JP4029932B2

JP4029932B2 - Shaft-like heated object heating device

Info

Publication number: JP4029932B2
Application number: JP2003012560A
Authority: JP
Inventors: 英三長尾
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 2003-01-21
Filing date: 2003-01-21
Publication date: 2008-01-09
Anticipated expiration: 2023-01-21
Also published as: JP2004227861A

Description

【０００１】
【発明の属する技術分野】
本発明は軸状被加熱物を熱処理するのに利用される軸状被加熱物の加熱装置に関する。
【０００２】
【従来の技術】
軸状被加熱物を熱処理するに当たり、図５（Ａ）に示すような基本構成を有する装置が使用される場合がある。図中Ｗは軸状被加熱物、８０は軸状被加熱物Ｗの全体を加熱する多段ヒータ、９０は多段ヒータ８０を構成するヒータ８１、８２、８３への電力量を各々調節するため電力調節部である。まず、ヒータ８１、８２、８３の全てに交流を通電すると、軸状被加熱物Ｗの外表面が予備加熱される。このときの軸状被加熱物Ｗの軸方向の温度パターンは図５（Ｂ）に示す通りである。その後、ヒータ８１、８２、８３に与える各電力をこの順番で順次最大に変化させると、軸状被加熱物Ｗの外表面上の最高ピーク点が順番に移行する。このときの軸状被加熱物Ｗの軸方向の温度パターンは図５（Ｃ）に示す通りである。このような過程を経て軸状被加熱物が熱処理される（関連する装置として、例えば特許文献１に開示されたものがある。）
【０００３】
【特許文献１】
特開平６−６９１４１号公報
【０００４】
【発明が解決しようとする課題】
しかしながら、ヒータ８１、８２、８３を上下方向に並べた構造の多段ヒータ８０を用いて軸状被加熱物Ｗを加熱している以上、ヒータ８１、８２、８３に与える電力をこの順番に最大にしても、軸状被加熱物Ｗの表面上の最高温度点が図５（Ｃ）に示す通り軸方向に一定とはならずヒータ８１、８２、８３のピッチ間隔に応じて波うつ形になる。即ち、軸状被加熱物Ｗ上の最高温度点を軸方向に連続的に推移させることが不可能であり、この点が軸状被加熱物Ｗに対して所望の熱処理を行う上で大きな問題となっている。
【０００５】
本発明は上記した背景の下で創作されたものであり、その目的とするところは、従来装置に内在する問題を抜本的に解消することが可能な軸状被加熱物の加熱装置を提供することにある。
【０００６】
【課題を解決するための手段】
本発明の軸状被加熱物の加熱装置は、軸状被加熱物の全体をその周りから間接的に加熱する円筒状抵抗発熱体と、円筒状抵抗発熱体をその周りから誘導加熱する誘導円形コイルと、誘導円形コイルを円筒状抵抗発熱体に沿って連続的に相対移動させる移動機構とを備えており、円筒状抵抗発熱体を予め直接抵抗加熱したときの温度に比べて高い温度に誘導円形コイルを用いて部分的に誘導加熱させ、この状態で移動機構を動作させ、これを通じて軸状被加熱物上の最高温度領域を軸方向に連続的に推移させる構成となっている。
【０００７】
具体的には、軸状被加熱物の全体をその周りから間接的に加熱するカーボン製の円筒状抵抗発熱体と、円筒状抵抗発熱体を不活性ガス又は減圧の下に置くために円筒状抵抗発熱体を収容する石英菅と、石英菅外に配置されており且つ円筒状抵抗発熱体をその周りから誘導加熱する誘導円形コイルと、誘導円形コイルを円筒状抵抗発熱体及び石英菅に沿って連続的に相対移動させる移動機構とを備えており、円筒状抵抗発熱体を予め直接抵抗加熱したときの温度に比べて高い温度に誘導円形コイルを用いて部分的に誘導加熱させ、この状態で移動機構を動作させ、これを通じて軸状被加熱物上の最高温度領域を軸方向に連続的に推移させる構成にすると良い。
【０００８】
好ましくは、円筒状抵抗発熱体上における誘導円形コイル直下の誘導加熱領域の幅を狭くするためのシールドリングが誘導円形コイルの反移動方向側の付近に配設されており、移動機構を用いてシールドリングを円筒状抵抗発熱体に対して誘導円形コイルとともに相対移動させる構成にすることが望ましい。この場合、誘導円形コイルに対するシールドリングの位置関係が調整可能な構成にすることがより望ましい。
【０００９】
本発明の別の軸状被加熱物の加熱装置は、軸状被加熱物の全体をその周りから間接的に加熱する円筒状抵抗発熱体と、円筒状抵抗発熱体をその周りから誘導加熱する誘導円形コイルと、誘導円形コイルの反移動方向側の付近に配設され且つ円筒状抵抗発熱体に向けてその周りから冷却媒体を噴射する環状冷却ジャケットと、誘導円形コイル及び環状冷却ジャケットを円筒状抵抗発熱体に沿って連続的に相対移動させる移動機構とを備えており、円筒状抵抗発熱体を予め直接抵抗加熱したときの温度に比べて高い温度に誘導円形コイルを用いて部分的に誘導加熱させ、この状態で移動機構及び環状冷却ジャケットを動作させ、これを通じて軸状被加熱物上の最高温度領域を軸方向に連続的に推移させる構成となっている。
【００１０】
具体的には、円筒状抵抗発熱体として二珪化モリブデン製のものを用いるようにすると良い。
【００１１】
好ましくは、環状冷却ジャケットは電磁シールドに適した素材を用いて作製されており、円筒状抵抗発熱体上における誘導円形コイル直下の誘導加熱領域の幅を狭くするためのシールドリングを兼ねるようにすることが望ましい。この場合、誘導円形コイルに対する環状冷却ジャケットの位置関係が調整可能な構成にすることがより望ましい。
【００１２】
上記した軸状被加熱物の加熱装置の円筒状抵抗発熱体は、より好ましくは、放熱し易い箇所の付近の部分の厚みがそれ以外の部分に比べて薄くするようにすることが望ましい。
【００１３】
【発明の実施の形態】
以下、本発明の実施の形態を図面を参照して説明する。図１は第１の実施の形態を説明するための図であって、（Ａ）は軸状被加熱物の加熱装置の模式的構成図、（Ｂ）は軸状被加熱物の軸方向の温度パターンを示す図である。
【００１４】
第１の実施の形態に係る軸状被加熱物の加熱装置は図１に示すような構成となっている。同装置は、軸状被加熱物Ｗの全体をその周りから間接的に加熱するカーボン製の円筒状抵抗発熱体１０と、円筒状抵抗発熱体１０を不活性ガス（ここでは窒素ガス等を用いている）下に置くために円筒状抵抗発熱体１０を収容する透明の石英菅１と、石英菅１外に配置されており且つ円筒状抵抗発熱体１０をその周りから誘導加熱する誘導円形コイル２０と、誘導円形コイル２０を円筒状抵抗発熱体１０及び石英菅１に沿って連続的に移動させる移動機構３０とを備えている。最も特徴的であるのは、円筒状抵抗発熱体１０を予め直接抵抗加熱したときの温度に比べて高い温度に誘導円形コイル２０を用いて部分的に誘導加熱させ、この状態で移動機構３０を動作させ、これを通じて軸状被加熱物Ｗ上の最高温度領域を軸方向に連続的に推移させる基本構成になっている点である。以下、各部の詳細について説明する。
【００１５】
円筒状抵抗発熱体１０は、軸状被加熱物Ｗに比べて大きな内径を有した円筒体であって、ここでは軸状被加熱物Ｗに比べて若干長いものが用いられている。円筒状抵抗発熱体１０の外表面上の上端、下端付近には、商用周波数の単相電流を生成する電源５０に接続するための給電端子１１、１２が設けられている。給電端子１１、１２は円筒状抵抗発熱体１０の全体に均一した電流が流れるように図１中に示すように円筒状抵抗発熱体１０の軸芯を基準とした対称位置に配置されている。
【００１６】
円筒状抵抗発熱体１０としてカーボン製のものを用いたのは、低温域から高温域にかけての電気的特性が優れており、誘導円形コイル２０により誘導加熱が行われても何ら支障がないので、同装置には最も理想的な発熱体だからである。ここでは軸状被加熱物Ｗを１０００℃以上の高温で熱処理することを想定しており、このような高温で大気中に置いたときには酸化して厚みが薄くなるとともに寿命が極端に短くなることから、ここでは石英菅１の中に配置している。石英菅１内には窒素等の不活性ガスが流されている。
【００１７】
なお、石英菅１の内の空気を抜いて軸状被加熱物Ｗを減圧下で熱処理するようにしてもかまわない。また、円筒状抵抗発熱体１０自体の材質や軸状被加熱物Ｗの熱処理温度との関係で、円筒状抵抗発熱体１０が容易に酸化しないときには石英菅１を省略するようにしても良い。
【００１８】
誘導円形コイル２０は、円筒状抵抗発熱体１０の外径に比べて少し大きな内径を有した環状体であって、ここでは銅製のパイプを円状に湾曲して作製されたものを用いている。移動機構３０に連結された状態で、高周波電源３０に電気接続されるとともに図外の冷却用配管に接続されている。冷却用配管を通じて供給された冷却水が誘導円形コイル２０の内部を流通してその温度上昇が防止されている。
【００１９】
移動機構３０はボールネジ機構やモータが組み合わされたものであって、モータの回転運動をボールネジ機構により直線運動に変換し、誘導円形コイル２０を図示矢印方向に移動させる構成となっている。
【００２０】
高周波電源４０は円筒状抵抗発熱体１０を誘導加熱するための数十ＫＨｚの高周波電流を生成するインバータ電源であって、高周波電流を誘導円形コイル２０に供給するようになっている。
【００２１】
なお、移動機構３０、高周波電源４０及び電源５０に対してシーケンス制御を行うシーケンサ等については図示省略されている。
【００２２】
以下、同装置の動作について説明する。まず、円筒状抵抗発熱体１０の内部に軸状被加熱物Ｗを配置する。この状態で、図外のスイッチがオンにされると、電源５０が動作する。この結果、円筒状抵抗発熱体１０が通電され発熱し（直接抵抗加熱）、円筒状抵抗発熱体１０の輻射により軸状被加熱物Ｗが加熱される（間接抵抗加熱）。即ち、軸状被加熱物Ｗの予備加熱が行われる。このときの軸状被加熱物１０の温度をＴ１（図１（Ｂ）参照）とし、円筒状抵抗発熱体１０の温度をＴ１’（Ｔ１’＞Ｔ１）とする。
【００２３】
円筒状抵抗発熱体１０に通電してから所定時間経過後に高周波電源４０が動作する。この結果、誘導円形コイル２０に高周波電流が供給され、円筒状抵抗発熱体１０のうち誘導円形コイル２０に対向した部分の周辺が誘導加熱される。このときの軸状被加熱物Ｗの当該部分の周辺の温度をＴ２（Ｔ２＞Ｔ１）とし（図１（Ｂ）参照。）、円筒状抵抗発熱体１０の当該部分の周辺の温度をＴ２’（Ｔ２’＞Ｔ２）とする。このように円筒状抵抗発熱体１０を予め直接抵抗加熱したときの温度Ｔ１’に比べて高い温度（Ｔ２’）に誘導円形コイル２０により部分的に誘導加熱される。
【００２４】
その後、誘導円形コイル２０に高周波電流が供給された状態で、高周波電源４０が動作してから所定時間経過後に移動機構３０が動作する。この結果、誘導円形コイル２０が円筒状抵抗発熱体１０に沿って図示矢印の方向に連続的に移動する。すると、円筒状抵抗発熱体１０上の最高温度領域（温度Ｔ２’）が軸方向に連続的に推移する。これに伴って、軸状被加熱物Ｗの最高温度領域（温度Ｔ２）が軸方向に連続的に推移する。よって、軸状被加熱物Ｗに対して所望の熱処理（を行うことが可能になる。ここでいう熱処理として、例えば、光ファイバ母材の焼結上の処理等がある。しかも従来装置による場合とは異なり、たとえ誘導円形コイル２０に大電流を流したとしても、その構造上、特別な絶縁設計を施す必要がない。
【００２５】
なお、高周波電源４０や移動機構３０を動作させるタイミング、誘導円形コイル２０を移動させる速度、その移動のパターン等については、軸状被加熱物Ｗ及び円筒状抵抗発熱体１０の熱容量等を考慮して適宜設定すれば良い。また、移動機構３０により円筒状抵抗発熱体１０を軸状被加熱物Ｗとともに誘導円形コイル２０に対して移動させるようにしても良い。さらに、電源５０、高周波電源４０及び移動機構３０を一斉に動作させるようにしても良い。これらの点は後述する第２の実施の形態についても同様である。
【００２６】
次に、第１の実施の形態の変形例を図２を参照して説明する。図２（Ａ）は軸状被加熱物の加熱装置の模式的構成図、（Ｂ）は軸状被加熱物の軸方向の温度パターンを示す図である。
【００２７】
この変形例においては、シールドリング７０が誘導円形コイル２０の反移動方向側の付近に配設されており、移動機構３０を用いてシールドリング７０を円筒状抵抗発熱体１０に対して誘導円形コイル２０とともに移動させるようにしている。
