JP4216557B2

JP4216557B2 - Polishing apparatus and polishing method

Info

Publication number: JP4216557B2
Application number: JP2002286901A
Authority: JP
Inventors: 邦博津田; 仁徳安田; 寅臣永田; 幸裕楠本; 桂吾渡辺
Original assignee: 株式会社エーエスエー・システムズ
Priority date: 2002-09-30
Filing date: 2002-09-30
Publication date: 2009-01-28
Anticipated expiration: 2022-09-30
Also published as: JP2004122255A

Description

【０００１】
【発明の属する技術分野】
本発明は、研磨装置及び研磨方法に関するものである。
【０００２】
【従来の技術】
従来より、金型の製造に際しては、ＮＣ加工装置などを用いた自動化が進められてきている。
【０００３】
しかしながら、金型製造の仕上げ工程である研磨工程にあっては、金型表面を高精度に研磨する研磨装置が存在しないことから、熟練者による研磨工具を用いた手作業で行われていた。
【０００４】
そのため、近年では、研磨工程を自動的に行う研磨装置がいくつか提案されてきている。
【０００５】
たとえば、特許文献１に開示されている研磨装置では、多関節ロボットのアームの先端に回転駆動機構を取付け、同回転駆動機構に研磨工具としての砥石を取付けており、回転駆動機構で砥石を回転させながら被研磨対象物の被研磨面に沿って砥石を移動させることによって研磨を行うように構成している。
【０００６】
また、特許文献２に開示されている研磨装置では、マシニングセンタに回転駆動機構を取付け、同回転駆動機構に研磨工具としての砥石を取付けており、回転駆動機構で砥石を回転させながら被研磨対象物の被研磨面に沿って砥石を移動させることによって研磨を行うように構成している。
【０００７】
また、特許文献３に開示されている研磨装置では、超音波振動子に研磨工具としての振動板を取付けており、被研磨対象物の被研磨面に振動板を当接し、超音波振動子で振動板を振動させることによって研磨を行うように構成している。
【０００８】
【特許文献１】
特開平７−１００７５４号公報
【０００９】
【特許文献２】
特開平１０−１６６２６７号公報
【００１０】
【特許文献３】
特開平１１−３４７８９４号公報
【００１１】
【発明が解決しようとする課題】
ところが、上記従来の研磨装置にあっても被研磨対象物の被研磨面を高精度に研磨することができなかった。
【００１２】
すなわち、上記従来の研磨装置にあっては、回転駆動機構や超音波振動子を用いて研磨工具を回転又は振動させることによって研磨を行っていたため、回転や振動の発生時に駆動ノイズも同時に発生してしまい、かかる駆動ノイズの影響で研磨工具の研磨面と被研磨対象物の被研磨面との間の押圧力を精度よく検出することができず、これにより、研磨工具の位置や姿勢を高精度に制御することができなかった。
【００１３】
また、回転や振動による研削力が強く作用してしまい、研磨時に被研磨面に作用する研磨力を微調整することが困難であった。
【００１４】
また、多関節ロボットやマシニングセンタによって研磨工具だけでなく回転駆動機構や超音波振動子などの重量物をも持ち上げなければならず、これによっても、研磨時に被研磨面に作用する研磨力を微調整することが困難であった。
【００１５】
このように、従来の研磨装置では、金型などの表面を大雑把に研磨することはできたが、研磨時に被研磨面に作用する研磨力を微調整することができなかったため、複雑な曲面を有する金型の仕上げ加工などには実用的ではなかった。
【００１６】
【課題を解決するための手段】
そこで、請求項１に係る本発明では、被研磨対象物の被研磨面の曲率半径よりも小さな曲率半径の球面状の研磨面を有する研磨工具を変位移動可能なアームの先端に取付け、同アームを研磨工具の姿勢を保持したまま変位させることによって研磨工具の研磨面を被研磨対象物の被研磨面に点接触状態にて押圧しながら被研磨対象物の被研磨面に沿って移動させ、しかも、研磨工具の先端部の軌道を予め用意しておいた初期軌道に沿ってフィードフォワード制御するとともに、研磨工具の研磨面と被研磨対象物の被研磨面との押圧力と研磨工具先端部の移動により研磨工具の研磨面と被研磨対象物の被研磨面との間で生じる運動摩擦力と粘性摩擦力との合力が所定の研磨力となるように、研磨工具の研磨面と被研磨対象物の被研磨面との接触点における研磨工具の法線方向速度と接線方向速度とをフィードバック制御によって決定するとともに、これらの法線方向速度と接線方向速度とからアームの変移量を決定することにより、研磨工具の初期軌道を適宜修正しながら研磨工具を移動させ、更に、研磨工具の初期軌道を修正する際に、研磨工具の先端部が実際に通過する実軌道を記憶しておき、次回の研磨作業時に前回の実軌道を初期軌道として用いる研磨装置を提供する。
【００１７】
また、請求項２に係る本発明では、前記請求項１に係る本発明において、被研磨対象物の被研磨面に沿って移動する途中で研磨工具先端部の研磨面を変更することにした。
【００１８】
また、請求項３に係る本発明では、被研磨対象物の被研磨面の曲率半径よりも小さな曲率半径の球面状の研磨面を有する研磨工具を被研磨対象物の被研磨面に点接触状態にて押圧するとともに、研磨工具の姿勢を保持したまま研磨工具の研磨面を被研磨対象物の被研磨面に沿って移動させ、しかも、被研磨対象物の被研磨面の曲率半径よりも小さな曲率半径の球面状の研磨面を有する研磨工具を被研磨対象物の被研磨面に点接触状態にて押圧するとともに、研磨工具の姿勢を保持したまま研磨工具の研磨面を被研磨対象物の被研磨面に沿って移動させ、しかも、研磨工具の先端部の軌道を予め用意しておいた初期軌道に沿ってフィードフォワード制御するとともに、研磨工具先端部と被研磨面との押圧力と研磨工具先端部の移動により研磨工具の研磨面と被研磨対象物の被研磨面との間で生じる運動摩擦力と粘性摩擦力との合力が所定の研磨力となるべく、研磨工具の研磨面と被研磨対象物の被研磨面との接触点における研磨工具の法線方向速度と接線方向速度とをフィードバック制御によって決定するとともに、これらの法線方向速度と接線方向速度とから、研磨工具の初期軌道を適宜修正しながら研磨工具を移動させ、更に、研磨工具の初期軌道を修正する際に、研磨工具の先端部が実際に通過する実軌道を記憶しておき、次回の研磨作業時に前回の実軌道を初期軌道として用いるべく制御することにした。
