CN104483118A - Rotor dynamic and static rub impact fault diagnosis method based on instantaneous frequency shaft centerline orbit - Google Patents

Abstract

The invention discloses a rotor dynamic and static rub impact fault diagnosis method based on an instantaneous frequency shaft centerline orbit. The method comprises the following steps: mounting two displacement sensors of which the included angle is 90 degrees on a vibration testing section; acquiring displacement vibration signals x(t) and y(t); performing EEMD (Ensemble Empirical Mode Decomposition) on the displacement vibration signals x(t) and y(t) respectively; performing spectral analysis on obtained mode components; respectively selecting IMF signal components IMFx(t) and IMFy(t) which are mainly power frequency components; calculating by using a direct orthogonal method to obtain instantaneous frequencies IFx(t) and IFy(t); subsequently decomposing single-component signals IMFx(t) and IMFy(t) into amplitude modulation signals and frequency modulation signals by means of normalization; synthesizing a shaft centerline orbit by using the calculated instantaneous frequencies IFx(t) and IFy(t) of one-time rotation frequency components in directions X and Y; identifying the running state of a rotor by using the shape of the shaft centerline orbit; extracting instantaneous fluctuation information of the rotating speed of the rotor by a bending vibration signal; synthesizing the instantaneous frequency shaft centerline orbit to realize effective diagnosis on rotor rub impact faults. The method disclosed by the invention has the advantages of improving the accuracy of the diagnosis on faults such as dynamic and static rub impact of the rotor and increasing the utilization rate of a bending vibration monitoring signal of the rotor.

Description

Based on the rotor impact and rub method for diagnosing faults of instantaneous frequency orbit of shaft center

Technical field

The present invention relates to rotary machine rotor fault diagnosis technology field, particularly based on the rotor impact and rub method for diagnosing faults of instantaneous frequency orbit of shaft center.

Background technology

The vibration that Rub-impact fault causes often shows non-linear, non-stationary feature, the very large failure mode of a class diagnosis difficulty, more existing signal analysis methods often can not accurately, intuitively to Rub-impact diagnosing malfunction, the diagnosis of particularly faint in early days Rubbing faults.

When rotor occur along the circumferential direction impact and rub fault time, rotor tangential by generation reverse friction power, the arm of force is rotor radius, thus be applied with a moment of torsion opposite to the direction of rotation to rotor, cause rotating shaft rotating speed abnormal momentary fluctuation, the i.e. abnormal torsional oscillation of rotor, due to the Flexural-Torsional Coupling Vibration characteristic of Rubbing faults, the abnormal torsional oscillation information of rotor can be embodied in the phase place of flexural vibrations signal.Contain failure message when rotor touches the faults such as mill in torsion vibration signal, torsional oscillation information is used, have very large benefit to diagnosis rotor fault, greatly can improve the accuracy of Rubbing faults diagnosis.Because the on-the-spot slewing run all does not install torsional vibration measurement device mostly, mean the twisting vibration information that directly cannot obtain slewing.By contrast, most Diagnosing System for Oil Pump has installed rotor radial vibration monitor system all, if extract rotor transient speed information (i.e. torsional oscillation information) and Appropriate application in addition from radial vibration, there is provided new thinking by the field diagnostic for impact and rub class fault, there is important engineering and economic benefit.

Summary of the invention

In order to overcome the shortcoming of above-mentioned prior art, the object of the present invention is to provide the rotor impact and rub method for diagnosing faults based on instantaneous frequency orbit of shaft center, by the momentary fluctuation information of flexural vibrations signal extraction rotor speed, and synthesize instantaneous frequency orbit of shaft center, thus realize the efficient diagnosis of Rub-impact fault.

For achieving the above object, the technical scheme that the present invention takes is:

Based on the rotor impact and rub method for diagnosing faults of instantaneous frequency orbit of shaft center, comprise the following steps:

Step one, the displacement transducer that two angles are 90 ° is installed in vibration-testing cross section, gather displacement vibration signal x (t) and y (t), in regulation rotor rotation process, the vibration measuring displacement transducer of first process is X-direction sensor, and clockwise another vibration measuring displacement transducer after half-twist is Y-direction sensor;

Step 2, carries out EEMD decomposition to displacement vibration signal x (t) of the X recorded, Y-direction with y (t) respectively, and adjustment EEMD resolution parameter, avoids the generation of mode mixing phenomenon;

Step 3, decomposes to X, Y-direction displacement vibration signal EEMD each mode component obtained and carries out spectrum analysis, pick out the IMF component of signal IMF based on power frequency component respectively _{x (t)}and IMF _{y (t)};

From EEMD, each IMF must meet following two conditions:

A. the extreme point number on whole signal is equal with zero crossing number or differ one at the most;

B. at any point, the coenvelope determined by all Local modulus maximas and be zero by the average of the determined lower envelope of all local minizing points;

Above-mentioned condition, ensure that signal IMF _{x (t)}and IMF _{y (t)}only comprise the vibration of a monotype respectively, thus obtain the instantaneous frequency of clear and definite physical significance;

Step 4, respectively to monotype component signal IMF _{x (t)}and IMF _{y (t)}direct orthogonalization method is used to calculate instantaneous frequency IF _{x (t)}and IF _{y (t)};

To simple component signal IMF _{x (t)}and IMF _{y (t)}amplitude modulation and FM signal is resolved into, that is, by normalization

Order: from the experience frequency modulation component definition orthogonal function of signal,

Therefore, the instantaneous phase of signal calculated by following formula and obtain:

Thus try to achieve signal IMF _{x (t)}instantaneous frequency is:

Step 5, doubly turns the instantaneous frequency IF of frequency component by the X calculated, Y-direction one _{x (t)}and IF _{x (t)}synthesis orbit of shaft center, by orbit of shaft center shape, identifies rotor operation state,

When rotor normally runs, one times of instantaneous frequency synthesis Chart of axes track turning frequency component is random distribution in certain area; When rotor generation impact and rub, power frequency component instantaneous frequency synthesis Chart of axes track presents figure of eight characteristic, and instantaneous frequency presents backward whirl phenomenon simultaneously.

Compared to prior art, the present invention has the following advantages:

A) essence of the present invention is the flexural vibrations signal extraction torsional oscillation information by rotor, and then realizes fault verification, improves the utilization factor of the flexural vibrations monitor signal of rotor.

B) compare existing Analysis of Torsional Vibration technology, the present invention just can complete torsion information extraction without the need to directly installing twisting vibration harvester additional, has saved hardware cost.

C) the rotor impact and rub method for diagnosing faults based on instantaneous frequency orbit of shaft center proposed by the invention can indicate the orientation that impact and rub occurs well, and can judge the order of severity of friction rotor fault according to the order of severity that the reversion of precession direction occurs.

Accompanying drawing explanation

Fig. 1 is embodiment rotor apparatus structural representation.

Fig. 2 is the sliding bearing that embodiment exists Rubbing faults.

Fig. 3 is the EEMD exploded view of original displacement vibration signal x (t) of embodiment.

Fig. 4 is the EEMD exploded view of original displacement vibration signal y (t) of embodiment.

Fig. 5 is the IMF obtained after embodiment X-direction signal EEMD decomposes _{x (t)}component signal.

Fig. 6 is the IMF obtained after embodiment Y-direction signal EEMD decomposes _{y (t)}component signal.

Fig. 7 is example I MF _{x (t)}the instantaneous frequency IF that component is tried to achieve by direct orthogonalization method _{x (t)}.

Fig. 8 is example I MF _{y (t)}the instantaneous frequency IF that component is tried to achieve by direct orthogonalization method _{y (t)}.

Fig. 9 is that embodiment is by IF _{x (t)}, IF _{y (t)}the instantaneous frequency orbit of shaft center of synthesis.

Figure 10 is the instantaneous frequency orbit of shaft center that this rotor apparatus uses the method to obtain when normally running.

Figure 11 is the filtering Chart of axes track that embodiment use EMD filtering orbit of shaft center method obtains.

Figure 12 is the Chart of axes track that this rotor apparatus uses EMD filtering orbit of shaft center method when normally running and obtains.

Embodiment

Describe the present invention below in conjunction with drawings and Examples.

Certain chemical plant carbon dioxide compressor machine set structure as shown in Figure 1, run unit 10# bearing place vibration quantitative change after a period of time large, tear machine overhauling open, to find on 10# sliding bearing that half-watt has and obviously touch polishing scratch mark, as shown in Figure 2, high pressure cylinder nominal operation rotating speed 13260rpm (221Hz).

Based on the rotor impact and rub method for diagnosing faults of instantaneous frequency orbit of shaft center, comprise the following steps:

Step one, the displacement transducer that two angles are 90 ° is installed in vibration-testing cross section, gather displacement vibration signal x (t) and the y (t) of rotor generation impact and rub and normal 10# bearing monitoring section when running, in regulation rotor rotation process, the vibration measuring displacement transducer of first process is X-direction sensor, and clockwise another vibration measuring displacement transducer after half-twist is Y-direction sensor;

Step 2, to 10# bearing X when touching mill, Y-direction displacement vibration data carry out EEMD decomposition, wherein x (t), y (t) represent X, Y-direction original signal, adjustment EEMD resolution parameter, avoid the generation of mode mixing phenomenon, decomposition result is as shown in Figure 3 and Figure 4;

Step 3, decomposes to X, Y-direction displacement vibration signal EEMD each mode component obtained and carries out spectrum analysis, determines that X, Y-direction vibration signal EEMD decompose IMF2 in each mode component obtained and be mainly one times and turn frequency component, i.e. IMF _{x (t)}and IMF _{y (t)}, as shown in Figure 5 and Figure 6;

Step 4, respectively to monotype component signal IMF _{x (t)}and IMF _{y (t)}direct orthogonalization method is used to calculate instantaneous frequency IF _{x (t)}and IF _{y (t)}, as shown in Figure 7 and Figure 8;

Step 5, doubly turns the instantaneous frequency IF of frequency component by the X calculated, Y-direction one _{x (t)}and IF _{x (t)}synthesis orbit of shaft center, obtain Chart of axes track, as shown in Figure 9, can find, instantaneous frequency Chart of axes track presents figure of eight characteristic, and occurs in Chart of axes track that mill position consistency is touched with actual in precession direction backward position (top),

When sliding bearing and rotor are without impact and rub fault, gather 10# bearing X, Y-direction displacement vibration signal in identical measuring point, same sample frequency, according to step above, same analysis is carried out to 10# bearing X, Y-direction displacement vibration data.

With reference to Figure 10, Figure 10 be rotor when normally running by 10# bearing X, Y-direction displacement vibration signal EEMD decomposes a times of obtaining and turns the instantaneous frequency Chart of axes track that frequency component solves the instantaneous frequency synthesis obtained, can find out when rotor normally runs, one times of instantaneous frequency synthesis Chart of axes track turning frequency component presents random distribution in certain area.

With reference to Figure 11 and Figure 12, Figure 11 and Figure 12 be respectively rotor generation Rubbing faults and normal when running by 10# bearing X, Y-direction displacement vibration signal EEMD decomposes the one times of Chart of axes track turning frequency component and synthesize obtained, when can find out rotor generation Rubbing faults, IMF2 (power frequency component) synthesizes orbit of shaft center and occurs obviously distortion, but only rely on this difference, the method of there is no confirms as rotor generation Rubbing faults, especially when rotor occur slight touch mill time, it is possible and not obvious on one times of impact turning the orbit of shaft center of frequency component synthesis, in conjunction with proposed instantaneous frequency Chart of axes track, can make a definite diagnosis further.

Above content is in conjunction with concrete preferred implementation further description made for the present invention; can not assert that the specific embodiment of the present invention is only limitted to this; for general technical staff of the technical field of the invention; without departing from the inventive concept of the premise; some simple deduction or replace can also be made, all should be considered as belonging to the present invention by submitted to claims determination scope of patent protection.

Claims (1)

1., based on the rotor impact and rub method for diagnosing faults of instantaneous frequency orbit of shaft center, it is characterized in that, comprise the following steps:

Step one, the displacement transducer that two angles are 90 ° is installed in vibration-testing cross section, gather displacement vibration signal x (t) and y (t), in regulation rotor rotation process, the vibration measuring displacement transducer of first process is X-direction sensor, and clockwise another vibration measuring displacement transducer after half-twist is Y-direction sensor;

Step 2, carries out EEMD decomposition to displacement vibration signal x (t) of the X recorded, Y-direction with y (t) respectively, and adjustment EEMD resolution parameter, avoids the generation of mode mixing phenomenon;

Step 3, decomposes to X, Y-direction displacement vibration signal EEMD each mode component obtained and carries out spectrum analysis, pick out the IMF component of signal IMF based on power frequency component respectively _{x (t)}and IMF _{y (t)};

From EEMD, each IMF must meet following two conditions:

A. the extreme point number on whole signal is equal with zero crossing number or differ one at the most;

B. at any point, the coenvelope determined by all Local modulus maximas and be zero by the average of the determined lower envelope of all local minizing points;

Above-mentioned condition, ensure that signal IMF _{x (t)}and IMF _{y (t)}only comprise the vibration of a monotype respectively, thus obtain the instantaneous frequency of clear and definite physical significance;

Step 4, respectively to monotype component signal IMF _{x (t)}and IMF _{y (t)}direct orthogonalization method is used to calculate instantaneous frequency IF _{x (t)}and IF _{y (t)};

To simple component signal IMF _{x (t)}and IMF _{y (t)}amplitude modulation and FM signal is resolved into, that is, by normalization

Order: from the experience frequency modulation component definition orthogonal function of signal,

Therefore, the instantaneous phase of signal calculated by following formula and obtain:

Thus try to achieve signal IMF _{x (t)}instantaneous frequency is:

Step 5, doubly turns the instantaneous frequency IF of frequency component by the X calculated, Y-direction one _{x (t)}and IF _{x (t)}synthesis orbit of shaft center, by orbit of shaft center shape, identifies rotor operation state,

When rotor normally runs, one times of instantaneous frequency synthesis Chart of axes track turning frequency component is random distribution in a rotary speed area; When rotor generation impact and rub, power frequency component instantaneous frequency synthesis Chart of axes track presents figure of eight characteristic, and instantaneous frequency presents backward whirl phenomenon simultaneously.