JP2021028618A - Sealing material deterioration diagnosis method and deterioration diagnosis device - Google Patents

Abstract

To provide a method and a device that non-destructively measure a deterioration state of a sealing material attached to a machine, an apparatus, a pipe or the like and diagnose the same with simple and high accuracy.SOLUTION: The method for diagnosing deterioration of a sealing material according to the present invention detects, by a vibration sensor installed at a structure, a vibration generated when the structure is vibrated with respect to the structure connecting a first member and a second member through the sealing material, extracts a frequency spectrum of a specific vibration mode via the sealing material from the detected vibration waveform, calculates an attenuation amount from the vibration waveform corresponding to the frequency spectrum, and diagnoses a deterioration state of the sealing material based on the attenuation amount.SELECTED DRAWING: Figure 1

Description

The present invention relates to a deterioration diagnosis method and a deterioration diagnosis device for a sealing material used for the purpose of preventing leakage of gas or liquid inside in a structure such as a machine, a device, or a pipe.

Sealing materials for airtightness or liquidtightness are used for equipment connection parts and pipe connection parts of equipment in which gas or liquid is sealed inside. For example, an oil-filled transformer has an insulating oil sealed inside, and a sealing material is used at the connection point between the transformer main body and the accessory so that the insulating oil does not leak.
A polymer material is mainly used as the material of the sealing material, and in particular, a sealing material mainly made of rubber is used. Since rubber is a polymer material, deterioration such as oxidative deterioration progresses with long-term use, and rubber elasticity decreases. Rubber elasticity refers to the property that rubber deformed by an external force instantly restores its original shape due to high internal stress, and exhibits sealing properties with the force that tries to restore it to its original shape. If the rubber elasticity decreases due to deterioration, the airtightness decreases and the possibility of internal fluid leakage increases. Therefore, it is necessary to check the deteriorated state of the sealing material and replace the sealing material at an appropriate time.

In the deterioration diagnosis of the sealing material, generally, the sealing material is removed from the equipment used, and the chemical composition, physical properties, etc. are measured. If the equipment is small and easy to disassemble, such as an oil rotary vacuum pump, the sealing material can be removed regularly and replaced if necessary, but the equipment cannot be stopped easily, such as electric power equipment. Equipment that is not easy to disassemble can only collect sealing material when it is removed or overhauled. For example, in order to evaluate the deterioration of the sealing material used for the oil-immersed transformer, it is necessary to remove the accessories from the transformer and collect the sealing material.
To do so, first disconnect the transformer from the power system and then drain the internal insulating oil with a pump truck. After degreasing, it takes a lot of labor and time to remove the bolts and separate the transformer body and the accessories while fishing the accessories with a crane car. Even if the sealing material can be removed from the device, the sealing material once removed from the device cannot be reused regardless of the deterioration state of the sealing material. Therefore, the sealing material may deteriorate while being attached to the device. It is desirable to be able to diagnose.

Several test methods for evaluating the internal state of a structure are disclosed, and among them, the vibration test is applied in various fields as a relatively easy evaluation method (Patent Documents 1 to 4 and Non-Patent Document 1). reference).
In the vibration test, the structure is vibrated (strike) with a hammer or the like, and the vibration generated by the vibration is detected by an acceleration sensor or the like. Since the vibration generated by the vibration reflects the state inside the structure, it can be applied to deterioration diagnosis if the vibration characteristics and deterioration can be related.

The technique described in Patent Document 1 hits a reference object whose shape, material, and characteristics have been determined in advance, and has a relationship between the resonance frequency and the attenuation coefficient of the vibration generated from the reference object. , The material discrimination region is made into a region, and there is a step of setting the deterioration inclination characteristic peculiar to the reference object with respect to the relationship between the resonance frequency and the attenuation coefficient as the reference in the region. Further, the technique described in Patent Document 1 includes a step of specifying the material of the object to be measured from the relationship between the measured resonance frequency and the attenuation coefficient of the object to be measured in the regioned material discrimination region, and the measurement. It has a step of specifying the reference deterioration inclination characteristic corresponding to the relationship between the resonance frequency and the attenuation coefficient of the measured object. Further, the technique described in Patent Document 1 has the crack amount of the object to be measured and the relationship of the replacement required area with respect to the deterioration inclination characteristic as described above. It is a method for diagnosing deterioration of an article, which comprises a step of calculating the life of an object to be measured.

The deterioration diagnostic apparatus described in Patent Document 1 is a material of a reference material with respect to the relationship between the resonance frequency and the attenuation coefficient of vibration generated from the reference material by hitting a reference material whose shape, material, and characteristics are determined in advance. , A database means for storing data on deterioration characteristics including crack amount and life, a striking means for striking the object to be measured, and measuring the resonance frequency and damping coefficient of vibration of the object to be measured generated by the striking. It has a vibration measuring means. The deterioration diagnostic apparatus described in Patent Document 1 determines the material, crack amount, and life of the measured object from the data of the database means corresponding to the relationship between the resonance frequency and the attenuation coefficient of the measured object measured as described above. It is characterized by having a deterioration calculation means for obtaining deterioration characteristics including the deterioration characteristics.

In the technique described in Patent Document 2, in a concrete structure having a portion having the same thickness, the sound portion of the concrete structure to be measured is vibrated in advance to measure the resonance frequency, and the reference resonance frequency spectrum of the sound portion is obtained. create. Next, another measuring unit is vibrated to measure the resonance frequency of the measuring unit, the resonance frequency spectrum of the measuring unit is created, and the created resonance frequency spectra are superposed to determine the degree of deviation between the two resonance frequency spectra. The degree of deterioration of the internal structure is determined by analysis.
According to the technique described in Patent Document 2, by analyzing the degree of complexity that is complicated compared to the spectrum of the sound part, or by analyzing the degree of blunting of the peak of the spectrum, the measurement point can be measured. The degree of softening of cement, cracks, release of reinforcing bars from concrete, etc. can be measured.

Further, the outline of the second invention described in Patent Document 2 is based on vibration in a sound portion by vibrating a sound portion of the concrete structure to be measured in advance in a concrete structure having a portion having substantially the same thickness. The reference resonance frequency of the mode is detected. Next, the value of the reference phase velocity is calculated from the reference resonance frequency, and another measuring unit is vibrated to detect the peak of the resonance frequency of the vibration in the vicinity of the reference resonance frequency. Then, the phase velocity value of the vibration is calculated from the resonance frequency of the measuring unit at the peak, the two phase velocity values are compared, and the difference value is analyzed to determine the degree of deterioration of the internal structure. According to the above second invention, the degree of deterioration of the internal structure of the reinforced concrete structure can be quantitatively determined.

The technique described in Patent Document 3 directly hits the shaft spring rubber, which is a vibration-proof member of a railroad vehicle, causes the shaft spring rubber to vibrate, and determines the deterioration state based on the vibration characteristics.
According to this technology, the vibration generated by the vibration of the shaft spring rubber is detected, the time change of the vibration acceleration of the new product and the used product, and the acceleration / excitation force are measured, and the measurement results of the new product and the used product are compared. Therefore, the deterioration status of the used product can be determined.
The guideline for determining that the used product has deteriorated is when the amplitude of the vibration acceleration of the used product becomes smaller than the amplitude of the new vibration acceleration over time, or when the period of the vibration acceleration of the used product is new vibration. If it is shorter than the acceleration cycle, the vibration acceleration / excitation force 1/3 octave band analysis result of the used product is compared with the new vibration acceleration / excitation force 1/3 octave band analysis result. Then, when the vibration acceleration / excitation force of the used product is shifted to the higher frequency side as a whole compared to the new vibration acceleration / excitation force, the vibration wave height value is comprehensively increased with respect to the increase in the usage period. When it increases, it is determined that the shaft spring rubber has deteriorated when the vibration level value increases as the period of use increases.

The technique described in Patent Document 4 vibrates one of two members fastened with a seal member sandwiched by a vibrating means, and responds to the vibration of the one member by the vibration. The vibration generated in the other member of the one member is detected by the vibration detecting means. The technique of Patent Document 4 uses the power spectrum of the vibration of the other member obtained by Fourier transforming the vibration signal of the other member detected by the vibration detecting means by the conversion means, and determines the quality of the sealing member. This is an inspection method for determining.
In this inspection method, the quality of the sealing member is improved by comparing the peak frequency of the vibration power spectrum of the other member and its gain output from the conversion means with the peak frequency of the reference vibration power spectrum and its gain. Is characterized by determining. Further, a region having a width wider than this point for both the peak frequency and the gain is set around the peak frequency of the reference vibration power spectrum and the gain point thereof, and the other member output from the conversion means. When the peak frequency of the power spectrum of the vibration and its gain deviate from the region, it is determined that the sealing member has an abnormality.

Non-Patent Document 1 describes a vibration damping characteristic test method for bending vibration of a free beam at both ends and a cantilever beam of a restraint type vibration damping steel plate (hereinafter, vibration damping steel plate) in which a resin film is sandwiched between two steel plates. Has been done. The vibration damping steel plate fixed by the predetermined holding method is vibrated using a hammer, an electromagnetic vibrator, and an impulse hammer, and in the generated damping free vibration waveform, the maximum values of the response displacements X ₁ , X ₂ , ... -Read X _{n , plot with X k + 1 on} the horizontal axis and X _k on the vertical axis, and obtain the loss coefficient (η) from the slope θ of the straight line connecting the points through the origin from the following equation (1).

Further, in Non-Patent Document 1, the frequency response curve obtained by excitation is obtained, and the i-order resonance frequency fi at an arbitrary resonance peak and the frequency at the point where the absolute value of the transfer function is 3 dB lower than the maximum value. A method _{of reading f i1} and f _i2 and obtaining the loss coefficient (η) from the following equation (2) is shown.

Japanese Unexamined Patent Publication No. 62-293151 Japanese Patent No. 3340702 Japanese Unexamined Patent Publication No. 2006-90811 Japanese Patent No. 3646551

JIS G0602 Vibration damping characteristics test method for vibration damping steel sheet

What is common to the above patent documents is the disclosure of a technique for hitting an object to be measured, measuring the vibration generated as a result, and evaluating the soundness of the object to be measured from changes in the obtained vibration waveform and resonance frequency spectrum. Is. In the prior art, quality is often judged by the difference from the reference data, but the part where the sealing material is used has various shapes for each object to be measured, and each structure has complicated vibration characteristics. Therefore, it is difficult to prepare a reference object for each measurement object.
Since the sealing material is used in a state of being sandwiched between a plurality of structures, its resonance frequency spectrum is extremely complicated because the resonance frequency of each structure and the resonance frequency generated by the contact between the structures are superimposed. It becomes a shape. Therefore, it is difficult to analyze the deterioration state only by measuring the resonance frequency spectrum as in the prior art.
Further, Patent Document 3 only evaluates the difference from a new product, and does not mention the quantitative evaluation. Although Patent Document 4 can determine the quality of a structure containing a sealing material, it has not yet quantitatively indicated the degree of deterioration of the sealing material.

The structure sandwiching the sealing material can be regarded as a vibration damping material, and if the loss coefficient of the structure is evaluated by the technique described in Non-Patent Document 1, it is considered that a change in the characteristics of the sealing material can be detected. Compared to the vibration damping steel plate specified in Patent Document 1, the structure sandwiching the sealing material has a complicated structure and has many vibration modes, so that it is difficult to directly apply the test method of Non-Patent Document 1. ..

Therefore, an object of the present invention is to provide a method for non-destructively measuring the deterioration state of a sealing material attached to a machine, an apparatus, a pipe, or the like, and diagnosing it easily and with high accuracy.

(1) In the method for diagnosing deterioration of a sealing material of the present invention, a structure in which a first member and a second member are connected via a sealing material is subjected to vibration generated when the structure is vibrated. It is detected by a vibration sensor installed on the body, a frequency spectrum of a specific vibration mode via the sealing material is extracted from the detected vibration waveform, a damping amount is calculated from the vibration waveform corresponding to the frequency spectrum, and the damping amount is calculated. It is characterized in that the deterioration state of the sealing material is diagnosed based on the above.

(2) According to the present invention, in the sealing material deterioration diagnosis method according to (1), when the vibration is detected by the vibration sensor, a plurality of vibration positions or vibration directions are changed with respect to the structure. When the vibration waveforms are observed and the vibration waveforms include a vibration waveform having a frequency spectrum in which a single vibration mode is excited, the damping amount is calculated from this vibration waveform and based on the damping amount. It is characterized in that the deterioration state of the sealing material is diagnosed.
(3) The present invention is a vibration waveform in which the vibration waveform measured in the sealing material deterioration diagnosis method according to (1) is a mixture of a vibration component that decays quickly and a vibration component that decays slowly, and a plurality of vibration modes. When is an overlapping vibration waveform, the required frequency spectrum is extracted from this vibration waveform, the vibration waveform of the vibration mode of only a specific peak is obtained from this frequency spectrum by inverse calculation, and the amount of attenuation is obtained from this vibration waveform. It is characterized in that the deterioration state of the sealing material is diagnosed based on this damping amount.

(4) In the present invention, in the sealing material deterioration diagnosis method according to any one of (1) to (3), the amount of attenuation of the sealing material when it is new is measured, and after a certain period of time, the sealing material is again sealed. It is characterized in that the attenuation amount of the material is measured to obtain the attenuation amount ratio, and the deterioration of the sealing material is diagnosed according to the deterioration evaluation standard based on the attenuation amount ratio determined in advance.
(5) In the present invention, in the sealing material deterioration diagnosis method according to any one of (1) to (4), the attenuation amount when the compression set is 100% is defined as the use limit value (limit attenuation amount). It is characterized in that deterioration of the sealing material is diagnosed according to a deterioration evaluation standard in which a certain amount of margin is set for the critical attenuation amount.
(6) According to the present invention, in the sealing material deterioration diagnosis method according to (3), when the vibration waveform of the vibration mode of only a specific peak is obtained by an inverse calculation, any of the inverse FFT conversion, wavelet conversion, and Hibert-Huang conversion. It is characterized by using.

(7) In the sealing material deterioration diagnostic apparatus of the present invention, a vibration waveform due to vibration generated when the structure is vibrated with respect to a structure connecting the first member and the second member via the sealing material. Is received from the vibration sensor, the frequency spectrum of the specific vibration mode via the sealing material is extracted from the vibration waveform, and the calculation means for calculating the attenuation amount from the vibration waveform corresponding to the frequency spectrum and the attenuation amount are used. It is characterized by providing a deterioration status determining means for determining the deterioration status of the sealing material based on the above.

(8) In the sealing material deterioration diagnostic apparatus of the present invention, a plurality of vibration waveforms are observed by the vibration sensor by changing the vibration position or the vibration direction with respect to the structure, and a single vibration waveform is included in these vibration waveforms. When a vibration waveform having a frequency spectrum in which one vibration mode is excited is included, it is preferable that the calculation means has a function of calculating the amount of attenuation from the vibration waveform.
(9) In the sealing material deterioration diagnostic apparatus of the present invention, the measured vibration waveform is a vibration waveform in which a vibration component that attenuates quickly and a vibration component that attenuates slowly are mixed, and is a vibration waveform in which a plurality of vibration modes overlap. In this case, the calculation means is provided with a function of extracting a necessary frequency spectrum from this vibration waveform, obtaining a vibration waveform of a vibration mode of only a specific peak from this frequency spectrum by an inverse calculation, and obtaining an amount of attenuation from this vibration waveform. Is preferable.

(10) In the sealing material deterioration diagnostic apparatus of the present invention, the attenuation amount of the sealing material when new is stored in the deterioration status determining means, and the attenuation amount of the sealing material measured after a certain period of time and the new product are measured. It is preferable that the deterioration status determining means is provided with a function of comparing the attenuation ratio with the attenuation amount of the above and diagnosing the deterioration of the sealing material according to the deterioration evaluation standard based on the attenuation ratio determined in advance.
(11) In the sealing material deterioration diagnostic apparatus of the present invention, the attenuation amount when the compression set is 100% is recorded in the deterioration status determination means as the use limit value (limit attenuation amount), and a constant amount is recorded in the limit attenuation amount. It is preferable to have a function of diagnosing deterioration of the sealing material according to a deterioration evaluation standard that defines a margin.
(12) In the sealing material deterioration diagnostic apparatus of the present invention, any of inverse FFT conversion, wavelet conversion, and Hibert-Huang conversion is applied as a function of obtaining the vibration waveform of the vibration mode of only a specific peak by inverse calculation. Is preferable.

According to the present invention, the vibration waveform of a single vibration mode generated when the structure is vibrated by changing the vibrating position or direction is measured by a vibration sensor and attenuated from the frequency spectrum obtained from this vibration mode. The amount can be calculated, and the deterioration state of the sealing material can be grasped based on this damping amount.
Therefore, according to the present invention, it is possible to diagnose and grasp the deterioration status of the sealing material attached to the machine, device, piping, etc. in a non-destructive and simple process, and externally diagnose the necessity of replacing the sealing material. Can be determined by.

In addition, a plurality of vibration modes are superimposed on the vibration waveform measured by the vibration sensor, and even if the vibration waveform is complicated, the vibration mode having only a specific peak is extracted from the frequency spectrum, and the vibration waveform is calculated by inverse calculation. By obtaining the above, the amount of damping can be calculated, and the deterioration state of the sealing material can be grasped based on the amount of damping.

When diagnosing deterioration of the sealing material as described above, the damping amount is compared with the damping amount of the sealing material when it is new, and the damping amount ratio with the damping amount measured after a lapse of a predetermined time is obtained, and based on a predetermined evaluation standard. , Can diagnose and grasp the deterioration status of the sealing material.
In addition, if the damping amount when the compression set rate is 100% is defined as the limit damping amount and the deterioration evaluation standard that defines a certain amount of margin from the limit damping amount is set, the damping amount when new is unknown. Deterioration diagnosis can be performed even with a sealing material.

When the above-mentioned inverse calculation is performed, the vibration waveform can be obtained from the frequency spectrum having a specific peak by using any of the inverse FFT transform, wavelet transform, and Hibert-Huang transform, and the deterioration diagnosis of the sealing material can be performed.

It is a figure for demonstrating the vibration test performed when carrying out the deterioration diagnosis method of the sealing material which concerns on one Embodiment of this invention, and (A) is the state which vibrated by the hammer to the object which installed the acceleration sensor. (B) is an explanatory diagram showing a state in which an acceleration sensor is installed on an object having a sealing material and the object is vibrated with a hammer, and (C) is a vibration according to the vibration test shown in (A). A graph showing the vibration waveform measured by the sensor, (D) is a graph showing the vibration waveform measured by the vibration sensor by the vibration test shown in (B). An example of a structure in which a pipe flange and a butterfly valve are connected via a sealing material is shown, and (A) is a perspective view of the structure as viewed from one side in order to explain a first vibration test, (B). Is a perspective view of the structure viewed from the other side in order to explain the second vibration test. It is explanatory drawing which shows an example of the case where the state of the vibration of a butterfly valve obtained by the vibration analysis is visualized. The frequency spectrum obtained by Fourier transforming the vibration waveform obtained by the vibration test is shown, and (A) is obtained from an example of the vibration waveform obtained by the first vibration test shown in FIG. 2 (A). The graph showing the frequency spectrum (B) is a graph showing the frequency spectrum obtained from an example of the vibration waveform obtained by the second vibration test shown in FIG. 2 (B). The relationship between the vibration waveform obtained by the vibration test and the amount of attenuation is shown. (A) is a graph showing an example of the vibration waveform, and (B) is the vibration waveform shown in (A) displayed in decibels (dB) for attenuation. It is a graph which shows the result of having calculated the quantity. The graph which shows the relationship between the compression set rate of a sealing material, and the damping amount ratio of a sealing material. A graph showing the frequency characteristics that each hammer can act on when the tip attached to the tip of the hammer is replaced and vibrated. A graph showing a frequency spectrum obtained by Fourier transforming the vibration waveform obtained by each hammer when the tip attached to the tip of the hammer is replaced and vibrated. It is a flowchart which shows an example of the deterioration diagnosis method of the sealing material which concerns on one Embodiment of this invention. The block diagram which shows an example of the deterioration diagnosis apparatus used when carrying out the deterioration diagnosis method of the seal material. Perspective view showing the vibration position by hammer and the installation position of the vibration sensor for the flange bottle used to obtain the deterioration of the sealing material and the change of the damping amount for the purpose of associating the compression set rate with the vibration test result. .. It shows the process of selecting the target vibration mode and obtaining the attenuation ratio when multiple vibration modes are mixed by the vibration test. (A) shows the original vibration waveform measured by the vibration sensor in the vibration test. The graph shown, (B) is a graph showing a frequency spectrum obtained by Fourier transform from the original vibration waveform shown in (A), (C) is a graph showing a state in which only the target frequency spectrum is extracted, and (D) is extracted. It is a graph which shows the result of having obtained the vibration waveform by the inverse FFT from the frequency spectrum. FIG. 5 is a cross-sectional view showing an example of a vibration exciter suitable for use in the method for diagnosing deterioration of a sealing material according to the present invention. The operation of the vibration exciter shown in FIG. 13 is shown. FIG. 13A is a cross-sectional view showing an initial state, (B) is a cross-sectional view showing a state in which a knob is pulled, and (C) shows a state in which a hammer is projected. The cross-sectional view, (D) is a cross-sectional view showing a state returned to the initial state.

Hereinafter, an embodiment relating to the method for diagnosing deterioration of the sealing material according to the present invention will be described in detail. First, the principle of the diagnostic method by the vibration test adopted in the first embodiment will be described.
The vibration test is a test method in which an object 3 is vibrated (struck) by a hammer 1 as shown in FIG. 1A, and the resulting vibration is detected by a vibration sensor 2. The vibration characteristics generated by the vibration are determined by the structure of the object 3, and when the sealing material 4 is present inside the object 3 as shown in FIG. 1 (B), the elastic force of the sealing material 4 causes the vibration of the object 3 to vibrate. The change in the characteristics of the sealing material 4 can be detected based on the change in the characteristics.
It is preferable to use a hammer having a replaceable tip 1a at the tip of the hammer 1. A plurality of the chips 1a are prepared for each constituent material, and by changing the chips 1a, vibrations in different frequency bands can be performed. The relationship between the chip 1a and the frequency band will be described in detail later.

When the object 3 is a single metal plate as shown in FIG. 1 (A), the vibration acceleration (m / s ² ) measured by the vibration sensor 2 gradually becomes monotonous as shown in FIG. 1 (C). Although it is obtained as a decreasing type of vibration waveform, the waveform indicated by the vibration acceleration measured by the vibration sensor 2 in the presence of the sealing material 4 has an exponentially large attenuation ratio as shown in FIG. 1 (D). Observed as a vibration waveform. However, when the elastic force of the sealing material 4 changes, the vibration characteristics change, so that it is possible to grasp the change in the elastic force of the sealing material 4 from the change in the vibration characteristics.
That is, as deterioration progresses and the characteristics of the sealing material 4 change, the vibration characteristics also change accordingly. Therefore, according to this method, changes in the hardness of the sealing material 4 and deformation due to compression can be detected. It is considered possible to evaluate the deterioration of the sealing material without collecting the sealing material from the operating equipment.

Structures such as machines, devices, and pipes usually have a large number of natural vibration modes, and the frequencies of these modes vary depending on the material and shape of the structure. The frequency excited by the vibration is in line with the natural vibration mode of the structure, but which mode is excited varies depending on the vibration position, direction, and the like.
As a result of investigating the vibration mode of the structure including the sealing material, the present inventors have found that only a specific vibration mode can be excited if the vibration position and direction are set to appropriate positions.
For example, as shown in FIG. 2A, the butterfly valve 6 used in the oil-immersed transformer has a structure 9 in which the pipe flange 8 is connected to the front and rear of the butterfly valve 6 via a sealing material 7. Regarding this structure 9, when the flange surface is vibrated, the vibration mode in which the butterfly valve 6 and the pipe flange 8 move together is excited, while when only the side surface of the butterfly valve 6 is vibrated, the butterfly valve alone vibrates. Can be excited.

The vibration of the integrated structure 9 is not easily affected by the change in the characteristics of the sealing material 7, and is not suitable as a diagnostic index. On the other hand, if the vibration of the butterfly valve 6 alone is the vibration through the sealing material 7, the characteristic change of the sealing material 7 appears more remarkably. That is, by exciting only the natural vibration mode of a specific structure (single butterfly valve 6) among the vibration modes of the integrated structure 9 including the sealing material 7, the deterioration of the sealing material 7 can be deteriorated with high accuracy. It will be possible to detect it.
Even if it is not possible to excite only a specific vibration mode, if the natural frequency of the structure itself can be grasped in advance, only the specific frequency component should be extracted to reproduce the vibration waveform. Therefore, it is considered that the same evaluation becomes possible. Further, if the target frequency component is clear, it is considered that the evaluation can be performed excluding the unnecessary vibration mode by vibrating so that the exciting force is equal to or lower than the target frequency.

In the structure 9 in which the pipe flange 8 is connected via the sealing material 7 in the pipe through which the fluid flows, the sealing material 7 deteriorates due to long-term use, the sealing property deteriorates, and the sealing material 7 is used. There is a high possibility that internal fluid will leak from the joint. Deterioration of the sealing material 7 is generally evaluated by the compression set ratio expressed as the ratio of the permanent strain amount to the compression amount.

Therefore, in the present embodiment, the deterioration of the sealing material is defined by the compression set, and the deterioration of the sealing material can be diagnosed by associating the compression set with the vibration test result.

The sealing material in use is deformed by receiving compressive stress from the structure. If the sealing material is new, it will return to its original shape if the compressive stress is removed, but if the sealing material is deteriorated, the compression set will be reduced due to the decrease in thickness due to plastic deformation in the lateral direction and the increase in the amount of permanent strain. Is increasing. An increase in the compression set means a decrease in the elastic force of the sealing material, and a decrease in the elastic force acting on the structure changes the vibration characteristics of the structure.
The sealing material inside the structure also acts as a damping material, and by converting the generated vibration energy into heat energy, the vibration is dampened and suppressed. Therefore, the vibration generated by the vibration is damped by the vibration damping action of the sealing material. The damping action of the sealing material changes according to the elastic force of the sealing material.

That is, when the compression set rate increases due to deterioration of the sealing material, the elastic force of the sealing material decreases, fluid leakage is likely to occur, and the vibration suppressing effect of the sealing material also decreases. It is considered that deterioration diagnosis of the sealing material becomes possible by evaluating the damping characteristics of the generated vibration.
As a procedure for evaluating the damping characteristics of vibration, the vibration generated by the vibration to the structure including the sealing material is measured by an acceleration sensor or the like. At that time, it is preferable to perform the vibration at a position where only the natural vibration of the structure itself is excited.
Regarding the determination of the vibration position, it is possible to determine the most efficient measurement point by visualizing the state of vibration during vibration. Finite element method and experimental mode analysis can be used to visualize the state of vibration.

In this embodiment, a method of determining the excitation position by the experimental mode analysis will be described below.
In the experimental mode analysis, the shape of the target structure is defined on the coordinate axes, the frequency response function (transfer function) at each point is measured, and these structures resonate (from the phase and gain information). It is a method of visualizing the vibration mode form when (vibrates at a frequency that easily vibrates).
As an example, a method for determining the excitation position by experimental mode analysis of a butterfly valve that connects a tank body of an oil-immersed transformer to a radiator or the like will be described below. First, in the structure of the butterfly valve and the pipe flange, the coordinates are defined as shown in FIG. 2, and the measurement points are determined.
For the pipe flange 8, the boundary line of each cell is set as a dividing line so that the rectangular flange surface is divided into cells of 6 rows × 10 columns, and the upper surface and the lower surface of the pipe flange 8 are 6 rows × 2 columns. The boundary line of each cell is set as a dividing line so as to divide into cells, and the boundary line of each cell is set as a dividing line so as to divide both side surfaces of the pipe flange 8 into cells of 2 rows × 10 columns. For the butterfly valve 6, a dividing line is set so as to divide the upper surface and the lower surface into cells of 6 rows × 4 columns, and a dividing line is set so as to divide both side surfaces into cells of 4 rows × 10 columns. Then, the intersections of all these dividing lines are set as measurement points.

Further, the setting standard of the coordinate division shown in FIG. 2 is an example, and the division line is set so as to divide into smaller cells or larger cells than in the case shown in FIG. Is also good. However, if there are too many measurement points, it takes time to measure, and if there are too few measurement points, it becomes difficult to discover that a vibration mode peculiar to a specific structure is excited. Therefore, for example, 20 for the structure to be measured. It is desirable that the division can set about 50 measurement points. The number of divisions is not limited to this range when the structure is a large-scale structure, and may be further subdivided.
In FIG. 2, the thickness and length of the pipe 10 provided with the pipe flange 8 are abbreviated, and only the position of the pipe 10 is described, and these are integrated through the pipe flanges 8 and 8 and the butterfly valve 6. The description of the changed bolts and nuts is omitted.
Further, although omitted in FIG. 2, a transformer structure such as a transformer tank is connected to the other end side of the pipe 10 connected to one pipe flange 8, and the pipe connected to the other pipe flange 8. Other transformer structures such as radiators, bushings, and relay pipes are connected to the other end side of the 10. Therefore, in the structure 9 shown in FIG. 2, the other end side of one pipe 10 is restrained by the transformer structure to suppress vibration, and the other end side of the other pipe 10 is also restrained by the transformer structure. Vibration is suppressed.

The intersections of the dividing lines shown in FIGS. 2A and 2B are the measurement points, but it is not necessary to measure at all the measurement points, and the unmeasured points can be interpolated from the data of the surrounding measurement points.
As illustrated in FIGS. 2A and 2B, in the present embodiment, the measurement point on the upper right side when the surface is viewed from the front is defined as S1, the upper middle S2, the upper left S3, and the middle stage are S4 to 6. , The lower row is defined as S7-9. Similarly, the measurement points on the facing side were set to S10 to 18, the upper surface was set to S19 to 26, and the lower surface was set to S27 to 35. Since there is a handle of the butterfly valve 6 not shown in the middle stage of the upper surface, it is excluded from the measurement points. In the process of visualization described later, the handle is treated as having no handle, and the calculation is performed on the assumption that the shape is flat like the others.

Further, the structure 9 shown in FIG. 2A is a pipe made of a steel plate having a thickness of 25 mm and a height × width (170 × 170) mm at the end of a pipe (outer diameter: 103 mm, inner diameter 93 mm) made of a steel pipe. It has a pair of structures with flanges and a butterfly valve having a thickness of 50 mm and a height x width (170 x 170) mm. A bolt made of a nitrile butadiene rubber (NBR) rubber ring with a thickness of 6 mm and an outer diameter x inner diameter (143 mm x 125 mm) is inserted on both sides of this butterfly valve and penetrates the pipe flange and the outer frame of the butterfly valve. And the nuts screwed into these bolts are integrated to form the structure 9.

In the case of the structure 9 shown in FIGS. 2A and 2B, the following measurements were performed by defining the 36 measurement points described above.
If the flange surface is vibrated, the measurement point "S36" is vibrated with a hammer with the vibration sensor attached to the measurement point "S1" to acquire data. Next, the vibration sensor is moved to the measurement point “S2”, and the measurement point “S36” is vibrated with a hammer to acquire data. The measurement point “S36” is a measurement point on the right end side of the flange surface located on the right side of the pipe 10. In FIG. 2A, when the flange surface is divided into 5 division lines that divide the flange surface into 6 equal parts in the left-right direction and 9 division lines that divide the flange surface into 10 equal parts in the vertical direction, 5 from the left side of the flange surface. The intersection of the third dividing line and the fifth dividing line from the upper side of the flange surface is vibrated.
After that, the measurement points are moved in the same manner and vibrated with a hammer to perform sequential measurement, and data is acquired at all the defined measurement points. The vibration sensor used at this time is a three-axis vibration sensor for visualizing three-dimensional vibration.

An experimental mode analysis was performed using the above measurement data, and the state of the three-dimensional vibration of the structure 9 was visualized. If three-axis vibration sensors are installed at 36 measurement points and data is acquired for each measurement position, three-dimensional vibration can be measured for each position where the vibration sensor is installed. It is possible to visualize (animate the display) in what direction the butterfly valves 6 sandwiched between them are vibrating individually.

Regarding the structure 9 shown in FIG. 2 (A), when the vibration mode at a characteristic resonance frequency was visualized, in a relatively low frequency region (around 3 kHz), a rotational motion around the vertical axis, a vibration mode called yawing, was used. It turned out that there was. It was also found that the expansion / contraction vibration was superimposed on the yawing as the frequency increased, and the expansion / contraction vibration appeared more prominently in a relatively high frequency region (7 kHz or more).

In the structure 9 shown in FIG. 2A, the vibration caused by yawing of the structure 9 caused by the vibration of the flange surface is the vibration of the structure 9 itself, and is therefore not easily affected by the sealing material 7. On the other hand, since the expansion / contraction vibration observed in the high frequency region is the vibration mode of the butterfly valve 6 as a single structure, it is considered to be a vibration mode suitable for the evaluation of the sealing material 7.
Therefore, in order to more strongly excite the expansion / contraction vibration, which is the vibration mode of the butterfly valve 6 as a single structure, the side surface of the butterfly valve 6 and the measurement point “S14” shown in FIG. 2 (B) are vibrated. For the measurement, the measurement point "S14" is vibrated with the vibration sensor attached to the measurement point "S1" to acquire data. Next, the vibration sensor is moved to the measurement point “S2”, and the measurement point “S14” is vibrated to acquire data. Next, the measurement points are sequentially moved from S3 to S35 except for the measurement point "S14", and the measurement point "S14" is vibrated to acquire data.
Vibration and measurement are performed in sequence while moving the measurement points as described above, and data is acquired at all the defined measurement points. An experimental mode analysis was performed using this measurement data, and the state of vibration of the butterfly valve 6 and the pipe flanges 8 and 8 was visualized.
An example thereof is shown in FIG. In FIG. 3, it was found that the pipe flange 8 was vibration-suppressed by the transformer structures existing on both sides thereof, but the butterfly valve 6 vibrated strongly as one structure.

The method of visualizing the vibration of an object such as the structure 9 by displaying it in animation will be described below.
To express the vibration of the object surface, a finite number of coordinate points are set on the object surface, and the direction and magnitude of the displacement at each coordinate point are reproduced. Although the motion of each point is complicated, since it is a periodic motion, it can be represented by superposition of simple vibrations having different frequencies. Therefore, the vibration represented by the time axis of each point is Fourier transformed to obtain the amplitude for each frequency.
Next, for a specific frequency, what kind of relative phase difference each point oscillates is obtained. Specifically, it is necessary to obtain the phase difference between any two coordinate points, which is achieved by obtaining the transfer function.

The transfer function is a quantity that indicates how much amplitude and phase a certain point (point A) is vibrated with a force of a unit magnitude and a response is made at another point (point B). Therefore, one of the coordinate points is set as the vibration point, and vibration sensors are installed at all the remaining coordinate points to perform the vibration test. This transfer function has the property of Maxwell's reciprocity theorem, and the same transfer function can be obtained when the response is measured at point A by vibrating point B.
Therefore, all the response functions between each coordinate point can be obtained even though the measurement is not performed by installing the vibration sensor at the vibration point. It is also possible to obtain a response function between all coordinate points by performing a vibration test using one vibration sensor and sequentially moving the vibration sensor.
Similarly, it is possible to obtain all response functions by fixing the vibration sensor in one place and vibrating the remaining coordinate points in sequence, which makes it easy to install the sensor and hammers. The measurement method can be selected according to the ease of vibration.

Then, one of the coordinate points is set as a reference point, and the remaining coordinate points simply vibrate with a phase difference between the amplitude and the reference point at that point in accordance with the simple vibration of the reference point at a certain frequency. By using the commercially available software "ME'scope VES", which is a commercially available software, the vibration of the surface of the object can be displayed as an animation on the display screen of the personal computer running the analysis software. ..
FIG. 3 captures and animates the simple vibration of each measurement point with respect to the measurement points shown in FIGS. 2 (A) and 2 (B) with respect to the structure in which the butterfly valve is sandwiched between the flange plates, based on the above method. It is explanatory drawing which cuts out one screen of the display state.

The frequency spectrum of the vibration obtained by vibrating the flange surface “S36” in FIG. 4 (A) and Fourier transforming the vibration waveform measured at the measurement point “S5” by FFT (fast Fourier transform) is obtained. Shown in FIG. 4B, the frequency spectrum of vibration obtained by vibrating the measurement point “S14” of the butterfly valve 6 and Fourier transforming the vibration waveform measured at the measurement point “S5” by FFT is shown.

As shown in FIG. 4 (A), a plurality of resonance frequencies were observed in the excitation of the flange surface, but in the excitation of the side surface of the butterfly valve shown in FIG. 4 (B), only one resonance frequency was particularly strongly excited. The frequency spectrum was obtained. When the vibration mode at the resonance frequency was visualized, it was found to be the expansion / contraction vibration of the butterfly valve 6.
In the vibration of the side surface of the butterfly valve, the vibration such as yawing observed in the vibration of the flange surface was hardly excited. In the flange surface vibration, the natural vibration of the pipe flange 8, the natural vibration of the butterfly valve 6, and the natural vibration of the butterfly valve structure were superimposed to form a very complicated frequency characteristic, but in the side vibration of the butterfly valve 6, the butterfly Since the natural vibration of the valve is strongly excited, the vibration caused by others is relatively small, and simple frequency characteristics are obtained.

In this embodiment, since a substantially single frequency characteristic is obtained, it is possible to directly obtain the damping amount of the vibration from the vibration waveform obtained by the vibration.
When the vibration waveform shown in FIG. 5 (A) is obtained, the attenuation amount is calculated by converting the signal of the vibration waveform into a decibel display (logarithmic display of the vibration ratio) as shown in FIG. 5 (B).
Since the vibration decreases exponentially, when the decibel display is used as shown in Fig. 5 (B), the vibration waveform becomes a waveform that can draw a downward-sloping straight line connecting the peaks of each wave, and this straight line The slope represents the amount of attenuation per hour (dB / sec) and is an index of attenuation characteristics.

It may be difficult to excite only a single vibration mode as in the above example.
In such a case, evaluation is possible by extracting only the necessary frequency spectrum and reproducing the vibration waveform of only a specific frequency component by the inverse FFT.
In this case, the vibration waveform is Fourier transformed by FFT to obtain the frequency spectrum.
Only the frequency derived from the vibration mode reflecting the characteristics of the sealing material specified by the above-mentioned experimental mode analysis or the like can be extracted, and the vibration waveform can be reproduced by the inverse FFT.

If the frequency derived from the vibration mode reflecting the characteristics of the sealing material is in the low frequency region (6 kHz or less) and the vibration mode derived from the structure is in the high frequency region (8 kHz or more), vibration is applied. It is also possible to excite only a specific vibration mode by changing the chip material at the tip of the hammer to a soft material (made of resin or rubber) so as not to excite the high frequency region.

In FIG. 7, the tip 1a attached to the tip of the hammer 1 is interchangeably configured, and a hammer equipped with a metal hard tip, a hammer equipped with a resin medium tip, and a rubber soft tip having different hardness. The measurement result of the frequency spectrum obtained when the vibration test is performed by using the hammers provided with the above is shown.
It was found that a hammer with a hard tip can vibrate up to 10 kHz, a hammer with a medium tip can vibrate up to 5 kHz, and a hammer with a hard rubber soft tip can vibrate up to 4 kHz. It can be seen that a hammer equipped with a rubber soft tip having low hardness can vibrate up to 2 kHz.

It is obtained when the vibration test is performed under the flange surface vibration conditions shown in FIG. 4 (A) described above by properly using four types of hammers that can be excited based on the four types of frequency spectra shown in FIG. FIG. 8 shows a frequency spectrum obtained by Fourier transforming the vibration waveform by FFT.
From the results shown in FIG. 8, a hammer equipped with a hard chip (metal chip) can obtain a frequency spectrum in a wide frequency range from 0 to 10 kHz, but a hammer equipped with a medium chip has a frequency in a frequency domain up to 5 kHz. It can be seen that the spectrum can be obtained, and that the hammer equipped with the soft chip made of rubber having high hardness can obtain the frequency spectrum in the frequency domain up to 2 kHz.
From this, it was found that the target frequency region can be excited by properly using the chips mounted on the hammer.

FIG. 9 is a flowchart when the method for diagnosing deterioration of the sealing material according to the present embodiment described above is carried out, and FIG. 10 is an example of a deterioration diagnosing device for the sealing material used when carrying out the method for diagnosing deterioration of the sealing material. It is a block diagram which shows.
The deterioration diagnosis device A of the present embodiment includes a vibration sensor (acceleration sensor) 2 arranged along the structure 9 described above, and a signal amplifier (vibration sensor amplifier) that receives and amplifies an output signal from the vibration sensor 2. ) 25, a signal analyzer 26 that receives the output from the signal amplifier 25, and a computing device 27 connected to the signal analyzer 26. In FIG. 10, for the sake of simplification of the description, the structure 9 in which the butterfly valve 6 is interposed between the pipe flanges 8 and 8 of the pipes 10 and 10 is abbreviated, and the other end side of the pipes 10 and 10 is shown. The tank 28 and radiator 29 of the transformer connected to the above are briefly described.

As an example, the analyzer 26 and the arithmetic unit 27 shown in FIG. 10 are composed of a personal computer, the arithmetic unit 27 is a CPU, and a storage device such as a memory or a hard disk is mounted on the analyzer 26. Further, the storage device of the analyzer 26 has a function of displaying the vibration waveform shown in FIG. 5 (A) in decibels and calculating the slope of the straight line shown in FIG. 5 (B) to calculate the attenuation amount, and FIG. 5 (A). ) Is subjected to Fourier transform by FFT to obtain a graph of the frequency spectrum shown in FIG. 4 (A).
In addition, a function for diagnosing deterioration of the sealing material from the relationship between the damping amount ratio and the compression set amount shown in FIG. 6 to be described later is incorporated, and vibration is performed by inverse FFT from a specific peak in the frequency spectrum shown in FIG. 4 (B). It has a built-in function to obtain the waveform and a function to calculate the amount of attenuation from this vibration waveform via the decibel display.

In the method for diagnosing deterioration of the sealing material according to the present embodiment, the vibration position with respect to the structure 9 is specified in step S1 shown in FIG.
The vibration position is specified by a plurality of coordinate axes with respect to the outer peripheral surfaces of the pipe flanges 8 and 8 of the structure 9 and the outer peripheral surface of the butterfly valve as described above based on FIGS. 2A and 2B. Is set, the vibration position by the hammer 1 is determined in step S1 as described above, the vibration by the hammer 1 is performed in step S2, and the vibration waveform accompanying the vibration by the hammer 1 is measured in step S3 as described above. To do.
After that, the vibration and the measurement are repeated at all the measurement points while changing the installation position of the vibration sensor 2 at each intersection of the coordinate axes. All the graphs of the measurement results of the vibration waveform are recorded in the storage device of the analyzer 26.

The obtained vibration measurement results are individually subjected to Fourier transform by FFT in step S4 to obtain a graph of the frequency spectrum, and the results are recorded in the storage device of the analyzer 26.

When the measurement is completed at all the measurement points, the vibration mode is visualized in step S6. For example, in the case of the structure 9 shown in FIG. 2 (A), the butterfly valve 6 is the vibration mode as a single structure. Check if you have.
If it can be determined by visualization that the butterfly valve has a vibration mode as a single structure, measurement is performed in the following order as described above.

In order to excite the expansion / contraction vibration of the butterfly valve 6 as a single structure more strongly, the side surface of the butterfly valve 6 and the measurement point “S14” are vibrated. For the measurement, the measurement point "S14" is vibrated with the vibration sensor attached to the measurement point "S1" to acquire data. Next, the vibration sensor is moved to the measurement point “S2”, and the measurement point “S14” is vibrated to acquire data. Next, the measurement points are sequentially moved from S3 to S35 except for the measurement point "S14", and the measurement point "S14" is vibrated to acquire data.

The graph of the frequency spectrum is confirmed in step S5, and it is not a graph of a complicated waveform including a plurality of vibration peaks as shown in FIG. 4 (A), but one simple one as shown in FIG. 4 (B). In the case of a graph having a vibration peak, the original vibration waveform shown in FIG. 5 (A) before the Fourier conversion in step S7 is converted to the decibel display shown in FIG. 5 (B), and the inclination of the linear portion is performed. Is calculated by the arithmetic unit 27 to obtain the attenuation ratio (dB / sec).
Here, the vibration data is acquired by measuring at a measurement point that seems appropriate (in the case of a butterfly valve, the side surface is vibrated and the vibration is measured in the same axial direction as the vibration direction), and the frequency spectrum is confirmed. If one frequency characteristic is obtained, the process proceeds to step S7, and if a complicated frequency characteristic is obtained or a more detailed evaluation is required, visualization is performed in step S6 to specify the frequency to be analyzed.

Further, when the frequency spectrum graph is confirmed in step S5 and it is confirmed in step S5 that the graph is a complex waveform including a plurality of vibration peaks as shown in FIG. 4 (A), step S8 The spectrum of the specific frequency is extracted as described above, and the inverse FFT conversion is performed as described above in step S9 to reproduce the vibration waveform of only the specific frequency component.
When multiple peaks appear by Fourier transform by FFT, if the peaks are sufficiently separated, the raw waveform (vibration waveform) of only the peak to be analyzed by inverse FFT transform is extracted, ignoring the amplitude other than the peak to be analyzed. The amount of attenuation can be obtained from this vibration waveform.

One of the methods is called "one degree of freedom local fit method". In addition, in order to obtain more accurate attenuation if the peaks are not sufficiently separated, it is necessary to obtain the frequency and attenuation for a plurality of peaks at the same time by a method called "global fit method with multiple degrees of freedom".
The analysis method is complicated, but it can be easily calculated by using commercially available calculation software. In this embodiment, analysis can be performed using the analysis software ME'scope VES manufactured by Vibrant Technology.

For example, from the frequency spectrum shown in FIG. 4 (A), only the frequencies derived from the vibration mode reflecting the characteristics of the sealing material specified in the above-mentioned experimental mode analysis or the like are extracted as shown in FIG. 4 (B). The vibration waveform as shown in FIG. 5A and the like can be reproduced by the inverse FFT conversion.
From this vibration waveform, the decibel display can be performed as shown in FIG. 5B as described above in step S10, and the attenuation amount can be calculated. The details of this method will be described in detail later in Example 3.

Next, in step S11, the arithmetic unit 27 diagnoses the deterioration of the sealing material from the relationship between the compression set ratio and the attenuation ratio.
In the present embodiment, the deterioration of the sealing material is defined by the compression set, and the deterioration of the sealing material can be diagnosed by associating the compression set with the vibration test result.

(Association of compression set with vibration test result: When the amount of damping of new sealant is clear)
The present inventor has the same as the flange 31 of the stainless steel flange bottle 30 shown in FIG. 11 in order to examine the deterioration of the sealing material and the change in the damping amount for the purpose of associating the compression set with the vibration test result. A sealing material (NBR rubber: hardness 60) 33 is sandwiched between the lid plates 32 at a compression rate of 25% and placed in a constant temperature bath set at 100 ° C., 120 ° C., and 150 ° C., and after 100 days have passed. The vibration characteristics (damping amount ratio) and compression set rate of the flange bottle 30 before and after taking out and heating were evaluated.

The flange bottle has a piping portion in which a pipe flange having a thickness of 10 mm and an outer diameter of 130 mm is integrated at both ends of a stainless steel pipe having an outer diameter of 70 mm and an inner diameter of 60 mm. Further, it is a structure in which a stainless steel lid plate having a thickness of 10 mm and an outer diameter of 130 mm is integrated with a bolt via a ring-shaped sealing material having a thickness of 5 mm so as to close both pipe flanges.
The vibration position by the hammer 1 is the upper right corner end of the upper lid plate 32 shown in FIG. 11, and the vibration sensor (accelerometer) 34 is located at the lower left corner end of the upper flange plate 31 diagonally thereof. Was attached and measurement was performed. Further, the other vibration position by the hammer 1 is the upper right corner end of the lower flange plate 31 shown in FIG. 11, and the vibration occurs at the lower left corner of the lower lid plate 32 which is the diagonal position thereof. A sensor (accelerometer) 34 was attached and measurement was performed.

The damping characteristics were evaluated by the ratio of the attenuation before and after heating (attenuation ratio: attenuation after heating [dB / sec] / attenuation before heating [dB / sec]).
In addition, heat treatment was performed with various new sealing materials sandwiched between the lid plate and the flange of the structure shown in FIG. 11, and data was collected when the sealing material was forcibly deteriorated. The heat treatment was performed after the test structure was placed in a constant temperature bath set at 100 ° C., 120 ° C., and 150 ° C., and the heat treatment was performed for a predetermined period. The heating period was 7 to 60 days at 100 ° C., 20 to 100 days at 120 ° C., 12 to 64 days at 150 ° C., and the compression set was deteriorated to 40% to 100%.
The above measurement results are shown in FIG.
As shown in FIG. 6, the damping ratio increases up to a compression set ratio of 60%, but as the deterioration progresses, the damping ratio begins to decrease, and the compression set ratio seems to be the life level of the sealing material up to 90%. When deteriorated, the attenuation ratio decreased by about 20% from the initial value.

In the results shown in FIG. 6, the increase in the damping amount ratio at the initial stage of deterioration is due to the increase in the contact area due to the lateral deformation of the sealing material, and the decrease in the damping amount ratio at the late stage of deterioration is due to the increase in the permanent strain amount. It is thought to be due to the decrease in thickness. Since this increase / decrease in the attenuation ratio is due to a change in the characteristics of the sealing material, it is considered that evaluation is possible regardless of the structure of the object.
As an example, the damping amount of the sealing material when it is new is measured, and after a certain period of time, the damping amount is measured again to obtain the damping amount ratio. Therefore, the sealing material is classified according to the distinction shown in Table 1 below. Deterioration diagnosis is possible.

Specifically, the contents of Table 1 are stored in the storage device of the analyzer 26, the previously obtained measurement results are compared with the contents of Table 1 above, and the arithmetic unit 27 performs a deterioration diagnosis of the sealing material. ..
If the attenuation ratio is 1 or more, it can be continuously used, and it can be judged that the compression set ratio of the sealing material is 80% or less (≦ 80%). If the attenuation ratio is less than 1 to 0.8 or more, the sealing material is deteriorated and the compression set can be judged to be 80 to 90%. If the attenuation ratio is less than 0.8, it can be judged that the sealing material has reached the life level and it is necessary to take measures such as replacement at an early stage.
The arithmetic unit 27 displays these determination results on a display device or the like in step S12, and outputs them as the deterioration diagnosis result of the sealing material.

(When the amount of sealant attenuation when new is unknown)
When the damping amount of the sealing material at the time of a new product is unknown, the damping amount when the compression set is 100% can be specified as the use limit value (limit damping amount).
A certain amount of margin is set for the limit damping amount, and it is possible to diagnose whether or not the sealing material can be continuously used from the damping amount of the structure. The usage limit value can be estimated by producing a structural model of the target structure. In addition, the use limit value can be obtained by conducting a vibration test with only the sealing material removed when removing the equipment, or by manufacturing a structural model using a part of the structure.
The margin α can be arbitrarily set for each target structure, and it is desirable to set it from the amount of attenuation corresponding to the compression set ratio of 70 to 80%. In the case of a butterfly valve that connects the main body of the oil-immersed transformer and the radiator, α = 500 is considered to be suitable as the set value.

The measurement results can be applied to Table 2 above to carry out the diagnosis.
If the damping amount is the limit damping amount + α or more, it can be continuously used, and it can be judged that the compression set ratio of the sealing material is <70 to 80% or less. If the amount of damping is equal to or more than the limit damping amount to less than the limit damping amount + α, it can be determined that the sealing material has deteriorated and the compression set exceeds 70 to 80%. If the amount of attenuation is less than 0.8, it is equivalent to the state without the sealing material, and it can be judged that continuous use is not possible.
The arithmetic unit 27 can display these determination results on a display device or the like in step S12 and output them as the deterioration diagnosis result of the sealing material.

As described above, according to the present embodiment, it is possible to diagnose and grasp the deterioration status of the sealing material attached to the machine, device, piping, etc. in a non-destructive and simple process, and it is necessary to replace the sealing material. Whether or not it can be determined by an external diagnosis.
Hereinafter, the present invention will be described in more detail according to Examples, but the present invention is not limited to the Examples described below.

(First Example)
The primary voltage is 66 kV, the secondary voltage is 6.9 kV, the rated capacity is 6000 kVA, and the main body of the oil-immersed transformer made in 1969 and the accessory radiator are connected via a butterfly valve, and are connected to the connection part of this butterfly valve. The deterioration status of the sealing material used was diagnosed by a vibration test. Since this connection portion has the same structure as that shown in FIG. 2A, the vibration position is set as the side surface of the butterfly valve according to the above-mentioned experimental mode analysis result of the butterfly valve, and the acceleration sensor installed on the opposite side of the vibration surface. The vibration was measured by.
As a result of Fourier transforming the obtained vibration waveform by FFT and obtaining a frequency spectrum, an almost single frequency spectrum was obtained. Therefore, as a result of directly obtaining an attenuation amount from the vibration waveform, an attenuation amount of 2487 dB / sec was obtained. ..

Since the transformer is an existing product, the initial attenuation was unknown. Therefore, a structural model was manufactured using a butterfly valve of the same type used in another transformer in advance, and an initial attenuation of 1520 dB / sec and a limit attenuation of 1056 dB / sec were obtained from the vibration test of the structural model. ..
Based on this result, the attenuation ratio was 1.6, and the sealing material had a compression set ratio of 80% or less, and it was diagnosed that it could be used continuously. Moreover, even when evaluated from the limit attenuation amount, it exceeded the limit attenuation amount + 500 dB / sec, and it was diagnosed that continuous use was possible.
At a later date, I had the opportunity to remove this oil-filled transformer, so when I removed the transformer, I collected the sealing material and measured the compression set, which was 48%, which was consistent with the diagnosis. , It was a sealing material that can be used continuously.

(Second Example)
The primary voltage is 33 kV, the secondary voltage is 6.9 kV, the rated capacity is 6000 kVA, and the main body of the oil-immersed transformer made in 1989 and the accessory radiator are connected via a butterfly valve, which is used for this butterfly valve. The deterioration status of the sealing material was diagnosed by a vibration test.
The vibration sensor position is the same as in (1st Example). As a result of Fourier transforming the obtained vibration waveform by FFT and obtaining a frequency spectrum, an almost single frequency spectrum was obtained. Therefore, as a result of directly obtaining an attenuation amount from the vibration waveform, an attenuation amount of 1686 dB / sec was obtained. ..

As in the first example, the damping amount ratio was calculated to be 1.1 based on the vibration test of the structural model, and the sealing material had a compression set ratio of 80% or less, and it was diagnosed that it could be used continuously. Moreover, even when evaluated from the limit attenuation amount, it exceeded the limit attenuation amount + 500 dB / sec, and it was diagnosed that continuous use was possible. However, there was only a difference of 100 dB / sec with respect to the control standard value of 1556 dB / sec, and it was judged that the deterioration had progressed considerably.
Later, when the transformer was removed, a sealing material was collected and the compression set was measured. As a result, the compression set was 70%, which was in agreement with the diagnosis result.

(Third Example)
Primary voltage 66kV, secondary voltage 6.9kV, rated capacity 15000kVA, butterfly valve connecting the main body of the oil-filled transformer made in 1972 and the radiator was collected when the transformer was removed, and pipe flanges were attached to the front and back of the butterfly valve. A butterfly valve structure model was used, and a vibration test was performed by sandwiching a sealing material equivalent to a compression set of 91%.

The vibration position was the flange surface of the butterfly valve, and the vibration was measured by an acceleration sensor installed on the opposite side of the vibration surface.
The obtained vibration waveform is shown in FIG. 12 (A). The vibration waveform shown in FIG. 12A contains a mixture of a vibration component that attenuates quickly and a vibration component that attenuates slower than the damping, and the amount of damping in a single mode cannot be calculated as it is.
The obtained vibration waveform is Fourier transformed by FFT to obtain the frequency spectrum, and the result is shown in FIG. 12 (B).
As shown in the frequency spectrum shown in FIG. 12B, a plurality of peaks appeared. Each peak represents the magnitude of the response of its own vibration mode. Among these vibration modes, the amount of damping is evaluated for the vibration component in which the viscosity of the sealing material affects the motion.

There are several methods such as inverse FFT conversion, wavelet transform, and Hilbert-Hung transform to separate the overlapping vibration modes and obtain the attenuation amount for each vibration mode. Here, the method using the inverse FFT transform will be described. ..
Even if multiple peaks appear in the FFT transform, if the peaks are sufficiently separated, the raw waveform of only the peak to be analyzed can be extracted by the inverse FFT transform, ignoring the amplitude other than the peak to be analyzed. The amount of attenuation can be obtained.

Such a method is called the "one-degree-of-freedom local-fit method", but if the peaks are not sufficiently separated or more accurate attenuation is obtained, a method called the "multi-degree-of-freedom global fit method" is used. , It is necessary to obtain the frequency and attenuation for multiple peaks at the same time.
The analysis method is complicated, but it can be easily calculated by using commercially available calculation software.
Here, the results of analysis using the analysis software ME'scopeVES manufactured by Vibrant Technology are shown.

First, the peak to be extracted was determined, and curve fitting was performed to obtain the peak frequency and attenuation. The frequency at which the peak exists is determined from the position where the phase of the frequency spectrum is inverted.
In addition, the peak to be extracted analyzes the vibration mode at each frequency and selects the vibration mode related to the movement of the sealing material. In this example, the peak with a frequency of 6.3 kHz was the natural vibration of the butterfly valve alone, so the peak with a frequency of 6.3 kHz was selected.
Next, by reproducing the vibration waveform by inverse FFT conversion on the extracted frequency spectrum, only the vibration waveform at the frequency of 6.3 kHz can be reproduced, and the attenuation amount can be obtained.

According to the analysis software ME'scope VES manufactured by Vibrant Technology, the critical damping ratio (Damping (%)) can be obtained at the time of curve fitting.
Since the critical damping ratio is the ratio of the critical damping coefficient to the actual damping, the critical damping ratio after deterioration (Damping (%)) is divided by the critical damping ratio before deterioration (Damping (%)). The attenuation ratio can also be obtained by this.

As a result of obtaining the attenuation amount from the frequency spectrum shown in FIG. 12 (C) and the vibration waveform shown in FIG. 12 (D) obtained by the inverse FFT analysis, the attenuation amount of 1249 dB / sec could be obtained. As a result of sandwiching a new sealing material in the butterfly valve structure model and obtaining the initial damping amount, the damping amount of 1627 dB / sec could be obtained. When the damping amount ratio was calculated based on this result, it was 0.77, and this sealing material was diagnosed as having a compression set ratio of 90% or more and a life level, which was in agreement with the specifications of the sandwiched sealing material.

(Vibration device)
FIG. 13 is a cross-sectional view showing an example of a vibrating device suitable for vibrating a structure in the present invention.
In the vibration device 40 of this example, a mass-variable hammer 43 having a hammer tip 42 inside the tip side of the hollow exterior body 41 is provided so as to be movable in the front-rear direction along the exterior body 41, and the mass is variable with the hammer tip 42. A force sensor 45 is incorporated between the hammers 43. A screw shaft 46 connected to a mass variable hammer 43 is connected to the rear side of the exterior body 41, and the screw shaft 46 penetrates the rear end wall 41a of the exterior body 41 and projects to the outside of the exterior body 41. ..

A trigger plate 47 pivotally supported by a screw shaft 46 is inserted into the rear end side of a mass-variable hammer 43 on the inner side of the exterior body 41, and is rear of the screw shaft 46 protruding to the outside of the exterior body 41. A release position adjusting nut 48 is screwed to the end. A release spring 49 is wound around a screw shaft 46 located between the rear end wall 41a of the exterior body 41 and the release position adjusting nut 48, and is on the inner side of the exterior body 41, the trigger plate 47 and the exterior body 41. A hammer spring 50 is wound around a screw shaft 46 located between the rear end wall 41a. Further, an insertion hole (not shown) is formed in a part of the rear side wall of the exterior body 41, and a trigger tip 51 is provided so as to penetrate the insertion hole. The trigger tip 51 is configured to pass through the insertion hole on the tip end side thereof so as to enter the inside of the exterior body 41.

A through hole having a size through which the tip of the hammer tip 42 can pass is formed at the tip of the exterior body 41, and a contact plate 53 made of an elastic body is provided so as to cover the through hole. In FIG. 13, the description of the contact plate 53 is omitted, and the contact plate 53 is shown in FIG.
Further, a connection connector 55 for the force sensor 45 is provided on the lower surface side of the tip end portion of the exterior body 41, and a signal transmission cable is connected to the connection connector 55. This cable is connected to the signal analyzer 26 via the amplifier 25 shown in FIG.

The operation of the vibrating device 40 having the above configuration will be described below with reference to FIGS. 14A to 14D.
In the initial state shown in FIG. 14A, the vibration device 40 accommodates the hammer tip 42 in the exterior body 41 in a state in which the tip of the hammer tip 42 is desired slightly inside the tip of the exterior body 41.
From this state, as shown in FIG. 14 (B), the release position adjusting nut 48 is pulled backward to push the hammer spring 50 against the rear end wall 41a of the exterior body 41 while contracting the hammer spring 50, and the trigger plate 47 triggers. After moving to the rear of the tip 51, the trigger tip 51 is pushed into the exterior body 41 to lock the trigger plate 47.

Next, the contact plate 53 of the vibration device 40 is pressed against the vibration position of the structure 9, for example, the vibration position on the side surface of the butterfly valve 6 to stand still.
From this state, when the trigger plate 47 is unlocked by the trigger tip 51 as shown in FIG. 14C, the tip of the hammer tip 42 moves forward due to the spring force of the hammer spring 50, and the hammer tip 42 The tip portion projects a predetermined amount toward the tip of the contact plate 53.
By this operation, the tip of the hammer tip 42 can collide with the side surface of the butterfly valve 6 to apply a constant excitation force to the side surface of the butterfly valve 6.
Compared with the case where the hammer 1 is used for vibration as described in the previous embodiment, a constant vibration force (impact force) is always applied to the side surface of the butterfly valve 6 by using the vibration device 40. Can be done.

After the tip of the hammer tip 42 collides with the side surface of the butterfly valve 6, the release spring 49 collides with the rear end wall 41a of the exterior body 41 and a reaction force acts, so that the hammer tip 42 is inside the exterior body 41. Be pulled back. As a result, the vibration exciter 40 can be returned to the initial state as shown in FIG. 14 (D).
By using the vibration device 40 shown in FIGS. 13 and 14 to apply an impact to each point shown in FIGS. 2 (A) and 2 (B) to vibrate, and recording the vibration waveform using the vibration sensor 2. The object of the present application can be achieved.
With the vibration device 40 shown in FIGS. 13 and 14, vibration can always be performed with a constant striking force, so that vibration can be detected by stable vibration as compared with the case where vibration is performed manually by the hammer 1.
Further, the force sensor 45 provided in the excitation device 40 can measure the excitation force and the frequency characteristics of the excitation force as shown in FIG. 7.

In the examples and embodiments described so far, an example in which the present invention is applied to the structure 9 in which the pipe 10 is connected to both sides of the butterfly valve 6 via the sealing material 7 has been described. However, the scope of application of the present invention is not limited to these examples, and it goes without saying that the present invention may be applied to a structure in which pipes are connected to both sides of one sealing material.
Therefore, the first member and the second member arranged on both sides of the sealing material may be a combination of a butterfly valve and a pipe, a combination of a pipe and a pipe, or a combination of various structures. It may be any case.

1 ... Hammer, 1a ... Chip, 2 ... Vibration sensor (accelerometer), 3 ... Object, 4 ... Sealing material, 6 ... Butterfly valve, 7 ... Sealing material, 8 ... Pipe flange, 9 ... Structure, 10 ... Piping ,
S1, S2, ~ S36 ... Measurement point or vibration point,
A ... Deterioration diagnostic device, 25 ... Amplifier (signal amplifier), 26 ... Signal analyzer, 27 ... Computational device, 28 ... Tank, 29 ... Radiator, 30 ... Flange bottle 30, 31 ... Flange, 32 ... Lid plate, 33 ... Sealing material, 34 ... Vibration sensor (accelerometer),
40 ... Vibration device, 41 ... Exterior body, 42 ... Hammer tip, 43 ... Variable mass hammer, 45 ... Force sensor, 46 ... Screw shaft, 47 ... Trigger plate, 48 ... Release position adjustment nut, 49 ... Release spring, 50 ... hammer spring, 51 ... trigger tip, 53 ... contact plate.

Claims (12)

The vibration generated when the structure is vibrated with respect to the structure connecting the first member and the second member via the sealing material is detected by the vibration sensor installed in the structure, and the detected vibration. Extracting the frequency spectrum of the specific vibration mode via the sealing material from the waveform, calculating the damping amount from the vibration waveform corresponding to the frequency spectrum, and diagnosing the deterioration state of the sealing material based on the damping amount. A sealing material deterioration diagnosis method characterized by. In the sealing material deterioration diagnosis method according to claim 1, when the vibration sensor detects vibration, a plurality of vibration waveforms are observed by changing the vibration position or the vibration direction with respect to the structure, and these vibrations. When the waveform includes a vibration waveform having a frequency spectrum in which a single vibration mode is excited, a damping amount is calculated from this vibration waveform, and the deterioration status of the sealing material is determined based on the damping amount. A method for diagnosing deterioration of a sealing material, which comprises diagnosing. When the measured vibration waveform in the sealing material deterioration diagnosis method according to claim 1 is a vibration waveform in which a vibration component that attenuates quickly and a vibration component that attenuates slowly are mixed, and a vibration waveform in which a plurality of vibration modes overlap. , The required frequency spectrum is extracted from this vibration waveform, the vibration waveform of the vibration mode of only a specific peak is obtained from this frequency spectrum by inverse calculation, the damping amount is obtained from this vibration waveform, and the seal is based on this damping amount. A method for diagnosing deterioration of a sealing material, which comprises diagnosing a deterioration state of a material. In the sealing material deterioration diagnosis method according to any one of claims 1 to 3, the amount of damping of the sealing material when it is new is measured, and after a certain period of time, the amount of damping of the sealing material is again measured. A method for diagnosing deterioration of a sealing material, which comprises measuring and obtaining a damping amount ratio and diagnosing deterioration of the sealing material according to a deterioration evaluation standard based on a predetermined damping amount ratio. In the sealing material deterioration diagnosis method according to any one of claims 1 to 4, the damping amount when the compression set is 100% is defined as the use limit value (limit damping amount), and the limit damping amount is used. A sealing material deterioration diagnosis method characterized by diagnosing deterioration of a sealing material according to a deterioration evaluation standard that defines a certain amount of margin. In the method for diagnosing deterioration of a sealing material according to claim 3, when the vibration waveform of the vibration mode of only a specific peak is obtained by an inverse calculation, any one of inverse FFT conversion, wavelet conversion, and Hibert-Huang conversion is used. Sealing material deterioration diagnosis method. The structure that connects the first member and the second member via the sealing material receives a vibration waveform due to vibration generated when the structure is vibrated from the vibration sensor, and the sealing material is received from the vibration waveform. A calculation means for extracting the frequency spectrum of a specific vibration mode via the above and calculating the damping amount from the vibration waveform corresponding to the frequency spectrum, and the deterioration status for determining the deterioration status of the sealing material based on the damping amount. A seal material deterioration diagnostic device characterized by being provided with a determination means. A plurality of vibration waveforms are observed by the vibration sensor by changing the vibration position or the vibration direction with respect to the structure, and the vibration waveform has a frequency spectrum in which a single vibration mode is excited. The seal material deterioration diagnostic apparatus according to claim 7, wherein the calculation means has a function of calculating a damping amount from the vibration waveform when the vibration waveform is included. When the measured vibration waveform is a vibration waveform in which a vibration component that decays quickly and a vibration component that decays slowly are mixed, and a vibration waveform in which a plurality of vibration modes overlap, a necessary frequency spectrum is extracted from this vibration waveform. The sealing material according to claim 7, wherein the calculation means has a function of obtaining a vibration waveform of a vibration mode of only a specific peak from this frequency spectrum by an inverse calculation and obtaining a damping amount from the vibration waveform. Deterioration diagnostic equipment. The amount of damping of the sealing material when it is new is stored in the deterioration status determining means, and the damping amount ratio of the sealing material measured after a certain period of time is compared with the amount of damping when the sealing material is new is compared in advance. The sealing material deterioration diagnostic apparatus according to claim 7, wherein the deterioration status determining means is provided with a function of diagnosing deterioration of the sealing material according to a deterioration evaluation standard based on a predetermined attenuation ratio. The amount of attenuation when the compression set is 100% is recorded in the deterioration status determination means as the use limit value (limit attenuation amount), and the sealing material is deteriorated according to the deterioration evaluation standard in which a certain amount of margin is set for the limit attenuation amount. The seal material deterioration diagnostic apparatus according to any one of claims 7 to 10, further comprising a function of diagnosing. The sealing material according to claim 9, wherein any of inverse FFT conversion, wavelet conversion, and Hibert-Huang conversion is applied as a function of obtaining the vibration waveform of the vibration mode of only a specific peak by inverse calculation. Deterioration diagnostic equipment.

Images