JP3570688B2

JP3570688B2 - Tool abnormality detection device

Info

Publication number: JP3570688B2
Application number: JP07434594A
Authority: JP
Inventors: 克己長井; 史朗村井
Original assignee: 株式会社日平トヤマ
Priority date: 1994-03-18
Filing date: 1994-03-18
Publication date: 2004-09-29
Anticipated expiration: 2019-09-29
Also published as: JPH07256507A

Description

【０００１】
【産業上の利用分野】
この発明は、工作機械において、主軸に取り付けられたドリル等の工具の折損や摩耗等の異常を検出する工具異常検出装置に関する。
【０００２】
【従来の技術】
従来、ドリルの折損や摩耗等を検知する工具異常検出装置は、例えば本願出願人による特開平５−１４６９０９号公報に開示されているように、工具が取り付けられる主軸の軸方向負荷を軸受からピストンを介して油圧変化に変えて検知しているものがある。その検知方法は、この軸受を一対のピストンにより挟持し、このピストンを各々保持したシリンダ部と、この各シリンダ部に連続し上記軸受の軸方向前後端部の各々の側で独立して閉管路を形成した油圧管路とを設け、このシリンダ部及び各油圧管路に所定の圧力で油を密封し、上記油圧管路の油圧を圧力センサにより検知しているものである。そして、これにより、主軸に取り付けられた工具の折損や摩耗等により生じる加工抵抗の変化を、ピストンを介して軸方向に生じる油圧の変化に変換し、この油圧を圧力センサで検出して工具異常を検知することができるものである。
【０００３】
また、特公平５−２４３６６号公報に開示されているように、電気的に応力を検知する歪ゲージを主軸に取り付け、この歪ゲージの出力により、主軸に係る負荷を検知するものもある。
【０００４】
【発明が解決しようとする課題】
上記従来の技術の前者の場合、軸受自体が本体に保持されているので、軸受が摺動しにくく、そのわずかな移動が検知されにくく、検出信号のＳ／Ｎ比も良いものではなかった。
【０００５】
また、上記従来の技術の後者の場合、高速で回転する主軸から電気的に検知信号を取るために、ＦＭ送信機を主軸側に取り付け、ＦＭ受信機によりその検知信号を受けているものである。従って、電気系の構成が複雑であり、機械的電気的信頼性も低いものであった。
【０００６】
この発明は、上記従来の技術の問題点に鑑みて成されたもので、簡単な構成で検出精度が高い工具異常検出装置を提供することを目的とする。
【０００７】
【課題を解決するための手段】
この発明は、ドリル等の工具が取り付けられる主軸と、この主軸を収容した主軸ハウジングと、上記主軸の前後端部に位置し上記主軸ハウジングに対しこの主軸を回転自在かつスラスト方向に移動可能に支持した第一の軸受と、この第一の軸受間に位置し内輪が上記主軸に固定され内輪と外輪との間で上記主軸を回転自在かつスラスト方向に保持する第二の軸受と、上記主軸と主軸ハウジング間において上記主軸に対し回転自在かつ上記主軸ハウジングに対しスラスト方向に移動可能に嵌合され上記第二の軸受の外輪が固定されスラスト力を受ける検知部材と、この検知部材の上記工具とは反対側の端面と空間部を介して対向し上記主軸ハウジングに設けられたスラスト受け面と、上記空間部に加圧流体を供給する流体管路と、上記スラスト受け面での加圧流体の圧力を検知する圧力センサとを備えた工具異常検出装置である。さらに、上記スラスト受け面での加圧流体の圧力を検知する圧力センサと、上記主軸ハウジングの上記検知部材の側面と対面する位置に開口し上記加圧流体を供給する第一の流体管路と、上記主軸ハウジングの上記スラスト受け面に開口し常時圧力センサに流体圧を導く第二の流体管路とを備え、上記主軸ハウジングと上記検知部材との間の上記第一の流体管路の開口部から上記空間部へ上記加圧流体が通過可能な隙間が形成された工具異常検出装置である。
【０００８】
また、上記スラスト受け面と対面する上記検知部材の端面には、上記隙間から上記第二の流体管路に向かって上記加圧流体が通過可能な溝が形成されている。または、上記検知部材と対面する上記スラスト受け面には、上記隙間から上記第二の流体管路に向かって上記加圧流体が通過可能な溝が形成されているものである。また、上記検知部材には、上記主軸ハウジングに対し回転を阻止する回り止めが設けられているものである。
【０００９】
またこの発明は、ドリル等の工具が取り付けられる主軸と、この主軸を収容した主軸ハウジングと、上記主軸の前後端部に位置し上記主軸ハウジングに対しこの主軸を回転自在かつスラスト方向に移動可能に支持した第一の軸受と、この第一の軸受間に位置し内輪が上記主軸に固定され内輪と外輪との間で上記主軸を回転自在かつスラスト方向に保持する第二の軸受と、上記主軸と主軸ハウジング間において上記主軸に対し回転自在かつ上記主軸ハウジングに対しスラスト方向に移動可能に嵌合され上記第二の軸受の外輪が固定されスラスト力を受ける検知部材と、この検知部材の上記工具とは反対側の端面と空間部を介して対向し上記主軸ハウジングに設けられたスラスト受け面と、このスラスト受け面に開口し上記空間部に加圧流体を供給する流体管路と、上記スラスト受け面での加圧流体の圧力を検知する圧力センサを備えた工具異常検出装置である。上記主軸ハウジングの上記スラスト受け面に開口し上記スラスト受け面に、上記圧力センサに流体圧を導く流体管路を備えている。また。上記スラスト受け面に、上記加圧流体を供給する流体管路の開口部から上記圧力センサに流体圧を導く流体管路の開口部に連通する溝が形成されている。上記検知部材には、上記主軸ハウジングに対し回転を阻止する回り止めが設けられている工具異常検出装置である。
【００１０】
さらにこの発明は、ドリル等の工具が取り付けられる主軸と、この主軸を収容した主軸ハウジングと、上記主軸の前後端部に位置し上記主軸ハウジングに対し上記主軸を回転自在かつスラスト方向に移動可能に保持した第一の軸受と、この第一の軸受間に位置し一方の回転輪が上記主軸ハウジングに固定され上記主軸に遊嵌された第二の軸受と、上記主軸と一体的に設けられスラスト方向に上記第二の軸受の他方の回転輪と対向するフランジ部と、上記主軸ハウジングに形成され上記主軸側に開口して加圧流体を供給する流体管路と、上記主軸のフランジ部とスラスト方向に空間部を介して対面し上記第二の軸受の他方の回転輪に固定された検知部材と、この検知部材に形成され一方の開口部が上記主軸ハウジングの流体管路の開口部と連通し他方の開口部が上記主軸のフランジ部と対面する流体管路と、上記主軸ハウジングに形成された流体管路内の加圧流体の圧力を検知する圧力センサとを備えた工具異常検出装置である。
【００１１】
さらにこの発明は、ドリル等の工具が取り付けられる主軸と、この主軸を収容した主軸ハウジングと、上記主軸の前後端部に位置し上記主軸ハウジングに対し上記主軸を回転自在かつスラスト方向に保持する第一の軸受と、この第一の軸受間に位置し上記主軸を回転自在かつスラスト方向に保持する一対の第二の軸受と、この一対の第二の軸受のそれぞれの内輪を上記主軸に固定するとともに、前方側の上記第二の軸受の外輪を上記主軸ハウジングに対し回り止め状態でかつスラスト方向にわずかに移動可能に設け、後方側の上記第二の軸受の外輪を上記主軸ハウジング側に支持し、上記主軸側に開口して加圧流体を供給する流体管路を上記主軸ハウジングに形成し、上記一対の第二の軸受の外輪間に設けられ上記前方側の第二の軸受の端面と空間部を介して対向し上記後方側の第二の軸受の外輪に支持された検知部材と、この検知部材に形成され一方の開口部が上記主軸ハウジングの流体管路の開口部と連通し他方の開口部が上記前方側の第二の軸受の外輪の端面と対面する流体管路と、上記主軸ハウジングに形成された流体管路内の加圧流体の圧力を検知する圧力センサとを備えた工具異常検出装置である。
【００１２】
【作用】
この発明の工具異常検出装置は、主軸を主軸ハウジングに対し、前後の第一の軸受と中間の第二の軸受による３点支持することで剛性を向上させ、しかも、検知部材を主軸とともにスラスト方向に移動しやすく支持したことにより、主軸に取り付けられた工具の折損や摩耗等の場合に生じる加工抵抗を検知するに際して、主軸にかかるスラスト力を、そのまま検知部材の動きに変えることができ、この検知部材とそれに対面する部材との間に加圧流体を供給し、この加圧流体の圧力を圧力センサに導いて検出し、その圧力の変化により、加工抵抗や、工具の折損、摩耗、欠け等の異常を検知するものである。
【００１３】
【実施例】
以下この発明の実施例について図面に基づいて説明する。図１〜図５は、この発明の第一実施例を示すもので、この実施例の工具異常検出装置は、ドリル等の工具１０が取り付けられた主軸１２と、この主軸１２を収容した主軸ハウジング１６とを有した各種工作機械に利用されるものである。主軸１２の工具１０側である前端部とその反対側である後端部において、主軸ハウジング１６と主軸１２との間には、ラジアル方向の位置を規制するとともに、主軸１２とともにスラスト方向にわずかに移動可能な円筒コロ軸受等のラジアル軸受である第一の軸受としての一対の軸受１４，１５が設けられている。軸受１４は、主軸ハウジング１６の工具１０側で、その外輪１４ａの一端が主軸ハウジング１６の段部１６ａに当接し、外輪１４ａの他端が取付部材１８により保持されて主軸ハウジング１６に対して固定されている。そして、軸受１４の内輪１４ｂが主軸１２に固定されて、スラスト方向に主軸１２とともにわずかに移動可能に設けられている。また、軸受１５も軸受１４と同様の構成で、外輪１５ａが主軸ハウジング１６に固定され、内輪１５ｂが主軸１２に固定され、主軸１２がスラスト方向にわずかに移動可能に設けられている。
【００１４】
主軸１２の軸受１４，１５間には、スラスト方向の荷重を受けることができるアンギュラ玉軸受け等の第二の軸受としての軸受２０が設けられている。軸受２０は、スラスト方向前後の力を受けることができる様に一対設けられ、その内輪２０ｂが主軸１２に固定されている。そして、軸受１４の内輪１４ｂと軸受２０の内輪２０ｂとの間に金属製のスペーサ１７が嵌め込まれ、主軸１２の工具１０側のストッパ面１２ａに、軸受１４の内輪１４ｂが当接し、軸受２０の内輪２０ｂがスペーサ１７を介して主軸１２に螺合したナット１９により締めつけられて固定されている。また、外輪２０ａは、有底円筒状の検知部材２２の内側面の段部２２ａに当接して固定されている。検知部材２２は、円筒端面の透孔２４に主軸１２が、回転可能に同軸的に挿通され、スラスト方向に主軸１２とともに移動可能に設けられている。
【００１５】
検知部材２２には、外側面に主軸１２の軸線方向に形成された長溝２６が設けられ、長溝２６に、主軸ハウジング１６に螺合された回り止めネジ２８の先端部が位置し、検知部材２２がスラスト方向に移動可能であるとともに回転不能にガイドしている。また、検知部材２２の先端部は、主軸ハウジング１６の内壁面に固定された軸止め輪２３に所定の位置で当接可能に設けられている。検知部材２２と、主軸ハウジング１２の内周面との間隔δｒは、全周に渡って、加圧流体が通過可能な、ほぼ１０〜２０μｍ程度の隙間に形成されている。検知部材２２の端面の外側表面には、図３に示すように、放射状に３方向に形成された、加圧流体が通過可能な溝３０が設けられている。この溝３０の深さδｈは、約３０〜４０μｍ程度であり、外側面から中心部の透孔２４付近まで形成されている。なお、この溝３０は、図１の２点鎖線で示すように、主軸ハウジング１６のスラスト受け面３２側に、溝３０に代えて同様に溝３０’を形成しても良いものである。また、検知部材２２の端面と対面して、この検知部材２２をスラスト方向に支持するスラスト受け面３２が主軸ハウジング１２に形成されている。そして、検知部材２２の端面の外側表面とスラスト受け面３２との間隔δｄは、ほぼ５０μｍ程度からそれ以下に、主軸１２のスラスト方向移動により変化する。
【００１６】
主軸ハウジング１６には、検知部材２２の側面に開口して加圧エア供給源に接続され加圧エアを供給する流体管路３４が形成され、この流体管路３４の開口部３４ａと対面した検知部材２２の側面には凹部３６が形成されている。主軸ハウジング１６のスラスト受け面３２には、その主軸１２の近傍に、主軸ハウジング１６に内に形成された流体管路３８の一端の開口部３８ｄが開口し、流体管路３８の他端は、流体の圧力を電気的に検知する半導体ダイヤフラム圧力センサ等の圧力センサ４０に接続されている。
【００１７】
この実施例の工具異常検出装置の動作は、工具１０を主軸１２に取り付け、ワーク５０をセットした後、図示しない主軸モータを回転させ、主軸１２を所定回転数で回転させる。そして、図示しない摺動機構及び送りモータにより主軸ハウジング１６をワークに向かって移動させる。この時、加圧エア源より、加圧エアを流体管路３４に供給する。これにより、主軸ハウジング１６内の検知部材２２と、主軸ハウジング１６のスラスト受け面３２との間に加圧エアが送り込まれ、静圧空気軸受と同様に機能する。また、その加圧エアの圧力により、検知部材２２とともに主軸１２、軸受２０、及び軸受１４の内輪１４ｂが工具１０側に微小量移動し、図示しないストッパに当接して停止する。これにより、検知部材２２の端面の外側表面とスラスト受け面３２との間に、ほぼ５０μｍ程度の間隙の空間部が形成される。これにより、流体管路３８を経て圧力センサ４０により検出される圧力は、大気圧に開放されている主軸１２の周面部と同様に、ほぼゲージ圧よりわずかに高い圧力を示している。
【００１８】
そして、工具１０の先端がワーク５０に当接し加工が開始されると、その加工抵抗により、主軸１２にはスラスト方向に力が作用し、軸受２０には、このスラスト力により、検知部材２２とともにわずかに、工具１０とは反対方向に移動する。この移動距離は、数十μｍ程度である。この加圧エアの流体管路３４の開口部３４ａから流体管路３８の開口部３８ｄまでの圧力低下は、図４に示すような傾向を示す。
【００１９】
即ち、図２、図４に示すように、流体管路３４の開口部３４ａのａ地点から検知部材２２の端面の角部ｂ地点までの圧力損失に対して、端面の角部ｂ地点から溝３０の中心部側端部ｃ地点までの圧力損失は小さく、溝３０の中心側端部ｃ地点から大気圧に開放されたｄ地点までの圧力損失は、きわめて急激に生じるものである。これは、検知部材２２の外周面と主軸ハウジング１６の内周面との隙間が、１０〜２０μｍときわめて小さいのに対して、検知部材端面とスラスト受け面３２との間は、スラスト力がかかった状態でも、検知部材２２の端面の溝３０により、適切な流体通路が形成され、圧力損失が小さいからである。そして、流体管路３８の開口部３８ｄは、このｄ地点よりわずかに溝３０の中心部側端部ｃ地点寄りに位置し、このｃ−ｄ地点間の圧力の急激な変化を、流体管路３８により圧力センサ４０に伝達可能に設けられている。なお、この溝３０がないと、この加圧エアの流路ａ−ｂ−ｃ−ｄにおける圧力損失は、図４の破線に示すように、一様に低下する傾向となる。
