JP2008254060A - Method of deciding rolling order in hot rolling and method of manufacturing hot-rolled steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of deciding a rolling order in hot rolling by which a fuel cost for heating is reduced by controlling the heating of a rolled stock in a heating furnace by correctly predicting the amount of over-heating of the rolled stock in the heating furnace without using a complicated method, and a method of manufacturing the steel sheet by using the method. <P>SOLUTION: This method for deciding the rolling order of a plurality of rolled stocks which are rolled with a rolling mill after being heated in the heating furnace and the rolling order of the rolled stock includes: predicting discharging temperature from the heating furnace for each of the respective rolled stocks before the plurality of rolled stocks are charged into the heating furnace; calculating the amount of over-heating which is a difference between the predicted discharging temperature from the heating furnace and the target discharging temperature from the heating furnace; and calculating the evaluation function value of from the evaluation function containing the sum total of the amount of the over-heating of the plurality of the rolled stocks in at least one term, so that the evaluation function value of a becomes minimum. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for determining a rolling order of hot rolling in which a plurality of rolled materials are heated in a heating furnace and then rolled with a rolling mill, and thereby a method for producing a hot-rolled steel sheet.

  In hot rolling, a rolled material is heated by a heating furnace before rolling the rolled material (slab) with a rolling mill. The degree to which the rolled material is heated in this heating furnace is determined from the viewpoint of rolling stability and obtaining desired mechanical properties, from the target heating furnace extraction temperature (the target temperature of the rolled material at the outlet of the heating furnace. The same applies hereinafter. .) Is determined for each rolled material. However, the heating furnace does not individually heat each rolled material, and since a plurality of rolled materials are charged, it is not possible to individually heat each rolled material to the target heating furnace extraction temperature. . If the heating furnace extraction temperature is higher than the target, the temperature can be adjusted by air cooling or water cooling before rolling, but if the temperature is lower than the target, it is difficult to raise the temperature, and rolling may cause rolling trouble if it is rolled as it is. The desired mechanical properties cannot be obtained and must be avoided. Therefore, normally, the furnace temperature is set so that none of the rolled material charged in the heating furnace is less than the target heating furnace extraction temperature. However, when a rolled material with a low target heating furnace extraction temperature is sandwiched between rolled materials with a high target temperature and inserted into the heating furnace, even a rolled material with a low target heating furnace extraction temperature is set to a high temperature. When heated, the fuel was overheated, and the fuel cost sometimes deteriorated.

In order to avoid this, Patent Document 1 discloses a technique relating to rolling schedule determination. According to this, the above-mentioned problem is solved by determining the rolling order so that the target heating furnace extraction temperature is smoothly aligned when viewed in the charging order (that is, the rolling order in the rolling material charged in the same heating furnace). It is to do. Patent Document 2 discloses that the charging furnace is determined so that the heating furnace fuel flow rate is small.
JP-A-63-53215 JP-A-6-304619

  However, the technique relating to the rolling schedule determination described in Patent Literature 1 does not clarify how smoothness should be achieved. It is considered that the rolling materials are arranged so that the target heating furnace extraction temperature charged in the same heating furnace changes monotonously in the rolling order. However, the same rolling chance (corresponding to determining the timing for changing the rolling tool so that defective products do not occur due to the rough surface of the rolling tool by continuing rolling, and until the next rolling tool change is called one rolling opportunity. The same applies hereinafter.) In addition, there are other rolling restrictions such as rolling from a wide rolled material to a narrow rolled material, and the rolled material is simply monotonous from the viewpoint of the target heating furnace extraction temperature. It is impossible in actual operation to line up. In other words, when determining the rolling order, if the sheet width and thickness should be taken into consideration and neglecting this, the rolled material is monotonically arranged from the viewpoint of only the target heating furnace extraction temperature. Since various troubles such as poor penetration and poor winding occur, it is practically impossible to perform rolling in such a smooth arrangement from the viewpoint of temperature alone.

  In the rolling order determination method described in Patent Document 2, first, from the viewpoint of ease of rolling, the rolling order is determined so as to satisfy the rolling constraint matrix and reduce the rolling evaluation value. Then, the charging furnace is determined so that the heating furnace fuel flow rate is small. That is, since the charging furnace is selected on the premise that the rolling order determined in the first stage is maintained from the ease of rolling, the effect of reducing the fuel flow rate is small.

  Further, when determining the rolling order of the rolled material, one parameter for determining the rolling order can be obtained if the heating furnace extraction temperature can be predicted. However, until now, there has been no means for accurately finding the best order by combining a myriad of rolling orders within a limited time of determining the rolling order. In order to find the optimum furnace extraction temperature, for example, solving the heat transfer equation for each combination of rolling orders is unrealistic due to the limitations of resources and time required for that purpose.

  Therefore, the present invention controls the heating of the rolling material in the heating furnace by accurately predicting the overheating amount of the rolling material in the heating furnace without using a complicated method, and can reduce the heating fuel cost in the rolling order. It is an object of the present invention to provide a determination method, a method for producing a hot-rolled steel sheet by the method, and an apparatus therefor.

  As a result of intensive studies, the inventors predicted the extraction temperature from the heating furnace before the rolled material is charged into the heating furnace, and the difference between the predicted heating furnace extraction temperature and the target heating furnace extraction temperature. It was found that the energy required for heating can be suppressed by obtaining an overheating amount and introducing an evaluation function based thereon. The inventors have developed these findings and completed the present invention. The present invention will be described below.

  The invention according to claim 1 is a method for determining a rolling order of a plurality of rolled materials that are rolled in a rolling mill after being heated in a heating furnace, and before the plurality of rolled materials are charged into the heating furnace. Predict the heating furnace extraction temperature for each of the rolled materials, calculate an overheating amount that is the difference between the predicted heating furnace extraction temperature and the target heating furnace extraction temperature of the rolled material, An evaluation function value is calculated from an evaluation function including the sum of heating amounts in at least one term, and the rolling order of the rolled material is determined so that the evaluation function value is minimized. The problem is solved by providing a determination method.

  Here, the term “minimum” refers to a method such as heuristic search, which is a heuristic method, for example, when it is impossible to obtain a true minimum value due to time constraints, in addition to being truly minimum. It shall include the calculated subminimum. The same applies hereinafter.

  In the invention according to claim 2, when a plurality of direct feed materials that are rolled materials directly fed from a casting process and a plurality of non-direct feed materials that are rolled materials other than the direct feed materials are mixed and rolled, A heating furnace that heats only the material, and a heating furnace that heats only the non-direct feed material, and determines the rolling order of the direct feed material and the non-direct feed material, the direct feed material from the casting process to the heating furnace Calculate the total time by adding the required heating time in the heating furnace to the required transport time, and assign it to be in the rolling order that can be rolled earliest after the total time. Non-direct feed materials are heated by multiple non-direct feed materials. Predict the heating furnace extraction temperature for each of the non-direct feed materials before charging into the furnace, and calculate the amount of overheating that is the difference between the predicted heating furnace extraction temperature and the target heating furnace extraction temperature of the non-direct feed material In addition, at least one sum of the amount of overheating of a plurality of non-direct feed materials By calculating the evaluation function value from the evaluation function included in the term, and determining the rolling order of the non-direct feed material so as to minimize the evaluation function value, by providing a rolling order determination method for hot rolling The problem is solved.

  Here, “required transport time” means the shortest time required from the end of the casting process to charging into the heating furnace, and “required heating time” refers to after being charged into the heating furnace. , Means the shortest time required to heat to the target furnace extraction temperature.

  The invention according to claim 3 can calculate the predicted heating furnace extraction temperature of the hot rolling rolling order determination method according to claim 1 or 2 from only the rolling order and the target heating furnace extraction temperature. After calculating one evaluation function value by giving one rolling order, another evaluation function value is calculated by giving another rolling order different from one rolling order, and one evaluation function When the value is less than or equal to another evaluation function value, the one evaluation function value is maintained as it is, and when the other evaluation function value is smaller than one evaluation function value, the one evaluation function value becomes another evaluation function value. The problem is solved by providing a method for determining the rolling order of hot rolling, wherein the evaluation function value is minimized by repeating the replacement process.

  Invention of Claim 4 performs the rolling order obtained by the rolling order determination method of the hot rolling as described in any one of Claims 1-3, The manufacturing method of the hot-rolled steel plate characterized by the above-mentioned The above-described problem is solved.

  Invention of Claim 5 provides the rolling order determination apparatus characterized by including the means to calculate a rolling order by the rolling order determination method of the hot rolling as described in any one of Claims 1-3. This solves the problem.

  Invention of Claim 6 is a manufacturing apparatus of the hot-rolled steel plate which has a heating furnace and a rolling mill, Comprising: The manufacturing order of the hot-rolled steel plate provided with the rolling order determination apparatus of Claim 5 characterized by the above-mentioned. The problem is solved by providing an apparatus.

  According to the method for determining the rolling order of hot rolling and the method for manufacturing a hot-rolled steel sheet according to the present invention, it is possible to accurately predict the amount of overheating in the heating furnace of the rolled material, and thereby the rolling material in the heating furnace. It is possible to control the heating and reduce the heating fuel cost.

  Moreover, the temperature prediction of the predicted heating furnace extraction temperature is calculated from only the rolling order and the target heating furnace extraction temperature, so that the temperature prediction that has not been possible due to time and resource constraints has been complicated. You can do it without having to.

  In addition, the rolling order determining apparatus having means capable of executing such a rolling order determining method, and the hot rolled steel sheet manufacturing apparatus having the rolling order determining apparatus, perform actual rolling in the calculated rolling order. be able to.

  Such an operation and gain of the present invention will be made clear from the best mode for carrying out the invention described below.

  FIG. 1 is a diagram showing a flow of a rolling order determination method S0 of the present invention according to one embodiment. The rolling order determination method S0 is a method for determining the rolling order of the rolled material charged in a predetermined heating furnace. Here, the evaluation function value J is introduced in the rolling order determination method S0 of the present invention. And the condition where the said evaluation function value J takes the minimum value is obtained, and a rolling order is determined by this. Therefore, the evaluation function value J will be described first, and then the rolling order determination method S0 will be described.

  The evaluation function value J according to one example is

で表され、３つの項の和で構成されている。ここでＪ_ｔは過加熱量総和の評価項、Ｊ_ｗは仕上げ板幅の評価関数項、及びＪ_ｈは仕上げ板厚の評価関数項である。以下それぞれについて説明する。
＜過加熱量総和の評価項Ｊ_ｔ＞
過加熱量総和の評価項Ｊ_ｔは、全ての圧延材の過加熱量（予測加熱炉抽出温度と、その圧延材の目標加熱炉抽出温度との差）の和である。従って、過加熱量総和の評価項Ｊ_ｔは、

It is composed of the sum of three terms. Here J _t is overheating amount sum of evaluating terms, J _w evaluation function term of finishing strip width, and J _h is the evaluation function section of the finished plate thickness. Each will be described below.
<Evaluation term J _{t of} total overheating amount>
Evaluating terms J _t of overheating amount sum is the sum of the overheating of all the rolled material (the difference between the predicted heating furnace extraction temperature, the target heating furnace extraction temperature of the rolled material). Therefore, the evaluation term J _{t of the} total amount of overheating is

で表される。ここで、Ｔ_ｊは第ｊ圧延材における予測抽出温度、Ｔ_{ａｉｍ，ｊ}は目標抽出温度である。従ってこの２つの温度の差が過加熱量である。またα_ｔは重み係数であり、当該圧延に関して、この項をＪの値に対してどの程度影響させるかを示すものである。そしてこれは圧延の目的、効率等の観点から、熱延鋼板の製造の事情に応じて都度設定される。

It is represented by Here, T _j is the predicted extraction temperature in the j-th rolled material, and T _{aim, j} is the target extraction temperature. Therefore, the difference between the two temperatures is the amount of overheating. In addition, α _t is a weighting factor and indicates how much this term affects the value of J with respect to the rolling. And this is set each time according to the circumstances of the production of the hot-rolled steel sheet from the viewpoint of rolling purpose, efficiency and the like.

As described above, the evaluation term J _{t of the} total amount of overheating includes the predicted extraction temperature T _j in the j-th rolled material. Then, the prediction method of the said prediction extraction temperature Tj is _demonstrated next. The figure used for description is shown in FIG. Will be described here to determine the predicted extraction temperature T _i of the i rolled material in the context of the seven of the rolled material in the same furnace zone resides. Here, the “same furnace zone” refers to an area in the heating furnace, in which any position in the furnace zone has the same temperature condition, and individual temperature setting by position is not possible. FIG. 2 (a) shows that when the i-th rolled material is charged into the furnace zone surrounded by a broken line ((1)), the furnace zone is advanced ((2) to (7)). The situation up to the time of leaving ((8)) is schematically shown. FIG. 2 (b) shows the set temperature in the furnace zone from when the i-th rolled material is charged to the furnace zone until it is extracted, with the horizontal axis representing time and the vertical axis representing temperature. . As can be seen from FIGS. 2 (a) and 2 (b), when the i-th rolled material is charged into the furnace zone, there are six rolled materials i-6 to i-1 rolled material before that. It is in the same furnace zone (Fig. 2 (a) (1)). The set temperature of the furnace zone at this time is θ _i-6 , which is a temperature for extracting the i-6th rolled material at a predetermined extraction temperature, as can be seen from FIG. This temperature is maintained for Δt _i-6 , which is the time until the i-6th rolled material is extracted. As the i-th rolled material travels through the furnace zone, the i-5 likewise temperature in until the strip, second i rolled theta _i-5 through? _I is set, the time Δt _i-5 ~Δt _i respectively Maintained.

  Next, a value represented by the product of time and temperature is introduced, and the hatched portion in FIG.

一方、予測抽出温度Ｔ_ｉは、図２（ｂ）に示した温度履歴を経て得られる温度であるから、予測抽出温度Ｔ_ｉと第ｉ圧延材が炉帯内に存する時間との積は、式３と釣り合うはずである。従って、予測抽出温度Ｔ_ｉを用いて式４を得て、ここから式５を導くことができる。

On the other hand, since the predicted extraction temperature T _i is a temperature obtained through the temperature history shown in FIG. 2B, the product of the predicted extraction temperature T _i and the time that the i-th rolled material exists in the furnace zone is Should be balanced with Equation 3. Therefore, Equation 4 can be obtained using the predicted extraction temperature T _i , and Equation 5 can be derived therefrom.

Thus it is possible to obtain the predicted extraction temperature T _i. However, the predicted extraction temperature T _i needs to be at least the target extraction temperature T _{aim, i of} the i-th rolled material. Therefore, a condition is set for the set temperature θ _j considering this. Details are as follows. FIG. 3 shows a view corresponding to FIG. 2B in the state of FIGS. That is, before the portion indicated by the solid line N in FIG. 3, the i-th rolled material has already been heated as indicated by the oblique lines, and thereafter is not determined. A method of setting θ _{i-3 in} this case will be described in detail. With regard to FIG. 3, focusing on the i-th rolled material, Equation 6 corresponding to Equation 4 above can be obtained with T _i being T _{aim, i} .

式６において、右辺第２項がこれから加熱される部分を表しているので、式６を変形して式７を得る。

In Expression 6, since the second term on the right side represents a portion to be heated from now on, Expression 6 is modified to obtain Expression 7.

ここで、図３にＮで示した時点以降の設定温度を第ｉ圧延材が抽出されるまで一定であると仮定しこれをζ_ｉとすると、式７から式８、及び式９を得ることができる。

Here, assuming that the set temperature after the time indicated by N in FIG. 3 is constant until the i-th rolled material is extracted and this is set as ζ _i , Equations 7 to 8 and 9 are obtained. Can do.

  In the state of FIGS. 2 (a) and (4), the same applies to the rolled material (preceding rolled material: i-3 to i-1 and subsequent rolled material: i + 1 to i + 3) in the same furnace zone. Since a condition for the extraction temperature to be equal to or higher than the target extraction temperature is obtained, Equation 10 is obtained that collectively represents these conditions.

ここで、「ｋ＝ｉ−３〜ｉ＋３」である。

Here, “k = i−3 to i + 3”.

  Therefore, in the state of FIGS. 2A and 2, Expression 11 is obtained as a condition for all the extraction temperatures of the rolled material (i−3 to i + 3) in the same furnace zone to be equal to or higher than the target extraction temperature. .

これら式１０及び式１１を式５に代入することにより、同一炉帯に装入された圧延材の全てが目標抽出温度未満にならないことが考慮された予測抽出温度Ｔ_ｉを求めることが可能となる。

By substituting these expressions 10 and Formula 11 to Formula 5, it is possible that all of the rolled material which is charged to the same reactor zone obtain the prediction extraction temperatures T _i which may not fall below the target extraction temperature were considered Become.

  Thus, the predicted extraction temperature can be obtained only from the rolling order and the target extraction temperature. In practice, the extraction temperature varies slightly depending on the specific heat, thermal conductivity, dimensions of the rolled material, etc., but the influence of the rolling order, which is the problem to be solved by the present invention, that is, it exists in the same furnace zone of the heating furnace. The phenomenon that the extraction temperature becomes higher than the target extraction temperature due to the difference in the target extraction temperature of the rolled material to be performed can be completely predicted by the above method. In addition, it is possible to significantly reduce the time compared to obtaining the predicted extraction temperature by calculating the heat transfer equation, so it can be incorporated into a scheduling problem that requires repeated calculations to obtain the optimal solution. it can.

<Evaluation function term J _w of finished plate width>
Evaluation function terms J _w finishing strip width is a function section for evaluating the change with respect to the plate width of the finishing rolling in the rolling member to the front-rear, finishing strip width of the rolling material is variable. The ideal is that within one rolling opportunity, the sheet width of the rolled material that is always rolled later is narrower than the sheet width of the rolled material that is rolled before that. However, since this is not necessarily ideal due to the influence of other conditions, it is evaluated by the finished plate width evaluation function term _Jw . J _w is expressed by Equation 12.

ここで、ｆ（Ｗ_ｊ，Ｗ_ｊ−１）は第ｊ圧延材における評価関数であり、圧延機の特性、製造ラインの性質等により得られる関数である。またα_ｗは重み係数であり、当該圧延に関して、この項をＪの値に対してどの程度影響させるかを示すものである。そしてこれは圧延の目的、効率等の観点から、熱延鋼板の製造の事情に応じて都度設定される。

Here, f (W _j , W _j−1 ) is an evaluation function in the j-th rolled material, and is a function obtained by the characteristics of the rolling mill, the properties of the production line, and the like. _Αw is a weighting factor, and indicates how much this term affects the value of J with respect to the rolling. And this is set each time according to the circumstances of the production of the hot-rolled steel sheet from the viewpoint of rolling purpose, efficiency and the like.

Specifically, f (W _j , W _j−1 ) is a function having properties as shown in FIG. In FIG. 4, the horizontal axis represents the difference in the finished plate width of the pre-rolled material, and the vertical axis represents f (W _j , W _j−1 ). Thus, the function f (W _j , W _j−1 ) takes the minimum value when the finished sheet width difference between the preceding and subsequent rolled materials is zero. And when the plate width of the steel plate to be rolled later becomes larger than the plate width of the steel plate to be rolled first, f (W _j , W _j-1 ) also becomes large according to the degree of increase. On the other hand, when the plate width of the steel plate to be rolled later is smaller than the plate width of the steel plate to be rolled first, f (W _j , W _j-1 ) increases gradually and exceeds a predetermined value. It grows rapidly.

<Finished plate thickness evaluation function term _Jh >
Evaluation function terms J _h finishing thickness is in the section to evaluate the change with respect to the thickness of the finishing rolling between the front-rear rolled material, finish thickness of the rolled material is variable. The ideal is that all the steel plates to be rolled have the same thickness within one rolling opportunity. However, since this is not always ideal due to the influence of other conditions, and evaluated it by the finish thickness evaluation function section J _h, the formula 13.

ここで、ｇ（ｈ_ｊ，ｈ_ｊ−１）は第ｊ圧延材の厚みに関する評価関数であり、圧延機の特性、製造ライン性質等により得られる関数である。またα_ｈは重み係数であり、当該圧延に関して、この項をＪの値に対してどの程度影響させるかを示すものである。そしてこれは圧延の目的、効率等の観点から、熱延鋼板の製造の事情に応じて都度設定される。

Here, g (h _j , h _j-1 ) is an evaluation function related to the thickness of the j-th rolled material, and is a function obtained from the characteristics of the rolling mill, the production line properties, and the like. Α _h is a weighting coefficient, and indicates how much this term affects the value of J with respect to the rolling. And this is set each time according to the circumstances of the production of the hot-rolled steel sheet from the viewpoint of rolling purpose, efficiency and the like.

Specifically, g (h _j , h _j−1 ) is a function having properties as shown in FIG. In FIG. 5, the horizontal axis represents the difference in the finished sheet thickness of the pre-rolled material, and the vertical axis represents g (h _j , h _j−1 ). As described above, the function g (h _j , h _j−1 ) takes the minimum value when the finished sheet thickness difference between the preceding and subsequent rolled materials is zero. And when the plate | board thickness of the steel plate rolled later becomes thicker than the plate | board thickness of the steel plate rolled previously, g ( _hj , _hj-1 ) will also become large according to the degree to which it becomes large. On the other hand, when the plate thickness of the steel plate to be rolled later becomes thinner than the plate thickness of the steel plate to be rolled first, g (h _j , h _j-1 ) becomes larger at a larger rate.

The evaluation function value J can be obtained from Equation 1 where J _t , J _w , and J _h described above are terms. In the present embodiment, the evaluation function value J is obtained from the sum of the three terms, but other terms may be added or modified as long as the evaluation term _Jt includes the total overheating amount evaluation term Jt. May be. Which term is used can be selected depending on the purpose of rolling and the properties (dimensional accuracy and mechanical properties) of the rolled material to be obtained.

  Next, the rolling order determination method S0 will be described with reference to FIG. FIG. 1 shows the flow of the rolling order determination method S0. In the rolling order determination method S0, regarding the four heating furnaces of No. 1 to No. 4, the No. 1 and No. 2 furnaces heat non-direct feed materials (meaning that they are not direct feed materials from the casting process; the same applies hereinafter). No. 3 and No. 4 furnaces are embodiments in which direct feed materials (meaning direct feed materials from the casting process; the same applies hereinafter) are heated. The rolling order determination method S0 of this embodiment includes a step S1 for inputting rolled material information, a step S2 for determining the number of rolling opportunities and the number of rolled materials for each chance, a step S3 for calculating a heating furnace extraction time, and rolling of a direct feed material. Step S4 for determining the order and the charging furnace, Step S5 for determining the charging furnace corresponding to the rolling order of the non-direct feed material, and Step S6 for determining the rolling order of the non-direct feed material. Hereinafter, each step will be described.

<Step S1 for inputting rolled material information>
Step S1 for inputting rolled material information (hereinafter sometimes referred to as “step S1”) is a step for inputting information on a rolled material to be rolled. Here, each piece of information regarding the rolled material is input and transferred to the subsequent process. The input information can include, for example, direct feed material or non-direct feed material, target extraction temperature, finishing width, finishing thickness, and the like.

<Step S2 for determining the number of rolling chances and the number of rolled materials for each chance>
In step S2 for determining the number of rolling chances and the number of rolling materials for each opportunity (hereinafter sometimes referred to as “step S2”), the rolling material is divided into several rolling opportunities, and the number of rolling chances and each chance are configured. This is a step of determining the number of rolled materials to be rolled. The number of rolling chances and the number of rolling materials constituting each chance are determined empirically from the past surface roughness of the rolling tool.

<Process S3 for calculating heating furnace extraction time>
In step S3 for calculating the heating furnace extraction time (hereinafter sometimes referred to as “step S3”), the extraction time of the rolled material from the heating furnace is calculated. Here, a time obtained by adding the average extraction pitch to the heating furnace extraction time of the rolled material preceding the previous one is defined as the heating furnace extraction time. However, when the rolling chances of the rolled material preceding the preceding one and the rolled material are different, a rolling tool change time is added instead of the average extraction pitch.

<Step S4 for Determining Rolling Order and Charging Furnace of Direct Feed Material>
The step S4 for determining the rolling order of the direct feed material and the charging furnace (hereinafter sometimes referred to as “step S4”) is a step of determining the rolling order of the direct feed material and the heating furnace to be charged. The direct feed material has the highest priority on avoiding heat loss, and the required heating time is added to the time directly fed from the casting process to obtain the extractable time, and the latest rolling order is assigned after the extractable time. FIG. 6 schematically shows a scene where direct feed materials are assigned. In this way, the direct feed materials are allocated among the non-direct feed materials so as to have the most suitable rolling order. The heating furnace in which the direct feed material is charged is either the No. 3 furnace or the No. 4 furnace as described above, and the furnace to be charged is a heating furnace different from the preceding direct feed material. As a result, the direct feed material is cyclically charged into the No. 3 and No. 4 furnaces. By this step S4, the rolling order of the direct feed material and the charging furnace are determined.

<Step S5 of determining a charging furnace for non-direct feed materials>
Step S5 for determining the charging furnace for non-directly fed materials (hereinafter sometimes referred to as “step S5”) is a step for determining a heating furnace for charging each non-directly fed material according to the rolling order. As shown schematically in FIG. 7, the charging furnace is cyclically assigned to either the No. 1 furnace or No. 2 furnace so as to be a heating furnace different from the preceding non-direct feed material.

<Step S6 for determining the rolling order of non-direct feed materials>
The step S6 for determining the rolling order of the non-directly fed material (hereinafter, sometimes referred to as “step S6”) is a step for determining the rolling order of the non-directly fed material. The determination of the rolling order is performed in a predetermined order. 8 shows the flow of step S10 that is included in step S6 and calculates the minimum of the evaluation function value J to determine the rolling order of the non-directly fed material, which is the above-described evaluation function value J. In step S10, an evaluation function value J ′ is calculated based on the changed rolling order candidate of the non-directly fed material. Step S12 for performing comparison, Step S13 for comparing and determining evaluation function values, Step S14 for changing the rolling order to a rolling order candidate and setting the value of J ′ to J, and Step S15 for determining the end of calculation are included. The process will be described.

<Step S11 in which an evaluation function value J is calculated by giving a rolling order initial value of a non-direct feed material>
The step S11 for giving the initial value in the rolling order of the non-directly fed material and calculating the evaluation function value J (hereinafter sometimes simply referred to as “step S11”) is based on the appropriately determined initial rolling order of the non-directly fed material. This is a step of obtaining the evaluation function value J. Here, it has the objective of providing an initial value for performing calculation of each process described below.

<Step S12 of calculating the evaluation function value J ′ from the rolling order candidate in which the non-direct feed material is changed>
Step S12 for calculating the evaluation function value J ′ based on the rolling order candidate with the non-directly fed material changed (hereinafter sometimes simply referred to as “step S12”) is the rolling order that is the basis of the calculation in step S11. This is a step of setting the rolling order of different non-direct feed materials and calculating the evaluation function value J ′ based on this. The calculation method is as described above. As a result, two evaluation function values, that is, the evaluation function value J obtained in step S11 and the evaluation function value J ′ obtained in step S12 can be obtained.

<Step S13 for comparing and determining evaluation function values>
Step S13 for comparing and determining evaluation function values (hereinafter sometimes simply referred to as “step S13”) is a step of comparing the magnitudes of evaluation function value J and evaluation function value J ′. When the evaluation function value J is equal to or less than the evaluation function value J ′, the process S14, which will be described later, is changed to the rolling order candidate and the value of J ′ is set to J is skipped, and the calculation ends with the evaluation function value J. It progresses to process S15 to determine. On the other hand, if the evaluation function value J ′ is smaller, the rolling order is changed to a rolling order candidate and the process proceeds to step S14 where the value of J ′ is J. That is, here, it is determined that a smaller evaluation function value is selected.

<Step S14 in which the rolling order is changed to a rolling order candidate and the value of J ′ is J>
In step S14 where the rolling order is changed to a rolling order candidate and the value of J ′ is J (hereinafter, sometimes simply referred to as “step S14”), the evaluation function value J ′ is smaller in step S13. In this case, the evaluation function value J ′ is replaced with the evaluation function value J. Thereby, the minimum evaluation function value that can be taken at the present time can be set as the evaluation function value J.

