JPH08226866A - Damage detection apparatus - Google Patents

Abstract

PURPOSE: To provide a damage detection apparatus which can easily and surely detect damages of an object having a fitted part on the inspection site. CONSTITUTION: A frequency band setter 8 is set at 950-500Hz, a measuring number setter 9 is set at [001] and a display selection switch 11 is positioned at [GRAPH]. A vibration sensor 4 is mounted to one stator coil which is then hit by a hammer 2. A natural frequency f0 and a damping ratio are calculated in a main body 7 of a measuring device based on a vibration force signal and a vibration signal from a load cell 3 and the vibration sensor 4. The natural frequency and damping ratio are stored in a memory 8, and at the same time displayed at a subject position on screen of a display device 10 as '.1'. While the number to be set by the measuring number setter 9 is sequentially changed, the sequence is repeated for every stator coil. Normal stator coils are shown at a lower right corner of the screen, while stator coils slackened by damages are displayed at an upper left corner of the screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting damage to an object to be detected, and more particularly to a damage detection device for detecting damage to an object having a fitting portion.

[0002]

2. Description of the Related Art For example, in a rotating electric machine such as a large motor or a generator, coils of a stator or a rotor may be damaged and loosen after 5 to 15 years from the manufacture. Conventionally, such looseness is detected by visual inspection or palpation at the time of regular inspection.

[0003]

However, since it is difficult to detect minute looseness by the conventional visual inspection and palpation as described above, it is difficult to reliably detect the damage that has occurred. .

Here, it is generally known that when an object having a fitting portion is loosened due to damage or the like at the fitting portion, the vibration characteristics change even if the looseness is small. There is. That is, due to the occurrence of slack, the natural frequency of the object decreases and the damping ratio increases. The natural frequency and the damping ratio can be calculated by measuring a transfer function (= vibration response / exciting force) indicating the vibration characteristic of the object and calculating the peak frequency of the transfer function and the sharpness of the peak. As a known technique relating to such a transfer function measuring method, for example, Japanese Patent Publication No.
A method has been proposed in which, as described in JP-A-79658, a signal obtained by the step excitation method is passed through a high-pass filter and then processed such as Fourier transform. In addition to this, many Fourier analyzers and the like using fast Fourier transform (FFT) are already on the market.

However, in the above known technique,
Although the natural frequency and damping ratio of each object can be calculated individually, no particular consideration is given to detecting damage to the object from the values of these natural frequencies and damping ratios. That is, for example, in the case of detecting the damage to the coil of the rotating electric machine by the above-described known technique, first, the transfer function is measured one by one on the spot using a Fourier analyzer or the like for each of the coils provided in the rotating electric machine. Then, the measured transfer function values are brought back and the natural frequency and the damping ratio of each coil are calculated from the transfer function. Further, the complicated work of comparing these with the values of the natural frequency / damping ratio of each coil in the past or with the values of the natural frequency / damping ratio of other coils is required. Therefore, it becomes difficult to easily detect the damage of the object on site.

An object of the present invention is to provide a damage detecting device capable of easily and reliably detecting damage to an object having a fitting portion on site.

[0007]

In order to achieve the above object, according to the present invention, a vibrating means for applying a vibrating force to an object to generate vibration, and a vibrating force of the vibrating means are measured. Then, a load cell that outputs a corresponding exciting force signal, a vibration sensor that measures the vibration generated in the object and outputs a corresponding vibrating signal, and the exciting force signal and the vibrating signal are input to these signals. Calculating means for calculating the values of the natural frequency and the damping ratio of the object based on the storage means, and storage means for inputting and storing the values of the natural frequency and the damping ratio of the plurality of objects calculated by the calculating means; Display means for displaying a list of natural frequency and damping ratio values of each object stored in the storage means as correlation data between the natural frequency and damping ratio and as data that can be compared with each other. Damage detection characterized by Location is provided.

Preferably, in the damage detection device,
The display means has a screen having two axes that are orthogonal to each other, and displays one of the two axes with the magnitude of the natural frequency and the other axis with the magnitude of the damping ratio. A damage detection device is provided.

Further preferably, in the damage detecting device, the calculating means divides a value of a vibration response by the vibration signal by a value of an exciting force by the exciting signal to obtain a transfer function, and a transfer function calculating means. , The natural frequency calculation means for calculating the natural frequency f _o from the peak of the waveform of the transfer function calculated by the transfer function calculation means, and the vibration level at the natural frequency f _o calculated by the natural frequency calculation means. The damping ratio ζ is calculated by calculating the frequencies f ₁ and f ₂ at which the vibration level becomes A _o / √2 when A _o, and dividing the difference between these two frequencies f ₁ and f ₂ by 2f _o. There is provided a damage detection device comprising a ratio calculation means.

More preferably, the damage detection apparatus further comprises frequency setting means for setting an arbitrary frequency range intended for calculation of a transfer function and outputting a corresponding command signal to the transfer function calculating means. A damage detecting apparatus is provided, wherein the function calculating means calculates a transfer function in a frequency range designated by a command signal from the frequency setting means.

Further, preferably, in the damage detection device, a number setting means for assigning a number corresponding to each object to the values of the natural frequency and the damping ratio of the plurality of objects stored in the storage means is further provided. The storage means stores the number assigned by the number setting means in association with the corresponding natural frequency and damping ratio of the object, and the display means stores the number and the corresponding number. There is provided a damage detection device characterized by displaying together with data of a target object.

[0012]

In the present invention configured as described above, for example, when an inspector applies vibration force to the object provided with the fitting portion by the vibration means to cause vibration, the vibration is generated by the vibration means. The vibrating force is measured by the load cell and the vibration of the object is measured by the vibration sensor, and the vibration force signal and the vibration signal are input to the calculation means. The calculation means calculates the values of the natural frequency and the damping ratio of the object based on these two signals. The calculated natural frequency and damping ratio are stored in the storage means. In this way, when a plurality of objects having fitting portions are successively excited by the vibrating means, the values of the natural frequency and the damping ratio of each object calculated by the calculating means are sequentially stored in the storing means. Is input and stored in. Then, the display means displays a list of the values of the natural frequency and the damping ratio of each object stored in the storage means as correlation data between the natural frequency and the damping ratio and as data that can be compared with each other. To be done. As a result, for example, when any one of the plurality of objects has a looseness due to damage, the data of the object has a lower natural frequency than that in the original state. Since the damping ratio should have increased, it is displayed as clearly different data in comparison with other objects in the natural frequency-damping ratio correlation data display state.
Therefore, the inspection worker can immediately identify that only this object is in an abnormal state.

Further, the display means has a screen having two axes orthogonal to each other, and one of the two axes has a natural frequency magnitude,
The other axis is displayed by the magnitude of the damping ratio. Thus, for example, when the natural frequency is on the horizontal axis and the damping ratio is on the vertical axis, the data of a normal object without looseness in the fitting part has a high natural frequency and a small damping ratio. The data of an object that is displayed in the lower corner and has a loose fitting portion has a low natural frequency and a large damping ratio, and thus is displayed in the upper left corner of the screen. Therefore, since the damaged object can be identified more clearly, even a person who does not have knowledge of vibration can easily diagnose the damage. Further, in the calculating means, the transfer function calculating means divides the value of the vibration response by the vibration signal by the value of the exciting force by the exciting signal to obtain the transfer function, and the natural frequency calculating means calculates the peak of the waveform of this transfer function. obtains the natural frequency f _o from the vibration level computed frequency f _1, f ₂ as the a _o / √2 when the vibration level in the natural frequency f _o and the a _o attenuation ratio calculating means, The difference between these two frequencies f ₁ and f ₂ is divided by 2f _o to obtain the damping ratio ζ. Thus, it is possible to realize a means for calculating the values of the natural frequency and the damping ratio of the object based on the exciting force signal and the vibration signal. In general, the transfer function usually includes many natural frequencies, but the frequency setting means sets an arbitrary frequency range intended for calculation of the transfer function, and the transfer function calculating means sets the frequency range from the frequency setting means. By calculating the transfer function in the frequency range instructed by the command signal, it is possible to prevent the natural frequency calculating means from unnecessarily calculating a large number of natural frequencies f _o, and the natural frequency f within the range actually required. Only _o can be calculated quickly. This also allows the damping ratio calculation means to smoothly
Can be calculated. Further, the number setting means gives a number corresponding to each object, the storage means stores the number and the value of the natural frequency and damping ratio of the corresponding object in association with each other, and the display means corresponds to the number and this. It is possible to further clarify the correspondence relationship between the data and the object by displaying the data of the object to be displayed together.

[0014]

Embodiments of the present invention will be described below with reference to FIGS. A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an external view showing the configuration of the damage detection device 100 according to this embodiment. In FIG. 1, a damage detection device 10
Reference numeral 0 denotes a measuring device body 7, a vibration sensor 4 attached to the measuring object 1 for measuring the vibration generated in the measuring object 1 and outputting a corresponding vibration signal, and an input terminal 6a of the measuring device body 7.
5a for connecting the vibration sensor 4 to the vibration sensor 4, a hammer 2 for applying a vibration force for applying vibration, and a vibration force of the hammer 2 attached to the tip of the hammer 2 is measured and a corresponding vibration signal is output. A load cell 3, a cable 5b connecting the input terminal 6b of the measuring device body 7 and the load cell 3, a frequency band setting device 8 for roughly specifying a range of natural frequencies to be detected, and a number corresponding to the measurement object 1. To the measurement data, a display 10 for displaying a list of the detection results of the measurement object 1 as correlation data between the natural frequency and the damping ratio, and a display method by the display 10 is selected. Display selection switch 11 and reset switch 12
And a power switch 13.

The calculation processing until the vibration signal and the exciting force signal input from the input terminals 6a and 6b into the measuring device body 7 are displayed on the display device 10 as the detection result is shown in FIG.
This will be described with reference to FIG. A block diagram showing the flow of signals in the measuring device body 7 is shown in FIG.

In FIG. 2, when the vibration sensor 4 is attached to the object to be measured 1 and the object to be measured 1 is hit with the hammer 2 to cause vibration, the vibration signal and the exciting force signal are transmitted through the cables 5a and 5b, respectively. It is inputted into the measuring instrument main body 7 from the input terminals 6a and 6b via the. In the measuring instrument body 7,
These two signals are amplified by the amplifier 14 and then sent to the A / D converter 16. The signal converted into the digital quantity by the A / D converter 16 is Fourier-transformed by the fast Fourier transformer 19 and converted into frequency domain data, that is, complex number data having a real number part and an imaginary number part. The result of the Fourier transform is sent to the calculator 17. The calculator 17 calculates the transfer function (= vibration response / excitation force) for each frequency using the value of the vibration response of the vibration signal and the value of the excitation force of the excitation signal. An example of the transfer function thus obtained is shown in FIG. FIG. 3 shows the magnitude (absolute value; dB) of the transfer function (= vibration response / excitation force) on the horizontal axis of frequency (Hz), and shows a large number of peaks (peak, That is, the natural frequency) and valleys are distributed. The upper part of FIG. 3 also shows the phase difference between the vibration response and the exciting force.

As shown in FIG. 3, the transfer function calculated from the measured data usually includes a large number of natural frequencies. At this time, the calculator 17 includes the frequency band setter 8
The command signal indicating the frequency range designated by is input, and the calculator 17 extracts and calculates only the transfer function within the commanded frequency range. The extracted transfer function usually has the form shown in FIG. In FIG. 4, the computing unit 17 detects the natural frequency f _o showing the peak of the transfer function taken out. Then, the computing unit 17 also detects the frequencies f ₁ and f ₂ indicating the vibration level (A _o / √2) of 1 / √2 of the vibration level (= A _o ) at the natural frequency f _o , The damping ratio ζ is calculated by calculating ζ = (f ₂ −f ₁ ) / 2f _o . Note that, as in FIG. 3, the upper diagram of FIG. 4 also shows the phase difference between the vibration response and the excitation force. That is, in the case where the vibration response is measured by the displacement as in the present embodiment, if the vibration is applied at a frequency lower than the natural frequency f _o, it vibrates in the same phase as the vibration force, but the natural frequency f
_o The phase delay of 90 ° from the exciting force is generated, even more exciting force at a somewhat higher frequency than the natural frequency f _o 18
A phase delay of 0 ° occurs (= opposite phase).

