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WO2025126573A1 - Method for controlling steel sheet manufacturing facility and steel sheet manufacturing facility - Google Patents

Method for controlling steel sheet manufacturing facility and steel sheet manufacturing facility Download PDF

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Publication number
WO2025126573A1
WO2025126573A1 PCT/JP2024/029234 JP2024029234W WO2025126573A1 WO 2025126573 A1 WO2025126573 A1 WO 2025126573A1 JP 2024029234 W JP2024029234 W JP 2024029234W WO 2025126573 A1 WO2025126573 A1 WO 2025126573A1
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Prior art keywords
steel sheet
zone
heat treatment
mechanical property
cooling
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French (fr)
Japanese (ja)
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顕一 大須賀
玄太郎 武田
由康 川崎
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JFE Steel Corp
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JFE Steel Corp
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    • 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
    • C21D11/00—Process control or regulation for heat treatments
    • 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

Definitions

  • the present invention relates to a method for manufacturing high-strength steel plates used in automotive structural materials, etc., and in particular, makes it possible to reduce the introduction costs of manufacturing equipment while suppressing the occurrence of material variations.
  • the continuously cast slab is subjected to extensive processing by hot rolling and cold rolling until it reaches the final plate thickness.
  • the cold-worked structure is restored, recrystallized, and the grains grow, and the transformation structure is controlled.
  • the mechanical properties of the product are adjusted by the cooling process after annealing.
  • automobile body structural members are generally manufactured by press processing, and products that combine high strength and high workability are required.
  • zinc plating is often performed as a material for automobile parts in order to provide rust resistance.
  • alloyed hot-dip galvanized steel sheets in which zinc and iron are alloyed by heating after plating, are widely used.
  • Patent Document 1 discloses a method in which the material is rapidly cooled to below the martensite transformation temperature in the cooling zone on the exit side of the annealing furnace, then reheated and tempered.
  • Patent Document 2 discloses a method of obtaining the desired properties of the plating layer and the mechanical properties of the steel sheet by providing a tempering process in which, without transforming the steel strip into martensite in the cooling zone in the annealing furnace, alloying is performed in a state in which the austenite phase remains, and then the martensite structure is obtained by rapid cooling.
  • a tempering process in which, without transforming the steel strip into martensite in the cooling zone in the annealing furnace, alloying is performed in a state in which the austenite phase remains, and then the martensite structure is obtained by rapid cooling.
  • coils are joined together and heat treated continuously, so that it is necessary to change the operating conditions when the plate thickness, components, and target mechanical properties change.
  • Patent Document 2 does not disclose a method for dealing with such a problem.
  • Patent Document 3 a technology for controlling the material quality of a steel sheet by a material quality prediction model using the operation parameters of a continuous annealing facility and transformation rate information of the steel sheet acquired downstream of the continuous annealing facility as input data is disclosed in Patent Document 3.
  • This technology claims that material quality fluctuations can be suppressed by controlling the operation conditions of the manufacturing equipment downstream of the position where transformation rate information of the steel sheet is acquired, called the material quality control zone.
  • the material quality control zone the operation conditions of the manufacturing equipment downstream of the position where transformation rate information of the steel sheet is acquired.
  • the present invention has been made in consideration of the above problems, and aims to provide a method for controlling steel plate manufacturing equipment and steel plate manufacturing equipment that makes it possible to precisely obtain the desired mechanical properties for the manufactured steel plate.
  • the inventors conducted extensive research to solve these problems, and came to the following conclusion.
  • the mechanical properties, particularly the elongation value, when the following material passes through the steel sheet are predicted based on the heating temperature in the tempering zone of the preceding material before and after the joint of the steel strip where the target mechanical properties change.
  • the inventors came up with the idea of changing the heat treatment conditions of the continuous annealing facility, particularly the steel sheet heating temperature in the soaking zone, in real time before the following material passes through in order to reduce the difference between the predicted value and the target elongation value. Even if there is a delay in changing the heat treatment conditions in the tempering zone, the heat treatment conditions in the soaking zone can be changed to match the heat treatment conditions, thereby making it possible to obtain the target mechanical properties over the entire length.
  • a continuous annealing facility for steel sheets having a heating zone, a soaking zone, and a cooling zone in this order in a steel sheet transport direction;
  • a post-annealing heat treatment facility having at least a rapid cooling zone and a tempering zone in this order downstream of the cooling zone in the steel sheet transport direction;
  • Temperature measuring devices for the steel sheet are installed at least in the soaking zone and the tempering zone;
  • a method for controlling a steel sheet heating temperature in a continuous annealing facility in a steel sheet manufacturing facility comprising: A mechanical property prediction step of predicting mechanical property values including an elongation value and a hole expansion ratio of the steel sheet based on the steel sheet heating temperature in the tempering zone measured by the temperature measuring device; a heat treatment condition calculation step of correcting the mechanical property values predicted in the mechanical property prediction step to target mechanical property values of the steel sheet, and determining heat treatment conditions based on the corrected mechanical property values; a heat treatment condition control step of controlling
  • the present invention makes it possible to precisely obtain the desired mechanical properties for the manufactured steel plate.
  • the steel sheet manufacturing equipment 1 of the present invention may have a management device 30, and the management device 30 has a mechanical property prediction unit 31 that predicts mechanical property values including an elongation value and a hole expansion ratio of the steel sheet S based on the steel sheet heating temperature in the tempering zone 16 measured by the temperature measurement device 20, a heat treatment condition calculation unit 32 that corrects the mechanical property values predicted by the mechanical property prediction unit 31 to target mechanical property values of the steel sheet S (target elongation value, target hole expansion ratio, etc.) and determines heat treatment conditions based on the corrected mechanical property values, and a heat treatment condition control unit 33 that controls the steel sheet heating temperature in at least the soaking zone 8 of each facility constituting the continuous annealing equipment 5 based on the heat treatment conditions determined by the heat treatment condition calculation unit 32.
  • a mechanical property prediction unit 31 that predicts mechanical property values including an elongation value and a hole expansion ratio of the steel sheet S based on the steel sheet heating temperature in the tempering zone 16 measured by the temperature measurement device 20
  • Rapid cooling zone 15 When the steel sheet S is subjected to a plating treatment (when the post-annealing heat treatment equipment 11 is used as a steel sheet plating equipment), a rapid cooling zone 15 is provided following the plating alloying zone 13 or the holding zone 14 in order to transform the untransformed austenite phase into a martensite structure after the plating alloying reaction is completed. When the steel sheet S is not subjected to a plating treatment, the rapid cooling zone 15 may be provided downstream of the cooling zone 10 in the steel sheet transport direction X.
  • the heat retention device 18 is preferably a radiant heating method from the heater body and furnace wall using an electric heater from the viewpoint of temperature uniformity within the device, but is not particularly limited. In a steady state, the furnace temperature may be controlled to be approximately the same as the target tempering temperature.
  • the cooling device 19 is preferably a mist cooling method from the viewpoint of cooling efficiency, and a gas jet device is also preferably installed to remove moisture attached to the surface at the same time as cooling, but is not particularly limited as long as it can be adjusted to the target cooling rate.
  • the transformation rate measuring device 21 may be a magnetic detector, i.e., a device for measuring the magnetic transformation rate of the steel sheet S (steel strip), and can measure the austenite fraction as a magnetic transformation rate measuring device composed of a driving coil that generates a magnetic field and a detection coil that measures the magnetic field that has passed through the steel sheet S.
  • a method applying an X-ray diffraction method may be adopted.
  • the management device 30 determines that the manufacturing conditions need to be changed.
  • the mechanical property prediction unit 31 predicts the mechanical property values of the steel sheet S (successor material) based on the operating conditions (steel sheet heating temperature) in the tempering zone (reheating zone) 16. Examples of the mechanical property values include elongation value and hole expansion ratio.
  • Other operational conditions input to the mechanical property prediction unit 31 include the operational conditions of the equipment downstream of the soaking zone 8, and the mechanical properties are predicted when the subsequent material has completed the process up to the tempering zone (reheating zone) 16 under these operational conditions.
  • the austenite fraction result measured by the transformation rate measurement device 21 is further added to the operational conditions, and the mechanical property values are predicted based on this austenite fraction and the operational conditions, thereby improving the prediction accuracy of the mechanical property values. Since temperature measurement alone results in indirect prediction of the structure, by further directly measuring the austenite fraction, the prediction accuracy of the mechanical properties after the heat treatment process is improved.
  • the method of predicting mechanical properties performed by the mechanical property prediction unit 31 with regard to elongation value and hole expansion ratio, for example, a method using an empirical formula calculated by performing regression analysis based on the results of heat treatment experiments, or an elongation value prediction database constructed using a data science method based on operating conditions and material measurement results, etc., can be considered, but is not particularly limited.
  • a regression analysis method based on the experimental results of heat treatment of each steel sheet can be used.
  • heat treatment simulating an actual machine is performed offline or experimentally, and in this case, regression analysis is performed based on the results of the test method of JIS Z2241 (2011) for elongation value, and regression analysis is performed based on the results of the test method of JIS Z2256 (2010) for hole expansion ratio to predict elongation value and hole expansion ratio.
  • the mechanical property prediction unit 31 can record data in a memory unit 34 having the above-mentioned elongation value prediction database, and can predict the elongation value, etc. of the steel sheet S based on the data.
  • Heat treatment condition calculation unit 32, heat treatment condition calculation step S4 In the heat treatment condition calculation step S4, the mechanical property values of the steel sheet S (successor material) predicted by the mechanical property prediction unit 31 in the mechanical property prediction step S3 are corrected to target mechanical property values, and the heat treatment conditions in the continuous annealing equipment 5 are calculated based on the corrected mechanical property values.
  • the term "correction” used here refers to changing the mechanical characteristic values for calculating the heat treatment conditions from predicted mechanical characteristic values to preset target mechanical characteristic values.
  • the heat treatment condition calculation unit 32 determines that the target mechanical characteristic values can be corrected by simply changing the steel sheet heating conditions in the soaking zone 8 (step S5), it calculates and determines the conditions of the steel sheet heating temperature in the soaking zone 8 (step S6a).
  • the heat treatment condition computing device 32 computes the steel sheet cooling conditions in the cooling zone 10 in addition to the heating temperature in the soaking zone 8 (step S6b).
  • a method for determining the heat treatment conditions for example, an empirical formula calculated by performing regression analysis based on the results of an experiment, or a method using a heat treatment condition database constructed by a data science method based on the operating conditions and the material measurement results can be considered, but is not particularly limited.
  • a regression analysis method based on the experimental results of the heat treatment of each steel sheet can be used.
  • a heat treatment simulating an actual machine is performed offline or in an experiment, and a regression analysis is performed based on the results to predict the elongation value, hole expansion ratio, etc.
  • the cooling conditions of the steel sheet in the cooling zone 10 are not particularly limited, but include, for example, a cooling stop temperature and a cooling rate in the cooling zone 10.
  • the cooling stop temperature and the cooling rate can be obtained by measuring with a thermometer installed in the cooling zone 10.
  • the heat treatment condition calculation unit 32 can record data in the memory unit 34 having the above-mentioned heat treatment condition database, and can calculate and determine the heat treatment conditions for the steel sheet S based on the data.
  • the heat treatment condition control unit 33 controls the steel sheet heating temperature in the soaking zone 8, or further the steel sheet cooling conditions in the cooling zone 10, based on the heat treatment conditions determined by the heat treatment condition calculation unit 32.
  • the mechanical properties (elongation value, hole expansion ratio) of the steel sheet S (trailing zone) can be controlled with greater precision.
  • the management device 30 judges whether the heat treatment conditions determined based on the steel sheet heating temperature measured in the tempering zone (reheat zone) 16 satisfy the target heat treatment conditions of the following material (step S8). If it is judged that the target heat treatment conditions of the following material are satisfied, the management device 30 stops the control in the above-mentioned mechanical property prediction step S3, heat treatment condition calculation step S4, and heat treatment condition control step S7, and adjusts the heat treatment conditions (steady heat treatment conditions) other than the above target heat treatment conditions for the following material (transition to a steady state).
  • the steady state here refers to a state in which the heat treatment conditions, including the target heat treatment conditions, have reached the desired conditions. This ends the process of controlling the steel sheet manufacturing equipment in the present invention. On the other hand, if it is judged that the target heat treatment conditions of the following material are not satisfied, mechanical property prediction is performed again (step S3).
  • the mechanical property prediction unit 31 By performing the control described with reference to FIG. 2 , even if there is a concern that a control delay will occur and the operating conditions in the tempering zone 16 will differ from the target tempering conditions for the subsequent material, making it possible to obtain the desired mechanical property values, information on the steel sheet heating temperature can be input to the mechanical property prediction unit 31, the heat treatment conditions in the continuous annealing equipment 5 required for correcting the values to the target mechanical property values can be calculated by the heat treatment condition calculation unit 32, and the heat treatment conditions in the soaking zone 8 and/or cooling zone 10 can be controlled by the heat treatment condition control unit 33, thereby canceling out the control delay in the tempering zone 16. In this way, the deviation of the mechanical properties of the resulting steel plate from the desired mechanical properties can be reduced, and the target mechanical properties can be stably obtained in the longitudinal direction compared to conventional steel plate manufacturing equipment.
  • Thin steel sheets were manufactured using the steel sheet manufacturing equipment according to the embodiment of the present invention described above.
  • three types of products with strength levels of 780 MPa, 980 MPa, and 1180 MPa were manufactured in succession. Five pieces of each strength were passed through in succession, and 10 sets of 15 pieces of the three types were manufactured in one set, for a total of 150 pieces in each example.
  • the plate thickness was in the range of 1.0 to 2.0 mm, and the manufacturing order was determined so that the plate thickness was approximately constant within the set, and the sets in which the plate thickness gradually changed were connected to manufacture.
  • products with the same strength included in the same set were all manufactured using slabs cast in different lots in a continuous casting machine. More specifically, although within the manufacturing control range, the chemical compositions of each slab vary and the transformation behavior is not uniform.
  • Each slab was hot-rolled, pickled, annealed and cold-rolled as required, and then heat-treated using a conventional annealing facility or the annealing facility of the present invention, followed by cooling, plating and other post-treatments.
  • the measurement results of samples taken 10 m from the coil tip of the final product were used as representative values to examine the characteristic variation between products of the same strength.
  • samples for analysis were taken every 10 m within a range of 100 m before and after the connection point, and the area where the mechanical properties did not meet the shipping standard was examined, and the ratio of the shippable length to the original coil length was calculated as the yield of the connection. A connection yield of 90% or more was considered to be acceptable.
  • the tensile test specimen was JIS No. 5, and the tensile test was performed in accordance with JIS Z2241 (2011).
  • the required strength ranges are 780 MPa or more, 980 MPa or more, and 1180 MPa or more, respectively, and the ductility is 17% or more, 15% or more, and 12% or more.
  • the hole expansion test was performed in accordance with JIS Z2256 (2010). The required hole expansion ratios are 65% or more, 50% or more, and 40% or more for the strengths of 780 MPa class, 980 MPa class, and 1180 MPa class, respectively.
  • the operating conditions of the annealing furnace were controlled so that the steel plate temperature was within the specified range for each product.
  • the line speed was in the range of 60 to 120 mpm, and the change in steel plate temperature due to plate thickness was controlled.
  • the steel plate temperature at the exit of the heating zone was kept in the range of 600 to 700°C, and the annealing temperature was in the range of 750 to 870°C.
  • the furnace temperature in the soaking zone was controlled so that the steel plate temperature at the exit was the target value. After cooling, hot-dip galvanizing, alloying treatment, etc., multiple material test pieces were taken from the final product to investigate the variation in mechanical properties.
  • Table 1 shows the production results under each production condition.
  • Comparative Example 1 is an example in which a product was manufactured from the above-mentioned material by using a conventional CGL described in Cited Document 1, which is composed of a preheating zone, a heating zone, a soaking zone, a cooling zone, a plating zone, a plating alloying zone, and a final cooling zone.
  • Comparative Example 2 is an example in which a tempering zone was provided after the plating alloying zone in comparison with Comparative Example 1.
  • Comparative Example 3 is an example in which an induction heating device is provided on the exit side of the annealing furnace of Comparative Example 2 (after the cooling zone). In these comparative examples, even when a tempering zone (reheating zone) was used, control of the continuous annealing equipment based on the steel sheet heating temperature in the tempering zone was "not performed.”
  • Example 1 shows the results of manufacturing a product from the above-mentioned material using the method for controlling steel sheet manufacturing equipment according to the present invention.
  • Example 3 is an example in which a transformation rate measuring device is installed downstream of the induction heating device of Example 1.
  • control of the continuous annealing equipment based on the steel sheet heating temperature in the tempering zone was "implemented.”
  • the TS variation was further improved by controlling the annealing temperature based on the austenite fraction measured by the transformation rate measuring device.

