JPH0261843B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a device for diagnosing the presence or absence of an abnormality in various rolling mill hydraulic reduction devices arranged in tandem. [Background of the Invention] Conventionally, in the rolling operation of this type of hydraulic rolling device, the operator directly reads various values on the main control panel for the rolling device, and if there is an abnormality, the operator independently judges based on experience and takes appropriate action. The rolling operation was started by adjusting the values of the operator. but,
In such a method, the evaluation of the rolling dynamic characteristics in the rolling device is qualitative, and it is expected that there will be variations in each parameter governing the rolling state.
As a result, it is thought that variations have a large effect on the product board thickness. In addition, the servo valve of the flow control valve, which is a key component of the pressure reduction device,
It is difficult to predict the dynamic characteristics, and it has not been possible to quantitatively determine the exchange pitch setting of the servo system. By the way, in a hydraulic lowering device that constitutes a closed-loop position servo system from a lowering jack and a servo valve, the spool of the servo valve does not lock and the control current can drift in a closed loop when there is no lowering command. It is important to ensure that the control current is as small as possible, and that there is no difference in the control current between the left and right rolling devices, in order to improve product yield (high quality) and ensure smooth rolling operations. Therefore, there is a need for an apparatus that can constantly and periodically diagnose the presence or absence of abnormalities in parameters such as the control current, the dynamic characteristics of the servo valve, and the displacement of the reduction jack before or during rolling. A method of diagnosing the presence or absence of abnormalities in hydraulic equipment such as steam turbines by detecting the pressure, flow rate, and amount of wear of hydraulic oil and comparing the relationship between these detected values with preset reference values and tolerance deviations. is known from Japanese Patent Application Laid-Open No. 58-213227. This diagnostic method periodically determines the relationship between cylinder pressure and valve displacement in a closed-loop servo system, thereby diagnosing mechanical damage inside the cylinder and enabling high-speed cylinder switching in the event of a steam turbine emergency. This is how it was done. However, this diagnostic method is not suitable for diagnosing abnormalities such as the control current and displacement of the reduction jack in the closed-loop servo system as described above, which is used to improve product yield, such as in the hydraulic reduction device of a rolling mill. . [Object 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, which is mainly intended to improve the yield of rolled products. [Summary of the Invention] In order to achieve the above object, the present invention includes a control current detection unit that detects a control current when a closed loop servo system is configured before or during rolling in a rolling device, a set value of the control current, and a dither. an allowable deviation value storage unit storing predetermined allowable deviation values regarding the set current value and the dither set frequency; a detected value of the control current detected by the control current detection unit; and a set value of the control current;
A deviation calculation unit that calculates deviation values regarding the control current, dither current, and dither frequency using the dither setting current value and dither setting frequency, and deviations regarding the control current, dither current, and dither frequency obtained by the deviation calculation unit. a constant diagnostic device comprising a deviation value comparison unit that compares at least one deviation value among the values and an allowable deviation value stored in an allowable deviation value storage unit; and a constant diagnostic device that detects whether there is an abnormality in the lowering device. a reference wave signal generating section that outputs a reference wave signal having an arbitrary magnitude to the rolling device; a dynamic characteristic detecting section that detects a rolling dynamic characteristic signal of the rolling device in response to the reference wave signal; A deviation characteristic calculation section that calculates the deviation characteristic value of the rolling down dynamic characteristic from the characteristic signal, an allowable dynamic characteristic value storage section that stores the allowable rolling down dynamic characteristic value predetermined regarding the value of the reference wave signal, and a deviation characteristic calculation section that calculates the deviation characteristic value of the rolling down dynamic characteristic from the characteristic signal. The present invention is characterized in that it is equipped with a periodic large-diagnosis device comprising a dynamic characteristic value comparison section that compares the deviation characteristic value obtained by the deviation characteristic value with the allowable reduction dynamic characteristic value stored in the allowable dynamic characteristic value storage section. [Embodiment of the Invention] An embodiment of the apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic structural diagram of one stand of a rolling mill hydraulic rolling-down device in which 6 to 7 stands are arranged in tandem and configured to apply an abnormality diagnosis device for a rolling mill hydraulic rolling-down device according to the present invention. A rolling mill hydraulic rolling device generally includes two systems: a drive side and an operation side. For example, taking the drive side as an example, a pair of work rolls 1a, 1
a', intermediate rolls 2a, 2a', back-up rolls 3a, 3a', a reduction jack 4 consisting of a reduction ram 4a and a reduction cylinder 4b, a direct-acting servo valve 6a of a flow rate control valve that controls the position of the reduction jack 4 . , a main control panel 7 for controlling the servo valve 6a, and a lowering jack 4 for detecting the displacement of the lowering jack 4.
It consists of a displacement gauge 5 built into the roller, a load cell 10 for detecting the rolling force during rolling, and the like. 11
1 is an oil tank, 12 is a hydraulic power unit equipped with these hydraulic devices, and three systems of piping 13 to 15 are connected to the servo valve 6a. Piping 13
is a piping system to the reduction jack 4 , piping 14 is an oil drainage path from the reduction jack 4 , and piping 15 is a piping system that supplies high pressure oil from the pump P to the servo valve 6a. Next, the operation of the hydraulic pressure lowering device having the above structure will be explained. First, the servo valve 6a is driven based on the target command applied to the main control panel 7, and the hydraulic power unit 12 supplies an amount of high pressure oil commensurate with the amount of drive displacement, and this supplied high pressure oil is applied to the servo valve 6a and By being led into the reduction jack 4 through the pipe 13, the reduction ram 4a of the reduction jack 4 is driven. At this time, the displacement of the reduction jack 4 is detected by the displacement meter 5, and a feedback displacement signal 9a is generated.
The feedback current is fed back to the main control panel 7 and compared with the target command input to the main control panel 7. The resulting deviation current 8a is amplified and input to the servo valve 6a, and this input signal causes the servo to be activated. Basically, the gap of the work rolls 1a, 1a' is directly controlled by the reduction jack 4 by controlling the valve 6a. That is, it is a closed-loop position servo system and is characterized in that the thickness of the rolled material M interposed between the work rolls 1a and 1a' is controlled in microns. Furthermore, displacement due to deflection of the roll system is detected and corrected by the load cell 10, and AGC (Automatic Gage Control) is basically configured to control the gap between the rolls at a constant level. That is, when pushing up the reduction jack 4 according to the target command, an oil passage is configured from piping 15 to 13, and when pushing it down, an oil passage from piping system 13 to 14 is configured, thereby reducing the pressure from servo valve 6a. The thickness of the rolled material M is controlled by directly driving the reduction jack 4 with oil. The direct-acting servo valve 6a described here may be a nozzle flapper type servo valve, a jet pipe type servo valve, or the like. FIG. 2 is a flowchart showing an embodiment of the abnormality diagnosis device for a rolling mill hydraulic rolling device of the present invention. In Figure 2, the diagnostic functions are roughly divided into two: continuous diagnosis A, which is always performed during rolling or before the start of rolling, and periodic diagnosis B, which is periodically performed at each stand before the start of rolling. In diagnosis B, when diagnosing the entire rolling down device, periodic major diagnosis B ₁ is used.
Diagnosing the function of a single servo valve, which is an important component of the lowering device, is classified as periodic minor diagnosis _B2 . In the constant diagnosis A, by detecting the control current when the closed-loop position servo system is configured during rolling or before the start of rolling from the control panel 7, the amount of drift of the control current, and the dither current and frequency superimposed on the control current are determined. By detecting the amount of deviation from the set value and comparing it with each allowable value, it is diagnosed whether or not these parameters are in an abnormal state. If an abnormality is found, the details of the abnormality will be displayed on the CRT.
In addition to displaying the information on a display device such as the above, appropriate countermeasure comments for the content of the abnormality are also displayed on the same display device as described above. This constant diagnosis may be performed on any stand during rolling, or may be performed on each stand before rolling starts and prior to periodic diagnosis. That is, the control current i is taken in from the control current terminal of the main control panel 7 of the rolling mill hydraulic rolling device that constitutes the closed loop position servo system, and this control current i is detected and the amount of drift in the control current i, that is, the deviation current is detected. Δi and the dither signal superimposed on the control current i are divided into the deviation amount Δi _d from the dither setting current i _d and the deviation amount Δf _d from the dither setting frequency f _d and are calculated in advance in a storage device such as a microcomputer. These judgment conditions are satisfied by comparing the allowable values for these parameters stored in the unit, such as allowable deviation current ∆i〓, allowable dither frequency deviation ∆f〓〓, and allowable current deviation ∆i〓〓. The presence or absence of an abnormality is diagnosed based on whether or not it occurs. If there is no abnormality as a result of this constant diagnosis A,
Furthermore, it is necessary to quantitatively check whether each rolling device is capable of rolling, and periodic diagnosis B is performed on each rolling device to diagnose the rolling dynamic characteristics of each rolling device. On the other hand, if there is an abnormality in the continuous diagnosis A, the details of the abnormality will be displayed on a display device such as a CRT, and the dither circuit and Nvll current circuit will be inspected, and if there is no abnormality in these circuits, the voltage will be further reduced. It has become necessary to diagnose the entire system, and we have moved on to the next diagnostic step, namely periodic major diagnosis _B1 . In this periodic major diagnosis B ₁ , we diagnose the basic rolling dynamic characteristics that directly affect the product, such as the quick response and stability of the entire rolling equipment. In this way, understanding the rolling dynamic characteristics of the rolling device before the start of rolling is important not only to improve the yield of rolled products and the operating rate, but also to predict the life of the component parts. In this periodic major diagnosis, for example, work roll 1
A method of investigating the phenomenon in which the rolled material M is caught between a and 1a', that is, the transient response characteristics, is to apply a stepwise reference input of an arbitrary size and evaluate the quality of the response of the system. It is. That is, for example, a stepwise reference wave is input to the closed-loop position servo system of the hydraulic lowering device to be diagnosed, and the detected displacement of the lowering jack in the time domain is input into a microcomputer using the displacement meter 5 built into the lowering jack 4 . , maximum displacement y _Cnax of this displacement detection value reduction jack 4, rise time t _r , settling time t _S
Calculate deviation values from parameters that represent responsiveness and stability, and calculate these deviation values and allowable values of the parameters, such as the maximum allowable displacement of the jacking jack.
It is compared with y _C 〓, allowable rise time t _r 〓, and allowable settling time t _S 〓, and it is diagnosed whether or not there is an abnormality in the rolling device during rolling depending on whether these judgment conditions are satisfied. As a result of this diagnosis, if the deviation value of the screw-down jack is less than the allowable value, a message indicating that there is no abnormality is displayed, and a signal to this effect is transmitted to the main control panel 7 of the screw-down device by blinking or sound. On the other hand, if the deviation value of the reduction jack exceeds the allowable value, an abnormality is displayed and the diagnosis result is recorded in a recording device such as a printer. If no abnormality is found in the above periodic major diagnosis _B1 , the process moves to the next constant diagnosis A of the rolling down device. However, if there is an abnormality in periodic major diagnosis _B1 ,
Then move on to periodic minor diagnosis B ₂ . This periodic small diagnosis _B2 is based on the diagnosis of the static and dynamic characteristics of the servo valve itself. That is, the hysteresis characteristics, pressure gain characteristics, frequency characteristics, etc. of the servo valve body are diagnosed. Originally, in the hysteresis characteristic, the input current i
Items to be considered include the linearity between and the spool displacement x _s , the width of the dead zone due to poor alignment, and the width of hysteresis, but here we will explain the case of diagnosing the width of the dead zone. That is, a reference sine wave is input to the servo valve to be diagnosed, the input current to the servo valve and the spool displacement x _S of the servo valve are detected by a displacement meter, and the width of the dead zone ε is determined from the relationship between the input current and spool displacement characteristics. Calculate the predetermined allowable dead zone width ε〓
Compare with. As a result of the diagnosis, if ε>ε〓 and there is an abnormality, the comparison result is displayed on the display device, the result is recorded in the recording device, and comments on appropriate countermeasures for the abnormality are provided, for example, for servo valve spool positioning. If a rubber spring is used, the display device indicates that the rubber spring should be replaced with a new one. Similarly, diagnose the pressure gain characteristics and compare the spool displacement x ₀ required for the servo valve's control pressure P _C to reach a predetermined pressure from zero with the allowable value x ₀ 〓.
If x ₀ ＞x ₀ 〓, it is diagnosed as abnormal and x ₀ ＜x ₀ 〓
When , it is diagnosed that there is no abnormality. In the case of the above abnormality, an appropriate comment regarding the abnormality content, for example,
Comments such as replacing the spool and sleeve with new ones are displayed on the display device. Further, even when there is no abnormality, by displaying the comparison results of pressure gain characteristics, the state of wear of the edges of the spool and sleeve can be quantitatively predicted to some extent. Therefore, it is possible to predict the lifespan of important parts, and it is possible to quantitatively determine maintenance cycles and the like. Regarding the frequency characteristics of a single servo valve,
The transfer function is identified from the input command current i and spool displacement x _S of the captured analog data. As a result, the predetermined response frequency f ₉₀ 〓 with a phase delay of 90° and the measured response value f ₉₀ are compared, and if f ₉₀ > f ₉₀ 〓, it is diagnosed that there is no abnormality, and if f ₉₀ < f ₉₀ 〓 If so, it is diagnosed that there is an abnormality, the comparison result is displayed on the display, and an appropriate comment is made regarding the abnormality, for example, it is assumed that the characteristics of the rubber spring have deteriorated, so the rubber spring is replaced with a new one. Display comments such as "I do" on the display device. If the spring used for positioning the spool of the servo valve is a rubber spring, the periodic mini-diagnosis above will show that the spring constant has decreased due to deterioration of the rubber itself due to heat or swelling due to hydraulic oil, or hysteresis has occurred. It becomes possible to predict defects such as an increase in the width of the dead zone before rolling. Furthermore, from the comparison results when there is no abnormality,
It is possible to quantitatively predict to some extent how the spring constant of the rubber spring changes over time, which has a large effect on the value of _f90 , and it is also possible to quantitatively select the replacement pitch of the rubber spring. If there are no abnormalities in the above three diagnostic items, that is, hysteresis characteristics, pressure gain characteristics, and frequency characteristics, the display will indicate that the next stand will be diagnosed, and if there is an abnormality in any of the diagnostic items. If a stand is found, appropriate measures are taken based on the comments, and then a message is displayed on the display indicating that the next stand will be diagnosed in the same way as when there is no abnormality. Furthermore, such a diagnostic operation is repeated for the required number of stands, and when all the stands are diagnosed as having no abnormality, the rolling preparation completion command is sent to the main control panel 7 of the rolling device by blinking or audible, and the process ends. . FIG. 3 shows a flowchart regarding detailed diagnosis contents of the hysteresis characteristics of the periodic minor diagnosis items. In FIG. 3, the diagnosis flow regarding the width of the dead zone is omitted since it was explained in detail in FIG. 2, and the diagnosis flow regarding the relationship between the input current i and the spool displacement _xs and the width of the hysteresis will be described. First, input a reference sine wave to the servo valve to be diagnosed, take in the input current i and spool displacement x _s ,
Displacement difference Δx _s between the spool displacement s _st corresponding to the positive polarity of the input current and the spool displacement x _sc corresponding to the negative polarity
is calculated, and compared with the predetermined tolerance value Δx _S 〓, Δx _S
When <Δx _S 〓, it is diagnosed that there is no abnormality, and when Δx _s > Δx _s 〓, it is diagnosed that there is an abnormality. Furthermore, in the case of an abnormality, the comparison results are displayed. It can be assumed that the reason why the variation in the spring constant exceeds the allowable value is that the rubber spring of the servo valve swells, and the spring constant differs significantly between compression and tension. Therefore, as a countermeasure against the abnormality, a message indicating that the rubber spring should be replaced with a new one is displayed on the display device. Furthermore, even if there is no abnormality, it is possible to quantitatively predict the lifespan of the rubber spring from the comparison result displayed on the display device, which is effective in determining when to replace the rubber spring. On the other hand, regarding the width of the hysteresis, as in the case of the width of the dead zone, take the input current i and the spool _displacement When δ>δ〓, it is diagnosed that there is no abnormality.
The diagnosis result will be displayed on the display, and since the cause of the abnormality is thought to be swelling of the rubber spring,
As a countermeasure comment, a message indicating that the rubber spring should be replaced with a new one is displayed. Furthermore, if there is no abnormality, the comparison result is displayed on the display device, so the width of hysteresis over time is compared with the data for the new product stored in the memory unit of the microcomputer in advance, and how it compares. You can see if things are changing.
Moreover, by comparing it with the limit performance of the rubber spring, it is possible to quantitatively grasp the usable period. Therefore, the replacement pitch of the rubber spring can be determined quantitatively, which enables safe operation of the system and greatly contributes to improving product yield. FIG. 4 is a block diagram for explaining the hardware configuration of the apparatus of the present invention. FIG. 4 shows the case of regular diagnosis A and periodic major diagnosis _B1 shown in the flowchart of FIG. 16 is the hydraulic pressure reduction device targeted for diagnosis; 17
18 is the transmission line for the control current signal, 18 is the transmission line for the displacement signal of the lowering jack, and 19 is the hydraulic lowering device 16.
2 shows an input signal generation device that inputs a step-like reference wave to the input signal. Regular diagnosis is performed prior to periodic diagnosis. first,
The control current i is input from the control current terminal of the main control panel of the hydraulic lowering device 16 constituting the closed-loop position control system to the data input device 20 through the signal transmission line 17, and the analog data input by the signal conversion device 21 is further input. The converted data is converted into digital data, and the data is loaded into the storage section of the microcomputer 22 in synchronization with the data loading timing of the timer 23. On the other hand, the computer 22
Compares the permissible deviation value of the control current, dither current, and dither frequency stored in the storage unit with the detected values corresponding to these parameters, and determines whether the deviation value is below the permissible value. If the deviation value exceeds the allowable value, it is diagnosed that there is an abnormality, and
These diagnostic results including countermeasure comments for the abnormalities are displayed on the display device 24, and the diagnostic results are recorded in the recording device 25, thereby completing the regular diagnosis. Following this regular diagnosis, periodic major diagnosis shall continue. In the periodic major diagnosis, the input signal generator 19
A step-like reference wave having an arbitrary size is input to the hydraulic lowering device 16, and the displacement response of the lowering jack in this case is detected by the displacement meter 5, and is connected to the data input device 20 via the signal transmission line 18. It's crowded. Next, the analog quantity is converted into a digital quantity by the signal converter 21, and a certain timing for data capture is set by the timer 23, and the data is captured into the microcomputer 22 in consideration of the set capture timing. . Here, if the displacement of the reduction jack is a digital amount, it may be directly input to the microcomputer 22 through the timer 23 without going through the signal converter 21. The microcomputer 22 processes and calculates the displacement response of the screw down jack in the time domain, and calculates the settings for the maximum displacement, rise time, and settling time of the screw down jack that have been recorded in advance in the storage section of the microcomputer 22, as well as these values. Compare the detected values corresponding to the parameters, and if all of these detected values are below the set value, it is diagnosed that there is no abnormality.
Conversely, if the detected value exceeds the set value, it is diagnosed that there is an abnormality and the diagnosis result is displayed on the display device 24.
and record the diagnosis results in the recording device 25. Such periodic diagnosis is repeated as many times as there are stands to be diagnosed. FIG. 5 is a block diagram for explaining the hardware configuration in periodic small diagnosis _B2 shown in the flowchart of FIG. In FIG. 5, 26 is a single servo valve to be diagnosed, 27 is a displacement meter that detects the spool displacement of the servo valve, 28 is a pressure sensor that detects the control pressure P _C of the servo valve in pressure gain characteristics, and 29 is the spool displacement. 30 _is a signal transmission line for the control pressure P _C , and 31 is a transmission line for the input current signal to the servo valve. Incidentally, since the specific diagnosis method is exactly the same as that shown in FIG. 4, the details will be omitted. FIG. 6 is a diagram for explaining one diagnosis result in this diagnostic apparatus, and shows a case where an abnormality is diagnosed by regular major diagnosis _B1 . That is, if there is an abnormality, the entire hydraulic pressure reduction device to be diagnosed is displayed on a display device such as a CRT. In addition, the displacement of the reduction jack (CYL
The diagnostic results regarding displacement, rise time, and settling time are displayed in comparison with the set values. From this, the detected values regarding the rise time and settling time of the rolling jack satisfy the set values and are not abnormal, but on the other hand, the detected value of the maximum displacement of the rolling jack is 392.19 μm.
exceeds the set value of 320 μm, and according to regular major diagnosis, it can be diagnosed that the lowering device as a whole is abnormal. Therefore, it can be seen that a more detailed diagnosis, that is, a periodic small diagnosis is necessary. Figure 7 shows the results of the periodic major diagnosis shown in Figure 6.
This shows the displacement response waveform of the downward jack displayed on a display device such as a CRT. As is clear from Figure 7,
The maximum displacement _ycnax of the reduction jack greatly exceeds the set value _yc〓 . As described above, according to this embodiment, the rolling dynamic characteristics of the rolling device can be quantitatively grasped before the start of rolling or during rolling through constant diagnosis and periodic diagnosis.
Based on the results, it can be determined whether rolling is possible or not, and erroneous operations can be prevented. Therefore, serious troubles due to poor characteristics of the rolling mill hydraulic rolling device can be prevented. In addition, by conducting periodic small diagnostics on the servo valve, which is a key component of the lowering device, we can not only judge whether the basic static and dynamic characteristics of the servo valve are good or bad, but also confirm that there is no abnormality as a result of the diagnosis. In some cases, it is possible to predict the service life of important components of the servovalve, such as spool sleeves and rubber springs. Therefore, it is possible to quantitatively determine the replacement pitch of important parts. [Effects of the Invention] According to the device of the present invention, constant diagnosis and periodic diagnosis of the presence or absence of abnormalities in each hydraulic rolling device arranged in tandem are performed before or during rolling, so that smooth rolling operation is possible. As a result, the amount of off-gauge (rolled material outside the allowable dimensional range) of rolled products can be significantly reduced, and the product yield of rolled products can be improved. In addition, serious disasters due to poor characteristics of the hydraulic lowering device can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a schematic overall configuration diagram showing a rolling mill hydraulic reduction device to which the diagnostic device of the present invention is applied, and Fig. 2 is an example of the implementation of constant diagnosis and periodic major diagnosis in the abnormality diagnosis device for the rolling mill hydraulic reduction device of the present invention. FIG. 3 is a flowchart showing an example of periodic small diagnosis in the device of the present invention; FIGS. 4 and 5 are block diagrams showing the hardware configuration of the present invention; FIGS. FIG. 7 is a diagram showing one diagnosis result in the apparatus of the present invention. 1a, 1a'... work roll, 2a, 2a'... intermediate roll, 3a, 3a'... back up roll,
4...Download jack, 5...Displacement meter, 6a, 6b
...Servo valve, A...Continuous diagnosis, _B1 ...Regular major diagnosis, _B2 ...Regular minor diagnosis.

Claims (1)

[Scope of Claims] 1. In a rolling mill hydraulic rolling device configured as a closed-loop servo system, a control current detection unit that detects a control current when the closed-loop servo system is configured before or during rolling in the rolling device; a permissible deviation value storage unit storing predetermined permissible deviation values regarding the set value of , the dither set current value, and the dither set frequency; a detected value of the control current detected by the control current detection unit; and a set value of the control current. , a deviation calculation section that calculates deviation values regarding the control current, dither current, and dither frequency using the dither setting current value and the dither setting frequency, respectively; a constant diagnostic device comprising a deviation value comparison unit that compares at least one deviation value among the deviation values and an allowable deviation value stored in the allowable deviation value storage unit; and a constant diagnostic device that detects an abnormality in the lowering device. a reference wave signal generating section that outputs a reference wave signal having an arbitrary magnitude to the rolling down device, regardless of whether it is present, and a dynamic characteristic detection section that detects a rolling down dynamic characteristic signal of the rolling down device in response to the reference wave signal; , a deviation characteristic calculation section that calculates a deviation characteristic value of the rolling down dynamic characteristic from the detected rolling down dynamic characteristic signal, and an allowable dynamic characteristic value storage section that stores a predetermined allowable rolling down dynamic characteristic value with respect to the value of the reference wave signal. , a regular large diagnostic device comprising a dynamic characteristic value comparison unit that compares the deviation characteristic value obtained by the deviation characteristic calculation unit and the allowable reduction dynamic characteristic value stored in the allowable dynamic characteristic value storage unit. An abnormality diagnosis device for a rolling mill hydraulic reduction device, which is characterized by: 2. If there is an abnormality in the reduction device as diagnosed by the periodic large diagnostic device, the device is characterized by having a periodic small diagnostic device that diagnoses whether or not there is an abnormality in the basic static and dynamic characteristics of the flow control valve of the reduction device. An abnormality diagnosis device for a rolling mill hydraulic reduction device according to claim 1. 3. The regular large diagnostic device detects the displacement response of the screw down jack in the time domain using a displacement meter provided on the hydraulic jack of the screw down device, and determines the maximum displacement, rise time, and settling time of the screw down jack from the detected displacement response. The rolling mill hydraulic pressure according to claim 1, further comprising means for calculating deviation values and comparing these deviation values with predetermined tolerance values to diagnose the presence or absence of an abnormality in the rolling device. Abnormality diagnosis device for lower equipment. 4. The periodic small diagnostic device detects the hysteresis characteristics, pressure gain characteristics, and frequency characteristics of the flow control valve using a displacement meter and a pressure sensor provided in the flow control valve,
Claims characterized by having means for calculating a deviation value from these detected values and set values, comparing these deviation values with a predetermined tolerance value, and diagnosing the presence or absence of an abnormality in the flow control valve. 2. An abnormality diagnosis device for a rolling mill hydraulic reduction device according to item 2.