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

Abstract

The invention discloses an ultrasonic detection system for defects of a main shaft of a fan under an in-situ non-disassembly condition. The ultrasonic detection system comprises a control analysis module and a signal acquisition device, the signal acquisition device comprises a rack, the rack is provided with a guide rail matched with the end face of the main shaft of the fan to be detected, the guide rail is movably connected with a movable seat moving up and down along the guide rail, the rack is provided with a vertical driving mechanism for driving the movable seat, and the movable seat is provided with a measuring seat moving in the horizontal direction. A horizontal driving mechanism for driving the measuring seat is arranged on the movable seat, and a self-transmitting and self-receiving ultrasonic probe is arranged on the measuring seat; the signal acquisition device further comprises a noise removal module, a feature extraction module and a defect positioning module. The invention further comprises a detection method of the detection system.

Description

Technical Field

[0001] The invention relates to an ultrasonic detection system and a detection method for fan main shaft defects under the condition of in-situ non-disassembly, belonging to the technical field of non-destructive detection. Background Art

[0002] As the core component of a wind turbine, the main shaft of a wind turbine is subjected to the influence of the external environment and complex and variable loads during operation, and is prone to cracks and defects due to cyclic fatigue. Cracks will gradually expand under continuous stress, and may eventually cause the main shaft to break, seriously threatening the service life of the wind turbine and the safety of the staff. Although traditional disassembly inspection and offline in-situ inspection can detect defects, they have the disadvantages of slow detection, long downtime, and high cost. Therefore, it is very necessary to realize in-situ online inspection of wind turbine main shaft defects without disassembling the machine. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an ultrasonic detection system for fan main shaft defects under the condition of in-situ non-disassembly.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: an ultrasonic detection system for fan main shaft defects without disassembly in situ, including: a control and analysis module, a signal acquisition device;

[0005] The signal acquisition device comprises a frame, a guide rail matched with the end face of the main shaft of the fan to be detected is arranged on the frame, a movable seat moving up and down along the rail is movably connected to the guide rail, a vertical driving mechanism driving the movable seat is arranged on the frame, a measuring seat moving horizontally is arranged on the movable seat, a horizontal driving mechanism driving the measuring seat is arranged on the movable seat, and a self-emitting and self-receiving ultrasonic probe is arranged on the measuring seat;

[0006] The signal acquisition device also includes a noise removal module, a feature extraction module, and a defect location module;

[0007] The noise removal module is used to eliminate random noise and interference in ultrasonic signals to make the signals clearer;

[0008] A feature extraction module is used to extract features related to the spindle defect from the denoised ultrasonic signal to improve the signal strength and detection sensitivity;

[0009] Defect location module, used to analyze the features of the main shaft defects in the ultrasonic signal and locate the defects according to the feature position coordinates;

[0010] The signal acquisition device and the control and analysis module are both provided with communication modules to perform signal acquisition and processing on the grid-divided areas of the spindle end face one by one through the execution instruction operation issued by the control and analysis module, and transmit the acquired and processed signals to the control and analysis module.

[0011] As a preferred solution, the communication module is a wireless communication module, which is used to transmit the processed signal to a remotely set control and analysis module for analysis and processing, and transmit the operation instructions of the control and analysis module to the signal acquisition device.

[0012] As a preferred solution, a vertical rangefinder for detecting the vertical position of the movable seat and a horizontal rangefinder for detecting the horizontal position of the ultrasonic probe are provided on the frame.

[0013] As a preferred solution, the guide rail is a circular guide rail that matches the end face of the main shaft of the fan to be tested, the vertical drive mechanism includes a circular drive rack arranged next to the circular guide rail, the movable seat is provided with a drive motor, and the output shaft of the drive motor is provided with a drive gear that matches the drive rack, and the horizontal drive mechanism is a horizontally arranged retractable electric push rod set on the movable seat, and the movable end of the electric push rod is provided with the measuring seat.

[0014] As a preferred solution, the control and analysis module is connected to a display device.

[0015] Another technical problem to be solved by the present invention is to provide a detection method for an ultrasonic detection system for fan main shaft defects under in-situ, non-disassembly conditions.

[0016] In order to solve the above technical problems, the technical solution adopted by the present invention is: a detection method of the ultrasonic detection system for fan main shaft defects without disassembling the machine in situ, which is specifically as follows:

[0017] Calibrate the sound velocity of the spindle material: Place the ultrasonic probe on the end face of the spindle, and emit a short pulse ultrasonic signal. After the probe receives the reflected signal, the sound velocity v of the ultrasonic wave in the spindle material is calculated by measuring the spindle length and propagation time: In the formula, l is the length of the main axis; t is the time it takes for the ultrasonic wave to propagate back and forth on the main axis;

[0018] By transmitting a pulse signal to the non-defective spindle end face, a non-defective waveform is obtained to facilitate subsequent comparative analysis with the defective waveform;

[0019] The end surface is divided into discrete grids and marked with two-dimensional coordinates in row and column order;

[0020] According to the end face grid mark, the ultrasonic probe is remotely controlled by the signal acquisition device to collect signals. The ultrasonic signal is transmitted along the main axis generatrix direction by a self-transmitting and self-receiving probe. When the signal encounters defects during the propagation process, it is reflected or diffracted, and the probe receiving element receives the reflected echo signal.

[0021] De-noise the signal received by the ultrasonic probe to reduce background noise and non-structural interference, and enhance the clarity and stability of the signal;

[0022] Perform feature extraction on the denoised signal, and extract important information from the spindle defect signal by analyzing the spectrum characteristics and time domain characteristics of the ultrasonic signal to improve the signal strength and detection sensitivity;

[0023] By comparing the waveforms with defects and those without defects, the features of the ultrasonic signal that are judged as spindle defects are analyzed, the defects are located according to the feature position coordinates, and the degree of the defects is determined according to the feature amplitude.

[0024] As a preferred solution, analyzing the signal received by the ultrasonic probe receiving element includes:

[0025] The denoising process is specifically as follows: selecting a suitable wavelet basis function and decomposition layer number, performing wavelet decomposition on the signal to obtain approximation coefficients and detail coefficients; performing threshold processing on the detail coefficients to remove noise, and then performing inverse wavelet transform on the coefficients after threshold processing to reconstruct the denoised ultrasonic signal;

[0026] The feature extraction is specifically as follows: performing generalized cross-threshold synchronous compression wavelet transform on the denoised ultrasonic echo signal, extracting features from the time-frequency domain by decomposing the signal into different frequency bands and time components, performing threshold processing on the decomposed wavelet coefficients to highlight the features of the defect echo signal, and then performing synchronous compression on the decomposition result after the threshold processing to further highlight the anomalies and defects in the echo signal;

[0027] The defect positioning according to the characteristic position coordinates is specifically as follows: 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, characteristic waves within different amplitude ranges can be accurately detected and positioned, thereby effectively positioning the defect.

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

[0029] 1. The present invention provides an ultrasonic detection system for defects in a fan main shaft in situ without disassembling the machine, the system comprising: a control and analysis module, a signal acquisition device; the signal acquisition device comprises a noise removal module, a feature extraction module, and a defect location module; the control and analysis module and the signal acquisition device are both provided with a wireless communication module; the signal acquisition device can remotely control the probe position, and by matching with the end face grid, can quickly locate the defects, facilitating technicians to carry out timely repairs or further refine the detection; the noise removal module, the feature extraction module and the defect location module analyze the signal, remove noise and interference in the signal, extract signal features, and achieve accurate positioning of the defect; the wireless communication module transmits the processed signal to the remotely set control and analysis module for analysis and processing, and transmits the operation instructions of the control and analysis module to the signal acquisition device; the system greatly improves the operating efficiency and response speed, and provides an efficient and convenient solution for the safe operation and maintenance of the fan main shaft.

[0030] 2. The present invention provides an ultrasonic detection method for fan main shaft defects in situ without disassembling the machine. The method adopts a main shaft end face grid discretization method, divides the end face into a discretized grid and performs two-dimensional coordinate identification to facilitate subsequent signal collection; the method adopts a self-transmitting and self-receiving ultrasonic probe, which integrates the transmitting and receiving functions in a single probe, simplifying the system design and assembly costs; the present invention adopts a dynamic peak ratio threshold detection method to locate the defect. The method uses the proportional relationship of the peak value to adaptively adjust the threshold, so that the main shaft defect signal can still be effectively identified in a complex working environment; compared with the existing disassembly detection or offline in-situ detection, this method can realize online detection and evaluation of fan main shaft defects without disassembling the machine, and has significant advantages in implementation convenience and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the spindle structure dimensions and the detection area in an embodiment of the present invention.

[0032] Figure 2 It is a schematic diagram of defect location based on characteristic position coordinates of a waveform diagram in an embodiment of the present invention.

[0033] Figure 3 It is a schematic diagram of judging the degree of defects according to the characteristic amplitude of the waveform in an embodiment of the present invention.

[0034] Figure 4 The present invention is a schematic structural diagram of a fan main shaft defect ultrasonic detection system provided by the present invention in situ without disassembling the machine.

[0035] Figure 5 It is a schematic diagram of a signal acquisition device in a fan main shaft defect ultrasonic detection system provided by the present invention under the condition of in-situ non-disassembly of the machine.

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

[0037] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0038] like Figure 1-5 As shown, a fan main shaft defect ultrasonic detection system for in-situ non-disassembly conditions includes: a control and analysis module, a signal acquisition device; the control and analysis module is connected to a display device.

[0039] The signal acquisition device includes a frame 1, on which a circular guide rail 2 matching the end face of the main shaft of the wind turbine to be detected is provided, on which a movable seat 3 moving up and down along the rail is movably connected, and on which a vertical driving mechanism driving the movable seat 3 is provided. The vertical driving mechanism includes a circular driving rack 4 arranged beside the circular guide rail 2, on which a driving motor 5 is provided, and on which the output shaft of the driving motor 5 is provided a driving gear 6 matching the driving rack 4. The movable seat 3 is provided with a horizontally arranged retractable electric push rod 7, on which a measuring seat 8 is provided at the movable end, and on which a self-transmitting and self-receiving ultrasonic probe 9 is provided; the frame 1 is provided with a vertical rangefinder 10 for detecting the vertical position of the movable seat 3 and a horizontal rangefinder 11 for detecting the horizontal position of the ultrasonic probe 9.

[0040] The signal acquisition device also includes a noise removal module, a feature extraction module, and a defect location module;

[0041] The noise removal module is used to eliminate random noise and interference in ultrasonic signals to make the signals clearer;

[0042] A feature extraction module is used to extract features related to the spindle defect from the denoised ultrasonic signal to improve the signal strength and detection sensitivity;

[0043] Defect location module, used to analyze the features of the main shaft defects in the ultrasonic signal and locate the defects according to the feature position coordinates;

[0044] The signal acquisition device and the control and analysis module are both provided with communication modules to perform signal acquisition and processing on the grid-shaped divided areas of the spindle end face one by one through the execution instruction operation issued by the control and analysis module, and transmit the acquired and processed signals to the control and analysis module.

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

[0046] The detection method of the ultrasonic detection system for fan main shaft defects under the above-mentioned in-situ non-disassembly condition is as follows:

[0047] The sound velocity of the spindle material is calibrated: the ultrasonic probe 9 is placed on the end face of the spindle, and a short pulse ultrasonic signal is emitted. After the probe receives the reflected signal, the sound velocity v of the ultrasonic wave in the spindle material is calculated by measuring the spindle length and propagation time: In the formula, l is the length of the main axis; T is the time it takes for the ultrasonic wave to propagate back and forth on the main axis;

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

[0049] By transmitting a pulse signal to the non-defective spindle end face, a non-defective waveform is obtained to facilitate subsequent comparative analysis with the defective waveform;

[0050] The end surface is divided into discrete grids and marked with two-dimensional coordinates in 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 is required to have a repetitive coverage rate of 15% to 20% to ensure full coverage and continuity of the signal.

[0051] According to the end face grid mark, the ultrasonic probe 9 is remotely controlled by the signal acquisition device to collect signals. The ultrasonic signal is emitted along the main axis generatrix direction by a self-transmitting and self-receiving probe. When the signal encounters a defect during the propagation process, it is reflected or diffracted, and the probe receiving element receives the reflected echo signal.

[0052] The signal received by the ultrasonic probe 9 is subjected to denoising processing, and the denoising processing specifically includes: selecting a suitable wavelet basis function and decomposition layer number, performing wavelet decomposition on the signal, and obtaining an approximation coefficient and a detail coefficient; performing threshold processing on the detail coefficient to remove noise, and then performing an inverse wavelet transform on the coefficient after threshold processing, and reconstructing the denoised ultrasonic signal; thereby reducing background noise and non-structural interference, and enhancing the clarity and stability of the signal;

[0053] The feature extraction of the denoised signal is performed, 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, features are extracted from the time-frequency domain, the decomposed wavelet coefficients are subjected to threshold processing, the features of the defect echo signal are highlighted, and then the decomposition result after threshold processing is subjected to synchronous compression to further highlight the anomalies and defects in the echo signal; by analyzing the spectral characteristics and time domain characteristics of the ultrasonic signal, important information in the main shaft 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 in 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-mentioned embodiments are only illustrative of the principles and effects of the invention, as well as some embodiments of its application, and are not intended to limit the invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the invention, and all of these belong to the protection scope of the invention.

Claims

1. An ultrasonic detection system for fan main shaft defects without disassembly, characterized in that: include: Control analysis module, signal acquisition device; The signal acquisition device comprises a frame, a guide rail matched with the end face of the main shaft of the fan to be detected is arranged on the frame, a movable seat moving up and down along the rail is movably connected to the guide rail, a vertical driving mechanism driving the movable seat is arranged on the frame, a measuring seat moving horizontally is arranged on the movable seat, a horizontal driving mechanism driving the measuring seat is arranged on the movable seat, and a self-emitting and self-receiving ultrasonic probe is arranged on the measuring seat; The signal acquisition device also includes a noise removal module, a feature extraction module, and a defect location module; The noise removal module is used to eliminate random noise and interference in ultrasonic signals to make the signals clearer; A feature extraction module is used to extract features related to the spindle defect from the denoised ultrasonic signal to improve the signal strength and detection sensitivity; Defect location module, used to analyze the features of the main shaft defects in the ultrasonic signal and locate the defects according to the feature position coordinates; The signal acquisition device and the control and analysis module are both provided with communication modules to perform signal acquisition and processing on the grid-shaped divided areas of the spindle end face one by one through the execution instruction operation issued by the control and analysis module, and transmit the acquired and processed signals to the control and analysis module.

2. The ultrasonic detection system for fan main shaft defects in situ without disassembly as claimed in claim 1 is characterized in that: The communication module is a wireless communication module, which is used to transmit the processed signal to a remotely arranged control and analysis module for analysis and processing, and transmit the operation instruction of the control and analysis module to the signal acquisition device.

3. The ultrasonic detection system for fan main shaft defects in situ without disassembly as claimed in claim 1 is characterized in that: The frame is provided with a vertical rangefinder for detecting the vertical position of the movable seat and a horizontal rangefinder for detecting the horizontal position of the ultrasonic probe.

4. The ultrasonic detection system for fan main shaft defects in situ without disassembly as claimed in claim 1 is characterized in that: The guide rail is a circular guide rail that matches the end face of the main shaft of the fan to be tested. The vertical drive mechanism includes a circular drive rack arranged next to the circular guide rail. A drive motor is provided on the movable seat, and a drive gear that matches the drive rack is provided on the output shaft of the drive motor. The horizontal drive mechanism is a horizontally arranged retractable electric push rod set on the movable seat, and the movable end of the electric push rod is provided with the measuring seat.

5. A fan main shaft defect ultrasonic detection system for in-situ non-disassembly conditions according to any one of claims 1 to 4, characterized in that: The control and analysis module is connected to a display device.

6. A method for detecting fan main shaft defect ultrasonic detection system under in-situ non-disassembly conditions according to any one of claims 1 to 5, specifically as follows: Calibrate the sound velocity of the spindle material: Place the ultrasonic probe on the end face of the spindle, and emit a short pulse ultrasonic signal. After the probe receives the reflected signal, the sound velocity v of the ultrasonic wave in the spindle material is calculated by measuring the spindle length and propagation time: In the formula, l is the length of the main axis; t is the time it takes for the ultrasonic wave to propagate back and forth on the main axis; By transmitting a pulse signal to the non-defective spindle end face, a non-defective waveform is obtained to facilitate subsequent comparative analysis with the defective waveform; The end surface is divided into discrete grids and marked with two-dimensional coordinates in row and column order; According to the end face grid mark, the ultrasonic probe is remotely controlled by the signal acquisition device to collect signals. The ultrasonic signal is transmitted along the main axis generatrix direction by a self-transmitting and self-receiving probe. When the signal encounters defects during the propagation process, it is reflected or diffracted, and the probe receiving element receives the reflected echo signal. De-noise the signal received by the ultrasonic probe to reduce background noise and non-structural interference, and enhance the clarity and stability of the signal; Perform feature extraction on the denoised signal, and extract important information from the spindle defect signal by analyzing the spectrum characteristics and time domain characteristics of the ultrasonic signal to improve the signal strength and detection sensitivity; By comparing the waveforms with defects and those without defects, the features of the ultrasonic signal that are judged as spindle defects are analyzed, the defects are located according to the feature position coordinates, and the degree of the defects is determined according to the feature amplitude.

7. A detection method of the ultrasonic detection system for fan main shaft defects without disassembly as claimed in claim 6, characterized in that: Analyze the signal received by the ultrasonic probe receiving element, including: The denoising process is specifically as follows: selecting a suitable wavelet basis function and decomposition layer number, performing wavelet decomposition on the signal to obtain approximation coefficients and detail coefficients; performing threshold processing on the detail coefficients to remove noise, and then performing inverse wavelet transform on the coefficients after threshold processing to reconstruct the denoised ultrasonic signal; The feature extraction is specifically as follows: performing generalized cross-threshold synchronous compression wavelet transform on the denoised ultrasonic echo signal, extracting features from the time-frequency domain by decomposing the signal into different frequency bands and time components, performing threshold processing on the decomposed wavelet coefficients to highlight the features of the defect echo signal, and then performing synchronous compression on the decomposition result after the threshold processing to further highlight the anomalies and defects in the echo signal; The defect positioning according to the characteristic position coordinates is specifically as follows: 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, characteristic waves within different amplitude ranges can be accurately detected and positioned, thereby effectively positioning the defect.

Images