JPH09202326A - Metal can - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal can which is excellent in buckling strength and stacking. SOLUTION: On the vertical cross-section of a can, a curved line C1 connecting the end of an outside circular arc 5a of the nose part 5 of a can bottom 2 and the end of the circular arc 3a of a lower body part 3 has a tangent L1 common to the outside circular arc 5a of the nose part 5 at the point of its contact with the outside circular arc 5a of the nose part 5 and, also a tangent L2 common to the circular arc 3a of the lower body part 3 at the point of its contact with the circular arc 3a of the lower body part 3. The curvature of the curved line C1 gently increases from the lower body part 3 to the nose part 5. Their relationships are defined by θ1>=θ5 and θ2>θ6, wherein θ1 is the angle of inclination on the nose side that the tangent L1 forms with a horizontal line, θ2 is the angle of inclination on the body side that the tangent L2 forms with a horizontal line, θ5 is the angle of inclination on the nose side that is obtained when the curved line is part of a circle, and θ6 is the angle of inclination on the same body side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal can, which is often used for beverages such as beer, in which the bottom of the can and the side wall of the can are integrally formed by DI processing (drawing-ironing processing), and more particularly, Regarding the shape of the can bottom.

[0002]

2. Description of the Related Art In a metal can of this type, after redrawing, ironing and can bottom forming are simultaneously performed by a DI press to form a can body, a necking process for reducing the diameter of the can and a tightening of a lid are performed. Is subjected to flanging. Since a large axial load is applied to the can body during the necking process, the flanging process, and the filling and winding process of the contents, the can body must have the required buckling strength.

FIG. 6 shows a stacking part when the conventional metal cans (21) are stacked. As shown in FIG.
(22) is provided with a downwardly convex nose portion (25),
When the cans (21) are stacked between the nose part (25) and the lower end of the lower body part (23), hit the winding part (24a) of the lower can lid (24) from the inside. A portion called a chime portion (26) for preventing the can (21) from falling is provided. In this type of metal can, the diameter of the can lid (24) tends to be reduced in order to reduce the weight. To accommodate this reduction in diameter, if the tip of the nose part (25) is moved inward without changing other dimensions,
Since the inclination angle of the chime portion (26) becomes small, there is a problem that stackability deteriorates.

FIG. 7 shows a chime portion of a conventional metal can.
An example of the vertical cross-sectional shape of (26) is enlarged, and the vertical cross-sectional shape of the chime portion (26) shows two straight line portions L3 and L4.
And a circular arc (radius R3) convex toward the inside of the can connecting the two straight line portions L3 and L4. Of the two straight line portions L3 and L4, the straight line portion L3 which is in contact with the outer arc (radius R1) (25a) of the nose portion (25) is inclined by θ3 ° with respect to the horizontal line, and the lower body portion (23) The straight line portion L4 in contact with the circular arc (radius R2) (23a) is inclined by θ4 ° with respect to the horizontal line.

FIG. 8 shows a chime portion of a conventional metal can.
Another example of the cross-sectional shape of (36) is shown in an enlarged manner.
The cross-sectional shape of the chime part (36) in (2) is the lower body part (3
It is formed by a circular arc (radius R4) (33a) of 3) and an outer circular arc (radius R1) (35a) of the nose portion (35), respectively, and a convex arc (radius R4) toward the inside of the can.
There are no straight parts on either side of this arc R4
The common tangent line L5 at the contact point of the outer arc (35a) of the nose part (35) is inclined by θ5 ° with respect to the horizontal line, and at the contact point of this arc R4 and the arc (33a) of the lower body part (33). The common tangent line L6 is inclined by θ6 ° with respect to the horizontal line.

[0006]

The conventional metal can having the chime portion (26) shown in FIG. 7 has an advantage that θ3 and θ4 can be freely determined by design, but each linear portion L3 , L4 and the circular arc, there is a problem that the buckling strength is lowered due to the rapid change of the curvature. On the other hand, with the one having the chime portion (36) shown in FIG. 8, the buckling strength can be increased by increasing the radius R4 of the circular arc, but since the sizes of θ5 and θ6 are uniquely determined, For example, there is a problem in that even if an attempt is made to increase θ5 to improve stackability, that cannot be implemented.

An object of the present invention is to provide a metal can having both buckling strength and stackability.

[0008]

In the metal can according to the present invention, in a vertical cross section of the can, a curve C1 connecting the outer arc end of the nose part of the can bottom and the arc end of the lower body part is outside the nose part. The contact point with the arc has a tangent line L1 common to the outer arc of the nose part, and the contact point with the arc of the lower body part has a tangent line L2 common to the arc of the lower body part, and the curvature of curve C1 is It increases monotonically from the lower body part side toward the nose part side, the nose side inclination angle formed by the tangent line L1 on the nose part side with the horizontal line is θ1, and the tangent line L2 on the lower body part side is formed by the horizontal line on the body side If the inclination angle is θ2, the nose side inclination angle obtained when the curve is a part of a perfect circle is θ5, and the body side inclination angle is θ6, then θ1 ≧ θ5 and θ2 ≧ θ6 (where θ1 = θ5 and θ2 = Θ6 Excluded) is characterized in that is consists.

If the curve is a part of a perfect circle,
If the end of the outer arc of the nose part and the end of the arc of the lower body part are determined, it is uniquely determined, and the curve and a part of the perfect circle in the present invention are the outer arc of the nose part. The end and the end of the arc of the lower body are commonly compared.

The curve satisfying the above condition is preferably an ellipse whose radius of curvature monotonically increases from the lower body side toward the nose side. In addition to this, there are various curves such as a parabola and a hyperbola whose radii of curvature change gradually, and some of these curves that meet the specifications are used as appropriate (see FIGS. 3, 4, and 5).

According to the metal can of the present invention, a constant θ5,
For a can having θ6, θ1 = θ5 and θ2> θ6
Then, the buckling strength is improved while maintaining the stackability,
If θ2 = θ6 and θ1> θ5, the buckling strength remains the same and stackability improves, and θ1> θ5 and θ2> θ6.
If so, both stackability and buckling strength are improved.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a stacking part when the metal cans (1) of the present invention are stacked. As shown in FIG.
The metal can (1) is placed between the nose part (5) of the can bottom (2) and the lower end of the lower body part (3) when the cans (1) are stacked on top of each other. A chime portion (6) is provided to prevent the can (1) from falling over by hitting the winding portion (4a) of 4) from the inside. The distance d between the tips of the nose (5) in the vertical cross section of the can (1) is equal to the contact diameter, and the lower body (3)
The diameter is smaller than the outer diameter D of the nose part (5) and the line connecting the tips of the nose parts (5) is horizontal.

FIG. 2 is an enlarged view of the right side portion of the vertical cross-sectional shape of the chime portion (6). The outside of the nose portion (5) is
A convex arc (radius R1) (5a) toward the outside of the can, and a lower end of the lower body (3) is a convex arc (radius R2) (3a) toward the outside of the can. (6) is a part C1 of an ellipse that is convex toward the inside of the can. Part C1 of this ellipse is a part of the second quadrant of the oblong ellipse shown by the thick line in FIG. 4, and is the arc (3a) of the lower body (3).
And the outer arc (5a) of the nose part (5) respectively, and the radius of curvature increases monotonically from the arc (3a) of the lower body part (3) to the outer arc (5a) of the nose part (5). doing.

The curve C1 of the chime part (6) is the nose part
It has a common tangent line L1 to the outer arc (5a) of the nose part (5) at the contact point with the outer arc part (5a) of (5), and at the contact point with the arc part (3a) of the lower body part (3). -It has a common tangent line L2 to the circular arc (3a) of the body part (3).
A common tangent line L between the outer arc (5a) of the nose (5) and the ellipse C1
1 is inclined by θ1 ° with respect to the horizontal line, and the common tangent line L2 between the arc (3a) of the lower body part (3) and the ellipse C1 is
It is inclined by θ2 ° with respect to the horizontal line.

When stackability (stackability) is taken into consideration, θ1 must be increased, and when buckling strength (axial load resistance) is taken into consideration, θ2 must be increased. By using an ellipse as the curve of), it is possible to first determine θ1 and θ2, and then select a suitable part C1 of the ellipse according to this.

For example, when it is necessary to reduce the ground contact diameter d without changing other dimensions, if the chime portion (6) is formed by a perfect circular arc, the inclination angle θ1 outside the nose portion (5) becomes small. The stackability deteriorates. Nose part
It is possible to keep the inclination angle θ1 outside the nose part (5) as it is by providing a straight part between the outer arc (5a) of (5) and the arc of the chime part (6). In this case, there arises a problem that buckling strength is reduced. But,
If an ellipse is used, the nose side inclination angle θ1 and the body side inclination angle θ2 are left unchanged, and the change can be made only by changing the shape of the ellipse, and the stackability does not deteriorate. Moreover, since the ellipse has a characteristic that the radius of curvature gradually changes, the buckling strength does not decrease.

[0018]

[Examples] Table 1 shows the test results of the relationship between the shape of the chime portion and the buckling strength.

The metal can is made of aluminum. In FIGS. 1 and 2, the dome depth (H) = 11.0 mm,
Contact diameter (d) = 48.0 mm, outer diameter of lower body (D) = 66.0 mm, radius of outer arc of nose (R
1) = 1.45 mm, radius of arc of lower body (R2) = 4.0 mm, inclination angle of line connecting arc end of nose part and arc end of lower body part θ0 = 43 °, These are common to the examples and comparative examples.

[0020]

[Table 1] As can be seen from Table 1, in the example in which the nose side inclination angle is 63 ° and the body side inclination angle is 28 ° in common, and the comparative example 1, the buckling strength of the example in which the curved portion shape is elliptical is 161.
Kgf, which is extremely larger than that of Comparative Example 1 having a straight line portion. As shown in Comparative Example 2, the buckling strength can be made equal to that of the example by eliminating the straight portion, but in Comparative Example 2, the nose side inclination angle is as small as 53 °, and the stackability is low. Inferior In order to ensure stackability in the same type as in Comparative Example 2 with no straight part,
As shown in Comparative Example 3, when the nose side inclination angle is 63 °, the body side inclination angle is 19.4 °, and the buckling strength thereof is greatly reduced to 132 Kgf. After all, only the example in which the curved portion has an elliptical shape can achieve both stackability and buckling strength.

To give specific dimensions of the ellipse of the above embodiment, the origin is the intersection of the vertical center line of the can (1) and the line connecting the tips of the left and right nose portions (5), and the unit is mm.
The center coordinates of the ellipse are (42.13, -2.81), the major axis a is 17.73, the minor axis b is 11.48, and the major axis inclination is 0 °.
It is. For example, the center coordinates of the ellipse are (37.23,-
2.05), the major axis a is 12.64, the minor axis b is 8.64,
By setting the inclination of the major axis to 0 °, the nose side inclination angle θ1
The angle of inclination θ2 on the body side can be set to 23 ° while maintaining 63 °, and θ1 and θ2 can be freely determined by changing the size of the ellipse.

In Table 1, it is very easy to obtain, as an embodiment, the nose side inclination angle θ1 of, for example, 60 ° and the body side inclination angle θ2 of, for example, 30 °. In addition, it can be easily estimated that both stackability and buckling strength are improved as compared with Comparative Example 2. After all, preferable conditions for the body side tilt angle, the nose side tilt angle, and the body side tilt angle are as follows.

