JP4765205B2 - High frequency welding control method and control apparatus - Google Patents

High frequency welding control method and control apparatus Download PDF

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Publication number
JP4765205B2
JP4765205B2 JP2001182550A JP2001182550A JP4765205B2 JP 4765205 B2 JP4765205 B2 JP 4765205B2 JP 2001182550 A JP2001182550 A JP 2001182550A JP 2001182550 A JP2001182550 A JP 2001182550A JP 4765205 B2 JP4765205 B2 JP 4765205B2
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welding
frequency
current value
welded
molds
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JP2002370283A (en
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幸三 竹野
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JMS Co Ltd
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JMS Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/04—Dielectric heating, e.g. high-frequency welding, i.e. radio frequency welding of plastic materials having dielectric properties, e.g. PVC
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/80—General aspects of machine operations or constructions and parts thereof
    • B29C66/82—Pressure application arrangements, e.g. transmission or actuating mechanisms for joining tools or clamps
    • B29C66/824—Actuating mechanisms
    • B29C66/8242—Pneumatic or hydraulic drives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/80—General aspects of machine operations or constructions and parts thereof
    • B29C66/83—General aspects of machine operations or constructions and parts thereof characterised by the movement of the joining or pressing tools
    • B29C66/832—Reciprocating joining or pressing tools
    • B29C66/8322—Joining or pressing tools reciprocating along one axis
    • B29C66/83221—Joining or pressing tools reciprocating along one axis cooperating reciprocating tools, each tool reciprocating along one axis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/90—Measuring or controlling the joining process
    • B29C66/91—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
    • B29C66/912—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by measuring the temperature, the heat or the thermal flux
    • B29C66/9131—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by measuring the temperature, the heat or the thermal flux by measuring the heat or the thermal flux, i.e. the heat flux
    • B29C66/91311—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by measuring the temperature, the heat or the thermal flux by measuring the heat or the thermal flux, i.e. the heat flux by measuring the heat generated by Joule heating or induction heating
    • B29C66/91315—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by measuring the temperature, the heat or the thermal flux by measuring the heat or the thermal flux, i.e. the heat flux by measuring the heat generated by Joule heating or induction heating by measuring the current intensity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/90—Measuring or controlling the joining process
    • B29C66/91—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
    • B29C66/914—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux
    • B29C66/9161—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux
    • B29C66/91651—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux by controlling or regulating the heat generated by Joule heating or induction heating
    • B29C66/91655—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux by controlling or regulating the heat generated by Joule heating or induction heating by controlling or regulating the current intensity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/90—Measuring or controlling the joining process
    • B29C66/91—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
    • B29C66/919—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux values or ranges
    • B29C66/9192—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux values or ranges in explicit relation to another variable, e.g. temperature diagrams
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/90—Measuring or controlling the joining process
    • B29C66/91—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