<Step S15 for determining the end of calculation>
Here, it is a step of judging whether or not the further calculation of the evaluation function value J is finished and the result is reflected in the actual rolling order. The end of the calculation is when the rolling order that would normally yield the smallest evaluation function value J is found. However, in reality, the rolling order candidates are enormous, and it is difficult to find the minimum evaluation function value J strictly because of time constraints and the like. Therefore, the smallest evaluation function value among the predetermined number of evaluation function value calculations is adopted. Step S15 for determining the end of the calculation is a step for determining whether or not this calculation has reached a predetermined number of times. When the calculation has not reached the predetermined number of times, the process returns to step S12 to instruct to calculate a new evaluation function value J ′. On the other hand, when the calculation reaches a predetermined number of times, the process is terminated, and the rolling order in which the smallest evaluation function value J is obtained is adopted. Here, the setting method for the predetermined number of times is not particularly limited, but is determined based on the capacity of the computer and the time allowed for determining the rolling order.

  By the rolling order determination method S0 as described above, even when there are a plurality of heating furnaces and direct feed materials, the amount of overheating in the heating furnace of the rolling material is accurately predicted to heat the rolling material in the heating furnace. Controlling and heating fuel cost can be reduced. Here, the number of heating furnaces and the presence / absence of a direct feed material are not particularly limited, and in any case, the method of the present invention can be used. And the manufacturing method of a hot-rolled steel plate provided with this method can be provided by rolling in the rolling order obtained by this method.

  The actual production of a hot-rolled steel sheet is performed by using a rolling order determining apparatus provided with means for calculating the rolling order by the rolling order determining method of the present invention, and a hot-rolled steel sheet manufacturing apparatus having the rolling order determining apparatus.

  Next, the embodiment will be described in more detail. However, the present invention is not limited to this embodiment. In this example, the average overheating amount of the non-direct feed material was calculated based on the rolling order determination method S0 of the above-described embodiment. For comparison, the average overheating amount in the rolling order obtained by the conventional method is also shown.

  The conditions of the examples are based on the rolling order determination method S0 of the embodiment. That is, the non-direct feed material is charged into the No. 1 and No. 2 furnaces among the No. 1 to No. 4 furnaces. The amount of overheating is an average value of the amount of overheating in the No. 1 furnace and No. 2 furnace. In the conventional method, an evaluation function value K different from the evaluation function value J described in the present invention is used. Specifically, it is expressed by Expression 14.

ここで、Ｋ_ｔは抽出温度の評価項、Ｋ_ｗは仕上げ板幅の評価関数項、及びＫ_ｈは仕上げ板厚の評価関数項である。Ｋ_ｗはＪ_ｗと同じであり、Ｋ_ｈはＪ_ｈと同じである。また、Ｋ_ｔは式１５で表され、先後圧延材間における目標抽出温度に関してその変化を評価する項である。最も理想的には１つの圧延チャンス内で、目標抽出温度が上昇又は下降するいずれかの方向に単調に推移するように滑らかに圧延材の順が決められる。しかし、他の条件の影響によりこれが必ずしも理想的なものにはならないので、抽出温度の評価項Ｋ_ｔによりそれを評価するというものである。

Here, K _t is an evaluation term for the extraction temperature, K _w is an evaluation function term for the finished plate width, and K _h is an evaluation function term for the finished plate thickness. K _w is the same as the _{J w, K h} is the same as the _{J h.} K _t is expressed by Expression 15 and is a term for evaluating the change with respect to the target extraction temperature between the first and second rolled materials. Most ideally, the order of the rolled materials is determined smoothly so that the target extraction temperature changes monotonously in either direction of increasing or decreasing within one rolling chance. However, since thereby the influence of the other conditions are not always ideal, is that evaluates it by evaluating terms K _t of extraction temperature.

ここでτ_１，ｊは、１号炉に装入される第ｊ圧延材の目標抽出温度、τ_２，ｊは２号炉に装入される第ｊ圧延材の目標抽出温度である。すなわち抽出温度の評価項Ｋ_ｔでは同一炉内で先後する圧延材の目標抽出温度の差の２乗和を用いている。この際、本発明の方法と従来方法で、板幅、板厚に関する評価が同等、すなわちＪ_ｗ＝Ｋ_ｗ、Ｊ_h＝Ｋ_hとなるように重み係数α_ｗ，α_ｈを調整し、過加熱量に関する評価を比較した。

Here, τ _{1, j} is the target extraction temperature of the j-th rolled material charged into the No. 1 furnace, and τ _{2, j} is the target extraction temperature of the j-th rolled material charged into the No. 2 furnace. That is, in evaluating terms K _t of extraction temperatures are used the sum of squares of the difference of the target extraction temperature of the strip to the front-rear in the same furnace. At this time, the weighting factors α _w and α _h are adjusted so that the evaluations regarding the plate width and thickness are equal between the method of the present invention and the conventional method, that is, J _w = K _w and J _h = K _h. The evaluation regarding the heating amount was compared.

  Table 1 shows the results.

  Thus, the amount of overheating was able to be suppressed by heating a rolling material by the rolling order determined by this invention. As a result, a heat amount of 1.7 kcal (7.1 kJ) per 1 kg of the rolled material can be saved, and the fuel corresponding to this can be reduced.

  Although the present invention has been described in connection with the most practical and preferred embodiments at the present time, the present invention is not limited to the embodiments disclosed herein, The invention can be changed as appropriate without departing from the scope or spirit of the invention that can be read from the claims and the entire specification, and includes such a change, a rolling order determination method, a method of manufacturing a hot-rolled steel sheet using the method, and The manufacturing apparatus must also be understood as being included in the technical scope of the present invention.

It is a flowchart of the rolling order determination method of the hot rolling of this invention which concerns on one embodiment. It is a figure for demonstrating the method of calculating | requiring estimated heating furnace extraction temperature. It is a further figure for demonstrating the method of calculating | requiring estimated heating furnace extraction temperature. It is a graph which shows typically the characteristic of the function in the evaluation term of finishing board width. It is a graph which shows typically the characteristic of the function in the evaluation term of finishing board thickness. It is the figure which showed typically the scene where the direct feed material was allocated. It is the figure which showed typically the scene where the non-direct feed material was allocated to the heating furnace. It is a flowchart of the process of calculating the evaluation function value J contained in the process of determining the rolling order of a non-direct feed material.

Explanation of symbols

S0 Rolling Order Determination Method for Hot Rolling S1 Step for Inputting Rolled Material Information S2 Step for Determining the Number of Rolling Opportunities and the Number of Rolled Materials for Each Opportunity S3 Step for Calculation of Heating Furnace Extraction Time S4 Rolling Order and Charging Step of determining heating furnace S5 Step of determining charging furnace corresponding to rolling order of non-directly fed material S6 Step of determining rolling order of non-directly fed material S10 Rolling of non-directly fed material by calculating minimum of evaluation function value J Step until order is determined S11 Step of calculating an evaluation function value J by giving an initial value in the rolling order of the non-directly fed material S12 Step of calculating an evaluation function value J ′ based on a rolling order candidate whose non-directly fed material is changed S13 Evaluation Step S14 for comparing and determining function values Step S15 for changing the rolling order to a rolling order candidate and setting the value of J 'to J S15 Step for determining the end of calculation S15

Claims (6)

A method for determining a rolling order of a plurality of rolled materials rolled in a rolling mill after being heated in a heating furnace,
Before a plurality of the rolled materials are charged into the heating furnace, a heating furnace extraction temperature is predicted for each of the rolled materials, and the predicted heating furnace extraction temperature and the target heating furnace extraction temperature of the rolling material are calculated. While calculating the amount of overheating that is the difference,
Calculating an evaluation function value from an evaluation function including the sum of the overheating amounts of the plurality of rolled materials in at least one term, and determining a rolling order of the rolled material so that the evaluation function value is minimized. A method for determining the rolling order of hot rolling. A heating furnace that heats only the direct feed material when mixing and rolling a plurality of direct feed materials that are rolled materials directly fed from a casting process and a plurality of non-direct feed materials that are rolled materials other than the direct feed materials, And a heating furnace for heating only the non-direct feed material, and determining a rolling order of the direct feed material and the non-direct feed material,
The direct feed material is calculated by adding the necessary heating time in the heating furnace to the necessary conveying time from the casting process to the heating furnace, and assigned so that the rolling order can be rolled earliest after the total time. And
The non-direct feed material predicts a heating furnace extraction temperature for each of the non-direct feed materials before the plurality of non-direct feed materials are charged into the heating furnace, and the predicted heating furnace extraction temperature and the non-direct feed material While calculating the amount of overheating that is the difference from the target furnace extraction temperature of
An evaluation function value is calculated from an evaluation function including the sum of the overheating amounts of a plurality of the non-direct feed materials in at least one term, and the rolling order of the non-direct feed materials is determined so that the evaluation function value is minimized. A method for determining the rolling order of hot rolling. The heating furnace extraction temperature predicted by the hot rolling rolling order determination method according to claim 1 or 2 is expressed by an expression that can be calculated only from the rolling order and the target heating furnace extraction temperature. After calculating one evaluation function value by giving the rolling order of, the other evaluation function value is calculated by giving another rolling order different from the one rolling order,
When the one evaluation function value is less than or equal to the other evaluation function value, the one evaluation function value is maintained as it is, and when the other evaluation function value is smaller than the one evaluation function value, the one evaluation function value Is a method for determining the rolling order of hot rolling, wherein the evaluation function value is minimized by repeating the process of replacing the other evaluation function values.   A method for producing a hot-rolled steel sheet, wherein rolling is performed in the rolling order obtained by the method for determining the rolling order of hot rolling according to any one of claims 1 to 3.   A rolling order determination apparatus comprising means for calculating a rolling order by the hot rolling rolling order determination method according to any one of claims 1 to 3.   An apparatus for producing a hot-rolled steel sheet having a heating furnace and a rolling mill, comprising the rolling order determining apparatus according to claim 5.

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