CN114371221B

CN114371221B - Electromagnetic ultrasonic transducer with ultra-high temperature resistant double-coil structure

Info

Publication number: CN114371221B
Application number: CN202210023555.2A
Authority: CN
Inventors: 王淑娟; 李茜; 葛宇航; 梁宝
Original assignee: Harbin Institute of Technology
Current assignee: Harbin Institute of Technology
Priority date: 2022-01-10
Filing date: 2022-01-10
Publication date: 2023-10-03
Anticipated expiration: 2042-01-10
Also published as: CN114371221A

Abstract

An electromagnetic ultrasonic transducer with an ultra-high temperature resistant double-coil structure belongs to the technical field of electromagnetic ultrasonic nondestructive detection, and the specific scheme is as follows: the electromagnetic ultrasonic transducer comprises a water cooling system and a probe assembly, wherein the water cooling system comprises an outer shell and an inner shell which are integrally connected, a cavity is reserved between the outer shell and the inner shell, a water inlet and a water outlet are formed in the upper surface of the cavity, the water inlet and the water outlet are communicated with a water tank through water pipes, a water pump is arranged on the water pipe connected with the water inlet, a groove I is formed in the bottom of the outer shell upwards, the probe assembly comprises an exciting coil and an eddy current coil, the eddy current coil is arranged in the groove I, the exciting coil is arranged inside the inner shell, and the central axes of the exciting coil and the eddy current coil coincide. The invention can work for a long time in the environment of 1000 ℃, realizes real-time monitoring of the detected object, improves the high temperature resistance of the EMAT probe, and is suitable for the fields of high temperature metal material detection and the like.

Description

Electromagnetic ultrasonic transducer with ultra-high temperature resistant double-coil structure

Technical Field

The invention belongs to the technical field of electromagnetic ultrasonic nondestructive detection, relates to an electromagnetic ultrasonic transducer, and in particular relates to an electromagnetic ultrasonic transducer with an ultrahigh temperature resistant double-coil structure.

Background

The metal is an important material and is widely applied to the industries of aerospace, shipbuilding, petrochemical industry and the like. In many industries, it operates at high temperatures, including metallurgical manufacturing, power generation, and the like. It is therefore necessary to detect the metallic material at high temperatures. In the industrial operation and production process, it is important to timely detect defects and damages generated in the production and processing process by using a nondestructive detection means; continuous monitoring is carried out at high temperature, so that the time and economic loss caused by shutdown can be avoided, the cost is reduced, and the enterprise benefit is maximized; meanwhile, by analyzing the historical data obtained by continuous monitoring, the service life of the product can be predicted and early-warned, so that the quality of the product is ensured, and the production efficiency is improved.

Currently, piezoelectric ultrasound, laser ultrasound and electromagnetic ultrasound are commonly used for the measurement of metallic materials at high temperatures. Piezoelectric transducers under high temperature conditions lack a suitable high temperature couplant to achieve good coupling between the sample and the transducer. Although the transducer can be arranged on the waveguide rod, the coating of the coupling agent is avoided, and the high-temperature measurement is realized, the ultrasonic signal is introduced into the ultrasonic signal by the arrangement mode of the waveguide rod. On the other hand, laser-ultrasonic systems for measuring and detecting metals are expensive, complex in structure and sensitive to environmental changes. Compared with the two technologies, the electromagnetic ultrasonic transducer (EMAT) is a non-contact, low-cost and simple-to-operate ultrasonic transducer. Therefore, the method is widely applied in the fields of monitoring and evaluation, thickness measurement, defect detection and the like.

The electromagnetic ultrasonic echo method is utilized to realize the monitoring of the metal material in the high-temperature environment, and the design of the EMAT is a key link for carrying out high-temperature nondestructive detection on the metal material by utilizing the echo method. The EMAT-based high-temperature detection structure mainly comprises a permanent magnet structure and a pulse electromagnet structure. The permanent magnet EMAT consists of a permanent magnet and a coil. The working temperature range of the existing permanent magnet EMAT is about 500 ℃ at most. Electromagnetic iron core EMAT is often adopted for the pulse electromagnet. The permanent magnet and the iron core have the problem of demagnetization in the ultra-high temperature environment, which limits the temperature range of the application of the high-temperature EMAT. To avoid the problem of demagnetization, it is common practice to add a cooling system or to avoid high temperature damage to the EMAT assembly by taking short measurements of the test piece. However, electromagnetic ultrasonic transducers have the problem of low transduction efficiency, and increased lift-off can result in lower signal-to-noise ratios; if the design of the cooling system is unreasonable, the EMAT structure is more complex, and the portability is reduced; when short-time measurement is utilized, the temperature of the sample does not reach a steady state, so that the sound velocity measurement result is inaccurate, and in many occasions, the measured object needs to be monitored for a long time. The working range of the existing pulse electromagnet ultra-high temperature EMAT is about 700 ℃. The existing active cooling EMAT probes are based on water cooling structures with permanent magnets or iron cores, the whole volume is large, the signal to noise ratio in a high-temperature environment is low, and the temperature is still not up to 1000 ℃. At present, the failure of the high temperature EMAT probe to monitor echo signals at higher temperatures mainly has two reasons: the high temperature resistance of the sensor probe is poor, the high temperature insulation cannot be ensured due to the overhigh temperature, and the probe is easy to damage; the signal-to-noise ratio of the echo signal detected by the designed sensor probe is low, and the echo signal gradually decays with the rise of temperature, so that the echo signal cannot be detected at higher temperature.

Disclosure of Invention

The invention aims to solve the problems of low temperature and poor signal-to-noise ratio in a high-temperature environment of the existing EMAT suitable detection occasion and provides an electromagnetic ultrasonic transducer with an ultrahigh-temperature-resistant double-coil structure.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

the utility model provides an electromagnetic ultrasonic transducer of super high temperature resistant double coil structure, includes water cooling system and probe subassembly, water cooling system includes external shell body and the interior casing of body coupling, leave the cavity between external shell body and the interior casing, the cavity upper surface is provided with water inlet and delivery port, water inlet and delivery port all communicate with the water tank through the water pipe, are provided with the water pump on the water pipe of connecting the water inlet, the bottom of external shell body upwards is provided with recess I, the probe subassembly includes exciting coil and vortex coil, vortex coil sets up in recess I, exciting coil sets up the inside of casing including, exciting coil and vortex coil's axis coincidence.

Further, the eddy current coil comprises a ceramic plate, a lead I and a shielding layer, wherein a groove II is formed in the ceramic plate, the projection of the groove II in the overlooking direction is of a spiral groove structure which bypasses from inside to outside, the lead I is wound in the groove II, and the shielding layer is placed on the upper surface of the ceramic plate.

Further, the wire I wound in the groove II is two layers, and the two layers of wires I are integrally connected at the center of the coil.

Furthermore, the exciting coil is a hollow multi-layer coil formed by winding a lead II, and each layer of coil is wound for a plurality of turns.

Further, a heat insulation layer is arranged between the exciting coil and the inner shell.

Further, a channel is downwards arranged on the bottom surface of the inner shell, and the channel is communicated with the bottom surface of the groove I.

Further, the electromagnetic ultrasonic transducer further comprises a top cover, the top cover is fixedly connected with the inner shell, a lead port is formed in the top end of the top cover, and leads of the exciting coil and the eddy current coil are led out from the lead port.

Further, the outer diameter of the exciting coil is 45mm, and the inner diameter is 25mm.

Further, the wire diameter of the exciting coil is 2mm, and the wire diameter of the eddy current coil is 0.1mm.

Furthermore, the outer shell and the inner shell are made of nonmagnetic stainless steel.

Compared with the prior art, the invention has the beneficial effects that:

the invention adopts the EMAT with the double-coil structure, and the exciting coil does not contain an iron core structure, so that the iron core is prevented from being influenced by environmental factors to limit the working temperature range of the EMAT.

The exciting coil and the eddy current coil are provided with reliable high-temperature insulation protection measures, and the method is different from the prior art in that: the water cooling system of the invention can not only cool the exciting coil, but also cool the eddy current coil. The method avoids the damage of the eddy current coil caused by high temperature by increasing the lifting distance, reduces the lifting distance to a certain extent, and reduces the problem of low signal-to-noise ratio of the ultrasonic signal caused by the increase of the lifting distance.

The probe assembly has the advantages that the probe assembly is protected from high temperature damage by high temperature insulation protection measures and the design of a water cooling system structure, and can realize ultra-high temperature continuous monitoring within the temperature range of 1000 ℃, and compared with the existing EMAT probe, the probe assembly has a higher temperature detection range.

Drawings

FIG. 1 is a schematic diagram of an electromagnetic ultrasonic transducer with an ultra-high temperature resistant dual-coil structure;

FIG. 2 is an enlarged view of the bottom of the electromagnetic ultrasonic transducer;

FIG. 3 is a schematic perspective view of a probe assembly;

FIG. 4 is a front view of the probe assembly;

FIG. 5 is a top view of the probe assembly;

FIG. 6 is a schematic diagram of an ultrasonic echo method monitoring;

FIG. 7 is a timing diagram of an electromagnetic ultrasonic transducer, wherein a is excitation current, b is alternating pulse current, and c is ultrasonic echo;

FIG. 8 is an echo signal plot of carbon steel;

in the figure, 1, an outer shell, 2, an inner shell, 3, a cavity, 4, a water pipe, 5, a water tank, 6, a water pump, 7, an excitation coil, 8, an eddy current coil, 9, a heat insulation layer, 10, a top cover, 11, a tested block, 12, a heating unit, 21, a groove I, 22, a channel, 31, a water inlet, 32, a water outlet, 101 and a lead wire opening.

Detailed Description

The invention will now be described in detail with reference to figures 1-8 and the accompanying examples.

Detailed description of the preferred embodiments

The utility model provides an electromagnetic ultrasonic transducer of super high temperature resistant double coil structure, includes water cooling system and probe subassembly, as shown in fig. 1 and 2, water cooling system includes outer casing 1 and inner casing 2 of an organic whole connection, outer casing 1 and inner casing 2 are cylindrical staving structure, leave cavity 3 between outer casing 1 and inner casing 2 lateral wall and the bottom, cavity 3 upper surface one end is provided with water inlet 31, and the other end is provided with delivery port 32, water inlet 31 and delivery port 32 all communicate with water tank 5 through water pipe 4, are provided with water pump 6 on water pipe 4 of connection water inlet 31, the bottom of outer casing 1 upwards is provided with recess I21, the probe subassembly includes exciting coil 7 and vortex coil 8, vortex coil 8 is fixed to be set up in recess I21, and the bottom keeps the parallel and level with the bottom of outer casing 1, exciting coil 7 is fixed to be set up in the inside of inner casing 2, exciting coil 7 and vortex coil 8's axis coincidence, preferably, outer casing 1's diameter is 85mm, highly is 100mm; the diameter of the water pipe 4 is 8mm, and the water pump 6 and the water tank 5 are used for ensuring normal running of cold water in the water cooling system and cooling the probe assembly.

Further, the eddy current coil 8 comprises a ceramic plate, a lead I and a shielding layer, a groove II is formed in the ceramic plate, projection of the groove II in the overlooking direction is a spiral groove structure which bypasses from the center to the outer edge, the lead I is wound in the groove II to prevent turn-to-turn short circuit, high-temperature insulation is achieved, and the shielding layer is placed on the upper surface of the ceramic plate. Preferably, the ceramic plate is circular, the diameter is 20mm, the thickness is 0.2mm, the distance between two adjacent circles of grooves II is 0.1mm, the wire I is a copper wire coated with a high-temperature-resistant insulating layer, the wire diameter of the wire I is 0.1mm, the shielding layer is circular, the diameter is 20mm, the material is tin foil 3M AB6005GHF, the thickness is 0.2mm, and the shielding layer is used for shielding the influence of exciting coil eddy current on eddy current coil receiving signals. The height of the groove I21 is 0.4mm, the eddy current coil 8 is fixedly arranged inside the groove I21 by means of high-temperature glue, and the bottom of the eddy current coil 8 is just flush with the bottom of the outer shell 1.

Further, the exciting coil 7 is a hollow multi-layer coil wound by a wire II, and each layer of coil is wound for a plurality of turns. The outer diameter of the exciting coil 7 is 45mm, and the inner diameter is 25mm. Preferably, the number of the coil layers of the exciting coil 7 is 4, each layer is wound for 4 turns, the wire II is a copper wire coated with a high-temperature insulating layer, and the wire diameter of the wire II is 2mm, as shown in fig. 3-5.

Further, a heat insulation layer 9 is arranged between the exciting coil 7 and the inner shell 2, and the heat insulation layer 9 can prevent the exciting coil 7 from being damaged by a high-temperature environment to a certain extent due to the fact that the heat insulation layer 9 is arranged.

Further, a channel 22 is provided downwards on the bottom surface of the inner housing 2, the channel 22 is in communication with the bottom surface of the groove i 21, and the purpose of the channel 22 is to guide out the lead wire of the eddy current coil 8.

Further, the electromagnetic ultrasonic transducer further comprises a top cover 10, the top cover 10 is fixedly and hermetically connected with the inner shell 2, a lead port 101 is formed in the top end of the top cover 10, leads of the exciting coil 7 and the eddy current coil 8 are led out from the lead port 101, the leads of the exciting coil 7 are connected with exciting signals, the leads of the eddy current coil 8 are connected with exciting signals, and the top cover 10 is designed to lead out the leads of the exciting coil 7 and the eddy current coil 8 to a position far away from a heat source.

Furthermore, the outer shell 1 and the inner shell 2 are made of nonmagnetic stainless steel, so that the interference of the outer shell material on echo signals can be avoided.

When the electromagnetic ultrasonic transducer is used, the tested block 11 is arranged on the heating unit 12, the heating unit 12 can heat the tested block 11, and the eddy current coil 8 is placed on the upper surface of the tested block 11 to detect the tested block 11.

Based on an ultrasonic echo method, an experimental schematic diagram of continuous monitoring of the electromagnetic ultrasonic transducer with the ultra-high temperature resistant double-coil structure, which is designed according to the invention, on the tested block 11 within the temperature range of 1000 ℃ is shown in fig. 6.

A complete ultrasonic excitation reception process is subjected to twice the thickness of the block under test 11, so that the echo sound velocity measurement can be expressed as

v＝2d/t

Where d is the thickness of the block 11 to be tested and t is the time for completing the ultrasonic excitation receiving process.

The working principle of the designed electromagnetic ultrasonic transducer with the ultra-high temperature resistant double-coil structure is as follows: when the eddy current coil 8 on the surface of the metal material is supplied with high-frequency pulse current of 4-8 cycles, eddy current with corresponding frequency can be generated in the skin depth of the metal surface. When an excitation current acts on the metal surface through a quasi-static magnetic field generated by the excitation coil 7, eddy currents and magnetic field effects generate forces, and in non-ferromagnetic materials, only lorentz forces act to generate ultrasonic signals, and in ferromagnetic materials, acoustic waves are generated by lorentz forces, magnetization forces and magnetostriction effects. When the static magnetic field is perpendicular to the sample surface, shear waves are mainly generated. When the static magnetic field is parallel to the sample surface, longitudinal waves are mainly generated. The current sequence of the electromagnetic ultrasonic transducer with the ultra-high temperature resistant double-coil structure is shown in fig. 7. The reception of the ultrasonic wave is the inverse of the generation process. When ultrasonic waves propagate to the surface of the metal material, the particles vibrate to cut magnetic induction lines of a static magnetic field, and alternating current is generated on the surface of the metal. Then, an alternating current generates induced electromotive force in the coil, and the induced electromotive force is processed by a circuit to obtain an echo signal.

The specific detection steps are as follows: after the ultra-high Wen Lici coil 7 and the eddy current coil 8 are installed, the leads of the double coils are connected out from the lead port 101 and are connected with a host control circuit. The heating unit 12 is set to a required temperature, the tested block 11 is placed in a heating furnace of the heating unit 12, the EMAT probe with the ultra-high temperature resistant double-coil structure is placed on the tested block 11, the water pump 6 is started, cold water in the water tank 5 starts to circulate in the cavity 3 of the probe, the temperature of the probe assembly is reduced, and the purpose of long-term monitoring is achieved.

The thickness of the high-temperature metal can be monitored by using the measured ultrasonic echo signals, and the sound velocity and attenuation law of the ultrasonic echo signals obtained in a high-temperature environment can be researched to analyze the changes of the metal material along with the temperature changes, such as the material characteristics and the like. It should be noted that: when calculating the sound velocity of the ultrasonic echo, the sound velocity needs to be corrected by taking the thermal expansion factor into consideration.

Example 1

Because the excitation magnetic field is mainly in the horizontal direction, the excitation coil 7 and the eddy current coil 8 are combined to generate transverse waves, 45# steel is used as a measured object, and the feasibility of the ultra-high temperature resistant EMAT water cooling system is verified.

The experiment sets the heating furnace to heat to the appointed temperature for 20 minutes, after the heat preservation is carried out for twenty minutes, echo signals are acquired for the tested block 11, the echo signals obtained by the experiment result are shown in fig. 8, the temperature in the drawing refers to the temperature in the furnace chamber, and the temperature of the tested block 11 is slightly lower than the temperature in the furnace chamber, because the water cooling system can locally cool the tested block 11. Experiments show that the probe of the electromagnetic ultrasonic transducer with the ultra-high temperature resistant double-coil structure can work for a long time in the environment of 1000 ℃, so that the real-time monitoring of the tested block 11 is realized, the high temperature resistance of the EMAT probe is improved, and the electromagnetic ultrasonic transducer is suitable for the fields of high temperature metal material detection and the like.

The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An electromagnetic ultrasonic transducer with an ultra-high temperature resistant double-coil structure is characterized in that: including water cooling system and probe subassembly, water cooling system includes external shell (1) and internal shell (2) of body coupling, leave cavity (3) between external shell (1) and internal shell (2) lateral wall and the bottom, cavity (3) upper surface is provided with water inlet (31) and delivery port (32), water inlet (31) and delivery port (32) all communicate with water tank (5) through water pipe (4), are provided with water pump (6) on water pipe (4) of connecting water inlet (31), the bottom of external shell (1) upwards is provided with recess I (21), the probe subassembly includes exciting coil (7) and vortex coil (8), vortex coil (8) set up in recess I (21), exciting coil (7) set up the inside of internal shell (2), the axis coincidence of exciting coil (7) and vortex coil (8), water cooling system is simultaneously to exciting coil and vortex coil water-cooling.

2. The electromagnetic ultrasonic transducer of claim 1, wherein: the eddy current coil (8) comprises a ceramic plate, a lead I and a shielding layer, wherein a groove II is formed in the ceramic plate, the projection of the groove II in the overlooking direction is of a spiral groove structure which bypasses from inside to outside, the lead I is wound in the groove II, and the shielding layer is placed on the upper surface of the ceramic plate.

3. An electromagnetic ultrasonic transducer according to claim 2, characterized in that: the wire I wound in the groove II is two layers, and the two layers of wires I are integrally connected at the center of the coil.

4. The electromagnetic ultrasonic transducer of claim 1, wherein: the exciting coil (7) is a hollow multi-layer coil formed by winding a lead II, and each layer of coil is wound for a plurality of turns.

5. The electromagnetic ultrasonic transducer of claim 1, wherein: a heat insulation layer (9) is arranged between the exciting coil (7) and the inner shell (2).

6. The electromagnetic ultrasonic transducer of claim 1, wherein: the bottom surface of inner shell (2) is provided with passageway (22) downwards, passageway (22) with the bottom surface intercommunication of recess I (21).

7. The electromagnetic ultrasonic transducer of claim 1, wherein: the electromagnetic ultrasonic transducer further comprises a top cover (10), the top cover (10) is fixedly connected with the inner shell (2), a lead port (101) is formed in the top end of the top cover (10), and leads of the exciting coil (7) and the eddy current coil (8) are led out from the lead port.

8. The electromagnetic ultrasonic transducer of claim 4, wherein: the outer diameter of the exciting coil (7) is 45mm, and the inner diameter is 25mm.

9. The electromagnetic ultrasonic transducer of claim 1, wherein: the wire diameter of the exciting coil (7) is 2mm, and the wire diameter of the eddy current coil (8) is 0.1mm.

10. The electromagnetic ultrasonic transducer of claim 1, wherein: the outer shell (1) and the inner shell (2) are made of nonmagnetic stainless steel.