JPS6259170B2 - - Google Patents
Info
- Publication number
- JPS6259170B2 JPS6259170B2 JP9748280A JP9748280A JPS6259170B2 JP S6259170 B2 JPS6259170 B2 JP S6259170B2 JP 9748280 A JP9748280 A JP 9748280A JP 9748280 A JP9748280 A JP 9748280A JP S6259170 B2 JPS6259170 B2 JP S6259170B2
- Authority
- JP
- Japan
- Prior art keywords
- steel plate
- temperature
- cooling roll
- cooling
- yield point
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 229910000831 Steel Inorganic materials 0.000 claims description 47
- 239000010959 steel Substances 0.000 claims description 47
- 238000001816 cooling Methods 0.000 claims description 44
- 230000008646 thermal stress Effects 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000000704 physical effect Effects 0.000 description 3
- 230000035882 stress Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 2
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
- 230000037303 wrinkles Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/54—Furnaces for treating strips or wire
- C21D9/56—Continuous furnaces for strip or wire
- C21D9/573—Continuous furnaces for strip or wire with cooling
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Control Of Heat Treatment Processes (AREA)
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Description
本発明は連続焼鈍装置等における鋼板等の冷却
方法の改良に関する。
連続焼鈍装置等における鋼板等の冷却には、第
１図ａに示すような冷却ロール１が用いられ、ロ
ール１の内側に形成されたら線状の冷却水通路２
内に冷却水を流し、この冷却ロール１に鋼板等を
接触させて冷却を行なう。そして、必要に応じて
冷却ロール１の数を増減し、例えば第１図ｂに示
すように３個の冷却ロール１が用いられる。この
ような冷却ロール１の設置位置は第２図ａ，ｂ，
ｃに示すように、雰囲気炉３の出口側内部（第２
図ａ）又は炉３の出口に設置されたり（第２図
ｂ）、外気とのシールを必要としない場合には同
図ｃのように炉３外に設置されることもある。
このような冷却ロールで冷却される鋼板等には
通常0.1％前後のかた伸びがあり、冷却ロールへ
の不均一接触による不均一冷却のため熱応力が発
生し、これに起因してしわ等の変形を生じてしま
う。
本発明はかかる従来の冷却方法の欠点を解消
し、冷却ロールによる鋼板等の内部に生じる熱応
力を減じ、変形を防止することのできる冷却ロー
ルによる鋼板等の冷却方法の提供を目的とする。
かかる目的を達成するための本発明の構成は冷却
ロール通過後の鋼板の永久ひずみが最大許容値と
なるときの前記冷却ロールの温度とこのときの接
触開始位置における鋼板の平均温度との温度差を
求め、当該平均温度における鋼板の縦弾性係数と
線膨張係数と前記温度差との積で得られる見掛け
上の熱応力と当該平均温度における鋼板の降伏点
との比を予め求めておき、実際に冷却ロールに導
入された場合の前記平均温度における鋼板の降伏
点よりも当該平均温度における鋼板の見掛け上の
熱応力と前記比との積が小さくなるように冷却ロ
