JP2019152538A - Fastening bolt fastening torque specifying device and fastening torque specifying method - Google Patents

Abstract

To provide a fastening bolt fastening torque specifying device and fastening torque specifying method with which it is possible to specify the fastening torque in the current state of a fastening bolt without directly touching the existing fastening bolt.SOLUTION: Provided is a fastening bolt fastening torque specifying device 100 for specifying the fastening torque of a fastening bolt B with a body P to be fastened is fastened by a nut N via a washer W, the device comprising: exciting means 10 for shaking the body P to be fastened; vibrometers 20, 30 for measuring the vibration of the body P to be fastened and the washer W; and a computer 50 in which a conversion program for converting the measured data by the vibrometers 20, 30 into a frequency component is stored, and also relation data representing the relation of the fastening torque of the fastening bolt B and the frequency of the washer W is stored.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tightening torque specifying device and a tightening torque specifying method for a tightening bolt.

  In various existing structures, when the structural members are fastened with fastening bolts, the nut may be loosened due to the influence of continuous vibration or the like. Conventionally, various methods for quantitatively detecting the looseness of the nut have been proposed. One method is to cover the left contact terminal and the right contact that are electrically connected from the output terminal to the nut by covering the nut that is fastened to the bolt with an insulating nut cap to which a conductive magnet is attached. Tighten the screwed bolt cap consisting of the terminal to the end of the bolt. Then, when a counterclockwise rotational displacement of the nut that occurs due to the loosening of the nut occurs, it is a method of releasing the electrical continuity by releasing the contact and notifying the looseness of the nut (see, for example, Patent Document 1). .

  Another method is a method of obtaining the axial force of the bolt by utilizing the characteristic that the natural frequency of the bolt varies depending on the magnitude of the axial force of the bolt. Specifically, the natural frequency of the bolt is determined by striking the bolt with a hammer, measuring the sound and vibration generated at that time, and analyzing the frequency of the sound and vibration. The axial force of the bolt is obtained by associating the frequency with the relation between the axial force of the bolt and the natural frequency obtained experimentally or experimentally (see, for example, Patent Document 2).

JP 2017-26134 A JP 2002-340710 A

  However, in the method of informing the loosening of the nut described in Patent Document 1, the nut cap is put on the nut fastened to the bolt, so that the weight of the put nut cap is added to the weight of the tightening bolt and the nut. In addition to the increase in weight, there is a risk of changing the state of the current tightening bolt and nut due to the nut cap. For this reason, it is difficult to accurately specify the current looseness of the nut. In addition, the method of obtaining the axial force of the bolt described in Patent Document 2 is also unavoidable to change the state of the actual tightening bolt because the bolt is directly hit with a hammer or the like. It becomes difficult to specify the axial force with high accuracy.

  The present invention has been made in view of the above problems, and a tightening torque specifying device for a tightening bolt capable of specifying the current tightening torque of a tightening bolt with high accuracy without directly contacting an existing tightening bolt, and The object is to provide a method for identifying tightening torque.

In order to achieve the above object, one aspect of the tightening bolt tightening torque specifying device according to the present invention is to tighten a tightening bolt that specifies a tightening torque of a tightening bolt whose body to be fastened is tightened with a nut via a washer. A torque identification device,
Vibration means for vibrating the fastened body;
A vibrometer for measuring vibrations of the fastened body and the washer;
And a computer storing a conversion program for converting measurement data obtained by the vibration meter into a frequency component, and storing data related to the tightening torque of the tightening bolt and the frequency of the washer.

  According to this aspect, the vibration of the washer is measured by the vibration meter to identify the frequency of the washer (for example, the natural frequency), and the frequency of the identified washer is related to the tightening torque of the tightening bolt and the frequency of the washer. , The tightening torque of the tightening bolt can be specified from the frequency of the washer. In other words, the tightening torque specifying device of this aspect specifies the current tightening torque of the tightening bolt without contacting any nuts or tightening bolts, and therefore can accurately determine the current tightening torque of the tightening bolt. it can. That is, it is possible to make a high-precision quantitative determination such as the current tightening torque of the tightening bolt rather than a qualitative determination such as the current degree of looseness of the tightening bolt.

  There are a case where the body to be fastened is a metal member such as a steel material and a plastic member, and a tightening bolt and a nut are a combination of a metal nut and a metal bolt, and a combination of a plastic nut and a plastic bolt. The nuts and bolts targeted by the tightening torque specifying device of this aspect are bolts and nuts made of various materials such as metal bolts and plastic bolts. In addition, since the material type of the washer also changes depending on the material type of the tightening bolt and nut, for example, a metal washer is used for the metal tightening bolt and nut, and the plastic tightening bolt and nut are used. For this, a plastic washer is used. Moreover, as a metal washer, various metal seed | species, such as iron and aluminum other than general carbon steel, is mentioned. Further, the size of the washer changes according to the nominal diameter (M10, M20, etc.) of the tightening bolt.

  Here, there are various forms of vibrating means for vibrating a body to be fastened (for example, a metal plate, etc.), in addition to a vibrator that can freely vibrate sine wave vibration, square wave vibration, etc. (Square wave vibration can be generated by such hammer hitting), and also include vibrations transmitted from the surrounding environment and machine vibrations generated in the factory. it can.

  Further, the vibrometer that measures the vibrations of the fastened body and the washer may be a common vibrometer, or may be a vibrometer specific to the fastened body and the washer. Also, the computer stores a conversion program for converting the frequency of a vibration time history waveform measured by, for example, a vibrometer, and further stores relational data between the tightening torque of the tightening bolt and the frequency of the washer. By this conversion program, the vibration waveforms of the fastened object and the washer measured by the vibrometer are frequency-converted, and the respective frequencies (for example, natural frequencies) are analyzed. Relationship data between the tightening torque of the tightening bolt and the frequency of the washer is specified in advance, and this relationship data is stored in the computer. For example, by measuring the vibration waveform of the washer at each tightening torque while changing the tightening torque of the tightening bolt, and converting the frequency to specify the frequency of the washer, the washer for each tightening torque of the tightening bolt is determined. Are identified. For example, plot the washer frequency for each tightening torque on a two-dimensional coordinate consisting of coordinates indicating the tightening torque and coordinates indicating the frequency of the washer, and by connecting a plurality of plots, or obtaining an approximate curve of the plurality of plots, etc. Thus, the relationship data (relation graph) can be specified.

  In addition, since the to-be-fastened body is vibrated by the vibration means, and the washer is vibrated by this vibration, the vibration at the time of vibration such that the washer resonates with respect to the vibration to be vibrated is set. preferable. When the washer resonates, its vibration is increased as much as possible, and the vibration measurement of the washer by the vibrometer is improved.

  According to another aspect of the tightening bolt tightening torque specifying device according to the present invention, in the computer, only the frequency of the washer is specified, and the frequency of the washer is applied to the relational data to determine the tightening torque of the tightening bolt. It is characterized by being specified.

  According to this aspect, the tightening torque of the tightening bolt to be measured is specified by applying the specified washer frequency to the relational data between the tightening torque and the washer frequency already created.

  According to another aspect of the tightening bolt specifying torque tightening device according to the present invention, the vibration meter is a laser vibrometer that obtains a reflected laser by irradiating the washer with a laser, or a piezoelectric element attached to the washer. It is any one of these.

  According to this aspect, since any vibrometer does not cause a large weight increase with respect to the washer, it is possible to specify the vibration of only the washer. In the case of using a laser vibrometer that irradiates a washer with a laser to acquire a reflected laser, there is no weight increase on the washer, and therefore it is possible to specify vibration of only the washer. An example of this laser vibrometer is a laser Doppler vibrometer. On the other hand, when the piezoelectric element attached to the washer is a vibrometer, the piezoelectric element (piezo film) is extremely lightweight, so there is almost no increase in the weight of the washer, and therefore the vibration of the washer can be specified with high accuracy. It becomes possible. Moreover, the form which applies a piezoelectric element to a vibrometer becomes practical from a viewpoint of the conveyance property to an actual field, and favorable measurement property. For example, by frequency-converting the vibration of the washer that vibrates on the fastened body, for example, both the frequency of the washer and the fastened body (for example, the natural frequency) can be specified. When either one of the frequency bands is known from, for example, an empirical rule, it is possible to specify the frequency of the washer from a plurality of frequencies obtained by analysis.

Further, in another aspect of the tightening torque specifying device for tightening bolts according to the present invention, the vibrometer for measuring the vibration of the fastened body and the washer comprises a vibrometer specific to the measurement of each vibration,
The vibrometer for measuring the vibration of the fastened body comprises a pickup,
The vibrometer that measures the vibration of the washer is either a laser vibrometer that irradiates the washer with a laser to obtain a reflected laser, or a piezoelectric element that is attached to the washer. .

  According to this aspect, by measuring the vibration of the fastened body with the pickup and measuring the vibration of the washer with the laser vibrometer or the piezoelectric element, it becomes possible to identify both vibrations with higher accuracy. . Actually, since the vibration mode (frequency and magnitude of vibration) of the fastened body and the vibration mode of the washer are different, it is more accurate to measure each vibration with an individual vibrometer. Vibration measurement is possible. As a result, the frequency based on each vibration data can be obtained with high accuracy by analysis, and the frequency of the washer can be specified with high accuracy.

Further, one aspect of the tightening torque specifying method of the tightening bolt according to the present invention is a tightening torque specifying method of the tightening bolt for specifying the tightening torque of the tightening bolt whose body to be fastened is tightened with a nut through a washer. And
A vibration step of vibrating the fastened body;
A vibration measuring step for measuring vibrations of the fastened body and the washer;
After converting the measurement data measured in the vibration measurement step into a frequency component, the frequency of the washer is specified, a washer frequency specifying step,
A relationship data identification step for identifying relationship data between the tightening torque of the tightening bolt and the frequency of the washer;
The tightening torque of the tightening bolt is specified by applying the frequency of the washer specified in the washer frequency specifying step to the related data specified in the related data specifying step.

  According to this aspect, since the current tightening torque of the tightening bolt is specified without contacting the nut or the tightening bolt at all, the current tightening torque of the tightening bolt can be accurately identified.

Another aspect of the tightening torque specifying method for the tightening bolt according to the present invention is as follows.
Measurement of vibration of the fastened body and vibration of the washer by irradiating the washer with a laser to obtain a reflected laser, and measuring with the piezoelectric element by attaching a piezoelectric element to the washer It is performed by any one of these.

  According to this aspect, since neither of the vibrometers causes a large increase in weight with respect to the washer, both the fastened object and the washer can be vibrated under the current tightening state, and measurement regarding this vibration is performed. The frequency of the washer can be specified based on the frequencies of both the fastened object and the washer that are specified by frequency-converting the measured data.

Another aspect of the tightening torque specifying method for the tightening bolt according to the present invention is as follows.
Measure the vibration of the fastened body with a pickup,
Measurement of the vibration of the washer is performed by any one of a method of irradiating the washer with a laser to obtain a reflected laser, and a method of attaching a piezoelectric element to the washer and measuring with the piezoelectric element. It is characterized by that.

  According to this aspect, by measuring the vibration of the fastened body with the pickup and measuring the vibration of the washer with the laser vibrometer or the piezoelectric element, it becomes possible to identify both vibrations with higher accuracy. . As a result, the frequency based on each vibration data can be obtained with high accuracy by analysis, and the frequency of the washer can be specified with high accuracy.

  According to the tightening bolt specifying device and the tightening torque specifying method of the present invention, it is possible to specify the current tightening torque of the tightening bolt with high accuracy without directly contacting the existing tightening bolt.

It is a figure which shows an example of the clamping torque specific device which concerns on 1st Embodiment. It is a figure which shows an example of the hardware constitutions of a computer. It is a figure which shows an example of a function structure of a computer with an external device. It is a flowchart which shows an example of the tightening torque specific method which concerns on embodiment. It is a figure which shows the measurement data by a vibrometer, Comprising: (a) is a figure which shows the measurement data (time history waveform) by a laser vibrometer, (b) is a figure which shows the measurement data (time history waveform) by a pickup. is there. A frequency spectrum obtained by frequency-converting measurement data obtained by a vibrometer when the tightening torque is 2.5 Nm, (a) is a frequency spectrum of measurement data obtained by a laser vibrometer, and (b) is a frequency spectrum of measurement data obtained by a pickup. It is. A frequency spectrum obtained by frequency-converting measurement data obtained by a vibration meter when the tightening torque is 12.5 Nm, (a) is a frequency spectrum of measurement data obtained by a laser vibrometer, and (b) is a frequency spectrum of measurement data obtained by a pickup. It is. It is a figure which shows an example of the relationship graph of a fastening torque and a washer frequency. It is a figure which shows an example of the clamping torque specific device which concerns on 2nd Embodiment. It is a figure which shows the relationship graph of a fastening torque and a washer frequency at the time of changing the frequency band by a vibration exciter.

  Hereinafter, embodiments relating to a tightening torque specifying device and a tightening torque specifying method for a tightening bolt will be described with reference to the accompanying drawings. In addition, in this specification and drawing, about the substantially same component, the duplicate description may be abbreviate | omitted by attaching | subjecting the same code | symbol.

[First Embodiment]
<Tightening torque identification device>
First, a tightening torque specifying device according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a diagram illustrating an example of a tightening torque specifying device according to the first embodiment. FIG. 2 is a diagram illustrating an example of a hardware configuration of a computer, and FIG. 3 is a diagram illustrating an example of a functional configuration of the computer together with an external device.

  As shown in FIG. 1, the tightening torque specifying device 100 fastens the vibration exciter 10 that applies vibration to the fastened body P, the pickup 20 that measures the vibration of the fastened body P, and the fastened body P. A laser vibrometer 30 that measures the vibration of the washer W interposed between the tightening bolt B and the nut N, and a computer 50 to which measurement data in the pickup 20 and the laser vibrometer 30 are input. Although the to-be-fastened body P of the example of illustration consists of two metal plates P1 and P2 from which thickness differs, various to-be-fastened bodies P other than an example of illustration may be sufficient. Since the two metal plates P1 and P2 are bolted together, all the members of the fastening bolt B, the nut N, and the washer W are metal members, but when the fastened body P is made of, for example, two plastic members. All members of the fastening bolt B, the nut N, and the washer W can be plastic members. There are various nominal diameters such as M10, M12, and M20 for the tightening bolts B. A specific standard tightening torque is set for each nominal diameter of the tightening bolt B, and the size of the applied washer W is large. In addition, the one corresponding to the tightening bolt B of each nominal diameter is applied.

  The tightening torque specifying device 100 is used in principle in two phases. The first phase is a phase in which, for example, in the test chamber, the relationship data between the tightening torque of the tightening bolt B and the frequency of the washer W is specified. In this case, the fastened body P becomes a test body, and the vibration of the washer W or the like is measured by varying the tightening torque of the tightening bolt B with respect to the fastened body P that is the test body, and the frequency of the washer W ( For example, the natural frequency) is specified. On the other hand, the second phase is a phase for actually evaluating the tightening torque of the tightening bolt B of the body P to be fastened in the existing structure. In this case, the fastened body P is an existing structure. Therefore, vibration is applied to the fastened body P which is the existing structure, the frequency of the washer W (for example, the natural frequency) is specified, and the frequency of the specified washer W is specified in the first phase. By applying to the related data, the tightening torque of the tightening bolt B that fastens the fastened body P, which is an existing structure, is specified. As described above, the fastened body P becomes the test body and the existing structure by the phase to which the tightening torque specifying device 100 is applied.

  The vibrator 10 can selectively generate sine wave vibration and square wave vibration of various frequency bands, and can change the frequency band between 1 kHz and 10 kHz, for example. In addition to the shaker 10 of the illustrated example that automatically applies vibrations, the inspector applies a shock to the fastened body P with a hammer as a vibration means, so that a square wave vibration in a low frequency band is obtained. May be given. Further, particularly in the measurement of the existing structure (second phase described above), traffic vibration propagated to the existing structure may be used as the excitation means. In the present embodiment, a highly practical vibrator 10 is applied as a vibration means. The vibration exciter 10 may be composed of a magnetostrictive element and a signal generator. In order to effectively propagate the vibration generated by the vibration exciter 10 to the fastened body P, a predetermined amount is provided on the top of the vibration exciter 10. A heavy weight may be placed.

  In the fastened object P in the test chamber, the frequency characteristics of the washer W can be specified with high accuracy by measuring the vibration of the washer W on a stable flat substrate. From such a viewpoint, the lower metal plate P2 is a thick metal plate (for example, a thickness of about 10 mm), the metal plate P2 is a substrate, and a relatively thin metal plate P1 (for example, a thickness of about 5 mm) is formed thereon. The metal plate) is placed and fastened to each other by bolts to form a fastened body P as a test body. Further, the fastened body P that is a test body is configured to fasten the two metal plates P1 and P2 with two tightening bolts B as in the illustrated example, but the number of the tightening bolts B is not limited to the illustrated example. It is not something. Further, in order to efficiently perform a test using tightening bolts having different nominal diameters such as M10 and M12, in the two metal plates P1 and P2, for example, a bolt hole for M10, a bolt hole for M12, and a bolt for M20 Bolt holes having a plurality of types of nominal diameters such as holes may be opened.

  A pickup 20 that measures the vibration of the fastened body P is placed on the upper surface of the fastened body P, and time history data relating to the vibration speed, vibration acceleration, and the like of the fastened body P is measured by the pickup 20. As the pickup 20, for example, a triaxial acceleration sensor can be applied. A sensor amplifier 41 for signal amplification is connected to the pickup 20. The sensor amplifier 41 is connected to an A / D converter 43, and an analog signal amplified by the sensor amplifier 41 is output from the A / D converter 43. After being converted into a digital signal, it is input to the computer 50 to which the A / D converter 43 is connected.

  On the other hand, a laser vibrometer 30 for measuring the vibration of the washer W is attached to the vertical support member 31 so as to be movable up and down, and the laser vibrometer 30 is fixed at a desired height position. When the vibrator 10 vibrates, the fastened body P vibrates, and the vibration of the fastened body P vibrates the washer W. Therefore, for example, the amplitude of the washer W can be increased by adjusting both the rigidity so that the fastened body P and the washer W resonate or by adjusting the frequency band of vibration by the vibrator 10. It becomes possible to measure the vibration of W with higher accuracy.

  The laser L is irradiated from the laser vibrometer 30 to the washer W that vibrates together with the fastened object P, and the laser vibrometer 30 acquires the reflected laser reflected by the washer W. As the laser vibrometer 30, a laser Doppler vibrometer can be applied. The laser vibrometer 30 measures time history data relating to the vibration speed, vibration acceleration, and the like of the washer W. A controller 42 for signal amplification is connected to the laser vibrometer 30, the controller 42 is connected to an A / D converter 43, and an analog signal amplified by the controller 42 is digitally converted by the A / D converter 43. After being converted into a signal, the signal is input to the computer 50 to which the A / D converter 43 is connected.

  The tightening torque specifying device 100 may not include the pickup 20 and may have only the laser vibrometer 30 as a vibrometer. The vibration time history data measured by the laser vibrometer 30 is the vibration time history data of the washer W caused by the vibration of the fastened body P. The element to be specified by the tightening torque specifying device 100 is the frequency (for example, the natural frequency) of the washer W. The time history data of the vibration of the washer W caused by the vibration of the fastened body P is measured. Therefore, in the frequency band obtained by converting the frequency component, a frequency specific to the fastened body P and a frequency specific to the washer W are generally included. When the frequency band of the to-be-fastened body P and the washer W is different and one of them is known, for example, on the experience side, it is possible to specify a frequency specific to the washer W from a plurality of frequency bands. Therefore, in such a case, a form having only the laser vibrometer 30 as the vibrometer can be applied.

  As shown in FIG. 2 as an example of a hardware configuration, a computer 50 includes a CPU (Central Processing Unit) 501, a RAM (Random Access Memory) 502, a ROM (Read Only Memory) 503, an NVRAM (Non-Volatile RAM) 504, An HDD (Hard Disc Drive) 505, a display device 506, an input I / F 507, and an output I / F 508 are connected to each other via a bus 509.

  The ROM 503 stores various programs and data used by the programs. The RAM 502 is used as a storage area for loading a program and a work area for the loaded program. The CPU 501 realizes various functions by processing a program loaded in the RAM 502. The NVRAM 504 stores various setting information. The HDD 505 stores programs and various data used by the programs. For example, the ROM 503 includes an analysis program that converts input time history data of vibrations of the fastened object P and the washer W into frequency components, and a program that specifies (extracts) the frequency of the washer W. In addition, a program for specifying (creating) relationship data between the tightening torque of the tightening bolt B and the frequency of the washer W is included. Furthermore, the frequency of the washer W of the fastened body P that is an existing structure is specified, and the frequency of the specified washer W is applied to related data, thereby fastening the fastened body P that is an existing structure. A program for specifying the tightening torque of the tightening bolt B is included.

  Via the input I / F 507, time history data of vibrations of the fastened body P and the washer W converted into digital signals by the A / D converter 43 is input. Further, when creating the relationship data of the tightening torque of the tightening bolt B and the frequency of the washer W, the tightening torque value that is repeatedly set is input at any time, and in the computer 50, the vibration time history for each input tightening torque value. The data and the frequency of the washer W are stored in a manner linked to the corresponding tightening torque value.

  The output I / F 508 is equipped with an electronic component such as an antenna that is necessary for communication in a wireless LAN or a mobile communication network. For example, vibration measurement data and analysis data relating to an existing structure are transmitted to a computer in the management building.

  The display device 506 includes a time history waveform of vibration of the fastened body P and the washer W, relational data of the tightening torque of the fastening bolt B and the frequency of the washer W, and the frequency of the washer W of the fastened body P that is an existing structure. A specific value related to is displayed.

  As shown in FIG. 3 as an example of a functional configuration, the computer 50 receives time history data of vibrations of the fastened object P and the washer W transmitted from the pickup 20 and the laser vibrometer 30 which are external devices. A data input unit 510. In the phase of specifying the relationship data between the tightening torque of the tightening bolt B and the frequency of the washer W, the set tightening torque value is also input to the data input unit 510 together with the vibration time history data. For example, time history data of vibration of the fastened object P and the washer W is input under the title <Time history data of tightening torque 2.5 Nm>. In the phase of actually evaluating the tightening torque of the tightening bolt B of the body P to be fastened in the existing structure, for example, <Bridge XX, No. Peer, no. Under the title of 5 volts>, time history data of vibrations of the fastened body P and the washer W is input.

  The frequency component conversion unit 512 stores, for example, a fast Fourier transform (FFT) program, and the vibration time history data input to the data input unit 510 is frequency component converted by the fast Fourier transform program. And the spectrum for every frequency of the to-be-fastened body P and the washer W is specified. The vibration time history data measured by the pickup 20 is time history data unique to the fastened body P. On the other hand, since the vibration time history data measured by the laser vibrometer 30 is the vibration time history data of the washer W caused by the vibration of the fastened body P, in the frequency band obtained by converting the frequency component. In general, a frequency specific to the fastened body P and a frequency specific to the washer W are included.

  Therefore, in the washer frequency specifying unit 514, the two frequency analysis data created in the frequency component conversion unit 512, that is, the frequency analysis data based on the measurement by the pickup 20, and the frequency analysis data based on the measurement by the laser vibrometer 30, And the peak value other than the peak value in the frequency band common to both (the frequency of the fastened object P) can be specified as the frequency unique to the washer W.

  In the phase of specifying the relationship data between the tightening torque of the tightening bolt B and the frequency of the washer W in the test room or the like, the tightening torque of the tightening bolt B in the test body is, for example, 2.5 Nm case, 5 Nm case, 7 For each of a plurality of tightening torque cases such as a 5 Nm case,..., A 15 Nm case, vibration is applied to the test body, and vibrations of the fastened body P and the washer W are measured at that time, and each frequency component is converted. After that, the frequency of the washer W is specified.

  Therefore, in the relational data specifying unit 516, the frequency of the washer W in the case where the tightening torque of the tightening bolt B is 2.5 Nm is 5000 Hz, and the frequency of the washer W in the case where the tightening torque is 10 Nm is 6000 Hz. The frequency of the washer W is specified. In this way, the relationship data of the tightening torque of the tightening bolt B and the frequency of the washer W is specified based on the frequency of the washer W for each specified tightening torque. The relationship data storage unit 518 stores the relationship data specified by the relationship data specifying unit 516.

  In the phase of actually evaluating the tightening torque of the fastening bolt B of the fastened body P in the existing structure, vibration is applied from the vibrator 10 to the fastened body P in the existing structure and input from each vibration meter. The vibration time history data is input to the data input unit 510 and frequency-converted by the frequency component conversion unit 512, and then the frequency of the washer W is specified by the washer frequency specifying unit 514.

  The tightening torque specifying unit 520 reads the frequency of the washer W specified by the washer frequency specifying unit 514, reads related data from the related data storage unit 518, and applies the frequency of the washer W to the read related data. The relational data includes, for example, a linear function and a quadratic function. By applying the frequency of the washer W to the function and reading the tightening torque value of the tightening bolt B corresponding to this frequency, the tightening in the existing structure is performed. The tightening torque of the tightening bolt B of the body P is specified. The data output unit 522 outputs related data, the tightening torque of the specified tightening bolt B, or the like on a screen, or transmits it to a computer in a management building, for example, via a communication line.

<Tightening torque identification method>
Next, a tightening torque specifying method according to the embodiment of the present invention will be described with reference to FIGS. Here, FIG. 4 is a flowchart showing an example of the tightening torque specifying method according to the embodiment. As shown in FIG. 4, the tightening torque specifying method has a flow corresponding to two phases. The first phase is a phase in which, for example, in the test chamber, the relationship data of the tightening torque of the tightening bolt B and the frequency of the washer W is specified, and the flow is until the relationship data is specified. This flow is shown in the upper part of FIG. On the other hand, the second phase is a phase for actually evaluating the tightening torque of the tightening bolt B of the fastened body P in the existing structure, and is a flow until the tightening torque in the existing structure is specified. This flow is shown in the lower part of FIG.

  First, referring to the flowchart in the upper part of FIG. 4, a method for specifying the relationship data between the tightening torque of the tightening bolt B and the frequency of the washer W will be described. In this relational data, it is necessary to specify the frequency of the washer W for each of various tightening torques. Therefore, in step S600, the initial tightening torque is set. For example, when the standard tightening torque of the M10 tightening bolt B is 24.5 Nm, 2.45 Nm corresponding to 10% is set as the tightening torque, and the fastened body P is tightened under this tightening torque. . At this time, as shown in FIG. 1, the tightening bolt B is tightened with the nut N via the washer W.

  In step S602, for example, the vibrator 10 is operated to vibrate the fastened body P that is a test body (vibration process). The vibration generated by the vibrator 10 includes sine wave vibration and square wave vibration. Moreover, although the frequency band of vibration can also be set arbitrarily, it is preferable to adjust the frequency band of the vibration to be generated so that the washer W can resonate and vibrate with a large amplitude with respect to the vibration of the fastened body P.

  In step S604, the vibration speed and the like of the fastened body P are measured by the pickup 20, and the vibration speed and the like of the washer W are measured by the laser vibrometer 30 (vibration measurement process). The vibration measurement by the laser vibrometer 30 is performed by irradiating the surface facing the outside of the washer W with a laser from the laser vibrometer 30 and acquiring the reflected laser reflected by the surface of the washer W by the laser vibrometer 30. Here, the measurement data by each vibration meter is shown in FIG. FIG. 5A is a diagram showing an example of measurement data (time history waveform) by a laser vibrometer, and FIG. 5B is a diagram showing an example of measurement data (time history waveform) by a pickup.

  The time example waveform data shown in FIG. 5 is data when a sine wave vibration of 7 kHz is applied by the vibrator 10 using an M10 iron washer. In both FIGS. 5A and 5B, the horizontal axis indicates time by lot number, and in the illustrated example, one unit indicates 1/20000 seconds. The vertical axis indicates the vibration speed as a voltage value (V).

  The time history waveform by the laser vibrometer 30 shown in FIG. 5A shows a composite waveform in which the fast motion of the washer W is included in the large vibration of the washer W. It can be seen that the vibrations of both the fastening body P and the washer W are measured.

  On the other hand, the time history waveform by the pickup 20 shown in FIG. 5 (b) shows only the vibration waveform of the fastened body P, and the period coincides with the fine movement waveform in the composite waveform shown in FIG. 5 (a). I understand.

  As a supplementary description, when the washer W is an aluminum washer other than an iron washer, a washer made of general carbon steel, or a plastic washer, the specific gravity is different from each other. The size of the vertical axis etc.) changes. Further, even when the vibration applied by the vibrator 10 is not a sine wave vibration but a square wave vibration, the vibration mode changes. In the case of square wave vibration, the number of fine movements is smaller than that of the time history waveform shown in FIGS. 5A and 5B. For example, a simpler case where a large number of fine movements are filtered from the time history waveform shown in FIG. A waveform tends to be obtained.

  Returning to FIG. 4, next, in step S606, frequency component conversion of the fastened object P and the washer W is performed (washer frequency specifying step). Specifically, each time history is converted by applying each time history waveform (data) shown in FIGS. 5A and 5B to the FFT program stored in the frequency component conversion unit 512 to convert the frequency components. Decompose the waveform into frequency components. Here, an example of the frequency spectrum which frequency-converted the measurement data by each vibrometer is shown. FIG. 6 is a frequency spectrum obtained by frequency-converting the measurement data obtained by the vibrometer when the tightening torque is 2.5 Nm. FIG. 6A is a frequency spectrum of the measurement data obtained by the laser vibrometer, and FIG. Is the frequency spectrum of the measurement data from the pickup. Further, FIG. 7 shows a frequency spectrum obtained by frequency-converting the measurement data obtained by the vibrometer when another tightening torque is changed to 12.5 Nm. As in FIG. 6, FIG. 7A shows a frequency spectrum of measurement data obtained by a laser vibrometer, and FIG. 7B shows a frequency spectrum of measurement data obtained by a pickup.

  Here, in step S602, the vibrator 10 is vibrated at 1000 Hz, and the results are shown in FIGS. In FIGS. 6 and 7, it is known from experience that the low vibration band of less than 1000 Hz does not correspond to any vibration band of the fastened body P and the washer W. Therefore, the spectrum peak below 1000 Hz is I will ignore it. Furthermore, since it is known from experience that the frequency band of the washer W is 5000 Hz or higher, the frequency band of less than 5000 Hz is ignored in specifying the frequency of the washer W.

  Referring to FIGS. 6A and 6B, there is a spectrum peak at 1000 Hz in both cases, which is the frequency of the fastened object P due to the vibration of the vibrator 10 at 1000 Hz. On the other hand, in the frequency spectrum of the measurement data obtained by the laser vibrometer shown in FIG. 6A, there is a spectrum peak at 6200 Hz. On the other hand, in the frequency spectrum of the measurement data obtained by the pickup shown in FIG. There is no spectral peak in the frequency band. Therefore, in step S608 in FIG. 4, the spectrum peak 6200 Hz in FIG. 6A is specified as the frequency of the washer W when the tightening torque is 2.5 Nm from both frequency spectra.

  Here, for reference, a result at another tightening torque of 12.5 Nm is shown with reference to FIGS. From FIGS. 7 (a) and 7 (b), a spectrum peak exists at 1000 Hz as in FIGS. 6 (a) and 6 (b). In the frequency spectrum of the measurement data obtained by the laser vibrometer shown in FIG. 7A, a spectrum peak exists at 6600 Hz, so that the spectrum peak 6600 Hz in FIG. Is specified as the frequency of the washer W.

  Returning to FIG. 4, when the frequency of the washer W when the tightening torque is 2.5 Nm is specified in step S608, the process returns to step S600 and the tightening torque is changed to, for example, 5 Nm and reset, and thereafter steps S602 to S602 are performed. S608 is executed. In the flow in which the tightening torque is set to 12.5 Nm, as already described with reference to FIG. 7, 6600 Hz is specified as the frequency of the washer W when the tightening torque is 12.5 Nm.

  By performing steps S602 to S608 in FIG. 4 while varying the tightening torque, in step S610, the relationship data between the tightening torque of the tightening bolt B and the frequency of the washer W is specified (relation data specifying step). Here, FIG. 8 is a diagram illustrating an example of a relationship graph between the tightening torque and the washer frequency. This relationship graph is an example of a relationship graph relating to an iron washer corresponding to the M10 tightening bolt. In this case, each plot relating to the frequency of the washer W for each tightening torque specified in the flow shown in FIG. 4 can be approximated by a linear function. Depending on the tendency of each plot, a relationship graph may be created as a curve graph such as a quadratic function. When the relation data (relation graph) shown in FIG. 8 is created, the flow until the relation data in the test room in FIG. 4 is specified is completed.

  The relational data created here is stored in the computer 50 shown in FIG. When specifying the actual tightening torque of the tightening bolt B in the existing structure, the measurer brings the tightening torque specifying device 100 including the computer 50 to the site and specifies the tightening torque. Specifically, a specifying method based on the flow shown in the lower part of FIG. 4 is executed.

  In step S <b> 700, vibration of a predetermined frequency band is generated by the vibrator 10 to vibrate the fastened body P of the existing structure. In step S <b> 702, the vibration speed of the fastened body P is measured by the pickup 20, and the vibration speed of the washer W is measured by the laser vibrometer 30. Next, in step S704, the frequency components of the fastened object P and the washer W are converted, and in step S706, the frequency of the washer W is specified.

  In step S708, by applying the frequency of the specified washer W to the relational data stored in the computer 50, in step S710, the tightening torque of the tightening bolt B to be measured is specified (tightening torque specifying step). ).

  According to the tightening torque specifying method according to the present embodiment, when the tightening torque of the tightening bolt B in the to-be-fastened body P of the existing structure is specified, the tightening torque is not directly in contact with the tightening bolt B. It is possible to specify the tightening torque of the tightening bolt B.

[Second Embodiment]
<Tightening torque identification device>
Next, a tightening torque specifying device according to the second embodiment of the present invention will be described with reference to FIG. FIG. 9 is a diagram illustrating an example of a tightening torque specifying device according to the second embodiment. The tightening torque specifying device 200 is configured by sticking the piezoelectric element 60 as a vibrometer on the surface of the washer W instead of the laser vibrometer 30 in the tightening torque specifying device 100. Further, since the piezoelectric element 60 has too high resistance, it is connected to the A / D converter 43 via the impedance converter 44. The other device configuration is the same as that of the tightening torque specifying device 100.

  The piezo film 60 is an ultralight film made of PVDF (Poly Vinylidene DiFluoride), which is a plastic having a piezoelectric effect. Therefore, even if the piezo film 60 is attached to the surface of the washer W, there is almost no increase in weight. Therefore, when the fastened body P vibrates, vibration of only the washer W can be generated.

  Further, since the tightening torque specifying device 200 has a configuration in which the piezo film 60 is attached to the surface of the washer W, the tightening torque specifying device 200 is more specific than the tightening torque specifying device 100 when specifying the tightening torque of the tightening bolt B of the existing structure. It is a more practical device because it is easy to transport to the site and has good measurements at the site. The tightening torque specifying device 200 also has the hardware configuration shown in FIG. 2 and the functional configuration shown in FIG.

[Verification of the influence of the frequency band by the vibrator on the relational data of tightening torque and washer frequency]
The present inventors have verified whether or not the frequency band due to the vibrator affects the relationship data between the tightening torque and the washer frequency. In this verification, a test device was created using an iron washer for M10 tightening bolts, the frequency of vibration generated by the vibrator was changed from 1 kHz to 10 kHz every 1 kHz, and vibrations in each frequency band were tested. By applying the tightening torque specifying method shown in FIG. 4 to the object to be fastened, the relationship graph between the tightening torque and the washer frequency in the vibration of each frequency band was specified. FIG. 10 shows the verification result.

  From FIG. 10, it is verified that even if the frequency by the vibrator is changed between 1 kHz and 10 kHz, the same relationship graph between the tightening torque and the washer frequency is specified. Further, since the standard tightening torque of the M10 tightening bolt is 24.5 Nm, it can be seen that the frequency of the washer is about 7000 Hz in the torque range below the standard tightening torque. Therefore, it is considered that the detection accuracy of the tightening torque can be further improved by adjusting the device configuration so that the washer itself resonates in a frequency band of about 7000 Hz.

  In addition, other embodiments in which other components are combined with the configurations described in the above embodiments may be used, and the present invention is not limited to the configurations shown here. . This point can be changed without departing from the spirit of the present invention, and can be appropriately determined according to the application form.

  For example, according to the washer attached with the piezo film, the vibration of only the washer can be measured without being affected by the piezo film, as described in the tightening torque specifying device according to the second embodiment. Accordingly, a washer suitable for application to the tightening torque specifying device according to the second embodiment can be provided. This washer is a washer for a fastening bolt in which a body to be fastened is fastened with a nut via a washer, and a piezoelectric element is attached as a vibrometer. When this washer for vibration detection is used together with a fastening bolt, the tightening torque decreases due to loosening of the bolt and nut, and detects a vibration change when the vibration changes. Based on the detected vibration change, the bolt tightening state can be specified and managed.

  This washer can be used, for example, at a bolt tightening position of an instrument disposed in the upper part of the tunnel, a bolt tightening position on a bridge or the like. By continuously measuring vibration using a vibration detection washer, it is possible to instantly detect that some abnormality has occurred at the time of detecting a vibration change, which is extremely useful. In other words, normally occurring vibrations (for example, vibrations caused by traffic of the vehicle, etc.) are measured via the washer, and this measurement is continuously performed, so that abnormality occurs when the tightening torque changes. It becomes possible to identify the matter instantly.

  10: Vibrator (vibration means), 20: pickup, 30: laser vibrometer (laser Doppler vibrometer), 50: computer, 60: piezoelectric element (piezo film), 100, 200: tightening torque specifying device, P : Fastened body, B: Fastening bolt, N: Nut, W: Washer

Claims (8)

A tightening torque identifying device for a tightening bolt for identifying a tightening torque of a tightening bolt whose body to be fastened is tightened with a nut via a washer,
Vibration means for vibrating the fastened body;
A vibrometer for measuring vibrations of the fastened body and the washer;
A tightening bolt, comprising: a computer storing a conversion program for converting measurement data obtained by the vibration meter into a frequency component, and storing data related to the tightening torque of the tightening bolt and the frequency of the washer. Tightening torque identification device.   The tightening bolt according to claim 1, wherein in the computer, only the frequency of the washer is specified, and the frequency of the washer is applied to the relational data to determine the tightening torque of the tightening bolt. Tightening torque identification device.   The said vibrometer is either a laser vibrometer which irradiates a laser to the said washer and acquires a reflected laser, or a piezoelectric element with which the said washer is mounted | worn, The 1st or 2 characterized by the above-mentioned The tightening torque specifying device for the specified tightening bolt. The vibrometer that measures the vibration of the fastened body and the washer is composed of a vibrometer specific to the measurement of each vibration,
The vibrometer for measuring the vibration of the fastened body comprises a pickup,
The vibrometer that measures the vibration of the washer is either a laser vibrometer that irradiates the washer with a laser to obtain a reflected laser, or a piezoelectric element that is attached to the washer. The tightening torque specifying device for a tightening bolt according to claim 1 or 2. A tightening bolt specifying method for specifying a tightening torque of a tightening bolt in which a body to be fastened is tightened with a nut via a washer,
A vibration step of vibrating the fastened body;
A vibration measuring step for measuring vibrations of the fastened body and the washer;
After converting the measurement data measured in the vibration measurement step into a frequency component, the frequency of the washer is specified, a washer frequency specifying step,
A relationship data identification step for identifying relationship data between the tightening torque of the tightening bolt and the frequency of the washer;
A tightening torque that specifies a tightening torque of the tightening bolt by applying the frequency of the washer specified in the washer frequency specifying step to the relation data specified in the related data specifying step. And a specifying step. A method for specifying a tightening torque of a tightening bolt. In the vibration measuring step,
Measurement of vibration of the fastened body and vibration of the washer by irradiating the washer with a laser to obtain a reflected laser, and measuring with the piezoelectric element by attaching a piezoelectric element to the washer The tightening bolt specifying method for a tightening bolt according to claim 5, wherein the tightening torque is determined by any one of the following methods. In the vibration measuring step,
Measure the vibration of the fastened body with a pickup,
Measurement of the vibration of the washer is performed by any one of a method of irradiating the washer with a laser to obtain a reflected laser, and a method of attaching a piezoelectric element to the washer and measuring with the piezoelectric element. The method for identifying a tightening torque of a tightening bolt according to claim 5, wherein: A washer for a fastening bolt in which a body to be fastened is fastened with a nut via a washer,
A washer with a piezoelectric element attached as a vibration meter.