JPH11334734A - Can lid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a can lid wherein deformation of the can lid can be suppressed even if buckling occurs and score breakage is difficult to occur without increasing thickness of a base plate of the can lid. SOLUTION: A main score 5 is formed to surround an opening piece 8 on a panel deboss 11 formed with a recessed cross section, and an auxiliary score 6 is formed to be along the main score 5 on the opening piece 8. A thinned easy-to-deform portion 10 is formed on a part on a rolled portion 7 where a can lid 12 has been rolled with a can body 9. Since the easy-to-deform portion 10 is provided on the rolled portion 7, deformation of a top plate 1 itself can be suppressed even if an internal pressure in a container rises, thereby reducing influence to the main score 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a can lid used for sealing a can, and more particularly to a can lid suitable for a beverage can.

[0002]

2. Description of the Related Art Conventionally, in a can lid, a so-called buckling, in which a beverage container containing a gas-containing beverage such as carbonated beverage, a part of the can lid swells from the inside when the internal pressure increases during storage, is called a buckling. A phenomenon may occur. The location of the bulge caused by buckling is indiscriminate, and if buckling occurs near the score, the risk of score breakage increases. For this reason, a method of providing an easily deformable portion where buckling is positively generated at a position away from the score is adopted.

[0003] As a can lid of this type, the one disclosed in Japanese Patent Application Laid-Open No. 5-69066 shown in FIG. 5 is known. In this can lid, a thin-walled reinforcing portion 58 is arranged by coining the peripheral groove 52 of the top plate portion 51 except for the distal end portion of the opening piece 56 surrounded by the score 55, and The pressure-resistant weakening portion 57 composed of an embossed recess near the periphery of the plate portion 51
Are provided, and the pressure-resistant weakening portion 57 is an easily deformable portion where buckling is generated from this position.

[0004] Alternatively, in a can lid disclosed in Japanese Patent Application Laid-Open No. 5-65162, as shown in FIG.
Is divided into an upper part and a lower part in FIG. 6 by an axis x orthogonal to the axis y connecting the center of the top plate 61 and the tip of the opening piece 66, and passing through the center of the top plate 61. An easy-to-deform portion comprising a cut 67 is provided at the peripheral edge of the top plate 61 on the upper side in FIG. 6, which does not include the buckling.

In Japanese Patent Laid-Open No. 5-112357, as shown in FIG. 7, the top plate 71 is connected to an axis y connecting the center of the top plate 71 and the tip of the opening piece 76 with respect to an axis y. It is divided into four parts in a fan shape by an axis x orthogonal to the center of the top plate part 71, and a seat is located near the peripheral edge 72 of one or both of the two fan shapes on the side not including the opening piece 76. The buckling portion 77 is provided, and a buckling portion 77 having a small buckling property is provided also on a portion including the opening piece 76. The buckling portion 77 is an easily deformable portion.

[0006]

However, when the easily deformable portion is provided on the top plate portion as described above, the deformation of the can lid causes the deformation on the top plate portion from the stage where the internal pressure of the container is low. Since it concentrates on the easy part, the internal pressure strength may be reduced as a whole. Further, when the plate thickness of the can lid is small, when the internal pressure of the container rises, the deformation of the entire can lid increases, and the effect of the easily deformable portion decreases. On the other hand, when the can lid is thickened, the deformation of the can lid is reduced and the possibility of score breakage is reduced, but this leads to an increase in manufacturing cost.

[0007] The present invention has been made in view of the above-mentioned circumstances, and it is possible to suppress the deformation of the can lid even if buckling occurs without increasing the thickness of the base plate of the can lid, and to make it difficult for score breakage to occur. It is intended to provide a lid.

[0008]

In order to solve the above-mentioned problems, the present invention provides a top plate having an opening piece surrounded by a main score, and a tightening portion provided on a periphery of the top plate. A tab fixed in the vicinity of the opening piece of the top plate portion, and by raising one end of the tab, pressing the opening piece downward while bringing the other end of the tab into contact with the upper surface of the opening piece. In the can lid having a configuration in which the main score is cut and the opening piece is pressed down to the inner surface side of the top plate to open, a thinned easily deformable portion is formed in a part of the winding portion. Features.