The tangent line L1 on the side of the nose portion (5) forms a nose side inclination angle with the horizontal line, and the tangent line L2 on the lower body portion (3) side forms a body side inclination angle with the horizontal line. The curve is a perfect circle. If the nose side inclination angle is θ5 and the body side inclination angle is θ6, then θ1 ≧ θ5 and θ2 ≧ θ6 (excluding θ1 = θ5 and θ2 = θ6). Should be satisfied. For example, when θ1 = θ5 and θ2> θ6, the buckling strength is improved while the stackability remains unchanged, and θ2 = θ6 is set to θ1.
When &thgr; 5, the stackability is improved while keeping the buckling strength, and when &thgr;1>&thgr; 5 and &thgr;2>&thgr; 6, both the stackability and the buckling strength are improved.

In the above embodiment, only the case where the curved shape is an ellipse has been described, but the curved shape may be a curve other than an ellipse, for example, a parabola or a hyperbola. In short, the curve C1 of the chime part (6) is connected to the outer arc (5a) of the nose part (5) at the outer arc (5a) of the nose part (5).
It has a common tangent to the lower body (3)
Has a common tangent to the lower body part (3a) arc (3a), and the nose side tilt angle and the lower body side tilt angle satisfy the above conditions. If you have. In the parabola, as shown in FIG. 4, a part of the left half C2 of the parabola that is convex upward is shown in FIG.
As shown in, a part of the upper half C3 of the hyperbola which is convex to the left or the like is appropriately used according to the required performance. Which curve (C
1, C2, C3), the radius of curvature is preferably 5 mm or more.

The metal can in the above embodiment is made of aluminum, but a metal can made of steel
Of course, the same effect can be obtained.

[0026]

According to the metal can of the present invention, the inclination angle on the nose side is increased in consideration of stackability, and the inclination angle on the lower body side is increased in consideration of buckling strength. Therefore, stackability and buckling strength can both be achieved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a stacked portion when metal cans according to the present invention are stacked in multiple stages.

FIG. 2 is an enlarged vertical sectional view of the bottom of the metal can according to the present invention.

FIG. 3 is a diagram showing an example of a curve suitable for forming the cross-sectional shape of the chime portion of the metal can bottom portion according to the present invention.

FIG. 4 is a diagram showing another example of curves suitable for forming the cross-sectional shape of the chime portion of the metal can bottom portion according to the present invention.

FIG. 5 is a view showing still another example of a curve suitable for forming the cross-sectional shape of the chime portion of the metal can bottom portion according to the present invention.

FIG. 6 is a vertical cross-sectional view showing a stacking portion when the conventional metal cans are stacked in multiple stages.

FIG. 7 is an enlarged vertical sectional view showing an example of a conventional metal can bottom portion.

FIG. 8 is an enlarged vertical sectional view showing another example of the conventional metal can bottom portion.

[Explanation of symbols]

 (1) Metal can (2) Can bottom (3) Lower body (3a) Lower body arc (5) Nose (5a) Nose outside arc

Claims (1)

[Claims] 1. In the vertical cross section of the can (1), the outer arc (5a) end of the nose part (5) of the can bottom (2) and the lower body part (3).
The curved line C1 connecting the end of the arc (3a) of the nose part (5) has a contact point with the outer arc (5a) of the nose part (5).
Has a common tangent line L1 with the lower body
At the contact point with the arc (3a) of (3), the lower body (3)
Has a common tangent line L2 with the arc (3a) of
The tangent line L1 on the (5) side is the nose side tilt angle with the horizontal line is θ
1. The body side inclination angle formed by the tangent line L2 on the lower body part (3) side to the horizontal line is θ2, and the nose side inclination angle obtained when the curve is a part of a perfect circle is θ5, and the body side inclination angle is Is θ6, and θ1 ≧ θ5 and θ2 ≧ θ6 (excluding θ1 = θ5 and θ2 = θ6).