JPH0262083B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a hydraulic reduction control device for a rolling mill equipped with a servo valve in a hydraulic reduction system.

[Conventional technology]

Conventionally, servo valves installed in the hydraulic reduction system of rolling mills are used in hot rolling and cold rolling finishing mills and plate mills.
It has been used for AGC control (automatic gauge control).

On the other hand, in recent years, with the development and popularization of new rolling processes to improve yield in hot rolling or thick plate rolling, large capacity valves have rapidly come into use, as described in Japanese Patent Application Laid-Open No. 162513/1983. I'm getting used to it.

The reason for increasing the valve capacity in this way is that while the cylinder size is almost the same as before, the rolling speed must be several times higher than normal. In the AWC system (automatic width control), a servo valve with a hydraulic oil flow rate of several 100 to 1000/min is used.

This large-capacity servo valve is generally a hydraulic amplification type parent-child valve, as shown in FIG. 3, and a cylinder ram 10 built into the cylinder 3 positions a roll chock (not shown).

In each of the slave valve 1 and the master valve 2, the spool 11 within the valve is normally set near the zero wrap because of the need to improve control performance by minimizing the dead zone during spool operation.

However, in this way, spool 1 is in the zero lap state.
1, there is almost no wrap allowance due to slight movement of the spool during cylinder position control, so that hydraulic oil leaks into the tank as shown in FIG. 4.

Therefore, even if an attempt was made to charge pressure oil (hydraulic oil) from the hydraulic pump to the accumulator, the amount of leakage from the parent valve was large and the required amount of oil could not be charged.

In this way, the required amount of oil cannot be charged, so when the cylinder is moved at high speed when changing the rolling reduction, it may not be possible to move it within the specified time, and there is a risk that the operating rate of the rolling mill will decrease significantly. be. The extra time required for the movement is approximately 20-30% of the specified time.

In order to eliminate such excess time, it is necessary to increase the pump capacity by 20 to 30%.

As mentioned above, leakage loss of hydraulic oil has been a major problem.

Particularly in large-capacity servo valves, the leakage ratio of the master valve 2 to the pilot valve reaches about 5 to 10 times, and it is strongly desired to reduce the leak loss from the master valve 2.

[Problem to be solved by the invention]

In view of these problems in the prior art, the present invention aims to significantly improve the leakage loss of large capacity servo valves without impairing the control performance of the servo valve, and to make each unit of a hydraulic power source compact and economical. The purpose is to design.

[Means to solve the problem]

The present invention provides a rolling mill equipped with a cylinder for rolling down a roll, a parent-child type directional flow control valve between the cylinder and a hydraulic pressure source, and an accumulator for storing pressure oil for moving the cylinder at high speed. In the hydraulic pressure reduction system, a shutoff valve for the parent valve is provided in the pressure oil line between the parent valve of the parent-child type directional flow control valve and the accumulator.

Note that, if necessary, a bypass line is provided in the cutoff valve, and a pressure reducing valve or a flow rate control valve for supplying pressure oil for fine movement of the spool of the parent valve to the parent valve is provided in the bypass line.

[Effect]

A shutoff valve for the master valve is installed in the pressure oil line between the master valve of the parent-child type directional flow control valve and the accumulator, so when the cylinder is not operating, the shutoff valve is closed.
Pressure oil (hydraulic oil) can be prevented from going to the master valve, eliminating leakage to the master valve tank.

In addition, if there is no leakage of pressure oil from the cutoff valve, a bypass line is provided in the cutoff valve, and a pressure reducing valve or a flow rate control valve for supplying pressure oil for fine movement of the spool of the parent valve is provided in the bypass line. This pressure reducing valve or flow rate control valve allows a very small amount of leakage to flow to the main valve, which is incomparable to the amount of leakage from the main valve, and is suitable for lubrication during slight movement of the spool and for small movement of the lower cylinder. Charging can be done without any problem.

〔Example〕

The present invention will be described below based on embodiments shown in the drawings.

Embodiment 1 FIG. 1 shows an embodiment of the first invention as the simplest example, in which a master valve cutoff valve 4 is added to the hydraulic circuit shown in the conventional example.

In this example, a master valve shutoff valve 4 for opening and closing this supply flow path is arranged in a flow path that supplies high-pressure hydraulic oil from a pump P and an accumulator A to a master valve 2, and this master valve shuts off when it is not in operation. This configuration prevents hydraulic oil from leaking into the tank T by closing the valve 4 and reducing the supply pressure to the master valve 2 to zero.

In actual operation, the main valve shutoff valve 4 is closed during non-rolling.
is closed to stop the supply of hydraulic oil to the main valve 2, the supply pressure is made zero, and the cylinder 3 is pressed and held at the retraction limit by a roll balance cylinder (not shown) installed in the rolling mill. .

Next, prior to the start of rolling, the main valve shutoff valve 4 is opened, and the APC installed in the control system of the cylinder 3
Turn on (Automatic Position Control) and prepare for rolling.

Furthermore, after the roll plate has been bitten, the cylinder 3 is controlled to follow the command value to perform rolling, and after the bottom is removed, the cylinder 3 is returned to the backward limit, and then maintained at the backward limit by the roll balance cylinder in the same manner as above, The control operation of closing the master valve shutoff valve 4 is repeated again.

In this way, the spool 1 is opened and closed by the opening/closing operation of the master valve shutoff valve 4, which supplies hydraulic oil to the master valve 2 only during rolling and stops the supply of hydraulic oil during non-rolling.
By setting the lap allowance of 1 to approximately zero, it is possible to prevent hydraulic oil from leaking into the tank T during non-rolling.

For example, when AWC simulation is attempted in a continuous mill, the required amount of hydraulic oil can be reduced by 20 to 30% compared to conventional control methods.

Embodiment 2 FIGS. 2 and 3 show a second invention, and the one in FIG. 2 is a hydraulic circuit in which a pressure reducing valve 5 is disposed in parallel with the master valve cutoff valve 4 in FIG. 1.

By arranging this pressure reducing valve 5 as a bypass flow path of the hydraulic circuit passing through the main valve cutoff valve 4, even if the main valve cutoff valve 4 is closed during non-rolling, the hydraulic oil can be can be supplied to the cylinder 3 via the master valve 2, so the position of the cylinder ram 10 can be independently controlled.

Furthermore, in the case of FIG. 3, a flow rate control valve 6 is arranged in parallel with the master valve shutoff valve 4, and the master valve shutoff valve 4 is closed during non-rolling as in the case where the pressure reducing valve 5 of FIG. 2 is provided. Also, the configuration is such that the position of the cylinder ram 10 can be controlled by supplying hydraulic oil to the cylinder 3 using the flow rate control valve 6.

According to this second invention, since the pressure reducing valve 5 or the flow rate control valve 6 is arranged as a bypass supply path to the cylinder 3 for the hydraulic oil supply system including the parent valve shutoff valve 4, The position of the cylinder drum 10 can be set arbitrarily at each time.

Furthermore, it goes without saying that the amount of hydraulic oil leaking from the master valve 2 is significantly improved by the pressure reduction by the pressure reducing valve 5 or the flow rate limiting effect by the flow rate control valve 6.

〔Effect of the invention〕

The present invention has the following remarkable effects.

(1) The amount of pressure oil leakage from the parent valve of the parent-child type flow control valve is
When the cylinder is not operating, it can be almost completely eliminated. Therefore, the pump capacity can be reduced by 20% to 30% of the amount of pressure oil (hydraulic oil) that conventionally leaked, and the tank capacity can also be reduced by reducing the pump capacity, so the initial cost of the equipment is reduced.

Furthermore, the capacity of the pump motor of the hydraulic power source can be reduced by 20 to 30%, resulting in a significant power saving effect.

(2) The present invention also provides a bypass line for the shutoff valve, and a pressure reducing valve or a flow rate control valve that can supply a very small amount of pressure oil to the parent valve compared to the amount of leakage from the parent valve. Since the pressure oil leak can be suppressed to a very small amount, the position of the cylinder can be set by fine movement.

(3) Furthermore, if the present invention is implemented in existing equipment, for example, instead of the 10 pumps used, only 7 to 8 pumps will be needed because the leakage of the master valve has disappeared, so 2 to 8 pumps will be needed as spare standby pumps. 3
You can secure a table. Therefore, if a method is adopted in which active pumps and standby pumps are used alternately, the life of the pump will be significantly extended.

[Brief explanation of the drawing]

FIG. 1 shows an outline of a circuit system of a hydraulic pressure reduction device according to the first invention, and FIGS. 2 and 3 show an example in which the circuit system is equipped with a pressure reducing valve and a flow rate control valve according to the second invention, FIG. 4 shows a detailed sectional view of the parent-child type directional flow control valve. 1: Child valve, 2: Main valve, 3: Cylinder, 4: Main valve isolation valve, 5: Pressure reducing valve, 6: Flow control valve, 10: Cylinder ram, 11: Spool, 12: Pressure oil line, 13: Bypass Line, 14: Tank line, A: Accumulator for pressure oil storage, P: Pump, T: Tank.

Claims (1)

[Claims] 1. A cylinder device for compressing a roll, a parent-child type directional flow control valve between the cylinder and a hydraulic pressure source, and an accumulator for storing pressure oil for moving the cylinder at high speed. A hydraulic reduction control device for a rolling mill, characterized in that a parent valve shutoff valve is provided in a pressure oil line between the parent valve of the parent-child type directional flow control valve and the accumulator in the hydraulic reduction system of the rolling mill. . 2. A hydraulic reduction system for a rolling mill, comprising a cylinder for rolling down a roll, a parent-child type directional flow control valve between the cylinder and a hydraulic source, and an accumulator for storing pressure oil for moving the cylinder at high speed. In the parent-child type directional flow control valve, a parent valve shutoff valve is provided in the pressure oil line between the parent valve and the accumulator, a bypass line is provided in the shutoff valve, and a bypass line is provided in the bypass line for fine movement of the spool of the parent valve. A hydraulic pressure reduction control device for a rolling mill, characterized in that it is provided with a pressure reducing valve or a flow control valve for supplying pressure oil to a parent valve.