JP3635501B2

JP3635501B2 - Optical element grinding method and apparatus

Info

Publication number: JP3635501B2
Application number: JP25877394A
Authority: JP
Inventors: 俊哉秋田
Original assignee: Olympus Corp
Current assignee: Olympus Corp
Priority date: 1994-09-27
Filing date: 1994-09-27
Publication date: 2005-04-06
Anticipated expiration: 2020-04-06
Also published as: JPH0890403A

Description

【０００１】
【産業上の利用分野】
本発明は、ガラス、セラミックスなどの高脆材料を球面形状に加工する手段に係わり、詳しくは光学素子の研削方法とその装置に関する。
【０００２】
【従来の技術】
従来、光学素材を研削加工により、カップ型ホイールを用いて、粗研削から仕上げ研削までを一貫して単一加工機上で行う手段としては、特開平４−２２３８５９号公報所載の技術が開示されている。
【０００３】
図１１は上記従来技術における研削装置の主要部を示す。１０１は第１環状砥石、１０２は第２環状研削砥石を示し、図示を省略した回転駆動軸に同心に取り付けられている。第２環状砥石１０２は、加工初期状態において第１環状砥石１０１の砥石先端部１０１ａよりもスペーサ１０４により前方へ突出した状態で取り付けられている。また、第２環状研削砥石１０２はネジ１０３を介して回転駆動軸の軸方向に移動可能な構造となっている。また、第２環状研削砥石１０２は粗研削用砥石、第１環状研削砥石１０１は仕上げ研削用砥石として構成されている。
【０００４】
上記構成における研削加工は、回転駆動軸を回転させながら、第１環状研削砥石１０１または第２環状研削砥石１０２を被加工物に当接しながら行う。第２環状研削砥石１０２による粗研削加工が完了したのち、図示を省略した工具をカニメ穴１０５に挿入して第２環状研削砥石を取り外し、第１環状研削砥石１０１により、仕上げ研削加工が行われる。なお、この従来技術には、第２環状研削砥石をシリンダー機構により軸方向に出没させて、粗研削加工と仕上げ研削加工との切り換えを行う技術も開示されている。
【０００５】
【発明が解決しようとする課題】
上記従来技術においては、粗研削加工が完了した後、加工を一時中断して、環状研削砥石を取り外す操作を行う必要があること、また、環状研削砥石を軸方向に出没させるシリンダー機構が複雑で、所定の球面形状を得るために微調整が必要であることなどにより、その操作に時間が掛かり、加工能率が低下するという問題点がある。
【０００６】
また、仕上げ研削ではできるだけ高メッシュの砥粒工具を用いたほうが高精度な仕上げ面を得ることができるが、工具の目つぶれが発生し易く、加工面精度が悪化する。この影響を少なくするために、高メッシュ砥粒工具に対しては、バネ圧やエア圧によるラッピング加工を適用する。従って、従来技術のように、粗研削工程も仕上げ加工工程も同様な加工手段を用いて、精度の高い加工を高能率に安定して行うことは困難であるという問題点があった。
【０００７】
本発明は、上記従来の問題点に鑑みてなされたもので、請求項１または２に係る発明の目的は、粗研削から仕上げ研削までを一貫して高能率で、高精度に安定して加工ができる光学素子の研削方法を提供することである。
請求項３、４、５、または６に係る発明の目的は、粗研削から仕上げ研削までを一貫して高能率で、高精度に安定して加工ができる光学素子の研削装置を提供することである。
【０００８】
【課題を解決するための手段】
上記課題を解決するために、請求項１または２に係る発明は、工具軸の回転中心に対して同心に配設された複数の研削工具によって球面形状にワークを研削する光学素子の研削方法において、前記複数の研削工具は、円盤型研削工具と総型研削工具とからなり、円盤型研削工具は工具軸の外周に、総型研削工具は工具軸の端面に配設し、ワークを強制回転させながら円盤型研削工具をワークの端面から接近させて粗研削した後、工具軸を回動した後、総型研削工具上にワークを押圧して従属回転させながら仕上げ研削することを特徴とする。
【０００９】
請求項３または４に係る発明は、工具軸の回転中心に対して同心に配設された複数の研削工具によって球面形状にワークを研削する光学素子の研削装置において、前記複数の研削工具は、カップ型研削工具と総型研削工具とからなり、総型研削工具はカップ型研削工具の内側に配され、互いに相対的に出没できるように工具軸に沿って進退自在に嵌装され、ワーク軸は、その軸方向に進退自在であり、ワークを着脱自在にしかつ強制回転させるチャック機構とワークを開放してワーク軸方向に押圧する押圧機構とを備え、前記工具軸はその軸心と前記ワーク軸の軸心とにその交点にて直交する軸を中心として回動する回動機構を備えて構成したことを特徴とする。
請求項５または６に係る発明は、工具軸の回転中心に対して同心に配設された複数の研削工具によって球面形状にワークを研削する光学素子の研削装置において、前記複数の研削工具は、円盤型研削工具と総型研削工具とからなり、円盤型研削工具は工具軸の外周に、総型研削工具は工具軸の端面に配設し、ワーク軸は、その軸方向に進退自在であり、ワークを着脱自在にしかつ強制回転させるチャック機構とワークを開放してワーク軸方向に押圧する押圧機構とを備え、前記工具軸はその軸心と前記ワーク軸の軸心とにその交点にて直交する軸を中心として回動する回動機構を備えて構成したことを特徴とする。
【００１０】
【作用】
請求項１または２に係る発明の作用では、円盤型研削工具による粗研削が終了すると、工具軸を回動させ、総型研削工具により仕上げ研削を直ちに行うので、一貫した作業が連続して行える。また、総型研削工具の上に、ワークを押圧して従属回転させながら仕上げ研削を行うので、面精度のよい仕上げ面となる。
請求項２に係る発明の作用では、上記作用に加え、総型研削工具を球心揺動させながら仕上げ研削を行うので、より高精度の仕上面となる。
【００１１】
請求項３または４に係る発明の作用では、総型研削工具はカップ型研削工具の内側に配され、互いに相対的に出没できるように工具軸に沿って進退自在に嵌装され、かつ、工具軸はその軸心と前記ワーク軸の軸心とにその交点にて直交する軸を中心として回動する回動機構を備えて構成しているので、粗研削時には、カップ型研削工具と回動機構とによる相対運動によりワークに球面を創成し、仕上げ研削時には、総型研削工具をカップ型研削工具から突出させてカップ型研削工具への干渉を回避し、回動機構により総型研削工具に揺動運動を与える。また、ワーク軸はその軸方向に進退自在であり、ワークを着脱自在にしかつ強制回転させるチャック機構とワークを開放してワーク軸方向に押圧する押圧機構とを備えているので、粗研削時には、チャック機構によりワークを把持して強制回転させ、かつ軸方向に送りを与え、仕上げ研削時には、チャックを開放してワークを総型研削工具の上に押圧する。
請求項４に係る発明では、上記作用に加え、総型研削工具の曲率半径がワークの仕上げ曲率半径と一致しているので、高精度に球面を仕上げる。
【００１２】
請求項５または６に係る発明の作用では、円板型研削工具は工具軸の外周に、総型研削工具は工具軸の端面に配設し、かつ、工具軸はその軸心と前記ワーク軸の軸心とその交点にて直交する軸を中心として回動する回動機構を備えているので、粗研削時には、円盤型研削工具の外周面によりワークに球面を整形し、仕上げ研削時には、回動機構により工具軸を回動させてから、総型研削工具に揺動運動を与える。またワーク軸はその軸方向に進退自在であり、ワークを着脱自在にしかつ強制回転させるチャック機構とワークを開放してワーク軸方向に押圧する押圧機構とを備えているので、粗研削時には、チャック機構によりワークを把持して強制回転させ、かつ軸方向に送りを与え、仕上げ研削時には、チャックを開放してワークを総型研削工具の上に押圧する。
請求項６に係る発明の作用では、上記作用に加え、円盤型研削工具の縦断面曲率半径は、ワークの仕上げ曲率半径より仕上げ代分加減してなり、前記総型研削工具の曲率半径は、ワ−クの仕上げ曲率半径と一致しているので、粗研削時には正確な仕上げ代が残り、仕上げ研削時には高精度に球面を仕上げる。
【００１３】
【実施例１】
図１〜図５は第１実施例を示し、図１は粗研削時の研削装置の正面断面図、図２は仕上げ研削時の研削装置の正面断面図、図３は研削装置の工具軸の横断面図、図４は総型研削工具を進退させる出没機構の配管系統図、図５は変形例の総型研削工具を進退させる出没機構の配管系統図である。
【００１４】
