JP2853590B2 - Can lid with stay tub - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a can lid with a stay tab, and more particularly, to a can lid with a stay tab having improved drop strength.

[0002]

2. Description of the Related Art Recently, a stainless steel tub is frequently used from the viewpoint of environmental protection. However, a score 20 of a conventional can lid with a stainless steel tub generally has a score near a rivet 21 as shown in FIG. And is formed in a double score that is folded back while leaving a bent portion 22 on the side of the rivet.
The stay-on tab does not reduce the remaining thickness of the score by about 100 to 80 μm compared to the conventional lid with a ring pull tab because of the opening mechanism of pushing the score panel surrounded by the score line into the can through the tab. And can not open.
Therefore, when the can lid with the stay-on tab is dropped in a state where it faces downward and a given impact is applied to the can lid, the score tends to be cracked more easily than in the case of the conventional can lid with the ring pull tab.

[0003]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in order to solve the above-mentioned disadvantages of a can lid with a stay-on tab, which has a smaller score thickness and a lower drop strength than a can lid with a ring pull tab. It is an object of the present invention to provide a can lid with a stay-on tub that can increase the drop strength and effectively prevent the occurrence of cracks in the score due to the drop even if the remaining score thickness is small.

[0004]

The inventor of the present invention has conducted various experiments to solve the above-mentioned problems. As a result, in a conventional can lid with a stay-on tub, a phenomenon in which a crack is generated when the can is dropped is described. It was found that stress was concentrated on the score near the rivet in the center of the lid due to the impact and water hammer action at the time of falling, the score of this part was bent, and this occurred in combination with the notch effect,
As a result of further research, the present inventors have found a means for avoiding stress concentration on the score portion when falling, and have reached the present invention.

[0005] That is, the can lid with a stay-on tub of the present invention which solves the above-mentioned problems has a main score near the rivet.
Opposite to the main score, a weakening line for easy bending that prevents stress concentration on the main score is formed on the surface of the can lid panel near the rivet opposite to the main score . The weakening line can be formed by score processing, coining processing, or the like.

[0006] The weakening line may be formed in a straight line, a curved line, or a combination thereof, and may be formed as a single line or a double line. The weakened line can be formed intermittently even if it is not necessarily continuous.

[0007]

[Function] In the vicinity of the rivet where the stress of the drop impact tends to be concentrated, another weakening line is provided on the rivet side opposite to the score to form an easily bent portion, so that the impact and water hammer at the time of falling By dispersing the stress due to the action, stress concentration on the main score can be prevented, and bending deformation and cracking of the main score can be effectively prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a can lid with a stay tab according to the present invention will be described in detail with reference to FIG. In the drawing, reference numeral 1 denotes a can lid with a stay tub according to the embodiment of the present invention, and a weakening line 5 for easy bending is formed on the rivet side can lid panel surface 4 with respect to the main score 3 near the rivet 2. Except for this point, it is formed in the same structure as a conventional can lid with a stay-on tab. In the present embodiment, the weakening line 5 is formed by scoring one straight line as shown in FIG. 4A, as clearly shown in FIG. 1B. In the figure, reference numeral 6 denotes a score panel, and reference numeral 7 denotes a tab.

In order to investigate the drop strength of the main score of the can lid with a stay tub having the above structure, the can lid with a stay tub of this embodiment was used for a 350 g negative pressure can, and the can lid was mounted. With the side facing down facing down, 30 cans were respectively dropped from a height of 40 cm to 80 cm, and the occurrence of cracks in the score was examined. As a comparative example, as shown in FIG.
A drop test was performed on the conventional can lid with a stay-on tub having only the score 20 under the same conditions, and the cross-sectional shape of the can lid panel after dropping and the occurrence of cracks in the score were examined.

As a result, in the present embodiment, the cross-sectional shape of the panel is normal even if it falls from 70 cm, as shown in FIG. However, in the conventional can lid 25 shown in the comparative example,
Upon dropping from the cm, as shown in FIG. 6, non-uniform deformation which was considered to be bent around the beginning of the score was observed. This is presumed to be due to the concentration of stress at the start of the score, which is a weak part. On the other hand,
The state of occurrence of score cracks in the can lid of the present example is the result shown in Table 1, and it can be said that the effect on score cracks is recognized, and stress concentration due to drop impact on the main score portion is effectively prevented. .

[Table 1] In the table: numerator / denominator = score of score cracking cans / falling cans

As is clear from the above experimental results, the can lid of the present embodiment showed no cracks in the score up to a drop height of 70 cm, and no one can was found by dropping from 80 cm. It was only found.

On the other hand, in the can lid of the comparative example, one can was found at a falling height of 50 cm, and two cans were found at a falling height of 60 cm. From this result, there is a clear difference in the drop strength between the present embodiment and the comparative example, and as shown in the present invention, the can cover panel surface 4 on the rivet side with respect to the main score 3 is easily bent. It has been confirmed that the formation of the weakening line 5 has a special effect on the drop strength.

In the above embodiment, the line of weakness for easy bending is formed as one straight line. However, the form of the line of weakness is not limited to the above embodiment, and various forms can be adopted. a) to (g)
Shows another embodiment of the weakening line for easily bending.

The weakening line 10 of the embodiment shown in (a) is a combination of two parallel straight lines, and the weakening line 11 of the embodiment shown in (b) is intermittently excluding the middle part near the rivet. The weakening line 12 of the embodiment shown in (c) is formed intermittently so as to sandwich a rivet, and the weakening line 13 of the embodiment shown in (d) is the same as that of the embodiment shown in (c). Corresponds to a continuous arc along the rivet outer periphery,
The weakening line 14 of the embodiment shown in (e) is formed in a shape that is curved in an arc shape, and the weakening line of the embodiment shown in (f) is a shape in which both straight ends are bent to the opposite side to the main score. Further, the weakening line 16 of the embodiment shown in (g) is formed in a shape in which two weakening lines 15 are formed in parallel.

Although the weakening line is formed by score processing with the score tool 18, it may be formed by coining with the coining tool 19 as shown in FIG. 17 ₁ and 17 ₂ indicate can lid panel surfaces, respectively.

[0016]

According to the present invention, the stress due to the impact and water hammer action at the time of falling is dispersed to prevent the concentration of stress on the main score, thereby effectively preventing bending deformation and cracking of the main score. be able to.

[Brief description of the drawings]

FIG. 1A is a plan view of a can lid with a stay-on tab according to an embodiment of the present invention in a state where a tab is not attached, and FIG. 1B is a plan view showing only a main part thereof. .

FIG. 2 is a cross-sectional view showing a state after the can lid with a stay-on tab according to an embodiment of the present invention has fallen;

FIGS. 3 (a) to 3 (g) show different embodiments with different weakening lines.

4A and 4B are explanatory diagrams showing a method of forming a weakening line, wherein FIG. 4A shows a score processing state, and FIG. 4B shows a coining processing state.

FIG. 5 is a plan view of a main part showing a form of a score of a conventional can lid with a stay tab.

FIG. 6 is a sectional view showing a state after a conventional can lid with a stay tab is dropped.

[Explanation of symbols]

1 Can lid with stay-on tab 2 Rivet 3 Main score 4 Can lid panel surface 5,10-16 Weak line

Claims (5)

(57) [Claims] Claims: 1. Opposing a main score near a rivet ,
Place the main score on the surface of the can lid panel near the rivet opposite to the main score .
A can lid with a stay-on tab, wherein a weakening line for easy bending is formed to prevent stress concentration on the score . 2. The can lid with a stay-on tab according to claim 1, wherein the weakening line is formed by score processing. 3. The can lid with a stay-on tab according to claim 1, wherein the weakening line is formed by coining. 4. The can lid with a stay tab according to claim 1, wherein the weakening line is a straight line. 5. The can lid with a stay-on tab according to claim 1, wherein the weakening line is a curve.