JPS5822922A - Molten metal level gauge by microwave - Google Patents

Abstract

PURPOSE:To measure a distance between a molten metal surface and an antenna with high accuracy even in case when a place being in the vicinity of the molten metal surface is narrow, by using a dielectric rod antenna for a transmitting and receiving antenna. CONSTITUTION:A transmitting and receiving antenna 3 is formed by attaching a tapered dielectric rod 3b to the tip of a waveguide 3a, and is constituted of small size, comparing with a horn antenna or a parabolic antenna. Accordingly, even in case when a place being in the vicinity of a molten metal surface is narrow, a distance between the molten metal surface and the antenna is measured with high accuracy.

Description

Detailed Description of the Invention The present invention has a microwave bridge consisting of a reference side and a measurement side, and the distance and displacement of the molten metal surface, which is the object to be measured, on the measurement side are kept constant by a phase comparison method. Microphone
IIm Financing Dissimilar Metal Level Gauge - Sui 0 This type of conventional (Qw microwave molten metal level gauge) had the drawback of a narrow measurement range, so the applicant first solved that drawback. Patent application for microwave displacement needle 1986-9519
This is proposed by No. 1. This microwave displacement needle has a microwave bridge consisting of a reference side and a measurement side, and is a microwave displacement meter in which the displacement of the object to be measured on the measurement side is fixed by a phase comparison method, and the amount of phase shift is 2K. It is equipped with a counter that adds up the number of times each time it exceeds 15K, and achieves the intended purpose of determining high-precision wILK and a wide range of 15K III. These methods can be achieved using a horn antenna or a parabolic antenna, which is commonly used in
Because the dimensions of the antenna are large, it is difficult to install it in a narrow space such as in a small continuous casting mold.
In order to obtain a directivity of about 3C with a circumference tILa of the G& band size, the dimensions shown in FIGS. 1 and 2 are required, for example. The size of the opening is determined by the size of the horn antenna 1 (1st N
! ! 2) Hiro 50×70 snow, parabon antenna 2 (
Figures 1 and 2) will result in 100 ■ φllf 0 With this method, if you use the same antenna for transmitting and receiving, but if you use separate antennas, you will need twice as much antenna installation space. becomes.

Furthermore, if sharper directivity is required, the size of the antenna increases in inverse proportion to the directivity, making installation in a narrow space increasingly difficult.

Microwave level gauges are originally effective on the needle side in adverse environments, but for the reasons mentioned above, they are difficult to use in confined spaces, such as when measuring the level of hot water in small continuous casting molds. The reality is that there is still no solution to this problem.

The present invention was devised in view of this situation, and it is possible to control the level of the molten metal or its displacement even in a narrow space such as in the case of a small continuous casting mold where the scooping range is wide and wide. In other words, the present invention provides a microwave bridge consisting of a reference side and a measurement side, and a phase shift amount exceeding 2K. 6111 A microwave molten metal level meter that measures the distance or displacement of an object on a constant side using a phase comparison method, is equipped with a counter that adds up the number of times, and is equipped with a cone on an antenna for transmitting and receiving microwaves. This is a book that uses antennas.

Embodiments of the present invention will be described below based on the inner surface. Radio waves are radiated from the tapered portion 3b in the longitudinal direction of the 0 rod, which is constructed by connecting the St body rod 6b with a taper at the tip under an excessive matching condition, and exhibits the function of the turtle antenna and 1.7. As is clear from this figure, compared to the size of the horn antenna 1 and the parabolic antenna 20, this antenna 3 has a circular or elliptical cross section and is nine times smaller.

For example, if directivity is required in the 10G & band, the dimensions of this antenna 3 are 13mm φ x 193mm, which is clearly seen when compared with the dimensions of the conventional example shown in @Figure 1 and Figure 2 It is small.

Also, since the directivity of this antenna 30 is determined by the length of the tapered part and has nothing to do with its cross-sectional area, it is necessary to change the length of Kf-1 in order to obtain the required directivity, but the cross-sectional area does not need to be changed.

For this reason, if there is a set space width of 50 to 40 W@degrees, it becomes possible to measure the level of the molten metal.By the way, regarding the issue of heat resistance, the dielectric material that makes up the wire and antenna has high heat resistance. This can be solved using ceramics. Furthermore, since antenna 3 originally has a small bar shape, 8
As shown in FIG. 4, heat countermeasures can be completed by arranging a cooling tube 4 around the outer periphery of the antenna 5 and blowing cooling air 5.

Therefore, in cases where the antenna must be placed near the nozzle, such as in the case of small-scale continuous casting molds, the antenna can be protected from radiation heat and radiant heat from the hot water surface, and microwaves from the nozzle surface can be protected. It is possible to prevent the effects of unnecessary reflections.

lIl! 5 is an overall block diagram of the microwave molten metal water level gauge according to the above embodiment of the present invention. In the figure, 6 is a mold, 7 is an immersion nozzle, 11 is a microwave oscillator, 12 is a wire directional coupler, 16 is a transmitting antenna, 14 is a hot water surface which is the object to be measured, and 15 is a receiver Antenna, 16 frequency converter, 17 detector, 18
A phase difference detection circuit 119 that detects the phase difference between the measurement side 21 and the reference side 22 is a counter, 20 is a distance calculation circuit,
Reference numeral 23 is a reference oscillator for frequency conversion. Here, the transmitting antenna 1'5 and the receiving antenna 15 are third cone antennas. In this embodiment, the transmitting antenna and the receiving antenna are separate, but it goes without saying that the same antenna may be used for both purposes. In the molten metal level gauge 26, the microwave ray directional coupler 12 of the frequency fo generated from the microwave oscillator 11 is connected to the transmitting antenna 1.
3 to the target object 14 , where it is reflected and returns to the receiving antenna 15 , and a reference side 22 that goes toward the frequency conversion circuit 16 . At the reference side 22, the frequency fs (fo > h) of the reference oscillation gain 23 is subtracted from the frequency fo by the frequency converter 16, and this subtracted frequency (fa-f+) is given to the detector 17. Here, of course, the frequency fo and the frequency fl (f.

10f1) may be applied to the detector 17.

On the measuring side 21, if the distance R between the transmitting/receiving value antenna 13.15 and the object to be measured 14 changes, the path to reach the detector 17 also changes.
If the signals from 2 and measurement side 21 are subjected to i-xing and then passed through a bandpass filter, the phase difference between both sides appears between paths 24 and 25 as information on the frequency of fl, which is easy to measure. Phase difference detection circuit 1 detects 0 phase difference between 24 and 25.
8, as shown in Figure 6, the distance @R from the transmitting/receiving antenna 13.15 to the object to be measured 14 causes a discontinuous change in units of λ4, and the phase difference due to Measurement possible The counter 19 counts up when the output of the phase difference detector 18 returns from 2 to 0.
→ Since the circuit performs a countdown when returning to 2K, the count number n also increases as the distance R increases as shown in FIG. 6(B).

Therefore, if the distance calculation circuit 20 calculates the following equation, the hot water level distance R can be obtained.

1 on the right side of the above equation! The n3 term L. is the value at the measurement starting point and is a constant term, so it does not affect the measurement error. The 21st Jl is a term based on the phase comparison method, and if microwaves with a frequency of 10G& are used, ±a I w O measurement accuracy can be obtained.

In the first term, λ (wavelength of the microwave) can be measured with an accuracy of 5 digits, so if the measurement is performed using a microwave with a frequency of 910G&, a measurement accuracy of ±0.1- can be obtained. Figure 1147 shows the output of the distance calculation circuit 20 in relation to the actual hot water level distance. As is clear from this figure, an output with excellent linearity is obtained.

In the above-described embodiment, the case where the distance between the hot water surface and the antenna, that is, the hot water surface distance R is calculated, was explained. However, in order to calculate the displacement ΔR of the hot water surface distance, the distance calculation circuit 20 should calculate the following formula C n・λ λ・e ΔB, −−+ −−L・ (2) 2
4π As is clear from the above explanation, the microphone a according to the present invention
According to the wave molten metal level gauge, by inserting it into the calculation circuit of the counter 19, it is possible to measure at a high degree over a wide range.Furthermore, by making the transmitting and receiving antenna cone-shaped, the antenna design Even in narrow spaces where space is not available, measurements can be taken at the location.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an enlarged antenna, Fig. 2 is an explanatory diagram of a rabona antenna, Fig. 3 is an explanatory diagram of an antenna of a water level gauge according to the M1 example of the present invention, An explanatory diagram of an antenna of a water level gauge according to another embodiment of the present invention, FIG. 5 is a block diagram of the entire hot water level side according to the above embodiment of the present invention, and FIG. 5- Counter operation explanation 1, 7th
The figure is an output characteristic diagram of the hot water level gauge shown in FIG. 1...Horn antenna, 2...Parabona antenna,
3... Cone antenna, 4... Cooling tube, 5...
Cooling air, 11...Microwave oscillator, 12...
・Directional coupler, 13... Transmission antenna, 14...
Object to be measured, 15... Receiving antenna, 16... Frequency converter, 17... Detector, 18... Phase difference detector, 19... Counter, 20... Distance calculation circuit, 2
DESCRIPTION OF SYMBOLS 1...Microwave measurement side, 22...Microwave reference side, 23...Reference oscillation circuit, 26...Microwave melted maple surface needle. Agent Patent Attorney Tadashi Sato Figure 3, Figure 4, Figure 5, Figure 6, Figure 77;
Display of the case Patent application No. 56-1204+51 No. 2・Name of the invention! Ikuha aim metal hot water plan 3, relationship with the case of the person making the amendment Name of the applicant for the tatami license (412) Nippon Kokan Co., Ltd. 4, agent 6, subject of amendment 'S River use d;:i', +i7 ( 1) Amend the specification O and claims by adding a separate sheet. ) Amend the statement as follows. Equipped with a microwave bridge consisting of a reference side and a measurement side, and a kakunta that adds up the number of times each time the amount of phase shift exceeds 2π, it is possible to calculate the distance of 7 distances of a fixed object on the measurement side or its displacement. A microwave molten metal water level gauge measuring p by a phase comparison method, characterized in that a dielectric rod antenna is used as a microwave transmitting and receiving antenna.

Claims (1)

[Claims] Equipped with a microwave bridge consisting of a reference side and a measurement side, and a counter that adds up the number of times the amount of phase shift exceeds two stomachs, the distance of the object to be measured on the measurement side or its displacement is determined using a phase comparison method. 17 Microwave molten metal level gauge characterized in that a cone antenna is used as an antenna for transmitting and receiving microwaves.