JP2004160625A

JP2004160625A - Deep hole cutting tool

Info

Publication number: JP2004160625A
Application number: JP2002332125A
Authority: JP
Inventors: Takuji Nomura; 倬司野村
Original assignee: Unitac Inc
Current assignee: Unitac Inc
Priority date: 2002-11-15
Filing date: 2002-11-15
Publication date: 2004-06-10
Anticipated expiration: 2022-11-15
Also published as: JP4047703B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deep hole cutting tool applied to a gun drill system, for heightening cutting efficiency by forming a tool shank and a cutting head as separate members and enough securing the strength of a connecting part by screw engagement in the case of using the cutting head including a plurality of cutting blades to thereby improve performance of discharging chips using a coolant supplied through an intermediate inside. <P>SOLUTION: The outer peripheral surface of the cutting head 2 is provided with one discharge groove 6 linearly connected to a longitudinal discharge groove of the tool shank, a by-pass flow passage hole 7 extending from the tip part of the cutting head 2 though the inside of the head to the discharge groove 6 is formed thereon, and a plurality of cutting blades 9a to 9c are formed to be distributed, facing on the discharge groove 6 and a discharge port 7a on the by-pass flow passage hole 7 side, respectively. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、ガンドリルシステムに適用されるドリルの如き深穴切削具に関するものである。
【０００２】
【従来の技術】
深穴加工システムとして、ガンドリルシステム、ＢＴＡシステム、エジェクタシステムなどが知られているが、比較的小径の深穴加工には簡単な構成のガンドリルシステムが汎用されている。
【０００３】
ガンドリルシステムは、図１１に示すように、中空筒状で外面に長手方向に沿う断面Ｖ字状の凹溝を形成した工具シャンク３１の先端に、ドリルヘッド３２を一体的に固着したガンドリル３０を用い、その工具シャンク３１の中空部内をクーラントＣの供給通路３３、凹溝を切屑Ｓの排出溝３４とし、深穴加工時に、高圧のクーラントＣを供給通路３３を通してドリルヘッド３２の先端側より吐出させ、被加工物Ｗの切削穴Ｈ内で発生した切屑Ｔを当該クーラントＣと共に排出溝３４を通して外部に排出するように構成されている。しかして、このガンドリルシステムでは、小径でも排出溝３４のスペースを大きくとれることで、切屑Ｔを比較的容易に排出できる利点がある。
【０００４】
このようなガンドリル３０として、図１２に示す構成のものが一般的に知られている。その工具シャンク３１は、チャックなどに保持されて回転駆動力を受ける円筒状のドライバ部３１ａに、比較的薄肉のパイプ材の基端部を除くダイス成形によって外面に長手方向に沿う断面Ｖ字状の排出溝３４ａを形成した筒軸部３１ｂの基端部を嵌入固定した構造を備えている。また、ドリルヘッド３２は、鋼材の研削加工によって外周面に前記筒軸部３１ｂと同様の排出溝３４ｂが形成され、先端部に該排出溝３４ｂの一側面に臨んで切刃を形成する超硬チップ３５がロウ付けされると共に、内部に工具シャンク３１の供給通路３３ａに連通する供給通路３３ｂを有し、先端面に該供給通路３３ｂに連通する吐出口３６が開口している。なお、ドリルヘッド３２としては、全体が工具鋼からなって先端部に研削加工による切刃を形成したものや、超硬チップからなる切刃をねじ止めしたものも使用されている。そして、工具シャンク３１とドリルヘッド３２とは、筒軸部３１ｂのＶ字状をなす先端にドリルヘッド３２の山形基端部３２ａを嵌合し、この嵌合部でロウ付けすることによって一体化されている。
【０００５】
しかるに、上記の従来汎用のガンドリル３０では、ドリルヘッド３２の切刃の消耗や折損を生じた際に工具シャンク３１を含めて切削具全体を取り替える必要があってコスト高になる上、段取り替えにおいても長尺の切削具全体を交換するのに長時間を要して加工効率の低下を招き、また切刃の消耗に伴う再研磨作業も容易ではなく再研磨コストが高く付き、更にドリリングの他にリーミング行う場合は工具シャンク３１の先端にリーマヘッドを固着したリーマ専用工具が必要になって一層コスト高になるという問題があった。
【０００６】
そこで、本出願人は、先に特願２００２−２９５７８９において、中空内部をクーラント供給通路とし、外周面に長手方向に沿う断面Ｖ字状の排出溝を有する工具シャンクの先端に、切削ヘッドをねじ孔係合にて着脱可能に取り付けた深穴切削具を提案している。
【０００７】
この提案に係る深穴切削具では、例えば図８に示すように、工具シャンク２１は、円筒状のドライバ部２１ａにパイプ材からなるシャンク部２１ｂが基端側を嵌入固定され、その先端に中空筒状の被装着部２１ｃが一体的に設けられており、これらの全体にわたって連通する中空内部をクーラント供給通路２３ａとし、シャンク部２１ｂの基端部を除いて当該シャンク部２１ｂから被装着部２１ｃの先端までの外周面に長手方向に沿う断面Ｖ字状の排出溝２４ａを有すると共に、被装着部２１ｃの先端側に雌ねじ２７ａが形成されている。そして、切削ヘッド２２は、図９でも示すように、基端側に前記被装着部２１ｃの雌ねじ２７ａに螺合する雄ねじ２７ｂを備え、内部には被装着部２１ｃに螺合連結した状態で工具シャンク２１側のクーラント供給通路２３ａに連通する連通孔２３ｂを有すると共に、外周面には同じく螺合連結した状態で工具シャンク２１側の排出溝２４ａと直線的に繋がる断面Ｖ字状の凹溝２４ｂが雄ねじ２７ｂ部分を含めて全長に形成され、先端部には排出溝２４ｂの一側に臨んで設けられた切刃２５と前記連通孔２３ｂの開口部である吐出口２６とを備えている。
【０００８】
このような深穴切削具によれば、切刃２５の消耗や折損を生じた際、切削ヘッド２２のみを取り替えるだけで工具シャンク２１は継続使用できるから、切削ヘッドが一体型の切削具に比較して大幅なコスト低減が図れる上、段取り替えに際しても切削ヘッド２２のみをねじ込み交換するだけでよいため、簡単に短時間で作業を行えて生産効率が向上し、また切刃２５の消耗に伴う再研磨や交換の作業も切削ヘッド２２だけを取り外して容易に行え、ドリリリングとリーミングのように他の切削作業に切り換える場合にも、対応する種類の切削ヘッド２２…だけを用意しておけばよいので、備品コストを低減できると共に交換作業も短時間で容易に行えるという利点がある。
【０００９】
一方、比較的に大きな径の削孔に用いる油孔付き工具として、複数の切刃を備えたドリルが汎用されている。しかして、このような複数の切刃はドリル先端部の径方向の両側で互いに向きが逆になるように配置するため、ガンドリルシステムにおいて複数の切刃を備えた切削ヘッドを用いる場合、加工中の切屑を効率よく排出するために、前記の長手方向に沿う断面Ｖ字状の排出溝を工具シャンク及び切削ヘッドの径方向の両側に設けることになる。
【００１０】
【発明が解決しようとする課題】
しかしながら、前記提案の深穴切削具のように、工具シャンクと切削ヘッドとを別部材として両者をねじ係合にて連結する構成では、工具シャンク及び切削ヘッド径方向両側に排出溝を設けると、両側の排出溝によってねじ係合部におけるねじ部分が少なくなり、これによって両者の連結部の強度が非常に弱くなるため、切削負荷に耐えられなくなるという難点があった。
【００１１】
例えば、図１０はガンドリルシステムに適用する３つの切刃を有する切削ヘッドを工具シャンクとは別部材とする場合の仮定構成を示しており、（Ａ）はヘッド先端面、（Ｂ）は基端側のねじ係合部（雄ねじ部）の断面である。図示のように、切削ヘッド２２Ｐは、径方向両側に断面Ｖ字状をなす大小の排出溝２４Ｌ，２４Ｓを有しており、ヘッド先端部には、大きい排出溝２４Ｌの片側（ヘッド回転方向後方側）の側面に臨んで中央部切刃２５ａと周辺部切刃２５ｃが設けられると共に、小さい排出溝２５Ｓの同じく片側（ヘッド回転方向後方側）の側面に臨んで中間部切刃２５ｂが設けられ、両排出溝２５Ｌ，２５Ｓによる括れで分かたれた両側の略扇形の肉部２８ａ，２８ｂに各々クーラント供給孔２３が貫設され、各供給孔２３がヘッド先端面で吐出口２６として開口している。２９は肉部２８ａ，２８ｂの外周面に固着されたガイドパッドである。
【００１２】
しかして、このような切削ヘッド２２Ｓでは、基端側のねじ係合部における雄ねじ２７ｂの領域は、図１０（Ｂ）の如く、両排出溝２５Ｌ，２５Ｓによって切り欠かれて２つの円弧部に分離する上、その２つの円弧部を合わせても全周の１／２をやや上回る程度でしかなく、当然に対応する工具シャンク側のねじ係合部の雌ねじ（図示省略）の領域も同じになる。従って、当該切削ヘッド２２Ｓを工具シャンクにねじ係合で連結した深穴切削具では、両者の連結部の強度が非常に弱くなってしまい、切削負荷による連結部の折損、曲がりや捻じれ等の変形を生じ易くなる。
【００１３】
本発明は、上述の情況に鑑み、工具シャンクと切削ヘッドとを別部材として両者をねじ係合にて連結する構成において、該切削ヘッドに複数の切刃を備えたものを用いる場合に、工具シャンクと切削ヘッドと連結部の強度を充分に確保して、しかも切屑の排出性をよくして切削効率を高め得る深穴切削具を提供することを目的としている。
【００１４】
【課題を解決するための手段】
上記目的を達成するために、本発明の請求項１に係る深穴切削具は、中空内部をクーラント供給通路とし、外周面の長手方向に沿って形成した断面Ｖ字状の１本の排出溝を有する工具シャンクと、この工具シャンクの先端部に基端部をねじ係合にて同軸状に着脱可能に連結される切削ヘッドとを備え、前記切削ヘッドは、連結状態において前記工具シャンクのクーラント供給通路に連通するクーラント供給孔と、該工具シャンクの排出溝に直線的に連なる１本の排出溝と、この排出溝に対して径方向の略対向位置で先端面から外周面にわたって開口した排出口と、該排出口からヘッド内部を通って前記排出溝に至るバイパス流路孔とを備え、該切削ヘッドの先端部には、複数の切刃が前記排出溝と前記排出口とに各々臨んで分配形成されると共に、先端面に前記クーラント供給孔に連通する２つの吐出口が径方向の略対向位置に開口してなる構成を採用したものである。
【００１５】
上記構成の深穴切削具によれば、工具シャンク及び切削ヘッドの外周面に長手方向に沿って形成される断面Ｖ字状の排出溝が１本であるため、両者のねじ係合部の雄ねじ及び雌ねじの領域は、該排出溝によって周方向の１箇所で切り欠かれるだけで、略３／４にわたって周方向に連続した形になる。従って、工具シャンクと切削ヘッドのねじ係合による連結部は、切削負荷に耐える充分な強度が付与され、加工中の折損、曲がりや捻じれ等の変形を生じ難くなる。しかして、前記排出溝は１本であり、この排出溝に臨む一側の切刃によって切削された切屑は、先端の吐出口から吐出されるクーラントに伴ってそのまま当該排出溝を通って排出されるが、他側の切刃によって切削された切屑も、吐出口から吐出されるクーラントと共にバイパス流路を通って該排出溝に流入し、当該排出溝を通って排出され、もって切屑の良好な排出性に基づく高い切削効率が得られる。
【００１６】
このような構成において、前記切削ヘッドの先端面に、前記排出溝の先端開放部とそのヘッド回転方向前方側に位置する吐出口との間、ならびに前記排出口とそのヘッド回転方向前方側に位置する吐出口との間に、それぞれクーラント誘導凹所を形成すれば、ヘッド先端部で吐出されるクーラントを排出溝とバイパス流路孔とに偏りなく分配できるから、各々に臨む切刃より発生する切屑を共に効率よく排出できる。
【００１７】
また、前記切削ヘッドが中央部切刃及び周辺部切刃と中間部切刃の３つの切刃を有する構成では、前記排出溝側に中央部切刃及び周辺部切刃を、前記バイパス流路孔側に中間部切刃を、それぞれ配置させることが推奨される。これは、切屑がヘッド先端の排出溝側では直接に当該排出溝に流入するのに対し、バイパス流路孔側では曲がった流路を経て該排出溝に合流するため、両者間で流通抵抗による排出性の差があり、切屑発生量が多くなる方を排出性の高い排出溝側とするのが好ましいことによる。
【００１８】
しかして、前記工具シャンクは、回転駆動力を受けるドライバ部を備えた工具シャンク本体と、この工具シャンク本体の先端部に一端側をねじ係合して同軸状に着脱可能に連結される連結用シャンク軸とで構成し、該連結用シャンク軸の他端側に前記切削ヘッドに対するねじ係合部を有するものとしてもよい。このように工具シャンクを分割構成とすれば、連結用シャンク軸として長さの異なるものを着脱交換することにより、削孔深さに対応した適正なシャンク長さを選択できると共に、連結用シャンク軸の経時的を損耗、加工中の突発的な折損や変形等を生じた際に、該連結用シャンク軸のみを交換すればよく、工具シャンク本体は継続使用できることになる。
【００１９】
また、上記のように工具シャンクを分割構成とする場合に、工具シャンク本体と連結用シャンク軸とのねじ係合部を、連結用シャンク軸と切削ヘッドとのねじ係合部と同一寸法形状に設定すれば、必要に応じて複数本の連結用シャンク軸を連結したり、連結用シャンク軸を介さずに工具シャンク本体に対して切削ヘッドを直接に連結して所用の切削加工を施すことが可能となる。
【００２０】
一方、ねじ係合部の雌ねじと雄ねじを角ねじにて構成すれば、結合強度が大きくなると共に、隙間を生じにくいためにねじ係合部からのクーラントの漏れを防止できる。
【００２１】
更に、ねじ係合部における雌ねじの奥端部に、ねじ切り用のぬすみ部を埋める埋込部材を配置し、この埋込部材に雄ねじの端面が密接するように構成すれば、部材製作の際にねじ切りを容易に行うためにぬすみ部が生じても、そのぬすみ部が埋められて隙間を生じないので、隙間に切屑が引っ掛かって円滑に排出できないというような不具合の発生を防止できる。
【００２２】
【発明の実施の形態】
以下に本発明に係る深穴切削具の好適実施形態について、図面を参照して具体的に説明する。図１〜図４は第一実施形態のガンドリル、図５〜図７は第二実施形態のガンドリルをそれぞれ示す。
【００２３】
第一実施形態のガンドリルは、図１（Ａ）〜（Ｃ）に示すように、工具シャンク１と、その先端に基端部をねじ係合して同軸状に着脱可能に連結された切削ヘッド３とで構成されている。
【００２４】
工具シャンク１は、チャックなどに保持されて回転駆動力を受ける円筒状のドライバ部１０ａと、このドライバ部１０ａに基端側を嵌入固定した略丸軸状のシャンク部１０ｂとで構成されている。このシャンク部１０ｂは、パイプ材の先端に筒状部材をＶ字カットで突き合わせて溶接固着したものであり、外周面には基端側を除いて長手方向に沿う断面Ｖ字状の排出溝３が先端まで形成されると共に、先端側には有底の接続筒部１ａが設けてあり、この接続筒部１ａの内奥側に角ねじにて構成される雌ねじ４ａが刻設されている。しかして、排出溝３は、シャンク部１０ｂの略中心から略９０°の開きをなす扇形で、パイプ材にはダイス成形によって形成されており、接続筒部１ａにおいては周側壁の略１／４を切り欠く形になっている。また、工具シャンク１には、各構成部材の中空部の連通により、ドライバ部１０ａの基端から接続筒部１ａの内底に至るクーラント供給通路５が排出溝３には開口しない状態で形成されている。
【００２５】
切削ヘッド２は、図２（Ａ）〜（Ｃ）で詳細に示すように、基端側が工具シャンク１の接続筒部１ａ内に密に嵌入し得る外径の接続軸部２ａをなし、この接続軸部２ａの先端側に前記接続筒部１ａの雌ねじ４ａに螺合する角ねじからなる雄ねじ４ｂが刻設されると共に、外周面には該接続軸部２ａを含む全長にわたって長手方向に沿う断面Ｖ字状の１本の排出溝６が形成される一方、先端側の該排出溝６とは径方向で略対向する位置に、先端面２ｂから外周面にわたって開口した排出口７ａを有し、該排出口７ａからヘッド内部を通って前記排出溝６に至るバイパス流路孔７が形成されている。７ｂは該バイパス流路孔７の排出溝５に開口した合流口である。また、切削ヘッド２の内部には、接続軸部２ａの端面から当該切削ヘッド２の先端面２ｂに至る２本のクーラント供給孔８ａ，８ｂが、排出溝６及びバイパス流路孔７を避けて、且つ径方向に略対向する配置で穿設されている。
【００２６】
しかして、該切削ヘッド２の先端部には、超硬チップからなる中央部切刃９ａと周辺部切刃９ｂとが排出溝６のヘッド回転方向後方側の側面に臨んでねじ止めされると共に、同じく超硬チップからなる周辺部切刃９ｃが排出口７ａに臨んで且つ中央部切刃９ａ及び周辺部切刃９ｂとは逆向きになる配置でねじ止めされ、また排出溝６及び排出口７ａを外れた外周部の二箇所にガイドパッド１３が固着されている。更に、先端面２ｂには、両クーラント供給孔８ａ，８ｂの開口部である吐出口８０ａ，８０ｂを有し、排出溝６の先端開放部６ａとそのヘッド回転方向前方側に位置する吐出口８０ａとの間、ならびに前記排出口７ａとそのヘッド回転方向前方側に位置する吐出口８０ｂとの間に、それぞれクーラント誘導凹所８１が形成されている。なお、排出溝６に対応するクーラント供給孔８ａとその吐出口８０ａは、排出口７ａに対応するクーラント供給孔８ｂとその吐出口８０ｂよりも径を大きくしている。
【００２７】
工具シャンク１と切削ヘッド２とは、図１に示すように、両者の連結状態、つまり工具シャンク１の接続筒部１ａに切削ヘッド２の接続軸部２ａを一杯に嵌入螺合して、接続軸部２ａの基部側の段部２ｃが接続筒部１ａの端面に密接した状態で、両者１，２の排出溝３，６同士がずれなく直線的に連なると共に、前者１のクーラント供給通路５と後者のクーラント供給孔８ａ，８ｂとが連通するように設定されている。なお、工具シャンク１の接続筒部１ａにおける端面と雌ねじ４ａとの間、ならびに切削ヘッド２の接続軸部２ａにおける基部側の段部２ｃと雄ねじ４ｂとの間は、同一長さで且つ略同じ内外径のパイロット部として、接続筒部１ａに接続軸部２ａが円滑に嵌入して正確に同芯状態に螺合できるように構成されている。
【００２８】
また、工具シャンク１の接続筒部１ａにおける雌ねじ４ａの奥端は、これに螺入する切削ヘッド２の接続軸部２ａの雄ねじ４ｂの端面が密接状態で当接して隙間が生じないように軸芯に垂直な平坦面に形成されている。このように雌ねじ４ａの奥端が平坦面になるようにねじ切り加工するのは実際には困難であるため、具体的には、図１に示すように、雌ねじ４ａの奥端部に、ねじ切り用のぬすみ部を埋める金属片から成る埋込部材１４を配置し、ロウ付け等にて一体固着している。
【００２９】
上記構成のガンドリルでは、工具シャンク１及び切削ヘッド２の外周面に長手方向に沿って形成される断面Ｖ字状の排出溝３，６が１本であるため、両者のねじ係合部の雌ねじ４ａ及び雄ねじ４ｂの領域は、該排出溝３，６によって周方向の１箇所で切り欠かれるだけで、略３／４にわたって周方向に連続した形になる。従って、工具シャンク１と切削ヘッド２のねじ係合による連結部は、切削負荷に耐える充分な強度を具備し、加工中の折損、曲がりや捻じれ等の変形を生じ難くなる。しかして、切削ヘッド２の排出溝６は１本であるが、中央部切刃９ａ及び周辺部切刃９ｂによって切削された切屑は、先端の吐出口８０ａから吐出されるクーラントに伴ってそのまま当該排出溝６と工具シャンク１の排出溝３とを通って排出される一方、中間部切刃９ｂによって切削された切屑も、吐出口８０ｂから吐出されるクーラントと共に排出口７ａよりバイパス流路７を通って、合流口７ｂより該排出溝６に流入し、当該排出溝６と工具シャンク１の排出溝３とを通って排出される。従って、このガンドリルによれば、切屑の良好な排出性に基づく高い切削効率が得られる。
【００３０】
また、この実施形態では、切削ヘッド２の先端面２ｂに、吐出口８０ａ，８０ｂから排出溝６と排出口７ａに至るクーラント誘導凹所８１が形成されていることから、ヘッド先端部で吐出されるクーラントを排出溝６とバイパス流路孔７とに偏りなく分配でき、これによって各々に臨む切刃９ａ〜９ｃより発生する切屑を共に効率よく排出できる。更に、排出溝６側に中央部切刃９ａ及び周辺部切刃９ｃが臨み、排出口７ａ側つまりバイパス流路孔７側に中間部切刃９ｂが臨んでいるから、中央部切刃９ａと周辺部切刃９ｃから多量に発生する切屑が直接に排出溝６に流入する一方、曲がった流路き流通抵抗で排出性に劣るバイパス流路孔７側には中間部切刃９ｂによる比較的少量の切屑が流入することになり、排出溝６とバイパス流路孔７との排出性の差に対応して流入する切屑量のバランスがとれ、もって全体として高い切屑排出性が確保される。
【００３１】
更に、本実施形態では、工具シャンク１と切削ヘッド２とのねじ係合部における雌ねじ４ａ及び雄ねじ４ｂを角ねじにて構成しているので、高い結合強度が得られると共に、螺合部に隙間が生じ難いため、ねじ係合部からのクーラントの漏れが防止される。また、雌ねじ４ａの奥端部に雄ねじ４ｂの先端面が密接するように、ねじ切り用のぬすみ部を埋める埋込部材１４を配置しているので、ねじ切りを容易に行うためにぬすみ部が生じても、そのぬすみ部が埋められて隙間を生じず、クーラントの漏れがより確実に防止される。なお又、工具シャンク１の雌ねじ４ａの開口端側と、切削ヘッド２の雄ねじ５ｂの末端側において、雌雄ねじ４ａ，５ｂの不完全ねじ部を排出溝３，６の両側面で完全なねじ断面形状でねじ端が終了し、排出溝３，６に臨むねじ端で隙間が生じないようになっている。
【００３２】
一方、このガンドリルでは、工具シャンク１に対して切削ヘッド２が着脱自在であるから、該切削ヘッド２の切刃９ａ〜９ｃの消耗や折損を生じた際は、該切削ヘッド２のみを取り替えるだけでよく、工具シャンク１をそのまま継続使用でき、段取り替えに際しても該切削ヘッド２のみをねじ込み交換するだけでよいため、簡単に短時間で作業を行えて生産効率が向上し、また切刃９ａ〜９ｃの消耗に伴う交換についても切削ヘッド２だけを取り外して単独で取り扱えるから、それらの作業を容易に行え、更にドリリリングとリーミングのように他の切削作業に切り換える場合にも、対応する種類の切削ヘッドだけを用意しておけばよいので、備品コストを低減できると共に交換作業も短時間で容易に行える。
【００３３】
第二実施形態のガンドリルは、図５（Ａ）に示すように、工具シャンク１が工具シャンク本体１１と連結用シャンク軸１２とに分割構成されている。しかるに、切削ヘッド２については、前記第一実施形態のガンドリルと同様構成であるため、各構成部分に第一実施形態と同じ符号を付して、その説明を省略する。
【００３４】
工具シャンク本体１１は、図６（Ａ）〜（Ｃ）で詳細に示すように、チャックなどに保持されて回転駆動力を受ける太径のドライバ部１１ａの先端側に、細径丸軸状の基部シャンク１１ｂが同軸状に一体形成されており、基部シャンク１１ｂの外周面には基端側を除いて断面Ｖ字状の排出溝３ａが長手方向に沿って先端まで形成されると共に、基部シャンク１１ｂの先端側には前記第一実施形態の工具シャンク１における接続筒部１ａと同様の接続筒部１ｂが設けてあり、この接続筒部１ｂの内奥側に角ねじにて構成される雌ねじ４ａが刻設されている。しかして、排出溝３ａは、図６（Ｂ），（Ｃ）に示すように、基部シャンク１１ｂの略中心から略９０°の開きをなす扇形で、基部シャンク１１ｂの円形断面の略１／４を欠いた形になっており、接続筒部１ｂでは周側壁を切り欠いている。また、ドライバ部１１ａには基端から中間位置に達する中心孔５０が形成され、この中心孔５０の内底から基部シャンク１１の接続筒部１ａの内底に至る２本のクーラント供給通路５ａ，５ａが排出溝３ａを避けて穿設されている。
【００３５】
連結用シャンク軸１２は、工具シャンク本体１１の基部シャンク１１ｂと同一外径の丸軸状であり、図７（Ａ）〜（Ｃ）で詳細に示すように、その一端側には該工具シャンク本体１１の接続筒部１ｂ内に密に嵌入し得る外径の接続軸部１２ａを有し、この接続軸部１２ａの先端側に前記接続筒部１ｂの雌ねじ４ａに螺合する角ねじからなる雄ねじ４ｂが刻設されると共に、他端側には工具シャンク本体１１の接続筒部１ｂと同一寸法形状で内奥に角ねじからなる雌ねじ４ａを刻設した接続筒部１２ｂが形成されている。また、この連結用シャンク軸１２の外周面には、長手方向に沿う断面Ｖ字状の排出溝３ｂが接続軸部１２ａ及び接続筒部１２ｂの部分を含む全長にわたって形成され、また該連結用シャンク軸１２の内部には、接続軸部１２ａの端面から接続筒部１２ｂの内底に至る２本のクーラント供給通路５ｂ，５ｂが排出溝３ｂを避けて穿設されている。
【００３６】
しかして、工具シャンク本体１１と連結用シャンク軸１２とは、図５（Ａ），（Ｃ）に示すように、両者の連結状態、つまり工具シャンク本体１１の接続筒部１ｂに連結用シャンク軸１２の接続軸部１２ａを一杯に嵌入螺合して、接続軸部１２ａの基部側の段部１２ｃが接続筒部１ｂの端面に密接した状態で、両者の排出溝３ａ，３ｂ同士がずれなく直線的に連なると共に、前者のクーラント供給通路５ａ，５ａと後者のクーラント供給通路５ｂ，５ｂとが連通するように設定されている。また、連結用シャンク軸１２と切削ヘッド２の接続軸部１２ａ，２ａは同一寸法形状であり、図５（Ａ），（Ｂ）に示すように、切削ヘッド２の接続軸部２ａを連結用シャンク軸１２の接続筒部１２ｂに一杯に嵌入螺合して、接続軸部２ａの基部側の段部２ｃが接続筒部１２ｂの端面に密接した状態で、排出溝６が連結用シャンク軸１２の排出溝３ｂにずれなく直線的に連なると共に、クーラント供給通路８ａ，８ｂが連結用シャンク軸１２のクーラント供給孔５ｂ，５ｂに連通するように設定されている。
【００３７】
工具シャンク本体１１及び連結用シャンク軸１２の接続筒部１ｂ，１２ｂにおける雌ねじ４ａの奥端には、前記第一実施形態ちおける工具シャンク１の接続筒部１ａと同様に、ねじ切り用のぬすみ部を埋める金属片から成る埋込部材１４を配置してロウ付け等にて一体固着している。また、連結用シャンク軸１２及び切削ヘッド２の接続軸部１２ａ，２ａにおける基部側の段部１２ｃ，２ｃと雄ねじ５ｂとの間、ならびにこれらに各々対応する工具シャンク本体１１及び連結用シャンク軸１２の接続筒部１ｂ，１２ｂにおける端面と雌ねじ５ａとの間は、同一長さで且つ略同じ内外径のパイロット部として、接続筒部１ｂ，２ｂに接続軸部１２ａ，２ａが円滑に嵌入して正確に同芯状態に螺合できるように構成されている。
【００３８】
上記第二実施形態のガンドリルによれば、切削ヘッド２での良好な切屑の排出性によって高い切削効率が得られることと、切削ヘッド２と連結用シャンク軸１２とのねじ係合による連結部に充分な強度を確保できることは前記第一実施形態と同様であるが、これに加えて、工具シャンク１が工具シャンク本体１１と独立部材である連結用シャンク軸１２とから構成されているから、連結用シャンク軸１２として異なる複数本の連結用シャンク軸２…を用意しておけば、その交換によってシャンク長さを変更でき、もって同じ工具シャンク本体１１を用いて適用する削孔深さに応じた適正なシャンク長さに設定できるという利点がある。従って、シャンク長さが数段階に異なる複数種の深穴切削具を用意する場合に比較して、備品コストが大幅に低減される。また、経時的なシャンク側の損耗、ならびに使用中におけるシャンク側の突発的な折損や変形の殆どは、切削負荷による捩れ応力が集中し易いシャンク中間部で生起するが、上記構成のガンドリルでは、該捩れ応力の集中部分が概して連結用シャンク軸２になるため、傷んだ連結用シャンク軸１２のみを新品と交換することにより、傷みにくいが構造的及びサイズ的に製作コストの高い工具シャンク本体１１を長期にわたって継続使用でき、これによって保全コストも大きく低減できる。
