JP2981290B2 - Manufacturing method of galvannealed steel sheet - Google Patents
Manufacturing method of galvannealed steel sheetInfo
- Publication number
- JP2981290B2 JP2981290B2 JP2403803A JP40380390A JP2981290B2 JP 2981290 B2 JP2981290 B2 JP 2981290B2 JP 2403803 A JP2403803 A JP 2403803A JP 40380390 A JP40380390 A JP 40380390A JP 2981290 B2 JP2981290 B2 JP 2981290B2
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- Japan
- Prior art keywords
- sheet
- alloying
- thermometer
- furnace
- average
- Prior art date
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- Vertical, Hearth, Or Arc Furnaces (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、合金化溶融亜鉛めっき
鋼板の製造方法に関する。The present invention relates to a method for producing a galvannealed steel sheet.
【０００２】[0002]
【従来の技術】従来、溶融亜鉛めっき鋼板としては、そ
のめっき層の一部あるいは全体をＦｅ−Ｚｎ合金層とす
るように合金化処理を施した溶融亜鉛めっき鋼板が知ら
れている。このような合金化処理は、図２に示すように
溶融亜鉛めっき槽４の真上に合金化炉２を配置し、めっ
き槽４より引き上げた鋼板１の表面の亜鉛を絞り装置３
により絞って亜鉛付着量の調整を行い、その後直ちに合
金化炉２において鋼板を加熱して亜鉛層へ鉄を拡散させ
ることによりなされ、ここで行われる合金化処理が適正
でない場合、つまり過合金や合金化不足となるとその品
質特性が損なわれるため、合金化処理条件を高精度で制
御する必要がある。2. Description of the Related Art Heretofore, as a hot-dip galvanized steel sheet, there has been known a hot-dip galvanized steel sheet which has been subjected to an alloying treatment so that a part or the whole of a coating layer is formed of an Fe—Zn alloy layer. As shown in FIG. 2, the alloying treatment is performed by arranging the alloying furnace 2 right above the hot-dip galvanizing tank 4 and drawing zinc from the surface of the steel sheet 1 pulled up from the galvanizing tank 4 into a drawing device 3.
The amount of zinc is adjusted by squeezing, and immediately thereafter, the steel sheet is heated in the alloying furnace 2 to diffuse iron into the zinc layer. If the alloying treatment performed here is not appropriate, that is, If the alloying is insufficient, the quality characteristics are impaired. Therefore, it is necessary to control the alloying conditions with high precision.
【０００３】従来、このような合金化処理には次のよう
な困難性があった。 （１） 合金化処理に影響を及ぼす因子としては板温、
亜鉛付着量、めっき槽内アルミ濃度等多くのものがあ
り、合金化炉内での適正熱処理条件を予め明らかにする
のが困難である。 （２） 図３に示すように亜鉛めっき鋼板表面の放射率
は板温により変化し合金化が進行する過程で急変する。
したがって通常、使用されている放射率設定タイプの板
温計（放射温度計）で真の板温を測定することは困難で
ある。 （３） 合金化炉においては鋼板は火炎からの輻射の影
響を強く受けるために炉温制御により熱処理条件を一定
に保つことが困難であった。Conventionally, such an alloying treatment has the following difficulties. (1) Factors affecting the alloying process include sheet temperature and
There are many things such as the amount of zinc attached and the aluminum concentration in the plating tank, and it is difficult to clarify the appropriate heat treatment conditions in the alloying furnace in advance. (2) As shown in FIG. 3, the emissivity of the surface of the galvanized steel sheet changes according to the sheet temperature, and changes rapidly during the progress of alloying.
Therefore, it is usually difficult to measure the true sheet temperature with an emissivity setting type sheet thermometer (radiation thermometer) that is used. (3) In the alloying furnace, since the steel sheet is strongly affected by the radiation from the flame, it is difficult to keep the heat treatment conditions constant by controlling the furnace temperature.
【０００４】従来技術としては、図３に示した亜鉛めっ
き面の放射率急変時に合金化が進行することを利用して
鋼板の輻射エネルギーを測定し、演算器により放射率を
計算し、この放射率より合金化度を推定し、炉温制御に
より合金化度を制御する方法（特開昭５０−６７７３
０）がある。また、輻射エネルギーを測定しその絶対値
を制御することにより合金化度をコントロールする方法
（特開昭５７−１８５９６６）がある。As a conventional technique, the radiant energy of a steel sheet is measured by utilizing the fact that alloying proceeds when the emissivity of the galvanized surface suddenly changes as shown in FIG. 3, and the emissivity is calculated by an arithmetic unit. Method for estimating the degree of alloying from the rate of alloying and controlling the degree of alloying by furnace temperature control (Japanese Patent Laid-Open No. 50-6773)
0). There is also a method of controlling the degree of alloying by measuring the radiant energy and controlling the absolute value (Japanese Patent Laid-Open No. 57-185966).
【０００５】しかし、これらの技術は、 （ａ） 輻射エネルギー値から精度よく放射率を計算す
るのが困難である。 （ｂ） 鋼板の輻射エネルギーは合金化度以外の要因、
例えば浴中Ａｌ濃度や亜鉛付着量等の影響を受けるた
め、輻射エネルギーのみの制御では、合金化度を精度よ
くコントロールすることが難しい。等の欠点があった。However, these techniques are: (a) It is difficult to accurately calculate the emissivity from the radiant energy value. (B) The radiation energy of the steel sheet is a factor other than the degree of alloying,
For example, it is difficult to control the degree of alloying with high accuracy by controlling only the radiant energy because it is affected by the Al concentration in the bath, the amount of zinc attached, and the like. And the like.
【０００６】[0006]
【発明が解決しようとする課題】本発明は上記従来技術
の欠点を解消し、精度よく合金化度をコントロールし、
合金化処理後の鋼板の適正な合金化度を保証する方法を
提供しようとするものである。SUMMARY OF THE INVENTION The present invention solves the above-mentioned disadvantages of the prior art, controls the degree of alloying with high accuracy ,
It is an object of the present invention to provide a method for ensuring an appropriate degree of alloying of a steel sheet after an alloying treatment .
【０００７】[0007]
【課題を解決するための手段】本発明は、合金化処理後
の鋼板の適正な合金化度を保証するために、次の手段を
講じたものである。 合金化炉内に３個以上炉高方向
に順次配置した放射型温度計の指示値が、めっき鋼板の
合金化により放射率が変化することを利用して、隣接す
る温度計の指示値平均の差の減少により、めっき層の合
金化完了位置を正確に求める。 めっき層合金化完了
位置に対応する板温計指示値平均に、炉内最上方に位置
する制御板温計の指示値平均が合致するように合金化炉
の燃料流量を制御する。The present invention employs the following means in order to guarantee a proper degree of alloying of the steel sheet after the alloying treatment. By taking advantage of the fact that emissivity changes by emissivity due to alloying of plated steel sheet, the indicated value of three or more radiation type thermometers arranged sequentially in the furnace height direction in the alloying furnace is The alloying completion position of the plating layer is accurately obtained by reducing the difference. The fuel flow rate of the alloying furnace is controlled such that the average of the indicated values of the plate thermometer located at the uppermost position in the furnace matches the average of the indicated values of the plate thermometer corresponding to the plating layer alloying completion position.
【０００８】[0008]
【作用】以下に本発明の原理を示す。合金化炉に入った
鋼板表面の亜鉛は再溶融し、鋼板との境界面で鋼板中の
鉄分と合金を作りこの合金層が成長し、やがて表面全体
が合金層（固相）で覆われる。このため図３に示したよ
うに放射率εの急激な変化が起る。The principle of the present invention will be described below. The zinc on the surface of the steel sheet that has entered the alloying furnace is remelted to form an alloy with the iron in the steel sheet at the interface with the steel sheet, and this alloy layer grows, and the entire surface is eventually covered with the alloy layer (solid phase). This causes a rapid change in the emissivity ε as shown in FIG.
【０００９】図４に板温計の設定放射率εが０．５の場
合の真の板温と板温計指示値の関係を示す。図３に示す
ように、合金化が進行する過程では鋼板表面の放射率が
急変するために、放射率を予め設定する型式の板温計で
は、真の放射率と板温計への設定放射率とのずれが大き
くなるため、図４に示すＡの部分のように真の板温と板
温計指示値は大きくずれる。図４のＡの部分では真の放
射率と設定放射率の差が大きく、したがって真の板温と
板温計指示値の差は大きい。このＡの部分で真の板温が
１０℃振れると、板温指示値は１００℃程度振れる。ま
た合金化処理が完了すると鋼板の放射率は安定するため
例えば図４のＢの部分のようになる。図４のＢの部分で
は真の板温が１０℃振れたとき、板温計指示値は１０℃
程度の振れとなる。FIG. 4 shows the relationship between the true sheet temperature and the indicated value of the sheet thermometer when the set emissivity ε of the sheet thermometer is 0.5. As shown in FIG. 3, the emissivity of the steel sheet surface changes rapidly during the alloying process. Therefore, in a sheet thermometer of a type in which the emissivity is set in advance, the true emissivity and the set radiation to the sheet thermometer are set. Since the deviation from the rate becomes large, the true sheet temperature and the indicated value of the sheet thermometer are largely shifted as indicated by the portion A in FIG. In part A of FIG. 4, the difference between the true emissivity and the set emissivity is large, and therefore, the difference between the true sheet temperature and the indicated value of the sheet thermometer is large. If the true sheet temperature fluctuates by 10 ° C. in the portion A, the indicated sheet temperature fluctuates by about 100 ° C. When the alloying process is completed, the emissivity of the steel sheet is stabilized, and thus, for example, becomes as shown in part B of FIG. In the part B of FIG. 4, when the true sheet temperature fluctuates by 10 ° C., the indicated value of the sheet thermometer is 10 ° C.
It will be a little swing.
【００１０】本発明はこの現象を利用して、ある一定振
れ幅をもった板温計指示値より板温計指示値平均をもと
める操作を炉高方向に３か所以上行なうことにより合金
化完了位置を求めるものである。図５には、以上の原理
を証明するために、板温指示平均値と指示値振れ幅及び
めっき層中のＦｅ濃度の関係を示す。図５の場合板温指
示平均値が５４５℃〜５５５℃の範囲で指示値振れ幅が
小（約５℃）となり、その時にめっき層中Ｆｅ濃度は１
２〜１３％となり、ほぼ最適合金化度となる。つまり、
指示値の振れ幅が小となった時の板温指示平均値は合金
化度（めっき層中Ｆｅ濃度）に対応しており、板温指示
平均値を制御することにより合金化度制御が可能とな
る。The present invention utilizes this phenomenon to complete the alloying by performing an operation of obtaining the average of the indicated values of the thermometer from the indicated values of the thermometer having a certain fluctuation width in three or more places in the furnace height direction. The position is obtained. FIG. 5 shows the relationship between the indicated plate temperature average value, the indicated value fluctuation width, and the Fe concentration in the plating layer in order to prove the above principle. In the case of FIG. 5, the indicated value fluctuation width becomes small (about 5 ° C.) when the indicated sheet temperature average value is in the range of 545 ° C. to 555 ° C., and at that time, the Fe concentration in the plating layer becomes 1
2 to 13%, which is almost the optimum degree of alloying. That is,
The indicated average value of the sheet temperature when the fluctuation of the indicated value is small corresponds to the degree of alloying (Fe concentration in the plating layer), and the degree of alloying can be controlled by controlling the indicated average value of the sheet temperature. Becomes
【００１１】以下に各板温計の指示値平均より合金化完
了位置を把握する方法を示す。図６に概要を示すよう
に、合金化炉２に５個の板温計１１，１２，１３，１
４，１５を炉高方向に順次設置し、制御用板温計２１を
設置した場合を例にして合金化完了位置を見出す例を説
明する。 各板温計の板温平均基準値Ｔs（℃）：鋼
種毎に板温指示値平均値とめっき層の鉄濃度（合金化
度）を求めておき目標の合金化度によって設定する。隣
接板温計の平均値の差の基準値ΔＴs（℃）：鋼種毎に
板温指示値平均値と指示値振れ幅およびめっき層の鉄濃
度（合金化度）を求めておき、指示値振れ幅が小となる
領域を基準として設定する。 各板温計の指示値平均
と板温平均基準値Ｔs（℃）との比較、及び各隣接板温
計の平均値の差と平均値の差の基準値ΔＴs（℃）との
比較を行なう。A method for grasping the alloying completion position from the average of the indicated values of the respective sheet thermometers will be described below. As shown in FIG. 6, five sheet thermometers 11 , 12 , 13, 1
An example of finding the alloying completion position will be described by taking as an example a case where the control plate thermometer 21 is installed and the control plate thermometer 21 is installed sequentially in the furnace height direction. Average temperature T s (° C) of each sheet thermometer : steel
Average sheet temperature reading and iron concentration of plating layer (alloy
Degree), and set according to the target degree of alloying. Reference value ΔT s (° C) of difference between average values of adjacent sheet thermometers : For each steel type
Sheet temperature indicated value average and indicated value fluctuation range and iron concentration of plating layer
Degree (alloying degree) is obtained, and the indicated value fluctuation width becomes small
Set based on the area . Comparison with comparison of the readings of each plate thermometers mean and sheet temperature average reference value T s (℃), and the reference value [Delta] T s of the difference between the average value and the difference between the average values of each adjacent plate thermometers (℃) Perform
【００１２】板温計１１，１２，１３，１４，１５のそ
れぞれの指示値平均をＴ1 ，Ｔ2 ，Ｔ3 ，Ｔ4 ，Ｔ5と
する。また隣接板温計の指示値平均の差を次のように定
める。 ΔＴA ＝Ｔ2 −Ｔ1 ， ΔＴB ＝Ｔ3 −Ｔ2 ， ΔＴC ＝Ｔ4 −Ｔ3 ， ΔＴD ＝Ｔ5 −Ｔ4 ， 以下、次の各ケースについて判断する。The averages of the indicated values of the sheet thermometers 11, 12, 13, 14, and 15 are defined as T 1 , T 2 , T 3 , T 4 , and T 5 . The difference between the averages of the indicated values of the adjacent sheet thermometers is determined as follows. ΔT A = T 2 −T 1 , ΔT B = T 3 −T 2 , ΔT C = T 4 −T 3 , ΔT D = T 5 −T 4 , and the following cases are determined.
【００１３】ケース１：（図７ａ） Ｔ1 〜Ｔ5 が全てＴs より高く、かつ隣接板温計の指示
値平均の差が全てΔＴ s より低いとき：過合金（パウダ
リング不良）と判断し制御用板温計２１に対する設定値
をΔＴ1 （℃）下げる。ここでΔＴ1 は実操業で得られ
る経験値より定めた設定値である。Case 1: (FIG. 7a) T1 ~ TFive Is all Ts Higher and adjacent plate thermometer indication
The difference between the value averages is ΔT s When lower: overalloy (powder
Set value for control plate thermometer 21
To ΔT1 (° C) Where ΔT1 Is obtained in actual operation
This is a set value determined from experience values.
【００１４】ケース２：（図７ｂ） Ｔ1 〜Ｔ5 が全てＴs より低く、かつ隣接板温計の平均
値の差が全てΔＴs より低いとき：合金化不足（焼けむ
ら）と判断し制御用板温計２１に対する設定値をΔＴ2
（℃）を上げる。ここでΔＴ2 は実操業で得られる経験
値を基にして定めた設定値である。Case 2: (FIG. 7b) When T 1 to T 5 are all lower than T s and the difference between the average values of the adjacent sheet thermometers is all lower than ΔT s : it is judged that alloying is insufficient (burn unevenness). The set value for the control plate thermometer 21 is ΔT 2
(° C). Here, ΔT 2 is a set value determined based on the experience value obtained in the actual operation.
【００１５】ケース３： 板温平均値を連ねる線に屈曲点が認められる場合は、隣
接板温計の平均値の差とその基準値との比較により合金
化完了位置を判定する。具体的には次の手順による。 ｏ ΔＴA ＝Ｔ2 −Ｔ1 ≦ΔＴs であれば板温計１１の
位置で合金化完了と判断し、制御用板温計２１に対する
設定値を板温計１１の指示値平均とする。Case 3: When a bending point is found in the line connecting the average sheet temperature values, the alloying completion position is determined by comparing the difference between the average values of adjacent sheet thermometers and its reference value. Specifically, the following procedure is used. o If ΔT A = T 2 −T 1 ≦ ΔT s , it is determined that alloying is completed at the position of the sheet thermometer 11, and the set value for the control sheet thermometer 21 is set as the average of the indicated values of the sheet thermometer 11.
【００１６】ｏ ΔＴB ＝Ｔ3 −Ｔ2 ≦ΔＴs であれ
ば、板温計１２の位置で合金化完了と判断し、制御用板
温計２１に対する設定値を板温計１２の指示値平均とす
る。 ｏ ΔＴC ＝Ｔ4 −Ｔ3 ≦ΔＴs であれば（図７Ｃ）、
板温計１３の位置で合金化完了と判断し、制御用板温計
２１に対する設定値を板温計１３の指示値平均とする。If o ΔT B = T 3 −T 2 ≦ ΔT s , it is determined that alloying is completed at the position of the sheet thermometer 12 and the set value for the control sheet thermometer 21 is indicated by the indicated value of the sheet thermometer 12. Average. o If ΔT C = T 4 −T 3 ≦ ΔT s (FIG. 7C),
It is determined that alloying is completed at the position of the sheet thermometer 13, and the set value for the control sheet thermometer 21 is set as the average of the indicated values of the sheet thermometer 13.
【００１７】ｏ ΔＴD ＝Ｔ5 −Ｔ4 ≦ΔＴs であれば
板温計１４の位置で合金化完了と判断し、制御用板温計
２１に対する設定値を板温計１４の指示値平均とする。 ケース４： 以上の何れでもないとき（図７ｄ）：合金化不足（焼け
むら）と判断し、制御用板温計２１に対する設定値をΔ
Ｔ（℃）上げる。If o ΔT D = T 5 −T 4 ≦ ΔT s , it is determined that alloying is completed at the position of the sheet thermometer 14, and the set value for the control sheet thermometer 21 is averaged by the indicated value of the sheet thermometer 14. And Case 4: None of the above (FIG. 7d): It is determined that alloying is insufficient (uneven burning), and the set value for the control plate thermometer 21 is Δ
Increase T (° C).
【００１８】板温計は３個あれば指示値平均間の差が２
個得られ本発明の目的を達することができるが、４個以
上配置すれば、炉内の合金化の状態をさらに精密に把握
することができる。If there are three sheet thermometers, the difference between the indicated value averages is 2
Although the object of the present invention can be attained by arranging it, if four or more are arranged, the state of alloying in the furnace can be grasped more precisely.
【００１９】[0019]
【実施例】〔実施例１〕図１に実施例に用いた装置の概
要を示す。合金化炉２の全長は４０ｍであり、通板速度
範囲は、目標目付量、板厚によって変化し６０〜１２０
ｍ／ｍｉｎである。[Embodiment 1] FIG. 1 shows an outline of an apparatus used in the embodiment. The total length of the alloying furnace 2 is 40 m, and the range of the sheet passing speed varies depending on the target basis weight and the sheet thickness.
m / min.
【００２０】合金化炉２の出側より５ｍ、１０ｍ及び１
５ｍの位置にそれぞれ放射温度計である板温計８，７及
び６を配置し、鋼板の板幅方向中心位置にて、めっき鋼
板１の板温指示値平均を求めた。当初、板温計６に合金
化目標温度を設定し、合金化炉の燃料ガス流量を制御し
た。その後、各板温計６，７，８の指示値平均の差を差
の基準値と比較し変化率より合金化完了位置を求め、板
温計８を制御用板温計として合金化完了位置に相当する
板温計の指示値平均に合わせ、その合金化目標温度にな
るように合金化炉の燃料ガス流量を制御した。なお、本
実施例では板温計のいずれか一つと制御用板温計を兼用
するようにしたが、前述したように制御用板温計を別途
設けてもよい。この場合は、炉内の最上方にとりつける
ことが好ましい。 5 m, 10 m and 1 m from the exit side of the alloying furnace 2
The sheet temperature gauge 8,7 and 6 are each radiation thermometer disposed at a position of 5 m, at the plate width direction center position of the steel sheet was determined sheet temperature indication Netaira Hitoshi plated steel sheet 1. Initially, the alloying target temperature was set in the sheet thermometer 6, and the fuel gas flow rate of the alloying furnace was controlled. After that, the difference between the average of the indicated values of the sheet thermometers 6, 7, and 8 is compared with the reference value of the difference, and the alloying completion position is obtained from the rate of change. And the fuel gas flow rate of the alloying furnace was controlled so as to reach the alloying target temperature. The book
In the embodiment, one of the plate thermometers is used as the control plate thermometer.
However, as described above, a separate control plate thermometer was
It may be provided. In this case, attach to the top of the furnace
Is preferred.
【００２１】このようにして製造した５０コイルのサン
プル２００個について評価をしたところ、表１の結果と
なった。Evaluation was made on 200 samples of the 50 coils manufactured in this manner, and the results are shown in Table 1.
【００２２】[0022]
【表１】 ─────────────────────────────────── 焼けむら発生率 パウダリング不良率 （目視による） （１８０°曲げ試験による） 従来法 ６／２００（３％） ４１／２００（２０．５％） 本発明法 ２／２００（１％） ３／２００（１．５％） ─────────────────────────────────── 焼けむらについては、従来も操業者が合金化炉出側にて
板面を観察し操業していたために発生率が低かったが本
発明によりさらに低くなった。パウダリングについて
は、従来はチェックする手段がないために全く管理され
ていなかったが本発明により激減した。[Table 1] 発 生 Burning unevenness rate Powdering defect rate (visually (Based on 180 ° bending test) Conventional method 6/200 (3%) 41/200 (20.5%) Method of the present invention 2/200 (1%) 3/200 (1.5%) ─────む Regarding uneven burns, operators have conventionally cleaned the plate surface on the exit side of the alloying furnace. The incidence was low due to observation and operation, but was further reduced by the present invention. Powdering has not been controlled at all because there is no means for checking in the past, but has been drastically reduced by the present invention.
