JP2002096103A - Method of detection of plate deflection on plate rolling and method of preventing plate deflection on plate rolling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a plate deflection and prevent the plate deflection without being influenced by the ambient environment. SOLUTION: Detecting a rotational speed of an upper roll and a lower roll from the rotational speed of motors 3U and 3L individually, an elongation difference in the longitudinal direction between the upside surface and downside surface of the rolled material L is detected by means of integrating these speed differences. Since the plate deflection of the rolled material L is formed by the elongation difference between the upside surface and the downside, the plate deflection and its degree become possible to be detected based on the distribution conditions of the elongation difference. Consequently, detecting the direction of plate deflection formed toward upside or downside and the degree of its formation based on the distributed conditions of the elongation difference and by means of correcting the rotational speed of motors 3U and 3L in a manner of suppressing the plate deflection, the elongation difference between the upside surface and the downside is suppressed, so that the plate deflection is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate rolling mill in which upper and lower work rolls are driven by separate electric motors, which detects a plate warpage generated in a rolling process and prevents the sheet warpage. The present invention relates to a method for detecting a sheet warpage in thick plate rolling and a method for preventing sheet warpage in thick plate rolling.

[0002]

2. Description of the Related Art Conventionally, in plate rolling, a steel sheet is rolled to a predetermined thickness by a reversible rolling mill. At this time, warpage occurs immediately after the steel sheet bites, which adversely affects the operation. Causes of this warpage include a temperature difference between the upper and lower surfaces of the steel sheet, a speed difference between the upper and lower work rolls due to the electric motor impact drop, and the most dominant are the motors provided on the upper and lower work rolls, respectively. It is a speed impact drop.

[0003] The speed impact drop is
It refers to a phenomenon in which the rotational speed of the upper and lower work rolls temporarily decreases when a steel sheet is bitten. In general, when the upper and lower work rolls are driven by separate electric motors, as shown in FIG. 2, a mechanical shaft that mechanically couples the upper and lower work rolls 1U and 1L and the respective electric motors 3U and 3L for driving them. 23U,
The length of 23L differs between upper and lower sides.

As a result, a difference occurs in the spring constant of the mechanical shaft,
The speed drop at the end of the work roll when the steel sheet bites, and the behavior at the time of the speed return differ between the upper and lower electric motors. For this reason, a difference occurs in the spring constant of the machine shaft, a speed difference occurs between the upper and lower work rolls immediately after the steel sheet is bitten, and a difference occurs in the elongation on the upper surface and the lower surface until a certain period of time elapses and the speed difference disappears. Then, the steel material after rolling is warped.

As a method for preventing this warpage, for example,
A warp detector for detecting warpage is provided on one side of the rolling mill, the curvature detector detects the curvature of the warpage generated in the steel sheet, and suppresses the curvature according to the curvature. Methods for adjusting the rotation speed of the work roll and the like have been proposed.

[0006]

As the warp detector, for example, one using an optical detector as described in Japanese Patent Application Laid-Open No. 60-071902 is known. However, in the method of detecting the sheet warpage using the optical detector as described above, it is difficult to obtain the measurement accuracy due to the influence of the surrounding environment such as steam generated around the rolling mill or the temperature and humidity. . Further, since the detected value itself varies depending on the environment, it is difficult to perform control using the detected value.

Further, in order to enable control of warpage using an optical detector, it is necessary to reduce environmental fluctuations. However, in order to realize this, equipment costs are increased. Problem. Accordingly, the present invention has been made in view of the above-mentioned conventional unsolved problem, and a method and a method for detecting sheet warpage in thick sheet rolling capable of performing warpage control without being affected by the surrounding environment. An object of the present invention is to provide a method for preventing sheet warpage in sheet rolling.

[0008]

According to a first aspect of the present invention, there is provided a method for detecting sheet warpage in thick plate rolling, wherein upper and lower work rolls are driven by separate electric motors. A plate warpage detection method in thick plate rolling in which a material is rolled, wherein a difference in rotation speed between the upper and lower work rolls is detected from the speed of each electric motor that drives the upper and lower work rolls, and the difference in rotation speed is determined. The time difference is integrated in the longitudinal direction of the material to be rolled to detect a difference in elongation between the upper surface and the lower surface of the material to be rolled in the longitudinal direction. This is characterized in that the board warpage is detected.

