JP6977339B2 - Heat treatment method for steel parts - Google Patents
Heat treatment method for steel parts Download PDFInfo
- Publication number
- JP6977339B2 JP6977339B2 JP2017132048A JP2017132048A JP6977339B2 JP 6977339 B2 JP6977339 B2 JP 6977339B2 JP 2017132048 A JP2017132048 A JP 2017132048A JP 2017132048 A JP2017132048 A JP 2017132048A JP 6977339 B2 JP6977339 B2 JP 6977339B2
- Authority
- JP
- Japan
- Prior art keywords
- temperature
- heat treatment
- steel
- furnace
- steel component
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Heat Treatment Of Articles (AREA)
Description
本発明は、鋼材部品の熱処理方法に関するものである。 The present invention relates to a heat treatment method for steel parts.
鋼材部品の焼入れは、鋼材部品を高温状態とした後に急冷してマルテンサイト組織を得る熱処理技術である。これにより、鋼材部品の表面に硬く緻密なマルテンサイト組織が形成され、部品表面の耐摩耗性と衝撃強度が向上する。焼入れにあたっては、鋼材部品を一旦高温にする必要があるが、この際に機械加工などの前工程で与えられた残留応力（微細歪）が解放され、鋼材部品が変形する。このため、前工程の加工条件の変動に応じて、加工完了から焼入れ完了までの熱処理歪も変動するという問題がある。この種の残留応力を小さくする方法として、プレス加工時のプレス型に高硬度の表面処理被膜を製膜し，高速でせん断加工することにより金属薄板に付加された残留応力を極小化するものが知られている（特許文献１）。 Quenching of steel parts is a heat treatment technique for obtaining a martensite structure by quenching the steel parts after heating them to a high temperature. As a result, a hard and dense martensite structure is formed on the surface of the steel material component, and the wear resistance and impact strength of the component surface are improved. In quenching, it is necessary to temporarily heat the steel parts to a high temperature, but at this time, the residual stress (fine strain) given in the previous process such as machining is released, and the steel parts are deformed. Therefore, there is a problem that the heat treatment strain from the completion of machining to the completion of quenching also fluctuates according to the fluctuation of the machining conditions in the previous process. As a method of reducing this kind of residual stress, a method of forming a high-hardness surface-treated film on a press die during press working and shearing at high speed to minimize the residual stress applied to the thin metal plate. It is known (Patent Document 1).
しかしながら、上述した従来方法ではプレス型に高硬度の表面処理被膜を形成する前処理が必要となり、こうした前処理にコストや時間を要するという問題がある。 However, the above-mentioned conventional method requires a pretreatment for forming a high-hardness surface treatment film on the press mold, and there is a problem that such pretreatment requires cost and time.
本発明が解決しようとする課題は、前工程で生じた残留応力を時間やコストをかけずに除去できる鋼材部品の熱処理方法を提供することである。 An object to be solved by the present invention is to provide a heat treatment method for steel parts, which can remove residual stress generated in a previous step without spending time and cost.
本発明は、可変圧縮比エンジンのクランクシャフトに取り付けられるマルチリンク部品からなる鋼材部品であり、他の鋼材部品とネジ孔に形成したネジにネジを締め付けることで対となり、両鋼材部品を接合して前記クランクシャフトに取り付けられる鋼材部品の熱処理方法において、予め一定の熱容量を有する炉内雰囲気を形成したのち、この熱処理炉に室温状態の鋼材部品を投入し、炉内雰囲気の温度と鋼材部品の温度とが平衡する温度で鋼材部品を５〜１５分保持したのち、鋼材部品を浸炭温度まで昇温し、浸炭処理した鋼材部品をネジ研削し、ネジ孔を形成することによって上記課題を解決する。 The present invention is a steel component composed of multi-link components attached to the crank shaft of a variable compression ratio engine, and is paired with other steel components by tightening a screw to a screw formed in a screw hole to join both steel components. In the heat treatment method for steel parts attached to the crank shaft, an atmosphere inside the furnace having a certain heat capacity is formed in advance, and then the steel parts at room temperature are put into this heat treatment furnace to adjust the temperature of the atmosphere inside the furnace and the steel parts. After holding the steel parts at a temperature that is in equilibrium with the temperature for 5 to 15 minutes, the temperature of the steel parts is raised to the carburizing temperature, and the carburized steel parts are screw-ground to form screw holes to solve the above problems. ..
本発明によれば、鋼材部品を熱処理温度まで昇温する前に、当該熱処理温度より低い温度で鋼材部品を所定時間保持することにより、熱処理前に鋼材部品の残留応力を除去することができる。これにより、前工程で生じた残留応力を時間やコストをかけずに除去できる鋼材部品の熱処理方法を提供することができる。 According to the present invention, the residual stress of the steel component can be removed before the heat treatment by holding the steel component at a temperature lower than the heat treatment temperature for a predetermined time before raising the temperature of the steel component to the heat treatment temperature. This makes it possible to provide a heat treatment method for steel parts that can remove the residual stress generated in the previous process without spending time and cost.
以下、本発明の実施形態を図面に基づいて説明する。図１は、本発明に係る鋼材部品の熱処理方法に適用される鋼材部品の一例を示す斜視図である。図示する鋼材部品１は、可変圧縮比エンジンのマルチリンクを構成する部品である。このマルチリンクは、たとえば特開２０１７−０８８９２２の図６及び図７に記載されたように、一対の鋼材部品１が相互に対称に組み合わされてネジで結合された構成であり、クランクシャフトを回転軸として圧縮比を変更する分だけ回転する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of a steel component applied to the heat treatment method for a steel component according to the present invention. The illustrated steel component 1 is a component constituting the multi-link of the variable compression ratio engine. This multi-link has, for example, as described in FIGS. 6 and 7 of Japanese Patent Laid-Open No. 2017-08892, in which a pair of steel parts 1 are symmetrically combined with each other and connected by a screw to rotate a crankshaft. It rotates as an axis by changing the compression ratio.
鋼材部品１は、半円形状の軸受部１１と、一対のピン圧入部１２と、ネジ部１３とを備える。一対のピン圧入部１２とネジ部１３との間に軸受部１１が設けられている。軸受部１１は、クランクシャフトの軸受を構成する。一対のピン圧入部１２は、アッパーリンク又はコントロールリンクを連結するためのピンを圧入する孔を有する。ネジ部１３は、ネジを螺合させるネジ孔１３Ａを有する。図示は省略するが、一対のピン圧入部１２の間にはネジが挿通されるネジ孔が形成されており、このネジ孔に挿通されたネジが、他方の鋼材部品１のネジ孔１３Ａに螺合する。
The steel component 1 includes a semicircular bearing
図２は、本発明に係る鋼材部品１の熱処理方法が適用される鋼材部品１の製造方法を示す工程図である。同図に示すように、本実施形態の鋼材部品１の製造方法では、まず、ステップＳ１において、図示しない原材料を鍛造加工してリンク形状の外形を有する鋼材部品１を形成する。この鍛造加工では、鋼材部品１のネジ部１３に、ネジ溝の無い孔１３Ｂを形成する。次に、ステップＳ２において、面削加工を実施し、鋼材部品１の表面の黒皮を除去する。こうした鍛造及び面削などの機械加工により、得られた鋼材部品１には残留応力が生じる。
FIG. 2 is a process diagram showing a manufacturing method of the steel component 1 to which the heat treatment method of the steel component 1 according to the present invention is applied. As shown in the figure, in the method for manufacturing a steel component 1 of the present embodiment, first, in step S1, a raw material (not shown) is forged to form a steel component 1 having a link-shaped outer shape. In this forging process, a hole 13B without a thread groove is formed in the threaded
次に、ステップＳ３において、鋼材部品１の表面全体に対して表面硬化処理を実施し、鋼材部品１の表面全体を熱処理により硬化させる。表面硬化処理としては、焼入れ、浸炭焼入れ、窒化焼入れ又は浸炭窒化焼入れ等の熱処理が挙げられる。以下、図３において、鋼材部品１の材料が、クロム鋼鋼材ＳＣｒ４２０Ｈからなり、鋼材部品１の表面全体に対して浸炭焼入れを行うものとして具体的な温度を例示しつつ、本発明に係る熱処理を説明する。なお、クロム鋼鋼材ＳＣｒ４２０Ｈとは、鉄以外の成分として、Ｃを０．１７〜０．２３重量％，Ｃｒを０．８５〜１．２０重量％，Ｓｉを０．１５〜０．３５重量％，Ｍｎを０．６０〜１．００重量％，Ｐを０．０３重量％以下，Ｓを０．０３重量％以下，Ｎｉを０．２５重量％以下、Ｃｕを０．３重量％以下含む鋼材である。ただし、本発明に係る鋼材部品はクロム鋼鋼材にのみ限定されず他の鋼材をも用いることができる。また、クロム鋼鋼材からなる場合であっても、例示する温度には何ら限定されるものではない。 Next, in step S3, the entire surface of the steel component 1 is subjected to surface hardening treatment, and the entire surface of the steel component 1 is cured by heat treatment. Examples of the surface hardening treatment include heat treatments such as quenching, carburizing and quenching, nitriding and nitriding, and carburizing and nitriding and quenching. Hereinafter, in FIG. 3, the material of the steel component 1 is made of chromium steel SCr420H, and the heat treatment according to the present invention is performed while exemplifying a specific temperature assuming that the entire surface of the steel component 1 is carburized and quenched. explain. The chrome steel material SCr420H contains 0.17 to 0.23% by weight of C, 0.85 to 1.20% by weight of Cr, and 0.15 to 0.35% by weight of Si as components other than iron. , Mn is 0.60 to 1.00% by weight, P is 0.03% by weight or less, S is 0.03% by weight or less, Ni is 0.25% by weight or less, and Cu is 0.3% by weight or less. Is. However, the steel parts according to the present invention are not limited to the chromium steel material, and other steel materials can also be used. Further, even if it is made of chrome steel, the temperature is not limited to the example.
