JP3617461B2 - Hydraulic reduction method and hydraulic reduction device for rolling mill - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic reduction method and a hydraulic reduction device for a rolling mill in the steelmaking field such as the steel industry.
[0002]
[Prior art]
The roll reduction device of a plate rolling mill has come to adopt a hydraulic cylinder system with good responsiveness from an electric screw system, and inserts a rolling material between a pair of upper and lower rolling rolls, The rolled material is rolled by pushing up both end support boxes (roll chock) with a pair of hydraulic reduction cylinders. Such a control method of the hydraulic pressure reducing device is generally performed by the following two methods.
(1) Position control: a step of controlling the roll parallelism during the roll closing operation (operation of bringing the rolled material into contact with the roll) (2) Pressure control: a step of controlling the rolling force during rolling constant.
For example, in a continuous line that operates by joining the tail end of the preceding material and the tip of the subsequent material, when the joining point passes the rolling mill, the rolling roll is once opened, and the position control described above is performed after the joining point has passed. The rolling roll is closed while performing, and after the rolling roll and the rolled material are in contact with each other, rolling is performed again by adjusting the rolling force by the pressure control described above.
[0004]
FIG. 3 shows a conventional example of a hydraulic reduction device that uses a tuning cylinder for position control of a rolling roll. The rolling mill 1 has a pair of upper and lower rolling rolls 2 and 3, and hydraulic pressure reduction cylinders 4 a and 4 b are respectively incorporated under roll chocks at both ends of the lower rolling roll 3. The pair of hydraulic pressure cylinders 4a, the hydraulic circuit A connected to 4b, the position control hydraulic circuit is divided into A ₁ and the pressure control hydraulic circuit A _2, the position control at the time of the roll closing operation by the position control hydraulic circuit A ₁ (roll parallelism control) is performed, the pressure control during the rolling performed by the pressure control hydraulic circuit a _2.
[0005]
Position control hydraulic circuit A _1, in order from the hydraulic pressure source side, the electromagnetic directional control valve 10, and the tuning cylinder 11 is provided with a pair of logic valves 12a, 12b. The two oil passages 13 and 14 from the hydraulic source are branched on the rolling mill side, and the branched oil passages 13a and 13b are respectively connected to the head side (piston lower chamber) of the pair of hydraulic reduction cylinders 4a and 4b. The branched oil passages 14a and 14b are connected to the rod sides (piston upper chambers) of the pair of hydraulic reduction cylinders 4a and 4b, respectively.
[0006]
The tuning cylinder 11 is a cylinder capable of releasing an equal amount of hydraulic oil by providing two pistons on one rod, and oil passages 13a and 13b are connected to the two inlet ports and outlet ports thereof. . The logic valves 12a and 12b are valves that open with respect to the flow in both directions and are closed by an external operation, and are provided on the rolling mill side of the oil passages 13a and 13b, respectively. Further, an oil passage 15 for rapid roll opening operation is connected to the oil passage 13 between the electromagnetic direction switching valve 10 and the tuning cylinder 11, and the pilot operation reversely opened by the electromagnetic direction switching valve 16 is connected to the oil passage 15. A stop valve 17 is provided.
[0007]
The pressure control hydraulic circuit A ₂ includes a proportional electromagnetic relief pressure reducing valve 21 and an electromagnetic shut-off valve 22 in order from the hydraulic source side in the oil passage 20 from the hydraulic source. The branched oil passages 20a and 20b of the oil passage 20 are joined to the oil passages 13a and 13b, respectively. The proportional electromagnetic relief pressure reducing valve 21 is controlled by a pressure converter 23 provided in the oil passage 20b. The electromagnetic shut-off valve 22 is operated by a pressure switch 24 provided in the oil passage 13b.
[0008]
In the hydraulic circuit A having the above structure, if the preceding material P ₁ and the welding point J which joined subsequent material P ₂ closes the rolling rolls 2 and 3 through the rolling mill 1, an electromagnetic directional control valve 10 The hydraulic oil is supplied to the tuning cylinder 11 through the oil passage 13 by exciting the solenoid a. The oil amount of the two systems discharged from the tuning cylinder 11 is equal, and this equal amount of hydraulic oil is supplied to the head side of the hydraulic pressure reduction cylinders 4a and 4b through the logic valves 12a and 12b. It is possible to contact the rolled material while maintaining the level.
