阅读说明：本技术 一种线圈自激励的铁磁性管道电磁超声换能器、激发装置和接收装置 (Coil self-excited ferromagnetic pipeline electromagnetic ultrasonic transducer, excitation device and receiving device ) 是由 王晓红 杨嘉欣 黄超 于 2019-10-15 设计创作，主要内容包括：本发明公开一种线圈自激励的铁磁性管道电磁超声换能器、激发装置和接收装置,包括：骨架、正相线圈组、反相线圈组。该电磁超声换能器通过一种特殊波形的激励电流,在待测铁磁性管道内激发脉冲磁场的同时,自动生成外加的偏置磁场。正相线圈组和反相线圈组所产生交替分布的磁致伸缩效应满足超声波相长干涉的匹配关系,从而在铁磁性管道中激励出沿轴向传播的电磁超声纵向导波。本发明还公开了使用该换能器的电磁超声激发装置和电磁超声接收装置。本发明公开的电磁超声换能器无需设置直流线圈和交流线圈,结构更简单,对应的激发装置和接收装置,也无需使用刚性永磁铁来提供偏置磁化场,减小了装置的体积。(the invention discloses a coil self-excited ferromagnetic pipeline electromagnetic ultrasonic transducer, an excitation device and a receiving device, which comprise: skeleton, normal phase coil assembly, reverse phase coil assembly. The electromagnetic ultrasonic transducer automatically generates an external bias magnetic field while exciting a pulse magnetic field in a ferromagnetic pipeline to be detected through an exciting current with a special waveform. The alternating distributed magnetostriction effect generated by the normal-phase coil group and the reverse-phase coil group meets the matching relation of ultrasonic constructive interference, so that the electromagnetic ultrasonic longitudinal guided wave propagating along the axial direction is excited in the ferromagnetic pipeline. The invention also discloses an electromagnetic ultrasonic excitation device and an electromagnetic ultrasonic receiving device using the transducer. The electromagnetic ultrasonic transducer disclosed by the invention does not need to be provided with a direct current coil and an alternating current coil, has a simpler structure, is provided with a corresponding excitation device and a corresponding receiving device, does not need to use a rigid permanent magnet to provide a bias magnetization field, and reduces the volume of the device.)

1. A coil self-excited ferromagnetic conduit electromagnetic ultrasonic transducer comprising: a framework (1), a normal phase coil group (2) and a reverse phase coil group (3),

the framework (1) is a hollow cylindrical pipe made of insulating materials, the inner diameter of the hollow cylindrical pipe is slightly larger than the outer diameter of the ferromagnetic pipeline to be tested, and the hollow cylindrical pipe is coaxially sleeved on the outer surface of the ferromagnetic pipeline to be tested, 2n annular wire grooves (4) are formed in the upper surface of the framework (1) at equal intervals, the interval between the wire grooves (4) is 1/2 of the wavelength of the excited ultrasonic waves, n is related to the number of the excited electromagnetic ultrasonic pulses and is 3 ~ 10;

the normal phase coil group (2) is formed by connecting n normal phase coils in series, wherein the normal phase coils are annular coils with equal turns and are wound in odd ~ numbered wire slots (4) of the framework (1), and n is 3 ~ 10;

the reverse phase coil group (3) is formed by connecting n reverse phase coils in series, n is 3 ~ 10, the reverse phase coils are annular coils and are wound in wire grooves (4) of the framework (1) in even numbers, the reverse phase coils and the normal phase coils are wound in the same direction, and the number of turns of the reverse phase coils is equal to that of the normal phase coils.

2. a coil self-excited ferromagnetic conduit electromagnetic ultrasonic transducer as claimed in claim 1, wherein the excitation of the positive phase coil set (2) and the negative phase coil set (3) is direct pulse current when used as the excitation end; the direct current pulse current comprises direct current bias current and sine pulse fluctuation, and the amplitude of the sine pulse fluctuation is smaller than the direct current bias current; the direct current bias current acted on the excitation of the positive phase coil group (2) and the direct current bias current acted on the excitation of the reverse phase coil group (3) are in the same direction; and the phase difference between the sine pulse wave phase acted on the excitation of the positive phase coil group (2) and the sine pulse wave phase acted on the excitation of the negative phase coil group (3) is 180 degrees.

3. a coil self-excited ferromagnetic conduit electromagnetic ultrasonic transducer as claimed in claim 1, wherein the excitation of the positive phase coil set (2) and the negative phase coil set (3) is a dc bias current in the same direction when acting as a receiving terminal.

4. A coil self-excited ferromagnetic conduit electromagnetic ultrasonic excitation device, comprising: an electromagnetic ultrasonic transducer (5), a high-power constant current source (6), a pulse signal source (7), an inverter (8), a normal-phase power amplifier (9), an inverse-phase power amplifier (10) and an isolation capacitor,

the electromagnetic ultrasonic transducer (5) is a ferromagnetic pipeline electromagnetic ultrasonic transducer with a self-excited coil as claimed in claim 1, and is mounted on a ferromagnetic pipeline to be tested;

the high-power constant current source (6) generates two paths of direct current bias current outputs with the same size and direction; the first path of output is connected with a normal phase coil group (2) of the electromagnetic ultrasonic transducer (5), and the second path of output is connected with an inverse phase coil group (3) of the electromagnetic ultrasonic transducer (5);

the pulse signal source (7) generates sine pulse signals, the number of pulses of the sine pulse signals is 3 ~ 8, the output of the pulse signal source (7) is divided into two paths, the first path of output is connected with the input end of the positive phase power amplifier (9), and the second path of output is connected with the input end of the reverse phase power amplifier (10) after passing through the phase inverter (8);

The isolation capacitor (11) is an electrodeless capacitor and is used for isolating direct current bias current so as to prevent the output of the high-power constant current source (6) from causing current reverse flow to the positive-phase power amplifier (9) or the reverse-phase power amplifier (10);

The output of the positive phase power amplifier (9) passes through an isolation capacitor (11) and then is connected with a positive phase coil group (2) of the electromagnetic ultrasonic transducer (5); the peak current output by the positive phase power amplifier (9) is less than the direct current bias current of the high-power constant current source (6);

the output of the inverting power amplifier (10) passes through another isolation capacitor (11) and then is connected with an inverting coil group (3) of the electromagnetic ultrasonic transducer (5); the peak current output by the inverting power amplifier (10) is smaller than the direct current bias current of the high-power constant current source (6).

5. a coil self-excited ferromagnetic conduit electromagnetic ultrasound receiving device, comprising: an electromagnetic ultrasonic transducer (5), a high-power constant current source (6), a coupling capacitor (12), a signal conditioning circuit (13), an acquisition circuit (14) and an upper computer (15),

the electromagnetic ultrasonic transducer (5) is a ferromagnetic pipeline electromagnetic ultrasonic transducer with a self-excited coil as claimed in claim 1, and is mounted on a ferromagnetic pipeline to be tested;

The high-power constant current source (6) generates two paths of direct current bias current outputs with the same size and direction; the first path of output is connected with a normal phase coil group (2) of the electromagnetic ultrasonic transducer (5), and the second path of output is connected with an inverse phase coil group (3) of the electromagnetic ultrasonic transducer (5);

The input end of the signal conditioning circuit (13) is connected with the positive phase coil group (2) or the negative phase coil group (3) of the electromagnetic ultrasonic transducer (5) through a coupling capacitor (12) and is used for acquiring electromagnetic ultrasonic signals transmitted in the pipeline;

The input end of the acquisition circuit (14) is connected with the output end of the signal conditioning circuit (13) and is used for converting the electromagnetic ultrasonic signals into digital signals; the output end of the acquisition circuit (14) is connected with an upper computer (15) through a data bus and is used for uploading the digitized ultrasonic signals to the upper computer (15) for processing.

Technical Field

the invention relates to the field of electromagnetic ultrasonic guided wave detection technology and equipment, in particular to an electromagnetic ultrasonic transducer applied to ferromagnetic pipelines, which can be used for nondestructive detection of defects of ferromagnetic pipelines such as iron pipes, steel pipes and the like.

Background

With the rapid development of the energy industry such as natural gas and petroleum, pipeline transportation has the advantages of high efficiency, low loss, low cost and the like, and is increasingly emphasized by the industrial field, and the pipelines are mainly ferromagnetic pipelines. However, ferromagnetic pipelines have weak corrosion resistance and are prone to crack, corrosion and other defects under severe working conditions in the pipelines. If the defects cannot be checked and disposed in time, further pipeline leakage and explosion can be caused, and huge economic loss and casualties are caused.

Among various nondestructive testing technologies, the electromagnetic ultrasonic testing technology has the characteristic of non-contact, can excite ultrasonic waves on the surface of a metal material, and is high in testing speed and convenient to use. At present, the electromagnetic ultrasonic detection technology is widely applied to the fields of petrifaction, high-speed rail, aviation, aerospace and the like.

In the electromagnetic ultrasonic detection technology, two effects of generating electromagnetic ultrasonic are as follows: lorentz force effect and magnetostriction effect. For ferromagnetic materials, the effect of the magnetostrictive effect is more prominent, so in ferromagnetic pipelines, the magnetostrictive effect is mostly used to excite ultrasonic waves. The electromagnetic ultrasonic transducer generates a magnetostrictive effect in the ferromagnetic material by radiating a pulse magnetic field outwards and the composite action of the pulse magnetic field and the external magnetic field.

Chinese patent CN 103616441 a discloses an electromagnetic ultrasonic signal excitation device for ferromagnetic materials. The ultrasonic signal of separating longitudinal wave from transverse wave can be excited by adopting the transduction mechanism of electromagnetic ultrasonic, and the ultrasonic signal is used for online detection of tiny defects in the ferromagnetic material sheet. An electromagnet is used for providing a magnetic field, an electromagnetic ultrasonic transduction mechanism is taken as a technical core, and excited Lorentz force and magnetostrictive force are orthogonally decomposed.

Chinese patent CN104122330B discloses a pipeline defect detection method based on electromagnetic ultrasonic longitudinal guided waves, which comprises arranging a plurality of ring magnets coaxially arranged with the pipeline to generate a radial static magnetic field on the surface of the pipeline; solenoid coils are coaxially sleeved on two sides of each loop magnet array, so that circumferential induction eddy current is generated in the pipeline to be detected; under the combined action of the circumferential induced eddy current and the radial static magnetic field, longitudinal mode guided waves are excited. In the invention, a plurality of groups of permanent magnets are needed, and the current directions of a plurality of solenoid coils are different, so that generated eddy currents are easy to interfere with each other.

chinese patent CN 108088907A discloses an electromagnetic ultrasonic-based high-temperature pipeline damage online monitoring system, which can quickly scan the distribution situation of defects in a pipeline at a longer distance and can install a transducer and a hardware circuit system on the pipeline for a long time; the heat of the pipeline is converted into electric energy through a thermoelectric conversion circuit, and the system is powered when the system works; a large amount of data can be accumulated, and the sensitivity of the system and the reliability of results are improved through comprehensive analysis of the data.

however, the electromagnetic ultrasonic transducer used for detecting the pipeline defects at present mainly has the following defects: firstly, the electromagnetic ultrasonic transducer is mainly excited by adopting a Lorentz force effect, and the online pipeline is mostly a ferromagnetic pipeline, so that the efficiency of ultrasonic excitation is not high; secondly, the electromagnetic ultrasonic transducer adopts a rigid magnet to provide a bias magnetic field, and the probe is large in size and is not suitable for the requirements of miniaturization and portability of the electromagnetic ultrasonic transducer for pipeline defect detection.

Disclosure of Invention

In order to solve the above problems, the present invention provides a ferromagnetic conduit electromagnetic ultrasonic transducer with a self-excited coil. The transducer does not need a strong magnet to provide a static magnetic field or a direct current coil to form an electromagnet, and can automatically generate an additional bias magnetic field while exciting a pulse magnetic field in a ferromagnetic pipeline to be detected through exciting current with a special waveform. A bias magnetic field and a pulse magnetic field formed by self excitation of the coil generate a magnetostrictive effect on the wall of the ferromagnetic pipeline and form electromagnetic ultrasonic longitudinal guided waves.

In order to achieve the purpose, the invention adopts the following technical scheme:

A coil self-excited ferromagnetic conduit electromagnetic ultrasonic transducer comprising: a framework, a normal phase coil group and a reverse phase coil group, wherein,

the framework is a hollow cylindrical pipe made of insulating materials, the inner diameter of the hollow cylindrical pipe is slightly larger than the outer diameter of the ferromagnetic pipeline to be detected, the hollow cylindrical pipe is coaxially sleeved on the outer surface of the pipeline, 2n annular wire grooves are formed in the upper surface of the framework at equal intervals, the interval between the wire grooves is 1/2 of the wavelength of the excited ultrasonic wave, n is related to the number of the excited electromagnetic ultrasonic pulses, and can be 3-10 generally.

the normal phase coil group is formed by connecting n normal phase coils in series, wherein n can be 3 ~ 10 generally, the normal phase coils are annular coils, the number of turns of each normal phase coil is equal, and the normal phase coils are wound in odd number wire grooves of the framework;

the reverse phase coil group is formed by connecting n reverse phase coils in series, n can be 3 ~ 10 generally, the reverse phase coils are annular coils and are wound in even ~ number wire grooves of the framework, the reverse phase coils and the normal phase coils are wound in the same direction, and the number of turns of the reverse phase coils is equal to that of the normal phase coils.

When the ferromagnetic pipeline electromagnetic ultrasonic transducer with the self-excited coil is used as an excitation end, excitation of the positive-phase coil group and the negative-phase coil group is direct-current pulse current; the direct current pulse current comprises direct current bias current and sine pulse fluctuation, and the amplitude of the sine pulse fluctuation is smaller than the direct current bias current; further, the direct current bias current acting on the excitation of the positive phase coil assembly and the direct current bias current acting on the excitation of the reverse phase coil assembly are in the same direction; and the phase difference between the sine pulse wave phase acted on the excitation of the positive phase coil group and the sine pulse wave phase acted on the excitation of the negative phase coil group is 180 degrees.

when the ferromagnetic pipeline electromagnetic ultrasonic transducer with the self-excited coil is used as a receiving end, the excitation of the positive phase coil assembly and the negative phase coil assembly is direct current bias current in the same direction.

Another object of the present invention is to provide a ferromagnetic conduit electromagnetic ultrasonic excitation device with self-excitation of coil, comprising: electromagnetic ultrasonic transducer, high-power constant current source, pulse signal source, phase inverter, normal phase power amplifier, reverse phase power amplifier, and isolation capacitor,

the electromagnetic ultrasonic transducer is a ferromagnetic pipeline electromagnetic ultrasonic transducer with a coil self-excited, and is arranged on a ferromagnetic pipeline to be tested;

the high-power constant current source generates two paths of direct current bias current outputs with the same size and direction; the first output is connected with a normal phase coil group of the electromagnetic ultrasonic transducer, and the second output is connected with an inverse phase coil group of the electromagnetic ultrasonic transducer.

the pulse signal source generates sinusoidal pulse signals, the number of the pulses is 3 ~ 8, the output of the pulse signal source is divided into two paths, the first path of output is connected with the input end of the positive phase power amplifier, and the second path of output is connected with the input end of the reverse phase power amplifier after passing through the phase inverter.

The isolation capacitor is an electrodeless capacitor and is used for isolating direct current bias current so as to prevent the output of the high-power constant current source from causing current reverse flow to the positive-phase power amplifier or the negative-phase power amplifier.

The output of the normal phase power amplifier is connected with a normal phase coil group of the electromagnetic ultrasonic transducer after passing through an isolation capacitor; the peak current output by the positive phase power amplifier is smaller than the direct current bias current of the high-power constant current source.

the output of the inverting power amplifier is connected with an inverting coil group of the electromagnetic ultrasonic transducer after passing through another isolating capacitor; the peak current output by the inverting power amplifier is smaller than the direct current bias current of the high-power constant current source.

When the excitation device works, the normal phase coil group and the reverse phase coil group of the electromagnetic ultrasonic transducer obtain the excitation of direct current bias current in the same direction to form a unidirectional bias magnetization field to axially magnetize the ferromagnetic pipeline. However, in the magnetization process, the excitation of the normal-phase coil assembly also includes sinusoidal pulse fluctuation, so that the ferromagnetic material in the tube wall below the normal-phase coil assembly generates a periodic magnetostriction effect. Similarly, the ferromagnetic material in the tube wall below the phase-reversal coil group generates a magnetostrictive effect with a phase difference of 180 °.

because the center distance between the normal phase coil and the reverse phase coil is 1/2 of the designed ultrasonic wavelength, the magnetostrictive effect generated by the two coil groups meets the matching relation of ultrasonic constructive interference, and electromagnetic ultrasonic longitudinal guided waves propagating along the axial direction are excited in the ferromagnetic pipeline.

it is still another object of the present invention to provide a ferromagnetic conduit electromagnetic ultrasonic receiving device with self-excitation coil, comprising: an electromagnetic ultrasonic transducer, a high-power constant current source, a coupling capacitor, a signal conditioning circuit, an acquisition circuit and an upper computer, wherein,

The electromagnetic ultrasonic transducer is a ferromagnetic pipeline electromagnetic ultrasonic transducer excited by a coil and is arranged on a ferromagnetic pipeline to be tested;

the high-power constant current source generates two paths of direct current bias current outputs with the same size and direction; the first output is connected with a normal phase coil group of the electromagnetic ultrasonic transducer, and the second output is connected with an inverse phase coil group of the electromagnetic ultrasonic transducer.

The input end of the signal conditioning circuit is connected with a normal phase coil group or a reverse phase coil group of the electromagnetic ultrasonic transducer through a coupling capacitor and is used for acquiring the electromagnetic ultrasonic signals transmitted in the pipeline.

The input end of the acquisition circuit is connected with the output end of the signal conditioning circuit and is used for converting the electromagnetic ultrasonic signals into digital signals; the output end of the acquisition circuit is connected with an upper computer through a data bus and is used for uploading the digitized ultrasonic signals to the upper computer for processing.

when the receiving device works, the normal phase coil group and the reverse phase coil group of the electromagnetic ultrasonic transducer obtain the excitation of direct current bias current with the same direction, and a unidirectional bias magnetization field is formed to axially magnetize the ferromagnetic pipeline. When the ultrasonic wave propagates to the lower part of the normal phase coil group or the reverse phase coil group, the reverse magnetostriction effect is generated under the action of the bias magnetization field, and a voltage signal corresponding to the ultrasonic wave, namely an ultrasonic wave signal, is induced in the normal phase coil group or the reverse phase coil group.

The invention has the beneficial effects that: the invention provides a ferromagnetic pipeline electromagnetic ultrasonic transducer with a self-excited coil, which applies direct current pulse current to a positive phase coil group and a negative phase coil group, and generates a periodic magnetostriction effect with alternately distributed phases while generating a bias magnetization field. Therefore, in the electromagnetic ultrasonic transducer, a direct current coil and an alternating current coil are not required to be arranged, and the structure is simpler. The excitation device and the receiving device do not need to use a rigid permanent magnet to provide a bias magnetization field, so that the volume of the device is reduced.

Drawings

FIG. 1 is a schematic axial sectional view of a first embodiment of the present invention;

FIG. 2 is a comparison of excitation current waveforms when used as an excitation terminal according to an embodiment of the present invention;

FIG. 3 is an axial cross-sectional structural view of the magnetization field distribution at time T1 in accordance with one embodiment of the present invention;

FIG. 4 is an axial cross-sectional structural view of the magnetization field distribution at time T2 in accordance with one embodiment of the present invention;

FIG. 5 is a block diagram of the second embodiment of the present invention;

FIG. 6 is a block diagram of a third embodiment of the present invention;

Reference numbers for the various components in the figures: 1. a framework; 2. a normal phase coil group; 3. an inverting coil group; 4. a wire slot; 5. an electromagnetic ultrasonic transducer; 6. a high-power constant current source; 7. a pulse signal source; 8. an inverter; 9. a positive phase power amplifier; 10. an inverting power amplifier; 11. an isolation capacitor; 12. a coupling capacitor; 13. a signal conditioning circuit; 14. an acquisition circuit; 15. an upper computer; 16. and (5) testing the ferromagnetic pipeline.

Detailed Description

The present invention will be further described with reference to the following specific embodiments. These examples are intended to illustrate the invention and are not intended to limit the scope of the invention.