CN113484001B - Method for testing differential vibration between connecting parts - Google Patents
Method for testing differential vibration between connecting parts Download PDFInfo
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- CN113484001B CN113484001B CN202110741793.2A CN202110741793A CN113484001B CN 113484001 B CN113484001 B CN 113484001B CN 202110741793 A CN202110741793 A CN 202110741793A CN 113484001 B CN113484001 B CN 113484001B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M13/00—Testing of machine parts
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H17/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves, not provided for in the preceding groups
Abstract
The invention discloses a method for testing differential vibration between connecting parts, and relates to the technical field of vibration testing. The testing method comprises the steps that vibration time domain waveform data of a first connecting part and a second connecting part in the same direction are respectively obtained through a vibration tester, the time domain waveform data are converted into frequency doubling components through Fourier transformation, the vibration amplitude and the phase of each frequency doubling component are obtained, main vibration frequency components of the first connecting part and the second connecting part are respectively found out under each frequency doubling component, and the vibration amplitude of the first connecting part and the corresponding phase of the first connecting part, the vibration amplitude of the second connecting part and the corresponding phase of the second connecting part under the main vibration frequency components are found out; and carrying out vector subtraction operation to obtain a vector difference. The test method fully considers the amplitude and the phase of each frequency multiplication, so that the differential vibration result is more accurate.
Description
Technical Field
The invention relates to the technical field of vibration testing, in particular to a method for testing differential vibration between connecting parts.
Background
Detecting differential vibration between the connected components is a simple and effective method of checking the tightness of the connection of the connected components in a dynamic manner. The differential vibration refers to the magnitude of the difference in vibration between two adjacent connecting components, and the differential vibration value itself indicates that the two adjacent connecting components are subjected to relative displacement under dynamic conditions, and such a slight displacement will significantly reduce the connecting rigidity of the components, thereby causing large vibration. Therefore, in field vibration test analysis, the magnitude of differential vibration between the connecting parts is often required to be tested so as to know the strength of the rigidity of the connection.
The existing method for testing differential vibration mainly adopts a vibration dial gauge to respectively test the amplitude values of the vibration passband of two connecting parts in the same direction, then calculates the difference value to obtain the magnitude value of the differential vibration, and respectively tests the vibration amplitude value X of the connecting part A and the connecting part B in the vertical direction as shown in figure 1 A 、X B Then, the differential vibration Δ ═ X thereof is calculated A -X B L. The test method is simple and convenient, and only a small vibration test meter is adopted for testing, but the test method only considers the difference of the total vibration value between the connecting part A and the connecting part B, and does not consider the vibration angle and frequency. If the connecting part A and the connecting part B vibrate in a frequency doubling mode in the vertical direction, the amplitudes are the same, and the vibration angles are different by 180 degrees, the differential vibration calculated by the method is 0, and in fact, obvious relative motion exists between the connecting part A and the connecting part B, which indicates that the connecting part A and the connecting part B are not fastened and have poor connecting rigidity, and the equipment can vibrate greatly.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method for testing the differential vibration between connecting parts. The test method fully considers the amplitude and the phase of each frequency multiplication, so that the differential vibration result is more accurate.
In order to achieve the purpose, the invention adopts the following technical scheme: a method for testing differential vibration between connecting parts specifically comprises the following steps:
(1) respectively acquiring vibration time domain waveform data of the first connecting part and the second connecting part in the same direction through a vibration tester;
(2) respectively obtained in step (1)The vibration time domain waveform data of the first connecting part and the second connecting part are converted into I frequency multiplication components through Fourier transformation, simple harmonic time domain waveforms of the frequency multiplication components are obtained, and vibration amplitude values X of the frequency multiplication components of the first connecting part are recorded respectively i And the vibration amplitude Y of each frequency multiplication component of the second connecting part i Wherein I represents an index of the frequency multiplication component I;
(3) respectively calculating the difference between the peak time point of the simple harmonic time domain waveform of each frequency multiplication component of the first connecting part and the second connecting part and the zero pulse time point of the corresponding key phase channel waveform data, and then converting the difference into an angle to obtain the phase alpha of each frequency multiplication component of the first connecting part i Phase beta of each frequency multiplication component of the second connecting member i ；
(4) Respectively finding out main vibration frequency components of a first connecting part and a second connecting part under each frequency multiplication component, and finding out a vibration amplitude X of the first connecting part and a corresponding phase alpha thereof, a vibration amplitude Y of the second connecting part and a corresponding phase beta thereof under the main vibration frequency components; and carrying out vector subtraction operation to obtain a vector difference E.
Further, the same direction is a horizontal direction or a vertical direction.
Further, the fourier transform process specifically includes:
wherein t is time, i is an imaginary unit, F (t) is vibration time domain waveform data of the first connecting part or the second connecting part, ω is a frequency value of the frequency multiplication component, and F (ω) is a vibration amplitude of the frequency multiplication component.
Further, the specific process of obtaining the vector difference E is as follows:
further, when the distance between the measuring points on the first connecting part and the second connecting part is less than 100mm, the vector difference is less than 2 μm.
Furthermore, when the first connecting part and the second connecting part are connected in a sliding mode, the vector difference is smaller than 5 mu m.
Further, when the insulating pad is present between the first connection member and the second connection member, the vector difference is less than 7 μm.
Compared with the prior art, the invention has the following beneficial effects: the differential vibration testing method provided by the invention fully considers the amplitude and phase of each frequency multiplication, can effectively test the real differential vibration size between two connecting parts, and further evaluates whether the two parts are uniformly connected, so that the vibration reason can be more accurately judged in the vibration analysis processing. The differential vibration method can be applied to vibration analysis of various mechanical equipment on site.
Drawings
FIG. 1 is a diagram of a prior art method of testing differential vibration;
fig. 2 is a diagram of a vibration waveform of the first connecting member a in the horizontal direction;
fig. 3 is a vibration waveform diagram of the second connection member B in the horizontal direction.
Detailed Description
The invention provides a method for testing differential vibration between connecting parts, which specifically comprises the following steps:
(1) respectively acquiring vibration time domain waveform data of the first connecting part and the second connecting part in the same direction through a vibration tester; because the vibration has directionality, the difference of vibration time domain waveform data in different directions is large, the contrast exists only when the vibration in the same direction is detected, and the differential vibration can reflect the connection fastening condition between the first connecting part and the second connecting part, so that the same direction is the horizontal direction or the vertical direction;
(2) because the vibration time domain waveform data are decomposed into frequency multiplication components through Fourier transform, the excitation force types of the vibration time domain waveform data under the same frequency multiplication component are the same, and the vibration time domain waveform data have stronger contrast, the vibration time domain waveform data of the first connecting part and the vibration time domain waveform data of the second connecting part, which are acquired in the step (1), are subjected to Fourier transform respectively based on the fact that the vibration time domain waveform data are the same in excitation force type and have stronger contrastConverting into I frequency multiplication components to obtain simple harmonic time domain waveform of each frequency multiplication component, and recording vibration amplitude X of each frequency multiplication component of the first connecting component respectively i And the vibration amplitude Y of each frequency multiplication component of the second connecting part i Wherein I represents an index of the frequency multiplication component I;
the Fourier transform process in the invention is specifically as follows:
wherein t is time, i is an imaginary unit, F (t) is vibration time domain waveform data of the first connecting part or the second connecting part, ω is a frequency value of the frequency multiplication component, and F (ω) is a vibration amplitude of the frequency multiplication component.
(3) The vibration is vector and has directivity, and if only the vibration amplitude of each frequency multiplication component is considered and the phase is not considered, the directivity of the vibration cannot be considered when calculating the differential vibration, so that the accurate numerical value of the differential vibration cannot be calculated. In the invention, the peak time point of the simple harmonic time domain waveform of each frequency multiplication component of the first connecting part and the second connecting part and the zero pulse time point of the corresponding key phase channel waveform data are subjected to difference calculation and then converted into angles to obtain the phase alpha of each frequency multiplication component of the first connecting part i Phase beta of each frequency multiplication component of the second connecting member i ；
(4) Respectively finding out main vibration frequency components of a first connecting part and a second connecting part under each frequency multiplication component, and finding out a vibration amplitude X of the first connecting part and a corresponding phase alpha thereof, a vibration amplitude Y of the second connecting part and a corresponding phase beta thereof under the main vibration frequency components; and carrying out vector subtraction operation to obtain a vector difference E:
the vector difference E in the method for testing the differential vibration between the connecting parts fully considers the numerical property and the directionality of the vibration in the calculation process, and the calculation result can truly reflect the real and accurate vibration difference condition between the first connecting part and the second connecting part and can accurately reflect the connection fastening condition between the first connecting part and the second connecting part.
In the method for testing the differential vibration between the connecting parts, when the distance between measuring points on the first connecting part and the second connecting part is less than 100mm, the vector difference is less than 2 mu m; when the first connecting part and the second connecting part are in sliding connection, the vector difference is less than 5 mu m; when an insulating pad is arranged between the first connecting part and the second connecting part, the vector difference is less than 7 mu m. When the difference vibration of the first connecting part and the second connecting part is obviously larger than the numerical values, the connection rigidity of the bearing seat is judged to be insufficient, and the larger the difference vibration is, the more serious the fault is.
Examples
As shown in fig. 2, which is a waveform diagram of vibration of the first connection part a in the horizontal direction, the first connection part a has a vibration pass frequency value of 46.5 μm in the horizontal direction; fig. 3 is a diagram of a vibration waveform of the second connection member B in the horizontal direction, the vibration pass frequency value of the second connection member B in the horizontal direction being 50.5 μm; the differential vibration value obtained by differential vibration calculation in the prior art is as follows: 50.5-46.5 ═ 4 μm, i.e., the differential vibration values of the first connecting member a and the second connecting member B were within the acceptable range.
However, by adopting the method for testing the differential vibration between the connecting parts, the frequency doubling component of the first connecting part A under the main vibration frequency is 42.2 mu m, and the phase is 133 degrees; the frequency doubling component of the second connecting part B is 46.3 mu m at the main vibration frequency, and the phase is 278 degrees; the vector difference obtained by the method of the invention is as follows:
obviously fail to be qualified. Although the vibration amplitudes of the first connecting part A and the second connecting part B are relatively close, the phases of the first connecting part A and the second connecting part B are basically opposite, so that obvious anisotropic vibration exists, the connection and fastening conditions of the first connecting part A and the second connecting part B are poor, and the testing method fully considers the amplitude and the phase of each frequency multiplication, so that the differential vibration result is more accurate.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention.
Claims (6)
1. A method for testing differential vibration between connecting parts is characterized by comprising the following steps:
(1) respectively acquiring vibration time domain waveform data of the first connecting part and the second connecting part in the same direction through a vibration tester;
(2) fourier transform is carried out on the vibration time domain waveform data of the first connecting part and the second connecting part obtained in the step (1) to convert the vibration time domain waveform data into I frequency multiplication components, simple harmonic time domain waveforms of the frequency multiplication components are obtained, and vibration amplitude values X of the frequency multiplication components of the first connecting part are recorded respectively i And the vibration amplitude Y of each frequency multiplication component of the second connecting part i Wherein I represents an index of the frequency multiplied component I;
(3) respectively calculating the difference between the peak time point of the simple harmonic time domain waveform of each frequency multiplication component of the first connecting part and the second connecting part and the zero pulse time point of the corresponding key phase channel waveform data, and then converting the difference into an angle to obtain the phase alpha of each frequency multiplication component of the first connecting part i Phase beta of each frequency multiplication component of the second connecting member i ；
(4) Respectively finding out main vibration frequency components of a first connecting part and a second connecting part under each frequency multiplication component, and finding out a vibration amplitude X of the first connecting part and a corresponding phase alpha thereof, a vibration amplitude Y of the second connecting part and a corresponding phase beta thereof under the main vibration frequency components; and carrying out vector subtraction operation to obtain a vector difference E, wherein the calculation process of the vector difference E specifically comprises the following steps:
2. the method for testing differential vibration between joined members according to claim 1, wherein said same direction is a horizontal direction or a vertical direction.
3. The method for testing the differential vibration between the connecting parts according to claim 1, wherein the fourier transform process is specifically:
wherein t is time, i is an imaginary unit, F (t) is vibration time domain waveform data of the first connecting part or the second connecting part, ω is a frequency value of the frequency multiplication component, and F (ω) is a vibration amplitude of the frequency multiplication component.
4. The method for testing differential vibration between joined members according to claim 1, wherein the vector difference is less than 2 μm when the distance between the test points on the first joined member and the second joined member is less than 100 mm.
5. The method for testing differential vibration between coupled components of claim 1, wherein the vector difference is less than 5 μm when the first and second coupled components are slidably coupled.
6. The method for testing differential vibration between connection members according to claim 1, wherein the vector difference is less than 7 μm when an insulating pad is present between the first connection member and the second connection member.
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| US4607529A (en) * | 1984-03-21 | 1986-08-26 | John Morey | Vibration analysis |
| JP2768058B2 (en) * | 1991-07-02 | 1998-06-25 | 株式会社日立製作所 | Vibration test device for structure, vibration test method, and vibration response analysis device |
| CN102012263B (en) * | 2010-11-11 | 2012-07-25 | 华北电力大学 | Method for identifying turbine unit rotor vibration in-phase component stability in real time |
| CN104200118A (en) * | 2014-09-15 | 2014-12-10 | 吉林大学 | Automatic balancing machine vibration signal processing method |
| CN110907031A (en) * | 2019-12-04 | 2020-03-24 | 江苏方天电力技术有限公司 | Visual monitoring method for vibration variation of phase modulator based on data statistical analysis |
| CN112082720A (en) * | 2020-09-04 | 2020-12-15 | 江苏方天电力技术有限公司 | Method for determining early warning value of vibration fault of fixed-speed rotating machine |
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