JPS6026161B2 - Metal pipe wall thickness measurement device using electromagnetic ultrasonic waves - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring uneven thickness of metal tubes using electromagnetic ultrasonic waves.

When hot extruding, drilling, and rolling steel pipes, the wall thickness may not be uniform due to operating conditions such as non-uniform heating, and automatic measurement of the running distance is strongly desired during operating conditions or during inspections between sleeves. .

Up until now, absorption methods using RI and ultrasonic methods have been attempted, but the former method is difficult to handle, and measurement in operational conditions is completely possible using the absorption method. In order to inject ultrasonic waves into a metal tube through contact soot with an ultrasonic vibrator, the surface must be smooth, and there have been attempts to measure at high temperatures through a water column. It was not put into practical use. The present invention generates ultrasonic waves directly in a metal tube through the interaction of electricity and magnetism, converts the ultrasonic waves reflected from the inner wall of the metal tube into a through flow through the interaction with magnetism, and detects the ultrasonic waves. An electromagnetic ultrasonic thickness detection device that detects the thickness of a metal tube based on time is installed so as to rotate around the metal tube to measure uneven thickness of the metal tube. The principle of generating and detecting ultrasonic waves through interaction with electricity and magnetism has been known for a long time, but its efficiency was poor and it was considered impossible to put it into practical use. As a result of devising the method and detection method, it has become possible to obtain an output equal to or twice as high as that of ordinary ultrasonic waves, and an example will be described in detail below. FIG. 1 is a schematic diagram showing the principle of measuring the thickness of a high-temperature metal tube using electromagnetic ultrasound.

When an iron core 3 is placed in the vicinity of a magnetic field coil 2 near a metal tube 1 and a voltage is applied to the magnetic field coil 2 from a power source 4, a magnetic field 5 as shown by a dotted arrow is generated within the metal tube 1. On the other hand, when a high-frequency pulse current is passed through the ultrasonic generating coil 6 by a high-frequency pulse power source 7, an eddy current 8 is excited by induction in the metal tube 1, and as a result of the interaction between the eddy current 8 and the magnetic field 5, Fleming's left hand The law produces a pulsed kinetic force 9, shown by the arrow. This kinetic force 9 then travels in the direction shown by arrow 10 as an electromagnetic ultrasonic wave. When this electromagnetic ultrasonic wave reaches the inner wall of the metal tube 1, it is reflected and the arrow 11
come back in the direction of When the electromagnetic ultrasonic wave in the direction of arrow 11 reaches near the surface of the material, it produces a kinetic force 12 which, as a result of its interaction with the magnetic field 5, produces eddy currents 13 according to Fleming's right-hand rule. The eddy current 13 is detected by a detection coil 14, amplified and detected by an amplification/detection circuit 15, and a signal having a value equal to or higher than a set value by a slice circuit 16 is sent to a gate circuit 18. Time signal generation circuit 17
The time pulses being generated pass through the gate circuit 18 from the moment the ultrasonic waves are generated until the ultrasonic waves are detected, and are counted by the counting circuit 19. On the other hand, the temperature of the metal tube is automatically or manually given to the sound intensity setting device 20 from the output of the thermometer, and the signal from the sound intensity setting device 20 is given to the temperature/ultrasonic propagation velocity converter 21. , is converted into an ultrasonic propagation velocity signal at the temperature. The ultrasonic propagation velocity signal v from the temperature/ultrasonic propagation velocity converter 21 and the time signal t from the counting circuit 19 are converted into h=
The calculation of v×t is performed, and the thickness h at the temperature at that time is
is calculated and displayed on the display device 23. In addition,
When generating electromagnetic ultrasonic waves, for convenience of explanation, it is assumed that the ultrasonic waves are generated by the interaction between the external magnetic field 5 and the eddy current 8 generated within the conductive material 1. Of course, ultrasonic waves are also generated by the interaction between the magnetic field generated by the high frequency current generated by the electroconductive material 1 and the eddy current 8 induced in the conductive material 1, and an external magnetic field is not necessarily required.

FIG. 2 is a characteristic diagram of temperature and ultrasonic propagation velocity of steel material.

This characteristic diagram was measured using an electromagnetic ultrasonic method using a thin metal wire with a high key point embedded in the pongee groove of alumina porcelain as a coil for ultrasonic generation and detection, and can measure up to 1300 oo. there were. As an iron core, the diameter is 40 m, the length is 140 m, and the supermagnetic force of the coil is 10 m.
000 ampere turn, a magnetic field of Uta G was obtained in the high temperature steel pipe at 1100 pm, and a high frequency pulse power source with voltage 1 of V and capacity of 500 VA was used. When a spark gap equipped with a pair of discharge electrodes and a heat-resistant ultrasonic generation coil were connected in series and discharged, the coil rose for 1 sec and the current 1. A high-frequency pulsed current was generated, and sufficient sensitivity could be obtained.

The propagation speed of transverse ultrasonic waves in a steel pipe at 1100°C is 2350 skin/sec, and when a dish MHZ pulse is generated as a time pulse of the time signal generation circuit 17, the propagation time is 42.8.
428 as the count number by the counting circuit 19 in French sec.
Therefore, the thickness was reduced to 1/2 by the reflection method, and the thickness was displayed as 50.3 on the thickness display, and sufficient measurement accuracy was obtained from the disassembly of the counting circuit 19. FIG. 3 is a schematic diagram showing the principle of a metal pipe thickness unevenness measuring device using an electromagnetic ultrasonic thickness meter.

Around the metal tube 1, an electromagnetic ultrasonic thickness detection device 24 consisting of a magnetic field coil 2, an iron core 3, an ultrasonic generation coil 6, and a detection coil 14 is rotatably mounted on a pedestal 25. The position or angle of the electromagnetic ultrasonic thickness detection device 24 is detected by a position detector 26. The power supply and detection signal to the electromagnetic ultrasonic thickness detection device 24 and the position signal of the position detector 26 are each taken out to the outside by a slip ring or the like, and when the metal tube 1 reaches the measurement position, the electromagnetic ultrasonic thickness detection device 24 Although not shown, it begins to rotate on the pedestal by a motor. A magnetic field is generated by the current from the power source 4, and an ultrasonic wave is generated by the high-frequency pulse current from the high-frequency pulse power source 7.The gap for detecting the thickness is as shown in Figure 1, and the thickness at a certain point is indicated as the thickness. The thickness signal is displayed on the device 23, and the thickness signal is sent to the thickness unevenness display device 27. On the other hand, electromagnetic ultrasonic thickness detection device 2
The position of 4 is detected by the position detector 26, and the yielding layer signal is also sent to the thickness deviation display device 27, where it is combined with the thickness signal and displayed comprehensively by the thickness deviation display device 27. FIG. 4 shows an example of an uneven thickness display record.

The display is a linear display, but a 3600 circular graph display may also be explored. Figure 5 shows the maximum value of the metal pipe wall thickness,
FIG. 3 is a schematic diagram showing the principle of displaying the minimum value and maximum wall thickness deviation.

The wall thickness signal of the metal tube is sent to the thickness display device 2 every time it is measured.
3 to temporary storage devices 28 and 29. The contents of the maximum value storage circuit 30 are set to zero by the signal from the zero return circuit 31 at the start of measurement, and the contents of the temporary storage circuit 28 and the contents of the maximum value storage circuit 30 are compared by the maximum value comparison circuit 32 for each measurement. Only when the contents of the temporary storage circuit 28 are larger than the contents of the maximum value storage circuit 30, the gate circuit 33 becomes an active state, and the contents of the temporary storage circuit 28 are replaced with the contents of the maximum value storage circuit 30. By the above steps,
The signals measured one after another are sent from the thickness display device 23 to the temporary storage circuit 28 and compared by the comparison circuit 32. When the series of measurements is completed, the contents of the maximum value storage circuit 30 become the maximum value of the wall thickness. At the same time, the maximum value display device 34
displayed by. On the other hand, the same process is performed for the minimum value.

That is, the measured value of the thickness display device 23 is stored in the temporary storage device 2.
9, and the contents of the minimum value storage circuit 35 are set to all 9 digits by the signal from the 9th circuit 36 at the start of measurement. For each measurement, the contents of the temporary storage circuit 29 and the minimum storage circuit 35
The contents of are compared by the minimum value comparison circuit 37, and only when the contents of the temporary storage circuit 29 are smaller than the contents of the minimum value storage circuit 35, the gate circuit 38 is opened, and the contents of the temporary storage circuit 29 are compared with the minimum value storage circuit 35. Replaced with the contents of 35. Through the above procedure, the signals measured one after another are sent from the thickness display device 23 to the temporary storage circuit 29, and compared by the comparison circuit 37. When the series of measurements is completed, the minimum value storage circuit 35 records the thickness. is the minimum value of
At the same time, it is displayed by the minimum value display device 39. When the measurement of the maximum value and minimum value is completed according to the above procedure, the contents of the maximum value storage circuit 30 and the minimum value storage circuit 35 are subtracted by the subtraction circuit 40, and the result is displayed on the thickness deviation display device 41.
will be displayed. With this device, it is now possible to measure wall thickness deviations in high-temperature pipes during rolling, and various actions can be taken during operation, resulting in significant results in improving dimensional accuracy and yield.

Of course, measurement at room temperature is also effective, and can bring about great effects in inspections.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the principle of measuring the thickness of high-temperature metal pipes using electromagnetic ultrasound, Figure 2 is a graph showing the relationship between temperature and ultrasonic propagation velocity, and Figure 3 is the principle of the metal pipe thickness unevenness measurement device. Fig. 4 is a graph showing an example of thickness unevenness record, Fig. 5 is an explanatory diagram showing
The figure is a block diagram of the wall thickness deviation display section. 1...Metal tube, 2...Magnetic field coil, 3...
・Iron core, 4...Power supply, 5...Magnetic field, 6
...... Coil for ultrasonic generation, 7... High frequency pulse power supply, 8 Eddy current, 9... Kinetic force, 10...
...Arrow, 11...Arrow, 12...Motor force, 13...Eddy current, 14...Detection coil, 15...Amplification・Detection circuit, 16...
... Slice circuit, 17 ... Time signal generation circuit, 18 ... Gate circuit, 19 ... Counting circuit, 20 ... Temperature setting device, 21.・・・・・・
Temperature/ultrasonic propagation velocity converter, 22... neck calculation circuit,
23... Display device, 24... Electromagnetic ultrasonic thickness detection device, 25... Frame, 26...
Position detector, 27... Thickness unevenness display device, 28...
... Temporary storage device, 29 ... Temporary storage device, 30 ... Maximum value storage circuit, 31 ...
Zero circuit, 32... Maximum value comparison circuit, 33...
Gate circuit, 34... Maximum value display device, 35.
...Minimum value storage circuit, 36...Nineth win, 37...Most 4 value comparison circuit, 38...
・Gate circuit, 39... Minimum value display device, 40
...Subtraction circuit, 41... Thickness unevenness display device. Figure 1 Figure 2 Figure 8 Figure 4 Figure 6

Claims (1)

[Claims] 1. An ultrasonic wave generating coil and a magnetic field generating device are provided for flowing a high frequency pulsed current near the surface of a metal tube, and the high frequency pulsed current flowing through the ultrasonic generating coil is provided alone or separately. Ultrasonic waves are generated in the metal tube through interaction with the magnetic field from the magnetic field generator, and the generated ultrasonic waves reach the inner wall of the metal tube and are reflected, resulting in a vibration force based on the reflected ultrasonic waves and a magnetic field generated by the magnetic field generator. a high-frequency pulse power supply for passing a high-frequency pulse current through the ultrasonic generation coil; an amplification detector for amplifying and detecting the signal current of the detection coil; and the high-frequency pulse. A device that measures the propagation time of ultrasonic waves through the metal tube wall based on the current and signals from the detection coil, a device that calculates and displays the thickness of the metal tube from the propagation time, and a magnetic field generator for ultrasonic generation coils and detection. A pedestal mounting an electromagnetic ultrasonic thickness detection device consisting of a coil, a device for rotating the pedestal around a metal tube, a device for detecting the position of the pedestal, and a device for comprehensively displaying the thickness and measurement position of the metal tube. Metal pipe thickness unevenness measuring device. 2. The device according to claim 1, comprising a device for storing the maximum value of the metal pipe thickness, a device for storing the minimum value, and a device for calculating and displaying the difference between the maximum value and the minimum value. Metal pipe thickness unevenness measuring device.