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  • 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)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Control Of Heat Treatment Processes (AREA)

Abstract

Provided is a technique that makes it possible to accurately obtain desired mechanical characteristics of a steel sheet to be manufactured.　This method for controlling a steel sheet manufacturing facility includes: a mechanical characteristic prediction step (S3) for predicting mechanical characteristic values including an elongation value and a hole expansion ratio of a steel sheet on the basis of a steel sheet heating temperature in a tempering zone (16) measured by a temperature measuring device (20); a heat treatment condition calculation step (S4) for correcting the mechanical characteristic values predicted in the mechanical characteristic prediction step (S3) to target mechanical characteristic values of the steel sheet (S), and determining a heat treatment condition on the basis of the corrected mechanical characteristic values; and a heat treatment condition control step (S8) for controlling the steel sheet heating temperature in at least a soaking zone (8) of a continuous annealing facility on the basis of the heat treatment condition determined in the heat treatment condition calculation step (S4).

Description

鋼板製造設備の制御方法および鋼板製造設備METHOD FOR CONTROLLING STEEL PLATE MANUFACTURING EQUIPMENT AND STEEL PLATE MANUFACTURING EQUIPMENT

　本発明は、自動車用構造材などに用いられる高強度鋼板を製造する方法に関し、特に、材質ばらつきの発生を抑制しつつ、製造設備の導入コスト低減を可能にするものである。 The present invention relates to a method for manufacturing high-strength steel plates used in automotive structural materials, etc., and in particular, makes it possible to reduce the introduction costs of manufacturing equipment while suppressing the occurrence of material variations.

　自動車用薄鋼板の製造では、連続鋳造されたスラブは最終板厚に達するまで熱間圧延、冷間圧延によって大きな加工を付与される。続いて行われる焼鈍処理において、冷間加工組織の回復、再結晶および粒成長をさせ、さらには、変態組織制御を行い、焼鈍後の冷却処理と合わせて製品の機械特性を調整している。近年では、自動車の軽量化と衝突安全性を両立させるために、より高強度な鋼板が求められている。一方で、自動車の車体構造部材はプレス加工で製造されるのが一般的であり、高強度と高加工性を両立した製品が求められている。また、自動車用部品の素材としては、防錆性を持たせる目的で亜鉛めっき処理を行うことが多い。特に、プレス加工性の観点から、めっき処理後の加熱により亜鉛と鉄を合金化させた、合金化溶融亜鉛めっき鋼板が広く採用されている。 In the manufacture of thin steel sheets for automobiles, the continuously cast slab is subjected to extensive processing by hot rolling and cold rolling until it reaches the final plate thickness. In the subsequent annealing process, the cold-worked structure is restored, recrystallized, and the grains grow, and the transformation structure is controlled. In addition, the mechanical properties of the product are adjusted by the cooling process after annealing. In recent years, there is a demand for higher strength steel sheets to balance the weight reduction and collision safety of automobiles. On the other hand, automobile body structural members are generally manufactured by press processing, and products that combine high strength and high workability are required. In addition, zinc plating is often performed as a material for automobile parts in order to provide rust resistance. In particular, from the viewpoint of press workability, alloyed hot-dip galvanized steel sheets, in which zinc and iron are alloyed by heating after plating, are widely used.

　高強度を実現する方法としては、焼鈍で生じたオーステナイト相を急冷することで得られるマルテンサイト組織の活用が挙げられる。しかしながら、冷却したままのマルテンサイト組織は脆く扱いづらいため、再度加熱する焼き戻し処理によって靭性を高めることができる。そこで、焼鈍炉出側冷却帯でマルテンサイト変態温度以下まで急冷した後に再加熱を行い、焼き戻し処理する方法が特許文献１に開示されている。 One method for achieving high strength is to utilize a martensite structure obtained by rapidly cooling the austenite phase created by annealing. However, as the martensite structure is brittle and difficult to handle when cooled, toughness can be increased by reheating it for tempering. Patent Document 1 discloses a method in which the material is rapidly cooled to below the martensite transformation temperature in the cooling zone on the exit side of the annealing furnace, then reheated and tempered.

特許第５４０２００７号公報Patent No. 5402007 特許第５９６７３１８号公報Patent No. 5967318 特開２０２２－０２４３４０号公報JP 2022-024340 A

　特許文献１で開示された方法のように、焼戻し後に亜鉛めっき処理と合金化処理を行う場合、一般に合金化温度は焼戻し温度よりも高温であるため、合金化加熱によって過度に焼戻され、必要な強度が得られない。そこで、焼鈍炉の中の冷却帯において、鋼帯をマルテンサイト変態させずに、オーステナイト相が残留した状態で合金化処理を行い、急速冷却によってマルテンサイト組織を得た後に、焼戻しを行う焼戻し工程を備えることで、目的となるめっき層の特性と鋼板の機械特性を得る方法が、特許文献２に開示されている。
しかしながら、実際の連続焼鈍工程では、コイル同士をつなぎ合わせて連続的に熱処理を行うため、板厚や成分、目標となる機械特性が切り替わる際には操業条件を変更する必要がある。このような、操業条件の変更が設備に反映されない場合、目標となる機械特性が異なるコイルのつなぎ目の前後では、最適な条件で製造できない部分が発生し、歩留まり低下を招く。この点、特許文献２ではこのような問題への対処方法は明らかにされていない。 When performing galvanizing and alloying treatment after tempering as in the method disclosed in Patent Document 1, the alloying temperature is generally higher than the tempering temperature, so that excessive tempering occurs due to alloying heating and the required strength cannot be obtained. Therefore, Patent Document 2 discloses a method of obtaining the desired properties of the plating layer and the mechanical properties of the steel sheet by providing a tempering process in which, without transforming the steel strip into martensite in the cooling zone in the annealing furnace, alloying is performed in a state in which the austenite phase remains, and then the martensite structure is obtained by rapid cooling.
However, in an actual continuous annealing process, coils are joined together and heat treated continuously, so that it is necessary to change the operating conditions when the plate thickness, components, and target mechanical properties change. If such changes in operating conditions are not reflected in the equipment, there will be parts that cannot be manufactured under optimal conditions before and after the joints of coils with different target mechanical properties, resulting in a decrease in yield. In this regard, Patent Document 2 does not disclose a method for dealing with such a problem.

　こうした長手方向の品質安定性向上について、連続焼鈍設備の操業パラメータと、連続焼鈍設備の下流で取得される鋼板の変態率情報とを入力データとした材質予測モデルによって、鋼板の材質を制御する技術が特許文献３に開示されている。この技術では、材質制御帯と呼ばれる鋼板の変態率情報を取得した位置よりも下流側の製造装置の操業条件を制御することで材質変動を抑制できるとしている。しかしながら、材質制御帯への制御遅れが生じた場合、先端部においては目標となる機械特性が得られないが、この課題に対する解決策は提示されていないため、効果は不十分である。
　このように、従来の技術は、製造される鋼板が所望の機械特性を有するようにする技術としては、まだ十分とは言えなかった。 Regarding such improvement of quality stability in the longitudinal direction, a technology for controlling the material quality of a steel sheet by a material quality prediction model using the operation parameters of a continuous annealing facility and transformation rate information of the steel sheet acquired downstream of the continuous annealing facility as input data is disclosed in Patent Document 3. This technology claims that material quality fluctuations can be suppressed by controlling the operation conditions of the manufacturing equipment downstream of the position where transformation rate information of the steel sheet is acquired, called the material quality control zone. However, if there is a control delay in the material quality control zone, the target mechanical properties cannot be obtained at the tip, and since no solution to this problem has been presented, the effect is insufficient.
As described above, the conventional techniques are still not sufficient to ensure that the steel sheets produced have the desired mechanical properties.

　そこで、本発明は、上記の問題を鑑みなされたものであり、製造される鋼板について、所望の機械特性を精度良く得ることを可能にする鋼板製造設備の制御方法および鋼板製造設備を提供することを目的とする。 The present invention has been made in consideration of the above problems, and aims to provide a method for controlling steel plate manufacturing equipment and steel plate manufacturing equipment that makes it possible to precisely obtain the desired mechanical properties for the manufactured steel plate.

　本発明者らは、このような問題を解決すべく鋭意検討を重ねた結果、以下のような知見を得た。本発明の対象となる図１に示すような鋼板製造設備において、目標となる機械特性が切り替わる鋼帯のつなぎ目前後で、先行材の焼戻し帯での加熱温度を元に、後行材が通板した際の機械特性、特に伸び値を予測し、その予測値と目標の伸び値との差を低減するように、後行材通過前に連続焼鈍設備の熱処理条件、特に均熱帯での鋼板加熱温度をリアルタイムで変更することで、焼戻し帯での熱処理条件の変更が遅れた場合でも、その熱処理条件に合わせて均熱帯での熱処理条件を変更することで、目標となる機械特性が全長にわたって得られることを着想した。 The inventors conducted extensive research to solve these problems, and came to the following conclusion. In a steel sheet manufacturing facility as shown in FIG. 1, which is the subject of the present invention, the mechanical properties, particularly the elongation value, when the following material passes through the steel sheet are predicted based on the heating temperature in the tempering zone of the preceding material before and after the joint of the steel strip where the target mechanical properties change. The inventors came up with the idea of changing the heat treatment conditions of the continuous annealing facility, particularly the steel sheet heating temperature in the soaking zone, in real time before the following material passes through in order to reduce the difference between the predicted value and the target elongation value. Even if there is a delay in changing the heat treatment conditions in the tempering zone, the heat treatment conditions in the soaking zone can be changed to match the heat treatment conditions, thereby making it possible to obtain the target mechanical properties over the entire length.

