An ultrasonic vibration working condition gas film dynamic stability detection device and detection method

Abstract

This invention provides a device and method for detecting the dynamic stability of an air film under ultrasonic vibration conditions. The device comprises a testing carriage, a vibration data acquisition device, and a controller. The testing carriage includes a mounting housing, a working shaft, and an ultrasonic excitation transducer. The mounting housing has transducer mounting positions and bearing mounting positions for mounting the ultrasonic excitation transducer and the air bearing, respectively. The working shaft is disposed in the central hole of the air bearing, and its lower end is connected to the ultrasonic excitation transducer. The vibration data acquisition device acquires vibration data from the working shaft, and the controller evaluates the dynamic stability of the air film under ultrasonic vibration conditions based on the vibration data. The advantages are: it can simulate the high-frequency dynamic load borne by the air bearing under actual ultrasonic processing conditions, and simultaneously collect vibration data from the working shaft using multiple vibration data acquisition devices, combined with the detection method to achieve dynamic stability detection of the air film.

Description

Technical Field

[0001] This invention relates to the field of air bearing stability testing technology, specifically to a device and method for testing the dynamic stability of air film under ultrasonic vibration conditions. Background Technology

[0002] Ultrasonic air-bearing spindles significantly improve the precision machining performance of microstructures in hard and brittle materials and are now widely used in high-end precision manufacturing fields such as optical devices and semiconductor equipment. These spindles use a micron-level air film as the core support medium, achieving near-frictionless lubrication while ensuring support rigidity. This effectively meets the stringent requirements of high-precision machining for equipment motion stability and workpiece surface quality. However, during spindle operation, the ultrasonic system introduces high-frequency ultrasonic vibrations of 20kHz–60kHz, leading to complex coupling between the working shaft and the air bearing. Because the air film thickness is only on the micron scale, the periodic displacement disturbances generated by ultrasonic vibrations easily cause transient changes in the air film gap, resulting in drastic fluctuations in the air film pressure distribution. When the amplitude and frequency of the ultrasonic vibrations are mismatched with the structural parameters of the air bearing and the air supply conditions, it can directly induce air film instability, potentially leading to complete failure of gas lubrication and irreversible structural damage to the air bearing in the ultrasonic air-bearing spindle.

[0003] Currently available performance testing equipment and technologies for air bearings are designed for conventional working conditions and can only test the bearing's load-bearing capacity, static air film thickness, and low-frequency vibration parameters. For example, patent CN112146881 discloses a vibration offset detection device for air bearings, which can simultaneously detect the lateral and vertical vibration offset of air bearings and comprehensively reflect the vibration characteristics of air bearings under conventional working conditions. However, this patent uses a contact vibration detection structure, which cannot meet the testing requirements for the vibration resistance of air bearings under ultrasonic conditions. Summary of the Invention

[0004] To address the problems in the prior art, this invention provides a device for testing the dynamic stability of air film under ultrasonic vibration conditions. This solves the problem that existing air bearing performance testing equipment cannot meet the testing requirements for the vibration resistance of air bearings under ultrasonic conditions.

[0005] This invention discloses a device for detecting the dynamic stability of an air film under ultrasonic vibration conditions. The device includes a testing carrier, a vibration data acquisition device, and a controller. The testing carrier comprises a mounting housing, a working shaft, and an ultrasonic excitation transducer. The mounting housing has transducer mounting positions and bearing mounting positions for mounting the ultrasonic excitation transducer and an air bearing, respectively. The working shaft is disposed in the central hole of the air bearing, and its lower end is connected to the ultrasonic excitation transducer. The working shaft vibrates under the drive of the ultrasonic excitation transducer. The vibration data acquisition device acquires the vibration data information of the working shaft and outputs it to the controller. The controller evaluates the dynamic stability of the air film under ultrasonic vibration conditions based on the vibration data information.

[0006] The present invention is further improved in that the vibration data acquisition device includes a first vibration detector and a second vibration detector. The first vibration detector is disposed above the testing vehicle, and the detection direction of the first vibration detector is parallel to the axial direction of the air bearing. The first vibration detector can detect vibration data information in the axial direction of the working shaft. The second vibration detector is disposed on the side of the testing vehicle, and the detection direction of the second vibration detector is perpendicular to the axial direction of the air bearing. The second vibration detector can detect vibration data information in the radial direction of the working shaft.

[0007] The invention is further improved by using a laser Doppler vibration meter as the vibration data acquisition device.

[0008] The present invention is further improved by using a piezoelectric ultrasonic excitation transducer.

[0009] The present invention is further improved so that the resonant frequency range of the ultrasonic excitation transducer is 20kHz-100kHz.

[0010] The invention is further improved by including an air stop plate and a front cover on the testing carrier. The front cover and the air stop plate are respectively fixedly attached to the upper and lower end faces of the air bearing. The front cover and the air stop plate are respectively provided with a first clearance hole and a second clearance hole that cooperate with the working shaft. A working convex ring is provided on the outer periphery of the upper end of the working shaft. The working convex ring is located in the first clearance hole and cooperates with the upper end face of the air bearing.

[0011] This invention also provides a method for detecting the dynamic stability of an air film under ultrasonic vibration conditions, comprising the following steps: Step S1: Preset the ultrasonic excitation frequency detection group parameters for multiple ultrasonic excitation transducers; Step S2: Start the ultrasonic excitation transducer. According to the parameters of each ultrasonic excitation frequency detection group, the ultrasonic excitation transducer outputs ultrasonic vibration consistent with the set parameters. The ultrasonic vibration is transmitted to the working shaft through the front end of the ultrasonic excitation transducer. Step S3: In each ultrasonic excitation frequency detection group, the vibration data acquisition device continuously acquires the raw vibration data of the working shaft for a specified time and transmits the raw vibration data to the controller in real time. Step S4: The signal processing unit of the controller analyzes the raw vibration data received from each ultrasonic excitation frequency detection group, extracts the vibration frequency and vibration amplitude, maps the vibration amplitude to the time axis, obtains the time domain signal, draws the time domain waveform based on the time domain signal, evaluates the stability of the air film based on the time domain waveform, and identifies the abnormal characteristics of the air film. Step S5: Convert the time-domain signal into a frequency-domain signal to generate a vibration spectrum. Based on the abnormal characteristics, focus on analyzing the spectral peaks with prominent amplitudes in the corresponding spectrum, locate the abrupt change points of the spectral characteristics, and determine the critical excitation conditions for gas film instability.

[0012] The present invention is further improved, and step S1 specifically includes: To connect the air bearing to the high-pressure air supply system, adjust the air supply pressure to the preset stable value, and complete the static support construction after the air film is formed and stabilized. The signal output terminals of the first and second vibration detectors are synchronously connected to the signal processing unit of the controller, and the sampling frequency that meets the requirements of ultrasonic frequency band acquisition is set to complete the zero-point calibration and synchronous trigger setting of the detection system. Multiple typical ultrasonic processing frequency bands are selected as reference excitation frequencies, and multiple typical processing amplitudes are selected as reference amplitudes. Multiple sets of ultrasonic excitation frequency detection parameters are preset based on the reference excitation frequencies and reference amplitudes.

[0013] The present invention is further improved, and step S4 specifically includes: The controller's signal processing unit first preprocesses the raw vibration data, then maps the vibration amplitude to the time axis to obtain the time domain signal and plots the time domain waveform. Key time-domain feature parameters, including vibration peak value, RMS value, root mean square value, and kurtosis, are extracted based on the time-domain waveform. Observe the stationarity of the time-domain waveform to determine the variation of vibration amplitude with excitation parameters; Identify anomalous features of the air film based on key time-domain characteristics, including abrupt shocks, waveform distortion, and amplitude divergence, and locate the time-domain range of the anomalous period.

[0014] The present invention is further improved, and step S5 specifically includes: Perform a fast Fourier transform on the time-domain signal to convert it into a frequency-domain signal and generate a vibration spectrum. Based on the abnormal time periods marked in step S4, focus on analyzing the spectral peaks with prominent amplitudes in the corresponding spectrum, and identify and extract the main oscillation frequency and its corresponding amplitude. By tracking the amplitude and harmonic component changes of characteristic frequencies under different excitation conditions, the frequency evolution law of air film vibration is analyzed. When a frequency sub-component or a sudden increase in high-frequency harmonic energy appears in the spectrum, it is determined to be the critical point of gas film instability, and the corresponding critical excitation frequency and critical excitation amplitude are extracted. Based on all critical point data, the stability-instability boundary curves of the air film were plotted to clarify the stable operating range of the air film under different working conditions.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a device for testing the dynamic stability of air film under ultrasonic vibration conditions. Its structure effectively solves the problem that existing air bearing performance testing equipment cannot meet the testing requirements for the vibration resistance of air bearings under ultrasonic conditions. Through the cooperation of an ultrasonic excitation transducer and a working shaft, the ultrasonic excitation transducer applies controllable ultrasonic frequency vibration excitation to the working shaft, simulating the high-frequency dynamic load borne by the air bearing under actual ultrasonic processing conditions. Simultaneously, a vibration data acquisition device collects the vibration data of the working shaft in real time. Signal analysis is used to analyze the vibration data, extracting the corresponding curves of vibration frequency and amplitude changes with excitation, and the vibration characteristic parameters of the critical excitation conditions for air film instability. This enables quantitative evaluation of the dynamic stability of the air film under ultrasonic vibration conditions. Attached Figure Description

[0016] To more clearly illustrate the solutions in this invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of the air film dynamic stability testing device under ultrasonic vibration conditions. The dashed line in the figure represents the detection direction of the vibration data acquisition device. Figure 2 This is a schematic diagram of the test vehicle structure; Figure 3 for Figure 2 Cross-sectional view along the AA direction; Figure 4 This is a flowchart of a method for detecting the dynamic stability of an air film under ultrasonic vibration conditions. Detailed Implementation

[0018] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings are used to distinguish different objects, not to describe a particular order.

[0019] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment to other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0021] like Figure 1-3 As shown, the present invention discloses a device for detecting the dynamic stability of an air film under ultrasonic vibration conditions, comprising a detection carrier 1, a vibration data acquisition device, and a controller. The detection carrier 1 includes a mounting housing 10, a working shaft 11, and an ultrasonic excitation transducer 14. The mounting housing 10 is respectively provided with a transducer mounting position and a bearing mounting position for mounting the ultrasonic excitation transducer 14 and the air bearing 13. The working shaft 11 is disposed in the axial hole 131 of the air bearing 13. The lower end of the working shaft 11 is connected to the ultrasonic excitation transducer 14. The working shaft 11 vibrates under the drive of the ultrasonic excitation transducer 14. The vibration data acquisition device acquires the vibration data information of the working shaft 11 and outputs it to the controller. The controller evaluates the dynamic stability of the air film under ultrasonic vibration conditions based on the vibration data information.

[0022] By cooperating with the ultrasonic excitation transducer 14 and the working shaft 11, the ultrasonic excitation transducer 14 applies controllable ultrasonic frequency band vibration excitation to the working shaft, simulating the high-frequency dynamic load borne by the air bearing under actual ultrasonic processing conditions. At the same time, the vibration data of the working shaft 11 is collected by the vibration data acquisition device, thereby obtaining dynamic load information data of different frequency bands borne by the air bearing 13, providing data support for the dynamic stability detection of the air film, and meeting the data acquisition requirements for the vibration resistance detection of the air bearing under ultrasonic conditions.

[0023] The vibration data acquisition device includes a first vibration detector 21 and a second vibration detector 22. The first vibration detector 21 is positioned above the testing carrier 1, and its detection direction is parallel to the axial direction of the air bearing 13. The second vibration detector 22 is positioned on the side of the testing carrier 1, and its detection direction is perpendicular to the axial direction of the air bearing 13.

[0024] By setting up two vibration data acquisition devices, two sensing channels are arranged in an orthogonal direction in space.

[0025] The first vibration detector 21 serves as an axial vibration detection channel. The detection direction of the first vibration detector 21 is parallel to the axial direction of the air bearing 13. It is used to collect the dynamic response of the working shaft 11 in the axial direction, thereby reflecting the vibration of the air film between the air bearing and the working shaft in the axial direction.

[0026] The second vibration detector 22 serves as a radial vibration detection channel. The detection direction of the second vibration detector 22 is perpendicular to the axial direction of the air bearing 13. It is used to collect the dynamic response of the working shaft 11 in the radial direction, thereby reflecting the vibration of the air film between the air bearing and the working shaft in the radial direction.

[0027] Data acquisition is performed synchronously by the signal processors of the two vibration meters to ensure the temporal consistency of axial and radial vibration signals, providing a data foundation for subsequent coupling analysis.

[0028] The vibration data acquisition device is a laser Doppler vibration meter. Obviously, there are other options for the vibration data acquisition device, and it is not limited to this vibration measuring instrument. For example, a piezoelectric vibration acceleration sensor is also within the protection scope of this solution.

[0029] The ultrasonic excitation transducer 14 is a piezoelectric ultrasonic excitation transducer that realizes ultrasonic vibration. The application of the piezoelectric ultrasonic excitation transducer described in the embodiment is not limited to this type. It can also be replaced by ultrasonic excitation transducers such as magnetostrictive ultrasonic excitation transducers or electromagnetic ultrasonic excitation transducers, which are also within the protection scope of this solution.

[0030] The resonant frequency range of the ultrasonic excitation transducer 14 is 20kHz-100kHz. In this embodiment, three frequencies of 20kHz, 40kHz and 60kHz are used as adjustment options. By setting the three frequencies, adjustments can be made according to requirements, improving the flexibility of the detection device.

[0031] The testing carrier 1 also includes an air stop plate 15 and a front cover 16. The front cover 16 and the air stop plate 15 are fixedly attached to the upper end face and the lower end face of the air bearing 13, respectively. The front cover 16 and the air stop plate 15 are respectively provided with a first clearance hole 161 and a second clearance hole 151 that cooperate with the working shaft 11. A working convex ring 112 is provided on the outer periphery of the upper end of the working shaft 11. The working convex ring 112 is located in the first clearance hole 161 and cooperates with the upper end face of the air bearing 13.

[0032] By setting the gas stop plate 15, the gas in the air bearing 13 can be sealed, and the gas film thickness can be controlled (the gas stop plate 15 is processed according to the size of the working shaft 11 and the size of the air bearing 13 to control the formation of a controllable 5-30μm micron-level gas film between the air outlet support end of the air bearing 13 and the working shaft 11).

[0033] An air flow channel is provided inside the air bearing 13, and an air outlet hole is provided on the upper end face of the air bearing 13. The air flow channel is connected to the air outlet hole. The gas in the air flow channel flows out from the air outlet hole and flows through the lower end face of the working convex ring 112, so that a stable air film is formed between the upper end face of the air bearing 13 and the lower end face of the working convex ring 112.

[0034] The transducer mounting position is a mounting cavity 100 set in the mounting housing 10. The inner wall of the mounting cavity 100 is provided with a mounting step 101. The ultrasonic excitation transducer 14 is provided with a mounting limiting member 141 that cooperates with the mounting step 101. The mounting limiting member 141 is limited and connected to the upper end face of the mounting step 101.

[0035] The lower end of the working shaft 11 is provided with a mounting groove 111 that mates with the ultrasonic excitation transducer 14, and the output end of the ultrasonic excitation transducer 14 is located in the mounting groove 111.

[0036] like Figure 4 As shown, the present invention also provides a method for detecting the dynamic stability of an air film under ultrasonic vibration conditions, which is implemented based on the above-mentioned device for detecting the dynamic stability of an air film under ultrasonic vibration conditions, and includes the following steps: Step S1: Preset the ultrasonic excitation frequency detection group parameters for multiple ultrasonic excitation transducers 14.

[0037] Connect the air bearing 13 to the high-pressure air supply system, adjust the air supply pressure to 0.4-0.6MPa, and after the air film forms and stabilizes for 30 seconds, complete the static support construction.

[0038] A first vibration detector 21 is arranged above the testing vehicle 1, with its testing direction parallel to the axial direction of the air bearing 13; a second vibration detector 22 is arranged to the side of the testing vehicle 1, with its testing direction perpendicular to the axial direction of the air bearing 13.

[0039] The signal output terminals of the first vibration detector 21 and the second vibration detector 22 are synchronously connected to the signal processing unit of the controller, and the sampling frequency is set to ≥1MHz to complete the zero-point calibration and synchronous triggering settings of the detection system.

[0040] In this embodiment, three typical ultrasonic processing frequency bands of 20kHz, 40kHz, and 60kHz are used as reference excitation frequencies, and 1μm, 3μm, and 5μm are used as reference amplitudes. The ultrasonic excitation frequency detection parameters of the ultrasonic excitation transducer 14 are preset according to the reference excitation frequencies and reference amplitudes. Method 1: Fix the excitation frequency, lock it at 20kHz, 40kHz and 60kHz respectively, and increase the vibration amplitude from 0.1μm to 5μm in increments of 0.5μm, thereby setting three sets of ultrasonic excitation frequency detection parameters; Method 2: Fix the excitation amplitude, lock it at 1μm, 3μm and 5μm respectively, and switch the three frequency levels of 20kHz, 40kHz and 60kHz in sequence to set three sets of ultrasonic excitation frequency detection parameters.

[0041] Step S2: Start the ultrasonic excitation transducer 14. According to the parameters of each ultrasonic excitation frequency detection group, the ultrasonic excitation transducer 14 outputs ultrasonic vibration consistent with the set parameters. The ultrasonic vibration is transmitted to the working shaft 11 through the front end of the ultrasonic excitation transducer 14.

[0042] According to the parameters of the preset ultrasonic excitation frequency detection group, the ultrasonic excitation transducer 14 applies ultrasonic excitation to each group one by one. The ultrasonic excitation transducer 14 outputs ultrasonic vibration with a specified frequency and amplitude. The vibration is transmitted to the working shaft 11 to simulate the dynamic load borne by the air film under actual ultrasonic processing conditions.

[0043] Step S3: In each ultrasonic excitation frequency detection group, the vibration data acquisition device continuously acquires the original vibration data of the working shaft 11 for a specified time and transmits the original vibration data to the controller in real time.

[0044] The first vibration detector 21 collects the vibration frequency and amplitude of the working shaft 11 in real time, thereby reflecting the vibration of the air film between the air bearing 13 and the working shaft 11 in the axial direction.

[0045] The second vibration detector 22 collects the radial vibration frequency and amplitude of the working shaft 11 in real time, thereby reflecting the vibration of the air film between the air bearing 13 and the working shaft 11 in the radial direction.

[0046] The data is continuously collected for 10-15 seconds under the excitation parameters of each ultrasonic excitation frequency detection group. The raw vibration data is then transmitted in real time to the signal processing unit of the controller to ensure complete time-domain synchronization of the axial and radial signals.

[0047] The excitation parameter tests of all ultrasonic excitation frequency detection groups were completed in sequence to obtain the raw data of the dynamic response of the air film under different ultrasonic conditions.

[0048] Step S4: The signal processing unit of the controller analyzes the raw vibration data received from each ultrasonic excitation frequency detection group, extracts the vibration frequency and vibration amplitude, maps the vibration amplitude to the time axis, obtains the time domain signal, draws the time domain waveform based on the time domain signal, evaluates the stability of the air film based on the time domain waveform, and identifies abnormal characteristics of the air film.

[0049] The controller's signal processing unit preprocesses the raw vibration data: Time-domain waveform analysis: (1) Map the amplitude of vibration data to the time axis to obtain the time-domain signal, generate a complete time-domain waveform based on the time-domain signal, and intuitively present the characteristics of vibration change over time; (2) Based on the time-domain waveform diagram, extract key time-domain features: peak value, effective value, root mean square value (reflecting vibration intensity), kurtosis (reflecting impact characteristics), and other indicators; (3) Based on the time-domain waveform diagram, observe the stability of the waveform and determine whether the vibration amplitude changes regularly with the increase of excitation; (4) Identify abnormal features based on key time domain features: check whether there are signs of instability such as sudden shocks, waveform distortion, amplitude divergence, etc., and locate the time domain range of the abnormal period.

[0050] The vibration waveform curves plotted based on time-domain waveform analysis visually present the evolution law of air film vibration with excitation parameters; Step S5: Convert the time-domain signal into a frequency-domain signal to generate a vibration spectrum. Based on the abnormal characteristics, focus on analyzing the spectral peaks with prominent amplitudes in the corresponding spectrum, locate the abrupt change points of the spectral characteristics, and determine the critical excitation conditions for gas film instability.

[0051] Perform spectrum analysis on the data after time-domain waveform analysis: (1) Based on the time-domain waveform analysis results, perform a fast Fourier transform (FFT) on the time-domain signal to convert the time-domain signal into a frequency-domain signal and generate a vibration spectrum diagram; (2) Based on the abnormal time periods marked by time-domain analysis, focus on analyzing the spectral peaks with prominent amplitudes in the corresponding spectra; (3) Identify and extract the dominant frequency and the amplitude at the corresponding frequency to clarify the main source of vibration; (4) Analyze the spectrum changes under different excitation conditions step by step: track the amplitude changes and harmonic component changes of characteristic frequencies to determine the frequency evolution law of air film vibration; (5) Locate the abrupt change point of the spectrum characteristics (such as the appearance of frequency sub-components or a sudden increase in high-frequency harmonic energy, which is determined to be the critical point of gas film instability), determine the critical excitation conditions corresponding to gas film instability, extract the critical frequency and critical amplitude of gas film instability, and clarify the boundaries between stability and instability.

[0052] Based on the generated vibration waveform curves and spectrum analysis results, the critical point of air film instability is identified: when the vibration amplitude increases abruptly with the increase of excitation parameters, or when non-excitation frequency noise components appear in the spectrum and their energy surges, it is determined to be an air film instability state. The critical excitation frequency and critical excitation amplitude corresponding to this critical point are extracted, and the air film stability-instability boundary curve is plotted to clarify the stable operating range of the air film under different working conditions. This enables the detection of the dynamic stability of the air film and provides direct experimental basis for the structural optimization of the air bearing 13, the matching of air supply parameters, and the design of vibration suppression schemes.

[0053] The specific embodiments described above are preferred embodiments of the present invention and are not intended to limit the specific scope of the present invention. The scope of the present invention includes, but is not limited to, these specific embodiments. All equivalent changes made in accordance with the present invention are within the protection scope of the present invention.

Claims

1. A device for detecting the dynamic stability of an air film under ultrasonic vibration conditions, used to detect the air film formed between an air bearing and a working shaft, characterized in that: The system includes a testing vehicle, a vibration data acquisition device, and a controller. The testing vehicle includes a mounting housing, a working shaft, and an ultrasonic excitation transducer. The mounting housing is provided with a transducer mounting position and a bearing mounting position for mounting the ultrasonic excitation transducer and an air bearing, respectively. The working shaft is disposed in the central hole of the air bearing, and the lower end of the working shaft is connected to the ultrasonic excitation transducer. The working shaft vibrates under the drive of the ultrasonic excitation transducer. The vibration data acquisition device acquires the vibration data information of the working shaft and outputs it to the controller. The controller evaluates the dynamic stability of the air film under ultrasonic vibration conditions based on the vibration data information.

2. The device for detecting the dynamic stability of air film under ultrasonic vibration conditions according to claim 1, characterized in that: The vibration data acquisition device includes a first vibration detector and a second vibration detector. The first vibration detector is disposed above the testing vehicle, and its detection direction is parallel to the axial direction of the air bearing. The first vibration detector can detect vibration data information in the axial direction of the working shaft. The second vibration detector is disposed on the side of the testing vehicle, and its detection direction is perpendicular to the axial direction of the air bearing. The second vibration detector can detect vibration data information in the radial direction of the working shaft.

3. The device for detecting the dynamic stability of air film under ultrasonic vibration conditions according to claim 1, characterized in that: The vibration data acquisition device is a laser Doppler vibration meter.

4. The device for detecting the dynamic stability of air film under ultrasonic vibration conditions according to claim 1, characterized in that: The ultrasonic excitation transducer is a piezoelectric ultrasonic excitation transducer.

5. The device for detecting the dynamic stability of air film under ultrasonic vibration conditions according to claim 1, characterized in that: The resonant frequency range of the ultrasonic excitation transducer is 20kHz-100kHz.

6. The device for detecting the dynamic stability of air film under ultrasonic vibration conditions according to claim 1, characterized in that: The testing carrier also includes an air stop plate and a front cover. The front cover and the air stop plate are respectively fixedly attached to the upper and lower end faces of the air bearing. The front cover and the air stop plate are respectively provided with a first clearance hole and a second clearance hole that cooperate with the working shaft. A working convex ring is provided on the outer periphery of the upper end of the working shaft. The working convex ring is disposed in the first clearance hole and cooperates with the upper end face of the air bearing.

7. A method for detecting the dynamic stability of an air film under ultrasonic vibration conditions, implemented based on the device for detecting the dynamic stability of an air film under ultrasonic vibration conditions as described in any one of claims 1-6, characterized in that, Includes the following steps: Step S1: Preset the ultrasonic excitation frequency detection group parameters for multiple ultrasonic excitation transducers; Step S2: Start the ultrasonic excitation transducer. According to the parameters of each ultrasonic excitation frequency detection group, the ultrasonic excitation transducer outputs ultrasonic vibration consistent with the set parameters. The ultrasonic vibration is transmitted to the working shaft through the front end of the ultrasonic excitation transducer. Step S3: In each ultrasonic excitation frequency detection group, the vibration data acquisition device continuously acquires the raw vibration data of the working shaft for a specified time and transmits the raw vibration data to the controller in real time. Step S4: The signal processing unit of the controller analyzes the raw vibration data received from each ultrasonic excitation frequency detection group, extracts the vibration frequency and vibration amplitude, maps the vibration amplitude to the time axis, obtains the time domain signal, draws the time domain waveform based on the time domain signal, evaluates the stability of the air film based on the time domain waveform, and identifies the abnormal characteristics of the air film. Step S5: Convert the time-domain signal into a frequency-domain signal to generate a vibration spectrum. Based on the abnormal characteristics, focus on analyzing the spectral peaks with prominent amplitudes in the corresponding spectrum, locate the abrupt change points of the spectral characteristics, and determine the critical excitation conditions for gas film instability.

8. The method for detecting the dynamic stability of an air film under ultrasonic vibration conditions according to claim 7, characterized in that: Step S1 specifically includes: To connect the air bearing to the high-pressure air supply system, adjust the air supply pressure to the preset stable value, and complete the static support construction after the air film is formed and stabilized. The signal output terminals of the first and second vibration detectors are synchronously connected to the signal processing unit of the controller, and the sampling frequency that meets the requirements of ultrasonic frequency band acquisition is set to complete the zero-point calibration and synchronous trigger setting of the detection system. Multiple typical ultrasonic processing frequency bands are selected as reference excitation frequencies, and multiple typical processing amplitudes are selected as reference amplitudes. Multiple sets of ultrasonic excitation frequency detection parameters are preset based on the reference excitation frequencies and reference amplitudes.

9. The method for detecting the dynamic stability of an air film under ultrasonic vibration conditions according to claim 7, characterized in that: Step S4 specifically includes: The controller's signal processing unit first preprocesses the raw vibration data, then maps the vibration amplitude to the time axis to obtain the time domain signal and plots the time domain waveform. Key time-domain feature parameters, including vibration peak value, RMS value, root mean square value, and kurtosis, are extracted based on the time-domain waveform. Observe the stationarity of the time-domain waveform to determine the variation of vibration amplitude with excitation parameters; Identify anomalous features of the air film based on key time-domain characteristics, including abrupt shocks, waveform distortion, and amplitude divergence, and locate the time-domain range of the anomalous period.

10. The method for detecting the dynamic stability of an air film under ultrasonic vibration conditions according to claim 9, characterized in that: Step S5 specifically includes: Perform a fast Fourier transform on the time-domain signal to convert it into a frequency-domain signal and generate a vibration spectrum. Based on the abnormal time periods marked in step S4, focus on analyzing the spectral peaks with prominent amplitudes in the corresponding spectrum, and identify and extract the main oscillation frequency and its corresponding amplitude. By tracking the amplitude and harmonic component changes of characteristic frequencies under different excitation conditions, the frequency evolution law of air film vibration is analyzed. When a frequency sub-component or a sudden increase in high-frequency harmonic energy appears in the spectrum, it is determined to be the critical point of gas film instability, and the corresponding critical excitation frequency and critical excitation amplitude are extracted. Based on all critical point data, the stability-instability boundary curves of the air film were plotted to clarify the stable operating range of the air film under different working conditions.

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