JPS6031010A - Apparatus for measuring thickness of solidified cast piece - Google Patents

Abstract

PURPOSE:To measure the thickness of a solidified cast piece highly accurately, by performing statistical processing of a received electromagnetic ultrasonic wave signal, and removing the signal having abnormal waveforms. CONSTITUTION:Based on the transmission pulse of an electromagnetic ultrasonic wave from a pulse generating circuit 8 and the received signal of the electromagnetic ultrasonic wave through a gate circuit 11, the transmitting time of the ultrasonic wave through a steel piece 7 is measured by a transmitting-time measuring circuit 12. The repeated measured values are stored in a memory part of the transmitting-time operating circuit 22. Whether the stored contents are effective or not is determined by the judged result from an abnormal waveform removing circuit 23 based on the comparison of the result of the statistical processing of the amplitude and the wavelength of the received signal from the gate circuit 11 and a preset value. The average value of the effective stored contents is applied to a solidified thickness operating circuit 15. The abnormal waveform signal generated by randum noises and the like is removed by the statistical processing. Thus the thickness of the solidified cast piece is measured highly accurately.

Description

[Detailed Description of the Invention] The present invention is a device (hereinafter referred to as "shell door side") that measures the solidification thickness of a slab during continuous casting using electromagnetic ultrasonic waves.
It is related to.

A conventional device of this type is shown in FIG. In the figure, (1) is an electromagnetic ultrasonic generator, (2) is an electromagnetic ultrasonic receiver, (7) is a slab, and (8) is a pulse generation circuit.

(9) is the excitation power supply, (II is the amplifier, ('υ is the gate circuit, α is the transmission time measurement circuit, (II is the surface thermometer)
θa) is the slab total thickness measuring device, ([ω is the solidification thickness calculation circuit, (1) is the output circuit. On the other hand, Fig. 1-1 shows the principle. In this figure, (3) is an electromagnetic ultrasonic generation coil, (4) is an electromagnetic ultrasonic detection coil, (5) is an excitation coil for generating a magnetic field, and (6) is an electromagnetic ultrasonic detection coil. ) is a magnetic core for forming a magnetic circuit.Here, a detection coil (4) is a magnetic core for forming a magnetic circuit.
) is connected to amplifier H.

Next, the operation will be explained. The generator coil (3) to which the pulse signal is energized by the pulse generator circuit (8) has an arrow a? around the coil. ), and this pulsed magnetic field is generated according to Lenz's law.
An electromotive force is induced on the surface of the eddy current ttn. This eddy current Ql further generates a pulsed electromagnetic force due to interaction with the pulsed magnetic field indicated by the arrow (17) according to Fleming's left-hand rule, which causes ultrasonic vibrations on the surface of the slab (7). The above is the principle of electromagnetic ultrasound generation.

Next, the electromagnetic ultrasonic waves generated on the surface of the slab (7)
) advances in the direction of the middle arrow alO, and when it reaches the other surface, vibration = byc is generated on the surface of the slab (7). An electromotive force is generated on the surface of the LSI piece (7) due to the interaction between this vibration and the magnetic field created by the excitation coil (5) excited by the excitation power source (9). This is due to Fleming's right-hand rule. This electromotive force causes an eddy current (to) on the surface of the hook (7).
The magnetic field created by this eddy current induces an electromotive force in the detection coil (4) according to Lenz's law.

This electromotive force signal is amplified as a received signal by an amplifier, a necessary portion on the time axis is removed by a gate circuit a0, and is sent to a transmission time measuring circuit I. In this gate circuit Uυ, a time gate is normally created based on the pulse output timing signal of the pulse generating circuit.

Next, in the transmission time measurement circuit 112, the ultrasonic wave is transmitted from the - side of the slab (7) to the other side of the back side (6) based on the time difference between the reception signal input from the gate circuit αD and the pulse output timing signal. Please estimate the time t required.

The resulting signal is sent to the solidification thickness calculation circuit α.

Now, suppose that there is an unsolidified part left in the slab.

If the thickness of the already solidified part is d-d1+r12, then the thickness of the unsolidified part should be D-d, so the speed at which the ultrasonic wave propagates through the solidified part is V, and the unsolidified part is If gc is the propagation speed of the ultrasonic wave, and Vt is the propagation speed of the ultrasonic wave, then the transmission time t for the ultrasonic wave to pass through the entire iron piece is given by D-dt=□mo□■svt. In general, ■ is calculated from the temperature dependence of the ultrasonic propagation velocity according to the average temperature of the solidified part, which is determined by the average or weighted average from the solidification temperature of the slab and the surface temperature measured by two surface thermometers, depending on the steel type. It was, and ■6
Since the unsolidified portion is considered to be in a supercooled state, the value determined experimentally for the ultrasonic propagation velocity in this state is used.

Therefore, in addition to the transmission time, the thickness information from the total thickness measuring device a (a) and 1 are input to the solidification thickness calculation circuit Q clause.
The surface temperature information from the surface thermometer α moat, the solidification temperature value of the slab determined by the steel type, and the ultrasonic propagation velocity Vt in the unsolidified part
If this is obtained, the solidified thickness d can be calculated from the above relational expression. The calculated solidification thickness d is output to the output circuit (I6)
Q is displayed or recorded.

Since the conventional slab solidification thickness measuring device is configured as described above, it is not possible to exclude accidental noise such as external noise from entering the detection coil side of the electromagnetic ultrasonic receiver. However, it has the disadvantage that it is processed as a received signal as it is, resulting in erroneous judgments (erroneous measurements).

This invention was made to eliminate these drawbacks, and by excluding abnormal waveform signals caused by the above-mentioned noise, etc., and by adding statistical processing, it is possible to obtain castings with extremely high measurement accuracy. The present invention provides a piece solidification thickness measuring device.

FIG. 3 is a diagram showing an embodiment of the present invention.

In FIG. 3, (1) is an electromagnetic ultrasonic generator, (2) is an electromagnetic ultrasonic receiver, (7) is a slab, and (8) is a pulse generation circuit.

(9) is an unexcited power supply, (l [is an amplifier, al) is a gate circuit, H is a transmission time measurement circuit, (2 side is a transmission time calculation circuit, (2 East is an abnormal waveform removal circuit, (1) is a surface thermometer,
a◇ is the total slab thickness measuring device, a is the solidification thickness calculation circuit, θ
0 is an output circuit.

FIG. 4 is a diagram showing the circuit configuration of the abnormal waveform removal circuit and the transmission time measurement circuit. In Figure 4, 04
) is a 4-conversion circuit, and (c) is a waveform storage circuit.

00 is the maximum amplitude point detection circuit, and 0η is the maximum value storage circuit.

(Incorporated) is a timing control circuit, CI is a zero loss point detection circuit, and function is a wavelength calculation circuit #C11) is an extreme point detection circuit.
0 is an extreme value storage circuit, (to) is an amplitude ratio calculation circuit, (b) is a wavelength condition judgment circuit, (c) is an amplitude condition judgment circuit,
C (61 and (41) are constant setting circuits, (3D is a waveform information storage circuit.

C3I is a wavelength average value calculation circuit, ■ is an amplitude average value calculation circuit, (1 [ is a comparison judgment circuit, (42) is a transmission timing signal, (43) is a reception signal, and (44) is a transmission time signal.

(45) is a data valid signal, (46) is a transmission time storage circuit, (47) is a valid data determination circuit, (4B) is an average value calculation circuit, and (49) is an average transmission time signal.

Next, the operation of an embodiment of the present invention shown in FIGS. 3 and 4 will be described. The pulse generation circuit (8) outputs a transmission timing signal (42) synchronized with the transmission signal to the stain magnetic wave generator (1), and the transmission time measurement circuit a'
Input to IJ and abnormal waveform removal circuit. On the other hand, the received signal (43) from the electromagnetic ultrasonic receiver (2), which is excited by the excitation power source (9) and becomes receivable, is sent to the amplifier a.
The signal is amplified by @, time-discriminated by the gate circuit Mil11, and inputted to the transmission time measurement circuit 0 and the abnormal waveform removal circuit 3).

Transmission time measurement 11. f, (l, from the time difference between the transmission timing signal (42) and the reception signal (45),
The transmission time tTk is determined, and this is used as the transmission time signal (44) in the transmission time calculation circuit c! - Transfer to the transmission time memory circuit (
46).

Now, in the abnormal waveform removal circuit Q3, the received signal (43
) is first input to the 4 conversion circuit e24, sampled at the timing instructed by the timing control circuit (c), converted to a digital value, and stored in the waveform storage circuit (c) in time series. The circuit (a is interlocked with the transmission timing signal (42).

Timing control is performed so that the entire waveform of the received signal (43) is sufficiently stored.

FIG. 5 shows an example of the received signal (46) stored in the waveform storage circuit (c) as described above.

Note that in FIG. 5, the waveform is shown as an analog waveform.

In reality, it is stored as digital values arranged in chronological order. When the storage of the received signal (43) is completed, the data is sequentially read out according to instructions from the timing control circuit (to), and is then read out by the maximum amplitude point detection circuit (c).

A time tM giving the maximum amplitude is detected, and at the same time, the amplitude value vM at this time is stored in the maximum amplitude value storage circuit. Note that the waveform storage circuit (c) stores data in chronological order, and data sampling is also performed at known timings predetermined by the timing control circuit (2). Therefore, the above-mentioned time tM can be easily determined by knowing the position of the data stored in the waveform storage circuit (c).

Next, when one time tM is detected by the maximum amplitude value recording circuit 2, this information is input to the timing control circuit (c).

The timing control circuit (c) sequentially reads data from the position on the waveform storage circuit (a) corresponding to time 1 to Cross time t2 ~
12, local maximum value, local minimum value = 22, respectively, are detected by the zero cross 22 point detection circuit 0I and the extreme value point detection circuit Oυ. In the wavelength calculation circuit (to), from the above zero cross time,
For example, one wavelength is calculated from 1''''121 to z-2. Of course, when calculating the wavelength λ, we need 2, for example, λ=(
λ −λ 10λ −λ )/2 as 1 −2 2 −
1 as a function of tz s tZ # tz jtz .

-2-112 Other statistical calculation techniques may also be introduced.

The extreme value storage circuit 0 stores the values of -22 amplitude values V, -2 to 7p2 at each extreme point t-1P detected by the extreme value point detection circuit 0υ, and is used as an amplitude ratio calculation circuit. 0■ is the amplitude value 7 stored in the maximum value storage circuit (5) mentioned above.
1--2~2). Mochirun, this amplitude ratio is ・V
Other arithmetic processing may be performed, such as forming a "tri" longer than M.vP-2 to v2.

The wavelength condition determination circuit (b) determines whether the wavelength λ calculated by the wavelength calculation circuit is within the range preset by the constant setting circuit (to), and detects data that does not satisfy this condition. Remove. Do the same.

The amplitude condition judgment circuit (to) is a constant setting circuit (to) where 2 is the amplitude ratio k2 to which is requested by the amplitude ratio calculation circuit (to).
Data is determined to be discarded or discarded depending on whether preset conditions are satisfied. Therefore, constant setting circuit (7)
Only data that satisfies the setting conditions described above passes through all six wavelength condition determination circuits (b) and six amplitude condition determination circuits, and is stored in the waveform information storage circuit 07).

If the process up to this point is repeated for N times of reception.

In the waveform information storage circuit 0θ, among the N wavelength data, there are only (≦N) wavelength data λ1 (1=1 to K) and amplitude ratio data that satisfy the above-mentioned determination condition.

When the N times of reception are completed, the data stored in the waveform information storage circuit 0η are sequentially read out according to the instructions from the timing control circuit Q, and the wavelength average value calculation time IIV1 (
) and amplitude average value calculation circuit G.

0 average value 2・kP-2~kP27% calculated 1・
Comparison and judgment circuit (sent to 40).

The timing control circuit (c) includes a wavelength average value calculation circuit (to) and an amplitude average value calculation circuit G! 1 sends each average value to the comparison/judgment circuit (41), reads out the data in the wavelength information storage circuit (c3) again, and further compares it with the comparison column (kp) to determine the value set in advance by the constant setting circuit (41). A data valid signal (45) is output only for data that falls within the deviation value.

Here, among the times 0 transmission time 2-T, ("'"1~N)O stored in the transmission time storage circuit (46),
The transmission time (47) corresponding to the data valid signal (45)
), the average value calculation circuit (48) calculates the transmission time calculation circuit, and sends it as an average transmission time signal (49) to the coagulation thickness calculation circuit (t51).

In the solidification thickness calculation circuit 00, the average transmission time 1-1. From the temperature T measured by the surface thermometer (c) and the total thickness D measured by the slab total thickness measuring device A4,
Calculate the solidification thickness in the same way as the conventional calculation method, and calculate the output circuit (
10) is output to the outside.

In this embodiment, the setting value of the constant setting circuit (to) is set to be, for example, ±10% with respect to the wavelength and amplitude ratio expected in advance, and the setting value of the constant setting circuit (to) is set to be, for example, ±10%. By setting it to ±3, short wavelength waveforms with steep rises caused by inrush currents of motors and electromagnetic 1::1 circuits can be very effectively removed without losing useful data.

In addition, although the explanation above has been made using a digital circuit that handles digitized data, it is of course possible to replace part or all of this circuit with an analog circuit, or replace it with software using a computer. However, this does not in any way detract from the spirit of the present invention. In addition, in this embodiment, the extreme value point and zero cross point are respectively t p −j
P #22 1 -1 was explained as 8 points, but the present invention is not limited to -222, and does not particularly limit the number of extreme points and zero cross points, and within the scope of the gist of the present invention. There are various variations.

Furthermore, the abnormal waveform removal circuit and the transmission time calculation circuit according to the present invention can be applied not only to shell thickness gauges but also to other transmitter/receiver devices 2 that utilize the propagation of ultrasonic waves, such as wall thickness gauges and thermometers.

As described above, according to the present invention, abnormal waveform signals generated due to accidental noise such as foreign noise being mixed into the detection coil side of an electromagnetic ultrasonic receiver are excluded, and further statistical processing is added. By doing so, it is possible to measure the solidified slab thickness with extremely high measurement accuracy.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of a conventional slab solidification thickness measuring device, Figure 2 is a diagram showing the principle of electromagnetic ultrasonic generation and reception, and Figure 3 is a diagram showing the configuration of an embodiment of the device of the present invention. figure,
FIG. 4 is a block diagram showing the circuit configuration of the abnormal waveform removal circuit and the transmission time calculation circuit of the device of the present invention, and FIG. 5 is a diagram showing an example of a received signal obtained by the device of the present invention. In the figure, j+1) is an electromagnetic ultrasonic generator, (2) is an electromagnetic ultrasonic receiver, (3) is an electromagnetic ultrasonic generation coil, (4) is an electromagnetic ultrasonic detection coil, (5) is an excitation coil, and (6) is an electromagnetic ultrasonic wave generator. ) is the magnetic core, (7) is the slab, (8) is the pulse generation circuit, (9) is the excitation power supply, α[ is the amplifier, aυ is the gate circuit, 03 is the transmission time measurement circuit, 0th floor is the surface thermometer, ■ is the slab total thickness measuring device, aS is the solidification thickness calculation circuit, on is the output circuit, α
η is the pulse magnetic field, α and Kan are the eddy currents, a is the propagation direction of the ultrasonic wave, COO is the output of the electromagnetic ultrasonic detection coil (4), Co. is the transmission time calculation circuit, and (c) is the abnormal waveform Elimination circuit, Q→S conversion circuit, (C) waveform storage circuit, @ maximum amplitude point detection circuit, @ maximum value storage circuit, 0 樟 timing control circuit, @ zero cross point detection circuit, (to ) is the wavelength calculation circuit, OI) is the extreme value point detection circuit, 0' is the extreme value storage circuit, (C) is the amplitude ratio calculation circuit, (F) is the wavelength condition judgment circuit, (C) is the amplitude condition judgment circuit , (7) and (
41) is a constant setting circuit, t3n is a waveform information storage circuit,
(to) is a wavelength average value calculation circuit, C31 is an amplitude average value calculation circuit, 00 is a comparison judgment circuit, (42) is a transmission timing signal, (43) is a reception signal, (44) is a transmission time signal, (45) is a data valid signal, (46) is a transmission time storage circuit, (47) is a valid data judgment circuit t
(48) is an average value calculation circuit. (49) is the average transmission time signal. Note that in FIG. 1, the same parts are indicated by the same reference numerals. Agent Masuo Oiwa Tokukai Sho GO-31010 (6)

Claims (1)

[Scope of Claims] An electromagnetic ultrasonic generator that is installed on one surface of a continuously cast slab and includes a coil to which a high-frequency pulse current is applied and generates ultrasonic waves on the surface of the slab; an electromagnetic ultrasonic receiver including a detection coil installed on the other surface to receive the ultrasonic wave; Ultrasonic generation of the above ultrasonic generator and receiver. a time measuring circuit that measures the time t required for the ultrasonic wave to propagate from the - side to the other side of the slab from the timing of reception; a total thickness measuring device that measures the total thickness D of the slab; and a total thickness measuring device that measures the total thickness D of the slab; The time t measured by the measurement circuit, the total thickness p measured by the total thickness measuring device, the speed at which the ultrasonic wave propagates through the solidified part of the slab with a thickness d, and the thickness D - d of the slab. In the slab solidification thickness measuring device, the apparatus comprises: a calculation circuit that calculates the solidified part thickness d from the speed at which the ultrasonic waves propagate in the unsolidified part; A slab solidification characterized in that an abnormal waveform removal circuit is provided between the electromagnetic ultrasonic receiver and the time measurement circuit for the purpose of performing statistical processing on the signal and excluding abnormal waveform signals. Thickness measuring device.