JP4175782B2

JP4175782B2 - Polishing method

Info

Publication number: JP4175782B2
Application number: JP2001064562A
Authority: JP
Inventors: 軍張; 英利寒河江; 弘之遠藤; 憲一市川
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2001-03-08
Filing date: 2001-03-08
Publication date: 2008-11-05
Anticipated expiration: 2021-03-08
Also published as: JP2002263996A

Description

【０００１】
【発明の属する技術分野】
本発明は、研磨方法、研磨工具及び光学部品に関し、詳細には、うねりを適切に除去して高精度に研磨する研磨方法に関する。
【０００２】
【従来の技術】
力制御研磨はレンズ、鏡、成形金型などの超精密仕上げの加工方法として幅広く用いられており、力制御研磨では、研磨除去量を精密に制御することができるとともに、球面、非球面、自由曲面形状においても、形状にならい、当該形状を崩すことなく、均一に研磨することもできるようになってきている。
【０００３】
一方、近年、複写機、レーザプリンタのレーザ走査の高密度化、カラー化の進行に伴い、レーザ走査のビーム径はますます小さくなってきており、レーザ走査の光学系に使用されるレンズやこのレンズを成形する金型においても、ただ精度の良い表面粗さでは不十分となり、小さい振幅、長い波長を有するうねりを極力に抑えることも要求されるようになってきている。
【０００４】
そして、従来、高精度の非球面を製作する研磨方法として、加工面を研磨するための研磨方法において、加工面形状と設計面形状との形状誤差を部分的に修正する部分修正研磨を前記加工面に施すステップと接触面積及び硬さが異なるポリシャを多段階に使い分け、部分修正研磨を施された前記加工面のうねりを除去するステップとを有する研磨方法が提案されている（特開平９−２４８７４１号公報参照）。
【０００５】
すなわち、この研磨方法は、加工面形状と設計面形状との形状誤差を部分的に修正し、接触面積及び硬さが異なるポリシャを多段階に使い分けて、うねりを除去しようとしている。
【０００６】
また、従来、被加工物の加工面上を滑動させながら加工を行う研磨工具において、前記加工面の除去したいうねり周期の２倍以上の径を有するポリシャを、前記研磨工具のツ―ルに３個以上設けると共に、前記各ポリシャを独立に傾斜可能に設けた研磨工具が提案されている（特開平９-３２３２４９号公報参照）。
【０００７】
すなわち、この技術は、研磨工具を加工物の加工面上に滑動させながら研磨を行い、研磨工具に除去したいうねり周期の２倍以上の径を有するポリシャを３個以上設け、そして各ポリシャを独立に傾斜可能にすることによって、うねりを除去しようとしている。
【０００８】
【発明が解決しようとする課題】
しかしながら、このような従来の技術にあっては、うねりの低減まで要求される高精度な加工を必要とする光学素子成形用金型の加工に対しては、不十分であり、さらなる高精度な加工技術が要求される。
【０００９】
すなわち、特開平9-２４８７４１号公報記載の技術にあっては、加工面形状と設計面形状との形状誤差を修正すると同時に、接触面積及び硬さの異なるポリシャで、加工面の微小なうねりを除去しようとしているため、小さい振幅、長い波長を有するうねりを除去することができないという問題があった。
【００１０】
また、特開平９-３２３２４９号公報記載の技術にあっては、研磨ツールに除去したいうねり周期の２倍以上の径を有するポリシャを３個以上設けるとともに、各ポリシャを独立に傾斜可能にして、うねり除去しようとしているため、レンズ全体の寸法が小さく、うねりの波長がレンズ全体形状の半分よりも長い場合には、うねりを除去することができず、特に、曲率が逆転する自由曲面の場合には、このような工具形状では、うねりを除去することができないという問題があった。
【００１１】
そこで、本発明は、２点接触研磨によって、うねりにならわずに、加工面形状にならい、研磨押し付け力を両接触点（面）間に移動することで、加工面形状を崩すことなく、振幅が小さく、工具接触幅よりも長い波長を有するうねりを除去する研磨方法を提供することを目的としている。
【００１２】
具体的には、請求項１記載の発明は、回転する全体が曲がらない研磨工具を研磨押し付け力で被加工物の加工面に押し付けながら該被加工物の加工面上の形状にならって該研磨押し付け力を一定に制御しつつ走査して研磨加工を行い、前記研磨工具が前記加工面上に２ヶ所の研磨接触点を有する研磨方法において、前記研磨工具の回転軸と、前記２ヶ所の研磨接触点を結ぶ直線とを、前記研磨工具のトラバース方向に平行とすることにより、振幅が小さく、研磨工具の接触幅よりも長い波長を有するうねりを、研磨工具や研磨ツールを大型化することなく、確実にかつ効率的に除去できるとともに、加工面の形状を崩すことなく、研磨加工方向に沿ってうねりを除去し、確実かつ効率的に振幅が小さく、研磨工具の接触幅よりも長い波長を有するうねりを除去することのできる研磨方法を提供することを目的としている。
【００１３】
請求項２記載の発明は、回転する全体が曲がらない研磨工具を研磨押し付け力で被加工物の加工面に押し付けながら該被加工物の加工面上の形状にならって該研磨押し付け力を一定に制御しつつ走査して研磨加工を行い、前記研磨工具が前記加工面上に２ヶ所の研磨接触点を有する研磨方法において、前記研磨工具の回転軸と、前記２ヶ所の研磨接触点を結ぶ直線とを、前記研磨工具のトラバース方向に平行とするとともに、加工面にうねりが存在しない場所では、研磨押し付け力は前記２ヶ所の研磨接触点で平均化されるが、研磨加工具のトラバースに伴い、前記加工面上に存在するうねりの山の部分に接触する研磨加工方向先頭側の研磨接触点に前記研磨押し付け力が集中することにより、一回のトラバースでうねりの山に対して２回接触して研磨加工して、うねりの除去をより確実にかつ効率的に行うとともに、２ヶ所の研磨接触点（面）での研磨押し付け力を分配して、荒加工と仕上げ加工を同時に行うことのできる研磨方法を提供することを目的としている。
【００２０】
【課題を解決するための手段】
請求項１記載の発明の研磨方法は、回転する全体が曲がらない研磨工具を研磨押し付け力で被加工物の加工面に押し付けながら該被加工物の加工面上の形状にならって該研磨押し付け力を一定に制御しつつ走査して研磨加工を行い、前記研磨工具が前記加工面上に２ヶ所の研磨接触点を有する研磨方法において、前記研磨工具の回転軸と、前記２ヶ所の研磨接触点を結ぶ直線とを、前記研磨工具のトラバース方向に平行とすることにより、上記目的を達成している。
【００２１】
上記構成によれば、回転する全体が曲がらない研磨工具を研磨押し付け力で被加工物の加工面に押し付けながら該被加工物の加工面上の形状にならって該研磨押し付け力を一定に制御しつつ走査して研磨加工を行うに際して、研磨工具が前記加工面上に２ヶ所の研磨接触点を有するとともに、研磨工具の回転軸と、前記２ヶ所の研磨接触点を結ぶ直線とが、前記研磨工具のトラバース方向に平行となっているので、振幅が小さく、研磨工具の接触幅よりも長い波長を有するうねりを、研磨工具や研磨ツールを大型化することなく、確実にかつ効率的に除去することができる。
【００２３】
また、研磨工具の２箇所の研磨接触点を結ぶ直線を研磨加工のトラバース方向に平行にしているので、加工面の形状を崩すことなく、研磨加工方向に沿ってうねりを除去することができ、確実かつ効率的に振幅が小さく、研磨工具の接触幅よりも長い波長を有するうねりを除去することができる。
【００２４】
請求項２記載の発明の研磨方法のように、回転する全体が曲がらない研磨工具を研磨押し付け力で被加工物の加工面に押し付けながら該被加工物の加工面上の形状にならって該研磨押し付け力を一定に制御しつつ走査して研磨加工を行い、前記研磨工具が前記加工面上に２ヶ所の研磨接触点を有する研磨方法において、前記研磨工具の回転軸と、前記２ヶ所の研磨接触点を結ぶ直線とを、前記研磨工具のトラバース方向に平行とするとともに、加工面にうねりが存在しない場所では、研磨押し付け力は前記２ヶ所の研磨接触点で平均化されるが、研磨加工具のトラバースに伴い、前記加工面上に存在するうねりの山の部分に接触する研磨加工方向先頭側の研磨接触点に前記研磨押し付け力が集中するようにしてもよい。
【００２５】
上記構成によれば、加工面にうねりが存在しない場所では、研磨押し付け力は前記２ヶ所の研磨接触点で平均化されるが、研磨加工具のトラバースに伴い、前記加工面上に存在するうねりの山の部分に接触する研磨加工方向先頭側の研磨接触点に前記研磨押し付け力が集中するので、一回のトラバースでうねりの山に対して２回接触して研磨加工して、うねりの除去をより確実にかつ効率的に行うことができるとともに、２ヶ所の研磨接触点（面）での研磨押し付け力を分配して、荒加工と仕上げ加工を同時に行うことができる。
【００３６】
【発明の実施の形態】
以下、本発明の好適な実施の形態を添付図面に基づいて詳細に説明する。なお、以下に述べる実施の形態は、本発明の好適な実施の形態であるから、技術的に好ましい種々の限定が付されているが、本発明の範囲は、以下の説明において特に本発明を限定する旨の記載がない限り、これらの態様に限られるものではない。
【００３７】
図１〜図５は、本発明の研磨方法、研磨工具及び光学部品の第１の実施の形態を示す図であり、図１は、本発明の研磨方法、研磨工具及び光学部品の第１の実施の形態を適用した研磨方法に使用する研磨工具の正面図である。
【００３８】
図１において、研磨工具１は、同じ大きさの球状の研磨部２と研磨部３が、シャフト４で連結されており、シャフト４は、球状の研磨部２中心軸２ａと研磨部３の中心軸３ａを連結している。研磨工具１は、研磨部２と研磨部３がそれぞれ被加工物の加工面に接触して研磨を行い、被加工物の加工面に対して、研磨部２と研磨部３という２カ所の研磨接触点（面）を有している。
【００３９】
研磨工具１は、加工面に押し付けられた際、図２に示すように、その研磨部２と研磨部３の被加工物の加工面に対する２ヶ所の研磨接触点（面）の間隔をｄとすると、間隔ｄが、次式のヘルツの式を満足する状態で、研磨部２と研磨部３がシャフト４で連結されている。
【００４０】
【数２】

なお、ａは、研磨工具１が加工面に押付けられたときの最大接触円半径、Ｆは、工具押し付け力、Ｒ_A は、工具曲率半径、Ｅ_A は、工具の縦弾性係数、ν_A は、工具のポアソン比、Ｒ_B は、被加工物の加工面の曲率半径、Ｅ_B は、被加工物の縦弾性係数、 ν_B は、被加工物のポアソン比である。
【００４１】
すなわち、図２で示しているように、押し付け力Ｆによる研磨部２と研磨部３による２ヶ所の研磨接触点（面）での最大接触円半径の和は、この２ヶ所の研磨接触点（面）の間隔ｄよりも小さく、研磨工具１は、その弾性変形が２ヶ所の研磨接触点（面）を一体化させない材料で形成されている。特に、研磨工具１は、そのシャフト４が、弾性変形の極めて小さい超硬合金やセラミックスで形成されている。
【００４２】
次に、本実施の形態の作用を説明する。上記研磨工具１を用いて加工面として平面を有する被加工物を研磨する場合、以下の手順で行う。
【００４３】
すなわち、図３に示すように、研磨工具１を被加工物１０の加工面１１上に２ヶ所の研磨点（面）を持たせながら、加工面１１上の形状をならい、押し付け力Ｐを一定にして研磨加工を行う。平面の被加工物１０の研磨加工においては、スタート時の研磨工具１と被加工物１０の加工面１１の力の釣り合いは、図３に示すように、次式（２）、次式（３）を満足する。
【００４４】
Ｎ₁＝Ｐ₁＝（１／２）×Ｐ＝（１／２）×Ｎ・・・（２）
Ｎ₂＝Ｐ₂＝（１／２）×Ｐ＝（１／２）×Ｎ・・・（３）
ここで、Ｐ₁、Ｐ₂は、研磨部２、研磨部３の押し付け力、Ｎ₁、Ｎ₂は、その反発力である。
【００４５】
上記状態で、加工を開始すると、研磨部２と研磨部３の両接触点（面）の間には、図４に示すように、未除去の部分が高くなり、見かけ上「山」として現れる。
【００４６】
そして、研磨方向は、図３及び図４に加工方向として矢印で示す図３及び図４の右方向であり、右方向への研磨加工が進行するに伴って、この研磨部２と研磨部３の間の山の部分は、図５に示すように、左側の研磨部２によって除去されて、再び、研磨工具１の研磨部２と研磨部３の両接触点（面）が同一水平面になる。
【００４７】
そして、この状態で、右方向に研磨が進むと、図５に示すように、加工方向先端側の研磨部３のみが被加工物１０の未加工の加工面１１の加工を開始する状態となって、上記式（２）と式（３）の関係式が成り立たなくなり、図６に示すように、次式（４）〜次式（７）の新たな力釣り合いの関係式を満足することになる。
【００４８】
Ｎ₁₁＝Ｐ₁₁・・・（４）
Ｎ₂₂＝Ｐ₂₂・・・（５）
Ｎ₂₃＝Ｐ₂₂・cosθ・・・（６）
Ｎ₁₁＋Ｎ₂₂＝Ｎ＝Ｐ・・・（７）
いま、研磨工具１、特に、シャフト４は、弾性変形のきわめて小さい材料で形成されており、研磨工具１全体が曲がらないため、研磨工具１がさらに右方向に進行すると、結局、図７に示すように、研磨の押し付け力Ｐは、完全に右側の研磨部３の接触点（面）に移ることになる。図７において、研磨工具１による研磨除去量が小さいため、研磨が行われている加工面１１と未研磨の加工面１１とのなす角度θは小さく、０に近く、cosθ＞１／２となるため、上記式（６）は、次式（８）で表される。
【００４９】
Ｎ₂₃＝Ｐcosθ＞Ｎ₂＝（１／２）×Ｐ・・・（８）
そして、被加工物１０の加工面１１、すなわち、ワーク表面が完全な平面である場合には、上記（８）式が常に成り立ち、往復研磨加工を行うと、研磨押し付け力Ｐは、左右の研磨部２と研磨部３の２ヶ所の研磨接触点（面）で繰り返し交替し、被加工物１０の加工面１１を左右の接触点（面）の交替で研磨加工することがでる。
【００５０】
また、研磨押し付け力Ｐと弾性係数が異なる工具材料（研磨工具１全体は同一材料）を選定すると、研磨押し付け力Ｐを完全に一つの研磨接触点（面）に移さないで、２ヶ所の研磨接触点（面）に一定な割合で分配することができる。
【００５１】
したがって、研磨進行方向に対して、前の接触点（面）で荒加工を行い、後の接触点（面）で仕上げ加工を同時に行うこともできる。
【００５２】
被加工物１０の加工面１１が、図示しないが、球面、非球面、自由曲面である場合には、このような球面、非球面、自由曲面にあるうねりを除去する研磨加工においては、加工面の形状に合わせて、研磨の押し付け力を一定に制御し、研磨工具１を小径化かつ２ヶ所の接触点（面）間の距離を短くすることによって、研磨工具１が被加工物の加工面上の形状をならうが、うねりにはならわない。
【００５３】
したがって、被加工物の加工面にある形状を崩すことなく、形状にあるうねりだけを、２研磨接触点（面）での研磨押し付け力の移動で除去することができる。
【００５４】
図８及び図９は、本発明の研磨方法、研磨工具及び光学部品の第２の実施の形態を示す図である。
【００５５】
なお、本実施の形態は、上記第１の実施の形態の研磨工具１と同様の研磨工具を用いて研磨を行っており、本実施の形態の説明においては、上記第１の実施の形態で用いた符号をそのまま用いて説明する。
【００５６】
図８は、研磨工具１が被加工物１０の平らな加工面１１にある小さい振幅で、研磨工具１の接触幅よりも長い波長を有するうねり２０の山を登るときの力釣り合いを示している。
【００５７】
この場合、うねり２０の振幅が小さく、かつ、波長が長いため、加工面１１とうねり２０の面とのなす角度θは、第１の実施の形態の場合よりは少し大きくなるが、やはり、０に近く、 cosθ＞１／２の関係は、崩れない。したがって、上記関係式（８）は、そのまま成り立つ。
【００５８】
そして、研磨工具１による研磨加工が右方向に進行するに伴って、右側の研磨部３の研磨接触点がうねり２０の山を越えると、図９に示すように、段々と研磨の押し付け力Ｐは、左側の研磨部２の接触点（面）に移ることになり、このときの力の釣り合いは、図９に示すように、次式（９）を満足する。
【００５９】
Ｎ₁₃＝Ｐcosθ＞Ｎ₁＝（１／２）×Ｐ・・・（９）
したがって、１回のトラバース研磨加工で、研磨工具１は、１つのうねり２０の山に対して２回も接触することができ、より確実にかつ効率的に研磨工具１の接触幅よりも波長が長く、かつ、振幅の小さいうねり２０を除去することができる。
【００６０】
上記研磨工具１により光学部品成形用金型を研磨加工すると、加工面形状を崩すことなく、振幅の小さく、かつ、研磨工具１の接触幅よりも長い波長を有するうねりを除去して、簡単かつ効率的に、また、より高精度に光学部品成形用金型を研磨加工することができる。
【００６１】
そして、この光学部品成形用金型を使用して、光学部品を成形すると、形状精度の優れた光学部品を得ることができる。
【００６２】
なお、上記各実施の形態において、研磨工具１としては、上記形状のものに限るものではなく、例えば、図１０に示すように、研磨工具３０は、球状の研磨部３１、３２が、所定の接触面を共有する状態で連結されており、研磨部３１と研磨部３２の中心を中心軸３３が貫通しているものであってもよい。
【００６３】
この研磨工具３０の場合には、上記研磨工具１と同様に、研磨部３１及び研磨部３２と被加工物の加工面との接触点が研磨接触点（面）となって、２箇所の研磨接触点（面）を有することになる。なお、この研磨工具３０は、図示しないが、中心軸３３に研磨工具を回転させるシャフトが連結される。
【００６４】
また、図１１に示すように、研磨工具４０は、１個の大きな球状の研磨部４１の中心を中心軸４２が貫通しており、この中心軸４２の周方向に、所定幅ｗを有し、所定深さｈの溝４３が形成されている。中心軸４２には、シャフト４４が連結されており、研磨工具４０は、中心軸４２を中心に回転駆動される。
【００６５】
この研磨工具４０は、図１２に示すように、溝４３を挟んで研磨部４１が被加工物の加工面との接触点が研磨接触点（面）となって、２箇所の研磨接触点（面）を有することとなり、この場合の研磨接触点（面）の間隔ｄは、上記ヘルツの式を満足する状態に、溝４３の幅ｗと深さｈが設定されている。
【００６６】
以上、本発明者によってなされた発明を好適な実施の形態に基づき具体的に説明したが、本発明は上記のものに限定されるものではなく、その要旨を逸脱しない範囲で種々変更可能であることはいうまでもない。
【００６７】
【発明の効果】
請求項１記載の発明の研磨方法によれば、回転する全体が曲がらない研磨工具を研磨押し付け力で被加工物の加工面に押し付けながら該被加工物の加工面上の形状にならって該研磨押し付け力を一定に制御しつつ走査して研磨加工を行うに際して、研磨工具が前記加工面上に２ヶ所の研磨接触点を有するとともに、研磨工具の回転軸と、前記２ヶ所の研磨接触点を結ぶ直線とが、前記研磨工具のトラバース方向に平行となっているので、振幅が小さく、研磨工具の接触幅よりも長い波長を有するうねりを、研磨工具や研磨ツールを大型化することなく、確実にかつ効率的に除去することができる。
【００６８】
また、加工面の形状を崩すことなく、研磨加工方向に沿ってうねりを除去することができ、確実かつ効率的に振幅が小さく、研磨工具の接触幅よりも長い波長を有するうねりを除去することができる。
【００６９】
請求項２記載の発明の研磨方法によれば、加工面にうねりが存在しない場所では、研磨押し付け力は前記２ヶ所の研磨接触点で平均化されるが、研磨加工具のトラバースに伴い、前記加工面上に存在するうねりの山の部分に接触する研磨加工方向先頭側の研磨接触点に前記研磨押し付け力が集中するので、一回のトラバースでうねりの山に対して２回接触して研磨加工して、うねりの除去をより確実にかつ効率的に行うことができるとともに、２ヶ所の研磨接触点（面）での研磨押し付け力を分配して、荒加工と仕上げ加工を同時に行うことができる。
【図面の簡単な説明】
【図１】本発明の研磨方法、研磨工具及び光学部品の第１の実施の形態に適用される研磨工具の正面図。
【図２】図１の研磨工具を研磨押し付け力で被加工物の加工面に押し付けた際の工具変形状態と接触点間隔を示す図。
【図３】図１の研磨工具で平面加工面の加工を開始した際の斜視図。
【図４】図３の研磨工具で研磨を行っている状態の正面図。
【図５】図４の研磨工具での研磨がさらに進行した状態の正面図。
【図６】図５の状態の研磨工具と加工面に作用する力釣り合い関係を示す図。
【図７】図６の研磨加工方向先頭側の研磨接触点での力釣り合い関係を示す図。
【図８】本発明の研磨方法、研磨工具及び光学部品の第２の実施の形態に適用される研磨工具で接触点間隔よりもの長いうねりを有する加工面を研磨加工している状態の正面図。
【図９】図８のうねりを超えて研磨加工方向後方側の研磨点で研磨を行っている状態の正面図。
【図１０】研磨工具の他の例を示す正面図。
【図１１】研磨工具のさらに他の例を示す正面図。
【図１２】図１１の研磨工具を研磨押し付け力で被加工物の加工面に押し付けた際の工具変形状態と接触点間隔を示す図。
【符号の説明】
１研磨工具
２、３研磨部
２ａ、３ａ中心軸
４シャフト
１０被加工物
１１加工面
２０うねり
３０研磨工具
３１、３２研磨部
３３中心軸
４０研磨工具
４１研磨部
４２中心軸
４３溝
４４シャフト[0001]
BACKGROUND OF THE INVENTION
The present invention is a polishing method, a polishing tool and the optical component, in particular, relates to a polishing how to polish properly remove waviness with high accuracy.
[0002]
[Prior art]
Force-controlled polishing is widely used as a processing method for ultra-precision finishing of lenses, mirrors, molding dies, etc. In force-controlled polishing, the amount of polishing removal can be precisely controlled, and spherical, aspherical, free Even in the curved surface shape, it has become possible to perform uniform polishing without breaking the shape following the shape.
[0003]
On the other hand, in recent years, with the progress of high density and colorization of laser scanning in copiers and laser printers, the beam diameter of laser scanning has become smaller and smaller. Even in a mold for molding a lens, an accurate surface roughness is insufficient, and it is required to suppress undulations having a small amplitude and a long wavelength as much as possible.
[0004]
Conventionally, as a polishing method for producing a highly accurate aspheric surface, in the polishing method for polishing a processed surface, partial correction polishing for partially correcting the shape error between the processed surface shape and the design surface shape is performed. There has been proposed a polishing method having a step of applying to a surface and a step of removing undulations of the processed surface subjected to partial correction polishing by using different polishers having different contact areas and hardnesses in multiple stages (Japanese Patent Laid-Open No. Hei 9- No. 248741).
[0005]
That is, this polishing method partially corrects the shape error between the processed surface shape and the design surface shape, and uses the polishers having different contact areas and hardnesses in multiple stages to remove the undulation.
[0006]
Further, conventionally, in a polishing tool that performs processing while sliding on a processing surface of a workpiece, a polisher having a diameter of twice or more of the wobbling period removed from the processing surface is applied to the tool of the polishing tool. There has been proposed a polishing tool provided with at least one and each of the polishers provided so as to be capable of being inclined independently (see JP-A-9-323249).
[0007]
That is, in this technique, polishing is performed while sliding the polishing tool on the work surface of the workpiece, and three or more polishers having a diameter of twice or more of the sag cycle removed are provided on the polishing tool, and each polisher is independently provided. Trying to remove the swell by making it tiltable.
[0008]
[Problems to be solved by the invention]
However, such a conventional technique is insufficient for processing an optical element molding die that requires high-precision processing required to reduce waviness, and provides further high-precision. Processing technology is required.
[0009]
That is, in the technique described in Japanese Patent Laid-Open No. 9-248741, the shape error between the machined surface shape and the design surface shape is corrected, and at the same time, minute waviness of the machined surface is caused by a polisher having a different contact area and hardness. There is a problem that undulations having a small amplitude and a long wavelength cannot be removed because they are to be removed.
[0010]
In the technique described in JP-A-9-323249, the polishing tool is provided with three or more polishers having a diameter of twice or more of the wobbling period removed, and each polisher can be tilted independently. Since we are trying to remove waviness, if the overall lens size is small and the wave length of waviness is longer than half of the whole lens shape, waviness cannot be removed, especially in the case of a free-form surface whose curvature is reversed. However, with such a tool shape, there was a problem that undulation could not be removed.
[0011]
Therefore, the present invention is not affected by waviness by two-point contact polishing, follows the processed surface shape, and moves the polishing pressing force between both contact points (surfaces) without breaking the processed surface shape. small amplitude, are intended to provide a polishing how to remove waviness having a wavelength longer than the tool contact width.
[0012]
Specifically, a first aspect of the present invention, the polishing following the shape of the machined surface of the workpiece while pressing the working surface of the workpiece a polishing tool across a rotating are not bent at grinding pressing force pressing force have line scanning polished by while controlling the constant a polishing method wherein the polishing tool has a polishing contact point of two points on the working surface, the axis of rotation of the polishing tool, the two places By making the straight line connecting the polishing contact points parallel to the traverse direction of the polishing tool, the undulation having a small amplitude and a wavelength longer than the contact width of the polishing tool is enlarged, and the polishing tool and the polishing tool are enlarged. It can be removed reliably and efficiently, and it eliminates waviness along the polishing direction without destroying the shape of the machined surface, and reliably and efficiently has a small amplitude and a wavelength longer than the contact width of the polishing tool. Have And its object is to provide a polishing method capable of removing Ruuneri.
[0013]
According to the second aspect of the present invention, the polishing pressing force is made constant according to the shape of the work surface of the work piece while pressing the polishing tool which does not bend as a whole against the work surface of the work piece with the polishing press force. In a polishing method in which polishing is performed by scanning while being controlled, and the polishing tool has two polishing contact points on the processing surface, a straight line connecting the rotation axis of the polishing tool and the two polishing contact points Is parallel to the traverse direction of the polishing tool, and the polishing pressing force is averaged at the two polishing contact points in a place where there is no waviness on the work surface, but with the traverse of the polishing tool, by the polishing pressing force to polish the contact point of the polishing direction top side in contact with the mountain portion of the undulation present on the working surface is concentrated, 2 against waviness mountains in one traverse Kaise' Polishing and removing the waviness more reliably and efficiently and distributing the polishing pressing force at the two polishing contact points (surfaces) to perform roughing and finishing simultaneously An object of the present invention is to provide a polishing method that can be used.
[0020]
[Means for Solving the Problems]
The polishing method of the first aspect of the present invention, the polishing pressing force along the shape of the machined surface of the workpiece while pressing the working surface of the workpiece a polishing tool across a rotating are not bent at grinding pressing force There line while controlling polished by scanning a constant, the polishing method wherein the polishing tool has a polishing contact point of two points on the working surface, the axis of rotation of the polishing tool, the polishing contact of the two locations The above object is achieved by making a straight line connecting the points parallel to the traverse direction of the polishing tool .
[0021]
According to the above configuration, by controlling a constant the polishing pressing force along the shape of the machined surface of the workpiece while pressing the working surface of the workpiece a polishing tool across a rotating are not bent at grinding pressing force When performing polishing while scanning, the polishing tool has two polishing contact points on the processing surface, and the rotation axis of the polishing tool and a straight line connecting the two polishing contact points are Because it is parallel to the traverse direction of the tool, undulations having a small amplitude and a wavelength longer than the contact width of the polishing tool can be reliably and efficiently removed without increasing the size of the polishing tool or the polishing tool. be able to.
[0023]
In addition, since the straight line connecting the two polishing contact points of the polishing tool is parallel to the traverse direction of the polishing process, waviness can be removed along the polishing process direction without breaking the shape of the processing surface, Waviness having a small amplitude reliably and efficiently and having a wavelength longer than the contact width of the polishing tool can be removed.
[0024]
According to the polishing method of the invention of claim 2, the polishing tool follows the shape on the work surface of the work piece while pressing the rotating tool which does not bend as a whole against the work surface of the work piece with a polishing pressing force. In a polishing method in which a polishing process is performed by scanning while controlling the pressing force to be constant, and the polishing tool has two polishing contact points on the processing surface, the rotating shaft of the polishing tool and the two polishing points In a place where the straight line connecting the contact points is parallel to the traverse direction of the polishing tool and there is no waviness on the work surface, the polishing pressing force is averaged at the two polishing contact points. As the tool traverses, the polishing pressing force may be concentrated at the polishing contact point on the leading side in the polishing process direction that contacts the waviness peak portion existing on the processing surface.
[0025]
According to the above configuration , the polishing pressing force is averaged at the two polishing contact points in a place where there is no waviness on the processing surface, but the waviness existing on the processing surface as the polishing tool traverses. Since the polishing pressing force concentrates on the polishing contact point on the leading side in the polishing direction in contact with the crest portion, polishing is performed by contacting the waviness mountain twice with one traverse to remove the waviness. Can be performed more reliably and efficiently, and the polishing pressing force at two polishing contact points (surfaces) can be distributed to perform roughing and finishing simultaneously.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. The embodiments described below are preferred embodiments of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. As long as there is no description which limits, it is not restricted to these aspects.
[0037]
1 to 5 are diagrams showing a first embodiment of a polishing method, a polishing tool, and an optical component of the present invention. FIG. 1 is a first view of a polishing method, a polishing tool, and an optical component of the present invention. It is a front view of the grinding | polishing tool used for the grinding | polishing method to which embodiment is applied.
[0038]
In FIG. 1, a polishing tool 1 includes a spherical polishing section 2 and a polishing section 3 of the same size connected by a shaft 4, and the shaft 4 has a central axis 2 a of the spherical polishing section 2 and the center of the polishing section 3. The shaft 3a is connected. In the polishing tool 1, the polishing unit 2 and the polishing unit 3 are respectively in contact with the processed surface of the workpiece to perform polishing, and the polishing unit 2 and the polishing unit 3 are polished on the processed surface of the workpiece. It has a contact point (surface).
[0039]
When the polishing tool 1 is pressed against the processing surface, as shown in FIG. 2, the distance between two polishing contact points (surfaces) with respect to the processing surface of the workpiece of the polishing portion 2 and the polishing portion 3 is d and Then, the polishing part 2 and the polishing part 3 are connected by the shaft 4 in a state where the distance d satisfies the following Hertzian expression.
[0040]
[Expression 2]

_A is the maximum contact circle radius when the polishing tool 1 is pressed against the work surface, F is the tool pressing force, R _A is the tool curvature radius, E _A is the longitudinal elastic modulus of the tool, and ν _A is , Poisson's ratio of the tool, R _B is the radius of curvature of the working surface of the workpiece, E _B is the modulus of longitudinal elasticity of the workpiece, [nu _B is the Poisson's ratio of the workpiece.
[0041]
That is, as shown in FIG. 2, the sum of the maximum contact circle radii at the two polishing contact points (surfaces) by the polishing portion 2 and the polishing portion 3 by the pressing force F is the two polishing contact points ( The polishing tool 1 is made of a material whose elastic deformation does not integrate the two polishing contact points (surfaces). In particular, the polishing tool 1 has a shaft 4 made of a cemented carbide or ceramic with extremely small elastic deformation.
[0042]
Next, the operation of the present embodiment will be described. When a workpiece having a flat surface as a processing surface is polished using the polishing tool 1, the following procedure is used.
[0043]
That is, as shown in FIG. 3, while the polishing tool 1 has two polishing points (surfaces) on the processing surface 11 of the workpiece 10, the shape on the processing surface 11 is adjusted and the pressing force P is constant. Polishing is performed. In the polishing of the planar workpiece 10, the balance of the forces of the polishing tool 1 and the processed surface 11 of the workpiece 10 at the start is represented by the following equations (2) and (3) as shown in FIG. ) Is satisfied.
[0044]
N ₁ = P ₁ = (1/2) × P = (1/2) × N (2)
N ₂ = P ₂ = (1/2) × P = (1/2) × N (3)
Here, P ₁ and P ₂ are pressing forces of the polishing unit 2 and the polishing unit 3, and N ₁ and N ₂ are repulsive forces thereof.
[0045]
When processing is started in the above state, an unremoved portion becomes high between the contact points (surfaces) of the polishing portion 2 and the polishing portion 3 as shown in FIG. .
[0046]
The polishing direction is the right direction of FIGS. 3 and 4 indicated by arrows as the processing directions in FIGS. 3 and 4. As the polishing process proceeds to the right, the polishing unit 2 and the polishing unit 3 are moved. As shown in FIG. 5, the crest portion between the two is removed by the left polishing unit 2, and both contact points (surfaces) of the polishing unit 2 and the polishing unit 3 of the polishing tool 1 become the same horizontal plane again. .
[0047]
In this state, when the polishing proceeds in the right direction, as shown in FIG. 5, only the polishing part 3 on the front end side in the processing direction starts to process the unprocessed processing surface 11 of the workpiece 10. Thus, the relational expression of the above expression (2) and the expression (3) does not hold, and as shown in FIG. 6, the new relational expressions of force balance of the following expressions (4) to (7) are satisfied. Become.
[0048]
N ₁₁ = P ₁₁ (4)
N ₂₂ = P ₂₂ (5)
N ₂₃ = P ₂₂ · cos θ (6)
N ₁₁ + N ₂₂ = N = P (7)
Now, the polishing tool 1, particularly the shaft 4, is formed of a material having extremely small elastic deformation, and the entire polishing tool 1 does not bend. Therefore, when the polishing tool 1 further proceeds in the right direction, the result is shown in FIG. 7. As described above, the pressing force P for polishing is completely transferred to the contact point (surface) of the polishing unit 3 on the right side. In FIG. 7, since the amount of polishing removal by the polishing tool 1 is small, the angle θ formed between the processed surface 11 being polished and the unpolished processed surface 11 is small, close to 0, and cos θ> 1/2. Therefore, the above formula (6) is expressed by the following formula (8).
[0049]
N ₂₃ = P cos θ> N ₂ = (1/2) × P (8)
When the processed surface 11 of the workpiece 10, that is, the workpiece surface is a perfect plane, the above equation (8) always holds, and when the reciprocating polishing is performed, the polishing pressing force P is equal to the left and right polishing. It is possible to repeatedly change at two polishing contact points (surfaces) of the part 2 and the polishing part 3 and to polish the processed surface 11 of the workpiece 10 by changing the left and right contact points (surfaces).
[0050]
If a tool material having an elastic coefficient different from that of the polishing pressing force P (the same material is used for the entire polishing tool 1) is selected, the polishing pressing force P is not completely transferred to one polishing contact point (surface), and polishing is performed at two locations. It can be distributed to the contact points (surfaces) at a constant rate.
[0051]
Therefore, it is possible to perform roughing at the previous contact point (surface) and finish processing at the subsequent contact point (surface) simultaneously with respect to the polishing progress direction.
[0052]
Although the work surface 11 of the workpiece 10 is not shown, when the work surface 11 is a spherical surface, an aspheric surface, or a free-form surface, in the polishing process for removing the waviness on the spherical surface, aspheric surface, or free-form surface, the work surface In accordance with the shape of the polishing tool, the polishing pressing force is controlled to be constant, the polishing tool 1 is reduced in diameter, and the distance between the two contact points (surfaces) is shortened so that the polishing tool 1 can process the workpiece surface. Follow the shape above, but not swell.
[0053]
Therefore, only waviness in the shape can be removed by moving the polishing pressing force at the two polishing contact points (surfaces) without breaking the shape on the processed surface of the workpiece.
[0054]
8 and 9 are diagrams showing a second embodiment of the polishing method, the polishing tool, and the optical component of the present invention.
[0055]
In the present embodiment, polishing is performed using a polishing tool similar to the polishing tool 1 of the first embodiment, and in the description of the present embodiment, the first embodiment is used. The description will be made using the used symbols as they are.
[0056]
FIG. 8 shows the force balance when the polishing tool 1 climbs a mountain of undulations 20 with a small amplitude on the flat work surface 11 of the work piece 10 and a wavelength longer than the contact width of the polishing tool 1. .
[0057]
In this case, since the amplitude of the undulation 20 is small and the wavelength is long, the angle θ formed between the processed surface 11 and the surface of the undulation 20 is slightly larger than that in the first embodiment. The relationship of cosθ> ½ is not broken. Therefore, the relational expression (8) holds as it is.
[0058]
Then, as the polishing process by the polishing tool 1 proceeds to the right, when the polishing contact point of the right polishing section 3 exceeds the peak of the undulation 20, as shown in FIG. Will move to the contact point (surface) of the polishing unit 2 on the left side, and the balance of force at this time satisfies the following equation (9) as shown in FIG.
[0059]
N ₁₃ = P cos θ> N ₁ = (1/2) × P (9)
Therefore, in one traverse polishing process, the polishing tool 1 can come into contact with the ridge of one swell 20 twice, and the wavelength of the polishing tool 1 has a wavelength larger than the contact width of the polishing tool 1 more reliably and efficiently. The waviness 20 having a long and small amplitude can be removed.
[0060]
When the polishing tool 1 is used to polish the optical component molding die, the undulation having a small amplitude and a wavelength longer than the contact width of the polishing tool 1 can be easily removed without breaking the shape of the processed surface. An optical component molding die can be polished efficiently and with higher accuracy.
[0061]
When the optical component is molded using this optical component molding die, an optical component with excellent shape accuracy can be obtained.
[0062]
In each of the above embodiments, the polishing tool 1 is not limited to the shape described above. For example, as shown in FIG. 10, the polishing tool 30 includes spherical polishing portions 31 and 32 having a predetermined shape. It is connected in a state where the contact surface is shared, and the center axis 33 may pass through the centers of the polishing unit 31 and the polishing unit 32.
[0063]
In the case of the polishing tool 30, as in the polishing tool 1, the contact points of the polishing portion 31 and the polishing portion 32 with the processing surface of the workpiece become polishing contact points (surfaces), and polishing is performed at two locations. It will have a contact point (surface). Although not shown, the polishing tool 30 is connected to a shaft for rotating the polishing tool on the central shaft 33.
[0064]
Further, as shown in FIG. 11, the polishing tool 40 has a central axis 42 passing through the center of one large spherical polishing portion 41, and has a predetermined width w in the circumferential direction of the central axis 42. A groove 43 having a predetermined depth h is formed. A shaft 44 is connected to the central shaft 42, and the polishing tool 40 is driven to rotate about the central shaft 42.
[0065]
As shown in FIG. 12, the polishing tool 40 has two polishing contact points (surfaces) where a contact point between the polishing portion 41 and the processed surface of the workpiece is a polishing contact point (surface) across the groove 43. In this case, the width d and the depth h of the groove 43 are set so that the distance d between the polishing contact points (surfaces) satisfies the Hertz formula.
[0066]
The invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to the above, and various modifications can be made without departing from the scope of the invention. Needless to say.
[0067]
【The invention's effect】
According to the polishing method of the invention described in claim 1, the polishing following the shape of the machined surface of the workpiece while pressing the working surface of the workpiece a polishing tool across a rotating are not bent at grinding pressing force When performing polishing by scanning while controlling the pressing force to be constant, the polishing tool has two polishing contact points on the processing surface, the rotation axis of the polishing tool, and the two polishing contact points. Since the connecting straight line is parallel to the traverse direction of the polishing tool, undulation with a small amplitude and a wavelength longer than the contact width of the polishing tool can be ensured without increasing the size of the polishing tool or the polishing tool. And can be removed efficiently.
[0068]
Also, it is possible to remove waviness along the polishing direction without destroying the shape of the machined surface, and to remove waviness having a wavelength that is smaller in amplitude and longer than the contact width of the polishing tool reliably and efficiently. Can do.
[0069]
According to the polishing method of the second aspect of the present invention, the polishing pressing force is averaged at the two polishing contact points in a place where there is no waviness on the processed surface. Since the polishing pressing force concentrates on the polishing contact point on the leading side in the polishing process direction that contacts the waviness peak portion existing on the processing surface, polishing is performed by contacting the waviness peak twice with a single traverse. Roughness and finishing can be performed at the same time by distributing the polishing pressing force at the two polishing contact points (surfaces) as well as removing undulation more reliably and efficiently. it can.
[Brief description of the drawings]
FIG. 1 is a front view of a polishing tool applied to a first embodiment of a polishing method, a polishing tool, and an optical component of the present invention.
FIG. 2 is a diagram showing a tool deformation state and a contact point interval when the polishing tool of FIG. 1 is pressed against a processing surface of a workpiece with a polishing pressing force.
3 is a perspective view when machining of a planar machined surface is started with the polishing tool of FIG. 1. FIG.
4 is a front view of a state where polishing is performed with the polishing tool of FIG. 3; FIG.
5 is a front view showing a state where the polishing with the polishing tool of FIG. 4 has further progressed. FIG.
6 is a diagram showing a force balance relationship acting on the polishing tool in the state of FIG. 5 and a machining surface;
7 is a diagram showing a force balance relationship at a polishing contact point on the leading side in the polishing direction in FIG. 6;
FIG. 8 is a front view showing a state in which a processing surface having a warp longer than the contact point interval is being polished by the polishing tool applied to the polishing method, the polishing tool, and the optical component according to the second embodiment of the present invention. .
FIG. 9 is a front view showing a state where polishing is performed at a polishing point on the rear side in the polishing direction beyond the undulation of FIG. 8;
FIG. 10 is a front view showing another example of a polishing tool.
FIG. 11 is a front view showing still another example of the polishing tool.
12 is a diagram showing a tool deformation state and a contact point interval when the polishing tool of FIG. 11 is pressed against a processing surface of a workpiece with a polishing pressing force.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Polishing tool 2, 3 Polishing part 2a, 3a Center axis 4 Shaft 10 Workpiece 11 Work surface 20 Waviness 30 Polishing tool 31, 32 Polishing part 33 Central axis 40 Polishing tool 41 Polishing part 42 Central axis 43 Groove 44 Shaft

Claims

While rotating the polishing tool that does not bend entirely against the work surface of the workpiece with the polishing pressing force, the polishing tool is scanned and polished while controlling the polishing pressing force constant according to the shape on the processing surface of the workpiece. In the polishing method in which the polishing tool has two polishing contact points on the processing surface,
A polishing method, characterized in that a rotation axis of the polishing tool and a straight line connecting the two polishing contact points are parallel to a traverse direction of the polishing tool.

While rotating the polishing tool that does not bend entirely against the work surface of the workpiece with the polishing pressing force, the polishing tool is scanned and polished while controlling the polishing pressing force constant according to the shape on the processing surface of the workpiece. In the polishing method in which the polishing tool has two polishing contact points on the processing surface,
In a place where the rotation axis of the polishing tool and the straight line connecting the two polishing contact points are parallel to the traverse direction of the polishing tool and there is no waviness on the processing surface, the polishing pressing force is the two points. As the polishing tool traverses, the polishing pressing force concentrates on the polishing contact point on the leading side in the polishing direction that contacts the waviness peak portion existing on the processing surface. A polishing method comprising: