JP3575540B2

JP3575540B2 - Numerical control polishing method

Info

Publication number: JP3575540B2
Application number: JP2000343055A
Authority: JP
Inventors: 利彦阿部; 修一武田; 三男佐藤
Original assignee: Applied Diamond Inc; National Institute of Advanced Industrial Science and Technology AIST
Current assignee: Applied Diamond Inc; National Institute of Advanced Industrial Science and Technology AIST
Priority date: 2000-11-10
Filing date: 2000-11-10
Publication date: 2004-10-13
Anticipated expiration: 2020-11-10
Also published as: JP2002144197A

Description

【０００１】
【発明の属する技術分野】
本発明は、多結晶ダイヤモンド、ダイヤモンド単結晶、ダイヤモンド薄膜(気相合成法により基板上に形成したダイヤモンドまたは自立膜(箔、平板、3次元形状体を含む)、ダイヤモンド焼結体等のダイヤモンドそれ自体またはダイヤモンドを含む材料を研磨加工能力の優れた金属間化合物砥石と数値制御機構を有する加工装置を用いて、鏡面で、かつ、うねり、端部だれ等の極めて少ない高い形状精度を有し、高い再現性と研磨加工能率を実現できる研磨加工方法及び従来法では事実上研磨加工が不可能であった高精度 3 次元形状研磨加工方法に関する。
【０００２】
【従来の技術】
今日、ダイヤモンドを利用した材料の１つとしてダイヤモンド薄膜が注目されている。このダイヤモンド薄膜は気相合成法（ＣＶＤ法）等により、工業的（人工的）に多結晶粒からなるダイヤモンド薄膜（基板上に形成された薄膜及びダイヤモンド膜被覆部材）又はダイヤモンド自立膜を製造することができるようになったが、上記合成法により得られた多数の結晶粒からなるダイヤモンド薄膜は凹凸の激しい表面を持っている。
このため、気相合成法により形成されたダイヤモンド薄膜を電子部品、光学部品、超精密部品あるいは加工工具等に使用する場合には、光学ミラーやフライス工具に代表されるように３次元の極めて高い形状精度を達成しつつ、ダイヤモンド表面を平滑化することが必要となってくる。
【０００３】
また、天然及び人工単結晶ダイヤモンド（超高圧合成、気相合成法等による）は、砥石のドレッサー、刃物、ダイス、ヒートシンク、Ｘ線窓、電子部品基板等各種の工業製品又は宝飾品として使用されているが、最終的にそれぞれの用途に適用できる形状精度に仕上げる必要がある。
さらにダイヤモンドを利用したダイヤモンド焼結体は、その特性を利用して、自動車用エンジン等の高速精密研削又は研磨、超硬合金の精密研削又は研磨用工具、切削又は切断用刃物、耐磨耗機構用部品、通信機用ヒートシンクあるいはパッケージ等高い形状精度と極めて平滑な表面仕上げ（表面粗さ）が求められる用途に普及しつつある。
なお、ダイヤモンド焼結体は結合剤としてＣｏ、ＷＣ、ＴｉＣなどが使用されているが、また結合剤を殆ど含まないあるいは全く含まないものもある。本発明では特に言及しない限り、これらの焼結体を全て含むものとする。
【０００４】
ダイヤモンドは、それ自身が他の金属やセラミックス等硬質材料の研磨あるいは宝石の微細研磨加工に使用される程に、極めて硬い物質なので、ダイヤモンドを高い形状精度と極めて平滑な表面仕上げで研磨加工することが難しいことは、誰でも容易に理解できる。
このような多数の凹凸を有する気相合成ダイヤモンド薄膜、多結晶ダイヤモンド膜又は自立体を平滑化する方法として、強靭な鋳鉄板を高速に回転させながら鋳鉄板上でダイヤモンド砥粒により共擦り（共削り）研磨加工するスカイフ法が挙げられる。
この方法は、天然単結晶の宝石への微細研磨加工に古くから用いられてきた手法であるが、上記ダイヤモンド薄膜等を研磨加工する方法としては極めて加工能率が低く、μｍオーダーの形状精度研磨加工も期待できないことから殆ど役に立たない。
【０００５】
特に、上記ダイヤモンド単結晶は、結晶面あるいは結晶方位により、硬さの変化が著しく、現状で下降できる面は（１００）面や（１１０）面等に限定され、研磨面の形状精度も制御され研磨加工しているとは言いがたい。
硬さや熱伝導性等に最も優れている（１１１）面の研磨加工は、極めて困難であり、事実上不可能と言われている。
このようなことから、ダイヤモンド単結晶の研磨加工に際しては研磨可能な面を中心に、これらの結晶面や結晶方位を調べつつ研磨する高い熟練技術が必要とされており、ダイヤモンドの研磨加工を複雑かつコスト高にしていた。
【０００６】
また、ダイヤモンド燒結体の研磨加工では、後述するようなダイヤモンド砥石（共ずり）による研磨加工方法では、燒結体中のダイヤモンド粒子と結合剤の硬さの差あるいは個々のダイヤモンド粒子の結晶面、方位の違いに基づく硬さの差から、加えて研磨加工中、燒結体中の多数のダイヤモンド粒子が脱落することにより大きな段差（数μｍ程度）が生じ易く、このような燒結体を加工工具として使用する場合、段差に起因する転写加工での加工精度の低下、そして耐磨耗性機構部品として使用する場合には摩擦特性が低下するという問題があり、
また、燒結体中のダイヤモンド粒子自体も損傷を受けることから、使用中に脱落し、自分自身を傷つけ致命的なトラブルを引き起こすという使用上のリスク問題が発生した。
【０００７】
上記に述べたように、ダイヤモンドの硬さは代替物が無いほどに硬い材料なので、研磨加工材としてはダイヤモンド（共ずり）以外にないと考えるのが普通である。このため表面に多数の凹凸を有する気相合成ダイヤモンド薄膜、多結晶ダイヤモンド膜又は自立体を特に平面にて平滑化する方法として、ダイヤモンド砥石（共ずり）研磨加工法が挙げられる。
ダイヤモンド砥石は、通常体積率にて２５％程度のダイヤモンド砥粒を結合剤で保持したものであり、結合材としてフェノール樹脂を用い破砕性の高いダイヤモンド砥粒を使用した切れ味重視のレジンボンド砥石、砥粒強度が高く、砥粒保持力すなわち工具剛性の高いメタルボンド砥石、ビトリファイド（ガラス）ボンド砥石などがある。
本気相合成ダイヤモンド薄膜、多結晶ダイヤモンド膜又は自立体の研磨加工では、被研磨加工材表面は上記砥石中の研磨加工に作用するダイヤモンド砥粒数（切り刃数）に比して圧倒的な数の凹凸切り刃を有すること、研磨加工機構が硬さの同じ材料で破砕、磨耗で進行する共ずり加工であり、研磨加工速度が極めて低い割には砥石磨耗が激しいことから、形状精度の高い研磨加工は難しい。
加えて砥石剛性が被研磨加工材に比べ明らかに低いことも加工精度低下の原因となっている。
【０００８】
研磨加工速度並びに形状精度の向上を目的とした一つの方法として、硬質で高剛性の鋳鉄を結合剤としたメタルボンド砥石を用いて、研磨加工中、研磨加工に有効に作用するダイヤモンド砥粒切り刃の目立てを電気化学的に自動化した研磨加工法がある。
この方法は上記手法に比べると研磨加工性能の向上が期待できるが、使用できるダイヤモンド砥粒体積率は同じであることから、研磨速度の向上には、砥石への高荷重負荷が必須であり、形状精度の向上には更に高い剛性の高価な加工装置、砥石剛性の向上が必要であるというジレンマが残っている。
【０００９】
上記以外の方法として、鉄やステンレス鋼をダイヤモンドに押し付けて研磨する提案がなされた。ダイヤモンドは常温では化学的に安定であるが、空気中で７００°Ｃに加熱すると黒鉛化して燃焼し始め、真空中でも１４００°Ｃ以上になると黒鉛化する。上記の方法はこのような高温における鉄とダイヤモンドとの反応を利用して研磨する方法である。
鉄とダイヤモンドの反応（ダイヤモンド成分の炭素が金属中に溶解する）は８００°Ｃ程度から生じ、Ｆｅ_３Ｃ（セメンタイト）が生成し、研磨中の摩擦面ではこれが剥離し、さらに研磨が進行することを利用したものと理解されている。
高温ではこの反応がさらに進行し易くなり、Ｆｅ_３Ｃの生成・分解が起り、研磨が進む。加工能率を考慮すると９００°Ｃ以上が必要といわれている。
【００１０】
この鉄又は鉄系材料は安価な研磨材を使用できるという点で良い方法と考えられたが、この方法の一番の問題は、高温に加熱しなければ効果的な研磨が出来ないということである。
ところが、ステンレスや鉄系材料は高温で軟化し、強度が著しく低下するので、研磨加工中、砥石の剛性、形状精度は維持できないという欠点の他に、熱容量の高い砥石が被研磨加工材に接触することから、熱膨張の揺らぎ等により形状精度を議論できる寸法精度の研磨加工は事実上不可能な難点がある。
特に、高温の鉄を用いる場合には、鉄の酸化を防止するために、真空中あるいは還元性雰囲気中で研磨を実施する必要があるため、設備の面でも又研磨作業が煩雑である（自在にできない）という点でも問題がある。
【００１１】
さらにまた、上記のような高温加熱は被研磨加工体であるダイヤモンド、基板材にも影響を与え、急激な温度勾配による複雑な熱応力からダイヤモンドにクラックが発生したり、基板からダイヤモンド膜が剥離するなどの問題が生じた。
この他ＹＡＧレーザを斜入射したレーザ加工等が考えられるが、研磨加工面の形状並びに平滑な表面仕上げ精度（表面粗さ）が劣り、使用に耐えるものではなかった。
上記したように、研磨加工能力の優れた砥石と数値制御機構を有する加工装置を用いて、鏡面で、かつ、うねり、端部のだれ等の極めて少ない高い形状精度を有し、高い再現性と研磨加工能率を実現できる研磨加工方法、また、従来法では事実上研磨加工が不可能であった高精度３次元形状研磨加工方法並びにそのような研磨加工法により得られた鏡面で高い形状精度のダイヤモンド研磨加工体（ダイヤモンド薄膜、多結晶ダイヤモンド等を含む）、単結晶ダイヤモンド及びダイヤモンド燒結体は得られていなかった。
【００１２】
【発明が解決しようとする課題】
以上から、本発明は、ダイヤモンド単結晶、ダイヤモンド薄膜（気相合成法により基板上に形成したダイヤモンド又はダイヤモンド自立膜（箔、平板、３次元形状体を含む）、ダイヤモンド焼結体、その他の多結晶ダイヤモンド等の、ダイヤモンドそれ自体又はダイヤモンドを含む材料を鏡面で、かつ、うねり、端部のだれ等の極めて少ない高い形状精度を有し、高い再現性と研磨加工能率を実現できる研磨加工方法、及び従来法では事実上研磨加工が不可能であった高精度３次元形状研磨加工方法並びにそのような研磨加工法により得られた鏡面で高い形状精度のダイヤモンド研磨加工体（ダイヤモンド薄膜、多結晶ダイヤモンド等を含む）、単結晶ダイヤモンド及びダイヤモンド焼結体を得ることを課題とする。
本発明者は、すでにＡｌ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｒｕ、Ｒｈ、Ｐｄ、Ｏｓ、Ｉｒ、Ｐｔ、の群から選択した１種若しくは２種以上の元素とＴｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｍｏ、Ｔａ、Ｗの群から選択した１種若しくは２種以上の元素との金属間化合物を主成分とする砥石、または前記砥石に所定の量の複合粒子を含有する優れたダイヤモンド研磨用砥石を提案している（特願平１１−１３０９９１号、特願平１１−２１８８５０号、特願平１１−３２０５２３号、特願２０００−１２４７９号）。
本発明は、さらにこれらを展開し、鏡面で高い形状精度を有し、再現性と研磨加工能率に優れた研磨加工方法、また、従来法では事実上研磨加工が不可能であった高精度３次元形状研磨加工方法並びにそのような研磨加工法により得られた鏡面で高い形状精度のダイヤモンド研磨加工体（ダイヤモンド薄膜、多結晶ダイヤモンド等を含む）、単結晶ダイヤモンド及びダイヤモンド焼結体を提供するものである。
【００１３】
【課題を解決するための手段】
本発明は、
１．数値制御機構を有する加工装置を用いて、Al、Cr、Mn、Fe、Co、Ni、Cu、Ru、Rh、Pd、Os、Ir、Pt、の群から選択した1種若しくは2種以上の元素とTi、Zr、Hf、V、Nb、Mo、Ta、Wの群から選択した1種若しくは2種以上の元素との金属間化合物を主成分とする砥石又は前記砥石に複合粒子を含有する砥石を、一定圧力或いは一定切込み条件で、被研磨加工体であるダイヤモンド薄膜、ダイヤモンド単結晶、ダイヤモンド焼結体に対して相対運動させ、研磨加工することを特徴とするダイヤモンド薄膜、ダイヤモンド単結晶、ダイヤモンド燒結体の数値制御研磨加工方法
２．CAM（Computer Aided Machining）又はCAD（Computer Aided Design）とCAMプログラムにて制御駆動する数値制御加工装置を用いて研磨加工することを特徴とする上記１に記載の数値制御研磨加工方法
３．平面、凸面、凹面の群から選ばれた少なくとも１種以上の組み合わせで出来る平面、凹凸一定曲率面、自由曲面等を研磨加工できる数値制御加工装置を用いて研磨加工することを特徴とする上記１又は２記載の数値制御研磨加工方法
４．研磨加工用砥石を使用して被加工体に対して点接触、線接触又は面接触により定圧または定切込み加工することを特徴とする上記１〜３のそれぞれに記載の数値制御研磨加工方法
５．加工砥石に含有する複合粒子がダイヤモンドであることを特徴とする上記１〜４のそれぞれに記載の数値制御研磨加工方法
を提供するものである。
【００１４】
【発明の実施の形態】
本発明のダイヤモンド研磨加工用砥石は、例えば粉末冶金法によって製造することができる。この場合、原料粉末としてそれぞれ平均粒径１５０μｍ以下（好ましくは１０μｍ以下）のＴｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｍｏ、Ｔａ、Ｗの群から選択した１種または２種以上の粉末とＡｌ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｒｕ、Ｒｈ、Ｐｄ、Ｏｓ、Ｉｒ、Ｐｔの群から選択した１種または２種以上の粉末（以下、特に記載しない限り「砥石用粉末」と言う。）とを、それぞれの金属間化合物（以下、特に記載しない限り「金属間化合物の含有量が９０体積％以上であるもの」を含む。）が、本発明の金属間化合物の砥石となる組成及び比率に調合し、これらをボールミルで混合し、乾燥して混合粉とする。
原料粉としては、微細なアトマイズ粉を使用することができる。予めメカニカルアロイング法により所定の比率に合金化した砥石用粉末を用いることもできる。
微細かつ均一な混合粉末を使用した場合には、焼結体の密度が高く、その結果均一かつ緻密な砥石が得られるという利点がある。
これらの粉末は、単独の金属粉末であっても良いし、予め合金（金属間化合物）とした粉末、さらにこれらの複合粉末であっても良い。
【００１５】
次に、上記混合粉砕粉をモールドに入れ予備成形した後、例えば冷間静水圧処理（ＣＩＰ処理）し、さらに１０００〜１３００°Ｃ、圧力５００Ｋｇｆ／ｃｍ^２の条件でホットプレス焼結（ＨＰ処理）するか、又はＣＩＰ処理した後、同様に１０００〜１３００°Ｃ、圧力５００Ｋｇｆ／ｃｍ^２の条件で熱間静水圧焼結（ＨＩＰ処理）して高密度（相対密度９９％以上であることが望ましい）の焼結体とする。
ＣＩＰ処理、ＨＰ処理、ＨＩＰ処理等の温度、圧力等の条件は上記に限らず、原料の種類又は目的とする焼結体の密度等を考慮して他の条件を設定してもよい。
また、上記のようなＣＩＰ処理、ＨＰ処理、ＨＩＰ処理等に替えて、黒鉛製のモールドに混合粉末を充填し、これを上下パンチ（電極）間で圧縮しながらパルス通電により加熱する方法、すなわちパルス通電焼結法により焼結体とすることもできる。この場合、特に上記メカニカルアロイ粉を使用すると緻密かつ均一な焼結体を得ることができる。
【００１６】
本発明の金属間化合物を主成分とする合金砥石は、真空アーク溶解、プラズマ溶解、電子ビーム溶解、誘導溶解等の溶製法によっても製造できる。これらの溶解に際してはガス、特に酸素の混入が著しく、また上記アルミニウム等の金属間化合物を形成する元素およびチタンはいずれも酸素との結合力が強いので、真空中又は不活性ガス中で溶解することが必要である。
また、これらの金属間化合物を主成分とする合金砥石の鋳造品は機械的強度が焼結品よりも劣る傾向があるので、溶解、凝固過程において偏析の発生や結晶粒が粗大化しないように、温度コントロールを実施して製造することが必要である。
上記粉末冶金法又は溶製法によって得られた燒結体又はインゴットから必要な砥石形状に切り出し、数値制御機構を有する加工装置、また、被研磨加工体の形状、研磨加工精度に適合する形状に仕上げ、かつこの金属間化合物砥石保持具等の構成部品等で固定してダイヤモンド研磨加工用砥石工具とする。
【００１７】
被研磨体の一例として、ダイヤモンド薄膜又はダイヤモンド自立体を挙げると、このダイヤモンド薄膜又はダイヤモンド自立体は一般に知られている気相成長法（ＣＶＤ法）によって作成できる。
例えば、高温（２０００°Ｃ前後）に加熱したタングステンフィラメントの近傍位置に開口する石英管を配置し、この石英管を通してメタン等の炭化水素ガスを水素で希釈した混合ガスを導入し、５００°Ｃ〜１１００°Ｃに加熱した基板上にダイヤモンドを前記混合ガスから分解析出させる方法、上記タングステンフィラメントに替えて、プラズマ放電を利用したマイクロ波プラズマＣＶＤ法、ＲＦ（高周波）プラズマＣＶＤ法、ＤＣ（直流）アークプラズマジェット法、さらには大気中で酸素アセチレンの火炎を高速で基板に当て、ダイヤモンドを炭化水素含有ガスから分解析出させる方法がある。
本発明においてはこれらの方法あるいは他の方法によって製作されたダイヤモンド薄膜又はダイヤモンド自立体に適応できる。
【００１８】
上記ダイヤモンド研磨加工用砥石工具を用いて数値制御機構を有する加工装置で研磨加工を実施することにより、天然のダイヤモンド又は人工ダイヤモンドも鏡面にて、高い形状精度で所望の形状に再現性、効率良く研磨加工できる。特にダイヤモンド単結晶（１１１）面の研磨加工が従来技術では不可能と言われているが、本発明の研磨加工方法によれば、この（１１１）面を鏡面にて３次元段差を有する立体形状デバイス用にも高い形状精度で研磨加工でき、新しい応用が期待できる。この（１１１）面の研磨加工が可能になったことにより、切削工具のすくい面に高品質の（１１１）面を使用することができ、また砥石の精密ツルーアとして（１１１）面を用いた高性能ダイヤモンド単石ドレッサー、高熱伝導ヒートシンクなどの高性能で付加価値の高いダイヤモンド単結晶も得ることができる。
【００１９】
被研磨加工体がダイヤモンド燒結体の場合にも同様に数値制御機構を有する加工装置で研磨加工を実施することにより、極めて高い形状精度で所望の形状に再現性、効率良く研磨加工できる。
ダイヤモンド砥石（共ずり）研磨加工方法で発生するような、燒結体中のダイヤモンド粒子と結合剤の硬さの差あるいは個々のダイヤモンド粒子の結晶面、方位の違いに基づく硬さの差から、加えて研磨加工中、燒結体中の多数のダイヤモンド粒子が脱落することにより大きな段差（数μｍ程度）が発生することが殆どなく、このような段差に起因する転写加工での加工精度の低下の問題も発生しない。
そして耐磨耗性機構部品として使用する場合に発生しがちな摩擦特性の低下という問題もなく、特に高い形状精度と極めて平滑な表面仕上げ状態が得られることで応用分野も一段と拡大する。
【００２０】
数値制御機構を有する加工装置としては、一軸制御機械では、ホーニング研削盤など、ニ軸制御機械では、ＣＮＣ旋盤、ＣＮＣ円筒研削盤、ＣＮＣ内面研削盤など、三軸制御機械では、ＮＣフライス盤、ＣＮＣターニング旋盤、ＣＮＣマシニングセンター並びにＣＮＣグラインディングセンター、四軸及び五軸制御機械では、例えばＮＣ工具研削盤、横型ＣＮＣマシニングセンター、六軸制御以上の機械では、一例として縦横マシニングセンター等が使用できるが、必ずしも上記機械に限定されるものではないことは明らかであり、被研磨加工体の形状等目的に応じて、各種加工装置を併用できることは明らかである。
また、この数値制御機構を有する加工装置をＣＡＭ（ＣｏｍｐｕｔｅｒＡｉｄｅｄＭａｃｈｉｎｉｎｇ）またはＣＡＤ（ＣｏｍｐｕｔｅｒＡｉｄｅｄＤｅｓｉｇｎ）とＣＡＭプログラムにて制御駆動することで、被研磨加工体を所望の鏡面で、かつ、うねり、端部だれ等の極めて少ない高い形状精度をえるために砥石の最適の研磨加工軌跡を再現性よく制御でき、ＣＡＤ（ＣｏｍｐｕｔｅｒＡｉｄｅｄＤｅｓｉｇｎ）とＣＡＭプログラムで制御駆動すれば、従来法では事実上研磨加工が不可能であった高精度３次元形状の研磨加工が実現し、高い形状精度と極めて平滑な表面（表面粗さ）をもつ複雑自由曲面を有する高機能ダイヤモンド製品を提供できる。
【００２１】
また、研磨加工用砥石は、被研磨加工体に対して線接触、面接触により定圧または定切込み加工が可能な形状、構成を有することで優れた鏡面と超精密形状精度を併せ持つ複雑自由曲面の研磨加工が実現する。線接触砥石を使用すれば、砥石の研削抵抗が極端に低下し、平坦面研磨加工では、端部のダレは従来法の一桁以上は改善する。また自由曲面等の研磨加工精度も飛躍的に向上する。
また、面接触砥石では平坦面をうねりの問題も極めて少なく、短時間で高精度な鏡面研磨加工が実現する。研磨加工実施時の砥石の選択は、被研磨加工体の種類、形状、また、要求研磨加工品質に応じて適時選択できることは言うまでも無い。
本研磨加工方法では、被研磨体の高い形状精度をうるため、定圧または定切り込み研磨加工を実施することが好ましい。しかし、本砥石の優れた研磨加工能力により、従来法で使用されてきた定荷重の研磨加工方式“所謂ラップ”加工にも使用できることは明らかである。
【００２２】
本発明の数値制御機構を有する加工装置で前記構成からなる砥石を用いた研磨加工に際しては、高い形状精度を達成する観点から室温（常温）で研磨加工を実施することが好ましい。しかし、後述するようにダイヤモンドの厚みが大きく結晶粒が大きい（数十μｍ以上の膜厚を有し、数十μｍの結晶粒を持つケース）場合、１００〜８００℃に加熱しながら研磨することが有効である。
上記のように基板上に形成されたダイヤモンド薄膜等の厚みが薄い場合、例えば１０μｍ程度であると、ダイヤモンド表面の凹凸が数μｍ程度なので、研磨の抵抗が小さく、常温でも十分に研磨できる。
ダイヤモンドと砥石の接触点では、摩擦熱により、局部的にかなりの高温となるが、このような状況において、例えばＴｉＣ、ＴｉＡｌＣ、ＴｉＡｌＣＮなどの本発明の砥石成分（Ａｌ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｒｕ、Ｒｈ、Ｐｄ、Ｏｓ、Ｉｒ、ＰｔあるいはＴｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｍｏ、Ｔａ、Ｗ）との脆い炭化物、炭窒化等が生成し、かつこれが剥離するなどによって、より効果的にダイヤモンドの研磨（化学的研磨）が進行しているものと推測される。
【００２３】
これに対し、厚膜ダイヤモンドの場合には、研磨加工効率の観点から加熱が有効である。
この場合の加熱に際しては、砥石及び又は研磨する個所の少なくとも一部を加熱し、研磨部の温度が上記１００〜８００°Ｃになるように調節して研磨する。
外部から加熱の温度が１００°Ｃ未満では合金砥石の靭性が劣り、砥石の割れが発生し易くなる。また、ダイヤモンド自体も上記加熱及び摩擦熱によりほぼ同等の加熱を受けるが、８００°Ｃを超えるとダイヤモンド等が受ける熱影響によりクラックが生じたり、割れたりすることが多くなり、ダイヤモンド等を損傷し易くなるので避ける必要がある。この加熱温度としては３００〜５００°Ｃがより好適である。
研磨部にかかる外部加熱の全熱が上記の温度範囲となるように調節する。摩擦熱による温度上昇を考慮して、温度設定することが必要であるが、摩擦熱により突発的に８００°Ｃを超える場合があってもよい。本発明において設定する加熱温度は、そのような突発的温度上昇は本発明の加熱温度に含めない。
【００２４】
本発明のダイヤモンド研磨用砥石は、ステンレス鋼に比べ室温での硬さが極めて大きいという特徴がある。粉末法によって得た本発明の金属間化合物砥石の硬度がＨｖ５００〜１０００Ｋｇ／ｍｍ^２に達するのに対して、ステンレス鋼のそれはＨｖ〜２００Ｋｇ／ｍｍ^２程度に過ぎない。すなわち本発明の金属間化合物砥石の硬度はステンレス鋼の２．５〜５倍に達する。
また、本発明の金属間化合物砥石は高温になっても硬さの減少が少なく、約６００°Ｃまでは温度上昇と共に強度が上昇するという優れた性質を持っている。
本発明のダイヤモンド研磨用砥石において、さらに重要なことは、ダイヤモンドに対して驚くほど大きな耐摩耗性を示すことである。これは硬さがはるかに大きい超硬合金（ＷＣ＋１６％Ｃｏ：Ｈｖ〜１５００Ｋｇ／ｍｍ^２）よりも少ない摩擦減量を示すことからも容易に理解できる。
この砥石の大きな耐磨耗性は、数値制御機構を有する加工装置での研磨加工の形状精度維持には不可欠である。
【００２５】
上記のような、ダイヤモンドの薄膜の製造工程において、特に厚いダイヤモンドの膜を形成する場合には、ダイヤモンドの結晶粒が粗大化し、かつ結晶表面の凹凸が激しくなって研磨が著しく困難となるが、本発明の研磨加工方法を使用して１００〜８００℃に加熱しながら研磨加工することにより、このような難研磨加工性のダイヤモンドも砥石の破壊や極端な磨耗を発生することなく数値制御加工装置を用いて高い形状精度で研磨加工ができるようになった。
さらに、上記温度範囲への加熱により、合金砥石の結晶粒界が強化され、粒界割れが起こりにくくなることが確認された。
ダイヤモンドと砥石の接触点では、摩擦熱と外部加熱により、炭化物、炭窒化物の生成による化学的研磨が強く起こり、より効果的なダイヤモンドの研磨が進行しているものと推測される。
【００２６】
本発明の数値制御機構を有する加工装置で前記構成からなる砥石を用いた研磨加工の著しい特徴を利用して、他のダイヤモンド研磨砥石の一部にこの砥石を利用して、数値制御により研磨加工を行うことも当然可能である。本発明はこのような使用の全てを包含するものである。
単体の金属間化合物からなるダイヤモンド研磨用砥石を製造しようとする場合、金属間化合物以外の成分として、該金属間化合物の個々の成分元素が単体として存在したり、又は微量の不純物が混入する場合がある。しかし、この場合、砥石の中に本発明の金属間化合物が９０体積％以上含有量していれば、砥石としての機能を十分に発揮させることができる。
なお、本発明の砥石は、後述するように金属間化合物を構成する元素（金属）又は該金属間化合物を構成する金属以外の金属若しくは合金、又は超硬合金、半金属元素、非金属元素、セラミックス（含むガラス）、ダイヤモンド砥粒、有機化合物（ポリマー）等と複合又は混合させて使用することができる。
したがって、上記９０体積％以上の金属間化合物は、これを単体として砥石に使用する場合の好適な例を示しているだけで、本発明の砥石等は、上記の割合に制限されるものではない。
【００２７】
例えば、本発明の金属間化合物からなるダイヤモンド研磨加工用砥石の強度又は靭性等を増し数値制御による研磨加工の形状精度を向上させるために、金属間化合物を構成する主たる元素であるＡｌ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｒｕ、Ｒｈ、Ｐｄ、Ｏｓ、Ｉｒ、Ｐｔの群から選択した１種または２種以上の元素又はこれら以外の元素をさらに付加的に添加することができる。
金属間化合物の種類によっては、それ単独では脆すぎて砥石に出来ない場合がある。しかし、上記のように強度又は靭性を向上できる材料と組み合わせることにより、また他の金属間化合物との複合金属間化合物とすることにより、強度を通じて数値制御による研磨加工の形状精度を向上させることができる。したがって、単独では砥石にできない場合でも、上記のようにすることにより、数値制御により研磨加工の形状精度を向上できる砥石として使用することが可能であり、本発明はこのような砥石を用いたあらゆる場合をも包含する。
また、ダイヤモンド研磨加工用砥石の硬さを向上させ数値制御により研磨加工の形状精度を向上させるため、セラミックス又は超硬合金等を添加することもできる。本発明はこれら全てを包含する。
また、ダイヤモンド研磨加工用砥石の一部または全部を前記金属間化合物として研磨加工を実施するものであり、これによって、研磨加工機能を向上させることもできる。例えば、従来のダイヤモンド砥石と同様にダイヤモンド砥粒を金属間化合物で胆持した複合粒子を含む砥石は、過酷な研磨加工条件で砥石形状精度を維持するのに有効である。
また、本発明の金属間化合物とセラミックスとの複合砥石、金属間化合物を砥粒とした同金属間化合物と金属又は超硬工具材料との複合砥石、並びにこれらの複合体を場合によっては数値制御による本研磨加工に使用できる。
なお、上記の通り、複合砥石又は混合砥石とする場合、これらの材料の配合割合（体積率）や結合剤等の体積率等は加工目的や用途に応じて任意に選択できるものであり、特に制限されない。また、従来の砥石セグメントの一部に、上記の砥石を併用することもできる。これらは全て本発明に含まれるものである。
【００２８】
本発明の方法により優れた鏡面で、形状精度の高いダイヤモンド、特に、単結晶ダイヤモンドは高性能ダイヤモンド単石ドレッサー、高熱伝導ヒートシンクや新しい応用が期待できる３次元段差を有する高精度立体形状デバイスなどに、また、ダイヤモンド燒結体では超精密なダイヤモンド燒結体加工工具または超精密な金型部品、あるいは耐磨耗性精密３次元機構部品として、さらに本発明の方法により得られたダイヤモンド薄膜又はダイヤモンド自立体は、回路基板、高周波デバイス、ヒートシンク、精密非球面形状を含む各種光学素子、表面弾性波素子（フィルター）、平面ディスプレー、半導体や放射線センサー等の電子デバイス部品、超精密・ロングライフの機械部品あるいは計測用原器、あるいは各種摺動部品等に好適であり、飛躍的な新しい用途の拡大を具体化する上で
効果が著しい。
【００２９】
【実施例および比較例】
次に、本発明を実施例および比較例に基づいて説明する。なお、本実施例は好適な例を示し、かつ発明の理解を容易にするためのものであり、これらの例によって本発明が制限されるものではない。すなわち、本発明の技術思想の範囲における他の態様および例は、当然本発明に含まれるものである。
【００３０】
（実施例１）
Ｔｉ−Ｃｏ金属間化合物砥石を上記条件で製造し、外径１００ｍｍｘ内径８０ｍｍｘ厚み４．５ｍｍのリング状分割砥石を成形した。これらのリング状分割砥石を外径１００ｍｍｘ内径８０ｍｍｘ深さ４ｍｍの溝付円盤状ホルダー（直径１２０ｍｍ）に固定して研磨加工用のカップ状砥石とした。
本実施例では、リング状分割砥石を用いたが、ペレット状の円板を円周状に配列、固定する方法でも同様のカップ砥石が得られる。被研磨加工体としては３５ｍｍ角ｘ厚み５ｍｍの平板Ｓｉ基板上に５０μｍ膜厚みでマイクロ波ＣＶＤ法で成膜した気相合成ダイヤモンド膜、幅１０ｍｍｘ厚み２ｍｍのＷＣ−Ｃｏ超硬基板上に超高圧下で１ｍｍ厚みで燒結合成したダイヤモンド燒結体、３ｍｍカクｘ１ｍｍ厚みの（１００）面が端面のダイヤモンド並びに立方晶窒化ホウ素単結晶をそれぞれを用いた。
前記カップ型金属間化合物砥石は数値制御（ＮＣ）フライス盤のスピンドル軸に、被研磨加工体はテーブル上のバイス或いはホルダーに固定して室温にて研磨加工を行った。
砥石回転速度は、３２５−１，０００−ｒｐｍ、砥石切込み量は１μｍ−２０μｍ／加工パス、被研磨加工体を固定したテーブルの送り速度は砥石１回転当たり１２μｍとした。
図１に、気相合成ダイヤモンド膜での本砥石の加工能力を示す研磨結果を示す。図１は砥石切込み５μｍにて１パス研磨加工後の気相合成ダイヤモンド薄膜表面の微分干渉顕微鏡写真（倍率ｘ１００）である。１加工パスという短時間の加工で成膜時の表面凹凸はほとんどなくなり極めて高い研磨能力を示すことがわかる。
基板端部にはプラズマが集中しやすいため成膜後すなわち研磨加工前の膜厚みは基板端部で厚く中央部では薄い凹型形状をとっているにも係わらず１パス研磨加工でも平滑で表面うねりの少ない研磨加工が可能である。
特に端部では従来のダイヤモンド砥石研磨加工法と比較すると、端部のだれはほとんどないことがわかった。ダイヤモンド燒結体についても同様な結果が得られた。
大型ダイヤモンド単結晶は超高圧下で育成するため大変高価である。従って研磨加工による取代は最小化できることが好ましく、端部で発生するダレも著しく低減する必要がある。
本課題を克服するため特に軸偏心した棒状砥石を作製し、砥石先端を線接触となるよう曲面成形して研磨加工を実施した。特に端部のダレ防止のために砥石の研磨加工軌跡はＮＣフライス盤に連結したＣＡＭにより制御して被研磨加工体端部の研磨精度を向上させた。
得られた単結晶端部のダレは０．５μｍ以下に大幅に改善された。特に（１１１）面を端面とする結晶では、本数値制御研磨加工による端面ダレの改善効果は著しいことが明らかとなった。
特に本加工法すなわち本金属間化合物砥石と数値制御加工装置の組み合わせで得られる加工法並びに得られる加工体の注目すべき特徴について詳述する。本発明の加工法においては、金属間化合物砥石は高精度ツルーイングが可能であり（ダイヤモンド砥石では、精度の高いツルーイングは出来ていない。）、砥石形状精度の向上、高い砥石加工能力により加工装置の精度限界にせまる微小切込みでの工業的な研磨加工を実現し（ダイヤモンド被研磨加工体の加工中の破壊確率の著しい低下にも寄与）、従来にない高精度加工が可能となった。
従来のダイヤモンド砥石を用いた共削り加工では、加工の進行とともに砥石の加工能力は低下するため、数値制御を用いても再現性が高く、高い精度で工業的な自動加工はほとんど不可能であつた。
すなわち、ダイヤモンド砥石によるダイヤモンド薄膜、ダイヤモンド単結晶、ダイヤモンド焼結体等の研磨加工では、唯一の研磨加工法は、定荷重下で時間をかけて加工する所謂ラップ加工であり、経済性を考慮した手法では、切込みを微小に数値制御した加工手法は実現してない。
ダイヤモンド砥石の加工能力の低下に起因して、ダイヤモンド膜、単結晶、焼結体共に加工中に破壊確率が上昇するが、破壊を免れた場合でも研削抵抗の増加に伴い砥石にブレが発生し、膜面の平坦度、うねりについてはもっとも良好な場合でも０．０５μｍ、エッチ部のダレは数μｍが限界であり、被加工体ごとに加工精度は変動することが不可避であった。
本加工法では砥石の高い加工能力と最適値に設定された砥石回転数、砥石切込み量、被加工体固定テーブルの送り速度等により、膜面の平坦度、うねりについては＜０．０２μｍ、エッチ部のダレは＜１μｍに再現性良く制御研磨加工できることが明らかとなった。
上記被研磨加工体の本砥石による別の定切り込み加工例として、数値制御（ＮＣ）旋盤を用いた室温加工を実施した。上記ツルーイング成形したカップ砥石を旋盤回転軸にチャック固定し、被研磨加工体は工具台に取り付けた先端部に固定用溝がもうけた固定冶具に装着して平面研磨加工を実施した。
被研磨加工体としては１５ｍｍカクｘ厚み５ｍｍの窒化珪素基板に２５μｍ厚みでダイヤモンド膜を成膜したものを用いた。砥石回転数は１，０００ｒｐｍとし、砥石切込み量は、３μｍ／加工パス、被加工体の送り速度は砥石１回転当たり２０μｍとした。ＮＣフライス盤の加工結果と同様に、優れた加工品質とその再現性が確認できた。
【００３１】
（実施例２）
次に、Ｚｒ−Ａｌ金属間化合物砥石を上記条件で製造し、直径２０ｍｍｘ厚み５ｍｍのペレット状軸付砥石を作製した。砥石外周部は被研磨加工体との線接触加工を確保するため曲面成形を行った。被研磨加工体は以下の方法で準備した。
直径３５ｍｍで片側端面が曲率半径１００ｍｍの凸形状を有するペレット状窒化珪素セラミックス基板を準備し、この凸状３次元端面に熱フィラメント法で膜厚み２０μｍのダイヤモンド膜を成膜した。
３次元形状を有する凸状ダイヤモンド成膜面をダイヤモンド膜の厚みが一定となるように研磨加工を実施するには、被研磨体の最終寸法形状諸元にならって切込み量を微小に制御しつつ砥石の最適研磨加工軌跡を数値制御できる研磨加工手法が不可欠である。
この課題を実現する手法として本実施例では、数値制御加工システム・装置としてＣＡＭに接続したＣＮＣグラインディングセンターを使用した。砥石回転数は、１０，０００ｒｐｍであり研磨加工は室温で実施した。
図２には、未研磨加工部／研磨加工部境界の電子顕微鏡写真（倍率ｘ５００）をしめす。適正な研磨加工条件の設定により砥石の１パス研磨加工でも優れた鏡面が得られることがわかる。
実施例１に詳細に述べたように、本砥石の研磨加工能力は極めて高いため、ＣＡＭプログラムに従い３次元凸形状を研磨加工中砥石の軸ぶれはほとんど発生しない。従ってμｍレベルの微小切込みを可能とし、数値制御による形状精度の極めて高い研磨加工が可能となった。
研磨加工面は、鏡面であり、表面粗さも０．０５μｍ以下の良好な研磨結果がえられた。研磨形状・寸法精度も加工装置精度にせまり、ＣＡＭプログラムからの寸法ずれはほとんど認められなかった。
Ｘ線を用いた非破壊計測法で研磨加工後のダイヤモンド膜厚みの場所による変動を調査したが、優れた研磨加工精度に示すように膜厚みはすこぶる均一であることが確認できた。同様の研磨加工をダイヤモンド燒結体についても実施した。
研磨加工用サンプルは直径３５ｍｍ、厚み２ｍｍの超硬板に厚み１ｍｍ弱の燒結体層を設けたものである。凸形状の曲率半径は２００ｍｍである。ダイヤモンド膜の場合と同様に優れた形状精度を有する３次元鏡面研磨が可能であることが明らかとなった。
前記したようにダイヤモンド膜の研磨加工手法としては“共削り”によるダイヤモンド砥石法が用いられてきた。この研磨加工法では、加工中に砥石研削抵抗が上昇することは避けられず、砥石の軸ぶれ等の理由からμｍレベルの微小切込みと数値制御による寸法・形状精度の高い３次元形状研磨加工は不可能とされてきた。
しかし、本研磨加工手法が実現したことにより、微細な表面凹凸を有する平板状ダイヤモンド膜体からでも寸法・形状精度が高く、鏡面を有する３次元形状ダイヤモンド膜体を再現性よく研磨加工することが可能となった。
【００３２】
（実施例３）
Ｚｒ−Ａｌ金属間化合物砥石のかわりにＴｉ−Ｆｅ金属間化合物砥石を製造して研磨加工を実施した。被研磨加工体は直径３５ｍｍｘ厚み５ｍｍ炭化珪素セラミックス平板上に周囲に平坦部を残し、曲率半径５０ｍｍの凹型形状を作製（平坦面との接線部では、形状をなめらかとするため適度の逃げを設けている。）、この平面、凹面の組み合わせからなる３次元形状基板面に熱フィラメント法で膜厚み２０μｍのダイヤモンド膜を成膜した。研磨加工は同様に室温にて実施した。
数値制御システム・加工装置としては、ＣＡＤ／ＣＡＭに接続したＣＮＣマシニングセンターを用いた。自在形状のダイヤモンド膜面を砥石の最適研磨加工軌跡で研磨するにはＣＡＤ／ＣＡＭによるコンピュータ制御が極めて有効である。
あらかじめ被研磨加工体面の形状・寸法をＣＡＤにて設計、プログラム化し、ＣＡＭにて砥石の最適研磨加工軌跡を指定、数値制御研磨加工を実施する。（このＣＡＤ設計、ＣＡＭを用いた数値制御加工によりダイヤモンド成膜基板は形状加工が施され準備される。）
砥石は、加工中被加工体と線接触加工となるよう先端部を一定の曲率に成形し、回転軸より軸偏心させた棒状体とした。砥石回転数は、１２，０００ｒｐｍ、とし、被研磨加工体も２００ｒｐｍで回転した。砥石切込み量は１μｍ／加工パス、砥石送り速度は１０μｍとし円弧研磨加工を実施した。
実施例２と同様に研磨加工施した３次元形状ダイヤモンド膜面は鏡面であり、形状・寸法精度も極めて良好であった。
【００３３】
（実施例４）
次にＨｆ−Ｃｏ金属間化合物砥石を上記条件で製造し、直径１０ｍｍｘ厚み５ｍｍのペレット状軸付砥石を作製した。
被研磨加工体としては、外径２５ｍｍｘ内径１５ｍｍｘ長さ２５ｍｍの超硬製円筒の面に熱フィラメント法でダイヤモンド膜を２０μｍ成膜したものを用いた。
数値制御加工装置としては、縦型ＮＣフライス盤を使用した。砥石回転速度は、１０，０００ｒｐｍとし、被研磨加工体は回転テーブルに取り付けて１００ｒｐｍの回転速度で砥石とは逆回転してコンタリング研磨加工を実施した。砥石切込み量は２−１０μｍとし、Ｚ方向送り速度は、０．０１−０．５ｍｍ／ｍｉｎ．とした。
得られた研磨面は良好な鏡面であり、真円度も２μｍで形状・寸法精度も金属加工並みの研磨が実現した。
【００３４】
（実施例５）
実施例２−４の成果を元に、より複雑な３次元形状として超硬ダイヤモンド被膜処理を施した超硬製の２枚刃ソリッドエンドミルの底刃並びにサイド（外周）刃を研磨加工した。使用した数値制御加工装置はＮＣ工具研削盤である。
研磨加工用砥石としてはＮｂ−Ｃｏ金属間化合物を用い、１００ｍｍ径のセグメント式平砥石並びにカップ砥石を作製して研磨加工を実施した。
研磨加工後のダイヤモンド被膜面はすこぶる良好な鏡面となり、Ａｌ−Ｓｉ合金を用いた切れ味、耐久性等加工テスト評価結果は、
研磨加工処理ダイヤモンド被覆エンドミル》
ダイヤモンド被膜まま品》
超硬製エンドミル
の順であり、ダイヤモンド被膜に鏡面研磨加工を施こすことによりエンドミルの加工精度、耐久性とも圧倒的に向上することが証明された。
エンドミルに代表される３次元形状ダイヤモンド被覆体にて研磨加工を実施、研磨加工の工具性能への効果を把握した事例は本発明が最初であり、数値制御加工装置を用いた本砥石研磨手法により始めて実現したものである。
比較例として、同様な形状のダイヤモンド砥石を用いて２枚刃ソリッドエンドミルの底刃並びにサイド（外周）刃の数値制御研磨加工を試みた。研削抵抗の著しい上昇により被膜の剥離、ダイヤモンド砥石が破壊する場合がほとんどであり、研磨負荷を低減すると砥石は空すべりするため事実上研磨加工は不可能であった。
【００３５】
（実施例６）
次に本発明の実施例１の金属間化合物砥石にダイヤモンド砥粒を混合し、金属間化合物／ダイヤモンド複合粒子入り砥石を作製し、これを用いて実施例１と同様な研磨加工を実施した。
ダイヤモンド砥粒は、＃４０００を使用し、体積％にて５％を添加した。ダイヤモンド粒子の複合により、研磨加工による砥石の磨耗減量は一層低下して、砥石の初期形状の安定化を通じて高精度研磨加工に大きな効果を示すことが明らかとなった。
【００３６】
実施例の殆どは、常温で数値制御により研磨加工を実施した例を示したが、上記の通り適時加熱して研磨加工することができる。この加熱により研磨能率は一層向上する。しかし、特に研磨加工体の形状精度が厳しく要求される場合には、加工装置本来の極限精度で研磨加工を実施することが好ましく又は被研磨加工材により加熱が望ましくない場合には、室温（常温）で実施することができる。
本発明の数値制御研磨加工法に用いる砥石は、成分調整が容易で、偏析がなく、また、粗大結晶を生じないという理由から粉末冶金によって製造するのが良いが、製造の容易性から溶製法を用いることもできる。この砥石の製造法は、特に制限されるものではなく、用途に応じて適時選択できる。
上記実施例においては、比較的簡単な成分組成砥石を使用した場合を例示したが、金属間化合物以外に、ダイヤモンド、金属単体を含ませた（複合させた）砥石を使用することもできるし、また、セラミックスを複合させた砥石、ダイヤモンド砥石をセグメントとして併用した砥石も数値制御研磨加工にて使用できる。砥石としての機能を備えかつ砥石の一部に研磨加工能力が極めて高い本砥石を使用したものは、全て本発明に含まれるものである。
また、本発明の数値制御研磨加工法の実施例では、数値制御加工装置として
幾つかの加工装置を例示したが、用途、目的に応じて適時選択できるものであり、必ずしも本実施例に限定されるものではない。同様に研磨加工の仕様に応じて併用される各種付帯設備も同様に適時選択できるものである。
特に３次元で高い形状精度が要求される研磨加工時に威力を発揮する、ＣＡＭプログラム、ＣＡＤとＣＡＭプログラムについても特に本実施例に限定されるものではなく、本発明の目的に沿うものであれば、全て本発明に含まれるものである。
【００３７】
【発明の効果】
以上、本発明は、数値制御機構を有する加工装置を用いて、主成分としてＴｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｍｏ、Ｔａ、Ｗの群から選択した１種若しくは２種以上の元素粉末とＡｌ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｒｕ、Ｒｈ、Ｐｄ、Ｏｓ、Ｉｒ、Ｐｔの群から選択した１種若しくは２種以上の元素粉末を、それぞれ本発明の金属間化合物が形成できる組成及び比率に調合した砥石または前記砥石に所定の量複合粒子を含有する砥石を使用し、一定圧力または一定切込み条件で被研磨加工体であるダイヤモンド薄膜、ダイヤモンド単結晶、ダイヤモンド燒結体等に対して相対的に動かし、或いは砥石と被加工体が相対運動するように動かすことにより前記ダイヤモンドに押し当てて研磨加工することで、鏡面で、かつ、うねり、端部のだれ等の極めて少ない高い形状精度を有し、高い再現性と研磨加工能率を低コストで実現できる研磨加工方法、また、従来法では事実上研磨加工が不可能であった高精度３次元形状研磨加工を可能にするという優れた効果を有する。
また、ＣＡＭ、またはＣＡＤとＣＡＭプログラムで複雑形状の研磨加工を自動化し、
従来の研磨加工法では高い熟練技術を必要とした高精度研磨加工も大幅にコストダウンがはかれ、従来にない高い形状精度の新しい各種応用製品を提供することで各種産業に多大の波及効果をもたらすことのできるという際立った特長を有する。
【図面の簡単な説明】
【図１】Ｔｉ−Ａｌ金属間化合物砥石を使用して砥石切込み５μｍにて１パス研磨加工後の気相合成ダイヤモンド薄膜表面の微分干渉顕微鏡写真（倍率ｘ１００）である。
【図２】Ｚｒ−Ａｌ金属間化合物砥石を用いて曲率半径１００ｍｍの凸状３次元曲面を１パス研磨加工した際の未研磨加工部／研磨加工部境界の電子顕微鏡写真（倍率ｘ５００）である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to polycrystalline diamond, diamond single crystal, diamond thin film (diamond formed on a substrate by vapor phase synthesis or free-standing film (including foil, flat plate, and three-dimensionally shaped body), diamond such as diamond sintered body, etc.). Using a processing machine with an excellent intermetallic compound grinding wheel and a numerical control mechanism for polishing itself or a material containing diamond, with a mirror surface, and undulation, extremely low shape accuracy such as edge droop, A polishing method that can achieve high reproducibility and polishing efficiency and a polishing method were practically impossible.High precision Three Dimensional polishing method.
[0002]
[Prior art]
Today, a diamond thin film is attracting attention as one of materials using diamond. The diamond thin film is industrially (artificially) manufactured by a vapor phase synthesis method (CVD method) to produce a diamond thin film (a thin film formed on a substrate and a diamond film covering member) or a diamond free-standing film made of polycrystalline grains. However, the diamond thin film composed of a large number of crystal grains obtained by the above-mentioned synthesis method has a highly uneven surface.
For this reason, when a diamond thin film formed by a vapor phase synthesis method is used for an electronic component, an optical component, an ultra-precision component, a processing tool, or the like, a three-dimensional extremely high typified by an optical mirror or a milling tool. It is necessary to smooth the diamond surface while achieving shape accuracy.
[0003]
In addition, natural and artificial single-crystal diamonds (by ultra-high pressure synthesis, vapor phase synthesis, etc.) are used as various industrial products or jewelry such as dressers, blades, dies, heat sinks, X-ray windows, electronic component substrates for grinding wheels. However, finally, it is necessary to finish the shape accuracy to be applicable to each application.
Furthermore, the diamond sintered body using diamond, utilizing its properties, high-speed precision grinding or polishing of automobile engines, etc., tools for precision grinding or polishing of cemented carbide, cutting or cutting blades, wear-resistant mechanism It is becoming widespread for applications requiring high shape accuracy and extremely smooth surface finish (surface roughness), such as heat sinks or packages for communication equipment.
In addition, Co, WC, TiC and the like are used as a binder in the diamond sintered body, but there are also some that hardly contain or do not contain the binder. In the present invention, all of these sintered bodies are included unless otherwise specified.
[0004]
Diamond is a very hard substance that can be used for polishing other hard materials such as metals and ceramics or for fine polishing of jewelry.Be sure to polish diamond with high shape accuracy and a very smooth surface finish. It is easy for anyone to understand what is difficult.
As a method for smoothing such a vapor-phase synthetic diamond thin film, a polycrystalline diamond film or a self-solid body having a large number of irregularities, a tough cast iron plate is rotated at high speed and co-rubbed with diamond abrasive grains on a cast iron plate. The skif method of shaving / polishing is exemplified.
This method has been used for a long time for fine polishing of natural single crystal jewelry. However, as a method for polishing the diamond thin film or the like, the processing efficiency is extremely low, and the shape precision polishing processing on the order of μm is performed. It is almost useless because you cannot expect it.
[0005]
In particular, the diamond single crystal has a remarkable change in hardness depending on the crystal plane or crystal orientation, and the plane that can be lowered at present is limited to the (100) plane or the (110) plane, and the shape accuracy of the polished surface is also controlled. It is hard to say that it is polished.
Polishing of the (111) plane, which has the best hardness and thermal conductivity, is extremely difficult and is said to be practically impossible.
For this reason, when polishing a diamond single crystal, a highly skilled technique for polishing while examining the crystallographic plane and crystal orientation around the polished surface is required, which complicates the polishing of diamond. And the cost was high.
[0006]
In the polishing of a diamond sintered body, the difference in hardness between the diamond particles and the binder in the sintered body or the crystal plane and orientation of each diamond particle is determined by a polishing method using a diamond grindstone (co-shearing) as described later. Due to the difference in hardness based on the difference in the number of diamond particles in the sintered body during the polishing process, a large step (about several μm) is likely to occur due to the drop of diamond particles, and such a sintered body is used as a processing tool. In this case, there is a problem that the processing accuracy in the transfer processing is reduced due to the step, and that when used as a wear-resistant mechanism part, the friction characteristics are reduced.
In addition, since the diamond particles themselves in the sintered body are also damaged, they fall off during use and cause damage to themselves, causing a fatal trouble.
[0007]
As described above, since the hardness of diamond is such a hard material that there is no substitute, it is common to think that there is no other polishing material than diamond (co-shear). For this reason, as a method of smoothing a vapor-phase synthetic diamond thin film, a polycrystalline diamond film or a self-solid body having a large number of irregularities on its surface, particularly on a flat surface, a diamond grinding stone (co-shearing) polishing method can be mentioned.
A diamond grindstone is a resin-bonded grindstone that emphasizes sharpness by using a diamond grindstone having a high crushing property using a phenol resin as a binder and a diamond grindstone having a high friability as a binder. There are a metal bond grindstone, a vitrified (glass) bond grindstone and the like having a high abrasive grain strength and a high abrasive grain holding power, that is, a high tool rigidity.
In the polishing process of the present vapor-phase synthetic diamond thin film, polycrystalline diamond film, or self-solid, the surface of the material to be polished is an overwhelming number compared to the number of diamond abrasive grains (number of cutting edges) acting on the polishing process in the above-mentioned grindstone. It is a co-shearing process, in which the grinding mechanism is crushed and worn by the same hardness of the material, and the grinding speed is extremely low, but the grinding wheel wear is severe, so the shape precision is high. Polishing is difficult.
In addition, the fact that the grinding wheel rigidity is clearly lower than that of the material to be polished also causes a reduction in processing accuracy.
[0008]
One method for improving the polishing speed and shape accuracy is to use a metal bond whetstone that uses hard and high-rigidity cast iron as a binder. There is a polishing method in which the sharpening of the blade is electrochemically automated.
This method can be expected to improve polishing performance compared to the above method, but since the volume ratio of diamond abrasive grains that can be used is the same, to improve the polishing rate, a high load load on the grindstone is essential, There remains a dilemma that an expensive processing apparatus with higher rigidity and an improvement in grindstone rigidity are required to improve the shape accuracy.
[0009]
As a method other than the above, there has been proposed a method in which iron or stainless steel is pressed against diamond and polished. Although diamond is chemically stable at room temperature, it is graphitized when heated to 700 ° C. in air and starts burning, and becomes graphitized at 1400 ° C. or higher even in vacuum. The above method is a method of polishing using the reaction between iron and diamond at such a high temperature.
The reaction between iron and diamond (carbon in the diamond component dissolves in the metal) occurs at about 800 ° C.₃It is understood that C (cementite) is generated, this is peeled off on the friction surface during polishing, and the polishing proceeds further.
At a high temperature, this reaction proceeds more easily, and Fe₃Generation and decomposition of C occur, and polishing proceeds. It is said that a temperature of 900 ° C. or higher is necessary in consideration of the processing efficiency.
[0010]
This iron or iron-based material was considered to be a good method in that inexpensive abrasives could be used, but the main problem with this method was that effective polishing would not be possible without heating to high temperatures. is there.
However, stainless steel and iron-based materials soften at high temperatures and significantly decrease in strength.Besides the disadvantage that the grinding wheel cannot maintain the rigidity and shape accuracy during polishing, the grinding wheel with a high heat capacity contacts the workpiece to be polished. Therefore, there is a difficulty that it is practically impossible to perform dimensional accuracy polishing in which shape accuracy can be discussed due to fluctuations in thermal expansion or the like.
In particular, when high-temperature iron is used, it is necessary to perform polishing in a vacuum or in a reducing atmosphere in order to prevent oxidation of iron, so that the polishing operation is complicated also in terms of equipment (freely). There is also a problem in that it is not possible.
[0011]
Furthermore, the high-temperature heating described above also affects the diamond to be polished and the substrate material, causing cracks in the diamond due to the complex thermal stress caused by a sharp temperature gradient, and peeling of the diamond film from the substrate. And other problems.
In addition, laser processing in which a YAG laser is obliquely incident is conceivable, but the shape of the polished surface and the smooth surface finish accuracy (surface roughness) are inferior and cannot be used.
As mentioned above, using a grinding machine with excellent grinding ability and a processing device having a numerical control mechanism, with a mirror surface, and, with undulation, extremely low shape accuracy such as edge droop, high reproducibility and A polishing method capable of realizing a polishing efficiency, a high-precision three-dimensional shape polishing method that was practically impossible with the conventional method, and a mirror surface obtained by such a polishing method with high shape accuracy. Diamond polished bodies (including diamond thin films, polycrystalline diamonds, etc.), single crystal diamonds and sintered diamonds have not been obtained.
[0012]
[Problems to be solved by the invention]
As described above, the present invention relates to a diamond single crystal, a diamond thin film (diamond or a diamond free-standing film (including a foil, a flat plate, and a three-dimensional shape) formed on a substrate by a vapor phase synthesis method), a diamond sintered body, and other various materials. A polishing method capable of realizing high reproducibility and polishing efficiency with extremely high shape accuracy such as crystal diamond, diamond itself or a material containing diamond with a mirror surface, and undulation, edge droop, etc. And a high-precision three-dimensional shape polishing method which cannot be polished by the conventional method, and a mirror-polished diamond polished body (diamond thin film, polycrystalline diamond) having a high surface accuracy obtained by such a polishing method Etc.), and to obtain a single crystal diamond and a diamond sintered body.
The present inventor has already made one or more elements selected from the group of Al, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Os, Ir, Pt, and Ti, Zr, A grindstone mainly composed of an intermetallic compound with one or more elements selected from the group consisting of Hf, V, Nb, Mo, Ta, and W, or an excellent wheel containing a predetermined amount of composite particles in the grindstone (Japanese Patent Application Nos. 11-130991, 11-218850, 11-320523, and 2000-12479).
The present invention further develops these, and provides a polishing method which has high shape accuracy on a mirror surface, excellent in reproducibility and polishing efficiency, and a high precision 3 which was practically impossible in the conventional method. Provided are a three-dimensional shape polishing method, a diamond-polished body (including diamond thin film, polycrystalline diamond, etc.), a single crystal diamond, and a diamond sintered body having a mirror surface and high shape accuracy obtained by such a polishing method. It is.
[0013]
[Means for Solving the Problems]
The present invention
1. Using a processing device having a numerical control mechanism, one or more elements selected from the group consisting of Al, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Os, Ir, and Pt. And a grindstone mainly containing an intermetallic compound of one or more elements selected from the group of Ti, Zr, Hf, V, Nb, Mo, Ta, and W or a grindstone containing composite particles in the grindstone A diamond thin film, a diamond single crystal, a diamond single crystal, a diamond single crystal, and a diamond single crystal, characterized in that the diamond thin film, diamond single crystal, diamond Numerical control polishing method for sintered body
2. 2. The numerically controlled polishing method as described in 1 above, wherein the polishing is performed by using a numerically controlled processing device controlled and driven by CAM (Computer Aided Machining) or CAD (Computer Aided Design) and a CAM program.
3. Polishing is performed by using a numerical control processing device capable of polishing a flat surface, a surface having a constant unevenness of curvature, a free-form surface, or the like, which can be formed by a combination of at least one selected from the group consisting of a flat surface, a convex surface, and a concave surface. Or the numerically controlled polishing method according to 2.
4. The numerical control polishing method according to any one of the above 1 to 3, wherein the workpiece is subjected to constant pressure or constant cutting by point contact, line contact or surface contact using a grinding wheel.
5. The composite particles contained in the processing whetstone are diamonds as described in any one of the above 1 to 4,Numerical control polishing method
Is to provide.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
The grinding wheel for diamond polishing of the present invention can be manufactured by, for example, powder metallurgy. In this case, one or more powders selected from the group consisting of Ti, Zr, Hf, V, Nb, Mo, Ta, and W each having an average particle size of 150 μm or less (preferably 10 μm or less) and Al, One or more powders selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Os, Ir, and Pt (hereinafter referred to as “grinding powder” unless otherwise specified) )) And the respective intermetallic compounds (hereinafter, unless otherwise specified, include “the content of the intermetallic compound is 90% by volume or more”). And the mixture is mixed in a ball mill and dried to obtain a mixed powder.
As the raw material powder, fine atomized powder can be used. It is also possible to use whetstone powder alloyed in advance at a predetermined ratio by a mechanical alloying method.
When a fine and uniform mixed powder is used, there is an advantage that the density of the sintered body is high, and as a result, a uniform and dense grindstone can be obtained.
These powders may be a single metal powder, a powder previously alloyed (intermetallic compound), or a composite powder thereof.
[0015]
Next, the mixed and crushed powder is put into a mold and preliminarily molded, for example, subjected to a cold isostatic pressure treatment (CIP treatment), and further subjected to 1000 to 1300 ° C. and a pressure of 500 kgf / cm.²Hot press sintering (HP treatment) or CIP treatment under the conditions described above, and then similarly at 1000 to 1300 ° C. and a pressure of 500 kgf / cm.²Under the above conditions, hot isostatic sintering (HIP treatment) is performed to obtain a sintered body having a high density (preferably a relative density of 99% or more).
The conditions such as the temperature and the pressure of the CIP processing, the HP processing, the HIP processing and the like are not limited to the above, and other conditions may be set in consideration of the type of the raw material or the density of the target sintered body.
Further, instead of the above-described CIP processing, HP processing, HIP processing, and the like, a method of filling a mixed powder in a graphite mold and heating it by pulse current while compressing the mixed powder between upper and lower punches (electrodes), A sintered body can be obtained by a pulse current sintering method. In this case, a dense and uniform sintered body can be obtained particularly when the above-mentioned mechanical alloy powder is used.
[0016]
The alloy whetstone containing the intermetallic compound of the present invention as a main component can also be manufactured by a melting method such as vacuum arc melting, plasma melting, electron beam melting, and induction melting. At the time of dissolution, gas, especially oxygen, is remarkably mixed, and since the above-mentioned elements forming an intermetallic compound such as aluminum and titanium have a strong bonding force with oxygen, they are dissolved in a vacuum or an inert gas. It is necessary.
In addition, cast products of alloy whetstones containing these intermetallic compounds as main components tend to have lower mechanical strength than sintered products, so that segregation and crystal grains do not occur during melting and solidification processes. , It is necessary to carry out the temperature control and manufacture.
Cut out the required grinding wheel shape from the sintered body or ingot obtained by the powder metallurgy method or smelting method, a processing device having a numerical control mechanism, also the shape of the workpiece to be polished, finishing to a shape suitable for polishing accuracy, And it is fixed with such components as the intermetallic compound whetstone holder and the like to obtain a whetstone tool for diamond polishing.
[0017]
As an example of the object to be polished, if a diamond thin film or a diamond self-solid is used, the diamond thin film or the diamond self-solid can be formed by a generally known vapor deposition method (CVD method).
For example, a quartz tube which is open at a position near a tungsten filament heated to a high temperature (around 2000 ° C.) is arranged, and a mixed gas obtained by diluting a hydrocarbon gas such as methane with hydrogen is introduced through the quartz tube, and the temperature is 500 ° C. A method of decomposing and depositing diamond from the mixed gas on a substrate heated to １1100 ° C., a microwave plasma CVD method using a plasma discharge, an RF (high frequency) plasma CVD method, a DC ( Direct current) arc plasma jet method, or a method in which a flame of oxygen acetylene is applied to a substrate at high speed in the atmosphere to decompose and precipitate diamond from a hydrocarbon-containing gas.
The present invention can be applied to a diamond thin film or a diamond self-solid formed by these methods or other methods.
[0018]
By performing polishing with a processing device having a numerical control mechanism using the above-mentioned diamond grinding tool, natural diamond or artificial diamond can be mirror-finished, reproducibly and efficiently to a desired shape with high shape accuracy. Can be polished. In particular, although it is said that polishing of a diamond single crystal (111) surface is impossible with the prior art, according to the polishing method of the present invention, the (111) surface has a three-dimensional shape having a three-dimensional step on a mirror surface. It can be polished with high shape accuracy for devices, and new applications can be expected. Since the (111) plane can be polished, a high-quality (111) plane can be used as a rake face of a cutting tool, and a high-precision method using the (111) plane as a precision truer of a grindstone can be used. High performance and high value-added diamond single crystals such as single diamond dressers and high heat conductive heat sinks can be obtained.
[0019]
Similarly, when the object to be polished is a diamond sintered body, by performing the polishing with a processing device having a numerical control mechanism, the desired shape can be reproducibly and efficiently polished with extremely high shape accuracy.
Due to the difference in hardness between the diamond particles and the binder in the sintered body or the difference in hardness based on the difference in the crystal plane and orientation of each diamond particle, which is generated by the diamond grinding stone (co-shearing) polishing method. During polishing, a large step (about several μm) hardly occurs due to a large number of diamond particles falling out of the sintered body, and there is a problem of a decrease in processing accuracy in the transfer processing due to such a step. Also does not occur.
In addition, there is no problem in that the frictional characteristics tend to decrease when used as a wear-resistant mechanism part, and the application field is further expanded by obtaining a particularly high shape accuracy and an extremely smooth surface finish state.
[0020]
Examples of processing equipment having a numerical control mechanism include a honing grinder for a single-axis control machine, a CNC lathe, a CNC cylindrical grinder, and a CNC internal grinder for a two-axis control machine, and an NC milling machine and a CNC for a three-axis control machine. For turning lathes, CNC machining centers and CNC grinding centers, four-axis and five-axis control machines, for example, NC tool grinders, horizontal CNC machining centers, and machines with six-axis control or more, vertical and horizontal machining centers can be used as an example. It is clear that the present invention is not limited to a machine, and it is clear that various types of processing apparatuses can be used in combination depending on the purpose such as the shape of the object to be polished.
Also, by controlling and driving a processing apparatus having this numerical control mechanism with a CAM (Computer Aided Machining) or a CAD (Computer Aided Design), the workpiece to be polished is formed with a desired mirror surface, undulation, and edge. In order to obtain a very high shape accuracy with very little part drooping, the optimum grinding trajectory of the grindstone can be controlled with good reproducibility, and if it is controlled and driven by a CAD (Computer Aided Design) and a CAM program, the grinding method is practically impossible in the conventional method. Polishing processing of a high-precision three-dimensional shape, which was impossible, has been realized, and a high-performance diamond product having a complex free-form surface having high shape accuracy and an extremely smooth surface (surface roughness) can be provided.
[0021]
In addition, the grinding wheel for polishing is a complex free-form surface with excellent mirror surface and super-precision shape accuracy by having a shape and configuration that enables constant pressure or constant cutting by line contact and surface contact with the workpiece to be polished. Polishing is realized. If a line contact grindstone is used, the grinding resistance of the grindstone is extremely reduced, and in flat surface polishing, the sag at the end is improved by one digit or more in the conventional method. In addition, the polishing accuracy of a free-form surface and the like is dramatically improved.
In addition, in the case of a surface contact grindstone, the problem of waviness on a flat surface is extremely small, and highly accurate mirror polishing can be realized in a short time. Needless to say, the selection of a grindstone at the time of the polishing process can be appropriately selected according to the type and shape of the workpiece to be polished and the required polishing quality.
In the present polishing method, it is preferable to carry out a constant pressure or a constant cutting polishing in order to obtain high shape accuracy of the object to be polished. However, it is clear that the excellent grinding ability of the present grindstone can also be used in the so-called "lapping" machining method with a constant load grinding method used in the conventional method.
[0022]
When performing polishing using the grindstone having the above-mentioned configuration in the processing apparatus having the numerical control mechanism of the present invention, it is preferable to perform polishing at room temperature (normal temperature) from the viewpoint of achieving high shape accuracy. However, as described later, when the diamond has a large thickness and a large crystal grain (a case having a film thickness of several tens of μm or more and having a crystal grain of several tens of μm), polishing is performed while heating to 100 to 800 ° C. Is valid.
When the thickness of the diamond thin film or the like formed on the substrate as described above is small, for example, when the thickness is about 10 μm, the roughness of the diamond surface is about several μm, so that the polishing resistance is small and sufficient polishing can be performed even at room temperature.
At the contact point between the diamond and the grinding wheel, the frictional heat causes a local high temperature, but in such a situation, for example, the grinding wheel components of the present invention such as TiC, TiAlC, TiAlCN (Al, Cr, Mn, Fe, Brittle carbides, carbonitriding, etc. with Co, Ni, Cu, Ru, Rh, Pd, Os, Ir, Pt or Ti, Zr, Hf, V, Nb, Mo, Ta, W) are generated and peeled off. It is presumed that diamond polishing (chemical polishing) is progressing more effectively due to the above factors.
[0023]
On the other hand, in the case of thick film diamond, heating is effective from the viewpoint of polishing efficiency.
In this case, at the time of heating, at least a part of the grindstone and / or the portion to be polished is heated, and the polishing is performed by adjusting the temperature of the polishing section to 100 to 800 ° C.
If the temperature of external heating is lower than 100 ° C., the toughness of the alloy grindstone is inferior, and cracking of the grindstone is likely to occur. Also, the diamond itself receives substantially the same heating due to the above-mentioned heating and frictional heat. However, when the temperature exceeds 800 ° C., cracks or cracks often occur due to the thermal effect on the diamond or the like, and the diamond or the like is damaged. It must be avoided because it becomes easier. As the heating temperature, 300 to 500 ° C. is more preferable.
The total heat of external heating applied to the polishing section is adjusted so as to be within the above-mentioned temperature range. Although it is necessary to set the temperature in consideration of the temperature rise due to frictional heat, the temperature may suddenly exceed 800 ° C. due to frictional heat. The heating temperature set in the present invention does not include such a sudden temperature increase in the heating temperature of the present invention.
[0024]
The diamond polishing whetstone of the present invention is characterized in that its hardness at room temperature is extremely large as compared with stainless steel. The hardness of the intermetallic compound grindstone of the present invention obtained by the powder method is Hv500 to 1000 kg / mm.², Whereas that of stainless steel is Hv ~ 200 Kg / mm²Only about. That is, the hardness of the intermetallic compound grindstone of the present invention reaches 2.5 to 5 times that of stainless steel.
Further, the intermetallic compound grindstone of the present invention has an excellent property that the hardness decreases little even at a high temperature, and the strength increases with the temperature up to about 600 ° C.
More importantly, the diamond polishing wheel of the present invention exhibits surprisingly high wear resistance to diamond. This is a hard metal having a much higher hardness (WC + 16% Co: Hv〜1500 Kg / mm²It can be easily understood from the fact that the friction loss is smaller than that of ()).
The great abrasion resistance of the grindstone is indispensable for maintaining the shape accuracy of polishing in a processing apparatus having a numerical control mechanism.
[0025]
As described above, in the process of manufacturing a diamond thin film, particularly when a thick diamond film is formed, the crystal grains of the diamond become coarse, and the irregularities on the crystal surface become severe, and polishing becomes extremely difficult. By performing polishing while heating to 100 to 800 ° C. using the polishing method of the present invention, such a diamond having poor polishing properties can be numerically controlled without causing the grinding wheel to be broken or extremely worn. Polishing can be performed with high shape accuracy using.
Furthermore, it was confirmed that the heating to the above temperature range strengthened the crystal grain boundaries of the alloy whetstone and made it difficult for grain boundary cracks to occur.
At the point of contact between the diamond and the grindstone, it is presumed that due to frictional heat and external heating, chemical polishing due to generation of carbides and carbonitrides occurs strongly, and that more effective diamond polishing is in progress.
[0026]
Utilizing the remarkable feature of the polishing using the grindstone having the above-mentioned configuration in the machining apparatus having the numerical control mechanism of the present invention, utilizing this grindstone as a part of another diamond polishing grindstone, the polishing is performed by numerical control. It is of course possible to perform The present invention covers all such uses.
When attempting to manufacture a diamond polishing wheel made of a single intermetallic compound, as a component other than the intermetallic compound, individual component elements of the intermetallic compound are present as a simple substance, or when a trace amount of impurities are mixed There is. However, in this case, when the intermetallic compound of the present invention is contained in the grindstone at 90% by volume or more, the function as a grindstone can be sufficiently exhibited.
In addition, the grindstone of the present invention is, as described later, an element (metal) constituting the intermetallic compound or a metal or alloy other than the metal constituting the intermetallic compound, or a cemented carbide, a semimetal element, a nonmetal element, It can be used in combination with or mixed with ceramics (including glass), diamond abrasive grains, organic compounds (polymers) and the like.
Therefore, the above-mentioned 90% by volume or more intermetallic compound shows only a suitable example in the case of using it alone as a grindstone, and the grindstone of the present invention is not limited to the above ratio. .
[0027]
For example, in order to increase the strength or toughness of the grinding wheel for diamond polishing comprising the intermetallic compound of the present invention and to improve the shape accuracy of the polishing process by numerical control, Al, Cr, which is a main element constituting the intermetallic compound, One or more elements selected from the group consisting of Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Os, Ir, and Pt, or elements other than these can be further added.
Depending on the type of intermetallic compound, it may be too brittle alone to form a grindstone. However, by combining with a material capable of improving strength or toughness as described above, or by forming a composite intermetallic compound with another intermetallic compound, it is possible to improve the shape accuracy of polishing processing by numerical control through strength. it can. Therefore, even when it is not possible to use a grindstone by itself, it is possible to use it as a grindstone that can improve the shape accuracy of polishing by numerical control by performing the above, and the present invention The case is also included.
Further, in order to improve the hardness of the grinding wheel for diamond polishing and to improve the shape accuracy of the polishing by numerical control, ceramics or cemented carbide may be added. The present invention includes all of these.
In addition, a part or all of the grindstone for diamond polishing is used as the intermetallic compound to perform the polishing, whereby the polishing function can be improved. For example, like a conventional diamond grindstone, a grindstone containing composite particles in which diamond grains are supported by an intermetallic compound is effective in maintaining the grindstone shape accuracy under severe polishing processing conditions.
Further, a composite grindstone of the intermetallic compound of the present invention and ceramics, a composite grindstone of the same intermetallic compound using the intermetallic compound as abrasive grains and a metal or a cemented carbide tool material, and sometimes a numerical control of these composites Can be used for main polishing.
In addition, as described above, when a composite grindstone or a mixed grindstone is used, the mixing ratio (volume ratio) of these materials and the volume ratio of a binder and the like can be arbitrarily selected according to the processing purpose and application. Not restricted. Further, the above-mentioned grindstone can be used in combination with a part of the conventional grindstone segment. These are all included in the present invention.
[0028]
By the method of the present invention, a diamond with excellent mirror surface and high shape accuracy, in particular, a single crystal diamond can be used as a high-performance diamond single-stone dresser, a high heat conduction heat sink, or a high-precision three-dimensional device having a three-dimensional step where a new application can be expected. Further, in the case of the diamond sintered body, the diamond thin film or the diamond solid obtained by the method of the present invention is used as an ultra-precision diamond sintered tool or an ultra-precise mold part, or a wear-resistant precision three-dimensional mechanical part. Is used for circuit boards, high-frequency devices, heat sinks, various optical elements including precision aspherical shapes, surface acoustic wave elements (filters), planar displays, electronic device parts such as semiconductors and radiation sensors, ultra-precision and long-life mechanical parts or Suitable for measuring prototypes or various sliding parts, etc. In order to embody the expansion of the thermocline specific new applications
The effect is remarkable.
[0029]
[Examples and Comparative Examples]
Next, the present invention will be described based on examples and comparative examples. Note that the present embodiment shows a preferred example and is intended to facilitate understanding of the invention, and the present invention is not limited by these examples. That is, other embodiments and examples within the scope of the technical concept of the present invention are naturally included in the present invention.
[0030]
(Example 1)
A Ti-Co intermetallic compound grindstone was manufactured under the above conditions, and a ring-shaped split grindstone having an outer diameter of 100 mm x an inner diameter of 80 mm x a thickness of 4.5 mm was formed. These ring-shaped split whetstones were fixed to a grooved disk-shaped holder (120 mm in diameter) having an outer diameter of 100 mm x an inner diameter of 80 mm x a depth of 4 mm to obtain a cup-shaped whetstone for polishing.
In the present embodiment, a ring-shaped divided grindstone was used, but a similar cup grindstone can be obtained by a method of arranging and fixing pellet-shaped disks in a circumferential shape. As the object to be polished, a vapor-phase synthetic diamond film formed by a microwave CVD method with a film thickness of 50 μm on a flat Si substrate of 35 mm square × 5 mm thick, and super-deposited on a WC-Co carbide substrate of 10 mm wide × 2 mm thick. A diamond sintered body sintered and bonded to have a thickness of 1 mm under high pressure, a diamond having a (100) face having an end face of 3 mm kac x 1 mm and a cubic boron nitride single crystal were used.
The cup-type intermetallic compound grindstone was fixed to a spindle shaft of a numerically controlled (NC) milling machine, and the object to be polished was fixed to a vise or holder on a table and polished at room temperature.
The grindstone rotation speed was 325-1,000-rpm, the grindstone cutting amount was 1 μm-20 μm / working pass, and the feed speed of the table on which the object to be polished was fixed was 12 μm per revolution of the grindstone.
FIG. 1 shows a polishing result indicating the processing capability of the present grindstone with the vapor-phase synthetic diamond film. FIG. 1 is a differential interference micrograph (magnification x100) of the surface of a vapor-phase synthetic diamond thin film after one-pass polishing at a grinding wheel cut of 5 μm. It can be seen that the surface unevenness during film formation is almost eliminated by a short processing time of one processing pass, and an extremely high polishing ability is exhibited.
Since plasma tends to concentrate on the substrate edge, the film thickness after film formation, that is, before polishing is smooth at the substrate edge and thin at the center even in the one-pass polishing, but the surface is smooth and undulated. Polishing with less roughness is possible.
In particular, it has been found that there is almost no droop at the end as compared with the conventional diamond grinding method. Similar results were obtained for the sintered diamond.
Large diamond single crystals are very expensive because they grow under ultra-high pressure. Therefore, it is preferable that the machining allowance due to the polishing process can be minimized, and it is necessary to significantly reduce the sag generated at the end.
In order to overcome this problem, a rod-shaped grindstone with particularly eccentric shaft was prepared, and the grinding wheel was formed by forming a curved surface so that the tip of the grindstone was in linear contact. Particularly, in order to prevent the edge from sagging, the grinding trajectory of the grindstone is controlled by a CAM connected to an NC milling machine to improve the polishing accuracy of the edge of the workpiece to be polished.
The sag at the end of the obtained single crystal was greatly improved to 0.5 μm or less. In particular, in the case of a crystal having the (111) plane as an end face, it has been clarified that the effect of this numerically controlled polishing process on the sag of the end face is remarkable.
In particular, the working method, that is, the working method obtained by the combination of the present intermetallic compound grindstone and the numerical control processing device, and the remarkable features of the obtained work body will be described in detail. In the processing method of the present invention, the intermetallic compound grindstone is capable of high-precision truing (a diamond grindstone cannot perform high-precision truing). Industrial polishing with a small depth of cut, which is limited to the precision limit, has been realized (contributing to a significant reduction in the probability of breakage during the processing of the diamond-polished workpiece), and unprecedented high-precision processing has become possible.
In conventional co-machining using a diamond grindstone, the machining ability of the grindstone decreases with the progress of machining, so that even if numerical control is used, reproducibility is high and high-precision industrial automatic machining is almost impossible. Was.
In other words, in the polishing of a diamond thin film, a diamond single crystal, a diamond sintered body, and the like using a diamond whetstone, the only polishing method is a so-called lapping process in which processing is performed under constant load over a long period of time. In the method, a processing method in which the depth of cut is numerically controlled is not realized.
Due to the reduction in the processing ability of diamond grinding stones, the probability of breakage increases during processing of diamond films, single crystals, and sintered bodies, but even if the fractures are avoided, the grinding stones will shake due to the increase in grinding resistance. The flatness and undulation of the film surface are 0.05 μm even in the best case, and the sag of the etched portion is limited to several μm. Therefore, it is inevitable that the processing accuracy varies for each workpiece.
In this processing method, the flatness of the film surface and the waviness are <0.02 μm, and the etching is performed according to the high processing capability of the grinding wheel, the grinding wheel rotation speed set to the optimum value, the grinding wheel cutting amount, and the feed speed of the workpiece fixed table. It became clear that the sagging of the portion could be controlled and polished to <1 μm with good reproducibility.
As another example of the constant incision processing of the object to be polished by the main grindstone, room temperature processing using a numerical control (NC) lathe was performed. The truing-formed cup grindstone was chuck-fixed to a lathe rotating shaft, and the object to be polished was mounted on a fixing jig having a fixing groove at a tip end attached to a tool table, and planar polishing was performed.
As the object to be polished, a diamond film having a thickness of 25 μm was used on a silicon nitride substrate having a thickness of 15 mm and a thickness of 5 mm. The rotation speed of the grindstone was 1,000 rpm, the cutting depth of the grindstone was 3 μm / processing pass, and the feed speed of the workpiece was 20 μm per rotation of the grindstone. As with the processing results of the NC milling machine, excellent processing quality and its reproducibility were confirmed.
[0031]
(Example 2)
Next, a Zr-Al intermetallic compound grindstone was manufactured under the above conditions, and a pellet-shaped grindstone having a diameter of 20 mm and a thickness of 5 mm was prepared. The outer periphery of the grindstone was formed into a curved surface in order to secure line contact processing with the workpiece. The workpiece to be polished was prepared by the following method.
A pellet-shaped silicon nitride ceramics substrate having a diameter of 35 mm and a convex shape with one end face having a radius of curvature of 100 mm was prepared, and a diamond film having a film thickness of 20 μm was formed on the convex three-dimensional end face by a hot filament method.
In order to polish the convex diamond deposition surface having a three-dimensional shape so that the thickness of the diamond film is constant, it is necessary to finely control the cut amount according to the final dimensions and shape specifications of the object to be polished. A polishing method that can numerically control the optimal polishing trajectory of the grinding wheel is indispensable.
In this embodiment, a CNC grinding center connected to a CAM is used as a numerically controlled machining system / apparatus to achieve this object. The grindstone rotation speed was 10,000 rpm, and the polishing was performed at room temperature.
FIG. 2 shows an electron micrograph (magnification: 500) of the boundary between the unpolished portion and the polished portion. It can be seen that an excellent mirror surface can be obtained by one-pass polishing of a grindstone by setting appropriate polishing conditions.
As described in detail in the first embodiment, since the polishing ability of the present grindstone is extremely high, the wobbling of the grindstone hardly occurs during the polishing of the three-dimensional convex shape according to the CAM program. Therefore, it is possible to make a minute cut at a level of μm, and it is possible to perform polishing with extremely high shape accuracy by numerical control.
The polished surface was a mirror surface, and a good polishing result with a surface roughness of 0.05 μm or less was obtained. The polishing shape and dimensional accuracy were also limited to the processing device accuracy, and almost no dimensional deviation from the CAM program was recognized.
A non-destructive measurement method using X-rays was used to investigate the variation in the thickness of the diamond film after polishing, and it was confirmed that the film thickness was extremely uniform as shown by excellent polishing accuracy. The same polishing was performed on the sintered diamond.
The polishing sample is a superhard plate having a diameter of 35 mm and a thickness of 2 mm provided with a sintered layer having a thickness of less than 1 mm. The radius of curvature of the convex shape is 200 mm. It has been clarified that three-dimensional mirror polishing with excellent shape accuracy is possible as in the case of a diamond film.
As described above, a diamond grinding method based on "co-sharpening" has been used as a polishing method of a diamond film. In this polishing method, it is inevitable that the grinding wheel grinding resistance increases during the processing. For the reasons such as the wobbling of the grinding wheel, the 3D shape polishing with high dimensional / shape precision by micro incision at the micrometer level and numerical control is required. It has been impossible.
However, with the realization of this polishing method, it is possible to polish a three-dimensional diamond film having a mirror surface with high reproducibility, with high dimensional and shape accuracy even from a flat diamond film having fine surface irregularities. It has become possible.
[0032]
(Example 3)
Polishing was performed by manufacturing a Ti-Fe intermetallic compound grindstone instead of the Zr-Al intermetallic compound grindstone. The object to be polished leaves a flat part on the silicon carbide ceramics flat plate with a diameter of 35 mm and a thickness of 5 mm, and forms a concave shape with a radius of curvature of 50 mm (at a tangent portion with the flat surface, an appropriate relief is required to smooth the shape) A diamond film having a film thickness of 20 μm was formed by a hot filament method on the surface of a three-dimensional substrate having a combination of a flat surface and a concave surface. The polishing was performed at room temperature in the same manner.
A CNC machining center connected to CAD / CAM was used as a numerical control system / machining device. Computer control by CAD / CAM is extremely effective for polishing the diamond film surface of a free shape with the optimum polishing locus of the grindstone.
The shape and dimensions of the surface of the body to be polished are designed and programmed in advance by CAD, the optimal polishing trajectory of the grindstone is designated by CAM, and numerically controlled polishing is performed. (The diamond film formation substrate is subjected to shape processing and prepared by the CAD design and the numerical control processing using the CAM.)
The whetstone was formed into a rod-like body having a constant curvature at the tip end so as to perform line contact processing with the workpiece during processing, and being eccentric from the rotation axis. The rotation speed of the grindstone was 12,000 rpm, and the object to be polished was also rotated at 200 rpm. The grinding depth was set to 1 μm / processing pass, and the grinding wheel feed speed was set to 10 μm to perform the arc polishing.
The three-dimensional diamond film surface polished in the same manner as in Example 2 was a mirror surface, and the shape and dimensional accuracy were extremely good.
[0033]
(Example 4)
Next, an Hf-Co intermetallic compound grindstone was manufactured under the above conditions, and a pellet-shaped grindstone with a diameter of 10 mm and a thickness of 5 mm was produced.
As the workpiece to be polished, a diamond film having a thickness of 20 μm formed on a surface of a cemented carbide cylinder having an outer diameter of 25 mm × an inner diameter of 15 mm × a length of 25 mm by a hot filament method was used.
A vertical NC milling machine was used as the numerically controlled machining device. The rotation speed of the grindstone was 10,000 rpm, and the object to be polished was mounted on a rotary table, and rotated counterclockwise to the grindstone at a rotation speed of 100 rpm to perform contouring polishing. The cutting depth of the grindstone is 2-10 μm, and the feed speed in the Z direction is 0.01-0.5 mm / min. And
The obtained polished surface was a good mirror surface, the roundness was 2 μm, and the shape and dimensional accuracy were polished as well as metal processing.
[0034]
(Example 5)
Based on the results of Example 2-4, the bottom blade and the side (peripheral) blade of a two-blade solid end mill made of carbide and subjected to a carbide diamond coating treatment as a more complicated three-dimensional shape were polished. The numerically controlled machining device used was an NC tool grinder.
A Nb-Co intermetallic compound was used as a polishing grindstone, and a segment type flat grindstone and a cup grindstone having a diameter of 100 mm were prepared and polished.
The diamond coating surface after polishing becomes a very good mirror surface, and the processing test evaluation results such as sharpness and durability using Al-Si alloy are as follows.
Polished diamond coated end mill >>
Diamond coated product >>
Carbide end mill
It was proved that by subjecting the diamond coating to mirror polishing, the processing accuracy and durability of the end mill were significantly improved.
The present invention is the first case in which polishing was performed with a three-dimensional diamond coated body represented by an end mill and the effect of polishing on tool performance was grasped. It was realized for the first time.
As a comparative example, numerical control polishing of a bottom blade and a side (outer peripheral) blade of a two-blade solid end mill was attempted using a diamond grindstone having a similar shape. In most cases, the grinding resistance is remarkably increased, and the coating film is peeled off or the diamond grindstone is destroyed. When the grinding load is reduced, the grindstone slips and the polishing is practically impossible.
[0035]
(Example 6)
Next, diamond abrasive grains were mixed with the intermetallic compound grindstone of Example 1 of the present invention to produce a grindstone containing intermetallic compound / diamond composite particles, and the same polishing as in Example 1 was performed using this.
As the diamond abrasive, # 4000 was used, and 5% by volume was added. It became clear that the compounding of the diamond particles further reduced the wear loss of the grindstone by the polishing process, and showed a great effect on the high precision polishing process through stabilization of the initial shape of the grindstone.
[0036]
In most of the embodiments, the example in which the polishing is performed by the numerical control at room temperature is shown. However, the polishing can be performed by heating as appropriate as described above. The polishing efficiency is further improved by this heating. However, in particular, when the shape accuracy of the polished body is strictly required, it is preferable to perform the polishing with the ultimate accuracy inherent in the processing apparatus, or when heating is not desired due to the material to be polished, the room temperature (normal temperature). ).
The grindstone used in the numerically controlled polishing method of the present invention is preferably manufactured by powder metallurgy because the components are easily adjusted, there is no segregation, and no coarse crystals are formed. Can also be used. The method for producing the grinding stone is not particularly limited, and can be appropriately selected depending on the application.
In the above-described embodiment, a case where a relatively simple component composition whetstone is used is exemplified.In addition to the intermetallic compound, diamond and a whetstone containing a simple metal (composite) may be used, In addition, a grindstone using a composite of ceramics and a diamond grindstone as a segment can also be used in numerically controlled polishing. The present invention includes all whetstones which have a function as a whetstone and which use a whetstone having extremely high polishing ability as a part of the whetstone.
In the embodiment of the numerically controlled polishing method of the present invention,
Although some processing apparatuses are illustrated, they can be selected as appropriate according to the application and purpose, and are not necessarily limited to the present embodiment. Similarly, various auxiliary equipment used together according to the specifications of the polishing process can be similarly selected as appropriate.
In particular, the CAM program, CAD and CAM program, which are particularly effective in polishing processing requiring high three-dimensional shape accuracy, are not limited to the present embodiment. , Are all included in the present invention.
[0037]
【The invention's effect】
As described above, the present invention uses a processing apparatus having a numerical control mechanism to form one or more element powders selected from the group consisting of Ti, Zr, Hf, V, Nb, Mo, Ta, and W as main components. One or more element powders selected from the group consisting of Al, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Os, Ir, and Pt are formed by the intermetallic compound of the present invention. Using a grindstone adjusted to the composition and ratio that can be obtained or a grindstone containing a predetermined amount of composite particles in the grindstone, a diamond thin film, a diamond single crystal, a diamond sintered body, etc., to be polished under a constant pressure or a constant cutting condition. By moving the grindstone and the workpiece relative to each other, or by moving the grindstone and the workpiece relative to each other, by pressing against the diamond and polishing, the mirror surface, undulation, Polishing method that has extremely low profile accuracy, high reproducibility and polishing efficiency at low cost, and high-precision three-dimensional shape polishing that was virtually impossible with conventional methods. It has an excellent effect of enabling processing.
In addition, CAM or CAM or CAD and CAM programs automate the polishing of complex shapes,
With the conventional polishing method, high-precision polishing, which requires a high level of skill, is greatly reduced in cost, and by providing new applied products with unprecedented high shape accuracy, it has a great ripple effect on various industries. It has the distinctive feature of being able to bring.
[Brief description of the drawings]
FIG. 1 is a differential interference micrograph (magnification x100) of the surface of a vapor-phase synthetic diamond thin film after one-pass polishing at a grinding wheel cut of 5 μm using a Ti-Al intermetallic compound grinding wheel.
FIG. 2 is an electron micrograph (magnification: x500) of an unpolished / polished boundary when a convex three-dimensional curved surface having a radius of curvature of 100 mm is subjected to one-pass polishing using a Zr-Al intermetallic compound grindstone. is there.

Claims

Using a processing device having a numerical control mechanism, one or more elements selected from the group consisting of Al, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Os, Ir, and Pt. And a grindstone mainly containing an intermetallic compound of one or more elements selected from the group of Ti, Zr, Hf, V, Nb, Mo, Ta, and W or a grindstone containing composite particles in the grindstone A diamond thin film, a diamond single crystal, a diamond single crystal, a diamond single crystal, and a diamond single crystal, characterized in that the diamond thin film, diamond single crystal, diamond A numerically controlled polishing method for sintered bodies.

2. The method according to claim 1, wherein the polishing is performed by using a computer-aided machine (CAM) or a computer-aided design (CAD) and a numerically-controlled processing apparatus controlled and driven by a CAM program.

The polishing process is performed by using a numerical control processing device capable of polishing a flat surface, a surface having a constant curvature of irregularity, a free-form surface, and the like formed by at least one combination selected from the group consisting of a flat surface, a convex surface, and a concave surface. 3. The numerically controlled polishing method according to 1 or 2.

The numerically controlled polishing method according to any one of claims 1 to 3, wherein the workpiece is subjected to constant pressure or constant cutting by point contact, line contact or surface contact using a grinding wheel.

5. The method according to claim 1, wherein the composite particles contained in the grinding wheel are diamond.