Ferromagnetic interference resistant nondestructive testing device for foundation bolt of power transmission tower

Abstract

An anti-ferromagnetic-interference nondestructive testing device for foundation bolts of a power transmission tower comprises a magnetic field generation module, a coil module is arranged in the magnetic field generation module, a multi-diameter variable-turn coil is arranged in the coil module, a signal receiving module is arranged at the center of the coil module, and the coil module is electrically connected with the output end of a signal processing module. The signal receiving module is electrically connected with the input end of the signal processing module. In order to better adapt to the complex ferromagnetic detection environment that stiffening plates, rib plates, rigid gaskets and the like are arranged on the periphery of the foundation bolt of the power transmission tower and to better adapt to the detection of the specifications of the foundation bolts of the power transmission towers with different diameters. According to the device, power transmission tower foundation bolt detection environments are reasonably divided into three classes I, II and III according to the interference degree of the bolts, and multi-diameter and multi-turn design is creatively carried out on the excitation coil for emitting a magnetic field, so that the device can generate a more suitable detection magnetic field; and meanwhile, the power transmission tower foundation bolt detection threshold is established, and detection results are classified, so that the detection results are more accurate.

Description

Technical Field

[0001] The utility model relates to the technical field of nondestructive testing, in particular to a nondestructive testing device for the anchor bolts of transmission towers that resists ferromagnetic interference. Background Technique

[0002] As a key link in power transmission, ensuring the safe operation of transmission towers is the focus of ensuring energy supply. Among them, the anchor bolts used to fixedly connect the foundation of the transmission tower and the tower legs may have the defect of missing nuts due to various uncertain factors such as construction workers during the construction process. This defect makes the connection between the tower and the foundation insecure, directly affecting the bearing capacity of the transmission tower and leaving potential hidden dangers for the safe operation of the transmission tower. Eliminating such hidden dangers is of great significance for ensuring the safe operation of the entire overhead transmission line.

[0003] The anchor bolts of transmission towers include screw rods and nuts. Considering that the presence or absence of nuts is manifested as a change in the diameter of the steel, the current solutions to similar problems mainly focus on electromagnetic nondestructive testing techniques for detecting indicators such as the diameter of steel bars in reinforced concrete structures. Chen Xingle et al. (CN115479530A) proposed a method for detecting and analyzing the diameter of the inspected steel bars buried in concrete by using the characteristic quantities of the pulsed eddy current signals received by the coil in electromagnetic induction. By comparing the detected values with the signals generated by steel bars of standard diameter, the influence of the electromagnetic parameters of the steel bars on the test results can be well eliminated, and the diameter of the steel bars buried in the concrete can be obtained. However, in this solution, the detection coil is single, and the magnetic field distribution cannot change well according to the environment, resulting in fewer target object diameters that can be detected by this device. At the same time, this solution cannot well detect the diameter of the steel bars in the face of complex ferromagnetism. Jin Shan et al. (CN113566692A) invented a nondestructive testing device for the quality of cable cement protection covers. This device forms a scanning signal envelope diagram by obtaining the scanning signal waveform diagrams of a sufficient number of standard components, and determines whether the position and diameter of the steel bars in the cover are qualified by comparing the actual measurement results. This method can well improve the detection efficiency of the cover when detecting concrete covers with sparse steel bar spacing and little ferromagnetic environment interference. Similarly, in this method, the coil diameter is fixed, and it will be very difficult to achieve the desired detection effect in the case of dense steel bars and more ferromagnetic environment interference. Wang Junchao et al. (CN114812477A) proposed a method for detecting the spacing between steel bars in a concrete structure. This solution improves the detection accuracy by scanning the spacing between multiple steel bars and taking the average value through the principle of electromagnetic induction. However, in the face of non-uniformly arranged detection objects, this solution cannot be well solved. Summary of the Invention

[0004] The technical problem to be solved by the present utility model is to provide a non-destructive testing device for the anchor bolts of a transmission tower that resists ferromagnetic interference. The exciting coil that emits a magnetic field is designed with multiple diameters and multiple turns. This design enables the device to generate a more suitable detection magnetic field. At the same time, a detection threshold for the anchor bolts of the transmission tower is established to classify the detection results, making the detection results more accurate.

[0005] To solve the above technical problems, the technical solution adopted by the present utility model is:

[0006] A non-destructive testing device for the anchor bolts of a transmission tower that resists ferromagnetic interference, including a magnetic field generation module for generating a magnetic field. A coil module is provided inside the magnetic field generation module. A multi-diameter variable-turn coil is provided inside the coil module. A signal receiving module is provided at the center of the coil module. The coil module is electrically connected to the output end of the signal processing module, and the signal receiving module is electrically connected to the input end of the signal processing module. Different ranges and intensities of magnetic field signals are generated by the coils with different diameters and turns inside the coil module to act on the materials in the detection area. Then, the magnetic field feedback signal of the target bolt in the detection area received by the detection signal receiving module is used to judge the condition of the bolt.

[0007] The above-mentioned signal processing module is communicatively connected to the display module.

[0008] The above-mentioned signal processing module is electrically connected to the human-computer interaction module.

[0009] The above-mentioned multi-diameter variable-turn coil includes multiple groups of coaxial coils with different diameters.

[0010] Each single-diameter coil in the above-mentioned multiple groups of coaxial coils with different diameters includes multiple coils with different numbers of turns.

[0011] The above-mentioned multi-diameter variable-turn coil includes three groups of coils with diameters of R1, R2, and R3, where R1 < R2 < R3.

[0012] In the above-mentioned three groups of coils with diameters of R1, R2, and R3, each group of coils respectively includes four coils with numbers of turns of Na, Nb, Nc, and Nd.

[0013] In the above-mentioned three groups of coils with diameters of R1, R2, and R3, the four coils in each group of coils include a common positive terminal and four negative terminals with different numbers of turns. The positive terminals of the R1, R2, and R3 coils are the first positive terminal, the second positive terminal, and the third positive terminal respectively. The negative terminals with different numbers of turns in each group of coils are the Na negative terminal, the Nb negative terminal, the Nc negative terminal, and the Nd negative terminal.

[0014] The above-mentioned magnetic field generation module, signal receiving module, signal processing module, display module, and human-computer interaction module are electrically connected to the power supply module.

[0015] The non-destructive testing device for the anchor bolts of a transmission tower that resists ferromagnetic interference provided by the present utility model has the following beneficial effects:

[0016] 1. The device of the present invention realizes electromagnetic non-destructive testing on whether there is a defect of missing nuts in the screw rods of the anchor bolts of a transmission tower in a complex ferromagnetic environment without damaging the concrete protective cap.

[0017] 2. According to the degree of interference suffered by the anchor bolts, the detection environment is divided into three categories: I, II, and III. For these three types of detection environments, the detection coils in the coil module of the device are designed with 3 diameters, so that when the device faces different detection environments, the magnetic field generated by the magnetic field generation module can be concentrated near the target bolt, reducing the electromagnetic interference brought by the environment to the screw rod.

[0018] 3. According to the different magnetic field intensities required for detecting anchor bolts of different diameters, in the coil module, the number of coil turns matching the diameter is provided, so that the magnetic field intensity generated by the detection device can reach the requirements of detection.

[0019] 4. The device of the present invention sets a detection standard library for anchor bolts in the signal processing module to judge the situation of missing nuts of the anchor bolts of a transmission tower; a method combining preset thresholds and correcting thresholds according to actual detection results is adopted to improve the determination accuracy of the detection threshold and the environmental adaptability of the device. At the same time, according to the detected magnetic field intensity, 4 kinds of detection results are given, which can more accurately express the situation of missing nuts of the anchor bolts. Description of the Drawings

[0020] The following further describes the present utility model in conjunction with the drawings and embodiments:

[0021] Figure 1 is the schematic diagram of the external structure of the device of the present utility model;

[0022] Figure 2 is the position diagram of each module inside the device;

[0023] Figure 3 is the sectional view of the multi-diameter variable-turn coil module;

[0024] Figure 4 is the schematic diagram of three types of detection environments for anchor bolts.

[0025] In the figure: Negative terminal 1 of Na, Negative terminal 2 of Nb, Negative terminal 3 of Nc, Negative terminal 4 of Nd, First positive terminal 5, Second positive terminal 6, Third positive terminal 7, Magnetic field generation module 8, Signal receiving module 9, Signal processing module 10, Display module 11, Human-computer interaction module 12, Power supply module 13, Coil module 14. Detailed implementation mode

[0026] A non-destructive testing device for the anchor bolts of a transmission tower against ferromagnetic interference, including a magnetic field generating module 8 for generating a magnetic field. A coil module 14 is provided inside the magnetic field generating module 8. A multi-diameter variable-turn coil is provided inside the coil module 14. A signal receiving module 9 is provided at the center of the coil module 14. The coil module 14 is electrically connected to the output end of the signal processing module 10, and the signal receiving module 9 is electrically connected to the input end of the signal processing module 10. Different ranges and intensities of magnetic field signals are generated by the coils with different diameters and turns inside the coil module 14 to act on the materials in the detection area. Then, the magnetic field feedback signal of the target bolt in the detection area received by the detection signal receiving module 9 is used to judge the condition of the bolt.

[0027] The above-mentioned signal processing module 10 is communicatively connected to the display module 11.

[0028] The above-mentioned signal processing module 10 is electrically connected to the human-computer interaction module 12.

[0029] The above-mentioned multi-diameter variable-turn coil includes multiple groups of coaxial coils with different diameters.

[0030] Each single-diameter coil in the above-mentioned multiple groups of coaxial coils with different diameters contains multiple coils with different turns.

[0031] The above-mentioned multi-diameter variable-turn coil includes three groups of coils with diameters of R1, R2, and R3, where R1 < R2 < R3.

[0032] In the above-mentioned three groups of coils with diameters of R1, R2, and R3, each group of coils respectively includes four coils with turns of Na, Nb, Nc, and Nd.

[0033] In the above-mentioned three groups of coils with diameters of R1, R2, and R3, the four coils in each group of coils include a common positive terminal and four negative terminals with different turns. The positive terminals of the R1, R2, and R3 coils are the first positive terminal 5, the second positive terminal 6, and the third positive terminal 7 respectively. The negative terminals with different turns in each group of coils are the Na negative terminal 1, the Nb negative terminal 2, the Nc negative terminal 3, and the Nd negative terminal 4.

[0034] The above-mentioned magnetic field generating module 8, signal receiving module 9, signal processing module 10, display module 11, and human-computer interaction module 12 are electrically connected to the power supply module 13.

[0035] Example:

[0036] A non-destructive testing device for the anchor bolts of transmission towers against ferromagnetic interference, characterized in that the device mainly includes a magnetic field generation module 8, a signal reception module 9, a signal processing module 10, a display module 11, a human-computer interaction module 12, and a power supply module 13; as Figure 1 , Figure 2 shown.

[0037] In the coil module 14 of the magnetic field generation module 8, multi-diameter variable-turn coils are designed. The coil module 14 is used for the non-destructive testing of the anchor bolts of transmission towers in various detection environments, so that the magnetic field distribution can be better concentrated near the target screw, and at the same time, the device can obtain electromagnetic signals with sufficient intensity when detecting bolts of different specifications. The coil module 14 is as Figure 3 shown.

[0038] For the four anchor bolt specifications of M24, M30, M36, and M42, in order to ensure that the detection results can reach sufficient accuracy, the device can generate four different intensities of magnetic field signals, and four coil groups with different numbers of turns are correspondingly set, namely Na, Nb, Nc, Nd, where the number of turns is in the order of Na < Nb < Nc < Nd; at the same time, during the detection process, the detection interference brought by the detection environment should be excluded. In the design of the coil module 14, three different diameters of detection coils are used, as Figure 3 shown, that is, the diameters R1, R2, R3 and R1 < R2 < R3; when the module needs to connect the coil circuit with the corresponding diameter and number of turns, by connecting the cathode terminals 1, 2, 3, 4 and the anode terminals 5, 6, 7 corresponding to the environment and bolt model in the module, where the anode terminals can be selected to change the diameter of the coil module, and the cathode terminals can be selected to change the number of turns of the coil module; for example, when the circuit is connected to the cathode terminal 1 and the anode terminal 5 of the module, the module will select a coil with a diameter of R1 and a number of turns of Na to generate a magnetic field for detection. The operator can select the corresponding coil diameter and number of turns according to the specific environment and the diameter of the anchor bolt. When the module is connected, the coil module can generate the corresponding magnetic field intensity distribution.

[0039] As Figure 4 shown, according to the interference degree of ferromagnetic substances on the ferromagnetic signals of the anchor bolts, the detection environment of the anchor bolts of transmission towers is divided into three categories, namely categories I, II, and III detection environments, where the interference degree increases in the order of II, III, I. Therefore, in the face of the interference of different detection environments, the magnetic field distribution is adjusted through the coil module 14. When the electromagnetic interference in the environment is greater, the magnetic field distribution needs to be more concentrated near the target screw, and the selected coil diameter should be smaller. According to Figure 4As can be seen from the reference diagram of the transmission tower screw and the detection environment, there are many ferromagnetic substances in the I environment where the screw ① is located. In addition, the stiffening plates on both sides also make the detection window smaller, and it is very easy to be interfered by the ferromagnetic signals generated by the stiffening plates during detection. Therefore, in order to make the magnetic field highly concentrated near the screw position during detection, a coil with a diameter of R1 is used for detection. By analogy, the detection window of the screw ④ is relatively larger than that of the screw ①, so a coil with a diameter of R2 needs to be used for detection in the III environment. Finally, the windows of the screws ② and ③ are the same and the largest, that is, a coil with a diameter of R3 needs to be used for detection in the II environment. In terms of the number of turns selection, it needs to be judged according to the screw diameter. The smaller the screw diameter, the stronger the magnetic field intensity signal the coil needs to provide during detection. Therefore, for the four anchor bolt specifications of M24, M30, M36, and M42, the number of turns of the coil can be selected as Nd, Nc, Nb, and Na respectively. The detection terminals corresponding to all detection conditions are shown in Table 1.

[0040] In summary, when this device faces different detection environments, according to the situations listed in Table 1, the control circuit turns on the corresponding positive and negative terminals of the circuit, and the magnetic field distribution can meet the detection requirements.

[0041] Table 1 Circuit conduction of line terminals corresponding to screws and environments

[0042]

[0043] The signal receiving module 9 integrates the HX6639 ultra-high-sensitivity linear Hall sensor, which is used to collect the magnetic field feedback signal of the target bolt and transmit this signal to the signal processing module 10.

[0044] The signal processing module 10 integrates the STM32F407 microprocessor. This microprocessor has the advantages of high performance and low power consumption. Through its fast and good signal processing ability, it can well ensure fast calculation on site and quickly obtain the data processing results. At the same time, considering the accuracy of the detection results, a detection standard library is set in this microprocessor system. The detection standards are set in 4 levels according to the magnetic field signal thresholds t, T, and H, namely "nut missing defect", "suspected nut missing defect", "suspected no nut missing defect", and "no nut missing defect", which are used to represent the actual detection results. As shown in Table 2.

[0045] Table 2 Detection standard library for anchor bolts of different diameters

[0046]

[0047] Note: i takes I, II, III;

[0048] By conducting experiments, the magnetic field strength thresholds t and T of different bolt specifications are statistically analyzed, and a magnetic field strength standard library for four bolt diameters in Table 1 is established. Considering that the magnetic field strength thresholds determined through experiments are affected by the limited number of tests, further improvement and correction are required. Therefore, this device allows operators to correct the thresholds through the human-computer interaction module 12 after a large number of actual detections, improving the environmental adaptability of this detection device; during the threshold setting process, three standard thresholds are set for each specification of bolt with and without a nut, corresponding to the standard magnetic field signals in three different detection environments, namely I, II, and III; at the same time, the median value of each specification of screw rod is the average value of the detection signal thresholds with and without a nut in each corresponding detection environment, that is, H = (T + t) / 2; here, the actual detection result is set as X; according to the standard library, when X <= t, the device displays "There is a defect of missing nut"; when t < X <= H, the device displays "Suspicious of having a defect of missing nut"; when H < X <= T, the device displays "Suspicious of no defect of missing nut"; when X > T, the device displays "No defect of missing nut".

[0049] The display module 11 uses an LCD1602 liquid crystal display screen to display the detection results of the device and the operation menu.

[0050] The human-computer interaction module 12 is provided with buttons to facilitate operators to select the corresponding detection mode of the device, modify the magnetic field signal thresholds t, T, H of the device, and record data such as detection results.

[0051] The power supply module 13 is a DC power supply that provides power to each module to ensure the stable operation of each module.

[0052] It should be noted that to solve the above technical problems, programming is required for the signal processing module 10 and the display module 11, and software is used. However, the software is only a part of implementing the technical solution of the present utility model, and its means are all prior arts. The key to solving the technical problems of the present utility model is to internally install coil modules with different numbers of turns and different radii to adapt to different bolts, so as to accurately perform non-destructive testing of bolts. This part is a new technology of shape, structure and their combination. Therefore, it shall not be determined that the content of this application does not belong to the protection object of the utility model on the grounds that software or programs need to be used.

Claims

1. A nondestructive testing device for foundation bolts of power transmission towers resistant to ferromagnetic interference, characterized in that: The invention comprises a magnetic field generating module (8) for generating a magnetic field, wherein a coil module (14) is provided in the magnetic field generating module (8), wherein a coil with multiple diameters and variable turns is provided in the coil module (14), wherein a signal receiving module (9) is provided at the center of the coil module (14), wherein the coil module (14) is electrically connected to an output end of a signal processing module (10), and wherein the signal receiving module (9) is electrically connected to an input end of the signal processing module (10), wherein magnetic field signals with different ranges and different intensities are generated by coils with different diameters and turns in the coil module (14), and act on materials in a detection area, and then a magnetic field feedback signal of a target bolt in the detection area is received by the detection signal receiving module (9), thereby determining the bolt condition.

2. The nondestructive testing device for foundation bolts of power transmission towers resistant to ferromagnetic interference according to claim 1 is characterized in that: The signal processing module (10) is communicatively connected to the display module (11).

3. The nondestructive testing device for foundation bolts of power transmission towers resistant to ferromagnetic interference according to claim 2 is characterized in that: The signal processing module (10) is electrically connected to the human-computer interaction module (12).

4. The nondestructive testing device for foundation bolts of power transmission towers resistant to ferromagnetic interference according to claim 3 is characterized in that: The multi-diameter variable-turn coil comprises a plurality of groups of coaxial coils with different diameters.

5. The nondestructive testing device for foundation bolts of power transmission towers resistant to ferromagnetic interference according to claim 4 is characterized in that: Each coil with a single diameter in the plurality of groups of coaxial coils with different diameters includes a plurality of groups of coils with different numbers of turns.

6. The nondestructive testing device for foundation bolts of power transmission towers resistant to ferromagnetic interference according to claim 5 is characterized in that: The multi-diameter variable turns coil comprises three groups of coils with diameters of R1, R2, and R3. <R2<R3。 7. The nondestructive testing device for foundation bolts of power transmission towers resistant to ferromagnetic interference according to claim 6 is characterized in that: Among the three groups of coils with diameters of R1, R2, and R3, each group of coils includes four coils with the number of turns being Na, Nb, Nc, and Nd respectively.

8. The nondestructive testing device for foundation bolts of power transmission towers resistant to ferromagnetic interference according to claim 7 is characterized in that: In the three groups of coils with diameters of R1, R2 and R3, the four coils in each group of coils include a common anode terminal and four cathode terminals with different numbers of turns. The anode terminals of the R1, R2 and R3 coils are respectively a first anode terminal (5), a second anode terminal (6) and a third anode terminal (7), and the cathode terminals with different numbers of turns in each group of coils are a Na cathode terminal (1), an Nb cathode terminal (2), an Nc cathode terminal (3) and an Nd cathode terminal (4).

9. The nondestructive testing device for foundation bolts of power transmission towers resistant to ferromagnetic interference according to claim 8, characterized in that: The magnetic field generating module (8), the signal receiving module (9), the signal processing module (10), the display module (11) and the human-computer interaction module (12) are electrically connected to the power supply module (13).

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