JP2005075382A - Can lid for beverage and beverage can - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a can lid with a thin thickness and a can for beverage equipped with the can lid which have a pressure resistance enough to surely prevent buckling from occurring within a regulated pressure, and do not generate a local sharp projection but perform scattering of a content when elevation of an inner pressure exceeding it occurs. <P>SOLUTION: A metal can lid for beverage having an annular counter sink inside of a chuck wall keeps ϕ2 is set at a diameter of 70-80% of ϕ1, θ1 is 30-60° and θ2 is 10-35° (but θ1>θ2), and R1 at 3-10 mm [wherein ϕ1 is a diameter (mm) of the can lid; ϕ2 is a diameter (mm) between counter sinks; θ1 is an angle between the chuck wall and a vertical line of the counter sink; θ2 is an angle between the chuck wall and an extending line of the outer wall of the counter sink; and R1 is a radius at a jointing position between the chuck wall and the outer wall of the counter sink]. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a metal can lid used for a metal can for beverages having a relatively high internal pressure, such as a beer can or a carbonated soft drink beverage can, and a metal can for beverage provided with the can lid. Even if buckling deformation occurs due to exposure to high temperatures, the can lid is not torn at the countersink part and score, and the thickness of the countersink is kept thin, keeping the score sink and opening operation difficult. The present invention relates to a beverage can lid that can be used.

The outer periphery of the can lid used for beverage cans with relatively high internal pressure, such as beer cans and carbonated soft drink cans, has a curl shape that smoothly wraps around the back of the can barrel flange when tightening, and the inner periphery has an internal pressure Therefore, a groove-shaped counter sink is provided as a shape that increases the pressure resistance and prevents the back link deformation. In this counter sink processing, it is known that the pressure resistance of the can lid can be improved by reducing the diameter of the counter sink. For example, it has been proposed that the diameter between the counter sinks is preferably less than 80% of the diameter of the can lid (see, for example, Patent Document 1).
The opening of the can lid is generally a method in which a drinking mouth made of a groove having a wedge-shaped cross section called a score is pushed into the can lid body with a tab. The score depth is controlled by the remaining score, and is built into the lid body.

  Since the aluminum can filled with the contents has a can internal pressure, a pressure strength that can withstand the internal pressure due to a temperature rise in the filling line, subsequent distribution and storage is required. In that case, if the diameter between the counter sinks is reduced, the pressure resistance improves, but on the other hand, the installation area such as the score is compressed and reduced, so it is difficult to secure the installation area such as the score and to open the drinking mouth. Therefore, there is a limit.

The pressure resistance performance of the can lid not only does not cause buckling deformation as the pressure resistance strength due to the increase in internal pressure due to the temperature rise of the contents, but also exceeds the standard pressure resistance when it is left in a high-temperature car in the summer, for example. Even if buckling is performed, it is also required that the countersink part and score are not broken and the contents are not scattered. The general pressure strength standard is, for example, 530 kPa (5.5 kgf / cm ² ) or more for beer, and this pressure strength is evaluated by the deformation start pressure when pressure is applied in the can. The buckling deformation start pressure of the can lid that is generally supplied is a pressure resistance higher than the standard pressure, and is intended to prevent cracking of the can lid by preventing buckling deformation.

Japanese National Patent Publication No. 11-505791

  The present invention has a pressure resistance capable of reliably preventing the occurrence of buckling within a specified pressure range, but when there is an increase in internal pressure exceeding that, there is no occurrence of local sharp convexity, and smooth An object of the present invention is to provide a thin can lid and a metal can for beverages provided with the can lid which do not buckle and cause the contents to scatter.

The present invention
[1] In a can lid in which an annular countersink is formed inside the chuck wall, φ2 is set to a diameter of 70 to 80% of φ1, θ1 is 30 to 60 °, and θ2 is 10 to 35 ° (however, θ1> θ2), R1 being 3 to 10 mm, a beverage metal can lid.
[However, φ1: Diameter of can lid (mm), φ2: Diameter between counter sinks (mm), θ1: Angle between chuck wall and vertical line of counter sink, θ2: Extension line of outer wall of chuck wall and counter sink , R1: A radius at a joining position between the chuck wall and the outer wall of the counter sink. ],
[2] In the above [1], θ1 is 40 to 50 °, θ2 is 15 to 25 °, and R1 is 4 to 7 mm. The above object was achieved by developing a beverage metal can provided with the can lid according to [2].

The can lid according to the present invention smoothly buckles without causing cracks when the internal pressure is extremely increased while maintaining the required pressure resistance. Once the buckling is deformed, the metal can is remarkably improved in pressure resistance, and thereafter there is no risk of cracking. It is not necessary to improve the buckling strength more than necessary, and it is possible to surely prevent the occurrence of cracks, and the thickness of the can lid can be made thinner compared to the current one, thus reducing the cost accordingly. It also has the effect of becoming.
The beverage can provided with the can lid of the present invention is left in a high-temperature automobile in summer, for example, and when the standard pressure resistance is exceeded due to an abnormal increase in internal pressure, buckling occurs smoothly, but the contents are scattered. It is possible to reliably prevent the occurrence of trouble.

The present invention was developed as a technique for preventing cracks in can lids, which is an important issue in the Japanese market.
Whereas the technical idea for the pressure strength of the conventional can lid is to prevent the cracking of the can lid by preventing buckling, the present invention minimizes the pressure strength, When the internal pressure rises as described above, it is intended to surely prevent cracking of the can lid by smoothly buckling.

  This will be described below with reference to the drawings. FIG. 2 is a plan view of a can lid in which an annular counter sink is formed inside the chuck wall, and FIG. 1 is an enlarged sectional view of the vicinity of the counter sink. That is, the diameter (φ2) between the annular counter sinks (2) is set to 70 to 80% of the diameter (φ1) of the can lid, and the vertical line (3 of the chuck wall (1) and the counter sink (2) (3) ) Is 30 to 60 °, and the angle (θ2) between the chuck wall (1) and the extension line (5) of the outer wall (4) of the counter sink (2) is 10 to 35 ° (however, θ1 > Θ2), the radius (R1) at the joining position of the chuck wall (1) and the outer wall (4) of the countersink (2) is 3 to 10 mm, preferably θ1 is 40 to 50 °, and θ2 is 15 to 25 °. , R1 is a metal can lid for beverages having a thickness of 4 to 7 mm, and a beverage can provided with the metal can lid.

  In the present invention, it is necessary to set the diameter (φ2) between the annular counter sinks to be 70 to 80% of the diameter (φ1) of the can lid, and sufficient pressure resistance performance is maintained even with a thin can lid. Is what you need to do. When the diameter of φ2 is less than 70%, the area of the central panel portion is reduced, which makes it difficult to secure a sufficient opening area and to open the can with a tab. Conversely, when it exceeds 80%, the improvement effect of pressure | voltage resistant performance cannot be expected. In particular, about 75% is preferable.

  It is necessary to set the angle θ1 between the chuck wall and the vertical line of the counter sink to 30 to 60 °. By setting the angle of θ1 within this range, while maintaining the pressure resistance of the can lid, it provides necessary buckling resistance due to an increase in internal pressure, and even when a buckling phenomenon occurs, It reliably prevents the occurrence of cracks due to deformation impact. When the angle θ1 is less than 30 °, the center panel area is increased, and the pressure resistance is reduced, so that it is difficult to form a thin can lid. The possibility of cracking in the countersink portion due to the ring phenomenon increases. A particularly preferred angle is in the range of 40-50 °.

  In the present invention, it is necessary to set the angle θ2 between the chuck wall and the extension line of the outer wall of the counter sink to 10 to 35 °. By setting this angle, the pressure resistance of the can lid is maintained and cracks from the countersink portion due to deformation impact are prevented. If the angle θ2 is less than 10 °, the effect of improving the pressure resistance cannot be expected. Conversely, if the angle θ2 exceeds 35 °, the countersink portion may crack due to the buckling phenomenon. A particularly preferred angle is in the range of 15 ° to 25 °.

  In the present invention, a particularly important requirement is to set the radius R1 at the joining position between the chuck wall and the outer wall of the counter sink to 3 to 10 mm, preferably 4 to 7 mm. As a result, when the internal pressure rises extremely, buckling is performed smoothly, and no cracks are generated at that time. When the radius R1 is less than 3 mm, the deformation impact due to the increase in internal pressure concentrates in the vicinity of R1, and there is a possibility that a crack may occur from this portion. On the other hand, when it exceeds 10 mm, the pressure resistance decreases, which is an obstacle to reducing the thickness of the can lid, which is an advantage of the present invention.

  The present invention is an organic combination of the above-described constituent elements (specific ratio of φ1 / φ2, specific angle of θ1 and θ2, specific dimension of R1), while maintaining the excellent pressure resistance performance of the can lid, In this case, the buckling is smoothly performed, and the can lid is not cracked at that time.

(Examples 1-5, Comparative Examples 1-3, Reference Examples 1-2)
Can lids comprising Examples 1 to 5, Comparative Examples 1 to 3, and Reference Examples 1 and 2 shown in the table using AA5182 alloy were produced. In addition, the structure of an Example, a comparative example, and a reference example is as follows.
-The can lid of each Example satisfied each constituent requirement of the present invention, and the lid thickness was 0.23 mm thinner than the can lid (Reference Example 1) currently employed.
-The can lid of each comparative example lacked some of the constituent requirements of the present invention, and the lid thickness was the same as that of the can lid of the present invention.
Reference Example 1 has the same dimensions as the can lid used in beverage cans currently on the market, and the lid wall thickness is 0.25 mm thicker than the can lid of the embodiment of the present invention.
Reference Example 2 uses a part (constant pressure resistance) of the constituent elements of the present invention for the can lid of Reference Example 1.
About each said can lid, the following pressure resistance evaluation test and the presence or absence evaluation of the crack generation by a buckling phenomenon were implemented, respectively. The results are as shown in the table.

A. Evaluation 1: Withstand pressure value The withstand pressure value is a buckling deformation start pressure generated in the can lid when the pressure is gradually applied to the can after the can body and the lid are wound. If this withstand voltage value is 539 kpa or more, it is evaluated that there is no practical problem.
B. Evaluation 2: Presence / absence of cracks The presence / absence of cracks was evaluated by evaluating the form of buckling deformation caused by the pressure resistance test and determining the presence or absence of cracks. The evaluation criteria were as follows.
○: No cracks are observed △: Small cracks are observed ×: Large cracks are observed

  As is clear from the above evaluation results, the can lids of Examples 1 to 5 based on the present invention were evaluated as having no problem in the pressure test and crack generation evaluation. On the other hand, the can lids shown in Comparative Examples 1 to 3 were satisfactory in the pressure resistance evaluation, but had a problem in the crack generation evaluation, and could not be put to practical use. Further, the commercially available can lid shown in Reference Example 1 is made practically free from problems by increasing the thickness. Furthermore, the can lid shown in Reference Example 2 is a type that uses the same thick wall thickness as a commercially available product and has a pressure resistance. However, a large crack is observed and it can be put to practical use. There wasn't.

  The present invention relates to a metal can lid for beverages and a metal can for beverages using the can lid, and cracks in the can lid, which is a problem in metal beverage cans, that is, the internal pressure has risen above a specified pressure. They have succeeded in developing a can lid that can smoothly buckle, improve the pressure resistance of metal cans and avoid rupture completely. Thereby, it is possible to reliably prevent the occurrence of trouble that the contents are scattered. The metal can can be widely used for general beverage metal cans such as beer and soft drinks.

Enlarged sectional view of the can lid near the counter sink Top view of can lid

Explanation of symbols

φ1: Can lid diameter (mm)
φ2: Diameter between counter sinks (mm),
θ1: Angle between chuck wall and counter sink vertical line,
θ2: Angle between the chuck wall and the extension line of the outer wall of the counter sink,
R1: Radius at the joining position between the chuck wall and the outer wall of the counter sink 1: Chuck wall 2: Counter sink 3: Counter sink vertical line 4: Outer wall of the counter sink 5: Extension line of the outer wall of the counter sink

Claims (3)

In the can lid in which an annular counter sink is formed inside the chuck wall, φ2 is set to a diameter of 70 to 80% of φ1, θ1 is 30 to 60 °, θ2 is 10 to 35 ° (where θ1> θ2 ), A metal can lid for beverages, wherein R1 is 3 to 10 mm.
Where φ1: Diameter of can lid (mm), φ2: Diameter between counter sinks (mm), θ1: Angle between chuck wall and counter sink vertical line, θ2: Extension line of chuck wall and counter sink outer wall Angle, R1: Radius at the joint position between the chuck wall and the outer wall of the counter sink The metal can lid for beverages according to claim 1, wherein θ1 is 40 to 50 °, θ2 is 15 to 25 °, and R1 is 4 to 7 mm. The metal can for drinks provided with the can lid of Claim 1 or 2.

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