JPH0464797B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for manufacturing aluminum welded cans with excellent surface appearance characteristics, particularly aluminum welded cans formed with various coined patterns. BACKGROUND OF THE INVENTION Recently, aluminum cans have been increasingly used as beer cans, soft drink cans, and the like due to their light weight, appearance characteristics, and cleanliness. On the other hand, in recent years, in consideration of the general consumer's preference for luxury goods and gourmet food, designs have been added to the body wall of cans with the aim of differentiating them from other canned products, individualizing them, and making them more luxurious. There is a growing demand for cans that are provided with a variety of superior coining patterns and have further improved appearance characteristics. By the way, as a conventional aluminum can, a two-piece can produced by the Motsupara DI processing method (deep drawing and ironing method) is used. However, when manufacturing two-piece cans, it is necessary to apply a strong ironing process to the can body wall during DI processing, so coining pattern processing (embossing) is performed on the blank material before DI processing. Therefore, the coining pattern must be applied after the bottomed cylinder is created by DI processing. However, it is actually extremely difficult to apply a coining pattern to a bottomed cylinder, and for this reason, a two-piece aluminum can with a coining pattern applied to the body wall has not yet been realized. On the other hand, for steel cans, blanks are curved into a cylindrical shape and then joined together using methods such as electrical resistance seam welding, gluing, or soldering to create a cylinder, resulting in a three-piece can. Common. In order to apply a coining pattern to the can body wall in the manufacture of such three-piece cans, it is possible to apply the coining pattern to the blank state before making the cylinder. Since the surfaces are no longer flat, joining becomes difficult, and even if joining is possible, there is a problem in that sufficient airtightness cannot be obtained. Further, although it is easier to apply a coining pattern after the cylinder is made than in the case of a bottomed cylinder of a two-piece can, there are problems in terms of efficiency and economy. Problems to be Solved by the Invention As mentioned above, in two-piece cans, which are mainly applied to aluminum cans, coining pattern processing is performed on the raw material plate before cylindrical forming by DI processing, which is related to ironing processing. It is impossible to do so, and it is also difficult to apply a coining pattern after forming a cylinder.On the other hand, in the case of three-piece cans, which are often applied to steel cans, the coining pattern is applied to the raw material plate before it is made into a cylinder. There was a problem in terms of joining to make the cylinder, and there was also a problem in terms of efficiency and economy in processing the coined pattern after making the cylinder. The present invention has been made to solve the above problems, and provides a method for easily producing aluminum cans with a coined pattern on the can body wall without causing the above-mentioned problems. The purpose is to Means for Solving the Problems The inventors of the present invention have conducted extensive experiments and research to solve the above-mentioned problems, and have found that in the conventional manufacturing process of three-piece cans, a material plate with a coining pattern processed in advance is used as a cylindrical material. While it was common knowledge that joining by rolling it into a shape was considered inappropriate in terms of airtightness,
In particular, by applying ultrasonic seam welding as a joining method, it is possible to join material plates that have been processed with a coining pattern with sufficient airtightness. It was discovered that a cylinder having sufficient airtightness could be created by joining by ultrasonic seam welding, and this invention was achieved. Therefore, in the method of manufacturing an aluminum welded can with a coining pattern according to the present invention, thin aluminum plates that have been processed with a coining pattern in advance are curved into a cylindrical shape, their tips are overlapped, and the overlapping part is ultrasonically seamed. It is characterized by being joined by welding. Here, as for the aluminum thin plate which has been subjected to coining pattern processing in advance, the height (mm) of the convex part due to coining pattern processing and the area S (mm ² ) of the convex part satisfy d/√<1.0. It is preferable to use what you have inside. Function: In the aluminum welded can manufacturing method of the present invention, a thin aluminum plate 1 which has been previously subjected to various coining patterns as shown in FIG. 1 is used as a material for the can body. Here, coining pattern processing is also called embossing, and involves passing the plate material between the rolls using rolls with uneven surfaces.
This refers to a plastic working method that transfers the uneven pattern of a roll onto a plate. The pattern shape of the coining pattern formed by this coining pattern processing is not particularly limited, but the height d (mm) and area S (mm ² ) of the convex portion 4 protruding with respect to the flat reference surface 3 are d/√ It is desirable to set the value within a range that satisfies <1.0. Here, when the planar shape of the convex part 4 is a square as shown in FIG. 1, the value of √ corresponds to the length of one piece of the convex part 4. When d/√ is 1.0 or more, that is, when the height d of the convex part 4 is larger than the square root of the area S of the convex part 4, the ends of the plates are overlapped as will be explained later. When performing ultrasonic seam welding, the unevenness of the plate may not be sufficiently crushed, making welding difficult. Note that the convex portion 4 of the thin aluminum plate processed with the coining pattern refers to the portion that protrudes from the reference surface 3, which is a continuous plane in the same horizontal plane in two dimensions, and is It goes without saying that there are cases where the front side serves as the reference surface 3 and the convex portions 4 apparently protrude toward the back side. Furthermore, the upper limit of the apparent total thickness T including the height d of the convex portion is not particularly limited, but in normal coining pattern processing, the upper limit is about three times the actual thickness t of the thin plate, and generally the actual thickness It is often twice or less than t, and if T is 3t or less or 2t or less, ultrasonic seam welding can be performed simply by satisfying the condition of d/√<1.0. The thin aluminum plate 1 with the coining pattern described above is formed into a cylindrical shape by a known method such as roll forming, and both ends 5 and 6 of the thin aluminum plate 1 are overlapped as shown in FIG. , the overlapping part 7 is connected to an ultrasonic welding chip 8 and an anvil (base).
Insert between 9 and 9. Then, by applying horizontal ultrasonic vibration energy with the chip 8 while applying appropriate pressure with the chip 8, the overlapping portion 7 is solid-state welded, and the overlapping portion 7 is bonded to the tip 8 and the anvil 9 by the seam. Seam welding is accomplished by relative movement in the directions. Here, in conventional ultrasonic seam welding, simple lap seam welding with a small degree of deformation of the welded part was normally performed, but in the ultrasonic seam welding of aluminum thin plates with a coined pattern according to the present invention, It is desirable to use pine seam welding, which has a large degree of deformation in the welded part. In other words, lap seam welding, which is commonly applied in conventional ultrasonic seam welding, involves overlapping thin aluminum plates 21 and 22 to be welded with a large overlap margin, as shown in FIG. In this case, the inner part is sandwiched between the chip 8 and the anvil 9 and ultrasonic seam welding _is performed. The minimum thickness is t ₁ , and the deformation degree expressed as (t ₀ - t ₁ )/t ₀ is a small value of 5% or less, and in this case, the upper thin plate 21
Normally, only that part is deformed and a recess 24 is formed in that part. On the other hand, lap seam welding reduces the overlap of the overlapped parts and crushes both the upper and lower thin plates of the overlapped part with a large degree of deformation in an overall and symmetrical manner to form a nearly flat lap joint. In the past, such pine seam welding was performed by resistance welding, etc., but not by ultrasonic seam welding. However, the present inventors have already filed Japanese Patent Application No. 60-234808
No. 97785) proposes to increase the seam welding speed by performing pine seam welding by ultrasonic seam welding, and in the case of this invention as well, by applying pine seam welding, a coined pattern is processed in advance. The applied aluminum thin plates can be joined without any welding defects. Furthermore, to explain in detail the ultrasonic seam welding situation in the method of the present invention in the case of the above-mentioned pine seam welding, as shown in FIG. The overlap length L of the overlap part 7 is 0.5 to 4
Preferably within the range of mm, and even within that range
It is preferably within the range of 0.7 to 1.5 mm. In addition, the total effective thickness of both ends 5 and 6 of the stacked aluminum thin plates 1 is t ₀ (=2t), the thickness of the welded part after welding is t ₁ , and {(t ₀ − t ₁ )/t ₀ }×100 Ultrasonic seam welding is performed while crushing the entire overlapping portion 7 so that the actual degree of deformation expressed in (%) is a large value of 20 to 50%, resulting in a pine seam shape as shown in Figure 2B. It is desirable to form a joint. According to such ultrasonic seam welding, it is possible to completely join overlapping portions of thin aluminum plates that have been subjected to coining pattern processing, that is, thin aluminum plates that have unevenness, without impairing airtightness.
