JP4169635B2

JP4169635B2 - Method of partial heat treatment of heat treatment member

Info

Publication number: JP4169635B2
Application number: JP2003154480A
Authority: JP
Inventors: 幸鎌田; 誠上田; 功吉田; 洋一正木; 孝雄酒井; 秋芳栗原; 郁也福田; 耕治鍋谷
Original assignee: Topy Industries Ltd
Current assignee: Topy Industries Ltd
Priority date: 2002-11-20
Filing date: 2003-05-30
Publication date: 2008-10-22
Anticipated expiration: 2023-05-30
Also published as: CN1304603C; CN1502707A; JP2004218064A

Description

【０００１】
【発明の属する技術分野】
本発明は、熱処理部材の部分熱処理方法に関する。
熱処理部材は、たとえば建設機械の無限軌道帯用リンクであり、その場合、部分熱処理される部分は、ローラー踏面部である。ただし、熱処理部材は、建設機械の無限軌道帯用リンクに限るものではない。
また、部分熱処理は、部分焼入れ、または部分焼もどし、または部分焼入れおよび部分焼もどしの何れかである。
【０００２】
【従来の技術】
鉄鋼部材は、圧延または鍛造または鋳造のままで使用されるものもあるが、耐摩耗性（硬さ）、強度、靱性が要求される部材は、熱処理が施される。このように、熱処理を施して使用される部材を「熱処理部材」という。
代表的な熱処理部材として、図１２に示す、油圧ショベルおよびブルドーザー等の建設機械の無限軌道帯に使用される履板２、リンク１、ピン３、ブッシュ４、およびブルドーザー等の建設機械および除雪機械に使用される刃先（図示せず）などがある。その他、各種産業機械に使用される機械構造用部品の多くは熱処理部材である。
無限軌道帯用リンクは、過酷な条件下で使用されるため、リンク全体として耐摩耗性、強度および靱性が要求される。また、建設機械の下部走行体のローラー（転輪、図示せず）との接触面領域である、リンク１のローラー踏面部１ａ（図１３、図１４）には、特に耐摩耗性が要求される。
【０００３】
これらの要求特性を備えるために、無限軌道帯用リンクは、以下の（ｉ）〜（ｖ）の工程により、（ｉ）〜（ｖ）の工程順で、製造されている。
（ｉ）中炭素合金鋼からなる素材を熱間鍛造してリンク形状のリンク素材とする。
（ ii ）熱間鍛造の残熱または再加熱でＡｃ₃変態点以上の温度になっている、リンク素材の全体を急冷して焼入れする。
(iii) 焼入れしたリンク素材全体を高温焼もどしする。
（ iv ）高温焼もどししたリンク素材のローラ踏面部のみを誘導加熱焼入れする（いわゆる、部分焼入れ）。
（ｖ）リンク素材のローラ踏面部のみを誘導加熱により低温焼もどしする（いわゆる部分焼もどし）か、または、リンク素材全体を炉中にて低温焼もどしする。
なお、（ iv ）、（ｖ）の工程の前後で、他の部品と組み立てるために機械加工を実施する。
【０００４】
したがって、リンク素材には、（ ii ）、(iii) の第１段階の熱処理と、（ iv ）、（ｖ）の第２段階の熱処理との、２段階の熱処理が施される。第１段階の熱処理は、リンク全体に強度および靱性を付与するための熱処理であり、第２段階の熱処理は、リンクの一部分であるローラー踏面部に耐摩耗性を付与するための熱処理である。このように、２段階の熱処理を施す理由は、リンクの部位によって要求される機械的性質が異なるためである。ここで、第１段階の熱処理のようにリンク素材全体に施される熱処理を「全体熱処理」といい、第２段階の熱処理のようにリンク素材の一部分に施される熱処理を「部分熱処理」という。
【０００５】
本発明は、上記（ｉ）〜（ｖ）のリンクの製造工程のうち、部分熱処理工程に係るものである。すなわち、本発明は、
（ｉ）（ iv ）の工程、すなわち、部分焼入れ工程と、（ｖ）の工程、すなわち、部分焼もどし工程との両方の工程、または、
（ii）（ iv ）の工程、すなわち、部分焼入れ工程、もしくは、
（iii) （ｖ）の工程、すなわち、部分焼もどし工程、
の何れかに関するものである。
【０００６】
リンク素材の部分熱処理（（ iv ）の部分焼入れ、（ｖ）の部分焼もどし）には、従来、つぎの方法がある。
〔部分焼入れ〕
イ．リンク素材全体を冷却液槽内の冷却液中に浸漬する方法
ロ．冷却槽内でリンク素材を搬送しつつ、リンク素材のローラー踏面部のみに、大気中または液中にて、噴射ジャケットより冷却液を噴射する方法（ジェット冷却、たとえば特開昭５８−１６７７２７号公報）
ハ．リンク素材のローラー踏面部のみに、大気中にて、高圧の空気により、冷却液を噴射する方法（高圧スプレー冷却）
〔部分焼もどし〕
ニ．１工程の誘導加熱方法（たとえば、特開昭５７−５１５８３号公報）
ホ．炉中加熱方法（たとえば、特開昭５７−５１５８３号公報における従来の技術の説明）
【０００７】
【特許文献１】
特開昭５８−１６７７２７号公報
【特許文献２】
特開昭５７−５１５８３号公報
【０００８】
【発明が解決しようとする課題】
しかし、従来の部分熱処理方法には、つぎの問題がある。
〔従来の部分焼入れ方法の問題点〕
イ．の方法では、リンク素材全体は常に冷却液に接触しているが、液流がないため、冷却能力が低く、また、冷却が不均一になりやすい。その結果、焼入れ硬さ不足（いわゆる、不完全焼入れ）、焼入れ硬さ不均一（いわゆる、焼むら）、焼割れ等の品質不良が発生しやすい。
ロ．の方法では、とくに液中噴射では、冷却液中をリンクが移動するので、冷却したい部位に冷却液流を噴射して効果的に冷却するのが困難である。また、リンクのような複雑な形状の部材の場合、冷却が不均一になりやすく、焼割れ等の品質不良が発生しやすい。
ハ．の方法では、高圧噴射装置、ワーククランパー、大容量液槽、大型カバーなどが必要になるため、設備が大型になり、設備製作コストおよび設備保全コストが高くなる。
〔従来の部分焼もどし方法の問題点〕
ニ．の方法では、特定部分の、表面と芯部との温度差が大きくなり、特定部分全体を均一な温度に加熱することが困難である。
ホ．の方法では、加熱時間が長くなるため、焼もどし工程がネックとなり、インラインによる一貫生産が非常に困難である。
【０００９】
本発明の目的は、従来の部分熱処理の上記問題点の１つ以上を解消できる、熱処理部材の部分熱処理方法（部分焼入れ方法、または部分焼もどし方法、または部分焼入れ方法と部分焼もどし方法の両方、の何れであってもよい）を提供することにある。
【００１０】
より具体的には、つぎの通りである。
本発明の第１の目的は、部分熱処理の加熱工程において、短時間の加熱で、特定部分を均一な温度に加熱することを可能とする、熱処理部材の部分熱処理方法を提供することにある。
本発明の第２の目的は、部分熱処理の冷却工程において、熱処理硬さ不足、熱処理硬さ不均一、および熱処理割れ等の品質不良の発生を防止し、かつ、設備関連コストの低減を可能とする、熱処理部材の部分熱処理方法を提供することにある。
本発明の第３の目的は、部分熱処理の加熱工程において、短時間の加熱で、特定部分を均一な温度に加熱することを可能とし、部分熱処理の冷却工程において、熱処理硬さ不足、熱処理硬さ不均一、および熱処理割れ等の品質不良の発生を防止し、かつ、設備関連コストの低減を可能とする、熱処理部材の部分熱処理方法を提供することにある。
【００１１】
【課題を解決するための手段】
上記目的は以下の本発明によって達成される。
（１）熱処理部材の特定部分のみを熱処理する部分熱処理方法であって、
前記部分熱処理は、部分焼入れ、および／または、部分焼もどしを含んでおり、
前記特定部分は該特定部分の表面部と該特定部分の芯部を含んでおり、
前記熱処理は、前記特定部分のみを誘導加熱する誘導加熱工程と、ついで行われる冷却工程とを含んでおり、
前記誘導加熱工程が、第１段階の加熱と、該第１段階の加熱に続く加熱休止と、該加熱休止に続く第２段階の加熱を含んでおり、
前記第１段階の加熱では、熱処理部材の特定部分を所定の温度に向けて急速加熱し、該所定の温度は、前記熱処理が部分焼入れの場合はＡｃ₃変態点以上の温度、前記熱処理が部分焼もどしの場合は２００℃〜３００℃の温度であり、前記第１段階の加熱終了時には前記特定部分の表面部と前記特定部分の芯部との間に温度差が生じ、
前記加熱休止では、前記特定部分の表面部に偏在した熱を大気に放散させるとともに芯部に伝導させて、前記表面部の温度を低下させるとともに前記芯部の温度を上昇させて、前記表面部と前記芯部との温度差を減少させ、
前記第２段階の加熱では、前記第２段階の加熱の加熱出力を前記第１段階の加熱の加熱出力と等しいかそれよりも低く設定して、前記熱処理部材の特定部分全体を均一な温度に、かつ、前記所定の温度に、加熱する、
熱処理部材の部分熱処理方法。
（２）前記熱処理部材の特定部分の加熱中、前記熱処理部材を固定する（１）記載の熱処理部材の部分熱処理方法。
（３）１つの加熱コイルが１つの熱処理部材を加熱する（１）記載の熱処理部材の部分熱処理方法。
（４）前記第１段階の加熱と前記第２段階の加熱を別個の加熱コイルを用いて行う（３）記載の熱処理部材の部分熱処理方法。
（５）前記第１段階の加熱を行う加熱コイルと前記第２段階の加熱を行う加熱コイルが互いに異なる形状を有している（４）記載の熱処理部材の部分熱処理方法。
（６）前記第１段階の加熱を行う加熱コイルと前記第２段階の加熱を行う加熱コイルは同一の形状を有している（４）記載の熱処理部材の部分熱処理方法。
（７）前記第１段階の加熱と前記第２段階の加熱を同じ加熱コイルを用いて行う（３）記載の熱処理部材の部分熱処理方法。
（８）１つの加熱コイルが熱処理部材を２つ加熱する（１）記載の熱処理部材の部分熱処理方法。
（９）前記冷却工程では、前記熱処理部材の全体を冷却液槽内の冷却液中の定位置に浸漬して静止させる（１）記載の熱処理部材の部分熱処理方法。
（１０）前記冷却工程では、噴射ジャケットより流出する冷却液流を前記特定部分に噴射する（１）記載の熱処理部材の部分熱処理方法。
（１１）前記熱処理部材が無限軌道帯用リンクである（１）記載の熱処理部材の部分熱処理方法。
（１２）前記特定部分が前記リンクのローラー踏面部である（１１）記載の熱処理部材の部分熱処理方法。
【００１２】
上記（１）の部分熱処理方法では、加熱工程において、誘導加熱が２段階の加熱で行われ、１段目の加熱と２段目の加熱との間に加熱休止時間を設けたので、１段目の加熱で特定部分の表面に偏在した熱が芯部に伝導して表面と芯部との温度差が減少し、熱処理部材の特定部分全体を均一な温度に加熱することができる。
上記（１）の部分熱処理方法では、２段目の加熱は１段目の加熱と等しいかまたはそれより低い出力での加熱のため、表面と芯部との温度差がさらに減少し、その結果、熱処理部材の特定部分全体を均一な温度に加熱することができる。
上記（２）の部分熱処理方法では、熱処理部材の特定部分の加熱中、熱処理部材を固定するので、熱処理部材が加熱コイルに対して変位せず、特定部分を所定深さで所定温度に加熱することができる。
上記（３）〜（６）の部分熱処理方法では、ワークを第１段階の加熱の加熱コイル（第１加熱コイル）で加熱し、加熱休止中にワークを第２段階の加熱の加熱コイル（第２加熱コイル）に送り、ワークを第２加熱コイルで加熱するが、ワークを第２加熱コイルで加熱中につぎのワークを第１加熱コイルで加熱することができ、生産性の向上をはかることができる。
上記（７）の部分熱処理方法では、同じ（単一の）加熱コイルで、第１段階の加熱、加熱休止、第２段階の加熱を行うので、加熱コイルの数量が削減され、その結果、加熱コイルの製作費用が削減される。
上記（８）の部分熱処理方法では、ワークを１つの加熱コイルの上流部で加熱し、加熱休止中にワークを前記１つの加熱コイルの下流部に送り、ワークを加熱コイルの下流部で加熱するが、ワークを加熱コイルの下流部で加熱中につぎのワークを加熱コイルの上流部で加熱することができ、生産性を倍増することができる。
上記（９）の部分熱処理方法では、とりわけ、冷却工程で、熱処理部材の全体を冷却液槽内の冷却液中の定位置に浸漬して静止させるので、特定部分を狙って冷却液を噴射でき、熱処理の品質を向上できる。また、ワーク搬送方向に熱処理装置がコンパクトになり、設備関連コストを低減することができる。
上記（１０）の部分熱処理方法では、とりわけ、冷却工程で、噴射ジャケットより流出する冷却液流を特定部分に噴射するので、十分な冷却能力が確保されるとともに、冷却が均一になり、熱処理の品質を向上できる。
上記（１１）、（１２）の部分熱処理方法では、本発明を無限軌道帯用リンクのローラー踏面に適用して、機械的品質の向上をはかることができる。
【００１３】
【発明の実施の形態】
以下に、本発明の熱処理部材の部分熱処理方法を、図１〜図１４（図１２〜図１４は従来技術の説明と共用）を参照して説明する。
熱処理部材１として、建設機械の無限軌道帯用リンクを例にとる。ただし、熱処理部材は建設機械の無限軌道帯用リンクに限るものではない。また、熱処理部材１が建設機械の無限軌道帯用リンク１である場合、熱処理が施される特定部分１ａはローラー踏面部である。
【００１４】
まず、本発明の熱処理部材の部分熱処理方法を説明する。
図１に示すように、本発明の熱処理部材の部分熱処理方法は、熱処理部材１の特定部分１ａのみを熱処理する部分熱処理方法である。
本発明の熱処理部材の部分熱処理方法は、熱処理部材１の特定部分１ａのみを誘導加熱する誘導加熱工程２０と、ついで行われる冷却工程３０を含む。誘導加熱では、高周波誘導電流により特定部分１ａのみを局部的に加熱する。
誘導加熱工程２０において、本発明方法による誘導加熱工程に符号２０Ｐを付し、従来方法による誘導加熱工程に符号２０Ｃを付す。
【００１５】
本発明の誘導加熱工程２０Ｐは、第１段階の加熱２１と、該第１段階の加熱に続く加熱休止２２と、該加熱休止に続く第２段階の加熱２３を有している。すなわち、第１段階の加熱２１と第２段階の加熱２３との２段階の加熱の間に加熱休止（放熱時間）２２が設けられている。加熱休止（放熱時間）２２は約５〜１５秒程度である。本発明の２段階の加熱では、第１段階の加熱２１の加熱出力が第２段階の加熱２３の加熱出力と等しいかそれよりも高く設定されている。
【００１６】
第１段階の加熱２１で熱処理部材１の特定部分１ａを急速加熱し、ほぼ所定の温度まで上昇させる。第１段階の加熱２１の加熱終了後では、加熱コイル１１に近い熱処理部材１の特定部分１ａの表面近傍部の加熱温度は加熱コイル１１と離れている特定部分１ａの芯部の温度と比較して高くなっている。すなわち、第１段階の加熱２１の加熱終了後では、熱処理部材１には比較的大きな温度差を有する温度分布（温度ムラ）があり、特定部分１ａにおいても表面部と芯部とで温度差がある。
つぎに、第１段階の加熱２１と第２段階の加熱２３との間の加熱休止（放熱時間）２２において、特定部分１ａの表面近傍部から大気への熱放散と、特定部分１ａの表面部から特定部分１ａの芯部への熱伝導とにより、特定部分１ａにおける温度ムラが減少し、特定部分１ａを均熱化することができる。
さらに、第２段階の加熱２３で、第１段階の加熱２１の加熱に比べて加熱出力を同一もしくは低くし、かつ、加熱コイル１１の形状も均熱化しやすいコイル形状とすることで、熱処理部材１の特定部分１ａをより均熱化することができる。
【００１７】
２段加熱とその間の放熱時間により、従来存在した温度ムラがほとんどなくなり、焼入れ硬さや焼もどし硬さなど、製品の品質が安定する。また、加熱時間も各段（第１段階の加熱も第２段階の加熱もそれぞれ）３０〜６０秒程度と短く、加熱休止も約５〜１５秒程度と短く、炉加熱による焼もどしのような３〜４時間といった長時間の処理は不要となる。
【００１８】
図９に示すように、熱処理部材１の特定部分１ａの加熱中、熱処理部材１をクランプ装置１２によって固定する。また、加熱中、熱処理部材１は搬送されず、静止している。クランプによって、誘導加熱コイル（単に、加熱コイルともいう）１１と熱処理部材１との位置関係が固定され、特定部分１ａの安定した加熱が行われる。
【００１９】
誘導加熱においては、１つの加熱コイル１１が１つの熱処理部材１を加熱してもよいし（図５）、加熱コイル１１を長くしておいて１つの加熱コイル１１が２つの熱処理部材１を加熱してもよい（図６）。
【００２０】
１つの加熱コイル１１が１つの熱処理部材１を加熱する場合、第１段階の加熱２１と第２段階の加熱２３を別々の加熱コイル１１を用いて行ってもよい。その場合は、加熱コイル１１は２セットとなる（図５）。
【００２１】
