JP2615291B2 - Hydraulic device diagnostic method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of diagnosing an abnormal condition or a tendency of deterioration of a hydraulic device which is used in a hydraulic pressure reducing device of a rolling equipment and whose valve opening is servo-controlled.

[0002]

2. Description of the Related Art In a rolling plant, a hydraulic pressure reduction device used to lower a rolling roller moves a spool of a switching valve in accordance with a valve opening command value (reference value) from a servo mechanism control unit. And the amount of oil flowing into the cylinder is controlled.

[0003] As a method of diagnosing an abnormality due to mechanical damage or the like of such a hydraulic pressure reduction device, conventionally, for example, a control current and a set value thereof when a closed loop servo system is configured before or during operation of a rolling facility. From the dither setting current value and dither setting frequency, the hysteresis characteristic of the servo valve body,
There has been proposed a method of obtaining a rolling-down gain characteristic, a frequency characteristic, and the like, and performing a diagnosis based on these characteristics.

[0004] As a method of diagnosing the tendency of deterioration,
A method of stopping automatic control operation of equipment and collecting necessary data while performing manual operation has been performed.

[0005]

The above-described conventional abnormality diagnosis method requires a large number of necessary data types, and the amount of calculation for obtaining each of the above characteristics using these data becomes extremely large. The load increases. For this reason, if the above-mentioned diagnostic method is adopted in an expert system for diagnosing the whole rolling equipment, there is a problem that a computer load is excessively applied to the diagnosis of the hydraulic press-down device, which interferes with the diagnosis of other parts.

Further, the above-mentioned conventional deterioration tendency diagnosis method has a problem that real-time diagnosis cannot be performed while operating the equipment, and a time for diagnosis needs to be provided during operation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a small amount of data processing and is capable of easily performing an abnormality diagnosis and a deterioration tendency diagnosis of a hydraulic device while the equipment is operating. The purpose of the present invention is to provide a diagnostic method.

[0008]

According to the present invention, a valve opening command value (reference value) and an actually measured value of a valve opening actually opened in accordance with the command value are collected to obtain a correlation between the two. The slope and the null value are obtained from the regression line of the correlation characteristic, and the hysteresis value is obtained from the relationship between the regression line and the actually measured value with respect to the valve opening command value. If the slope of the regression line deviates from a preset normal value, it is diagnosed that the hydraulic device has a spring abnormality. If the null value of the regression line deviates from a preset normal value, it is diagnosed that the oil passage of the hydraulic device is worn. If the hysteresis value is out of the normal range set in advance, it is diagnosed that the operation of the spool of the hydraulic device is abnormal.

[0009]

In the correlation characteristic between the reference value and the measured value in the normal state shown in FIG. 3 (A), the slope of the regression line, the null value and the hysteresis value are changed depending on the abnormal state of the hydraulic device. (C) and (D), the correlation characteristic is displayed and observed, or compared with the abnormality determination value to determine whether the spring of the hydraulic device is abnormal.
The wear of the oil passage of the hydraulic device and the abnormal operation of the spool of the hydraulic device can be known, and the tendency of deterioration can be known.

[0010]

FIG. 1 shows an embodiment of a diagnostic apparatus for performing a diagnostic method according to the present invention.

In FIG. 1, a steel plate 1 has a pair of backup rollers 2a, 2b and work rollers 3a, 3b.
Is rolled. The hydraulic pressure reduction device 4 for reducing the pressure of the backup roller 2a controls the amount of reduction by moving the spool of the switching valve to control the hydraulic pressure.

FIG. 2A shows a spool 5 of the hydraulic pressure reduction device 4.
The configuration in the vicinity is shown.

The spool 5 is provided in oil passages 6 and 7 communicating with a cylinder (not shown), and is driven in the directions of arrows a and b by an electromagnetic mechanism (not shown). Therefore, depending on the position of the spool 5, the passages 6, 7
The opening (valve opening) is adjusted to control the oil pressure. A spring 8 is connected to one end of the spool 5, and constantly biases the spool 5 in the direction of arrow b.

Referring again to FIG. 1, a servo mechanism control unit 9 for controlling the hydraulic pressure reduction device 4
A reference value as a command signal of the movement amount of the spool 5, that is, the valve opening is sent. The electromagnetic mechanism that drives the spool 5 is excited by a current corresponding to the reference value, and moves the spool 5.

At this time, the movement amount of the actual movement of the spool 5 is detected by a position sensor (not shown), and is fed back to the servo mechanism control section 9 as an actual value.

Further, the amount of reduction of the backup roller 2a reduced according to the hydraulic pressure controlled by the movement of the spool 5 is detected by the position sensor 10 and the AGC control unit 11
Will be fed back. The AGC control section 11 supplies a control signal for controlling a loop gain to the servo mechanism control section 9 in accordance with the reduction amount and a target value such as a plate thickness.

A sub-control loop for controlling the movement of the spool 5 is formed between the servo mechanism control section 9 and the hydraulic pressure reduction device 4. The servo mechanism controller 9 creates a reference value based on the actual value fed back and the control signal from the AGC controller 11.

The reference value and the actual value are stored in the data input unit 12.
Are sampled and recorded at predetermined intervals. The data processing operation unit 13 obtains a correlation characteristic between the reference value and the actual value collected by the data input unit 12,
The obtained correlation characteristic is displayed on the display unit 14 or added to the abnormality determination unit 15. Other systems 1 such as an external control system and a diagnostic system as needed
Sent to 6.

Next, the above-mentioned correlation characteristic and abnormal state will be described.

FIG. 2B is an enlarged view of the vicinity of a portion for opening and closing the oil passage 6 of the spool 5 in FIG. 2A. The abnormality of the hydraulic pressure reduction device 4 that can be diagnosed in the present embodiment is as follows.

(1) Abrasion indicated by a dotted line of an edge 5a of a portion for opening and closing the passage 6 of the spool 5 in FIG. 2B.

(2) The edge 5a shown in FIG.
Abrasion indicated by a dotted line at a corner 6a of the passage 6 with which the contact is made.

(3) Wear of the spring 8 in FIG.

(4) Other mechanical rattling, catching, and center line deviation of the spool 5 (FIG. 2B).

(5) Abnormalities such as set of the spring 8.

And so on.

FIG. 3 shows a correlation characteristic between the reference value and the actual value in a normal state and in an abnormal state.

If the hydraulic pressure reduction device 4 is normal, the reference value and the actual value are substantially the same. Therefore, as shown in FIG. 3A, points where actual values are plotted against reference values are gathered near an ideal straight line 20 having a slope of 45 °.

When the abnormality (4) occurs, a phenomenon occurs in which a large difference occurs between the reference value and the actually measured value of the moving operation of the spool 5, and as shown in FIG. The upper hysteresis value in which the plot points are dispersed over a wide range, and the spread of the plot points exceeds a predetermined range above the regression line 21 and falls within an ellipse above the regression line 21;
Or, the regression line 2 exceeds a predetermined range below the regression line 21.
A lower hysteresis value appears that falls within the ellipse below 1. This abnormality is called a hysteresis value abnormality.

When the abnormalities (3) and (5) occur, as shown in FIG. 3C, the inclination angle of the regression line 21 is, for example, 55 °, and the ideal straight line 20 in FIG. Tilt angle of 45
゜ It becomes bigger. This abnormality is called an inclination abnormality.

When the above-mentioned abnormalities (1) and (2) occur, the regression line 21 is shifted upward by Δy from the normal position, as shown in FIG. This abnormality is referred to as a null value abnormality.

Accordingly, the correlation characteristic, the regression line 21 and the like obtained by the data processing operation unit 13 are displayed on the display unit 14 in the form of a graph as shown in FIG. It can be diagnosed whether an abnormality, a null value abnormality, or the like has occurred, or whether a tendency toward these abnormalities has started.

Further, data such as correlation characteristics and a regression line is sent to the abnormality judging unit 15, and the abnormality judging unit 15 judges and displays an abnormality by comparing an abnormality judgment value set for each abnormality with the above data. Displayed by the unit 14.

The backup roller 2b has the same control loop as the backup roller 2a. Further, a load cell 17 for detecting a rolling load on the backup roller 2b and a sensor 18 for detecting the steel sheet 1 in the rolling line are provided, and a detection signal thereof is applied to the data input unit 12. When the sensor 18 detects that the steel sheet 1 exists in the rolling line and the load cell 17 detects a constant load, it is assumed that the equipment is operating, and in this operating state, the data input unit 12 sets the reference value. And the actual value are collected.

[0035]

According to the present invention, the amount of movement of the spool, that is, the reference value indicating the valve opening, is obtained from the correlation between the reference value and the actually measured value of the valve opening actually opened. Diagnosis of hydraulic device spring abnormalities, wear of oil passages, and spool operation abnormalities is immediately performed based on the slope of the regression line, the null value, and the hysteresis value, so the amount of data required for the diagnosis is small. As a result, the load on the computer is reduced, and diagnosis can be performed in real time while operating the equipment. In particular, the diagnosis of the operation abnormality of the spool of the hydraulic device is also performed based on the hysteresis value, so that the diagnosis performance can be improved. Furthermore, deterioration tendency diagnosis can be performed quantitatively at an arbitrary diagnosis pitch, and failures can be predicted in advance by using a trend management graph, which can prevent accidental serious accidents of hydraulic equipment and improve stable operation and productivity. Can be expected.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of a diagnostic apparatus that performs a diagnostic method according to the present invention.

FIG. 2 is a sectional view showing a main part of a hydraulic pressure reduction device.

FIG. 3 is a characteristic diagram showing a correlation characteristic in an abnormal state diagnosed by the present invention.

[Explanation of symbols]

 4 Hydraulic pressure lowering device 9 Servo mechanism control unit 5 Spool 12 Data input unit 13 Data processing unit 15 Abnormality judgment unit

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-54-25377 (JP, A) JP-A-58-119009 (JP, A) JP-A-60-19207 (JP, A) JP-A 63-19763 172004 (JP, A) JP-A-63-199986 (JP, A)

Claims (1)

(57) [Claims] A reference value of a valve opening in an oil passage specified by a servo mechanism control unit that controls a valve opening of a hydraulic device is sampled and accumulated, and the valve is actually opened according to the reference value. A hydraulic device that detects a valve opening, samples and accumulates the measured value as an actual measurement value, obtains a regression line of a correlation characteristic between the accumulated reference value and the actual measurement value, and diagnoses the hydraulic device based on the regression line. The diagnostic method according to claim 1, wherein the slope and the null value are obtained from the regression line, and a hysteresis value is obtained from the relationship between the regression line and the actually measured value with respect to the reference value. If it is off, it is diagnosed that the spring of the hydraulic device is abnormal, and if the null value of the regression line is out of the preset normal value, it is diagnosed that the oil passage of the hydraulic device is worn, If the hysteresis value is outside the normal range which is set in advance, the diagnostic method of the hydraulic device, characterized in that the diagnosis of operational abnormality of the spool of the hydraulic system.