Ultrasonic testing system and method for defects of fan main shaft under in-situ non-disassembly condition

Abstract

The application discloses a kind of for in situ without disassembly condition fan main shaft defect ultrasonic testing system, comprising: control analysis module, signal acquisition device;Signal acquisition device includes rack, rack is equipped with with the guide rail that the end face of fan main shaft to be detected cooperates, guide rail is movably connected with the movable seat that moves up and down along track, vertically driving mechanism is equipped on rack and drives movable seat, movable seat is equipped with the measuring seat that moves in horizontal direction, movable seat is equipped with the horizontal driving mechanism that drives measuring seat, measuring seat is equipped with self-releasing self-receiving ultrasonic probe;Signal acquisition device further includes remove noise module, feature extraction module, defect positioning module.The application further includes the detection method of the detection system.

Description

TECHNICAL FIELD

[0001] The application relates to an ultrasonic detection system for defects of a fan main shaft under the condition of in-situ non-disassembly and a detection method thereof, and belongs to the technical field of nondestructive testing. BACKGROUND

[0002] The fan main shaft is a core component of a wind driven generator, is subjected to influences of external environment and complex and changeable loads in operation, and is prone to cracks and defects due to cyclic fatigue. The cracks gradually expand under continuous stress, and finally lead to breakage of the main shaft, seriously threatening the service life of the wind driven generator and the safety of workers. Although the traditional disassembly detection and offline in-situ detection can detect defects, there are defects such as slow detection, long downtime, high cost and the like, and therefore, it is necessary to realize in-situ online detection of defects of the fan main shaft under the condition of non-disassembly. SUMMARY

[0003] The application aims to solve the technical problem of providing an ultrasonic detection system for defects of a fan main shaft under the condition of in-situ non-disassembly.

[0004] To solve the above technical problem, the technical scheme adopted by the application is as follows: an ultrasonic detection system for defects of a fan main shaft under the condition of in-situ non-disassembly, comprising: a control analysis module and a signal acquisition device.

[0005] The signal acquisition device comprises a rack, the rack is provided with guide rails matched with end faces of fan main shafts to be detected, the guide rails are movably connected with movable seats moving up and down along the guide rails, the rack is provided with a vertical driving mechanism driving the movable seats, the movable seats are provided with measuring seats moving in a horizontal direction, the movable seats are provided with horizontal driving mechanisms driving the measuring seats, and the measuring seats are provided with self-emitting and self-receiving ultrasonic probes.

[0006] The signal acquisition device further comprises a noise removal module, a feature extraction module and a defect positioning module.

[0007] The noise removal module is used for eliminating random noise and interference in the ultrasonic signal, so that the signal is clearer.

[0008] The feature extraction module is used for extracting features related to defects of the main shaft from the denoised ultrasonic signal, so as to improve the strength of the signal and the sensitivity of detection.

[0009] The defect positioning module is used for analyzing the features of the main shaft defects in the ultrasonic signal, and positioning the defects according to the feature position coordinates.

[0010] The defect positioning according to the characteristic position coordinates specifically comprises: setting a variable threshold according to the signal amplitude, dynamically adjusting the threshold according to the maximum amplitude in the signal, the threshold maintaining a certain proportion with the maximum amplitude, and accurately detecting and positioning the characteristic wave in different amplitude ranges through the variable threshold, so that the position of the defect is effectively located.

[0011] The signal acquisition device and the control analysis module are both provided with a communication module to perform signal acquisition and processing on the grid-shaped divided areas of the main shaft end face one by one under the execution instruction operation issued by the control analysis module, and transmit the acquired and processed signals to the control analysis module.

[0012] The rack is provided with a vertical range finder for detecting the vertical position of the movable seat and a horizontal range finder for detecting the horizontal position of the ultrasonic probe.

[0013] As a preferred scheme, the communication module is a wireless communication module, which is used for transmitting the processed signals to the remotely arranged control analysis module for analysis and processing, and transmitting the operation instruction of the control analysis module to the signal acquisition device.

[0014] As a preferred scheme, the guide rail is a circular guide rail matched with the main shaft end face of the fan to be detected, the vertical driving mechanism comprises a circular driving rack arranged beside the circular guide rail, the movable seat is provided with a driving motor, a driving gear matched with the driving rack is arranged on the output shaft of the driving motor, and the horizontal driving mechanism is a horizontally arranged telescopic electric push rod arranged on the movable seat, and the movable end of the electric push rod is provided with the measuring seat.

[0015] As a preferred scheme, the control analysis module is connected with a display device.

[0016] Another technical problem to be solved by the application is to provide a detection method of the ultrasonic detection system for defects of the main shaft of the fan under the condition of in-situ non-disassembly.

[0017] To solve the above technical problems, the technical scheme adopted by the application is as follows:

[0018] Speed calibration of the main shaft material: the ultrasonic probe is placed on the main shaft end face, a short pulse ultrasonic signal is emitted, the reflected signal is received by the probe, the speed v of the ultrasonic wave in the main shaft material is calculated through the measured main shaft length and the propagation time, v=2l / t; in the formula, l is the main shaft length, and t is the time for the ultrasonic wave to propagate back and forth in the main shaft;

[0019] A pulse signal is emitted to the defect-free main shaft end face to obtain a waveform diagram of the defect-free main shaft end face, so as to facilitate subsequent comparison and analysis with the defect waveform.

[0020] The end face is divided by a discrete grid and identified by a row-column order two-dimensional coordinate;

[0021] According to the end face grid identification, the ultrasonic probe is remotely controlled by a signal acquisition device to collect signals, the self-emission self-reception probe emits ultrasonic signals along the generatrix direction of the spindle, and the probe receiving element receives the reflected echo signals;

[0022] The signal received by the ultrasonic probe is denoised to reduce background noise and non-structural interference, and enhance the clarity and stability of the signal;

[0023] The denoised signal is feature extracted, the important information in the spindle defect signal is extracted by analyzing the frequency spectrum characteristics and time domain characteristics of the ultrasonic signal, so as to improve the signal strength and detection sensitivity;

[0024] By comparing the waveform graphs with and without defects, the characteristics of the spindle defects in the ultrasonic signal are analyzed, the defect is positioned according to the characteristic position coordinates, and the degree of the defect is judged according to the characteristic amplitude.

[0025] As a preferred scheme, the signal received by the ultrasonic probe receiving element is analyzed, including:

[0026] The denoising process is specifically: selecting a suitable wavelet basis function and a decomposition layer number, wavelet decomposing the signal to obtain approximation coefficients and detail coefficients; the detail coefficients are threshold processed to remove noise, and then the coefficients after threshold processing are inverse wavelet transformed to reconstruct the denoised ultrasonic signal;

[0027] The feature extraction is specifically: the denoised ultrasonic echo signal is subjected to generalized cross threshold synchronous compression wavelet transform, the signal is decomposed into different frequency bands and time components to extract features from the time-frequency domain, the wavelet coefficients after decomposition are threshold processed to highlight the characteristics of the defect echo signal, and then the threshold processed decomposition results are synchronously compressed to further highlight the abnormalities and defects in the echo signal.

[0028] The beneficial effects of the present application are:

[0029] 1.The application provides a kind of fan main shaft defect ultrasonic testing system under the condition of in situ without disassembly, the system includes: control analysis module, signal acquisition device;Signal acquisition device includes noise removal module, feature extraction module, defect positioning module;Control analysis module and signal acquisition device are provided with wireless communication module;Signal acquisition device can remotely control probe position, by matching with end face grid, the rapid positioning of defect can be realized, and technical personnel are facilitated to carry out timely repair or further refinement detection;Noise removal module, feature extraction module and defect positioning module analyze signal, remove noise and interference in signal, extract signal characteristics, realize accurate positioning of defect;Wireless communication module transmits the signal processed to the control analysis module of remote setting and carries out analysis and processing, and the operation instruction of control analysis module is transmitted to signal acquisition device;The system greatly improves operation efficiency and response speed, and provides an efficient and convenient solution for the safe operation and maintenance of fan main shaft.

[0030] 2.The application provides a kind of fan main shaft defect ultrasonic testing method under the condition of in situ without disassembly, the method adopts main shaft end face grid discretization method, and the end face is divided by discrete grid and is marked with two-dimensional coordinates, so as to facilitate subsequent signal acquisition;The method uses self-emission and self-reception type ultrasonic probe, integrates transmission and reception functions in a single probe, simplifies system design and assembly cost;The application adopts dynamic peak value proportion threshold detection method to realize the positioning of defect, the method uses the proportional relationship of peak value to adaptively adjust threshold, so that the main shaft defect signal can be effectively identified in complex working environment;Compared with existing disassembly detection or offline in situ detection, the method can realize online detection and evaluation of fan main shaft defect under the condition of not disassembly, and has significant advantages in implementation convenience and economy. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is the main shaft structure size and detection area schematic diagram in the embodiment of the application.

[0032] Figure 2 It is the schematic diagram of defect positioning according to waveform feature position coordinates in the embodiment of the application.

[0033] Figure 3 It is the schematic diagram of judging defect degree according to waveform feature amplitude size in the embodiment of the application.

[0034] Figure 4 It is the structure schematic diagram of a kind of fan main shaft defect ultrasonic testing system under the condition of in situ without disassembly provided by the application.

[0035] Figure 5 It is the schematic diagram of signal acquisition device in a kind of fan main shaft defect ultrasonic testing system under the condition of in situ without disassembly provided by the application.

[0036] In the figure: 1 frame, 2 guide rail, 3 movable seat, 4 drive rack, 5 drive motor, 6 drive gear, 7 electric push rod, 8 measuring seat, 9 ultrasonic probe; 10 vertical range finder, 11 horizontal range finder. DETAILED DESCRIPTION

[0037] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0038] As Figures 1-5 shown, an ultrasonic detection system for fan main shaft defects under the condition of in-situ without disassembly, comprising: a control analysis module, a signal acquisition device; the control analysis module is connected with a display device.

[0039] The signal acquisition device comprises a frame 1, the frame 1 is provided with a circular guide rail 2 matched with the end face of the fan main shaft to be detected, the guide rail 2 is movably connected with a movable seat 3 moving up and down along the track, and the frame 1 is provided with a vertical driving mechanism driving the movable seat 3. The vertical driving mechanism comprises a circular drive rack 4 arranged beside the circular guide rail 2, the movable seat 3 is provided with a drive motor 5, and the output shaft of the drive motor 5 is provided with a drive gear 6 matched with the drive rack 4. The movable seat 3 is provided with a horizontally arranged telescopic electric push rod 7, the movable end of the electric push rod 7 is provided with a measuring seat 8, and the measuring seat 8 is provided with a self-emitting and self-receiving ultrasonic probe 9; the frame 1 is provided with a vertical range finder 10 detecting the vertical position of the movable seat 3 and a horizontal range finder 11 detecting the horizontal position of the ultrasonic probe 9.

[0040] The signal acquisition device further comprises a noise removal module, a feature extraction module and a defect positioning module.

[0041] The noise removal module is used for eliminating random noise and interference in the ultrasonic signal, so that the signal is clearer.

[0042] The feature extraction module is used for extracting the features related to the main shaft defects from the de-noised ultrasonic signal, so as to improve the strength of the signal and the sensitivity of the detection.

[0043] The defect positioning module is used for analyzing the features in the ultrasonic signal which are judged as the main shaft defects, and positioning the defects according to the feature position coordinates.

[0044] The signal acquisition device and the control analysis module are both provided with a communication module to perform signal acquisition and processing on the main shaft end face grid division area one by one through the control analysis module issuing execution instruction operation, and transmit the acquisition and processing signals to the control analysis module.

[0045] The communication module is a wireless communication module, which is used for transmitting the processed signals to the remotely arranged control analysis module for analysis and processing, and transmitting the operation instructions of the control analysis module to the signal acquisition device.

[0046] The detection method of the fan main shaft defect ultrasonic detection system under the in-situ undismounted condition is as follows:

[0047] Speed calibration of the main shaft material: the ultrasonic probe 9 is placed on the end face of the main shaft, a short pulse ultrasonic signal is emitted, and after the probe receives the reflected signal, the speed v of the ultrasonic wave in the main shaft material is calculated based on the measured length of the main shaft and the propagation time: v = 2l / t; in the formula, l is the length of the main shaft; t is the time for the ultrasonic wave to propagate back and forth in the main shaft;

[0048] The material of the fan main shaft detected in this embodiment is 42CrMo4, the length of the main shaft is 2690mm, the detection surface is the upper end face of the main shaft, the diameter of the end face is 1500mm, and the structural size and the detection area are as shown in Figure 2 After speed calibration and calculation, the propagation speed of the ultrasonic wave in the main shaft material is 5900m / s.

[0049] By emitting a pulse signal to the end face of the defect-free main shaft, a waveform diagram of the defect-free main shaft is obtained, so as to facilitate subsequent comparison and analysis with the defect waveform;

[0050] The end face is divided into a grid and identified by row and column order; for example, the first row and the first column are (1, 1), the first row and the second column are (1, 2), and so on. When the ultrasonic probe 9 moves between adjacent grids, the ultrasonic probe 9 requires a 15% to 20% repeat coverage rate to ensure comprehensive coverage and continuity of the signal.

[0051] According to the grid identification of the end face, the ultrasonic probe 9 is remotely controlled by the signal acquisition device to collect signals, and the self-emitting and self-receiving probe emits ultrasonic signals along the generatrix direction of the main shaft. When the signal encounters a defect during propagation, the probe receiving element receives the reflected echo signal;

[0052] The signal received by the ultrasonic probe 9 is denoised, and the denoising process is as follows: selecting an appropriate wavelet basis function and a decomposition level, wavelet decomposition is performed on the signal to obtain approximation coefficients and detail coefficients; the detail coefficients are threshold processed to remove noise, and then the coefficients after threshold processing are inverse wavelet transformed to reconstruct the denoised ultrasonic signal; thereby reducing background noise and non-structural interference, enhancing the clarity and stability of the signal;

[0053] Feature extraction is performed on the denoised signal, specifically: a generalized cross-threshold synchronous compression wavelet transform is performed on the denoised ultrasonic echo signal. By decomposing the signal into different frequency bands and time components, features are extracted from the time-frequency domain. The decomposed wavelet coefficients are thresholded to highlight the characteristics of the defect echo signal. The thresholded decomposition result is then synchronously compressed to further highlight anomalies and defects in the echo signal. By analyzing the spectral characteristics and time domain characteristics of the ultrasonic signal, important information from the spindle defect signal is extracted to improve the signal strength and detection sensitivity.

[0054] By comparing the waveforms with and without defects, the features of the ultrasonic signal that are judged as spindle defects are analyzed and the defect is located according to the feature position coordinates, such as Figure 2 As shown in the figure, specifically: a variable threshold is set according to the signal amplitude, and the threshold is dynamically adjusted according to the maximum amplitude in the signal. The threshold and the maximum amplitude are kept in a certain ratio. Through this variable threshold, the characteristic waves within different amplitude ranges can be accurately detected and located, thereby effectively locating the position of the defect. The degree of the defect is judged according to the characteristic amplitude, such as Figure 3 shown.

[0055] The above embodiments are merely illustrative of the principles and effects of the present invention, as well as some embodiments of its application, and are not intended to limit the present invention. It should be noted that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A system for ultrasonic testing of a fan main shaft defect under in-situ non-destructive condition, characterized in that, The utility model relates to a kind of wind turbine main shaft defect ultrasonic detection system and method, including: Control analysis module, signal acquisition device; Signal acquisition device includes rack, rack is equipped with with the guide rail that the end face of the fan main shaft to be detected cooperates, guide rail is movably connected with the movable seat that moves along track up and down, rack is equipped with the vertical drive mechanism of drive movable seat, movable seat is equipped with the measurement seat that moves in horizontal direction, movable seat is equipped with the horizontal drive mechanism of drive measurement seat, measurement seat is equipped with self-releasing self-receiving ultrasonic probe; Signal acquisition device further includes noise removal module, feature extraction module, defect positioning module; Noise removal module is used to eliminate random noise and interference in ultrasonic signal, so that signal is clearer; Feature extraction module is used to extract features related to main shaft defects from denoised ultrasonic signal, to improve signal strength and detection sensitivity; Defect positioning module is used to analyze features in ultrasonic signal that are judged as main shaft defects, and to position defects according to feature position coordinates; According to feature position coordinates, a variable threshold is set according to signal amplitude, the threshold is dynamically adjusted according to the maximum amplitude in the signal, the threshold and the maximum amplitude maintain a certain proportion, and the variable threshold can realize accurate detection and positioning of features in different amplitude range, so as to effectively position the position of defect; Signal acquisition device and control analysis module are both equipped with communication module to transmit collected and processed signals to control analysis module through control analysis module issuing execution instruction operation to collect and process signals of main shaft end face grid division area one by one. The rack is equipped with a vertical range finder for detecting the vertical position of the detection movable seat and a horizontal range finder for detecting the horizontal position of the ultrasonic probe.

2. A system for ultrasonic testing of a fan shaft defect in situ without disassembly, according to claim 1, characterized in that, The communication module is a wireless communication module for transmitting processed signals to a remotely located control analysis module for analysis and processing, and transmitting operation instructions from the control analysis module to the signal acquisition device.

3. A system for ultrasonic testing of a fan shaft for defects in situ without disassembly, according to claim 1, characterized in that, The guide rail is a circular guide rail matched with the end face of the fan main shaft to be detected, the vertical drive mechanism includes a circular drive rack arranged beside the circular guide rail, the movable seat is equipped with a drive motor, the output shaft of the drive motor is equipped with a drive gear matched with the drive rack, and the horizontal drive mechanism is a telescopic electric push rod arranged horizontally on the movable seat, and the movable end of the electric push rod is equipped with the measurement seat.

4. A system for ultrasonic testing of a fan shaft defect in situ without disassembly, according to any one of claims 1-3, characterized in that, The control analysis module is connected to a display device.

5. A detection method of the in-situ wind turbine main shaft defect ultrasonic detection system without disassembly, specifically as follows: Speed calibration of main shaft material: place the ultrasonic probe on the end face of the main shaft, emit a short pulse ultrasonic signal, receive the reflected signal by the probe, measure the length of the main shaft and the propagation time, calculate the speed of ultrasonic wave in the main shaft material v: v=2l / t; In the formula, l is the length of the main shaft, and t is the time of ultrasonic wave propagation in the main shaft for one round trip. Emit a pulse signal to the end face of the defect-free main shaft to obtain the waveform diagram of the defect-free main shaft, so as to compare and analyze with the defect waveform subsequently; Discretization grid division is adopted for the end face, and two-dimensional coordinate identification is carried out in row and column order. According to the end face grid mark, the ultrasonic probe is remotely controlled to collect signals by a signal collecting device, the self-emission and self-reception probe is used to emit ultrasonic signals along the generatrix direction of the main shaft, and the signals are reflected or diffracted when encountering defects in the propagation process, and the probe receiving element receives the reflected echo signals; The signals received by the ultrasonic probe are denoised to reduce background noise and non-structural interference, and to enhance the clarity and stability of the signals; The denoised signals are feature extracted, important information in the main shaft defect signal is extracted by analyzing the frequency spectrum characteristics and time domain characteristics of the ultrasonic signals, so as to improve the signal intensity and detection sensitivity; By comparing the waveform graphs with and without defects, the characteristics of the main shaft defects in the ultrasonic signals are analyzed, the defects are positioned according to the characteristic position coordinates, and the degree of the defects is judged according to the characteristic amplitude.

6. A method of inspecting a fan shaft of a wind turbine in situ without disassembly, using the system according to claim 5, characterized in that The signals received by the ultrasonic probe receiving element are analyzed, including: The denoising process is specifically: selecting a suitable wavelet basis function and a decomposition layer number, wavelet decomposing the signal to obtain approximation coefficients and detail coefficients; the detail coefficients are threshold processed to remove noise, and then the coefficients after threshold processing are inverse wavelet transformed to reconstruct the denoised ultrasonic signals; The feature extraction is specifically: the denoised ultrasonic echo signals are generalized cross threshold synchronous compression wavelet transformed, the signals are decomposed into different frequency bands and time components to extract features from the time-frequency domain, the wavelet coefficients after decomposition are threshold processed to highlight the characteristics of the defect echo signals, and then the threshold processed decomposition results are synchronous compressed to further highlight the abnormalities and defects in the echo signals.

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