図３は、本実施形態の表面硬化熱処理の一例である処理内容、処理時間及び処理温度の関係を示す図である。本実施形態の表面硬化熱処理は、図３の時間ｔ３〜ｔ８の浸炭焼入れ処理を行う前に、時間ｔ０〜ｔ１において、熱処理炉内を第１所定温度Ｔ１まで昇温させて一定の熱容量Ｑ１を有する炉内雰囲気を形成したのち、時間ｔ１において熱処理炉に室温状態（たとえば０〜３５℃）の鋼材部品１を投入し、時間ｔ１〜ｔ３において、第１所定温度Ｔ１より低い、熱処理炉内の雰囲気の温度と鋼材部品１の温度とが平衡する第２所定温度Ｔ２で、鋼材部品１を所定時間ｔｍ１保持する。 FIG. 3 is a diagram showing the relationship between the treatment content, the treatment time, and the treatment temperature, which is an example of the surface hardening heat treatment of the present embodiment. In the surface hardening heat treatment of the present embodiment, the inside of the heat treatment furnace is heated to the first predetermined temperature T1 at the time t0 to t1 before the carburizing and quenching treatment of the time t3 to t8 in FIG. 3 to obtain a constant heat capacity Q1. After forming the atmosphere in the furnace, the steel component 1 at room temperature (for example, 0 to 35 ° C.) is put into the heat treatment furnace at time t1, and the temperature inside the heat treatment furnace is lower than the first predetermined temperature T1 at times t1 to t3. The steel component 1 is held at tm1 for a predetermined time at a second predetermined temperature T2 in which the temperature of the atmosphere and the temperature of the steel component 1 are in equilibrium.
本実施形態で用いられる熱処理炉としては、従来公知の浸炭炉を用いることができ、時間ｔ０〜ｔ１において、当該熱処理炉内を第１所定温度Ｔ１まで昇温させて一定の熱容量Ｑ１を有する炉内雰囲気を形成する。この第１所定温度Ｔ１は、熱処理炉内の熱容量と、時間ｔ１にて投入される鋼材部品１の総熱量Ｑ２と、平衡温度たる第２所定温度Ｔ２とに応じて定められる。ここで、一定の熱容量Ｑ１を有する炉内雰囲気を形成するための第１所定温度Ｔ１は、熱処理炉内の雰囲気の温度と鋼材部品１の温度とが平衡する第２所定温度Ｔ２が、好ましくは、その鋼材部品１の再結晶温度Ｔｒｃ±１００℃の範囲内になるように定められる。すなわち、熱処理炉の熱容量Ｑ１は、既知である炉内雰囲気ガスの比熱及び重量と第１温度Ｔ１により定まり、投入される鋼材部品１の総熱容量Ｑ２は、生産工程の仕様（鋼材部品1の比熱、重量及び熱処理炉に幾つの鋼材部品１が投入されるか）により定まり、鋼材部品１の再結晶温度Ｔｒｃは既知であることから、これらの数値を用いて理論式又はシミュレーション又は実験によって第１所定温度Ｔ１を求めることができる。以下、本例の場合においては、鋼材部品１の再結晶温度Ｔｒｃを６５０℃、第２所定温度を５５０〜７５０℃、熱処理炉の熱容量Ｑ１と鋼材部品１の総熱容量Ｑ２から第１所定温度Ｔ１を１０５０℃とするものとする。 As the heat treatment furnace used in the present embodiment, a conventionally known carburizing furnace can be used, and the inside of the heat treatment furnace is heated to a first predetermined temperature T1 at time t0 to t1 to have a constant heat capacity Q1. Form an inner atmosphere. The first predetermined temperature T1 is determined according to the heat capacity in the heat treatment furnace, the total heat amount Q2 of the steel component 1 charged at time t1, and the second predetermined temperature T2 which is the equilibrium temperature. Here, the first predetermined temperature T1 for forming the atmosphere in the furnace having a constant heat capacity Q1 is preferably the second predetermined temperature T2 in which the temperature of the atmosphere in the heat treatment furnace and the temperature of the steel component 1 are in equilibrium. , The recrystallization temperature of the steel component 1 is set to be within the range of Trc ± 100 ° C. That is, the heat capacity Q1 of the heat treatment furnace is determined by the known specific heat and weight of the atmosphere gas in the furnace and the first temperature T1, and the total heat capacity Q2 of the steel component 1 to be input is the specification of the production process (specific heat of the steel component 1). , The weight and how many steel parts 1 are put into the heat treatment furnace), and since the recrystallization temperature Trc of the steel parts 1 is known, the first method is based on a theoretical formula, simulation, or experiment using these values. The predetermined temperature T1 can be obtained. Hereinafter, in the case of this example, the recrystallization temperature Trc of the steel component 1 is 650 ° C, the second predetermined temperature is 550 to 750 ° C, the heat capacity Q1 of the heat treatment furnace and the total heat capacity Q2 of the steel component 1 to the first predetermined temperature T1. Is 1050 ° C.
