JPS6238709A - Abnormality diagnosing device for hydraulic rolling down device of rolling mill - Google Patents

Abstract

PURPOSE:To improve the operating rate of a rolling mill and to improve the yield of a rolled product by combining the constant diagnosis during tthe operation of a rolling installation such as prior to start of or during rolling and the periodic diagnosis in the stop state of rolling. CONSTITUTION:A servocontrol valve 13 is driven by the output from a servocontrol amplifier 12 to feed oil to a rolling down jack 14 and discharge the oil therefrom, by which the gap between work rolls is increased or decreased. The displacement of the jack 14 is detected by a draft position detector 15 and the valve 13 is driven through amplifiers 11, 12 until the deviation value DELTAS1 between the detected value S1 and target value S0 of the draft position is made zero. An abnormality diagnosis device 30 is provided and in the constant diagnosis, a device 34 discriminates the presence or absence of the abnormality of a rolling down device from the magnitude of the integrated value M of the draft position deviation DELTAS of an integrator 32. A reference wave signal suitable for the diagnosis is inputted from a generator 31 and the dynamic characteristic of the rolling down device by said input and the reference dynamic characteristic are compared, then whether the difference is within a permissible value or not is discriminated. All the results of the discrimination are displayed on a device 35.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a device for diagnosing abnormalities in a so-called rolling mill hydraulic rolling device that operates a rolling mill rolling mechanism using hydraulic pressure.

[Background of the invention]

Conventionally, rolling operations on a rolling mill equipped with a hydraulic reduction device were carried out by operators or maintenance personnel who read various values such as the voltage at various points in the control panel for the hydraulic reduction device, and made independent judgments based on their experience to control each part. The method used was to make adjustments and ensure that the rolling operation was possible before starting the rolling operation. However, with this method, the changes in the characteristics of the hydraulic pressure reduction device can only be grasped qualitatively, and quantitative maintenance management is not possible.゛Examples of the various elements that make up a hydraulic rolling down device In both U and I, if the accuracy of the plate thickness of the rolled product decreases, the performance and characteristics of the servo valve, which is the flow control valve, will be affected. ″′&(t:&ff1liL・“0ゝ1′-1”e
In addition to understanding the L value, it is also necessary to diagnose the presence or absence of abnormalities.
This is also important for improving the quality of
As shown in Publication No. 3227, the pressure, flow rate, wear particle concentration, displacement of operating members, etc. of hydraulic oil are detected, and the relationship between these detected values is compared with preset reference values and tolerance deviations to detect abnormalities. There are known methods for diagnosing the presence or absence of.

This method automatically estimates the state of mechanical damage due to wear, deterioration, wear, etc. inside the hydraulic equipment and diagnoses the presence or absence of abnormalities, making it possible to predict failures before the hydraulic equipment stops functioning. However, it is not suitable for abnormality diagnosis to understand changes in the characteristics and performance of servo valves, etc., in order to improve the yield of rolled products such as in the hydraulic reduction device of a rolling mill.

[Purpose of the invention]

An object of the present invention is to provide an abnormality diagnosis device for a hydraulic reduction device of a rolling mill that improves the operating rate of a hydraulic reduction rolling mill and improves the yield of rolled products.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention provides constant diagnosis that is performed while the rolling equipment is in operation, such as before the start of rolling or during rolling, while the equipment is kept in its normal motion, and when the hydraulic rolling device is operated while rolling is stopped. It is characterized by having a periodic diagnosis by inputting a reference wave signal, causing the hydraulic pressure lowering device to move in accordance with the reference wave signal, and comparing its dynamic characteristics with a predetermined reference dynamic characteristic. This is done by continuously diagnosing a rolled product while it is being rolled, without making any special movements to diagnose abnormalities, while maintaining normal rolling movements, and during periodic inspections of the entire equipment. The aim is to continuously perform more detailed and reliable diagnosis by inputting a reference wave signal suitable for diagnosis in a state where there is no problem in making movements different from those during rolling.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 7 is a schematic diagram of a hydraulic rolling down device configured in a barrel to which the abnormality diagnosis device according to the present invention is applied, and shows one stand of a rolling mill. In some rolling equipment, a plurality of these rolling mill stands (for example, six stands) may be arranged in tandem.

A rolling mill hydraulic rolling device generally includes two systems for one stand of a rolling mill: an operation side and a drive side.

For example, taking the operating side as an example, a pair of work rolls 2a and 2b that directly roll the material 1 to be rolled, and an intermediate roll 3
a and 3b, reinforcing rolls 4a and 4b.

A reduction jack 14 consisting of a reduction ram 14a and a reduction cylinder 14b, a servo valve 13 for controlling the amount of oil sent to the reduction jack 14. Servo amplifier 12 for driving servo valve 13. An amplifier 11 for adjusting the forward gain of the closed loop position servo system, a lowering position detector 15 for detecting the displacement of the lowering jack 14, and an electric numerical signal indicating the displacement of the lowering jack 14 detected by the lowering position detector 15. Press down position receiver 16 for outputting as
It consists of etc. 6 is an oil tank, 7 is a hydraulic pump, 5
is a hydraulic power unit equipped with these hydraulic devices. Further, three systems of piping are connected to the servo valve 13. That is, a first pipe to which high-pressure oil is supplied from the hydraulic pump 7, a second pipe to send high-pressure oil to the reduction jack 14 and vice versa, and an oil drainage passage from the reduction jack 14 to the oil tank 6. A total of three lines of piping, including the third piping, are connected to the servo valve 13.

Next, the operation of the hydraulic pressure lowering device constructed as described above will be explained.

When the target value So of the reduction position is given, a deviation value ΔS1 occurs between the displacement of the reduction jack 14 (hereinafter referred to as detection value of the reduction position) S output from the reduction position receiver 16, and this Δ
S1 is multiplied by the forward gain of the amplifier 11, and the servo amplifier 12 amplifies the electrical power to enough electrical power to drive the servo valve 13, thereby driving the servo valve 13. Here, the servo valve 13 may be, for example, a direct acting hydraulic servo valve as shown in FIG. This servo valve moves a spool 43 in the axial direction (horizontal direction in the drawing) by a force motor composed of a magnet 41 and a moving coil 42.
The amount of displacement of the spool 43 is determined by the value of the current flowing through the moving coil 42. The amount of displacement of the spool 43 is detected by the detector 45, and can be used for servo valve abnormality diagnosis, which will be described later. Piping from a hydraulic pump is connected to port P8, and piping to an oil tank is connected to port Pa. Further, ports PC1 and Pcz are coupled by piping and connected to a pressure jack. If a positive current is now applied to the moving coil 42 and the spool 43 moves to the right in the drawing, a path for oil to flow will be formed between the ports Ps and Pet, and the high pressure oil sent from the hydraulic pump will be reduced. Flows towards Jajatsuki. Conversely, when a negative current is applied to the moving coil 42, the spool 43 moves in the opposite direction to the left, forming a path for oil to flow between ports Pct and P4, and the oil flows under the pressure on the reduction jack side. This causes the oil to flow from the reduction jack to the oil tank, which has a pressure close to atmospheric pressure. In the servo valve, by increasing the amount of overlap between the sleeve 44 and the spool 43, oil can be prevented from flowing in either direction when no current is flowing through the moving coil (i.e., zero current). However, when looking at the relationship between the current i passed through the moving coil and the resulting valve opening A, there is a dead band as shown by the dotted line in FIG. When constructing a closed-loop position servo system with high response and reverse response to produce rolled products with a high yield, the presence of deadband elements in the system will be an impediment to these objectives, so we will try our best to develop the system shown in Figure 3. The valve is required to open in response to the characteristic shown by the solid line, that is, the current, and is manufactured so that the edge of the sleeve 44 and the edge of the spool 43 are slightly close to each other. In addition, it is difficult in practice to continuously maintain the state shown by the solid line in Figure 3.
It is often used as shown in the solid line or dotted line in the figure.

Returning again to FIG. 7, the explanation of the operation of the hydraulic pressure lowering device will be continued. When the servo valve 13 is driven by the output of the servo amplifier 12 and oil is sent to the reduction jack 14, the reduction ram 14a is pushed up and the reinforcing roll 4b is pushed up.
- The work roll 2b is pushed up through the intermediate roll 3b, and the gap with the upper work roll 2a is reduced. When the servo valve 13 is driven in the opposite direction, the oil in the reduction jack 14 flows in the direction to be discharged, the reduction ram 14a is lowered, and the upper work roll 2a and the lower non-work roll 2 are moved in the opposite direction.
The gap with b increases. The displacement of the screw down jack 14 is detected by the screw down position detector 15, and the displacement of the screw down jack 14 is detected by the screw down position detector 15.
is output as a voltage numerical signal. The direction of change in the detected roll position S1 is the direction in which the deviation value ΔS1 decreases, and the amplifier 11 is changed until the deviation value ΔSs becomes zero.
The servo valve 13 is driven through the servo amplifier 12, and the reduction ram 14a is driven. When the reduction ram 14a moves and as a result, the deviation value ΔS1 becomes zero, the servo valve 13
The current flowing through the ram 14a becomes zero, and the movement of the reduction ram 14a stops. As shown in FIG. 5, the closed-loop position servo system converts the deviation value ΔS between the target roll position value So and the detected roll position value S into a servo valve driving current i using the control panel 110. is converted into an oil flow rate Q per unit time by the servo valve 13, and the oil flow rate Q per unit time is converted into displacement by the reduction jack 14.
The displacement is detected and fed back at the detection 11160 to form a closed loop. The feature is that the deviation value ΔS is controlled to be zero. In the case of a rolling mill hydraulic reduction device, the thickness of the material to be rolled is controlled in microns. On the other hand, if we consider an example of a speed control system for reference, as shown in Figure 6, the difference C between the speed command No. and the speed feedback value N
The electric motor 51 is multiplied by the gain G of the forward gain element 50.
A rotation speed command is output, and the rotation speed is detected by the tacho generator 52 and fed back to form a closed loop. In this case, the difference from a closed loop position servo system is that the differential expansion is a very small value that theoretically cannot be completely zero.

FIG. 1 is a block diagram showing an embodiment of an abnormality diagnosis device for a rolling mill hydraulic rolling device according to the present invention.

In FIG. 1, 30 is an abnormality diagnosis device, 31 is a reference wave signal generator, and 32 is an integrator.

33 is a command circuit that instructs the integrator to start and end integration, hold and reset the integral value, etc. 34 is a determination device that determines the presence or absence of an abnormality, and 35 is a circuit for notifying the operator of the determination result. It is a display device. Abnormality diagnosis is carried out before the start of rolling or during rolling equipment operation, without making the hydraulic rolling device perform any movement that is particularly different from that during rolling operation, and by using a reference wave signal suitable for one diagnosis. This can be broadly divided into periodic diagnosis, which is performed by inputting the information and observing its dynamic characteristics.

Continuous diagnosis is performed while the hydraulic rolling device is in motion for rolling operation, so the abnormality diagnosis device does not actively influence the hydraulic rolling device by inputting a reference wave signal, etc. Diagnosis is performed by capturing signals during normal operation operations.

As mentioned above, the closed-loop position servo system is controlled so that the deviation between the position target value and the detected position value is zero, but in the rolling mill hydraulic rolling device, which requires high response, each component must also have high response. For example, as mentioned above, servo valves are used in a manner that responds sensitively to the input current. Therefore, when the deviation ΔS is zero and the current input to the servo valve is zero, the servo valve opening is not necessarily completely zero, and the oil flows in either direction (from the oil pump to the reduction jack, or The oil flows in either direction (from the reduction jack to the oil tank), and the reduction jack is displaced. When the reduction jack is displaced, the deviation ΔS becomes a finite value other than zero, and current is applied to the servo valve to displace the reduction jack in a direction that makes the deviation ΔS zero. However, the displacement of the screw down does not return until the deviation ΔS becomes completely zero, but there is a small deviation ΔS, and the displacement of the screw down stops when the servo valve current based on this deviation ΔS flows. do. This means that when a small amount of current is applied to the servo valve and the spool is slightly displaced, there is a state in which oil does not flow into or out of the reduction jack6. The servo valve current (hereinafter referred to as the "Null current"), which is used to create a state in which there is no inflow of oil or outflow of oil from the reduction jack, may change over time due to wear of the spool or sleeve, etc., even if the servo valve is the same. There is. Continuous diagnosis is performed by utilizing the presence of this null current and its change over time.

The operation of constant diagnosis will be explained using FIG. 8 in addition to FIG. 1. The command circuit 33 takes in the lowering position target value So,
(FIG. 8(A)) The state of change (ie, rate of change) is monitored. Then, while the rate of change is not zero, the integral command m directed to the integrator 32 is turned OFF, and when the rate of change becomes zero (see figure (B)), the closed-loop position servo is controlled based on the rate of change just before that. The transient response settling time required when the system operates with the desired performance is estimated, and the integral command m is turned on after the above-mentioned time after the rate of change becomes zero. While the target rolling position value So is changing, the position deviation ΔS becomes a value other than zero due to the change. However, during this time, since the integration command m is OFF, the integrator 32 does not perform integration and holds the previous integration value. If the closed loop position servo system has the expected performance at the time when the target value So of the reduction position stops changing and the integral command m turns ON, there will be some position deviation (Figure (C)). A state is reached where a ull current flows. Here, the integrator 32 starts an integration operation and integrates one position deviation value ΔS (turn (D)).

The output M of the integrator 32 is sent to the lowering position control device.

The six servo valve currents ((E) in the same figure) added to the closed loop after appropriate gain adjustment on the reduction position control device side are the sum of the part based on the position deviation value ΔS and the part based on the integrator output M, The integral value M increases until the position deviation value ΔS becomes zero by further displacing the reduction jack to bring the position deviation value ΔS to zero, and after the position deviation value ΔS becomes zero, this integral value M increases to N. Ensure ull current. There is less wear on the servo valve spool and sleeve, and there is less wear on the servo valve's spool and sleeve.
In a state where there is no need to flow current, the integral value M does not become very large, and does not reach the level at which the determination device @34 determines the presence or absence of an abnormality (temporarily assumed to be the level indicated by the dotted line in the diagram), and the determination device 34 detects an abnormality. It is determined that there is no such thing. However, as the servo valve's spool and sleeve wear progresses, and it becomes necessary to flow a large amount of null current, the integral value M under such conditions becomes a large value, unlike that shown in Fig. 8, and the determination device 3
The determination result of 4 indicates that there is an abnormality. In addition, if the performance of each element in the closed-loop position servo system, including the servo valve, deteriorates, the transient response characteristics of the closed-loop position servo system will change, so the integral command m
is turned ON, the position deviation value ΔS during the transient response is integrated, and the integral value M becomes an abnormal value. When the servo valve is replaced with a new one or mechanically adjusted, the
A judgment circuit 34 that resets the integral value M of the integrator 32 (that is, clears it to zero) via the command circuit 33 measures the time from when this reset is performed until the alarm level is reached, and if this is shorter than a certain value. If there are conditions that cannot be treated with adjustment alone, a message will be displayed on the display [35] to the effect that replacement with a new one is required. Furthermore, in cases such as when the spool of the servo valve is locked or when the reduction position detector is broken, the position deviation value ΔS becomes abnormally large, so the integral value M suddenly and abnormally increases. The amount of change and the rate of change of M are monitored, and if both are larger than predetermined reference values, a message indicating that there is a serious abnormality is displayed on the display device 35, and a signal is also sent to the lowering position control device to notify the same. Measures will be taken to prevent rolling equipment from being damaged and rolled products from becoming defective.

Periodic diagnosis is performed by inputting a reference wave signal suitable for diagnosis from the reference wave signal generator 31. The reference wave signal has a waveform such as the input signal shown in Fig. 9 ((A) in the same figure), and in response to this input, the closed-loop position servo system operates and the reduction cylinder changes ((B) in the same figure). Then, as the movement progresses, ΔS changes as shown in the figure. Dead time t1, rise time t2, settling time ta, and deviation ΔS (same figure (C)
)) and the like ((D) in the same figure) are ascertained and compared with a predetermined reference value to determine whether the difference is less than or equal to an allowable value. If the rise time t2 is longer than the reference value, it is determined that the gain of the system has decreased;
If the settling time ta is shorter than the reference value or the settling time ta is longer than the reference value, it is determined that the system is unstable. If the dead time tl is longer than the reference value, it is determined that the wear of the servo valve, etc. is progressing.The integral value is also used as auxiliary information for these determinations.Diagnosis of 0 or more is used to determine whether there is an abnormality or progress toward an abnormal state. Determine the situation and notify the operator using the display device. If it is determined that there is an abnormality here, the process proceeds to diagnosis of the servo valve itself.

For periodic diagnosis of a single servo valve, for example, input a sine wave signal as the servo valve input current i, take in the spool displacement signal, observe the hysteresis characteristic as shown in Figure 10, and compare it with a predetermined reference characteristic. Determines whether the difference is within the allowable value and displays the result of the 1 judgment on the display device.The content displayed as 0 indicates that there is no abnormality, or that if the servo valve uses a rubber spring, the rubber spring should be replaced with a new one. This may include a display that prompts you to do so. Furthermore, as a periodic diagnosis of the servo valve itself, we also diagnose the pressure gain characteristic, which shows the relationship between the pressure at the servo valve's reduction jack side outlet and the amount of spool displacement, and quantitatively estimate the wear state of the edges of the spool and sleeve. , is displayed on the display device to give an indication of when to replace the spool or sleeve with a new one.

As described above, according to this embodiment, serious accidents caused by abnormalities in the hydraulic rolling device can be prevented by constant diagnosis, and rolling dynamic characteristics of the hydraulic rolling machine rolling machine can be quantitatively determined by constant diagnosis and periodic diagnosis. Since it can be ascertained, it can be determined whether or not the thickness yield of the rolled product will decrease even if the rolling operation is continued, which is effective in maintaining and improving the thickness yield of the rolled product. In addition, by conducting periodic diagnosis of the servo valve, which is an important component in the hydraulic pressure reduction device,
Parts that make up a servo valve 1 For example, spool, sleeve,
It is possible to predict the lifespan of rubber springs and the like, making it possible to perform so-called preventive maintenance before equipment breaks down.

Quantify the offset value of a closed-loop position servo system without any hassle.
'- [Effects of the Invention] According to the present invention, since it is possible to grasp the rolling process before the start of rolling and during rolling, maintenance and adjustment of each component of the hydraulic rolling device can be carried out in a planned manner, and the rolling of the hydraulic rolling device can be carried out in a planned manner. Since the dynamic characteristics can also be grasped quantitatively, it is possible to maintain and improve the yield regarding the thickness of rolled products. In addition, equipment failures and accidents related to the hydraulic pressure reduction device can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a structural diagram of a servo valve, which is one component in Fig. 1, and Figs. 3 and 4 show the input current of the servo valve and the valve. Characteristic diagram showing the relationship between opening degrees. Figure 5 is a block diagram of the closed loop position servo system. Figure 6 is a block diagram of the closed loop position servo system.
The figure is a speed control system block diagram, Figure 7 is a schematic configuration diagram of a rolling mill hydraulic reduction device to which the diagnostic device of the present invention is applied, and Figure 8
Figures (A) to (E) are time charts showing the operation of constant diagnosis in one embodiment of the present invention, and Figures 9 (A) to (D) are time charts showing the operation of regular diagnosis in one embodiment of the present invention. A characteristic diagram for explaining the operation, FIG. 1o is a characteristic diagram for explaining an example of periodic diagnosis of a single servo valve. DESCRIPTION OF SYMBOLS 1... Rolled material, 11... Amplifier, 12... Servo amplifier, 13... Servo valve, 14... Rolling jack, 15... Rolling down position detector, 3o... Abnormality diagnosis Device, 31... Reference wave signal generator, 32... Integrator,
34... Determination device, 35... Display device, So...
Rolling down position target value, S... Rolling down position detection value, ΔS...
Rolling position deviation, '-Representative Patent Attorney Katsuo Ogawa -1・'High 2nd figure also 3 figure name 4 figure '1 figure 8 figure

Claims (1)

[Claims] 1. In a rolling mill hydraulic rolling device that detects the roll position of the rolling mill and uses it as a feedback signal and the roll position target value to form a closed loop servo system for roll position control, the deviation value between the roll position target value and the roll position detected value is Alternatively, a means for calculating the integral value of the deviation value, a diagnostic means for diagnosing the presence or absence of an abnormal condition in the hydraulic rolling machine of the rolling mill based on the magnitude of the output signal of the calculating means, and an optional means for the hydraulic rolling machine of the rolling mill. Comparison means for inputting a reference wave signal having a magnitude of 1. An abnormality diagnosis device for a hydraulic rolling machine of a rolling mill, characterized in that it comprises periodic diagnostic means including means for changing a target rolling position value by a minute amount as a target rolling position value in order to periodically perform the rolling mill hydraulic rolling device.