JPH07284827A - Method for scheduling physical distribution in rolling mill - Google Patents

Abstract

PURPOSE:To control the distribution of the rolled slab by determining the optimum rolling order in the hot rolling process and the optimum charging order in heating furnaces. CONSTITUTION:The furnace where the slab is charged, the heating order, and the rolling order in a rolling mill consisting of a plurality of heating furnaces and rolling mills are determined. The system consists of a slab data input part having the function where the attributes of the lab are inputted, a width sorting part to sort the attributes, a rolling constraint matrix calculating part to calculate the rolling conditions according to the attributes, a rolling order solution seeking part having the function to determine the rolling order, a heating furnace constraints calculating part to calculate the constraints to sort the slab whose rolling order is determined to each heating furnace, and a charging furnace solution seeking part having the function where the respective slabs are charged in an appropriate heating furnace to calculate the evaluation function, the optimum solution is sought to determine the charging furnace. An optimum heating furnace is determined while the evaluation variable is changed under the condition that the value of the evaluation variable not to be used in the seeking in the seeking process is not deteriorated over the prescribed numerical value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distribution system for a rolling process such as a hot rolling mill, and to a method for controlling the distribution of rolling slabs in the process.

[0002]

2. Description of the Related Art When determining the treatment order and treatment time in the hot rolling process of the slab carried from the upper process (continuous casting process or the slab yard placed after that), the slab steel type, width, There are many rolling restrictions and heating restrictions regarding attributes such as thickness and temperature, and they are arranged as many operation restrictions. Attempts have been made using AI technology to automatically determine the rolling sequence and charging furnace to comply with those rules, but at present it is still insufficient. Attempts have also been made to determine the rolling order from the attributes of two consecutive slabs.

Further, much of the slab charging and heating furnace is determined by a method based on the experience of the operator.

[0004]

SUMMARY OF THE INVENTION In such a conventional method, In order determination that considers only the attributes of two consecutive slabs (relative position constraint), the constraints on the rolling position of the slab are
(Absolute position constraint: Specified for rolling order after roll exchange for a slab) cannot be satisfied.

2. Consistency between heating furnace capacity and rolling mill capacity (matching extraction time from heating furnace with rolling pitch, rolling order and heating furnace charging order with fuel cost, and difficulty of rolling) is considered. There was a problem of not saying.

Japanese Patent Application No. 05-101005 filed previously
In this issue, when determining the rolling order, by considering not only the relative position constraint at the time of rolling until now, but also the absolute position constraint, a constraint condition expression regarding the heating capacity and an evaluation function regarding the required fuel are introduced. This solves the above problems, determines the rolling order, and then searches for the distribution of the heating furnace. However, in this method, when the heating furnace is distributed, the evaluation value is obtained by the extraction time and the sum of the loads of the required fuel, so it is difficult to set the respective weights, and in some cases it does not reach the optimum solution, Sometimes it just stayed at the optimal solution.

The present method is a hot work method which solves the problems of Japanese Patent Application No. 05-101005, and which makes it possible to determine the optimum rolling order and the charging order of the heating furnace that are consistent with the capabilities of the heating furnace and rolling mill. An object is to provide a logistics scheduling method for a rolling mill.

[0008]

[Means for Solving the Problems] In order to determine the charging furnace, heating order, and rolling order of a rolling mill slab composed of a plurality of heating furnaces and rolling mills, the attributes of the material slab to be rolled are input. A slab data input unit having a function, a width sorting unit having a function of sorting by attributes, a rolling constraint matrix calculation unit that calculates rolling constraint conditions by a matrix by attributes, a rolling evaluation value matrix calculation unit that calculates an evaluation function related to rolling,
From the heating furnace constraint calculation unit that calculates the constraint conditions for distributing slabs to each heating furnace, and the heating furnace evaluation value calculation unit that calculates the values of multiple evaluation variables when each slab is charged into an appropriate heating furnace. In the scheduling method using the device, a search using a certain evaluation variable value is performed in the course of the search for the charging furnace of each slab, while keeping the condition that the evaluation variable value not used for the search does not deteriorate more than a certain value. By repeating the search while switching the evaluation variables,
The solution is to determine the optimum charging furnace.

[0009]

Next, the present invention will be described with reference to the drawings. The structure of the hot rolling mill is shown in FIG.

The slab placed in the slab storage area 201 or the slab carried by the freight car 202 is placed on the table 203 in front of the heating furnace, and the heating furnace 204 is composed of three furnaces.
Is charged to. At this time, charging slab (cold pieces depending on temperature,
An appropriate furnace is determined and charged (for hot pieces, etc.). The slab in the heating furnace is heated according to the charging slab temperature, given the in-furnace time (time spent in the heating furnace) and the extraction temperature. The slab that has reached the extraction temperature according to the schedule is extracted from the heating furnace after waiting for the time interval necessary for the previous extraction slab and rolling, and is rolled by VSB (slab width control rolling mill), rough rolling mill 206, and finish rolling mill 207. Then, it is water-cooled by an ROT (cooling table) 208 and wound by a coiler 209. The manufactured coils are used for product storage 2
It is transported to 10.

