JP5167553B2 - Nitrogen treatment method and nitrogen treatment apparatus - Google Patents

Nitrogen treatment method and nitrogen treatment apparatus Download PDF

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JP5167553B2
JP5167553B2 JP2005328285A JP2005328285A JP5167553B2 JP 5167553 B2 JP5167553 B2 JP 5167553B2 JP 2005328285 A JP2005328285 A JP 2005328285A JP 2005328285 A JP2005328285 A JP 2005328285A JP 5167553 B2 JP5167553 B2 JP 5167553B2
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JP2007131933A (en
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匠吾 成田
敬二 横瀬
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Dowa Thermotech Co Ltd
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Description

本発明は、浸窒処理方法及び浸窒処理装置に関する。   The present invention relates to a nitriding treatment method and a nitriding treatment apparatus.

特開平8−13125号公報(特許文献1)には、ガス浸窒処理装置の炉気制御方法として、次のプロセスを含む方法が記載されている。すなわち、
(1)処理炉内の残留アンモニア量を計測し、
(2)炉内残留アンモニアの前記計測値に従い、予め実験的に求めた炉内残留アンモニア量と被処理品中の窒素濃度との相関に基づいて前記被処理品中の窒素濃度を演算し、
(3)窒素濃度の前記演算値と窒素濃度の目標値とを比較して、
(4)前記炉内へのアンモニアガスの供給量を制御する、制御方法である。
特開平8−13125号公報
Japanese Patent Laid-Open No. 8-13125 (Patent Document 1) describes a method including the following process as a furnace air control method of a gas nitriding apparatus. That is,
(1) Measure the amount of residual ammonia in the treatment furnace,
(2) According to the measured value of the residual ammonia in the furnace, the nitrogen concentration in the article to be processed is calculated based on the correlation between the amount of residual ammonia in the furnace experimentally obtained and the nitrogen concentration in the article to be processed;
(3) Compare the calculated value of nitrogen concentration with the target value of nitrogen concentration,
(4) A control method for controlling a supply amount of ammonia gas into the furnace.
JP-A-8-13125

しかしながら、前記(2)の工程において、炉内残留アンモニア量と被処理品中の窒素濃度との相関関係は、被処理品の種類(鋼種)によって異なるので、同一の制御では被処理品に応じた所望の品質が得られないという問題がある。   However, in the process (2), the correlation between the amount of residual ammonia in the furnace and the nitrogen concentration in the product to be processed varies depending on the type (steel type) of the product to be processed. There is a problem that the desired quality cannot be obtained.

本発明は、前記の如き事情に鑑みてなされたもので、前記従来のものとは異なる方式で常に所望の窒素濃度を得ることができる、浸窒処理方法及び同装置を提案しようとするものである。   The present invention has been made in view of the circumstances as described above, and intends to propose a nitriding treatment method and apparatus capable of always obtaining a desired nitrogen concentration by a method different from the conventional one. is there.

本発明はまた、異なる種類の被処理品であっても、同一の制御方式で常に所望の窒素濃度を得ることができる、浸窒処理方法及び同装置を提案しようとするものである。   The present invention also proposes a nitriding treatment method and apparatus capable of always obtaining a desired nitrogen concentration with the same control method even for different types of articles to be treated.

前記課題を解決するため、本発明等は、浸窒雰囲気中のアンモニアガス分圧と、浸窒温度、さらには鋼材の種類および時間と、被処理品の処理後の表面窒素濃度の関係を見出し、目標とする鋼材の表面窒素濃度を設定すれば、同一の方式で所望の窒素濃度を容易に且つ確実に得ることができる処理方法およびその装置を発明した。   In order to solve the above-mentioned problems, the present invention and others have found the relationship between the ammonia gas partial pressure in the nitriding atmosphere, the nitriding temperature, the type and time of the steel material, and the surface nitrogen concentration after the treatment of the article to be treated. The present inventors have invented a processing method and apparatus capable of easily and surely obtaining a desired nitrogen concentration by the same method by setting the target surface nitrogen concentration of the steel material.

本発明に係る浸窒処理方法は、
(1)浸窒雰囲気中のアンモニアガス分圧と、前記雰囲気中に置かれた被処理品の窒素濃度との間の、前記雰囲気の温度に依存する相関関係を求めておき、
(2)実際の浸窒処理における雰囲気中のアンモニアガス分圧と、前記実際の雰囲気の温度と、を計測し、
(3)アンモニアガス分圧の前記計測値と、雰囲気の温度の前記計測値と、前記相関関係と、に基づいて、雰囲気が有する浸窒(窒化)能力(窒化ポテンシャル)を演算し、
(4)前記窒化ポテンシャルの演算値と被処理品の窒素濃度の目標値とを比較して、
(5)被処理品の窒素濃度が前記目標値となるように前記雰囲気中へのアンモニアガスの供給量を制御する浸窒処理方法であって、
前記相関関係が、
窒化ポテンシャル(%)
=a(T)×In(P NH3 )+b(T)
In:自然対数
NH3 :アンモニアガス分圧
a(T),b(T):浸窒温度Tに依存する変数
で表されることを特徴としている(請求項1)。
The nitriding method according to the present invention is:
(1) Finding a correlation depending on the temperature of the atmosphere between the partial pressure of ammonia gas in the nitriding atmosphere and the nitrogen concentration of the article to be processed placed in the atmosphere;
(2) Measure the ammonia gas partial pressure in the atmosphere in the actual nitriding treatment and the temperature of the actual atmosphere,
(3) Based on the measured value of the ammonia gas partial pressure, the measured value of the temperature of the atmosphere, and the correlation, the nitriding (nitriding) capability (nitriding potential) of the atmosphere is calculated,
(4) Compare the calculated value of the nitriding potential with the target value of the nitrogen concentration of the article to be processed,
(5) A nitriding treatment method for controlling a supply amount of ammonia gas into the atmosphere so that a nitrogen concentration of an article to be treated becomes the target value ,
The correlation is
Nitriding potential (%)
= A (T) x In ( PNH3 ) + b (T)
In: Natural logarithm
P NH3 : Ammonia gas partial pressure
a (T), b (T): Variables depending on the nitriding temperature T
Is characterized in in represented that (claim 1).

また、本発明の好適な実施の形態に係る浸窒処理方法は、
(イ)浸窒雰囲気中のアンモニアガス分圧と、前記雰囲気中に置かれた特定の被処理品の窒素濃度との間の、前記雰囲気の温度に依存する相関関係を求め、
(ロ)さらに被処理品の浸窒性を、被処理品の種類毎に、特定の被処理品の浸窒性を基準として関連付け、
(ハ)実際の浸窒処理における雰囲気中のアンモニアガス分圧と、前記実際の雰囲気の温度と、を計測し、
(ニ)アンモニアガス分圧の前記計測値と、雰囲気の温度の前記計測値と、前記相関関係と、前記関連付けと、に基づいて、雰囲気が有する浸窒(窒化)能力(窒化ポテンシャル)を演算し、
(ホ)前記窒化ポテンシャルの演算値と被処理品の窒素濃度の目標値とを比較して、
(ヘ)被処理品の窒素濃度が前記目標値となるように前記雰囲気中へのアンモニアガスの供給量を制御する浸窒処理方法であって、
前記相関関係が、
窒化ポテンシャル(%)
=a(T)×In(P NH3 )+b(T)
In:自然対数
NH3 :アンモニアガス分圧
a(T),b(T):浸窒温度Tに依存する変数
で表されることを特徴としている(請求項2)。
Moreover, the nitriding treatment method according to a preferred embodiment of the present invention includes:
(A) Obtaining a correlation depending on the temperature of the atmosphere between the partial pressure of ammonia gas in the nitriding atmosphere and the nitrogen concentration of a specific article to be treated placed in the atmosphere;
(B) Further, the nitriding properties of the products to be processed are related to the types of the products to be processed based on the nitriding properties of the specific products to be processed,
(C) Measure the ammonia gas partial pressure in the atmosphere in the actual nitriding treatment and the temperature of the actual atmosphere;
(D) Calculate the nitriding (nitriding) ability (nitriding potential) of the atmosphere based on the measured value of the ammonia gas partial pressure, the measured value of the ambient temperature, the correlation, and the correlation. And
(E) Comparing the calculated value of the nitriding potential with the target value of the nitrogen concentration of the product to be processed,
(F) a nitriding treatment method for controlling the supply amount of ammonia gas into the atmosphere so that the nitrogen concentration of the article to be treated becomes the target value ,
The correlation is
Nitriding potential (%)
= A (T) x In ( PNH3 ) + b (T)
In: Natural logarithm
P NH3 : Ammonia gas partial pressure
a (T), b (T): Variables depending on the nitriding temperature T
Is characterized in in represented that (claim 2).

前記処理方法によれば、被処理品の種類の如何にかかわらず、同一の方式で常に所望の品質の処理品を得ることができる。   According to the processing method, a processed product having a desired quality can always be obtained by the same method regardless of the type of the processed product.

好適な実施の一形態として、前記(3)または(ニ)のプロセスにおいて、浸窒処理時間の関数として示される時間補正を加味し、浸窒処理時間の長短にかかわらず前記(3)または(ニ)の演算値が被処理品の浸窒処理後の窒素濃度を示すようにせしめることもできる(請求項3)。   As a preferred embodiment, in the process (3) or (d), a time correction shown as a function of the nitriding time is taken into account, and the above (3) or ( It is also possible to make the calculated value of d) indicate the nitrogen concentration after the nitriding treatment of the article to be treated (Claim 3).

他の好適な実施の形態として、前記浸窒処理が浸炭をともなう浸炭窒化処理であるものとすることもできる(請求項)。 As another preferred embodiment, the nitriding treatment may be a carbonitriding treatment with carburizing (Claim 4 ).

