JP4292725B2 - Tightening tool - Google Patents

Description

【数２】

【数３】

【００３２】
そして、下記の（４）式に基づき、速度変動量ｖ[ｋ]からＬ個移動した値を減じて求めた、速度変動量の差である加速度変動量ａ[ｋ]を求めている。かかる加速度変動量ａ[ｋ]は、バンドパスフィルタの役目を果たして、ＰＷＭからのノイズ等の影響を受けることなく、正確な加速度変動を捉えることが出来る。尚、（４）式に示すＬは、例えば、モータが一回転することによって発生する総パルス数、つまり一回転前の値を得られるように決められる（以上、ステップＢ３）。
【数４】

【００３３】
次に、トルク推定部８は、上述のようにして求めた加速度変動量ａ [ｋ]が、任意に定められる閾値を超えたときに、打撃が発生したと推定するようになっており、打撃の発生を推定した場合には（ステップＢ４）、後述する締付判定処理を行うようになっている（ステップＢ５）。尚、本願の発明者らは、マイクによって打撃音を検出することによって、打撃の発生を推定する方法もあるが、モータ１や減速機２の振動音によって打撃を誤推定することがあるので、上述の推定方法による方が望ましいと指摘している。
【００３４】
（本実施形態におけるトルク推定方法）
次に、上述したステップＢ５における締付判定処理を説明するに当たり、まず、締付トルクの推定方法について説明する。その方法の一例として、本願の発明者らは、特願平11-166024号公報において、モータの回転速度と、打撃間のモータの回転量から締付トルクを推定する方法を提案している。この方法は、一打撃毎の運動エネルギーの収支から導き出したものであり、締付で消費されたエネルギーと、ハンマの打撃により出力軸に設けたアンビルに与えられたエネルギーとが略等しいという関係から、締付トルクを推定する方法である。
【００３５】
より具体的には、図４に示すように、出力軸５の回転角θと締付トルクＴが、Ｔ＝τ（θ）の非線形関数で表され、当該非線形関数τを、回転角θで積分した値が、締付で消費されたエネルギーとなる一方、当該出力軸の回転速度ωの２乗の値から、アンビルの慣性モーメントＪ_aを乗じて求めた値の半分の値が、ハンマの打撃によりアンビルに与えられたエネルギーとなるので、かかる２つのエネルギーを等価と置くことで、推定締付トルクを求めることができるのである。
【００３６】
例えば、図４において、ハンマによる打撃が、夫々回転角θ₁、θ₂…、θ_nで発生したとすると、下記の（５）式に示すように、非線形関数τを区間[θ_n、θ_n+1]で積分して求められるエネルギーＥ_nを、打撃間回転角φ_n（＝θ_n+1−θ_n）で除した値が、区間[θ_n、θ_n+1]における平均トルクＴ_naとなる。
【数５】

【００３７】
一方、下記の（６）式に示すように、打撃発生時点θ_nにおける回転速度ω_nの２乗の値から、アンビルの慣性モーメントＪ_aを乗じて求めた値の半分の値が、打撃発生時点θ_nで発生したハンマの打撃によりアンビルに与えられたエネルギーＥ_niとなる。
【数６】

【００３８】
ここで、エネルギーＥ_nとエネルギーＥ_niは等価であるから、（５）式に（６）式を代入して整理し、平均トルクＴ_naを推定締付トルクＴ_nhと呼ぶことにすると、下記の（７）式に示すようになり、この式によって、推定締付トルクＴ_nhを求めることができる（以下、推定締付トルクＴ_hとする）。尚、本願の発明者らは、このようなトルク推定方法以外にも、トルクセンサを用いたり、モータ１の電流量や電圧量、出力軸５の進行角度、ハンマ３の跳ね返り量から推定しても良いと指摘している。
【数７】

【００３９】
（本実施形態のインパクト締付工具における締付判定）
以上のトルク推定方法を念頭に置き、図１及び図５を参照して、上述したステップＢ５における締付判定処理について説明すると、まず、トルク推定部８は、打撃間のカウント数Ｃ_iを読込み、下記の（８）式に従って、そのカウント数Ｃ_iと１カウント当たりの出力軸５の回転角とを乗じて打撃間回転角φ_nを求める。尚、１カウント当たりの出力軸５の回転角は、２πから、出力軸５が１回転する間にトルク推定部８によってカウントされる総カウント数Ｃ_aを除した値となる（ステップＣ１）。
【数８】

【００４０】
また、下記の（９）式に従って、１カウント当たりの出力軸５の回転角２π／Ｃ_aに、平均パルス幅ｗ_aaを除すことによって、打撃発生時点θ_nにおける回転速度ω_nを算出する（ステップＣ２）。
【数９】

【００４１】
そして、（８）式及び（９）式によって、夫々求められた打撃間回転角φ_nと、打撃発生時点θ_nにおける回転速度ω_nとを、上記の（７）式に従って演算することによって、推定締付トルクを求めることができる（ステップＣ３）。次に、トルク推定部８は、推定締付トルクＴ_hを締付判定部９へ出力し、当該締付判定部９は、まず、下記の（１０）式及び（１１）式に従って、夫々、推定締付トルクＴ_h[ｋ]をＭ個及びＮ個移動平均して求めた平均締付トルクＴ_a1、Ｔ_a2を求めて、（３）式に示すように、Ｔ_a1からＴ_a2を減じて求めた平均締付トルクの差からトルク変動量Ｔ_q[ｋ]を求める。
【数１０】

【数１１】

【数１２】

【００４２】
次に、締付判定部９は、（１３）式及び（１４）式に従って、夫々、トルク変動量Ｔ_q[ｋ]をＯ個及びＰ個移動平均して求めた平均トルク変動量Ｔ_qa1、Ｔ_qa2を求めて、（１５）式に示すように、Ｔ_qa1からＴ_qa2を減じて求めた平均トルク変動量の差からトルク変動率Ｔ_v[ｋ]を求める（以上、ステップＣ４）。尚、本願の発明者らは、トルク変動量Ｔ_q又はトルク変動率Ｔ_vを求めるにあたり、単に今回の値と前回の値との差分を取るようにしても良いが、ノイズを考慮すると、やはり移動平均を取った方がよいと指摘している。
【数１３】

【数１４】

【数１５】

【００４３】
ここで、打撃数θ_nに対する推定締付トルクＴ_h、トルク変動量Ｔ_q、トルク変動率Ｔ_vの推移を示す図６も参照して、ステップＣ４以後の処理を説明すると、締付判定部９は、算出したトルク変動率Ｔ_vが、ノイズ等を考慮して任意に定められる判定開始基準値Ａを超え（ステップＣ５）、かつ０以下となった場合には（ステップＣ６）、モータ制御部１０に対して停止指令を出力して、モータ１の回転を停止させるシャットオフ処理を行うようになっており（ステップＣ７）、それ以外の場合には、締付を継続し締付判定処理を終了するようになっている。
【００４４】
このように、トルク変動率Ｔ_vが０となった点は、最大締付トルクＴ_maxのやや手前となり、当該締付完了点で締付動作を停止させることによって、樹脂部材を締付によって破壊することなく、締付を完了することができる。尚、トルク変動量Ｔ_qが０となった点を見てみると、最大締付トルクＴ_maxを超えており、当該部材を破壊してしまうことは言うまでもない。また、本願の発明者らが、判定開始基準値Ａを設けた理由は、締付当初はトルク変動率Ｔ_vが０を示すことと、ノイズ等によっても０となる場合があるので、かかる場合を排除する必要があるためである。
【００４５】
［第２の実施の形態］
（本実施形態における基本思想）
次に、請求項２に記載された手段であるが、本願の発明者らは、第１の実施形態において、樹脂系部材に対し最適な締付を行うことができるインパクト締付工具を提供できたので、次に、どのような締付部材を用いても最適な締付を行うことはできないかと思料し、樹脂系部材にはトルク変動率Ｔ_vが０となったときに締付を停止させる一方、金属系部材にはトルク変動量が０となったときに締付を停止させることを考えた。
【００４６】
そのためには、樹脂系部材であるか金属系部材であるかの判別を行わなくてはならないが、かかる判別の方法として、本願の発明者らは、最大締付トルクＴ_maxが部材によって相違することに着目し、種々の樹脂系部材及び金属系部材の最大締付トルクＴ_maxを調べて、樹脂系部材における複数の最大締付トルクＴ_maxの中で一番大きなものと、金属系部材における複数の最大締付トルクＴ_maxの中で一番小さいものとの境界に、閾値となる部材判定トルクを設け、推定締付トルクＴ_hが当該部材判定トルクを超えるか否かによって、部材の判定を行うことを提案している。
【００４７】
（本実施形態のインパクト締付工具における締付判定）
より具体的には、図７に示す締付判定処理のとおりであって、第１の実施形態と同様にして、トルク推定部８は、打撃間回転角φ_nの算出を行うと共に（ステップＣ１）、打撃発生時点θ_nにおける回転速度ω_nの算出を行って（ステップＣ２）、締付トルクＴの推定を行う（ステップＣ３）。そして、締付判定部９は、ステップＣ３において算出された推定締付トルクＴ_hから、トルク変動量Ｔ_qとトルク変動率Ｔ_vを算出する（ステップＣ４）。
【００４８】
ここで、樹脂系部材を締付ける場合の、打撃数θ_nに対する推定締付トルクＴ_h、トルク変動量Ｔ_q、トルク変動率Ｔ_vの推移を示す図８（ａ）も参照して、ステップＣ４以後の処理を説明すると、本実施形態の締付判定部９は、締付当初は、トルク変動率Ｔ_vで締付判定を行うようになっている（ステップＤ１）。そして、第１の実施形態と同様にして、トルク変動率Ｔ_vが任意に定められる判定開始基準値Ａを超え（ステップＣ５）、かつ０以下となった樹脂系部材の締付完了点θ_rになったときに（ステップＣ６）、推定締付トルクＴ_hが、部材判定トルクＴ₁を超えたかどうか判断し、当該部材判定トルクＴ₁を超えていないので（ステップＤ２）、樹脂系部材の締付を行っていると判断して、シャットオフ処理を行うようになっている（ステップＣ７）。
【００４９】
一方、ステップＤ２において、図８（ｂ）に示すように、当該部材判定トルク値Ｔ₁を超えている場合には、金属系部材の締付を行っていると判断し、樹脂系部材の締付完了点θ_rで締付を停止させると締付不足が生じるので締付を継続すると共に、トルク変動量判定モードに移行し（ステップＤ３）、トルク変動量Ｔ_qが０以下となった金属系部材の締付完了点θ_mになったときに（ステップＤ４）、シャットオフ処理を行うようになっており（ステップＣ７）、トルク変動量Ｔ_qが０以下となっていない場合には、締付を継続し締付判定処理を終了するようになっている。
【００５０】
このように、本実施形態のインパクト締付工具にあっては、締付当初はトルク変動率Ｔ_vを用いて締付判定を行って、樹脂系部材の締付完了点θ_rに達したと判断したときに、推定締付トルクＴ_hが、部材判定トルクＴ₁を超えている場合には、金属系部材を締付けていると判断して締付を継続し、トルク変動量Ｔ_qを用いて締付判定を行って、金属系部材の締付完了点θ_mに達したと判断したときに、シャットオフを行うようになっているので、どのような締付部材を用いても、当該締付部材を破損させることなく、かつ最適な締付状態を得ることができる。
【００５１】
尚、その他の構成及び動作については、第１の実施形態と同様であるので、ここでは特に説明しないこととする。また、以後の各実施形態の説明に際し、同様の処理については、本実施形態の説明に用いた図７のように、同じ符号を付けると共に、枠や矢印を点線で記載して、説明を簡略化又は省略することとする。
【００５２】
［第３の実施の形態］
（本実施形態における基本思想）
次に、請求項３に記載された手段であるが、本願の発明者らは、第２の実施形態において、どのような締付部材でも最適な締付状態を得られるインパクト締付工具を提供できたので、ネジ溝の不揃いや、ボルトとナットの中心軸のずれ等に起因する組立上の不具合によって、図２７に示す締付完了点θ₃まで到達することなく、最初にトルク変動量Ｔ_q（トルク変動率Ｔ_vも該当）が０となったθ₁の点で、締付を停止するという問題に対処できないかと思料していたところ、同図に示すように、当該不具合に起因して一時的に締付トルクＴが上昇する場合のその最大トルクは、締付完了点における締付トルクＴよりも小さいことが極めて多いことに着目した。
【００５３】
そこで、本願の発明者らは、かかる着目点に基づき、一時的に締付トルクＴが上昇する場合のその最大トルクを、種々の不具合毎に調べて、その不具合における複数の最大トルクの中で一番大きなトルクよりも、若干大きなトルクとなるように、閾値となる不具合判定トルクを設け、推定締付トルクＴ_hが当該不具合判定トルクを超えるか否かによって、推定締付トルクＴ_hの上昇が、着座によるものなのか、不具合によるものなのかの判定を行うことを提案している。
【００５４】
（本実施形態のインパクト締付工具における締付判定）
より具体的には、図９に示す締付判定処理のとおりであって、打撃数θ_nに対する推定締付トルクＴ_h等の推移を示す図１０（ａ）も参照して、樹脂系部材を締付ける場合の動作について説明すると、まず、トルク変動率Ｔ_v等を算出して（ステップＣ１〜Ｃ４）、締付当初は、トルク変動率Ｔ_vで締付判定を行い（ステップＤ１）、打撃数がθ₁となったときに、トルク変動率Ｔ_vが既に判定開始基準値Ａを超え（ステップＣ５）、かつ０以下となったので（ステップＣ６）、推定締付トルクＴ_hが、部材判定トルクＴ₁を超えたかどうか判断し、当該部材判定トルクＴ₁を超えていないので（ステップＤ２）、樹脂系部材を締付けていると判断する。
【００５５】
このとき、本実施形態の締付判定部９は、推定締付トルクＴ_hが、不具合判定トルクＴ₂を超えているか否かを判断し、当該不具合判定トルクＴ₂を超えていないので（ステップＥ１）、何らかの不具合が発生していると判断し、トルク変動率Ｔ_vのクリアを行い（ステップＥ２）、締付を継続して、締付判定処理を終了するようになっている。尚、打撃数がθ₂となったときには、トルク変動率Ｔ_vが０以下となっているが、判定開始基準値Ａを超えていないので（ステップＣ５）、同様に締付を継続して、締付判定処理を終了するようになっている。
【００５６】
一方、打撃数がθ_rとなった場合は、トルク変動率Ｔ_vが既に判定開始基準値Ａを超え（ステップＣ５）、かつ０以下となったので（ステップＣ６）、再び推定締付トルクＴ_hが、部材判定トルクＴ₁を超えたかどうか判断し、当該部材判定トルクＴ₁を超えていないので（ステップＤ２）、樹脂系部材を締付けていると判断する。次に、推定締付トルクＴ_hが、不具合判定トルクＴ₂を超えているか否かを判断し、当該不具合判定トルクＴ₂を超えているので（ステップＥ１）、不具合は発生せずに、締付部材が適性に締付けられている（着座している）と判断して、シャットオフ処理を行うようになっている（ステップＣ７）。
【００５７】
尚、図１０（ｂ）に示す金属系部材を締付ける場合には、樹脂系部材の締付完了点θ_rとなったときに、推定締付トルクＴ_hが、部材判定トルクＴ₁を超えるので（ステップＤ２）、トルク変動量判定モードに移行し（ステップＤ３）、トルク変動量Ｔ_qが０以下となる金属系部材の締付完了点θ_mになったときに（ステップＤ４）、推定締付トルクＴ_hが、不具合判定トルクＴ₂を超えているか否かを判断し、当該不具合判定トルクＴ₂を超えたときに（ステップＥ１）、シャットオフ処理を行うようになっている（ステップＣ７）。
【００５８】
このように、本実施形態のインパクト締付工具にあっては、トルク変動率Ｔ_v又はトルク変動量Ｔ_qが０以下となったときの推定締付トルクＴ_hが、不具合判定トルクＴ₂を超えたときに、シャットオフを行うようになっているので、組立上の若干の不具合があっても、最適な締付を行うことができるのである。尚、その他の構成及び動作については、上述の各実施形態と同様であるので、ここでは特に説明しないこととする。
【００５９】
［参考例１］
（本実施形態における基本思想）
本願の発明者らは、上記の第３の実施形態において、不具合判定トルクＴ2を採用することで、組立上の若干の不具合があっても、最適な締付を行うことができるインパクト締付工具を提供することができたが、当該不具合判定トルクＴ2は不変であるため、締付完了点θr、θmにおける推定締付トルクＴhが、当該不具合判定トルクＴ2よりも小さくなる設計範囲外の締付部材を締付る場合には、締付が完了しているにも係らず、締付動作がなお継続されてしまう恐れがあった。
【００６０】
一方、締付完了点θr、θm以前で、トルク変動率Ｔv等が０となったときの推定締付トルクＴhが、当該不具合判定トルクＴ2よりも大きくなる設計範囲外の締付部材を締付る場合や、過大なノイズが加わって、当該不具合判定トルクＴ2よりも大きくなった場合には、締付が完了していないにも係らず、締付動作を停止してしまう恐れがあった。そこで、本願の発明者らは、かかる問題点を解決すべく、不具合判定トルクＴ2を変更できる手段を提案している。
【００６１】
（本実施形態のインパクト締付工具の構成）
そのための具体的なインパクト締付工具の構成は、図１１に示すとおりであって、図１に示した従来のインパクト締付工具の構成に対して、締付判定部９と接続され、不具合判定トルクＴ₂を変更することができる、不具合判定トルク設定器１４ａを設けたものである。この不具合判定トルク設定器１４ａは、例えば可変抵抗器等を用いて、不具合判定トルクＴ₂を自在に設定できるようにすれば良い。
【００６２】
このように、当該設定器１４ａを設けることによって、作業者が作業現場において、対象とする脆い締付部材又は頑丈な部材に応じて、夫々当該不具合判定トルクＴ₂の設定を行うことができるので、上述した不停止や途中停止を回避し、最適な締付状態を得ることができる。尚、その他の構成及び動作については、上述の各実施形態と同様であるので、ここでは特に説明しないこととする。
【００６３】
［参考例２］
（本実施形態における基本思想）
本願の発明者らは、上記の参考例１において、不具合判定トルク設定器１４ａを設けることで、設計範囲外の締付部材を締付る場合や、過大なノイズが加わっても、上述した不停止や途中停止を回避することができたが、締付完了時の締付トルクが小さい部材と大きい部材とを混合して締付作業を行う場合、夫々の部材に合わせて、不具合判定トルクＴ2を設定する必要があるため、作業効率の低下をもたらす恐れがあった。
【００６４】
これに対し、本願の発明者らは、かかる問題点に対処できる糸口はないかと、試行錯誤を繰り返していたところ、図１０に示すように、不具合に起因して一時的に締付トルクＴが上昇する場合のその最大値は、締付完了時における締付部材の締付トルクの大きさに比例することが多く、また、当該最大値は一番初めに計測される締付トルク（推定締付トルクＴ_h）が一番大きいことが多いということに着目し、始動から任意の回転数までの推定締付トルクＴ_hの推移から最大トルクを求めて、その最大トルクに応じて不具合判定トルクＴ₂を設定することで、上述の問題点を解決できることに気が付いた。
【００６５】
そこで、本願の発明者らは、かかる解決方法を具現化すべく、締付の対象とする全締付部材の締付が完了するまでの所要回数を調べ、その中で最も所要回転数の少ない部材の当該回転数を、判定回転数とし、始動からその判定回転数を回転したときまでの推定締付トルクＴhの中で最大トルクを求め、当該最大トルクに微小値を加えた値を、不具合判定トルクＴ2とする手段を提案している。
【００６６】
（本実施形態における不具合判定トルクＴ₂の設定について）
その手段を実現するためのインパクト締付工具の構成は、図１２に示すように、図１に示した従来のインパクト締付工具の構成に対して、トルク推定部８及び締付判定部９と接続された不具合判定トルク自動設定部１５を設けたものである。そして、その動作は、図１３に示す締付判定処理のとおりであって、まず、トルク推定部８から打撃間回転角φ_nが入力されると（ステップＣ１）、下記の（１６）式に基づいて、始動されてから現在までの出力軸５の総回転数ψ_allを求めるようになっている（ステップＦ１）。
【数１６】

【００６７】
次に、打撃数θ_nに対する推定締付トルクＴ_h等の推移を示す図１４も参照して、当該自動設定部１５の動作の説明を続けると、総回転数ψ_allが判定回転数ψ_h以上となったかどうか判断して（ステップＦ２）、その回転数ψ_hを超えていない場合には、それまでに算出した推定締付トルクＴ_hの中で最大のトルクに、任意の微小トルクＴ_gを加えた値を不具合判定トルクＴ₂とする一方（ステップＦ３）、判定回転数ψ_hを超えた場合には、始動後ψ_h回転までにおける推定締付トルクＴ_hの中で最大のトルクＴ_m1に、任意の微小トルクＴ_gを加えた値を不具合判定トルクＴ₂とするようになっている（ステップＦ４）。
【００６８】
このようにすることで、締付完了時の締付トルクが小さい部材と、締付トルクが大きい部材とを混合して締付作業を行う場合であっても、夫々の部材に合わせて、不具合判定トルクを設定する必要がないため、作業効率を改善しせしめることができる。尚、最大のトルクＴ_m1に微小トルクＴ_gを加えるのは、当該トルクを加えないと、容易に不具合判定トルクＴ₂を超える恐れがあるためである。また、ステップＦ３及びＦ４以降の処理は、第３の実施形態で用いた図９のステップＣ２〜Ｃ７の処理と同様であると共に、その他の構成及び動作についても、上述の各実施形態と同様であるので、ここでは特に説明しないこととする。
【００６９】
［参考例３］
（本実施形態における基本思想）
本願の発明者らは、上記の参考例２において、始動から判定回転数ψhを回転したときまでの中で最大トルクＴm1を求め、当該最大トルクＴm1に一定値Ｔgを加えた値を、不具合判定トルクＴ2とすることで、締付完了時の締付トルクが小さい部材と大きい部材とを混合して締付作業を行う場合であっても、適切な締付状態を得ることに成功した。
【００７０】
しかしながら、始動直後の推定締付トルクＴ_hが、何らかの外乱によって過小であったり、またはその逆で過大であった場合には、その推定締付トルクの大きさに合わせて、不具合判定トルクＴ₂が過小又は過大に設定されてしまうため、締付完了点まで到達することなく、締付を停止してしまったり、締付動作が継続されてしまう恐れがあった。そこで、本願の発明者らは、かかる問題点を解決すべく、不具合判定トルクＴ₂が過小又は過大にならないように、所定の上限と下限を与えることを提案している。
【００７１】
（本実施形態における不具合判定トルクＴ₂の設定について）
より具体的には、図１５に示す締付判定処理のとおりであって、トルク推定部８から打撃間回転角φ_nが入力されると（ステップＣ１）、始動されてから現在までの出力軸５の総回転数ψ_allを求め（ステップＦ１）、総回転数ψ_allが判定回転数ψ_h以上となったかどうか判断する（ステップＦ２）。そして、本実施形態の不具合判定トルク自動設定部１５は、当該決定回転数ψ_hを超えていない場合には、不具合判定トルクＴ₂を、初期設定トルクＴ_dのままとし、当該判定トルクＴ₂の変更は行わない（ステップＧ１）。
【００７２】
次に、当該決定回転数ψ_hを超えた場合について、打撃数θ_nに対する推定締付トルクＴ_h等の推移を示す図１６（ａ）も参照して、当該自動設定部１５の動作の説明を続けると、始動後ψ_h回転までにおける推定締付トルクＴ_hの中で最大のトルクＴ_m1に、任意の微小トルクＴ_gを加えた値を不具合判定トルクＴ₂の仮設定値Ｔ_2Pとし（ステップＦ４ａ）、その仮設定値Ｔ_2Pが、初期設定トルクＴ_d以上の場合には（ステップＧ２）、判定値が大き過ぎると判断して、初期設定トルクＴ_dを不具合判定トルクＴ₂とする（ステップＧ３）。
【００７３】
一方、図１６（ｂ）に示すように、ステップＧ２において、仮設定値Ｔ_2Pが、初期設定トルクＴ_d以下であり、かつ予め任意に定められた許容下限トルクＴ_L以下の場合には（ステップＧ４）、判定値が小さ過ぎると判断して、許容下限トルクＴ_Lを不具合判定トルクＴ₂とする（ステップＧ５）。ところで、ステップＧ４において、仮設定値Ｔ_2Pが、許容下限トルクＴ_L以上となる場合には、判定値が適性値であると判断して、仮設定値Ｔ_2Pを不具合判定トルクＴ₂とするようなっている（ステップＧ６）。
【００７４】
このようにすることで、始動直後の推定締付トルクＴ_hが、何らかの外乱によって過小であったり、またはその逆で過大であった場合であっても、適性な締付完了点に到達することなく締付を停止してしまったり、締付動作が継続されてしまう恐れがなく、最適な締付状態を得ることができる。尚、ステップＧ１、Ｇ５、Ｇ６以降の処理は、第３の実施形態で用いた図９のステップＣ２〜Ｃ７の処理と同様であると共に、その他の構成及び動作についても、上述の各実施形態と同様であるので、ここでは特に説明しないこととする。
【００７５】
［参考例４］
（本実施形態における基本思想）
本願の発明者らは、上述の参考例２及び参考例３において、判定回転数ψhを導入し、締付完了時の締付トルクが小さい部材と大きい部材とを混合して締付作業を行う場合であっても、適切な締付状態を得ることに成功したが、かかる判定回転数ψhを採用することで、本願の発明者らが意図した効果とは、別の効果も持っていることに気が付いた。それは、第３の実施形態において採用した不具合判定トルクＴ2を用いなくても、当該回転数に達していない間は、トルク変動率Ｔv等が０になっても締付を継続する手段を用いることで、適切な締付を得ることができるというものである。
【００７６】
（本実施形態のインパクト締付工具における締付判定）
より具体的には、図１７に示す締付判定処理のとおりであって、第３の実施形態を示した図９のフローチャートにおいて、ステップＥ１及びＥ２の代わりに、総回転数ψ_allが判定回転数ψ_hを超えたかどうかを判断するステップＨを採用し、当該回転数ψ_hを超えたかどうかによって、ボルトとナットの中心軸のずれ等に起因する組立上の不具合が発生したか否かを判断している。
【００７７】
さらに詳しく、打撃数θ_nに対する推定締付トルクＴ_h等の推移を示す図１８も参照して、本実施形態の動作について説明すると、トルク変動率Ｔ_vが０以下となった樹脂系部材の締付完了と判断されるθ₁、θ₂の点において（ステップＣ６）、総回転数ψ_allが判定回転数ψ_hを超えたかどうかをみると、両点とも当該回転数ψ_hを超えていないので（ステップＨ）、何らかの不具合が発生していると判断し、締付を継続して、締付判定処理を終了するようになっている。
【００７８】
一方、同じくトルク変動率Ｔ_vが０以下となったθ_r及び、トルク変動量Ｔ_qが０以下となった金属系部材の締付完了と判断されるθ_mの点において、総回転数ψ_allが判定回転数ψ_hを超えたかどうかをみると、両点とも当該回転数ψ_hを超えているので（ステップＨ）、不具合は発生せずに、締付部材が適性に締付けられている（着座している）と判断して、シャットオフ処理を行うようになっている（ステップＣ７）。
【００７９】
尚、本実施形態の説明で用いている図１８は、金属系部材の締付の例を示しており、樹脂系部材の締付完了点θ_rにおける推定締付トルクＴ_hが、部材判定トルクＴ₁以上となっているので（ステップＤ２）、金属系部材を締付けていると判断され、変動量モードへ移行し（ステップＤ３）、金属系部材の締付完了点θ_mになったときに（ステップＤ４）、シャットオフ処理を行うようになっていることは（ステップＣ７）、第２の実施形態で説明したとおりである。
【００８０】
このように、締付完了と判断された時点において、総回転数ψ_allが判定回転数ψ_hを超えているか否かを判断し、当該判定回転数ψ_hを超えたときに、シャットオフすることで、組立上の若干の不具合があっても、最適な締付を行うことができるのである。尚、その他の構成及び動作については、第３の実施形態と同様であるので、ここでは特に説明しないこととする。
【００８１】
［参考例５］
（本実施形態における基本思想）
本願の発明者らは、上記の参考例４において、判定回転数ψhを採用することで、組立上の若干の不具合があっても、最適な締付を行うことができるという別の効果を見出したが、当該判定回転数ψhは不変であるため、判定回転数ψhよりも少ない回転数で締付が完了する設計範囲外の締付部材を締付る場合には、締付が完了しているにも係らず、締付動作がなお継続されてしまう恐れがあった。
【００８２】
一方、締付までの所要回数が極端に少ない部材と、締付までの所要回数が非常に多い部材とを混合して締付ける場合、上述のように、締付動作が継続されてしまうことを防ぐため、判定回転数ψhは締付までの所要回数が極端に少ない部材に合わせて設定されるが、そうすると、締付までの所要回数が非常に多い部材のその回転数からみると、判定回転数ψhは非常に小さい回転数となるため、両回転数間で組立上の若干の不具合に起因する推定締付トルクＴhの上昇があった場 合には、締付が完了していないにも係らず、締付動作を停止してしまう恐れがあった。そこで、本願の発明者らは、かかる問題点を解決すべく、判定回転数ψhを変更できる手段を提案している。
【００８３】
（本実施形態のインパクト締付工具の構成）
そのための具体的なインパクト締付工具の構成は、図１９に示すとおりであって、図１に示した従来のインパクト締付工具の構成に対して、締付判定部９と接続され、判定回転数ψhを変更することができる判定回転数設定器１４ｂを設けたものである。この判定回転数設定器１４ｂは、参考例１に示した不具合判定トルク設定器１４ａと同様にして、例えば可変抵抗器等を用いて、判定回転数ψhを自在に設定できるようにすれば良い。
【００８４】
このように、当該設定器１４ｂを設けることによって、作業者が作業現場において、対象とする回転数の少ない締付部材又は、回転数の多い部材の夫々に応じて、当該判定回転数ψ_hの設定を行うことができるので、上述した不停止や途中停止を回避し、最適な締付状態を得ることができる。尚、その他の構成及び動作については、上述の各実施形態と同様であるので、ここでは特に説明しないこととする。
【００８５】
［参考例６］
（本実施形態における基本思想）
本願の発明者らは、上述の各実施形態において、あらゆる締付部材を用いたり、組立上の若干の不具合があったりしても、当該締付部材を破損させることなく、最適な締付を行うことができる締付工具を提供することができたが、本願の発明者らの創作意欲はそこに留まることなく、既に締付されている締付部材に対して、誤って締付が行われた場合について対処できないかと思料し、既に締付されている締付部材を締付けた場合には、初めから推定締付トルクＴhの値が大きな値となって現れることを利用しようと考えた。
【００８６】
そこで、本願の発明者らは、かかる現象を利用しようと、再び最大締付トルクＴmaxが部材によって相違することに着目し、種々の樹脂系部材の最大締付トルクＴmaxを調べて、樹脂系部材における複数の最大締付トルクＴmaxの中で一番小さいトルクを、増し締め判定トルクとし、推定締付トルクＴhが当該増し締め判定トルクを超えるか否かによって、既に締付されている締付部材に対して、誤って締付が行われたか否かを判断する手段を提案している。
【００８７】
（本実施形態のインパクト締付工具における増し締め判定）
より具体的には、図２０に示す締付判定処理のとおりであって、第３の実施形態を示した図９のフローチャートにおけるステップＣ５において、トルク変動率Ｔ_vが判定開始基準値Ａを超えていないと判断されたとき、すなわち、ＮＯのときに、推定締付トルクＴ_hが増し締め判定トルクＴ₃を超えるかを判断するステップＪを設け、当該ステップＪにおいて、増し締め判定トルクＴ₃を超えているか否か判断し、その判定トルクＴ₃を超えている場合には、シャットオフするようにしている（ステップＣ７）。
【００８８】
さらに詳しく、打撃数θ_nに対する推定締付トルクＴ_h等の推移を示す図２１も参照して、本実施形態の動作について説明すると、増し締めが行われたときのトルク変動率Ｔ_v等の変化は極めて少なく、判定開始基準値Ａを超えることはない（ステップＣ５）。しかしながら、この場合であっても、図１０のθ₂に示すように、単に判定開始基準値Ａを超えていないだけの場合があるので、推定締付トルクＴ_hが増し締め判定トルクＴ₃を超えているかどうか判断して、図２１に示すように、当該判定トルクＴ₃を超えている場合には（ステップＪ）、増し締めが行われたとしてシャットオフを行う（ステップＣ７）。
【００８９】
一方、当該判定トルクＴ₃を超えていない場合には（ステップＪ）、上述の図１０におけるθ₂のように、増し締めがされているのではなく、適性な締付作業が行われていると判断して、締付動作を継続するようになっている。このように、トルク変動率Ｔ_v等が判定開始基準値Ａを超えることなく、かつ、推定締付トルクＴ_hが増し締め判定トルクＴ₃を超えたときに、増し締めが発生したと判断して、シャットオフすることによって、無駄な作業を行わずに済むと共に、増し締めによって消費されるエネルギーをも削減することができるのである。
【００９０】
尚、本実施形態における判定開始基準値Ａは、増し締めが行われたときに、トルク変動率Ｔ_v等が当該基準値Ａを超えることがないように定められる。また、本実施形態にあっては、第３の実施形態を基本として説明したため、樹脂系部材における複数の最大締付トルクＴ_maxの中で一番小さいトルクを、増し締め判定トルクとしているが、金属系部材のみを締付けるような場合にあっては、金属系部材における複数の最大締付トルクＴ_maxの中で一番小さいトルクを採用することは言うまでもない。
【００９１】
［参考例７］
（本実施形態における基本思想）
本願の発明者らは、上記の参考例６において、無駄な作業を行わずに済むインパクト締付工具を提供することができたが、作業効率のさらなる向上を目指し、以上の各実施形態において、誤判定により途中停止した場合には、締付作業を継続するために作業者がトリガを引き直す必要が生じ、面倒であるということに着目した。そこで、本願の発明者らは、かかる事態を改善すべく、トリガが解放されずに一定時間を経過した場合には、再びインパクト締付工具の回転制御を行う手段を提案している。
【００９２】
（本実施形態のインパクト締付工具における定常処理）
より具体的には、図２２に示す締付判定処理のとおりであって、第１の実施形態を示した図２のフローチャートにおけるステップＡ５が処理された後に、タイマ計測を開始し（ステップＩ１）、トリガが解放されず（ステップＡ６）、所定時間Ｔ_mが経過したときに（ステップＩ２）、再びモータ１の回転制御を行うようにしたものである（ステップＡ２）。このようにすることで、上述の各実施形態において、誤判定により途中停止した場合であっても、所定時間Ｔ_mが経過したときに自動的に回転制御を始めるので、作業者は態々トリガを引きなおす必要がなく、作業性を向上せしめることができる。
【００９３】
[各実施形態における補足事項について]
以上の各実施形態にあっては、インパクト締付工具を用いて説明したが、本願の発明者らは、かかる方式の締付工具に限定されるものではなく、広く一般の締付工具にも採用することができると共に、回転速度検出手段として周波数ジェネレータを用い、パルスエッジをカウントすることで、回転角検出手段として代用しているが、かかるものに限定するものではなく、エンコーダやポテンショメータによって代替しても良いと指摘している。尚、エンコーダ等で回転速度を求めるには、差分をとることによって求めるのが一般的である。
【００９４】
また、第１の実施形態において説明したように、本願の発明者らは、トルク変動率Ｔ_q及びトルク変動率Ｔ_vを、移動平均の差分によって求めているが、ノイズを考慮したためであって、単に今回の値と前回の値との差分を取るようにしても良いし、回転角θによる微分値のみならず、時間による微分値であっても良いと主張している。すなわち、本願の発明者らの主張を、より具体的に表すと、トルク変動量Ｔ_qは、（１７）式に示すように、回転角θ又は時間ｔの変化に対する締付トルクＴの変化の割合を意味するものである。
【数１７】

【００９５】
一方、トルク変動率Ｔ_vは、（１８）式に示すように、回転角θ又は時間ｔの変化に対するトルク変動量Ｔ_qの変化の割合を意味するものである。
【数１８】

【００９６】
さらに、本願の発明者らは、上述の各実施形態にあっては、トルク変動量Ｔ_q、トルク変動率Ｔ_vが所定の閾値を超えて、０以下となったときに締付の判定を行っているが、所定の閾値以下となったときに、締付と判定するようにしても良いと主張していると共に、当該トルク変動量Ｔ_q等が所定の閾値を超える代わりに、又はその条件と共に、当該トルク変動量Ｔ_q等が正の値を継続間の、当該トルク変動量Ｔ_q等の和を求め、その和が閾値を超えた時点を締付完了点と判定する方法でも良いと指摘している。
【発明の効果】
【００９７】
以上のように、請求項１記載の発明にあっては、トルク変動率が判定開始基準値を超えた後、約０以下となったときに、ネジ等の締付が完了したと判断し、モータを停止させるようにしているので、樹脂部材等の脆性材料を締付によって破壊することなく、適性な締付をすることができるという効果を奏する。
【００９８】
次に、請求項２記載の発明にあっては、トルク変動率が判定開始基準値を超えた後、約０以下となったときに、締付トルクが部材判定トルクを超えるかどうか判断し、その部材判定トルクを超えていない場合には、樹脂系部材の締付が完了したと判断する一方、前記部材判定トルクを超えている場合には、モータの回転制御を継続し、トルク変動量が約０以下となったときに、金属系部材の締付が完了したと判断し、モータを停止させるようにしているので、どのような締付部材を用いても、当該締付部材を破損させることなく、かつ最適な締付状態を得ることができるという効果を奏する。
【００９９】
次に、請求項３記載の発明にあっては、締付が完了したと判断したときに、締付トルクが不具合判定トルクを超えるかどうか判断し、その不具合判定トルクを超えていない場合には、不具合等が発生していると判断して、モータの回転制御を継続する一方、前記不具合判定トルクを超えた場合には、ネジ等が適性に締付けられていると判断して、モータを停止させるようにしているので、組立上の不具合があっても、最適な締付を行うことができるという効果を奏する。
【図面の簡単な説明】
【図１】 本願におけるインパクト締付工具の基本的な構成図である。
【図２】 インパクト締付工具の定常処理を示すフローチャートである。
【図３】 本願におけるインパクト締付工具の打撃検出処理を示すフローチャートである。
【図４】 回転角θに対する締付トルクＴの関係を示す図である。
【図５】 第１の実施形態におけるインパクト締付工具の締付判定処理を示すフローチャートである。
【図６】 第１の実施形態におけるインパクト締付工具の応答を示す図であって、打撃数θnに対する推定締付トルクＴh、トルク変動量Ｔq、トルク変動率Ｔvの推移を示している。
【図７】 第２の実施形態におけるインパクト締付工具の締付判定処理を示すフローチャートである。
【図８】 第２の実施形態におけるインパクト締付工具の応答を示した図であって、打撃数θnに対する推定締付トルクＴh、トルク変動量Ｔq、トルク変動率Ｔvの推移を示しており、（ａ）は樹脂系部材を締付けた場合の図、（ｂ）は金属系部材を締付けた場合の図である。
【図９】 第３の実施形態におけるインパクト締付工具の締付判定処理を示すフローチャートである。
【図１０】 第３の実施形態におけるインパクト締付工具の応答を示した図であって、打撃数θnに対する推定締付トルクＴh、トルク変動量Ｔq、トルク変動率Ｔvの推移を 示しており、（ａ）は樹脂系部材を締付けた場合の図、（ｂ）は金属系部材を締付けた場合の図である。
【図１１】 参考例１におけるインパクト締付工具の構成図である。
【図１２】 参考例２におけるインパクト締付工具の構成図である。
【図１３】 参考例２におけるインパクト締付工具の締付判定処理を示すフローチャートである。
【図１４】 参考例２におけるインパクト締付工具の応答を示した図であって、打撃数θnに対する推定締付トルクＴh、トルク変動量Ｔq、トルク変動率Ｔvの推移を示している。
【図１５】 参考例３におけるインパクト締付工具の締付判定処理を示すフローチャートである。
【図１６】 参考例３におけるインパクト締付工具の応答を示した図であって、打撃数θnに対する推定締付トルクＴh、トルク変動量Ｔq、トルク変動率Ｔvの推移を示しており、（ａ）は仮設定値Ｔ2Pが初期設定トルクＴd以上の場合の図、（ｂ）は仮設定値Ｔ2Pが許容下限トルクＴL以下の場合の図である。
【図１７】 参考例４におけるインパクト締付工具の締付判定処理を示すフローチャートである。
【図１８】 参考例４におけるインパクト締付工具の応答を示した図であって、打撃数θnに対する推定締付トルクＴh、トルク変動量Ｔq、トルク変動率Ｔvの推移を示している。
【図１９】 参考例５におけるインパクト締付工具の構成図である。
【図２０】 参考例６におけるインパクト締付工具の締付判定処理を示すフローチャートである。
【図２１】 参考例６におけるインパクト締付工具の応答を示した図であって、打撃数θnに対する推定締付トルクＴh、トルク変動量Ｔq、トルク変動率Ｔvの推移を示している。
【図２２】 参考例７に係るインパクト締付工具の定常処理を示すフローチャートである。
【図２３】 従来の実施形態におけるインパクト締付工具の構成図である。
【図２４】 締付作業における打撃数θnに対する、締付トルクＴとトルク変動量Ｔqの変化を示す図である。
【図２５】 従来の締付判定処理を示すための図であって、回転角θに対する、締付トルクＴとトルク変動量Ｔqの変化を示している。
【図２６】 従来の締付判定処理を用いて樹脂系部材を締め付け、トルク変動量Ｔqが０となったところで、締付が完了したと判断した場合の図である。
【図２７】 ネジ溝が不揃いであったり、ボルトとナットとの間に挟持した部材が微妙に湾曲をしていたり、ボルトとナットの中心軸のずれ、塵の捲き込みや、ネジ穴の表面にある焼付塗装の削り取り等によって、一時的に締付トルクＴが上昇する場合を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tightening tool used for tightening work such as screws and bolts, such as a drill driver and a wrench.
[0002]
[Prior art]
[Configuration of impact tightening tool]
Conventionally, for tightening screws and bolts at construction sites and assembly factories, etc., a tightening tool that can be quickly tightened using the rotational force of the motor to improve workability. In recent years, among the tightening tools, aiming to further improve workability, convert the rotation of the motor into hammering and perform tightening work with its strong impact force. As a result, impact tightening tools capable of obtaining a higher torque than a rotary tool using only a speed reducer are becoming popular.
[0003]
FIG. 23 is a block diagram showing the configuration of the impact tightening tool. As shown in the vicinity of the center of the drawing, the motor 1 is a driving means and a transmission mechanism that reduces the rotation of the motor 1 at a predetermined reduction ratio. The reduction gear 2, the hammer 3 through which the rotation of the motor 1 is transmitted through the reduction gear 2, the anvil 4 struck by the hammer 3, and the output that transmits the impact force generated by the impact to screws, bolts, etc. A shaft 5 is provided, and the hitting by the anvil 4 occurs when a force of a predetermined value or more is applied between the hammer 3 and the anvil 4 and the hammer 3 rotates with respect to the anvil 4 more than a certain value. Yes.
[0004]
In addition, the tightening tool generates a frequency signal proportional to the number of rotations of the motor 1. The frequency generator 6 serves as a rotational speed detection means for the output shaft 5, and the frequency signal generated by the frequency generator 6 is subjected to waveform shaping. Then, a waveform shaping circuit 7 that outputs a pulse signal having a pulse width corresponding to the rotation speed of the output shaft 5 and a calculation process based on the pulse signal estimate how much tightening torque has been generated. The torque estimation unit 8 and a limit torque setting unit 14c for setting a desired tightening torque are provided, and the set torque set by the limit torque setting unit 14c and the estimated tightening obtained by the torque estimation unit 8 A tightening determination unit 9 a that compares the torque with the torque and outputs a control command to the motor 1 is provided.
[0005]
More specifically, the tightening determination unit 9a issues a stop command to stop the motor 1 via the motor control unit 10 and the motor control circuit 11 when the estimated tightening torque exceeds the set torque. When the motor control unit 10 has not received a stop command from the tightening determination unit 9a, the motor control unit 10 issues a rotation command or a stop command to the motor control circuit 11 in response to the pulling of the trigger 12. While outputting and rotating or stopping the motor 1, when a stop command is received, the motor 1 is not rotated until the trigger 12 is once released.
[0006]
The motor control circuit 11 includes, for example, a pulse width modulation control (PWM control) circuit and the like. The motor control circuit 11 receives power supply from the rechargeable battery 13 such as nickel-cadmium or nickel-hydrogen, and the motor control unit 10. The motor 1 is controlled in accordance with a control command from.
[0007]
[Problems of conventional impact tightening tools]
However, since the impact tightening tool described above must determine the target set torque by the limit torque setter 14c, when performing tightening of a plurality of members having the same proper tightening torque, The work can be continued as it is without changing the set torque, but when multiple members with different proper tightening torques are tightened, the operator must It was necessary to change the set torque each time, which caused a reduction in work efficiency. In addition, if the set torque is selected incorrectly, there is a problem in that tightening is insufficient or the tightening member is damaged.
[0008]
Therefore, the inventors of the present application have determined that the number of hits θ in the lower part of FIG. _n -As shown in the tightening torque T characteristic, an attempt is made to use a response specific to a tightening operation in which a tightening member such as a screw comes into contact with a tightened member and the increase in the tightening torque T reaches a peak. Thought. More specifically, when a tightening member such as a screw starts to come into contact with the member to be tightened, the tightening torque T increases, and accordingly, the number of impacts θ in the upper stage of FIG. _n -Torque fluctuation amount T _q The characteristic suddenly rises and settles to a constant value, but when the tightening of the tightening member and the tightened member is completed and the tightening member stops rotating, it tries to use a response that suddenly drops to zero. I thought.
[0009]
[Conventional technology using torque fluctuation]
This torque fluctuation amount T _q For example, Japanese Patent Application Laid-Open No. 61-8284 discloses a “bolt tightening method” as shown in FIG. (K) is obtained, and the difference G (K) between the average value S (K) and the previous average value S (K-1) is obtained, and the difference G (K) is decreased from the threshold value MS. A method is disclosed in which the tightening of the bolt is stopped.
[0010]
By the way, considering the fact that the tightening is firmly completed, the torque fluctuation amount T is not stopped when the bolt tightening is stopped when the value is lower than the threshold value MS as in the related art. _q It should be better to stop tightening when becomes zero. Nevertheless, the background to which the conventional technique adopts the threshold value MS is that the fastening member and the member to be fastened may be a strong member made of a metal material or the like, but the resin material or the like Thus, it is assumed that the case where a brittle member that may be damaged when excessive tightening torque is applied is also taken into consideration.
[0011]
[Problems to be solved by the invention]
Therefore, in the related art, if the threshold value MS is set high in consideration of tightening the resin-based member, unlike the resin-based member that only needs to be engaged, it is robust. Insufficient tightening may occur in the tightening of metal members that are required to be tightened. However, in consideration of tightening the metal member, when the resin member is tightened with the threshold value MS set to 0, that is, the torque fluctuation amount T _q When the tightening of the resin-based member is stopped when the value becomes 0, as shown in the center of FIG. 26, the resin member is stopped at a point past the maximum point of the tightening torque T. There was a problem of damaging the system members.
[0012]
The responses shown in FIGS. 24 to 26 are very ideal. Actually, the thread groove is not uniform, or the member sandwiched between the bolt and the nut is slightly curved. As shown in FIG. 27, the tightening torque T may temporarily increase due to deviation of the central axis of the bolt and nut, dusting, scraping of the baking paint on the surface of the screw hole, and the like. Nevertheless, in the above-described prior art, the torque fluctuation amount T _q When the difference G (K) corresponding to is reduced below the threshold value MS, the bolt tightening is stopped. _Three First, the torque fluctuation amount T is reached without reaching the point _q Becomes 0 ₁ In this point, the fastening is stopped, and there is a problem that the fastening is finished in an incomplete state.
[0013]
The present invention has been made in view of such problems, and the object of the present invention is to use any tightening member, even if there is a slight problem in assembly. An object of the present invention is to provide a tightening tool capable of performing optimal tightening without damaging a member.
[0014]
[Means for Solving the Problems]
In view of this, the inventors of the present application first considered performing optimal tightening on the resin-based member, and when the torque fluctuation rate, which is a change in the torque fluctuation amount, becomes zero instead of the torque fluctuation amount. It has been found that an optimum tightening state can be obtained without damaging the resin-based member by stopping the tightening. The means for tightening the resin-based member using the torque fluctuation rate is the means described in claim 1,
Motor control means for controlling rotation and stop of the motor, and torque estimation means for estimating the tightening torque of the output shaft of the motor, and tightening screws and bolts using the rotational force of the motor A tightening tool for performing work, wherein a torque fluctuation amount as a ratio of a change in the tightening torque with respect to a change in the rotation angle or time of the motor is obtained, and the torque fluctuation amount with respect to a change in the rotation angle or time of the motor The torque fluctuation rate, which is the rate of change of the torque, is obtained, and when the torque fluctuation rate exceeds about a predetermined determination start reference value and then becomes approximately 0 or less, it is determined that the tightening of the screw or the like has been completed. In addition, the motor control means includes a tightening determination means for outputting a stop command.
[0015]
Next, the inventors of the present application considered to perform optimum tightening using any tightening member, and while using a torque variation rate for a resin-based member, a torque variation amount for a metal-based member I thought about using. The means for that is the means described in claim 2,
Motor control means for controlling rotation and stop of the motor, and torque estimation means for estimating the tightening torque of the output shaft of the motor, and using the rotational force of the motor, a resin-based member or a metal-based member A tightening tool for tightening screws, bolts, and the like, and determining a torque fluctuation amount as a ratio of a change in the tightening torque with respect to a change in the rotation angle or time of the motor, and rotating the motor A torque fluctuation rate, which is a ratio of the change in the torque fluctuation amount with respect to a change in angle or time, is obtained, and when the torque fluctuation rate exceeds about a predetermined determination start reference value and then becomes about 0 or less, Judgment is made whether the tightening torque exceeds the member judgment torque, which is the boundary value between the maximum tightening torque of the resin-based member and the maximum tightening torque of the metal-based member. When it is determined that the tightening of the resin-based member has been completed, a stop command is output to the motor control unit. On the other hand, if the member determination torque is exceeded, the rotation command is continuously output to the motor control unit. And a tightening judging means for judging that the fastening of the metal-based member is completed when the torque fluctuation amount is about 0 or less and outputting a stop command to the motor control means. To do.
[0016]
Next, the inventors of the present application are to deal with a case where the tightening torque T is temporarily increased due to an assembly failure caused by uneven thread grooves or a shift of the center axis of a bolt and a nut. When it is determined that the tightening has been completed with respect to the means described in claim 1 or 2, the tightening torque is temporarily reduced due to an assembly failure or the like. It is determined whether or not the malfunction determination torque set slightly larger than the maximum torque in the case of rising, and if the malfunction determination torque is not exceeded, it is determined that the malfunction or the like has occurred, and While continuing to output the rotation command to the motor control means, if the malfunction determination torque is exceeded, it is determined that the screw or the like is properly tightened and a stop command is output to the motor control means. With attached judgment means It decided to adopt the means described in claim 3 characterized in that.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
(Configuration of impact tightening tool of this embodiment)
Next, each means for solving the above-described problem will be described in detail as a more specific embodiment. First, regarding the means described in claim 1, as described above, the inventors of the present application, with respect to the resin-based member, have a torque fluctuation rate that is not a torque fluctuation amount but a change in the torque fluctuation amount. It was found that the optimum tightening state can be obtained without damaging the resin-based member by stopping the tightening when the value becomes zero.
[0027]
The configuration of the impact tightening tool for that purpose is as shown in FIG. 1, and a desired tightening torque operated by the operator is set with respect to the configuration of the conventional impact tightening tool shown in FIG. The limit torque setting device 14c is eliminated, and the set torque set by the limit torque setting device 14c is compared with the estimated tightening torque obtained by the torque estimating unit 8 to output a control command to the motor 1. In place of the tightening determination unit 9a, a tightening determination unit 9 is provided that automatically performs a predetermined calculation (to be described later) and automatically determines completion of tightening based on the estimated tightening torque obtained by the torque estimation unit 8. It is a thing.
[0028]
(Steady operation of impact tightening tool)
First, the steady operation of the impact tightening tool will be described with reference to FIG. 1 and FIG. 2. When the trigger 12 is retracted by the operator (step A1), the motor control unit 10 performs the retraction. The rotation is detected and a rotation command is output to the motor control circuit 11. Based on the command, the motor control circuit 11 controls the rotation of the motor 1 (step A2). When the motor 1 rotates in response to the PWM output from the motor control circuit 11, the frequency generator 6 generates a frequency signal proportional to the rotation speed, and the waveform shaping circuit 7 outputs the frequency signal to the output shaft 5 (motor 1), a pulse signal having a pulse width corresponding to the rotation speed of the rotor is output.
[0029]
Next, based on the pulse signal, a hit detection process described later is performed (step A3), and the operator releases the trigger 12, or the tightening determination unit 9 shuts down the motor control unit 10 in step A3. When an OFF command is output (step A4), the motor control unit 10 outputs a stop command to the motor control circuit 11, and the motor control circuit 11 that has received the stop command outputs a PWM output to the motor 1. The motor 1 is stopped and the stop control of the motor 1 is performed (step A5), and a standby state is prepared for the next operation (step A6).
[0030]
(Beat detection in impact tightening tool of this embodiment)
By the way, the hit detection process in step A3 described above is, as shown in FIGS. 1 and 3, in the torque estimation unit 8, the pulse signal input from the waveform shaping circuit 7 changes from Low to High, or High. When a change from low to low, that is, when a pulse edge occurs, an interrupt is generated, the pulse edge is counted (step B1), and the frequency generator as the rotation speed detection means is substituted for the rotation angle detection means Then, by obtaining the pulse width w [k] from the difference between the two count values before and after, an equivalent value of the rotation speed (corresponding to the reciprocal of the speed) that is the original function is detected (step B2).
[0031]
Then, according to the following equations (1) and (2), the average pulse width w obtained by moving and averaging the pulse width w [k] for J and K, respectively. _a1 , W _a2 As shown in equation (3). _a1 To w _a2 The speed fluctuation amount v [k] is obtained from the difference between the average pulse widths obtained by subtracting.
[Expression 1]

[Expression 2]

[Equation 3]

[0032]
Then, based on the following equation (4), an acceleration fluctuation amount a [k], which is a difference between the speed fluctuation amounts, is obtained by subtracting L values moved from the speed fluctuation amount v [k]. The acceleration fluctuation amount a [k] serves as a band-pass filter, and can accurately capture acceleration fluctuations without being affected by noise or the like from PWM. Note that L shown in the equation (4) is determined so as to obtain, for example, the total number of pulses generated by one rotation of the motor, that is, the value before one rotation (step B3).
[Expression 4]

[0033]
Next, the torque estimation unit 8 estimates that a hit has occurred when the acceleration fluctuation amount a [k] obtained as described above exceeds an arbitrarily determined threshold value. When the occurrence of the above is estimated (step B4), a tightening determination process described later is performed (step B5). In addition, although the inventors of this application also have a method of estimating the generation | occurrence | production of an impact by detecting an impact sound with a microphone, since an impact may be misestimated by the vibration sound of the motor 1 or the speed reducer 2, He points out that the above estimation method is preferable.
[0034]
(Torque estimation method in this embodiment)
Next, in describing the tightening determination process in step B5 described above, a tightening torque estimation method will be described first. As an example of the method, the inventors of the present application have proposed a method for estimating the tightening torque from the rotation speed of the motor and the rotation amount of the motor between hits in Japanese Patent Application No. 11-166024. This method is derived from the balance of kinetic energy for each impact, and is based on the relationship that the energy consumed by tightening and the energy given to the anvil provided on the output shaft by hammering are approximately equal. This is a method for estimating the tightening torque.
[0035]
More specifically, as shown in FIG. 4, the rotation angle θ and the tightening torque T of the output shaft 5 are expressed by a nonlinear function of T = τ (θ), and the nonlinear function τ is expressed by the rotation angle θ. While the integrated value is the energy consumed by tightening, the moment of inertia J of the anvil is calculated from the square value of the rotational speed ω of the output shaft. _a Since half of the value obtained by multiplying is the energy given to the anvil by hammering, the estimated tightening torque can be obtained by putting these two energies equivalent.
[0036]
For example, in FIG. 4, the hammer hits each with the rotation angle θ. ₁ , Θ ₂ ..., θ _n As shown in the following equation (5), the nonlinear function τ is represented by the interval [θ _n , Θ _{n + 1} ] To obtain the energy E _n , Rotation angle between striking φ _n (= Θ _{n + 1} −θ _n ) Is the interval [θ _n , Θ _{n + 1} ] Average torque T _na It becomes.
[Equation 5]

[0037]
On the other hand, as shown in the following equation (6), when the impact occurs θ _n Rotational speed ω _n From the square value of, the moment of inertia J of the anvil _a Half of the value obtained by multiplying by _n Energy E given to the anvil by hammering the hammer _ni It becomes.
[Formula 6]

[0038]
Where energy E _n And energy E _ni Are equivalent to each other, and substituting (6) into (5) and rearranging the average torque T _na Estimated tightening torque T _nh The following formula (7) is obtained, and the estimated tightening torque T _nh (Hereinafter, estimated tightening torque T _h And). In addition to the torque estimation method, the inventors of the present application use a torque sensor, estimate from the current and voltage of the motor 1, the traveling angle of the output shaft 5, and the amount of rebound of the hammer 3. Also pointed out that it is good.
[Expression 7]

[0039]
(Tightening determination in impact tightening tool of this embodiment)
With the above torque estimation method in mind, the tightening determination process in step B5 described above will be described with reference to FIGS. 1 and 5. First, the torque estimation unit 8 first calculates the count number C between hits. _i And count the number C according to the following equation (8). _i And the rotation angle φ of the output shaft 5 per count. _n Ask for. The rotation angle of the output shaft 5 per count is from 2π, and the total count number C counted by the torque estimation unit 8 during one rotation of the output shaft 5. _a (Step C1).
[Equation 8]

[0040]
Further, according to the following equation (9), the rotation angle 2π / C of the output shaft 5 per count _a Mean pulse width w _aa The point at which the impact occurs is θ _n Rotational speed ω _n Is calculated (step C2).
[Equation 9]

[0041]
And the rotation angle φ between strikes obtained by the equations (8) and (9), respectively. _n And when the impact occurs θ _n Rotational speed ω _n Can be calculated according to the above equation (7) to obtain the estimated tightening torque (step C3). Next, the torque estimation unit 8 calculates the estimated tightening torque T _h Is output to the tightening determination unit 9, and the tightening determination unit 9 first calculates the estimated tightening torque T according to the following equations (10) and (11), respectively. _h Average tightening torque T obtained by moving average [k] M and N _a1 , T _a2 As shown in equation (3). _a1 To T _a2 From the difference in average tightening torque obtained by subtracting _q [k] is obtained.
[Expression 10]

[Expression 11]

[Expression 12]

[0042]
Next, the tightening determination unit 9 performs the torque fluctuation amount T according to the equations (13) and (14), respectively. _q Average torque fluctuation amount T obtained by moving and averaging [k] O and P _qa1 , T _qa2 As shown in equation (15). _qa1 To T _qa2 The torque fluctuation rate T is calculated from the difference in the average torque fluctuation obtained by subtracting _v [k] is obtained (step C4). In addition, the inventors of the present application indicate that the torque fluctuation amount T _q Or torque fluctuation rate T _v However, it is pointed out that it is better to take a moving average in consideration of noise.
[Formula 13]

[Expression 14]

[Expression 15]

[0043]
Where the number of hits θ _n Estimated tightening torque T against _h , Torque fluctuation amount T _q , Torque fluctuation rate T _v The process after step C4 will be described with reference also to FIG. 6 showing the transition of the torque. _v However, when it exceeds a determination start reference value A that is arbitrarily determined in consideration of noise or the like (step C5) and becomes 0 or less (step C6), a stop command is output to the motor control unit 10. Thus, a shut-off process for stopping the rotation of the motor 1 is performed (step C7). In other cases, the tightening is continued and the tightening determination process is terminated.
[0044]
Thus, the torque fluctuation rate T _v The point where becomes 0 is the maximum tightening torque T _max By stopping the fastening operation at the fastening completion point, the fastening can be completed without destroying the resin member by fastening. Torque fluctuation amount T _q When the point becomes 0, the maximum tightening torque T _max It goes without saying that the member is destroyed. Further, the reason why the inventors of the present application set the determination start reference value A is that the torque fluctuation rate T at the beginning of tightening. _v This is because it is necessary to eliminate such a case because 0 indicates 0 and may become 0 due to noise or the like.
[0045]
[Second Embodiment]
(Basic idea in this embodiment)
Next, although the means described in claim 2, the inventors of the present application can provide an impact tightening tool capable of optimally tightening the resin-based member in the first embodiment. Therefore, it is thought that the optimum tightening can be performed no matter what tightening member is used, and the torque fluctuation rate T is applied to the resin-based member. _v It was considered to stop the tightening when the torque fluctuation amount of the metal-based member becomes zero while the tightening is stopped when the value becomes zero.
[0046]
For this purpose, it is necessary to determine whether the member is a resin-based member or a metal-based member. _max Paying attention to the difference between the members, the maximum tightening torque T of various resin-based members and metal-based members _max The maximum tightening torque T in the resin-based member _max The largest of these, and multiple maximum tightening torques T for metal-based members _max A member determination torque serving as a threshold is provided at the boundary with the smallest one of the estimated tightening torque T _h Proposes to determine a member depending on whether or not exceeds the member determination torque.
[0047]
(Tightening determination in impact tightening tool of this embodiment)
More specifically, as in the tightening determination process shown in FIG. 7, the torque estimation unit 8 calculates the rotation angle φ between hits in the same manner as in the first embodiment. _n Is calculated (step C1), and the point of occurrence of impact θ _n Rotational speed ω _n Is calculated (step C2), and the tightening torque T is estimated (step C3). The tightening determination unit 9 then calculates the estimated tightening torque T calculated in step C3. _h From the torque fluctuation amount T _q And torque fluctuation rate T _v Is calculated (step C4).
[0048]
Here, the number of impacts θ when the resin-based member is tightened _n Estimated tightening torque T against _h , Torque fluctuation amount T _q , Torque fluctuation rate T _v The process after step C4 will be described with reference to FIG. 8 (a) showing the transition of the torque. The tightening determination unit 9 of the present embodiment initially has a torque fluctuation rate T. _v The tightening determination is performed at (Step D1). Then, as in the first embodiment, the torque fluctuation rate T _v Exceeds the predetermined determination start reference value A (step C5), and the fastening completion point θ of the resin-based member having become 0 or less _r (Step C6), the estimated tightening torque T _h Is the member determination torque T ₁ And the member determination torque T ₁ (Step D2), it is determined that the resin-based member is tightened, and the shut-off process is performed (step C7).
[0049]
On the other hand, in step D2, as shown in FIG. 8B, the member determination torque value T ₁ If it exceeds the upper limit, it is determined that the metal-based member is tightened and the tightening point θ of the resin-based member is completed. _r If the tightening is stopped at step 3, the tightening will be insufficient, so that the tightening is continued and the torque variation amount determination mode is entered (step D3). _q Tightening completion point θ _m (Step D4), the shutoff process is performed (step C7), and the torque fluctuation amount T _q If is not less than or equal to 0, tightening is continued and the tightening determination process is terminated.
[0050]
Thus, in the impact tightening tool of the present embodiment, the torque fluctuation rate T at the beginning of tightening. _v Tightening determination using resin _r When it is determined that the estimated tightening torque T _h Is the member determination torque T ₁ If it exceeds, the metal member is judged to be tightened and the tightening is continued, and the torque fluctuation amount T _q Tightening determination using metal _m Because it is designed to shut off when it is determined that the maximum pressure has been reached, no matter what tightening member is used, the tightening member can be obtained without being damaged and an optimum tightening state can be obtained. Can do.
[0051]
Other configurations and operations are the same as those in the first embodiment, and are not specifically described here. Further, in the following description of each embodiment, the same processes are denoted by the same reference numerals as shown in FIG. Or omitted.
[0052]
[Third Embodiment]
(Basic idea in this embodiment)
Next, the means described in claim 3, the inventors of the present application provide an impact tightening tool capable of obtaining an optimum tightening state with any tightening member in the second embodiment. As a result, the tightening completion point θ shown in FIG. _Three First, the torque fluctuation amount T _q (Torque fluctuation rate T _v Is also applicable) is 0 ₁ In view of this point, I thought that it would be possible to deal with the problem of stopping the tightening. As shown in the figure, the maximum torque when the tightening torque T is temporarily increased due to the malfunction is Attention was paid to the fact that the tightening torque T at the completion point of tightening is very often smaller.
[0053]
Therefore, the inventors of the present application investigate the maximum torque when the tightening torque T is temporarily increased based on such a point of interest for each of various problems, and among the plurality of maximum torques in the problem. A failure determination torque serving as a threshold is provided so that the torque is slightly larger than the largest torque, and the estimated tightening torque T _h The estimated tightening torque T depends on whether the torque exceeds the failure determination torque. _h It is proposed to determine whether the increase in the amount is due to sitting or due to a malfunction.
[0054]
(Tightening determination in impact tightening tool of this embodiment)
More specifically, the tightening determination process shown in FIG. _n Estimated tightening torque T against _h Referring to FIG. 10 (a) showing the transition of the above, the operation when fastening the resin-based member will be described. First, the torque fluctuation rate T _v Etc. (steps C1 to C4), and at the beginning of tightening, the torque fluctuation rate T _v Tightening determination is performed with (Step D1), and the number of hits is θ ₁ Torque fluctuation rate T _v Has already exceeded the determination start reference value A (step C5) and has become 0 or less (step C6), the estimated tightening torque T _h Is the member determination torque T ₁ And the member determination torque T ₁ (Step D2), it is determined that the resin-based member is tightened.
[0055]
At this time, the tightening determination unit 9 of the present embodiment performs the estimated tightening torque T _h Is the failure determination torque T ₂ To determine whether or not the torque exceeds the failure determination torque T ₂ (Step E1), it is determined that some trouble has occurred, and the torque fluctuation rate T _v Is cleared (step E2), tightening is continued, and the tightening determination process is terminated. The number of hits is θ ₂ Torque fluctuation rate T _v However, since the determination start reference value A is not exceeded (step C5), the tightening determination process is terminated by continuing the tightening in the same manner.
[0056]
On the other hand, the number of hits is θ _r Torque fluctuation rate T _v Has already exceeded the determination start reference value A (step C5) and has become 0 or less (step C6). _h Is the member determination torque T ₁ And the member determination torque T ₁ (Step D2), it is determined that the resin-based member is tightened. Next, the estimated tightening torque T _h Is the failure determination torque T ₂ To determine whether or not the torque exceeds the failure determination torque T ₂ (Step E1), it is determined that the tightening member is properly tightened (sitting) without causing any trouble, and the shut-off process is performed (step S1). C7).
[0057]
When the metal member shown in FIG. 10B is tightened, the tightening point θ of the resin member is completed. _r The estimated tightening torque T _h Is the member determination torque T ₁ (Step D2), the mode shifts to the torque fluctuation amount determination mode (step D3), and the torque fluctuation amount T _q Tightening completion point θ _m (Step D4), the estimated tightening torque T _h Is the failure determination torque T ₂ To determine whether or not the torque exceeds the failure determination torque T ₂ Is exceeded (step E1), a shut-off process is performed (step C7).
[0058]
Thus, in the impact tightening tool of this embodiment, the torque fluctuation rate T _v Or torque fluctuation amount T _q Estimated tightening torque T when is less than 0 _h Is the failure determination torque T ₂ Since the shut-off is performed when the pressure exceeds the limit, the optimum tightening can be performed even if there are some problems in assembly. Other configurations and operations are the same as those in the above-described embodiments, and thus will not be described here.
[0059]
[ Reference example 1 ]
(Basic idea in this embodiment)
The inventors of the present application employ the failure determination torque T2 in the third embodiment, so that the impact tightening tool can perform optimum tightening even if there is a slight failure in assembly. However, since the defect determination torque T2 is not changed, the estimated tightening torque Th at the tightening completion points θr and θm is smaller than the defect determination torque T2 and is outside the design range. When the member is tightened, the tightening operation may be continued even though the tightening is completed.
[0060]
On the other hand, before the tightening completion points θr and θm, the tightening member outside the design range in which the estimated tightening torque Th when the torque fluctuation rate Tv or the like becomes 0 is larger than the failure determination torque T2 is tightened. If excessive noise is applied and the torque exceeds the failure determination torque T2, the tightening operation may be stopped although the tightening is not completed. Therefore, the inventors of the present application can change the malfunction determination torque T2 in order to solve such a problem. Hand Propose a stage.
[0061]
(Configuration of impact tightening tool of this embodiment)
The specific configuration of the impact tightening tool for this purpose is as shown in FIG. 11, which is connected to the tightening determination unit 9 in comparison with the configuration of the conventional impact tightening tool shown in FIG. Torque T ₂ Is provided with a failure determination torque setting device 14a. The failure determination torque setting unit 14a uses a variable resistor or the like, for example, to determine the failure determination torque T ₂ Can be set freely.
[0062]
In this manner, by providing the setting device 14a, the failure determination torque T is determined according to a fragile fastening member or a sturdy member, which is a target for the operator at the work site. ₂ Therefore, it is possible to avoid the above-mentioned non-stop or mid-stop and obtain an optimum tightening state. Other configurations and operations are the same as those in the above-described embodiments, and thus will not be described here.
[0063]
[ Reference example 2 ]
(Basic idea in this embodiment)
The inventors of the present application Reference example 1 However, by providing the failure determination torque setting device 14a, the above-described non-stop or mid-stop can be avoided even when a tightening member outside the design range is tightened or excessive noise is added. When a tightening operation is performed by mixing a member having a small tightening torque and a large member at the time of completion of tightening, it is necessary to set a failure determination torque T2 according to each member. There was a fear of bringing about.
[0064]
On the other hand, the inventors of the present application have repeated trial and error as to whether there is a clue that can cope with such a problem, and as shown in FIG. The maximum value of the ascending is often proportional to the magnitude of the tightening torque of the tightening member at the completion of tightening, and the maximum value is the tightening torque measured first (estimated tightening). Torque T _h ) Is often the largest, and the estimated tightening torque T from the start to any number of revolutions _h The maximum torque is obtained from the transition of the failure, and the failure determination torque T is determined according to the maximum torque. ₂ I realized that the above problem can be solved by setting.
[0065]
Therefore, the inventors of the present application investigated the number of times required to complete the tightening of all the tightening members to be tightened in order to realize such a solution, and among them, the member having the smallest required number of rotations The rotation speed is determined as the determination rotation speed, the maximum torque is obtained from the estimated tightening torque Th from the start to the rotation of the determination rotation speed, and a value obtained by adding a minute value to the maximum torque is determined as a failure determination. Torque T2 Hand Propose a stage.
[0066]
(Trouble determining torque T in this embodiment ₂ About setting)
As shown in FIG. 12, the configuration of the impact tightening tool for realizing the means includes a torque estimation unit 8 and a tightening determination unit 9 as compared with the configuration of the conventional impact tightening tool shown in FIG. A connected failure determination torque automatic setting unit 15 is provided. The operation is the same as the tightening determination process shown in FIG. 13. First, the rotation angle φ between strikes is calculated from the torque estimation unit 8. _n Is input (step C1), the total rotational speed ψ of the output shaft 5 from the start to the present based on the following equation (16) _all (Step F1).
[Expression 16]

[0067]
Next, the number of hits θ _n Estimated tightening torque T against _h Referring to FIG. 14 showing the transition of the automatic setting unit 15, the explanation of the operation of the automatic setting unit 15 will be continued. _all Is the judgment speed ψ _h It is judged whether or not the above has been reached (step F2), and its rotational speed ψ _h If not exceeded, the estimated tightening torque T calculated so far _h Any torque T _g Is added to the value for failure determination torque T ₂ (Step F3), the determination rotational speed ψ _h Exceeds ψ after starting _h Estimated tightening torque T until rotation _h Of torque T _m1 And any minute torque T _g Is added to the value for failure determination torque T ₂ (Step F4).
[0068]
In this way, even when a tightening operation is performed by mixing a member with a small tightening torque and a member with a large tightening torque when tightening is completed, Since it is not necessary to set the determination torque, work efficiency can be improved. The maximum torque T _m1 Small torque T _g If the torque is not applied, the failure determination torque T is easily applied. ₂ It is because there is a risk of exceeding. Further, the processes after Steps F3 and F4 are the same as the processes of Steps C2 to C7 of FIG. 9 used in the third embodiment, and other configurations and operations are the same as those of the above-described embodiments. There are no specific explanations here.
[0069]
[ Reference example 3 ]
(Basic idea in this embodiment)
The inventors of the present application Reference example 2 In this case, the maximum torque Tm1 is obtained from the start to the time when the determination rotational speed ψh is rotated, and the value obtained by adding the constant value Tg to the maximum torque Tm1 is set as the failure determination torque T2, so that Even when a member having a small tightening torque and a member having a large tightening torque are mixed to perform a tightening operation, an appropriate tightening state has been successfully obtained.
[0070]
However, the estimated tightening torque T immediately after starting _h Is too small due to some disturbance, or vice versa, the failure judgment torque T is adjusted in accordance with the estimated tightening torque. ₂ Is set to be too small or too large, there is a possibility that the tightening may be stopped or the tightening operation may be continued without reaching the tightening completion point. Therefore, the inventors of the present application have solved the problem determination torque T in order to solve such a problem. ₂ It is proposed to give a predetermined upper and lower limit so that is not too small or too large.
[0071]
(Trouble determining torque T in this embodiment ₂ About setting)
More specifically, it is as in the tightening determination process shown in FIG. _n Is input (step C1), the total rotational speed ψ of the output shaft 5 from the start to the present _all (Step F1), and the total rotational speed ψ _all Is the judgment speed ψ _h It is determined whether or not the above has been reached (step F2). And the malfunction determination torque automatic setting part 15 of this embodiment is the said determination rotation speed (psi). _h If not exceeded, the failure determination torque T ₂ , Initial torque T _d The determination torque T ₂ Is not changed (step G1).
[0072]
Next, the determined rotational speed ψ _h Stroke number θ _n Estimated tightening torque T against _h Referring to FIG. 16 (a) showing the transition of the automatic setting unit 15 and the like, the description of the operation of the automatic setting unit 15 will be continued. _h Estimated tightening torque T until rotation _h Of torque T _m1 And any minute torque T _g Is added to the value for failure determination torque T ₂ Temporary setting value T _2P (Step F4a) and its temporary set value T _2P Is the initial set torque T _d In the above case (step G2), it is determined that the determination value is too large, and the initial set torque T _d The failure determination torque T ₂ (Step G3).
[0073]
On the other hand, as shown in FIG. 16B, in step G2, the temporary set value T _2P Is the initial set torque T _d The allowable lower limit torque T which is below and arbitrarily determined in advance _L In the following cases (step G4), it is determined that the determination value is too small, and the allowable lower limit torque T _L The failure determination torque T ₂ (Step G5). In step G4, the temporary setting value T _2P Is the allowable lower limit torque T _L If it is above, it is determined that the determination value is an appropriate value, and the temporary setting value T _2P The failure determination torque T ₂ (Step G6).
[0074]
In this way, the estimated tightening torque T immediately after starting _h However, even if it is too small due to some disturbance, or vice versa, it will stop tightening without reaching the proper tightening completion point, or the tightening operation will continue. The optimum tightening state can be obtained. The processes after steps G1, G5, and G6 are the same as the processes of steps C2 to C7 of FIG. 9 used in the third embodiment, and other configurations and operations are the same as those of the above-described embodiments. Since they are the same, they are not specifically described here.
[0075]
[ Reference example 4 ]
(Basic idea in this embodiment)
The inventors of the present application described above Reference Example 2 and Reference Example 3 In this case, the determination rotational speed ψh is introduced, and even when a tightening operation is performed by mixing a member with a small tightening torque and a large member when tightening is completed, it is possible to obtain an appropriate tightening state. However, by adopting such a determination rotational speed ψh, it has been found that the effect intended by the inventors of the present application has another effect. Even if the failure determination torque T2 employed in the third embodiment is not used, the tightening is continued even if the torque fluctuation rate Tv or the like becomes 0 while the rotation speed has not been reached. Hand Appropriate tightening can be obtained by using a step.
[0076]
(Tightening determination in impact tightening tool of this embodiment)
More specifically, it is the same as the tightening determination process shown in FIG. 17, and in the flowchart of FIG. 9 showing the third embodiment, instead of steps E1 and E2, the total rotational speed ψ _all Is the judgment speed ψ _h Step H is used to determine whether or not the rotation speed ψ _h It is determined whether or not an assembly failure due to a shift of the central axis of the bolt and the nut has occurred.
[0077]
More in detail, the number of hits θ _n Estimated tightening torque T against _h The operation of the present embodiment will be described with reference to FIG. _v It is determined that the tightening of the resin-based member whose value is 0 or less is θ ₁ , Θ ₂ (Step C6), the total rotational speed ψ _all Is the judgment speed ψ _h If both of these points are _h Is not exceeded (step H), it is determined that some trouble has occurred, the tightening is continued, and the tightening determination process is terminated.
[0078]
On the other hand, the torque fluctuation rate T _v Is less than or equal to 0 _r And torque fluctuation amount T _q Is determined to be the completion of tightening of the metal-based member having a value of 0 or less _m The total number of revolutions ψ _all Is the judgment speed ψ _h If both of these points are _h (Step H), it is determined that the fastening member is properly tightened (sit down) without any malfunction, and the shut-off process is performed (step S). C7).
[0079]
Note that FIG. 18 used in the description of the present embodiment shows an example of the fastening of the metal-based member, and the fastening completion point θ of the resin-based member. _r Estimated tightening torque T _h Is the member determination torque T ₁ Since this is the case (step D2), it is determined that the metal member is tightened, the process shifts to the fluctuation amount mode (step D3), and the tightening point θ of the metal member is reached. _m As described in the second embodiment, the shut-off process is performed (step C7).
[0080]
Thus, when it is determined that tightening is complete, the total rotational speed ψ _all Is the judgment speed ψ _h To determine whether the rotation speed exceeds ψ _h By shutting off when exceeding the above, optimum tightening can be performed even if there are some problems in assembly. Other configurations and operations are the same as those in the third embodiment, and are not specifically described here.
[0081]
[ Reference Example 5 ]
(Basic idea in this embodiment)
The inventors of the present application Reference example 4 However, the adoption of the determination rotational speed ψh has found another effect that optimum tightening can be performed even if there is a slight malfunction in assembly, but the determination rotational speed ψh is unchanged. Therefore, when tightening a tightening member outside the design range where tightening is completed at a rotational speed smaller than the judged rotational speed ψh, the tightening operation continues even though the tightening has been completed. There was a fear of being done.
[0082]
On the other hand, when mixing and tightening a member that requires an extremely small number of times until tightening and a member that requires an extremely large number of times until tightening, the tightening operation is prevented from continuing as described above. Therefore, the determination rotational speed ψh is set in accordance with a member that requires an extremely small number of times until tightening, but in that case, judging from the rotational speed of a member that requires a very large number of times until tightening, the determination rotational speed Since ψh is a very small number of revolutions, if there is an increase in the estimated tightening torque Th due to a slight assembly problem between the two revolutions, the tightening is not completed. Therefore, there was a risk of stopping the tightening operation. Therefore, the inventors of the present application can change the determination rotational speed ψh to solve such a problem. Hand Propose a stage.
[0083]
(Configuration of impact tightening tool of this embodiment)
The specific configuration of the impact tightening tool for this purpose is as shown in FIG. 19, which is connected to the tightening determination unit 9 in comparison with the configuration of the conventional impact tightening tool shown in FIG. A determination rotational speed setter 14b capable of changing the number ψh is provided. This determination rotation speed setting unit 14b Reference example 1 In the same manner as the failure determination torque setting unit 14a shown in FIG. 5, the determination rotational speed ψh may be set freely using, for example, a variable resistor.
[0084]
In this way, by providing the setting device 14b, the determination rotational speed ψ according to each of the tightening member having a low rotational speed or the member having a high rotational speed as a target at the work site by the operator. _h Therefore, it is possible to avoid the above-mentioned non-stop or mid-stop and obtain an optimum tightening state. Other configurations and operations are the same as those in the above-described embodiments, and thus will not be described here.
[0085]
[ Reference Example 6 ]
(Basic idea in this embodiment)
The inventors of the present application can perform optimum tightening without damaging the tightening member in any of the above-described embodiments, even if any tightening member is used or there is a slight problem in assembly. Although the present inventors have been able to provide a tightening tool that can be performed, the present inventors' willingness to create does not remain there, and a tightening member that has already been tightened is erroneously tightened. I thought that it would be possible to deal with this case, and I thought to use the fact that the value of the estimated tightening torque Th appears as a large value from the beginning when the already tightened tightening member is tightened.
[0086]
Therefore, the inventors of the present application pay attention to the fact that the maximum tightening torque Tmax again differs depending on the member in order to use such a phenomenon, and investigate the maximum tightening torque Tmax of various resin-based members to obtain resin-based members. The smallest tightening torque among the plurality of maximum tightening torques Tmax is determined as the additional tightening determination torque, and the tightening member already tightened according to whether the estimated tightening torque Th exceeds the additional tightening determination torque To determine whether the tightening has been done by mistake. Hand Propose a stage.
[0087]
(Additional tightening determination in impact tightening tool of this embodiment)
More specifically, in the tightening determination process shown in FIG. 20, in step C5 in the flowchart of FIG. 9 showing the third embodiment, the torque fluctuation rate T _v Is determined not to exceed the determination start reference value A, that is, when it is NO, the estimated tightening torque T _h Tightening judgment torque T _Three Step J for determining whether or not the torque exceeds T _Three And whether or not the determination torque T _Three Is exceeded, the system is shut off (step C7).
[0088]
More in detail, the number of hits θ _n Estimated tightening torque T against _h The operation of the present embodiment will be described with reference also to FIG. 21 showing the transition of the torque fluctuation rate T when the tightening is performed. _v Etc. are extremely small and do not exceed the determination start reference value A (step C5). However, even in this case, θ in FIG. ₂ As shown in FIG. 4, since the judgment start reference value A may not be exceeded, the estimated tightening torque T _h Tightening judgment torque T _Three And the determination torque T as shown in FIG. _Three Is exceeded (step J), shut-off is performed on the assumption that retightening has been performed (step C7).
[0089]
On the other hand, the determination torque T _Three Is not exceeded (step J), θ in FIG. ₂ In this way, the tightening operation is continued by determining that an appropriate tightening operation is being performed instead of the additional tightening. Thus, the torque fluctuation rate T _v Without exceeding the determination start reference value A and the estimated tightening torque T _h Tightening judgment torque T _Three When it is exceeded, it is determined that additional tightening has occurred, and shut-off eliminates unnecessary work, and energy consumed by additional tightening can be reduced.
[0090]
The determination start reference value A in the present embodiment is the torque fluctuation rate T when additional tightening is performed. _v Etc. are determined so as not to exceed the reference value A. Moreover, in this embodiment, since it demonstrated on the basis of 3rd Embodiment, several maximum tightening torque T in a resin-type member is demonstrated. _max The smallest tightening torque is set as the additional tightening determination torque. However, in the case where only the metal member is tightened, a plurality of maximum tightening torques T in the metal member are used. _max Needless to say, the smallest torque is adopted.
[0091]
[ Reference Example 7 ]
(Basic idea in this embodiment)
The inventors of the present application Reference Example 6 In the above embodiments, in order to further improve the work efficiency, in the case where the tool is stopped halfway due to an erroneous determination, the tightening is performed. We paid attention to the fact that the operator had to pull the trigger again in order to continue the work, which was troublesome. Therefore, in order to improve such a situation, the inventors of the present application perform rotation control of the impact tightening tool again when a predetermined time has passed without the trigger being released. Hand Propose a stage.
[0092]
(Steady processing in the impact tightening tool of this embodiment)
More specifically, as shown in the tightening determination process shown in FIG. 22, after step A5 in the flowchart of FIG. 2 showing the first embodiment is processed, timer measurement is started (step I1). The trigger is not released (step A6), and the predetermined time T _m Is passed (step I2), the rotation control of the motor 1 is performed again (step A2). By doing in this way, in each of the above-described embodiments, even when it is stopped halfway due to an erroneous determination, the predetermined time T _m Since the rotation control is automatically started when elapses, it is not necessary for the operator to re-trigger the trigger and the workability can be improved.
[0093]
[About supplementary items in each embodiment]
In each of the above embodiments, the impact tightening tool has been described. However, the inventors of the present application are not limited to such a tightening tool, and can be widely applied to general tightening tools. It can be used, and a frequency generator is used as the rotation speed detection means, and the pulse edge is counted to substitute for the rotation angle detection means. However, the present invention is not limited to this, and can be replaced by an encoder or a potentiometer. It is possible to do it. In order to obtain the rotational speed with an encoder or the like, it is general to obtain the rotational speed by taking a difference.
[0094]
Further, as described in the first embodiment, the inventors of the present application have a torque fluctuation rate T. _q And torque fluctuation rate T _v Is calculated based on the difference of the moving average, but because noise is taken into account, the difference between the current value and the previous value may be taken, not only the differential value based on the rotation angle θ, It argues that it may be a differential value over time. That is, the present inventors' claims are more specifically expressed as follows: torque fluctuation amount T _q Means the ratio of the change in the tightening torque T with respect to the change in the rotation angle θ or time t as shown in the equation (17).
[Expression 17]

[0095]
On the other hand, torque fluctuation rate T _v Is a torque fluctuation amount T with respect to a change in the rotation angle θ or time t as shown in the equation (18). _q It means the rate of change.
[Formula 18]

[0096]
Furthermore, the inventors of the present application, in each of the embodiments described above, have a torque fluctuation amount T. _q , Torque fluctuation rate T _v It is asserted that tightening is determined when the value exceeds a predetermined threshold and becomes 0 or less, but it may be determined that the tightening is determined when the value becomes equal to or less than a predetermined threshold. Along with the torque fluctuation amount T _q Instead of exceeding a predetermined threshold value or together with the condition, the torque fluctuation amount T _q The torque fluctuation amount T during which the positive value continues _q It is pointed out that a method may be used in which a sum of the above is obtained and a point in time when the sum exceeds a threshold is determined as a fastening completion point.
【The invention's effect】
[0097]
As described above, in the invention according to claim 1, when the torque fluctuation rate exceeds the determination start reference value and then becomes approximately 0 or less, it is determined that the tightening of the screw or the like is completed, Since the motor is stopped, there is an effect that appropriate tightening can be performed without destroying brittle materials such as resin members by tightening.
[0098]
Next, in the invention according to claim 2, when the torque fluctuation rate exceeds the determination start reference value and then becomes about 0 or less, it is determined whether the tightening torque exceeds the member determination torque, If the member determination torque has not been exceeded, it is determined that tightening of the resin-based member has been completed, whereas if the member determination torque has been exceeded, rotation control of the motor is continued and the torque fluctuation amount is When it becomes about 0 or less, it is judged that the tightening of the metal-based member is completed, and the motor is stopped, so that the tightening member is damaged regardless of the tightening member used. Without being able to obtain an optimum tightening state.
[0099]
Next, in the invention according to claim 3, when it is determined that the tightening is completed, it is determined whether the tightening torque exceeds the failure determination torque. If it is determined that a malfunction has occurred and the motor rotation control is continued, if the malfunction determination torque is exceeded, it is determined that the screws are properly tightened and the motor is stopped. Therefore, even if there is a problem in assembly, there is an effect that optimum tightening can be performed.
[Brief description of the drawings]
FIG. 1 is a basic configuration diagram of an impact fastening tool in the present application.
FIG. 2 is a flowchart showing a steady process of an impact tightening tool.
FIG. 3 is a flowchart showing impact detection processing of an impact tightening tool in the present application.
FIG. 4 is a diagram showing a relationship of a tightening torque T with respect to a rotation angle θ.
FIG. 5 is a flowchart showing a tightening determination process for an impact tightening tool according to the first embodiment.
FIG. 6 is a diagram showing a response of an impact tightening tool in the first embodiment, and shows changes in estimated tightening torque Th, torque fluctuation amount Tq, and torque fluctuation rate Tv with respect to the number of hits θn.
FIG. 7 is a flowchart illustrating a tightening determination process for an impact tightening tool according to the second embodiment.
FIG. 8 is a diagram showing the response of the impact tightening tool in the second embodiment, showing the transition of the estimated tightening torque Th, the torque fluctuation amount Tq, and the torque fluctuation rate Tv with respect to the number of impacts θn; (A) is a figure at the time of fastening a resin system member, (b) is a figure at the time of fastening a metal system member.
FIG. 9 is a flowchart illustrating a tightening determination process for an impact tightening tool according to a third embodiment.
FIG. 10 is a diagram showing the response of the impact tightening tool in the third embodiment, showing the transition of the estimated tightening torque Th, the torque fluctuation amount Tq, and the torque fluctuation rate Tv with respect to the number of impacts θn; (A) is a figure at the time of fastening a resin system member, (b) is a figure at the time of fastening a metal system member.
FIG. 11 Reference example 1 It is a block diagram of the impact fastening tool in.
FIG. Reference example 2 It is a block diagram of the impact fastening tool in.
FIG. 13 Reference example 2 It is a flowchart which shows the fastening determination processing of the impact fastening tool in.
FIG. 14 Reference example 2 Is a diagram showing the response of the impact tightening tool, and shows the transition of the estimated tightening torque Th, the torque fluctuation amount Tq, and the torque fluctuation rate Tv with respect to the number of hits θn.
FIG. 15 Reference example 3 It is a flowchart which shows the fastening determination processing of the impact fastening tool in.
FIG. 16 Reference example 3 FIG. 6 is a diagram showing the response of the impact tightening tool in FIG. 6 and shows the transition of the estimated tightening torque Th, the torque fluctuation amount Tq, and the torque fluctuation rate Tv with respect to the number of impacts θn. FIG. 5B is a diagram when the initial set torque Td is greater than or equal to the initial set torque Td, and FIG. 5B is a diagram when the temporary set value T2P is less than or equal to the allowable lower limit torque TL.
FIG. 17 Reference example 4 It is a flowchart which shows the fastening determination processing of the impact fastening tool in.
FIG. 18 Reference example 4 Is a diagram showing the response of the impact tightening tool, and shows the transition of the estimated tightening torque Th, the torque fluctuation amount Tq, and the torque fluctuation rate Tv with respect to the number of hits θn.
FIG. 19 Reference Example 5 It is a block diagram of the impact fastening tool in.
FIG. 20 Reference Example 6 It is a flowchart which shows the fastening determination processing of the impact fastening tool in.
FIG. 21 Reference Example 6 Is a diagram showing the response of the impact tightening tool, and shows the transition of the estimated tightening torque Th, the torque fluctuation amount Tq, and the torque fluctuation rate Tv with respect to the number of hits θn.
FIG. 22 Reference Example 7 It is a flowchart which shows the steady process of the impact fastening tool which concerns on.
FIG. 23 is a configuration diagram of an impact tightening tool in a conventional embodiment.
FIG. 24 is a diagram showing changes in the tightening torque T and the torque fluctuation amount Tq with respect to the number of hits θn in the tightening operation.
FIG. 25 is a diagram for illustrating a conventional tightening determination process, showing changes in the tightening torque T and the torque fluctuation amount Tq with respect to the rotation angle θ.
FIG. 26 is a diagram in the case where it is determined that the tightening is completed when the resin-based member is tightened using the conventional tightening determination process and the torque fluctuation amount Tq becomes zero.
[Fig.27] The thread groove is uneven, the member sandwiched between the bolt and nut is slightly curved, the center axis of the bolt and nut is misaligned, dust is swallowed, the surface of the screw hole It is a figure which shows the case where the tightening torque T rises temporarily by scraping off of the baking coating in the.

Claims (3)

  Motor control means for controlling rotation and stop of the motor, and torque estimation means for estimating the tightening torque of the output shaft of the motor, and tightening screws and bolts using the rotational force of the motor A tightening tool for performing work, wherein a torque fluctuation amount as a ratio of a change in the tightening torque with respect to a change in the rotation angle or time of the motor is obtained, and the torque fluctuation amount with respect to a change in the rotation angle or time of the motor The torque fluctuation rate, which is the rate of change of the torque, is obtained, and when the torque fluctuation rate exceeds about a predetermined determination start reference value and then becomes approximately 0 or less, it is determined that the tightening of the screw or the like has been completed. And a tightening determination means for outputting a stop command to the motor control means.   Motor control means for controlling rotation and stop of the motor, and torque estimation means for estimating the tightening torque of the output shaft of the motor, and using the rotational force of the motor, a resin-based member or a metal-based member A tightening tool for tightening screws, bolts, and the like, and determining a torque fluctuation amount as a ratio of a change in the tightening torque with respect to a change in the rotation angle or time of the motor, and rotating the motor A torque fluctuation rate, which is a ratio of the change in the torque fluctuation amount with respect to a change in angle or time, is obtained, and when the torque fluctuation rate exceeds approximately a determination start reference value, Judgment is made whether the tightening torque exceeds the member judgment torque, which is the boundary value between the maximum tightening torque of the resin-based member and the maximum tightening torque of the metal-based member. When it is determined that the tightening of the resin-based member has been completed, a stop command is output to the motor control unit. And a tightening judging means for judging that the fastening of the metal-based member is completed when the torque fluctuation amount is about 0 or less and outputting a stop command to the motor control means. Tightening tool to do.   When it was determined that the tightening was completed, the tightening torque was set to be slightly larger than the maximum torque when the tightening torque temporarily increased due to an assembly failure or the like. It is determined whether or not the failure determination torque is exceeded.If the failure determination torque is not exceeded, it is determined that the failure or the like has occurred, and the motor control means continues to output the rotation command, 2. A tightening determination means for determining that the screw or the like is properly tightened when a failure determination torque is exceeded and outputting a stop command to the motor control means. Or the fastening tool of Claim 2.

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