JP2638126B2 - Nozzle injection state detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for individually detecting the jet states of jets from a number of nozzles such as a cooling water nozzle in a continuous casting facility.

(Prior art)

In the continuous casting method, molten steel injected into a water-cooled mold having a cylindrical shape is cooled (primary cooling) by contact with the inner wall of the mold, and continuously drawn while being covered with a solidified shell on the outside.
In this method, cooling water sprayed by a large number of spray nozzles disposed below a mold is poured outward to further cool (secondary cooling) and continuously produce solidified slabs up to the inside. In this continuous casting method, in order to ensure the surface quality and the internal quality of the slab, it is necessary that the slab is appropriately cooled during the primary cooling and the secondary cooling.
In the process of the secondary cooling, while the cooling state of the slab depends on the state of spraying the cooling water from the spray nozzles, these spray nozzles are likely to be clogged by foreign substances mixed in the cooling water, Determining the quality of the injection state is an important issue for quality assurance of a slab.

Conventionally, a method generally performed for this determination is a method in which cooling water is injected from a spray nozzle during non-operation, and an operator visually observes the cooling water to determine the quality of the injection state. However, in this method,
There is a problem with the safety of workers exposed to the water jet,
In addition, the determination has to be subjective, there is a disadvantage that a high degree of skill is required for the observer,
Numerous rolls for guiding the slab are arranged at the position where the spray nozzle is arranged, workability is poor, and the number of arranged spray nozzles reaches several thousands, and observation of the spray state and The determination takes a lot of time, which is one of the factors that hinders the improvement of productivity in the continuous casting facility.

Therefore, conventionally, various devices that can detect the ejection state of the nozzle and determine the quality of the nozzle have been proposed.

For example, in this type of apparatus disclosed in Japanese Patent Application Laid-Open No. 58-202959, a pressure gauge and a flow meter are arranged in the middle of a supply pipe connected to a nozzle, and using these detected values, a predetermined arithmetic expression is used. The apparatus disclosed in Japanese Patent Application Laid-Open No. 61-249562 has a configuration in which the number of nozzles in a closed state is calculated. Accordingly, an image of a cloudy portion generated on the window surface is taken, and the ejection state is determined based on the result of the image pickup.

[Problems to be solved by the invention]

However, in the former, it is only possible to determine the number of nozzles in the closed state.For example, it is difficult to determine an abnormal injection state such as flash flood due to the dropping of the nozzle head, and it is also possible to specify the blocked nozzle. For this reason, after the determination is made, the identification must be performed by other means such as visual observation, and there is a drawback that much time and labor are required.
When this apparatus is applied to the determination of the injection state of a spray nozzle in a continuous casting facility, the number of nozzles installed is large. The resulting changes were small and difficult to discriminate. Such difficulties can be solved by installing the pressure gauge and the flow meter for each nozzle or every few nozzles, but a large number of pressure gauges and flow meters are required, and these daily accuracy is required. A great deal of work is required for management, and the configuration of a processing system that processes these detection results is also complicated and impractical.

On the other hand, when the latter device is used for determining the injection state of the spray nozzle in the continuous casting facility, the see-through window is formed on the side surface thereof, and a cylindrical body having an imaging device mounted therein is provided. While hanging from the top of the mold during non-operation, while moving in a state positioned between the rolls,
A method of sequentially imaging the cloudy state of the see-through window due to the jet flow from each spray nozzle is adopted, and it is possible to determine the jet state of each nozzle from the imaging result obtained in correspondence with the moving position of the cylinder, and blockage Nozzle identification may also be performed. However, in this device, the appearance of the cloudy portion changes depending on the state of opposition between the see-through window and the jet flow, so that the cylindrical body is always kept at a constant posture with respect to the jet flow. However, especially in the curved continuous casting equipment, it is practically impossible to maintain this posture, and it is difficult to accurately evaluate the injection state. In recent years, a spray nozzle that sprays cooling water in a mist shape is sometimes employed in order to make the state of spraying the cooling water uniform on the slab surface and to improve the cooling state. In this case, the see-through window is used. However, it is difficult to determine whether the ejection state is good or not from the imaging result because no local cloudy portion occurs in the image. Further, as described above, since the imaging is performed while inserting the cylinder between the rolls and moving the cylinder, even if the moving speed is increased, there is a limit in shortening the time required for detecting the injection state, During this time, the operation has been stopped, which has been a factor that hinders the improvement of productivity in the continuous casting facility.

The present invention has been made in view of such circumstances, and it is possible to detect the ejection states of a large number of nozzles individually and quickly, and furthermore, regardless of the type of jet and the injection conditions of the injection quantity body. In addition, an object of the present invention is to provide a nozzle ejection state detection device that can accurately determine the quality of an ejection state.

[Means for solving the problem]

The nozzle ejection state detection device according to the present invention includes a detection plate having one surface facing the jet from the nozzle, and the other surface of the detection plate being in contact with the detection plate. An acoustic detection sensor that detects the generated sound, and a determination unit that determines whether the ejection state of the nozzle is good based on an output signal of the acoustic detection sensor, and the determination unit includes: A value related to the ejection state of the nozzle is obtained from an output signal of the acoustic detection sensor, and the determination is performed by comparing the value with the same value obtained in advance under an appropriate ejection state. .

[Action]

In the present invention, the jet flow from the nozzle collides with one surface of a detection plate provided opposite thereto, and the sound generated inside the detection plate due to this collision is applied to an acoustic detection sensor provided in contact with the other surface. The ejection state of the nozzle is recognized based on the output signal generated by the sensor due to the piezoelectric effect, and the quality is determined.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. FIG. 1 is a schematic block diagram showing the configuration of a nozzle ejection state detecting device (hereinafter, referred to as the present device) according to the present invention.

In the figure, reference numeral 1 denotes a nozzle for detecting the injection state,
The apparatus of the present invention is arranged within the reach of the jet 2 jetted from the nozzle 1, the flat plate-shaped detection plate 3 having one surface facing the jet 2, and the other surface of the detection plate 3. An acoustic detection sensor 4, a signal processing device 5 that processes an output signal of the sensor 4 as described below, and determines an ejection state of the jet 2 from the nozzle 1, a display device 6 that displays a determination result, and the like. It becomes.

The detection plate 3, the distribution width of the jet 2, the jet amount, etc.
The material, the thickness and the size of which are selected according to the properties of the jet 2 are used, and one surface thereof is fixed so as to substantially face the jet 2. In FIG. 1, the detection plate 3 is fixed to the tips of the bar-shaped leg members 3a, 3a by nuts, but the method of fixing the detection plate 3 is not limited to this. The acoustic detection sensor 4 generally has an AE ( A co
ustic E mission) is what is referred to as a sensor, converting detected acoustic pulses of a high frequency band occurring in the object due to external stresses, due to the piezoelectric effect, the electric signal corresponding to the magnitude of the acoustic pulse Output.
It is housed in a cylindrical sensor holder 4a, and is firmly fixed to the other surface of the detection plate 3 to be detected. The acoustic detection sensor 4 may be directly fixed to the detection plate 3 by a means such as bonding without using the sensor holder 4a. However, the level of the detection accuracy of the sensor 4 depends on the detection surface thereof. Because it depends on the level of adhesion between the
At the time of fixing, it is important to improve adhesion by interposing grease and machine oil between the two.
When using the sensor holder 4a as shown in FIG.
An elastic member such as a spring is interposed between the bottom of the holder 4a and the acoustic detection sensor 4, and the detection surface is pressed against the detection plate 3 by the elastic restoring force of the member to improve the adhesion. It is possible.

That is, the apparatus of the present invention collides the jet 2 ejected from the nozzle 1 with one surface of the detection plate 3 and generates an acoustic pulse generated inside the detection plate 3 in accordance with the collision with the sound that closely adheres to the detection plate 3. To ensure that the detection plate sensor 4 catches it,
This is to determine the ejection state of the nozzle 1 based on the output signal of the sensor 4. The signal processing unit 5 that processes the output signal of the acoustic detection sensor 4 includes a preamplifier 10 and a main amplifier 1
1, a bandpass filter 12, a determination unit 13, and the like. The output signal of the acoustic detection sensor 4 is usually a weak signal of about 10 μV to 10 mV, which is first amplified by the preamplifier 10 and the main amplifier 11 to a level capable of performing the following processing. Only a predetermined frequency band is extracted by the filter 12 and input to the determination unit 13 for determining whether the injection state is good. The preamplifier 10 should be placed near the acoustic detection sensor 4 in order to suppress the attenuation of the output signal of the acoustic detection sensor 4 and remove the influence of the electrical noise superimposed on the signal on the detection result. ,this is,
It is also possible to be built in the sensor body or provided in the sensor holder 4a.

