Method for identifying flaw detection sensitivity change by ultrasonic waves through interface waves

Abstract

The invention discloses a method for identifying flaw detection sensitivity change by ultrasonic waves through interface waves, and belongs to the technical field of nondestructive detection.The method comprises the steps that firstly, the initial reference height of primary interface waves is set, and the real-time height of the primary interface waves of multiple channels is collected in real time in the flaw detection process; and calculating the sensitivity attenuation of each channel by using a decibel difference algorithm. Furthermore, through statistical analysis of the arithmetic mean value and the standard deviation of the multichannel data, the attenuation amount and a preset threshold value are subjected to logic comparison: when the mean value exceeds the standard and the consistency is good, it is judged that systematic coupling deterioration occurs, and overall cleaning is triggered; when the consistency is poor due to attenuation of a specific channel, a local fault is judged, and an abnormal probe is positioned. According to the invention, sensitivity monitoring is converted from off-line verification to on-line real-time monitoring, the coupling water quality problem and the single probe fault can be accurately distinguished, the risk of batch leak detection is effectively avoided, and the quality control level and the production efficiency of flaw detection operation are improved.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology, specifically to a method for identifying changes in flaw detection sensitivity using ultrasonic waves through interface waves. Background Technology

[0002] In the metallurgical and oil and gas transportation industries, internal quality control of steel pipe products is a crucial aspect of ensuring project safety. Ultrasonic automatic flaw detection technology, due to its high detection speed, high sensitivity, and ability to detect internal cracks and other defects, is widely used in the quality inspection process before steel pipes leave the factory. In particular, the water immersion ultrasonic testing system, employing a rotating probe structure, uses water as the coupling medium for ultrasonic wave propagation. Through the combined motion of the probe rotating at high speed around the steel pipe and the steel pipe moving in a straight line, it can achieve full-coverage scanning of the pipe body and is currently the mainstream testing equipment on automated steel pipe production lines.

[0003] In existing automated ultrasonic flaw detection processes, ensuring that the sensitivity of the flaw detection system remains within the standard specified range is a core prerequisite for guaranteeing the reliability of test results. Typically, industrial sites use an offline calibration mode based on fixed time intervals to control sensitivity. Before each production shift or at set intervals (e.g., every 4 hours), operators feed sample tubes with pre-fabricated standard artificial defects (such as grooves or through holes) into the flaw detection equipment. The instrument's transmission voltage and reception gain are adjusted or confirmed based on the echo amplitude of the artificial defects. After a successful calibration until the next calibration, the system defaults to maintaining the acoustic performance of the equipment at the calibration state and continuously utilizes a circulating water system to establish a coupling layer for batch testing of steel pipes.

[0004] However, this offline verification mode based on fixed time intervals suffers from significant lag in practical applications, making it difficult to adapt to complex operating conditions during continuous production. Since the coupling water environment inside the rotating head is not constant, as a large number of steel pipes with oxide scale, rust, or oil continuously pass through the flaw detection host, detached impurities gradually mix into the circulating water, increasing turbidity, or directly adhere to the probe's radiating surface. These physical factors cause unpredictable attenuation of the ultrasonic wave transmission efficiency in the medium. Because existing technology lacks real-time online monitoring methods for acoustic energy transmission efficiency during flaw detection, if severe deterioration of the coupling water quality occurs during the interval between two manual verifications, the equipment cannot detect and respond in time, maintaining the original gain parameters. This results in the steel pipes being tested during that period actually being in a state of insufficient sensitivity, easily leading to batch defect omissions. Furthermore, this quality hazard is usually only discovered after the next sample tube verification fails, causing significant rework, re-testing, and production capacity losses. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for identifying changes in ultrasonic flaw detection sensitivity through interface waves. This method solves the problems of ultrasonic automatic flaw detection systems relying on fixed time intervals for sensitivity calibration, being unable to monitor sensitivity decline caused by coupled water quality deterioration in real time, and having difficulty distinguishing between systemic coupled environmental deterioration and single-channel probe failure, thus increasing the risk of missed detections or reducing production efficiency.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for identifying changes in ultrasonic flaw detection sensitivity via interface waves, wherein the method is applied to an automatic ultrasonic flaw detection system including a data processing and control unit, and the method includes the following steps: System initialization and reference sensitivity calibration steps: Before the flaw detection operation begins, set an initial reference height for the interface wave amplitude and use the initial reference height as the initial reference zero point for the system sensitivity; Multi-channel interface wave real-time monitoring and data acquisition steps: During the flaw detection process, the real-time height of the primary interface wave of the detection channel is locked and acquired in real time; Independent calculation steps for channel sensitivity attenuation: The data processing and control unit calculates the sensitivity attenuation at the current moment using a decibel difference algorithm based on the preset initial reference height and the real-time height of the first interface wave acquired in real time. The logical comparison steps for the critical threshold are as follows: The calculated sensitivity attenuation is compared with the preset alarm threshold. When the sensitivity attenuation reaches or exceeds the alarm threshold, it is determined that the system sensitivity has dropped to the critical point, and a corresponding status control signal is generated.

[0007] As a further improvement to the technical solution of the present invention, in the independent calculation step of the channel sensitivity attenuation, the sensitivity attenuation is calculated as follows: calculate the ratio of the initial reference height to the real-time height of the primary interface wave, take the logarithm of the ratio to the base 10, and multiply the logarithm by 20 to obtain the sensitivity attenuation; the alarm threshold is set to six decibels, and the alarm threshold corresponds to the real-time height of the primary interface wave dropping to 50% of the initial reference height.

[0008] As a further improvement to the technical solution of the present invention, the system initialization and reference sensitivity calibration steps specifically include: under the condition that the rotating head is running stably and the coupled water layer is established, adjusting the gain of the detection channel using a standard sample tube; by adjusting the digital display gain or waveform scaling factor, normalizing the amplitude of the primary interface wave in the defect-free area of ​​the detection channel to 80% of the full screen amplitude, thereby establishing the initial reference height as 80% of the full screen amplitude.

[0009] As a further improvement to the technical solution of the present invention, the multi-channel interface wave real-time monitoring and data acquisition steps specifically include: setting an interface wave tracking gate in the A-scan time domain waveform, the interface wave tracking gate being independent of the flaw detection gate used to detect defect waves; the data processing and control unit performing peak search within the time window of the interface wave tracking gate, locking the maximum value within the single pulse repetition frequency period as the real-time height of the first interface wave; performing a moving average calculation on the real-time height of the first interface wave for several consecutive periods, and using the calculated arithmetic mean as the effective measurement value.

[0010] As a further improvement to the technical solution of the present invention, the ultrasonic automatic flaw detection system includes multiple independent ultrasonic probes, each ultrasonic probe corresponding to an independent signal detection channel; the independent calculation step of the channel sensitivity attenuation is specifically performed as follows: calculating the sensitivity attenuation of each signal detection channel relative to the initial state; after the independent calculation step of the channel sensitivity attenuation, the method further includes a statistical analysis and differential comparison step of multi-channel data: extracting statistical features of the sensitivity attenuation of all signal detection channels at the same time, and calculating the arithmetic mean and standard deviation.

[0011] As a further improvement to the technical solution of the present invention, in the statistical analysis and differential comparison steps of the multi-channel data: the arithmetic mean is calculated by summing the sensitivity attenuation of all the signal detection channels and dividing by the total number of the signal detection channels; the standard deviation is calculated by: for each signal detection channel, calculating the difference between the sensitivity attenuation and the arithmetic mean, summing the squares of the differences corresponding to all the signal detection channels and dividing by the total number of the signal detection channels to obtain the variance, and finally taking the square root of the variance to obtain the standard deviation.

[0012] As a further improvement to the technical solution of the present invention, the method further includes an intelligent judgment and hierarchical response strategy step, wherein the intelligent judgment and hierarchical response strategy step specifically executes the first judgment logic: comparing the arithmetic mean with the global alarm threshold and comparing the standard deviation with the consistency tolerance threshold; when the arithmetic mean is greater than or equal to the global alarm threshold and the standard deviation is less than the consistency tolerance threshold, it is determined that the current state is in a systemic coupling deterioration state; the data processing and control unit generates a system maintenance command, controls the flaw detection line to stop running and prompts the overall cleaning and water replacement of the rotating head coupling water chamber.

[0013] As a further improvement to the technical solution of the present invention, the intelligent judgment and hierarchical response strategy step also executes a second judgment logic: when the conditions of the first judgment logic are not met, all the signal detection channels whose sensitivity attenuation is greater than or equal to the global alarm threshold are selected, and the corresponding channel index is recorded; if at least one of the channel indexes exists, it is determined that the current state is a local fault state; the data processing and control unit generates a channel check instruction and outputs the channel index, prompting to check a specific probe.

[0014] As a further improvement to the technical solution of the present invention, the ultrasonic automatic flaw detection system adopts the rotating head water immersion method for detection, and the rotating head is provided with a rotating head coupling water cavity to accommodate the coupling medium; the independent calculation step of the channel sensitivity attenuation is used to monitor the decrease in sound energy transmission efficiency caused by the accumulation of oxide scale and dust in the coupling water in the rotating head coupling water cavity.

[0015] As a further improvement to the technical solution of the present invention, after executing the operation corresponding to the system maintenance command or the channel inspection command, the method further includes a recovery and recalibration step: forcibly requiring the standard sample tube to be reintroduced; after confirming that the amplitude of the primary interface wave of all the detection channels has recovered to near the initial reference height, resetting the alarm state and releasing the system lockout.

[0016] This invention provides a method for identifying changes in flaw detection sensitivity using ultrasonic waves via interface waves. It offers the following advantages: 1. This invention solves the problem that traditional fixed-time interval verification modes cannot detect process changes in a timely manner by monitoring the change of interface wave amplitude in real time during the flaw detection process and using a decibel difference algorithm to quantitatively calculate the sensitivity attenuation of the current system. It can respond in a timely manner when the coupling water quality deteriorates or the probe surface is contaminated, resulting in a decrease in acoustic energy transmission efficiency. When the sensitivity drops to the critical alarm threshold, it automatically generates a control signal to cut off production risks. It effectively avoids the problem of batch missed detections that may occur during the interval between two manual verifications due to the hidden degradation of system performance. It realizes the transformation of flaw detection process quality control from post-event passive verification to real-time process monitoring.

[0017] 2. This invention collects multi-channel parallel data and introduces a statistical analysis mechanism to calculate the arithmetic mean and standard deviation of the sensitivity attenuation of all channels. Using these two statistical characteristics, it accurately distinguishes between systemic coupling medium deterioration and local probe hardware failure. When the problem is determined to be a water quality issue, an overall cleaning command is triggered. When the problem is determined to be a single-point failure, a specific channel is prompted for inspection. This hierarchical diagnostic strategy avoids unnecessary whole-system water replacement operations due to a single probe failure and also prevents incorrect troubleshooting of individual probes due to overall water quality problems. Thus, while ensuring detection quality, it reduces blind maintenance operations and downtime, and achieves rapid fault location and synergistic improvement in the efficiency of the flaw detection line.

[0018] 3. This invention establishes a quantitative mapping relationship between a change in interface wave height and the system sensitivity gain, transforming the abstract acoustic energy transmission efficiency into a specific decibel value that conforms to flaw detection standards. This eliminates the reliance on the operator's subjective experience in evaluating the coupling state. Furthermore, it sets mandatory recovery and recalibration steps after maintenance operations, requiring the system to be physically restored and the interface wave height to return to the reference value before the lockout can be released. This logical closed loop ensures that the system performance after each anomaly handling can be verified by physical sample tubes, eliminating the possibility of the equipment continuing to operate under incomplete maintenance conditions. This achieves objective quantitative evaluation of sensitivity indicators and closed-loop management of the entire process in automated flaw detection operations. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the rotating head coupling water cavity, guide sleeve, and sealing rubber of the present invention; Figure 2 This is a schematic diagram illustrating the principle of a single interface wave (T) signal when no defects are found in this invention; Figure 3 This is a schematic diagram illustrating the principle of interface wave (T) and defect wave (F) signals when a defect is detected according to the present invention. Figure 4 This is a schematic diagram illustrating the initial sensitivity of the present invention just before the alarm. Figure 5 This is a schematic diagram illustrating the improved 6dB flaw detection sensitivity of the present invention; Figure 6 This is a schematic diagram of the interface wave at 80% and the clean water cavity and probe of the present invention. Figure 7 This is a schematic diagram of the interface wave of 40% and the water cavity and probe that need to be cleaned in the present invention. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see the appendix Figure 1-7 This invention provides a method for identifying changes in flaw detection sensitivity using ultrasonic waves through interface waves.

[0022] To achieve sensitivity monitoring during the automatic ultrasonic flaw detection process of steel pipes, this embodiment employs a water immersion testing system based on a rotating ultrasonic probe. The system mainly includes a mechanical transmission unit, a coupling water circulation unit, an ultrasonic signal transceiver unit, and a data processing and control unit.

[0023] In terms of mechanical structure, the detection system employs a linear movement of the steel pipe and a rotating probe for scanning. The core component is the ultrasonic rotating main unit, which houses a rotating spindle. Water-retaining guide sleeves and sealing assemblies are located at both ends of this spindle, collectively forming a coupling water chamber that contains the coupling medium. During operation, an external water pump system continuously injects pressurized circulating water into this coupling water chamber. Utilizing the centrifugal force generated by the rotation, a stable coupling water layer is established between the outer surface of the steel pipe and the probe. This coupling water layer serves as the medium for ultrasonic wave propagation; however, due to its repeated use, it is prone to accumulating oxide scale and dust.

[0024] The ultrasonic signal transceiver unit includes components installed inside the rotating head. Each probe is an independent ultrasonic probe. These probes are evenly distributed along the circumference of the steel pipe, and each probe corresponds to an independent signal detection channel to achieve full coverage scanning of the steel pipe. Each probe contains a piezoelectric crystal, which vibrates and emits an ultrasonic beam under the excitation of high-frequency electrical pulses generated by the ultrasonic flaw detector. The excitation timing and signal transmission lines of each probe are conventional technical means known to those skilled in the art and will not be described in detail here.

[0025] The data processing and control unit (hereinafter referred to as the control unit) is electrically connected to the ultrasonic probes and mechanical transmission units of each of the above-mentioned independent channels. Specifically, the control unit can be composed of an industrial control computer (IPC), a programmable logic controller (PLC), and a multi-channel A / D acquisition card, and is used to perform multi-channel parallel signal acquisition, waveform analysis, gain calculation, and logic determination.

[0026] This embodiment monitors ultrasonic waves based on the physical propagation characteristics of the water immersion method. After the ultrasonic beam is emitted from the probe, it first propagates in the coupled water, reaching the interface between the water and the outer surface of the steel pipe (i.e., the water / steel interface). Due to the significant difference in acoustic impedance between the water and steel, part of the sound wave energy is reflected at the interface, forming a primary interface wave (also called the initial wave T); the other part of the sound wave energy is transmitted into the interior of the steel pipe wall and continues to propagate. If a defect exists within the pipe wall, the sound wave will generate a defect reflection wave (F) upon encountering the defect interface.

[0027] The control unit independently sets the interface wave gate on the time-domain waveform acquired by each channel, and tracks and measures the amplitude of the primary interface wave in real time. According to the physical propagation law of ultrasound, the amplitude of the primary interface wave characterizes the transmission efficiency of the sound wave in the coupling medium. During long-term flaw detection operations, oxide scale, floating dust, and oil on the surface of the steel pipe will gradually fall off and mix into the coupling water cavity. As the concentration of suspended particles in the coupling water increases, and as dirt adheres to the probe's radiating surface, the scattering and absorption attenuation of ultrasound in the water intensifies, resulting in a reduction in the incident sound energy reaching the surface of the steel pipe.

[0028] This attenuation of acoustic energy is systematically correlated: when the amplitude of the primary interface wave at the water / steel interface attenuates due to deteriorating coupling conditions, the acoustic energy transmitted into the steel pipe for defect detection also attenuates proportionally. In other words, the decrease in interface wave amplitude directly reflects a reduction in flaw detection sensitivity.

[0029] To quantify the aforementioned attenuation process, the control unit employs a decibel difference algorithm to establish a quantitative correlation between the interface wave height and sensitivity changes. The initial interface wave height is set as the reference height. Let the measured height of the interface wave at the current moment be... At this point, the sensitivity attenuation caused by the deterioration of coupling conditions It can be calculated using the following formula: This computational model establishes a numerical mapping between changes in physical wave height and system gain (dB). For example, when a single interface wave height is detected... When the sensitivity drops from the initial 80% to 40%, substituting into the above formula, the sensitivity attenuation is approximately 6dB. Based on this, the control unit determines that the system has reached the critical threshold for sensitivity alarm, without relying on repeated verification of actual defect test blocks. By monitoring the amplitude change of the interface wave once, the acoustic energy transmission efficiency of the entire detection system can be evaluated, thereby identifying the risk of missed detection caused by coupling water contamination or probe attachments.

[0030] Based on the above hardware architecture, the ultrasonic flaw detection sensitivity monitoring method described in this embodiment is executed by a data processing and control unit. This method converts the acoustic changes at the physical layer into quantifiable digital signals and achieves precise quality control through multi-channel logic analysis. The overall workflow includes the following steps: Step S100: System Initialization and Reference Sensitivity Calibration. Before starting batch steel pipe inspection operations, or after changing the coupling water and cleaning the rotating head, initial state calibration is performed. The control unit drives the mechanical transmission unit to transport the standard sample tube into the flaw detection area. With the rotating head running stably, the transmission voltage and receiving gain of each channel of the ultrasonic flaw detector are adjusted to ensure all... The amplitude of the primary interface wave in each independent detection channel reached the preset reference height. This reference height was then set. The initial baseline value for system sensitivity is 80% of the full-screen amplitude. At this point, it is confirmed that the system sensitivity is above the alarm sensitivity specified in the relevant standards.

[0031] Step S200: Real-time monitoring and data acquisition of multi-channel interface waves. During the automated flaw detection process of steel pipes, the control unit establishes the physical probe and logical channels based on the excitation timing sequence or rotary encoder signals of each channel. The one-to-one mapping relationship is established. In the A-scan time-domain waveform, the control unit sets an independent interface wave tracking gate (initial wave gate) within the time base range of the first interface wave occurrence. This gate is independent of the flaw detection gate used to detect defect waves. The system synchronously reads each channel at a preset frequency. The highest echo amplitude within the interface wave tracking gate For automatic tracking of gate position and peak capture, conventional threshold triggering or peak search algorithms in this field are used.

[0032] Step S300: Independent calculation of channel sensitivity attenuation. Based on the real-time waveform data obtained in step S200, and according to the principle of sound pressure transmission, the control unit calculates the sensitivity attenuation value of each channel relative to the initial state. The calculation formula is as follows: In the formula, Representing the The current sensitivity attenuation in decibels for each channel; The initial reference height set in step S100; This represents the current measured height of the channel. For example, if the interface wave height of a channel decreases from 80% to 40%, the system calculates that the sensitivity attenuation of the channel is approximately 6dB.

[0033] Step S400: Statistical analysis and differential comparison of multi-channel data. To distinguish between systemic environmental factors (such as overall contamination of the coupling water) and local hardware factors (such as single probe failure), the control unit performs statistical analysis and differential comparison of all data at the same time. Attenuation value of each channel Perform statistical analysis and calculate the arithmetic mean of the attenuation values ​​for all channels. and the dispersion index reflecting the differences between channels. Arithmetic mean The calculation formula is: Dispersion index The calculation formula is: Through the above calculations, we obtain the average characteristics representing the overall state of the system and the discrete characteristics representing the consistency of the channels.

[0034] Step S500, Intelligent Judgment and Graded Response Strategy: The control unit compares the calculated attenuation value, average value, and dispersion with the preset threshold and executes the following branch logic: First judgment logic: If the average attenuation value Exceeding the preset alarm threshold (e.g., set to 6dB), and the dispersion If the water quality is less than the preset consistency threshold, it indicates that each channel exhibits synchronous attenuation characteristics. The system determines that the current state is an overall deterioration of the coupled water quality, generates a water cavity cleaning signal, controls the flaw detection line to stop running, and prompts the system to perform overall cleaning and water replacement of the rotating head coupled water cavity.

[0035] Second judgment logic: If the average attenuation value Not exceeding the limit, but a specific channel exists. attenuation value Exceeding the alarm threshold leads to dispersion. If the value exceeds the consistency threshold, it indicates an abnormal channel status. The system determines the current status as a local probe malfunction or foreign object attachment, generates a channel inspection signal, and outputs the abnormal channel number. This prompts the operator to perform a targeted inspection of the specific probe.

[0036] The third judgment logic: If the attenuation value of all channels is lower than the alarm threshold, the system determines that the sensitivity is within the set requirement range, maintains the current production status, and returns to step S200 to continue the loop monitoring.

[0037] Step S600, Recovery and Recalibration: After performing the corresponding maintenance operations, the system requires re-execution of step S100. The operator must reinsert the standard sample tube to confirm that the primary interface wave height of all channels naturally recovers to the reference height. Nearby, only after recalibration verification will the control unit reset the alarm state and allow the automated flaw detection operation to continue.

[0038] To ensure the accuracy of the sensitivity monitoring baseline during the long-term operation of the ultrasonic flaw detection system, an initial state calibration procedure is performed before the formal commencement of batch steel pipe testing. This procedure aims to establish the initial baseline state for subsequent comparative analysis. The specific initial sensitivity calibration process is as follows: Step S110, Environmental Preparation and Sample Tube Introduction: Before calibration begins, confirm that the circulating water in the rotating head coupling water chamber is clean and that there is no oxide scale, oil, or air bubbles attached to the radiation surface of each ultrasonic probe. Control the mechanical transmission device to transport the standard sample tube with pre-set artificial defects to the rotating head flaw detection station. The material, specifications, and surface condition of the standard sample tube are consistent with the steel pipe to be inspected, and it is machined with artificial grooves or through holes that meet the flaw detection standards, serving as the physical reference for sensitivity adjustment.

[0039] Step S120: Setting the interface wave tracking gate. The control unit sets the interface wave tracking gate in the A-scan time-domain waveform of each channel. The starting position and width of the gate cover the time range corresponding to the ultrasonic wave reaching the steel pipe surface from the probe. The control unit uses an automatic peak search algorithm or threshold triggering logic to lock the gate on the first echo signal (i.e., the first interface wave) in the time-domain waveform that exceeds the preset threshold. When the steel pipe experiences slight jumping or eccentricity during rotation and advance, causing changes in the water layer thickness, the gate position can automatically shift with the movement of the interface wave on the time axis, ensuring that the interface wave is always within the gate monitoring range.

[0040] Step S130, Reference Wave Height Normalized adjustment, under the condition that the rotating head is operating at its rated speed and the coupled water layer is established stably, for Each independent detection channel is calibrated. First, the physical gain of each channel is adjusted according to the artificial defects on the standard sample tube to reach the standard-specified initial alarm sensitivity. Then, a preset gain value (6dB) is added as the production detection sensitivity. To facilitate intuitive calculation and unified monitoring of subsequent attenuation, while keeping the above-mentioned flaw detection sensitivity gain unchanged, the digital display gain or waveform scaling factor of each channel is adjusted to normalize the primary interface wave amplitude in the defect-free area to 80% of the full-screen amplitude. This value is defined as the initial reference height. ( =80), which is a reference value for energy transfer of the system under well-coupled conditions.

[0041] Step S140, Channel consistency verification and parameter locking. After completing all channels... After setting, the system calculates the consistency deviation of the interface wave height of each channel at the current time. If the deviation of each channel is within the preset tolerance range, it indicates that the performance consistency of each probe meets the operating requirements of the multi-channel differential alignment algorithm. The control unit then locks the current gain parameters and... The baseline value is stored in system memory and used to calculate the attenuation in subsequent real-time monitoring steps. If the minuend is changed to a different specification of steel pipe in subsequent production, steps S110 to S140 need to be repeated.

[0042] After initial sensitivity calibration and locking of reference parameters, the ultrasonic automatic flaw detection system enters the batch steel pipe inspection stage. In this stage, the data processing and control unit executes a real-time sensitivity monitoring program based on interface wave attenuation. This program processes the acquired waveform data and outputs quantitative sensitivity status indicators. The specific monitoring and calculation steps are as follows: Step S210: Real-time acquisition of interface wave amplitude. During the linear advance of the steel pipe and the rotating scan of the probe, the digital signal processor in the control unit processes the A-scan echo data of each independent channel in parallel. For each specific detection channel, a peak search operation is performed within the time domain window according to the interface wave tracking gate set in step S120. This operation compares the amplitude of all sampling points within the gate range, locks the maximum value within the single pulse repetition frequency period, and marks it as the real-time single interface wave height. To eliminate instantaneous fluctuations caused by random electronic noise or tiny bubbles, the control unit is equipped with a moving average algorithm, which calculates the moving average over several consecutive periods (e.g., 5 to 10 periods). The numerical values ​​are calculated, and the resulting arithmetic mean is used as the valid measurement input value at that moment.

[0043] Step S310: The sensitivity attenuation calculation is performed, and the control unit retrieves the preset initial reference height from the storage unit. And read the real-time measurement value obtained in step S210. The decibel difference calculation is performed, which aims to convert the proportional change in amplitude into a decibel value. The specific calculation formula is as follows: In the formula: This is the percentage of the normalized interface wave height in the initial calibration state stored in the system memory; in this embodiment, this setting is 80%. The percentage of interface wave height after real-time monitoring and filtering during the flaw detection process; This is the calculated decrease in decibels in the current system sensitivity relative to the initial calibration state.

[0044] Through this step, the control unit converts the acquired analog signal feature values ​​into digital gain differences for logical judgment in real time.

[0045] Step S320: Logical comparison of critical thresholds. The system's internal register has a preset limit threshold for the allowable attenuation of sensitivity. In this embodiment, this threshold is set to 6dB. When suspended particles accumulate in the coupling water due to recycling or when dirt adheres to the probe surface, the interface wave height... It will exhibit a decreasing numerical characteristic, when real-time monitoring shows When the voltage drops from the initial 80% to 40%, the control unit performs the above formula calculation and obtains a result of approximately 6dB. At this point, the control unit will calculate the voltage in real time. The value is compared with the preset alarm threshold, and once the calculation result is obtained... (Right now The control unit generates a status flag bit to indicate that the actual flaw detection sensitivity of the channel has been reduced to the critical point of the initial alarm sensitivity.

[0046] Step S330: Independent channel recording of data. The above acquisition and calculation process is performed within the system. Each detection channel executes independently and in parallel. The control unit allocates independent storage space in the data storage area based on the channel's physical address or logical index number, recording the corresponding physical channel. The numerical data structure establishes a one-to-one correspondence between the calculation results and the physical probes, enabling the system to independently track the acoustic energy transmission status of each probe at a specific angle. These independently stored attenuation data, based on index numbers, serve as the foundational input data for subsequent steps involving multi-channel differential analysis and fault source localization.

[0047] After acquiring independent sensitivity attenuation data for each channel, the control unit further executes a multi-channel differential comparison and intelligent diagnostic program. This program performs horizontal comparison of multiple parallel data streams through statistical analysis to classify and locate fault sources. The specific steps are as follows: Step S410: Statistical feature extraction of multi-channel data. The control unit reads data from the storage area at the same time. Sensitivity attenuation sequence of each detection channel To quantify the overall level of acoustic energy transmission inside the rotating head and the consistency between channels at the current moment, the control unit calculates the arithmetic mean and standard deviation of the data sequence.

[0048] Arithmetic mean The formula used to characterize the global decay trend of the system is as follows: Standard deviation The consistency deviation used to characterize the attenuation state of each channel, serving as a key indicator for determining the fault type, is calculated using the following formula: In the formula, The total number of flaw detection channels in use. For the first Sensitivity attenuation value for each channel.

[0049] Step S510, logical determination of systemic coupling medium deterioration, the control unit calculates the arithmetic mean With preset global alarm threshold (In this embodiment, the value is set to 6 dB) The comparison is performed, and the standard deviation is also considered. Consistency tolerance threshold (For example, set to 1.5dB) for comparison.

[0050] When the system detects that the following logical condition is met: The system is currently in a state of deteriorating coupling. This state indicates that the rotating head is in a state of... All probes showed a similar degree of sensitivity decrease, consistent with the characteristics of increased overall turbidity of the coupling water and uniform attenuation of sound waves in the medium due to uniform distribution of suspended particles. At this time, the control unit generates a system maintenance command and sends a shutdown request signal to the main control PLC of the flaw detection line through the I / O interface or communication bus. At the same time, it triggers the control relay of the automatic cleaning system to perform water replacement and cleaning actions in the internal cavity of the rotating head.

[0051] Step S520: Logical screening of local hardware faults. If the conditions of step S510 above are not met, the control unit enters the local anomaly scanning process.

[0052] The control unit iterates through the attenuation values ​​of all channels in the sequence. Filter out all that meet the requirements Channel index If at least one such channel exists, the system determines that it is currently in a partial fault state, which indicates that the coupled water quality may still be within acceptable limits, but the third... The radiating surface of the probe may have absorbed air bubbles or foreign objects, or the probe and its connecting lines may have experienced performance degradation, resulting in a significantly lower acoustic energy transmission efficiency than other normal channels.

[0053] Step S530: Local fault location output, based on the abnormal channel index selected in step S520. ( (This may be a single or multiple values). The control unit generates a channel check command, which maps the physical number of the abnormal channel to the alarm display area of ​​the human-machine interface (HMI), visually indicating the specific fault probe location in graphical or textual form. Based on this prompt, the operator only needs to check the first... The probe is used for targeted inspection and cleaning, without the need for water replacement and maintenance of the entire water circulation system.

[0054] Based on the above diagnostic judgment logic, when the flaw detection system is in different abnormal states, specific cleaning control procedures are executed, and the implementation effect of the monitoring method is verified in combination with actual production data. The specific graded maintenance execution and application verification process is as follows: Step S610: Execution and feedback of graded maintenance instructions. For the state determined as systemic coupling deterioration in step S510, the data processing and control unit sends a global cleaning request signal to the main control PLC of the flaw detection production line via the industrial fieldbus or digital I / O interface. After receiving the signal, the main control PLC controls the transmission roller to stop running and outputs control voltage to drive the electric drain valve of the coupling water circulation system to open, discharging turbid coupling water. At the same time, the system starts the high-pressure clean water flushing circuit to flush the internal cavity of the rotating head, the sealing guide sleeve, and the surface of all probes. After the cleaning action is completed, the system controls the water injection valve to re-inject clean coupling water into the cavity. For the state determined as local fault in step S520, the control unit maps the physical location of the abnormal channel to the display terminal of the operating console. The operator, according to the instructions, cleans the surface foreign matter or removes air bubbles only for the specific probe. After completing any of the above physical maintenance actions, the control unit forcibly jumps back to step S100, requiring the operator to reintroduce the standard sample tube and recalibrate the reference sensitivity until the interface wave height of each channel returns to the reference value. Only when the system is nearby can the lockout be lifted and automated production resume.

[0055] Step S620: Verify the effect and compare data. To verify the actual effect of the method described in this embodiment in adapting to different steel pipe surface conditions and preventing missed detections, three steel pipes of different specifications and surface conditions were selected for comparative testing. The test background was set as follows: according to the conventional flaw detection process specifications, the production line is set with a fixed sample pipe calibration cycle of 4 hours.

[0056] The first set of embodiments selected steel pipes with a specification of 60.32mm × 4.83mm. This batch of steel pipes had less surface dust and oxide scale, and a lower rate of coupled water contamination. Monitoring was performed using the method described in this embodiment. Data showed that when continuous production reached the 4-hour mark, the system calculated a sensitivity attenuation of approximately 4dB, which had not yet reached the 6dB alarm threshold. Based on the attenuation trend, the actual time for the interface wave height to drop to 40% (i.e., triggering a 6dB alarm) was estimated to be approximately 5 hours. Under this condition, although a traditional fixed 4-hour calibration cycle could meet the quality requirements, it indicates that the system still has sufficient sensitivity margin in the 4th hour. This method allows the equipment to continue operating for 5 hours before cleaning, thereby increasing the effective operating time of the equipment while ensuring quality.

[0057] The second set of embodiments used steel pipes with a specification of 88.9mm × 6.45mm. This batch of steel pipes had poor surface quality, with a large amount of loose oxide scale and floating dust. As flaw detection proceeded, the oxide scale quickly detached and became suspended in the coupling water. Monitoring data showed that at the 3-hour mark of production, the interface wave height... The sensitivity had decreased from the initial 80% to below 40%, with a decrease of 6dB, prompting the control unit to immediately trigger a shutdown and cleaning alarm. In contrast, if the traditional 4-hour fixed calibration mode were used, the system would continue running for another hour with insufficient sensitivity. By the end of the 4th hour, when manual calibration was performed, the measured sensitivity decrease had reached 7dB, exceeding the standard's allowable fluctuation range. This meant that steel pipes produced between the 3rd and 4th hours had a risk of missed inspections and required full rework. This method effectively cut off the risk in the 3rd hour, preventing a batch quality incident.

[0058] The third set of embodiments selected a steel pipe with a specification of 114.3mm×6.88mm. Under similar surface quality conditions, when the monitoring system reached the 3.5-hour node, it captured that the interface wave height dropped to 40%, and the calculated sensitivity attenuation reached 6dB (compared to the potential attenuation of 6.5dB at the 4-hour node). The system then triggered an alarm and shut down.

[0059] The aforementioned implementation data shows that the degree of oxide scale peeling off the steel pipe surface directly determines the contamination rate of the coupling water, thus causing the sensitivity decay to exhibit a non-linear time characteristic. The method described in this embodiment transforms the quality control approach from time-based fixed-cycle verification to state-based real-time process monitoring, by monitoring the height of a single interface wave. Relative to the baseline value The system can dynamically adapt to the working conditions of different pipe materials: when the water quality deteriorates rapidly (as in the second and third embodiments), it can intervene in advance to alarm and prevent low-sensitivity operation; when the water quality is good (as in the first embodiment), it can extend the cleaning interval, thus achieving synergistic optimization of flaw detection quality control and production efficiency.

[0061] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for identifying changes in flaw detection sensitivity using ultrasonic waves via interface waves, characterized in that, Includes the following steps: System initialization and reference sensitivity calibration steps: Before the flaw detection operation begins, set an initial reference height for the interface wave amplitude and use the initial reference height as the initial reference zero point for the system sensitivity; Multi-channel interface wave real-time monitoring and data acquisition steps: During the flaw detection process, the real-time height of the primary interface wave of the detection channel is locked and acquired in real time; Independent calculation steps for channel sensitivity attenuation: The data processing and control unit calculates the sensitivity attenuation at the current moment using a decibel difference algorithm based on the preset initial reference height and the real-time height of the first interface wave acquired in real time. The logical comparison steps for the critical threshold are as follows: The calculated sensitivity attenuation is compared with the preset alarm threshold. When the sensitivity attenuation reaches or exceeds the alarm threshold, it is determined that the system sensitivity has dropped to the critical point, and a corresponding status control signal is generated.

2. The method for identifying changes in ultrasonic flaw detection sensitivity via interface waves according to claim 1, characterized in that, In the independent calculation step of the channel sensitivity attenuation, the sensitivity attenuation is calculated as follows: Calculate the ratio of the initial reference height to the real-time height of the first interface wave, take the logarithm of the ratio to the base 10, and multiply the logarithm by 20 to obtain the sensitivity attenuation. The alarm threshold is set to six decibels, which corresponds to the real-time height of the first interface wave dropping to fifty percent of the initial reference height.

3. The method for identifying changes in ultrasonic flaw detection sensitivity via interface waves according to claim 1, characterized in that, The system initialization and reference sensitivity calibration steps specifically include: With the rotating head running stably and the coupled water layer established, the gain of the detection channel is adjusted using a standard sample tube; By adjusting the digital display gain or waveform scaling factor, the amplitude of the primary interface wave in the defect-free area of ​​the detection channel is normalized to 80% of the full-screen amplitude, thereby establishing the initial reference height as 80% of the full-screen amplitude.

4. The method for identifying changes in ultrasonic flaw detection sensitivity via interface waves according to claim 1, characterized in that, The specific steps of the multi-channel interface wave real-time monitoring and data acquisition include: An interface wave tracking gate is set in the A-scan time domain waveform, the interface wave tracking gate being independent of the flaw detection gate used to detect defect waves; The data processing and control unit performs peak search within the time window of the interface wave tracking gate and locks the maximum value within the single pulse repetition frequency period as the real-time height of the first interface wave. The real-time height of the interface wave over several consecutive periods is calculated using a moving average, and the calculated arithmetic mean is used as the effective measurement value.

5. The method for identifying changes in ultrasonic flaw detection sensitivity via interface waves according to claim 1, characterized in that, The ultrasonic automatic flaw detection system includes multiple independent ultrasonic probes, each of which corresponds to an independent signal detection channel. The independent calculation step of the channel sensitivity attenuation is specifically performed as follows: calculate the sensitivity attenuation of each signal detection channel relative to the initial state; After the independent calculation step of the channel sensitivity attenuation, the method further includes a statistical analysis and differential comparison step of multi-channel data: extracting statistical features of the sensitivity attenuation of all signal detection channels at the same time, and calculating the arithmetic mean and standard deviation.

6. The method for identifying changes in ultrasonic flaw detection sensitivity via interface waves according to claim 5, characterized in that, In the statistical analysis and differential comparison steps of the multi-channel data: The arithmetic mean is calculated by summing the sensitivity attenuation of all the signal detection channels and dividing by the total number of the signal detection channels. The standard deviation is calculated as follows: for each signal detection channel, the difference between the sensitivity attenuation and the arithmetic mean is calculated. The sum of the squares of the differences corresponding to all signal detection channels is divided by the total number of signal detection channels to obtain the variance. Finally, the square root of the variance is taken to obtain the standard deviation.

7. The method for identifying changes in ultrasonic flaw detection sensitivity via interface waves according to claim 6, characterized in that, The method further includes an intelligent judgment and hierarchical response strategy step, which specifically executes the first judgment logic: The arithmetic mean is compared with the global alarm threshold, and the standard deviation is compared with the consistency tolerance threshold; When the arithmetic mean is greater than or equal to the global alarm threshold and the standard deviation is less than the consistency tolerance threshold, it is determined that the current state is in a state of systemic coupling deterioration. The data processing and control unit generates system maintenance instructions, controls the flaw detection line to stop running, and prompts for overall cleaning and water replacement of the rotating head coupling water chamber.

8. The method for identifying changes in ultrasonic flaw detection sensitivity via interface waves according to claim 7, characterized in that, The intelligent judgment and hierarchical response strategy step also executes a second judgment logic: When the conditions of the first determination logic are not met, all signal detection channels with a sensitivity attenuation greater than or equal to the global alarm threshold are selected, and the corresponding channel index is recorded. If at least one of the aforementioned channel indices exists, it is determined that the current state is a partial fault. The data processing and control unit generates channel inspection instructions and outputs the channel index, prompting for inspection of a specific probe.

9. The method for identifying changes in ultrasonic flaw detection sensitivity via interface waves according to claim 1, characterized in that, The ultrasonic automatic flaw detection system adopts the rotating head water immersion method for detection, and the rotating head is provided with a rotating head coupling water cavity to contain the coupling medium; The independent calculation step of the channel sensitivity attenuation is used to monitor the decrease in acoustic energy transmission efficiency caused by the accumulation of oxide scale and dust in the coupling water within the rotating head coupling water cavity.

10. The method for identifying changes in ultrasonic flaw detection sensitivity via interface waves according to claim 8, characterized in that, After executing the operation corresponding to the system maintenance command or the channel check command, the method further includes a recovery and recalibration step: It is mandatory to re-inject the standard sample tube; After confirming that the amplitude of the primary interface wave in all the detection channels has recovered to near the initial reference height, reset the alarm status and release the system lockout.

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