JP3869565B2

JP3869565B2 - Pipe fitting

Info

Publication number: JP3869565B2
Application number: JP32217098A
Authority: JP
Inventors: 和士丸山; 治之永吉; 英司津留
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 1997-12-04
Filing date: 1998-11-12
Publication date: 2007-01-17
Anticipated expiration: 2018-11-12
Also published as: JPH11223284A

Description

【０００１】
【発明の属する技術分野】
本発明は、油井管、土木杭管等のテーパねじ継手において、ピンのテーパ雄ねじ部をボックス又はカップリングのテーパ雌ねじ部に垂直方向に差し込み、引き続き回転して締め込む際に、作業性を向上可能な管継手に関する。
【０００２】
【従来の技術】
従来、油井管、土木杭管等の管継手として、図２１に示すように、管５０のピン５１のテーパ雄ねじ部５２と短管５３のボックス５４のテーパ雌ねじ部５５が嵌合する管用テーパ角ねじ（台形ねじ、バットレスねじを含む）継手が使用されている。この管用テーパ角ねじ継手のねじ込み開始の状況を拡大図で示している。
管用テーパ角ねじ継手のスタビング性を判りやすく説明するために、テーパ雄ねじ部５２及びテーパ雌ねじ部５５の雄、雌ねじ山５６、５７の形状を同一とし、それぞれの雄、雌ねじ山頂面５８、５９はテーパ面Ｔf に平行とする。図に示す嵌合断面図は、まさに雄ねじ山５６が雌ねじ山５７に噛み込もうとするところを示している。つまり、テーパ雄ねじ部５２の雄ねじ山頂面５８を連ねたテーパ面とテーパ雌ねじ部５５の雌ねじ山頂面５９を連ねたテーパ面が丁度一致しており、かつ雄ねじ山５６が雌ねじ山５７の谷部６０に位置するように、テーパ雄ねじ部５２の円周方向位置とテーパ雌ねじ部５５の円周方向位置を揃えた図としている。図から明らかなように、このままの状態ではテーパ雄ねじ部５２をテーパ雌ねじ部５５にねじ込むことは不可能である。
【０００３】
ここで、管用テーパ角ねじ継手のスタビング性について、図２２（Ｂ）に示すように、油井管ねじとして広く用いられているＡＰＩバットレスねじ継手の場合を例にして、テーパ雄ねじ部６１がテーパ雌ねじ部６２に差し込まれた後、いかにして雄、雌ねじ山６３、６４がねじ込まれる仕掛けになっているかを説明する。
ＡＰＩバットレスねじ要素は、テーパＴ＝１／１６（又は６２．５ｍｍ／ｍ、直径に対する変化率）、ピッチＰ＝５．０８ｍｍ、ねじ山高さＨ＝１．５７５ｍｍ、スタビングフランク角η＝１０°、ロードフランク角γ＝３°、雄、雌ねじ山頂面６５、６６の直線部はテーパ面Ｔp （即ち、ピッチライン）に平行、雄、雌ねじ山頂面６５、６６のコーナＲがそれぞれ０．７６ｍｍ又は０．２０ｍｍなどを特徴としている。
図２２（Ａ）はテーパ雄ねじ部６１とテーパ雌ねじ部６２がねじ込みのために最も都合の良い周方向に填まり込んだ状況を示している。前記管用テーパ角ねじ継手の場合とは異なり、テーパ雌ねじ部６２の谷部６７の開口部６８は雄ねじ山６３の雄ねじ山頂面６５より幅広く、かつコーナＲを採ることでその差が広くなるようにできており、この状態からテーパ雄ねじ部６１を鉛直に落下させると、テーパ雄ねじ部６１の雄ねじ山６３のコーナ部６９は、テーパ雌ねじ部６２の雌ねじ山６４のコーナ部７０に僅かに載ることができ、その状態からテーパ雄ねじ部６１を回せば、テーパ雄ねじ部６１は螺旋に沿って填まり込んでいくことになる。
【０００４】
また、このようにテーパ雄ねじ部６１がテーパ雌ねじ部６２に填まり込むためには、必ずしも雄ねじ列と雌ねじ列の相対位置は図２２（Ａ）の通りでなくてもよく、雄ねじ山６３のスタビングフランク面７１のコーナＲがテーパ雌ねじ部６２のスタビングフランク面７２のコーナＲに接するところまで、テーパ雄ねじ部６１を図２２（Ａ）の位置よりテーパに沿って下方にずらせた位置でも、テーパ雄ねじ部６１はテーパ雌ねじ部６２に填まり込むことができる。つまり、このずれに相当する周方向角度の分だけ、テーパ雄ねじ部６１をテーパ雌ねじ部６２に差し込んだ時、旨くねじ込むための周方向範囲に裕度を持たせることができる。
通常の差し込み、ねじ込み開始作業では、テーパ雄ねじ部６１をテーパ雌ねじ部６２に差し込み、旨くテーパ雄ねじ部６１の雄ねじ山６３をテーパ雌ねじ部６２の雌ねじ山６４に預けることのできる前記周方向位置まで、テーパ雄ねじ部６１を回転させる。この時は、まだ雄ねじ山６３と雌ねじ山６４は噛み合っていないので、テーパ雄、雌ねじ部６１、６２のそれぞれの軸心が一致していないとかじりを起こすこともあり、またコンダクターケーシングのように直径の大きい鋼管では、回転角が大きいとねじ込み位置探索作業も大変である。従って、雄ねじ山６３と雌ねじ山６４が噛み込める周方向位置の範囲が広い程、適切な場所まで回転させる回転角を小さくすることができ、スタビング性の良いテーパねじ継手といえる。また、テーパ雌ねじ部６２の谷部６７の開口部６８の幅Ｗと雄ねじ山頂面６５の幅Ｖとの隙間Ｇが大きいことのもう一つの利点は、この隙間Ｇ分だけテーパ雄ねじ部６１を落とし込んでテーパ雌ねじ部６２の雌ねじ山６４のスタビングフランク面７２に預けた時、（管軸方向の隙間Ｇ×テーパＴ）／２の半径方向預け代が確保できるので、安定したねじ込みができることである。
【０００５】
以上の説明から判るように、スタビング性（テーパ雄ねじ部をテーパ雌ねじ部に差し込んだ後スムーズにねじ込みを可能とする性能）は、テーパ雄ねじ部６１をテーパ雌ねじ部６２に差し込んだ時、その位置からそのままねじ込みを開始することが可能な円周方向の範囲（θ）が広い程、またねじ込みを開始する時、雄ねじ山６３のスタビングフランク面７１を雌ねじ山６４のスタビングフランク面７２に預けている奥行きδ（前記半径方向預け代と同じ）が広い程、良好ということになる。そこで、このスタビング性を支配するθ、δに関して、従来のテーパねじ継手の形態について幾つかの例で説明する。
まず、ＡＰＩバットレス継手について説明すると、図２２（Ｂ）に示すように、第１にテーパ雄ねじ部６１の雄ねじ山６３のスタビングフランク面７１の角度、即ちスタビングフランク角ηを管軸Ｃに垂直な面から１０°傾けている。このスタビングフランク角ηの傾きが大きい程、填まり込みの隙間Ｇは広くなる。第２に、テーパ雄ねじ部６１の雄ねじ山６３のスタビングフランク面７１のコーナ部６９のＲ＝０．７６ｍｍをとり、さらにこの隙間Ｇは広がっている。その他、テーパ雄ねじ部６１が僅かに（直径で０．０３ｍｍ）テーパ雌ねじ部６２より痩せたねじになっていたり、雄、雌ねじ山頂面６５、６６とロードフランク面７３、７４とのコーナ部７５、７６のＲをとる（図２２（Ｂ）ではＲ＝０．２０ｍｍ）ことに依っても僅かに隙間Ｇが広がっている。この場合の全ての隙間の総和は約１．７５ｍｍと試算される。これを円周方向の範囲（θ）に換算すると、θ＝（３６０°×１．７５）／５．０８＝１２４°となる。一方、奥行き（δ）はδ＝１．７５／３２＝０．０５５ｍｍとなる。
【０００６】
また、ＡＲＭＣＯ社製のＳＥＡＬ−ＬＯＣＫ継手について説明すると、この特殊継手においては、第１に差し込み側のスタビングフランク角ηを管軸に垂直な面に対して４５°傾けている。第２に、雄、雌ねじ山頂面を管軸に平行とし、テーパ雄ねじ部をテーパ雌ねじ部に差し込む時、雄ねじ山と雌ねじ山同士が競りにくくしている。
さらに、ＶＥＴＣＯ−ＧＲＡＹ社製の特殊継手においては、４条ねじを適用することにより、一周３６０°の内、４ヶ所のねじ込み可能箇所ができるので、テーパ雄ねじ部をテーパ雌ねじ部に差し込み後、僅かの回転調整にて容易にねじ込みができる。なお、通常の１条ねじでは、ねじ込み可能箇所は１カ所である。
他の特殊継手として、テーパ雌ねじ部の入り口を長くする（スタビングガイドを設ける）ことにより、テーパ雄ねじ部をテーパ雌ねじ部に差し込む時斜めにならないようにしているものがある。
【０００７】
【発明が解決しようとする課題】
しかしながら、前記従来の管継手においては、未だ解決すべき以下のような問題があった。
１条ねじの形態のものでは、差し込み位置が必ずしもねじ込み開始位置とならず、ねじ込み位置を探るためテーパ雄ねじ部を回転しなければならないという問題があった。
一方、４条ねじを含む多条ねじの形態のものでは、ねじ込み可能箇所が条数だけ存在するので、調整の為の回転を少なくでき、これによって１条ねじに比べてかなりスタビング性は改善されるが、それでもいつも差し込み位置から直ちにねじ込むことは不可能である。
また、スタビングガイドを備えた形態のものでは、ねじの斜め差し込みによるかじりなどのトラブルは防げても、本質的に差し込み後直ちにねじ込みを行なうためのものではない。
【０００８】
本発明はこのような事情に鑑みてなされたもので、１条ねじのテーパ雄ねじ部をテーパ雌ねじ部に差し込んだ位置から、そのまま迅速かつ容易にねじ込むことが可能な管継手を提供することを目的とする。
【０００９】
【課題を解決するための手段】
前記目的に沿う請求項１記載の管継手は、管の先端部の外周面に１条ねじのテーパ雄ねじ部を形成したピンと、管の先端部の内周面に前記テーパ雄ねじ部に螺合するテーパ雌ねじ部を形成したボックスとをねじ込む管継手において、前記テーパ雄ねじ部の雄ねじ山のねじ山頂面と前記テーパ雌ねじ部の雌ねじ山のねじ山頂面は、角ねじ、台形ねじ又はバットレスねじのように所定の幅を有し、前記両ねじ山頂面を、管軸に平行な面に対してねじ列テーパ面と反対方向に傾斜させている。
請求項２記載の管継手は、管の先端部の外周面に１条ねじのテーパ雄ねじ部を形成したピンと、短管の両端部の内周面に前記テーパ雄ねじ部に螺合するテーパ雌ねじ部を形成したカップリングとをねじ込む管継手において、前記テーパ雄ねじ部の雄ねじ山のねじ山頂面と前記テーパ雌ねじ部の雌ねじ山のねじ山頂面は、角ねじ、台形ねじ又はバットレスねじのように所定の幅を有し、前記両ねじ山頂面を、管軸に平行な面に対してねじ列テーパ面と反対方向に傾斜させている。
【００１０】
請求項３記載の管継手は、管の先端部の外周面に１条ねじのテーパ雄ねじ部を形成したピンと、管の先端部の内周面に前記テーパ雄ねじ部に螺合するテーパ雌ねじ部を形成したボックスとをねじ込む管継手において、前記テーパ雄ねじ部の雄ねじ山のねじ山頂面と前記テーパ雌ねじ部の雌ねじ山のねじ山頂面は、角ねじ、台形ねじ又はバットレスねじのように所定の幅を有し、前記両ねじ山頂面の一部を管軸に平行な面に対してねじ列テーパ面と反対方向に傾斜させると共に、残りの該両ねじ山頂面を管軸に平行にしている。
