JP2011206801A - Rolling method of steel plate and pass schedule calculation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To roll a steel plate into a target shape with high accuracy.SOLUTION: A pass schedule calculation device virtually divides a steel plate of each pass in a longitudinal direction in such a way that cross sections of divided parts become the same between passes, and estimates a forward slip at each dividing point based on the positional change between the passes of each dividing point. Accordingly, the position Pof the dividing point of the steel plate 2 at i-th pass becomes the position P' at the next i+1th pass from the principle of conservation of mass flow, and coincides with the position Pof the dividing point of the steel plate 2 at the i+1th pass, so that an error is not caused at an outlet side plate thickness used in calculating the forward slip. A position in the longitudinal direction of the steel plate 2 is calculated with high accuracy and the steel plate is rolled into a target shape with high accuracy.

Description

  The present invention relates to a steel sheet rolling method for rolling a steel sheet by repeating a rolling process by a rolling mill a plurality of passes, and a pass schedule calculation method for preliminarily calculating a rolling mill reduction position in each pass as a pass schedule.

  In recent years, from the viewpoint of weight reduction of structures, reduction of material costs, omission of welding process, etc., deformed steel sheets in which the steel sheet thickness is changed at a constant rate in the longitudinal direction at the rolling stage have come to be used. It is coming. Such a deformed steel sheet is manufactured by repeating a rolling process by a reversible rolling mill a plurality of times. Hereinafter, in this specification, one rolling process by a reversible rolling mill is expressed as one pass. That is, the deformed steel sheet is manufactured by repeating the rolling process a plurality of passes.

  In order to manufacture the plate thickness of the deformed steel plate with high accuracy, it is important to control the longitudinal position of the steel plate in each pass with high accuracy. And in order to control the longitudinal direction position of the steel plate in each pass with high accuracy, the longitudinal direction position of the steel plate in each pass is measured with high accuracy and between the rolling rolls with respect to the longitudinal direction position of the steel plate in each pass. It is important to set the gap (reduction position) of the above with high accuracy.

  Effective methods for measuring the longitudinal position of the former with high accuracy include increasing the prediction rate of the steel sheet advanced rate prediction formula and correcting the longitudinal position by measuring the tip position of the steel sheet with a sensor. It is. For example, Patent Document 1 discloses that a longitudinal position of a steel plate during rolling is increased by correcting an advanced rate prediction formula using a plurality of tip detection devices and plate speed detection devices installed on the downstream side of the rolling mill. A method of accurately measuring is disclosed.

  On the other hand, as a method of setting the latter reduction position with high accuracy, a rolling load with respect to the longitudinal direction position of the steel sheet is predicted, a calculation method of the reduction position based on the predicted rolling load, A method of correcting the reduction position so as to reduce the influence on the sheet thickness due to the difference in rolling load when different from the rolling load is effective. A method of increasing the number of division points for predicting the rolling load and reducing errors due to linear interpolation is also conceivable. For example, Patent Document 2 discloses a method of approximation using three adjacent dividing points, paying attention to the fact that the mill stiffness, which is an influence coefficient for the rolling load and the reduction position, differs depending on the rolling load region and is not proportional.

  In the method described in Patent Document 2, n division points are generated by dividing the plate thickness change amount of the steel plate into n equal parts. Dividing the plate thickness change amount into n is equivalent to dividing the plate thickness change amount into n in the longitudinal direction in a deformed steel sheet in which the plate thickness change amount changes at a constant rate with respect to the longitudinal direction. Therefore, when the method described in Patent Document 2 is applied to the manufacturing process of a deformed steel sheet, n division points are generated by dividing the total length of the steel sheet into n parts, and a rolling load and a reduction position are predicted for each division point. Then, the reduction position is corrected based on the prediction result.

JP-A-8-309415 JP 2008-246511 A

  By the way, when correcting the rolling position during rolling, the rolling position is changed according to the longitudinal position l of the steel sheet. The longitudinal position l of the steel sheet is expressed by the following mathematical formulas (1) and (2). Calculated. In equation (1), parameter f represents the advance rate, parameter N represents the work roll rotation speed [1 / s] for each sampling period, parameter R represents the work roll diameter [mm], and parameter Δt represents the sampling period [s]. Further, in Equation (2), the parameter r represents the rolling reduction, the parameter H represents the entry side plate thickness [mm] of the steel plate, and the parameter h represents the exit side plate thickness [mm] of the steel plate.

  That is, the longitudinal position 1 of the steel plate is expressed by an expression obtained by multiplying the work roll rotational speed N by (1 + advance rate f). Here, in the manufacturing process of the deformed steel sheet, since the entry side plate thickness H and the exit side plate thickness h of the steel sheet change sequentially, the advanced rate f also changes sequentially, as is apparent from Equation (2). Therefore, when calculating the longitudinal position 1 of the steel sheet, it is necessary to sequentially change the advanced rate f based on the mathematical formula (2).

However, when dividing points are generated by dividing the entire length of the steel plate into n equal parts in each pass, the position of the dividing point before rolling and the position of the dividing point after rolling do not exactly match from the principle of constant mass flow. Specifically, the position P _A of the dividing points of the steel plate 2 in the i-th path shown in FIG. 9 (a), as shown in FIG. 9 (b), the position P _{A 'becomes} the next (i + 1) -th pass , The position P _B of the dividing point of the steel plate 2 in the (i + 1) th pass does not match. As shown in FIG. 9C, the amount of deviation increases as the number of passes increases.

Therefore, when dividing points are generated by dividing the total length of the steel sheet into n equal parts in each pass, an error occurs in the outgoing side sheet thickness h used when calculating the advance rate f. Specifically, in the example shown in FIG. 9B, the plate thickness h1 at the position P _A ′ must be used as the outlet side plate thickness h when calculating the advance rate, but the plate thickness h2 at the position P _B is used. Is used as the outlet side plate thickness h, an error occurs in the calculated advance rate f. For this reason, when the dividing point is generated by dividing the total length of the steel plate into n equal parts in each pass, an error is included in the longitudinal plate thickness accuracy because the calculated longitudinal position l includes an error. The deformed steel sheet cannot be rolled into the target shape.

  This invention is made | formed in view of the said subject, The objective is to provide the rolling method and pass schedule calculation method of the steel plate which can roll a steel plate accurately to the target shape.

  In order to solve the above-described problems and achieve the object, a rolling method of a steel sheet according to the present invention is a rolling method of a steel sheet that rolls a steel sheet by repeating a rolling process by a rolling mill a plurality of passes, wherein Based on the division step of virtually dividing the steel plate of each pass in the longitudinal direction so that the area is the same between the passes, and the position change between the passes of each division point generated by the division step, at each division point Control that predicts the advance rate and calculates the longitudinal position of the steel sheet using the advance rate at each dividing point predicted by the predict step, and controls the reduction position of the steel sheet based on the calculated longitudinal position Steps.

  In order to solve the above-mentioned problems and achieve the object, a pass schedule calculation method according to the present invention is a rolling mill in each pass in a rolling method of a steel plate in which a steel plate is rolled by repeating a rolling process by a rolling mill a plurality of passes. And a dividing step for virtually dividing the steel plate of each pass in the longitudinal direction so that the cross-sectional area of the dividing portion is the same between the passes. The path schedule is calculated using the prediction step for predicting the advance rate at each division point and the advance rate at each division point predicted by the prediction step based on the position change between the paths at each division point generated by A calculation step.

  According to the steel sheet rolling method and the pass schedule calculation method according to the present invention, the position of the dividing point does not change before and after rolling, and the advanced rate can be calculated with high accuracy, so that the target shape can be accurately obtained. A steel plate can be rolled.

