JP2004074169A

JP2004074169A - Screw forming device, bottle can, and bottle

Info

Publication number: JP2004074169A
Application number: JP2002233918A
Authority: JP
Inventors: Tatsuya Hanabusa; 花房　達也; Ryuichi Ito; 伊藤　隆一; Masahiro Hosoi; 細井　正宏
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2002-08-09
Filing date: 2002-08-09
Publication date: 2004-03-11
Anticipated expiration: 2022-08-09
Also published as: JP4137552B2

Abstract

<P>PROBLEM TO BE SOLVED: To reliably form all screw parts so as to have a nearly same height (depth). <P>SOLUTION: In a screw forming part 21, threads of a second stage screw forming part 21b out of first to third screw forming parts 21a-21c of a thread area are formed higher than those of the first stage screw forming part 21a and the third stage screw forming part 21c. In other words, only the threads of the second stage screw forming part 21b out of those of the first stage screw forming part 21a, the second stage screw forming part 21b, and the third stage screw forming part 21c are formed slightly higher than those of the first stage screw forming part 21a and the third stage screw forming part 21c. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は、ボトル缶体の口金部にキャップを被着するためにねじ部を形成するねじ成形装置と、そのねじ部を有するボトル缶体と、そのボトル缶体の口金部にキャップが被着されてなるボトルとに関する。
【０００２】
【従来の技術】
金属製の缶体を絞り加工して得られる、いわゆるボトル缶体は、有底筒上に形成されたボトル缶体の開口部に口金部を形成すると、その口金部の外周にキャップを被着するためのねじ部が形成される。
【０００３】
このようなねじ部を有するボトル缶体を制作するには、予め有底円筒状のボトル缶体が形成されると、そのボトル缶体の開口部を、図９（ａ）に示すように、一旦縮径して口金部２を形成し、次いで、その口金部２の開口端から所定距離分だけ拡径して同図（ｂ）に示すように拡径部２′を形成した後、さらにねじ成形装置によって開口端から一定の距離に同図（ｃ）のようにねじ部３を形成する。その場合、口金部２にねじ部３を形成したとき、ねじ部３の形成されていない拡径部分を残すことにより、膨出部４が形成される。
【０００４】
従来のねじ成形装置は、図示していないが、口金部２の内周面に当接する中子と、口金部２の外周面に当接する外子とが互いに口金部２を挟み込みながらボトル缶体１の軸心周りに回転することで、口金部２の外周にねじ部３を形成するようになっている。この場合、口金部２に形成されるねじ部３の巻き数としては、図１０に示すようにおよそ１．７巻程度となっている。なお、ねじ部３が形成されたボトル缶体１は、その後種々の工程を経て内部に内容物が入れられた後、図１０に示すキャップ５が被着されて密閉される。
【０００５】
【発明が解決しようとする課題】
上述したように、従来のねじ成形装置は、ボトル缶体１の口金部２の内周面に当接する中子と、口金部２の外周面に当接する外子が互いに挟み込みながらボトル缶体の軸心周りに回転することで、拡径された口金部２に１．７の巻数からなるねじ部３を形成している。
【０００６】
ところが、ねじ部の巻数が１．７巻程度であると、図１０に示すように、口金部２の周面においてねじ部３が二本ある部分と、ねじ部３が一本しかない部分とが生じ、その本数の差に伴う問題があった。即ち、上記巻数であると、ボトル缶体１にキャップ５を被着し、ボトル缶体１内が陽圧とした場合、キャップ５を押し上げる圧力が加わることから、キャップ５が上方にずれてしまう。そのため、キャップ５がボトル缶体１に対して偏ってしまうので、キャップ５の開口端側のスコア６と６との間に設けられたブリッジ７が引張られて破断してしまい、いわゆるブリッジ切れが起こる不具合があった。
【０００７】
上記不具合を解消するため、図１１に示すように、ねじ部３の巻数を増やし、２．２巻にすることが試みられている。このようにボトル缶体１の口金部２に２．２巻数のねじ部３を形成すると、ねじ部３のねじ始まり部分からねじ終わり部分との間では、ねじ部３が、一段目ねじ３ａと二段目ねじ３ｂと三段目ねじ３ｃとのように三段となるねじ山領域Ｌが存在することとなる。
【０００８】
しかしながら、ボトル缶体１に２．２巻のねじ部３を形成すると、三段となるねじ山領域Ｌにおいては、その成形時に、ボトル缶体１の一段目ねじ３ａと三段目ねじ３ｃとによって二段目ねじ３ｂが引っ張られてしまう。つまり、従来のねじ成形装置において、口金部２に２．２巻のねじ部３を形成すると、図１２に示すように、一段目ねじ３ａを形成する口金部２の材料により、二段目ねじ３ｂを形成する材料が矢印ａのように一段目ねじ３ａ方向に引張られてしまうと共に、三段目ねじ３ｃを形成する口金部２の材料により、二段目ねじ３ｂを形成する材料が矢印ｂのような三段目ねじ３ｃ方向に引張られてしまう。
【０００９】
そのため、二段目ねじ３ｂの山（深さ）が鎖線に示す設定された箇所より浅いい寸法となり、実線に示すように若干凹んで形成されてしまう結果、二段目ねじ３ｂが一段目、三段目ねじ３ａ、３ｃより小さな寸法となる問題があった。
このように、二段目ねじ３ｂが一段目、三段目ねじ３ａ、３ｃより小さい寸法に形成されると、均等なキャップ５の封止力を得ることができず、そのため、ボトル缶体１に、飲料水を充填し、かつキャップ５を被着した場合、飲料水の内圧が上昇すると、キャップ５がずれるという不具合があった。
【００１０】
この発明は、このような事情を考慮してなされたもので、その目的は、ねじ山領域が三段となるようにねじ部の巻数を増やしても、ねじ部を長さに沿い確実に略同様の高さ（深さ）に形成することができ、内容物の圧力でキャップがボトル缶体からずれることのないねじ成形装置を提供することにあり、他の目的は、そのねじ成形装置によって形成されたねじ部を有するボトル缶体及びボトルを提供することにある。
【００１１】
【課題を解決するための手段】
上記目的を達成するために、この発明は以下の手段を提案している。
