JP3613753B2

JP3613753B2 - Spindle device and rolling bearing preload method

Info

Publication number: JP3613753B2
Application number: JP07103399A
Authority: JP
Inventors: 直弘池田
Original assignee: Niigata Machine Techno Co Ltd
Current assignee: Niigata Machine Techno Co Ltd
Priority date: 1999-03-16
Filing date: 1999-03-16
Publication date: 2005-01-26
Anticipated expiration: 2019-03-16
Also published as: JP2000266046A

Description

【０００１】
【発明の属する技術分野】
本発明は、工作機械の主軸等のころがり軸受に予圧をかける軸受予圧用油圧回路及び主軸装置並びにころがり軸受の予圧方法に関する。
【０００２】
【従来の技術】
図７に示すように、ハウジング６１内に、主軸６２をタンデム配置の前後２組のころがり軸受６３，６４で回転自在に支持した工作機械の主軸装置においては、一般に、ころがり軸受６３，６４の外輪の間にそれらに予圧を付加して間座６５を組み込むことが行われている。
【０００３】
この予圧方式はシンプルであるが、図８のように、高速回転で軸受予圧が急上昇して焼付きに至るため（予圧Ａ曲線）、回転数ｎＢまで運転するには組込み時に停止時予圧ＰＡが与えられず、組込み時に予圧が抜けてガタになる予圧ＰＢの予圧Ｂ曲線を取らなければならない。このため、低速回転時に主軸剛性がなく、切削能力が劣ってしまうことになる。
【０００４】
そこで、実公平４−５３４５７号公報と特許第２５２８２３６号公報において、次のような主軸装置が提案されている。
【０００５】
（実公平４−５３４５７号公報）
この主軸装置は、図９に示すように、ハウジング６１内に、主軸６２を、前後２組のころがり軸受６３，６４で回転自在に支持した主軸装置であって、ころがり軸受６３の外輪に嵌着されてハウジング６１の後端部に主軸６２の軸方向に移動自在に嵌挿された可動スリーブ部材６６と、ハウジング６１に形成された油圧室Ｒｒ内に軸方向に移動自在に装入され、介在部材６７を介して可動スリーブ部材６６を後側（図９で右側）に移動させてころがり軸受６３の外輪に予圧をかけるピストン部材６８と、可動スリーブ部材６６を後側に付勢してころがり軸受６３の外輪に予圧をかける予圧ばね６９と、介在部材６７を介してピストン部材６８を前側に押し戻す戻しばね７０とを備え、図１０に示すように、主軸６２の低速回転時には、油圧回路（図示せず）から油圧室Ｒｒに作動油を供給してピストン部材６８と予圧ばね６９とで可動スリーブ部材６６を後側に押して定位置予圧を行い、また高速回転時には、予圧ばね６９のみで可動スリーブ部材６６を押して定圧予圧を行うことができる構造となっている。
【０００６】
（特許第２５２８２３６号公報）
この主軸装置は、図１１に示すように、ハウジング６１内に、主軸６２を、前後２組のころがり軸受６３（前側のころがり軸受は図示されていない。）で回転自在に支持した主軸装置であって、ころがり軸受６３の外輪に嵌着されてハウジング６１の後端部に主軸６２の軸方向に移動自在に嵌挿された可動スリーブ部材６６と、油圧室Ｒｓ，Ｒｔ内に軸方向に移動自在に装入され、可動スリーブ部材６６を後側（図１１で右側）に移動させてころがり軸受６３の外輪に予圧をかけるピストン部材６８と、ハウジング６１に取り付けられ、可動スリーブ部材６６とピストン部材６８の移動量を制限する調整部材７２とを備え、図１２のように、定位置予圧を３段に切り換え、低速時の予圧を高めて焼付き限界内に推移させることができるようになっている。
符号７３は、油圧室Ｒｓ，Ｒｔに作動油を供給する油圧回路であり、油圧ポンプ７４を主体とする。
【０００７】
なお、図１２において、δ１はころがり軸受６３の初期隙間（初期隙間の総和）、δ２は調整部材７２と可動スリーブ部材６６の間に形成される隙間、δ３は調整部材７２とピストン部材６８の間に形成される隙間である。
【０００８】
【発明が解決しようとする課題】
しかし、上記の主軸装置には次のような問題点がある。
（実公平４−５３４５７号公報）
（イ）高速回転設定の定圧予圧時に、切削力により主軸６２が予圧ばね６９のばね力よりも大きい力で引っ張られると、主軸６２が動き、振れ回ることでころがり軸受に損傷を与える。
【０００９】
（ロ）定圧予圧量を定位置予圧量よりも大きく設定できない。小さなばね力の定圧予圧時は切削能力が低下してしまう。
（ハ）プッシュロッドを主軸６２の後部から前に押して工具の把持を解く構造の主軸装置の場合、プッシュロッドの操作時に主軸６２が前に出てしまう。
（ニ）高速（定圧予圧）と低速（定位置予圧）の２段しか切り換えられない。
【００１０】
（特許第２５２８２３６号公報）
（ホ）全域定位置予圧方式であるため、回転数を高くするほど高速回転側の予圧設定「予圧Ｃ曲線」になるが、組込み時に予圧抜けする量が増える。
（ヘ）高速回転設定で回転指令を与えると、低速回転時に予圧抜けしているため、加速・減速時にころがり軸受６３のボールがスリップを起こして発熱を生じたり、回転がガタつくなどの現象を生じる。
【００１１】
（ト）高速回転側では停止時に予圧抜けで主軸６２がガタつき、振れ精度がでない。
（チ）予圧を高めた後に、予圧を下げる操作を行っても可動スリーブ部材６６のＯリングが抵抗となり動きが悪い。
（リ）予圧切換えの段数を多くするほど組込みスペースが長く必要になる。
【００１２】
また、いずれかの主軸装置も、油圧ポンプ７４（図１１）で作動油を油圧室に供給する構造となっているが、油流量が非常に少なく、油圧の圧力調整弁では、油の流れがある程度生じないと圧力が変化しにくいため、幾つかの圧力調整弁をセットして切り換えて圧力制御することになり、連続可変にできない。
【００１３】
本発明は、上記に鑑みてなされたもので、主軸装置及びその主軸装置における合理的なころがり軸受の予圧方法を提供することを目的とする。
【００１９】
【課題を解決するための手段】
上記の目的を達成するために、請求項１記載の発明は、ハウジング内に、主軸が、ころがり軸受で回転自在に支持された主軸装置において、上記ころがり軸受の外輪に嵌着されるとともに戻し用油圧室を形成して上記ハウジングに主軸の軸方向に移動自在に嵌挿された可動スリーブ部材と、予圧用後側油圧室を有し、上記可動スリーブ部材の前端部に一体に固定された押圧部材と、上記予圧用後側油圧室内に軸方向に移動自在に装入され、上記押圧部材を後側に移動させて上記ころがり軸受の外輪に予圧をかける後側ピストン部材と、上記押圧部材の前端部に固定され、上記後側ピストン部材の前側への移動を阻止する後側ストッパ部材と、予圧用前側油圧室を有し、該予圧用前側油圧室を上記予圧用後側油圧室に向き合わせてハウジングに一体に固定された固定スリーブ部材と、上記予圧用前側油圧室内に軸方向に移動自在に装入された前側ピストン部材と、上記固定スリーブ部材の後端部に上記後側ストッパ部材に向き合わせて設けられ、上記前側ピストン部材の後側への移動を阻止する前側ストッパ部材と、上記後側ピストン部材と前側ピストン部材との間及び上記押圧部材と固定スリーブ部材との間に軸方向に移動自在に設けられた中間部材と、上記後側ストッパ部材と前側ストッパ部材の部分にそれらの間隔が大きくなるように付勢して設けられた予圧ばねとを具備した構成とした。
【００２０】
この手段では、戻し用油圧室を脱圧状態にして予圧用後側油圧室と予圧用前側油圧室に油圧回路から作動油を供給すると、後側ピストン部材と前側ピストン部材とが油圧力により後側ストッパ部材と前側ストッパ部材とにそれぞれ強く押し付けられ、中間部材を介して可動スリーブ部材と固定スリーブ部材を突っ張る。油圧力を最大切削スラスト力よりも充分大きくすることで、切削力が主軸に作用しても両ピストン部材が動くことはなく、定位置の重予圧に相当する性能が得られる。
【００２１】
また、戻し用油圧室と予圧用後側油圧室を脱圧状態にし、予圧用前側油圧室に作動油を供給して前側ピストン部材に最大切削スラスト力以上の油圧力を作用させると、前側ピストン部材が中間部材を介し押圧部材を強く押して前側ストッパ部材に押し付けられ、ころがり軸受に予圧を付加する。この場合は、中間部材が押圧部材に当接してそれらの間の隙間をなくしており、タンデム配置のころがり軸受の外輪スパンが上記の隙間分短くなっている結果、定位置の中予圧となる。
【００２２】
また、戻し用油圧室と予圧用前側油圧室を脱圧状態にし、予圧用後側油圧室に作動油を供給して後側ピストン部材に最大切削スラスト力以上の油圧力を作用させると、後側ピストン部材が中間部材を固定スリーブ部材に押し付けて後側ストッパ部材に押し付けられ、押圧部材を可動スリーブ部材側に動かしてころがり軸受に定位置の予圧を加える。
また、予圧用前側油圧室を脱圧状態にし、戻し用油圧室と予圧用後側油圧室に油圧回路から作動油を供給した状態では、油圧力と予圧ばねのばね力がころがり軸受の予圧に働く。この場合は、定圧予圧となる。
【００２３】
なお、前側ピストン部材等の「前側」は、通常、工具が装着される主軸の先端側であり、「後側」はその反対側であるが、絶対的なものではなく、見る方向によって変わるので、上記の逆に解釈することもできる。
【００２４】
上記の主軸装置において、戻し用油圧室の受圧面積よりも予圧用後側油圧室の受圧面積を大きくすることができる（請求項２）。
この構成では、戻し用油圧室と予圧用後側油圧室に同一圧力の作動油を供給した場合、戻し用油圧室と予圧用後側油圧室の受圧面積差に対応した力が働いて予圧を高める。したがって、戻し用油圧室と予圧用後側油圧室の油圧回路を同一にすることが可能となる。
【００２５】
また、後側ピストン部材が後側ストッパ部材と中間部材とに当接するとともに、前側ピストン部材が前側ストッパ部材と中間部材とに当接した状態における、押圧部材と中間部材との間の隙間よりも固定スリーブ部材と中間部材との間の隙間を大きくした構成とすることができる（請求項３）。
この構成では、戻し用油圧室と予圧用前側油圧室を脱圧状態にして予圧用後側油圧室に作動油を供給した場合、中間部材が固定スリーブ部材に隙間を無くして当接し、タンデム配置のころがり軸受の外輪スパンが、戻し用油圧室と予圧用後側油圧室とを脱圧状態にして予圧用前側油圧室に作動油を供給した時の外輪スパンよりも小さくなっているので、最低の定位置予圧となる。
【００２６】
また、請求項１ないし３のいずれか１つに記載の主軸装置において、油圧室に作動油を供給してピストン部材でころがり軸受の外輪を押圧する軸受予圧用油圧回路が、空圧源と、該空圧源の空気圧を油圧に変換して作動油をノンリーク形切換弁が設けられた油管路を通じて油圧室に供給するエアオイルブースタと、上記空圧源に上記エアオイルブースタを連絡した空気管路に設けられ、空圧源によるエアオイルブースタの加圧と脱圧を切り換える電磁方向切換弁とを具備することが望ましい（請求項４）。
この構成では、電磁方向切換弁を加圧状態にすると、空圧源の空気圧によってエアオイルブースタが作動し、作動油を油圧室に供給する。また、電磁方向切換弁を脱圧に切り換えると、エアオイルブースタの脱圧によって油圧室が脱圧状態となる。エアオイルブースタは、空気の受圧面積と作動油の加圧面積の差により、空気源から与えられた空気圧を油圧に変換（通常は増圧）するが、作動油の使用流量が微量（例えば、０．００５〜１．５ｃｃ）でも圧力を確実に調整できるため、無段階の連続的な圧力調整を可能とする上、油圧室の圧力が異常に上昇したような場合、空気のクッション作用によって上昇圧力を吸収する。このような軸受予圧用油圧回路の機能を生かして請求項１ないし３のいずれかに記載の主軸装置のころがり軸受に予圧を付加する。ノンリーク形切換弁で油管路を閉じて、例えば、可動スリーブ部材を固定することにより、工具交換時における主軸の変位を抑えてガタつきを防ぐことが可能になる。
【００２７】
また、請求項１ないし３のいずれか１つに記載の主軸装置において、戻し用油圧室と予圧用後側油圧室に作動油を供給してピストン部材でころがり軸受の外輪を押圧する軸受予圧用油圧回路を、空圧源と、該空圧源の空気圧を油圧に変換して作動油をノンリーク形切換弁が設けられた油管路を通じて油圧室に供給するエアオイルブースタと、上記空圧源に上記エアオイルブースタを連絡した空気管路に設けられ、空圧源によるエアオイルブースタの加圧と脱圧を切り換える電磁方向切換弁とを具備した油圧回路とし、予圧用前側油圧室に作動油を供給する油圧回路を、油圧源の油管路に減圧弁と電磁方向切換弁が設けられた油圧回路とすることができる（請求項５）。
この構成では、上記軸受予圧用油圧回路から、戻し用油圧室と予圧用後側油圧室に作動油を供給し、また予圧用前側油圧室に油圧源を持つ別の油圧回路から作動油を供給して、請求項１ないし３のいずれかに記載された主軸装置のころがり軸受に予圧を付加する。ノンリーク形切換弁で油管路を閉じて、例えば、可動スリーブ部材を固定することにより、工具交換時における主軸の変位を抑えてガタつきを防ぐことが可能になる。
【００２８】
請求項６記載の発明は、請求項４又は５記載の主軸装置におけるころがり軸受の予圧方法であって、エアオイルブースタから作動油を油管路を通じて油圧室に供給した後、ノンリーク形切換弁を閉じて定位置予圧を行う構成とした。
この手段では、油圧室内の作動油の非圧縮性によって、例えば、可動スリーブ部材や後側ピストン部材を固定することが可能となる。
【００２９】
【発明の実施の形態】
本発明の実施の形態を添付図面を参照して説明する。
図１ないし図６は本発明の実施の形態を示すもので、符号１は主軸装置である。主軸装置１は、ハウジング３と、主軸４と、ころがり軸受５，６と、可動スリーブ部材７と、押圧部材８と、後側ピストン部材９と、後側ストッパ部材１０と、固定スリーブ部材１２と、前側ピストン部材１３と、前側ストッパ部材１４と、中間部材１６と、予圧ばね１７と、モータ１８とを具備し、油圧回路１９，２０（図５）によってころがり軸受に予圧を付加することができるようになっている。
【００３０】
ハウジング３は、油通路３ａ，３ｂ，３ｃを有する。主軸４は、ハウジング３内に、タンデム配置の２組のころがり軸受５，６によって周方向に回転自在に支持されている。可動スリーブ部材７は、円筒形状とされており、後側（図１で右側）の一対のころがり軸受５の外輪に嵌着されるとともに円環状の戻し用油圧室Ｒａを形成してハウジング３に主軸４の軸方向に移動自在に嵌挿されている。戻し用油圧室Ｒａは、ハウジング３の油通路３ａに直接連通されている。可動スリーブ部材７には、ハウジング３の油通路３ｂに連通する油通路７ａが形成されている。
【００３１】
押圧部材８は円環状とされ、可動スリーブ部材７の前端部に多数のボルト１１ａ（図１には１本しか示されていない。）で一体に固定されている。押圧部材８には、円環状の予圧用後側油圧室Ｒｂと、該予圧用後側油圧室Ｒｂを可動スリーブ部材７の油通路７ａに連通させる油通路８ａと、ころがり軸受５の外輪を押圧する押圧部８ｂとが設けられている。予圧用後側油圧室Ｒｂには、円環状の後側ピストン部材９が主軸４の軸方向に移動自在に液密に装入されている。また、押圧部材８の前端部には後側ストッパ部材１０が多数のボルト１１ｂ（この場合も図１には１本しか示されていない。）で一体に固定され、後側ピストン部材９の前側への移動を阻止している。
【００３２】
固定スリーブ部材１２は円筒形状に形成され、前側の一対のころがり軸受６の外輪に嵌着されてハウジング３に一体に固定されている。固定スリーブ部材１２には、円環状の予圧用前側油圧室Ｒｃと、該予圧用前側油圧室Ｒｃをハウジング３の油通路３ｃに連通させる油通路１２ａが設けられている。予圧用前側油圧室Ｒｃには、円環状の前側ピストン部材１３がこれも主軸４の軸方向に移動自在に液密に装入されている。また、固定スリーブ部材１２の後端部には前側ストッパ部材１４が後側ストッパ部材１０に向き合わせて多数のボルト１１ｃ（図１には１本しか示されていない。）で一体に固定され、前側ピストン部材１３の後側への移動を阻止している。
【００３３】
中間部材１６は円環状に形成され、後側ピストン部材９と前側ピストン部材１３との間及び押圧部材８と固定スリーブ部材１２との間に両ストッパ部材１０，１４に案内されて主軸４の軸方向に移動自在に設けられている。また、予圧ばね１７は、後側ストッパ部材１０と前側ストッパ部材１４との間にそれらの間隔が大きくなるように付勢して設けられている。予圧ばね１７には、コイルばねや板ばね等が、主軸４と同心状に、或いは所定の角度間隔で配置して用いられる。
【００３４】
なお、戻し用油圧室Ｒａの受圧面積Ａ1 よりも予圧用後側油圧室Ｒｂの受圧面積Ａ2 が大きく設定され、また、後側ピストン部材９が後側ストッパ部材１０と中間部材１６とにそれぞれ当接するとともに、前側ピストン部材１３が前側ストッパ部材１４と中間部材１６とにそれぞれ当接した状態においては、押圧部材８における予圧用後側油圧室Ｒｂの内径側前端面と中間部材１６の後端面との間に隙間Δ１があけられ、固定スリーブ部材１２における予圧用前側油圧室Ｒｃの内径側後端面と中間部材１６の前端面との間に隙間Δ 2 があけられるようになっており、上記隙間Δ１よりも上記隙間Δ2 が大きく設定されている。
【００３５】
モータ１８は主軸４を回転させるものであり、ステータ１８ａによって回転させられるロータ１８ｂのロータスリーブに主軸４を嵌挿して、ハウジング３内のころがり軸受５と軸受２１との間に設けられている。符号２２は固定スリーブ部材１２の前端面に一体に固定された押え部材、２３は可動スリーブ部材７の動きを良くしているボールガイドである。
【００３６】
油圧回路１９は、戻し用油圧室Ｒａと予圧用後側油圧室Ｒｂに作動油をそれぞれ供給するものであり、空圧源２５と、エアオイルブースタ２６と、電空レギュレータ（電磁空圧レギュレータ）２７と、一対の電磁方向切換弁２８と、一対の電磁比例流量制御弁２９と、一対のノンリーク形切換弁（電磁切換弁）３０と、一対の圧力センサ３１とを有する。
【００３７】
空圧源２５はコンプレッサ等から成る。エアオイルブースタ２６は、受圧面積の大きい空圧シリンダ２６ａに加圧面積の小さい油圧シリンダ２６ｂを一体に連結して成り、受圧面積と加圧面積の差により、与えられた空気圧を油圧に変換・増圧するもので、空圧シリンダ２６ａを空気源２５に空気管路３３で接続して設けられている。電空レギュレータ２７は、ＮＣ装置等の制御装置（図示せず）からの電圧式又は電流式の外部指令にしたがって空気圧を調整するものであり、空気管路３３に設けられている。
【００３８】
電磁方向切換弁２８は、励磁状態で空気管路３３を空圧シリンダ２６ａのボトム側空気室に連絡するとともに、空圧シリンダ２６ａのロッド側空気室を大気に開放してエアオイルブースタ２６を作動させ、また、消磁状態で空圧シリンダ２６ａのロッド側空気室に空気管路３３を連絡するとともに、ボトム側空気室を大気に開放してエアオイルブースタ２６を脱圧状態にするもので、空気管路３３の分岐管３３ａ，３３ｂにそれぞれ設けられている。
【００３９】
各電磁比例流量制御弁２９と各ノンリーク形切換弁３０及び各圧力センサ３１は、エアオイルブースタ２６の油圧シリンダ２６ｂにそれぞれ接続された油管路３４，３５に、上流側から下流側に上記の順でそれぞれ設けられている。各ノンリーク形切換弁３０は、油管路３４，３５をそれぞれ開閉するものである。圧力センサ３１の出力信号は、前記制御装置に入力され、電空レギュレータ２７のフィードバック制御に利用されるようになっている。油管路３４はハウジング３の油通路３ａに接続され、他の油管路３５はハウジング３の油通路３ｂに接続されている。
【００４０】
油圧回路２０は、予圧用前側油圧室Ｒｃに作動油を提供するものであり、油圧ポンプ等の油圧源３７の油管路３８に、減圧弁３９と電磁方向切換弁４０を設けて成る。油管路３８は、ハウジング３の油通路３ｃに接続されている。
【００４１】
減圧弁３９には、前記油圧室Ｒｃの受圧面積Ａ３に作用する油圧を予め設定する。この設定圧力は、主軸４への逆スラスト力（主軸４が前側に引き抜かれる向きの力）に充分耐えうる圧力とされる。例を挙げると、
許容逆スラスト力Ｆａ＝１００００Ｎ
なら、
油圧力Ｐ１＝（Ｆａ／Ａ３）×１．５〜２として、
Ａ３＝５０ｃｍ^２
なら、
Ｐ１＝３００〜４００Ｎ／ｃｍ^２（３〜４Ｍｐａ）
となる。
一般に油圧源３７は、５Ｍｐａ以上なので減圧弁３９で圧力を下げる。油圧室Ｒｃに流れる作動油量が少なく、可変にしても圧力追従が悪いので、減圧弁３９の設定圧力は１種類に固定するのが普通である。
【００４２】
電磁方向切換弁４０は、ソレノイドａが励磁されると、油管路３８の油圧源３７側を閉じるとともに、油通路３ｃ側を油タンク４１に接続して予圧用前側油圧室Ｒｃを脱圧状態にし、またソレノイドｂが励磁されると（ソレノイドａは消磁）、油管路３８を開いて作動油を予圧用前側油圧室Ｒｃに供給し、更に両ソレノイドａ，ｂが消磁された中立位置で油管路３８を閉じるようになっている。
【００４３】
次に、上記の構成とされた主軸装置の作用を説明する。
図１は、油圧回路１９の分岐管３３ａの電磁方向切換弁２８のソレノイドを消磁して戻し用油圧室Ｒａを脱圧するとともに、他の分岐管３３ｂの電磁方向切換弁２８のソレノイドを励磁して作動油を予圧用後側油圧室Ｒｂに供給し、また油圧回路２０の電磁方向切換弁４０のソレノイドｂを励磁して予圧用前側油圧室Ｒｃに作動油を供給した状態を示す。
【００４４】
この場合は、後側ピストン部材９と前側ピストン部材１３とが油圧力により後側ストッパ部材１０と前側ストッパ部材１４とにそれぞれ押し付けられる結果、前側ピストン部材１３が中間部材１６、後側ピストン部材９を介して押圧部材８を後側へ押圧し、該押圧部材８が押圧部８ｂでころがり軸受５の外輪を後側に押圧する。中間部材１６と押圧部材８及び固定スリーブ部材１２との間に隙間Δ1 ，Δ2 が生じ、ころがり軸受５，６の外輪スパンＬは最大となるので、油圧力を最大切削力よりも充分大きくすることで、切削力が主軸４に作用しても両ピストン部材９，１３が動くことはなく、定位置の重予圧となる（図６の予圧Ａ曲線）。
【００４５】
図２は、油圧回路１９の両電磁方向切換弁２８，２８を消磁して油圧室Ｒａ，Ｒｂをそれぞれ脱圧し、また油圧回路２０の電磁方向切換弁４０のソレノイドｂを励磁して予圧用前側油圧室Ｒｃに作動油を供給した状態を示す。
この場合は、後側ピストン部材９が後側ストッパ部材１０から離れて中間部材１６の後端部が上記隙間Δ 1 をつめて押圧部材８の内径側前端面に当接し得る状態となるので、前側ピストン部材１３が、前側ストッパ部材１４に押し付けられるまで移動することにより、中間部材１６を介して押圧部材８を強く後側へ押圧し、該押圧部材８が押圧部８ｂでころがり軸受５の外輪を後側に押圧する。外輪スパンＬが図１の状態よりもΔ1 だけ短い分、軸受予圧量が小さくなり、油圧力を最大切削スラスト力以上とすることで、定位置の中予圧となる（図６の予圧Ｂ曲線）。
【００４６】
図３は、油圧回路１９の分岐管３３ａの電磁方向切換弁２８のソレノイドを消磁して戻し用油圧室Ｒａを脱圧状態にするとともに、他の分岐管３３ｂの電磁方向切換弁２８のソレノイドを励磁して作動油を予圧用後側油圧室Ｒｂに供給し、また油圧回路２０の電磁方向切換弁４０のソレノイドａを励磁して予圧用前側油圧室Ｒｃを脱圧した状態を示す。
この時は、前側ピストン部材１３が前側ストッパ部材１４から離れて中間部材１６の前端部が上記隙間Δ 2 をつめて固定スリーブ１２の内径側後端面に当接し得る状態となるので、後側ピストン部材９が、後側ストッパ部材１０に押し付けられるまで移動することにより、中間部材１６を固定スリーブ部材１２に押し付ける。この結果、反力で押圧部材８が後側に動かされ、押圧部８ｂでころがり軸受５の外輪を後側に押圧する。外輪スパンＬが図２の状態よりもΔ2 −Δ1 （前述のように、Δ2 ＞Δ1 ）だけ短い分、軸受予圧量が小さくなり、油圧力を最大切削スラスト力以上とすることで、定位置の低予圧となる（図６の予圧Ｃ曲線）。
【００４７】
図４は、油圧回路１９の両電磁方向切換弁２８，２８を励磁して油圧室Ｒａ，Ｒｂに作動油を供給し、また油圧回路２０のソレノイドａを励磁して予圧用前側油圧室Ｒｃを脱圧した状態で示す。この場合は、油圧力を予圧ばね１７の力を含めてＰD （図６）に設定する。主軸４の回転数の上昇に伴って軸受内部の予圧がＰD よりも高くなると、後側ピストン部材９が、中間部材１６の後端部と押圧部材８の内径側前端面との間に前記隙間Δ１より小さい隙間Δ１’をあける位置まで前側に移動し、外輪スパンＬを短くして予圧の上昇を抑える（定圧予圧、図６の予圧Ｄ曲線）。
【００４８】
上記において、両油圧室Ｒａ，Ｒｂに供給される作動油の圧力が同一であっても、前に述べたように、戻し用油圧室Ｒａの受圧面積Ａ１よりも予圧用後側油圧室Ｒｂの受圧面積Ａ２が大きくなっているため、軸受予圧が高まる方向にころがり軸受５の外輪が変位する。
予圧Ｄ曲線は、軸受予圧上昇の上限を設定するリリーフ形と言えるもので、軸受予圧が設定値ＰＤに達するまでは定位置予圧の状態保つ。
【００４９】
また上記において、制御装置から指令を電空レギュレータ２７に与えて空気圧を設定する。エアオイルブースタ２６は、リリーフ弁の機能を持つため、流量が極めて少ない場合でも圧力制御が可能になる。ノンリーク形切換弁３０で油管路３４，３５を閉じると、作動油の非圧縮性により可動スリーブ部材７と後側ピストン部材９が固定される。これにより、工具交換時に主軸４に逆スラスト力が作用しても、主軸４の変位を防ぐことができる。
【００５０】
図６の予圧Ｅ曲線は、主軸４の回転数と設定予圧のテーブルに従い電空レギュレータ２７に指令を与えて空気圧を変え、主軸４の回転上昇に伴って油圧力、軸受予圧の上限を徐々に下げたものである。高速回転で高い予圧を維持すると、軸受寿命が低下するが、予圧Ｅ曲線の設定によって寿命を延ばすことができる。
【００５１】
また、従来、１ｍｍ以上であった主軸４の最大移動量（Δ１＋Δ２）を０．０５〜０．３ｍｍにすることが可能で、このように設定すると、定圧予圧時の設定油圧力（予圧の上限値）よりも大きな逆スラスト力が主軸４に加わった場合でも、ころがり軸受へのダメージを回避できる。
電磁比例流量制御弁２９は、通常、油圧室Ｒａ，Ｒｂへの作動油の供給時には全開状態とし、供給終了後は、適宜に絞って作動油の流動抵抗を大きくする。この結果、作動油の供給時間が短くなって素早い予圧切換えが可能になり、また、切削力の変動に起因する主軸４の変位が減衰されるようになる。
【００５２】
予圧を下げたり解除したりする場合は、必要があれば、予圧用の両油圧室Ｒｂ，Ｒｃを脱圧状態にして、戻し用油圧室Ｒａに作動油を供給し、可動スリーブ部材７を前側に変位させる。
なお、上記の予圧操作は基本的なもので、これ以外の方法でも予圧を付加することが可能である。
【００５３】
結局、図の主軸装置は次の長所を有する。
（ａ）主軸剛性を高めることのできる定位置予圧量を３段階まで設定することができる。
（ｂ）高速回転が可能な定圧予圧において、低速回転時に定位置予圧の要素を付加させたリリーフ予圧方式を取ったことで予圧設定が高く主軸剛性を高めることができる。もちろん通常の定圧予圧にも設定できる。
【００５４】
（ｃ）定圧予圧時の予圧量を連続的に可変にでき、ころがり軸受５に対して中速回転域での高剛性化と高速回転域での長寿命化を図れる。
（ｄ）可変量をΔ１とΔ２で小さく規制するため、大きな逆スラスト力が作用しても主軸４が振れ回ったりガタついたりしない。
（ｅ）油圧回路９に設けた電磁比例流量制御弁２９により、作動油の非圧縮性を利用して振動を減衰させることができる。
【００５５】
（ｆ）油圧回路１９にノンリーク形切換弁３０が設けられ、工具交換時に主軸４に逆スラスト力が作用しても、閉じた系内での作動油の非圧縮性により、主軸４が前側に大きく飛び出ることがない。
（ｇ）常に予圧ばね１７が作用しているため、定位置予圧設定における停止や低回転での予圧抜けを生じることはない。
（ｈ）予圧を下げる時に、可動スリーブ部材７の外周に設けられたＯリングの抵抗を考慮して戻し用油圧室Ｒａに油圧を与えることにより、可動スリーブ部材７を予圧減少方向に確実に変位させることができる。
【００５６】
図５の油圧回路１９は、空気管路３３を２つに分岐し、空圧源２５と電空レギュレータ２７を２つの系に共用させた構造となっているが、空気管路３３を分岐しない単独構造とすることも、また空気管路３３を３つに分岐してその三系統に空圧源２５と電空レギュレータ２７を共用させることもできる。前者の単独構造の場合は、１〜３個の油圧回路１９を油通路３ａ，３ｂ，３ｃの任意の１以上に接続することができる。この場合、油圧回路１９に接続されないで残された油通路には、油圧回路２０を接続する。後者の場合は、すべての油通路３ａ，３ｂ，３ｃに油圧回路１９の油管路を接続することは言うまでもない。空気管路３３を複数に分岐した油圧回路１９において、空圧源２５のみを全系統に共用させ、電空レギュレータ２７は各系に設けたり、或いは一部の系のみに共用されるなどの構成とすることができる。上記のすべてにおいて、油圧回路１９，２０の一方又は両方を、例えば、ノンリーク形切換弁３０を省くなど、種々変更することができる。
【００５７】
また、油圧室Ｒａ，Ｒｂ，Ｒｃの受圧面積Ａ１，Ａ２，Ａ３の大小関係と、隙間Δ１，Δ２の大小関係は、図のものに限らず任意であり、油圧回路１９，２０の構成や油圧室Ｒａ，Ｒｂ，Ｒｃに対する接続構成等によってこれらも種々変更される。なお、作動油が非圧縮性があるといっても完全ではないため、ノンリーク形切換弁３０や電磁比例流量制御弁２９は油圧室の近傍に設置し、伸縮性のない配管部品で接合する必要がある。
油圧回路１９は、図１の主軸装置以外の、例えば、図９や図１１等の主軸装置にも使用することができる。
【００６１】
【発明の効果】
以上説明したように、請求項１記載の発明によれば、定圧予圧と３段の定位置予圧が得られ、主軸の回転速度等に幅広く適合して予圧を付加することができる。
【００６２】
請求項１記載の主軸装置において、戻し用油圧室の受圧面積よりも予圧用後側油圧室の受圧面積を大きくすると、戻し用油圧室と予圧用後側油圧室に同圧の作動油を供給して予圧を高めることができるので、油圧回路の構成を簡単にしてコストを下げることができる。
また、請求項２又は３記載の主軸装置において、後側ピストン部材が後側ストッパ部材と中間部材とに当接するとともに、前側ピストン部材が前側ストッパ部材と中間部材とに当接した状態における、押圧部材と中間部材との間の隙間よりも固定スリーブ部材と中間部材との間の隙間を大きくすると、戻し用油圧室と予圧用前側油圧室を脱圧状態にして予圧用後側油圧室に作動油を供給した場合、前側ころがり軸受と後側ころがり軸受の外輪スパンが最小となるため、３段目の最も低い定位置予圧が得られる。
【００６３】
また、請求項１ないし３のいずれか１つに記載の主軸装置において、油圧室に作動油を供給してピストン部材でころがり軸受の外輪を押圧する軸受予圧用油圧回路が、空圧源と、該空圧源の空気圧を油圧に変換して作動油をノンリーク形切換弁が設けられた油管路を通じて油圧室に供給するエアオイルブースタと、上記空圧源に上記エアオイルブースタを連絡した空気管路に設けられ、空圧源によるエアオイルブースタの加圧と脱圧を切り換える電磁方向切換弁とを具備し、又は戻し用油圧室と予圧用後側油圧室に作動油を供給してピストン部材でころがり軸受の外輪を押圧する軸受予圧用油圧回路を、空圧源と、該空圧源の空気圧を油圧に変換して作動油をノンリーク形切換弁が設けられた油管路を通じて油圧室に供給するエアオイルブースタと、上記空圧源に上記エアオイルブースタを連絡した空気管路に設けられ、空圧源によるエアオイルブースタの加圧と脱圧を切り換える電磁方向切換弁とを具備した油圧回路とし、予圧用前側油圧室に作動油を供給する油圧回路を、油圧源の油管路に減圧弁と電磁方向切換弁を設けた油圧回路とした場合は、自体の機能に、エアオイルブースタにより油圧力を精度よく確実に調整して作動状態に適合した予圧を付加することができ、エアオイルブースタが持つ空気のクッション作用を有効に活用して予圧をより良好なものとすることができるといった軸受予圧用油圧回路の機能を相乗的に組み合わせることができる、高性能な主軸装置を得ることができる。また、ンリーク形切換弁で油管路を閉じることにより、例えば、工具交換時の主軸の前側変位を抑えてガタつきを防止することができる。