請求項４記載の管継手は、管の先端部の外周面に１条ねじのテーパ雄ねじ部を形成したピンと、短管の両端部の内周面に前記テーパ雄ねじ部に螺合するテーパ雌ねじ部を形成したカップリングとをねじ込む管継手において、前記テーパ雄ねじ部の雄ねじ山のねじ山頂面と前記テーパ雌ねじ部の雌ねじ山のねじ山頂面は、角ねじ、台形ねじ又はバットレスねじのように所定の幅を有し、前記両ねじ山頂面の一部を管軸に平行な面に対してねじ列テーパ面と反対方向に傾斜させると共に、残りの該両ねじ山頂面を管軸に平行にしている。
【００１３】
請求項５記載の管継手は、管の先端部の外周面に１条ねじのテーパ雄ねじ部を形成したピンと、管の先端部の内周面に前記テーパ雄ねじ部に螺合するテーパ雌ねじ部を形成したボックスとをねじ込む管継手において、前記テーパ雄ねじ部を前記テーパ雌ねじ部に差し込む際、前記テーパ雄ねじ部の雄ねじ山のねじ山頂面に接する仮想テーパ面と前記テーパ雌ねじ部の雌ねじ山のねじ山頂面に接する仮想テーパ面とが一致する状態において、そのまま前記テーパ雄ねじ部を鉛直方向に下げると前記雄ねじ山のねじ山頂面が前記雌ねじ山のねじ山頂面に競ることなく、前記雄ねじ山のスタビングフランク面が前記雌ねじ山のスタビングフランク面に重なることが可能な元の雄ねじ列と雌ねじ列との位置関係を再現できるように、ねじ切り加工時に前記テーパ雄ねじ部及び前記テーパ雌ねじ部の円周方向に符合させる印を付けている。
請求項６記載の管継手は、管の先端部の外周面に１条ねじのテーパ雄ねじ部を形成したピンと、短管の両端部の内周面に前記テーパ雄ねじ部に螺合するテーパ雌ねじ部を形成したカップリングとをねじ込む管継手において、前記テーパ雄ねじ部を前記テーパ雌ねじ部に差し込む際、前記テーパ雄ねじ部の雄ねじ山のねじ山頂面に接する仮想テーパ面と前記テーパ雌ねじ部の雌ねじ山のねじ山頂面に接する仮想テーパ面とが一致する状態において、そのまま前記テーパ雄ねじ部を鉛直方向に下げると前記雄ねじ山のねじ山頂面が前記雌ねじ山のねじ山頂面に競ることなく、前記雄ねじ山のスタビングフランク面が前記雌ねじ山のスタビングフランク面に重なることが可能な元の雄ねじ列と雌ねじ列との位置関係を再現できるように、ねじ切り加工時に前記テーパ雄ねじ部及び前記テーパ雌ねじ部の円周方向に符合させる印を付けている。
【００１４】
本発明は、以下に説明する考え方に基づいてなされたものである。
テーパ雄ねじ部をテーパ雌ねじ部に真っ直ぐ差し込んだ時の態様には以下の３通りの場合がある。第１は、雄、雌ねじ山同士が競ってしまう時、第２は、雄、雌ねじ山が部分的に競ってしまう時、第３は、テーパ雄ねじ部の雄ねじ山のねじ山頂面がテーパ雌ねじ部の雌ねじ山の谷部に重なり引き続きテーパ雄ねじ部の雄ねじ山の側面（スタビングフランク面）が雌ねじ山の側面（スタビングフランク面）に着地するときである。
本発明は、テーパ雄ねじ部をテーパ雌ねじ部に差し込んだ後、直ちにねじ込みを可能にするために、テーパ雄ねじ部を差し込んだ時、常に前記第３の状態になるように雄、雌ねじ山の形状やねじ切り加工方法を工夫した次の３つの要素技術を採用している。
【００１５】
第１の要素技術は、図１に示すように、テーパ雄、雌ねじ部１１ａ、１２ａの雄、雌ねじ山１３ａ、１７ａのねじ山頂面１４ａ、２２ａを管軸Ｃに平行な面Ｄ（図１中破線）より僅かに雄、雌ねじ列の仮想テーパ面Ｔ（図１中２点鎖線）と逆方向のテーパ面Ｅ（図１中実線）とすることである。
第２の要素技術は、１リード内の多条ねじ山の一部を他のねじ山の高さより低くすることにより、スタビング時、雄、雌ねじ山同士が競り合う確率を小さくすることである。これは、ねじ山の低い部分を実質的には、１条ねじの谷部とみなすことに等しい。従って、２条ねじの場合は、テーパ雄ねじ部の雄ねじ山のねじ山頂面の幅の３倍の谷部の幅があることになり、スタビング時、雄ねじ山はテーパ雌ねじ部の谷部に容易に収まることになる。
【００１６】
第３の要素技術は、図２及び図３（Ａ）に示すように、テーパ雄ねじ部１１とテーパ雌ねじ部１２の軸方向のねじ山位置が常に第３の状態になるように、ねじ切り加工時にテーパ雄ねじ部１１の雄ねじ山１３のねじ山頂面１４の差し込み側のスタビングフランク面１５のコーナの座標（ｒ、Ｚm ）を予め決定しておき、それが通過するパイプ１６（又は管と呼ぶ）の円筒方向位置に印３１を付け、同時に、図２及び図３（Ｂ）に示すように、雄ねじ山１３のスタビングフランク面１５のコーナが填まり込みを開始する雌ねじ山１７の谷部１８が座標（ｒ、Ｚf ）になるようにパイプ１９（又は短管と呼ぶ）のテーパ雌ねじ部１２の先端２０の円周方向にも印２１を付け、差し込み時にそれらの印３１、２１同士が重なるようにテーパ雄、雌ねじ部１１、１２の円周方向位置を決め、管継手１０のねじ込み作業を行なう。
【００１７】
第１、第３の要素技術は、ねじの条数（例えば、２条ねじは１回転で２山ねじ込まれるねじ、即ちねじのリードがピッチの２倍あるねじ）に無関係に適用できることは自明である。ただし、多条ねじの場合、前記印の位置は円周方向に等分に条数だけ存在する点が通常の１条ねじと異なるが、第３の要素技術の考え方はそのまま適用できる。また、テーパねじ部を２段に分けたねじにおいても適用できることは言うまでもない（図１８（Ｃ）参照）。さらに、既述のスタビングガイドの考え（米国特許：４４０７５２７）と組み合わせることにより、テーパ雄ねじ部のテーパ雌ねじ部へのスタビングからねじ込みまでの一連の作業を省力化することを可能としている。
【００１８】
【発明の実施の形態】
続いて、添付した図面を参照しつつ、本発明を具体化した実施の形態につき説明し、本発明の理解に供する。
ここに、図１は本発明の一実施の形態に係る管継手が適用されるテーパねじ継手の差し込み位置の状態を説明する断面図、図２は同管継手が適用されるテーパねじ継手の差し込み適正範囲の状態を説明する断面図、図３は同管継手のねじ加工時の印位置を説明する斜視図、図４は同管継手が適用されるインテグラルタイプテーパねじ継手の形状を説明する断面図、図５は同管継手が適用されるカップリングタイプテーパねじ継手の形状を説明する断面図、図６は同管継手が適用されるテーパねじ継手の嵌合状態を説明する断面図、図７は同管継手が適用されるテーパねじ継手の差し込み位置の状態を説明する断面図、図８は同管継手が適用されるインテグラルタイプテーパねじ継手の形状を説明する断面図、図９は同管継手が適用されるカップリングタイプテーパねじ継手の形状を説明する断面図、図１０は本発明の一実施の形態に係る管継手が適用されるテーパねじ継手のスタビングフランク面の重なりが最大となる差し込み位置の状態を説明する断面図、図１１は同管継手が適用されるインテグラルタイプテーパねじ継手の形状を説明する断面図、図１２は同管継手が適用されるカップリングタイプテーパねじ継手の形状を説明する断面図、図１３は本発明の一実施の形態に係る管継手が適用されるテーパねじ継手のスタビングフランク面の重なりが最大となる差し込み位置の状態を説明する断面図、図１４は同管継手が適用されるインテグラルタイプテーパねじ継手の形状を説明する断面図、図１５は同管継手が適用されるカップリングタイプテーパねじ継手の形状を説明する断面図、図１６は同テーパねじ継手が３条の場合のねじ形状の断面図、図１７は同テーパねじ継手が４条の場合のねじ形状の断面図、図１８は同管継手が適用されるテーパねじ継手の形状を説明する断面図、図１９は同管継手の実施例の詳細寸法図、図２０は同詳細寸法図である。
【００１９】
図４は、本発明の一実施の形態に係る管継手１０ａである。管継手１０ａはインテグラルタイプ管継手であり、管１６ａの先端部の外周面にテーパ雄ねじ部１１ａを形成したピンと、管１６ａの増肉した先端部の内周面にテーパ雄ねじ部１１ａに螺合するテーパ雌ねじ部１２ａを形成したボックスとをねじ込む管継手において、テーパ雄ねじ部１１ａのバットレス形状雄ねじのねじ山頂面１４ａとテーパ雌ねじ部１２ａのバットレス形状雌ねじのねじ山頂面２２ａを、管軸Ｃに平行な面Ｄに対して、ねじ列テーパ面Ｔと反対方向の面Ｅに傾斜させたことを特徴とする。
【００２０】
図５は、管継手１０ａの変形例であり、管１６ａの先端部の外周面にテーパ雄ねじ部１１ａを形成したピンと、短管１９ａの両端部の内周面にテーパ雄ねじ部１１ａに螺合するテーパ雌ねじ部１２ａを形成したカップリングとをねじ込む管継手において、テーパ雄ねじ部１１ａのバットレス形状雄ねじのねじ山頂面１４ａとテーパ雌ねじ部１２ａのバットレス形状雌ねじのねじ山頂面２２ａを、管軸Ｃに平行な面Ｄに対して、ねじ列テーパ面Ｔと反対方向の面Ｅに傾斜させることを特徴とするカップリングタイプ管継手である。
【００２１】
図４及び図５のねじ部の拡大図を示す図１を参照しながら、工夫したねじ形状の機能を説明する。
図１に示す管継手１０ａは、テーパ雄ねじ部１１ａの雄ねじ山１３ａのスタビングフランク面１５ａとねじ山頂面１４ａとのコーナ部２４ａが、テーパ雌ねじ部１２ａの雌ねじ山１７ａのスタビングフランク面２５ａとねじ山頂面２２ａとのコーナ部２７ａに接した状態、即ち差し込み位置の状態を示している。
テーパ雄ねじ部１１ａとテーパ雌ねじ部１２ａは、図１の２点鎖線で示す仮想テーパ面（ねじ列テーパ面）Ｔを介して接することになり、この位置関係以外の位置では、テーパ雄ねじ部１１ａを仮想テーパ面Ｔ上のどこの位置にスライドさせても、テーパ雄ねじ部１１ａとテーパ雌ねじ部１２ａは接しないことになる。つまり、テーパ雄ねじ部１１ａは差し込み時仮想テーパ面Ｔを通過してテーパ雌ねじ部１２ａのスタビングフランク面２５ａに必ず着地できる。図１の位置関係の場合、テーパ雄ねじ部１１ａの雄ねじ山１３ａのコーナ部２４ａがテーパ雌ねじ部１２ａの雌ねじ山１７ａのコーナ部２７ａをすり抜ければ、コーナ部２４ａは管継手１０ａの管軸Ｃに平行な面Ｄ（破線で示す）に沿って下方に落下し、一つ下のスタビングフランク面２５ａの点２８に着地する。この時、雄ねじ山１３ａと雌ねじ山１７ａの重なりｗは最大となり、すり抜け難いが、ねじ嵌合は最も安定している。
【００２２】
