Small electromagnetic ultrasonic sensor and electromagnetic ultrasonic detection equipment

Abstract

The invention discloses an electromagnetic ultrasonic sensor and electromagnetic ultrasonic detection equipment, the sensor comprises a shell and a sensing assembly, the sensing assembly comprises a magnet and a coil, the magnet comprises a cylindrical magnetic core and an annular magnetic ring surrounding the magnetic core, and the coil is in a concentrically coiled circle shape and is flatly laid below the magnet; in the left side part of the magnetic core, the upper half part is an N pole, the lower half part is an S pole, in the right side part, the upper half part is an S pole, and the lower half part is an N pole; in the left side part of the magnetic ring, the half located on the inner side is an S pole, the half located on the outer side is an N pole, in the right side part, the half located on the inner side is an N pole, and the half located on the outer side is an S pole. The sensor still has enough magnetic field intensity and detection sensitivity under the condition that the size is reduced, and detection operation can still be carried out in a narrow space.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic ultrasonic sensors, and in particular to a small electromagnetic ultrasonic sensor and an electromagnetic ultrasonic detection device. Background Art

[0002] Electromagnetic Acoustic Transducer (EMAT) is a non-contact ultrasonic testing technology that uses electromagnetic principles to excite and receive ultrasonic waves. Compared with traditional contact ultrasonic testing technology, EMAT does not require coupling agents and can achieve long-distance detection. It is especially suitable for detection tasks in high-temperature and high-pollution environments. The working principle of EMAT is based on the Lorentz force and eddy current effect. When a conductive material (usually a metal material) is placed in an alternating magnetic field, eddy currents are generated in the material. These eddy currents will generate a magnetic field in the opposite direction of the external magnetic field. The two magnetic fields interact to form a Lorentz force, which causes the material to vibrate and generate ultrasonic waves. Through the EMAT detection method, non-contact non-destructive detection of defects inside the material, such as cracks and pores, can be performed. However, traditional electromagnetic ultrasonic sensors are large in size and difficult to perform detection operations in a small space. Summary of the invention

[0003] The purpose of the present invention is to overcome the above-mentioned defects or problems existing in the background technology and to provide a small electromagnetic ultrasonic sensor and an electromagnetic ultrasonic detection device, which can perform detection operations in a small space.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] Technical solution 1: An electromagnetic ultrasonic sensor, comprising: a shell, whose lower end is used to form a detection end; a sensor component, which is installed in the shell and includes a magnet and a coil; the magnet includes a cylindrical magnetic core and a ring-shaped magnetic ring surrounding the magnetic core; the coil is a concentrically wound circle and is laid flat under the magnet; a plane where the axis of the magnetic core is located is defined as a first plane, and the first plane divides the magnet into a left part and a right part; in the left part of the magnetic core, the upper half is an N pole and the lower half is an S pole, and in the right part, the upper half is an S pole and the lower half is an N pole; in the left part of the magnetic ring, the inner half is an S pole and the outer half is an N pole, and in the right part, the inner half is an N pole and the outer half is an S pole.

[0006] Technical solution 2 based on technical solution 1: the outer diameter of the coil is consistent with the outer diameter of the magnetic core, and it is centered below the magnetic core.

[0007] Technical solution three based on technical solution two: two layers of coils connected in series are stacked under the magnet.

[0008] Technical solution 4 based on technical solution 3: the lower end of the magnetic ring is flush with the lower end of the magnetic core, and the upper end thereof is higher than the upper end of the magnetic core.

[0009] Technical solution five based on technical solution four: the height difference between the upper end of the magnetic ring and the upper end of the magnetic core is 20% of the length of the magnetic core.

[0010] Technical solution 6 based on technical solution 5: the magnet also includes a copper foil arranged between the magnetic core and the magnetic ring, and the inner and outer sides of the copper foil are respectively adhered to the outer wall of the magnetic core and the inner wall of the magnetic ring.

[0011] Technical solution seven based on technical solution six: the thickness of the copper foil is 8% of the outer diameter of the magnetic core.

[0012] Technical solution eight based on technical solution seven: the difference between the outer diameter and the inner diameter of the magnetic ring is 22% of the outer diameter of the magnetic core, the length of the magnetic ring is 120% of the length of the magnetic core, and the outer diameter of the magnetic core is not less than 10 mm.

[0013] Technical solution nine based on technical solution eight: a buffer layer is provided between the coil and the magnetic core, and the buffer layer is an iron-nickel-cobalt alloy, in which the nickel content is 49%-51%, the iron content is 32%-33%, and the cobalt content is 16%-17%.

[0014] In addition, the present invention also provides technical solution ten: an electromagnetic ultrasonic detection device, which includes a signal generator and a signal processor, and also includes an electromagnetic ultrasonic sensor as described in any one of technical solutions one to nine, and the electromagnetic ultrasonic sensor is electrically connected to the signal generator and the signal processor.

[0015] It can be seen from the above description of the present invention that, compared with the prior art, the present invention has the following beneficial effects:

[0016] Technical solution 1 provides an electromagnetic ultrasonic sensor, which includes a shell and a sensor component. The sensor component is installed in the shell and includes a magnet and a coil. The magnet includes a magnetic core and a magnetic ring. The magnetic ring is arranged outside the magnetic core, and the polarity distribution of the magnetic core and the magnetic ring is specially designed. Due to the polarity configuration of the magnetic core and the magnetic ring, the entire magnet forms a composite magnetic field structure. The magnetic core can generate a longitudinal magnetic field, and the magnetic ring can generate an annular magnetic field surrounding the magnetic core. The cooperation of the two makes the magnetic field in the working area of ​​the sensor more concentrated and uniform, so that the sensor can ensure that the magnetic field still has a high intensity while reducing the volume. At the same time, the coil is concentrically wound in a circle and is arranged under the magnet. This arrangement can match the magnetic field distribution of the coil with that of the magnet, maximize the use of the magnetic field generated by the magnet, and The coil here also plays the role of self-excitation and self-reception, which can excite the detected material to vibrate and form ultrasonic waves, and can receive ultrasonic waves and form induction signals; because the coil is arranged under the magnet and overlaps with the concentrated area of ​​the magnetic field, the coupling loss between the coil and the magnetic field is reduced, and because the magnetic field is confined to a smaller area, the coil does not need to be designed too large to achieve a sufficient induction effect, thereby reducing the space occupied by the coil and reducing the overall volume of the sensor; overall, the sensor improves the sensing component, and these improvements include the structural design of the magnet, the configuration of the polarity on the magnet, and the positional relationship between the coil and the magnet, so that the sensor still has sufficient magnetic field strength and detection sensitivity when the volume is reduced, and detection operations can still be performed in a small space.

[0017] In technical solution two, the outer diameter of the coil is consistent with the outer diameter of the magnetic core, and it is centered below the magnetic core. This arrangement allows the coil to always be in the area with the most concentrated magnetic field, further enhancing the electromagnetic coupling efficiency between the coil and the magnet, reducing magnetic field leakage and invalid sensing areas, and reducing the unevenness of the magnetic field distribution, improving the stability of the signal, and allowing the sensor to achieve better performance in a smaller size.

[0018] In technical solution three, a double-layer coil is laid, which can enhance the sensitivity of electromagnetic induction while reducing the volume. Moreover, since the two coils are connected in series and are both under the magnetic core, the magnetic fields can be superimposed on each other, thereby further enhancing the magnetic field strength of the sensor.

[0019] In technical solution four, the upper end of the magnetic ring is made higher than the upper end of the magnetic core, which can suppress the lift-off signal during the detection process, and can stabilize the sound waves generated by the vibration of the material during the detection process, thereby improving the detection accuracy.

[0020] In technical solution five, the height difference between the upper end of the magnetic ring and the upper end of the magnetic core is limited to 20% of the length of the magnetic core. Under this size limitation, the detection accuracy can be better improved.

[0021] In technical solution six, copper foil is also arranged between the magnetic core and the magnetic ring to isolate the interference of useless magnetic field on the coil and further improve the detection effect.

[0022] In technical solution seven, the thickness of the copper foil is limited to 8% of the outer diameter of the magnetic core. Under this size limit, the copper foil can adapt to the size of the magnetic core and better isolate the useless magnetic field.

[0023] In Technical Solution 8, the difference between the outer diameter and the inner diameter of the magnetic ring is limited, and the length of the magnetic ring and the length of the magnetic core are limited. Under this size limitation, the magnetic core and the magnetic ring of the magnet have a better coordination effect, and can provide a high-intensity magnetic field in a smaller volume, thereby ensuring the detection effect.

[0024] In technical solution nine, a buffer layer made of iron-nickel-cobalt alloy is provided between the coil and the magnetic core, which can improve the stability of the signal and make the magnetic field evenly distributed.

[0025] Technical solution ten provides an electromagnetic ultrasonic detection device, which adopts the above-mentioned electromagnetic ultrasonic sensor and can perform detection operations in a small space. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 A schematic diagram of the structure of the sensor component in the electromagnetic ultrasonic sensor provided in the embodiment of the present invention Figure 1 ;

[0028] Figure 2 A schematic diagram of the structure of the sensor component in the electromagnetic ultrasonic sensor provided in the embodiment of the present invention Figure 2 .

[0029] Description of main reference numerals:

[0030] Sensing component 1; magnet 2; coil 3; magnetic core 4; magnetic ring 5; first plane 6; left part 7; right part 8; copper foil 9; buffer layer 10. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are preferred embodiments of the present invention and should not be regarded as excluding other embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the claims, description and the above-mentioned drawings of the present invention, unless otherwise clearly defined, the use of terms such as "first", "second" or "third" etc. are for distinguishing different objects rather than for describing a specific order.

[0033] In the claims, specification and the above-mentioned drawings of the present invention, unless otherwise explicitly defined, directional words, such as the terms "center", "lateral", "longitudinal", "horizontal", "vertical", "top", "bottom", "inside", "outside", "up", "down", "front", "back", "left", "right", "clockwise", "counterclockwise", etc., indicating directions or positional relationships are based on the directions and positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the specific protection scope of the present invention.

[0034] In the claims, specification and the above drawings of the present invention, unless otherwise clearly defined, if the term "fixed connection" or "fixed connection" is used, it should be understood in a broad sense, that is, any connection method without a displacement relationship and relative rotation relationship between the two, that is to say, including non-detachable fixed connection, detachable fixed connection, integrated connection and fixed connection through other devices or elements.

[0035] In the claims, description and drawings of the present invention, if the terms "include", "have" and their variations are used, they are intended to mean "including but not limited to".

[0036] Example 1

[0037] Reference Figure 1 and Figure 2 The embodiment of the present invention provides an electromagnetic ultrasonic sensor, which can be installed to form an electromagnetic ultrasonic detection device and used to detect surface defects and internal defects of metal materials. During the detection process, the electromagnetic ultrasonic sensor can generate mechanical vibrations on the surface of the material by changing the magnetic field or current, and form ultrasonic waves. When the ultrasonic waves propagate and reflect in the material, the material will have a slight displacement, thereby changing the magnetic flux distribution of the material, and further affecting the magnetic field of the coil 3 in the sensor. The sensor can convert the influence received into a signal and process it, so as to obtain the defect situation on the surface or inside of the material.

[0038] In this embodiment, the electromagnetic ultrasonic sensor includes a housing and a sensor assembly 1 .

[0039] Among them, the lower end of the shell is used to form a detection end. The shell of the sensor is roughly cylindrical, and its height is small and the overall volume is small. During detection, the lower end of the shell forms the detection end, that is, the lower end of the shell is close to the material to be detected and detects the defects of the material. The material of the shell can be metal material or engineering plastic. The shell of metal material has a good electromagnetic shielding effect, and the engineering plastic has good mechanical properties and chemical stability. It can be selected according to actual needs. Figure 1 and Figure 2 The specific structure of the shell is not shown in the figure, and it can be adaptively configured according to the shape of the sensor component 1, which will not be described in detail here.

[0040] Reference Figure 1 and Figure 2 ,in Figure 1 The structure of the longitudinal section of the sensor assembly 1 is shown. Figure 2 The top view of the sensor assembly 1 is shown. The sensor assembly 1 is installed in a housing and includes a magnet 2 and a coil 3. The magnet 2 includes a cylindrical magnetic core 4 and a ring-shaped magnetic ring 5 surrounding the magnetic core 4. The coil 3 is a concentrically wound circle and is laid flat under the magnet 2.

[0041] Specifically, the magnet 2 is roughly cylindrical and has a small height, so that the overall volume is small. The axis of the magnet 2 coincides with the axial direction of the shell, and the inner diameter of the shell roughly matches the outer diameter of the magnet 2, so that the magnet 2 can be better installed inside the shell. During installation, the bottom wall of the internal cavity of the shell can be fitted with the coil 3 located below the magnet 2, and then a cover plate can be installed on the top of the shell, so that the sensor component 1 is installed and fixed inside the shell.

[0042] Reference Figure 1 and Figure 2 , define a plane where the axis of the magnetic core 4 is located as a first plane 6, and the first plane 6 divides the magnet 2 into a left part 7 and a right part 8; in the left part 7 of the magnetic core 4, the upper half is an N pole and the lower half is an S pole, and in the right part 8, the upper half is an S pole and the lower half is an N pole; in the left part 7 of the magnetic ring 5, the half located on the inner side is an S pole and the half located on the outer side is an N pole, and in the right part 8, the half located on the inner side is an N pole and the half located on the outer side is an S pole.

[0043] Among them, because the magnetic core 4 and the magnetic ring 5 are both rotating structures, the first plane 6 can be any plane where the axis of the magnetic core 4 is located. In this embodiment, for the convenience of explanation, the magnet 2 is divided into a left part 7 and a right part 8 by a first plane 6, but the left part 7 and the right part 8 in the specification and the claims do not mean that the magnet 2 has a left side and a right side. In this embodiment, the magnetic core 4 and the magnetic ring 5 are both magnetized with neodymium magnets, and the magnetic poles in the magnetic core 4 and the magnetic ring 5 can be accurately configured by magnetization. It should be noted that the above-mentioned "upper half", "lower half", "half located on the inner side" and "half located on the outer side" all refer to the half parts that are structurally divided into the corresponding parts of the magnetic core 4 and the magnetic ring 5.

[0044] Due to the polarity configuration of the magnetic core 4 and the magnetic ring 5, the entire magnet 2 forms a composite magnetic field structure. The magnetic core 4 can generate a longitudinal magnetic field, and the magnetic ring 5 can generate an annular magnetic field surrounding the magnetic core 4. The combination of the two makes the magnetic field in the working area of ​​the sensor more concentrated and uniform, so that the sensor can ensure that the magnetic field still has a high intensity while reducing the volume; at the same time, the coil 3 is in a concentrically wound circle and is arranged under the magnet 2. This arrangement can match the magnetic field distribution of the coil 3 with that of the magnet 2, maximize the use of the magnetic field generated by the magnet 2, and the coil 3 here also plays the role of self-excitation and self-reception, which can excite the detected material to vibrate and form ultrasonic waves, and can receive ultrasonic waves waves and form an induction signal; since the coil 3 is arranged below the magnet 2 and overlaps with the concentrated area of ​​the magnetic field, the coupling loss between the coil 3 and the magnetic field is reduced, and since the magnetic field is confined to a smaller area, the coil 3 does not need to be designed to be too large to achieve a sufficient induction effect, thereby reducing the space occupied by the coil 3 and reducing the overall volume of the sensor; in general, the sensor improves the sensor component 1, and these improvements include the structural design of the magnet 2, the configuration of the polarity on the magnet 2, and the positional relationship between the coil 3 and the magnet 2, so that the sensor still has sufficient magnetic field strength and detection sensitivity when the volume is reduced, and detection operations can still be performed in a small space.

[0045] Reference Figure 1 The outer diameter of the coil 3 is consistent with the outer diameter of the magnetic core 4, and it is centered below the magnetic core 4, so that the coil 3 is always in the area with the most concentrated magnetic field, further enhancing the electromagnetic coupling efficiency between the coil 3 and the magnet 2, reducing the magnetic field leakage and invalid sensing area, and reducing the unevenness of the magnetic field distribution, improving the stability of the signal, so that the sensor can achieve better performance in a smaller size.

