JP3914760B2

JP3914760B2 - Single-turn induction heating coil

Info

Publication number: JP3914760B2
Application number: JP2001381522A
Authority: JP
Inventors: 康弘真弓; 英司坪田; 亮朝日山; 育世野村
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 2001-12-14
Filing date: 2001-12-14
Publication date: 2007-05-16
Anticipated expiration: 2021-12-14
Also published as: JP2003187950A

Description

【０００１】
【発明の属する技術分野】
本発明は、金属帯板の誘導加熱用コイル、特にシングルターンコイルに関する。
【０００２】
【従来の技術】
誘導加熱とは、交流電源に接続されたコイルを被加熱物の周囲に配置し、交番磁界により誘起される渦電流のジュール熱により物体を加熱する方法である。誘導加熱には、交番磁界を被加熱物に垂直に交差させるトランスバース方式と、コイルで被加熱物を巻くように配置して、交番磁界を被加熱物に平行に印加するソレノイド方式の２通りがあり、目的によって選択される。
金属帯板の加熱の場合、板幅方向に均一な加熱が必要なことから、ソレノイド方式が適している。また、ソレノイド方式には、１つの電源に対して、複数回コイルを巻くマルチターン方式と、１回だけ巻くシングルターン方式がある。
【０００３】
図１０は、特開平８−８０５１号公報および特開平７−２５２６２８号公報に開示されたソレノイド方式のシングルターンコイルを用いる金属帯板の誘導加熱装置を示した図である。この誘導加熱装置は、金属帯板１の表面２および裏面３と所定の間隔を空けて、金属帯板１の幅方向に延び両端が金属帯板の幅方向より外側に位置する表面側の導体部４および裏面側の導体部５、この表面側の導体部４および裏面側の導体部５の一端を、金属帯板１の幅方向の、片方の端部の外側で金属帯板１の板厚方向に延びる導体部６にて接続してなるシングルターン型誘導加熱コイル７, このコイル７の表面側の導体部４および裏面側の導体部５の他端に交流を印加える交流電源装置Ｓを備えている。
しかし、この従来技術では、加熱後の鋼板形状の悪化を防止するために加熱速度を抑えるべく、有効加熱長さを長くするために複数のシングルターン型誘導加熱コイルを金属帯板の進行方向に配置して金属帯板の誘導加熱炉を構成する場合には、コイル数に相当する電源装置が必要であり設備費が高価になるという問題点があった。
【０００４】
また、この従来のシングルターン型誘導加熱コイルでは、金属帯板の断面方向から見て、金属帯板両端面外側のコイル端部は閉塞されるため、コイルを電源と共に金属帯板の搬送ラインから外側に出すことができず、コイルの保守・点検が困難であった。
さらに、従来のソレノイド方式のシングルターンコイルを用いる誘導加熱装置は、金属帯板１が、例えば磁性体の鋼帯である場合、キュリー点（約７５０℃）以上の加熱が困難であり、６５０℃以下の低温領域での加熱にしか適用できないという問題点があった。さらに、金属帯板１が、例えばアルミ, ＳＵＳ等の非磁性体である場合、加熱すること自体が困難であった。
磁性体帯板のキュリー点以上の加熱が困難な理由は、キュリー点付近の温度になると渦電流の電流浸透深さが大きくなり、板幅方向断面の表層部を一周している渦電流の表裏相殺が発生し、渦電流が流れなくなるからである。
また、非磁性体帯板を加熱すること自体が困難になる理由は、常温レベルから渦電流の電流浸透深さが大きく、板幅方向断面の表層部を一周している渦電流の表裏相殺が発生し、渦電流が流れないからである。
【０００５】
【発明が解決しようとする課題】
本発明は、前記のような従来技術の問題点を解決し、加熱速度を抑えるべく有効加熱長を長くしても設備費の低減が図れ、コイルの保守・点検が容易で、かつ、鋼帯をキュリー点以上に加熱できるシングルターン型誘導加熱コイルを提供することを課題とする。
【０００６】
【課題を解決するための手段】
本発明の要旨とするところは、特許請求の範囲に記載した通りの下記内容である。
（１）金属帯板と、前記金属帯板の表面および裏面と所定間隔を存して、金属帯板の幅方向に延びて両端が前記金属帯板の両端より外側に位置する表面側の第１の導体部および裏面側の第２の導体部と、
前記金属帯板の幅方向の端部の外側で金属帯板の板厚方向に延びて、前記第１の導体部および前記第２の導体部の各一端を接続する第３の導体部とを備えたシングルターン型誘導加熱コイルであって、
前記第１の導体部および前記第２の導体部をそれぞれ１本ずつ増設し、２本の前記第１の導体部および前記第２の導体部の各開放端を、前記金属帯板の長手方向に延びる第４の導体部で接続し、
前記第１の導体部と第２の導体部とを前記金属帯板の長手方向に互いに、前記第１の導体部と第２の導体部の幅Ｗだけシフトした位置に設置し、かつ、
第１の導体部及び第２の導体部それぞれに増設された導体部をフェライトコアで被覆し、第１の導体部を被覆するフェライトコアと増設された導体部を被覆するフェライトコアとを接触させるとともに、第２の導体部を被覆するフェライトコアと増設された導体部を被覆するフェライトコアとを接触させることにより金属帯板を幅方向均一に加熱することができるようにしたことを特徴とするシングルターン型誘導加熱コイル。
【０００７】
（２）金属帯板と、前記金属帯板の表面および裏面と所定間隔を存して、金属帯板の幅方向に延びて両端が前記金属帯板の両端より外側に位置する表面側の第１の導体部および裏面側の第２の導体部と、
前記金属帯板の幅方向の端部の外側で金属帯板の板厚方向に延びて、前記第１の導体部および前記第２の導体部の各一端を接続する第３の導体部とを備えたシングルターン型誘導加熱コイルであって、
前記第１の導体部および前記第２の導体部と前記金属帯板の長手方向に平行に、前記第１の導体部および前記第２の導体部をそれぞれ２本以上増設し、３本以上の前記第１の導体部および前記第２の導体部の各開放端を、前記金属帯板の長手方向で左右交互に延びる第４の導体部で接続し、
前記第１の導体部と第２の導体部とを前記金属帯板の長手方向に互いに、前記第１の導体部と第２の導体部の幅Ｗだけシフトした位置に設置し、かつ、
第１の導体部及び第２の導体部それぞれに増設された導体部をフェライトコアで被覆し、第１の導体部を被覆するフェライトコアと増設された導体部を被覆するフェライトコアとを接触させるとともに、第２の導体部を被覆するフェライトコアと増設された導体部を被覆するフェライトコアとを接触させることにより金属帯板を幅方向均一に加熱することができるようにしたことを特徴とするシングルターン型誘導加熱コイル。
【０００８】
（３）前記第１の導体部および前記第２の導体部の増設本数がそれぞれ３本以上の奇数本であり、それぞれ４本以上の偶数本の前記第１の導体部および前記第２の導体部の開放端を、前記第４の導体部で接続することを特徴とする（２）に記載のシングルターン型誘導加熱コイル。
【０００９】
【発明の実施の形態】
本発明の実施の形態を、図１乃至図９を用いて詳細に説明する。
（第１の実施形態）
図１は、本発明における金属帯板の表面および裏面に設置する第１および第２の導体部をそれぞれ２本の導体とした実施形態を示す図である。
電源装置Ｓから供給される電流は、導体９,１１,４,６,５,１２,１０を経由して電源装置Ｓに通電される。
ここに、導体９および導体４が本発明における第１の導体部に相当し、
導体５および導体１０が本発明における第２の導体部に相当する。
また、導体６が本発明における第３の導体部に相当し、導体１１および導体１２が本発明における第４の導体部に相当する。
このように、第１および第２の導体が２本の導体により構成されていることにより、電源装置Ｓをコイルごとに設置することなく、金属帯板１の長手方向の有効加熱長を長くすることができ、加熱速度を抑制することにより、加熱後の金属帯板１の形状悪化を防止することができる。
また、金属帯板１の幅方向の片側のコイル端部が開放されているため、コイルを電源と共に、金属帯板１の搬送ラインより外側に搬出することができ、コイルの保守・点検・整備が容易である。
【００１０】
さらに、導体９および導体４が、導体１０および導体５に対して、金属帯板１の長手方向にシフトした位置に設置されている。これにより、金属帯板１の板幅方向断面の表層部を一周している渦電流の表裏相殺の発生を防止できることから鋼板においてはキュリー点以上の加熱が可能となり、また、アルミやＳＵＳなどの非磁性体の加熱もできる。
図３は、図１の電源装置Ｓ側から見た断面図であり、図４は逆側から見た断面図である。
金属帯板表面の導体９および導体４が、裏面の導体１０および導体５に対して帯板の長手方向に図中のＷだけシフトしている様子がわかる。また、第３の導体部に相当する導体６がＬ字形状になっており、これによりシフトされた導体４と導体５を金属帯板の板厚方向に接続している。
【００１１】
（第２の実施形態）
図２は、本発明における金属帯板の表面および裏面に設置する第１および第２の導体部をそれぞれ３本の導体とした実施形態を示す図である。
電源装置Ｓから供給される電流は、導体１４,１１,９,１１,４,６,５,１２,１０,１２,１５を経由して電源装置Ｓに通電される。
ここに、導体１４,導体９および導体４が本発明における第１の導体部に相当し、導体５,導体１０および導体１５が本発明における第２の導体部に相当する。
また、導体６が本発明における第３の導体部に相当し、導体１１および導体１２が本発明における第４の導体部に相当する。
このように、第１および第２の導体部が３本の導体により構成されていることにより、電源装置Ｓをコイルごとに設置することなく、金属帯板１の長手方向の有効加熱長を長くすることができ、加熱速度を抑制することにより、加熱後の金属帯板１の形状悪化を防止することができる。
【００１２】
さらに、導体１４、導体９および導体４が、導体１５,導体１０および導体５に対して、金属帯板１の長手方向にシフトした位置に設置されている。これにより、金属帯板１の板幅方向断面の表層部を一周している渦電流の表裏相殺の発生を防止できることから鋼板においてはキュリー点以上の加熱が可能となり、また、アルミやＳＵＳなどの非磁性体の加熱もできる。
図５は、図２の電源装置Ｓ側から見た断面図であり、図６は逆側から見た断面図である。
金属帯板表面の導体１４,導体９および導体４が、裏面の導体１５, 導体１０および導体５に対して帯板の長手方向に図中のＷだけシフトしている様子がわかる。また、第３の導体部に相当する導体６がＬ字形状になっており、これによりシフトされた導体４と導体５を金属帯板の板厚方向に接続している。
【００１３】
（第３の実施形態）
図７は、本発明における金属帯板の表面および裏面に設置する第１および第２の導体部をそれぞれ４本の導体とした実施形態を示す図である。
電源装置Ｓから供給される電流は、導体１７,１１,１４,１１,９,１１,４,６,５,１２,１０,１２,１５,１２,１８を経由して電源装置Ｓに通電される。
ここに、導体１７,導体１４,導体９および導体４が本発明における第１の導体部に相当し、導体５,導体１０,導体１５および導体１８が本発明における第２の導体部に相当する。
【００１４】
また、導体６が本発明における第３の導体部に相当し、導体１１および導体１２が本発明における第４の導体部に相当する。
このように、第１および第２の導体が４本の導体により構成されていることにより、電源装置Ｓをコイルごとに設置することなく、金属帯板１の長手方向の有効加熱長を長くすることができ、加熱速度を抑制することにより、加熱後の金属帯板１の形状悪化を防止することができる。
また、金属帯板１の幅方向の片側のコイル端部が開放されているため、コイルを電源と共に、金属帯板１の搬送ラインより外側に搬出することができ、コイルの保守・点検・整備が容易である。この効果は、第１および第２の導体部をそれぞれ４本以上の偶数本の導体とした場合にも同様の効果が得られる。
さらに、導体１７,導体１４,導体９および導体４が、導体１８,導体１５,導体１０および導体５に対して、金属帯板１の長手方向にシフトした位置に設置されている。これにより、金属帯板１の板幅方向断面の表層部を一周している渦電流の表裏相殺の発生を防止できることから鋼板においてはキュリー点以上の加熱が可能となり、また、アルミやＳＵＳなどの非磁性体の加熱もできる。
【００１５】
図８は、図７の電源装置Ｓ側から見た断面図であり、図９は逆側から見た断面図である。
金属帯板表面の導体１７,導体１４,導体９および導体４が、導体１８,導体１５,導体１０および導体５に対して帯板の長手方向に図中のＷだけシフトしている様子がわかる。また、第３の導体部に相当する導体６がＬ字形状になっており、これによりシフトされた導体４と導体５を金属帯板の板厚方向に接続している。
なお、上記の第１乃至第３の実施形態に共通する加熱用の導体は以下の実施形態が好ましい。
加熱用の導体は、電気抵抗が小さく、入手し易さを考慮して、断面が四角形の中空水冷の銅パイプが好ましい。
【００１６】
また、磁場を集中させ（磁束密度を高め）、加熱効率を向上させるために、金属帯板の表面側および裏面側の導体４,５,９,１０,１４,１５,１７,１８の金属帯板１の表面２および裏面３の対向面を除く外周３面を比透磁率２５００と高く、高抵抗率のフェライトコア２１で直接被覆することが好ましい。
このように構成したシングルターンコイルによれば、交流電源装置Ｓにより、交流電源を流すとコイルが発生する交番時間の磁気回路抵抗をフェライトコア２１により小さくでき、磁束密度を大きくでき、金属帯板１に発生する渦電流を大きくできる。このため金属帯板１を所定温度まで加熱するのに要する時間（加熱時間）を短縮できる。またフェライトよりなるコア中を前記交番磁界が通過するが、フェライトは高抵抗率材料でもあることから渦電流は形成されず、これによるコア温度上昇はない。さらにフェライトは高抵抗率材料であるからコアをコイルに被覆する際に電気絶縁層を設ける必要がなく、密に接触して被覆できる。誘導加熱された金属帯板１からコアへの輻射熱もコイル損傷防止のために設けられる中空水冷コイル構造によって、良好に伝達抜熱することが好ましい。これにより、コア損傷防止のための格別の冷却機構を要しない。
【００１７】
【実施例】
本発明を鋼帯の加熱に用いた場合の実施例について以下に詳細に説明する。
図１に示す、コイル導体幅Ｗ＝６ｍｍ、コア幅ｈ＝３．５ｍｍ、コイル間ギャップＧ＝６ｍｍのシングルターンコイルを用いて、常温の鋼帯の連続加熱を行った。使用した鋼帯は、板幅７０ｍｍ、板厚ｔ＝０．２３ｍｍのものを、通板速度Ｖ＝２００ｍｍ／ｓで通板した。また、電源周波数ｆについては、実用されている最も高周波数の２００ＫＨｚで鋼帯の連続加熱を行った。その際、加熱直後（図３の位置a）の幅方向のセンター部、最エッジ部、エッジから１０ｍｍ部の温度を測定した。その結果を表１に示す。なお、鋼帯のキュリー点温度は７５０℃である。
比較のために、従来のシングルターンコイルを用いて、コイル導体幅Ｗ＝６ｍｍ、コア幅ｈ＝３．５ｍｍ、コイル間ギャップＧ＝６ｍｍのシングルターンコイルを用いて、前記と同一の条件で鋼帯の連続加熱を行い、加熱直後（図３の位置a）の温度を測定したその結果を表１に示す。
【００１８】
【表１】

表１から、本発明のシングルターンコイルは、鋼帯を幅方向均一にキュリー点以上に加熱することができることがわかる。一方、比較例１の加熱温度はキュリー点温度未満となっている。
次に、記と同じ条件で、ＳＵＳ帯の連続加熱を行い、加熱直後（図３の位置a）の温度を測定した。その結果を表２に示す。
【００１９】
【表２】

表２から、本発明のシングルターンコイルは、ＳＵＳ帯のような非磁性金属帯を幅方向均一に加熱することができることがわかる。一方、比較例２は、全く加熱できていない。
【００２０】
【発明の効果】
本発明によれば、加熱速度を抑えるべく有効加熱長を長くしても電源装置を追加する必要がないため設備費の低減が図れ、金属帯板の板幅方向の断面方向において導体が閉鎖されておらず、一端が開放されているためコイルの保守・点検が容易なシングルターン型誘導加熱コイルを提供することができる。
しかも、金属帯板の表裏面で導体を長手方向にシフトさせることにより鋼帯をキュリー点以上に加熱でき、さらにＳＵＳなどの非磁性体も加熱できるなど、産業上有用な、著しい効果を奏する。
【００２１】
なお、本発明によれば、加熱速度を抑制し易い従来のガス加熱炉と比較して、以下の効果がある。
設置スペースが従来のガス加熱炉の１０分の１程度でよい。
ガス加熱炉での加熱効率は、温度が低い範囲（例えば鋼板温度が１００℃前後）では、０．３程度であり、温度が高い範囲（例えば鋼板温度が８００℃）では０．１程度である。これに比べて、本発明のシングルターン型誘導加熱コイルによれば、加熱温度の高低に関係なく加熱効率が０．６〜０．７程度であるため加熱長さを低減できる。
熱応答性が良いため、操業が行い易い。
例えば、鋼板の種類の切り替え等を行う場合には、ガス加熱炉の場合は炉の温度設定を変更するのに３０分程度の時間が必要であるが、本発明のシングルターン型誘導加熱コイルによれば、投入電力設定を変更するだけでほとんど設定変更直後に炉温の変更が行える。
【図面の簡単な説明】
【図１】本発明における金属帯板の表面および裏面に設置する第１および第２の導体部をそれぞれ２本の導体とした実施形態を示す図である。
【図２】本発明における金属帯板の表面および裏面に設置する第１および第２の導体部をそれぞれ３本の導体とした実施形態を示す図である。
【図３】本発明のシングルターン型誘導加熱コイルを図１の電源装置Ｓ側から見た断面図である。
【図４】本発明のシングルターン型誘導加熱コイルを図１の電源装置Ｓの逆側から見た断面図である。
【図５】本発明のシングルターン型誘導加熱コイルを図２の電源装置Ｓ側から見た断面図である。
【図６】本発明のシングルターン型誘導加熱コイルを図２の電源装置Ｓの逆側から見た断面図である。
【図７】本発明における金属帯板の表面および裏面に設置する第１および第２の導体部をそれぞれ４本の導体とした実施形態を示す図である。
【図８】本発明のシングルターン型誘導加熱コイルを図７の電源装置Ｓ側から見た断面図である。
【図９】本発明のシングルターン型誘導加熱コイルを図７の電源装置Ｓの逆側から見た断面図である。
【図１０】従来のシングルターン型誘導加熱コイルを示す図である。
【符号の説明】
１：金属帯板
２：帯板表面
３：帯板裏面
４：金属帯板の幅方向に延びる帯板表面側導体
５：金属帯板の幅方向に延びる帯板裏面側導体
６：金属帯板板厚方向に延びる導体
７：従来のシングルターン型誘導加熱コイル
８：本発明のシングルターン型誘導加熱コイル
９：金属帯板の幅方向に延びる帯板表面側導体
１０：金属帯板の幅方向に延びる帯板裏面側導体
１１：金属帯板の長手方向に延びる導体
１２：金属帯板の長手方向に延びる導体
１３：本発明のシングルターン型誘導加熱コイル
１４：金属帯板の幅方向に延びる帯板表面側導体
１５：金属帯板の幅方向に延びる帯板裏面側導体
１６：本発明のシングルターン型誘導加熱コイル
１７：金属帯板の幅方向に延びる帯板表面側導体
１８：金属帯板の幅方向に延びる帯板裏面側導体
１９：銅パイプ
２１：フェライトコア[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coil for induction heating of a metal strip, particularly a single turn coil.
[0002]
[Prior art]
Induction heating is a method in which a coil connected to an AC power source is arranged around an object to be heated, and an object is heated by Joule heat of eddy current induced by an alternating magnetic field. There are two types of induction heating: a transverse method in which an alternating magnetic field intersects the object to be heated vertically and a solenoid method in which the object to be heated is wound around a coil and an alternating magnetic field is applied in parallel to the object to be heated. Is selected according to purpose.
In the case of heating a metal strip, a solenoid system is suitable because uniform heating is required in the plate width direction. The solenoid system includes a multi-turn system in which a coil is wound a plurality of times and a single-turn system in which the coil is wound only once.
[0003]
FIG. 10 is a view showing an induction heating apparatus for a metal strip using a solenoid type single turn coil disclosed in Japanese Patent Application Laid-Open Nos. 8-8051 and 7-252628. This induction heating device is a conductor on the surface side that extends in the width direction of the metal strip 1 and has both ends positioned outside the width direction of the metal strip with a predetermined spacing from the front surface 2 and the back surface 3 of the metal strip 1. One end of the conductor 4 on the back surface side and the conductor portion 5 on the back surface side and the conductor portion 4 on the front surface side and the conductor portion 5 on the back surface side of the metal band plate 1 outside the one end in the width direction of the metal strip 1 A single-turn induction heating coil 7 connected by a conductor portion 6 extending in the thickness direction, an AC power supply device S for applying an alternating current to the other end of the conductor portion 4 on the front surface side and the conductor portion 5 on the back surface side of the coil 7 It has.
However, in this prior art, in order to suppress the heating rate in order to prevent deterioration of the steel plate shape after heating, a plurality of single-turn induction heating coils are arranged in the traveling direction of the metal strip to increase the effective heating length. In the case of arranging the induction heating furnace of the metal strip by arranging, there is a problem that a power supply device corresponding to the number of coils is necessary and the equipment cost becomes expensive.
[0004]
In addition, in this conventional single-turn induction heating coil, the coil ends on both sides of the metal band plate are closed when viewed from the cross-sectional direction of the metal band plate. The coil could not be pulled out, making it difficult to maintain and inspect the coil.
Furthermore, in the conventional induction heating apparatus using a solenoid type single-turn coil, when the metal strip 1 is a magnetic steel strip, for example, it is difficult to heat the Curie point (about 750 ° C.) or more, and 650 ° C. There is a problem that it can be applied only to heating in the following low temperature region. Furthermore, when the metal strip 1 is a non-magnetic material such as aluminum or SUS, it is difficult to heat itself.
The reason why it is difficult to heat the magnetic strip above the Curie point is that when the temperature near the Curie point is reached, the current penetration depth of the eddy current increases, and the front and back of the eddy current that goes around the surface layer of the cross section in the plate width direction This is because cancellation occurs and eddy current does not flow.
The reason why heating the non-magnetic strip itself is difficult is that the current penetration depth of the eddy current is large from the normal temperature level, and the front / back offset of the eddy current that goes around the surface layer part of the cross section in the plate width direction is cancelled. This is because eddy current does not flow.
[0005]
[Problems to be solved by the invention]
The present invention solves the problems of the prior art as described above, and can reduce the equipment cost even if the effective heating length is increased in order to suppress the heating rate, and the coil can be easily maintained and inspected. It is an object of the present invention to provide a single-turn induction heating coil that can heat the coil to the Curie point or higher.
[0006]
[Means for Solving the Problems]
The gist of the present invention is the following contents as described in the claims.
(1) A metal band plate, a front surface and a back surface of the metal band plate, extending in the width direction of the metal band plate and having both ends positioned outside the both ends of the metal band plate. A first conductor portion and a second conductor portion on the back side;
A third conductor portion extending in the thickness direction of the metal strip outside the end in the width direction of the metal strip and connecting each end of the first conductor portion and the second conductor portion; A single-turn induction heating coil provided,
One each of the first conductor portion and the second conductor portion is added, and the open ends of the two first conductor portions and the second conductor portion are arranged in the longitudinal direction of the metal strip. Connected by a fourth conductor extending to
Installing the first conductor portion and the second conductor portion at a position shifted from each other in the longitudinal direction of the metal strip by a width W of the first conductor portion and the second conductor portion; and
The conductor part added to each of the first conductor part and the second conductor part is covered with a ferrite core, and the ferrite core covering the first conductor part and the ferrite core covering the added conductor part are brought into contact with each other. In addition, the metal strip can be heated uniformly in the width direction by bringing the ferrite core covering the second conductor portion into contact with the ferrite core covering the added conductor portion. Single-turn induction heating coil.
[0007]
(2) A metal band plate, a front surface and a back surface of the metal band plate, having a predetermined interval, extending in the width direction of the metal band plate and having both ends positioned outside the both ends of the metal band plate. A first conductor portion and a second conductor portion on the back side;
A third conductor portion extending in the thickness direction of the metal strip outside the end in the width direction of the metal strip and connecting each end of the first conductor portion and the second conductor portion; A single-turn induction heating coil provided,
Two or more each of the first conductor part and the second conductor part are added in parallel with the longitudinal direction of the first conductor part and the second conductor part and the metal strip, and three or more Connecting each open end of the first conductor portion and the second conductor portion with a fourth conductor portion extending alternately left and right in the longitudinal direction of the metal strip,
Installing the first conductor portion and the second conductor portion at a position shifted from each other in the longitudinal direction of the metal strip by a width W of the first conductor portion and the second conductor portion; and
The conductor part added to each of the first conductor part and the second conductor part is covered with a ferrite core, and the ferrite core covering the first conductor part and the ferrite core covering the added conductor part are brought into contact with each other. In addition, the metal strip can be heated uniformly in the width direction by bringing the ferrite core covering the second conductor portion into contact with the ferrite core covering the added conductor portion. Single-turn induction heating coil.
[0008]
(3) The number of extension of the first conductor portion and the second conductor portion is an odd number of 3 or more, and the even number of the first conductor portion and the second conductor are 4 or more, respectively. The single-turn induction heating coil according to (2), wherein the open ends of the parts are connected by the fourth conductor part.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described in detail with reference to FIGS.
(First embodiment)
FIG. 1 is a view showing an embodiment in which the first and second conductor portions installed on the front and back surfaces of the metal strip in the present invention are each made of two conductors.
The current supplied from the power supply device S is supplied to the power supply device S through the

