JPH04200666A - Method for inspecting sensor for detecting abnormality of spray nozzle - Google Patents

Abstract

PURPOSE:To decide whether a spray nozzle is normal or not by providing a fluid injector for a sound detecting sensor at the standby position of a measuring capsule, injecting a fixed amt. of fluid to the sensor by the injector and comparing the output signal of the sensor at that time with a preset reference value. CONSTITUTION:The inspection of the injection state of a spray nozzle in the secondary cooling zone is finished by an AE sensor, a measuring capsule is extracted along with a dummy bar and stopped at a standby position, an air injector is then turned on to inject air on each detecting plate 3 from an air injection pipe 7, and the output signal of each AE sensor is inputted to a computer 11. The air is injected for a specified time, the output value of each AE sensor is stored in the computer 11, and the output value of the AE sensor is compared with the reference value preset by a setting device 12. When the measured value of the AE sensor is coincident with or close to the reference value, the nozzle is supposed as normal. When the measured value is different from the reference value, the nozzle is considered as abnormality, and the result is indicated on an indicator 13. The nozzle is inspected by the AE sensor in this way and always kept normal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for inspecting a device for determining the quality of the jetting condition of a spray nozzle. The present invention relates to a sensor testing method for simply, quickly, and accurately detecting the quality of a sensor that detects a state.

BACKGROUND ART Cooling of a slab in the secondary cooling zone of a continuous casting machine greatly affects not only the surface quality of the slab but also its internal quality, so it is necessary to homogenize the cooling effect.

Therefore, in the secondary cooling zone of a continuous casting machine, hundreds to dozens of spray nozzles are used per strand.

However, these nozzles are easily clogged by foreign objects in the cooling water, and in order to ensure uniform cooling of the slab, it is important to prevent nozzle clogging as much as possible. It is necessary to accurately understand the situation and determine whether each nozzle is abnormal or normal.

Therefore, various devices have been proposed that are capable of detecting the jetting state of a nozzle and determining its quality.

For example, in Japanese Patent Application Laid-open No. 50-202959, a pressure gauge and a flow meter are disposed in the middle of a supply pipe connected to a nozzle, and the detected values are used to detect a blocked nozzle using a predetermined calculation formula. A device configured to calculate numbers is disclosed, and Japanese Patent Application Laid-Open No. 61-249562 discloses a see-through window that is provided facing the jet stream from the nozzle, and which detects cloudiness that occurs on the window surface due to the collision of the jet stream. An apparatus is disclosed in which the injection state is determined based on the imaging result. .

On the other hand, instead of these devices, it is possible to detect the injection status of a large number of nozzles individually and quickly, and regardless of the injection conditions such as the type of jet flow and the amount of injection,
A nozzle jetting state detection method has been proposed that can accurately determine whether the jetting state is good or bad.

This method consists of a jet flow detection plate placed opposite to the nozzle, an acoustic detection sensor attached to the other side of the detection plate, a measurement capsule that holds the front self-detection plate, and a detection plate that detects vibrations generated in the measurement capsule. an acoustic insulating plate that acoustically insulates the acoustic sensor; a signal processing device that processes the output signal of the acoustic detection sensor;
A method for detecting a jetting state of a nozzle by means of a device comprising: means for determining a jetting state of a nozzle based on an acoustic output signal after signal processing, the method comprising: This method converts the fuel into a low frequency signal based on the value, and compares the low frequency signal with the same value previously obtained under appropriate injection conditions to make a determination.

The acoustic detection sensor used in this method is generally
(Acoustic Emission) sensor, which detects high-frequency acoustic pulses generated in objects due to external stress and converts them into electrical signals corresponding to the magnitude of the acoustic pulses using the piezoelectric effect. The sensor is housed in a cylindrical sensor holder and fixed to a detection plate together with the holder.

In other words, in this method, the jet stream from the spray nozzle is
The nozzle collides with a detection plate placed opposite to the nozzle, and the sound generated inside the detection plate due to this collision is captured by an AE sensor attached to the other surface, and based on the output signal generated by the sensor due to the piezoelectric effect, The jetting condition of the nozzle is recognized and a judgment is made as to whether the nozzle is good or bad.

When using this method to detect the spray state of the spray nozzle in the secondary cooling zone of continuous casting equipment, it is necessary to move the detection plate together with the AE sensor in a state facing the jet stream from the spray nozzle. A method is adopted in which a measurement capsule incorporating an AE sensor, etc. is attached to a dummy bar, and the detection plate is moved together with the dummy bar, facing the jet stream from the spray nozzle.

Problems to be Solved by the Invention By the way, there are two methods for managing the AE sensor in the method for detecting the ejection state of a spray nozzle using the AE sensor: (I) an offline inspection method and (n) an online inspection method. There are two methods for offline testing of the AE sensor: ■ A method of passing a spray water flow rate through each sensor before incorporating it into a measurement capsule, and obtaining a calibration curve using the output signal for each flow rate. When inspecting the AE sensor after it has been installed, a method is used in which the detection plate of the AE sensor is rubbed or hit with a metal object to check for the presence or absence of an output signal.

However, methods ① and ③ require a lot of effort and time and are inefficient, and method ③ cannot maintain a constant output signal, and it is extremely difficult to check the sensors that are integrated. There is a drawback.

Furthermore, method (n) is a method in which the output of the AE sensor during measurement is compared with the output value during normal operation, the AE sensor that is considered to be defective is removed from the measurement capsule, and verified off-line. However, with this method, it is difficult to determine whether the cause is a clogged spray nozzle or a defective AE sensor based on the output from the AE sensor during measurement.
Another problem was that it took time to remove the AE sensor and verify it offline.

In addition, the detection plate to which the AE sensor is attached is fixed to the measurement capsule via an acoustic insulating plate such as anti-vibration rubber, but after long-term use, scale etc. may adhere to the detection plate and the acoustic insulating plate. As a result, accurate detection may not be possible due to vibrations of the measurement capsule or a decrease in detection ability, and an operator must periodically remove scales and the like that have adhered to the detection plate and its surroundings.

The purpose of this invention is to solve the above-mentioned problems in the injection state detection method using the AE sensor, and to accurately determine the quality of the AE sensor with a measurement capsule incorporating the AE sensor attached to a dummy bar. The purpose of this paper is to propose an inspection method for AE sensors that is capable of reducing the effects of scale attached to the detection plate, spray nozzle, etc.

Means for Solving the Problems The present invention provides a method for detecting the spray state of a spray nozzle by attaching a measuring capsule incorporating an AE sensor to a dummy paddle, in which a fluid ejecting device for the AE sensor is placed in a standby position of the measuring capsule. The gist of the invention is to compare the output signal of the acoustic detection sensor with a preset reference value using the fluid ejecting device to determine the quality.

The measurement capsule incorporating the AE sensor is attached to the dummy bar and moves within the roll cavity, and the jet stream from the spray nozzles arranged in parallel in the direction of movement of the dummy bar successively impinges on the surface of each detection plate. As a result, the acoustic pulse generated inside the detection plate is detected by the AE detection sensor.

When the measurement of the jet flow from the spray nozzle is completed, the dummy bar is pulled out from the roll cavity and waits at a predetermined location. Here, a fixed amount of fluid is sprayed to each AE sensor by the fluid injection device installed at the relevant position, and the AE sensor output signal at that time is stored as an initial value in, for example, a computer, and a preset reference value is set. Toko A
The output value of the AE sensor is compared with the output value of the AE sensor, and the quality of the AE sensor is determined based on the variation of the initial value with respect to the reference value.

Therefore, according to this method, without removing the measurement capsule incorporating the AE sensor from the dummy bar, the AE
It is possible to determine whether the sensor is good or bad.

In addition, by adjusting the pressure and flow rate of the fluid sprayed against the AE sensor, it is possible to easily remove scale, etc. attached to the periphery of the AE sensor.
It is possible to prevent a decrease in the detection ability of the sensor and to ensure detection accuracy.

The fluid injected from the injection device includes air, water, etc., but is not particularly limited as long as the detection ability of the AE sensor can be determined.

Embodiment FIG. 1 is a partially cutaway side view of the measuring capsule according to the invention, and FIG. 2 is a schematic diagram showing an example of the configuration of an apparatus for carrying out the method of the invention.

Here, a double-sided detection type in which AE sensors are attached to both the front and back sides of the measurement capsule will be explained as an example.

The measurement capsule has a plurality of detector mounting holes (2) corresponding to the positions of the spray nozzles, and a detection plate (3) and an AE sensor (4) are mounted to these mounting holes.

The detection plates (3) are arranged to face each other within the reach of the jet stream ejected from the spray nozzle, and an AE sensor (4) is attached to the other surface of the detection plates (3).

The detection plate (3) is made of a material whose material, thickness, size, etc. are selected according to the properties of the jet flow, such as the distribution width of the jet flow and the arrangement of the spray nozzles, and its - face is perpendicular to the jet flow. It is located in

This detection plate (3) is fixed to the acoustic insulation plate (5) with bolts, nuts, etc., and the acoustic insulation plate (5) is fixed to the fixed plate (
It is fixed to the measurement capsule (1) via bolts and nuts. That is, acoustic insulation is provided to prevent the vibration sound of the measurement capsule (1) from propagating to the detection plate (3). As an acoustic insulating board, for example, H350-10
Rubber of about 0 is suitable, but it is also possible to use cork or the like.

The AE sensor (4) is housed in a cylindrical sensor holder (9) and is fixed to the detection plate (3) together with the holder.

As shown in FIG. 2, the air injection device that injects air to each detection plate (3) has injection nozzles (7- 1), and an air supply piping system (8) that supplies air to the piping.
), a pressure control valve (8-2), a flow rate control valve (8-3), a pressure gauge (8-4), and a flow meter (8-5).

The air injection pipe (7) of this air injection device is connected to a dummy bar (
In the standby position of the dummy bar (not shown), it is installed at a position facing the front and back surfaces of the measurement capsule (1) attached to the dummy bar.

(10) is a waveform processing device that processes the output signal from the AE sensor (4) and performs waveform processing of the injection state of the jet flow of the air injection nozzle (7-1); (11) is a waveform processing device that processes the output signal from the AE sensor (4); a computer that stores the data and compares it with a reference value input from the setting device (12) to determine the quality of the AE sensor;
13) is a display device that displays the determination results.

The waveform processing device (10) that processes the output signal of the AE sensor (4) includes a preamplifier (10-1), a main amplifier (
10-2), a bandpass filter (10-3), a waveform processing section (10-4), and the like.

The output signal of the sensor is usually a weak signal of about 10 μV to 10 mV, so it is amplified to a processable level by a preamplifier (10-1) and a main amplifier (10-2), and then passed through a bandpass filter (10-3). Only a predetermined frequency band is extracted and manually stored in a computer (11) that determines the quality of the AE sensor (4).

When inspecting the AE sensor using the above device, use this A
When the E-sensor has finished inspecting the injection status of the spray nozzle in the secondary cooling zone, and the measurement capsule is pulled out together with the dummy bar and stopped at the predetermined standby position, the air injection device is turned on and air is injected from the air injection pipe (7). Each air detection plate (
3), and at the same time, each A to the computer (11).
Take in the output signal of the E sensor.

Note that the pressure and flow rate of the air to be injected are controlled by a pressure control valve (8-2) and a flow rate control valve (8-3), respectively.

Air injection is performed for a certain period of time, and the output values of each AE sensor during that time are stored in the computer (11), and the setting device (1
2) and the reference value set in advance according to A above.
The output value of the AE sensor is compared with the output value of the AE sensor, and if the measured value of the AE sensor matches or approximates the reference value, it is determined to be normal, and if it is not close, it is determined that the sensor is abnormal, and the determination result is It is displayed on the display device (13).

Figure 3 (aHb) and (c) illustrate the output values of the AE sensor when air is injected by the air injection device.
In both figures (a Hb ), the AE sensor output value has reached the reference value (50%), and in such a case, the AE sensor is determined to be normal. In contrast, in Figure (C), the AE sensor output value is significantly lower than the reference value, and in such a case, it is determined that there is an abnormality in the AE sensor.

On the other hand, if foreign matter such as scale is attached to the detection plate or its surroundings, the foreign matter is removed by blowing air onto the measurement capsule from the air injection pipe (7) with the measurement system of the AE sensor turned off.

Although it is desirable that the above-described AE sensor inspection be carried out each time continuous casting is completed, it may be carried out arbitrarily when the dummy bar is in the standby position.

As described in detail of the invention, according to the method of this invention, it is possible to perform an inspection with the AE sensor attached to the measurement capsule, and
The inspection is performed at the dummy bar standby position by spraying fluid such as air with a separate fluid injection device and comparing the output value of the AE sensor with the reference value, making it simple, quick and accurate.
It is possible to determine whether the sensor is good or bad.

Further, since foreign matter such as scale attached to the detection plate and its surroundings can be removed using the inspection fluid, the AE sensor can always be inspected in a normal state.

Further, the method of the present invention can be implemented with relatively simple equipment and can be easily attached to an existing dummy bar standby position, so it can be implemented without increasing equipment costs.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a partially cutaway side view of the measuring capsule of the present invention, Fig. 2 is a schematic diagram showing an example of the configuration of an apparatus for carrying out the method of the present invention, and Fig. 3 (a) (bHc) is the AE when air is injected from the air injection device of the same device as above.
This is an example of the output value of the sensor. 1...Measuring capsule 2...Detector mounting hole 3...Detection plate 4-...AE sensor 7
- Air injection pipe 8... Air supply piping system 10... Waveform processing device 11... Computer 12... Setting device 13... Display device

Claims (1)

[Claims] A cooling water jet flow detection plate placed opposite to the spray nozzle of the continuous casting machine, and a measurement capsule incorporating an acoustic detection sensor attached to the other side of the detection plate are attached to the dummy bar, and the output of the acoustic detection sensor is measured. In the method of determining the injection state of a spray nozzle based on a signal, a fluid injection device for the acoustic detection sensor is provided at a standby position of the measurement capsule, and the fluid injection device injects a certain amount of fluid to the acoustic detection sensor, A method for inspecting a spray nozzle abnormality detection sensor, characterized in that the output signal of the acoustic detection sensor at that time is compared with a preset reference value to determine pass/fail.