JP2004017194A

JP2004017194A - Grinding device and method for automatically making grinding wheel approach work using the same

Info

Publication number: JP2004017194A
Application number: JP2002173842A
Authority: JP
Inventors: Akinori Yui; 由井　明紀; Shigeki Okuyama; 奥山　繁樹; Tomio Kubo; 久保　富美夫
Original assignee: Okamoto Machine Tool Works Ltd
Current assignee: Okamoto Machine Tool Works Ltd
Priority date: 2002-06-14
Filing date: 2002-06-14
Publication date: 2004-01-22

Abstract

<P>PROBLEM TO BE SOLVED: To make position adjustment in proximity to a cutting starting point of a grinding wheel automatically and in a short period of time by a non-contact sensing means. <P>SOLUTION: This device is provided with: a memory part ROM storing a counter "n" of grinding wheel lowering speed change (n=i-1), a reference electrical signal value U<SB>i</SB>for switching grinding wheel lowering speed S<SB>i</SB>to lowering speed S<SB>i+1</SB>and a reference electrical signal value U<SB>o</SB>for stopping lowering of the grinding wheel; a memory part RAM storing grinding wheel lowering speed S<SB>i</SB>, an electrical signal value Vi output from the non-contact sensor means; a comparator comparing the electrical signal value V<SB>i</SB>output by the non-contact sensor means and the reference electrical signal value U<SB>i</SB>; and a control unit part outputting the grinding wheel lowering speed S<SB>i+1</SB>switched after detecting the reference electrical signal value U<SB>i</SB>and a command to stop lowering of the grinding wheel. The grinding wheel lowering speed is automatically switched from high speed to low speed in sequence to make the grind wheel approach to the work automatically. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、ワ−クに対する砥石車の切り込み開始点を、砥石車の底部をワ−クに接することなく決める際に、砥石車をワ−ク表面に自動的に接近させる方法および該方法を実施する研削装置に関する。
【０００２】
【従来の技術】
金属、セラミック、シリコン基板等のワ−クをプランジ研削、トラバ−ス研削、平面加工成形、溝加工、切断する機械加工を行なうＮＣ研削装置は知られており（特開昭５５−８３５６７号、同５９−５９３４９号、同６１−１７３８５１号、特開平４−１３５５２号、特開２０００−１３５６７５号、同２０００−２７１８６６号、同２０００−３１７８２９号、同２００１−１７０８３２号、特許第２６９４１８９号、特許第３０２３０１８号）、また、岡本工作機械製作所、日立精工、ナガセインテグレックス、シギア（台湾）、Ｋｅｌｌｅｎｂｅｒｇｅｒ（スイス）、Ｊｏｎｅｓ　＆　Ｓｈｉｐｍａｎ　ＰＬＣ（英国）、Ｊｕｎｇ（ドイツ）、Ｔａｃｃｈｅｌｌａ　Ｍａｃｈｉｎｅ　Ｓ．ｐ．Ａ（イタリア）等より市販されている。
【０００３】
図８、図９および図１０に平面研削機械１の一例を示す。図中、２はワ−ク、３は左右方向（Ｘ軸方向）に往復移動可能なテ−ブル、４は電磁チャック、５は前後方向（Ｚ軸方向）に往復移動可能なサドル、６は砥石装置、７は砥石車を垂直方向（Ｙ軸方向）に移動する昇降機構を備えたコラム、８は砥石軸頭、９は砥石軸に備えられた砥石車、Ｍは砥石軸回転駆動モ−タ−、１０は操作盤、１１はベッド、１２は研削液供給ノズル、１３は制御ユニット部、１４は軸装置、１５はサ−ボモ−タである。
【０００４】
砥石軸頭８の鉛直方向（Ｙ軸方向）昇降動力は、サ−ボモ−タ１５から歯車１６、送りネジ１７、ネジ受け１８を介して砥石軸頭８に伝えられる。
テ−ブル３とワ−ク２との相対位置関数は既知とする（例えば、ハイデンハイン社のスケ−ルをテ−ブルに取り付け、テ−ブル上に取り付けたリミットスイッチにワ−ク左端が触れる位置をワ−ク基準原点とし、テ−ブル左端反転位置をテ−ブル原点とする。
【０００５】
１９は関数発生器、２０は研削量設定器、２１はパルス発生回路、２２は駆動回路である。
関数発生器１９には、予め研削量設定器２０（例えば対話型数値制御操作盤１０の操作キ−）により、研削すべきワ−ク形状に対応する関数式が設定されている。この関数式は変数として位置検出信号Ａを用いるものである。従って、関数発生器１９には入力される位置検出信号Ａに対応する研削量信号Ｂを演算し、連続的に出力する。
研削量信号Ｂは、次のパルス発生回路２１に与えられる。パルス発生回路２１は研削量信号Ｂを信号処理して制御パルス信号Ｃに変換し、駆動回路２２に出力する。
駆動回路２２は、現在のテ−ブル位置において研削すべき量に応じてサ−ボモ−タ１５を回転させる結果、砥石９は適性な高さ位置に設定される。
以上の動作は、操作盤１０からの運転指令により制御ユニット部１３を介して行われる。
【０００６】
この平面研削装置１では、テ−ブル３上のチャック４にワ−ク２を固定し、サドル５を移動させてＺ軸方向の位置を決め、テ−ブル３をＸ軸方向に往復移動させる過程で砥石軸頭８に備えられた回転している砥石車９をワ−ク２に接触させ、砥石軸頭をＹ軸方向にサ−ボモ−タ１５とボ−ルネジ１７で送りをかけてワ−クに切り込みをかけて研削する。この際、ワ−ク表面には研削液供給ノズル１２より研削液が供給される。
【０００７】
テ−ブル３の左右送りには、図示されていないが、サ−ボバルブ油圧シリンダ−駆動方式（特許第３０２３０１８号）、ボ−ルネジをサ−ボモ−タで駆動する方式、或いは、テ−ブルを直接リニアモ−タで駆動する方式が利用されている。
【０００８】
電動モ−タ−にて回転させた円盤状の砥石車をワ−ク（被加工物）の上方から所望の切り込み量の研削を行なう研削装置は、作業者が▲１▼砥石とワ−ク間の隙間の距離を見ながら手動パルス発生器に連結しているハンドルを回転しながらまたはジョグボタンを押しながら砥石車をワ−クに接近させ、▲２▼ついで、作業者が砥石車とワ−ク間の隙間の距離を見ながらハンドル１０ａを回転しながら前記工程の砥石車の下降速度よりは遅い速度で砥石車をワ−クに接近させ、▲３▼わずかな火花が飛んだ位置または研削液の変化した状態の位置を切り込み開始点と認識して行なっている。
【０００９】
この切り込み開始点位置の調整作業は、手動の研削装置は勿論のことＮＣ研削装置でも行われる。ＮＣ研削装置のときは、一度この作業をしてワ−クに対する砥石の切り込み開始点位置を決定すると、後はワ−クの加工を加工ソフトプログラムに従って自動で行なうことができる。同一寸法部品を繰り返し生産するときは、前加工寸法のばらつきを予め推測して加工点から一定量離れた安全な位置まで砥石車を高速で下降させて位置決めし、次に研削下降と同一条件で砥石車をワ−クに徐々に接近させ実研削加工に移るためエア−カット時間が長くなる。
この高速回転している砥石車をワ−クに近づける作業は熟練技能者にとっても容易ではなく、作業者の勘と経験に基づいて行なわざるを得ず、ワ−クの加工形状や材質によって条件が変わるため、また、砥石の外径が砥石の磨耗およびドレッシングにより時々刻々と変化するために熟練技能者の技が要求され、この技の習熟には長期間を要する。
【００１０】
また、この作業は、ワ−クに砥石車をおそるおそる接近させ、砥石車とワ−クの距離が遠いところを開始点として微細切り込みを開始すると長時間要する。逆に、砥石車を高速度でワ−クに接近させると砥石車がワ−クに激しく衝突して砥石車が破損したり、ワ−クに研削では除去できないダメ−ジを与えたりする。それゆえ、この砥石切り込み開始点の決定作業は作業者が一番嫌う作業であった。
【００１１】
非接触センサを用いてこの砥石切り込み開始点決定を自動化することが種々提案されている。例えば、実開昭６３−１１０３７１号公報はテ−ブル上に取り付けられたワ−クの上面と、回転する砥石車の加工面との距離を非接触で計測する距離センサを砥石車の安全保護カバ−に敷設した平面研削装置を、特開平６−５５４１４号公報は超音波センサを用いてワ−クと砥石間の位置を決定する方法を、特開２０００−３２６２２４号公報は空気圧力センサ（ＡＥセンサ）を用いて砥石車をワ−クへの切り込み開始位置へと接近させる方法を記載する。
【００１２】
更に、特開２０００−２６３４３６号公報は、レ−ザ光投光／受光端部と、受光量を表示する表示器を備えた増幅器とからなるカラ−識別センサ３００を図６に示す砥石車カバ−２３側面に備え付け、水平方向に移動可能なテ−ブル上に設置された磁気チャック４上に置かれたワ−ク２の表面に研削液をノズル１２より供給してワ−ク表面に研削液の薄膜を形成し、該薄膜の表面にカラ−識別センサ３００の光源から光を照射しつつ、かつ、その反射光を光ファイバ−に集光して光の色成分を認識してその値Ｅ_ｉを制御ユニット部１３の演算部に送信しつつ、ワ−ク表面に対し垂直方向に設けられた回転砥石車９をワ−ク表面に下降させ、回転する砥石車９がワ−クに近づくにつれてワ−ク表面に形成された液体の薄膜に空気が巻き込まれて細かい気泡を液体の薄膜内部に生じさせ、前記光の色成分の値Ｅ_ｉが予めＣＰＵの記憶部に気泡を内部に生じた研削液薄膜の光の色成分Ｅｏと一致した際の砥石のワ−クに対する位置を砥石の切り込み開始点とする方法を提供する。
【００１３】
また、特願２００１−１７６４０８号明細書は、図５に示すように研削装置の砥石９近傍に設置されたノズル１２より研削液を、テ−ブル上の磁気チャック４上に載置されたワ−ク２の加工点に向けてワ−ク２表面に供給しつつ、該ワ−ク表面に対して回転している砥石車９をワ−ク表面に下降させ、前記研削液を供給するノズル１２内に設置した水中マイクロホン３００が受波した研削液の音圧信号を所定の周波数帯域を通過させるバンドパスフィルタ３０７に通過させ、このバンドパスフィルタを通過した音圧信号より基本周波数を抽出し、該基本周波数における音圧信号の値（Ｐ_ｉ）が、予め設定した前記基本周波数における音圧信号の値（Ｐ_０）に達した（Ｐ_ｉ＝Ｐ_０）ときをワ−クに対する砥石の切り込み開始点と決定する方法を提案する。
【００１４】
これらレ−ザ光利用のカラ−識別センサ、カラ−識別センサに代えて距離デジタルレ−ザセンサ、或いは、超音波を利用した水中マイクロホン、空気圧力センサ等の電気信号を発するセンサ手段３００を備えた研削装置１は、非接触で砥石車とワ−ク間の距離を測定でき、砥石車のワ−クへの切り込み開始点の位置設定を自動的に行なえる利点を有するが、非接触で砥石車とワ−ク間の距離を電気信号で出力するため、一定速度で回転している砥石車９の下降速度が１００ｍｍ／分と大きいときは、ワ−ク上の研削液薄膜の厚みおよび気流の発生状態が一定でないゆえに出力されたデジタル電気信号（ｄｅｊｉｔ）の振れ幅が変化する。
【００１５】
図１１は、非接触センサとして、ワ−ク表面に投光されたレ−ザ光の反射光の受光量からワ−クまでの距離を測定する株式会社キ−エンスの長距離デジタルレ−ザセンサＬＶ−Ｈ３７（商品名）を用い、テ−ブルが停止している状態で１０リットル／分の研削油をワ−ク表面に供給しつつ、３２ｍ／秒で回転している砥石車を接近させた場合のワ−ク・砥石車間距離とデジタル電気信号トリガ値（レ−ザ散乱光強度）の相関図を示す。出力波形には相当量のノイズを含んでいる。
【００１６】
図４は、この長距離デジタルレ−ザセンサＬＶ−Ｈ３７（商品名）を用いて測定したときの、デジタルレ−ザセンサＬＶ−Ｈ３７が示すデジタル電気信号のトリガ−値とワ−ク砥石車間の距離を示すものである。
【００１７】
トリガレベル一定の場合、一定速度で回転している砥石車９の下降速度が１００ｍｍ／分と大きいときは、出力（ｄｅｊｉｔ）された電気信号Ｖ_ｉの振れ幅は大きく、０．３〜０．０４ｍｍの位置決め制度のばらつきがあり、下降速度が１０ｍｍ／分ではそのばらつきは０．０２ｍｍ程度になる。また、下降速度が速い場合には停止信号出力後の時間遅れに起因する砥石車移動量も大きくなり、オ−バ−シュ−ト発生のおそれもある。
【００１８】
砥石車９の下降速度が１００ｍｍ／分と大きいときは、砥石車のワ−クへの衝突を忌避するためには砥石車のワ−クへの接近距離が０．５ｍｍ近傍で停止する必要があり、手動に切替えて砥石車９の下降速度を遅くに切替えて手動で手パハンドルを回しながら残りの距離を下降させる。また、砥石車の下降速度を５ｍｍ／分と遅くすると砥石車９の低部をワ−ク表面０．０２ｍｍ近傍の切り込み開始点距離まで自動的に接近させることができるが、この距離に砥石車を接近させるに要する時間が長くなる欠点があった。
【００１９】
本発明者等は、一定速度で回転する砥石車９の下降速度を種々変えてワ−クに接近させた場合の出力信号Ｖ_ｉ（ｍＶ）と砥石車の底部とワ−ク表面間の距離Ｌ_ｉの相関を実測し、図４にその相関図を描いた。図４において、曲線もしくは折れ線はその出力信号Ｖ_ｉにおける砥石車の底部とワ−ク表面間の距離Ｌ_ｉの平均値を結んだもので、縦線はその出力信号Ｖ_ｉにおけるワ−ク表面間の距離の振れ幅Ｌ_ｉを示す。
【００２０】
前記図４は、砥石車９の下降速度の設定が１００ｍｍ／分のときは、出力信号値が１７０ｍＶであっても砥石車の底部とワ−ク表面間の距離は０．２６７ｍｍから−０．１２２ｍｍのいずれかであり、この値間０．３８９ｍｍの振れがあることを示唆する。
この下降速度で砥石車９を下降させて砥石車がワ−クに実際に接触した際（例えば砥石車とワ−ク間距離が−０．１２２ｍｍ）には、大きな火花が飛び散り、初心者の作業者はびっくりするであろう。即ち、砥石車とワ−クの実干渉が発生し、本発明の目的を達成しない。
【００２１】
設定する砥石車９の下降速度が小さくなるにつれ、この振れ幅は順次より小さくなる。砥石車９の下降速度の設定が７５ｍｍ／分のときは、出力信号値が１９０ｍＶであっても砥石車の底部とワ−ク表面間の距離は−０．０５ｍｍから＋０．１１ｍｍのいずれかであり、この値間０．１６ｍｍの振れである。砥石車９の下降速度の設定が５０ｍｍ／分のときは、出力信号値が２１０ｍＶであっても砥石車の底部とワ−ク表面間の距離は０．０２５ｍｍから０．１４５ｍｍのいずれかであり、この値間０．１２０ｍｍの振れである。砥石車９の下降速度の設定が２５ｍｍ／分のときは、出力信号値が２６０ｍＶであっても砥石車の底部とワ−ク表面間の距離は０．００５ｍｍから０．０６５ｍｍのいずれかであり、この値間０．０６０ｍｍの振れである。
【００２２】
更に、砥石車９の下降速度の設定が５ｍｍ／分のときは、出力信号値が３４０ｍＶであっても砥石車の底部とワ−ク表面間の距離は０．０１５ｍｍから０．０３５ｍｍのいずれかであり、この値間０．０２０ｍｍの振れであり、砥石車がワ−クに接触することはない。砥石車９の下降速度の設定が５ｍｍ／分のときで、出力信号値が３５０ｍＶのときは、砥石車の底部とワ−ク表面間の距離は−０．００５ｍｍから＋０．０２５ｍｍのいずれかであり、この値間０．０２０ｍｍの振れである。この下降速度５ｍｍ／分で砥石車９を下降させて出力信号値が３５０ｍＶとなって砥石車の下降を停止させた場合、砥石車がワ−クに実際に接触したとしても下降速度が遅いので火花の発生は無いか、あったとしても小さく、また、ワ−クが破損することはない。
【００２３】
【発明が解決しようとする課題】
本発明は、砥石車の研削面とワ−クの被研削面との間隔を非接触で検出できるセンサを用い、砥石切り込み開始点を決定する際に、短時間で砥石車をワ−ク近傍に接近する方法の提供および該非接触センサを用いた砥石車のワ−クへの接近方法を実施できる研削装置の提供を目的とする。
【００２４】
【課題を解決するための手段】
本発明の請求項１は、ワ−クを載せる水平方向に移動可能なテ−ブル、
前記テ−ブルの表面に対し垂直方向に昇降可能に設けられた円盤状の砥石車および該砥石車の昇降手段と回転駆動手段、
前記テ−ブル上に載せられたワ−クの表面に研削液を供給するノズル、
前記砥石車とワ−ク間の距離Ｌ_ｉを検出し、電気信号で出力する非接触センサ手段、
予め砥石車を一定速度で回転させつつ、砥石車を下降速度Ｓ_ｉで下降させてワ−クに接近させて測定した前記非接触センサ手段より出力された電気信号値Ｖ_ｉと砥石車とワ−ク間の距離Ｌ_ｉ、および該電気信号値Ｖ_ｉにおける砥石車とワ−ク間の距離の振れ幅ｌ_ｉとから砥石車とワ−ク間の距離が０以上となる電気信号値Ｖ_ｉと下降速度Ｓ_ｉの相関から砥石車の下降速度Ｓ_ｉをより速度が小さい下降速度Ｓ_ｉ＋ _１に切替える基準電気信号値Ｕ_ｉおよび下降速度を切り替える回数ｎを決め、この基準電気信号値Ｕ_ｉとこの基準電気信号値Ｕ_ｉを検出した際に切替える砥石車下降速度Ｓ_ｉ＋ _１および砥石車の下降を停止する基準電気信号値Ｕ_０および下降速度を切り替える回数ｎを予め記憶する記憶手段、ならびに、
前記非接触センサ手段から出力された電気信号値Ｖ_ｉを前記記憶手段に記憶された基準電気信号値Ｕ_ｉと比較し、非接触センサ手段から出力された電気信号値Ｖ_ｉが基準電気信号値Ｕ_ｉに一致したときに砥石車の下降速度Ｓ_ｉを下降速度Ｓ_ｉ＋ _１に切替えと、非接触センサ手段から出力された電気信号値Ｖ_ｉが基準電気信号値Ｕ_０に一致したときに砥石車の下降動作を停止させる制御手段、
とを備えることを特徴とする、研削装置を提供するものである。
【００２５】
砥石車の下降速度を自動的に高速から低速へと順次切り替えて、砥石車底部とワ−ク表面間の距離が約０．０２ｍｍとなる切り込み開始点位置へ砥石車を接近させるに要する時間が短縮される。また、砥石車の最終下降速度が小さいので、万が一、砥石車底部がワ−クに衝突したとしても、火花の発生は無いか、仮にあったとしても小さく、また、ワ−クが破損することはない。
【００２６】
本発明の請求項２は、前記研削装置において、非接触センサ手段が、レ−ザ光センサ、超音波センサおよび空気圧力センサより選ばれた電圧信号を出力するものであることを特徴とする。
【００２７】
これら非接触センサ手段は、砥石車底部とのワ−ク表面間距離を電圧信号に変えて研削装置の制御装置の記録部（ＲＡＭ）および記憶部（ＲＯＭ）に出力できる。
【００２８】
本発明の請求項３は、前記センサ手段を備えた研削装置を用い、予め砥石車を一定速度で回転させつつ、砥石車を下降速度Ｓ_ｉで下降させて表面に研削液が一定量で供給されているワ−クに接近させて非接触センサ手段より出力された電気信号値Ｖ_ｉと砥石車とワ−ク間の距離Ｌ_ｉ、および該電気信号値Ｖ_ｉにおける砥石車とワ−ク間の距離の振れ幅ｌ_ｉとから砥石車とワ−ク間の距離が０以上となる電気信号値Ｖ_ｉと下降速度Ｓ_ｉの相関から砥石車の下降速度Ｓ_ｉを下降速度Ｓ_ｉ＋ _１に切替える基準電気信号値Ｕ_ｉおよび下降速度を切り替える回数ｎを決め、この基準電気信号値Ｕ_ｉとこの基準電気信号値Ｕ_ｉを検出した際に切替える砥石車下降速度Ｓ_ｉ＋ _１および砥石車の下降を停止する基準電気信号値Ｕ_０および下降速度を切り替える回数ｎを記憶手段に入力して記憶させ、
加工するワ−クをテ−ブル上に載せた後、ワ−ク表面に前記一定量の研削液を供給しつつ、前記一定の回転速度で回転している砥石車を下降速度Ｓ_ｉで自動的に下降させてワ−クに接近させていき、その砥石下降時に前記非接触センサ手段から出力された電気信号値Ｖ_ｉを前記記憶手段に記憶された基準電気信号値Ｕ_ｉと比較し、非接触センサ手段から出力された電気信号値Ｖ_ｉが基準電気信号値Ｕ_ｉに一致すると自動的に砥石下降速度Ｓ_ｉを下降速度Ｓ_ｉ＋ _１に切替えてワ−クへの砥石車の接近を行ない、前記非接触センサ手段から出力された電気信号値Ｖ_ｉが基準電気信号値Ｕ_０に一致したときに砥石車の下降動作を自動的に停止させることを特徴とする、砥石車のワ−クへの接近方法を提供するものである。
【００２９】
高速から低速へと砥石車の下降速度を自動的に切り替えて砥石車底部をワ−ク表面近傍に砥石車を接近させることができるので、この砥石車を切り込み開始点（例えば砥石車の底部とワ−ク表面間距離を０．０２ｍｍと設定）位置へ接近させるに要する時間が短縮される。
【００３０】
【発明の実施の形態】
以下、図面を用いて本発明を更に詳細に説明する。
図１は、本発明の非接触センサ手段を備える研削装置の部分正面図、図２は制御装置の回路、図３は本発明方法のフロ−シ−ト図、図４は砥石車下降速度を種々変化させた際の砥石車・ワ−ク間距離（縦軸）と非接触センサ手段が出力したデジタル電気信号値の相関図である。図５は本発明の一実施例を示す砥石車の下降速度を変化させつつ測定した検出器が発信するデジタル電気信号値とワ−ク・砥石車間距離の相関を示す図である。
【００３１】
図１において、１は平面研削装置、２はワ−クで、水平方向（Ｘ軸方向）に往復移動可能なテ−ブル上に置かれたチャック４上に載せられている。９は砥石車、１０は操作盤、１２は研削液供給ノズル、１３は制御ユニット部（ＣＰＵ）、３００は前述の株式会社キ−エンスの長距離デジタルレ−ザセンサＬＶ−Ｈ３７（商品名）で、３０１は増幅器、３０２はレ−ザ光投光／受光器である。
【００３２】
図２に示す制御ユニット部１３において、この制御部（ＣＰＵ）は記憶部ＲＯＭと記録部ＲＡＭと比較器を備え、研削機械側Ｉ／Ｏポ−ト３１７よりサ−ボモ−タ、サ−ボバルブ、研削装置１本体のシ−ケンス３１８に繋がれている。
【００３３】
次に図４を用いて制御装置の記憶部ＲＯＭに記憶される砥石車の下降速度Ｓ_ｉと下降速度Ｓ_ｉ＋ _１に切替える基準電気信号値Ｕ_ｉを決める方法について述べる。　実際に研削するに用いる砥石車を研削装置１の砥石軸に装着し、研削加工時の砥石の周速度で砥石車を回転させる。図４は、直径３５０ｍｍ、砥石幅３８ｍｍの砥石ＷＡ６０Ｈ８Ｖを用い、周速度３０ｍ／分で砥石車を回転させながら図に示される下降速度で砥石車を下降させて研削液が表面に供給されているワ−クに接近させた場合の出力信号Ｖ_ｉ（ｄｅｊｉｔ）と砥石車の底部とワ−ク表面間の距離Ｌ_ｉの相関を実測し、その相関図を示したものである。
【００３４】
この実測の際、ワ−ク表面には実際の研削と同一条件の研削液５〜２５リットル／分をワ−ク表面に供給しつつ行う。ノズル３０より噴射された研削液はワ−ク２上に薄膜を形成し、ワ−クと砥石車間距離が約２ｍｍのところまでは明度に変化はないが、回転する砥石車９がワ−ク２に接近するにつれて薄膜内に細かい気泡を含み始め、さらに砥石車がワ−クに接近するにつれて細かい気泡を含んだ白色の帯状の研削液流を形成し、この気泡の量は砥石車がワ−クに接近するほど多くなる。即ち、明度は明るくなり、レ−ザ光の反射受光量は増加するのでトリガ値も増加する。
【００３５】
非接触センサ手段として用いられた長距離デジタルレ−ザセンサ３００は、回転している砥石車の下を通過したワ−ク２表面の研削液流に投光／受光器３０２からレ−ザ光（λ＝６５０ｎｍ）をワ−ク表面に照射（投光）し、反射した光を受光してレ−ザ散乱光強度を検出器３０１が電気信号値（４桁のｄｉｇｉｔ）で出力するもので、予め実験により電気信号のトリガ値とワ−ク・砥石車間の距離を求め、記憶装置に登録しておく。
【００３６】
ワ−ク表面上の研削液流へのレ−ザ光の投光角度は３０〜９０度が好ましい。図１では投光角度９０度である。投光角度が小さい程、より砥石車の底部直下に近い研削液流の反射レ−ザ光の受光量を検出でき、精度は高くなる。長距離デジタルレ−ザセンサ３００の投光／受光器３０２は砥石車のカバ−に設けてもよいし、テ−ブル４に取り付けてもよい。
【００３７】
制御ユニット部（ＣＰＵ）１３は、ＯＫデ−タ（Ｅ）記憶部のＲＯＭ、デ−タ書き換えのラッチ回路部のＲＡＭから構成される。
本発明の砥石車のワ−クへの接近方法において、図４の相関図を用い、一例として砥石切り込み開始点をワ−ク表面より約０．０２ｍｍの位置とする方法を次に記載する。砥石車の下降速度の自動切替えは２〜５回（ｉ＝３〜６）とする。
【００３８】
図４より電気信号値Ｖ_ｉと砥石車とワ−ク間の距離Ｌ_ｉ、および該電気信号値Ｖ_ｉにおける砥石車とワ−ク間の距離の振れ幅ｌ_ｉとから砥石車とワ−ク間の距離が０以上となる電気信号値Ｖ_ｉとそのときの砥石車下降速度Ｓ_ｉを基準値として３つ選択する。選択される砥石車下降速度Ｓ_ｉは、電気信号値Ｖ_ｉのときの砥石車とワ−ク間の距離Ｌ_ｉが重なる部分があるものを選択するのが好ましい。
【００３９】
砥石車下降速度の切り替え回数ｎが２回（ｉ＝３）のとき、砥石車下降速度Ｓ_ｉとして最初Ｓ_１は７５ｍｍ／分、砥石車下降速度Ｓ_ｉを切り替える基準電気信号値Ｕ_ｉとして１回目Ｕ_１は１６０ｍＶとし、この電圧信号１６０ｍＶがカラ−識別センサ３００から出力されたときに砥石車下降速度Ｓ_２を５０ｍｍ／分と設定し、２回目の基準電気信号値Ｕ_２は２００ｍＶとし、この電圧信号２００ｍＶがカラ−識別センサ３００から出力されたときに切り替える砥石車下降速度Ｓ_３を５ｍｍ／分と設定し、３回目（最終）の基準電気信号値Ｕ_０は３５０ｍＶと設定する。この電圧信号３５０ｍＶが長距離デジタルレ−ザセンサ３００から出力され、これを比較器で確認され、その出力を受けた制御ユニット部１３は砥石車の下降を停止する指令をサ−ボモ−タ１５に出力する（図３参照）。
【００４０】
砥石車下降速度の切り替え回数ｎが、図５に示す４回（ｉ＝５）のとき、砥石車下降速度Ｓ_ｉとして最初Ｓ_１は１００ｍｍ／分、第１回目の砥石車下降速度Ｓ_２７５ｍｍ／分に切り替える基準電気信号値Ｕ_ｉとして１回目Ｕ_１は１６０ｍＶとし、この電圧信号１６０ｍＶが長距離デジタルレ−ザセンサ３００から出力されたときに第２回目の砥石車下降速度Ｓ_３を５０ｍｍ／分に切り替えるその２回目の基準電気信号値Ｕ_２は２１０ｍＶとし、この電圧信号２１０ｍＶが長距離デジタルレ−ザセンサ３００から出力されたときに第３回目に切り替える砥石車下降速度Ｓ_４を２５ｍｍ／分と設定し、３回目の基準電気信号値Ｕ_３は２５０ｍＶとし、この電圧信号２５０ｍＶが長距離デジタルレ−ザセンサ３００から出力されたときに第４回目に切り替える砥石車下降速度Ｓ_５を５ｍｍ／分と設定し、４回目（最終）の基準電気信号値Ｕ_０は３４０ｍＶと設定する。この電圧信号３４０ｍＶが長距離デジタルレ−ザセンサ３００から出力され、これを比較器で確認され、その出力を受けた制御ユニット部１３は砥石車の下降を停止する指令をサ−ボモ−タ１５に出力する。
【００４１】
前記Ｖ_ｉの値は、砥石車径、砥石車の回転速度（周速度）、砥石車幅、研削液供給量に依存するので、図４の相関図は、実際の研削条件で行って作成する必要がある。
【００４２】
これら砥石車下降速度の切り替え回数ｎ、砥石車下降速度Ｓ_ｉ、基準電気信号値Ｕ_ｉ、最終基準電気信号値Ｕ_０を記憶部ＲＯＭに記憶させ、砥石車の切り込み開始点位置検出Ｏｎ−Ｏｆｆスィッチ１０ａをＯｎとし、下降速度Ｓ_１で砥石車を待機位置より自動的に下降させつつ、非接触センサ３００が読み取った研削液薄膜の明度のデジタル値（Ｖ_ｉ）をカウンタ−で読み取り、ラッチ回路（ＲＡＭ）に送信し、前述のＲＯＭに入力されたデ−タＵ_ｉと、順次ＲＡＭに送信されてくる電機信号のデジタル値Ｖ_ｉを比較し、デジタル値Ｖ_ｉが記憶したＵ_ｉの値に一致もしくは記憶したＵ_ｉのしきり範囲の数値に達する度に砥石車の下降速度Ｓ_ｉが次の下降速度Ｓ_ｉ＋ _１に切り替えられ、デジタル値Ｖ_ｉが最終電気信号値Ｕ_０に一致もしくは記憶したＵ_０のしきり範囲の数値に達したとき、切り替えの切り込み開始点としてシ−ケンサ３１８より研削装置１の制御ユニット部１３に伝達し、サ−ボモ−タ１４の駆動を停止させる指示を出力するとともに、操作盤１０上の砥石の切り込み開始点位置検出Ｏｎ−Ｏｆｆスィッチ１０ａに伝え、スィッチ１０ａの色を緑から赤に変化させて作業者に砥石車が切り込み開始点に到達したことを報せるとともに、スイッチ１０ａをＯｆｆに切り替える。
砥石車の下降停止時、砥石車９とワ−ク間の距離は、約０．０２ｍｍとなっているが、厳密に０．０２ｍｍに設定することを希望するなら作業者は手動で手パハンドルを回転させて送り速度０．００１ｍｍ／分で微調整する。
【００４３】
ついで、作業者は、切り込み速度（砥石車の加工速度）の設定を切り替え、砥石切り込み開始点位置検出Ｏｎ−Ｏｆｆスィッチ１０ａをＯｆｆのまま、手パハンドルを回転させてワ−クの切り込みを手動で開始するか、砥石ジョグボタン１０ｂを押してワ−クの切り込みを手動で開始する。
または、作業者は、切り込み速度（砥石車の下降速度）の設定を切り替え、砥石切り込み開始点位置検出Ｏｎ−Ｏｆｆスィッチ１０ａをＯｎに切り替え、スタ−トボタンを押してワ−クへの砥石車の自動切り込みを開始する。
【００４４】
図３に砥石車をワ−クに接近させる本発明のフロ−シ−トを示す。
先に実験を行って作製した図４より砥石車の下降速度切り替え回数ｎ（ｎ＝ｉ−１）、砥石車の下降速度Ｓ_ｉ、基準電気信号値Ｕ_ｉ、この基準電気信号値Ｕ_ｉとこの基準電気信号値Ｕ_ｉを検出した際に切替える砥石車下降速度Ｓ_ｉ＋ _１および砥石車の下降を停止する基準電気信号値Ｕ_０を決め、これらデ−タを制御ユニット部１３の記憶部に入力する。
【００４５】
加工するワ−ク２をテ−ブル３上のチャック４上に載せた後、ワ−ク表面に前記一定量の研削液を供給しつつ、砥石切り込み開始点設定のスタ−トボタンを押す。
【００４６】
一定の回転速度で回転している砥石車を砥石待機位置より設定された下降速度Ｓ_ｉで自動的に下降させてワ−クに接近させていき、その砥石下降時に前記非接触センサ手段から出力された電気信号値Ｖ_ｉを前記記憶手段に記憶された基準電気信号値Ｕ_ｉと比較する。
【００４７】
非接触センサ手段から出力された電気信号値Ｖ_ｉが基準電気信号値Ｕ_ｉに一致すると自動的に砥石下降速度Ｓ_ｉを下降速度Ｓ_ｉ＋ _１に切替えてワ−クへの砥石車の接近を行なう。
【００４８】
前記非接触センサ手段から出力された電気信号値Ｖ_ｉが基準電気信号値Ｕ_０に一致したときに砥石車の下降動作を自動的に停止させる。
【００４９】
実施例１
直径３５０ｍｍ、幅３８ｍｍのポ−ラスタイプのＣ／ＧＣ８０Ｉ１４Ｖ砥石車を砥石軸に備えた株式会社　岡本工作機械製作所のＣＮＣ平面研削装置　ＰＳＧ−６３ＥＸ（商品名）の左右移動テ−ブルに、株式会社キ−エンスの長距離デジタルレ−ザセンザＬＶ−３７Ｈ（商品名）を備え、テ−ブル上のチャックに取り付けたワ−クＦＣ２００に１０リットル／分の研削液（Ｗ２−１の５０倍希釈液）を供給しつつ、テ−ブルを停止させた状態で、図５に示す砥石車下降速度の切り替え回数ｎが４回（ｉ＝５）、砥石車下降速度Ｓ_ｉとして最初Ｓ_１は１００ｍｍ／分、第１回目の砥石車下降速度Ｓ_２７５ｍｍ／分に切り替える基準電気信号値Ｕ_ｉとして１回目Ｕ_１は１６０ｍＶとし、この電圧信号１６０ｍＶが長距離デジタルレ−ザセンサ３００から出力されたときに第２回目の砥石車下降速度Ｓ_３を５０ｍｍ／分に切り替えるその２回目の基準電気信号値Ｕ_２は２１０ｍＶとし、この電圧信号２１０ｍＶが長距離デジタルレ−ザセンサ３００から出力されたときに第３回目に切り替える砥石車下降速度Ｓ_４を２５ｍｍ／分と設定し、３回目の基準電気信号値Ｕ_３は２５０ｍＶとし、この電圧信号２５０ｍＶが長距離デジタルレ−ザセンサから出力されたときに第４回目に切り替える砥石車下降速度Ｓ_５を５ｍｍ／分と設定し、４回目（最終）の基準電気信号値Ｕ_０は３４０ｍＶと設定し、砥石車を３２ｍ／秒で回転させながら砥石車の底部がワ−ク表面から５ｍｍ離れている位置から砥石車をワ−ク表面に向けて自動的に接近させた。
なお、長距離デジタルレ−ザセンザのレ−ザ光のワ−ク表面への投光角度は３０度、ワ−クと投光器間の距離は８０ｍｍである。
【００５０】
電圧信号３４０ｍＶが長距離デジタルセンサから出力され、砥石車の下降が停止されるまでに要した時間は、３．７秒であった。砥石車の下降が停止された際の砥石車・ワ−ク表面間の距離は０．０２ｍｍであった。
【００５１】
比較例１
株式会社　岡本工作機械製作所のＣＮＣ平面研削装置　ＰＳＧ−６３ＥＸ（商品名）の左右移動テ−ブル上チャックに取り付けたワ−クＦＣ２００に、テ−ブルが停止している状態で手動で作業者がワ−ク表面より５ｍｍ離れた位置より３２ｍ／秒で回転している砥石車をワ−クに１５秒以内で接近させるか５人に試行させたところ、砥石車・ワ−ク表面間の距離は平均０．３５ｍｍであった。
【００５２】
以上、非接触センサ手段として、長距離デジタルレ−ザセンサ手段を例に挙げて本発明の砥石車のワ−クへの自動接近方法を述べたが、非接触センサ手段は砥石車とワ−ク間の距離Ｌｉを検出し、電気信号で出力する非接触センサ手段であれば如何なるセンサでもよく、公知技術または先願発明技術の欄で既述した水中マイクロホン、空気圧力センサ、カラ−識別センサなども利用できる。
【００５３】
【発明の効果】
本発明は、非接触で砥石切り込み開始点を砥石車の下降速度を切り替えて自動的に設定できるので、砥石切り込み開始点位置調整を短時間で行うことができ、また、砥石車衝突によりワ−クが破損する機会が減少した。
【図面の簡単な説明】
【図１】平面研削装置の一部を切り欠いた正面図である。
【図２】制御部の平面図である。
【図３】本発明の砥石車を切り込み開始点近傍に位置決めするフロ−シ−トである。
【図４】砥石車の下降速度を種々変えた際の砥石車・ワ−ク間距離と非接触センサ手段より出力された電気信号（電圧）の相関図である。
【図５】砥石車の下降速度を変化させつつ測定した検出器のトリガ値とワ−ク・砥石車間距離の相関を示す図である。
【図６】カラ−識別センサを非接触センサ手段として備える研削装置の部分正面図である。（公知）
【図７】水中マイクロホンを非接触センサ手段として備える研削装置の部分正面図である。
【図８】平面研削装置の斜視図である。（公知）
【図９】平面研削装置の側面図である。（公知）
【図１０】平面研削装置のブロック図である。（公知）
【図１１】一定速度で砥石車をワ−クに接近させたときの砥石車・ワ−ク間距離（ΔＹ）とレ−ザ散乱光強度の電機信号値（Ｖ_ｉ）との相関図である。
【符号の説明】
１　　　　平面研削装置
２　　　　ワ−ク
３　　　　テ−ブル
４　　　　チャック
９　　　　砥石車
１２　　　研削液供給ノズル
１３　　　制御ユニット部
３００　　非接触センサ
３０１　　検出器
３０２　　投光／受光器[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and a method for automatically bringing a grinding wheel close to a work surface when determining a starting point of cutting of the grinding wheel with respect to the work without contacting the bottom of the grinding wheel with the work. It relates to a grinding device to be implemented.
[0002]
[Prior art]
There is known an NC grinding apparatus which performs plunge grinding, traverse grinding, plane processing forming, grooving, and machining of a workpiece such as a metal, ceramic, or silicon substrate (Japanese Patent Application Laid-Open No. 55-83567, JP-A-59-59349, JP-A-61-173851, JP-A-4-13552, JP-A-2000-135675, JP-A-2000-271866, JP-A-2000-317829, JP-A-2001-170832, Patent No. 2694189, Patent No. 3023018), Okamoto Machine Tool Works, Hitachi Seiko, Nagase Integrex, Sigia (Taiwan), Kellenberger (Switzerland), Jones & & Shipman PLC (UK), Jung (Germany), Taccella Machine < p. A (Italy) and the like.
[0003]
8, 9 and 10 show an example of the surface grinding machine 1. FIG. In the drawing, 2 is a work, 3 is a table that can reciprocate in the left-right direction (X-axis direction), 4 is an electromagnetic chuck, 5 is a saddle that can reciprocate in the front-rear direction (Z-axis direction), and 6 is a saddle. A grinding wheel device, 7 is a column provided with an elevating mechanism for moving the grinding wheel in the vertical direction (Y-axis direction), 8 is a grinding wheel shaft head, 9 is a grinding wheel provided on the grinding wheel shaft, and M is a grinding wheel shaft rotation drive motor. Reference numeral 10 denotes an operation panel, 11 denotes a bed, 12 denotes a grinding fluid supply nozzle, 13 denotes a control unit, 14 denotes a shaft device, and 15 denotes a servomotor.
[0004]
The power for raising and lowering the grinding wheel shaft head 8 in the vertical direction (Y-axis direction) is transmitted from the servo motor 15 to the grinding wheel shaft head 8 via a gear 16, a feed screw 17, and a screw receiver 18.
It is assumed that the relative position function between the table 3 and the work 2 is known (for example, a scale of HEIDENHAIN is mounted on the table, and the left end of the work is connected to a limit switch mounted on the table). The touched position is defined as the work reference origin, and the left end reversal position of the table is defined as the table origin.
[0005]
19 is a function generator, 20 is a grinding amount setting device, 21 is a pulse generation circuit, and 22 is a drive circuit.
In the function generator 19, a function formula corresponding to a work shape to be ground is set in advance by a grinding amount setting device 20 (for example, an operation key of the interactive numerical control operation panel 10). This function formula uses the position detection signal A as a variable. Therefore, the function generator 19 calculates the grinding amount signal B corresponding to the input position detection signal A and continuously outputs the same.
The grinding amount signal B is provided to the next pulse generation circuit 21. The pulse generation circuit 21 performs signal processing on the grinding amount signal B, converts it into a control pulse signal C, and outputs the control pulse signal C to the drive circuit 22.
The drive circuit 22 rotates the servomotor 15 in accordance with the amount to be ground at the current table position, so that the grindstone 9 is set at an appropriate height position.
The above operation is performed via the control unit 13 in response to an operation command from the operation panel 10.
[0006]
In this surface grinding apparatus 1, the work 2 is fixed to the chuck 4 on the table 3, the saddle 5 is moved to determine the position in the Z-axis direction, and the table 3 is reciprocated in the X-axis direction. In the process, the rotating grinding wheel 9 provided on the grinding wheel shaft head 8 is brought into contact with the work 2, and the grinding wheel shaft head is fed in the Y-axis direction by the servo motor 15 and the ball screw 17. Cut and grind the work. At this time, the grinding fluid is supplied from the grinding fluid supply nozzle 12 to the work surface.
[0007]
Although not shown, a servo valve hydraulic cylinder driving method (Japanese Patent No. 3023018), a method in which a ball screw is driven by a servo motor, or a table is used to feed the table 3 left and right. Is directly driven by a linear motor.
[0008]
BACKGROUND ART A grinding device for grinding a disc-shaped grinding wheel rotated by an electric motor to a desired cutting amount from above a work (workpiece) is provided by a worker who is required to perform (1) a grinding wheel and a work. While watching the distance of the gap between the wheels, rotate the handle connected to the manual pulse generator or press the jog button to move the grinding wheel close to the work. While rotating the handle 10a while watching the distance of the gap between the workpieces, the grinding wheel is approached to the work at a speed lower than the descending speed of the grinding wheel in the above process, and (3) the position where a slight spark has flew or This is performed by recognizing the position of the changed state of the grinding fluid as the cutting start point.
[0009]
The adjusting operation of the cutting start point position is performed not only by a manual grinding device but also by an NC grinding device. In the case of the NC grinding apparatus, once this operation is performed to determine the starting position of the cutting edge of the grindstone with respect to the work, the work of the work can be automatically performed in accordance with the machining software program. When repeatedly producing parts with the same dimensions, pre-estimate the variation in the pre-processing dimensions, lower the grinding wheel at a high speed to a safe position that is a certain distance away from the processing point, and position it. The air-cut time is prolonged because the grinding wheel is gradually approached to the work to start the actual grinding.
The work of bringing the high-speed rotating grinding wheel close to the work is not easy even for a skilled technician, and must be performed based on the intuition and experience of the worker. The skill of a skilled technician is required because the outer diameter of the grindstone changes every moment due to wear and dressing of the grindstone, and it takes a long time to master this skill.
[0010]
In addition, this operation requires a long time when the grinding wheel is gently approached to the work and the fine cutting is started from a point where the distance between the grinding wheel and the work is far from the starting point. Conversely, if the grinding wheel is brought close to the work at a high speed, the grinding wheel will violently collide with the work and damage the grinding wheel or give damage to the work that cannot be removed by grinding. Therefore, the work of determining the starting point of the grinding wheel cutting is the work that the worker dislikes most.
[0011]
Various proposals have been made to automate the determination of the grinding wheel cutting start point using a non-contact sensor. For example, Japanese Utility Model Laid-Open Publication No. Sho 63-110371 discloses a distance sensor for measuring the distance between the upper surface of a work mounted on a table and the machined surface of a rotating grinding wheel in a non-contact manner. Japanese Unexamined Patent Publication No. 6-55414 discloses a method of determining the position between a work and a grindstone using an ultrasonic sensor, and Japanese Unexamined Patent Publication No. 2000-326224 discloses an air pressure sensor. A method of using an AE sensor to approach a grinding wheel to a starting position for cutting into a work will be described.
[0012]
Further, Japanese Patent Application Laid-Open No. 2000-263436 discloses a color identification sensor 300 comprising a laser light projecting / receiving end portion and an amplifier having a display for displaying the amount of received light, as shown in FIG. -23 A grinding liquid is supplied from a nozzle 12 to the surface of a work 2 placed on a magnetic chuck 4 mounted on a horizontally movable table mounted on a side surface of the work table, and ground on the work surface. A liquid thin film is formed, and the surface of the thin film is irradiated with light from the light source of the color identification sensor 300, and the reflected light is condensed on an optical fiber to recognize the color component of the light. E_iIs transmitted to the arithmetic unit of the control unit 13, and the rotating grinding wheel 9 provided in the direction perpendicular to the work surface is lowered to the work surface. As the rotating grinding wheel 9 approaches the work, The air is entrained in the liquid thin film formed on the work surface to generate fine bubbles inside the liquid thin film, and the value E of the color component of light is obtained._iProvides a method in which the position of the grindstone with respect to the work when the color component Eo of the light of the grinding fluid thin film in which bubbles are generated in the memory of the CPU is set as the starting point of cutting of the grindstone.
[0013]
Japanese Patent Application No. 2001-176408 discloses a method in which a grinding fluid is supplied from a nozzle 12 installed near a grindstone 9 of a grinding device to a wafer mounted on a magnetic chuck 4 on a table as shown in FIG. A nozzle for supplying the grinding fluid while lowering the grinding wheel 9 rotating with respect to the workpiece surface while supplying the grinding fluid to the workpiece surface while feeding the workpiece to the workpiece point of the workpiece 2; The sound pressure signal of the grinding fluid received by the underwater microphone 300 installed in the filter 12 is passed through a band-pass filter 307 that passes a predetermined frequency band, and a fundamental frequency is extracted from the sound pressure signal that has passed through the band-pass filter. , The value of the sound pressure signal at the fundamental frequency (P_i) Is the value of the sound pressure signal (P₀) Is reached (P_i= P₀A method is proposed for determining the time as the starting point for cutting the grinding wheel with respect to the work.
[0014]
A color identification sensor utilizing laser light, a distance digital laser sensor instead of the color identification sensor, or a sensor means 300 for generating an electric signal such as an underwater microphone using ultrasonic waves, an air pressure sensor, etc., is provided. The grinding device 1 has the advantage that the distance between the grinding wheel and the work can be measured in a non-contact manner and the position of the starting point of cutting into the work of the grinding wheel can be automatically set. Since the distance between the wheel and the work is output by an electric signal, when the descending speed of the grinding wheel 9 rotating at a constant speed is as large as 100 mm / min, the thickness of the grinding liquid thin film on the work and the air flow Is not constant, the amplitude of the output digital electric signal (dejit) changes.
[0015]
FIG. 11 shows a long-distance digital laser sensor as a non-contact sensor for measuring the distance from a received light amount of reflected laser light projected on a work surface to a work. Using an LV-H37 (trade name), while the table is stopped, the grinding wheel rotating at 32 m / sec is approached while supplying 10 l / min of grinding oil to the work surface. FIG. 5 is a correlation diagram between the work-to-grinding wheel distance and the digital electric signal trigger value (laser scattered light intensity) in the case of FIG. The output waveform contains a considerable amount of noise.
[0016]
FIG. 4 shows the distance between the trigger value of the digital electric signal indicated by the digital laser sensor LV-H37 and the work wheel when measured using the long distance digital laser sensor LV-H37 (trade name). It is shown.
[0017]
In the case where the trigger level is constant and the descending speed of the grinding wheel 9 rotating at a constant speed is as large as 100 mm / min, the output (degitated) electric signal V_iOf the positioning accuracy is 0.3 to 0.04 mm, and when the descent speed is 10 mm / min, the variation is about 0.02 mm. Also, when the descending speed is high, the moving amount of the grinding wheel due to the time delay after the output of the stop signal becomes large, and there is a possibility that an overshoot may occur.
[0018]
When the descending speed of the grinding wheel 9 is as large as 100 mm / min, it is necessary to stop the wheel at a distance close to 0.5 mm in order to avoid collision of the grinding wheel with the work. Yes, the mode is switched to manual, the lowering speed of the grinding wheel 9 is switched to a lower speed, and the remaining distance is lowered while manually turning the handwheel. If the lowering speed of the grinding wheel is reduced to 5 mm / min, the lower portion of the grinding wheel 9 can be automatically brought close to the cutting start point distance near 0.02 mm of the work surface. There is a drawback that the time required for approaching is longer.
[0019]
The inventor of the present invention varied the descending speed of the grinding wheel 9 rotating at a constant speed in various ways to approach an output signal V when approaching the work._i(MV) and the distance L between the bottom of the grinding wheel and the work surface_iWere actually measured, and the correlation diagram is shown in FIG. In FIG. 4, a curve or a broken line indicates the output signal V_iL between the bottom of the grinding wheel and the work surface at_iThe vertical line indicates the output signal V_iOf the distance between the work surfaces at L_iIs shown.
[0020]
FIG. 4 shows that when the descending speed of the grinding wheel 9 is set at 100 mm / min, the distance between the bottom of the grinding wheel and the surface of the work is 0.267 mm to -0.0 mm even when the output signal value is 170 mV. 122 mm, which indicates that there is a deviation of 0.389 mm between the values.
When the grinding wheel 9 is lowered at this descending speed and the grinding wheel actually contacts the work (for example, the distance between the grinding wheel and the work is -0.122 mm), a large spark scatters and the operation of a beginner is performed. Will be surprised. That is, actual interference between the grinding wheel and the work occurs, and the object of the present invention is not achieved.
[0021]
As the lowering speed of the grinding wheel 9 to be set becomes smaller, the runout width becomes smaller sequentially. When the setting of the descending speed of the grinding wheel 9 is 75 mm / min, the distance between the bottom of the grinding wheel and the work surface is any one of -0.05 mm to +0.11 mm even if the output signal value is 190 mV. There is a deviation of 0.16 mm between these values. When the setting of the descending speed of the grinding wheel 9 is 50 mm / min, the distance between the bottom of the grinding wheel and the work surface is any one of 0.025 mm to 0.145 mm even if the output signal value is 210 mV. The deviation between the values is 0.120 mm. When the setting of the descending speed of the grinding wheel 9 is 25 mm / min, the distance between the bottom of the grinding wheel and the work surface is any one of 0.005 mm to 0.065 mm even if the output signal value is 260 mV. The deviation between the values is 0.060 mm.
[0022]
Further, when the setting of the descending speed of the grinding wheel 9 is 5 mm / min, the distance between the bottom of the grinding wheel and the work surface is any one of 0.015 mm to 0.035 mm even if the output signal value is 340 mV. The deviation between the values is 0.020 mm, and the grinding wheel does not come into contact with the work. When the setting of the descending speed of the grinding wheel 9 is 5 mm / min and the output signal value is 350 mV, the distance between the bottom of the grinding wheel and the work surface is any one of -0.005 mm to +0.025 mm. There is a deviation of 0.020 mm between these values. When the grinding wheel 9 is lowered at the lowering speed of 5 mm / min and the output signal value becomes 350 mV and the lowering of the grinding wheel is stopped, the lowering speed is low even if the grinding wheel actually contacts the work. No or no sparks are generated, and the work is not damaged.
[0023]
[Problems to be solved by the invention]
The present invention uses a sensor capable of detecting the distance between the grinding surface of a grinding wheel and the surface to be ground of the work in a non-contact manner, and quickly determines the starting point of cutting of the grinding wheel by moving the grinding wheel near the work in a short time. It is an object of the present invention to provide a method for approaching a workpiece and a grinding device capable of implementing a method for approaching a work of a grinding wheel using the non-contact sensor.
[0024]
[Means for Solving the Problems]
Claim 1 of the present invention is a horizontally movable table on which a work is placed;
A disk-shaped grinding wheel provided so as to be vertically movable with respect to the surface of the table, lifting means and rotation driving means for the grinding wheel,
A nozzle for supplying a grinding liquid to a surface of a work placed on the table;
Distance L between the grinding wheel and the work_iNon-contact sensor means for detecting and outputting an electric signal,
While rotating the grinding wheel at a constant speed in advance, the grinding wheel_iAnd the electric signal value V output from the non-contact sensor means measured by approaching the work._iAnd distance L between grinding wheel and work_i, And the electric signal value V_iOf the distance between the grinding wheel and the work at l_iAnd the electric signal value V at which the distance between the grinding wheel and the work becomes 0 or more_iAnd descent speed S_iOf the grinding wheel from the correlation of_iTo the lowering speed S_{i +} ₁To switch to the reference electric signal value U_iAnd the number n of switching of the descending speed are determined, and the reference electric signal value U_iAnd this reference electric signal value U_iWheel switching speed S to be switched to when wheel speed is detected_{i +} ₁And the reference electric signal value U for stopping the lowering of the grinding wheel₀Storage means for storing in advance and the number n of switching the descending speed, and
The electric signal value V output from the non-contact sensor means_iIs the reference electric signal value U stored in the storage means._iAnd the electric signal value V output from the non-contact sensor means._iIs the reference electric signal value U_iWhen the grinding wheel descent speed S_iIs the descending speed S_{i +} ₁And the electric signal value V output from the non-contact sensor means_iIs the reference electric signal value U₀Control means for stopping the descending operation of the grinding wheel when
And a grinding device provided with the following.
[0025]
The time required to bring the grinding wheel closer to the cutting start point where the distance between the grinding wheel bottom and the work surface is about 0.02 mm by automatically switching the descending speed of the grinding wheel from high speed to low speed automatically. Be shortened. In addition, since the final descending speed of the grinding wheel is small, no spark is generated even if the bottom of the grinding wheel collides with the work, or even if it is small, the work may be damaged. There is no.
[0026]
According to a second aspect of the present invention, in the grinding apparatus, the non-contact sensor means outputs a voltage signal selected from a laser light sensor, an ultrasonic sensor, and an air pressure sensor.
[0027]
These non-contact sensor means can convert the distance between the work surface and the bottom of the grinding wheel into a voltage signal and output the voltage signal to a recording unit (RAM) and a storage unit (ROM) of the control device of the grinding machine.
[0028]
Claim 3 of the present invention uses a grinding device provided with the sensor means, and rotates the grinding wheel at a lower speed S while rotating the grinding wheel at a constant speed in advance._iTo approach a work in which a predetermined amount of grinding fluid is supplied to the surface, and the electric signal value V output from the non-contact sensor means._iAnd distance L between grinding wheel and work_i, And the electric signal value V_iOf the distance between the grinding wheel and the work at l_iAnd the electric signal value V at which the distance between the grinding wheel and the work becomes 0 or more_iAnd descent speed S_iOf the grinding wheel from the correlation of_iIs the descending speed S_{i +} ₁To switch to the reference electric signal value U_iAnd the number n of switching of the descending speed are determined, and the reference electric signal value U_iAnd this reference electric signal value U_iWheel switching speed S to be switched to when wheel speed is detected_{i +} ₁And the reference electric signal value U for stopping the lowering of the grinding wheel₀And the number of times n at which the descent speed is switched is input and stored in the storage means,
After the work to be processed is placed on the table, the grinding wheel rotating at the constant rotation speed is lowered while the constant amount of the grinding fluid is supplied to the surface of the work._iTo automatically approach the work, and the electric signal value V output from the non-contact sensor means when the grindstone is lowered._iIs the reference electric signal value U stored in the storage means._iAnd the electric signal value V output from the non-contact sensor means._iIs the reference electric signal value U_iAutomatically matches the wheel descent speed S_iIs the descending speed S_{i +} ₁And the wheel is approached to the work, and the electric signal value V output from the non-contact sensor means._iIs the reference electric signal value U₀And a method of approaching the grinding wheel to the work, characterized in that the lowering operation of the grinding wheel is automatically stopped when the following conditions are satisfied.
[0029]
Since the lowering speed of the grinding wheel can be automatically switched from high speed to low speed to bring the grinding wheel bottom closer to the surface of the work, the grinding wheel can be cut into a starting point (for example, the bottom of the grinding wheel and the bottom of the grinding wheel). (The distance between the work surfaces is set to 0.02 mm).
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings.
FIG. 1 is a partial front view of a grinding device having a non-contact sensor means of the present invention, FIG. 2 is a circuit diagram of a control device, FIG. 3 is a flowchart of the method of the present invention, and FIG. It is a correlation diagram of the distance between a grinding wheel and a work (vertical axis) and the digital electric signal value output by the non-contact sensor means when variously changed. FIG. 5 is a view showing the correlation between the digital electric signal value transmitted from the detector and the distance between the work and the grinding wheel measured while changing the descending speed of the grinding wheel according to one embodiment of the present invention.
[0031]
In FIG. 1, reference numeral 1 denotes a surface grinding device, and 2 denotes a work, which is mounted on a chuck 4 placed on a table capable of reciprocating in a horizontal direction (X-axis direction). 9 is a grinding wheel, 10 is an operation panel, 12 is a grinding fluid supply nozzle, 13 is a control unit (CPU), and 300 is the long distance digital laser sensor LV-H37 (trade name) of KEYENCE CORPORATION. Reference numeral 301 denotes an amplifier, and 302 denotes a laser light projecting / receiving device.
[0032]
In the control unit section 13 shown in FIG. 2, the control section (CPU) includes a storage section ROM, a storage section RAM, and a comparator, and a servo motor and a servo valve are provided from a grinding machine side I / O port 317. Are connected to a sequence 318 of the main body of the grinding device 1.
[0033]
Next, the descending speed S of the grinding wheel stored in the storage unit ROM of the control device using FIG._iAnd descent speed S_{i +} ₁To switch to the reference electric signal value U_iThe method of determining is described. (4) The grinding wheel used for actual grinding is mounted on the grinding wheel shaft of the grinding device 1, and the grinding wheel is rotated at the peripheral speed of the grinding wheel during the grinding process. FIG. 4 shows that a grinding wheel WA60H8V having a diameter of 350 mm and a grinding wheel width of 38 mm is used, while the grinding wheel is rotated at a peripheral speed of 30 m / min. Output signal V when approaching the work_i(Dejit) and the distance L between the bottom of the grinding wheel and the work surface_iAre actually measured, and the correlation diagram is shown.
[0034]
At the time of this actual measurement, the grinding is performed while supplying a grinding liquid of 5 to 25 liters / minute under the same conditions as the actual grinding to the work surface. The grinding fluid sprayed from the nozzle 30 forms a thin film on the work 2, and there is no change in brightness up to a distance of about 2 mm between the work and the grinding wheel, but the rotating grinding wheel 9 is As the wheel approaches the work piece, it begins to contain fine bubbles in the thin film, and as the wheel approaches the work, it forms a white band-like grinding fluid stream containing the fine bubbles, and the amount of the bubbles is determined by the grinding wheel. -The more you get closer to the target, the more it gets. That is, since the brightness becomes bright and the amount of reflected light received by the laser beam increases, the trigger value also increases.
[0035]
The long-distance digital laser sensor 300 used as a non-contact sensor means emits laser light (light from the light emitting / receiving device 302) to the grinding fluid flow on the surface of the work 2 passing under the rotating grinding wheel. λ = 650 nm) is irradiated (projected) onto the work surface, the reflected light is received, and the laser scattered light intensity is output by the detector 301 as an electric signal value (four digits). The trigger value of the electric signal and the distance between the work and the grinding wheel are obtained in advance by experiments and registered in the storage device.
[0036]
The projection angle of the laser beam to the grinding fluid flow on the work surface is preferably 30 to 90 degrees. In FIG. 1, the light projection angle is 90 degrees. As the light projection angle is smaller, the amount of reflected laser light received from the grinding fluid flow closer to immediately below the bottom of the grinding wheel can be detected, and the accuracy becomes higher. The light emitting / receiving device 302 of the long distance digital laser sensor 300 may be provided on the cover of the grinding wheel or may be attached to the table 4.
[0037]
The control unit (CPU) 13 comprises a ROM of an OK data (E) storage unit and a RAM of a latch circuit for rewriting data.
In the method of approaching the grinding wheel to the work according to the present invention, a method for setting the starting point of the cutting of the grinding wheel at about 0.02 mm from the surface of the work will be described as an example using the correlation diagram of FIG. The automatic switching of the descending speed of the grinding wheel is performed 2 to 5 times (i = 3 to 6).
[0038]
From FIG. 4, the electric signal value V_iAnd distance L between grinding wheel and work_i, And the electric signal value V_iOf the distance between the grinding wheel and the work at l_iAnd the electric signal value V at which the distance between the grinding wheel and the work becomes 0 or more_iAnd the grinding wheel descending speed S at that time_iAre selected as reference values. Grinding wheel descending speed S to be selected_iIs the electric signal value V_iThe distance L between the grinding wheel and the work_iIt is preferable to select one having a portion where.
[0039]
When the number n of switching of the grinding wheel descent speed is two (i = 3), the grinding wheel descent speed S_iAs the first S₁Is 75 mm / min, grinding wheel descending speed S_iTo switch the reference electric signal value U_iFirst time as U₁Is 160 mV. When the voltage signal 160 mV is output from the color identification sensor 300, the grinding wheel descent speed S₂Is set to 50 mm / min, and the second reference electric signal value U₂Is 200 mV, and the wheel wheel descent speed S to be switched when the voltage signal 200 mV is output from the color identification sensor 300.₃Is set to 5 mm / min, and the third (final) reference electric signal value U₀Is set to 350 mV. The voltage signal of 350 mV is output from the long-distance digital laser sensor 300, which is confirmed by a comparator. Upon receiving the output, the control unit 13 sends a command to the servo motor 15 to stop the lowering of the grinding wheel. Output (see FIG. 3).
[0040]
When the number n of switching of the grinding wheel lowering speed is four (i = 5) shown in FIG._iAs the first S₁Is 100 mm / min, the first grinding wheel descent speed S₂Reference electric signal value U to switch to 75 mm / min_iFirst time as U₁Is 160 mV. When the voltage signal 160 mV is output from the long distance digital laser sensor 300, the second grinding wheel descent speed S₃Is switched to 50 mm / min., The second reference electric signal value U₂Is set to 210 mV. When the voltage signal 210 mV is output from the long distance digital laser sensor 300, the grinding wheel descent speed S to be switched for the third time is set.₄Is set to 25 mm / min, and the third reference electric signal value U₃Is 250 mV. When the voltage signal 250 mV is output from the long distance digital laser sensor 300, the grinding wheel descent speed S to be switched for the fourth time is₅Is set to 5 mm / min, and the fourth (final) reference electric signal value U₀Is set to 340 mV. The voltage signal 340 mV is output from the long-distance digital laser sensor 300, which is confirmed by a comparator. Upon receiving the output, the control unit 13 sends a command to the servo motor 15 to stop the lowering of the grinding wheel. Output.
[0041]
V_iDepends on the grinding wheel diameter, the rotation speed (peripheral speed) of the grinding wheel, the width of the grinding wheel, and the supply amount of the grinding fluid. Therefore, the correlation diagram in FIG. 4 needs to be created by performing under actual grinding conditions. .
[0042]
The number of switching of the grinding wheel descent speed n, the grinding wheel descent speed S_i, The reference electric signal value U_i, The final reference electric signal value U₀Is stored in the storage unit ROM, the cutting start point position detection On-Off switch 10a of the grinding wheel is set to On, and the descending speed S₁While the grinding wheel is automatically lowered from the standby position, the non-contact sensor 300 reads the digital value (V_i) Is read by a counter, transmitted to a latch circuit (RAM), and the data U_iAnd the digital value V of the electric signal sequentially transmitted to the RAM_iIs compared with the digital value V_iU remembered_iU that matches or memorizes the value of_iEach time the value reaches the threshold range, the grinding wheel descent speed S_iIs the next descent speed S_{i +} ₁Is switched to the digital value V_iIs the final electric signal value U₀U that matches or is stored in₀When the value reaches the threshold range, the sequencer 318 transmits the switching cut start point to the control unit 13 of the grinding apparatus 1 and outputs an instruction to stop the driving of the servo motor 14. While detecting the cutting start point position of the grinding wheel on the operation panel 10 to the On-Off switch 10a, changing the color of the switch 10a from green to red and notifying the worker that the grinding wheel has reached the cutting start point, The switch 10a is turned off.
When the grinding wheel stops descending, the distance between the grinding wheel 9 and the work is about 0.02 mm. However, if it is desired to set strictly 0.02 mm, the operator manually operates the handwheel. Rotate for fine adjustment at a feed rate of 0.001 mm / min.
[0043]
Next, the operator switches the setting of the cutting speed (the processing speed of the grinding wheel), and turns the hand grip handle manually while turning off the grinding wheel cutting start point position detection On-Off switch 10a to manually cut the work. To start or press the grinding wheel jog button 10b to manually start the cutting of the work.
Alternatively, the operator switches the setting of the cutting speed (the descending speed of the grinding wheel), switches the grinding wheel cutting start point position detection On-Off switch 10a to On, and presses the start button to automatically move the grinding wheel to the work. Start incision.
[0044]
FIG. 3 shows a flow sheet of the present invention for bringing a grinding wheel close to a work.
From FIG. 4 produced by conducting the above-mentioned experiment, the number of times of switching of the descending speed of the grinding wheel n (n = i-1), the descending speed S of the grinding wheel_i, The reference electric signal value U_i, This reference electric signal value U_iAnd this reference electric signal value U_iWheel switching speed S to be switched to when wheel speed is detected_{i +} ₁And the reference electric signal value U for stopping the lowering of the grinding wheel₀Is determined, and these data are input to the storage unit of the control unit 13.
[0045]
After the work 2 to be processed is placed on the chuck 4 on the table 3, the start button for setting the starting point for cutting the grinding wheel is pressed while supplying the above-mentioned fixed amount of the grinding liquid to the surface of the work.
[0046]
The descending speed S set from the grinding wheel standby position to the grinding wheel rotating at a constant rotational speed._iTo automatically approach the work, and the electric signal value V output from the non-contact sensor means when the grindstone is lowered._iIs the reference electric signal value U stored in the storage means._iCompare with
[0047]
Electric signal value V output from the non-contact sensor means_iIs the reference electric signal value U_iAutomatically matches the wheel descent speed S_iIs the descending speed S_{i +} ₁Then, approach the grinding wheel to the work.
[0048]
The electric signal value V output from the non-contact sensor means_iIs the reference electric signal value U₀Automatically stops the lowering operation of the grinding wheel when it is equal to.
[0049]
Example 1
Includes a porous C / GC80I14V grinding wheel with a diameter of 350 mm and a width of 38 mm on the grinding wheel shaft. CNC surface grinding machine of Okamoto Machine Tool Works, Ltd. PSG-63EX (trade name) Equipped with a long distance digital laser sensor LV-37H (trade name) of Enss, a grinding fluid of 10 liters / minute (50-fold diluted solution of W2-1) in a work FC200 attached to a chuck on a table. While the table is stopped, the number of times n of the grinding wheel descent shown in FIG. 5 is changed four times (i = 5), and the grinding wheel descent speed S is increased._iAs the first S₁Is 100 mm / min, the first grinding wheel descent speed S₂Reference electric signal value U to switch to 75 mm / min_iFirst time as U₁Is 160 mV. When the voltage signal 160 mV is output from the long distance digital laser sensor 300, the second grinding wheel descent speed S₃Is switched to 50 mm / min., The second reference electric signal value U₂Is set to 210 mV. When the voltage signal 210 mV is output from the long distance digital laser sensor 300, the grinding wheel descent speed S to be switched for the third time is set.₄Is set to 25 mm / min, and the third reference electric signal value U₃Is 250 mV, and when the voltage signal 250 mV is output from the long distance digital laser sensor, the wheel wheel descent speed S to be switched for the fourth time is₅Is set to 5 mm / min, and the fourth (final) reference electric signal value U₀Was set to 340 mV, and while the grinding wheel was rotated at 32 m / sec, the grinding wheel was automatically moved toward the work surface from a position where the bottom of the grinding wheel was 5 mm away from the work surface.
The angle of projection of the laser beam from the long distance digital laser sensor onto the work surface is 30 degrees, and the distance between the work and the projector is 80 mm.
[0050]
The time required for the voltage signal 340 mV to be output from the long distance digital sensor and for the descent of the grinding wheel to be stopped was 3.7 seconds. When the descent of the grinding wheel was stopped, the distance between the grinding wheel and the work surface was 0.02 mm.
[0051]
Comparative Example 1
Okamoto Machine Tool Works Co., Ltd. CNC surface grinding machine @Worker manually attached to the work FC200 attached to the upper chuck of the left / right moving table of PSG-63EX (trade name) while the table is stopped. When a grind wheel rotating at a speed of 32 m / sec from a position 5 mm away from the work surface is approached to the work within 15 seconds or five people try it, the distance between the grind wheel and the work surface is determined. Was 0.35 mm on average.
[0052]
As described above, the method of automatically approaching a grinding wheel to a work according to the present invention has been described by taking a long-distance digital laser sensor as an example of the non-contact sensor. Any sensor may be used as long as it detects the distance Li between the sensors and outputs the electric signal as a non-contact sensor. Also available.
[0053]
【The invention's effect】
According to the present invention, the grinding wheel cutting start point can be automatically set by switching the descent speed of the grinding wheel in a non-contact manner, so that the grinding wheel cutting start point position can be adjusted in a short time, and the grinding wheel collides with the grinding wheel. The chance of damage to the metal has been reduced.
[Brief description of the drawings]
FIG. 1 is a front view in which a part of a surface grinding device is cut away.
FIG. 2 is a plan view of a control unit.
FIG. 3 is a flow sheet for positioning the grinding wheel of the present invention in the vicinity of a cutting start point.
FIG. 4 is a correlation diagram of the distance between the grinding wheel and the work and the electric signal (voltage) output from the non-contact sensor means when the descending speed of the grinding wheel is variously changed.
FIG. 5 is a diagram showing a correlation between a trigger value of a detector and a distance between a work and a grinding wheel measured while changing a descending speed of the grinding wheel.
FIG. 6 is a partial front view of a grinding device provided with a color identification sensor as a non-contact sensor means. (Known)
FIG. 7 is a partial front view of a grinding device provided with an underwater microphone as a non-contact sensor means.
FIG. 8 is a perspective view of a surface grinding device. (Known)
FIG. 9 is a side view of the surface grinding device. (Known)
FIG. 10 is a block diagram of a surface grinding device. (Known)
FIG. 11 shows an electric signal value (V) of the distance (ΔY) between the grinding wheel and the work and the laser scattered light intensity when the grinding wheel is brought close to the work at a constant speed._iFIG.
[Explanation of symbols]
1 Surface grinding machine
2 work
3 table
4 chuck
9 grinding wheel
12 grinding fluid supply nozzle
13 control unit
300mm non-contact sensor
301 detector
302 Emitter / Receiver

Claims

A horizontally movable table on which to place the work,
A disk-shaped grinding wheel provided so as to be vertically movable with respect to the surface of the table, lifting means and rotation driving means for the grinding wheel,
A nozzle for supplying a grinding liquid to a surface of a work placed on the table;
Non-contact sensor means for detecting the distance L _i between click, outputs an electric signal, - the grinding wheel and the follower
While the pre-grinding wheel is rotated at a constant speed, lowers the grinding wheel at a lowering speed S _i Wa - electric signal value output from the non-contact sensor unit as measured by proximity to click V _i and the grinding wheel and the follower - the grinding wheel at a distance between click L _i, and the electrical signal values V _i and word - the grinding wheel and a deflection width l _i of the distance between click and word - the distance between the click becomes 0 or more electrical signal value V _From the correlation between _i and the descending speed S _i, the reference electric signal value U _i for switching the descending speed S _i of the grinding wheel to the lower descending speed S _{i +} ₁ and the number n of times for switching the descending speed are determined. _i and the reference electrical signal values U ₀ and pre-stored to the storage unit the number of times n for switching the descending speed stops the lowering of the grinding wheel lowering speed S _{i +} ₁ and the grinding wheel is switched upon detection of the reference electrical signal value U _i, And
The non-contact electrical signal values V _i output from the sensor means as compared to the stored reference electrical signal value U _i in the storage means, the non-contact sensor means output from the electric signal value V _i is the reference electric signal value and switches the wheel lowering speed S _i in lowering speed S _{i +} ₁ when they match a U _i, the grinding wheel when the electric signal value V _i output from the non-contact sensor means coincides with the reference electrical signal value U ₀ Control means for stopping the lowering operation of
And a grinding device.

The grinding apparatus according to claim 1, wherein the non-contact sensor means outputs a voltage signal selected from a laser light sensor, an ultrasonic sensor, and an air pressure sensor.

Using a grinding apparatus according to claim 1, in advance while the grinding wheel is rotated at a constant speed, Wa grinding fluid is supplied at a constant amount to the surface by lowering the grinding wheel at a lowering speed S _i - approaching click is brought to the non-contact sensor electrical signal value outputted from the means V _i and the grinding wheel and the word - the distance between click L _i, and the grinding wheel in the electric signal values V _i and word - amplitude of distance between click l _i grinding wheel and word from the - reference electrical signal value switches the lowering speed S _i of the grinding wheel lowering speed S _{i +} ₁ from the correlation of the electrical signals the distance between the click is 0 or more values V _i and the descending speed S _i U _i and determining the number of times n to switch the lowering speed, the reference electrical signal value for stopping the lowering of the reference electrical signal value U _i grinding wheel lowering speed S _{i +} ₁ and the grinding wheel is switched upon detection of the reference electrical signal value U _i storing hand the number of times n for switching the U ₀ and lowering speed Entered and stored in the,
Processing for word - Te a click - after placing on table, Wa - while supplying the predetermined amount of the grinding liquid on the click surface, automatically with lowering speed S _i the grinding wheel rotating at the constant rotational speed and to lowered word - it continues to close to the click, as compared to the reference electrical signal value U _i of the electrical signal value V _i output from the non-contact sensor unit when the grinding wheel descends stored in said storage means, non-contact sensor means automatically switches the grindstone lowering speed S _i in lowering speed S _{i +} ₁ when the electric signal value V _i output matches the reference electrical signal value U _i from word - the approach of the grinding wheel to click deeds, the non-contact sensor means an electric signal value V _i output from which is characterized in that to automatically stop the downward movement of the grinding wheel when it coincides with the reference electrical signal value U _0, of the grinding wheel word - How to approach