【００２８】
シールドリング７０は、誘導円形コイル２０と略同じ大きさの環状体であって、ここでは銅製のパイプを円状に湾曲して作製されたものを用いており、移動機構３０に取り付けられている。具体的には、ボルト等を用いて機構移動機構３０に位置調整可能に取り付けられている。これにより誘導円形コイル２０に対する環状冷却ジャケット６０の位置関係、ここではシールドリング７０と誘導円形コイル２０との距離間隔が各々調整可能になっている。
【００２９】
シールドリング７０は、誘導円形コイル２０の近くの上方位置に配置されていることから、この付近の電磁界の広がりが抑制され、そのため円筒状抵抗発熱体１０上における誘導円形コイル２０直下の誘導加熱領域の幅が狭くなり、温度パターンの山が急峻になって改善される（図２（Ｂ）参照）。この点で軸状被加熱物Ｗに対して一層望ましい熱処理を行うことが可能になる。また、軸状被加熱物Ｗの軸方向の温度パターンについては、誘導円形コイル２０に対するシールドリング７０の位置関係の調整を通じて微調整することが可能であり、この点でも所望の熱処理を行う上でメリットがある。
【００３０】
次に、第１の実施の形態の別の変形例を図３を参照して説明する。図３は軸状被加熱物の加熱装置のうち円筒状抵抗発熱体の断面図である。
【００３１】
給電端子１１、１２には熱伝導の高い銅製の配線ラインが接続されるので、円筒状抵抗発熱体１０’のうち給電端子１１、１２の付近が一番放熱し易いと言える。この変形例においては、円筒状抵抗発熱体１０’のうち放熱し易い箇所、即ち、給電端子１１、１２の付近の部分１１１、１１２の厚みがそれ以外の部分に比べて薄くされている。円筒状抵抗発熱体１０’には均一に電流が流れるものの、厚みの薄くされた部分は他の部分に比べて発熱量が大きくなるので、結果として、予熱加熱時の円筒状抵抗発熱体１０’、ひいては軸状被加熱物Ｗの軸方向の温度パターンが均一化される。
【００３２】
このように予熱加熱時の軸状被加熱物Ｗの軸方向の温度パターンが均一である状態の下で、上記したように誘導円形コイル２０により円筒状抵抗発熱体１０’の誘導加熱が行われ、軸状被加熱物Ｗの最高温度領域（温度Ｔ２）が軸方向に連続的に推移することになる。即ち、温度Ｔ２が常に安定し、この点で軸状被加熱物Ｗに対して一層望ましい熱処理を行うことが可能になる。
【００３３】
なお、上記変形例においては、円筒状抵抗発熱体１０’の内周面を切り欠いて部分１１１、１１２としたが、その代わりに外周面に同様の切り欠くようにしてもかまわない。また、円筒状抵抗発熱体１０’の内周面のうち温度の低い部分に切り欠きを形成する代わりに、温度が高い部分の内周面又は外周面に突起を形成するようにしてもかまわない。この場合であっても円筒状抵抗発熱体１０’の当該部分の断面積が大きくなり、発熱量が他の部分に比べて低下する結果、上記と全く同様の結果が得られる。
【００３４】
以下、第２の実施の形態を図４を参照して説明する。図４（Ａ）は軸状被加熱物の加熱装置の模式的構成図、（Ｂ）は軸状被加熱物の軸方向の温度パターンを示す図である。
【００３５】
第２の実施の形態に係る軸状被加熱物の加熱装置は図４に示すような構成となっている。即ち、軸状被加熱物Ｗの全体をその周りから間接的に加熱する円筒状抵抗発熱体１０’’と、円筒状抵抗発熱体１０’’をその周りから誘導加熱する誘導円形コイル２０と、誘導円形コイル２０の反移動方向側の付近に配設され且つ円筒状抵抗発熱体に向けてその周りから冷却媒体を噴射する環状冷却ジャケット６０と、誘導円形コイル２０及び環状冷却ジャケット６０を円筒状抵抗発熱体１０’’に沿って連続的に移動させる移動機構３０とを備えている。そして、円筒状抵抗発熱体１０’’を予め直接抵抗加熱したときの温度に比べて高い温度に誘導円形コイル２０を用いて部分的に誘導加熱させ、この状態で移動機構３０及び環状冷却ジャケット６０を動作させ、これを通じて軸状被加熱物Ｗ上の最高温度領域を軸方向に連続的に推移させる構成となっている。第１の実施の形態と同一部品については同一の部品番号を用いて表して説明を省略し、異なる部分を中心として以下説明する。
【００３６】
第２の実施の形態においては、冷却ガスを円筒状抵抗発熱体１０’’に直接噴射させていることから、円筒状抵抗発熱体１０’’等を石英菅１に入れた状態で加熱することは困難である。そのため、ここでは円筒状抵抗発熱体１０’’として大気中で１０００℃以上の高温に耐え得る二珪化モリブデン製（ここではＭｏＳｉ₂に鉄・クロム・アルミを添加して製造されたもの) を用いている。即ち、軸状被加熱物Ｗ及び円筒状抵抗発熱体１０’’を大気下に置き、この状態で軸状被加熱物Ｗ等を加熱するようにようにしている。
【００３７】
環状冷却ジャケット６０は、誘導円形コイル２０と略同じ大きさの環状体であって、ここでは銅製のパイプを円状に湾曲して作製されたものを用いており、誘導円形コイル２０と所定間隔を開けて平行になるように移動機構３０に取り付け付けられている。具体的には、ボルト等を用いて機構移動機構３０に位置調整可能に取り付けられており、これにより誘導円形コイル２０に対する環状冷却ジャケット６０の位置関係、ここでは環状冷却ジャケット６０と誘導円形コイル２０との距離間隔が調整可能になっている。
【００３８】
環状冷却ジャケット６０は、移動機構３０に連結された状態で図外の冷却ガス用配管に接続されている。冷却ガス用配管を通じて供給された冷却ガス（ここでは窒素ガス等）が環状冷却ジャケット６０の内部を流通し、その内面に周方向に複数形成された噴射口から冷却ガスが円筒状抵抗発熱体１０’’に向けて真っ直ぐに噴射するようになっている。
【００３９】
冷却ガス用配管の途中に設けられた図外のバルブは上記シーケンサ等により開閉制御され、移動機構３０が動作した時点で開状態にされるようになっている。そのため、円筒状抵抗発熱体１０’’に対する誘導円形コイル２０による誘導加熱と環状冷却ジャケット６０の動作による強制冷却とが同時に行われる。
【００４０】
環状冷却ジャケット６０については、誘導円形コイル２０の反移動方向側の上側付近に位置しているので、円筒状抵抗発熱体１０’’のうち誘導円形コイル２０に対向している現時点の最高温度領域ではなく、その直前の最高温度領域、言い換えると、誘導円形コイル２０が通り過ぎて温度が徐々に低下している領域に向けて冷却ガスが噴射され、当該領域が強制冷却される。これにより円筒状抵抗発熱体１０’' 上の誘導円形コイル２０直下の誘導加熱領域の幅が狭くなる。
【００４１】
しかも環状冷却ジャケット６０は電磁シールドに適した銅材を用いて作製されており、シールドリングを兼ねていることから、これにより円筒状抵抗発熱体１０’’上の誘導円形コイル２０直下の誘導加熱領域の幅が更に狭くなる。これらの結果、温度パターンの山が急峻になって改善される（図４（Ｂ）参照）。その結果、第１の実施の形態等に比べ、、軸状被加熱物Ｗに対して一層望ましい熱処理を行うことが可能になる。また、軸状被加熱物Ｗの軸方向の温度パターンについては、誘導円形コイル２０に対する環状冷却ジャケット６０の位置関係の調整を通じて微調整することが可能であり、この点でも所望の熱処理を行う上でメリットがある。ここでいう熱処理として、例えば、光ファイバ母材の焼結上の処理等がある。
【００４２】
なお、第２の実施の形態においても図３に示す例と全く同様に円筒状抵抗発熱体１０’’のうち放熱し易い箇所の厚みをそれ以外の部分に比べて薄くするようにするようにことが望ましい。
【００４３】
なお、本発明の軸状被加熱物の加熱装置は第１及び２の実施の形態に限定されず、円筒状抵抗発熱体を予め直接抵抗加熱したときの温度に比べて高い温度に誘導円形コイルを用いて部分的に誘導加熱させ、この状態で移動機構を動作させ、これを通じて軸状被加熱物上の最高温度領域を軸方向に連続的に推移させる構成となっている限り、どのような形態をとっても良く、円筒状抵抗発熱体等の構造、材質、供給電圧等については適宜設計変更すれば良い。
【００４４】
【発明の効果】
以上、本発明に係る軸状被加熱物の加熱装置による場合、軸状被加熱物上の最高温度点を軸方向に連続的に推移させることが可能な構成となっているので、軸状被加熱物に対して高品位な熱処理を施すことが可能になる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態を説明するための図であって、（Ａ）は軸状被加熱物の加熱装置の模式的構成図、（Ｂ）は軸状被加熱物の軸方向の温度パターンを示す図である。
【図２】本発明の第１の実施の形態の変形例を説明するための図であって、（Ａ）は軸状被加熱物の加熱装置の模式的構成図、（Ｂ）は軸状被加熱物の軸方向の温度パターンを示す図である。
【図３】本発明の第１の実施の別の変形例を説明するための図であって、円筒状抵抗発熱体の断面図である。
【図４】本発明の第２の実施の形態を説明するための図であって、（Ａ）は軸状被加熱物の加熱装置の模式的構成図、（Ｂ）は軸状被加熱物の軸方向の温度パターンを示す図である。
【図５】従来例を説明するための図であって、（Ａ）は軸状被加熱物の加熱装置の模式的構成図、（Ｂ）（Ｃ）は軸状被加熱物の軸方向の温度パターンを示す図である。
【符号の説明】
Ｗ軸状被加熱物
１石英菅
１０円筒状抵抗発熱体
２０誘導円形コイル
３０移動機構
４０高周波電源
５０電源[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heating apparatus for a shaft-shaped heated object that is used for heat-treating a shaft-shaped heated object.
[0002]
[Prior art]
When heat-treating the shaft-shaped object to be heated, an apparatus having a basic configuration as shown in FIG. 5A may be used. In the figure, W is a shaft-shaped object to be heated, 80 is a multi-stage heater for heating the whole of the shaft-shaped object to be heated, 90 is electric power for adjusting the amount of electric power to each of the heaters 81, 82, 83 constituting the multi-stage heater 80. It is an adjustment part. First, when alternating current is supplied to all of the heaters 81, 82, 83, the outer surface of the shaft-shaped object to be heated W is preheated. The temperature pattern in the axial direction of the shaft-shaped object W at this time is as shown in FIG. Thereafter, when the electric power applied to the heaters 81, 82, 83 is sequentially changed to the maximum in this order, the highest peak point on the outer surface of the shaft-shaped object to be heated W is shifted in order. The temperature pattern in the axial direction of the shaft-shaped object W at this time is as shown in FIG. Through such a process, the shaft-shaped object to be heated is heat-treated (a related apparatus is disclosed in Patent Document 1, for example).
[0003]
[Patent Document 1]
JP-A-6-69141 [0004]
[Problems to be solved by the invention]
Maximum However, over the heating of the shaft-like object to be heated W using a multi-stage heater 8 0 structure formed by arranging a heater 81, 82, 83 in the vertical direction, the power applied to the heater 81, 82, 83 in this order However, the maximum temperature point on the surface of the shaft-shaped heated object W is not constant in the axial direction as shown in FIG. 5C, and has a wave shape depending on the pitch interval of the heaters 81, 82, 83. Become. That is, it is impossible to continuously shift the maximum temperature point on the shaft-shaped heated object W in the axial direction, and this point is a big problem in performing desired heat treatment on the shaft-shaped heated object W. It has become.
[0005]
The present invention has been created under the above-described background, and an object of the present invention is to provide a heating apparatus for a shaft-like object to be heated that can drastically solve problems inherent in conventional apparatuses. There is.
[0006]
[Means for Solving the Problems]
A heating apparatus for a shaft-shaped object to be heated according to the present invention includes a cylindrical resistance heating element that indirectly heats the entire shaft-shaped heating object from the periphery thereof, and an induction circle that induction-heats the cylindrical resistance heating element from the periphery thereof. It has a coil and a moving mechanism that continuously moves the induction circular coil along the cylindrical resistance heating element, and induces the cylindrical resistance heating element to a temperature higher than that when the cylindrical resistance heating element is directly resistance-heated in advance. A circular coil is used for partial induction heating, and the moving mechanism is operated in this state, whereby the maximum temperature region on the axially heated object is continuously shifted in the axial direction.
[0007]
Specifically, a cylindrical resistance heating element made of carbon that indirectly heats the entire shaft-shaped object to be heated from its surroundings, and a cylindrical shape for placing the cylindrical resistance heating element under an inert gas or reduced pressure A quartz cage containing a resistance heating element, an induction circular coil arranged outside the quartz cage and induction-heating the cylindrical resistance heating element from its periphery, and the induction circular coil along the cylindrical resistance heating element and the quartz cage In this state, the cylindrical resistance heating element is partially induction-heated using an induction circular coil to a temperature higher than the temperature when the cylindrical resistance heating element is directly resistance-heated in advance. It is preferable to operate the moving mechanism so that the maximum temperature region on the shaft-shaped object to be heated is continuously shifted in the axial direction.
[0008]
Preferably, a shield ring for narrowing the width of the induction heating region directly under the induction circular coil on the cylindrical resistance heating element is disposed in the vicinity of the side opposite to the movement direction of the induction circular coil. It is desirable that the shield ring be moved relative to the cylindrical resistance heating element together with the induction circular coil. In this case, it is more desirable that the positional relationship of the shield ring with respect to the induction circular coil is adjustable.
[0009]
Another heating apparatus for a shaft-shaped object to be heated according to the present invention includes a cylindrical resistance heating element that indirectly heats the entire shaft-shaped heating object from the periphery thereof, and induction heating of the cylindrical resistance heating element from the periphery thereof. An induction circular coil, an annular cooling jacket that is disposed in the vicinity of the side opposite to the direction of movement of the induction circular coil and injects a cooling medium from the periphery toward the cylindrical resistance heating element, and the induction circular coil and the annular cooling jacket are cylindrical And a moving mechanism that continuously moves relative to the cylindrical resistance heating element, partially using an induction circular coil at a temperature higher than that when the cylindrical resistance heating element is directly resistance-heated in advance. In this state, the moving mechanism and the annular cooling jacket are operated in this state, and the maximum temperature region on the axially heated object is continuously shifted in the axial direction through this.
[0010]
Specifically, it is preferable that a cylindrical resistance heating element made of molybdenum disilicide is used.
[0011]
Preferably, the annular cooling jacket is made of a material suitable for electromagnetic shielding, and also serves as a shield ring for narrowing the width of the induction heating region immediately below the induction circular coil on the cylindrical resistance heating element. It is desirable. In this case, it is more desirable that the positional relationship of the annular cooling jacket with respect to the induction circular coil is adjustable.
