JP2000016424A - Can cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a can cover preventing rupture caused by score cracks when a can cover with a wide opening is loaded with an internal pressure. SOLUTION: An arc-shaped can cover is provided with a stay-on tab, and an axial line connecting the center 5 with an opening end 10 of a can cover forms a short axis in the shape of a breaking opening section 3, and a step section 9 corresponding to the end 10 of the breaking opening section 3 is cut partially, and wall sections 13a and 13b extending in the radius direction of the can over are formed on the cut section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easy-open can lid, such as a beverage can, which is opened by a stab-type tab.

[0002]

2. Description of the Related Art In recent years, the opening portion of a can lid of a partially open can (a type of can opening a part of a can lid) such as a beverage can has various adverse effects due to disposal of a tub after opening. For this reason, a stay-on type tab in which the tab and the can lid are partially connected even after the can is opened is widely used.

FIG. 4 shows an example of a can lid provided with such a stay-ion type tab. FIG. 4 is a plan view of a can lid of a conventional beverage can (for a 350 ml can, having an outer diameter of 64 mm). In FIG.
The substantially disk-shaped can lid main body 1 has a groove-shaped countersink 4 on the peripheral edge. Further, the can lid body 1 has a break opening 3 defined by a substantially arc-shaped score (cut) 2 engraved on the surface, and a stained tab 8 overlapping the opening 3. The stay-on tab 8 has a push-down portion 6 at one end and a pull-up portion 7 at the other end, and is fixed to the can lid body 1 at the center 5 of the can lid by rivets or the like, and extends in the radial direction of the can lid. Are there. A substantially arc-shaped stepped portion (an uneven portion) 9 for reinforcing the can lid is provided in the can lid main body between the score 2 and the counter sink 4.

In the can lid having such a structure, the opening 3
For the opening of
By pressing down, the depressed portion 6 presses the breaking opening 3 downward, and cuts the substantially arc-shaped score 2 engraved on the surface from the opening start end to the end, and further,
The breaking opening 3 is pushed down to the inside of the can to open the beverage opening.

[0005] In a beverage can using such a can lid provided with a stay-on type tab, particularly when the content is filled with carbonated beverage or beer, the internal pressure of the can is increased due to vibration, impact or temperature rise. Is easy to rise. And
When the increased internal pressure exceeds the pressure resistance of the can lid, a part of the vicinity of the countersink 4 is plastically deformed and instantaneously protrudes upward in a horn-like manner. Here, when the vicinity of the counter sink 4 close to the score 2 is cornered, the score 2 may be broken from a portion close to the counter sink 4 and the contents of the can may blow out.

For this reason, conventionally, utility model registration No. 2539
In No. 914, etc., the portion of score 2 that is close to countersink 4 (near the bottom of U-shaped score 2) has an upward convex, which makes the score 2 deeper than the cut depth of score 2 in other portions. A shallowly formed step is provided. In this prior art, by providing the step, the stress applied to the score 2 in the can lid portion adjacent to the countersink 4 is received to prevent the breakage of the score 2 due to an increase in the internal pressure of the can. It is assumed that.

[0007]

However, as shown in FIG. 4, the shape of the opening 3 of the can lid, which is the object of the Utility Model Registration No. 2539914, is that the center 5 of the lid and the tip 10 of the opening 3 are formed as shown in FIG.
(A portion surrounded by a dotted line, hereinafter referred to as an opening front end portion 10) is an ellipse having a long axis. Therefore,
In the vicinity of the opening front end portion 10, the length of the portion S where the score 2 is in the circumferential direction of the can lid is short and its arc radius is small. As a result, the overall shape of the opening 3 is a tapered narrow opening.

Then, according to the shape of the opening, the score 2
The radius of the arc of the tapered surface (can lid surface) 11 in the direction of the tip of the opening 3 that connects the stepped portion 9 provided around the periphery and the counter sink 4 is also reduced. For this reason, the tapered surface (can lid surface) 12 surrounding the periphery of the opening 3 increases the cross-sectional coefficient with respect to the bending stress applied in the axial direction connecting the center 5 of the can lid and the tip end 10 of the opening, and projects in this direction. Has the effect of suppressing.

However, in recent years, can lids having a wider opening have been manufactured for can lids having such a tapered narrow opening from the viewpoint of ease of drinking. In the example of the can lid having such a wider opening, as shown in FIG. 3, the shape of the opening 3 and the step 9 around the opening connects the center 5 of the can lid and the opening 3. It has an elliptical arc shape whose axis is the short axis. Therefore, this results in:
The overall shape of the opening 3 is an opening with a wide taper.

[0010] With the wide opening shape, in the vicinity of the opening front end portion 10 (portion surrounded by the dotted line), the arc of score 2 is the same direction as the circumferential direction of the can lid. , The portion S where the distance between the opening 3 and the counter sink 4 is the narrowest, and the tapered surface 12 at the tip of the opening 3
Is longer than that of the can lid having the narrow opening. Therefore, the score
The radius of the arc of the tapered surface 11 that connects the step portion 9 provided around 2 and the counter sink 4 also increases. Therefore, the tapered surface 12 surrounding the periphery of the opening 3 reduces the cross-sectional coefficient with respect to the bending stress applied in the axial direction connecting the center 5 of the can lid and the opening end portion 10, and the effect of suppressing the overhang in this direction decreases. I do. As a result, when internal pressure is applied to the can lid, bending deformation (deformation or stress due to a force to expand in the curved surface direction of the can lid, hereinafter referred to as bending deformation or bending stress) occurs at the opening end portion 10. It is easy to burst due to cracking with a low strength score of 2.

Therefore, the utility model registration No. 2539914
By simply providing a step portion formed shallower than the depth of score 2 in the portion close to the counter sink 4 of score 2, such as the number, in a can lid having a wide opening,
Bending deformation at the opening tip 10 cannot be prevented, and rupture due to a crack having a low strength of score 2 cannot be prevented.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a can lid having a wide opening at the tip of the breaking opening 3 when an internal pressure is applied. It is an object of the present invention to provide a can lid capable of suppressing bending deformation of the can and preventing rupture due to a crack at score 2.

[0013]

In order to achieve this object, the gist of the can lid of the present invention is to provide a substantially disc-shaped can lid body 1 having a groove-shaped countersink 4 on the peripheral edge thereof, and a can lid body 1 A breaking opening 3 defined by a substantially arc-shaped score 2 engraved on the surface, and a depressing portion overlapping the breaking opening 3
6 at one end, a pull-up portion 7 at the other end, and a stationary tab 8 fixed to the can lid body and extending in the radial direction of the can lid. In the lid body, a convex stepped portion 9 for reinforcing the can lid is a can lid provided in an arc shape, and the shape of the breaking opening 3 is such that the center of the can lid 5 and the tip of the breaking opening 3 are formed. An ellipsoidal arc shape in which the axis connecting to 10 is a short axis, the stepped portion 9 corresponding to the distal end portion 10 of the break opening 3 is partially notched, and the diameter of the can lid is formed in the notched portion. Wall extending in the direction
13a and 13b.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a can lid according to the present invention will be described below with reference to FIGS. The basic configuration of the can lid according to the present invention is the same as the configuration of the conventional can lid having a wide opening as shown in FIG. That is, a substantially disc-shaped can lid main body 1 having a groove-shaped countersink 4 on the periphery, and a substantially arc-shaped score engraved on the surface of the can lid main body 1
2 and a push-down portion 6 overlapping the opening 3 at one end, and a pull-up portion 7 at the other end.
And a stainless steel tab 8 fixed to the can lid body by rivets 5 and extending in the radial direction of the can lid, and a can lid reinforcement between the score 2 and the counter sink 4 is provided. Step 9 is provided.