本実施例の光学素子の研削装置を説明する。図１において、研削装置は大別してワーク軸１と工具軸７とからなる。工具軸７は、円筒形の工具軸本体８の一端にカップ型研削工具２３をネジ部８ｃにて工具軸７の軸心Ｂと同心に螺着し、そのゆるみ防止のためにナット２１がカップ型研削工具２３に嵌着されている。また、カップ型研削工具２３の内周にはフランジ２に貼付された総型研削工具１１が嵌装されている。フランジ２の外周には、ストッパー９が配設され、フランジ２を進退自在に保持する。ストッパー９は中継ぎ２０の一端に固着されている。中継ぎ２０は工具軸本体８の中心部に嵌装され、そのもう一方の端部はネジ部８ｄにて工具軸本体８に螺着され、ゆるみ防止のためにナット２２が中継ぎ２０に嵌着されている。
【００１５】
総型研削工具１１およびフランジ２は、ストッパー９をガイドとして軸心Ｂ方向に対して進退自在に構成されている。その範囲は、フランジ２の底面２ｂと中継ぎ２０とが接触し、カップ型研削工具２３が突出して総型研削工具１１が埋没する位置（図１）から、フランジ２の突起部２ａとストッパー９の突起部９ａとが接触し、総型研削工具１１が突出してカップ型研削工具２３が埋没する位置（図２）までである。工具軸７には、エアー（圧縮空気）を流体とする総型研削工具１１の進退移動のための出没機構（図４）が図示を省略したロータリージョイントを介して連結されている。図４に示すように、この出没機構はコンプレッサー５１と、真空ポンプ５２と、それぞれの電磁弁５３、５４とから構成されている。フランジ２とストッパー９は互いに気密的に嵌合しているので、エアーは電磁弁５３が開かれたとき、コンプレッサー５１から工具軸７の中継ぎ２０の孔２０ａに送られ、フランジ２の底面２ｂを押圧して総型研削工具１１を突出させる。また電磁弁５３が閉じられ、電磁弁５４が開かれたとき、エアーは真空ポンプにより吸引され、総型研削工具１１は埋没する。
【００１６】
工具軸本体８は図示を省略した駆動源装置と連結され、軸心Ｂを中心に回転駆動自在な構成となっている。また、工具軸本体８が回転すると、カップ型研削工具２３が回転する。さらに、図３に示すように、ストッパー９のキー部９ｂとフランジ２の溝部２ｃとが嵌め合うことにより、工具軸本体８の回転方向に対して相対移動がないようになっている。そのため、工具軸本体８の回転は、ストッパー９、フランジ２を介して総型研削工具１１に伝達されるように構成されている。さらに、工具軸本体８は、ワーク軸１の軸心Ａと工具軸７の軸心Ｂとにその交点にて直交する軸を支点Ｏ₀として回動する図示を省略した回動機構により、旋回運動および球心揺動（α方向）ができるようになっている。
【００１７】
カップ型研削工具２３および総型研削工具１１は、ダイヤモンド粉末、ＣＢＮ、アルミナ、炭化珪素、酸化セリウム、ジルコニアなどの砥粒をメタルボンド、レジンボンド、メタルレジンボンドまたはビトリファイドボンドなどで結合したものである。カップ型研削工具２３の加工面２３ａは凸面で、曲率半径Ｒ₁はワーク３の仕上げ曲率半径Ｒ₀より仕上げ代分小さく形成され、曲率中心Ｏ₁が工具軸７の回動機構の支点Ｏ₀と合致するように工具軸本体８のネジ部８ｃにより設定されている。さらに、総型研削工具１１の加工面１１ａは凸面で、仕上げ曲率半径Ｒ₀に等しいＲ₂に設定されている。
【００１８】
図１において、ワーク軸１は、ワーク軸本体５と、その端部に設けられたコレットチャック４と、ワーク軸本体５の中心部に設けられたカンザシ６とにより構成される。ワーク軸本体５は軸心Ａを中心として回転自在に、かつ、矢印Ｃ方向に移動自在に構成されている。ワーク３は円板状のガラス素材であり、最終的には図３の破線で示す凹球面３ｂに仕上げられる。ワーク３の上面は皿１２に貼付されており、皿１２の上面中央部には凹部が形成され、凹部には棒状でその先端が球形のカンザシ６が嵌合し得るようになっている。カンザシ６の上端は、ワーク軸本体に取り付けられた加圧装置（図示省略）に接続されている。さらに、ワーク３および皿１２の外周面には、ワーク軸本体５に取り付けられたコレットチャック４の先端部があり、ワーク３の外周面の把持および開放を行うようになっている。
【００１９】
ワーク３とカップ型研削工具２３および総型研削工具１１との加工時の接触部には、図示を省略したクーラント供給装置に連結されたノズル１０よりクーラントが供給されるように構成されている。
【００２０】
本実施例の研削装置を用いた研削方法について説明する。図１は粗研削加工の状況を示している。ワーク軸１では、皿１２に貼付されたワーク３をコレットチャック４により把持する。工具軸７では、総型研削工具１１を埋没させ、カップ型研削工具２３を突出させておく。工具軸７およびワーク軸１を回転させる。ノズル１０よりクーラントを供給し、工具軸７をα方向に旋回（少なくともカップ型研削工具２３の加工面２３ａがワーク３の中心３ａに達するまで）させることにより、ワ−ク３の外周から球面を創成する粗研削加工を行う。
【００２１】
なお、カップ型研削工具２３の加工面２３ａにおける曲率半径Ｒ₁の中心Ｏ₁が、工具軸７の回動機構の支点Ｏ₀と一致するように、カップ型研削工具２３の高さ調整を行う。その調整はナット２１をゆるめ、カップ型研削工具２３を回して、工具軸本体８のネジ部８ｃでの軸心Ｂ方向への移動により行う。それ故、ワーク３はカップ型研削工具２３の加工面２３ａの曲率半径Ｒ₁に合致した凹球面３ｂ（図１の破線で示す面）を得る。
【００２２】
また、総型研削工具１１は、その出没機構（図４）により、フランジ２および総型研削工具１１を吸引し、フランジ２の底面２ｂが中継ぎ２０に接触する位置まで後退させてある。それ故、カップ型研削工具２３が突出しているので、総型研削工具１１とワーク３とが接触することはない。
【００２３】
図２は仕上げ研削の状況を示す。ワーク軸１を上方（Ｃ方向）に移動させた後、工具軸７をθ₁（ワーク軸の軸心Ａから総型研削工具１１による球心揺動の中央までの角度）に傾斜させる。総型研削工具１１の出没機構（図４）により、フランジ２および総型研削工具１１を前進させ、ストッパー９の突起部９ａにフランジ２の突起部２ａが接触する位置で空気圧により保持する。この状態で、総型研削工具１１はカップ型研削工具２３より突出している。
【００２４】
つぎに、コレットチャック４を開放し、カンザシ６を加圧装置（図示省略）により押し出し、ワーク３を総型研削工具１１の加工面１１ａに押圧する。ノズル１０よりクーラントを供給させ、工具軸７を回動機構の支点Ｏ₀を中心として球心揺動させることによりワーク３の仕上げ研削を行う。このとき、粗研削後のワーク３の凹球面３ｂの曲率半径Ｒ₁は総型研削工具１１の加工面１１ａの曲率半径Ｒ₂（＝Ｒ₀）より仕上げ代分だけ小さいので、仕上げ研削の初期にはワーク３と総型研削工具１１との接触は外当り（ワーク３の外周部分から当たる）になる。それ故、ワーク３は総型研削工具１１の回転により連れ回り（従属回転）が良好となる。
【００２５】
なお、予め総型研削工具１１の加工面１１ａにおける曲率半径Ｒ₂の中心Ｏ₂が工具軸７の球心揺動（α）の支点Ｏ₀と一致するように、総型研削工具１１の高さ調整を行う。その調整はナット２２をゆるめ、ストッパー９を回して、工具軸本体８のネジ部８ｄでの軸心Ｂ方向への移動により行う。
【００２６】
以上、本実施例によれば、高能率に粗研削から仕上げ研削までの加工を一貫して行うことができ、かつ総型研削工具の上にワークを押圧して従属回転させながら仕上げ研削を行うので、安定した仕上げ研削加工により高精度の光学素子を得ることができる。
【００２７】
本実施例の変形例について説明する。まず、図５に総型研削工具の出没装置の変形例を示す。コンプレッサー５５はコンバム５６のイン側５６ａに接続し、コンバム５６のアウト側５６ｃ、吸引側５６ｂが電磁弁５７、５８を介して中継ぎ２０の孔２０ａと接続している。電磁弁５７、５８の開閉によりフランジ２の底面２ｂを押し出しまたは吸引し、総型研削工具の出没を行う。この利点は装置が簡略になることである。
【００２８】
また、本実施例では、仕上げ研削するとき工具軸を球心揺動させてワークのラジアル方向に総型研削工具の加工面を摺動させているが、若干球面精度の点に差はあるものの、球心揺動は必ずしも必要ではなく、球心揺動をせずとも、ワークが従属回転するので、仕上げ研削を行うことができる。
さらに、本実施例では、カップ型研削工具を工具軸本体に固定し、総型研削工具を軸心方向に出没させる構成としたが、これに替えて、総型研削工具を工具軸本体に固定し、カップ型研削工具を出没させることもできる。その場合の研削装置は、カップ型研削工具を出没機構と連結する構造とする。
【００２９】
【実施例２】
図６〜図７は第２実施例を示し、図６は粗研削時の研削装置の正面断面図、図７は仕上げ研削時の正面断面図である。本実施例はワークを凹形状から凸形状に変更した点と総型研削工具の出没機構の構造とが第１実施例と異なる。その他は第１実施例と同様であり、同一の部材には同一の符号を付して説明を省略する。
【００３０】
図６において、フランジ２はシリンダー２４のピストン部２４ａとベアリング２５を介して回転自在かつ進退自在に連結されている。また、カップ型研削工具２３の加工面２３ａは凹面で、曲率半径Ｒ₁はワーク３の仕上げ曲率半径Ｒ₀より仕上げ代分大きく形成され、総型研削工具１１の加工面１１ａは凹面で、曲率半径Ｒ₂は仕上げ曲率半径Ｒ₀と同一に形成されている。その他の研削装置の構造は第１実施例と同様である。
【００３１】