According to the first aspect of the present invention, the rotational speeds of the upper and lower work rolls are detected from the rotational speeds of the electric motors that individually drive the upper and lower work rolls, and the rotational speed difference between the upper and lower work rolls is detected from these. Is detected, and the difference between the rotational speeds of the upper and lower work rolls is integrated in the longitudinal direction of the material to be rolled. The integral of this rotational speed difference in the longitudinal direction is
This is the difference in elongation in the longitudinal direction between the upper surface and the lower surface of the material to be rolled.

Here, for example, the higher the rotation speed of the upper surface, the greater the extension of the upper surface, so that the board warps downward. Conversely, if the rotation speed of the lower surface is faster, the lower surface extends. Is increased, so that the board warps upward. Therefore, it is possible to detect the state of occurrence of sheet warpage from the distribution state of the difference in elongation in the longitudinal direction. The method for preventing sheet warpage in thick sheet rolling according to claim 2 is a method for controlling sheet warpage in thick sheet rolling in which upper and lower work rolls are driven by separate electric motors to roll a material to be rolled. Detecting the rotational speed difference between the upper and lower work rolls from the speed of each electric motor driving the upper and lower work rolls, integrating the rotational speed difference over time in the longitudinal direction of the material to be rolled, and detecting the upper surface of the material to be rolled. And detecting the difference in elongation of the lower surface in the longitudinal direction, and detecting the sheet warpage of the material to be rolled based on the distribution state of the difference in elongation in the longitudinal direction of the material to be rolled, so as to suppress the warpage. It is characterized by adjusting conditions.

According to a third aspect of the present invention, there is provided a method for preventing warpage in thick plate rolling according to the second aspect, further comprising: The method is characterized in that rolling conditions in a pass subsequent to the pass in which the difference in elongation is detected are adjusted. Further, the method for preventing sheet warpage in thick plate rolling according to claim 4 is the same as the method for preventing sheet warpage in thick plate rolling according to claim 2 or 3, wherein the method is the same as that for a material to be rolled that has detected the difference in elongation. The present invention is characterized in that rolling conditions for a material to be rolled having warpage characteristics are adjusted.

According to a fifth aspect of the present invention, there is provided a method for controlling sheet warpage in thick plate rolling, wherein upper and lower work rolls are driven by separate electric motors to roll a material to be rolled. Detecting the rotational speed difference between the upper and lower work rolls from the speed of each electric motor driving the upper and lower work rolls, integrating the rotational speed difference over time in the longitudinal direction of the material to be rolled, and Detecting the difference in elongation between the upper surface and the lower surface of the material in the longitudinal direction, detecting the sheet warpage of the material to be rolled based on the distribution of the difference in elongation in the longitudinal direction of the material to be rolled, and suppressing the rolling process. Is characterized in that the pressure reduction conditions of the leveler used in the downstream process of (1) are adjusted.

According to the second to fifth aspects of the present invention, the rotational speeds of the upper and lower work rolls are detected from the rotational speeds of the electric motors that individually drive the upper and lower work rolls. When the rotational speed difference is detected,
The difference between the rotational speeds of the upper and lower work rolls is integrated in the longitudinal direction of the material to be rolled. The integral of the rotational speed difference in the longitudinal direction is the difference in longitudinal extension between the upper surface and the lower surface of the material to be rolled.

Here, for example, if the rotation speed of the upper surface is higher, the elongation of the upper surface is correspondingly increased, so that a downward warpage occurs. Conversely, if the rotation speed of the lower surface is higher, the elongation of the lower surface is correspondingly increased. Increases, so that the board warps upward.
Therefore, it is possible to detect the occurrence state of the plate warpage such as in which direction the plate warpage is generated and how much the plate warpage is generated from the distribution state of the difference in longitudinal elongation, and based on the occurrence state of the plate warpage, By adjusting the rolling conditions so as to suppress it, it is possible to prevent sheet warpage of the material to be rolled.

For example, if the rolling conditions are changed in the pass where the difference in elongation is detected, it is possible to suppress the degree of warpage of the sheet, and in the next pass in which the difference in elongation is detected. If the rolling conditions are changed, it is possible to correct the sheet warpage generated in the previous pass. The rolled material having the same warpage characteristics as the material to be rolled, which is different from the material to be rolled for which the differential elongation was detected, that is, the same material as the material to be rolled for which the differential elongation was detected. When rolling is performed on a material to be rolled having a similar shape, when the material to be rolled is rolled, the distribution of the difference in elongation is the same as the distribution of the difference in elongation in the material to be rolled for which the difference in elongation was detected. Since the situation is predicted, if the rolling conditions are adjusted in advance so as to suppress the warpage in accordance with the distribution state of the difference in elongation detected earlier, the occurrence of the warpage can be prevented.

[0016] Further, the rolling condition of the leveler used in the downstream process of the rolling process is changed so as to suppress the sheet warpage based on the sheet warpage predicted from the distribution state of the detected difference in elongation, thereby reducing the rolling process. The warpage of the material to be rolled caused by the above is corrected.

[0017]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing a schematic configuration of a control system of a reversible rolling mill to which a method for detecting sheet warpage in thick plate rolling and a method for preventing sheet warpage in thick plate rolling according to the present invention.

In the drawing, 1U and 1L are upper and lower work rolls in a reversible rolling mill, 2U and 2L are upper and lower backup rolls, and the work rolls 1U and 1L are driven by electric motors 3U and 3L, respectively. These motors 3
U, 3L are controlled to a predetermined speed by mill speed adjusters 5U, 5L via drive circuits 4U, 4L configured to control the rotation speed of the electric motors 3U, 3L in forward and reverse directions and to control the rotation speed thereof. This mill speed controller 5U, 5L
Are pulse generators (PLs) provided in the motors 3U and 3L.
G) The speed of the motors 3U and 3L is calculated based on the pulse signals detected by the 6U and 6L, and the speed control is performed so that the calculated motor speed becomes the reference speed input from the mill speed reference calculation circuit 7.

The mill speed reference calculation circuit 7 calculates a reference speed for driving the upper and lower work rolls 1U and 1L,
This is output to the mill speed adjusters 5U and 5L, and when a correction signal for adjusting the difference in elongation is input from the plate warpage adjustment device 11 described later, the reference speed is corrected according to the correction signal. A corrected reference speed for the upper work roll and a corrected reference speed for the lower work roll are calculated and output to the corresponding mill speed controllers 5U and 5L.

The mill speed controllers 5U and 5L control the motors 3U and 3L based on the calculated motor speeds, and output the motor speeds to the corresponding roll speed calculation devices 8U and 8L. This roll speed calculator 8U,
In 8L, the rotation speeds of the work rolls 1U and 1L are calculated based on the motor speed and the rolling torque. The rolling torque is, for example, a torque at a biting end of the upper and lower work rolls, which is theoretically or empirically detected based on a heating condition or a rolling condition.

The upper and lower roll speeds detected by the roll speed calculators 8U and 8L are output to a calculation circuit 9, where the lower roll speed is subtracted from the upper roll speed to detect the difference between the upper and lower roll speeds. The vertical roll speed difference is output to the vertical extension difference calculation device 10. In the vertical elongation difference calculating device 10, the vertical roll speed difference is integrated over time in the longitudinal direction of the material L to be rolled, and this is output to the sheet warpage adjusting device 11.

The board warpage adjusting device 11 determines whether an upward warpage or a downward warpage has occurred based on the input time integral value, that is, a difference in extension between the upper surface and the lower surface. Then, based on the result of the determination, a correction signal for correcting the reference speed for suppressing plate warpage is output to the mill speed reference arithmetic circuit 7. The work rolls 1U and 1L and the electric motors 3U and 3L are connected, for example, as shown in FIG.
U and 1L are connected by being mechanically connected via couplings 22U and 22L and spindles 21U and 21L.

FIG. 3 shows work rolls 1U and 1L and electric motor 3
U and 3L are represented by a mechanical model. The reversible rolling mill shown in FIG. 1 can be described by a two-mass model as shown in FIG. Can be detected based on this model. When a gear is included, as shown in FIG.
It can be described by a mass model.

