JP3945752B2

JP3945752B2 - guide bush

Info

Publication number: JP3945752B2
Application number: JP2002006458A
Authority: JP
Inventors: 重雄長谷川; 由洋野島
Original assignee: Citizen Holdings Co Ltd; Citizen Watch Co Ltd
Current assignee: Citizen Holdings Co Ltd; Citizen Watch Co Ltd
Priority date: 2002-01-15
Filing date: 2002-01-15
Publication date: 2007-07-18
Anticipated expiration: 2022-01-15
Also published as: CN1298467C; JP2003211303A; CN1496293A; WO2003059558A1

Description

【０００１】
【発明の属する技術分野】
本発明は、旋削加工中の棒材をその被加工部位近傍で支持するガイドブッシュに関する。さらに本発明は、そのようなガイドブッシュを備えた自動旋盤に関する。
【０００２】
【従来の技術】
ＮＣ旋盤等の、種々の自動旋削加工を実施できる工作機械（本明細書で自動旋盤と総称する）において、工具による加工作業位置の近傍で旋盤機台上に設置され、主軸に把持された棒状の被加工素材（以下、棒材と称する）を、その先端の加工部位の近傍で支持する補助支持装置としてのガイドブッシュを備えたものが知られている。ガイドブッシュは、径方向へ弾性変形可能な中空筒状の棒材支持部を有し、この棒材支持部に、旋削加工中の棒材をその加工部位に振れが生じないように支持して、製品を高精度に加工成形することを可能にする。従来、自動旋盤では、旋削加工中に高速回転する棒材に対して固定的に配置される固定型のガイドブッシュと、棒材と共に高速回転する回転型のガイドブッシュとが、適宜選択して使用されている。
【０００３】
また、従来の自動旋盤において、製品となる棒材先端の加工長さ部分を加工作業位置に供給するため、及び加工途上でそのような加工長さ部分の長手方向所望位置に工具刃先を配置するために、棒材を把持した主軸が軸線方向へ移動する構成を有したものは周知である。この自動旋盤では、ガイドブッシュは、固定型及び回転型のいずれの形式においても、棒材支持部に棒材を心出し支持（すなわち棒材軸線を回転軸線に合致させるように支持）した状態で、主軸の軸線方向移動により送り出される棒材を、軸線方向へ正確に案内しつつ支持できることが要求される。そこで従来、加工作業開始前にガイドブッシュに加工対象棒材（丸棒、角棒）を挿入し、棒材支持部を弾性変形させてその内径寸法を棒材外径寸法に合わせて微調整することにより、棒材の心出し支持と軸線方向案内支持との双方を達成できるようにしている。
【０００４】
この種のガイドブッシュにおいて、棒材支持部を外筒と内筒との二層構造にして、加工対象棒材の外径寸法の変更や、棒材支持部の内周面（すなわち棒材支持面）の損耗程度に応じて適宜、内筒を交換できるようにしたガイドブッシュが提案されている（特開２００１−１３８１０２号公報参照）。このガイドブッシュは、自動旋盤に搭載した状態で、必要に応じて内筒のみを交換することにより、多様な外径寸法を有する異種棒材（丸棒、角棒）を支持することができ、また棒材支持面の損耗に起因する加工精度の低下に迅速に対処することができる。さらに、内筒を自己潤滑性に優れた材料から作製すれば、内筒の棒材支持面と加工対象棒材の外周面との隙間を実質的に排除するとともに、棒材の軸線方向送り時に内筒との摩擦によって生じ得る棒材外周面の傷を可及的に削減して、高品質の製品を製造することが可能になる。
【０００５】
【発明が解決しようとする課題】
上記した二層構造の棒材支持部を有する従来のガイドブッシュでは、棒材支持部の内径寸法を加工対象棒材の外径寸法に合わせて微調整できるように、一般的なすり割り構造を外筒に形成する一方で、内筒にはそれ自体の径寸法を拡縮可能とする所望の弾性を付与していた。このような弾性を有する内筒は、特にその材料自体を比較的柔軟な物質で構成した場合に、棒材の軸線方向送り時に棒材との摩擦により棒材支持面に損耗を生じる危惧がある。特に、加工対象棒材として、所定径に引抜き加工された引抜き材をそのまま使用する場合には、引抜き材の外形寸法精度の低さや面粗さに起因して内筒の損耗が生じ易くなり、結果として内筒の交換頻度が増加することが懸念される。
【０００６】
本発明の目的は、自動旋盤に設置されるガイドブッシュにおいて、加工対象棒材の外径寸法の変更や棒材支持面の摩耗に迅速に対処できる複層構造の棒材支持部を有し、しかも棒材支持面の耐摩耗性を著しく向上させることができるガイドブッシュを提供することにある。
本発明のさらに他の目的は、そのようなガイドブッシュを備えた高性能の自動旋盤を提供することにある。
【０００７】
【課題を解決するための手段】
上記目的を達成するために、請求項１に記載の発明は、中空筒状の基部と、基部の軸線方向一端に隣接して設けられる中空筒状の棒材支持部とを具備するガイドブッシュにおいて、棒材支持部は、基部に一体的に連結される外筒部分と、外筒部分の内側に設置され、各々が硬質材料から形成されるとともに互いに協働して筒状の棒材支持面を形成する複数の内筒片部材と、複数の内筒片部材を、外筒部分の内側で棒材支持面を形成する位置に、外筒部分から独立して変位可能に、弾性的に保持する弾性部材とを具備すること、を特徴とするガイドブッシュを提供する。
【０００８】
請求項２に記載の発明は、請求項１に記載のガイドブッシュにおいて、弾性部材は、隣り合う内筒片部材の間に介在してそれら内筒片部材を相互に弾性的に連結する弾性連結要素を備えるガイドブッシュを提供する。
請求項３に記載の発明は、請求項２に記載のガイドブッシュにおいて、弾性連結要素が液状ガスケットから形成されるガイドブッシュを提供する。
【０００９】
請求項４に記載の発明は、請求項１〜３のいずれか１項に記載のガイドブッシュにおいて、弾性部材は、外筒部分と複数の内筒片部材の各々との間に介在してそれら内筒片部材を外側から弾性的に支持する弾性中間筒を備えるガイドブッシュを提供する。
請求項５に記載の発明は、請求項４に記載のガイドブッシュにおいて、弾性中間筒が、外筒部分と複数の内筒片部材との間で圧縮されて弾性変形可能な軟質材料から形成されるガイドブッシュを提供する。
【００１０】
請求項６に記載の発明は、請求項１〜５のいずれか１項に記載のガイドブッシュにおいて、弾性部材は、複数の内筒片部材に係合してそれら内筒片部材を内側から弾性的に支持する弾性支持要素を備えるガイドブッシュを提供する。
請求項７に記載の発明は、請求項６に記載のガイドブッシュにおいて、弾性支持要素が、複数の内筒片部材を径方向外方へ弾性的に付勢するばねから形成されるガイドブッシュを提供する。
【００１１】
請求項８に記載の発明は、請求項１〜７のいずれか１項に記載のガイドブッシュにおいて、複数の内筒片部材の各々は、少なくとも棒材支持面を形成する部分がセラミックスから作製されるガイドブッシュを提供する。
請求項９に記載の発明は、請求項１〜８のいずれか１項に記載のガイドブッシュにおいて、棒材支持部の外筒部分が径方向へ弾性変形でき、外筒部分の弾性変形に伴って、複数の内筒片部材が形成する棒材支持面の内径寸法が変化するガイドブッシュを提供する。
請求項１０に記載の発明は、請求項１〜９のいずれか１項に記載のガイドブッシュを、棒材の加工作業位置近傍に設置してなる自動旋盤を提供する。
【００１２】
【発明の実施の形態】
以下、添付図面を参照して、本発明の実施の形態を詳細に説明する。全図面に渡り、対応する構成要素には共通の参照符号を付す。
図面を参照すると、図１は、本発明の第１の実施形態によるガイドブッシュ１０を示す。ガイドブッシュ１０は、自動旋盤において、主軸に把持された棒材をその先端の被加工部位の近傍で支持する中空筒状の補助支持装置として、工具による加工作業位置の近傍で旋盤機台上に設置されるものであり、回転型ガイドブッシュ及び固定型ガイドブッシュのいずれにも適用できる。
【００１３】
ガイドブッシュ１０は、中空筒状の基部１２と、基部１２の軸線方向一端に隣接して設けられ、自動旋盤で加工される棒材を軸線方向送り可能に心出し支持する中空筒状の棒材支持部１４とを備える。基部１２は、棒材支持部１４から離れた軸線方向後端側に、自動旋盤の旋盤機台上で主軸から送出された棒材を導入する開口端面１２ａを有し、開口端面１２ａに隣接して、棒材を非接触に受容する円筒状の内周面１２ｂと、外周面の雄ねじ部１２ｃとが形成される。
【００１４】
棒材支持部１４は、基部１２に一体的に連結される径方向へ弾性変形可能な外筒部分１６と、外筒部分１６の内側に設置され、各々が硬質材料から形成されるとともに互いに協働して実質的筒状の棒材支持面１８を形成する複数の内筒片部材２０と、それら内筒片部材２０を、外筒部分１６の内側で棒材支持面１８を形成する位置に弾性的に保持する弾性部材２２とを備えて構成される。棒材支持部１４は、支持対象の棒材の中心軸線に合致する中心軸線１４ａを有して、棒材を心出し支持（すなわち棒材軸線を旋削中の回転軸線に合致させるように支持）する。
【００１５】
図１及び図２に示すように、外筒部分１６は、各々の基端２４ａで基部１２に一体的に連結される複数（図示実施形態では３個）の縦割片２４を有する。それら縦割片２４は、外筒部分１６の周方向へ等間隔に設けられる複数（図示実施形態では３個）のスリット２６を介して、互いに周方向へ隣接して配置される。それらスリット２６は、基部１２から離れた軸線方向前端側の外筒部分１６の開口端面１６ａから基部１２に至る範囲で、棒材支持部１４の中心軸線１４ａに平行に、かつ中心軸線１４ａに関して放射状に形成される。それにより各縦割片２４は、基端２４ａを支点として、外筒部分１６の径方向へ板ばね状に弾性変形できるようになっている。
【００１６】
外筒部分１６を構成する３個の縦割片２４は、弓形に湾曲する内面２４ｂをそれぞれに有し、それら内面２４ｂが互いに協働して、外筒部分１６の実質的円筒状の内周面を構成する。この内周面は、各縦割片２４が弾性変形していない状態で、棒材支持部１４の中心軸線１４ａに合致する中心軸線を規定する。また、各縦割片２４には、その自由端すなわち外筒部分１６の開口端面１６ａに隣接して、径方向外方へ膨出するフランジ部分２８が形成される。各縦割片２４のフランジ部分２８の外周面には、基端２４ａに向けてテーパ状に延びる圧力受け面２８ａが形成される。
【００１７】
さらに、外筒部分１６の各縦割片２４には、開口端面１６ａに沿って内面２４ｂから径方向内方へ突出する爪３０が形成される。それら爪３０は、開口端面１６ａに向かってテーパ状に延びる係止面３０ａをそれぞれに有し、互いに協働して実質的環状の係止構造を形成する。
【００１８】
図１及び図３に示すように、ガイドブッシュ１０では、外筒部分１６の３個の縦割片２４に対応して、３個の内筒片部材２０が棒材支持部１４に組み込まれている。各内筒片部材２０は、外筒部分１６の対応の縦割片２４の内面２４ｂに隙間を介して対向する円弧面状の外面２０ａと、外面２０ａの反対側の円弧面状の内面２０ｂと、それら外面２０ａと内面２０ｂとの間に延びる一対の側面２０ｃとを有する。３個の内筒片部材２０は、それぞれの内面２０ｂが共通の円筒面上に実質的に位置するとともに、それぞれの一側面２０ｃが互いに隙間を介して対向する相対配置で、円筒形状に組み合わされる。この状態で、それら内筒片部材２０の内面２０ｂが互いに協働して、棒材を軸線方向送り可能に心出し支持する実質的円筒状の棒材支持面１８（中心軸線１８ａを有する）を形成する。
【００１９】
各内筒片部材２０は、その軸線方向一端面２０ｄに隣接して、径方向外方へ突出するフランジ部分３２を有する。各内筒片部材２０のフランジ部分３２には、軸線方向一端面２０ｄに向けてテーパ状に延びる係合面３２ａが形成される。また、１つの内筒片部材２０のフランジ部分３２には、その径方向外端面に沿って軸線方向へ延びる溝３２ｂが刻設される。
【００２０】
各内筒片部材２０に好適に使用できる硬質材料としては、セラミックスを挙げることができる。この場合、少なくとも棒材支持面１８を形成する内面２０ｂを含む部分を、アルミナ（Ａｌ₂ Ｏ₃ ）、ジルコニア（ＺｒＯ₂ ）、窒化珪素（Ｓｉ₃ Ｎ₄ ）、炭化珪素（ＳｉＣ）等の、耐摩耗性に優れたエンジニアリングセラミックスから作製することができる。特に、棒材支持面１８に要求される耐摩耗性、表面平滑性に加えて、棒材の挿入、送出を繰り返すことによる内筒片部材２０の破損を可及的に防止する観点で、衝撃強度や靭性に優れたジルコニアセラミックスから作製することが有利である。このような構成によれば、特に各内筒片部材２０の耐久性を著しく向上させることができる。
【００２１】
弾性部材２２は、周方向へ隣り合う内筒片部材２０の対向する側面２０ｃの間に介在して、それら内筒片部材２０を相互に弾性的に連結する複数（図では３個）の弾性連結要素３４を備える。ガイドブッシュ１０においては、それら弾性連結要素３４の各々は、隣り合う内筒片部材２０の対向側面２０ｃ間の空所に実質的全体に渡って充填される液状ガスケットから形成される。液状ガスケットは、各種機械部品の接合面間の封止用シール剤として知られており、それ自体、硬化後に接合面に対して所要の接着性を発揮するとともに、硬化状態でも所望の弾性を維持できるものである。弾性連結要素３４に好適に使用できる液状ガスケットとしては、例えばスリーボンド社から入手可能な「＃１２１５液状ガスケット」が挙げられる。
【００２２】
弾性連結要素３４は、周方向へ隣り合う内筒片部材２０を相対変位可能に相互連結して、棒材支持部１４の外筒部分１６の内側で３個の内筒片部材２０が互いに離散することを防止するとともに、それら内筒片部材２０を、円筒状の棒材支持面１８を形成する位置に弾性的に保持する。また、弾性連結要素３４は、３個の内筒片部材２０の外面２０ａにそれぞれ径方向内方への押圧力が負荷されたときに、隣り合う内筒片部材２０の対向側面２０ｃ間でそれぞれ多様に弾性変形する。それに伴い、３個の内筒片部材２０は、対向側面２０ｃ同士が弾性連結要素３４を介して互いに押し付けられるまでの範囲で径方向内方へ変位し、結果として、それら内筒片部材２０の内面２０ｂが形成する棒材支持面１８の内径寸法が減少する。各内筒片部材２０の外面２０ａへの押圧力が解除されると、弾性連結要素３４の弾性復元力下で、各内筒片部材２０が初期位置に復帰して、棒材支持面１８の内径寸法が復元する。
【００２３】
液状ガスケットからなる弾性連結要素３４は、図示のように内筒片部材２０の対向側面２０ｃ間の空所を全体に渡って封止するように設置されることにより、例えば後述する自動旋盤での棒材旋削加工中に切粉が内筒片部材２０間の空所に侵入することを防止できる。しかし、弾性連結要素３４の配置はこれに限定されず、例えば内筒片部材２０間の空所内の所望部位に局所的に設置されることにより、両内筒片部材２０を相互連結する構成とすることもできる。また、液状ガスケットに限らず、例えばゴム板等の弾性体と接着剤との組み合わせによって、弾性連結要素３４を構成することもできる。
【００２４】
弾性部材２２はさらに、外筒部分１６と３個の内筒片部材２０の各々との間に介在して、それら内筒片部材２０を外側から弾性的に支持する弾性中間筒３６を備える。図１及び図４に示すように、弾性中間筒３６は、外筒部分１６の３個の縦割片２４の内面２４ｂに当接される実質的円筒状の外面３６ａと、外面３６ａの反対側で、３個の内筒片部材２０の外面２０ａに当接される円筒状の内面３６ｂとを有する円筒状部材である。弾性中間筒３６には、その外面３６ａに沿って軸線方向へ直線状に延びる複数（図示実施形態では３個）のスリット３８が、周方向等間隔配置で形成される。それらスリット３８は、弾性中間筒３６の軸線方向全長に渡って外面３６ａに開口するとともに、内面３６ｂから離れて（すなわち内面３６ｂに開口することなく）放射状に形成される。その結果、弾性中間筒３６には、３個の弧状壁部分４０と、それら弧状壁部分４０をそれぞれの内面に沿って周方向へ一体的に相互連結する３個の肉薄の連結部分４２とが形成される。なお、１つの弧状壁部分４０には、その外面に沿って軸線方向へ延びる溝４４が刻設される。
【００２５】
弾性中間筒３６は、その外面３６ａに径方向内方への押圧力が負荷されたときに、３個の連結部分４２に応力が集中して、それら連結部分４２がそれぞれ多様に弾性変形する。それに伴い、３個の弧状壁部分４０は、隣り合う弧状壁部分４０が互いに接触するまでの範囲で、径方向内方へ変位する。それにより、弾性中間筒３６の内面３６ｂは本来の円筒形状から歪みを生じ、結果として弾性中間筒３６の実質的内径寸法が減少する。弾性中間筒３６の外面３６ａへの押圧力が解除されると、各連結部分４２の弾性復元力下で、各弧状壁部分４０が初期位置に復帰して、弾性中間筒３６の内径寸法が復元する。
【００２６】
弾性中間筒３６は、外筒部分１６の各縦割片２４に負荷される径方向内方への押圧力を、各縦割片２４の径方向内側に位置する対応の内筒片部材２０に確実に伝達するように作用する。また弾性中間筒３６は、複数の内筒片部材２０を径方向外側から支持することにより、それら内筒片部材２０を、円筒状の棒材支持面１８を形成する位置に弾性的に保持する。さらに、弾性中間筒３６は、外筒部分１６の３個の縦割片２４と３個の内筒片部材２０との間で両者からの圧力を受けて、隣り合う弧状壁部分４０が互いに接触するまでの範囲で、各弧状壁部分４０自体が圧縮されて弾性変形し得る程度の柔軟性を有する。このような特性を発揮し得る弾性中間筒３６の好適な軟質材料としては、例えば軸受材料等で「ターカイトＢ」の商品名で知られているフッ素樹脂系エンジニアリングプラスチック等の樹脂材料を挙げることができる。
【００２７】
ガイドブッシュ１０は、上記した各種構成要素を別々に作製した後に、以下のようにして組み立てることにより製造される。基部１２と棒材支持部１４の外筒部分１６とを一体に有するブッシュ本体は、所望の金属材料から切削工程等を経て作製される。そこで、「ターカイトＢ」等の樹脂材料から射出成形工程等を経て一体成形した弾性中間筒３６を、その外面３６ａが外筒部分１６の各縦割片２４の内面２４ｂに密着するように、各縦割片２４及び弾性中間筒３６の少なくとも一方を弾性変形させながら、外筒部分１６の内側に嵌入する。このとき、外筒部分１６の各縦割片２４と弾性中間筒３６の各弧状壁部分４０とを互いに位置合せし、１つの縦割片２４の内面２４ｂに突設した回り止め４６（図１）を、弾性中間筒３６の溝４４に挿入する。その結果、弾性中間筒３６は、外筒部分１６に対する回転が阻止された状態で、外筒部分１６の内側の所定位置に、弾性中間筒３６及び外筒部分１６の少なくとも一方が生じる弾性復元力下で保持される。
【００２８】
他方、ジルコニアセラミックス等の硬質材料からそれぞれに成形した３個の内筒片部材２０を、前述したように弾性連結要素３４により円筒形状に接合して内筒構造を作製する。この内筒構造を、外筒部分１６に嵌入した弾性中間筒３６の内面３６ｂに各内筒片部材２０の外面２０ａが密着するように、外筒部分１６及び弾性中間筒３６と内筒構造（弾性連結要素３４）との少なくとも一方を弾性変形させながら、外筒部分１６及び弾性中間筒３６の内側に嵌入する。このとき、外筒部分１６の各縦割片２４及び弾性中間筒３６の各弧状壁部分４０と、内筒構造の各内筒片部材２０とを互いに位置合せし、１つの縦割片２４の内面２４ｂに突設した第２の回り止め４８（図１）を、１つの内筒片部材２０のフランジ部分３２に形成した溝３２ｂに挿入する。その結果、内筒構造は、外筒部分１６に対する全ての内筒片部材２０の回転が阻止された状態で、外筒部分１６及び弾性中間筒３６の内側の所定位置に、内筒構造及び外筒部分１６の少なくとも一方が生じる弾性復元力下で保持される。
【００２９】
このようにしてガイドブッシュ１０を適正に組み立てると、内筒構造の３個の内筒片部材２０は、それらが形成する棒材支持面１８の中心軸線１８ａが、棒材支持部１４の中心軸線１４ａに合致する状態に保持される。また、内筒構造の各内筒片部材２０に形成したフランジ部分３２の係合面３２ａは、外筒部分１６の各縦割片２４に形成した爪３０の係止面３０ａに密に当接され、各内筒片部材２０の軸線方向端面２０ｄが外筒部分１６の開口端面１６ａに隣接して略同一平面上に配置される。この状態で内筒構造は、外筒部分１６の内側の所定位置から、外筒部分１６の外方へ意図せず突き出ることが阻止される。また、弾性中間筒３６は、各内筒片部材２０のフランジ部分３２によって、外筒部分１６の開口端面１６ａから離れた位置に実質的に遮蔽して配置される。その結果、比較的柔軟な材料からなる弾性中間筒３６は、旋削工程中に飛散する切り粉から隔離されるので、その損傷が防止される。
【００３０】
なおガイドブッシュ１０では、外筒部分１６の各縦割片２４、内筒構造の各内筒片部材２０、及び弾性中間筒３６の各弧状壁部分４０は、周方向へ互いにずれて配置されてもよい。また、外筒部分１６、内筒構造及び弾性中間筒３６が所期の弾性変形を生じ得ることを前提条件として、外筒部分１６の縦割片２４、内筒構造の内筒片部材２０、及び弾性中間筒３６の弧状壁部分４０の個数が互いに異なっていてもよく、また３個以外の様々な個数とすることもできる。
【００３１】
上記構成を有するガイドブッシュ１０において、外筒部分１６の３個の縦割片２４に径方向内方への外力を加えると、各縦割片２４が弾性変形すると同時に、各縦割片２４の内面２４ｂに接触する弾性中間筒３６の外面３６ａに各縦割片２４から径方向内方への外力が負荷され、それにより前述したように、弾性中間筒３６が弾性変形してその実質的内径寸法が減少する。それに伴い、弾性中間筒３６の内面３６ｂに接触する３個の内筒片部材２０の外面２０ａに、弾性中間筒３６から径方向内方への外力が負荷され、その結果、前述したように、弾性連結要素３４の弾性変形下で、それら内筒片部材２０の内面２０ｂが形成する棒材支持面１８の内径寸法が減少する。このとき同時に、外筒部分１６の各縦割片２４に形成した爪３０の係止面３０ａから、各内筒片部材２０に形成したフランジ部分３２の係合面３２ａに直接に押圧力が負荷され、この押圧力によっても棒材支持面１８の内径寸法が減少する。
【００３２】
この状態から、外筒部分１６の各縦割片２４への径方向外力を弱めると、各縦割片２４が弾性復元し、それに伴い弾性中間筒３６及び弾性連結要素３４が弾性復元して、棒材支持面１８の内径寸法が増加（復元）する。なお、棒材支持面１８の内径寸法が減少及び増加する間、３個の内筒片部材２０は、棒材支持面１８の中心軸線１８ａを棒材支持部１４の中心軸線１４ａに合致させた状態を維持しつつ、径方向へ変位する。このようにガイドブッシュ１０では、棒材支持部１４に径方向内方へ負荷される外力すなわち押圧力を調節することによって、３個の内筒片部材２０によって形成される棒材支持面１８の内径寸法を調節することができる。
【００３３】
ガイドブッシュ１０においては、３個の内筒片部材２０によって形成される棒材支持面１８の内径寸法は、ガイドブッシュ１０が非作用状態にある間、支持（加工）対象棒材の外径寸法よりも大きくなるように設定される。そして、ガイドブッシュ１０が作用状態に置かれる実際の加工作業の開始前に、棒材支持部１４に対象棒材を挿入し、上記したように棒材支持面１８の内径寸法を棒材の外径寸法に合わせて微調整することにより、棒材支持面１８と棒材外周面との間にμｍオーダの所望の微細隙間を得る。ガイドブッシュ１０は、作用状態においてこのような微細隙間を確保することにより、棒材を軸線方向送り可能に心出し支持することができる。
【００３４】
ここで、支持（加工）対象棒材として、所定径に引抜き加工された外形寸法精度の低い引抜き材をそのまま使用する場合には、棒材の最小外径部分に対して上記した微細隙間が形成されるように、棒材支持面１８の内径寸法を微調整する。この作用状態で、ガイドブッシュ１０に支持した棒材を軸線方向へ送る間に、棒材の外径寸法の増加により棒材支持面１８と棒材外周面との摩擦が増大すると、外筒部分１６の各縦割片２４は径方向外方へ変位できない状態にあるので、弾性中間筒３６の各弧状壁部分４０が、外筒部分１６と内筒構造との間で圧力を受けて前述したように弾性変形する。その結果、内筒構造の弾性連結要素３４の弾性変形下で、各内筒片部材２０が径方向外方へ変位し、棒材支持面１８の内径寸法が棒材の外径寸法に合わせて受動的に拡大する。このようにしてガイドブッシュ１０は、引抜き材からなる棒材をも、軸線方向送り可能に心出し支持することができる。しかもこのとき、各内筒片部材２０が硬質材料から形成されるので、棒材支持面１８の耐摩耗性を著しく向上させて、棒材との摩擦に起因する各内筒片部材２０の損耗の進行を可及的に抑制することができる。
【００３５】
上記構成を有するガイドブッシュ１０では、前述した組立手順とは逆の手順で、内筒構造及び弾性中間筒３６を外筒部分１６から必要に応じて取り外すことができるので、支持対象棒材の外径寸法の変更に対応して棒材支持部１４の内径寸法を変更するときには、棒材支持面１８の内径寸法が異なる他の内筒構造に交換すればよい。したがって、ガイドブッシュ１０を搭載した自動旋盤で多様な外径寸法を有する異種棒材（丸棒、角棒）を加工する際には、それら異種棒材に対応した内径寸法をそれぞれに有する多種類の内筒構造を用意し、基部１２と外筒部分１６とからなるブッシュ本体を自動旋盤に搭載したままで内筒構造のみを適宜交換することにより、異種棒材の高精度加工を順次実施できる。また、長時間の加工作業により各内筒片部材２０の内面２０ｂが摩耗したときにも、ブッシュ本体は交換せずに、内筒構造のみを適宜交換すればよい。ここでガイドブッシュ１０によれば、棒材支持面１８の耐摩耗性の向上により、内筒片部材２０を含む内筒構造の交換頻度を削減することができる。
【００３６】
次に図５を参照して、上記構成を有するガイドブッシュ１０を組み込んで備えた自動旋盤５０の主要部分の構成を説明する。ガイドブッシュ１０は、スリーブ部材５２、軸受装置５４及びフランジ部材５６を介して、旋盤機台上に設定された工具５８による加工作業位置の近傍で、機台上のコラム６０に回転可能に設置される。
【００３７】
ガイドブッシュ１０は、スリーブ部材５２の前端（図で左端）領域に軸線方向へ摺動可能にかつ相対回転不能に収納される。スリーブ部材５２の内周面前端には、ガイドブッシュ１０の棒材支持部１４の外周面に設けた複数の圧力受け面２８ａに接触可能な圧力負荷面６２が形成される。スリーブ部材５２の後端（図で右端）領域には、ガイドブッシュ１０の基部１２に設けた雄ねじ部１２ｃ（図１）に螺合する雌ねじ部を有した調節ナット６４が、軸線方向へ固定して回転可能に収納される。それにより、調節ナット６４が回転すると、ガイドブッシュ１０がスリーブ部材５２内で軸線方向へ移動する。
【００３８】
スリーブ部材５２の外周面の後端領域には、キー６６を介して被動歯車６８が取付けられる。被動歯車６８は、図示しない動力伝達機構を介して図示しないガイドブッシュ駆動源に連結され、ガイドブッシュ駆動源により、コラム６０の後方に設置される主軸７０の回転速度と同一の回転速度で回転駆動される。その結果、被動歯車６８、調節ナット６４、スリーブ部材５２及びガイドブッシュ１０が、フランジ部材５６の内部で一体的に、主軸７０の回転速度と同一の回転速度で回転する。
【００３９】
フランジ部材５６は、例えばボルト７２によりコラム６０に固定される。このように、ガイドブッシュ１０、スリーブ部材５２、フランジ部材５６、調節ナット６４及び被動歯車６８は、予め組み立てた回転型ガイドブッシュ装置として、自動旋盤５０のコラム６０の所定位置に取付けることができる。なお、ガイドブッシュ１０を固定型ガイドブッシュ装置として使用する場合は、軸受装置５４、被動歯車６８、ガイドブッシュ駆動源等が省略される。
【００４０】
主軸７０は、旋削加工すべき棒材Ｗを把持して、図示しない主軸駆動源により回転駆動される。主軸７０は、コラム６０の後方で、ガイドブッシュ１０の回転軸線と主軸７０の回転軸線とが互いに一致するようにして、軸線方向移動可能に設置される。主軸７０の前端領域には、棒材Ｗを把持可能な開閉式のチャック７４が収容される。チャック７４は、先端にすり割り部を有したいわゆるコレットチャックであり、すり割り部に径方向内方への外力すなわち押圧力が加わることにより、先端の棒材把持孔７６が縮径してチャック７４が閉じ、棒材Ｗを強固に固定的に把持するようになっている。すり割り部への径方向外力が解除されると、すり割り部が復元して棒材把持孔７６が拡径し、チャック７４が開いて棒材Ｗを解放する。