本発明に係る浸窒処理装置は、装入された被処理品に浸窒処理を施すための処理炉と、該炉内へのアンモニアガスの供給量を制御する流量制御弁と、前記炉内に供給されるアンモニアガスの流量を検出する流量計と、前記炉内のアンモニアガス分圧を検出するアンモニアガス分析計と、前記炉内の温度を検出する温度センサと、前記流量制御弁を制御する制御装置と、を備えている浸窒処理装置である。そして、前記制御装置は、前記アンモニアガス分析計及び前記温度センサの各検出値と、前記炉内のアンモニアガス分圧と前記炉内に配置した被処理品の窒素濃度との間の、前記炉内の温度に依存する、予め求めた相関関係と、に基づいて、雰囲気が有する浸窒(窒化)能力(窒化ポテンシャル)を演算し、前記演算値と被処理品の窒素濃度の目標値とを比較して、被処理品の窒素濃度が前記目標値となるように前記流量制御弁を制御し、
前記予め求めた相関関係が、
窒化ポテンシャル(%)
=a(T)×In(P NH3 )+b(T)
In:自然対数
NH3 :アンモニアガス分圧
a(T),b(T):浸窒温度Tに依存する変数
で表されるものとされている(請求項)。
A nitriding apparatus according to the present invention includes a processing furnace for performing a nitriding process on a charged product, a flow rate control valve for controlling the supply amount of ammonia gas into the furnace, A flow meter for detecting the flow rate of ammonia gas supplied to the furnace, an ammonia gas analyzer for detecting the partial pressure of ammonia gas in the furnace, a temperature sensor for detecting the temperature in the furnace, and the flow control valve are controlled. A nitriding treatment device comprising a control device. And the said control apparatus is the said furnace between each detected value of the said ammonia gas analyzer and the said temperature sensor, the ammonia gas partial pressure in the said furnace, and the nitrogen concentration of the to-be-processed goods arrange | positioned in the said furnace Based on the correlation determined in advance depending on the temperature in the atmosphere, the nitriding (nitriding) capability (nitriding potential) of the atmosphere is calculated, and the calculated value and the target value of the nitrogen concentration of the article to be processed are calculated. In comparison, the flow control valve is controlled so that the nitrogen concentration of the product to be processed becomes the target value ,
The previously determined correlation is
Nitriding potential (%)
= A (T) x In ( PNH3 ) + b (T)
In: Natural logarithm
P NH3 : Ammonia gas partial pressure
a (T), b (T): Variables depending on the nitriding temperature T
In is the one represented (claim 5).

また、本発明の実施の一形態に係る浸窒処理装置は、装入された被処理品に浸窒処理を施すための処理炉と、該炉内へのアンモニアガスの供給量を制御する流量制御弁と、前記炉内に供給されるアンモニアガスの流量を検出する流量計と、前記炉内のアンモニアガス分圧を検出するアンモニアガス分析計と、前記炉内の温度を検出する温度センサと、前記流量制御弁を制御する制御装置と、を備えている浸窒処理装置であって、前記制御装置は、前記被処理品の種類についての情報と、前記アンモニアガス分析計及び前記温度センサの各検出値と、前記炉内のアンモニアガス分圧と前記炉内に配置した特定の被処理品の窒素濃度との間の、前記炉内の温度に依存する、予め求めた相関関係と、前記特定の被処理品の浸窒性を基準として被処理品の種類毎に数値化した被処理品の鋼材補正係数と、に基づいて、雰囲気が有する浸窒(窒化)能力(窒化ポテンシャル)を演算し、前記演算値と被処理品の窒素濃度の目標値とを比較して、被処理品の窒素濃度が前記目標値となるように前記流量制御弁を制御し、
前記予め求めた相関関係が、
窒化ポテンシャル(%)
=a(T)×In(P NH3 )+b(T)
In:自然対数
NH3 :アンモニアガス分圧
a(T),b(T):浸窒温度Tに依存する変数
で表されるものとされている(請求項)。
Further, a nitriding apparatus according to an embodiment of the present invention includes a processing furnace for performing a nitriding process on a charged article to be processed, and a flow rate for controlling a supply amount of ammonia gas into the furnace. A control valve, a flow meter for detecting the flow rate of ammonia gas supplied into the furnace, an ammonia gas analyzer for detecting the partial pressure of ammonia gas in the furnace, and a temperature sensor for detecting the temperature in the furnace And a control device that controls the flow rate control valve, wherein the control device includes information on the type of the object to be processed, the ammonia gas analyzer, and the temperature sensor. A correlation determined in advance, which depends on the temperature in the furnace, between each detected value and the ammonia gas partial pressure in the furnace and the nitrogen concentration of a specific article to be processed disposed in the furnace, Treated based on the nitriding properties of specific treated products Calculate the nitriding (nitriding) ability (nitriding potential) of the atmosphere based on the steel material correction coefficient of the workpiece to be quantified for each type, and the calculated value and the target value of the nitrogen concentration of the workpiece And controlling the flow rate control valve so that the nitrogen concentration of the product to be processed becomes the target value ,
The previously determined correlation is
Nitriding potential (%)
= A (T) x In ( PNH3 ) + b (T)
In: Natural logarithm
P NH3 : Ammonia gas partial pressure
a (T), b (T): Variables depending on the nitriding temperature T
In is the one represented (claim 6).

前記装置によれば、被処理品の種類の如何にかかわらず、同一の方式で常に所望の品質の処理品を得ることができる。   According to the apparatus, a processed product having a desired quality can always be obtained by the same method regardless of the type of the processed product.

他の実施の形態に係る浸窒処理装置は、前記制御装置は、前記被処理品の種類についての情報と、浸窒処理時間についての情報と、前記アンモニアガス分析計及び前記温度センサの各検出値と、前記炉内のアンモニアガス分圧と前記炉内に配置した特定の被処理品の窒素濃度との間の、前記炉内の温度に依存する、予め求めた相関関係と、前記特定の被処理品の浸窒性を基準として被処理品の種類毎に数値化した被処理品の鋼材補正係数と、浸窒処理時間の関数として示される時間補正係数と、に基づいて、雰囲気が有する浸窒(窒化)能力(窒化ポテンシャル)を演算し、前記演算値と被処理品の最終窒素濃度の目標値とを比較して、被処理品の窒素濃度が前記目標値となるように前記流量制御弁を制御し、
前記予め求めた相関関係が、
窒化ポテンシャル(%)
=a(T)×In(P NH3 )+b(T)
In:自然対数
NH3 :アンモニアガス分圧
a(T),b(T):浸窒温度Tに依存する変数
で表されるものとされている(請求項)。
In the nitriding apparatus according to another embodiment, the control device detects information on the type of the article to be processed, information on the nitriding time, and each detection of the ammonia gas analyzer and the temperature sensor. A predetermined correlation between the value and the ammonia gas partial pressure in the furnace and the nitrogen concentration of a specific article to be processed arranged in the furnace, depending on the temperature in the furnace, and the specific The atmosphere has based on the steel correction factor of the product to be processed, which is quantified for each type of product to be processed based on the nitriding property of the product to be processed, and the time correction factor indicated as a function of the nitriding time. Nitrogen (nitriding) capability (nitriding potential) is calculated, the calculated value is compared with the target value of the final nitrogen concentration of the processed product, and the flow rate is set so that the nitrogen concentration of the processed product becomes the target value. Control the control valve ,
The previously determined correlation is
Nitriding potential (%)
= A (T) x In ( PNH3 ) + b (T)
In: Natural logarithm
P NH3 : Ammonia gas partial pressure
a (T), b (T): Variables depending on the nitriding temperature T
In is the one represented (claim 7).

前記装置によれば、浸窒処理時間も加味して被処理品の最終窒素濃度が演算されるので、例えば、浸窒処理時間が、被処理品の窒素濃度を十分高め得るだけ長くない場合でも、それを補償し得るだけアンモニアガスの供給量が多量となるように制御されて、常に目標窒素濃度を備えた処理品を得ることができる。   According to the apparatus, since the final nitrogen concentration of the article to be processed is calculated in consideration of the nitriding treatment time, for example, even when the nitriding treatment time is not long enough to sufficiently increase the nitrogen concentration of the article to be treated. The amount of ammonia gas supplied is controlled to be large enough to compensate for this, and a treated product always having a target nitrogen concentration can be obtained.

好適な実施の一形態として、前記鋼材補正係数が、複数の被処理品について実データを利用して求めた鋼材補正係数と、前記複数の被処理品の化学成分と、の間に認められる相関関係に基づき、前記複数の被処理品とは別種の被処理品について、該別種の被処理品の化学成分に対応する数値として設定されるものとすることもできる(請求項)。 As one preferred embodiment, the steel material correction coefficient is a correlation recognized between a steel material correction coefficient obtained using actual data for a plurality of processed products and chemical components of the plurality of processed products. On the basis of the relationship, for a different type of processed product from the plurality of processed products, it may be set as a numerical value corresponding to the chemical component of the different type of processed product (claim 8 ).

他の実施の一形態として、前記化学成分が、被処理品のクロム含有率であるものとすることもできる(請求項)。 As another embodiment, the chemical component may be the chromium content of the product to be processed (Claim 9 ).

実施の一形態として、前記浸窒処理装置が浸炭をともなう浸炭窒化処理を行うことができる装置であるものとすることもできる(請求項10)。 As an embodiment, the nitriding apparatus may be an apparatus capable of performing a carbonitriding process with carburizing (Claim 10 ).