熱処理炉内を１０５０℃まで昇温して一定の熱容量Ｑ１を有する炉内雰囲気を形成したら、この熱処理炉内に鋼材部品１を投入する。鋼材部品１を投入したのちは、熱処理炉への熱量の印加を中断し、熱容量Ｑ１の炉内雰囲気と総熱容量Ｑ２の鋼材部品１との間の熱交換のみにより鋼材部品１を第２所定温度Ｔ２、すなわち再結晶温度Ｔｒｃまで昇温する。上述したとおり、第１所定温度Ｔ１は、熱処理炉内の雰囲気の温度と鋼材部品１の温度とが第２所定温度Ｔ２で平衡するように設定されていることから、時間ｔ１から時間ｔ２の間において炉内雰囲気の温度が降下すると同時に鋼材部品１の温度が上昇し、時間ｔ２において両者の温度が平衡する。そして、熱処理炉内は実質的に断熱空間であるため、この両者の温度が平衡した状態を所定時間ｔｍ１保持する。本例において、所定時間ｔｍ１は、５〜１５分である。 After the temperature inside the heat treatment furnace is raised to 1050 ° C. to form an atmosphere in the furnace having a constant heat capacity Q1, the steel component 1 is put into the heat treatment furnace. After the steel component 1 is charged, the application of the amount of heat to the heat treatment furnace is interrupted, and the steel component 1 is brought to the second predetermined temperature only by heat exchange between the atmosphere inside the furnace having the heat capacity Q1 and the steel component 1 having the total heat capacity Q2. The temperature is raised to T2, that is, the recrystallization temperature Trc. As described above, the first predetermined temperature T1 is set between the time t1 and the time t2 because the temperature of the atmosphere in the heat treatment furnace and the temperature of the steel component 1 are set to be balanced at the second predetermined temperature T2. At the same time as the temperature of the atmosphere in the furnace drops, the temperature of the steel component 1 rises, and the temperatures of both are balanced at time t2. Since the inside of the heat treatment furnace is substantially a heat insulating space, the state in which the temperatures of both are in equilibrium is maintained at tm1 for a predetermined time. In this example, the predetermined time tm1 is 5 to 15 minutes.
時間ｔ４以降に行われる浸炭処理などの表面硬化処理の前に、鋼材部品１を再結晶温度Ｔｒｃで所定時間ｔｍ１保持することにより、鋼材部品１の表面が硬化する前に、図２の鍛造加工や面削加工で鋼材部品１に与えられた残留応力を除去することができる。これにより、浸炭処理などの表面硬化処理を施したときの熱処理歪が、前工程で与えられた残留応力によって影響を受けることを抑制することができる。また、一定の熱容量Ｑ１を有する炉内雰囲気に鋼材部品１を投入して、再結晶温度Ｔｒｃに平衡させることで、室温状態の炉内雰囲気に鋼材部品１を投入し、この室温状態から再結晶温度Ｔｒｃまで昇温する場合に比べ、短時間で再結晶温度Ｔｒｃまで昇温させることができる。 By holding the steel component 1 at the recrystallization temperature Trc for a predetermined time tm1 before the surface hardening treatment such as the carburizing treatment performed after the time t4, the forging process of FIG. 2 is performed before the surface of the steel component 1 is hardened. It is possible to remove the residual stress applied to the steel component 1 by surface cutting. As a result, it is possible to prevent the heat treatment strain when a surface hardening treatment such as carburizing treatment is performed from being affected by the residual stress given in the previous step. Further, by charging the steel component 1 into the atmosphere inside the furnace having a constant heat capacity Q1 and equilibrating it with the recrystallization temperature Trc, the steel component 1 is charged into the atmosphere inside the furnace at room temperature and recrystallized from this room temperature. The temperature can be raised to the recrystallization temperature Trc in a shorter time than in the case of raising the temperature to the temperature Trc.
鋼材部品１を再結晶温度Ｔｒｃ±１００℃で所定時間ｔｍ１保持し、残留応力を除去したら、続けて熱処理炉に熱量を再度印加して鋼材部品1を浸炭温度Ｔｃａまで昇温する（時間ｔ３〜ｔ４）。本例の浸炭温度Ｔｃａは、たとえば１０５０℃であり、この温度を（ｔ５−ｔ４）時間保持したのち、徐冷する（時間ｔ５〜ｔ６）。また本例では、浸炭処理後に焼入れ処理を施すが、この焼入れ処理では、時間ｔ６〜ｔ７において、鋼材部品１の金属組織がオーステナイト組織になる温度Ｔｑ、たとえば９００℃まで加熱して一定時間保持し、その後、鋼材部品１の金属組織がマルテンサイト組織になるように、熱処理炉のガス雰囲気中で急冷する（時間ｔ７〜ｔ８）。なお、上述した浸炭方法、焼入れ処理の加熱温度及び急冷方法は一実施例であり、何ら限定されるものではない。またステップＳ３の表面硬化熱処理に次いで、ステップＳ４においてネジ研削加工を実施する。本工程では、浸炭焼入れしたネジ部１３の孔１３Ｂをネジ研削することにより、ネジ部１３にネジ孔１３Ａを形成する。
The steel component 1 is held at a recrystallization temperature Trc ± 100 ° C. for a predetermined time at tm1, and after the residual stress is removed, heat is continuously applied to the heat treatment furnace again to raise the temperature of the steel component 1 to the carburizing temperature Tca (time t3 to ~). t4). The carburizing temperature Tca of this example is, for example, 1050 ° C., and this temperature is maintained for (t5-t4) hours and then slowly cooled (time t5-t6). Further, in this example, the quenching treatment is performed after the carburizing treatment. In this quenching treatment, the metal structure of the steel component 1 is heated to a temperature Tq where the metal structure of the steel component 1 becomes an austenite structure, for example, 900 ° C., and held for a certain period of time. After that, quenching is performed in the gas atmosphere of the heat treatment furnace so that the metal structure of the steel component 1 becomes a martensite structure (time t7 to t8). The carburizing method, the heating temperature of the quenching treatment, and the quenching method described above are examples, and are not limited in any way. Further, following the surface hardening heat treatment in step S3, screw grinding is performed in step S4. In this step, the hole 13B of the carburized and
図４は、図２のステップＳ３の表面硬化熱処理の他の例である処理内容、処理時間及び処理温度の関係を示す図である。図３に示す実施形態では、表面硬化熱処理として浸炭焼入れ処理を行ったが、本実施形態では表面硬化熱処理として焼入れ処理を行う。本例においても、表面硬化熱処理である焼入れ前に、鋼材部品１を第２所定温度で所定時間ｔｍ１保持し、前工程の機械加工により鋼材部品１に与えられた残留応力を除去する。 FIG. 4 is a diagram showing the relationship between the treatment content, the treatment time, and the treatment temperature, which is another example of the surface hardening heat treatment in step S3 of FIG. In the embodiment shown in FIG. 3, the carburizing and quenching treatment is performed as the surface hardening heat treatment, but in the present embodiment, the quenching treatment is performed as the surface hardening heat treatment. Also in this example, the steel component 1 is held at a second predetermined temperature for a predetermined time at tm1 before quenching, which is a surface hardening heat treatment, and the residual stress applied to the steel component 1 by the machining in the previous step is removed.
すなわち、図４の時間ｔ３〜ｔ５の焼入れ処理を行う前に、時間ｔ０〜ｔ１において、熱処理炉内を第１所定温度Ｔ１まで昇温させて一定の熱容量Ｑ１を有する炉内雰囲気を形成したのち、時間ｔ１において熱処理炉に室温状態（たとえば０〜３５℃）の鋼材部品１を投入し、時間ｔ１〜ｔ３において、第１所定温度Ｔ１より低い、熱処理炉内の雰囲気の温度と鋼材部品１の温度とが平衡する第２所定温度Ｔ２で、鋼材部品１を所定時間ｔｍ１保持する。第１所定温度Ｔ１の設定は、図３に示す実施形態と同様に、熱処理炉内の雰囲気の温度と鋼材部品１の温度とが平衡する第２所定温度Ｔ２が、好ましくは、その鋼材部品１の再結晶温度Ｔｒｃ±１００℃の範囲内になるように定められる。 That is, before the quenching treatment of the time t3 to t5 of FIG. 4, the inside of the heat treatment furnace is heated to the first predetermined temperature T1 at the time t0 to t1 to form an atmosphere in the furnace having a constant heat capacity Q1. At time t1, the steel component 1 at room temperature (for example, 0 to 35 ° C.) was charged into the heat treatment furnace, and at time t1 to t3, the temperature of the atmosphere in the heat treatment furnace and the temperature of the steel component 1 lower than the first predetermined temperature T1. At the second predetermined temperature T2 in which the temperature is in equilibrium, the steel component 1 is held at tm1 for a predetermined time. Similar to the embodiment shown in FIG. 3, the first predetermined temperature T1 is set to the second predetermined temperature T2 in which the temperature of the atmosphere in the heat treatment furnace and the temperature of the steel component 1 are in equilibrium, preferably the steel component 1. The recrystallization temperature of Trc is set to be within the range of ± 100 ° C.