Next, the operation of the above embodiment will be described based on the processing in the plate warpage adjusting device 11. Now, when the reference speed of each electric motor 3U, 3L is set in the mill speed reference arithmetic circuit 7, the mill speed adjusters 5U, 5L control the drive circuits 4U, 4L to drive the electric motors 3U, 3L. With the rotation of the electric motors 3U and 3L, a pulse generator 6U,
A pulse signal is generated from 6L, and a mill speed controller 5U,
In 5L, the rotation speeds of the motors 3U and 3L are calculated based on the pulse signals, and the drive circuits 4U and 4L are driven so that the motor speed matches the reference speed specified by the mill speed reference calculation circuit 7.
By controlling L, the electric motors 3U and 3L rotate at the designated reference speed.

The motor speeds detected by the mill speed controllers 5U and 5L are output to roll speed calculators 8U and 8L, and the upper roll speed and the lower roll speed are detected.
When the rolled material L is not engaged, the speed difference between the upper roll speed and the lower roll speed is substantially zero, and the difference in elongation calculated by the vertical elongation difference calculating device 10 is substantially zero. The correction signal detected in step (1) becomes substantially zero, and the reference speed calculated by the mill speed reference calculation circuit 7 is not corrected.

Therefore, motors 3U and 3L continuously rotate at the reference speed. From this state, work roll 1
U, 1L bites the material L to be rolled, and when this causes a speed impact drop on the upper and lower motors 3U, 3L,
The upper roll speed and the lower roll speed are detected by the roll speed calculators 8U, 8L based on the pulse generators 6U, 6L and the biting torque detected based on rolling conditions and the like in advance. Since the speed impact drop occurs in 3L, there is a difference between the upper and lower roll speeds. Therefore, when the difference between the upper and lower roll speeds is integrated by the upper and lower elongation difference calculating device 10, a difference in elongation occurs between the upper and lower portions of the material L to be rolled.

In the plate warpage adjusting device 11, for example, at the time of biting, that is, the distribution of the difference in elongation in the longitudinal direction from the time when a vertical elongation difference occurs to the elapse of a predetermined time, the amount of warpage of the plate warp, the plate warp Of the occurrence of the warp direction, etc., is detected, and based on this, the speed correction values of the electric motors 3U and 3L for the upper work roll and the lower work roll that can suppress the plate warpage are detected, and this is used as a correction signal. Output to the mill speed reference circuit 7. The detection of the speed correction value is performed, for example, by previously detecting and storing the correspondence between the state of occurrence of plate warpage and the speed correction values of the upper work roll and lower work roll motors 3U and 3L that can suppress the warpage. , Based on this correspondence information.

FIG. 4 shows the variation of the difference between the upper and lower roll speeds during the biting. In the section "A", the rotation speed of the upper work roll 1U is higher than that of the lower work roll 1L. In the section “B”, in which the lower work roll 1L has a higher rotation speed, the lower face has a larger elongation, and an upward warp is generated in a section where the upper surface is larger and the upper surface is larger and the downward warpage is generated. This is the section that occurs.

As shown in FIG. 4, the speed difference between the upper and lower rolls is greatest when biting, and thereafter, the section (A) in which the upper roll has a higher rotation speed and the section in which the lower roll has a higher rotation speed. While repeating (B), the speed difference converges. Therefore, it is possible to predict which degree of upward warpage or downward warpage will occur as a result from the distribution of the difference in elongation. That is, in FIG. 4, when the sum of the areas of the sections A is larger than the sum of the areas of the sections B, it can be predicted that the warpage occurs, and it is predicted that the larger the difference between them, the larger the amount of the warpage. can do. Conversely, when the sum of the areas of the sections A is smaller than the sum of the areas of the sections B, it can be predicted that the warpage has occurred, and it can be predicted that the larger the difference between them, the larger the amount of the warpage. it can.