【００４１】
主軸７０にはさらに、中空筒状の作動部材７８が軸線方向へ移動可能に収容される。作動部材７８は、その前端領域にチャック７４を収容し、図示しないチャック駆動源により軸線方向前方（図で左方）へ移動することによって、チャック７４のすり割り部に径方向内方への押圧力を負荷してチャック７４を閉じる。この状態から、作動部材７８を軸線方向後方（図で右方）へ移動すれば、チャック７４が開かれる。なお、主軸７０の構成は上記に限定されるものではない。例えばチャックの開閉作動機構として、チャック後端に連結した作動部材をチャックとともに軸線方向後方へ移動することにより、チャックのすり割り部に径方向内方への押圧力を加える構成を採用することもできる。
【００４２】
上記構成を有する自動旋盤５０において、棒材Ｗの加工作業を実施する際には、まず、ガイドブッシュ１０の外筒部分１６に、加工対象の棒材Ｗの外径寸法に対応する名目内径寸法を有した内筒構造と、適当な弾性中間筒３６とを選択して取付け、コラム６０に搭載されたスリーブ部材５２に装着する。次いで、外筒部分１６に径方向内方への外力を加えない状態で、主軸７０に把持した棒材Ｗを主軸７０の軸線方向移動により、ガイドブッシュ１０の後方から棒材支持部１６に挿入する。その状態から、調節ナット６４を回してガイドブッシュ１０を軸線方向後方へ移動し、外筒部分１６の圧力受け面２８ａをスリーブ部材５２の圧力負荷面６２に押付ける。それにより、外筒部分１６の３個の縦割片２４（図１）を弾性変形させるとともに、弾性中間筒３６及び弾性連結要素３４の弾性変形下で３個の内筒片部材２０を径方向内方へ変位させて、棒材支持面１８と棒材Ｗの外周面との間にμｍオーダの所望の微小隙間を形成する。このようにして、ガイドブッシュ１０の棒材支持面１８の内径寸法を調節した後、ガイドブッシュ１０により棒材Ｗの被加工部位近傍を心出し支持しつつ、例えば工具５８により旋削加工を実施する。
【００４３】
ところで、上記したガイドブッシュ１０においては、棒材を軸線方向へ送る間に棒材の外径寸法が局所的に増加したときに、弾性中間筒３６の各弧状壁部分４０が外筒部分１６と各内筒片部材２０との間で圧縮されて弾性変形することにより、複数の内筒片部材２０が径方向外方へ変位して、棒材支持面１８の内径寸法が棒材の外径寸法に合わせて受動的に拡大するようになっている。このような弾性中間筒３６の作用を利用すれば、前述した棒材支持面１８の内径寸法調節に際し、棒材支持面１８と棒材外周面との間にμｍオーダの微小隙間を敢えて形成せずとも、棒材支持面１８を棒材外周面に当接させておくだけで、棒材を軸線方向送り可能に心出し支持することができる。
【００４４】
このような観点では、ガイドブッシュの棒材支持面の内径寸法調節機構を省略することもできる。図６は、そのような簡略化した構成を有する本発明の第２の実施形態によるガイドブッシュ８０を示す。ガイドブッシュ８０は、棒材支持部の外筒部分の構成以外は、前述したガイドブッシュ１０と実質的同一の構成を有するので、対応する構成要素には共通の参照符号を付してその説明を省略する。
【００４５】
ガイドブッシュ８０の棒材支持部８２は、基部１２に一体的に連結される外筒部分８４と、外筒部分８４の内側に設置される複数（３個）の内筒片部材２０と、それら内筒片部材２０を、外筒部分８４の内側で棒材支持面１８を形成する位置に弾性的に保持する弾性部材２２とを備える。棒材支持部８２は、支持対象の棒材の中心軸線に合致する中心軸線８２ａを有して、棒材を心出し支持する。外筒部分８４は、前述したガイドブッシュ１０の外筒部分１６におけるスリット２６を省略した構成を有するものであり、棒材支持部８２の中心軸線８２ａに合致する中心軸線を規定する円筒状の内周面８４ａを備える（図７）。したがって外筒部分８４は、径方向へ実質的に弾性変形できず、その内周面８４ａの内径寸法を変更できない。
【００４６】
弾性部材２２を構成する弾性中間筒３６は、その外面３６ａ（図４）が外筒部分８４の内周面８４ａに当接されるとともに、その内面３６ｂ（図４）が３個の内筒片部材２０の外面２０ａに当接されて、外筒部分８４とそれら内筒片部材２０との間に配置され、その状態で各内筒片部材２０を外側から支持する。このような構成を有する棒材支持部８２は、３個の内筒片部材２０が形成する棒材支持面１８の内径寸法を積極的には調節できないものである。その一方で棒材支持部８２は、棒材支持面１８に径方向外方への外力が負荷されたときに、弾性中間筒３６の各弧状壁部分４０（図４）が外筒部分８４と各内筒片部材２０との間で圧縮されて弾性変形することにより、それら内筒片部材２０を径方向外方へ変位させて、棒材支持面１８の内径寸法を受動的に拡大させることができる。
【００４７】
したがって、上記構成を有するガイドブッシュ８０は、前述した自動旋盤５０に搭載したときに、棒材支持面１８の内径寸法に対応する外径寸法を有した棒材を、棒材支持面１８を棒材外周面に当接させた状態で、軸線方向送り可能に心出し支持できる。ここで、棒材として外形寸法精度の低い引抜き材をそのまま使用した場合にも、弾性中間筒３６の各弧状壁部分４０の弾性変形可能範囲内で、棒材支持面１８の内径寸法を受動的に拡大／縮小させて、棒材を軸線方向送り可能に心出し支持することができる。
【００４８】
前述したガイドブッシュ１０、８０では、棒材支持部１４、８２に設置される複数の内筒片部材２０が、弾性連結要素３４を介して互いに相対変位可能に連結される構成を有していた。しかし本発明に係るガイドブッシュは、複数の内筒片部材が互いに分離した状態で外筒部分の内側に配置されてなる棒材支持部を有することもできる。図８は、そのような構成を有する本発明の第３の実施形態によるガイドブッシュ９０を示す。ガイドブッシュ９０は、棒材支持部の内筒片部材及び弾性部材の構成以外は、前述したガイドブッシュ１０と実質的同一の構成を有するので、対応する構成要素には共通の参照符号を付してその説明を省略する。
【００４９】
ガイドブッシュ９０の棒材支持部９２は、基部１２に一体的に連結される径方向へ弾性変形可能な外筒部分１６と、外筒部分１６の内側に設置され、各々が硬質材料から形成されるとともに互いに協働して実質的筒状の棒材支持面９４を形成する複数（３個）の内筒片部材９６と、それら内筒片部材９６を、外筒部分１６の内側で棒材支持面９４を形成する位置に弾性的に保持する弾性部材９８とを備えて構成される。棒材支持部９２は、支持対象の棒材の中心軸線に合致する中心軸線９２ａを有して、棒材を心出し支持する。
【００５０】
図９に示すように、ガイドブッシュ９０の各内筒片部材９６は、外筒部分１６の対応の縦割片２４の内面２４ｂ（図２）に隙間を介して対向する円弧面状の外面９６ａと、外面９６ａの反対側の円弧面状の内面９６ｂと、それら外面９６ａと内面９６ｂとの間に延びる一対の側面９６ｃとを有する。３個の内筒片部材９６は、それぞれの内面９６ｂが共通の円筒面上に実質的に位置するとともに、それぞれの一側面９６ｃが互いに隙間を介して対向する相対配置で、外筒部分１６の内側に収容される。この状態で、それら内筒片部材９６の内面９６ｂが互いに協働して、棒材を軸線方向送り可能に心出し支持する実質的円筒状の棒材支持面９４（中心軸線９４ａを有する）を形成する。
【００５１】
各内筒片部材９６は、その軸線方向一端面９６ｄに隣接して、径方向外方へ突出するフランジ部分１００を有する。各内筒片部材９６のフランジ部分１００には、軸線方向一端面９６ｄに向けてテーパ状に延びる係合面１００ａが形成されるとともに、その径方向外端面に沿って軸線方向へ延びる溝１００ｂが刻設される。さらに各内筒片部材９６には、その内面９６ｂと軸線方向一端面９６ｄ及び軸線方向他端面９６ｅとの境界領域に、鋭角断面の縁溝１０２がそれぞれ形成される。
【００５２】
各内筒片部材９６に好適に使用できる硬質材料としては、エンジニアリングセラミックスを挙げることができる。この場合、少なくとも棒材支持面９４を形成する内面９６ｂを含む部分を、耐摩耗性、衝撃強度、表面平滑性に優れたジルコニアセラミックスから作製することが有利である。このような構成によれば、特に棒材支持面９４の耐久性を著しく向上させることができる。
【００５３】
弾性部材９８は、外筒部分１６と３個の内筒片部材９６の各々との間に介在して、それら内筒片部材９６を外側から弾性的に支持する弾性中間筒３６と、３個の内筒片部材９６に係合してそれら内筒片部材９６を内側から弾性的に支持する一対の弾性支持要素１０４とを備える。弾性中間筒３６は、その外面３６ａ（図４）で、外筒部分１６の３個の縦割片２４の内面２４ｂに当接されるとともに、その内面３６ｂ（図４）で、３個の内筒片部材９６の外面９６ａに当接される。弾性中間筒３６は、外筒部分１６の各縦割片２４に負荷される径方向内方への押圧力を、各縦割片２４の径方向内側に位置する対応の内筒片部材９６に確実に伝達するように作用する。また弾性中間筒３６は、複数の内筒片部材９６を径方向外側から支持することにより、それら内筒片部材９６を、円筒状の棒材支持面９４を形成する位置に弾性的に保持する。さらに、弾性中間筒３６は、外筒部分１６の３個の縦割片２４と３個の内筒片部材９６との間で両者からの圧力を受けて、隣り合う弧状壁部分４０（図４）が互いに接触するまでの範囲で、各弧状壁部分４０自体が圧縮されて弾性変形し得る程度の柔軟性を有する。
【００５４】
図１０に示すように、一対の弾性支持要素１０４の各々は、ばね線材をＣリング状に曲成してなる環状のばねから形成される。それら弾性支持要素１０４は、それぞれの全長を略３等分した長さ領域で、各内筒片部材９６の一対の縁溝１０２にそれぞれ受容されて、３個の内筒片部材９６を径方向外方へ弾性的に付勢する。それにより、それら弾性支持要素１０４が互いに協働して、３個の内筒片部材９６を、円筒状の棒材支持面９４を形成する位置に弾性的に保持する。各弾性支持要素１０４は、内筒片部材９６同士の機械的相互連結機能を有さないが、３個の内筒片部材９６の外面９６ａにそれぞれ径方向内方への押圧力が負荷されたときには、弾性支持要素１０４自体の径寸法を縮小するように弾性変形する。それに伴い、３個の内筒片部材９６は、対向側面９６ｃ同士が互いに接触するまでの範囲で径方向内方へ変位し、結果として、それら内筒片部材９６の内面９６ｂが形成する棒材支持面９４の内径寸法が減少する。各内筒片部材９６の外面９６ａへの押圧力が解除されると、両弾性支持要素１０４の弾性復元力下で、各内筒片部材９６が初期位置に復帰して、棒材支持面９４の内径寸法が復元する。
【００５５】
ガイドブッシュ９０は、上記した各種構成要素を別々に作製した後に、以下のようにして組み立てることにより製造される。まず、前述したガイドブッシュ１０の組立工程と同様に、基部１２と棒材支持部９２の外筒部分１６とを一体に有するブッシュ本体に、弾性中間筒３６を組み付ける。このとき、外筒部分１６の１つの縦割片２４に設置した回り止め４６を、弾性中間筒３６の溝４４（図４）に挿入ことにより、外筒部分１６に対する弾性中間筒３６の回転を阻止する。なお、図１１に示すように、外筒部分１６の全ての縦割片２４には、その内面２４ｂから突出する第２の回り止め４８が設置される。
【００５６】
他方、ジルコニアセラミックス等の硬質材料からそれぞれに成形した３個の内筒片部材９６に、一対の弾性支持要素１０４を前述したように組み付けて、実質的円筒形状の内筒構造を作製する。この内筒構造を、外筒部分１６に嵌入した弾性中間筒３６の内面３６ｂに各内筒片部材９６の外面９６ａが密着するように、外筒部分１６及び弾性中間筒３６と内筒構造（弾性支持要素１０４）との少なくとも一方を弾性変形させながら、外筒部分１６及び弾性中間筒３６の内側に嵌入する。このとき、各縦割片２４及び弾性中間筒３６の各弧状壁部分４０と、内筒構造の各内筒片部材９６とを互いに位置合せし、各縦割片２４の内面２４ｂに突設した第２の回り止め４８を、対応の内筒片部材９６のフランジ部分１００に形成した溝１００ｂに挿入する。その結果、内筒構造は、外筒部分１６に対する全ての内筒片部材９６の回転が阻止された状態で、外筒部分１６及び弾性中間筒３６の内側の所定位置に、外筒部分１６及び弾性中間筒３６と内筒構造（弾性支持要素１０４）との少なくとも一方が生じる弾性復元力下で保持される。なお、好ましくはこの状態で、各弾性支持要素１０４はそれ自体の弾性復元力により、３個の内筒片部材９６の縁溝１０２内に固定的に受容保持される。
【００５７】
このようにしてガイドブッシュ９０を適正に組み立てると、内筒構造の３個の内筒片部材９６は、それらが形成する棒材支持面９４の中心軸線９４ａが、棒材支持部９２の中心軸線９２ａに合致する状態に保持される。また、内筒構造の各内筒片部材９６に形成したフランジ部分１００の係合面１００ａは、外筒部分１６の各縦割片２４に形成した爪３０の係止面３０ａ（図１１）に密に当接され、各内筒片部材９６の軸線方向端面９６ｄが外筒部分１６の開口端面１６ａ（図１１）に隣接して略同一平面上に配置される。この状態で内筒構造は、外筒部分１６の内側の所定位置から、外筒部分１６の外方へ意図せず突き出ることが阻止される。また、弾性中間筒３６は、各内筒片部材９６のフランジ部分１００によって、外筒部分１６の開口端面１６ａから離れた位置に実質的に遮蔽して配置される。その結果、比較的柔軟な材料からなる弾性中間筒３６は、旋削工程中に飛散する切り粉から隔離されるので、その損傷が防止される。
【００５８】
なおガイドブッシュ９０では、外筒部分１６の各縦割片２４、内筒構造の各内筒片部材９６、及び弾性中間筒３６の各弧状壁部分４０は、周方向へ互いにずれて配置されてもよい。また、外筒部分１６、内筒構造及び弾性中間筒３６が所期の弾性変形を生じ得ることを前提条件として、外筒部分１６の縦割片２４、内筒構造の内筒片部材９６、及び弾性中間筒３６の弧状壁部分４０の個数が互いに異なっていてもよく、また３個以外の様々な個数とすることもできる。
【００５９】
上記構成を有するガイドブッシュ９０は、前述したガイドブッシュ１０と同様に作用する。すなわち、外筒部分１６の３個の縦割片２４に径方向内方への外力を加えると、各縦割片２４が弾性変形すると同時に、各縦割片２４の内面２４ｂに接触する弾性中間筒３６の外面３６ａに各縦割片２４から径方向内方への外力が負荷され、それにより前述したように、弾性中間筒３６が弾性変形してその実質的内径寸法が減少する。それに伴い、弾性中間筒３６の内面３６ｂに接触する３個の内筒片部材９６の外面９６ａに、弾性中間筒３６から径方向内方への外力が負荷され、その結果、前述したように、一対の弾性支持要素１０４の弾性変形下で、それら内筒片部材９６の内面９６ｂが形成する棒材支持面９４の内径寸法が減少する。
【００６０】
この状態から、外筒部分１６の各縦割片２４への径方向外力を弱めると、各縦割片２４が弾性復元し、それに伴い弾性中間筒３６及び両弾性支持要素１０４が弾性復元して、棒材支持面９４の内径寸法が増加（復元）する。なお、棒材支持面９４の内径寸法が減少及び増加する間、３個の内筒片部材９６は、棒材支持面９４の中心軸線９４ａを棒材支持部９２の中心軸線９２ａに合致させた状態を維持しつつ、径方向へ変位する。このようにガイドブッシュ９０では、棒材支持部９２に径方向内方へ負荷される外力すなわち押圧力を調節することによって、３個の内筒片部材９６によって形成される棒材支持面９４の内径寸法を調節することができる。
【００６１】
ガイドブッシュ９０においては、３個の内筒片部材９６によって形成される棒材支持面９４の内径寸法は、ガイドブッシュ９０が非作用状態にある間、支持（加工）対象棒材の外径寸法よりも大きくなるように設定される。そして、ガイドブッシュ９０が作用状態に置かれる実際の加工作業の開始前に、棒材支持部９２に対象棒材を挿入し、上記したように棒材支持面９４の内径寸法を棒材の外径寸法に合わせて微調整することにより、棒材支持面９４と棒材外周面との間にμｍオーダの所望の微細隙間を得る。ガイドブッシュ９０は、作用状態においてこのような微細隙間を確保することにより、棒材を軸線方向送り可能に心出し支持することができる。
【００６２】
ここで、支持（加工）対象棒材として、所定径に引抜き加工された外形寸法精度の低い引抜き材をそのまま使用する場合には、棒材の最小外径部分に対して上記した微細隙間が形成されるように、棒材支持面９４の内径寸法を微調整する。この作用状態で、ガイドブッシュ９０に支持した棒材を軸線方向へ送る間に、棒材の外径寸法の増加により棒材支持面９４と棒材外周面との摩擦が増大すると、外筒部分１６の各縦割片２４は径方向外方へ変位できない状態にあるので、弾性中間筒３６の各弧状壁部分４０が、外筒部分１６と内筒構造との間で圧力を受けて前述したように弾性変形する。その結果、各内筒片部材９６が径方向外方へ変位し、棒材支持面９４の内径寸法が棒材の外径寸法に合わせて受動的に拡大する。このようにしてガイドブッシュ９０は、引抜き材からなる棒材をも、軸線方向送り可能に心出し支持することができる。しかもこのとき、各内筒片部材９６が硬質材料から形成されるので、棒材支持面９４の耐摩耗性を著しく向上させて、棒材との摩擦に起因する各内筒片部材９６の損耗の進行を可及的に抑制することができる。
【００６３】
なお、上記ガイドブッシュ９０に組み込んだ弾性支持要素１０４は、弾性連結要素３４を有する前述したガイドブッシュ１０に組み込むこともできる。このような構成によれば、ガイドブッシュ１０における弾性部材２２の弾性作用を強化できるので、内筒片部材２０の径方向変位動作の応答性を向上させて、棒材支持部１４による一層高精度の心出し支持特性を獲得できる。また、液状ガスケットからなる弾性連結要素３４を用いて複数の内筒片部材２０を円筒状に組み合わせる際に、各内筒片部材２０の位置精度が多少低く組み合わされていても、弾性支持要素１０４の支持作用によって、結果的に各内筒片部材２０の位置精度を獲得することができる。それにより、ガイドブッシュ１０の製造工程が簡略化され、内筒片部材２０を交換する際にもその作業コストが削減される。
【００６４】
【発明の効果】
以上の説明から明らかなように、本発明によれば、自動旋盤に設置されるガイドブッシュにおいて、複層構造の棒材支持部を備えたことにより加工対象棒材の外径寸法の変更や棒材支持面の摩耗に迅速に対処できるだけでなく、棒材支持面の耐摩耗性を著しく向上させることができる。したがって本発明によれば、ガイドブッシュの特に棒材支持面の損耗が、自動旋盤における製品の加工精度及び製造コストに及ぼす影響を可及的に低減でき、引抜き材からなる棒材を用いる場合にも高品質の製品を製造することが可能になる。
【図面の簡単な説明】
【図１】本発明の第１実施形態によるガイドブッシュの、（ａ）線Ｉ−Ｉに沿った断面図、及び（ｂ）軸線方向端面図である。
【図２】図１のガイドブッシュにおける基部及び外筒部分の、（ａ）線II−IIに沿った断面図、及び（ｂ）軸線方向端面図である。
【図３】図１のガイドブッシュにおける内筒構造の、（ａ）線III−IIIに沿った断面図、及び（ｂ）軸線方向端面図である。
【図４】図１のガイドブッシュにおける弾性中間筒の、（ａ）線IV−IVに沿った断面図、及び（ｂ）軸線方向端面図である。
【図５】図１のガイドブッシュを搭載した自動旋盤の主要部を示す断面図である。
【図６】本発明の第２実施形態によるガイドブッシュの、（ａ）線VI−VIに沿った断面図、及び（ｂ）軸線方向端面図である。
【図７】図６のガイドブッシュにおける基部及び外筒部分の、（ａ）線VII−VIIに沿った断面図、及び（ｂ）軸線方向端面図である。
【図８】本発明の第３実施形態によるガイドブッシュの、（ａ）線VIII−VIIIに沿った断面図、及び（ｂ）軸線方向端面図である。
【図９】図８のガイドブッシュにおける複数の内筒片部材の、（ａ）線IX−IXに沿った断面図、及び（ｂ）軸線方向端面図である。
【図１０】図８のガイドブッシュにおける弾性支持要素の正面図である。
【図１１】図８のガイドブッシュにおける基部及び外筒部分の、（ａ）線XI−XIに沿った断面図、及び（ｂ）線Ｂ−Ｂに沿った断面図である。
【符号の説明】
１０、８０、９０…ガイドブッシュ
１２…基部
１４、８２、９２…棒材支持部
１６、８４…外筒部分
１８、９４…棒材支持面
２０、９６…内筒片部材
２２、９８…弾性部材
２４…縦割片
３０…爪
３４…弾性連結要素
３６…弾性中間筒
５０…自動旋盤
７０…主軸
１０４…弾性支持要素[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a guide bush for supporting a bar during turning in the vicinity of a portion to be processed. Furthermore, the present invention relates to an automatic lathe provided with such a guide bush.
[0002]
[Prior art]
In a machine tool (generally referred to as an automatic lathe in this specification) such as an NC lathe that can perform various automatic turning operations, a rod-like shape that is installed on a lathe machine stand in the vicinity of a machining work position by a tool and gripped by a spindle A material having a guide bush as an auxiliary support device for supporting a workpiece material (hereinafter referred to as a bar) in the vicinity of the processing portion at the tip thereof is known. The guide bush has a hollow cylindrical bar support part that can be elastically deformed in the radial direction. The bar support part supports the bar being turned so that there is no wobbling in the processed part. The product can be processed and molded with high accuracy. Conventional automatic lathes use a fixed guide bush that is fixedly mounted on a bar that rotates at high speed during turning and a rotary guide bush that rotates at a high speed together with the bar. Has been.
[0003]
Further, in a conventional automatic lathe, a tool cutting edge is arranged at a desired position in the longitudinal direction of such a processing length portion in order to supply the processing length portion of the tip of a bar material to be a product to a processing work position. For this reason, it is well known that the main shaft holding the bar moves in the axial direction. In this automatic lathe, the guide bush is in a state in which the bar is centered and supported (that is, supported so that the bar axis is aligned with the rotation axis) in the bar support part in both the fixed type and the rotary type. It is required that the bar fed by the movement of the main shaft in the axial direction can be supported while being accurately guided in the axial direction. Therefore, conventionally, before starting the machining operation, the bar to be machined (round bar, square bar) is inserted into the guide bush, the bar support part is elastically deformed, and the inner diameter is finely adjusted to match the bar outer diameter. This makes it possible to achieve both the centering support and the axial guide support of the bar.
[0004]
In this type of guide bush, the bar support part has a two-layer structure of an outer cylinder and an inner cylinder, and the outer diameter of the bar to be processed is changed, or the inner peripheral surface of the bar support part (ie, the bar support) A guide bush has been proposed in which the inner cylinder can be appropriately replaced according to the degree of wear of the surface (see Japanese Patent Laid-Open No. 2001-138102). This guide bush can support dissimilar bar materials (round bar, square bar) with various outer diameters by replacing only the inner cylinder as necessary while mounted on an automatic lathe. Further, it is possible to quickly cope with a decrease in processing accuracy due to wear of the bar support surface. Furthermore, if the inner cylinder is made of a material having excellent self-lubricating properties, the gap between the bar support surface of the inner cylinder and the outer peripheral surface of the bar to be processed is substantially eliminated, and at the time of axial feeding of the bar High-quality products can be manufactured by reducing as much as possible scratches on the outer peripheral surface of the bar material that may be caused by friction with the inner cylinder.
[0005]
[Problems to be solved by the invention]
In the conventional guide bush having the above-mentioned two-layered bar support part, a general slot structure is used so that the inner diameter dimension of the bar support part can be finely adjusted according to the outer diameter dimension of the bar to be processed. While the outer cylinder is formed, the inner cylinder is provided with a desired elasticity that allows the diameter of the inner cylinder to be enlarged or reduced. The inner cylinder having such elasticity may cause wear on the bar support surface due to friction with the bar when the bar is fed in the axial direction, particularly when the material itself is made of a relatively soft material. . In particular, when using a drawn material that has been drawn to a predetermined diameter as a processing target bar, the inner cylinder is likely to be worn due to the low external dimensional accuracy and surface roughness of the drawn material, As a result, there is a concern that the replacement frequency of the inner cylinder will increase.
[0006]
The object of the present invention is a guide bush installed in an automatic lathe, having a multi-layered bar support that can quickly cope with changes in the outer diameter of the bar to be processed and wear of the bar support surface, Moreover, it is an object of the present invention to provide a guide bush that can remarkably improve the wear resistance of the bar support surface.
Still another object of the present invention is to provide a high-performance automatic lathe equipped with such a guide bush.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a guide bush comprising a hollow cylindrical base portion and a hollow cylindrical rod support portion provided adjacent to one axial end of the base portion. The bar support part is installed on the inner side of the outer cylinder part integrally connected to the base part, and is formed of a hard material and cooperates with each other to form a cylindrical bar support surface. A plurality of inner cylinder piece members and a plurality of inner cylinder piece members at a position where a bar support surface is formed inside the outer cylinder portion. Can be displaced independently from the outer cylinder part, A guide bush characterized by comprising an elastic member that is elastically held.
[0008]
According to a second aspect of the present invention, in the guide bush according to the first aspect, the elastic member is interposed between adjacent inner cylindrical piece members and elastically connects the inner cylindrical piece members to each other. A guide bush comprising the element is provided.
The invention according to claim 3 provides the guide bush according to claim 2, wherein the elastic connecting element is formed of a liquid gasket.
[0009]
The invention according to claim 4 is the guide bush according to any one of claims 1 to 3, wherein the elastic member is interposed between the outer cylinder portion and each of the plurality of inner cylinder piece members. Provided is a guide bush including an elastic intermediate cylinder that elastically supports an inner cylinder piece member from the outside.
According to a fifth aspect of the present invention, in the guide bush according to the fourth aspect, the elastic intermediate cylinder is formed of a soft material that is elastically deformable by being compressed between the outer cylinder portion and the plurality of inner cylinder piece members. Provide a guide bush.
[0010]
According to a sixth aspect of the present invention, in the guide bush according to any one of the first to fifth aspects, the elastic member engages with the plurality of inner cylindrical piece members and elastically causes the inner cylindrical piece members to be elastic from the inside. A guide bushing is provided with a resiliently supporting elastic support element.
The invention according to claim 7 is the guide bush according to claim 6, wherein the elastic support element is formed of a spring that elastically biases the plurality of inner cylindrical piece members radially outward. provide.
[0011]
The invention according to an eighth aspect is the guide bush according to any one of the first to seventh aspects, wherein each of the plurality of inner cylindrical piece members is made of ceramics at least at a portion forming the bar support surface. Provide a guide bush.
According to a ninth aspect of the present invention, in the guide bush according to any one of the first to eighth aspects, the outer cylindrical portion of the bar support portion can be elastically deformed in the radial direction, and the elastic deformation of the outer cylindrical portion is accompanied. Thus, a guide bush is provided in which the inner diameter dimension of the bar support surface formed by the plurality of inner cylinder piece members is changed.
A tenth aspect of the present invention provides an automatic lathe in which the guide bush according to any one of the first to ninth aspects is installed in the vicinity of a machining work position of a bar.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Corresponding components are denoted by common reference symbols throughout the drawings.
Referring to the drawings, FIG. 1 shows a guide bush 10 according to a first embodiment of the present invention. In an automatic lathe, the guide bush 10 serves as a hollow cylindrical auxiliary support device that supports a bar gripped by a spindle in the vicinity of a processed part at the tip thereof, and is placed on a lathe table near a machining work position by a tool. It is installed, and can be applied to both a rotating guide bush and a fixed guide bush.
[0013]
The guide bush 10 is provided with a hollow cylindrical base 12 and a hollow cylindrical bar provided adjacent to one end of the base 12 in the axial direction so as to center and support a bar processed by an automatic lathe so as to be axially fed. And a support unit 14. The base 12 has an open end surface 12a for introducing a bar fed from the main shaft on the lathe machine base of the automatic lathe on the rear end side in the axial direction away from the bar support 14 and is adjacent to the open end surface 12a. Thus, a cylindrical inner peripheral surface 12b that receives the bar material in a non-contact manner and an external threaded portion 12c on the outer peripheral surface are formed.
[0014]
The bar material support part 14 is installed inside the outer cylinder part 16 and the outer cylinder part 16 which is elastically deformable in the radial direction and is integrally connected to the base part 12 and is formed of a hard material and cooperates with each other. A plurality of inner cylinder piece members 20 that work to form a substantially cylindrical bar support surface 18, and these inner cylinder piece members 20 are positioned at positions where the bar support surface 18 is formed inside the outer cylinder portion 16. And an elastic member 22 that is elastically held. The bar support part 14 has a center axis 14a that matches the center axis of the bar to be supported, and supports the bar in a centered manner (that is, supports the bar axis so as to match the axis of rotation during turning). To do.
[0015]
As shown in FIGS. 1 and 2, the outer cylinder portion 16 has a plurality (three in the illustrated embodiment) of vertically split pieces 24 that are integrally connected to the base 12 at each base end 24 a. These vertically divided pieces 24 are arranged adjacent to each other in the circumferential direction via a plurality of (three in the illustrated embodiment) slits 26 provided at equal intervals in the circumferential direction of the outer cylinder portion 16. The slits 26 are in a range from the opening end surface 16a of the outer cylindrical portion 16 on the axial front end side away from the base portion 12 to the base portion 12, and are parallel to the central axis line 14a of the bar support 14 and radial with respect to the central axis line 14a. Formed. Accordingly, each of the vertically divided pieces 24 can be elastically deformed in a leaf spring shape in the radial direction of the outer cylinder portion 16 with the base end 24a as a fulcrum.
[0016]
The three vertically divided pieces 24 constituting the outer cylinder portion 16 each have an inner surface 24b curved in an arcuate shape, and the inner surface 24b cooperates with each other to form a substantially cylindrical inner periphery of the outer cylinder portion 16. Configure the surface. The inner peripheral surface defines a central axis line that matches the central axis line 14a of the bar support portion 14 in a state where each of the vertically divided pieces 24 is not elastically deformed. Further, each vertical split piece 24 is formed with a flange portion 28 that bulges outward in the radial direction, adjacent to the free end thereof, that is, the open end surface 16a of the outer cylinder portion 16. A pressure receiving surface 28a extending in a tapered shape toward the base end 24a is formed on the outer peripheral surface of the flange portion 28 of each vertical split piece 24.
[0017]
Further, each vertical split piece 24 of the outer cylinder portion 16 is formed with a claw 30 protruding radially inward from the inner surface 24b along the opening end surface 16a. Each of the claws 30 has a locking surface 30a extending in a tapered shape toward the opening end surface 16a, and cooperates with each other to form a substantially annular locking structure.
[0018]
As shown in FIGS. 1 and 3, in the guide bush 10, three inner cylinder piece members 20 are incorporated in the bar support portion 14 in correspondence with the three vertically divided pieces 24 of the outer cylinder portion 16. Yes. Each inner cylinder piece member 20 has an arcuate outer surface 20a facing the inner surface 24b of the corresponding vertical split piece 24 of the outer cylinder portion 16 via a gap, and an arcuate inner surface 20b opposite to the outer surface 20a. And a pair of side surfaces 20c extending between the outer surface 20a and the inner surface 20b. The three inner cylinder piece members 20 are combined in a cylindrical shape with their inner surfaces 20b substantially located on a common cylindrical surface and their one side surfaces 20c facing each other with a gap therebetween. . In this state, the inner surface 20b of the inner cylindrical piece member 20 cooperates with each other to form a substantially cylindrical bar support surface 18 (having a central axis 18a) for centering and supporting the bar so that it can be axially fed. Form.
[0019]
Each inner cylinder piece member 20 has a flange portion 32 that protrudes radially outward, adjacent to one axial end surface 20d thereof. The flange portion 32 of each inner cylinder piece member 20 is formed with an engagement surface 32a extending in a tapered shape toward the one axial end surface 20d. Further, a groove 32b extending in the axial direction along the radially outer end surface is formed in the flange portion 32 of one inner cylinder piece member 20.
[0020]
Examples of the hard material that can be suitably used for each inner cylinder piece member 20 include ceramics. In this case, at least a portion including the inner surface 20b that forms the bar support surface 18 is made of alumina (Al ₂ O _Three ), Zirconia (ZrO ₂ ), Silicon nitride (Si _Three N _Four ), Silicon carbide (SiC), and other engineering ceramics having excellent wear resistance. In particular, in addition to the wear resistance and surface smoothness required for the bar support surface 18, the impact is prevented in order to prevent damage to the inner cylinder piece member 20 due to repeated insertion and feeding of the bar as much as possible. It is advantageous to produce from zirconia ceramics excellent in strength and toughness. According to such a configuration, the durability of each inner cylinder piece member 20 can be remarkably improved.
[0021]
The elastic member 22 is interposed between the opposing side surfaces 20c of the inner cylinder piece members 20 adjacent to each other in the circumferential direction, and a plurality of (three in the figure) elasticity that elastically connect the inner cylinder piece members 20 to each other. A connecting element 34 is provided. In the guide bush 10, each of the elastic coupling elements 34 is formed of a liquid gasket that is filled substantially entirely in the space between the opposing side surfaces 20 c of the adjacent inner cylinder piece members 20. Liquid gaskets are known as sealing agents for sealing between the joint surfaces of various machine parts. They themselves exhibit the required adhesion to the joint surfaces after curing and maintain the desired elasticity even in the cured state. It can be done. Examples of the liquid gasket that can be suitably used for the elastic connecting element 34 include “# 1215 liquid gasket” available from ThreeBond.
[0022]
The elastic connecting element 34 interconnects the inner cylinder piece members 20 adjacent to each other in the circumferential direction so as to be relatively displaceable, and the three inner cylinder piece members 20 are separated from each other inside the outer cylinder portion 16 of the bar support portion 14. And the inner cylindrical piece member 20 is elastically held at a position where the cylindrical bar support surface 18 is formed. In addition, the elastic connecting element 34 is provided between the opposing side surfaces 20c of the adjacent inner cylinder piece members 20 when the radially inner inward pressing force is applied to the outer surfaces 20a of the three inner cylinder piece members 20, respectively. Various elastic deformations. Accordingly, the three inner cylindrical piece members 20 are displaced inward in the radial direction until the opposing side surfaces 20c are pressed against each other via the elastic connecting element 34. As a result, the inner cylindrical piece members 20 The inner diameter dimension of the bar support surface 18 formed by the inner surface 20b is reduced. When the pressing force to the outer surface 20a of each inner cylinder piece member 20 is released, each inner cylinder piece member 20 returns to the initial position under the elastic restoring force of the elastic connecting element 34, and the rod support surface 18 The inner diameter is restored.
[0023]
The elastic connecting element 34 made of a liquid gasket is installed so as to seal the space between the opposing side surfaces 20c of the inner cylinder piece member 20 as shown in the figure, for example, in an automatic lathe described later. It is possible to prevent chips from entering the space between the inner cylinder piece members 20 during the bar turning. However, the arrangement of the elastic connecting element 34 is not limited to this, and for example, the elastic connecting element 34 is locally installed at a desired portion in the space between the inner cylindrical piece members 20 to mutually connect the inner cylindrical piece members 20. You can also In addition, the elastic coupling element 34 can be configured not only by a liquid gasket but also by a combination of an elastic body such as a rubber plate and an adhesive.
[0024]
The elastic member 22 further includes an elastic intermediate cylinder 36 that is interposed between the outer cylinder portion 16 and each of the three inner cylinder piece members 20 and elastically supports the inner cylinder piece members 20 from the outside. As shown in FIGS. 1 and 4, the elastic intermediate cylinder 36 includes a substantially cylindrical outer surface 36 a that is in contact with the inner surfaces 24 b of the three vertical split pieces 24 of the outer cylinder portion 16, and an opposite side of the outer surface 36 a. The cylindrical member has a cylindrical inner surface 36b that is in contact with the outer surface 20a of the three inner cylindrical piece members 20. A plurality of (three in the illustrated embodiment) slits 38 that extend linearly in the axial direction along the outer surface 36a are formed in the elastic intermediate cylinder 36 at equal intervals in the circumferential direction. The slits 38 are formed in a radial shape apart from the inner surface 36b (that is, without opening to the inner surface 36b) while opening to the outer surface 36a over the entire axial length of the elastic intermediate cylinder 36. As a result, the elastic intermediate tube 36 has three arc-shaped wall portions 40 and three thin connecting portions 42 that integrally interconnect the arc-shaped wall portions 40 along the respective inner surfaces in the circumferential direction. It is formed. A single arcuate wall portion 40 is provided with a groove 44 extending in the axial direction along the outer surface thereof.
[0025]
In the elastic intermediate tube 36, when a radially inward pressing force is applied to the outer surface 36a, stress concentrates on the three connecting portions 42, and the connecting portions 42 are variously elastically deformed. Accordingly, the three arcuate wall portions 40 are displaced inward in the radial direction until the adjacent arcuate wall portions 40 come into contact with each other. Thereby, the inner surface 36b of the elastic intermediate cylinder 36 is distorted from the original cylindrical shape, and as a result, the substantial inner diameter dimension of the elastic intermediate cylinder 36 is reduced. When the pressing force to the outer surface 36a of the elastic intermediate tube 36 is released, each arcuate wall portion 40 returns to the initial position under the elastic restoring force of each connecting portion 42, and the inner diameter dimension of the elastic intermediate tube 36 is restored. To do.
[0026]
The elastic intermediate cylinder 36 applies the radially inward pressing force applied to each vertical split piece 24 of the outer cylinder portion 16 to the corresponding inner cylindrical piece member 20 located inside the vertical split piece 24 in the radial direction. Acts to ensure transmission. The elastic intermediate cylinder 36 supports the plurality of inner cylinder piece members 20 from the outside in the radial direction, thereby elastically holding the inner cylinder piece members 20 at positions where the cylindrical bar support surfaces 18 are formed. . Further, the elastic intermediate cylinder 36 receives pressure from the three vertically split pieces 24 and the three inner cylinder piece members 20 of the outer cylinder portion 16 so that the adjacent arc-shaped wall portions 40 come into contact with each other. In the range up to this point, each arcuate wall portion 40 itself has a flexibility that can be compressed and elastically deformed. As a suitable soft material for the elastic intermediate cylinder 36 that can exhibit such characteristics, for example, a resin material such as a fluororesin-based engineering plastic known as a trade name “Turkite B” as a bearing material or the like can be given. it can.
[0027]
The guide bush 10 is manufactured by separately manufacturing the various components described above and then assembling as follows. The bush main body integrally including the base portion 12 and the outer cylindrical portion 16 of the bar support portion 14 is manufactured from a desired metal material through a cutting process or the like. Therefore, each of the elastic intermediate cylinders 36 integrally molded from a resin material such as “Turkite B” through an injection molding process or the like so that the outer surface 36a is in close contact with the inner surface 24b of each vertical split piece 24 of the outer cylinder portion 16 While at least one of the vertically split piece 24 and the elastic intermediate cylinder 36 is elastically deformed, it is fitted inside the outer cylinder portion 16. At this time, each vertical split piece 24 of the outer cylinder portion 16 and each arc-shaped wall portion 40 of the elastic intermediate cylinder 36 are aligned with each other, and the rotation stopper 46 (FIG. 1) is provided protruding from the inner surface 24b of one vertical split piece 24. ) Is inserted into the groove 44 of the elastic intermediate cylinder 36. As a result, the elastic intermediate cylinder 36 has an elastic restoring force in which at least one of the elastic intermediate cylinder 36 and the outer cylinder portion 16 is generated at a predetermined position inside the outer cylinder portion 16 in a state where rotation with respect to the outer cylinder portion 16 is prevented. Held below.
[0028]
On the other hand, the three inner cylinder piece members 20 respectively molded from a hard material such as zirconia ceramics are joined into a cylindrical shape by the elastic connecting element 34 as described above to produce an inner cylinder structure. This inner cylinder structure is formed so that the outer surface 20a of each inner cylinder piece member 20 is in close contact with the inner surface 36b of the elastic intermediate cylinder 36 fitted into the outer cylinder portion 16, and the inner cylinder structure ( While at least one of the elastic connecting element 34) is elastically deformed, it is fitted inside the outer cylinder portion 16 and the elastic intermediate cylinder 36. At this time, each vertical split piece 24 of the outer cylindrical portion 16 and each arc-shaped wall portion 40 of the elastic intermediate cylinder 36 and each inner cylindrical piece member 20 of the inner cylindrical structure are aligned with each other, and one vertical split piece 24 is formed. A second detent 48 (FIG. 1) projecting from the inner surface 24 b is inserted into a groove 32 b formed in the flange portion 32 of one inner cylinder piece member 20. As a result, the inner cylinder structure and the outer cylinder part 16 are located at predetermined positions inside the outer cylinder part 16 and the elastic intermediate cylinder 36 in a state where all the inner cylinder piece members 20 are prevented from rotating with respect to the outer cylinder part 16. At least one of the cylindrical portions 16 is held under an elastic restoring force generated.
[0029]
When the guide bush 10 is properly assembled in this way, the three inner cylinder piece members 20 of the inner cylinder structure have the center axis 18a of the bar support surface 18 formed by them as the center axis of the bar support 14. 14a is maintained. Further, the engagement surface 32a of the flange portion 32 formed on each inner cylinder piece member 20 of the inner cylinder structure closely contacts the locking surface 30a of the claw 30 formed on each vertical split piece 24 of the outer cylinder portion 16. Each inner cylinder piece Material The 20 axial end faces 20 d are disposed on substantially the same plane adjacent to the open end face 16 a of the outer cylinder portion 16. In this state, the inner cylinder structure is prevented from unintentionally protruding outward from the outer cylinder part 16 from a predetermined position inside the outer cylinder part 16. Further, the elastic intermediate cylinder 36 is disposed so as to be substantially shielded by the flange portion 32 of each inner cylinder piece member 20 at a position away from the opening end surface 16 a of the outer cylinder portion 16. As a result, the elastic intermediate cylinder 36 made of a relatively soft material is isolated from the chips scattered during the turning process, so that the damage is prevented.
[0030]
In the guide bush 10, the vertical split pieces 24 of the outer cylindrical portion 16, the inner cylindrical piece members 20 of the inner cylindrical structure, and the arc-shaped wall portions 40 of the elastic intermediate cylinder 36 are arranged so as to be shifted from each other in the circumferential direction. Also good. Further, on the precondition that the outer cylinder portion 16, the inner cylinder structure and the elastic intermediate cylinder 36 can cause the desired elastic deformation, the vertical split piece 24 of the outer cylinder portion 16, the inner cylinder piece member 20 of the inner cylinder structure, The number of arc-shaped wall portions 40 of the elastic intermediate tube 36 may be different from each other, and may be various numbers other than three.
[0031]
