Constant-temperature focusing type pulsed eddy current sensor

Abstract

The utility model relates to a constant-temperature focusing type pulsed eddy current sensor which comprises a base, a liquid inlet pipe and a liquid outlet pipe which are arranged on the left side and the right side of the sensor, an exciting coil arranged above the base, a magnetic tank arranged above the exciting coil, a magnetic tank support arranged between the exciting coil and the magnetic tank, and a pressing block arranged above the magnetic tank. A receiving coil is arranged between the magnetic tank and the inner wall of the base, the parts are arranged in a shell, a protective layer is arranged between the shell and the base, an end cover is arranged above the shell, and a rubber gasket is arranged between the shell and the end cover and is tightly connected with the shell; according to the utility model, not only can a primary magnetic field and a secondary magnetic field be focused, but also the working temperature is constant, so as to meet the detection requirements of higher spatial resolution, signal-to-noise ratio and result degree.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of nondestructive testing, in particular to a constant temperature focusing type pulse eddy current sensor. BACKGROUND

[0002] The pulse eddy current sensor is generally composed of an excitation coil and a receiving coil. When the sensor is working, a rectangular wave voltage is loaded on both ends of the excitation coil. In the high level section of the rectangular wave voltage, the excitation coil generates a primary magnetic field acting on the measured conductor. When the rectangular wave voltage jumps from high level to low level, the primary magnetic field sharply decreases, and an induced eddy current is generated in the measured conductor. At the same time, the induced eddy current generates a secondary magnetic field, and the induced eddy current dissipates in the measured conductor. The dissipation process is related to the electromagnetic parameters and structural size of the measured conductor. By analyzing the voltage signal (pulse eddy current detection signal) obtained by converting the change rate of the secondary magnetic field by the receiving coil, the electromagnetic parameters and structural size of the measured conductor can be detected.

[0003] In the high level section of the rectangular wave voltage, the excitation coil generates heat while generating the primary magnetic field, which leads to an increase in the temperature of the excitation coil, and further increases the resistance of the excitation coil and the receiving coil wound by enameled metal wire, reduces the current in the excitation coil, and reduces the primary magnetic field. The pulse eddy current detection signal will change accordingly, which affects the detection result. In addition, the resistance of the existing excitation coil and receiving coil is easily affected by the change of the environmental temperature, which is difficult to meet the high-precision detection requirement.

[0004] Currently, the development of the pulse eddy current detection technology is limited due to the influence of temperature on the probe. In view of this, Chinese invention patent ZL201510220868.7 obtains the temperature of the pulse eddy current probe by arranging a temperature sensing component in the pulse eddy current probe, compensates the signal characteristics for temperature, and improves the precision of the metal surface defect depth detection. However, this method needs to know the relationship between the signal characteristics and the probe temperature in advance, and is often only applicable to single variable detection. In the actual detection process, the signal characteristics are often affected by multiple variables, such as the change of lift-off (the distance between the probe and the measured conductor). In addition, this method cannot avoid the damage of the probe due to excessive heat generated by the excitation coil during the detection process. Chinese invention patent ZL202311495195.7 uniformly conducts the heat generated by the excitation coil in the pulse eddy current detection process to the probe metal shell through the insulating heat-conducting silica gel, avoids the damage of the coil due to overheating of the probe, and significantly improves the continuous scanning time of the pulse eddy current. However, in the scheme of the invention patent, the heat conduction will be affected by the environment temperature of the probe, and the outside of the excitation coil will be cooled quickly due to the contact with the insulating heat-conducting silica gel, while the upper side, lower side and inner side of the excitation coil will be cooled slowly due to the distance from the insulating heat-conducting silica gel. The receiving coil located on the inner side of the excitation coil may be affected by the temperature rise on the inner side of the excitation coil, and then the signal will be affected. In addition, in the scheme of the invention patent, due to the lack of temperature sensors, the internal temperature of the eddy current probe cannot be accurately known, which is not conducive to keeping the internal temperature of the eddy current probe constant, and is not conducive to temperature compensation. Chinese invention patent ZL202110582341.4 uses heat-conducting silica gel to paste 2 semi-circular ring-shaped heat sinks outside the excitation coil for heat dissipation, but in the scheme of the invention patent, the temperature of the excitation coil will be affected by the environment temperature. Chinese utility model patent ZL202220098488.6 uses a framework filled with heat-conducting silica gel with heat dissipation holes to dissipate heat from the excitation coil, but in the scheme of the utility model patent, the temperature of the excitation coil will also be affected by the environment temperature.

[0005] Pulsed eddy current testing technology is a branch of eddy current testing technology. The probe of the eddy current testing technology is also susceptible to temperature. Therefore, the Chinese utility model patent ZL93244850.X uses air cooling and water cooling to keep the temperature inside the eddy current probe below 40℃. However, in the scheme of the utility model patent, the temperature inside the eddy current probe cannot be accurately known due to the lack of temperature sensors, which is not conducive to keeping the temperature inside the eddy current probe constant and not conducive to temperature compensation. The Chinese invention patent ZL201911390265.6 places the eddy current probe in a constant temperature cavity, and through a heating cavity outside the constant temperature cavity, the eddy current probe is kept in a constant temperature state as much as possible when detecting in different boric acid water temperature intervals. However, in the scheme of the utility model patent, the eddy current probe can only be warmed up, but cannot be cooled down, and due to the lack of convection in the constant temperature cavity, there may be problems such as slow temperature rise of the eddy current probe and uneven temperature distribution. The Chinese utility model patent ZL201921150635.4 arranges a circulating liquid flow channel on the side and bottom of the eddy current testing assembly, and arranges a temperature sensor on the inner wall of the chamber where the eddy current testing assembly is located, to avoid the influence of high temperature environment on the detection accuracy of the eddy current testing assembly. However, in the scheme of the utility model patent, due to the lack of convection in the chamber where the eddy current testing assembly is located, and the temperature sensor does not directly obtain the temperature of the eddy current testing assembly, there may be problems such as uneven temperature distribution and slow temperature control response of the eddy current testing assembly. The Chinese utility model patent ZL202322332248.5 arranges a heat dissipation shell outside the excitation coil, and uses microwave heating to fill pure water inside the excitation coil, so as to maintain a constant temperature inside the eddy current sensor. However, in the scheme of the utility model patent, the temperature inside the eddy current sensor will be affected by the ambient temperature of the eddy current sensor, and cannot be lower than the ambient temperature. In addition, in the scheme of the utility model patent, due to the lack of temperature sensors, the temperature inside the eddy current probe cannot be accurately known, which is not conducive to keeping the temperature inside the eddy current probe constant and not conducive to temperature compensation.

[0006] In addition, in the existing scheme, whether temperature compensation is performed after temperature measurement or the excitation coil is cooled, it is difficult to apply to the focusing of primary magnetic field and secondary magnetic field. The focusing of primary magnetic field and secondary magnetic field is often realized by placing the excitation coil in a magnetic tank or other magnetic structure member, so as to improve the spatial resolution and signal signal-to-noise ratio of detection. However, since the excitation coil is closely placed in the magnetic tank or other magnetic structure member, there is a lack of convection, and the excitation coil is difficult to cool down. On the one hand, the resistance of the excitation coil increases due to the temperature rise, and the primary magnetic field decreases with the decrease of the current in the excitation coil. On the other hand, the magnetic permeability of the magnetic tank or other magnetic structure member decreases due to the temperature rise, and the focusing ability of the primary magnetic field and the secondary magnetic field decreases, thereby reducing the spatial resolution and signal signal-to-noise ratio of detection. Utility model content

[0007] In order to overcome the above prior art, the utility model discloses a constant temperature focusing pulse eddy current sensor device, which can realize the focusing of primary magnetic field and secondary magnetic field, and realize the constant temperature of the sensor inside, so as to meet the detection demand of high spatial resolution, signal signal noise ratio and result accuracy.

[0008] In order to realize the above-mentioned purpose, the utility model adopts the technical scheme of:

[0009] A constant temperature focusing pulse eddy current sensor, including base, the liquid inlet pipe is installed to the right side of base, the liquid outlet pipe is installed to the left side of base, and the base is equipped with the excitation coil, the magnetic tank is equipped above the excitation coil, the magnetic tank support is equipped between the excitation coil, the pressing block is installed above the magnetic tank, and the receiving coil is equipped between the magnetic tank and the inner wall of base, these components are installed in the shell, the end cover is equipped above the shell, the rubber gasket is equipped between the end cover and the shell and is closely connected, and the 6 core waterproof joint is equipped directly above the end cover.

[0010] The lower inner cavity (115) of the bottom of the base is a liquid inlet channel, and the lower outer cavity (116) is a liquid outlet channel.

[0011] The magnetic tank support is "door" shaped, and a plurality of magnetic tank supports are evenly distributed and clamped on the upper side, the inner side and the outer side of the excitation coil, so as to prevent the excitation coil and the magnetic tank from shaking, and the gap generated between the excitation coil and the magnetic tank enables the constant temperature liquid to flow around the excitation coil.

[0012] The 6 core waterproof joint is connected with the excitation coil, the receiving coil and the temperature sensor.

[0013] The rubber gasket is arranged between the end cover and the shell, and is connected through bolts, so as to play a sealing role.

[0014] The protective layer is arranged between the shell and the base.

[0015] The shell is made of ABS material and is filled with a honeycomb type inside, and the protective layer is made of B1 grade flame-retardant polystyrene foam material.

[0016] The utility model has the advantages of:

[0017] 1. The utility model discloses a specific base, and the constant temperature liquid passes through the designed channel to the excitation coil, the receiving coil and the magnetic tank of the sensor, so as to improve the detection precision.

[0018] 2. The utility model discloses a magnetic tank, which can focus the primary magnetic field and the secondary magnetic field, so as to improve the spatial resolution and the signal noise ratio of the pulse eddy current detection.

[0019] 3. The shell is made of ABS material, and the inside is filled with honeycomb type, the protective layer is made of B1 grade flame-retardant polystyrene foam material, which will not affect the pulse eddy current detection signal, has good shock resistance and flame resistance effect, and is durable.

[0020] 4. The utility model discloses clever structure design can be made through 3D printing technology. DRAWINGS

[0021] Figure 1 It is the three-dimensional drawing of the utility model patent after assembly.

[0022] Figure 2 It is the utility model patent's explosion map.

[0023] Figure 3 It is the utility model patent's sectional view.

[0024] Figure 4 It is the structure schematic diagram of base.

[0025] Figure 5 It is the base internal flow passage schematic diagram.

[0026] In the drawing: 1, liquid inlet pipe; 2, rubber gasket; 3, briquetting; 4, magnetic tank; 5, temperature sensor; 6, excitation coil; 7, magnetic tank support; 8, receiving coil; 9, shell; 10, protective layer; 11, base; 12, end cover; 13, liquid outlet pipe; 14, 6-core waterproof joint. SPECIFIC EMBODIMENTS

[0027] In order to make the technical problems, technical schemes and beneficial effects solved by the application more clear and definite, the technical schemes in the utility model will be described clearly and completely in conjunction with the drawings. Obviously, the described embodiments are only part of the embodiments of the utility model patent, not all the embodiments. It should be understood that the specific embodiments described herein are only used to explain the application, and are not used to limit the application.

[0028] The utility model patent relates to the field of nondestructive testing, and particularly relates to a constant-temperature focusing type pulse eddy current sensor. The sensor can focus on the primary magnetic field and the secondary magnetic field, and the working temperature is constant, so that the detection requirements of high spatial resolution, signal signal-to-noise ratio and result accuracy are met.

[0029] As Figure 1 , 2, 4, a constant temperature focusing type pulse eddy current sensor, comprising a base 11, the right side of the base 11 is provided with a liquid inlet pipe 1, the left side of the base 11 is provided with a liquid outlet pipe 13, the upper side of the base 11 is provided with an excitation coil 6, the upper side of the excitation coil 6 is provided with a magnetic tank 4, the magnetic tank 4 and the excitation coil 6 are provided with a magnetic tank support 7, the upper side of the magnetic tank 4 is provided with a pressing block 3, the magnetic tank 4 and the inner wall of the base 11 are provided with a receiving coil 8, these components are installed in a shell 9, the upper side of the shell 9 is provided with an end cover 12, the end cover 12 and the shell 9 are provided with a rubber gasket 2 and are tightly connected, the upper side of the end cover 12 is provided with a 6-core waterproof joint 14.

[0030] As shown in Figure 4 , the right side of the base 11 is designed with a liquid inlet connection joint 113, the left side is designed with a liquid outlet connection joint 114, the base liquid inlet 112 and the base liquid outlet 111.

[0031] The internal flow channel of the base 11 is shown in Figure 5 , the lower inner cavity (115) is connected with the liquid inlet connection joint 113, the lower outer cavity (116) is connected with the liquid outlet connection joint 114, the base liquid inlet 112 and the lower inner cavity (115) are in the same vertical direction, the base liquid outlet 111 and the lower outer cavity (116) are in the same vertical direction, a partition is designed between the lower inner cavity (115) and the lower outer cavity (116), and the two are not communicated.

[0032] As shown in Figure 3 , the magnetic tank 4 and the excitation coil 6 are provided with 7 "door" shaped magnetic tank supports 7, which are used to fix the positions of the excitation coil 6 and the magnetic tank 4 and avoid shaking, and are also used to generate a gap between the excitation coil 6 and the magnetic tank 4, so that the constant temperature liquid can flow around the excitation coil 6 to stabilize the temperature of the excitation coil 6.

[0033] The 6-core waterproof joint 14 is connected with the excitation coil 6, the receiving coil 8 and the temperature sensor. The temperature sensor is used to monitor the internal temperature of the sensor. The temperature sensor is arranged close to the inner side of the excitation coil 6 and is used to monitor the temperature of the excitation coil 6.

[0034] As shown in Figure 3 , the liquid inlet pipe 1, the pressing block 3, the base 11, the excitation coil 6, the magnetic tank 4, the magnetic tank support 7, the receiving coil 8, the protective layer 10 and the liquid outlet pipe 13 are all installed in the shell 9, each part is tightly matched, the movable range is small, and the shaking is small.

[0035] As shown in Figure 3As shown, the shell 9 and the base 11 are provided with a protective layer 10. The shell 9 is printed by an FDM printer, and the material is ABS material. The shell 9 is filled with a honeycomb type, which has the advantages of light weight, shock resistance, and good wear resistance. The protective layer 10 is made of B1 grade flame-retardant polystyrene foam material, which has good flame-retardant effect and can also serve as a base. The base is printed by a light curing printer, and the surface and internal flow channel are smooth.

[0036] The working principle of the utility model is as follows:

[0037] First, the constant temperature liquid filled in the sensor is heated to a specified temperature by an external constant temperature device. Then, when detecting, the constant temperature liquid at the specified temperature is injected into the liquid inlet pipe 1. The constant temperature liquid flows through the excitation coil 6 from the lower side and the inner side to the outer side in two ways, reaches the base liquid outlet 111, and flows out of the sensor through the lower outer cavity (116) and the liquid outlet pipe 13, thereby reducing the temperature fluctuation of the excitation coil 6, the receiving coil 8, and the magnetic tank 6 in the sensor, improving the repeatability of the primary magnetic field, the repeatability of the pulse eddy current detection signal converted from the secondary magnetic field change rate, and the stability of focusing the primary magnetic field and the secondary magnetic field, thereby improving the detection accuracy. The constant temperature method is conducive to focusing the primary magnetic field and the secondary magnetic field by the magnetic tank and other magnetic guiding structural members, thereby improving the spatial resolution of the pulse eddy current detection and the signal-to-noise ratio of the signal.

[0038] The utility model patent is not limited to the above examples. Changes, modifications, additions, or replacements made by ordinary personnel in the technical field within the substantial scope of the utility model patent also belong to the protection scope of the utility model patent.

Claims

1. A constant temperature focused pulsed eddy current sensor, comprising a base (11), characterized in that: A liquid inlet pipe (1) is installed on the right side of the base (11), and a liquid outlet pipe (13) is installed on the left side of the base (11). An excitation coil (6) is provided above the base (11), a magnetic tank (4) is provided above the excitation coil (6), a magnetic tank bracket (7) and a temperature sensor (5) are provided between the magnetic tank (4) and the excitation coil (6), a pressing block (3) is installed above the magnetic tank (4), and a receiving coil (8) is provided between the magnetic tank (4) and the inner wall of the base (11). These components are installed in a shell (9), an end cover (12) is provided above the shell (9), a rubber gasket (2) is provided between the end cover (12) and the shell (9) and is tightly connected, and a 6-core waterproof connector (14) is provided directly above the end cover (12).

2. The constant temperature focused pulsed eddy current sensor according to claim 1, characterized in that: The lower inner cavity (115) at the bottom of the base (11) is a liquid inlet channel, and the lower outer cavity (116) is a liquid outlet channel.

3. The constant temperature focused pulsed eddy current sensor according to claim 1, characterized in that: The magnetic tank bracket (7) is in a "door" shape, and a plurality of magnetic tank brackets are evenly distributed and clamped on the upper side, inner side and outer side of the excitation coil to prevent the excitation coil and the magnetic tank from shaking. The gap thus generated between the excitation coil and the magnetic tank allows the constant temperature liquid to flow around the excitation coil.

4. The constant temperature focused pulsed eddy current sensor according to claim 1, characterized in that: The 6-core waterproof connector (14) is connected to the excitation coil (6), the receiving coil (8) and the temperature sensor.

5. The constant temperature focused pulsed eddy current sensor according to claim 1, characterized in that: A rubber gasket (2) is provided between the end cover (12) and the housing (9), and the two are connected by bolts to provide a seal.

6. The constant temperature focused pulsed eddy current sensor according to claim 1, characterized in that: A protective layer (10) is provided between the housing (9) and the base (11).

7. The constant temperature focused pulsed eddy current sensor according to claim 6, characterized in that: The outer shell (9) is made of ABS material, and the interior is filled with a honeycomb type, and the protective layer (10) is made of B1 grade flame retardant polystyrene foam material.

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