本実施例の研削装置を用いた研削方法について説明する。図６は粗研削加工の状況を示している。ワーク軸１では、皿１２に貼付されたワーク３をコレットチャック４により把持する。工具軸７では、総型研削工具１１を埋没させ、カップ型研削工具２３を突出させておく。工具軸７およびワーク軸１を回転させる。ノズル１０よりクーラントを供給し、工具軸７をα方向に旋回（少なくともカップ型研削工具２３の加工面２３ａがワーク３の中心３ａに達するまで）させることにより、ワ−ク３の外周から球面を創成する粗研削加工を行う。
【００３３】
なお、カップ型研削工具２３の加工面２３ａにおける曲率半径Ｒ₁の中心Ｏ₁が、工具軸７の回動機構の支点Ｏ₀と一致するように、カップ型研削工具２３の高さ調整を行う。その調整はナット２１をゆるめ、カップ型研削工具２３を回して、工具軸本体８のネジ部８ｃでの軸心Ｂ方向への移動により行う。それ故、ワーク３はカップ型研削工具２３の加工面２３ａの曲率半径Ｒ₁に合致した凸球面３ｂ（図６の破線で示す面）を得る。
【００３４】
また、総型研削工具１１は、シリンダー２４により、フランジ２および総型研削工具１１を引き戻し、フランジ２の底面２ｂが中継ぎ２０に接触する位置まで後退させてある。それ故、カップ型研削工具２３が突出しているので、総型研削工具１１とワーク３とが接触することはない。
【００３５】
図７は仕上げ研削の状況を示す。ワーク軸１を上方（Ｃ方向）に移動させた後、工具軸７をθ₁（ワーク軸の軸心Ａから総型研削工具１１による球心揺動の中央までの角度）に傾斜させる。総型研削工具１１に連結したシリンダー２４により、フランジ２および総型研削工具１１を前進させ、ストッパー９の突起部９ａにフランジ２の突起部２ａが接触する位置で空気圧により保持する。この状態で、総型研削工具１１はカップ型研削工具２３より突出している。
【００３６】
つぎに、コレットチャック４を開放し、カンザシ６を加圧装置（図示省略）により押し出し、ワーク３を総型研削工具１１の加工面１１ａに押圧する。ノズル１０よりクーラントを供給させ、工具軸７を回動機構の支点Ｏ₀を中心として球心揺動させることによりワーク３の仕上げ研削を行う。このとき、粗研削後のワーク３の凸球面３ｂの曲率半径Ｒ₁は総型研削工具１１の加工面１１ａの曲率半径Ｒ₂（＝Ｒ₀）より仕上げ代分だけ大きいので、仕上げ研削の初期にはワーク３と総型研削工具１１との接触は外当り（ワーク３の外周部分から当たる）になる。それ故、ワーク３は総型研削工具１１の回転により連れ回り（従属回転）が良好となる。
【００３７】
なお、予め総型研削工具１１の加工面１１ａにおける曲率半径Ｒ₂の中心Ｏ₂が工具軸７の球心揺動（α）の支点Ｏ₀と一致するように、総型研削工具１１の高さ調整を行う。その調整はナット２２をゆるめ、ストッパー９を回して、工具軸本体８のネジ部８ｄでの軸心Ｂ方向への移動により行う。
【００３８】
以上、本実施例によれば、凸形状のワークにおいても、高能率に粗研削から仕上げ研削までの加工を一貫して行うことができ、かつ総型研削工具の上にワークを押圧して従属回転させながら仕上げ研削を行うので、安定した仕上げ研削加工により高精度の光学素子を得ることができる。
【００３９】
つぎに、本実施例でも、カップ型研削工具を工具軸本体に固定し、総型研削工具を軸心方向に出没させる構成としたが、これに替えて、総型研削工具を工具軸本体に固定し、カップ型研削工具を出没させることもできる。その場合の研削装置は、カップ型研削工具をシリンダーと連結する構造とする。また本実施例ではシリンダーはエアー（圧縮空気）を用いているが、油圧シリンダーやエアーハイドロシリンダーを用いることもできる。
【００４０】
【実施例３】
図８〜図１０は第３実施例を示し、図８は粗研削時の研削装置の正面断面図、図９は仕上げ研削時の正面断面図、図１０は工具軸の変形例を示す半断面図である。本実施例は工具軸の構成のみに特徴があるので、ワーク軸の構成などは第１および第２実施例と同一であり、同一の部材には同一の符号を付し、説明を省略する。
【００４１】
図８において、工具軸本体８の外周面に、円盤型研削工具たるダイヤモンド砥粒の電着工具３１が、加工面３１ａの縦断面曲率半径Ｒ₁の中心Ｏ₁と工具軸７の回動機構の支点Ｏ₀とが一致するように装着されている。また、総型研削工具１１を貼付したフランジ２は、そのネジ部２ｃにて、工具軸本体８のネジ部８ｃに同軸に螺着され、ゆるみ止めにネジ部２ｃにナット３０が嵌着されている。総型研削工具１１の加工面１１ａの曲率半径Ｒ₂はワークの仕上げ曲率半径Ｒ₀と一致しており、ワーク３が凹形状なので、電着工具３１の縦断面曲率半径Ｒ₁はワークの仕上げ曲率半径Ｒ₀より仕上げ代の分だけ小さく形成されている。また電着工具３１の外径Ｄ_kは、図８のように幅Ｗがワーク３の外径より小さい場合には縦断面曲率半径Ｒ₁の丁度２倍に形成する。しかし、幅Ｗがワーク３の外径より大きい場合には、２倍未満にして電着工具３１の縦断面曲率半径Ｒ₁による球面整形を干渉しないようにしてもよい。
【００４２】
工具軸本体８は図示を省略した駆動源装置と連結され、軸心Ｂを中心に回転駆動自在な構成となっている。工具軸本体８の回転は、電着工具３１および総型研削工具１１伝達されるように構成されている。さらに、工具軸本体８は、ワーク軸１の軸心Ａと工具軸７の軸心Ｂとにその交点にて直交する軸を支点Ｏ₀として回動する図示を省略した回動機構により、回動および球心揺動（α方向）ができるようになっている。
【００４３】
本実施例の研削装置を用いた研削方法について説明する。図８は粗研削加工の状況を示している。ワーク軸１では、皿１２に貼付されたワーク３をコレットチャック４により把持する。工具軸７では、回動機構により工具軸７の軸心Ｂがワーク軸１の軸心Ａに対して垂直になるまで傾斜させておく。工具軸７およびワーク軸１を回転させる。ノズル１０よりクーラントを供給し、ワーク軸を下方（Ｃ方向）に送ることにより電着工具３１ワーク３を粗研削加工する。ワーク３の下面には、電着工具３１の回転とワーク軸１の強制回転とＣ方向への送りとにより、凹球面３ｂが形成される。
【００４４】
図９は仕上げ研削の状況を示す。ワーク軸１を上方（Ｃ方向）に移動させた後、工具軸７をθ₀（ワーク軸の軸心Ａから総型研削工具１１による球心揺動の中央までの角度）まで戻す。つぎに、コレットチャック４を開放し、カンザシ６を加圧装置（図示省略）により押し出し、ワーク３を総型研削工具１１の加工面１１ａに押圧する。ノズル１０よりクーラントを供給させ、工具軸７を回動機構の支点Ｏ₀を中心として球心揺動させることによりワーク３の仕上げ研削を行う。このとき、粗研削後のワーク３の凹球面３ｂの曲率半径Ｒ₁は仕上げ曲率半径Ｒ₂（＝Ｒ₀）より小さいので、仕上げ研削の初期にはワーク３と総型研削工具１１との接触は外当り（ワーク３の外周部分から当たる）になる。それ故、ワーク３は総型研削工具１１の回転により連れ回り（従属回転）が良好となる。
【００４５】
なお、予め、総型研削工具１１の加工面１１ａにおける曲率半径Ｒ₂の中心Ｏ₂が回動機構の支点Ｏ₀と合致するように、総型研削工具１１の高さ調整をおこなう。その調整はナット３０をゆるめ、フランジ２を回して、工具軸本体８のネジ部８ｅでの軸心Ｂ方向への移動により行う。
【００４６】
本実施例によれば、凹形状のワークにおいて、前記第１実施例と同様な効果を得るとともに、総型研削工具の出没機構が必要ないので、研削装置の構造を簡略にすることができる。
【００４７】
本実施例の変形例について説明する。まず、図１０は工具軸の変形例を示し、電着工具４１が工具軸７の軸心Ｂに対して、γの傾斜角で装着されている点に特徴がある。粗研削加工するときは、電着工具４１の傾斜角γまで工具軸７を傾けて回転させ、ワーク軸１を下方（Ｃ方向）に送ることにより行う。この場合、電着工具４１の加工面４１ａがワーク３に対して下方の端面より斜めに接触を始めるので、切込みが円滑に行われる。
【００４８】
つぎに、本実施例では、円盤型研削工具にダイヤモンド砥粒の電着工具を用いたが、総型研削工具と同様に、第１実施例で記述したＣＢＮなどの砥粒を結合した円盤型研削工具を用いてもよい。
また、本実施例では、凹形状のワ−クを研削する場合について説明したが、加工面の縦断面形状が凹面で幅がワークの外径より大きな円盤型研削工具と、凹面の加工面を有する総型研削工具とを用いれば、凸形状のワークを研削することができる。この場合、円盤型研削工具の加工面の縦断面曲率半径は、ワークの仕上げ曲率半径より仕上げ代の分だけ大きな曲率半径となる。
さらに、本実施例では、工具軸に球心揺動を与えて、総型研削工具により仕上げ研削をしているが、第１実施例と同様に、仕上がり面精度に若干の差はあるものの、球心揺動を必ずしも必要とせず、総型研削工具の上にワークを押圧して工具軸を回転させるのみでも、ワ−クが従属回転するので、仕上げ研削を行うことができる。
【００４９】
【発明の効果】
請求項１〜２に係る発明によれば、高能率に粗研削から仕上げ研削までの加工を一貫して行うことができ、かつ総型研削工具の上にワークを押圧して従属回転させながら仕上げ研削を行うので、安定した仕上げ研削加工により高精度の光学素子を得ることができるとともに、総型研削工具の出没機構の必要がないので、研削装置の構造を簡略にすることができる。請求項２に係る発明によれば、上記効果に加え、総型研削工具を球心揺動させながら仕上げ研削を行うので、より高精度の仕上面となる。請求項３〜４に係る発明によれば、高能率に粗研削から仕上げ研削までの加工を一貫して行うことができ、かつ総型研削工具の上にワークを押圧して従属回転させながら仕上げ研削を行う、安定した高精度の光学素子の研削装置を提供することができる。請求項５〜６に係る発明によれば、高能率に粗研削から仕上げ研削までの加工を一貫して行うことができ、かつ総型研削工具の上にワークを押圧して従属回転させながら仕上げ研削を行う、安定した高精度の光学素子の研削装置を提供することができるとともに、総型研削工具の出没機構の必要がないので、研削装置の構造を簡略にすることができる。
【図面の簡単な説明】
【図１】第１実施例の粗研削時の研削装置を示す正面断面図である。
【図２】第１実施例の仕上げ研削時の研削装置を示す正面断面図である。
【図３】第１実施例の研削装置の工具軸を示す横断面図である。
【図４】第１実施例の総型研削工具を進退させる出没機構を示す配管系統図である。
【図５】第１実施例の変形例の総型研削工具を進退させる出没機構を示す配管系統図である。
【図６】第２実施例の粗研削時の研削装置を示す正面断面図である。
【図７】第２実施例の仕上げ研削時の研削装置を示す正面断面図である。
【図８】第３実施例の粗研削時の研削装置を示す正面断面図である。
【図９】第３実施例の仕上げ研削時の研削装置を示す正面断面図である。
【図１０】第３実施例の工具軸の変形例を示す半断面図である。
【図１１】従来技術の研削装置の主要部を示す縦断面図である。
【符号の説明】
１ワーク軸
２フランジ
３ワーク
４コレットチャック
５ワーク軸本体
６カンザシ
７工具軸
８工具軸本体
９ストッパー
１０ノズル
１１総型研削工具
１２皿
２０中継ぎ
２１ナット
２２ナット
２３カップ型研削工具
Ｏ₀ 光学素子の曲率半径の球心[0001]
[Industrial application fields]
The present invention relates to means for processing a highly brittle material such as glass and ceramics into a spherical shape, and more particularly to a method and apparatus for grinding an optical element.
[0002]
[Prior art]
Conventionally, a technique disclosed in Japanese Patent Application Laid-Open No. Hei 4-22359 has been disclosed as a means for consistently performing from rough grinding to finish grinding on a single processing machine using a cup-type wheel by grinding an optical material. Has been.
[0003]
FIG. 11 shows the main part of the grinding apparatus in the prior art. Reference numeral 101 denotes a first annular grindstone, and 102 denotes a second annular grindstone, which are concentrically attached to a rotary drive shaft (not shown). The second annular grindstone 102 is attached in a state of projecting forward by the spacer 104 from the grindstone tip portion 101a of the first annular grindstone 101 in the initial processing state. The second annular grinding wheel 102 has a structure that can move in the axial direction of the rotary drive shaft via a screw 103. The second annular grinding wheel 102 is configured as a rough grinding wheel, and the first annular grinding wheel 101 is configured as a finish grinding wheel.
[0004]
Grinding in the above configuration is performed while the first annular grinding wheel 101 or the second annular grinding wheel 102 is in contact with the workpiece while rotating the rotary drive shaft. After the rough grinding process by the second annular grinding wheel 102 is completed, a tool (not shown) is inserted into the crimping hole 105, the second annular grinding wheel is removed, and the first grinding wheel 101 performs finish grinding. . This prior art also discloses a technique for switching between rough grinding and finish grinding by causing the second annular grinding wheel to protrude and retract in the axial direction by a cylinder mechanism.
[0005]
[Problems to be solved by the invention]
In the above prior art, after the rough grinding process is completed, it is necessary to temporarily suspend the process and perform an operation of removing the annular grinding wheel, and the cylinder mechanism for causing the annular grinding wheel to appear and disappear in the axial direction is complicated. Since fine adjustment is necessary to obtain a predetermined spherical shape, the operation takes time and the processing efficiency is lowered.
[0006]
Further, in finish grinding, it is possible to obtain a highly accurate finished surface by using an abrasive tool having as high a mesh as possible. However, the tool is easily crushed and the accuracy of the processed surface is deteriorated. In order to reduce this influence, lapping by spring pressure or air pressure is applied to the high mesh abrasive tool. Therefore, as in the prior art, there is a problem that it is difficult to perform highly accurate and stable processing with high efficiency using the same processing means for the rough grinding process and the finishing process.
[0007]
The present invention has been made in view of the above conventional problems, Claim 1 or 2 An object of the present invention is to provide an optical element grinding method capable of consistently high-efficiency, high-precision, and stable processing from rough grinding to finish grinding.
Claim 3, 4, 5, or 6 An object of the invention according to the present invention is to provide an optical element grinding apparatus capable of consistently high-efficiency, high-precision and stable machining from rough grinding to finish grinding.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, it is according to claim 1 or 2. Invention is tool axis In the grinding method of an optical element for grinding a workpiece into a spherical shape by a plurality of grinding tools arranged concentrically with respect to the rotation center, the plurality of grinding tools are composed of a disc type grinding tool and a total type grinding tool. The disc-type grinding tool is arranged on the outer periphery of the tool shaft, and the total-type grinding tool is arranged on the end surface of the tool shaft. After the workpiece is forcibly rotated, the disc-type grinding tool is approached from the end surface of the workpiece, and then rough grinding is performed. After the shaft is rotated, finish grinding is performed while the workpiece is pressed on the overall grinding tool and rotated in a dependent manner.
[0009]
Claim 3 or 4 The invention according to claim 1 is an optical element grinding apparatus for grinding a workpiece into a spherical shape by a plurality of grinding tools arranged concentrically with respect to the center of rotation of the tool axis, wherein the plurality of grinding tools include a cup-type grinding tool. The total grinding tool is arranged inside the cup type grinding tool, and fitted so as to be able to advance and retract along the tool axis so that it can protrude and retract relative to each other. A chuck mechanism for making the workpiece detachable and forcibly rotating, and a pressing mechanism for releasing the workpiece and pressing it in the direction of the workpiece axis, wherein the tool axis includes an axis of the workpiece and an axis of the workpiece axis. And a pivot mechanism that pivots about an axis orthogonal at the intersection.
Claim 5 or 6 The invention according to claim 1 is an optical element grinding apparatus for grinding a workpiece into a spherical shape by a plurality of grinding tools arranged concentrically with respect to a rotation center of a tool shaft, wherein the plurality of grinding tools include a disk-type grinding tool. It consists of a total grinding tool, the disc grinding tool is arranged on the outer periphery of the tool axis, the total grinding tool is arranged on the end face of the tool axis, and the workpiece axis can be moved back and forth in the axial direction, and the workpiece can be attached and detached. And a force-rotating chuck mechanism and a pressing mechanism that releases the workpiece and presses it in the direction of the workpiece axis, and the tool axis is centered on an axis perpendicular to the axis of the workpiece and the axis of the workpiece axis at the intersection It is characterized by comprising a rotating mechanism that rotates.
[0010]
[Action]
The invention according to claim 1 or 2 In action, disk type When the rough grinding by the grinding tool is completed, the tool shaft is rotated, and the finish grinding is immediately performed by the total grinding tool, so that consistent work can be continuously performed. In addition, since the finish grinding is performed on the total grinding tool while pressing the workpiece and performing the dependent rotation, a finished surface with good surface accuracy is obtained.
Claim 2 In the operation of the invention according to the present invention, in addition to the above-described operation, the finish grinding is performed while the entire grinding tool is swung around the ball, so that the finished surface can be made with higher accuracy.
[0011]
Claim 3 or 4 In the operation according to the present invention, the total grinding tool is disposed inside the cup-type grinding tool, and is fitted so as to be able to advance and retract along the tool axis so as to be able to protrude and retract relative to each other. And a pivot mechanism that pivots about an axis orthogonal to the axis of the workpiece axis at the intersection point, so that during relative grinding, relative movement between the cup-type grinding tool and the pivot mechanism To create a spherical surface on the workpiece, and during finish grinding, the grinding tool is protruded from the cup grinding tool to avoid interference with the cup grinding tool, and the pivoting mechanism gives the grinding tool a swinging motion. . In addition, since the work shaft is movable forward and backward in its axial direction, and has a chuck mechanism that makes the work detachable and forcibly rotates and a pressing mechanism that opens the work and presses it in the work shaft direction, during rough grinding, The workpiece is gripped and forcedly rotated by the chuck mechanism and fed in the axial direction. At the time of finish grinding, the chuck is opened and the workpiece is pressed onto the total grinding tool.
Claim 4 In the invention according to the present invention, in addition to the above-described operation, the radius of curvature of the overall grinding tool matches the finishing radius of curvature of the workpiece, so that the spherical surface is finished with high accuracy.
[0012]
Claim 5 or 6 In the operation of the invention according to the present invention, the disc-type grinding tool is disposed on the outer periphery of the tool shaft, the total-type grinding tool is disposed on the end surface of the tool shaft, and the tool shaft is disposed on the axis of the workpiece shaft, Since it is equipped with a rotation mechanism that rotates around an axis that is orthogonal at the intersection, the spherical surface of the workpiece is shaped by the outer peripheral surface of the disk-type grinding tool during rough grinding, and the tool axis is rotated by the rotation mechanism during finish grinding. Is rotated, and then the total grinding tool is given a swinging motion. In addition, the workpiece shaft can be moved back and forth in the axial direction, and it has a chuck mechanism that allows the workpiece to be detachable and forcibly rotated and a pressing mechanism that opens the workpiece and presses it in the workpiece axis direction. The workpiece is gripped and forcedly rotated by the mechanism and fed in the axial direction. At the time of finish grinding, the chuck is opened and the workpiece is pressed onto the total grinding tool.
Claim 6 In the operation of the invention according to the present invention, in addition to the above-mentioned operation, the radius of curvature of the longitudinal section of the disc-type grinding tool is adjusted by the finishing allowance from the finishing curvature radius of the workpiece. Therefore, the exact finishing allowance remains during rough grinding, and the spherical surface is finished with high accuracy during finish grinding.
[0013]
[Example 1]
1 to 5 show a first embodiment, FIG. 1 is a front sectional view of a grinding apparatus during rough grinding, FIG. 2 is a front sectional view of a grinding apparatus during finish grinding, and FIG. 3 is a tool shaft of the grinding apparatus. FIG. 4 is a cross-sectional view, FIG. 4 is a piping system diagram of a retracting mechanism for advancing and retracting the total grinding tool, and FIG. 5 is a piping system diagram of a retracting mechanism for advancing and retracting the modified grinding tool.
[0014]
An optical element grinding apparatus according to this embodiment will be described. In FIG. 1, the grinding apparatus is roughly divided into a work shaft 1 and a tool shaft 7. The tool shaft 7 has a cup-type grinding tool 23 screwed to one end of a cylindrical tool shaft main body 8 concentrically with the axis B of the tool shaft 7 by a screw portion 8c, and a nut 21 is cupped to prevent the looseness. A mold grinding tool 23 is fitted. A total grinding tool 11 attached to the flange 2 is fitted on the inner periphery of the cup grinding tool 23. A stopper 9 is disposed on the outer periphery of the flange 2 to hold the flange 2 so as to be able to advance and retract. The stopper 9 is fixed to one end of the intermediate piece 20. The intermediate joint 20 is fitted into the center portion of the tool shaft main body 8 and the other end thereof is screwed to the tool shaft main body 8 by a screw portion 8d, and a nut 22 is fitted to the intermediate joint 20 to prevent loosening. ing.
[0015]
The overall grinding tool 11 and the flange 2 are configured to be movable back and forth in the direction of the axis B with the stopper 9 as a guide. The range is such that the bottom surface 2b of the flange 2 and the intermediate joint 20 come into contact with each other, and the cup-type grinding tool 23 protrudes and the overall grinding tool 11 is buried (FIG. 1). Up to the position (FIG. 2) where the projection 9a comes into contact, the total grinding tool 11 protrudes and the cup grinding tool 23 is buried. The tool shaft 7 is connected to a protruding and retracting mechanism (FIG. 4) for advancing and retracting the total grinding tool 11 using air (compressed air) as a fluid via a rotary joint (not shown). As shown in FIG. 4, this in / out mechanism is composed of a compressor 51, a vacuum pump 52, and respective electromagnetic valves 53 and 54. Since the flange 2 and the stopper 9 are airtightly fitted to each other, when the solenoid valve 53 is opened, air is sent from the compressor 51 to the hole 20a of the intermediate shaft 20 of the tool shaft 7 so as to pass through the bottom surface 2b of the flange 2. Press to project the total grinding tool 11. When the solenoid valve 53 is closed and the solenoid valve 54 is opened, air is sucked by the vacuum pump, and the total grinding tool 11 is buried.
[0016]
The tool shaft main body 8 is connected to a drive source device (not shown) and is configured to be rotatable around the axis B. Further, when the tool shaft body 8 rotates, the cup-type grinding tool 23 rotates. Further, as shown in FIG. 3, the key portion 9 b of the stopper 9 and the groove portion 2 c of the flange 2 are fitted to each other, so that there is no relative movement with respect to the rotation direction of the tool shaft body 8. Therefore, the rotation of the tool shaft body 8 is configured to be transmitted to the overall grinding tool 11 via the stopper 9 and the flange 2. Further, the tool axis body 8 has an axis orthogonal to the axis A of the workpiece axis 1 and the axis B of the tool axis 7 at the intersection point as a fulcrum O. ₀ As shown in FIG. 1, a turning mechanism (not shown) that can be turned as shown in FIG.
[0017]
The cup-type grinding tool 23 and the total-type grinding tool 11 are obtained by bonding abrasive grains such as diamond powder, CBN, alumina, silicon carbide, cerium oxide, and zirconia with a metal bond, a resin bond, a metal resin bond, or a vitrified bond. is there. The processing surface 23a of the cup-type grinding tool 23 is a convex surface and has a radius of curvature R. ₁ Is the radius of curvature R of workpiece 3 ₀ Formed smaller for finishing, with center of curvature O ₁ Is the fulcrum O of the rotation mechanism of the tool shaft 7 ₀ Is set by the screw portion 8c of the tool shaft main body 8 so as to match. Further, the machining surface 11a of the overall grinding tool 11 is a convex surface, and the finishing curvature radius R ₀ R equal to ₂ Is set to
[0018]
In FIG. 1, a work shaft 1 is composed of a work shaft main body 5, a collet chuck 4 provided at an end portion thereof, and a canopy 6 provided at a central portion of the work shaft main body 5. The work shaft body 5 is configured to be rotatable about an axis A and movable in the direction of arrow C. The workpiece 3 is a disk-shaped glass material and is finally finished into a concave spherical surface 3b indicated by a broken line in FIG. The upper surface of the work 3 is affixed to the dish 12, and a recess is formed at the center of the upper surface of the dish 12, and the recess 6 can be fitted with a rod-like Kanzashi 6 with a tip. The upper end of the Kanzashi 6 is connected to a pressurizing device (not shown) attached to the work shaft body. Further, on the outer peripheral surfaces of the workpiece 3 and the dish 12, there is a tip portion of a collet chuck 4 attached to the workpiece shaft main body 5, and the outer peripheral surface of the workpiece 3 is gripped and released.
[0019]
A coolant is supplied to a contact portion during processing of the workpiece 3 with the cup-type grinding tool 23 and the total-type grinding tool 11 from a nozzle 10 connected to a coolant supply device (not shown).
[0020]
A grinding method using the grinding apparatus of the present embodiment will be described. FIG. 1 shows the state of rough grinding. In the work shaft 1, the work 3 affixed to the dish 12 is gripped by the collet chuck 4. In the tool shaft 7, the total grinding tool 11 is buried and the cup grinding tool 23 is projected. The tool axis 7 and the work axis 1 are rotated. By supplying coolant from the nozzle 10 and turning the tool shaft 7 in the α direction (at least until the processing surface 23a of the cup-type grinding tool 23 reaches the center 3a of the workpiece 3), a spherical surface is formed from the outer periphery of the workpiece 3. Perform rough grinding to create.
[0021]
In addition, the curvature radius R in the processing surface 23a of the cup type grinding tool 23 ₁ Center of O ₁ Is the fulcrum O of the rotation mechanism of the tool shaft 7 ₀ The height of the cup-type grinding tool 23 is adjusted so as to match. The adjustment is performed by loosening the nut 21 and turning the cup-type grinding tool 23 to move the screw portion 8c of the tool shaft body 8 in the direction of the axis B. Therefore, the workpiece 3 has a curvature radius R of the machining surface 23a of the cup-type grinding tool 23. ₁ A concave spherical surface 3b (surface indicated by a broken line in FIG. 1) is obtained.
[0022]
Further, the general grinding tool 11 sucks the flange 2 and the general grinding tool 11 by its protruding and retracting mechanism (FIG. 4), and is retracted to a position where the bottom surface 2 b of the flange 2 contacts the relay 20. Therefore, since the cup-type grinding tool 23 protrudes, the total-type grinding tool 11 and the workpiece 3 do not come into contact with each other.
[0023]
FIG. 2 shows the situation of finish grinding. After the workpiece axis 1 is moved upward (C direction), the tool axis 7 is moved to θ ₁ (An angle from the axis A of the workpiece axis to the center of the swing of the sphere by the total grinding tool 11). The flange 2 and the total grinding tool 11 are moved forward by the projecting mechanism of the total grinding tool 11 (FIG. 4), and held by air pressure at the position where the projection 2a of the flange 2 contacts the projection 9a of the stopper 9. In this state, the total grinding tool 11 protrudes from the cup grinding tool 23.
[0024]
Next, the collet chuck 4 is opened, and the kanzashi 6 is pushed out by a pressurizing device (not shown), and the work 3 is pressed against the machining surface 11 a of the total grinding tool 11. Coolant is supplied from the nozzle 10, and the tool shaft 7 is pivoted on the pivot mechanism O. ₀ The workpiece 3 is subjected to finish grinding by swinging the ball center around the center. At this time, the radius of curvature R of the concave spherical surface 3b of the workpiece 3 after rough grinding ₁ Is the radius of curvature R of the machining surface 11a of the overall grinding tool 11 ₂ (= R ₀ ) Is smaller than the finishing allowance, so that the contact between the workpiece 3 and the overall grinding tool 11 is the outer contact (struck from the outer peripheral portion of the workpiece 3) at the initial stage of finish grinding. Therefore, the work 3 is rotated with the rotation of the overall grinding tool 11 (dependent rotation).
[0025]
In addition, the curvature radius R in the processing surface 11a of the total grinding tool 11 in advance. ₂ Center of O ₂ Is the fulcrum O of the pivot (α) of the tool shaft 7 ₀ The height of the overall grinding tool 11 is adjusted so that The adjustment is performed by loosening the nut 22 and turning the stopper 9 to move the screw shaft 8d of the tool shaft body 8 in the direction of the axis B.
[0026]
As described above, according to the present embodiment, high-efficiency rough grinding to finish grinding can be performed consistently, and finish grinding is performed while the workpiece is pressed on the overall grinding tool and rotated dependently. Therefore, a highly accurate optical element can be obtained by stable finish grinding.
[0027]
A modification of this embodiment will be described. First, FIG. 5 shows a modified example of the device for extending and retracting the overall grinding tool. The compressor 55 is connected to the in side 56 a of the convam 56, and the out side 56 c and the suction side 56 b of the convum 56 are connected to the hole 20 a of the relay 20 through the electromagnetic valves 57 and 58. The bottom surface 2b of the flange 2 is pushed or sucked by opening and closing the electromagnetic valves 57 and 58, and the total grinding tool is moved up and down. The advantage is that the device is simplified.
[0028]
In this embodiment, the tool shaft is swung around the center of the tool and the work surface of the total grinding tool is slid in the radial direction of the workpiece during finish grinding, although there is a slight difference in spherical accuracy. Further, the swinging of the ball center is not always necessary, and the workpiece can be rotated without depending on the swinging of the ball, so that finish grinding can be performed.
Furthermore, in this embodiment, the cup-type grinding tool is fixed to the tool shaft main body, and the total grinding tool is projected and retracted in the axial direction. Instead, the total grinding tool is fixed to the tool shaft main body. In addition, the cup-type grinding tool can be raised and lowered. In this case, the grinding apparatus has a structure in which the cup-type grinding tool is connected to the retracting mechanism.
[0029]
[Example 2]
6 to 7 show a second embodiment, FIG. 6 is a front sectional view of a grinding apparatus during rough grinding, and FIG. 7 is a front sectional view during finish grinding. This embodiment is different from the first embodiment in that the workpiece is changed from a concave shape to a convex shape and the structure of the protruding and retracting mechanism of the total grinding tool. Others are the same as those of the first embodiment, and the same members are denoted by the same reference numerals and the description thereof is omitted.
[0030]
In FIG. 6, the flange 2 is connected to a piston portion 24 a of a cylinder 24 via a bearing 25 so as to be rotatable and advanceable and retractable. Further, the processing surface 23a of the cup-type grinding tool 23 is concave and has a radius of curvature R. ₁ Is the radius of curvature R of workpiece 3 ₀ The machining surface 11a of the overall grinding tool 11 is concave and has a radius of curvature R. ₂ Is the finish curvature radius R ₀ Are formed identically. Other structures of the grinding apparatus are the same as those in the first embodiment.
[0031]
A grinding method using the grinding apparatus of the present embodiment will be described. FIG. 6 shows the state of rough grinding. In the work shaft 1, the work 3 affixed to the dish 12 is gripped by the collet chuck 4. In the tool shaft 7, the total grinding tool 11 is buried and the cup grinding tool 23 is projected. The tool axis 7 and the work axis 1 are rotated. By supplying coolant from the nozzle 10 and turning the tool shaft 7 in the α direction (at least until the processing surface 23a of the cup-type grinding tool 23 reaches the center 3a of the workpiece 3), a spherical surface is formed from the outer periphery of the workpiece 3. Perform rough grinding to create.
[0033]
In addition, the curvature radius R in the processing surface 23a of the cup type grinding tool 23 ₁ Center of O ₁ Is the fulcrum O of the rotation mechanism of the tool shaft 7 ₀ The height of the cup-type grinding tool 23 is adjusted so as to match. The adjustment is performed by loosening the nut 21 and turning the cup-type grinding tool 23 to move the screw portion 8c of the tool shaft body 8 in the direction of the axis B. Therefore, the workpiece 3 has a curvature radius R of the machining surface 23a of the cup-type grinding tool 23. ₁ A convex spherical surface 3b (a surface indicated by a broken line in FIG. 6) is obtained.
[0034]
Further, the general grinding tool 11 is pulled back to the position where the bottom surface 2 b of the flange 2 contacts the intermediate joint 20 by pulling back the flange 2 and the general grinding tool 11 by the cylinder 24. Therefore, since the cup-type grinding tool 23 protrudes, the total-type grinding tool 11 and the workpiece 3 do not come into contact with each other.
[0035]
FIG. 7 shows the situation of finish grinding. After the workpiece axis 1 is moved upward (C direction), the tool axis 7 is moved to θ ₁ (An angle from the axis A of the workpiece axis to the center of the swing of the sphere by the total grinding tool 11). The flange 24 and the general grinding tool 11 are advanced by a cylinder 24 connected to the general grinding tool 11 and held by air pressure at a position where the projection 2 a of the flange 2 contacts the projection 9 a of the stopper 9. In this state, the total grinding tool 11 protrudes from the cup grinding tool 23.
[0036]
Next, the collet chuck 4 is opened, and the kanzashi 6 is pushed out by a pressurizing device (not shown), and the work 3 is pressed against the machining surface 11 a of the total grinding tool 11. Coolant is supplied from the nozzle 10, and the tool shaft 7 is pivoted on the pivot mechanism O. ₀ The workpiece 3 is subjected to finish grinding by swinging the ball center around the center. At this time, the radius of curvature R of the convex spherical surface 3b of the workpiece 3 after rough grinding. ₁ Is the radius of curvature R of the machining surface 11a of the overall grinding tool 11 ₂ (= R ₀ ) Larger than the finishing allowance, the contact between the workpiece 3 and the total grinding tool 11 is the outer contact (struck from the outer peripheral portion of the workpiece 3) at the initial stage of finish grinding. Therefore, the work 3 is rotated with the rotation of the overall grinding tool 11 (dependent rotation).
[0037]
In addition, the curvature radius R in the processing surface 11a of the total grinding tool 11 in advance. ₂ Center of O ₂ Is the fulcrum O of the pivot (α) of the tool shaft 7 ₀ The height of the overall grinding tool 11 is adjusted so that The adjustment is performed by loosening the nut 22 and turning the stopper 9 to move the screw shaft 8d of the tool shaft body 8 in the direction of the axis B.
[0038]
As described above, according to the present embodiment, even a convex workpiece can be processed efficiently from rough grinding to finish grinding with high efficiency, and the workpiece is pressed onto the overall grinding tool to be subordinate. Since finish grinding is performed while rotating, a highly accurate optical element can be obtained by stable finish grinding.
[0039]
Next, in this embodiment, the cup-type grinding tool is fixed to the tool shaft main body, and the total grinding tool is projected and retracted in the axial direction. Instead, the total grinding tool is mounted on the tool shaft main body. It can be fixed and the cup-type grinding tool can be raised and lowered. In this case, the grinding apparatus has a structure in which the cup-type grinding tool is connected to the cylinder. In this embodiment, the cylinder uses air (compressed air), but a hydraulic cylinder or an air-hydro cylinder can also be used.
[0040]
[Example 3]
8 to 10 show a third embodiment, FIG. 8 is a front sectional view of a grinding apparatus during rough grinding, FIG. 9 is a front sectional view during finish grinding, and FIG. 10 is a half sectional view showing a modification of a tool shaft. FIG. Since the present embodiment is characterized only by the configuration of the tool axis, the configuration of the workpiece axis and the like are the same as those of the first and second embodiments, and the same members are denoted by the same reference numerals and description thereof is omitted.
[0041]
In FIG. 8, the electrodeposition tool 31 of diamond abrasive grains, which is a disk-type grinding tool, is provided on the outer peripheral surface of the tool shaft body 8 so as to have a longitudinal cross-sectional radius of curvature R of the processing surface 31a. ₁ Center of O ₁ And fulcrum O of the rotation mechanism of the tool shaft 7 ₀ It is mounted so as to match. Further, the flange 2 to which the general grinding tool 11 is attached is screwed coaxially to the screw portion 8c of the tool shaft body 8 at its screw portion 2c, and a nut 30 is fitted to the screw portion 2c to prevent loosening. Yes. The radius of curvature R of the machining surface 11a of the overall grinding tool 11 ₂ Is the finishing radius of curvature R ₀ Since the workpiece 3 is concave, the curvature radius R of the longitudinal section of the electrodeposition tool 31 ₁ Is the finishing radius of curvature R ₀ Smaller than the finishing allowance. The outer diameter D of the electrodeposition tool 31 _k When the width W is smaller than the outer diameter of the workpiece 3 as shown in FIG. ₁ Form exactly twice as much as However, when the width W is larger than the outer diameter of the workpiece 3, the longitudinal cross-sectional curvature radius R of the electrodeposition tool 31 is set to less than 2 times. ₁ The spherical shape shaping by may not interfere.
[0042]
The tool shaft main body 8 is connected to a drive source device (not shown) and is configured to be rotatable around the axis B. The rotation of the tool shaft main body 8 is configured to be transmitted to the electrodeposition tool 31 and the overall grinding tool 11. Further, the tool axis body 8 has an axis orthogonal to the axis A of the workpiece axis 1 and the axis B of the tool axis 7 at the intersection point as a fulcrum O. ₀ And a pivot mechanism (not shown) that can be pivoted and pivoted (in the α direction).
[0043]
A grinding method using the grinding apparatus of the present embodiment will be described. FIG. 8 shows the state of rough grinding. In the work shaft 1, the work 3 affixed to the dish 12 is gripped by the collet chuck 4. The tool shaft 7 is tilted by the rotation mechanism until the axis B of the tool shaft 7 is perpendicular to the axis A of the work shaft 1. The tool axis 7 and the work axis 1 are rotated. The coolant is supplied from the nozzle 10, and the workpiece 3 is roughly ground by feeding the workpiece axis downward (C direction). On the lower surface of the work 3, a concave spherical surface 3b is formed by the rotation of the electrodeposition tool 31, the forced rotation of the work shaft 1, and the feeding in the C direction.
[0044]
FIG. 9 shows the situation of finish grinding. After the workpiece axis 1 is moved upward (C direction), the tool axis 7 is moved to θ ₀ (An angle from the axis A of the work shaft to the center of the sphere swing by the total grinding tool 11). Next, the collet chuck 4 is opened, and the kanzashi 6 is pushed out by a pressurizing device (not shown), and the work 3 is pressed against the machining surface 11 a of the total grinding tool 11. Coolant is supplied from the nozzle 10, and the tool shaft 7 is pivoted on the pivot mechanism O. ₀ The workpiece 3 is subjected to finish grinding by swinging the ball center around the center. At this time, the radius of curvature R of the concave spherical surface 3b of the workpiece 3 after rough grinding ₁ Is the finish curvature radius R ₂ (= R ₀ Therefore, at the initial stage of finish grinding, the contact between the workpiece 3 and the total grinding tool 11 is an outer contact (struck from the outer peripheral portion of the workpiece 3). Therefore, the work 3 is rotated with the rotation of the overall grinding tool 11 (dependent rotation).
[0045]
In addition, the curvature radius R in the processing surface 11a of the total grinding tool 11 in advance. ₂ Center of O ₂ Is the fulcrum O of the rotation mechanism ₀ The height of the overall grinding tool 11 is adjusted so as to match the above. The adjustment is performed by loosening the nut 30 and turning the flange 2 to move the threaded portion 8e of the tool shaft body 8 in the direction of the axis B.
[0046]
According to the present embodiment, the same effect as that of the first embodiment can be obtained in the concave workpiece, and the structure of the grinding apparatus can be simplified because the protruding and retracting mechanism of the total grinding tool is not necessary.
[0047]
A modification of this embodiment will be described. First, FIG. 10 shows a modified example of the tool axis, which is characterized in that the electrodeposition tool 41 is attached to the axis B of the tool axis 7 at an inclination angle of γ. When rough grinding is performed, the tool shaft 7 is tilted and rotated to the inclination angle γ of the electrodeposition tool 41, and the workpiece shaft 1 is sent downward (C direction). In this case, since the machining surface 41a of the electrodeposition tool 41 starts to contact the workpiece 3 obliquely from the lower end surface, the cutting is smoothly performed.
[0048]
Next, in this embodiment, an electrodeposition tool of diamond abrasive grains was used as the disk-type grinding tool. However, as in the case of the overall grinding tool, a disk-type bonded with abrasive grains such as CBN described in the first embodiment. A grinding tool may be used.
Further, in this embodiment, the case of grinding a concave workpiece has been described. However, a disk-type grinding tool having a concave vertical cross-sectional shape of the machining surface and a width larger than the outer diameter of the workpiece, and a concave machining surface are provided. A convex workpiece can be ground by using the entire grinding tool. In this case, the curvature radius of the longitudinal section of the processed surface of the disk-type grinding tool is larger than the finishing curvature radius of the workpiece by the finishing allowance.
Furthermore, in the present embodiment, the center of the tool shaft is swung and finish grinding is performed by the overall grinding tool. However, as in the first embodiment, although the finished surface accuracy is slightly different, It is not always necessary to oscillate the ball center, and the workpiece is dependently rotated only by pressing the workpiece onto the total grinding tool and rotating the tool axis, so that finish grinding can be performed.
[0049]
【The invention's effect】
Inventions according to claims 1 and 2 According to high efficiency In addition, machining from rough grinding to finish grinding can be performed consistently, and the finish grinding is performed while the workpiece is pressed against the total grinding tool and rotated in a dependent manner, so high precision is achieved through stable finish grinding. An optical element can be obtained, and a structure for the grinding apparatus can be simplified because there is no need for a projecting / retracting mechanism of the total grinding tool. Claim 2 According to the invention according to the present invention, in addition to the above effects, the finish grinding is performed while the central grinding tool is swung around the center of the ball, so that a more accurate finished surface can be obtained. Claims 3-4 According to the invention according to the invention, it is possible to perform processing from rough grinding to finish grinding with high efficiency in a consistent manner, and perform finish grinding while pressing the workpiece on the overall grinding tool and subjecting it to dependent rotation. Thus, a highly accurate optical element grinding apparatus can be provided. Claims 5-6 According to the invention according to the invention, it is possible to perform processing from rough grinding to finish grinding with high efficiency in a consistent manner, and perform finish grinding while pressing the workpiece on the overall grinding tool and subjecting it to dependent rotation. Thus, it is possible to provide a grinding apparatus for an optical element with high accuracy, and it is not necessary to have a mechanism for projecting and retracting the entire grinding tool, so that the structure of the grinding apparatus can be simplified.
[Brief description of the drawings]
FIG. 1 is a front sectional view showing a grinding apparatus for rough grinding according to a first embodiment.
FIG. 2 is a front sectional view showing a grinding apparatus at the time of finish grinding in the first embodiment.
FIG. 3 is a cross-sectional view showing a tool axis of the grinding apparatus of the first embodiment.
FIG. 4 is a piping system diagram showing a retracting mechanism for advancing and retracting the overall grinding tool of the first embodiment.
FIG. 5 is a piping system diagram showing a retracting mechanism for advancing and retracting a total grinding tool according to a modification of the first embodiment.
FIG. 6 is a front sectional view showing a grinding apparatus for rough grinding according to a second embodiment.
FIG. 7 is a front sectional view showing a grinding apparatus at the time of finish grinding in a second embodiment.
FIG. 8 is a front sectional view showing a grinding apparatus for rough grinding according to a third embodiment.
FIG. 9 is a front sectional view showing a grinding apparatus at the time of finish grinding according to a third embodiment.
FIG. 10 is a half sectional view showing a modification of the tool shaft of the third embodiment.
FIG. 11 is a longitudinal sectional view showing a main part of a conventional grinding apparatus.
[Explanation of symbols]
1 Work axis
2 Flange
3 Work
4 Collet chuck
5 Work shaft body
6 Kanzashi
7 Tool axis
8 Tool axis body
9 Stopper
10 nozzles
11 Total grinding tool
12 dishes
20 relay
21 Nut
22 nuts
23 Cup type grinding tool
O ₀ Sphere of curvature radius of optical element

Claims

In the grinding method of an optical element for grinding a workpiece into a spherical shape by a plurality of grinding tools arranged concentrically with respect to the rotation center of the tool axis,
The plurality of grinding tools include a disk-type grinding tool and a total-type grinding tool. The disk-type grinding tool is disposed on the outer periphery of the tool shaft, and the total-type grinding tool is disposed on the end surface of the tool shaft to forcibly rotate the workpiece. An optical disc characterized in that the disc-type grinding tool is approached from the end face of the workpiece, rough grinding is performed, the tool shaft is rotated, and then the workpiece is pressed onto the overall grinding tool and subjected to finish grinding while being rotated dependently. Element grinding method.

The optical element grinding method according to claim 1 , wherein the finish grinding is performed by swinging the central grinding tool around the spherical center of the radius of curvature of the optical element.

In an optical element grinding apparatus for grinding a workpiece into a spherical shape with a plurality of grinding tools arranged concentrically with respect to the rotation center of the tool axis,
The plurality of grinding tools include a cup-type grinding tool and a total-type grinding tool, and the total-type grinding tool is arranged inside the cup-type grinding tool and can be moved forward and backward along the tool axis so as to be able to appear and retract relative to each other. The workpiece shaft is provided with a chuck mechanism that is movable forward and backward in the axial direction, detachably and forcibly rotates the workpiece, and a pressing mechanism that opens the workpiece and presses it in the workpiece axis direction, the tool shaft Is a grinding device for an optical element, characterized in that it comprises a rotation mechanism that rotates about the axis orthogonal to the axis of the workpiece and the axis of the work axis.

4. The optical element grinding apparatus according to claim 3, wherein the radius of curvature of the overall grinding tool coincides with the finishing radius of curvature of the workpiece.

In an optical element grinding apparatus for grinding a workpiece into a spherical shape with a plurality of grinding tools arranged concentrically with respect to the rotation center of the tool axis,
The plurality of grinding tools include a disk-type grinding tool and a total-type grinding tool, the disk-type grinding tool is disposed on the outer periphery of the tool shaft, the total-type grinding tool is disposed on the end surface of the tool shaft, A chuck mechanism that can move forward and backward in the axial direction, detachably and forcibly rotate the workpiece, and a pressing mechanism that opens the workpiece and presses it in the workpiece axis direction, the tool axis being the axis of the workpiece and the axis of the workpiece axis An optical element grinding apparatus comprising a rotation mechanism that rotates about an axis orthogonal to the center at an intersection thereof.

The radius of curvature of the longitudinal section of the disk-type grinding tool is adjusted by the finishing allowance from the finishing curvature radius of the workpiece, and the curvature radius of the total-type grinding tool is equal to the finishing curvature radius of the workpiece. 6. An optical element grinding apparatus according to claim 5, wherein: