JPH061412B2 - Mechanical vibration suppressor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for suppressing mechanical vibration of a device driven by a hydraulic cylinder or an electric motor.

[Conventional technology]

The mechanical vibration of various devices is often based on the vibration of the drive system such as the torsion of the drive shaft of the electric motor or the vibration of the hydraulic cylinder. This mechanical vibration will be described by taking the rolling mill of FIG. 5 as an example.

The rolling mill 10 shown in FIG. 5 is a general four-high rolling mill, and includes a pair of work rolls 14 and 14 for rolling the material 12 to be rolled in the housing 11, and a pair of work rolls 14 and 14. A pair of reinforcing rolls 16 and 16 for supporting 14 are provided. A hydraulic cylinder 18 is provided below the rolling mill 10 as a rolling-down device for controlling the roll gap. The hydraulic cylinder 18 is provided with a hydraulic oil pump 24 via a servo valve 22 controlled by a controller 20.
The pressure oil in the oil tank 26 is supplied.

In the rolling mill 10 configured as described above, the work rolls 14 and 14 are rotationally driven by an electric motor via a spindle (not shown) to roll the material 12 to be rolled to a predetermined plate thickness. Then, the roll gap between the work rolls 14 and 14 determines the amount of pressure oil discharged by the pressure oil pump 24 from the control device 2
This is performed by controlling the servo valve 22 with 0.

In the rolling mill, if mechanical vibrations (uneven rotation) of the work rolls 14, 14 occur, the rolling speed is not constant, which affects the delivery side plate thickness of the material 12 to be rolled. Therefore, conventionally, the shaft torque is actually measured, or by means of an observer or the like, for example, the drive-side shaft torque is estimated and calculated, and the fluctuation due to the shaft torque or the delay due to the shaft torque of the roll on the working side is estimated and inverted. Generally, torque is applied to suppress vibration. However, this method is very difficult to put into practical use because it is necessary to deal with the problem of mounting the sensor and the complicated calculation. In particular, when the vibration frequency exceeds 50 Hz, there is a drawback that the calculation speed needs to be increased, a high-performance calculator is required, and the cost also increases.

On the other hand, in the rolling mill shown in FIG. 5, by controlling the servo valve 22 by the control device 20, it is possible to obtain the roll gap, that is, the high-speed response of the rolling control. The reduction response by this hydraulic reduction device is 20 to 3
It is possible to obtain a frequency characteristic of 0 Hz. Further, also in terms of this rolling control, further high-speed responsiveness is required in order to obtain a rolled product of high quality. However,
The natural frequency of the pressure oil piping system in the above rolling mill is generally 50 to 100 Hz, and the longitudinal rigidity frequency of the rolling mill 10 is 40 to 70 Hz. Therefore, as the response of the control system becomes faster, these pressures The natural vibration frequency of the oil piping system and the longitudinal rigidity frequency of the rolling mill are close to each other, and resonance with these frequencies often induces the natural vibration of the mechanical system.

FIG. 6 shows a concrete example of the vibration. In FIG. 6, the upper row shows the deviation of the strip thickness of the rolled material 12, the interruption shows the rolling position (position of the hydraulic cylinder 18), and the lower row shows the waveform of the servo current for controlling the servo valve 22. Then, in order to clarify the state of vibration, I, II
The chart speed is changed in sections III and III.
Section II has 20 times the chart speed of Section I.
III is 5 times the chart speed of section II.

From FIG. 6, the response frequency by the control device resonates with the frequency characteristic of the pressure oil piping system from a certain point in time, and the rolling position also vibrates, which has a great influence on the outlet plate thickness as a product.

On the other hand, Japanese Patent Application Laid-Open No. 58-43195 discloses a method of inserting a notch filter into a control loop as shown in FIG. 7 to prevent the above mechanical vibration due to resonance. That is, the set value is given to the control unit 30 via the addition calculator 28, and the control signal output from the control unit 30 is input to the control target 34 via the notch filter 32. Then, the output of the controlled object is fed back to the feedback element 36.
And the detected value is negatively fed back to the addition calculator 28.

[Problems to be solved by the invention]

However, when the notch filter as described above is inserted in the control loop, the hunting phenomenon due to the transient characteristic tends to occur. That is, when the input signal enters the step as shown in FIG. 8A, the output signal causes a vibration phenomenon as shown in FIG. 8B to cause hunting. As a result,
Inserting a notch filter in the control loop is not always ideal, and in some cases it may be better not to insert the filter if vibrations do not occur.

Further, the vibration frequency changes due to changes in the propagation speed of vibration due to temperature changes, and in the case of a rolling mill, the rolling material, rolling load, rolling speed, coil diameter, etc., and the amplitude also changes. Therefore, in many cases, mechanical vibration cannot be suppressed simply by inserting a notch filter for a specific frequency as in the conventional case.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a mechanical vibration suppressing device capable of suppressing mechanical vibrations of various devices in a favorable manner.

[Means for solving problems]

In order to achieve the above-mentioned object, the mechanical vibration control device according to the present invention feeds back an output of a controlled object and gives a control signal to the controlled object to maintain a predetermined operating state,
In a mechanical vibration suppression device equipped with a variable notch filter that cuts an output signal generated by a control unit, while detecting mechanical vibration of a control target, the frequency of mechanical vibration and the notch frequency of the variable notch filter are tuned. The phase synchronizing means and the gain adjusting means for changing the gain of the variable notch filter in proportion to the magnitude of the amplitude of mechanical vibration are provided, and each of the gain adjusting means and the phase synchronizing means is connected to the variable notch filter. .

[Action]

In the present invention configured as described above, the natural vibration of the controlled object such as a rolling mill, even when it varies depending on the rolling conditions and the surrounding environment, the notch frequency of the variable notch filter is tuned to the natural vibration frequency of the controlled object, Further, by changing the gain of the variable notch filter according to the magnitude of the amplitude of the controlled object, the mechanical vibration of the controlled object can be suppressed well.

〔Example〕

A preferred embodiment of a mechanical vibration suppressing device according to the present invention will be described in detail with reference to the accompanying drawings. The parts corresponding to the parts described in the above-mentioned prior art are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 1 is a block diagram showing an embodiment of a vibration suppressing device according to the present invention.

In FIG. 1, the output of the control unit 30 is input to the control target 34 via the variable notch filter 38. The output gain of the variable notch filter 38 is adjusted by the gain adjuster (gain adjustment circuit) 40, and the notch frequency is controlled by the phase synchronization circuit 42.

The gain adjuster 40 is a known one in which a capacitor and a rectifier are connected in series, and inputs a gain adjustment signal b proportional to the amplitude of the control target to the variable notch filter 38,
The output of the variable notch filter 38 has a magnitude corresponding to the amplitude of mechanical vibration of the controlled object 34. The phase synchronization circuit 42 also has a known circuit configuration,
As shown in FIG. 2, the phase comparator 44 and the low-pass filter 4 are provided.
6. It comprises an amplifier 48 and a voltage controlled oscillator 50.

The variable notch filter 38 has a structure in which an adder / subtractor 52, a multiplier 54, an integrator 56, a multiplier 58, and an integrator 60 are connected in series as shown in FIG. And
The outputs of the integrators 56 and 60 are fed back to the adder / subtractor 52. The output signal a of the phase locked loop is input to the multipliers 54 and 58. Then, the output of the variable notch filter 38 is input to the amplifier 64 via the multiplier 62 to which the output signal b of the gain adjuster 40 is input, and is given to the control target 34.

In the embodiment configured as described above, the natural vibration frequency of the controlled object is fed to the phase comparator 44 of the phase locked loop 42.
Input as input signal v ₁ . The phase comparator 44 compares the phase of the input signal v _{1 with} the phase of the output v ₀ of the voltage controlled oscillator 50, and outputs a difference signal voltage v _d proportional to the difference. This difference signal voltage v _d passes through a low pass filter 46 and an amplifier 48.
After being input to and amplified, it is given to the voltage controlled oscillator 50. The voltage controlled oscillator 50 controls the oscillation frequency so as to approach the input signal frequency, that is, to tune.

In this way, the phase locked loop circuit 42 gives the variable notch filter 38 a frequency f equal to the mechanical natural frequency of the controlled object 34 as shown in FIG.
The notch frequency of 8 is changed.

On the other hand, the gain adjuster 40 detects the amplitude of the mechanical natural vibration of the controlled object 34 as a voltage, outputs an output proportional to the amplitude to the multiplier 62 as shown in FIG. 4B, and outputs the variable notch filter 38. Adjust. That is, controlled object 3
4 has a large vibration amplitude, the variable notch filter 3
8 is increased and the control signal from the control unit 30 is cut. When the vibration amplitude of the controlled object 34 is small,
That is, when not oscillating, the output of the variable notch filter 38 is reduced so that the control signal from the control unit 30 is input to the control target 34 without being cut.

In this way, in this embodiment, the natural vibration can be suppressed even when the mechanical natural vibration frequency of the controlled object is changed by the variable notch filter 38.
Since the control signal is attenuated according to the amplitude of the natural vibration, the natural vibration of the controlled object can be suppressed well.

In addition, in the said Example, although the case where the natural vibration of a rolling mill was suppressed was demonstrated, it is applicable also to the other apparatus driven by an electric motor, a cylinder, etc.

〔The invention's effect〕

As described above, according to the present invention, the variable notch filter is inserted in the control loop, and the notch frequency of the variable notch filter is tuned to the natural vibration frequency of the controlled object via the phase synchronization means, and its output Since the gain is made to be proportional to the vibration amplitude of the controlled object via the gain adjusting means, the transient characteristic of the variable notch filter can be controlled by the gain, and the natural vibration of the controlled object can be effectively suppressed by preventing hunting. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a mechanical vibration suppressing device according to the present invention, FIG. 2 is a block diagram showing an example of a phase locked loop circuit of the embodiment, and FIG. 3 is a block showing an example of a variable notch filter. Fig. 4A is an explanatory diagram of the output signal of the phase locked loop circuit, Fig. 4B is an explanatory diagram of the output signal of the gain adjuster, Fig. 5 is an explanatory diagram of the four-high rolling mill, and Fig. 6 is a reduction control. FIG. 7 is an explanatory diagram showing a resonance example in the system, FIG. 7 is an explanatory diagram of a mechanical vibration suppressing method using a conventional notch filter, and FIG. 8 is an explanatory diagram of an output signal chattering phenomenon in the conventional mechanical vibration suppressing device. 28 ... Addition calculator, 30 ... Control part, 38 ... Variable notch filter, 34 ... Control object, 36 ... Feedback element,
40 ... Gain adjuster, 42 ... Phase synchronization circuit.

Claims (1)

[Claims] 1. A control unit for feeding back an output of a control target to give a control signal to the control target to maintain a predetermined operating state, and a variable notch filter for cutting an output signal generated by the control unit. In mechanical vibration suppression device,
Phase synchronization means for detecting the mechanical vibration of the controlled object and for tuning the frequency of the mechanical vibration and the notch frequency of the variable notch filter, and the variable in proportion to the magnitude of the amplitude of the mechanical vibration. A mechanical vibration suppressing device, comprising: a gain adjusting means for changing a gain of a notch filter, wherein each of the gain adjusting means and the phase synchronizing means is connected to the variable notch filter.