WO2023288126A1

WO2023288126A1 - Article and method of manufacturing cookware

Info

Publication number: WO2023288126A1
Application number: PCT/US2022/037452
Authority: WO
Inventors: Stanley Kin Sui Cheng
Original assignee: Meyer Intellectual Properties Limited
Priority date: 2021-07-16
Filing date: 2022-07-18
Publication date: 2023-01-19

Abstract

An article of cookware is formed from a planar sheet of a relatively pure alloy or pure metal by a process of deep drawing that work hardens the sidewalls, and is combined with a process for one of work hardening or reinforcing the bottom of the cookware article. The planar sheet preferably has low surface energy coating to form the inner surface of the article cookware, and may optionally have an outer surface covered by another coating. The work hardening of the bottom of the cookware, that is not deformed in the drawing process, can be accomplished by a process of forming irregular surfaces, such as one of ridges and channels in the bottom by additional deformations, and/or embedding a metal plate(s) or mesh within the exterior bottom surface.

Description

ARTICLE AND METHOD OF MANUFACTURING

COOKWARE

Background [0001] This disclosure relates to cookware constructed of metal, and methods of manufacturing the same.

[0002] It is desirable that metal cookware has a high thermal conductivity to rapidly heat, and to provide a uniformly hot cooking surface.

[0003] However, most metals used in forming cookware are by necessity alloys to provide strength and resist deformation from either thermal distortion or normal wear and tear.

[0004] Alloying metals (i.e., providing mixtures of metal atoms), while useful in improving strength, decreases thermal conductivity.

[0005] Pure metals and relatively pure alloyed metals (i.e., with a low percentage of the alloying element or elements), have higher thermal conductivity.

[0006] It would be desirable to form cookware from relatively pure metals, yet also have the resultant cookware be strong enough to resist thermal distortion and damage, dings, or crushing from normal use.

[0007] The above and other objects, effects, features, and advantages of the present disclosure will become more apparent from the following description of the embodiments thereof taken in conjunction with the accompanying drawings. Summary

[0008] In the present disclosure, the first object may be achieved by providing a method of forming a cookware article, the method comprising the steps of providing a planar disk of an essentially pure metal, deep drawing the disk to form a vessel having a bottom surrounded by one or more substantially upright sidewalls that terminate in a rim, in which the sidewalls are work hardened in the deep drawing process to increase at least one of the stiffness and yield strength (i.e., increase the stiffness, increase the yield strength, or increase both the stiffness and the yield strength) of the metal of the sidewalls relative to the planar disk, and deforming an exterior of said bottom to provide an irregular surface so as to work harden the bottom to increase at least one of the stiffness and yield strength (i.e., increase the stiffness, increase the yield strength, or increase both the stiffness and the yield strength) of the bottom.

[0009] A second aspect of the disclosure is characterized by such a method of forming a cookware article wherein the planar disk has an upper surface covered by at least one layer of an organic coating with a low surface energy, in which said upper surface forms an interior portion of the upright sidewalls and bottom.

[0010] Another aspect of the disclosure is characterized by any such method of forming a cookware article wherein the planar disk has a lower surface covered by at least one layer of an organic coating that is plastic deformable and heat resistant to at least about 400°C, in which said lower surface forms an exterior portion of the upright sidewalls and bottom.

[0011] Another aspect of the disclosure is characterized by an article of cookware comprising a bottom having an interior surface covered by a low surface energy coating, one or more substantially upright sidewalls that surround and are coupled to the bottom and that extend upward to terminate at a rim, the sidewalls having an interior surface, wherein the bottom and sidewalls of the cookware article are formed from at least one of aluminum and an alloy of aluminum that is at least about 99% aluminum by weight (i.e., formed from aluminum, formed from the alloy of aluminum, or formed from both the aluminum and the alloy of aluminum), a perforated member extending across at least a part of the exterior bottom of the cookware article in which the at least one of the aluminum and the alloy of aluminum extends at least partially through the perforations thereof in which the perforated member is formed of a metal that is substantially harder than aluminum.

[0012] Another aspect of the disclosure is characterized by such an article of cookware wherein the perforated member is formed of steel.

[0013] Another aspect of the disclosure is characterized by any such article of cookware wherein the steel is ferromagnetic stainless steel.

