JP2022014800A - Rolling control method for metal strip, rolling control device, and production method - Google Patents

Abstract

To provide a rolling control method for a metal strip that can prevent the occurrence of a contraction, a rolling control device, and a production method.SOLUTION: A rolling control method for a metal strip includes a calculation step for calculating a twist in a metal strip at the input side of a rolling machine, a C warp, and an edge wave, and a rolling control step in which, if at least one of the twist, C warp, and edge wave in the metal strip calculated in the calculation step is equal to or higher than a predetermined threshold, a rolling reduction at the center of the metal strip in the width direction is set to be relatively larger relative to a rolling reduction at an edge of the metal strip in the width direction.SELECTED DRAWING: Figure 2

Description

The present invention relates to a rolling control method, a rolling control device, and a manufacturing method for metal strips.

In a general metal strip rolling process, in order to produce a flat metal strip, the flatness of the metal strip during rolling is measured in real time, and a shape control actuator is used so that the measured flatness matches the target value. Is being manipulated. However, when the flatness of the metal strip before rolling is extremely poor, even if the shape of the metal strip after rolling is controlled to be flat, linear scratches called drawing may occur in the metal strip. When the drawn portion of the metal strip is rolled, the rolling roll may be scratched, a loss time may occur due to the replacement of the rolling roll, and the production efficiency may decrease.

Generally, the flatness of a metal band is represented by steepness, elongation difference rate, and I-Unit. Specifically, the steepness λ'is expressed by the ratio of the wave height δ of the metal band S shown in FIG. 5 to the wave pitch L as shown in the following mathematical formula (1). Further, the elongation difference rate Δε is represented by the ratio of the elongation difference ΔL of the metal band S shown in FIG. 5 to the pitch L of the wave as shown in the following mathematical formula (2). Further, when the shape of the metal band S is approximated by a sine and cosine curve, the steepness λ'and the elongation difference rate Δε are in the relationship shown in the following mathematical formula (3). Further, I-Unit is a value obtained by multiplying the elongation difference rate Δε by 10 to the 5th power as shown in the following mathematical formula (4).

As a method for measuring the flatness of the metal strip during rolling, for example, a flatness meter having a disk structure in which the rolling roll is divided in the width direction and a load detection sensor is embedded in each of the rolling rolls is used between the metal strip and the rolling roll. There is a method to calculate the shape of the metal band by measuring the contact load of. In addition, as the shape control actuator, in order to control the shape of the metal strip by changing the axial deflection of the work roll, a roll bender mechanism that applies bender force to both ends of the work roll and an intermediate roll with one taper are used in the width direction. There is an intermediate roll shift mechanism that shifts to. There is also a VC (Variable Crown) roll mechanism that operates the roll crown by hydraulic pressure.

On the other hand, Patent Document 1 predicts changes in the shape (flatness) of the metal strip in the hot rolling step, the cooling step, and the winding step, especially in the temper rolling step after hot rolling, and temper rolling. A rolling control method has been proposed in which a set value is determined so as to optimize the shape of the metal strip after the process.

Japanese Unexamined Patent Publication No. 2016-49553

However, the rolling control method described in Patent Document 1 performs rolling control only from the viewpoint of controlling the flatness of the metal band, and does not perform rolling control from the viewpoint of preventing rolling (narrowing) of the drawn portion.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a rolling control method, a rolling control device, and a manufacturing method for a metal strip capable of suppressing the occurrence of drawing.

The rolling control method for a metal strip according to the present invention includes a calculation step for calculating the twist, C warp, and ear elongation of the metal strip on the entry side of the rolling mill, and the twist and C warp of the metal strip calculated in the calculation step. , And a rolling control step that increases the amount of rolling in the center of the width direction relative to the amount of rolling in the widthwise end of the metal strip when at least one of the ear elongations is greater than or equal to a predetermined threshold. And.

The rolling control device for a metal strip according to the present invention has a measuring means for measuring the height distribution in the width direction of the metal strip on the entrance side of the rolling mill and a height distribution in the width direction of the metal strip measured by the measuring means. The twist, C warp, and ear elongation of the metal band on the entrance side of the rolling mill are calculated from, and if at least one of the calculated twist, C warp, and ear elongation of the metal band is equal to or greater than a predetermined threshold value, the metal band It is characterized by comprising a control means for relatively increasing the rolling amount in the center portion in the width direction with respect to the rolling amount in the end portion in the width direction.

The method for manufacturing a metal strip according to the present invention is characterized by including a step of manufacturing the metal strip by utilizing the method for controlling rolling of the metal strip according to the present invention.

According to the rolling control method, the rolling control device, and the manufacturing method of the metal strip according to the present invention, the occurrence of drawing can be suppressed.

FIG. 1 is a schematic diagram showing a configuration example of a rolling mill to which the rolling control method for metal strips according to the embodiment of the present invention is applied. FIG. 2 is a flowchart showing the flow of the rolling control process according to the embodiment of the present invention. FIG. 3 is a diagram for explaining the twist and C warp of the metal band. FIG. 4 is a diagram for explaining the twist and C warp of the metal band. FIG. 5 is a diagram for explaining the steepness and elongation difference ratio of the metal band.

Hereinafter, a method for controlling rolling of a metal strip, which is an embodiment of the present invention, will be described with reference to the drawings.

[Structure of rolling mill]
First, with reference to FIG. 1, the configuration of a rolling mill to which the rolling control method for metal strips according to the embodiment of the present invention is applied will be described.

FIG. 1 is a schematic diagram showing a configuration example of a rolling mill to which the rolling control method according to the embodiment of the present invention is applied. As shown in FIG. 1, in the rolling mill 1 to which the rolling control method for the metal strip according to the embodiment of the present invention is applied, the metal strip S is dispensed and wound up by using the reel 2a and the reel 2b. It is a four-stage rolling mill that corrects the shape of the metal strip S by rolling the strip S, and is a pair of work rolls 3a, 3b, a pair of backup rolls 4a, 4b, a laser scanner 5, a flatness meter 6, and a control. The device 7 is provided.

The pair of work rolls 3a and 3b are arranged so as to face each other in the plate thickness direction of the metal strip S with a transport path for transporting the metal strip S in the arrow direction. The work rolls 3a and 3b continuously roll the metal strip S by rotating (rotating) while sandwiching the metal strip S sequentially transported along the transport path in the plate thickness direction.

The pair of backup rolls 4a and 4b are arranged so as to face each other with the pair of work rolls 3a and 3b interposed therebetween. The upper backup roll 4a comes into contact with the outer peripheral surface of the upper work roll 3a from above and presses the upper work roll 3a downward. As a result, the upper backup roll 4a applies the load required for rolling the metal strip S to the upper work roll 3a. Further, the lower backup roll 4b comes into contact with the outer peripheral surface of the lower work roll 3b from below, and presses the lower work roll 3b upward. As a result, the lower backup roll 4b applies the load required for rolling the metal strip S to the lower work roll 3b.

Although not shown, a roll bender mechanism is connected to the pair of backup rolls 4a and 4b as a shape control actuator. The roll bender mechanism functions as a shape control unit that controls the shape of the metal strip S after rolling by the rolling mill 1. Specifically, the roll bender mechanism imparts bending or inclination to the pair of work rolls 3a, 3b via the pair of backup rolls 4a, 4b to obtain the shape of the metal strip S after rolling by the rolling mill 1. Control. The operation of the roll bender mechanism is controlled by the control device 7.

The laser scanner 5 is composed of a two-dimensional or three-dimensional laser scanner and is installed on the entrance side of the rolling mill 1. The laser scanner 5 measures the height distribution in the width direction of the metal band S on the entry side of the rolling mill 1, and inputs an electric signal indicating the measured height distribution in the width direction to the control device 7. It is desirable that the measurement position of the height distribution of the metal strip S is as close as possible to the work rolls 3a and 3b on the entry side of the rolling mill 1 so that the sign of the occurrence of drawing can be detected at an early stage. Further, in order to suppress the occurrence of a detection error due to the accumulation of dust on the detection unit of the laser scanner 5, it is desirable to install the laser scanner 5 so that the detection unit faces downward as much as possible. An image pickup device may be installed instead of the laser scanner 5, and the height distribution of the metal to S may be measured by image analysis.

The flatness meter 6 is composed of a roll-type flatness meter and is installed on the outlet side of the rolling mill 1. The flatness meter 6 measures the shape of the metal strip S on the exit side of the rolling mill 1, and inputs an electric signal indicating the measured shape to the control device 7.

The control device 7 is composed of an information processing device such as a computer, and controls the operation of the entire rolling mill 1 by using electric signals input from the laser scanner 5 and the flatness meter 6. Further, in the present embodiment, the control device 7 suppresses the occurrence of drawing by executing the rolling control process shown below.

[Rolling control process]
Next, with reference to FIG. 2, the operation of the control device 7 when executing the rolling control process will be described.

FIG. 2 is a flowchart showing the flow of the rolling control process according to the embodiment of the present invention. FIG. 2 starts at the timing when the execution command of the rolling control process is input to the control device 7, and the rolling control process proceeds to the process of step S1. This rolling control process is repeatedly executed at predetermined control cycles until the rolling process of the metal strip S is completed or stopped.

In the process of step S1, the control device 7 calculates the twist of the metal band S based on the height distribution in the width direction of the metal band S on the entrance side of the rolling mill 1 measured by the laser scanner 5. Specifically, as shown in FIG. 3, the control device 7 calculates the inclination θ of the straight line L1 connecting both ends in the width direction of the metal band S with respect to the horizontal direction (straight line L2) as a twist. However, the twist may be an index expressing the inclination of the metal band S with respect to the horizontal direction. For example, as shown in FIG. 4, the twist is the first-order when the height distribution L3 of the metal band S is approximated by a quadratic curve. The coefficient b of the term may be defined as a twist, or the sum e + g of the coefficient e of the cubic term and the coefficient g of the linear term when the height distribution L3 of the metal band S is approximated by a quadratic curve. It may be defined as a twist. As a result, the process of step S1 is completed, and the rolling control process proceeds to the process of step S2.

In the process of step S2, the control device 7 calculates the C warp of the metal strip S based on the height distribution in the width direction of the metal strip S on the entrance side of the rolling mill 1 measured by the laser scanner 5. Specifically, as shown in FIG. 3, the control device 7 calculates the distance H between the straight line L1 connecting both ends in the width direction of the metal band S and the central portion in the width direction of the metal band S as the C warp. do. However, the C warp may be an index expressing the difference between the height of the end portion in the width direction and the height of the center portion in the width direction of the metal band S. For example, as shown in FIG. 4, the height distribution of the metal band S may be used. The coefficient a of the quadratic term when L3 is approximated by a quadratic curve may be defined as C warp, or the height distribution L3 of the metal band S may be defined as the quaternary term when approximated by a quadratic curve. The sum d + f of the coefficient d and the coefficient f of the quadratic term may be defined as C warp. As a result, the process of step S2 is completed, and the rolling control process proceeds to the process of step S3.

In the process of step S3, the control device 7 calculates the ear elongation of the metal band S based on the height distribution in the width direction of the metal band S on the entrance side of the rolling mill 1 measured by the laser scanner 5. Here, the ear elongation may be an index expressing a state in which the elongation at the end portion in the width direction is larger than the elongation at the central portion in the width direction of the metal band S, and the type is not particularly limited. For example, indexes such as steepness λ', elongation difference rate Δε, I-Unit, and wave height δ can be used. As a result, the process of step S3 is completed, and the rolling control process proceeds to the process of step S4.

In the process of step S4, the control device 7 twists the metal band S calculated in the process of step S1, the C warp of the metal band S calculated in the process of step S2, and the metal calculated in the process of step S3. It is determined whether or not at least one of the ear extensions of the band S is equal to or higher than the threshold value. As a result of the determination, when at least one is equal to or greater than the threshold value (step S4: Yes), the control device 7 advances the rolling control process to the process of step S5. On the other hand, if none of them is equal to or greater than the threshold value (step S4: No), the control device 7 ends a series of rolling control processes. The threshold value is a value that changes according to the rolling conditions of the rolling mill 1, and is determined in advance based on the rolling results.

In the process of step S5, the control device 7 controls the shape control actuator to relatively increase the reduction amount of the width direction central portion with respect to the reduction amount of the width direction end portion. Here, the shape control actuator may be any device that can reduce the central portion of the metal band S in the width direction, and examples thereof include a roll bender mechanism, an intermediate roll shift mechanism, an As—U mechanism, and a VC roll. When the metal strip S having a large ear elongation is rolled, the elongation of the widthwise end portion of the metal strip S becomes larger than the elongation of the widthwise central portion, and out-of-plane deformation occurs at the widthwise end portion. Immediately below the roll, this out-of-plane deformation is forcibly flattened, and compressive stress is applied to the widthwise end where the elongation is large, and tensile stress is applied to the widthwise center where the elongation is small so that the elongation at the widthwise end becomes uniform. Occur. As a result, shear buckling occurs due to the stress difference between the widthwise end and the widthwise center. Therefore, in the rolling control process of the present embodiment, the shape control actuator is controlled so that the rolling control amount at the center portion in the width direction is relatively large with respect to the rolling reduction amount at the end portion in the width direction. As a result, the elongation of the end portion in the width direction on the exit side of the rolling mill becomes small, and the state in which the elongation of the end portion in the width direction on the entry side of the rolling mill is large is alleviated, so that the occurrence of drawing can be suppressed. As a result, the process of step S5 is completed, and a series of rolling control processes is completed.

As is clear from the above description, in the rolling control process according to the embodiment of the present invention, the control device 7 calculates the twist, C warp, and ear elongation of the metal strip S on the entry side of the rolling mill 1. When at least one of the calculated twist, C warp, and ear extension of the metal band S is equal to or more than a predetermined threshold value, the rolling amount of the rolling center portion in the width direction is relative to the rolling amount of the rolling end portion of the metal band S. Since it is made large, it is possible to suppress the occurrence of rolling.