This was newly discovered by the present inventors, and although the reason has not yet been completely elucidated, it is generally thought to be as follows. In other words, in ultrasonic welding, horizontal ultrasonic vibrations are applied while applying pressure in the direction of crushing the entire overlapping portion 7, and thus crushing the unevenness caused by coining pattern processing. Vibration causes plastic flow near the joint interface, expanding the joint interface, and creating a new surface (active surface) at the joint interface.
occurs and solid phase bonding is performed. At this time, it is thought that the above-mentioned plastic flow easily crushes the unevenness caused by the coining pattern process to form a flat shape, and the flat newly formed surfaces are bonded together in sufficient close contact. In particular, when the overlapping margin L of the overlapping portion 7 is set within the range of 0.5 to 4 mm, preferably 0.7 to 1.5 mm as described above, a large degree of substantial deformation of 20 to 50% is given.
The overlapped portion 7 is crushed with a large degree of deformation, and the largest deformation occurs at the tips 5A, 6A of the overlapped ends 5, 6, forming a pine seam type joint, but at this time, the tips 5A, 6A Since it is not constrained by undeformed parts, the overlapping part 7
It is thought that both end portions 5 and 6 easily spread in the lateral direction, and that the unevenness caused by the coining pattern process is also easily crushed. Here, if the relationship between the height d and the area S of the convex part 4 of the thin aluminum plate subjected to the coining process does not satisfy d/√<1.0 as already stated,
If the stiffness of the thin plate is too strong, the unevenness caused by coining pattern processing may not be crushed during ultrasonic seam welding. Therefore, it is desirable that d/√<1.0. In addition, if the overlap margin in the overlapping part of aluminum thin plates to be ultrasonic seam welded is less than 0.5 mm,
During welding, as welding progresses, the ends of the stacked aluminum thin plates tend to become misaligned with each other, and there is a risk that seam welding may become impossible. On the other hand, if the overlap exceeds 4.0 mm, it will not be possible to sufficiently deform the tip of the thin plate in the overlapped portion, and as in the case of the conventional method shown in Figure 3, an undeformed portion will occur at the tip and due to its restraint. There is a possibility that it will be difficult to crush the unevenness caused by coining pattern processing. Therefore, it is desirable that the overlap is within the range of 0.5 to 4.0 mm. Further, if the actual degree of deformation is less than 20%, the spread in the lateral direction will be reduced and it may be difficult to sufficiently crush the unevenness. On the other hand, if the actual degree of deformation exceeds 50%, the joint may become thinner than the base material plate thickness, causing problems in terms of strength. Therefore, it is desirable that the actual degree of deformation is within the range of 20 to 50%. As mentioned above, in addition to setting the overlap margin to 4.0 mm or less so that the actual degree of deformation is 20 to 50%, measures such as increasing the pressure during welding or increasing the ultrasonic vibration energy may be taken. It is desirable to use them together. By the way, when ultrasonic seam welding is performed with a high degree of deformation of 20% or more with the overlap allowance in the range of 0.5 to 4.0 mm as described above, if the overlap allowance is close to the lower limit of 0.5 mm,
As welding progresses, the ends of the stacked aluminum sheets gradually move apart, and welding may become impossible in the latter half of welding. 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: Both ends of the aluminum thin plate that is the object to be welded,
Clamp with a load of 50 kg or more on each side of the welded area in the width direction. 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 reliably prevented. In addition, when actually applying the cylinder obtained by ultrasonic seam welding to beverage cans, food cans, etc., a bottom plate and a lid plate are attached to the cylinder. As a method, the same means as in the production of conventional three-piece cans may be applied. Furthermore, it goes without saying that the aluminum targeted by the present invention includes not only pure aluminum but also aluminum alloys. Furthermore, the thickness of the aluminum thin plate targeted by this invention is
In short, there is no particular limitation as long as ultrasonic seam welding is possible, but it is usually applicable as long as it is 1.0 mm or less, and the method of the present invention can be particularly suitably applied to seams of 0.5 mm or less. Example: JIS 5052-H38 agent with a thickness of 0.23 mm as a test material.