　本発明は、上記のような知見と着想に基づいてなされたものであり、以下の特徴を有している。
［１］鋼板搬送方向に、加熱帯と、均熱帯と、冷却帯と、をこの順で有する鋼板の連続焼鈍設備と、
前記冷却帯の前記鋼板搬送方向の下流に、少なくとも急速冷却帯と、焼戻し帯と、をこの順で有する焼鈍後熱処理設備と、
少なくとも前記均熱帯と前記焼戻し帯に設置される前記鋼板の温度測定装置と、
を備える鋼板製造設備における前記連続焼鈍設備での鋼板加熱温度の制御方法であって、
前記温度測定装置で測定した前記焼戻し帯での鋼板加熱温度に基づいて、前記鋼板の伸び値および穴広げ率を含む機械特性値を予測する機械特性予測ステップと、
該機械特性予測ステップで予測した前記機械特性値を前記鋼板の目標機械特性値に補正し、補正された前記機械特性値に基づいて熱処理条件を決定する熱処理条件演算ステップと、
該熱処理条件演算ステップで決定した熱処理条件に基づいて、前記連続焼鈍設備のうち、少なくとも前記均熱帯での鋼板加熱温度を制御する熱処理条件制御ステップと、
を含む、鋼板製造設備の制御方法。
［２］前記熱処理条件制御ステップにおいて、前記熱処理条件演算ステップで決定した熱処理条件に基づいて、前記均熱帯での鋼板加熱温度と、前記冷却帯での鋼板冷却条件とを制御する、前記［１］に記載の鋼板製造設備の制御方法。
［３］前記鋼板製造設備において、前記鋼板搬送方向に、前記均熱帯出側から前記焼戻し帯出側までのうちの少なくとも１箇所で前記鋼板のオーステナイト分率を測定する変態率測定装置をさらに備え、
前記機械特性予測ステップでは、
前記温度測定装置で測定した前記焼戻し帯での鋼板加熱温度と、前記変態率測定装置で測定したオーステナイト分率とに基づいて、前記鋼板の機械特性値を予測する、前記［１］または［２］に記載の鋼板製造設備の制御方法。
［４］鋼板搬送方向に、加熱帯と、均熱帯と、冷却帯と、をこの順で有する鋼板の連続焼鈍設備と、
前記冷却帯の前記鋼板搬送方向の下流に、少なくとも急速冷却帯と、焼戻し帯と、をこの順で有する焼鈍後熱処理設備と、
少なくとも前記均熱帯と前記焼戻し帯に設置される前記鋼板の温度測定装置と、
を備える鋼板製造設備であって、
前記温度測定装置で測定した前記焼戻し帯での鋼板加熱温度に基づいて、前記鋼板の伸び値および穴広げ率を含む機械特性値を予測する機械特性予測部と、
該機械特性予測部で予測した前記機械特性値を前記鋼板の目標機械特性値に補正し、補正された前記機械特性値に基づいて熱処理条件を決定する熱処理条件演算部と、
該熱処理条件演算部で決定した熱処理条件に基づいて、前記連続焼鈍設備のうち、少なくとも前記均熱帯での鋼板加熱温度を制御する熱処理条件制御部と、
をさらに備える、鋼板製造設備。
［５］前記熱処理条件制御部において、前記熱処理条件演算部で決定した熱処理条件に基づいて、前記均熱帯での鋼板加熱温度と、前記冷却帯での鋼板冷却条件とを制御する、前記［４］に記載の鋼板製造設備。
［６］前記鋼板搬送方向に、前記均熱帯出側から前記焼戻し帯出側までのうち少なくとも１箇所で前記鋼板のオーステナイト分率を測定する変態率測定装置を備え、
前記機械特性予測部では、
前記温度測定装置で測定した前記焼戻し帯での鋼板加熱温度と、前記変態率測定装置で測定したオーステナイト分率とに基づいて、前記鋼板の機械特性値を予測する、前記［４］または［５］に記載の鋼板製造設備。 The present invention has been made based on the above findings and ideas, and has the following characteristics.
[1] A continuous annealing facility for steel sheets having a heating zone, a soaking zone, and a cooling zone in this order in a steel sheet transport direction;
A post-annealing heat treatment facility having at least a rapid cooling zone and a tempering zone in this order downstream of the cooling zone in the steel sheet transport direction;
Temperature measuring devices for the steel sheet are installed at least in the soaking zone and the tempering zone;
A method for controlling a steel sheet heating temperature in a continuous annealing facility in a steel sheet manufacturing facility comprising:
A mechanical property prediction step of predicting mechanical property values including an elongation value and a hole expansion ratio of the steel sheet based on the steel sheet heating temperature in the tempering zone measured by the temperature measuring device;
a heat treatment condition calculation step of correcting the mechanical property values predicted in the mechanical property prediction step to target mechanical property values of the steel sheet, and determining heat treatment conditions based on the corrected mechanical property values;
a heat treatment condition control step of controlling a steel sheet heating temperature in at least the soaking zone in the continuous annealing facility based on the heat treatment conditions determined in the heat treatment condition calculation step;
A method for controlling a steel plate manufacturing facility, comprising:
[2] The control method for steel sheet manufacturing equipment according to [1], wherein in the heat treatment condition control step, a steel sheet heating temperature in the soaking zone and a steel sheet cooling condition in the cooling zone are controlled based on the heat treatment conditions determined in the heat treatment condition calculation step.
[3] The steel sheet manufacturing facility further includes a transformation rate measuring device for measuring an austenite fraction of the steel sheet at at least one location from the soaking zone exit side to the tempering zone exit side in the steel sheet transport direction,
In the mechanical property prediction step,
The method for controlling steel sheet manufacturing equipment according to claim 1 or 2, further comprising predicting mechanical property values of the steel sheet based on the steel sheet heating temperature in the tempering zone measured by the temperature measuring device and the austenite fraction measured by the transformation ratio measuring device.
[4] A continuous annealing facility for steel sheets having a heating zone, a soaking zone, and a cooling zone in this order in a steel sheet transport direction;
A post-annealing heat treatment facility having at least a rapid cooling zone and a tempering zone in this order downstream of the cooling zone in the steel sheet transport direction;
Temperature measuring devices for the steel sheet are installed at least in the soaking zone and the tempering zone;
A steel sheet manufacturing facility comprising:
A mechanical property prediction unit that predicts mechanical property values including an elongation value and a hole expansion ratio of the steel sheet based on the steel sheet heating temperature in the tempering zone measured by the temperature measuring device;
a heat treatment condition calculation unit that corrects the mechanical property values predicted by the mechanical property prediction unit to target mechanical property values of the steel sheet and determines heat treatment conditions based on the corrected mechanical property values; and
a heat treatment condition control unit that controls a steel sheet heating temperature in at least the soaking zone in the continuous annealing facility based on the heat treatment conditions determined by the heat treatment condition calculation unit;
The steel plate manufacturing facility further comprises:
[5] The steel sheet manufacturing equipment according to [4], wherein the heat treatment condition control unit controls the steel sheet heating temperature in the soaking zone and the steel sheet cooling conditions in the cooling zone based on the heat treatment conditions determined by the heat treatment condition calculation unit.
[6] A transformation rate measuring device is provided in the steel sheet transport direction, which measures an austenite fraction of the steel sheet at at least one location from the soaking zone exit side to the tempering zone exit side,
In the mechanical property prediction unit,
The steel plate manufacturing facility according to claim 4 or 5, wherein mechanical property values of the steel plate are predicted based on the steel plate heating temperature in the tempering zone measured by the temperature measuring device and the austenite fraction measured by the transformation ratio measuring device.

　本発明によれば、製造される鋼板について、所望の機械特性を精度良く得ることを可能にする。 The present invention makes it possible to precisely obtain the desired mechanical properties for the manufactured steel plate.

本発明における鋼板製造設備の構成を説明するための図である。FIG. 1 is a diagram for explaining a configuration of a steel sheet manufacturing facility according to the present invention. 本発明における鋼板製造設備の制御方法を説明するためのフロー図である。FIG. 2 is a flow chart for explaining a method for controlling a steel sheet manufacturing facility according to the present invention.

　＜設備構成＞
　図１は、本発明の実施形態である鋼板製造設備１の概略図である。図１に示すように、前工程でコイル状に巻き取られた鋼板Ｓは、ペイオフリール２で巻き戻され、鋼板搬送方向（図１中、符号Ｘ参照）に沿ってルーパー４に進入する。ルーパー４は、鋼板Ｓ（コイル）同士をウエルダー３でつなぎ合わせる際に鋼板Ｓを連続的に通板させ続けるために、鋼板の余長を確保しておく設備になる。ルーパー４通過後は、鋼板Ｓは連続焼鈍設備５へと進入する。連続焼鈍設備５の入り口側には加熱帯７が設置される。あるいはさらに、加熱帯７の前には、加熱帯７で発生する燃焼排ガスを利用した予熱帯６を設置してもよい。
連続焼鈍設備５は、加熱帯７に続いて、均熱帯８、冷却帯１０（第１冷却帯１０Ａおよび第２冷却帯１０Ｂ）がこの順で構成されている。冷却帯１０は、求められる機械特性に応じて必要とされる冷却量と通板速度とに合わせて第１冷却帯１０Ａのみの構成としてもよいし、図１に示すように、第１冷却帯１０Ａおよび第２冷却帯１０Ｂを備えた２段構成としてもよい。 <Equipment configuration>
FIG. 1 is a schematic diagram of a steel sheet manufacturing facility 1 according to an embodiment of the present invention. As shown in FIG. 1, a steel sheet S wound into a coil in a previous process is unwound by a payoff reel 2 and enters a looper 4 along the steel sheet conveying direction (see symbol X in FIG. 1). The looper 4 is a facility for securing the surplus length of the steel sheet in order to continuously pass the steel sheet S when the steel sheets S (coils) are joined together by a welder 3. After passing through the looper 4, the steel sheet S enters a continuous annealing facility 5. A heating zone 7 is installed at the entrance side of the continuous annealing facility 5. Alternatively, a preheating zone 6 utilizing the combustion exhaust gas generated in the heating zone 7 may be installed before the heating zone 7.
The continuous annealing equipment 5 is configured with a heating zone 7, a soaking zone 8, and a cooling zone 10 (first cooling zone 10A and second cooling zone 10B) in this order. The cooling zone 10 may be configured with only the first cooling zone 10A in accordance with the cooling amount and strip threading speed required according to the desired mechanical properties, or may be configured with two cooling zones including the first cooling zone 10A and the second cooling zone 10B as shown in FIG.

　冷却帯１０の鋼板搬送方向Ｘの下流には、急速冷却帯１５と、焼戻し帯１６と、がこの順で構成される焼鈍後熱処理設備１１が設置されている。製造される鋼板Ｓをめっき鋼板（合金化溶融亜鉛めっき鋼板）とする場合、焼鈍後熱処理設備１１は、鋼板めっき設備（合金化溶融亜鉛めっき設備）としてよく、鋼板搬送方向Ｘで、急速冷却帯１５の前に、めっき浸漬帯（溶融亜鉛めっき浸漬帯）１２と、めっき合金化帯１３と、を順に有していてもよい。焼鈍後熱処理設備１１は、鋼板めっき設備（合金化溶融亜鉛めっき設備）とする場合、本発明の鋼板製造設備１は、溶融亜鉛めっき鋼板製造設備または合金化溶融亜鉛めっき鋼板製造設備としてよい。
このとき、合金化反応の進行に必要な時間を確保する目的で、焼鈍後熱処理設備１１は、保熱帯１４を備えていてもよい。焼戻し帯１６は、加熱装置（焼戻し帯加熱装置）１７、保熱装置（焼戻し帯保熱装置）１８、冷却装置（焼戻し帯冷却装置）１９の順に構成されている。 Downstream of the cooling zone 10 in the steel sheet transport direction X, a post-annealing heat treatment facility 11 is installed, which is configured of a rapid cooling zone 15 and a tempering zone 16 in this order. When the steel sheet S to be manufactured is a plated steel sheet (galvannealed steel sheet), the post-annealing heat treatment facility 11 may be a steel sheet plating facility (galvannealed steel sheet), and may have a plating immersion zone (galvannealed steel sheet) 12 and a plating alloying zone 13 in this order before the rapid cooling zone 15 in the steel sheet transport direction X. When the post-annealing heat treatment facility 11 is a steel sheet plating facility (galvannealed steel sheet facility), the steel sheet manufacturing facility 1 of the present invention may be a galvannealed steel sheet manufacturing facility or a galvannealed steel sheet manufacturing facility.
In this case, in order to secure the time necessary for the alloying reaction to proceed, the post-annealing heat treatment equipment 11 may be provided with a holding zone 14. The tempering zone 16 is configured with a heating device (tempering zone heating device) 17, a heat retention device (tempering zone heat retention device) 18, and a cooling device (tempering zone cooling device) 19, in this order.

　本発明の鋼板製造設備１には、少なくとも均熱帯８と焼戻し帯１６に鋼板表面の温度を測定する温度測定装置２０が設置されており、鋼板の温度変化を監視できるようになっている。また、均熱帯８出側から焼戻し帯１６出側までのうちの少なくとも１箇所で、鋼板１のオーステナイト分率を測定する変態率測定装置２１を備えていてもよい。 The steel sheet manufacturing equipment 1 of the present invention is provided with temperature measuring devices 20 for measuring the temperature of the steel sheet surface at least in the soaking zone 8 and tempering zone 16, making it possible to monitor the temperature change of the steel sheet. In addition, at least one location between the exit side of the soaking zone 8 and the exit side of the tempering zone 16 may be provided with a transformation rate measuring device 21 for measuring the austenite fraction of the steel sheet 1.

　また、本発明の鋼板製造設備１は、管理装置３０を有していてよく、管理装置３０は、温度測定装置２０で測定した焼戻し帯１６での鋼板加熱温度に基づいて、鋼板Ｓの伸び値および穴広げ率を含む機械特性値を予測する機械特性予測部３１と、機械特性予測部３１で予測した機械特性値を鋼板Ｓの目標機械特性値（目標の伸び値、目標の穴広げ率等）に補正し、補正された機械特性値に基づいて熱処理条件を決定する熱処理条件演算部３２と、熱処理条件演算部３２で決定した熱処理条件に基づいて、連続焼鈍設備５を構成する各設備のうち、少なくとも均熱帯８での鋼板加熱温度を制御する熱処理条件制御部３３とを有する。
本発明の鋼板製造設備１は、機械特性予測部３１、熱処理条件演算部３２および熱処理条件制御部３３を有することで、得られる鋼板の機械特性の所望の機械特性からの変動を抑制することができる。
これらの装置の機能の詳細については、図２を参照しながら後述する。 Further, the steel sheet manufacturing equipment 1 of the present invention may have a management device 30, and the management device 30 has a mechanical property prediction unit 31 that predicts mechanical property values including an elongation value and a hole expansion ratio of the steel sheet S based on the steel sheet heating temperature in the tempering zone 16 measured by the temperature measurement device 20, a heat treatment condition calculation unit 32 that corrects the mechanical property values predicted by the mechanical property prediction unit 31 to target mechanical property values of the steel sheet S (target elongation value, target hole expansion ratio, etc.) and determines heat treatment conditions based on the corrected mechanical property values, and a heat treatment condition control unit 33 that controls the steel sheet heating temperature in at least the soaking zone 8 of each facility constituting the continuous annealing equipment 5 based on the heat treatment conditions determined by the heat treatment condition calculation unit 32.
The steel plate manufacturing equipment 1 of the present invention has a mechanical property prediction unit 31, a heat treatment condition calculation unit 32 and a heat treatment condition control unit 33, and is therefore capable of suppressing deviations in the mechanical properties of the obtained steel plate from the desired mechanical properties.
The functionality of these devices will be described in detail below with reference to FIG.

　＜各設備の詳細＞
　本発明の鋼板製造設備１が有する各設備の詳細について述べる。 <Details of each facility>
The individual pieces of equipment included in the steel sheet manufacturing facility 1 of the present invention will now be described in detail.

（１）予熱帯６
　常温～１００℃程度の温度でペイオフリール２から払い出された鋼板Ｓは、ルーパー４を通過し、予熱帯６に進入する。
　予熱帯６は、後述する加熱帯７、均熱帯８でのエネルギー効率向上のために用いられるが、鋼板製造設備１が予熱帯６を有していても、予熱帯６では加熱せずに、鋼板搬送方向Ｘに、次の加熱帯７から薄鋼板等の鋼板Ｓを加熱し始めてもよい。予熱帯６で鋼板Ｓを加熱する場合、薄鋼板等の鋼板Ｓは２００℃程度まで加熱される。予熱帯６の加熱方法は、次の加熱帯７で生じる高温の排気を利用する方式が考えられるが、目標の温度に到達すれば特に限定されない。 (1) Pre-tropical zone 6
The steel sheet S discharged from the pay-off reel 2 at a temperature between room temperature and about 100° C. passes through the looper 4 and enters the preheating zone 6.
The preheating zone 6 is used to improve energy efficiency in the heating zone 7 and soaking zone 8 described below, but even if the steel sheet manufacturing equipment 1 has the preheating zone 6, heating of the steel sheet S such as a thin steel sheet may be started in the steel sheet conveying direction X from the next heating zone 7 without heating in the preheating zone 6. When the steel sheet S is heated in the preheating zone 6, the steel sheet S such as a thin steel sheet is heated to about 200°C. A possible method for heating the preheating zone 6 is a method that utilizes high-temperature exhaust gas generated in the next heating zone 7, but is not particularly limited as long as the target temperature is reached.

（２）加熱帯７
　続いて、鋼板Ｓは加熱帯７に進入し、鋼板温度は均熱帯での保持時間を最大限確保するために焼鈍温度（均熱温度）と同程度の６００℃以上の加熱温度まで加熱される。また、この加熱温度は７００℃以下としてよい。加熱帯７では、加熱能力が高く炉の容積を小さくできることに加え、鋼板Ｓにめっきを施す場合には、後の工程でのめっき性確保のために鋼板表面の酸化還元反応を柔軟に制御可能であることから、直火加熱炉方式を採用することが好ましい。この方式により、短時間で目的の温度まで加熱することが可能となり、鋼板表面の状態の制御が容易となる。 (2) Heating Zone 7
Next, the steel sheet S enters the heating zone 7, where the steel sheet temperature is heated to a heating temperature of 600°C or more, which is approximately the same as the annealing temperature (soaking temperature), in order to maximize the holding time in the soaking zone. This heating temperature may be 700°C or less. In the heating zone 7, a direct-fire heating furnace method is preferably adopted because it has a high heating capacity and allows the volume of the furnace to be small, and when plating the steel sheet S, it is possible to flexibly control the oxidation-reduction reaction of the steel sheet surface to ensure plating properties in the subsequent process. This method makes it possible to heat the steel sheet to the desired temperature in a short time, making it easy to control the state of the steel sheet surface.

（３）均熱帯８
　続く均熱帯８では、加熱帯７で加熱された鋼板に対して、目標の焼鈍温度に向けての緩やかな加熱および焼鈍温度での保持を行う。
均熱帯８では、Ａ１変態点未満の温度まで加熱および保持を行う。これにより、α相の再結晶が進行し、圧延によって過度に微細化された結晶粒を適度に粗大化することができる。また、均熱帯８出側においてα相とγ相の相分率が調整可能になり、その後の冷却と組み合わせによって製品の機械特性を制御することができる。
さらに、未再結晶α相の残留を抑制するためには、上記温度域での滞在時間を２０秒以上確保することが好ましい。また、この温度域での滞在時間は６０秒以下とすることが好ましい。滞在時間の制御は加熱速度で行い、加熱帯７から焼鈍温度到達までの加熱速度は１０℃／ｓ以下とすることが好ましく、より好ましくは５℃／ｓ以下とする。
鋼板（薄鋼板）Ｓの均熱帯８での加熱方式としては、効率と加熱均一性の高さからガス燃焼による輻射加熱（ラジアントチューブ加熱）方式を採用することが好ましい。加えて、均熱帯出口付近で鋼板温度を安定化させるために、これらの加熱方式によって、均熱帯の炉温は目標焼鈍温度以上であることが好ましく、より好ましくは目標焼鈍温度＋５℃以上の範囲で制御する。また、均熱帯の炉温は目標焼鈍温度以上＋５０℃以下の範囲であることが好ましく、目標焼鈍温度以上＋２０℃以下の範囲であることがより好ましい。
均熱帯８は、図１に示すように上下に配置した搬送ロール間で鋼板Ｓを往復させることで炉内の滞在時間を確保してよい。また、炉自体の構造は入口から出口まで一体としてもよいが、再結晶域から焼鈍温度までの加熱を担う調整帯と焼鈍温度での保持を担う保持帯とで炉殻を分離してもよい。これにより、細かな温度制御が要求される保持帯の炉体積を小さくし制御性を向上させることもできる。 (3) Soaking Zone 8
In the subsequent soaking zone 8, the steel sheet heated in the heating zone 7 is gradually heated to the target annealing temperature and held at the annealing temperature.
In the soaking zone 8, the material is heated to a temperature below the A1 transformation point and held at that temperature. This promotes recrystallization of the α phase, and allows the crystal grains that have been excessively refined by rolling to be appropriately coarsened. In addition, the phase fractions of the α phase and the γ phase can be adjusted on the outlet side of the soaking zone 8, and the mechanical properties of the product can be controlled by subsequent cooling and combination.
Furthermore, in order to suppress the remaining of the unrecrystallized α phase, it is preferable to secure a residence time in the above temperature range of 20 seconds or more. Also, it is preferable that the residence time in this temperature range is 60 seconds or less. The residence time is controlled by the heating rate, and the heating rate from the heating zone 7 to the annealing temperature is preferably 10° C./s or less, more preferably 5° C./s or less.
As a heating method for the steel sheet (thin steel sheet) S in the soaking zone 8, it is preferable to adopt a radiant heating method (radiant tube heating) using gas combustion because of its high efficiency and heating uniformity. In addition, in order to stabilize the steel sheet temperature in the vicinity of the soaking zone outlet, the furnace temperature in the soaking zone is preferably controlled to be equal to or higher than the target annealing temperature, more preferably within a range of the target annealing temperature +5°C or more, by these heating methods. Moreover, the furnace temperature in the soaking zone is preferably in a range of the target annealing temperature or higher +50°C or lower, more preferably in a range of the target annealing temperature or higher +20°C or lower.
The soaking zone 8 may ensure the residence time in the furnace by reciprocating the steel sheet S between transport rolls arranged above and below as shown in Fig. 1. The structure of the furnace itself may be integrated from the inlet to the outlet, but the furnace shell may be separated into an adjustment zone for heating from the recrystallization region to the annealing temperature and a holding zone for maintaining the temperature at the annealing temperature. This can reduce the furnace volume of the holding zone, which requires fine temperature control, and improve controllability.

（４）冷却帯１０（第１冷却帯１０Ａ、第２冷却帯１０Ｂ）
　均熱帯８で目標焼鈍温度まで加熱された後、鋼板Ｓは冷却帯１０へと搬送され冷却が行われる。冷却速度不足による冷却中のフェライト変態を防止するという理由と、冷却速度過剰による冷却停止後の急激なベイナイト変態を防止するという理由から、冷却速度を設定することが好ましい。具体的には、冷却速度の範囲は、５℃／ｓ以上とすることが好ましい。また、冷却速度の範囲は、３０℃／ｓ以下とすることが好ましい。めっき工程よりも上流でマルテンサイト変態を生じさせず、一部のオーステナイト相をベイナイト相へと変態させるために、冷却停止温度はマルテンサイト変態開始温度以上５５０℃以下とすることが好ましく、４５０℃以上５５０℃以下の範囲に収めることがより好ましい。
また、ベイナイト変態を十分進行させるために、冷却停止温度到達後に１秒以上の保持時間で保持をすることが好ましく、２０秒以上の保持時間で保持をすることがより好ましい。また、この保持時間は１００秒以下とすることが好ましく、５０秒以下とすることがより好ましい。
冷却方式は、圧縮した気体噴流を衝突させるガスジェット冷却や、冷媒を内部に通したロールとの接触で冷却するロール冷却、水噴流による水冷や圧縮ガス微小水滴を混合したミスト冷却などが考えられるが、特に限定されない。後述の本実施例では、目標となる冷却速度を確保しつつ、沸騰による不安定な温度変化を起こさず、冷却停止温度を高精度に制御できるガスジェット冷却を採用した。
また、図１に示すように、冷却後にベイナイト変態をより進行させるために緩冷却または保熱を行う場合は、冷却帯１０は、第１冷却帯（急速冷却帯）１０Ａと第２冷却帯（緩冷却・保熱帯）１０Ｂの二つに分割してもよい。 (4) Cooling Zone 10 (First Cooling Zone 10A, Second Cooling Zone 10B)
After being heated to the target annealing temperature in the soaking zone 8, the steel sheet S is transported to the cooling zone 10 and cooled. It is preferable to set the cooling rate in order to prevent ferrite transformation during cooling due to insufficient cooling rate and to prevent rapid bainite transformation after cooling is stopped due to excessive cooling rate. Specifically, the cooling rate is preferably in the range of 5°C/s or more. Also, the cooling rate is preferably in the range of 30°C/s or less. In order to prevent martensite transformation from occurring upstream of the plating process and to transform a part of the austenite phase into the bainite phase, the cooling stop temperature is preferably in the range of the martensite transformation start temperature or more and 550°C or less, and more preferably in the range of 450°C or more and 550°C or less.
In order to allow the bainite transformation to proceed sufficiently, the holding time after reaching the cooling stop temperature is preferably 1 second or more, more preferably 20 seconds or more, and is preferably 100 seconds or less, more preferably 50 seconds or less.
The cooling method may be, but is not limited to, gas jet cooling, which causes a compressed gas jet to collide with the material, roll cooling, which causes cooling by contact with a roll through which a refrigerant passes, water cooling using a water jet, mist cooling, which mixes compressed gas with minute water droplets, etc. In the present embodiment described later, gas jet cooling was adopted, which can ensure a target cooling rate while preventing unstable temperature changes due to boiling and controlling the cooling stop temperature with high precision.
Furthermore, as shown in FIG. 1, when slow cooling or heat retention is performed after cooling in order to further advance the bainite transformation, the cooling zone 10 may be divided into two zones, a first cooling zone (rapid cooling zone) 10A and a second cooling zone (slow cooling/holding zone) 10B.

（５）めっき浸漬帯（溶融亜鉛めっき浸漬帯）１２、めっき合金化帯１３および保熱帯１４
　冷却帯１０で組織制御を行った後、鋼板Ｓは焼鈍後熱処理設備１１に搬送される。鋼板Ｓにめっき処理を施す場合には、焼鈍後熱処理設備１１は鋼板めっき設備としてよく、鋼板Ｓはこの鋼板めっき設備に搬送されて、めっき浸漬帯１２でめっき処理（例えば、亜鉛めっき処理）が行われる。
本発明では、めっきの方式としては、溶融した亜鉛を蓄えた亜鉛めっき浴へと鋼板を浸漬させる溶融亜鉛めっき法を採用してよい。なお、めっき浴通過後に亜鉛の付着量を制御するために、焼鈍後熱処理設備（鋼板めっき設備）１１は、余剰の溶融亜鉛を掻きとる装置を備えてもよい。
　めっき浸漬帯１２の工程の下流には、Ｚｎ－Ｆｅ合金化反応を進めるためのめっき合金化帯１３が備えられていてよい。このときの鋼板温度は４３０℃程度まで低下しているため、めっき合金化帯１３では合金化反応に必要な温度（５００℃程度）まで昇温される。めっき合金化帯１３での加熱方法は、燃焼排ガスによるガス加熱方式や誘導加熱、通電加熱方式などが考えられるが、特に限定されない。本発明では、めっき表面への影響が小さく、細かな出力制御が可能な誘導加熱方式を採用してよい。合金化反応の進行に必要な時間を確保する目的で、めっき合金化帯１３の下流側に保熱帯１４を設置してもよい。 (5) Galvanizing immersion zone (hot-dip galvanizing immersion zone) 12, galvanizing alloying zone 13, and retention zone 14
After the structure control is performed in the cooling zone 10, the steel sheet S is transported to a post-annealing heat treatment facility 11. When the steel sheet S is subjected to a plating treatment, the post-annealing heat treatment facility 11 may be a steel sheet plating facility, and the steel sheet S is transported to this steel sheet plating facility and subjected to a plating treatment (e.g., a zinc plating treatment) in a plating immersion zone 12.
In the present invention, the plating method may be a hot-dip galvanizing method in which the steel sheet is immersed in a galvanizing bath containing molten zinc. In order to control the amount of zinc deposited after passing through the plating bath, the post-annealing heat treatment equipment (steel sheet plating equipment) 11 may be equipped with a device for scraping off excess molten zinc.
A plating alloying zone 13 for promoting the Zn-Fe alloying reaction may be provided downstream of the plating immersion zone 12. Since the temperature of the steel sheet at this time is lowered to about 430°C, the temperature is raised to a temperature (about 500°C) required for the alloying reaction in the plating alloying zone 13. The heating method in the plating alloying zone 13 may be a gas heating method using combustion exhaust gas, induction heating, electric heating, or the like, but is not particularly limited. In the present invention, an induction heating method that has little effect on the plating surface and allows fine output control may be adopted. A holding zone 14 may be provided downstream of the plating alloying zone 13 in order to ensure the time required for the alloying reaction to proceed.

（６）急速冷却帯１５
　鋼板Ｓにめっき処理を施す場合（焼鈍後熱処理設備１１を鋼板めっき設備とする場合）、めっき合金化帯１３または保熱帯１４に続いて、めっき合金化反応が完了した後、未変態のオーステナイト相をマルテンサイト組織へと変態させるための急速冷却帯１５が設置されている。鋼板Ｓにめっき処理を施さない場合、急速冷却帯１５は、鋼板搬送方向Ｘに、冷却帯１０の下流に設置されてよい。
急速冷却帯１５での冷却方式としては、圧縮した気体噴流を衝突させるガスジェット冷却や、水噴流による水冷、圧縮ガス、微小水滴を混合したミスト冷却などが考えられるが、特に限定されない。本発明では、急速冷却を実現しつつ、冷却停止温度を高精度に制御するために、ミスト冷却とガスジェット冷却を組み合わせたものを使用してよい。鋼板Ｓにめっき処理を施す場合、めっき合金化帯１３または保熱帯１４を通過し、３５０～４５０℃程度となった鋼板Ｓを、急速冷却帯１５でマルテンサイト変態開始温度以下まで冷却する。過剰なベイナイト変態を防ぎつつ望んだ分率のマルテンサイト組織を得るため、このときの冷却速度は、５０℃／ｓ以上であることが好ましい。
一方、冷却速度の上限は特に設けないが、過度な急速冷却を行うと冷却時の熱変形により鋼板の平坦度が崩れる可能性があるため、冷却速度は１０００℃／ｓ以下とすることが好ましい。また、冷却停止温度は冷却後の自己焼き戻しを防ぐために２００℃以下とすることが好ましい。 (6) Rapid cooling zone 15
When the steel sheet S is subjected to a plating treatment (when the post-annealing heat treatment equipment 11 is used as a steel sheet plating equipment), a rapid cooling zone 15 is provided following the plating alloying zone 13 or the holding zone 14 in order to transform the untransformed austenite phase into a martensite structure after the plating alloying reaction is completed. When the steel sheet S is not subjected to a plating treatment, the rapid cooling zone 15 may be provided downstream of the cooling zone 10 in the steel sheet transport direction X.
The cooling method in the rapid cooling zone 15 may be gas jet cooling in which a compressed gas jet is collided, water cooling by a water jet, mist cooling in which compressed gas and minute water droplets are mixed, and the like, but is not particularly limited. In the present invention, a combination of mist cooling and gas jet cooling may be used in order to realize rapid cooling while controlling the cooling stop temperature with high precision. When plating is performed on the steel sheet S, the steel sheet S, which has passed through the plating alloying zone 13 or the holding zone 14 and reached a temperature of about 350 to 450°C, is cooled in the rapid cooling zone 15 to a martensitic transformation start temperature or lower. In order to obtain a martensite structure with a desired fraction while preventing excessive bainite transformation, the cooling rate at this time is preferably 50°C/s or higher.
On the other hand, although there is no particular upper limit to the cooling rate, the cooling rate is preferably 1000°C/s or less because excessively rapid cooling may cause the flatness of the steel sheet to be lost due to thermal deformation during cooling. Also, the cooling stop temperature is preferably 200°C or less to prevent self-tempering after cooling.

（７）焼戻し帯１６
　急速冷却帯１５でマルテンサイト組織を作りこんだ後、焼戻し帯１６にて焼戻しを行う。焼戻し帯１６は、入口から鋼板搬送方向Ｘに、加熱装置（焼戻し帯加熱装置）１７、保熱装置（焼戻し帯保熱装置）１８、冷却装置（焼戻し帯冷却装置）１９の順に構成されている。加熱装置１７での加熱温度はマルテンサイト組織を維持しつつ焼戻しによる靭性の向上の効果を得られるようにするという観点から設定してよい。具体的には、加熱装置１７での加熱温度は、２５０℃以上であることが好ましく、より好ましくは３００℃以上とする。また、加熱装置１７での加熱温度は、５００℃以下であることが好ましく、より好ましくは４００℃以下である。保熱装置１８では、加熱装置１７で加熱された鋼板の温度を保持し、保熱装置１８での保持時間は、焼戻しの効果を十分に得つつ、過剰なライン長の拡大を防ぐという観点から設定してよい。具体的には、保熱装置１８での保持時間は、２０秒以上とすることが好ましく、より好ましくは３０秒以上とする。また、保熱装置１８での保持時間は、１００秒以下とすることが好ましく、より好ましくは６０秒以下とする。
その後、冷却装置１９では、鋼板Ｓに対して常温まで冷却を行う。本構成により、適切な焼戻し処理を行うことができ、目標の機械特性が得られる。加熱装置１７での加熱は、ガスバーナ、通電加熱、誘導加熱などの方法から選択できるが、本発明では、制御性の観点から誘導加熱方式を採用してよい。保熱装置１８は、装置内の温度均一性の観点から電気ヒーターによるヒーター本体および炉壁からの輻射加熱方式を採用することが好ましいが、特に限定されない。定常状態では、炉温が目標焼戻し温度とほぼ同程度となるように制御を行ってよい。冷却装置１９は、冷却効率の観点からミスト冷却方式とし、冷却と同時に表面に付着した水分を除去するためにガスジェット装置も設置することが好ましいが、目標冷却速度に調整できれば特に限定されない。 (7) Tempering zone 16
After the martensite structure is created in the rapid cooling zone 15, tempering is performed in the tempering zone 16. The tempering zone 16 is configured in the following order from the entrance in the steel sheet conveying direction X: a heating device (tempering zone heating device) 17, a heat retention device (tempering zone heat retention device) 18, and a cooling device (tempering zone cooling device) 19. The heating temperature in the heating device 17 may be set from the viewpoint of obtaining the effect of improving toughness by tempering while maintaining the martensite structure. Specifically, the heating temperature in the heating device 17 is preferably 250°C or higher, more preferably 300°C or higher. In addition, the heating temperature in the heating device 17 is preferably 500°C or lower, more preferably 400°C or lower. In the heat retention device 18, the temperature of the steel sheet heated in the heating device 17 is maintained, and the retention time in the heat retention device 18 may be set from the viewpoint of preventing excessive expansion of the line length while obtaining a sufficient effect of tempering. Specifically, the retention time in the heat retaining device 18 is preferably 20 seconds or more, more preferably 30 seconds or more, and is preferably 100 seconds or less, more preferably 60 seconds or less.
Thereafter, the cooling device 19 cools the steel sheet S to room temperature. With this configuration, an appropriate tempering process can be performed, and the target mechanical properties can be obtained. The heating device 17 can be selected from methods such as gas burners, electrical heating, and induction heating, but in the present invention, an induction heating method may be adopted from the viewpoint of controllability. The heat retention device 18 is preferably a radiant heating method from the heater body and furnace wall using an electric heater from the viewpoint of temperature uniformity within the device, but is not particularly limited. In a steady state, the furnace temperature may be controlled to be approximately the same as the target tempering temperature. The cooling device 19 is preferably a mist cooling method from the viewpoint of cooling efficiency, and a gas jet device is also preferably installed to remove moisture attached to the surface at the same time as cooling, but is not particularly limited as long as it can be adjusted to the target cooling rate.

（８）温度測定装置２０
　上述の各帯のうち、少なくとも均熱帯８と焼戻し帯１６には、鋼板の表面温度を測定する温度測定装置（温度計）２０が設置されている。これらの温度測定装置２０によって、熱処理中の鋼板Ｓの温度履歴を知ることが可能になる。均熱帯８のように設備長が長い設備に設ける場合は、途中の温度履歴を確認するために帯内にも温度計を設置してもよい。
上記温度計の各帯内における設置位置は、具体的には、例えば、均熱帯８においては、均熱帯入口（＝加熱帯出口）、均熱帯途中、均熱帯出口が挙げられる。また、上記温度計の各帯内における設置位置は、焼戻し帯１６においては、焼戻し帯入口、焼戻し帯中間、焼戻し帯出口が挙げられる。
温度測定装置２０による温度測定の方式は特に限定されないが、鋼板が発する赤外線を感知して温度を測定する放射温度計とすることが好ましい。放射温度計は、周囲の炉体が発する赤外線の反射光の影響を受けるため、放射温度計に備えられる測定部から検出部までの間に覆いを設けてもよい。また、放射温度計は、鋼板表面の放射率の影響も受けるため、温度測定方法としては、炉内搬送ロールと鋼板Ｓの間のくさび状の空間を利用した多重反射式の測定方法を採用してもよい。 (8) Temperature measuring device 20
Of the above-mentioned zones, at least the soaking zone 8 and the tempering zone 16 are provided with temperature measuring devices (thermometers) 20 for measuring the surface temperature of the steel sheet. These temperature measuring devices 20 make it possible to know the temperature history of the steel sheet S during the heat treatment. When a thermometer is provided in a facility with a long equipment length, such as the soaking zone 8, a thermometer may also be provided in the zone to check the temperature history during the treatment.
Specific examples of the installation position of the thermometer within each zone include the entrance of the soaking zone (=exit of the heating zone), midway through the soaking zone, and the exit of the soaking zone in the soaking zone 8. Furthermore, examples of the installation position of the thermometer within each zone include the entrance, middle, and exit of the tempering zone in the tempering zone 16.
The method of temperature measurement by the temperature measuring device 20 is not particularly limited, but it is preferable to use a radiation thermometer that senses infrared rays emitted by the steel sheet to measure the temperature. Since the radiation thermometer is affected by the reflected light of infrared rays emitted by the surrounding furnace body, a cover may be provided between the measurement unit and the detection unit of the radiation thermometer. In addition, since the radiation thermometer is also affected by the emissivity of the steel sheet surface, a multiple reflection type measurement method that utilizes a wedge-shaped space between the in-furnace transport roll and the steel sheet S may be used as the temperature measurement method.

（９）変態率測定装置２１
　均熱帯８出側から焼戻し帯１６出側までにおいて、鋼板Ｓのオーステナイト分率を測定する変態率測定装置２１が１箇所以上備え付けられていることが好ましい。
これは、測定したオーステナイト分率に基づいて、鋼板Ｓの機械特性値（例えば、伸び値、穴広げ率）を予測することによって、焼戻し帯１６での鋼板加熱温度のみから鋼板Ｓの伸び値や穴広げ率等の機械特性値を予測するよりも、鋼板Ｓの機械特性値の予測精度が向上するためである。この変態率測定装置２１によって、目標焼鈍温度到達後の鋼板のα相およびγ相の分率（変態率）の情報を取得できる。
この変態率測定装置２１は、測定したオーステナイト分率に基づき、連続焼鈍設備５の操業条件を調整する目的で設けられ、所望の機械特性を安定して得ることを可能とする。
変態率の測定方式は特に限定されないが、変態率測定装置２１は、磁気検出器、すなわち鋼板Ｓ（鋼帯）の磁気変態率を測定する装置としてよく、磁場を発生する駆動コイルと、鋼板Ｓを通過した磁場を測定する検出コイルとから構成される磁気変態率測定装置として、オーステナイト分率を測定することができる。
他の手法としては、例えば、Ｘ線回折法を応用した方式を採用してもよい。このＸ線回折法を応用した方式では、γ相とα相は結晶構造の差異により、鋼板にＸ線を照射すると各々固有の角度で回折ピークを生じるため、この回折ピーク強度によりオーステナイト分率を定量化することができる。 (9) Transformation rate measuring device 21
It is preferable that one or more transformation rate measuring devices 21 for measuring the austenite fraction of the steel sheet S are provided from the exit side of the soaking zone 8 to the exit side of the tempering zone 16 .
This is because predicting the mechanical property values (e.g., elongation value, hole expansion ratio) of the steel sheet S based on the measured austenite fraction improves the prediction accuracy of the mechanical property values of the steel sheet S, compared to predicting the mechanical property values such as the elongation value and hole expansion ratio of the steel sheet S only from the steel sheet heating temperature in the tempering zone 16. This transformation ratio measuring device 21 makes it possible to obtain information on the fractions (transformation ratios) of the α phase and the γ phase of the steel sheet after the target annealing temperature is reached.
This transformation rate measuring device 21 is provided for the purpose of adjusting the operating conditions of the continuous annealing equipment 5 based on the measured austenite fraction, and makes it possible to stably obtain desired mechanical properties.
Although the method for measuring the transformation rate is not particularly limited, the transformation rate measuring device 21 may be a magnetic detector, i.e., a device for measuring the magnetic transformation rate of the steel sheet S (steel strip), and can measure the austenite fraction as a magnetic transformation rate measuring device composed of a driving coil that generates a magnetic field and a detection coil that measures the magnetic field that has passed through the steel sheet S.
As another method, for example, a method applying an X-ray diffraction method may be adopted. In this method applying an X-ray diffraction method, the γ phase and the α phase each produce a diffraction peak at a unique angle when an X-ray is irradiated onto a steel sheet due to the difference in crystal structure between the phases, and the austenite fraction can be quantified based on the intensity of this diffraction peak.

　（機械特性値（伸び値、穴広げ率））
　本発明の鋼板Ｓの機械特性値として、伸び値は、例えば、ＪＩＳ　Ｚ２２４１（２０１１）の試験方法に基づいて決定する。
伸び値を測定するためのサンプルは、本発明における焼戻し帯冷却装置１９による処理後、且つコイラー巻取り直前にシャーカットされた鋼板から採取することが好ましい。また、１コイルにつき、サンプルは操業中コイルの先端および尾端から採取される。
本発明の鋼板Ｓの機械特性値として、穴広げ率は、例えば、ＪＩＳ　Ｚ２２５６（２０１０）の試験方法に基づいて決定する。
　穴広げ率を測定するためのサンプルは、コイラー巻取り直前にシャーカットされた鋼板から採取することが好ましい。また、１コイルにつき、サンプルは操業中コイルの先端および尾端から採取される。 (Mechanical property values (elongation value, hole expansion ratio))
As a mechanical property value of the steel sheet S of the present invention, the elongation value is determined, for example, based on the test method of JIS Z2241 (2011).
The samples for measuring the elongation value are preferably taken from the steel sheet shear-cut after the treatment by the tempering zone cooling device 19 in the present invention and immediately before winding by the coiler. For each coil, samples are taken from the head and tail ends of the coil during operation.
As a mechanical property value of the steel sheet S of the present invention, the hole expansion ratio is determined, for example, based on the test method of JIS Z2256 (2010).
The samples for measuring the hole expansion ratio are preferably taken from the shear-cut steel sheet immediately before winding on the coiler. For each coil, samples are taken from the head and tail ends of the coil during operation.

　＜制御方法＞
　図２は、本発明における鋼板製造設備の制御方法を説明するためのフロー図である。
　管理装置３０が有する機械特性予測部３１、熱処理条件演算部３２、熱処理条件制御部３３の構成とこれらが行う処理について、図２のフローチャートを参照しながら説明する。 <Control method>
FIG. 2 is a flow chart for explaining a method for controlling a steel sheet manufacturing facility according to the present invention.
The configurations of the mechanical property prediction unit 31, the heat treatment condition calculation unit 32, and the heat treatment condition control unit 33 of the management device 30 and the processes performed by these units will be described with reference to the flowchart of FIG.

（１）機械特性予測部３１、機械特性予測ステップ
　鋼板製造設備１において、新規鋼板Ｓを製造し（ステップＳ１）、鋼板Ｓ（コイル）のつなぎ目部分において、すなわち、先行材と後行材との接続位置で、製造条件の変更が必要となるコイルであるか否かを判定する（ステップＳ２）。製造条件の変更が必要ない場合、製造条件は変更せずに、鋼板製造設備１は、鋼板Ｓの製造を続ける。このステップＳ２における判定は、鋼板製造設備１の管理装置３０内の制御部（図示せず）が行ってもよいし、鋼板製造設備１が有するその他の制御部（図示せず）が行ってもよい。
　例えば、先行材と後行材とで、板厚、鋼成分組成、目標機械特性が異なる場合、管理装置３０は製造条件の変更を必要と判定する。
　製造条件の変更が必要である場合は、機械特性予測ステップＳ３において、機械特性予測部３１が、焼戻し帯（再加熱帯）１６での操業条件（鋼板加熱温度）に基づいて、鋼板Ｓ（後行材）の機械特性値を予測する。機械特性値としては、伸び値と穴広げ率とが挙げられる。
　機械特性予測部３１に入力する操業条件としては、その他に、均熱帯８より下流側の設備での操業条件が挙げられ、この操業条件において後行材が焼戻し帯（再加熱帯）１６までの工程を完了した際の機械特性を予測する。このとき、変態率測定装置２１で測定したオーステナイト分率結果をさらに操業条件に加え、このオーステナイト分率と操業条件とに基づいて、機械特性値の予測を実施することで、機械特性値の予測精度が向上する。温度測定だけでは組織を間接的に予測するということになるため、さらに直接オーステナイト分率を測定することで、熱処理工程を経た後の機械特性の予測精度が向上する。
　機械特性予測部３１が行う機械特性の予測方法としては、伸び値、穴広げ率に関しては、例えば、熱処理の実験の結果を元に回帰分析を行って算出した実験式や、操業条件と材質測定結果を基にしたデータサイエンスによる方式によって構築された伸び値予測データベース等を用いる方法が考えられるが、特に限定されない。
本発明では新規品種への予測精度を向上させるという観点から、各鋼板の熱処理の実験結果を基にした回帰分析の方法を用いることができる。この手順としては実機を模擬した熱処理をオフラインや実験にて行い、その際に、伸び値であれば、ＪＩＳ　Ｚ２２４１（２０１１）の試験方法の結果に基づいて回帰分析を行い、穴広げ率であれば、ＪＩＳＺ２２５６（２０１０）の試験方法の結果に基づいて回帰分析を行って、伸び値、穴広げ率を予測する。
　機械特性予測部３１は、上記の伸び値予測データベースを有する記憶部３４にデータを記録したり、該データに基づいて鋼板Ｓの伸び値等を予測したりすることができる。 (1) Mechanical property prediction unit 31, mechanical property prediction step In the steel sheet manufacturing equipment 1, a new steel sheet S is manufactured (step S1), and it is determined whether or not the coil requires a change in manufacturing conditions at the joint portion of the steel sheet S (coil), i.e., at the connection position between the preceding material and the succeeding material (step S2). If a change in manufacturing conditions is not required, the steel sheet manufacturing equipment 1 continues manufacturing the steel sheet S without changing the manufacturing conditions. This determination in step S2 may be made by a control unit (not shown) in the management device 30 of the steel sheet manufacturing equipment 1, or may be made by another control unit (not shown) of the steel sheet manufacturing equipment 1.
For example, if the plate thickness, steel composition, and target mechanical properties differ between the preceding and succeeding materials, the management device 30 determines that the manufacturing conditions need to be changed.
When the manufacturing conditions need to be changed, in a mechanical property prediction step S3, the mechanical property prediction unit 31 predicts the mechanical property values of the steel sheet S (successor material) based on the operating conditions (steel sheet heating temperature) in the tempering zone (reheating zone) 16. Examples of the mechanical property values include elongation value and hole expansion ratio.
Other operational conditions input to the mechanical property prediction unit 31 include the operational conditions of the equipment downstream of the soaking zone 8, and the mechanical properties are predicted when the subsequent material has completed the process up to the tempering zone (reheating zone) 16 under these operational conditions. At this time, the austenite fraction result measured by the transformation rate measurement device 21 is further added to the operational conditions, and the mechanical property values are predicted based on this austenite fraction and the operational conditions, thereby improving the prediction accuracy of the mechanical property values. Since temperature measurement alone results in indirect prediction of the structure, by further directly measuring the austenite fraction, the prediction accuracy of the mechanical properties after the heat treatment process is improved.
As for the method of predicting mechanical properties performed by the mechanical property prediction unit 31, with regard to elongation value and hole expansion ratio, for example, a method using an empirical formula calculated by performing regression analysis based on the results of heat treatment experiments, or an elongation value prediction database constructed using a data science method based on operating conditions and material measurement results, etc., can be considered, but is not particularly limited.
In the present invention, from the viewpoint of improving prediction accuracy for new product types, a regression analysis method based on the experimental results of heat treatment of each steel sheet can be used. In this procedure, heat treatment simulating an actual machine is performed offline or experimentally, and in this case, regression analysis is performed based on the results of the test method of JIS Z2241 (2011) for elongation value, and regression analysis is performed based on the results of the test method of JIS Z2256 (2010) for hole expansion ratio to predict elongation value and hole expansion ratio.
The mechanical property prediction unit 31 can record data in a memory unit 34 having the above-mentioned elongation value prediction database, and can predict the elongation value, etc. of the steel sheet S based on the data.

（２）熱処理条件演算部３２、熱処理条件演算ステップ
　熱処理条件演算ステップＳ４では、機械特性予測ステップＳ３において機械特性予測部３１が予測した鋼板Ｓ（後行材）の機械特性値を、目標機械特性値に補正し、補正された機械特性値に基づいて連続焼鈍設備５での熱処理条件を演算する。
ここでいう補正とは、熱処理条件を演算するための機械特性値を、予測された機械特性値から予め設定された目標機械特性値に変更することを指す。
このとき、熱処理条件演算部３２は、均熱帯８での鋼板加熱条件の変更のみで目標機械特性値に補正可能と判断した場合（ステップＳ５）、均熱帯８での鋼板加熱温度の条件を演算し、決定する（ステップＳ６ａ）。
一方、均熱帯８での鋼板加熱温度の変更のみでは、目標機械特性値に補正することはできないと判断した場合（ステップＳ５）、熱処理条件演算装置３２は、均熱帯８の加熱温度の他に、さらに冷却帯１０での鋼板冷却条件を演算する（ステップＳ６ｂ）。
熱処理条件（均熱帯８での鋼板加熱温度、冷却帯１０での鋼板冷却条件）の決定方法としては、例えば、実験の結果を元に回帰分析を行って算出した実験式や、操業条件と材質測定結果を基にしたデータサイエンスによる方式によって構築された熱処理条件データベースを用いる方法が考えられるが特に限定されない。本発明では、新規品種への予測精度の観点から、各鋼板の熱処理の実験結果を基にした回帰分析の方法を用いることができる。この手順としては実機を模擬した熱処理をオフラインや実験にて行い、その結果に基づいて回帰分析を行って伸び値、穴広げ率等を予測することができる。
　冷却帯１０の鋼板冷却条件としては、特に限定されないが、例えば、冷却帯１０での冷却停止温度、冷却速度が挙げられる。これらの冷却停止温度や冷却速度は、冷却帯１０内に設置された温度計にて測定することにより得ることができる。
　熱処理条件演算部３２は、上記の熱処理条件データベースを有する記憶部３４にデータを記録したり、該データに基づいて鋼板Ｓの熱処理条件の演算および決定を行ったりすることができる。 (2) Heat treatment condition calculation unit 32, heat treatment condition calculation step In the heat treatment condition calculation step S4, the mechanical property values of the steel sheet S (successor material) predicted by the mechanical property prediction unit 31 in the mechanical property prediction step S3 are corrected to target mechanical property values, and the heat treatment conditions in the continuous annealing equipment 5 are calculated based on the corrected mechanical property values.
The term "correction" used here refers to changing the mechanical characteristic values for calculating the heat treatment conditions from predicted mechanical characteristic values to preset target mechanical characteristic values.
At this time, if the heat treatment condition calculation unit 32 determines that the target mechanical characteristic values can be corrected by simply changing the steel sheet heating conditions in the soaking zone 8 (step S5), it calculates and determines the conditions of the steel sheet heating temperature in the soaking zone 8 (step S6a).
On the other hand, when it is determined that the target mechanical characteristic value cannot be corrected by only changing the steel sheet heating temperature in the soaking zone 8 (step S5), the heat treatment condition computing device 32 computes the steel sheet cooling conditions in the cooling zone 10 in addition to the heating temperature in the soaking zone 8 (step S6b).
As a method for determining the heat treatment conditions (the steel sheet heating temperature in the soaking zone 8, the steel sheet cooling conditions in the cooling zone 10), for example, an empirical formula calculated by performing regression analysis based on the results of an experiment, or a method using a heat treatment condition database constructed by a data science method based on the operating conditions and the material measurement results can be considered, but is not particularly limited. In the present invention, from the viewpoint of prediction accuracy for new varieties, a regression analysis method based on the experimental results of the heat treatment of each steel sheet can be used. In this procedure, a heat treatment simulating an actual machine is performed offline or in an experiment, and a regression analysis is performed based on the results to predict the elongation value, hole expansion ratio, etc.
The cooling conditions of the steel sheet in the cooling zone 10 are not particularly limited, but include, for example, a cooling stop temperature and a cooling rate in the cooling zone 10. The cooling stop temperature and the cooling rate can be obtained by measuring with a thermometer installed in the cooling zone 10.
The heat treatment condition calculation unit 32 can record data in the memory unit 34 having the above-mentioned heat treatment condition database, and can calculate and determine the heat treatment conditions for the steel sheet S based on the data.

（３）熱処理条件制御部３３、熱処理条件制御ステップ
　熱処理条件制御ステップＳ７では、熱処理条件制御部３３が、熱処理条件演算部３２で決定した熱処理条件に基づいて、均熱帯８での鋼板加熱温度、あるいはさらに冷却帯１０での鋼板冷却条件を制御する。
　上記熱処理条件に基づいて、均熱帯９での鋼板加熱温度のみならず、さらに冷却帯１０での鋼板冷却条件を制御することで、鋼板Ｓ（後行帯）の機械特性（伸び値、穴広げ率）はより精度よく制御することができる。 (3) Heat Treatment Condition Control Unit 33, Heat Treatment Condition Control Step In the heat treatment condition control step S7, the heat treatment condition control unit 33 controls the steel sheet heating temperature in the soaking zone 8, or further the steel sheet cooling conditions in the cooling zone 10, based on the heat treatment conditions determined by the heat treatment condition calculation unit 32.
By controlling not only the steel sheet heating temperature in the soaking zone 9 but also the steel sheet cooling conditions in the cooling zone 10 based on the above heat treatment conditions, the mechanical properties (elongation value, hole expansion ratio) of the steel sheet S (trailing zone) can be controlled with greater precision.

（４）定常状態への移行
　管理装置３０は、焼戻し帯（再加熱帯）１６で測定された鋼板加熱温度に基づいて決定した熱処理条件が、後行材の目標熱処理条件を満たしているか否かを判定する（ステップＳ８）。後行材の目標熱処理条件を満たしていると判定した場合、管理装置３０は、前述した機械特性予測ステップＳ３、熱処理条件演算ステッＳ４、熱処理条件制御ステップＳ７での制御を停止し、後行材について、上記の目標熱処理条件以外の熱処理条件（定常熱処理条件）の調整（定常状態への移行）を行う。ここでいう、定常状態は、目標熱処理条件を含め、熱処理条件が所望の条件に到達している状態のことを指す。これにより、本発明における鋼板製造設備の制御の処理は終了する。一方、後行材の目標熱処理条件を満たしていないと判定した場合、再度機械特性予測が行われる（ステップＳ３）。 (4) Transition to a steady state The management device 30 judges whether the heat treatment conditions determined based on the steel sheet heating temperature measured in the tempering zone (reheat zone) 16 satisfy the target heat treatment conditions of the following material (step S8). If it is judged that the target heat treatment conditions of the following material are satisfied, the management device 30 stops the control in the above-mentioned mechanical property prediction step S3, heat treatment condition calculation step S4, and heat treatment condition control step S7, and adjusts the heat treatment conditions (steady heat treatment conditions) other than the above target heat treatment conditions for the following material (transition to a steady state). The steady state here refers to a state in which the heat treatment conditions, including the target heat treatment conditions, have reached the desired conditions. This ends the process of controlling the steel sheet manufacturing equipment in the present invention. On the other hand, if it is judged that the target heat treatment conditions of the following material are not satisfied, mechanical property prediction is performed again (step S3).

　図２を参照しながら説明した制御を行うことで、例えば、制御遅れが生じ、後行材の目標となる焼戻し条件に対して、焼戻し帯１６での操業条件が異なり、所望の機械特性値が得られなくなることが懸念される場合でも、鋼板加熱温度の情報を機械特性予測部３１に入力し、目標機械特性値に補正するために必要な連続焼鈍設備５での熱処理条件を熱処理条件演算部３２で演算し、熱処理条件制御部３３により均熱帯８および／または冷却帯１０の熱処理条件を制御することで焼戻し帯１６での制御遅れを打ち消すことができる。
このようにして、得られる鋼板について、機械特性の所望の機械特性からの変動を小さくすることができ、従来の鋼板製造設備と比べ、目標の機械特性を長手方向にわたって安定的に得ることが可能になる。 By performing the control described with reference to FIG. 2 , even if there is a concern that a control delay will occur and the operating conditions in the tempering zone 16 will differ from the target tempering conditions for the subsequent material, making it possible to obtain the desired mechanical property values, information on the steel sheet heating temperature can be input to the mechanical property prediction unit 31, the heat treatment conditions in the continuous annealing equipment 5 required for correcting the values to the target mechanical property values can be calculated by the heat treatment condition calculation unit 32, and the heat treatment conditions in the soaking zone 8 and/or cooling zone 10 can be controlled by the heat treatment condition control unit 33, thereby canceling out the control delay in the tempering zone 16.
In this way, the deviation of the mechanical properties of the resulting steel plate from the desired mechanical properties can be reduced, and the target mechanical properties can be stably obtained in the longitudinal direction compared to conventional steel plate manufacturing equipment.

　上述した本発明の実施形態に係る鋼板製造設備を用いて、薄鋼板（コイル、鋼帯）を製造した。製品の機械特性のばらつきと歩留まりを調べるために強度レベルが７８０ＭＰａ級、９８０ＭＰａ級、１１８０ＭＰａ級である３種類の製品を続けて製造した。各強度別に５本ずつ続けて通板し、３種類計１５本を１セットとして１０セット分、合計１５０本を各例で製造した。板厚は１．０～２．０ｍｍの範囲で、セット内ではほぼ一定の板厚となるように製造順を決定し、徐々に板厚が変化するセットを繋げて製造した。
また、同一セット内に含まれる同一強度の製品は、連続鋳造機において全て異なるロットで鋳造されたスラブを素材として製造した。より具体的には、製造管理範囲内ではあるが各スラブの化学成分はばらついており変態挙動も均一にはなっていない。 Thin steel sheets (coils, steel strips) were manufactured using the steel sheet manufacturing equipment according to the embodiment of the present invention described above. In order to investigate the variation in mechanical properties and yield of the products, three types of products with strength levels of 780 MPa, 980 MPa, and 1180 MPa were manufactured in succession. Five pieces of each strength were passed through in succession, and 10 sets of 15 pieces of the three types were manufactured in one set, for a total of 150 pieces in each example. The plate thickness was in the range of 1.0 to 2.0 mm, and the manufacturing order was determined so that the plate thickness was approximately constant within the set, and the sets in which the plate thickness gradually changed were connected to manufacture.
In addition, products with the same strength included in the same set were all manufactured using slabs cast in different lots in a continuous casting machine. More specifically, although within the manufacturing control range, the chemical compositions of each slab vary and the transformation behavior is not uniform.

　各々のスラブは常法で熱間圧延、酸洗、必要に応じ焼鈍、冷間圧延を施した後、従来の焼鈍設備または本発明の焼鈍設備を用いて熱処理し、その後冷却、めっき等の後処理を実施した。最終製品のコイル先端から１０ｍ位置で採取されたサンプルの測定結果を代表値として同一強度の製品同士の特性ばらつきを調べた。また、異なる強度の製品同士の接続位置では、接続位置から前後１００ｍの範囲で１０ｍおきに分析用のサンプルを採取し、機械特性が出荷基準を満たさない領域を調べ、元のコイル長に対する出荷可能な長さの割合を接続部の歩留まりとして算出した。接続部の歩留まりは９０％以上を合格とした。
なお、引張り試験片はＪＩＳ５号とし、引張り試験はＪＩＳ　Ｚ２２４１（２０１１）に従って行った。７８０ＭＰａ、９８０ＭＰａ、１１８０ＭＰａ級の各強度において、必要な強度範囲はそれぞれ７８０ＭＰａ以上、９８０ＭＰａ以上、１１８０ＭＰａ以上、延性は１７％以上、１５％以上、１２％以上である。
また、穴広げ試験は、ＪＩＳ　Ｚ２２５６（２０１０）に従って行った。必要な穴広げ率は、７８０ＭＰａ級、９８０ＭＰａ級、１１８０ＭＰａ級の各強度において、６５％以上、５０％以上、４０％以上である。 Each slab was hot-rolled, pickled, annealed and cold-rolled as required, and then heat-treated using a conventional annealing facility or the annealing facility of the present invention, followed by cooling, plating and other post-treatments. The measurement results of samples taken 10 m from the coil tip of the final product were used as representative values to examine the characteristic variation between products of the same strength. In addition, at the connection points between products of different strength, samples for analysis were taken every 10 m within a range of 100 m before and after the connection point, and the area where the mechanical properties did not meet the shipping standard was examined, and the ratio of the shippable length to the original coil length was calculated as the yield of the connection. A connection yield of 90% or more was considered to be acceptable.
The tensile test specimen was JIS No. 5, and the tensile test was performed in accordance with JIS Z2241 (2011). For the strengths of 780 MPa, 980 MPa, and 1180 MPa, the required strength ranges are 780 MPa or more, 980 MPa or more, and 1180 MPa or more, respectively, and the ductility is 17% or more, 15% or more, and 12% or more.
The hole expansion test was performed in accordance with JIS Z2256 (2010). The required hole expansion ratios are 65% or more, 50% or more, and 40% or more for the strengths of 780 MPa class, 980 MPa class, and 1180 MPa class, respectively.

　焼鈍炉の操業条件は、鋼板温度が各製品の規定範囲に収まるように制御した。ライン速度は６０～１２０ｍｐｍの範囲で製造し、板厚による鋼板温度の変化を制御した。加熱帯（直火加熱）出口の鋼板温度は６００～７００℃の範囲に収め、焼鈍温度は７５０～８７０℃の範囲とした。均熱帯の炉温は出口の鋼板温度が目標値となるよう制御した。その後、冷却や溶融亜鉛めっき、合金化処理等を経て最終製品から材料試験片を複数採取し機械特性のばらつきを調査した。 The operating conditions of the annealing furnace were controlled so that the steel plate temperature was within the specified range for each product. The line speed was in the range of 60 to 120 mpm, and the change in steel plate temperature due to plate thickness was controlled. The steel plate temperature at the exit of the heating zone (direct flame heating) was kept in the range of 600 to 700°C, and the annealing temperature was in the range of 750 to 870°C. The furnace temperature in the soaking zone was controlled so that the steel plate temperature at the exit was the target value. After cooling, hot-dip galvanizing, alloying treatment, etc., multiple material test pieces were taken from the final product to investigate the variation in mechanical properties.

　表１に各製造条件による製造結果を示す。 Table 1 shows the production results under each production condition.

Figure JPOXMLDOC01-appb-T000001
 
Figure JPOXMLDOC01-appb-T000001
  

　比較例１は、引用文献１に記載の予熱帯、加熱帯、均熱帯、冷却帯、めっき帯、めっき合金化帯、最終冷却帯から構成される従来のＣＧＬを用いて、上記の素材から製品を製造した例である。
　比較例２は、比較例１に対してめっき合金化帯の後に焼戻し帯を設けた例である。
　比較例３は、比較例２の焼鈍炉出側（冷却帯の後）に、誘導加熱装置を設けた例である。
　これらの比較例では、焼戻し帯（再加熱帯）を用いた場合でも、焼戻し帯での鋼板加熱温度に基づく連続焼鈍設備の制御は「未実施」とした。 Comparative Example 1 is an example in which a product was manufactured from the above-mentioned material by using a conventional CGL described in Cited Document 1, which is composed of a preheating zone, a heating zone, a soaking zone, a cooling zone, a plating zone, a plating alloying zone, and a final cooling zone.
Comparative Example 2 is an example in which a tempering zone was provided after the plating alloying zone in comparison with Comparative Example 1.
Comparative Example 3 is an example in which an induction heating device is provided on the exit side of the annealing furnace of Comparative Example 2 (after the cooling zone).
In these comparative examples, even when a tempering zone (reheating zone) was used, control of the continuous annealing equipment based on the steel sheet heating temperature in the tempering zone was "not performed."

　表１に示すように、比較例１では、同一強度の製品内でのＴＳは大きくばらつき、グレード毎の下限値を下回るものも存在した。また、焼戻し帯における焼戻しを実施していないため、延性の合格基準を満たすものを製造することができず、接続部での歩留まりを算出できなかった。表１では、歩留まりは「－」と示す。 As shown in Table 1, in Comparative Example 1, TS varied widely within products of the same strength, with some falling below the lower limit for each grade. In addition, because tempering was not performed in the tempering zone, it was not possible to manufacture products that met the ductility acceptance criteria, and it was not possible to calculate the yield at the joint. In Table 1, the yield is indicated as "-".

　比較例２では、焼戻し帯における焼戻しを行うことで、比較例１より延性が向上し、合格基準内の製品を製造することが可能になったが、焼鈍炉での加熱温度や焼戻し帯の制御遅れが生じることで、鋼板温度の制御が目標から外れる部分が多かった。さらにコイル内でも機械特性のばらつきは大きく、また、接続部では材試基準を満たさない領域が広く発生しており、接続部での歩留まりは低位となっていた。 In Comparative Example 2, tempering in the tempering zone improved ductility compared to Comparative Example 1, making it possible to manufacture products that met the pass criteria; however, delays in controlling the heating temperature in the annealing furnace and the tempering zone meant that the steel sheet temperature control was off target in many areas. Furthermore, there was a large variation in mechanical properties even within the coil, and there were large areas in the joints that did not meet the material testing criteria, resulting in low yields at the joints.

　比較例３では、誘導加熱装置によって焼鈍温度の制御範囲が広がり、ＴＳ外れは発生しなかった。しかしながら、焼戻し帯での鋼板加熱温度に基づく連続焼鈍設備の制御を行わなかったため、延性のばらつきは大きく、合格基準を満たさないものが発生した。また、接続部での歩留まりも十分に改善しなかった。 In Comparative Example 3, the induction heating device expanded the control range of the annealing temperature, and no TS deviations occurred. However, because the continuous annealing equipment was not controlled based on the steel plate heating temperature in the tempering zone, there was a large variation in ductility, and some products did not meet the acceptance criteria. In addition, the yield at the joints was not sufficiently improved.

　これらの比較例に対し、実施例１は、本発明における鋼板製造設備の制御方法を用いて、上記の素材から製品を製造した結果である。
　実施例３は、実施例１の誘導加熱装置下流に変態率測定装置を設置した例である。
実施例１、２、３では、焼戻し帯での鋼板加熱温度に基づく連続焼鈍設備の制御を「実施」した。
その結果、コイルの接続部において、焼戻し帯での鋼板加熱温度に基づいて、連続焼鈍設備を制御することで、接続部の製品であっても溶接部近傍を除いてほぼすべてが出荷可能と判定された。さらに、変態率測定装置で測定したオーステナイト分率に基づいて焼鈍温度を制御することでＴＳのばらつきがさらに改善した。 In contrast to these comparative examples, Example 1 shows the results of manufacturing a product from the above-mentioned material using the method for controlling steel sheet manufacturing equipment according to the present invention.
Example 3 is an example in which a transformation rate measuring device is installed downstream of the induction heating device of Example 1.
In Examples 1, 2, and 3, control of the continuous annealing equipment based on the steel sheet heating temperature in the tempering zone was "implemented."
As a result, it was determined that almost all products at the joints of the coils could be shipped, except for the vicinity of the welded parts, by controlling the continuous annealing equipment based on the steel plate heating temperature in the tempering zone. Furthermore, the TS variation was further improved by controlling the annealing temperature based on the austenite fraction measured by the transformation rate measuring device.

　Ｓ　　鋼板
　Ｘ　　鋼板搬送方向
　１　鋼板製造設備
　２　　ペイオフリール
　３　　ウエルダー
　４　　ルーパー
　５　　連続焼鈍設備
　　６　　予熱帯
　　７　　加熱帯
　　８　　均熱帯
　　１０　冷却帯
　　　１０Ａ　第１冷却帯
　　　１０Ｂ　第２冷却帯
　１１　焼鈍後熱処理設備（鋼板めっき設備）
　１２　　めっき浸漬帯
　１３　　めっき合金化帯
　１４　　保熱帯
　１５　　急速冷却帯
　１６　　焼戻し帯
　　１７　　焼戻し帯加熱装置
　　１８　　焼戻し帯保熱装置
　　１９　　焼戻し帯冷却装置
　２０　　温度測定装置
　２１　　変態率測定装置
　３０　管理装置
　　３１　　機械特性予測部
　　３２　　熱処理条件演算部
　　３３　　熱処理条件制御部
　　３４　　記憶部 S: Steel sheet; X: Steel sheet transport direction; 1: Steel sheet manufacturing equipment; 2: Payoff reel; 3: Welder; 4: Looper; 5: Continuous annealing equipment; 6: Preheating zone; 7: Heating zone; 8: Soaking zone; 10: Cooling zone; 10A: First cooling zone; 10B: Second cooling zone; 11: Post-annealing heat treatment equipment (steel sheet plating equipment);
REFERENCE SIGNS LIST 12 Plating immersion zone 13 Plating alloying zone 14 Holding zone 15 Rapid cooling zone 16 Tempering zone 17 Tempering zone heating device 18 Tempering zone heat retention device 19 Tempering zone cooling device 20 Temperature measuring device 21 Transformation rate measuring device 30 Management device 31 Mechanical property prediction unit 32 Heat treatment condition calculation unit 33 Heat treatment condition control unit 34 Memory unit

Claims (6)

鋼板搬送方向に、加熱帯と、均熱帯と、冷却帯と、をこの順で有する鋼板の連続焼鈍設備と、
前記冷却帯の前記鋼板搬送方向の下流に、少なくとも急速冷却帯と、焼戻し帯と、をこの順で有する焼鈍後熱処理設備と、
少なくとも前記均熱帯と前記焼戻し帯に設置される前記鋼板の温度測定装置と、
を備える鋼板製造設備における前記連続焼鈍設備での鋼板加熱温度の制御方法であって、
前記温度測定装置で測定した前記焼戻し帯での鋼板加熱温度に基づいて、前記鋼板の伸び値および穴広げ率を含む機械特性値を予測する機械特性予測ステップと、
該機械特性予測ステップで予測した前記機械特性値を前記鋼板の目標機械特性値に補正し、補正された前記機械特性値に基づいて熱処理条件を決定する熱処理条件演算ステップと、
該熱処理条件演算ステップで決定した熱処理条件に基づいて、前記連続焼鈍設備のうち、少なくとも前記均熱帯での鋼板加熱温度を制御する熱処理条件制御ステップと、
を含む、鋼板製造設備の制御方法。 A continuous annealing facility for steel sheets having a heating zone, a soaking zone, and a cooling zone in this order in a steel sheet transport direction;
A post-annealing heat treatment facility having at least a rapid cooling zone and a tempering zone in this order downstream of the cooling zone in the steel sheet transport direction;
Temperature measuring devices for the steel sheet are installed at least in the soaking zone and the tempering zone;
A method for controlling a steel sheet heating temperature in a continuous annealing facility in a steel sheet manufacturing facility comprising:
A mechanical property prediction step of predicting mechanical property values including an elongation value and a hole expansion ratio of the steel sheet based on the steel sheet heating temperature in the tempering zone measured by the temperature measuring device;
a heat treatment condition calculation step of correcting the mechanical property values predicted in the mechanical property prediction step to target mechanical property values of the steel sheet, and determining heat treatment conditions based on the corrected mechanical property values;
a heat treatment condition control step of controlling a steel sheet heating temperature in at least the soaking zone in the continuous annealing facility based on the heat treatment conditions determined in the heat treatment condition calculation step;
A method for controlling a steel plate manufacturing facility, comprising: 前記熱処理条件制御ステップにおいて、前記熱処理条件演算ステップで決定した熱処理条件に基づいて、前記均熱帯での鋼板加熱温度と、前記冷却帯での鋼板冷却条件とを制御する、請求項１に記載の鋼板製造設備の制御方法。 The method for controlling steel sheet manufacturing equipment according to claim 1, wherein in the heat treatment condition control step, the steel sheet heating temperature in the soaking zone and the steel sheet cooling conditions in the cooling zone are controlled based on the heat treatment conditions determined in the heat treatment condition calculation step. 前記鋼板製造設備において、前記鋼板搬送方向に、前記均熱帯出側から前記焼戻し帯出側までのうちの少なくとも１箇所で前記鋼板のオーステナイト分率を測定する変態率測定装置をさらに備え、
前記機械特性予測ステップでは、
前記温度測定装置で測定した前記焼戻し帯での鋼板加熱温度と、前記変態率測定装置で測定したオーステナイト分率とに基づいて、前記鋼板の機械特性値を予測する、請求項１または２に記載の鋼板製造設備の制御方法。 The steel sheet manufacturing facility further includes a transformation rate measuring device for measuring an austenite fraction of the steel sheet at at least one location from the soaking zone exit side to the tempering zone exit side in the steel sheet transport direction,
In the mechanical property prediction step,
3. The method for controlling steel sheet manufacturing equipment according to claim 1 or 2, further comprising predicting mechanical property values of the steel sheet based on the steel sheet heating temperature in the tempering zone measured by the temperature measuring device and the austenite fraction measured by the transformation ratio measuring device. 鋼板搬送方向に、加熱帯と、均熱帯と、冷却帯と、をこの順で有する鋼板の連続焼鈍設備と、
前記冷却帯の前記鋼板搬送方向の下流に、少なくとも急速冷却帯と、焼戻し帯と、をこの順で有する焼鈍後熱処理設備と、
少なくとも前記均熱帯と前記焼戻し帯に設置される前記鋼板の温度測定装置と、
を備える鋼板製造設備であって、
前記温度測定装置で測定した前記焼戻し帯での鋼板加熱温度に基づいて、前記鋼板の伸び値および穴広げ率を含む機械特性値を予測する機械特性予測部と、
該機械特性予測部で予測した前記機械特性値を前記鋼板の目標機械特性値に補正し、補正された前記機械特性値に基づいて熱処理条件を決定する熱処理条件演算部と、
該熱処理条件演算部で決定した熱処理条件に基づいて、前記連続焼鈍設備のうち、少なくとも前記均熱帯での鋼板加熱温度を制御する熱処理条件制御部と、
をさらに備える、鋼板製造設備。 A continuous annealing facility for steel sheets having a heating zone, a soaking zone, and a cooling zone in this order in a steel sheet transport direction;
A post-annealing heat treatment facility having at least a rapid cooling zone and a tempering zone in this order downstream of the cooling zone in the steel sheet transport direction;
Temperature measuring devices for the steel sheet are installed at least in the soaking zone and the tempering zone;
A steel sheet manufacturing facility comprising:
A mechanical property prediction unit that predicts mechanical property values including an elongation value and a hole expansion ratio of the steel sheet based on the steel sheet heating temperature in the tempering zone measured by the temperature measuring device;
a heat treatment condition calculation unit that corrects the mechanical property values predicted by the mechanical property prediction unit to target mechanical property values of the steel sheet and determines heat treatment conditions based on the corrected mechanical property values; and
a heat treatment condition control unit that controls a steel sheet heating temperature in at least the soaking zone in the continuous annealing facility based on the heat treatment conditions determined by the heat treatment condition calculation unit;
The steel plate manufacturing facility further comprises: 前記熱処理条件制御部において、前記熱処理条件演算部で決定した熱処理条件に基づいて、前記均熱帯での鋼板加熱温度と、前記冷却帯での鋼板冷却条件とを制御する、請求項４に記載の鋼板製造設備。 The steel sheet manufacturing equipment according to claim 4, wherein the heat treatment condition control unit controls the steel sheet heating temperature in the soaking zone and the steel sheet cooling conditions in the cooling zone based on the heat treatment conditions determined by the heat treatment condition calculation unit. 前記鋼板搬送方向に、前記均熱帯出側から前記焼戻し帯出側までのうち少なくとも１箇所で前記鋼板のオーステナイト分率を測定する変態率測定装置を備え、
前記機械特性予測部では、
前記温度測定装置で測定した前記焼戻し帯での鋼板加熱温度と、前記変態率測定装置で測定したオーステナイト分率とに基づいて、前記鋼板の機械特性値を予測する、請求項４または５に記載の鋼板製造設備。
 

  a transformation rate measuring device for measuring an austenite fraction of the steel sheet at at least one location from an outlet side of the soaking zone to an outlet side of the tempering zone in the steel sheet transport direction,
In the mechanical property prediction unit,
6. The steel sheet manufacturing facility according to claim 4 or 5, wherein mechanical property values of the steel sheet are predicted based on the steel sheet heating temperature in the tempering zone measured by the temperature measuring device and the austenite fraction measured by the transformation ratio measuring device.
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