JP3634146B2

JP3634146B2 - Grinding wheel shaping error correction method, grinding wheel shaping / straight groove forming grinding error correction method, and error correction devices thereof

Info

Publication number: JP3634146B2
Application number: JP12789998A
Authority: JP
Inventors: 孝原田
Original assignee: 三菱マテリアル神戸ツールズ株式会社
Priority date: 1998-05-11
Filing date: 1998-05-11
Publication date: 2005-03-30
Anticipated expiration: 2018-05-11
Also published as: JPH11320402A

Description

【０００１】
【発明の属する技術分野】
本発明は、加工装置上で砥石形状や成形研削されたワークの加工形状を測定し、その測定結果から砥石やワークを目標通りに加工するための補正加工ＮＣデータを自動的に作成し、砥石やワークを加工装置から取り外すことなく砥石整形やインボリュート平歯車等の直溝を成形研削加工する砥石整形誤差補正方法及び砥石整形・直溝成形研削加工誤差補正方法並びにそれらの誤差補正装置に関するものである。
【０００２】
【従来の技術】
歯車の研削仕上げには、研削砥石と歯面とを噛み合い運動させることによって研削を行う創成法と、加工する形状に合同な形状の砥石を用いて１歯ずつ割り出しながら研削を行う成形法とがあるが、成形法は研削効率が良く、任意の歯形をもつ歯車の研削ができる点で小量多品種生産に適している。ただし、この成形法は、創成法に比べ、製品の加工精度に左右する要素、例えば研削砥石における整形誤差、研削砥石と工作物の相対的な位置関係における誤差が含まれているため、これらの誤差をいかに補正するかが歯車の研削仕上げ精度を高める上での課題となっている。
【０００３】
また、ＮＣ研削加工機上に砥石整形機を備えているＮＣ成形研削加工機は、砥石の整形から研削加工までを同時に行うことができるため、ワークの加工形状に対応して砥石を交換する手間がなく、また、砥石交換に伴う取り付け誤差も発生しないため、短時間で高精度の加工を行なうことができると期待されている。しかし、現実には、砥石整形機の据え付け位置誤差や摩耗等による形状誤差によって砥石が目標通りの形状に加工されていないため、研削加工されたワークの形状に誤差が生じていた。また、目標通りに整形された砥石を用いたとしても、加工するワークに対して砥石の据え付け位置が正確に与えられていないと、ワークを目標通りの形状に加工することができない。
【０００４】
そこで、本発明の発明者は、加工するワークに対する砥石の位置誤差をＮＣ研削加工機上で補正する方法を、先に特開平９−１１０８５号公報（先行技術）に示した。その補正方法に従えば、先端が球形の接触子をＮＣ研削加工機の工具保持台に取り付け、非研削部分（ワーク外周面）と加工部分（歯形面）をそれぞれ計測し、既知であるワーク形状及び加工形状と計測データとの距離が上記接触子球の半径になるように、ＮＣ研削加工機座標におけるワーク形状座標と加工形状座標の相対的な位置関係を求め、これと目標の位置関係との差を加工工具の位置決め誤差とし、その誤差を補正するようなＮＣ加工データをＮＣ研削加工機に与えることにより、目標通りの加工を実現することができるようになっている。
【０００５】
【発明が解決しようとする課題】
しかしながら、上記補正方法は、砥石が目標通りの形状に整形されていることを前提として歯車の仕上げ精度を向上させるものであるため、砥石の形状に誤差が含まれていることまでは考慮されていない。
【０００６】
本発明は以上のような従来の課題を考慮してなされたものであり、砥石形状に誤差が含まれている場合に、その誤差を補正しつつ砥石形状を緒元通りに加工することができ、また、砥石形状を緒元通りに加工するとともにワークを緒元通りに加工してワークの仕上げ精度を向上させることができる砥石整形誤差補正方法及び砥石整形・直溝成形研削加工誤差補正方法並びにそれらの誤差補正装置を提供するものである。
【０００７】
【課題を解決するための手段】
本発明の砥石整形誤差補正方法は、先端部の寸法が既知である測定子を、ＮＣ砥石整形機で整形された整形面に接触させた時のＮＣ駆動軸座標を計測し、該計測によって得られた計測点についての座標データを記憶し、前記ＮＣ砥石整形機の据え付け位置誤差及び形状誤差に対する砥石断面形状曲線誤差の幾何学的関係をモデル化し、加工する砥石諸元及び前記据え付け位置誤差及び形状誤差を含むモデルから与えられる砥石断面形状曲線に任意の砥石断面形状曲線座標系を与え、この砥石断面形状曲線座標系内の任意の点と前記砥石断面形状曲線との距離を表す式を求め、この式に基づいて求められる、前記砥石に前記測定子を接触させたときの前記計測点と前記砥石断面形状曲線との距離が、前記接触子先端部における既知寸法と等しくなるように、前記ＮＣ駆動軸座標と前記砥石断面形状曲線座標の相対的位置関係と、前記モデル化により与えられた砥石断面形状曲線誤差を計算し、前記砥石断面形状曲線誤差から、前記砥石整形機の据え付け位置誤差及び形状誤差を計算し、これらの誤差を補正する値を砥石整形ＮＣデータとして用い、砥石形状を諸元通りに加工することを要旨とする。
【０００８】
本発明の砥石整形・直溝成形研削加工誤差補正方法は、先端部の寸法が既知である測定子を、砥石整形機で整形された砥石を用いて成形研削加工されたワークの、非研削部分と成形研削部分である研削溝とにそれぞれ接触させた時のＮＣ駆動軸座標を計測し、該計測によって得られた計測点についての座標データを記憶し、前記砥石整形機の据え付け位置誤差及び形状誤差に対する砥石断面形状曲線誤差の幾何学的関係をモデル化し、ワーク諸元から与えられる前記非研削部分についてのワーク形状曲線に任意のワーク形状曲線座標系を与え、このワーク形状曲線座標系内の任意の点と前記ワーク形状曲線との距離を表す第１の式を求め、加工する砥石諸元及び前記据え付け位置誤差及び形状誤差を含むモデルから与えられる砥石断面形状曲線と合同である研削溝断面形状曲線に任意の研削溝断面形状曲線座標系を与え、この研削溝断面形状曲線座標系内の任意の点と前記研削溝断面形状曲線との距離を表す第２の式を求め、前記第１の式に基づいて求められる、前記ワークの非研削部分に前記測定子を接触させたときの前記計測点と前記ワーク形状曲線との距離が、前記接触子先端部における既知寸法と等しくなるように、前記ワーク形状曲線座標と前記ＮＣ駆動軸座標の相対的位置関係を計算し、前記第２の式に基づいて求められる、前記研削溝に前記測定子を接触させたときの前記計測点と前記研削溝断面形状曲線との距離が、前記接触子先端部における既知寸法と等しくなるように、前記研削溝断面形状曲線座標と前記ＮＣ駆動軸座標の相対的位置関係と、前記モデル化により与えられた砥石断面形状曲線誤差と等しい研削溝断面形状曲線誤差を計算し、前記研削溝断面形状誤差から、前記砥石整形機の据え付け位置誤差ならび形状誤差を計算し、これらの誤差を補正する値を砥石整形ＮＣデータとして用い、前記ワーク形状曲線座標と前記ＮＣ駆動軸座標の相対的位置関係、及び前記研削溝断面形状曲線座標と前記ＮＣ駆動軸座標の相対的位置関係から、前記ワーク形状曲線座標と前記研削溝断面形状曲線座標の相対位置関係を計算し、目標とする相対位置との誤差を補正する成形研削加工用ＮＣデータを与え、それにより砥石形状を諸元通りに整形するとともに、前記ワークを諸元通りに研削加工することを要旨とする。
【０００９】
本発明の砥石整形誤差補正装置は、先端部の寸法が既知である測定子を、ＮＣ砥石整形機で整形された整形面に接触させた時のＮＣ駆動軸座標を計測する計測手段と、該計測によって得られた計測点についての座標データを記憶する記憶手段と、前記ＮＣ砥石整形機の据え付け位置誤差及び形状誤差に対する砥石断面形状曲線誤差の幾何学的関係をモデル化し、加工する砥石諸元及び前記据付け位置誤差及び形状誤差を含むモデルから与えられる砥石断面形状曲線に任意の砥石断面形状曲線座標系を与え、この砥石断面形状曲線座標系内の任意の点と前記砥石断面形状曲線との距離を計算する計算手段と、この計算手段により求められる、前記砥石に前記測定子を接触させたときの前記計測点と砥石断面形状曲線との距離が、前記接触子先端部における既知寸法と等しくなるように、前記ＮＣ駆動軸座標と前記砥石断面形状曲線座標の相対的位置関係と、前記モデル化により与えられた砥石断面形状曲線誤差を計算する手段と、前記砥石断面形状曲線誤差から、前記砥石整形機の据え付け位置誤差及び形状誤差を計算し、これらの誤差を補正する値を砥石整形ＮＣデータとして用い、砥石形状を諸元通りに加工する補正手段と、を備えてなることを要旨とする。
【００１０】
本発明の砥石整形・直溝成形研削加工誤差補正装置は、先端部の寸法が既知である測定子を、ＮＣ砥石整形機で整形された砥石を用いて成形研削加工されたワークの、非研削部分と成形研削部分である研削溝とにそれぞれ接触させた時のＮＣ駆動軸座標を計測する計測手段と、該計測によって得られた計測点についての座標データを記憶する記憶手段と、前記砥石整形機の据え付け位置誤差及び形状誤差に対する砥石断面形状曲線誤差の幾何学的関係をモデル化し、ワーク諸元から与えられるワーク形状曲線に任意のワーク形状曲線座標系を与え、このワーク形状曲線座標系内の任意の点と前記ワーク形状曲線との距離を計算するとともに、加工する砥石諸元及び前記誤差を含むモデルから与えられる砥石断面形状曲線と合同である研削溝断面形状曲線に任意の研削溝断面形状曲線座標系を与え、この研削溝断面形状曲線座標系内の任意の点と前記研削溝断面形状曲線との距離を計算する計算手段と、この計算手段により求められる、前記ワークの非研削部分に前記測定子を接触させたときの前記計測点と前記ワーク形状曲線との距離が、前記接触子先端部における既知寸法と等しくなるように、前記ワーク形状曲線座標と前記ＮＣ駆動軸座標の相対的位置関係を計算する手段と、前記計算手段により求められる、前記研削溝に前記測定子を接触させたときの前記計測点と前記研削溝断面形状曲線との距離が前記接触子先端部における既知寸法と等しくなるように、前記研削溝断面形状曲線座標とＮＣ駆動軸座標の相対的位置関係と、前記モデル化により与えられた砥石断面形状曲線誤差と等しい研削溝断面形状曲線誤差を計算する手段と、前記研削溝断面形状誤差から、前記砥石整形機の据え付け位置誤差ならび形状誤差を計算し、これらの誤差を補正する値を砥石整形ＮＣデータとして用い、前記ワーク形状曲線座標と前記ＮＣ駆動軸座標の相対的位置関係、及び前記研削溝断面形状曲線座標と前記ＮＣ駆動軸座標の相対的位置関係から、前記ワーク形状曲線座標と前記研削溝断面形状曲線座標の相対位置関係を計算し、目標とする相対位置との誤差を補正する成形研削加工用ＮＣデータを与え、それにより砥石形状を諸元通りに整形するとともに、前記ワークを諸元通りに研削加工する補正手段と、を備えてなることを要旨とする。
【００１１】
本発明の誤差補正方法及び誤差補正装置において、測定子はＮＣ砥石整形機のベースまたは砥石保持部に設けることが好ましい。
【００１２】
本発明において、非研削部分及び成形研削部分とは、ワークが例えば歯車の研削に使用されるものである場合には、ワークの外周（歯先円に相当する）及び歯形をそれぞれ意味する。なお、上記歯車の例では、歯車の歯先円の中心＝歯車の中心という仮定を設け、ワークの外周部分を計測することによりワークの中心を求めているが、本発明の非研削部分には、ワークの中心を求めることができるワーク上の任意の形状が含まれる。従って上記外周部分に限らず、例えば中心に対して正確に穴が穿設されているようなワークでは、その穴の内周部分を計測することによってもワークの中心を求めることができる。
【００１３】
【発明の実施の形態】
以下、図面に示した実施の形態に基づいて本発明を詳細に説明する。
なお、本発明は、砥石やワークの形状に限定されないが、以下の実施形態では、直溝成形研削加工の典型例としてインボリュート平歯車の成形研削加工を例に取って説明する。また、説明に際しては（１）第一の形態として砥石整形誤差補正方法及びそれに用いる誤差補正装置について説明した後、（２）第二の形態として砥石整形・成形研削加工誤差補正方法及びそれに用いる誤差補正装置について説明する。
【００１４】
まず、第一及び第二の形態に用いられる多石回転型砥石整形機付き５軸ＮＣ歯車研削加工装置（以下、単にＮＣ研削加工装置と呼ぶ）の構成を、図１を参照しながら説明する。
【００１５】
同図において、ｘ軸テーブル１は左右方向（ｘ軸方向）に往復移動するようになっており、割出台２のワーク保持部２ａはワーク３を保持した状態でＡ軸まわりに回転するようになっている。
【００１６】
ｙ軸テーブル４は、前後方向（ｙ軸方向）に前進または後退するようになっており、このｙ軸テーブル４上には、上下方向（ｚ軸方向）に昇降可能なｚ軸テーブル５が備えられている。このｚ軸テーブル５の前面には砥石保持部５ａが備えられ、この砥石車保持部５ａの先端に被削歯車の歯溝の形状に整形された砥石６が軸支されている。
【００１７】
また、７はＮＣ研削加工装置の基台に取り付けられた多石回転型砥石整形機（以下、ロータリドレッサと呼ぶ）である。
【００１８】
ＮＣコントローラ１０の記憶手段１０ａには、後述する測定子によって計測された座標データが格納される。上記測定子及びＮＣコントローラ１０は計測手段とみなすことができる。
【００１９】
距離計算手段１０ｂは、ロータリドレッサ７の据え付け位置誤差及び形状誤差に対する砥石断面形状曲線誤差（本実施形態では砥石歯形曲線誤差として説明する）の幾何学的関係をモデル化する。また、加工する砥石諸元及び誤差を含むモデルから与えられる砥石歯形曲線に任意の砥石歯形曲線座標系を与え、この砥石歯形曲線座標系内の任意の点と前記砥石歯形曲線との距離を計算する。
【００２０】
砥石歯形曲線誤差計算手段１０ｃは、前記距離検出手段１０ｂにより求められる、砥石６に測定子を接触させたときの計測点と砥石歯形曲線との距離が接触子先端部における既知寸法と等しくなるように、ＮＣ駆動軸座標と砥石歯形曲線座標の相対的位置関係と、モデル化により与えられた砥石歯形曲線誤差を計算する。
【００２１】
補正手段１０ｄは、上記砥石歯形曲線誤差から、ロータリドレッサ７の据え付け位置誤差及び形状誤差を計算し、これらの誤差を補正する値を砥石整形ＮＣデータとして用い、砥石形状を諸元通りに加工するようになっている。
【００２２】
このような構成のロータリドレッサ付きＮＣ研削加工装置による平歯車歯形の成形研削加工においては、まず、図２に示すように、ＮＣ駆動軸を動作させて、回転するロータリドレッサ７に砥石６を押し当てることにより、砥石６の整形を行う。図３は砥石６をロータリドレッサ７の一方側から他方側に移動させて砥石の右側及び左側をそれぞれ整形している様子を示しており、７ａは整形用石である。
【００２３】
なお、図１では、後述する砥石整形ならびに成形研削補正に関する実施形態を説明するために、歯形の成形研削も行える装置の構成を示しているが、第一の形態では砥石整形誤差補正のみを扱うため、歯形研削機能のない例えばＮＣ砥石研削盤であってもよい。
【００２４】
図４は、砥石整形時における砥石６に対するロータリドレッサ７の動作軌跡を示したものである。ロータリードレッサ７のエッジにはダイヤモンドなどで作られた整形用石７ａが固着されており、ロータリドレッサ７の動作は、そのエッジを動作参照点ｅとして与えられる。そして、この動作参照点ｅを砥石曲線ｆで動作させることにより、砥石６が整形される。
【００２５】
詳しくは、砥石曲線ｆの軌跡に対して、整形用石７ａの半径ｒｄを工具径補正値としてＮＣコントローラ１０に与えてやることにより、動作参照点ｅは砥石曲線ｆから整形用石半径ｒｄ分だけ離れた位置を移動することになり、その結果、砥石６が目標の砥石曲線ｆ通りに整形されることになる。
【００２６】
次に、上記第一の形態の砥石整形補正方法を、（ａ）〜（ｅ）の各ステップに分けて説明する。
【００２７】
（ａ）ロータリドレッサの据え付け位置誤差及び形状誤差に対する砥石歯形曲線誤差の幾何学的関係をモデル化する。
【００２８】
ロータリドレッサ７では、経年変化等によって整形用石７ａの半径ｒｄが変化して初期にＮＣコントローラ１０に設定した値とずれてきたり（形状誤差）、また、ロータリドレッサ７の回転軸芯がＮＣ加工機の垂直軸とずれている（据え付け位置誤差）場合があり、このような場合には砥石６を目標通りに整形することができない。
【００２９】
そこでまず、整形用石半径ｒｄの誤差が、砥石歯形形状に及ぼす影響を考える。インボリュート歯車歯形は、図５に示すインボリュート曲線の一部分を歯形曲線に使用しているが、実際の歯車では、図６に示すように、歯厚に応じてインボリュートのオフセット角度θ_０（インボリュート曲線の起点角度）を指定している。この場合、整形用石半径ｒｄの誤差は、図７に示すようにインボリュートのオフセット角度θ_０誤差を生じさせる。
【００３０】
同図（ａ）は整形用石半径ｒｄに誤差がない場合を示し、同図（ｂ）は整形用石半径ｒｄに誤差が生じた場合を示している。すなち、整形用石半径とインボリュートのオフセット角度とにおいて、正規の値と実際の値との誤差をそれぞれΔｒｄ、Δθ０としたとき、
【００３１】
【数１】

【００３２】
で与えられる。ただし、ｒｇはインボリュートの基礎円半経である。
【００３３】
次に、ロータリドレッサ７の回転軸芯誤差が、砥石歯形形状に及ぼす影響を考える。
【００３４】
通常、回転軸芯誤差は微小であると考えられるが、回転軸芯に誤差が生じると、図８に示すようにロータリドレッサ７の右側エッジ及び左側エッジの間で高さに差が生じる。この状態で砥石整形を行うと、図９に示すように、インボリュートのオフセット角度は等しいものの、基礎円中心の高さが左右で異なった状態になっていることがわかる。すなわち、インボリュート基礎円中心の高さ方向の差をΔｈｇ、ロータリドレッサ７の左右のエッジの高さの差をΔｈｄとしたとき、
【００３５】
【数２】

【００３６】
で与えられる。
【００３７】
以上のようにして、ロータリドレッサ７の据え付け位置誤差及び形状誤差に対する砥石歯形曲線誤差の幾何学的関係がモデル化される。
【００３８】
（ｂ）ＮＣ付きロータリドレッサ７のベースに、先端が球形からなる測定子８を取り付け、ＮＣ付きロータリドレッサ７で整形された砥石６にその測定子８を接触させた時のＮＣ駆動軸の値を計測し、計測結果をＮＣコントローラ１０の記憶手段１０ａに記憶する。
【００３９】
図１０に示す配置で、ＮＣ付きロータリドレッサ７を動作させ、図１１に示すように砥石６における整形部分に測定子８を接触させる。詳しくは、本実施形態では、ＮＣ研削加工装置のＹ，Ｚ軸を動作させて、砥石６の整形部分を測定子８に接触させ、接触させた時のＮＣ駆動軸の値を計測している。すなわち、図１２に示すように、砥石６の左右をそれぞれＮ_Ｌｉ、Ｎ_Ｒｉ点計測し、これを、
【００４０】
【数３】

【００４１】
として記憶しておく。これらの計測データの値は、ＮＣ駆動軸座標系における、測定子８の中心位置とみなすことができる。なお、本実施形態における測定子８は、先端部の変位や接触を電圧信号に変換して出力する機能を備えているものであれば、タッチセンサや電気マイクロセンサ等の任意のセンサを使用することができる。
【００４２】
( ｃ) 加工する砥石諸元および前記据え付け誤差及び形状誤差を含むモデルから与えられる砥石歯形曲線に任意の砥石歯形曲線座標系を与えて、この砥石歯形曲線座標系内の任意の点と前記砥石歯形曲線との距離を計算する。
【００４３】
上述したことから、ロータリドレッサ７の据え付け誤差及び砥石６の形状誤差が含まれる場合であってもインボリュート曲線の形状は変化せずに、インボリュートのオフセット角度と、左右の基礎円中心の高さのみ変化することがわかる。そこで、誤差を含んでいる砥石形状に対して、図１３に示すように、インボリュートのオフセット角度が“０” の位置に砥石歯形曲線の座標系を設定する。
【００４４】
砥石整形誤差があったとしても、砥石歯形曲線座標系における砥石歯形曲線は不変であり、横軸をＹ，縦軸をＺとする基準座標（ＮＣ駆動軸座標系における）に対して、座標の原点の位置と座標軸の方向が変化する。
【００４５】
次に、図１４を参照しながら、砥石歯形曲線座標系における点（ｐ，ｑ）と砥石歯形曲線（インボリュート曲線）との距離を計算する。同図に示す幾何学的関係より、
【００４６】
【数４】

【００４７】
となる。このθを用いて、点（ｐ，ｑ）と砥石歯形曲線（インボリュート曲線）との距離ｄは、
【００４８】
【数５】

【００４９】
という計算式で与えられる。
【００５０】
( ｄ) 前記計算式により求められる、砥石６に測定子８を接触させたときの計測点と砥石歯形曲線との距離が、接触子球の半径になるように、ＮＣ駆動軸座標と上記砥石歯形曲線座標の相対的位置関係と上記ステップ( ａ) のモデル化で与えられた砥石歯形曲線誤差を計算する。
【００５１】
図１４に示したように砥石歯形曲線座標をとることにより、この座標系には砥石歯形曲線誤差は反映されず（砥石歯形曲線は不変）、従ってＮＣ駆動軸座標と砥石歯形曲線座標の相対的位置関係にのみ考慮すればよい。
【００５２】
具体的には、図１３に示した左側の砥石歯形曲線座標の原点位置（Ｙ_ＧＬＯ，Ｚ_ＧＬＯ）、左右の基礎円中心の高さ誤差Δｈ_ｇ、オフセット角度誤差Δθ_０を座標変換パラメータとし、計測点と砥石歯形曲線がフィットする、すなわち、計測点と砥石歯形曲線との距離が接触子球の半径ｒｄになるように、座標変換パラメータを求めれば、ＮＣ駆動軸座標と砥石歯形曲線座標の相対的位置関係が導かれる。なお、計測点と砥石歯形曲線をフィットさせる手法としては、特開平９−１１０８５号公報で示した非線形の最小自乗法等を用いることができる。
【００５３】
このようにして、左側の砥石歯形曲線座標の原点位置（Ｙ_ＧＬＯ，Ｚ_ＧＬＯ）と、形状誤差である左右の基礎円中心の高さ誤差Δｈ_ｇとオフセット角度誤差Δθ_０が導かれる。
【００５４】
（ｅ）形状誤差から、ロータリドレッサ７の据え付け位置誤差ならび形状誤差を計算し、この誤差を補正するような砥石整形ＮＣデータをＮＣコントローラ１０に与える。
【００５５】
上述した式（１），（２）より、ロータリドレッサ７の据え付け位置誤差及び形状誤差に対する形状誤差の関係が与えられるので、逆に、
【００５６】
【数６】

【００５７】
により形状誤差から、ロータリドレッサ７の据え付け位置誤差ならび形状誤差を計算することができる。
【００５８】
ロータリドレッサ７の整形用石径ｒｄが初期にＮＣコントローラ１０に与えた値とずれてきたり（形状誤差）、また、ロータリドレッサ７の回転軸芯がＮＣ研削加工装置の垂直軸とずれている（据え付け位置誤差）などすると、図１５に示すように砥石６は目標通りに成形されないが、上述した方法で、ロータリドレッサ７の据え付け位置誤差と形状誤差を補正することにより、具体的には、据え付け位置誤差補正について、砥石６の左側を整形するときに、左右の高さ誤差分だけ整形するＮＣ軌跡をずらす。また、形状誤差補正について、整形用石誤差を現在の工具径補正値から引くことにより、目標通りの砥石６が整形されることになる（図１５（ｂ）参照）。
次に、第二の形態に係る砥石整形・成形研削補正方法について説明する。
【００５９】
図１に示したロータリドレッサ７付き５軸ＮＣ研削加工装置を用いて、砥石整形を行った後、平歯車歯形の成形研削加工を行う場合について説明する。
【００６０】
平歯車歯形の成形研削加工では、図１６（ａ）に示すようにワーク９の中心に対して砥石６を正確に位置決めする（ワーク中心とインボリュート基礎円中心を一致させる）ことによってはじめて目標の歯形を得ることが出来る。しかし、実際の加工ではＮＣ駆動軸の位置決め誤差があるために、図１６（ｂ）のようにワーク９中心とインボリュート基礎円中心が一致せず研削誤差が生じる。
【００６１】
先行技術である特開平９− １１０８５号公報では、図１７に示すようにＮＣ研削加工装置におけるＺ軸テーブル５に、先端が球形からなる測定子８を取り付け、測定子８を非研削部分９ａ（ワークの外周部分）と成形研削部分９ｂ（歯形部分）とに接触させた時のＮＣ駆動軸の値を用いて、砥石６の位置決め誤差を補正していた。しかしながら、この補正方法では、砥石６の整形誤差を考慮していないため、砥石６に整形誤差が含まれていると、ワーク９と砥石６との位置決め誤差の補正に誤差が生じることになる。
【００６２】
先に第一の形態で説明した方法で砥石整形を正確に行った後、特開平９− １１０８５号公報に記載の補正を行えば、より正確な歯形研削加工を実現することができるが、この場合、砥石形状測定用とワーク歯形形状測定用の２つの測定子が必要になり、冗長なシステムになってしまう。そこで、本発明では、成形研削されたワークの形状を測定することにより、砥石６の整形誤差及びワーク９に対する砥石６の位置決め誤差を一度に補正することができるようにしている。
【００６３】
図１７は第二の形態に使用する補正装置の構成を示したものである。なお、図１と同じ構成要素については同一符号を付してその説明を省略する。
【００６４】
同図において、ＮＣコントローラ２０の記憶手段２０ａは、ロータリドレッサ７で整形された砥石６を用いて成形研削加工されたワーク９の、ワーク外周部分（非研削部分）９ａと歯車歯形部分（研削溝）９ｂに測定子８を接触させることにより得られた座標データを記憶する。
【００６５】
距離計算手段２０ｂは、ロータリドレッサ７の据え付け位置誤差及び形状誤差に対する砥石歯形曲線誤差の幾何学的関係をモデル化し、ワーク諸元から与えられる前記ワーク外周部分９ａについてのワーク形状曲線に任意のワーク形状曲線座標系を与え、このワーク形状曲線座標系内の任意の点と前記ワーク形状曲線との距離を計算する。また、加工する砥石諸元及び前記据え付け誤差及び形状誤差を含むモデルから与えられる砥石歯形曲線と合同である歯車歯形曲線に任意の歯車歯形曲線座標系を与え、この歯車歯形曲線座標系内の任意の点と前記歯車歯形曲線との距離を計算する。
【００６６】
また、前記ワーク外周部分９ｂに測定子８を接触させたときの計測点とワーク形状曲線との距離が接触子球の半径となるように、ワーク形状曲線座標とＮＣ駆動軸座標の相対的位置関係を計算する。
【００６７】
歯車歯形曲線誤差計算手段２０ｃは、歯車歯形面に測定子８を接触させたときの計測点と歯車歯形曲線との距離が接触子球の半径となるように、歯車歯形曲線座標とＮＣ駆動軸座標の相対的位置関係と、モデル化方法で与えられた砥石歯形曲線誤差と等しい歯車歯形曲線誤差を計算する。
【００６８】
補正手段２０ｄは、上記歯車歯形形状誤差から、ロータリドレッサ７の据え付け位置誤差ならび形状誤差を計算し、これらの誤差を補正する値を砥石整形ＮＣデータとして用い、ワーク形状曲線座標とＮＣ駆動軸座標の相対的位置関係、及び歯車歯形曲線座標とＮＣ駆動軸座標の相対的位置関係から、ワーク形状曲線座標と歯車歯形曲線座標の相対位置関係を計算し、目標とする相対位置との誤差を補正する成形研削加工用ＮＣデータを与え、それにより砥石形状を諸元通りに整形するとともに、ワーク９を諸元通りに研削加工するようになっている。
【００６９】
上記構成を有するＮＣ研削加工装置による補正方法を下記（ｆ）〜（ｍ）のステップに分けて説明する。
【００７０】
（ｆ）ロータリドレッサ７の据え付け位置誤差ならび形状誤差と砥石歯形曲線誤差の幾何学的関係をモデル化する。このモデル化の手法は第一の形態と同じである。
【００７１】
( ｇ) ワーク諸元から与えられるワーク形状曲線に任意のワーク形状曲線座標系を与えて、このワーク形状曲線座標系内の任意の点と前記ワーク形状曲線との距離を計算する。
【００７２】
平歯車歯形を成形研削する場合のワーク９は円柱形をなしている。そこで、その円柱形状外周面をワーク形状曲線とし、円柱の中心を原点とした図１９に示すようなワーク形状曲線座標系を設定する。
【００７３】
ワーク形状曲線座標系における点（ｐ，ｑ）とワーク形状曲線（円柱外周）との距離ｄは、図２０より、
【００７４】
【数７】

【００７５】
という第１の式で与えられる。ここで、ｒ_w はワークの半径である。
【００７６】
( ｈ) 加工する砥石諸元および前記据え付け誤差及び形状誤差を含むモデルから与えられる砥石歯形曲線と合同である歯車歯形形状に任意の座標系を与えて、歯車歯形曲線と、前記歯車歯形曲線座標系内の任意の点との距離を計算する。
【００７７】
この距離の計算は第一の形態と同様であるが、第一の形態に対して本第二の形態では図２１に示すように、計測点がインボリュート曲線の外側にある。従って、式（５）は、
【００７８】
【数８】

【００７９】
という第２の式で示される。
【００８０】
（ｉ）ロータリドレッサ７付きＮＣ研削加工装置のＺ軸テーブル５に測定子８を取り付け、ロータリドレッサ７で整形した砥石６を用いて成形研削加工したワーク９の、ワーク外周部分９ａと歯車歯形部分９ｂとにそれぞれ測定子８を接触させた時のＮＣ駆動軸の値を計測し、計測結果をＮＣコントローラ２０の記憶手段２０ａに記憶する。
【００８１】
詳しくは図１７に示すように、ＮＣ研削加工装置のＺ軸テーブル５に、先端が球形からなる測定子８を取り付け、ＮＣ研削加工装置を動作させてワーク外周部分９ａと歯形部分９ｂ（インボリュート曲線部分）に測定子８を接触させる。本実施形態では、ＮＣ研削加工装置のＹ，Ｚ軸を動作させて、砥石６の整形部分を測定子８に接触させ、接触させた時のＮＣ駆動軸の値を計測する。
【００８２】
図２２に示すように、歯車歯形の左右をそれぞれＮ_Ｌｉ、Ｎ_Ｒｉ点計測し、これを、
【００８３】
【数９】

【００８４】
として記憶しておく。これらの計測データの値は、ＮＣ駆動軸座標系における、測定子８の中心位置とみなすことができる。
また、ワーク曲線である円柱外周部分をＮ_Ｗｉ点計測し、これを、
【００８５】
【数１０】

【００８６】
として記憶しておく。
【００８７】
（ｊ）ワーク９に測定子８を接触させたときの計測点とワーク形状曲線との距離が接触子球の半径になるように、上記ワーク形状曲線座標とＮＣ駆動軸座標の相対的位置関係を計算する。
【００８８】
図２３に示すように、ワーク形状曲線座標の原点位置( Ｙ_WO, Ｚ_WO) を座標変換パラメータとし、ワーク形状計測点χ_Wiとワーク形状曲線( 円柱外周) がフィットするように、すなわち、計測点とワーク形状曲線との距離が接触子球の半径になるように座標変換パラメータを求めれば、ＮＣ駆動軸座標とワーク形状曲線座標の相対的位置関係が導かれる。なお、計測点とワーク形状曲線をフィットさせるには、特開平９−１１０８５号公報に示した非線形の最小自乗法等を用いればよい。
【００８９】
（ｋ）歯車歯形に測定子８を接触させたときの計測点と歯形形状曲線との距離が接触子球の半径になるように、歯形形状曲線座標とＮＣ駆動軸座標の相対的位置関係、及び上述した（ｆ）項のモデル化で与えられた砥石歯形曲線誤差と等しい歯車歯形曲線誤差を計算する。この計算は、第一の形態の( ｄ) 項と同様の手法に従う。このときの歯車歯形曲線座標系とＮＣ駆動軸座標系との関係は図２４に示す通りである。
【００９０】
（ｌ）歯車歯形曲線誤差から、ロータリドレッサ７の据え付け位置誤差及び形状誤差を計算し、この誤差を補正する砥石整形ＮＣデータをＮＣ研削加工装置に与える。
この計算は第一の形態の（ｅ）項と同じ手法に従う。
【００９１】
（ｍ）ワーク形状曲線座標とＮＣ駆動軸座標の相対的位置関係並びに歯形形状曲線座標とＮＣ駆動軸座標の相対的位置関係から、ワーク形状曲線座標と歯形形状曲線座標の相対位置関係を計算し、目標とする相対位置との誤差を補正する成形研削加工用ＮＣデータを与え、砥石形状を諸元通りに整形加工すると共に、ワークを諸元通りに研削加工する。
【００９２】
上記ステップにより、ＮＣ駆動軸座標におけるワーク形状曲線座標の原点位置原点（Ｙ_ＷＯ，Ｚ_ＷＯ）と、ＮＣ駆動軸座標における歯形形状曲線座標の原点位置（Ｙ_ＧＬＯ，Ｚ_ＧＬＯ）が与えられる。ワークに対する研削形状の位置は加工諸元として与えらるものであり、本実施形態では、ワーク中心とインボリュート歯形の基礎円中心が一致すること、すなわち、座標（Ｙ_ＷＯ，Ｚ_ＷＯ）と座標（Ｙ_ＧＬＯ，Ｚ_ＧＬＯ）を一致させることが目標となり、この２つの原点位置誤差が、研削位置決め誤差になる。
【００９３】
図２５に示すように、形状誤差から砥石６の整形誤差を補正し、且つ研削位置誤差から砥石６の位置決め誤差を補正すれば、ワーク９に対する所定の部位に、目標通りの形状で成形研削加工を行うことが可能になる。
【００９４】
【発明の効果】
以上説明したことから明らかなように、本発明の砥石整形誤差補正方法およびその誤差補正装置によれば、砥石形状に誤差が含まれている場合に、その誤差を補正しつつ砥石形状を緒元通りに加工することができる。
【００９５】
また、本発明の砥石整形・直溝整形研削加工誤差補正方法及びその誤差補正装置によれば、砥石形状を緒元通りに加工するとともにワークを緒元通りに加工してワークの仕上げ精度を向上させることができるという長所を有する。
【図面の簡単な説明】
【図１】本発明の第一の形態に係る砥石整形誤差補正方法に使用するロータリドレッサ付きＮＣ研削加工装置の構成を示す斜視図である。
【図２】砥石整形時における砥石とロータリドレッサの配置を示す斜視図である。
【図３】砥石の整形状態を示す斜視図である。
【図４】ロータリドレッサの動作軌跡を示す説明図である。
【図５】インボリュート歯車歯形を説明する説明図である。
【図６】歯車におけるオフセット角度を示す説明図である。
【図７】オフセット角度の誤差を示す説明図である。
【図８】ロータリドレッサの回転軸芯誤差を説明する縦断面図である。
【図９】回転軸芯誤差を基礎円のずれで示した説明図である。
【図１０】砥石形状の計測状態を示す斜視図である。
【図１１】図１０の要部縦断面図である。
【図１２】砥石の計測点をＮＣ駆動軸座標系で示した説明図である。
【図１３】砥石断面形状曲線の座標系を示す説明図である。
【図１４】砥石断面形状曲線座標系における点と砥石断面形状曲線との距離の求め方を示す説明図である。
【図１５】ロータリドレッサの据え付け位置誤差の補正方法を示す説明図である。
【図１６】砥石の位置決め誤差有無を示す説明図である。
【図１７】本発明の第二の形態に係る砥石整形・直溝成形研削加工誤差補正方法に使用するロータリドレッサ付きＮＣ研削加工装置の構成を示す斜視図である。
【図１８】ワークの歯形部分の測定を示す要部説明図である。
【図１９】ワーク形状曲線座標系を示す説明図である。
【図２０】ワーク形状曲線座標系における点とワーク形状曲線との距離を示す説明図である。
【図２１】歯形形状曲線と歯形形状曲線座標系内の点との距離を示す説明図である。
【図２２】歯形形状の計測点を示す説明図である。
【図２３】ＮＣ駆動軸座標とワーク形状曲線座標との位置関係を示す説明図である。
【図２４】歯形形状曲線座標系とＮＣ駆動軸座標系との関係を示す説明図である。
【図２５】砥石整形誤差の補正から研削位置誤差の補正を行うに至るまでの処理手順を示す説明図である。
【符号の説明】
１ｘ軸テーブル
２割出台
３ワーク
４ｙ軸テーブル
５ｚ軸テーブル
６砥石
７ロータリドレッサ
７ａ整形用石
８測定子
９ワーク
９ａ非研削部分
９ｂ歯形部分[0001]
BACKGROUND OF THE INVENTION
The present invention measures the shape of a grindstone and the shape of a workpiece that has been formed and ground on a processing apparatus, and automatically creates correction machining NC data for machining the grindstone and workpiece as intended from the measurement result. It relates to a grinding wheel shaping error correction method, a grinding wheel shaping / straight groove forming grinding error correction method, and an error correction device for grinding and shaping straight grooves such as grinding wheels and involute spur gears without removing the workpiece from the machining device. is there.
[0002]
[Prior art]
There are two methods for grinding the gears: a creation method in which grinding is performed by meshing and moving a grinding wheel and a tooth surface, and a molding method in which grinding is performed while indexing teeth one by one using a grinding wheel having a shape that is congruent to the shape to be processed. However, the molding method has good grinding efficiency and is suitable for the production of a small variety of products because it can grind gears with any tooth profile. However, this molding method includes factors that depend on the processing accuracy of the product, for example, shaping errors in the grinding wheel, and errors in the relative positional relationship between the grinding wheel and the workpiece, compared to the creation method. How to correct the error is a problem in increasing the precision of the gear grinding.
[0003]
In addition, the NC forming grinding machine equipped with a grinding wheel shaping machine on the NC grinding machine can simultaneously perform grinding wheel shaping to grinding processing, so the trouble of changing the grinding wheel according to the workpiece machining shape In addition, since there is no attachment error associated with wheel replacement, it is expected that high-precision machining can be performed in a short time. However, in reality, the grindstone has not been machined into the target shape due to an installation position error of the grindstone shaping machine or a shape error due to wear or the like, and an error has occurred in the shape of the ground workpiece. Moreover, even if a grindstone shaped according to a target is used, the work cannot be machined into a target shape unless the whetstone mounting position is accurately given to the workpiece to be machined.
[0004]
Therefore, the inventor of the present invention has previously shown a method for correcting a position error of a grindstone with respect to a workpiece to be machined on an NC grinding machine in Japanese Patent Laid-Open No. 9-11085 (prior art). According to the correction method, a contact with a spherical tip is attached to the tool holder of the NC grinding machine, and the non-grinded part (workpiece outer peripheral surface) and the machined part (toothed surface) are measured to determine the known workpiece shape. In addition, the relative positional relationship between the workpiece shape coordinates and the machining shape coordinates in the NC grinding machine coordinates is determined so that the distance between the machining shape and the measurement data becomes the radius of the contact ball, and this and the target positional relationship This difference is taken as a machining tool positioning error, and NC machining data for correcting the error is given to the NC grinding machine so that machining as intended can be realized.
[0005]
[Problems to be solved by the invention]
However, since the above correction method is intended to improve the finishing accuracy of the gear on the assumption that the grindstone is shaped to the target shape, it is considered that the grindstone shape contains errors. Absent.
[0006]
The present invention has been made in consideration of the conventional problems as described above. When an error is included in the grindstone shape, the grindstone shape can be processed as it is while correcting the error. Further, a grinding wheel shaping error correction method and a grinding wheel shaping / straight groove forming grinding error correction method capable of improving the finishing accuracy of the workpiece by machining the grinding wheel shape according to the original shape and processing the workpiece according to the original shape, and Such an error correction apparatus is provided.
[0007]
[Means for Solving the Problems]
The grinding wheel shaping error correction method of the present invention is a method in which a probe having a known tip size is brought into contact with a shaping surface shaped by an NC grinding wheel shaping machine. NC drive shaft Measured coordinates, obtained by the measurement About measurement points Coordinate data is stored, and the geometric relationship of the grinding wheel cross-sectional shape curve error with respect to the installation position error and the shape error of the NC grinding wheel shaping machine is modeled, It is given from the model including the grinding wheel specifications to be machined and the installation position error and shape error. Any cross section shape curve Wheel cross-sectional shape curve Give the coordinate system, this Any point in the grinding wheel cross-sectional shape curve coordinate system The grinding wheel cross-sectional shape curve Distance to Find the expression that represents , Based on this formula, When the probe is brought into contact with the grindstone Said Measuring point and Said The distance from the grinding wheel cross-sectional shape curve , To be equal to the known dimension at the contact tip, Said Calculate the relative positional relationship between the NC drive axis coordinates and the grinding wheel cross-sectional shape curve coordinates, and the grinding wheel cross-sectional shape curve error given by the modeling, Said From the grinding wheel cross-sectional shape curve error, calculate the mounting position error and the shape error of the grinding wheel shaping machine, use the values to correct these errors as grinding wheel shaping NC data, and process the grinding wheel shape according to the specifications. To do.
[0008]
The grinding wheel shaping / straight groove forming grinding error correction method according to the present invention is a non-grinded portion of a workpiece obtained by forming and grinding a probe having a known tip dimension using a grinding wheel shaped by a grinding wheel shaping machine. And molding grinding part Each with a grinding groove When contacted NC drive shaft Measured coordinates, obtained by the measurement About measurement points Coordinate data is stored, and the geometric relationship of the grinding wheel cross-sectional shape curve error to the mounting position error and shape error of the grinding wheel shaping machine is modeled. About the non-grinded part given by workpiece specifications Any workpiece shape curve Work shape curve Give the coordinate system, this Any point in the workpiece shape curve coordinate system The workpiece shape curve and The distance Find the first expression to represent , It is given from the model including the grinding wheel specifications to be machined and the installation position error and shape error. Grinding groove cross-sectional shape that is congruent with the grinding wheel cross-sectional shape curve curve Any Grinding groove cross-sectional shape curve Give the coordinate system, this Any point in the grinding groove cross-sectional shape curve coordinate system The grinding groove cross-sectional shape curve and The distance Find the second expression to represent , Determined based on the first equation, The work Non-grinding part of When the probe is brought into contact with Said Measuring point and Said The distance from the workpiece shape curve is , The workpiece shape curve coordinates so as to be equal to the known dimension at the tip of the contact Said Calculate the relative positional relationship of NC drive axis coordinates, Obtained based on the second equation, When the probe is brought into contact with the grinding groove Said The distance between the measurement point and the grinding groove cross-sectional shape curve is , The grinding groove cross-sectional shape curve coordinates so as to be equal to the known dimension at the tip of the contact Said Relative positional relationship of NC drive axis coordinates and the modeling By Given the Equal to grinding wheel cross-sectional shape curve error Calculate grinding groove cross-sectional shape curve error, Said From the grinding groove cross-sectional shape error, the mounting position error and the shape error of the grinding wheel shaping machine are calculated, and values for correcting these errors are used as grinding wheel shaping NC data, and the workpiece shape curve coordinates and Said The relative positional relationship of the NC drive axis coordinates, and Said Grinding groove section shape curve coordinates and Said From the relative positional relationship of NC drive axis coordinates, Said Work shape curve coordinates and Said Calculate the relative positional relationship of the grinding groove cross-sectional shape curve coordinates, give NC data for forming grinding to correct the error with the target relative position, shape the grinding wheel shape according to the specifications, The gist is to perform grinding according to the specifications.
[0009]
The grindstone shaping error correction device of the present invention is obtained when a probe having a known tip size is brought into contact with a shaping surface shaped by an NC grindstone shaping machine. NC drive shaft Measurement means for measuring coordinates, and obtained by the measurement About measurement points Modeling the geometrical relationship between the storage means for storing the coordinate data and the grinding wheel cross-sectional shape curve error with respect to the installation position error and the shape error of the NC grinding wheel shaping machine; Given from the grinding wheel specifications to be processed and the model including the installation position error and shape error Any cross section shape curve Wheel cross-sectional shape curve Give the coordinate system, this Any point in the grinding wheel cross-sectional shape curve coordinate system The grinding wheel cross-sectional shape curve and Calculate the distance of Calculation Means, Calculated by this calculation means, When the probe is brought into contact with the grindstone Said The distance between the measurement point and the wheel cross-sectional shape curve is , To be equal to the known dimension at the contact tip, Said Means for calculating the relative positional relationship between the NC drive axis coordinates and the grinding wheel cross-sectional shape curve coordinates, and the grinding wheel cross-sectional shape curve error given by the modeling; Said From the grinding wheel cross-sectional shape curve error, calculating the mounting position error and the shape error of the grinding wheel shaping machine, using a value for correcting these errors as grinding wheel shaping NC data, a correction means for processing the grinding wheel shape according to the specifications, The gist is that
[0010]
The grinding wheel shaping / straight groove forming grinding error correction apparatus according to the present invention is a non-grinding of a workpiece obtained by forming and grinding a measuring element having a known tip dimension using a grinding wheel shaped by an NC grinding wheel shaping machine. Part and molded grinding part Each with a grinding groove When contacted NC drive shaft Measurement means for measuring coordinates, and obtained by the measurement About measurement points Modeling the geometric relationship of the grinding wheel cross-sectional shape curve error with respect to the storage means for storing the coordinate data and the mounting position error and the shape error of the grinding wheel shaping machine; Given from work specifications Any workpiece shape curve Work shape curve Give the coordinate system, this Any point in the workpiece shape curve coordinate system The workpiece shape curve and Calculate the distance of As well as the specifications of the wheel to be machined and the error Grinding groove cross-sectional shape that is congruent with the grinding wheel cross-sectional shape curve curve Any Grinding groove cross-sectional shape curve Give the coordinate system, this Any point in the grinding groove cross-sectional shape curve coordinate system The grinding groove cross-sectional shape curve and A calculation means for calculating the distance of Calculated by this calculation means, The work Non-grinding part of When the probe is brought into contact with Said Measuring point and Said The distance from the workpiece shape curve is , The workpiece shape curve coordinates so as to be equal to the known dimension at the tip of the contact Said Means for calculating the relative positional relationship of the NC drive axis coordinates; Obtained by the calculating means, When the probe is brought into contact with the grinding groove Said The relative positional relationship between the grinding groove cross-sectional shape curve coordinate and the NC drive axis coordinate and the modeling so that the distance between the measurement point and the grinding groove cross-sectional shape curve is equal to the known dimension at the tip of the contact By Given the Equal to grinding wheel cross-sectional shape curve error Means for calculating grinding groove cross-sectional shape curve error; Said From the grinding groove cross-sectional shape error, the mounting position error and the shape error of the grinding wheel shaping machine are calculated, and values for correcting these errors are used as grinding wheel shaping NC data, and the workpiece shape curve coordinates and Said The relative positional relationship of the NC drive axis coordinates, and Said Grinding groove section shape curve coordinates and Said From the relative positional relationship of NC drive axis coordinates, Said Work shape curve coordinates and Said Calculate the relative positional relationship of the grinding groove cross-sectional shape curve coordinates, give NC data for forming grinding to correct the error with the target relative position, thereby shaping the grinding wheel shape according to the specifications, The gist of the invention is that it comprises a correcting means for grinding according to the specifications.
[0011]
In the error correction method and the error correction apparatus of the present invention, the measuring element is preferably provided on the base of the NC grindstone shaping machine or the grindstone holding part.
[0012]
In the present invention, the non-grinding part and the molded grinding part mean the outer periphery (corresponding to the tooth tip circle) and the tooth profile of the work when the work is used for grinding gears, for example. In the above gear example, it is assumed that the center of the gear tip circle is equal to the center of the gear, and the center of the workpiece is obtained by measuring the outer peripheral portion of the workpiece. Include any shape on the workpiece that can determine the center of the workpiece. Therefore, the center of the workpiece can be obtained not only by the outer peripheral portion but also by measuring the inner peripheral portion of the hole in a workpiece in which a hole is accurately drilled with respect to the center.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.
In addition, although this invention is not limited to the shape of a grindstone or a workpiece | work, in the following embodiment, the shaping | molding grinding process of an involute spur gear is demonstrated to an example as a typical example of a straight groove forming grinding process. In the description, (1) after explaining the grinding wheel shaping error correction method and the error correction device used therefor as the first form, (2) as the second form, the grinding wheel shaping / form grinding processing error compensation method and the error used therefor. The correction device will be described.
[0014]
First, the configuration of a five-axis NC gear grinding apparatus (hereinafter simply referred to as an NC grinding apparatus) with a multi-stone rotary grindstone shaping machine used in the first and second embodiments will be described with reference to FIG. .
[0015]
In the figure, the x-axis table 1 reciprocates in the left-right direction (x-axis direction), and the work holding portion 2a of the index base 2 rotates around the A axis while holding the work 3. It has become.
[0016]
The y-axis table 4 moves forward or backward in the front-rear direction (y-axis direction), and a z-axis table 5 that can be moved up and down in the vertical direction (z-axis direction) is provided on the y-axis table 4. It has been. A grindstone holding portion 5a is provided on the front surface of the z-axis table 5, and a grindstone 6 shaped in the shape of a tooth groove of a work gear is pivotally supported at the tip of the grindstone holding portion 5a.
[0017]
Reference numeral 7 denotes a multi-stone rotary grindstone shaping machine (hereinafter referred to as a rotary dresser) attached to the base of the NC grinding apparatus.
[0018]
The storage means 10a of the NC controller 10 stores coordinate data measured by a probe that will be described later. The measuring element and the NC controller 10 can be regarded as measuring means.
[0019]
The distance calculation means 10b models the geometric relationship of the grinding wheel cross-sectional shape curve error (explained as a grinding wheel tooth profile curve error in this embodiment) with respect to the installation position error and shape error of the rotary dresser 7. Also , Given by the model including the grinding wheel specifications and errors to be machined Any grinding wheel profile Wheel tooth profile curve Give the coordinate system, this Any point in the grinding wheel curve coordinate system Grinding wheel tooth profile curve And calculate the distance.
[0020]
The grinding wheel tooth profile curve error calculating means 10c It is calculated | required by the said distance detection means 10b. The relative positional relationship between the NC drive axis coordinates and the grinding wheel tooth profile curve coordinates so that the distance between the measurement point when the measuring tool is brought into contact with the grinding wheel 6 and the grinding wheel tooth profile curve is equal to the known dimension at the tip of the contact; Calculate the grinding wheel profile curve error given by modeling.
[0021]
The correction means 10d calculates an installation position error and a shape error of the rotary dresser 7 from the grinding wheel tooth profile curve error, uses values for correcting these errors as the grinding wheel shaping NC data, and processes the grinding wheel shape according to the specifications. It is like that.
[0022]
In forming grinding of a spur gear tooth profile by the NC grinding machine with a rotary dresser having such a configuration, first, as shown in FIG. 2, the NC drive shaft is operated to push the grindstone 6 against the rotating rotary dresser 7. The grinding stone 6 is shaped by the contact. FIG. 3 shows a state in which the grindstone 6 is moved from one side of the rotary dresser 7 to the other side to shape the right and left sides of the grindstone, and 7a is a shaping stone.
[0023]
In FIG. 1, in order to explain an embodiment related to grinding wheel shaping and shaping grinding correction, which will be described later, a configuration of an apparatus that can also perform shaping grinding of a tooth profile is shown. However, in the first embodiment, only grinding stone shaping error correction is handled. Therefore, for example, an NC grinder without a tooth profile grinding function may be used.
[0024]
FIG. 4 shows an operation trajectory of the rotary dresser 7 with respect to the grindstone 6 during shaping of the grindstone. A shaping stone 7a made of diamond or the like is fixed to the edge of the rotary dresser 7, and the operation of the rotary dresser 7 is given as an operation reference point e. Then, the grindstone 6 is shaped by operating the motion reference point e with the grindstone curve f.
[0025]
Specifically, by giving the radius rd of the shaping stone 7a to the NC controller 10 as a tool radius correction value with respect to the locus of the grinding stone curve f, the operation reference point e is equal to the shaping stone radius rd from the grinding stone curve f. As a result, the grindstone 6 is shaped according to the target grindstone curve f.
[0026]
Next, the grindstone shaping correction method according to the first embodiment will be described by dividing it into the steps (a) to (e).
[0027]
(A) Model the geometric relationship of the grinding wheel tooth profile curve error to the rotary dresser installation position error and shape error.
[0028]
In the rotary dresser 7, the radius rd of the shaping stone 7a changes due to secular change or the like and deviates from the value initially set in the NC controller 10 (shape error), and the rotary shaft core of the rotary dresser 7 is NC processed. In some cases, the grindstone 6 cannot be shaped as intended.
[0029]
First, the influence of the error of the shaping stone radius rd on the grindstone shape will be considered. The involute gear tooth profile uses a part of the involute curve shown in FIG. 5 for the tooth profile curve, but in an actual gear, as shown in FIG. 6, the involute offset angle θ according to the tooth thickness. ₀ (Starting angle of involute curve) is specified. In this case, the error of the shaping stone radius rd is the involute offset angle θ as shown in FIG. ₀ Cause an error.
[0030]
FIG. 4A shows a case where there is no error in the shaping stone radius rd, and FIG. 4B shows a case where an error occurs in the shaping stone radius rd. That is, when the error between the normal value and the actual value is Δrd and Δθ0, respectively, in the shaping stone radius and the involute offset angle,
[0031]
[Expression 1]

[0032]
Given in. Here, rg is the involute basic half circle.
[0033]
Next, the influence of the rotational axis error of the rotary dresser 7 on the grindstone shape will be considered.
[0034]
Normally, the rotational axis error is considered to be very small, but if an error occurs in the rotational axis, a difference in height occurs between the right and left edges of the rotary dresser 7 as shown in FIG. If the grinding wheel shaping is performed in this state, as shown in FIG. 9, it can be seen that although the offset angle of the involute is equal, the height of the center of the basic circle is different on the left and right. That is, when the difference in the height direction at the center of the involute foundation circle is Δhg and the difference in height between the left and right edges of the rotary dresser 7 is Δhd,
[0035]
[Expression 2]

[0036]
Given in.
[0037]
As described above, the geometric relationship of the grindstone curve error with respect to the installation position error and the shape error of the rotary dresser 7 is modeled.
[0038]
(B) The value of the NC drive shaft when the probe 8 having a spherical tip is attached to the base of the rotary dresser 7 with NC, and the probe 8 is brought into contact with the grindstone 6 shaped by the rotary dresser 7 with NC. And the measurement result is stored in the storage means 10a of the NC controller 10.
[0039]
In the arrangement shown in FIG. 10, the rotary dresser 7 with NC is operated, and the measuring element 8 is brought into contact with the shaping portion of the grindstone 6 as shown in FIG. 11. Specifically, in the present embodiment, the Y and Z axes of the NC grinding apparatus are operated, the shaping portion of the grindstone 6 is brought into contact with the measuring element 8, and the value of the NC drive shaft when contacting is measured. . That is, as shown in FIG. _Li , N _Ri Point measurement, this,
[0040]
[Equation 3]

[0041]
Remember as. These measurement data values can be regarded as the center position of the probe 8 in the NC drive axis coordinate system. The measuring element 8 in the present embodiment uses an arbitrary sensor such as a touch sensor or an electric microsensor as long as it has a function of converting the displacement and contact of the tip into a voltage signal and outputting the voltage signal. be able to.
[0042]
(c) Given from the grinding wheel specifications and the model including the installation error and shape error Any grinding wheel profile Wheel tooth profile curve Given a coordinate system, this Any point in the grinding wheel curve coordinate system The grinding wheel tooth profile curve and Calculate the distance.
[0043]
From the above, even if the installation error of the rotary dresser 7 and the shape error of the grindstone 6 are included, the shape of the involute curve does not change, only the offset angle of the involute and the height of the center of the left and right basic circles. You can see that it changes. Therefore, as shown in FIG. 13, the coordinate system of the grindstone curve is set at the position where the involute offset angle is “0” for the grindstone shape including the error.
[0044]
Even if there is a grinding wheel shaping error, the grinding wheel tooth profile curve in the grinding wheel tooth profile curve coordinate system is invariant, and the coordinate of the coordinate system with respect to the reference coordinate (in the NC drive axis coordinate system) where the horizontal axis is Y and the vertical axis is Z The position of the origin and the direction of the coordinate axis change.
[0045]
Next, referring to FIG. 14, the distance between the point (p, q) in the grinding wheel tooth profile coordinate system and the grinding wheel tooth profile curve (involute curve) is calculated. From the geometric relationship shown in the figure,
[0046]
[Expression 4]

[0047]
It becomes. Using this θ, the distance d between the point (p, q) and the grindstone curve (involute curve) is
[0048]
[Equation 5]

[0049]
Formula Given in.
[0050]
(d) Obtained by the above formula, The relative positional relationship between the NC drive axis coordinates and the grinding wheel tooth profile curve coordinates and the above so that the distance between the measurement point when the measuring tool 8 is brought into contact with the grinding wheel 6 and the grinding wheel tooth profile curve become the radius of the contact ball. Calculate the grinding wheel profile curve error given in the modeling of step (a).
[0051]
As shown in FIG. 14, by taking the grinding wheel tooth profile curve coordinates, the grinding wheel tooth profile curve error is not reflected in this coordinate system (the grinding wheel tooth profile curve is unchanged). Therefore, the relative relationship between the NC drive axis coordinate and the grinding wheel tooth profile curve coordinate is shown. Only the positional relationship needs to be considered.
[0052]
Specifically, the origin position (Y of the grinding wheel tooth profile curve coordinates on the left side shown in FIG. _GLO , Z _GLO ), The height error Δh at the center of the left and right basic circles _g , Offset angle error Δθ ₀ If the coordinate conversion parameter is calculated so that the measurement point and the grinding wheel tooth profile curve fit, that is, the distance between the measurement point and the grinding wheel tooth profile curve becomes the radius rd of the contact ball, the NC drive axis coordinates And the relative positional relationship of the grindstone curve coordinates. In addition, as a method of fitting the measurement point and the grindstone tooth profile curve, a non-linear least square method described in JP-A-9-11085 can be used.
[0053]
In this way, the origin position (Y _GLO , Z _GLO ) And the height error Δh at the center of the left and right basic circles, which is a shape error _g And offset angle error Δθ ₀ Is guided.
[0054]
(E) An installation position error and a shape error of the rotary dresser 7 are calculated from the shape error, and grinding wheel shaping NC data for correcting this error is given to the NC controller 10.
[0055]
From the above formulas (1) and (2), the relationship between the installation error of the rotary dresser 7 and the shape error with respect to the shape error is given.
[0056]
[Formula 6]

[0057]
Thus, the installation position error and the shape error of the rotary dresser 7 can be calculated from the shape error.
[0058]
The shaping stone diameter rd of the rotary dresser 7 deviates from the value initially given to the NC controller 10 (shape error), and the rotational axis of the rotary dresser 7 deviates from the vertical axis of the NC grinding apparatus ( For example, as shown in FIG. 15, the grindstone 6 is not formed as intended. However, by correcting the installation position error and the shape error of the rotary dresser 7 by the above-described method, specifically, the installation is performed. Regarding the position error correction, when the left side of the grindstone 6 is shaped, the NC trajectory to be shaped is shifted by the height error on the left and right. In addition, regarding the shape error correction, by subtracting the shaping stone error from the current tool radius correction value, the target grindstone 6 is shaped (see FIG. 15B).
Next, the grinding wheel shaping / formation grinding correction method according to the second embodiment will be described.
[0059]
A case will be described in which a spur gear tooth profile is formed and ground after the grinding wheel is shaped using the 5-axis NC grinding apparatus with the rotary dresser 7 shown in FIG.
[0060]
In forming grinding of a spur gear tooth profile, as shown in FIG. 16 (a), the target tooth profile is not obtained until the grindstone 6 is accurately positioned with respect to the center of the workpiece 9 (the center of the workpiece and the center of the involute base circle are aligned). Can be obtained. However, since there is an NC drive shaft positioning error in actual machining, the center of the workpiece 9 and the center of the involute base circle do not coincide with each other as shown in FIG.
[0061]
In prior art Japanese Patent Laid-Open No. 9-11085, as shown in FIG. 17, a probe 8 having a spherical tip is attached to a Z-axis table 5 in an NC grinding apparatus, and the probe 8 is attached to a non-ground portion 9a ( The positioning error of the grindstone 6 was corrected using the value of the NC drive shaft when it was brought into contact with the outer peripheral portion of the workpiece and the forming grinding portion 9b (tooth profile portion). However, since this correction method does not consider the shaping error of the grindstone 6, if the grindstone 6 contains a shaping error, an error occurs in the correction of the positioning error between the workpiece 9 and the grindstone 6.
[0062]
If the correction described in JP-A-9-11085 is performed after the grinding wheel has been accurately shaped by the method described in the first embodiment, more accurate tooth profile grinding can be realized. In this case, two measuring elements for measuring the grindstone shape and for measuring the workpiece tooth profile are required, resulting in a redundant system. Therefore, in the present invention, the shaping error of the grindstone 6 and the positioning error of the grindstone 6 with respect to the work 9 can be corrected at a time by measuring the shape of the workpiece that has been formed and ground.
[0063]
FIG. 17 shows the configuration of the correction device used in the second embodiment. The same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.
[0064]
In the figure, the storage means 20a of the NC controller 20 is a work outer peripheral portion of a work 9 formed and ground using a grindstone 6 shaped by a rotary dresser 7. (Non-ground part) 9a and gear tooth profile (Grinding groove) Coordinate data obtained by bringing the probe 8 into contact with 9b is stored.
[0065]
The distance calculating means 20b models the geometric relationship of the grinding wheel tooth profile curve error with respect to the installation position error and the shape error of the rotary dresser 7, About the workpiece outer peripheral portion 9a given from the workpiece specifications Any workpiece shape curve Work shape curve Give the coordinate system, this Any point in the workpiece shape curve coordinate system The workpiece shape curve and Calculate the distance. Also, Given from the grinding wheel specifications and the model including the installation error and shape error Gear tooth profile that is congruent with the grinding wheel profile curve Any Gear tooth profile curve Give the coordinate system, this Any point in the gear tooth profile coordinate system and The gear tooth profile curve and Calculate the distance.
[0066]
Also, The workpiece outer peripheral portion 9b The relative positional relationship between the workpiece shape curve coordinates and the NC drive axis coordinates is calculated so that the distance between the measurement point and the workpiece shape curve when the measurement piece 8 is brought into contact with the contact piece sphere becomes the radius of the contact sphere.
[0067]
The gear tooth profile curve error calculating means 20c is arranged so that the gear tooth profile curve coordinates and the NC drive shaft are such that the distance between the measurement point and the gear tooth profile curve when the measuring element 8 is brought into contact with the gear tooth profile surface is the radius of the contact ball. Relative position of coordinates and given by modeling method Equal to grinding wheel profile curve error Calculate the gear tooth profile curve error.
[0068]
The correction means 20d calculates an installation position error and a shape error of the rotary dresser 7 from the gear tooth profile shape error, and uses a value for correcting these errors as the grinding wheel shaping NC data, using the workpiece shape curve coordinates and the NC drive axis coordinates. The relative position relationship between the workpiece shape curve coordinate and the gear tooth profile curve coordinate is calculated from the relative position relationship between the gear tooth profile curve coordinate and the NC drive axis coordinate, and the error from the target relative position is corrected. NC data for forming grinding is given, whereby the shape of the grindstone is shaped according to the specifications, and the workpiece 9 is ground according to the specifications.
[0069]
The correction method using the NC grinding apparatus having the above-described configuration will be described in the following steps (f) to (m).
[0070]
(F) The geometrical relationship between the installation position error of the rotary dresser 7, the shape error, and the grindstone curve error is modeled. This modeling method is the same as in the first embodiment.
[0071]
(g) Given from work specifications Any workpiece shape curve Work shape curve Given a coordinate system, this Any point in the workpiece shape curve coordinate system The workpiece shape curve and Calculate the distance.
[0072]
The workpiece 9 in the case of forming and grinding the spur gear tooth profile has a cylindrical shape. Therefore, a workpiece shape curve coordinate system as shown in FIG. 19 is set with the cylindrical outer peripheral surface as the workpiece shape curve and the center of the cylinder as the origin.
[0073]
The distance d between the point (p, q) in the workpiece shape curve coordinate system and the workpiece shape curve (cylinder outer periphery) is
[0074]
[Expression 7]

[0075]
The first expression Given in. Where r _w Is the radius of the workpiece.
[0076]
(h) Given from the grinding wheel specifications and the model including the installation error and shape error An arbitrary coordinate system is given to the gear tooth profile that is congruent with the grinding wheel tooth profile curve, and the distance between the gear tooth profile curve and an arbitrary point in the gear tooth profile curve coordinate system is calculated.
[0077]
The calculation of this distance is the same as in the first embodiment, but in the second embodiment, the measurement point is outside the involute curve as shown in FIG. Therefore, equation (5) becomes
[0078]
[Equation 8]

[0079]
The second expression Indicated by
[0080]
(I) A workpiece outer peripheral portion 9a and a gear tooth profile portion of a workpiece 9 which is formed and ground by using a grindstone 6 attached to a probe 8 on a Z-axis table 5 of an NC grinding processing apparatus with a rotary dresser 7 and shaped by the rotary dresser 7. The value of the NC drive shaft when the probe 8 is brought into contact with 9b is measured, and the measurement result is stored in the storage means 20a of the NC controller 20.
[0081]
Specifically, as shown in FIG. 17, a probe 8 having a spherical tip is attached to the Z-axis table 5 of the NC grinding machine, and the NC grinding machine is operated to operate the workpiece outer peripheral portion 9 a and the tooth profile portion 9 b (involute curve). The probe 8 is brought into contact with the portion. In the present embodiment, the Y and Z axes of the NC grinding apparatus are operated so that the shaping portion of the grindstone 6 is brought into contact with the measuring element 8, and the value of the NC drive shaft when it is brought into contact is measured.
[0082]
As shown in FIG. _Li , N _Ri Point measurement, this,
[0083]
[Equation 9]

[0084]
Remember as. These measurement data values can be regarded as the center position of the probe 8 in the NC drive axis coordinate system.
Also, the outer peripheral part of the cylinder that is the work curve is represented by N _Wi Point measurement, this,
[0085]
[Expression 10]

[0086]
Remember as.
[0087]
(J) Relative positional relationship between the workpiece shape curve coordinate and the NC drive axis coordinate so that the distance between the measurement point and the workpiece shape curve when the measuring piece 8 is brought into contact with the workpiece 9 becomes the radius of the contact sphere. Calculate
[0088]
As shown in FIG. 23, the origin position of the workpiece shape curve coordinates (Y _WO , Z _WO ) As a coordinate transformation parameter, shape Measurement point χ _Wi If the coordinate conversion parameters are determined so that the distance between the measurement point and the workpiece shape curve becomes the radius of the contactor sphere, the NC drive axis coordinates and the workpiece shape curve The relative positional relationship of the coordinates is derived. In order to fit the measurement point and the workpiece shape curve, a non-linear least square method or the like disclosed in JP-A-9-11085 may be used.
[0089]
(K) Relative positional relationship between the tooth profile curve coordinates and the NC drive axis coordinates so that the distance between the measurement point and the tooth profile curve when the contact 8 is brought into contact with the gear tooth profile is the radius of the contact ball, And given by the modeling of (f) term above Equal to grinding wheel profile curve error Calculate the gear tooth profile curve error. This calculation follows the same method as the (d) term of the first form. The relationship between the gear tooth profile curve coordinate system and the NC drive axis coordinate system at this time is shown in FIG. In As shown.
[0090]
(L) An installation position error and a shape error of the rotary dresser 7 are calculated from the gear tooth profile curve error, and grinding wheel shaping NC data for correcting this error is given to the NC grinding apparatus.
This calculation follows the same method as in the first form (e).
[0091]
(M) Calculate the relative positional relationship between the work shape curve coordinate and the tooth profile curve coordinate from the relative positional relationship between the workpiece shape curve coordinate and the NC drive axis coordinate and the relative position relationship between the tooth profile curve coordinate and the NC drive axis coordinate. Then, NC data for forming grinding for correcting an error from the target relative position is given, and the grinding wheel shape is shaped according to the specifications, and the workpiece is ground according to the specifications.
[0092]
By the above steps, the origin position origin (Y) of the workpiece shape curve coordinates in the NC drive axis coordinates _WO , Z _WO ) And the origin position of the tooth profile curve coordinates in the NC drive axis coordinates (Y _GLO , Z _GLO ) Is given. The position of the grinding shape with respect to the workpiece is given as a machining specification. In this embodiment, the center of the workpiece and the base circle center of the involute tooth profile coincide, that is, the coordinate (Y _WO , Z _WO ) And coordinates (Y _GLO , Z _GLO ) To coincide with each other, and these two origin position errors become grinding positioning errors.
[0093]
As shown in FIG. 25, if the shaping error of the grindstone 6 is corrected from the shape error, and the positioning error of the grindstone 6 is corrected from the grinding position error, the forming grinding process is performed in a predetermined shape with respect to the workpiece 9 in a target shape. It becomes possible to do.
[0094]
【The invention's effect】
As is apparent from the above description, according to the grinding wheel shaping error correction method and the error correction device of the present invention, when an error is included in the grinding wheel shape, the grinding wheel shape is corrected while correcting the error. Can be processed to the street.
[0095]
Moreover, according to the grinding wheel shaping / straight groove shaping grinding error correction method and the error correction device of the present invention, the grinding wheel shape is machined according to the specifications, and the workpiece is machined according to the specifications, thereby improving the finishing accuracy of the workpiece. It has the advantage that it can be made.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of an NC grinding apparatus with a rotary dresser used in a grinding wheel shaping error correction method according to a first embodiment of the present invention.
FIG. 2 is a perspective view showing the arrangement of a grindstone and a rotary dresser during grinding wheel shaping.
FIG. 3 is a perspective view showing a shaping state of a grindstone.
FIG. 4 is an explanatory diagram showing an operation locus of a rotary dresser.
FIG. 5 is an explanatory diagram for explaining an involute gear tooth profile;
FIG. 6 is an explanatory diagram showing an offset angle in a gear.
FIG. 7 is an explanatory diagram showing an error of an offset angle.
FIG. 8 is a longitudinal sectional view for explaining a rotational axis error of a rotary dresser.
FIG. 9 is an explanatory diagram showing a rotation axis error by a deviation of a basic circle.
FIG. 10 is a perspective view showing a measurement state of a grindstone shape.
11 is a longitudinal sectional view of a main part of FIG.
FIG. 12 is an explanatory view showing measurement points of a grindstone in an NC drive axis coordinate system.
FIG. 13 is an explanatory diagram showing a coordinate system of a grindstone cross-sectional shape curve.
FIG. 14 is an explanatory diagram showing how to obtain a distance between a point in a grindstone cross-sectional shape curve coordinate system and a grindstone cross-sectional shape curve.
FIG. 15 is an explanatory diagram showing a method for correcting a rotary dresser installation position error;
FIG. 16 is an explanatory diagram showing presence / absence of a positioning error of a grindstone.
FIG. 17 is a perspective view showing the configuration of an NC grinding apparatus with a rotary dresser used in the grinding wheel shaping / straight groove forming grinding error correction method according to the second embodiment of the present invention.
FIG. 18 is a main part explanatory view showing measurement of a tooth profile portion of a workpiece.
FIG. 19 is an explanatory diagram showing a workpiece shape curve coordinate system.
FIG. 20 is an explanatory diagram showing a distance between a point in the workpiece shape curve coordinate system and the workpiece shape curve.
FIG. 21 is an explanatory diagram showing a distance between a tooth profile curve and a point in the tooth profile curve coordinate system;
FIG. 22 is an explanatory diagram showing measurement points of a tooth profile shape.
FIG. 23 is an explanatory diagram showing a positional relationship between NC drive axis coordinates and workpiece shape curve coordinates;
FIG. 24 is an explanatory diagram showing the relationship between the tooth profile curve coordinate system and the NC drive axis coordinate system.
FIG. 25 is an explanatory diagram showing a processing procedure from correction of a grinding wheel shaping error to correction of a grinding position error.
[Explanation of symbols]
1 x-axis table
2 Index stand
3 Work
4 y-axis table
5 z-axis table
6 Whetstone
7 Rotary dresser
7a Orthopedic stone
8 Measuring element
9 Work
9a Unground part
9b Tooth profile

Claims

Measure the NC drive axis coordinates when a measuring element whose tip size is known is brought into contact with the shaping surface shaped by the NC grinding wheel shaping machine,
Storing coordinate data about the measurement points obtained by the measurement ;
Modeling the geometric relationship of the grinding wheel cross-sectional shape curve error to the installation position error and shape error of the NC grinding wheel shaping machine,
Giving any grindstone sectional shape curvilinear coordinates the grindstone sectional shape curve given from a model that includes a grinding wheel for machining specifications and the mounting position error and shape errors, the any point grindstone in the grinding sectional shape curvilinear coordinates Find the formula that expresses the distance from the cross-sectional shape curve ,
Is obtained on the basis of the equation, as the distance between the grinding wheel cross section curve and the measurement points upon contacting the measuring element to said grinding wheel becomes equal to the known dimensions of the contact tip, the NC Calculate the relative positional relationship between the drive axis coordinates and the grinding wheel cross-sectional shape curve coordinates, and the grinding wheel cross-sectional shape curve error given by the modeling,
From the grinding wheel cross-sectional shape curve error, an installation position error and a shape error of the grinding wheel shaping machine are calculated, and values for correcting these errors are used as grinding wheel shaping NC data to process the grinding wheel shape according to specifications. A grinding wheel shaping error correction method.

When a measuring element whose tip size is known is brought into contact with a non-grinded part and a grinding groove, which is a molded grinding part , of a workpiece that has been shaped and ground using a grinding wheel shaped by a grinding wheel shaping machine. Measure NC drive axis coordinates,
Storing coordinate data about the measurement points obtained by the measurement ;
Modeling the geometric relationship of the grinding wheel cross-sectional shape curve error to the grinding wheel shaping machine installation position error and shape error,
Giving any workpiece shape curvilinear coordinate system the given from the work specifications to the work shape curve for the non-grinding part, the first representing the distance between any point in the work shape curve coordinate system and the workpiece shape curve Find the formula
Giving any grinding groove cross-sectional shape curvilinear coordinates the grinding groove cross section curve is congruent with grindstone sectional shape curve given from a model that includes a grinding wheel specification and the mounting position error and shape error processing, the grinding groove cross-sectional shape Obtain a second expression representing the distance between an arbitrary point in the curved coordinate system and the grinding groove cross-sectional shape curve
Is determined based on the first equation, the distance between the workpiece shape curve and the measurement points upon contacting the measuring element in the unground portion of the workpiece is equal to the known dimensions of the contact tip so as to calculates the relative positional relationship of the said workpiece shape curve coordinate NC drive axis coordinate,
Is determined based on the second equation, the distance between the grinding groove cross section curve and the measurement points upon contacting the measuring element in the grinding groove is equal to the known dimensions of the contact tip as such, with the grinding groove cross section curve coordinate and relative positions of the NC drive axis coordinate, equal grinding groove cross section curves error and given grindstone sectional shape curve error by the modeling calculations,
From the grinding groove sectional shape errors, a mounting position error sequence shape error of the grinding wheel shaper calculates, using the values to correct these errors as the grindstone shaping NC data, the workpiece shape curve coordinates of the NC drive shaft coordinates relative positional relationship, and the grinding of the groove cross section curve coordinate the relative positional relationship of the NC drive shaft coordinates, to calculate the relative positional relationship between said workpiece shape curve coordinate with the grinding groove cross section curve coordinate, the target NC data for forming grinding that corrects the error with the relative position is given, so that the shape of the grinding wheel is shaped according to the specifications and the grinding of the workpiece according to the specifications is corrected. Method.

The error correction method according to claim 1 or 2, wherein the measuring element is provided on a base of an NC grindstone shaping machine.

The error correction method according to claim 2, wherein the workpiece is processed into a gear, the non-grinding portion is an outer peripheral portion of a cylindrical workpiece, and the forming grinding portion is a tooth profile portion.

A measuring means for measuring an NC drive axis coordinate when a probe having a known tip dimension is brought into contact with a shaping surface shaped by an NC grindstone shaping machine;
Storage means for storing coordinate data about the measurement points obtained by the measurement ;
The geometric relationship of the grinding wheel cross-sectional shape curve error with respect to the installation position error and the shape error of the NC grinding wheel shaping machine is modeled, and the grinding wheel cross-sectional shape curve given from the grinding wheel specifications to be processed and the model including the installation position error and the shape error a calculating means for calculating the distance between the grinding wheel cross section curve and any point in any given grinding sectional shape curvilinear coordinate system, the grinding wheel cross section curve coordinate system,
Obtained by this computing means, so that the distance between the measuring point and the grindstone sectional shape curve when contacting the measuring element to said grinding wheel becomes equal to the known dimensions of the contact tip, the NC drive shaft A relative positional relationship between coordinates and the grinding wheel cross-sectional shape curve coordinates, means for calculating a grinding wheel cross-sectional shape curve error given by the modeling,
From the grindstone sectional shape curve error, the installation position error and the shape error of the grinding wheel shaper calculates, using the values to correct these errors as the grindstone shaping NC data, and correction means for processing the grindstone shape on various restore ,
A grindstone shaping error correction device comprising:

When a probe whose tip size is known is brought into contact with the non-grinded part and the grinding groove, which is the part of the grinding process, of the workpiece that has been shaped and ground using the grinding wheel shaped by the NC grinding wheel shaping machine. Measuring means for measuring the NC drive axis coordinates of
Storage means for storing coordinate data about the measurement points obtained by the measurement ;
Modeling the geometric relationship of the grinding wheel cross-sectional shape curve error with respect to the mounting position error and shape error of the grinding wheel shaping machine, giving an arbitrary workpiece shape curve coordinate system to the workpiece shape curve given from the workpiece specifications , and this workpiece shape curve Calculates the distance between an arbitrary point in the coordinate system and the workpiece shape curve, and arbitrarily calculates the grinding groove sectional shape curve that is congruent to the grinding wheel sectional shape curve given from the grinding wheel specifications and the model including the error . given grinding groove sectional shape curvilinear coordinate system, and calculating means for calculating a distance between any point in this grinding groove sectional shape curvilinear coordinate system and the grinding groove cross section curve,
Obtained by this computing means, so that the distance between the measurement points upon contacting the measuring element in the unground portion of the workpiece and the workpiece shape curve, equal to the known dimensions of the contact tip, means for calculating a relative positional relationship of the NC drive axis coordinate and the workpiece shape curve coordinates,
The obtained by the calculation means, so that the distance between the grinding groove cross section curve and the measurement points upon contacting the measuring element in the grinding groove is equal to the known dimensions of the contact tip, the ground means for calculating a relative positional relation of the groove cross-sectional shape curve coordinates and NC drive axis coordinate, equal grinding groove cross section curves error and given grindstone sectional shape curve error by the modeling,
From the grinding groove sectional shape errors, a mounting position error sequence shape error of the grinding wheel shaper calculates, using the values to correct these errors as the grindstone shaping NC data, the workpiece shape curve coordinates of the NC drive shaft coordinates relative positional relationship, and the grinding of the groove cross section curve coordinate the relative positional relationship of the NC drive shaft coordinates, to calculate the relative positional relationship between said workpiece shape curve coordinate with the grinding groove cross section curve coordinate, the target NC data for forming and grinding that corrects an error from the relative position is provided, thereby correcting the shape of the grindstone according to the specifications, and correcting means for grinding the workpiece according to the specifications;
A grinding wheel shaping / straight groove forming grinding error correction device characterized by comprising:

The error correction device according to claim 5 or 6, wherein the measuring element is provided in a grindstone holding portion.

The error correction apparatus according to claim 6, wherein the workpiece is processed into a gear, the non-ground portion is an outer peripheral portion of a cylindrical workpiece, and the forming and grinding portion is a tooth profile portion.