[0009]
Next, when the rolling roll 3 and the rolling material P come into contact with each other, the pressure on the head side of the hydraulic reduction cylinder 4a increases, and this is detected by the pressure switch 24, and the logic valves 12a and 12b are closed and the electromagnetic type that has been closed is closed. When the shut-off valve 22 is opened and the proportional electromagnetic relief pressure reducing valve 21 is operated, the control shifts to pressure control.
[0010]
Next, when the welding point J of the preceding material P ₁ and the subsequent material P ₂ approaches the rolling mill 1 and opens the rolling rolls 2 and 3, the hydraulic oil is excited by exciting the solenoid b of the electromagnetic direction switching valve 10. Supplyed to the rod side of the hydraulic pressure reduction cylinders 4a and 4b by the oil passage 14, the rolling roll 3 descends. The hydraulic fluid on the head side of the hydraulic pressure reduction cylinders 4 a and 4 b passes through the logic valves 12 a and 12 b and is discharged to the tuning cylinder 11. The pilot check valve 17 is opened by exciting the solenoid a of the electromagnetic direction switching valve 16, and the working oil of the tuning cylinder 11 is discharged through the oil passage 15, so that the rolling roll 3 is rapidly opened. To do. A predetermined open amount is detected by position sensors 5a and 5b provided in the hydraulic pressure reduction cylinders 4a and 4b, and the electromagnetic directional switching valve 10 is de-energized (returned to the neutral position), thereby stopping the rolling roll 3.
[0011]
In addition, the position control of the rolling roll is not limited to the hydraulic pressure reduction device using the above-described tuning cylinder, but a method using a servo valve is widely adopted (Japanese Patent No. 2820887 and the like). Since it is generally known and the object of application of the present invention is a hydraulic pressure reducing device using a synchronized hydraulic pressure supply device such as a synchronized cylinder, the description thereof is omitted here.
[0012]
[Problems to be solved by the invention]
The hydraulic rolling device using the conventional tuning cylinder described above exhibits its function in that the rolling rolls that move up and down are always horizontal. The horizontal state can be adjusted only when the rolling roll is fully opened, that is, when the pair of hydraulic reduction cylinders are both moved to the stroke end.
In reality, roll roll inclination (deviation of both end positions) that occurred during rolling (during pressure control) and roll inclination due to non-uniform distribution of hydraulic oil due to leakage in the hydraulic circuit such as the tuning cylinder and reduction cylinder accumulate. The rolling rolls are in contact with the rolled material in a state of being largely inclined, and the narrowing and meandering of the rolled material thereby cause a reduction in production capacity. Further, it is possible to adjust the level by making the rolling roll fully open (stroke end of the hydraulic pressure reduction cylinder) at each joining point, but it is extremely disadvantageous in terms of production efficiency for a continuous line.
[0013]
On the other hand, when a servo valve is used, it is possible to control the position so as to eliminate the deviation between both ends of the roll when the rolling roll is closed. However, the opening and closing speed of the rolling roll when passing through the joining point in a continuous line is an element that cannot be ignored when considering the product yield and production capacity. Servo system is required, leading to an increase in construction cost. In general, the management level of hydraulic oil in the servo system is strict, and the maintenance cost increases.
[0014]
The present invention has been made to solve the above-described problems. In a hydraulic reduction device for a rolling mill using a synchronized hydraulic pressure supply device such as a synchronized cylinder, the positional deviation between both ends of the roll during the rolling roll closing operation is calculated. A rolling mill hydraulic pressure reduction method and hydraulic pressure reduction that can be eliminated by a relatively simple and inexpensive configuration, can prevent narrowing and meandering that occur during contact with the rolled material, and can improve production capacity. An object is to provide an apparatus.
[0015]
[Means for Solving the Problems]
Claim 1 of the present invention provides a tuned hydraulic pressure supply device (a tuned cylinder or a pair of flow rate adjusting valves, etc.) to a pair of hydraulic pressure reduction mechanisms (such as a hydraulic pressure reduction cylinder) provided at both end support portions (roll chock) of a roll of a rolling mill. In the hydraulic pressure reduction method of the rolling mill in which the rolls are closed in a horizontal state by supplying equal amounts of hydraulic oil through the rolls, the positional deviation amount of the both end support portions of the roll during the roll closing operation is detected. A hydraulic reduction method for a rolling mill, characterized in that a correction hydraulic oil that eliminates a positional deviation amount is supplied to a hydraulic reduction mechanism. For example, when the lower rolling roll that moves up and down is closed (when it is raised), the position deviation amount of the roll end support is always detected by the position sensor provided in the hydraulic pressure reduction mechanism, and the oil amount corresponding to this deviation is hydraulically reduced. This is supplied to the mechanism to eliminate the positional deviation amount of the roll both ends support part during the roll closing operation.
[0016]
According to a second aspect of the present invention, a pair of hydraulic pressure reduction mechanisms (such as a hydraulic pressure reduction cylinder) provided at both end support portions (roll chock) of a roll of a rolling mill, and a tuned hydraulic pressure supply device (tuned cylinder) are connected to the pair of hydraulic pressure reduction mechanisms. Alternatively, in a hydraulic reduction device of a rolling mill having a hydraulic circuit that supplies an equal amount of hydraulic oil via a pair of flow rate adjusting valves, etc., the positional deviation amount of both end support portions of the roll during the roll closing operation is detected. A hydraulic pressure reduction device for a rolling mill is provided with a correction hydraulic circuit capable of supplying hydraulic oil for eliminating the positional deviation amount to a hydraulic pressure reduction mechanism. The hydraulic circuit of the hydraulic reduction device is composed of a position control hydraulic circuit that has a tuned hydraulic pressure supply device and performs position control (roll parallelism control) at the time of roll closing operation, and a pressure control hydraulic circuit that performs pressure control at the time of rolling. A correction hydraulic circuit is added to such a hydraulic circuit.
[0017]
According to a third aspect of the present invention, a pair of hydraulic pressure reduction mechanisms provided at both end support portions of a roll of a rolling mill and an equal amount of hydraulic oil are supplied to the pair of hydraulic pressure reduction mechanisms via a synchronized hydraulic pressure supply device. In a hydraulic reduction device of a rolling mill having a hydraulic circuit, a correction hydraulic circuit is provided that can supply hydraulic oil to a hydraulic reduction mechanism that eliminates the positional deviation amount of both end support portions of the roll during the roll closing operation. The pair of oil passages can be supplied to the pair of hydraulic reduction mechanisms from the hydraulic source, and the pair of oil passages are selected and the oil amount is adjusted based on the positional deviation amount of the pair of hydraulic reduction mechanisms. A hydraulic reduction device for a rolling mill, characterized by having a control valve. For example, a proportional electromagnetic directional flow control valve is used as the control valve, and an amount of oil necessary for correction is supplied to one of the pair of hydraulic pressure reduction mechanisms based on the positional deviation amount of the pair of hydraulic pressure reduction mechanisms. Eliminates the positional deviation of both ends support.
[0018]
The correction hydraulic circuit is preferably provided with a pressure reducing valve on the hydraulic pressure source side of the control valve, and the pressure of the correction hydraulic circuit is preferably the same as the circuit pressure on the tuning hydraulic pressure supply device side. Further, it is preferable to provide an accumulator on the hydraulic pressure source side of the control valve to improve the response of the correction hydraulic circuit. Furthermore, a shutoff valve is provided on the rolling mill side of the control valve. When the roll closing operation is completed, the shutoff valve is closed to disconnect the correction hydraulic circuit from the position control hydraulic circuit and the pressure control hydraulic circuit, thereby controlling the pressure during rolling. And roll opening operation.
[0019]
In the configuration of the present invention as described above, the position deviation at both ends of the roll is always corrected by the correction hydraulic circuit during the roll closing operation by the tuning cylinder or the like, and the position deviation at both ends of the roll is eliminated. In parallel. As a result, even in a hydraulic reduction device using a tuning cylinder or the like, it is possible to prevent a piece contact (non-uniform reduction) that has occurred when the rolled material is caught, and to prevent narrowing and meandering of the rolled material.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on an embodiment shown in the drawings. 1 and 2 show an example of a hydraulic pressure reducing device for carrying out the hydraulic pressure reducing method for a rolling mill according to the present invention. FIG. 1 shows a case where a tuning cylinder is used as a tuning hydraulic pressure supply device. Reference numeral 2 denotes a case where a pair of flow rate adjusting valves are used in the synchronized hydraulic pressure supply device. In FIG. 1 and FIG. 2, the same parts as those in FIG.
[0021]
In FIG. 1, a rolling mill 1 has a pair of upper and lower rolling rolls 2, 3, and hydraulic rolling cylinders 4 a, respectively, below roll chocks on both the driving side (DS) and working side (WS) of the lower rolling roll 3. 4b is incorporated. The hydraulic pressure reduction cylinders 4a and 4b are provided with position sensors 5a and 5b for detecting the raising / lowering position of the lower rolling roll 3, respectively. Hydraulic circuit A connected pair of hydraulic pressure cylinders 4a, and 4b, as in the prior art, the position control hydraulic circuit A ₁ performing role closing operation time of the position control (the roll parallelism control), pressure control during rolling and a pressure control hydraulic circuit a ₂ which performs. In the present invention, a correction hydraulic circuit B that can supply hydraulic fluid for correction is added to such a conventional hydraulic circuit A.
[0022]
Position control hydraulic circuit A ₁ is the same as the conventional configuration, a pair of hydraulic pressure cylinders 4a, the oil passage 13 4b head side (the piston lower chamber) are connected respectively to the rod side (piston upper chamber) and oil An electromagnetic direction switching valve (three-position switching valve) 10 is provided in the path 14, and a tuning cylinder 11 and a pair of logic valves 12 a and 12 b are provided in the pair of oil paths 13 a and 13 b, and are connected to the oil path 13. A pilot operation check valve 17 that is opened by an electromagnetic directional switching valve (two-position switching valve) 16 is provided in the oil passage 15 for rapid opening operation of the roll.
[0023]
The pressure control hydraulic circuit A _{2 is} also the same as the conventional configuration, and a proportional electromagnetic relief pressure reducing valve 21 and an electromagnetic shut-off valve 22 are provided in the oil passage 20 from the hydraulic pressure source. The branched oil passages 20a and 20b of the oil passage 20 are joined to the oil passages 13a and 13b, respectively, and the proportional electromagnetic relief pressure reducing valve 21 is controlled by a pressure converter 23 provided in the oil passage 20b. The type shut-off valve 22 is operated by a pressure switch 24 provided in the oil passage 13b.
[0024]
The correction hydraulic circuit B is provided with a proportional electromagnetic directional flow control valve (three-position switching valve) 31 in the middle of the oil passages 30a and 30b connected to the oil passages 20a and 20b, and on the rolling mill side of the oil passages 30a and 30b. Electromagnetic shut-off valves 32a and 32b are provided, respectively, and a pressure reducing valve 33 and an accumulator 34 are provided on the hydraulic pressure source side of the oil passage 30b. Incidentally, the oil passage 30b is connected to the hydraulic source of the pressure control hydraulic circuit A ₂ (oil passage 20), and to take advantage of the hydraulic pressure source of the pressure control hydraulic circuit A _2.
[0025]
When the lower rolling roll 3 is raised, the proportional electromagnetic directional flow control valve 31 is based on the positional deviation between the driving side and the working side of the rolling roll 3 and the distribution direction of hydraulic fluid for correction (hydraulic pressure reduction cylinder 4a or 4b). And the amount of hydraulic fluid for correction is controlled by the control panel 35. Detection signals from the position sensors 5a and 5b are input to the control panel 35, the position deviations at both ends of the rolling roll 3 are calculated, and when there is a position deviation, a signal for correcting the deviation is a proportional electromagnetic directional flow rate. It is output to the solenoid of the control valve 31. For example, if the position of the hydraulic pressure reduction cylinder 4a is high, the hydraulic oil is supplied to the hydraulic pressure reduction cylinder 4b and the valve is switched in the direction of discharging the hydraulic oil of the hydraulic pressure reduction cylinder 4a. Are adjusted so that the driving side and working level of the rolling roll 3 are matched.
[0026]
The pressure reducing valve 33 is provided to make the pressure of the correction hydraulic circuit B the same as the hydraulic circuit pressure on the tuning cylinder side. The accumulator 34 is provided to improve the response of the correction hydraulic circuit B.
[0027]
(1) Rolling roll opening operation (down)
As in the prior art, when the welding point J between the preceding material P ₁ and the subsequent material P ₂ approaches the rolling mill 1, the solenoid b of the electromagnetic directional control valve 10 is excited, so that the hydraulic oil is hydraulically supplied by the oil passage 14. Supplied to the rod side of the reduction cylinders 4a and 4b, the lower rolling roll 3 descends. The hydraulic fluid on the head side of the hydraulic pressure reduction cylinders 4 a and 4 b passes through the logic valves 12 a and 12 b and is discharged to the tuning cylinder 11. The pilot operation check valve 17 is opened by exciting the electromagnetic direction switching valve 16, and the working oil in the tuning cylinder 11 is discharged through the oil passage 15, whereby the rolling roll 3 is rapidly opened. A predetermined open amount is detected by position sensors 5a and 5b provided in the hydraulic pressure reduction cylinders 4a and 4b, and the electromagnetic directional switching valve 10 is de-energized (returned to the neutral position), thereby stopping the rolling roll 3. In the present embodiment, for example, the plate passing speed when passing through the welding point is 100 mpm, the rolling roll opening is 20 mm, and the rapid opening speed is 40 mm / second.
[0028]
(2) Rolling roll closing operation (rise)
As in the prior art, when the welding point J of the preceding material P ₁ and the subsequent material P ₂ passes through the rolling mill 1, the hydraulic oil is synchronized by the oil passage 13 by exciting the solenoid a of the electromagnetic direction switching valve 10. It is supplied to the cylinder 11. The oil amounts of the two systems discharged from the tuning cylinder 11 are equal, and this equal amount of hydraulic oil is supplied to the head side of the hydraulic pressure reduction cylinders 4a and 4b through the logic valves 12a and 12b. To rise.
[0029]
(3) Correction at the time of closing operation (up) of the rolling roll When the lower rolling roll 3 is raised, the drive side level and the working side level of the rolling roll 3 are measured by the position sensors 5a and 5b, and the control panel. In 35, the position deviation of both ends of the rolling roll 3 is calculated. If there is a deviation, a signal for correcting the deviation is output from the control panel 35 to the proportional electromagnetic directional flow control valve 31, and the oil amount and distribution direction necessary for correction are set. At this time, since the electromagnetic shut-off valves 32a and 32b are opened by the excitation of the solenoid a, hydraulic oil necessary for correction is supplied to the head side of the predetermined hydraulic pressure reduction cylinder 4a or 4b through the oil passage 30a or 30b. The The above-described deviation calculation and correction operation are always executed while the roll is raised by feedback control. In this embodiment, the roll rising speed is 10 mm / second, the correction oil amount is 5% of the supply amount by the tuning cylinder 11, and the pressure of the correction hydraulic circuit B is made the same as the hydraulic circuit pressure on the tuning cylinder side by the pressure reducing valve 33. Set.
[0030]
(4) When the rolling roll 3 and the rolling material P under the pressure control of the rolling roll come into contact with each other, the circuit pressure rises, so that the pressure switch 24 operates. This signal, the logic valve 12a, 12b to block the position control hydraulic circuit A ₁ closes the electromagnetic shutoff valves 32a, 32b are closed by the unexcited blocking the correction hydraulic circuit B, the pressure control hydraulic circuit A ₂ By opening the electromagnetic shut-off valve 22 by excitation of the solenoid a, the control is switched to pressure control. In this pressure control, the electromagnetic relief pressure reducing valve 21 is controlled by a pressure signal from the pressure transducer 23.
[0031]
Next, in FIG. 2, a pair of flow rate adjusting valves are used instead of the tuning cylinders, and pressure compensated flow rate adjusting valves 18a and 18b with check valves are provided in the pair of oil passages 13a and 13b, respectively. If the throttle amounts of the variable throttles of the flow rate adjusting valves 18a and 18b are set, the flow rate is automatically adjusted by the pressure compensation mechanism, and an equal amount of oil amount can be supplied to the hydraulic pressure reduction cylinders 4a and 4b, respectively. it can. The control accuracy is equal to or less than that of the tuning cylinder (generally, 5% of the maximum flow rate is within the error range). The other hydraulic circuit configuration is the same as that of FIG. 1, operates in the same manner as in FIG. 1, and the same effects as in FIG.
[0032]
In the above embodiment, the case where the tuning cylinder and the flow rate adjusting valve are used in the tuning hydraulic pressure supply device is illustrated. However, the present invention is not limited to this, and it goes without saying that another tuning hydraulic system can be used. Moreover, although the rolling mill demonstrated the two-stage rolling mill with a pair of upper and lower rolling rolls, it cannot be overemphasized that this invention is applicable not only to this but a 4-high rolling mill.
[0033]
【The invention's effect】
Since this invention consists of the above structures, there exist the following effects.
[0034]
(1) Providing a correction hydraulic circuit that can eliminate the positional deviation between both ends of the roll in the hydraulic reduction device of the rolling mill that opens and closes the roll via a synchronized cylinder, etc. It is possible to prevent narrowing and meandering of the rolled material to be performed, and stable operation is possible. In particular, in a continuous line, it is not necessary to reduce the line speed when passing through the welding point more than necessary, and the production capacity can be improved.
[0035]
(2) Since a simple hydraulic reduction device such as a synchronized cylinder can be eliminated by simply providing a relatively simple and inexpensive correction hydraulic circuit, a hydraulic reduction device using a servo valve for obtaining the same effect is provided. Compared to the construction, construction costs and maintenance costs can be significantly reduced.
[Brief description of the drawings]
FIG. 1 is a hydraulic circuit diagram showing one embodiment (tuned cylinder system) of a hydraulic reduction device for carrying out a hydraulic reduction method for a rolling mill according to the present invention.
FIG. 2 is a hydraulic circuit diagram showing one embodiment (flow rate adjusting valve system) of a hydraulic pressure reducing device for carrying out the hydraulic pressure reducing method of the rolling mill of the present invention.
FIG. 3 is a hydraulic circuit diagram showing a conventional hydraulic reduction device.
[Explanation of symbols]
A ₁ ... Position control hydraulic circuit A ₂ ... Pressure control hydraulic circuit B ... Correction hydraulic circuit 1 ... Rolling mill 2 ... Upper rolling roll 3 ... Lower rolling roll 4a ... Hydraulic reduction cylinder (drive side)
4b ... Hydraulic pressure reduction cylinder (working side)
5a: Position sensor (drive side)
5b Position sensor (working side)
10 ... Electromagnetic direction switching valve 11 ... Tuning cylinder 12a ... Logic valve (drive side)
12b ... Logic valve (working side)
13 ... Oil passage 14 ... Oil passage 15 ... Oil passage 16 for rapid opening operation of the roll ... Electromagnetic direction switching valve 17 ... Pilot operated check valve 18a ... Flow rate adjusting valve (drive side)
18b ... Flow control valve (working side)
20 ... Oil passage 21 ... Proportional electromagnetic relief pressure reducing valve 22 ... Electromagnetic shut-off valve 23 ... Pressure transducer 24 ... Pressure switch 30a ... Oil passage (drive side)
30b ... Oil passage (working side)
31 ... Proportional electromagnetic directional flow control valve 32a ... Electromagnetic shut-off valve (drive side)
32b ... Electromagnetic shut-off valve (working side)
33 …… Pressure reducing valve 34 …… Accumulator 35 …… Control panel

Claims (3)

Hydraulic rolling down of the rolling mill that closes the roll in a horizontal state by supplying an equal amount of hydraulic oil to each of the pair of hydraulic rolling down mechanisms provided at both ends of the roll support of the rolling mill via a synchronized hydraulic pressure supply device. In the method
A method of reducing a hydraulic pressure of a rolling mill, comprising detecting a positional deviation amount of both end support portions of the roll during a roll closing operation and supplying a correction hydraulic oil that eliminates the positional deviation amount to a hydraulic reduction mechanism. Hydraulic pressure of a rolling mill having a pair of hydraulic pressure reduction mechanisms provided at both end support portions of a roll of the rolling mill, and a hydraulic circuit for supplying an equal amount of hydraulic oil to each of the pair of hydraulic pressure reduction mechanisms via a synchronized hydraulic pressure supply device In the reduction device,
The hydraulic pressure of the rolling mill is provided with a correction hydraulic circuit capable of detecting the positional deviation amount of the both end support portions of the roll at the time of the roll closing operation and supplying hydraulic oil for eliminating the positional deviation amount to the hydraulic reduction mechanism. Reduction device. Hydraulic pressure of a rolling mill having a pair of hydraulic pressure reduction mechanisms provided at both end support portions of a roll of the rolling mill, and a hydraulic circuit for supplying an equal amount of hydraulic oil to each of the pair of hydraulic pressure reduction mechanisms via a synchronized hydraulic pressure supply device In the reduction device,
A correction hydraulic circuit is provided that can supply hydraulic oil to the hydraulic pressure reduction mechanism that eliminates the positional deviation amount of the both-end support portions of the roll during the roll closing operation. The correction hydraulic circuit is supplied from the hydraulic source to the pair of hydraulic pressure reduction mechanisms. A rolling mill characterized by having a control valve for selecting the pair of oil passages and adjusting the oil amount based on the positional deviation amount of the pair of hydraulic reduction mechanisms in the pair of oil passages capable of supplying Hydraulic reduction device.

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