A method for modal testing of a high power density up-gearbox

Abstract

The application discloses a kind of modal testing methods of high power density speed increasing gearbox, including obtaining the exciting frequency of high power density speed increasing gearbox;After high power density speed increasing gearbox is assembled, the output bearing position of high power density speed increasing gearbox is knocked, and the vibration data at bearing position is obtained, vibration data is converted from time domain signal into frequency domain signal, and the vibration spectrum diagram at output bearing position is obtained;According to the spectral line amplitude of vibration spectrum diagram, the frequency value corresponding to peak spectral line is selected, that is, the modal frequency of high power density speed increasing gearbox;Modal frequency and exciting frequency whether there is coupling resonance point in the working speed range area.The application can accurately test the modal frequency of high power density speed increasing gearbox, can accurately obtain its modal frequency, and can effectively identify potential coupling resonance point, which is beneficial to avoid the coupling resonance of modal frequency and exciting frequency.

Description

Technical Field

[0001] This invention belongs to the field of gearbox vibration testing technology, and in particular relates to a modal testing method for a high power density speed-increasing gearbox. Background Technology

[0002] High-power-density speed-increasing gearboxes are single-stage gear transmission systems, comprising components such as the input shaft, input large gear, input shaft support bearing, output gear shaft, output shaft support bearing, and gearbox housing. Due to their high speed-increasing ratio and high rotational speed, the vibration amplitude requirements for high-power-density speed-increasing gearboxes are stringent. However, high-power-density speed-increasing gearboxes experience a variety of excitation forces, including gear meshing excitation force, unbalanced excitation force, bearing misalignment excitation force, and coupling misalignment excitation force. The excitation frequencies of these forces are easily coupled with the inherent modes of the high-power-density speed-increasing gearbox, causing severe vibration, i.e., resonance. To address the problem of rapid vibration in high-power-density speed-increasing gearboxes, the investigation typically focuses on the direction of the excitation force. Reducing the excitation force will lower the amplitude to within the design requirements under the damping effect of the system, but this cannot fundamentally prevent the coupling between the excitation frequency and the modal frequency, and the following technical defects still exist:

[0003] (1) At present, the design of gearbox housings generally adopts a large redundancy design, which has a large safety factor, but the equipment is bulky, resulting in material waste and high processing costs.

[0004] (2) Regarding the vibration problem of high power density speed-increasing gearboxes, existing high power density speed-increasing gearboxes generally do not perform modal frequency testing, so it is impossible to provide a comparison between modal frequency and excitation frequency, and it is impossible to find out the root cause of the fault.

[0005] (3) The problem of abnormal vibration is usually dealt with by reducing the excitation force. Under the damping effect of the system, the amplitude will be reduced to the design requirement range. However, the modal resonance investigation of the gearbox is ignored, and there is still a risk of resonance. Summary of the Invention

[0006] The purpose of this invention is to provide a modal testing method for a high-power-density speed-increasing gearbox. This invention can accurately test the modal frequencies of the high-power-density speed-increasing gearbox, accurately obtain its modal frequencies, and effectively identify potential coupling resonance points, which helps to avoid coupling resonance between the modal frequencies and the excitation frequency. To achieve the above objective, this invention adopts the following technical solution:

[0007] According to one aspect of the present invention, a modal testing method for a high power density speed-increasing gearbox is provided, the modal testing method comprising the following steps:

[0008] A high power density speed-increasing gearbox model was constructed, and the excitation frequency of the high power density speed-increasing gearbox was obtained based on the input shaft speed and the structural parameters of the gearbox.

[0009] After the high power density speed-increasing gearbox is assembled, the output bearing of the high power density speed-increasing gearbox is tapped to obtain vibration data at the bearing position. The vibration data is then transformed from a time domain signal to a frequency domain signal to obtain the vibration spectrum at the output bearing position.

[0010] The frequency value corresponding to the peak spectral line is selected based on the amplitude of the spectral line in the vibration spectrum diagram, which is the modal frequency of the high power density speed-up gearbox;

[0011] Within the operating speed range of the high power density speed-increasing gearbox, determine whether there is a coupling resonance point between the modal frequency and the excitation frequency. If there is no potential coupling resonance point, the design of the high power density speed-increasing gearbox meets the requirements. If there is a potential coupling resonance point, optimize the structural parameters and repeat the above steps until it is determined that there is no potential coupling resonance point.

[0012] In summary, the invention adopts the above-mentioned technical solution and has the following technical effects:

[0013] (1) The present invention can accurately test the modal frequency of a high power density speed-increasing gearbox, accurately obtain its modal frequency, and effectively identify potential coupling resonance points through Campbell diagram based on its excitation frequency. The modal frequency can be adjusted out of the excitation frequency range by adjusting the support stiffness, adjusting the weight, optimizing the local structure, etc., which is beneficial to avoid coupling resonance between the modal frequency and the excitation frequency.

[0014] (2) Based on the modal frequencies and excitation frequencies, the Campbell diagram is drawn to identify the potential coupling resonance points in the speed range. By adjusting the support stiffness, adjusting the weight, and optimizing the local structure, the modal frequencies can be adjusted out of the working range, thereby enabling lightweight design of the high power density speed-increasing gearbox. That is, weight reduction design is carried out under the premise of meeting the stiffness and strength requirements. By optimizing and adjusting the local structure through modal frequency testing, material and processing costs can be effectively reduced. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating a modal testing method for a high power density speed-increasing gearbox according to the present invention.

[0016] Figure 2 This is a schematic diagram of the peak spectral line selection in this invention;

[0017] Figure 3 This is a schematic diagram of the Campbell's diagram of the present invention;

[0018] Figure 4This is a model diagram of a modal testing system for a high power density speed-increasing gearbox according to the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are merely to provide the reader with a thorough understanding of one or more aspects of the invention, and these aspects of the invention can be achieved even without these specific details.

[0020] Combination Figure 1 This invention provides a modal testing method for a high power density speed-increasing gearbox, characterized in that the modal testing method includes the following steps:

[0021] Step 1: Construct a high-power-density speed-increasing gearbox model. Based on the input shaft speed and the gearbox's structural parameters, obtain the excitation frequency of the high-power-density speed-increasing gearbox. The fundamental frequency f is obtained from the input shaft speed. The excitation frequencies of the coupling, gears, bearings, and unbalanced mass are all positively correlated with the fundamental frequency f. n =A n ×f, where n=1,2,3…; A n This is the proportionality coefficient, which represents the ratio between the excitation frequency and the fundamental frequency of the rotational speed.

[0022] Step 2: After the high power density speed-increasing gearbox is assembled, tap the output bearing of the high power density speed-increasing gearbox to obtain vibration data at the bearing position. Transform the vibration data from a time domain signal to a frequency domain signal to obtain the vibration spectrum at the output bearing position.

[0023] Step 3: Select the frequency value corresponding to the peak spectral line based on the amplitude of the vibration spectrum; this is the modal frequency of the high power density speed-up gearbox. Select the spectral line with the maximum amplitude Vmax, label the spectral lines with an amplitude of 0.3 × Vmax, and record the corresponding frequency value. Figure 2 As shown, the process of selecting the frequency value corresponding to the peak spectral line is as follows: A two-dimensional amplitude-frequency coordinate graph is established with the vertical axis representing vibrational amplitude and the horizontal axis representing frequency. The graph is then scanned and compared to obtain the peak spectral line corresponding to the maximum amplitude. Its vibrational amplitude Vmax and frequency F1 are recorded. A horizontal line is drawn with 0.3 × Vmax as the amplitude limit. Amplitudes exceeding this limit are recorded for their frequencies. Figure 2 The frequencies F2, F3, F4 shown are used until frequency F is obtained. n (n = 1, 2, 3, ...), which represents the modal frequencies obtained from the test.

[0024] Step 4: Determine whether there is a coupling resonance point between the modal frequency and the excitation frequency within the operating speed range of the high power density speed-increasing gearbox. If there is no potential coupling resonance point, the design of the high power density speed-increasing gearbox meets the requirements.

[0025] Step 5: If there are potential coupling resonance points, optimize the structural parameters of the gearbox and repeat steps 1 to 4 until it is determined that there are no potential coupling resonance points. The optimization of the structural parameters of the gearbox includes adjusting and optimizing the stiffness and mass parameters.

[0026] In this invention, such as Figure 1 and Figure 3 As shown, the process of determining whether there is a resonance point between the modal frequency and the excitation frequency includes the following steps:

[0027] Step 21: Draw a two-dimensional coordinate system with the modal frequency of the high power density speed-increasing gearbox as the vertical axis and the operating speed as the horizontal axis;

[0028] Step 22: Plot the modal frequencies and excitation frequencies in a two-dimensional coordinate system. Using the operating speed range of the high power density speed-increasing gearbox (n1, n2), [0.8n1, n1], [n2, 1.2n2] as conditions, record the coupling resonance points of the modal frequencies and excitation frequencies within the operating speed range.

[0029] Step 23: Determine whether the coupling resonance point between the modal frequency and the excitation frequency is a potential coupling resonance point. If there is no potential coupling resonance point, the high power density speed-increasing gearbox design meets the requirements. In this invention, if there is a potential coupling resonance point between the modal frequency and the excitation frequency, the designed high power density speed-increasing gearbox model structure is optimized and adjusted, and then modal testing is performed until there is no potential coupling resonance point between the modal frequency and the excitation frequency.

[0030] In this invention, such as Figure 3 As shown, the optimization and adjustment of the designed high-power-density speed-increasing gearbox model structure includes adjusting the support stiffness, component weight, and local structure of the high-power-density speed-increasing gearbox, and adjusting the modal frequency outside the operating speed range; if there are no potential modal coupling resonance points within the operating speed range, then it meets the design requirements; if there are no coupling resonance points within (n1, n2), [0.8n1, n1], [n2, 1.2n2], and the modal frequency range is 0~100Hz, then there is no risk of resonance. Figure 1As shown, since the excitation frequency is related to the rotational speed, a Campbell's distribution diagram of the high-power-density speed-increasing gearbox is plotted. The horizontal axis represents the input shaft rotational speed, and the vertical axis represents the frequency. That is, the modal frequencies and excitation frequencies are plotted on a two-dimensional graph with the input rotational speed on the horizontal axis and the frequency value on the vertical axis. The modal frequencies are assumed to be fixed values ​​in this diagram, and the intersection points of the Campbell's diagram are the potential modal resonance points. Through modal frequency testing, the modal frequencies F1, F2...F... of the high-power-density speed-increasing gearbox are obtained. n-1 F n The excitation frequency is a harmonic of the input shaft rotational speed as the fundamental frequency, f1, f2, ..., f. n-1 f n (n=1,2,3···), within the operating speed range (n1,n2) of the high power density speed-increasing gearbox, there exist modal resonance points G1, G2···G m-1 Because the vibration energy of high-frequency excitation is relatively small, the system damping of a high-power-density speed-increasing gearbox can effectively extinguish the vibration and will not excite coupled resonance in the high-power-density speed-increasing gearbox. Generally, G... m (m=1,2,3···) not exceeding 100Hz. If there are no coupling resonance points within (n1,n2) and 0~100Hz, there is no risk of resonance. If coupling resonance points exist, the modal frequencies are adjusted according to the optimization methods in section 4 until there are no coupling resonance points within (n1,n2) and 0~100Hz; based on the operating speed range of the high power density speed-increasing gearbox, potential modal resonance points outside the operating speed range are eliminated. If there are modal resonance points within the operating speed range, methods such as adjusting support stiffness, adjusting weight, and optimizing local structures are used to adjust the modal frequencies out of the operating speed range; if there are no potential modal resonance points within the operating speed range, the design requirements are met; the calculation formula for the modal frequencies of the high power density speed-increasing gearbox satisfies:

[0031]

[0032] In the formula, f is the modal frequency in Hz; k is the stiffness in N / m; and m is the mass in kg. Therefore, optimizing the structural parameters of the gearbox mainly involves adjusting and optimizing the stiffness and mass parameters. Based on the modal frequency calculation formula, to increase the modal frequency, one can increase stiffness, decrease weight, or both; to decrease the modal frequency, one can decrease stiffness, increase weight, or both. Increasing or decreasing stiffness is achieved by adding or removing reinforcing ribs; increasing or decreasing weight is done without affecting the structural function. If there is a risk of coupling between the modal frequency and the excitation frequency, methods such as adjusting the support stiffness, adjusting the weight, and optimizing the local structure can be used to adjust the modality out of the excitation frequency range. Lightweight design can be implemented for high-power-density speed-increasing gearboxes to reduce material and processing costs while meeting strength and support stiffness requirements.

[0033] According to another aspect of the invention, such as Figure 1 and Figure 4 As shown, the present invention also provides a modal testing system for a high power density speed-increasing gearbox. The modal testing system includes an impact-knock module and a test platform for mounting a high power density speed-increasing gearbox model. The test platform includes a data acquisition module, a data transformation module, a feature extraction module, a coupling test module, and a data analysis and processing module. The impact-knock module is used to impact the output shaft bearing position of the high power density speed-increasing gearbox. The data acquisition module is used to acquire vibration data of the high power density speed-increasing gearbox at the output shaft bearing position. The data transformation module is used to transform the vibration data in the time domain into a vibration spectrum signal in the frequency domain. The feature extraction module is used to perform spectral amplitude separation and extraction on the vibration spectrum signal to determine the frequency value at the output shaft bearing position and obtain the modal frequencies of the high power density speed-increasing gearbox under the spectral amplitude distribution. The coupling test module is used to plot the excitation frequency and modal frequencies of the high power density speed-increasing gearbox using a Campbell plot to obtain the coupling resonance point under high-speed rotation of the high power density speed-increasing gearbox. The data analysis and processing module is used to analyze the coupling resonance point to determine whether it poses a potential resonance risk.

[0034] In this invention, the modal testing system further includes a parameter setting module. Since the coupling resonance point represents a potential resonance risk, the data analysis and processing module acquires the model parameters of the high-power-density speed-increasing gearbox and corrects them. The parameter setting module acquires the corrected model parameters and resets the modal testing parameters, performing modal testing on the high-power-density speed-increasing gearbox again until no resonance risk exists. The stiffness and mass (weight) of the high-power-density speed-increasing gearbox are readjusted and corrected, serving as the input shaft speed and gearbox structural parameters. The output shaft bearing of the high-power-density speed-increasing gearbox is struck again, and vibration data at the bearing location is acquired. The corrected vibration data is then subjected to modal frequency testing and analysis to determine if a coupling resonance point exists, thereby eliminating the resonance risk. In this invention, the gearbox is struck three times in each of the vertical, horizontal, and axial directions. The modal data acquisition module uses a vibration accelerometer to acquire vibration data in three directions: vertical, horizontal, and axial. Due to differences in support stiffness in these three directions, the modal frequencies will differ. The vibration data in each direction is converted from time to frequency domain to obtain a spectrum. The vibration accelerometer uses an IEPE piezoelectric sensor with a frequency testing range of 5–1000 Hz. The sensor is positioned at the output shaft bearing of the high-power-density speed-increasing gearbox in the vertical, horizontal, and axial directions. The data transformation module converts the time-domain signal acquired by the vibration accelerometer into a frequency-domain signal after Fourier transform, outputting the modal frequency test spectrum. The feature extraction module extracts data from the spectrum, and the coupled testing module performs analysis to identify any coupling resonance points between the modal frequencies and the excitation frequency.

[0035] The above description is only a preferred embodiment of the invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and these improvements and modifications should also be considered within the scope of protection of the invention.

Claims

1. A modal testing method for a high power density speed-increasing gearbox, characterized in that: The modal testing method includes the following steps: A high power density speed-increasing gearbox model was constructed, and the excitation frequency of the high power density speed-increasing gearbox was obtained based on the input shaft speed and the structural parameters of the gearbox. After the high power density speed-increasing gearbox is assembled, the output shaft bearing of the high power density speed-increasing gearbox is tapped three times in each of the three directions: vertical, horizontal and axial. Vibration data at the bearing position is obtained, and the vibration data is transformed from a time domain signal to a frequency domain signal to obtain the vibration spectrum diagram at the output bearing position. The frequency value corresponding to the peak spectral line is selected based on the amplitude of the spectral lines in the vibration spectrum diagram, which is the modal frequency of the high power density speed-increasing gearbox. The process of selecting the frequency value corresponding to the peak spectral line is as follows: a two-dimensional amplitude-frequency coordinate graph is established with vibration amplitude on the vertical axis and frequency on the horizontal axis. The magnitude of each amplitude is scanned and compared in the two-dimensional coordinate graph to obtain the peak spectral line corresponding to the maximum amplitude. Its vibration amplitude Vmax and the corresponding frequency F1 are recorded. A horizontal line is drawn with 0.3×Vmax as the amplitude limit. The frequency of any amplitude exceeding the limit is recorded until the frequency F1 is obtained. n That is, the modal frequencies obtained from the test; Within the operating speed range of the high power density speed-increasing gearbox, determine whether there is a coupling resonance point between the modal frequency and the excitation frequency. If there is no potential coupling resonance point, the design of the high power density speed-increasing gearbox meets the requirements. If there is a potential coupling resonance point, optimize the structural parameters and repeat the above steps until it is determined that there is no potential coupling resonance point. If a potential coupling resonance point exists between the modal frequency and the excitation frequency, the designed high-power-density speed-increasing gearbox model structure is optimized and adjusted, and then modal testing is performed until there is no potential coupling resonance point between the modal frequency and the excitation frequency. The optimization and adjustment of the designed high-power-density speed-increasing gearbox model structure includes adjusting the support stiffness, component weight, and local structure of the high-power-density speed-increasing gearbox, adjusting the modal frequency outside the operating speed range. If there is no potential modal coupling resonance point within the operating speed range, then it meets the design requirements; the calculation formula for the modal frequency of the high-power-density speed-increasing gearbox satisfies: ； In the formula f k is the modal frequency, in Hz; k is the stiffness, in N / m; m is the mass, in kg. The process of determining whether there is a resonance point between the modal frequency and the excitation frequency includes the following steps: A two-dimensional coordinate system is plotted with the frequency of the high-power-density speed-increasing gearbox as the vertical axis and the operating speed as the horizontal axis. Campbell diagrams of modal frequencies and excitation frequencies are plotted in a two-dimensional coordinate system. The coupling resonance points of modal frequencies and excitation frequencies within the operating speed range of the high power density speed-increasing gearbox are recorded under the conditions of (n1, n2), [0.8n1, n1], and [n2, 1.2n2]. Determine whether the coupling resonance point between the modal frequency and the excitation frequency is a potential coupling resonance point. If there is no potential coupling resonance point, the high power density speed-increasing gearbox design meets the requirements.

2. The modal testing method for a high power density speed-increasing gearbox according to claim 1, characterized in that: If there are no coupling resonance points in (n1, n2), [0.8n1, n1], [n2, 1.2n2], and the modal frequency is within 0 to 100 Hz, then there is no risk of resonance.

3. A modal testing system for a high power density speed-increasing gearbox, used to perform the modal testing method for a high power density speed-increasing gearbox as described in any one of claims 1-2, characterized in that: The modal testing system includes an impact testing module and a testing platform for mounting a high-power-density speed-increasing gearbox model. The testing platform includes a data acquisition module, a data transformation module, a feature extraction module, a coupling testing module, and a data analysis and processing module. The impact testing module impacts the output bearing location of the high-power-density speed-increasing gearbox. The data acquisition module acquires vibration data of the high-power-density speed-increasing gearbox at the output bearing location. The data transformation module transforms the vibration data in the time domain into a vibration spectrum signal in the frequency domain. The feature extraction module separates and extracts the spectral amplitude of the vibration spectrum signal to determine the vibration amplitude at each frequency at the output bearing location and obtain the modal frequencies of the high-power-density speed-increasing gearbox. The coupling testing module plots the excitation frequency and modal frequencies of the high-power-density speed-increasing gearbox using a Campbell's plot to obtain the coupling resonance points under high-speed rotation of the high-power-density speed-increasing gearbox. The data analysis and processing module analyzes the coupling resonance points to determine whether they pose a potential resonance risk.

4. The modal testing system for a high power density speed-increasing gearbox according to claim 3, characterized in that: The modal testing system also includes a parameter setting module. If the coupling resonance point is a potential resonance risk, the data analysis and processing module obtains the model parameters of the high power density speed-increasing gearbox and corrects the model parameters. The parameter setting module obtains the corrected model parameters and resets the modal testing parameters.

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