According to the present invention, when buckling occurs, the easily deformable portion of the tightened portion is preferentially deformed.
Therefore, the deformation of the top plate itself can be suppressed, and the influence on the score can be reduced. In this case, the thickness of the easily deformable portion is set to be 20% or more and 80% or less of the original plate, and the position where the easily deformable portion is formed is set to a position avoiding the vicinity of the main score, and By forming it in a range of 10 degrees or more and 180 degrees or less, a desired effect can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a can lid according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a can lid of the present invention, and FIGS. 2 and 3 are an AA enlarged sectional view and a BB enlarged sectional view of a peripheral portion of a top plate 1 of FIG. 1, respectively.
The can lid 12 has a top plate 1, a peripheral groove 2 provided on the periphery of the top plate 1, and a tightening portion 7 that is wound around the can body 9. A panel deboss 11 having a concave cross section is formed in the vertical direction of the middle plane. Then, the tab 3 is inserted into the panel deboss 11.
Is provided. The tab 3 is connected to a center portion of the top plate 1 by a rivet 4. By pulling up one end of the tab 3, the other end of the tab 3 is brought into contact with the upper surface of the opening piece 8 to form the opening 3. The main score 5 is cut by pressing the piece 8 downward, and the opening piece 8 is
The body is pushed down and opened inside the inner surface of the main body.

The main score 5 is formed on the panel deboss 11 so as to surround the opening piece 8. On the opening piece 8, the auxiliary score 6 is parallel to the main score 5 along the inside of the main score 5. It is formed in a double shape.

An easily deformable portion 10 which is thinner than the thickness ta of the original plate of the wrapped portion 7 is formed in a part of the wrapped portion 7 which is wrapped around the can body 9. The plate thickness tb of the portion 10 is formed to be not less than 20% and not more than 80% of the plate thickness ta of the original plate.

Further, as shown in FIG.
A line connecting the front end of the opening piece 8 and the center O of the top plate 1 is defined as a line L, and the buckling position angle is determined from the point where the line L and the tightening portion 7 are located on the opposite side to the vicinity of the front end of the opening piece 8. When the portion at the position of ψ is the buckling position M where the buckling is desired to occur, the thinning range angle θ with respect to the center O of the top plate 1 based on the buckling position M
Is formed on the tightened portion 7 in the range of.

In such a can lid, when buckling occurs due to an increase in the internal pressure of the can container, the tightened portion 7 of the can lid 12 is deformed outward with respect to the center O of the top plate 1. However, the thickness of the tightened portion 7 in the range where the buckling position M where the buckling is to be generated is present is reduced,
By forming the portion as the easily deformable portion 10, the easily deformable portion 10 is easily deformed, and when the internal pressure of the can container increases, buckling occurs preferentially from the easily deformable portion 10. It is possible to suppress deformation of the plate portion 1 and prevent score breakage.

In this case, if the plate thickness tb of the easily deformable portion 10 is too thin, the force for winding the can lid 12 and the can body 9 is weakened, and the easily deformable portion 10 itself is easily deformed. The internal pressure strength decreases. On the other hand, the sheet thickness tb
If the thickness is too large, the easily deformable portion 10 is not sufficiently deformed, and the desired effect cannot be obtained.

On the other hand, if the thinning range angle θ, which is the range in which the easily deformable portion 10 is formed, is too small, the action of the crimping portion 7 to be deformed outward is hindered, and buckling is preferentially performed at a desired position. This eliminates the effect of trying to make it happen. On the other hand, if the thinning range angle θ is too large, the easily deformable portion on the tightening portion 7 is formed in a wide range, and therefore, at a plurality of points within the range of the thinning range angle θ on the tightening portion 7. Buckling may occur, or buckling may occur at a position shifted from the buckling position M.

Therefore, the plate thickness tb of the easily deformable portion 10 is set to a thickness of 20% or more and 80% or less of the plate thickness ta of the original plate. With reference to a line connecting the center O of the plate portion 1 and the buckling position M on the tightening portion 7 to be buckled, the top plate portion 1
A desired effect can be obtained by setting the center O to 10 degrees or more and 180 degrees or less.