ールの温度を制御するようにしたことを特徴とす
る。
以下、本発明を実施例とともに詳細に説明す
る。
一般に、鋼板の両端を固定し、この鋼板の左右
両端面の温度をＴA，ＴBとして、その温度差をΔ
Ｔとしたモデルで熱応力等について考える。ま
ず、温度差ΔＴによるのびΔＬは次式となる。
ΔＬ＝α・ΔＴ・Ｌ …(1)
ここでα：線膨張係数
Ｌ：鋼板の長さ
また、ひずみεは次式となる。
ε＝α・ΔＴ (2)
このときの熱応力σは次式で与えられる。
σ＝Ｋ・Ｅ・α・ΔＴ …(3)
ここでＫ：係数
Ｅ：縦弾性係数
このようなモデルの場合と同様の現象が実際の
冷却ロールによる鋼板の冷却の際にも局部的に生
じている。したがつて、このとき生ずる熱応力を
鋼板の降伏点以下となるようにすれば鋼板には何
んら変形を生じないことになる。
すなわち、Ｋ・Ｅ・α・ΔＴσB …(4)
なる条件を満たすように温度差ΔＴを制御すれば
良いこととなる。そこで、実際の冷却ロールで
は、この温度差として冷却ロールの温度と鋼板の
この冷却ロールに対する接触開始位置における当
該鋼板の平均温度との温度差を用い、この温度差
によつて生ずる熱応力を降伏点以下とすれば良い
こととなる。
しかし、上記(4)式中の係数Ｋの値がわからない
と鋼板内部に生ずる熱応力を求めることができな
い。
そこで、実験により、この係数Ｋを求める。
今、温度差ΔＴに起因する鋼板の変形を第３図に
示すように仮定し、次式で定義される急峻度δを
用いて表わす。
ここでｌ：鋼板のサンプル長さ
ｈi：鋼板が波形に変形した部分の変形量
ｎ：鋼板のサンプル長さ中の山の数
この急峻度δは冷却後の鋼板の変形割合を示す
ことになり、一般に１％以下であることが要求さ
れる。
次に、板厚0.8mmおよび0.4mmの鋼板を用いて、
冷却ロールの温度と鋼板のこの冷却ロールに対す
る接触開始位置における当該鋼板の平均温度との
温度差ΔＴを変化させ、急峻度δとの関係を求
め、これを、第４図に示した。同図から明らかな
ように、急峻度δが１％以下となるのは温度差Δ
Ｔ＝ΔT0＝250℃までの範囲である。
尚、このときの鋼板の各物性値は次のように与
えられている。
降伏点 σB0＝21.5Kg／mm2
縦弾性係数E0＝1.91×104Kg／mm2
線膨張係数α０＝1.37×10-51/℃
冷却ロール温度＝20℃
また、温度差ΔT0において急峻度δが１％と
詳容範囲ぎりぎりの変形であり、この状態での見
掛け上の熱応力σ０＝E0・α０・ΔT0は降伏点
σB0にほぼ等しい値とみなすことができる。
この結果、温度差ΔT0のときの上記各物性値
から見掛け上の熱応力と降伏点との比である係数
Ｋが得られる。
Ｋ＝σ０／Ｅ０・α０・ΔＴ０≒σＢ０／Ｅ０・α０
・ΔＴ０…(6)
また、降伏点σBについては同一材料でも温度
によつて異なり、温度が高くなると、その降伏点
σBは当然小さくなり、この場合には降伏点以下
に応力を抑えるための温度差を小さくする必要が
生じ、また、同一温度条件でも降伏点の小さい材
料では温度差を小さくしなければ材料の変形を抑
えることはできなくなるはずであり、急峻度δが
許容値に入る時の応力σは降伏点に比例すると考
えて良い。
したがつて、上述のように係数Ｋの値を求め、
これを用いて温度差ΔＴに対する見掛け上の熱応
力σ＝Ｅ・α・ΔＴに係数Ｋを掛け、実際の熱応
力を算出し、次式を満足するように温度差を制御
すれば良い。
ΔＴ≦ΔＴ０・Ｅ０・α０・σＢ／Ｅ・α・σＢ０＝
１／Ｋ・σＢ／Ｅ・α…(7)
この(7)式では、ある状態、すなわち急峻度が１
％以下となる温度差ΔT0のときの降伏点σB0，
縦弾性係数E0，線膨張係数α0.温度差ΔT0，は実
験結果より得られ、冷却ロールの温度と鋼板のこ
の冷却ロールに対する接触開始位置における当該
鋼板の平均温度との温度差と、そのときの降伏点
σB，縦弾性係数Ｅ、線膨張係数αより上記(7)式
を満足するように冷却ロールの温度を決定するこ
とで変形を許容値以下に抑えることができる。
したがつて、第５図ａに示すように３個の冷却
ロール１を用いる場合には、各冷却ロール１の温
度差ΔT1，ΔT2，ΔT3がそれぞれ上記(7)式を満
足するようにすればよく、その冷却状態の一例を
第５図ｂに示した。
また、軟鋼板を用いた場合の接触開始位置での
各温度に対する許容温度差ΔＴは次表のようにな
る。
The present invention relates to an improvement in a method for cooling steel plates, etc. in a continuous annealing apparatus or the like. A cooling roll 1 as shown in FIG.
Cooling water is allowed to flow inside, and a steel plate or the like is brought into contact with this cooling roll 1 for cooling. Then, the number of cooling rolls 1 is increased or decreased as necessary, and for example, three cooling rolls 1 are used as shown in FIG. 1b. The installation position of such a cooling roll 1 is as shown in Fig. 2 a, b,
As shown in c, the inside of the outlet side of the atmospheric furnace 3 (second
a) or at the outlet of the furnace 3 (FIG. 2 b), or if sealing with the outside air is not required, it may be installed outside the furnace 3 as shown in FIG. 2 c. Steel plates, etc. cooled by such cooling rolls usually have an elongation of around 0.1%, and thermal stress is generated due to uneven cooling due to uneven contact with the cooling roll, which causes wrinkles etc. This will cause deformation. An object of the present invention is to provide a method for cooling a steel plate, etc., using a cooling roll, which eliminates the drawbacks of the conventional cooling method, reduces the thermal stress generated inside the steel plate, etc. caused by the cooling roll, and can prevent deformation.
The structure of the present invention to achieve such an object is based on the temperature difference between the temperature of the cooling roll when the permanent strain of the steel plate after passing through the cooling roll reaches the maximum allowable value and the average temperature of the steel plate at the contact start position at this time. The ratio of the apparent thermal stress obtained by multiplying the longitudinal elastic modulus and linear expansion coefficient of the steel plate at the average temperature by the temperature difference and the yield point of the steel plate at the average temperature is determined in advance, and the actual The temperature of the cooling roll is controlled so that the product of the apparent thermal stress of the steel plate at the average temperature and the ratio is smaller than the yield point of the steel plate at the average temperature when introduced into the cooling roll. It is characterized by what it did. Hereinafter, the present invention will be explained in detail together with examples. Generally, both ends of a steel plate are fixed, and the temperatures of the left and right end surfaces of the steel plate are T A and T B , and the temperature difference is Δ
Consider thermal stress, etc. using a model with T. First, the elongation ΔL due to the temperature difference ΔT is expressed by the following equation. ΔL=α・ΔT・L (1) where α: coefficient of linear expansion L: length of the steel plate In addition, the strain ε is given by the following formula. ε=α・ΔT (2) The thermal stress σ at this time is given by the following equation. σ=K・E・α・ΔT …(3) where K: Coefficient E: Longitudinal elastic modulus A phenomenon similar to that in this model occurs locally when a steel plate is actually cooled by a cooling roll. ing. Therefore, if the thermal stress generated at this time is made to be below the yield point of the steel plate, no deformation will occur in the steel plate. That is, it is sufficient to control the temperature difference ΔT so as to satisfy the following condition: K・E・α・ΔTσ B (4). Therefore, in an actual cooling roll, the temperature difference between the temperature of the cooling roll and the average temperature of the steel plate at the position where the steel plate starts contacting the cooling roll is used as the temperature difference, and the thermal stress caused by this temperature difference is reduced. It would be good if it was less than a point. However, unless the value of the coefficient K in the above equation (4) is known, the thermal stress generated inside the steel plate cannot be determined. Therefore, this coefficient K is determined by experiment.
