Gear vibration testing method and device for two-stage transmission press

Abstract

The invention provides a gear vibration testing method and device of a two-stage transmission press machine, and belongs to the technical field of press machine vibration testing and state monitoring, and the method comprises the steps: arranging an acceleration sensor and a cam sensor; collecting a vibration signal and an angle signal under each working condition; preprocessing the vibration signal and performing angular domain resampling to output an angular domain stationary signal; performing time domain and frequency domain analysis on the angular domain stationary signal, and outputting a time domain characteristic index, a meshing frequency and a frequency domain characteristic parameter; performing band-pass filtering on the angular domain stationary signal to extract a high-frequency signal, and calculating an envelope spectrum output envelope characteristic parameter; analyzing sideband characteristics on two sides of the meshing frequency, obtaining a time-varying rule of the meshing characteristics, and outputting sideband and time frequency characteristic parameters; and carrying out gear engagement health evaluation based on the characteristic parameters, and calculating a comprehensive health index so as to carry out quantitative evaluation on the gear engagement state. According to the invention, non-intrusive monitoring is realized, gear faults are accurately diagnosed, and the operation reliability of equipment is improved.

Description

Technical Field

[0001] This application belongs to the field of vibration testing and condition monitoring technology for presses, specifically relating to a gear vibration testing method and device for a two-stage transmission press. Background Technology

[0002] As a core mechanical device for metal forming, the transmission system of a mechanical press typically consists of multi-stage gears, cranks, and connecting rods. The stability of the gear meshing directly affects the transmission accuracy, motion smoothness, and stamping quality of the entire machine. Because the press is subjected to periodic impact loads during operation, the gear pairs are prone to problems such as fluctuations in meshing stiffness, tooth surface wear, and assembly deviations, leading to meshing vibration and abnormal noise, and even gear fatigue failure.

[0003] Traditional gear inspection methods often rely on static precision measurements or subjective assessments of operating noise, making it difficult to accurately identify the formation of meshing anomalies and early faults. While existing vibration testing methods can acquire acceleration or velocity signals, under complex operating conditions such as high-impact, high-background-noise presses, the measured signals have complex components and low signal-to-noise ratios, often obscuring effective fault characteristic information. Furthermore, existing methods are mostly limited to macroscopic analysis of the overall spectrum, lacking in-depth analysis of specific frequency components generated during gear meshing (such as meshing frequency, sidebands, and resonance bands). This results in insensitivity to potential faults such as early tooth surface damage and changes in meshing stiffness, making it difficult to achieve accurate condition assessment and early warning.

[0004] Therefore, there is an urgent need for a high signal-to-noise ratio vibration testing method that can effectively extract and analyze the dynamic characteristics of gear meshing under press operating conditions, so as to achieve real-time and quantitative evaluation of gear meshing status and early fault identification. Summary of the Invention

[0005] In a first aspect, embodiments of this application provide a method for testing gear vibration in a two-stage transmission press. The two-stage transmission press includes a flywheel, a high-speed gearbox connected to the flywheel, a low-speed gearbox connected to the output shaft of the high-speed gearbox, a crank-slider mechanism driven by a crankshaft output from the low-speed gearbox, and a balancer cylinder for balancing the weight of the slider in the crank-slider mechanism. A cam sensor for detecting the rotational angle position of the crankshaft is provided on the crankshaft. The method includes the following steps: S1. Several sets of triaxial acceleration sensors are arranged on the outer walls of the high-speed gearbox and the low-speed gearbox, and the cam sensor signal is brought out at the same time to realize the synchronous acquisition of vibration signal and crankshaft angle signal. S2. Under the operation of the secondary press, set up different combinations of balancer air pressure and different slider speeds, and collect vibration signals and crankshaft angle signals under each working condition in a multi-channel synchronous manner. S3. Perform anti-aliasing filtering, detrending and bandpass filtering on the acquired vibration signal, and use the crankshaft angle signal for angular domain resampling to output a stable angular domain signal; S4. Perform time-domain and frequency-domain analysis on the stationary signal in the angle domain, and output the time-domain characteristic index, gear pair meshing frequency and frequency-domain characteristic parameters; S5. Bandpass filtering is performed on the stationary signal in the angular domain to extract the high-frequency signal. Then, Hilbert transform is performed on the high-frequency signal for envelope demodulation to extract the gear meshing impact envelope signal and calculate the envelope spectrum output envelope characteristic parameters. S6. Analyze the sideband characteristics on both sides of the meshing frequency of the gear pair, and use time-frequency analysis to obtain the law of gear meshing characteristics changing with time, and output the sideband and time-frequency characteristic parameters; S7. Based on time-domain characteristic indicators, frequency-domain characteristic parameters, envelope characteristic parameters, sideband and time-frequency characteristic parameters, gear meshing health is evaluated, and the comprehensive health index HI is calculated to quantitatively assess the gear meshing state.

[0006] Furthermore, the specific steps of step S1 are as follows: S11. A set of three-dimensional acceleration sensors is arranged on the front left, rear left, front right, and rear right covers of the low-speed gearbox, and the sensitive axis of each set of three-dimensional acceleration sensors is perpendicular to the mounting surface. S12. A set of three-dimensional acceleration sensors is arranged directly above the intermediate shaft bearing cover of the high-speed gearbox; S13. Connect the pulse signal from the cam sensor to the rotation speed channel of the signal acquisition system via a shielded wire, and connect each triaxial acceleration sensor to the vibration channel of the signal acquisition system.

[0007] Furthermore, the specific steps of step S2 are as follows: S21. Set the balancer's air pressure to three operating conditions: standard air pressure, low air pressure, and high air pressure. S22. Set at least three different slider operating speeds for each wind pressure condition; S23. Under each combination of wind pressure and speed, the vibration signals of all three-dimensional acceleration sensors and the crankshaft angle signal of the cam sensor are collected synchronously at a preset sampling frequency, and the continuous collection time meets the time length threshold.

[0008] Furthermore, the specific steps of step S3 are as follows: S31. The original vibration signal is sequentially subjected to anti-aliasing filtering and linear detrending term processing according to the preset cutoff frequency signal; S32. Set a bandpass filter for filtering based on the estimated gear meshing frequency range; S33. Based on the acquired crankshaft angle signal, the filtered time-domain vibration signal is resampled into a stationary angular domain signal with equal angular intervals using cubic spline interpolation. Specifically, for time series and corresponding vibration signals The interval formed, the cubic polynomial constructed and the second derivative of a cubic polynomial The following system of equations is satisfied:

[0009]

[0010]

[0011]

[0012]

[0013] in, In order to keep pace with time The corresponding crankshaft angular coordinates, , , and They are cubic, quadratic, linear, and constant terms, respectively, along with time. The corresponding coefficients; Set target interpolation point (k=1,2,...,N) represents N uniform angle points per revolution. The interpolated angular domain stationary signal is obtained by solving the system of equations. .

[0014] Furthermore, the specific steps of step S4 are as follows: S41. Calculate the stationary signal in the angular domain peak Root mean square value Peak factor and kurtosis As a time-domain characteristic indicator;

[0015]

[0016] Where μ is the angular-domain stationary signal The mean of σ is the stationary signal in the angular domain. The standard deviation of N, where N is the number of sampling points. Let n be the vibration signal amplitude corresponding to the nth angular sampling point, where n is the sampling point number of the stationary signal in the angular domain, n=1,2,3,...,N; S42. Diagonal stationary signal Perform a Fast Fourier Transform to obtain the spectrum, and identify and extract the meshing frequency of the gear pair from the spectrum. :

[0017] in, This refers to the number of teeth on the gear. The crankshaft rotational frequency; S43. Calculate frequency domain characteristic parameters: frequency doubling amplitude ratio ; Energy Concentration

[0018] Where: A1 is the fundamental meshing frequency of the gear pair in the spectrum. The amplitude, A2 is the second harmonic of the meshing frequency in the spectrum. The amplitude, A3 is the third harmonic of the meshing frequency in the spectrum. The amplitude, A4 is the fourth harmonic of the meshing frequency in the spectrum. The amplitude.

[0019] Furthermore, the specific steps of step S5 are as follows: S51. Construct a bandpass filter with the target center frequency and bandwidth, and use the constructed bandpass filter to extract a stationary signal from the angular domain. Extracting high-frequency resonance signals from them; S52. For high-frequency resonance signals The envelope signal is obtained by envelope demodulation using Hilbert transform. The specific steps are as follows: For high-frequency resonance signals Perform Hilbert transform to obtain the high-frequency resonant signal. orthogonal components The transformation formula is:

[0020] Where PV represents the Cauchy principal value integral; High-frequency resonance signal Orthogonal components of the Hilbert transform Combining to construct analytic signals :

[0021] Where j is the imaginary unit; Calculate analytic signals The modulus is the envelope signal. :

[0022] S53. Perform a Fast Fourier Transform on the envelope signal to obtain the envelope spectrum, and calculate the envelope impact factor. : .

[0023] Furthermore, the specific steps of step S6 are as follows: S61. Identify the meshing frequency of the gear pair from the frequency spectrum. The distance between the two sides is the crankshaft rotational frequency. The border tribe; S62. Based on the amplitude information of the spectrum, calculate the ratio of the total energy of the first three sidebands in the sideband family to the energy of the main frequency, and use this ratio as the sideband energy ratio. :

[0024] Where k is the order of the sideband, and k = 1, 2, 3 is taken, that is, the first three orders of sidebands are summed; The frequency is equal to the meshing frequency. Add k times the crankshaft frequency The sideband amplitude, The frequency is equal to the meshing frequency. Subtract k times the frequency The sideband amplitude; Meshing frequency The amplitude; S63. Short-time Fourier transform is used to analyze stationary signals in the angular domain. By selecting a preset window function length and overlap rate, a time-frequency distribution map is generated to identify the maximum value of the impact signal energy occurring within a preset crank angle interval corresponding to the loading stage of the press, which is denoted as the time-frequency impact energy. .

[0025] Furthermore, the specific steps of step S7 are as follows: S71. The root mean square value in the time-domain characteristic index. Peak factor , cliff The ratio of the octave amplitude in the frequency domain characteristic parameters and the envelope impact factor in the envelope characteristic parameters. The parameters are compared with the corresponding parameters under healthy baseline conditions and then normalized. The normalization formula is as follows:

[0026] in, The current parameter value. Baseline parameter values, These are the normalized parameter values; S72. The comprehensive health index HI is calculated through weighted fusion, and its calculation formula is as follows:

[0027] in, This represents the normalized root mean square value. This represents the peak factor after normalization. Indicates the normalized kurtosis. This represents the normalized octave amplitude ratio. This represents the normalized envelope impact factor. , , , , Let be the weight coefficient, and satisfy... ; S73. Based on the comprehensive health index Assess the gear's condition and set a first health index threshold. Second health index threshold Third health index threshold ; in, The status assessment rules are as follows: like If so, the gear meshing state is determined to be normal; like If so, the gear meshing state is determined to be slightly uneven; like If so, the gear meshing condition is determined to be moderate wear; like If so, the gear meshing state is determined to be severely abnormal.

[0028] Furthermore, in step S71, the sideband energy ratio in the sideband characteristic parameters is also... and time-frequency impact energy as a time-frequency characteristic parameter Perform normalization; And the comprehensive health index in step S72 Add corresponding weighting terms to the calculation formula and ,and :

[0029] in, The normalized sideband energy ratio. This is the normalized time-frequency impact energy.

[0030] Secondly, this application also provides a gear vibration testing device for a two-stage transmission press. The two-stage transmission press includes a flywheel, a high-speed gearbox connected to the flywheel, a low-speed gearbox connected to the output shaft of the high-speed gearbox, a crank-slider mechanism driven by a crankshaft output from the low-speed gearbox, and a balancer cylinder for balancing the weight of the slider in the crank-slider mechanism. A cam sensor for detecting the rotational angle position of the crankshaft is provided on the crankshaft; including: The sensor arrangement and synchronization module is used to arrange several sets of triaxial acceleration sensors on the outer walls of the high-speed gearbox and the low-speed gearbox, and at the same time extract the cam sensor signal to realize the synchronous acquisition of vibration signal and crankshaft angle signal. The multi-condition synchronous acquisition module is used to set different combinations of balancer air pressure and different slider speeds in the operation of the secondary press, and to acquire vibration signals and crankshaft angle signals under each condition in a multi-channel synchronous manner. The signal preprocessing module is used to perform anti-aliasing filtering, detrending and bandpass filtering on the acquired vibration signal, and to perform angular domain resampling using the crankshaft angle signal to output a stationary angular domain signal. The time-frequency feature extraction module is used to perform time-domain and frequency-domain analysis on stationary signals in the angular domain, and outputs time-domain feature indices, gear pair meshing frequency, and frequency-domain feature parameters. The envelope demodulation analysis module is used to perform bandpass filtering on the angular domain stationary signal to extract the high-frequency signal, then perform Hilbert transform envelope demodulation on the high-frequency signal to extract the gear meshing impact envelope signal, and calculate the envelope spectrum output envelope feature parameters. The sideband and time-frequency analysis module is used to analyze the sideband characteristics on both sides of the meshing frequency of the gear pair, and to obtain the law of gear meshing characteristics changing with time using time-frequency analysis method, and output sideband and time-frequency characteristic parameters; The health status assessment module is used to evaluate gear meshing health based on time-domain characteristic indicators, frequency-domain characteristic parameters, envelope characteristic parameters, sideband and time-frequency characteristic parameters, and calculate the comprehensive health index HI to quantitatively assess the gear meshing status.

[0031] As can be seen from the above technical solutions, this application has the following advantages: The gear vibration testing method and apparatus for a two-stage transmission press provided in this application comprehensively monitors the gear meshing state and accurately identifies early fault characteristics, such as tooth surface wear and changes in meshing stiffness, through multi-dimensional vibration signal acquisition and analysis. It is applicable to vibration monitoring under different combinations of wind pressure and speed, adapting to the complex operating environment of the press and providing a physical correspondence for dynamic feature identification. This application eliminates the need for equipment disassembly, enabling real-time monitoring during normal press operation, reducing downtime and improving equipment operating efficiency. The use of multi-layer filtering and angular domain resampling strategies eliminates the influence of speed fluctuations and background noise, ensuring the stability and reliability of test results. Through the parameterized index HI (Health Index), complex vibration characteristics are quantified into a single health index, achieving automated monitoring and trend warning, providing a reasonable basis for equipment maintenance. Attached Figure Description

[0032] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic flowchart of the gear vibration testing method for the two-stage transmission press of the present invention.

[0034] Figure 2 This is a schematic diagram of the gear vibration testing device for the two-stage transmission press of the present invention. Detailed Implementation

[0035] The various embodiments of this disclosure will be described more fully in the detailed steps of the gear vibration testing method for a two-stage transmission press described below. This disclosure may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of this disclosure to the specific embodiments disclosed herein, but rather this disclosure should be understood to cover all adjustments, equivalents, and / or alternatives falling within the spirit and scope of the various embodiments of this disclosure.

[0036] This embodiment provides a gear vibration testing method for a two-stage transmission press. Through non-invasive monitoring and multi-dimensional analysis, it can accurately identify early gear failures, adapt to various working conditions, improve equipment operating efficiency and reliability, and reduce maintenance costs.

[0037] The technical solutions of 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.

[0038] Please see Figure 1 The diagram shows a flowchart of a gear vibration testing method for a two-stage transmission press in a specific embodiment. The two-stage transmission press includes a flywheel, a high-speed gearbox connected to the flywheel, a low-speed gearbox connected to the output shaft of the high-speed gearbox, a crank-slider mechanism driven by a crankshaft output from the low-speed gearbox, and a balancer cylinder for balancing the weight of the slider in the crank-slider mechanism. A cam sensor for detecting the rotational angle position of the crankshaft is provided on the crankshaft. The method includes the following steps: S1. Several sets of triaxial acceleration sensors are arranged on the outer walls of the high-speed gearbox and the low-speed gearbox, and the cam sensor signal is brought out at the same time to realize the synchronous acquisition of vibration signal and crankshaft angle signal. It should be noted that by arranging multiple sets of triaxial acceleration sensors on the outer wall of the high-speed and low-speed gearboxes, vibration signals at different locations can be monitored simultaneously, ensuring the comprehensiveness of the data; by introducing cam sensor signals, the vibration signals and crankshaft angle signals can be acquired synchronously, providing dual references of time and angle for analysis. S2. Under the operation of the secondary press, set up different combinations of balancer air pressure and different slider speeds, and collect vibration signals and crankshaft angle signals under each working condition in a multi-channel synchronous manner. It should be noted that by setting various combinations of balancer air pressure and slider speed, the actual operating conditions of the press are fully covered; and the integrity and consistency of the data are ensured by multi-channel synchronous acquisition, providing a data foundation for data analysis. S3. Perform anti-aliasing filtering, detrending and bandpass filtering on the acquired vibration signal, and use the crankshaft angle signal for angular domain resampling to output a stable angular domain signal; It should be noted that anti-aliasing filtering and detrending processing effectively eliminated system noise and baseline drift, improving the signal-to-noise ratio; angular domain resampling eliminated the influence of speed fluctuations on signal analysis, ensuring the accuracy of frequency analysis. S4. Perform time-domain and frequency-domain analysis on the stationary signal in the angle domain, and output the time-domain characteristic index, gear pair meshing frequency and frequency-domain characteristic parameters; It should be noted that time-domain analysis can identify the periodicity and impact characteristics of vibration, providing a basis for judging the fluctuation of gear meshing stiffness; frequency-domain analysis can extract the meshing frequency and its harmonic characteristics, and evaluate the uniformity of gear meshing stiffness by the harmonic amplitude ratio and energy concentration. S5. Bandpass filtering is performed on the stationary signal in the angular domain to extract the high-frequency signal. Then, Hilbert transform is performed on the high-frequency signal for envelope demodulation to extract the gear meshing impact envelope signal and calculate the envelope spectrum output envelope characteristic parameters. It should be noted that extracting the envelope signal through Hilbert transform can amplify weak impact characteristics and effectively identify early tooth surface damage; envelope spectrum analysis can reveal local fault characteristics, such as tooth surface wear or tooth profile errors, thus improving diagnostic sensitivity. S6. Analyze the sideband characteristics on both sides of the meshing frequency of the gear pair, and use time-frequency analysis to obtain the law of gear meshing characteristics changing with time, and output the sideband and time-frequency characteristic parameters; It should be noted that by analyzing the sideband characteristics on both sides of the meshing frequency, the modulation source of the gear transmission system, such as periodic stiffness fluctuations, can be identified; and time-frequency analysis can reveal the changing law of gear meshing characteristics over time, providing a basis for fault location and trend analysis. S7. Based on time-domain characteristic indicators, frequency-domain characteristic parameters, envelope characteristic parameters, sideband and time-frequency characteristic parameters, gear meshing health is evaluated, and the comprehensive health index HI is calculated to quantitatively assess the gear meshing state. It should be noted that a health evaluation model was constructed based on time domain, frequency domain, envelope, sideband, and time-frequency characteristic parameters, achieving the fusion of multi-dimensional features; and a quantitative assessment of gear meshing status was achieved through the comprehensive health index HI, providing a reasonable basis for equipment maintenance and fault early warning.

[0039] This embodiment accurately identifies early gear failures through non-invasive monitoring and multi-dimensional signal analysis, adapts to various complex working conditions, improves equipment operating efficiency and reliability, and reduces maintenance costs. At the same time, it adopts anti-interference design and angular domain resampling to ensure stable and reliable test results, providing a reasonable basis for press health monitoring and fault early warning.

[0040] Furthermore, as a refinement and extension of the specific implementation of the above embodiments, in order to fully illustrate the specific implementation process in this embodiment, another gear vibration testing method for a two-stage transmission press is provided. The two-stage transmission press includes a flywheel, a high-speed gearbox connected to the flywheel, a low-speed gearbox connected to the output shaft of the high-speed gearbox, a crank-slider mechanism driven by a crankshaft output from the low-speed gearbox, and a balancer cylinder for balancing the weight of the slider in the crank-slider mechanism. A cam sensor for detecting the rotational angle position of the crankshaft is provided on the crankshaft. Taking the J31-315 type two-stage transmission mechanical press as the test object, the press mainly consists of a flywheel, a high-speed gearbox (containing two pairs of meshing gears with teeth z1=25 and z2=75 respectively), a low-speed gearbox (containing one pair of meshing gears with teeth z3=30 and z4=90), a crank-slider mechanism, and a balancer cylinder. A CS-120 cam sensor is mounted on the crankshaft for real-time detection of the rotational angle position of the crankshaft. The method includes the following steps: S1. Several sets of triaxial acceleration sensors are arranged on the outer walls of the high-speed gearbox and the low-speed gearbox, and the cam sensor signal is simultaneously extracted to achieve synchronous acquisition of vibration signal and crankshaft angle signal; the specific steps of step S1 are as follows: S11. A set of three-dimensional acceleration sensors is arranged on the front left, rear left, front right, and rear right covers of the low-speed gearbox, and the sensitive axis of each set of three-dimensional acceleration sensors is perpendicular to the mounting surface. S12. A set of three-dimensional acceleration sensors is arranged directly above the intermediate shaft bearing cover of the high-speed gearbox; It should be noted that the triaxial accelerometer is fixed with a magnetic base, threads, or industrial clay, and the wires are protected by binding. S13. Connect the pulse signal of the cam sensor to the speed channel of the signal acquisition system through a shielded wire, and connect each triaxial acceleration sensor to the vibration channel of the signal acquisition system; For example, a PCB 356A16 high-sensitivity triaxial accelerometer (sensitivity 100mV / g, frequency response 0.5Hz~10kHz) is selected and arranged according to the following rules: One set of sensors is arranged on each of the left front end, left rear end, right front end, and right rear end covers of the low-speed gearbox. The sensor sensitive axis is perpendicular to the mounting surface and 50mm from the edge of the end cover. The four sets of sensors are at the same height (1200mm from the ground) and are fixed with M5 threads. A set of sensors is arranged directly above the bearing cover of the intermediate shaft of the high-speed gearbox, and is fixed by magnetic adsorption to ensure a tight fit with the bearing cover. All sensor wires are shielded cables, which are fixed to the gearbox housing with cable ties to avoid contact with moving parts, and the joints are protected with waterproof tape. The pulse signal from the cam sensor is connected to the speed channel of the INV3060S multi-channel dynamic signal acquisition system through a shielded wire, and each triaxial accelerometer is connected to the vibration channel to ensure that the vibration signal and the crankshaft angle signal are acquired synchronously with a time synchronization error of ≤1ms. The INV3060S multi-channel dynamic signal acquisition host (16 channels, sampling frequency expandable to 51.2kHz) is used, along with DASP-V10 data acquisition and analysis software; The sampling frequency is set to 25.6kHz (covering the meshing frequency and structural resonance band within a 10kHz range), with 3200 spectral lines to ensure a frequency resolution ≥8Hz; It adopts a dual mode of manual triggering and threshold triggering. When the peak value of the vibration signal exceeds 60% of the sensor's range, it automatically triggers supplementary sampling to avoid the loss of short-term impact signals. S2. With the secondary press running, set up different combinations of balancer air pressure and different slider speeds, and collect vibration signals and crankshaft angle signals under each condition using a multi-channel synchronous method; the specific steps of step S2 are as follows: S21. Set the balancer's air pressure to three operating conditions: standard air pressure, low air pressure, and high air pressure. S22. Set at least three different slider operating speeds for each wind pressure condition; S23. Under each wind pressure and speed combination condition, the vibration signals of all three-dimensional acceleration sensors and the crankshaft angle signal of the cam sensor are collected synchronously according to the preset sampling frequency, and the continuous collection time meets the time length threshold. It should be noted that the sampling frequency is not lower than 12.8kHz and the sampling time is not less than 60s; For example, based on the actual operating scenario of the press, the following combination of operating conditions is set: Balancer air pressure: Standard air pressure (0.4MPa), Low air pressure (0.2MPa), High air pressure (0.6MPa); Slider speed: 8spm, 10spm, 12spm, 15spm (spm is the number of strokes per minute); Operating condition combinations: a total of 3 types of wind pressure × 4 types of speed = 12 sets of test operating conditions, with each set of operating conditions collected independently; Baseline data acquisition: The press was set to flywheel idling state (no impact load), and three sets of vibration signals were acquired at standard wind pressure and a speed of 10 sppm. Each set of acquisition time was 60 seconds. Time domain indicators (peak value, root mean square value, kurtosis, etc.) and frequency domain characteristics were recorded to establish a healthy baseline database. If the root mean square value (RMS) under the baseline state deviates from the design standard value by ≤±10%, it is judged as a qualified baseline. Adjust the balancer air pressure and slider speed sequentially according to the preset working conditions, and start data acquisition after the equipment runs stably (speed fluctuation ≤ ±5%). Vibration signals and crankshaft angle signals were continuously collected for 60 seconds under each working condition. The signal amplitude was monitored in real time during the collection process to ensure that it did not exceed the sensor range (±50g). Data naming convention: wind pressure-velocity-measuring point number-acquisition time, for example 0.4MPa-10spm-low speed level right front-202411241430, to ensure data traceability; S3. Perform anti-aliasing filtering, detrending, and bandpass filtering on the acquired vibration signal, and resample the crankshaft angle signal in the angular domain to output a stationary angular domain signal; the specific steps of step S3 are as follows: S31. The original vibration signal is sequentially subjected to anti-aliasing filtering and linear detrending term processing according to the preset cutoff frequency signal; For example, the cutoff frequency is 1 / 2.56 of the sampling frequency; S32. Set a bandpass filter for filtering based on the estimated gear meshing frequency range; For example, bandpass filtering can be performed by setting the passband frequency range to 0.5 to 3.5 times the estimated meshing frequency. S33. Based on the acquired crankshaft angle signal, the filtered time-domain vibration signal is resampled into a stationary angular domain signal with equal angular intervals using cubic spline interpolation. Specifically, for time series and corresponding vibration signals The interval formed, the cubic polynomial constructed and the second derivative of a cubic polynomial The following system of equations is satisfied:

[0041]

[0042]

[0043]

[0044]

[0045] in, In order to keep pace with time The corresponding crankshaft angular coordinates, , , and They are cubic, quadratic, linear, and constant terms, respectively, along with time. The corresponding coefficients; Set target interpolation point (k=1,2,...,N) represents N uniform angle points per revolution. The interpolated angular domain stationary signal is obtained by solving the system of equations. ; For example, if N is 1024, the time period of each revolution is determined based on the pulse signal of the cam sensor, and each revolution is divided into 1024 angular intervals. The original time-domain vibration signal sequence is resampled into an angular domain signal sequence with 1024 data points per revolution using an interpolation algorithm. For example, the DASP-V10 software is used to preprocess the acquired raw signal, and the steps are as follows: Anti-aliasing filtering: Set the cutoff frequency to 10kHz (1 / 2.56 of the sampling frequency) and use a finite impulse response (FIR) filter to eliminate high-frequency aliasing interference; Detrending processing: A linear detrending algorithm is used to remove low-frequency drift and DC components from the signal, so that the baseline remains stable; Bandpass filtering: Based on the estimated range of gear meshing frequencies (high-speed stage meshing frequency f1=z1×n1 / 60=25×1500 / 60=625Hz, low-speed stage meshing frequency f2=z3×n2 / 60=30×500 / 60=250Hz), the passband frequency is set to 100Hz~2000Hz to filter out low-frequency background vibrations and high-frequency noise; Angular domain resampling: Based on the angle signal from the cam sensor, cubic spline interpolation is used to resample the time-domain signal into a stationary angular domain signal with equal angular intervals. The number of sampling points per revolution is set to N=1024. A cubic polynomial is constructed to satisfy the interpolation conditions. The angular domain signal is obtained by solving the system of equations, eliminating the influence of speed fluctuations on meshing frequency identification. S4. Perform time-domain and frequency-domain analysis on the stationary signal in the angle domain, and output the time-domain characteristic indicators, gear pair meshing frequency, and frequency-domain characteristic parameters; the specific steps of step S4 are as follows: S41. Calculate the stationary signal in the angular domain peak Root mean square value Peak factor and kurtosis As a time-domain characteristic indicator;

[0046]

[0047] Where μ is the angular-domain stationary signal The mean of σ is the stationary signal in the angular domain. The standard deviation of N, where N is the number of sampling points. Let n be the vibration signal amplitude corresponding to the nth angular sampling point, where n is the sampling point number of the stationary signal in the angular domain, n=1,2,3,...,N; S42. Diagonal stationary signal Perform a Fast Fourier Transform to obtain the spectrum, and identify and extract the meshing frequency of the gear pair from the spectrum. :

[0048] in, This refers to the number of teeth on the gear. The crankshaft rotational frequency; S43. Calculate frequency domain characteristic parameters: frequency doubling amplitude ratio ; Energy Concentration

[0049] Where: A1 is the fundamental meshing frequency of the gear pair in the spectrum. The amplitude, A2 is the second harmonic of the meshing frequency in the spectrum. The amplitude, A3 is the third harmonic of the meshing frequency in the spectrum. The amplitude, A4 is the fourth harmonic of the meshing frequency in the spectrum. The amplitude; For example, time-domain analysis: the peak value, root mean square value (RMS), peak factor (CF), and kurtosis of the stationary signal in the angular domain are calculated, and the results are shown in Table 1 below (taking standard wind pressure and 10 sppm as an example): Table 1

[0050] Based on time-domain indicators, both peak factor and kurtosis are within the normal range (peak factor 5~8, kurtosis 3~5), with no obvious shock anomalies. The Hanning window is used to suppress spectral leakage, and the amplitude spectrum is obtained through Fast Fourier Transform (FFT) to extract the meshing frequency and harmonic components. The high-speed stage meshing frequency f1 = 625 Hz, the first harmonic amplitude A1 = 0.85 g, the second harmonic amplitude A2 = 0.32 g, the third harmonic amplitude A3 = 0.15 g, and the fourth harmonic amplitude A4 = 0.08 g; Calculate the frequency domain characteristic parameters: octave amplitude ratio A2 / A1 = 0.388, energy concentration. ; S5. Bandpass filtering is applied to the stationary signal in the angular domain to extract the high-frequency signal. Then, Hilbert transform and envelope demodulation are performed on the high-frequency signal to extract the gear meshing impact envelope signal, and the envelope spectrum output envelope characteristic parameters are calculated. The specific steps of step S5 are as follows: S51. Construct a bandpass filter with the target center frequency and bandwidth, and use the constructed bandpass filter to extract a stationary signal from the angular domain. Extracting high-frequency resonance signals from them; For example, construct a bandpass filter with a center frequency of 2.5kHz and a bandwidth of 500Hz; S52. For high-frequency resonance signals The envelope signal is obtained by envelope demodulation using Hilbert transform. The specific steps are as follows: For high-frequency resonance signals Perform Hilbert transform to obtain the high-frequency resonant signal. orthogonal components The transformation formula is:

[0051] Where PV represents the Cauchy principal value integral; High-frequency resonance signal Orthogonal components of the Hilbert transform Combining to construct analytic signals :

[0052] Where j is the imaginary unit; Calculate analytic signals The modulus is the envelope signal. :

[0053] For example, a signal with a center frequency of 2~3kHz and a bandwidth of 500Hz is selected for Hilbert transform to extract the gear meshing impact envelope signal and calculate the envelope spectrum; S53. Perform a Fast Fourier Transform on the envelope signal to obtain the envelope spectrum, and calculate the envelope impact factor. : ; For example, a bandpass filter is applied to a stationary signal in the angular domain, with a center frequency of 2.5 kHz and a bandwidth of 500 Hz, to extract the high-frequency resonant signal; envelope demodulation is performed using Hilbert transform; and the orthogonal components of the high-frequency resonant signal are calculated. ; Constructing an analytic signal: ; Calculate the magnitude of the analytic signal to obtain the envelope signal: ; The envelope spectrum is obtained by performing an FFT on the envelope signal, and the envelope impact factor is calculated. ; S6. Analyze the sideband characteristics on both sides of the meshing frequency of the gear pair, and use time-frequency analysis to obtain the law of change of gear meshing characteristics with time, and output the sideband and time-frequency characteristic parameters; the specific steps of step S6 are as follows: S61. Identify the meshing frequency of the gear pair from the frequency spectrum. The distance between the two sides is the crankshaft rotational frequency. The border tribe; S62. Based on the amplitude information of the spectrum, calculate the ratio of the total energy of the first three sidebands in the sideband family to the energy of the main frequency, and use this ratio as the sideband energy ratio. :

[0054] Where k is the order of the sideband, and k = 1, 2, 3 is taken, that is, the first three orders of sidebands are summed; The frequency is equal to the meshing frequency. Add k times the crankshaft frequency The sideband amplitude, The frequency is equal to the meshing frequency. Subtract k times the frequency The sideband amplitude; Meshing frequency The amplitude; S63. Short-time Fourier transform is used to analyze stationary signals in the angular domain. By selecting the preset window function length and overlap rate, a time-frequency distribution map is generated to identify the maximum value of the impact signal energy that appears in the preset crank angle interval corresponding to the loading stage of the press, which is recorded as the time-frequency impact energy. For example, the short-time Fourier transform is used to analyze the stationary signal in the angular domain output of step S3. The window function length is 256 points and the overlap rate is 75%. A time-frequency distribution map is generated to identify the phenomenon of concentrated impact energy at the crank angle of 90°±30° (loading stage). For example, the family of sidebands on both sides of the meshing frequency is identified from the spectrum, and the spacing between the sidebands is equal to the crankshaft rotational frequency (low-speed stage rotational frequency n2 = 500 r / min, rotational frequency...). =500 / 60≈8.33Hz); Calculate the ratio of the total energy of the first three sidebands to the energy of the main frequency: ; Time-frequency analysis: Short-time Fourier transform (STFT) was used, with a window function length of 256 points and an overlap rate of 75%, to generate a time-frequency distribution map. The maximum energy value of the impact signal during the loading stage of the press (crank angle 90°±30°) was identified and denoted as the time-frequency impact energy E=0.35g. 2 Hz; S7. Based on time-domain characteristic indicators, frequency-domain characteristic parameters, envelope characteristic parameters, sideband and time-frequency characteristic parameters, perform gear meshing health evaluation and calculate the comprehensive health index HI to quantitatively assess the gear meshing state; the specific steps of step S7 are as follows: S71. The root mean square value in the time-domain characteristic index. Peak factor , cliff The ratio of the octave amplitude in the frequency domain characteristic parameters and the envelope impact factor in the envelope characteristic parameters. The parameters are compared with the corresponding parameters under healthy baseline conditions and then normalized. The normalization formula is as follows:

[0055] in, The current parameter value. Baseline parameter values, These are the normalized parameter values; S72. The comprehensive health index HI is calculated through weighted fusion, and its calculation formula is as follows:

[0056] in, This represents the normalized root mean square value. This represents the peak factor after normalization. Indicates the normalized kurtosis. This represents the normalized octave amplitude ratio. This represents the normalized envelope impact factor. , , , , Let be the weight coefficient, and satisfy... ; S73. Based on the comprehensive health index Assess the gear's condition and set a first health index threshold. Second health index threshold Third health index threshold ; in, The status assessment rules are as follows: like If so, the gear meshing state is determined to be normal; like If so, the gear meshing state is determined to be slightly uneven; like If so, the gear meshing condition is determined to be moderate wear; like If so, the gear meshing state is determined to be severely abnormal; For example ≤1.2 is normal, 1.2 < ≤1.5 indicates mild unevenness, 1.5 < ≤2.0 indicates moderate wear. A value >2.0 indicates a severe anomaly; In step S71, the sideband energy ratio in the sideband feature parameters and the time-frequency impact energy as the time-frequency feature parameters are normalized; And corresponding weighted terms are added to the calculation formula of the comprehensive health index in step S72 and , and :

[0057] where, is the normalized sideband energy ratio, is the normalized time-frequency impact energy; Exemplarily, the extracted feature parameters are compared with the healthy baseline data and normalized. The normalization formula is: , where is the current parameter value, is the baseline parameter value, is the normalized parameter value; The normalization results are shown in Table 2 below: Table 2

[0058] The weighted fusion algorithm is used to calculate the comprehensive health index HI, and the weight coefficients are determined according to the gear system structure characteristics and experimental statistics: = 0.2, = 0.15, = 0.2, = 0.2, = 0.15, = 0.05, = 0.05, satisfying ; The calculation formula is: Substituting the data for calculation gives: HI = 0.2×1.06 + 0.15×1.06 + 0.2×1.11 + 0.2×1.10 + 0.15×1.06 + 0.05×1.20 + 0.05×1.09 = 1.08; According to the health index threshold rule: HI ≤ 1.2: Normal; 1.2 < HI ≤ 1.5: Mild unevenness; 1.5 < HI ≤ 2.0: Moderate wear; HI > 2.0: Severe abnormality.

[0059] The HI calculated in this test is 1.08, determining that the gear meshing state of the press is normal, without obvious fault characteristics, and the meshing stiffness uniformity is good, and it can continue to operate normally.

[0060] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0061] like Figure 2 As shown, the following is an embodiment of the gear vibration testing device for a two-stage transmission press provided in this disclosure. This system and the gear vibration testing method for a two-stage transmission press in the above embodiments belong to the same inventive concept. For details not described in detail in the embodiments of the gear vibration testing device for a two-stage transmission press, please refer to the embodiments of the gear vibration testing method for a two-stage transmission press described above.

[0062] The two-stage transmission press includes a flywheel, a high-speed gearbox connected to the flywheel, a low-speed gearbox connected to the output shaft of the high-speed gearbox, a crank-slider mechanism driven by a crankshaft output from the low-speed gearbox, and a balancer cylinder for balancing the weight of the slider in the crank-slider mechanism. A cam sensor for detecting the rotational angle of the crankshaft is provided on the crankshaft. The device includes: The sensor arrangement and synchronization module is used to arrange several sets of triaxial acceleration sensors on the outer walls of the high-speed gearbox and the low-speed gearbox, and at the same time extract the cam sensor signal to realize the synchronous acquisition of vibration signal and crankshaft angle signal. The multi-condition synchronous acquisition module is used to set different combinations of balancer air pressure and different slider speeds in the operation of the secondary press, and to acquire vibration signals and crankshaft angle signals under each condition in a multi-channel synchronous manner. The signal preprocessing module is used to perform anti-aliasing filtering, detrending and bandpass filtering on the acquired vibration signal, and to perform angular domain resampling using the crankshaft angle signal to output a stationary angular domain signal. The time-frequency feature extraction module is used to perform time-domain and frequency-domain analysis on stationary signals in the angular domain, and outputs time-domain feature indices, gear pair meshing frequency, and frequency-domain feature parameters. The envelope demodulation analysis module is used to perform bandpass filtering on the angular domain stationary signal to extract the high-frequency signal, then perform Hilbert transform envelope demodulation on the high-frequency signal to extract the gear meshing impact envelope signal, and calculate the envelope spectrum output envelope feature parameters. The sideband and time-frequency analysis module is used to analyze the sideband characteristics on both sides of the meshing frequency of the gear pair, and to obtain the law of gear meshing characteristics changing with time using time-frequency analysis method, and output sideband and time-frequency characteristic parameters; The health status assessment module is used to evaluate gear meshing health based on time-domain characteristic indicators, frequency-domain characteristic parameters, envelope characteristic parameters, sideband and time-frequency characteristic parameters, and calculate the comprehensive health index HI to quantitatively assess the gear meshing status.

[0063] This embodiment achieves accurate identification of early gear failures through non-invasive monitoring and multi-dimensional signal analysis by using the interactive collaboration of sensor placement and synchronization module, multi-condition synchronous acquisition module, signal preprocessing module, time-frequency feature extraction module, envelope demodulation analysis module, sideband and time-frequency analysis module, and health status assessment module. It adapts to various complex working conditions, effectively improves equipment operating efficiency and reliability, reduces maintenance costs, and provides a reasonable basis for press health monitoring.

[0064] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for testing gear vibration in a two-stage transmission press, the two-stage transmission press comprising a flywheel, a high-speed gearbox connected to the flywheel, a low-speed gearbox connected to the output shaft of the high-speed gearbox, a crank-slider mechanism driven by a crankshaft output from the low-speed gearbox, and a balancer cylinder for balancing the weight of the slider in the crank-slider mechanism, wherein a cam sensor for detecting the rotational angle position of the crankshaft is provided on the crankshaft; characterized in that, The method includes the following steps: S1. Several sets of triaxial acceleration sensors are arranged on the outer walls of the high-speed gearbox and the low-speed gearbox, and the cam sensor signal is brought out at the same time to realize the synchronous acquisition of vibration signal and crankshaft angle signal. S2. Under the operation of the secondary press, set up different combinations of balancer air pressure and different slider speeds, and collect vibration signals and crankshaft angle signals under each working condition in a multi-channel synchronous manner. S3. Perform anti-aliasing filtering, detrending and bandpass filtering on the acquired vibration signal, and use the crankshaft angle signal for angular domain resampling to output a stable angular domain signal; S4. Perform time-domain and frequency-domain analysis on the stationary signal in the angle domain, and output the time-domain characteristic index, gear pair meshing frequency and frequency-domain characteristic parameters; S5. Bandpass filtering is performed on the stationary signal in the angular domain to extract the high-frequency signal. Then, Hilbert transform is performed on the high-frequency signal for envelope demodulation to extract the gear meshing impact envelope signal and calculate the envelope spectrum output envelope characteristic parameters. S6. Analyze the sideband characteristics on both sides of the meshing frequency of the gear pair, and use time-frequency analysis to obtain the law of gear meshing characteristics changing with time, and output the sideband and time-frequency characteristic parameters; S7. Based on time-domain characteristic indicators, frequency-domain characteristic parameters, envelope characteristic parameters, sideband and time-frequency characteristic parameters, gear meshing health is evaluated, and the comprehensive health index HI is calculated to quantitatively assess the gear meshing state.

2. The gear vibration testing method for a two-stage transmission press according to claim 1, characterized in that, The specific steps of step S1 are as follows: S11. A set of three-dimensional acceleration sensors is arranged on the front left, rear left, front right, and rear right covers of the low-speed gearbox, and the sensitive axis of each set of three-dimensional acceleration sensors is perpendicular to the mounting surface. S12. A set of three-dimensional acceleration sensors is arranged directly above the intermediate shaft bearing cover of the high-speed gearbox; S13. Connect the pulse signal from the cam sensor to the rotation speed channel of the signal acquisition system via a shielded wire, and connect each triaxial acceleration sensor to the vibration channel of the signal acquisition system.

3. The gear vibration testing method for a two-stage transmission press according to claim 2, characterized in that, The specific steps of step S2 are as follows: S21. Set the balancer's air pressure to three operating conditions: standard air pressure, low air pressure, and high air pressure. S22. Set at least three different slider operating speeds for each wind pressure condition; S23. Under each combination of wind pressure and speed, the vibration signals of all three-dimensional acceleration sensors and the crankshaft angle signal of the cam sensor are collected synchronously at a preset sampling frequency, and the continuous collection time meets the time length threshold.

4. The gear vibration testing method for a two-stage transmission press according to claim 3, characterized in that, The specific steps of step S3 are as follows: S31. The original vibration signal is sequentially subjected to anti-aliasing filtering and linear detrending term processing according to the preset cutoff frequency signal; S32. Set a bandpass filter for filtering based on the estimated gear meshing frequency range; S33. Based on the acquired crankshaft angle signal, the filtered time-domain vibration signal is resampled into a stationary angular domain signal with equal angular intervals using cubic spline interpolation. Specifically, for time series and corresponding vibration signals The interval formed, the cubic polynomial constructed and the second derivative of a cubic polynomial The following system of equations is satisfied: in, In order to keep pace with time The corresponding crankshaft angular coordinates, , , and They are cubic, quadratic, linear, and constant terms, respectively, along with time. The corresponding coefficients; Set target interpolation point (k=1,2,...,N) represents N uniform angle points per revolution. The interpolated angular domain stationary signal is obtained by solving the system of equations. .

5. The gear vibration testing method for a two-stage transmission press according to claim 4, characterized in that, The specific steps of step S4 are as follows: S41. Calculate the stationary signal in the angular domain peak Root mean square value Peak factor and kurtosis As a time-domain characteristic indicator; Where μ is the angular-domain stationary signal The mean of σ is the stationary signal in the angular domain. The standard deviation of N, where N is the number of sampling points. Let n be the vibration signal amplitude corresponding to the nth angular sampling point, where n is the sampling point number of the stationary signal in the angular domain, n=1,2,3,...,N; S42. Diagonal stationary signal Perform a Fast Fourier Transform to obtain the spectrum, and identify and extract the meshing frequency of the gear pair from the spectrum. : in, This refers to the number of teeth on the gear. The crankshaft rotational frequency; S43. Calculate frequency domain characteristic parameters: frequency doubling amplitude ratio ; Energy Concentration Where: A1 is the fundamental meshing frequency of the gear pair in the spectrum. The amplitude, A2 is the second harmonic of the meshing frequency in the spectrum. The amplitude, A3 is the third harmonic of the meshing frequency in the spectrum. The amplitude, A4 is the fourth harmonic of the meshing frequency in the spectrum. The amplitude.

6. The gear vibration testing method for a two-stage transmission press according to claim 5, characterized in that, The specific steps of step S5 are as follows: S51. Construct a bandpass filter with the target center frequency and bandwidth, and use the constructed bandpass filter to extract a stationary signal from the angular domain. Extracting high-frequency resonance signals from them; S52. For high-frequency resonance signals The envelope signal is obtained by envelope demodulation using Hilbert transform. The specific steps are as follows: For high-frequency resonance signals Perform Hilbert transform to obtain the high-frequency resonant signal. orthogonal components The transformation formula is: Where PV represents the Cauchy principal value integral; High-frequency resonance signal Orthogonal components of the Hilbert transform Combining to construct analytic signals : Where j is the imaginary unit; Calculate analytic signals The modulus is the envelope signal. : S53. Perform a Fast Fourier Transform on the envelope signal to obtain the envelope spectrum, and calculate the envelope impact factor. : 。 7. The gear vibration testing method for a two-stage transmission press according to claim 6, characterized in that, The specific steps of step S6 are as follows: S61. Identify the meshing frequency of the gear pair from the frequency spectrum. The distance between the two sides is the crankshaft rotational frequency. The border tribe; S62. Based on the amplitude information of the spectrum, calculate the ratio of the total energy of the first three sidebands in the sideband family to the energy of the main frequency, and use this ratio as the sideband energy ratio. : Where k is the order of the sideband, and k = 1, 2, 3 is taken, that is, the first three orders of sidebands are summed; The frequency is equal to the meshing frequency. Add k times the crankshaft frequency The sideband amplitude, The frequency is equal to the meshing frequency. Subtract k times the frequency The sideband amplitude; Meshing frequency The amplitude; S63. Short-time Fourier transform is used to analyze stationary signals in the angular domain. By selecting a preset window function length and overlap rate, a time-frequency distribution map is generated to identify the maximum value of the impact signal energy occurring within a preset crank angle interval corresponding to the loading stage of the press, which is denoted as the time-frequency impact energy. .

8. The gear vibration testing method for a two-stage transmission press according to claim 7, characterized in that, The specific steps of step S7 are as follows: S71. The root mean square value in the time-domain characteristic index. Peak factor , cliff The ratio of the octave amplitude in the frequency domain characteristic parameters and the envelope impact factor in the envelope characteristic parameters. The parameters are compared with the corresponding parameters under healthy baseline conditions and then normalized. The normalization formula is as follows: in, The current parameter value. Baseline parameter values, These are the normalized parameter values; S72. The comprehensive health index HI is calculated through weighted fusion, and its calculation formula is as follows: in, This represents the normalized root mean square value. This represents the peak factor after normalization. Indicates the normalized kurtosis. This represents the normalized octave amplitude ratio. This represents the normalized envelope impact factor. , , , , Let be the weight coefficient, and satisfy... ; S73. Based on the comprehensive health index Assess the gear's condition and set a first health index threshold. Second health index threshold Third health index threshold ; in, The status assessment rules are as follows: like If so, the gear meshing state is determined to be normal; like If so, the gear meshing state is determined to be slightly uneven; like If so, the gear meshing condition is determined to be moderate wear; like If so, the gear meshing state is determined to be severely abnormal.

9. The gear vibration testing method for a two-stage transmission press according to claim 8, characterized in that, In step S71, the sideband energy ratio in the sideband characteristic parameters is also... and time-frequency impact energy as a time-frequency characteristic parameter Perform normalization; And the comprehensive health index in step S72 Add corresponding weighting terms to the calculation formula and ,and : in, The normalized sideband energy ratio. This is the normalized time-frequency impact energy.

10. A gear vibration testing device for a two-stage transmission press, the two-stage transmission press comprising a flywheel, a high-speed gearbox connected to the flywheel, a low-speed gearbox connected to the output shaft of the high-speed gearbox, a crank-slider mechanism driven by a crankshaft output from the low-speed gearbox, and a balancer cylinder for balancing the weight of the slider in the crank-slider mechanism, wherein a cam sensor for detecting the rotational angle position of the crankshaft is provided on the crankshaft; characterized in that, include: The sensor arrangement and synchronization module is used to arrange several sets of triaxial acceleration sensors on the outer walls of the high-speed gearbox and the low-speed gearbox, and at the same time extract the cam sensor signal to realize the synchronous acquisition of vibration signal and crankshaft angle signal. The multi-condition synchronous acquisition module is used to set different combinations of balancer air pressure and different slider speeds in the operation of the secondary press, and to acquire vibration signals and crankshaft angle signals under each condition in a multi-channel synchronous manner. The signal preprocessing module is used to perform anti-aliasing filtering, detrending and bandpass filtering on the acquired vibration signal, and to perform angular domain resampling using the crankshaft angle signal to output a stationary angular domain signal. The time-frequency feature extraction module is used to perform time-domain and frequency-domain analysis on stationary signals in the angular domain, and outputs time-domain feature indices, gear pair meshing frequency, and frequency-domain feature parameters. The envelope demodulation analysis module is used to perform bandpass filtering on the angular domain stationary signal to extract the high-frequency signal, then perform Hilbert transform envelope demodulation on the high-frequency signal to extract the gear meshing impact envelope signal, and calculate the envelope spectrum output envelope feature parameters. The sideband and time-frequency analysis module is used to analyze the sideband characteristics on both sides of the meshing frequency of the gear pair, and to obtain the law of gear meshing characteristics changing with time using time-frequency analysis method, and output sideband and time-frequency characteristic parameters; The health status assessment module is used to evaluate gear meshing health based on time-domain characteristic indicators, frequency-domain characteristic parameters, envelope characteristic parameters, sideband and time-frequency characteristic parameters, and calculate the comprehensive health index HI to quantitatively assess the gear meshing status.

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