The shape of the convex step 9 has various variations depending on the design or design of the can lid.
In addition to the simple substantially arcuate shape shown in FIG. 1, there are also appropriately shaped ones such as a complicated substantially arcuate shape shown in FIG. 3, and are appropriately selected in the present invention. However, the opening of the can lid in the present invention is not a can lid having a narrow opening as shown in FIG. 4 but a wide opening as shown in FIG. That is, as shown in FIG. 1, the shape of the opening 3 is such that the axis connecting the center 5 of the can lid and the opening tip 10 is the short axis.
It has an elliptical arc shape.

In a can lid having a stay-on type tab having such a wide opening, X- in FIG.
As shown in FIG. 2 (a), which is an X-ray cross section, a portion corresponding to the opening end portion 10 of the step portion 9 (a portion where the arc of score 2 in FIG. 1 is in the same direction as the circumferential direction of the can lid). The portion where the distance between the opening 3 and the counter sink 4 is the narrowest) is cut out, and the wall 13a extending in the radial direction of the can lid,
13b is formed on the surface of the can lid body. That is, in FIG.
Compared to the conventional can lid having a steon-type tab having a wide opening in FIG. 2B, which is a cross section taken along the line Y-Y, it corresponds to the opening end 10 of the step 9 for reinforcing the can lid. The portion is notched, and the step portion 9 has a shape in which only the portion corresponding to the opening end 10 is interrupted. As a result, wall portions 13a and 13b extending in the radial direction of the can lid are formed at a portion (end portion) of the step portion 9 corresponding to a tip portion 10 (a dotted line portion in FIG. 1) of the break opening portion 3. Have been.

As shown in FIG. 2 (b), the walls 13a and 13b are arranged such that when the can lid having an arc shape receives the internal pressure of the can, the direction of the curved surface of the can lid (A− in FIG. 2 (b)). It acts as a reinforcing plate or rib against bending deformation or bending stress due to a force that expands in the (A direction). Therefore, when the deformation is applied, breakage due to expansion of score 2, which is the weakest part of the can lid, is prevented.

The distance between the walls 13a and 13b, ie, the step
If the width of the notched portion 9 is too large, when the can lid is opened, the opening 3 is pressed downward by the depressed portion 6 of the stay-on tab 8, and the substantially arc-shaped portion engraved on the surface is pressed. When the breaking opening 3 is pushed down to the inside of the can, the rigidity of the can lid around the opening is insufficient and the can 2 around the opening is cut. The lid is also pushed down, making opening difficult.

On the other hand, the interval between the walls 13a and 13b may be small, but if it is too small, it becomes difficult to form the can lid. Therefore, without insufficient rigidity of the can lid around the opening,
In response to the internal pressure of the can, the wall portions 13a and 13b have a reinforcing force against deformation or stress due to a force that expands in the curved surface direction of the can lid (A-A direction in FIG. 2 (b)). Try to determine the interval.

The widths and heights of the walls 13a and 13b depend on the required width and height of the original step portion 9 on which the walls are provided. The required width or height of the step 9 is determined by the degree to which the rigidity of the can lid portion around the opening is maintained. Deformation or stress caused by the force that expands in the direction of the curved surface of the can lid (A-A direction in Fig. 2 (b)) (the bending stress or the bending stress applied in the axial direction connecting the center 5 of the can lid and the opening tip 10). Bending stress) is determined by the required increase in section modulus. Therefore,
As will be described later, when the internal pressure applied to the can lid is applied, the bending stress applied to the score 2 portion is obtained by simulation using the FEM (finite element method), and the amount of reduction in bending stress or the allowable amount of bending stress is determined. Then, the width and height of the step portion 9 and the distance between the wall portions 13a and 13b are determined.

At this time, the allowable amount of bending stress and the width and height of the step portion 9 cannot be shown as a quantitatively preferable range because the design and the design method of the can lid are various in practice. . However, for example, as described in Examples below, the bending stress applied to the score portion of a conventional can lid having a narrow opening, which is less likely to break than a can lid having a wide opening, Based on a relative comparison with the above, the fact that the bending stress can be reduced to a value close to or less than the bending stress is a criterion for selecting the allowable amount of bending stress and the size of the width and height of the step portion 9. be able to.

As described above, the opening end 10 of the step 9
By forming the wall portions 13a and 13b in portions corresponding to the above, the bending stress itself applied to the curved surface direction of the can lid can be suppressed, and the bending deformation at the tip of the opening portion 3 when an internal pressure is applied is suppressed. In particular, it is possible to prevent cracking at a score of 2 having low strength, thereby preventing rupture of the can lid.

[0023]

Next, embodiments of the present invention will be described. The figure above
Conventional can lid type A with narrow opening shown in 4
The internal pressure of the conventional can lid type B having the wide opening shown in FIG. 3 and the can lid type C of the present invention having the wide opening shown in FIG.
The bending stress applied to the score portion near the opening tip 10 when a load of cm ² was applied was analyzed by FEM simulation. Table 1 shows the results.

As is clear from Table 1, the bending stress applied to the score portion close to the opening tip 10 is the conventional can lid type A having a narrow opening, and the present invention having a wide opening. The size of the can lid type C becomes larger in the order of the conventional can lid type B having a wide opening. The bending stress of the conventional can lid type A having a narrow opening is 0.1977.
Conventional can lid type with a wide opening for GPa
The bending stress of B is 0.4 GPa, and the bending stress applied to the score part due to the widening of the opening is more than twice as large.The possibility of breaking the can lid due to the widening of the opening increases. Is supported.

The bending stress of the can lid type C of the present invention having a wide opening is 0.229 GPa, which is larger than that of the conventional can lid type B having a wide opening. It can be seen that the bending stress is remarkably reduced, and it is harder to break than the can lid having a wide opening, and the bending stress is comparable to that of the conventional can lid type A having a narrow opening. Therefore, according to the gist of the present invention, the tip of the break opening 3
Steps 9 corresponding to 10 are partially cut out, and the cutouts have walls 13a, 13b extending in the radial direction of the can lid.
Forming the center 5 of the can lid and the opening tip 10
The bending stress itself acting in the axial direction that connects to the opening can be suppressed, and the bending deformation at the tip of the opening 3 when internal pressure is applied can be suppressed. It can be proved that the rupture of the can be prevented.

[0026]

[Table 1]

[0027]

According to the present invention, in a can lid having a wide opening, a can lid for suppressing bending deformation at the tip of the opening when internal pressure is applied and preventing the can lid from bursting. Can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view of a can lid having a wide opening, showing an embodiment of the present invention.

2 is a sectional view taken along line XX of FIG. 1 and a sectional view taken along line YY of FIG. 3;

FIG. 3 is a plan view of a can lid showing another embodiment of the present invention.

FIG. 4 is a plan view of a conventional can lid having a wide opening.

FIG. 5 is a plan view of a conventional can lid having a narrow opening.

[Explanation of symbols]

1: Can lid body, 2: Score, 3: Break opening, 4: Counter sink, 5: Center of can lid, 6: Depressed part, 7:
Lifting part, 8: Stained tab, 9: Step, 10:
Opening tip, 11: tapered surface, 12: tapered surface, 13: wall

Claims (1)

[Claims] A rupture opening defined by a substantially disk-shaped can lid body having a groove-shaped countersink at its periphery, and a substantially arc-shaped score formed in the surface of the can lid body.
3 and a push-down portion 6 superimposed on the breaking opening 3 at one end, a pull-up portion 7 at the other end, and a stationary tab fixed to the can lid body and extending in the radial direction of the can lid.
A can lid body provided with a convex stepped portion 9 for reinforcing the can lid on the can lid body around the breaking opening 3 in an arc shape, the shape of the breaking opening 3 Has an elliptical arc shape in which the axis connecting the center 5 of the can lid and the tip 10 of the break opening 3 is a short axis, and a step 9 corresponding to the tip 10 of the break opening 3 is partially formed. A can lid characterized in that walls 13a, 13b extending in the radial direction of the can lid are formed in the notch portion while being cut out.