Now, it is assumed that the deformation of the steel plate due to the temperature difference ΔT is as shown in FIG. 3, and is expressed using the steepness δ defined by the following equation. Here, l: sample length of the steel plate h i : amount of deformation of the part where the steel plate is deformed into a wave shape n: number of ridges in the sample length of the steel plate This steepness δ indicates the deformation rate of the steel plate after cooling. Therefore, it is generally required to be 1% or less. Next, using steel plates with thicknesses of 0.8 mm and 0.4 mm,
The temperature difference ΔT between the temperature of the cooling roll and the average temperature of the steel plate at the position where the steel plate starts contacting the cooling roll was varied, and the relationship with steepness δ was determined, and this is shown in FIG. As is clear from the figure, the steepness δ is 1% or less when the temperature difference Δ
The range is up to T=ΔT 0 =250°C. In addition, each physical property value of the steel plate at this time is given as follows. Yield point σ B0 = 21.5Kg/mm 2Longitudinal elastic modulus E 0 = 1.91×10 4 Kg/mm 2 Linear expansion coefficient α 0 = 1.37×10 -5 1/℃ Cooling roll temperature = 20℃ Also, temperature difference ΔT 0 In this case, the steepness δ is 1%, which is at the edge of the detailed range, and the apparent thermal stress σ 0 = E 0 · α 0 · ΔT 0 in this state can be considered to be approximately equal to the yield point σ B0 . can. As a result, a coefficient K, which is the ratio between the apparent thermal stress and the yield point, can be obtained from the above-mentioned physical property values when the temperature difference ΔT 0 is present. K=σ 0 /E 0・α 0・ΔT 0 ≒σB 0 /E 0・α 0
・ΔT 0 ...(6) Also, the yield point σ B of the same material varies depending on the temperature. As the temperature increases, the yield point σ B naturally decreases, and in this case, the stress must be kept below the yield point. In addition, even under the same temperature conditions, if the material has a small yield point, it will not be possible to suppress the deformation of the material unless the temperature difference is reduced, and the steepness δ will not reach the allowable value. It can be considered that the stress σ at the time of entry is proportional to the yield point. Therefore, find the value of the coefficient K as described above,
Using this, the apparent thermal stress σ=E・α・ΔT with respect to the temperature difference ΔT is multiplied by a coefficient K to calculate the actual thermal stress, and the temperature difference can be controlled so as to satisfy the following equation. ΔT≦ΔT 0・E 0・α 0・σ B /E・α・σ B0 =
1/K・σ B /E・α…(7) In this equation (7), in a certain state, that is, when the steepness is 1
The yield point σ B0 when the temperature difference ΔT 0 is less than %,
The longitudinal elastic modulus E 0 , the linear expansion coefficient α 0 , and the temperature difference ΔT 0 are obtained from experimental results, and are the temperature difference between the temperature of the cooling roll and the average temperature of the steel plate at the position where the steel plate starts contacting the cooling roll, By determining the temperature of the cooling roll so as to satisfy the above equation (7) from the yield point σ B , longitudinal elastic modulus E, and linear expansion coefficient α at that time, deformation can be suppressed to below the allowable value. Therefore , when three cooling rolls 1 are used as shown in FIG . An example of the cooling state is shown in FIG. 5b. Further, when a mild steel plate is used, the allowable temperature difference ΔT for each temperature at the contact start position is as shown in the following table.
【表】
実際の冷却に用いる冷却媒体としては高温の場
合にはガス、空気、油あるいは溶融塩等を用いる
ことで適正な温度差とすることができ、冷却ロー
ルの配置も鋼板との接触部分（まきつけ角）をで
きるだけ大きくとり、冷却ロールを離れるときの
鋼板温度がロール温度に近い温度となるようにす
ることで効率的に冷却でき、次段ロール温度決定
のためにも良い。
以上、実施例とともに具体的に説明したように
本発明によれば実験により急峻度が許容値以下と
なるときの温度差ΔT0とこのときの各物性値
E0，α０，σB0を知つておけば、鋼板の平均温度
差によつて異なる熱応力を知り、この応力が降伏
点以下となるように冷却ロールの温度を制御すれ
ば不均一冷却による鋼板の変形を許容値以内に納
めることができる。
尚、上記説明では鋼板について説明したが鋼板
に限らず各種メツキを施こした鋼板も含むもので
ある。[Table] When the temperature is high, gas, air, oil, or molten salt can be used as the cooling medium used for actual cooling to achieve an appropriate temperature difference. By making the winding angle as large as possible so that the temperature of the steel sheet when it leaves the cooling roll is close to the roll temperature, efficient cooling can be achieved, which is also good for determining the temperature of the next stage roll. As explained above in detail with the examples, according to the present invention, the temperature difference ΔT 0 when the steepness becomes less than the allowable value and each physical property value at this time are determined by experiment.
