JP4710053B2

JP4710053B2 - Method and apparatus for measuring carbon concentration in reduced-pressure atmosphere

Info

Publication number: JP4710053B2
Application number: JP2001168472A
Authority: JP
Inventors: 英寿十良澤; 敬二横瀬; 文隆虻川; 淳高橋; 寿海老原
Original assignee: Dowa Thermotech Co Ltd
Current assignee: Dowa Thermotech Co Ltd
Priority date: 2001-06-04
Filing date: 2001-06-04
Publication date: 2011-06-29
Anticipated expiration: 2021-06-04
Also published as: JP2002365276A

Description

【０００１】
【発明の属する技術分野】
本発明は減圧下における熱処理炉内浸炭雰囲気あるいは無酸化雰囲気の炭素濃度を測定する為の方法及び装置に関するものである。
【０００２】
【従来の技術】
熱処理炉内における浸炭あるいは無酸化雰囲気の炭素濃度を直接計測する為の手段として鋼線法が例えば特公昭45−35411号公報に示されている。
【０００３】
また、炭素濃度測定用鋼線を保持する為の保持棒に関しては、例えば実用新案第2586972号に示されたものがある。
【０００４】
【発明が解決しようとする課題】
然しながら、鋼線法での測定は、通常大気圧以上の雰囲気中に炭素濃度測定用鋼線を挿入して行なうものであり、減圧雰囲気中では炭素濃度測定用鋼線を挿入することが困難である。
【０００５】
また、減圧下における真空浸炭は、炭素が直接鋼に侵入する処理であり、炉内雰囲気中の炭素濃度を制御、計測することはなされていない。
【０００６】
本発明は上記の問題を解決したものである。
【０００７】
【課題を解決するための手段】
本発明の減圧雰囲気の炭素濃度測定装置は、炉内に配置した被浸炭処理体を浸炭処理する熱処理炉における処理室内と炉殻外との間を連通する炭素濃度測定体挿入ポートと、上記ポート内を排気する手段及び気密に維持する手段と、上記ポートを介して炭素濃度測定体を上記ポートの炉殻外部分から上記処理室内に搬送する手段と、上記炭素濃度測定体の炭素量を測定する手段とより成ることを特徴とする。
【０００８】
上記ポートの炉殻外部分を気密に維持する手段は、上記搬送手段を締め付け保持可能な手段であることを特徴とする。
【０００９】
本発明の減圧雰囲気の炭素濃度測定方法は、炉内に配置した被浸炭処理体を浸炭処理する熱処理炉における減圧処理室内と炉殻外との間を連通する炭素濃度測定体挿入ポートを排気する工程と、上記ポートの炉殻外部分から上記減圧処理室内に炭素濃度測定体を搬送する工程と、上記炭素濃度測定体を上記処理室内雰囲気と所定時間反応せしめた後上記炭素濃度測定体を所定時間除冷する工程と、この炭素濃度測定体を上記ポートの炉殻外部分に戻し室温迄冷却する工程と、上記炭素濃度測定体の炭素量を大気圧中で測定する工程とより成ることを特徴とする。
【００１０】
上記炭素濃度測定体は、浸炭処理を受ける前の被浸炭処理体のテストピースであることを特徴とする。
【００１１】
【発明の実施の形態】
以下図面によって本発明の実施例を説明する。
【００１２】
図１において１は炉殻、２はこの炉殻１の内側に設けた断熱層、３はこの断熱層２によって囲まれた処理室を示し、本発明においては、炭素濃度測定体を挿入するポート４を炉殻１外から処理室３内に貫通して設け、このポート４にはその炉殻１外部分と処理室３内部分を隔離する為の仕切弁５、ポート４内を大気圧に戻す為のリーク弁６、ポート４内を排気する為に必要な排気弁７、真空ポンプ８、真空計を付帯した装置９を設ける。
【００１３】
また、炭素濃度測定用鋼線１０を保持棒１１の先端に収納し、この保持棒１１に対する締め付け力調整可能な真空シールを有するフランジ１２を挿入ポートフランジ１３に取り付け、排気弁７を開いて挿入ポート４内を真空ポンプ８にて排気する。ポート４内が十分排気されたことを真空計で確認した後、排気弁７を閉じ仕切弁５を開いて処理室３とポート４内を連通させる。締め付け力調整可能な真空シールを緩め保持棒１１をポート４によってガイドしてその先端が処理室３内に挿入された所で、保持棒１１が処理室３内に引き込まれないよう真空シールを締めておく。処理室３内の雰囲気と所定時間反応させた後、真空シールを緩めて炭素濃度測定用鋼線１０の収納された保持棒１１先端を炉殻１と断熱層２間の空間１４部まで引き抜き、徐冷する。所定時間、例えば５分経過した後、保持棒１１の先端を仕切弁５の外側まで引き抜き、仕切弁５を閉じ排気弁７を開きポート４内を真空ポンプ８にて排気し、保持棒１１の先端に収納された炭素濃度測定用鋼線１０を室温まで冷却する。冷却後、排気弁７を閉じリーク弁６を開いてポート４内を大気圧に戻し、フランジ１２、１３を切り離して保持棒１１の先端に収納された炭素濃度測定用鋼線１０を取り出し、電気抵抗測定器の接続端子に接続してその電気抵抗値を測定することにより、炭素量を測定する。
【００１４】
（実施例１）
【００１５】
図１に示す装置によって、減圧下における炉内雰囲気の炭素濃度を測定した。
【００１６】
処理条件：炉内温度1223K、圧力100Kpa、53Kpa、27Kpaの各条件にて炉内雰囲気炭素濃度を変化させ、炭素濃度測定用鋼線を用いて、炉内雰囲気炭素濃度を測定し、測定後の鋼線を燃焼分析してその結果と比較した。電気抵抗測定機としては同和鉱業株式会社製のカーボンポテンシャルメーターを用いた。
【００１７】
その結果表１が得られた。
【００１８】
【表１】

【００１９】
表１から明らかなように本発明による抵抗値測定による炭素濃度が燃焼分析による炭素濃度に略一致することが判明した。
【００２０】
なお、本発明においては上記炭素濃度測定用鋼線１０に代えて炭素濃度測定用鋼箔を用いても良い。
【００２１】
また、本発明の他の実施例においては減圧処理室内で被処理体を浸炭処理する場合、浸炭が始まる前に処理室内にテストピースとして、例えば鋼棒を挿入し、浸炭開始から所定時間後、例えば所定浸炭が終了する１５分前に鋼棒を処理室から引き抜き、除冷した後組織を観察し、この結果から処理室の雰囲気炭素濃度、上記挿入時間に対する鋼棒の炭素濃度、浸炭深さ等の浸炭挙動、履歴を求めるようにする。
【００２２】
このようにすれば、処理室内で被処理体に予定している浸炭品質が得られているか否かが確認でき、そのとき浸炭処理を終了し、被処理体を次工程である拡散処理工程に進めることができるようになる。
【００２３】
【発明の効果】
上記のように本発明によれば従来の熱処理炉内の炭素濃度を直接測定する鋼線法が、減圧下における炉内雰囲気炭素濃度の測定として同じように用いることができ、減圧処理では従来行われていなかった浸炭処理途中での炉内雰囲気炭素濃度というものが簡単に測定できるようになる大きな利益がある。
【図面の簡単な説明】
【図１】本発明の減圧雰囲気の炭素濃度測定方法及び装置の説明図である。
【符号の説明】
１炉殻
２断熱層
３処理室
４ポート
５仕切弁
６リーク弁
７排気弁
８真空ポンプ
９真空計を付帯した装置
１０炭素濃度測定用鋼線
１１保持棒
１２フランジ
１３挿入ポートフランジ
１４空間[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for measuring the carbon concentration in a carburizing atmosphere or non-oxidizing atmosphere in a heat treatment furnace under reduced pressure.
[0002]
[Prior art]
For example, Japanese Patent Publication No. 45-35411 discloses a steel wire method as a means for directly measuring the carbon concentration in a carburizing or non-oxidizing atmosphere in a heat treatment furnace.
[0003]
As for a holding rod for holding a carbon wire for measuring carbon concentration, for example, there is one shown in Utility Model No. 2586972.
[0004]
[Problems to be solved by the invention]
However, measurement by the steel wire method is usually performed by inserting a steel wire for measuring carbon concentration in an atmosphere of atmospheric pressure or higher, and it is difficult to insert the steel wire for measuring carbon concentration in a reduced pressure atmosphere. is there.
[0005]
Moreover, the vacuum carburization under reduced pressure is a process in which carbon directly enters steel, and the carbon concentration in the furnace atmosphere is not controlled or measured.
[0006]
The present invention solves the above problems.
[0007]
[Means for Solving the Problems]
The carbon concentration measuring device for reduced-pressure atmosphere of the present invention includes a carbon concentration measuring body insertion port that communicates between a processing chamber and the outside of the furnace shell in a heat treatment furnace for carburizing a carburized processing body disposed in the furnace, and the port Means for evacuating the interior and means for maintaining airtightness, means for conveying the carbon concentration measuring body from the outer shell portion of the port to the processing chamber via the port, and measuring the carbon content of the carbon concentration measuring body. And means.
[0008]
The means for keeping the port outside the furnace shell airtight is a means capable of tightening and holding the transport means.
[0009]
The method for measuring carbon concentration in a reduced pressure atmosphere of the present invention exhausts the carbon concentration measuring body insertion port communicating between the reduced pressure processing chamber and the outside of the furnace shell in a heat treatment furnace for carburizing the carburized body disposed in the furnace. A step of transporting a carbon concentration measuring body from the outside of the furnace shell of the port into the reduced pressure processing chamber, and reacting the carbon concentration measuring body with the atmosphere in the processing chamber for a predetermined time, A step of cooling, a step of returning the carbon concentration measuring body to the outside of the furnace shell of the port and cooling to room temperature, and a step of measuring the carbon content of the carbon concentration measuring body at atmospheric pressure. And
[0010]
The carbon concentration measuring body is a test piece of a carburized body before being subjected to carburizing treatment .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0012]
In FIG. 1, 1 is a furnace shell, 2 is a heat insulating layer provided inside the furnace shell 1, 3 indicates a processing chamber surrounded by the heat insulating layer 2, and in the present invention, a port into which a carbon concentration measuring body is inserted. 4 is provided penetrating from the outside of the furnace shell 1 into the processing chamber 3. This port 4 has a gate valve 5 for isolating the outer portion of the furnace shell 1 from the inner portion of the processing chamber 3, and the inside of the port 4 is brought to atmospheric pressure. A leak valve 6 for returning, an exhaust valve 7 necessary for exhausting the inside of the port 4, a vacuum pump 8, and a device 9 attached with a vacuum gauge are provided.
[0013]
A steel wire 10 for measuring carbon concentration is housed at the tip of the holding rod 11, a flange 12 having a vacuum seal capable of adjusting the tightening force with respect to the holding rod 11 is attached to the insertion port flange 13, and the exhaust valve 7 is opened for insertion. The inside of the port 4 is evacuated by the vacuum pump 8. After confirming that the inside of the port 4 is sufficiently evacuated with a vacuum gauge, the exhaust valve 7 is closed and the gate valve 5 is opened to allow the processing chamber 3 and the port 4 to communicate with each other. The vacuum seal whose tightening force can be adjusted is loosened, the holding rod 11 is guided by the port 4, and the tip is inserted into the processing chamber 3, and the vacuum seal is tightened so that the holding rod 11 is not drawn into the processing chamber 3. Keep it. After reacting with the atmosphere in the processing chamber 3 for a predetermined time, the vacuum seal is loosened, and the tip of the holding rod 11 in which the carbon concentration measuring steel wire 10 is housed is pulled out to a space 14 between the furnace shell 1 and the heat insulating layer 2, Slowly cool. After a predetermined time, for example, 5 minutes, the tip of the holding rod 11 is pulled out to the outside of the gate valve 5, the gate valve 5 is closed, the exhaust valve 7 is opened, the inside of the port 4 is evacuated by the vacuum pump 8, The carbon wire 10 for measuring carbon concentration stored at the tip is cooled to room temperature. After cooling, the exhaust valve 7 is closed, the leak valve 6 is opened, the inside of the port 4 is returned to atmospheric pressure, the

