JPH04251605A - Method for automatically diagnosing hydraulic pressure control system - Google Patents

Abstract

PURPOSE:To surely diagnose the abnormality of a general hydraulic pressure control system by a simple constitution regardless of during operation or suspension. CONSTITUTION:An actuator 5 and pressure detector 6 are provided in a bent circuit 43 of a reducing valve 42 which is provided on the hydraulic pressure control system 4 which is an object of diagnosis. A prescribed oil pressure is introduced into the bent circuit 43 with the actuator 5 and the fluctuation of pressure that is generated in the bent circuit 43 at this time is detected with the pressure detector 6. Both or one of the magnitude of amplitude of fluctuation in pressure that is detected with the pressure detector 6 and the length of time until the oil pressure is converged to a certain pressure is checked with a diagnostic device 7 and the abnormality of the hydraulic pressure control system 4 is quantitatively diagnosed based on that result. The operator is informed by properly indicating the diagnostic result with the diagnostic device 7 in an indicating part 8.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention allows the state of each part of a hydraulic pressure control system including a pressure reducing valve and a vent circuit thereof to maintain a constant supply pressure to a predetermined delivery destination to be normal (Good), for example.
The present invention relates to an automatic diagnosis method for quantifying into three stages: , Caution, and Damage.

0002

[Prior Art] A rolling force control system that applies a predetermined reduction to a rolled material by the rolling rolls of a rolling mill, and a drawing force that applies a predetermined drawing force to a slab by the pinch rolls of a continuous casting facility. In each process of steelmaking, such as control systems, hydraulic pressure control systems are configured to control the hydraulic pressure supplied to hydraulic cylinders, which are the sources of force, and to perform predetermined work using the force generated by the hydraulic cylinders. In this type of hydraulic pressure control system, a pressure reducing valve equipped with a vent circuit is interposed between the hydraulic cylinder, which is the destination of hydraulic pressure, and the hydraulic source, and the operation of the pressure reducing valve reduces the pressure to the hydraulic cylinder. Many configurations have been adopted in which the feed pressure is stabilized and this feed pressure can be changed as appropriate from the outside by operating the vent circuit.

By the way, in a hydraulic pressure control system, the sealing performance of each part of the system, such as the hydraulic cylinder, the hydraulic piping connected to the hydraulic cylinder, and various control valves disposed midway through the hydraulic piping, changes over time. The problem is that the amount of hydraulic oil leaking increases as the system deteriorates, and in order to prevent malfunctions caused by this, regular maintenance and inspection of each part of the system is essential.

[0004] Generally, this maintenance and inspection work involves measuring the resistance value and neutral point current of the servo valve, measuring the force generated by the hydraulic cylinder under a predetermined supply pressure, and furthermore, This method is implemented by manually measuring the dynamic characteristics of the entire system using a transfer function analyzer and diagnosing system abnormalities from these measurement results, but it has the disadvantage of requiring a large amount of work time. It requires a high level of skill to quantitatively judge not only the presence or absence of an abnormality, but also the degree of abnormality, and in practice, for safety reasons, component equipment must be replaced at a stage when the degree of abnormality is minor, resulting in unnecessary waste. The problem was that there were many.

In order to overcome these difficulties, the following two methods have been proposed as methods for automatically diagnosing abnormalities in hydraulic pressure control systems without manual intervention. The first method, as disclosed in Japanese Unexamined Patent Publication No. 111709/1983, is to apply an appropriate diagnostic signal to the servo section of the hydraulic pressure control system, capture the accompanying response signal of the servo system, and then use the signal to generate the signal. This is a method that attempts to quantitatively determine abnormalities in the hydraulic pressure control system by examining the waveform of As disclosed in Japanese Unexamined Patent Publication No. 172004/1983, this method involves capturing specific signals for a plurality of diagnostic items at specific timings from the control input/output signals of the servo section during its operation, and This is a method for quantitatively diagnosing the quality of the dynamic characteristics of the hydraulic pressure control system or the condition of the components of the hydraulic pressure control system by comparing these with different determination reference values.

[0006]

[Problems to be Solved by the Invention] However, the first method, like the conventional manual diagnosis method, is a method that can be performed only when the line is stopped, and cannot be used to detect abnormalities that occur while the line is in operation. There were some difficulties that could not be addressed. On the other hand, the second method has the advantage that it can be implemented even while the line is in operation; however, when implementing this method, a computation device with a complex configuration is required for the signal processing described above. Therefore, the cost required for implementation is high, and the maintenance of this arithmetic device requires a great deal of effort.

Furthermore, all of these methods can only be implemented in a hydraulic pressure control system equipped with a servo unit for performing complex control, such as a rolling force control system in a rolling mill, and are not applicable to general hydraulic pressure control systems. There was a problem that it was impossible to apply it to a pressure control system.

The present invention has been made in view of the above circumstances, and allows automatic diagnosis of abnormalities in the hydraulic pressure control system to be performed with a simple device configuration, regardless of whether the line is in operation or at rest. Another object of the present invention is to provide an automatic diagnosis method for a hydraulic pressure control system that can be applied to general hydraulic pressure control systems.

[0009]

[Means for Solving the Problems] An automatic diagnosis method for a hydraulic pressure control system according to the present invention is a hydraulic pressure control system equipped with a pressure reducing valve that keeps the supply pressure to a hydraulic pressure destination constant and a vent circuit thereof. In the method of automatically diagnosing abnormalities occurring in each part of the vent circuit, a predetermined hydraulic pressure is introduced into the vent circuit, the fluctuating pressure generated in the vent circuit at this time is detected, and the magnitude of the amplitude of the fluctuating pressure and/or the constant pressure is determined. The method is characterized in that the degree of the abnormality is determined based on the length of time until convergence.

0010

[Operation] In the present invention, a predetermined hydraulic pressure is introduced into the vent circuit of a pressure reducing valve provided in a general hydraulic pressure control system, and the fluctuating pressure generated in the vent circuit is detected, and the amplitude and the constant pressure are detected. The abnormal state is quantitatively diagnosed by examining one or both of the time required for the pressure to converge and comparing these with respective determination reference values. Therefore, regardless of whether the hydraulic pressure control system to be diagnosed is in operation or inactive, changes in the condition of the hydraulic pressure control system over time can be reliably detected without affecting the main circuit. can be grasped. Further, the only equipment necessary to carry out the present invention is an actuator that introduces a predetermined hydraulic pressure into the vent circuit, a pressure detector for the vent circuit, and a simple diagnostic device that performs the diagnosis.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to drawings showing embodiments thereof. FIG. 1 is a schematic block diagram showing an implementation state of an automatic diagnosis method for a hydraulic pressure control system (hereinafter referred to as the "method of the present invention") according to the present invention in a pull-out force control system using pinch rolls of continuous casting equipment.

In the figure, reference numeral 1 denotes a slab, and the slab 1 is continuously pulled out from a mold (not shown) by the rotation of a pair of pinch rolls 2, 2 that are in rolling contact with each other on both sides of the slab. The pinch rolls 2, 2 are pressed against the surface of the slab 1 by hydraulic pressure applied to these supporting positions by separate hydraulic cylinders 3, 3. It is arranged so that a pulling force can be applied.

The operating oil pressure of the hydraulic cylinders 3, 3 is supplied from a hydraulic pressure control system 4 configured to keep the generated forces, that is, the pulling force applied to the slab 1 constant. This hydraulic pressure control system 4 includes a hydraulic power source 40 and a hydraulic cylinder 3.
, 3, and a pressure reducing valve 42 provided with a vent circuit 43 is interposed between the valve 41 and a directional switching valve 41 for switching the operating direction of the valves 41 and 3.

As is well known, the pressure reducing valve 42 prevents excessive pressure by operating a built-in pilot valve when the oil pressure in the main circuit connected to the hydraulic cylinders 3, 3, which are the destinations of oil pressure from the oil pressure source 40, increases excessively. The hydraulic pressure is released to the tank, and the main circuit is shut off by the accompanying operation of the main valve, thereby maintaining a constant hydraulic pressure in the main circuit, that is, the hydraulic pressure supplied to the hydraulic cylinders 3, 3. . Further, a vent circuit 43 attached to the pressure reducing valve 42 is provided with a medium pressure relief valve 44 in the middle of the oil path that opens the pilot chamber into which the hydraulic pressure applied to the pilot valve is introduced to the tank, as shown in the figure.
and a low-pressure relief valve 45 are arranged in parallel, and communication and isolation between these and the pilot chamber is performed by separate electromagnetic switching valves 46 and 47.

The relief pressure of the relief valve 44 is lower than the operating oil pressure of the pilot valve, and the relief pressure of the relief valve 45 is set lower than that of the relief valve 44. Therefore, when the electromagnetic switching valves 46 and 47 are in the illustrated switching position, that is, when the former is in the communicating position and the latter is in the blocking position, the relief valve 44 performs a relief operation prior to the operation of the pilot valve. As a result of the main valve of the pressure reducing valve 42 operating in accordance with this, the hydraulic pressure supplied to the hydraulic cylinders 3, 3 is limited to the relief pressure of the relief valve 44 or less. In addition, when the electromagnetic switching valves 46 and 47 are in the switching position opposite to that shown in the figure, the hydraulic cylinders 3 and 3
The hydraulic pressure supplied to the valve is limited to a value equal to or lower than the relief pressure of the relief valve 45 by the relief operation of the relief valve 45. Furthermore, solenoid switching valve
46 and 47 are both in the cutoff position, the hydraulic cylinder 3
, 3 is limited to the operating oil pressure of the pilot valve, in other words, the hydraulic pressure set to the pressure reducing valve 42 or less.

That is, the vent circuit 4 configured as shown in the figure
3, by switching the electromagnetic switching valves 46 and 47, the hydraulic pressure of the main circuit of the hydraulic pressure control system 4, that is, the hydraulic pressure supplied to the hydraulic cylinders 3, 3 is changed between the set pressure in the pressure reducing valve 42 and the relief valve 44, 45 relief pressures can be set to three different pressures. Note that the configuration of the vent circuit 43 is not limited to this, and it goes without saying that other configurations are possible, such as arranging more relief valves in parallel and setting the feed oil pressure in more stages.

In the hydraulic pressure control system 4 configured as described above, the method of the present invention includes an actuator 5 that introduces a predetermined hydraulic pressure into the vent circuit 43 in the middle of the vent circuit 43, and a pressure fluctuation of the actuator 5. This is carried out by respectively disposing pressure detectors 6 to detect the pressure. The operation of the actuator 5 is performed according to the operation command from the diagnostic device 7, and the detection result of the pressure detector 6 is transmitted to the diagnostic device 7.
Using this detection result, the diagnostic device 7 diagnoses an abnormality in the hydraulic pressure control system 4 according to the procedure described later.

FIG. 2 is a block diagram showing the internal configuration of the diagnostic device 7. As shown in FIG. As shown in the figure, the diagnostic device 7 includes a command device 70 that issues operation commands to the actuator 5, a setting memory 71 in which a reference waveform of pressure fluctuations that should be detected during normal operation is set, and a pressure detector 6 that detects this reference waveform. It is equipped with a determining section 72 that compares the results with each other to determine an abnormality, and a storage section 73 that sequentially stores the determination results by the determining section 72.

Operation commands from the command unit 70 are given to the actuator 5 at appropriate time intervals, and the actuator 5 introduces a predetermined hydraulic pressure into the vent circuit 43 in accordance with the operation commands. This causes a pressure fluctuation in the vent circuit 43, which is detected by the pressure detector 6 and input to the determination section 72. The operation command from the command unit 70 is also given to the setting memory 71 at the same timing as the output to the actuator 5, and according to this command, the setting memory 71 converts the stored reference waveform into the determination unit 72. Output to. The determination unit 72 compares the detection result of the pressure detector 6 and the reference waveform given from the setting memory 71 with respect to one or both of the amplitude of the two and the time until convergence to a constant pressure, and based on the comparison result, , for example, Good, Caution.
ion) and abnormality (Damage).

FIG. 3 is an explanatory diagram of the determination procedure in the determination section 72, in which the solid line represents an example of the waveform detected by the pressure detector 6, and the broken line represents the reference waveform given from the setting memory 71. There is. The pressure reducing valve 42 is normally open, and the vent circuit 43 is in communication with the main circuit of the hydraulic pressure control system 4. Therefore, pressure fluctuations occurring in the vent circuit 43 due to the operation of the actuator 5 are handled by the main circuit. The deterioration of the sealing performance in each part and the effects of abnormalities in various devices (not shown) arranged in the main circuit appear. Therefore, the waveform detected by the pressure detector 6 usually has a larger amplitude than the reference waveform,
Furthermore, it takes a longer time to converge to a constant pressure.

The determination unit 72 compares the detected waveform and the reference waveform, examines the amplitude difference ΔP between the two and the difference ΔT in time required for convergence (see FIG. 3 for both), and calculates each of these separately. Compare with a separately set judgment reference value. When performing the three-stage determination as described above, two types of determination reference values are set for each of the amplitude difference and the time difference, and the determination unit 7
2, when the obtained amplitude difference ΔP and time difference ΔT are less than a small reference value, it is determined as "normal", and when it is between the large and small reference values, it is judged as "caution", and when the obtained amplitude difference ΔP and time difference ΔT are below a small reference value, it is judged as "caution", and even larger reference value When the value exceeds the above, it is determined to be "abnormal". Note that three or more types of judgment reference values may be set to make a more detailed judgment of the state of the hydraulic pressure control system 4, or conversely, one judgment reference value may be set and two types of “normal” or “abnormal” may be set. It may also be possible to perform stage determination.

This determination in the determination unit 72 is performed by the command unit 7
It is performed each time the actuator 5 operates according to a command from 0,
This determination result, together with the amplitude difference ΔP and the time difference ΔT required for convergence in each case, is provided to the storage section 73 and sequentially stored therein, and further provided to the display section 8.

As shown in FIG. 2, the display unit 8 has an alarm 80
, a printer 81, a CRT display 82, and the like. The alarm 80 operates to notify the operator of an abnormality in the hydraulic pressure control system 4 by sounding in response to an operation command output from the determination unit 72 when the determination of "abnormality" or "caution" is made. to do. Further, the printer 81 has a determination unit 72
The CRT display 82 outputs the amplitude difference ΔP and time difference ΔT used in the above-mentioned determination, as well as a hard copy of the determination result based on these, and furthermore, the CRT display 82 displays the ΔP
The change state of ΔT and ΔT is displayed on the screen.
By visually checking these results, the operator can control the hydraulic pressure control system 4.
It is now possible to check changes in the state over time. In addition, more output devices may be installed on the display unit 8 as necessary to enable reliable notification of abnormality and status confirmation by the operator.

In this embodiment, the hydraulic pressure control system 4 has been described which is configured to keep the pulling force by the pinch rolls 2, 2 of the continuous casting equipment constant, but the method of the present invention Needless to say, the present invention can be applied to all kinds of hydraulic pressure control systems equipped with a vent circuit 43.

Furthermore, in this embodiment, a case will be explained in which the pressure fluctuation detected by the pressure detector 6 is compared with a reference waveform in normal conditions, and abnormality diagnosis is performed based on both the magnitude of the amplitude and the length of time until convergence. However, it is also possible to perform abnormality diagnosis using either one of them.

[0026]

Effects of the Invention As detailed above, in the method of the present invention, a predetermined hydraulic pressure is applied to the vent circuit of a pressure reducing valve, which is generally provided in a hydraulic pressure control system, in order to keep the hydraulic pressure supplied to the destination constant. To reliably automatically diagnose abnormalities in a hydraulic pressure control system by introducing a simple configuration in which pressure fluctuations occurring in the vent circuit are detected, and the amplitude and/or time until convergence of this fluctuation is investigated. This diagnosis is possible regardless of whether the hydraulic pressure control system is in operation or not, and can be applied to any hydraulic pressure control system equipped with a pressure reducing valve and its vent circuit. The invention has excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing the implementation state of the method of the present invention in a pull-out force control system using pinch rolls.

FIG. 2 is a block diagram showing an example of the internal configuration of a diagnostic device that performs abnormality diagnosis according to the method of the present invention.

FIG. 3 is an explanatory diagram of a procedure for abnormality determination according to the method of the present invention.

[Explanation of symbols]

1 Slab 2 Pinch roll 3 Hydraulic cylinder 4 Hydraulic pressure control system 5 Actuator 6 Pressure detector 7 Diagnostic equipment 8 Display section 42 Pressure reducing valve 43 Vent circuit

Claims (1)

[Claims] Claim 1. A method for automatically diagnosing abnormalities that occur in various parts of a hydraulic pressure control system that is equipped with a pressure reducing valve that maintains a constant supply pressure to a hydraulic power supply destination and a vent circuit thereof, wherein a predetermined Introducing hydraulic pressure, detecting the fluctuating pressure generated in the vent circuit at this time, and determining the degree of the abnormality based on the magnitude of the amplitude of the fluctuating pressure and/or the length of time until it converges to a constant pressure. An automatic diagnosis method for a hydraulic pressure control system characterized by: