JP3548524B2

JP3548524B2 - High frequency induction heating coil

Info

Publication number: JP3548524B2
Application number: JP2000394274A
Authority: JP
Inventors: 秀明片沼
Original assignee: Denki Kogyo Co Ltd
Current assignee: Denki Kogyo Co Ltd
Priority date: 2000-12-26
Filing date: 2000-12-26
Publication date: 2004-07-28
Anticipated expiration: 2020-12-26
Also published as: JP2002194425A

Description

【０００１】
【発明の属する技術分野】
本発明は、第１及び第２の段部を有する段付き軸状部材（多段付き軸状部材）を焼入処理等のために高周波誘導加熱するための高周波誘導加熱コイルに関するものである。
【０００２】
【従来の技術】
等速ジョイントのアウターレースやインボードジョイント等の部品として、段付き軸状部材が用いられている。この種の段付き軸状部材はエンジンの回転を車輪に伝達する重要保安部品であるため、強度についての要求が厳しく、特に段部における隅部（隅Ｒ部とも称される）はねじり疲労強度破壊の起点になる箇所であることから、隅部における焼入硬化層の焼入深さが重要視されている。
【０００３】
図５は、第１及び第２の（２段の）段部１ａ，１ｂを有する段付き軸状部材２を示すものである。この種の段付き軸状部材２は、図５示すように、相対的に大きな直径を有する大径軸部３と、この大径軸部３と同軸状に設けられた相対的に小さな直径を有する小径軸部４とをそれぞれ備え、大径軸部３と小径軸部４との境界箇所に第１及び第２の段部１ａ，１ｂが設けられている。なお、第２の段部１ｂは、相対的に小径の軸部分に設けられており、前記小径軸部４の付け根部分の隅部（隅Ｒ部）５ｂと、この隅部５ｂに連なる座面部６ｂと、この座面部６ｂに連なる肩部７ｂにて構成されている。また、第１の段部１ａは、相対的に大径の軸部分に設けられており、前記肩部７ｂに連なる隅部（隅Ｒ部）５ａと、この隅部５ａに連なる座面部６ａと、この座面部６ａに連なる肩部７ａにて構成されている。このような段付き軸状部材２については、小径軸部４の表面から第１及び第２の段部１ａ，１ｂの表面に連続する均一な焼入硬化層パターン（焼入深さは、例えば２．０〜５．５ｍｍ程度）を要求される。
【０００４】
また、図６は、上述の段付き軸状部材２を焼入するために従来より用いられている高周波誘導加熱コイル１０を示すものである。この高周波誘導加熱コイル１０は、図６に示すように、段付き軸状部材２（小径軸部４）の軸線Ｐを中心に１８０゜隔てた位置で段付き軸状部材２の小径軸部４の周面に平行に対向配置される直線形状の２本の小径軸部加熱導体１１，１２と、これらの小径軸部加熱導体１１，１２にそれぞれ接続され、かつ、段付き軸状部材２の軸線Ｐに対して直角に配置されると共に第２の段部１ｂの座面部６ｂに平行に対応配置される直線形状の２本の段部加熱導体（第１の段部加熱導体）１３，１４と、これらの段部加熱導体１３，１４にそれぞれ接続され、かつ、段付き軸状部材２の軸線Ｐを中心に１８０゜隔てた位置で前記軸線Ｐに対して平行な状態で第１の段部１ａの肩部７ａと第２の段部１ｂの隅部５ｂとの間の軸部部分に対応配置される直線形状の２本の周面加熱導体１５，１６と、これらの周面加熱導体１５，１６の間に接続され、かつ、第２の段部１ｂの座面部６ｂに対して平行な状態でこの座面部６ｂの半円弧部分に沿って対応配置される半円弧形状の段部加熱導体（第２の段部加熱導体）１７とから構成されている。なお、図６において、１８，１９は図外の高周波電源から電流を供給するためのリード導体であり、これらのリード導体１８，１９間には図７及び図８に示す如く絶縁板２０が介在されるようになっている。
【０００５】
かくして、段付き軸状部材２を焼入処理するに際しては、高周波誘導加熱コイル１０にて取り囲まれた領域内に被焼入体である段付き軸状部材２の半分部分を配置し、図９に示す如く高周波誘導加熱コイル１０と段付き軸状部材２との間に所定の間隔を保った状態の下で段付き軸状部材２をその軸線Ｐを中心に回転させながら高周波誘導加熱コイル１０に高周波電流を流すことにより、段付き軸状部材２の小径軸部４、第２の段部１ｂの隅部５ｂ，座面部６ｂ及び肩部７ｂ、並びに第１の段部１ａの隅部５ａ，座面部６ａｂ及び肩部７ａの表面を高周波誘導加熱する。次いで、高周波誘導加熱された段付き軸状部材２の加熱部分を冷却液にて急冷することにより、これらの部分の表面に連続する焼入硬化層を形成するようにしている。
【０００６】
ところで、図９に示すように、焼入硬化層の焼入深さが最も重要視される段付き軸状部材の第２の段部１ｂの隅部５ｂの誘導加熱は、柱状の小径軸部加熱導体１１，１２及び棒状の段部加熱導体１３，１４に流される高周波電流の誘導作用により段付き軸状部材２の軸線Ｐに対して直角な方向に誘導電流が発生することによりなされると共に、段付き軸状部材の第１の段部１ａの隅部５ａの誘導加熱は、半円弧形状の段部加熱導体１７に流れる高周波電流の誘導作用により段付き軸状部材２の軸線Ｐに対して直角な方向に誘導電流が発生することによりなされる。なお、段付き軸状部材２の小径軸部４、隅部５ａ，５ｂ、及び座面部６ａ，６ｂのうちで隅部５ａ，５ｂは特に誘導加熱されずらく、小径軸部４と座面部６ａ，６ｂが誘導加熱されるのに伴って小径軸部４と座面部６ａ，６ｂとからの熱伝導により昇温する割合が多い。因みに、座面部６ａ，６ｂは、小径軸部４に対して加熱効率が約７０％と低いので、前記隅部５ａ，５ｂにおける焼入硬化層パターンを深くして強度の向上を図るためには、座面部６ａ，６ｂに誘導加熱を集中させる必要がある。
【０００７】
そこで、従来では、段付き軸状部材２の隅部５ａ，５ｂの部分は磁束の関係から特に誘導加熱されにくい箇所であるため、高周波誘導加熱コイル１０の特定部分、すなわち第１の段部加熱導体１３，１４及び第２の段部加熱導体１７にダストコアや珪素鋼板等の磁性材（磁束集中材）２１をそれぞれ取付けて隅部５ａ，５ｂに磁束を集中させて隅部５ａ，５ｂの加熱効率を向上させるようにしているのが実状である。
【０００８】
【発明が解決しようとする課題】
しかしながら、磁性材２１は、誘導加熱すべき段付き軸状部材２に対して数ｍｍ程度の間隔をもって離れた位置に配置された状態で高周波誘導加熱が行われるため、高周波誘導加熱された段付き軸状部材２からの輻射熱を強く受ける。その結果、段付き軸状部材２の加熱処理本数が増すのに伴い磁性材２１が輻射熱の影響により熱変形すると共に、焦げ付き等の不具合を生じる場合がある。また、磁性材２１の劣化により焼入硬化層パターンが不良になるおそれがある。
【０００９】
図１１は劣化した磁性材２１を示しており、コ字形状の磁性材２１のうち被加熱体である段付き軸状部材２に最も接近した部分Ｍ，Ｎが過熱による劣化（熱影響）を最も顕著に生じる。熱影響を大きく受けた磁性材２１では磁束を集中させる効果が弱くなり、これに伴い、磁性材２１に対応する段付き軸状部材２の近傍箇所における焼入硬化層パターンが不良となる。すなわち、図５及び図９に示すように、隅部５ａ，５ｂの焼入硬化層Ｓ_１，Ｓ_２の深さが小径軸部４の焼入硬化層Ｓ_３の深さに対して浅くなり、小径軸部４から第２の段部１ｂを介して第１の段部１ａに連なる表面上に均一な焼入硬化層パターンＳを形成することができず、これに起因して強度（特に、ねじり疲労強度）を充分に満足できないような不具合を生じる。
【００１０】
なお、焼入硬化層パターンＳが隅部５ａ，５ｂにおいて浅くなるような不具合を解消するための手段としては、既述の如く座面部６ａを高周波誘導加熱する棒状の段部加熱導体１３，１４に珪素鋼板やダストコア等の磁性材２１をより多く取付けたり、段部加熱導体１３，１４と座面部６ｂとの間の間隔Ｇ（図１０参照）を狭くすることによって、座面部６ｂの加熱効率（ひいては隅部５ｂの加熱効率）を増大させることが考えられるが、このような手段を採用したとしても座面部６ｂについての加熱効率の向上の程度に限界があり、第２の段部１ｂの隅部５ｂ付近における焼入硬化層Ｓ_２の深さを小径軸部４における焼入硬化層Ｓ_３の深さほどに深くすることができないのが実状である。また、段部加熱導体１７に珪素鋼板やダストコア等の磁性材２２を配設しても第１の段部１ａの隅部５ａに関しては充分に深い焼入硬化層Ｓ_１（図１０参照）を得ることができないのが実状である。
【００１１】
また、第１の段部１ａでけでなく第２の段部１ｂにも一連の（一続きの）焼入硬化層パターンＳを形成する場合には、特に、第１の段部１ａの隅部５ａと第２の段部１ｂの隅部５ｂの熱容量を考慮してこれらの加熱バランスを良好に保ちながら、小径軸部４と段差（幅）が相対的に広い座面部６ｂとの間にある第２の段部１ｂの隅部５ｂにおける焼入硬化層Ｓ_２の深さ、並びに、第１の段部１ａの隅部５ｂにおける焼入硬化層Ｓ_１の深さを充分に確保する必要がある。
【００１２】
本発明は、以上の如き種々の実状に鑑みてなされたものであって、その目的は、ダストコアや珪素鋼板等の磁性材（磁束集中材）を加熱導体に取付けなくても、段付き軸状部材の小径軸部から第１及び第２の段部に連なる表面上に均一な焼入硬化層パターンを形成し得るように均一加熱を行うことができるような高周波誘導加熱コイルを提供することにある。
【００１３】
上述の目的を達成するために、本発明では、相対的に大きな直径を有する大径軸部と、相対的に小さな直径を有する小径軸部と、前記大径軸部と小径軸部との間にそれぞれ形成される第１及び第２の段部とをそれぞれ備えた段付き軸状部材を高周波誘導加熱するための高周波誘導加熱コイルにおいて、
（ａ）相対的に大径の軸部分に設けられる前記第１の段部に対応配置される円弧形状の第１の段部加熱導体と、
（ｂ）前記第１の段部加熱導体に接続されると共に、相対的に小径の軸部分に設けられる前記第２の段部に対応配置される円弧形状の第２の段部加熱導体と、
（ｃ）前記第２の段部加熱導体に接続されると共に、前記小径軸部の軸線に対して平行な状態で前記小径軸部に対応配置される直線形状の第１の小径軸部加熱導体と、
（ｄ）前記第１の小径軸部加熱導体に接続されると共に、加熱されるべき前記小径軸部の周面のうちで前記大径軸部から最も離れた位置における第１の周面部分に対応配置される円弧形状の第２の小径軸部加熱導体と、
（ｅ）前記第２の小径軸部加熱導体に接続されて前記第２の小径軸部加熱導体に対向するように設けられると共に、加熱されるべき前記小径軸部の周面のうちで前記大径軸部から最も離れた位置と前記大径軸部との間の位置において前記第１の周面部分に対向する第２の周面部分に対応配置される円弧形状の第３の小径軸部加熱導体と、
をそれぞれ備え、
前記第１及び第２の段部加熱導体を含む１巻きの巻線部分と、前記第１，第２及び第３の小径部加熱導体を含む１巻きの巻線部分とを構成し、全体としては一続きの２巻きの巻線構造として構成し、
前記第１の小径軸部加熱導体を、前記小径軸部の軸線方向における前記第２及び第３の小径軸部加熱導体間の隙間部分に対応する箇所を通るように配置すると共に、
前記第１の段部加熱導体の円弧の長さαと前記第２の段部加熱導体の円弧の長さβとの関係を、α≧βとなるように設定するようにしている。
また、本発明では、前記条件α≧βを満足することを前提として、前記第１の段部加熱導体の円弧の中心角θ₁を６０°≦θ₁≦３００°の範囲で設定し、かつ、第２の段部加熱導体の円弧の中心角θ₂を６０°≦θ₂≦２００°の範囲で設定するようにしている。
また、本発明では、コイル構成体である加熱導体の何れの部分にもダストコアや珪素鋼板等の磁性材を取付けないようにしている。
【００１４】
このような構成の本発明の高周波誘導加熱コイルによれば、相対的に小径の軸部分に設けられる第２の段部を直接加熱する加熱導体として円弧形状の第２の段部加熱導体を使用することにより、小径軸部よりも第２の段部への加熱効率が増大される。また、小径軸部に対応して直線形状（柱形状）の第１の小径軸部加熱導体及び円弧形状の第２及び第３の小径軸部加熱導体を使用することにより、小径軸部の軸線方向における第２及び第３の小径軸部加熱導体間の隙間部分（継ぎ目部分）においても直線形状の第１の小径軸部加熱導体により誘導加熱が行われるため、小径軸部の表面に形成される焼入硬化層パターンは均一な深さの滑らかなものとなる。また、第１の段部加熱導体の円弧の長さαを第２の段部加熱導体の円弧の長さβよりも長く設定することにより（α≧β）、熱容量が互いに異なる第１及び第２の段部における加熱バランスが良好となり、第１及び第２の段部をそれぞれ構成する隅部，座面部及び肩部に連続した均一深さの焼入硬化層パターンが形成される。かくして、第１及び第２の隅部における焼入硬化層は従来の場合よりも深く形成され、これにより、第１の段部から第２の段部を介して小径軸部のまで繋がる段付き軸状部材の表面に連続した均一な硬化層パターンが形成される。さらに、高周波誘導加熱コイルの巻き数を２巻き（第１及び第２の段部加熱導体で１巻き、第１，第２及び第３の小径軸部加熱導体で１巻き）とし、第１及び第２の段部加熱導体の円弧の長さを第２及び第３の小径軸部加熱導体の円弧の長さよりも長くすることにより、熱容量が相対的大きい第１及び第２の段部に加熱が集中される。また、高周波誘導加熱コイルの巻き数を２巻きにしたことにより、従来の１巻きコイルよりも加熱効率が上げられることとなり、従ってダストコアや珪素鋼板等の磁性材を使用しなくても第１及び第２の隅部における焼入硬化層の深さが充分に確保される。
【００１５】
【発明の実施の形態】
以下、本発明の一実施形態について図１〜図４を参照して説明する。なお、図１〜図４において、図５〜図１１と同様の部分には同一の符号を付して重複する説明を省略する。
【００１６】
図１は、本発明の一実施形態に係る高周波誘導加熱コイル３０を示している。この高周波誘導加熱コイル３０は、段付き軸状部材２の焼入処理時に段付き軸状部材２の小径軸部４、第１の段部１ａ及び第２の段部１ｂを高周波誘導加熱するために使用されるものである。図１に示すように、高周波誘導加熱コイル３０は、一続きのコイル構成体から成る導電性の部品であって、高周波電源３１に接続された一対のリード導体３２ａ，３２ｂと、これらのうちの一方のリード導体３２ａに接続されると共に、段付き軸状部材２のうちの相対的に大径の軸部分に設けられる第１の段部１ａに対応配置される円弧形状の第１の段部加熱導体３３と、この第１の段部加熱導体３３に連結導体３４，３５を順次に介して接続されると共に、段付き軸状部材２のうちの相対的に小径の軸部分に設けられる第２の段部１ｂに対応配置される円弧形状の第２の段部加熱導体３６と、この第２の段部加熱導体３６に接続されると共に、段付き軸状部材２（小径軸部４）の軸線Ｐに対して平行な状態で小径軸部４に対応配置される直線形状の第１の小径軸部加熱導体３７と、この第１の小径軸部加熱導体３７に接続されると共に、加熱されるべき小径軸部４の周面のうちで大径軸部３から最も離れた第１の周面部分Ｒ₁（図３参照）に対応配置される円弧形状の第２の小径軸部加熱導体３８と、この第２の小径軸部加熱導体３８に接続された連結導体３９と前記リード導体３２ｂとの間に接続されると共に、加熱されるべき小径軸部４の周面のうちで前記第１の周面部分Ｒ₁よりも下方の第２の周面部分Ｒ₂（図３参照）に対応配置される円弧形状の第３の小径軸部加熱導体４０（すなわち、加熱されるべき小径軸部４の周面のうちで大径軸部３から最も離れた位置と大径軸部３との間の位置において第１の周面部分に対向する第２の周面部分に対応配置される円弧形状の第３の小径軸部加熱導体４０）とから構成されている。そして、上述の第３の小径軸部加熱導体４０は、図１及び図２に示すように、前記第２の小径軸部加熱導体３８に対して対向するように設けられている。
【００１７】
なお、第１及び第２の段部加熱導体３３，３６と連結導体３４，３５とで１巻きの巻線が構成されると共に、第１，第２及び第３の小径部加熱導体３７，３８，４０と連結導体３９とで１巻きの巻線が構成され、全体としては一続きの２巻きの巻線構造（互いに直列接続されたシリイスな２巻きの巻線構造）として構成されている。すなわち、高周波誘導加熱コイル３０の巻き数は、第１及び第２の段部加熱導体３３，３６を含む１巻き部分と、第１，第２及び第３の小径軸部加熱導体３８，４０を含む１巻き部分とで２巻きの構造となされている。また、上述の一対のリード導体３２ａ，３３ａ間には、図２に示すように絶縁板４１が介在されている。なお、図２において、３２ａ_−１，３２ａ_−２はリード導体３２ａを構成するリード導体部分であり、３２ｂ_−１，３２ｂ_−２はリード導体３２ｂを構成するリード導体部分である。
【００１８】
図１における矢印は、ある瞬間に高周波誘導加熱コイル３０に流れる電流の通電方向を示しており、この際には、高周波電流が高周波電源３１からリード導体３２ａ、第１の段部加熱導体３３、連結導体３４，３５、第２の段部加熱導体３６、第１の小径軸部加熱導体３７、第２の小径軸部加熱導体３８、連結導体３９、第３の小径軸部加熱導体４０、及びリード導体３２ｂを順次に流れ、次の瞬間にはこれとは逆の方向に高周波電流が交互に流れるようになっている。
【００１９】
また、上述の高周波誘導加熱コイル３０にあっては、図２に示すように、段付き軸状部材２の第１の段部１ａに対応配置されてこの段部１ａを高周波誘導加熱する第１の段部加熱導体３３の円弧の長さ（周長）αと、段付き軸状部材２の第２の段部１ｂに対応配置されてこの段部１ｂを高周波誘導加熱する第２の段部加熱導体３６の円弧の長さ（周長）βとの相互間の関係は、α≧βとなるように設定されている。また、熱容量が小径軸部４よりも相対的に大きい第１及び第２の段部１ａ，１ｂに加熱を集中させるために、第１及び第２の段部加熱導体３３，３６の全体としての円弧の長さは、第２及び第３の小径軸部加熱導体３８，４０の全体としての円弧の長さよりも長く設定されている。なお、図２におけるθ_１及びθ_２は、第１の段部加熱導体３３及び第２の段部加熱導体３６の円弧の中心角である。
【００２０】
一方、本実施形態の高周波誘導加熱コイル３０では、ダストコアや珪素鋼板等の磁性材（磁束集中材）が何れの加熱導体部分（特に、第１及び第２の段部加熱導体３３，３６並びに第１，第２及び第３の小径部加熱導体３７，３８、４０）にも取付けられておらず、従って加熱導体（コイル構成体）のみにて構成されている。
【００２１】
このような構成の高周波誘導加熱コイル３０を用いて段付き軸状部材２の２段の段部１ａ，１ｂの表面を焼入処理すると、良好な焼入硬化層パターンを得ることができる。具体的には、高周波誘導加熱コイル３０の軸線と段付き軸状部材２の軸線Ｐとが互いに一致するように配置してこれらの間に所定の隙間を保った状態の下で段付き軸状部材２をその軸線Ｐを中心に回転させながら高周波誘導加熱を行ない、その直後に冷却液にて急冷すると、小径軸部４から第２の段部１ｂを介して第１の段部１ａに至るまでの表面領域に一続きの均一な焼入硬化層パターン（強度についての最重要部である第１及び第２の隅部５ａ，５ｂにおいて充分な深さを有する焼入硬化層パターン）Ｓを形成することができる。その理由を述べると、次の通りである。
【００２２】
まず、図３に示すように、第１の段部１ａの座面部６ａは第１の段部加熱導体３３により直接に誘導加熱されると共に、第２の段部１ｂの座両部６ｂは、第２の段部加熱導体３６により直接に誘導加熱される。また、小径軸部４の立ち上がり部（付け根部）４ａは、第２の段部加熱導体３６に流れる段付き軸状部材２の軸線Ｐを中心とする円周方向の高周波電流、及び、第１の小径軸部導体３７に流れる前記軸線Ｐに平行な高周波電流により誘導加熱される。そのため、小径軸部４の立ち上がり部４ａの加熱が促進されて第２の段部１ｂの隅部５ｂが充分に加熱される。その結果、図４に示す如く、前記隅部５ｂに充分な深さの焼入硬化層Ｓ_２を形成することができ、ひいては小径軸部４の周面から前記隅部５ｂを介して第２の段部１ｂの座面部６ｂに至るまでの表面領域に均一で滑らかな焼入硬化層パターンＳを得ることができる。
【００２３】
さらに、小径軸部４の誘導加熱は、第１，第２及び第３の小径軸部加熱導体３７，３８，４０に流される高周波電流により行われると共に、軸線Ｐに平行な方向（軸線方向）における第２及び第３の小径軸部加熱導体３８，４０間の隙間部分（図３に示す継ぎ目部分）Ｌに対応する箇所を通るように直線形状の第１の小径軸部加熱導体３７が配置されるため、この第１の小径軸部加熱導体３７を流れる軸線方向の高周波電流にて前記隙間部分Ｌに対応する小径軸部４の対応部分が誘導加熱され、これにより前記対応部分の誘導加熱が促進されるため滑らかに連続する均一な焼入硬化層を得ることができる。
【００２４】
また、熱容量のバランスを考慮して、既述の如く、軸径が相対的に大きい第１の段部１ａを誘導加熱する第１の段部加熱導体３３の円弧の長さαを、軸径が相対的に小さい第２の段部１ｂを誘導加熱する第２の段部加熱導体３６の円弧の長さβよりも長く設定するようにしているので（α≧β）、第１の段部１ａ（大径部）よりも第２の段部１ｂ（小径部）への高周波誘導加熱が相対的に増大される。そのため、熱容量が相対的に大きい第１の段部１ａと熱容量が相対的に小さい第２の段部１ｂとにおける相対的な加熱バランスが良くなり、従って均一に誘導加熱されて均一な焼入硬化層パターン（特に、第１及び第２の段部１ａ，１ｂの隅部５ａ，５ｂに充分な深さの焼入硬化層を有する焼入硬化層パターン）を得ることができる。
【００２５】
かくして、上述の如き構成を有する本実施形態の高周波誘導加熱コイル３０によれば、このコイル３０を構成する加熱導体（コイル導体）にダストコアや珪素鋼板等の磁性材を取付けることなく、小径軸部４から第２の段部１ｂを介して第１の段部１ａへと繋がる均一な深さの焼入硬化層パターンＳを得ることができる。特に、加熱すべき段付き軸状部材２の各部の加熱バランスが良好となることにより、強度についての最重要部である第１及び第２の隅部５ａ，５ｂを充分に加熱できてこれらの隅部５ａ，５ｂに充分な深さの焼入硬化層を形成することができる。従って、第１及び第２の段部１ａ，１ｂの隅部５ａ，５ｂにおける焼入硬化層が深くなることにより、段付き軸状部材２の耐久性（特に、ねじり疲労強度）に最も影響する最重要部である隅部５ａ，５ｂの強度を上げることができ、ひいては段付き軸状部材２の耐久性の向上を図ることができる。
【００２６】
以下に、本発明の一実施形態の具体的な実施例を示す。
実施例
（１）ワーク：ＢＪアウターレース
（ａ）材質：Ｓ５３Ｃ
（ｂ）軸部寸法： φ２８ｍｍ
（ｃ）肩部寸法： φ５６ｍｍ
（２）高周波誘導加熱コイル
（ａ）第１の段部加熱導体の円弧の長さα ：２６２ｍｍ
（ｂ）第１の段部加熱導体の円弧の中心角θ_１：２７０゜
（ｃ）第２の段部加熱導体の円弧の長さβ ：１２２ｍｍ
（ｄ）第２の段部加熱導体の円弧の中心角θ_２：１８０゜
（ｅ）第１の小径軸部加熱導体の長さ：３４ｍｍ
（ｆ）第２の小径軸部加熱導体の円弧の長さγ：９４ｍｍ
（ｇ）第２の小径軸部加熱導体の円弧の中心角θ_３：１３５゜
（ｈ）第３の小径軸部加熱導体の円弧の長さδ：１０７ｍｍ
（ｇ）第３の小径軸部加熱導体の円弧の中心角θ_４：１３５゜
（３）高周波誘導加熱条件
（ａ）周波数：８ｋＨｚ
（ｂ）出力：１７５ｋＷ
（ｃ）加熱時間：４．５ｓｅｃ
（ｄ）回転数：１２０ｒｐｍ
（４）冷却条件
（ａ）冷却液：ユーコンクエンチャントＡ（８％）
（ｂ）液温：３０℃
（ｃ）流量：１５０ｌ／ｍｉｎ
（ｅ）冷却時間：１５ｓｅｃ
【００２７】
上記の加工条件により段付き軸部２の焼入処理を施した場合の焼入硬化層の深さは、小径軸部３（スプライン付け根部）において４．２ｍｍ、第１及び第２の隅部５ａ，５ｂにおいて３．２ｍｍであった。なお、従来の高周波誘導加熱コイル１０を用いて段付き軸部２の焼入処理を施した場合の焼入硬化層の深さは、小径軸部４において５．５ｍｍ、第１及び第２の隅部５ａ，５ｂにおいて１．８ｍｍであった。従って、本発明の高周波誘導加熱コイル３０によれば、小径軸部３における焼入硬化層Ｓ_３の深さが相対的に浅くなると共に、第１及び第２の隅部５ａ，５ｂにおける焼入硬化層Ｓ_１，Ｓ_２の深さが相対的に深くなるため、焼入硬化層深さの全体としてのバランスが良くなって焼入硬化層パターンの深さを均一化することができることが確認された。
【００２８】
また、第１の段部加熱導体３３の円弧の中心角θ_１及び第２の段部加熱導体３６の円弧の中心角θ_２（図２参照）を適宜に変えて焼入硬化層パターンのデータをとったところ、既述の条件式α≧βを満たすことを前提として、第１の段部加熱導体３３の円弧の中心角θ_１については６０゜≦θ_１≦３００゜の範囲で設定し、かつ、第２の段部加熱導体３６の円弧の中心角θ_２については６０゜≦θ_２≦２００゜の範囲で設定した場合に、上述の如き効果を最も顕著に得ることができることが判明した。
【００２９】
以上、本発明の一実施形態について述べたが、本発明はこの実施形態に限定されるものではなく、本発明の技術的思想に基づいて各種の変形及び変更が可能である。例えば、第１の段部加熱導体３３と第２の段部加熱導体３６との間の接続部、及び、第２の小径軸部加熱導体３８と第３の小径軸部加熱導体４０との間の接続部の構成は任意に変更可能である。
【００３０】
【発明の効果】
請求項１に記載の本発明は、全体として２巻きの巻線構造に構成すると共に、段付き軸状部材の小径軸部の軸線に対して平行な状態でこの小径軸部に対応配置される直線形状の第１の小径軸部加熱導体を、加熱されるべき小径軸部の周面のうちで大径軸部から最も離れた第１の周面部分に対応配置される円弧形状の第２小径軸部加熱導体と、加熱されるべき小径軸部の周面のうちで大径軸部から最も離れた位置と前記大径軸部との間の位置において第１の周面部分に対向する第２の周面部分に対応配置される円弧形状の第３の小径軸部加熱導体（円弧形状の第２の小径軸部加熱導体に対向するように設けられた、小径軸部加熱用として追加された加熱導体）との間の前記小径軸部の軸線方向における隙間部分に対応する箇所を通るように配置すると共に、相対的に大径の軸部分に設けられる第１の段部に対応配置される円弧形状の第１の段部加熱導体の円弧の長さ（周長）αと、相対的に小径の軸部分に設けられる第２の段部に対応配置される円弧形状の第２の段部加熱導体の円弧の長さ（周長）βとの関係を、α≧βとなるように設定するようにしたものであるから、全体として２巻きの巻線構造としかつ第３の小径軸部加熱導体を追加したことに伴い加熱交率の向上を図ることができることに加え、小径軸部のうちの前記隙間部分に対応する部分が第１の小径軸部加熱導体にて誘導加熱されるので小径軸部の表面にその軸線方向に沿って均一な深さの焼入硬化層を形成することができると共に、α≧βの設定により、軸径が相対的に小さくて熱容量が相対的に小さい部分である第２の段部よりも、軸径が相対的に大きくて熱容量が相対的に大きい部分である第１の段部への加熱を増大せしめることができ、ひいては第１の段部から第２の段部を介して小径軸部に繋がる表面領域の各部における加熱バランスを良好にすることができる。
【００３１】
その結果、小径軸部に対して第１及び第２の段部のそれぞれの隅部における加熱効率を増すことができ、第１及び第２の段部から小径軸部に繋がる表面部分に連続して均一な焼入硬化層パターンを得ることができる。そのため、本発明の高周波誘導加熱コイルによれば、ダストコアや珪素鋼板等の磁性材（磁束集中材）を使用する必要がなくなり、加熱導体のみで構成しただけの簡素な構成の安価な高周波誘導加熱コイルで済ますことが可能となる。また、磁性材を加熱導体に使用しないで済むことに伴い、磁性材の劣化により焼入硬化層パターンが不良となる等の問題の発生を回避することができる。
【００３２】
さらに、本発明の高周波誘導加熱コイルを用いて段付き軸部を高周波焼入すると、第１及び第２の段部の隅部における焼入硬化層深さを充分に深くすることができるので、段付き軸状部材の強度（特に、ねじり疲労強度）を上げることができる。
【００３３】
また、請求項２に記載の本発明は、前記条件式α≧βを満たすことを前提として、第１の段部加熱導体の円弧の中心角θ_１を６０゜≦θ_１≦３００゜の範囲で設定し、かつ、第２の段部加熱導体の円弧の中心角θ_２を６０゜≦θ_２≦２００゜の範囲で設定したものであるから、これらの条件の下に前記長さα及びβを設定して焼入処理することにより、実用上の要求強度を満足する段付き軸状部材を提供することができる。
【００３４】
また、請求項３に記載の本発明は、コイル構成体である加熱導体の何れの部分にもダストコアや珪素鋼板等の磁性材を取付けないようにしたものであるから、均一な焼入硬化層パターンを得ることができるという実用上の作用効果を奏し得るものでありながら、磁性材の省略により構成が簡素でかつ安価な高周波誘導加熱コイルを提供することができる。しかも、磁性材の熱変形や焦げ付き等の不具合を生じることがなく、磁性材の劣化に伴って焼入硬化層パターンが不良になるような不具合の発生を回避することができる。
【００３５】
また、請求項４に記載の本発明は、第１及び第２の段部加熱導体を含む１巻きの巻線部分と、第１，第２及び第３の小径部加熱導体を含む１巻きの巻線部分とを構成し、全体としては一続きの（シリイスの）２巻きの巻線構造として構成するようにしたものであるから、加熱導体の巻線構造は直列巻線の簡素な構成で済み、製作が容易でしかも実用に適した高周波誘導加熱コイルを提供することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る高周波誘導加熱コイルを示す斜視図である。
【図２】図１に示す高周波誘導加熱コイルの平面図である。
【図３】図１に示す高周波誘導加熱コイルにて段付き軸状部材を焼入処理のために高周波誘導加熱する際の状態を示す断面図である。
【図４】図１に示す高周波誘導加熱コイルを用いて焼入処理した場合に段付き軸状部材の表面に形成される焼入硬化層パターンを示す断面図である。
【図５】被加熱体である段付き軸状部材を示す断面図である。
【図６】従来の高周波誘導加熱コイルを示す斜視図である。
【図７】図６に示す高周波誘導加熱コイルの平面図である。
【図８】図６に示す高周波誘導加熱コイルの正面図である。
【図９】図６に示す高周波誘導加熱コイルにて段付き軸状部材を焼入処理のために高周波誘導加熱する際の状態を示す断面図である。
【図１０】図６に示す高周波誘導加熱コイルに磁性材を取付けて焼入処理した場合に段付き軸状部材の表面に形成される焼入硬化層パターンを示す断面図である。
【図１１】高周波誘導加熱コイルに取付けられる磁性材の斜視図である。
【符号の説明】
１ａ第１の段部
１ｂ第２の段部
２段付き軸状部材
３大径軸部
４小径軸部
４ａ立ち上がり部（付け根部）
５ａ第１の隅部
５ｂ第２の隅部
６ａ第１の座面部
６ｂ第２の座面部
７ａ第１の肩部
７ｂ第２の肩部
３０高周波誘導加熱コイル
３３第１の段部加熱導体
３６第２の段部加熱導体
３７第１の小径軸部加熱導体
３８第２の小径軸部加熱導体
４０第３の小径軸部加熱導体
Ｌ隙間部分（継ぎ目部分）
Ｒ_１第１の周面
Ｒ_２第２の周面
Ｓ焼入硬化層パターン
α 第１の段部加熱導体の円弧の長さ
β 第２の段部加熱導体の円弧の長さ
θ_１第１の段部加熱導体の円弧の中心角
θ_２第２の段部加熱導体の円弧の中心角
θ_３第２の小径軸部加熱導体の円弧の中心角
θ_４第３の小径軸部加熱導体の円弧の中心角[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-frequency induction heating coil for high-frequency induction heating of a stepped shaft member (multi-stepped shaft member) having first and second step portions for quenching processing or the like.
[0002]
[Prior art]
A stepped shaft-like member is used as a component such as an outer race or an inboard joint of a constant velocity joint. Since this type of stepped shaft member is an important security component that transmits the rotation of the engine to the wheels, the requirements for strength are strict. Particularly, the corners (also referred to as corners R) of the steps are torsional fatigue strength. It is important to consider the quenching depth of the quench-hardened layer at the corners, since it is the starting point of fracture.
[0003]
FIG. 5 shows a stepped shaft-like member 2 having first and second (two steps) step portions 1a and 1b. As shown in FIG. 5, this type of stepped shaft member 2 has a large diameter shaft portion 3 having a relatively large diameter and a relatively small diameter provided coaxially with the large diameter shaft portion 3. The first and second steps 1a and 1b are provided at the boundary between the large-diameter shaft 3 and the small-diameter shaft 4 respectively. The second step portion 1b is provided on a shaft portion having a relatively small diameter, and a corner portion (corner R portion) 5b of a root portion of the small diameter shaft portion 4 and a seat surface portion connected to the corner portion 5b 6b and a shoulder 7b connected to the seating surface 6b. The first step 1a is provided on a shaft portion having a relatively large diameter, and has a corner (corner R) 5a connected to the shoulder 7b, and a seat surface 6a connected to the corner 5a. And a shoulder portion 7a connected to the seat surface portion 6a. For such a stepped shaft-like member 2, a uniform quench hardened layer pattern (the quenching depth is, for example, continuous from the surface of the small-diameter shaft portion 4 to the surfaces of the first and second step portions 1 a and 1 b). 2.0 to 5.5 mm).
[0004]
FIG. 6 shows a high-frequency induction heating coil 10 conventionally used for quenching the stepped shaft member 2 described above. As shown in FIG. 6, the high-frequency induction heating coil 10 has a small-diameter shaft portion 4 of the stepped shaft-like member 2 at a position 180 ° away from the axis P of the stepped shaft-like member 2 (small-diameter shaft portion 4). The two small-diameter shaft-portion heating conductors 11 and 12 which are disposed opposite to each other in parallel to the peripheral surface of the shaft, and are connected to these small-diameter shaft-portion heating conductors 11 and 12, respectively, and Two linear step heating conductors (first step heating conductors) 13, 14 which are arranged at right angles to the axis P and correspondingly arranged in parallel with the bearing surface 6b of the second step 1b. And a first step connected to the step heating conductors 13 and 14 and parallel to the axis P at a position 180 ° away from the axis P of the stepped shaft member 2. A straight portion corresponding to the shaft portion between the shoulder portion 7a of the portion 1a and the corner portion 5b of the second step portion 1b. The two peripheral heating conductors 15 and 16 having a shape are connected between the peripheral heating conductors 15 and 16 and are parallel to the bearing surface 6b of the second step portion 1b. And a semi-circular step heating conductor (second step heating conductor) 17 correspondingly arranged along the semi-arc portion of the surface portion 6b. In FIG. 6, reference numerals 18 and 19 denote lead conductors for supplying a current from a high-frequency power source (not shown), and an insulating plate 20 is interposed between these lead conductors 18 and 19 as shown in FIGS. It is supposed to be.
[0005]
Thus, when the stepped shaft member 2 is subjected to the quenching treatment, a half portion of the stepped shaft member 2 which is the quenched body is arranged in a region surrounded by the high-frequency induction heating coil 10, and FIG. As shown in FIG. 5, the high-frequency induction heating coil 10 is rotated while rotating the stepped shaft member 2 about its axis P while maintaining a predetermined distance between the high-frequency induction heating coil 10 and the stepped shaft member 2. The high-frequency current is applied to the small-diameter shaft portion 4 of the stepped shaft-like member 2, the corner 5b of the second step 1b, the seat surface 6b and the shoulder 7b, and the corner 5a of the first step 1a. The surface of the seat surface 6ab and the surface of the shoulder 7a are subjected to high-frequency induction heating. Next, the heated portions of the stepped shaft-like member 2 that have been subjected to the high-frequency induction heating are rapidly cooled with a cooling liquid to form a continuous hardened hardened layer on the surfaces of these portions.
[0006]
By the way, as shown in FIG. 9, the induction heating of the corner 5b of the second step portion 1b of the stepped shaft-like member in which the quenching depth of the quenching hardened layer is most important is performed by the columnar small-diameter shaft portion. The induction current is generated in a direction perpendicular to the axis P of the stepped shaft member 2 by the induction action of the high-frequency current flowing through the heating conductors 11 and 12 and the rod-shaped step heating conductors 13 and 14. The induction heating of the corner 5a of the first step portion 1a of the stepped shaft-like member is performed with respect to the axis P of the stepped shaft-like member 2 by the induction action of the high-frequency current flowing through the semicircular step heating conductor 17. This is done by generating an induced current in a direction perpendicular to the direction. The corners 5a and 5b of the small-diameter shaft 4, the corners 5a and 5b, and the seats 6a and 6b of the stepped shaft-shaped member 2 are particularly difficult to be induction-heated, so that the small-diameter shaft 4 and the seat 6a are hardly heated. , 6b are heated by induction from the small-diameter shaft portion 4 and the seating portions 6a, 6b with induction heating. Incidentally, since the heating efficiency of the seating surfaces 6a and 6b is as low as about 70% with respect to the small-diameter shaft 4, the quenching-hardened layer pattern at the corners 5a and 5b is deepened to improve the strength. In addition, it is necessary to concentrate induction heating on the seat surfaces 6a and 6b.
[0007]
Therefore, conventionally, since the corners 5a and 5b of the stepped shaft-like member 2 are particularly difficult to be induction-heated due to the relation of magnetic flux, a specific portion of the high-frequency induction heating coil 10, that is, the first stepped portion is heated. A magnetic material (magnetic flux concentration material) 21 such as a dust core or a silicon steel plate is attached to the conductors 13 and 14 and the second step heating conductor 17 to concentrate magnetic flux on the corners 5a and 5b to heat the corners 5a and 5b. The reality is that we are trying to improve efficiency.
[0008]
[Problems to be solved by the invention]
However, since the high frequency induction heating is performed in a state where the magnetic material 21 is arranged at a position spaced apart from the stepped shaft-shaped member 2 to be induction heated by about several mm, the high frequency induction heated stepped Radiation heat from the shaft member 2 is strongly received. As a result, as the number of heat treatments of the stepped shaft-like member 2 increases, the magnetic material 21 may be thermally deformed by the influence of radiant heat and may cause a problem such as scorching. Further, there is a possibility that the quenched hardened layer pattern becomes defective due to the deterioration of the magnetic material 21.
[0009]
FIG. 11 shows the deteriorated magnetic material 21, and the portions M and N of the U-shaped magnetic material 21 which are closest to the stepped shaft-like member 2, which is the object to be heated, deteriorate due to overheating (thermal influence). Most notably occurs. The effect of concentrating the magnetic flux is weakened in the magnetic material 21 greatly affected by the heat, and accordingly, the quenched hardened layer pattern in the vicinity of the stepped shaft member 2 corresponding to the magnetic material 21 becomes defective. That is, as shown in FIGS. 5 and 9, the quench hardened layer S at the corners 5a and 5b is formed.₁, S₂Hardening layer S of small diameter shaft part 4₃And a uniform quench-hardened layer pattern S cannot be formed on the surface connected to the first step portion 1a from the small-diameter shaft portion 4 via the second step portion 1b, This causes a problem that the strength (particularly, torsional fatigue strength) cannot be sufficiently satisfied.
[0010]
As a means for solving the problem that the quench hardened layer pattern S becomes shallow at the corners 5a and 5b, as described above, the bar-shaped step heating conductors 13 and 14 for high-frequency induction heating the seating surface 6a are used. By mounting more magnetic material 21 such as a silicon steel plate or a dust core on the surface, or reducing the gap G (see FIG. 10) between the step heating conductors 13 and 14 and the seating surface 6b, the heating efficiency of the seating surface 6b is increased. Although it is conceivable to increase the heating efficiency of the corner 5b, the degree of improvement of the heating efficiency of the seating surface 6b is limited even if such a means is adopted, and the second step 1b has a limited heating efficiency. Quench hardened layer S near corner 5b₂Hardening layer S in small diameter shaft portion 4₃The fact is that it cannot be made as deep as the depth of the. Even if the magnetic material 22 such as a silicon steel plate or a dust core is disposed on the step heating conductor 17, the corner 5a of the first step 1a is sufficiently deep in the quench hardened layer S.₁(See FIG. 10) cannot be obtained.
[0011]
Further, when a series of (continuous) quench hardened layer patterns S are formed not only in the first step 1a but also in the second step 1b, the corners of the first step 1a are particularly required. In consideration of the heat capacities of the portion 5a and the corner 5b of the second step portion 1b, while maintaining a good heating balance between the small-diameter shaft portion 4 and the seating surface portion 6b having a relatively wide step (width). Quench hardened layer S at corner 5b of certain second step 1b₂And the quenched hardened layer S at the corner 5b of the first step 1a₁It is necessary to secure a sufficient depth of the object.
[0012]
SUMMARY OF THE INVENTION The present invention has been made in view of the above various circumstances, and has as its object to provide a stepped shaft-like structure without attaching a magnetic material (magnetic flux concentration material) such as a dust core or a silicon steel plate to a heating conductor. To provide a high-frequency induction heating coil capable of performing uniform heating so as to form a uniform quenched and hardened layer pattern on a surface connected to the first and second steps from a small diameter shaft portion of a member. is there.
[0013]
In order to achieve the above-described object, according to the present invention, a large-diameter shaft having a relatively large diameter, a small-diameter shaft having a relatively small diameter, and a space between the large-diameter shaft and the small-diameter shaft are provided. A high-frequency induction heating coil for high-frequency induction heating of a stepped shaft member having first and second step portions respectively formed in
(A) an arc-shaped first step heating conductor arranged corresponding to the first step provided on a shaft part having a relatively large diameter;
(B) an arc-shaped second step heating conductor connected to the first step heating conductor and arranged corresponding to the second step provided on a shaft portion having a relatively small diameter;
(C) a first small-diameter shaft portion heating conductor having a linear shape connected to the second step portion heating conductor and arranged corresponding to the small-diameter shaft portion in a state parallel to the axis of the small-diameter shaft portion; When,
(D) connected to the first small-diameter shaft heating conductor, and most distant from the large-diameter shaft portion on the peripheral surface of the small-diameter shaft portion to be heatedIn positionAn arc-shaped second small-diameter shaft portion heating conductor arranged corresponding to the first peripheral surface portion;
(E) connected to the second small-diameter shaft portion heating conductor, provided so as to face the second small-diameter shaft portion heating conductor, and of the peripheral surface of the small-diameter shaft portion to be heated;At a position between the position farthest from the large-diameter shaft portion and the large-diameter shaft portionThe first peripheral portionOpposeAn arc-shaped third small-diameter shaft heating conductor arranged corresponding to the second peripheral surface portion;
Respectively,
One winding part including the first and second step heating conductors and one winding part including the first, second and third small diameter heating conductors are configured as a whole. Is configured as a continuous two-turn winding structure,
The first small-diameter shaft portion heating conductor is disposed so as to pass through a location corresponding to a gap between the second and third small-diameter shaft portion heating conductors in the axial direction of the small-diameter shaft portion,
The relationship between the arc length α of the first step heating conductor and the arc length β of the second step heating conductor is set so that α ≧ β.
Further, in the present invention, on the assumption that the condition α ≧ β is satisfied, the central angle θ of the arc of the first stepped heating conductor is set.₁Is 60 ° ≦ θ₁≤ 300 ° and the center angle θ of the arc of the second step heating conductor_TwoIs 60 ° ≦ θ_TwoIt is set within the range of ≦ 200 °.
Further, in the present invention, a magnetic material such as a dust core or a silicon steel plate is not attached to any part of the heating conductor as the coil structure.
[0014]
According to the high-frequency induction heating coil of the present invention having such a configuration, the arc-shaped second step heating conductor is used as the heating conductor for directly heating the second step provided on the shaft portion having a relatively small diameter. By doing so, the heating efficiency for the second step portion is increased more than for the small diameter shaft portion. In addition, by using the first small-diameter shaft portion heating conductor having a linear shape (a pillar shape) and the second and third small-diameter shaft portion heating conductors having an arc shape corresponding to the small-diameter shaft portion, the axis of the small-diameter shaft portion is formed. Also in the gap portion (joint portion) between the second and third small-diameter shaft portion heating conductors in the direction, the induction heating is performed by the linear first small-diameter shaft portion heating conductor, so that the gap is formed on the surface of the small-diameter shaft portion. The quench hardened layer pattern becomes smooth with a uniform depth. In addition, by setting the length α of the arc of the first step heating conductor to be longer than the length β of the arc of the second step heating conductor (α ≧ β), the first and second heat capacities different from each other are set. The heating balance in the second step is improved, and a quench-hardened layer pattern having a uniform depth is formed continuously at the corners, the seating surface, and the shoulder constituting the first and second steps. Thus, the quench-hardened layers at the first and second corners are formed deeper than in the conventional case, thereby providing a step from the first step to the small diameter shaft through the second step. A continuous and uniform cured layer pattern is formed on the surface of the shaft member. Further, the number of turns of the high-frequency induction heating coil is set to 2 (1 turn for the first and second step heating conductors, and 1 turn for the first, second and third small-diameter shaft heating conductors). By making the length of the arc of the second step heating conductor longer than the length of the arc of the second and third small diameter shaft heating conductors, the first and second steps having a relatively large heat capacity can be heated. Is concentrated. In addition, since the number of turns of the high-frequency induction heating coil is set to two, the heating efficiency can be increased as compared with the conventional one-turn coil. Therefore, the first and second coils can be used without using a magnetic material such as a dust core or a silicon steel plate. The depth of the quench hardened layer at the second corner is sufficiently ensured.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In FIGS. 1 to 4, the same parts as those in FIGS. 5 to 11 are denoted by the same reference numerals, and redundant description is omitted.
[0016]
FIG. 1 shows a high-frequency induction heating coil 30 according to one embodiment of the present invention. The high-frequency induction heating coil 30 is used for high-frequency induction heating of the small-diameter shaft portion 4, the first step portion 1a, and the second step portion 1b of the stepped shaft member 2 during the quenching process of the stepped shaft member 2. It is used for As shown in FIG. 1, the high-frequency induction heating coil 30 is a conductive component formed of a continuous coil structure, and includes a pair of lead conductors 32 a and 32 b connected to a high-frequency power supply 31, and An arc-shaped first step connected to one lead conductor 32a and arranged corresponding to a first step 1a provided on a relatively large-diameter shaft portion of the stepped shaft-like member 2 The heating conductor 33 is connected to the first step heating conductor 33 via the connecting conductors 34 and 35 sequentially, and is provided on a relatively small-diameter shaft portion of the stepped shaft member 2. A second step heating conductor 36 having an arc shape corresponding to the second step 1b, and a stepped shaft member 2 (small diameter shaft portion 4) connected to the second step heating conductor 36 and being connected to the second step heating conductor 36; Directly in correspondence with the small-diameter shaft portion 4 in a state parallel to the axis P of A first small-diameter shaft heating conductor 37 having a shape and connected to the first small-diameter shaft heating conductor 37, and the outermost surface of the small-diameter shaft 4 to be heated, which is the largest from the large-diameter shaft 3. First peripheral surface portion R away₁(See FIG. 3) A second arc-shaped second small-diameter shaft heating conductor 38 corresponding to (see FIG. 3) and a connection conductor 39 connected to the second small-diameter shaft heating conductor 38 and the lead conductor 32b The first peripheral surface portion R of the peripheral surface of the small-diameter shaft portion 4 to be connected and heated.₁Lower second peripheral surface portion R_Two(See FIG. 3) Arc-shaped third small-diameter shaft heating conductor 40 arranged corresponding to FIG.(That is, the second surface opposing the first peripheral surface portion at a position between the large-diameter shaft portion 3 and the position farthest from the large-diameter shaft portion 3 in the peripheral surface of the small-diameter shaft portion 4 to be heated. Arc-shaped third small-diameter shaft portion heating conductor 40 corresponding to the peripheral surface portion ofIt is composed of The third small-diameter shaft heating conductor 40 is provided to face the second small-diameter shaft heating conductor 38 as shown in FIGS. 1 and 2.
[0017]
The first and second step heating conductors 33 and 36 and the connection conductors 34 and 35 constitute a single-turn winding, and the first, second and third small-diameter heating conductors 37 and 38. , 40 and the connecting conductor 39 constitute a single-turn winding, and as a whole, are formed as a continuous two-turn winding structure (a series of two-turn winding structure connected in series with each other). That is, the number of turns of the high-frequency induction heating coil 30 is such that one winding portion including the first and second step heating conductors 33 and 36 and the first, second and third small-diameter shaft heating conductors 38 and 40 are provided. Including one winding part, the structure has two windings. An insulating plate 41 is interposed between the pair of lead conductors 32a and 33a as shown in FIG. In FIG. 2, 32a_-1, 32a_-2Is a lead conductor portion constituting the lead conductor 32a, and 32b_-1, 32b_-2Is a lead conductor portion constituting the lead conductor 32b.
[0018]
The arrow in FIG. 1 indicates the direction in which the current flowing in the high-frequency induction heating coil 30 at a certain moment is supplied. In this case, the high-frequency current is supplied from the high-frequency power supply 31 to the lead conductor 32a, the first step heating conductor 33, Connecting conductors 34 and 35, a second step heating conductor 36, a first small-diameter shaft heating conductor 37, a second small-diameter shaft heating conductor 38, a connecting conductor 39, a third small-diameter shaft heating conductor 40, and The high-frequency current flows alternately in the opposite direction at the next moment at the next moment.
[0019]
Further, in the above-described high-frequency induction heating coil 30, as shown in FIG. 2, a first step is provided corresponding to the first step 1a of the stepped shaft-shaped member 2 to perform high-frequency induction heating on the step 1a. Of the circular arc (perimeter) α of the step heating conductor 33 and the second step 1b of the stepped shaft-shaped member 2 for high-frequency induction heating of the step 1b. The relationship between the heating conductor 36 and the arc length (perimeter) β is set so that α ≧ β. Further, in order to concentrate the heating on the first and second steps 1a, 1b having a heat capacity relatively larger than that of the small diameter shaft section 4, the first and second steps heating conductors 33, 36 as a whole are formed. The length of the arc is set to be longer than the length of the arc as a whole of the second and third small diameter shaft heating conductors 38 and 40. Note that θ in FIG.₁  And θ₂Is the central angle of the arc of the first step heating conductor 33 and the second step heating conductor 36.
[0020]
On the other hand, in the high-frequency induction heating coil 30 of the present embodiment, the magnetic material (magnetic flux concentration material) such as a dust core or a silicon steel plate is used for any heating conductor portion (particularly, the first and second step heating conductors 33 and 36 and the second heating conductor 33 and 36). 1, the second and third small-diameter heating conductors 37, 38, and 40), and are therefore composed of only heating conductors (coil components).
[0021]
When the surfaces of the two steps 1a and 1b of the stepped shaft-like member 2 are quenched using the high-frequency induction heating coil 30 having such a configuration, a good quenched and hardened layer pattern can be obtained. Specifically, the axis of the high-frequency induction heating coil 30 and the axis P of the stepped shaft-shaped member 2 are arranged so as to coincide with each other, and a stepped shaft-like shape is formed under a state where a predetermined gap is maintained therebetween. High frequency induction heating is performed while rotating the member 2 about its axis P. Immediately thereafter, when the member 2 is rapidly cooled with a coolant, the member 2 reaches the first step portion 1a from the small diameter shaft portion 4 via the second step portion 1b. A continuous hardened hardened layer pattern S (a hardened hardened layer pattern having a sufficient depth at the first and second corners 5a and 5b, which are the most important parts for strength), is Can be formed. The reason is as follows.
[0022]
First, as shown in FIG. 3, the seating surface 6a of the first step 1a is directly induction-heated by the first step heating conductor 33, and both the seats 6b of the second step 1b are Induction heating is performed directly by the second step heating conductor 36. The rising portion (root portion) 4 a of the small-diameter shaft portion 4 includes a high-frequency current in the circumferential direction around the axis P of the stepped shaft-like member 2 flowing through the second step heating conductor 36 and the first portion. Is heated by a high-frequency current parallel to the axis P flowing through the small-diameter shaft portion conductor 37. Therefore, heating of the rising portion 4a of the small diameter shaft portion 4 is promoted, and the corner 5b of the second step portion 1b is sufficiently heated. As a result, as shown in FIG. 4, a hardened hardened layer S having a sufficient depth is formed at the corner 5b.₂And a uniform and smooth quench hardened layer pattern S on the surface area from the peripheral surface of the small diameter shaft portion 4 to the seat surface portion 6b of the second step portion 1b via the corner portion 5b. Can be obtained.
[0023]
Further, the induction heating of the small-diameter shaft portion 4 is performed by a high-frequency current flowing through the first, second, and third small-diameter shaft portion heating conductors 37, 38, and 40, and in a direction parallel to the axis P (axial direction). A first small-diameter shaft portion heating conductor 37 having a linear shape is disposed so as to pass through a portion corresponding to a gap portion (seam portion shown in FIG. 3) L between the second and third small-diameter shaft heating conductors 38 and 40 in FIG. Therefore, the corresponding portion of the small-diameter shaft portion 4 corresponding to the gap portion L is induction-heated by the high-frequency current in the axial direction flowing through the first small-diameter shaft portion heating conductor 37, whereby the induction heating of the corresponding portion is performed. Is promoted, and a smooth and continuous hardened hardened layer can be obtained.
[0024]
Further, in consideration of the balance of the heat capacity, as described above, the arc length α of the first step heating conductor 33 for induction heating the first step 1a having a relatively large shaft diameter is defined as the shaft diameter. Is set to be longer than the arc length β of the second step heating conductor 36 for induction heating the second step 1b, which is relatively small (α ≧ β). The high-frequency induction heating to the second step portion 1b (small diameter portion) is relatively increased compared to 1a (large diameter portion). Therefore, the relative heating balance between the first step portion 1a having a relatively large heat capacity and the second step portion 1b having a relatively small heat capacity is improved, so that the induction heating is uniform and the quench hardening is uniform. A layer pattern (particularly, a quench-hardened layer pattern having a quench-hardened layer with a sufficient depth at the corners 5a, 5b of the first and second steps 1a, 1b) can be obtained.
[0025]
Thus, according to the high-frequency induction heating coil 30 of the present embodiment having the above-described configuration, the small-diameter shaft portion can be mounted without attaching a magnetic material such as a dust core or a silicon steel plate to the heating conductor (coil conductor) constituting the coil 30. The quench hardened layer pattern S having a uniform depth, which is connected to the first step 1a from the step 4 through the second step 1b, can be obtained. In particular, since the heating balance of each part of the stepped shaft-shaped member 2 to be heated is improved, the first and second corners 5a and 5b, which are the most important parts for strength, can be sufficiently heated. A quench hardened layer having a sufficient depth can be formed at the corners 5a and 5b. Accordingly, the quenching hardened layers at the corners 5a, 5b of the first and second step portions 1a, 1b become deeper, which most affects the durability (particularly, torsional fatigue strength) of the stepped shaft member 2. The strength of the corners 5a and 5b, which are the most important parts, can be increased, and the durability of the stepped shaft-like member 2 can be improved.
[0026]
Hereinafter, specific examples of one embodiment of the present invention will be described.
Example
(1) Work: BJ outer race
(A) Material: S53C
(B) Shaft dimension: φ28mm
(C) Shoulder size: φ56mm
(2) High frequency induction heating coil
(A) Arc length α of first step heating conductor: 262 mm
(B) The central angle θ of the arc of the first step heating conductor₁: 270 ゜
(C) Arc length β of the second step heating conductor: 122 mm
(D) The central angle θ of the arc of the second step heating conductor₂: 180 ゜
(E) Length of first small diameter shaft portion heating conductor: 34 mm
(F) Arc length γ of the second small diameter shaft heating conductor: 94 mm
(G) The central angle θ of the arc of the second small diameter shaft heating conductor₃: 135 ゜
(H) Arc length δ of the third small diameter shaft portion heating conductor: 107 mm
(G) The central angle θ of the arc of the third small diameter shaft portion heating conductor₄: 135 ゜
(3) High frequency induction heating conditions
(A) Frequency: 8 kHz
(B) Output: 175 kW
(C) Heating time: 4.5 sec
(D) Number of revolutions: 120 rpm
(4) Cooling conditions
(A) Coolant: Yukon Quenchant A (8%)
(B) Liquid temperature: 30 ° C
(C) Flow rate: 150 l / min
(E) Cooling time: 15 sec
[0027]
When the quenching process of the stepped shaft portion 2 is performed under the above processing conditions, the depth of the quenched hardened layer is 4.2 mm in the small diameter shaft portion 3 (root portion of the spline), the first and second corners. It was 3.2 mm in 5a and 5b. When the quenching process of the stepped shaft portion 2 is performed using the conventional high-frequency induction heating coil 10, the depth of the hardened layer is 5.5 mm in the small-diameter shaft portion 4, It was 1.8 mm at the corners 5a and 5b. Therefore, according to the high-frequency induction heating coil 30 of the present invention, the hardened layer S in the small-diameter shaft portion 3 is formed.₃Is relatively shallow, and the quench hardened layer S at the first and second corners 5a and 5b is formed.₁, S₂Is relatively deep, it has been confirmed that the overall balance of the quench-hardened layer depth is improved and the quench-hardened layer pattern can have a uniform depth.
[0028]
Also, the central angle θ of the arc of the first step heating conductor 33₁And the central angle θ of the arc of the second step heating conductor 36₂The data of the quench-hardened layer pattern was obtained by appropriately changing (see FIG. 2) the center angle of the arc of the first step heating conductor 33 on the assumption that the above-mentioned conditional expression α ≧ β was satisfied. θ₁About 60 ° ≦ θ₁≦ 300 °, and the central angle θ of the arc of the second step heating conductor 36.₂About 60 ° ≦ θ₂It has been found that the above-described effects can be obtained most remarkably when the angle is set in the range of ≦ 200 °.
[0029]
As mentioned above, although one embodiment of the present invention was described, the present invention is not limited to this embodiment, and various modifications and changes are possible based on the technical idea of the present invention. For example, the connection between the first step heating conductor 33 and the second step heating conductor 36, and the connection between the second small diameter shaft heating conductor 38 and the third small diameter heating conductor 40 The configuration of the connection part can be arbitrarily changed.
[0030]
【The invention's effect】
The present invention according to claim 1 is configured to have a winding structure of two turns as a whole, and is arranged corresponding to the small diameter shaft portion in a state parallel to the axis of the small diameter shaft portion of the stepped shaft member. A linear first small-diameter shaft portion heating conductor is connected to a second arc-shaped second peripheral surface portion of the small-diameter shaft portion to be heated, which is located farthest from the large-diameter shaft portion. Of the small diameter shaft heating conductor and the peripheral surface of the small diameter shaft to be heatedOpposite to the first peripheral surface portion at a position between the position farthest from the large diameter shaft portion and the large diameter shaft portionArc-shaped third small-diameter shaft portion heating conductor (corresponding to the second arc-shaped second small-diameter shaft heating conductor, which is provided for heating the small-diameter shaft portion and is disposed corresponding to the second peripheral surface portion) (The heated heating conductor) is arranged so as to pass through a portion corresponding to a gap portion in the axial direction of the small-diameter shaft portion and a first step portion provided on a relatively large-diameter shaft portion. The length (circumferential length) of the arc of the arc-shaped first step heating conductor to be formed and the second arc-shaped second step disposed on the relatively small-diameter shaft portion Since the relationship with the arc length (perimeter) β of the step heating conductor is set so that α ≧ β, a winding structure of two turns as a whole and a third small diameter are used. The addition of the shaft heating conductor not only improves the heat exchange rate, but also reduces the diameter of the shaft. Since the portion corresponding to the gap portion is induction-heated by the first small-diameter shaft portion heating conductor, it is possible to form a quench hardened layer having a uniform depth along the axial direction on the surface of the small-diameter shaft portion. In addition, by setting α ≧ β, a portion having a relatively large shaft diameter and a relatively large heat capacity can be obtained from the second step portion, which is a portion having a relatively small shaft diameter and a relatively small heat capacity. It is possible to increase the heating to the first step portion, and thereby to improve the heating balance in each portion of the surface region connected from the first step portion to the small-diameter shaft portion via the second step portion. it can.
[0031]
As a result, the heating efficiency at the respective corners of the first and second steps can be increased with respect to the small-diameter shaft portion, and the heating efficiency is continuous with the surface portion connected from the first and second steps to the small-diameter shaft portion. And a uniform quench-hardened layer pattern can be obtained. Therefore, according to the high-frequency induction heating coil of the present invention, there is no need to use a magnetic material (a magnetic flux concentration material) such as a dust core or a silicon steel plate. It can be done with coils. In addition, since the magnetic material does not need to be used for the heating conductor, it is possible to avoid problems such as the deterioration of the hardened layer pattern due to the deterioration of the magnetic material.
[0032]
Furthermore, when the stepped shaft portion is induction hardened using the high frequency induction heating coil of the present invention, the quench hardened layer depth at the corners of the first and second step portions can be made sufficiently deep. The strength (particularly, torsional fatigue strength) of the stepped shaft member can be increased.
[0033]
The present invention described in claim 2 is based on the premise that the conditional expression α ≧ β is satisfied, and the center angle θ of the arc of the first step heating conductor is provided.₁Is 60 ° ≦ θ₁≦ 300 °, and the central angle θ of the arc of the second step heating conductor₂Is 60 ° ≦ θ₂≦ 200 °, so that the lengths α and β are set and quenched under these conditions to obtain a stepped shaft member satisfying the practically required strength. Can be provided.
[0034]
According to the third aspect of the present invention, since a magnetic material such as a dust core or a silicon steel plate is not attached to any portion of the heating conductor which is a coil structure, a uniform hardened and hardened layer is formed. A high-frequency induction heating coil having a simple structure and an inexpensive configuration can be provided by omitting the magnetic material, while achieving the practical effect of obtaining a pattern. Moreover, problems such as thermal deformation and scorching of the magnetic material do not occur, and it is possible to avoid such a problem that the hardened layer pattern becomes defective due to the deterioration of the magnetic material.
[0035]
Further, the present invention according to claim 4 provides a single winding portion including the first and second step heating conductors and a single winding portion including the first, second and third small diameter heating conductors. Since the winding part is constituted as a continuous (Siriis) two-turn winding structure as a whole, the heating conductor winding structure is a simple structure of series winding. Thus, a high-frequency induction heating coil which is easy to manufacture and suitable for practical use can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a high-frequency induction heating coil according to an embodiment of the present invention.
FIG. 2 is a plan view of the high-frequency induction heating coil shown in FIG.
FIG. 3 is a cross-sectional view showing a state when the stepped shaft-shaped member is subjected to high-frequency induction heating for quenching by the high-frequency induction heating coil shown in FIG. 1;
FIG. 4 is a cross-sectional view showing a quench-hardened layer pattern formed on the surface of the stepped shaft-shaped member when quenching is performed using the high-frequency induction heating coil shown in FIG.
FIG. 5 is a cross-sectional view showing a stepped shaft-shaped member which is a heated object.
FIG. 6 is a perspective view showing a conventional high-frequency induction heating coil.
FIG. 7 is a plan view of the high-frequency induction heating coil shown in FIG. 6;
FIG. 8 is a front view of the high-frequency induction heating coil shown in FIG. 6;
9 is a cross-sectional view showing a state when the stepped shaft-shaped member is subjected to high-frequency induction heating for quenching by the high-frequency induction heating coil shown in FIG. 6;
10 is a cross-sectional view showing a quench hardened layer pattern formed on the surface of the stepped shaft-shaped member when a magnetic material is attached to the high-frequency induction heating coil shown in FIG. 6 and quenched.
FIG. 11 is a perspective view of a magnetic material attached to the high-frequency induction heating coil.
[Explanation of symbols]
1a First step
1b Second step
2 Stepped shaft member
3 Large diameter shaft
4 Small diameter shaft
4a Rising part (root)
5a First corner
5b Second corner
6a First seat portion
6b Second seat surface
7a first shoulder
7b Second shoulder
30 High frequency induction heating coil
33 first step heating conductor
36 Second step heating conductor
37 1st small diameter shaft portion heating conductor
38 Second small diameter shaft portion heating conductor
40 Third small diameter shaft heating conductor
L gap part (seam part)
R₁  1st circumference
R₂  Second peripheral surface
S Quench hardened layer pattern
α The length of the arc of the first step heating conductor
β The length of the arc of the second step heating conductor
θ₁  Central angle of arc of first step heating conductor
θ₂  Central angle of arc of second step heating conductor
θ₃  Central angle of arc of second small diameter shaft heating conductor
θ₄  Central angle of arc of third small diameter shaft heating conductor

Claims

A large diameter shaft having a relatively large diameter, a small diameter shaft having a relatively small diameter, and first and second steps formed between the large diameter shaft and the small diameter shaft, respectively. And a high frequency induction heating coil for high frequency induction heating of the stepped shaft member having
(A) an arc-shaped first step heating conductor arranged corresponding to the first step provided on a shaft part having a relatively large diameter;
(B) an arc-shaped second step heating conductor connected to the first step heating conductor and arranged corresponding to the second step provided on a shaft portion having a relatively small diameter;
(C) a first small-diameter shaft portion heating conductor having a linear shape connected to the second step portion heating conductor and arranged corresponding to the small-diameter shaft portion in a state parallel to the axis of the small-diameter shaft portion; When,
(D) connected to the first small-diameter shaft portion heating conductor and a first peripheral surface portion at a position farthest from the large-diameter shaft portion among the peripheral surfaces of the small-diameter shaft portion to be heated; An arc-shaped second small-diameter shaft portion heating conductor correspondingly disposed;
(E) connected to the second small-diameter shaft portion heating conductor and provided so as to face the second small-diameter shaft portion heating conductor, and the large- diameter portion of the peripheral surface of the small-diameter shaft portion to be heated An arc-shaped third small-diameter shaft portion corresponding to a second peripheral surface portion facing the first peripheral surface portion at a position between a position farthest from the radial shaft portion and the large- diameter shaft portion. A heating conductor;
Respectively,
One winding part including the first and second step heating conductors and one winding part including the first, second and third small diameter heating conductors are configured as a whole. Is configured as a continuous two-turn winding structure,
The first small-diameter shaft portion heating conductor is disposed so as to pass through a location corresponding to a gap between the second and third small-diameter shaft portion heating conductors in the axial direction of the small-diameter shaft portion,
The relationship between the arc length α of the first step heating conductor and the arc length β of the second step heating conductor is set so that α ≧ β,
A high frequency induction heating coil.

Assuming that the condition α ≧ β is satisfied, the central angle θ ₁ of the arc of the first step heating conductor is set in the range of 60 ° ≦ θ ₁ ≦ 300 °, and the second step is high-frequency induction heating coil of claim 1, characterized in that the central angle theta ₂ arc heating conductor is set in the range of _{60 ° ≦ θ 2 ≦ 200 °} .

3. The high-frequency induction heating coil according to claim 1, wherein a magnetic material such as a dust core or a silicon steel plate is not attached to any part of the heating conductor that is a coil structure.