flanges

12 and 13 are disconnected, and the carbon concentration measurement steel wire 10 stored at the tip of the holding rod 11 is taken out. The amount of carbon is measured by connecting to a connection terminal of a resistance measuring instrument and measuring its electrical resistance value.
[0014]
Example 1
[0015]
The carbon concentration in the furnace atmosphere under reduced pressure was measured with the apparatus shown in FIG.
[0016]
Treatment conditions: In-furnace temperature 1223K, pressures 100Kpa, 53Kpa, 27Kpa, change the furnace atmosphere carbon concentration, measure the furnace atmosphere carbon concentration using the carbon wire for carbon concentration measurement, after the measurement The steel wire was subjected to combustion analysis and compared with the results. A carbon potential meter manufactured by Dowa Mining Co., Ltd. was used as the electrical resistance measuring machine.
[0017]
As a result, Table 1 was obtained.
[0018]
[Table 1]

[0019]
As is apparent from Table 1, it was found that the carbon concentration obtained by resistance measurement according to the present invention substantially coincided with the carbon concentration obtained by combustion analysis.
[0020]
In the present invention, a carbon foil for measuring carbon concentration may be used instead of the steel wire 10 for measuring carbon concentration.
[0021]
In another embodiment of the present invention, when carburizing the object to be processed in the reduced pressure processing chamber, for example, a steel bar is inserted into the processing chamber as a test piece before the carburizing starts, and after a predetermined time from the start of carburizing, For example, the steel bar is pulled out from the processing chamber 15 minutes before the end of the predetermined carburizing, and after cooling, the structure is observed. From the results, the atmospheric carbon concentration in the processing chamber, the carbon concentration of the steel rod with respect to the insertion time, the carburizing depth Carburizing behavior and history such as
[0022]
In this way, it can be confirmed whether or not the carburizing quality scheduled for the object to be processed is obtained in the processing chamber. At that time, the carburizing process is ended, and the object to be processed is subjected to the diffusion process step as the next step. You will be able to proceed.
[0023]
【The invention's effect】
As described above, according to the present invention, the steel wire method for directly measuring the carbon concentration in the conventional heat treatment furnace can be used in the same manner as the measurement of the atmospheric carbon concentration in the furnace under reduced pressure. There is a great advantage that the carbon concentration in the furnace during the carburizing process, which was not known, can be easily measured.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a method and apparatus for measuring carbon concentration in a reduced-pressure atmosphere according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Furnace shell 2 Heat insulation layer 3 Processing chamber 4 Port 5 Gate valve 6 Leak valve 7 Exhaust valve 8 Vacuum pump 9 Equipment attached with vacuum gauge 10 Carbon wire for measuring carbon concentration 11 Holding rod 12 Flange 13 Insertion port flange 14 Space

Claims

A carbon concentration measuring body insertion port communicating between the processing chamber and the outside of the furnace shell in the heat treatment furnace for carburizing the carburized body disposed in the furnace, means for exhausting the inside of the port, and means for maintaining airtightness And a means for conveying the carbon concentration measuring body from the outer shell portion of the port to the processing chamber through the port, and a means for measuring the carbon content of the carbon concentration measuring body. Carbon concentration measuring device.

The carbon concentration measuring device in a reduced-pressure atmosphere according to claim 1, wherein the carbon concentration measuring body is a carbon wire for measuring carbon concentration.

The apparatus for measuring carbon concentration in a reduced-pressure atmosphere according to claim 1, wherein the carbon concentration measuring body is a steel foil.

2. The carbon concentration measuring apparatus in a reduced pressure atmosphere according to claim 1, wherein the carbon concentration measuring body is a test piece of a carburized body before being subjected to carburizing treatment .

5. The apparatus for measuring a carbon concentration in a reduced-pressure atmosphere according to 1, 2, 3 or 4, wherein the means for maintaining the portion outside the furnace shell of the port airtight is means capable of tightening and holding the transport means.

Evacuating the carbon concentration measuring body insertion port communicating between the decompression chamber and the outside of the furnace shell in the heat treatment furnace for carburizing the carburized body disposed in the furnace, and the decompression from the portion outside the furnace shell of the port A step of transporting the carbon concentration measuring body into the processing chamber, a step of reacting the carbon concentration measuring body with the atmosphere in the processing chamber for a predetermined time, and then cooling the carbon concentration measuring body for a predetermined time; and A method for measuring a carbon concentration in a reduced-pressure atmosphere, comprising: a step of returning to a portion outside the furnace shell of the port and cooling to room temperature; and a step of measuring the carbon content of the carbon concentration measuring body in an atmospheric pressure.

The carbon concentration measuring method in a reduced-pressure atmosphere according to claim 6, wherein the carbon concentration measuring body is a carbon wire for measuring carbon concentration.

The carbon concentration measurement method in a reduced-pressure atmosphere according to claim 6, wherein the carbon concentration measurement body is a steel foil.

The carbon concentration measuring method in a reduced pressure atmosphere according to claim 6, wherein the carbon concentration measuring body is a test piece of a carburized body before being subjected to carburizing treatment .