【００２０】
そして、図示しない制御装置により工具１０の送り量が制御されており、工具１０の先端がワーク５０に当接する位置及びタイミングが分かるので、工具１０を回転させながらワーク５０の表面から数ｍｍ進んだところで、圧力センサ４０の出力を図示しない制御装置が検知する。圧力センサ４０の出力は、図５に示すように、時間ｔ１でワーク５０に工具１０が当接し、スラスト力が主軸１２にかかると、圧力センサ４０の出力も急激に立ち上がり、スラスト力が横ばいになると圧力センサ出力もほぼ一定となる。ここで、図５に示すように、主軸１０にかかるスラスト力を歪ゲージ等の測定装置で測定すると、加工抵抗の変動等によって、高い周波数で大きな変動波形が得られる。従って、このスラスト力の測定値を基にスラスト力の判別を行うと、誤差が大きくなってしまうものである。しかし、加圧エアを介して、スラスト力を測るようにしたこの実施例では、加圧エアがダンパとして作用し、図５の圧力センサ出力に示すように、滑らかな曲線として検出され、正確な判別が可能となる。
【００２１】
この圧力センサ４０の出力を基に、工具１０の折損検知を行うには、工具１０が折損している場合、正常な工具１０であれば、ワーク５０内へ数ｍｍ進んだ状態でも、折損した工具１０はワークに達していないので、主軸１２にはスラスト力が作用せず、圧力センサ４０の出力は立ち上がらない。従って、工具１０がワーク５０に接触する前の圧力センサ４０の出力よりわずかに高い値を閾値Ｖ１としておけば、工具１０がワーク５０内へ数ｍｍ進んだ時点ｔ２で確実に折損検知を行うことができる。
【００２２】
また、工具１０が摩耗している場合、加工抵抗がおおきくなり主軸１２にかかるスラスト力も大きくなる。従って、圧力センサ４０の出力が一定となる定常加工時の圧力センサ出力が、摩耗限界となった工具１０により得られる圧力センサ４０の出力の定常出力値Ｖ２以上となった時に、摩耗と判断するように設定することができる。
【００２３】
さらに、例えば、工具１０の先端部がわずかに欠けた場合、工具１０は、正常な工具と同様にワーク１０に当接するので、上述の折損検知では、発見できない。しかし、この場合、工具１０の刃が欠けているので、加工抵抗はきわめて大きくなりスラスト力も異常に大きなものとなる。従って、通常の加工では生じ得ない大きなスラスト力に対して、一定の閾値Ｖ３を設定しておくことにより、工具の欠け等の異常も検知することができる。
【００２４】
この実施例の工具異常検出装置は、加圧エアを検知部材２２と主軸ハウジング１６の間に印加し、主軸ハウジング１６内のスラスト受け面３２と検知部材２２との間の加圧エア圧力により、スラスト力に対応した出力を得て、工具異常を判断しているものであり、圧力センサ４０の出力が安定しており、ノイズが少なく、きわめてＳ／Ｎ比の良い検知信号を得ることができる。従って、精度良く、折損検知や、摩耗検知、さらには工具の欠け等の異常をも検知することができる。また、回り止めネジ２８により検知部材２２の主軸１２回りの回転が阻止されているので、検知部材２２がスラスト受け面３２に当接した際にも、主軸１２の回転により当接面が焼き付くようなこともない。
【００２５】
次に、この発明の第二実施例について図６、図７に基づいて説明する。ここで、上述の実施例と同様の部材については同一符号を付して説明を省略する。この実施例の工具異常検出装置は、主軸ハウジング１６のスラスト受け面３２に、加圧エアの供給源に接続された流体管路３４の開口部３４ａと、圧力センサ４０に接続された流体管路３８の開口部３８ｄが、溝４２によって連接されて設けられたものである。溝４２の深さは、約３０〜４０μｍ程度であり、検知部材２２の平な端面がスラスト受け面３２に当接した状態で、加圧エアが圧力損失を伴って、流体管路３８の開口部３８ｄに伝達される程度の長さである。
【００２６】
この実施例の工具異常検出装置の動作は、上記第一実施例と同様であり、加圧エア供給当初は、検知部材２２が主軸ハウジング１６のスラスト受け面３２から離間しており、圧力センサ４０の出力は、ゲージ圧よりわずかに高い程度である。そして工具１０がワーク５０に当接して、スラスト力がかかると、検知部材２２が主軸ハウジング１６のスラスト受け面３２側に移動し、流体管路３４，３８の開口部３４ａ，３８ｄを塞ぐように位置する。これにより、加圧エアは、溝４２を通って、流体管路３４の開口部３４ａから流体管路３８の開口部３８ｄに伝わる。この時、スラスト力により検知部材２２のスラスト受け面３２への近接状態が異なり、上記実施例と同様に、圧力センサ４０の出力が異なる。即ち、スラスト力が小さいと、検知部材２２とスラスト受け面３２との間が比較的広く、圧力センサ４０に検知される圧力は比較的小さい。また、加工抵抗が大きくスラスト力が大きくなると、この間が狭くなって、大気側へ逃げる圧力が小さくなり、圧力センサ４０に伝わる圧力が大きくなるものである。これにより、工具１０の折損、摩耗、欠け等を正確に検知できるものである。
【００２７】
この実施例の工具異常検出装置によっても上記第一実施例と同様の効果が得られるものであり、さらに、検知部材２２等の構造を簡単なものにすることができる。
【００２８】
次に、この発明の第三実施例について図８に基づいて説明する。ここで、上述の実施例と同様の部材については同一符号を付して説明を省略する。この実施例の工具異常検出装置は、主軸ハウジング１６に取付部材４５を介して一方の回転輪が固定されスラスト方向に主軸１２を保持するスラスト玉軸受け等の軸受４４が設けられ、主軸１２には、スラスト方向に軸受４４と対向するフランジ部４６が一体的に設けられている。さらに、主軸１２側に開口して加圧エアを供給するとともに、圧力センサ４０にも接続された流体管路４８が、主軸ハウジング１６内に形成されている。この加圧エアは、圧力センサ４０側の流体管路との合流点の手前の絞り４１を経て流体管路４８に接続され、軸受４４の他方の回転輪４４ｂには、主軸１２側のフランジ部４６とスラスト方向に対面したリング状の検知部材５２が固定されている。この検知部材５２には、流体管路５４が形成され、一方の開口部５４ａが主軸ハウジング１６の流体管路４８の開口部４８ａと対面し、他方の開口部５４ｂが、主軸１２側のフランジ部４６の端面と対面している。
【００２９】
この実施例の工具異常検出装置の動作は、上記第一実施例と同様であり、加圧エア供給当初は、検知部材５２の流体管路５４から加圧エアが主軸１２に設けられたフランジ部４６に噴射され、フランジ部４６は、主軸１２とともに、検知部材５２から数十μｍ程度離間しており、圧力センサ４０の出力は、ゲージ圧よりわずかに高い程度である。そして、工具１０がワーク５０に当接して、スラスト力がかかると、フランジ部４６が検知部材５２の流体管路５４の開口部５４ｂを塞ぐ。この時、フランジ部４６は主軸１２と一体に高速で回転しているが、検知部材５２は軸受４４に設けられているので、回転しながらスラスト方向に主軸１２を支持する。
【００３０】
そして、フランジ部４６が検知部材５２の流体管路５４の開口部５４ｂを塞ぐことにより、圧力センサ４０には、加圧エア供給源からの圧力が直接かかり、その圧力が検知される。従って、例えば正常な工具１０がワーク５０に当接した後、数ｍｍ進んだ位置で圧力を検知すると、正常な場合は、圧力センサ４０の検知圧力が高くなる。一方、折損工具の場合は、その位置でもワークに当接していないので、スラスト力が作用せず、フランジ部４６により流体管路５４の開口部５４ｂが塞がれない。従って、圧力センサ４０にかかる圧力は上昇せず、工具の折損が検知される。
【００３１】
この実施例の工具異常検出装置によっても上記第一実施例と同様に、比較的ノイズの少ない検知が可能となるものである。
【００３２】
次に、この発明の第四実施例について図９、図１０に基づいて説明する。ここで、上述の実施例と同様の部材については同一符号を付して説明を省略する。この実施例の工具異常検出装置は、主軸１２を回転自在かつスラスト方向に保持するアンギュラ玉軸受け等の一対の第二の軸受６０，６１が設けられ、この軸受６０，６１は、それぞれ内輪６０ｂ，６１ｂがスペーサ１７とナット６３の締め付けにより主軸１２に固定されている。軸受６１の外輪６１ａは主軸ハウジング１６の段部１６ｂに当接し、また、この外輪６１ａの前端面には、リング状の検知部材６２が当接されている。軸受６０の外輪６０ａと検知部材６２との間には、圧縮スプリング６５が設けられ、その作用で、上記検知部材６２と外輪６１ａが常時主軸ハウジング１６の段部１６ｂに向かって押圧されている。そして、外輪６０ａと検知部材６２との間には、隙間δが形成されている。外輪６０ａは、回り止めネジ２８によって回り止めされ、かつ主軸１２とともにスラスト方向にわずかに移動自在に支持されている。検知部材６２には、流体管路６４が形成され、一方の開口部６４ａが主軸ハウジング１６の流体管路６６の開口部６６ａと対面し、他方の開口部６４ｂが、主軸１２とともにスラスト方向に移動可能な軸受６０の外輪６０ａの端面に向かって開口している。流体管路６６は、加圧エア供給源に接続されているとともに、圧力センサ４０にも接続されている。
【００３３】
この実施例の工具異常検出装置の動作は、上記第三実施例と同様であり、加圧エア供給当初は、検知部材６２の流体管路６４から加圧エアが主軸１２に設けられた軸受６０の外輪６０ａに噴射され、主軸１２は軸受６０とともに、検知部材６２から数十μｍ程度離間しており、圧力センサ４０の出力は、ゲージ圧よりわずかに高い程度である。そして、工具１０がワーク５０に当接して、スラスト力がかかると、主軸１２とともに軸受６０が検知部材６２の端面に当接し、検知部材６２の流体管路６４の開口部６４ｂを塞ぐ。これにより、流体管路６４の開口部６４ｂが塞がれ、圧力センサ４０には、加圧エア供給源からの圧力が直接かかり、その圧力が検知される。従って、例えば正常な工具１０がワーク５０に当接した後、数ｍｍ進んだ位置で圧力を検知すると、圧力センサ４０の検知圧力が高くなる。一方、折損工具の場合は、その位置でもワークに当接していないので、スラスト力が作用せず、軸受６０により検知部材６２の流体管路６４の開口部６４ｂが塞がれない。従って、圧力センサ４０にかかる圧力は上昇せず、所定の出力が得られないので工具の折損が検知される。
【００３４】
この実施例の工具異常検出装置によっても上記第三実施例と同様の効果が得られるものであり、さらに、検知部材６２や軸受６０，６１等の取付構造を簡単なものにすることができる。
【００３５】
なお、この発明は、上記実施例の他、各実施例において加圧流体として、オイルを用いても良く、オイルを用いることにより、軸受の潤滑を同時に行うことができるという効果がある。
【００３６】
【発明の効果】
この発明の工具異常検出装置は、主軸にかかるスラスト力を、加圧流体を介して圧力センサにより検知しているので、加工抵抗の変動等によるスラスト力の変動の影響を受けにくく、Ｓ／Ｎ比の良い検知が可能である。従って、高精度に工具の異常を検知することができ、検知可能な異常の種類も多いものである。
【図面の簡単な説明】
【図１】この発明の工具異常検出装置の第一実施例の概略縦断面図である。
【図２】この発明の第一実施例の軸受と検知部材の部分拡大縦断面図である。
【図３】この発明の第一実施例の検知部材の正面図である。
【図４】この発明の第一実施例の加圧流体経路の圧力損失を示すグラフである。
【図５】この発明の第一実施例の圧力センサの出力と、主軸にかかるスラスト力を示すグラフである。
【図６】この発明の第二実施例の軸受と検知部材の概略縦断面図である。
【図７】この発明の第二実施例の主軸ハウジングのスラスト受け面の正面図である。
【図８】この発明の工具異常検出装置の第三実施例の概略縦断面図である。
【図９】この発明の工具異常検出装置の第四実施例の概略縦断面図である。
【図１０】この発明の工具異常検出装置の第四実施例の部分拡大縦断面図である。
【符号の説明】
１０工具
１２主軸
１４，１５，２０，４４，６０，６１軸受
１６主軸ハウジング
２２，５２，６２検知部材
３２スラスト受け面
３４，３８，４８，５４，６４，６６流体管路
４０圧力センサ[0001]
[Industrial applications]
The present invention relates to a tool abnormality detection device for detecting an abnormality such as breakage or wear of a tool such as a drill attached to a spindle in a machine tool.
[0002]
[Prior art]
Conventionally, a tool abnormality detecting device for detecting breakage or wear of a drill has been disclosed in, for example, Japanese Patent Application Laid-Open No. 5-146909 by the applicant of the present invention. There is a device that detects a change in the hydraulic pressure via a. The detection method is such that the bearing is sandwiched between a pair of pistons, and a cylinder portion holding each of the pistons, and a closed pipe line which is continuous with each of the cylinder portions and independently at each of the axial front and rear ends of the bearing. Is provided with a hydraulic pressure line, oil is sealed in the cylinder portion and each hydraulic pressure line with a predetermined pressure, and the oil pressure in the hydraulic pressure line is detected by a pressure sensor. This converts the change in machining resistance caused by breakage or wear of the tool attached to the spindle into a change in oil pressure generated in the axial direction via the piston, and detects this oil pressure with a pressure sensor to detect a tool abnormality. Can be detected.
[0003]
Further, as disclosed in Japanese Patent Publication No. H5-24366, a strain gauge that electrically detects a stress is attached to a main shaft, and an output of the strain gauge detects a load on the main shaft.
[0004]
[Problems to be solved by the invention]
In the former case of the above prior art, since the bearing itself is held by the main body, the bearing is not easily slid, its slight movement is hard to be detected, and the S / N ratio of the detection signal is not good.
[0005]
In the latter case of the above-mentioned conventional technology, an FM transmitter is mounted on the main shaft side in order to electrically take a detection signal from a main shaft rotating at a high speed, and the detection signal is received by an FM receiver. . Therefore, the configuration of the electric system is complicated and the mechanical and electrical reliability is low.
[0006]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the related art, and has as its object to provide a tool abnormality detection device having a simple configuration and high detection accuracy.
[0007]
[Means for Solving the Problems]
The present invention provides a spindle to which a tool such as a drill is attached, a spindle housing accommodating the spindle, and supports the spindle so as to be rotatable and movable in the thrust direction with respect to the spindle housing at front and rear ends of the spindle. A first bearing, a second bearing positioned between the first bearing, the inner ring is fixed to the main shaft, and the second bearing rotatably holds the main shaft in the thrust direction between the inner ring and the outer ring; and A detecting member which is rotatably fitted to the main shaft between the main shaft housings and is movably fitted to the main shaft housing in the thrust direction, and an outer ring of the second bearing is fixed and receives a thrust force; A thrust receiving surface provided in the main spindle housing and opposed to the opposite end surface via a space, a fluid conduit for supplying pressurized fluid to the space, Only a tool abnormality detecting device provided with a pressure sensor for detecting the pressure of the pressurized fluid in terms. Further, a pressure sensor for detecting the pressure of the pressurized fluid at the thrust receiving surface, and a first fluid conduit that opens at a position facing the side surface of the detection member of the spindle housing and supplies the pressurized fluid, A second fluid conduit opening in the thrust receiving surface of the spindle housing and constantly guiding fluid pressure to a pressure sensor, wherein an opening of the first fluid conduit between the spindle housing and the detection member is provided. A tool abnormality detection device in which a gap through which the pressurized fluid can pass from a portion to the space portion is formed.
[0008]
A groove through which the pressurized fluid can pass from the gap toward the second fluid conduit is formed on an end surface of the detection member facing the thrust receiving surface. Alternatively, the thrust receiving surface facing the detection member is formed with a groove through which the pressurized fluid can pass from the gap toward the second fluid conduit. Further, the detection member is provided with a detent for preventing rotation with respect to the spindle housing.
[0009]
Further, the present invention provides a spindle to which a tool such as a drill is attached, a spindle housing accommodating the spindle, and a spindle rotatably and movable in a thrust direction with respect to the spindle housing located at front and rear ends of the spindle. A first bearing supported, a second bearing positioned between the first bearing, an inner ring fixed to the main shaft, the second bearing rotatably holding the main shaft in the thrust direction between the inner ring and the outer ring, and the main shaft A detecting member which is rotatable with respect to the main shaft and movable in the thrust direction with respect to the main shaft housing between the main shaft housing and the main shaft housing, the outer ring of the second bearing is fixed and receives a thrust force, and the tool of the detecting member A thrust receiving surface provided in the main spindle housing and opposed to an end surface opposite to the end surface via a space portion, and a pressurized fluid is supplied to the space portion opened in the thrust receiving surface. A fluid line to a tool abnormality detecting device provided with a pressure sensor for detecting the pressure of the pressurized fluid in the thrust receiving surface. The thrust receiving surface of the spindle housing is provided with a fluid conduit that opens to the thrust receiving surface and guides fluid pressure to the pressure sensor on the thrust receiving surface. Also. A groove is formed in the thrust receiving surface so as to communicate with an opening of the fluid conduit for guiding fluid pressure from the opening of the fluid conduit for supplying the pressurized fluid to the pressure sensor. The detection member is a tool abnormality detection device provided with a detent for preventing rotation with respect to the spindle housing.
[0010]
The present invention further provides a spindle to which a tool such as a drill is attached, a spindle housing accommodating the spindle, and a spindle in front of the spindle. rear A first bearing located at an end and holding the main shaft rotatably and movably in a thrust direction with respect to the main shaft housing; bearing One between Rotating wheel A second bearing fixed to the spindle housing and loosely fitted to the spindle, and a second bearing provided integrally with the spindle and in a thrust direction. The other rotating wheel of A fluid pipe line formed in the main shaft housing and opened to the main shaft side to supply pressurized fluid, and a flange portion of the main shaft facing the flange portion through a space in a thrust direction. A detecting member fixed to the other rotating wheel of the bearing, and one opening formed in the detecting member communicates with the opening of the fluid conduit of the spindle housing, and the other opening corresponds to the flange of the spindle. A tool abnormality detection device comprising: a facing fluid conduit; and a pressure sensor for detecting a pressure of a pressurized fluid in the fluid conduit formed in the spindle housing.
[0011]
Further, the present invention provides a spindle on which a tool such as a drill is mounted, a spindle housing accommodating the spindle, and a spindle which is located at front and rear ends of the spindle and holds the spindle rotatably and in a thrust direction with respect to the spindle housing. One bearing and this first bearing while And a pair of second bearings that are rotatable and hold the main shaft in the thrust direction, and each inner ring of the pair of second bearings is fixed to the main shaft, and The above second bearing The outer ring is provided so as to be able to move slightly in the thrust direction in a detented state with respect to the spindle housing. The above second bearing The outer ring is supported on the main shaft housing side, and a fluid conduit that opens to the main shaft side and supplies pressurized fluid is formed in the main shaft housing, and is provided between the outer rings of the pair of second bearings. the above Facing the end face of the second bearing on the front side via the space the above A detection member supported by the outer ring of the second bearing on the rear side, and one opening formed in the detection member communicates with the opening of the fluid conduit of the spindle housing; Front second bearing And a pressure sensor for detecting a pressure of a pressurized fluid in the fluid conduit formed in the main shaft housing.
[0012]
[Action]
The tool abnormality detecting device of the present invention improves rigidity by supporting the main shaft with respect to the main shaft housing at three points by a front and rear first bearing and an intermediate second bearing, and furthermore, moves the detection member together with the main shaft in the thrust direction. The thrust force applied to the main shaft can be directly converted to the movement of the detection member when detecting the machining resistance generated when the tool attached to the main shaft is broken or worn, etc. A pressurized fluid is supplied between the detection member and the member facing the same, and the pressure of the pressurized fluid is guided to a pressure sensor to detect the pressure. And other abnormalities are detected.
[0013]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIGS. 1 to 5 show a first embodiment of the present invention. A tool abnormality detecting device according to this embodiment includes a spindle 12 on which a tool 10 such as a drill is attached, and a spindle housing containing the spindle 12. 16 are used for various machine tools having the above. At the front end on the tool 10 side of the main shaft 12 and the rear end on the opposite side, a position in the radial direction is restricted between the main shaft housing 16 and the main shaft 12, and the main shaft 12 and the main shaft 12 are slightly moved in the thrust direction. A pair of bearings 14 and 15 as a first bearing which is a radial bearing such as a movable cylindrical roller bearing is provided. The bearing 14 is fixed to the main shaft housing 16 on the tool 10 side of the main shaft housing 16 with one end of an outer ring 14a abutting against a step 16a of the main shaft housing 16 and the other end of the outer ring 14a being held by a mounting member 18. Have been. The inner ring 14b of the bearing 14 is fixed to the main shaft 12, and is provided so as to be slightly movable with the main shaft 12 in the thrust direction. The bearing 15 has the same configuration as the bearing 14, and has an outer ring 15a fixed to the main shaft housing 16, an inner ring 15b fixed to the main shaft 12, and the main shaft 12 provided to be slightly movable in the thrust direction.
[0014]
Between the bearings 14 and 15 of the main shaft 12, a bearing 20 as a second bearing such as an angular ball bearing capable of receiving a load in the thrust direction is provided. A pair of bearings 20 are provided so as to be able to receive a force in the thrust direction front and rear, and an inner ring 20 b thereof is fixed to the main shaft 12. A metal spacer 17 is fitted between the inner ring 14b of the bearing 14 and the inner ring 20b of the bearing 20, and the inner ring 14b of the bearing 14 comes into contact with the stopper surface 12a of the main shaft 12 on the tool 10 side. The inner ring 20b is fastened and fixed by a nut 19 screwed to the main shaft 12 via a spacer 17. The outer ring 20a is fixed by contacting a step 22a on the inner surface of the bottomed cylindrical detection member 22. The main shaft 12 of the detection member 22 is rotatably and coaxially inserted through a through hole 24 in a cylindrical end surface, and is provided movably with the main shaft 12 in the thrust direction.
[0015]
The detecting member 22 is provided with a long groove 26 formed on the outer surface thereof in the axial direction of the main shaft 12, and the tip of a detent screw 28 screwed to the main shaft housing 16 is located in the long groove 26. Are movable in the thrust direction and are non-rotatably guided. The tip of the detection member 22 is provided to be able to abut at a predetermined position on a shaft retaining ring 23 fixed to the inner wall surface of the spindle housing 16. An interval δr between the detection member 22 and the inner peripheral surface of the main shaft housing 12 is formed to be a gap of about 10 to 20 μm, which allows the passage of the pressurized fluid over the entire circumference. As shown in FIG. 3, grooves 30 formed radially in three directions and through which a pressurized fluid can pass are provided on the outer surface of the end surface of the detection member 22. The depth δh of the groove 30 is about 30 to 40 μm, and is formed from the outer surface to the vicinity of the through hole 24 at the center. As shown by the two-dot chain line in FIG. 1, the groove 30 may be formed with a groove 30 ′ instead of the groove 30 on the thrust receiving surface 32 side of the spindle housing 16. Further, a thrust receiving surface 32 that faces the end surface of the detection member 22 and supports the detection member 22 in the thrust direction is formed on the spindle housing 12. The distance δd between the outer surface of the end surface of the detection member 22 and the thrust receiving surface 32 changes from about 50 μm to less than about 50 μm as the main shaft 12 moves in the thrust direction.
[0016]
The main shaft housing 16 is formed with a fluid conduit 34 that opens to the side surface of the detecting member 22 and is connected to a pressurized air supply source and supplies pressurized air. A concave portion 36 is formed on a side surface of the member 22. In the thrust receiving surface 32 of the main shaft housing 16, near the main shaft 12, an opening 38 d at one end of a fluid conduit 38 formed in the main shaft housing 16 is opened, and the other end of the fluid conduit 38 is It is connected to a pressure sensor 40 such as a semiconductor diaphragm pressure sensor that electrically detects the pressure of the fluid.
[0017]
The operation of the tool abnormality detection device of this embodiment is as follows. After the tool 10 is mounted on the spindle 12 and the work 50 is set, a spindle motor (not shown) is rotated to rotate the spindle 12 at a predetermined rotation speed. Then, the spindle housing 16 is moved toward the work by a slide mechanism and a feed motor (not shown). At this time, pressurized air is supplied to the fluid pipeline 34 from a pressurized air source. Thereby, pressurized air is sent between the detection member 22 in the main shaft housing 16 and the thrust receiving surface 32 of the main shaft housing 16, and functions similarly to a static pressure air bearing. In addition, due to the pressure of the pressurized air, the main shaft 12, the bearing 20, and the inner ring 14b of the bearing 14 move a minute amount toward the tool 10 together with the detection member 22, and come into contact with a stopper (not shown) and stop. As a result, a space having a gap of about 50 μm is formed between the outer surface of the end surface of the detection member 22 and the thrust receiving surface 32. Thus, the pressure detected by the pressure sensor 40 via the fluid conduit 38 indicates a pressure substantially higher than the gauge pressure, similarly to the peripheral surface of the main shaft 12 which is open to the atmospheric pressure.
[0018]
Then, when the tip of the tool 10 abuts on the workpiece 50 and the machining is started, a force acts on the main shaft 12 in the thrust direction due to the machining resistance, and the thrust force acts on the bearing 20 together with the detection member 22 together with the detection member 22. It moves slightly in the opposite direction to the tool 10. This moving distance is about several tens of μm. The pressure drop of the pressurized air from the opening 34a of the fluid line 34 to the opening 38d of the fluid line 38 has a tendency as shown in FIG.
[0019]
That is, as shown in FIGS. 2 and 4, the pressure loss from the point a of the opening 34 a of the fluid conduit 34 to the point b of the end face of the detecting member 22 is changed from the point b of the end face to the groove. The pressure loss from the center end c of the groove 30 to the point c opened to the atmospheric pressure from the center c of the groove 30 is very sharp. This is because the gap between the outer peripheral surface of the detecting member 22 and the inner peripheral surface of the spindle housing 16 is extremely small, 10 to 20 μm, whereas a thrust force is applied between the detecting member end surface and the thrust receiving surface 32. This is because even in the state in which the detection member 22 is closed, an appropriate fluid passage is formed by the groove 30 on the end face of the detection member 22, and the pressure loss is small. The opening 38d of the fluid conduit 38 is located slightly closer to the central end c of the groove 30 than the point d, and the sudden change in pressure between the points cd is determined by the fluid conduit. It is provided so as to be able to transmit to the pressure sensor 40 by 38. If the groove 30 is not provided, the pressure loss of the pressurized air in the flow path abcd tends to decrease uniformly as shown by the broken line in FIG.
[0020]
The feed amount of the tool 10 is controlled by a control device (not shown), and the position and timing at which the tip of the tool 10 abuts on the work 50 are known. A control device (not shown) detects the output of the pressure sensor 40. As shown in FIG. 5, when the tool 10 abuts on the workpiece 50 at time t1 and a thrust force is applied to the main shaft 12, the output of the pressure sensor 40 rises rapidly, and the output of the pressure sensor 40 becomes flat, as shown in FIG. Then, the pressure sensor output becomes almost constant. Here, as shown in FIG. 5, when the thrust force applied to the main shaft 10 is measured by a measuring device such as a strain gauge, a large fluctuation waveform is obtained at a high frequency due to a fluctuation of a processing resistance or the like. Therefore, if the determination of the thrust force is performed based on the measured value of the thrust force, an error increases. However, in this embodiment in which the thrust force is measured via the pressurized air, the pressurized air acts as a damper, and is detected as a smooth curve as shown in the output of the pressure sensor in FIG. It is possible to determine.
[0021]
In order to detect breakage of the tool 10 on the basis of the output of the pressure sensor 40, if the tool 10 is broken, if the tool 10 is normal, the tool 10 is broken even if it has advanced several mm into the work 50. Since the tool 10 has not reached the workpiece, no thrust force acts on the main shaft 12, and the output of the pressure sensor 40 does not rise. Therefore, if a value slightly higher than the output of the pressure sensor 40 before the tool 10 comes into contact with the workpiece 50 is set as the threshold value V1, the breakage can be reliably detected at the time t2 when the tool 10 advances several mm into the workpiece 50. Can be.
[0022]
In addition, when the tool 10 is worn, the machining resistance increases, and the thrust force applied to the main shaft 12 increases. Therefore, when the output of the pressure sensor at the time of steady machining in which the output of the pressure sensor 40 becomes constant becomes equal to or more than the steady output value V2 of the output of the pressure sensor 40 obtained by the tool 10 which has reached the wear limit, it is determined to be worn. It can be set as follows.
[0023]
Further, for example, when the tip of the tool 10 is slightly chipped, the tool 10 comes into contact with the workpiece 10 like a normal tool, and thus cannot be detected by the above-described breakage detection. However, in this case, since the blade of the tool 10 is missing, the machining resistance becomes extremely large, and the thrust force becomes abnormally large. Therefore, by setting a certain threshold value V3 for a large thrust force that cannot be generated by normal machining, it is possible to detect an abnormality such as a chipped tool.
[0024]
The tool abnormality detecting device of this embodiment applies pressurized air between the detection member 22 and the main shaft housing 16, and by the pressurized air pressure between the thrust receiving surface 32 in the main shaft housing 16 and the detection member 22, An output corresponding to the thrust force is obtained to determine a tool abnormality. The output of the pressure sensor 40 is stable, a noise is small, and a detection signal having an extremely good S / N ratio can be obtained. . Therefore, it is possible to accurately detect breakage, wear detection, and abnormality such as chipping of a tool. Further, since the rotation of the detecting member 22 around the main shaft 12 is prevented by the rotation preventing screw 28, even when the detecting member 22 comes into contact with the thrust receiving surface 32, the contact surface is seized by the rotation of the main shaft 12. Nothing.
[0025]
Next, a second embodiment of the present invention will be described with reference to FIGS. Here, the same members as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. The tool abnormality detecting device according to this embodiment includes a thrust receiving surface 32 of the spindle housing 16, an opening portion 34 a of a fluid line 34 connected to a supply source of pressurized air, and a fluid line connected to a pressure sensor 40. The opening 38 d of 38 is provided by being connected by a groove 42. The depth of the groove 42 is about 30 to 40 μm. When the flat end surface of the detecting member 22 is in contact with the thrust receiving surface 32, the pressurized air causes a pressure loss and the opening of the fluid line 38 is opened. It is long enough to be transmitted to the portion 38d.
[0026]
The operation of the tool abnormality detection device of this embodiment is the same as that of the first embodiment. At the beginning of the supply of pressurized air, the detection member 22 is separated from the thrust receiving surface 32 of the spindle housing 16 and the pressure sensor 40 Output is slightly higher than the gauge pressure. When the tool 10 comes into contact with the workpiece 50 and a thrust force is applied, the detection member 22 moves toward the thrust receiving surface 32 of the spindle housing 16 and closes the openings 34a and 38d of the fluid conduits 34 and 38. To position. As a result, the pressurized air is transmitted from the opening 34 a of the fluid conduit 34 to the opening 38 d of the fluid conduit 38 through the groove 42. At this time, the proximity state of the detection member 22 to the thrust receiving surface 32 differs due to the thrust force, and the output of the pressure sensor 40 differs similarly to the above embodiment. That is, when the thrust force is small, the space between the detection member 22 and the thrust receiving surface 32 is relatively wide, and the pressure detected by the pressure sensor 40 is relatively small. Further, when the processing resistance is large and the thrust force is large, the interval becomes narrow, the pressure escaping to the atmosphere side decreases, and the pressure transmitted to the pressure sensor 40 increases. Thereby, breakage, wear, chipping, and the like of the tool 10 can be accurately detected.
[0027]
The same effects as those of the first embodiment can be obtained by the tool abnormality detection device of this embodiment, and the structure of the detection member 22 and the like can be simplified.
[0028]
Next, a third embodiment of the present invention will be described with reference to FIG. Here, the same members as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. The tool abnormality detecting device of this embodiment is mounted on the spindle housing 16 via a mounting member 45. One of the wheels is A bearing 44 such as a thrust ball bearing which is fixed and holds the main shaft 12 in the thrust direction is provided. The main shaft 12 is integrally provided with a flange portion 46 facing the bearing 44 in the thrust direction. Further, a fluid conduit 48 that opens to the main shaft 12 side to supply pressurized air and is also connected to the pressure sensor 40 is formed in the main shaft housing 16. This pressurized air is connected to a fluid line 48 via a throttle 41 before a junction with the fluid line on the pressure sensor 40 side, and is connected to a bearing 44. The other A ring-shaped detection member 52 facing the flange portion 46 on the main shaft 12 side in the thrust direction is fixed to the rotating wheel 44b. A fluid conduit 54 is formed in the detecting member 52, and one opening 54 a faces the opening 48 a of the fluid conduit 48 of the main shaft housing 16, and the other opening 54 b is a flange portion on the main shaft 12 side. 46 faces the end face.
[0029]
The operation of the tool abnormality detection device of this embodiment is the same as that of the first embodiment. At the beginning of the supply of pressurized air, the flange portion in which pressurized air is provided on the main shaft 12 from the fluid line 54 of the detection member 52 The flange portion 46 is separated from the detection member 52 by about several tens of μm together with the main shaft 12, and the output of the pressure sensor 40 is slightly higher than the gauge pressure. When the tool 10 comes into contact with the workpiece 50 and a thrust force is applied, the flange 46 closes the opening 54 b of the fluid conduit 54 of the detection member 52. At this time, although the flange portion 46 is rotating at a high speed integrally with the main shaft 12, the detection member 52 is provided on the bearing 44, and thus supports the main shaft 12 in the thrust direction while rotating.
[0030]
Then, the pressure from the pressurized air supply source is directly applied to the pressure sensor 40 by the flange 46 closing the opening 54b of the fluid conduit 54 of the detection member 52, and the pressure is detected. Therefore, for example, if the pressure is detected at a position several millimeters after the normal tool 10 contacts the workpiece 50, the pressure detected by the pressure sensor 40 increases in a normal case. On the other hand, in the case of a broken tool, the thrust force does not act because the broken tool is not in contact with the work at that position, and the opening portion 54b of the fluid conduit 54 is not closed by the flange portion 46. Therefore, the pressure applied to the pressure sensor 40 does not increase, and breakage of the tool is detected.
[0031]
As with the first embodiment, the tool abnormality detection device of this embodiment can detect relatively little noise.
[0032]
Next, a fourth embodiment of the present invention will be described with reference to FIGS. Here, the same members as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. The tool abnormality detection device of this embodiment is provided with a pair of second bearings 60, 61 such as angular ball bearings that rotatably hold the main shaft 12 in the thrust direction. The bearings 60, 61 are respectively provided with inner rings 60b, 61b is fixed to the main shaft 12 by tightening the spacer 17 and the nut 63. The outer ring 61a of the bearing 61 abuts the step 16b of the main shaft housing 16, and a ring-shaped detection member 62 abuts on the front end face of the outer ring 61a. A compression spring 65 is provided between the outer ring 60a of the bearing 60 and the detection member 62, and the action thereof constantly presses the detection member 62 and the outer ring 61a toward the step 16b of the main shaft housing 16. A gap δ is formed between the outer ring 60a and the detection member 62. The outer ring 60a is prevented from rotating by the rotation preventing screw 28, and is supported so as to be slightly movable in the thrust direction together with the main shaft 12. A fluid conduit 64 is formed in the detection member 62, and one opening 64 a faces the opening 66 a of the fluid conduit 66 of the main shaft housing 16, and the other opening 64 b moves in the thrust direction together with the main shaft 12. The possible bearing 60 is open toward the end face of the outer ring 60a. The fluid line 66 is connected to the pressurized air supply source and is also connected to the pressure sensor 40.
[0033]
The operation of the tool abnormality detecting device of this embodiment is the same as that of the third embodiment. At the beginning of the supply of the pressurized air, the bearing 60 in which the pressurized air is provided to the main shaft 12 from the fluid line 64 of the detecting member 62. The main shaft 12 is separated from the detection member 62 by about several tens of μm together with the bearing 60, and the output of the pressure sensor 40 is slightly higher than the gauge pressure. When the tool 10 comes into contact with the workpiece 50 and a thrust force is applied, the bearing 60 together with the main shaft 12 comes into contact with the end face of the detection member 62 and closes the opening 64 b of the fluid conduit 64 of the detection member 62. As a result, the opening 64b of the fluid conduit 64 is closed, and the pressure from the pressurized air supply source is directly applied to the pressure sensor 40, and the pressure is detected. Therefore, for example, if the pressure is detected at a position several millimeters after the normal tool 10 contacts the workpiece 50, the detected pressure of the pressure sensor 40 increases. On the other hand, in the case of a broken tool, the thrust force does not act because the broken tool is not in contact with the work at that position, and the opening 64b of the fluid conduit 64 of the detection member 62 is not closed by the bearing 60. Accordingly, the pressure applied to the pressure sensor 40 does not increase, and a predetermined output cannot be obtained, so that the breakage of the tool is detected.
[0034]
The same effects as in the third embodiment can be obtained by the tool abnormality detection device of this embodiment, and the mounting structure of the detection member 62 and the bearings 60, 61 can be simplified.
[0035]
Note that, in addition to the above-described embodiments, the present invention may use oil as the pressurized fluid in each embodiment, and has the effect of simultaneously lubricating the bearing by using oil.
[0036]
【The invention's effect】
Since the tool abnormality detecting device of the present invention detects the thrust force applied to the main shaft by the pressure sensor via the pressurized fluid, it is hardly affected by the variation of the thrust force due to the variation of the machining resistance and the like, and the S / N Detection with a good ratio is possible. Therefore, the abnormality of the tool can be detected with high accuracy, and there are many types of abnormalities that can be detected.
[Brief description of the drawings]
FIG. 1 is a schematic vertical sectional view of a first embodiment of a tool abnormality detecting device according to the present invention.
FIG. 2 is a partially enlarged longitudinal sectional view of a bearing and a detecting member according to the first embodiment of the present invention.
FIG. 3 is a front view of the detection member according to the first embodiment of the present invention.
FIG. 4 is a graph showing pressure loss in a pressurized fluid path according to the first embodiment of the present invention.
FIG. 5 is a graph showing the output of the pressure sensor according to the first embodiment of the present invention and the thrust force applied to the main shaft.
FIG. 6 is a schematic longitudinal sectional view of a bearing and a detecting member according to a second embodiment of the present invention.
FIG. 7 is a front view of a thrust receiving surface of a spindle housing according to a second embodiment of the present invention.
FIG. 8 is a schematic vertical sectional view of a third embodiment of the tool abnormality detecting device according to the present invention.
FIG. 9 is a schematic vertical sectional view of a fourth embodiment of the tool abnormality detecting device according to the present invention.
FIG. 10 is a partially enlarged longitudinal sectional view of a fourth embodiment of the tool abnormality detecting device according to the present invention.
[Explanation of symbols]
10 Tools
12 spindle
14, 15, 20, 44, 60, 61 bearings
16 Spindle housing
22, 52, 62 detecting member
32 Thrust receiving surface
34, 38, 48, 54, 64, 66 Fluid lines
40 pressure sensor

Claims

A main shaft to which a tool is attached, a main shaft housing accommodating the main shaft, and a first bearing located at front and rear ends of the main shaft and supporting the main shaft so as to be rotatable and movable in the thrust direction with respect to the main shaft housing, A second bearing that is located between the first bearings and has an inner ring fixed to the main shaft and rotatably holds the main shaft in the thrust direction between the inner ring and the outer ring, and the main shaft between the main shaft and the main shaft housing. On the other hand, a detecting member rotatably fitted to the main shaft housing so as to be movable in the thrust direction and having an outer ring of the second bearing fixed thereto and receiving a thrust force, and an end face and space of the detecting member opposite to the tool. A thrust receiving surface provided on the main shaft housing and opposed to each other via a portion, a fluid conduit for supplying pressurized fluid to the space, and a pressure of the pressurized fluid at the thrust receiving surface. Tool abnormality detecting device that includes a pressure sensor for detecting a.

A main shaft to which a tool is attached, a main shaft housing accommodating the main shaft, and a first bearing located at front and rear ends of the main shaft and supporting the main shaft so as to be rotatable and movable in the thrust direction with respect to the main shaft housing, A second bearing that is located between the first bearings and has an inner ring fixed to the main shaft and rotatably holds the main shaft in the thrust direction between the inner ring and the outer ring, and the main shaft between the main shaft and the main shaft housing. On the other hand, a detecting member rotatably fitted to the main shaft housing so as to be movable in the thrust direction and having an outer ring of the second bearing fixed thereto and receiving a thrust force, and an end face and space of the detecting member opposite to the tool. A thrust receiving surface provided on the spindle housing and opposed to each other via a portion, a pressure sensor for detecting a pressure of a pressurized fluid on the thrust receiving surface, and the spindle housing A first fluid conduit that opens at a position facing the side surface of the detection member and supplies the pressurized fluid, and a second fluid channel that opens to the thrust receiving surface of the spindle housing and constantly guides fluid pressure to a pressure sensor. A tool abnormality detecting device including a fluid conduit, wherein a gap through which the pressurized fluid can pass from the opening of the first fluid conduit to the space between the main spindle housing and the detection member is formed. .

The tool abnormality detection according to claim 2, wherein a groove through which the pressurized fluid can pass from the gap toward the second fluid conduit is formed on an end surface of the detection member facing the thrust receiving surface. apparatus.

The tool abnormality detecting device according to claim 2, wherein a groove through which the pressurized fluid can pass from the gap toward the second fluid conduit is formed on the thrust receiving surface facing the detection member.

5. The tool abnormality detecting device according to claim 1, wherein said detecting member is provided with a detent for preventing rotation with respect to said spindle housing.

A main shaft to which a tool is attached, a main shaft housing accommodating the main shaft, and a first bearing located at front and rear ends of the main shaft and supporting the main shaft so as to be rotatable and movable in the thrust direction with respect to the main shaft housing, A second bearing that is located between the first bearings and has an inner ring fixed to the main shaft and rotatably holds the main shaft in the thrust direction between the inner ring and the outer ring, and the main shaft between the main shaft and the main shaft housing. On the other hand, a detecting member rotatably fitted to the main shaft housing so as to be movable in the thrust direction and having an outer ring of the second bearing fixed thereto and receiving a thrust force, and an end face and space of the detecting member opposite to the tool. A thrust receiving surface provided on the main shaft housing to face through the portion, a fluid conduit opening to the thrust receiving surface and supplying a pressurized fluid to the space, Tool abnormality detecting device provided with a pressure sensor for detecting the pressure of the pressurized fluid in the preparative receiving surface.

7. The tool abnormality detecting device according to claim 6, further comprising a fluid conduit opened to the thrust receiving surface of the spindle housing and guiding the fluid pressure to the pressure sensor on the thrust receiving surface.

8. The tool abnormality according to claim 7, wherein a groove is formed in the thrust receiving surface, the groove communicating with an opening of the fluid conduit for guiding fluid pressure from the opening of the fluid conduit for supplying the pressurized fluid to the pressure sensor. Detection device.

9. The tool abnormality detecting device according to claim 6, wherein the detecting member is provided with a detent for preventing rotation with respect to the spindle housing.

A main shaft tool is attached, a spindle housing containing the main axis, a first bearing located at the end portion before and after of the spindle relative to the spindle housing and movably holds the spindle freely and in the thrust direction rotation A second bearing positioned between the first bearing and one of the rotating wheels fixed to the spindle housing and loosely fitted to the spindle; and a second bearing provided integrally with the spindle and in a thrust direction. A flange portion facing the other rotating wheel , a fluid conduit formed in the main shaft housing and opened to the main shaft side to supply pressurized fluid, and a flange portion of the main shaft and a space portion in a thrust direction through a space portion. A detecting member facing and fixed to the other rotating wheel of the second bearing, one opening formed in the detecting member communicates with the opening of the fluid conduit of the main shaft housing, and the other opening is Main shaft Tool abnormality detecting device provided with a fluid conduit facing the Nji portion, and a pressure sensor for detecting the pressure of the pressurized fluid of the spindle housing which is formed in the fluid conduit.

A main spindle to which a tool is attached, a main spindle housing accommodating the main spindle, a first bearing located at front and rear ends of the main spindle and rotatably holding the main spindle in the thrust direction with respect to the main spindle housing; A pair of second bearings that are located between the bearings and rotatably hold the main shaft in the thrust direction, and each inner ring of the pair of second bearings is fixed to the main shaft, and the front side second The outer ring of the bearing is provided so as to be detented and slightly movable in the thrust direction with respect to the main shaft housing, and the outer ring of the second bearing on the rear side is supported on the main shaft housing side, and is opened on the main shaft side. a fluid conduit for supplying the pressurized fluid formed in the spindle housing Te, face each other through an end face and a space portion of the front side of the second bearing provided between the outer race of the pair of second bearing the rear A sensing member which is supported by the outer ring of the second bearing side, the opening of one formed in the detection member and the other opening communicating with the opening of the fluid conduit of the spindle housing of the front side A tool abnormality detecting device comprising: a fluid conduit facing an end face of an outer ring of a second bearing ; and a pressure sensor for detecting a pressure of a pressurized fluid in the fluid conduit formed in the main shaft housing.