JP3566876B2 - Non-contact flow velocity detection method and apparatus - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-contact flow velocity detection method and apparatus, and in particular, to constantly control the flow velocity of a conductive fluid under a free surface of a metal continuous casting facility by mechanically controlling the inclination between a molten metal surface and a detection coil. The present invention relates to a novel improvement for obtaining a high-precision flow rate by maintaining the same.
[0002]
[Prior art]
Conventionally, as disclosed in JP-A-9-33554, a non-contact flow velocity detector proposed for a continuous casting facility for molten metal will be described with reference to FIG.
Conventional non-contact flow rate detector, a core 5 with an excitation coil 4 for applying a low-frequency magnetic field phi ₀ in a measurement target of the conductive fluid 100 disposed in non-contact with molten metal surface 100a, on its periphery It comprises a detection coil 6 of a flow velocity detector head 15 for detecting a magnetic field generated by the action of the exciting coil 4 and the conductive fluid 100.
At this time, the low frequency and the high frequency from the low frequency oscillator 1 and the high frequency oscillator 2 are applied to the exciting coil 4 via the amplifier 3, and the low frequency magnetic field and the high frequency magnetic field from the exciting coil 4 enter the conductive fluid 100. As a result, an eddy current is formed in the conductive fluid 100. When the conductive fluid 100 is moving at a certain speed, an induced current generated by the action of the low-frequency magnetic field and the speed is formed. Therefore, the eddy current caused by the interlinkage of the velocity component magnetic flux φv generated by the induced current and the magnetic flux generated in the direction obstructing the low-frequency magnetic field regardless of the velocity is applied to the detection coil 6 arranged around the excitation coil 4. The eddy current magnetic flux φs generated by this is detected. As the two magnetic fluxes φs and φv pass through the detection coil 6, the eddy current component voltage es and the velocity component voltage ev are output to the detection coil 6 as the detected electromotive voltage 6a.
Here, since these two components have a phase difference of 90 ° from each other, the rectifier circuit 8 and the phase rectifier circuit 9b pass the high-frequency filter 7a and the low-frequency filter 7b to calculate the velocity component voltage and the eddy current from the detected electromotive voltage 6a. In this method, a flow velocity V composed of a velocity component voltage is extracted through a gap correction circuit 10b. The core 5 is configured to detect the position by changing the position by 180 degrees alternately in the forward and reverse directions.
[0003]
[Problems to be solved by the invention]
However, in the above-described prior art, a method is used in which a velocity component voltage is separated from an electromotive voltage only through a phase rectifier circuit, and this method cannot completely separate a velocity component voltage and an eddy current component voltage. As a result, the eddy current component voltage was output with the speed component voltage remaining. The component due to the eddy current component voltage remaining in the velocity component voltage is simply referred to as a residual component △ es. In addition, the eddy current component voltage may fluctuate due to the inclination existing between the flow velocity detector head and the surface of the conductive fluid, or the shape of the surface of the conductive fluid, for example, undulation or undulation caused by the flow.
This is because the distance (gap) between the conductive fluid and the conductive fluid is displaced in the plane of the detection coil due to the inclination and the undulation, and the eddy current component magnetic field penetrating the detection coil changes accordingly, and as a result, the eddy current component voltage fluctuates. Will be. As described above, since the eddy current component voltage remains in the velocity component voltage even after the phase rectification, the velocity component voltage ev (= △ es) is apparently generated even when the conductive fluid is stationary. Will be. Therefore, the apparent velocity component voltage ev changes depending on the shape of the molten metal surface irrespective of the flow velocity due to the residual component △ es, which causes a decrease in the measurement accuracy of the flow velocity detection (shown in FIG. 13). This has made it difficult to measure below the surface.
[0004]
The present invention has been made in order to solve the above-mentioned problems, and in particular, the flow rate of the conductive fluid under the free surface of the continuous casting equipment for metal is mechanically controlled by the inclination between the molten metal surface and the sensing coil. It is an object of the present invention to provide a non-contact flow velocity detecting method and apparatus which can obtain a high-precision flow velocity by controlling and always keeping a horizontal level.
[0005]
[Means for Solving the Problems]
The non-contact flow velocity detection method according to the present invention is generated by applying two alternating currents from a low-frequency oscillator and a high-frequency oscillator to an excitation coil of a core arranged in a non-contact manner with respect to a conductive fluid to be measured. The low-frequency magnetic field and the high-frequency magnetic field are incident on the conductive fluid, and the eddy current component voltage generated by interlinking the magnetic flux generated in the direction obstructing the low-frequency magnetic field generated by the magnetic field coil; The flow velocity of the conductive fluid is obtained by using a flow velocity detector head having a detection coil for detecting a low-frequency magnetic field from the sensor and a velocity component voltage generated by the relative movement of the conductive fluid to be measured. the non-contact velocity detection method in a sensor mount having a flow velocity detector heads, tiltably in the detector body with said sensor mount is provided vertically movable A frame member, a pressing member fixed to the detector main body and passing through a hole in the bottom of the frame, and provided between the pressing member and the bottom to constantly urge the frame downward. A holding spring, an L-shaped engaging jig which engages with the bottom and is tiltable by a mounting portion of the detector main body, and a tilt adjusting motor provided on a motor mounting base of the detector main body. And a protruding piece that is provided on the tilt adjustment motor so as to be freely retractable and tilts the tilt adjustment jig, and the flow velocity is detected by at least one pair of tilt detection coils provided below the flow velocity detector head. A method of controlling the inclination posture of the flow velocity detector head by the inclination adjustment motor so that a difference between each inclination detection value from each inclination detection coil becomes zero. Guidance that is the subject A low-frequency magnetic field and a high-frequency magnetic field generated by applying two alternating currents from a low-frequency oscillator and a high-frequency oscillator to an excitation coil of a core placed in a non-contact manner with respect to a conductive fluid are incident on the conductive fluid Accordingly, the eddy current component voltage generated by the magnetic flux generated in the direction obstructing the low frequency magnetic field generated by the magnetic field coil, and the low frequency magnetic field from the magnetic field coil and the conductive fluid to be measured are relative to each other. In a non-contact flow velocity detecting device that obtains the flow velocity of the conductive fluid using a flow velocity detector head having a detection coil for detecting a velocity component voltage generated by moving, the flow velocity detector head At least one pair of tilt detection coils provided at a lower portion, a sensor mounting base having the flow velocity detector head, and the sensor mounting base are provided so as to be movable up and down. A frame body tiltably provided on the output body, a holding member fixed to the detector body and passing through a hole in a bottom portion of the frame body, and the frame body provided between the holding member and the bottom portion; A pressing spring for constantly biasing the detector body downward, an L-shaped inclination adjusting jig which engages with the bottom portion and is tiltable by a mounting portion of the detector main body, and a motor mounting of the detector main body. A tilt adjusting motor provided on a table, and a protruding piece provided on the tilt adjusting motor so as to be able to move in and out of the tilt adjusting jig to tilt the tilt adjusting jig, and the tilt adjusting jig and the frame body are provided by the tilt adjusting motor. The inclination of the flow velocity detector head with respect to the conductive fluid is adjusted via the above .
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a non-contact flow velocity detecting method and apparatus according to the present invention will be described with reference to the drawings. Note that the same or equivalent parts as those in the conventional example will be described using the same reference numerals, and the configuration until the flow velocity V is extracted from the detection coil 6 is the same as that in FIG. I do.
FIGS. 1 to 4 show the overall configuration of the non-contact flow velocity detecting device according to the present invention, in which an eddy current component voltage es from the flow velocity detector head 15, a velocity component voltage ev, and a pair of inclinations added in the present invention. The inclination detection values θ ₁ and θ ₂ from the detection coils 40 and 41 (shown in FIG. 2) are input to the controller 30, and the flow velocity detector head 15 is attached to the detector main body 16 having the suction cup 16a via the mounting member 17. It is provided on a sensor mounting base 19 which is provided on a frame 18 which is provided so as to be tiltable. The sensor mount 19 is vertically movably provided by an elevating motor 20 and a screw 21 provided above the frame 18.
[0007]
A bar-shaped pressing member 23 is provided on a bottom 18a of the frame 18 via a compression pressing spring 22. A lower end 23a of the pressing member 23 passes through a hole 18b of the bottom 18a and the detector main body 16 has a lower end 23a. , The frame 18 is constantly urged downward by the spring force of the pressing spring 22 . Further, an upper end 25a of a tilt adjusting jig 25 which is engaged with the bottom portion 18a of the frame 18 and has a substantially L-shaped overall shape and can be tilted by the mounting portion 24 is provided on the detector main body 16. The tilt adjustment motor 27 of the motor mount 26 is tilted by a protruding piece 28 which can freely move in and out (for example, using a well-known feed screw). FIG. 5 schematically shows the relationship between the tilt adjusting jig 25, the frame 18, and the presser spring 22. Further, a personal computer 31 and a laser printer 32 are connected to the controller 30, and an operation control section 33 for performing various operations (elevation, left / right tilting, etc.) of the elevating motor 20 and the tilt adjusting motor 27 is provided. It is connected to the controller 30.
[0008]
The arrangement configuration of the excitation coil 4, the detection coil 6, and the inclination detection coils 40 and 41 of the flow velocity detector head 15 shown in FIG. 2 is provided as shown in FIGS. , 41 are provided at positions closer to the molten metal surface 100a than the respective coils 4, 6. Further, the tilt detection coils 40 and 41 are configured as shown in FIG. 8, and the terminals A, B and C of the tilt detection coils 40 and 41 are connected to a well-known bridge circuit (or balance circuit) shown in FIG. 200), and is constituted by variable resistors VR1 and VR2 adjusted to values such that a voltage value equivalent to the voltage value obtained by each of the tilt detection coils 40 and 41 is obtained. The obtained output (voltage value) 200a is output after being amplified via an input transformer 201 and an amplifier 202 composed of, for example, a well-known lock-in amplifier with a gain of 2,000. Note that the above-described inclination detection values θ ₁ and θ ₂ are voltage values generated by being generated by eddy current, and are obtained from the inclination detection coils 40 and 41.
[0009]
In the case where the flow rate detector head 15 and without the inclined with respect to molten metal surface 100a, the magnetic flux phi _1, phi ₂ of the, generated by the exciting coils 4 as shown in Figure 10, the dotted line in FIG. 11 As shown by the solid line, it changes depending on the state of inclination of the core 5, and under the state of inclination 1, horizontal and reverse inclination 2, inclination 1 is | φ ₁ |> | φ ₂ |, and horizontal is | φ ₁ | = | φ ₂ | and slope 2 are | φ ₁ | <| φ ₂ |, each state is detected by the tilt detection coils 40 and 41, the difference is detected by the bridge circuit 200, and the above-described gradient is set to always be zero. The operation of the adjustment motor 27 is configured to be feedback-controlled.
[0010]
Next, the operation will be described. First, when the flow rate detector head 15 and the molten metal surface 100a of the conductive fluid 100 are smooth, the distance between the bottom surface of the flow velocity detector head 15 and the molten metal surface 100a, that is, the gap 20 is the same at any point. The magnetic fluxes φsa and φsb generated by the eddy current formed on the upstream side and the downstream side of the flow of the conductive fluid 100 act on the detection coil 6 in directions to cancel each other, and the difference between the magnetic fluxes φsa and φsb is detected. Is done. Note that φ ₁ and φ ₂ are exciting magnetic fluxes.
However, the gap between the bottom surface of the flow velocity detector head 15 and the molten metal surface 100a, such as in the case where the molten metal surface 100a is inclined when the flow velocity detector head 15 is installed or when the molten metal surface undulates due to the flow, When 20 differs, the difference between the magnetic fluxes φsa and φsb increases, and the eddy current component voltage es also increases. Further, when the molten metal surface shape continuously changes, the eddy current component voltage es also changes. Conventionally, the eddy current component voltage es is subjected to signal processing for phase rectification and separation from the electromotive voltage e. However, the signal processing is not completely separated / removed, and remains and becomes a large disturbance when detecting the flow velocity.
[0011]
Therefore, in the present invention, in order to stabilize the eddy current component voltage es generated by the difference between the magnetic fluxes φsa and φsb generated by the eddy current which is the cause of the disturbance, as described above, the flow rate detector is formed by the respective tilt detection coils 40 and 41. The inclination of the head 15, that is, the core 5 is detected via the above-described bridge circuit 200, and the inclination adjustment motor is adjusted so that the difference between the inclination detection values θ ₁ and θ ₂ from the inclination detection coils 40 and 41 becomes zero. The feedback control is performed such that the inclination posture of the frame body 18 always keeps a horizontal state, that is, the flow velocity detector head 15 becomes parallel to the molten metal surface 100a via the projection piece 28 and the inclination adjustment jig 25. By doing so, the eddy current component voltage es can be stabilized, and the accuracy of detecting the finally obtained flow velocity V can be improved as compared with the related art.
[0012]
【The invention's effect】
Since the non-contact flow velocity detecting method and device according to the present invention are configured as described above, the following effects can be obtained.
That is, the inclination of the flow velocity detector head is detected by a pair of inclination detection coils, and the inclination of the flow velocity detector head is adjusted so that the inclination detection value of each inclination detection coil becomes zero, that is, the difference between the eddy current voltages becomes zero. Is controlled by a tilt adjustment motor or the like, so that the flow velocity detector head can always adjust the tilt with respect to the flow direction of the molten metal surface, reducing the fluctuation of the eddy current component voltage which has fluctuated conventionally, and improving the detection accuracy. Can be improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a non-contact flow velocity detecting device according to the present invention.
FIG. 2 is a detailed configuration diagram showing a main part of FIG. 1;
FIG. 3 is an enlarged configuration diagram of a main part of FIG. 1;
FIG. 4 is an enlarged detailed configuration diagram of a main part of FIG. 1;
FIG. 5 is a schematic explanatory view showing the operation of FIG. 4;
FIG. 6 is an enlarged bottom view of the flow velocity detector head of FIG. 1;
FIG. 7 is an enlarged side view showing a coil of the flow velocity detector head shown in FIG. 1;
FIG. 8 is a configuration diagram showing the coil of FIG. 7;
9 is a configuration diagram of a bridge circuit connected to the tilt detection coil of FIG.
FIG. 10 is an explanatory diagram of a state of inclination with respect to the coil of FIG. 8;
FIG. 11 is an explanatory diagram showing a relationship between a molten metal surface and a core.
FIG. 12 is a configuration diagram showing a conventional non-contact flow velocity detecting device.
FIG. 13 is a diagram showing a flow velocity detection characteristic of a conventional method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Low frequency oscillator 2 High frequency oscillator 4 Excitation coil 5 Core 15 Flow velocity detector head es Eddy current component voltage ev Velocity component voltage 16 Detector main body 18 Frame 19 Sensor mounting base 20 Lifting motor 22 Holding spring 25 Inclination adjusting jig 27 Inclination Adjusting motors 40, 41 Tilt detecting coils θ ₁ , θ ₂ Tilt detection value 100 Conductive fluid

Claims (2)

Two alternating currents from the low-frequency oscillator (1) and high-frequency oscillator (2) are applied to the excitation coil (4) of the core (5) placed in a non-contact manner with respect to the conductive fluid to be measured. The low-frequency magnetic field and the high-frequency magnetic field generated by the magnetic field coil (4) are incident on the conductive fluid (100), and the vortex generated by interlinking the magnetic flux generated in the direction obstructing the low-frequency magnetic field generated by the magnetic field coil (4). Current component voltage (es), and a velocity component voltage (ev) generated by relative movement of the low-frequency magnetic field from the magnetic field coil (4) and the conductive fluid (100) to be measured are detected. the non-contact velocity detection method to obtain the flow velocity (V) of the conductive fluid using the flow rate detector head having a sensing coil (6) (15) (100), said flow rate detector head (15) Having a sensor mounting base (19) , the sensor mounting base (19) is provided movably up and down, and is attached to the detector body (16) . A frame member (18) provided to be tiltable, a holding member (23) fixed to the detector main body (16) and passing through a hole (18b) in a bottom portion (18a) of the frame member (18) ; A holding spring (22) provided between the holding member (23) and the bottom portion (18a) to constantly urge the frame body (18) downward, and engages with the bottom portion (18a) and tilt the detector mounting portion of the main body (16) (24) by the tiltable tilt adjustment jig (25), provided in the motor mount (26) of said detector body (16) with forming a shaped The flow velocity detector head (15) using an adjustment motor (27) and a protruding piece (28) that is provided on the inclination adjustment motor (27) so as to be freely retractable and tilts the inclination adjustment jig (25 ). The inclination of the flow velocity detector head (15) is detected by at least one pair of inclination detection coils (40, 41) provided at the lower part of each, and each inclination detection value from each of the inclination detection coils (40, 41) ( theta _1, wherein the inclination such that the difference theta ₂₎ is zero Non-contact velocity detecting method characterized by controlling the inclination and orientation of the flow rate detector head (15) by adjusting motor (27). Two alternating currents from the low-frequency oscillator (1) and high-frequency oscillator (2) are applied to the excitation coil (4) of the core (5) placed in a non-contact manner with respect to the conductive fluid (100) to be measured When the low-frequency magnetic field and the high-frequency magnetic field generated by being incident on the conductive fluid (100), the magnetic flux generated in the direction obstructing the low-frequency magnetic field generated by the magnetic field coil (4) interlinks. The generated eddy current component voltage (es) and the velocity component voltage (ev) generated by the relative movement of the low-frequency magnetic field from the magnetic field coil (4) and the conductive fluid (100) to be measured are detected. In a non-contact flow velocity detecting device configured to obtain a flow velocity (V) of the conductive fluid (100) using a flow velocity detector head (15) having a detection coil (6) for performing the flow velocity detector head (15). Yusuke at least one pair of tilt detection coil provided below the 15) (40, 41), said flow rate detector head (15) Sensor mount (19), said sensor mount (19) is the detector body (16) to tiltably provided a frame body with provided vertically movable (18), said detector body (16) the frame body is provided between the bottom of the frame is fixed (18) and the pressing member (23) passing through the hole (18b) of (18a), the said bottom and the pressing member (23) and (18a) to A holding spring (22) for constantly biasing (18) downward, an L-shape engaged with the bottom (18a) and tilted by a mounting part (24) of the detector body (16). A free tilt adjustment jig (25) , a tilt adjustment motor (27) provided on a motor mount (26) of the detector body (16) , and a tilt adjustment motor (27) provided so as to be freely retractable. wherein a protruding piece for tilting the tilt adjusting jig (25) (28), the conductive via the tilt adjustment jig (25) and the frame (18) by the inclination adjusting motor (27) The flow rate detector head (15) for the ionic fluid (100 ) A non-contact outflow detection device, characterized in that it is configured to adjust the inclination of the outflow.

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