[0014] Another aspect of the disclosure is characterized by any such article of cookware wherein the perforated member has a convoluted structure with alternating channels that receive the at least one of the aluminum and the alloy of aluminum in which the perforations are between the channels and the at least one of the aluminum and the alloy of aluminum flows at least partially through the perforations but does not flow substantially beyond the perforations.

[0015] Another aspect of the disclosure is characterized by any such article of cookware wherein the channels are arranged as concentric annuli.

[0016] Another aspect of the disclosure is characterized by any such article of cookware wherein the channels are arranged radially.

[0017] Another aspect of the disclosure is characterized by an article of cookware comprising a bottom having an interior surface covered by a low surface energy coating, one or more substantially upright sidewalls that surround and are coupled to the bottom and that extend upward to terminate at a rim, the sidewalls having an interior surface, wherein the bottom and sidewalls of the cookware article are formed from at least one of aluminum and an alloy of aluminum that is at least about 99% aluminum by weight (i.e., formed from aluminum, formed from the alloy of aluminum, or formed from both the aluminum and the alloy of aluminum), a reinforcing member extending across at least a portion of the exterior bottom of the cookware article being coupled to at least a portion of the at least one of the aluminum and the alloy of aluminum that is plastic deformed.

[0018] The above and other objects, effects, features, and advantages of the present disclosure will become more apparent from the following description of the embodiments thereof taken in conjunction with the accompanying drawings.

Brief Description of Drawings

[0019] FIGS. 1A-C are respectively a cross-sectional elevation view of the disk used to form an embodiment of the cookware article, an expanded view of the portion from FIG. 1 A that is surrounded by a broken line boundary, and a plan view of the disk.

[0020] FIG. 2 is a flowchart of a first embodiment of a process for forming an embodiment of the cookware article.

[0021] FIG. 3 A is a cross-sectional elevation view of a cookware article formed with the process of FIG. 2, whereas FIG. 3B is a bottom plan view of the cookware article.

[0022] FIG. 4 is a flowchart of another embodiment of a process for forming an embodiment of the cookware article.

[0023] FIG. 5A is a cross-sectional elevation view of an embodiment of a cookware article formed with the process of FIG. 4, whereas FIG. 5B is a cross-sectional elevation view after the first step and before the final step of the process of FIG. 4.

[0024] FIG. 6A is a cross-sectional elevation view of another embodiment of a cookware article formed with the process of FIG. 4, whereas FIG. 6B is a cross-sectional elevation view after the first step and before the final step of the process of FIG. 4.

[0025] FIG. 7A is a cross-sectional elevation view of another embodiment of a cookware article formed with the process of FIG. 4, whereas FIG. 7B is a bottom plan view of the cookware article of FIG. 7A, and FIG. 7C is an expanded view of the portion of FIG. 7A that is within the broken line boundary.

[0026] FIG. 8A is a cross-sectional elevation view of another embodiment of a cookware article formed with the process of FIG. 4, whereas FIG. 8B is a bottom plan view of the cookware article of FIG. 8A, and FIG. 8C is an expanded view of the portion of FIG. 8A that is within the broken line boundary.

[0027] FIG. 9 is a flowchart of another embodiment of a process for forming an embodiment of the cookware article.

[0028] FIG. 10A is a cross-sectional elevation view of another embodiment of a cookware article formed with the process of FIG. 9, whereas FIG. 10B is a bottom plan view of the cookware article of FIG. 10A.

Detailed Description

[0029] Referring to FIGS. 1A through 10B, wherein like reference numerals refer to like components in the various views, there is illustrated therein a new and improved cookware article, generally denominated 100 herein.

[0030] In accordance with the present disclosure, the cookware article 100 comprises a bottom 115 having an interior surface and an exterior surface opposite the interior surface, as well as sidewall(s) 116 extending upward and surrounding the perimeter of the interior surface to terminate at a rim 117 of the cookware article 100, an example of which is illustrated in FIG. 3A. [0031] Cookware article 100 in the most preferred embodiments is fabricated from a substantially planar sheet of metal with a relatively high thermal conductivity due to a relatively high level of purity. In the case of aluminum alloys, when the alloy is about 99.5 weight percent pure aluminum, the thermal conductivity is 30 to 40% greater than alloys containing about 4 to 5% other metals. These other metals are typically added to provide improvements in properties such as strength, chemical resistance, hardness, or modulus. For forming cookware articles with circular symmetry, the planar sheet is preferably disk-shaped, as illustrated in FIG. 1C. A first outer surface of the aluminum sheet or disk 101 may be covered by one or more layers of a deformable nonstick coating layer 103 (as is illustrated in FIG. IB) that may comprise hard inorganic particles dispersed within a polymeric matrix to provide mechanical reinforcement, such as silica, alumina, Titania, silicon carbide, and diamond dust or particulate, as well as flakes such as mica mineral particles. The polymeric matrix is preferably a low surface energy polymer such as a fluoropolymer, but is also optionally a silicone or fluoro silicone, and copolymers thereof, and may contain a resin that reacts or fuses to form a matrix or bi-continuous phase to lock the low energy polymer particles or phase in place.