[Example 1]
A mild steel plate having an inlet side plate thickness of 1.400 mm, an outlet side plate thickness of 1.386 mm, and a plate width of 1100 mm was rolled. The set values of the unit tension were 20 MPa on the entry side and 40 MPa on the exit side. As the rolling mill, the rolling mill shown in FIG. 1 was used. The work roll diameter of the rolling mill is Φ450 mm, and the backup roll diameter is Φ1200 mm. The rolling mill is equipped with a work roll bender as a shape control actuator. A roll-type flatness meter is installed on the exit side of the rolling mill to measure the shape of the mild steel plate on the exit side of the rolling mill. There is a two-dimensional laser scanner on the entry side of the rolling mill, which can measure the height distribution in the width direction of the mild steel sheet. The distance between the straight line connecting both ends in the width direction of the mild steel plate and the center in the width direction is defined as C warp, and the inclination of the straight line connecting both ends in the width direction of the mild steel plate in the horizontal direction is defined as twist. Based on the actual results of the coil that could be rolled without rolling, it was decided that a C warp of 20 mm or more and a twist of 0.05 rad or more were judged to be signs of throttle generation. Both the C warp and the twist were measured, and when there was a sign of the occurrence of drawing, the work roll bender was operated to press down the central portion of the mild steel plate in the width direction. When there was no sign of drawing, the work roll bender was operated so that the shape of the rolled mild steel plate measured by the output flatness meter was as flat as possible. As a result of the experiment, in the conventional operation, 500 coils were rolled and drawing was generated with 3 coils, but by applying the present invention, 2500 coils were rolled and drawing was not generated.

[Example 2]
A mild steel plate having an inlet side plate thickness of 1.400 mm, an outlet side plate thickness of 1.386 mm, and a plate width of 1100 mm was rolled. The set values of the unit tension were 20 MPa on the entry side and 40 MPa on the exit side. As the rolling mill, the rolling mill shown in FIG. 1 was used. The work roll diameter of the rolling mill is Φ450 mm, and the backup roll diameter is Φ1200 mm. The rolling mill is equipped with a work roll bender as a shape control actuator. There is a roll-type flatness meter on the exit side of the rolling mill, which can measure the shape of the mild steel plate on the exit side of the rolling mill. There is a two-dimensional laser scanner on the entry side of the rolling mill, which can measure the height distribution in the width direction of the mild steel sheet. I-Unit was used as an index showing the degree of ear elongation. I-Unit is calculated as a relative value with the elongation at the center in the width direction as zero, and the I-Unit at the end in the width direction is 50 or more based on the actual results of the coil that could be rolled without drawing in the past. Was determined to be a sign of occurrence. When there was a sign of drawing, the work roll bender was operated to press down the central part of the mild steel plate in the width direction. When there was no sign of drawing, the work roll bender was operated so that the shape of the rolled mild steel plate measured by the output side flatness meter was as flat as possible. As a result of the experiment, in the conventional operation, 500 coils were rolled and drawing was generated with 3 coils, but by applying the present invention, 1000 coils were rolled and drawing was not generated.

Although the embodiment to which the invention made by the present inventors has been applied has been described above, the present invention is not limited by the description and the drawings which form a part of the disclosure of the present invention according to the present embodiment. That is, other embodiments, examples, operational 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.

1 Roller 2a, 2b Reel 3a, 3b Work roll 4a, 4b Backup roll 5 Laser scanner 6 Flatness meter 7 Control device S Metal strip

Claims (3)

A calculation step for calculating the twist, C warp, and ear elongation of the metal strip on the entry side of the rolling mill, and
When at least one of the twist, C warp, and ear elongation of the metal band calculated in the calculation step is equal to or more than a predetermined threshold value, the rolling amount at the center portion in the width direction is relative to the rolling amount at the end portion in the width direction of the metal band. Rolling control step to increase the size
A method for controlling rolling of a metal strip, which comprises. A measuring means for measuring the height distribution in the width direction of the metal strip on the entrance side of the rolling mill, and
The twist, C warp, and ear elongation of the metal band on the entrance side of the rolling mill are calculated from the height distribution in the width direction of the metal band measured by the measuring means, and the calculated twist, C warp, and C warp of the metal band are calculated. When at least one of the ear elongations is equal to or more than a predetermined threshold value, a control means for increasing the rolling amount of the central portion in the width direction relative to the rolling amount of the rolling edge in the width direction of the metal band.
A rolling control device for a metal strip, which comprises. A method for manufacturing a metal strip, comprising a step of manufacturing the metal strip by using the method for controlling rolling of the metal strip according to claim 1.

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