【００６４】
請求項６記載の発明によれば、油圧室内の作動油の非圧縮性を利用して、例えば、可動スリーブ部材や後側ピストン部材を固定し、逆スラスト力による主軸の前側変位を防ぐことができるようになる。
【図面の簡単な説明】
【図１】本発明に係る主軸装置の実施の形態を示す断面図である。
【図２】図１の主軸装置において、戻し用油圧室と予圧用後側油圧室を脱圧し、予圧用前側油圧室に作動油を供給した状態を示す主要部の断面図である。
【図３】図１の主軸装置において、戻し用油圧室と予圧用前側油圧室を脱圧し、予圧用後側油圧室に作動油を供給した状態を示す主要部の断面図である。
【図４】図１の主軸装置において、戻し用油圧室と予圧用後側油圧室に作動油を供給し、予圧用前側油圧室を脱圧にした状態を示す主要部の断面図である。
【図５】本発明に係る軸受予圧用油圧回路の実施の形態を示す図である。
【図６】図１の主軸装置の回転数と予圧の関係を示す図である。
【図７】従来の主軸装置の主要部の断面図である。
【図８】図７の主軸装置の回転数と予圧の関係を示す図である。
【図９】従来の他の主軸装置の主要部の断面図である。
【図１０】図９の主軸装置の回転数と予圧の関係を示す図である。
【図１１】従来の別の主軸装置の主要部の断面図である。
【図１２】図１１の主軸装置の回転数と予圧の関係を示す図である。
【符号の説明】
１主軸装置３ハウジング
３ａ，３ｂ，３ｃ油通路４主軸
５ころがり軸受７可動スリーブ部材
８押圧部材９後側ピストン部材
１０後側ストッパ部材１２固定スリーブ部材
１３前側ピストン部材１４前側ストッパ部材
１６中間部材１７予圧ばね
１９，２０油圧回路２５空圧源
２６エアオイルブースタ２６ａ空圧シリンダ
２６ｂ油圧シリンダ２７電空レギュレータ
２８，４０電磁方向切換弁２９電磁比例流量制御弁
３０ノンリーク形切換弁３１圧力センサ
３３空気管路３３ａ，３３ｂ分岐管
３４，３５，３８油管路３７油圧源
３９減圧弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bearing preload hydraulic circuit and a main shaft device for preloading a rolling bearing such as a main shaft of a machine tool and a preloading method for the rolling bearing.
[0002]
[Prior art]
As shown in FIG. 7, in a spindle device of a machine tool in which a main shaft 62 is rotatably supported by two sets of front and rear rolling bearings 63 and 64 in a tandem arrangement in a housing 61, the outer ring of the rolling bearings 63 and 64 is generally used. In the meantime, a spacer 65 is incorporated by applying a preload to them.
[0003]
Although this preloading method is simple, as shown in Fig. 8, the bearing preload rapidly rises at high speed rotation and seizure occurs (preload A curve). The preload B curve of the preload PB, which is not given and the preload is loosened when assembled, must be taken. For this reason, there is no main shaft rigidity at the time of low-speed rotation, and cutting ability will be inferior.
[0004]
Therefore, in Japanese Utility Model Publication No. 4-53457 and Japanese Patent No. 2528236, the following spindle device is proposed.
[0005]
(Actual Publication No. 4-53457)
As shown in FIG. 9, this main shaft device is a main shaft device in which a main shaft 62 is rotatably supported by two sets of front and rear rolling bearings 63 and 64 in a housing 61, and is fitted to an outer ring of the rolling bearing 63. The movable sleeve member 66 is inserted into the rear end portion of the housing 61 so as to be movable in the axial direction of the main shaft 62, and is inserted into the hydraulic chamber Rr formed in the housing 61 so as to be movable in the axial direction. A piston member 68 that applies a preload to the outer ring of the rolling bearing 63 by moving the movable sleeve member 66 to the rear side (right side in FIG. 9) via the member 67, and a rolling bearing by biasing the movable sleeve member 66 to the rear side. A preload spring 69 that applies preload to the outer ring 63 and a return spring 70 that pushes the piston member 68 back through the interposition member 67 are provided. As shown in FIG. The hydraulic oil is supplied from the hydraulic chamber Rr (not shown) and the movable sleeve member 66 is pushed rearward by the piston member 68 and the preload spring 69 to perform the fixed position preload. The movable sleeve member 66 can be pushed to perform constant pressure preload.
[0006]
(Japanese Patent No. 2528236)
As shown in FIG. 11, this spindle device is a spindle device in which a main shaft 62 is rotatably supported in a housing 61 by two sets of front and rear rolling bearings 63 (the front rolling bearings are not shown). The movable sleeve member 66 fitted to the outer ring of the rolling bearing 63 and fitted in the rear end portion of the housing 61 so as to be movable in the axial direction of the main shaft 62, and movable in the axial direction into the hydraulic chambers Rs and Rt. Is attached to the housing 61, the piston member 68 that preloads the outer ring of the rolling bearing 63 by moving the movable sleeve member 66 to the rear side (right side in FIG. 11), and the movable sleeve member 66 and the piston member 68. And an adjustment member 72 that restricts the amount of movement of the motor, and as shown in FIG. 12, the fixed position preload is switched to three stages, and the preload at a low speed can be increased so as to be within the seizure limit. You have me.
Reference numeral 73 denotes a hydraulic circuit that supplies hydraulic oil to the hydraulic chambers Rs and Rt, and mainly includes a hydraulic pump 74.
