JP2017015707A - Axial force measuring apparatus, axial force measuring method, ultrasonic inspection apparatus, ultrasonic inspection method and vertical probe fixture used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an axial force measuring apparatus, an axial force measuring method, an ultrasonic inspection apparatus, an ultrasonic inspection method and a vertical probe fixture used therefor in which interference frequency can be accurately measured despite a simple configuration, and conditions of a test piece including an axial force can be measured accurately more than ever.SOLUTION: A vertical probe fixture 10 matches a relative position and a relative attitude when sending/receiving a burst wave twice including sending/receiving a burst wave for creating calibration data of a vertical probe 2 for a long member 100 or sending/receiving a burst wave in an unloaded condition of the long member 100, and sending/receiving a burst wave in a loaded condition of the long member 100. A signal processing part 3 makes the burst wave incident while changing an oscillation frequency, and a signal intensity measurement part 36a measures signal intensities for respective oscillation frequencies. The maximum interference frequency which generates the maximum signal intensity within a predetermined interference frequency range is obtained from the measured signal intensities for respective oscillation frequencies, and an axial force of the long member 100 is measured based on the obtained frequency.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an axial force measuring device, an axial force measuring method, an ultrasonic inspection device, an ultrasonic inspection method, and a vertical probe fixing jig used therefor. More specifically, a probe that receives ultrasonic waves from one end of the long member and receives reflected waves reflected from the other end of the long member, an ultrasonic generator that generates the ultrasonic waves, and An axial force measuring device, an axial force measuring method, an ultrasonic inspection device, an ultrasonic inspection method, and a vertical probe used therefor, comprising a signal processing unit that processes a reflected wave signal and measures the axial force of the long member It relates to a fixture.

  Conventionally, as an axial force measurement method using ultrasonic waves as described above, for example, a method shown in Patent Document 1 is known. When an axial force is applied to the bolt, the bolt is extended, and the propagation time of the ultrasonic wave is extended due to the extension of the bolt. Therefore, in the method of Patent Document 1, an ultrasonic pulse is incident from the head of the bolt and the propagation time of the ultrasonic wave reflected and returned from the bolt end is measured, and the axial force of the bolt is measured based on this propagation time. To do. However, when the length of the bolt is short, the extension of the bolt by tightening is also shortened, and the accuracy may be lowered. There is also a risk of misreading the time due to amplitude or waveform distortion.

  As another method, there is also known a method (resonance method) in which the oscillation frequency of ultrasonic waves incident from the bolt head is swept to measure the resonance frequency corresponding to the length of the bolt. In this method, in order to detect the resonance frequency corresponding to the change in the bolt length caused by the axial force, vibration energy for maintaining the resonance state must be continuously supplied.

JP-A-5-203513

  In view of such a conventional situation, the present invention is an axial force measuring device and an axial force measuring method capable of accurately measuring an interference frequency with a simple configuration and more accurately measuring a state of a test body such as an axial force. An object of the present invention is to provide an ultrasonic inspection apparatus, an ultrasonic inspection method, and a vertical probe fixing jig used therefor.

  In order to achieve the above object, the axial force measuring device according to the present invention is characterized in that a probe that receives ultrasonic waves from one end of a long member and receives reflected waves reflected from the other end of the long member; And an ultrasonic generator for generating the ultrasonic wave, and a signal processing unit for processing a signal of the received reflected wave and measuring an axial force of the long member. A vertical probe fixing jig for fixing a relative position of the child and a relative posture of the vertical probe, the ultrasonic generator generates a burst wave, and the signal processing unit oscillates A signal intensity measuring unit for measuring the signal intensity of the burst wave in a measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave for each frequency; Calibration data of the vertical probe with respect to the scale member At the time of transmission and reception of the burst wave in the unloaded state of the long member, and at the time of transmission and reception of the burst wave in the loaded state of the long member, The relative position and the relative attitude are matched, and the signal processing unit makes the burst wave incident while changing the oscillation frequency, and the signal intensity measurement unit measures the signal intensity for each oscillation frequency. Determining the maximum interference frequency that gives the maximum signal intensity within a predetermined interference frequency range from the measured signal intensity for each oscillation frequency, and measuring the axial force of the long member based on the determined maximum interference frequency. is there.

The interferometry applied to the present invention detects a change in the interference frequency of a synthetic wave that is generated when ultrasonic waves propagating through a long member interfere with each other. Here, according to the experiments by the inventors, as shown in FIG. 16, in the measurement of the interference frequency, when the relative position and the relative posture of the vertical probe with respect to the long member are matched, the variation is denoted by d1 to d1. Although it can be suppressed to the extent indicated by d4, when the angles (relative postures) are not matched, a maximum variation indicated by the symbol D is assumed. That is, it was found that the variation in measured values can be suppressed by matching the relative position and relative posture of the vertical probe with respect to the long member.
According to the above configuration, the vertical probe fixing jig for fixing the relative position of the vertical probe and the relative attitude of the vertical probe with respect to the long member is provided, and calibration data of the probe with respect to the long member is obtained. The relative position and the relative attitude are determined twice, at the time of transmission / reception of a burst wave when creating or transmitting / receiving a burst wave when the long member is unloaded, and at the time of transmission / reception of the burst wave when the long member is loaded. Since they are matched, the measurement error of the interference frequency due to the mismatch between the relative position and the relative posture of the vertical probe can be suppressed. Therefore, it is possible to measure the axial force with high accuracy with a simple configuration.

  The signal processing unit includes an unloaded maximum interference frequency at which the signal strength in the unloaded state of the axial force of the long member is maximized and a loaded maximum interference frequency at which the signal strength in the loaded state of a known axial force is maximized. An axial force calculation formula indicating a relationship between the difference and the known axial force is further included, and the axial force calculation formula is determined by the vertical probe fixing jig in the unloaded state and the loaded state. The signal strength measurement unit is created in a state where the position and the relative posture are matched, and the signal intensity measuring unit is attached to one end of a long member to which the vertical probe is fastened by the vertical probe fixing jig. The signal processing unit measures the signal intensity for each oscillation frequency in a state of being attached in accordance with the relative position and the relative posture at the time of creating the axial force calculation formula, and the signal processing unit measures the signal for each measured oscillation frequency. Interference frequency from intensity Seeking a maximum interference frequency with the maximum signal strength in the range, the maximal interfering frequencies determined the axial force calculation formula may measure the axial force of the long member.

  Thereby, the axial force calculation formula is created in a state in which the relative position and the relative posture of the probe are matched by the vertical probe fixing jig in all of the unloaded state and the loaded state, and At the time of inspection, the vertical probe is attached to one end of the long member fastened by the vertical probe fixing jig in accordance with the relative position and relative posture at the time of creating the axial force calculation formula for each oscillation frequency. In addition, since the signal intensity is measured, the measurement error of the interference frequency due to the mismatch between the relative position and the relative posture of the vertical probe can be suppressed. Therefore, it is possible to measure the axial force with high accuracy with a simple configuration.

  In addition, the signal strength measuring unit measures the signal strength in an unloaded state of the axial force of the long member for each oscillation frequency, and the vertical probe is moved by the vertical probe fixing jig. In a state in which a known axial force is applied to a long member in an unloaded state and attached to one end of the elongated member in a loaded state in accordance with the relative position and the relative posture at the time of measurement in the unloaded state Measuring the signal intensity for each oscillation frequency, and the relative position when the no-load state is measured at one end of a long member to which the vertical probe is fastened by the vertical probe fixing jig; The signal strength is measured for each oscillation frequency in a state of being attached in conformity with the relative posture, and the signal processing unit determines the maximum signal strength in the no-load state from the measured signal strength for each oscillation frequency. No-load maximum interference circumference And an axial force calculation formula indicating the relationship between the difference between the obtained no-load maximum interference frequency and the load maximum interference frequency and the known axial force. The maximum interference frequency that is the maximum signal strength within a predetermined interference frequency range is determined from the signal intensity for each oscillation frequency that has been created and measured, and the axial force of the long member is determined by the calculated maximum interference frequency and the axial force calculation formula. May be measured.

  Thus, the relative position and relative position of the probe are matched by the vertical probe fixing jig in the unloaded state and the loaded state of the axial force of the long member, and the vertical probe is The signal strength is measured at each oscillation frequency in a state where it is attached to one end of a long member fastened by a vertical probe fixing jig in accordance with the relative position and relative posture at the time of measurement in the no-load state. The measurement error of the interference frequency due to the mismatch between the relative position and the relative posture of the probe can be suppressed. Therefore, it is possible to measure the axial force with high accuracy with a simple configuration.

