JPS62263836A - Manufacture of aluminum alloy made joining can shell body - Google Patents

Abstract

PURPOSE:To improve a flange cracking resistance by using the Al alloy sheet having a specific elongation % as the blank and executing a local heating before or after joining the overlapping part thereof. CONSTITUTION:What has the elongation property of 5-20% range is used for the Al alloy sheet 5 of as the blank and the four corner parts 5a, 5b, 5c, 5d of the sheet 5 which are prior to the joining only are subjected to a heat softening treatment locally. They are then made in a cylindrical shape with their curving by a roll forming, etc. and the opposing side parts are joined by overlapping. Or only the piling junction parts 2a, 2b of after joining are softened by local heating. In this case, the heat softening treatment is performed so as to satisfy the equation I respectively. A flange cracking is apt to cause on the overlapping part 2, so in this way the flange cracking resistance is improved and the production cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for manufacturing cans made of aluminum alloy, and in particular to a method for manufacturing cans made of aluminum alloy.
The present invention relates to a method for manufacturing a flanged can body for a piston can.

BACKGROUND OF THE INVENTION Conventionally, many aluminum alloy cans are so-called two-piece cans manufactured by a DI method that combines deep drawing and ironing. However, when producing cans using the DI method, ironing often becomes difficult when the thickness of the can body is made thicker, and if the can body is made thicker, the can bottom becomes thicker than necessary, making it uneconomical. , so DI
Cans manufactured using this method are limited to those with thin can bodies. Therefore, DI type two-piece cans are widely used in applications where internal pressure is applied, such as beer and other carbonated beverages, but they are not used in applications where internal pressure is not applied, such as coffee beverage cans, non-carbonated beverage cans, and food cans. , the wall thickness of the can body is too thin and is considered unsuitable from the viewpoint of strength.

Therefore, for applications where internal pressure is not applied, it is conceivable to use a so-called 3-piece can in which not only the can lid but also the can bottom and can body are processed separately. Three-piece cans allow the thickness of the can bottom and can body to be changed individually, and are relatively easy to process.

By the way, as a method for manufacturing the can body of a three-piece aluminum alloy can, it is possible to curve a thin aluminum alloy plate as a material by roll forming into a cylindrical shape, and then join the opposing sides by welding or welding. ing. In this case, the thickness of the 3-piece can generally ranges from 0.1 to 0.
Since it is relatively thin at 3 am, it is usually formed into a cylindrical shape by roll forming or the like as described above, and the opposing sides are overlapped and joined as a lap joint or matshu seam joint. After the overlapping parts are joined in this manner, flanges for attaching a can lid are formed at both open ends thereof. The flange forming process includes a roll forming method in which the open end of the can is pressed against a roll and the can is rotated or a roll is rotated in the circumferential direction of the can, and a die method in which the open end of the can is pressed against a die. .

Problems to be Solved by the Invention As mentioned above, when the body of a three-piece aluminum alloy can is manufactured by joining, the joint is usually a lap joint or a matshu seam joint. As shown, in the joint 2 of the can body 1, there is a step d equal to or slightly smaller than the thickness of the plate.

On the other hand, when attaching the can lid and can body to the can body after joining, it is normal to apply seaming, so after joining as described above, the upper and lower open ends 3 are attached as shown in Figure 5. Apply flange processing.

In this flange processing, cracks may occur in the joint 2 due to the step d of the joint 2 as described above. In other words, when flanging a cylindrical can body, not only tensile-compressive stress in the plate thickness direction but also tensile stress in the circumferential direction occurs, and especially in the joint 2 as described above, as shown in FIG. As shown in FIG. 2, stress concentration occurs at a portion 23.24 that contacts the end portion 21.22 of the stacked plates, and cracks may occur in that portion 23.24.

A method for preventing general flange cracking during flange processing of the body of a 3-piece can has already been proposed in Japanese Patent Application Laid-Open No.
As shown in Japanese Patent No. 58062, a method has been proposed in which the entire portion of the can body that is to become the open end (the portion to be flanged) is heated and softened in the form of a band before the can body is formed and joined. ing. However, this proposed method does not specifically focus on the level difference at the joint, but is aimed at preventing cracks during flange processing in general.
In order to heat the entire part of the can body that is to become the open end,
The heat input tends to be large, and the aluminum alloy has good heat conduction, so not only the parts where flange cracks are likely to occur, but also the other parts soften, reducing the strength of the can. There is a problem that it is easy to run out of. To avoid this, it may be possible to apply forced cooling to areas other than those required, but in that case, new problems such as complicating the equipment and impairing workability will arise.

On the other hand, in the manufacture of can bodies for two-piece aluminum alloy cans, DI is used to prevent common flange cracks.
A method of heating and softening the entire open end of the can body after processing is disclosed in JP-A-53-I'1338 or JP-B-59.
Although this method is proposed in Japanese Patent Application Laid-open No. 52-45733, when this method is applied to the manufacture of a can body for a three-piece can, there are problems similar to those of the method of Japanese Patent Application Laid-Open No. 52-58062.

This invention was made with the above-mentioned circumstances in mind, and taking into consideration the fact that flange processing cracks are likely to occur particularly at the joint part in the manufacture of jointed can bodies, the present invention has been developed in a way that does not reduce the strength of the can body and is simple. It is an object of the present invention to provide a method for manufacturing a joined can body made of aluminum alloy, which prevents flange processing cracks from occurring.

Means for Solving the Problems In order to achieve the above-mentioned objective, the inventors of the present invention have conducted extensive experiments and studies, and have found that the material used is an aluminum alloy thin plate whose elongation is within a predetermined range, and lap jointing is performed. The above purpose is achieved by locally heating and softening only the required portions before or after joining the joint so that the required elongation according to the size of the step formed in the joint can be ensured during flange processing. They discovered that it was possible to achieve this, and came up with this invention.

That is, the method of the first invention involves bending a rectangular aluminum alloy thin plate into a cylindrical shape, overlapping two opposing sides,
After joining the overlapping parts, both open ends are flanged to produce a flanged joint can body made of aluminum alloy, using an aluminum alloy thin plate with an elongation in the range of 5 to 20%. , and before joining the overlapping parts, the four corner parts of the aluminum alloy thin plate are locally heated and softened so as to satisfy the following formula.

El/cJ≧80 (%/mm) However, El: Elongation of the heated part after heating (%) d: Difference in thickness of the lap joint (m) In addition, the method of the second invention uses a rectangular aluminum alloy thin plate. When manufacturing a flanged can body made of aluminum alloy by bending it into a cylindrical shape, overlapping two opposing sides, joining the overlapping parts, and then flanging both open ends, we decided to An aluminum alloy thin plate with an elongation within the range of 5 to 20% is used, and after joining the overlapping parts, both ends of the overlap joint are locally heated and softened so as to satisfy the above formula, and then It is characterized by being subjected to flange forming afterwards.

Operation As shown in FIG. 1, the method of the first invention locally applies only the four corner portions 5a, 5b, 5G, and 5d of the rectangular aluminum alloy thin plate 5, which is the raw material, from the front side or the back side at the stage before joining. is subjected to heat softening treatment. Thereafter, it is curved into a cylindrical shape by roll forming or the like, and the opposing sides are overlapped and joined to obtain the joined can body 1. In the state after joining, the parts 5a to 5d which have been heat-softened as described above are located at both ends 2a and 2b of the lap joint part 2, and these parts should be subjected to subsequent flange processing, respectively. Corresponds to a part of a part. Therefore, in the case of the method of the first invention,
At the stage before joining, the four corners of the rectangular aluminum alloy thin plate 5
The heating and softening treatment of a to 5d means that the portions that are to become both ends of the lap joint 2, in other words, the entire circumference of both ends of the can body to be flanged, especially the portion that is to be the joint. This means that only the material is subjected to heat softening treatment.

As already mentioned, in the case of a joined can body, cracking during flanging is particularly likely to occur at the overlapped joint among the circumferences of both open ends to which flanging is applied. Flange processing cracks can be prevented by preheating and softening the part, especially the part that will become the lap joint.

On the other hand, in the method of the second invention, as shown in FIG.
Heat softening treatment is applied locally to the can from the front or back side in the axial direction of the can. Both end portions 2a and 2b of the overlapping joint portion 2 are
As already mentioned, each of the two open ends of the can body 1 to be flanged occupies a part of the ends, and among the open ends, these are the parts where flanging cracks are most likely to occur. As with the method described above, cracking due to flange processing can be effectively prevented.

As mentioned above, in both the methods of the first invention and the second invention, the entire part to be flanged is not heated, but the part to be flanged is particularly heated to prevent flange cracking. Since only the easy overlap joints (or equivalent parts) are locally heated, less heat is required, and there is less risk of reducing the strength of parts other than those that require heating and softening. A simple method like this will suffice.

Here, the elongation of the aluminum alloy thin plate used as the material is 5%.
If the ductility is less than 20%, the ductility of the base plate is too low, and flanging cracks are likely to occur in the parts that are not subjected to heat softening treatment, that is, the parts other than the lap joints. For materials with such elongation, the elongation at the lap joint is inherently large, so even if heat softening treatment is performed, no further improvement in ductility can be expected.
Moreover, in the case of such a large elongation, the strength of the base plate is usually low, making it impractical. Therefore, the elongation of the aluminum alloy thin plate used as the material must be within 5 to 20%.

The composition of the aluminum alloy is not particularly limited, and may include 3000 series alloys (Al-Mn alloys) such as 3004 alloy, which have been conventionally used for cans, or 5000 series alloys such as 5182 alloy (△ !-MCI alloy), etc. can be used.

In addition, specific joining methods for joining the overlapping parts after forming rectangular aluminum alloy thin plates into a cylindrical shape include bonding using adhesives, ultrasonic welding, electric resistance seam welding, and electric resistance matshu seam welding. is applicable and is not particularly limited. However, in the case of bonding, if heat softening treatment is performed after bonding, there is a risk that the adhesive will melt or deteriorate. It is preferable to apply it. On the other hand, in the case of welding, heat softening treatment may be performed either before joining (first invention) or after joining (second invention), but if there is a risk of hardening during welding, heat softening treatment may be performed after joining (after welding). It is preferable to perform treatment.

As a specific heating means for the heat softening treatment, any means such as gas burner, laser, high frequency induction heating, etc. may be used, and either method requires spot-like local heating, so it is extremely easy to carry out. However, it is preferable to use simple and inexpensive burner heating.

The degree of heat softening treatment is determined by the elongation E of the heat treated part after heating.
l<%) and the level difference d(am) of the overlapping joint portion must be determined so as to satisfy Fl/d≧80(%/IrlIr1). That is, the heat softening treatment is performed so that the elongation El corresponding to the step d of the overlapped joint is reduced to 17.

These conditional expressions were derived through experiments by the inventors, and if the above conditional expressions are not satisfied, flange machining cracks are likely to occur at the lap joint; For the first time, the effect of preventing flange cracking can be improved.

In this way, the jointed can body obtained by locally applying heat softening treatment to predetermined areas before or after joining effectively prevents flange cracking during flange processing, and also reduces strength. There are also few.

Example [Example 1] Phosphoric acid chromic acid treatment (metallic chromium fi20
mg/TIt), made of JIS A 5182 alloy H38 material and JIS A 3004 alloy To118 material, thickness 0.23 m, width 20 (1 m, length 130 m).
Two kinds of aluminum alloy thin plates were prepared, and the four corners of each thin plate were subjected to heat softening treatment from the front side using an oxygen-acetylene burner under various conditions shown in Table 1.

After that, each thin plate is formed into a cylindrical shape by roll forming,
A can body was obtained by applying brimer coating to both sides and disposing a polyamide adhesive between the overlapping edge parts, then melting the adhesive, and cooling and solidifying the adhesive under pressure.

Both open ends of the can body thus obtained were flanged using a roll flancher, and the flanging properties were examined. The results are also shown in Table 1.

In addition, test pieces were cut from both open ends of the can body produced under the same conditions as the can body produced as described above, and a local elongation test of the lap joint was conducted to determine the elongation El ( %) was determined, and the level difference d (InIn) was also investigated to determine the value of El/d.

The results are also shown in Table 1.

In addition, as a comparison material, JIS where the elongation of the base plate is less than 5%
Table 1 also shows the case where a thin plate of A 3003 alloy H alloy material was used.

[Example 2] The test material was a plate made of JIS A 5052 alloy 838 material (elongation 8%) with a thickness of 0.3 m, a width of 200 m, and a length of 130 m.
After preparing aluminum alloy thin plates with a diameter of 1.5 m and forming them into a cylindrical shape by roll forming, ultrasonic seam welding was performed on the overlapped parts using an ultrasonic welding machine with an output of 1200 W under the conditions shown in Table 2 to form a can. Got the body.

Both ends of the welded portion of this can body were locally heated from the front side using an oxygen-acetylene burner under various conditions shown in Table 2. Thereafter, both open ends of this can body were flanged using a roll flancher, and the flange crackability was examined. The results are shown in Table 2.

In addition, test pieces were cut from both open ends of a can body (after local heating) produced under the same conditions as the can body produced as described above, and a local elongation test was performed on the lap joint. Find the elongation El (%) of the part) and the step d
(m) was investigated and the value of El/(j was determined. The results are also shown in Table 2.

As is clear from Tables 1 and 2, when local heat treatment is performed before bonding and bonding with adhesive is performed (
In both Example 1) and the case where local heat treatment was performed after joining by ultrasonic seam welding (Example 2), local heating was performed so that the value of El/d was 80%/or higher. In this case, it was found that flange cracking did not occur and the flange formability was excellent. On the other hand, in both the comparative example where the El/d value was less than 80%/# due to insufficient heating time even if local heat treatment was performed, and the comparative example where local heat treatment was not performed, flange cracking occurred. The problem occurred at the step part of the overlap joint.

In Table 1 of Example 1, the comparative example using 3003 alloy H alloy material is an example in which the elongation of the original plate was less than 5%.
In this case, flange cracking occurred in the base material other than the lap joint. From this, it can be seen that in the case of the method of this invention, the condition that the elongation of the base plate is 5% or more is required.

Effects of the Invention According to the method for manufacturing a bonded aluminum alloy can body of the present invention, it is possible not only to obtain a bonded can body with excellent flange resistance and resistance to flange cracking during flange processing, but also to be able to undergo heat softening treatment. Because it only needs to be performed spot-on in a limited local area, the process is simple and workability is good, and an inexpensive and simple gas burner etc. can be used as a heating source, and the heat treatment is limited to local areas. Therefore, there is no risk that the strength of the entire can body will decrease, and cooling around the heating part is not required, so there is no risk of increasing equipment costs for cooling or reducing workability.

Therefore, according to the method of the present invention, it is possible to simply and easily obtain a joined can body with excellent flange resistance without causing a decrease in strength.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the parts to be heat-softened in the method of the first invention, FIG. 2 is an explanatory diagram to show the parts to be heat-softened in the method of the second invention, and FIG. 3 is a general diagram. FIG. 4 is a cross-sectional view showing an enlarged overlap joint of the can body in FIG. 3, and FIG. 5 is a vertical cross-sectional view showing a flanged can body. Ru. 1...Can body, 2...Overlap joint, 2a, 2b
. . . Both end portions of the lap joint, 5. Aluminum alloy thin plate, 5a to 5d. Four corner portions of aluminum alloy thin plate. Applicant Sky Aluminum Co., Ltd. Daiwa Seikan Co., Ltd. Agent Patent Attorney Yutaka 1) Hisashi Take (and 1 other person) '2t) Figure 4

Claims (2)

[Claims] (1) A rectangular aluminum alloy thin plate is curve-formed into a cylindrical shape, two opposing sides are overlapped, and after the overlapping parts are joined, both open ends are flanged to form an aluminum alloy flanged joint. In manufacturing the can body, we use thin aluminum alloy sheets with an elongation range of 5 to 20%, and before joining the overlapping parts,
A method for manufacturing a flanged aluminum alloy jointed can body, comprising locally heating and softening the four corner portions of an aluminum alloy thin plate so as to satisfy the following formula. El/d≧80 (%/mm) However, El: Elongation of heated part after heating (%) d: Difference in thickness of lap joint (mm) (2) A rectangular aluminum alloy thin plate is curved into a cylindrical shape, two opposing sides are overlapped, and after the overlapping parts are joined, both open ends are flanged to form an aluminum alloy flanged joint. To manufacture the can body, use aluminum alloy thin plates with an elongation within the range of 5 to 20%, and after joining the overlapped parts, both ends of the overlapped joints should be made so that the following formula is satisfied. 1. A method for manufacturing a flanged aluminum alloy jointed can body, which comprises locally heating and softening the aluminum alloy, followed by flange forming. El/d≧80 (%/mm) However, El: Elongation of heated part after heating (%) d: Difference in thickness of lap joint (mm)