In the guide bush 10 having the above-described configuration, when an external force inward in the radial direction is applied to the three vertically divided pieces 24 of the outer cylinder portion 16, each vertically divided piece 24 is elastically deformed and at the same time, The outer surface 36a of the elastic intermediate cylinder 36 that contacts the inner surface 24b is loaded with an external force radially inward from each longitudinally split piece 24. As a result, as described above, the elastic intermediate cylinder 36 is elastically deformed and its substantial inner diameter Dimensions are reduced. Along with this, the outer surface 20a of the three inner cylinder piece members 20 contacting the inner surface 36b of the elastic intermediate cylinder 36 is loaded with an external force radially inward from the elastic intermediate cylinder 36, and as a result, as described above, Under the elastic deformation of the elastic connecting element 34, the inner diameter dimension of the bar support surface 18 formed by the inner surface 20b of the inner cylindrical piece member 20 decreases. At the same time, a pressing force is directly applied to the engaging surface 32a of the flange portion 32 formed on each inner cylinder piece member 20 from the locking surface 30a of the claw 30 formed on each vertical split piece 24 of the outer cylinder portion 16. The inner diameter dimension of the bar support surface 18 is also reduced by this pressing force.
[0032]
From this state, when the radial external force to the vertical split pieces 24 of the outer cylinder portion 16 is weakened, the vertical split pieces 24 are elastically restored, and accordingly, the elastic intermediate cylinder 36 and the elastic connecting element 34 are elastically restored, The inner diameter dimension of the bar support surface 18 increases (restores). While the inner diameter dimension of the bar support surface 18 decreases and increases, the three inner cylindrical piece members 20 have the center axis 18a of the bar support surface 18 aligned with the center axis 14a of the bar support portion 14. It is displaced in the radial direction while maintaining the state. As described above, in the guide bush 10, the bar support surface 18 formed by the three inner cylindrical piece members 20 is adjusted by adjusting the external force, that is, the pressing force applied to the bar support portion 14 radially inward. The inner diameter can be adjusted.
[0033]
In the guide bush 10, the inner diameter dimension of the bar material support surface 18 formed by the three inner cylinder piece members 20 is the outer diameter dimension of the bar material to be supported (processed) while the guide bush 10 is in an inactive state. Is set to be larger than Then, before starting the actual processing operation in which the guide bush 10 is put into the working state, the target bar is inserted into the bar support 14 and the inner diameter of the bar support surface 18 is set to the outside of the bar as described above. By finely adjusting according to the diameter, a desired fine gap of the order of μm is obtained between the bar support surface 18 and the bar outer peripheral surface. The guide bush 10 is capable of centering and supporting the bar so that it can be fed in the axial direction by securing such a fine gap in the operating state.
[0034]
Here, when a drawn material with a low outer dimensional accuracy that has been drawn to a predetermined diameter is used as it is as a support (machining) target bar, the above-mentioned fine gap is formed in the minimum outer diameter portion of the bar. As described above, the inner diameter dimension of the bar support surface 18 is finely adjusted. If the friction between the bar support surface 18 and the outer peripheral surface of the bar increases due to the increase in the outer diameter of the bar while the bar supported by the guide bush 10 is fed in the axial direction in this operating state, the outer cylinder portion Since each vertical split piece 24 of 16 is in a state in which it cannot be displaced radially outward, each arcuate wall portion 40 of the elastic intermediate cylinder 36 receives pressure between the outer cylinder portion 16 and the inner cylinder structure, and is described above. It is elastically deformed. As a result, under the elastic deformation of the elastic connecting element 34 having the inner cylinder structure, each inner cylinder piece member 20 is displaced radially outward, and the inner diameter dimension of the bar support surface 18 matches the outer diameter dimension of the bar. Expand passively. In this way, the guide bush 10 can center and support a bar made of a drawn material so that it can be fed in the axial direction. In addition, at this time, since each inner cylinder piece member 20 is formed of a hard material, the wear resistance of the bar support surface 18 is remarkably improved, and the wear of each inner cylinder piece member 20 due to friction with the bar material. Can be suppressed as much as possible.
[0035]
In the guide bush 10 having the above-described configuration, the inner cylinder structure and the elastic intermediate cylinder 36 can be removed from the outer cylinder portion 16 as necessary by a procedure reverse to the assembly procedure described above. When the inner diameter dimension of the bar support portion 14 is changed in response to the change in the diameter dimension, the inner diameter structure of the bar support surface 18 may be replaced with another inner cylinder structure. Therefore, when machining different types of bar materials (round bar, square bar) with various outer diameters on an automatic lathe equipped with the guide bush 10, various types of inner diameters corresponding to these different bar types are available. By preparing the inner cylinder structure and replacing the inner cylinder structure with the bush body consisting of the base 12 and the outer cylinder portion 16 mounted on an automatic lathe, high-precision machining of different types of bars can be performed sequentially. . Even when the inner surface 20b of each inner cylinder piece member 20 is worn due to a long working operation, only the inner cylinder structure may be replaced as appropriate without replacing the bushing body. Here, according to the guide bush 10, the replacement frequency of the inner cylinder structure including the inner cylinder piece member 20 can be reduced by improving the wear resistance of the bar support surface 18.
[0036]
Next, with reference to FIG. 5, the structure of the main part of the automatic lathe 50 equipped with the guide bush 10 having the above structure will be described. The guide bush 10 is rotatably installed in a column 60 on the machine table in the vicinity of a machining work position by a tool 58 set on the lathe machine table via a sleeve member 52, a bearing device 54, and a flange member 56. The
[0037]
The guide bush 10 is accommodated in the front end (left end in the drawing) region of the sleeve member 52 so as to be slidable in the axial direction and not relatively rotatable. At the front end of the inner peripheral surface of the sleeve member 52, a pressure load surface 62 that can contact a plurality of pressure receiving surfaces 28a provided on the outer peripheral surface of the bar support 14 of the guide bush 10 is formed. In the rear end (right end in the figure) region of the sleeve member 52, an adjusting nut 64 having an internal thread portion that engages with the external thread portion 12c (FIG. 1) provided on the base portion 12 of the guide bush 10 is fixed in the axial direction. And can be rotated. Accordingly, when the adjustment nut 64 rotates, the guide bush 10 moves in the axial direction within the sleeve member 52.
[0038]
A driven gear 68 is attached to the rear end region of the outer peripheral surface of the sleeve member 52 via a key 66. The driven gear 68 is coupled to a guide bush drive source (not shown) via a power transmission mechanism (not shown), and is driven to rotate at the same rotational speed as the main shaft 70 installed behind the column 60 by the guide bush drive source. Is done. As a result, the driven gear 68, the adjusting nut 64, the sleeve member 52, and the guide bush 10 are integrally rotated inside the flange member 56 at the same rotational speed as that of the main shaft 70.
[0039]
The flange member 56 is fixed to the column 60 by bolts 72, for example. As described above, the guide bush 10, the sleeve member 52, the flange member 56, the adjustment nut 64, and the driven gear 68 can be attached to a predetermined position of the column 60 of the automatic lathe 50 as a pre-assembled rotary guide bush device. When the guide bush 10 is used as a fixed guide bush device, the bearing device 54, the driven gear 68, the guide bush drive source, and the like are omitted.
[0040]
The spindle 70 holds the bar W to be turned and is rotationally driven by a spindle driving source (not shown). The main shaft 70 is installed behind the column 60 so as to be movable in the axial direction so that the rotation axis of the guide bush 10 and the rotation axis of the main shaft 70 coincide with each other. In the front end region of the main shaft 70, an openable / closable chuck 74 capable of gripping the bar W is accommodated. The chuck 74 is a so-called collet chuck having a slit at the tip. When a radially inward external force, that is, a pressing force is applied to the slit, the rod gripping hole 76 at the tip is reduced in diameter, and the chuck 74 is chucked. 74 closes and the bar W is firmly and securely held. When the radial external force applied to the slot is released, the slot is restored, the rod gripping hole 76 is expanded, the chuck 74 is opened, and the rod W is released.
[0041]
Further, a hollow cylindrical actuating member 78 is accommodated in the main shaft 70 so as to be movable in the axial direction. The actuating member 78 accommodates the chuck 74 in its front end region, and moves forward in the axial direction (leftward in the figure) by a chuck drive source (not shown), thereby pushing the chuck 74 into the slit inward in the radial direction. Pressure is applied and the chuck 74 is closed. If the operation member 78 is moved rearward in the axial direction (rightward in the figure) from this state, the chuck 74 is opened. The configuration of the main shaft 70 is not limited to the above. For example, as a chuck opening / closing operation mechanism, it is also possible to adopt a configuration in which an operation member connected to the rear end of the chuck is moved axially rearward together with the chuck to apply a pressing force radially inward to the slit portion of the chuck. it can.
[0042]
In the automatic lathe 50 having the above-described configuration, when performing the processing operation of the bar W, first, the nominal inner diameter dimension corresponding to the outer diameter dimension of the bar W to be processed is formed on the outer cylinder portion 16 of the guide bush 10. And an appropriate elastic intermediate cylinder 36 are selected and attached to the sleeve member 52 mounted on the column 60. Next, the bar W gripped by the main shaft 70 is inserted into the bar support portion 16 from behind the guide bush 10 by moving the main shaft 70 in the axial direction without applying an external force radially inward to the outer cylinder portion 16. To do. From this state, the adjustment nut 64 is turned to move the guide bush 10 rearward in the axial direction, and the pressure receiving surface 28 a of the outer cylinder portion 16 is pressed against the pressure load surface 62 of the sleeve member 52. Thereby, the three vertically split pieces 24 (FIG. 1) of the outer cylinder portion 16 are elastically deformed, and the three inner cylinder piece members 20 are radially moved under the elastic deformation of the elastic intermediate cylinder 36 and the elastic connecting element 34. By displacing inward, a desired minute gap of the order of μm is formed between the bar support surface 18 and the outer peripheral surface of the bar W. After adjusting the inner diameter of the bar support surface 18 of the guide bush 10 in this manner, the guide bush 10 performs turning with, for example, the tool 58 while centering and supporting the vicinity of the processed portion of the bar W. .
[0043]
By the way, in the above-described guide bush 10, each arc-shaped wall portion 40 of the elastic intermediate tube 36 is connected to the outer tube portion 16 when the outer diameter of the rod is locally increased while the rod is fed in the axial direction. By being compressed between each inner cylinder piece member 20 and elastically deforming, the plurality of inner cylinder piece members 20 are displaced radially outward, and the inner diameter dimension of the bar support surface 18 is the outer diameter of the bar. It is designed to expand passively to fit the dimensions. If such an action of the elastic intermediate cylinder 36 is used, a fine gap of the order of μm is formed between the bar support surface 18 and the bar outer peripheral surface when adjusting the inner diameter of the bar support surface 18 described above. At least, it is possible to center and support the bar so that it can be fed in the axial direction by simply bringing the bar support surface 18 into contact with the outer peripheral surface of the bar.
[0044]
From such a viewpoint, the inner diameter dimension adjusting mechanism of the bar support surface of the guide bush can be omitted. FIG. 6 shows a guide bush 80 according to a second embodiment of the present invention having such a simplified configuration. The guide bush 80 has substantially the same configuration as that of the above-described guide bush 10 except for the configuration of the outer cylinder portion of the bar support portion. Omitted.
[0045]
The bar support portion 82 of the guide bush 80 includes an outer cylinder portion 84 integrally connected to the base portion 12, a plurality (three) of inner cylinder piece members 20 installed inside the outer cylinder portion 84, and And an elastic member 22 that elastically holds the inner cylinder piece member 20 at a position where the bar support surface 18 is formed inside the outer cylinder portion 84. The bar support part 82 has a center axis 82a that matches the center axis of the bar to be supported, and supports the bar centeringly. The outer cylinder portion 84 has a configuration in which the slit 26 in the outer cylinder portion 16 of the guide bush 10 described above is omitted, and has a cylindrical inner shape that defines a central axis line that matches the central axis line 82a of the bar support portion 82. A peripheral surface 84a is provided (FIG. 7). Therefore, the outer cylinder portion 84 cannot substantially elastically deform in the radial direction, and the inner diameter dimension of the inner peripheral surface 84a cannot be changed.
[0046]
The elastic intermediate cylinder 36 constituting the elastic member 22 has an outer surface 36a (FIG. 4) in contact with an inner peripheral surface 84a of the outer cylinder portion 84, and an inner surface 36b (FIG. 4) having three inner cylinder pieces. Abutting on the outer surface 20a of the member 20, it is disposed between the outer cylinder portion 84 and the inner cylinder piece member 20, and supports each inner cylinder piece member 20 from the outside in this state. The bar support part 82 having such a configuration cannot positively adjust the inner diameter dimension of the bar support surface 18 formed by the three inner cylinder piece members 20. On the other hand, in the bar support portion 82, when an external force radially outward is applied to the bar support surface 18, each arcuate wall portion 40 (FIG. 4) of the elastic intermediate tube 36 is connected to the outer tube portion 84. By compressing between each inner cylinder piece member 20 and elastically deforming, the inner cylinder piece member 20 is displaced radially outward, and the inner diameter dimension of the bar material support surface 18 is passively expanded. Can do.
[0047]
Therefore, when the guide bush 80 having the above-described configuration is mounted on the automatic lathe 50 described above, a bar having an outer diameter corresponding to the inner diameter of the bar support surface 18 is used as the bar bushing. In the state of being in contact with the outer peripheral surface of the material, it can be centered and supported so that it can be fed in the axial direction. Here, even when a drawn material having a low external dimensional accuracy is used as a bar, the inner diameter of the bar support surface 18 is passively set within the elastically deformable range of each arcuate wall portion 40 of the elastic intermediate cylinder 36. The bar can be centered and supported so that it can be fed in the axial direction.
[0048]
The guide bushes 10 and 80 described above have a configuration in which the plurality of inner cylinder piece members 20 installed on the bar material support portions 14 and 82 are connected to each other via the elastic connection element 34 so as to be relatively displaceable. . However, the guide bush which concerns on this invention can also have a bar | burr material support part arrange | positioned inside an outer cylinder part in the state which the some inner cylinder piece member isolate | separated mutually. FIG. 8 shows a guide bush 90 having such a configuration according to a third embodiment of the present invention. The guide bush 90 has substantially the same configuration as the above-described guide bush 10 except for the configuration of the inner cylinder piece member and the elastic member of the bar support portion, and therefore, corresponding components are denoted by common reference numerals. The description is omitted.
[0049]
The bar support portion 92 of the guide bush 90 is installed on the inner side of the outer cylinder portion 16 that is elastically deformable in the radial direction and is integrally connected to the base portion 12, and is formed of a hard material. And a plurality of (three) inner cylinder piece members 96 that cooperate with each other to form a substantially cylindrical rod material support surface 94, and the inner cylinder piece members 96 are arranged on the inner side of the outer cylinder portion 16. And an elastic member 98 that is elastically held at a position where the support surface 94 is formed. The bar support portion 92 has a center axis 92a that matches the center axis of the bar to be supported, and supports the bar centeringly.
[0050]
As shown in FIG. 9, each inner cylinder piece member 96 of the guide bush 90 has an arcuate outer surface 96 a that faces the inner surface 24 b (FIG. 2) of the corresponding vertical split piece 24 of the outer cylinder portion 16 via a gap. And an arcuate inner surface 96b opposite to the outer surface 96a, and a pair of side surfaces 96c extending between the outer surface 96a and the inner surface 96b. The three inner cylinder piece members 96 have their inner surfaces 96b substantially located on a common cylindrical surface, and their one side surfaces 96c are opposed to each other with a gap therebetween. Housed inside. In this state, the inner surface 96b of the inner cylindrical piece member 96 cooperates with each other to form a substantially cylindrical bar support surface 94 (having a central axis 94a) for centering and supporting the bar so that it can be axially fed. Form.
[0051]
Each inner cylinder piece member 96 has a flange portion 100 that protrudes radially outward, adjacent to one axial end surface 96d thereof. The flange portion 100 of each inner cylinder piece member 96 is formed with an engagement surface 100a extending in a taper shape toward one axial end surface 96d, and a groove 100b extending in the axial direction along its radially outer end surface. Engraved. Further, each inner cylinder piece member 96 is formed with an edge groove 102 having an acute cross section in a boundary region between the inner surface 96b thereof, the axial one end surface 96d and the axial other end surface 96e.
[0052]
Examples of the hard material that can be suitably used for each inner cylinder piece member 96 include engineering ceramics. In this case, it is advantageous to produce at least a portion including the inner surface 96b forming the rod support surface 94 from zirconia ceramics excellent in wear resistance, impact strength, and surface smoothness. According to such a configuration, the durability of the bar support surface 94 can be significantly improved.
[0053]
The elastic member 98 is interposed between the outer cylinder portion 16 and each of the three inner cylinder piece members 96, and the elastic intermediate cylinder 36 that elastically supports the inner cylinder piece members 96 from the outside, and three pieces. And a pair of elastic support elements 104 that are engaged with the inner cylinder piece member 96 and elastically support the inner cylinder piece member 96 from the inside. The elastic intermediate cylinder 36 is in contact with the inner surface 24b of the three vertical split pieces 24 of the outer cylinder portion 16 at its outer surface 36a (FIG. 4), and at the inner surface 36b (FIG. 4), It abuts on the outer surface 96 a of the tube piece member 96. The elastic intermediate cylinder 36 applies the radially inward pressing force applied to each vertical split piece 24 of the outer cylindrical portion 16 to the corresponding inner cylindrical piece member 96 located inside the vertical split piece 24 in the radial direction. Acts to ensure transmission. The elastic intermediate cylinder 36 supports the plurality of inner cylinder piece members 96 from the outside in the radial direction, thereby elastically holding the inner cylinder piece members 96 at a position where the cylindrical bar support surface 94 is formed. . Further, the elastic intermediate cylinder 36 receives pressure from both of the three vertically split pieces 24 and the three inner cylinder piece members 96 of the outer cylinder portion 16, and is adjacent to the arcuate wall portion 40 (FIG. 4). ) Until they come into contact with each other, each arcuate wall portion 40 itself is flexible enough to be compressed and elastically deformed.
[0054]
As shown in FIG. 10, each of the pair of elastic support elements 104 is formed of an annular spring formed by bending a spring wire into a C-ring shape. These elastic support elements 104 are each received by the pair of edge grooves 102 of each inner cylinder piece member 96 in a length region obtained by dividing the overall length into approximately three equal parts. It is elastically biased outward. Thereby, the elastic support elements 104 cooperate with each other to elastically hold the three inner cylinder piece members 96 at positions where the cylindrical bar support surfaces 94 are formed. Although each elastic support element 104 does not have a mechanical interconnection function between the inner cylindrical piece members 96, the outer surface 96a of the three inner cylindrical piece members 96 is loaded with a radially inward pressing force. In some cases, the elastic supporting element 104 is elastically deformed so as to reduce the radial dimension thereof. Accordingly, the three inner cylinder piece members 96 are displaced inward in the radial direction within a range until the opposing side faces 96c come into contact with each other, and as a result, a bar formed by the inner surfaces 96b of the inner cylinder piece members 96 The inner diameter dimension of the support surface 94 is reduced. When the pressing force to the outer surface 96 a of each inner cylinder piece member 96 is released, each inner cylinder piece member 96 returns to the initial position under the elastic restoring force of both elastic support elements 104, and the bar material support surface 94. The inner diameter of the is restored.
[0055]
The guide bush 90 is manufactured by separately assembling the various components described above and then assembling as follows. First, similarly to the assembly process of the guide bush 10 described above, the elastic intermediate cylinder 36 is assembled to the bush main body integrally including the base portion 12 and the outer cylinder portion 16 of the bar support portion 92. At this time, the rotation stopper 46 installed on one vertical split piece 24 of the outer cylinder portion 16 is inserted into the groove 44 (FIG. 4) of the elastic intermediate cylinder 36, thereby rotating the elastic intermediate cylinder 36 with respect to the outer cylinder portion 16. Stop. In addition, as shown in FIG. 11, the second detent 48 which protrudes from the inner surface 24b is installed in all the vertical split pieces 24 of the outer cylinder part 16. As shown in FIG.
[0056]
On the other hand, a pair of elastic support elements 104 are assembled as described above to the three inner cylinder piece members 96 each molded from a hard material such as zirconia ceramics to produce a substantially cylindrical inner cylinder structure. This inner cylinder structure is formed so that the outer surface 96a of each inner cylinder piece member 96 is in close contact with the inner surface 36b of the elastic intermediate cylinder 36 fitted into the outer cylinder portion 16, and the inner cylinder structure ( While at least one of the elastic support element 104) is elastically deformed, it is fitted inside the outer cylinder portion 16 and the elastic intermediate cylinder 36. At this time, each vertical split piece 24 and each arcuate wall portion 40 of the elastic intermediate cylinder 36 and each internal cylindrical piece member 96 of the inner cylindrical structure are aligned with each other and protruded from the inner surface 24b of each vertical split piece 24. The second detent 48 is inserted into the groove 100 b formed in the flange portion 100 of the corresponding inner cylinder piece member 96. As a result, the inner cylinder structure has the outer cylinder part 16 and the inner cylinder part 16 and the elastic intermediate cylinder 36 at predetermined positions inside the outer cylinder part 16 and the elastic intermediate cylinder 36 in a state where all the inner cylinder piece members 96 are prevented from rotating with respect to the outer cylinder part 16. At least one of the elastic intermediate cylinder 36 and the inner cylinder structure (elastic support element 104) is held under an elastic restoring force generated. Preferably, in this state, each elastic support element 104 is fixedly received and held in the edge groove 102 of the three inner cylindrical piece members 96 by its own elastic restoring force.
[0057]
When the guide bush 90 is properly assembled in this way, the three inner cylinder piece members 96 of the inner cylinder structure are such that the central axis 94a of the bar support surface 94 formed by them is the central axis of the bar support 92. It is held in a state that matches 92a. Further, the engagement surface 100a of the flange portion 100 formed on each inner cylinder piece member 96 of the inner cylinder structure is connected to the locking surface 30a (FIG. 11) of the claw 30 formed on each vertical split piece 24 of the outer cylinder portion 16. Each inner cylinder piece is in close contact Material 96 axial end faces 96d are disposed on substantially the same plane adjacent to the opening end face 16a (FIG. 11) of the outer cylinder portion 16. In this state, the inner cylinder structure is prevented from unintentionally protruding outward from the outer cylinder part 16 from a predetermined position inside the outer cylinder part 16. Further, the elastic intermediate cylinder 36 is disposed so as to be substantially shielded by the flange portion 100 of each inner cylinder piece member 96 at a position away from the opening end surface 16 a of the outer cylinder portion 16. As a result, the elastic intermediate cylinder 36 made of a relatively soft material is isolated from the chips scattered during the turning process, so that the damage is prevented.
[0058]
In the guide bush 90, the vertical split pieces 24 of the outer cylindrical portion 16, the inner cylindrical piece members 96 of the inner cylindrical structure, and the arc-shaped wall portions 40 of the elastic intermediate cylinder 36 are arranged so as to be shifted from each other in the circumferential direction. Also good. Moreover, on the precondition that the outer cylinder portion 16, the inner cylinder structure, and the elastic intermediate cylinder 36 can cause the desired elastic deformation, the vertical split piece 24 of the outer cylinder portion 16, the inner cylinder piece member 96 of the inner cylinder structure, The number of arc-shaped wall portions 40 of the elastic intermediate tube 36 may be different from each other, and may be various numbers other than three.
[0059]
The guide bush 90 having the above configuration operates in the same manner as the guide bush 10 described above. That is, when an external force inward in the radial direction is applied to the three vertical split pieces 24 of the outer cylinder portion 16, each vertical split piece 24 is elastically deformed, and at the same time, an elastic intermediate that contacts the inner surface 24 b of each vertical split piece 24. An external force radially inward from each vertical split piece 24 is applied to the outer surface 36a of the cylinder 36, whereby the elastic intermediate cylinder 36 is elastically deformed and its substantial inner diameter is reduced as described above. Along with this, the outer surface 96a of the three inner cylinder piece members 96 that contact the inner surface 36b of the elastic intermediate cylinder 36 is loaded with an external force radially inward from the elastic intermediate cylinder 36. As a result, as described above, Under the elastic deformation of the pair of elastic support elements 104, the inner diameter dimension of the bar support surface 94 formed by the inner surface 96b of the inner cylindrical piece member 96 decreases.
[0060]
From this state, when the radial external force applied to each vertical split piece 24 of the outer cylinder portion 16 is weakened, each vertical split piece 24 is elastically restored, and accordingly, the elastic intermediate cylinder 36 and both elastic support elements 104 are elastically restored. The inner diameter of the bar support surface 94 increases (restores). While the inner diameter dimension of the bar support surface 94 decreases and increases, the three inner cylindrical piece members 96 cause the center axis 94a of the bar support surface 94 to coincide with the center axis 92a of the bar support portion 92. It is displaced in the radial direction while maintaining the state. As described above, in the guide bush 90, the bar support surface 94 formed by the three inner cylinder piece members 96 is adjusted by adjusting the external force, that is, the pressing force applied to the bar support portion 92 in the radially inward direction. The inner diameter can be adjusted.
[0061]
In the guide bush 90, the inner diameter dimension of the bar support surface 94 formed by the three inner cylinder piece members 96 is the outer diameter dimension of the bar material to be supported (processed) while the guide bush 90 is in an inactive state. Is set to be larger than Then, before starting the actual processing operation in which the guide bush 90 is put into the working state, the target bar is inserted into the bar support 92, and the inner diameter of the bar support surface 94 is set to the outside of the bar as described above. By fine-tuning according to the diameter, a desired fine gap of the order of μm is obtained between the bar support surface 94 and the bar outer peripheral surface. The guide bush 90 can center and support the bar so that it can be fed in the axial direction by securing such a fine gap in the operating state.
[0062]
Here, when a drawn material with a low outer dimensional accuracy that has been drawn to a predetermined diameter is used as it is as a support (machining) target bar, the above-mentioned fine gap is formed in the minimum outer diameter portion of the bar. As described above, the inner diameter dimension of the bar support surface 94 is finely adjusted. If the friction between the bar support surface 94 and the bar outer peripheral surface increases due to an increase in the outer diameter of the bar while the bar supported by the guide bush 90 is fed in the axial direction in this action state, the outer cylinder portion Since each vertical split piece 24 of 16 is in a state in which it cannot be displaced radially outward, each arcuate wall portion 40 of the elastic intermediate cylinder 36 receives pressure between the outer cylinder portion 16 and the inner cylinder structure, and is described above. It is elastically deformed. As a result, each inner cylinder piece member 96 is displaced radially outward, and the inner diameter dimension of the bar support surface 94 is passively expanded in accordance with the outer diameter dimension of the bar. In this way, the guide bush 90 can center and support a bar made of a drawn material so that it can be fed in the axial direction. In addition, at this time, since each inner cylinder piece member 96 is formed of a hard material, the wear resistance of the bar support surface 94 is remarkably improved, and the wear of each inner cylinder piece member 96 due to friction with the bar material. Can be suppressed as much as possible.
[0063]
The elastic support element 104 incorporated in the guide bush 90 can be incorporated in the above-described guide bush 10 having the elastic coupling element 34. According to such a configuration, since the elastic action of the elastic member 22 in the guide bush 10 can be strengthened, the responsiveness of the radial displacement operation of the inner cylinder piece member 20 is improved, and the bar support portion 14 is more highly accurate. The centering support characteristic can be acquired. Further, when the plurality of inner cylinder piece members 20 are combined into a cylindrical shape by using the elastic connecting element 34 made of a liquid gasket, the elastic support element 104 is used even if the position accuracy of each inner cylinder piece member 20 is combined to be somewhat low. As a result, the positional accuracy of each inner cylinder piece member 20 can be obtained by the supporting action. Thereby, the manufacturing process of the guide bush 10 is simplified, and the work cost is reduced when the inner cylinder piece member 20 is replaced.
[0064]
【The invention's effect】
As is apparent from the above description, according to the present invention, the guide bush installed in the automatic lathe is provided with a multi-layered bar support portion, thereby changing the outer diameter of the bar to be processed and the bar. Not only can the wear of the material support surface be dealt with quickly, but also the wear resistance of the bar support surface can be significantly improved. Therefore, according to the present invention, it is possible to reduce as much as possible the influence of the wear of the guide bush, particularly the bar support surface, on the processing accuracy and manufacturing cost of the product in the automatic lathe, and when using a bar made of a drawn material. It will also be possible to produce high quality products.
[Brief description of the drawings]
FIGS. 1A and 1B are a cross-sectional view taken along line II of a guide bush according to a first embodiment of the present invention, and FIG.
2A is a cross-sectional view taken along line II-II, and FIG. 2B is an end view in the axial direction, of the base and the outer cylinder portion of the guide bush in FIG. 1;
3A is a cross-sectional view taken along line III-III, and FIG. 3B is an end view in the axial direction of the inner cylinder structure of the guide bush in FIG. 1;
4A is a cross-sectional view taken along line IV-IV of the elastic intermediate cylinder in the guide bush of FIG. 1, and FIG. 4B is an end view in the axial direction.
FIG. 5 is a cross-sectional view showing a main part of an automatic lathe equipped with the guide bush of FIG. 1;
6A is a cross-sectional view taken along line VI-VI and FIG. 6B is an end view in the axial direction of a guide bush according to a second embodiment of the present invention.
7A is a cross-sectional view taken along line VII-VII and FIG. 7B is an end view in the axial direction of the base portion and the outer cylinder portion of the guide bush shown in FIG. 6;
8A is a cross-sectional view taken along line VIII-VIII, and FIG. 8B is an axial end view of a guide bush according to a third embodiment of the present invention.
9A is a cross-sectional view taken along line IX-IX, and FIG. 9B is an end view in the axial direction, of a plurality of inner cylinder piece members in the guide bush in FIG. 8;
10 is a front view of an elastic support element in the guide bush of FIG. 8;
11A is a cross-sectional view taken along line XI-XI, and FIG. 11B is a cross-sectional view taken along line BB, of the base portion and the outer cylinder portion of the guide bush in FIG. 8;
[Explanation of symbols]
10, 80, 90 ... guide bush
12 ... Base
14, 82, 92 ... bar support
16, 84 ... outer cylinder part
18, 94 ... Bar support surface
20, 96 ... inner cylinder piece member
22, 98 ... elastic member
24 ... Vertical pieces
30 ... nail
34. Elastic connecting element
36 ... Elastic intermediate tube
50 ... Automatic lathe
70 ... Spindle
104. Elastic support element

Claims

In a guide bush comprising a hollow cylindrical base and a hollow cylindrical bar support provided adjacent to one axial end of the base,
The bar support part is
An outer cylinder part integrally connected to the base part;
A plurality of inner cylinder piece members that are installed inside the outer cylinder portion and are each formed of a hard material and cooperate with each other to form a cylindrical bar support surface;
An elastic member that elastically holds the plurality of inner cylinder piece members at a position where the bar support surface is formed inside the outer cylinder part so as to be independently displaceable from the outer cylinder part ; thing,
Guide bush characterized by

2. The guide bush according to claim 1, wherein the elastic member includes an elastic connecting element that is interposed between the adjacent inner cylinder piece members and elastically connects the inner cylinder piece members to each other.

The guide bush according to claim 2, wherein the elastic connecting element is formed of a liquid gasket.

The said elastic member is provided between the said outer cylinder part and each of these inner cylinder piece members, and is provided with the elastic intermediate cylinder which elastically supports these inner cylinder piece members from the outside. The guide bush according to any one of claims.

The guide bush according to claim 4, wherein the elastic intermediate cylinder is formed of a soft material that is compressed and elastically deformed by being compressed between the outer cylinder portion and the plurality of inner cylinder piece members.

The guide bush according to claim 1, wherein the elastic member includes an elastic support element that engages with the plurality of inner cylinder piece members and elastically supports the inner cylinder piece members from the inside. .

The guide bush according to claim 6, wherein the elastic support element is formed of a spring that elastically biases the plurality of inner cylinder piece members radially outward.

The guide bush according to any one of claims 1 to 7, wherein each of the plurality of inner cylindrical piece members is made of ceramics at least at a portion forming the bar support surface.

The outer cylinder part of the bar support part can be elastically deformed in the radial direction, and the inner diameter dimension of the bar support surface formed by the plurality of inner cylinder piece members changes with the elastic deformation of the outer cylinder part. The guide bush according to any one of claims 1 to 8.

An automatic lathe in which the guide bush according to any one of claims 1 to 9 is installed in the vicinity of a bar processing position.