conductors

9, 11, 4, 6, 5, 12, and 10.
Here, the conductor 9 and the conductor 4 correspond to the first conductor portion in the present invention,
The conductor 5 and the conductor 10 correspond to the second conductor portion in the present invention.
The conductor 6 corresponds to the third conductor portion in the present invention, and the conductor 11 and the conductor 12 correspond to the fourth conductor portion in the present invention.
Thus, the 1st and 2nd conductor is comprised by two conductors, and it lengthens the effective heating length of the longitudinal direction of the metal strip 1 without installing the power supply device S for every coil. It is possible to prevent the deterioration of the shape of the metal strip 1 after heating by suppressing the heating rate.
In addition, since the coil end on one side in the width direction of the metal strip 1 is open, the coil can be carried out together with the power source to the outside from the conveying line of the metal strip 1, and the coil is maintained, inspected and maintained. Is easy.
[0010]
Furthermore, the conductor 9 and the conductor 4 are installed at positions shifted in the longitudinal direction of the metal strip 1 with respect to the conductor 10 and the conductor 5. As a result, it is possible to prevent front and back cancellation of eddy currents that circulate around the surface layer portion of the cross section in the width direction of the metal strip 1, so that heating above the Curie point is possible in the steel sheet, and aluminum, SUS, etc. Non-magnetic materials can also be heated.
3 is a cross-sectional view as seen from the power supply device S side of FIG. 1, and FIG. 4 is a cross-sectional view as seen from the opposite side.
It can be seen that the conductor 9 and the conductor 4 on the surface of the metal strip are shifted by W in the figure in the longitudinal direction of the strip with respect to the conductor 10 and the conductor 5 on the back. The conductor 6 corresponding to the third conductor portion is L-shaped, and the conductor 4 and the conductor 5 shifted thereby are connected in the thickness direction of the metal strip.
[0011]
(Second Embodiment)
FIG. 2 is a view showing an embodiment in which the first and second conductor portions installed on the front surface and the back surface of the metal strip in the present invention each have three conductors.
The current supplied from the power supply S is energized to the power supply S via the

conductors

14, 11, 9, 11, 4, 6, 5, 12, 10, 12, 15.
Here, the conductor 14, the conductor 9, and the conductor 4 correspond to the first conductor portion in the present invention, and the conductor 5, the conductor 10, and the conductor 15 correspond to the second conductor portion in the present invention.
The conductor 6 corresponds to the third conductor portion in the present invention, and the conductor 11 and the conductor 12 correspond to the fourth conductor portion in the present invention.
As described above, since the first and second conductor portions are formed of the three conductors, the effective heating length in the longitudinal direction of the metal strip 1 is increased without installing the power supply device S for each coil. By suppressing the heating rate, it is possible to prevent the deterioration of the shape of the metal strip 1 after heating.
[0012]
Furthermore, the conductor 14, the conductor 9, and the conductor 4 are installed at positions shifted in the longitudinal direction of the metal strip 1 with respect to the conductor 15, the conductor 10, and the conductor 5. As a result, it is possible to prevent front and back cancellation of eddy currents that circulate around the surface layer portion of the cross section in the width direction of the metal strip 1, so that heating above the Curie point is possible in the steel sheet, and aluminum, SUS, etc. Non-magnetic materials can also be heated.
5 is a cross-sectional view seen from the power supply device S side of FIG. 2, and FIG. 6 is a cross-sectional view seen from the opposite side.
It can be seen that the conductor 14, the conductor 9 and the conductor 4 on the surface of the metal strip are shifted by W in the figure in the longitudinal direction of the strip with respect to the conductor 15, the conductor 10 and the conductor 5 on the back. The conductor 6 corresponding to the third conductor portion is L-shaped, and the conductor 4 and the conductor 5 shifted thereby are connected in the thickness direction of the metal strip.
[0013]
(Third embodiment)
FIG. 7 is a view showing an embodiment in which the first and second conductor portions installed on the front surface and the back surface of the metal strip in the present invention each have four conductors.
The current supplied from the power supply S is supplied to the power supply S via the

conductors

17, 11, 14, 11, 9, 11, 4, 6, 5, 12, 10, 12, 15, 12, 18. The
Here, the conductor 17, the conductor 14, the conductor 9, and the conductor 4 correspond to the first conductor portion in the present invention, and the conductor 5, the conductor 10, the conductor 15, and the conductor 18 correspond to the second conductor portion in the present invention. .
[0014]
The conductor 6 corresponds to the third conductor portion in the present invention, and the conductor 11 and the conductor 12 correspond to the fourth conductor portion in the present invention.
As described above, since the first and second conductors are constituted by four conductors, the effective heating length in the longitudinal direction of the metal strip 1 is increased without installing the power supply device S for each coil. It is possible to prevent the deterioration of the shape of the metal strip 1 after heating by suppressing the heating rate.
In addition, since the coil end on one side in the width direction of the metal strip 1 is open, the coil can be carried out together with the power source to the outside from the conveying line of the metal strip 1, and the coil is maintained, inspected and maintained. Is easy. This effect is also obtained when the first and second conductor portions are each an even number of four or more conductors.
Furthermore, the conductor 17, the conductor 14, the conductor 9, and the conductor 4 are installed at positions shifted in the longitudinal direction of the metal strip 1 with respect to the conductor 18, the conductor 15, the conductor 10, and the conductor 5. As a result, it is possible to prevent front and back cancellation of eddy currents that circulate around the surface layer portion of the cross section of the metal strip 1 in the plate width direction. Non-magnetic materials can also be heated.
[0015]
8 is a cross-sectional view seen from the power supply device S side of FIG. 7, and FIG. 9 is a cross-sectional view seen from the opposite side.
It can be seen that the conductor 17, conductor 14, conductor 9 and conductor 4 on the surface of the metal strip are shifted by W in the figure in the longitudinal direction of the strip with respect to the conductor 18, conductor 15, conductor 10 and conductor 5. . The conductor 6 corresponding to the third conductor portion is L-shaped, and the conductor 4 and the conductor 5 shifted thereby are connected in the thickness direction of the metal strip.
The heating conductor common to the first to third embodiments is preferably the following embodiment.
The heating conductor is preferably a hollow water-cooled copper pipe having a square cross section in view of low electrical resistance and availability.
[0016]
Further, in order to concentrate the magnetic field (increase the magnetic flux density) and improve the heating efficiency, the metal bands of the

conductors

4, 5, 9, 10, 14, 15, 17, 18 on the front side and the back side of the metal band plate are used. It is preferable that the outer peripheral three surfaces excluding the opposing surfaces of the front surface 2 and the rear surface 3 of the plate 1 are directly covered with a ferrite core 21 having a high relative permeability 2500 and a high resistivity.
According to the single turn coil configured as described above, the AC power source S can reduce the magnetic circuit resistance during the alternating time generated by the coil when the AC power is supplied to the ferrite core 21 and increase the magnetic flux density. The eddy current generated in 1 can be increased. For this reason, the time (heating time) required to heat the metal strip 1 to a predetermined temperature can be shortened. The alternating magnetic field passes through the core made of ferrite, but since ferrite is also a high resistivity material, eddy currents are not formed and the core temperature does not increase. Further, since ferrite is a high resistivity material, it is not necessary to provide an electrical insulating layer when coating the core on the coil, and it can be coated in close contact. It is preferable that the radiant heat from the induction-heated metal strip 1 to the core is well transferred and removed by a hollow water-cooled coil structure provided to prevent coil damage. This eliminates the need for a special cooling mechanism for preventing core damage.
[0017]
【Example】
Examples in which the present invention is used for heating a steel strip will be described in detail below.
Using a single turn coil having a coil conductor width W = 6 mm, a core width h = 3.5 mm, and an inter-coil gap G = 6 mm shown in FIG. The steel strip used had a plate width of 70 mm and a plate thickness t = 0.23 mm, and was passed at a plate passing speed V = 200 mm / s. As for the power supply frequency f, the steel strip was continuously heated at the highest practical frequency of 200 KHz. At that time, the temperature of the center part in the width direction immediately after heating (position a in FIG. 3), the outermost edge part, and the 10 mm part from the edge was measured. The results are shown in Table 1. In addition, the Curie point temperature of a steel strip is 750 degreeC.
For comparison, a conventional single turn coil is used, and a single turn coil having a coil conductor width W = 6 mm, a core width h = 3.5 mm, and an inter-coil gap G = 6 mm is used. Table 1 shows the results of continuous heating of the band and measuring the temperature immediately after heating (position a in FIG. 3).
[0018]
[Table 1]

From Table 1, it can be seen that the single turn coil of the present invention can uniformly heat the steel strip to the Curie point or more in the width direction. On the other hand, the heating temperature of Comparative Example 1 is less than the Curie point temperature.
Next, continuous heating of the SUS band was performed under the same conditions as described above, and the temperature immediately after heating (position a in FIG. 3) was measured. The results are shown in Table 2.
[0019]
[Table 2]

From Table 2, it can be seen that the single turn coil of the present invention can uniformly heat a non-magnetic metal band such as a SUS band in the width direction. On the other hand, Comparative Example 2 could not be heated at all.
[0020]
【The invention's effect】
According to the present invention, even if the effective heating length is increased to suppress the heating rate, it is not necessary to add a power supply device, so that the equipment cost can be reduced, and the conductor is closed in the cross-sectional direction in the plate width direction of the metal strip. In addition, since the one end is open, a single-turn induction heating coil that facilitates coil maintenance and inspection can be provided.
In addition, by shifting the conductor in the longitudinal direction on the front and back surfaces of the metal strip, the steel strip can be heated to the Curie point or higher, and nonmagnetic materials such as SUS can also be heated.
[0021]
In addition, according to this invention, compared with the conventional gas heating furnace which is easy to suppress a heating rate, there exist the following effects.
The installation space may be about one-tenth that of a conventional gas heating furnace.
The heating efficiency in the gas heating furnace is about 0.3 when the temperature is low (for example, the steel plate temperature is around 100 ° C.), and is about 0.1 when the temperature is high (for example, the steel plate temperature is 800 ° C.). . In contrast, according to the single-turn induction heating coil of the present invention, the heating length can be reduced because the heating efficiency is about 0.6 to 0.7 regardless of the heating temperature.
Easy to operate due to good thermal response.
For example, when switching the type of steel sheet, etc., in the case of a gas heating furnace, it takes about 30 minutes to change the furnace temperature setting. According to this, the furnace temperature can be changed almost immediately after the setting is changed by simply changing the input power setting.
[Brief description of the drawings]
FIG. 1 is a view showing an embodiment in which first and second conductor portions installed on the front and back surfaces of a metal strip in the present invention are each made of two conductors.
FIG. 2 is a view showing an embodiment in which the first and second conductor portions installed on the front and back surfaces of the metal strip in the present invention are each made of three conductors.
3 is a cross-sectional view of the single-turn induction heating coil of the present invention as viewed from the power supply device S side of FIG.
4 is a cross-sectional view of the single-turn induction heating coil of the present invention as viewed from the opposite side of the power supply device S of FIG.
5 is a cross-sectional view of the single-turn induction heating coil of the present invention viewed from the power supply device S side of FIG.
6 is a cross-sectional view of the single-turn induction heating coil of the present invention viewed from the opposite side of the power supply device S of FIG.
FIG. 7 is a view showing an embodiment in which the first and second conductor portions installed on the front and back surfaces of the metal strip in the present invention are each made of four conductors.
8 is a cross-sectional view of the single-turn induction heating coil of the present invention as viewed from the power supply device S side of FIG.
9 is a cross-sectional view of the single-turn induction heating coil of the present invention as viewed from the opposite side of the power supply device S of FIG.
FIG. 10 is a view showing a conventional single-turn induction heating coil.
[Explanation of symbols]
1: metal strip 2: strip surface 3: strip back surface 4: strip surface front conductor 5 extending in the width direction of the metal strip 5: strip back conductor 6 extending in the width direction of the metal strip 6: metal strip Conductor 7 extending in the plate thickness direction: Conventional single-turn induction heating coil 8: Single-turn induction heating coil 9 of the present invention 9: Strip surface side conductor 10 extending in the width direction of the metal strip 10: Width direction of the metal strip The strip back conductor 11 extending in the longitudinal direction of the metal strip 12: the conductor 12 extending in the longitudinal direction of the metal strip 13: the conductor extending in the longitudinal direction of the metal strip 13: the single-turn induction heating coil 14 of the present invention: extending in the width direction of the metal strip Band plate surface side conductor 15: Band plate back side conductor 16 extending in the width direction of the metal band plate: Single-turn induction heating coil 17 of the present invention: Band plate surface side conductor 18 extending in the width direction of the metal band plate: Metal band Strip back conductor 19 extending in the width direction of the plate: copper pad Flop 21: ferrite core

Claims

A first conductor on the surface side that extends in the width direction of the metal strip and has both ends positioned outside both ends of the metal strip, with a predetermined distance from the front and back surfaces of the metal strip, and the metal strip. A second conductor portion on the side and the back side;
A third conductor portion extending in the thickness direction of the metal strip outside the end in the width direction of the metal strip and connecting each end of the first conductor portion and the second conductor portion; A single-turn induction heating coil provided,
One each of the first conductor portion and the second conductor portion is added, and the open ends of the two first conductor portions and the second conductor portion are arranged in the longitudinal direction of the metal strip. Connected by a fourth conductor extending to
Installing the first conductor portion and the second conductor portion at a position shifted from each other in the longitudinal direction of the metal strip by a width W of the first conductor portion and the second conductor portion; and
The conductor part added to each of the first conductor part and the second conductor part is covered with a ferrite core, and the ferrite core covering the first conductor part and the ferrite core covering the added conductor part are brought into contact with each other. In addition, the metal strip can be heated uniformly in the width direction by bringing the ferrite core covering the second conductor portion into contact with the ferrite core covering the added conductor portion. Single-turn induction heating coil.

A first conductor on the surface side that extends in the width direction of the metal strip and has both ends positioned outside both ends of the metal strip, with a predetermined distance from the front and back surfaces of the metal strip, and the metal strip. A second conductor portion on the side and the back side;
A third conductor portion extending in the thickness direction of the metal strip outside the end in the width direction of the metal strip and connecting each end of the first conductor portion and the second conductor portion; A single-turn induction heating coil provided,
Two or more each of the first conductor part and the second conductor part are added in parallel with the longitudinal direction of the first conductor part and the second conductor part and the metal strip, and three or more Connecting each open end of the first conductor portion and the second conductor portion with a fourth conductor portion extending alternately left and right in the longitudinal direction of the metal strip,
Installing the first conductor portion and the second conductor portion at a position shifted from each other in the longitudinal direction of the metal strip by a width W of the first conductor portion and the second conductor portion; and
The conductor part added to each of the first conductor part and the second conductor part is covered with a ferrite core, and the ferrite core covering the first conductor part and the ferrite core covering the added conductor part are brought into contact with each other. In addition, the metal strip can be heated uniformly in the width direction by bringing the ferrite core covering the second conductor portion into contact with the ferrite core covering the added conductor portion. Single-turn induction heating coil.

The additional number of the first conductor part and the second conductor part is an odd number of 3 or more, respectively, and the even number of the first conductor part and the second conductor part of 4 or more are opened. The single-turn induction heating coil according to claim 2, wherein the ends are connected by the fourth conductor portion.