Chain crack on-line monitoring device and method for plate chain machine

Abstract

This invention provides an online monitoring device and method for chain cracks in a plate chain conveyor. The device includes: a frame straddling the chain to be monitored; a position detection mechanism mounted on the frame for detecting the position and movement sequence of individual chain links; a striking excitation mechanism mounted on the frame for applying mechanical striking excitation to the chain links; a sound acquisition unit mounted on the frame for acquiring acoustic signals generated by the striking excitation mechanism; and a control and analysis unit electrically connected to the position detection mechanism, the striking excitation mechanism, and the sound acquisition unit, for controlling the action of the striking excitation mechanism based on the position and movement sequence detected by the position detection mechanism, and for monitoring chain cracks based on the acoustic signals. This solution effectively improves the timeliness and accuracy of monitoring.

Description

Technical Field

[0001] This invention relates to the field of equipment condition monitoring technology, and in particular to an online monitoring device and method for chain cracks in plate chain machines. Background Technology

[0002] With the continuous development of industrial automation, plate chain conveyors, as core equipment for material conveying, are widely used in industrial production processes such as solid-state fermentation of liquor. During long-term operation, the plate chain conveyor chains are frequently subjected to alternating loads such as tension, bending, and impact, making them highly susceptible to fatigue cracks at the openings or edges of the chain plates. To ensure the safe and continuous operation of the production line, it is necessary to monitor the health status of the plate chain conveyor chains.

[0003] Currently, the health status monitoring of chain conveyors mainly relies on manual inspection. Maintenance personnel need to periodically stop the machine to check for cracks on the chain plate surface by visual inspection. This method has limitations: manual inspection cycles are long and it is difficult to cover every chain plate; visual inspection is not sensitive to early micro-cracks, and material adhesion on the chain plate surface further reduces visibility; stopping the machine for inspection affects production efficiency. Summary of the Invention

[0004] This invention provides an online monitoring device and method for cracks in the chain of a plate chain machine, in order to solve the above-mentioned technical problems.

[0005] The present invention provides an online monitoring device for chain cracks in a plate chain machine, comprising: The rack is straddled on the chain to be monitored; A position detection mechanism, mounted on the frame, is used to detect the position and movement sequence of individual chain links on the chain; A striking excitation mechanism is mounted on the frame and is used to apply mechanical striking excitation to the chain plates of the chain. A sound acquisition unit, mounted on the frame, is used to acquire acoustic signals generated by the striking excitation mechanism; The control and analysis unit is electrically connected to the position detection mechanism, the striking excitation mechanism, and the sound acquisition unit, respectively. It is used to control the action of the striking excitation mechanism according to the position and movement sequence detected by the position detection mechanism, and to monitor the chain cracks according to the soundprint signal.

[0006] In one embodiment of the present invention, the position detection mechanism includes: An angle sensor, which is mounted on the frame; A deflection rod is installed at the output end of the angle sensor, with one end of the deflection rod away from the angle sensor extending into the pins of the chain; When the chain moves, the deflection rod is pushed by the pin and deflects around the mounting point of the angle sensor as the center of rotation. The angle sensor detects the deflection angle. When the deflection rod deflects to a preset angle, the deflection rod disengages from the pin and resets under the action of gravity.

[0007] In one embodiment of the present invention, the striking excitation mechanism includes a reciprocating drive assembly and a striking head. The reciprocating drive assembly is used to reciprocate in a direction perpendicular to the surface of the chain plate. The striking head is installed at the output end of the reciprocating drive assembly and is used to apply a force parallel to the axial direction of the pin to the chain plate.

[0008] In one embodiment of the present invention, the reciprocating drive component includes: case, The first coil is fixedly installed inside the housing; The second coil is arranged on the same axis as the first coil and is fixed to the housing. A central hole is opened at the center of the second coil along the axis. A movable component is disposed between the first coil and the second coil, and can reciprocate axially with the first coil as the first coil and the second coil are energized and de-energized. One end of the movable component passes through the central hole and is connected to the striking head.

[0009] In one embodiment of the present invention, the striking excitation mechanism is disposed on the return section of the chain and located above or on the side of the chain.

[0010] In one embodiment of the present invention, the sound acquisition unit includes a microphone array, wherein the microphone array includes a plurality of microphones.

[0011] In one embodiment of the present invention, the sound acquisition unit is arranged within a range of 30-100cm around the striking point of the striking excitation mechanism, and the sound pickup direction of at least one microphone is directed towards the striking point.

[0012] In one embodiment of the present invention, the striking head is made of an alloy material that matches the acoustic impedance of the chain plate material.