[0032] The second outer surface of the aluminum sheet or disk 101, which is opposing the first outer surface is also preferably covered by one or more layers of a deformable organic coating 104, which is preferably a silicone polyester coating to provide heat resistance.

[0033] Various U.S. patents teach compositions of matter and methods of applying organic based and non-stick coatings to cookware vessels. These include U.S. Patent No. 3,986,993 to Vassiliou (issued 10-19- 1976); U.S. Patent No. 4,118,537 to Vary, et al. (issued 10-03-1978); U.S. Patent No. 4,321,177 to Wilkinson (issued 03-23-1982); U.S. Patent No. 5,691,067 to Patel (issued 10- 25-1997); and U.S. Patent No. 6,133,359 to Bate, et al. (issued 10-17-2000), all of which are incorporated herein by reference in their entirety. [0034] Such non-stick coatings, including fluoropolymer coatings are generally applied as a fluid containing fusible particles of fluoropolymer resin and a carrier vehicle, along with additives (such as agents and surfactants), as well as organic particles for reinforcement. The fluid is applied to the outer layer by various methods, such as spray coating, curtain coating, or roller coating. The sheet is heated to evaporate the carrier vehicle, after which the sheet is heated to a high temperature, typically about 800°F, for at least about 10 to 40 minutes to fuse the particles of polymer resin together, and essentially what is a reactive sintering process to form a cohesive and adherent coating on the outer surface.

[0035] It is particularly economically efficient to use roller coating to cover the aluminum sheet or disk 101 with the fluoropolymer coating. However, a limitation of this method is that the sintering process may fuse the binder and/or the polymer resin particles of the nonstick coating, and/or the high temperature may cause relatively pure aluminum alloys to become excessively soft. Additionally, it may be more difficult to spray one or more coatings to cover the cookware after it is formed.

[0036] Referring to FIG. 1C, the disk 101 has a central interior region 105 surrounded by an outer annulus 106 that terminates at an outer perimeter 107. In step 1120 of the process 1000 or 1000' of FIGS. 2 and 4, as one deep draws the disk 101, the outer annulus 106 will be deformed biaxially to form the sidewall(s) 116 of the cookware article 100; however, the central interior region 105, which forms the bottom 115 of the cookware article 100, will not be deformed, in some embodiments.

[0037] The harder and stronger aluminum alloys used to form cookware have a lower thermal conductivity than the more pure alloys. In the various embodiments of the disclosure, the aluminum sheet is a fairly pure alloy with high thermal conductivity, and additional processes are deployed to strengthen or work harden the bottom of the cookware article. The more pure alloys anneal and soften more readily after work hardening, and are generally not used when the article can be exposed to higher temperatures. Ideally, the aluminum sheet has less than about 1 weight % alloyed metal, and more preferably less than about 0.5 weight % of other metals, such that it is essentially close to thermal conductivity of pure aluminum.

[0038] Although rolled sheets of aluminum and aluminum alloys (including alloys with about 0.5 to 1% admixtures of other metals), are optionally work hardened during a cold rolling process, to increase the hardness and yield strength as well as the modulus, they may also be annealed to improve ductility for deep forming into vessels. Annealing aluminum at temperatures of about 700 to 800°F will cause the metal grains to enlarge, thereby softening the aluminum. Hot rolling results in less work hardening due to the simultaneous annealing and less resistance to plastic flow.

[0039] Hence, in the process 1000 of FIG. 2, by deforming an exterior of said bottom 115 to provide an irregular surface, post annealing work hardening may be provided to the bottom 115 to increase at least one of the stiffness and yield strength (i.e., increase the stiffness, increase the yield strength, or increase both the stiffness and the yield strength) to make the cookware article 100 more durable.

[0040] Accordingly, in the first embodiment of the process 1000 of FIG. 2, the exterior bottom 115b (an example of which is illustrated in FIG. 3B) is deformed by forming a pattern of ribs 119 that provide an irregular surface that is thicker to increase stiffness from the ribs themselves, as well as to increase the modulus of the aluminum by work hardening. A non-limiting example of such an irregular surface is the ribs 119 as illustrated in FIG. 3A- B, where the ribs 119 extend radially from about the geometric center of the bottom of the cookware article 100. The exterior bottom 115b of the cookware article 100 between the ribs 119 is designated as reference number 118. [0041] In one embodiment, the deep drawing process may include forming a convoluted surface with ridges or ribs that add strength. The forming of the ridges or ribs is a deformation process that also results in some work hardening. The ridges or ribs may be in circular or linear patterns. Between such ribs (or other raised regions) may be recessed channels. The ribs (or other raised regions) may be continuous across the exterior bottom or discontinuous, and the recessed channels may be continuous across the exterior bottom or discontinuous.

[0042] However, because cookware made of relatively pure alloys can be overheated past a temperature at which annealing occurs (causing the bottom to re-soften and become weak), a second embodiment corresponding to the flow chart of FIG. 4 is more preferred, in some embodiments. It should be noted, it is very difficult to heat the sidewall(s) of cookware above the annealing temperature, as they radiate heat to the environment and are most distal from the flame or other hear source.

[0043] In the process 1000' of FIG. 4, the first step 1100 is providing the planar disk 101 of a relatively pure alloy with high thermal conductivity.

[0044] As in the process of FIG. 2, the subsequent step 1120 of FIG. 4 is to deep draw the disk 101 to work harden the sidewalls 116. In this second embodiment of the process, one or more generally near planar member(s) 113 (an example of which is illustrated in FIG. 5B) are attached or inserted into the exterior bottom 115b. The planar member(s) 113 may be attached/inserted via various known methods. Non-limiting examples of such methods are included in at least the following, each of which is incorporated herein by reference in its entirety: (1) U.S. Patent Publication No. 2008/003-5139 A1 (Moran, V. Published February 14, 20080), which discloses a process for attaching a perforated plate with annular symmetry to the bottom of cookware article; (2) U.S. Patent No. 4,544,818, which discloses a method of attaching a perforated plate of ferromagnetic metal to the bottom of cookware article; and (3) U.S. Patent No. 5, 430, 928 (Fleming, D. Issue July 11, 1995), which discloses a method of attaching a greater perforated plate to the bottom of the cookware vessel.

[0045] While the perforated member 113 is preferably continuous and the holes are dispersed there within, an alternative is to insert what is essentially the negative discontinuous generally planar members into the bottom of the cookware vessel in which each discontinuous member is optionally one of perforated or has upward extending barbs to dig in and grasp the soft aluminum in the base. Non-limiting examples of such methods are included in at least the following, each of which is incorporated herein by reference in its entirety: (1) U.S. Patent number 5,487,329 (Fissler H, issued January 30, 1996), which discloses a method of inserting insets composed of austenitic sheet steel into the bottom of the pot for electromagnetic conduct heating; (2) U.S. Patent No. 5,506,062 (Flamming, D. Issued April 9, 1996), which also discloses a method of drop forging or stamping to embed a perforated sheet or grid into the base of the cookware vessel; (3) U.S. Patent No. 5, 694,674 with the same inventor that issued December 9, 1997, which teaches a variant on such method; (4) U.S. Patent No. 5,532,461 (Cmmmenauer, M. Issued July 2, 1996), which discloses a method of inserting a ferromagnetic plate with radial slots into the bottom of a cooking utensil; and (5) U.S. Patent No.

6,702, 140B1 (Sollo, G. Issued March 9, 2004) and U.S. Patent No. 6,782,599 B1 (Soil, G. issued August 31, 2004), both of which disclose cookware articles and methods of forming the same in which a plate member is attached to the bottom of the cookware vessel, with the upward extending projections or sharp points in the plate, and where the points penetrate into the metal, but ultimately form laterally locking the plate in place.