熱処理炉内を１０５０℃まで昇温して一定の熱容量Ｑ１を有する炉内雰囲気を形成したら、この熱処理炉内に鋼材部品１を投入する。鋼材部品１を投入したのちは、熱処理炉への熱量の印加を中断し、熱容量Ｑ１の炉内雰囲気と総熱容量Ｑ２の鋼材部品１との間の熱交換のみにより鋼材部品１を第２所定温度Ｔ２、すなわち再結晶温度Ｔｒｃまで昇温する。上述したとおり、第１所定温度Ｔ１は、熱処理炉内の雰囲気の温度と鋼材部品１の温度とが第２所定温度Ｔ２で平衡するように設定されていることから、時間ｔ１から時間ｔ２の間において炉内雰囲気の温度が降下すると同時に鋼材部品１の温度が上昇し、時間ｔ２において両者の温度が平衡する。そして、熱処理炉内は実質的に断熱空間であるため、この両者の温度が平衡した状態を所定時間ｔｍ１保持する。本例において、所定時間ｔｍ１は、５〜１５分である。 After the temperature inside the heat treatment furnace is raised to 1050 ° C. to form an atmosphere in the furnace having a constant heat capacity Q1, the steel component 1 is put into the heat treatment furnace. After the steel component 1 is charged, the application of the amount of heat to the heat treatment furnace is interrupted, and the steel component 1 is brought to the second predetermined temperature only by heat exchange between the atmosphere inside the furnace having the heat capacity Q1 and the steel component 1 having the total heat capacity Q2. The temperature is raised to T2, that is, the recrystallization temperature Trc. As described above, the first predetermined temperature T1 is set between the time t1 and the time t2 because the temperature of the atmosphere in the heat treatment furnace and the temperature of the steel component 1 are set to be balanced at the second predetermined temperature T2. At the same time as the temperature of the atmosphere in the furnace drops, the temperature of the steel component 1 rises, and the temperatures of both are balanced at time t2. Since the inside of the heat treatment furnace is substantially a heat insulating space, the state in which the temperatures of both are in equilibrium is maintained at tm1 for a predetermined time. In this example, the predetermined time tm1 is 5 to 15 minutes.
時間ｔ３以降に行われる焼入れ処理などの表面硬化処理の前に、鋼材部品１を再結晶温度Ｔｒｃで所定時間ｔｍ１保持することにより、鋼材部品１の表面が硬化する前に、図２の鍛造加工や面削加工で鋼材部品１に与えられた残留応力を除去することができる。これにより、浸炭処理などの表面硬化処理を施したときの熱処理歪が、前工程で与えられた残留応力によって影響を受けることを抑制することができる。また、一定の熱容量Ｑ１を有する炉内雰囲気に鋼材部品１を投入して、再結晶温度Ｔｒｃに平衡させることで、室温状態の炉内雰囲気に鋼材部品１を投入し、この室温状態から再結晶温度Ｔｒｃまで昇温する場合に比べ、短時間で再結晶温度Ｔｒｃまで昇温させることができる。 By holding the steel component 1 at the recrystallization temperature Trc for a predetermined time tm1 before the surface hardening process such as the quenching process performed after the time t3, the forging process of FIG. 2 is performed before the surface of the steel component 1 is cured. It is possible to remove the residual stress applied to the steel component 1 by the surface cutting process. As a result, it is possible to prevent the heat treatment strain when a surface hardening treatment such as carburizing treatment is performed from being affected by the residual stress given in the previous step. Further, by charging the steel component 1 into the atmosphere inside the furnace having a constant heat capacity Q1 and equilibrating it with the recrystallization temperature Trc, the steel component 1 is charged into the atmosphere inside the furnace at room temperature and recrystallized from this room temperature. The temperature can be raised to the recrystallization temperature Trc in a shorter time than in the case of raising the temperature to the temperature Trc.
鋼材部品１を再結晶温度Ｔｒｃ±１００℃で所定時間ｔｍ１保持し、残留応力を除去したら、続けて熱処理炉に熱量を再度印加し、鋼材部品１の金属組織がオーステナイト組織になる温度Ｔｑ、たとえば９００℃まで加熱して一定時間保持し、その後、鋼材部品１の金属組織がマルテンサイト組織になるように、熱処理炉のガス雰囲気中で急冷する（時間ｔ３〜ｔ５）。またステップＳ３の表面硬化熱処理に次いで、ステップＳ４においてネジ研削加工を実施する。本工程では、浸炭焼入れしたネジ部１３の孔１３Ｂをネジ研削することにより、ネジ部１３にネジ孔１３Ａを形成する。
After holding the steel component 1 at a recrystallization temperature Trc ± 100 ° C. for a predetermined time at tm1 and removing the residual stress, the heat treatment is subsequently applied again to the heat treatment furnace, and the temperature Tq at which the metal structure of the steel component 1 becomes an austenite structure, for example. It is heated to 900 ° C. and held for a certain period of time, and then rapidly cooled in the gas atmosphere of the heat treatment furnace so that the metal structure of the steel component 1 becomes a martensite structure (time t3 to t5). Further, following the surface hardening heat treatment in step S3, screw grinding is performed in step S4. In this step, the hole 13B of the carburized and
なお、上述した実施形態では、鋼材部品１を第２の所定温度Ｔ２で所定時間ｔｍ１保持する間は、熱処理炉に熱量を印加するのを中断したが、熱処理炉内の雰囲気温度が後工程で行われる浸炭温度や焼入れ温度に達しない範囲でならば熱処理炉に熱量を印加してもよい。 In the above-described embodiment, while the steel component 1 is held at the second predetermined temperature T2 for a predetermined time at tm1, the application of heat to the heat treatment furnace is interrupted, but the atmospheric temperature in the heat treatment furnace is changed in the subsequent step. A calorific value may be applied to the heat treatment furnace as long as it does not reach the carburizing temperature or the quenching temperature to be performed.
以上のとおり、本実施形態の熱処理方法によれば、焼入れ、浸炭焼入れ、窒化焼入れ又は浸炭窒化焼入れ等の表面硬化処理の前に、鋼材部品１を好ましくは再結晶温度Ｔｒｃ±１００℃で所定時間ｔｍ１保持することにより、鋼材部品１の表面が硬化する前に、図２の鍛造加工や面削加工で鋼材部品１に与えられた残留応力を除去することができる。これにより、浸炭処理などの表面硬化処理を施したときの熱処理歪が、前工程で与えられた残留応力によって影響を受けることを抑制することができる。 As described above, according to the heat treatment method of the present embodiment, before the surface hardening treatment such as quenching, carburizing quenching, nitriding quenching, or carburizing nitriding quenching, the steel component 1 is preferably recrystallized at a recrystallization temperature of Trc ± 100 ° C. for a predetermined time. By holding tm1, it is possible to remove the residual stress applied to the steel component 1 by the forging process and the face cutting process of FIG. 2 before the surface of the steel component 1 is hardened. As a result, it is possible to prevent the heat treatment strain when a surface hardening treatment such as carburizing treatment is performed from being affected by the residual stress given in the previous step.
また、本実施形態の熱処理方法によれば、一定の熱容量Ｑ１を有する炉内雰囲気に鋼材部品１を投入して、再結晶温度Ｔｒｃに平衡させることで、室温状態の炉内雰囲気に鋼材部品１を投入し、この室温状態から再結晶温度Ｔｒｃまで昇温する場合に比べ、短時間で再結晶温度Ｔｒｃまで昇温させることができる。 Further, according to the heat treatment method of the present embodiment, the steel component 1 is put into the atmosphere inside the furnace having a constant heat capacity Q1 and balanced with the recrystallization temperature Trc, so that the steel component 1 is brought into the atmosphere inside the furnace at room temperature. It is possible to raise the temperature to the recrystallization temperature Trc in a short time as compared with the case where the temperature is raised from this room temperature state to the recrystallization temperature Trc.
図１に示す鋼材部品１において、一対のピン圧入部１２の間隔Ｌが、機械加工による残留応力の影響を受け易く、浸炭焼入れ等の表面硬化熱処理後にこの間隔Ｌの寸法が変動する。従来の浸炭焼入れによる表面硬化熱処理を行うと、間隔Ｌの変形量の平均が０．７０ｍｍ、同じく変形量の標準偏差３σが１．４０ｍｍであるのに対し、同じ鋼材部品１に図３に示す本実施形態の熱処理方法を適用すると、間隔Ｌの変形量の平均が０．５０ｍｍ、同じく変形量の標準偏差３σが０．０８ｍｍとなった。この結果からも、浸炭焼入れ前に鋼材部品１に与えられた残留応力が充分に除去され、特にばらつき（標準偏差３σ）の点でその影響が著しく減少していることが確認された。
In the steel component 1 shown in FIG. 1, the interval L of the pair of pin press-fitting
１…鋼材部品
１１…軸受部
１２ピン圧入部
１３…ネジ部
１３Ａ…ネジ孔
1 ...
Claims (3)
熱処理炉内を第１所定温度まで昇温させて一定の熱容量を有する炉内雰囲気を形成したのち、
前記熱処理炉に室温状態の前記鋼材部品を投入し、
前記第１所定温度より低い、前記炉内雰囲気の温度と前記鋼材部品の温度とが平衡する第２所定温度で、前記鋼材部品を５〜１５分保持したのち、
前記鋼材部品を前記第２所定温度より高い浸炭温度まで加熱し、
前記浸炭処理した鋼材部品をネジ研削し、ネジ孔を形成する鋼材部品の熱処理方法。 It is a steel part consisting of multi-link parts attached to the crankshaft of a variable compression ratio engine. It is paired with other steel parts by tightening screws to the screws formed in the screw holes, and both steel parts are joined to join the crankshaft. In the heat treatment method of steel parts attached to
After raising the temperature inside the heat treatment furnace to the first predetermined temperature to form an atmosphere inside the furnace having a constant heat capacity,
Put the steel parts of room temperature state to the heat treatment furnace,
After holding the steel parts for 5 to 15 minutes at a second predetermined temperature at which the temperature of the atmosphere in the furnace and the temperature of the steel parts are in equilibrium, which is lower than the first predetermined temperature, the steel parts are held.
The steel parts are heated to a carburizing temperature higher than the second predetermined temperature, and then the steel parts are heated to a carburizing temperature higher than the second predetermined temperature.
A method for heat-treating a steel part that forms a screw hole by screw-grinding the carburized steel part.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017132048A JP6977339B2 (en) | 2017-07-05 | 2017-07-05 | Heat treatment method for steel parts |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017132048A JP6977339B2 (en) | 2017-07-05 | 2017-07-05 | Heat treatment method for steel parts |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2019014932A JP2019014932A (en) | 2019-01-31 |
| JP6977339B2 true JP6977339B2 (en) | 2021-12-08 |
Family
ID=65357117
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2017132048A Active JP6977339B2 (en) | 2017-07-05 | 2017-07-05 | Heat treatment method for steel parts |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP6977339B2 (en) |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS582588B2 (en) * | 1978-12-29 | 1983-01-17 | 日産自動車株式会社 | Gas carburizing pretreatment method and equipment |
| JPH07103417B2 (en) * | 1991-02-21 | 1995-11-08 | 日本発条株式会社 | Heating furnace and quenching and heating method for steel |
| JP4074929B2 (en) * | 2002-01-17 | 2008-04-16 | 関東冶金工業株式会社 | Operation method of continuous heating furnace |
| WO2016098143A1 (en) * | 2014-12-18 | 2016-06-23 | 新日鐵住金株式会社 | Method for manufacturing nitrided component and steel for nitriding |
| CN107801403B (en) * | 2015-06-24 | 2020-11-24 | 诺维尔里斯公司 | Fast response heater for use in conjunction with a metal processing furnace and related control system |
| KR101738503B1 (en) * | 2016-04-07 | 2017-05-22 | 한국생산기술연구원 | Method for heat treatment for reducing deformation of cold-work articles |
-
2017
- 2017-07-05 JP JP2017132048A patent/JP6977339B2/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| JP2019014932A (en) | 2019-01-31 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US20040025340A1 (en) | Fracture split method for connecting rod | |
| CN106319535B (en) | Heat treatment method for gear shaft | |
| CN104099518A (en) | Carburized part, method for manufacturing thereof, and steel for carburized part | |
| JP6977339B2 (en) | Heat treatment method for steel parts | |
| US4039354A (en) | Method of making Belleville springs | |
| US3964737A (en) | Belleville spring | |
| JP5371084B2 (en) | Heat treatment method for cylindrical parts | |
| US5297338A (en) | Method of connecting metal ring gear to metal boss portion | |
| JPH08295904A (en) | Preparation of cam for jointed cam shaft | |
| US5037490A (en) | Process for allowing pretreatment of assembled camshaft components | |
| JP5424298B2 (en) | Heat treatment method for cylindrical parts | |
| JP2006219706A (en) | Heat-treated iron based sintered component and method for producing the same | |
| JP2017020555A (en) | Method for manufacturing gear | |
| WO2018061087A1 (en) | Steel component manufacturing method | |
| KR101823890B1 (en) | Method for gas nitriding of steel | |
| JPH06100942A (en) | Production of piston pin | |
| JP4919556B2 (en) | Gear manufacturing method | |
| JP2827592B2 (en) | Manufacturing method of steel parts | |
| JP2019014931A (en) | Heat treatment method for steel material component | |
| JPH01112014A (en) | Connecting rod | |
| JPH0453937B2 (en) | ||
| JP2004308887A (en) | High strength connecting rod and manufacturing method thereof | |
| JP6228733B2 (en) | Induction hardening method of iron-based sintered body | |
| JP2007246975A (en) | Method of manufacturing steel shaft | |
| JP4421334B2 (en) | bearing |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20200512 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20201111 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20201124 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20210122 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20210316 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20210422 |
|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20210511 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20210806 |
|
| C60 | Trial request (containing other claim documents, opposition documents) |
Free format text: JAPANESE INTERMEDIATE CODE: C60 Effective date: 20210806 |
|
| A911 | Transfer to examiner for re-examination before appeal (zenchi) |
Free format text: JAPANESE INTERMEDIATE CODE: A911 Effective date: 20210816 |
|
| C21 | Notice of transfer of a case for reconsideration by examiners before appeal proceedings |
Free format text: JAPANESE INTERMEDIATE CODE: C21 Effective date: 20210817 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20211012 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20211025 |
|
| R151 | Written notification of patent or utility model registration |
Ref document number: 6977339 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R151 |