[0046] Preferably, two layers of coils 3 are stacked and connected in series below the magnet 2. Specifically, when the two layers of coils 3 are coiled, a single conductive wire can be first coiled from the inside to the outside in a concentric manner to form a circle as the first layer, and then the outermost coil 3 of the first layer is bent downward at an angle and coiled from the outside to the inside to form a circle as the second layer, and then the final end of the conductive wire is led out to the outside of the coil 3. At this time, the beginning and end of the coil 3 are both located outside the coil 3, so as to facilitate connection with the signal generator and signal processor in the electromagnetic ultrasonic detection equipment. In addition, by laying a double layer of coils 3, the sensitivity of electromagnetic induction can be enhanced while the volume is reduced, and because the two coils 3 are connected in series and are both under the magnetic core 4, the magnetic fields can be superimposed on each other, thereby further enhancing the magnetic field strength of the sensor.

[0047] Reference Figure 1 , the lower end of the magnetic ring 5 is flush with the lower end of the magnetic core 4, and the upper end thereof is higher than the upper end of the magnetic core 4. Preferably, the height difference between the upper end of the magnetic ring 5 and the upper end of the magnetic core 4 can be 20% of the length of the magnetic core 4. By making the upper end of the magnetic ring 5 higher than the upper end of the magnetic core 4, the lift-off signal can be suppressed during the detection process, and the sound waves generated by the vibration of the material can be stabilized and centered during the detection process, thereby improving the detection accuracy.

[0048] Reference Figure 1 and Figure 2 The magnet 2 further includes a copper foil 9 disposed between the magnetic core 4 and the magnetic ring 5, and the inner and outer sides of the copper foil 9 are respectively attached to the outer wall of the magnetic core 4 and the inner wall of the magnetic ring 5. The purity of the copper foil 9 is higher than 99%, thereby isolating the interference of the useless magnetic field on the coil 3 and further improving the detection effect.

[0049] Preferably, the thickness of the copper foil 9 is 8% of the outer diameter of the magnetic core 4. Under this size limitation, the copper foil 9 can be adapted to the size of the magnetic core 4, and the useless magnetic field can be better isolated.

[0050] In addition, the difference between the outer diameter and the inner diameter of the magnetic ring 5 is 22% of the outer diameter of the magnetic core 4, the length of the magnetic ring 5 is 120% of the length of the magnetic core 4, and the outer diameter of the magnetic core 4 is not less than 10 mm. Specifically in this embodiment, since the purpose of the present invention is to provide a small-sized electromagnetic ultrasonic sensor, the outer diameter of the magnetic core 4 is set to 10 mm, at which time the outer diameter of the magnetic ring 5 is 16 mm, the inner diameter of the magnetic ring 5 is 11.6 mm, the width of the magnetic ring 5 is 4.4 mm, and the thickness of the copper foil 9 is 8 mm. At the same time, the height of the magnetic core 4 is set to 5 mm, the height of the magnetic ring 5 is 6 mm, and the height difference between the upper ends of the two is 1 mm.

[0051] By limiting the difference between the outer diameter and the inner diameter of the magnetic ring 5, and limiting the length of the magnetic ring 5 and the length of the magnetic core 4, under this size limitation, the matching effect between the magnetic core 4 and the magnetic ring 5 of the magnet 2 is better, and a high-intensity magnetic field can be provided in a smaller volume, thereby ensuring the detection effect.

[0052] At the same time, refer to Figure 1 A buffer layer 10 is provided between the wire weight and the magnetic core 4. The buffer layer 10 is an iron-nickel-cobalt alloy, wherein the nickel content is 49%-51%, the iron content is 32%-33%, and the cobalt content is 16%-17%. The buffer layer 10 with a specific metal component content can improve the stability of the sensor excitation and induction signals and make the magnetic field distribution more uniform.

[0053] Example 2

[0054] Embodiment 2 of the present invention provides an electromagnetic ultrasonic detection device, which includes a signal generator, a signal processor, and the electromagnetic ultrasonic sensor provided in embodiment 1, wherein the electromagnetic ultrasonic sensor is electrically connected to the signal generator and the signal processor. The detection device uses the electromagnetic ultrasonic sensor and can perform detection operations in a small space.

[0055] The description of the above specification and embodiments is used to explain the protection scope of the present invention, but does not constitute a limitation on the protection scope of the present invention. Through the enlightenment of the present invention or the above embodiments, ordinary technicians in this field can obtain modifications, equivalent substitutions or other improvements to the embodiments of the present invention or part of the technical features thereof through logical analysis, reasoning or limited experiments, which should be included in the protection scope of the present invention.

Claims

1. An electromagnetic ultrasonic sensor, characterized in that: include: A housing, the lower end of which is used to form a detection end; A sensor assembly (1) is installed in the housing and comprises a magnet (2) and a coil (3); the magnet (2) comprises a cylindrical magnetic core (4) and a ring-shaped magnetic ring (5) surrounding the magnetic core (4); the coil (3) is in the shape of a concentrically wound circle and is laid flat below the magnet (2); A plane in which the axis of the magnetic core (4) is located is defined as a first plane (6), and the first plane (6) divides the magnet (2) into a left part (7) and a right part (8); in the left part (7) of the magnetic core (4), the upper half is an N pole and the lower half is an S pole, and in the right part (8), the upper half is an S pole and the lower half is an N pole; in the left part (7) of the magnetic ring (5), the half located on the inner side is an S pole and the half located on the outer side is an N pole, and in the right part (8), the half located on the inner side is an N pole and the half located on the outer side is an S pole.

2. An electromagnetic ultrasonic sensor as claimed in claim 1, characterized in that: The outer diameter of the coil (3) is consistent with the outer diameter of the magnetic core (4), and the coil (3) is centrally located below the magnetic core (4).

3. An electromagnetic ultrasonic sensor as claimed in claim 2, characterized in that: Two layers of coils (3) connected in series are stacked and laid below the magnet (2).

4. An electromagnetic ultrasonic sensor as claimed in claim 2, characterized in that: The lower end of the magnetic ring (5) is flush with the lower end of the magnetic core (4), and the upper end of the magnetic ring (5) is higher than the upper end of the magnetic core (4).

5. An electromagnetic ultrasonic sensor as claimed in claim 4, characterized in that: The height difference between the upper end of the magnetic ring (5) and the upper end of the magnetic core (4) is 20% of the length of the magnetic core (4).

6. An electromagnetic ultrasonic sensor as claimed in claim 5, characterized in that: The magnet (2) further comprises a copper foil (9) arranged between the magnetic core (4) and the magnetic ring (5), wherein the inner and outer sides of the copper foil (9) are respectively attached to the outer wall of the magnetic core (4) and the inner wall of the magnetic ring (5).

7. An electromagnetic ultrasonic sensor as claimed in claim 6, characterized in that: The thickness of the copper foil (9) is 8% of the outer diameter of the magnetic core (4).

8. An electromagnetic ultrasonic sensor according to any one of claims 1 to 7, characterized in that: The difference between the outer diameter and the inner diameter of the magnetic ring (5) is 22% of the outer diameter of the magnetic core (4); the length of the magnetic ring (5) is 120% of the length of the magnetic core (4); and the outer diameter of the magnetic core (4) is not less than 10 mm.

9. An electromagnetic ultrasonic sensor as claimed in claim 6, characterized in that: A buffer layer (10) is provided between the coil (3) and the magnetic core (4), and the buffer layer (10) is an iron-nickel-cobalt alloy, wherein the nickel content is 49%-51%, the iron content is 32%-33%, and the cobalt content is 16%-17%.

10. An electromagnetic ultrasonic testing device, comprising a signal generator and a signal processor, characterized in that: It also includes an electromagnetic ultrasonic sensor as described in any one of claims 1 to 9, wherein the electromagnetic ultrasonic sensor is electrically connected to the signal generator and the signal processor.

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