By knowing E 0 , α 0 , and σ B0 , you can know the thermal stress that varies depending on the average temperature difference of the steel plate, and if you control the temperature of the cooling roll so that this stress is below the yield point, you can eliminate uneven cooling. Deformation of the steel plate can be kept within tolerance. Incidentally, in the above description, a steel plate was explained, but the invention is not limited to steel plates, but also includes steel plates with various platings.
第１図ａ，ｂは従来の冷却ロールの説明図、第
２図ａ，ｂ，ｃは冷却ロールの配置場所の説明
図、第３図は鋼板に生ずる変形のモデル図、第４
図は温度差ΔＴと急峻度δとの関係を示すグラ
フ、第５図ａ，ｂは本発明の適用対象である冷却
ロールａは配置図、ｂは冷却ロールの温度と時間
との関係を示すグラフである。
図面中、１は冷却ロール、δは急峻度、ΔＴは
温度差である。
Figure 1 a, b is an explanatory diagram of a conventional cooling roll, Figure 2 a, b, c is an explanatory diagram of the location of the cooling roll, Figure 3 is a model diagram of the deformation that occurs in a steel plate, Figure 4
The figure is a graph showing the relationship between the temperature difference ΔT and the steepness δ, Figures 5a and 5b show the arrangement of the cooling roll a to which the present invention is applied, and b shows the relationship between the temperature of the cooling roll and time. It is a graph. In the drawings, 1 is the cooling roll, δ is the steepness, and ΔT is the temperature difference.
Claims (1)
許容値となるときの前記冷却ロールの温度とこの
ときの接触開始位置における鋼板の平均温度との
温度差を求め、当該平均温度における鋼板の縦弾
性係数と線膨張係数と前記温度差との積で得られ
る見掛け上の熱応力と当該平均温度における鋼板
の降伏点との比を予め求めておき、実際に冷却ロ
ールに導入された場合の前記平均温度における鋼
板の降伏点よりも当該平均温度における鋼板の見
掛け上の熱応力と前記比との積が小さくなるよう
に冷却ロールの温度を制御するようにしたことを
特徴とする鋼板の冷却方法。1. Find the temperature difference between the temperature of the cooling roll when the permanent strain of the steel plate after passing through the cooling roll reaches the maximum allowable value and the average temperature of the steel plate at the contact start position at this time, and calculate the longitudinal elasticity of the steel plate at that average temperature. The ratio of the apparent thermal stress obtained by multiplying the coefficient, the coefficient of linear expansion, and the temperature difference to the yield point of the steel plate at the average temperature is determined in advance, and the ratio of the yield point of the steel plate at the average temperature is determined in advance, and the ratio of the yield point of the steel plate at the average temperature is determined in advance. A method for cooling a steel plate, characterized in that the temperature of the cooling roll is controlled so that the product of the ratio and the apparent thermal stress of the steel plate at the average temperature is smaller than the yield point of the steel plate at that temperature.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9748280A JPS5723036A (en) | 1980-07-18 | 1980-07-18 | Method for cooling steel plate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9748280A JPS5723036A (en) | 1980-07-18 | 1980-07-18 | Method for cooling steel plate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5723036A JPS5723036A (en) | 1982-02-06 |
| JPS6259170B2 true JPS6259170B2 (en) | 1987-12-09 |
Family
ID=14193486
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9748280A Granted JPS5723036A (en) | 1980-07-18 | 1980-07-18 | Method for cooling steel plate |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5723036A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS599130A (en) * | 1982-07-08 | 1984-01-18 | Kawasaki Steel Corp | Roll cooling method of steel strip |
| JPS5920429A (en) * | 1982-07-26 | 1984-02-02 | Nippon Kokan Kk <Nkk> | Cooling method of steel strip in continuous annealing furnace |
| JPS59143028A (en) * | 1983-02-03 | 1984-08-16 | Nippon Steel Corp | Cooler for metallic strip in continuous heat treating furnace |
| JPS60169525A (en) * | 1984-02-15 | 1985-09-03 | Mitsubishi Heavy Ind Ltd | Method for cooling steel strip in cooling zone of continuous annealing furnace |
-
1980
- 1980-07-18 JP JP9748280A patent/JPS5723036A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5723036A (en) | 1982-02-06 |
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