[0013] In one embodiment of the present invention, the online monitoring device for chain cracks in the plate chain machine further includes an alarm module, which is used to issue an alarm signal when the control and analysis unit determines that the chain has cracked.

[0014] This invention also provides an online monitoring method for cracks in the chain of a plate chain machine, applied to the aforementioned online monitoring device for cracks in the chain of a plate chain machine. The method includes: The acoustic signature signal is transformed and processed to extract the energy distribution of the characteristic frequency bands in order to determine the energy amplitude, spectral sharpness, and energy ratio of the high-frequency band of crack scattering to the fundamental frequency band. The energy amplitude, spectral sharpness, and energy ratio of the high-frequency band of crack scattering are compared with the standard parameters of the crack to determine the chain crack data. The chain crack data includes no crack, micro-crack, obvious crack, and severe crack.

[0015] The beneficial effects of this invention are as follows: The online monitoring device and method for chain cracks in a plate chain machine proposed in this invention detects the running status and position of the chain through the setting of a position detection mechanism, which facilitates the accurate striking of the target area by the striking excitation mechanism. The acoustic signal of the striking is collected by the sound acquisition unit and then analyzed by the control and analysis unit to determine whether cracks exist on the chain.

[0016] This application abandons the passive monitoring approach. The position detection mechanism can capture the instantaneous movement of each chain plate through a specific position in real time and accurately, and output a high-precision synchronization signal containing position and movement timing, solving the technical problem of difficulty in locking the impact point in dynamically operating equipment. Compared with manual monitoring in existing technologies, it can effectively improve the timeliness and accuracy of monitoring. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0018] In the attached diagram: Figure 1 This is a schematic diagram of the structure of an online monitoring device for chain cracks in a plate chain machine according to an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the reciprocating drive component provided in one embodiment of the present invention.

[0020] The attached figures are labeled as follows: Rack 1 Chain 2, chain plate 201, pin 202 Position detection mechanism 3, fixed bracket 301, angle sensor 302, deflection rod 303, The components include: a striking excitation mechanism 4, a reciprocating drive assembly 41, a housing 411, a first coil 412, a second coil 413, a moving part 414, and a striking head 42. Control Analysis Unit 5 Sound acquisition unit 6. Detailed Implementation

[0021] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0022] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the shape, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0023] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0024] In industrial production processes such as solid-state fermentation of baijiu (Chinese liquor), the plate chain conveyor is a core piece of equipment for material conveying, playing an irreplaceable role in multiple production stages, including the transport of cooked grains, grain lees, and fermentation mash. The plate chain conveyor chain 2 is composed of several chain plates 201 connected by pins 202. During long-term continuous operation, it frequently endures alternating loads such as tension, bending, and impact, making it highly susceptible to fatigue cracks at the openings or edges of the chain plates 201. If these cracks propagate and cause the chain plates 201 to break, it will result in severe downtime for maintenance, material accumulation, and consequently affect the overall production cycle and process stability.

[0025] The root cause of these technical defects lies in the fact that traditional monitoring methods heavily rely on manual, periodic shutdowns for inspection. However, manual visual inspection is not only inefficient and unable to cover every link of the chain plate 201, but also extremely insensitive to early-stage micro-cracks. Furthermore, material adhering to the surface of the chain plate 201 further reduces visibility. In addition, the operating environment of chain conveyors is typically characterized by high temperature, high humidity, high dust levels, and strong mechanical background noise. Conventional passive vibration sensors or machine vision solutions often face difficulties in signal decoupling and lens contamination under these harsh conditions, causing even subtle crack features to be completely masked by environmental noise.

[0026] To address the aforementioned technical issues, this application abandons the passive listening approach and transforms an uncontrollable random noise environment into a controllable excitation response test environment by actively applying mechanical excitations with known characteristics. This significantly improves the signal-to-noise ratio and enables accurate, online, and automatic identification of early-stage micro-cracks in the chain 2 of the plate chain machine.

[0027] See Figure 1 This application provides an online monitoring device for chain cracks in a plate chain machine. The device is integrated into one unit and mainly includes a frame 1, a position detection mechanism 3, a striking excitation mechanism 4, a sound acquisition unit 6, and a control and analysis unit 5.

[0028] Specifically, the frame 1 is mounted across the chain 2 of the plate chain machine to be monitored. As the supporting carrier of the entire monitoring device, the frame 1 is firmly mounted across the chain 2 of the plate chain machine, providing a relatively independent and stable working platform for each functional module, and minimizing the direct transmission of vibration of the plate chain machine body to the monitoring device.

[0029] The position detection mechanism 3 is mounted on the frame 1 and is used to detect the position and movement sequence of a single chain plate 201 on the chain 2 of the plate chain machine. When the chain 2 of the plate chain machine moves continuously, the position detection mechanism 3 can capture the moment when each chain plate 201 passes through a specific position in real time and accurately, and output a synchronization signal containing the position and movement sequence, thus solving the problem of difficulty in locking the striking point in dynamic operating equipment.

[0030] The striking excitation mechanism 4 is mounted on the frame 1 and is used to apply mechanical striking excitation to the chain plates 201 of the chain conveyor 2. Upon receiving a trigger command from the control and analysis unit 5, the striking excitation mechanism 4 applies transient mechanical striking excitation to the chain plates 201 of the chain conveyor 2 under controlled conditions. This actively applied mechanical striking is equivalent to injecting a wideband excitation energy into the chain plates 201, forcing them to generate free-dampening vibrations and radiate sound waves outwards. If there are micro-cracks inside the chain plates 201, the friction and nonlinear contact at the crack interface will cause high-frequency scattering and energy redistribution of the sound waves during propagation, thus leaving unique pathological features in the acoustic signature signal.

[0031] The sound acquisition unit 6 is mounted on the frame 1 and is used to acquire the acoustic signal generated by the striking excitation mechanism 4. The sound acquisition unit 6 is suspended or fixed on the frame 1. The sound acquisition unit 6 can capture the acoustic signal radiated by the chain plate 201 with high fidelity at the moment of striking. Due to the use of active striking excitation, the initial energy of the acoustic signal is much higher than the surrounding random background noise, thereby significantly improving the signal-to-noise ratio.

[0032] The control and analysis unit 5 is electrically connected to the position detection mechanism 3, the impact excitation mechanism 4, and the sound acquisition unit 6. It controls the impact excitation mechanism 4 based on the position and movement timing detected by the position detection mechanism 3, and monitors for cracks in the chain 2 of the chain conveyor based on acoustic signature signals. On one hand, the control and analysis unit 5 receives the timing signal from the position detection mechanism 3, calculates the optimal impact timing, and issues an action command to the impact excitation mechanism 4 to ensure that each impact falls within the effective detection area of ​​the chain plate 201. On the other hand, it simultaneously receives the acoustic signature signals captured by the sound acquisition unit 6, uses frequency domain transformation and feature extraction algorithms to analyze the energy distribution pattern contained in the acoustic signature signals, and then determines whether there are cracks in the chain plate 201 and the severity of the cracks.

[0033] In some embodiments, the position detection mechanism 3 includes an angle sensor 302 and a deflection rod 303.

[0034] Specifically, the angle sensor 302 is mounted on a fixed bracket 301 above the frame 1, with its axis of rotation perpendicular to the running direction of the chain 2 of the plate chain machine. A deflection rod 303 is mounted on the output end of the angle sensor 302, with one end of the deflection rod 303 extending into the gap between the pins 202 of the plate chain machine 2. The deflection rod 303 can be a metal rod with a length of 80 mm to 120 mm. This length range ensures that the free end of the deflection rod 303 accurately probes the gap between adjacent pins 202, while avoiding unnecessary friction with the chain plate 201 body.

[0035] When the chain 2 of the plate chain conveyor moves, the deflector rod 303, driven by the pin 202, deflects around its mounting point (i.e., the connection point with the angle sensor 302) as its rotation center. The angle sensor 302 detects the deflection angle. In actual operation, as the plate chain 2 moves continuously under the drive sprocket, the pin 202 on the chain 2 passes under the deflector rod 303 sequentially. Because the free end of the deflector rod 303 extends into the movement path of the pin 202, the moving pin 202 inevitably contacts the deflector rod 303 and applies a horizontal thrust to it. Under the continuous push of the pin 202, the deflector rod 303 is forced to deflect. The angle sensor 302, rotating synchronously with the deflector rod 303, can detect this change in deflection angle in real time and at high frequency, and convert it into an electrical signal output.

[0036] When the deflecting rod 303 deflects to a preset angle, it disengages from the pin 202 and resets under gravity. As the chain 2 of the plate chain machine continues to move forward, the deflection angle of the deflecting rod 303 pushed by the pin 202 gradually increases. When the deflecting rod 303 deflects to a preset angle (which is usually determined by the height of the pin 202, the length of the deflecting rod 303, and the relative spatial geometric relationship between the two), the free end of the deflecting rod 303 will slide past the top of the pin 202, thus disengaging from the thrust constraint of the pin 202. After disengaging, the deflecting rod 303, under its own gravity, quickly swings downward and returns to its initial natural drooping state, awaiting the arrival of the next pin 202.

[0037] The electrical signal output by the angle sensor 302 exhibits a highly regular periodic pulse characteristic, with each pulse peak or trough corresponding to the passage of a link of the chain plate 201. The position detection mechanism 3 calculates the running speed of the chain 2 based on this pulse signal, establishes a chain link encoding record in conjunction with the chain plate 201 pitch, and triggers the striking excitation mechanism 4 to execute the striking action when the target chain plate 201 moves to the center area of ​​the striking head.

[0038] In harsh environments filled with high-temperature steam and dense dust, such as solid-state fermentation of baijiu (Chinese liquor), traditional optical lenses are easily blocked by dust, leading to signal loss. Electromagnetic induction is also easily interfered with by complex metal structures, resulting in false triggering. This embodiment uses a gravity-reset mechanical deflection structure to achieve positioning of the single-section chain plate 201 and its movement sequence. Regardless of fluctuations in the running speed of the chain 2 of the plate chain machine, even when the chain 2 experiences slight up-and-down jumping or reverse rotation, the deflection rod 303 can always maintain reliable interaction with the pin 202 by gravity.

[0039] See Figure 2 In some embodiments, the striking mechanism 4 includes a reciprocating drive assembly 41 and a striking head 42.

[0040] Specifically, the reciprocating drive assembly 41 is used to reciprocate in a direction perpendicular to the surface of the chain plate 201. The striking head 42 is installed at the output end of the reciprocating drive assembly 41 and is used to apply a force parallel to the axial direction of the pin 202 to the chain plate 201.

[0041] The reciprocating drive assembly 41 adopts a reciprocating electromagnet structure, specifically including: Casing 411; The first coil 412 is fixedly installed inside the housing 411; The second coil 413 is arranged on the same axis as the first coil 412 and is fixed to the housing 411. A central hole is provided in the center of the second coil 413 along the axis. The movable part 414 is disposed between the first coil 412 and the second coil 413, and can reciprocate along the axial direction of the first coil 412 as the first coil 412 and the second coil 413 are switched on and off. The movable part 414 is slidably connected to the inner cavity of the housing 411, and a connecting rod is provided on the movable part 414. The end of the connecting rod away from the movable part 414 passes through the central hole and is connected to the striking head 42.

[0042] The first coil 412 and the second coil 413 are arranged coaxially and symmetrically inside the cylindrical housing 411, forming a dual-coil drive structure. The movable component 414 passes through the central hole of the second coil 413 and can slide freely back and forth in the axial direction. The movable component 414 is usually made of a soft magnetic material with high magnetic permeability, which can respond sensitively to changes in the surrounding magnetic field.

[0043] In terms of working principle, when the control analysis unit 5 determines that the target chain plate 201 has reached the designated striking position, it sends a current pulse to the second coil 413. The second coil 413 generates electromagnetic force, driving the movable part 414 to extend, carrying the striking head, to strike the chain plate 201. After the striking action is completed, the control circuit cuts off the current to the second coil 413 and simultaneously sends a reverse current to the first coil 412. The first coil 412 generates an upward electromagnetic attraction, pulling the movable part 414 and the striking head upwards, resetting them to their initial standby state.

[0044] The key to overcoming the fatigue failure and slow response defects of traditional spring return mechanisms lies in setting up the reciprocating drive component 41. In practical industrial applications, the running speed of the chain 2 of the plate chain machine is often relatively high, which requires the striking excitation mechanism 4 to have extremely high response frequency and action accuracy. In the traditional single-coil plus return spring structure, when faced with high-frequency reciprocating motion, the return spring is very prone to fatigue yielding or even fracture failure due to alternating stress, and the return speed is limited by the inherent elastic coefficient, resulting in a serious response lag.

[0045] By precisely adjusting the amplitude of the driving current supplied to the dual coils (e.g., 5 amps to 20 amps) or the pulse duty cycle (e.g., 20% to 80%), the striking force of the striking head can be controlled, ensuring that a sufficiently strong acoustic signal is generated while minimizing damage to the surface of the chain plate 201.

[0046] In some embodiments, in order to solve the problem of signal decoupling difficulties caused by the superposition of stress changes and crack characteristics when the chain 2 is under load, and to improve the signal-to-noise ratio and stability of the acoustic signal, the striking excitation mechanism 4 is set in the return section of the chain 2 of the plate chain machine, and is located above or on the side of the chain 2.

[0047] Specifically, the striking excitation mechanism 4 is arranged above or to the side of the return section of the plate chain conveyor chain 2, with the striking position selected in the slack section or low-tension area of ​​the chain 2. In material conveying processes such as solid-state fermentation of baijiu, the working cycle of the plate chain conveyor chain 2 is usually divided into a heavy-load working section carrying materials and an empty return section. In the heavy-load working section, the chain 2 not only needs to withstand the huge weight of the materials, but also needs to overcome the extremely high tensile tension generated by the sprocket drag. If acoustic striking tests are carried out in this area, the metal lattice inside the chain plate 201 will be in a highly tensile state under the action of huge alternating tensile and compressive stress. This complex background stress field will seriously change the propagation speed and attenuation characteristics of sound waves inside the metal, causing the weak high-frequency scattered signals generated by cracks to intertwine and deeply superimpose with the low-frequency structural noise generated by the deformation of the chain 2, making it extremely difficult to successfully decouple and separate the crack characteristic signals.

[0048] The striking excitation mechanism 4 is positioned in the return section. When the chain 2 of the plate chain conveyor passes the tail sprocket and enters the return section, the material on the chain 2 has been completely unloaded, and the chain 2 in this section is usually in a natural slack state or a region of extremely low tension. At this time, the residual stress inside the chain plate 201 is completely released, and the metal material returns to its natural acoustic isotropic state. In this unloaded environment, the striking excitation mechanism applies mechanical striking to the chain plate 201 from above or the side of the chain 2, and the excited sound waves can propagate freely and uniformly inside the chain plate 201. Once the sound waves encounter hidden fatigue cracks, the crack tip and the closing surface will produce pure and clear high-frequency scattering and nonlinear harmonic responses. Due to the elimination of the interference of load stress, the acoustic characteristics obtained in the return section exhibit extremely high stability and consistency, and the signal-to-noise ratio of the crack characteristic signal is significantly improved.

[0049] In addition, placing the striking mechanism above or to the side not only effectively avoids the accumulation area of ​​material debris and dust that may remain at the bottom of the chain 2, ensuring clean contact between the striking head and the surface of the chain plate 201, but also leaves a wide and unobstructed acoustic field of view for the arrangement of the sound acquisition unit 6, thus laying the foundation for the subsequent crack state discrimination by the control and analysis unit 5.

[0050] In some embodiments, in order to solve the problem that single-point sound pickup is easily affected by on-site mechanical solid sound transmission and airflow dust interference, and to achieve spatial filtering and sound source directional enhancement, the sound acquisition unit 6 includes a microphone array, which includes multiple microphones.

[0051] Specifically, the microphone array consists of 3 to 4 directional condenser microphones arranged in a triangular or arc shape. In the actual industrial environment of a chain conveyor, the acoustic environment is extremely harsh and complex. In addition to the effective acoustic signal generated by the active striking of the chain plate 201 by the striking excitation mechanism, the space is also filled with the low-frequency roar of the motor, the metallic friction sound of the sprocket and chain 2 meshing, and the broadband wind noise generated by the airflow in the workshop. If a traditional single-point microphone pickup scheme is used, the microphone can only passively receive all the sound wave mixtures reaching its diaphragm, completely losing the ability to distinguish the spatial location of the sound source. The strong background noise from all directions will easily drown out the weak crack characteristic signal generated by the striking.

[0052] A microphone array containing multiple microphones is introduced. By spatially arranging these microphones according to a specific geometric topology (e.g., an equilateral triangle, a cross, or an arc with a specific curvature), the sound acquisition unit 6 is endowed with powerful spatial filtering and sound source directionality. When the striking excitation mechanism strikes the chain plate 201 to emit sound waves, due to the slight geometric differences in the spatial positions of each microphone, the time (i.e., phase) and sound pressure level (i.e., amplitude) of the sound waves arriving at the diaphragms of different microphones will produce slight but definite differences. The control and analysis unit 5, by synchronously acquiring the raw audio data from these multiple microphones and using beamforming algorithms or blind source separation technology, can perform precise delay summation and coherent processing on these signals with phase differences.

[0053] This array-based processing artificially constructs a high-gain acoustic main lobe pointing towards the impact point at the algorithmic level, resulting in a significant in-phase superposition enhancement of the effective acoustic signal from the impact point direction. Simultaneously, interference noise from other non-target directions (such as the motor or sprocket direction) is suppressed through phase misalignment, achieving deep destructive interference. Therefore, the introduction of the microphone array significantly improves the signal-to-noise ratio of the target acoustic signal at the acquisition end, enabling the online monitoring device to accurately capture the micro-crack features of the chain plate 201 in a noisy industrial workshop.

[0054] For example, in order to effectively capture direct sound and suppress side ambient noise, and maximize the acquisition of the original high-frequency characteristics of the impact excitation, the sound acquisition unit 6 is arranged within a range of 30 cm to 100 cm around the impact point of the impact excitation mechanism, and at least one microphone is aligned with the impact point.

[0055] Specifically, the microphone array is positioned within a 30-100 cm radius of the impact point. The main pickup direction of the microphone is aligned with the impact position, and the pickup angle is controlled between 60 and 90 degrees. In the field of acoustic non-destructive testing, when the impact head 42 strikes the chain plate 201, the excited sound waves radiate outward in the form of spherical waves. The sound waves that propagate directly from the impact point to the microphone diaphragm are called direct sound, which contains original, rich, and unreflected high-frequency scattering characteristics of the crack; while the sound waves that reach the microphone after being reflected by the rack 1, the ground, or a wall are called reverberant sound or reflected sound. These reflected sounds have severely attenuated energy, and their phase and spectral structure have been distorted, which interferes with feature extraction.

[0056] By locking the distance between 30 and 100 centimeters—the acoustic sweet spot—a balance is struck between signal strength and near-field interference. If the device is placed too far away (e.g., more than 100 centimeters), the energy of the direct sound will drop sharply, easily falling below the microphone's noise floor, while the reverberation ratio will increase significantly. If the device is placed too close (e.g., less than 30 centimeters), it is highly susceptible to interference from near-field airflow (i.e., wind noise) generated by the mechanical movement of the striking mechanism itself, and may even face the risk of being damaged by flying materials.

[0057] Meanwhile, the microphone's main pickup direction (usually a cardioid or supercardioid microphone) is locked onto the tapping point. This directional pickup posture can acquire effective acoustic signature characteristics from the tapping point with high sensitivity, while exhibiting a repulsive and attenuating effect on ambient background noise and multipath reflections from the sides and back. In addition, the microphone is mounted on a shock-absorbing frame, which is connected to the frame 1 by rubber pads or springs to isolate the transmission of mechanical vibrations.

[0058] In some embodiments, in order to ensure effective transmission of striking energy and make the fundamental frequency generated by the striking excitation fall within a specific range, so as to facilitate the extraction of the characteristic frequency band of the crack, the striking head 42 is made of an alloy material that matches the acoustic impedance of the chain plate 201.

[0059] Specifically, the striking head is made of high-carbon alloy steel, and its acoustic impedance is matched with that of the 201 steel chain plate to ensure effective energy transfer during striking. In active excitation acoustic non-destructive testing technology, the energy transfer efficiency between the excitation source and the object under test is the fundamental physical basis determining the quality of the final acoustic signal. Acoustic impedance is the product of the medium density and the speed of sound propagation in that medium; it determines the reflection and transmission behavior of sound waves at the interface between two different media.

[0060] If materials with severely mismatched acoustic impedance are used (e.g., striking a high-strength steel chain plate 201 with a rubber head or a low-density aluminum alloy head), most of the striking kinetic energy will be strongly reflected at the contact interface, converted into the rebound kinetic energy of the striking head 42 itself and useless noise in the air. The effective acoustic energy that can actually penetrate into the interior of the chain plate 201 and excite structural resonance and crack scattering is negligible, resulting in extremely unstable fundamental frequency of the collected acoustic signal and a chaotic spectral structure.

[0061] This impedance-matched hard impact generates a clear, steep impact pulse, ensuring that the acoustic fundamental frequency generated by the impact excitation stably falls within the ideal low-frequency range of 200 Hz to 800 Hz. This stable fundamental frequency acts as a solid acoustic anchor, providing an absolutely reliable frequency reference for subsequent algorithms to accurately search for and extract the weak high-frequency scattered energy generated by the friction at the crack edge in the high-frequency range of 2 to 5 octaves of the fundamental frequency (i.e., 1200 Hz to 3000 Hz), greatly improving the scientific rigor and accuracy of crack detection.

[0062] In some embodiments, in order to address the problem of how to achieve graded early warning and linkage control based on crack classification results and form a safety closed loop from monitoring to execution, the plate chain machine chain crack online monitoring device also includes an alarm module, which is used to issue an alarm signal when the control analysis unit 5 determines that the chain 2 has cracked.

[0063] Specifically, the alarm module is electrically connected to the control and analysis unit 5. The alarm module triggers corresponding actions based on the crack classification results.

[0064] For example, an alarm module may include a buzzer, a display screen, etc. Specifically, alarms can be triggered through voice, buzzer sounds, indicator lights, text alerts, etc.

[0065] In addition, this application also includes an environmental noise reduction module. This module is used to collect background noise samples when the chain conveyor is operating normally but without any striking action, and to establish a noise spectrum template. During the detection process, the real-time acquired acoustic signature signal is compared with the noise template using adaptive filtering or spectral subtraction to eliminate or reduce background noise interference from the acoustic signature signal generated by striking excitation, further improving the signal-to-noise ratio of crack features. The addition of this auxiliary module enables the monitoring device to maintain excellent feature extraction capabilities even in extremely noisy industrial environments.

[0066] Based on the hardware architecture of the above-mentioned online monitoring device for cracks in the chain of a plate chain machine, this application embodiment also provides an online monitoring method for cracks in the chain 2 of a plate chain machine. This method aims to solve the problem of how to accurately extract crack features and automatically classify crack levels, achieving intelligent and quantitative diagnosis from the original sound signature to the crack state.

[0067] The method includes: transforming the acoustic signal to extract the energy distribution of characteristic frequency bands, thereby determining the energy amplitude, spectral sharpness, and energy ratio of the high-frequency band of crack scattering to the fundamental frequency band. The energy amplitude, spectral sharpness, and energy ratio of the high-frequency band of crack scattering to the fundamental frequency band are compared with standard crack parameters to determine the chain 2 crack data, which includes no crack, micro-crack, obvious crack, and severe crack.

[0068] In the field of industrial acoustic nondestructive testing, the acoustic response of the chain 2 of a plate chain conveyor when subjected to impact is an extremely complex nonlinear dynamic process. Normal vibration of the chain plate 201 is mainly concentrated in the low-frequency fundamental band. While microscopic friction and collision at the crack interface generate high-frequency scattering, the energy of these high-frequency signals is extremely weak and easily confused with the high-frequency mechanical friction noise in the field. Traditional time-domain analysis methods (such as calculating peak value and RMS value) are difficult to identify such weak high-frequency distortions; while simple frequency-domain thresholding methods are prone to serious misjudgments due to minute fluctuations in impact force. This application introduces a machine learning classification model to achieve accurate diagnosis of crack conditions.

[0069] The specific implementation steps are as follows: Step S11, microphone array acquisition step. The original acoustic signal generated by the striking excitation mechanism striking the chain plate 201 is captured by the sound acquisition unit 6 (microphone array).

[0070] Step S12, bandpass filtering step.

[0071] The signal processing module in the control and analysis unit 5 first performs bandpass filtering on the original acoustic signal, retaining the 50 Hz to 50 kHz frequency band signal and filtering out low-frequency rack 1 vibration below 50 Hz and ultra-high frequency electromagnetic interference above 50 kHz.

[0072] Step S13, Fast Fourier Transform (FFT) step.

[0073] A fast Fourier transform is performed on the filtered acoustic signal to map the one-dimensional time-domain sound pressure signal to a two-dimensional frequency domain space, obtaining a clear spectral distribution map that reveals the energy distribution of the signal at each frequency point.

[0074] Step S14, crack feature extraction and judgment step.

[0075] Based on the material properties of the striking head, the low-frequency range of 200 Hz to 800 Hz was identified as the fundamental frequency band, and the 2nd to 5th octave band (i.e., 1200 Hz to 3000 Hz) was identified as the high-frequency band for crack scattering. The relative ratio of the total energy in the high-frequency band to the total energy in the fundamental frequency band (denoted as the energy ratio R) was calculated. Simultaneously, calculus was performed on the envelope shape of the high-frequency spectrum to extract the spectral sharpness factor (denoted as S), which characterizes the steepness of the spectral peaks, as well as the energy amplitude of the high-frequency band for crack scattering.

[0076] Determining the energy ratio R solves the problem of diagnostic failure caused by absolute energy fluctuations. If the traditional absolute energy threshold method is used, the absolute energy of the voiceprint signal will drop overall if the impact force decreases or the microphone's pickup sensitivity decreases, leading to missed detections. However, the relative ratio of high-frequency scattered energy to low-frequency fundamental energy is determined by the crack size, and this ratio has extremely strong anti-interference robustness regardless of changes in impact force. Simultaneously, determining the spectral sharpness eliminates interference from broadband white noise (such as airflow noise) in the field, because genuine crack friction produces narrowband high-frequency signals with specific harmonic peaks, whose sharpness is far higher than that of smooth white noise.

[0077] After acquiring the three core features—energy amplitude, energy ratio R, and spectral sharpness S—these are used as feature vectors and input into the built-in crack classification model. This model is a multi-classification model trained using massive amounts of historical real-world sample data (standard crack parameters) of known crack states, based on machine learning algorithms such as Support Vector Machine (SVM). The model outputs the classification result through rigorous mathematical comparison.

[0078] Step S15, No Crack Output Step.

[0079] When the model determines that the feature vector meets the parameter range of no crack (e.g., R<1.5 and S<2.0), it outputs a diagnosis result of no crack.

[0080] Step S16, the crack output step.

[0081] When the model determines that the feature vector falls into the parameter range with cracks, it is further subdivided into micro-cracks (e.g., 1.5≤R<3.0 and 2.0≤S<3.5), obvious cracks (e.g., 3.0≤R<5.0 and 3.5≤S<5.0), and severe cracks (e.g., R≥5.0 or S≥5.0).

[0082] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. An online monitoring device for chain cracks in a plate chain conveyor, characterized in that, include: The rack is straddled on the chain to be monitored; A position detection mechanism, mounted on the frame, is used to detect the position and movement sequence of individual chain links on the chain; A striking excitation mechanism is mounted on the frame and is used to apply mechanical striking excitation to the chain plates of the chain. A sound acquisition unit, mounted on the frame, is used to acquire acoustic signals generated by the striking excitation mechanism; The control and analysis unit is electrically connected to the position detection mechanism, the striking excitation mechanism, and the sound acquisition unit, respectively. It is used to control the action of the striking excitation mechanism according to the position and movement sequence detected by the position detection mechanism, and to monitor the chain cracks according to the soundprint signal.

2. The online monitoring device for chain cracks in a plate chain conveyor according to claim 1, characterized in that, Location detection agencies include: An angle sensor, which is mounted on the frame; A deflection rod is installed at the output end of the angle sensor, with one end of the deflection rod away from the angle sensor extending into the pins of the chain; When the chain moves, the deflecting rod is pushed by the pin and deflects around the mounting point of the angle sensor as the center of rotation. The angle sensor detects the deflection angle. When the deflecting rod deflects to a preset angle, the deflecting rod disengages from the pin and resets under the action of gravity.

3. The online monitoring device for chain cracks in a plate chain conveyor according to claim 2, characterized in that, The striking excitation mechanism includes a reciprocating drive assembly and a striking head. The reciprocating drive assembly is used to reciprocate in a direction perpendicular to the surface of the chain plate. The striking head is installed at the output end of the reciprocating drive assembly and is used to apply a force parallel to the axial direction of the pin to the chain plate.

4. The online monitoring device for chain cracks in a plate chain conveyor according to claim 3, characterized in that, The reciprocating drive component includes: case, The first coil is fixedly installed inside the housing; The second coil is arranged on the same axis as the first coil and is fixed to the housing. A central hole is opened at the center of the second coil along the axis. A movable component is disposed between the first coil and the second coil, and can reciprocate axially with the first coil as the first coil and the second coil are energized and de-energized. One end of the movable component passes through the central hole and is connected to the striking head.

5. The online monitoring device for chain cracks in a plate chain conveyor according to claim 1, characterized in that, The striking excitation mechanism is located on the return section of the chain, above or to the side of the chain.

6. The online monitoring device for chain cracks in a plate chain conveyor according to claim 1, characterized in that, The sound acquisition unit includes a microphone array, which contains multiple microphones.

7. The online monitoring device for chain cracks in a plate chain conveyor according to claim 6, characterized in that, The sound acquisition unit is arranged within a range of 30-100cm around the striking point of the striking excitation mechanism, and at least one microphone is pointed at the striking point.

8. The online monitoring device for chain cracks in a plate chain conveyor according to claim 3, characterized in that, The striking head is made of an alloy material whose acoustic impedance is matched to that of the chain plate material.

9. The online monitoring device for chain cracks in a plate chain machine according to any one of claims 1 to 8, characterized in that, The online monitoring device for chain cracks in the plate chain machine also includes an alarm module, which is used to issue an alarm signal when the control and analysis unit determines that cracks have occurred in the chain.

10. A method for online monitoring of chain cracks in a plate chain conveyor, characterized in that, The method, applied to the online monitoring device for chain cracks in plate chain machines as described in any one of claims 1 to 9, comprises: The acoustic signature signal is transformed and processed to extract the energy distribution of the characteristic frequency bands in order to determine the energy amplitude, spectral sharpness, and energy ratio of the high-frequency band of crack scattering to the fundamental frequency band. The energy amplitude, spectral sharpness, and energy ratio of the high-frequency band of crack scattering are compared with the standard parameters of the crack to determine the chain crack data. The chain crack data includes no crack, micro-crack, obvious crack, and severe crack.

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