By the above procedure, the natural frequency f _o and the damping ratio ζ are obtained in the calculator 17. At this time, the measurement number designated by the measurement number setting unit 9 is input to the computing unit 17, and the obtained natural frequency f _o and the damping ratio ζ are stored in the memory 18 in association with this measurement number. .
As described above, the inspection worker can measure a plurality of measurement objects 1
Are sequentially excited to perform measurement, and the natural frequency f _o of each measurement object 1, the damping ratio ζ, and the measurement number are associated and sequentially stored in the memory 18. Then, all the data stored in the memory 18, that is, the measurement number of each measurement object 1, the natural frequency f _o , and the damping ratio ζ are displayed in a list on the display 10. The display method at this time is not only the method of displaying the natural frequency f _o and the magnitude of the damping ratio ζ with the horizontal axis and the vertical axis as shown in FIG. 1, but also the order of measurement number as shown in FIG. There is a method displayed as. This selection is performed by moving the display selection switch 11 to the "GRAPH" position or the "LIST" position. A signal corresponding to this selection is input to the display device 10 to switch the display method. In addition, the display 10 is stored in the memory 18.
All the data displayed in can be cleared by pressing the reset switch 12. The fast Fourier transformer 19 and the calculator 17 constitute a calculation means for calculating the natural frequency and the damping ratio according to the exciting force signal and the vibration signal.

Next, the operation and effect of this embodiment will be described by taking as an example the case of diagnosing the damage to the stator coil of a rotary electric machine. 6 and 7 show cross sections of the stator coil of the rotating electric machine. Generally, in a rotating electric machine, the stator coil 21 covered with the thin insulating layer 20 has a structure (see FIG. 6) fitted in the groove of the stator core 22, or the fitted portion is further pressed by the wedge 23. It has a structure (see FIG. 7). In such a structure, when looseness progresses in the fitting portion between the stator coil 21 and the groove of the stator core 22, the insulating layer 20 is peeled off due to friction to generate discharge, and finally the performance of the stator coil 21 and the stator core 22 is reduced. May deteriorate and have a significant adverse effect on the drive of the motor. Therefore, it is very important to detect and repair the looseness at an early stage. Less than,
A procedure in which an inspection worker detects damage to the stator coil 21 using the damage detection device 100 of this embodiment will be described in detail.

Generally, the stator core 22 of a rotary electric machine usually has several tens or more grooves, and the stator coil 21 is fitted in each groove. And the inspection worker
The natural frequency f _o and the damping ratio ζ will be measured for all the stator coils 21 using the detection apparatus 100 of the present embodiment. That is, the power switch 13 is turned on, and the frequency band setter 8 is set to, for example, "UPPER".
After setting 0 Hz "LOWER" to 500 Hz, setting the number to "001" with the measurement number setting device 9, and setting the display selection switch 11 to the "GRAPH" position, first,
The vibration sensor 4 is attached to one stator coil 21 (or the wedge 23) and the hammer 2 strikes it. Then, based on the exciting force signal and the vibration signal from the load cell 3 and the vibration sensor 4, the values of the natural frequency f _o and the damping ratio ζ are calculated in the measuring device main body 7 by the procedure described above and stored in the memory 8. . At the same time, it is displayed at a corresponding position on the screen of the display 10 such as “• 1” (see FIG. 1).
), And thereby the correspondence between the measurement object 1 and its data is clarified. At this time, the frequency range designated by the frequency band setter 8 is too wide, and a plurality of natural frequencies (for example, three f _o1 , f _o2 , and f _o3 3 are included in the range).
, The arithmetic unit 17 divides the specified frequency range into frequency ranges of appropriate widths including the respective natural frequencies (for example, a certain range including f _o1 , a range including f _o2 is included). A certain range, a certain range including _fo3 , is divided into three parts, and the damping ratios ζ ₁ , ζ ₂ , ζ ₃ corresponding to each are calculated. Then, any one of these three data is selected and stored in the memory 18, and at the same time, one ".
1 "is displayed. This one selection method may be a maximum value, a minimum value, or a value closest to a predetermined value among a plurality of natural frequencies, and the calculator 17 may make such a selection in advance. Operate.

The first stator coil 2 as described above
When the data display for 1 is finished, next, the number of the measurement number setting device 9 is changed to “002”, the vibration sensor 4 is attached to the next stator coil 21 (or wedge 23), and the hammer 2 is struck. Similarly, for example, “· 2” is displayed at the corresponding position. By repeating this procedure for all the stator coils 21 to be measured, the natural frequency f _o of all the stator coils 21.
And the value of the damping ratio ζ is displayed as a list on the screen of the display 10 as, for example, “· (measurement number)”.

At this time, among all of the measured stator coils 21, the normal stator coil 21 has a relatively high natural frequency f _{o and a} relatively small damping ratio, so that the lower right corner of the screen of the display 10 is shown. Is displayed in. FIG. 1 shows such cases as measurement numbers 1, 2, 3, 6, 7, 8, 12, 13, 1.
4, 15, 16 are attached. On the other hand, since the natural frequency f _o is lower damping ratio than stator coil 21 that loosening has occurred normally due to damage is increased, it is displayed in the upper left corner of the screen of the display device 10. FIG. 1 shows such a case by attaching measurement numbers 4, 5, 9, 10, and 11, for example.

In such a display, the measurement numbers 4,5,
Since the data of the stator coils 21 of 9, 10, and 11 are displayed as clearly different data as compared with the other stator coils 21, the inspection worker must check that the stator coils 21 are loose. The abnormal state can be immediately identified. Therefore, it is possible to easily detect the occurrence of damage in the field. At this time, since it is possible to detect a minute looseness, which has been difficult to detect by conventional visual inspection and palpation, it is possible to reliably prevent the occurrence of damage. Further, in addition to this, it is possible to easily find in advance the signs that the stator coil 21 is loosened due to damage, and even if the stator coil 21 has cracks, the presence of the cracks can be easily identified.
It can also be repaired before the 1 is damaged. Therefore, it is possible to prevent large damage due to breakage. Further, as described above, only the damaged stator coil 21 is displayed on the upper left of the screen, so that even a person who does not have knowledge of vibration can easily diagnose the damage. Further, since the frequency band setter 8 sets the frequency range for which the transfer function is intended to be calculated, only the natural frequency f _{o in} the really necessary range is rapidly calculated, and the damping ratio ζ is smoothly and quickly calculated. It can be calculated.

In the first embodiment, the display device 10 displays the magnitude of the damping ratio ζ on the ordinate and the magnitude of the natural frequency f _{o on} the abscissa, but the present invention is not limited to this. Not a thing. That is, conversely, the magnitude of the damping ratio ζ may be represented on the horizontal axis, and the magnitude of the natural frequency f _o may be represented on the vertical axis. Further, the display is not limited to the display using the two orthogonal axes, and displays other than this are represented by the correlation between the natural frequency f _o and the damping ratio ζ, and can be compared between the measurement objects 1. If Similar effects are obtained in these cases. In the first embodiment, when the frequency range designated by the frequency band setting unit 8 is too wide and a plurality of natural frequencies are detected by the computing unit 17, the computing unit 17 automatically selects one of them. I was supposed to choose, but it is not limited to this. For example, if the specified frequency range is too wide, a message saying "too wide to detect one natural frequency" is displayed, prompting the inspector to reset the frequency range, and A configuration may be adopted in which this procedure is repeated until detection is possible, and the same effect is obtained in this case as well. Further, in the first embodiment, as an example of the object having the fitting portion, the stator coil 21 of the rotating electric machine is used.
However, the present invention is not limited to this. In addition, the natural frequency f _o and the damping ratio
The damage detector 100 of the present embodiment can be applied to any structure as long as it can be identified as a normal one in which the values of and change without being damaged, and similar effects can be obtained in these cases. Further, in the first embodiment, the hammer 2 is used as the means for vibrating the measuring object 1, but the present invention is not limited to this, and a normal vibration exciter may be used. Also in this case, the same effect is obtained.

A second embodiment of the present invention will be described with reference to FIGS. The present embodiment is an embodiment in which the calculation methods of the natural frequency and the damping ratio are different. The same members and functions as those of the first embodiment are designated by the same reference numerals. The damage detecting apparatus according to the present embodiment differs from the damage detecting apparatus 100 according to the first embodiment mainly in that the load cell 3 that measures the exciting force of the hammer 2 and outputs a corresponding exciting force signal, and the measuring instrument body. Input terminal 6 of 7
This is due to the omission of the cable 5b that connects b and the load cell 3 and the internal function of the measuring device main body 207.
FIG. 8 is a block diagram showing the flow of signals in the measuring instrument body 207. FIG. 8 is a diagram corresponding to FIG. 2 in the first embodiment.

In FIG. 8, when the vibration sensor 4 is attached to the measuring object 1 and the hammer 2 strikes the measuring object 1 to cause vibration (= free vibration), a vibration signal is input via the cable 5a. It is input from the terminal 6a into the measuring device main body 207. In the measuring device main body 207, the vibration signal is amplified by the amplifier 14 and then sent to the bandpass filter 215. Since the vibration signal other than the measurement object 1 is superimposed on the vibration signal at this time, the band-pass filter 21
In 5, the components other than the natural frequency of the measuring object 1 are removed in advance. At this time, a command signal indicating the frequency range designated by the frequency band setting unit 8 is input to the bandpass filter 215, and the bandpass filter 215 removes components other than the commanded frequency range. The vibration signal after passing through the band-pass filter 215 has a damped sinusoidal vibration waveform as shown in FIG. That is, in FIG. 9, the vibration signals are time t ₁ , t ₂ , t ₃ , t ₄ , t ₅ , t ₆ , ..., T, t _{n + 1} , t _{n + 2.}
The maximum value of the amplitude at x ₁ , x ₂ , x ₃ , x ₄ , x ₅ , x ₆ , ..., x,
The waveform becomes x _{n + 1} , x _{n + 2} . By using a voltage-controlled filter as the filter, the cutoff frequency can be given as a voltage signal proportional to the frequency. In this way, the filter 215 attenuates the sinusoidal vibration waveform (=
The vibration signal having a damped free vibration waveform) is sent to the A / D converter 16 and converted into a digital value by a numerical value, and then sent to the computing unit 17.

The computing unit 17 carries out the following computations to obtain the natural frequency f _o and the damping ratio ζ. That is,
First, each period T ₁ , T ₂ , T ₃ , T ₄ , ... T _n of the damped sine vibration is _expressed as T ₁ = t ₃ −t ₁ T ₂ = t ₄ −t ₂ T ₃ = t ₅ −t ₃ T ₄ = determined by _{t 6 -t 4 ... T n =} t n + 2 -t n, the average T _m of a respective period, determined by _{T m = (T 1 + T} 2 + T 3 + T 4 + ...) / n. Then, the natural frequency f _o, since the reciprocal of the period can be calculated by f _o = 1 / T _m.

Next, the amplitude ratios of the adjacent maximum values are calculated as follows: r ₁ = x ₁ / x ₂ r ₂ = x ₂ / x ₃ r ₃ = x ₃ / x ₄ r ₄ = x ₄ / x ₅ r ₅ = the _{x 5 / x 6 ... r n} = x n / x n + 1 r n + 1 = x n + 1 / x n + 2 ... (1) that, these average values r _m, r _m = (R ₁ + r ₂ + r ₃ + r ₄ + r ₅ + r ₆ + ... + r _n + r _{n + 1} + r _{n + 2} ) / (n + 2) (2) The logarithmic decrement [delta] will be given in _{δ = log e r m ... (} 3).

Here, there is a relation of δ = 2πζ / √ (1-ζ ² ) ... (4) between the damping ratio ζ and the logarithmic damping rate δ, but the damping ratio ζ is usually larger than 1. since much smaller, (4) expression, δ ≒ 2πζ next, thus, by substituting the expression (3), ζ ≒ δ / 2π = log e r m / 2π = (log 10 r m / log 10 e) _{/ 2π = 0.3646 × log 10 r} m , and the therewith, it is possible to calculate the ζ damping ratio by (1) and (2) below.

The subsequent processing procedure is the same as that of the first embodiment. Other configurations and functions of the damage detection device are almost the same as those of the damage detection device 100 of the first embodiment.

Also in this embodiment, the same effect as in the first embodiment can be obtained.

In the first embodiment, the natural frequency f _o and the damping ratio ζ are found from the vibration response / excitation force, and in the second embodiment, the natural frequency f is calculated based on the time waveform of vibration. _{Although o} and the damping ratio ζ are obtained, the present invention is not limited to this, and the present invention can be applied to a case where the natural frequency f _o and the damping ratio ζ are obtained by a method based on frequency analysis, for example. That is, also in these cases, the same effect can be obtained by displaying a list of data on the display device 10.

[0033]

According to the present invention, after the excitation of a plurality of objects is completed, the display means lists as correlation data between the natural frequency and the damping ratio and as data which can be compared with each other. Since it is displayed, for example, if any one of the plurality of objects has a looseness due to damage, it will be displayed as clearly different data compared to other objects. Become. Therefore, the inspector can immediately identify that only this object is in an abnormal state, and can easily detect the occurrence of damage at the site. At this time, since it is possible to detect a minute looseness, which has been difficult to detect by conventional visual inspection and palpation, it is possible to reliably prevent the occurrence of damage. In addition to this, it is possible to easily find signs that looseness due to damage of the fitting part occurs in advance, and even if there is a crack in the object, for example, the existence of the crack can be easily identified, so that it can be repaired before the object is damaged can do. Therefore, it is possible to prevent large damage due to breakage.

Further, the display means has a screen provided with two axes orthogonal to each other, one of the two axes being the magnitude of the natural frequency,
Since the other axes are displayed according to the magnitude of the damping ratio, the damaged object can be more clearly identified, so that even a person who does not have knowledge of vibration can easily diagnose the damage. Furthermore, since the frequency setting means sets an arbitrary frequency range intended for calculation of the transfer function,
Only the natural frequency f _{o in} the really necessary range can be calculated quickly. Further, as a result, the damping ratio ζ can be smoothly calculated by the damping ratio calculating means. Further, since the number and the data of the object corresponding to the number are also displayed on the display means, the correspondence relationship between the data and the object can be further clarified.

[Brief description of drawings]

FIG. 1 is an external view showing a configuration of a damage detection device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing the flow of signals in the measuring instrument body shown in FIG.

FIG. 3 is a diagram showing an example of a transfer function obtained by the arithmetic unit shown in FIG.

FIG. 4 is a diagram showing an example of a transfer function extracted and calculated by the arithmetic unit shown in FIG.

5 is a diagram showing an example of another display method on the display shown in FIG.

FIG. 6 is a cross-sectional view of a stator coil of a rotary electric machine.

FIG. 7 is a cross-sectional view of a stator coil of a rotary electric machine.

FIG. 8 is a block diagram showing a signal flow in a measuring device main body included in a damage detector according to a second embodiment of the present invention.

9 is a diagram showing an example of a damped sine vibration waveform of a vibration signal after passing through the bandpass filter shown in FIG.

[Explanation of symbols]

1 measurement object (object) 2 hammer (vibrating means) 3 load cell 4 vibration sensor 7 measuring instrument body 8 frequency band setting device (frequency setting device) 9 measurement number setting device (number setting device) 10 display device 11 display selection switch 14 amplifier 16 A / D converter 17 arithmetic unit (transfer function calculating means, natural frequency calculating means, damping ratio calculating means) 18 memory (storage means) 19 fast Fourier transformer 20 insulating layer 21 stator coil 22 stator core 23 wedge 100 Damage detector 207 Measuring instrument 215 Band filter

Claims (5)

[Claims] 1. A vibrating means for applying a vibrating force to an object to generate vibration, a load cell for measuring the vibrating force of the vibrating means and outputting a corresponding vibrating force signal, and a load cell generated in the object. A vibration sensor that measures vibration and outputs a corresponding vibration signal, and a calculation unit that receives the exciting force signal and the vibration signal and calculates the natural frequency and the damping ratio of the object based on these signals. Storage means for inputting and storing the natural frequency and damping ratio values of the plurality of objects calculated by the calculating means, and the natural frequency and damping ratio values of each object stored in the storing means And a display unit for displaying a list as correlation data between the natural frequency and the damping ratio and as data that can be compared with each other. 2. The damage detection device according to claim 1, wherein
The display means has a screen having two axes that are orthogonal to each other, and displays one of the two axes with the magnitude of the natural frequency and the other axis with the magnitude of the damping ratio. Damage detection device. 3. The damage detection device according to claim 1, wherein
The calculating means divides a value of a vibration response by the vibration signal by a value of an exciting force by the exciting signal to obtain a transfer function, and a transfer function calculating means by the transfer function calculating means. a natural frequency calculating means for calculating a characteristic frequency f _o from the peak of the waveform, the vibration level is a _o / √ vibration levels in natural frequency f _o determined by the natural frequency calculating means when the a _o calculating the frequency f _1, f ₂ to be a 2, characterized in that it includes a two frequencies f _1, damping ratio calculating means the difference between f ₂ and is divided by 2f _o Request ζ damping ratio Damage detection device. 4. The damage detection device according to claim 3,
It further comprises frequency setting means for setting an arbitrary frequency range intended to calculate a transfer function and outputting a corresponding command signal to the transfer function calculating means, wherein the transfer function calculating means is a command signal from the frequency setting means. A damage detection device characterized by calculating a transfer function in the frequency range instructed by. 5. The damage detection device according to claim 1,
The storage means further comprises number setting means for assigning a number corresponding to each object to the values of the natural frequency and the damping ratio of the plurality of objects stored in the storage means. It is characterized in that the assigned number and the value of the natural frequency and the damping ratio of the object corresponding thereto are stored in association with each other, and the display means also displays the number and the data of the object corresponding thereto. Damage detection device.