JPS585725B2 - Yuatsu Atsukashiki Tsuenki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic rolling mill, and particularly to a structure for improving the natural frequency of the hydraulic rolling machine load system.

The rolling method in rolling mills has shifted from the conventional electric rolling method using an electric motor to a hydraulic pressure rolling method using mechanical hydraulic servo or electrohydraulic servo valves, and its responsiveness has improved dramatically.

Measures to improve responsiveness in the latter case have been proven to include 1) improving the responsiveness of the electro-hydraulic servo valve, 2) shortening the length of the pipe from the servo valve to the reduction jack, and 3) improving the control device. be.

However, with the promotion of the above measures, we are now approaching the limit.

Therefore, in order to further dramatically improve responsiveness, it has become necessary to study the load system of the rolling device, that is, the rolling mill itself.

A schematic diagram of a conventional hydraulic rolling mill is shown in FIGS. 1 and 2.

The rolling mill has upper and lower work rolls 4 and 5 for rolling the metal strip 12.
, upper and lower reinforcing rolls 2 and 3 for reinforcing them, their bearings 6 to 9, a mill housing 1 for guiding the bearings and receiving rolling force, and rolling for controlling the gap between the upper and lower work rolls 4 and 5. It is composed of a lowering jack formed by a piston 10 and a lowering cylinder 11.

Also provided are a flow control valve 15 and a servo amplifier 16 for controlling the position of the rolling piston 10, a rolling piston displacement gauge 14 for detecting and feeding back the position of the rolling piston, and a rolling force gauge 13 for detecting rolling force.

In Figure 1, a is the position servo system, and b is the BISRA A.
A GC system is shown, and the response of the roll down device is typically expressed in terms of the bandwidth frequency of this position servo system.

Although the response of this rolling device has been dramatically improved by the above-mentioned measures 1) to 3), there is basically a big problem that the response cannot exceed the natural frequency of the rolling device load system.

Even in an actual rolling mill, the response of the rolling device is about 60 to 80% of the rolling device load system.

The natural frequency of this rolling device load system is determined by the natural mill constant of the rolling mill (spring constant specific to the rolling mill when control such as the BISRA AGC system is not performed), the spring constant of the metal strip 12, and numbers 1 to 1 in FIG. It is determined by the equivalent mass calculated from 10.

In order to increase this natural frequency, the conventional method a) increases the natural mill constant of the rolling mill.

b) Countermeasures such as reducing the equivalent mass can be considered, but these countermeasures have little effect for the following reasons.

1) Since each spring system acts in series with the movement of the reduction piston 10, increasing the spring constant of some of them is ineffective and uneconomical.

ii) The Hertzian flatness of the roll, bearings, etc., which are the main causes of a decrease in the spring constant, are almost determined by the rolling conditions, and it is difficult to change the width of these parts.

For the above reasons, in order to dramatically improve the responsiveness of the rolling mill, it was necessary to develop a rolling mill structure based on a completely new idea.

The purpose of the present invention is to eliminate the drawbacks of the conventional structure described above, to improve the natural frequency of the rolling device load system with a simple and economical structure, and to provide a hydraulic system that can perform good plate thickness control using a highly responsive hydraulic rolling device. To provide a rolling mill.

The present invention is characterized in that fluid is sealed in the other oil chamber of the reduction jack so as to have a spring effect against the movement of the reduction piston at least during rolling.

In a conventional rolling mill, there is no backlash between the machine parts, and the amount of elastic deformation thereof is proportional to the force.

That is, FIG. 2 shows a case where all the elastic deformation parts can be replaced with springs.

Here, Kh: Equivalent spring constant Kb1 of the mill housing:
Equivalent spring constant Kb2 including the reinforcing roll bearing under the rolling piston and the lower reinforcing roll neck, etc. Kb2: Equivalent spring constant K including the rolling force counting reinforcing roll bearing and the upper reinforcing roll neck, etc. Spring constant of the oil in the rolling jack, Ke: equivalent spring constant including Hertzian flattening and bending shear deformation between the work roll and reinforcing roll, Kw: equivalent spring constant including Hertzian flattening and bending deformation of the work roll Ks: equivalent spring constant of the metal strip.

Next, a model of these is shown in Fig. 3.

Here, mh: equivalent mass including mill housing and upper reinforcing roll bearing, mBr: equivalent mass of reinforcing roll, mW
r: Equivalent mass including the work roll and its bearing mc: Equivalent mass including the lower piston and one side of the lower reinforcing roll bearing (1/Kx=2/Kw+1/Ks).

Here, the natural mill constant Km can be calculated from the amount of variation in the work roll gap due to normal rolling force.

That is, 1/Km"=1/2Kh+1/2Kb1+1/2Kb2+1/2Ke±2/Kc+Z/Kw.

Further, the spring constant KD of the hydraulic pressure lowering device load system is approximately expressed by .

Here, when the first term on the right side of equation (2) is smaller than the second term, KD becomes approximately equivalent to the natural Mill's constant, excluding the spring effect of the metal band.

In this case, the metal strip is being rolled, and when the work roll is open, that is, when the rolling piston is positioned, KD is defined only by the first term on the right side of equation (2).

In reality, both the first and second terms on the right side must be considered.

The method for improving KD in the present invention is to first improve the first term on the right side of equation (2), and a specific example thereof is shown in FIGS. 4a to 4d.

That is, FIG. 4a is a schematic cross-sectional view of a conventional reduction jack,
b is its equivalent model system.

FIG. 4c is a diagram illustrating a specific method of achieving a spring effect by sealing hydraulic oil at a predetermined pressure into another oil chamber of the reduction jack according to the present invention.

Here, during rolling, the four-way solenoid valve 18 is in a de-energized state, and the hydraulic oil from the pressure oil source 19 is cut off, and the hydraulic oil in the pressure oil sealing chamber 21 is cut off by the pilot check valve 17. There is.

When the reduction piston 10 is moved up and down over a wide range due to roll change, etc., the four-way solenoid valve 18 is energized, the pilot check valve is opened, and the hydraulic oil can freely enter and exit the pressure oil chamber 21, and the flow rate control valve 15 commands. Press down piston 1
0 can be easily driven.

With the simple method described above, it is possible to greatly improve the KD value.

A state in which Ke' is added to the equivalent model d is shown.

In order to achieve the same effect, a structure in which one or more additional cylinders are provided separately from the lowering jack is shown in Figures 5 a to b.
Shown below.

That is, this actual case is essentially the same as filling another oil chamber of the reduction jack with hydraulic oil at a predetermined pressure.

In order to improve KD, the second term on the right side of equation (2), that is, the case where an elastic body is provided between the lower piston or the lower reinforcing roll bearing and the mill housing or the upper reinforcing roll, is
Shown in Figures a-c.

Figure 6a shows a case where an elastic body is arranged between the lower reinforcing roll bearing 7 and the upper reinforcing roll bearing 6 using the ram-piston method.The operations of the pilot tick valve 17, etc. are the same as in the case of Fig. 5. .

A detailed view thereof is shown in FIG. 6b. That is, the movement of the lower reinforcing roll bearing 7 is transmitted to the upper reinforcing roll bearing 6 through the oil chamber 24, ram 23, and anti-vibration rubber 25, and the hydraulic oil in the oil chamber 24 provides a spring effect.

If the vibration isolating rubber 25 is given an initial compressive strain, leakage of hydraulic oil can be sufficiently compensated for.

This method also serves as a so-called upper reinforcing roll balance, and has nothing to do with the natural Mill constant because the upper reinforcing roll bearing 6 and the lower reinforcing roll bearing are not mechanically connected against the movement of being separated in opposite directions. Therefore, this change in the spring constant of the hydraulic oil will not have any adverse effect on the rolling force feedback loop in the BISRA AGC system.

Furthermore, since this anti-vibration rubber has a large internal damping, it also has the effect of reducing the peak value of the gain near the resonance point of the load system of the rolling device by the leaf spring 26 and the fulcrum 7 as shown in FIG. 6c.

A method may be used in which an elastic body is formed and the initial gap between the upper reinforcing roll bearing 6 and the lower reinforcing roll bearing 7 is adjusted by adjusting the upper and lower parts of the metal fitting 28.

FIG. 7 shows an arrangement of a fixing block 29 in the mill housing 1 to achieve the same effect as in FIG.

Incidentally, if an elastic body is disposed between the lower reinforcing roll bearing and the mill housing as shown in FIGS. 8a and 8b, the equivalent spring constant of the hydraulic lowering device load system can be further increased.

By simply increasing the equivalent spring constant and, in turn, the natural frequency of the load system of the rolling device using the method described above, it has become possible to achieve a highly responsive hydraulic rolling device, which was almost impossible with conventional structures.

In conventional hydraulic rolling mills, the response limit of the rolling device was approximately 60 to 80% of the natural frequency of the rolling device load system.

However, according to the present invention, it is possible to easily improve the natural frequency of the rolling device load system, and the response limit can be easily increased to about three times that of the conventional structure.

Note that: 1) In FIGS. 6 a to 6 c, 7 and 8 a to b, the elastic body is shown as hydraulic oil, vibration isolating rubber, or a plate spring, but it may be of any material.

Further, an elastic body may be used to communicate between the upper and lower reinforcing roll bearings or with the mill housing.

2) Although this embodiment has been explained using a four-fold rolling mill, it is also applicable to a double-rolling mill or other multiple rolling mills.

That is, in the case of a double rolling mill, the upper and lower work rolls are eliminated in this example, and in the case of a multiple rolling mill, the largest diameter roll is made to correspond to the reinforcing roll of this example. corresponds to

3) In this example, we have explained the case where the lowering jack is installed at the bottom of the mill housing, but this also applies to i) when the lowering jack is installed at the upper part of the mill housing, ii) when the lowering piston and the lowering cylinder are turned upside down, i.e. It can also be applied to cases where the reduction piston is fixed to the mill housing and the reduction cylinder is driven.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a conventional hydraulic rolling mill viewed from the operation or drive side, Figure 2 is a schematic diagram of Figure 1 viewed from the pass line direction, Figure 3 is an equivalent model diagram, and Figure 4 8 to 8 show schematic structural diagrams illustrating the present invention. Explanation of symbols, 1... Mill housing, 2...
...Top reinforcing roll, 3...Bottom reinforcing roll, 4
...Top work roll, 5...Bottom work roll, 6...Top reinforcing roll bearing, 7...
Lower reinforcement roll bearing, 8... Upper work roll bearing,
9... Lower work roll bearing, 10... Reduction piston, 11... Reduction cylinder, 12...
...Metal strip, 13...Rolling force meter, 14...
...pressure piston displacement meter, 15...flow control valve, 16...servo amplifier.

Claims (1)

[Claims] 1. In a hydraulic reduction rolling mill configured to control the amount of oil in the reduction jack by a flow control valve, at least during rolling, there is a gap between the other oil chamber of the reduction jack and the means for supplying hydraulic oil to this oil chamber. The hydraulic rolling mill is characterized in that an oil passage closing means is disposed for closing the oil passage between the oil chamber and the hydraulic oil supply means and sealing the hydraulic oil in the oil chamber.