0 47.8 58.3
[0119] The sections at a height of 170 mm and 130 mm were sections subjected to a necking operation and were not subjected to blow forming. The sections at 90 mm and 15 mm were sections that had been subjected to blow forming. The section at 50 mm substantially retained the original diameter and was not, or to a minor extent, subject to blow forming. The hardness results given in TABLE II above, show that the blow forming, which is a form of work hardening, resulted in an increased hardness.
[0120] FIG. 14 is an illustration that depicts an illustrative metal container formed from annealing and shaping a cylindrical metal preform utilizing the principles of the present invention. The metal container includes four portions identified as A (base), B (lower middle), C (upper middle), and D (neck) at which different amounts of work hardening is performed. The effect of annealing, blow forming, and necking on the grain structure of the metal was studied. The grain structure was determined by performing standard surface etching and visual inspection via microscopy. Preform samples were cut from the preform in a longitudinal cross-sectional manner across the thickness of the preform. The preform samples were mounted in resin, and after polishing and etching of the cutting surface, photographs were taken (at magnification to scale).
[0121] FIGS. 15A and 15B, 16A and 16B, 17A and 17B, and 18A and 18B are companion photographs and analysis images of respective illustrative portions of the metal container of FIG. 14 that show the effects of annealing, blow forming, and die necking on grains of metal of the metal container. The preform samples were taken at various heights of preforms, as depicted in FIG. 14 at four portions A (base), B (lower middle—40 mm above base), C (upper middle—90 mm above base), and D (neck—150 mm above base). The preform samples taken from sections at the portions that were (i) not subjected to annealing (FIG. 15A), (ii) subjected to annealing and blow forming with 4% expansion (FIG. 16A), (iii) subjected to annealing and blow forming with 18% expansion (FIG. 17A), and (iv) subjected to annealing and die necking (FIG. 18A). Each of the photographs and analysis images 15A/B, 16A/B, 17A/B, and 18A/B have the same scale. The analysis images in FIGS. 15B-18B were obtained with ImageJ software processing that extracts grain outlines from the microstructure photographs in order to conduct quantitative analysis of grain size and aspect ratio.
[0122] FIGS. 15A and 15B (collectively FIG. 15) are an illustrative photograph and analysis image, respectively, that illustrate the grain structure at a base (FIG. 14, portion A) of a shaped metal container. The base, in this embodiment, is not annealed or blow formed and has a grain structure that flat, “pancake”-like, elongated, and aligned in its orientation. FIG. 15B is an analysis image in which the grain structure is outlined to provide for computer analysis to determine an average aspect ratio of the grains in the portion being sampled. The grains extend two-directionally across the base. In this embodiment, the grain has an average width of 55.70 microns, height of 7.45 microns, and aspect ratio of 7.03. It is noted that the algorithm is to calculate the aspect ratio of each individual grain first, then average over the aspect ratios of all the grains calculated. Therefore the average aspect ratio is not simply average width divided by the average height.
[0123] FIGS. 16A and 16B (collectively FIG. 16) are an illustrative photograph and analysis image, respectively, that illustrate the grain structure at a lower middle section (FIG. 14, portion B) of a shaped metal container. The grains at this section are annealed and expanded 4%. The grains are shown to be randomized (i.e., no longer “pancake”-like and aligned in orientation). In this embodiment, the grain has an average width of 23.91 microns, average height of 16.70 microns, and average aspect ratio of 1.54.
[0124] FIGS. 17A and 17B (collectively FIG. 17) are an illustrative photograph and analysis image, respectively, that illustrate the grain structure at an upper middle section (FIG. 14, portion C) of a shaped metal container. The grains at this section are annealed and expanded 18%. The grains are shown to be randomized (i.e., no longer “pancake”-like and aligned in orientation). In this embodiment, the grain has an average width of 25.55 microns, average height of 15.89 microns, and average aspect ratio of 1.71.
[0125] FIGS. 18A and 18B (collectively FIG. 18) are an illustrative photograph and analysis image, respectively, that illustrate the grain structure at a neck section (FIG. 14, region D) of a shaped metal container. The grains at this section are annealed die necked. The grains are shown to be randomized (i.e., no longer “pancake”-like and aligned in orientation). In this embodiment, the grain has an average width of 18.64 microns, average height of 14.10 microns, and average aspect ratio of 1.36.
[0126] The effects in relation to the change in grain structure may be explained in that the flat, “pancake”-like grain structure is asymmetrical and two-directional, so that the properties are different in both directions. The rounded grain structure is symmetrical and omni-directional, so that the properties are more uniform in any direction. The flat, “pancake”-like grains extend parallel to the rolling direction, and are therefore prone to splitting during necking or flanging. Moreover, the structure includes undue stress. The rounded grain structure is far less prone to splitting during necking and flanging. Because the grains extend more omni-directional, the structure includes less stresses and is thus more formable.
[0127] As indicated hereinbefore, in the making of a shaped metal container provided with a container bottom section, container middle section, and container top section that have different diameters larger, equal, and smaller than the preform diameter Dc, conflicting shape making conditions exist. Because in the making of such shaped metal container the sections or section parts having a diameter larger than the diameter Dc should be less hard such as a lower yield strength, and a high ductility and elongation at break, whereas sections or section parts that have a diameter smaller than Dc and produced by necking use a relatively high strength or hardness. Above that, situations have been described in which the preforms may be first subjected to necking and subsequently other parts subjected to blow forming. These conflicts of manufacturing processes may be overcome or surpassed by utilizing the principles of the present invention inclusive of inward shaping and outward shaping, where the outward shaping is performed after annealing treatment to enable greater expansion of the annealed preform.
[0128] It will be obvious to the skilled person that the method for making the shaped metal container makes use of various techniques already existing in the container making process. Accordingly, the processes described herein can be easily incorporated in existing container producing lines.
[0129] The annealing process provides for an elegant form of outwardly shaping, particularly by to incorporate aesthetic and ornamental designs, such as logos, may be carried out in an oven that is relatively slow or by induction that is relatively fast. Induction annealing or annealing provides the further advantage of locally fast annealing or annealing a section or part of the section of the preform. In addition, it is possible to first have the preform annealed in an oven as a whole, and after a blow forming step, a further annealing process may be carried out in a particular section or section part where after that part is further subjected to a blow forming step as desired or dictated by the desired shape or form of the shaped metal container. The annealing results in the reduction of the hardness, in particular of the yield strength, whereas the elongation at break is increased, such as to 10-25%, more particularly 15-20%, such as 18-20%.
[0130] The shaped metal container is generally produced from a metal, such as aluminum or steel, or from alloys, which may have a particular temper. It is also possible to use combinations of metal with plastics and with glass.
[0131] Finally, although not described in detail, in making the shaped metal container, it is also possible to make a shaped metal container that does not have a circular cross-section, but may have a non-circular cross section, such as an oval, ellipse, or any other geometrical or non-geometrical shaped cross-section.
[0132] Although particular embodiments of the present invention have been explained in detail, it should be understood that various changes, substitutions, and alterations can be made to such embodiments without departing from the scope of the present invention as defined by the following claims.
