JP2009242830A - Aluminum alloy sheet for bottle can and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum alloy sheet for a bottle can, having excellent workability and strength, and suitable for reduction in the thickness and weight of the bottle can, and to provide a method for producing the same. <P>SOLUTION: The aluminum alloy sheet for the bottle can composed of, by mass, 0.15 to 0.4% Cu, 0.8 to 1.5% Mg, 0.7 to 1.1% Mn, 0.4 to 0.8% Fe and 0.1 to 0.4% Si, and the balance Al with inevitable impurities. The 0.2% proof stress of the aluminum alloy sheet after subjected to baking treatment at 210&deg;C for 10 min is 230 to 270 N/mm<SP>2</SP>, and when from the 0.2% proof stress of the aluminum alloy sheet after subjected to cold working at a cold working ratio of 45% then subjected to the baking treatment at 210&deg;C for 10 min, the 0.2% proof stress of the aluminum alloy sheet before subjected to the above cold working is subtracted to obtain a value, the value is 8 to 28 N/mm<SP>2</SP>. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an aluminum alloy plate used for a bottle can made of an Al—Mn—Mg-based aluminum alloy and a method for producing the same, and more particularly to an aluminum alloy plate for a bottle can suitable for reducing the thickness and weight and a method for producing the same.

  Conventionally, as a packaging container having a reseal function used for beverage and food applications, as shown in FIG. 1, a bottom portion 6, a body portion 2, a neck portion 3, a threaded screw portion 5 and a curled portion An opening provided with a bottle can (two-piece bottle can) 1, a body portion 2, a neck portion 3, a threaded screw portion 5, and a curled portion 7. There is known a bottle can (three-piece bottle can) 1 in which a portion 4 is integrally formed, and a bottom end wall forming a bottom portion 6 is joined to the integrally formed body portion 2.

  In order to increase cost competitiveness in these containers, it is effective to reduce the wall thickness and reduce the cost. However, in this case, the two-piece bottle can has its own molding process and can shape. It is necessary to keep the three points of pressure-resistant strength, can body buckling strength, and screw portion buckling strength in a well-balanced manner. In addition, in neck molding and curl molding, it is necessary to prevent the occurrence of wrinkles, streaks, etc. that cause slow leak after capping, and the generation of cracks during ironing molding.

And various things are proposed as an aluminum alloy plate used for a 2 piece bottle can from these needs. For example, in Patent Document 1, the size and number density of chemical components and second phase particles are controlled within a predetermined range, and the yield strength after baking at 210 ° C. for 10 minutes is set to a range of 230 to 260 N / mm ^2. An aluminum alloy plate and a manufacturing method have been proposed.

In Patent Document 2, the chemical component is controlled within a predetermined range, the Mn solid solution amount is controlled within a range of 0.1 to 0.17%, and the 0.2% proof stress is less than 265 N / mm ^2. An aluminum alloy plate and a manufacturing method have been proposed.

Furthermore, in Patent Document 3, the chemical composition is controlled within a predetermined range, the 45 ° ear ratio in the molded cup is in the range of 2.5 to 5.0%, and the proof stress after baking at 210 ° C. for 10 minutes. An aluminum alloy plate and a manufacturing method have been proposed, characterized in that the Nd is 245 N / mm ² or more.

In any of these Patent Documents 1 to 3, the desired material properties are obtained by performing cold rolling without performing intermediate annealing in the material manufacturing process, and formability (that is, workability). And ensuring the strength of the can.
JP 2006-77278 A (paragraphs 0012 to 0030) JP 2006-77310 A (paragraphs 0019 to 0040) JP 2006-299330 A (paragraphs 0014 to 0034)

However, the conventional aluminum alloy plate has the following problems.
As mentioned above, it is necessary to improve workability and can strength in order to reduce the thickness and weight in order to increase cost competitiveness in containers, but depending on the cold rolling conditions in the manufacturing process, the work hardening characteristics of the material Changes, which will affect workability and can strength. Therefore, in order to further reduce the thickness and weight, further improvements are required in the characteristics and manufacturing method of the aluminum alloy plate for bottle cans.

  Further, in any of Patent Documents 1 to 3, work hardening characteristics are not mentioned, and as can be seen from Examples in Patent Documents, the thickness is 0.4 mm (Patent Documents 1 and 2). ) Or 0.36 mm (Patent Document 3), and there is a limit in proceeding to reduce the thickness and weight. Therefore, when proceeding to reduce the thickness and weight of 2-piece bottle cans, the conventional technology that specifies chemical components, particle size and solid density, solid solution amount of specific elements, yield strength after baking, etc. is not sufficient in terms of materials. Therefore, it is necessary to optimize the work hardening behavior (work hardening characteristics) of the material.

  The present invention has been made to solve the above-mentioned problems, and its object is to provide an aluminum alloy plate for a bottle can excellent in workability and strength and suitable for reducing the thickness and weight of the bottle can and a method for producing the same. There is to do.

  As a result of diligent research, the inventors of the present application have found that a material production process of a hot-flow direct coil type (without intermediate annealing), which is currently mainstream, is processable in a can manufacturing process of a two-piece bottle can, and a can of a two-piece bottle can With the aim of providing materials that can reduce the thickness and weight of 2-piece bottle cans by improving the strength, especially cold rolling conditions and accompanying work hardening behavior (addition of processing to the base plate) We focused on optimizing the strength increase at this time (here, 0.2% yield strength increase). As a result, the present inventors have found an aluminum alloy plate for bottle cans (hereinafter, appropriately referred to as “aluminum alloy plate”) that satisfies the above-mentioned purpose and a method for producing the same.

  The workability in the present invention refers to, for example, iron moldability, neck moldability, and the like, and the can strength in the present invention refers to, for example, bottom pressure strength (hereinafter, simply referred to as pressure strength). It means the can body buckling strength, the threaded portion buckling strength, and the like. Moreover, the work hardening behavior (work hardening characteristic) referred to in the present invention means an increase in strength accompanying an increase in plastic strain when processing is performed at a low temperature. Specifically, it refers to the degree of increase in strength of the side wall portion and neck forming portion when canning is performed on an aluminum alloy plate.

That is, in order to solve the said subject, the aluminum alloy plate for bottle cans which concerns on this invention is Cu: 0.15-0.4 mass%, Mg: 0.8-1.5 mass%, Mn: 0.7 -1.1% by mass, Fe: 0.4-0.8% by mass, Si: 0.1-0.4% by mass, the balance being Al and inevitable impurities made of aluminum alloy for bottle cans A 0.2% proof stress of 230 to 270 N / mm ² after baking at 210 ° C. for 10 minutes in the aluminum alloy plate for bottles, and 45% in the aluminum alloy plate for bottles From the 0.2% proof stress when the cold-worked sheet is subjected to a baking treatment at 210 ° C. for 10 minutes, the cold work is applied at a cold working rate of Of the aluminum alloy plate for the bottle can Minus the strength (hereinafter referred to as increment of 0.2% proof stress) is characterized in that it is a 8~28N / mm ^2.

  According to such a configuration, the workability and strength of the aluminum alloy plate are defined by prescribing each content of Cu, Mg, Mn, Fe, and Si within a predetermined range and further defining the work hardening characteristics. Will improve.

In order to solve the above-mentioned problems, the method for producing an aluminum alloy plate for a bottle can according to the present invention includes Cu: 0.15-0.4 mass%, Mg: 0.8-1.5 mass%, Mn: 0.0. Melting aluminum alloy containing 7 to 1.1 mass%, Fe: 0.4 to 0.8 mass%, Si: 0.1 to 0.4 mass%, the balance being composed of Al and inevitable impurities A first step of casting to produce an ingot, a second step of homogenizing and heat treating the ingot, and a third step of hot rolling the homogenized heat-treated ingot to produce a rolled plate And a fourth step of cold rolling the rolled plate to produce an aluminum alloy plate, and in the fourth step, the cold working rate is controlled in the range of 82 to 88%, and the rolling speed is V (M / min), when the final pass processing rate is X (%), “50 ≦ X + 3.5 × 1 And performing cold rolling under conditions satisfying the equation of ^-3 × V ≦ 71 ".

  According to such a manufacturing method, the workability and strength of the aluminum alloy plate are improved by defining the contents of Cu, Mg, Mn, Fe, and Si within predetermined ranges. Moreover, workability improves by controlling the cold working rate within a range of 82 to 88%. Furthermore, by controlling the relationship between the speed during cold rolling and the final pass processing rate within a predetermined range, the 0.2% proof stress after baking at 210 ° C. for 10 minutes in the aluminum alloy sheet becomes moderate, and 0 .2% yield strength increase is moderate and strength is improved.

  The method for producing an aluminum alloy plate for a bottle can according to the present invention includes the cold rolling, a rolling roller, a plate thickness meter for measuring a plate thickness, a load meter for measuring a rolling load, and a roll of the rolling roller. It is preferable to use a tandem rolling mill having a plurality of rolling stands each having a reduction mechanism for adjusting the gap, a control unit for controlling the reduction mechanism, and a control adjustment device for adjusting the control of the control unit.

  By performing cold rolling with a tandem rolling mill, it is easy to increase the rolling rate in one pass, and therefore, it is possible to shorten the coil handling time, improve the production yield, reduce the energy consumption, and the like.

  According to the aluminum alloy plate for bottle cans according to the present invention, workability and strength are improved. In addition, by using this aluminum alloy plate for bottle cans, it is possible to prevent the occurrence of cracks, wrinkles, streaks, etc. in the two-piece bottle can, and to improve the can strength. The three points of trunk buckling strength and screw portion buckling strength can be maintained in a well-balanced manner. Therefore, by using this aluminum alloy plate for bottle cans, the two-piece bottle can can be reduced in thickness and weight.

  According to the method for manufacturing an aluminum alloy plate for a bottle can according to the present invention, the cold working rate during cold rolling is controlled within a predetermined range, and the relationship between the speed during cold rolling and the final pass working rate is within a predetermined range. The aluminum alloy plate for a bottle can excellent in workability and strength can be obtained by controlling to the optimization of the work hardening behavior of the material. Furthermore, by performing cold rolling with a tandem rolling mill, coil handling time can be shortened, production yield can be improved, energy consumption can be reduced, and cold rolling can be performed efficiently and economically. . Therefore, it is possible to improve the productivity of the aluminum alloy plate.

First, the aluminum alloy plate for bottle cans according to the present invention will be described.
≪Aluminum alloy plate for bottle can≫
The aluminum alloy plate contains a predetermined amount of Cu, Mg, Mn, Fe, and Si, the balance is made of Al and inevitable impurities, and the work hardening characteristics of the aluminum alloy plate are controlled within a predetermined range.
Hereinafter, the reasons for limiting the chemical components of the aluminum alloy plate and the work hardening characteristics of the aluminum alloy plate will be described.

<Cu: 0.15-0.4% by mass>
Cu is an element that contributes to the strength of the aluminum alloy plate. If the Cu content is less than 0.15% by mass, the can strength is insufficient. On the other hand, if it exceeds 0.4% by mass, the work hardening is too large, and the rate of occurrence of cracks (including pinholes, tear-off, etc.) during ironing (including ironing) and wrinkles and streaks during neck molding High, inferior in workability, not suitable for practical use.
Therefore, the Cu content is set to 0.15 to 0.4 mass%.

<Mg: 0.8-1.5% by mass>
Mg is an element that contributes to the strength of the aluminum alloy plate. If the Mg content is less than 0.8% by mass, the can strength is insufficient. On the other hand, if it exceeds 1.5% by mass, the work hardening is too large, and the occurrence rate of cracks (including pinholes, tear-offs, etc.) during ironing, wrinkles and streaks during neck forming is high, and workability is improved. Inferior and not suitable for practical use.
Therefore, the content of Mg is set to 0.8 to 1.5% by mass.

<Mn: 0.7 to 1.1% by mass>
Mn is an element that contributes to the strength of the aluminum alloy plate and is effective for improving the workability by appropriately dispersing the intermetallic compound. If the Mn content is less than 0.7% by mass, the can strength is insufficient. On the other hand, if it exceeds 1.1% by mass, the work hardening is too large, cracking during ironing (including pinholes, tear-off, etc.) occurs, and the size and amount of intermetallic compounds increase excessively. In addition, the occurrence rate of wrinkles, streaks, etc. at the time of neck forming due to coarse intermetallic compounds is high, the workability is inferior, and it is not suitable for practical use.
Therefore, the Mn content is 0.7 to 1.1 mass%.

<Fe: 0.4 to 0.8 mass%>
Fe is an element that is effective for controlling the ear ratio of the aluminum alloy plate within an appropriate range and appropriately dispersing the intermetallic compound to improve workability.
When the Fe content is less than 0.4% by mass, the occurrence of 0-180 ° ears becomes remarkable, and the generation rate of wrinkles during neck molding increases. In addition, the occurrence of edge cuts during cup molding and ironing molding has a high incidence of pinholes, tear-off, etc., which are inferior in workability and are not suitable for practical use. On the other hand, when it exceeds 0.8 mass%, the size and amount of the intermetallic compound increase excessively, and the occurrence rate of wrinkles and streaks during neck forming due to the coarse intermetallic compound is high, and the workability is improved. Inferior and not suitable for practical use.
Therefore, the Fe content is 0.4 to 0.8 mass%.

<Si: 0.1 to 0.4% by mass>
Si is an element that is effective for controlling the ear ratio of the aluminum alloy plate within an appropriate range and appropriately dispersing intermetallic compounds to improve workability.
When the Si content is less than 0.1% by mass, the occurrence of 45 ° ears becomes remarkable, and the generation rate of wrinkles during neck molding increases. In addition, the occurrence of edge cuts during cup molding and ironing molding has a high incidence of pinholes, tear-off, etc., which are inferior in workability and are not suitable for practical use. On the other hand, if it exceeds 0.4% by mass, recrystallization during hot rolling is inhibited, resulting in dispersion of crystal grains, and pinholes, tear-off, etc. are generated due to the occurrence of edge breaks during cup molding and ironing. High rate, inferior processability, not suitable for practical use. In addition, the size and amount of the intermetallic compound are excessively increased, the occurrence rate of wrinkles and streaks at the time of neck formation due to the coarse intermetallic compound is high, the workability is inferior, and it is not suitable for practical use.
Therefore, the Si content is 0.1 to 0.4 mass%.

<Balance: Al and inevitable impurities>
In addition to the above components, the aluminum alloy plate is composed of Al and inevitable impurities. Inevitable impurities include, for example, Cr: 0.10% by mass or less, Zn: 0.50% by mass or less, Ti: 0.10% by mass or less, Zr: 0.10% by mass or less, B: 0.05 Inclusion of less than mass% does not hinder the effects of the present invention, and such inevitable impurities are allowed to be contained.

<Work hardening characteristics>
In the present invention, the work hardening behavior is optimized by controlling the work hardening characteristics within a predetermined range.
That is, as the work hardening characteristic of the aluminum alloy plate, the 0.2% proof stress after baking (heat treatment) at 210 ° C. for 10 minutes on the aluminum alloy plate is set to 230 to 270 N / mm ² . In addition, when the aluminum alloy plate after manufacture is further subjected to cold working at a cold working rate of 45%, the rolled plate subjected to this cold working is subjected to baking at 210 ° C. for 10 minutes. A value obtained by subtracting the 0.2% proof stress of the aluminum alloy sheet before the cold working from 0.2% proof stress (increment of 0.2% proof stress) is 8 to 28 N / mm ² .

[0.2% yield strength after baking at 210 ° C. for 10 minutes: 230 to 270 N / mm ² ]
If the 0.2% proof stress after baking at 210 ° C. for 10 minutes on an aluminum alloy plate is less than 230 N / mm ² , the can strength is insufficient. On the other hand, if it exceeds 270 N / mm ² , the strength is too high, cracking during ironing (including pinholes, tear-off, etc.) occurs, the strength of the neck is too high, and wrinkles and streaks during neck molding Etc. is high, and is inferior in workability and not suitable for practical use.
Therefore, the 0.2% yield strength after baking at 210 ° C. for 10 minutes is set to 230 to 270 N / mm ² .

[0.2% yield strength increase: 8-28 N / mm ² ]
If the increment of 0.2% proof stress is less than 8 N / mm ² , the strength of the screw part will be insufficient after making cans, and the buckling strength (screw part buckling strength) will be reduced. Absent. On the other hand, if it exceeds 28 N / mm ² , the strength of the neck portion is excessively increased, the occurrence rate of wrinkles and stripes at the time of neck formation is high, the workability is inferior, and it is not suitable for practical use.
Therefore, the increment of 0.2% proof stress is 8 to 28 N / mm ² .

  The above-described aluminum alloy plate for a bottle can according to the present invention can be suitably used for a conventional bottle can 1 (here, a two-piece bottle can) as shown in FIG. It is also a suitable material for a laminate (not shown) of an aluminum alloy plate.

Next, the manufacturing method of the aluminum alloy plate for bottle cans which concerns on this invention is demonstrated.
≪Method for manufacturing aluminum alloy sheet for bottle cans≫
The manufacturing method of an aluminum alloy plate includes a first step, a second step, a third step, and a fourth step.
Hereinafter, each step will be described.

<First step>
The first step is a step of producing an ingot by melting and casting an aluminum alloy.
Here, the chemical components of the aluminum alloy are Cu: 0.15 to 0.4 mass%, Mg: 0.8 to 1.5 mass%, Mn: 0.7 to 1.1 mass%, Fe: 0.0. It contains 4 to 0.8% by mass, Si: 0.1 to 0.4% by mass, and the balance is composed of Al and inevitable impurities. Description of each chemical component is as described above, and is omitted here.

<Second step>
The second step is a step of homogenizing heat treatment of the ingot produced in the first step.
The homogenization heat treatment condition is preferably maintained at 570 to 620 ° C. for 2 hours or more. If the homogenization heat treatment temperature is less than 570 ° C. or the holding time is less than 2 hours, it causes variation in texture during hot rolling in the next process, and in the bottle can manufacturing process described later, during DI molding (iron molding) The variation in the ear rate is likely to increase, and it is difficult to obtain a predetermined can size. Further, the remaining non-recrystallized structure tends to cause wrinkles during neck formation and further curl cracks. On the other hand, if it exceeds 620 ° C., the ingot surface is likely to burn, and the production of the aluminum alloy plate itself tends to be difficult.

<Third step>
The third step is a step of producing a rolled plate by hot rolling the ingot that has been subjected to the homogenization heat treatment in the second step.
The hot rolling conditions are preferably set such that the hot rolling start temperature is 450 to 550 ° C., and the hot rolling winding temperature is 300 ° C. or higher. If the start temperature of hot rolling is less than 450 ° C., the rolling load tends to be excessive, and it becomes difficult to produce an aluminum alloy plate. On the other hand, when it exceeds 550 ° C., the growth of the surface oxide film is promoted and the surface quality tends to be deteriorated.
In addition, when the coiling temperature of the hot rolling process is less than 300 ° C., recrystallization in the aluminum alloy sheet does not occur sufficiently, and as a result, coarse crystal grains are likely to be mixed and the material strength is increased, and ironing formability is improved. It tends to decline. Further, the ear rate is increased, and the dimensional defect of the flange portion is likely to occur.

<4th process>
The fourth step is a step of cold rolling the rolled plate produced in the third step to produce an aluminum alloy plate.

In cold rolling, the cold working rate (cold rolling rate) is controlled in the range of 82 to 88%, the rolling speed is V (m / min), and the final pass working rate is X (%). The test is performed under the condition satisfying the formula of “50 ≦ X + 3.5 × 10 ⁻³ × V ≦ 71”.
In addition, the cold work rate here is a cold work rate of the total cold rolling.

[Cold working rate: 82-88% range]
When the cold working rate is less than 82%, the occurrence of 0-180 ° ears becomes remarkable, and the generation rate of wrinkles during neck forming increases. In addition, the occurrence of edge breaks in the direction of 0 ° during cup molding and ironing molding has a high incidence of pinholes, tear-off, etc., and is inferior in workability, and is not suitable for practical use. On the other hand, if it exceeds 88%, the occurrence of 45 ° ears becomes remarkable, and the occurrence rate of wrinkles during neck molding increases. Further, the occurrence of edge breaks in the direction of 45 ° during ironing molding has a high incidence of pinholes, tear-off, etc., is inferior in workability, and is not suitable for practical use.
Therefore, the cold working rate is in the range of 82 to 88%.

[When the rolling speed is V (m / min) and the final pass processing rate is X (%), the expression “50 ≦ X + 3.5 × 10 ⁻³ × V ≦ 71” is satisfied]
When the value of “X + 3.5 × 10 ⁻³ × V” is less than 50, the dynamic recovery of the material is insufficient, and the 0.2% yield strength increase in the work hardening characteristics of the aluminum alloy plate is 8 N / mm ² . Insufficient and, after making the can, the strength of the screw part is insufficient, and the buckling strength (screw part buckling strength) is lowered, so that the function as a product is not satisfied. On the other hand, when it exceeds 71, the dynamic recovery of the material proceeds too much, and the 0.2% proof stress after baking at 210 ° C. for 10 minutes of the aluminum alloy plate is less than 230 N / mm ² , resulting in insufficient can strength.

The dynamic recovery referred to in the present invention is a phenomenon in which dislocations proliferated when the rolled plate is deformed at a high temperature tends to disappear, and as a result, strain hardening becomes small. It is called dynamic recovery to distinguish it from recovery that occurs when the temperature is raised (static recovery). In the present invention, the rolling speed at the time of cold rolling and the processing rate of the final pass are specified. However, the higher these values are, the more heat generation is promoted at the time of rolling, and the dynamic recovery tends to increase. When dynamic recovery is large, the work hardening amount in the next processing step is large, and vice versa when dynamic recovery is small. In addition, in the present invention, “the next processing” is a can manufacturing process, and if the dynamic recovery of the material is insufficient, the strength of the side wall of the can is not sufficiently increased and the buckling strength is increased. It will be insufficient. However, if the dynamic recovery progresses excessively, the strength of the aluminum alloy plate itself is insufficient, so that the can strength is also insufficient.
Therefore, the value of “X + 3.5 × 10 ⁻³ × V” is 50 to 71.

As will be described later, in the present invention, intermediate annealing during cold rolling is not performed, but 0.2% is achieved by controlling the cold working rate within a range of 82 to 88% without performing intermediate annealing. The increase in yield strength can be controlled to 28 N / mm ² or less.

Further, the 0.2% proof stress after baking at 210 ° C. for 10 minutes is controlled to 270 N / mm ² or less because the content of each element of Cu, Mg and Mn is prescribed as described above. By doing. If either element is added excessively, it will exceed 270 N / mm ² .

In the fourth step, intermediate annealing during cold rolling is not performed.
When intermediate annealing is performed, work hardening at the time of molding increases, and neck formability deteriorates due to the occurrence of wrinkles, streaks, etc. at the time of neck molding, and the cost increases due to an increase in processes. is there. In addition, when intermediate annealing is performed, the 0.2% yield strength increase exceeds 28 N / mm ² . Incidentally, when carrying out intermediate annealing before the cold rolling, except that the increment of 0.2% proof stress exceeds the 28N / mm ^2, a 0.2% proof stress after baking of 210 ° C. × 10 minutes 270N / mm It will exceed ² . Further, when intermediate annealing is performed in the middle of cold rolling, the method of generating ears is different, and even if the cold working rate is low, minus ears are not generated.

  Here, the cold rolling in the fourth step is preferably performed with a tandem rolling mill. By using a tandem rolling mill, it is possible to increase the rolling rate in a single sheet pass as compared to a single rolling mill. As a result, the amount of heat generated in one passage can be stably increased, and the coil handling time can be shortened, the production yield can be improved, and the energy consumption can be reduced. Therefore, cold rolling can be performed efficiently and economically, and the productivity of the aluminum alloy sheet is improved.

Next, an example of a tandem rolling mill will be described with reference to FIGS. 2 (a) and 2 (b).
2A and 2B are schematic views schematically showing a tandem rolling mill. In the tandem rolling mill 100, a plurality of (here, 5) rolling stands 11 to 15 are continuously arranged, and the rolling stands 11 to 15 are rolling rollers 21 to 25 for rolling the material 70 to be rolled. And thickness gauges 31 to 35 for measuring the thickness of the material 70 to be rolled, and load meters 41 to 45 for measuring the rolling load. Further, here, tension meters 51 to 56 for measuring the tension of the material 70 to be rolled are disposed between the rolling stands 11 to 15.

  Furthermore, each rolling stand 11-15 is provided with the rolling-down mechanism 61-65 which adjusts the roll gap of the rolling rollers 21-25, and the control part 80 which controls each rolling-down mechanism 61-65 in the tandem rolling mill 100. Is provided. The control of the control unit 80 is adjusted by the control adjustment device 90. The control adjusting device 90 includes, as its function, a gain adjusting means 90a that adjusts a tuning rate α described later according to the rolling speed V.

In the tandem rolling mill 100, the material 70 to be rolled fed from the rewinding reel is passed through the rolling stands 11 to 15 in the direction indicated by the arrow a in FIG. It is wound on a reel. At that time, the control unit 80 adjusts the roll gap at a tuning rate α as a predetermined proportional gain with respect to the apparent roll gap change amount accompanying the change in rolling load. Further, the gain adjustment means 90a adjusts the tuning rate α using a table that associates the rolling speed V with the tuning rate α.
Here, the tandem rolling mill has been described by taking a 5-tandem rolling mill as an example, but a 2-tandem rolling mill, a 3-tandem rolling mill, or a 4-tandem rolling mill may be used.

  The method for producing an aluminum alloy plate according to the present invention is as described above. However, in carrying out the present invention, for example, foreign matter removal is performed between or before and after each step within a range that does not adversely affect each step. Other processes such as a process, a cleaning process, a surface smoothing process, and a distortion correction process may be included.

  Next, an example of a method for producing a bottle can using the aluminum alloy plate will be described with reference to the drawings. 1 is a perspective view schematically illustrating a conventional bottle can (here, a two-piece bottle can), and FIG. 3 is a schematic diagram illustrating a method for manufacturing the two-piece bottle can.

When the aluminum alloy plate according to the present invention is applied to a two-piece bottle can 1 as shown in FIG. 1, as shown in FIG. 3, first, from the aluminum alloy plate A according to the present invention, for example, a diameter of 160 mm. The blank is punched out with a punch having a diameter of 94 mm and cupped, for example, to produce a cup with a diameter of 94 mm. Next, DI molding (ironing molding) is performed on the drawing cup, and a DI can (ironing can) including the body portion 2 and the bottom portion 6 is manufactured. Next, the can body portion end 2a of the ironing can (body portion 2) is trimmed and subjected to unillustrated cleaning, printing and baking (heat treatment at 210 ° C. for 10 minutes), and then the iron forming can (body portion). 2) is necked by die neck processing or the like to form the neck portion 3, and the opened portion is referred to as an opening portion 4. Thereafter, the outer periphery in the vicinity of the opening 4 is formed with a screw to form a screw portion 5 for attaching a screw cap, and the curled portion is formed to form a curled portion 7, whereby the two-piece bottle can 1 is manufactured. .
In addition, the numerical value of the blank in FIG. 3 is an angle of the direction when the rolling direction is 0 °.

  Furthermore, when the aluminum alloy plate according to the present invention is applied to a conventional general laminate material, various resin films applied to a conventionally known laminate material are bonded together with an adhesive or the like. After that, a laminate material is manufactured through a process in which heat treatment is performed at a temperature equal to or higher than the melting point of the resin film.

  Next, the aluminum alloy plate for bottle cans according to the present invention will be specifically described by comparing an example satisfying the requirements of the present invention with a comparative example not satisfying the requirements of the present invention.

≪Preparation of aluminum alloy sheet≫
Aluminum alloys having alloy compositions as shown in Examples 1 to 8 and Comparative Examples 1 to 16 in Table 1 are melted and cast, then homogenized heat treatment, followed by hot rough rolling and hot finish rolling in order. And produced a hot coil.
The conditions for the homogenization heat treatment were 600 ° C. × 4 hours, and the hot rolling conditions were a hot rolling start temperature of 510 ° C. and a hot rolling coiling temperature of 320 to 340 ° C.

Next, the hot coil is subjected to a tandem cold rolling mill (tandem rolling mill) with a cold working rate (total cold working rate) shown in Table 1 and “X + 3.5 × 10 ⁻³ × V”. Cold rolling is performed at a rolling speed (V) and a final pass processing rate (X) so as to obtain the values of aluminum alloy plates (Examples 1 to 6, Comparative Examples 1 to 16) having a thickness of 0.345 mm. did.
The plate thickness of 0.345 mm can be said to be a thin plate thickness because the conventional plate thickness is about 0.360 to 0.40 mm.

≪Characteristics of aluminum alloy sheet≫
And about the aluminum alloy plate of the said Examples 1-8 and Comparative Examples 1-16, 0.2% yield strength after manufacture (namely, after cold rolling), after a baking process (heat treatment) of 210 degreeC x 10 minutes 0.2% proof stress, and after manufacturing (after cold rolling) aluminum alloy plate, further cold working at a cold working rate of 45%, to the rolled plate subjected to this cold working, The 0.2% yield strength when baking at 210 ° C. for 10 minutes was determined by the following measuring method. In addition, an increase in 0.2% yield strength was determined.

[0.2% yield strength after cold rolling]
A JIS No. 5 test piece was taken in the rolling direction from the aluminum alloy plate after cold rolling, and a tensile test was performed using this test piece in accordance with JIS Z2241, and the tensile strength was measured.

[0.2% yield strength after baking at 210 ° C for 10 minutes]
A JIS No. 5 test was taken from an aluminum alloy plate that had been baked at 210 ° C. for 10 minutes. Using this test piece, a tensile test was conducted in accordance with JIS Z2241, and the 0.2% yield strength after baking was measured. did.

[0.2% proof stress after baking at 210 ° C. for 10 minutes in a rolled sheet after cold working is applied at a cold working rate of 45%]
The cold-rolled aluminum alloy plate was cold worked at a cold work rate of 45%, and then the cold-rolled rolled plate was baked at 210 ° C. for 10 minutes. And the JIS5 test was extract | collected from the rolled sheet after this baking process, the tensile test was done based on JISZ2241 using this test piece, and 0.2% yield strength was measured.
In addition, the increment of 0.2% yield strength was calculated | required from the difference of this value and the 0.2% yield strength after the said cold rolling.
These results are shown in Table 1. In Table 1, those not satisfying the configuration of the present invention are indicated by underlining the numerical values.

≪Bottle can manufacturing method≫
Next, using the aluminum alloy plate, a two-piece bottle can was manufactured according to the following procedure.
First, a blank having an outer diameter of 160 mm was punched from an aluminum alloy plate, and the blank was squeezed with a punch having a diameter of 94 mm and cupped to obtain a squeezed cup having a cup diameter of 94 mm. The drawn cup was subjected to DI molding (ironing molding) to obtain a DI can having a body portion having an inner diameter of 66 mm (ironing can). The body part end of this ironing can was trimmed and baked at 210 ° C. for 10 minutes, and then necked by a die neck method until the inner diameter of the opening became 40 mm to obtain a necked product. A screw part and a curl part were formed on the neck part of this necking product by screw / curl molding to form a two-piece bottle can.

≪Evaluation method≫
Using the can during the above molding process and the prepared can, as an evaluation of workability, iron formability (ironing workability), neck formability, strength as evaluation of pressure strength and seat Evaluation of bending strength (can body buckling strength, screw part buckling strength) was performed by the following method.

[Silent formability]
In the DI molding, 10,000 cans were continuously molded, and the iron moldability was evaluated based on the number of pinholes and tear-offs generated at that time. In other words, the number of cans with pinholes and tear-offs is less than 3 cans per 10,000 cans, and the iron moldability is good, “○”, and the number of cans generated is 3 or more, the iron formability is poor. It was set as “x”.

[Neck formability]
In the necking product (number of samples = 20), neck formability was evaluated by confirming the occurrence of wrinkles and streak-like defects. When 20 cans were neck-molded, no wrinkles or streak-like defects were found. Neck formability was good. "○" Was judged as “bad”.

[Pressure strength]
An internal pressure was applied to the two-piece bottle can (number of samples = 10), the maximum internal pressure immediately before the can bottom buckled was measured, and the average value was defined as the pressure resistance. Those having an average value of the maximum internal pressure of 686 kPa or higher were rated as good “◯”, and those with less than 686 kPa were rated as poor “×”.

[Buckling strength]
A compressive load in the axial direction was applied to the two-piece bottle can (number of samples = 10), the load when the neck portion or the body portion buckled was measured, and the average value was defined as the buckling strength. A load having an average value of 1960 N or more was rated as “good” with a good buckling strength, and a load with an average value of less than 1960 N was rated as “poor”.
These test results are shown in Table 2.

As shown in Table 2, in Examples 1 to 8 that satisfy the requirements of the present invention, all evaluation items of ironing formability, neck formability, pressure strength, and buckling strength were obtained even when the plate thickness was reduced. It was good.
On the other hand, in Comparative Examples 1 to 16 that do not satisfy the requirements of the present invention, when the plate thickness is reduced, at least one item among the ironing formability, the neck formability, the pressure strength, and the buckling strength is the example. The result was inferior compared.
Below, the test result of a comparative example is demonstrated.

In Comparative Example 1, since Cu is less than the lower limit of the present invention, the 0.2% proof stress after baking is less than 230 N / mm ² , the can strength is insufficient, and the pressure strength and buckling strength are inferior. In Comparative Example 2, since Cu exceeds the upper limit of the present invention, the work hardening is too large, the 0.2% proof stress after baking exceeds 270 N / mm ² , cracking occurs during iron forming, and iron formability. Was inferior. Moreover, the neck formability was inferior.

In Comparative Example 3, since Mg was less than the lower limit of the present invention, the 0.2% yield strength after baking was less than 230 N / mm ² , the can strength was insufficient, and the pressure strength and buckling strength were inferior. In Comparative Example 4, since Mg exceeds the upper limit of the present invention, work hardening is too large, 0.2% proof stress after baking exceeds 270 N / mm ² , cracking occurs during iron forming, iron formability Was inferior. Moreover, the neck formability was inferior.

Comparative Example 5, since Mn is less than the lower limit of the present invention, a 0.2% proof stress after baking is less than 230N / mm ^2, can strength is insufficient, pressure strength, buckling strength was inferior. In Comparative Example 6, since Mn exceeds the upper limit of the present invention, work hardening is too large, 0.2% proof stress after baking exceeds 270 N / mm ² , cracking occurs during iron forming, iron formability Was inferior. In addition, the size and amount of the intermetallic compound increased excessively, and the neck formability was inferior.

  In Comparative Example 7, since Fe is less than the lower limit of the present invention, the occurrence of 0-180 ° ears was remarkable and the neck formability was poor. In addition, when the cup was formed, the ear was cut during the ironing, and the ironing formability was poor. In Comparative Example 8, since Fe exceeded the upper limit of the present invention, the size and amount of the intermetallic compound increased excessively, and the neck formability was inferior.

  In Comparative Example 9, since Si was less than the lower limit of the present invention, the occurrence of 45 ° ears was remarkable and the neck formability was poor. In addition, when the cup was formed, the ear was cut during the ironing, and the ironing formability was poor. In Comparative Example 10, since Si exceeded the upper limit of the present invention, recrystallization during hot rolling was hindered, causing variations in crystal grains, and ironing formability was inferior. In addition, the size and amount of the intermetallic compound increased excessively, and the neck formability was inferior.

  In Comparative Example 11, since the cold working rate was less than the lower limit of the present invention, the occurrence of 0-180 ° ears was remarkable and the neck formability was poor. In addition, during cup molding and ironing, ear cuts in the direction of 0 ° were generated, and ironing moldability was poor. In Comparative Example 12, since the cold working rate exceeded the upper limit of the present invention, the occurrence of 45 ° ears was remarkable and the neck formability was inferior. In addition, during cup molding and iron molding, ear cuts in the direction of 45 ° occurred, and iron moldability was inferior.

In Comparative Example 13, since the value of “X + 3.5 × 10 ⁻³ × V” was less than 50, the pressure strength was satisfactory, but the dynamic recovery of the material was insufficient, and the 0.2% yield strength increment was 8N. / Mm ² and the buckling strength (screw portion buckling strength) was inferior. In Comparative Example 14, since the value of “X + 3.5 × 10 ⁻³ × V” exceeds 71, the recovery of the material is too advanced, and the 0.2% proof stress after baking is less than 230 N / mm ² , and the can strength The pressure resistance and buckling strength were inferior.

In Comparative Example 15, since the intermediate annealing was performed during the cold rolling, the 0.2% yield strength exceeded 28 N / mm ² and the neck formability was inferior. In addition, the cold working rate is reduced because the intermediate annealing is performed during the cold rolling, but in this case, since the method of generating the ears is different, no minus ears are generated, and the ironing formability is It does not decline. In Comparative Example 16, since the intermediate annealing was performed immediately before the cold rolling, the 0.2% proof stress after the baking treatment exceeded 270 N / mm ² , the work hardening was too large, and cracking occurred during ironing forming. The ironing moldability was inferior. Moreover, the neck formability was inferior. Furthermore, the 0.2% yield strength exceeded 28 N / mm ² and the neck formability was poor.

  As mentioned above, although the best embodiment and the example were shown and explained in detail about the manufacturing method of the aluminum alloy plate for bottle cans and the aluminum alloy plate for bottle cans according to the present invention, the gist of the present invention is limited to the contents described above. Is not to be done. Needless to say, the contents of the present invention can be widely modified and changed based on the above description.

It is a perspective view which shows typically a conventional bottle can (2 piece bottle can or 3 piece bottle can). (A), (b) is a schematic diagram which shows a tandem rolling mill roughly. It is a schematic diagram which shows the manufacturing method of a 2 piece bottle can.

Explanation of symbols

1 Bottle can (2 piece bottle can or 3 piece bottle can)
2 Body part 3 Neck part 4 Opening part 5 Screw part 6 Bottom part 7 Curl part 100 Tandem rolling mill A Aluminum alloy plate for bottle can

Claims (3)

Cu: 0.15-0.4 mass%, Mg: 0.8-1.5 mass%, Mn: 0.7-1.1 mass%, Fe: 0.4-0.8 mass%, Si: An aluminum alloy plate for a bottle can containing 0.1 to 0.4% by mass, the balance being composed of Al and inevitable impurities,
0.2% proof stress after baking at 210 ° C. for 10 minutes in the aluminum alloy plate for bottle cans is 230 to 270 N / mm ^2, and
When the aluminum alloy plate for a bottle can is further cold worked at a cold working rate of 45%, the rolled plate subjected to this cold working is subjected to a baking treatment of 210 ° C. × 10 minutes for 0 minutes. A value obtained by subtracting 0.2% proof stress of the aluminum alloy plate for bottle cans from 8% to 28 N / mm ² before 2% proof stress is applied. Board. Cu: 0.15-0.4 mass%, Mg: 0.8-1.5 mass%, Mn: 0.7-1.1 mass%, Fe: 0.4-0.8 mass%, Si: A first step of producing an ingot by melting and casting an aluminum alloy containing 0.1 to 0.4% by mass and the balance being composed of Al and inevitable impurities;
A second step of homogenizing heat treatment of the ingot;
A third step of hot rolling the homogenized heat-treated ingot to produce a rolled plate;
A fourth step of cold rolling the rolled plate to produce an aluminum alloy plate,
In the fourth step, the cold working rate is controlled in the range of 82 to 88%, the rolling speed is V (m / min), and the final pass working rate is X (%).
50 ≦ X + 3.5 × 10 ⁻³ × V ≦ 71
A method for producing an aluminum alloy plate for a bottle can, characterized by performing cold rolling under conditions satisfying the formula: The cold rolling is a rolling roller, a plate thickness meter for measuring a plate thickness, a load meter for measuring a rolling load, and a plurality of rolling stands each including a rolling mechanism for adjusting a roll gap of the rolling roller, The method for producing an aluminum alloy plate for a bottle can according to claim 2, wherein the tandem rolling mill has a control unit that controls the reduction mechanism and a control adjustment device that adjusts the control of the control unit.

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