MÉTODO PARA PRODUZIR UMA FOLHA DE LATA DE ALUMÍNIO

Abstract

METHOD AND INSTALLATION FOR PRODUCING ALUMINUM TIN SHEET. A method for producing aluminum tin sheet comprises the following steps: providing a body made of an aluminum alloy of type AA3004, AA3104 or other aluminum alloy suitable for making an aluminum tin sheet; heating the body to a homogenization temperature; hot rolling said body in a hot rolling mill to produce a hot-rolled sheet, said hot-rolled sheet exiting the hot rolling mill at a hot rolling exit temperature with a hot rolling mill exit gauge, wherein the hot rolling exit temperature is selected to substantially avoid recrystallization of the hot-rolled sheet; cold rolling the hot-rolled sheet in a cold rolling mill to apply a cold reduction to produce a cold-rolled sheet with a cold rolling mill exit gauge smaller than the hot rolling mill exit gauge;Annealing the cold-rolled sheet in a selected intermediate temperature range to allow recrystallization of the cold-rolled sheet to obtain a recrystallized annealed sheet; cold rolling the recrystallized annealed sheet to apply a cold reduction to produce a cold-rolled sheet with a final gauge.

Description

1 / 25 METHOD FOR PRODUCING AN ALUMINUM CAN SHEET TECHNICAL FIELD AND STATE OF THE ART

[001] The present invention relates to a method for producing aluminum tin foil and to an installation configured to carry out the method.

[002] When aluminum can sheet is formed into cup-shaped articles, a phenomenon known as earing usually occurs to some extent. Earing can be observed as a wave-like appearance around the top edge of the formed cup. The protruding wave-like portions, also known as “ears,” are formed during the deep-drawing step in cup manufacturing and represent an undesirable feature of the article. In aluminum can body stock (CBS), the cup is subsequently ironed in several rings which can accentuate the wavy ears. High earing can create transportation problems with the cup, as well as insufficient trimming after ironing, clipped ears, and trimmer jams. These artifacts are undesirable in aluminum can manufacturing. Thus, it is desirable to minimize earing to avoid these problems and increase cup quality.

[003] It is known that can body stock material, such as AA3004, AA3104 or other aluminum alloy, is basically suitable for manufacturing aluminum tin foil with low earing characteristics, provided that a suitable manufacturing process can be established.

[004] There is a well-known process established in the aluminum industry for the production of aluminum strip. Petition 870250108948, dated 11 / 27 / 2025, page 11 / 44 2 / 25 suitable for can body stock. This process involves hot rolling an aluminum ingot through a roughing mill and then through a multi-support hot mill, usually exiting at high temperature to ensure a fully recrystallized material obtained through a self-annealing process. This well-known method produces a final product with low earring and desirable mechanical characteristics. However, the installation and operation of such a continuous hot mill requires a large capital expenditure.

[005] Modifications have been proposed in the past to produce tin foil with commercially acceptable ear-like characteristics from a single-support reversible rolling mill (see, for example, US 5,362,340 and US 5,362,341). According to the method in US 5,362,340, an aluminum alloy ingot is supplied and heated to a temperature between about 527 °C and 571 °C. The ingot is then hot-rolled in a single-support reversible hot rolling mill to produce an intermediate gauge foil. The intermediate gauge foil, which is either self-annealed or discontinuously annealed, is then cold-rolled to produce a final gauge aluminum tin foil with low ear-like characteristics. Low-temperature relative homogenization (527°C to 571°C) is applied to prevent uncontrolled recrystallization during hot rolling in the single-support reversible mill.

[006] US patent application 2002 / 0062889 A1 describes a process and an installation for the production of strips of Petition 870250108948, dated 11 / 27 / 2025, page 12 / 44 3 / 25 hot-rolled aluminum for can manufacturing. The installation includes a reverse roughing stage for the feed material, which is used hot, followed by the finishing roll of the strip, which is followed by heat treatment of the rolled strip into coils. During the final finishing roll passes, recrystallization in the rolled material is suppressed through controlled temperature management of the hot strip. In this design, the temperature is maintained in the non-critical temperature range of 260°C to 280°C to prevent recrystallization. Recrystallization only occurs outside the rolling mill. For this, the hot-rolled material is transferred to a continuous furnace immediately after the finishing roll.Direct transfer offers the advantage that a furnace used for recrystallization only needs to apply a relatively small temperature difference (e.g., around 40°C - 60°C) between the rolling temperature and the recrystallization temperature, thus achieving a favorable energy balance.

