JPH10263636A - Automatic controller for plate thickness by hydraulic pressure in rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain enough rolling torque, and to avoid a deterioration in a rolling precision and the damage of a rolling equipment, caused by impact rolling torque while securing the responsiveness of the necessary control of the plate thickness by the hydraulic pressure, which corresponds to a rolling state. SOLUTION: When opening an opening/closing valve 12 and closing opening/ closing valve 13 and opening/closing valve 14, the hydraulic pressure from a servo valve 9B is directly supplied to a hydraulic pressure AGC cylinder 7, the responsiveness for controlling the hydraulic pressure AGC is improved, and the precision of the plate thickness is improved. On the other hand, when closing the opening/closing valve 12 and opening the opening/closing valves 13 and 14, since the hydraulic pressure from the servo valve 9B is applied via a hydraulic pressure buffer tank 15, an oil capacity is increased. In this way, the impact rolling torque at the time of rolling, which is controlled by a hydraulic pressure AGC cylinder 7, is relaxed. According to a control state, by changing over the opening/closing valves 12 to 14, optimum rolling is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic hydraulic thickness control apparatus for a rolling mill in which a servo valve is arranged close to a hydraulic cylinder in order to improve the control response of the hydraulic thickness control. In addition to obtaining sufficient rolling torque while ensuring the required hydraulic plate thickness control response in accordance with
The present invention relates to a hydraulic automatic thickness control apparatus for a rolling mill capable of avoiding a reduction in rolling accuracy and damage to rolling equipment due to impact rolling torque.

[0002]

2. Description of the Related Art The thickness control technology in rolling has rapidly advanced since the introduction of hydraulic automatic thickness control, and has achieved high thickness accuracy (automatic thickness control is hereinafter simply referred to as AGC). ). In particular, high performance and large capacity servo valves have been developed and put into practical use, and responsiveness has been obtained.
From the lock-on AGC to the absolute value AGC, or the monitor AGC (FB-AGC) using the information of the thickness sensor
It is becoming multifunctional.

[0003] In the hydraulic control for AGC, various devices have recently been devised. For example,
In 45005, two types of servo valves having different characteristics are selectively used in order to control the rolling torque of a rolling roll. Servo valves tend to increase the control pressure error as the maximum pressure increases. For this reason,
In -45005, two types of servo valves having different control pressures are selectively used to improve pressure control accuracy.

In Japanese Patent Laid-Open Publication No. Sho 50-131656, a servo valve is directly mounted on a hydraulic AGC cylinder to further improve responsiveness. By improving the responsiveness in this way, it is possible to achieve a significant improvement in the thickness accuracy.

[0005]

However, when the servo valve is directly mounted on the cylinder as described above, the rolled material is fed, and the impact rolling torque generated when the leading end of the rolled material is bitten by a rolling mill is remarkably increased. There is a problem that it increases.

[0006] This impact rolling torque is controlled by the hydraulic valve AG
When not directly attached to the C cylinder, the oil capacity from the servo valve to the hydraulic AGC cylinder via a predetermined pipe is considerably large, so that the oil was buffered and absorbed by the compression of the oil. On the other hand, when the servo valve is directly attached to the hydraulic AGC cylinder, the above oil capacity is substantially limited to the inside of the hydraulic AGC cylinder and significantly decreases, and the buffering effect of the impact rolling torque at the time of biting by oil compression becomes small. Would. If the impact rolling torque at the time of biting is large, the drive system of the rolling mill may be damaged in some cases, and a large rolling torque cannot be set to prevent such damage, thereby lowering the rolling efficiency. There is a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and a sufficient rolling torque can be obtained while a sufficient rolling torque can be obtained while ensuring the required responsiveness of hydraulic plate thickness control according to the rolling situation. It is an object of the present invention to provide a hydraulic AGC device in a rolling mill that can avoid a reduction in rolling equipment due to a drop or an impact rolling torque.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a hydraulic automatic plate thickness control device for a rolling mill in which a servo valve is arranged close to a hydraulic cylinder in order to improve the control response of the hydraulic plate thickness control. A bypass hydraulic circuit, and a hydraulic pipe between the servo valve and the hydraulic cylinder, further comprising an oil capacity increasing valve for selectively connecting the bypass hydraulic circuit. In order to increase the oil capacity of the hydraulic piping, the above-mentioned problem has been solved by operating the oil capacity increasing valve so as to connect the bypass hydraulic circuit.

In the above-mentioned hydraulic AGC apparatus for a rolling mill, at least when the rolling mill bites the leading end of the rolled material, the oil capacity increasing valve is operated so as to connect the bypass hydraulic circuit. When improving control responsiveness, the oil capacity adjustment control device that operates the oil capacity increase valve to release the connection is provided to prevent damage to the rolling equipment at the time of biting the tip of the rolled material. It is something to do.

Hereinafter, the operation of the present invention will be briefly described.

Here, a general explanation of the general thick-rolling will be given. Plate rolling is a forming rolling pass, a width rolling pass,
In general, the rolling process is made up of three rolling processes, ie, a thickness rolling pass and a thickening rolling pass. In the plate rolling, a 90-degree turn is performed between these rolling processes, and therefore, rolling is performed according to the procedures of steps A1 to A5 listed below.

A1. Forming rolling pass: Rolling for adjusting the shape and surface properties of the slab, and does not generate a large rolling torque.

A2. 90-degree turning: A 90-degree turning is performed by rotation about a rotation axis in the normal direction of the surface of the rolled material.

A3. Tender rolling pass: a process of rolling a rolled material to a product width. After the forming and rolling pass, the rolled material length becomes the width of the tentative rolling pass by turning by 90 degrees, so that in this tentative rolling pass, the dimension in the width direction of the rolling is increased, and therefore the steady rolling torque is increased. In addition, since the plate thickness is large, there is no upper limit of the rolling reduction (rolling torque upper limit) related to crown shape control in the thickness rolling pass described below. It is common to improve the rolling efficiency. In addition, since the steady rolling torque is large in this tentering rolling pass, the above-described impact rolling torque generated at the time of biting into the leading end of the rolled material increases, which may cause a problem such as damage to rolling equipment. is there.

A4. 90 degree turning: The object is turned 90 degrees again.

A5. Thickening rolling pass: In this thickening rolling pass, if rolling is performed with an excessively large rolling load, the deflection of the rolling roll increases and the crown shape deteriorates. As described above, in controlling the crown shape, the upper limit of the rolling reduction (the upper limit of the rolling torque) is present in this thickening rolling pass. Therefore, no large rolling torque is generated. Alternatively, a large rolling torque cannot be applied.

Therefore, as described above, the problem of the impact rolling torque in the thick plate rolling becomes a problem particularly in the tentering rolling bus. In order to prevent the drive system of the rolling equipment from being damaged, the rolling torque must be reduced, and the rolling efficiency of tentering rolling, which must reduce the number of rolling passes with a large rolling torque, is reduced. is there.

The present invention is not limited to plate rolling, but in plate rolling or the like, a specific rolling mill can be used.
Even in a series of rolling operations for one rolled material, there are special situations such as a rolling state such as a rolling torque fluctuating and a biting end of the rolled material where an impact torque is generated.

For this reason, according to the present invention, in order to improve the responsiveness of the thickness control, in a hydraulic automatic thickness control device in a rolling mill in which a servo valve is disposed close to a hydraulic cylinder, a bypass hydraulic circuit having a predetermined oil capacity; An oil capacity increasing valve for selectively connecting the bypass hydraulic circuit is newly provided in a hydraulic pipe between the servo valve and the hydraulic cylinder. Further, in the present invention, when the impact rolling torque as described above is increased, such as when the leading end of the rolled material is bitten by a rolling mill, in order to increase the oil capacity of a hydraulic pipe between the servo valve and the hydraulic cylinder, The oil volume increasing valve is operated so that the bypass hydraulic circuit is connected.

As described above, in the present invention, if the bypass hydraulic circuit is selectively connected, the impact rolling torque can be reduced. On the other hand, if the connection is released, the thickness control response can be improved. Therefore, it is possible to obtain a sufficient rolling torque while securing the necessary responsiveness according to the rolling situation, and to avoid a reduction in rolling accuracy and damage to the rolling equipment due to the impact rolling torque.

Here, an index TAF (torque amplification factor) indicating the degree of influence of the impact rolling torque is defined as follows.

TAF = (impact rolling torque) / (steady rolling torque) (1)

Here, the graph of FIG. 1 shows the impact rolling torque characteristics when the oil capacity of the hydraulic pipe between the servo valve for controlling the plate thickness and the hydraulic cylinder is 20 liters. FIG. 2 shows the impact rolling torque characteristics when the oil capacity is 90 liters.

First, referring to FIG.
This is a case where it is directly attached to the C cylinder. In FIG. 1, reference numeral B1 indicates an index TAF of 1.5. Reference numeral B2 indicates that the exponent TAF is 2. Accordingly, when the oil capacity is 20 liters, the distribution of the impact rolling torque with respect to the steady torque is such that the index TAF is in the range of 1.5 to 2.

On the other hand, FIG. 2 has a larger oil capacity than that of FIG. 1, and the servo valve is not directly attached to the hydraulic AGC cylinder, or the bypass hydraulic circuit is selectively connected by applying the present invention. This is the case. In FIG.
3 indicates the index TAF is 1, and reference numeral B4 indicates the index TAF is 1.5. When the oil capacity is 90 liters, the distribution of the impact rolling torque with respect to the steady torque is such that the index TAF is in the range of 1 to 1.5.

As is apparent from comparison between the graphs of FIGS. 1 and 2, when the oil capacity is increased, the index TAF indicating the degree of the influence of the impact rolling torque can be suppressed. Here, as is clear from the definition of the above equation (1), the index TA
It can be seen that when F is suppressed, the impact rolling torque can be suppressed even at the same steady rolling torque.

Therefore, according to the present invention, by selectively connecting the bypass hydraulic circuit to the hydraulic pipe between the servo valve and the hydraulic cylinder, the oil capacity of the hydraulic pipe can be selectively increased to reduce the impact rolling torque. Can be suppressed. Therefore, it is possible to avoid a reduction in rolling accuracy and damage to rolling equipment due to impact rolling torque. In order to particularly improve the thickness control response, the selective connection may be released.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 3 is a front view of a rolling mill to which the embodiment to which the present invention is applied is used.

This figure is a front view as seen from the entry side where the material to be rolled 1 is carried in. In a pair of opposing work rolls 2 for rolling the material 1 to be rolled, a backup roll 3 is arranged on the opposite side of the material 1 to be rolled. The rolling positions of the work roll 2 and the backup roll 3 are set by the screw 6 via the work roll chock 4 and the backup roll chock 5. The rolling torque is controlled by the hydraulic AGC cylinder 7 via the work roll chock 4 and the backup roll chock 5. The rolling mill targeted by the present embodiment is a four-stage tandem rolling mill provided with four rolling stands shown in FIG.

A servo valve 9 is almost directly attached to the hydraulic AGC cylinder 7. That is, the manifold block 8 to which the servo valve 9 is attached is directly attached to the hydraulic AGC cylinder 7. The servo valve 9 controls the oil pressure supplied from the oil pressure source 11 via the oil pressure pipe 10 so that the oil pressure A
The rolling torque by the GC cylinder 7 is controlled.

FIG. 4 is a hydraulic circuit diagram of the present embodiment.

As shown in FIG. 4, the servo valve 9 shown in FIG. 3 includes a servo valve 9A in which a spool for switching a hydraulic circuit is controlled by an electromagnetic solenoid, and a hydraulic valve controlled by the servo valve 9A. It has a two-stage configuration with a servo valve 9B that controls a spool that switches the hydraulic circuit. These servo valve 9A and servo valve 9
B has a PP line or P line connected to the hydraulic pressure source 11.
Line piping and T-line piping are connected.
The servo valve 9B is operated by the servo valve 9A. Further, the servo valve 9B controls the hydraulic AGC cylinder 7 by switching the hydraulic pressure from the hydraulic pressure source 11, and controls the rolling torque.

The hydraulic piping 10 between the servo valve 9B and the hydraulic AGC cylinder 7 is provided with opening / closing valves 12 to 14. These open / close valves 12 to 14 correspond to the oil capacity increasing valve of the present invention. One end of each of the opening / closing valves 13 and 14 is connected to a hydraulic buffer tank 15 corresponding to a bypass hydraulic circuit of the present invention. Here, the open / close valves 12 to 14 are opened and closed as described below, and the connection of the hydraulic pressure to the hydraulic buffer tank 15 is selectively performed.

C1. Open / close valve 12 is open and open / close valve 1
3 and 14 are closed: the hydraulic piping 10 from the servo valve 9B to the hydraulic AGC cylinder 7 is minimized, and the oil capacity of the hydraulic piping 10 is minimized. The control responsiveness of the hydraulic AGC is improved. On the other hand, the impact rolling torque at the time of biting the tip of the non-rolled material increases.

C2. Open / close valve 12 is closed and open / close valve 1
3 and 14 open: The hydraulic pressure from the servo valve 9B is not supplied to the hydraulic AGC cylinder 7 via the opening / closing valve 12. The hydraulic pressure from the servo valve 9B is bypassed via the open / close valve 14, the hydraulic buffer tank 15, and the open / close valve 13, and is supplied to the hydraulic AGC cylinder 7. Therefore, the substantial length of the hydraulic piping 10 from the servo valve 9B to the hydraulic AGC cylinder 7 is increased, and the substantial oil capacity of the hydraulic piping 10 is increased. Therefore, the control response of the hydraulic AGC is reduced. However, the impact rolling torque at the time of tipping of the material to be rolled or the like is reduced.

As described above, in the present embodiment, it is possible to set the two hydraulic supply paths of the selective connections C1 and C2. Therefore, according to the rolling situation and rolling requirements,
Opening / closing valves 12 to 14 are connected so as to be selective connection C1 when the control response of the AGC is to be improved, and are selectively connected C2 when it is desired to reduce the impact rolling torque.
Open and close.

For example, in the above-described thick plate rolling in steps A1 to A5, in the tentative rolling pass in step A3, there is a need to relax the impact rolling torque and increase the rolling reduction to increase the rolling efficiency as described above. . Therefore, in this tentering rolling pass, the selection connection C1 is set. In this tentering rolling pass, the material to be rolled 1 is turned by 90 degrees with respect to the final rolling direction, so that not only the effect of skid marks is small, but also the rolling speed is slow, and the final plate thickness accuracy is hardly affected. It does not affect. Therefore, even if the control response of the hydraulic AGC control is reduced as the selective connection C2 and the plate thickness accuracy is reduced, no problem occurs.

Next, in the thickening rolling pass in step A5 of the thick plate rolling described above, since the influence on the final thickness accuracy is great, the control response of the hydraulic AGC is improved,
It is necessary to improve the thickness accuracy. Therefore, the selection connection C1 is set in the thickness increasing rolling pass. In this thickening rolling pass, the rolling torque is suppressed to a small value as described above, so that the impact rolling torque is small even with the selective connection C1.

In a plurality of passes of the thickness-rolling rolling pass, when the thickness is large in the first half and it is necessary to increase the rolling torque to increase the rolling efficiency, the selective connection C2 may be set as necessary. .

As described above, in the present embodiment, by applying the present invention, the required hydraulic pressure AG according to the rolling situation
It is possible to obtain a sufficient rolling torque while securing the control responsiveness of C, and to avoid a reduction in rolling accuracy and damage to rolling equipment due to an impact rolling torque. The selective connection C2 is used even in a pass where a large rolling torque cannot be applied due to a limitation of the drive system strength due to a large impact rolling torque when the rolling material 1 is engaged in the rolling mill, such as a tentering rolling pass. As a result, the impact rolling torque can be reduced, and the rolling efficiency can be improved by increasing the rolling torque. For example, in a thickness rolling pass where plate thickness accuracy is required, a hydraulic pipe 10 extending from the servo valve 9B to the hydraulic AGC cylinder 7 is used.
The hydraulic capacity of the servo valve 9B can be minimized, and by taking advantage of the feature that the servo valve 9B is directly attached to the hydraulic AGC cylinder 7, control responsiveness of the hydraulic AGC can be improved and good plate thickness accuracy can be secured.

[0042]

According to the present invention, it is possible to obtain a sufficient rolling torque while securing the required response of the hydraulic plate thickness control according to the rolling condition, and to avoid a reduction in rolling accuracy and damage to rolling equipment due to an impact rolling torque.

[Brief description of the drawings]

FIG. 1 is a graph showing a characteristic of an impact rolling torque with respect to a steady torque when an oil capacity of a hydraulic pipe from a servo valve to a hydraulic cylinder is 20 liters.

FIG. 2 is a graph showing a characteristic of an impact rolling torque with respect to a steady torque when the oil capacity is 90 liters.

FIG. 3 is a front view of a rolling mill in which an embodiment to which the present invention is applied is used.

FIG. 4 is a hydraulic circuit diagram of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Rolled material 2 ... Work roll 3 ... Backup roll 4 ... Work roll chock 5 ... Backup roll chock 6 ... Hydraulic screw 7 ... Hydraulic AGC cylinder 8 ... Manifold block 9, 9A, 9B ... Servo valve 10 ... Hydraulic piping 11 ... Hydraulic power source 12-14: Open / close valve 15: Hydraulic buffer tank

Claims (2)

[Claims] 1. A hydraulic automatic plate thickness control device for a rolling mill in which a servo valve is arranged close to a hydraulic cylinder in order to improve control responsiveness of hydraulic plate thickness control, comprising: a bypass hydraulic circuit having a predetermined oil capacity; In the hydraulic piping between the valve and the hydraulic cylinder,
An oil capacity increasing valve for selectively connecting the bypass hydraulic circuit, wherein when the oil capacity of a hydraulic pipe between the servo valve and the hydraulic cylinder is increased, the bypass hydraulic circuit is connected. An automatic hydraulic thickness control device for a rolling mill, wherein the oil capacity increasing valve is operated. 2. The method according to claim 1, wherein at least when the rolling mill bites the leading end of the rolled material,
An oil volume adjustment control device that operates the oil volume increase valve to connect the bypass hydraulic circuit, while operating the oil volume increase valve so as to release the connection when improving the plate thickness control response. An automatic hydraulic thickness control device for a rolling mill, comprising: