JP4239606B2 - Metal container forming method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming a metal container having a metal mouth-and-neck portion that can be resealed by a cap, and more particularly, to a rust prevention technique for a curled portion provided at an opening edge of the mouth-and-neck portion.
[0002]
[Prior art]
[Patent Document 1]
JP, 2002-225864, A As a conventional metal container of this kind, for example, the one described in Patent Document 1 is known. That is, a container body, and a metal mouth and neck portion that protrudes from the container body and from which a reseal cap can be attached and detached, and has an annular curl portion that is wound outward on the opening edge of the mouth and neck portion. ing.
[0003]
This metal container uses a steel plate coated on both sides with a resin film, but the tip of the curled portion is a cut end surface where the metal surface is exposed, and there is a possibility of rusting when moisture adheres. Therefore, a curable coating film is coated on the portion where the curled portion and the mouth and neck portion abut.
[0004]
[Problems to be solved by the invention]
However, in the metal container described in Patent Document 1 described above, when the curled portion is deformed due to a load or thermal expansion when the cap is tightened, a large shear stress acts on the adhesion surface of the coating film, and it is easy to peel off. There is a problem that defects are likely to occur.
[0005]
The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a method for forming a metal container having a highly sealed curl portion.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the metal container molding method of the present invention includes a resin film to be used as a sealing material at a predetermined location on the outer surface of a curled cylinder portion that is to become a curled portion before the curled portion is formed. It is characterized in that the resin film is wound around the curled part in a curling step and the gap between the tip part of the curled part and the outer surface of the mouth and neck part is sealed.
[0007]
In another metal container forming method, after the curl portion is initially curled, a resin film to be a sealing material is attached in advance to a predetermined portion of the outer surface of the mouth neck portion, and the resin film is formed in a subsequent curling process. It is characterized by being wound around the curled portion and sealing the gap between the tip of the curled portion and the outer surface of the mouth and neck.
Further, in each of the metal container forming methods, the cut end surface of the curled portion is covered with a sealing material.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below based on the illustrated embodiments.
FIG. 1 shows an example of a metal container formed by the forming method of the present invention.
The metal container 1 includes a container main body 10 and a metal mouth and neck portion 20 that protrudes from the container main body 10 and to which a reseal cap 50 can be attached and detached. An annular curled portion 30 is provided.
A sealing material 40 is interposed in an annular gap between the curled portion 30 and the outer surface of the mouth-and-neck portion 20, and the gap is sealed by the sealing material 40.
[0009]
The container main body 10 includes a cylindrical body portion 11 having a bottom and a shoulder portion 12 that is inclined inwardly upward from the upper end of the body portion 11, and the mouth and neck portion 20 protrudes from the shoulder portion 12. The container body 10 and the mouth / neck portion 20 have a structure that is integrally formed by drawing from a single blank. The blank is made of a multi-layered material in which the front and back surfaces of a thin steel plate are coated with a resin.
[0010]
The mouth-and-neck portion 20 includes a large-diameter screw cylinder portion 21 in which a male screw 21 a is formed, an open cylinder portion 22 that is narrowed to a small diameter from the upper end of the screw cylinder portion 21, and a space between the screw cylinder portion 21 and the open cylinder portion 22. The step part 23 to connect is provided. The step portion 23 is an inclined wall that is inclined downward by a predetermined angle from the lower end of the opening tube portion.
[0011]
The curled portion 30 has an upper curved portion 31 that is curved upward and convex upward from the upper end of the opening cylinder, and a convex shape that is curved downward from the outer diameter end of the upper curved portion 31 radially inward. A lower bending portion 32 that bends. The upper curved portion 31 has a semicircular shape, and the lower curved portion 32 has a ¼ arc shape. The portion from the midway position to the tip (inner diameter end) of the lower curved portion 32 has a predetermined gap with the step portion 23. Are facing each other.
[0012]
In this embodiment, the sealing material 40 is interposed in an annular gap between the lower curved portion 32 and the step portion 23 of the curled portion 30. Further, the cut end surface 33 where the metal surface is exposed is located at the inner diameter end of the lower curved portion 31 by the seal material 40, and the cut end surface is covered with the seal material 40.
