JPH0456743A - Aluminum alloy for negative pressure can, its manufacture and negative pressure can body - Google Patents

Abstract

PURPOSE:To obtain an Al alloy sheet for a negative pressure can for noncarbonated drinks in which the can bottom part deforms preferentially to the can side part at the time when the pressure of the inside of the can turns into negative one by using the sheet material of an Al alloy contg. specified amounts of Mn and Mg or other alloy elements as the material for a DI can. CONSTITUTION:As the material for a DI can for noncarbonated drinks such as fruit juice and coffee, and Al alloy contg., by weight, 0.5 to 1.5% Mn and 0.5 to 2.0% Mg, or furthermore contg. one or >= two kinds among 0.2 to 0.7% Fe, 0.1 to 0.5% Si, 0.05 to 0.5% Cu and 0.1 to 1.0% Zn and the balance Al is used. The cast slab of this Al alloy is subjected to homoge nizing heat treatment at >=550 deg.C and is thereafter subjected to ordinary hot rolling, cold rolling and process annealing into a thin sheet material having 18 to 25kg/mm<2> tensile strength to manufacture a DI can. The strength of side part of the DI can is >=1.2 times that of the can bottom part and at the time the pressure in the can reduces into the negative one of <1kg/cm<2> after the can is filled with coffee or the like at a high temp. and is thereafter cooled, the can bottom part is concaved and deforms inwardly in the ratio of 8 to 15ml preferentially to the can side part and the pressure in the can therefore reduces into positive one and free from the need of using an N2 gas can be obtd.

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a DI can body for non-carbonated beverages such as fruit juice and kho-kho.More specifically, the present invention relates to a DI can body for non-carbonated beverages such as fruit juice and kho-kho. The present invention relates to a DI negative pressure can body for non-carbonated beverages that has a
With carbonated drinks such as beer and cola. There are non-carbonated drinks such as fruit juice and coffee. In the former case, a two-piece DI can (made of aluminum or steel) with a thin can side wall is used as a container, which is characterized by a lightweight can that does not cause dents in the can side wall because it contains carbon dioxide gas. On the other hand, the latter does not contain carbon dioxide gas and is filled hot (approximately 90°C), so it is under negative pressure (0°4 kg) at room temperature.
/ cm”), therefore, a three-piece steel can with a highly rigid side wall is used as a container.The two types of containers listed above (a two-piece DI can and a three-piece steel can) are used as containers. Yes, DI cans are manufactured from plates by drawing and ironing (DI) processing.Also, 3-piece cans are manufactured by welding or gluing plates together.These cans differ in their processing methods, etc. The side wall portion of the can is different from 0.11 to 0.13 m +++ in the DI can method, and around 0.2 mm in the 3-piece can method, and the DI processing method is advantageous because there is a large difference in the amount of can shape. By the way, in recent years, due to advances in nitrogen filling technology, DI cans have begun to be used as containers for non-carbonated beverages.This technology creates a positive pressure (1 kg) inside the can by filling nitrogen.
/ am" or more). It is possible to prevent dents on the side wall of the can. This method is mainly used for sports drinks, but recently it has been put into practical use for other contents (oolong tea). However, there are difficulties in terms of equipment and technology to adopt this technology (nitrogen filling), and it is desired that DI cans be used without nitrogen filling. Due to the current situation, developments other than nitrogen filling technology have been progressing.For example, there is a method of adding beads to the side wall of the can to increase the rigidity of the side wall, and this method is disclosed in Japanese Patent Publications No. 54-14552, No. 54-14553, and Japanese Patent Application Publication No. 54-14553. No. 125149/1982 has been proposed.More recently, there is a method proposed by the present inventors (Patent Application No. 2) in which the can bottom is deformed inward.On the other hand, in terms of materials, 3004 alloy is often used as a hard material, and the feature of this material is that it has excellent DI workability.However, since this material is a hard material, the strength of the can side wall and can bottom remains almost the same (can Therefore, in the case of negative pressure cans, the thinner side wall portions have weaker rigidity and preferentially cause dents. The object of the present invention is to solve the problems of the prior art, to provide a material particularly suitable for DI cans for non-carbonated beverages, and to provide a manufacturing method thereof and DI cans for non-carbonated beverages. DI cans for non-carbonated beverages can be adopted using the above three methods (nitrogen filling, side wall bead processing, and inward deformation of the bottom of the can).
However, from the viewpoint of eliminating the need for nitrogen filling, the side wall bead processing method and the method of deforming the can bottom inward are ideal. Among these methods, the side wall bead processing method has problems such as defects in the coating film, so the method of deforming the can bottom inward is more advantageous. However, since it is very difficult to avoid thickening of the side wall of the can using conventional techniques, the present inventors have conducted intensive research on measures (reducing the thickness of the side wall) that can effectively solve this problem. As a result of this progress, the present invention has been achieved. That is, the present invention (present invention 1) has Mn: 0.5 to 1.
5% and Mg: 0.5 to 2.0%, and further Fe:
0.2-0.7%, Si: 0.1-0.5%, Cu: 0
．． 05 to 0.5% and Zn: O, 1 to 1.0%, and the remainder is substantially AM. An aluminum alloy plate for negative pressure cans is characterized in that its strength is 1.2 times or more higher than that of the can bottom, and the can bottom can be preferentially deformed when the inside of the can becomes negative pressure. This is a summary. In addition, in this method for producing an aluminum alloy plate for a negative pressure can (invention 2), an aluminum alloy ingot having the above-mentioned chemical composition is
After homogenization heat treatment at 50°C or higher, a plate that has been subjected to a combination of normal hot rolling, cold rolling and intermediate annealing is annealed to a tensile strength of 18 to 25 kg/am. In DI cans, the strength of the collapsible wall part is more than 1.2 times higher than that of the can bottom, and when the inside of the can becomes negative pressure, the can bottom deforms preferentially to obtain a material that yields 2. Further, the D1 negative pressure can body according to the present invention (invention 3) is a DI can of the aluminum alloy plate obtained in the invention 2,
When the internal pressure of the can becomes less than 1) cg/c+a'', the bottom of the can deforms to the inside of the can, and the internal volume of the can decreases by 8 to 15+iQ, resulting in the internal pressure of the can becoming positive (1 kg/cl12 or more). The present invention will be explained in more detail below. (Function) First, the reasons for limiting the chemical components in the present invention will be explained. Mn: Mn is an important element for improving strength and ironing workability. In Although,
If it is less than 0.5%, there is no effect. On the other hand, if it exceeds 1.5%, the strength becomes too high and large intermetallic compounds are formed, reducing formability. Therefore, Mn is set in the range of 0.5 to 1.5%. Mg: Mg is an important element for improving strength, and coexisting with Mn, is an important element for stabilizing the aperture. However, if it is less than 0.5%, there is no effect, and 2%
, when it exceeds 0%, the strength becomes too high and the moldability deteriorates. Therefore, Mg should be in the range of 0.5 to 2.0%. Although the above-mentioned Mn and Mg are the main components, it is necessary to further contain one or more of the following elements Fe, Si, Cu, and Zn in appropriate amounts. Fe: Fe forms an Al-Mn-Fe-based compound with Mn, and is an important element for improving ironing workability. However, if it is less than 0.2%, this effect cannot be obtained;
, when it exceeds 7%, large intermetallic compounds are formed, which promotes deterioration of formability. Therefore, Fe is 0.2~0
．． The range shall be 7%. Sj: Si is an element that is effective in lowering the thickness by reducing the Fe/Si ratio and improving ironing workability by phase transformation into the above-mentioned metal compound (formation of α phase). However, if it is less than 0.1%, there will be no effect, and if it exceeds 0.5%, it will cause cracking problems during casting. Therefore, Si is 0.1 to 0
．． The range shall be 5%. Cu: Cu is effective in improving strength, especially when performing intermediate annealing at high temperatures (
When performing short-time annealing at 430°C or higher, it has the effect of providing precipitation hardening of Al-Cu-Mg with Mg during baking during the can manufacturing process. However, if it is less than 0.05%, neither effect can be obtained.
