JP4326774B2

JP4326774B2 - Honing processing method and apparatus

Info

Publication number: JP4326774B2
Application number: JP2002295319A
Authority: JP
Inventors: 春彦二井谷; 敬紀山本; 啓史川原
Original assignee: Toyo Advanced Technologies Co Ltd
Current assignee: Toyo Advanced Technologies Co Ltd
Priority date: 2002-10-08
Filing date: 2002-10-08
Publication date: 2009-09-09
Anticipated expiration: 2022-10-08
Also published as: JP2004130404A

Description

【０００１】
【発明の属する技術分野】
本発明は、ワークに形成された円筒状内周面をホーニング加工するための方法及び装置に関するものである。
【０００２】
【従来の技術】
従来、ワークの円筒状内周面内で砥石を拡径させながら加工を進めるものとしては、例えば特許文献１に示されるように、まず前記各砥石を十分に縮径させて円筒状内周面の内側に挿入した状態から予め設定された初期拡径速度で前記各砥石を拡径させ、これらの砥石と前記円筒状内周面とが接触してその接触圧が一定以上になった時点で砥石拡径速度を前記初期拡径速度よりも低い加工用速度に下げて当該円筒状内周面の径が目標径に達するまで加工を進めるものが知られている。
【０００３】
【特許文献１】
特開平５−３１８３０８号公報
【０００４】
【発明が解決しようとする課題】
前記のように砥石拡径速度を一定に制御する方法では、ワーク内周面の加工しろ及び性状が一定であれば、加工終了時における砥石接触圧もほぼ一定に収まることになるが、実際には前記加工しろや性状にバラツキがあるため、加工終了時の砥石接触圧にも相当バラツキが生じることになる。このような最終接触圧のバラツキは、当該接触圧によるワークの拡径方向の弾性変形量のバラツキや摩擦による発熱量のバラツキにつながり、ひいては最終加工径のバラツキすなわち品質安定化の妨げとなるので、最終接触圧を安定させることが重要な課題となる。
【０００５】
本発明は、このような事情に鑑み、加工終了時の砥石接触圧のバラツキを抑えて品質の安定化を図ることができるホーニング加工方法及び装置を提供することを目的とする。
【０００６】
【課題を解決するための手段】
前記課題を解決するための手段として、本発明は、複数の砥石が周方向に並べられかつ径方向に出没可能に装着されたホーニングツールを用い、その各砥石がワークの円筒状内周面に接触するように砥石径を拡大した状態で前記ホーニングツールを軸方向に往復移動させかつ回転駆動することにより上記円筒状内周面を加工するホーニング加工方法において、前記各砥石と前記円筒状内周面との接触圧またはこれに相当する値を検出するとともに、当該各砥石が前記円筒状内周面から内方に離間した状態から予め設定された初期拡径速度で前記砥石径を拡大するとともに、その拡大中に当該各砥石と前記円筒状内周面との接触圧またはこれに相当する値の検出値と予め設定された第１の接触圧相当値とを対比する初期拡径工程と、前記各砥石と前記円筒状内周面との接触圧またはこれに相当する値の検出値が予め設定された第１の接触圧相当値に達した時点から前記砥石径の拡大速度を前記初期拡径速度よりも低い第１の加工用拡径速度に下げて当該円筒状内周面の加工を進めるとともに、その加工中に前記各砥石と前記円筒状内周面との接触圧またはこれに相当する値の検出値と前記第１の接触圧相当値よりも高い値であって予め設定された第２の接触圧相当値とを対比する第１加工工程と、この第１加工工程において前記検出値が前記第２の接触圧相当値に達した時点から前記砥石径の拡大速度を前記第１の加工用拡径速度よりも低い第２の加工用拡径速度に下げて当該円筒状内周面の加工を進める第２加工工程とを行い、かつ、前記円筒状内周面の径が目標径に達した時点で加工を終了する当該各砥石が前記円筒状内周面から内方に離間した状態から予め設定された初期拡径速度で前記砥石径を拡大する初期拡径工程と、当該各砥石と前記円筒状内周面との接触圧またはこれに相当する値の検出値が予め設定された第１の接触圧相当値に達した時点から前記砥石径の拡大速度を前記初期拡径速度よりも低い第１の加工用拡径速度に下げて当該円筒状内周面の加工を進める第１加工工程と、この第１加工工程において前記各砥石と前記円筒状内周面との接触圧またはこれに相当する値の検出値が前記第１の接触圧相当値よりも高い第２の接触圧相当値に達した時点から前記砥石径の拡大速度を前記第１の加工用拡径速度よりも低い第２の加工用拡径速度に下げて当該円筒状内周面の加工を進める第２加工工程とを含み、かつ、前記円筒状内周面の径が目標径に達した時点で加工を終了するものである。
【０００７】
また本発明は、複数の砥石が周方向に並べられかつ径方向に出没可能に装着されたホーニングツールと、その砥石径を拡縮させる砥石径操作手段とを備え、前記各砥石がワークの円筒状内周面に接触する状態で前記ホーニングツールが円筒状内周面に対して軸方向に往復移動しかつ回転することにより当該円筒状内周面を加工するホーニング加工装置において、当該各砥石と前記円筒状内周面との接触圧またはこれに相当する値を検出する検出手段と、その検出値に基づいて前記砥石径の拡縮操作を制御する制御手段とを備え、この制御手段は、前記各砥石が前記円筒状内周面から内方に離間した状態から予め設定された初期拡径速度で前記各砥石を拡径させるとともに、その拡径中に当該各砥石と前記円筒状内周面との接触圧またはこれに相当する値の検出値と予め設定された第１の接触圧相当値とを対比する初期拡径操作と、前記検出手段による検出値が前記第１の接触圧相当値に達した時点から前記各砥石の拡径速度を前記初期拡径速度よりも低い第１の加工用拡径速度に下げて当該円筒状内周面の加工を進めるとともに、その加工中に前記各砥石と前記円筒状内周面との接触圧またはこれに相当する値の検出値と前記第１の接触圧相当値よりも高い値であって予め設定された第２の接触圧相当値とを対比する第１加工用拡径操作と、この第１加工用拡径操作により前記各砥石と前記円筒状内周面との接触圧またはこれに相当する値が前記第２の接触圧相当値に達した時点から前記各砥石の拡径速度を前記第１の加工用拡径速度よりも低い第２の加工用拡径速度に下げて当該円筒状内周面の加工を進める第２加工用拡径操作とを含む拡径操作を前記砥石径操作手段に行わせ、前記円筒状内周面の径が目標径に達した時点で拡径操作を終了させるものである。
【０００８】
これらの方法及び装置では、初期拡径速度で各砥石をワークの円筒状内周面に接触させてから砥石接触圧またはそれに相当する値が第１の接触圧相当値に達した時点でいきなり砥石拡径速度を最終速度まで下げる従来技術と異なり、接触圧相当値に応じて少なくとも第１の加工用拡径速度への切換及び第２の加工用拡径速度への切換を含む複数段階の速度切換を経てから加工終了に至るようにしているので、前記従来技術のように接触圧相当値に基づく拡径速度切換が１回のみのものに比べて加工終了時における砥石接触圧のバラツキが有効に削減され、これにより品質の安定化（特に最終加工径の寸法の安定化）が果たされる。
【０００９】
【発明の実施の形態】
本発明の好ましい実施の形態を図１〜図３に基づいて説明する。
【００１０】
図２に示すホーニング加工装置は、ホーニングツールの本体軸１０と、この本体軸１０内に格納される砥石操作軸２０と、砥石操作軸２０を本体軸１０に対して相対移動させる操作軸昇降装置３０とを備え、これら砥石操作軸２０及び操作軸昇降装置３０により、砥石径を拡縮させる砥石径操作手段が構成されるとともに、その砥石径拡縮操作が制御装置（制御手段）４０により制御されるようになっている。
【００１１】
本体軸１０は、その上側部分が中実軸１２、下部が下方に開口する筒状の中空軸１４となっており、この中空軸１４内に前記砥石操作軸２０が軸方向に移動可能（図では昇降可能）に格納されている。一方、前記中実軸１２には鍔部１２ａが形成され、その直上方の部分が軸受５２を介して支持フレーム５０側に回転可能に支持されるとともに、当該中実軸１２に本体軸１０を高速回転駆動するための図略の回転駆動モータが連結されている。この回転駆動モータ及び前記支持フレーム５０は、加工中、本体軸１０と一体に図略のワークの軸方向すなわち本体軸１０の軸方向に往復駆動されるようになっている。
【００１２】
前記本体軸１０の下端部には、周方向に並ぶ複数の窓１４ａが形成され、各窓１４ａ内に砥石保持部材１５が装填されており、各砥石保持部材１５の外側面に砥石１８が固着されている。砥石保持部材１５は各窓１４ａ内で本体軸１０の径方向にスライド可能であり、各砥石保持部材１５の内側面１５ａは下方に向かうに従って本体軸１０の中心に近付く向きに傾斜するテーパー面とされている。
【００１３】
これに対し、前記砥石操作軸２０の下端部には、前記砥石保持部材内側面１５ａに合致するテーパー状外周面をもった（すなわち先尖り円錐状の）砥石径操作部２２が形成されている。そして、この砥石径操作部２２が本体軸１０に対して相対的に先端側へ移動する（図では降下する）ことにより、各砥石保持部材１５が径方向外側に押し出されて砥石径（周方向に並ぶ砥石１８の外接円の直径）が拡大されるようになっている。
【００１４】
この砥石操作軸２０の上端部は、前記操作軸昇降装置３０により保持され、かつ、昇降操作されるようになっている。その詳細を図３に示す。
【００１５】
前記砥石操作軸２０の上端にはこれを径方向に貫通するようにピン２６が固定され、このピン２６の両端が、前記中空軸１４の上端部に形成された軸方向の貫通長孔１３を通じて当該中空軸１４の外周面から径方向外側に突出している。そして、これらの突出端部が前記砥石操作軸２０を取り巻く円筒状のリング２８に固定されている。
【００１６】
一方、操作軸昇降装置３０の本体は、前記本体軸１０の周囲に軸方向に移動可能に配設される円筒ハウジング３２と、この円筒ハウジング３２から側方に延びるアーム３３とで構成され、前記円筒ハウジング３２内には、前記リング２８を前記砥石操作軸２０回りに相対回転可能となるように保持する上下一対のスラスト軸受３１が組み込まれている。この構造により、砥石操作軸２０が操作軸昇降装置３０側に相対回転可能に保持されるとともに、この操作軸昇降装置３０と一体に本体軸１０に対して前記貫通長孔１３の長さ分だけ相対的に昇降できるようになっている。
【００１７】
さらに、前記円筒ハウジング３２の天壁下面と上側のスラスト軸受３１との間にはロードセル（検出手段）５４が設けられ、このロードセル５４により、前記各砥石保持部材１５から砥石操作軸２０が受ける上向きの反力、ひいては、砥石１８とワークの円筒状内周面との接触圧Ｐに相当する力が検出されるようになっている。
【００１８】
なお、本発明においてホーニングツールやその砥石径操作手段の具体的構成は特に問わず、従来から知られている種々の構成を適用することができる。
【００１９】
図２に示すように、前記アーム３３にはナット３４が固定され、これに上下方向に延びる送りねじ軸３５が螺合されている。この送りねじ軸３５には、前記支持フレーム５０側に固定された砥石径操作モータ３６が連結されており、同モータ３６によって前記送りねじ軸３５が回転駆動されることにより、前記アーム３３と一体に前記円筒ハウジング３２さらには前記砥石操作軸２０が昇降駆動されるようになっている。
【００２０】
制御装置４０は、前記ロードセル５４の検出信号から求められる砥石接触圧Ｐと、図略の加工径検出手段により検出されるワークの内周面加工径とに基づき、前記砥石操作軸２０の昇降駆動の制御、すなわち、砥石径拡縮操作の制御を行うように構成されている。
【００２１】
ここで、前記加工径検出手段は、前記本体軸１０の下端部に組み込まれたもの（例えば本体軸１０の下端部からワーク内周面にエアを噴射してその圧力を検出するもの）でもよいし、当該本体軸１０とは別に設置されるものでもよい。従来からホーニング加工等において使用されている周知のものをそのまま適用することが可能である。
【００２２】
次に、前記制御装置４０の具体的な制御動作も含め、前記ホーニング加工装置により行われるホーニング加工方法を図１（ａ）のグラフも併せて参照しながら説明する。
【００２３】
まず、本体軸１０に対して砥石操作軸２０を引き上げて砥石径を十分縮径させた状態で、本体軸１０の下端部をワークの円筒状内周面の内側に挿入する。そして、前記本体軸１０を高速回転駆動し、かつ、軸方向に往復動させながら、予め設定された初期拡径速度Ｖ０で砥石径が拡大するような速度で砥石操作軸２０を本体軸１０に対して相対的に下降させる。
【００２４】
具体的に、制御装置４０は、前記砥石径操作モータ３６に対して前記初期拡径速度Ｖ０に対応した速度指令信号を入力し、これを受けた砥石径操作モータ３６が前記速度指令信号に対応した速度で送りねじ軸３５を回転駆動する。これによってアーム３３、円筒ハウジング３２、及び砥石操作軸２０が一体に降下し、当該砥石操作軸２０の下端の砥石操作部２２のテーパー状外周面が各砥石保持部材１５のテーパー状内周面１５ａを内側から押圧することにより各砥石保持部材１５が径方向外側にスライドして砥石径（各砥石１８の外接円の直径）が前記初期拡径速度Ｖ０で拡大される。このとき、砥石操作軸２０が各砥石保持部材１５から受ける反力はハウジング３２内のロードセル５４により検出され、制御装置４０に入力される。
【００２５】
このような初期拡径操作が進んで各砥石１８がワークの円筒状内周面に接触し始めると、その接触圧Ｐが急激に上昇し、ひいてはロードセル５４により検出される値（すなわち砥石操作軸２０が各砥石保持部材１５から受ける上向きの反力の検出値）が急激に高まる。ここで、制御装置４０は、当該検出値を監視し、当該検出値が予め設定された第１の接触圧相当値（予め設定された砥石接触圧Ｐ１に相当する値）に達した時点で（図１（ａ）の時刻ｔ１）、砥石拡径速度をそれまでの初期拡径速度Ｖ０から第１の加工用拡径速度Ｖ１（＜Ｖ０）に下げる。この第１の加工用拡径速度Ｖ１は、この実施の形態では、前記初期拡径速度Ｖ０よりは低いが、当該速度での砥石径の拡径に伴って砥石接触圧Ｐが増加する程度の速度に設定されている。
【００２６】
このような第１の加工用拡径操作により、ワーク内周面の除去加工が進められるが、当該拡径操作により前記ロードセル５４の検出値が第２の接触圧相当値（前記砥石接触圧Ｐ１よりも高い砥石接触圧Ｐ２に相当する値）に達した時点で（図１（ａ）の時刻ｔ２）、砥石拡径速度をそれまでの第１の加工用拡径速度Ｖ１からさらにそれよりも低い第２の加工用拡径速度Ｖ２に下げる。この第２の加工用拡径速度Ｖ２は、この実施の形態では、当該速度での砥石径の拡径にかかわらず砥石接触圧Ｐがほぼ一定に保たれるような速度に設定されている。
【００２７】
一方、前記制御装置４０は加工径検出手段により検出される加工径（加工されているワーク内周面の直径）を監視しており、この加工径が予め設定された径に到達した時点で（図１（ａ）の時刻ｔ３）、砥石径拡大操作を停止させる。
【００２８】
以上示した方法及び装置によれば、砥石１８がワーク内周面に接触した時点で砥石径の拡径速度を初期拡径速度からいきなり最終拡径速度Ｖ２まで下げるのではなく、当該最終拡径速度Ｖ２よりも高い拡径速度Ｖ１である程度加工を行ってから当該拡径速度Ｖ２に下げるようにしているので、加工終了時における砥石接触圧のバラツキを小さく抑えることができる。
【００２９】
すなわち、図１（ｂ）に示すように、初期拡径速度Ｖ０で砥石径を拡大して砥石接触圧がＰ２に達した時点（時刻ｔ１′）で直ちに最終拡径速度Ｖ２まで拡径速度を下げる従来方法では、その拡径速度を下げた時点、換言すれば、砥石接触圧Ｐ２が検出された時点から加工終了時までの経過時間が長いため、当該加工終了までに砥石接触圧Ｐが前記接触圧Ｐ２から外れる度合い、すなわちバラツキΔＰが大きくなるのに対し、図１（ａ）に示した方法では、砥石接触圧Ｐが前記接触圧Ｐ２に到達する前に前記最終拡径速度Ｖ２よりも高い拡径速度Ｖ１でワーク内周面の加工をある程度進めているので、前記接触圧Ｐ２が検出された時点から加工終了時間での経過時間を短くすることができ、その分、加工終了時における砥石接触圧ＰのバラツキΔＰを抑えることが可能となるのである。
【００３０】
なお、この実施の形態では拡径速度を２段階に切換えるものを示したが、３段階以上に切換える構成としてもよい。すなわち、最終拡径速度を前記第２の加工用拡径速度よりも低い第３、あるいは第４の加工用拡径速度に設定してもよい。要は、拡径速度として少なくとも初期拡径速度、第１の加工用拡径速度、第２の加工用拡径速度を含んでいればよい。
【００３１】
また、最終拡径速度は、前記のように砥石接触圧を一定に保つような速度に限られず、当該砥石接触圧が少し上昇する程度の高めの速度、あるいは砥石接触圧が少し下降する程度の低めの速度に設定してもよい。
【００３２】
さらに、各拡径速度は必ずしも固定された速度でなくてもよく、ワーク加工の度に補正されるものでもよい。例えば、加工終了時における砥石接触圧Ｐあるいはその変動率が許容範囲よりも外れる場合には、これを許容範囲内に収めるように次のワーク加工時における拡径速度を補正するようにしてもよい。
【００３３】
【発明の効果】
以上のように本発明は、ワーク内周面の加工を終了する前に、砥石径拡大速度の切換を少なくとも第１の加工用拡径速度への切換及び第２の加工用拡径速度への切換を含む複数段階にわたって行うようにしたものであるので、ワーク加工終了時における砥石接触圧のバラツキを抑えて品質を安定化させることができる効果がある。
【図面の簡単な説明】
【図１】（ａ）は本発明の実施の形態にかかるホーニング加工方法での砥石接触圧の時間変化を示すグラフ、（ｂ）は従来のホーニング加工方法での砥石接触圧の時間変化を示すグラフである。
【図２】本発明の実施の形態にかかるホーニング加工装置の一部断面正面図である。
【図３】前記ホーニング加工装置における砥石径操作手段の要部を示す一部断面正面図である。
【符号の説明】
１０本体軸
１８砥石
２０砥石操作軸（砥石径操作手段）
３０操作軸昇降装置（砥石径操作手段）
４０制御装置（制御手段）
５４ロードセル（検出手段）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for honing a cylindrical inner peripheral surface formed on a workpiece.
[0002]
[Prior art]
Conventionally, as to advance the processing while expanding the diameter of the grindstone within the cylindrical inner peripheral surface of the workpiece, for example, as shown in Patent Document 1, first, each of the grindstones is sufficiently reduced in diameter to form a cylindrical inner peripheral surface. When the diameter of each of the grindstones is increased at a preset initial diameter-expanding speed from the state of being inserted inside, and when the grindstone comes into contact with the cylindrical inner peripheral surface and the contact pressure becomes a certain level or more, It is known that the grindstone diameter expansion speed is lowered to a machining speed lower than the initial diameter expansion speed and the machining is advanced until the diameter of the cylindrical inner peripheral surface reaches a target diameter.
[0003]
[Patent Document 1]
JP-A-5-318308 [0004]
[Problems to be solved by the invention]
As described above, in the method of controlling the grinding wheel diameter expansion rate to a constant value, if the machining margin and properties of the workpiece inner peripheral surface are constant, the grinding wheel contact pressure at the end of machining will be almost constant. Since there are variations in the machining margins and properties, the whetstone contact pressure at the end of machining also varies considerably. Such variations in the final contact pressure lead to variations in the amount of elastic deformation of the workpiece in the direction of diameter expansion due to the contact pressure and variations in the amount of heat generated due to friction, which in turn hinders variations in the final machining diameter, that is, quality stabilization. Stabilizing the final contact pressure is an important issue.
[0005]
In view of such circumstances, an object of the present invention is to provide a honing method and apparatus capable of stabilizing the quality by suppressing variation in the grindstone contact pressure at the end of processing.
[0006]
[Means for Solving the Problems]
As means for solving the above-mentioned problems, the present invention uses a honing tool in which a plurality of grindstones are arranged in the circumferential direction and mounted so as to be able to protrude and retract in the radial direction, and each grindstone is provided on the cylindrical inner peripheral surface of the workpiece. In the honing method for machining the cylindrical inner peripheral surface by reciprocating and rotating the honing tool in the axial direction in a state in which the grindstone diameter is expanded so as to come into contact with each of the grindstones and the cylindrical inner circumference It detects the contact pressure or a value corresponding thereto to the surface, together with the respective grinding wheel for enlarging the grinding wheel diameter preset initial diameter speed from separated state inwardly from the cylindrical inner peripheral surface The initial diameter expansion step of comparing the contact pressure between each of the grindstones and the cylindrical inner peripheral surface during the expansion or a detected value of a value corresponding thereto with a preset first contact pressure equivalent value ; each of the grinding wheel From the point in time when the contact pressure with the cylindrical inner peripheral surface or the detected value of the value corresponding thereto reaches a preset first contact pressure equivalent value, the grinding wheel diameter expansion speed is set higher than the initial diameter expansion speed. The machining of the cylindrical inner peripheral surface is advanced to a lower first expansion diameter for machining, and the contact pressure between each grindstone and the cylindrical inner peripheral surface or a value corresponding thereto is detected during the machining. a first processing step of comparing the second contact pressure equivalent value set in advance a value higher than the value first contact pressure equivalent value, is pre-dangerous detection value in the first processing step the cylindrical inner peripheral surface is lowered prior Symbol second machining diameter speed lower than the expansion speed of the first machining diameter speed of the grinding wheel diameter from the time it reaches the second contact pressure equivalent value And when the diameter of the cylindrical inner peripheral surface reaches the target diameter. An initial diameter expansion step of expanding the diameter of the grindstone at a preset initial diameter expansion speed from a state in which each of the grindstones to finish the work is spaced inward from the cylindrical inner peripheral surface, and each grindstone and the cylindrical shape A first lowering speed of the grindstone diameter than the initial diameter-expanding speed from a point in time when the contact pressure with the inner peripheral surface or the detected value corresponding to this reaches a preset first contact pressure-corresponding value. A first machining step in which the machining of the cylindrical inner peripheral surface is carried out by lowering the machining expansion speed, and a contact pressure between the grindstone and the cylindrical inner peripheral surface in the first machining step or the equivalent. When the detected value of the value reaches a second contact pressure equivalent value that is higher than the first contact pressure equivalent value, a second speed at which the grinding wheel diameter enlargement speed is lower than the first machining diameter enlargement speed. A second machining step that advances the machining of the cylindrical inner peripheral surface by lowering the machining expansion rate, And processing is complete | finished when the diameter of the said cylindrical internal peripheral surface reaches a target diameter.
[0007]
The present invention also includes a honing tool in which a plurality of grindstones are arranged in the circumferential direction and mounted so as to be able to protrude and retract in the radial direction, and grindstone diameter operating means for expanding and contracting the grindstone diameter, and each of the grindstones is a cylindrical shape of a workpiece. In the honing apparatus that processes the cylindrical inner peripheral surface by reciprocating and rotating the honing tool in the axial direction with respect to the cylindrical inner peripheral surface in a state in contact with the inner peripheral surface, A detecting means for detecting a contact pressure with the cylindrical inner peripheral surface or a value corresponding thereto, and a control means for controlling an expansion / contraction operation of the grindstone diameter based on the detected value. While expanding the diameter of each grindstone at a preset initial diameter expansion speed from a state in which the grindstone is spaced inward from the cylindrical inner peripheral surface , the grindstone and the cylindrical inner peripheral surface during the diameter expansion Contact pressure or this Initial diameter operations and for comparing the first contact pressure equivalent value set in advance and the detected value of the value equivalent to the from the time when the value detected by the detection means reaches the first contact pressure equivalent value each The grinding wheel diameter expansion speed is lowered to the first machining diameter expansion speed lower than the initial diameter expansion speed to advance the processing of the cylindrical inner peripheral surface, and the grinding wheel and the cylindrical inner periphery are processed during the processing. The first processing expansion for comparing the detected value of the contact pressure with the surface or a value corresponding thereto with a preset second contact pressure equivalent value that is higher than the first contact pressure equivalent value. and径操operation, each grinding wheel from the time when the contact pressure or a value corresponding thereto of the respective grinding wheel and the cylindrical inner peripheral surface reaches the second contact pressure equivalent value by the first processing diameter operation Is reduced to a second machining expansion speed lower than the first machining expansion speed. A diameter expansion operation including a second diameter expansion operation for advancing the processing of the cylindrical inner peripheral surface is performed by the grindstone diameter operating means, and the diameter is increased when the diameter of the cylindrical inner peripheral surface reaches a target diameter. The operation is terminated.
[0008]
In these methods and apparatuses, the grindstone suddenly comes into contact with the grindstone contact pressure or a value corresponding to the first contact pressure after contacting each grindstone with the cylindrical inner peripheral surface of the workpiece at the initial diameter expansion speed. Unlike the prior art that lowers the diameter expansion speed to the final speed, the speed in multiple stages including switching to at least the first machining diameter expansion speed and switching to the second machining diameter expansion speed in accordance with the contact pressure equivalent value Since the process is completed after the switching, the variation in the grinding wheel contact pressure at the end of machining is more effective than the one in which the diameter expansion speed switching based on the contact pressure equivalent value is performed only once as in the prior art. Thus, the quality is stabilized (in particular, the final processed diameter is stabilized).
[0009]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of the present invention will be described with reference to FIGS.
[0010]
The honing apparatus shown in FIG. 2 includes a main body shaft 10 of a honing tool, a grindstone operation shaft 20 stored in the main body shaft 10, and an operation shaft lifting device that moves the grindstone operation shaft 20 relative to the main body shaft 10. 30, and the grindstone operating shaft 20 and the operation shaft lifting / lowering device 30 constitute a grindstone diameter manipulating means for expanding and contracting the grindstone diameter, and the grindstone diameter expanding / contracting operation is controlled by the control device (control means) 40. It is like that.
[0011]
The main body shaft 10 has a solid shaft 12 at its upper portion and a cylindrical hollow shaft 14 whose lower portion opens downward, and the grindstone operating shaft 20 can move in the axial direction within this hollow shaft 14 (see FIG. Can be moved up and down). On the other hand, a flange 12a is formed on the solid shaft 12, and a portion immediately above the flange 12a is rotatably supported on the support frame 50 side via a bearing 52, and the body shaft 10 is attached to the solid shaft 12. A rotation drive motor (not shown) for high-speed rotation drive is connected. The rotary drive motor and the support frame 50 are reciprocally driven integrally with the main body shaft 10 in the axial direction of the workpiece (not shown), that is, the axial direction of the main body shaft 10 during processing.
[0012]
A plurality of windows 14 a arranged in the circumferential direction are formed at the lower end portion of the main body shaft 10, and a grindstone holding member 15 is loaded in each window 14 a, and the grindstone 18 is fixed to the outer surface of each grindstone holding member 15. Has been. The grindstone holding member 15 is slidable in the radial direction of the main body shaft 10 in each window 14a, and the inner side surface 15a of each grindstone holding member 15 has a tapered surface that inclines toward the center of the main body shaft 10 as it goes downward. Has been.
[0013]
On the other hand, at the lower end of the grindstone operating shaft 20, a grindstone diameter manipulating portion 22 having a tapered outer peripheral surface that matches the inner surface 15a of the grindstone holding member (that is, a pointed cone) is formed. . Then, the grindstone diameter operating portion 22 moves toward the tip side relative to the main body shaft 10 (lowers in the drawing), whereby each grindstone holding member 15 is pushed radially outward and the grindstone diameter (circumferential direction). The diameter of the circumscribed circle of the grindstones 18 arranged in a row is expanded.
[0014]
The upper end of the grindstone operating shaft 20 is held by the operating shaft lifting device 30 and is lifted and lowered. The details are shown in FIG.
[0015]
Pins 26 are fixed to the upper end of the grindstone operating shaft 20 so as to penetrate the wheel shaft 20 in the radial direction, and both ends of the pin 26 pass through an axial through-hole 13 formed at the upper end of the hollow shaft 14. Projecting radially outward from the outer peripheral surface of the hollow shaft 14. These protruding end portions are fixed to a cylindrical ring 28 surrounding the grindstone operating shaft 20.
[0016]
On the other hand, the main body of the operating shaft lifting / lowering device 30 is composed of a cylindrical housing 32 disposed so as to be movable in the axial direction around the main body shaft 10 and an arm 33 extending laterally from the cylindrical housing 32. In the cylindrical housing 32, a pair of upper and lower thrust bearings 31 for holding the ring 28 so as to be relatively rotatable around the grindstone operating shaft 20 are incorporated. With this structure, the grindstone operating shaft 20 is held on the operating shaft lifting / lowering device 30 side so as to be relatively rotatable, and is integrated with the operating shaft lifting / lowering device 30 to the main body shaft 10 by the length of the through long hole 13. It can be moved up and down relatively.
[0017]
Further, a load cell (detecting means) 54 is provided between the lower surface of the top wall of the cylindrical housing 32 and the upper thrust bearing 31, and the load cell 54 causes the grindstone operating shaft 20 to receive upward from each grindstone holding member 15. Reaction force, and thus, a force corresponding to the contact pressure P between the grindstone 18 and the cylindrical inner peripheral surface of the workpiece is detected.
[0018]
In the present invention, the specific configuration of the honing tool and the grindstone diameter operating means is not particularly limited, and various conventionally known configurations can be applied.
[0019]
As shown in FIG. 2, a nut 34 is fixed to the arm 33, and a feed screw shaft 35 extending in the vertical direction is screwed to the nut 34. The feed screw shaft 35 is connected to a grindstone diameter operating motor 36 fixed to the support frame 50 side, and the feed screw shaft 35 is rotationally driven by the motor 36 so as to be integrated with the arm 33. Further, the cylindrical housing 32 and the grindstone operating shaft 20 are driven up and down.
[0020]
The controller 40 drives the grindstone operating shaft 20 to move up and down based on the grindstone contact pressure P obtained from the detection signal of the load cell 54 and the inner peripheral surface machining diameter of the workpiece detected by a machining diameter detecting means (not shown). Control, that is, control of the grinding wheel diameter expansion / contraction operation.
[0021]
Here, the machining diameter detection means may be one incorporated in the lower end portion of the main body shaft 10 (for example, one that detects the pressure by injecting air from the lower end portion of the main body shaft 10 to the inner peripheral surface of the work). However, it may be installed separately from the main body shaft 10. It is possible to apply a known one that has been conventionally used in honing and the like.
[0022]
Next, the honing method performed by the honing device including the specific control operation of the control device 40 will be described with reference to the graph of FIG.
[0023]
First, the lower end portion of the main body shaft 10 is inserted inside the cylindrical inner peripheral surface of the workpiece while the grindstone operating shaft 20 is pulled up with respect to the main body shaft 10 to sufficiently reduce the diameter of the grindstone. Then, the grindstone operating shaft 20 is moved to the main body shaft 10 at a speed at which the grindstone diameter is enlarged at a preset initial diameter expansion speed V0 while the main body shaft 10 is driven to rotate at high speed and reciprocally move in the axial direction. Lower relative to it.
[0024]
Specifically, the control device 40 inputs a speed command signal corresponding to the initial diameter-expanding speed V0 to the grindstone diameter operating motor 36, and the grindstone diameter operating motor 36 receiving the speed command signal corresponds to the speed command signal. The feed screw shaft 35 is rotationally driven at the determined speed. As a result, the arm 33, the cylindrical housing 32, and the grindstone operating shaft 20 are integrally lowered, and the tapered outer peripheral surface of the grindstone operating portion 22 at the lower end of the grindstone operating shaft 20 is a tapered inner peripheral surface 15 a of each grindstone holding member 15. Is pressed from the inside to slide each of the grindstone holding members 15 radially outward, and the grindstone diameter (diameter of the circumscribed circle of each grindstone 18) is expanded at the initial diameter expansion speed V0. At this time, the reaction force that the grindstone operating shaft 20 receives from each grindstone holding member 15 is detected by the load cell 54 in the housing 32 and input to the control device 40.
[0025]
When such an initial diameter expansion operation proceeds and each grindstone 18 starts to contact the cylindrical inner peripheral surface of the workpiece, the contact pressure P increases rapidly, and eventually the value detected by the load cell 54 (that is, the grindstone operation shaft). The detection value of the upward reaction force 20 receives from each grindstone holding member 15) increases rapidly. Here, the control device 40 monitors the detected value, and when the detected value reaches a preset first contact pressure equivalent value (a value corresponding to the preset grindstone contact pressure P1) ( At time t1) in FIG. 1 (a), the grindstone diameter expansion speed is lowered from the initial diameter expansion speed V0 to the first machining diameter expansion speed V1 (<V0). In this embodiment, the first machining diameter expansion speed V1 is lower than the initial diameter expansion speed V0, but the grinding wheel contact pressure P increases as the grinding wheel diameter increases at the speed. The speed is set.
[0026]
The removal processing of the inner peripheral surface of the workpiece is advanced by such a first diameter expansion operation for machining, and the detected value of the load cell 54 is set to a second contact pressure equivalent value (the grindstone contact pressure P1) by the diameter expansion operation. (A value corresponding to a higher grinding wheel contact pressure P2) (time t2 in FIG. 1 (a)), the grinding wheel diameter increasing speed is further increased from the first working diameter expanding speed V1. Lower to a low second expansion diameter V2 for processing. In the present embodiment, the second machining diameter-expanding speed V2 is set to a speed at which the grindstone contact pressure P is maintained substantially constant regardless of the diameter-expanding of the grindstone diameter at that speed.
[0027]
On the other hand, the control device 40 monitors the machining diameter detected by the machining diameter detecting means (the diameter of the workpiece inner peripheral surface), and when this machining diameter reaches a preset diameter ( At time t3 in FIG. 1A, the grindstone diameter expanding operation is stopped.
[0028]
According to the method and apparatus described above, when the grindstone 18 comes into contact with the inner peripheral surface of the workpiece, the diameter expansion speed of the grindstone is not suddenly decreased from the initial diameter expansion speed to the final diameter expansion speed V2, but the final diameter expansion. Since the machining is performed to some extent at the diameter expansion speed V1 higher than the speed V2, the diameter is reduced to the diameter expansion speed V2, so that the variation in the grindstone contact pressure at the end of the machining can be suppressed to be small.
[0029]
That is, as shown in FIG. 1 (b), when the wheel diameter is increased at the initial diameter expansion speed V0 and the wheel contact pressure reaches P2 (time t1 '), the diameter expansion speed is immediately increased to the final diameter expansion speed V2. In the conventional method of lowering, since the elapsed time from the time when the diameter expansion speed is lowered, in other words, the time when the grindstone contact pressure P2 is detected to the end of the machining is long, the grindstone contact pressure P is increased by the time when the machining ends. Whereas the degree of deviation from the contact pressure P2, that is, the variation ΔP, increases, in the method shown in FIG. 1 (a), the grindstone contact pressure P exceeds the final diameter expansion speed V2 before reaching the contact pressure P2. Since the machining of the inner peripheral surface of the workpiece is advanced to some extent at a high diameter expansion speed V1, the elapsed time from the time when the contact pressure P2 is detected to the machining end time can be shortened, and accordingly, at the end of machining. Variation in grinding wheel contact pressure P Is the it is possible to suppress the ΔP.
[0030]
In this embodiment, the diameter expansion speed is switched to two stages. However, the structure may be switched to three or more stages. That is, the final diameter expansion speed may be set to the third or fourth diameter expansion speed for processing which is lower than the second diameter expansion speed for processing. In short, it is sufficient that at least the initial diameter expansion speed, the first diameter expansion speed for processing, and the second diameter expansion speed for processing are included as the diameter expansion speed.
[0031]
Further, the final diameter increasing speed is not limited to a speed that keeps the grindstone contact pressure constant as described above, but is a high speed at which the grindstone contact pressure slightly increases, or the grindstone contact pressure slightly decreases. A lower speed may be set.
[0032]
Further, each diameter expansion speed does not necessarily have to be a fixed speed, and may be corrected each time the workpiece is processed. For example, when the grindstone contact pressure P at the end of machining or the variation rate thereof is out of the allowable range, the diameter expansion speed at the next workpiece machining may be corrected so as to be within the allowable range. .
[0033]
【The invention's effect】
As described above, according to the present invention, before the machining of the inner peripheral surface of the workpiece, the switching of the grinding wheel diameter expansion speed is switched to at least the first machining expansion speed and the second machining expansion speed. Since it is performed over a plurality of stages including switching, there is an effect that the quality can be stabilized by suppressing variations in the grindstone contact pressure at the end of workpiece machining.
[Brief description of the drawings]
FIG. 1A is a graph showing a time change of a grindstone contact pressure in a honing method according to an embodiment of the present invention, and FIG. 1B is a graph showing a time change of a grindstone contact pressure in a conventional honing method. It is a graph.
FIG. 2 is a partial cross-sectional front view of the honing apparatus according to the embodiment of the present invention.
FIG. 3 is a partial sectional front view showing a main part of a grindstone diameter operating means in the honing apparatus.
[Explanation of symbols]
10 Main body shaft 18 Grinding wheel 20 Grinding wheel operating shaft (Wheel diameter operating means)
30 Operation shaft lifting device (grinding wheel diameter operation means)
40 Control device (control means)
54 Load cell (detection means)

Claims

A honing tool in which a plurality of grindstones are arranged in the circumferential direction and mounted so as to be able to protrude and retract in the radial direction, and the grindstone diameter is enlarged so that each grindstone contacts the cylindrical inner peripheral surface of the workpiece. In the honing method for machining the cylindrical inner peripheral surface by reciprocating and rotating in the axial direction,
While detecting the contact pressure between each of the grindstones and the cylindrical inner peripheral surface or a value corresponding thereto,
While expanding the grindstone diameter at a preset initial diameter expansion speed from a state in which each grindstone is spaced inward from the cylindrical inner peripheral surface , the grindstone and the cylindrical inner peripheral surface during the expansion An initial diameter expansion step of comparing the detected value of the contact pressure or a value corresponding thereto with a preset first contact pressure equivalent value ;
When the contact pressure between each of the grindstones and the cylindrical inner peripheral surface or the detected value of the value corresponding thereto reaches a preset first contact pressure equivalent value, the speed of expansion of the grindstone diameter is increased from the initial expansion speed. The cylindrical inner peripheral surface is processed by lowering the first processing diameter expansion speed lower than the radial speed, and the contact pressure between the grindstone and the cylindrical inner peripheral surface during the processing or the equivalent. A first machining step that compares a detected value of the value to be compared with a preset second contact pressure equivalent value that is higher than the first contact pressure equivalent value ;
For processing before danger detection value is pre-Symbol second lower than the first machining diameter speed expansion speed of the grinding wheel diameter from the time it reaches the second contact pressure equivalent value in the first processing step A second machining step of lowering the diameter expansion rate and proceeding the machining of the cylindrical inner peripheral surface,
The honing method is characterized in that the machining is terminated when the diameter of the cylindrical inner peripheral surface reaches a target diameter.

A honing tool in which a plurality of grindstones are arranged in the circumferential direction and mounted so as to be able to appear and retract in the radial direction, and a grindstone diameter operating means for expanding and contracting the grindstone diameter are provided, and each of the grindstones contacts the cylindrical inner peripheral surface of the workpiece. In the state that the honing tool reciprocates in the axial direction with respect to the cylindrical inner peripheral surface and rotates, the honing processing apparatus that processes the cylindrical inner peripheral surface,
Detecting means for detecting a contact pressure between each of the grindstones and the cylindrical inner peripheral surface or a value corresponding thereto;
Control means for controlling the grinding wheel diameter expansion / contraction operation based on the detected value,
The control means expands each grindstone at a preset initial diameter-expanding speed from a state in which each grindstone is spaced inward from the cylindrical inner peripheral surface, and during the diameter expansion, initial diameter operations and for comparing the first contact pressure equivalent value set in advance and the detected value of the contact pressure or a value corresponding thereto of the cylindrical inner peripheral surface, the detection value by the detecting means the first From the time when the contact pressure equivalent value of 1 is reached, the diameter expansion speed of each grindstone is lowered to the first diameter expansion speed for processing lower than the initial diameter expansion speed, and the processing of the cylindrical inner peripheral surface is advanced . During the machining, a contact pressure between each of the grindstones and the cylindrical inner peripheral surface or a detected value corresponding to the contact pressure and a value higher than the first contact pressure equivalent value and a preset second value. a first working diameter operation for comparing the contact pressure equivalent value, to the first working diameter operation Ri said expansion for processing the expanded speed of each grinding wheel the first from the point where the contact pressure or a value corresponding thereto reaches the second contact pressure equivalent value of each grinding wheel and the cylindrical inner peripheral surface A diameter expansion operation including a second diameter expansion operation for advancing the processing of the cylindrical inner peripheral surface by lowering to a second diameter expansion speed for processing that is lower than the diameter speed, A honing apparatus characterized in that the diameter expansion operation is terminated when the diameter of the cylindrical inner peripheral surface reaches a target diameter.