[0013]
As the sealing material 40, a rubber-like elastic material such as a so-called sealing compound is used, and is sandwiched between the lower curved surface 32 of the curled portion 30 and the shoulder portion of the mouth and neck portion in a compressed state. .
Examples of the main material of the compound include styrene butadiene rubber, butadiene rubber, ethylene propylene rubber, ethylene propylene diene rubber, polyisoprene rubber, butyl rubber, nitrile butadiene rubber, chloroprene rubber, polyurethane rubber, acrylic rubber, epoxy rubber and the like. Used. In addition, a polyamide resin, for example, a resin such as a polyamide resin, a polyolefin resin, or ethylene vinyl acetate copolymer (EVA) can be used as the main material of the compound.
[0014]
The cap 50 includes a cap cylinder 51 formed with a female thread that engages with the screw cylinder part 21 of the mouth-and-neck part 20, and a top plate part 52 that is in close contact with the top of the curl part 30 when tightened. Various caps such as a cap and a resin cap are applicable.
In the metal container of the present embodiment, even when the curled portion 30 is deformed when the cap is attached or detached or due to thermal expansion, the deformation is absorbed by the sealing material 40 and the sealing performance is maintained.
[0015]
2 to 4 show a method for forming the metal container. In either case, the sealing material 40 is incorporated when the curled portion 30 is formed.
FIG. 2 is a reference example of the metal container forming method that is not the present invention. FIG. 2A shows a curl forming cylinder portion 300 at the upper end of the neck portion 20 before the curling step for forming the curl portion. Is extended by a predetermined length.
In this state, a compound 41 to be a ring-shaped sealing material 40 is attached to a predetermined portion on the outer surface of the mouth-and-neck portion 20, in this embodiment, over the upper surface of the stepped portion 23 and the base of the curl forming cylinder portion 300.
[0016]
In this embodiment, the curling process is divided into three stages (see FIGS. 2B, 2C, and 2D). At the final stage, the lower curved portion 32 comes into contact with the compound 41 and curls. And the gap between the lower curved portion 32 and the stepped portion 23 and the open cylindrical portion 22 is sealed (see FIG. 2D).
[0017]
FIG. 3 shows an embodiment of the present invention in which a predetermined portion of the outer surface of the mouth-and-neck portion 20 is formed before the curled portion 30 is formed, that is, a predetermined portion of the curled cylindrical portion 300 that should be a curled portion in this embodiment. This is an example in which a cylindrical resin film 42 to be the sealing material 40 is mounted.
In the curling step, the resin film 42 is wound around the curled portion 30 and deformed, and the curled portion 30 is in a state where a part 40a of the sealing material 40 covers the cut end surface 33 of the curled portion 30 as shown in FIG. The remaining portion 40b that is filled inside and does not fit into the curled portion 30 remains on the outer surface of the stepped portion 23 from the outer periphery of the open cylindrical portion 22. The sealing range of the sealing material after molding the curled part can be adjusted by the length of the resin film 42, the mounting position, and the like.
As a material of the resin film 42, polypropylene, low density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-propylene copolymer, polystyrene, acrylonitrile-butadiene-styrene resin, ethylene acetate pi copolymer, polyethylene terephthalate, polyethylene Naphthalate, polybutylene terephthalate, etc. can be used.
[0018]
FIG. 4 shows a molding method in which a resin film 42 as a sealing material is attached to a predetermined portion after the initial curl molding, in contrast to the molding method of FIG.
4A shows a state before the curling process for forming the curled portion 30, and FIG. 4B shows a state where the initial curl molding has been performed. In a state where the curl is initially formed, a resin film 42 which is formed into a cylindrical shape to be the sealing material 40 is attached to a predetermined portion of the curled cylindrical portion 300.
[0019]
The resin film 42 is mounted below the initial curl portion 301 and has a shorter length than the example shown in FIG. In the subsequent curling process (see FIGS. 4C and 4D), the resin film 42 is wound around the curled portion 30 and further compressed by the curling molding pressure, and the lower curved portion 32, the stepped portion 23, and the open cylindrical portion 22 are compressed. Is sealed (see FIG. 4D). Also in this case, a part 40a of the sealing material 40 covers the cut end surface 33 of the curled part 30, and the remaining part 40b is the lower curved part 32 of the curled part 30, the step part 23 of the mouth-and-neck part 20, and the opening cylinder. The gap between the portions 22 is sealed.