請求項１に係る発明は、ボトル缶体の口金部の内周面に当接し、かつ外周に前記口金部に形成すべきねじ部を設けるためのねじ形成部を有する中子と、前記口金部の外周面に当接し、かつ外周に中子の前記ねじ形成部と対応する形状のねじ形成部を有する外子とを備え、中子と外子が前記口金部を挟み込みながらボトル缶体の軸心周りに回転し、前記口金部の外周面に対して、一段目ねじと二段目ねじと三段目ねじとの三段からなるねじ山領域を有する巻数のねじ部を形成するねじ成形装置であって、中子の前記ねじ形成部は、口金部の前記ねじ山領域内の二段目ねじを形成する二段目ねじ形成部を、これと隣接する一段目ねじ形成部と三段目ねじ形成部との深さより深くして形成していることを特徴とする。
【００１２】
この発明に係るねじ成形装置によれば、中子に設けられているねじ形成部において、口金部のねじ山領域内の二段目ねじを形成する二段目ねじ形成部を、これと隣接する一段目ねじ形成部と三段目ねじ形成部との深さより深くして形成しているので、中子と外子で口金部の外周面にねじ部を形成すると、ねじ山領域内の二段目ねじが一段目ねじと三段目ねじとに引張られても、二段目ねじの高さが一段目ねじと三段目ねじとの高さと略同様の寸法にすることができ、口金部に設けられたねじ部のそれぞれの段のねじの高さを略同様の高さにすることができる。
【００１３】
請求項２に係る発明は、ボトル缶体の口金部の内周面に当接し、かつ外周に前記口金部に形成すべきねじ部を設けるためのねじ形成部を有する中子と、前記口金部の外周面に当接し、かつ外周に中子の前記ねじ形成部と対応する形状のねじ形成部を有する外子とを備え、中子と外子が前記口金部を挟み込みながらボトル缶体の軸心周りに回転し、前記口金部の外周面に対して、一段目ねじと二段目ねじと三段目ねじとの三段からなるねじ山領域を有する巻数のねじ部を形成するねじ成形装置であって、外子の前記ねじ形成部は、口金部の前記ねじ山領域内の二段目ねじを形成する二段目ねじ形成部を、これと隣接する一段目ねじ形成部と三段目ねじ形成部との深さより深くして形成していることを特徴とする。
【００１４】
この発明に係るねじ成形装置によれば、外子に設けられているねじ形成部において、口金部のねじ山領域内の二段目ねじを形成する二段目ねじ形成部を、これと隣接する一段目ねじ形成部と三段目ねじ形成部との深さより深くして形成しているので、中子と外子で口金部の外周面にねじ部を形成すると、ねじ山領域内の二段目ねじが一段目ねじと三段目ねじとに引張られても、二段目ねじの高さが一段目ねじと三段目ねじとの高さと略同様の寸法にすることができ、口金部に設けられたねじ部のそれぞれの段のねじの高さを略同様の高さにすることができる。
【００１５】
請求項３に係る発明は、ボトル缶体の口金部の内周面に当接し、かつ外周に前記口金部に形成すべきねじ部を設けるためのねじ形成部を有する中子と、前記口金部の外周面に当接し、かつ外周に中子の前記ねじ形成部と対応する形状のねじ形成部を有する外子とを備え、中子と外子が前記口金部を挟み込みながらボトル缶体の軸心周りに回転し、前記口金部の外周面に対して、一段目ねじと二段目ねじと三段目ねじとの三段からなるねじ山領域を有する巻数のねじ部を形成するねじ成形装置であって、中子の前記ねじ形成部は、口金部の前記ねじ山領域内の二段目ねじを形成する二段目ねじ形成部を、これと隣接する一段目ねじ形成部と三段目ねじ形成部との深さより深くして形成し、外子の前記ねじ形成部は、口金部の前記ねじ山領域内の二段目ねじを形成する二段目ねじ形成部を、これと隣接する一段目ねじ形成部と三段目ねじ形成部との深さより深くして形成していることを特徴とする。
【００１６】
この発明に係るねじ成形装置によれば、中子に設けられているねじ形成部において、口金部のねじ山領域内の二段目ねじを形成する二段目ねじ形成部を、これと隣接する一段目ねじ形成部と三段目ねじ形成部との深さより深くして形成すると共に、外子に設けられているねじ形成部において、口金部のねじ山領域内の二段目ねじを形成する二段目ねじ形成部を、これと隣接する一段目ねじ形成部と三段目ねじ形成部との深さより深くして形成しているので、このような中子と外子で口金部の外周面にねじ部を形成すると、ねじ山領域内の二段目ねじが一段目ねじと三段目ねじとに引張られても、二段目ねじの高さが一段目ねじと三段目ねじとの高さと略同様の寸法にすることができ、口金部に設けられたねじ部のそれぞれの段のねじの高さを略同様の高さにすることができる。
【００１７】
請求項４に係る発明は、開口部に口金部を設けると共に、該口金部の外周面に、一段目ねじと二段目ねじと三段目ねじとの三段からなるねじ山領域を有する巻数のねじ部を設けてなるボトル缶体において、ねじ部の前記ねじ山領域における二段目ねじの高さは、これと隣接する一段目ねじと三段目ねじとの寸法の８５〜１２１％の寸法に形成されていることを特徴とする。
【００１８】
この発明に係るボトル缶体によれば、ねじ部のねじ山領域における二段目ねじの高さが、これと隣接する一段目ねじと三段目ねじとの寸法の８５〜１２１％の寸法に形成されるので、それと隣接する一段目ねじと三段目ねじの高さと略同様全ての段目のねじ山が略均等な高さを有するねじ部を得ることができる。
【００１９】
請求項５に係る発明は、請求項４記載のボトル缶体と、該ボトル缶体の口金部に被着されたキャップとを備えることを特徴とする。
この発明に係るボトルによれば、キャップを被着すると、ボトル缶体内の陽圧でキャップがずれたり、ブリッジ切れが発生するおそれのない良好なボトルが得られる。
【００２０】
【発明の実施の形態】
以下、図面を参照し、この発明の実施の形態について説明する。図１から図７はこの発明の第一の実施の形態に係るねじ成形装置を示す図であって、図１はねじ成形装置と対向する位置にボトル缶体が位置決めされた状態を示す説明図、図２はねじ成形装置がボトル缶体の口金部にねじ部を形成している状態を示す説明図、図３はねじ成形装置の中子を示すねじ形成部の外観図、図４は図３の中子におけるねじ形成部の拡大図、図５はねじ成形装置によってボトル缶体の口金部に形成されたねじ部を示す上から見た説明図、図６はボトル缶体の口金部にねじ部を形成する状態を示す説明図、図７はボトル缶体の口金部に形成されたねじ山領域内の二段目ねじの高さと、口金部におけるねじ部の角度との関係を示す説明図である。
図１及び図２に示す実施形態のねじ成形装置１０を説明する前に、このねじ成形装置１０で取り扱うボトル缶体１は、内部に炭酸飲料、果汁飲料等の内容物を入れるためのものであって、アルミニウム又はアルミニウム合金からなる薄板金属によって有底筒状に形成された後、そのボトル缶体１の開口部に缶胴部よりも小径の口金部２が形成され、その後、口金部２の周囲にねじ形成装置１０によってねじ部３が形成される（図９参照）。
【００２１】
そして、ねじ成形装置１０は、ボトル缶１の口金部２の内周面に当接される中子１１と、外周面に当接される外子１２とを有し、中子１１と外子１２とで口金部２を挟み込みながらボトル缶体１の軸心Ｏ周りに回転することで、口金部２の周囲にねじ部３が形成されるようになっている。
これら中子１１及び外子１２は、図１及び図２に示すように、その外周面にねじ部３を形成するための凹凸状のねじ形成部２１、２２が螺旋状に、しかも互いに対応する形状でそれぞれに形成されており、第一ハウジング４１に対する第二ハウジング４２の位置に応じて径方向に移動するカムローラＣ１、Ｃ２によって径方向に移動されることにより、互いの凹凸形状間にボトル缶体１の口金部２を挟み込んでねじ部３を形成すべく変形させることができるようになっている。
【００２２】
中子１１及び外子１２は、第二ハウジング４２の内方に備えられている。第二ハウジング４２は、第一ハウジング４１に対して先端側に付勢保持されると共に、第三ハウジング４４を固定している。第三ハウジング４４には、押さえ環４７が軸Ｏを中心に回転自在に取り付けられている。押さえ環４７には、ばね４５を介して先端側に付勢された弾性部材４６が取り付けられている。弾性部材４６は、ボトル缶体１に形成されたテーパ状の肩部に沿う円錐面４６ａと缶胴部に沿う円筒面４６ｂとを有し、ボトル缶体１に対してねじ成形装置１０が前進した際にボトル缶体１に押し付けられるようになっている。
【００２３】
なお、図１及び図２において、符号３５はワーク保持部３０側に固定されたストッパー部材であって、このストッパー部材３５に押さえ環４７が当接することにより、押さえ環４７が固定された第三ハウジング４４、第二ハウジング４２及びその内側に備えられた中子１１、外子１２のワーク保持部３０に対する軸方向最前進位置が決定される。
ワーク保持部３０は、詳細に図示されていないが、ボトル缶体１の底部を嵌め込むことでボトル缶体１を保持するダイリング３１と、エアにより膨張してボトル缶体１の缶胴部を締め付け保持するリング状中空弾性部材３２とでチャック機能をなしている。
【００２４】
このねじ形成装置１０は、予め、ワーク保持部３０のダイリング３１に底部が保持されたボトル缶体１が、図１に示すように、対向する位置に位置決めされると、まず、ワーク保持部３０の前進により円筒面４６ｂがボトル缶体１の肩部から缶胴部に嵌め込まれ、次いで、ワーク保持部３０がより前進して押さえ環４７がストッパー部材３５に当接し、第二ハウジング４２及び第三ハウジング４４の前進が停止され、ワーク保持部３０が更に前進して第一ハウジング４１と第二ハウジング４２との軸方向の間隔が狭められる。
【００２５】
このとき、第一ハウジング４１が図２に示すように所定位置まで前進することで、第一ハウジング４１が第二ハウジング４２に対して移動し、カムローラＣ１、Ｃ２が第一ハウジングの斜面４１ａ、４１ｂに沿ってそれぞれ移動すると、それに伴って中子１１がボトル缶体１の口金部２の内周面に移動して当接すると共に、外子１２が口金部２の外周面に移動して当接することにより、中子１１と外子１２とで口金部２を挟み込み、この状態でさらに装置１０全体が軸心Ｏ周りに回転することで、口金部２にねじ部３が形成されるようになっている。
【００２６】
その場合、ボトル缶１の口金部２に形成されるねじ部３は、本例では図１１に示すように巻数が２．２巻として形成される。このねじ部３は、図１１のように、口金部２の外周面において一段目ねじ３ａと二段目ねじ３ｂと三段目ねじ３ｃとの三段からなるねじ山領域Ｌが存在することとなる。
【００２７】
中子１１の外周には、上記ねじ部３を形成するため、図３に示すように凹凸状のねじ形成部２１が設けられ、該ねじ形成部２１には、ねじ部３のねじ山領域Ｌと対応するねじ山領域Ｌ１が設けられている
【００２８】
そして、この実施形態では、ねじ形成部２１において、ねじ山領域Ｌ１の一段目〜三段目ねじ形成部２１ａ〜２１ｃのうち、図４に示すように、二段目ねじ形成部２１ｂのねじ山が一段目ねじ形成部２１ａ及び三段目ねじ形成部２１ｃのねじ山より高く（深く）形成されている。
【００２９】
即ち、中子１１のねじ形成部２１において、口金部２に設けられるねじ部３の一段目ねじ３ａを形成するための一段目ねじ形成部２１ａと、ねじ部３の二段目ねじ３ｂを形成するための二段目ねじ形成部２１ｂと、ねじ部３の三段目ねじ３ｃを形成するための三段目ねじ形成部２１ｃとのうち、二段目ねじ形成部２１ｂのねじ山だけが、一段目ねじ形成部２１ａ及び三段目ねじ形成部２１ｃよりも若干高くして形成されている。
【００３０】
この場合、中子１１におけるねじ山領域Ｌ１としては、図５に示すように、ねじ部３のねじ始まり部３Ａからねじ部３の形成方向と反対方向に−１０°の角度であって、かつそこからねじ終わり方向へ４０°の角度へ至る範囲に相当しており、従って、口金部２に形成されたねじ部３のねじ始まり部３Ａから３５０〜４００°の角度の範囲に相当している。
そして、ねじ山領域Ｌ１内の二段目ねじ形成部２１ｂは、上記の角度範囲内で一段目ねじ形成部２１ａ及び三段目ねじ形成部２１ｃより高く形成されている。
なお、図５において、符号２ａはボトル缶体１の口金部２の内周壁である。
【００３１】
この実施形態のねじ成形装置１０は、上記のように構成されているので、ボトル缶体１にねじ部３を設けるため、図１に示すように、ダイリング３１及びリング状中空弾性部材３２からなるワーク保持部３０に底部が保持されたボトル缶体１が、対向する位置に位置決めされると、ワーク保持部３０の前進により円筒面４６ｂがボトル缶体１の肩部から缶胴部に嵌め込まれ、次いで、ワーク保持部３０がより前進して押さえ環４７がストッパー部材３５に当接し、第二ハウジング４２及び第三ハウジング４４の前進が停止され、ワーク保持部３０が更に前進して第一ハウジング４１と第二ハウジング４２との軸方向の間隔が狭められる。
【００３２】
このとき、第一ハウジング４１が、図２に示すように所定位置まで前進することで、第一ハウジング４１が第二ハウジング４２に対して移動し、カムローラＣ１、Ｃ２が第一ハウジングの斜面４１ａ、４１ｂに沿ってそれぞれ移動し、それに伴って中子１１がボトル缶体の口金部２内周部に移動して当接すると共に、外子１２が口金部２外周部に移動して当接することにより、中子１１と外子１２とで口金部２を挟み込み、この状態でさらに装置全体が軸心Ｏ周りに回転することで、口金部２に図１１のようなねじ部３が形成されることとなる。
【００３３】
その場合、中子１１と外子１２との回転によって２．２巻のねじ部３を口金部２の外周面に沿って形成すると、口金部２においては、ねじ部３の一段目ねじ３ａと三段目ねじ３ｃとが両者の間の二段目ねじ３ｂを、図６に示す鎖線から実線のように、それぞれの方向ａ、ｂに引張ってしまい、二段目ねじ３ｂが小さな寸法に形成されるおそれがある。
【００３４】
しかしながら、上述のように、ねじ成形装置１０の中子１１の外周に設けられたねじ形成部２１において、三段からなるねじ山領域Ｌ１の範囲では、図４に示すように、二段目ねじ形成部２１ｂの高さが一段目ねじ形成部２１ａ及び三段目ねじ形成部２１ｃの高さより若干高い寸法に形成されているので、ねじ部３の形成時、ねじ部３の一段目ねじ３ａ及び三段目ねじ３ｃを形成する口金部２の材料が二段目ねじ３ｂを形成する材料を互いに引張ることがあっても、結果的には、口金部２に形成される二段目ねじ３ｂの高さが他の段のねじ、つまり、一段目ねじ３ａと三段目ねじ３ｃと略同様の高さに形成することができる。
【００３５】
従って、中子１１における二段目ねじ形成部２１ｂだけの高さを大きくすることで、ボトル缶体１に形成されたねじ部３を全て略同様の高さ及び深さにできるので、その後、図１０に示すように、ボトル缶体１の口金部２にキャップ５を被着したとき、内容物の圧力によってキャップ５がずれるのを防止することができるばかりでなく、キャップ５にブリッジ切れが発生することもない。
【００３６】
しかも、中子１１のねじ形成部２１における二段目ねじ形成部２１ｂは、口金部２に形成されるねじ部３の深さが、例えば０．７ｍｍに設定されているとき、そのねじ部のねじ始まり部３Ａからねじ部の方向と反対方向で−１０°の角度で、かつねじ部の方向に沿って４０°の角度の範囲であり、従って、口金部２に設けられたねじ部３の３５０〜４００°の角度範囲に相当している。
【００３７】
因みに、口金部２に形成されたねじ部３のねじ山領域Ｌにおける二段目ねじ３ｂの高さを測定したところ、図７に示すように、３５０°から４００°の範囲では設定深さ（０．７ｍｍ）より、山形状に若干大きな程度となっている。この場合の誤差は、３５０°から４００°の範囲では０．０１〜０．０５ｍｍの微小値であり、キャップ５のずれ等を招くことがないのが確認された。
但し、この実施形態によれば、中子１１の二段目ねじ形成部２１ｂにより、ねじ部３の二段目ねじ３ｂが一段目ねじ３ａ、三段目ねじ３ｃより若干大きく形成された例を示したが、キャップずれやキャップのブリッジ切れを防げる程度の大きさであればよく、従って、設定高さ（０．７ｍｍ）に対し、０．６０〜０８５ｍｍの高さ、つまり、８５〜１２１％の高さとなっていればよく、更に好ましいのは０．６５〜０．７５ｍｍの範囲であればよい。
【００３８】
そして、このねじ成形装置１０によってボトル缶体１の口金部２にねじ部３を形成すると、一段目〜三段目ねじ３ａ〜３ｃが略同様の深さからなるねじ部３を確実に形成することができ、良好なねじ部３を有するボトル缶体１が得られる。
【００３９】
更に、このようなボトル缶体１にキャップ５を被着すれば、キャップ５が圧力が高い内容物を入れても、キャップ５がずれるおそれがなくなり、それだけ信頼性の高いボトルを確実に得ることができる。
【００４０】
図８はこの発明の第二の実施の形態に係るねじ成形装置を示している。
前述した実施形態では、中子１１のねじ形成部２１の二段目ねじ形成部２１ｂを大きくした例を示したが、この実施形態では、中子１１のねじ形成部２１の一段目〜三段目ねじ形成部２１ａ〜２１ｃがそのまま同じ深さに形成される他、外子１２の外周面に設けられている一段目〜三段目ねじ形成部２２ａ〜２２ｃを有するねじ形成部２２において、二段目ねじ形成部２２ｂの深さを、一段目ねじ形成部２２ａ及び三段目ねじ形成部２２ｃのそれより大きく形成したことに特徴を有している。
この場合、二段目ねじ形成部２２ｂの高さとしては、中子１１における二段目ねじ形成部２１ｂの大きさに対応させている。
【００４１】
従って、この実施形態によれば、外子２２の二段目ねじ形成部２２ｂの高さが、他のねじ形成部２２ａ、２２ｃの高さより大きく形成されるので、口金部２にねじ部３を形成すると、結果的に前述した実施形態と同様の作用効果を得ることができる。
【００４２】
なお、図示実施形態では、中子１１のねじ形成部２１における二段目ねじ形成部２１ｂ、及び外子１２のねじ形成部２２における二段目ねじ形成部２２ｂの深さをそれぞれ大きくした例を示したが、例えば、それら二段目ねじ形成部２１ｂと２２ｂとの双方を同時に他のもの（２１ａ、２１ｃと２２ａ、２２ｃ）より大きくしても同様の作用効果を得ることができる。
また、図示実施形態では、ねじ成形装置１０がボトル缶体１の口金部２に２．２巻のねじ部３を形成した例を示したが、巻数をそれ以上増やした場合、例えば２．５巻のような巻数に形成した場合にも適用することができ、図示実施形態に限定されるものではない。
【００４３】
【発明の効果】
以上説明したように、請求項１に係る発明によれば、中子に設けられているねじ形成部において、口金部のねじ山領域内の二段目ねじを形成する二段目ねじ形成部を、これと隣接する一段目ねじ形成部と三段目ねじ形成部との深さより深く形成したので、中子と外子で口金部の外周面にねじ部を形成すると、口金部に設けられたねじ部のそれぞれの段のねじの高さを略同様の高さにすることができる結果、被着したキャップがずれたりブリッジ切れが発生するそおれのない良好なねじ部を形成することができる効果が得られる。
【００４４】
請求項２に係る発明によれば、外子に設けられているねじ形成部において、口金部のねじ山領域内の二段目ねじを形成する二段目ねじ形成部を、これと隣接する一段目ねじ形成部と三段目ねじ形成部との深さよりそれぞれ深く形成したので、中子と外子で口金部の外周面にねじ部を形成すると、口金部に設けられたねじ部のそれぞれの段のねじの高さを略同様の高さにすることができる結果、被着したキャップがずれたりブリッジ切れが発生するそおれのない良好なねじ部を形成することができる効果が得られる。
【００４５】
請求項３に係る発明によれば、中子と外子で口金部の外周面にねじ部を形成したとき、ねじ山領域内の二段目ねじが一段目ねじと三段目ねじとに引張られても、二段目ねじの高さが一段目ねじと三段目ねじとの高さと略同様の寸法にすることができるように構成したので、口金部に設けられたねじ部のそれぞれの段のねじの高さを略同様の高さにすることができる結果、より信頼性の高いねじ部を確実に形成できるという効果が得られる。
【００４６】
請求項４に係る発明によれば、ねじ部のねじ山領域における二段目ねじの高さが、これと隣接する一段目ねじと三段目ねじとの寸法の８５〜１２１％の寸法に形成されるので、全ての段目のねじ山が均等な高さを有するねじ部が得ることができるという効果がある。
【００４７】
請求項５に係る発明によれば、キャップを被着すると、ボトル缶体内の陽圧でキャップがずれたり、ブリッジ切れが発生するおそれのない良好なボトルが得られるという効果がある。
【図面の簡単な説明】
【図１】この発明の第一の実施の形態に係るねじ成形装置を示す図であって、ねじ成形装置と対向する位置にボトル缶体が位置決めされた状態を示す説明図である。
【図２】ねじ成形装置がボトル缶体の口金部にねじ部を形成している状態を示す説明図である。
【図３】ねじ成形装置の中子を示すねじ形成部の外観図である。
【図４】図３の中子におけるねじ形成部の拡大図である。
【図５】成形装置によってボトル缶体の口金部に形成されたねじ部を示す上から見た説明図である。
【図６】ボトル缶体の口金部にねじ部を形成する状態を示す説明図である。
【図７】ボトル缶体の口金部に形成されたねじ山領域内の二段目ねじの高さ（修正高さ）と、口金部におけるねじ部の角度との関係を示す説明図である。
【図８】この発明の第二の実施の形態に係るねじ成形装置を示す図であって、外子に設けられたねじ形成部を示す要部の説明図である。
【図９】ボトル缶体にねじ部を形成するまでの工程を示す説明図である。
【図１０】ねじ部を有するボトル缶体にキャップを被着する説明図である。
【図１１】ボトル缶体に三段からなるねじ部を設けたときの説明図である。
【図１２】従来のねじ成形装置により、ボトル缶体に三段からなるねじ部を形成したときの問題点を示す要部の説明図である。
【符号の説明】
１　　ボトル缶体
２　　口金部
３　　ねじ部
３ａ　　一段目ねじ
３ｂ　　二段目ねじ
３ｃ　　三段目ねじ
１０　　ねじ成形装置
１１　　中子
１２　　外子
２１　　中子のねじ形成部
２２　　外子のねじ形成部
２１ｂ　　中子のねじ形成部における二段目ねじ形成部
２２ｂ　　外子のねじ形成部における二段目ねじ形成部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a screw forming apparatus for forming a screw portion for attaching a cap to a base portion of a bottle can body, a bottle can body having the screw portion, and a cap attached to the base portion of the bottle can body. Related to bottles that have been made.
[0002]
[Prior art]
A so-called bottle can body obtained by drawing a metal can body is formed by forming a base portion at an opening of the bottle can body formed on a bottomed cylinder, and a cap is attached to an outer periphery of the base portion. Screw portion is formed.
[0003]
In order to manufacture a bottle can having such a screw portion, when a bottomed cylindrical bottle can is formed in advance, the opening of the bottle can is opened as shown in FIG. The diameter is once reduced to form the base 2, and then the diameter is increased by a predetermined distance from the opening end of the base 2 to form the enlarged diameter 2 ′ as shown in FIG. A screw portion 3 is formed at a fixed distance from the opening end by a screw forming device as shown in FIG. In this case, when the screw portion 3 is formed in the base 2, the bulging portion 4 is formed by leaving an enlarged portion where the screw portion 3 is not formed.
[0004]
Although not shown, the conventional screw forming apparatus has a bottle can body with a core abutting on the inner peripheral surface of the base portion 2 and an outer core abutting on the outer peripheral surface of the base portion 2 while sandwiching the base portion 2 therebetween. The screw portion 3 is formed on the outer periphery of the base portion 2 by rotating about the axis of the shaft 1. In this case, the number of turns of the screw portion 3 formed on the base 2 is about 1.7 turns as shown in FIG. The contents of the bottle can body 1 on which the screw portion 3 is formed are then put through various steps, and then the cap 5 shown in FIG. 10 is attached and hermetically sealed.
[0005]
[Problems to be solved by the invention]
As described above, in the conventional screw forming apparatus, the core that contacts the inner peripheral surface of the base 2 of the bottle can 1 and the outer core that contacts the outer peripheral surface of the base 2 sandwich the bottle can with each other. By rotating around the axis, the screw part 3 having 1.7 turns is formed on the base part 2 whose diameter has been increased.
[0006]
However, when the number of turns of the screw portion is about 1.7 turns, as shown in FIG. 10, a portion having two screw portions 3 on a peripheral surface of the base portion 2 and a portion having only one screw portion 3. And there was a problem with the difference in the number. That is, if the number of turns is the above, when the cap 5 is attached to the bottle can 1 and the inside of the bottle can 1 is made to have a positive pressure, a pressure for pushing up the cap 5 is applied, and the cap 5 is displaced upward. . Therefore, since the cap 5 is biased with respect to the bottle can 1, the bridge 7 provided between the scores 6 and 6 on the opening end side of the cap 5 is pulled and broken, and so-called bridge breakage occurs. There was a malfunction that occurred.
[0007]
In order to solve the above problem, as shown in FIG. 11, an attempt has been made to increase the number of turns of the screw portion 3 to 2.2 turns. When the screw part 3 having 2.2 turns is formed on the base part 2 of the bottle can body 1 in this manner, the screw part 3 is connected to the first screw 3a between the screw start part and the screw end part of the screw part 3. There will be a three-step thread region L like the second-stage screw 3b and the third-stage screw 3c.
[0008]
However, when 2.2 turns of the screw portion 3 are formed in the bottle can 1, in the thread region L having three stages, the first stage screw 3a and the third stage screw 3c of the bottle can 1 are formed at the time of molding. As a result, the second screw 3b is pulled. That is, in the conventional screw forming apparatus, when the screw part 3 of 2.2 turns is formed in the base part 2, as shown in FIG. 12, the material of the base part 2 forming the first-stage screw 3a causes the second-stage screw to be formed. 3b is pulled in the direction of the first screw 3a as shown by the arrow a, and the material forming the second screw 3b is changed by the material of the base 2 forming the third screw 3c to the arrow b. Is pulled in the direction of the third screw 3c.
[0009]
Therefore, the crest (depth) of the second-stage screw 3b becomes shallower than the set location indicated by the chain line, and is slightly recessed as shown by the solid line. As a result, the second-stage screw 3b is There was a problem that the dimensions were smaller than the third thread 3a, 3c.
If the second screw 3b is formed smaller than the first and third screws 3a and 3c in this manner, a uniform sealing force of the cap 5 cannot be obtained. In addition, when the drinking water is filled and the cap 5 is attached, there is a problem that the cap 5 shifts when the internal pressure of the drinking water increases.
[0010]
The present invention has been made in view of such circumstances, and an object of the present invention is to ensure that the screw portion is substantially along the length even if the number of turns of the screw portion is increased so that the thread region becomes three steps. Another object of the present invention is to provide a screw forming device which can be formed at the same height (depth) and does not cause the cap to be displaced from the bottle can by the pressure of the contents. An object of the present invention is to provide a bottle can and a bottle having a formed screw portion.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention proposes the following means.
The invention according to claim 1 is a core having a screw forming portion for contacting an inner peripheral surface of a mouth portion of a bottle can body and providing a thread portion to be formed on the mouth portion on an outer periphery, and the mouth portion. And an outer core having a threaded portion having a shape corresponding to the threaded portion of the core on the outer periphery thereof, and the core and the outer core sandwiching the base portion while holding the shaft of the bottle can body. A screw forming device that rotates around a center and forms a thread portion having a number of turns having a three-stage thread region of a first-stage screw, a second-stage screw, and a third-stage screw on the outer peripheral surface of the base portion Wherein the screw forming portion of the core includes a second-stage screw forming portion forming a second-stage screw in the thread region of the base portion, and a first-stage screw forming portion adjacent thereto and a third-stage screw forming portion. It is characterized in that it is formed to be deeper than the depth with the screw forming part.
[0012]
ADVANTAGE OF THE INVENTION According to the screw forming apparatus which concerns on this invention, in the screw formation part provided in the core, the 2nd-stage screw formation part which forms the 2nd-stage screw in the thread region of a base part is adjacent to this. Since the thread is formed deeper than the depth of the first thread forming part and the third thread forming part, when the thread is formed on the outer peripheral surface of the base with the core and the outer core, the two steps in the thread area Even if the first thread is pulled by the first thread and the third thread, the height of the second thread can be approximately the same as the height of the first thread and the third thread. The height of the screw of each step of the threaded portion provided at the same height can be made substantially the same.
[0013]
The invention according to claim 2 is a core having a screw forming portion for contacting an inner peripheral surface of a mouth portion of a bottle can body and providing a thread portion to be formed on the mouth portion on an outer periphery, and the mouth portion. And an outer core having a threaded portion having a shape corresponding to the threaded portion of the core on the outer periphery thereof, and the core and the outer core sandwiching the base portion while holding the shaft of the bottle can body. A screw forming device that rotates around a center and forms a thread portion having a number of turns having a three-stage thread region of a first-stage screw, a second-stage screw, and a third-stage screw on the outer peripheral surface of the base portion Wherein the screw forming portion of the outer core includes a second-stage screw forming portion that forms a second-stage screw in the thread region of the base portion, and a first-stage screw forming portion adjacent thereto and a third-stage screw forming portion. It is characterized in that it is formed to be deeper than the depth with the screw forming part.
[0014]
ADVANTAGE OF THE INVENTION According to the screw forming apparatus which concerns on this invention, in the screw formation part provided in the outer arm, the 2nd-stage screw formation part which forms the 2nd-stage screw in the thread region of a base part is adjacent to this. Since the thread is formed deeper than the depth of the first thread forming part and the third thread forming part, when the thread is formed on the outer peripheral surface of the base with the core and the outer core, the two steps in the thread area Even if the first thread is pulled by the first thread and the third thread, the height of the second thread can be approximately the same as the height of the first thread and the third thread. The height of the screw of each step of the threaded portion provided at the same height can be made substantially the same.
[0015]
The invention according to claim 3 is a core having a screw forming portion for contacting an inner peripheral surface of a mouth portion of a bottle can body and providing a thread portion to be formed on the mouth portion on an outer periphery, and the mouth portion. And an outer core having a threaded portion having a shape corresponding to the threaded portion of the core on the outer periphery thereof, and the core and the outer core sandwiching the base portion while holding the shaft of the bottle can body. A screw forming device that rotates around a center and forms a thread portion having a number of turns having a three-stage thread region of a first-stage screw, a second-stage screw, and a third-stage screw on the outer peripheral surface of the base portion Wherein the screw forming portion of the core includes a second-stage screw forming portion forming a second-stage screw in the thread region of the base portion, and a first-stage screw forming portion adjacent thereto and a third-stage screw forming portion. It is formed to be deeper than the depth with the screw forming portion, and the screw forming portion of the outer core is formed in the screw thread region of the base portion. The second stage screw forming portion for forming a stage screw, characterized in that it to be formed deeply than the depth of the first stage thread forming portion and a three-stage screw forming portions adjacent.
[0016]
ADVANTAGE OF THE INVENTION According to the screw forming apparatus which concerns on this invention, in the screw formation part provided in the core, the 2nd-stage screw formation part which forms the 2nd-stage screw in the thread region of a base part is adjacent to this. The first-stage screw forming portion and the third-stage screw forming portion are formed to be deeper than the depth of the first-stage screw forming portion, and the second-stage screw in the thread region of the base portion is formed in the screw forming portion provided on the outer arm. Since the second-stage screw forming portion is formed deeper than the depth of the first-stage screw forming portion and the third-stage screw forming portion adjacent to the second-stage screw forming portion, the outer periphery of the base portion is formed by such a core and an outer core. If the thread is formed on the surface, the height of the second screw will be higher than that of the first and third screws even if the second screw in the thread area is pulled by the first and third screws. The height of the screw of each step of the screw part provided in the base part can be made approximately the same size as the height of It may have the same height.
[0017]
The invention according to claim 4 is the number of turns in which a mouth portion is provided in the opening portion and the outer peripheral surface of the mouth portion has a three-stage thread region of a first-stage screw, a second-stage screw, and a third-stage screw. The height of the second stage screw in the thread region of the thread portion is 85 to 121% of the dimension of the first stage screw and the third stage screw adjacent thereto. It is characterized by being formed in dimensions.
[0018]
According to the bottle can body of the present invention, the height of the second-stage screw in the thread region of the thread portion is 85 to 121% of the dimension of the first-stage screw and the third-stage screw adjacent thereto. Since it is formed, it is possible to obtain a thread portion in which the threads of all the stages have substantially the same height as the height of the first stage screw and the third stage screw adjacent thereto.
[0019]
According to a fifth aspect of the present invention, there is provided the bottle can according to the fourth aspect, and a cap attached to a base of the bottle can.
ADVANTAGE OF THE INVENTION According to the bottle which concerns on this invention, when a cap is attached, the favorable bottle which does not have a possibility that a cap shift | deviates by positive pressure in a bottle can body, or a bridge breakage will generate | occur | produce is obtained.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 7 are views showing a screw forming apparatus according to a first embodiment of the present invention, and FIG. 1 is an explanatory view showing a state where a bottle can is positioned at a position facing the screw forming apparatus. FIG. 2 is an explanatory view showing a state in which the screw forming device forms a screw portion in a mouth portion of a bottle can body, FIG. 3 is an external view of a screw forming portion showing a core of the screw forming device, and FIG. 3 is an enlarged view of a screw forming portion of the core of FIG. 3, FIG. 5 is an explanatory view from above showing a screw portion formed on the base of the bottle can by the screw forming apparatus, and FIG. 6 is a top view of the base of the bottle can. FIG. 7 is an explanatory diagram showing a state in which a screw portion is formed. FIG. 7 is a diagram showing a relationship between the height of a second-stage screw in a thread region formed in a mouth portion of a bottle can body and the angle of the screw portion in the mouth portion. FIG.
Before explaining the screw forming apparatus 10 of the embodiment shown in FIGS. 1 and 2, the bottle can 1 handled by the screw forming apparatus 10 is for putting therein contents such as carbonated drinks and fruit juice drinks. Then, after being formed into a bottomed cylindrical shape by a thin metal plate made of aluminum or an aluminum alloy, a base 2 having a smaller diameter than the can body is formed at the opening of the bottle can body 1, and thereafter, the base 2 is formed. The threaded portion 3 is formed by the threading device 10 around the periphery of the screw (see FIG. 9).
[0021]
The screw forming apparatus 10 includes a core 11 that is in contact with the inner peripheral surface of the base 2 of the bottle can 1 and an outer core 12 that is in contact with the outer peripheral surface. By rotating around the axis O of the bottle can 1 while sandwiching the base 2 with the base 12, the screw 3 is formed around the base 2.
As shown in FIGS. 1 and 2, the core 11 and the outer core 12 have screw-forming portions 21, 22 having an uneven shape for forming the screw portion 3 on the outer peripheral surface thereof, and correspond to each other in a spiral shape. The bottle cans are formed between the concave and convex shapes by being moved in the radial direction by the cam rollers C1 and C2 which are formed in the respective shapes and move in the radial direction according to the position of the second housing 42 with respect to the first housing 41. The base 2 of the body 1 can be deformed so as to form the screw 3 by sandwiching the base 2.
[0022]
The core 11 and the outer core 12 are provided inside the second housing 42. The second housing 42 is biased and held to the distal end side with respect to the first housing 41 and fixes the third housing 44. A retaining ring 47 is attached to the third housing 44 so as to be rotatable about an axis O. An elastic member 46 urged toward the distal end via a spring 45 is attached to the press ring 47. The elastic member 46 has a conical surface 46a along a tapered shoulder formed on the bottle can 1, and a cylindrical surface 46b along the can body. When pressed, it is pressed against the bottle can 1.
[0023]
In FIGS. 1 and 2, reference numeral 35 denotes a stopper member fixed to the work holding portion 30, and the pressing ring 47 abuts on the stopper member 35 to fix the third pressing member 47. The axially most advanced positions of the housing 44, the second housing 42, and the core 11 and the outer core 12 provided inside the second housing 42 with respect to the work holding portion 30 are determined.
Although not shown in detail, the work holding unit 30 includes a die ring 31 that holds the bottle can 1 by fitting the bottom of the bottle can 1, and a can body of the bottle can 1 that is expanded by air. And a ring-shaped hollow elastic member 32 for tightening and holding a chuck function.
[0024]
As shown in FIG. 1, the screw forming device 10 first moves the bottle can 1 whose bottom is held by the die ring 31 of the work holding unit 30 to the opposing position as shown in FIG. By the advance of 30, the cylindrical surface 46b is fitted into the can body from the shoulder of the bottle can 1, and then the work holding part 30 advances further, the holding ring 47 abuts against the stopper member 35, and the second housing 42 and The advance of the third housing 44 is stopped, and the work holding unit 30 further advances, so that the axial distance between the first housing 41 and the second housing 42 is reduced.
[0025]
At this time, as the first housing 41 advances to a predetermined position as shown in FIG. 2, the first housing 41 moves with respect to the second housing 42, and the cam rollers C1 and C2 move on the slopes 41a and 41b of the first housing. Along, the core 11 moves along with it and comes into contact with the inner peripheral surface of the base 2 of the bottle can 1, and the outer core 12 moves and comes into contact with the outer peripheral surface of the base 2. Thereby, the base 2 is sandwiched between the core 11 and the outer core 12, and in this state, the entire device 10 further rotates around the axis O, so that the screw 3 is formed in the base 2. ing.
[0026]
In this case, the screw portion 3 formed on the base portion 2 of the bottle can 1 is formed to have 2.2 turns as shown in FIG. 11 in this example. As shown in FIG. 11, the screw portion 3 has a thread region L including three stages of a first-stage screw 3a, a second-stage screw 3b, and a third-stage screw 3c on the outer peripheral surface of the base 2. Become.
[0027]
In order to form the screw portion 3 on the outer periphery of the core 11, an uneven screw forming portion 21 is provided as shown in FIG. 3, and the screw forming portion 21 has a thread region L of the screw portion 3. And a thread region L1 corresponding to
In this embodiment, as shown in FIG. 4, among the first to third thread forming portions 21 a to 21 c of the thread region L <b> 1 in the screw forming portion 21, the thread of the second thread forming portion 21 b is formed. Are formed higher (deeper) than the threads of the first-stage screw forming portion 21a and the third-stage screw forming portion 21c.
[0029]
That is, in the screw forming portion 21 of the core 11, a first-stage screw forming portion 21a for forming the first-stage screw 3a of the screw portion 3 provided in the base 2 and a second-stage screw 3b of the screw portion 3 are formed. Of the second-stage screw forming portion 21b and the third-stage screw forming portion 21c of forming the third-stage screw 3c of the screw portion 3, only the threads of the second-stage screw forming portion 21b are: It is formed slightly higher than the first-stage screw forming portion 21a and the third-stage screw forming portion 21c.
[0030]
In this case, as shown in FIG. 5, the thread region L1 in the core 11 has an angle of −10 ° from the screw start portion 3A of the screw portion 3 in the direction opposite to the forming direction of the screw portion 3, and From there, it corresponds to a range of an angle of 40 ° to the screw end direction, and thus corresponds to a range of an angle of 350 to 400 ° from the screw start part 3A of the screw part 3 formed in the base part 2. .
The second-stage screw forming portion 21b in the thread region L1 is formed higher than the first-stage screw forming portion 21a and the third-stage screw forming portion 21c within the above-mentioned angle range.
In FIG. 5, reference numeral 2a denotes the inner peripheral wall of the base 2 of the bottle can 1.
[0031]
Since the screw forming apparatus 10 of this embodiment is configured as described above, in order to provide the screw portion 3 in the bottle can 1, as shown in FIG. When the bottle can 1 whose bottom is held by the work holding portion 30 is positioned at an opposing position, the cylindrical surface 46b is fitted into the can body from the shoulder of the bottle can 1 by the advance of the work holding portion 30. Then, the work holding portion 30 further advances, the holding ring 47 abuts on the stopper member 35, the advance of the second housing 42 and the third housing 44 is stopped, and the work holding portion 30 further advances to the first position. The axial distance between the housing 41 and the second housing 42 is reduced.
[0032]
At this time, as the first housing 41 advances to a predetermined position as shown in FIG. 2, the first housing 41 moves with respect to the second housing 42, and the cam rollers C1 and C2 move to the slopes 41a of the first housing, 41b, the core 11 moves along with the inner peripheral part of the base 2 of the bottle can and comes into contact therewith, and the outer core 12 moves and contacts the outer peripheral of the base 2 The screw part 3 as shown in FIG. 11 is formed on the base part 2 by sandwiching the base part 2 between the core 11 and the outer core 12 and further rotating the entire device around the axis O in this state. It becomes.
[0033]
In this case, when the screw part 3 of 2.2 turns is formed along the outer peripheral surface of the base part 2 by the rotation of the core 11 and the outer part 12, in the base part 2, the first-stage screw 3 a of the screw part 3 is formed. The third-stage screw 3c pulls the second-stage screw 3b therebetween in the directions a and b as shown by the solid line from the chain line in FIG. May be done.
[0034]
However, as described above, in the screw forming portion 21 provided on the outer periphery of the core 11 of the screw forming device 10, in the range of the thread region L1 having three steps, as shown in FIG. Since the height of the forming portion 21b is formed to be slightly higher than the height of the first-stage screw forming portion 21a and the third-stage screw forming portion 21c, the first-stage screw 3a and the first-stage screw 3a of the screw portion 3 are formed when the screw portion 3 is formed. Even if the material of the base portion 2 forming the third-stage screw 3c pulls the material forming the second-stage screw 3b mutually, as a result, the material of the second-stage screw 3b formed in the base portion 2 is reduced. The height of the screw can be formed to be substantially the same as the height of the other screws, that is, the first screw 3a and the third screw 3c.
[0035]
Accordingly, by increasing the height of only the second-stage screw forming portion 21b of the core 11, all the screw portions 3 formed on the bottle can 1 can have substantially the same height and depth. As shown in FIG. 10, when the cap 5 is attached to the base 2 of the bottle can 1, not only can the cap 5 be prevented from being displaced by the pressure of the contents, but also the bridge of the cap 5 can be broken. It does not occur.
[0036]
Moreover, when the depth of the screw portion 3 formed in the base 2 is set to, for example, 0.7 mm, the second-step screw forming portion 21b of the screw forming portion 21 of the core 11 The angle from the screw start part 3A to the direction opposite to the direction of the screw part is -10 °, and the angle is 40 ° along the direction of the screw part. This corresponds to an angle range of 350 to 400 °.
[0037]
Incidentally, when the height of the second stage screw 3b in the thread region L of the screw portion 3 formed in the base 2 was measured, as shown in FIG. 0.7 mm), it is slightly larger in a mountain shape. The error in this case was a small value of 0.01 to 0.05 mm in the range of 350 ° to 400 °, and it was confirmed that the cap 5 did not shift.
However, according to this embodiment, an example in which the second-stage screw 3b of the screw portion 3 is formed slightly larger than the first-stage screw 3a and the third-stage screw 3c by the second-stage screw forming portion 21b of the core 11 is described. Although shown, it is sufficient if the size is such as to prevent cap displacement and breakage of the bridge of the cap. Therefore, the height is 0.60 to 085 mm with respect to the set height (0.7 mm), that is, 85 to 121%. , And more preferably in the range of 0.65 to 0.75 mm.
[0038]
When the screw part 3 is formed on the base part 2 of the bottle can body 1 by the screw forming apparatus 10, the first to third screws 3a to 3c surely form the screw part 3 having substantially the same depth. As a result, a bottle can 1 having a good screw portion 3 is obtained.
[0039]
Furthermore, if the cap 5 is attached to such a bottle can 1, even if the cap 5 is filled with high-pressure contents, there is no risk of the cap 5 being displaced, and a reliable bottle can be reliably obtained. Can be.
[0040]
FIG. 8 shows a screw forming apparatus according to a second embodiment of the present invention.
In the above-described embodiment, an example is shown in which the second-stage screw forming portion 21b of the screw forming portion 21 of the core 11 is enlarged, but in this embodiment, the first to third steps of the screw forming portion 21 of the core 11 are illustrated. In addition to the external thread forming portions 21a to 21c being formed at the same depth as they are, the screw forming portion 22 having the first to third-stage screw forming portions 22a to 22c provided on the outer peripheral surface of the outer arm 12, It is characterized in that the depth of the first-stage screw forming portion 22b is larger than that of the first-stage screw forming portion 22a and the third-stage screw forming portion 22c.
In this case, the height of the second-stage screw forming portion 22b corresponds to the size of the second-stage screw forming portion 21b of the core 11.
[0041]
Therefore, according to this embodiment, the height of the second-stage screw forming portion 22b of the outer arm 22 is formed larger than the heights of the other screw forming portions 22a and 22c. When formed, the same operation and effect as those of the above-described embodiment can be obtained.
[0042]
In the illustrated embodiment, an example in which the depth of the second-stage screw forming portion 21b of the thread forming portion 21 of the core 11 and the depth of the second-stage screw forming portion 22b of the screw forming portion 22 of the outer core 12 are respectively increased. Although shown, for example, a similar effect can be obtained even if both of the second-stage screw forming portions 21b and 22b are simultaneously made larger than the other ones (21a, 21c and 22a, 22c).
Further, in the illustrated embodiment, the screw forming apparatus 10 has formed the screw part 3 of 2.2 turns on the base part 2 of the bottle can body 1. However, when the number of turns is further increased, for example, 2.5 times The present invention can be applied to a case where the number of turns is equal to the number of turns, and is not limited to the illustrated embodiment.
[0043]
【The invention's effect】
As described above, according to the first aspect of the present invention, in the screw forming portion provided in the core, the second-stage screw forming portion for forming the second-stage screw in the thread region of the base portion is provided. Since it was formed deeper than the depth of the first-stage screw forming portion and the third-stage screw forming portion adjacent thereto, when a thread portion was formed on the outer peripheral surface of the base portion with the core and the outer core, the screw portion was provided on the base portion. As a result, the heights of the screws in the respective steps of the screw portion can be made substantially the same. As a result, it is possible to form a good screw portion without displacement of the applied cap or breakage of the bridge. The effect is obtained.
[0044]
According to the invention according to claim 2, in the screw forming portion provided on the outer core, the second-stage screw forming portion for forming the second-stage screw in the thread region of the mouthpiece portion is a single-step adjacent to the second-stage screw forming portion. Since the thread was formed deeper than the depth of the eye screw forming part and the third thread forming part, when the screw part was formed on the outer peripheral surface of the base part with the core and the outer core, each of the screw parts provided in the base part was formed. As a result, the height of the screw of the step can be made substantially the same. As a result, it is possible to obtain an effect that a good screw portion can be formed without displacement of the attached cap or breakage of the bridge.
[0045]
According to the invention according to claim 3, when the core portion and the outer core form a screw portion on the outer peripheral surface of the base portion, the second-stage screw in the thread region is pulled by the first-stage screw and the third-stage screw. Even if it is, the height of the second-stage screw is configured to be approximately the same as the height of the first-stage screw and the third-stage screw. As a result that the heights of the screws of the step can be made substantially the same, an effect that a more reliable screw portion can be reliably formed can be obtained.
[0046]
According to the invention according to claim 4, the height of the second-stage screw in the thread region of the thread portion is formed to be 85 to 121% of the size of the first-stage screw and the third-stage screw adjacent thereto. Therefore, there is an effect that a thread portion in which the threads of all the steps have an equal height can be obtained.
[0047]
According to the fifth aspect of the present invention, when the cap is attached, there is an effect that a good bottle can be obtained without the possibility of the cap being displaced by positive pressure in the bottle can body or the occurrence of bridge breakage.
[Brief description of the drawings]
FIG. 1 is a view showing a screw forming apparatus according to a first embodiment of the present invention, and is an explanatory view showing a state where a bottle can is positioned at a position facing the screw forming apparatus.
FIG. 2 is an explanatory view showing a state in which a screw forming device forms a screw portion on a mouth portion of a bottle can body.
FIG. 3 is an external view of a screw forming section showing a core of the screw forming apparatus.
FIG. 4 is an enlarged view of a thread forming portion of the core of FIG. 3;
FIG. 5 is an explanatory diagram viewed from above showing a screw portion formed on the mouth portion of the bottle can body by the molding apparatus.
FIG. 6 is an explanatory view showing a state in which a screw portion is formed in a base portion of the bottle can body.
FIG. 7 is an explanatory diagram showing a relationship between a height (correction height) of a second-stage screw in a thread region formed in a mouth portion of a bottle can body and an angle of the screw portion in the mouth portion.
FIG. 8 is a view showing a screw forming apparatus according to a second embodiment of the present invention, and is an explanatory view of a main part showing a screw forming portion provided on an outer core.
FIG. 9 is an explanatory view showing a process until a thread portion is formed on the bottle can body.
FIG. 10 is an explanatory view of attaching a cap to a bottle can having a screw portion.
FIG. 11 is an explanatory view when a three-stage screw portion is provided on a bottle can body.
FIG. 12 is an explanatory view of a main part showing a problem when a three-stage screw portion is formed on a bottle can body by a conventional screw forming apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bottle can body 2 Base part 3 Screw part 3a First-stage screw 3b Second-stage screw 3c Third-stage screw 10 Screw forming device 11 Core 12 Outer core 21 Core screw forming part 22 Outer screw forming part 21b Medium Second-stage screw forming section 22b in outer thread forming section Second-stage screw forming section in outer screw forming section

Claims

A core having a screw forming portion for providing a screw portion to be formed on the base portion on the outer periphery, abutting against the inner peripheral surface of the base portion of the bottle can body, and abutting on the outer peripheral surface of the base portion, and An outer core having a screw forming portion having a shape corresponding to the screw forming portion of the core on the outer periphery,
The core and the outer core are rotated around the axis of the bottle body while sandwiching the base, and the outer peripheral surface of the base is formed of a first-stage screw, a second-stage screw, and a third-stage screw. A screw forming apparatus for forming a thread portion having a number of turns having a thread region comprising:
The screw forming portion of the core includes a second-stage screw forming portion that forms a second-stage screw in the thread region of the base portion, and a first-stage screw forming portion and a third-stage screw forming portion adjacent thereto. A screw forming apparatus characterized in that the screw forming apparatus is formed so as to be deeper than the depth of the screw.

A core having a screw forming portion for providing a screw portion to be formed on the base portion on the outer periphery, abutting against the inner peripheral surface of the base portion of the bottle can body, and abutting on the outer peripheral surface of the base portion, and An outer core having a screw forming portion having a shape corresponding to the screw forming portion of the core on the outer periphery,
The core and the outer core are rotated around the axis of the bottle body while sandwiching the base, and the outer peripheral surface of the base is formed of a first-stage screw, a second-stage screw, and a third-stage screw. A screw forming apparatus for forming a thread portion having a number of turns having a thread region comprising:
The screw forming portion of the outer core includes a second-stage screw forming portion that forms a second-stage screw in the thread region of the base portion, and a first-stage screw forming portion and a third-stage screw forming portion adjacent thereto. A screw forming apparatus characterized in that the screw forming apparatus is formed so as to be deeper than the depth of the screw.

A core having a screw forming portion for providing a screw portion to be formed on the base portion on the outer periphery, abutting against the inner peripheral surface of the base portion of the bottle can body, and abutting on the outer peripheral surface of the base portion, and An outer core having a screw forming portion having a shape corresponding to the screw forming portion of the core on the outer periphery,
The core and the outer core are rotated around the axis of the bottle body while sandwiching the base, and the outer peripheral surface of the base is formed of a first-stage screw, a second-stage screw, and a third-stage screw. A screw forming apparatus for forming a thread portion having a number of turns having a thread region comprising:
The screw forming portion of the core includes a second-stage screw forming portion that forms a second-stage screw in the thread region of the base portion, and a first-stage screw forming portion and a third-stage screw forming portion adjacent thereto. Formed deeper than the depth of
The screw forming portion of the outer core includes a second-stage screw forming portion that forms a second-stage screw in the thread region of the base portion, and a first-stage screw forming portion and a third-stage screw forming portion adjacent thereto. A screw forming apparatus characterized in that the screw forming apparatus is formed so as to be deeper than the depth of the screw.

A mouth part is provided in the opening, and a screw part having a number of turns having a thread region consisting of three steps of a first-stage screw, a second-stage screw, and a third-stage screw is provided on the outer peripheral surface of the mouth portion. In the bottle can body,
The height of the second stage screw in the thread region of the thread portion is formed to be 85 to 121% of the dimension of the first stage screw and the third stage screw adjacent thereto. Can body.

A bottle comprising: the bottle can according to claim 4; and a cap attached to a base of the bottle can.