[0012]
More preferably, in the cylindrical resistance heating element of the heating device for the shaft-shaped object to be heated, the thickness in the vicinity of the portion where heat is easily radiated is made thinner than the other portions.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1A and 1B are diagrams for explaining the first embodiment, in which FIG. 1A is a schematic configuration diagram of a heating device for a shaft-shaped heated object, and FIG. 1B is an axial view of the shaft-shaped heated material. It is a figure which shows a temperature pattern.
[0014]
The heating apparatus for a shaft-shaped object to be heated according to the first embodiment has a configuration as shown in FIG. The apparatus uses a cylindrical resistance heating element 10 made of carbon that indirectly heats the entire shaft-shaped object W, and an inert gas (in this case, nitrogen gas or the like). A transparent quartz cage 1 for accommodating the cylindrical resistance heating element 10 to be placed underneath, and an induction circular coil disposed outside the quartz cage 1 and induction-heating the cylindrical resistance heating element 10 from its surroundings 20 and a moving mechanism 30 for continuously moving the induction circular coil 20 along the cylindrical resistance heating element 10 and the quartz cage 1. The most characteristic feature is that the induction heating coil 10 is partially induction-heated to a temperature higher than the temperature when the cylindrical resistance heating element 10 is directly resistance-heated in advance, and the moving mechanism 30 is moved in this state. This is a basic configuration in which the maximum temperature region on the shaft-shaped object W is continuously moved in the axial direction through operation. Details of each part will be described below.
[0015]
The cylindrical resistance heating element 10 is a cylindrical body having a larger inner diameter than that of the shaft-shaped heated object W, and here, one having a slightly longer length than that of the shaft-shaped heated object W is used. Near the upper end and the lower end on the outer surface of the cylindrical resistance heating element 10, feed terminals 11 and 12 are provided for connection to a power source 50 that generates a single-phase current having a commercial frequency. The feeding terminals 11 and 12 are arranged at symmetrical positions with respect to the axial center of the cylindrical resistance heating element 10 as shown in FIG. 1 so that a uniform current flows through the entire cylindrical resistance heating element 10.
[0016]
The reason why the cylindrical resistance heating element 10 is made of carbon is that the electrical characteristics from the low temperature range to the high temperature range are excellent, and there is no problem even if induction heating is performed by the induction circular coil 20. This is because it is the most ideal heating element for the device. Here, it is assumed that the shaft-shaped object W is heat-treated at a high temperature of 1000 ° C. or higher, and when it is placed in the atmosphere at such a high temperature, the thickness is reduced and the life is extremely shortened. Therefore, it is arranged in the quartz cage 1 here. An inert gas such as nitrogen is allowed to flow in the quartz cage 1.
[0017]
Note that the air in the quartz bowl 1 may be removed and the shaft-shaped object W may be heat-treated under reduced pressure. Further, the quartz rod 1 may be omitted when the cylindrical resistance heating element 10 is not easily oxidized due to the material of the cylindrical resistance heating element 10 itself and the heat treatment temperature of the shaft-shaped object W.
[0018]
The induction circular coil 20 is an annular body having an inner diameter that is slightly larger than the outer diameter of the cylindrical resistance heating element 10, and here, a circular pipe made of copper is used. . In a state of being coupled to the moving mechanism 30, it is electrically connected to the high frequency power supply 30 and is connected to a cooling pipe (not shown). The cooling water supplied through the cooling pipe is circulated through the induction circular coil 20 to prevent the temperature from rising.
[0019]
The moving mechanism 30 is a combination of a ball screw mechanism and a motor, and is configured to convert the rotational motion of the motor into a linear motion by the ball screw mechanism and to move the induction circular coil 20 in the direction of the arrow shown in the figure.
[0020]
The high frequency power source 40 is an inverter power source that generates a high frequency current of several tens of KHz for induction heating the cylindrical resistance heating element 10, and supplies the high frequency current to the induction circular coil 20.
[0021]
Note that a sequencer that performs sequence control on the moving mechanism 30, the high-frequency power source 40, and the power source 50 is not shown.
[0022]
Hereinafter, the operation of the apparatus will be described. First, the shaft-shaped object W is disposed inside the cylindrical resistance heating element 10. In this state, when a switch (not shown) is turned on, the power supply 50 operates. As a result, the cylindrical resistance heating element 10 is energized to generate heat (direct resistance heating), and the axial heated object W is heated by the radiation of the cylindrical resistance heating element 10 (indirect resistance heating). That is, preheating of the shaft-shaped object to be heated W is performed. At this time, the temperature of the shaft-shaped object 10 is T1 (see FIG. 1B), and the temperature of the cylindrical resistance heating element 10 is T1 ′ (T1 ′> T1).
[0023]
The high frequency power supply 40 operates after a predetermined time has passed since the cylindrical resistance heating element 10 was energized. As a result, a high-frequency current is supplied to the induction circular coil 20 and the periphery of the portion of the cylindrical resistance heating element 10 facing the induction circular coil 20 is induction-heated. At this time, the temperature around the portion of the shaft-shaped object W is T2 (T2> T1) (see FIG. 1B), and the temperature around the portion of the cylindrical resistance heating element 10 is T2 ′. (T2 ′> T2). In this manner, the induction circular coil 20 is partially induction-heated to a temperature (T2 ′) higher than the temperature T1 ′ when the cylindrical resistance heating element 10 is directly resistance-heated in advance.
[0024]
Thereafter, the moving mechanism 30 is operated after a predetermined time has elapsed since the high-frequency power supply 40 is operated in a state where the high-frequency current is supplied to the induction circular coil 20. As a result, the induction circular coil 20 continuously moves in the direction of the arrow shown along the cylindrical resistance heating element 10. Then, the maximum temperature region (temperature T2 ′) on the cylindrical resistance heating element 10 continuously changes in the axial direction. Along with this, the maximum temperature region (temperature T2) of the shaft-shaped object to be heated W continuously changes in the axial direction. Therefore, a desired heat treatment can be performed on the shaft-shaped object W. The heat treatment here includes, for example, a treatment for sintering an optical fiber preform. In contrast, even if a large current is passed through the induction circular coil 20, there is no need for special insulation design due to its structure.
[0025]
Note that the timing for operating the high-frequency power supply 40 and the moving mechanism 30, the speed at which the induction circular coil 20 is moved, the pattern of the movement, and the like take into account the heat capacity of the shaft-shaped object W and the cylindrical resistance heating element 10 and the like. May be set as appropriate. Further, the cylindrical resistance heating element 10 may be moved with respect to the induction circular coil 20 together with the shaft-shaped object W by the moving mechanism 30. Furthermore, the power supply 50, the high frequency power supply 40, and the moving mechanism 30 may be operated simultaneously. These points are the same in the second embodiment described later.
[0026]
Next, a modification of the first embodiment will be described with reference to FIG. FIG. 2A is a schematic configuration diagram of a heating apparatus for a shaft-shaped object to be heated, and FIG. 2B is a diagram illustrating an axial temperature pattern of the shaft-shaped object to be heated.
[0027]
In this modification, the shield ring 70 is disposed in the vicinity of the induction circular coil 20 on the side opposite to the moving direction, and the moving ring 30 is used to move the shield ring 70 to the cylindrical resistance heating element 10. 20 is moved together.
[0028]
The shield ring 70 is an annular body having substantially the same size as that of the induction circular coil 20, and here, a shield pipe 70 is formed by bending a copper pipe into a circular shape, and is attached to the moving mechanism 30. . Specifically, it is attached to the mechanism moving mechanism 30 using bolts or the like so that the position can be adjusted. Thereby, the positional relationship of the annular cooling jacket 60 with respect to the induction circular coil 20, here, the distance between the shield ring 70 and the induction circular coil 20 can be adjusted.
[0029]
Since the shield ring 70 is disposed at an upper position near the induction circular coil 20, the spread of the electromagnetic field in the vicinity thereof is suppressed, so that the induction heating immediately below the induction circular coil 20 on the cylindrical resistance heating element 10 is suppressed. The width of the region is narrowed, and the peak of the temperature pattern becomes steep and is improved (see FIG. 2B). In this respect, a more desirable heat treatment can be performed on the shaft-shaped object W. Further, the temperature pattern in the axial direction of the shaft-shaped object W can be finely adjusted through adjustment of the positional relationship of the shield ring 70 with respect to the induction circular coil 20. There are benefits.
[0030]
Next, another modification of the first embodiment will be described with reference to FIG. FIG. 3 is a cross-sectional view of a cylindrical resistance heating element in a heating apparatus for a shaft-shaped object to be heated.
[0031]
Since the copper wiring lines with high heat conduction are connected to the power supply terminals 11 and 12, it can be said that the vicinity of the power supply terminals 11 and 12 among the cylindrical resistance heating elements 10 ′ is most easily radiated. In this modification, the portion of the cylindrical resistance heating element 10 ′ that easily radiates heat, that is, the portions 111 and 112 in the vicinity of the power feeding terminals 11 and 12 are made thinner than the other portions. Although the current flows uniformly through the cylindrical resistance heating element 10 ′, the heat generation amount is larger in the thinned portion than in the other parts, and as a result, the cylindrical resistance heating element 10 ′ during preheating heating. As a result, the temperature pattern in the axial direction of the shaft-shaped object to be heated W is made uniform.
[0032]
As described above, the induction heating of the cylindrical resistance heating element 10 ′ is performed by the induction circular coil 20 under the condition that the temperature pattern in the axial direction of the shaft-shaped object W during the preheating heating is uniform. The maximum temperature region (temperature T2) of the shaft-shaped heated object W continuously changes in the axial direction. That is, the temperature T2 is always stable, and in this respect, it is possible to perform a more desirable heat treatment on the shaft-shaped object W.
[0033]
In the above modification, the inner peripheral surface of the cylindrical resistance heating element 10 ′ is cut out to form the portions 111 and 112, but instead, the same cutout may be made on the outer peripheral surface. Further, instead of forming a notch in the low temperature portion of the inner peripheral surface of the cylindrical resistance heating element 10 ', a protrusion may be formed on the inner peripheral surface or the outer peripheral surface of the high temperature portion. . Even in this case, the cross-sectional area of the portion of the cylindrical resistance heating element 10 ′ is increased, and the amount of heat generation is reduced as compared with the other portions. As a result, the same result as above can be obtained.
[0034]
Hereinafter, the second embodiment will be described with reference to FIG. FIG. 4A is a schematic configuration diagram of a heating apparatus for a shaft-shaped object to be heated, and FIG. 4B is a diagram illustrating an axial temperature pattern of the shaft-shaped object to be heated.
[0035]
The heating apparatus for a shaft-shaped object to be heated according to the second embodiment has a configuration as shown in FIG. That is, a cylindrical resistance heating element 10 ″ that indirectly heats the entire shaft-shaped object W from its periphery, an induction circular coil 20 that induction-heats the cylindrical resistance heating element 10 ″ from its periphery, An annular cooling jacket 60 that is disposed in the vicinity of the induction circular coil 20 on the side opposite to the moving direction and injects a cooling medium toward the cylindrical resistance heating element, and the induction circular coil 20 and the annular cooling jacket 60 are cylindrical. And a moving mechanism 30 that continuously moves along the resistance heating element 10 ″. The cylindrical resistance heating element 10 '' is partially induction-heated using the induction circular coil 20 to a temperature higher than the temperature when the resistance heating is directly performed in advance, and in this state, the moving mechanism 30 and the annular cooling jacket 60 are heated. The maximum temperature region on the shaft-shaped heated object W is continuously shifted in the axial direction through this. The same parts as those in the first embodiment are denoted by the same part numbers and the description thereof is omitted, and different parts are mainly described below.
[0036]
In the second embodiment, since the cooling gas is directly injected onto the cylindrical resistance heating element 10 ″, heating is performed while the cylindrical resistance heating element 10 ″ and the like are placed in the quartz cage 1. It is difficult. Therefore, here, the cylindrical resistance heating element 10 ″ is made of molybdenum disilicide (here, manufactured by adding iron, chromium, and aluminum to MoSi ₂₎ capable of withstanding high temperatures of 1000 ° C. or more in the atmosphere. ing. That is, the shaft-shaped object W and the cylindrical resistance heating element 10 '' are placed in the atmosphere, and the shaft-shaped object W and the like are heated in this state.
[0037]
The annular cooling jacket 60 is an annular body having substantially the same size as that of the induction circular coil 20, and is formed by bending a copper pipe into a circular shape, and is spaced from the induction circular coil 20 at a predetermined interval. It is attached to the moving mechanism 30 so as to open and become parallel. Specifically, it is attached to the mechanism moving mechanism 30 using bolts or the like so that the position can be adjusted. Thereby, the positional relationship of the annular cooling jacket 60 with respect to the induction circular coil 20, here, the annular cooling jacket 60 and the induction circular coil 20. The distance between and can be adjusted.
[0038]
The annular cooling jacket 60 is connected to a cooling gas pipe (not shown) while being connected to the moving mechanism 30. A cooling gas (here, nitrogen gas or the like) supplied through the cooling gas pipe flows through the inside of the annular cooling jacket 60, and the cooling gas is supplied to the cylindrical resistance heating element 10 from a plurality of injection holes formed in the circumferential direction on the inner surface thereof. It is designed to spray straight toward ''.
[0039]
A valve (not shown) provided in the middle of the cooling gas pipe is controlled to be opened and closed by the sequencer or the like, and is opened when the moving mechanism 30 is operated. Therefore, the induction heating by the induction circular coil 20 and the forced cooling by the operation of the annular cooling jacket 60 are simultaneously performed on the cylindrical resistance heating element 10 ″.
[0040]
Since the annular cooling jacket 60 is positioned near the upper side of the induction circular coil 20 on the side opposite to the moving direction, the current highest temperature region facing the induction circular coil 20 in the cylindrical resistance heating element 10 ''. Instead, the cooling gas is injected toward the highest temperature region immediately before it, in other words, the region where the induction circular coil 20 passes and the temperature gradually decreases, and the region is forcibly cooled. As a result, the width of the induction heating region immediately below the induction circular coil 20 on the cylindrical resistance heating element 10 '' is reduced.
[0041]
In addition, since the annular cooling jacket 60 is made of a copper material suitable for electromagnetic shielding and also serves as a shield ring, this causes induction heating directly under the induction circular coil 20 on the cylindrical resistance heating element 10 ″. The width of the region is further narrowed. As a result, the peak of the temperature pattern becomes steep and is improved (see FIG. 4B). As a result, it is possible to perform a more desirable heat treatment on the shaft-shaped object to be heated W compared to the first embodiment or the like. Further, the temperature pattern in the axial direction of the shaft-shaped object W can be finely adjusted through adjustment of the positional relationship of the annular cooling jacket 60 with respect to the induction circular coil 20, and in this respect as well, a desired heat treatment can be performed. There is merit in. Examples of the heat treatment herein include a process for sintering an optical fiber preform.
[0042]
Also in the second embodiment, the thickness of the portion that easily radiates heat in the cylindrical resistance heating element 10 '' is made thinner than the other portions, just like the example shown in FIG. It is desirable.
[0043]
In addition, the heating apparatus for the axially heated object of the present invention is not limited to the first and second embodiments, and the induction circular coil is heated to a temperature higher than the temperature when the cylindrical resistance heating element is directly resistance-heated in advance. As long as it has a configuration in which the maximum temperature region on the shaft-shaped object to be heated is continuously shifted in the axial direction through partial induction heating using this, operating the moving mechanism in this state, It may take a form, and the design, structure, material, supply voltage, etc. of the cylindrical resistance heating element etc. may be changed as appropriate.
[0044]
【The invention's effect】
As described above, in the case of the heating apparatus for a shaft-shaped object to be heated according to the present invention, the maximum temperature point on the shaft-shaped object to be heated can be continuously shifted in the axial direction. High-quality heat treatment can be performed on the heated object.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram for explaining a first embodiment of the present invention, in which (A) is a schematic configuration diagram of a heating device for a shaft-shaped object to be heated, and (B) is a shaft-shaped object to be heated. It is a figure which shows the temperature pattern of this axial direction.
FIGS. 2A and 2B are diagrams for explaining a modification of the first embodiment of the present invention, in which FIG. 2A is a schematic configuration diagram of a heating apparatus for a shaft-shaped object to be heated, and FIG. It is a figure which shows the temperature pattern of the axial direction of a to-be-heated material.
FIG. 3 is a view for explaining another modification of the first embodiment of the present invention, and is a cross-sectional view of a cylindrical resistance heating element.
FIGS. 4A and 4B are diagrams for explaining a second embodiment of the present invention, in which FIG. 4A is a schematic configuration diagram of a heating apparatus for a shaft-shaped object to be heated, and FIG. 4B is a shaft-shaped object to be heated; It is a figure which shows the temperature pattern of this axial direction.
FIGS. 5A and 5B are diagrams for explaining a conventional example, in which FIG. 5A is a schematic configuration diagram of a heating apparatus for an axially heated object, and FIGS. 5B and 5C are axial views of the axially heated object. It is a figure which shows a temperature pattern.
[Explanation of symbols]
W shaft-shaped object to be heated 1 quartz rod 10 cylindrical resistance heating element 20 induction circular coil 30 moving mechanism 40 high-frequency power supply 50 power supply

Claims

A cylindrical resistance heating element that indirectly heats the entire shaft-shaped object to be heated from its periphery, an induction circular coil that induction-heats the cylindrical resistance heating element from its periphery, and the induction circular coil as a cylindrical resistance heating element And a moving mechanism for continuous relative movement along the cylindrical resistance heating element, using a circular induction coil to partially inductively heat the cylindrical resistance heating element to a temperature higher than that when the direct resistance heating is performed in advance. An apparatus for heating an axially heated object, wherein the moving mechanism is operated in a state and the maximum temperature region on the axially heated object is continuously shifted in the axial direction through the moving mechanism.

Accommodates a cylindrical resistance heating element made of carbon that indirectly heats the entire shaft-shaped object to be heated, and a cylindrical resistance heating element for placing the cylindrical resistance heating element under an inert gas or reduced pressure A quartz cage, an induction circular coil that is arranged outside the quartz cage and induction-heats the cylindrical resistance heating element from its periphery, and the induction circular coil is continuously relative to the cylindrical resistance heating element and the quartz cage. It is equipped with a moving mechanism that moves, and the induction heating coil is partially induction-heated to a temperature higher than the temperature when the cylindrical resistance heating element is directly resistance-heated in advance, and the moving mechanism operates in this state. A heating apparatus for a shaft-shaped object to be heated is characterized in that the maximum temperature region on the shaft-shaped object to be heated is continuously shifted in the axial direction.

3. A heating apparatus for a shaft-shaped object to be heated according to claim 1 or 2, wherein the shield ring for narrowing the width of the induction heating region immediately below the induction circular coil on the cylindrical resistance heating element is on the side opposite to the moving direction of the induction circular coil. The apparatus for heating a shaft-shaped object to be heated is characterized in that the shield ring is moved relative to the cylindrical resistance heating element together with the induction circular coil by using a moving mechanism. .

4. The heating apparatus for a shaft-shaped object to be heated according to claim 3, wherein the positional relationship of the shield ring with respect to the induction circular coil is adjustable.

Cylindrical resistance heating element that indirectly heats the entire shaft-shaped object to be heated from its periphery, an induction circular coil that induction-heats the cylindrical resistance heating element from its periphery, and the vicinity of the anti-movement direction side of the induction circular coil And an annular cooling jacket for injecting a cooling medium toward the cylindrical resistance heating element and a moving mechanism for continuously moving the induction circular coil and the annular cooling jacket along the cylindrical resistance heating element. In this state, the cylindrical resistance heating element is partially induction-heated using an induction circular coil to a temperature higher than the temperature when the resistance heating body is directly resistance-heated in advance, and the moving mechanism and the annular cooling jacket are operated in this state. A heating apparatus for a shaft-shaped object to be heated is characterized in that the maximum temperature region on the shaft-shaped object to be heated is continuously shifted in the axial direction.

6. The heating apparatus for a shaft-shaped object to be heated according to claim 5, wherein a cylindrical resistance heating element made of molybdenum disilicide is used.

7. The heating apparatus for a shaft-shaped object to be heated according to claim 5, wherein the annular cooling jacket is made of a material suitable for an electromagnetic shield, and is an induction heating region directly under the induction circular coil on the cylindrical resistance heating element. A heating device for a shaft-shaped object to be heated, which also serves as a shield ring for narrowing the width of the shaft.

The heating apparatus for a shaft-shaped object to be heated according to claim 5, 6 or 7, wherein the positional relationship of the annular cooling jacket with respect to the induction circular coil is adjustable. apparatus.

9. A heating apparatus for a shaft-shaped object to be heated according to claim 1, wherein the cylindrical resistance heating element has a thinner portion near a portion where heat is easily radiated than other portions. A heating device for a shaft-shaped object to be heated.