JP2005113217A

JP2005113217A - Heat treatment system

Info

Publication number: JP2005113217A
Application number: JP2003349679A
Authority: JP
Inventors: Hirokazu Nakajima; 碩一中島; Kikuo Maeda; 喜久男前田
Original assignee: NTN Corp; NTN Toyo Bearing Co Ltd
Current assignee: NTN Corp
Priority date: 2003-10-08
Filing date: 2003-10-08
Publication date: 2005-04-28

Abstract

<P>PROBLEM TO BE SOLVED: To restrain the irregularity in a heat treatment quality in each steel-made part and also, the unevenness in the heat treatment qualities in among the steel-made parts. <P>SOLUTION: A heating machine 21 in a secondary treating apparatus 2 is constituted of a preheating part 21a and a main heating part 21b. The heating part 21a is constituted of a high frequency induction heating apparatus, wherein bearing parts shifted from a primary treating apparatus 1 are heated piece by piece with induction heating (high frequency heating) and preheated to a secondary heating temperature T2 in the main heating part 21b or to the temperature near this temperature T2. Since each bearing part is preheated with the induction-heating (high frequency heating) in the preheating part 21a, the temperature of each bearing part for the main heating part 21b, is made uniform and stable. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、軸受部品等の鋼製部品に二段の熱処理を施す熱処理システムに関するものである。 The present invention relates to a heat treatment system that performs two-stage heat treatment on steel parts such as bearing parts.

例えば、減速機、ドライブピニオン、トランスミッション等に使用される軸受は、高荷重、潤滑剤への異物（ギヤの摩耗粉等）の混入など、厳しい条件下で運転されるが、近時の高速化や小型化等の要求に伴い、使用条件の厳しさの度合いは益々増大する傾向にある。このような近時の傾向に鑑み、下記の特許文献１では、転動疲労寿命、耐割れ強度、耐経年寸法変化という基本性能に優れた軸受部品を得ることができる熱処理方法を提供している。この熱処理方法は、軸受部品用の鋼をＡ₁変態点を越える浸炭窒化処理温度で浸炭窒化処理した後、Ａ₁変態点未満の温度に冷却し、その後、Ａ₁変態点以上で浸炭窒化処理の温度未満の焼入れ温度域（７９０℃〜８３０℃）に再加熱して焼入れを行うものである。 For example, bearings used in reduction gears, drive pinions, transmissions, etc. are operated under severe conditions such as high loads and foreign substances (gear wear powder, etc.) mixed in the lubricant. With the demand for miniaturization and the like, the severity of use conditions tends to increase more and more. In view of such a recent trend, Patent Document 1 below provides a heat treatment method capable of obtaining a bearing component that is excellent in basic performance such as rolling fatigue life, crack resistance strength, and aging change in dimensions. . The heat treatment method, after the carbonitriding steel for the bearing parts carbonitriding temperature exceeding the A ₁ transformation point, cooled to a temperature below the A ₁ transformation point, then, carbonitriding at A ₁ transformation point or more It quenches by reheating to the quenching temperature range (790 degreeC-830 degreeC) less than this temperature.

上記の熱処理方法によれば、熱処理後の軸受部品のミクロ組織におけるオーステナイト結晶粒が平均粒径で８μｍ以下にまで微細化され、軸受部品の転動疲労寿命、シャルピー衝撃値、破壊靭性値、圧壊強度などが向上し、基本性能に優れた軸受部品を得ることができる。 According to the above heat treatment method, the austenite crystal grains in the microstructure of the bearing part after heat treatment are refined to an average grain size of 8 μm or less, and the rolling fatigue life, Charpy impact value, fracture toughness value, crushing of the bearing part are reduced. Strength and the like can be improved, and a bearing component with excellent basic performance can be obtained.

特開２００３−２２６９１８号公報JP 2003-226918 A

本発明の課題は、軸受部品等の鋼製部品に上記の熱処理方法を施すための熱処理システムを提供することであり、特に、各鋼製部品に均質な熱処理を施すことができる熱処理システムを提供することである。 An object of the present invention is to provide a heat treatment system for performing the above heat treatment method on steel parts such as bearing parts, and in particular, to provide a heat treatment system capable of performing homogeneous heat treatment on each steel part. It is to be.

上記課題を解決するため、本発明は、鋼製部品をＡ₁変態点を越える一次加熱温度に加熱した後、Ａ₁変態点未満に冷却することにより表層部に窒素富化層を形成する一次処理装置と、該一次処理装置による熱処理を経た鋼製部品を、予熱手段により予熱し、Ａ₁変態点を越えかつ一次加熱温度未満の二次加熱温度に本加熱した後、Ａ₁変態点未満に冷却する二次処理装置とを備えた熱処理システムを提供する。 To solve the above problems, the present invention is one after heating the steel parts in the primary heating temperature in excess of A ₁ transformation point, to form a nitrogen-enriched layer in a surface portion by cooling to below the A ₁ transformation point-order a processing unit, a steel component which has undergone a heat treatment with the primary treatment unit, is preheated by preheating means, after the heating in the secondary heating temperature below beyond the a ₁ transformation point and primary heating temperature, a less than ₁ transformation point A heat treatment system including a secondary processing apparatus for cooling is provided.

一次処理装置において、鋼製部品をＡ₁変態点を越える一次加熱温度に加熱し、その表層部に窒素を拡散させて窒素富化層を形成した後、Ａ₁変態点未満に冷却し、その後、二次処理装置において、Ａ₁変態点を越えかつ一次加熱温度未満の二次加熱温度に本加熱して焼入れを行うので、熱処理後の鋼製部品のミクロ組織におけるオーステナイト結晶粒が微細化され、例えばＪＩＳＧ０５５１に規定されたオーステナイト結晶粒度試験方法による粒度番号が１０番を越える微細な結晶粒となる。これにより、転動疲労寿命、耐割れ強度、耐経年寸法変化に優れた鋼製部品を得ることができる。 In the primary treatment apparatus, the steel part is heated to a primary heating temperature exceeding the A ₁ transformation point, and after nitrogen is diffused in the surface layer portion to form a nitrogen-enriched layer, the steel part is cooled to below the A ₁ transformation point, and thereafter In the secondary processing apparatus, since the main heating is performed to a secondary heating temperature exceeding the A ₁ transformation point and lower than the primary heating temperature, the austenite crystal grains in the microstructure of the steel part after the heat treatment are refined. For example, fine crystal grains having a grain size number exceeding 10 according to the austenite grain size test method defined in JIS G0551 are obtained. Thereby, the steel components excellent in rolling fatigue life, crack resistance strength, and aging change in dimensions can be obtained.

また、二次処理装置において、鋼製部品の本加熱を行う前の段階で、各鋼製部品を予熱手段により予熱するので、本加熱時における各鋼製部品の温度が均一になり、かつ安定する。そのため、各鋼製部品における熱処理品質のむらや、鋼製部品間における熱処理品質のばらつきが少なく、均質で信頼性の高い鋼製部品を得ることができる。予熱手段としては、鋼製部品をピース・バイ・ピースで予熱する誘導加熱（高周波焼加熱）が好ましい。 Also, in the secondary processing equipment, each steel part is preheated by the preheating means before the main heating of the steel part, so that the temperature of each steel part at the time of the main heating becomes uniform and stable. To do. Therefore, there is little unevenness in the heat treatment quality in each steel part and variation in the heat treatment quality between the steel parts, and it is possible to obtain a steel part that is homogeneous and highly reliable. As the preheating means, induction heating (induction heating) in which steel parts are preheated piece by piece is preferable.

一次処理装置において、鋼製部品の表層部に窒素を拡散させて窒素富化層を形成する手段として、窒化、浸炭窒化があるが、加熱温度や脱炭防止を考慮すると浸炭窒化によるのが好ましい。とりわけ、コスト面や品質面などからガス浸炭窒化が好ましい。 Nitriding and carbonitriding are available as means for forming a nitrogen-enriched layer by diffusing nitrogen in the surface layer of steel parts in the primary processing apparatus. However, carbonitriding is preferred in consideration of heating temperature and prevention of decarburization. . In particular, gas carbonitriding is preferable from the viewpoint of cost and quality.

一次処理装置と二次処理装置は、何れも、鋼製部品を所要温度（一次加熱温度、二次加熱温度）に加熱するための加熱機と、その後に冷却するための冷却機とを基本構成として含んでいる。例えば、一次処理装置でガス浸炭窒化を行う場合、一次処理装置の加熱機としては、浸炭性ガスにアンモニアを添加した雰囲気ガス中で鋼製部品を加熱する加熱炉が使用される。この加熱炉は、連続式、バッチ式の如何を問わない。二次処理装置の加熱機は、予熱部と本加熱部とで構成される。予熱部は、例えば鋼製部品を誘導加熱（高周波加熱）により予熱するものであり、高周波加熱装置で構成される。本加熱部は、浸炭、窒化、浸炭窒化等の化学処理を伴わないで鋼製部品を加熱するものであれば良く、その種類や方式（連続式、バッチ式）の如何を問わない。また、一次処理装置および二次処理装置の冷却機における冷却方式は特に問わず、空冷、Ｎ₂ガス等によるガス冷、油冷、水冷、塩浴による冷却等、種々の方式を採用することができる。 The primary processing device and the secondary processing device are both basically composed of a heater for heating the steel parts to the required temperatures (primary heating temperature, secondary heating temperature) and a cooler for cooling after that. Includes as. For example, when gas carbonitriding is performed in a primary processing apparatus, a heating furnace that heats steel parts in an atmospheric gas obtained by adding ammonia to a carburizing gas is used as a heater of the primary processing apparatus. The heating furnace may be a continuous type or a batch type. The heater of the secondary processing apparatus is composed of a preheating unit and a main heating unit. A preheating part preheats, for example, steel parts by induction heating (high frequency heating), and is constituted by a high frequency heating device. The main heating unit may be any unit that heats steel parts without chemical treatment such as carburizing, nitriding, and carbonitriding, regardless of the type or method (continuous type, batch type). In addition, the cooling method in the coolers of the primary processing device and the secondary processing device is not particularly limited, and various methods such as air cooling, gas cooling with N ₂ gas, oil cooling, water cooling, salt bath cooling, etc. can be adopted. it can.

本発明によれば、二次処理装置において、鋼製部品の本加熱を行う前の段階で、各鋼製部品を予熱手段により予熱するので、本加熱時における各鋼製部品の温度が均一になり、かつ安定する。そのため、二次処理時の保持時間が短くても、各鋼製部品における熱処理品質のむらや、鋼製部品間における熱処理品質のばらつきが少なく、転動疲労寿命、耐割れ強度、耐経年寸法変化に優れ、かつ、均質で信頼性の高い鋼製部品を得ることができる。 According to the present invention, in the secondary processing apparatus, since each steel part is preheated by the preheating means in the stage before the main heating of the steel part, the temperature of each steel part at the time of the main heating is made uniform. Become stable. Therefore, even if the holding time during the secondary treatment is short, there is little unevenness in the heat treatment quality of each steel part, and there is little variation in the heat treatment quality between steel parts, resulting in changes in rolling fatigue life, crack resistance strength, and aging resistance. Excellent, homogeneous and reliable steel parts can be obtained.

以下、鋼製部品の一例として軸受部品を使用し、これに適用した本発明の一実施形態を説明する。 Hereinafter, an embodiment of the present invention applied to a bearing component as an example of a steel component will be described.

図１は、この実施形態に係る熱処理システムの構成を概念的に示している。この熱処理システムは、一次処理装置１と二次処理装置２とで構成される。図示しない鍛造、旋削等の成形工程で成形された軸受部品は、一次処理装置１および二次処理装置２に順次移送され、それぞれの装置で加熱・冷却されて二段の熱処理が施される。 FIG. 1 conceptually shows the configuration of the heat treatment system according to this embodiment. This heat treatment system includes a primary processing apparatus 1 and a secondary processing apparatus 2. Bearing parts formed in a forming process such as forging and turning (not shown) are sequentially transferred to the primary processing apparatus 1 and the secondary processing apparatus 2, heated and cooled by the respective apparatuses, and subjected to a two-stage heat treatment.

ここでいう軸受部品は、玉軸受、円すいころ軸受、円筒ころ軸受、針状ころ軸受等の転がり軸受の構成部品を意味する。図２は、一例として外輪４１、内輪４２、および転動体４３を主要な構成部品とする深溝玉軸受４を示しており、これら外輪４１・内輪４２および転動体４３がここでいう軸受部品に該当する。これら軸受部品の素材としては、ＳＵＪ２等の軸受鋼の他、Ｃ：０．６〜１．３ｗｔ％、Ｓｉ：０．３〜３．０ｗｔ％、Ｍｎ：０．２〜１．５ｗｔ％、Ｃｒ：０．３〜５．０ｗｔ％、Ｎｉ：０．１〜３ｗｔ％を含む（望ましくはＭｏ：０．０５〜０．２５ｗｔ％未満、Ｖ：０．０５〜１．０ｗｔ％をさらに含む）高温用の軸受鋼や、Ｃ：０．４〜０．８ｗｔ％、Ｓｉ：０．２〜０．９ｗｔ％、Ｍｎ：０．７〜１．３ｗｔ％、Ｃｒ：０．７ｗｔ％以下を含む中炭素鋼等も使用することができる。 A bearing component here means the components of rolling bearings, such as a ball bearing, a tapered roller bearing, a cylindrical roller bearing, and a needle roller bearing. FIG. 2 shows a deep groove ball bearing 4 having an outer ring 41, an inner ring 42, and a rolling element 43 as main components as an example, and the outer ring 41, the inner ring 42, and the rolling element 43 correspond to the bearing parts here. To do. As materials for these bearing parts, in addition to bearing steel such as SUJ2, C: 0.6 to 1.3 wt%, Si: 0.3 to 3.0 wt%, Mn: 0.2 to 1.5 wt%, Cr : 0.3 to 5.0 wt%, Ni: 0.1 to 3 wt% (desirably Mo: 0.05 to less than 0.25 wt%, V: 0.05 to 1.0 wt% further included) Bearing steel and medium carbon containing C: 0.4-0.8 wt%, Si: 0.2-0.9 wt%, Mn: 0.7-1.3 wt%, Cr: 0.7 wt% or less Steel or the like can also be used.

一次処理装置１は、加熱機１１、冷却機１２、および洗浄機１３で構成される。加熱機１１は、例えば、浸炭性ガスにアンモニアを添加した雰囲気ガス中で軸受部品を加熱する加熱炉で構成される。この加熱機１１において、軸受部品は、図３に示すように、Ａ₁変態点を越える一次加熱温度Ｔ１（８００℃〜９５０℃、例えば８５０℃）で所定時間（例えば４０分）加熱され、これにより活性状態の窒素が軸受部品の表層部に拡散して窒素富化層（この例では浸炭窒化層）が形成される。この一次加熱は、基本的には表面に窒素富化層を形成することを目的とするものであるから、少なくとも窒化すればよく、必ずしも浸炭は必要ではない。但し、条件よっては、例えば脱炭が懸念される場合や使用鋼材の炭素量が少なく、十分な硬度を確保できない場合等は、窒化の他に浸炭も不可欠となる。加熱後の軸受部品は、図３に示すように、冷却機１２にてＭｓ点以下に冷却（例えば油冷）され、さらに洗浄機１３に移送されて冷却液（例えば油）の洗浄除去が行われる。尚、冷却機１２では、Ｍｓ点以下の温度に冷却する他、５００℃程度で恒温保持してもよい。また、図１では、一次処理装置１の加熱機１１として、連続式の加熱炉を例示しているが、バッチ式の加熱炉を採用しても良い。さらに、図１では、一次処理装置１の冷却機１２として油冷を例示しているが、空冷、Ｎ₂ガス等によるガス冷、水冷を採用しても良い。この場合、冷却機１２において、軸受部品に対する冷却液の付着がなくなるか、水のみが付着するので、後続の洗浄機１３を省略して、冷却機１２から二次処理装置２の加熱機２１に軸受部品を直接移送する構成とすることができる。 The primary processing apparatus 1 includes a heater 11, a cooler 12, and a washing machine 13. The heater 11 is constituted by, for example, a heating furnace that heats bearing components in an atmospheric gas obtained by adding ammonia to a carburizing gas. In this heater 11, the bearing parts are heated for a predetermined time (for example, 40 minutes) at a primary heating temperature T1 (800 ° C. to 950 ° C., for example, 850 ° C.) exceeding the A ₁ transformation point, as shown in FIG. As a result, the activated nitrogen diffuses into the surface layer of the bearing component to form a nitrogen-enriched layer (carbonitriding layer in this example). Since this primary heating is basically intended to form a nitrogen-enriched layer on the surface, at least nitriding is sufficient, and carburization is not necessarily required. However, depending on conditions, for example, when decarburization is a concern or when the amount of carbon in the steel used is small and sufficient hardness cannot be ensured, carburizing is indispensable in addition to nitriding. As shown in FIG. 3, the heated bearing parts are cooled to the Ms point or less by the cooler 12 (for example, oil-cooled), and further transferred to the washing machine 13 for washing and removing the coolant (for example, oil). Is called. The cooler 12 may be kept at a constant temperature of about 500 ° C. in addition to cooling to a temperature below the Ms point. In FIG. 1, a continuous heating furnace is illustrated as the heater 11 of the primary processing apparatus 1, but a batch heating furnace may be employed. Furthermore, although oil cooling is illustrated as the cooler 12 of the primary processing apparatus 1 in FIG. 1, air cooling, gas cooling with N ₂ gas, or water cooling may be employed. In this case, in the cooler 12, the coolant does not adhere to the bearing parts, or only water adheres. Therefore, the subsequent cleaning machine 13 is omitted, and the cooler 12 moves to the heater 21 of the secondary processing device 2. It can be set as the structure which transfers a bearing component directly.

一次処理装置１による熱処理を経た軸受部品は、コンベヤ等の搬送手段を介して二次処理装置２に移送される。二次処理装置２は、加熱機２１、冷却機２２、洗浄機２３、および焼戻し機２４で構成される。加熱機２１は、予熱部２１ａと本加熱部２１ｂとで構成される。予熱部２１ａは、高周波加熱装置で構成され、一次処理装置１から移送されてきた軸受部品をピース・バイ・ピースで誘導加熱（高周波加熱）により加熱して、本加熱部２１ｂにおける二次加熱温度Ｔ２又はその近傍の温度まで予熱するものである。本加熱部２１ｂは、例えば、通常の電気炉等の加熱炉で構成される。図１では、本加熱部２１ｂとして、連続式の加熱炉を例示しているが、バッチ式の加熱炉を採用しても良い。この本加熱部２１ｂにおいて、軸受部品は、図３に示すように、Ａ₁変態点以上でかつ一次処理装置１での一次加熱温度Ｔ１未満の二次加熱温度Ｔ２（７９０℃〜８３０℃、例えば８００℃）で所定時間（例えば１０〜３０分）加熱される。この二次加熱温度Ｔ２は一次加熱温度Ｔ１よりも低温であるで、軸受部品のミクロ組織におけるオーステナイト結晶粒は微細化される。各軸受部品を予熱部２１ａで誘導加熱（高周波加熱）により予熱するので、本加熱部２１ｂにおける各軸受部品の温度が均一になり、短時間の保持でも安定する。本加熱部２１ｂで加熱された軸受部品は、図３に示すように、冷却機２２にてＭｓ点以下に冷却（例えば油冷）され、さらに洗浄機２３に移送されて冷却液の洗浄除去が行われる。その後、この軸受部品は焼戻し機２４に移送され、図３に示すような適当な温度Ｔ３（例えば１８０℃）で焼戻される。尚、焼戻し機２４は、二次処理装置２と分離して設置しても良い。また、冷却機２２を空冷、ガス冷、水冷方式とすることにより、洗浄機２３を省略することもできる。 The bearing parts that have undergone the heat treatment by the primary processing apparatus 1 are transferred to the secondary processing apparatus 2 via a conveying means such as a conveyor. The secondary processing apparatus 2 includes a heater 21, a cooler 22, a washing machine 23, and a tempering machine 24. The heater 21 includes a preheating unit 21a and a main heating unit 21b. The preheating part 21a is composed of a high-frequency heating device, and heats the bearing parts transferred from the primary processing device 1 by piece-by-piece by induction heating (high-frequency heating), and the secondary heating temperature in the main heating part 21b. It preheats to T2 or the temperature of the vicinity. The main heating unit 21b is configured by a heating furnace such as a normal electric furnace, for example. In FIG. 1, a continuous heating furnace is illustrated as the main heating unit 21b, but a batch heating furnace may be employed. In the main heating portion 21b, as shown in FIG. 3, the bearing component has a secondary heating temperature T2 (790 ° C. to 830 ° C., for example, which is higher than the A ₁ transformation point and lower than the primary heating temperature T1 in the primary processing apparatus 1. 800 ° C.) for a predetermined time (for example, 10 to 30 minutes). Since the secondary heating temperature T2 is lower than the primary heating temperature T1, the austenite crystal grains in the microstructure of the bearing component are refined. Since each bearing part is preheated by induction heating (high frequency heating) in the preheating part 21a, the temperature of each bearing part in the main heating part 21b becomes uniform, and is stable even if it is held for a short time. As shown in FIG. 3, the bearing component heated by the main heating unit 21 b is cooled (for example, oil-cooled) to the Ms point or less by the cooler 22, and further transferred to the washing machine 23 to remove the cooling liquid by washing. Done. Thereafter, the bearing component is transferred to a tempering machine 24 and tempered at an appropriate temperature T3 (for example, 180 ° C.) as shown in FIG. The tempering machine 24 may be installed separately from the secondary processing apparatus 2. Moreover, the washing machine 23 can be omitted by adopting an air cooling, gas cooling, or water cooling system for the cooling machine 22.

以上の過程で熱処理された軸受部品では、表層に窒素富化層（窒素含有量０．１〜０．７ｗｔ％）が形成されるため、Ｈｖ７００以上の高い表面硬度が得られ、かつ、ミクロ組織中のオーステナイト結晶粒が微細化されてその結晶粒度は１０番を越えるものとなる。また、軸受部品の破壊応力値２６５０ＭＰａ以上、鋼中の水素濃度０．５ｐｐｍ以下、残留オーステナイト量１３〜２５％であり、通常品を遥かに凌ぐ良好な物性値が得られる。従って、耐割れ強度、耐摩耗性等を向上させることができ、さらには転動疲労寿命の向上に顕著な効果が得られる。 In the bearing parts heat-treated in the above process, since a nitrogen-enriched layer (nitrogen content 0.1 to 0.7 wt%) is formed on the surface layer, a high surface hardness of Hv 700 or higher is obtained, and the microstructure The inside austenite crystal grains are refined, and the crystal grain size exceeds tenth. Further, the fracture stress value of the bearing component is 2650 MPa or more, the hydrogen concentration in the steel is 0.5 ppm or less, and the retained austenite amount is 13 to 25%, and good physical property values far exceeding ordinary products can be obtained. Accordingly, it is possible to improve the cracking resistance, wear resistance, etc., and to obtain a remarkable effect in improving the rolling fatigue life.

以上に述べた一次加熱温度Ｔ１、二次加熱温度Ｔ２、焼戻し温度Ｔ３は何れも鋼材として軸受鋼ＳＵＳＪ２を使用する場合を例示したものである。使用する鋼材の種類によっては、これらの温度Ｔ１、Ｔ２、Ｔ３は上記例示とは異なる温度をとる場合がある。また、以上の説明では熱処理の対象として軸受部品を例示したが、本発明はこれに限らず、高い転動疲労寿命や耐割れ強度等が要求される機械部品、例えば等速自在継手の構成部品、さらには鋼製部品一般に広く適用することができる。 The primary heating temperature T1, the secondary heating temperature T2, and the tempering temperature T3 described above exemplify the case where the bearing steel SUSJ2 is used as the steel material. Depending on the type of steel used, these temperatures T1, T2, and T3 may be different from the above examples. In the above description, bearing parts are exemplified as heat treatment targets. However, the present invention is not limited to this, and mechanical parts that require high rolling fatigue life, crack resistance strength, etc., for example, components of constant velocity universal joints. Furthermore, it can be widely applied to steel parts in general.

実施形態に係る熱処理システムの構成を概念的に示す図である。It is a figure which shows notionally the structure of the heat processing system which concerns on embodiment. 深溝玉軸受の断面図である。It is sectional drawing of a deep groove ball bearing. 上記熱処理システムにおける熱処理のサイクル図である。It is a cycle diagram of the heat processing in the said heat processing system.

符号の説明Explanation of symbols

１一次処理装置
２二次処理装置
４転がり軸受
１１加熱機（一次加熱）
１２冷却機
２１加熱機（二次加熱）
２１ａ予熱部
２１ｂ本加熱部
２２冷却機
４１外輪
４２内輪
４２転動体 DESCRIPTION OF SYMBOLS 1 Primary processing apparatus 2 Secondary processing apparatus 4 Rolling bearing 11 Heating machine (primary heating)
12 Cooling machine 21 Heating machine (secondary heating)
21a Preheating part 21b Main heating part 22 Cooler 41 Outer ring 42 Inner ring 42 Rolling element

Claims

鋼製部品をＡ₁変態点を越える一次加熱温度に加熱した後、Ａ₁変態点未満に冷却することにより表層部に窒素富化層を形成する一次処理装置と、該一次処理装置による熱処理を経た鋼製部品を、予熱手段により予熱し、Ａ₁変態点を越えかつ一次加熱温度未満の二次加熱温度に本加熱した後、Ａ₁変態点未満に冷却する二次処理装置とを備えた熱処理システム。 After the steel parts were heated to a primary heating temperature exceeding the A ₁ transformation point, a primary processing device for forming a nitriding layer on the surface layer portion by cooling to below the A ₁ transformation point, the heat treatment by the primary processing device the steel parts having undergone, preheated by preheating means, after the heating in the secondary heating temperature of less than a ₁ transformation point beyond and primary heating temperature, and a secondary treatment device for cooling to below the a ₁ transformation point Heat treatment system.

予熱手段が誘導加熱である請求項１記載の熱処理システム。 The heat treatment system according to claim 1, wherein the preheating means is induction heating.

一次処理装置が、ガス浸炭窒化させる加熱機を含む請求項１又は２記載の熱処理システム。 The heat treatment system according to claim 1 or 2, wherein the primary treatment apparatus includes a heater for gas carbonitriding.