FIG. 1 is a schematic diagram showing a configuration of a reversible rolling mill according to an embodiment of the present invention. FIG. 2 is a flowchart showing the flow of a path schedule calculation process according to an embodiment of the present invention. FIG. 3 is a schematic diagram for explaining the thickness and length of the exit side plate of the thickest part and the thinnest part of the steel plate. FIG. 4 is a schematic diagram showing a state in which the steel sheet is divided equally in the longitudinal direction. FIG. 5 is a schematic diagram showing the plate thickness and plate length at each division point of the steel plate. FIG. 6 is a schematic diagram for explaining a method of calculating the plate thickness and the plate length at each division point of the steel plate. FIG. 7 is a graph showing the relationship between the longitudinal position of the steel plate and the plate thickness. FIG. 8 is a diagram for explaining the concept of a path schedule calculation process according to an embodiment of the present invention. FIG. 9 is a diagram for explaining the concept of a conventional path schedule calculation process.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[Configuration of reversible rolling mill]
First, the configuration of a reversible rolling mill according to an embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a schematic diagram showing a configuration of a reversible rolling mill according to an embodiment of the present invention. As shown in FIG. 1, a reversible rolling mill 1 according to an embodiment of the present invention includes a pair of upper and lower work rolls 3a and 3b for rolling a steel plate 2, and a pair of upper and lower work rolls for backing up a pair of upper and lower work rolls 3a and 3b. Backup rolls 4a and 4b. The reversible rolling mill 1 rolls a steel sheet into a desired shape by repeating a rolling process (hereinafter referred to as a pass) for conveying the steel sheet 2 between a pair of upper and lower work rolls 3a and 3b.

  The reversible rolling mill 1 includes a pass schedule calculation device 11, a load cell 12, a pulse generator 13, a plate thickness control device 14, a controller 15, a servo valve 16, and a hydraulic cylinder 17 as a control system. The pass schedule calculation device 11 is configured by a calculation device such as a computer. The pass schedule calculation device 11 calculates the plate thickness change amount, the advance rate, the predicted load, the initial reduction position, and the control mill rigidity value in each pass, and inputs the calculation results to the plate thickness control device 14.

  The load cell 12 detects the rolling load of the pair of upper and lower work rolls 3 a and 3 b and inputs a signal indicating the detected rolling load to the plate thickness control device 14. The pulse generator 13 detects the rotation speed of the work roll 3 a and inputs a signal indicating the detected rotation speed to the plate thickness control device 14. The plate thickness control device 14 performs AGC control of the opening degree of the servo valve 16 via the controller 15 based on input information from the pass schedule calculation device 11, the load cell 12, and the pulse generator 13. The hydraulic cylinder 16 moves up and down according to the opening degree of the servo valve 16 and adjusts a gap (a reduction position) between the work roll 3a and the work roll 3b.

[Pass schedule calculation processing]
In the reversible rolling mill 1 having such a configuration, the pass schedule calculation device 11 increases the advanced rate used when calculating the longitudinal position of the steel plate 2 by executing the following pass schedule calculation process. Calculated with high accuracy, enabling the steel sheet to be rolled with high accuracy into the desired shape. Hereinafter, with reference to the flowchart shown in FIG. 2, the operation of the path schedule calculation device 11 when this path schedule calculation process is executed will be described.

  The flowchart shown in FIG. 2 starts when the execution instruction of the path schedule calculation process is input to the path schedule calculation device 11, and the path schedule calculation process proceeds to the process of step S1.

In the process of step S1, the pass schedule calculation device 11 calculates the exit side plate thickness h ₀ (i) and the plate length L _n (i) of the thinnest portion of the steel plate 2 shown in FIG. 3 in each pass. The subscript parameter i is a parameter indicating the order of the passes, and the subscript parameter n is a parameter indicating the number of divisions in the longitudinal direction of the steel plate 2. Thereby, the process of step S1 is completed and the path schedule calculation process proceeds to the process of step S2.

  In the process of step S <b> 2, the pass schedule calculation device 11 determines the order tp of the passes (taper start pass) for starting the rolling process for changing the plate thickness of the steel plate 2 in the longitudinal direction. Thereby, the process of step S2 is completed, and the path schedule calculation process proceeds to the process of step S3.

In the process of step S3, the pass schedule calculation device 11 calculates the outlet side plate thickness h _n (i) of the thickest portion of the steel plate 2 shown in FIG. 3 in each pass. Thereby, the process of step S3 is completed, and the path schedule calculation process proceeds to the process of step S4.

In the process of step S4, as shown in FIG. 4, the pass schedule calculation device 11 equally divides the steel plate 2 in the tp-th path determined by the process of step S3, that is, the taper start path, into n in the longitudinal direction. , N division parts having a cross-sectional area S _k (k = 1 to n) are generated. In the present embodiment, although equally n divide the steel plate 2 in the longitudinal direction, for example, _{a 1: a 2: a 3} : ...: and n dividing the steel plate 2 in the longitudinal direction at a predetermined ratio, such as a _n Also good. Thereby, the process of step S4 is completed, and the path schedule calculation process proceeds to the process of step S5.

  In the process of step S5, the pass schedule calculation device 11 sets the value of the program counter i for counting the pass order to tp + 1. Thereby, the process of step S5 is completed, and the path schedule calculation process proceeds to the process of step S6.

In the process of step S6, as shown in FIG. 5, the path schedule calculation device 11 has the same sectional area S _k (k = 1 to n) of the n divided parts generated by the process of step S4 between the paths. Thus, the steel plate 2 in the i-th path corresponding to the value of the program counter i is divided into n in the longitudinal direction. Incidentally, _a 1 in the processing of step _{S4: a 2: a 3:} ...: when n dividing the steel plate 2 in a predetermined ratio, such as _{a n} in the longitudinal direction, pass schedule calculation unit 11, the ratio is path The steel plate 2 is divided into n in the longitudinal direction so as to be equal to each other. That is, the pass schedule calculation device 11 divides the steel plate 2 in the i-th pass corresponding to the value of the program counter i into n parts in the longitudinal direction so that the cross-sectional areas of the n division parts are equal between passes. Thereby, the process of step S6 is completed, and the path schedule calculation process proceeds to the process of step 7.

In the process of step S7, the pass schedule calculation device 11 calculates the plate length L _n (i) of the steel plate 2 in the i-th pass corresponding to the value of the program counter i. Specifically, when i = tp + 1, the mass flow is constant, the sectional area of the entire length of the steel plate 2 in the i-th pass is S, and the gradient g of the thickness of the steel plate 2 in the i-th pass is the total length of the steel plate 2 And the plate length L _n (i) of the steel plate 2 in the i-th pass can be calculated by the following Equation 3. Thereby, the process of step S7 is completed, and the path schedule calculation process proceeds to the process of step S8.

In the process of step S8, the pass schedule calculation device 11 calculates the plate thickness h _k (i) and the plate length L _k (i) at each division point divided by the process of step S6. Specifically, when the taper amount α _k and the length ΔL _k in the longitudinal direction of the k-th divided portion are defined as shown in FIG. 6, the gradient g and the cross-sectional area S _{k of the} divided portion are respectively expressed by the following equations 4 , 5.

Further, the sectional area S _k of the divided portion is expressed by the following Expression 6 from Expressions 4 and 5, and the following Expression 7 is obtained by arranging Expression 6 by the taper amount α _k . Accordingly, the taper amount α _k is expressed by the following Expression 8 by solving Expression 7, and h _k (i) and the plate length L _k (i) at each division point are expressed by Expressions 9 and 10 below. expressed. Therefore, the pass schedule calculation device 11 calculates the plate thickness h _k (i) and the plate length L _k (i) at each division point using the following mathematical formulas 9 and 10. According to the processing of step S7 and step S8, for example, for the tp + 1th pass, as shown in FIG. 5, the plate thickness h _k (tp + 1) and the plate length L _k (tp + 1) at each division point are calculated. . Thereby, the process of step S8 is completed, and the path schedule calculation process proceeds to the process of step S9.

In the process of step S9, the pass schedule calculation device 11 determines whether or not the plate thickness h _k (i) and the plate length L _k (i) at each division point have been calculated for all passes. As a result of the determination, if the plate thickness h _k (i) and the plate length L _k (i) at each division point are not calculated for all the passes, the pass schedule calculation device 11 performs the program counter i as the process of step S10. Then, the pass schedule calculation process is returned to the process of step S6. On the other hand, when the plate thickness h _k (i) and the plate length L _k (i) at each division point are calculated for all the passes, the pass schedule calculation device 11 changes the pass schedule calculation processing to the processing of step S11. move on.

In the process of step S11, the pass schedule calculation device 11 calculates the advance rate f _k (i), the load P _k (i), and the plate thickness change amount Δh _k (i) at each dividing point for each pass. The result is input to the plate thickness controller 14. The calculation method of these values is already known at the time of filing of the present invention and will not be described in detail. However, the advanced rate f _k (i) at each dividing point is the thickness h of each dividing point. It can be calculated by substituting _k (i) as the exit side plate thickness h in the above-described equation 2. Further, P _k (i) at each division point can be calculated using a rolling load equation such as a Bland & Ford equation or a Hill equation. Further, the plate thickness change amount Δh _k (i) can be calculated by obtaining a plate thickness difference from an adjacent division point. Thereby, the process of step S11 is completed and a series of path schedule calculation processes are complete | finished.

  Thereafter, the plate thickness control device 14 calculates the advance rate between division points, the predicted load, and the plate thickness change amount for each pass by linear interpolation, and the longitudinal position Lfb and the plate thickness of the steel plate 2 as shown in FIG. Find the relationship with h. And the plate | board thickness control apparatus 14 calculates the longitudinal direction position l of the steel plate 2 using Numerical formula 1 already stated, Based on the calculation result, a reduction position so that a plate | board thickness deviation may become zero according to the relationship shown in FIG. AGC is performed to roll the steel plate 2 into a target shape.

As is clear from the above description, in the pass schedule calculation process according to an embodiment of the present invention, the pass schedule calculation device 11 extends the length of the steel plate of each pass so that the cross-sectional area of the divided portion is the same between the passes. Virtually dividing in the direction, the advance rate at each dividing point is predicted based on the positional change between the paths of each dividing point. According to such a pass schedule calculation process, as shown in FIG. 8 (a) ~ (c) , the position P _A of the dividing points of the steel plate 2 in the i-th path from the mass flow constant principles, the following In the i + 1-th pass, the position is P _A ′, which coincides with the position P _B of the dividing point of the steel plate 2 in the i + 1-th pass, so that no error occurs in the exit side plate thickness used when calculating the advance rate. Therefore, according to such a pass schedule calculation process, the longitudinal position of the steel plate 2 can be calculated with high accuracy, and the deformed steel plate can be rolled into a target shape with high accuracy.

  Although the embodiment to which the invention made by the present inventor is applied has been described above, the present invention is not limited by the description and the drawings that form a part of the disclosure of the present invention according to this embodiment. For example, in the present embodiment, the present invention is applied to a manufacturing process of a deformed steel sheet whose thickness changes at a constant rate in the longitudinal direction, but the present invention is not limited to this embodiment, and the width Any process that changes the shape of the steel sheet in the longitudinal direction, such as a manufacturing process of a steel sheet whose dimensions change at a constant rate in the longitudinal direction, a process of making the thickness of the deformed steel sheet uniform in the longitudinal direction, and the like can be applied. As described above, other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the present embodiment are all included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Reversible rolling mill 2 Steel plate 3a, 3b Work roll 4a, 4b Backup roll 11 Pass schedule calculation device 12 Load cell 13 Pulse generator 14 Plate thickness control device 15 Controller 16 Servo valve 17 Hydraulic cylinder

Claims (3)

A rolling method for a steel sheet, in which a steel sheet is rolled by repeating a rolling process by a rolling mill a plurality of passes,
A dividing step of virtually dividing the steel plate of each pass in the longitudinal direction so that the cross-sectional area of the dividing portion is the same between passes;
A predicting step of predicting an advance rate at each dividing point based on a positional change between paths of each dividing point generated by the dividing step;
Calculating the longitudinal position of the steel sheet using the advance rate at each dividing point predicted by the prediction step, and controlling the rolling position of the steel sheet based on the calculated longitudinal position;
A rolling method of a steel sheet, comprising:   The steel plate is a deformed steel plate in which the plate thickness of the steel plate changes at a constant rate in the longitudinal direction, and the prediction step calculates the plate thickness of the steel plate at the k-th division point in the i-th pass on the entry side of the rolling mill. The present invention includes a step of predicting an advance rate at each division point, with the plate thickness, the plate thickness of the steel plate at the k-th division point in the (i + 1) th pass as the plate thickness on the outlet side of the rolling mill. The rolling method of the steel plate as described. In the rolling method of a steel sheet that rolls a steel sheet by repeating a plurality of passes through a rolling process by a rolling mill, a pass schedule calculation method that calculates the rolling position of the rolling mill in each pass as a pass schedule,
A dividing step of virtually dividing the steel plate of each pass in the longitudinal direction so that the cross-sectional area of the dividing portion is the same between passes;
A predicting step of predicting an advance rate at each dividing point based on a positional change between paths of each dividing point generated by the dividing step;
A calculation step of calculating the path schedule using an advanced rate at each division point predicted by the prediction step;
Including a path schedule calculation method.

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