[0046] FIG. 4 also illustrates several optional steps by a broken line boundary in which any or all of optional steps 1130, 1140 and 1150 may be included in the process. The planar member 113 (an example of which is illustrated in FIG. 5B) when at least partially perforated or when it has recess grooves facing the exterior bottom of aluminum, allows the softer aluminum from the bottom 115b to flow into the pores or perforations 113p in the planar member 113 during the insertion step. This deformation work hardens the bottom 115. Preferably the perforated planar member 113 is formed of a metal or alloy significantly harder than the relatively pure aluminum, such as stainless steel and more preferably ferromagnetic stainless steel to provide the capability of heating the bottom of the cookware article 100 by an induction range. In some embodiments, such a steel disk will maintain its hardness and reinforce the cookware article 100 even if the cookware article is overheated by the consumer, which could result in annealing and softening of the aluminum alloy that forms the exterior bottom 115.

[0047] The planar member 113 can assume various forms of shape, some of which may be more preferable than others. In some embodiments, the softness of the annealed aluminum in the bottom 115 is actually an advantage in that less force or greater plastic flow of the metal into the pores, perforations 113p, or recessed grooves in the planar member 113 occurs. The embodiment of FIGS. 5 A and 5B illustrates the perforated member 113 as being planar and having perforations 113p with sidewalls that are orthogonal to the top and bottom planes of the member.

[0048] FIGS. 6A and 6B illustrate a more preferred embodiment in which the perforated member 113 has a convoluted shape with alternating high and low surfaces, and which the perforations 113p are in the lower regions 1131 (an example of which is illustrated in FIG. 7C), that are between the higher or deeper channels or recessed grooves 113c.

[0049] Furthermore, the partially perforated disk or mesh of a stronger metal 113, such as stainless steel, copper or alloys thereof, are embedded into the outer surface 115b of the center of the disk 101 either before, during, or after the deep drawing process, such as in a secondary process in which the member 113 is held in a die with space for the aluminum to flow into the perforations. [0050] It should be appreciated that the perforated member 113 can also be formed with radial recessed channels to assume the shape of the bottom of the cookware vessel as illustrated in FIGS. 3 A and 3B.

[0051] It is also preferable that the entire outer surface of the plate or disk 101 is covered by the deformable coating, such as a silicone polyester coating, and during this embedding process both this organic coating is deformed as well as the outer surface of the disk to flow into the apertures within the disk or member 113, or wire meshes or meshes used as the member 113.

[0052] FIGS. 7A-7C illustrate an embodiment where the channels 113c have circular symmetry, that are arranged as concentric annuli.

[0053] In the embodiment shown in FIGS. 8 A and 8B, the member 113 has a perforation 113p between thick ridges 113r, which provide rigidity. The region 1131 with the perforations 113p is relatively thin compared to the ridges, limiting the need for the aluminum to flow very far through them. Ideally, the aluminum may flow into the gap or recessed channels 113g between ridges 113r, and beyond the boundary of the perforations 113p, to lock the member 113 in place.

[0054] FIGS. 9-10B illustrate an additional embodiment of the disclosure in which the bottom the cookware vessel is planarized on the bottom at least partially after forming. The planarizing would remove any exterior coating on the original planar disk. The planarizing may be useful if the irregular shape to work harden the bottom has a shape not amenable to the attachment of the plate or disk 113.

[0055] As a nonlimiting example of such an embodiment, the higher thermal conductivity aluminum planar disk may have a thickness of about 3 mm. During the forming process, grooves may be formed with a depth of about 0.7 - 0.8 mm. As the region adjacent to these groove is likely to have some curvature, it would be removed in the planarized process such as by machining, grinding, and/or polishing.

[0056] In such an example, thickness of about 0.2 mm may be removed from the exterior bottom. [0057] It should be appreciated that the description and drawings are not intended to exclude the possibility that the interior bottom surface of the cookware has an irregular shape from the deformation steps to promote work hardening of the thin aluminum layer that is essentially close to pure aluminum in its thermal conductivity. [0058] While the disclosure has been described in connection with a preferred embodiment, it is not intended to limit the scope of the disclosure to the particular form set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be within the spirit and scope of the disclosure as defined by the appended claims.

Claims

CLAIMS What is claimed is:

1. A method of forming a cookware article, the method comprising the steps of: a. providing a planar disk of an essentially pure metal, b. deep drawing the disk to form a vessel having a bottom surrounded by one or more substantially upright sidewalls that terminate in a rim, in which the sidewalls are work hardened in the deep drawing process to increase at least one of the stiffness and yield strength of the metal of the sidewalls relative to the planar disk, and c. deforming an exterior of said bottom to provide an irregular surface so as to work harden the bottom to increase at least one of the stiffness and yield strength of the bottom.

2. The method of forming a cookware article according to claim 1, wherein the planar disk has an upper surface covered by at least one layer of an organic coating with a low surface energy, wherein said upper surface forms an interior portion of the upright sidewalls and bottom.

3. The method of forming a cookware article according to claim 1, wherein the planar disk has a lower surface covered by at least one layer of an organic coating that is plastic deformable and heat resistant to at least about 400°C, wherein said lower surface forms an exterior portion of the upright sidewalls and bottom.

4. The method of forming a cookware article according to claim 1, wherein the cookware is formed from one of aluminum and an alloy of aluminum containing less than 1 weight % admixture of other metals.

5. The method of forming a cookware article according to claim 1, wherein the cookware is formed from one of aluminum and an alloy of aluminum containing less than 0.5 weight % admixture of other metals.

6. The method of forming a cookware article according to claim 1, wherein the step of deforming an exterior of said bottom to provide an irregular surface so as to work harden the bottom to increase at least one of the stiffness and yield strength of the bottom results in a pattern of ridges.

7. The method of forming a cookware article according to claim 1, wherein the step of deforming an exterior of said bottom to provide an irregular surface so as to work harden the bottom to increase at least one of the stiffness and yield strength of the bottom forms a series of raised ridges on the exterior bottom that are separated by a recessed channel.

8. The method of forming a cookware article according to claim 7, further comprising a step of removing at least a portion of the raised ridges to form a planarized surface thereon.

9. The method of forming a cookware article according to claim 7, wherein the cookware is formed from one of aluminum and an alloy of aluminum containing less than 1 weight % admixture of other metals.

10. The method of forming a cookware article according to claim 7, wherein the cookware is formed from one of aluminum and an alloy of aluminum containing less than 0.5 weight % admixture of other metals.

11. An article of cookware comprising: a. a bottom having an interior surface covered by a low surface energy coating, b. one or more substantially upright sidewalls that surround and are coupled to the bottom and extend upward to terminate at a rim, the sidewalls having an interior surface, c. wherein the bottom and the sidewalls of the cookware article are formed from at least one of aluminum and an alloy of aluminum that is at least about 99% aluminum by weight, and d. a perforated member extending across at least a part of the exterior bottom of the cookware article, wherein the at least one of aluminum and the alloy of aluminum extends at least partially through perforations in the perforated member, wherein the perforated member is formed of a metal that is substantially harder than aluminum.

12. The cookware article according to claim 11, wherein the perforated member is formed of steel.

13. The cookware article according to claim 12, wherein the steel is ferromagnetic stainless steel.

14. The cookware article according to claim 11, wherein the perforated member has a convoluted structure with alternating channels that receive the at least one of aluminum and the alloy of aluminum, wherein the perforations are between the channels and the at least one of aluminum and the alloy of aluminum flows at least partially through the perforations but does not flow substantially beyond the perforations.

15. The cookware article according to claim 14, wherein the channels are arranged as concentric annuli.

16. The cookware article according to claim 14, wherein the channels are arranged radially.

17. An article of cookware comprising: a. a bottom having an interior surface covered by a low surface energy coating, b. one or more substantially upright sidewalls that surround and are coupled to the bottom and that extend upward to terminate at a rim, the sidewalls having an interior surface, c. wherein the bottom and the sidewalls of the cookware article are formed from at least one of aluminum and an alloy of aluminum that is at least about 99% aluminum by weight, and d. a reinforcing member extending across at least a portion of the exterior bottom of the cookware article and being coupled to at least a portion of the at least one of the aluminum and the alloy of aluminum that is plastic deformed.

18. The article of cookware according to claim 17, wherein the reinforcing member has a plurality of holes, a plurality of recesses, or a plurality of holes and recesses, wherein the portion of the bottom that enters the plurality of holes, the plurality of recesses, or the plurality of holes and recesses is work hardened.

19. The article of cookware according to claim 17, wherein the bottom and the sidewalls of the cookware article are formed from at least one of aluminum and an alloy of aluminum that is at least about 99.5 % aluminum by weight.

20. The article of cookware according to claim 19, wherein the reinforcing member has a plurality of holes, a plurality of recesses, or a plurality of holes and recesses, wherein the portion of the bottom that enters the plurality of holes, the plurality of recesses, or the plurality of holes and recesses is work hardened.