WO2002031445A1 - Method for measuring flow velocity of molten metal and its instrument, and measuring rod used for this - Google Patents

Abstract

A signal processing for determining the flow velocity of molten metal by measuring the vibration due to Karman vortex comprising a frequency component analyzing processing (A) of analyzing the frequency component of a measurement signal produced by a vibration sensing means that a measuring rod has, a first judgment (B1-B7) for extracting peaks that a peak envelope curve of the spectrum curve drawn by the processing (A) has and judging that vibration due to Karman vortex is present only if the difference or ratio between the maximum and minimum of the intensity of the spectrum among the peaks is over a predetermined value, a second judgment (C1-C4) for selecting only peaks having a spectrum intensity of over a predetermined ratio with respect to the peak having the maximum spectrum intensity from among the extracted peaks if vibration due to karman vortex is judged to be present and selecting the peak having the maximum frequency, and flow velocity calculation (D) for calculating the flow velocity of the molten metal by using the frequency.

Description

 Description Method and apparatus for measuring flow velocity of molten metal and sensing rod used for the method

 The present invention relates to an apparatus and a method for measuring the flow rate of molten metal such as molten steel, and more particularly to a continuous production facility, in which the flow rate of molten metal such as molten steel injected into a mold from a tundish through an immersion nozzle is continuously measured. The present invention relates to a flow velocity measuring device and a method for directly measuring the flow velocity. Background art

 In the process of continuous production of molten steel, there is a process of distributing and injecting molten steel from a tundish to a mold through an immersion nozzle. The immersion nozzle is provided with a plurality of discharge ports, and is configured to discharge the same amount of molten steel from the plurality of discharge ports. Then, the molten steel discharged from the immersion nozzle is supplied while being controlled so that the interface height in the mold is maintained at almost the same level, and the molten steel filled in the mold is cooled by removing heat from the mold. By solidifying and continuously pulling out from the lower side, it is possible to obtain animals continuously.

 By the way, some problems have been pointed out with respect to injection of molten steel into the mold by such a submerged nozzle. For example, if the immersion nozzle is used for a long time, the discharge rate of molten steel flowing out from each discharge port will be uneven. This is because the aluminum added in the molten steel for the purpose of deoxidation is oxidized to become alumina, which adheres and deposits on the inner wall of the immersion nozzle, closes the immersion nozzle, and allows the molten steel in the immersion nozzle to flow smoothly. This is to inhibit. As a result, the discharge amount of the molten steel injected into the mold is deviated due to the direction, causing non-uniform solidification in the mold and disturbance of the molten steel surface, thereby lowering the quality of the material and reducing the productivity. Causes a decline.

In order to avoid such a situation, it is important to detect the bias of the discharge flow ejected from the immersion nozzle at an early stage and take measures to prevent this. Therefore, various methods for detecting the bias of the discharge flow have been conventionally proposed. For example, [1] a method of monitoring uneven temperature rise of mold cooling water and presuming that there is an uneven discharge flow when this is observed, [2] a method of monitoring multiple positions in the mold In this method, the fluctuations in the molten steel surface level are continuously measured, and when the difference is observed, it is estimated that there is an uneven discharge flow.

 However, each of these methods is an indirect measurement method, and the response is slow, the measurement result cannot be quantitatively evaluated, and the measurement result cannot be used for the feedback control of the peripheral device. For example, when non-uniform discharge is detected, the electromagnetic brake in the mold is operated to individually control the discharge amount from each discharge port. Since the detection method cannot quantitatively measure the drift, the data of the drift detection cannot be used directly for controlling the electromagnetic brake, and these controls must rely on the experience and intuition of field workers as before. Absent. When the drift is detected, it is ideal to immediately take measures such as increasing the power of the electromagnetic brake in the mold, increasing the flushing gas volume in the immersion nozzle, increasing the temperature of the molten steel in the tundish, or replacing the immersion nozzle. However, the conventional drift detection method has a problem in that the response is slow and countermeasures tend to be delayed, and the drift is further increased.

 In order to solve such problems, the present inventors have already proposed the techniques described in Patent Nos. 2 842 158 and 2 894 272. This is a method that employs a direct method, while the conventional drift detection method uses an indirect method as described above.

The contents are as follows: a detection rod made of a heat-resistant material rod equipped with vibration detection means is immersed into molten steel so as to block the discharge flow of molten steel from the immersion nozzle of the mold. Because of the presence of, the vibration of the detection rod caused by the Karman vortex generated downstream of the detection rod is detected by the vibration detection means as a continuous signal, and this detection signal is subjected to high-speed Fourier transform (hereinafter referred to as FFT). In the obtained spectrum curve, the flow velocity of the above discharge flow is calculated from the relational expression between the frequency of the spectrum component having the maximum spectrum intensity and the flow velocity of the molten steel. is there. According to this technique, the flow rate of molten steel in a mold is measured by direct means. As a result, it was possible to detect signs of drift early and take preventive measures. In addition, since the degree of drift can be quantitatively measured, the measurement result is fed back to the control unit of peripheral devices such as an electromagnetic brake, immersion nozzle flushing gas ejection device, and tundish heater, and the drift is measured. It has become possible to take active measures to solve the problem, and as a result, it has become possible to automate the operation of distributing and injecting molten steel into the mold.

 The earlier invention by the present inventors seems to be the best technique at the present time as a method for directly measuring the flow velocity of molten steel. However, it is improved in the signal processing by FFT processing, the subsequent spectrum judgment processing, and the sharp discrimination of the frequency used in the calculation of the molten steel flow velocity, which is performed in the process of obtaining the molten steel flow velocity from the detection signal detected by the vibration detection means. There is a point to be left. It is as follows.

 [1] Ensuring distinction of useful spectral components after FFT processing

 In the process of obtaining the flow velocity of molten steel from the detection signal detected by the vibration detection means, the detection signal is subjected to FFT processing to obtain a spectrum curve. This spectrum force shows various forms because the flow state of molten steel in the mold is very complicated and changes every moment even in the short time of the FFT processing time. The issue is how to distinguish useful spectral components from the spectrum cabs that exhibit such various forms.

 [2] Removal of noise components other than Karman vortices

 When measuring the flow velocity of molten steel, the frequency of vibration generated by factors other than Karman vortices, such as the inherent vibration of the mold called mold oscillation, the intrinsic vibration of the probe itself that holds the sensing rod or the gantry itself that holds the probe, etc. Appears in the spectrum club. For this reason, the conventional simple logic that calculates the flow velocity using the frequency of the spectral component that indicates the treetop spectral intensity within the frequency band to be detected by the probe is generated by factors other than the Karman vortex. The frequency of the vibration may be used to calculate the flow velocity. The problem is how to avoid the case where the true velocity value of molten steel cannot be obtained due to such a situation.

 C 3] Improving measurement accuracy and reducing processing time

Detection signal sampling-FFT processing-Flow rate calculation processing patch In the method performed by processing, the processing requires time, and the obtained flow velocity value lacks real-time performance, and it cannot be said that the flow velocity value follows the complicated flow state of molten steel in the mold. On the other hand, if the number of samplings is reduced to shorten the processing time, the frequency resolution of the spectrum curve is degraded, and the measurement accuracy is degraded. The problem is how to improve the measurement accuracy and shorten the processing time. The above are points to be improved with respect to the signal processing and the spectrum determination processing. In addition, there are the following points to be improved with respect to the measurement of the flow velocity of molten steel.

 [4] Automation of probe operation

 The probe operation is an operation in which the detection rod is immersed in a predetermined position in the molten metal and returns to its original state after the measurement is completed. Conventionally, this probe operation was carried out in such a way that the gantry to which the probe was attached was attached to the surrounding fixed equipment while the operator held it in a narrow space, and was removed after the measurement was completed. Therefore, workability was poor and there was a problem in terms of safety. In addition, the positioning of the measured position in the mold or the orientation of the mounting surface of the vibration detection means 設 the setting of the immersion depth of the detection rod, etc. are performed manually by the operator when the probe is mounted on the gantry. Therefore, accuracy and workability were poor.

 [5] Handling handheld measurements

 For temporary and simple measurements in a short time, it is convenient to hold the pedestal with the probe by hand, but the pedestal is likely to vibrate, which is likely to be an error factor in flow velocity measurement. . Also, when mounting the probe, the workability was poor because the conventional device had to visually adjust the direction of the mounting surface of the vibration detection means to fix the probe. As a result, the mounting was likely to be incomplete, and the probe could fall into the mold during measurement. Also, the workability during removal was poor.

 [6] Improvement of erosion resistance of detection rod

Conventionally, a ceramic protection tube such as Sialon or Mo—Zr〇2 cermet is used for the detection rod. For this reason, when the detection rod came into contact with the meniscus layer formed between the mold powder molten layer and the molten steel, the contact portion of the detection rod was severely eroded, and measurement could not be performed for a long time. The present invention has been made in view of such a situation. The purpose is to detect the vibration caused by Karman vortex using a detection rod equipped with vibration detection means, and to inherit the above-mentioned technology for obtaining the flow velocity of molten steel, To provide a method and apparatus for measuring the flow velocity of molten steel, which aims to ensure the distinction of the vector components, remove noise components other than those caused by Karman vortices, and solve the problems of improving measurement accuracy and reducing processing time. It is something to try. In addition, it proposes a probe holding structure and automation of probe operation, measures for hand-held measurement, and measures to improve the erosion resistance of the sensing rod. Disclosure of the invention

 The present inventors have earnestly studied to solve the above problems, and as a result, have obtained the following recognition regarding signal processing and spectrum determination processing. This recognition applies not only to molten steel, but also to molten metal in general, and hence will be applied to molten metal.

 The flow of molten metal in the mold varies. Sometimes a strong unidirectional flow exists. Alternatively, there are cases where multiple weak flows exist in a mixed state and interact with each other to create a complicated flow situation, or the flow almost disappears and stagnates.

 In the former case, since a protruding peak appears on a spectrum curve obtained by performing FFT processing on the detection signal, it is relatively easy to distinguish spectral components caused by Karman vortices. However, in the latter case, peaks having the same level of output are inconsistent, or almost no peaks are observed.Therefore, it cannot be said that there is a spectral component caused by the Karman vortex. In such a case, the calculation of the flow rate of the molten metal should be excluded from the calculation.

 Therefore, based on such recognition, the following determination procedure was performed to determine the frequency of vibration caused by the Lehman vortex from the detection signal obtained by the vibration detection means.

First, a frequency component analysis process for analyzing the frequency components of the continuous detection signal obtained by the vibration detection means provided on the detection rod is performed. Specifically, FFT processing of the detection signal is performed. Any other method that analyzes frequency components Is also good. This is referred to as frequency component analysis processing, and the means for executing the processing is referred to as frequency component analysis means.

 Next, a plurality of peaks in a peak envelope curve obtained by connecting adjacent peaks of the spectrum curve obtained from the frequency component analysis processing are extracted, and among these peaks, a peak having the largest spectrum intensity is extracted. Only when the difference between the minimum and the minimum is greater than or equal to a certain value, the existence of vibrations caused by Karman vortices is recognized. Otherwise, it is judged that there is no vibration caused by Karman vortices. Here, the disparity between the maximum and the minimum may be expressed by an absolute value, or may be expressed by the ratio of the minimum to the maximum. This determination is referred to as a first determination, and a unit that performs this determination is referred to as a first determination unit.

 Next, when the existence of the vibration caused by the Karman vortex is recognized by the first determination means,

From among a plurality of extracted peaks, only peaks having a spectral intensity equal to or higher than a certain ratio are selected from peaks having the highest spectral intensity, and peaks having the highest frequency are distinguished from the peaks. This is referred to as a second determination, and a means for executing the determination is referred to as a second determination means.

 Then, the flow velocity of the molten metal is calculated using the frequency having the peak that is distinguished in the second determination. This is referred to as a flow velocity calculation, and the means for executing this is referred to as a flow velocity calculation means.

In the above first determination, if the difference between the maximum and minimum spectral intensities is smaller than a certain value, it is determined that there is no vibration caused by the Karman vortex, and the measured value at this time is By excluding the calculation target of the flow velocity measurement, when the Karman vortex is not generated, the erroneous determination that the high frequency vibration due to the waving of the molten metal is the vibration due to the Karman vortex is prevented. Further, in the above-mentioned second determination, it is a disturbance factor when a plurality of Karman vortex vibrations occur that the peak having the highest frequency is distinguished and the frequency of the peak is used for calculating the flow velocity of the molten metal. This is because the maximum flow velocity is obtained by removing the frequency of the vibration having the maximum amplitude intensity. The maximum flow velocity is determined by factors such as uneven solidification of the molten steel in the mold and disturbance of the molten steel surface, as well as a decrease in material quality and a reduction in the production efficiency. Because it is based on. Detecting the direction of flow of the molten metal is very effective for detecting signs of drift of the molten metal in the mold. Therefore, the direction of the flow of the molten metal is detected using the following means. First, vibration detection means is used in which the level of the signal obtained differs depending on the direction of the detection rod with respect to the flow of the molten metal when the detection rod is immersed. In addition, a rotation means for changing the direction of the detection rod by rotating it around its axis and a rotation angle detection means for detecting the angle of rotation are used. Then, the detecting rod is rotated by the rotating means, and when the maximum peak of the spectrum intensity extracted by the above-mentioned first determining means is maximized, the molten metal is detected from the rotating angle detected by the rotating angle detecting means. The direction of the flow. By using such a molten metal flow direction detecting means, the flow direction of the molten metal can be known.

 When FFT processing is used to analyze the frequency component of the detection signal obtained by the above-described vibration detection means, a fast Fourier transform frame (hereinafter, referred to as an FFT frame), which is data to be processed for FFT processing, is as follows. It is recommended to be formed with

 That is, a block is formed by a data train obtained by continuously sampling the detection signal within a unit time. A predetermined number of these blocks are successively combined in the order of formation to form an FFT frame. The latest FFT frame composed of these blocks is formed as follows. That is, each time the latest block is formed, the block is inserted at the beginning of the last FFT frame formed, the subsequent blocks are sequentially shifted, and the last block is discarded, so that the latest block is discarded. Form a frame. This process is repeated every time the latest block is formed. In this way, a large number of blocks can be used to form an FFT frame, which is a processing data to be subjected to the fast Fourier transform, with a short response time, so that the frequency of the spectrum curve obtained by the FFT processing can be obtained. The resolution can be increased, and the responsiveness and accuracy of the flow velocity measurement can be improved.

The present invention also proposes automation of probe operation. Here, the probe operation is, as described above, an operation in which the detection rod is immersed in a predetermined position in the molten metal, and is returned to the original state after the measurement is completed. The probe is a detection rod and it is stored. This is a concept including a holding unit to be held. Probes come in a variety of forms and are sensing rods. In some, the detection rod is detachable from the holder. The following explanation is based on the latter, but does not exclude the former. Further, the form of the holding section is not limited to a specific one.

 Probe operation can be fully automatic, semi-automatic, or fully manual.

 For example, when the molten metal flow velocity measuring apparatus of the present invention is provided with a manipulator capable of performing a probe operation fully automatically, it is recommended that this manipulator be configured as follows.

 In other words, a probe that stands vertically and a probe that holds the detection rod so that the base end is suspended from the top of the post and the rod-shaped detection rod is parallel to the upper opening surface of the mold. An arm attached to the tip, a turning means for turning the arm horizontally, and a middle part of the arm so that the detection rod is vertically upright with the tip end downward with respect to the upper opening surface of the mold. Bending / extending means for bending or stretching the arm with the joint provided as a fulcrum, and for moving the tip of the detection rod up and down when the detection rod is in an upright state. This is a fully automatic manipulator having a vertical moving means for immersing the detection rod in the molten metal in the mold and withdrawing the detection rod. In this way, the detection rod can be immersed in and out of the molten metal in the mold.

 The above fully automatic manipulator may be provided with a telescopic means for extending and contracting the arm in the axial direction. In this way, when the measurement is not performed, the manipulator can be prevented from obstructing other operations by contracting the arm.

 The above-mentioned fully automatic manipulator may be provided with horizontal moving means for horizontally moving the support column in the long side direction of the mold. By doing so, the detection rod can be moved over a wider range.

The above-mentioned fully automatic manipulator may be provided with a means for detecting the level of the molten metal in the mold and a control means for controlling the vertical movement means based on information output from the level detecting means. Good. In this way, the inspection The control to accurately immerse the shiver in the immersion position can be automated using the up and down movement means.

 The above-mentioned fully automatic manipulator may be provided with attaching / detaching means for automatically attaching / detaching the probe holding the detection rod. By doing so, the attachment and detachment of the probe to and from the manifold can be automated. Therefore, it is possible to automate the replacement of the exhausted detection rod, and to more fully automate the measurement operation.

 When the above-mentioned fully automatic manipulator has a turning device, a bending and extending device, a vertical moving device, and a telescopic device, a horizontal moving device, and a detachable device, the manipulator comprehensively controls these devices. Means may be provided. As a result, it is possible to automate the process from mounting the probe to moving to the measurement location, further immersing the detection rod in the molten metal of the mold, pulling up and retreating the probe at the end of measurement, and removing the probe. .

 It is also conceivable to perform the probe operation semi-automatically. As an example of a manipulator that adopts this method, a horizontal moving means having a moving body that moves forward and backward by projecting or retreating above the upper opening of the mold, and one end pivotally connected to the moving body are used. At the other end of the cam, the other end of which tilts in an up and down arc along the direction of movement, as a rotation fulcrum, a probe is installed so that the tip of the detection rod held by the probe is at the bottom. There is a semi-automatic manipulator having a tilting means.

 It is also conceivable to immerse the detection rods manually. A manipulator that adopts this method is a erection rod that is horizontally mounted on the upper surface opening of the mold, one end of which is a rotation fulcrum, and the other end is tilted in an up and down arc. On the way, there is a manipulator having a construction rod in which the probe is slidably suspended in the axial direction of the construction rod so that the tip of the detection rod held by the probe is directed downward.

Although the manipulator described above is used as a fixed facility, the present invention also proposes a hand-held manipulator for simple measurement. This manipulator has a pedestal on which a detection rod having vibration detecting means is attached, and an accelerometer attached to the pedestal. The operator uses the pedestal while holding it by hand. It is a manipulator. For the measurement using this manipulator, it is necessary to use a discriminating means for discriminating the vibration of the gantry captured by the accelerometer from the vibration detected by the vibration detecting means. By using this manipulator, it is possible to eliminate the influence of the vibration of the gantry, which causes an error in the flow velocity measurement.

 In the above manipulator, the measurement of the flow velocity at a specific measurement depth position is performed by adjusting the immersion depth of the detection rod.In this measurement, the entire part of the detection rod immersed in the molten metal is measured. Since it is a measurement site, it cannot be determined at which depth position the detected vibration mainly occurs. However, by devising the shape of the sensing rod in the longitudinal direction, the main object of measurement is to be within a certain range of the tip of the sensing rod at the specified depth where the sensing rod is immersed. Can be measured. In other words, the cross-sectional shape of the detection rod other than the tip for measuring the flow velocity is shaped so that the occurrence of Karman vortices is suppressed as compared with the tip, and by using such a detection rod, the molten metal The generation of Karman vortices at a depth position halfway from the surface to the depth position where the flow velocity is to be measured can be suppressed as much as possible. Therefore, by immersing the detection rod having such a shape at a specific depth position, the tip is kept at a specific depth position in the molten metal, and the detection rod is generated at this specific depth position. It is possible to measure the flow velocity based on the vibration mainly caused by Karman vortex.

The following is considered for improving the erosion resistance of the detection rod. In order to increase the erosion resistance of the sensing rod, it is necessary to minimize contact with the meniscus layer formed between the molten metal and the molten powder floating on the surface. This is because the meniscus layer is considered to be the largest cause of localized erosion. As a result of the study, the present inventor found that in order to suppress the contact with the meniscus layer, a material having good wettability with the molten powder was previously present on the surface of the detection rod, and an opportunity for the molten powder to cover the surface of the detection rod was obtained. It was concluded that reducing the contact with the interface by maximizing the value was as effective as possible. Based on this conclusion, the proposed sensing rod is 500 β π !, made of either zirconia, silica zirconia or calcium zirconia on the surface. One provided with a coating layer having a thickness of up to 150 m. Also, what actually requires erosion resistance is the part located in the meniscus layer when the sensing rod is immersed in the molten metal. Therefore, the surface of at least this area of the sensing rod should be covered with a sleeve made of one of zirconia, siligate zirconia, or calcium zirconia, which has excellent erosion resistance. You may. BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a flowchart showing an outline of a procedure of signal processing and determination. FIG. 2 is a flowchart showing details of the signal processing and determination procedure. FIG. 3 is an explanatory diagram showing the concept of FFT processing.

 FIG. 4 is a graph showing an example of a spectrum curve.

 FIG. 5 is a graph showing a peak envelope curve in the graph of FIG.

 FIG. 6 is a graph showing the peaks of the peak envelope curve of FIG. FIG. 7 is a graph showing an example of a peak envelope curve when there is no vibration caused by Karman vortex.

 FIG. 8 is a graph showing an example of a peak envelope curve when there is no vibration caused by Karman vortex.

 FIG. 9 is an explanatory diagram showing the relationship between the throughput and the flow velocity.

 FIG. 10 is an external view of an example of a fully automatic manipulator.

 FIG. 11 is an explanatory view showing the movement of the support and the arm of the manipulator. FIG. 12 is an explanatory view showing the operation of another example of a fully automatic manipulator. Fig. 13 (a) is an external view of an example of a detection rod that minimizes the occurrence of Karman vortices on the shaft, and (b) is a configuration in which the detection rod of (a) is immersed in molten steel. It is clear.

 FIG. 14 is an illustration showing a state in which a detection rod having a triangular prism tip is immersed in molten steel.

FIG. 15 is an external view of an example of a probe having a function of detecting a flow direction of molten steel. FIGS. 16 (a) and (b) are illustrations when the detection rod of FIG. 15 is immersed in molten steel.

 FIGS. 17 (a) and 17 (b) are explanatory views showing a semi-automatic manipulator, in which (a) is an explanatory view showing a state where a probe is lifted, and (b) is an explanatory view showing a state where a probe is immersed in molten steel.

 FIG. 18 is an explanatory diagram showing a manual manipulator.

 FIG. 19 is a perspective view showing an outline of a hand-held manipulator.

 FIG. 20 is an explanatory view showing a hand-held manipulator and a state in which a probe is mounted on a gantry.

 FIG. 21 is an explanatory view showing how an operator handles a hand-held manipulator.

 FIG. 22 is an illustration of a case where a detection rod using a sleeve made of a material having high erosion resistance is immersed in molten steel.

 FIG. 23 is an explanatory diagram showing a flow state of molten steel in a mold.

 FIG. 24 is an explanatory diagram showing an example of the screen of the monitoring panel. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention relates to a method for directly measuring the flow velocity of molten metal from the vibration of a detection rod caused by a Karman vortex, and a signal processing by FFT processing performed in a process of calculating a flow velocity from a detection signal obtained by detecting the vibration of the detection rod. The most distinctive feature is that the content of the spectrum determination process after that and the contents of the process have been devised. We also propose a probe holding structure for this measurement and automation of probe operation. Further, a preferred embodiment of the detection rod mounted on the probe is also proposed. In the following description, molten steel is taken as molten metal, but application to molten metal other than molten steel is not excluded. The present invention goes through a processing procedure as shown in FIG. These are the frequency component analysis processing A, the first judgment B, and the second judgment (:, flow velocity calculation D. FIG. 2 shows the contents of the first judgment B and the second judgment C in more detail. Hereinafter, the contents of each process will be described. Frequency component analysis> (A in Fig. 2)

 This is a process of analyzing a frequency component included in a detection signal continuously output from a vibration detection means such as a strain gauge provided on the detection rod. This processing is performed by FFT processing. In order to increase the frequency resolution of the spectrum curve obtained by the FFT processing, it is necessary to increase the amount of data to be processed for fast Fourier transform. However, simply increasing the number of collected data lengthens the measurement period and reduces the responsiveness of the flow velocity measurement. Therefore, in order to secure a large amount of data to be processed and not to reduce the responsiveness, we adopted a method that can secure a large number of data to be processed even with the same number of collected data. The FFT processing using this method is a method named the moving block FFT calculation processing method by the present inventor, and has processing contents as shown in FIG. In this processing, the formation of the FFT frame, which is the data to be processed to be used for the FFT processing, is performed as follows.

 That is, a block is formed from a data sequence obtained by continuously sampling the detection signal at a fixed sampling period, that is, within a fixed unit time. A predetermined number of these blocks are successively combined in the order of formation to form an FFT frame. The latest FFT frame composed of these blocks is formed as follows. That is, each time the latest block is formed, the block is inserted at the beginning of the last FFT frame formed, the subsequent blocks are sequentially shifted, and the last block is discarded, so that the latest FFT frame is discarded. Form. This process is repeated every time the latest block is formed.

 <First judgment> (B1 to B7 in Fig. 2)

This determination is to determine whether or not a prominent peak exists in the peak envelope force curve obtained from the spectrum curve obtained by the frequency component analysis processing by the FFT processing. is there. If there is a prominent peak, it is determined that there is a vibration component due to the Karman vortex, and the process proceeds to the next process.If there is no prominent peak, the FFT frame is used in this FFT frame. It is assumed that there is no vibration component caused by Karman vortex within the unit time of sampling of the detection signal performed to form the first block that constitutes The measurement result within this unit time is processed so as to be excluded from the calculation target for the flow velocity measurement.

 Specifically, as shown in Fig. 8, the peak envelope carp has a high output even when there are continuous low-level peaks, and as shown in Fig. 7, even when there is a high output peak. If the peaks are continuous (a, b, c, d-), it is assumed that there are no outstanding peaks, and the spectral cavities within this unit time are excluded from the calculation for flow velocity measurement. In the latter case, it is presumed that strong disturbance factors such as mold oscillation exist. On the other hand, in the former case, it is presumed that there is no flow, or that multiple vibrations cancel each other out and no distinctive peak exists. In order to exclude these from the calculation target, it is determined whether the difference between the maximum and the minimum in the peak intensity curve among the multiple peaks in the peak envelope curve is equal to or greater than a certain value, and the difference is constant. Only when the value is greater than or equal to the value, the existence of vibration due to Karman vortex is recognized, and otherwise, it is determined that there is no vibration due to forceman vortex.

This process specifically follows the following procedure. First, if the spectrum curve obtained by performing the FFT processing on the FFT frame formed of the data sequence obtained by sampling the detection signal within a certain unit time is as shown in FIG. 4, FIG. As shown, the peaks of this spectral curve are connected by an envelope to create a peak envelope force curve (B1). Next, as shown in FIG. 6, peaks P1 to P10 in the peak envelope curve are extracted (B2). Then, from the extracted peaks, for example, a difference Δ ピ ー ク between a peak (Pmax) and a minimum peak (Pmin) having the maximum spectrum intensity, such as P2 and P9 in FIG. 6, is calculated. Judge whether or not it is over a certain value. Whether the difference ΔΡ is equal to or greater than a certain value may be determined by determining whether PminZPmax is equal to or less than a certain ratio (B3, B4, B5). In FIG. 2, NN% described as “spectral intensity reference ratio NN%” (B4) corresponds to this P min / P max. If the difference between them is equal to or greater than a constant value P or P min / P max is less than NN%, it is determined that there is a vibration caused by Karman vortex (B 6), and the difference or PminZ Pmax equal to or less than a constant value ΔΡ is determined. If exceeds NN%, it is determined that there is no Karman vortex-induced vibration ( B 7).

 <2nd judgment> (C1 to C4 in Fig. 2)

 This determination is based on the fact that, when the presence of vibrations caused by Karman vortices is confirmed in the first determination (C 1), a certain peak is determined for the peak showing the maximum spectral intensity from among the multiple peaks. A peak having a spectral intensity equal to or higher than the ratio is selected (C2, C3), and a peak having the highest frequency is distinguished among them (C4). The “spectral intensity reference ratio N%” (C 2) in FIG. 2 is a reference ratio used for selecting a peak having a spectrum intensity equal to or higher than a certain ratio. For example, in FIG. 6, suppose that peaks P1, P3, and P4 having a certain ratio or more of the spectrum intensity with respect to the peak P2 showing the maximum spectrum intensity are as follows. Choose the P4 with the highest frequency in. Here, the peak with the highest frequency is selected to find the maximum flow velocity. The maximum flow velocity is determined based on the maximum flow velocity and its fluctuations.The factors that cause uneven solidification of the molten steel in the mold, turbulence of the molten steel surface, and cause a decrease in material quality and a decrease in production efficiency. Because.

 <Flow velocity calculation> (D in Fig. 2)

 The maximum flow velocity of the molten metal is calculated using the frequency having the peak that is distinguished in the second determination.

 As described above, through the first judgment and the second judgment, various kinds of factors such as removal of the frequency of the vibration having the maximum amplitude intensity, which is a disturbance factor when a plurality of Karman vortex vibrations occur, are removed. The maximum flow velocity can be obtained by removing the disturbance due to high-frequency vibrations and the like.

 It is preferable that disturbance factors other than the above are also removed in advance. For example, since the frequency of the mold oscillation and the natural frequency of the probe are information that can be obtained in advance, they are input to the device that performs the FFT processing before measurement, and are automatically performed during the FFT processing. It is desirable that peaks within the frequency proximity range be excluded from the judgment.

Since mold oscillation can be calculated from operation information such as manufacturing speed, it is also good to always obtain this information from an operation computer or the like and exclude it from the judgment. Good. It is preferable that the mold oscillation is simultaneously recorded on a recording device together with some other operating conditions so as to be a material that can be examined in detail later. The flow velocity calculation is performed using the fact that the frequency number f of the Karman vortex vibration is correlated with the flow velocity V of the molten steel discharge flow and the diameter D of the detection rod. These correlations can be expressed as a relational expression of S = (fD / V). Here, S is a constant that does not depend on the type of molten metal. Fig. 9 shows the result of examining the relationship between the maximum flow velocity of the molten steel discharge flow in the mold obtained by such a method and the throughput of molten steel from the immersion nozzle (the amount of molten steel supply). According to this figure, when the throughput is large, the change over time in the flow velocity is large, and the flow velocity value is generally high. It is important to control the amount of throughput while recognizing such a situation.

 The above is a device in the signal processing of the detection signal and the determination thereof. These methods detect and analyze vibrations caused by Karman vortices that occur downstream of a detection rod that is crushed so as to block the flow of molten steel. The present invention can be applied without being limited to the form of the rod or the form of the vibration detecting means. For example, as a vibration detecting means, there is a method using optical means other than using a strain gauge.

 Next, the probe operation required for performing the measurement will be described. First, it is important for probe operation to ensure that Karman vortices are generated, and to generate stronger Karman vortices and detect their vibrations more strongly. For this purpose, it is necessary to immerse the detection rod in a predetermined position and in a certain posture.However, conventionally, in a site with a poor scaffolding, the operator puts the detection rod in the narrow working space between the mold and the tundish. The work was not only difficult, but also involved the danger of the work. Therefore, the present invention proposes an automated probe operation as a method for solving this problem.

FIGS. 10 and 11 show a fully automatic manipulator. In FIGS. 10 and 11, the manipulator 1 is provided near the outer wall on both short sides of the mold 2. In the actual measurement, the mold 2 is covered with a mold cover, but this is omitted in the description of this specification. This manipulator 1 is composed of a column 7 and an arm 6. A probe 8 holding a detection rod 9 is attached to a tip of the arm 6. The hollow pipe fixed to the base end of the arm 6 is rotatably fitted near the top of the column 7, so that the arm 6 can pivot horizontally around the column 7. I have. The arm 6 is provided with a joint 12 in the middle thereof, the base end of the arm 6 is composed of a rear outer pipe 6b and a rear inner pipe 6a, and the distal end of the arm 6 is a front end. It comprises an outer pipe 11 and a front inner pipe 10. The rear inner pipe 6a is slidably fitted in the axial direction of the arm 6 inside the rear outer pipe 6b provided on the base end side of the arm 6, so that the arm 6 moves in the axial direction. Can be expanded and contracted. Further, the distal end side of the arm 6 can be bent by the joint portion 12 provided on the arm 6 so that the distal end faces downward. Further, by moving the hollow pipe fixed to the base end of the arm 6 up and down along the column 7, the entire arm 6 can be moved up and down.

When the fully-automatic manipulator 1 is not used, the arm 6 is retracted from the upper opening surface of the mold 2 so as not to hinder other operations. At the time of measurement, the arm 6 is turned or extended to bring the probe 8 attached to the tip of the arm 6 close to the discharge port of the immersion nozzle 100 in the mold 2. Then, the tip side of the arm 6 is bent and erected, the detection rod 9 held by the probe 8 is kept vertical to the upper opening surface of the mold 2, and the entire arm 6 is moved downward to perform detection. The rod 9 is immersed in the molten steel filled in the mold 2. The adjustment of the immersion depth can be performed by controlling the moving distance of the entire arm 6 downward. When the measurement is completed, perform the reverse operation to return to the original state. All of these operations can be performed automatically by the control device. Further, a mechanism that can automatically attach and detach the probe 8 to and from the tip of the arm 6 of the fully-automatic manipulator 1 can be provided at the tip of the arm 6. In the fully automatic manipulator 1 equipped with this mechanism, a probe storage (not shown) is provided near the manipulator 1, and the tip of the arm 6 on which the probe 8 is not mounted is connected to the probe storage. Probe 8 stored in By touching, the probe 8 can be automatically attached to the tip of the arm 6. In addition, the probe 8 can be automatically removed after the measurement is completed. Fig. 12 shows the above-mentioned fully automatic manipulator 1 provided on the outside of the long side of the mold 2 outside the long side wall of the mold 2 so that the support column 7 can be moved back and forth in the long side direction of the mold 2. . In the figure, 71 is a probe storage. The operation other than the movement of the column 7 is exactly the same as that of the fully automatic manipulator described above. By using this fully automatic manipulator 1, the detection rod can be moved over a wider range.

 In the above-described fully automatic manipulator, the immersion depth of the detection rod is adjusted by moving the entire arm 6 up and down. However, a telescopic means for directly moving the probe 8 up and down may be provided. As an example, a mechanism for moving the detection rod in the vertical direction using an air cylinder or a hydraulic cylinder can be considered.

 The movement of the fully-automatic manipulator described above can be automated by registering the measurement position in the mold in advance in the control device by a method such as coordinate input before starting the measurement. Of course, a configuration in which the operation is switched to manual operation during the operation and the fine adjustment of the measurement position can be performed may be adopted. Also, the control of the immersion depth of the detection rod can be controlled by its absolute position based on the level information in the mold.

 Also, in order to reliably detect the vibration caused by the generated Karman vortex, the orientation of the mounting surface on which the sensor for vibration detection on the detection rod is mounted can be adjusted within a range of 180 degrees in the axial direction of the detection rod. Is also good.

In the above-mentioned manipulator, since the entire portion of the detection rod immersed in the molten steel is used as the measurement site, it cannot be determined at which depth position the detected vibration mainly occurs. Therefore, the cross-sectional shape of the sensing rod other than the tip for measuring the flow velocity is shaped so that the occurrence of Karman vortices is suppressed compared to the tip, and by using such a sensing rod, the surface of the molten steel can be reduced. To minimize the occurrence of Karman vortices at a certain depth position from the point where the flow velocity is to be measured, and detect vibrations mainly caused by Karman vortices generated at a specific depth position Thus, the flow velocity at the specific position can be measured. To suppress the generation of Karman vortex The streamline is excellent as a simple cross-sectional shape.

 FIG. 13 (a) is an example of a detection rod adopting such a shape. The detection rod 9 is composed of a cylindrical tip portion 13 for measuring the flow velocity and a shaft portion 14 other than the tip portion. Since the cross section of the shaft 14 is an elongated ellipse whose cross section is a kind of streamline, as shown in FIG. 13 (b), the longitudinal direction of the cross section of the shaft 14 and the molten steel By immersing the detection rod 9 in the molten steel so that the flow direction matches, the generation of the Karman vortex by the shaft portion 14 can be suppressed as much as possible. Therefore, the detection rod 9 is immersed, the tip 13 is kept at a specific depth position in the molten steel, and the vibration mainly caused by the Karman vortex generated at the specific depth position is detected. Thus, the flow velocity at that position can be measured. In FIG. 13 (a), the length of the cylindrical end portion 13 is about 10 times the diameter R of the end portion 13 in FIG. 13 (a). Is about 3 to 15 mm.

 In the above example, the tip 13 is cylindrical, but this shape has the characteristic that Karman vortices can be generated regardless of the flow direction of the molten steel, regardless of the direction. In addition, as shown in FIG. 14, the shape of the distal end portion 13 may be a triangular cross-sectional shape. As shown in Fig. 14, when this triangular prism-shaped detection rod is immersed in molten steel so that the bottom of the cross-sectional shape of its tip 13 faces the flow s of molten steel, Karman vortex c is formed. It is known to occur easily. This shape of the observation rod has high sensitivity and directivity as a characteristic, but has the disadvantage that the characteristic is liable to change if the corner of the triangular prism is melted and the shape is changed. Usually, the measurement time is 30 minutes to 45 minutes, but this detection rod can sufficiently withstand a short measurement time of about 10 minutes. The detection rod described above can be used for a semi-automatic or manual manipulator described later, in addition to the fully automatic manipulator described above.

Also, the direction of the flow of molten steel can be detected by utilizing the fact that the level of the output signal varies depending on the axial position of the detection rod to which the vibration detection unit is attached. Detecting the flow direction of the molten steel is very effective for detecting signs of drift of the molten steel in the mold. This detection method first involves immersion of the detection rod. By using a vibration detector that changes the level of the signal obtained depending on the direction of the detection rod with respect to the flow of molten steel during immersion, the detection rod is rotated around its axis to change its direction. The rotation angle of the detection rod is detected when the peak with the maximum spectrum intensity extracted by the maximum is the largest. Then, the direction of the flow of molten steel is determined from the rotation angle.

 FIG. 15 shows an example of a probe 8 having a function of detecting the flow direction of molten steel. In this probe 8, the upper end of the columnar detection rod 9 is fixed to the detection rod mounting part 15. The upper part of the detection rod mounting part 15 is connected to the front inner pipe 10 having a cylindrical shape, and a part of the front inner pipe 10 having a cylindrical shape has a rectangular cross section. A flat mounting portion 17 is formed, and the vibration detecting portions 16 are mounted on both front and back surfaces of the mounting portion 17. Further, a pulse motor 18 for rotating the detection rod 9 and a rotary encoder 19 for detecting a rotation angle generated by the rotation are mounted on the upper part of the front inner pipe 10.

 When the probe 8 is immersed in molten steel, if the mounting surface of the mounting part 17 is parallel to the flow direction f of the molten steel as shown in Fig. 16 (b), the probe 8 is transmitted through the detection rod 9. Vibration B caused by the Karman vortex c acts perpendicularly to the mounting surface of the mounting part 17, and the vibration detecting part 16 can selectively and efficiently detect the vibration caused by the generation of the Karman vortex c. it can. This is because the direction of the vibration B caused by the generation of the Karman vortex c matches the bending direction of the mounting portion 17 where the vibration detecting portion 16 is mounted. However, as shown in FIG. 16 (a), if the mounting surface of the mounting portion 17 is not parallel to the flow direction f of the molten steel, the direction of the vibration B caused by the generation of the Karman vortex c is Since it does not coincide with the deflection direction of 7, the vibration detecting unit 16 cannot selectively and efficiently detect the vibration caused by the occurrence of the Karman vortex c. Therefore, the detection rod 9 is rotated by the pulse motor 18, and based on the signal obtained from the vibration detection section 16, the peak having the maximum spectral intensity extracted by the first determination means described above becomes the largest. When the rotation angle of the detection rod 9 from the predetermined reference position, that is, the angle in FIG. 16 (b), is detected by the rotary encoder 19, the flow of molten steel is detected. Direction can be known.

The above-mentioned triangular detection rod can be used as the detection rod of the probe. You. In this case, when attaching the triangular prism-shaped detection rod to the detection rod mounting part, mount it so that the wall of the detection rod facing the flow of molten steel is perpendicular to the direction of deflection of the vibration detection part mounting part. As described above, this probe has directionality as a characteristic of the detection rod itself, and thus has excellent sensitivity for detecting the direction of the flow of molten steel. However, as described above, the characteristics tend to change due to the shape change due to the erosion at the corners of the triangular prism, but it is effective for short-time measurement.

 The probe described above can be used not only for the fully automatic manipulator described above but also for a semi-automatic or manual manipulator described later.

As an example of the use of semi-automatic probe operation, a manipulator with a structure as shown in Fig. 17 can be considered. In this manipulator 50, a guide rail 51 extending in the long side direction of the mold 2 is disposed on one short side of the mold 2 and a cylinder 53 pushes and pulls the guide rail 51 on the guide rail 51. A moving body 52 that moves forward and backward is provided so as to be slidable, and furthermore, an arm 55 is provided from the moving body 52, one end of which is pivotally connected to the top surface thereof and which can be tilted by a lifting cylinder 54 that comes and goes from the top surface. The probe 56 is attached to the end of the arm 55 with the probe 56 facing downward. The position of the probe 56 at the measurement position by the manipulator 50 is as follows. First, the arm 55 is lifted by the lifting cylinder 54 and the probe 56 is lifted from the upper surface of the mold. To push probe 56 forward. When the probe 56 reaches a predetermined position, the lifting cylinder 54 is lowered, and the probe tip is drawn into the molten steel so as to draw an arc. The arm 55 can also have an extendable stroke to increase the stroke. In this manipulator 50, the replacement work of the probe 56 is performed manually. The manipulator described above is a manipulator that fully or semi-automatically performs the probe operation, but a manipulator that is manually operated as shown in FIG. 18 is also conceivable. . This manipulator is horizontally mounted on the upper surface opening of the mold 2 in the width direction, and provided with a bridging rod 62 having one end as a fulcrum 61 and the other end supported by a support 60. The probe 63 is slidably mounted on the mounting rod 62 in the longitudinal direction of the mounting rod 62, and the mounting rod 62 lifted in advance with the fulcrum 61 as the center of rotation is lowered. The detection rod 64 held in the lobe 63 is immersed in a predetermined position in the molten steel.

 The above-mentioned measurement by the manipulator is intended for stationary long-term measurement, but sometimes it is necessary to make short-time measurement simply and temporarily. To cope with such a case, a hand-held manipulator for simple measurement is required. The following is proposed as this manipulator.

 FIG. 19 and FIG. 20 show this handheld manipulator for simple measurement. This manipulator 20 has a configuration in which a probe 30 is held through a mount 25. Then, as shown in FIG. 21, the operator holds the operating rod 28 extending from the pedestal 25 with both hands, and immerses the detecting rod 21 held by the probe in the molten steel. Perform the measurement. In this case, it is important to position the probe 30 in a posture that can reliably capture the vibration caused by the Karman vortex, and to remove the hand-held vibration component from the measured vibration components. The inventor of the present invention has solved the former problem by devising a structure for mounting the probe 30 on the pedestal 25, and has solved the latter problem by attaching an accelerometer 29 to the pedestal 25 and probing vibration caused by hand-holding. The problem was solved by discriminating from the vibration detected by the 30 vibration detection means. Hereinafter, this will be described in detail with reference to FIGS. 19 and 20. As shown in FIGS. 19 and 20, the hand-held manipulator 20 has a structure in which a probe 30 is mounted on a pedestal 25. The probe 30 used here is different from the probe used for each of the manipulators described above, and has a configuration in which a detection rod 21 immersed in a mold and vibration from the detection rod 21 are used. It comprises a holding part 22 that holds the detection rod 21 while receiving the transmission.

The holding part 22 has a flat thin part 23 formed in the middle part in the longitudinal direction. A strain gauge 24 for detecting Karman vortex vibration and converting the vibration into an electric signal is attached to this surface. I have. In addition, a fitting portion 31 having a plane parallel to the surface of the thin portion 23 is provided at the uppermost portion of the holding portion 22. The mount 25 has a fitting hole 27 into which the fitting portion 31 provided in the holding portion 22 is fitted. The inner surface of the insertion hole 27 is provided with a plane where the plane of the insertion portion 31 contacts, and the inner surface shape of the insertion hole 27 and the outer surface shape of the insertion portion 31 are the same. . Therefore, the probe 30 can be fixed to the pedestal 25 by fitting the fitting portion 31 into the fitting hole 27. As described above, the operation rod 28 is attached to the gantry 25, and the axial direction of the operation rod 28 is parallel to the plane provided on the inner surface of the insertion hole 27. Installed as Therefore, the plane on which the strain gauge 24 of the thin portion 23 of the probe 30 is attached is parallel to the axial direction of the operation rod 28.

 Therefore, next, a measurement method using the hand-held manipulator 20 will be considered. The flow of molten steel discharged from the discharge port of the immersion nozzle in the mold is almost parallel to the long side direction of the mold. Then, the operator stands by the side wall of the short side of the mold, and makes the axial direction of the operation rod 28 parallel to the long side direction of the mold. As shown in FIG. If the detection rod 21 is immersed while holding 0, the flow of the molten steel becomes parallel to the plane on which the strain gauge 24 is mounted. Therefore, the operator simply stands by the side wall of the short side of the mold and holds the hand-held manipulator 20, so that the Karman vortex is always generated with respect to the flow of molten steel in the mold. The detection rod 21 can be immersed so that it is most likely to occur, and easy and accurate measurement can be performed.

 An accelerometer 29 is attached to the operation rod 28 of the hand-held manipulator 20 described above. The accelerometer 29 detects the vibration of the gantry 25 generated when measuring using the hand-held manipulator 20. Further, a discriminating means for discriminating the vibration of the pedestal 25 captured by the accelerometer 29 from the vibration obtained from the strain gauge 24 is provided, and this discriminating means is simultaneously used for the measurement using the manipulator. There is a need. The discriminating means includes, for example, a spectrum curve obtained by performing an FFT process on a detection signal obtained by converting a vibration obtained from the strain gauge 24 into an electric signal, from a frame 25 obtained by the accelerometer 29. There is a method of removing a spectrum component having a spectrum curve obtained by performing FFT processing on a signal obtained by converting vibration into an electric signal.

 The structures of the probes and the manipulators described above are merely examples, and probes and manipulators having other structures can be employed.

As the detection rod to be attached to the probe, one having excellent erosion resistance is used. This implementation In the example, a material coated on the surface with a thickness of 500 zm to 1500 im using any of zirconia, silicide zirconia, and calcium zirconia excellent in erosion resistance is used. The reason for setting the thickness of the coating layer to 500 m to 1500 m is that if it is less than 500, measurement for 30 minutes or more cannot be expected, and if it exceeds 1500 _im, it becomes technically difficult to coat. is there. The present inventor compared the conventional detection rod with the detection rod coated with zirconia described above with respect to erosion resistance. The results were as follows. When the detection rod used a Mo-Zn〇2-based simmet tube, the local erosion rate at the meniscus layer immersion position was 1.9 mZsec, and the immersion was 1 After 0 minutes, the remaining thickness is less than 1.5 mm. If the remaining wall thickness is 1.0 mm or less, the usage limit is about 12 minutes. On the other hand, the one coated with zirconium had a local erosion rate of 0.6 am / sec at the dipping position of the meniscus layer in the coating layer. Therefore, if a coating layer of 1000 // m (= 1 mm) is formed on the cermet, it will take about 25 minutes for the coating layer to melt away. Then, a 1000-meter coating of zirconia on a Mo-ZnO2-based cermet tube can measure over 30 minutes.

 Incidentally, zirconia, silicone zirconia, and calcium zirconia are heavy materials, although they have excellent erosion resistance to the meniscus layer. In addition, what is actually required to have erosion resistance is the portion located in the meniscus layer when the sensing rod is immersed in molten steel. Therefore, in order to make the sensing rod lighter, the sensing rod is manufactured using Sialon, which is a material with low erosion resistance but light, and when the sensing rod is immersed in molten steel, the part located in the meniscus layer is removed. At least the surface of the area included may be covered with a sleeve made of any one of zirconia, silica zirconia, and calcium zircon air.

FIG. 22 is an illustration showing a case where a detection rod using the sleeve 41 made of the above-described material is immersed in molten steel. As shown in the figure, when the detection rod 9 is immersed in the molten steel 44 of the mold 45, the molten steel 44 and the molten powder 42 The portion that comes into contact with the meniscus layer 4 3 formed between them is covered with the sleeve 41 made of the above-mentioned material, thereby increasing the erosion resistance to the meniscus layer 4 3. As shown in Fig. 23, the flow rate of the molten steel discharged from the left and right discharge ports 101 and 102 of the immersion nozzle 100 in Mold 2 A measurement can be made. Fig. 24 shows the screen of the monitoring panel that displays the progress of the process of obtaining the flow velocity when measuring the flow velocity. As shown in Fig. 19, the process of obtaining the flow velocity can be displayed in real time. This was realized by using the moving block FFT processing method.

 This monitor panel displays, for example, the flow velocity value, the graph of the change over time in flow velocity, the detection signal waveform, and the spectrum carp after FFT processing for the left and right sides of the mold, respectively, for comparison and display on the left and right. The drift can be grasped. The fact that the drift detected by the monitoring panel is reflected in active control such as electromagnetic brake control, eliminates abnormal drift in the mold, and improves product quality and increases productivity by increasing production speed. Can be. Industrial applicability

The invention according to claim 1 and claim 3 is an apparatus and a method for analyzing the vibration caused by the occurrence of Karman vortex to measure the flow velocity of the molten metal, wherein the frequency of the detection signal obtained by the vibration detection means provided in the detection rod is It discloses a procedure for specifying the frequency component to be subjected to the calculation of the flow velocity measurement from the components. By using this procedure, when no Karman vortex is generated, erroneous detection such as the high-frequency vibration caused by the undulation of the molten metal being caused by the Karman vortex can be prevented, and various disturbances can be eliminated. In addition, the maximum flow velocity of the molten metal can be determined accurately, which can cause uneven solidification of the molten steel in the mold and disturbance of the molten steel surface, reduce the material quality, and reduce the production efficiency. And the signs of drift in the mold can be detected at an early stage. Therefore, abnormal drift in the mold is eliminated by reflecting the detected sign of drift in active control such as electromagnetic brake control. The invention according to claims 2 and 5 can improve the product quality and increase the productivity by increasing the manufacturing speed. The invention according to claim 2 uses the FFT for the frequency component analysis of the detection signal and provides the FFT for the analysis. The moving block FFT processing method is used to form the FFT frame that is the data to be processed. Therefore, since a large number of blocks can be secured with a short response time to form an FFT frame, which is data to be processed for fast Fourier transform, the frequency resolution of the spectrum curve obtained by the FFT processing can be increased. Therefore, the responsiveness and accuracy of the flow velocity measurement can be improved.

 The invention according to claim 4 adds vibration detecting means, detecting rod rotating means, rotation angle detecting means, and molten metal flow direction detecting means to the configuration of the molten metal flow velocity measuring device according to claim 3. Used. Therefore, not only the flow velocity of the flow of the molten metal but also its direction can be detected.

 The invention according to claim 6 is provided with a fully automatic manipulator having a column, an arm turning means, an arm bending / extending means, and a vertical movement means for moving the tip end position of the detection rod. Therefore, in a narrow working space between the tundish and the mold in the continuous manufacturing facility, the detection rod can be safely and efficiently immersed accurately at a predetermined position of molten steel in the mold. In addition, when measurement is not performed, the user can wait outside the work area, so that other work is not obstructed.

 The invention according to claim 7 includes a fully automatic manipulator having an arm extending / contracting means. Therefore, when measurement is not performed, the manipulator can be kept out of the way by contracting the arm.

 The invention according to claim 8 is provided with a fully automatic manipulator having horizontal moving means for horizontally moving the support column in the long side direction of the mold. Therefore, the detection rod can be moved over a wider range.

According to a ninth aspect of the present invention, there is provided a system for controlling the molten metal level detecting means and the up and down moving means in the mold based on information output from the molten metal level detecting means. It has a fully automatic manipulator with control means. Therefore, the control for accurately immersing the detection rod at the immersion position can be automated using the vertical movement means. The invention according to claim 10 is characterized in that the probe for holding the detection rod is automatically attached and detached. And a fully automatic manipulator having Therefore, it is possible to automate the attachment / detachment of probes to Manipyure. Therefore, it is possible to automate the replacement of the exhausted detection rod, and to more fully automate the measurement operation.

 The invention according to claim 11 has a comprehensive management means for comprehensively managing and controlling various means of the fully automatic manipulator. Therefore, it is possible to automate the process from mounting the probe to moving to the measurement location, further immersing the detection rod in the molten metal of the mold, lifting the probe at the end of the measurement, retreating the probe, and removing the probe.

 In the invention according to claim 14, vibration of the gantry is detected by the manipulator having the accelerometer mounted on the gantry and the accelerometer provided on the detection rod, and the vibration of the gantry is detected from the vibration detected by the vibration detecting means mounted on the detection rod. A discriminating means for discriminating the components. Therefore, the influence of the vibration of the gantry, which is an error factor of the flow velocity measurement, can be eliminated.

 In the invention according to claim 15, since the cross-sectional shape of the detection rod other than the tip for measuring the flow velocity is shaped so as to suppress the occurrence of Karman vortices as compared with the tip, the molten metal The generation of Karman vortices at the depth position on the way from the surface to the depth position where the flow velocity is to be measured can be suppressed as much as possible. Therefore, by immersing the detection rod of such a shape at a specific depth position, the tip is kept at a specific depth position in the molten metal, and the Karman vortex generated at this specific depth position is mainly The flow velocity based on the vibration as a factor can be measured.

In the invention according to claim 16, a coating layer having a thickness of 500 wm to 1500 im made of any of zirconia, silicide zirconia and calcium zirconia is provided on the surface of the detection rod. Therefore, the surface of the sensing rod is protected by the molten powder attached to the surface of the sensing rod. The contact of the surface of the sensing rod with the meniscus layer formed between the sensing rod and the surface of the sensing rod is reduced, and erosion of the sensing rod can be suppressed.

 In the invention according to claim 17, when the detection rod is immersed in the molten metal, the surface of a range including at least a portion located in the meniscus layer is made of any of zirconia, silicate zirconia, or calcium zirconia as a material. Covered with a sleeve. Therefore, the erosion resistance of the detection rod to the meniscus layer can be increased.

Claims

The scope of the claims

1. A detection rod consisting of a heat-resistant material rod equipped with vibration detection means is immersed so as to block the flow of the molten metal, and the presence of the detection rod in the flow causes the detection rod to be located downstream of the detection rod. Vibration of the detection rod caused by the generated Karman vortex is detected as a continuous signal by the vibration detection means, and the flow rate of the molten metal is obtained by calculation from the relational expression between the frequency of the detection signal and the flow rate of the molten metal. A frequency component analysis process (A) for analyzing a frequency component of the detection signal; and a peak envelope curve obtained by connecting adjacent peaks of the spectrum curve obtained from the frequency component analysis process. Multiple peaks are extracted, and the difference between the largest and the smallest of these peaks is caused by the Karman vortex only when the difference between them is more than a certain value. The first-size constant to acknowledge the presence of vibration (B) that,

 In the case where the existence of the vibration caused by the Karman vortex is recognized in the first determination, a certain ratio or more of the extracted peak having the largest spectral intensity among the plurality of the extracted peaks is determined. A second determination (C) in which only the extracted peaks having a vector intensity are selected, and the extracted peaks having the highest frequency are distinguished among the extracted peaks;

 A flow velocity calculation (D) of the molten metal performed using the frequency of the peak that has been distinguished in the second determination;

 A method for measuring the flow velocity of a molten metal comprising:

2. The high-speed Fourier transform used in the frequency component analysis process and a block formed by combining a predetermined number of blocks in a sequence formed by continuously sampling the detection signals in a unit time in the order of formation. Each time the latest fast Fourier transform frame of the Fourier transform frame is formed, the block is inserted at the head of the last fast Fourier transform frame formed, and 2. The method for measuring the flow velocity of a molten metal according to claim 1, wherein the succeeding blocks are sequentially shifted, and the final blocks are discarded and formed.

3. The detection rod consisting of a heat-resistant material rod equipped with vibration detection means is immersed so as to block the flow of the molten metal, and the presence of the detection rod in the flow causes the detection rod to be located downstream of the detection rod. Apparatus for detecting the vibration of the detection rod caused by the generated Karman vortex as a continuous signal by the vibration detection means, and calculating the flow velocity of the molten metal by calculation from the relational expression between the frequency of this detection signal and the flow velocity of the molten metal A frequency component analyzing means for analyzing a frequency component of the detection signal,

 A plurality of peaks in a peak envelope curve obtained by connecting adjacent peaks in the spectrum curve obtained from the frequency component analysis means are extracted, and among these peaks, the spectrum intensity is the largest. First judgment means for recognizing the existence of vibrations caused by Karman vortices only when the difference between the minimum and the minimum is greater than a certain value;

 When the presence of the vibration caused by the Karman vortex is recognized by the first determination means, a certain ratio or more of the extracted peak having the maximum spectral intensity among the plurality of extracted peaks Second determining means for selecting only the extracted peaks having the following spectral intensities, and distinguishing the extracted peaks having the highest frequency from the selected peaks:

 A molten metal flow velocity measuring device, which is a molten metal flow velocity calculating means that performs using a frequency of a peak sharply distinguished in the second determination.

 4. The vibration detecting means has a structure in which the output signal has a different level depending on the direction of the detection rod with respect to the flow of the molten metal when the detection rod is immersed, and

 In addition to the configuration of the molten metal flow rate measuring device according to claim 3,

 Rotating means for changing the direction of the detection rod by rotating the detection rod around an axis;

 Rotation angle detection means for detecting the angle of rotation,

When the detection rod is rotated by the rotation means, and the peak at which the spectrum intensity extracted by the first determination means is maximum becomes the largest, the rotation angle detected by the rotation angle detection means is detected. From, the molten metal flow direction determining means for determining the direction of the molten metal flow, A molten metal flow velocity measuring device comprising:

 5. A high-speed system in which a fast Fourier transform is used for the frequency component analysis means and a predetermined number of blocks are formed by continuously connecting a predetermined number of blocks in which the detection signal is formed by a data sequence sampled continuously in a unit time. Each time the latest fast Fourier transform frame of the Fourier transform frame is formed into the latest block, the block is inserted at the beginning of the last formed fast Fourier transform frame, and 5. The molten metal flow rate measuring device according to claim 3, further comprising means for sequentially shifting the blocks to be formed and discarding and forming the last block.

 6. A vertical column (7),

 A base end is suspended from the top of the support (7), and the detection rod (9) is moved so that the rod-shaped detection rod (9) is parallel to the opening surface of the mold (2). An arm (6) with the probe (8) held at its tip,

 Turning means for turning the arm (6) horizontally;

 A joint provided at an intermediate portion of the arm (6) such that the detection rod (9) is in a vertical upright state with its tip end directed downward with respect to the upper opening surface of the mold (2). Bending and extending means for bending or extending the arm (6) with the part (12) as a fulcrum, and

 When the detection rod is in the upright state, the position of the tip of the detection rod (9) is moved up and down, and the molten metal (M) in the mold (2) is moved toward the detection rod ( 9) up and down moving means to immerse and exit

 The molten metal flow velocity measuring device according to any one of claims 3 to 5, further comprising a fully-automated manipulator having:

 7. The molten metal flow velocity measuring device according to claim 6, wherein the fully-automatic manipulator has expansion / contraction means for extending / contracting the arm (6) in an axial direction thereof.

 8. The molten metal flow velocity measuring device according to claim 6, wherein the fully automatic manipulator has horizontal moving means for horizontally moving the support (7) in a long side direction of the mold (2).

9. The fully automatic manipulator moves the molten metal (M The method according to any one of claims 6 to 8, further comprising: control means for performing control of the vertical movement means based on information output by the water level detection means. A device for measuring the flow rate of molten metal.

 10. The end of the arm (6) is provided with attachment / detachment means for automatically attaching / detaching the probe (8) holding the detection rod (9). The flow rate measuring device for molten metal according to claim 1.

 1 1. When the fully-automatic manipulator has the turning means, the bending and extending means, the up and down moving means, and the expanding and contracting means, the horizontal moving means, and the attaching and detaching means, these means are provided. The flow rate measurement of a molten metal according to any one of claims 6 to 10, comprising a comprehensive management means for comprehensively controlling and controlling the flow rate of the molten metal.

12. A horizontal moving means having a moving body (52) that moves forward and backward by projecting or retreating above the upper surface opening of the mold (2), and one end pivotally attached to the moving body (52) as a rotation fulcrum. The other end of the arm (55) that tilts in a circular arc up and down along the advance / retreat direction is attached to the other end of the arm (55) so that the tip of the detection rod held by the probe (56) is downward. The molten metal flow velocity measuring device according to any one of claims 3 to 5, further comprising a semi-automatic manipulator having a tilting means having the probe (56) suspended therefrom.

 13. An erecting rod (62) that is horizontally suspended at the top opening of the mold (2), one end of which is a rotating fulcrum and the other end is tilted in an up and down arc.

In the course of (62), the probe (63) is vertically slidably slid in the axial direction of the erection rod (62) such that the tip of the detection rod (64) held by the probe (63) faces downward. The molten metal flow velocity measuring device according to any one of claims 3 to 5, further comprising a manipulator having the installed erection rod (62).

14. A manipulator having a gantry (25) to which the detection rod having the vibration detection means is attached, and an accelerometer (24) attached to the gantry (25), The manipulator used by the operator (H) holding the gantry (25) by hand, and the gantry (25) captured by the accelerometer (24) from the vibration detected by the vibration detecting means. Discrimination means for discriminating vibration The molten metal flow velocity measuring device according to any one of claims 3 to 5, comprising:

1 5. The cross-sectional shape of the detection rod other than the tip portion (13) for measuring flow velocity has a shape in which the generation of Karman vortices is suppressed as compared with the tip portion (13). The apparatus for measuring the flow velocity of a molten metal according to any one of the preceding claims.

 16. A detection rod used in the flow velocity measuring device according to any one of claims 1 to 15, wherein

 A detection rod with a coating layer of 500 nm to 1500 m made of zirconia, silicate zirconia, or calcium zirconia on the surface.

 17. A detection rod (9) for use in a flow velocity measuring device according to any one of claims 1 to 15, wherein

 The surface of at least the area including the existence area of the meniscus layer (43) in the longitudinal direction of the detection rod (9) immersed in the molten metal is made of any one of zirconia, silicon zirconia, and calcium zirconia. A detection rod covered with a sleeve (41) made of material.