[007] The international patent application published as WO 2015 / 140833 A1 describes aluminum alloy sheets with a low ingot ratio suitable for making aluminum can bodies. The alloys mentioned for this purpose include A3004 and A3104 type alloys. A preferred process includes the steps of ingot casting, ingot homogenization, hot rolling, primary cold rolling, intermediate annealing, and secondary cold rolling. The hot rolling step is divided into two separate steps, namely, “hot roughing rolling step” and “finishing rolling step”. Petition 870250108948, dated 11 / 27 / 2025, page 13 / 44 4 / 25 hot”. In the hot finishing lamination stage, the final temperature is preferably between 330°C and 380°C. It is observed that the driving force of recrystallization is insufficient if the final temperature is below 330°C. SUMMARY OF THE INVENTION

[008] It is an object of the invention to provide a method and an installation for the production of aluminum foil suitable for the manufacture of aluminum cans, wherein the aluminum foil exhibits favorable ear-forming characteristics after a deep drawing step and also allows the production of stable cans with thin wall thickness.

[009] This objective is solved by a method comprising the features of claim 1 and an installation comprising the features of claim 9. Preferred embodiments are defined in the dependent claims.

[010] According to the method for producing aluminum tin foil, a body (also called an ingot) made of an aluminum alloy is provided. The aluminum alloy is selected so that it is suitable for making aluminum tin foil. Specifically, the aluminum alloy is of the type AA3004, AA3104 or another aluminum alloy suitable for making aluminum tin foil, such as the AA3204 alloy.

[011] Typical requirements for aluminum alloys suitable for making aluminum can foil are described, for example, in the article AlMn1Mg1 for Beverage Cans by J. Hirsch in: Virtual Fabrication of Aluminum Products Wiley-VCH 2006 (ISBN: 3-527-31363-X), chapter I4. In general, the material must provide an optimal combination Petition 870250108948, dated 11 / 27 / 2025, page 14 / 44 5 / 25 of sufficient strength and formability properties. For aluminum, strength is achieved by combining the addition of appropriate alloying elements for improved solid solution hardening (e.g., Mg and Mn) and pre-deformation (i.e., highly rolled sheet). Furthermore, the strength must remain sufficiently high even after subsequent paint baking cycles. Good formability is achieved by an optimal combination of alloying elements for good hardening (Mg) with some particle strengthening effects (Mn). The latter also maintains homogeneous deformation and provides a cleaning effect on the dies, preventing the formation of harmful oxides and seizing. Consequently, common aluminum alloys used for the production of tin bodies are AlMg1Mn1 = EN-AW 3004 and AlMg1Mn1(Cu) = EN-AW 3104, which best meet the strength and formability requirements of tin.

[012] In preferred embodiments, aluminum alloys are used which comprise the following chemical compositions (all figures in % by weight): about 0.05 - 0.60% by weight of Si (Silicon), preferably 0.15 - 0.5% by weight of Si; about 0.10 - 0.80% by weight of Fe (Iron), preferably 0.25 - 0.70% by weight of Fe; about 0.70 - 1.50% by weight of Mn (Manganese), preferably 0.80 - 1.40% by weight of Mn; about 0.80 - 1.50% by weight of Mg (Magnesium), preferably 0.90 - 1.30% by weight of Mg; about 0.05 - 0.25% by weight of Cu (Copper), preferably 0.10 - 0.25% by weight of Cu; up to 0.10% by weight of Ti (Titanium); up to 0.25% by weight of Zn (Zinc); and up to 0.15% by weight of impurities, preferably each one Petition 870250108948, dated 11 / 27 / 2025, page 15 / 44 6 / 25 of the impurities are less than 0.05% by weight; the remainder is Al (Aluminum).

[013] On the other hand, many aluminum alloys optimized for other purposes are not considered suitable for the manufacture of aluminum tin foil in the context of this application. These include, for example, 1XXX series alloys (essentially pure aluminum with a minimum content of 99% aluminum by weight), 2XXX series alloys alloyed with copper as the basic alloying element and capable of precipitation hardening with strengths comparable to steel, 4XXX series alloys with silicon as the basic alloying element, 5XXX series alloys alloyed with magnesium as the basic alloying element to offer excellent corrosion resistance, 6XXX series alloys alloyed with magnesium and silicon as basic alloying elements, 7XXX series alloys alloyed with zinc as the basic alloying element and capable of precipitation hardening, or the 8XXX series are alloyed with other elements not covered by other series, such as aluminum-lithium alloys.

[014] In general, the chemical compositions of AA3004, AA3104, AA3204 or other aluminum alloy suitable for making aluminum tin foil, as well as other aluminum alloys, are known to a person skilled in the art and are available, for example, in the Aluminum Association's Teal sheets.

[015] The body can be made of cast aluminum, which has subsequently been roughened to obtain a body suitable for further processing. The body is heated to a homogenization temperature. The main objective of this heating step is to homogenize the material. As Petition 870250108948, dated 11 / 27 / 2025, page 16 / 44 7 / 25 Homogenization temperatures can be in the range of about 500°C to about 600°C, for example, depending on the desired temperature for the next stage of the process. The body can be cooled to temperatures suitable for hot rolling.

[016] In a subsequent step, the body is hot-rolled in a hot rolling mill to produce a hot-rolled sheet. The hot-rolled sheet exiting the hot rolling mill exits the hot rolling mill at a hot rolling exit temperature. The hot rolling step produces a hot-rolled sheet with a hot rolling mill exit gauge, which is the thickness of the aluminum sheet after hot rolling. In the hot rolling step, temperature control is performed so that the hot rolling exit temperature is selected to substantially avoid recrystallization of the hot-rolled sheet. In the context of this application, the term recrystallization refers to a process by which deformed grains in a metallic body are replaced by a new set of grains that are essentially free of defects and nucleate and grow until the original grains have been completely consumed.Recrystallization reduces the strength and hardness of the material while increasing its ductility. In the present process, the hot rolling exit temperature is selected so that the sheet exiting the hot rolling mill exhibits a high density of defects, such as dislocations, etc., and high relative strength and hardness, while at the same time the ductility can be relatively low.

[017] As a guideline, the sheet substantially does not Petition 870250108948, dated 11 / 27 / 2025, p. 17 / 44 8 / 25 recrystallized after hot rolling can exhibit a tensile strength in the range of 190 MPa to 240 MPa, for example, while the same material would exhibit significantly lower tensile strength values ​​in a recrystallized state, for example, below about 150 MPa for the fully recrystallized material. Hardness values ​​can be determined by the Vickers hardness test and can then be expressed as the Vickers Hardness Number (HV) given in MPa (or N / mm2). Hardness can also be approximated from the ultimate tensile strength (UTS) values ​​by the well-known relationship for aluminum alloys UTS « 3*HV.

[018] In a subsequent step, the hot-rolled sheet is cold-rolled in a cold rolling mill. The aim of this step in the process is to achieve cold reduction, meaning that the gauge (or thickness) of the sheet is further reduced. Cold reduction is performed to produce a cold-rolled sheet with an exit gauge from the cold rolling mill that is smaller than the exit gauge from the hot rolling mill. Cold rolling follows the hot rolling step, after the sheet has cooled to temperatures of approximately 100°C or lower, for example, as low as 50°C to 60°C.

[019] The cold-rolled sheet (with the cold rolling mill exit gauge) is then transferred to a furnace to anneale the cold-rolled sheet in an intermediate temperature range with temperatures selected to allow recrystallization of the cold-rolled sheet. The annealing step results in a recrystallized sheet with the cold rolling mill exit gauge. The microstructure of Petition 870250108948, dated 11 / 27 / 2025, page 18 / 44 9 / 25 Recrystallized sheet typically exhibits a new set of relatively defect-free grains replacing the defective microstructure obtained by cold rolling. In some forms, tensile strength values ​​can range from 150 MPa to approximately 200 MPa, for example.

[020] In a subsequent step, the recrystallized sheet is cold rolled to apply a cold reduction to produce a cold rolled sheet with a final gauge, the final gauge being smaller than the output gauge of the cold rolling mill.

[021] In developing a new process, the inventors identified certain shortcomings of conventional methods and now propose a new way to produce aluminum tin foil economically, avoiding the shortcomings of the prior art. For example, studying the process described in US 5,362,340, it was found that the relatively low temperature homogenization treatment, in combination with the chemical composition of the aluminum alloy, could produce a strong cube texture after annealing (self-annealing or discontinuous annealing at the exit gauge of the hot rolling mill) which in some cases the cold rolling process following annealing cannot balance. This can result in aluminum tin foil with 0° / 90° earing or very low 45° earing.This ear-like characteristic can produce, during subsequent stamping and ironing processes, cans with ears compressed at 0° / 180° in relation to the rolling direction, as well as an increase in torn cans and poor performance for can manufacturers.

[022] In addition, some limitations of the laminator Petition 870250108948, dated 11 / 27 / 2025, page 19 / 44 Single-support reversible mills (10 / 25 mm) can cause problems in conventional processes. The hot mill exit gauge of a single-support reversible mill can typically vary up to values ​​of about 2.0 mm. Producing a smaller exit gauge from a single-support reversible mill is generally difficult and may not be feasible due to difficulties in controlling the crown, wedge, and sheet flatness. On the other hand, the trend among can manufacturers is to reduce the thickness of the can sheet, a trend also known as "down-gauging." If it is desired to produce a thinner end product with similar ingling and strength properties to the thicknesses usually used today, it is necessary to maintain the same total cold reduction applied to the material after intermediate annealing at the hot gauge thickness (self-annealing or discontinuous annealing).Achieving this goal would require reducing the output gauge of the hot rolling mill to values ​​significantly below 2 mm. The new process is able to substantially avoid these problems identified in conventional processes.

[023] The process according to the formulation of the invention above introduces a cold rolling step inserted between the previous hot rolling step and the subsequent intermediate annealing step. The new sequence of steps has at least two significant effects. A first effect can be understood by considering the final product, the other effect can be understood when considering the thermomechanical process itself.

[024] It was found that the final product presents Petition 870250108948, dated 11 / 27 / 2025, page 20 / 44 11 / 25 generally results in relatively low earling values. The resulting ears are most pronounced at approximately 45° (relative to the rolling direction). This earling orientation is generally preferable from the end customer's point of view, i.e., from the can manufacturer's point of view. The new method generally avoids or reduces high ears at 0° / 90° which are undesirable from the can manufacturer's point of view and which are very likely obtained with the process described in the prior art, such as US 5,362,340. From a metallurgical point of view, it is believed that cold reduction introduced after hot rolling and performed on an essentially non-recrystallized material can enhance the particle-stimulated nucleation (PSN) mechanism, which decreases the cube texture density that the material will have after intermediate annealing. The lower cube texture after annealing will result in an earling tending towards 45° instead of 0 / 90° for the final product.

[025] Regarding the second effect (on the capability of the thermomechanical process), it is observed that the final strength of the material and the scalloping is highly dependent on the amount of cold work after intermediate annealing at the hot gauge. For example, if, in a conventional process, a material with a final gauge of 0.26 mm is produced, the intermediate annealing can be carried out at approximately 2 mm gauge. Therefore, the total cold reduction is about 87%. Now consider a case where the end customer requests a final gauge of 0.24 mm. To produce the same scalloping and properties, it would be necessary to perform the intermediate annealing at approximately Petition 870250108948, dated 11 / 27 / 2025, page 21 / 44 12 / 25 1.85 mm. This relatively small thickness often cannot be satisfactorily achieved on a single-support reversible mill due to flatness and thickness range limitations. These limitations do not exist in the new method. Applying the new method allows a producer to produce thicker material from the hot mill (e.g., about 2.5 mm), perform a slight cold reduction to the required intermediate annealing gauge (1.85 mm in this hypothetical example), and anneale the sheet at the intermediate annealing to this gauge to make the material fully soft before being cold-rolled to the final gauge. In other words: Some limitations of using a single-support reversible mill as a hot mill no longer limit the capabilities of the overall process.If a single-support reversible rolling mill is used as a hot rolling mill, the method can also greatly increase the output of the single-support hot rolling mill, as it is producing thicker gauge.

[026] From another point of view, the advantages of the new process result, at least in part, from the fact that cold rolling is carried out in two separate stages, where the first cold rolling is carried out after hot rolling and before intermediate annealing (on non-recrystallized material) and the second cold rolling stage is carried out after recrystallization annealing (at intermediate temperature) on a material that is recrystallized. As a result, preferable ear strength and characteristics, as well as small final gauges, can be obtained even when rolling Petition 870250108948, dated 11 / 27 / 2025, page 22 / 44 Hot rolling (13 / 25) is performed using a single-support reversible rolling mill.

[027] Considering the advantages of the process described above, a single-support reversible mill is used as a hot mill in a preferred embodiment of the process and installation. While a tandem mill can be used instead of a single-support reversible mill to perform the hot rolling step, the use of a single-support reversible mill is typically much less expensive so that the final product can be made economically.

[028] In preferred embodiments, the single-support reversible rolling mill is used in two different modes of operation, wherein a first mode of operation includes one or more flat passes and a second mode of operation, used after the first mode of operation, includes one or more winding passes producing rolled sheet with the hot rolling mill exit gauge.

[029] The hot rolling stage should be carried out in such a way that recrystallization of the hot-rolled sheet is substantially avoided. In preferred processes, the hot rolling exit temperature is in the range of about 200°C to about 320°C, with preferred hot rolling exit temperatures being below 290°C. For aluminum alloys of the AA3004, AA3104 type or other aluminum alloys suitable for making aluminum tin foil, these temperatures are generally adequate to completely avoid recrystallization, which increases the advantages of the overall process. The correct temperatures to completely avoid recrystallization may be Petition 870250108948, dated 11 / 27 / 2025, p. 23 / 44 14 / 25 selected depending on the alloy type and may differ from alloy to alloy.

[030] When designing the cold rolling stage, it was found that a cold reduction between 5% and 70% is preferentially applied in the cold rolling mill that rolls the hot-rolled sheet. Cold reductions in this range are particularly capable of increasing particle-stimulated nucleation (PSN) which is believed to decrease the cube texture density in the annealed material.

[031] The cold rolling stage can be carried out at least in the last rolling passes, so that coils of cold-rolled sheet are obtained in the single-support reversible mill. In this case, it may be preferable that the annealing of the cold-rolled sheet be carried out in a batch furnace. Alternatively, a continuous furnace can be used for the annealing stage in the intermediate temperature range to obtain the recrystallized sheet.

[032] As the overall process allows for high degrees of overall reduction, a total reduction of more than 70% is applied to the aluminum foil between the hot rolling mill output gauge and the final gauge. The total reduction can be 80% or more or even 85% or more. This is partly due to the fact that cold rolling for gauge reduction is carried out in two stages instead of a single stage.

[033] The invention also relates to an installation for the production of aluminum tin foil, the installation being configured to carry out the method according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS Petition 870250108948, dated 11 / 27 / 2025, page 24 / 44 15 / 25

[034] Next, an embodiment of the invention will be described in detail with reference to the drawings.

[035] Fig. 1 shows a schematic drawing of a part of an installation configured to manufacture aluminum tin foil suitable for making cup-shaped articles; Fig. 2 shows a diagram illustrating the relationship between the degree of recrystallization of the sheet material after the initial hot rolling stage and the amount and type of ear plucking after cold reduction to the final gauge; and Fig. 3 shows a diagram illustrating the influence of cold reduction before intermediate annealing and the effect on the type and degree of ear plucking after cold reduction to the final gauge. DETAILED DESCRIPTION OF THE INVENTION EMBODIMENTS

[036] Sufficiently high strength and formability (including limited earing) are among the main requirements for aluminum foil. High strength is needed to achieve sufficient structural stability and to prevent buckling of the can base (dome inversion) under high internal pressure. High strength is also needed to obtain stable cans with very thin tin walls after ironing. Good formability is required as the material undergoes heavy forming operations. Anisotropic material flow due to foil texture – controlled by the balance between hot strip cube and cold rolling texture – always forms an irregular can edge during deep drawing and ironing operations. Petition 870250108948, dated 11 / 27 / 2025, page 25 / 44 16 / 25 This irregularity is also known as earing. Highly irregular cup strips are detrimental to the transport of can bodies or affect the entire process when the ears are stretched and cut during ironing, leading to machine downtime and reduced efficiency.

[037] The embodiments of the invention are capable of satisfying both requirements satisfactorily using an economically viable production process.

[038] Figure 1 shows a schematic drawing of a part of a 100 installation configured to manufacture aluminum tin foil suitable for making cup-shaped articles. The schematic figure shows only some of the devices used in the production route.

[039] The production facility typically includes casting devices to produce large molten aluminum alloy casting ingots. The cast ingots typically consist of coarse grains with dendritic structure and random texture. Precipitates comprising aluminum and other constituents such as Fe, Mn, and Si are typically distributed non-homogeneously in the cast ingot.

[040] In a next step, the molten ingots are homogenized in a homogenization furnace (also called a preheating furnace, not shown in Fig. 1). The homogenization treatment is typically accompanied by characteristic changes in solute content and precipitation microstructure, subsequently affecting recrystallization, grain size and texture during sheet production. Petition 870250108948, dated 11 / 27 / 2025, page 26 / 44 17 / 25

[041] The homogenized ingots are then transferred to the hot rolling stage. A single-support reversible mill 120 is used for hot rolling in the preferred installation. The single-support reversible mill 120 is capable of being operated in two different operating modes shown separately in schematic Fig. 1. In a first operating mode HR-FP (shown on the left side of the single-support reversible mill 120), the incoming ingots are reduced in thickness using multiple flat passes where the material is wound back and forth without being wound on both sides of the mills. In a second operating mode HR-CP, shown on the right side of the drawing representing the single-support reversible mill 120, winding coils CR on both sides of the MS rolling support are used to wind the SH sheet between winding passes performed in mutually opposite rolling directions.In both winding passes, one of the coils is operating as a compensating coil, providing an entry strip for the rolling gap formed in the rolling mill support. The other coil is used as a tension coil that winds the exit strip after the rolling path. Since single-support reversible rolling mills are generally known in the art, a detailed description is considered unnecessary in this application.

[042] The hot-rolled material is then – after cooling – transferred as a coil to a cold rolling stage 130 arranged downstream of the hot rolling stage in the direction of material flow. The cold rolling mill may be single-supported (as shown) Petition 870250108948, dated 11 / 27 / 2025, page 27 / 44 18 / 25 or a multi-support cold rolling mill.

[043] A batch furnace 140 is arranged downstream of the cold rolling stage 130. The batch furnace is configured to receive multiple CL coils after cold rolling and to perform intermediate annealing of the cold material to achieve complete recrystallization of the sheet material.

[044] Another cold rolling stage 150 is arranged downstream of the intermediate batch annealing furnace 140 to apply cold rolling to the recrystallized material to obtain cold-rolled material in the desired final gauge for further processing steps, for example, as an H1X material or, more specifically, as an H19 material. The cold rolling mill 150 comprises a single support in the embodiment of Fig. 1.

[045] An exemplary process for producing aluminum tin foil in plant 100 was carried out as follows.

[046] In a preparatory step, an aluminum alloy was melted to form a casting and subsequently roughed out to obtain a cast and roughed aluminum alloy body suitable for further processing. This body is also referred to as an ingot to be followed. The aluminum alloy may be a can body stock material, such as AA3004, AA3104, or another aluminum alloy basically suitable for making aluminum tin foil.

[047] The aluminum alloy used in exemplary processes comprised about 0.30% by weight of Si, about 0.50% by weight of Fe, about 0.95% by weight of Mn, about 1.10% by weight of Mg, about 0.20% by weight of Cu, less than 0.05% by weight of Ti, less than 0.10% by weight of Zn; and up to 0.15% in Petition 870250108948, dated 11 / 27 / 2025, p. 28 / 44 19 / 25 weight of impurities, preferably each of the impurities less than 0.05% by weight, with the remainder as Al.

[048] After casting and roughing, the ingot was homogenized at approximately 500 - 595°C with an immersion time of, for example, 5 to 20 hours, followed by cooling of the ingot to approximately 490 - 530°C.

[049] The homogenized ingot (aluminum body) was then transferred to the hot rolling mill without significant intermediate cooling, so that hot rolling of the ingot began at around this temperature, i.e., at about 490 - 530°C. A 120 single-support reversible rolling mill was used as the hot rolling mill in this installation configuration.

[050] Several flat passes were carried out, up to about 25 to 45 mm in gauge. The ingot temperature after the last flat pass was between about 290 and 350°C. The number of flat passes can vary, for example, from 15 to 50.

[051] After the flat passes, the material thickness was further reduced by hot rolling on the same 120 single-support reversible mill, with the difference that the material was wound after each pass (winding passes). The number of winding passes was from 2 to 8.

[052] The thickness of the material after the last winding pass was about 1.7 mm to about 5 mm. In the experiments reported here, the exit temperature of the material after hot rolling, i.e., the Threx hot rolling exit temperature, was low enough to ensure the absence of recrystallization. Typically, the Petition 870250108948, dated 11 / 27 / 2025, page 29 / 44 20 / 25 hot rolling outlet temperature was in a range of about 200°C to about 340°C and preferably between about 220°C and about 280°C. The reduction of each winding pass was between 20 and 70%.

[053] The hot-rolled material was cooled and then transferred to a cold rolling mill.

[054] A cold reduction from 5% to 70% was applied to the material in the cold rolling mill directly onto the hot band of the unrecrystallized material.

[055] The cold-rolled sheet was then transferred from a rolled form to a batch furnace 140 for intermediate annealing. An intermediate annealing step was then applied to the cold-rolled sheet. The annealing temperatures and annealing times were selected so that the annealed material could become fully recrystallized and develop a strong cube texture. A typical annealing temperature range is 280°C to 450°C with 1 to 12 hours of holding time.

[056] The recrystallized annealed sheet was then subjected to cold rolling to apply an appropriate cold reduction to produce a cold-rolled sheet with the final gauge. Preferably, cold rolling with a 70% to 95% reduction was applied to the recrystallized sheet, giving the material the necessary strength and balancing the cube texture with the rolling texture. In the case of recrystallization (partial or total) in the hot band thickness (either self-annealing or after discontinuous annealing), the cube texture developed after annealing was weak and the final product had high Petition 870250108948, dated 11 / 27 / 2025, pp. 30 / 44 21 / 25 earing 45º.

[057] With the method described above, the hot non-recrystallized strip undergoes a relatively low cold reduction and then an intermediate annealing is applied to the material to make it fully soft. With this method, there is an intermediate reduction in thickness of annealing with cold rolling without deterioration of the strong texture of the cube and after annealing.

[058] The combination of low cold reduction to non-recrystallized structure directly after hot rolling and discontinuous annealing to produce fully recrystallized material can also be applied to the conventional method of producing can body stock using a tandem hot rolling mill. In other words, in an alternative embodiment, a tandem hot rolling mill can be used instead of a single-support reversible rolling mill to perform the hot rolling step that precedes the cold rolling step.

[059] Next, some characteristic aspects of the new and beneficial process are explained in connection with the schematic diagrams in Figs. 2 and 3. Fig. 2 schematically illustrates the technical connection between the degree of recrystallization of the sheet material after the initial hot rolling stage and the amount and type of earling after the application of cold reduction to the final gauge. Fig. 3 illustrates the importance of the cold reduction stage before intermediate annealing and the effect on the type and degree of earling after cold reduction to the final gauge.

[060] In each diagram of Figs. 2 and 3, the x-axis represents the degree of cold reduction (in percentage) Petition 870250108948, dated 11 / 27 / 2025, pp. 31 / 44 22 / 25 applied after intermediate annealing. In other words, the x-axis represents the amount of cold reduction achieved in the cold rolling mill 150 located downstream of the intermediate annealing furnace 140. The y-axis represents the type and amount of earlobe (in percentage). The area above the baseline BL corresponds to an earlobe of 0-90°, while the area below the baseline BL represents an earlobe of 45°. The absolute distance of a data point from the baseline in the y-direction of the diagram represents the amount or strength of the respective earlobe, meaning that a point on the baseline BL corresponds to a sheet showing no earlobe. The curves in the diagram represent general trends established in a large number of experiments. The schematic box plots BP in Fig. 3 indicate that the trends represented by the lines are considered significant.

[061] Fig. 2 basically illustrates the importance of the requirement that the hot rolling outlet temperature be selected so that any recrystallization of the hot-rolled sheet is avoided as much as possible.

[062] The solid line represents a case where the rolled sheet is substantially unrecrystallized after the hot rolling operation is complete. This is an embodiment of the claimed invention. For comparison, the lower curve (dashed line) represents reference cases where the sheets were partially recrystallized after the hot rolling stage was complete, which, in other words, means that the Petition 870250108948, dated 11 / 27 / 2025, pages 32 / 44 23 / 25 Recrystallization was not sufficiently avoided in the reference processes presented. The continuous line shows that there is a high degree of 0-90° earing in the fully recrystallized material after intermediate annealing and before the start of cold reduction (at a cold reduction value of 0%). As cold reduction is increased, the degree of 0-90° earing is continuously decreased, so that shortly before obtaining the final gauge (at the highest point of cold reduction) there is no discernible earing (the solid curve crosses the baseline). In the final product after applying full cold reduction to the sheet, a certain amount of 45° earing is discernible, but the degree of earing is low in absolute terms.

[063] In contrast, where the material shows a significant amount of recrystallization after the hot rolling stage is complete (dashed line), the 0-90° earing degree is less than in the cases according to the embodiments of the invention. As the cold reduction is increased, the 0-90° earing degree decreases and would disappear completely in a cold reduction that is not sufficient to obtain the thinner final gauge. As the amount of cold reduction is increased to obtain the thinner final gauge, the character of the earing changes from 0-90° to a predominantly 45° earing, and the amount of 45° earing increases to a much higher level in absolute terms than in the material according to the claimed process (solid line). This shows that the degree of recrystallization after the hot rolling stage has a significant influence on Petition 870250108948, dated 11 / 27 / 2025, pages 33 / 44 24 / 25 quantity and in the nature of the earring in the final product.

[064] The diagram in Fig. 3 can be read in a similar way. The diagram illustrates the importance of the cold reduction step applied before immediate annealing. In the diagram, the upper curve (dashed line) corresponds to a case where no cold reduction was applied before annealing. This could be a process similar to the processes described in the prior art mentioned at the beginning of this application. It can be seen that a high degree of 0° - 90° earling is present immediately after intermediate annealing. When the material is finally cold rolled to the final gauge (maximum amount of cold reduction) there is almost no or very little earling in the final product. If a certain amount of 45° earling is present, the absolute amount is small.

[065] In contrast to this, the dashed line below the dashed line represents processes according to embodiments of the invention where a cold reduction is applied before intermediate annealing by cold rolling the material (essentially non-recrystallized) from the hot rolling state before the material is transferred to intermediate annealing. Initially, before the application of cold reduction, the amount of 0-90° angulation is less than in the case of no cold reduction before annealing. Once the sheet thickness is reduced to the final gauge (at maximum cold reduction), there is a significant amount of 45° angulation, which is a property desired by many can manufacturers working with very thin aluminum sheet. Petition 870250108948, dated 11 / 27 / 2025, pages 34 / 44 25 / 25

[066] The description of this patent application also refers to a method for making an aluminum can comprising the steps of the method for producing an aluminum tin sheet, wherein the cold-rolled sheet with the final gauge is formed into a cup-shaped article suitable for making an aluminum can. Petition 870250108948, dated 11 / 27 / 2025, pp. 35 / 44

Claims

1 / 3 CLAIMS 1. Method for producing an aluminum tin sheet comprising the following steps: providing a body made of an aluminum alloy; wherein the aluminum alloy consists of 0.05 to 0.60% by weight of Si; 0.10 to 0.80% by weight of Fe; 0.70 to 1.50% by weight of Mn; 0.80 to 1.50% by weight of Mg; 0.05 to 0.25% by weight of Cu; up to 0.10% by weight of Ti; up to 0.25% by weight of Zn; and up to 0.15% by weight of impurities; with the remainder as Al, characterized by heating the body to a homogenization temperature; hot rolling said body in a hot rolling mill to produce a hot rolled sheet, said hot rolled sheet exiting the hot rolling mill (120) at a hot rolling outlet temperature with a hot rolling mill outlet gauge (120), wherein the hot rolling outlet temperature is selected to be in a range of 200°C to 290°C to avoid recrystallization of the hot rolled sheet;cold rolling the hot-rolled sheet in a cold rolling mill (130) to apply a cold reduction to produce a cold-rolled sheet with a cold rolling mill exit gauge smaller than the hot rolling mill exit gauge; annealing the cold-rolled sheet in a selected intermediate temperature range to allow recrystallization of the cold-rolled sheet to obtain a recrystallized annealed sheet; cold rolling the recrystallized annealed sheet to apply a cold reduction to produce a cold-rolled sheet with a final gauge.

2. Method according to claim 1, characterized in that the aluminum alloy comprises: 0.15 to 0.5% by weight of Si; 0.25 to 0.70% by weight of Fe; 0.80 to 1.40% by weight of Mn; 0.90 to 1.30% by weight of Mg; 0.10 to 0.25% by weight of Cu; up to 0.15% by weight of impurities, each of the impurities less than 0.05% by weight; with the remainder as Al.

3. Method according to claim 1, characterized by a single-support reversible rolling mill (120) being used as a hot rolling mill.

4. Method according to claim 3, characterized in that the single-support reversible rolling mill (120) is used in two different modes of operation, wherein a first mode of operation includes one or more flat passes and a second mode of operation, used after the first mode of operation, includes one or more winding passes producing rolled sheet having the output gauge of the hot rolling mill.

5. Method, according to any of the preceding claims, characterized by a cold reduction between 5% and 70% being applied in the cold rolling mill (130) Petition 870260054024, dated 03 / 06 / 2026, p. 11 / 15 3 / 3 that rolls the hot-rolled sheet.

6. Method, according to any of the preceding claims, characterized in that the annealing of the cold rolled sheet is carried out in a batch furnace (140).

7. A method, according to any of the preceding claims, characterized by a total reduction of more than 70% being applied to the aluminum foil between the exit gauge of the hot rolling mill and the final gauge. Petition 870260054024, dated 03 / 06 / 2026, p. 12 / 15

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