【００１９】
また、請求項４に係る本発明では、前記請求項３に係る本発明において、被研磨対象物の被研磨面に沿って移動する途中で研磨工具先端部の研磨面を変更することにした。
【００２０】
【発明の実施の形態】
本発明に係る研磨装置は、多関節ロボットのアームの先端に取付けた研磨工具としての砥石で被研磨対象物の被研磨面を研磨するものである。
【００２１】
そして、被研磨対象物の被研磨面の曲率半径よりも小さな曲率半径の球面状の研磨面を有する研磨工具を変位移動可能なアームの先端に取付け、同アームを研磨工具の姿勢を保持したまま変位させることによって研磨工具の研磨面を被研磨対象物の被研磨面に点接触状態にて押圧しながら被研磨対象物の被研磨面に沿って移動させ、しかも、研磨工具の研磨面と被研磨対象物の被研磨面との押圧力と研磨工具先端部の移動により研磨工具の研磨面と被研磨対象物の被研磨面との間で生じる運動摩擦力と粘性摩擦力との合力が所定の研磨力となるようにアームの変位量を制御すべく構成したものである。
【００２２】
このように、本発明に係る研磨装置では、研磨工具の姿勢を保持したまま変位させており、研磨工具の研磨面と被研磨対象物の被研磨面との押圧力と研磨工具先端部の移動により研磨工具の研磨面と被研磨対象物の被研磨面との間で生じる運動摩擦力と粘性摩擦力との合力を研磨力として被研磨面に作用させている。
【００２３】
したがって、本発明に係る研磨装置では、従来の研磨装置とは異なり、回転駆動機構や超音波振動子を用いて研磨工具を回転又は振動させることをしていないため、研磨作業時に駆動ノイズが発生するのを防止することができ、研磨工具の研磨面と被研磨対象物の被研磨面との間の押圧力を精度よく検出することができ、これにより、研磨工具の位置や姿勢を高精度に制御することができる。
【００２４】
しかも、研磨工具を回転や振動させないことから、研磨力を必要最小限に抑制することができ、研磨時に被研磨面に作用する研磨力を容易に微調整することができる。
【００２５】
また、多関節ロボットのアームで軸付き砥石などの比較的軽量な研磨工具だけを持ち上げればよくなり、これによっても、研磨時に被研磨面に作用する研磨力を容易に微調整することができる。
【００２６】
特に、被研磨対象物の被研磨面に沿って移動する途中で研磨工具先端部の研磨面を変更させた場合には、研磨工具の先端部を全体にわたって研磨面として有効に活用することができ、これにより、研磨工具の長寿命化を図ることができる。
【００２７】
このように、本発明に係る研磨装置では、研磨時に被研磨面に作用する研磨力を容易に微調整することができるので、複雑な曲面を有する金型の仕上げ加工などに実用的に適用することができる。
【００２８】
なお、本発明は、上記研磨装置の構造に特徴を有するとともに、その制御方法である研磨方法にも特徴を有するものである。
【００２９】
以下に、本発明の具体的な実施の形態について図面を参照しながら説明する。
【００３０】
本発明に係る研磨装置１は、図１及び図２に示すように、多関節ロボット２のアーム３の先端部に力覚センサ４の上面を取付け、同力覚センサ４の下面に研磨工具５をアタッチメント６を介して着脱自在に取付けている。図中、12は多関節ロボット２のアーム３の位置や姿勢を変更させるための制御装置である。
【００３１】
多関節ロボット２は、アーム３の位置や姿勢を変更制御することによってアーム３の先端に設けた研磨工具５を変位移動させることができるものであればよく、本実施例では、オープンアーキテクチャ型の産業用ロボットを用いている。
【００３２】
力覚センサ４は、右手座標系におけるＸ、Ｙ、Ｚ方向の力覚値を独立して検出することができる３自由度のものを用いている。
【００３３】
研磨工具５は、図２に示すように、アタッチメント６に取付ける支持体７の先端部に略筒状の砥石８を連設している。
【００３４】
しかも、研磨工具５（砥石８）の先端部は、図２及び図３に示すように、被研磨対象物９の被研磨面10の曲率半径ｒよりも小さな曲率半径Ｒの半球面状の研磨面11としている。
【００３５】
これは、被研磨対象物９の被研磨面10の全面にわたって研磨工具５の研磨面11で研磨できるようにするためである。なお、被研磨対象物９の被研磨面10が３次元自由曲面であって凹凸がある場合には、その凹凸部分での曲率半径ｒを考慮して研磨工具５の研磨面11の曲率半径Ｒを決定する。
【００３６】
研磨装置１は、以上のように構成しており、制御装置12で多関節ロボット２を次に説明するように制御することによって研磨工具５の研磨面11で被研磨対象物９の被研磨面10を研磨する。
【００３７】
まず、制御装置12は、多関節ロボット２のアーム３を研磨工具５の姿勢を保持したまま変位させることによって、研磨工具５の研磨面11を被研磨対象物９の被研磨面10に点接触状態にて押圧させる（図３中、符号(a)で示す。）。なお、本実施例では、研磨工具５の姿勢を鉛直下向き（−Ｚ方向）の姿勢としている。研磨工具５の姿勢は、特に鉛直下向き姿勢に限定されるものではなく、いかなる姿勢であってもよく、その姿勢を保持したままアーム３によって研磨工具５を変位移動させることができればよい。
【００３８】
次に、制御装置12は、多関節ロボット２のアーム３を研磨工具５の姿勢を保持したまま変位させることによって、研磨工具５の研磨面11を被研磨対象物９の被研磨面10に沿って移動させる（図３中、符号(b),(c),(d),(e)で示す。)。
【００３９】
ここで、制御装置12は、多関節ロボット２のアーム３で研磨工具５を変位移動させる際に、研磨工具５の研磨面11を被研磨対象物９の被研磨面10に点接触させた状態を保持しながら変位移動させるようにしている。
【００４０】
しかも、制御装置12は、研磨工具５の研磨面11と被研磨対象物９の被研磨面11との押圧力ｆと研磨工具５の先端部（研磨面11）の移動によって研磨工具５の研磨面11と被研磨対象物９の被研磨面10との間で発生する運動摩擦力f dと粘性摩擦力fsとの合力Ｆが所定の研磨力Ｆdとなるようにアーム３の変位量を制御するようにしている。
【００４１】
ここで、研磨工具５の研磨面11と被研磨対象物９の被研磨面11との押圧力ｆは、右手座標系におけるX,Y,Z各方向の押圧力成分をそれぞれfx,fy,fzとすると、押圧力ｆ（fx,fy,fz）と表記され、研磨工具５の研磨面11と被研磨対象物９の被研磨面10との接触点における研磨工具５の法線方向速度Vn（Vnx,Vny,Vnz）により与えられる。
【００４２】
また、研磨工具５の先端部（研磨面11）の移動によって発生する運動摩擦力fdは、運動摩擦係数をμとし、研磨工具５の研磨面11と被研磨対象物９の被研磨面10との接触点における研磨工具５の接線方向速度をVt（Vtx,Vty,Vtz）とすると、fd＝−μ・｜ｆ｜・（Vt／｜Vt｜）と表され、運動摩擦係数μと研磨工具５の研磨面11と被研磨対象物９の被研磨面10との接触点における研磨工具５の接線方向速度Vt（Vtx,Vty,Vtz）とにより与えられる。
【００４３】
また、研磨工具５の研磨面11と被研磨対象物９の被研磨面10との間で発生する粘性摩擦力fsは、粘性摩擦係数をηとすると、fs＝−η・Vtと表され、粘性摩擦係数ηと研磨工具５の研磨面11と被研磨対象物９の被研磨面10との接触点における研磨工具５の接線方向速度Vt（Vtx,Vty,Vtz）とにより与えられる。
【００４４】
したがって、制御装置12は、押圧力ｆと運動摩擦力fdと粘性摩擦力fsとの合力Ｆ（Ｆ＝f＋fd＋fs＝ｆ−μ・｜ｆ｜・（Vt／｜Vt｜）−η・Vt）が予め設定しておいた所定の研磨力と等しくなるように、研磨工具５の研磨面11と被研磨対象物９の被研磨面10との接触点における研磨工具５の法線方向速度Vnと接線方向速度Vtとをフィードバック制御により決定し、かかる法線方向速度Vnと接線方向速度Vtとからアーム３の変位量を決定するようにしている。
【００４５】
なお、多関節ロボット２のアーム３の力制御については、公知の制御方法を用いることができる（たとえば、特願平１０−１７３５０９号公報や特願平１１−２４１７７１号公報参照。）。
【００４６】
そして、制御装置12は、予め用意しておいた初期軌道Ｔ¹（Ｔ¹x (j) ,Ｔ¹y (j) ,Ｔ¹z (j)）を適宜修正しながら研磨工具５を移動させる。ここで、ｊ＝1,2,3・・・ｋ（ｋは正整数）であり、初期軌道Ｔ¹はｋ行のベクトルから構成されている。
【００４７】
これにより、研磨工具５の研磨面11が被研磨対象物９の被研磨面10と点接触しながら移動し、被研磨対象物９の被研磨面10が研磨工具５の研磨面11によって研磨される。ここで、初期軌道Ｔ¹は、研磨工具５の先端部が半径Ｒの半球面であることを考慮し、研磨工具５の研磨面11が被研磨対象物９の被研磨面10と点接触しながら移動できるようにオフセットした研磨工具５の先端中心位置での軌道としている。
【００４８】
すなわち、制御装置12は、研磨工具５の先端部の軌道を初期軌道Ｔ¹に沿ってフィードフォワード制御するとともに、前述したようにして押圧力ｆと運動摩擦力fdと粘性摩擦力fsとの合力Ｆが所定の研磨力Ｆdとなるように法線方向速度Vnと接線方向速度Vtとをフィードバック制御によって決定するとともに、これらの法線方向速度Vnと接線方向速度Vtとからアーム３の変位量を決定し、これにより初期軌道Ｔ¹を適宜修正するようにしている。
【００４９】
その際に、制御装置12は、初期軌道Ｔ¹に修正を加えた軌道、すなわち、研磨工具５の先端部が実際に通過する実軌道をＴⁿ（Ｔⁿx (j) ,Ｔⁿy (j) ,Ｔⁿz (j)）（ここで、ｎは回数を示す。）として記憶しておき、次回の研磨作業時に前回の実軌道Ｔⁿを初期の目標軌道として用いることができるようにしている。
【００５０】
このように、初期の目標軌道を更新していくことで、被研磨対象物９の研磨作業を繰り返し行うことによって目標軌道が最適化され、研磨力Ｆの偏差を可及的に小さくすることができ、被研磨対象物９の被研磨面10をより一層高精度に研磨することができる。
【００５１】
また、本実施例では、制御装置12は、研磨工具５の研磨面11を被研磨対象物９の被研磨面10に沿って移動させる途中で、研磨工具５の先端部の研磨面11を変更させるようにしている。
【００５２】
すなわち、制御装置12は、研磨工具５の研磨面11と被研磨対象物９の被研磨面10との間で回転運動による摩擦力が作用しない範囲でアーム３の先端部を回転させながら、研磨工具５の研磨面11を被研磨対象物９の被研磨面10に沿って移動させている。なお、研磨工具５の研磨面11の変更は、研磨工具５を非常に低速度で連続的に回転させてもよく、また、所定箇所において研磨工具５を非常に低速度で断続的に回転させてもよい。
【００５３】
このように、研磨工具５の研磨面11の変更することによって、研磨工具５の先端部を全体にわたって研磨面11として有効に活用することができ、これにより、研磨工具５の長寿命化を図ることができる。
【００５４】
【発明の効果】
本発明は、以上に説明したような形態で実施され、以下に記載されるような効果を奏する。
【００５５】
すなわち、本発明では、研磨工具の姿勢を保持したまま変位させており、研磨工具の研磨面と被研磨対象物の被研磨面との押圧力と研磨工具先端部の移動により研磨工具の研磨面と被研磨対象物の被研磨面との間で生じる運動摩擦力と粘性摩擦力との合力を研磨力として被研磨面に作用させている。
【００５６】
そのため、従来の研磨装置とは異なり、回転駆動機構や超音波振動子を用いて研磨工具を回転又は振動させることをしていないので、研磨作業時に駆動ノイズが発生するのを防止することができ、研磨工具の研磨面と被研磨対象物の被研磨面との間の研磨力を精度よく検出することができ、これにより、研磨工具の位置や姿勢を高精度に制御することができる。
【００５７】
しかも、研磨工具を回転や振動させないことから、研磨力を必要最小限に抑制することができ、研磨時に被研磨面に作用する研磨力を容易に微調整することができる。
【００５８】
また、多関節ロボットのアームで比較的軽量な研磨工具だけを持ち上げればよくなり、これによっても、研磨時に被研磨面に作用する研磨力を容易に微調整することができる。
【００５９】
このように、本発明では、研磨時に被研磨面に作用する研磨力を容易に微調整することができ、これにより、被研磨対象物の被研磨面を精度よく研磨することができる。
また、本発明では、研磨工具の先端部の軌道を予め用意しておいた初期軌道に沿ってフィードフォワード制御するとともに、研磨工具の研磨面と被研磨対象物の被研磨面との押圧力と研磨工具先端部の移動により研磨工具の研磨面と被研磨対象物の被研磨面との間で生じる運動摩擦力と粘性摩擦力との合力が所定の研磨力となるように、研磨工具の研磨面と被研磨対象物の被研磨面との接触点における研磨工具の法線方向速度と接線方向速度とをフィードバック制御によって決定するとともに、これらの法線方向速度と接線方向速度とからアームの変移量を決定することにより、研磨工具の初期軌道を適宜修正しながら研磨工具を移動させ、更に、研磨工具の初期軌道を修正する際に、研磨工具の先端部が実際に通過する実軌道を記憶しておき、次回の研磨作業時に前回の実軌道を初期軌道として用いるようにしている。
このように、初期軌道を更新していくことで、被研磨対象物の研磨作業を繰り返し行うことによって目標軌道が最適化され、研磨力の偏差を可及的に小さくすることができ、被研磨対象物の被研磨面をより一層高精度に研磨することができる。
【００６０】
特に、被研磨対象物の被研磨面に沿って移動する途中で研磨工具先端部の研磨面を変更させた場合には、研磨工具の先端部を全体にわたって研磨面として有効に活用することができ、これにより、研磨工具の長寿命化を図ることができる。
【図面の簡単な説明】
【図１】本発明に係る研磨装置の全体説明図。
【図２】研磨工具の拡大説明図。
【図３】研磨方法を示す説明図。
【符号の説明】
１研磨装置
２多関節ロボット
３アーム
４力覚センサ
５研磨工具
６アタッチメント
７支持体
８砥石
９被研磨対象物
10 被研磨面
11 研磨面
12 制御装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing apparatus and a polishing method.
[0002]
[Prior art]
Conventionally, when a mold is manufactured, automation using an NC processing apparatus or the like has been promoted.
[0003]
However, in the polishing process, which is a finishing process of mold manufacture, there is no polishing apparatus that polishes the mold surface with high accuracy, so that it has been performed manually by a skilled worker using a polishing tool.
[0004]
Therefore, in recent years, several polishing apparatuses that automatically perform the polishing process have been proposed.
[0005]
For example, in the polishing apparatus disclosed in Patent Document 1, a rotation drive mechanism is attached to the tip of an arm of an articulated robot, and a grindstone as a polishing tool is attached to the rotation drive mechanism, and the grindstone is rotated by the rotation drive mechanism. The polishing is performed by moving the grindstone along the surface to be polished of the object to be polished.
[0006]
Further, in the polishing apparatus disclosed in Patent Document 2, a rotation drive mechanism is attached to the machining center, and a grindstone as a polishing tool is attached to the rotation drive mechanism, and the object to be polished is rotated while the grindstone is rotated by the rotation drive mechanism. The polishing is performed by moving the grindstone along the surface to be polished.
[0007]
Further, in the polishing apparatus disclosed in Patent Document 3, a vibration plate as a polishing tool is attached to an ultrasonic vibrator, the vibration plate is brought into contact with a surface to be polished of an object to be polished, and the ultrasonic vibrator is used. Polishing is performed by vibrating the diaphragm.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-100754
[Patent Document 2]
JP-A-10-166267 [0010]
[Patent Document 3]
Japanese Patent Laid-Open No. 11-347894
[Problems to be solved by the invention]
However, even in the conventional polishing apparatus, the surface to be polished of the object to be polished cannot be polished with high accuracy.
[0012]
That is, in the above-described conventional polishing apparatus, polishing is performed by rotating or vibrating the polishing tool using a rotation drive mechanism or an ultrasonic vibrator, so that drive noise is generated at the same time when rotation or vibration occurs. As a result, the pressing force between the polishing surface of the polishing tool and the surface to be polished of the object to be polished cannot be accurately detected due to the influence of the driving noise, thereby increasing the position and posture of the polishing tool. It was not possible to control the accuracy.
[0013]
In addition, the grinding force due to rotation and vibration acts strongly, and it is difficult to finely adjust the polishing force acting on the surface to be polished during polishing.
[0014]
Also, not only polishing tools but also heavy objects such as rotary drive mechanisms and ultrasonic vibrators must be lifted by an articulated robot or machining center, which also finely adjusts the polishing force acting on the surface to be polished during polishing. It was difficult to do.
[0015]
As described above, the conventional polishing apparatus can roughly polish the surface of a mold or the like, but the polishing force acting on the surface to be polished at the time of polishing cannot be finely adjusted. It was not practical for finishing the mold.
[0016]
[Means for Solving the Problems]
Therefore, in the present invention according to claim 1, a polishing tool having a spherical polishing surface having a smaller radius of curvature than the radius of curvature of the surface to be polished of the object to be polished is attached to the tip of an arm that can be displaced and moved. By moving the polishing tool while maintaining the posture of the polishing tool, the polishing surface of the polishing tool is moved along the surface to be polished while being pressed against the surface to be polished in a point contact state. In addition, the feed path of the tip of the polishing tool is feedforward controlled along an initial track prepared in advance , the pressing force between the polishing surface of the polishing tool and the surface to be polished of the polishing tool, and the tip of the polishing tool moved by as resultant force of the motor friction and viscous friction force generated between the surface to be polished of the polishing surface and the polishing object in the polishing tool is a predetermined polishing force, to be polished and the polishing surface of the polishing tool Contact point of the object to be polished The normal speed and tangential speed of the polishing tool are determined by feedback control, and the initial trajectory of the polishing tool is appropriately determined by determining the amount of arm shift from these normal speed and tangential speed. When the polishing tool is moved while correcting, and the initial trajectory of the polishing tool is corrected, the actual trajectory through which the tip of the polishing tool actually passes is stored, and the previous actual trajectory is stored during the next polishing operation. A polishing apparatus for use as an initial trajectory is provided .
[0017]
Moreover, in this invention which concerns on Claim 2, it decided to change the grinding | polishing surface of a grinding | polishing tool front-end | tip part in the middle of moving along the grinding | polishing surface of a to-be-polished target object in the said 1st invention.
[0018]
According to the third aspect of the present invention, a polishing tool having a spherical polishing surface having a radius of curvature smaller than the radius of curvature of the surface to be polished of the object to be polished is in point contact with the surface to be polished of the object to be polished. And the polishing surface of the polishing tool is moved along the surface to be polished while maintaining the posture of the polishing tool, and is smaller than the radius of curvature of the surface to be polished of the object to be polished. A polishing tool having a spherical polishing surface with a radius of curvature is pressed in a point contact state against the surface to be polished of the object to be polished, and the polishing surface of the polishing tool is held on the object to be polished while maintaining the posture of the polishing tool. The tool is moved along the surface to be polished, and the track of the tip of the polishing tool is feedforward controlled along the initial track prepared in advance, and the pressing force between the tip of the polishing tool and the surface to be polished and the polishing are controlled. Polishing by moving the tool tip Resultant force of the motor friction and viscous friction force generated between the polishing surface and the polished surface of the object to be polished is a predetermined polishing force as possible, and the polished surface of the polished surface and the polishing object in the polishing tool The normal speed and tangential speed of the polishing tool at the contact point are determined by feedback control, and the initial trajectory of the polishing tool is appropriately modified from these normal speed and tangential speed. When the initial trajectory of the polishing tool is corrected, the actual trajectory through which the tip of the polishing tool actually passes is stored, and control is performed so that the previous actual trajectory is used as the initial trajectory during the next polishing operation. Decided to do.
[0019]
Moreover, in this invention which concerns on Claim 4, it decided to change the grinding | polishing surface of a grinding | polishing tool front-end | tip part in the middle of moving along the grinding | polishing surface of a to-be-polished target object in the said 3rd invention.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The polishing apparatus according to the present invention polishes the surface to be polished of a workpiece to be polished with a grindstone as a polishing tool attached to the tip of an arm of an articulated robot.
[0021]
Then, a polishing tool having a spherical polishing surface with a radius of curvature smaller than the curvature radius of the surface to be polished of the object to be polished is attached to the tip of the arm that can be displaced, and the arm maintains the posture of the polishing tool. By displacing, the polishing surface of the polishing tool is moved along the surface to be polished while being pressed against the surface to be polished in a point contact state. The resultant force of the kinetic frictional force and the viscous frictional force generated between the polishing surface of the polishing tool and the surface to be polished by the pressing force of the object to be polished with the surface to be polished and the movement of the tip of the polishing tool is predetermined. The amount of displacement of the arm is controlled so as to obtain a polishing force of 5 mm.
[0022]
Thus, in the polishing apparatus according to the present invention, the polishing tool is displaced while maintaining the attitude of the polishing tool, and the pressing force between the polishing surface of the polishing tool and the surface to be polished of the object to be polished and the movement of the tip of the polishing tool Thus, the resultant force of the kinetic friction force and the viscous friction force generated between the polishing surface of the polishing tool and the surface to be polished of the polishing object is applied to the surface to be polished as a polishing force.
[0023]
Therefore, unlike the conventional polishing apparatus, the polishing apparatus according to the present invention does not rotate or vibrate the polishing tool using the rotation drive mechanism or the ultrasonic vibrator, and thus drive noise is generated during the polishing operation. It is possible to accurately detect the pressing force between the polishing surface of the polishing tool and the polishing surface of the object to be polished, and thereby the position and posture of the polishing tool can be accurately detected. Can be controlled.
[0024]
Moreover, since the polishing tool is not rotated or vibrated, the polishing force can be suppressed to the minimum necessary, and the polishing force acting on the surface to be polished during polishing can be easily finely adjusted.
[0025]
Moreover, it is only necessary to lift a relatively lightweight polishing tool such as a grindstone with a shaft by an arm of an articulated robot, and this also makes it possible to easily fine-tune the polishing force acting on the surface to be polished during polishing. .
[0026]
In particular, when the polishing surface of the polishing tool tip is changed while moving along the surface to be polished, the tip of the polishing tool can be effectively used as a polishing surface throughout. As a result, the life of the polishing tool can be extended.
[0027]
As described above, in the polishing apparatus according to the present invention, the polishing force acting on the surface to be polished during polishing can be easily finely adjusted, so that the polishing apparatus is practically applied to finishing a mold having a complicated curved surface. be able to.
[0028]
The present invention is characterized by the structure of the polishing apparatus and also by a polishing method that is a control method thereof.
[0029]
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
[0030]
As shown in FIGS. 1 and 2, the polishing apparatus 1 according to the present invention attaches the upper surface of the force sensor 4 to the tip of the arm 3 of the articulated robot 2, and the polishing tool 5 on the lower surface of the force sensor 4. Is detachably attached via the attachment 6. In the figure, 12 is a control device for changing the position and posture of the arm 3 of the articulated robot 2.
[0031]
The articulated robot 2 only needs to be able to move the polishing tool 5 provided at the tip of the arm 3 by changing and controlling the position and posture of the arm 3. In this embodiment, the articulated robot 2 is an open architecture type. An industrial robot is used.
[0032]
The force sensor 4 uses a sensor having three degrees of freedom that can independently detect force values in the X, Y, and Z directions in the right-handed coordinate system.
[0033]
As shown in FIG. 2, the polishing tool 5 has a substantially cylindrical grindstone 8 provided continuously at the tip of a support 7 attached to the attachment 6.
[0034]
In addition, as shown in FIGS. 2 and 3, the tip of the polishing tool 5 (grinding stone 8) is polished in a hemispherical shape having a radius of curvature R smaller than the radius of curvature r of the surface to be polished 10 of the object 9 to be polished. It is surface 11.
[0035]
This is because the polishing surface 11 of the polishing tool 5 can be polished over the entire surface 10 of the object 9 to be polished. If the surface 10 to be polished 9 is a three-dimensional free-form surface and has irregularities, the radius of curvature R of the polishing surface 11 of the polishing tool 5 is taken into account in consideration of the radius of curvature r at the irregularities. To decide.
[0036]
The polishing apparatus 1 is configured as described above, and the surface to be polished of the object 9 to be polished by the polishing surface 11 of the polishing tool 5 by controlling the articulated robot 2 by the control device 12 as described below. Polish 10
[0037]
First, the control device 12 displaces the arm 3 of the articulated robot 2 while maintaining the posture of the polishing tool 5 so that the polishing surface 11 of the polishing tool 5 makes point contact with the surface 10 to be polished of the object 9 to be polished. It is pressed in the state (indicated by symbol (a) in FIG. 3). In this embodiment, the posture of the polishing tool 5 is a vertically downward posture (−Z direction). The posture of the polishing tool 5 is not particularly limited to a vertically downward posture, and may be any posture, as long as the polishing tool 5 can be displaced and moved by the arm 3 while maintaining the posture.
[0038]
Next, the control device 12 displaces the arm 3 of the articulated robot 2 while maintaining the posture of the polishing tool 5, thereby moving the polishing surface 11 of the polishing tool 5 along the surface to be polished 10 of the object 9 to be polished. (Indicated by symbols (b), (c), (d), and (e) in FIG. 3).
[0039]
Here, when the polishing tool 5 is displaced and moved by the arm 3 of the articulated robot 2, the control device 12 makes the polishing surface 11 of the polishing tool 5 point-contact with the polishing target surface 10 of the polishing target 9. The displacement is moved while holding.
[0040]
Moreover, the control device 12 polishes the polishing tool 5 by the pressing force f between the polishing surface 11 of the polishing tool 5 and the surface 11 to be polished 9 and the movement of the tip (polishing surface 11) of the polishing tool 5. The amount of displacement of the arm 3 is controlled so that the resultant force F of the kinetic frictional force fd and the viscous frictional force fs generated between the surface 11 and the surface 10 to be polished 9 becomes a predetermined polishing force Fd. I am doing so.
[0041]
Here, the pressing force f between the polishing surface 11 of the polishing tool 5 and the polishing target surface 11 of the object 9 to be polished is the fx, fy, fz respectively in the X, Y, Z directions in the right-handed coordinate system. Then, the pressing force f (fx, fy, fz) is expressed, and the normal direction velocity Vn of the polishing tool 5 at the contact point between the polishing surface 11 of the polishing tool 5 and the surface to be polished 10 of the object 9 to be polished is expressed. Vnx, Vny, Vnz).
[0042]
Further, the kinetic frictional force fd generated by the movement of the tip portion (polishing surface 11) of the polishing tool 5 has a kinetic friction coefficient μ, and the polishing surface 11 of the polishing tool 5 and the surface 10 to be polished 9 When the tangential speed of the polishing tool 5 at the contact point is Vt (Vtx, Vty, Vtz), it is expressed as fd = −μ · | f | · (Vt / | Vt |), the coefficient of motion friction μ and the polishing tool The tangential speed Vt (Vtx, Vty, Vtz) of the polishing tool 5 at the contact point between the polishing surface 11 of 5 and the surface 10 of the object 9 to be polished.
[0043]
Further, the viscous frictional force fs generated between the polishing surface 11 of the polishing tool 5 and the surface 10 to be polished 9 is expressed as fs = −η · Vt, where the coefficient of viscous friction is η, It is given by the viscous friction coefficient η and the tangential velocity Vt (Vtx, Vty, Vtz) of the polishing tool 5 at the contact point between the polishing surface 11 of the polishing tool 5 and the surface 10 to be polished 9.
[0044]
Therefore, the control device 12 has a resultant force F (F = f + fd + fs = f−μ · | f | · (Vt / | Vt |) −η · Vt) of the pressing force f, the kinetic frictional force fd, and the viscous frictional force fs. The normal velocity Vn and the tangent of the polishing tool 5 at the contact point between the polishing surface 11 of the polishing tool 5 and the surface 10 to be polished 9 so as to be equal to a predetermined polishing force set in advance. The direction speed Vt is determined by feedback control, and the displacement amount of the arm 3 is determined from the normal direction speed Vn and the tangential direction speed Vt.
[0045]
A known control method can be used for the force control of the arm 3 of the articulated robot 2 (see, for example, Japanese Patent Application No. 10-173509 and Japanese Patent Application No. 11-241771).
[0046]
Then, the control device 12 moves the polishing tool 5 while appropriately correcting the initial trajectory T ¹ (T ¹ x (j), T ¹ y (j), T ¹ z (j)) prepared in advance. . Here, j = 1, 2, 3... K (k is a positive integer), and the initial trajectory T ¹ is composed of vectors of k rows.
[0047]
As a result, the polishing surface 11 of the polishing tool 5 moves while making point contact with the surface to be polished 10 of the object 9 to be polished, and the surface 10 to be polished of the object 9 to be polished is polished by the polishing surface 11 of the polishing tool 5. The Here, the initial trajectory T ¹ takes into consideration that the tip of the polishing tool 5 is a hemispherical surface having a radius R, and the polishing surface 11 of the polishing tool 5 makes point contact with the surface to be polished 10 of the object 9 to be polished. However, the trajectory is set at the center position of the tip of the polishing tool 5 that is offset so that it can be moved.
[0048]
That is, the control device 12 feedforward-controls the trajectory of the tip portion of the polishing tool 5 along the initial trajectory T ¹ and, as described above, the resultant force of the pressing force f, the kinetic friction force fd, and the viscous friction force fs. The normal velocity Vn and the tangential velocity Vt are determined by feedback control so that F becomes a predetermined polishing force Fd, and the displacement amount of the arm 3 is determined from these normal velocity Vn and tangential velocity Vt. Thus, the initial trajectory T ¹ is corrected accordingly.
[0049]
At this time, the controller 12, the track with modifications to the initial trajectory T ^1, that is, the actual trajectory which the tip of the polishing tool 5 is actually passes ^{^{T n (T n x (j}} ), T n y ( j), T ⁿ z (j)) (where, n represents indicates the number of times.) is stored as to be able to use a real trajectory T ⁿ last at the next polishing operation as the initial target track ing.
[0050]
In this way, by updating the initial target trajectory, the target trajectory is optimized by repeating the polishing operation of the object 9 to be polished, and the deviation of the polishing force F can be made as small as possible. In addition, the surface to be polished 10 of the object to be polished 9 can be polished with higher accuracy.
[0051]
In the present embodiment, the control device 12 changes the polishing surface 11 at the tip of the polishing tool 5 while moving the polishing surface 11 of the polishing tool 5 along the surface 10 to be polished 9. I try to let them.
[0052]
That is, the control device 12 polishes the tip of the arm 3 while rotating the tip of the arm 3 within a range in which a frictional force due to rotational motion does not act between the polishing surface 11 of the polishing tool 5 and the surface 10 of the object 9 to be polished. The polishing surface 11 of the tool 5 is moved along the surface 10 to be polished of the object 9 to be polished. Note that the polishing surface 11 of the polishing tool 5 may be changed by rotating the polishing tool 5 continuously at a very low speed, or by rotating the polishing tool 5 intermittently at a very low speed at a predetermined location. May be.
[0053]
In this way, by changing the polishing surface 11 of the polishing tool 5, the tip of the polishing tool 5 can be effectively used as the polishing surface 11 throughout, thereby extending the life of the polishing tool 5. be able to.
[0054]
【The invention's effect】
The present invention is implemented in the form described above, and has the following effects.
[0055]
That is, in the present invention, the polishing tool is displaced while maintaining the posture of the polishing tool, and the polishing surface of the polishing tool is moved by the pressing force between the polishing surface of the polishing tool and the polishing surface of the object to be polished and the movement of the tip of the polishing tool. The resultant force of the kinetic friction force and the viscous friction force generated between the surface of the object to be polished and the surface of the object to be polished acts on the surface to be polished as a polishing force.
[0056]
Therefore, unlike a conventional polishing apparatus, the polishing tool is not rotated or vibrated using a rotation drive mechanism or an ultrasonic vibrator, so that it is possible to prevent drive noise from being generated during polishing work. The polishing force between the polishing surface of the polishing tool and the polishing surface of the object to be polished can be detected with high accuracy, and the position and posture of the polishing tool can be controlled with high accuracy.
[0057]
Moreover, since the polishing tool is not rotated or vibrated, the polishing force can be suppressed to the minimum necessary, and the polishing force acting on the surface to be polished during polishing can be easily finely adjusted.
[0058]
Further, it is only necessary to lift a relatively lightweight polishing tool with the arm of the articulated robot, and this also makes it possible to easily finely adjust the polishing force acting on the surface to be polished during polishing.
[0059]
As described above, in the present invention, the polishing force acting on the surface to be polished during polishing can be easily fine-tuned, whereby the surface to be polished of the object to be polished can be accurately polished.
Further, in the present invention, the feed path of the tip of the polishing tool is feedforward controlled along an initial track prepared in advance, and the pressing force between the polishing surface of the polishing tool and the surface to be polished is as the resultant force of the motor friction and viscous friction force generated between the surface to be polished of the polishing surface and the polishing object in the polishing tool by movement of the polishing tool tip has a predetermined polishing power, the polishing of the polishing tool The normal speed and tangential speed of the polishing tool at the contact point between the surface and the surface of the object to be polished are determined by feedback control, and the arm transition is determined from these normal speed and tangential speed. By determining the amount, the polishing tool is moved while properly correcting the initial trajectory of the polishing tool, and when the initial trajectory of the polishing tool is corrected, the actual trajectory through which the tip of the polishing tool actually passes is stored. Please , And to use a real trajectory preceding the next time the polishing operation as the initial trajectory.
In this way, by updating the initial trajectory, the target trajectory is optimized by repeating the polishing operation of the object to be polished, and the deviation of the polishing force can be made as small as possible. The surface to be polished of the object can be polished with higher accuracy.
[0060]
In particular, when the polishing surface of the polishing tool tip is changed while moving along the surface to be polished, the tip of the polishing tool can be effectively used as a polishing surface throughout. As a result, the life of the polishing tool can be extended.
[Brief description of the drawings]
FIG. 1 is an overall explanatory view of a polishing apparatus according to the present invention.
FIG. 2 is an enlarged explanatory view of a polishing tool.
FIG. 3 is an explanatory view showing a polishing method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Polishing apparatus 2 Articulated robot 3 Arm 4 Force sensor 5 Polishing tool 6 Attachment 7 Support body 8 Grinding stone 9 Object to be polished
10 Surface to be polished
11 Polished surface
12 Control unit

Claims

A polishing tool having a spherical polishing surface with a radius of curvature smaller than the radius of curvature of the surface to be polished of the object to be polished is attached to the tip of a displaceable arm, and the arm is displaced while maintaining the posture of the polishing tool. By moving the polishing surface of the polishing object along the surface to be polished while pressing the polishing surface of the polishing object in a point contact state with the polishing surface,
Moreover, while performing feedforward control along the initial trajectory prepared in advance, the trajectory of the tip of the polishing tool,
Kinematic friction force and viscosity generated between the polishing surface of the polishing tool and the surface to be polished by the pressing force between the polishing surface of the polishing tool and the surface to be polished and the movement of the tip of the polishing tool Feedback control is used to control the normal speed and tangential speed of the polishing tool at the contact point between the polishing surface of the polishing tool and the polishing surface of the object to be polished so that the resultant force with the frictional force becomes a predetermined polishing force . While determining, by determining the amount of arm movement from these normal direction velocity and tangential direction velocity, the polishing tool is moved while appropriately correcting the initial trajectory of the polishing tool,
Furthermore, when correcting the initial trajectory of the polishing tool, the actual trajectory through which the tip of the polishing tool actually passes is stored, and the previous actual trajectory is used as the initial trajectory during the next polishing operation. Polishing equipment.

The polishing apparatus according to claim 1, wherein the polishing surface of the tip of the polishing tool is changed during the movement along the surface to be polished of the object to be polished.

A polishing tool having a spherical polishing surface with a radius of curvature smaller than the radius of curvature of the surface to be polished of the object to be polished is pressed against the surface to be polished of the object to be polished in a point contact state, and the posture of the polishing tool is changed. Move the polishing surface of the polishing tool along the surface to be polished while holding it,
Moreover, while performing feedforward control along the initial trajectory prepared in advance, the trajectory of the tip of the polishing tool,
The resultant force of the kinetic friction force and the viscous friction force generated between the polishing surface of the polishing tool and the surface to be polished of the object to be polished by the pressing force between the polishing tool tip and the surface to be polished and the movement of the tip of the polishing tool is The normal speed and tangential speed of the polishing tool at the contact point between the polishing surface of the polishing tool and the surface to be polished of the object to be polished are determined by feedback control to achieve a predetermined polishing force, and these normals From the directional speed and the tangential speed, move the polishing tool while appropriately modifying the initial trajectory of the polishing tool,
Furthermore, when correcting the initial trajectory of the polishing tool, the actual trajectory through which the tip of the polishing tool actually passes is stored, and control is performed so that the previous actual trajectory is used as the initial trajectory during the next polishing operation. A characteristic polishing method.

4. The polishing method according to claim 3, wherein the polishing surface of the tip of the polishing tool is changed during the movement along the surface to be polished of the object to be polished.