Therefore, for example, a section in which a difference in elongation affecting the state of occurrence of sheet warpage occurs, that is, in the case of FIG. 4, for example, until both the speed difference in section A and section B become a predetermined value or less. A predetermined time that can be considered to have elapsed is detected in advance, and the state of occurrence of sheet warpage is predicted based on the distribution state of the difference in elongation from the time of biting until the required time elapses. . Then, when a correction signal capable of suppressing this is detected and output to the mill speed reference calculation circuit 7, the mill speed reference calculation circuit 7 calculates the upper work roll and the lower work roll based on the notified correction signal. The reference speed of the electric motors 3U and 3L is corrected, and the corrected reference speed corrected according to the difference in elongation is used as the mill speed controller 5
Output to U and 5L.

For example, when it is predicted that an upward warpage has occurred, a correction is made so that the rotation speed of the lower work roll 1L is increased by an amount corresponding to the amount of the warp, and conversely, a downward warp occurs. When it is predicted that the upper work roll 1
Correction is performed so that the rotation speed of U is increased by an amount corresponding to the difference in elongation. Thereby, mill speed controllers 5U, 5L
Then, the electric motors 3U, 3U
Since L is driven, the upper and lower work rolls 1U and 1L are driven so as to suppress the board warpage, and the board warpage is suppressed.

At this time, since the upper and lower roll speeds are detected from the rotational speeds of the electric motors 3U and 3L, the difference in elongation is detected based on the detected roll speeds, and the warpage is predicted from the distribution state. Since the board warpage is predicted based on the rotation speeds of the electric motors 3U and 3L which are not affected by the heat, the board warpage can be accurately predicted regardless of the environmental conditions. Therefore, based on the detected plate warpage, the speed control of the electric motors 3U and 3L is performed so as to suppress the plate warpage, so that the plate warpage can be accurately suppressed.

At this time, the occurrence state of the detected sheet warpage is stored, and the sheet warpage is not corrected in the pass in which the difference in elongation has been detected. By correcting the warpage based on the occurrence state of the warp, the warpage of the plate generated in the pass where the difference in elongation is detected may be corrected in the next pass.

The correction of the rolling conditions in the next pass is as follows:
The adjustment may be performed by adjusting the rotation speeds of the electric motors 3U and 3L.
The rolling conditions of the upper and lower work rolls 1U and 1L may be adjusted. For example, if there is a bow,
The rotation speed of the upper work roll is corrected so as to be larger than the rotation speed of the lower work roll, or the pass line, that is, the sheet pressure center of the material to be rolled shown in FIG. If the correction is performed so as to increase the position Lp, the warpage can be reduced.

Further, the state of occurrence of sheet warpage in, for example, the first pass with respect to the material to be rolled L is stored. When rolling is performed on a material to be rolled L ′, which is predicted to have the same warpage as that of the material to be rolled L, the sheet warpage in the material to be rolled L is stored. The rolling conditions may be corrected based on the state of occurrence of, and rolling may be performed based on the corrected rolling conditions. The correction of the rolling conditions may be performed by adjusting the rotation speeds of the electric motors 3U and 3L.
May be adjusted. in this case,
For example, during rolling of the rolled material L ′, in a section where warpage has occurred in the rolled material L that has been rolled earlier, the rotation speed of the upper work roll is set to be larger than the rotation speed of the lower work roll. If the correction is made or the center position of the roll gap is corrected so as to increase the pass line, that is, the plate thickness center position of the material L 'to be rolled, the warpage can be reduced.

Further, in the above embodiment, the case where the warpage of the sheet is corrected in the rolling step has been described. However, the present invention is not limited to this. For example, the correction is performed by a leveler (not shown) in the downstream step of the rolling step. You may do so. That is, as shown in FIG. 5, for example, the occurrence state of the board warpage estimated based on the occurrence state of the difference in elongation in the first pass is stored in the storage device 11a, and based on the occurrence state of the board warpage, A reduction pattern that can suppress this is determined, and this reduction pattern is set in the leveler reduction control device 12 that adjusts the reduction amount of the leveler. Then, the leveler rolling-down control device 12 may adjust the rolling-down amount of the leveler according to the set rolling-down pattern, so that the leveling of the material L to be rolled in the rolling process is corrected by the leveler.

The above-mentioned rolling pattern is, for example, a change in the magnitude of the difference in elongation so as to increase the rolling amount in a section where the detected difference in elongation is large and to reduce the rolling amount in a section where the difference in elongation is small. The rolling reduction may be controlled accordingly. In addition, when the detected amount of warpage is excessively large, if the roll opening of the leveler is small, the rolled material may collide with a roll or the like, and may damage the equipment. According to the present invention, the amount of warpage is detected in advance, and the roll opening on the leveler entering side is adjusted sufficiently in accordance with the amount of warpage to sufficiently open the rolled material. Can prevent equipment damage.

[0038]

As described above, according to the first aspect of the present invention,
According to the invention according to claim 5, the sheet warpage of the material to be rolled is detected by detecting the difference in the rotational speed of the upper and lower work rolls from the speed of the electric motor and detecting the difference in the vertical elongation of the material to be rolled based on the difference. Since the detection is performed, the warpage of the material to be rolled can be accurately detected without being affected by the surrounding environment.

Further, based on the sheet warpage detected in this way, by changing the rolling conditions or the rolling down condition of the leveler in a process downstream from this, it is possible to suppress the sheet warpage. Rolled material can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a control system of a reversible rolling mill to which the present invention is applied.

FIG. 2 is an explanatory diagram showing a connection state between an electric motor and a work roll.

FIG. 3 is a mechanical model showing an electric motor and a work roll.

FIG. 4 is an explanatory diagram showing a fluctuation state of a vertical roll speed difference due to biting.

FIG. 5 is a block diagram showing a schematic configuration of a control system of a reversible rolling mill, showing another example to which the present invention is applied.

[Explanation of symbols]

 1U, 1L work roll 2U, 2L backup roll 3U, 3L electric motor 4U, 4L drive circuit 5U, 5L mill speed controller 6U, 6L pulse generator 7 mill speed reference calculation circuit 8U, 8L roll speed calculation device 9 calculation circuit 10 up and down Elongation difference calculation device 11 Board warpage adjustment device

Claims (5)

[Claims] 1. A method for detecting warpage in plate rolling in which upper and lower work rolls are driven by separate electric motors to roll a material to be rolled, wherein a speed of each of the electric motors driving the upper and lower work rolls is controlled. Detecting the rotational speed difference between the upper and lower work rolls, detecting the difference in longitudinal elongation between the upper surface and the lower surface of the material to be rolled by integrating the rotational speed difference in the longitudinal direction of the material to be rolled, A method for detecting warpage in thick rolling, wherein the warpage of the material to be rolled is detected based on the distribution of the difference in elongation in the longitudinal direction of the material to be rolled. 2. A method for controlling sheet warpage in thick plate rolling in which upper and lower work rolls are driven by separate electric motors to roll a material to be rolled, wherein a speed of each of the motors driving the upper and lower work rolls is controlled. Detecting the rotational speed difference between the upper and lower work rolls, detecting the difference in longitudinal elongation between the upper surface and the lower surface of the material to be rolled by integrating the rotational speed difference in the longitudinal direction of the material to be rolled, In plate rolling, characterized in that rolling conditions in the plate rolling are adjusted to detect and warp the sheet warpage of the material to be rolled based on the distribution of the difference in elongation in the longitudinal direction of the material to be rolled. Plate warpage prevention method. 3. The prevention of sheet warpage in thick plate rolling according to claim 2, wherein a rolling condition in a pass in which the differential elongation is detected or a rolling condition in a pass next to the pass in which the differential elongation is detected is adjusted. Method. 4. A method for preventing sheet warpage in thick plate rolling according to claim 2 or 3, wherein rolling conditions for a material to be rolled having the same warpage characteristics as the material to be rolled for which the difference in elongation has been detected are adjusted. . 5. A method for controlling sheet warpage in thick plate rolling in which upper and lower work rolls are driven by separate electric motors to roll a material to be rolled, wherein a speed of each of the motors driving the upper and lower work rolls is controlled. Detecting the rotational speed difference between the upper and lower work rolls, detecting the difference in longitudinal elongation between the upper surface and the lower surface of the material to be rolled by integrating the rotational speed difference in the longitudinal direction of the material to be rolled, Based on the distribution of the difference in elongation in the longitudinal direction of the material to be rolled, the sheet warpage of the material to be rolled is detected, and a rolling-down condition of a leveler used in a downstream process of the rolling process is adjusted so as to suppress the warpage. A method for preventing sheet warpage in thick plate rolling.