JP6946620B2 - Method of forming curl portion of can body and can body mouth - Google Patents

Description

The present invention relates to a method for forming a curl portion of a can body and a can body mouth portion.

A can body having a mouth portion is generally used as a container for a liquid container such as drinking water, and a curl portion having an open end wound into a curl shape is formed in the mouth portion sealed with a cap. .. In particular, bottle cans are made by forming a metal plate made of aluminum or its alloy into a bottomed tubular body by drawing and ironing, and then performing neck-in processing on the opening of the bottomed tubular body. A reduced diameter mouth is formed, and the mouth is thread-molded and curled.

Various processed shapes have been proposed for the curl portion formed at the mouth portion of the can body in consideration of the sealing property of the cap attached to the mouth portion with the sealing material.

For example, in the prior art described in Patent Document 1 below, an outer side wall portion in which a curl portion formed by folding the peripheral edge of an opening radially outward extends in a direction substantially parallel to the can axis direction of a bottle can. The outer side wall portion is provided with an outer surface side convex portion extending radially inward from the upper end of the outer surface side wall portion and an inner surface side convex portion extending radially inward from the outer surface side convex portion, and the outer surface side wall portion has a predetermined length or more. In addition, a shape is shown in which the connection portion between the outer side wall portion and the outer surface side convex portion, which is formed linearly by crushing, is separated from the upper end (upper end of the mouth portion) of the bottle can. There is.

Further, in the prior art described in Patent Document 2 below, the curl portion of the outer winding is formed to have a curved surface whose outer surface protrudes outward without performing curl crushing processing, and the vertical cross-sectional shape of the curl portion is formed. Is shown to be formed so as to be a vertically long oval.

Japanese Unexamined Patent Publication No. 2004-217305 Japanese Unexamined Patent Publication No. 2006-188279

In the prior art described in Patent Document 1 described above, a curl portion is formed by a combination of a curved flange processing (spinning molding) and a linear crushing process. At this time, the lower end of the outer side wall portion formed by the linear crushing process is a free end, and a relatively large gap is formed between the outer peripheral surface and the outer peripheral surface of the mouth portion (mouthpiece portion) of the bottle can. .. According to such a conventional technique, when a drop impact is applied in a state where the mouth portion is sealed with a cap after filling the can body with the contents, the gap between the lower end of the outer side wall portion and the outer peripheral surface of the mouth portion is adjusted. As a result, the curl portion is deformed, and this deformation may cause a problem that the desired sealing property cannot be obtained at the sealing point.

On the other hand, in the prior art described in Patent Document 2 described above, a curl portion that is curved as a whole is formed without crushing, and the lower end of the curl portion is brought close to the outer peripheral surface of the mouth portion. There is. However, since the curl portion having a vertically long oval cross-sectional shape is not shaped to withstand a drop impact, the mouth portion is sealed with a cap after filling the can body with the contents. In this state, when a drop impact is applied, the curled portion is deformed so that the cross-sectional shape is crushed, and this deformation may cause a problem that the desired sealing performance cannot be obtained.

An object of the present invention is to solve such a problem of the prior art, and the shape of the curl portion is such that a desired sealing performance can be obtained for the cap attachment, and the cap is dropped. It is an object of the present invention to suppress deformation of the curl portion due to an impact.

In order to solve such a problem, the can body according to the present invention has the following configuration.
A can body having a mouth portion and a curl portion provided at the open end of the mouth portion, and the curl portion has an upper end curved portion including the upper end portion of the mouth portion and a lower end close to a side wall of the mouth portion. Alternatively, an outer wall curved portion whose upper portion is inclined outward with respect to the can axis, an inner connecting curved portion provided inside the upper end curved portion and having a radius of curvature smaller than the radius of curvature of the upper end curved portion, and the above. A can body provided outside the upper end curved portion and having an outer connecting curved portion having a curvature smaller than the radius of curvature of the upper end curved portion.
Further, the method for forming a curl portion of the mouth portion of a can body according to the present invention is a method of forming a curl portion at the opening end of the mouth portion of a can body having a bottom portion, a body portion, a shoulder portion and a mouth portion. It is characterized in that a portion below the maximum outer diameter portion of the curl portion is curved and molded by crushing.

The can body of the present invention having such characteristics has a curled portion having a cross-sectional shape that is resistant to a drop impact. As a result, the shape of the curl portion can obtain the desired sealing performance for the cap attached to the mouth portion, and the deformation of the curl portion due to the drop impact can be suppressed.
Further, according to the curl portion forming method of the present invention, the portion below the maximum outer diameter portion of the can body curl portion has a shape that is resistant to a drop impact, or a desired sealing performance with respect to a cap that adheres to the mouth portion. Can be molded into a shape that can be obtained.