Also in this case, compared with the case where the resin film 42 is mounted before the curl molding as shown in FIG. 3, the tip position of the curled portion 30 and the position of the resin film 42 can be set accurately.
[0020]
In the embodiment shown in FIG. 2, a resin film that is formed in an annular shape may be mounted instead of the compound 41.
Further, in the above embodiment, the engagement between the mouth neck and the cap is not limited to the screw engagement, and may be an uneven engagement that can get over the unevenness or other engagement methods.
[0021]
【The invention's effect】
As described above, the following effects can be obtained in the present invention.
[0022]
According to the first aspect of the present invention, before molding the curled portion, a resin film is attached in advance to a predetermined portion of the outer surface of the mouth-and-neck portion, and the resin film is wound around the curled portion in a curling process, so Since the gap between the outer surface of the neck and the neck of the mouth and neck is sealed, the curling portion and the neck of the mouth and neck can be sealed simultaneously with the curling, and a sufficient sealing surface pressure can be obtained by the curling pressure.
In addition, the curl portion can be filled with a sealing material, and moisture can be prevented from entering the curl portion.
[0023]
According to the second aspect of the present invention, after the curl portion is initially curled, a resin film to be a sealing material is previously attached to a predetermined portion of the outer surface of the mouth and neck portion, and the resin film is turned into the curl portion in a subsequent curling process. Since the gap between the front end of the curled portion and the outer surface of the mouth and neck is sealed, it is possible to seal between the curled portion and the mouth and neck simultaneously with curling, and to obtain a sufficient sealing surface pressure by the curling pressure. it can.
Further, by mounting the resin film after the initial curl molding, the positional relationship between the curled portion and the sealing material can be set more accurately.
[0024]
According to the third aspect of the present invention, in the first or second aspect, since the cut end surface of the curled portion is formed by the sealing material, the cut end surface of the curled portion is reliably protected.
[Brief description of the drawings]
FIG. 1 shows a metal container according to an embodiment of the present invention, in which FIG. 1 (A) is a sectional view of the main part of the mouth and neck, and FIG. 1 (B) is an overall front view.
2A to 2D are explanatory views of a reference example of the curling process of the mouth and neck of FIG.
FIG. 3 (A) is a cross-sectional view of the main part of the metal container according to the embodiment of the present invention in a state where a film-like sealing material is attached before curling of the mouth and neck, and FIG. 3 (B) is the same figure. It is principal part sectional drawing after the curling of (A).
FIGS. 4A to 4D are explanatory views of a curling process of the mouth and neck of a metal container according to another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Metal container 10 Container main body 11 Trunk part, 12 shoulder part 20 Mouth neck part 21 Screw cylinder part, 22 Open cylinder part, 23 Step part 30 Curl part 31 Upper curved part, 32 Lower curved part, 33 Cutting end surface 40 Sealing material 42 Resin film 300 Curl molding cylinder part 301 Initial curl part

Claims (3)

A metal container having a container main body and a mouth neck that protrudes from the container main body and from which a reseal cap can be attached and detached, and has an annular curl wound outwardly around the opening edge of the mouth neck; Before molding the curled part, attach a resin film to be a sealing material to a predetermined place on the outer surface of the mouth and neck part beforehand,
A molding method for a metal container, wherein a resin film is wound around a curled portion in a curling step to seal a gap between a tip portion of the curled portion and an outer surface of the mouth and neck portion. In a metal container having a container main body and a mouth neck that protrudes from the container main body and from which a cap for reseal can be attached and detached, and has an annular curled portion wound outward on the opening edge of the mouth neck,
After the initial curl molding of the curled part, a resin film to be a sealing material is attached to a predetermined portion of the outer surface of the mouth neck in advance,
A method for forming a metal container, comprising enclosing a resin film in a curled portion in a subsequent curling step to seal a gap between a tip portion of the curled portion and an outer surface of the mouth and neck portion. Method of molding a metal container according to claim 1 or 2 with a sealing material, characterized in that coating the cut edge of the curl portion.

Images