JP7112648B2

JP7112648B2 - Bottle can manufacturing method

Info

Publication number: JP7112648B2
Application number: JP2020184600A
Authority: JP
Inventors: 孝太朗島田; 一実末
Original assignee: アルテミラ製缶株式会社
Priority date: 2020-11-04
Filing date: 2020-11-04
Publication date: 2022-08-04
Anticipated expiration: 2036-10-20
Also published as: JP2021035696A

Description

本発明は、ボトル缶の製造方法に関するものである。 The present invention relates to a method for manufacturing bottle cans.

このようなボトル缶の製造方法として、例えば特許文献１には、アルミニウム合金等の金属材料から絞り加工、絞りしごき加工またはインパクト成形によって造られ、かつ缶本体がキャップ取付部としてのねじ部を有する口部、テーパー状の肩部、胴部および底部から構成され、キャップを螺合して高い密封性を保持できるねじ付金属缶において、口部のねじ部下端から、半径方向に拡大するテーパー状の肩部上端周囲に、内側に滑らかに湾曲する凹部を形成するとともに、この凹部の下方の連続して外側に滑らかに湾曲する凸部を形成することが記載されている。さらに、この特許文献１では、凹部から連続する滑らかな凸部の湾曲の程度として、垂直方向すなわち缶軸に対して３５°～６０°の傾斜角、具体的には４５°の傾斜角とするのが好ましいと記載されている。 As a method for manufacturing such a bottle can, for example, Patent Document 1 discloses that the can body is manufactured by drawing, drawing and ironing, or impact molding from a metal material such as an aluminum alloy, and the can body has a screw portion as a cap attachment portion. A threaded metal can that consists of a mouth, a tapered shoulder, a body and a bottom, and can maintain a high degree of sealing performance by screwing a cap onto it. A tapered shape that expands radially from the lower end of the threaded part of the mouth. It is described that a recess smoothly curved inward is formed around the upper end of the shoulder of the shoulder, and a protrusion smoothly curved outward is formed continuously below the recess. Furthermore, in Patent Document 1, the degree of curvature of the smooth convex portion continuing from the concave portion is set to a vertical direction, that is, an inclination angle of 35° to 60° with respect to the can axis, specifically an inclination angle of 45°. is described as being preferred.

また、例えば特許文献２には、有底筒状に形成されたアルミニウム合金等の金属製の缶体（有底円筒体）の開口部を縮径してなる口金部の上部外周にねじ部が設けられるとともに、このねじ部よりも下方にキャップ本体下部を巻き締めるための膨出部が形成されたボトル缶の製造方法であって、上記開口部を縮径して口金部を形成した後、その口金部の開口端から所定距離分だけ再び拡径して拡径部を形成し、上記ねじ部は、拡径部が形成された後、ねじを形成する部分を縮径して、その縮径された部分にねじ切り加工することによって形成され、上記膨出部は、ねじ部を形成する際に縮径されずに残った拡径部分によって形成されるボトル缶の製造方法が記載されている。この場合に、上記開口部を縮径した口金部における上記膨出部の下方には、肩部から上端側に延びる首部が形成される。 Further, for example, in Patent Document 2, a screw portion is formed on the outer periphery of the upper portion of a mouthpiece formed by reducing the diameter of the opening of a metal can body (cylindrical body with a bottom) such as an aluminum alloy formed in a cylindrical shape with a bottom. and a bulging portion for winding the lower part of the cap main body below the threaded portion, wherein the diameter of the opening is reduced to form a mouthpiece, The diameter of the mouthpiece is increased again by a predetermined distance from the opening end to form an enlarged diameter portion. A method for manufacturing a bottle-can is described in which the diameter-diametered portion is formed by threading, and the bulging portion is formed by the enlarged-diameter portion that remains without being reduced in diameter when the threaded portion is formed. . In this case, a neck portion extending from the shoulder portion to the upper end side is formed below the bulging portion of the mouthpiece formed by reducing the diameter of the opening.

ここで、上述のような肩部の成形は、内径が徐々に小さくなる円筒状の複数の金型を、内径が大きいものから順に有底円筒体の円筒部の上端側部分に圧入して順次塑性変形させることにより、この円筒部の上端側部分のうちの下端側部分を上端側に向けて段階的に内周側に向かうように傾斜させるとともに、この傾斜した下端側部分よりも内周側を内径が小さくなる円筒状に徐々に縮径させることによって行われる。 Here, the molding of the shoulder portion as described above is performed by press-fitting a plurality of cylindrical molds with gradually decreasing inner diameters into the upper end side portion of the cylindrical portion of the bottomed cylindrical body in order from the larger inner diameter. By plastically deforming, the lower end portion of the upper end portion of the cylindrical portion is gradually inclined toward the inner peripheral side toward the upper end side, and the inclined lower end portion is closer to the inner peripheral side than the inclined lower end portion. is gradually reduced into a cylindrical shape with a smaller inner diameter.

さらに、特許文献２に記載された膨出部の成形は、こうして傾斜させられた肩部の内周側に縮径した円筒状の首部が成形された後に、この首部の内径よりも僅かに大きな外径の下端外周部を有する拡径工具を上端側から首部に挿入して拡径させ、次いでこの拡径した部分の上端側にねじ切り加工することにより、上述のようにねじ切り加工によって縮径されずに残された部分として成形される。 Furthermore, the molding of the bulging portion described in Patent Document 2 is such that after a cylindrical neck portion with a reduced diameter is molded on the inner peripheral side of the inclined shoulder portion, the inner diameter of the neck portion is slightly larger than that of the neck portion. A diameter expanding tool having a lower outer peripheral portion of the outer diameter is inserted into the neck portion from the upper end side to expand the diameter, and then the upper end side of the expanded diameter portion is threaded, so that the diameter is reduced by threading as described above. It is molded as a part left untouched.

特開２００１－２１３４１６号公報JP-A-2001-213416 特許第４９０８５４４号公報Japanese Patent No. 4908544

ところで、近年では、このようなボトル缶を形成する金属材料の省資源化や材料製造の際の省エネルギー化のために缶本体のさらなる薄肉化が強く求められており、例えばアルミニウム合金製のボトル缶の場合には、板厚が０．２３０ｍｍ～０．３００ｍｍ程度のアルミニウム合金よりなる金属板から絞り加工により成形されたカップ状素材に再絞りおよびしごき加工を施して上述のような有底円筒体を成形し、さらに肩部や首部、膨出部を成形するとともにねじ切り加工を行ってボトル缶の缶本体を製造するようなことも要求されている。 By the way, in recent years, there has been a strong demand for further thinning of the can body in order to save resources of metal materials for forming such bottle cans and to save energy in material manufacturing. In the case of , a cup-shaped material formed by drawing from a metal plate made of an aluminum alloy having a thickness of about 0.230 mm to 0.300 mm is subjected to redrawing and ironing to obtain a cylindrical body with a bottom as described above. is required to form the can body of the bottle can by further forming the shoulder, neck, and bulging portion, and performing thread cutting.

しかしながら、このように有底円筒体の薄肉化を図ったボトル缶では有底円筒体の強度は低下することになり、特許文献１に記載されているように凸部の缶軸に対する傾斜角が大きくて首部を成形する際の荷重が大きくなったり、あるいは特許文献２に記載された膨出部を成形する際の荷重が大きくなったりすると、首部の成形の際に有底円筒体に座屈が生じるおそれがある。特に、有底円筒体を成形する際には、肩部や首部、膨出部やキャップ取付部を形成する有底円筒体の円筒部における上端側部分よりも、この円筒部の下端側部分の肉厚を薄くすることがあり、そのような有底円筒体では薄肉とされた胴部の下端側部分での座屈が一層顕著なものとなる。また、膨出部を成形する際の荷重が大きいと膨出部に割れを生じるおそれがある。 However, in the case of a bottle can in which the wall thickness of the bottomed cylindrical body is reduced, the strength of the bottomed cylindrical body is lowered, and as described in Patent Document 1, the inclination angle of the convex portion with respect to the can axis is large. If it is large and the load increases when molding the neck, or if the load increases when molding the bulging portion described in Patent Document 2, it will buckle into a bottomed cylindrical body when molding the neck. may occur. In particular, when molding a bottomed cylindrical body, the lower end side of the cylindrical part forming the shoulder, neck, bulging part, and cap mounting part is more likely than the upper end of the cylindrical part of the bottomed cylindrical body. In some cases, the wall thickness is reduced, and in such a bottomed cylinder, buckling becomes more pronounced at the lower end side portion of the body that is made thinner. In addition, if the load applied during molding of the bulging portion is large, the bulging portion may crack.

本発明は、このような背景の下になされたもので、ボトル缶の缶本体に成形される金属板や有底円筒体の薄肉化を図っても、首部の成形の際に有底円筒体に座屈が生じるのを防ぐことが可能なボトル缶の製造方法を提供することを目的としている。 The present invention has been made under such a background. To provide a method for manufacturing a bottle-can capable of preventing buckling of the bottle-can.

上記課題を解決して、このような目的を達成するために、本発明は、缶本体の底部と一体に成形される外周部に、上記底部から上記缶本体の上端開口部に向けて順に缶軸を中心とした円筒状の胴部と、上端側に向かうに従い縮径する肩部と、この肩部からさらに上端側に向かって延びる首部と、キャップ取付部とが形成されたボトル缶の製造方法であって、金属板から絞り加工により成形されたカップ状素材に再絞りおよびしごき加工と底部成形加工を施して、上記底部と、上記胴部と同外径の円筒部が形成された有底円筒体を成形するＤＩプレス工程と、この有底円筒体の上記円筒部の上端側部分を縮径させることにより、上記肩部と、この肩部から上端側に向かうに従いさらに縮径する上記首部とを成形するボトルネック成形工程と、上記首部の上端部に上記キャップ取付部を成形するキャップ取付部成形工程とを備え、上記ボトルネック成形工程においては、上記肩部の上端側に形成された円筒状部のうち上記肩部との接続部分を除いた部分を直径ｄ０から直径ｄ２まで２回に分けて段階的に縮径することによって上記首部を成形する構成とされており、１回の縮径量が０．５ｍｍ～１．５ｍｍの範囲内とされ、前記ボトルネック成形工程の２回の縮経時に用いられる金型は、缶軸に沿った断面において、缶軸に略平行に延びる円環部と、この前記円環部の上方に位置し、前記円環部よりも径の小さい小径円筒部と、前記円環部と前記小径円筒部の間に設けられ、上方に向かい内周側に傾斜した直線状の傾斜部と、を有しており、前記傾斜部が缶軸に対してなす角度αが１８°～２５°であることを特徴とする。 In order to solve the above-mentioned problems and achieve such objects, the present invention provides a can body which is formed integrally with the bottom portion of the can body, and which has an outer peripheral portion formed integrally with the bottom portion of the can body. Manufacture of a bottle-shaped can having a cylindrical body centered on an axis, a shoulder portion whose diameter is reduced toward the upper end side, a neck portion extending further toward the upper end side from the shoulder portion, and a cap mounting portion. In this method, a cup-shaped material formed by drawing from a metal plate is subjected to redrawing, ironing, and bottom forming processing to form the bottom and a cylindrical portion having the same outer diameter as the body. A DI pressing step for forming a bottom cylindrical body, and a diameter reduction of the upper end side portion of the cylindrical body with a bottom, thereby forming the shoulder portion and the shoulder portion, the diameter of which is further reduced toward the upper end side from the shoulder portion. and a cap mounting portion forming step of forming the cap mounting portion on the upper end portion of the neck portion. The neck portion is formed by stepwise reducing the diameter of the portion of the cylindrical portion excluding the connection portion with the shoulder portion in two steps from diameter d0 to diameter d2. The amount of diameter reduction is within the range of 0.5 mm to 1.5 mm, and the mold used for the two rounds of warp reduction in the bottleneck forming process is substantially parallel to the can axis in the cross section along the can axis. an extending circular ring portion; a small-diameter cylindrical portion located above the circular ring portion and having a diameter smaller than that of the circular ring portion; and a linear inclined portion inclined to the circumferential side, and the angle α formed by the inclined portion with respect to the can axis is 18° to 25°.

このようなボトル缶の製造方法においては、首部における縮径が複数回に分けて段階的に行われるので、個々の段階における縮径量を少なくすることができ、缶軸方向の荷重を小さくすることができる。このため、たとえカップ状素材に成形される金属板の板厚が０．２３０ｍｍ～０．３００ｍｍと薄く、またこのカップ状素材から成形された有底円筒体における円筒部の上端側部分の厚さも０．１８０ｍｍ～０．２２５ｍｍと薄くて、さらに円筒部の下端側部分の厚さはこれよりも薄い場合であっても、首部の成形の際の荷重によって有底円筒体に座屈が生じたり、膨出部の成形の際の荷重によって割れが生じたりするのを防ぐことができる。従って、上記構成のボトル缶の製造方法によれば、このような座屈や割れによるボトル缶の製造歩留まりや製造効率等の低下を招くことなく、ボトル缶の缶本体の薄肉化を図ることができ、さらなる省資源化や省エネルギー化を促すことが可能となる。 In such a bottle-can manufacturing method, since the diameter of the neck portion is reduced stepwise in a plurality of steps, the amount of diameter reduction in each step can be reduced, and the load in the can axial direction can be reduced. be able to. For this reason, even if the thickness of the metal plate formed into the cup-shaped material is as thin as 0.230 mm to 0.300 mm, the thickness of the upper end side portion of the cylindrical portion of the bottomed cylindrical body formed from this cup-shaped material is Even if it is as thin as 0.180 mm to 0.225 mm and the thickness of the lower end of the cylindrical portion is thinner than this, the bottomed cylindrical body may buckle due to the load during molding of the neck. , it is possible to prevent cracks from occurring due to the load during molding of the bulging portion. Therefore, according to the bottle-can manufacturing method having the above-described configuration, it is possible to reduce the thickness of the can body of the bottle-can without causing a decrease in the manufacturing yield and manufacturing efficiency of the bottle-can due to such buckling and cracking. It is possible to promote further resource saving and energy saving.

なお、このようなボトル缶の缶本体に有底円筒体を経て成形される上記金属板は、ＪＩＳＨ４０００におけるＡ３００４またはＡ３１０４のアルミニウム合金であって、２０５℃×２０分ベーキング後の０．２％耐力が２３５Ｎ／ｍｍ^２～２６５Ｎ／ｍｍ^２の範囲であることが望ましい。このベーキング後の耐力が２３５Ｎ／ｍｍ^２を下回ると、上述のような傾斜角や外径拡縮径量としても首部や膨出部の成形の際に有底円筒体の座屈や割れが生じるおそれがあり、また逆にベーキング後の耐力が２６５Ｎ／ｍｍ^２を上回っても、成形に必要な荷重が大きくなって荷重制御が困難となるおそれがある。 The metal plate formed on the can body of such a bottle can through the bottomed cylindrical body is an aluminum alloy of A3004 or A3104 in JIS H 4000, and has a resistance of 0.2 after baking at 205 ° C. for 20 minutes. It is desirable that the % yield strength is in the range of 235 N/mm ² to 265 N/mm ² . If the proof stress after baking is less than 235 N/ ^mm2 , buckling or cracking of the bottomed cylindrical body may occur during molding of the neck and bulging portion even with the above-described inclination angle and outer diameter expansion/reduction amount. Conversely, even if the yield strength after baking exceeds 265 N/mm ² , the load required for molding becomes large, which may make it difficult to control the load.

以上説明したように、本発明によれば、首部を成形する際の有底円筒体の座屈を防止することができ、このような座屈によるボトル缶の製造歩留まりや製造効率等の低下を防ぎつつ、ボトル缶の缶本体のさらなる薄肉化を図って、一層の省資源化や省エネルギー化を促進することが可能となる。 As described above, according to the present invention, it is possible to prevent the bottomed cylinder from buckling when forming the neck portion, thereby preventing the production yield and production efficiency of bottle cans from deteriorating due to such buckling. While preventing this, it is possible to further reduce the thickness of the can body of the bottle can, thereby promoting further resource saving and energy saving.

本発明の一実施形態により製造されるボトル缶の一部破断側面図である。1 is a partially broken side view of a bottle-can manufactured according to one embodiment of the present invention; FIG. 本発明の一実施形態を示すフローチャートである。4 is a flowchart illustrating an embodiment of the invention; 本発明の一実施形態におけるボトルネック成形工程において（ａ）首部が成形される前の有底円筒体を示す断面図、（ｂ）首部を成形する金型（第１の金型）を示す断面図である。(a) Cross-sectional view showing a bottomed cylindrical body before the neck is molded, (b) Cross-section showing a mold (first mold) for molding the neck in the bottleneck molding process in one embodiment of the present invention. It is a diagram. 本発明の一実施形態におけるボトルネック成形工程において（ａ）第１の段階の縮径を行う第１の金型の断面図、（ｂ）図（ａ）に示す第１の金型の首部成形部周辺を示す拡大断面図である。(a) Cross-sectional view of the first mold for reducing the diameter in the first stage, (b) Neck molding of the first mold shown in FIG. 2 is an enlarged cross-sectional view showing the periphery of a part; FIG. 本発明の一実施形態におけるボトルネック成形工程において（ａ）第２の段階の縮径を行う第２の金型の断面図、（ｂ）図（ａ）に示す第２の金型の首部成形部周辺を示す拡大断面図である。(a) Cross-sectional view of the second mold for reducing the diameter of the second stage in the bottleneck molding process in one embodiment of the present invention, (b) neck molding of the second mold shown in FIG. 2 is an enlarged cross-sectional view showing the periphery of a part; FIG. 本発明の一実施形態のボトルネック成形工程により首部が成形された有底円筒体を示す断面図である。FIG. 4 is a cross-sectional view showing a bottomed cylindrical body having a neck formed by a bottleneck forming process according to an embodiment of the present invention; 本発明の一実施形態におけるキャップ取付部成形工程において（ａ）膨出部が成形される前の有底円筒体を示す断面図、（ｂ）膨出部を成形する拡径工具（第１の拡径工具）を示す断面図である。(a) Cross-sectional view showing a bottomed cylindrical body before the bulging portion is formed, (b) Diameter expanding tool for forming the bulging portion (first Fig. 3 is a cross-sectional view showing a diameter expanding tool). 本発明の一実施形態におけるキャップ取付部成形工程において（ａ）第１の段階の拡径を行う第１の拡径工具の断面図、（ｂ）図（ａ）に示す第１の拡径工具の拡径部周辺を示す拡大断面図である。(a) Cross-sectional view of a first diameter expansion tool for performing diameter expansion in the first stage, (b) the first diameter expansion tool shown in FIG. 1 is an enlarged cross-sectional view showing the periphery of an enlarged diameter portion of . 本発明の一実施形態におけるキャップ取付部成形工程において（ａ）第２の段階の拡径を行う第２の拡径工具の断面図、（ｂ）図（ａ）に示す第２の拡径工具の拡径部周辺を示す拡大断面図である。(a) Cross-sectional view of a second diameter-expanding tool for performing diameter-expansion in the second step, (b) the second diameter-expanding tool shown in FIG. 1 is an enlarged cross-sectional view showing the periphery of an enlarged diameter portion of . 本発明の一実施形態のキャップ取付部成形工程により膨出部が成形された有底円筒体を示す断面図である。FIG. 4 is a cross-sectional view showing a bottomed cylindrical body with a bulging portion formed by a cap attachment portion forming step according to an embodiment of the present invention;

図１は、本発明の一実施形態により製造されるボトル缶の缶本体１を示すものであり、図２ないし図１０は、このような缶本体１を製造するための本発明の一実施形態を示すものである。本実施形態によって製造されるボトル缶は、その缶本体１が図１に示すように、底部２と、この底部２と一体に形成されて底部２の外周縁から上端側（図１において上側）に延びる外周部３とを備えており、この上端側に向けて縮径する缶軸Ｃを中心とした概略多段の有底円筒状をなしている。 FIG. 1 shows a can body 1 of a bottle can manufactured according to an embodiment of the present invention, and FIGS. 2 to 10 show an embodiment of the present invention for manufacturing such a can body 1. is shown. As shown in FIG. 1, the can body 1 of the bottle-shaped can manufactured according to the present embodiment has a bottom portion 2, and is integrally formed with the bottom portion 2 so as to extend from the outer peripheral edge of the bottom portion 2 toward the upper end (upper side in FIG. 1). It has a substantially multi-stage bottomed cylindrical shape centered on the can axis C whose diameter is reduced toward the upper end side.

底部２には、缶軸Ｃ方向の内側（缶本体１の上端側）に凹む断面略円弧状のドーム部２ａが中央に形成されるとともに、このドーム部２ａの外周には缶軸Ｃ方向の外側（缶本体１の下端側）に突出する上記環状凸部２ｂが缶軸Ｃ回りの周方向に連続して形成されている。また、外周部３には底部２から缶本体１の上端側の開口部４に向けて順に、缶軸Ｃを中心とした円筒状の胴部５と、上端側に向かうに従い一定の傾斜で漸次縮径する円錐台面状の肩部６と、この肩部６からさらに上端側に向かって延びる筒状の首部７と、下端側に上記膨出部８を備えたやはり筒状で、本実施形態ではねじ切り加工が施されたキャップ取付部９とが形成されている。 A dome portion 2a having a substantially arcuate cross-section is formed in the center of the bottom portion 2 and recessed inward in the direction of the can axis C (upper end side of the can body 1). The annular convex portion 2b that protrudes outward (lower end side of the can body 1) is continuously formed in the circumferential direction around the can axis C. As shown in FIG. In addition, on the outer peripheral portion 3, a cylindrical body portion 5 centering on the can axis C is arranged in order from the bottom portion 2 toward the opening portion 4 on the upper end side of the can body 1, and gradually with a constant inclination toward the upper end side. This embodiment also has a cylindrical shape comprising a truncated conical shoulder portion 6 with a reduced diameter, a cylindrical neck portion 7 extending further from the shoulder portion 6 toward the upper end side, and the bulging portion 8 at the lower end side. , a threaded cap mounting portion 9 is formed.

このようなボトル缶を製造する本発明のボトル缶の製造方法の一実施形態においては、図２のフローチャートに示すように、まずカッピングプレス機によるカッピングプレス工程においてアルミニウム合金等の金属板を円板状に打ち抜いて絞り加工を施すことにより深さの浅いカップ状素材を製造し、このカップ状素材にＤＩプレス機によるＤＩプレス工程において再絞りおよびしごき加工を施して缶軸Ｃ方向に延伸することにより、底部２に上記ドーム部２ａと環状凸部２ｂが形成された有底円筒体（ＤＩ缶）を成形する。 In one embodiment of the bottle can manufacturing method of the present invention for manufacturing such bottle cans, as shown in the flowchart of FIG. A cup-shaped material with a shallow depth is produced by punching into a shape and drawing, and the cup-shaped material is subjected to redrawing and ironing in a DI press process by a DI press machine to stretch in the can axis C direction. Thus, a bottomed cylindrical body (DI can) having the dome portion 2a and the annular convex portion 2b formed on the bottom portion 2 is formed.

ここで、カッピングプレス工程においてカップ状素材に成形される金属板は、本実施形態ではＪＩＳＨ４０００におけるＡ３００４またはＡ３１０４のアルミニウム合金であって、２０５℃×２０分ベーキング後の０．２％耐力が２３５Ｎ／ｍｍ^２～２６５Ｎ／ｍｍ^２の範囲のものが用いられる。また、このカップ状素材から成形される有底円筒体には、外周部に上記缶軸Ｃを中心とした円筒部が形成され、この円筒部の外径は缶本体１の胴部５の外径と略等しい一定外径である。ただし、この円筒部は、その上端側部分の厚さが０．１８０ｍｍ～０．２２５ｍｍの範囲である一方、下端側部分の厚さはこの上端側部分よりも極僅かに薄い。 Here, the metal plate that is formed into the cup-shaped material in the cupping press step is an aluminum alloy of A3004 or A3104 in JIS H 4000 in this embodiment, and has a 0.2% proof stress after baking at 205 ° C. for 20 minutes. Those in the range of 235 N/mm ² to 265 N/mm ² are used. The bottomed cylindrical body molded from this cup-shaped material has a cylindrical portion centered on the can axis C on the outer periphery. It has a constant outer diameter approximately equal to the diameter. However, this cylindrical portion has a thickness in the range of 0.180 mm to 0.225 mm at its upper end portion, while the thickness at its lower end portion is slightly thinner than this upper end portion.

このように成形された有底円筒体は、第１の洗浄工程において洗浄、乾燥され、次いで塗装工程において内外面に塗装が施されて焼き付けられる。そして、塗装が施された有底円筒体は、ボトルネッカーによるボトルネック成形工程において円筒部の上記上端側部分の下端側が金型によって縮径されて上記肩部６と首部７が成形され、次いでキャップ取付部成形工程において首部７の上端側が拡径工具によって拡径されて上記膨出部８が形成されるとともに、この膨出部８よりもさらに上端側に上記ねじ切り加工等が施されて上記キャップ取付部９が形成され、図１に示したようなボトル缶の缶本体１に成形される。 The bottomed cylindrical body formed in this way is washed and dried in the first washing step, and then painted on the inner and outer surfaces and baked in the painting step. Then, in the bottleneck molding process using a bottle necker, the diameter of the lower end side of the upper end side portion of the cylindrical portion of the painted bottomed cylindrical body is reduced by a mold, and the shoulder portion 6 and the neck portion 7 are formed. In the process of forming the cap attachment portion, the upper end side of the neck portion 7 is expanded by a diameter expanding tool to form the bulging portion 8, and the upper end side of the bulging portion 8 is subjected to the above-described thread cutting or the like. A cap attachment portion 9 is formed and molded into the can body 1 of the bottle can as shown in FIG.

こうして成形された缶本体１は、第２の洗浄工程によって洗浄、乾燥された後に、検査工程においてピンホールの有無や外面の異物付着、傷、汚れ、印刷不良等が検査されて飲料工場等に搬送され、飲料等の内容物が充填された後にキャップ取付部９に図示されないキャップが取り付けられて封止され、出荷される。なお、上記各工程の間や各工程中には、有底円筒体の上端縁を切断するトリミングや、必要に応じて底部の環状凸部２ｂの断面形状を再成形するボトムリフォームが行われる。 After being washed and dried in the second washing process, the can body 1 formed in this way is inspected for the presence of pinholes, the adhesion of foreign matter to the outer surface, scratches, stains, printing defects, etc. in the inspection process. After being transported and filled with contents such as beverages, a cap (not shown) is attached to the cap attachment portion 9 and sealed, and then shipped. Note that trimming for cutting the upper edge of the bottomed cylindrical body and, if necessary, bottom reforming for reshaping the cross-sectional shape of the annular projection 2b at the bottom are performed between and during each of the above steps.

ここで、ボトルネッカーによるボトルネック成形工程のうち、上記肩部６の成形は、内径が徐々に小さくなる円筒状の複数の上記金型を、内径が大きいものから順に有底円筒体の円筒部の上端側部分に圧入して塑性変形させることにより、この円筒部の上端側部分のうちの下端側部分を上端側に向けて段階的に内周側に向かうように傾斜させるとともに、この傾斜した下端側部分よりも内周側を内径が小さくなる円筒状に徐々に縮径させることによって行われる。 Here, among the bottle neck molding processes by the bottle necker, the molding of the shoulder portion 6 is performed by forming a plurality of cylindrical molds with gradually decreasing inner diameters into cylindrical portions with bottoms in order from the one with the largest inner diameter. By press-fitting the upper end side portion and plastically deforming it, the lower end side portion of the upper end side portion of the cylindrical portion is inclined toward the upper end side in steps toward the inner peripheral side, and this inclined This is done by gradually reducing the diameter of the inner peripheral side from the lower end side portion to a cylindrical shape with a smaller inner diameter.

図３（ａ）に示すのは、このように上記ボトルネック成形工程において肩部６の成形が終了した有底円筒体１０Ａであり、肩部６の内周部上端側には缶軸Ｃを中心として縮径させられた円筒状部１１Ａが形成されている。そして、図３（ｂ）および図４と図５とに示すのは、この有底円筒体１０Ａの円筒状部１１Ａに首部７を成形する第１、第２の金型２１Ａ、２１Ｂであり、本実施形態のボトルネック成形工程においては、これら第１、第２の金型２１Ａ、２１Ｂをこの順に有底円筒体１０Ａの肩部６から上端側の上記円筒状部１１Ａに挿入することにより、この円筒状部１１Ａを複数回（２回）に分けて段階的に縮径して首部７を成形する。 FIG. 3(a) shows a bottomed cylindrical body 10A in which the shoulder portion 6 has been formed in the above-described bottleneck forming process. A cylindrical portion 11A having a reduced diameter is formed at the center. 3(b), 4 and 5 show first and second molds 21A and 21B for forming the neck portion 7 on the cylindrical portion 11A of the bottomed cylindrical body 10A, In the bottleneck molding process of the present embodiment, by inserting the first and second molds 21A and 21B in this order from the shoulder 6 of the bottomed cylindrical body 10A into the cylindrical portion 11A on the upper end side, The diameter of the cylindrical portion 11A is reduced stepwise in a plurality of times (twice) to form the neck portion 7. As shown in FIG.

これら第１、第２の金型２１Ａ、２１Ｂは缶軸Ｃと同軸となるように配置される略円筒状をなしていて、その内周部には下端側から上端側に向けて順にそれぞれ、缶軸Ｃを中心とする大径円筒部２２Ａ、２２Ｂと、内周側に向かうに従い上端側に向かうように傾斜する凹円錐台面状部２３Ａ、２３Ｂと、首部成形部２４Ａ、２４Ｂと、小径円筒部２５Ａ、２５Ｂとが形成されている。 These first and second molds 21A and 21B are substantially cylindrical and arranged coaxially with the can axis C. Large-diameter cylindrical portions 22A and 22B centered on the can axis C, concave truncated conical surface portions 23A and 23B inclined toward the upper end side toward the inner peripheral side, neck forming portions 24A and 24B, and small-diameter cylinders. Parts 25A and 25B are formed.

大径円筒部２２Ａ、２２Ｂは、有底円筒体１０Ａの円筒部（缶本体１の胴部５）の外周面が嵌合可能な内径を有しており、また凹円錐台面状部２３Ａ、２３Ｂは有底円筒体１０Ａの肩部６よりも缶軸Ｃに対して大きな傾斜で内周側に向かうに従い上端側に向かうように傾斜している。これら大径円筒部２２Ａ、２２Ｂと凹円錐台面状部２３Ａ、２３Ｂの形状、寸法は第１、第２の金型２１Ａ、２１Ｂで同じである。 The large-diameter cylindrical portions 22A and 22B have an inner diameter that allows the outer peripheral surface of the cylindrical portion (body portion 5 of the can body 1) of the bottomed cylindrical body 10A to fit therein, and the concave truncated conical surface portions 23A and 23B. is greater than the shoulder portion 6 of the bottomed cylindrical body 10A with respect to the can axis C, and is inclined toward the upper end side toward the inner peripheral side. The shape and dimensions of these large-diameter cylindrical portions 22A, 22B and concave truncated conical surface portions 23A, 23B are the same in the first and second molds 21A, 21B.

さらに、首部成形部２４Ａ、２４Ｂは下端側から上端側に向けて順に、それぞれ缶軸Ｃに沿った断面において図４（ｂ）および図５（ｂ）に拡大して示すように、凹円錐台面状部２３Ａ、２３Ｂの上端に接する凸円弧等をなす第１凸曲部２４ａと、この第１凸曲部２４ａの上端に接して缶軸Ｃに略平行に上端側に延びる直線状をなす円環部２４ｂと、この円環部２４ｂの上端に接して第１凸曲部２４ａよりも半径の大きな凹円弧等をなす凹曲部２４ｃと、この凹曲部２４ｃの上端に接して上端側に向かうに従い内周側に向かうように缶軸Ｃに対して傾斜した直線状をなす傾斜部２４ｄと、この傾斜部２４ｄの上端と小径円筒部２５Ａ、２５Ｂの下端とに接する凸円弧等をなす第２凸曲部２４ｅとを備えている。 Further, the neck forming portions 24A and 24B are arranged in order from the lower end side to the upper end side, as shown in the enlarged views of FIGS. A first convex curved portion 24a forming a convex circular arc or the like that contacts the upper ends of the shaped portions 23A and 23B, and a straight circle that contacts the upper end of the first convex curved portion 24a and extends substantially parallel to the can axis C toward the upper end side. a ring portion 24b, a concave curved portion 24c forming a concave arc having a radius larger than that of the first convex curved portion 24a in contact with the upper end of the annular portion 24b, and an upper end side in contact with the upper end of the concave curved portion 24c. A linear inclined portion 24d that is inclined with respect to the can axis C so as to move toward the inner peripheral side as it goes, and a convex circular arc or the like that contacts the upper end of the inclined portion 24d and the lower ends of the small-diameter cylindrical portions 25A and 25B. 2 convex curved portion 24e.

ここで、円環部２４ｂの内径（直径）ｄ０と缶軸Ｃ方向の長さは、第１、第２の金型２１Ａ、２１Ｂで互いに等しくされており、円環部２４ｂの内径ｄ０は肩部６の成形が終了した有底円筒体１０Ａの上記円筒状部１１Ａが嵌合可能な大きさとされている。また、凹曲部２４ｃの断面がなす円弧等の半径および缶軸Ｃ方向の長さも、第１、第２の金型２１Ａ、２１Ｂで互いに等しい。従って、このような第１、第２の金型２１Ａ、２１Ｂを、肩部６の成形終了後の有底円筒体１０Ａの上端側から図３に白抜き矢線で示すように缶軸Ｃと同軸に挿入すると、円筒状部１１Ａは上端側から円環部２４ｂの内周面に摺接しつつ凹曲部２４ｃおよび傾斜部２４ｄに沿って縮径させられる。 Here, the inner diameter (diameter) d0 of the annular portion 24b and the length in the direction of the can axis C are made equal to each other in the first and second molds 21A and 21B, and the inner diameter d0 of the annular portion 24b is equal to the shoulder. The cylindrical portion 11A of the bottomed cylindrical body 10A, for which the molding of the portion 6 has been completed, is sized to fit therein. In addition, the radius of the arc formed by the cross section of the concavely curved portion 24c and the length in the direction of the can axis C are also equal between the first and second molds 21A and 21B. Therefore, the first and second molds 21A and 21B are arranged from the upper end side of the bottomed cylindrical body 10A after the molding of the shoulder portion 6 is completed to the can axis C as indicated by the white arrow in FIG. When inserted coaxially, the diameter of the cylindrical portion 11A is reduced along the concave curved portion 24c and the inclined portion 24d while slidingly contacting the inner peripheral surface of the annular portion 24b from the upper end side.

そして、これら第１、第２の金型２１Ａ、２１Ｂにおいては、首部成形部２４Ａ、２４Ｂの傾斜部２４ｄの缶軸Ｃに対する傾斜角αは互いに等しいのに対して、第１の金型２１Ａにおける首部成形部２４Ａの傾斜部２４ｄの缶軸Ｃ方向の長さが、第２の金型２１Ｂにおける首部成形部２４Ｂの傾斜部２４ｄの缶軸Ｃ方向の長さよりも短くなるように形成されている。 In the first and second molds 21A and 21B, the inclination angles α of the inclined portions 24d of the neck molding portions 24A and 24B with respect to the can axis C are equal to each other, whereas in the first mold 21A The length in the can axis C direction of the inclined portion 24d of the neck molding portion 24A is formed to be shorter than the length in the can axis C direction of the inclined portion 24d of the neck molding portion 24B in the second mold 21B. .

これにより、第１の金型２１Ａにおける小径円筒部２５Ａの内径（直径）ｄ１は、有底円筒体１０Ａの円筒状部１１Ａの外径よりも小さく、ただし第２の金型２１Ｂにおける小径円筒部２５Ｂの内径（直径）ｄ２よりは大きくされる。なお、第２凸曲部２４ｅの断面がなす円弧等の半径および缶軸Ｃ方向の長さは、第１、第２の金型２１Ａ、２１Ｂで互いに等しくされている。 As a result, the inner diameter (diameter) d1 of the small-diameter cylindrical portion 25A in the first mold 21A is smaller than the outer diameter of the cylindrical portion 11A of the bottomed cylindrical body 10A, but the small-diameter cylindrical portion in the second mold 21B It is made larger than the inner diameter (diameter) d2 of 25B. The radius of the arc formed by the cross section of the second convex curved portion 24e and the length in the direction of the can axis C are made equal between the first and second molds 21A and 21B.

従って、第１の金型２１Ａにおける凹円錐台面状部２３Ａの上端位置が肩部６の上端位置と缶軸Ｃ方向に一致して第１の金型２１Ａがストロークエンド（下死点）に達したところで、円筒状部１１Ａの上端側部分は第１の金型２１Ａの小径円筒部２５Ａの内径ｄ１と略等しい外径に絞り込まれて一段縮径されるとともに、こうして縮径した円筒状部１１Ａの下端側部分から肩部６にかけては、第１の金型２１Ａの首部成形部２４Ａの断面形状を略転写したような外周面の断面形状を有する上記首部７が形成される。 Therefore, the upper end position of the concave truncated cone surface portion 23A of the first mold 21A coincides with the upper end position of the shoulder portion 6 in the can axis C direction, and the first mold 21A reaches the stroke end (bottom dead center). Then, the upper end side portion of the cylindrical portion 11A is narrowed down to have an outer diameter substantially equal to the inner diameter d1 of the small-diameter cylindrical portion 25A of the first mold 21A, and the diameter of the cylindrical portion 11A thus reduced is reduced. From the lower end side portion to the shoulder portion 6, the neck portion 7 having the cross-sectional shape of the outer peripheral surface which is almost the same as the cross-sectional shape of the neck molding portion 24A of the first mold 21A is formed.

次いで、第１の金型２１Ａを有底円筒体１０Ａから引き抜いて第２の金型２１Ｂを挿入すると、同様に第２の金型２１Ｂにおける凹円錐台面状部２３Ｂの上端位置が肩部６の上端位置と缶軸Ｃ方向に一致して第２の金型２１Ｂがストロークエンド（下死点）に達したところで、円筒状部１１Ａの上端側部分は第２の金型２１Ｂの小径円筒部２５Ｂの内径ｄ２と略等しい外径に絞り込まれてもう一段縮径された円筒状部１１Ｂに成形される。 Next, when the first mold 21A is pulled out from the bottomed cylindrical body 10A and the second mold 21B is inserted, the upper end position of the concave truncated conical surface portion 23B of the second mold 21B is similarly aligned with the shoulder portion 6. When the second mold 21B reaches the stroke end (bottom dead center) in line with the upper end position and the direction of the can axis C, the upper end side portion of the cylindrical portion 11A becomes the small diameter cylindrical portion 25B of the second mold 21B. The cylindrical portion 11B is formed into a cylindrical portion 11B which is narrowed down to an outer diameter substantially equal to the inner diameter d2 of and is further reduced in diameter.

さらに、こうして縮径した円筒状部１１Ｂの下端側部分から肩部６にかけては、円環部２４ｂによって肩部６側に短い円筒状部１１Ａが残されるとともに、この円筒状部１１Ａの上端側には、第２の金型２１Ｂの首部成形部２４Ｂの断面形状を略転写したような外周面の断面形状を有する上記首部縮径部７ａが形成される。これによって、図３（ａ）に示した有底円筒体１０Ａは、図６に示すような首部７を有する有底円筒体１０Ｂに成形される。 Furthermore, from the lower end side portion of the cylindrical portion 11B whose diameter is reduced in this way to the shoulder portion 6, a short cylindrical portion 11A is left on the shoulder portion 6 side by the annular portion 24b, and the upper end side of the cylindrical portion 11A is , the reduced-diameter neck portion 7a having the cross-sectional shape of the outer peripheral surface that is almost the same as the cross-sectional shape of the neck molding portion 24B of the second mold 21B is formed. As a result, the bottomed cylindrical body 10A shown in FIG. 3(a) is formed into a bottomed cylindrical body 10B having the neck portion 7 as shown in FIG.

なお、このように段階的に縮径させられて成形される首部７の１段当たりの缶軸Ｃに対する直径方向の縮径量、すなわち図４に示す第１の金型２１Ａの円環部２４ｂの内径（直径）ｄ０と小径円筒部２５Ａの内径（直径）ｄ１との差ｄ０－ｄ１と、この第１の金型２１Ａの小径円筒部２５Ａの内径（直径）ｄ１と図５に示す第２の金型２１Ｂの小径円筒部２５Ｂの内径（直径）ｄ２との差ｄ１－ｄ２は、それぞれ０．５ｍｍ～１．５ｍｍの範囲とされるのが望ましい。また、これら第１、第２の金型２１Ａ、２１Ｂの首部成形部２４Ａ、２４Ｂにおける傾斜部２４ｄが缶軸Ｃに対してなす傾斜角αは１８°～２５°の範囲とされるのが望ましい。 It should be noted that the amount of diameter reduction in the diameter direction with respect to the can axis C per step of the neck portion 7 molded by being stepwise reduced in this way, that is, the annular portion 24b of the first mold 21A shown in FIG. The difference d0-d1 between the inner diameter (diameter) d0 and the inner diameter (diameter) d1 of the small-diameter cylindrical portion 25A, and the inner diameter (diameter) d1 of the small-diameter cylindrical portion 25A of the first mold 21A and the second shown in FIG. The difference d1-d2 from the inner diameter (diameter) d2 of the small-diameter cylindrical portion 25B of the mold 21B is preferably in the range of 0.5 mm to 1.5 mm. Further, it is desirable that the inclination angle α formed by the inclined portions 24d of the neck molding portions 24A and 24B of the first and second molds 21A and 21B with respect to the can axis C is in the range of 18° to 25°. .

次に、こうして首部７が成形された図６および図７（ａ）に示す有底円筒体１０Ｂの第２の金型２１Ｂによって縮径された円筒状部１１Ｂには、キャップ取付部成形工程において図７（ｂ）および図８と図と９に示すような第１、第２の拡径工具３１Ａ、３１Ｂが挿入されて首部７よりも上端側の部分が拡径され、膨出部８が成形される。 Next, the cylindrical portion 11B whose diameter is reduced by the second mold 21B of the bottomed cylindrical body 10B shown in FIGS. First and second diameter expanding tools 31A and 31B as shown in FIGS. 7B, 8 and 9 are inserted to expand the diameter of the portion on the upper end side of the neck portion 7 so that the bulging portion 8 is molded.

そして、本実施形態では、このキャップ取付部成形工程においても、図８に示すような第１の拡径工具３１Ａと図９に示すような第２の拡径工具３１Ｂとをこの順に上記円筒状部１１Ｂに挿入することによって、この円筒状部１１Ｂを複数回（２回）に分けて段階的に拡径して膨出部８を成形する。 In the present embodiment, the first diameter-enlarging tool 31A as shown in FIG. 8 and the second diameter-enlarging tool 31B as shown in FIG. By inserting into the portion 11B, the diameter of the cylindrical portion 11B is expanded stepwise in a plurality of times (twice) to form the bulging portion 8. As shown in FIG.

これら第１、第２の拡径工具３１Ａ、３１Ｂは、外径が２段の略円筒状をなしていて、やはり缶軸Ｃと同軸に配置され、下端側の小径部３２Ａ、３２Ｂの外径（直径）Ｄ０は互いに等しく、ボトルネック成形工程において縮径した円筒状部１１Ｂの内周に嵌合可能な大きさとされるとともに、上端側の大径部３３Ａ、３３Ｂの外径Ｄ１、Ｄ２は小径部３２Ａ、３２Ｂの外径Ｄ０よりも大きくされている。 These first and second diameter enlarging tools 31A and 31B have a substantially cylindrical shape with a two-step outer diameter, and are also arranged coaxially with the can axis C. (Diameters) D0 are equal to each other and are set to a size that can be fitted to the inner circumference of the cylindrical portion 11B whose diameter has been reduced in the bottleneck molding process. It is made larger than the outer diameter D0 of the small diameter portions 32A and 32B.

また、これら小径部３２Ａ、３２Ｂと大径部３３Ａ、３３Ｂとの間には、缶軸Ｃに沿った断面において図８（ｂ）および図９（ｂ）に拡大して示すように、上端側に向かうに従い外周側に向けて互いに等しい一定の傾斜角βで拡径する拡径部３４Ａ、３４Ｂが形成されている。これらの拡径部３４Ａ、３４Ｂは、小径部３２Ａ、３２Ｂとは断面凹円弧等の凹曲部３４ａを介して接するとともに、大径部３３Ａ、３３Ｂとは凹曲部３４ａよりも半径の大きな断面凸円弧等の凸曲部３４ｂを介して接する断面直線状に形成されている。 Between the small-diameter portions 32A, 32B and the large-diameter portions 33A, 33B, as shown in enlarged view in FIGS. , there are formed diameter-enlarged portions 34A and 34B whose diameters are enlarged at a constant inclination angle β that is equal to each other toward the outer peripheral side. These enlarged diameter portions 34A and 34B are in contact with the small diameter portions 32A and 32B via a concave curved portion 34a such as a concave arc in cross section, and the large diameter portions 33A and 33B have a cross section with a larger radius than the concave curved portion 34a. It is formed to have a linear cross-section that contacts through a convex curved portion 34b such as a convex circular arc.

そして、本実施形態でも、これらの拡径部３４Ａ、３４Ｂの缶軸Ｃ方向の長さが、第２の拡径工具３１Ｂにおいて第１の拡径工具３１Ａよりも長くされており、これにより第２の拡径工具３１Ｂの大径部３３Ｂの外径（直径）Ｄ２は、第１の拡径工具３１Ａの大径部３３Ａの外径（直径）Ｄ１よりも大きくされている。なお、凹曲部３４ａと凸曲部３４ｂの断面がなす円弧の半径と缶軸Ｃ方向の長さは、第１、第２の拡径工具３１Ａ、３１Ｂ同士で互いに等しくされている。 Also in the present embodiment, the length of the enlarged diameter portions 34A and 34B in the can axis C direction is longer in the second diameter expanding tool 31B than in the first diameter expanding tool 31A. The outer diameter (diameter) D2 of the large diameter portion 33B of the second diameter expanding tool 31B is made larger than the outer diameter (diameter) D1 of the large diameter portion 33A of the first diameter expanding tool 31A. The radius of the arc formed by the cross sections of the concavely curved portion 34a and the convexly curved portion 34b and the length in the direction of the can axis C are made equal between the first and second diameter enlarging tools 31A and 31B.

このような第１、第２の拡径工具３１Ａ、３１Ｂのうち、まず第１の拡径工具３１Ａから図７に白抜き矢線で示すように缶軸Ｃと同軸に縮径した円筒状部１１Ｂの内周に小径部３２Ａを摺接しつつ挿入すると、拡径部３４Ａから大径部３３Ａが形成された部分によって円筒状部１１Ｂが上端側から拡径させられる。 Among the first and second diameter-enlarging tools 31A and 31B, the first diameter-enlarging tool 31A has a cylindrical portion whose diameter is reduced coaxially with the can axis C as shown by the white arrow in FIG. When the small-diameter portion 32A is inserted into the inner circumference of the cylindrical portion 11B while slidingly contacting it, the diameter of the cylindrical portion 11B is expanded from the upper end side by the portion where the large-diameter portion 33A is formed from the enlarged-diameter portion 34A.

本実施形態では、こうして挿入された小径部３２Ａの上端が首部７の首部縮径部７ａの上端から缶軸Ｃ方向に僅かに上端側に間隔をあけた位置に配設されたところで第１の拡径工具３１Ａはストロークエンド（下死点）に達する。このとき、首部縮径部７ａの上端側には縮径した円筒状部１１Ｂが首部７に残され、そのさらに上端側に連なるように上端側に向かうに従い拡径する膨出部拡径部８ａが拡径部３４Ａによって成形されて、この膨出部拡径部８ａよりも上端側は大径部３３Ａの外径Ｄ１と略等しい内径の円筒状に成形される。 In this embodiment, when the upper end of the small-diameter portion 32A thus inserted is arranged at a position slightly spaced upward in the direction of the can axis C from the upper end of the reduced-diameter neck portion 7a of the neck portion 7, the first The diameter expanding tool 31A reaches the stroke end (bottom dead center). At this time, a cylindrical portion 11B having a reduced diameter is left in the neck portion 7 at the upper end side of the neck reduced diameter portion 7a. is formed by the enlarged diameter portion 34A, and the upper end side of the expanded enlarged diameter portion 8a is formed into a cylindrical shape having an inner diameter substantially equal to the outer diameter D1 of the large diameter portion 33A.

次に、第１の拡径工具３１Ａを引き抜いて第２の拡径工具３１Ｂを小径部３２Ｂから円筒状部１１Ｂの内周に挿入すると、拡径部３４Ｂから大径部３３Ｂによって円筒状部１１Ｂの上端側がもう一段拡径させられる。そして、こうして挿入された小径部３２Ｂの上端の位置が、第１の拡径工具３１Ａのストロークエンドにおける小径部３２Ａの上端位置と缶軸Ｃ方向に等しい位置まで挿入されたところで、第２の拡径工具３１Ｂはストロークエンド（下死点）に達する。 Next, when the first diameter-enlarging tool 31A is pulled out and the second diameter-enlarging tool 31B is inserted from the small-diameter portion 32B into the inner periphery of the cylindrical portion 11B, the cylindrical portion 11B is expanded from the large-diameter portion 34B to the large-diameter portion 33B. The upper end side of is expanded one more step. Then, when the position of the upper end of the small diameter portion 32B thus inserted is equal to the position of the upper end of the small diameter portion 32A at the stroke end of the first diameter expanding tool 31A in the can axis C direction, the second expansion is performed. The radial tool 31B reaches the stroke end (bottom dead center).

従って、第１の拡径工具３１Ａによって成形された膨出部拡径部８ａはさらに上端側に向かうに従い拡径するように延長されるとともに、この膨出部拡径部８ａよりも上端側は大径部３３Ｂの外径Ｄ２と略等しい内径の円筒状部１１Ｃに成形される。これにより、図６および図７（ａ）に示した有底円筒体１０Ｂは、図１０に示すような有底円筒体１０Ｃに成形される。 Therefore, the bulging portion enlarged diameter portion 8a formed by the first diameter expanding tool 31A is extended so as to increase in diameter further toward the upper end side, and the upper end side of the bulging portion enlarged diameter portion 8a is A cylindrical portion 11C having an inner diameter substantially equal to the outer diameter D2 of the large diameter portion 33B is formed. As a result, the bottomed cylindrical body 10B shown in FIGS. 6 and 7(a) is formed into a bottomed cylindrical body 10C as shown in FIG.

なお、このように段階的に拡径させられて成形される膨出部８の１段当たりの缶軸Ｃに対する直径方向の拡径量、すなわち図８に示す第１の拡径工具３１Ａの小径部３２Ａの外径（直径）Ｄ０と大径部３３Ａの外径（直径）Ｄ１との差Ｄ１－Ｄ０と、この第１の拡径工具３１Ａの大径部３３Ａの外径（直径）Ｄ１と図９に示す第２の拡径工具３１Ｂの大径部３３Ｂの外径（直径）Ｄ２との差Ｄ２－Ｄ１は、それぞれ０．５ｍｍ～１．５ｍｍの範囲とされるのが望ましい。また、これら第１、第２の拡径工具３１Ａ、３１Ｂの拡径部３４Ａ、３４Ｂが缶軸Ｃに対してなす傾斜角βは１５°～３５°の範囲とされるのが望ましい。 It should be noted that the amount of diametrical expansion of the bulging portion 8 that is formed by being stepwise expanded in this way with respect to the can axis C per stage, that is, the small diameter of the first diameter expanding tool 31A shown in FIG. The difference D1-D0 between the outer diameter (diameter) D0 of the portion 32A and the outer diameter (diameter) D1 of the large diameter portion 33A, and the outer diameter (diameter) D1 of the large diameter portion 33A of the first diameter expanding tool 31A. The difference D2-D1 from the outer diameter (diameter) D2 of the large-diameter portion 33B of the second diameter-enlarging tool 31B shown in FIG. 9 is preferably in the range of 0.5 mm to 1.5 mm. Further, it is desirable that the inclination angle β formed by the enlarged diameter portions 34A and 34B of the first and second diameter enlargement tools 31A and 31B with respect to the can axis C is in the range of 15° to 35°.

こうして首部７の上端側に膨出部８が形成されるとともに、この膨出部８の上端側に拡径させられた円筒状部１１Ｃが成形された有底円筒体１０Ｃは、この拡径させられた円筒状部１１Ｃの上端側が上述のようにねじ切り加工等が施されることによりキャップ取付部９が形成されて縮径されるとともに、下端側には縮径されずに膨出部８が残される。さらに、このキャップ取付部９の開口部４にはカール部が形成されるなどして、図１に示したようなボトル缶の缶本体１に成形される。 In this way, the expanded portion 8 is formed on the upper end side of the neck portion 7, and the bottomed cylindrical body 10C formed with the expanded cylindrical portion 11C on the upper end side of the expanded portion 8 is expanded in diameter. The cap attachment portion 9 is formed by subjecting the upper end side of the cylindrical portion 11C to threading or the like as described above, and the diameter thereof is reduced. left. Further, a curled portion is formed in the opening 4 of the cap mounting portion 9, and the can body 1 of the bottle can as shown in FIG. 1 is formed.

このようなボトル缶の製造方法においては、有底円筒体１０Ａ、１０Ｂにおける円筒状部１１Ａ、１１Ｂの首部７の縮径や膨出部８の拡径が複数回に分けて段階的に行われるので、個々の段階における縮径量や拡径量は少なくすることができる。このため、特に首部７が上端側に向かうに従い縮径する首部縮径部７ａや膨出部８が上端側に向かうに従い拡径する膨出部拡径部８ａを有している場合に、有底円筒体１０Ａ、１０Ｂに缶軸Ｃ方向に作用する荷重を軽減することができる。 In such a bottle can manufacturing method, the diameter reduction of the neck portion 7 of the cylindrical portions 11A and 11B of the bottomed cylindrical bodies 10A and 10B and the diameter expansion of the bulging portion 8 are performed stepwise in a plurality of steps. Therefore, the amount of diameter reduction and diameter expansion in each stage can be reduced. For this reason, especially when the neck portion 7 has a neck reduced diameter portion 7a whose diameter is reduced toward the upper end side and a bulging portion enlarged diameter portion 8a whose diameter is increased toward the upper end side, it is effective. The load acting on the bottom cylindrical bodies 10A and 10B in the direction of the can axis C can be reduced.

従って、本実施形態のように、カップ状素材に成形される金属板の板厚が０．２３０ｍｍ～０．３００ｍｍと薄く、またこのカップ状素材からＤＩプレス工程を経て成形された有底円筒体における円筒状部の上端側部分の厚さも０．１８０ｍｍ～０．２２５ｍｍと薄くて、さらにこの円筒部の下端側部分の厚さはこれよりも薄い場合であっても、首部７の成形の際の荷重によって有底円筒体１０Ａ、１０Ｂに座屈が生じるのを防ぐことができる。また、膨出部８を成形する際の荷重によって円筒状部１１Ｃに割れが生じるのも防ぐことができる。このため、上記構成のボトル缶の製造方法によれば、このような座屈や割れによるボトル缶の製造歩留まりや製造効率等の低下を招くことなく、ボトル缶の缶本体１のさらなる薄肉化を図ることができるので、より一層の省資源化や省エネルギー化を促すことが可能となる。 Therefore, as in the present embodiment, the thickness of the metal plate formed into the cup-shaped material is as thin as 0.230 mm to 0.300 mm. The thickness of the upper end side portion of the cylindrical portion is as thin as 0.180 mm to 0.225 mm, and the thickness of the lower end side portion of the cylindrical portion is thinner than this. buckling of the bottomed cylinders 10A and 10B due to the load of . In addition, it is possible to prevent the cylindrical portion 11C from cracking due to the load when the bulging portion 8 is formed. Therefore, according to the bottle-can manufacturing method having the above-described configuration, the can body 1 of the bottle-can can be further thinned without reducing the manufacturing yield and manufacturing efficiency of the bottle-can due to such buckling and cracking. Therefore, it is possible to promote further resource saving and energy saving.

なお、このようなボトル缶の缶本体に有底円筒体を経て成形される上記金属板は、ＪＩＳＨ４０００におけるＡ３００４またはＡ３１０４のアルミニウム合金であって、２０５℃×２０分ベーキング後の０．２％耐力が２３５Ｎ／ｍｍ^２～２６５Ｎ／ｍｍ^２の範囲であることが望ましい。この２０５℃×２０分ベーキング後の０．２％耐力が２３５Ｎ／ｍｍ^２を下回ると、上述のように縮径や拡径を複数回に分けて段階的に行っても首部７や膨出部８の成形の際に有底円筒体１０Ａ、１０Ｂの座屈や割れが生じるおそれがあり、また逆に２６５Ｎ／ｍｍ^２を上回っても、成形に必要な荷重が大きくなって荷重制御が困難となり、やはり座屈や割れを生じ易くなるおそれがある。 The metal plate formed on the can body of such a bottle can through the bottomed cylindrical body is an aluminum alloy of A3004 or A3104 in JIS H 4000, and has a resistance of 0.2 after baking at 205 ° C. for 20 minutes. It is desirable that the % yield strength is in the range of 235 N/mm ² to 265 N/mm ² . If the 0.2% yield strength after baking at 205°C for 20 minutes is less than 235 N/ ^mm2 , the neck 7 and bulging portion will not be Buckling or cracking of the bottomed cylindrical bodies 10A and 10B may occur during the molding of 8, and conversely, even if it exceeds 265 N/mm ² , the load required for molding increases, making it difficult to control the load. , there is a possibility that buckling and cracking may easily occur.

また、本実施形態では、首部７の縮径および膨出部８の拡径をそれぞれ２回に分けて段階的に行っているが、３回以上の回数で段階的に行ってもよい。ただし、これら縮径や拡径を行うときの回数が多くなりすぎると製造効率が損なわれるので、段階的に行う場合の回数は３回以下とされるのが望ましい。 Further, in the present embodiment, the diameter reduction of the neck portion 7 and the diameter expansion of the bulging portion 8 are performed stepwise in two steps, respectively, but may be stepwise performed three or more times. However, if the number of times of diameter reduction and diameter expansion is excessively increased, the manufacturing efficiency is impaired.

さらに、各段階の縮径量や拡径量の差が大きすぎると、大きな縮径量または拡径量の成形の際の座屈を確実に防ぐことができなくなるおそれがあるので、これら各段階の縮径量や拡径量は上述した範囲内にあるのが望ましく、互いに等しい縮径量や拡径量であるのがより望ましい。なお、首部７の縮径量や膨出部８の拡径量によっては、縮径と拡径の一方だけを複数回に分けて段階的に行い、他方は１回の縮径や拡径だけで成形するようにしてもよい。 Furthermore, if the difference in diameter reduction amount or diameter expansion amount in each stage is too large, it may not be possible to reliably prevent buckling during molding with a large diameter reduction amount or diameter expansion amount. It is desirable that the amount of diameter reduction and the amount of diameter expansion be within the range described above, and more preferably that the amount of diameter reduction and the amount of diameter expansion be equal to each other. Depending on the amount of diameter reduction of the neck portion 7 and the amount of diameter expansion of the bulging portion 8, only one of the diameter reduction and the diameter expansion is performed stepwise in a plurality of times, and the other diameter reduction or diameter expansion is performed only once. You may make it shape|mold with.

次に、本発明の実施例を挙げて、本発明の効果について説明する。本実施例では、ＪＩＳＨ４０００におけるＡ３１０４のアルミニウム合金であって、２０５℃×２０分ベーキング後の０．２％耐力が２５４．８Ｎ／ｍｍ^２、板厚０．３００ｍｍの金属板からカッピングプレス工程においてカップ状素材を成形し、さらにＤＩプレス工程において底部と円筒部とを有する有底円筒体を成形した。 Next, the effects of the present invention will be described with reference to examples of the present invention. In this example, a metal plate of aluminum alloy A3104 in JIS H 4000 having a 0.2% yield strength of 254.8 N/mm after baking at 205°C for ²⁰ minutes and a thickness of 0.300 mm was subjected to a cupping press process. A cup-shaped material was formed in , and a cylinder with a bottom having a bottom and a cylindrical portion was formed in a DI press step.

次いで、この有底円筒体にボトルネック成形工程において肩部６を形成して図３（ａ）に示すような円筒状部１１Ａを有する有底円筒体１０Ａを成形した後、この円筒状部１１Ａに第１、第２の２つの金型２１Ａ、２１Ｂによって２回の縮径を行い、図６に示す有底円筒体１０Ｂのような首部縮径部７ａを有する首部７を成形した。 Then, shoulder portions 6 are formed in this bottomed cylindrical body in a bottleneck forming step to form a bottomed cylindrical body 10A having a cylindrical portion 11A as shown in FIG. 3(a). Then, the diameter was reduced twice by the first and second molds 21A and 21B to form a neck portion 7 having a reduced neck portion 7a like the bottomed cylindrical body 10B shown in FIG.

なお、これら第１、第２の金型２１Ａ、２１Ｂにおいて、首部成形部２４Ａ、２４Ｂにおける傾斜部２４ｄの缶軸Ｃに対する傾斜角αはともに２０°であり、第１の金型２１Ａの円環部２４ｂの内径（直径）ｄ０と小径円筒部２５Ａの内径（直径）ｄ１との差ｄ０－ｄ１は１．１ｍｍ、この第１の金型２１Ａの小径円筒部２５Ａの内径（直径）ｄ１との第２の金型２１Ｂの小径円筒部２５Ｂの内径（直径）ｄ２の差ｄ１－ｄ２も同じく１．１ｍｍであって、円筒状部１１Ａの外径（直径）の総縮径量は２．２ｍｍであった。これを実施例１とする。 In these first and second molds 21A and 21B, the inclination angle α of the inclined portion 24d of the neck molding portions 24A and 24B with respect to the can axis C is both 20°. The difference d0-d1 between the inner diameter (diameter) d0 of the portion 24b and the inner diameter (diameter) d1 of the small-diameter cylindrical portion 25A is 1.1 mm. The difference d1-d2 of the inner diameter (diameter) d2 of the small-diameter cylindrical portion 25B of the second mold 21B is also 1.1 mm, and the total diameter reduction amount of the outer diameter (diameter) of the cylindrical portion 11A is 2.2 mm. Met. This is referred to as Example 1.

また、この実施例１に対する比較例として、円環部２４ｂの内径（直径）ｄ０と小径円筒部２５Ｂの内径（直径）ｄ２との差ｄ０－ｄ２が上記総縮径量と等しい２．２ｍｍとなる第２の金型２１Ｂを単一で用いて、１回の縮径により有底円筒体１０Ａの円筒状部１１Ａの外径（直径）を２．２ｍｍ縮径して首部７を成形した。これを比較例１とする。そして、これら実施例１と比較例１とによる首部７の成形の際の成形荷重を測定するとともに、１００個の有底円筒体１０Ａに首部７を成形したときに座屈が生じた有底円筒体１０Ａの数を確認した。この結果を、縮径量とともに表１に示す。 Further, as a comparative example with respect to Example 1, the difference d0-d2 between the inner diameter (diameter) d0 of the annular portion 24b and the inner diameter (diameter) d2 of the small-diameter cylindrical portion 25B is 2.2 mm, which is equal to the total diameter reduction amount. Using a single second mold 21B, the outer diameter (diameter) of the cylindrical portion 11A of the cylindrical body 10A with a bottom was reduced by 2.2 mm to mold the neck portion 7 once. This is referred to as Comparative Example 1. Then, the molding load during molding of the neck portion 7 according to Example 1 and Comparative Example 1 was measured, and the bottomed cylinders in which buckling occurred when the neck portions 7 were formed on 100 bottomed cylindrical bodies 10A were measured. The number of bodies 10A was confirmed. The results are shown in Table 1 together with the amount of diameter reduction.

なお、ＤＩプレス工程において成形された有底円筒体は、円筒部の直径（缶本体１の胴部５の直径）が約６６ｍｍであり、この円筒部の上端側部分の厚さは実施例１および比較例１ともに０．２００ｍｍであった。また、この有底円筒体にボトルネック成形工程において肩部６が成形された図３（ａ）に示した有底円筒体１０Ａは、底部２の下端から円筒部の上端までの缶軸Ｃ方向の高さが１３７ｍｍ、底部２の下端から肩部６の上端までの缶軸Ｃ方向の高さが１０５ｍｍ、肩部６の上端側に成形された縮径した円筒状部１１Ａの外径（直径）は３８ｍｍであった。 The diameter of the cylindrical portion (the diameter of the body portion 5 of the can body 1) of the bottomed cylindrical body formed in the DI pressing process is about 66 mm, and the thickness of the upper end portion of the cylindrical portion is about 66 mm. and Comparative Example 1 were both 0.200 mm. The bottomed cylindrical body 10A shown in FIG. 3(a), in which the shoulder portion 6 is formed in the bottle neck forming process, is formed from the bottom end of the bottom portion 2 to the upper end of the cylindrical portion in the can axis C direction. is 137 mm, the height in the can axis C direction from the lower end of the bottom portion 2 to the upper end of the shoulder portion 6 is 105 mm, and the outer diameter (diameter ) was 38 mm.

この表１の結果より、首部７の成形を１回で行う比較例１では、成形荷重が２１００Ｎと大きく、これに伴い１００個の有底円筒体１０Ａ中で座屈する有底円筒体１０Ａが１５個と多く、ボトルネッカーによって首部７を成形する際に頻繁に装置の停止を余儀なくされることが分かる。これに対して、首部７の成形を２回に分けて行う実施例１では、１回当たりの成形荷重は比較例１よりも大幅に小さくて有底円筒体１０Ａへの負荷が小さく、座屈する有底円筒体１０Ａも０個であったことから、ボトルネッカーによる首部７の成形を円滑かつ効率的に行うことができるとともに、製造歩留まりの向上を図ることが可能となる。 From the results of Table 1, in Comparative Example 1 in which the neck portion 7 is formed in one step, the forming load is as large as 2100 N, and accordingly, 15 bottomed cylindrical bodies 10A among 100 bottomed cylindrical bodies 10A buckle. It can be seen that the machine must be stopped frequently when forming the neck portion 7 due to bottle neckers. On the other hand, in Example 1, in which the neck portion 7 is formed in two steps, the forming load per time is significantly smaller than that in Comparative Example 1, and the load on the bottomed cylindrical body 10A is small, causing buckling. Since the number of bottomed cylinders 10A is also zero, the neck portion 7 can be smoothly and efficiently formed by a bottle necker, and the manufacturing yield can be improved.

次に、こうして首部７が成形された図６に示すような有底円筒体１０Ｂの円筒状部１１Ｂに、この首部７から上端側の部分を複数回に分けて段階的に拡径することによって膨出部８を成形した。このとき、まず実施例２として、上記実施形態と同様に第１、第２の２つの拡径工具３１Ａ、３１Ｂによって２回の拡径を行い、さらに実施例３として、第１ないし第３の３つの拡径工具によって３回の拡径を行い、実施例２と等しい拡径量で拡径する膨出部８を成形した。 Next, the cylindrical portion 11B of the bottomed cylindrical body 10B having the neck portion 7 molded in this manner as shown in FIG. A bulging portion 8 was molded. At this time, first, as Example 2, the diameter is expanded twice by the first and second two diameter expansion tools 31A and 31B in the same manner as in the above-described embodiment. The diameter was expanded three times using three diameter-expanding tools, and a bulging portion 8 whose diameter was expanded by the same diameter expansion amount as in Example 2 was formed.

なお、これら第１、第２の拡径工具３１Ａ、３１Ｂおよび第３の拡径工具における拡径部３４Ａ、３４Ｂが缶軸Ｃに対してなす傾斜角βは２０°であり、実施例２における第１の拡径工具３１Ａの小径部３２Ａの外径（直径）Ｄ０と大径部３３Ａの外径（直径）Ｄ１との差Ｄ１－Ｄ０と、第１の拡径工具３１Ａの大径部３３Ａの外径（直径）Ｄ１と第２の拡径工具３１Ｂの大径部３３Ｂの外径（直径）Ｄ２との差Ｄ２－Ｄ１は、それぞれ１．０ｍｍであって、総拡径量は２．０ｍｍであった。 The inclination angle β formed by the diameter-enlarging portions 34A and 34B of the first and second diameter-enlarging tools 31A, 31B and the third diameter-enlarging tool with respect to the can axis C is 20°. The difference D1-D0 between the outer diameter (diameter) D0 of the small diameter portion 32A of the first diameter expanding tool 31A and the outer diameter (diameter) D1 of the large diameter portion 33A, and the large diameter portion 33A of the first diameter expanding tool 31A The difference D2-D1 between the outer diameter (diameter) D1 of the second diameter expanding tool 31B and the outer diameter (diameter) D2 of the large diameter portion 33B of the second diameter expanding tool 31B is 1.0 mm, and the total diameter expansion amount is 2.0 mm. was 0 mm.

また、実施例３における第１の拡径工具３１Ａの小径部３２Ａの外径（直径）Ｄ０と大径部３３Ａの外径（直径）Ｄ１との差Ｄ１－Ｄ０と、第１の拡径工具３１Ａの大径部３３Ａの外径（直径）Ｄ１と第２の拡径工具３１Ｂの大径部３３Ｂの外径（直径）Ｄ２との差Ｄ２－Ｄ１はそれぞれ０．７ｍｍであり、第３の拡径工具の大径部の外径（直径）と第２の拡径工具３１Ｂの大径部３３Ｂの外径（直径）Ｄ２との差は０．６ｍｍで、総拡径量を２．０ｍｍとした。 Further, the difference D1-D0 between the outer diameter (diameter) D0 of the small diameter portion 32A and the outer diameter (diameter) D1 of the large diameter portion 33A of the first diameter expanding tool 31A in Example 3, and the first diameter expanding tool The difference D2-D1 between the outer diameter (diameter) D1 of the large diameter portion 33A of 31A and the outer diameter (diameter) D2 of the large diameter portion 33B of the second diameter expanding tool 31B is 0.7 mm. The difference between the outer diameter (diameter) of the large diameter portion of the diameter expanding tool and the outer diameter (diameter) D2 of the large diameter portion 33B of the second diameter expanding tool 31B is 0.6 mm, and the total diameter expansion amount is 2.0 mm. and

さらに、これら実施例２、３に対する比較例２として、やはり実施例２、３と等しい総拡径量の膨出部８の成形を、実施例２の第２の拡径工具３１Ｂと同じ単一の拡径工具による１回の拡径によって行い、その際の成形荷重を測定するとともに、１００個の有底円筒体１０Ｂに膨出部８を成形したときに割れが生じた有底円筒体１０Ｂの数を確認した。この結果を、個々の拡径工具による拡径量とともに表２に示す。 Furthermore, as a comparative example 2 for these examples 2 and 3, the bulging portion 8 having the same total diameter expansion amount as that of the examples 2 and 3 is formed by the same single tool as the second diameter expanding tool 31B of the example 2. The diameter is expanded once by the diameter expansion tool, and the forming load at that time is measured, and when the bulging portion 8 is formed on 100 bottomed cylindrical bodies 10B, cracks occur in the bottomed cylindrical bodies 10B. confirmed the number of The results are shown in Table 2 together with the amount of diameter expansion by each diameter expansion tool.

従って、この表２の結果からも、膨出部８の成形を１回で行う比較例２では、成形荷重が１８００Ｎと大きく、これに伴い１００個の有底円筒体１０Ｂ中で割れが生じた有底円筒体１０Ｂも１３個と多くて、ボトルネッカーによる成形する際に頻繁な停止を余儀なくされる。これに対して、膨出部８の成形を複数回に分けて段階的に行う実施例２、３では、１回当たりの成形荷重は比較例２よりも小さく、特に３回で行う実施例３では成形荷重が大幅に小さく、またいずれも割れが生じた有底円筒体１０Ｂが０個であったことから、ボトルネッカーによる製造効率や製造歩留まりの向上を図ることが可能となる。 Therefore, also from the results of Table 2, in Comparative Example 2 in which the bulging portion 8 was formed in one step, the forming load was as large as 1800 N, and cracks occurred in the 100 bottomed cylindrical bodies 10B. There are also 13 bottomed cylinders 10B, which is a large number, and frequent stops are unavoidable during molding by the bottle necker. On the other hand, in Examples 2 and 3, in which the forming of the bulging portion 8 is divided into a plurality of steps in a stepwise manner, the forming load per step is smaller than in Comparative Example 2, particularly in Example 3, in which the forming is performed three times. Since the forming load was significantly small and the number of cracked bottomed cylindrical bodies 10B was zero in all cases, it is possible to improve the manufacturing efficiency and manufacturing yield by the bottlenecker.

１缶本体
２底部
３外周部
４開口部
５胴部
６肩部
７首部
７ａ首部縮径部
８膨出部
８ａ膨出部拡径部
９キャップ取付部
１０Ａ～１０Ｃ有底円筒体
１１Ａ～１１Ｃ円筒状部
２１Ａ第１の金型
２１Ｂ第２の金型
２４Ａ、２４Ｂ首部成形部
２４ｄ傾斜部
３１Ａ第１の拡径工具
３１Ｂ第２の拡径工具
３４Ａ、３４Ｂ拡径部
Ｃ缶軸
α 首部縮径部７ａの缶軸Ｃに対する傾斜角
β 膨出部拡径部８ａの缶軸Ｃに対する傾斜角
ｄ０円環部２４ｂの内径（縮径前の円筒状部１１Ａの直径）
ｄ１第１の金型２１Ａにおける小径円筒部２５Ａの内径（第１の金型２１Ａによって縮径した円筒状部１１Ａの直径）
ｄ２第２の金型２１Ｂにおける小径円筒部２５Ｂの内径（第２の金型２１Ｂによって縮径した円筒状部１１Ａの直径）
Ｄ０第１、第２の拡径工具３１Ａ、３１Ｂの小径部３２Ａ、３２Ｂの外径（拡径前の円筒状部１１Ｂの内径）
Ｄ１第１の拡径工具３１Ａの大径部３３Ａの外径（第１の拡径工具３１Ａによって拡径した円筒状部１１Ｂの内径）
Ｄ２第２の拡径工具３１Ｂの大径部３３Ｂの外径（第２の拡径工具３１Ｂによって拡径した円筒状部１１Ｂの内径） 1 can body 2 bottom 3 outer periphery 4 opening 5 body 6 shoulder 7 neck 7a neck reduced diameter portion 8 bulging portion 8a bulging portion enlarged diameter portion 9 cap mounting portion 10A to 10C bottomed cylindrical body 11A to 11C cylinder Shaped part 21A First mold 21B Second mold 24A, 24B Neck forming part 24d Inclined part 31A First diameter expanding tool 31B Second diameter expanding tool 34A, 34B Diameter expanding part C Can shaft α Neck diameter reduction Inclination angle of portion 7a with respect to can axis C β Inclination angle of bulging portion enlarged diameter portion 8a with respect to can axis C d0 Inner diameter of annular portion 24b (diameter of cylindrical portion 11A before diameter reduction)
d1 inner diameter of small-diameter cylindrical portion 25A in first mold 21A (diameter of cylindrical portion 11A reduced in diameter by first mold 21A)
d2 inner diameter of small-diameter cylindrical portion 25B in second mold 21B (diameter of cylindrical portion 11A reduced in diameter by second mold 21B)
D0 Outer diameter of small-diameter portions 32A and 32B of first and second diameter-enlarging tools 31A and 31B (inner diameter of cylindrical portion 11B before diameter-enlarging)
D1 Outer diameter of large-diameter portion 33A of first diameter-enlarging tool 31A (inner diameter of cylindrical portion 11B diameter-enlarged by first diameter-enlarging tool 31A)
D2 Outer diameter of large-diameter portion 33B of second diameter-enlarging tool 31B (inner diameter of cylindrical portion 11B diameter-enlarged by second diameter-enlarging tool 31B)

Claims

The outer peripheral portion integrally formed with the bottom of the can body has a cylindrical body centered on the can axis in order from the bottom toward the upper end opening of the can body, and a shoulder whose diameter decreases toward the upper end. A method for manufacturing a bottle-can having a portion, a neck portion extending from the shoulder portion toward the upper end, and a cap mounting portion, the method comprising:
A cup-shaped material formed by drawing from a metal plate is subjected to re-drawing, ironing, and bottom forming processing to form a bottomed cylindrical body having the bottom and a cylindrical portion with the same outer diameter as the body. a DI press process to
a bottleneck forming step of forming the shoulder portion and the neck portion whose diameter is further reduced toward the upper end side from the shoulder portion by reducing the diameter of the upper end side portion of the cylindrical portion of the bottomed cylindrical body;
a cap mounting portion forming step for forming the cap mounting portion on the upper end portion of the neck;
In the bottleneck molding step, the portion of the cylindrical portion formed on the upper end side of the shoulder portion, excluding the connection portion with the shoulder portion, is stepwise contracted in two steps from diameter d0 to diameter d2. The neck portion is formed by diameter reduction, and the amount of diameter reduction at one time is within the range of 0.5 mm to 1.5 mm,
The mold used for the two rounds of warping in the bottleneck forming step includes, in a cross section along the can axis, an annular portion extending substantially parallel to the can axis, and positioned above the annular portion. a small-diameter cylindrical portion having a diameter smaller than that of the annular portion; and a linear inclined portion provided between the annular portion and the small-diameter cylindrical portion and inclined upward toward the inner circumference, A method for manufacturing bottle cans, wherein the angle α formed by the inclined portion with respect to the can axis is 18° to 25°.

2. The manufacture of bottle cans according to claim 1, wherein the bottomed cylindrical body molded from the cup-shaped material has a thickness of 0.180 mm to 0.225 mm at the upper end side portion of the cylindrical portion. Method.

3. The method for manufacturing bottle cans according to claim 1, wherein the metal plate formed into the cup-shaped material has a plate thickness of 0.230 mm to 0.300 mm.

The metal plate is an aluminum alloy of A3004 or A3104 according to JIS H 4000, and has a 0.2% yield strength of 235 N/mm ² to 265 N/mm ² after baking at 205° C. for 20 minutes. The manufacturing method of the bottle can according to any one of claims 1 to 3.