FIG. 3 shows the hardware configuration for implementing the scheduling method used for physical distribution control of this equipment, and FIG. 1 shows the configuration of the processing (software in this example) of this scheduling method.

In this scheduling device, by the processing shown in the following first to sixth steps,
Approximately 80 to 150 slabs are rolled and the charging furnace is determined.

Step 1: The slab attributes are input by the slab data input unit 101 by file transfer via the keyboard 303, the mouse 305 or the network 304. Table 1 below shows an example of the attribute information.

[0014]

[Table 1]

Step 2: The width sort unit 102 sorts the input slab attribute data in order of increasing width.

Step 3: Next, the rolling order is determined (10
3).

The rolling constraint matrix calculation unit 104 obtains a rolling constraint matrix from the material slab operation rules (rolling constraint) and the slab arrival time sorted in step 2. It is an absolute position constraint matrix A that represents the constraint of the absolute position of the rolling sequence (the range of the rolling sequence is specified for each slab, for example, from 1st to 8th), and the relative position that represents the constraint of the relative position of the front and rear slabs. A relative position constraint matrix R representing constraints (specifying that slab 2 can be rolled but slab 3 cannot be rolled after slab 1) is generated.

[0018]

[Equation 1]

In the rolling evaluation value matrix calculation unit 105, an evaluation value matrix e indicating the difficulty of rolling two slabs which are continuously rolled.
Generate [i] [j]. For example, under the condition of the following expression (5), the evaluation value matrix of the following expression (6) is obtained.

[0020]

[Equation 2]

The rolling time as an evaluation function, that is, the rolling time interval p [i] [j] required when continuously rolling the slabs s [i] and s [j] is calculated based on the actual operation data. Calculate to.

The rolling order solution searching unit first generates a rolling order that can be executed.

For N slabs, the decision variable x is as follows.

[0024]

[Equation 3]

Step 4: Next, the charging heating furnace for the slab whose rolling order has been determined is determined.

In the heating furnace constraint calculation 108, the maximum moving speed of each slab when the maximum fuel is supplied to the heating furnace is obtained by the heat balance equation of the heating furnace. As the efficiency, the result calculated from the actual operation data is used.

[0027]

[Equation 4]

In the charging furnace solution searching unit 109, furnace numbers 1 to N of the heating furnace are first assigned to each slab as initial values. After that, the search for the optimum charging furnace using the values of the plurality of evaluation variables is executed. As an example, a case will be described here where the extraction time, the required fuel, and the cost are three evaluation variables.

First, the extraction time is calculated. The minimum value of the moving speed of the slab in the same furnace is defined as the moving speed of the slab in the heating furnace.
The heating furnace extraction time interval is obtained from the moving speed of the slab in the heating furnace and the slab width, and the rolling time interval p [i] [j], whichever is larger, is taken as the extraction time interval.

That is, the required time interval when rolling the slab j after the slab i is as follows.

[0031]

[Equation 5] Required time interval = max (p [i] [j], w [j] / moving speed of slab in heating furnace) (13) Extracting each slab by integrating the required time interval in the rolling order The time is obtained, and the extraction time of the slab to be extracted last is used as the extraction time.

Next, the required fuel is calculated by the following equation using the extraction time.

[0033]

[Equation 6]

Finally, the cost evaluation value is calculated by the following equation. The coefficients Ct and Cq in this case are set based on the operation result data.

[0035]

[Equation 7] Evaluation value = C _t × extraction time + C _q × required fuel (15) Next, the procedure for searching the charging furnace for each slab using the three evaluation variable values described above will be described. . In this search, a search using one of a plurality of evaluation variables is executed to find the optimum charging furnace, and then the search using another evaluation variable is performed using the optimum charging furnace as an initial solution. . Hereinafter, this search procedure is repeated while switching the evaluation variables until the evaluation variable values do not become small. At this time, a combination in which the evaluation variable value not used for the search deteriorates by a certain ratio or more with respect to the initial evaluation variable value is not updated as the optimum charging furnace.

As an example, the procedure for searching the charging furnace for each slab when processing in the order of extraction time, required fuel, and cost is shown below.

First, evaluation variable values T0, Q0, and C0 of extraction time, required heat quantity, and cost are obtained for the initial charging furnace of each slab. Next, using the extraction time as an evaluation variable, temporarily move several slab furnace numbers to calculate the evaluation variable value,
If the evaluation variable value of the extraction time becomes smaller, the solution is moved. However, the remaining evaluation variables required fuel and cost evaluation variables are a certain percentage (A%) of Q0 and C0.
If it becomes worse, do not change it as a solution. When the evaluation value does not become small by repeating the above operation, the search is stopped. The three evaluation variable values of the solution at this point are T1 (evaluation variable value of extraction time), Q1 (evaluation variable value of required fuel), C1.
(Evaluation variable value of cost).

Next, the required fuel is used as an evaluation variable, the solutions up to the above are used as initial solutions, and the evaluation variable value of the required heat quantity is calculated by temporarily moving several slab furnace numbers and calculating the evaluation variable value. If becomes smaller, the solution is moved.
However, if the evaluation variables of the remaining evaluation variables, extraction time and cost, deteriorate by more than a certain percentage (A%) of T1 and C1, do not change the solution. Repeat the above operation,
Stop the search when the evaluation value does not become small. The three evaluation variable values of the solution at this point are T2 (evaluation variable value of extraction time), Q2 (evaluation variable value of required fuel), and C2 (evaluation variable value of cost).

Next, the cost is used as an evaluation variable, the solutions up to the above are used as initial solutions, and the evaluation variable values are calculated by moving some slab furnace numbers and calculating the evaluation variable values. If so, change the solution to the moved state. However, if the extraction variables, which are the remaining evaluation variables, and the evaluation variable values of the required fuel deteriorate by more than a certain percentage (A%) of T2 and Q2, do not change the solution. When the evaluation value does not become small by repeating the above operation, the search is stopped. The three evaluation variable values of the solution at this point are T3 (evaluation variable value of extraction time), Q3 (evaluation variable value of required fuel), and C3 (evaluation variable value of cost). Repeat the above series of operations with extraction time, required fuel, and cost as evaluation variables for the search,
The search ends when the evaluation variable value does not become small,
The solution at that point is the optimum charging furnace.

FIG. 4 shows an example of the result of searching the charging furnace.
FIG. 4 shows a case where the evaluation variables are switched in the order of extraction time, required fuel, cost, extraction time, required heat quantity, and cost from the initial schedule (actual operation schedule),
The intermediate results of each evaluation variable value are shown. The limit value (A%) to the evaluation variable value not used in the search was set to 20%.

As can be seen from these results, all three evaluation variable values were significantly improved with respect to the initial schedule. In particular, although there is a trade-off relationship between the extraction time and the required fuel, the three evaluation variables converge to the optimum value almost smoothly due to the effect of the limit value (A%).

Step 5: Physical distribution simulation section 11
At 0, the required fuel, slab temperature, and slab retention status are calculated in detail using a simulator that has a detailed model for the slab with a fixed rolling order, heating furnace number, and extraction time, and a more accurate evaluation value is calculated. To do.

Step 6: The result output unit 111 outputs the rolling order, the charging order, and the simulation result as a result.

The present invention can also be applied to heating and rolling processes for billets such as steel bars and wire rods.

[0045]

EFFECTS OF THE INVENTION By optimizing a plurality of evaluation variable values separately, it becomes possible to determine the optimum charging furnace for each slab that minimizes all evaluation variable values, so that an optimum distribution can be carried out. . As a result, productivity can be improved, costs can be reduced, and quality can be stabilized.

[Brief description of drawings]

FIG. 1 is a flowchart showing a processing configuration of a distribution scheduling device in a hot rolling plant.

FIG. 2 is a block diagram showing an actual hot rolling mill.

FIG. 3 is a block diagram showing an embodiment of hardware for realizing the configuration of FIG. 1 and the operation of FIG.

FIG. 4 is a map showing an example of a schedule result.

[Explanation of symbols]

101: Slab data input section 102:
Width sort part 103: Rolling order determination 104:
Rolling constraint matrix calculation unit 105: Rolling evaluation value matrix calculation unit 106:
Rolling sequence solution search unit 107: Charge furnace determination 108:
Heating furnace constraint calculation unit 109: Charge furnace solution search unit 110:
Physical distribution simulation unit 111: Result output unit 201:
Slab storage 202: Freight car 203:
Table before heating furnace 204: Heating furnace 205:
VSB 206: Rough rolling mill 207:
Finishing rolling mill 208: ROT 209:
Coiler 210: Shows product storage d:
Rolled slab e: Coil f: Slab, showing the moving direction of the coil 301: Display, 302:
Workstation 303: Keyboard 304:
Mouse 305: Hard disk 306:
network

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Claims (1)

[Claims] 1. A rolling mill having a plurality of heating furnaces and rolling mills has a function of inputting attributes of a material slab to be rolled in order to determine a slab charging furnace, a heating order, and a rolling order. Slab data input unit, width sorting unit having a function of sorting by attributes, rolling constraint matrix calculation unit that calculates rolling constraint conditions by a matrix by attributes, rolling evaluation value matrix calculation unit that calculates an evaluation function for rolling, and determines the rolling order A rolling order solution search section with functions, a heating furnace constraint calculation section that calculates the constraint conditions for distributing slabs with a fixed rolling order to each heating furnace, and an evaluation function by loading each slab into an appropriate heating furnace. The method of calculating the charging furnace of each slab, searching for the optimum solution and determining the charging furnace by determining the charging furnace solution In the process of searching the charging furnace for each slab, a search using a certain evaluation variable value is performed under the condition that the evaluation variable value not used for the search does not deteriorate beyond a certain numerical value. A logistics scheduling method for a rolling mill, characterized by determining an optimum charging furnace by repeating a search while switching evaluation variables.