[0007]
In FIG. 12, δ1 is an initial gap (total of initial gaps) of the rolling bearing 63, δ2 is a gap formed between the adjustment member 72 and the movable sleeve member 66, and δ3 is a gap between the adjustment member 72 and the piston member 68. It is a gap formed in
[0008]
[Problems to be solved by the invention]
However, the above spindle device has the following problems.
(Actual Publication No. 4-53457)
(A) When the main shaft 62 is pulled with a force larger than the spring force of the preload spring 69 during the constant pressure preload at the high speed rotation setting, the main shaft 62 moves and swings to damage the rolling bearing.
[0009]
(B) The constant pressure preload cannot be set larger than the fixed position preload. The cutting ability is reduced at the time of constant pressure preload with a small spring force.
(C) In the case of a spindle device having a structure in which the push rod is pushed forward from the rear part of the spindle 62 to release the tool, the spindle 62 comes out forward when the push rod is operated.
(D) Only two stages of high speed (constant pressure preload) and low speed (constant position preload) can be switched.
[0010]
(Japanese Patent No. 2528236)
(E) Since the entire area is in a fixed position preload system, the higher the rotation speed, the higher the preload setting “preload C curve” on the high speed rotation side.
(F) If a rotation command is given at the high-speed rotation setting, the preload is released at the low-speed rotation, so that the ball of the rolling bearing 63 slips during acceleration / deceleration to generate heat, and the rotation is rattling. Arise.
[0011]
(G) On the high-speed rotation side, the main shaft 62 is rattled due to preload loss at the time of stopping, and the runout accuracy is not good.
(H) Even if an operation for decreasing the preload is performed after increasing the preload, the O-ring of the movable sleeve member 66 becomes a resistance and the movement is poor.
(I) The greater the number of preload switching stages, the longer the installation space is required.
[0012]
Also, any of the main spindle devices has a structure in which the hydraulic oil is supplied to the hydraulic chamber by the hydraulic pump 74 (FIG. 11). However, the oil flow rate is very small, and the hydraulic pressure adjustment valve does not allow the oil flow. If the pressure does not occur to some extent, it is difficult for the pressure to change. Therefore, several pressure regulating valves are set and switched to control the pressure, and cannot be made continuously variable.
[0013]
The present invention has been made in view of the above., mainShaftPlacementAndIn its spindle deviceAn object is to provide a rational rolling bearing preloading method.
[0019]
[Means for Solving the Problems]
To achieve the above objective,Claim1In the main shaft device in which the main shaft is rotatably supported by the rolling bearing in the housing, the invention described is fitted to the outer ring of the rolling bearing and forms a return hydraulic chamber to form the main shaft in the housing. A movable sleeve member that is movably inserted in a direction, a preload rear hydraulic chamber, a pressing member that is integrally fixed to the front end of the movable sleeve member, and a shaft in the preload rear hydraulic chamber A rear piston member that preloads the outer ring of the rolling bearing by moving the pressing member rearward and fixed to the front end of the pressing member; A fixed sleeve member having a rear stopper member for preventing movement to the front side and a pre-pressure front hydraulic chamber, and being integrally fixed to the housing with the pre-load front hydraulic chamber facing the pre-load rear hydraulic chamber When, A front piston member, which is inserted into the pre-pressure front hydraulic chamber so as to be movable in the axial direction, and a rear end portion of the fixed sleeve member facing the rear stopper member, and a rear side of the front piston member A front stopper member that prevents movement to the rear, an intermediate member that is axially movable between the rear piston member and the front piston member, and between the pressing member and the fixed sleeve member, and the rear The side stopper member and the front stopper member are provided with preload springs that are urged to increase the distance between them.
[0020]
In this means, when the return hydraulic chamber is brought into a depressurized state and hydraulic fluid is supplied from the hydraulic circuit to the preload rear hydraulic chamber and the preload front hydraulic chamber, the rear piston member and the front piston member are moved rearward by the hydraulic pressure. The side stopper member and the front side stopper member are pressed strongly against each other, and the movable sleeve member and the fixed sleeve member are stretched through the intermediate member. By making the oil pressure sufficiently larger than the maximum cutting thrust force, both piston members do not move even when the cutting force acts on the main shaft, and a performance equivalent to a heavy preload at a fixed position can be obtained.
[0021]
In addition, when the return hydraulic chamber and the preload rear hydraulic chamber are brought into a depressurized state, hydraulic oil is supplied to the front piston member and an oil pressure higher than the maximum cutting thrust force is applied to the front piston member, the front piston The member strongly presses the pressing member via the intermediate member and is pressed against the front stopper member, thereby applying a preload to the rolling bearing. In this case, the intermediate member abuts against the pressing member to eliminate the gap therebetween, and the outer ring span of the tandem rolling bearing is shortened by the gap, resulting in a medium preload at a fixed position.
[0022]
In addition, if the return hydraulic chamber and the preload front hydraulic chamber are in a depressurized state and hydraulic oil is supplied to the rear piston member and hydraulic pressure greater than the maximum cutting thrust force is applied to the rear piston member, The side piston member presses the intermediate member against the fixed sleeve member and is pressed against the rear stopper member, and moves the pressing member toward the movable sleeve member to apply a preload at a fixed position to the rolling bearing.
In addition, when the preload front hydraulic chamber is in a depressurized state and hydraulic fluid is supplied from the hydraulic circuit to the return hydraulic chamber and the preload rear hydraulic chamber, the hydraulic pressure and the spring force of the preload spring become the preload of the rolling bearing. work. In this case, it becomes a constant pressure preload.
[0023]
The “front side” of the front piston member or the like is usually the tip side of the spindle on which the tool is mounted, and the “rear side” is the opposite side, but it is not absolute and varies depending on the viewing direction. The reverse of the above can also be interpreted.
[0024]
In the above spindle device, the pressure receiving area of the preload rear hydraulic chamber can be made larger than the pressure receiving area of the return hydraulic chamber.2).
In this configuration, when hydraulic oil of the same pressure is supplied to the return hydraulic chamber and the preload rear hydraulic chamber, a force corresponding to the pressure receiving area difference between the return hydraulic chamber and the preload rear hydraulic chamber works to apply the preload. Increase. Therefore, the hydraulic circuit for the return hydraulic chamber and the preload rear hydraulic chamber can be made the same.
[0025]
In addition, the rear piston member is in contact with the rear stopper member and the intermediate member, and the gap between the pressing member and the intermediate member in a state in which the front piston member is in contact with the front stopper member and the intermediate member. The gap between the fixed sleeve member and the intermediate member can be increased.3).
In this configuration, when the return hydraulic chamber and the preload front hydraulic chamber are in a depressurized state and hydraulic fluid is supplied to the preload rear hydraulic chamber, the intermediate member contacts the fixed sleeve member with no gap, and is arranged in tandem. The outer ring span of the rolling bearing is smaller than the outer ring span when hydraulic fluid is supplied to the preload front hydraulic chamber with the return hydraulic chamber and the preload rear hydraulic chamber in the depressurized state. Fixed position preload.
[0026]
Claims1Or3In the spindle device according to any one of the above, hydraulic oil is supplied to the hydraulic chamberFor bearing preload that presses the outer ring of the rolling bearing with the piston memberHydraulic circuitBut,An air pressure source, an air oil booster that converts the air pressure of the air pressure source into hydraulic pressure, and supplies hydraulic oil to a hydraulic chamber through an oil line provided with a non-leak type switching valve; and the air oil booster And an electromagnetic directional switching valve that switches between pressurization and depressurization of the air oil booster by an air pressure source.(Claims)4).
In this configuration,When the electromagnetic directional control valve is in a pressurized state, the air oil booster is operated by the air pressure of the pneumatic pressure source, and the hydraulic oil is supplied to the hydraulic chamber. When the electromagnetic direction switching valve is switched to the depressurization, the hydraulic chamber is depressurized by the depressurization of the air oil booster. The air oil booster converts the air pressure given from the air source into oil pressure (usually increased pressure) due to the difference between the air pressure receiving area and the hydraulic oil pressure area. (0.005 to 1.5 cc), the pressure can be adjusted with certainty, enabling continuous and continuous pressure adjustment, and when the pressure in the hydraulic chamber rises abnormally, it rises by air cushioning Absorb pressure. like thisHydraulic circuit for bearing preloadMachineClaims making use of the ability1Or3A preload is applied to the rolling bearing of the spindle device according to any one of the above.By closing the oil pipeline with a non-leak type switching valve and fixing, for example, a movable sleeve member, it is possible to suppress rattling by suppressing displacement of the main shaft during tool replacement.
[0027]
Claims1Or3In the spindle device according to any one of the above, hydraulic oil is supplied to the return hydraulic chamber and the preload rear hydraulic chamberFor bearing preload that presses the outer ring of the rolling bearing with the piston memberHydraulic circuit,An air pressure source, an air oil booster that converts the air pressure of the air pressure source into hydraulic pressure, and supplies hydraulic oil to a hydraulic chamber through an oil line provided with a non-leak type switching valve; and the air oil booster And an electromagnetic directional switching valve that switches between pressurization and depressurization of the air oil booster by an air pressure source.A hydraulic circuit that supplies hydraulic oil to the preload front hydraulic chamber can be a hydraulic circuit in which a pressure reducing valve and an electromagnetic directional switching valve are provided in an oil pipeline of a hydraulic power source.5).
In this configuration,UpSupply hydraulic oil from the bearing preload hydraulic circuit to the return hydraulic chamber and the preload rear hydraulic chamber, and supply hydraulic oil from another hydraulic circuit having a hydraulic source to the preload front hydraulic chamber. Term1Or3A preload is applied to the rolling bearing of the spindle device described in any of the above.By closing the oil pipeline with a non-leak type switching valve and fixing, for example, a movable sleeve member, it is possible to suppress rattling by suppressing displacement of the main shaft during tool replacement.
[0028]
Claim6The invention described in claim 4Or 5DescribedA preloading method for rolling bearings in a spindle device.Then, after supplying the hydraulic oil from the air oil booster to the hydraulic chamber through the oil pipe, the non-leak type switching valve is closed to perform the fixed position preload.
With this means, for example, the movable sleeve member and the rear piston member can be fixed by the incompressibility of the hydraulic oil in the hydraulic chamber.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the accompanying drawings.