Moreover, if it exceeds 0.5%, corrosion resistance will deteriorate. Therefore, Cu is in the range of 0.05 to 0.5%. Zn: Zn is an element that is effective in making intermetallic compounds fine and uniform, but if it is less than 0.1%, this effect cannot be obtained, and if it exceeds 1°0%, the effect will be saturated. Therefore, it becomes a waste. Therefore, Zn is in the range of 0.1 to 1.0%. Next, a method for manufacturing an aluminum alloy plate will be explained. The aluminum alloy ingot having the above chemical composition is subjected to homogenization heat treatment. The purpose of this heat treatment is to homogenize the ingot structure, improve hot rolling properties, and reduce the profile of the product plate. However, since neither effect is obtained below 550°C, the homogenization heat treatment must be performed at a temperature of 550°C or higher. There is no upper limit to the heating temperature, but since the burning temperature of aluminum alloys is generally 600°C,
The limit is 00°C. Also. The holding time is also not particularly limited, but it is preferably 1 hour or more. Next, hot rolling, cold rolling, and intermediate annealing are performed, and these may be performed using conventional methods and conditions. Specifically, for example, the hot rolling end thickness is 5 mm or less, the temperature is 280° C. or more, and intermediate annealing may be either continuous annealing or batch annealing. In addition, cold rolling is performed either before or after intermediate annealing, and the total rolling reduction is 50%.
The above shall apply. Thereafter, finish annealing, which is one of the key points of the present invention, is performed. This annealing has a large effect on the strength of the side wall and bottom of the can. Regarding the annealing conditions, the tensile strength of the product plate is 18 kg/+
If it is less than “u+”, the pressure resistance of a negative pressure can is about 3 kg/am.
”(Negative pressure cans are retorted after filling with contents.
It is sterilized with 'C, and the pressure resistance at this time is approximately 3K.
g/c■2), and 25kg/l
If the area exceeds 1 m2, the strength of the collapsed wall is 1.
However, the can bottom does not turn over when the inside of the can becomes negative pressure, making it difficult to reduce the thickness of the can side wall. therefore,
Finish annealing is performed under conditions that provide the above strength. Specifically, for example, when continuous annealing is performed, the temperature reached is 250
~430°C (however, heating and cooling rate: 100°C/win or more), and when batch annealing is performed, the range is from 200°C to
The temperature range is 400°C. As long as the above strength is obtained, 0
In the case of one can, the strength of the side wall of one can is 1.
Since the height is more than twice as high, the can bottom can be deformed preferentially when the inside of the can becomes negative pressure. Next, conditions for the negative pressure can of the present invention will be explained. As mentioned above, negative pressure cans are required to withstand pressure and strength against negative pressure, and while pressure resistance can be satisfied with the above-mentioned strength, in the case of negative pressure, a special can bottom shape is required. . In other words, the bottom of one can is shaped to be easily deformed inward. Furthermore, when used as a negative pressure can, it is important that the can is not dented when held in the hand. The internal volume of the can decreases by 8m.
This cannot be satisfied with less than Q, and 1511
If the IQ is exceeded, it becomes difficult to deform the can bottom. Therefore, as a DI negative pressure can, the internal pressure of one can is 1 kg/
cm", the bottom of the can deforms inside the can, and it is necessary to satisfy the condition that the amount of reduction in the internal volume of the can is in the range of 8 to 15+++n. As a result, the internal pressure of the can becomes positive pressure (1k
g/cm"), and can preferentially prevent the occurrence of dents on the side wall of the can even when the can is held by hand. There are no particular regulations regarding the shape of the bottom of the can, and as long as it is a shape that easily deforms inward. For example, the shape of the can bottom shown in Fig. 1 is a so-called caldera-like shape in which the can bottom continuously bulges out in a concave shape from the center of the can bottom toward both ends, and protrudes like legs near both ends of the can bottom. (Example) Next, an example of the present invention will be shown. An aluminum alloy ingot having the chemical composition shown in Table 1 was subjected to homogenization heat treatment at 580°C for 3 hours, and then hot rolled. to 3.0cm thick, then cold rolled (1.0cm 1 thickness)
500℃ x O seconds (heating and cooling rate: 1000℃
/m) rapid heating and cooling was performed. It was further cold rolled to a thickness of 0.35 mm and final annealed at 300°C. Table 2 shows the material properties, formability and aging properties of the obtained plate material. The sample can was 66mmφ x 72mm by DI processing.
b (minimum can wall thickness 0.13 m■), and the can bottom shape is
As shown in the figure. In addition, the strength of the can bottom and can wall was measured using small test pieces. From Table 2, the example of the present invention has a predetermined compressive strength (3 kg/c
It can be seen that it satisfies the requirements (I112 or higher) and at the same time satisfies the inversion of the can bottom at negative pressure. However, the comparative example did not satisfy any of the requirements.

[Margin 1 below] Example 2 Using the sample material N111 (Table 1) from Example 1, the amount of inversion of the can bottom (the amount of reduction in the internal volume of the can) was varied as shown in Table 3, and the difficulty of inversion was And the internal pressure of the can after reversal was determined. As a result, as shown in Table 3, Ha within the scope of the present invention
It can be seen that No. 2 satisfies the required characteristics (no dents) for a can. Although Comparative Example &1 was easily inverted, the internal pressure of the can after inversion did not reach positive pressure (1 kg/cr12 or more), and a dent occurred in the side wall. [Blank below] (Effects of the invention) As detailed above, according to the present invention, D for non-carbonated beverages
It is now possible to reduce the thickness of the side wall, which is an issue with negative pressure cans.1
Even if the internal pressure of the can becomes negative, preferential denting of the side wall can be prevented, promoting the use of aluminum for non-carbonated beverages, and making it possible to take advantage of the features of aluminum cans, including recycling.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of the shape of the bottom of a test can. Patent applicant Takashi Nakamura, Patent attorney representing Kobe Steel Co., Ltd. Procedural amendment 1, Case description 1990 Patent Application No. 165347 2, Title of invention Aluminum alloy plate for negative pressure cans and its manufacturing method and negative pressure Case 3, Relationship with the person making the amendment Patent applicant address 1-3-18 Wakihama-cho, Chuo-ku, Kobe Name (1)
19) Kobe Steel, Ltd. 4, Agent Address: 5-358 Nishi-Nippori, Arakawa-ku, Tokyo 116 Contents of Amendment (1) “Patent Application Hei 2-” on page 4, lines 16 to 17 of the specification The description of "No." is corrected to "Patent Application No. 2150534."

Claims (3)

[Claims] (1) In weight% (the same applies hereinafter), Mn: 0.5 to 1.5
% and Mg: 0.5 to 2.0%, and further Fe: 0
．． 2-0.7%, Si: 0.1-0.5%, Cu: 0.
05-0.5% and Zn: 1 of 0.1-1.0%
In an aluminum alloy plate for a DI can containing one or more species and the remainder being substantially Al, the strength of the side wall of the can is 1.2 times or more higher than that of the bottom of the can, and the inside of the can is under negative pressure. An aluminum alloy plate for a negative pressure can, characterized in that the bottom part of the can is deformed preferentially when the bottom part of the can is deformed. (2) For a plate obtained by subjecting an aluminum alloy ingot having the chemical composition according to claim 1 to homogenization heat treatment at 550°C or higher, and then subjecting it to a combination of ordinary hot rolling, cold rolling, and intermediate annealing. By annealing the tensile strength to 18 to 25 kg/mm^2, the strength of the side wall of the DI can is more than 1.2 times higher than that of the bottom, and when the inside of the can becomes negative pressure. A method for manufacturing an aluminum alloy plate for a negative pressure can, characterized in that a material is obtained in which the bottom of the can is deformed preferentially. (3) In the DI can made of the aluminum alloy plate obtained in the claim, when the can internal pressure becomes less than 1 kg/cm^2, the can bottom deforms inside the can, and the internal volume of the can decreases by 8 to 15 ml. A DI negative pressure can body characterized in that the internal pressure becomes positive pressure (1 kg/cm^2 or more).