【００３９】
更に、本実施形態のガンドリルにあっては、連結用シャンク軸１２の一端側が雄ねじ４ｂを有する接続軸部１２ａ、他端側が雌ねじ４ａを有する接続筒部１２ｂを構成し、工具シャンク本体１１と該連結用シャンク軸１２の接続筒部１ｂ，１２ｂ、ならびに該連結用シャンク軸１２と切削ヘッド２の接続軸部１２ａ，２ａが同一寸法形状に設定されているから、複数本の連結用シャンク軸１２…を直線状に連結したり、連結用シャンク軸１２を介さずに工具シャンク本体１１に対して切削ヘッド２を直接に連結することも可能であり、複数本の連結用シャンク軸１２…の連結によって極端に長い削孔にも対応できる一方、逆に工具シャンク本体１１への切削ヘッド２の直接連結によって比較的に短い削孔にも対応できる。
【００４０】
一方、切削ヘッド２の切刃９ａ〜９ｃの消耗や折損を生じたり、段取り替えを行う場合は、前記第一実施形態と同様に該切削ヘッド２のみを取り替えるだけでよく、工具シャンク本体１１及び連結用シャンク軸１２をそのまま継続使用でき、簡単に短時間で作業を行えて生産効率が向上する。また、本実施形態でも、連結用シャンク軸１２と工具シャンク本体１１及び切削ヘッド２との各ねじ係合部における雌ねじ４ａ及び雄ねじ４ｂを角ねじにて構成しているので、高い結合強度が得られると共に、螺合部に隙間が生じ難いため、ねじ係合部からのクーラントの漏れが防止される。また、雌ねじ４ａの奥端部に雄ねじ４ｂの先端面が密接するように、ねじ切り用のぬすみ部を埋める埋込部材１４を配置しているので、クーラントの漏れがより確実に防止される。
【００４１】
なお、上記第一及び第二実施形態では工具シャンク１及び工具シャンク本体１１のねじ係合部を雌ねじ４ａとしているが、逆に該ねじ係合部を雄ねじ４ｂとし、これに対応して切削ヘッド２及び連結用シャンク軸１２の一端側のねじ係合部を雌ねじ４ａとすることも可能である。排出孔３，３ａ，３ｂ，５については、Ｖ字状断面の開き角が９０°のものを例示したが、略９０°〜１３０°の範囲の適当な開き角に設定することができ、また各部材１，１１，１２，２の中心側の肉部増加による強度向上を図るために底部をアール状としもよい。一方、切削ヘッドとしては、実施形態のように３つ切刃９ａ〜９ｃを有するもの以外に、２つあるいは４つ以上の切刃を有するものでもよく、また切刃の超硬チップをロウ付けしたり、切削ヘッド全体を工具鋼にて構成してその先端に切刃を直接形成したものも使用可能である。
【００４２】
【発明の効果】
請求項１の発明によれば、ガンドリルシステムを適用する工具シャンクと切削ヘッドとを別部材として両者をねじ係合にて連結する構成において、該切削ヘッドに複数の切刃を備えたものを用いる深穴切削具として、工具シャンク及び切削ヘッドの外周面に工具シャンクの排出溝に直線的に連なる１本の排出溝を設けると共に、切削ヘッドには先端部からヘッド内部を通って前記排出溝に至るバイパス流路孔を設け、複数の切刃を前記排出溝とバイパス流路孔側の排出口とに各々臨んで分配形成していることから、工具シャンクと切削ヘッドと連結部の強度を充分に確保して、しかもクーラントによる切屑の排出性をよくして切削効率を高め得るものが提供される。
【００４３】
請求項２の発明によれば、上記の深穴切削具において、切削ヘッドの先端面に、前記排出溝の先端開放部とそのヘッド回転方向前方側に位置するクーラントの吐出口との間、ならびに前記排出口とそのヘッド回転方向前方側に位置する同吐出口との間に、それぞれクーラント誘導凹所を形成していることから、ヘッド先端部で吐出されるクーラントを排出溝とバイパス流路孔とに偏りなく分配でき、もって各々に臨む切刃より発生する切屑を共に効率よく排出できる。
【００４４】
請求項３の発明によれば、切削ヘッドに中央部切刃及び周辺部切刃と中間部切刃の３つの切刃を有する上記の深穴切削具において、該切削ヘッドの前記排出溝側に中央部切刃及び周辺部切刃を、前記バイパス流路孔側に中間部切刃を、それぞれ配置させることから、排出溝とバイパス流路孔との排出性の差に対応して流入する切屑量のバランスがとれ、全体として高い切屑排出性が確保される。
【００４５】
請求項４の発明によれば、上記の深穴切削具において、工具シャンクを、工具シャンク本体と、その先端部にねじ係合して同軸状に着脱可能に連結される連結用シャンク軸とで構成し、該連結用シャンク軸の他端側に前記切削ヘッドに対するねじ係合部を有する構成としているから、連結用シャンク軸として長さの異なるものを着脱交換することにより、削孔深さに対応した適正なシャンク長さを選択でき、シャンク長さの異なる工具シャンクを用意する場合に比較して備品コストが大幅に低減すると共に、連結用シャンク軸の経時的を損耗、加工中の突発的な折損や変形等を生じた際に、該連結用シャンク軸のみを交換して工具シャンク本体は継続使用できるから、工具シャンク全体を新品と交換する場合に比較して保全コストを大きく低減できる。
【００４６】
請求項５の発明によれば、工具シャンクが工具シャンク本体と連結用シャンク軸とに分割構成された上記の深穴切削具において、工具シャンク本体と連結用シャンク軸とのねじ係合部を、連結用シャンク軸と切削ヘッドとのねじ係合部と同一寸法形状に設定していることから、複数本の連結用シャンク軸を直線状に連結して極端に長い削孔にも対応できる一方、逆に連結用シャンク軸を介さずに工具シャンク本体に対してドリルヘッドを直接に連結して比較的に短い削孔にも対応できる。
【００４７】
請求項６の発明によれば、上記の深穴切削具において、ねじ係合部の雌ねじと雄ねじを角ねじにて構成しているから、高い結合強度が得られると共に、螺合部に隙間が生じ難いため、ねじ係合部からのクーラントの漏れが防止されるという利点がある。
【００４８】
請求項７の発明によれば、上記の深穴切削具において、ねじ係合部における雌ねじの奥端部に、ねじ切り用のぬすみ部を埋める埋込部材を配置し、この埋込部材に雄ねじの端面が密接するように構成していることから、部材製作の際にねじ切りを容易に行うためにぬすみ部が生じても、そのぬすみ部が埋められて隙間を生じないので、隙間に切屑が引っ掛かって円滑に排出できないというような不具合の発生を防止できる。
【図面の簡単な説明】
【図１】本発明の第一実施形態に係るガンドリルの全体構成を示す部分省略正面図である。
【図２】同第一実施形態のガンドリルに用いる切削ヘッドを示し、（Ａ）は全体の正面図、（Ｂ）は先端から見た側面図、（Ｃ）は（Ａ）のＣ−Ｃ線の矢視断面図である。
【図３】同切削ヘッドにおける図２（Ｂ）のＩＩＩ −ＩＩＩ線の矢視断面図である。
【図４】同切削ヘッドの図２（Ａ）とは反対側から見た背面図である。
【図５】本発明の第二実施形態に係るガンドリルを示し、（Ａ）は全体構成を示す部分省略正面図、（Ｂ）は（Ａ）の仮想線円Ｂ内の拡大図、（Ｃ）は（Ａ）の仮想線円Ｃ内の拡大図である。
【図６】同第二実施形態のガンドリルに用いる工具シャンク本体を示し、（Ａ）は全体構成を示す部分省略正面図、（Ｂ）は先端から見た側面図、（Ｃ）は（Ａ）のＣ−Ｃ線の矢視断面図である。
【図７】同第二実施形態のガンドリルに用いる連結用シャンク軸を示し、（Ａ）は全体構成を示す部分省略正面図、（Ｂ）は先端から見た側面図、（Ｃ）は（Ａ）のＣ−Ｃ線の矢視断面図である。
【図８】本発明の先行技術に係る切削ヘッド交換型のガンドリルの全体構成を示す部分省略正面図である。
【図９】同先行技術に係るガンドリルに用いるドリルヘッドを示し、（Ａ）は全体構成を示す部分省略正面図、（Ｂ）は先端から見た側面図、（Ｃ）は（Ａ）のＣ−Ｃ線の断面図、（Ｄ）は基端から見た側面図である。
【図１０】ガンドリルシステムに適用する３つの切刃を有する切削ヘッドを工具シャンクとは別部材とする場合の仮定構成を示し、（Ａ）は切削ヘッドの先端から見た側面図、（Ｂ）は基端側のねじ係合部の断面である。
【図１１】ガンドリルシステムの概略構成を示す断面図である。
【図１２】従来例のガンドリルを示し、（Ａ）は全体構成を示す部分省略正面図、（Ｂ）は先端から見た側面図、（Ｃ）は（Ａ）のＣ−Ｃ線の矢視断面図、（Ｄ）は（Ａ）のＤ−Ｄ線の矢視断面図である。
【符号の説明】
１工具シャンク
１ａ，１ｂ接続筒部（ねじ係合部）
１０ａドライバー部
１０ｂシャンク部
１１工具シャンク本体
１１ａドライバー部
１１ｂ基部シャンク
１２連結用シャンク軸
１２ａ接続軸部（ねじ係合部）
１２ｂ接続筒部（ねじ係合部）
２切削ヘッド
２ａ接続軸部（ねじ係合部）
２ｂ先端面
３，３ａ，３ｂ排出溝
４ａ雌ねじ
４ｂ雄ねじ
５，５ａ，５ｂクーラント供給通路
５０中心孔（クーラント供給通路）
６排出溝
６ａ先端開放部
７バイパス流路孔
７ａ排出口
８ａ，８ｂクーラント供給孔
８０ａ，８０ｂ吐出口
８１クーラント誘導凹所
９ａ中央部切刃
９ｂ中間部切刃
９ｃ周辺部切刃
１４埋込部材[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a deep hole cutting tool such as a drill applied to a gun drill system.