It is explanatory drawing which showed the structural example of the can body (overall composition drawing). It is a vertical cross-sectional view which showed the curl part of the can body which concerns on embodiment of this invention. It is a vertical cross-sectional view which showed the sealability of the curl part and the cap of the can body which concerns on embodiment of this invention. It is explanatory drawing which showed the method of forming the curl part in the mouth part of the can body which concerns on embodiment of this invention ((a) is the state before processing, (b) is in the process of spinning molding, (c) is spinning molding. After molding, (d) shows the molding process of the crushing process, respectively).

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals in different figures indicate parts having the same function, and duplicate description in each figure will be omitted as appropriate.

FIG. 1 shows a configuration example of the can body 1. The can body 1 is, for example, a metal container having a bottom portion 1A, a body portion 1B, a shoulder portion 1C, and a mouth portion 1D. An example of the can body 1 is a bottle can. The method of forming a bottle can is as follows. For example, a metal plate made of an aluminum alloy or the like is punched into a circular shape, which is drawn to obtain a bottomed cylindrical cup member, which is then re-drawn and ironed to form a cylindrical can with a predetermined wall thickness. Once. Then, by neck-in processing, a predetermined length is reduced from the open end of the cylindrical can to form the shoulder portion 1C and the mouth portion. Then, a bead portion and a screw portion are formed in the mouth portion by spinning processing, and then a side wall (side wall 2 described later) inclined upward and inward is formed above the screw portion by neck-in processing, and the side wall is formed. A bottle-shaped can body 1 having a mouth portion 1D is obtained by forming a curl portion 10 described below at the upper open end by spinning processing.

The curl portion 10 is a portion where the open end of the mouth portion 1D is curved outward and processed into a curl shape. The curl portion 10 is formed in an annular shape around the mouth portion 1D with substantially the same cross section.

The curl portion 10 provided in the mouth portion 1D of the can body 1 according to the embodiment of the present invention has a cross-sectional shape as shown in FIG. 2 (in the figure, P1 is a virtual line parallel to the can axis. ). That is, in the curl portion 10, the upper end curved portion 11 including the upper end of the mouth portion 1D and the lower end 12A are close to or in contact with the side wall 2 of the mouth portion 1D, and the upper portion is inclined outward with respect to the can axis (virtual line P1). The outer wall curved portion 12 is provided, and the cross-sectional shape thereof is a substantially inverted triangular shape having the side wall 2 of the mouth portion 1D, the upper end curved portion 11, and the outer wall curved portion 12 as three sides.

The cross-sectional shape of the curl portion 10 is structurally resistant to a drop impact. To show a specific structure, an inner connecting curved portion 13 is provided inside the upper end curved portion 11, and an outer connecting curved portion 14 is provided on the outer side of the upper end curved portion 11, and the inner connecting curved portion 13 is provided. The radius of curvature R2 and the radius of curvature R3 of the outer connecting curved portion 14 are both formed to be smaller than the radius of curvature R1 of the upper end curved portion 11, and form a substantially inverted triangular corner portion.

More specifically, in the curl portion 10, the side wall 2 of the mouth portion 1D above the lower end 12A of the outer wall curved portion 12 is inclined inward with respect to the can axis (virtual line P1). By inclining the side wall 2 of the mouth portion 1D in this way, an eccentric load in the F direction shown in the drawing can be received by this inclination, so that the curl portion 10 having such a cross-sectional shape has high resistance to an eccentric load. have.

Further, more specifically, it is preferable that the curl portion 10 is formed so that the radius of curvature of the upper end curved portion 11 and the outer wall curved portion 12 is substantially the same. According to this, the substantially inverted triangular shape due to the cross-sectional shape of the curl portion 10 becomes a substantially equilateral triangle, and has equal resistance to impact loads received from various directions. At this time, the outer connecting curved portion 14 becomes the maximum outer diameter portion 14A in the curl portion 10.

FIG. 3 shows an example of a sealing structure of the curl portion 10 when the cap 3 is attached to the mouth portion 1D of the can body 1. When the cap 3 is attached to the mouth portion 1D, the curl portion 10 having the above-mentioned cross-sectional shape forms a seal point by the outer connecting curved portion 14 biting into the sealing material (liner material) 3A of the cap 3. And good sealing performance can be obtained. At this time, by making the radius of curvature R3 of the outer connecting curved portion 14 smaller than the radius of curvature R1 of the upper end curved portion 11 and setting it within an appropriate range, a curl that can obtain a desired bite while preventing damage to the sealing material 3A. The shape of the portion 10 can be formed.