以下、添付図面を参照して、本発明の実施の一形態について説明する。   Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

浸窒処理品においては、その表面近傍部分、すなわち、処理品の表面から深さ数十μmまでの部分の窒素濃度(表面窒素濃度)が、耐疲労性や耐摩耗性等の機械特性に著しい影響を与える。このため、前記処理品の安定した品質を得るには、浸窒処理方法において、前記表面窒素濃度の十分かつ的確な管理が重要となっている。本発明は、前記表面窒素濃度の十分かつ的確な管理を容易に且つ確実に実施可能とせしめるものであり、特に、前記表面窒素濃度の十分かつ的確な管理を、被処理品の種類(鋼種)や浸窒処理温度、浸窒処理時間の如何にかかわらず、同一の方式で容易に且つ確実に実施可能とせしめるものである。   In nitrogenated products, the nitrogen concentration (surface nitrogen concentration) in the vicinity of the surface, that is, the portion from the surface of the treated product to a depth of several tens of μm (surface nitrogen concentration) is remarkable in mechanical properties such as fatigue resistance and wear resistance. Influence. For this reason, in order to obtain a stable quality of the treated product, it is important to sufficiently and accurately manage the surface nitrogen concentration in the nitriding treatment method. The present invention makes it possible to easily and reliably carry out sufficient and accurate management of the surface nitrogen concentration, and in particular, to manage the surface nitrogen concentration sufficiently and accurately. It is possible to easily and surely implement the same method regardless of the nitriding temperature and the nitriding treatment time.

図1は、本発明の実施の一形態に係る浸窒処理方法を実施するのに用いて好適な、浸窒処理装置のブロック図である。   FIG. 1 is a block diagram of a nitriding treatment apparatus suitable for carrying out a nitriding treatment method according to an embodiment of the present invention.

図1に示すように、前記処理装置1は、装入された被処理品Wに浸窒処理を施すための処理炉2と、該炉2内へのアンモニアガスの供給量を制御する流量制御弁3と、前記炉2内に供給されるアンモニアガスの流量を検出する流量計4と、前記炉2内のアンモニアガス分圧を検出するアンモニアガス分析計5と、前記炉2内の温度を検出する温度センサ6と、前記アンモニアガス分析計5及び前記温度センサ6の各検出値に基づいて、被処理品Wの表面窒素濃度が目標値となるように前記流量制御弁3を制御する制御装置8と、を備えている。なお、図1は、本発明の構成について必要な要素を示したものであり、もちろん実際には、ヒーターや、その他のガスの供給手段等を具備していても良い。   As shown in FIG. 1, the processing apparatus 1 includes a processing furnace 2 for performing a nitriding process on a charged product W, and a flow rate control for controlling the supply amount of ammonia gas into the furnace 2. A valve 3, a flow meter 4 for detecting the flow rate of ammonia gas supplied into the furnace 2, an ammonia gas analyzer 5 for detecting the partial pressure of ammonia gas in the furnace 2, and the temperature in the furnace 2 Control for controlling the flow rate control valve 3 based on the temperature sensor 6 to be detected and the detected values of the ammonia gas analyzer 5 and the temperature sensor 6 so that the surface nitrogen concentration of the workpiece W becomes a target value. And an apparatus 8. Note that FIG. 1 shows elements necessary for the configuration of the present invention. Of course, a heater, other gas supply means, and the like may be provided.

本実施の形態では、前記炉2内のアンモニアガス分圧と、前記炉2内に配置した特定の種類の被処理品wの窒素濃度と、の間の、炉内雰囲気の温度に依存する相関関係を予め求める。併せて、実際の被処理品の浸窒性、すなわち、窒素の浸透し易さの度合いを、実際の被処理品の種類毎に、前記特定の種類の被処理品の浸窒性を基準として関連づける。前記炉2内へのアンモニアガスの供給量は前記流量計4で常時計測され、前記炉2内のアンモニアガス分圧は前記アンモニアガス分析計5で常時計測され、前記炉2内の温度は前記温度センサ6で常時計測される。これらの計測値は全て、前記制御装置8に継続的に出力される。一方、被処理品の種類についての情報と、浸窒処理時間についての情報と、浸窒処理温度と、目標窒素濃度と、は、オペレーターにより前記制御装置8に入力される。そして、前記計測値及びオペレーターによって入力された前記情報とに従い、前記制御装置8において、前記相関関係と、前記被処理品の種類毎の浸窒性の関連づけと、に基づいて、被処理品Wの種類に応じて雰囲気が有する浸窒(窒化)能力(窒化ポテンシャル(NP))が演算される。実際に炉内で浸窒処理されている被処理品は、一定時間処理後に被処理品の窒素濃度が略一定値、すなわち最終表面窒素濃度を示す。前記窒化ポテンシャル(NP)は被処理品を前記最終表面窒素濃度とする、浸窒(窒化)能力を持つ雰囲気の指標であり、前記最終表面窒素濃度と同じ値を示す。前記窒化ポテンシャルの演算値と被処理品の窒素濃度の目標値とが前記制御装置8において比較され、前記流量制御弁3を制御するための制御信号が前記制御装置8で生成される。この制御信号によって前記流量制御弁3が制御され、目標窒素濃度が実現されるように、前記炉2内へのアンモニアガスの供給量が制御される。これにより、被処理品Wの種類の如何にかかわらず、同一の方式で常に所望の品質の処理品を得ることができる。   In the present embodiment, the correlation depending on the temperature of the atmosphere in the furnace between the ammonia gas partial pressure in the furnace 2 and the nitrogen concentration of the specific type of workpiece w placed in the furnace 2 Find the relationship in advance. In addition, the nitridability of the actual product to be processed, that is, the degree of easy penetration of nitrogen, for each type of actual product to be processed is based on the nitridability of the specific type of product to be processed. Associate. The supply amount of ammonia gas into the furnace 2 is constantly measured by the flow meter 4, the ammonia gas partial pressure in the furnace 2 is constantly measured by the ammonia gas analyzer 5, and the temperature in the furnace 2 is The temperature sensor 6 constantly measures. All of these measured values are continuously output to the control device 8. On the other hand, information on the type of product to be processed, information on the nitriding time, nitriding temperature, and target nitrogen concentration are input to the control device 8 by the operator. Then, in accordance with the measured value and the information input by the operator, the control device 8 performs processing based on the correlation and the association of nitriding property for each type of the processing target. The nitriding (nitriding) ability (nitriding potential (NP)) of the atmosphere is calculated according to the type. The article to be treated that is actually subjected to nitriding treatment in the furnace shows a substantially constant value of the nitrogen concentration of the article to be treated after the treatment for a certain time, that is, the final surface nitrogen concentration. The nitriding potential (NP) is an index of an atmosphere having a nitriding (nitriding) ability in which the article to be processed has the final surface nitrogen concentration, and shows the same value as the final surface nitrogen concentration. The calculated value of the nitriding potential and the target value of the nitrogen concentration of the article to be processed are compared in the control device 8, and a control signal for controlling the flow control valve 3 is generated in the control device 8. The flow rate control valve 3 is controlled by this control signal, and the supply amount of ammonia gas into the furnace 2 is controlled so that the target nitrogen concentration is realized. As a result, regardless of the type of product to be processed W, a processed product having a desired quality can always be obtained by the same method.

次に、本発明創案の経緯に沿って、本発明の具体的内容を説明する。   Next, the specific contents of the present invention will be described along the history of the present invention.

浸窒温度域に保持された高温の前記炉2内に、浸窒雰囲気を形成するアンモニアガス(NHガス)が供給(添加)されると、その殆どが水素(H)と窒素(N)とに分解するが、前記炉2内には、次式(1)に示すように、未分解のアンモニアガス(NHガス)が残留する。 When ammonia gas (NH 3 gas) forming a nitriding atmosphere is supplied (added) into the high-temperature furnace 2 maintained in the nitriding temperature range, most of them are hydrogen (H 2 ) and nitrogen (N 2 ), but undecomposed ammonia gas (NH 3 gas) remains in the furnace 2 as shown in the following equation (1).

供給アンモニアガス→H+N+(残留)アンモニアガス ・・・(1)
この式(1)中の前記(残留)アンモニアガスの分圧は、前記アンモニアガス分析計によって計測される。
Supply ammonia gas → H 2 + N 2 + (residual) ammonia gas ... (1)
The partial pressure of the (residual) ammonia gas in the equation (1) is measured by the ammonia gas analyzer.

前記炉2内における前記Nガス[前記式(1)中のN]は、被処理品(鋼材)Wに対する窒化能力を殆ど有しておらず、不活性である。そして、浸炭窒化処理においては、未分解の前記(残留)アンモニアガスが浸窒能力を発揮し、被処理品Wの表面における窒化反応に貢献する。すなわち、前記(残留)アンモニアガスは、被処理品Wの表面で次式(2)のような分解反応を起こすことにより、窒化能を有する活性な窒素<N>を発生させる。そして、この活性窒素<N>が前記被処理品Wの表面から侵入してその内部に拡散することで、窒化(浸窒)が行われる。 The [N 2 in the formula (1)] the N 2 gas in the furnace 2 has no little nitriding capacity for workpieces (steel) W, which is inert. In the carbonitriding process, the undecomposed (residual) ammonia gas exhibits a nitriding ability and contributes to the nitriding reaction on the surface of the workpiece W. That is, the (residual) ammonia gas generates active nitrogen <N> having nitriding ability by causing a decomposition reaction of the following formula (2) on the surface of the workpiece W. Then, this active nitrogen <N> enters from the surface of the article W to be processed and diffuses into the inside thereof, so that nitriding (nitriding) is performed.

(残留)アンモニアガス(NHガス)→<N>+3/2H・・・(2)
前記(残留)アンモニアガスの分圧と前記<N>の量との間には、炉内温度毎に、ある処理時間において、一定の相関関係が成立する。また、前記(残留)アンモニアガスの分圧と前記炉2内へのアンモニアガスの供給量との間にも、炉内温度毎に、一定の相関関係が成立する。したがって、これらの相関関係に基づいて、前記炉2内へのアンモニアガスの供給量を制御することで、前記(残留)アンモニアガスの分圧を制御することができ、これにより、被処理品Wの最終表面窒素濃度を制御することができる。
(Residual) ammonia gas (NH 3 gas) → <N> + 3 / 2H 2 (2)
A certain correlation is established between the partial pressure of the (residual) ammonia gas and the amount <N> for a certain processing time for each furnace temperature. In addition, a certain correlation is established between the partial pressure of the (residual) ammonia gas and the supply amount of the ammonia gas into the furnace 2 for each furnace temperature. Therefore, the partial pressure of the (residual) ammonia gas can be controlled by controlling the supply amount of the ammonia gas into the furnace 2 based on these correlations. The final surface nitrogen concentration can be controlled.

ところで、炉内雰囲気中の(残留)アンモニアガスの分圧と、その雰囲気中で、ある一定時間窒化処理された被処理品の最終表面窒素濃度との間には、被処理品Wの種類毎に、且つ、炉内温度毎に、図2に示すような相関関係がある。相関曲線のカーブの度合いは、被処理品の種類及び炉内温度によって異なる。   By the way, between the partial pressure of the (residual) ammonia gas in the furnace atmosphere and the final surface nitrogen concentration of the article to be treated that has been nitrided in the atmosphere for a certain period of time, each type of article to be treated W In addition, there is a correlation as shown in FIG. 2 for each furnace temperature. The degree of the correlation curve varies depending on the type of product to be processed and the furnace temperature.

図2に示すように、特定の被処理品の最終表面窒素濃度は、炉内(残留)アンモニアガスの分圧の関数であり、且つ、炉内の温度毎に異なる関数である。したがって、被処理品の表面窒素濃度は、温度(浸窒温度)Tに依存する変数を含み、且つ、炉内の(残留)アンモニアガス分圧を変数とする、ある関数によって近似的に表すことができる。基本的に、図2の相関関係を良く近似できる関数ならばその種類は限定されないが、本発明の発明者等は、対数関数による曲線で良く近似できることを見出した。これによれば、被処理品の表面窒素濃度の演算式は、例えば、次式(3)のように設定することができる。 As shown in FIG. 2, the final surface nitrogen concentration of a specific article to be treated is a function of the partial pressure of the ammonia gas (residual) in the furnace and a function that varies depending on the temperature in the furnace. Therefore, the surface nitrogen concentration of the product to be treated should be approximately expressed by a function including a variable depending on the temperature (nitriding temperature) T and the (residual) ammonia gas partial pressure in the furnace as a variable. Can do. Basically, although the type is not limited if good approximation can function the correlation of FIG. 2, the inventors of the present invention have found that it may approximate a curve by logarithmic functions. According to this, the calculation formula of the surface nitrogen concentration of the article to be processed can be set as the following formula (3), for example.

表面窒素濃度(質量パーセント:mass%)
=a(T)×In(PNH3)+b(T) ・・・(3)
In:自然対数
NH3:(残留)アンモニアガス分圧
a(T),b(T):窒化温度Tに依存する変数
(3)式は、残留アンモニアガス分圧の自然対数値を横軸にとり表面窒素濃度を縦軸にとると、それらの間には直線の一次関数の関係があることを示している。そして、前記直線の傾きと切片は炉内温度(窒化温度)Tに依存して定まり、前記直線の傾きを示すのがa(T)、切片を示すのがb(T)である。前記(3)式は、図2に書き込んだ点の数値の組み合わせに基づいて、残留アンモニアガス分圧の自然対数値を横軸にとり表面窒素濃度を縦軸にとったグラフを作成すると、残留アンモニアガス分圧の自然対数値と表面窒素濃度との組み合わせの点が、各窒化温度毎にほぼ一直線上に並ぶことから導かれる。前記式(3)中の(残留)アンモニアガス分圧PNH3は、前記アンモニアガス分析計5で常時計測され、窒化温度Tは、前記温度センサ6で常時計測され、これらの計測値は、前記制御装置8に入力される。前記式(3)に基づき、前記制御装置8において、そのときの浸窒(窒化)雰囲気が有する浸窒(窒化)能力(窒化ポテンシャル(NP))が演算される。そして、前記制御装置8において、その演算値[被処理品Wの最終表面窒素濃度として表せる浸窒(窒化)能力(窒化ポテンシャル(NP))]と目標表面窒素濃度とが比較され、該目標表面窒素濃度が達成されるように、前記流量制御弁3への制御信号が発せられ、雰囲気中へのアンモニアガスの供給量が適切に制御される。
Surface nitrogen concentration (mass percent: mass%)
= A (T) × In (P NH3 ) + b (T) (3)
In: Natural logarithm
P NH3 : (residual) ammonia gas partial pressure
a (T), b (T): Variables depending on the nitriding temperature T
Equation (3) indicates that there is a linear function relationship between the natural logarithm of residual ammonia gas partial pressure on the horizontal axis and the surface nitrogen concentration on the vertical axis. The slope and intercept of the straight line are determined depending on the furnace temperature (nitriding temperature) T, and the slope of the straight line is a (T) and the intercept is b (T). Based on the combination of the numerical values of the points written in FIG. 2, the above equation (3) can be obtained by creating a graph with the natural logarithm of the residual ammonia gas partial pressure on the horizontal axis and the surface nitrogen concentration on the vertical axis. The point of the combination of the natural logarithm of the gas partial pressure and the surface nitrogen concentration is derived from being arranged in a substantially straight line at each nitriding temperature. The (residual) ammonia gas partial pressure P NH3 in the equation (3) is constantly measured by the ammonia gas analyzer 5, and the nitriding temperature T is constantly measured by the temperature sensor 6, and these measured values are Input to the control device 8. Based on the equation (3), the control device 8 calculates the nitriding (nitriding) capability (nitriding potential (NP)) of the nitriding (nitriding) atmosphere at that time. Then, the control device 8 compares the calculated value [nitrogenation (nitriding) ability (nitriding potential (NP)) expressed as the final surface nitrogen concentration of the article W to be processed] with the target surface nitrogen concentration, and the target surface A control signal is issued to the flow control valve 3 so that the nitrogen concentration is achieved, and the supply amount of ammonia gas into the atmosphere is appropriately controlled.

ところで、実際の浸窒処理作業においては、被処理品として、部品やその用途に応じた様々な鋼材の種類が選択される。そして、被処理品は、その種類に応じた浸窒性(浸窒の起こり易さ又は進み易さの度合い)を有する。これは、被処理品の組成、すなわち、鋼に添加された合金元素の種類及びその割合等が異なれば、被処理品への窒素の浸入拡散の挙動が異なるからであると考えられる。よって、すべての種類の鋼材について、前記式(3)を具体化した単一の数値式を適用したのでは、被処理品の表面窒素濃度を十分に管理することは不可能である。この場合、前記式(3)を被処理品の種類毎に具体化し、被処理品の種類毎に異なる演算式を用いることも考えられる。   By the way, in an actual nitriding operation, various types of steel materials are selected as the object to be processed in accordance with the component and its application. And the to-be-processed goods have the nitriding property (degree of the ease of occurrence of nitriding or the ease of advancement) according to the kind. This is considered to be because if the composition of the article to be treated, that is, the type and ratio of the alloying element added to the steel, the behavior of nitrogen infiltration and diffusion into the article to be treated is different. Therefore, if a single numerical formula that embodies the formula (3) is applied to all types of steel materials, it is impossible to sufficiently manage the surface nitrogen concentration of the article to be processed. In this case, it is also conceivable to formulate the expression (3) for each type of product to be processed and use different arithmetic expressions for each type of product to be processed.

しかしながら、この方法によると、被処理品の種類毎に別々の方式で制御を行うことになるので、制御が煩雑となり好ましくない。   However, according to this method, control is performed by a different method for each type of article to be processed, which is not preferable because the control becomes complicated.

そこで、本発明の発明者等は、処理品の品質の管理をよりシンプルなプロセスで行えること、すなわち、被処理品の種類が異なっても常に同一の方式で制御できること、を目的として、前記式(3)を基準とし、その基準式に鋼材の種類に応じた浸窒性を適宜に反映させて適用することに想到した。   Therefore, the inventors of the present invention are able to manage the quality of processed products by a simpler process, that is, the above-mentioned formula can be always controlled by the same method even if the types of processed products are different. Based on (3) as a standard, the present inventors have conceived that the standard formula is appropriately reflected by applying the nitriding property corresponding to the type of steel material.

前記目的を達成するため、本発明では、各種の被処理品の浸窒性を、被処理品の種類毎に、特定の被処理品の浸窒性を基準として関連付けする。そして、この浸窒性の関連付けを用いて前記式(3)の計算結果を補正し、浸窒性の違いを加味して表面窒素濃度を演算できるようにする。   In order to achieve the object, in the present invention, the nitriding properties of various products to be processed are associated with the nitriding properties of specific products to be processed for each type of products to be processed. And the calculation result of said Formula (3) is correct | amended using this nitrousability correlation, and the surface nitrogen density | concentration can be calculated in consideration of the difference in nitrousability.

具体的には、浸窒雰囲気中で浸窒処理された特定の種類の被処理品(限定はされないが、例えば、SCr420材)の最終表面窒素濃度と同じ値を示す、前記特定の種類の被処理品に対して前記雰囲気が有する浸窒(窒化)能力を表す指標を窒化ポテンシャル(NP)と呼ぶことにする。この場合、前記式(3)は、次の通りとなる。   Specifically, the specific type of object to be treated that exhibits the same value as the final surface nitrogen concentration of a specific type of object to be treated (for example, but not limited to, SCr420 material) that has been subjected to nitriding treatment in a nitriding atmosphere. An index representing the nitriding (nitriding) ability of the atmosphere with respect to the processed product is referred to as nitriding potential (NP). In this case, the formula (3) is as follows.

窒化ポテンシャル(NP)(%)
=a(T)×In(PNH3)+b(T) ・・・(3´)
In:自然対数
NH3:(残留)アンモニアガス分圧
a(T),b(T):窒化温度Tに依存する変数
前記式(3´)によって演算された窒化ポテンシャルNPは、特定の被処理品としてのSCr420材の最終表面窒素濃度の、計測された実際値と一致している。よって、縦軸を最終表面窒素濃度の実際値、横軸を窒化ポテンシャル(NP)として、縦軸、横軸の目盛りを同一にしてグラフ化すると、例えば図3に示すように、右上がりの直線となる。
Nitriding potential (NP) (%)
= A (T) × In (P NH3 ) + b (T) (3 ′)
In: Natural logarithm
P NH3 : (residual) ammonia gas partial pressure a (T), b (T): Variable depending on the nitriding temperature T The nitriding potential NP calculated by the above equation (3 ′) is an SCr420 as a specific article to be processed. This is consistent with the measured actual value of the final surface nitrogen concentration of the material. Therefore, if the vertical axis is the actual value of the final surface nitrogen concentration, the horizontal axis is the nitriding potential (NP), and the vertical and horizontal scales are the same, for example, as shown in FIG. It becomes.

次に、図2に示す相関関係を、被処理品の種類毎に実データで明らかにし、その実データのグラフを、図3と同様に、横軸を前記(3´)に基づく窒化ポテンシャル(NP)としてグラフ化した(具体例は、実施例として後述する)。その結果、各被処理品についての図3の相関関係のグラフは、前記SCr420材についての図3の直線と傾きが違うだけであることを見出した。この場合、各被処理品についての図3の直線を、前記SCr420材についての図3の直線に一致させるための係数が、被処理品の種類毎の前記浸窒性関連付けに相当する。前記係数を鋼材補正係数αと呼ぶとすれば、被処理品の最終表面窒素濃度は窒化ポテンシャル(NP)なので、統一的に次式(4)で表すことができる。   Next, the correlation shown in FIG. 2 is clarified by actual data for each type of product to be processed, and the graph of the actual data is shown in FIG. 3, and the horizontal axis indicates the nitriding potential (NP) based on (3 ′). ) (A specific example will be described later as an example). As a result, it has been found that the correlation graph of FIG. 3 for each processed product is only different in inclination from the straight line of FIG. 3 for the SCr420 material. In this case, the coefficient for matching the straight line of FIG. 3 for each processed product with the straight line of FIG. 3 for the SCr420 material corresponds to the nitriding association for each type of processed product. If the coefficient is referred to as a steel material correction coefficient α, the final surface nitrogen concentration of the product to be processed is the nitriding potential (NP), and therefore can be uniformly expressed by the following equation (4).

窒化ポテンシャル(NP)(被処理品の種類を加味した一般演算式)
=α{a(T)×In(PNH3)+b(T)} ・・・(4)
α:鋼材補正係数(被処理品毎に予め設定される)
前記式(4)を利用して算出された窒化ポテンシャル(演算値)は、被処理品がどのような種類であっても、各被処理品の最終表面窒素濃度の実際値をよく表すことになる。
Nitriding potential (NP) (general calculation formula considering the type of product to be treated)
= Α {a (T) × In (P NH3 ) + b (T)} (4)
α: Steel correction factor (preset for each product to be processed)
The nitriding potential (calculated value) calculated using the equation (4) well represents the actual value of the final surface nitrogen concentration of each processed product regardless of the type of processed product. Become.

実際の浸窒処理に当たっては、被処理品の種類がオペレーターによって前記制御装置8に入力され、その入力に従って、前記制御装置8で予め設定されている補正係数群の中から具体的な鋼材補正係数が自動的に選択され、それに基づいて、そのときの浸窒(窒化)雰囲気が有する窒化ポテンシャル(NP)の現在値が、被処理品の種類を加味して、演算されることになる。よって、窒化ポテンシャル演算式を被処理品の種類毎に予め計測や設定しておく必要がなく、被処理品の種類が異なっても同一の方式でシンプルにできる利点がある。   In the actual nitriding process, the type of product to be processed is input to the control device 8 by an operator, and a specific steel material correction coefficient is selected from a correction coefficient group set in advance by the control device 8 according to the input. Is automatically selected, and based on this, the current value of the nitriding potential (NP) of the nitriding (nitriding) atmosphere at that time is calculated in consideration of the type of product to be processed. Therefore, it is not necessary to previously measure and set the nitriding potential calculation formula for each type of product to be processed, and there is an advantage that it can be simplified by the same method even if the type of product to be processed is different.

ここで、被処理品として適当なものは、浸炭処理の対象となる「浸炭用炭素鋼;はだ焼鋼」が好ましい。例えば炭素鋼、クロム鋼(SCr)、クロムモリブデン鋼(SCM)、ニッケルクロム鋼(SNC)、ニッケルクロムモリブデン鋼(SNCM)等の浸炭用鋼がある。   Here, a suitable product to be treated is preferably “carbon steel for carburizing; For example, there are carburizing steels such as carbon steel, chromium steel (SCr), chromium molybdenum steel (SCM), nickel chromium steel (SNC), and nickel chromium molybdenum steel (SNCM).

また、被処理品の表面窒素濃度とは、概ね表面から深さ50μm以内の濃度を指し、例えば試験片を切断および研磨後、EPMAを用いて試験片の表面から深さ方向の窒素の濃度プロファイルの測定をし、表面から20μmの深さの部分の窒素濃度を扱えば良い。   Further, the surface nitrogen concentration of the article to be treated generally means a concentration within a depth of 50 μm from the surface. For example, after cutting and polishing the test piece, the concentration profile of nitrogen in the depth direction from the surface of the test piece using EPMA And measuring the nitrogen concentration at a depth of 20 μm from the surface.

次に、浸窒処理時間の影響による補正係数について説明する。   Next, the correction coefficient due to the influence of the nitriding time will be described.

ある一定の炉内雰囲気中に配置された被処理品の表面窒素濃度は、窒化時間の経過とともに図4のように増加し、一定の時間で略一定の最終表面窒素濃度となる。したがって、被処理品の表面窒素濃度が十分に上昇するのに必要な処理時間より短い窒化処理では、前記一般演算式で求めた窒化ポテンシャル(NP)が個々の被処理品の実際の表面窒素濃度よりも高い値となり、目標とする処理品の表面窒素濃度を適切に得る為の数値にならなくなってしまう。この場合、被処理品の表面窒素濃度は、窒化処理開始後のある窒化時間内においては、窒化時間tの関数であると考えることができる。そこで、表面窒素濃度の前記一般演算式は、窒化時間を加味して次のように補正することができる。   The surface nitrogen concentration of the article to be processed placed in a certain furnace atmosphere increases as the nitriding time elapses as shown in FIG. 4, and becomes a substantially constant final surface nitrogen concentration in a certain time. Therefore, in nitriding that is shorter than the processing time required for sufficiently increasing the surface nitrogen concentration of the article to be treated, the nitriding potential (NP) obtained by the above general formula is the actual surface nitrogen concentration of each article to be treated. It becomes a value higher than that, and it will not become a numerical value for properly obtaining the surface nitrogen concentration of the target processed product. In this case, the surface nitrogen concentration of the article to be processed can be considered as a function of the nitriding time t within a certain nitriding time after the start of the nitriding treatment. Therefore, the general arithmetic expression for the surface nitrogen concentration can be corrected as follows by taking the nitriding time into account.

窒化ポテンシャル(NP)(式(4)に処理時間を加味した一般演算式)
=前記式(4)×β(t)
=α・β(t){a(T)×In(PNH3)+b(T)} ・・・(5)
α:鋼材補正係数(被処理品毎に予め設定される)
β(t):窒化処理時間tの関数として表される補正係数(時間補正係数)
前記式(5)において、βは窒化処理時間tの関数であり(図5参照)、被処理品の表面窒素濃度が前記一般演算式(4)による演算値まで十分に上昇し、それ以上処理を続けても殆ど上昇しなくなる時間では、β(t)=1になるとみなす。
Nitriding potential (NP) (general calculation formula that takes processing time into consideration in formula (4))
= Formula (4) × β (t)
= Α · β (t) {a (T) × In (P NH3 ) + b (T)} (5)
α: Steel correction factor (preset for each product to be processed)
β (t): correction coefficient expressed as a function of nitriding time t (time correction coefficient)
In the equation (5), β is a function of the nitriding time t (see FIG. 5), and the surface nitrogen concentration of the article to be treated is sufficiently increased to the value calculated by the general equation (4), so that the further processing It is assumed that β (t) = 1 in the time when the increase hardly occurs even if the operation is continued.

前記時間補正係数β(t)は、被処理品の表面窒素濃度の、時間に対する上昇率(図4参照)を良く近似できる関数ならばその種類は限定されないが、例えば、対数関数で良く近似できるとすれば、具体的に次のように表すことができる。   The time correction coefficient β (t) is not limited as long as it is a function that can closely approximate the rate of increase of the surface nitrogen concentration of the object to be processed with respect to time (see FIG. 4). For example, it can be approximated well by a logarithmic function. Then, it can be expressed specifically as follows.

β(t)=c×In(t+d)+e
t:浸窒処理時間(分)
c,d,e:定数
前記式(5)を用いれば、窒化雰囲気中にある被処理品の表面窒素濃度を、様々な種類の被処理品について処理時間も織りこんだ形で、統一的且つ的確に演算することができる。また、短時間処理の場合には、長時間処理の場合よりも雰囲気中の(残留)アンモニアガス分圧が多くなるようにアンモニアガスの供給量が自動制御されることになるので、狙いとする品質(表面窒素濃度)を短時間でも安定的且つ容易に得ることが可能となり、処理時間(リードタイム)が短縮される効果がある。なお、窒化処理時間は、オペレーターによって処理毎に前記制御装置8に入力される。
β (t) = c × In (t + d) + e
t: Nitrogen treatment time (min)
c, d, e: constants Using the above formula (5), the surface nitrogen concentration of the article to be treated in the nitriding atmosphere is unified and in a form that incorporates the treatment time for various kinds of articles to be treated. It can be calculated accurately. In addition, in the case of short-time treatment, the supply amount of ammonia gas is automatically controlled so that the (residual) ammonia gas partial pressure in the atmosphere is larger than in the case of long-time treatment, so it is aimed. Quality (surface nitrogen concentration) can be obtained stably and easily even in a short time, and the processing time (lead time) can be shortened. The nitriding time is input to the control device 8 by the operator for each process.

なお、本願の処理方法はいわゆる浸炭窒化処理及びその装置にも同様に適用できる。   In addition, the processing method of the present application can be similarly applied to a so-called carbonitriding process and its apparatus.

一実施例として、前記鋼材補正係数αは、具体的に次のようにして求めることができる。   As an example, the steel material correction coefficient α can be specifically obtained as follows.

図6は、炉内(残留)アンモニアガス分圧と、その雰囲気中における各種の被処理品(鋼材)A〜F及び基準となる特定の被処理品としてのSCr420材の表面窒素濃度の実際値と、の組み合わせを、実データに基づいてプロットしたグラフである。ここで、被処理品(鋼材)A〜Fは、次の表1に示すような化学成分を有する鋼材である。また、図6の元となった実データは、処理温度が異なるものを含んでいるが、時間補正が必要なものは含んでいない。

Figure 0005167553
FIG. 6 shows the actual values of the partial pressure of ammonia gas in the furnace (remaining), the surface nitrogen concentration of the various processed products (steel materials) A to F in the atmosphere, and the SCr420 material as a specific specified processed product. It is the graph which plotted the combination of and based on real data. Here, the articles to be processed (steel materials) A to F are steel materials having chemical components as shown in Table 1 below. In addition, the actual data that is the basis of FIG. 6 includes data with different processing temperatures, but does not include data that requires time correction.
Figure 0005167553

次に、図6の各相関関係を、基準とした特定の被処理品(本実施例の場合はSCr420材)についての式(3´)(図2に相当)の相関関係を求め、その後に前記式(3´)と一致させるため係数を、被処理品の種類毎に探し出す。この係数が鋼材補正係数αであり、被処理品の浸窒性を、被処理品の種類毎に、前記SCr420材の浸窒性を基準として関連付けしたものに相当する。   Next, the correlation of the equation (3 ′) (corresponding to FIG. 2) for a specific product to be processed (in the case of the present embodiment, the SCr420 material) based on each correlation in FIG. 6 is obtained, and thereafter Coefficients are searched for each type of product to be processed in order to match the above equation (3 ′). This coefficient is the steel material correction coefficient α, which corresponds to the relationship between the nitriding properties of the products to be processed and the nitriding properties of the SCr420 material for each type of the processed products.

前記式(3´)を用いて、図6の元となった実データから、表面窒素濃度の実際値(縦軸)と、窒化ポテンシャル(NP)(最終表面窒素濃度で表される雰囲気が有する浸窒能力演算値)と、の組み合わせをプロットしたグラフに書き換えると、図7のようになる。図7より、SCr420材の各点は、右上がりの直線上に分布していることが分かる。プロットされた各点と、基準となるSCr420材の右上がりの直線と、の間のずれを埋めるための係数が、前記鋼材補正係数となる。この場合、基準となるSCr420材についての鋼材補正係数を1とすれば、図7の読み取りにより、A〜Fの各被処理品についての鋼材補正係数αは、次のように設定できることになる。   Using the above formula (3 ′), the actual data (vertical axis) of the surface nitrogen concentration and the nitriding potential (NP) (atmosphere represented by the final surface nitrogen concentration have FIG. 7 shows a graph in which the combination of the nitriding ability calculation value) is plotted. From FIG. 7, it can be seen that the points of the SCr420 material are distributed on a straight line rising to the right. A coefficient for filling a gap between each plotted point and the straight line that rises to the right of the reference SCr420 material is the steel material correction coefficient. In this case, if the steel correction coefficient for the reference SCr420 material is 1, the steel correction coefficient α for each of the processed products A to F can be set as follows from the reading of FIG.

被処理品(鋼材)Aの鋼材補正係数:約1.00
被処理品(鋼材)Bの鋼材補正係数:約1.00
被処理品(鋼材)Cの鋼材補正係数:約1.00
被処理品(鋼材)Dの鋼材補正係数:約0.7
被処理品(鋼材)Eの鋼材補正係数:約0.63
被処理品(鋼材)Fの鋼材補正係数:約0.73
図7について前記各鋼材補正係数を加味すると、図8のように、基準となるSCr420材の分布と同じ態様の分布となる。
Steel material correction factor of processed product (steel material) A: about 1.00
Steel material correction factor of workpiece (steel material) B: about 1.00
Steel material correction coefficient of processed product (steel material) C: about 1.00
Steel material correction factor of workpiece (steel material) D: about 0.7
Steel material correction factor of processed product (steel material) E: Approximately 0.63
Steel material correction factor of processed product (steel material) F: about 0.73
When each steel material correction coefficient is added to FIG. 7, the distribution in the same mode as the distribution of the reference SCr420 material is obtained as shown in FIG.

図9は、図6と同様に、炉内残留アンモニアガス分圧と、その雰囲気中における前記被処理品(鋼材)A〜F及び基準となるSCr420材の表面窒素濃度の実際値と、の組み合わせを、実データに基づいてプロットしたグラフである。但し、図6とは異なり、図9には、時間補正が必要となるデータも含まれている。   FIG. 9 shows a combination of the residual ammonia gas partial pressure in the furnace and the actual value of the surface nitrogen concentration of the article to be processed (steel materials) A to F and the reference SCr420 material as in FIG. Is a graph plotted based on actual data. However, unlike FIG. 6, FIG. 9 also includes data that requires time correction.

図9を図7と同様のグラフに変換したものが図10、図10に前記被処理品(鋼材)A〜Fの鋼材補正係数を加味した結果が図11、図11に前記時間補正係数β(t)を加味した結果が図12である。このように、前記鋼材補正と前記時間補正とを行うことで、基準とした前記SCr420材と同様に、処理雰囲気の窒化ポテンシャルの演算値を被処理品の最終表面窒素濃度の実際値に一致させることができ、これにより、被処理品の品質の管理を常に正確に行うことができる。   FIG. 9 is a graph obtained by converting FIG. 9 into the same graph as FIG. 7, and FIG. 10 shows the result of adding the steel material correction coefficient of the products (steel materials) A to F to FIG. FIG. 12 shows the result of adding (t). Thus, by performing the steel material correction and the time correction, the calculated value of the nitriding potential of the processing atmosphere is made to coincide with the actual value of the final surface nitrogen concentration of the object to be processed, similarly to the reference SCr420 material. As a result, the quality of the processed product can always be managed accurately.

なお、前記鋼材補正係数の設定に当たっては、前記のように多くの実データを収集することが必須という訳ではない。すなわち、データのない他の被処理品については、それを実験的にある窒化ポテンシャルにて処理し、その結果得られた実際の表面窒素濃度を前記窒化ポテンシャルと比較することで、補正係数を決定することができる。すなわち、最小で一回だけ実際に浸窒処理を行えば、その種類の被処理品について、鋼材補正係数αを決定することができる。例えば、特定鋼種(SCr420)における窒化ポテンシャル0.5mass%の設定にて、ある被処理品Xを浸窒処理したとき、その最終表面窒素濃度の実際値が0.2mass%であったとすれば、0.2=αx×0.5であるから、前記被処理品Xの鋼材補正係数αxは、0.2÷0.5=0.4となる。   In setting the steel material correction coefficient, it is not essential to collect a lot of actual data as described above. That is, for other workpieces for which there is no data, the correction coefficient is determined by processing it at a certain nitriding potential and comparing the actual surface nitrogen concentration obtained as a result with the nitriding potential. can do. That is, if the nitriding treatment is actually performed at least once, the steel material correction coefficient α can be determined for that kind of product. For example, assuming that the actual value of the final surface nitrogen concentration was 0.2 mass% when a certain product X was subjected to nitriding treatment at a nitriding potential of 0.5 mass% in a specific steel type (SCr420), Since 0.2 = αx × 0.5, the steel material correction coefficient αx of the workpiece X is 0.2 ÷ 0.5 = 0.4.

また、鋼材補正係数αは、次の方法によっても求めることができる。   In addition, the steel material correction coefficient α can be obtained by the following method.

本発明の発明者等は、実データから求めた複数の前記被処理品(鋼材)A〜Fの鋼材補正係数と、前記被処理品A〜Fの化学成分との間に、所定の相関関係があることを見出した。具体的には、被処理品の化学成分(被処理品A〜Fの化学成分は、表1参照)の内、クロム含有率(Cr量:mass%)と前記被処理品(鋼材)A〜Fの鋼材補正係数との間に、図13の相関関係があることが分かった。よってこの相関関係を利用すれば、他の種類の鋼材についてもCr量(クロム含有率)さえ把握できれば、実データなしでも鋼材補正係数αを決定することができる。   The inventors of the present invention have a predetermined correlation between the steel material correction coefficients of the plurality of products (steel materials) A to F obtained from actual data and the chemical components of the products A to F. Found that there is. Specifically, among the chemical components of the product to be processed (see Table 1 for the chemical components of the products to be processed A to F), the chromium content (Cr amount: mass%) and the product to be processed (steel material) A to It was found that there is a correlation shown in FIG. 13 with the steel material correction coefficient of F. Therefore, if this correlation is used, the steel material correction coefficient α can be determined without actual data as long as the Cr amount (chromium content) can be grasped for other types of steel materials.

この方法による場合には、前記相関関係を予め図1の前記制御装置8にインプットしておく。一方、被処理品の化学成分(具体的にはCr量)についての情報は、被処理品の種類についての情報として、オペレーターが前記制御装置8に入力する。そして、前記制御装置8において、前記相関関係と、入力された化学成分とから、鋼材補正係数が自動的に演算され、この演算値がアンモニアガス供給量の制御に利用されることになる。   In the case of this method, the correlation is input to the control device 8 in FIG. 1 in advance. On the other hand, information on the chemical component (specifically, Cr content) of the product to be processed is input to the control device 8 by the operator as information on the type of product to be processed. And in the said control apparatus 8, a steel material correction coefficient is automatically calculated from the said correlation and the input chemical component, and this calculated value is utilized for control of ammonia gas supply amount.

なお、Cr以外の化学成分でも、その化学成分と、複数の被処理品について実データを利用して求めた鋼材補正係数との間に一定の相関関係が認められれば、鋼材補正係数を設定するための要素として利用可能である。例えば、Al(アルミニウム)やV(バナジウム)やTi(チタン)等、窒素と化合物を形成し易い元素の含有比率は、鋼材補正係数設定のための要素としての利用可能性が高い。   Even in the case of chemical components other than Cr, if a certain correlation is found between the chemical components and the steel material correction coefficient obtained using actual data for a plurality of processed products, the steel material correction coefficient is set. It can be used as an element for For example, the content ratio of elements that easily form a compound with nitrogen, such as Al (aluminum), V (vanadium), and Ti (titanium), is highly available as an element for setting a steel material correction coefficient.

また、複数の化学成分が鋼材補正係数設定のための要素となることも考えられ、この場合には、複数の元素の成分量のバランスから求められる複合的な相関に基づいて、鋼材補正係数を設定することになる。   It is also conceivable that multiple chemical components become elements for setting the steel material correction coefficient.In this case, the steel material correction coefficient is calculated based on the complex correlation obtained from the balance of the component amounts of the multiple elements. Will be set.

本発明の実施の一形態に係るガス浸炭窒化処理方法を実施するのに用いて好適な、ガス浸炭窒化処理装置のブロック図である。1 is a block diagram of a gas carbonitriding apparatus suitable for implementing a gas carbonitriding method according to an embodiment of the present invention. FIG. 窒化雰囲気中の残留アンモニアガスの量と、その雰囲気中に配置された処理品の表面窒素濃度と、の間の相関関係を示すグラフである。It is a graph which shows the correlation between the quantity of residual ammonia gas in nitriding atmosphere, and the surface nitrogen concentration of the processed goods arrange | positioned in the atmosphere. 図2の元データと、式(3´)とを用いて、特定の被処理品(SCr420材)について、表面窒素濃度の実際値(縦軸)と窒化ポテンシャル(横軸)との関係を示したグラフである。The relationship between the actual value of surface nitrogen concentration (vertical axis) and the nitriding potential (horizontal axis) is shown for a specific product (SCr420 material) using the original data in FIG. 2 and the formula (3 ′). It is a graph. 窒化処理時間と、処理品の表面窒素濃度と、の間の一般的な相関関係を示すグラフである。It is a graph which shows the general correlation between nitriding time and the surface nitrogen concentration of a processed article. 窒化処理時間と、時間補正係数と、の間の一般的な相関関係を示すグラフである。It is a graph which shows the general correlation between nitriding processing time and a time correction coefficient. 炉内残留アンモニアガス量と、その雰囲気中における処理品の表面窒素濃度と、の間の相関関係を、実データ(時間補正が必要なものを含まない)に基づいて、被処理品(鋼材)A〜F及びSCr420の種類別にプロットしたグラフである。The correlation between the amount of residual ammonia gas in the furnace and the surface nitrogen concentration of the treated product in the atmosphere, based on actual data (not including those that require time correction) to be treated (steel) It is the graph plotted according to the kind of AF and SCr420. 図6の元データと、式(3´)とを用いて、被処理品A〜F及びSCr420について、表面窒素濃度の実際値と窒素ポテンシャル(横軸)との関係をプロットしたグラフである。It is the graph which plotted the relationship between the actual value of a surface nitrogen concentration, and nitrogen potential (horizontal axis) about to-be-processed articles A-F and SCr420 using the original data of FIG. 6, and Formula (3 '). 図7に鋼材補正を行った結果を示すグラフである。FIG. 7 is a graph showing a result of steel material correction. 炉内残留アンモニアガス量と、その雰囲気中における処理品の表面窒素濃度と、の間の相関関係を、実データ(時間補正が必要なものも含む)に基づいて、被処理品(鋼材)A〜F及びSCr420の種類別にプロットしたグラフである。The correlation between the amount of residual ammonia gas in the furnace and the surface nitrogen concentration of the treated product in the atmosphere is based on actual data (including those requiring time correction) to be treated (steel) A It is the graph plotted according to the kind of -F and SCr420. 図9の元データと、式(3´)とを用いて、被処理品A〜F及びSCr420について、表面窒素濃度の実際値と窒素ポテンシャル(横軸)との関係をプロットしたグラフである。It is the graph which plotted the relationship between the actual value of a surface nitrogen concentration, and nitrogen potential (horizontal axis) about to-be-processed articles A-F and SCr420 using the original data of FIG. 9, and Formula (3 '). 図10に鋼材補正を行った結果を示すグラフである。FIG. 10 is a graph showing the result of steel material correction. 図11に時間補正を行った結果を示すグラフである。FIG. 11 is a graph showing the result of time correction. 被処理品(鋼材)A〜F中のCr量(クロム量:mass%)と、被処理品A〜Fの鋼材補正係数との間の相関関係を示すグラフである。It is a graph which shows the correlation between the Cr amount (chromium amount: mass%) in to-be-processed goods (steel materials) AF, and the steel material correction coefficient of to-be-processed goods AF.

符号の説明Explanation of symbols

1 処理装置
2 処理炉
3 流量制御弁
4 流量計
5 アンモニアガス分析計
6 温度センサ
7 処理時間計
8 制御装置
W 被処理品
DESCRIPTION OF SYMBOLS 1 Processing apparatus 2 Processing furnace 3 Flow control valve 4 Flowmeter 5 Ammonia gas analyzer 6 Temperature sensor 7 Processing time meter 8 Control apparatus W To-be-processed goods

Claims (10)

(1)浸窒雰囲気中のアンモニアガス分圧と、前記雰囲気中に置かれた被処理品の窒素濃度との間の、前記雰囲気の温度に依存する相関関係を求めておき、
(2)実際の浸窒処理における雰囲気中のアンモニアガス分圧と、前記実際の雰囲気の温度と、を計測し、
(3)アンモニアガス分圧の前記計測値と、雰囲気の温度の前記計測値と、前記相関関係と、に基づいて、雰囲気が有する浸窒(窒化)能力(窒化ポテンシャル)を演算し、
(4)前記窒化ポテンシャルの演算値と被処理品の窒素濃度の目標値とを比較して、
(5)被処理品の窒素濃度が前記目標値となるように前記雰囲気中へのアンモニアガスの供給量を制御する浸窒処理方法であって、
前記相関関係が、
窒化ポテンシャル(%)
=a(T)×In(P NH3 )+b(T)
In:自然対数
NH3 :アンモニアガス分圧
a(T),b(T):浸窒温度Tに依存する変数
で表される、浸窒処理方法。
(1) Finding a correlation depending on the temperature of the atmosphere between the partial pressure of ammonia gas in the nitriding atmosphere and the nitrogen concentration of the article to be processed placed in the atmosphere;
(2) Measure the ammonia gas partial pressure in the atmosphere in the actual nitriding treatment and the temperature of the actual atmosphere,
(3) Based on the measured value of the ammonia gas partial pressure, the measured value of the temperature of the atmosphere, and the correlation, the nitriding (nitriding) capability (nitriding potential) of the atmosphere is calculated,
(4) Compare the calculated value of the nitriding potential with the target value of the nitrogen concentration of the article to be processed,
(5) The above immersion that controls the supply amount of the ammonia gas into the atmosphere nitrogen treatment method as the nitrogen concentration of the processed products becomes the target value,
The correlation is
Nitriding potential (%)
= A (T) x In ( PNH3 ) + b (T)
In: Natural logarithm
P NH3 : Ammonia gas partial pressure
a (T), b (T): Variables depending on the nitriding temperature T
Nitrogen treatment method represented by
(イ)浸窒雰囲気中のアンモニアガス分圧と、前記雰囲気中に置かれた特定の被処理品の窒素濃度との間の、前記雰囲気の温度に依存する相関関係を求め、
(ロ)さらに被処理品の浸窒性を、被処理品の種類毎に、特定の被処理品の浸窒性を基準として関連付け、
(ハ)実際の浸窒処理における雰囲気中のアンモニアガス分圧と、前記実際の雰囲気の温度と、を計測し、
(ニ)アンモニアガス分圧の前記計測値と、雰囲気の温度の前記計測値と、前記相関関係と、前記関連付けと、に基づいて、雰囲気が有する浸窒(窒化)能力(窒化ポテンシャル)を演算し、
(ホ)前記窒化ポテンシャルの演算値と被処理品の窒素濃度の目標値とを比較して、
(ヘ)被処理品の窒素濃度が前記目標値となるように前記雰囲気中へのアンモニアガスの供給量を制御する浸窒処理方法であって、
前記相関関係が、
窒化ポテンシャル(%)
=a(T)×In(P NH3 )+b(T)
In:自然対数
NH3 :アンモニアガス分圧
a(T),b(T):浸窒温度Tに依存する変数
で表される、浸窒処理方法。
(A) Obtaining a correlation depending on the temperature of the atmosphere between the partial pressure of ammonia gas in the nitriding atmosphere and the nitrogen concentration of a specific article to be treated placed in the atmosphere;
(B) Further, the nitriding properties of the products to be processed are related to the types of the products to be processed based on the nitriding properties of the specific products to be processed,
(C) Measure the ammonia gas partial pressure in the atmosphere in the actual nitriding treatment and the temperature of the actual atmosphere;
(D) Calculate the nitriding (nitriding) ability (nitriding potential) of the atmosphere based on the measured value of the ammonia gas partial pressure, the measured value of the ambient temperature, the correlation, and the correlation. And
(E) Comparing the calculated value of the nitriding potential with the target value of the nitrogen concentration of the product to be processed,
(F) an the immersion that controls the supply amount of the ammonia gas into the atmosphere nitrogen treatment method as the nitrogen concentration of the processed products becomes the target value,
The correlation is
Nitriding potential (%)
= A (T) x In ( PNH3 ) + b (T)
In: Natural logarithm
P NH3 : Ammonia gas partial pressure
a (T), b (T): Variables depending on the nitriding temperature T
Nitrogen treatment method represented by
前記(3)または(ニ)のプロセスにおいて、浸窒処理時間の関数として示される時間補正を加味し、浸窒処理時間の長短にかかわらず前記(3)または(ニ)の演算値が被処理品の浸窒処理後の窒素濃度を示すようにせしめる、請求項1又は2に記載の浸窒処理方法。   In the process (3) or (d) above, taking into account the time correction indicated as a function of the nitriding time, the calculated value of (3) or (d) is processed regardless of the length of the nitriding time. The nitriding method according to claim 1 or 2, wherein the nitrogen concentration after the nitriding treatment of the product is indicated. 前記浸窒処理が浸炭をともなう浸炭窒化処理であることを特徴とする、請求項1乃至のいずれか一項に記載の浸窒処理方法。 The nitriding treatment method according to any one of claims 1 to 3 , wherein the nitriding treatment is a carbonitriding treatment involving carburizing. 装入された被処理品に浸窒処理を施すための処理炉と、該炉内へのアンモニアガスの供給量を制御する流量制御弁と、前記炉内に供給されるアンモニアガスの流量を検出する流量計と、前記炉内のアンモニアガス分圧を検出するアンモニアガス分析計と、前記炉内の温度を検出する温度センサと、前記流量制御弁を制御する制御装置と、を備えている浸窒処理装置であって、
前記制御装置は、
前記アンモニアガス分析計及び前記温度センサの各検出値と、
前記炉内のアンモニアガス分圧と前記炉内に配置した被処理品の窒素濃度との間の、前記炉内の温度に依存する、予め求めた相関関係と、
に基づいて、雰囲気が有する浸窒(窒化)能力(窒化ポテンシャル)を演算し、
前記演算値と被処理品の窒素濃度の目標値とを比較して、被処理品の窒素濃度が前記目標値となるように前記流量制御弁を制御し、
前記予め求めた相関関係が、
窒化ポテンシャル(%)
=a(T)×In(P NH3 )+b(T)
In:自然対数
NH3 :アンモニアガス分圧
a(T),b(T):浸窒温度Tに依存する変数
で表される、浸窒処理装置。
A processing furnace for performing nitriding treatment on the product to be charged, a flow rate control valve for controlling the supply amount of ammonia gas into the furnace, and a flow rate of ammonia gas supplied into the furnace are detected. An immersion gas analyzer, an ammonia gas analyzer for detecting the partial pressure of ammonia gas in the furnace, a temperature sensor for detecting the temperature in the furnace, and a control device for controlling the flow control valve. A nitrogen treatment device,
The controller is
Each detected value of the ammonia gas analyzer and the temperature sensor,
A correlation determined in advance depending on the temperature in the furnace between the ammonia gas partial pressure in the furnace and the nitrogen concentration of the article to be processed disposed in the furnace;
Based on the above, calculate the nitriding (nitriding) ability (nitriding potential) of the atmosphere,
Comparing the calculated value with the target value of the nitrogen concentration of the product to be processed, and controlling the flow rate control valve so that the nitrogen concentration of the product to be processed becomes the target value ,
The previously determined correlation is
Nitriding potential (%)
= A (T) x In ( PNH3 ) + b (T)
In: Natural logarithm
P NH3 : Ammonia gas partial pressure
a (T), b (T): Variables depending on the nitriding temperature T
Nitrogen treatment equipment represented by
装入された被処理品に浸窒処理を施すための処理炉と、該炉内へのアンモニアガスの供給量を制御する流量制御弁と、前記炉内に供給されるアンモニアガスの流量を検出する流量計と、前記炉内のアンモニアガス分圧を検出するアンモニアガス分析計と、前記炉内の温度を検出する温度センサと、前記流量制御弁を制御する制御装置と、を備えている浸窒処理装置であって、
前記制御装置は、
前記被処理品の種類についての情報と、
前記アンモニアガス分析計及び前記温度センサの各検出値と、
前記炉内のアンモニアガス分圧と前記炉内に配置した特定の被処理品の窒素濃度との間の、前記炉内の温度に依存する、予め求めた相関関係と、
前記特定の被処理品の浸窒性を基準として被処理品の種類毎に数値化した被処理品の鋼材補正係数と、
に基づいて、雰囲気が有する浸窒(窒化)能力(窒化ポテンシャル)を演算し、
前記演算値と被処理品の窒素濃度の目標値とを比較して、被処理品の窒素濃度が前記目標値となるように前記流量制御弁を制御し、
前記予め求めた相関関係が、
窒化ポテンシャル(%)
=a(T)×In(P NH3 )+b(T)
In:自然対数
NH3 :アンモニアガス分圧
a(T),b(T):浸窒温度Tに依存する変数
で表される、浸窒処理装置。
A processing furnace for performing nitriding treatment on the product to be charged, a flow rate control valve for controlling the supply amount of ammonia gas into the furnace, and a flow rate of ammonia gas supplied into the furnace are detected. An immersion gas analyzer, an ammonia gas analyzer for detecting the partial pressure of ammonia gas in the furnace, a temperature sensor for detecting the temperature in the furnace, and a control device for controlling the flow control valve. A nitrogen treatment device,
The controller is
Information about the type of article to be processed;
Each detected value of the ammonia gas analyzer and the temperature sensor,
A correlation determined in advance, which depends on the temperature in the furnace, between the ammonia gas partial pressure in the furnace and the nitrogen concentration of a specific object to be processed disposed in the furnace;
Steel material correction coefficient of the processed product quantified for each type of processed product based on the nitriding property of the specific processed product,
Based on the above, calculate the nitriding (nitriding) ability (nitriding potential) of the atmosphere,
Comparing the calculated value with the target value of the nitrogen concentration of the product to be processed, and controlling the flow rate control valve so that the nitrogen concentration of the product to be processed becomes the target value ,
The previously determined correlation is
Nitriding potential (%)
= A (T) x In ( PNH3 ) + b (T)
In: Natural logarithm
P NH3 : Ammonia gas partial pressure
a (T), b (T): Variables depending on the nitriding temperature T
Nitrogen treatment equipment represented by
装入された被処理品に浸窒処理を施すための処理炉と、該炉内へのアンモニアガスの供給量を制御する流量制御弁と、前記炉内に供給されるアンモニアガスの流量を検出する流量計と、前記炉内のアンモニアガス分圧を検出するアンモニアガス分析計と、前記炉内の温度を検出する温度センサと、前記流量制御弁を制御する制御装置と、を備えている浸窒処理装置であって、
前記制御装置は、
前記被処理品の種類についての情報と、
浸窒処理時間についての情報と、
前記アンモニアガス分析計及び前記温度センサの各検出値と、
前記炉内のアンモニアガス分圧と前記炉内に配置した特定の被処理品の窒素濃度との間の、前記炉内の温度に依存する、予め求めた相関関係と、
前記特定の被処理品の浸窒性を基準として被処理品の種類毎に数値化した被処理品の鋼材補正係数と、
浸窒処理時間の関数として示される時間補正係数と、
に基づいて、雰囲気が有する浸窒(窒化)能力(窒化ポテンシャル)を演算し、
前記演算値と被処理品の最終窒素濃度の目標値とを比較して、被処理品の窒素濃度が前記目標値となるように前記流量制御弁を制御し、
前記予め求めた相関関係が、
窒化ポテンシャル(%)
=a(T)×In(P NH3 )+b(T)
In:自然対数
NH3 :アンモニアガス分圧
a(T),b(T):浸窒温度Tに依存する変数
で表される、浸窒処理装置。
A processing furnace for performing nitriding treatment on the product to be charged, a flow rate control valve for controlling the supply amount of ammonia gas into the furnace, and a flow rate of ammonia gas supplied into the furnace are detected. An immersion gas analyzer, an ammonia gas analyzer for detecting the partial pressure of ammonia gas in the furnace, a temperature sensor for detecting the temperature in the furnace, and a control device for controlling the flow control valve. A nitrogen treatment device,
The controller is
Information about the type of article to be processed;
Information about nitriding time,
Each detected value of the ammonia gas analyzer and the temperature sensor,
A correlation determined in advance, which depends on the temperature in the furnace, between the ammonia gas partial pressure in the furnace and the nitrogen concentration of a specific object to be processed disposed in the furnace;
Steel material correction coefficient of the processed product quantified for each type of processed product based on the nitriding property of the specific processed product,
A time correction factor expressed as a function of the nitriding time,
Based on the above, calculate the nitriding (nitriding) ability (nitriding potential) of the atmosphere,
Comparing the calculated value and the target value of the final nitrogen concentration of the product to be processed, and controlling the flow rate control valve so that the nitrogen concentration of the product to be processed becomes the target value ,
The previously determined correlation is
Nitriding potential (%)
= A (T) x In ( PNH3 ) + b (T)
In: Natural logarithm
P NH3 : Ammonia gas partial pressure
a (T), b (T): Variables depending on the nitriding temperature T
Nitrogen treatment equipment represented by
前記鋼材補正係数が、複数の被処理品について実データを利用して求めた鋼材補正係数と、前記複数の被処理品の化学成分と、の間に認められる相関関係に基づき、前記複数の被処理品とは別種の被処理品について、該別種の被処理品の化学成分に対応する数値として設定される、請求項6又は7に記載の浸窒処理装置。 The steel material correction coefficient is based on a correlation found between a steel material correction coefficient obtained using actual data for a plurality of products to be processed and chemical components of the plurality of products to be processed. The nitriding treatment apparatus according to claim 6 or 7 , which is set as a numerical value corresponding to a chemical component of a different type of processed product for the processed item different from the processed product. 前記化学成分が、被処理品のクロム含有率である、請求項に記載の浸窒処理装置。 The nitriding apparatus according to claim 8 , wherein the chemical component is a chromium content of a product to be processed. 前記浸窒処理装置が浸炭をともなう浸炭窒化処理を行うことができる装置であることを特徴とする、請求項5乃至9のいずれか一項に記載の浸窒処理装置。   The nitriding apparatus according to any one of claims 5 to 9, wherein the nitriding apparatus is an apparatus capable of performing carbonitriding with carburization.
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