JPH0354033B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for manufacturing a can made of an aluminum alloy, and more particularly to a method for manufacturing a so-called three-piece can body in which the can body is manufactured by ultrasonic seam welding. It is something.

Conventional technology Conventionally, cans made of aluminum alloy generally include:
Many so-called two-piece cans are manufactured using the DI method, which combines deep drawing and ironing. however
When manufacturing cans using the DI method, ironing often becomes difficult if the can body is made thicker, and if the can body is made thicker, the can bottom becomes thicker than necessary, making it uneconomical. For this reason, cans manufactured using the DI method are limited to those with thin can bodies. Therefore, the two-piece can using the DI method is
Although it is widely used in applications where internal pressure is applied, such as beer and other carbonated beverages, 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, resulting in poor strength. It is considered inappropriate on the surface.

Therefore, for applications where no internal pressure is applied, it may be possible to use a so-called three-piece can in which not only the can lid but also the can bottom and can body are processed separately. 3
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, a thin aluminum alloy plate as a raw material is roll-formed into a cylindrical shape, and the circumferential ends of the can body are overlapped.
A method is known in which the overlapping portions are joined by ultrasonic seam welding.

Figure 4A shows a cross-section perpendicular to the seam direction before welding in conventional general ultrasonic seam welding in the manufacturing method for can bodies for three-piece cans made of aluminum alloy. The state of the obtained joint is shown in FIG. 4B in the same cross section. In these figures, 1 is an anvil (base) and 2 is a welding chip, in which the ends 3 and 4 of aluminum alloy sheets formed into a cylindrical shape are overlapped for seam welding, and the overlapping part is called chip 2. Anvil 1
The edges 3 and 4 of the aluminum alloy thin plates are solid-state welded by applying horizontal ultrasonic vibration energy with the tip 2 while applying appropriate pressure. Seam welding is achieved by relatively moving the aluminum alloy sheets in the length direction of the overlapping portion (and therefore in the length direction of the cylinder).

By the way, in conventional ultrasonic seam welding for general can body manufacturing, the degree of deformation of the lap joint, that is, the lap thickness before welding (total thickness of two thin plates) as shown in Figure 4 A and B Let t ₀ be t 0 , and t ₁ be the minimum thickness of the welded part after welding, and the degree of deformation expressed as (t ₀ − t ₁ )/t ₀ is said to be 5% or less, which means that ultrasonic This was considered an advantage of seam welding. Further, in this case, as shown in FIG. 4B, only the end portion 3 of the aluminum alloy thin plate above the lap joint is deformed, and a recess 5 is usually formed in that portion.

Problems to be Solved by the Invention However, in the conventional ultrasonic seam welding of aluminum alloy thin plates for manufacturing can bodies as described above, the welding speed is 1 for a plate thickness of 0.2 mm, for example.
m/min, which is much slower than other seam welding methods, such as seam welding by resistance welding for manufacturing can bodies from thin steel sheets, and therefore the welding work efficiency is extremely low, resulting in lower can manufacturing efficiency. There was a problem that the value had to be low.

This invention was made against the background of the above-mentioned circumstances, and has made it possible to perform seam welding at a much higher speed than the conventional method of manufacturing aluminum can bodies using ultrasonic seam welding. It is an object of the present invention to provide a method for manufacturing an aluminum alloy can body for a three-piece can, in which the can efficiency is significantly improved compared to conventional can bodies.

Means for Solving the Problems In order to achieve the above-mentioned object, the inventors of the present invention have carried out extensive experiments and studies, and have found that the overlapping portions of aluminum alloy thin plates to be ultrasonic seam welded after being formed into a cylindrical shape are By ultrasonic seam welding, the overlap is within a specific range, and the overlap is deformed to a degree of deformation that is unimaginable with conventional ultrasonic seam welding. It was discovered that seam welding could be performed at a much higher speed, leading to the invention.

Specifically, the method of the present invention involves forming an aluminum alloy thin plate into a cylindrical shape by roll forming,
In a method of manufacturing a three-piece can body by overlapping the ends in the circumferential direction and then joining the overlapping portions by ultrasonic seam welding, there is an overlap margin between the ends during ultrasonic seam welding. is within the range of 0.5 to 4.0 mm, and the degree of deformation of the thickness is 20 to 50 while crushing the entire overlapped part.
It is characterized by ultrasonic seam welding so that the

Function: In the method for manufacturing a can body of the present invention, first, a thin aluminum alloy plate is curved by roll forming into a cylindrical shape. As this roll forming method, a known method can be applied.

Next, the circumferential ends of the cylindrical aluminum alloy thin plates are overlapped, and the overlapping parts are ultrasonically seam welded. When overlapping the ends 3 and 4 of the thin aluminum plates, the overlapping margin L of the overlapping portion 6 should be set to 0.5~
Must be within the range of 4.0mm. And the overlapping part 6
The degree of deformation, that is, the total thickness before welding, is t ₀ ,
The thickness after welding is t ₁ , and the entire overlapped part 6 is shaped so that the degree of deformation expressed by {(t ₀ − t ₁ )/t ₀ }×100 (%) is within the range of 20 to 50%. Seam welding is performed while crushing to form a lap joint 7 as shown in FIG. 1B.

Here, as mentioned above, seam welding is performed while crushing the entire overlapping part 6 with a high degree of deformation of 20 to 50%. As is clear from FIG. 1B, the upper aluminum alloy thin plate end 3 In addition to being crushed, the lower aluminum alloy thin plate end 4
This means that the joints are crushed almost symmetrically to form a nearly flat overlapped joint, that is, a so-called pine seam-shaped joint. A seam welding method for forming a pine seam type joint with such a high degree of deformation has been used in resistance welding methods for manufacturing steel can bodies, but was completely unknown in ultrasonic seam welding. In other words, as mentioned above, in conventional ultrasonic seam welding, it is common knowledge that only the edge of the thin aluminum alloy plate on the top side is deformed with a degree of deformation of 5% or less, and this is considered to be an advantage in a sense. Therefore, it is completely inconceivable that pine seam welding could be performed by crushing both the edge of the aluminum alloy thin plate on the upper side and the edge of the aluminum alloy thin plate on the lower side as a whole with a high degree of deformation of 20% or more. (For example, see "ALUMINUM Vol.," edited by ASM, p611).

As mentioned above, 20~4 mm width overlap area
By performing pine seam welding with a high degree of deformation of 50%, seam welding can be performed at a much higher speed than conventional ultrasonic seam welding. This fact was discovered through detailed experiments by the present inventors, and the reason is thought to be as follows. That is, in the above-mentioned FIG. 1, when pressure is applied while applying ultrasonic vibration to the overlapped part 6, in the method of this invention, the overlapped part 6 is crushed with a large degree of deformation, and the overlapped aluminum The largest deformation occurs at the tips 3A and 4A of the aluminum alloy thin plate ends 3 and 4, forming a pine seam joint, but at this time, the tips 3A and 4A of the aluminum alloy thin plate ends 3 and 4 are constrained by the undeformed portions. Therefore, in the overlapping portion 6, both the upper and lower ends easily expand laterally, and as a result, the bonding interface 8 also easily expands, so that new surfaces (active surfaces) easily appear at the bonding interface 8. , it is thought that solid phase bonding becomes easier to perform. Particularly in ultrasonic seam welding, surface oxides, etc. at the interface are simultaneously removed by ultrasonic vibration, making joining even easier.

On the other hand, in so-called lap seam welding by conventional ultrasonic seam welding as shown in FIG. 4, the deformation is mainly limited to the vicinity of the welded part at the end of the upper thin plate, and is constrained by undeformed parts from the periphery. Therefore, the lateral expansion during deformation is extremely small, and therefore the expansion of the bonding interface 8 is also small, so the appearance of new surfaces at the bonding interface 8 is also small, and therefore bonding is performed mainly by the ultrasonic vibration action described above. Therefore, the ease of joining was inferior to that of the present invention, and it is considered that joining at high speed was difficult.

If the overlap margin at the overlapping part of the aluminum alloy thin plate ends is less than 0.5 mm, the overlapped aluminum alloy thin plate ends will tend to shift during welding as welding progresses, and seam welding will not be possible. There is a strong possibility that it will be impossible. On the other hand, the overlap is 4.0
If it exceeds mm, it will not be possible to sufficiently deform the end of the thin plate in the overlapping part, and as in the case of the conventional method shown in Fig. 4, an undeformed part will be created at the end, and the restraint will cause the thin plate to deform by more than 20%. This makes it difficult to achieve high deformation, making it impossible to obtain a pine seam-shaped joint, and therefore making it impossible to achieve the high-speed welding that is the objective of this invention. Therefore, in this invention, the overlap distance is set to 0.5 to 4.0 mm.
was within the range of

Furthermore, if the degree of deformation is less than 20%, the spread in the lateral direction will be reduced, and the appearance of new surfaces at the joint interface will be reduced, making high-speed welding difficult. On the other hand, the degree of deformation is 50%
If it exceeds the thickness of the base material, the joint will become thinner than the base material plate thickness, causing problems in terms of strength. Therefore, in this invention, the degree of deformation is set within the range of 20 to 50%.

As mentioned above, it is important to keep the overlap to 4.0 mm or less so that the degree of deformation is 20 to 50%, but it is also important to increase the pressure during welding or increase the ultrasonic vibration energy. It is desirable to use methods such as

By the way, as mentioned above, when a cylinder is ultrasonically seamed welded with a high degree of deformation of 20% or more with an overlap margin in the range of 0.5 to 4.0 mm, if the overlap margin is close to the lower limit of 0.5 mm, the overlap will occur as welding progresses. The ends of the thin aluminum alloy sheets gradually shift away from each other, and welding may become impossible in the latter half of the welding process. In order to prevent this, it is preferable to apply the following methods A, B, and C.

A: Estimate the expected amount of deviation, and according to the amount of deviation, overlap the parts in advance so that the overlap margin at the welding end is larger than that at the welding start. In this case, the increase in the overlap of the weld end with respect to the weld start end is usually 0.5 to 2.0 mm per 250 mm of weld length.
It is preferable to keep it at a certain level.

B: The welding end portion is temporarily attached in advance by ultrasonic spot welding or the like.

C: The edge of the aluminum alloy thin plate that is the object to be welded is weighed 50 kg on each side in the width direction of the welded part.
Clamp with the above load.

Here, any one of these methods A to C may be applied alone, but if two or more are used in combination, misalignment can be more effectively prevented.

However, even if method A is used as described above, misalignment may occur within a range of about 20 cm from the weld end, and even if method C is used to completely clamp the weld, the clamped part and welded part may be misaligned. Misalignment may occur with buckling between the two. On the other hand, at the start of welding, insufficient ultrasonic vibration energy is input, resulting in insufficient joining, and conversely, if sufficient input is applied, the end becomes excessively deformed due to its free end, resulting in microscopic Cracks may also occur.
In this way, weldability problems may occur at the welding start and end points, so when actually manufacturing can bodies, extremely long cylinders are continuously formed and continuously ultrasonic seam welded. It is then desirable to cut the can body into the required length.

Note that the composition of the aluminum alloy used in the method of this invention is not particularly limited;
3004 alloy, which has traditionally been used for can bodies,
3000 series alloy (Al-Mn series alloy) or 5182
Alloys, 5000 series alloys (Al-Mg alloys) such as 5052 alloy, etc. can be suitably used. Further, the thickness of the aluminum alloy thin plate used in the method of the present invention is not particularly limited as long as it can be ultrasonic seam welded, but it is suitably applicable to a thickness of 0.5 mm or less.

ExamplesExample 1 JIS A5052P-H38 material with a thickness of 0.23 as a test material
After forming a cylindrical shape with a diameter of 50 mmφ and a length of 120 mm using roll forming,
Ultrasonic seam welding was performed on the overlapping portions of both ends in the circumferential direction using an ultrasonic welding machine with an output of 1200 W under the conditions shown in Table 1 to examine weldability. The results are shown in Table 1. Weldability was determined to be good if the welded joint did not peel off when the welded joint was bent 180°.

■■■ Tortoise shell [0024] ■■■ As is clear from Table 1, the overlap is 0.5 to 4.0.
20 mm and the welding force is 150Kg.
In the case of the present invention, which provides a degree of deformation of more than %, no peeling of the welded part occurred even at a welding speed of 10 m/min. On the other hand, in a comparative example in which the overlap width was set to exceed 4.0 mm or the welding pressure was reduced, and the degree of deformation was set to 5%, peeling occurred at a welding speed of 1 m/min. From these results, it can be seen that according to the method of the present invention, the welding speed can be significantly increased compared to the conventional method. In addition, in a comparative example in which the overlap was less than 0.5 mm at the starting end, welding became impossible due to misalignment during welding.

Example 2 The sample material was JIS A5182-H38 material with a thickness of 0.2 mm.
Using an aluminum alloy thin plate coil with a width of 157mm,
As shown in FIGS. 2 and 3, a continuous cylinder was created by continuous forming and continuous ultrasonic seam welding. That is, in FIGS. 2 and 3, the coil 9
Forming rolls 10A, 10A'; 10B, 10
B'; Continuously supplied to a roll forming machine consisting of 10C and 10C' to form it into a cylindrical shape, and while holding the cylinder with clamp rolls 11 and 11', welding tip 2 and anvil 1 produce a maximum output of 1200 W. ,
A continuous cylinder was created by ultrasonic seam welding under the conditions of an overlap margin of 1.0 mm, a welding speed of 8 m/min, and a degree of deformation of the welded part of 35%, and then cut to 120 mm by cutting machine 12.
Each piece was cut into a cylinder 13 for the can body with a length of 120 mm.

As a result of examining the welded portion of this can body cylinder 13 in the same manner as in Example 1, it was found that no peeling occurred in the welded portion, indicating good weldability.

Effects of the Invention As is clear from the above-mentioned embodiments, the three advantages of this invention are as follows.
According to the method for manufacturing aluminum alloy can bodies for piece cans, the welding speed in ultrasonic seam welding after roll forming into a cylindrical shape is significantly faster than when conventional ultrasonic seam welding is applied. Therefore, the seam welding work efficiency can be significantly improved compared to the conventional method, and the can body manufacturing efficiency can be significantly improved compared to the conventional method.

[Brief explanation of drawings]

1A and 1B are diagrams for explaining the ultrasonic seam welding method applied to the can body manufacturing method of the present invention, in which A is a schematic cross-sectional view showing the situation before welding, and B is a schematic cross-sectional view showing the situation before welding. Fig. 2 is a schematic cross-sectional view showing the situation of Example 2, in which a long coil is continuously subjected to roll forming and ultrasonic seam welding by applying the can body manufacturing method of the present invention. A schematic perspective view, and FIG. 3 is a longitudinal sectional view taken along the - line in FIG. 2. Figures 4A and 4B are diagrams for explaining the conventional general ultrasonic seam welding method;
B is a schematic sectional view showing the situation before welding, and B is a schematic sectional view showing the situation after welding. 1... Anvil, 2... Welding tip, 3, 4...
... Aluminum thin plate, 6 ... Overlapping part.

Claims (1)

[Claims] 1. A thin aluminum alloy plate is formed into a cylindrical shape by roll forming, the circumferential ends of which are overlapped, and then the overlapped parts are joined by ultrasonic seam welding to form a three-piece product. In the method of manufacturing can bodies, the overlap between the edges during ultrasonic seam welding is set within the range of 0.5 to 4.0 mm, and the degree of deformation of the thickness is 20 to 50 mm while crushing the entire overlapped part. %
A method for manufacturing an aluminum alloy can body for a three-piece can, characterized by ultrasonic seam welding so as to achieve the following.