An aluminum alloy thin plate with a length of 120 mm and a width of 200 mm was used, and the thin plate was passed between rolls having an irregular uneven pattern formed on the surface to form a coined pattern.
In addition, the height d (mm) of the convex part of the board after processing this coining pattern
The relationship between the area S (mm) of the convex portion and the d/√ value was less than 1.0 at the maximum. Such a thin plate was rolled into a cylindrical shape, both ends of which were overlapped with an overlap margin L=1 mm, and seam welding was performed using an ultrasonic seam welder with an output of 1200 W as a welder to examine weldability. Here, weldability was determined by applying a color check liquid to the outer surface and checking whether the liquid oozed out to the back surface 24 hours later.
The results are shown in Table 1. As a comparative example, cylinders of the same size and made of the same material and having a coined pattern were prepared by electrical resistance seam welding or adhesion, and the weldability or adhesion of these cylinders was also examined in the same manner as above.

[Table] As shown in Table 1, in the case of comparative examples using conventional electrical resistance seam welding and adhesive bonding, leakage occurred at the joints of thin aluminum plates with a coined pattern, and sufficient airtightness was not achieved. However, when using the method of the present invention, no leakage occurred at the joint, and sufficient airtightness could be ensured. Effects of the Invention As is clear from the embodiments described above, according to the method of the present invention, by applying ultrasonic seam welding, a thin aluminum alloy plate that has been previously subjected to a coining pattern is rolled up and its ends are Therefore, the method of the present invention makes it possible to join welded aluminum cans with a coined pattern on the can body surface without significantly increasing costs or reducing manufacturing efficiency. It has become possible to easily obtain aluminum cans without causing damage, and it has therefore become possible to practically provide aluminum welded cans with excellent surface appearance characteristics.

[Brief explanation of the drawing]

Fig. 1 is a perspective cross-sectional view showing an example of a thin aluminum plate processed with a coined pattern used in the method of the present invention, and Fig. 2 A and B are diagrams for explaining ultrasonic seam welding in the method of the present invention. , A is a schematic sectional view showing the situation before welding, and B is a schematic sectional view showing the situation after welding. Figure 3 is a diagram for explaining conventional general ultrasonic seam welding, in which A is a schematic sectional view showing the situation before welding, and B is a schematic sectional view showing the situation after welding. be. 1...Aluminum thin plate processed with coined pattern, 4...Protrusion, 7...Overlapping part.

Claims (1)

[Claims] 1. A coining stamp characterized in that thin aluminum plates that have been previously processed with a coining pattern are curved into a cylindrical shape, their tips are overlapped, and the overlapped parts are joined by ultrasonic seam welding. A method for manufacturing a patterned aluminum welded can. 2 As the aluminum thin plate subjected to the coining pattern processing, the height d (mm) of the convex part due to the coining pattern processing
The method for manufacturing an aluminum welded can with a coined seal pattern according to claim 1, wherein the area S (mm ² ) of the convex portion is within a range satisfying d/√<1.0.