[0002]
[Prior art]
As a deep hole drilling system, a gun drill system, a BTA system, an ejector system and the like are known, but a gun drill system having a simple configuration is widely used for deep hole drilling of a relatively small diameter.
[0003]
As shown in FIG. 11, the gun drill system includes a gun drill 30 having a drill head 32 integrally fixed to the tip of a tool shank 31 having a hollow cylindrical shape and having a V-shaped cross-sectional groove formed in the outer surface along the longitudinal direction. The inside of the hollow portion of the tool shank 31 is used as a supply passage 33 for the coolant C, and the concave groove is used as a discharge groove 34 for the chips S. High-pressure coolant C is discharged from the tip side of the drill head 32 through the supply passage 33 during deep hole drilling. Then, the chip T generated in the cutting hole H of the workpiece W is discharged to the outside through the discharge groove 34 together with the coolant C. However, this gun drill system has an advantage that the chips T can be relatively easily discharged by allowing a large space for the discharge groove 34 even with a small diameter.
[0004]
As such a gun drill 30, the one shown in FIG. 12 is generally known. The tool shank 31 is formed in a cylindrical driver portion 31a, which is held by a chuck or the like and receives a rotational driving force, by die forming excluding the base end portion of a relatively thin pipe material, and has a V-shaped cross section along the longitudinal direction on the outer surface. A structure in which the base end of the cylindrical shaft portion 31b having the discharge groove 34a formed therein is fitted and fixed. Further, the drill head 32 has a discharge groove 34b similar to the cylindrical shaft portion 31b formed on the outer peripheral surface thereof by grinding of a steel material, and has a cutting edge formed at a tip portion facing one side surface of the discharge groove 34b. The tip 35 is brazed, and has a supply passage 33b communicating with the supply passage 33a of the tool shank 31 therein, and a discharge port 36 communicating with the supply passage 33b is opened at the front end surface. As the drill head 32, there is used a drill head which is entirely made of tool steel and has a cutting edge formed by grinding at the tip end, or a drill head which is formed by cutting a cutting edge made of a carbide tip. The tool shank 31 and the drill head 32 are integrated by fitting the angled base end 32a of the drill head 32 to the V-shaped tip of the cylindrical shaft portion 31b and brazing the fitting portion. Have been.
[0005]
However, in the conventional general-purpose gun drill 30 described above, when the cutting edge of the drill head 32 is worn out or broken, it is necessary to replace the entire cutting tool including the tool shank 31, which increases the cost and increases the setup cost. However, it takes a long time to replace the entire long cutting tool, resulting in a decrease in processing efficiency.Re-grinding work due to wear of the cutting edge is not easy, and the re-grinding cost is high. When the reaming is performed, a dedicated reamer tool having a reamer head fixed to the tip of the tool shank 31 is required, so that the cost is further increased.
[0006]
In view of the above, the present applicant has previously disclosed in Japanese Patent Application No. 2002-295789 a coolant supply passage having a hollow interior and a cutting head screwed to the tip of a tool shank having a discharge groove having a V-shaped cross section along the longitudinal direction on the outer peripheral surface. A deep hole cutting tool that is detachably attached by hole engagement has been proposed.
[0007]
In the deep hole cutting tool according to this proposal, for example, as shown in FIG. 8, the tool shank 21 has a cylindrical driver portion 21a, a shank portion 21b made of a pipe material inserted and fixed at the base end side, and a hollow at the tip end. A tubular mounting portion 21c is provided integrally, and a hollow interior communicating therewith is defined as a coolant supply passage 23a. Except for a base end of the shank portion 21b, the hollow mounting portion 21c is connected to the mounting portion 21c. A discharge groove 24a having a V-shaped cross section along the longitudinal direction is formed on the outer peripheral surface up to the end of the mounting portion 21c, and a female screw 27a is formed on the end side of the mounted portion 21c. As shown in FIG. 9, the cutting head 22 has a male screw 27 b screwed to the female screw 27 a of the mounted part 21 c on the base end side, and has a tool internally threadedly connected to the mounted part 21 c. It has a communication hole 23b communicating with the coolant supply passage 23a on the shank 21 side, and has a V-shaped concave groove 24b which is linearly connected to the discharge groove 24a on the tool shank 21 side in a state of being screwed to the outer peripheral surface. Is formed over the entire length including the male screw 27b, and has a cutting edge 25 provided at one end facing one side of the discharge groove 24b and a discharge port 26 which is an opening of the communication hole 23b.
[0008]
According to such a deep hole cutting tool, when the cutting blade 25 is worn or broken, the tool shank 21 can be continuously used only by replacing the cutting head 22 alone. In addition, a significant cost reduction can be achieved, and even when the setup is changed, only the cutting head 22 needs to be screwed in and replaced. Therefore, the work can be performed easily in a short time, the production efficiency is improved, and the cutting edge 25 is consumed. Re-grinding and replacement work can be easily performed by removing only the cutting head 22, and even when switching to another cutting work such as drilling and reaming, only the corresponding type of cutting head 22 needs to be prepared. Therefore, there is an advantage that equipment costs can be reduced and replacement work can be easily performed in a short time.
[0009]
On the other hand, a drill having a plurality of cutting edges is widely used as a tool with an oil hole used for drilling a hole having a relatively large diameter. However, since such a plurality of cutting edges are arranged so that the directions thereof are opposite to each other on both sides in the radial direction of the drill tip portion, when a cutting head having a plurality of cutting edges is used in a gun drill system, during machining. In order to efficiently discharge the chips, a discharge groove having a V-shaped cross section along the longitudinal direction is provided on both sides in the radial direction of the tool shank and the cutting head.
[0010]
[Problems to be solved by the invention]
However, in the configuration in which the tool shank and the cutting head are connected as separate members by screw engagement, as in the proposed deep hole cutting tool, when the tool shank and the cutting head are provided with discharge grooves on both sides in the radial direction, Due to the discharge grooves on both sides, the number of screw portions in the screw engagement portion is reduced, and the strength of the connection portion between the two becomes extremely weak.
[0011]
For example, FIG. 10 shows a hypothetical configuration in which a cutting head having three cutting edges applied to a gun drill system is formed as a separate member from a tool shank, (A) shows a head tip surface, and (B) shows a base end. It is a cross section of the screw engaging portion (male thread portion) on the side. As shown in the drawing, the cutting head 22P has large and small discharge grooves 24L and 24S having a V-shaped cross section on both sides in the radial direction, and one end of the large discharge groove 24L (rearward in the head rotation direction) is provided at the tip of the head. The center cutting edge 25a and the peripheral cutting edge 25c are provided facing the side surface of the small discharge groove 25S, and the intermediate cutting blade 25b is provided facing the same side surface (rear side in the head rotation direction) of the small discharge groove 25S. Coolant supply holes 23 are respectively provided in the substantially fan-shaped meat portions 28a, 28b on both sides separated by constriction by the two discharge grooves 25L, 25S, and each supply hole 23 opens as a discharge port 26 at the head end face. I have. Reference numeral 29 denotes a guide pad fixed to the outer peripheral surfaces of the meat portions 28a and 28b.
[0012]
Thus, in such a cutting head 22S, the area of the male screw 27b in the screw engaging portion on the proximal end side is cut off by the two discharge grooves 25L and 25S to form two arc portions as shown in FIG. In addition to the separation, even if the two arc portions are combined, it is only slightly more than の of the entire circumference, and the area of the corresponding female screw (not shown) of the screw engaging portion on the tool shank side is naturally the same. Become. Therefore, in the deep hole cutting tool in which the cutting head 22S is connected to the tool shank by screw engagement, the strength of the connection portion between the two becomes extremely weak, and the connection portion is broken, bent or twisted due to a cutting load. Deformation is likely to occur.
[0013]
The present invention has been made in view of the above circumstances, and has a configuration in which a tool shank and a cutting head are connected as separate members by screw engagement. It is an object of the present invention to provide a deep hole cutting tool capable of sufficiently securing the strength of a shank, a cutting head, and a connecting portion, and improving cutting efficiency by improving chip dischargeability.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, a deep hole cutting tool according to claim 1 of the present invention has a hollow inside as a coolant supply passage, and one discharge groove having a V-shaped cross section formed along a longitudinal direction of an outer peripheral surface. And a cutting head having a base end coaxially detachably connected to a distal end of the tool shank by screw engagement, wherein the cutting head is provided with a coolant for the tool shank in a connected state. A coolant supply hole communicating with the supply passage, a single discharge groove linearly connected to the discharge groove of the tool shank, and a discharge opening opening from the front end surface to the outer peripheral surface at a position substantially radially opposed to the discharge groove; An outlet, and a bypass passage hole extending from the discharge port to the discharge groove through the inside of the head, and a plurality of cutting blades respectively face the discharge groove and the discharge port at the tip of the cutting head. When distribution is formed by A, it is obtained by adopting the configuration in which two ejection port communicating with the coolant supply hole to the tip surface is open to a substantially opposite position in the radial direction.
[0015]
According to the deep hole cutting tool having the above-described configuration, since there is only one discharge groove having a V-shaped cross section formed along the longitudinal direction on the outer peripheral surface of the tool shank and the cutting head, the male screw of the screw engaging portion of both is provided. The region of the internal thread and the internal thread is cut off at one location in the circumferential direction by the discharge groove, and becomes a shape continuous in the circumferential direction over approximately 3/4. Therefore, the connecting portion formed by the thread engagement between the tool shank and the cutting head is provided with sufficient strength to withstand the cutting load, and is less likely to be deformed during processing such as breakage, bending, and twisting. However, the number of the discharge grooves is one, and the chips cut by the cutting blade on one side facing the discharge grooves are discharged through the discharge grooves as they are with the coolant discharged from the discharge port at the tip. However, the chips cut by the other cutting edge also flow into the discharge groove through the bypass flow passage together with the coolant discharged from the discharge port, and are discharged through the discharge groove. High cutting efficiency based on dischargeability can be obtained.
[0016]
In such a configuration, on the distal end surface of the cutting head, between the distal end opening portion of the discharge groove and the discharge port located on the front side in the head rotation direction, and on the discharge port and the front side in the head rotation direction. If the coolant guiding recesses are respectively formed between the discharge ports to be discharged, the coolant discharged at the head end can be evenly distributed to the discharge groove and the bypass flow passage hole, and the coolant is generated from the cutting blade facing each. Chips can be efficiently discharged together.
[0017]
In the configuration in which the cutting head has three cutting edges, that is, a central cutting edge, a peripheral cutting edge, and an intermediate cutting edge, the central cutting edge and the peripheral cutting edge are provided on the discharge groove side, and the bypass passage is provided. It is recommended that an intermediate cutting edge be arranged on the hole side, respectively. This is because chips flow directly into the discharge groove on the discharge groove side at the head end, while they merge into the discharge groove via the curved flow path on the bypass flow path hole side, so that the flow resistance between the two causes This is because there is a difference in the dischargeability, and it is preferable that the side where the amount of chips generated is larger is set to the discharge groove side having the higher dischargeability.
[0018]
The tool shank is provided with a tool shank body having a driver portion for receiving a rotational driving force, and a connection for coaxially detachably connecting one end side to the tip of the tool shank body by screw engagement. The connecting shank shaft may have a screw engaging portion with the cutting head at the other end of the connecting shank shaft. If the tool shank is divided in this way, the appropriate shank length corresponding to the drilling depth can be selected by exchanging the connecting shank shaft with a different length and removing it. In the event that the tool is worn out over time or sudden breakage or deformation occurs during processing, only the connecting shank shaft needs to be replaced, and the tool shank main body can be used continuously.
[0019]
Further, when the tool shank is divided as described above, the screw engagement portion between the tool shank main body and the connection shank shaft has the same size and shape as the screw engagement portion between the connection shank shaft and the cutting head. If set, it is possible to connect multiple connecting shank shafts as necessary, or to perform the required cutting by connecting the cutting head directly to the tool shank body without going through the connecting shank shaft It becomes possible.
[0020]
On the other hand, if the female screw and the male screw of the screw engaging portion are formed of square screws, the coupling strength is increased and a gap is hardly generated, so that leakage of the coolant from the screw engaging portion can be prevented.
[0021]
Furthermore, an embedding member that fills a threaded incision portion is arranged at the deep end of the female screw in the screw engagement portion, and if the embedding member is configured so that the end surface of the male screw is in close contact with the embedding member, the member can be manufactured at the time of manufacturing the member. Even if a slackened portion is formed for easy threading, the slackened portion is buried and no gap is formed. Therefore, it is possible to prevent a problem that chips are caught in the gap and cannot be discharged smoothly.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the deep hole cutting tool according to the present invention will be specifically described with reference to the drawings. 1 to 4 show a gun drill according to the first embodiment, and FIGS. 5 to 7 show a gun drill according to the second embodiment.
[0023]
As shown in FIGS. 1A to 1C, the gun drill according to the first embodiment has a cutting head that is coaxially detachably connected to a tool shank 1 by screwing a base end portion to a tip end thereof. 3 is comprised.
[0024]
The tool shank 1 includes a cylindrical driver portion 10a held by a chuck or the like and receiving a rotational driving force, and a substantially round shaft-shaped shank portion 10b whose base end side is fixedly fitted into the driver portion 10a. . The shank portion 10b is formed by welding and fixing a cylindrical member to the distal end of a pipe material by a V-shaped cut, and has a V-shaped discharge groove 3 along the longitudinal direction except for the base end side on the outer peripheral surface. Is formed to the front end, and a connection cylinder portion 1a having a bottom is provided on the front end side, and a female screw 4a formed of a square screw is engraved on the inner side of the connection cylinder portion 1a. The discharge groove 3 is formed in a fan shape having an opening of approximately 90 ° from the approximate center of the shank portion 10b, and is formed by die forming in the pipe material. In the connection cylindrical portion 1a, approximately 1/4 of the peripheral side wall is formed. Is cut out. Further, in the tool shank 1, a coolant supply passage 5 from the base end of the driver portion 10 a to the inner bottom of the connection tube portion 1 a is formed so as not to open to the discharge groove 3 due to the communication of the hollow portion of each component. ing.
[0025]
As shown in detail in FIGS. 2A to 2C, the cutting head 2 has a connection shaft portion 2a having an outer diameter whose base end can be closely fitted into the connection tube portion 1a of the tool shank 1. A male screw 4b composed of a square screw that is screwed into the female screw 4a of the connection cylinder portion 1a is engraved on the distal end side of the connection shaft portion 2a, and extends along the entire length including the connection shaft portion 2a on the outer peripheral surface. While one discharge groove 6 having a V-shaped cross section is formed, a discharge port 7a opened from the distal end surface 2b to the outer peripheral surface is provided at a position substantially radially opposed to the discharge groove 6 on the distal end side. A bypass passage hole 7 is formed from the discharge port 7a to the discharge groove 6 through the inside of the head. Reference numeral 7b denotes a junction opening in the discharge groove 5 of the bypass passage hole 7. Further, inside the cutting head 2, two coolant supply holes 8 a and 8 b extending from the end face of the connection shaft portion 2 a to the tip end face 2 b of the cutting head 2 avoid the discharge groove 6 and the bypass flow passage hole 7. The holes are formed so as to be substantially opposed to each other in the radial direction.
[0026]
At the tip of the cutting head 2, a central cutting edge 9 a and a peripheral cutting edge 9 b made of a carbide tip are screwed together with the discharge groove 6 facing the side surface on the rear side in the head rotation direction. The peripheral cutting edge 9c, which is also made of a carbide tip, is screwed so as to face the outlet 7a and to face the central cutting edge 9a and the peripheral cutting edge 9b in a reverse direction. The guide pad 13 is fixed to two places on the outer peripheral part outside the area 7a. Further, the front end face 2b has discharge ports 80a, 80b which are openings of both coolant supply holes 8a, 8b, and the discharge port 80a located at the front end opening part 6a of the discharge groove 6 and the front side in the head rotation direction. , And between the discharge port 7a and the discharge port 80b located on the front side in the head rotation direction, a coolant guiding recess 81 is formed. The coolant supply hole 8a corresponding to the discharge groove 6 and the discharge port 80a have a larger diameter than the coolant supply hole 8b corresponding to the discharge port 7a and the discharge port 80b.
[0027]
As shown in FIG. 1, the tool shank 1 and the cutting head 2 are connected to each other, that is, the connection shaft portion 2a of the cutting head 2 is fully fitted and screwed into the connection cylindrical portion 1a of the tool shank 1. In a state where the step 2c on the base side of the shaft portion 2a is in close contact with the end face of the connection tube portion 1a, the discharge grooves 3, 6 of the two 1 and 2 are linearly connected without displacement, and the coolant supply passage 5 of the former 1 is formed. The coolant supply holes 8a and 8b are set to communicate with each other. The length between the end face of the connection cylinder 1a of the tool shank 1 and the female screw 4a, and the distance between the step 2c on the base side of the connection shaft 2a of the cutting head 2 and the male screw 4b are the same and substantially the same. The connection shaft portion 2a is smoothly fitted into the connection tube portion 1a as the pilot portion having the inner and outer diameters so that the connection shaft portion 2a can be accurately screwed into a concentric state.
[0028]
The inner end of the female screw 4a in the connecting cylinder portion 1a of the tool shank 1 is screwed so that the end surface of the male screw 4b of the connecting shaft portion 2a of the cutting head 2 that is screwed into the female screw 4a is in close contact with the shaft so that no gap is formed. It is formed on a flat surface perpendicular to the core. Since it is actually difficult to perform the thread cutting process so that the inner end of the female screw 4a becomes a flat surface, specifically, as shown in FIG. An embedding member 14 made of a metal piece for burying the sunk portion is disposed and integrally fixed by brazing or the like.
[0029]
In the gun drill having the above configuration, since there is one discharge groove 3 and 6 having a V-shaped cross section formed along the longitudinal direction on the outer peripheral surfaces of the tool shank 1 and the cutting head 2, the female screw of the screw engagement portion of both is used. The region of 4a and the external thread 4b is cut off at one location in the circumferential direction by the discharge grooves 3 and 6, and becomes a shape continuous in the circumferential direction for approximately 3/4. Therefore, the connecting portion of the tool shank 1 and the cutting head 2 formed by the screw engagement has a sufficient strength to withstand the cutting load, and is less likely to be deformed during processing such as breakage, bending or twisting. Thus, although the cutting groove 2 of the cutting head 2 is only one, the chips cut by the central cutting edge 9a and the peripheral cutting edge 9b are not affected by the coolant discharged from the discharge port 80a at the tip. While being discharged through the discharge groove 6 and the discharge groove 3 of the tool shank 1, the chips cut by the intermediate cutting blade 9b also pass through the bypass passage 7 from the discharge port 7a together with the coolant discharged from the discharge port 80b. Then, it flows into the discharge groove 6 from the junction 7b, and is discharged through the discharge groove 6 and the discharge groove 3 of the tool shank 1. Therefore, according to this gun drill, high cutting efficiency based on good chip dischargeability can be obtained.
[0030]
In this embodiment, since the coolant guiding recess 81 extending from the discharge ports 80a, 80b to the discharge groove 6 and the discharge port 7a is formed in the front end surface 2b of the cutting head 2, the discharge is performed at the head front end. Coolant can be evenly distributed to the discharge groove 6 and the bypass flow passage hole 7, whereby the chips generated from the cutting blades 9a to 9c facing each other can be efficiently discharged together. Further, the central cutting edge 9a and the peripheral cutting edge 9c face the discharge groove 6 side, and the intermediate cutting edge 9b faces the discharge port 7a side, that is, the bypass passage hole 7 side. While a large amount of chips generated from the peripheral cutting edge 9c directly flows into the discharge groove 6, the intermediate cutting edge 9b forms a relatively small portion of the bypass flow passage hole 7 which is inferior in dischargeability due to the flow resistance of the curved flow passage. Since a small amount of chips flows in, the amount of chips flowing in is balanced in accordance with the difference in dischargeability between the discharge groove 6 and the bypass passage hole 7, so that a high chip dischargeability as a whole is secured.
[0031]
Further, in the present embodiment, since the female screw 4a and the male screw 4b in the screw engagement portion between the tool shank 1 and the cutting head 2 are formed by square screws, high coupling strength is obtained, and a gap is formed in the screw engagement portion. Is less likely to occur, so that leakage of the coolant from the screw engaging portion is prevented. In addition, since the embedding member 14 that fills the threaded portion for threading is disposed such that the distal end surface of the male screw 4b is in close contact with the inner edge of the female screw 4a, the threaded portion is formed to facilitate threading. In addition, the clearance is not formed due to the buried portion being buried, and leakage of the coolant is more reliably prevented. At the open end of the female screw 4a of the tool shank 1 and at the distal end of the male screw 5b of the cutting head 2, the incompletely threaded female and female screws 4a, 5b are completely threaded on both sides of the discharge grooves 3, 6. The end of the screw ends in the shape, and no gap is formed at the screw end facing the discharge grooves 3 and 6.
[0032]
On the other hand, in this gun drill, since the cutting head 2 is detachable from the tool shank 1, when the cutting blades 9a to 9c of the cutting head 2 are worn out or broken, only the cutting head 2 is replaced. Since the tool shank 1 can be continuously used as it is, and only the cutting head 2 needs to be screwed in and replaced at the time of setup change, the work can be performed easily in a short time, and the production efficiency is improved. 9C can be handled alone by removing only the cutting head 2 and replacing it due to wear of 9c. Therefore, even when switching to another cutting operation such as drilling and reaming, a corresponding type of cutting can be performed. Since only the head needs to be prepared, the equipment cost can be reduced and the replacement operation can be easily performed in a short time.
[0033]
In the gun drill according to the second embodiment, as shown in FIG. 5A, the tool shank 1 is divided into a tool shank main body 11 and a connecting shank shaft 12. However, since the cutting head 2 has the same configuration as that of the gun drill of the first embodiment, each component is denoted by the same reference numeral as in the first embodiment, and description thereof is omitted.
[0034]
As shown in detail in FIGS. 6 (A) to 6 (C), the tool shank main body 11 is provided with a small-diameter round shaft-like shape on the distal end side of a large-diameter driver portion 11a which is held by a chuck or the like and receives rotational driving force. A base shank 11b is integrally formed coaxially. A discharge groove 3a having a V-shaped cross section excluding the base end side is formed on the outer peripheral surface of the base shank 11b to the tip along the longitudinal direction. A connection tube 1b similar to the connection tube 1a in the tool shank 1 of the first embodiment is provided at the tip end of the connection shank 1b, and a female screw composed of a square screw is provided inside the connection tube 1b. 4a is engraved. As shown in FIGS. 6 (B) and 6 (C), the discharge groove 3a is formed in a fan shape having an opening of approximately 90 ° from the approximate center of the base shank 11b, and is substantially １／ of the circular cross section of the base shank 11b. And the peripheral side wall is cut out in the connection cylinder portion 1b. A center hole 50 extending from the base end to the intermediate position is formed in the driver portion 11a, and two coolant supply passages 5a, 5b, which extend from the inner bottom of the center hole 50 to the inner bottom of the connection tubular portion 1a of the base shank 11. 5a is formed so as to avoid the discharge groove 3a.
[0035]
The connecting shank shaft 12 has a round shaft shape having the same outer diameter as the base shank 11b of the tool shank main body 11, and as shown in detail in FIGS. It has a connection shaft portion 12a having an outer diameter that can be fitted tightly into the connection tube portion 1b of the main body 11, and is formed of a square screw that is screwed into the female screw 4a of the connection tube portion 1b at the tip end of the connection shaft portion 12a. A male screw 4b is engraved, and a connecting cylinder part 12b is formed on the other end side and has the same dimensions and shape as the connecting cylinder part 1b of the tool shank main body 11, and a female screw 4a formed of a square screw is engraved on the inner side. . On the outer peripheral surface of the connecting shank shaft 12, a discharge groove 3b having a V-shaped cross section along the longitudinal direction is formed over the entire length including the connecting shaft portion 12a and the connecting cylindrical portion 12b. Inside the shaft 12, two coolant supply passages 5b, 5b from the end face of the connection shaft portion 12a to the inner bottom of the connection cylinder portion 12b are formed so as to avoid the discharge groove 3b.
[0036]
As shown in FIGS. 5A and 5C, the tool shank main body 11 and the connection shank shaft 12 are connected to each other, that is, the connection shank shaft is connected to the connection cylinder portion 1b of the tool shank main body 11. 12 are fully fitted and screwed together, and in a state where the step 12c on the base side of the connection shaft portion 12a is in close contact with the end surface of the connection tube portion 1b, the two discharge grooves 3a and 3b are not shifted. The coolant supply passages 5a, 5a and the coolant supply passages 5b, 5b are set so as to be connected linearly. Further, the connecting shank shaft 12 and the connecting shaft portions 12a and 2a of the cutting head 2 have the same dimensions and shape, and as shown in FIGS. 5A and 5B, the connecting shaft portion 2a of the cutting head 2 is used for connecting. The discharge groove 6 is connected to the connection shank shaft 12a of the shank shaft 12a with the step 2c on the base side of the connection shaft portion 2a being in close contact with the end face of the connection tube portion 12b. And the coolant supply passages 8a and 8b are set so as to communicate with the coolant supply holes 5b and 5b of the connecting shank shaft 12.
[0037]
At the deep end of the internal thread 4a in the connection cylinder portions 1b, 12b of the tool shank main body 11 and the connecting shank shaft 12, like the connection cylinder portion 1a of the tool shank 1 according to the first embodiment, a thread cutting slimming portion. The embedding member 14 made of a metal piece for embedding is disposed and integrally fixed by brazing or the like. The tool shank body 11 and the connection shank shaft 12 between the connection shank shaft 12 and the base side steps 12c, 2c of the connection shaft portions 12a, 2a of the cutting head 2 and the male screw 5b, respectively, and the tool shank body 11 and the connection shank shaft 12 corresponding thereto. The connection shaft portions 12a and 2a are smoothly fitted into the connection cylinder portions 1b and 2b as pilot portions having the same length and substantially the same inner and outer diameters between the end surfaces of the connection cylinder portions 1b and 12b and the female screw 5a. It is configured so that it can be screwed exactly in a concentric state.
[0038]
According to the gun drill of the second embodiment, a high cutting efficiency can be obtained by good chip discharge performance at the cutting head 2, and a connecting portion formed by thread engagement between the cutting head 2 and the connecting shank shaft 12 can be provided. A sufficient strength can be ensured in the same manner as in the first embodiment, but in addition to this, the tool shank 1 is composed of the tool shank main body 11 and the connecting shank shaft 12 which is an independent member. If a plurality of different connecting shank shafts 2 are prepared as the tool shank shafts 12, the shank length can be changed by exchanging the shank shafts 2. There is an advantage that an appropriate shank length can be set. Therefore, the equipment cost is greatly reduced as compared with the case where a plurality of types of deep hole cutting tools having different shank lengths in several stages are prepared. In addition, most of the wear on the shank side over time, and sudden breakage and deformation on the shank side during use occur in the middle portion of the shank where torsional stress due to the cutting load tends to concentrate, but in the gun drill having the above configuration, Since the portion where the torsional stress is concentrated generally becomes the connecting shank shaft 2, by replacing only the damaged connecting shank shaft 12 with a new one, the tool shank body 11 which is hardly damaged but has a high manufacturing cost in terms of structure and size. Can be used continuously over a long period of time, which can greatly reduce maintenance costs.
[0039]
Further, in the gun drill of the present embodiment, one end of the connection shank shaft 12 forms a connection shaft portion 12a having a male screw 4b, and the other end forms a connection cylinder portion 12b having a female screw 4a. Since the connecting cylinder portions 1b and 12b of the connecting shank shaft 12 and the connecting shaft portions 12a and 2a of the connecting shank shaft 12 and the cutting head 2 are set to have the same dimensions and shape, a plurality of connecting shank shafts 12 are provided. Can be connected linearly, or the cutting head 2 can be directly connected to the tool shank main body 11 without the intermediation of the connecting shank shaft 12, and a plurality of connecting shank shafts 12 can be connected. Accordingly, it is possible to cope with extremely long holes, while conversely, it is possible to cope with relatively short holes by directly connecting the cutting head 2 to the tool shank body 11.
[0040]
On the other hand, when the cutting edges 9a to 9c of the cutting head 2 are worn out or broken, or when the setup is changed, only the cutting head 2 need be replaced similarly to the first embodiment, and the tool shank body 11 and The connection shank shaft 12 can be continuously used as it is, and the work can be performed easily and in a short time, thereby improving the production efficiency. Also in this embodiment, since the female screw 4a and the male screw 4b in each screw engaging portion of the connecting shank shaft 12, the tool shank main body 11, and the cutting head 2 are formed of square screws, high coupling strength is obtained. In addition, since a gap is hardly generated in the threaded portion, leakage of the coolant from the screw engaging portion is prevented. In addition, since the embedding member 14 that fills the threaded cutting portion is arranged so that the distal end surface of the male screw 4b is in close contact with the deep end of the female screw 4a, leakage of the coolant is more reliably prevented.
[0041]
In the first and second embodiments, the screw engaging portion of the tool shank 1 and the tool shank main body 11 is a female screw 4a. On the contrary, the screw engaging portion is a male screw 4b. The screw engaging portion on one end side of the connecting shank shaft 2 and the connecting shank shaft 12 may be a female screw 4a. As for the discharge holes 3, 3a, 3b, and 5, the opening angle of the V-shaped cross section is 90 °, but an appropriate opening angle in a range of approximately 90 ° to 130 ° can be set. The bottom may be rounded in order to improve the strength by increasing the thickness of the center side of each of the members 1, 11, 12, 2. On the other hand, as the cutting head, besides one having three cutting edges 9a to 9c as in the embodiment, one having two or four or more cutting edges may be used. Alternatively, it is also possible to use one in which the entire cutting head is made of tool steel and the cutting edge is formed directly at the tip.
[0042]
【The invention's effect】
According to the first aspect of the present invention, in a configuration in which the tool shank to which the gun drill system is applied and the cutting head are connected as separate members by screw engagement, the cutting head having a plurality of cutting blades is used. As a deep hole cutting tool, the tool shank and the outer peripheral surface of the cutting head are provided with one discharge groove linearly connected to the discharge groove of the tool shank, and the cutting head passes from the tip to the discharge groove through the inside of the head. By providing a bypass flow path hole to reach and distributing and forming a plurality of cutting blades facing the discharge groove and the discharge port on the bypass flow path hole side, the strength of the tool shank, the cutting head, and the connecting portion is sufficiently increased. That can improve the efficiency of cutting by improving the discharge of chips by the coolant.
[0043]
According to the invention of claim 2, in the above-described deep hole cutting tool, on the tip end surface of the cutting head, between the tip end opening portion of the discharge groove and the coolant discharge port located on the front side in the head rotation direction, and Since a coolant guide recess is formed between the discharge port and the discharge port located on the front side in the head rotation direction, the coolant discharged at the tip of the head is formed into a discharge groove and a bypass flow path hole. The chips generated from the cutting blades facing each can be efficiently discharged together.
[0044]
According to the invention of claim 3, in the above-described deep hole cutting tool having a cutting head having three cutting edges, a central cutting edge, a peripheral cutting edge, and an intermediate cutting edge, the cutting head is provided on the discharge groove side. Since the central cutting edge and the peripheral cutting edge and the intermediate cutting edge are arranged on the side of the bypass flow passage hole, chips flowing in corresponding to the difference in dischargeability between the discharge groove and the bypass flow passage hole. The balance of the amount is ensured, and high chip dischargeability is secured as a whole.
[0045]
According to the invention of claim 4, in the above-mentioned deep hole cutting tool, the tool shank is formed by the tool shank main body and the connecting shank shaft which is screw-engaged with the tip portion thereof and is coaxially detachably connected. Since the connecting shank shaft has a screw engaging portion for the cutting head at the other end side of the connecting shank shaft, by replacing a connecting shank shaft having a different length by attaching and detaching, the drilling depth can be reduced. Appropriate shank length can be selected correspondingly, equipment cost is greatly reduced compared to preparing tool shank with different shank length, and the aging of the connecting shank shaft is worn out, and unexpected during machining In case of severe breakage or deformation, the tool shank body can be used continuously by replacing only the connecting shank shaft, so the maintenance cost is greatly reduced compared to the case where the entire tool shank is replaced with a new one. It can be.
[0046]
According to the invention of claim 5, in the above-described deep hole cutting tool in which the tool shank is divided into the tool shank main body and the connection shank shaft, the screw engagement portion between the tool shank main body and the connection shank shaft is provided. Since the connecting shank shaft and the screw engaging part of the cutting head are set to the same dimensions and shape, it is possible to connect a plurality of connecting shank shafts linearly and cope with extremely long drilling, Conversely, the drill head can be directly connected to the tool shank main body without passing through the connecting shank shaft, so that relatively short drilling can be handled.
[0047]
According to the invention of claim 6, in the above deep hole cutting tool, since the female screw and the male screw of the screw engaging portion are formed of square screws, high coupling strength is obtained and a gap is formed in the screwing portion. Since it is unlikely to occur, there is an advantage that leakage of coolant from the screw engagement portion is prevented.
[0048]
According to the invention of claim 7, in the above deep hole cutting tool, an embedding member for embedding a threaded incision portion is arranged at a deep end portion of the female screw in the screw engagement portion, and the embedding member is provided with an embedding member. Since the end faces are configured to be close to each other, even if a slackened portion is formed to facilitate threading at the time of manufacturing the member, the slackened portion is filled and no gap is generated, so chips are caught in the gap. This makes it possible to prevent the occurrence of such a problem that discharge cannot be performed smoothly.
[Brief description of the drawings]
FIG. 1 is a partially omitted front view showing an entire configuration of a gun drill according to a first embodiment of the present invention.
2A and 2B show a cutting head used in the gun drill according to the first embodiment, wherein FIG. 2A is an overall front view, FIG. 2B is a side view seen from the tip, and FIG. 2C is a line CC in FIG. FIG.
FIG. 3 is a sectional view of the cutting head taken along line III-III of FIG. 2 (B).
FIG. 4 is a rear view of the same cutting head as viewed from a side opposite to FIG. 2A.
5A and 5B show a gun drill according to a second embodiment of the present invention, wherein FIG. 5A is a partially omitted front view showing the entire configuration, FIG. 5B is an enlarged view of a virtual line circle B in FIG. 4A is an enlarged view of the inside of a virtual line circle C of FIG.
6A and 6B show a tool shank main body used for the gun drill according to the second embodiment, wherein FIG. 6A is a partially omitted front view showing the entire configuration, FIG. 6B is a side view seen from the tip, and FIG. 5 is a sectional view taken along line CC of FIG.
7A and 7B show a connecting shank shaft used in the gun drill of the second embodiment, FIG. 7A is a partially omitted front view showing the entire configuration, FIG. 7B is a side view seen from the tip, and FIG. 2) is a sectional view taken along line CC of FIG.
FIG. 8 is a partially omitted front view showing the overall configuration of a cutting head exchange type gun drill according to the prior art of the present invention.
9A and 9B show a drill head used for the gun drill according to the prior art, in which FIG. 9A is a partially omitted front view showing the entire configuration, FIG. 9B is a side view seen from the tip, and FIG. FIG. 3D is a cross-sectional view taken along line C, and FIG.
FIG. 10 shows a hypothetical configuration in which a cutting head having three cutting edges applied to a gun drill system is formed as a separate member from a tool shank, (A) is a side view seen from the tip of the cutting head, and (B). Is a cross section of the screw engaging portion on the proximal end side.
FIG. 11 is a sectional view showing a schematic configuration of a gun drill system.
12A and 12B show a conventional gun drill, wherein FIG. 12A is a partially omitted front view showing the entire configuration, FIG. 12B is a side view seen from the tip, and FIG. 12C is a view taken along line CC of FIG. FIG. 3D is a cross-sectional view taken along line DD of FIG.
[Explanation of symbols]
1 Tool shank
1a, 1b Connection tube part (screw engagement part)
10a Driver section
10b Shank part
11 Tool shank body
11a Driver section
11b Base shank
12 Connection shank shaft
12a Connection shaft part (screw engagement part)
12b Connection tube part (screw engagement part)
2 Cutting head
2a Connection shaft part (screw engagement part)
2b Tip surface
3, 3a, 3b discharge groove
4a female screw
4b male screw
5,5a, 5b Coolant supply passage
50 center hole (coolant supply passage)
6 discharge grooves
6a Open end
7 Bypass channel hole
7a outlet
8a, 8b Coolant supply hole
80a, 80b outlet
81 Coolant guide recess
9a Central cutting edge
9b Intermediate cutting edge
9c Peripheral cutting blade
14 Embedded member

Claims

A tool shank having a hollow inside as a coolant supply passage and having a single V-shaped discharge groove formed along the longitudinal direction of the outer peripheral surface, and a proximal end portion of the tool shank at the distal end portion by screw engagement. With a cutting head that is coaxially detachably connected,
The cutting head has a coolant supply hole communicating with a coolant supply passage of the tool shank in a connected state, a single discharge groove linearly connected to a discharge groove of the tool shank, and a radial direction with respect to the discharge groove. A discharge port that opens from the distal end surface to the outer peripheral surface at a substantially opposing position, and a bypass flow path hole that extends from the discharge port through the inside of the head to the discharge groove,
At the tip of the cutting head, a plurality of cutting blades are distributed and formed facing the discharge groove and the discharge port, respectively, and two discharge ports communicating with the coolant supply hole at the distal end face are formed in a radial direction. A deep hole cutting tool that is open at almost the opposite position.

On the tip end surface of the cutting head, between the tip opening portion of the discharge groove and the discharge port located on the front side in the head rotation direction, and between the discharge port and the discharge port located on the front side in the head rotation direction. The deep hole cutting tool according to claim 1, wherein a coolant guide recess is formed between the recesses.

3. The deep hole cutting according to claim 1, wherein the cutting head has a central cutting edge and a peripheral cutting edge formed on the discharge groove side, and an intermediate cutting edge formed on the bypass flow passage hole side. 4. Utensils.

The tool shank includes a tool shank main body including a driver portion that receives a rotational driving force, and a connecting shank shaft that is coaxially detachably connected to one end of the tool shank main body by screwing one end to a tip end of the tool shank. The deep hole cutting tool according to any one of claims 1 to 3, further comprising a screw engaging portion for the cutting head at the other end of the connecting shank shaft.

5. The deep hole cutting tool according to claim 4, wherein a screw engaging portion between the tool shank main body and the connecting shank shaft has the same size and shape as a screw engaging portion between the connecting shank shaft and the cutting head.

The deep hole cutting tool according to any one of claims 1 to 5, wherein the female screw and the male screw of the screw engaging portion are formed by square screws.

7. An embedding member for burying a threaded incision portion at an inner end portion of the female screw in the screw engaging portion, wherein the embedding member is configured such that an end face of the male screw is in close contact with the embedding member. Deep hole cutting tool according to Crab.