このように雄ねじ山１３ａのスタビングフランク面１５ａが旨く雌ねじ山１７ａのスタビングフランク面２５ａに着地できるのは、図から明らかなように、角ねじ、台形ねじ又はバットレスねじのように所定の幅を有する雄ねじ山１３ａのねじ山頂面１４ａと雌ねじ山１７ａのねじ山頂面２２ａとが、差し込み時に競り合うことがないように、管軸Ｃに平行な面Ｄに対してねじテーパ角αと反対側にスタビング逃げ角βを設けて傾斜しているからである。理想的にはこれらねじ山頂面１４ａ、２２ａは管軸Ｃに平行でも競り合うことはないが、テーパ雄ねじ部１１ａの差し込み時には僅かな傾きがあり、ねじ継手自身にも不真円が存在するので、実際には雄、雌ねじ山１３ａ、１７ａ同士が競り合うことになる。スタビング逃げ角βは大きい方がねじ込み容易性の確保には安心であるが、反面大き過ぎると継手引張時に荷重を受け持つロードフランク面２３ａ、２６ａの高さｈが低くなり、テーパ雄ねじ部１１ａがテーパ雌ねじ部１２ａから抜け易くなる問題があるので、必要以上に大きくすることは適当でない。実験の結果、スタビング逃げ角βは最小限１°〜３°あれば実用上充分である。なお、図１中符号１６ａはパイプ、１８ａは谷部、１９ａはパイプ（又は短管）を示す。
【００２３】
図６は管継手１０ａのテーパ雄ねじ部１１ａとテーパ雌ねじ部１２ａとが締め付けを終了した状態、即ち嵌合状態を示している。
本実施の形態に係る管継手１０ａの場合のテーパねじ形状の特徴は、スタビングフランク面１５ａ、２５ａに比べロードフランク面２３ａ、２６ａの高さｈが低くなることである。このことは先に述べたテーパ雄ねじ部１１ａの抜けを惹起する可能性があるので、その抵抗を高めるために次の２つの方法を採用している。
第１は、図６に示すように、ロードフランク面２３ａ、２６ａを管軸Ｃに対する垂直面Ｖs より抜け難い方に角度γだけ傾けることである。
第２は、図７に示すように、雄、雌ねじ山１３ａ、１７ａのねじ山頂面１４ａ、２２ａの全面をスタビング逃げ角βとするのでなく、スタビングフランク面１５ａ、２５ａに近い側のみスタビング逃げ角βとし、残りのロードフランク面２３ａ、２６ａに近い側を管軸Ｃに平行とし、図７のねじ山頂部の黒塗り部分だけねじ山高さを稼ぐか、又はねじ山頂面１４ａ、２２ａの一方を全面スタビング逃げ角β又は部分的にスタビング逃げ角β、残りを管軸Ｃに平行とし、他方は全面管軸Ｃに平行なねじ山頂面とすることにより、ロードフランク面２３ａ、２６ａの高さｈ1 を高く維持している。
なお、ここで管軸Ｃに平行とは、正確に管軸Ｃとねじ山頂面が平行である場合の他、スタビング（差し込み）に支障にならない程度まで傾く場合も含まれる（以下同じ）。
【００２４】
図８及び図９は、それぞれ図７のねじ山形状を具備する本発明の一実施の形態を示すインテグラルタイプ及びカップリングタイプの管継手である。
【００２５】
図１０は、一山おきにねじ山高さを変えた、ねじリードＬ、ピッチｐ（Ｌ／２）の２条ねじからなるテーパ雄、雌ねじ部１１、１２において、雄ねじ山１３、１３ａ、雌ねじ山１７、１７ａが、それぞれのねじ山頂面１４、２２のコーナ部２４、２７が仮想テーパＴ線上で一致する差し込み位置の状態を示している。なお、雄ねじ山１３ａ及び雌ねじ山１７ａにおいて、雄ねじ山１３、雌ねじ山１７の各要素に対応するものには、図に添字ａを付けて説明している。
この状態から、テーパ雄ねじ部１１の雄ねじ山１３のねじ山頂面１４がテーパ雌ねじ部１２の雌ねじ山１７のねじ山頂面２２をすり抜ければ、コーナ部２４は管継手１０の管軸Ｃに平行な面Ｄ（破線で示す）に沿って落下し、一つ下の雌ねじ山１７ａを僅かにかわして、その下の雌ねじ山１７のスタビングフランク面２５の点２８に着地する。つまり、高さの低い雄ねじ山１３ａ、雌ねじ山１７ａを、高さの高い雄ねじ山１３が、高さの高い雌ねじ山１７に着地するのに妨げとならない程度に低くしておけばよい。こうして首尾よく、高さの高い雄ねじ山１３のスタビングフランク面１５が、高さの高い雌ねじ山１７のスタビングフランク面２５に重なれば、この時の雄ねじ山１３と雌ねじ山１７の重なりｗは最大となる。これは前記１条ねじの場合の２倍となり、着地の安定性はさらに向上する。
【００２６】
このように雄ねじ山１３のスタビングフランク面１５が旨く雌ねじ山１７のスタビングフランク面２５に着地できるのは、図から明らかなように、一つおきに低いねじ山を配置しているからである。なお、図１０中の符号１６はパイプ、符号１８は谷部、符号１９はパイプ、符号２６は雌ねじ山１７のロードフランク面を示す。
【００２７】
図１１及び図１２は、それぞれ図１０のねじ形状を具備する本発明の一実施の形態を示すインテグラルタイプ及びカップリングタイプの管継手である。
【００２８】
図１３は、一山おきにねじ山高さを変えた、ねじリードＬ、ピッチｐ（Ｌ／２）の２条ねじからなるテーパ雄、雌ねじ部１１、１２において、雄ねじ山１３、１３ａ、雌ねじ山１７、１７ａが、それぞれのねじ山頂面１４、２２の点と仮想テーパＴが接する状態で、尚かつ雄ねじ山１３のスタビングフランク面１５とねじ山頂面１４とのコーナ部２４が、テーパ雌ねじ部１２の雌ねじ山１７のスタビングフランク面２５とねじ山頂面２２とのコーナ部２７に接した状態、即ち差し込み位置の状態を示している。なお、雄ねじ山１３ａ及び雌ねじ山１７ａにおいて、雄ねじ山１３、雌ねじ山１７の各要素に対応するものには、図に添字ａを付けて説明している。
この状態から、テーパ雄ねじ部１１の雄ねじ山１３のコーナ部２４がテーパ雌ねじ部１２の雌ねじ山１７のコーナ部２７をすり抜ければ、コーナ部２４は管継手１０の管軸Ｃに平行な面Ｄ（破線で示す）に沿って落下し、一つ下の雌ねじ山１７ａを僅かにかわして、その下の雌ねじ山１７のスタビングフランク面２５の点２８に着地する。つまり、高さの低い雄ねじ山１３ａ、雌ねじ山１７ａを、高さの高い雄ねじ山１３が、高さの高い雌ねじ山１７に着地するのに妨げとならない程度に低くしておけばよい。こうして首尾よく、高さの高い雄ねじ山１３のスタビングフランク面１５が、高さの高い雌ねじ山１７のスタビングフランク面２５に重なれば、この時の雄ねじ山１３と雌ねじ山１７の重なりｗは最大となる。これは前記１条ねじの場合の２倍となり、着地の安定性はさらに向上する。
【００２９】
このように雄ねじ山１３のスタビングフランク面１５が旨く雌ねじ山１７のスタビングフランク面２５に着地できるのは、図から明らかなように、一つおきに低いねじ山を配置していることに加え、角ねじ又は台形ねじのように所定の幅を有する雄ねじ山１３のねじ山頂面１４と雌ねじ山１７のねじ山頂面２２とが、差し込み時に競り合うことがないように、管軸Ｃに平行な面Ｄに対してねじテーパ角αと反対側にスタビング逃げ角βを設けて傾斜しているからである。理想的にはこれらねじ山頂面１４、２２は管軸Ｃに平行（図１３の破線の補足線）でも競り合うことはないが、テーパ雄ねじ部１１の差し込み時には僅かな傾きがあるので、実際には雄、雌ねじ山１３、１７同士が競り合うこともあり得る。スタビング逃げ角βは大きい方がねじ込み容易性には優れるが、反面大き過ぎると継手引張時に荷重を受け持つロードフランク面２３、２３ａの高さｈが低くなり、テーパ雄ねじ部１１がテーパ雌ねじ部１２から抜け易くなる問題があるので、必要以上に大きくすることは適当でない。特に、雄ねじ山１３、１３ａ、雌ねじ山１７、１７ａの高さを低くすること自体でねじ山高さを犠牲にしているので、ねじ山頂面１４、２２の傾斜角はこの点も考慮して、必要ねじ高さを確保するように決定する。なお、図１３中符号１６はパイプ、１８は谷部、１９はパイプ、２６は雌ねじ山１７のロードフランク面を示す。
【００３０】
図１４及び図１５は、それぞれ図１３のねじ形状を具備する本発明の一実施の形態を示すインテグラルタイプ及びカップリングタイプの管継手である。
【００３１】
以上、２条ねじの例を詳しく述べてきたが、締め込みは条数が増す程速くなる。そこで、３条ねじ、４条ねじについても、ねじ山の高さの高低の付け方について触れておく。図１６（Ａ）は３条ねじで、高いねじ山を２つおき、即ち（条数−１）山おきに配置した場合を示す。
雄ねじ山１３ｃは、雌ねじ山１７ｃをすり抜けた状態で、雌ねじ山１７ｄに着地が見通せる位置にある。スタビングフランク面の重なりも広く取れ、ねじリードＬ内の広い範囲で安定して雌ねじ山１７ｄに着地可能である。しかし、嵌合した状態を想像すると、嵌合高さが図示のように狭くなる欠点を併せ持つことになる。なお、図１６（Ａ）中符号１３ｄは高さの高い雄ねじ山を示す。
【００３２】
図１６（Ｂ）は、この欠点を解消するため、スタビング位置と着地幅を犠牲にして、高さの高い雌ねじ山１７ｅ、１７ｆの中間の雌ねじ山１７ｇ、１７ｈの高さを高めにしたものである。雄ねじ山１３ｅ、１３ｆはそれぞれ雌ねじ山１７ｈ、１７ｆに着地可能である。なお、図１６（Ｂ）中符号１３ｇ、１３ｈも雄ねじ山を示す。
図１７（Ａ）は４条ねじで、高いねじ山を１つおきに配置した場合を示す。スタビング性（差し込みからねじ込みまでの作業性）及びねじ嵌合状況を２条ねじと同様とし、ねじ込み速さを２条ねじの倍にできる。雄ねじ山１３ｉ、１３ｋはそれぞれ雌ねじ山１７ｋ、１７ｎに着地可能である。
図１７（Ｂ）は４条ねじで、高いねじ山を３つおき、即ち（条数−１）山おきに配置した場合を示す。雄ねじ山１３ｐは雌ねじ山１７ｐをすり抜けた状態で、雌ねじ山１７ｔに着地が見通せる位置にある。図１６（Ａ）と同様、スタビング性は良好であるが、継手効率を犠牲にしている。ねじ切り工程で雄ねじ山と雌ねじ山のねじ列相対位置が、制御できるのであれば、図１６（Ｂ）及び図１７（Ａ）の場合でも、スタビング性には十分余裕があるので、図１６（Ａ）及び図１７（Ｂ）タイプのねじ山を高低配列したものより、図１６（Ｂ）及び図１７（Ａ）の方が継手効率も勘案するのであれば、適当である。
【００３３】
また、このように条数を増やしても、スタビング時、雄ねじ山の通り抜けをよくするために、高いねじ山のねじ山頂面にねじテーパと反対の傾斜を付ける考え方は、２条ねじの場合と同様である。
既に、図２２（Ａ）に関して、現行のＡＰＩバットレス継手でも、差し込み位置を適切に選べば、差し込み後ただちに締め込むことが可能であることを説明した。要点は、図２２（Ａ）の位置から、雄ねじ山６３のスタビングフランク面７１のコーナＲが、テーパ雌ねじ部６２のスタビングフランク面７２のコーナＲに接するところまでならどの位置からでも、テーパ雄ねじ部６１を鉛直に落下すれば、雄ねじのスタビングフランク面７１は雌ねじのスタビングフランク面７２に載ることが出来るので、テーパ雄ねじ部６１はテーパ雌ねじ部６２に嵌まり込むことができる。
【００３４】
問題は、いかにすれば、雄ねじと雌ねじの位置関係を図２２（Ａ）のように出来るかである。
本実施の形態では、前記の填まり込みが可能な範囲の中心に、雄ねじ列と雌ねじ列が対応するようにねじ切り加工時に、ピンとカップリング（又はボックス）外表面に印を付けることにし、差し込み時にその印のある所を合わせれば、ピンとボックスが必ずねじ込みに好適な位置にくるようにした。
つまり、図２に示す仮想テーパ面Ｔ上の中央の○印を雄ねじ切り刃物２８、雌
ねじ切り刃物２９の基準位置と考えれば、図３（Ａ）、（Ｂ）にそれぞれ示すように、雄ねじ切りパスでは、（ｒ、Ｚm ）を通過するように、一方、雌ねじ切りパスでは、（ｒ、Ｚf ）を通過するように、ねじ切り開始時の雄ねじ切り刃物２８、雌ねじ切り刃物２９とパイプ１６、１９との関係を設定し、その時の刃物運動面Ｆm 、Ｆf がそれぞれパイプ１６、１９と交わるパイプ１６、１９の周方向位置に印３１、２１を付けておく。こうすることで、印３１、２１の付いたテーパ雄ねじ部１１とテーパ雌ねじ部１２をその印３１、２１の位置を円周方向に一致させて差し込めば、必ず図２に示す位置関係、即ち雄、雌ねじ山１３、１７のねじ山頂面１４、２２が競ることなく、雄ねじ山１３のスタビングフランク面１５が雌ねじ山１７のスタビングフランク面２５に重なることが可能な元の雄ねじ列と雌ねじ列との位置関係を再現でき、円滑なテーパ雄ねじ部１１の差し込み及びそれに続くねじ込みが可能となる。なお、図２中符号２３、２６はロードフランク面、符号３０はテーパ雄ねじ部１１の先端を示している。
【００３５】
本発明は前記実施の形態以外にも、図１８に示す管継手形状に適用可能である。図１８（Ａ）は締結ねじのみを備えた管継手１０ｂ、図１８（Ｂ）はねじ嵌合部の先端部に金属シール部を具備する管継手１０ｃ、図１８（Ｃ）は（Ａ）又は（Ｂ）の一様テーパねじ部を２段に分けた管継手１０ｄである。なお、図１８中符号１１ｂ〜１１ｄはテーパ雄ねじ部を、符号１２ｂ〜１２ｄはテーパ雌ねじ部を表している。
【００３６】
【実施例】
続いて、前記実施の形態に係る管継手の実施例について、図１９を参照しながら説明する。図１９は、７インチのＡＰＩバットレス継手を原形とし、前記実施の形態に係る管継手を基にスタビング性を改良したものである。なお、図１９（Ａ）は管継手の嵌合状態での取り合い寸法を示す断面図である。
ＡＰＩバットレス継手と異なるねじ諸元は、ピン、ボックスそれぞれの雄、雌ねじ山のねじ山頂面が管軸Ｃに対してねじ列テーパ面ＰＴ、ＢＴと反対側に３°傾斜し、ロードフランク面が管軸Ｃに垂直な面に対して、ＡＰＩバットレス継手の場合とは反対方向に３°傾斜している点である。
【００３７】
また、スタビング時のピン、ボックスの雄、雌ねじ山の相対位置を指定する目的で、図１９（Ｃ）に示すように、テーパ雄ねじ部では、半径ｒ＝１７５．０５７ｍｍ、テーパ雄ねじ部の先端３０からＺm ＝５．９ｍｍの座標が図中Ｐ点（雄ねじ山のねじ山頂面とスタビングフランク面との交点、即ちＲ加工の無い場合を示す）に一致するように雄ねじ切り刃物２８の位置を定め、Ｐ点がねじ列テーパ面（１点鎖線ＰＴ）と交わる周方向位置に印３１をマークする（図２及び図３参照）。同様に図１９（Ｂ）に示すように、テーパ雌ねじ部では、半径ｒ＝１７５．０５７ｍｍ、テーパ雌ねじ部の先端２０からＺf ＝４５．３１ｍｍの座標が図中Ｂ点（雌ねじ山のねじ山頂面とスタビングフランク面との交点、即ちＲ加工の無い場合を示す）に一致するように雌ねじ切り刃物２９の位置を定め、Ｂ点がねじテーパ面（２点鎖線ＢＴ）と交わる周方向位置に印２１をマークする（図２及び図３参照）。
【００３８】
このような要領でねじ継手加工と、マーキングを行い、印３１、２１の位置を符合させるように鉛直方向にテーパ雄ねじ部をテーパ雌ねじ部に差し込んで、その状態からそのままねじ込みが可能かどうか試した。その結果、管軸Ｃが傾かないようにテーパ雄ねじ部をテーパ雌ねじ部に注意深く挿入すれば、マーキング位置はもちろん、３６０°のどの位置に差し込んでも、そのままねじ込むことが可能であることを確認した。
また、実用上問題なかったが、円周方向の一箇所だけ、差し込み後さらに１ピッチ分だけ落下する現象が観察された。そこはピン、ボックスの相対位置関係が印３１と印２１が丁度１８０°反対になる所であった。つまり、ピンとボックスが丁度図１の位置にあったと推察される。
【００３９】
上記と嵌合時の寸法（図１９（Ａ））を変えずに、ねじ形状のみ１条ねじからねじ山高低案を適用した２条ねじの場合を図２０（Ａは雌ねじ、Ｂは雄ねじ）に示す。この場合も、上記同様３６０°どの位置に差し込んでもそのままねじ込むことが可能であることを確認した。
また、軸芯ずれをなくすために、テーパ雌ねじ部の先端２０に２００ｍｍの円筒をスタビングガイドとして溶接して、同じ作業を実施したところ、芯合わせに神経を使うことなくスタビング、ねじ込みの連続作業が可能であることも確認できた。
なお、前記実施例において、ねじ山のクレストとスタビングフランク面の交わるコーナ部を、例えば焼き付き防止の観点から丸くすることもできる。
【００４０】
【発明の効果】
請求項１及び請求項２記載の管継手においては、テーパ雄ねじ部の雄ねじ山のねじ山頂面とテーパ雌ねじ部の雌ねじ山のねじ山頂面は、角ねじ、台形ねじ又はバットレスねじのように所定の幅を有し、両ねじ山頂面を、管軸に平行な面に対してねじ列テーパ面と反対方向に傾斜させているので、テーパ雄ねじ部を３６０°のどの位置で差し込んでも差し込み及びそれに続くねじ込みの連続作業が可能である。
請求項３及び請求項４記載の管継手においては、テーパ雄ねじ部の雄ねじ山のねじ山頂面とテーパ雌ねじ部の雌ねじ山のねじ山頂面は、角ねじ、台形ねじ又はバットレスねじのように所定の幅を有し、両ねじ山頂面の一部を管軸に平行な面に対してねじ列テーパ面と反対方向に傾斜させると共に、残りの両ねじ山頂面を管軸に平行にしているので、ロードフランク面の高さを大きく保つことができ、抜け難いねじ継手形状にできる。
【００４２】
請求項５及び請求項６記載の管継手においては、テーパ雄ねじ部をテーパ雌ねじ部に差し込む際、テーパ雄ねじ部の雄ねじ山のねじ山頂面に接する仮想テーパ面とテーパ雌ねじ部の雌ねじ山のねじ山頂面に接する仮想テーパ面とが一致する状態において、そのままテーパ雄ねじ部を鉛直方向に下げると雄ねじ山のねじ山頂面が雌ねじ山のねじ山頂面に競ることなく、雄ねじ山のスタビングフランク面が雌ねじ山のスタビングフランク面に重なることが可能な元の雄ねじ列と雌ねじ列との位置関係を再現できるように、ねじ切り加工時にテーパ雄ねじ部及びテーパ雌ねじ部の円周方向に符合させる印を付けているので、円滑なテーパ雄ねじ部の差し込み及びそれに続くねじ込みの連続作業が可能となる。
【図面の簡単な説明】
【図１】本発明の一実施の形態に係る管継手が適用されるテーパねじ継手の差し込み位置の状態を説明する断面図である。
【図２】同管継手が適用されるテーパねじ継手の差し込み適正範囲の状態を説明する断面図である。
【図３】同管継手のねじ加工時の印位置を説明する斜視図である。
【図４】同管継手が適用されるインテグラルタイプテーパねじ継手の形状を説明する断面図である。
【図５】同管継手が適用されるカップリングタイプテーパねじ継手の形状を説明する断面図である。
【図６】同管継手が適用されるテーパねじ継手の嵌合状態を説明する断面図である。
【図７】同管継手が適用されるテーパねじ継手の差し込み位置の状態を説明する断面図である。
【図８】同管継手が適用されるインテグラルタイプテーパねじ継手の形状を説明する断面図である。
【図９】同管継手が適用されるカップリングタイプテーパねじ継手の形状を説明する断面図である。
【図１０】本発明の一実施の形態に係る管継手が適用されるテーパねじ継手のスタビングフランク面の重なりが最大となる差し込み位置の状態を説明する断面図である。
【図１１】同管継手が適用されるインテグラルタイプテーパねじ継手の形状を説明する断面図である。
【図１２】同管継手が適用されるカップリングタイプテーパねじ継手の形状を説明する断面図である。
【図１３】本発明の一実施の形態に係る管継手が適用されるテーパねじ継手のスタビングフランク面の重なりが最大となる差し込み位置の状態を説明する断面図である。
【図１４】同管継手が適用されるインテグラルタイプテーパねじ継手の形状を説明する断面図である。
【図１５】同管継手が適用されるカップリングタイプテーパねじ継手の形状を説明する断面図である。
【図１６】同テーパねじ継手が３条の場合のねじ形状の断面図である。
【図１７】同テーパねじ継手が４条の場合のねじ形状の断面図である。
【図１８】同管継手が適用されるテーパねじ継手の形状を説明する断面図である。
【図１９】同管継手の実施例の詳細寸法図である。
【図２０】同詳細寸法図である。
【図２１】（Ａ）、（Ｂ）はそれぞれ従来例に係る管用テーパ角ねじを有する管継手のねじ込み開始の状況を説明する断面図及びその拡大図である。
【図２２】（Ａ）、（Ｂ）はそれぞれＡＰＩバットレスねじ継手のねじ込み開始の状況を説明する断面図及びねじ形状の詳細図である。
【符号の説明】
１０：管継手、１０ａ〜１０ｄ：管継手、１１：テーパ雄ねじ部、１１ａ〜１１ｄ：テーパ雄ねじ部、１２：テーパ雌ねじ部、１２ａ〜１２ｄ：テーパ雌ねじ部、１３：雄ねじ山、１３ａ：雄ねじ山、１４：ねじ山頂面、１４ａ：ねじ山頂面、１５：スタビングフランク面、１５ａ：スタビングフランク面、１６：パイプ、１６ａ：パイプ、１７：雌ねじ山、１７ａ：雌ねじ山、１８：谷部、１８ａ：谷部、１９：パイプ、１９ａ：パイプ、２０：先端、２１：印、２２：ねじ山頂面、２２ａ：ねじ山頂面、２３：ロードフランク面、２３ａ：ロードフランク面、２４：コーナ部、２４ａ：コーナ部、２５：スタビングフランク面、２５ａ：スタビングフランク面、２６：ロードフランク面、２６ａ：ロードフランク面、２７：コーナ部、２７ａ：コーナ部、２８：雄ねじ切り刃物、２９：雌ねじ切り刃物、３０：先端、３１：印[0001]
BACKGROUND OF THE INVENTION
The present invention improves the workability when a taper male threaded portion of a pin is inserted vertically into a taper female threaded portion of a box or coupling in a taper threaded joint such as an oil well pipe and a civil engineering pile pipe, and subsequently rotated and tightened. Relates to possible pipe fittings.
[0002]
[Prior art]
Conventionally, as pipe joints such as oil well pipes and civil engineering pile pipes, as shown in FIG. 21, the taper male thread portion 52 of the pin 51 of the pipe 50 and the taper female thread part 55 of the box 54 of the short pipe 53 are fitted. Threaded joints (including trapezoidal screws and buttress screws) are used. The state of the screwing start of this tapered angle threaded joint for pipes is shown in an enlarged view.
In order to easily understand the stubbing property of the tapered angle threaded joint for pipes, the male and female thread threads 56 and 57 of the tapered male thread part 52 and the tapered female thread part 55 have the same shape. Parallel to the taper surface Tf. The fitting cross-sectional view shown in the figure shows exactly where the male thread 56 is about to bite into the female thread 57. That is, the taper surface connecting the male thread crest surface 58 of the taper male screw portion 52 and the taper surface connecting the female screw crest surface 59 of the taper female screw portion 55 are exactly the same, and the male screw thread 56 is the valley 60 of the female screw thread 57. The circumferential direction position of the taper male screw part 52 and the circumferential direction position of the taper female thread part 55 are made uniform so as to be located in FIG. As is apparent from the drawing, it is impossible to screw the tapered male threaded portion 52 into the tapered female threaded portion 55 in this state.
[0003]
Here, as to the stubbing property of the tapered angle threaded joint for pipes, as shown in FIG. 22 (B), the case of an API buttress threaded joint widely used as an oil well pipe thread is taken as an example, and the tapered male threaded portion 61 is a tapered female thread. How the male and female screw threads 63 and 64 are screwed in after being inserted into the part 62 will be described.
API buttress screw element has taper T = 1/16 (or 62.5 mm / m, rate of change with diameter), pitch P = 0.08 mm, thread height H = 1.575 mm, stubbing flank angle η = 10 ° , The load flank angle γ = 3 °, the straight portions of the male and female thread crest surfaces 65 and 66 are parallel to the tapered surface Tp (ie, the pitch line), and the corner R of the male and female thread crest surfaces 65 and 66 is 0.76 mm or It is characterized by 0.20 mm.
FIG. 22A shows a situation in which the tapered male screw portion 61 and the tapered female screw portion 62 are fitted in the most convenient circumferential direction for screwing. Unlike the case of the taper angle threaded joint for pipes, the opening 68 of the valley 67 of the taper female thread 62 is wider than the male thread crest surface 65 of the male thread 63 and the difference is widened by taking the corner R. When the tapered male screw portion 61 is dropped vertically from this state, the corner portion 69 of the male screw thread 63 of the taper male screw portion 61 may be slightly placed on the corner portion 70 of the female screw thread 64 of the tapered female screw portion 62. If the taper male screw portion 61 is turned from this state, the taper male screw portion 61 is fitted along the spiral.
[0004]
Further, in order for the tapered male screw portion 61 to be fitted into the tapered female screw portion 62 in this way, the relative positions of the male screw row and the female screw row do not necessarily have to be as shown in FIG. Even at a position where the taper male screw portion 61 is shifted downward along the taper from the position of FIG. 22A until the corner R of the bing flank surface 71 contacts the corner R of the stubbing flank surface 72 of the taper female screw portion 62, The tapered male thread portion 61 can be fitted into the tapered female thread portion 62. That is, when the taper male screw portion 61 is inserted into the taper female screw portion 62 by an amount corresponding to the circumferential angle corresponding to this deviation, a margin can be given to the circumferential range for screwing in well.
In a normal insertion and screwing start operation, the tapered male screw portion 61 is inserted into the tapered female screw portion 62, and the male screw thread 63 of the tapered male screw portion 61 is moved to the female screw thread 64 of the tapered female screw portion 62 until the circumferential position is reached. The taper male screw part 61 is rotated. At this time, since the male thread 63 and the female thread 64 are not yet engaged with each other, if the axes of the tapered male and female thread portions 61 and 62 are not aligned, galling may occur. For steel pipes with large diameters, the screw-in position search is difficult if the rotation angle is large. Accordingly, the wider the range of the circumferential position in which the male thread 63 and the female thread 64 can be engaged, the smaller the rotation angle to be rotated to an appropriate place, and it can be said that the taper screw joint has good stubbing performance. Further, another advantage of the large gap G between the width W of the opening 68 of the valley 67 of the tapered female thread 62 and the width V of the male thread crest surface 65 is that the tapered male thread 61 is dropped by this gap G. In the case of depositing on the stubbing flank surface 72 of the female thread 64 of the taper female thread portion 62, it is possible to secure a margin in the radial direction of (gap G in the tube axis direction × taper T) / 2, which enables stable screwing. .
[0005]
As can be seen from the above description, the stubbing property (the performance that enables smooth screwing after the taper male screw portion is inserted into the taper female screw portion) is determined from the position when the taper male screw portion 61 is inserted into the taper female screw portion 62. As the circumferential range (θ) in which screwing can be started is wider, and when screwing is started, the stubbing flank surface 71 of the male screw thread 63 is deposited on the stubbing flank surface 72 of the female screw thread 64. The wider the depth δ (same as the radial deposit), the better. Therefore, with respect to θ and δ that govern this stubbing property, the configuration of a conventional tapered screw joint will be described with some examples.
First, the API buttress joint will be described. First, as shown in FIG. 22B, the angle of the stubbing flank surface 71 of the male thread 63 of the tapered male threaded portion 61, that is, the stubbing flank angle η is defined as the tube axis C. It is tilted 10 ° from the vertical plane. The larger the inclination of the stubbing flank angle η, the wider the gap G for filling. Secondly, R = 0.76 mm of the corner portion 69 of the stubbing flank 71 of the male thread 63 of the taper male thread portion 61 is taken, and the gap G further increases. In addition, the taper male screw portion 61 is slightly thinner (0.03 mm in diameter) than the taper female screw portion 62, or the corner portion 75 of the male and female screw crest surfaces 65 and 66 and the load flank surfaces 73 and 74, Even if R of 76 is taken (R = 0.20 mm in FIG. 22B), the gap G is slightly widened. In this case, the total sum of all the gaps is estimated to be about 1.75 mm. When this is converted into a circumferential range (θ), θ = (360 ° × 1.75) /5.08=124°. On the other hand, the depth (δ) is δ = 1.75 / 32 = 0.555 mm.
[0006]
Further, the SEAL-LOCK joint manufactured by ARMCO will be described. In this special joint, first, the stubbing flank angle η on the insertion side is inclined by 45 ° with respect to the plane perpendicular to the tube axis. Secondly, when the male and female thread crests are parallel to the tube axis and the tapered male thread part is inserted into the tapered female thread part, the male thread and female thread are less likely to compete.
Furthermore, in the special joint made by VETCO-GRAY, by applying 4 threads, there are 4 places where screwing is possible within 360 ° of the circumference. After inserting the taper male thread part into the taper female thread part, Can be screwed in easily by adjusting the rotation. In addition, in a normal single thread screw, the screwable place is one place.
As another special joint, there is one that lengthens the entrance of the taper female thread part (provides a stubbing guide) so that the taper male thread part is not inclined when inserted into the taper female thread part.
[0007]
[Problems to be solved by the invention]
However, the conventional pipe joint still has the following problems to be solved.
In the case of the single thread type, there is a problem that the insertion position is not necessarily the screw start position, and the tapered male thread portion must be rotated in order to find the screw position.
On the other hand, in the form of a multi-threaded screw including four-threaded screws, there are as many threadable locations as there are threads, so that the rotation for adjustment can be reduced, which significantly improves the stubbing performance compared to single-threaded screws. However, it is still impossible to screw in immediately from the insertion position.
Further, in the configuration provided with the stubbing guide, troubles such as galling due to the diagonal insertion of the screw can be prevented, but it is not essentially for screwing in immediately after insertion.
[0008]
The present invention has been made in view of such circumstances, Taper male thread part of single thread It is an object of the present invention to provide a pipe joint that can be quickly and easily screwed in from a position inserted into a taper female thread portion.
[0009]
[Means for Solving the Problems]
The pipe joint according to claim 1, which meets the purpose, is provided on the outer peripheral surface of the tip portion of the pipe. Single thread In a pipe joint for screwing a pin formed with a tapered male threaded portion and a box formed with a tapered female threaded portion to be screwed onto the inner peripheral surface of the distal end portion of the tube into the tapered male threaded portion, the top surface of the threaded male thread of the tapered male threaded portion And the thread top surface of the female thread of the taper female thread portion has a predetermined width such as a square screw, trapezoidal screw, or buttress screw, and both the thread top surfaces are threaded with respect to a surface parallel to the tube axis. It is inclined in the opposite direction to the tapered surface.
The pipe joint according to claim 2 is provided on the outer peripheral surface of the tip portion of the pipe. Single thread In a pipe joint for screwing a pin formed with a tapered male threaded portion and a coupling formed with a tapered female threaded portion to be screwed into the inner circumferential surface of both ends of the short pipe into the tapered male threaded portion, the thread of the male thread of the tapered male threaded portion The crest surface and the crest surface of the female thread of the tapered female thread portion have a predetermined width such as a square screw, a trapezoidal screw, or a buttress screw, and both the crest surfaces are parallel to the surface parallel to the tube axis. It is inclined in the direction opposite to the thread row taper surface.
[0010]
The pipe joint according to claim 3 is provided on the outer peripheral surface of the tip portion of the pipe. Single thread In a pipe joint for screwing a pin formed with a tapered male threaded portion and a box formed with a tapered female threaded portion to be screwed onto the inner peripheral surface of the distal end portion of the tube into the tapered male threaded portion, the top surface of the threaded male thread of the tapered male threaded portion And the thread top surface of the female thread of the taper female thread portion has a predetermined width such as a square thread, trapezoidal screw or buttress thread, and a part of both thread top surfaces is parallel to the surface parallel to the tube axis. It is inclined in the direction opposite to the thread row taper surface, and the remaining thread top surfaces are parallel to the tube axis.
The pipe joint according to claim 4 is provided on the outer peripheral surface of the tip portion of the pipe. Single thread In a pipe joint for screwing a pin formed with a tapered male threaded portion and a coupling formed with a tapered female threaded portion to be screwed into the inner surface of both ends of the short pipe into the tapered male threaded portion, the thread of the male thread of the tapered male threaded portion The crest surface and the crest surface of the female thread of the tapered female thread portion have a predetermined width such as a square screw, a trapezoidal screw, or a buttress screw, and a part of both crest surfaces is parallel to the pipe axis. On the other hand, it is inclined in the opposite direction to the thread row taper surface, and the remaining thread crest surfaces are parallel to the tube axis.
[0013]
Claim 5 The described pipe joint is provided on the outer peripheral surface of the pipe tip. Single thread In a pipe joint for screwing a pin having a tapered male threaded portion and a box having a tapered female threaded portion screwed into the inner peripheral surface of the distal end of the tube into the tapered male threaded portion, the tapered male threaded portion is inserted into the tapered female threaded portion. In the state where the virtual taper surface in contact with the thread top surface of the male thread of the taper male thread portion and the virtual taper surface in contact with the thread top surface of the female thread of the taper female thread portion coincide, The original male thread row in which the male screw thread stubbing flank surface can overlap the female thread thread stubbing flank face without competing with the female thread thread top surface. In order to reproduce the positional relationship between the taper and the female thread row, the taper male thread part and the taper female thread part are marked in the circumferential direction during threading. It is marked to be.
Claim 6 The described pipe joint is provided on the outer peripheral surface of the pipe tip. Single thread In a pipe joint in which a pin formed with a tapered male screw portion and a coupling formed with a tapered female screw portion screwed into the tapered male screw portion on inner peripheral surfaces of both ends of the short pipe are screwed, the tapered male screw portion is replaced with the tapered female screw portion. In the state where the virtual taper surface in contact with the screw thread top surface of the male screw thread of the taper male screw part and the virtual taper surface in contact with the screw thread top surface of the female screw thread of the taper female screw part coincide, When lowered in the vertical direction, the external thread thread top surface does not compete with the internal thread thread top surface, and the external thread stubbing flank surface can overlap the internal thread thread stubbing flank surface. Circumferential direction of the taper male screw portion and the taper female screw portion at the time of threading so that the positional relationship between the male screw row and the female screw row can be reproduced. It is marked to sign in.
[0014]
The present invention has been made based on the concept described below.
There are the following three cases when the taper male screw portion is inserted straight into the taper female screw portion. The first is when the male and female threads are competing with each other, the second is when the male and female threads are partially competing, and the third is the thread top surface of the male thread of the tapered male thread is the tapered female thread This is when the side surface (stubbing flank surface) of the male thread portion of the tapered male thread portion lands on the side surface (stubbing flank surface) of the female thread thread.
In order to enable the screwing immediately after the taper male screw portion is inserted into the taper female screw portion, the shape of the male and female screw threads is such that the third state is always obtained when the taper male screw portion is inserted. The following three elemental technologies that employ a threading method have been adopted.
[0015]
As shown in FIG. 1, the first elemental technology is a surface D parallel to the tube axis C (see FIG. 1), with the taper male, the male threaded portions 11a, 12a male, and the female thread top surfaces 14a, 22a of the female thread 13a, 17a. The taper surface E (solid line in FIG. 1) is opposite to the virtual taper surface T (two-dot chain line in FIG. 1) of the male and female screw trains slightly from the broken line).
The second elemental technology is to reduce the probability that the male and female threads compete with each other during stubbing by making a part of the multiple thread threads in one lead lower than the height of the other threads. This is substantially equivalent to considering the low thread portion as a single thread thread valley. Therefore, in the case of double thread, there is a trough width that is three times the width of the thread top surface of the male thread of the taper male thread part. During stubbing, the male thread is easily located in the trough of the taper female thread part. Will fit.
[0016]
As shown in FIG. 2 and FIG. 3 (A), the third elemental technology is used at the time of threading so that the axial thread positions of the tapered male threaded portion 11 and the tapered female threaded portion 12 are always in the third state. The coordinates (r, Zm) of the corner of the stubbing flank surface 15 on the insertion side of the thread top surface 14 of the male thread 13 of the taper male thread portion 11 are determined in advance, and the pipe 16 (or tube) through which the corner passes is determined. At the same time, as shown in FIG. 2 and FIG. 3 (B), at the cylindrical direction position of the male screw thread 13, the corner of the stubbing flank surface 15 of the male screw thread 13 starts to fill and the valley portion 18 of the female thread thread 17 starts. Is also marked in the circumferential direction of the tip 20 of the taper female threaded portion 12 of the pipe 19 (or short pipe) so that becomes the coordinates (r, Zf), and these marks 31, 21 overlap when inserted. Taper male, female thread The circumferential positions of the portions 11 and 12 are determined, and the pipe joint 10 is screwed.
[0017]
It is obvious that the first and third elemental technologies can be applied regardless of the number of threads of the screw (for example, a double thread is a screw that is screwed twice in one rotation, that is, a screw having a screw lead twice the pitch). is there. However, in the case of a multi-threaded screw, the position of the mark is different from a normal single-threaded screw in that the number of marks is equally divided in the circumferential direction, but the concept of the third element technology can be applied as it is. Needless to say, the present invention can also be applied to a screw in which the taper screw portion is divided into two stages (see FIG. 18C). Furthermore, by combining with the above-described idea of the stubbing guide (US Pat. No. 4,407,527), it is possible to save labor in a series of operations from stubbing to screwing of the tapered male threaded portion into the tapered female threaded portion.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
FIG. 1 is a cross-sectional view for explaining a state of an insertion position of a taper threaded joint to which a pipe joint according to an embodiment of the present invention is applied, and FIG. 2 is an insertion of a taper threaded joint to which the pipe joint is applied. FIG. 3 is a perspective view for explaining a mark position during threading of the pipe joint, and FIG. 4 is a cross section for explaining the shape of an integral type taper threaded joint to which the pipe joint is applied. 5 is a cross-sectional view illustrating the shape of a coupling type taper threaded joint to which the pipe joint is applied. FIG. 6 is a cross-sectional view illustrating a fitting state of the taper threaded joint to which the pipe joint is applied. 7 is a cross-sectional view for explaining the state of the insertion position of the taper screw joint to which the pipe joint is applied, FIG. 8 is a cross-sectional view for explaining the shape of the integral type taper screw joint to which the pipe joint is applied, and FIG. The bracket to which the fitting is applied Sectional drawing explaining the shape of a ring type taper threaded joint, FIG. 10 shows the state of the insertion position where the overlap of the stubbing flank surface of the taper threaded joint to which the pipe joint which concerns on one embodiment of this invention is applied becomes the maximum. FIG. 11 is a sectional view for explaining the shape of an integral type taper threaded joint to which the pipe joint is applied, and FIG. 12 is a sectional view for explaining the shape of a coupling type taper threaded joint to which the pipe joint is applied. FIG. 13 is a cross-sectional view for explaining the state of the insertion position where the overlap of the stubbing flank surfaces of the taper threaded joint to which the pipe joint according to one embodiment of the present invention is applied is maximized, and FIG. 14 is the same pipe joint. FIG. 15 illustrates the shape of a coupling type taper threaded joint to which the pipe joint is applied. 16 is a cross-sectional view of a screw shape when the taper threaded joint has three threads, FIG. 17 is a cross-sectional view of a screw shape when the taper threaded joint has four threads, and FIG. 18 applies the pipe joint. FIG. 19 is a detailed dimensional view of an embodiment of the pipe joint, and FIG. 20 is a detailed dimensional view of the tapered threaded joint.
[0019]
FIG. 4 shows a pipe joint 10a according to an embodiment of the present invention. The pipe joint 10a is an integral type pipe joint, and is screwed into the taper male screw part 11a on the pin formed with the taper male thread part 11a on the outer peripheral surface of the tip part of the pipe 16a and the inner peripheral surface of the thickened tip part of the pipe 16a. In the pipe joint for screwing the box formed with the tapered female thread portion 12a, the buttress-shaped male thread top surface 14a of the tapered male thread portion 11a and the buttress-shaped female thread top surface 22a of the tapered female thread portion 12a are parallel to the tube axis C. It is characterized in that it is inclined with respect to the surface D to a surface E in a direction opposite to the thread row tapered surface T.
[0020]
FIG. 5 shows a modified example of the pipe joint 10a, and a pin having a tapered male threaded portion 11a formed on the outer peripheral surface of the distal end portion of the pipe 16a and a tapered male threaded portion 11a threaded on the inner peripheral surfaces of both end portions of the short pipe 19a. In the pipe joint into which the coupling formed with the taper female thread portion 12a is screwed, the buttress-shaped male thread top surface 14a of the taper male thread portion 11a and the buttress-shaped female thread top surface 22a of the taper female thread portion 12a are parallel to the tube axis C. The coupling type pipe joint is characterized in that it is inclined to a surface E opposite to the thread row tapered surface T with respect to the smooth surface D.
[0021]
The function of the devised screw shape will be described with reference to FIG. 1 showing an enlarged view of the screw portion of FIGS. 4 and 5.
The pipe joint 10a shown in FIG. 1 has a corner portion 24a between a stubbing flank surface 15a of a male thread 13a of a tapered male thread portion 11a and a thread top surface 14a, and a stubbing flank surface 25a of a female thread 17a of a tapered female thread portion 12a. The state which contact | connected the corner part 27a with the screw thread top surface 22a, ie, the state of the insertion position, is shown.
The taper male screw portion 11a and the taper female screw portion 12a are in contact with each other via a virtual taper surface (thread row taper surface) T indicated by a two-dot chain line in FIG. The taper male screw portion 11a and the taper female screw portion 12a are not in contact with each other regardless of the position on the virtual taper surface T. That is, the taper male screw portion 11a can always land on the stubbing flank surface 25a of the taper female screw portion 12a through the virtual taper surface T when inserted. In the case of the positional relationship of FIG. 1, if the corner portion 24a of the male thread 13a of the taper male thread portion 11a passes through the corner portion 27a of the female thread 17a of the taper female screw portion 12a, the corner portion 24a moves to the tube axis C of the pipe joint 10a. It falls downward along a parallel surface D (shown by a broken line) and lands on the point 28 of the stub flank surface 25a one lower. At this time, the overlap w between the male screw thread 13a and the female screw thread 17a becomes the maximum and is difficult to slip through, but the screw fitting is most stable.
[0022]
The stubbing flank surface 15a of the male screw thread 13a can be landed on the stubbing flank surface 25a of the female screw thread 17a in this way, as is apparent from the drawing, with a predetermined width like a square screw, trapezoidal screw or buttress screw. The thread crest surface 14a of the male thread 13a and the thread crest surface 22a of the female thread 17a are opposite to the thread taper angle α with respect to the plane D parallel to the tube axis C so that they do not compete during insertion. This is because the stub is inclined with a clearance angle β. Ideally, these thread crest surfaces 14a and 22a do not compete with each other even if parallel to the tube axis C, but there is a slight inclination when the tapered male thread portion 11a is inserted, and the threaded joint itself also has a false circle. Actually, the male and female screw threads 13a and 17a compete with each other. The larger the stub clearance angle β, the more secure it is to secure the screwing. However, if it is too large, the height h of the load flank surfaces 23a, 26a that bears the load when the joint is pulled becomes low, and the taper male thread portion 11a is tapered. Since there is a problem that the female screw portion 12a is easily removed, it is not appropriate to make it larger than necessary. As a result of the experiment, it is practically sufficient that the stub clearance angle β is at least 1 ° to 3 °. In addition, the code | symbol 16a in FIG. 1 shows a pipe, 18a shows a trough part, and 19a shows a pipe (or short pipe).
[0023]
FIG. 6 shows a state where the taper male screw portion 11a and the taper female screw portion 12a of the pipe joint 10a have been tightened, that is, a fitted state.
The feature of the taper screw shape in the case of the pipe joint 10a according to the present embodiment is that the height h of the load flank surfaces 23a and 26a is lower than that of the stubbing flank surfaces 15a and 25a. Since this may cause the taper male screw portion 11a to come off, the following two methods are employed to increase the resistance.
First, as shown in FIG. 6, the load flank surfaces 23 a and 26 a are inclined by an angle γ in a direction that is difficult to come out from the vertical surface Vs with respect to the tube axis C.
Second, as shown in FIG. 7, the entire surface of the screw thread top surfaces 14a and 22a of the male and female thread threads 13a and 17a is not set to the stubbing clearance angle β, but only the side close to the stubbing flank surfaces 15a and 25a is stubbed clearance. The angle β is set, and the side close to the remaining load flank surfaces 23a and 26a is parallel to the pipe axis C, and the thread height is gained only in the blackened portion of the thread top portion in FIG. 7, or one of the thread top surfaces 14a and 22a. Is the height of the load flank surfaces 23a and 26a by making the entire surface stubbing clearance angle β or partially the stubbing clearance angle β, the rest parallel to the tube axis C, and the other the thread crest surface parallel to the entire surface tube axis C. h1 is kept high.
Here, the phrase “parallel to the tube axis C” includes not only the case where the tube axis C and the top surface of the screw thread are exactly parallel, but also the case where the tube axis C is tilted to the extent that it does not interfere with the stubbing (insertion) (the same applies hereinafter).
[0024]
FIGS. 8 and 9 are integral type and coupling type pipe joints showing an embodiment of the present invention each having the thread shape of FIG.
[0025]
FIG. 10 shows male screw threads 13 and 13a and female screw threads in a taper male and female screw portions 11 and 12 each having a thread lead L and a double thread having a pitch p (L / 2). 17 and 17a have shown the state of the insertion position in which the corner parts 24 and 27 of each screw thread top face 14 and 22 correspond on a virtual taper T line. In the male screw thread 13a and the female screw thread 17a, those corresponding to the elements of the male screw thread 13 and the female screw thread 17 are described with a suffix a.
From this state, if the thread crest surface 14 of the male thread 13 of the taper male thread 11 passes through the thread crest 22 of the female thread 17 of the taper female thread 12, the corner 24 is parallel to the pipe axis C of the pipe joint 10. It falls along the surface D (indicated by a broken line), slightly displaces the lower female thread 17a, and lands on the point 28 of the stubbing flank surface 25 of the lower female thread 17 below. That is, the male screw thread 13a and the female screw thread 17a having a low height may be set low enough not to hinder the high male screw thread 13 from landing on the female screw thread 17 having a high height. In this way, if the stubbing flank surface 15 of the high male thread 13 overlaps the stubbing flank surface 25 of the high female thread 17, the overlap w of the male screw 13 and the female thread 17 at this time Is the maximum. This is twice that of the single thread, and landing stability is further improved.
[0026]
The reason why the stubbing flank surface 15 of the male screw thread 13 can be landed on the stubbing flank surface 25 of the female screw thread 17 is that, as is apparent from the figure, every other low screw thread is arranged. is there. In FIG. 10, reference numeral 16 denotes a pipe, reference numeral 18 denotes a trough, reference numeral 19 denotes a pipe, and reference numeral 26 denotes a load flank surface of the female thread 17.
[0027]
FIG. 11 and FIG. 12 are integral type and coupling type pipe joints showing an embodiment of the present invention each having the thread shape of FIG.
[0028]
FIG. 13 shows male thread 13, 13 a, female thread in a tapered male and female threaded portion 11, 12 consisting of a thread lead L and a double thread with a pitch p (L / 2), with the thread height varied every other thread. 17 and 17a are in a state in which the points of the respective thread crest surfaces 14 and 22 are in contact with the virtual taper T, and the corner portion 24 between the stubbing flank surface 15 and the thread crest surface 14 of the male thread 13 is a tapered female thread portion. 12 shows a state where the stubbing flank surface 25 and the thread top surface 22 of the twelve female screw threads 17 are in contact with the corner portion 27, that is, the insertion position. In the male screw thread 13a and the female screw thread 17a, those corresponding to the elements of the male screw thread 13 and the female screw thread 17 are described with a suffix a.
From this state, if the corner portion 24 of the male screw thread 13 of the tapered male screw portion 11 passes through the corner portion 27 of the female screw thread 17 of the taper female screw portion 12, the corner portion 24 is parallel to the surface D parallel to the tube axis C of the pipe joint 10. It falls along (shown by a broken line), slightly evacuates the lower female thread 17a, and lands on the point 28 of the stubbing flank surface 25 of the female thread 17 below. That is, the male screw thread 13a and the female screw thread 17a having a low height may be set low enough not to hinder the high male screw thread 13 from landing on the female screw thread 17 having a high height. In this way, if the stubbing flank surface 15 of the high male thread 13 overlaps the stubbing flank surface 25 of the high female thread 17, the overlap w of the male screw 13 and the female thread 17 at this time Is the maximum. This is twice that of the single thread, and landing stability is further improved.
[0029]
The reason why the stubbing flank surface 15 of the male thread 13 can land on the stubbing flank surface 25 of the female thread 17 is that, as is apparent from the figure, every other low thread is disposed. In addition, the thread top surface 14 of the male thread 13 having a predetermined width, such as a square screw or a trapezoidal thread, and the thread top surface 22 of the female thread 17 are parallel to the tube axis C so as not to compete at the time of insertion. This is because the stub clearance angle β is provided on the side opposite to the screw taper angle α with respect to the surface D and is inclined. Ideally, the thread crest surfaces 14 and 22 do not compete with each other even if they are parallel to the tube axis C (the supplementary line of the broken line in FIG. 13). The male and female screw threads 13 and 17 may compete with each other. The larger the stub clearance angle β, the better the screwing-in, but if it is too large, the height h of the load flank surfaces 23, 23a, which bears the load when the joint is pulled, is lowered, and the tapered male threaded portion 11 is separated from the tapered female threaded portion 12. Since there is a problem that it is easy to come off, it is not appropriate to make it larger than necessary. In particular, since the height of the screw threads 13 and 13a and the height of the female threads 17 and 17a itself is sacrificed, the height of the screw threads is sacrificed. Decide to secure the screw height. In FIG. 13, reference numeral 16 denotes a pipe, 18 denotes a trough, 19 denotes a pipe, and 26 denotes a load flank surface of the female thread 17.
[0030]
FIG. 14 and FIG. 15 are integral type and coupling type pipe joints showing an embodiment of the present invention each having the thread shape of FIG.
[0031]
As described above, the example of the double thread has been described in detail, but the tightening becomes faster as the number of threads increases. Therefore, the method of attaching the height of the thread is also mentioned for the three-thread screw and the four-thread screw. FIG. 16 (A) shows a case where three threads are arranged every two high threads, that is, every (number of threads-1) threads.
The male screw thread 13c is in a position where the landing can be seen through the female screw thread 17d in a state of passing through the female screw thread 17c. The overlapping of the stubbing flank surfaces can be widened and can stably land on the female thread 17d in a wide range within the screw lead L. However, if the state of fitting is imagined, it has the disadvantage that the fitting height becomes narrow as shown in the figure. In FIG. 16A, reference numeral 13d denotes a high male thread.
[0032]
In FIG. 16B, in order to eliminate this drawback, the height of the female thread threads 17g and 17h between the high female thread threads 17e and 17f is increased at the expense of the stubbing position and the landing width. is there. The male screw threads 13e and 13f can land on the female screw threads 17h and 17f, respectively. In FIG. 16B, reference numerals 13g and 13h also indicate male threads.
FIG. 17A shows a case where four threads are used and every other high thread is arranged. The stubability (workability from insertion to screwing) and the screw fitting state are the same as those of the double thread, and the screwing speed can be double that of the double thread. Male thread 13i, 13k can land on female thread 17k, 17n, respectively.
FIG. 17B shows a case where four threads are arranged every three high threads, that is, every (number of threads-1) threads. The male screw thread 13p is in a position where the landing can be seen through the female screw thread 17t while passing through the female screw thread 17p. As in FIG. 16A, the stubbing property is good, but the joint efficiency is sacrificed. If the relative positions of the male thread and female thread can be controlled in the threading process, the stubbing performance has a sufficient margin even in the case of FIGS. 16 (B) and 17 (A). ) And FIG. 17 (B) are suitable if the joint efficiency is also taken into account in FIG. 16 (B) and FIG.
[0033]
Even if the number of threads is increased in this way, in order to improve the threading of the male thread during stubbing, the idea of attaching a slope opposite to the thread taper to the thread top surface of the high thread is the same as in the case of two threads. It is the same.
It has already been described with reference to FIG. 22 (A) that even with the current API buttress joint, it is possible to tighten immediately after insertion if the insertion position is appropriately selected. The main point is that the taper is obtained from any position from the position shown in FIG. 22A to the point where the corner R of the stubbing flank 71 of the male thread 63 contacts the corner R of the stubbing flank 72 of the taper female thread 62. If the male screw portion 61 is dropped vertically, the male screw stubbing flank surface 71 can be placed on the female screw stubbing flank surface 72, so that the taper male screw portion 61 can be fitted into the taper female screw portion 62.
[0034]
The problem is how to make the positional relationship between the male screw and the female screw as shown in FIG.
In this embodiment, the outer surface of the pin and the coupling (or box) is marked at the time of threading so that the male screw row and the female screw row correspond to the center of the above-described range where the insertion is possible. At times, when the places with the marks were aligned, the pin and the box were always in a suitable position for screwing.
That is, the center mark on the virtual tapered surface T shown in FIG.
Considering the reference position of the thread cutting tool 29, as shown in FIGS. 3A and 3B, in the male threading path, (r, Zm) is passed, while in the female threading path, (r , Zf), the relationship between the male thread cutting tool 28 and the female thread cutting tool 29 at the start of threading and the pipes 16 and 19 is set, and the blade motion surfaces Fm and Ff at that time intersect with the pipes 16 and 19, respectively. Marks 31 and 21 are attached to the circumferential positions of the pipes 16 and 19. In this way, if the tapered male threaded portion 11 and the tapered female threaded portion 12 with the marks 31 and 21 are inserted with the positions of the marks 31 and 21 aligned in the circumferential direction, the positional relationship shown in FIG. The original male screw row and the female screw row that allow the stubbing flank surface 15 of the male screw thread 13 to overlap the stubbing flank surface 25 of the female screw screw 17 without competing with the screw thread top surfaces 14 and 22 of the female screw threads 13 and 17. Can be reproduced and smooth insertion of the tapered male screw portion 11 and subsequent screwing are possible. In FIG. 2, reference numerals 23 and 26 denote load flank surfaces, and reference numeral 30 denotes a tip of the tapered male screw portion 11.
[0035]
The present invention can be applied to the pipe joint shape shown in FIG. 18 in addition to the above embodiment. 18 (A) is a pipe joint 10b having only a fastening screw, FIG. 18 (B) is a pipe joint 10c having a metal seal portion at the tip of a screw fitting portion, and FIG. 18 (C) is (A) or This is a pipe joint 10d in which the uniform taper thread portion of (B) is divided into two stages. In FIG. 18, reference numerals 11b to 11d denote tapered male screw parts, and reference numerals 12b to 12d denote tapered female screw parts.
[0036]
【Example】
Subsequently, an example of the pipe joint according to the embodiment will be described with reference to FIG. FIG. 19 shows a 7-inch API buttress joint as an original form and improved stubbing performance based on the pipe joint according to the embodiment. FIG. 19A is a cross-sectional view showing the mating dimensions in the fitting state of the pipe joint.
The thread specifications differing from the API buttress joints are that the thread top surface of the male and female thread of each pin and box is inclined 3 ° to the opposite side of the thread row taper surfaces PT and BT with respect to the tube axis C, and the load flank surface is This is a point inclined with respect to a plane perpendicular to the tube axis C by 3 ° in the opposite direction to that of the API buttress joint.
[0037]
For the purpose of designating the relative positions of the pin, the male of the box, and the female screw thread during stubbing, as shown in FIG. 19C, the taper male screw portion has a radius r = 175.57 mm, and the tip 30 of the taper male screw portion. To Zm = 5.9 mm, the position of the male thread cutting tool 28 is set so that it coincides with the point P in the drawing (the intersection of the thread top surface of the male thread and the stubbing flank surface, that is, when there is no R machining). The mark 31 is marked at a circumferential position where the point P intersects the thread row taper surface (one-dot chain line PT) (see FIGS. 2 and 3). Similarly, as shown in FIG. 19B, in the taper female thread portion, the radius r = 175.57 mm, and the coordinate of Zf = 45.31 mm from the tip 20 of the taper female thread portion is point B in the figure (the thread top surface of the female thread). The position of the female thread cutting tool 29 is determined so as to coincide with the intersection of the stubbed flank surface, that is, when there is no R machining), and the point B is at a circumferential position where it intersects with the thread taper surface (two-dot chain line BT). Mark 21 (see FIGS. 2 and 3).
[0038]
In such a manner, threaded joint processing and marking were performed, and the taper male screw part was inserted into the taper female screw part in the vertical direction so that the positions of the marks 31 and 21 were aligned, and whether or not the screwing was possible from that state was tried. . As a result, it was confirmed that if the taper male screw portion is carefully inserted into the taper female screw portion so that the tube axis C does not tilt, it can be screwed in any position of 360 ° as well as the marking position.
In addition, although there was no problem in practical use, a phenomenon was observed in which only one place in the circumferential direction dropped after the insertion, and by one pitch. There, the relative positional relationship between the pin and the box is where the marks 31 and 21 are exactly 180 ° opposite. That is, it is guessed that the pin and the box were exactly in the position of FIG.
[0039]
20 (A is a female screw, B is a male screw) in the case of a double-threaded screw that applies the thread height design from a single-threaded screw without changing the above dimensions (FIG. 19 (A)). Shown in Also in this case, it was confirmed that it was possible to screw in as it was regardless of the 360 ° position as described above.
In order to eliminate the misalignment, the same work was performed by welding a 200 mm cylinder as a stubbing guide to the tip 20 of the taper female threaded portion. Continuous operation of stubbing and screwing without using nerves for centering. It was also confirmed that it was possible.
In the embodiment, the corner portion where the crest of the screw thread and the stubbing flank surface intersect can be rounded from the viewpoint of preventing seizure, for example.
[0040]
【The invention's effect】
In the pipe joint according to claim 1 and claim 2, the thread top surface of the male thread of the taper male thread part and the thread top surface of the female thread of the taper female thread part are defined as a square screw, a trapezoidal screw, or a buttress screw. It has a width, and both screw crest surfaces are inclined in the direction opposite to the thread row taper surface with respect to the plane parallel to the tube axis, so that the taper male thread portion is inserted and continued at any position of 360 °. Screwing continuous work is possible.
In the pipe joint according to claim 3 and claim 4, the thread top surface of the male thread of the taper male thread part and the thread top surface of the female thread of the taper female thread part are defined as a square screw, a trapezoidal screw, or a buttress screw. Since it has a width, a part of both screw thread top surfaces are inclined in the direction opposite to the thread row taper surface with respect to a surface parallel to the tube axis, and the remaining both screw thread top surfaces are parallel to the tube axis. The height of the load flank surface can be kept large, and the screw joint shape can be made difficult to come off.
[0042]
Claim 5 And claims 6 In the pipe joint described, when inserting the tapered male threaded portion into the tapered female threaded portion, a virtual tapered surface that contacts the top surface of the male thread of the tapered male threaded portion and a virtual tapered surface that contacts the top surface of the female thread of the tapered female threaded portion, If the taper male thread part is lowered in the vertical direction in the state in which the two threads match, the male thread thread top face does not compete with the female thread top face, and the male thread stubbing flank face becomes the female thread stubbing flank face. The taper male screw part and the taper female screw part are marked in the circumferential direction so that the positional relationship between the original male screw line and the female screw line that can overlap can be reproduced. The continuous operation of inserting the part and subsequent screwing becomes possible.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a state of an insertion position of a tapered threaded joint to which a pipe joint according to an embodiment of the present invention is applied.
FIG. 2 is a cross-sectional view illustrating a state of an appropriate insertion range of a taper screw joint to which the pipe joint is applied.
FIG. 3 is a perspective view for explaining a mark position during threading of the pipe joint.
FIG. 4 is a cross-sectional view illustrating the shape of an integral type taper threaded joint to which the pipe joint is applied.
FIG. 5 is a cross-sectional view illustrating the shape of a coupling type taper threaded joint to which the pipe joint is applied.
FIG. 6 is a cross-sectional view illustrating a fitting state of a taper threaded joint to which the pipe joint is applied.
FIG. 7 is a cross-sectional view illustrating a state of the insertion position of a taper screw joint to which the pipe joint is applied.
FIG. 8 is a cross-sectional view illustrating the shape of an integral type taper threaded joint to which the pipe joint is applied.
FIG. 9 is a cross-sectional view illustrating the shape of a coupling type taper screw joint to which the pipe joint is applied.
FIG. 10 is a cross-sectional view illustrating a state of an insertion position where the overlap of stubbing flank surfaces of a tapered threaded joint to which a pipe joint according to an embodiment of the present invention is applied is maximized.
FIG. 11 is a cross-sectional view illustrating the shape of an integral type taper threaded joint to which the pipe joint is applied.
FIG. 12 is a cross-sectional view illustrating the shape of a coupling type taper threaded joint to which the pipe joint is applied.
FIG. 13 is a cross-sectional view illustrating a state of an insertion position where the overlap of stubbing flank surfaces of a tapered threaded joint to which a pipe joint according to an embodiment of the present invention is applied is maximized.
FIG. 14 is a cross-sectional view illustrating the shape of an integral type taper threaded joint to which the pipe joint is applied.
FIG. 15 is a cross-sectional view illustrating the shape of a coupling type taper threaded joint to which the pipe joint is applied.
FIG. 16 is a cross-sectional view of a thread shape when the taper threaded joint has three threads.
FIG. 17 is a cross-sectional view of a screw shape when the taper threaded joint has four threads.
FIG. 18 is a cross-sectional view illustrating the shape of a tapered threaded joint to which the pipe joint is applied.
FIG. 19 is a detailed dimensional view of an embodiment of the pipe joint.
FIG. 20 is a detailed dimensional view of the same.
FIGS. 21A and 21B are a cross-sectional view and an enlarged view illustrating a state of screwing start of a pipe joint having a tapered tape thread for pipes according to a conventional example, respectively.
FIGS. 22A and 22B are a cross-sectional view and a detailed view of a screw shape, respectively, for explaining the start of screwing of an API buttress threaded joint.
[Explanation of symbols]
10: Pipe joint, 10a to 10d: Pipe joint, 11: Tapered male thread part, 11a to 11d: Tapered male thread part, 12: Tapered female thread part, 12a to 12d: Tapered female thread part, 13: Male thread, 13a: Male thread, 14: Thread top surface, 14a: Thread top surface, 15: Stubbing flank surface, 15a: Stubbing flank surface, 16: Pipe, 16a: Pipe, 17: Female thread, 17a: Female thread, 18: Valley, 18a : Tanibe, 19: pipe 19a: pipe 20: tip, 21: mark, 22: screw top surface, 22a: screw top surface, 23: road flank surface, 23a: road flank surface, 24: corner portion, 24a: corner portion, 25: stubbing flank surface, 25a: Stubbing flank surface, 26: Road flank surface, 26a: Road flank surface, 27: Corner part, 27a: Corner part, 28: Male thread cutting tool, 29: Female thread cutting tool, 30: Tip, 31: Mark

Claims

In a pipe joint for screwing a pin formed with a single male threaded taper male thread part on the outer peripheral surface of the pipe tip part and a box formed with a taper female screw part screwed onto the taper male screw part on the inner peripheral surface of the pipe tip part ,
The thread top surface of the male thread of the taper male thread part and the thread top surface of the female thread of the taper female thread part have a predetermined width such as a square screw, a trapezoidal screw, or a buttress screw, and the both thread top surfaces are A pipe joint characterized by being inclined in a direction opposite to the thread row taper surface with respect to a plane parallel to the pipe axis.

A pipe into which a pin having a single threaded taper male thread portion formed on the outer peripheral surface of the distal end portion of the tube and a coupling having a taper female thread portion threadably engaged with the taper male thread portion on the inner peripheral surface of both ends of the short tube In the joint,
The thread top surface of the male thread of the taper male thread part and the thread top surface of the female thread of the taper female thread part have a predetermined width such as a square screw, a trapezoidal screw, or a buttress screw, and the both thread top surfaces are A pipe joint characterized by being inclined in a direction opposite to the thread row taper surface with respect to a plane parallel to the pipe axis.

In a pipe joint for screwing a pin formed with a single male threaded taper male thread part on the outer peripheral surface of the pipe tip part and a box formed with a taper female screw part screwed onto the taper male screw part on the inner peripheral surface of the pipe tip part ,
The thread top surface of the male thread of the taper male thread part and the thread top surface of the female thread of the taper female thread part have a predetermined width such as a square screw, a trapezoidal screw, or a buttress screw, A pipe joint characterized in that the portion is inclined in a direction opposite to the thread row taper surface with respect to a plane parallel to the pipe axis, and the remaining screw thread crest faces are parallel to the pipe axis.

A pipe into which a pin having a single threaded taper male thread portion formed on the outer peripheral surface of the distal end portion of the tube and a coupling having a taper female thread portion threadably engaged with the taper male thread portion on the inner peripheral surface of both ends of the short tube In the joint,
The thread top surface of the male thread of the taper male thread part and the thread top surface of the female thread of the taper female thread part have a predetermined width such as a square screw, a trapezoidal screw, or a buttress screw, A pipe joint characterized in that the portion is inclined in a direction opposite to the thread row taper surface with respect to a plane parallel to the pipe axis, and the remaining screw thread crest faces are parallel to the pipe axis.

In a pipe joint for screwing a pin formed with a single male threaded taper male thread part on the outer peripheral surface of the pipe tip part and a box formed with a taper female screw part screwed onto the taper male screw part on the inner peripheral surface of the pipe tip part ,
When the taper male screw portion is inserted into the taper female screw portion, a virtual taper surface in contact with the screw top surface of the male screw thread of the taper male screw portion and a virtual taper surface in contact with the screw thread top surface of the female screw thread of the taper female screw portion coincide with each other. In this state, if the taper male thread portion is lowered in the vertical direction, the male thread top surface does not compete with the female thread top surface, and the male thread stubbing flank surface is the female thread stubbing flank. In order to reproduce the positional relationship between the original male screw row and the female screw row that can overlap the surface, the taper male screw portion and the taper female screw portion are marked to coincide with the circumferential direction at the time of threading. Pipe fittings.

A pipe into which a pin having a single threaded taper male thread portion formed on the outer peripheral surface of the distal end portion of the tube and a coupling having a taper female thread portion threadably engaged with the taper male thread portion on the inner peripheral surface of both ends of the short tube In the joint,
When the taper male screw portion is inserted into the taper female screw portion, a virtual taper surface in contact with the screw top surface of the male screw thread of the taper male screw portion and a virtual taper surface in contact with the screw thread top surface of the female screw thread of the taper female screw portion coincide with each other. In this state, if the taper male thread portion is lowered in the vertical direction, the male thread top surface does not compete with the female thread top surface, and the male thread stubbing flank surface is the female thread stubbing flank. In order to reproduce the positional relationship between the original male screw row and the female screw row that can overlap the surface, the taper male screw portion and the taper female screw portion are marked to coincide with the circumferential direction at the time of threading. Pipe fittings.