第１段階の加熱２１と第２段階の加熱２３を別々の加熱コイル１１を用いて行う場合、第１段階の加熱２１で用いる加熱コイル１１（図７）と第２段階の加熱２３で用いる加熱コイル１１（図８）の形状が異なってもよいし、あるいは、第１段階の加熱２１で用いる加熱コイルと第２段階の加熱２３で用いる加熱コイルの形状が同じであってもよい。また、この場合は、熱処理部材１の、第１段階の加熱２１の加熱コイル１１（図７）から第２段階の加熱２２の加熱コイル１１への搬送（移動）時間が加熱休止時間（放熱時間）２２になる。
【００２２】
１つの加熱コイル１１が１つの熱処理部材１を加熱する場合、第１段階の加熱２１と第２段階の加熱２３を同一の（単一の）加熱コイル１１を用いて行ってもよい。その場合は、加熱コイル１１は１セットとなる。
加熱コイル１１が１セットの場合、ハード面で、１段目加熱用タイマー、放冷用タイマー、２段目加熱用タイマー、および、１段目加熱出力、２段目加熱出力をそれぞれ設定し、ソフト面で、それぞれを規定時間ずつ順に動作させる。ただし、この方法は、均熱化が同一加熱コイルで得られる場合にのみ適用される。
【００２３】
１つの加熱コイル１１が２つの熱処理部材１を加熱する場合は（図６）、熱処理部材１を１つの加熱コイル１１の上流部１１ａで加熱し、加熱休止２２中に熱処理部材１を加熱コイル１１の上流部１１ａから加熱コイル１１の下流部１１ｂに送り、熱処理部材１を加熱コイル１１の下流部１１ｂで加熱する。この場合は、当然のことながら、１段目の加熱出力と２段目の加熱出力は、同一である。また、１段目の加熱時間と２段目の加熱時間も同一である。さらに、ハード面、ソフト面で、加熱休止時間において、加熱電源が切れると同時にクランプ装置１２が解除されて熱処理部材１がコイル１１の上流部１１ａからコイル１１の下流部１１ｂへ移動し始め、熱処理部材１がコイル１１の下流部１１ｂの所定位置に到達すると同時にクランプ装置１２が作動して熱処理部材１をコイル１１の下流部１１ｂの所定位置に固定するとともに、加熱電源が入って第２段階の加熱２３が開始されるようにする。こうすることにより、熱処理部材１を加熱コイル１１の下流部１１ｂで加熱中につぎの熱処理部材１を加熱コイル１１の上流部１１ａで加熱することができ、生産性を倍増することができる。すなわち、同じ時間で２倍の数の熱処理部材１を処理することができる。
【００２４】
冷却工程３０では、とりわけ部分熱処理が部分焼入れの場合（ただし、部分熱処理が部分焼もどしの場合に適用してもよい）、図１０、図１１に示すように、加熱工程２０で特定部分１ａのみが所定温度以上に誘導加熱された熱処理部材１の全体を、冷却液槽５内の冷却液６中の定位置に浸漬して静止させたまま、噴射ジャケット７の噴射穴より流出する冷却液流８を特定部分１ａに噴射し、冷却する。
【００２５】
熱処理部材１が、冷却液槽５の上方位置にある該部材１を搬送するローラーコンベヤー９の一部のローラー１０の上に搬送されて来た時に、一部のローラー１０および噴射ジャケット７ごと熱処理部材１の全体を冷却液槽５内の冷却液６中に機械的に浸漬し、なおかつ、噴射ジャケット７より大量の冷却液を３方向（左右２方向および上方）から流出させて熱処理部材１の特定部分１ａに噴射し、浸漬および液流により冷却する。冷却が完了すると、熱処理部材１を一部のローラー１０および噴射ジャケット７ごと下降前の位置に上昇させ、ついで搬出する。冷却および搬入・搬出のすべての工程は、自動制御で行われる。
焼入れに用いる冷却液としては、水、水溶性焼入れ液、油等があり、いずれの冷却液を用いてもよい。コスト面および作業環境面からは、水を使用することが望ましい。
【００２６】
浸漬および液流により冷却することで、十分な冷却速度を確保するとともに、均一な冷却を確保する。冷却速度を十分確保することで、必要な品質（焼入れ硬さ、焼もどし硬さなど）が得られ、かつ、冷却速度を均一とすることで、焼割れ防止をはかることができる。また、熱処理部材１を冷却液槽５内の冷却液６中の定位置に静止させて冷却するので、熱処理部材１が冷却中に冷却液槽を移動する冷却方法に比べて、噴射ジャケット７と熱処理部材１の干渉がなくなり、噴射ジャケット７の噴射穴と熱処理部材１との間隔を短くとることができるようになるので、噴射液流の流れが弱まらず、十分な速度の液流を噴射することができ、高い冷却速度を確保することができるので、必要な品質が得られる。また、熱処理部材１を静止させて冷却するので、熱処理部材１が冷却中に冷却液槽を移動する冷却方法に比べて、冷却液槽５の、熱処理部材１の搬送方向の長さが短縮され、設備製作費、設備ランニングコストが低減する。
【００２７】
本発明の第１段階の加熱２１、加熱休止２２、第２段階の加熱２３の加熱工程２０Ｐを有する本発明の部分熱処理は、部分焼入れに適用されてもよいし（図３）、または部分焼もどしに適用されてもよいし（図２）、または部分焼入れおよび部分焼もどしの両方に適用されてもよい（図４）。
【００２８】
図２の本発明の部分熱処理方法（本発明の部分加熱２０Ｐが焼もどしの部分加熱に適用された場合）は、部分焼入れ工程１００と部分焼もどし工程２００とを有する。
部分焼入れ工程１００は、熱処理部材１の特定部分１ａのみをＡｃ₃変態点以上の温度に誘導加熱する工程２０Ｃと、特定部分のみがＡｃ₃変態点以上の温度に誘導加熱された熱処理部材１の全体を冷却液槽５内の冷却液６中の定位置に浸漬して静止させたまま、噴射ジャケット７の噴射穴より流出する冷却液流８を特定部分１ａに噴射する冷却工程３０を有する。
部分焼もどし工程２００は、熱処理部材１の特定部分１ａのみを大気中で約２００〜３００℃の温度に誘導加熱する誘導加熱工程２０Ｐと、冷却工程（強制冷却でも自然冷却であってもよい）３０を含む。この部分焼もどし工程の誘導加熱工程２０Ｐは、第１段階の加熱２１と、第１段階の加熱２１に続く加熱休止（放熱時間）２２と、該加熱休止２２に続く第２段階の加熱２３とを有する。
【００２９】
図３の本発明の部分熱処理方法（本発明の部分加熱２０Ｐが焼入れの部分加熱に適用された場合）は、部分焼入れ工程１００と部分焼もどし工程２００とを有する。
部分焼入れ工程１００は、熱処理部材１の特定部分１ａのみをＡｃ₃変態点以上の温度に誘導加熱する工程２０Ｐと、特定部分のみがＡｃ₃変態点以上の温度に誘導加熱された熱処理部材１の全体を冷却液槽５内の冷却液６中の定位置に浸漬して静止させたまま、噴射ジャケット７の噴射穴より流出する冷却液流８を特定部分１ａに噴射する冷却工程３０を有する。この部分焼入れ工程の誘導加熱工程２０Ｐは、第１段階の加熱２１と、第１段階の加熱２１に続く加熱休止（放熱時間）２２と、該加熱休止２２に続く第２段階の加熱２３とを有する。
部分焼もどし工程２００は、熱処理部材１の特定部分１ａのみを大気中で約２００〜３００℃の温度に誘導加熱する誘導加熱工程２０Ｃと、冷却工程（強制冷却でも自然冷却であってもよい）３０を含む。
【００３０】
図４の本発明の部分熱処理方法（本発明の部分加熱２０Ｐが焼入れの部分加熱と焼もどしの部分加熱の両方に適用された場合）は、部分焼入れ工程１００と部分焼もどし工程２００とを有する。
部分焼入れ工程１００は、熱処理部材１の特定部分１ａのみをＡｃ₃変態点以上の温度に誘導加熱する工程２０Ｐと、特定部分のみがＡｃ₃変態点以上の温度に誘導加熱された熱処理部材１の全体を冷却液槽５内の冷却液６中の定位置に浸漬して静止させたまま、噴射ジャケット７の噴射穴より流出する冷却液流８を特定部分１ａに噴射する冷却工程３０を有する。この部分焼入れ工程の誘導加熱工程２０Ｐは、第１段階の加熱２１と、第１段階の加熱２１に続く加熱休止（放熱時間）２２と、該加熱休止２２に続く第２段階の加熱２３とを有する。
部分焼もどし工程２００は、熱処理部材１の特定部分１ａのみを大気中で約２００〜３００℃の温度に誘導加熱する誘導加熱工程２０Ｐと、冷却工程（強制冷却でも自然冷却であってもよい）３０を含む。この部分焼もどし工程の誘導加熱工程２０Ｐは、第１段階の加熱２１と、第１段階の加熱２１に続く加熱休止（放熱時間）２２と、該加熱休止２２に続く第２段階の加熱２３とを有する。
【００３１】
つぎに、上記の部分熱処理方法を実施する、部分熱処理装置を、図５〜図１４を参照して説明する。
この部分熱処理装置は、熱処理部材１の特定部分１ａのみを熱処理する部分熱処理装置であって、特定部分１ａのみを誘導加熱する誘導加熱装置（誘導加熱コイル１１を含む）と、特定部分１ａが加熱された熱処理部材１を冷却する冷却装置５〜１０とを含んでいる。誘導加熱装置は、第１段階の加熱２１、加熱休止２２、第２段階の加熱２３を順に行う１つ以上の加熱コイル１１を有している。
【００３２】
第１段階の加熱２１の加熱出力は第２段階の加熱２３の加熱出力と同一もしくはそれ以上に設定可能である。
部分熱処理装置は、熱処理部材１の特定部分１ａの加熱中、熱処理部材１を固定するクランプ装置１２を備えている。
１つの加熱コイル１１が１つの熱処理部材１を加熱してもよい（図５）。
１つの加熱コイル１１が１つの熱処理部材１を加熱する場合は、第１段階の加熱２１を行う加熱コイル１１と第２段階の加熱２３を行う加熱コイル１１は別々の加熱コイルであってもよいし、同じ（単一の）加熱コイル１１であってもよい。
第１段階の加熱２１を行う加熱コイル１１と第２段階の加熱２３を行う加熱コイル１１が別個の加熱コイルである場合は、第１段階の加熱２１を行う加熱コイル１１と第２段階の加熱２３を行う加熱コイル１１が互いに異なる形状を有していてもよいし、同一の形状を有していてもよい。
１つの加熱コイル１１が熱処理部材１を２つ加熱するものであってもよい（図６）。
【００３３】
冷却装置は、搬送される熱処理部材１を冷却液槽５内の冷却液６中の定位置に浸漬して静止させるローラーコンベヤー１０を備えている。
冷却装置は、流出する冷却液流８を熱処理部材１の特定部分１ａに噴射する噴射ジャケット７を備えている。
熱処理部材１は、たとえば、無限軌道帯用リンクである。熱処理部材１が無限軌道帯用リンクである場合、特定部分１ａはリンクのローラー踏面部である。
部分熱処理は、部分焼入れであってもよいし、部分焼もどしであってもよいし、部分焼入れと部分焼もどしの両方であってもよい。
【００３４】
【発明の効果】
請求項１の部分熱処理方法によれば、加熱工程において、誘導加熱が２段階の加熱で行われ、１段目の加熱と２段目の加熱との間に加熱休止時間を設けたので、熱処理部材の特定部分全体を均一な温度に加熱することができる。
請求項１の部分熱処理方法によれば、２段目の加熱は１段目の加熱と同一またはそれより低い出力での加熱のため、熱処理部材の特定部分全体を均一な温度に加熱することができる。
請求項２の部分熱処理方法によれば、加熱中、熱処理部材を固定するので、特定部分を所定深さで所定温度に加熱でき、熱処理部材の品質が向上する。
請求項３〜６の部分熱処理方法によれば、生産性を高めることができる。
請求項７の部分熱処理方法によれば、加熱コイルの数量が削減され、その結果、加熱コイルの製作費用が削減される。
請求項８の部分熱処理方法によれば、生産性を倍増することができる。
請求項９の部分熱処理方法によれば、冷却工程で、熱処理部材の全体を冷却液槽内の冷却液中の定位置に浸漬して静止させるので、特定部分を狙って噴射でき、熱処理の品質の向上をはかることができる。また、ワーク搬送方向に熱処理装置がコンパクトになり、設備関連コストを低減することができる。
請求項１０の部分熱処理方法によれば、とりわけ、焼入れ冷却工程で、噴射ジャケットより流出する冷却液流を特定部分に噴射するので、十分な冷却能力が確保されるとともに、冷却が均一になる。
請求項１１、１２の部分熱処理方法によれば、本発明を無限軌道帯用リンクのローラー踏面に適用することにより、機械的品質の向上をはかることができる。
【図面の簡単な説明】
【図１】本発明の熱処理部材の部分熱処理方法の工程図である。
【図２】本発明の熱処理部材の部分熱処理方法を、部分焼もどしに適用した場合の工程図である。
【図３】本発明の熱処理部材の部分熱処理方法を、部分焼入れに適用した場合の工程図である。
【図４】本発明の熱処理部材の部分熱処理方法を、部分焼入れと部分焼もどしの両方に適用した場合の工程図である。
【図５】本発明の熱処理部材の部分熱処理方法において、１つの加熱コイルで１つの熱処理部材を加熱する場合の加熱コイルの配置図（側面図）である。
【図６】本発明の熱処理部材の部分熱処理方法において、長めの１つの加熱コイルで２つの熱処理部材を加熱する場合の加熱コイルの配置図（側面図）である。
【図７】本発明の熱処理部材の部分熱処理方法において、焼もどしに係る部分の、第１段階の加熱の加熱コイルの断面図である。
【図８】本発明の熱処理部材の部分熱処理方法において、焼もどしに係る部分の、第２段階の加熱の加熱コイルの断面図である。
【図９】本発明の熱処理部材の部分熱処理方法において、クランプ装置と加熱コイルの平面図（上から見た図）である。
【図１０】本発明の熱処理部材の部分熱処理方法の、冷却（図は焼入れの冷却の場合を示す）に係る部分の断面図である。
【図１１】図１０の部分の横断面図である。
【図１２】建設機械の無限軌道帯の一部の斜視図である。
【図１３】図１２のうちリンクの正面図である。
【図１４】図１２のうちリンクの側面図である。
【符号の説明】
１熱処理部材（たとえば、建設機械の無限軌道帯用リンク）
１ａ特定部分（たとえば、建設機械の無限軌道帯用リンクのローラー踏面部）
５冷却液槽
６冷却液
７噴射ジャケット
８冷却液流
９ローラーコンベヤー
１０一部のローラー
１１加熱コイル
１２クランプ装置
２０誘導加熱工程
２０Ｐ第１段階の加熱、加熱休止、第２段階の加熱を有する本発明の誘導加熱工程
２０Ｃ一般の加熱工程
２１第１段階の加熱
２２加熱休止
２３第２段階の加熱
３０冷却工程
１００部分焼入れ工程
２００部分焼もどし工程[0001]
BACKGROUND OF THE INVENTION
The present invention relates to partial heat treatment how heat treatment member.
The heat treatment member is, for example, a link for an endless track of a construction machine. In this case, the part to be partially heat treated is a roller tread portion. However, the heat treatment member is not limited to the endless track link of the construction machine.
The partial heat treatment is either partial quenching, partial tempering, or partial quenching and partial tempering.
[0002]
[Prior art]
Some steel members are used while being rolled, forged, or cast, but members that require wear resistance (hardness), strength, and toughness are subjected to heat treatment. Thus, a member that is used after being subjected to heat treatment is referred to as a “heat treatment member”.
As typical heat treatment members, as shown in FIG. 12, construction machines such as a foot plate 2, a link 1, a pin 3, a bush 4, and a bulldozer used for an endless track of a construction machine such as a hydraulic excavator and a bulldozer, and a snow removal machine There are cutting edges (not shown) used for the above. In addition, many machine structural parts used in various industrial machines are heat treated members.
Since the link for the endless track is used under severe conditions, the entire link is required to have wear resistance, strength and toughness. The roller tread portion 1a (FIGS. 13 and 14) of the link 1, which is a contact surface area with the roller (roller, not shown) of the lower traveling body of the construction machine, is particularly required to have wear resistance. The
[0003]
In order to provide these required characteristics, endless track link, the following of (i) ~ (v) process, in order of steps (i) ~ (v), have been prepared.
(I) A material made of medium carbon alloy steel is hot forged to obtain a link-shaped link material.
(Ii) at Zan'netsu or reheating hot forging have become Ac ₃ transformation point or above the temperature, quenching by quenching the entire link material.
(iii) High-temperature tempering of the entire quenched link material.
( Iv ) Only the roller tread of the link material that has been tempered at high temperature is induction-heated and quenched (so-called partial quenching).
(V) Only the roller tread portion of the link material is tempered by induction heating (so-called partial tempering), or the entire link material is tempered in a furnace.
In addition, before and after the processes ( iv ) and (v) , machining is performed to assemble with other parts.
[0004]
Therefore, the link material is subjected to a two-stage heat treatment, that is, a first-stage heat treatment of ( ii ) and (iii) and a second-stage heat treatment of ( iv ) and (v) . The first-stage heat treatment is a heat treatment for imparting strength and toughness to the entire link, and the second-stage heat treatment is a heat treatment for imparting wear resistance to the roller tread portion that is a part of the link. As described above, the reason why the two-stage heat treatment is performed is that the required mechanical properties differ depending on the portion of the link. Here, the heat treatment applied to the entire link material as in the first stage heat treatment is referred to as “total heat treatment”, and the heat treatment applied to a part of the link material as in the second stage heat treatment is referred to as “partial heat treatment”. .
[0005]
The present invention relates to a partial heat treatment step among the link manufacturing steps (i) to (v) . That is, the present invention
(I) the step of ( iv ) , ie, the partial quenching step, and the step of (v) , ie, the step of partial tempering, or
(Ii) The process of ( iv ) , that is, a partial quenching process, or
(Iii) Step (v) , that is, partial tempering step,
It is related to either.
[0006]
Conventionally, there are the following methods for partial heat treatment of the link material (partial quenching in ( iv ) , partial tempering in (v)) .
[Partial quenching]
I. Method of immersing the entire link material in the coolant in the coolant tank b. A method of jetting a cooling liquid from an injection jacket in the air or in liquid only to the roller tread portion of the link material while conveying the link material in the cooling tank (jet cooling, for example, Japanese Patent Laid-Open No. 58-167727 )
C. A method of injecting coolant with high-pressure air in the atmosphere only on the roller tread of the link material (high-pressure spray cooling)
[Partial tempering]
D. One-step induction heating method (for example, JP-A-57-51583)
E. In-furnace heating method (for example, description of the prior art in JP-A-57-51583)
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 58-167727 [Patent Document 2]
JP-A-57-51583
[Problems to be solved by the invention]
However, the conventional partial heat treatment method has the following problems.
[Problems of conventional partial quenching methods]
I. In this method, the entire link material is always in contact with the cooling liquid, but since there is no liquid flow, the cooling capacity is low and the cooling tends to be uneven. As a result, poor quality such as insufficient quenching hardness (so-called incomplete quenching), non-uniform quenching hardness (so-called non-uniformity), and cracking is likely to occur.
B. In this method, in particular, in the submerged jet, the link moves in the coolant, so that it is difficult to effectively cool the part to be cooled by jetting the coolant flow. In addition, in the case of a member having a complicated shape such as a link, cooling is likely to be non-uniform and quality defects such as burning cracks are likely to occur.
C. In this method, a high-pressure injection device, a work clamper, a large-capacity liquid tank, a large cover, and the like are required, so that the equipment becomes large and the equipment manufacturing cost and equipment maintenance cost increase.
[Problems of conventional partial tempering methods]
D. In this method, the temperature difference between the surface and the core of the specific part becomes large, and it is difficult to heat the entire specific part to a uniform temperature.
E. In this method, since the heating time becomes long, the tempering process becomes a bottleneck, and in-line integrated production is very difficult.
[0009]
The object of the present invention is to achieve a partial heat treatment method (partial quenching method, partial tempering method, or both partial quenching method and partial tempering method) of a heat treated member, which can solve one or more of the above-mentioned problems of conventional partial heat treatment. Or any one of them ) .
[0010]
More specifically, it is as follows.
A first object of the present invention, in the heating step portions heat treatment in a short time of heating makes it possible to heat specific parts to a uniform temperature to provide a partial heat treatment how heat treatment member .
The second object of the present invention is to prevent the occurrence of quality defects such as heat treatment hardness deficiency, heat treatment hardness non-uniformity, heat treatment cracking and the like in the cooling process of partial heat treatment, and to reduce equipment-related costs. to to provide a partial heat treatment how heat treatment member.
The third object of the present invention is to enable heating of a specific part to a uniform temperature with a short heating time in the heating step of the partial heat treatment. In the cooling step of the partial heat treatment, the heat treatment hardness is insufficient. prevent non-uniformly, and the occurrence of quality defects of heat treatment cracks, etc., and to allow a reduction in equipment related costs, it is to provide a partial heat treatment how heat treatment member.
[0011]
[Means for Solving the Problems]
The above object is achieved by the present invention described below.
(1) A partial heat treatment method for heat treating only a specific part of a heat treatment member,
The partial heat treatment includes partial quenching and / or partial tempering,
The specific portion includes a surface portion of the specific portion and a core portion of the specific portion;
The heat treatment includes an induction heating step of induction heating only the specific portion, and a cooling step performed next,
The induction heating step includes a first stage heating, a heating pause following the first stage heating, and a second stage heating following the heating pause;
In the first stage heating, a specific portion of the heat treatment member is rapidly heated to a predetermined temperature, and the predetermined temperature is a temperature equal to or higher than the Ac ₃ transformation point when the heat treatment is partial quenching, and the heat treatment is partially performed. In the case of tempering, the temperature is 200 ° C. to 300 ° C., and at the end of the heating in the first stage, a temperature difference occurs between the surface portion of the specific portion and the core portion of the specific portion,
In the heating pause, heat that is unevenly distributed on the surface portion of the specific portion is dissipated to the atmosphere and conducted to the core portion, thereby lowering the temperature of the surface portion and increasing the temperature of the core portion, And the temperature difference between the core part and
In the second stage heating, the heating output of the second stage heating is set equal to or lower than the heating output of the first stage heating, and the entire specific portion of the heat treatment member is kept at a uniform temperature. And heating to the predetermined temperature,
A partial heat treatment method for a heat treatment member.
(2) The partial heat treatment method for a heat treatment member according to (1), wherein the heat treatment member is fixed during heating of a specific portion of the heat treatment member.
(3) The partial heat treatment method for a heat treatment member according to (1), wherein one heating coil heats one heat treatment member.
(4) The partial heat treatment method for a heat treatment member according to (3), wherein the first stage heating and the second stage heating are performed using separate heating coils.
(5) The partial heat treatment method for a heat treatment member according to (4), wherein the heating coil for performing the first stage heating and the heating coil for performing the second stage heating have different shapes.
(6) The method of partial heat treatment of a heat treatment member according to (4), wherein the heating coil for performing the first stage heating and the heating coil for performing the second stage heating have the same shape.
(7) The partial heat treatment method for a heat treatment member according to (3), wherein the first stage heating and the second stage heating are performed using the same heating coil.
(8) The partial heat treatment method for a heat treatment member according to (1), wherein one heating coil heats two heat treatment members.
(9) The partial heat treatment method for a heat treatment member according to (1), wherein, in the cooling step, the entire heat treatment member is immersed in a fixed position in a cooling liquid in a cooling liquid tank to be stationary.
(10) The partial heat treatment method for a heat treatment member according to (1), wherein, in the cooling step, a coolant flow flowing out from the injection jacket is injected to the specific portion.
(11) The partial heat treatment method for a heat treatment member according to (1), wherein the heat treatment member is an endless track link.
(12) The partial heat treatment method for a heat treatment member according to (11), wherein the specific portion is a roller tread portion of the link.
[0012]
The partial heat treatment how the above (1), in the heating process, induction heating is performed in two steps of heating, since there is provided a heating pause time between the first-stage heating and the heating of the second stage, The heat unevenly distributed on the surface of the specific portion by the first stage heating is conducted to the core portion, the temperature difference between the surface and the core portion is reduced, and the entire specific portion of the heat treatment member can be heated to a uniform temperature.
The partial heat treatment how the above (1), the second stage heating for heating in either or lower output equal to the heating of the first stage, and the temperature difference is further reduced between the surface and the core, As a result, the entire specific portion of the heat treatment member can be heated to a uniform temperature.
The partial heat treatment how the above (2), during the heating of the particular part of the heat treatment member, since to secure the heat treatment member, not displaced heat treatment member relative to the heating coil, to a predetermined temperature specific portion at a predetermined depth Can be heated.
(3) In the partial heat treatment how to (6), heating the workpiece in the heating coil of the heating of the first stage (first heating coil), heating coil heats the workpiece in the second stage during the heating pause (The second heating coil) and the workpiece is heated by the second heating coil. While the workpiece is heated by the second heating coil, the next workpiece can be heated by the first heating coil, thereby improving productivity. Can measure.
The partial heat treatment how the above (7), the same (single) heating coil, the first stage of heating, the heating pauses, since the heating of the second stage, the quantity of the heating coil is reduced, as a result The manufacturing cost of the heating coil is reduced.
The partial heat treatment how the (8), heating the workpiece at the upstream portion of one heating coil, feeding the work to the downstream portion of said one heating coil in heating pauses, downstream of the heating coils work Although heating is performed, the next workpiece can be heated at the upstream portion of the heating coil while the workpiece is being heated at the downstream portion of the heating coil, and the productivity can be doubled.
The partial heat treatment how the (9), especially, in the cooling step, since the stationary by immersing the entire heat treatment member in position in the cooling liquid of the cooling liquid in the tank, a coolant aimed at specific portion Can be sprayed to improve the quality of heat treatment. In addition, the heat treatment apparatus becomes compact in the workpiece transfer direction, and equipment-related costs can be reduced.
The partial heat treatment how the (10), especially, in the cooling step, since injecting a coolant flow flowing out from the ejection jacket to a particular part, with sufficient cooling capacity is ensured, the cooling is uniform, The quality of heat treatment can be improved.
(11), the partial heat treatment how the (12), by applying the present invention to roller path link for an endless track, it is possible to improve the mechanical quality.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the partial heat treatment how heat treatment member of the present invention, FIGS. 1 to 14 (12 to 14 of the prior art described shared) will be described with reference to.
As the heat treatment member 1, a link for an endless track of a construction machine is taken as an example. However, the heat treatment member is not limited to the link for the endless track of the construction machine. Moreover, when the heat processing member 1 is the link 1 for endless track belts of a construction machine, the specific part 1a to which heat processing is performed is a roller tread part.
[0014]
First, the partial heat processing method of the heat processing member of this invention is demonstrated.
As shown in FIG. 1, the partial heat treatment method of the heat treatment member of the present invention is a partial heat treatment method in which only a specific portion 1a of the heat treatment member 1 is heat treated.
The partial heat treatment method of the heat treatment member of the present invention includes an induction heating step 20 in which only the specific portion 1a of the heat treatment member 1 is induction-heated, and then a cooling step 30 to be performed. In the induction heating, only the specific portion 1a is locally heated by a high frequency induction current.
In the induction heating step 20, reference numeral 20P is assigned to the induction heating step according to the method of the present invention, and reference numeral 20C is assigned to the induction heating step according to the conventional method.
[0015]
The induction heating process 20P of the present invention includes a first stage heating 21, a heating pause 22 following the first stage heating, and a second stage heating 23 following the heating pause. In other words, a heating pause (heat radiation time) 22 is provided between the two-stage heating of the first-stage heating 21 and the second-stage heating 23. The heating pause (heat radiation time) 22 is about 5 to 15 seconds. In the two-stage heating of the present invention, the heating output of the first-stage heating 21 is set equal to or higher than the heating output of the second-stage heating 23.
[0016]
The specific portion 1a of the heat treatment member 1 is rapidly heated by the heating 21 in the first stage, and is raised to a substantially predetermined temperature. After the heating of the first stage heating 21 is finished, the heating temperature in the vicinity of the surface of the specific portion 1a of the heat treatment member 1 close to the heating coil 11 is compared with the temperature of the core portion of the specific portion 1a that is separated from the heating coil 11. It is high. That is, after the heating of the first stage heating 21 is finished, the heat treatment member 1 has a temperature distribution (temperature unevenness) having a relatively large temperature difference, and even in the specific portion 1a, there is a temperature difference between the surface portion and the core portion. is there.
Next, in the heating pause (heat radiation time) 22 between the first stage heating 21 and the second stage heating 23, heat dissipation from the vicinity of the surface of the specific portion 1a to the atmosphere and the surface portion of the specific portion 1a Due to the heat conduction from the core to the specific portion 1a, the temperature unevenness in the specific portion 1a is reduced and the specific portion 1a can be soaked.
Further, the heat treatment member is formed by making the heating output the same or lower in the second stage heating 23 than in the first stage heating 21 and also making the shape of the heating coil 11 easy to equalize the temperature. One specific portion 1a can be further soaked.
[0017]
Due to the two-stage heating and the heat dissipation time between them, the existing temperature unevenness is almost eliminated, and the product quality such as quenching hardness and tempering hardness is stabilized. In addition, the heating time is short for each stage (both the first stage heating and the second stage heating) are about 30 to 60 seconds, and the heating pause is also about 5 to 15 seconds, which is tempering by furnace heating. Long processing such as 3 to 4 hours is unnecessary.
[0018]
As shown in FIG. 9, the heat treatment member 1 is fixed by the clamp device 12 during heating of the specific portion 1 a of the heat treatment member 1. Further, during heating, the heat treatment member 1 is not transported and is stationary. By the clamp, the positional relationship between the induction heating coil (also simply referred to as a heating coil) 11 and the heat treatment member 1 is fixed, and the specific portion 1a is stably heated.
[0019]
In the induction heating, one heating coil 11 may heat one heat treatment member 1 (FIG. 5), or one heating coil 11 heats two heat treatment members 1 with the heating coil 11 lengthened. You may do (FIG. 6).
[0020]
When one heating coil 11 heats one heat treatment member 1, the first stage heating 21 and the second stage heating 23 may be performed using separate heating coils 11. In that case, the heating coil 11 becomes two sets (FIG. 5).
[0021]
When the first stage heating 21 and the second stage heating 23 are performed using separate heating coils 11, the heating coil 11 used in the first stage heating 21 (FIG. 7) and the heating used in the second stage heating 23. The shape of the coil 11 (FIG. 8) may be different, or the shape of the heating coil used in the first stage heating 21 and the shape of the heating coil used in the second stage heating 23 may be the same. Further, in this case, the conveyance (movement) time of the heat treatment member 1 from the heating coil 11 (FIG. 7) of the first stage heating 21 to the heating coil 11 of the second stage heating 22 is the heating pause time (heat radiation time). ) 22.
[0022]
When one heating coil 11 heats one heat treatment member 1, the first stage heating 21 and the second stage heating 23 may be performed using the same (single) heating coil 11. In that case, the heating coil 11 becomes one set.
When the heating coil 11 is one set, on the hardware side, set the first stage heating timer, the cooling timer, the second stage heating timer, the first stage heating output, and the second stage heating output, In terms of software, each is operated in sequence for a specified time. However, this method is applied only when soaking is obtained with the same heating coil.
[0023]
When one heating coil 11 heats two heat treatment members 1 (FIG. 6), the heat treatment member 1 is heated at the upstream portion 11a of one heating coil 11 and the heat treatment member 1 is heated during the heating pause 22. The heat treatment member 1 is heated by the downstream portion 11b of the heating coil 11 from the upstream portion 11a to the downstream portion 11b of the heating coil 11. In this case, as a matter of course, the heating output of the first stage and the heating output of the second stage are the same. The first stage heating time and the second stage heating time are also the same. Furthermore, on the hard surface and the soft surface, during the heating pause time, the clamping device 12 is released at the same time as the heating power is turned off, and the heat treatment member 1 starts to move from the upstream portion 11a of the coil 11 to the downstream portion 11b of the coil 11, and heat treatment is performed. At the same time that the member 1 reaches a predetermined position in the downstream portion 11b of the coil 11, the clamping device 12 operates to fix the heat treatment member 1 in a predetermined position in the downstream portion 11b of the coil 11, and the heating power is turned on to enter the second stage. Heating 23 is started. By carrying out like this, the next heat processing member 1 can be heated by the upstream part 11a of the heating coil 11, while heating the heat processing member 1 by the downstream part 11b of the heating coil 11, and productivity can be doubled. That is, twice as many heat treatment members 1 can be processed in the same time.
[0024]
In the cooling step 30, in particular, when the partial heat treatment is partial quenching (however, it may be applied when the partial heat treatment is partial tempering), as shown in FIGS. 10 and 11, only the specific portion 1 a in the heating step 20. The coolant flow that flows out from the spray hole of the spray jacket 7 while the heat treatment member 1 that has been induction-heated above the predetermined temperature is immersed in a fixed position in the coolant 6 in the coolant tank 5 and is kept stationary. 8 is injected to the specific part 1a and cooled.
[0025]
When the heat treatment member 1 is conveyed onto a part of the rollers 10 of the roller conveyor 9 that conveys the member 1 above the coolant tank 5, the heat treatment is performed together with some of the rollers 10 and the spray jacket 7. The entire member 1 is mechanically immersed in the cooling liquid 6 in the cooling liquid tank 5, and a large amount of the cooling liquid flows out from the jet jacket 7 from three directions (two directions in the left and right directions and above). It sprays on the specific part 1a, and it cools by immersion and a liquid flow. When the cooling is completed, the heat treatment member 1 is raised to the position before the lowering together with some of the rollers 10 and the jet jacket 7 and then carried out. All processes of cooling and loading / unloading are performed by automatic control.
Cooling liquid used for quenching includes water, water-soluble quenching liquid, oil, and the like, and any cooling liquid may be used. It is desirable to use water from the viewpoint of cost and work environment.
[0026]
Cooling by immersion and liquid flow ensures a sufficient cooling rate and uniform cooling. By ensuring a sufficient cooling rate, necessary quality (quenching hardness, tempering hardness, etc.) can be obtained, and by making the cooling rate uniform, it is possible to prevent burning cracks. In addition, since the heat treatment member 1 is cooled by being stopped at a fixed position in the coolant 6 in the coolant tank 5, compared with the cooling method in which the heat treatment member 1 moves the coolant tank during cooling, the injection jacket 7 and Interference of the heat treatment member 1 is eliminated, and the interval between the injection hole of the injection jacket 7 and the heat treatment member 1 can be shortened. Since it can inject and a high cooling rate can be ensured, the required quality is obtained. Further, since the heat treatment member 1 is cooled by being stationary, the length of the cooling liquid tank 5 in the transport direction of the heat treatment member 1 is shortened as compared with the cooling method in which the heat treatment member 1 moves the cooling liquid tank during cooling. Equipment manufacturing costs and equipment running costs are reduced.
[0027]
The partial heat treatment of the present invention having the heating step 20P of the first stage heating 21, the heating pause 22, and the second stage heating 23 of the present invention may be applied to partial quenching (FIG. 3) or partial quenching. It may be applied to tempering (FIG. 2), or it may be applied to both partial quenching and partial tempering (FIG. 4).
[0028]
The partial heat treatment method of the present invention shown in FIG. 2 (when the partial heating 20P of the present invention is applied to partial tempering) has a partial quenching step 100 and a partial tempering step 200.
Partial quenching process 100 includes the steps 20C inducing heat only specific portions 1a of the heat treatment member 1 to Ac ₃ transformation point or above the temperature, the specific portion only Ac ₃ derived heated above transformation temperatures were heat treatment member 1 There is a cooling step 30 for injecting the coolant flow 8 that flows out from the injection hole of the injection jacket 7 to the specific portion 1 a while the whole is immersed in a fixed position in the coolant 6 in the coolant tank 5 and kept stationary.
The partial tempering step 200 includes an induction heating step 20P for induction heating only the specific portion 1a of the heat treatment member 1 to a temperature of about 200 to 300 ° C. in the atmosphere, and a cooling step (may be forced cooling or natural cooling). 30 is included. The induction heating process 20P of the partial tempering process includes a first stage heating 21, a heating pause (heat radiation time) 22 following the first stage heating 21, and a second stage heating 23 following the heating pause 22. Have
[0029]
The partial heat treatment method of the present invention shown in FIG. 3 (when the partial heating 20P of the present invention is applied to partial heating for quenching) includes a partial quenching step 100 and a partial tempering step 200.
Partial quenching process 100 includes the steps 20P inducing heat only specific portions 1a of the heat treatment member 1 to Ac ₃ transformation point or above the temperature, the specific portion only Ac ₃ derived heated above transformation temperatures were heat treatment member 1 There is a cooling step 30 for injecting the coolant flow 8 that flows out from the injection hole of the injection jacket 7 to the specific portion 1 a while the whole is immersed in a fixed position in the coolant 6 in the coolant tank 5 and kept stationary. The induction heating process 20P of the partial quenching process includes a first stage heating 21, a heating pause (heat radiation time) 22 following the first stage heating 21, and a second stage heating 23 following the heating pause 22. Have.
The partial tempering step 200 includes an induction heating step 20C for induction heating only the specific portion 1a of the heat treatment member 1 to a temperature of about 200 to 300 ° C. in the atmosphere, and a cooling step (forced cooling or natural cooling may be used). 30 is included.
[0030]
The partial heat treatment method of the present invention shown in FIG. 4 (when the partial heating 20P of the present invention is applied to both partial heating and partial tempering for quenching) includes a partial quenching step 100 and a partial tempering step 200. .
Partial quenching process 100 includes the steps 20P inducing heat only specific portions 1a of the heat treatment member 1 to Ac ₃ transformation point or above the temperature, the specific portion only Ac ₃ derived heated above transformation temperatures were heat treatment member 1 There is a cooling step 30 for injecting the coolant flow 8 that flows out from the injection hole of the injection jacket 7 to the specific portion 1 a while the whole is immersed in a fixed position in the coolant 6 in the coolant tank 5 and kept stationary. The induction heating process 20P of the partial quenching process includes a first stage heating 21, a heating pause (heat radiation time) 22 following the first stage heating 21, and a second stage heating 23 following the heating pause 22. Have.
The partial tempering step 200 includes an induction heating step 20P for induction heating only the specific portion 1a of the heat treatment member 1 to a temperature of about 200 to 300 ° C. in the atmosphere, and a cooling step (may be forced cooling or natural cooling). 30 is included. The induction heating process 20P of the partial tempering process includes a first stage heating 21, a heating pause (heat radiation time) 22 following the first stage heating 21, and a second stage heating 23 following the heating pause 22. Have
[0031]
Next, perform the above partial heat treatment method, a part component heat treatment apparatus will be described with reference to FIGS. 5 to 14.
This partial heat treatment apparatus is a partial heat treatment apparatus that heats only a specific portion 1a of the heat treatment member 1, and includes an induction heating device (including the induction heating coil 11) that heats only the specific portion 1a, and the specific portion 1a is heated. Cooling devices 5 to 10 for cooling the heat treatment member 1 formed. The induction heating apparatus includes one or more heating coils 11 that sequentially perform a first stage heating 21, a heating pause 22, and a second stage heating 23.
[0032]
The heating output of the first stage heating 21 can be set equal to or higher than the heating output of the second stage heating 23.
The partial heat treatment apparatus includes a clamp device 12 that fixes the heat treatment member 1 during heating of the specific portion 1 a of the heat treatment member 1.
One heating coil 11 may heat one heat treatment member 1 (FIG. 5).
When one heating coil 11 heats one heat treatment member 1, the heating coil 11 that performs the first stage heating 21 and the heating coil 11 that performs the second stage heating 23 may be separate heating coils. The same (single) heating coil 11 may be used.
When the heating coil 11 that performs the first stage heating 21 and the heating coil 11 that performs the second stage heating 23 are separate heating coils, the heating coil 11 that performs the first stage heating 21 and the second stage heating. The heating coils 11 for performing 23 may have different shapes or the same shape.
One heating coil 11 may heat two heat treatment members 1 (FIG. 6).
[0033]
The cooling device includes a roller conveyor 10 that dries and stops the conveyed heat treatment member 1 in a fixed position in the coolant 6 in the coolant tank 5.
The cooling device includes an injection jacket 7 that injects an outflowing coolant flow 8 onto a specific portion 1 a of the heat treatment member 1.
The heat treatment member 1 is, for example, an endless track link. When the heat treatment member 1 is an endless track link, the specific portion 1a is a roller tread portion of the link.
The partial heat treatment may be partial quenching, partial tempering, or both partial quenching and partial tempering.
[0034]
【The invention's effect】
According to claim 1 of the partial heat treatment how, in the heating process, induction heating is performed in two steps of heating, since there is provided a heating pause time between the first-stage heating and the heating of the second stage, The entire specific part of the heat treatment member can be heated to a uniform temperature.
According to the partial heat treatment how according to claim 1, the heating of the second stage for heating in the first stage of heating is the same as or lower than the output, heating the entire specified portion of the heat-treated member to uniform temperature Can do.
According to the partial heat treatment how according to claim 2, during heating, so to secure the heat treatment member can be heated to a predetermined temperature specific portion at a predetermined depth, thereby improving the quality of heat treatment member.
According to the partial heat treatment how claims 3-6, productivity can be enhanced.
According to the partial heat treatment how according to claim 7, the quantity of the heating coil is reduced. As a result, manufacturing cost of the heating coil is reduced.
According to the partial heat treatment how claims 8, it is possible to double the productivity.
According to the partial heat treatment how of claim 9, in the cooling step, since the stationary by immersing the entire heat treatment member in position in the cooling liquid of the cooling liquid in the tank, can be injection aimed at particular parts, the heat treatment The quality can be improved. In addition, the heat treatment apparatus becomes compact in the workpiece transfer direction, and equipment-related costs can be reduced.
According to the partial heat treatment how claims 10, especially, in the quenching cooling step, since injecting a coolant flow flowing out from the ejection jacket to a particular part, with sufficient cooling capacity is ensured, the cooling is uniform .
According to the partial heat treatment how claims 11 and 12, by applying the present invention to roller path of the endless track link, it is possible to enhance the mechanical quality.
[Brief description of the drawings]
FIG. 1 is a process diagram of a partial heat treatment method for a heat treatment member of the present invention.
FIG. 2 is a process diagram when the partial heat treatment method for a heat treatment member of the present invention is applied to partial tempering.
FIG. 3 is a process diagram in the case where the partial heat treatment method for a heat treatment member of the present invention is applied to partial quenching.
FIG. 4 is a process diagram when the partial heat treatment method for a heat treatment member of the present invention is applied to both partial quenching and partial tempering.
[5] Oite in partial heat treatment how heat treatment member of the present invention is a layout view of a heating coil in the case of heating the single heat treatment member in one heating coil (side view).
[6] Oite in partial heat treatment how heat treatment member of the present invention is a layout view of a heating coil in the case of heating the two heat treatment member longer one heating coil (side view).
[7] Oite in partial heat treatment how heat treatment member of the present invention, the portion of the tempering, is a cross-sectional view of the heating coil of the heating of the first stage.
[8] Oite in partial heat treatment how heat treatment member of the present invention, the portion of the tempering, is a cross-sectional view of the heating coil of the heating of the second stage.
[9] Oite in partial heat treatment how heat treatment member of the present invention, is a plan view of the clamping device and the heating coil (top view).
[10] parts heat treatment how heat treatment member of the present invention, the cooling (the figure shows the case of quenching cooling) is a cross-sectional view of a portion of the.
11 is a cross-sectional view of the portion of FIG.
FIG. 12 is a perspective view of a part of the endless track of the construction machine.
FIG. 13 is a front view of a link in FIG.
14 is a side view of a link in FIG.
[Explanation of symbols]
1 Heat treatment member (for example, link for endless track of construction machinery)
1a Specific part (for example, roller tread part of link for endless track belt of construction machine)
DESCRIPTION OF SYMBOLS 5 Coolant tank 6 Coolant 7 Injection jacket 8 Coolant stream 9 Roller conveyor 10 Some rollers 11 Heating coil 12 Clamping device 20 Induction heating process 20P The book which has 1st stage heating, heating pause, and 2nd stage heating Induction heating process 20C of the invention General heating process 21 First stage heating 22 Heating pause 23 Second stage heating 30 Cooling process 100 Partial quenching process 200 Partial tempering process

Claims

A partial heat treatment method for heat treating only a specific part of a heat treatment member,
The partial heat treatment includes partial quenching and / or partial tempering,
The specific portion includes a surface portion of the specific portion and a core portion of the specific portion;
The heat treatment includes an induction heating step of induction heating only the specific portion, and a cooling step performed next,
The induction heating step includes a first stage heating, a heating pause following the first stage heating, and a second stage heating following the heating pause;
In the first stage heating, a specific portion of the heat treatment member is rapidly heated to a predetermined temperature, and the predetermined temperature is a temperature equal to or higher than the Ac ₃ transformation point when the heat treatment is partial quenching, and the heat treatment is partially performed. In the case of tempering, the temperature is 200 ° C. to 300 ° C., and at the end of the heating in the first stage, a temperature difference occurs between the surface portion of the specific portion and the core portion of the specific portion,
In the heating pause, heat that is unevenly distributed on the surface portion of the specific portion is dissipated to the atmosphere and conducted to the core portion, thereby lowering the temperature of the surface portion and increasing the temperature of the core portion, And the temperature difference between the core part and
In the second stage heating, the heating output of the second stage heating is set equal to or lower than the heating output of the first stage heating, and the entire specific portion of the heat treatment member is kept at a uniform temperature. And heating to the predetermined temperature,
A partial heat treatment method for a heat treatment member.

The partial heat treatment method for a heat treatment member according to claim 1, wherein the heat treatment member is fixed during heating of a specific portion of the heat treatment member.

The partial heat treatment method of a heat treatment member according to claim 1, wherein one heating coil heats one heat treatment member.

The partial heat treatment method for a heat treatment member according to claim 3, wherein the first stage heating and the second stage heating are performed using separate heating coils.

The partial heat treatment method for a heat treatment member according to claim 4, wherein the heating coil for performing the first stage heating and the heating coil for performing the second stage heating have different shapes.

The partial heat treatment method for a heat treatment member according to claim 4, wherein the heating coil for performing the first stage heating and the heating coil for performing the second stage heating have the same shape.

The partial heat treatment method for a heat treatment member according to claim 3, wherein the first stage heating and the second stage heating are performed using the same heating coil.

The partial heat treatment method for a heat treatment member according to claim 1, wherein one heating coil heats two heat treatment members.

The partial heat treatment method for a heat treatment member according to claim 1, wherein in the cooling step, the entire heat treatment member is immersed in a fixed position in a cooling liquid in a cooling liquid tank to be stationary.

The partial heat treatment method for a heat treatment member according to claim 1, wherein in the cooling step, a coolant flow that flows out from a jet jacket is jetted to the specific portion.

The partial heat treatment method for a heat treatment member according to claim 1, wherein the heat treatment member is an endless track link.

The partial heat treatment method for a heat treatment member according to claim 11, wherein the specific portion is a roller tread portion of the link.