1 to 6 show an embodiment of the present invention, and reference numeral 1 denotes a spindle device. The spindle device 1 includes a housing 3, a spindle 4, rolling bearings 5 and 6, a movable sleeve member 7, a pressing member 8, a rear piston member 9, a rear stopper member 10, and a fixed sleeve member 12. The front piston member 13, the front stopper member 14, the intermediate member 16, the preload spring 17, and the motor 18 are provided, and the preload can be applied to the rolling bearing by the hydraulic circuits 19 and 20 (FIG. 5). It is like that.
[0030]
The housing 3 has oil passages 3a, 3b, 3c. The main shaft 4 is supported in the housing 3 so as to be rotatable in the circumferential direction by two sets of rolling bearings 5 and 6 arranged in tandem. The movable sleeve member 7 has a cylindrical shape and is fitted to the outer ring of a pair of rolling bearings 5 on the rear side (right side in FIG. 1) and forms an annular return hydraulic chamber Ra in the housing 3. The main shaft 4 is inserted so as to be movable in the axial direction. The return hydraulic chamber Ra is in direct communication with the oil passage 3 a of the housing 3. The movable sleeve member 7 is formed with an oil passage 7 a communicating with the oil passage 3 b of the housing 3.
[0031]
The pressing member 8 has an annular shape and is integrally fixed to the front end portion of the movable sleeve member 7 with a large number of bolts 11a (only one is shown in FIG. 1). The pressing member 8 presses an annular preloading rear hydraulic chamber Rb, an oil passage 8a communicating the preloading rear hydraulic chamber Rb with an oil passage 7a of the movable sleeve member 7, and an outer ring of the rolling bearing 5. And a pressing portion 8b to be provided. An annular rear piston member 9 is liquid-tightly inserted in the preload rear hydraulic chamber Rb so as to be movable in the axial direction of the main shaft 4. Also, the pressing member8A rear stopper member 10 is integrally fixed to the front end of the rear piston member 9 by a large number of bolts 11b (in this case, only one is shown in FIG. 1) to prevent the rear piston member 9 from moving forward. doing.
[0032]
The fixed sleeve member 12 is formed in a cylindrical shape, is fitted to the outer ring of the pair of front roller bearings 6 and is fixed to the housing 3 integrally. The fixed sleeve member 12 is provided with an annular preload front hydraulic chamber Rc and an oil passage 12 a that communicates the preload front hydraulic chamber Rc with the oil passage 3 c of the housing 3. In the preload front hydraulic chamber Rc, an annular front piston member 13 is also fluid-tightly inserted so as to be movable in the axial direction of the main shaft 4. A front stopper member 14 faces the rear stopper member 10 at the rear end of the fixed sleeve member 12 and is fixed integrally with a number of bolts 11c (only one is shown in FIG. 1). The movement of the front piston member 13 to the rear side is prevented.
[0033]
The intermediate member 16 is formed in an annular shape, and is guided by both stopper members 10 and 14 between the rear piston member 9 and the front piston member 13 and between the pressing member 8 and the fixed sleeve member 12. It is provided so as to be movable in the direction. Further, the preload spring 17 is provided between the rear stopper member 10 and the front stopper member 14 so as to be biased so as to increase the distance therebetween. For the preload spring 17, a coil spring, a leaf spring or the like is used concentrically with the main shaft 4 or arranged at a predetermined angular interval.
[0034]
The pressure receiving area A2 of the preload rear hydraulic chamber Rb is set larger than the pressure receiving area A1 of the return hydraulic chamber Ra, and the rear piston member 9 contacts the rear stopper member 10 and the intermediate member 16, respectively. And the front piston member 13 is in contact with the front stopper member 14 and the intermediate member 16, respectively.InPress member 8The front end surface on the inner diameter side of the rear hydraulic chamber Rb for preload inAnd intermediate member 16Rear end faceBetweenIs formed in the fixed sleeve member 12, and the clearance Δ between the inner diameter side rear end surface of the preload front hydraulic chamber Rc and the front end surface of the intermediate member 16 is fixed. 2 Can be opened, the aboveThan gap Δ1the aboveThe gap Δ2 is set large.
[0035]
The motor 18 rotates the main shaft 4, and is provided between the rolling bearing 5 and the bearing 21 in the housing 3 by inserting the main shaft 4 into the rotor sleeve of the rotor 18 b rotated by the stator 18 a. Reference numeral 22 denotes a pressing member integrally fixed to the front end surface of the fixed sleeve member 12, and 23 denotes a ball guide that improves the movement of the movable sleeve member 7.
[0036]
The hydraulic circuit 19 supplies hydraulic oil to the return hydraulic chamber Ra and the preload rear hydraulic chamber Rb, and includes an air pressure source 25, an air oil booster 26, an electropneumatic regulator (electromagnetic pneumatic regulator). 27, a pair of electromagnetic direction switching valves 28, a pair of electromagnetic proportional flow control valves 29, a pair of non-leak type switching valves (electromagnetic switching valves) 30, and a pair of pressure sensors 31.
[0037]
The air pressure source 25 includes a compressor or the like. The air oil booster 26 is formed by integrally connecting a hydraulic cylinder 26b having a small pressure area to a pneumatic cylinder 26a having a large pressure receiving area, and converts a given air pressure into a hydraulic pressure by a difference between the pressure receiving area and the pressure area. The air pressure cylinder 26 a is connected to the air source 25 through an air pipe 33 to increase the pressure. The electropneumatic regulator 27 adjusts the air pressure in accordance with a voltage-type or current-type external command from a control device (not shown) such as an NC device, and is provided in the air line 33.
[0038]
The electromagnetic direction switching valve 28 connects the air pipe 33 to the bottom side air chamber of the pneumatic cylinder 26a in an excited state, and opens the rod side air chamber of the pneumatic cylinder 26a to the atmosphere to operate the air oil booster 26. In addition, the air duct 33 is connected to the rod-side air chamber of the pneumatic cylinder 26a in a demagnetized state, and the bottom-side air chamber is opened to the atmosphere so that the air oil booster 26 is in a depressurized state. The pipes 33 are provided in the branch pipes 33a and 33b, respectively.
[0039]
Each electromagnetic proportional flow control valve 29, each non-leak type switching valve 30, and each pressure sensor 31 are connected to the oil pipes 34 and 35 connected to the hydraulic cylinder 26b of the air oil booster 26 in the above order from the upstream side to the downstream side. Are provided respectively. Each non-leak type switching valve 30 opens and closes the oil pipelines 34 and 35, respectively. The output signal of the pressure sensor 31 is input to the control device and used for feedback control of the electropneumatic regulator 27. The oil conduit 34 is connected to the oil passage 3 a of the housing 3, and the other oil conduit 35 is connected to the oil passage 3 b of the housing 3.
[0040]
The hydraulic circuit 20 supplies hydraulic oil to the preload front hydraulic chamber Rc, and includes a pressure reducing valve 39 and an electromagnetic direction switching valve 40 in an oil pipe line 38 of a hydraulic source 37 such as a hydraulic pump. The oil conduit 38 is connected to the oil passage 3 c of the housing 3.
[0041]
The pressure reducing valve 39 is preset with a hydraulic pressure acting on the pressure receiving area A3 of the hydraulic chamber Rc. This set pressure is a pressure that can sufficiently withstand the reverse thrust force on the main shaft 4 (the force in the direction in which the main shaft 4 is pulled forward). For example,
Allowable reverse thrust force Fa = 10000N
Then
Oil pressure P1 = (Fa / A3) × 1.5-2
A3 = 50cm²
Then
P1 = 300 to 400 N / cm²(3-4Mpa)
It becomes.
Generally, since the hydraulic pressure source 37 is 5 MPa or more, the pressure is reduced by the pressure reducing valve 39. Since the amount of hydraulic fluid flowing into the hydraulic chamber Rc is small and the pressure follow-up is poor even if it is variable, the set pressure of the pressure reducing valve 39 is usually fixed to one type.
[0042]
When the solenoid a is energized, the electromagnetic direction switching valve 40 closes the hydraulic pressure source 37 side of the oil conduit 38 and connects the oil passage 3c side to the oil tank 41 to bring the preload front hydraulic chamber Rc into a depressurized state. When the solenoid b is energized (solenoid a is demagnetized), the oil line 38 is opened to supply hydraulic oil to the preload front hydraulic chamber Rc, and the oil line is at a neutral position where both solenoids a and b are demagnetized. 38 is closed.
[0043]
Next, the operation of the spindle apparatus configured as described above will be described.
In FIG. 1, the solenoid of the electromagnetic direction switching valve 28 of the branch pipe 33a of the hydraulic circuit 19 is demagnetized to depressurize the return hydraulic chamber Ra, and the solenoid of the electromagnetic direction switching valve 28 of the other branch pipe 33b is excited. The hydraulic oil is supplied to the preload rear hydraulic chamber Rb, and the solenoid b of the electromagnetic direction switching valve 40 of the hydraulic circuit 20 is excited to supply the hydraulic oil to the preload front hydraulic chamber Rc.
[0044]
In this case, as a result of the rear piston member 9 and the front piston member 13 being pressed against the rear stopper member 10 and the front stopper member 14 by the hydraulic pressure,The front piston member 13 presses the pressing member 8 to the rear side through the intermediate member 16 and the rear piston member 9,The pressing member 8 presses the outer ring of the rolling bearing 5 to the rear side at the pressing portion 8b. Since the gaps Δ1 and Δ2 are generated between the intermediate member 16 and the pressing member 8 and the fixed sleeve member 12, and the outer ring span L of the rolling bearings 5 and 6 is maximized, the oil pressure should be sufficiently larger than the maximum cutting force. Thus, even if a cutting force is applied to the main shaft 4, the piston members 9 and 13 do not move, resulting in a heavy preload at a fixed position (preload A curve in FIG. 6).
[0045]
FIG. 2 shows a preloading front side by demagnetizing both electromagnetic direction switching valves 28 and 28 of the hydraulic circuit 19 to depressurize the hydraulic chambers Ra and Rb and exciting a solenoid b of the electromagnetic direction switching valve 40 of the hydraulic circuit 20. The state which supplied hydraulic oil to the hydraulic chamber Rc is shown.
in this case,The rear piston member 9 is separated from the rear stopper member 10 and the rear end portion of the intermediate member 16 has the gap Δ. 1 So that it can be brought into contact with the inner diameter side front end surface of the pressing member 8,The front piston member 13 isBy moving until pressed against the front stopper member 14,Through the intermediate member 16TheStrongly press member 8To the backPress andThe pressing member 8 presses the outer ring of the rolling bearing 5 rearward at the pressing portion 8b.The bearing preload is reduced by the amount of Δ1 shorter than the outer ring span L in the state shown in FIG. 1, and the oil pressure is set to the maximum cutting thrust force or more to achieve a medium preload at a fixed position (preload B curve in FIG. 6). .
[0046]
FIG. 3 shows that the solenoid of the electromagnetic direction switching valve 28 of the branch pipe 33a of the hydraulic circuit 19 is demagnetized to bring the return hydraulic chamber Ra into a depressurized state, and the solenoid of the electromagnetic direction switching valve 28 of the other branch pipe 33b is turned off. The state is shown in which the hydraulic oil is excited and supplied to the preload rear hydraulic chamber Rb, and the solenoid a of the electromagnetic direction switching valve 40 of the hydraulic circuit 20 is excited to depressurize the preload front hydraulic chamber Rc.
At this timeThe front piston member 13 is separated from the front stopper member 14, and the front end portion of the intermediate member 16 is in the gap Δ. 2 So that it can be brought into contact with the inner diameter side rear end surface of the fixing sleeve 12,The rear piston member 9 isBy moving until pressed against the rear stopper member 10,Press the intermediate member 16 against the fixed sleeve member 12Kick. As a result, the pressing member 8 is moved rearward by the reaction force.The outer ring of the rolling bearing 5 is pressed rearward by the pressing portion 8b.By reducing the outer ring span L by Δ2−Δ1 (Δ2> Δ1 as described above) compared to the state shown in FIG. 2, the bearing preload is reduced, and the oil pressure is set to the maximum cutting thrust force or more. Low preload (preload C curve in FIG. 6).
[0047]
FIG. 4 illustrates the excitation of both electromagnetic direction switching valves 28 and 28 of the hydraulic circuit 19 to supply hydraulic oil to the hydraulic chambers Ra and Rb, and the excitation of the solenoid a of the hydraulic circuit 20 to set the preload front hydraulic chamber Rc. Shown in depressurized state. In this case, the oil pressure including the force of the preload spring 17 is set to PD (FIG. 6). When the preload inside the bearing becomes higher than PD as the rotational speed of the main shaft 4 increases, the rear piston member 9And a position where a gap Δ1 ′ smaller than the gap Δ1 is formed between the rear end portion of the intermediate member 16 and the inner diameter side front end surface of the pressing member 8.Move forward,The outer ring span L is shortened to suppress an increase in preload (constant pressure preload, preload D curve in FIG. 6).
[0048]
In the above, even if the pressure of the hydraulic oil supplied to both the hydraulic chambers Ra and Rb is the same, as described above, the preload rear hydraulic chamber Rb is more than the pressure receiving area A1 of the return hydraulic chamber Ra. Since the pressure receiving area A2 is large, the outer ring of the rolling bearing 5 is displaced in the direction in which the bearing preload increases.
The preload D curve can be said to be a relief type that sets the upper limit of the bearing preload increase, and keeps the fixed position preload state until the bearing preload reaches the set value PD.
[0049]
In the above description, a command is given from the control device to the electropneumatic regulator 27 to set the air pressure. Since the air oil booster 26 has a relief valve function, pressure control is possible even when the flow rate is extremely small. When the oil pipelines 34 and 35 are closed by the non-leak type switching valve 30, the movable sleeve member 7 and the rear piston member 9 are fixed due to the incompressibility of the hydraulic oil. Thereby, even if a reverse thrust force acts on the main shaft 4 at the time of tool change, the displacement of the main shaft 4 can be prevented.
[0050]
The preload E curve in FIG. 6 gives a command to the electropneumatic regulator 27 in accordance with the rotation speed of the main shaft 4 and the set preload table to change the air pressure, and gradually increases the upper limit of the oil pressure and the bearing preload as the main shaft 4 rotates. It has been lowered. If a high preload is maintained at high speed, the bearing life is reduced, but the life can be extended by setting a preload E curve.
[0051]
In addition, the maximum movement amount (Δ1 + Δ2) of the spindle 4 which has been 1 mm or more in the past can be set to 0.05 to 0.3 mm, and when set in this way, the set oil pressure (preload pressure) at the constant pressure preload is set. Even when a reverse thrust force larger than the upper limit value is applied to the main shaft 4, damage to the rolling bearing can be avoided.
The electromagnetic proportional flow control valve 29 is normally fully opened when hydraulic oil is supplied to the hydraulic chambers Ra and Rb, and after the supply is completed, the flow resistance of the hydraulic oil is increased by appropriately restricting. As a result, the hydraulic oil supply time is shortened to enable quick preload switching, and the displacement of the main shaft 4 due to fluctuations in the cutting force is attenuated.
[0052]
When lowering or releasing the preload, if necessary, both the preload hydraulic chambers Rb and Rc are depressurized, the hydraulic oil is supplied to the return hydraulic chamber Ra, and the movable sleeve member 7 is moved to the front side. Displace to.
Note that the above preload operation is basic, and it is possible to apply preload by other methods.
[0053]
After all, the spindle device of the figure has the following advantages.
(A) A fixed position preload amount capable of increasing the spindle rigidity can be set up to three stages.
(B) In the constant pressure preload capable of high speed rotation, the preload setting is high and the spindle rigidity can be increased by adopting the relief preload system in which the element of the fixed position preload is added at the time of low speed rotation. Of course, it can also be set to normal constant pressure preload.
[0054]
(C) The amount of preload at the time of constant pressure preload can be made continuously variable, so that the rolling bearing 5 can have high rigidity in the medium speed rotation region and long life in the high speed rotation region.
(D) Since the variable amount is restricted to be small by Δ1 and Δ2, the main shaft 4 does not swing or rattle even when a large reverse thrust force is applied.
(E) The electromagnetic proportional flow control valve 29 provided in the hydraulic circuit 9 can attenuate the vibration by utilizing the incompressibility of the hydraulic oil.
[0055]
(F) The non-leak type switching valve 30 is provided in the hydraulic circuit 19, and the main shaft 4 is moved forward due to the incompressibility of the hydraulic oil in the closed system even if a reverse thrust force is applied to the main shaft 4 when changing the tool. There is no big jump out.
(G) Since the preload spring 17 is always acting, there is no stop in the fixed position preload setting and no preload loss at low rotation occurs.
(H) When lowering the preload, the movable sleeve member 7 is reliably displaced in the direction of decreasing the preload by applying hydraulic pressure to the return hydraulic chamber Ra in consideration of the resistance of the O-ring provided on the outer periphery of the movable sleeve member 7. Can be made.
[0056]
The hydraulic circuit 19 of FIG. 5 has a structure in which the air line 33 is branched into two and the pneumatic source 25 and the electropneumatic regulator 27 are shared by the two systems, but the air line 33 is not branched. The air source 33 can be divided into three, and the air pressure source 25 and the electropneumatic regulator 27 can be shared by the three systems. In the former single structure, 1 to 3 hydraulic circuits 19 can be connected to any one or more of the oil passages 3a, 3b, 3c. In this case, the hydraulic circuit 20 is connected to the remaining oil passage without being connected to the hydraulic circuit 19. In the latter case, it goes without saying that the oil pipelines of the hydraulic circuit 19 are connected to all the oil passages 3a, 3b, 3c. In the hydraulic circuit 19 in which the air pipe 33 is branched into a plurality of parts, only the pneumatic pressure source 25 is shared by all systems, and the electropneumatic regulator 27 is provided in each system, or is shared only by some systems. It can be. In all of the above, one or both of the hydraulic circuits 19, 20 can be variously modified, for example, omitting the non-leak type switching valve 30.
[0057]
The magnitude relationship between the pressure receiving areas A1, A2, and A3 of the hydraulic chambers Ra, Rb, and Rc and the magnitude relationship between the gaps Δ1 and Δ2 are not limited to those shown in the figure, and the configuration of the hydraulic circuits 19 and 20 and the hydraulic pressure These are variously changed depending on the connection configuration to the chambers Ra, Rb, and Rc. In addition, since it is not perfect that the hydraulic oil is incompressible, the non-leak type switching valve 30 and the electromagnetic proportional flow control valve 29 should be installed in the vicinity of the hydraulic chamber and joined with non-stretchable piping parts. There is.
The hydraulic circuit 19 can be used for a spindle apparatus other than the spindle apparatus of FIG. 1, for example, the spindle apparatus of FIGS.
[0061]
【The invention's effect】
As explained above, the claims1According to the described invention, a constant pressure preload and a three-stage fixed position preload can be obtained, and the preload can be applied in accordance with a wide range of rotation speeds of the main shaft and the like.
[0062]
Claim1If the pressure receiving area of the preload rear hydraulic chamber is larger than the pressure receiving area of the return hydraulic chamber, the hydraulic oil of the same pressure is supplied to the return hydraulic chamber and the preload rear hydraulic chamber to perform preload. Therefore, it is possible to simplify the configuration of the hydraulic circuit and reduce the cost.
Claims2Or3In the spindle apparatus described above, the rear piston member is in contact with the rear stopper member and the intermediate member, and the front piston member is in contact with the front stopper member and the intermediate member. If the clearance between the fixed sleeve member and the intermediate member is made larger than the clearance, the hydraulic chamber for return and the front hydraulic chamber for preload are in a depressurized state, and hydraulic fluid is supplied to the rear hydraulic chamber for preload. Since the outer ring span of the rolling bearing and the rear rolling bearing is minimized, the lowest fixed position preload in the third stage is obtained.
[0063]
Claims1Or3In the spindle device according to any one of the above, hydraulic oil is supplied to the hydraulic chamberFor bearing preload that presses the outer ring of the rolling bearing with the piston memberThe hydraulic circuitAn air pressure source, an air oil booster that converts the air pressure of the air pressure source into hydraulic pressure, and supplies hydraulic oil to the hydraulic chamber through an oil line provided with a non-leak type switching valve; and the air oil booster connected to the air pressure source And an electromagnetic directional switching valve that switches between pressurization and depressurization of the air oil booster by an air pressure source.Or supply hydraulic oil to the return hydraulic chamber and the preload rear hydraulic chamberBearing preloading that presses the outer ring of the rolling bearing with a piston memberHydraulic circuit,An air pressure source, an air oil booster that converts the air pressure of the air pressure source into hydraulic pressure, and supplies hydraulic oil to a hydraulic chamber through an oil line provided with a non-leak type switching valve; and the air oil booster And an electromagnetic directional switching valve that switches between pressurization and depressurization of the air oil booster by an air pressure source.If the hydraulic circuit that supplies hydraulic oil to the pre-load front hydraulic chamber is a hydraulic circuit with a pressure reducing valve and an electromagnetic directional switching valve in the oil source oil line,The oil pressure can be adjusted accurately and reliably with the air oil booster to add preload suitable for the operating condition, and the air cushion action of the air oil booster can be used effectively to improve the preload. CanA high-performance spindle device that can synergistically combine the functions of the bearing preload hydraulic circuit can be obtained.Further, by closing the oil pipeline with the leak-type switching valve, for example, the front side displacement of the main shaft at the time of tool change can be suppressed and rattling can be prevented.
[0064]
Claim6According to the described invention, by utilizing the incompressibility of the hydraulic oil in the hydraulic chamber, for example, the movable sleeve member and the rear piston member are fixed, so that the front side displacement of the main shaft due to the reverse thrust force can be prevented. Become.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a spindle device according to the present invention.
2 is a cross-sectional view of the main part showing a state in which the return hydraulic chamber and the preload rear hydraulic chamber are depressurized and the working oil is supplied to the preload front hydraulic chamber in the spindle apparatus of FIG. 1;
3 is a cross-sectional view of the main part showing a state in which the return hydraulic chamber and the preload front hydraulic chamber are decompressed and hydraulic oil is supplied to the preload rear hydraulic chamber in the spindle device of FIG. 1. FIG.
4 is a cross-sectional view of the main part showing a state in which hydraulic oil is supplied to the return hydraulic chamber and the preload rear hydraulic chamber and the preload front hydraulic chamber is depressurized in the spindle apparatus of FIG. 1; FIG.
FIG. 5 is a diagram showing an embodiment of a bearing preload hydraulic circuit according to the present invention.
6 is a diagram showing the relationship between the rotational speed and the preload of the spindle device of FIG. 1. FIG.
FIG. 7 is a cross-sectional view of a main part of a conventional spindle device.
8 is a diagram showing the relationship between the rotational speed and the preload of the spindle device of FIG.
FIG. 9 is a cross-sectional view of a main part of another conventional spindle device.
10 is a diagram showing the relationship between the rotational speed and the preload of the spindle device of FIG. 9;
FIG. 11 is a cross-sectional view of a main part of another conventional spindle device.
12 is a diagram showing the relationship between the rotational speed of the spindle device of FIG. 11 and preload.
[Explanation of symbols]
1 Spindle device 3 Housing
3a, 3b, 3c Oil passage 4 Spindle
5 Rolling bearing 7 Movable sleeve member
8 Pressing member 9 Rear piston member
10 Rear stopper member 12 Fixed sleeve member
13 Front piston member 14 Front stopper member
16 Intermediate member 17 Preload spring
19, 20 Hydraulic circuit 25 Air pressure source
26 Air oil booster 26a Pneumatic cylinder
26b Hydraulic cylinder 27 Electropneumatic regulator
28, 40 Electromagnetic directional control valve 29 Proportional flow control valve
30 Non-leak switching valve 31 Pressure sensor
33 Air duct 33a, 33b Branch pipe
34, 35, 38 Oil pipeline 37 Hydraulic source
39 Pressure reducing valve

Claims

ハウジング内に、主軸が、ころがり軸受で回転自在に支持された主軸装置において、
上記ころがり軸受の外輪に嵌着されるとともに戻し用油圧室を形成して上記ハウジングに主軸の軸方向に移動自在に嵌挿された可動スリーブ部材と、
予圧用後側油圧室を有し、上記可動スリーブ部材の前端部に一体に固定された押圧部材と、
上記予圧用後側油圧室内に軸方向に移動自在に装入され、上記押圧部材を後側に移動させて上記ころがり軸受の外輪に予圧をかける後側ピストン部材と、
上記押圧部材の前端部に固定され、上記後側ピストン部材の前側への移動を阻止する後側ストッパ部材と、
予圧用前側油圧室を有し、該予圧用前側油圧室を上記予圧用後側油圧室に向き合わせてハウジングに一体に固定された固定スリーブ部材と、
上記予圧用前側油圧室内に軸方向に移動自在に装入された前側ピストン部材と、
上記固定スリーブ部材の後端部に上記後側ストッパ部材に向き合わせて設けられ、上記前側ピストン部材の後側への移動を阻止する前側ストッパ部材と、
上記後側ピストン部材と前側ピストン部材との間及び上記押圧部材と固定スリーブ部材との間に軸方向に移動自在に設けられた中間部材と、
上記後側ストッパ部材と前側ストッパ部材の部分にそれらの間隔が大きくなるように付勢して設けられた予圧ばねとを具備したことを特徴とする主軸装置。In the spindle device in which the spindle is rotatably supported by a rolling bearing in the housing,
A movable sleeve member that is fitted to the outer ring of the rolling bearing and that forms a return hydraulic chamber and is fitted to the housing so as to be movable in the axial direction of the main shaft;
A pressing member that has a pre-loading rear hydraulic chamber and is integrally fixed to the front end of the movable sleeve member;
A rear piston member that is inserted in the preload rear hydraulic chamber so as to be axially movable, moves the pressing member to the rear side, and applies a preload to the outer ring of the rolling bearing;
A rear stopper member fixed to the front end portion of the pressing member and preventing the rear piston member from moving forward;
A fixed sleeve member that has a preload front hydraulic chamber, and is fixed to the housing integrally with the preload front hydraulic chamber facing the preload rear hydraulic chamber;
A front piston member inserted in the preload front hydraulic chamber movably in the axial direction;
A front stopper member provided at a rear end portion of the fixed sleeve member so as to face the rear stopper member, and preventing movement of the front piston member to the rear side;
An intermediate member provided between the rear piston member and the front piston member and between the pressing member and the fixed sleeve member so as to be axially movable;
A main spindle device comprising: a preload spring provided by energizing the rear stopper member and the front stopper member so as to increase the distance therebetween.

戻し用油圧室の受圧面積よりも予圧用後側油圧室の受圧面積が大きくされたことを特徴とする請求項１記載の主軸装置。Hydraulic chambers spindle device according to claim 1, wherein the pressure receiving area of the preload for rear hydraulic chamber is greater than the pressure receiving area for the return.

後側ピストン部材が後側ストッパ部材と中間部材とに当接するとともに、前側ピストン部材が前側ストッパ部材と中間部材とに当接した状態における、押圧部材と中間部材との間の隙間よりも固定スリーブ部材と中間部材との間の隙間が大きくされたことを特徴とする請求項１又は２記載の主軸装置。When the rear piston member is in contact with the rear stopper member and the intermediate member, and the front piston member is in contact with the front stopper member and the intermediate member, the fixed sleeve is larger than the gap between the pressing member and the intermediate member. 3. The spindle apparatus according to claim 1, wherein a gap between the member and the intermediate member is increased.

請求項１ないし３のいずれか１つに記載の主軸装置において、
油圧室に作動油を供給してピストン部材でころがり軸受の外輪を押圧する軸受予圧用油圧回路が、空圧源と、該空圧源の空気圧を油圧に変換して作動油をノンリーク形切換弁が設けられた油管路を通じて油圧室に供給するエアオイルブースタと、上記空圧源に上記エアオイルブースタを連絡した空気管路に設けられ、空圧源によるエアオイルブースタの加圧と脱圧を切り換える電磁方向切換弁とを具備したことを特徴とする主軸装置。The spindle device according to any one of claims 1 to 3 ,
Hydraulic circuit bearing preload for pressing the outer ring of the rolling bearing in the piston member by supplying hydraulic oil to the hydraulic chamber, air pressure source and, nonleak type switching valve the hydraulic oil by converting the air pressure of the air pressure source to the hydraulic The air oil booster that supplies the hydraulic chamber through the oil pipe provided with the air pressure booster and the air pressure line that connects the air oil booster to the air pressure source and pressurizes and depressurizes the air oil booster by the air pressure source. A spindle device comprising an electromagnetic directional switching valve for switching .

請求項１ないし３のいずれか１つに記載の主軸装置において、
戻し用油圧室と予圧用後側油圧室に作動油を供給してピストン部材でころがり軸受の外輪を押圧する軸受予圧用油圧回路が、空圧源と、該空圧源の空気圧を油圧に変換して作動油をノンリーク形切換弁が設けられた油管路を通じて油圧室に供給するエアオイルブースタと、上記空圧源に上記エアオイルブースタを連絡した空気管路に設けられ、空圧源によるエアオイルブースタの加圧と脱圧を切り換える電磁方向切換弁とを具備した油圧回路とされ、
予圧用前側油圧室に作動油を供給する油圧回路が、油圧源の油管路に減圧弁と電磁方向切換弁が設けられた油圧回路とされたことを特徴とする主軸装置。The spindle device according to any one of claims 1 to 3 ,
A bearing preload hydraulic circuit that supplies hydraulic oil to the return hydraulic chamber and the preload rear hydraulic chamber and presses the outer ring of the rolling bearing with a piston member converts the air pressure source and the air pressure of the air pressure source into oil pressure Air oil booster that supplies hydraulic oil to the hydraulic chamber through an oil line provided with a non-leak switching valve, and an air line that connects the air oil booster to the air pressure source. A hydraulic circuit having an electromagnetic directional switching valve that switches between pressurization and depressurization of the oil booster ;
A main shaft device characterized in that a hydraulic circuit for supplying hydraulic oil to a preload front hydraulic chamber is a hydraulic circuit in which a pressure reducing valve and an electromagnetic direction switching valve are provided in an oil line of a hydraulic source.

請求項４又は５記載の主軸装置におけるころがり軸受の予圧方法であって、エアオイルブースタから作動油を油管路を通じて油圧室に供給した後、ノンリーク形切換弁を閉じて定位置予圧を行うことを特徴とするころがり軸受の予圧方法。 6. A method for preloading a rolling bearing in a spindle device according to claim 4 or 5, wherein after supplying the hydraulic oil from the air oil booster to the hydraulic chamber through the oil line, the non-leak type switching valve is closed to perform the fixed position preload. A pre-loading method for a rolling bearing.