Further, when the can body 1 is in a positive pressure state, a force for moving away from the upper end of the mouth portion 1D always acts on the cap 3, but according to the cross-sectional shape of the curl portion 10, it becomes a seal point. Since the outer wall curved portion 12 extending downward from the outer connecting curved portion 14 is inclined inward, the portion below the outer connecting curved portion 14 that bites into the sealing material 3A prevents the cap 3 from being lifted by positive pressure. Since it has a locking action to stop it, an effective sealing effect can be obtained even when the can body is in a positive pressure state.

FIG. 4 shows an example of a method of forming the curl portion 10. (A) shows the open end 1D1 before processing. Spinning molding as shown in (b) and (c) is performed on the open end 1D1 as the first stage processing. Specifically, as shown in (b), by pressing the first spinning die 20 from above, curved flange forming (spinning forming) is performed on the open end 1D1. At this time, the curved shape (radius of curvature R1) of the upper end curved portion 11 in the curled portion 10 is formed by the curved mold 20A of the first spinning die 20. Next, as shown in (c), by pressing the second spinning die 21, the inner connecting curved portion 13 formed inside the upper end curved portion 11 is formed. At this time, the curved shape (radius of curvature R2) of the inner connecting curved portion 13 is formed by the curved type 21A of the second spinning die 21.

After that, as the second stage processing, as shown in (d), the reform tool 22 is pressed from the side to perform crushing processing. By this crushing process, the outer wall curved portion 12 which is a portion below the maximum outer diameter portion of the curl portion 10 is curved and molded. At this time, since the reform tool 22 has a mold surface 22A whose upper side is inclined outward with respect to the rotation center axis and is curved, a part of the outer wall curved portion 12 formed by this is crushed. As a result, the remodeling tool 22 has a rotation center axis and a curved molded surface whose lower side is inclined inward with respect to the can axis (virtual line P1).

As described above, molding the curl portion 10 by a combination of spinning molding and crushing is already known as shown in the prior art, but in the forming method of the present invention, the reform tool used in crushing is used. One of the features is that the mold surface 22A of the 22 is a curved surface whose upper side is inclined outward with respect to the rotation center axis. By using such a reform tool 22, the cross-sectional shape of the curl portion 10 can be made into an effective substantially inverted triangular shape having resistance to a drop impact.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the design changes, etc. within the range not deviating from the gist of the present invention, etc. Even if there is, it is included in the present invention. Further, each of the above-described embodiments can be combined by diverting the technologies of each other as long as there is no particular contradiction or problem in the purpose and configuration thereof.

1: Can body, 1A: bottom, 1B: body, 1C: shoulder, 1D: mouth,
2: Side wall, 3: Cap, 3A: Sealing material,
10: Curled part, 11: Upper end curved part, 12: Outer wall curved part, 12A: Lower end,
13: Inner connecting curved part, 14: Outer connecting curved part

Claims (4)

A can body having a mouth portion and having a curl portion at the open end of the mouth portion.
The curl part is
An upper end curved portion including the upper end of the mouth portion and an upper end curved portion
An outer wall curved portion whose lower end is close to or abuts on the side wall of the mouth portion and whose upper end is inclined outward with respect to the can shaft.
An inner connecting curved portion provided inside the upper end curved portion and having a radius of curvature smaller than the radius of curvature of the upper end curved portion,
It has an outer connecting curved portion provided outside the upper end curved portion and having a radius of curvature smaller than the radius of curvature of the upper end curved portion.
The mouth portion is provided with a screw portion and has a screw portion.
The upper end curved portion is located above the inner connecting curved portion and the outer connecting curved portion .
Cross-sectional shape of the curled portion is the outer wall curved side wall of the mouth portion and the upper curved portion and a substantially inverted triangular shape to three sides, the upper curved portion is shaped der Rukoto curved upwards Characteristic can body. The side wall of the mouth portion of the upper than the lower end of the outer wall curved section, the can body according to claim 1 Symbol mounting, characterized in that the upper is inclined inwardly relative to the can axis. The can body according to claim 1 or 2 , wherein the radius of curvature of the upper end curved portion and the outer wall curved portion are substantially the same. The can body according to any one of claims 1 to 3 , wherein the outer connecting curved portion serves as the maximum outer diameter portion of the curled portion.

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