【００２３】〔実施例２〕実施例１に用いた装置を用
い、ラインスピード１２０ｍ／ｍｉｎで正常な操業をし
ていたラインが、操業上の事情によりラインスピード９
０ｍ／ｍｉｎにダウンした場合の過度期間における本発
明による操業の実施例について、表２を参照して説明す
る。[Embodiment 2] Using the apparatus used in Embodiment 1, a line which had been operating normally at a line speed of 120 m / min was changed to a line speed of 9 due to operational circumstances.
An example of the operation according to the present invention in an excessive period when the speed is reduced to 0 m / min will be described with reference to Table 2.
【００２４】[0024]
【表２】 [Table 2]
【００２５】表２は状態１から状態５に至る経時変化の
データである。状態１では、ラインスピード１２０ｍ／
ｍｉｎ、炉の設定温度４８５℃で定常状態で操業してい
た。この炉の基準値は、過去の操業データから、 各板温計指示値平均基準値Ｔs ：４８２℃ 隣接板温計の平均値の差の基準値ΔＴs ：１０℃ としていた。この時板温計６，７，８の指示値平均は各
々４７０℃，４８１℃，４８５℃であった。平均値の差
は１１℃，４℃であり、板温計８の位置で鋼板の合金化
が完了していた。Table 2 shows data on changes with time from state 1 to state 5. In state 1, the line speed is 120 m /
min, the furnace was operated in a steady state at a set temperature of 485 ° C. The reference value of this furnace was set to the reference value ΔT s : 10 ° C. of the difference between the average values of the adjacent sheet thermometers, based on the past operation data, and the average reference value T s of each sheet thermometer: 482 ° C. At this time, the indicated values of the plate thermometers 6, 7, and 8 were 470 ° C., 481 ° C., and 485 ° C., respectively. The difference between the average values was 11 ° C. and 4 ° C., and the alloying of the steel sheet was completed at the position of the sheet thermometer 8.
【００２６】ラインスピードが１２０ｍ／ｍｉｎから９
０ｍ／ｍｉｎにダウンしたとき合金化炉出側板温がアッ
プし、板温計６，７，８の指示値平均はそれぞれ４８６
℃，４９２℃，４９６℃となった（状態２）。各板温計
指示値平均は指示値平均基準値Ｔs （４８２℃）よりい
ずれも大であり、隣接板温計の平均の差の基準値ΔＴ s
（１０℃）より小であるため、炉の設定温度を経験に基
づきΔＴ（３℃）下げ４８２℃にした。従って、燃料ガ
ス（コークス炉ガス）量も自動的に４００Ｎｍ 3 ／ｈｒ
に下げた。燃料ガス量を下げ、炉況が安定するのをおよ
そ１０秒間待った。Line speed from 120 m / min to 9
When the speed of the alloying furnace is reduced to 0 m / min,
The average readings of the plate thermometers 6, 7, and 8 were 486 each.
° C, 492 ° C, and 496 ° C (state 2). Each plate thermometer
The indicated value average is the indicated value average reference value Ts (482 ° C)
The deviation is also large, and the reference value ΔT of the average difference between adjacent plate thermometers is used. s
(10 ° C), so the furnace temperature can be set based on experience.
Then, the temperature was lowered by ＴT (3 ° C) to 482 ° C. Therefore, the fuel gas
(Coke oven gas) amount is automatically 400Nm Three / Hr
Lowered to Reduce the amount of fuel gas and allow the reactor conditions to stabilize.
I waited 10 seconds.
【００２７】炉況が安定しつつある時、各板温計６，
７，８の指示値平均は４７５℃，４８０℃，４８５℃、
隣接する板温計の平均の差は５℃，５℃となった（状態
３）。各板温計の指示値平均が平均基準値Ｔs （４８２
℃）より小となり隣接する板温計の平均の差が急激に小
さくなっている板温計７に着目して、合金化完了位置を
板温度計７の位置と判定した。この時板温計７の指示値
平均は４８０℃であったの炉での設定温度を４８０℃に
するのが妥当と判断した。When the furnace condition is stable, each plate thermometer 6,
The average readings of 7, 8 are 475 ° C, 480 ° C, 485 ° C,
The average difference between adjacent thermometers was 5 ° C. and 5 ° C. (state 3). The average of the indicated values of each sheet thermometer is the average reference value T s (482
C), the alloying completion position was determined to be the position of the sheet thermometer 7 by focusing on the sheet thermometer 7 in which the average difference between the adjacent sheet thermometers was sharply reduced. At this time, the average of the indicated values of the sheet thermometer 7 was 480 ° C., but it was judged appropriate to set the temperature set in the furnace to 480 ° C.
【００２８】このため、炉の設定温度をさらにΔＴ（２
℃）下げて４８０℃とし、燃料ガス量を自動的に３２０
Ｎｍ3 ／ｈｒに下げ、炉況が安定するのを待った。板温
計６，７，８の指示値平均はそれぞれ４７０℃，４７５
℃，４８０℃となり、各板温計の指示値平均が指示値平
均基準値Ｔs （４８０℃）より小となり、隣接する板温
計指示値平均の差（５℃，５℃）が平均値の差の基準値
ΔＴs （１０℃）より小となる板温計８の位置で鋼板の
合金化が完了していると判断した（状態４）。For this reason, the set temperature of the furnace is further increased by ΔT (2
℃) to 480 ℃, and the amount of fuel gas is automatically reduced to 320 ℃.
Nm 3 / hr, and waited for the furnace conditions to stabilize. The average readings of the plate thermometers 6, 7, and 8 are 470 ° C and 475, respectively.
° C, 480 ° C, the average of the indicated values of each sheet thermometer becomes smaller than the indicated value average reference value T s (480 ° C), and the difference (5 ° C, 5 ° C) between the adjacent sheet thermometer indicated value averages is the average value. It is determined that the alloying of the steel sheet has been completed at the position of the sheet thermometer 8 which is smaller than the reference value ΔT s (10 ° C.) of the difference (state 4).
【００２９】更に数分経過後、炉況が完全に安定し、ラ
インスピード９０ｍ／ｍｉｎで炉の操業を継続すること
ができた。合金化完了位置も板温計８の位置でラインス
ピード１２０ｍ／ｍｉｎの時と変わらなかった。以上の
ようにラインスピードが変わっても、即応して炉の温度
をコントロールすることが可能となり、表２の状態１か
ら状態５になるまでに要した時間はほぼ２分であった。
この間、鋼板は９０×２＝１８０ｍ進んだが、パウダリ
ングやや不良箇所は１．５ｍのみであった。After several minutes, the furnace condition was completely stabilized, and the furnace operation could be continued at a line speed of 90 m / min. The alloying completion position was the same as the position of the sheet thermometer 8 at the line speed of 120 m / min. As described above, even if the line speed changes, the temperature of the furnace can be controlled immediately, and the time required from the state 1 to the state 5 in Table 2 was about 2 minutes.
During this time, the steel sheet advanced by 90 × 2 = 180 m, but the powdering was slightly defective at only 1.5 m.
【００３０】[0030]
【発明の効果】本発明によれば、合金化炉内の合金化完
了位置の把握及び制御を行うことにより、従来法に比べ
てはるかに低い焼けむら及びパウダリング発生率とな
り、鋼板の合金化度を適正に保つことができる。なお、
本発明に用いる板温計としては、一般に市販されている
プロフィール型板温計も使用可能である。According to the present invention, by grasping and controlling the alloying completion position in the alloying furnace, the rate of occurrence of burn unevenness and powdering becomes much lower than in the conventional method, and The degree can be kept properly. In addition,
As the sheet thermometer used in the present invention, a profile-type sheet thermometer that is generally commercially available can also be used.
【図１】本発明の実施例に用いた合金化炉の説明図であ
る。FIG. 1 is an explanatory view of an alloying furnace used in an example of the present invention.
【図２】従来の合金化炉の説明図である。FIG. 2 is an explanatory view of a conventional alloying furnace.
【図３】溶融亜鉛めっき鋼板の板温と放射率の関係を示
すグラフである。FIG. 3 is a graph showing the relationship between the sheet temperature and the emissivity of a galvanized steel sheet.
【図４】真の板温と板温計指示値の関係を示すグラフで
ある。FIG. 4 is a graph showing a relationship between a true sheet temperature and an indicated value of a sheet thermometer.
【図５】板温指示平均値と指示値振れ幅及びめっき層中
のＦｅ濃度の関係を示すグラフである。FIG. 5 is a graph showing the relationship between the indicated sheet temperature average value, the indicated value fluctuation width, and the Fe concentration in the plating layer.
【図６】本発明に用いられる合金化炉の一例における板
温計の配列を示す説明図である。FIG. 6 is an explanatory view showing an arrangement of sheet thermometers in an example of the alloying furnace used in the present invention.
【図７】合金化完了位置を見出す各種ケースの説明図で
ある。FIG. 7 is an explanatory view of various cases for finding an alloying completion position.
１ めっき鋼板 ２ 合金化炉 ３ 絞り装置 ４ めっき槽 ５ シンクロール ６ 板温計 ７ 板温計 ８ 板温計 １１ 板温計 １２ 板温計 １３ 板温計 １４ 板温計 １５ 板温計 ２１ 制御用板温計 DESCRIPTION OF SYMBOLS 1 Plating steel plate 2 Alloying furnace 3 Drawing device 4 Plating tank 5 Sink roll 6 Sheet thermometer 7 Sheet thermometer 8 Sheet thermometer 11 Sheet thermometer 12 Sheet thermometer 13 Sheet thermometer 14 Sheet thermometer 15 Sheet thermometer 21 Control Plate thermometer
───────────────────────────────────────────────────── フロントページの続き (72)発明者 戸村 寧男 千葉市川崎町１番地 川崎製鉄株式会社 千葉製鉄所内 (72)発明者 秋吉 勝則 千葉市川崎町１番地 川崎製鉄株式会社 千葉製鉄所内 (58)調査した分野(Int.Cl.6，ＤＢ名) C23C 2/00 - 2/40 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Norio Tomura 1 Kawasaki-cho, Chiba-shi Kawasaki Steel Corporation Chiba Works (72) Inventor Katsunori Akiyoshi 1 Kawasaki-cho Chiba City Kawasaki Steel Corporation Chiba Works (58 ) Surveyed field (Int.Cl. 6 , DB name) C23C 2/00-2/40
Claims (1)
っき鋼板を前記溶融亜鉛めっき槽の直上に鋼板の入口を
下にして配された溶融亜鉛めっき用合金化炉内を通過さ
せて合金化するに際し、合金化炉内に放射型温度計から
なる板温計を３個以上炉高方向に順次配置し、隣接する
板温計の指示値平均間の差を炉の下方より逐次求め、該
差が予め定めた基準値以下に初めてなる隣接する板温計
のうちの下方の板温計の位置を合金化完了位置として把
握し、制御用板温計の指示値平均が、該合金化完了位置
にある板温計の指示平均値に合致するように合金化炉の
燃料流量を制御することを特徴とする合金化溶融亜鉛め
っき鋼板の製造方法。1. A steel sheet is immersed in a hot-dip galvanizing tank, and the steel sheet is placed immediately above the hot-dip galvanizing tank with an inlet of the steel sheet.
Passed through the hot-dip galvanizing alloying furnace
At the time of alloying, three or more plate thermometers composed of radiation thermometers are sequentially arranged in the alloying furnace in the furnace height direction, and the difference between the indicated value averages of adjacent plate thermometers is determined from the bottom of the furnace. Sequentially obtained, grasp the position of the lower sheet thermometer among the adjacent sheet thermometers whose difference is less than or equal to a predetermined reference value as the alloying completion position, and the indicated value average of the control sheet thermometer is, A method for producing an alloyed hot-dip galvanized steel sheet, comprising controlling a fuel flow rate of an alloying furnace so as to match an indicated average value of a sheet thermometer at the alloying completion position.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2403803A JP2981290B2 (en) | 1990-12-19 | 1990-12-19 | Manufacturing method of galvannealed steel sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2403803A JP2981290B2 (en) | 1990-12-19 | 1990-12-19 | Manufacturing method of galvannealed steel sheet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04218654A JPH04218654A (en) | 1992-08-10 |
| JP2981290B2 true JP2981290B2 (en) | 1999-11-22 |
Family
ID=18513530
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2403803A Expired - Fee Related JP2981290B2 (en) | 1990-12-19 | 1990-12-19 | Manufacturing method of galvannealed steel sheet |
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| Country | Link |
|---|---|
| JP (1) | JP2981290B2 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103764867B (en) | 2011-08-26 | 2016-05-25 | 新日铁住金株式会社 | Alloying location determining method, alloying position determining means |
| JP5673586B2 (en) * | 2012-03-23 | 2015-02-18 | Ｊｆｅスチール株式会社 | Method for calculating degree of alloying of hot-dip galvanized steel sheet and method for controlling alloying |
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1990
- 1990-12-19 JP JP2403803A patent/JP2981290B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04218654A (en) | 1992-08-10 |
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