The determination unit 13 obtains, for example, an amplitude value of the output signal from the output signal of the acoustic detection sensor 4 as a value related to the ejection state of the nozzle 1, and determines the ejection state based on the amplitude value. In order to be able to make this determination, it is necessary that a sufficient correlation be established between the level of the output signal of the acoustic detection sensor 4 and the injection amount of the jet 2 from the nozzle 1. This correlation is established not only when the jet 2 is a normal jet but also when the jet 2 is in a mist shape. The mist-like jet 2 is provided with an air pipe 1a indicated by a two-dot chain line in FIG. 1, and is obtained by using a nozzle 1 that mixes air introduced from the air pipe 1a with a liquid and jets the liquid. FIG. 2 shows the result of examining the change in the amplitude of the output signal of the acoustic detection sensor 4 while gradually decreasing the injection amount using such a nozzle 1. It is clear from the figure that the above-mentioned correlation was established, and a sufficient correlation was obtained also in a similar experimental result (not shown) in a normal jet.

The determination unit 13 obtains, for example, a maximum value and a minimum value of the signal within a certain period of time from an output signal of the acoustic detection sensor 4 input to the preamplifier 10, the main amplifier 11, and the bandpass filter 12 and input thereto. The amplitude value is obtained by subtracting the latter from the former. It is desirable that the certain time is a section that moves continuously, that is, a section within a certain time from the present time.

FIG. 3 is a graph showing the relationship between the amount of injection from the nozzle 1 and the amplitude value when the jet 2 from the nozzle 1 is in an appropriate injection state. In the figure, the symbols △ and ▲ indicate the case where the jet 2 is a mist-shaped jet having a water-to-water ratio of 10, and the marks ○ and ● indicate the case where the jet 2 is a normal jet having a gas-to-water ratio of 0 , And the results of two measurements are shown. From this figure, it is clear that a good correlation and high reproducibility are obtained between the injection amount from the nozzle 1 and the amplitude value, regardless of the type of the jet 2. The determination unit 13 stores a curve indicating such a correlation for each type of the jet 2 in the form of an equation or a table approximating the curve. Then, the determination unit 13 determines whether or not the amplitude value obtained as described above for the jet 2 from the nozzle 1 to be detected is in the vicinity of the curve corresponding to the type and the jet flow of the jet 2. In the former case, it is determined that the injection state is appropriate, and in the latter case, it is determined that the nozzle 1 is in the closed state and a sufficient injection amount is not obtained,
The determination result is output to the display device 6, and the determination result is displayed on the display device 6.

Also, when the nozzle head of the nozzle 1 falls off and the jet 2 is in a flash flood state, the acoustic pulse generated inside the detection plate 3 due to the collision of the jet 2 is generated under an appropriate jet state. Have different frequency components for similarly generated acoustic pulses. Therefore, the output signal generated by the acoustic detection sensor 6 for such a flash flood-like jet 2 is almost completely cut off by the band-pass filter 12 of the signal processing device 5, and does not reach the determination unit 13. The amplitude value is substantially zero or an extremely small value, and the determination unit 13 determines that the injection state is inappropriate. The determination of the flash flood state is made by arranging a plurality of small-area detection plates 3 each having a separate acoustic detection sensor 4a in the distribution area of the jet 2, and using only a part of these acoustic detection sensors 4. When the sound pulse is detected and the detection by the other sound detection sensor 4 is not performed, it can be determined without using the band-pass filter 12 by determining that the flash is in a flash flood state. This is not a practical method because a large number of plates 3 and acoustic detection sensors 4 need to be installed.

When the apparatus of the present invention configured as described above is used for detecting the injection state of a large number of spray nozzles in a continuous casting facility, an acoustic detection sensor 4 having a detection plate 3 fixed thereto.
At the same time, it is necessary to move the spray nozzle while facing the jet flow from the spray nozzle. Such movement of the detection plate 3 can be realized by using a cylinder similar to that described in the above-mentioned JP-A-58-202959 and fixing the detection plate 3 to the side surface of the cylinder. In this case, as described above, it takes time to insert and move the cylindrical body between the rolls, and during this time, the operation must be stopped. The device of the present invention, like the device disclosed in JP-A-58-202959,
Since the imaging device and the optical system for guiding the cloudy image on the see-through window to the imaging device are not required, and only a fixed space for the detection plate 3 on which the acoustic detection sensor 4 is mounted is required, for example, casting At the start, a plurality of recesses are formed on the side surface of the dummy bar used as the pseudo bottom of the mold in correspondence with the arrangement position of the spray nozzle on one plane, and each of these recesses is provided with an acoustic detection sensor 4. The detection plate 3 is fixed in such a manner that the fixing surface of the detection bar 3 is set to the inside and the recess is closed, so that the detection plate 3 moves in response to the movement of the dummy bar in a mode in which the detection plate 3 faces the jet flow from the spray nozzle. It is possible to make a configuration. In such a case, when the dummy bar is introduced or pulled out each time casting is started, the jets from the spray nozzles arranged side by side in the moving direction are generated along with the movement of the dummy bar. It is possible to sequentially collide with the surface, and the acoustic detection sensor 4 detects an acoustic pulse generated inside the detection plate 3 due to these collisions. FIG. 4 is a graph showing a temporal change state of an output signal of the acoustic detection sensor 4 fixed to the detection plate 3 when a dummy bar having the detection plate 3 fixed to the side surface is introduced. . The vertical axis of the figure indicates not the raw output of the acoustic detection sensor 4 but the signal level after passing through the band-pass filter 12 of the signal processing unit 5, that is, immediately before being input to the determination unit 13. A in the figure is an output example in the case where the spray nozzle corresponding to the position is in a closed state and the ejection amount from the nozzle has not reached the predetermined ejection amount, and such a signal is given to the determination unit 13. In this case, the amplitude value obtained by the determination unit 13 also decreases, and this greatly deviates from the curve shown in FIG. 3, so that it is determined that the injection state is inappropriate. Also, B in the figure is an output example in the case where the nozzle head of the spray nozzle corresponding to the position is dropped and the jet flow from the nozzle is in a flash flood state. In this case, the sound detection sensor 4 emits a high-level signal. This output signal has a frequency band different from that in the case where the injection state is proper, and is mostly cut off by the band-pass filter 12, so that the signal reaching the determination unit 13 is obtained. Is extremely small as shown in the figure, and as a result of the above-mentioned count value becoming substantially 0, it is determined that the injection state is inappropriate.

In this way, the apparatus of the present invention can move the detection plate 3 in a state substantially facing the jet from the spray nozzle by fixing the detection plate 3 on the side surface of the dummy bar, and at the time of starting casting. Every time a necessary dummy bar is introduced or pulled out, it is possible to detect the ejection state of the spray nozzle and judge its quality based on the output signal of the acoustic detection sensor 4 fixed on the back side of the detection plate 3. On the other hand, it is not necessary to stop the operation for this detection, and the productivity in the continuous casting facility is greatly improved.

In the present embodiment, the maximum amplitude value of the output signal of the acoustic detection sensor 4 is used as the value related to the ejection state of the nozzle 1. For example, the number of peaks exceeding a predetermined level in the signal is counted. The configuration may be such that the injection state is determined using a count value obtained by weighting the result with energy.

Further, in the present embodiment, the case where the present invention apparatus is applied to detect the injection state of the spray nozzle constituting the secondary cooling zone of the continuous casting facility has been described, but the present invention apparatus is not limited to this. Needless to say, the present invention can be applied to any use for detecting the ejection state of the nozzle which is difficult to visually observe.

〔effect〕

As described in detail above, in the apparatus of the present invention, the detection plate is arranged with one surface facing the jet from the nozzle, and the simple configuration in which the acoustic detection sensor is simply fixed to the other surface of the detection plate has a simple structure. Regardless of the type, the detection of the ejection state can be accurately performed, and the quality of the ejection can be determined. In addition, by moving the detection plate by appropriate means, the detection of the ejection state of a large number of nozzles can be performed. However, when this is applied to the detection of the injection state of the spray nozzle of the continuous casting equipment, the detection plate is fixed to the side surface of the dummy bar, so that when the dummy bar is inserted or pulled out, Since the detection can be performed, it is not necessary to stop the operation for this detection, and the present invention has excellent effects such as a great improvement in productivity.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing the configuration of the apparatus of the present invention, FIG. 2 is a graph showing a change state of the output level of the acoustic detection sensor when the injection amount from the nozzle is variously changed, and FIG. 4 is a graph showing a correlation between an injection amount and an amplitude value in an appropriate injection state serving as a reference for determining an injection state;
FIG. 5 is a graph showing the temporal change of the output signal of the acoustic detection sensor when the apparatus of the present invention is used for detecting the injection state of the spray nozzle of the continuous casting facility. DESCRIPTION OF SYMBOLS 1 ... Nozzle, 2 ... Jet, 3 ... Detection plate 4 ... Sound detection sensor, 5 ... Signal processing device 6 ... Display device, 13 ... Judgment unit

Claims (2)

(57) [Claims] 1. A detection plate having a surface facing a jet from a nozzle, and a sound which is in contact with the other surface of the detection plate and detects sound generated on the detection plate due to the collision of the jet. A nozzle ejection state detection device, comprising: a detection sensor; and a determination unit that determines whether the ejection state of the nozzle is good or not based on an output signal of the acoustic detection sensor. 2. The method according to claim 1, wherein the determining unit obtains a value related to an ejection state of the nozzle from an output signal of the acoustic detection sensor,
2. The nozzle ejection state detection device according to claim 1, wherein the determination is made by comparing this with an equivalent value obtained in advance under an appropriate ejection state.