    • B29C66/919—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux values or ranges
    • B29C66/9192—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux values or ranges in explicit relation to another variable, e.g. temperature diagrams
    • B29C66/91951—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux values or ranges in explicit relation to another variable, e.g. temperature diagrams in explicit relation to time, e.g. temperature-time diagrams
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/90—Measuring or controlling the joining process
    • B29C66/94—Measuring or controlling the joining process by measuring or controlling the time
    • B29C66/942—Measuring or controlling the joining process by measuring or controlling the time by measuring the time
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/90—Measuring or controlling the joining process
    • B29C66/94—Measuring or controlling the joining process by measuring or controlling the time
    • B29C66/944—Measuring or controlling the joining process by measuring or controlling the time by controlling or regulating the time
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/90—Measuring or controlling the joining process
    • B29C66/94—Measuring or controlling the joining process by measuring or controlling the time
    • B29C66/949—Measuring or controlling the joining process by measuring or controlling the time characterised by specific time values or ranges
    • B29C66/9492—Measuring or controlling the joining process by measuring or controlling the time characterised by specific time values or ranges in explicit relation to another variable
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/90—Measuring or controlling the joining process
    • B29C66/96—Measuring or controlling the joining process characterised by the method for implementing the controlling of the joining process
    • B29C66/961—Measuring or controlling the joining process characterised by the method for implementing the controlling of the joining process involving a feedback loop mechanism, e.g. comparison with a desired value

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は高周波溶着における制御方法に関し、より詳細には溶着が完了するまで、高周波溶着処理を継続し、溶着が完了したところで、速やかに処理を停止する高周波溶着の制御機構に関する。
【０００２】
【従来の技術】
従来の高周波溶着では、溶着の制御を時間や出力で管理していたため、被溶着物の素材・形状や溶着装置の状態によって、過溶着になったり、溶着不足になることがあり、こうして発生する不良が生産効率を著しく低下させていた。そして、用途や状況によって異なるが、万一 発生した不良品が未然に検出できなければ、大事故につながりかねない。
【０００３】
図７に示すように、従来の高周波溶着では、被溶着物を上下に配した金型で挟み、その金型に高周波エネルギーを加えることによって、被溶着物の一部を溶解し、結合させていた。その際の制御は溶着時間の増減のみであり、被溶着物の素材や装置の状態を考慮しながら、操作する者がカンや経験によって、行っていた。そのため、熟練技術者が必要となり、また熟練者でも不良品発生率を下げるのは非常に困難であった。
【０００４】
本発明者は溶着状態を改善または安定させるため、色々な方法によって制御を試みた。例えば、（被溶着物の）材料温度を調整するため、被溶着物に加熱ユニットを取付けてみたり、金型温度の制御や高周波同調回路の改善のために、電極板の調整を試みたが、いずれも溶着不良の根本的対策にならなかった。その原因は溶着不良を引き起こす要因が多く、それらの要因の変化に制御手段が追随できていないためであると考えられた。しかし、これら全ての要因変化を検出したり、制御するのはたいへん困難であった。
【０００５】
【発明が解決しようとする課題】
本発明の目的は、溶着不良を起こす様々な要因変化によっても、確実に溶着がなされるようにすることである。即ち、材料温度や金型温度、高周波同調回路等の要因変化に影響されずに、常に確実な溶着ができるように制御する高周波溶着の制御方法を提供することであり、さらにこのような制御方法を利用して溶着を行う高周波溶着処理装置を提供することである。
【０００６】
【課題を解決するための手段】
本発明者は、前記の多くの要因変化を検出したり、制御する考え方を転換することによって、上記課題を解決する方法に想い至った。すなわち、前記の要因変化を直接 検出または制御できなくても、溶着時間や出力等を調節することで、確実な溶着は可能な筈である。
【０００７】
そして、最終的に確実な溶着がなされた状態を何らかの方法・手段で確認し、また制御できれば、測定または制御困難な上記要因の検出は不要である。言い換えれば、要因変化に追随されるものによって、溶着時間や出力を調節することで、確実な溶着を（安定して）実現できる制御方法である。本発明は上記のような発想転換の下に、様々な方法・手段を模索することによって、なされたものである。
【０００８】
本発明者は、被溶着物は両側から金型で挟持され、その両金型はシリンダで中心（即ち、被溶着物の存在する）方向に押圧されているため、被溶着物の溶着が完了すると、前記両側の金型間の距離が変化（短くなる）することに着眼し、金型間の距離を検出する方法・手段を模索・検討した。そして、高価な検出器や大がかりな装置を使用しなくても、コンデンサー及び共振周波数の原理によって、高周波溶着処理部（高周波発振回路および高周波同調回路を含み、電源部から供給される電力を高周波エネルギーに変換し、溶着金型に伝達する部位をいう）に供給される電流値を測定することで、簡便に且つ正確に金型間の距離を検出できることを発見した。
【０００９】
即ち、本発明の第１は、高周波溶着の制御方法であって、被溶着物を挟む少なくとも２枚の（溶着）金型の間の距離の変化を、前記高周波溶着処理部に供給される電流値によって検出し、該電流（値）の検出によって、前記高周波溶着処理部に供給する電力量を制御することを特徴とする高周波溶着の制御方法である。
【００１０】
本発明（真空管式の場合）において、高周波溶着処理部に供給される電流（値）の計測する位置を図によって説明する。図８は、高周波溶着制御装置のより詳細な模式図である。この図によって、発振回路に流れるプレート電流Ａと、同調回路７に流れる高周波電流ＡHFが比例することを説明する。本例の発振器は自己発振回路のため、高周波出力の一部がグリッドコイル１５ａを通して、入力側へ加わる。これを帰還という。入力側に加わった高周波電圧は増幅され、出力側に出て、同調回路の中の金型部２で消費される。
【００１１】
この場合、同調回路７の共振周波数と発振周波数が同一になった時に、前述の帰還量は最大となり、従って、消費される電流および出力された高周波電流も最大となる。即ち、同調回路の共振周波数と発振周波数が一致したとき、グリッドへの帰還量は最大となり、同時に出力電力も最大となる。図８の各構成要素間の電流の方向を模式的に示したのが、図９であり、電流計を通る直流電流（プレート電流）は、同調回路に向かう高周波出力電力に比例することが理解される。そして、この高周波出力（電流または電力）を計測するのは、後述するように種々の問題があるため、高周波同調回路や高周波発振回路（発振器）に電流を供給する回路に電流計を設けて、電流値を計測する。また、図８に示すように発振回路を流れる電流を計測するために、電流計１０ａの代わりに、カソード１８の手前に電流計１０ｂを配置しても良い。
【００１２】
本発明でいう高周波溶着処理部とは、前述したように、電源部から供給される電力を高周波エネルギーに変換し、溶着金型に伝達する部位を言う。図で示すならば、図６や図９の２１で示される範囲のものであり、高周波発振回路２０および高周波同調回路１９を含む、高周波発振器５から金型２までの高周波溶着処理を行う部位である。
【００１３】
図８で示される高周波同調回路内に流れる電流（値）や、図６で示される発振器と各金型を連絡する高周波溶着処理部内の電流（値）を計測するのは容易ではなく、またコストが高くなるため、本発明の高周波溶着の制御方法および装置においては、高周波発振回路、発振器、または高周波同調回路に入る前の電源線９の位置に電流計を装着して、高周波溶着処理部に供給される電流（値）を計測するのが望ましい。上述の位置で電流値を計測することで、正確に（且つ安定して）安価に電流（値）を計測できる。
【００１４】
また、本発明の制御方法は上記特徴の範囲で、下記のような好ましい実施態様をとることもできる。即ち、前記検出する電流が、発振回路の（発振管の）プレートまたはカソードの少なくともいずれかに流れるものである前記の高周波溶着の制御方法である。そして、半導体を使った発振回路においては、その回路の消費する電流を検出することによて、前記高周波エネルギー量を制御するものである。
【００１６】
また、前記電流値の検出において、電流値が極大となった後の減少区域（折り返し）に溶着完了点を設定し、該溶着完了点まで溶着を継続する前記の高周波溶着の制御方法である。
【００１７】
また、前記溶着完了点の電流値を基準値として設定し、前記基準値を溶着時間（または高周波出力）の調節に利用する前記の高周波溶着の制御方法である。
【００１８】
また、被溶着物を挟む両側の金型を被溶着物方向に移動して、前記両金型間の距離が、被溶着物の挟持された幅と実質的に同じになったときを溶着開始点とし、該溶着開始点に流れる電流値を基準値として設定し、前記基準値を溶着時間の調節に利用する前記の高周波溶着の制御方法である。
【００１９】
また、前記溶着完了点の電流値を高値（ＨＩ）基準とし、前記溶着開始点の電流値を低値（ＬＯＷ）基準として設定し、両基準を溶着時間（または高周波出力）の調節に利用する前記の高周波溶着の制御方法である。
【００２０】
また、前記溶着開始点の時間値と、前記溶着完了点の時間値の差を溶着時間として検出し、該溶着時間が所定範囲外であれば、不良として検知する前記に記載の高周波溶着の制御方法である。
【００２１】
本発明の第２は、高周波溶着の処理および制御を行う装置であって、被溶着物を挟む少なくとも２枚の（溶着）金型の間の距離の変化を、高周波溶着処理部に供給される電流値によって検出し、該電流（値）の検出によって、前記高周波溶着処理部に供給する電力量を制御することを特徴とする高周波溶着の処理装置である。また、前記実施態様に記載された各種の制御方法を使用した高周波溶着処理装置である。
【００２２】
さらに、上記の高周波溶着処理装置は、下記のような好ましい実施態様をとることもできる。即ち、被溶着物の溶着によって、被溶着物を挟む２枚の（溶着）金型の間の距離が変動する際に、これらの金型の変動区域内に発振回路を流れる電流値の極大が存在するように、金型面積、金型間距離、コイルの容量、コンデンサーの容量のいずれかを調整した前記の高周波溶着処理装置である。
【００２３】
本発明の制御方法または溶着処理装置では、被溶着物を挟持している両側の金型に高周波エネルギーを加えることによって、被溶着物が溶解し、その結果、金型間の距離が変化する。大抵の場合、その距離は小さくなる。後述の式(1)、(2)で示されるように、前記距離の減少に伴って、同調回路の共振周波数が低下していく。一方、発振周波数は固定である。従って、溶着が進み、金型間距離が低下するに伴って、最初高かった共振周波数は低下し、発振周波数に近づいてくる。発振周波数と共振周波数が一致した時に回路に最大電流が流れる。その結果、回路に流れる電流は徐々に増加し、共振周波数と発振周波数が同じ値になった時に電流値は最大となる。
【００２４】
しかし、さらに金型間距離が縮まり、共振周波数が発振周波数より小さくなると、逆に電流値は低下する。そして、溶着が完了した時点以降では、金型間距離が変化しないため、電流値の変動も不変となる。本発明の制御方法または溶着処理装置において、被溶着物を挟持した金型間の距離が変化することが、溶着完了を確認する上で必須となる。従って、本発明では、溶着の進行に伴って両側の金型間の距離が縮まるような機構・手段を有するものが望ましい。例えば、各金型を両側から押圧するシリンダ（例えば、エアーシリンダや油圧シリンダ等）のような補助手段を有するものが挙げられる。
【００２５】
【発明の実施の形態】
以下、図面によって本発明の実施形態の例について、述べる。図６は高周波溶着を制御するための装置１（以下、溶着制御装置ともいう）の全体的構成の概略を示すものである。合成樹脂製の被溶着物１１を両側から挟むように、所定の間隔をあけて金型２ａ，２ｂが配置される。２つのシリンダ３ａ，３ｂによって、上下の２つの金型２ａ，２ｂが両側から被溶着物を押圧できるように、各シリンダが各金型の両側に配置される。溶着開始直前、被溶着物は両金型に当接した状態で挟まれ、シリンダによって一定の圧力を受ける。
【００２６】
下側の金型２ｂは電源供給ケーブル４によって、発振器５と連絡し、上側の金型２ａは電源供給ケーブル４によって、マッチングボックス７と連絡している。また、マッチングボックス７は電源供給ケーブル４によって、発振器５と連絡している。さらに、発振器５は回路９によって高圧電源と連絡されるが、この回路９にそこを流れる電流を計測するための電流計１０が装着されている。ここで、回路９に装着する電流計１０は特別なものでなく、ごく普通に市販されているもので良い。回路に流れる電流は、真空管式の場合、およそ０．３〜２．０アンペアであるから、その範囲の電流が計測可能なものであれば、特に限定されない。半導体式の場合は数百アンペアの電流が流れる。
【００２７】
上記の状態で、発振器５を作動して金型２ａ、２ｂに高周波エネルギーを加えると、被溶着物１１は前記高周波エネルギーによって金型に発生したジュール熱によって溶解し、また金型２ａ、２ｂはシリンダ３によって、両側から押圧されているため、被溶着物の溶解の進行に伴って、金型２ａ、２ｂ間の距離が小さくなる。そして、溶着が完了した時点で金型２ａ、２ｂ間の距離は不変となる。本発明は、コンデンサー及び共振周波数の原理によって、回路９を流れる電流値が金型２ａ、２ｂ間の距離によって影響されるのを利用したものであり、前記電流値によって金型間距離を検出するものである。電流が所定の変動を経て、所定の基準値になった時に、金型間距離が既定値になったものとして、エネルギー出力を停止するものである。
【００２８】
図９に示すように、電流値計測手段（メーター）１０と電源１７とを制御手段１４を介して連絡し、電流値が所定の変動を検出するまで、高周波溶着処理装置にエネルギー（電力）を供給し、前記変動を検出した際に出力を自動的に停止するようにしても良い。
【００２９】
【実施例】
図１は、本発明の高周波溶着の制御装置の構成をより簡易に模式的に示したものである。被溶着物１１を挟んだ両側の金型２ａ，２ｂは、コンデンサーの役割を果たしており、本制御装置はそのコンデンサーを挟んだ共振回路を含む高周波溶着処理部に供給される電流（値）を計測するものである。また、高周波発振回路は図示しないが、発振器５を有する。
【００３０】
上記装置の上下の金型がコンデンサー６の役割を果たすため、以下の機構により、金型間距離の変化を回路に流れる電流値でもって、計測することが可能となる。両側の金型の面積をＡ、金型間の距離をｌとすると、上下金型のコンデンサー容量Ｃは以下の式で示される。（εＳは の比誘電率を示す）
Ｃ=８．８５５×１０−１２εＳＡ／ｌ・・・… (1)
【００３１】
そして、上下金型および素材の誘電率により、コンデンサー６が形成され、金型へ供給の電線（銅板）によって、コイルが形成される。従って、前記のコイルや金型によって、 に固有の共振周波数ｆが決まる。
ｆ= １／２π√(Ｌ・Ｃ) ・・・… (2)
〔上式において、Ｌはコイルの容量（Ｈ），Ｃ：コンデンサー容量（Ｆ）〕
従って、図５に示されるように、金型間の距離が広い場合（溶着開始点）には、共振周波数ｆが高く、溶着によって金型間距離が狭くなるにつれて、共振周波数ｆはＰ→Ｑ→Ｒと徐々に低くなる。右下がりの一点鎖線のグラフが共振周波数の変化を示す。
【００３２】
発振周波数は、金型間距離によって影響されずに一定であり、距離の減少によって共振周波数が低下するため、発振周波数と共振周波数の値は近づいていく。そして、発振周波数と共振周波数とが一致した時に、この回路には最大の電流が流れる。
【００３３】
図５に示すように、被溶着物が両側の金型に当接し、金型間距離が被溶着物の挟持された幅と実質的に同じになったときを溶着開始点（図５のＳ点）とする。その時点で流れる電流値をＬ（この値を、低い方の設定基準値ということでＬＯＷ基準ともいう）として、設定する。この時の共振周波数はＰである。金型間距離が短くなるにつれて、回路に流れる電流値は徐々に大きくなり、上述の両周波数が一致した時点（図５のＭ点）で最大の電流が流れるが、それ以上時間が経過すると、逆に電流値は低下していく。
【００３４】
また、金型間距離の変化が小さくなるにつれて、共振周波数の低下および電流値の低下も収束してくる。電流値が極大を示した後に、既述した電流値の収束によって変曲点が認められるが、この時点を溶着完了点（図５のＦ点）として、この時に流れる電流値をＨ（この値を、高い方の設定基準値ということでＨＩ基準ともいう）として、設定する。この時の共振周波数はＲである。
【００３５】
上記に示したように、所定の形状・寸法の金型、被溶着物でもって、予め基準値となる電流値のＬＯＷ基準、ＨＩ基準を設定しておく。そして、溶着が行われる際に、メータ１０の目盛り１３に、ＬＯＷ基準：ＬとＨＩ基準：ＨのIndexを付けておき（図２参照）、この２点間の電流値の推移を確認しながら、高周波出力のＯＮ、ＯＦＦを制御すれば良い。
【００３６】
簡便には、電流値が極大を示した後の折り返しで、且つＨＩ基準を通過した時点で高周波出力を停止するようにしても良い。但し、金型への被溶着物の装着忘れ、金型からの被溶着物の脱落等のようなケースも起こり得るので、ＬＯＷ基準を規定しておき、溶着中の電流値の変動を確認することによって、上記トラブルを未然に防止しても良い。また、ＬＯＷ基準から（折り返しの）ＨＩ基準までかかる時間を計測し、その要した時間；溶着時間が所定範囲外の場合は不良として、検知されるようにしても良い。
【００３７】
図３のグラフは、従来の溶着時間のみで高周波溶着を制御していたときの失敗例と、その際に本発明の方法・装置でどのように電流値が検出され、溶着が制御できるかを示すものである。図３には成功例とともに、被溶着物の素材、形状、寸法によって、適当な溶着時間が設定できないため、溶着過多または溶着不足になる場合を示している。即ち、溶着過多（一点鎖線）の場合、溶着時間Ｔ２以前に既に溶着が完了しているにも関わらず、被溶着物に余計な高周波出力を加えている。これは、エネルギーの無駄となるだけでなく、被溶着物にダメージを与えることになるので、好ましくない。
【００３８】
逆に溶着不足（破線）の場合、溶着時間Ｔ２では未だ溶着が完了していないにも関わらず、高周波出力を停止しているので、不充分な溶着となっている。このとき、本発明の制御方法または装置によって、それぞれのケースにおいて、過不足無く溶着させることができる。先ず回路に流れる最大（極大）電流値以下のＨＩ基準を設定し、回路内を流れる電流が極大を示した後、ＨＩ基準を通過したとき（折り返し点）に高周波出力が停止するように、溶着完了点を規定しておく。このように溶着完了点を設定することで、それぞれのケースで最適な溶着時間を調整することができる。結果的に、図３の溶着過多の場合には、溶着時間Ｔ１が、溶着不足の場合には、溶着時間Ｔ３が割当てられることになる。
【００３９】
或いはＨＩ基準として、電流値の変動が収束する変曲点を指定しても良い。そうすることで、より強力で確実な溶着が得られる。さらに前述したように、ＬＯＷ基準を規定し、それを通過することで溶着の開始が確認できるので、未然に被溶着物の未装着や抜去などのトラブルを防止することもできる。
【００４０】
先に示した例と重複するが、溶着時間の異なる被溶着物を本発明の制御方法、装置によって、高周波出力の時間を調整する例をグラフによって示したものが図４である。事前に、溶着完了点が最大電流値の以降になるように金型間距離や金型面積、コイルの容量、コンデンサーの容量、等を調整しておく。同様に、金型が被溶着物に当接し、高周波の出力開始となる時点での電流値（ＬＯＷ基準）：Ｌと、最大電流値以降の変曲点となる箇所の電流値（ＨＩ基準）：Ｈを設定しておく。
【００４１】
次に、最大電流前のＨＩ基準を通過した場合には高周波出力を継続し、前述のＨＩ基準を通過した場合に、出力を停止するように溶着完了点を設定する。図４に示すように、３種類の被溶着物Ａ，Ｂ，Ｃは溶着開始点は同じＴＳであるが、溶着完了点はそれぞれＴＦ’、ＴＦ''、ＴＦ'''と異なり、それぞれ最適な溶着時間ＴＡ、ＴＢ、ＴＣが割り当てられている。
【００４２】
本発明の制御装置では、上述したように高周波溶着処理部に供給される電流（値）を計測し、該電流値の変化によって、高周波出力（高周波溶着処理部に供給する電力量）を自動的にオフする、または溶着工程（溶着時間）を自動的に中止するように、中間制御手段１４、および電流計や高周波出力手段と前記中間制御手段を連絡する連絡回路２２を設けても良い。
【００４３】
また、従来は発振管の能力の低下を予測する手段が無かったため、使用時間によって発振管の寿命管理を行っていたが、非常に不正確なものであった。本発明の高周波溶着の制御方法や装置によれば、以下に記載する方法によって、発振管の性能を正確に把握することができる。即ち、発振管の能力低下が起こると、溶着時間が自動的に長くなる。溶着時間とは、前述の溶着開始点から溶着完了点までに要する時間であり、その時間に対して予め許容できる値を設定しておくのである。その設定時間を超えたら、発振管に異常が発生したか、または自然消耗による能力低下と判断して、発振管を取り換えるようにするのである。
【００４４】
溶着時間の増大には、エミッションの低下（カソード電流が流れなくなる）による場合と、グリッドそのものの消耗によって、プレート電流は流れるが、高周波出力が低下する場合があり、その区別もプレート電流と高周波電力（同調回路のＡHFの計測によって、定量可能）の両者の計測によって、可能となる。
【００４５】
【発明の効果】
本発明によって、以下の様々な効果が得られる。
１．金型や被溶着物の温度や形状、高周波溶着処理装置の状態に影響されずに、確実な溶着を行うことができる。
２．被溶着物が完全に溶着されるまで、エネルギーの供給を行うので、溶着不足や過溶着が防止できる。
３．機械的なトラブル（例えば、金型の動作不良によって、被溶着物が挟持されてない等の）が発生した場合でも、そのトラブルを検出でき、不良品を除外することができる。
４．既述したように、溶着時間や（発振回路に流れる）溶着電流の変化によって、発振管の状態、寿命が判断できる。
５．機械的な引張り等の検品をすることなく、他のパラメータによる溶着保証が可能となる。
【図面の簡単な説明】
【図１】本発明の溶着制御装置の実施例を説明するために、より簡易的に示した模式図である。
【図２】本発明に利用する電流計（メーター）の１つの実施態様を示す概略図である。
【図３】従来の溶着処理装置によって、溶着を行った場合の失敗例および成功例における各電流値の経時変化を模式的に示すグラフである。
【図４】本発明の高周波溶着制御装置を使用して、溶着を制御したそれぞれの被溶着物における各電流値の経時変化を模式的に示すグラフである。
【図５】金型間距離の変化によって、影響を受ける電流値および共振周波数の各変動を模式的に示すグラフである。
【図６】本発明の溶着制御装置の、一つの実施例の全体的な構成を示した概略図である。
【図７】従来の高周波溶着処理装置の一例を示す概略図である。
【図８】本発明の高周波溶着制御装置のより詳細な構成・配置を示す模式図である。
【図９】図８の各構成要素間の電流の方向を模式的に示した概略図である。
【符号の説明】
１．溶着制御装置
２．金型（金型部）
２ａ．上部金型
２ｂ．下部金型
３．シリンダ
３ａ．シリンダ（上）
３ｂ．シリンダ（下）
４．電力供給ケーブル
５．発振器
６．コンデンサ
７．マッチングボックス
９．電源線
１０．メーター（電流計）
１１．被溶着物
１２．電力供給ケーブル
１２A．電力供給ケーブル（高圧側）
１２B．電力供給ケーブル（グランド側）
１３．目盛り
１４．（中間）制御手段
１５．同調コイル
１５ａ．コイル（出力同調）
１５ｂ．グリッドコイル（入力同調）
１６．発振管
１７．電源部
１８．アース
１９．高周波同調回路
２０．高周波発振回路
２１．高周波溶着処理部
２２．連絡回路
ＡHF．高周波電流
Ａ1．プレート電流
Ａ2．カソード電流
Ｈ．ＨＩ基準（高値側の電流値基準）
Ｌ．ＬＯＷ基準（低値側の電流値基準）
Ｔ．従来の溶着時間（被溶着物に依らず、一定）
Ｔ０．溶着開始点
Ｔ１．（溶着過多の被溶着物の）溶着完了点
Ｔ２．（成功例の）溶着完了点
Ｔ３．（溶着不足の被溶着物の）溶着完了点
ＴＳ．溶着開始点
ＴＦ’．（被溶着物Ａ）の溶着完了点
ＴＦ ''．（被溶着物Ｂ）の溶着完了点
ＴＦ '''．（被溶着物Ｃ）の溶着完了点
ＴＡ．（被溶着物Ａ）に最適な溶着時間
ＴＢ．（被溶着物Ｂ）に最適な溶着時間
ＴＣ．（被溶着物Ｃ）に最適な溶着時間
Ｓ．溶着開始点
Ｍ．回路に最大電流が流れる時点
Ｆ．溶着完了点
Ｐ．溶着開始時における共振周波数
Ｑ．回路に最大電流が流れる時の共振周波数
Ｒ．溶着完了時における共振周波数[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control method in high-frequency welding, and more particularly to a high-frequency welding control mechanism in which high-frequency welding processing is continued until welding is completed, and the processing is immediately stopped when welding is completed.
[0002]
[Prior art]
In conventional high-frequency welding, since welding control is managed by time and output, depending on the material and shape of the object to be welded and the state of the welding equipment, it may become over-welded or insufficiently welded, thus occurring Defects significantly reduced production efficiency. Depending on the application and situation, if a defective product cannot be detected in advance, it can lead to a major accident.
[0003]
As shown in FIG. 7, in conventional high-frequency welding, a part to be welded is melted and bonded by sandwiching the object to be welded between upper and lower molds and applying high-frequency energy to the mold. It was. The control at that time is only the increase / decrease of the welding time, and the operator operates it by the can and experience while considering the material of the object to be welded and the state of the apparatus. For this reason, a skilled engineer is required, and it has been very difficult for an expert to reduce the defective product generation rate.
[0004]
In order to improve or stabilize the welded state, the present inventor has attempted control by various methods. For example, in order to adjust the material temperature (of the material to be welded), we tried to attach a heating unit to the material to be welded, or tried to adjust the electrode plate to control the mold temperature or improve the high-frequency tuning circuit. None of these were fundamental measures for poor welding. The cause is thought to be because there are many factors that cause poor welding, and the control means cannot keep up with changes in those factors. However, it has been very difficult to detect and control all these factor changes.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to ensure welding even when various factors change that cause poor welding. That is, it is to provide a control method for high-frequency welding that is controlled so as to always perform reliable welding without being affected by changes in factors such as material temperature, mold temperature, high-frequency tuning circuit, and the like. It is providing the high frequency welding processing apparatus which welds using this.
[0006]
[Means for Solving the Problems]
The present inventor has come up with a method for solving the above-mentioned problems by changing the way of thinking to detect or control many of the above-mentioned factor changes. That is, even if the above factor change cannot be directly detected or controlled, it is possible to perform reliable welding by adjusting the welding time, output, and the like.
[0007]
Then, if it is possible to confirm and control the state where the reliable welding has been finally achieved by some method or means, it is not necessary to detect the above factors that are difficult to measure or control. In other words, it is a control method that can realize reliable welding (stable) by adjusting the welding time and output according to what follows the factor change. The present invention has been made by searching for various methods and means under the above-mentioned concept change.
[0008]
The present inventor has completed the welding of the object to be welded because the object to be welded is clamped by the molds from both sides, and both the molds are pressed in the center (that is, the existence of the object to be welded) by the cylinder. Then, focusing on the fact that the distance between the molds on both sides changes (becomes shorter), we have sought and studied methods and means for detecting the distance between the molds. Even without using an expensive detector or a large-scale device, the high-frequency welding processing unit (including the high-frequency oscillation circuit and the high-frequency tuning circuit, and the power supplied from the power supply unit can be It was discovered that the distance between the molds can be detected easily and accurately by measuring the value of the current supplied to the welding mold.
[0009]
In other words, the first aspect of the present invention is a method for controlling high-frequency welding, in which a change in the distance between at least two (welding) molds sandwiching an object to be welded is a current supplied to the high-frequency welding processing section. It is a control method for high frequency welding characterized by detecting by value and controlling the amount of power supplied to the high frequency welding processing section by detecting the current (value).
[0010]
In the present invention (in the case of a vacuum tube type), the position where the current (value) supplied to the high-frequency welding processing unit is measured will be described with reference to the drawings. FIG. 8 is a more detailed schematic diagram of the high-frequency welding control apparatus. This figure explains that the plate current A flowing through the oscillation circuit and the high frequency current AHF flowing through the tuning circuit 7 are proportional. Since the oscillator of this example is a self-oscillation circuit, a part of the high-frequency output is applied to the input side through the grid coil 15a. This is called return. The high frequency voltage applied to the input side is amplified, exits to the output side, and is consumed by the mold part 2 in the tuning circuit.
[0011]
In this case, when the resonance frequency and the oscillation frequency of the tuning circuit 7 are the same, the aforementioned feedback amount is maximized, so that the consumed current and the output high-frequency current are also maximized. That is, when the resonance frequency and the oscillation frequency of the tuning circuit coincide with each other, the feedback amount to the grid is maximized, and the output power is also maximized. FIG. 9 schematically shows the direction of current between each component in FIG. 8, and it is understood that the direct current (plate current) passing through the ammeter is proportional to the high-frequency output power toward the tuning circuit. Is done. And measuring this high frequency output (current or power) has various problems as will be described later, so an ammeter is provided in a circuit that supplies current to a high frequency tuning circuit or a high frequency oscillation circuit (oscillator), Measure the current value. Further, as shown in FIG. 8, in order to measure the current flowing through the oscillation circuit, the ammeter 10b may be arranged in front of the cathode 18 instead of the ammeter 10a.
[0012]
As described above, the high-frequency welding processing section in the present invention refers to a portion that converts electric power supplied from the power supply section into high-frequency energy and transmits it to the welding mold. If it shows in a figure, it is the thing shown in 21 of FIG.6 and FIG.9, and is a site | part which performs the high frequency welding process from the high frequency oscillator 5 to the metal mold | die 2 including the high frequency oscillation circuit 20 and the high frequency tuning circuit 19. is there.
[0013]
It is not easy to measure the current (value) flowing in the high-frequency tuning circuit shown in FIG. 8 and the current (value) in the high-frequency welding processing section connecting the oscillator and each mold shown in FIG. Therefore, in the high frequency welding control method and apparatus of the present invention, an ammeter is attached to the position of the power line 9 before entering the high frequency oscillation circuit, the oscillator, or the high frequency tuning circuit, and the high frequency welding processing section is installed. It is desirable to measure the current (value) supplied. By measuring the current value at the above position, the current (value) can be measured accurately (and stably) at low cost.
[0014]
Further, the control method of the present invention can take the following preferred embodiments within the range of the above characteristics. That is, in the above-described high frequency welding control method, the detected current flows through at least one of a plate (of the oscillation tube) and a cathode of the oscillation circuit. In an oscillation circuit using a semiconductor, the amount of high-frequency energy is controlled by detecting a current consumed by the circuit.
[0016]
Further, in the detection of the current value, the high-frequency welding control method described above, wherein a welding completion point is set in a decrease area (turnback) after the current value becomes maximum, and welding is continued to the welding completion point.
[0017]
Further, in the above high frequency welding control method, the current value at the welding completion point is set as a reference value, and the reference value is used for adjusting the welding time (or high frequency output).
[0018]
Also, when the metal molds on both sides of the object to be welded are moved in the direction of the object to be welded, the welding starts when the distance between the two molds becomes substantially the same as the width of the object to be welded. In this high-frequency welding control method, the current value flowing through the welding start point is set as a reference value, and the reference value is used for adjusting the welding time.
[0019]
Also, the current value at the welding completion point is set as a high value (HI) standard, the current value at the welding start point is set as a low value (LOW) standard, and both standards are used for adjusting the welding time (or high frequency output). This is a method for controlling the high frequency welding.
[0020]
The high frequency welding control as described above, wherein a difference between a time value of the welding start point and a time value of the welding completion point is detected as a welding time, and if the welding time is out of a predetermined range, it is detected as defective. Is the method.
[0021]
A second aspect of the present invention is an apparatus for performing processing and control of high-frequency welding, and a change in the distance between at least two (welding) molds sandwiching an object to be welded is supplied to the high-frequency welding processing unit. A high-frequency welding processing apparatus that detects a current value and controls an amount of electric power supplied to the high-frequency welding processing unit by detecting the current (value). Moreover, it is a high frequency welding processing apparatus using the various control methods described in the embodiment.
[0022]
Furthermore, the above-described high-frequency welding processing apparatus can take the following preferred embodiments. That is, when the distance between two (welding) molds sandwiching the object to be welded varies due to the welding of the object to be welded, the maximum value of the current flowing through the oscillation circuit in the variation area of these molds is increased. The high-frequency welding apparatus according to claim 1, wherein any one of a mold area, a distance between molds, a coil capacity, and a capacitor capacity is adjusted so as to exist.
[0023]
In the control method or the welding processing apparatus of the present invention, the welding object is melted by applying high-frequency energy to the molds on both sides sandwiching the welding object, and as a result, the distance between the molds changes. In most cases, the distance is small. As shown in equations (1) and (2) described later, the resonance frequency of the tuning circuit decreases as the distance decreases. On the other hand, the oscillation frequency is fixed. Accordingly, as the welding progresses and the distance between the molds decreases, the resonance frequency that was initially high decreases and approaches the oscillation frequency. The maximum current flows in the circuit when the oscillation frequency and the resonance frequency match. As a result, the current flowing in the circuit gradually increases, and the current value becomes maximum when the resonance frequency and the oscillation frequency become the same value.
[0024]
However, when the distance between the molds is further shortened and the resonance frequency is lower than the oscillation frequency, the current value is decreased. Since the distance between the molds does not change after the completion of welding, the current value does not change. In the control method or the welding processing apparatus of the present invention, it is essential to confirm the completion of welding that the distance between the molds sandwiching the object to be welded is changed. Therefore, in the present invention, it is desirable to have a mechanism / means for reducing the distance between the molds on both sides as the welding proceeds. For example, one having auxiliary means such as a cylinder (for example, an air cylinder or a hydraulic cylinder) that presses each mold from both sides can be mentioned.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, examples of embodiments of the present invention will be described with reference to the drawings. FIG. 6 shows an outline of the overall configuration of an apparatus 1 (hereinafter also referred to as a welding control apparatus) for controlling high-frequency welding. The molds 2a and 2b are arranged at a predetermined interval so as to sandwich the welded material 11 made of synthetic resin from both sides. The cylinders are arranged on both sides of each mold so that the two upper and lower molds 2a and 2b can press the object to be welded from both sides by the two cylinders 3a and 3b. Immediately before the start of welding, the object to be welded is sandwiched in contact with both molds and receives a certain pressure by the cylinder.
[0026]
The lower mold 2 b communicates with the oscillator 5 through a power supply cable 4, and the upper mold 2 a communicates with the matching box 7 through the power supply cable 4. The matching box 7 communicates with the oscillator 5 through the power supply cable 4. Further, the oscillator 5 is connected to a high-voltage power supply by a circuit 9, and an ammeter 10 for measuring a current flowing therethrough is attached to the circuit 9. Here, the ammeter 10 attached to the circuit 9 is not special and may be a commercially available one. In the case of a vacuum tube type, the current flowing through the circuit is about 0.3 to 2.0 amperes, so that it is not particularly limited as long as the current in the range can be measured. In the case of a semiconductor type, a current of several hundred amperes flows.
[0027]
In the above state, when the oscillator 5 is operated and high frequency energy is applied to the molds 2a and 2b , the welding object 11 is melted by the Joule heat generated in the mold by the high frequency energy, and the molds 2a and 2b are Since the cylinder 3 is pressed from both sides , the distance between the molds 2a and 2b becomes smaller as the welding object is dissolved. When the welding is completed , the distance between the molds 2a and 2b remains unchanged . The present invention utilizes the fact that the current value flowing through the circuit 9 is affected by the distance between the molds 2a and 2b based on the principle of the capacitor and the resonance frequency, and the distance between the molds is detected by the current value. Is. When the current reaches a predetermined reference value through a predetermined fluctuation, the energy output is stopped assuming that the distance between the molds is a predetermined value.
[0028]
As shown in FIG. 9, the current value measuring means (meter) 10 and the power source 17 are connected via the control means 14, and energy (electric power) is supplied to the high-frequency welding processing apparatus until the current value detects a predetermined fluctuation. The output may be automatically stopped when the fluctuation is detected.
[0029]
【Example】
FIG. 1 schematically shows the configuration of a control apparatus for high-frequency welding according to the present invention more simply. The molds 2a and 2b on both sides of the object to be welded 11 play the role of a capacitor, and this control device measures the current (value) supplied to the high-frequency welding processing unit including the resonance circuit that sandwiches the capacitor. To do. Further, although not shown, the high-frequency oscillation circuit has an oscillator 5.
[0030]
Since the upper and lower molds of the above apparatus serve as the condenser 6, it is possible to measure the change in the distance between the molds with the current value flowing through the circuit by the following mechanism. When the area of the molds on both sides is A and the distance between the molds is 1, the capacitor capacity C of the upper and lower molds is expressed by the following formula. (Ε S is the relative dielectric constant of)
C = 8.855 × 10 −12 ε S A / l (1)
[0031]
And the capacitor | condenser 6 is formed with the dielectric constant of an up-and-down metal mold | die and a raw material, and a coil is formed with the electric wire (copper board) supplied to a metal mold | die. Therefore, the resonance frequency f unique to is determined by the coil and the mold.
f = 1 / 2π√ (L · C) (2)
[In the above formula, L is the coil capacity (H), C: capacitor capacity (F)]
Therefore, as shown in FIG. 5, when the distance between the molds is large (welding start point), the resonance frequency f is high, and as the distance between the molds becomes narrow due to welding, the resonance frequency f becomes P → Q. → R gradually decreases. A graph of a one-dot chain line descending to the right indicates a change in the resonance frequency.
[0032]
The oscillation frequency is constant without being influenced by the distance between the molds, and the resonance frequency is lowered by the decrease in the distance, so that the values of the oscillation frequency and the resonance frequency are close to each other. When the oscillation frequency matches the resonance frequency, the maximum current flows through this circuit.
[0033]
As shown in FIG. 5, the welding start point (S in FIG. 5) is when the object to be welded comes into contact with the molds on both sides and the distance between the molds becomes substantially the same as the sandwiched width of the object to be welded. Point). The value of the current flowing at that time is set as L (this value is also referred to as the LOW reference because it is the lower setting reference value). The resonance frequency at this time is P. As the distance between the molds becomes shorter, the value of the current flowing in the circuit gradually increases, and the maximum current flows when the above-mentioned two frequencies coincide (point M in FIG. 5). Conversely, the current value decreases.
[0034]
Further, as the change in the distance between the molds becomes smaller, the decrease in the resonance frequency and the decrease in the current value also converge. After the current value shows the maximum, an inflection point is recognized due to the convergence of the current value described above, and this time is taken as a welding completion point (point F in FIG. 5), and the current value flowing at this time is H (this value). Is set as a higher setting reference value, which is also referred to as an HI reference). The resonance frequency at this time is R.
[0035]
As described above, the LOW standard and the HI standard of the current value serving as the reference value are set in advance with a mold and a welded object having a predetermined shape and size. Then, when welding is performed, an index of LOW standard: L and HI standard: H is attached to the scale 13 of the meter 10 (see FIG. 2), and the transition of the current value between these two points is confirmed. It is sufficient to control ON / OFF of the high frequency output.
[0036]
Conveniently, by the return after the current value shows a maximum, and may be stopped a high frequency output at the time of passing through the HI reference. However, cases such as forgetting to attach the object to be welded to the mold or dropping of the object to be welded from the mold may occur. Therefore, the LOW standard is specified and the fluctuation of the current value during welding is confirmed. Therefore, the above trouble may be prevented beforehand. Alternatively, the time taken from the LOW reference to the (turned back) HI reference may be measured, and the required time; if the welding time is outside the predetermined range, it may be detected as defective.
[0037]
The graph of FIG. 3 shows a failure example when high-frequency welding is controlled only by the conventional welding time, and how the current value is detected and the welding can be controlled by the method and apparatus of the present invention at that time. It is shown. FIG. 3 shows a case where there is excessive welding or insufficient welding because an appropriate welding time cannot be set depending on the material, shape and dimensions of the object to be welded together with a successful example. That is, in the case of welding excessive (dashed line), despite the already welded to the welding time T 2 previously has been completed, and added extra high-frequency output to be welded object. This is not preferable because it not only wastes energy but also damages the object to be welded.
[0038]
Conversely when welding shortage (dashed line), despite still in the welding time T 2 welding is not completed, since the stop frequency output, has become insufficient welding. At this time, welding can be performed without excess or deficiency in each case by the control method or apparatus of the present invention. First, set the HI reference below the maximum (maximum) current value flowing in the circuit, and after the current flowing through the circuit shows the maximum, welding is performed so that the high-frequency output stops when the HI reference is passed (turnback point) Define the completion point. By setting the welding completion point in this way, the optimum welding time can be adjusted in each case. Consequently, in the case of welding plethora of Figure 3, the welding time T 1 is, in the case of welding shortage would have welding time T 3 is assigned.
[0039]
Alternatively, as an HI reference, an inflection point at which the fluctuation of the current value converges may be designated. By doing so, stronger and more reliable welding can be obtained. Further, as described above, since the start of welding can be confirmed by defining the LOW standard and passing through it, troubles such as unloading or removal of the object to be welded can be prevented.
[0040]
Although overlapping with the example shown above, FIG. 4 shows a graph showing an example of adjusting the time of high frequency output by using the control method and apparatus of the present invention for an object to be welded having a different welding time. In advance, the distance between the molds, the mold area, the coil capacity, the capacitor capacity, and the like are adjusted so that the welding completion point is after the maximum current value. Similarly, the current value (LOW standard) at the time when the mold comes into contact with the object to be welded and the high frequency output starts (LOW standard): L and the current value at the point of inflection after the maximum current value (HI standard) : Set H.
[0041]
Next, the high frequency output is continued when the HI reference before the maximum current is passed, and the welding completion point is set so that the output is stopped when the HI reference is passed. As shown in FIG. 4, the three welding objects A, B, and C have the same welding start point, but the welding completion points are different from TF ′, TF ″, and TF ′ ″, respectively. Various welding times TA, TB and TC are assigned.
[0042]
In the control device of the present invention, as described above, the current (value) supplied to the high-frequency welding processing unit is measured, and the high-frequency output (the amount of power supplied to the high-frequency welding processing unit) is automatically determined according to the change in the current value. The intermediate control means 14 and a communication circuit 22 that communicates the ammeter or the high-frequency output means with the intermediate control means may be provided so that the welding process (welding time) is automatically stopped.
[0043]
Conventionally, since there has been no means for predicting a decrease in the capacity of the oscillation tube, the life of the oscillation tube has been managed according to the usage time, but this is very inaccurate. According to the high frequency welding control method and apparatus of the present invention, the performance of the oscillation tube can be accurately grasped by the method described below. That is, when the capacity of the oscillation tube is reduced, the welding time is automatically increased. The welding time is a time required from the above-described welding start point to the welding completion point, and an allowable value is set in advance for the time. When the set time is exceeded, it is determined that an abnormality has occurred in the oscillation tube or that the capacity has been reduced due to natural consumption, and the oscillation tube is replaced.
[0044]
The increase in the welding time is due to the decrease in emissions (cathode current stops flowing) and the plate current flows due to the consumption of the grid itself, but the high-frequency output may decrease. The distinction is also made between plate current and high-frequency power. It is possible by measuring both of them (which can be quantified by measuring the AHF of the tuning circuit).
[0045]
【The invention's effect】
The following various effects can be obtained by the present invention.
1. Reliable welding can be performed without being affected by the temperature and shape of the mold and the object to be welded and the state of the high-frequency welding processing apparatus.
2. Since energy is supplied until the object to be welded is completely welded, insufficient welding and over-welding can be prevented.
3. Even when a mechanical trouble (for example, the object to be welded is not pinched due to a malfunction of the mold) occurs, the trouble can be detected and defective products can be excluded.
4). As described above, the state and life of the oscillation tube can be determined from the welding time and the change in the welding current (flowing through the oscillation circuit).
5. It is possible to guarantee welding with other parameters without performing inspection such as mechanical tension.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic diagram more simply shown for explaining an embodiment of a welding control apparatus of the present invention.
FIG. 2 is a schematic diagram illustrating one embodiment of an ammeter utilized in the present invention.
FIG. 3 is a graph schematically showing changes with time in current values in a failure example and a success example when welding is performed by a conventional welding processing apparatus.
FIG. 4 is a graph schematically showing a change with time of each current value in each of the objects to be welded whose welding is controlled using the high-frequency welding control apparatus of the present invention.
FIG. 5 is a graph schematically showing fluctuations in current value and resonance frequency that are affected by changes in the distance between molds;
FIG. 6 is a schematic view showing the overall configuration of one embodiment of the welding control apparatus of the present invention.
FIG. 7 is a schematic view showing an example of a conventional high-frequency welding processing apparatus.
FIG. 8 is a schematic diagram showing a more detailed configuration / arrangement of the high-frequency welding control apparatus of the present invention.
9 is a schematic diagram schematically showing the direction of current between the components shown in FIG.
[Explanation of symbols]
1. 1. Welding control device Mold (mold part)
2a. Upper mold 2b. Lower mold 3. Cylinder 3a. Cylinder (top)
3b. Cylinder (bottom)
4). 4. Power supply cable Oscillator 6. Capacitor 7. 8. Matching box Power line 10. Meter (Ammeter)
11. To-be-welded object 12. Power supply cable 12A. Power supply cable (high voltage side)
12B. Power supply cable (ground side)
13. Scale 14 (Intermediate) control means 15. Tuning coil 15a. Coil (Output tuning)
15b. Grid coil (input tuning)
16. Oscillation tube 17. Power supply 18. Earth 19. High frequency tuning circuit 20. High-frequency oscillation circuit 21. High-frequency welding processing section 22. Communication circuit AHF. High-frequency current A 1 . Plate current A 2 . Cathode current H.P. HI standard (high value side current value standard)
L. LOW standard (low value side current value standard)
T.A. Conventional welding time (constant regardless of the workpiece)
T 0 . Welding start point T 1 . Welding completion point T 2 (of the object to be welded with excessive welding) (Success example) welding completion point T 3 . The welding completion point T S. Welding start point T F ′ . (Finished material A) welding completion point T F ″ . (Finished material B) welding completion point T F ′ ″ . The welding completion point T A. Optimum welding time (the weld deposits A) T B. The optimum welding time T C. Optimum welding time for (to-be-welded object C) Welding start point When the maximum current flows in the circuit Welding completion point Resonance frequency Q. at the start of welding The resonance frequency R.D. Resonance frequency at the completion of welding

Claims (9)

電源部（Ａ）、高周波発振回路、高周波同調回路、及び合成樹脂製の被溶着物（以下、被溶着物と言う）を挟持可能で、かつ前記高周波発振回路によって付加される高周波エネルギーによってジュール熱を発生して前記被溶着物を溶着可能な２個の金型を有する高周波溶着処理部（Ｂ）、前記２個の金型に装着され、かつ前記被溶着物の溶着の進行に伴って該金型間の距離を縮めるように該金型をその中心方向に押圧する押圧手段（Ｃ）及び前記高周波溶着処理部（Ｂ）に供給される電流値を測定する電流計（Ｄ）を有し、かつ該電流計（Ｄ）によって測定された電流値によって金型間距離を検出し、この検出結果に基づいて高周波溶着処理部（Ｂ）に供給する電力（以下、エネルギーと言う）を制御するものであることを特徴とする被溶着物の高周波溶着装置。A power source (A), a high-frequency oscillation circuit, a high-frequency tuning circuit, and a synthetic resin welding object (hereinafter referred to as a welding object) can be sandwiched, and Joule heat is generated by the high-frequency energy added by the high-frequency oscillation circuit. The high frequency welding process part (B) which has two metal mold | die which can generate | occur | produce and weld the said to-be-welded object, It is mounted | worn with the said 2 metal mold | die, and said welding object progresses as the welding progresses A pressing means (C) for pressing the molds in the center direction so as to reduce the distance between the molds, and an ammeter (D) for measuring a current value supplied to the high-frequency welding processing section (B) The distance between the molds is detected based on the current value measured by the ammeter (D), and the electric power (hereinafter referred to as energy) supplied to the high-frequency welding processing part (B) is controlled based on the detection result. Welding characterized by being High-frequency welding device. 前記電流計（Ｄ）が電源部（Ａ）と前記高周波溶着処理部（Ｂ）を連結する電源線（Ｅ）に装着され、かつ該電源部（Ａ）と前記高周波溶着処理部（Ｂ）の間に配置されたものである請求項１記載の被溶着物の高周波溶着装置。 The ammeter (D) is attached to a power supply line (E) connecting the power supply unit (A) and the high frequency welding processing unit (B), and the power supply unit (A) and the high frequency welding processing unit (B) The high-frequency welding apparatus for welding objects according to claim 1, which is disposed between the two . 前記電流計（Ｄ）と電源部（Ａ）が制御手段（Ｆ）を介して連絡され、該制御手段（Ｆ）が前記電流計（Ｄ）によって電流値が所定の電流値に変動する迄、高周波溶着処理部（Ｂ）にエネルギーを供給し、所定の電流値が検出されるとエネルギーの供給を自動的に停止するように制御されるものである請求項２記載の被溶着物の高周波溶着装置。 The ammeter (D) and the power supply unit (A) are connected via the control means (F), and until the control means (F) changes the current value to a predetermined current value by the ammeter (D), The high-frequency welding of the object to be welded according to claim 2, wherein energy is supplied to the high-frequency welding processing section (B) and the supply of energy is automatically stopped when a predetermined current value is detected. Equipment . 前記押圧手段（Ｃ）が２個の金型に装着されたシリンダである請求項１〜３のいずれかに記載の被溶着物の高周波溶着装置。 The high-frequency welding apparatus for welding objects according to any one of claims 1 to 3, wherein the pressing means (C) is a cylinder mounted on two molds . 請求項１〜４のいずれかに記載の被溶着物の高周波溶着装置を使用して合成樹脂製の被溶着物を高周波溶着する方法において、電流計（Ｄ）によって測定された電流値によって金型間距離を検出し、この検出結果に基づいて高周波溶着処理部（Ｂ）に供給するエネルギーを制御することを特徴とする被溶着物の高周波溶着方法。 In the method of carrying out the high frequency welding of the welding thing made from a synthetic resin using the high frequency welding apparatus of the welding thing in any one of Claims 1-4, a metal mold | die with the electric current value measured with the ammeter (D) A high-frequency welding method for an object to be welded, which detects an inter-space and controls energy supplied to the high-frequency welding processing section (B) based on the detection result . 電流値が所定の基準値となった時に、金型間距離が規定値になったものとして、エネルギー出力を停止するものである請求項５に記載の被溶着物の高周波溶着方法。 6. The high-frequency welding method for an object to be welded according to claim 5, wherein when the current value becomes a predetermined reference value, the energy output is stopped assuming that the distance between the molds becomes a specified value . 前記押圧手段（Ｃ）によって金型を被溶着物方向に移動させ、該金型間の距離が該溶着物の幅と実質的に同じになったときを溶着開始点とし、該開始点で流れる電流の電流値を電流計（Ｄ）によって測定した電流値をＬＯＷ基準として設定し、このＬＯＷ基準を確認することにより金型への被溶着物の装着忘れあるいは金型からの被溶着物の脱落を検知することを特徴とする請求項５記載の被溶着物の高周波溶着方法。 The mold is moved in the direction of the object to be welded by the pressing means (C), and when the distance between the molds becomes substantially the same as the width of the welded object, the welding start point is taken and flows at the start point. Set the current value of the current measured by the ammeter (D) as the LOW standard, and check the LOW standard to forget to attach the object to the mold or drop off the object from the mold. 6. The method for high-frequency welding of an object to be welded according to claim 5, wherein: 電流計（Ｄ）によって測定した電流が極大電流値が極大値を示した後に減少に転じて、該減少に転じた電流値の減少が収束した時点を溶着完了点とし、該溶着完了点において測定される電流値をＨＩ基準として設定し、このＨＩ基準を通過した時点でエネルギー出力を停止するものであることを特徴とする請求項５記載の被溶着物の高周波溶着方法。 The current measured by the ammeter (D) starts to decrease after the maximum current value has reached the maximum value, and the time point when the decrease in the current value that has started to decrease has converged is measured at the welding completion point. 6. The method for high-frequency welding of an object to be welded according to claim 5, wherein the current value to be set is set as a HI reference and the energy output is stopped when the HI reference is passed . 前記溶着開始点から前記溶着完了点までの時間を溶着時間とし、計測した溶着時間があらかじめ設定した許容時間を超えた場合には、高周波発振回路の発振管の異常あるいは自然消耗による能力低下が生じたとして判断することを特徴とする請求項５記載の被溶着物の高周波溶着方法。 When the time from the welding start point to the welding completion point is the welding time, and the measured welding time exceeds a preset allowable time, the capacity of the high-frequency oscillation circuit is deteriorated due to abnormality or natural wear. 6. The method of high-frequency welding of an object to be welded according to claim 5, characterized in that it is determined that the welding object is high .
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