JPH08156929A - Beverage can - Google Patents

Abstract

PURPOSE: To provide a beverage can with a neck part which can be made thinner, and of which the axial compression strength is high by a method wherein the shape of the vertical cross section of the neck part of a can body is formed into a shape with an arc which protrudes inward on the lid side, and an arc which protrudes outward on the body side. CONSTITUTION: For a beverage can wherein the diameter of a can lid is smaller than the diameter of a can body, the shape of the vertical cross section of a neck part 3 which is formed on a can body part and extends from a body part 2 to a lid part 1 is formed into a shape with an arc 4 which protrudes inside of the lid 1 side and an arc 5 which protrudes outside of the body 2 side, and at the same time, a neck line to connect both arcs 4, 5 is formed of a curved line which comes into contact with both arcs 4, 5 and protrudes outside. By forming the shape of the vertical cross section of the neck part 3 into such a shape, the axial compression strength is increased, and in addition, the thickness of the neck part 3 is made thinner than a conventional type neck, and the weight of the can is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beverage can having a smaller can lid diameter than the can barrel diameter, and more particularly to the shape of a neck portion formed in the can barrel portion of the beverage can from the barrel portion to the lid portion. It is a thing.

[0002]

2. Description of the Related Art Conventionally, in a beverage can having a can lid diameter smaller than a can body diameter, the neck portion has a stepped neck,
A smooth neck, and an intermediate neck between them, is adopted. As shown in FIG. 5a, the stepped neck has a conical neck portion 3 between the can lid side 1 and the can body side 2 which is formed in a stepwise shape in the longitudinal sectional shape, while the smooth neck is As shown in FIG. 5b, the neck portion 3 is formed in a conical shape between the arc 4 on the can lid side 1 and the arc 5 on the can body side 2 in the longitudinal sectional shape.

[0003]

By the way, from the viewpoint of cost and resource saving, beverage cans have been conventionally required to be light in weight, and efforts to reduce the plate thickness of each portion of the beverage can are being continued at present. On the other hand, the neck portion of the beverage can withstands a compressive load in the axial direction (longitudinal direction of the can) (hereinafter referred to as an axial compressive load) when the can lid is wound around the can body, so The actual condition is that the plate thickness is slightly thicker than that of the other. Therefore, the present inventors have paid attention to the plate thickness of the neck portion in order to reduce the weight, and have considered reducing the plate thickness of this portion. However, when the neck portion has a stepped neck, since the stepped neck has steps as compared with the smooth neck, the absolute length of the neck portion becomes long, which is not suitable for weight reduction. On the other hand, since the smooth neck has no steps, the neck length is short and the neck shape is the most advantageous for promoting weight reduction, but when the plate thickness becomes thin, the axial compressive strength decreases and the It is expected that they cannot withstand axial compressive loads.

In view of the above circumstances, the present invention has been made by improving the shape of the smooth neck, which is the most advantageous neck shape for promoting the weight reduction of beverage cans.
It is an object of the present invention to provide a beverage can having a neck portion having a high axial compressive strength that can be thinned.

[0005]

In order to achieve the above object, a beverage can according to the present invention has a vertical cross-sectional shape of a neck portion formed on the can body portion side from a body portion to a lid portion. It has a convex arc inside the part side and a convex arc outside the body part side, and a neckline connecting both arcs is in contact with both arcs and is formed by a curved curve outward. .

[0006]

After the present inventors have found the above-mentioned problems, FIG.
2. A conventional type smooth neck shown in FIG. 2 and a neck portion 3 based on the conventional smooth neck having an outwardly convex arc 6 shown in FIG. 1, and a longitudinal section having an internally convex arc 7 shown in FIG. Assuming the neck portion 3 of No. 3, the plastic collapse mode was obtained by a numerical analysis method (finite element method) based on these. The target can shape is usually commercially available 3
Aluminum beverage can for 30ml, average body diameter D = 66
mm, height of neck (axial distance between BCs in the figure)
Is about 13 mm. Further, the plate thickness of the body portion and the neck portion are the same. In the figure, r ₁ : radius of arc 4 on can lid side 1, r ₂ : radius of arc 5 on can body side 2, r ₃ : radius of arc 6, r ₄ : radius of arc 7, point B: Contact point between arc 4 and body side neck, point C: Contact point between arc 5 and body side neck,
α: Angle formed by a line connecting the centers O ₂ and O ₃ of the arcs 5 and 6 and a line connecting the center O _{2 of the} arcs 5 and the point C, δ: Centers O ₁ and O of the arcs 4 and 7 _The angles formed by the line connecting 4 and the center O _{1 of the} arc 4 and the line connecting the points B are shown respectively.

FIG. 3 shows the plastic collapse mode obtained by the above for a conventional type smooth neck. The weakest part against the axial compression load exists on the arc 5 side of the can body side 2 of the neck part 3. . Thus, the weakest part is arc 5.
The reason for existing on the side is that a large outward force is applied to the contact point between the arc 5 and the conical portion (straight line), so that the contact point first collapses near the contact point. Further, in the comparative example having the convex arc 7 shown in FIG. 2, the weakest portion against the axial compressive load existed in the substantially central portion of the neck portion 3, although not shown. It is considered that the reason why the weakest portion is present in the substantially central portion of the neck portion 3 is that the arc 7 is convex inward and thus easily bends when an axial compressive load is applied. Therefore, the axial compressive load at the time of plastic collapse was plastically collapsed at a value smaller than that in the case of the conventional type smooth neck.

On the other hand, FIG. 4 shows FIG. 1 according to the present invention.
7 shows a plastic collapse mode in the case of having an outwardly convex arc 6, where the weakest part against axial compression load is the neck part 3
It existed on the arc 4 side of the can lid side 1. The reason why the weakest part is on the side of the arc 4 is that the arc 6 is convex outward and is in contact with the arc 5, so that the rising angle on the can barrel side is larger than that of the conventional type smooth neck. ,
This is because a small outward force acts on the central portion of the arc 6 or on the arc 5 side, and the can body side is strengthened. In the vicinity of the contact points of arc 4 and arc 6, the angle of the neck is rather small compared to the conventional type smooth neck, which is disadvantageous in strength compared to the conventional type, but this part originally has a large plate thickness / radius and strength level. Therefore, the maximum axial compression strength is higher than that of the conventional type smooth neck described above and the comparative example having the convex arc 7 shown in FIG.

[0009]

EXAMPLE A numerical analysis method (finite element method) was performed based on the neck shape shown in FIG. 1, the neck shape shown in FIG. 2 and the conventional type smooth neck shown in FIG. The load was calculated. At this time, the plate thickness is 0.16 mm, the radii of the arcs 4 and 5 are r ₁ = 9 mm and r ₂ = 5 mm as standard values of the current smooth neck, respectively.
In the model with 28 kgf / mm ² , the radius r ₃ of the arc 6 and the radius r _{4 of the} arc 7 were changed to the values shown in Table 1 and numerically analyzed. As described above, α and δ in Table 1 are the center of the arc 5 and the line connecting the centers O ₂ and O ₃ of the arc 5 and the arc 6.
The angle formed by the line connecting O ₂ and point C, δ is arc 4 and arc 7.
A center O _1, the angle formed between the center O ₁ and B connecting it to point lines O ₄ connecting lines and arcs 4, was determined to correspond to the case of changing the r ₃ and r _4, respectively It is a value.

The maximum axial compression load obtained by this analysis,
Table 1 also shows the increase / decrease value of the maximum axial compression load of the present invention example and the comparative example based on the maximum axial compression load of the conventional type smooth neck as the improvement rate.

[0011]

[Table 1]

As is clear from Table 1, the maximum axial compressive load is lower than that of the conventional type smooth neck (No. 5) in the comparative neck shapes (No. 6 and 7) having a convex arc inside. On the other hand, in the neck shape (No. 1 to 4) of the present invention example having an outwardly convex arc, the maximum axial compression load is higher than that of the conventional type smooth neck, and the improvement rate is up to 15%. (No.3) Further, in the present invention, it is preferable to set the angle α, which is the reference for drawing an outwardly convex arc, in the range of 10.5 ° to 17.5 °, and in this range, the improvement rate compared to the conventional type smooth neck. With the expectation that the axial compressive strength will be increased by 10% or more, the thickness of the neck can be reduced. Incidentally, in the neck shape of No. 3 of the present invention example, the plate thickness which becomes the same maximum axial compression load (201 kgf) as the conventional type is 0.14.
The thickness was 4 mm, and the thickness reduction rate was 10%.

[0013]

As described above, in the beverage can according to the present invention, the inside arc of the lid and the outside arc of the body contact the both arcs, and Since it is connected by a curved neckline to the outside, the axial compressive strength can be increased, and the plate thickness of the neck portion can be made thinner than the current smooth neck, and the weight of the can can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a neck portion of a beverage can according to the present invention.

FIG. 2 is a schematic vertical sectional view of a neck portion of a beverage can of a comparative example.

FIG. 3 is a plastic collapse mode diagram obtained for a smooth neck of a conventional beverage can.

FIG. 4 is a plastic collapse mode diagram obtained for a neck portion of a beverage can according to the present invention.

FIG. 5 is a schematic vertical sectional view of a neck portion of a conventional beverage can, where a is a stepped neck and b is a smooth sectional vertical section.

[Explanation of symbols]

1: Can lid side 2: Can body side 3: Neck part 4: Can lid side arc 5: Can barrel side arc 6: Outward convex arc 7: Inner convex arc r ₁ : Can lid side arc Radius r ₂ : Radius of arc on can barrel side r ₃ : Radius of arc on convex outside r ₄ : Radius of arc on convex inside O ₁ : Center of arc on can lid side O ₂ : Arc on can barrel side Center O ₃ : Center of an outwardly convex arc O ₄ : Center of an inwardly convex arc

Claims (1)

[Claims] 1. A vertical cross-sectional shape of a neck portion extending from a body portion to a lid portion formed on a can body portion has an inner convex arc on the lid side and an outer convex arc on the body side. A beverage can, characterized in that a neckline connecting the two arcs is in contact with the arcs and is formed by a curved line protruding outward.