<Experimental Example> An experimental example of a test for determining the thinning range angle θ using the can lid of the present invention will be described. The test was performed under the conditions shown in Table 1 for the buckling position angle ψ and the thinning range angle θ. In the test method, a plurality of samples were prepared, the position where buckling occurred was counted for each sample, and the number was set as the number of buckling. Normally, buckling occurs up to four times per sample, but the buckling position generated at the first time was counted as the number of bucklings for each sample. Also,
While buckling occurred, the number of blow-ups leading to breakage of main score 5 was defined as the blow-up number. As a comparative example, a can lid in which the easily deformable portion 10 was not provided on the tightening portion 7 was used.

[0019]

[Table 1]

Table 1 shows the test results. In Table 1, the numerical value in the upper row indicates the number of bucklings, and the numerical value in the lower row indicates the number of blow-ups. The buckling occurrence position angle ψ ′ indicates the position angle when buckling actually occurs. Easy deformation part 10
In the comparative example in which is not provided, it can be confirmed that buckling occurs at various positions. As shown in Experimental Examples 2 to 7, 9 and 10, the thinning range angle θ is 10 °
When the angle is set to 180 °, it can be confirmed that buckling occurs near the desired buckling position angle ψ, the buckling position M is controlled, and blow-up does not occur. However, as shown in Experimental Example 1, if the thinning range angle θ is as small as 5 °, the effect of the thinning is not exhibited, and buckling occurs at a position other than the desired buckling position angle 、, and What led to blow-up was confirmed. Further, as shown in Experimental Example 8, when the thinning range angle θ is set to 180 ° or more,
Because the part where the winding part 7 is deformed is wide,
It can be confirmed that buckling occurs at a plurality of points shifted from the buckling position M. Also, as shown in Experimental Example 11, even if the thinning range angle θ is set to 30 °, if the easily deformable portion 10 is provided near the main score 5, blow-up occurs due to buckling. It is confirmed that. Therefore, the easily deformable portion 10 has a thinning range angle θ of 10 ° at a position avoiding the vicinity of the main score 5.
The angle is set to be in the range of 180 °.

[0021]

According to the present invention, since the easily deformable portion is provided on the tightening portion where the can lid and the can body are connected, even if the internal pressure of the container increases, the deformation of the top plate itself can be prevented. Can be suppressed, and the influence on the main score can be reduced. In this case, the thickness of the easily deformable portion is set to 20% or more of the original plate.
The thickness is set to 0% or less, and the position where the easily deformable portion is formed is a position avoiding the vicinity of the main score, and is formed in a range of 10 degrees or more and 180 degrees or less with respect to the center of the top plate portion. A desired effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of a can lid according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view taken along the line AA of FIG.

FIG. 3 is an enlarged sectional view taken along the line BB in the vicinity of an easily deformable portion in FIG. 1;

FIG. 4 is a diagram illustrating a forming range of an easily deformable portion.

FIG. 5 is a plan view showing a conventional can lid.

FIG. 6 is a plan view showing a conventional can lid.

FIG. 7 is a plan view showing a conventional can lid.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Top plate 2 Peripheral groove 3 Tab 4 Rivet 5 Main score 6 Auxiliary score 7 Winding part 8 Opening piece 9 Can body 10 Deformable part 11 Panel deboss M Backing position O Top plate center θ Thinning range angle ψ Back ring position angle ψ 'Buckling occurrence position angle ta Original plate thickness tb Deformable part thickness

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenichi Shibata 1500 Suganuma, Koyama-cho, Sunto-gun, Shizuoka Prefecture Inside the Aluminum Can Development Center Mitsubishi Materials Corporation

Claims (2)

[Claims] 1. A top plate having an opening piece surrounded by a main score, a tightening portion provided on a periphery of the top plate, and a tab fixed near an opening piece of the top plate. By raising one end of the tab, while pressing the other end of the tab on the upper surface of the opening piece, the opening piece is pressed downward to cut the main score, and the opening piece is placed on the inner surface of the top plate portion. A can lid configured to be pushed down to the side to open, wherein a thinned easily deformable portion is formed in a part of the winding portion. 2. The thickness of the easily deformable portion is 20% of the original plate.
The thickness is not less than 80% and not more than 80%, and the thinned area is formed at a position avoiding the vicinity of the main score and in a range of not less than 10 degrees and not more than 180 degrees with respect to the center of the top plate portion. The can lid according to claim 1, wherein