JPS6239054B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for manufacturing an aluminum can body,
More specifically, the present invention relates to a method for manufacturing a three-piece aluminum can body in which side seams of the body are joined with an organic adhesive. (Prior Art) A relatively large capacity (for example, 1 to 5 liters) aluminum (herein referred to as aluminum including aluminum alloy) can body (for example, the body is expanded into a barrel shape), The side seams of the body are coated with organic adhesive (e.g. nylon 11 or 1).
2 or a copolymer or blend mainly composed of these materials, etc.), the bottom and the lid (in this specification, the bottom and the lid are collectively referred to as the end plate) are joined together, or lap-seamed, to form the body. Many of them are manufactured by joining the parts by double seaming. In this case, the size of the can body is relatively large,
Because the rigidity of aluminum is relatively lower than that of steel (for example, tin), a relatively thick body plate, for example, 0.2 to 0.5 mm, is often used. Therefore, as shown in Fig. 1, for example, the double seam part 1 corresponding to the side seam becomes thicker than the other double seam part 2 by approximately twice the thickness of the shell plate. Therefore, the stepped portion 3 becomes larger, and during double seaming work, the seaming roll (not shown) jumps around the stepped portion, so that sufficient pressing force is not applied near the stepped portion 3, and the seaming becomes loose. Furthermore, the end surface 5a of the inner body plate 5 and the outer body plate 6 of the overlapping portion with the end plate 4 are
The gaps 7 and 8 formed by the end surface 6a of the tube also become large, and there is a problem in that the liquid content or gas (for example, carbon dioxide gas) is likely to leak through these gaps (so-called micro leakage). In addition, in FIG. 1, 9 is an organic adhesive. In order to solve the above problems,
Publication No. 139588 discloses that at least the inner end of the can material is plastically deformed over its entire length into a slanted surface, and the organic adhesive on the outer end of the can material swells up and forms the inner end surface. A wrap-seam can body has been proposed in which the can body is continuous and integrated with an organic adhesive at the inner edge. However, in this case, only the ends of the can material are plastically deformed into the sloped parts, so the overall thickness of the double seam part at the lap seam part is almost the same as the conventional thickness. Therefore, when the organic adhesive is coated in the same manner as in the past, relatively large voids still occur. Therefore, in order to reduce this gap, a raised portion of organic adhesive is formed. Formation of this raised portion of organic adhesive poses a problem in that it requires a very complicated and unproductive process. In addition, since the slope part is formed over the entire length of the can material, the volume of the plastically deformed part becomes large.
Therefore, the plastic deformation energy becomes relatively large, resulting in a problem that the amount of power consumed for forming the slope portion becomes relatively large. (Problems to be Solved by the Invention) The present invention provides a double seam portion corresponding to a side seam portion by adding a relatively simple process, high productivity, and relatively low power consumption. An object of the present invention is to provide a method for manufacturing a wrap-seam aluminum can body in which microleakage is less likely to occur due to voids in the parts. (Means for Solving the Problems) The method for manufacturing an aluminum can body of the present invention includes overlapping opposing edges of aluminum blanks,
A method for producing an aluminum can body in which an end plate is double-sealed to a body part that is joined via an organic adhesive to form a side seam, the method comprising double-sealing the end edge of an aluminum blank. A feature is that the portion corresponding to the tightening portion is made thinner than other portions of the aluminum blank by coining processing. (Function) The additional process for the conventional manufacturing method for lap seam aluminum cans involves coining the portion of the edge of the blank that corresponds to the double seam, which is to become the side seam. Therefore, it should be made thinner than other parts of the blank. This coining process is relatively simple and has high productivity. In addition, because the coining process thins only the part corresponding to the double seam part of the edge, the volume of the plastically deformed part for thinning is small, so it is difficult to form a thin part. That is, the power consumption required for coining processing is relatively small. By adding the above simple steps, even if a relatively thick aluminum blank is used, the height of the stepped portion 25 formed at the double seam portion corresponding to the side seam portion can be reduced as shown in Fig. 5. As shown in the figure, it is possible to prevent seaming defects due to insufficient pressing force at the stepped portion and the vicinity thereof due to the jumping of the seaming roll during double seaming, and furthermore, it is possible to prevent Since the voids in the parts become smaller, micro leakage of the aluminum can can be prevented. (Example) The present invention will be described below with reference to the drawings. In FIG. 2, an aluminum can body 10 manufactured by the method of the present invention includes a body portion 11, a lid portion 12,
and the bottom part 13. The body part 11 has a side seam part 14, and the body part 11, the lid part 12, and the bottom part 13 are joined by a double seam part 15. In this embodiment, the body portion 11 is expanded to have an octagonal cross section. As shown in FIG. 4, the side seam 14 is overlaid and joined by thermal fusion of organic adhesive layers 16a and 16b. In addition, the side joint part 14
In FIG. 3, which shows the state of the portion corresponding to the double seaming part before double seaming, 18 and 19 are as follows.
The inner end edge and outer end edge of the overlapping portion 17, respectively, are approximately larger than the portion 11a (hereinafter referred to as the main portion) other than the portion corresponding to the double seaming portion of the end edge of the body portion 11. It is thin with uniform thickness.
(However, the vicinity of the end surfaces 18a and 19a may be tapered). Although not shown, the surface of the main body portion 11a that becomes the inner surface of the can (the lower surface in FIG. 3)
is usually coated with a corrosion-resistant coating (for example, a baked coating of phenol epoxy paint), and in FIG. covered. However, if there is no risk that the aluminum will be corroded by the contents, it is not necessary to form these coating layers (coating film and adhesive layer). Further, the organic adhesive layers 16a and 16b that join the overlapping portion 17 may also be only one of the layers. In FIG. 4 showing a portion 20 of the double seam portion 15 corresponding to the side seam portion 14, 21 is a cover hook portion, 22 is a body hook portion, and 23 is a portion commonly called a countersink portion. Note that in this figure, illustration of the sealing compound applied to the inner surface of the curled portion of the lid portion 12 is omitted. In this specification, the portions of the edge portions 18 and 19 corresponding to the double-sealed portions refer to the portions of the edge portions that are opposite to or opposite to the body hook portion 22 and the countersink portion 23 (located at the side seam portion 14a). Inner edge 1
8 and outer edge 19). As shown in FIG. 5, the height of the stepped portion 25 (portion 20 The difference between the maximum wall thickness of the portion 15a and the wall thickness of the portion 15a) is desirably 0.3 mm or less in order to prevent the above-mentioned jumping phenomenon of the seaming roll. The thicknesses of the inner edge portion 18 and the outer edge portion 19 are preferably approximately equal, and are preferably set to a thickness that satisfies the above-mentioned desirable conditions, depending on the thickness of the trunk main portion 11a. In this case, the volume of the void 26 formed with the end surfaces 18a and 19a of each edge portion 18 and 19 as one side also becomes smaller, and the portion 20
In addition, the stepped portion 25 is sufficiently pressed by the seaming roll, and micro leakage is prevented. Further, the end surface 19a is the stepped portion 1 of the inner edge portion 18.
8b (in Fig. 3, the angle of the step base is 90 degrees, but it may be a larger obtuse angle) or slightly more (for example, 0.1 mm) on the overlapping part 17 side. It is desirable to be located closer to the Main body portion 1 from step base 18b
1a side, the height of the stepped portion 25 becomes large, which tends to cause the seaming roll to jump. On the other hand, if it is located too close to the overlapped portion 17 side (that is, if the distance 26 becomes large, easily causing micro leakage, and the body 1
This is because a thin portion with weak mechanical strength is locally formed in the side joint portion 14 of the first side. Similarly, it is desirable that the end surface 18a be located at a position corresponding to the step base 19b of the outer edge portion 19, or slightly closer to the overlapping portion 17 than that. Note that the width of the overlapping portion 17 (ie, the joint portion) is usually about 3 to 8 mm, particularly preferably about 5 mm. The aluminum can body 10 as described above is manufactured as follows. As shown in FIG. 6, portions 18'' and 19''(18'' and 1
9'' are parts of the inner edge and outer edge, respectively) are thinned to a predetermined thickness by coining processing, and then the protruding portion and cut-off corner portion 28' are cut off. Then, the edge portion is heated to a temperature higher than the melting point or softening point of the organic adhesive by high frequency heating or burner heating, and then an organic adhesive is applied to the edge portion by a conventional method. From the viewpoint of adhesive strength, it is preferable to form a primer coating film such as a phenol epoxy baked coating film on at least the edge portion to be heat fused before heat fusion. After that, the opposing end edges of the blanks 27 or 27' are overlapped, the overlapped parts are heated, and the overlapped parts are bonded with the organic adhesive to form the body part 11.
form. Next, the body portion 11 is expanded as shown in FIG. Thereafter, after forming a flange, the bottom part 13 is double-sealed using a conventional method, and then the contents are filled, and then the lid section 12 is sealed by double-sealing using a conventional method, thereby obtaining the aluminum can body 10. . Note that the above-mentioned expanding process does not necessarily need to be performed depending on the use of the can body. A specific example will be explained below. A rectangular aluminum alloy plate with a phenol epoxy baked coating (2 μm thick) formed on both sides of aluminum alloy (JIS3004) with a thickness of 0.34 mm, a body length of 260.70 mm in the height direction, and a circumferential length of 384.70 mm. 4 was coined, and the protruding portions and corner portions 28' were cut to produce aluminum blanks 27' having the shapes shown in FIGS. 6 and 7. Next, the edges along portions 18'' and 19'' were subjected to high frequency heating to heat-seal a 40 μm thick nylon 12 film. Parts 18″ and 19″ thickness 0.17
mm, body height direction (vertical direction in the figure) length 21 mm, circumferential direction length 5 mm, long side (circumferential direction) length across the right angle of cut corner 28' 12.0 mm, and short side length Sao
It was set to 2.20mm. After the end edges that have been rolled into a cylindrical shape and reheated are overlapped, they are hammered with a cooling hammer (the hammering surface of the hammer has a shape that corresponds to the end edge), resulting in double winding. A cylindrical body was manufactured in which the portion corresponding to the tightening portion had a side joint portion 14 having a structure as shown in FIG. In this case, the distance x is
It was set to 0.1mm. Next, the cylindrical body is expanded by a method of expanding a mold consisting of a plurality of split molds to form the body part 11 having the shape shown in FIG. It was tightened. The can body thus obtained was filled with 3000 c.c. of aqueous sodium bicarbonate solution mixed with a red dye, and then the lid portion 12 was double-sealed by a conventional method to produce an aluminum can body 10. The height of the stepped portion 25 was 1.8 mm. The internal pressure at room temperature (20°C) was 2.5 Kg/cm ² . On the other hand, for comparison, a conventional aluminum can body was fabricated in the same manner as above except that portions 18'' and 19'' were not thinned (cut-off corners 28' were formed). The height of the stepped portion 3 was 2.48 mm. 500 of these aluminum cans were heated at 40℃ (can internal pressure approx. 4 kg/cm ² ) and 55℃ (can internal pressure approx. 6 kg/cm 2 ).
cm ² ) for two weeks, visual inspection was made for leakage from the double seam. The results are shown in Table 1.

[Table] (Effect of the invention) The present invention makes the part corresponding to the double seaming part of the edge part of the aluminum blank, which is to become the side seam part, thinner than other parts of the blank by coining process. By adding this process, which is relatively simple, has high productivity, and has relatively low power consumption, micro-leakage due to gaps in the double seam part corresponding to the side seam part is less likely to occur. This has the advantage that it is possible to produce a wrap-seam aluminum can body.

[Brief explanation of the drawing]

Figure 1 shows 2 parts corresponding to the side seam of a conventional can body.
FIG. 2 is a perspective view of an example of an aluminum can manufactured by the method of the present invention, and FIG. 3 is a cross-sectional view of the vicinity of the heavy seam portion, and FIG. 3 is a cross-sectional view of the side joint of the can of FIG. 2
A cross-sectional view of the part corresponding to the double seaming part before double seaming, FIG. 4 is a vertical cross-sectional view along the line - in FIG. 2,
Figure 5 is a cross-sectional view taken along the - line of Figure 2;
The figure is a plan view of an example of a blank for forming the body of an aluminum can shown in Fig. 2, and Fig. 7 is a plan view of an example of a blank for forming the body of an aluminum can in Fig. 6.
It is a longitudinal cross-sectional view along a line. 10... Aluminum can body, 11... Body, 1
2...Lid part (end plate), 13...Bottom part (end plate), 14
...Side seam part, 15...Double seam part, 16a,
16b...Organic adhesive layer, 18...Inner edge portion,
19... Outer edge portion, 18'', 19''... Portion corresponding to the double seaming portion of the edge portion, 27'... Aluminum blank.

Claims (1)

[Claims] 1. A method for manufacturing an aluminum can body, in which an end plate is double-sealed to a body part in which opposing edges of aluminum blanks are overlapped and joined via an organic adhesive to form a side seam part, A method for producing an aluminum can body, characterized in that a portion of the edge of the aluminum blank corresponding to the double seam portion is made thinner than other portions of the aluminum blank by coining processing.