JPH06179443A - Can lid - Google Patents

Abstract

PURPOSE:To provide a can lid which can prevent the content from guishin out much even when the inner pressure in the can rises up abnormally. CONSTITUTION:When the inner pressure of a can rises up abnormally, at first, a breakage is brought about at the thin part 61a in main scored. lines 61 and the gas and the liquid of the inside are leaked out from the breakage. Since this part 61a is covered with a tab 10, the leaked gas and liquid is prevented from guishing outward. When a breakage occurs and the contents leak out once, the inner pressure decreases as much as the quantity. Accordingly, other parts except the main scored lines 61 can be prevented from breaking. In this way, the content can be prevented from leaking much.

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 As such a can lid, for example, the one shown in FIG. 3 is widely known. The can lid 2 has a cut line 6 extending from the center of a can lid panel portion 4 formed in a substantially disc shape toward the outer periphery, and the score line 8 is formed by the cut line 6. The cutting line 6 is a main cutting line 61 that is a portion that is actually broken, and the main cutting line 61 is obtained by deforming the score portion 8.
And a sub-cut line 62 for assisting breakage of the. At the center of the can lid panel portion 2, a steion-type tab 10 for opening the score portion 8 is attached by a rivet 12. One end 10a of this tab 10
Is superimposed on the score line 6 and the score portion 8,
By pulling up the other end 10b, the main cut line 61 can be broken and the can lid 2 can be opened. The outer periphery of the can lid panel portion 4 has a substantially U shape in a sectional view.
A counter sink portion 14 (see FIG. 4) formed by being bent so as to form a letter shape is provided.

This can lid 2 is placed with the counter sink portion 14 inserted inside the opening of a bottomed cylindrical can body K whose one end face is open. Winding is applied to the outer periphery to seal the inside of the can. Such a technique is already well known as disclosed in Japanese Patent Publication No. 3-16207.

By the way, in such a conventional can lid, when the internal pressure of the can rises abnormally, a so-called buckling phenomenon may occur in which the counter sink portion 14 projects upward and is inverted. In particular,
When a carbonated drink is filled as the content and the can is heated to about 70 ° C. after sealing, such buckling may occur depending on the conditions. If this buckling occurs, a large stress acts on the cut line 6 and there is a risk of breaking this part. In the case of breakage, since the internal pressure of the can is relatively high, the content (mainly liquid content) blows out to the outside, which causes a problem that the surroundings are widely polluted.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and can prevent a large amount of contents from being blown out even when the internal pressure of a can rises abnormally. The purpose is to provide a can lid.

[0006]

[Means for Solving the Problems]
The remaining thickness of the score line in the portion covered by the tab is partially thin.

[0007]

According to the can lid of claim 1, when the internal pressure of the can rises abnormally, before or after buckling occurs,
First, a fracture occurs in the portion where the residual thickness is reduced, and the gas and liquid inside leak from the fractured portion.
But this part is covered by the tab, so
It is possible to prevent the leaked gas or liquid from blowing out to the outside. Further, once the contents are leaked due to the breakage as described above, the internal pressure is reduced accordingly, so that the breakage in other parts can be prevented. Therefore, the score portion does not open widely. Therefore, even if such breakage occurs, the leaking portion is relatively minute, and the leak amount of the content per time can be suppressed to a small amount.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A can lid according to an embodiment of the present invention will be described with reference to FIGS. In the description of the can lid of this example, the same components as those of the conventional can lid are designated by the same reference numerals and the detailed description thereof will be omitted.

In the can lid of this example, the remaining thickness of the main cutting line 61 (referred to as the plate thickness of the cutting line portion) in the portion 61a covered by the tab 10 is partially thin. The point is different from the conventional technology.

In the present embodiment, the portion of the portion 61a where the remaining thickness is thin (hereinafter, this portion is simply referred to as a thin portion) is located at the center of the rivet 12 and the score portion 8.
It is located on the line connecting the center of. The length of the thin portion along the extension direction of the main cutting line 61 is about 1 to 2 mm in this example. The thin portion is arranged at a position where the whole is covered with the tab 10. The remaining thickness t (see FIG. 2) of the thin portion is 0.090 to 0.13.
It is set to 0 mm. This thickness is set so that it will not be broken by vibration or impact that is usually applied during the transportation of the can.

The remaining thickness of the main cut line 61 other than the thin portion is set as follows. That is, in the main cutting line (the main cutting line in this portion is usually referred to as “pop part”) 61 near the center of the can lid panel portion 4 (that is, the center of the rivet 12), There is a main cutting line (a main cutting line in this part is usually referred to as a "tear part") 61 in a portion that is closer to the outer circumference of the can lid panel portion 4 than the pop portion by about 0.120 mm. Is set to about 0.100 mm. The minimum thickness of the sub-cut line 62 is 0.1.
It is about 8 mm. The plate thickness of the can lid panel portion 4 in a portion other than the cut line 6 (for example, point P ... See FIG. 1) is about 0.310 to 0.240 mm. These values are similar to those of a conventional can lid.

The can lid 2 of this example can be used for sealing a can in the same manner as a conventional can lid. Here, in the conventional can lid, there is an inconvenience that the contents blow out to the outside when the cut line 6 breaks due to an abnormal increase in the internal pressure of the can. However, in the can lid 2 of this example, when the internal pressure rises abnormally, the thin-walled portion of the portion 61a of the main cut line 61 first breaks, and the content leaks to the outside from this portion. The leaked contents come into contact with the lower surface of the tab 10 located thereabove, so that upward blowing is prevented.

In the can lid 2 of the present example, the remaining thickness of the so-called tear portion of the score line 61 is made substantially equal to the remaining thickness of the thin portion, but the tear portion breaks first due to an increase in internal pressure. There is practically nothing to do. This has already been confirmed experimentally. The reason is presumed to be as follows. That is, when the internal pressure of the can increases and the can lid 2 deforms so as to bulge upward, the amount of deformation in the vicinity of the center of the can lid 2 is larger than that of the outer peripheral portion thereof, and the applied stress is also larger. For this reason, in the can lid 2 of this example, the main cut line 61 can be broken first in the thin portion formed near the center thereof.

Therefore, according to the can lid 2 of this embodiment, although the contents leak a little, the tab 10 can prevent the contents from being blown upward. Therefore, there is an advantage that the range of being contaminated by the contents can be significantly narrowed.

Further, once the content leaks from the thin portion, the internal pressure of the can drops by that amount, so that the cut lines 6 of other portions are further broken unless there is an abnormal condition. There is nothing to do. Therefore, according to the can lid 2 of this example, it is possible to prevent the score line 8 of other portions from being broken and the score portion 8 to be widely opened. Therefore, it is possible to prevent the contents from leaking from the score portion 8 having a wide opening,
From this point as well, it is possible to narrow the range of contamination.

Furthermore, in the conventional can lid, if the internal pressure of the can rises abnormally, there is a risk that the tear portion formed with a small residual thickness will first break. In this case, almost all of the score portion 8 is turned up and a large amount of contents may leak. However, in the can lid 2 of this example, as described above, the thin portion formed in the pop portion of the main cut line 61 first breaks.
In this case, the phenomenon that the score portion 8 is turned up in a wide range does not occur. This is because the remaining thickness of the entire pop section,
In general, it is presumed that this is due to the fact that it is larger than the remaining thickness in the other part of the main score line 61.

Therefore, according to the can lid 2 of the present embodiment, also from this point, the amount of leakage of the contents can be reduced and the stain range can be narrowed as compared with the conventional can lid. There is.

In the can lid 2 of the above-mentioned embodiment, the thin portion of the main cutting line 61 at the portion 61a is located on the line connecting the center of the rivet 12 and the center of the score portion 8. It is not limited to this position. In short,
At the position covered by the tab 10, the score line 6
It is possible to exert the above-mentioned advantages by partially reducing the remaining thickness of the.

[0019]

According to the can lid of the first aspect of the present invention, since the remaining thickness of the score line in the portion covered by the tab is partially thin, the internal pressure of the can rises abnormally. In some cases, some of the score lines in the portion covered by the tab will break first. The contents leaked from the broken portion hit the lower surface of the tab and are prevented from being blown out, so that it is possible to prevent the inconvenience that the contents are widely polluted outside. Further, once the cutting line is broken, the internal pressure is reduced, so that the cutting line is not broken any more. Therefore, the score portion is not widely opened, and the leak amount of the contents can be suppressed low.

[Brief description of 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 of a main part of a can lid according to an embodiment of the present invention, which is a view corresponding to an enlarged view of portion B in FIG.

FIG. 3 is a plan view showing a conventional can lid.

FIG. 4 is an enlarged schematic view of an essential part taken along the line AA of FIG.

[Explanation of symbols]

 2 can lid 4 can lid panel part 6 cut line 8 score part 10 tab 61a part of the cut line covered by the tab

Claims (1)

[Claims] 1. A can lid panel portion having a score portion formed by a score line, and a tab attached to the can lid panel portion for opening the score portion. In the can lid arranged at a position covering at least a part of the score line, the residual thickness of the score line in the portion covered by the tab is partially thinned.