  The ultrasonic generator generates two types of ultrasonic waves, which are different from the burst wave and the burst wave, and the signal processing unit measures the propagation time of the different ultrasonic waves. A propagation time measurement unit, a signal intensity measurement unit for measuring the signal intensity of the burst wave in a measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency, and the above-described known axial force A first master curve for obtaining a propagation time; and a second master curve for obtaining a maximum interference frequency that maximizes the signal intensity with respect to the known axial force, wherein the second master curve is a load of the known axial force. It was created in a state where the relative position and the relative posture were matched by the vertical probe fixing jig in all the states, and the propagation time measuring unit was attached to the fastened long member The propagation time is measured by injecting different ultrasonic waves, and the signal intensity measuring unit is configured to connect the second master to one end of a long member to which the vertical probe is fastened by the vertical probe fixing jig. The signal strength is measured for each oscillation frequency in a state of being attached in accordance with the relative position and the relative posture at the time of creating the curve, and the signal processing unit measures the propagation time measured from the first master curve. The approximate axial force is obtained, the interference frequency range in the approximate axial force is obtained from the second master curve, and the maximum interference frequency that is the maximum signal strength within the interference frequency range is obtained from the measured signal strength for each oscillation frequency. The axial force of the long member may be measured based on the obtained maximum interference frequency and the second master curve.

  According to the above configuration, the signal processing unit measures the propagation time of the ultrasonic wave different from the burst wave and the measurement from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency. A signal strength measurement unit that measures the signal strength of ultrasonic waves different from burst waves in time, a first master curve that determines the propagation time for a known axial force, and a maximum interference frequency that maximizes the signal strength for a known axial force And a second master curve. Then, for example, as shown in FIG. 23, the approximate axial force F ′ at the propagation time T of the second burst wave measured from the first master curve M1 is obtained, and the interference at the approximate axial force F ′ obtained from the second master curve M2 is obtained. The frequency range fr is obtained, and the maximum interference frequency Q that provides the maximum signal strength within the interference frequency range fr obtained from the measured signal strength for each oscillation frequency is obtained. Then, the axial force of the long member is calculated from the obtained maximum interference frequency Q and the second master curve M2. In this way, since the approximate axial force is obtained from the propagation time of ultrasonic waves different from the burst wave and the interference frequency range is obtained from the approximate axial force, the maximum interference frequency of the burst wave can be predicted, and the peak value etc. Incorrect measurement can be prevented. In addition, the second master curve was created in a state where the relative position and relative orientation were matched by the vertical probe fixing jig in all known axial force loading states. The signal strength is measured for each oscillation frequency in a state where the child is attached to one end of the long member fastened by the vertical probe fixing jig in accordance with the relative position and the relative posture at the time of creating the second master curve. Therefore, it is possible to suppress the measurement error of the interference frequency due to the mismatch between the relative position and the relative posture of the vertical probe. Therefore, it is possible to measure the axial force with high accuracy with a simple configuration.

  Further, the ultrasonic generator generates two types of ultrasonic waves, which are different from the burst wave and the burst wave, and the signal processing unit measures the propagation time of the different ultrasonic waves. A propagation time measurement unit, a signal intensity measurement unit for measuring the signal intensity of the burst wave in a measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency, and the above-described known axial force A first master curve for obtaining a propagation time; and a second master curve for obtaining a maximum interference frequency that maximizes the signal intensity with respect to the known axial force, wherein the second master curve is a load of the known axial force. In all of the states, the vertical probe fixing jig is used to match the relative position and the relative posture, and the propagation time measurement unit is attached to the fastened long member. The ultrasonic wave is incident to measure the propagation time, and the signal intensity measuring unit is connected to the second master curve at one end of a long member in which the vertical probe is fastened by the vertical probe fixing jig. The signal intensity is measured for each oscillation frequency in a state where the relative position and the relative posture at the time of creation are attached, and the signal processing unit obtains the maximum interference frequency, and the second master The approximate axial force at the maximum interference frequency obtained from the curve is obtained, the propagation time range in the approximate axial force obtained from the first master curve is obtained, and the maximum signal intensity within the propagation time range from the measured propagation time and The maximum propagation time may be obtained, and the axial force of the long member may be measured based on the obtained maximum propagation time and the first master curve.

  According to the above configuration, the signal processing unit measures the propagation time of the ultrasonic wave different from the burst wave and the measurement from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency. A signal strength measurement unit that measures the signal strength of a burst wave in time, a first master curve that determines the propagation time for a known axial force, and a second master that determines the maximum interference frequency that maximizes the signal strength for a known axial force With curves. For example, as shown in FIG. 26, the approximate axial force F ′ at the maximum interference frequency Q of the burst wave obtained from the second master curve M2 is obtained, and the propagation time at the approximate axial force F ′ obtained from the first master curve M1 is obtained. A range tr is obtained, and a maximum propagation time T ′ having the maximum signal intensity within the propagation time range tr is obtained from the measured propagation time. Then, the axial force of the long member is calculated from the obtained maximum propagation time T ′ and the first master curve M1. In this way, since the approximate axial force is obtained from the maximum interference frequency of the burst wave and the propagation time range is obtained from the approximate axial force, the maximum propagation time of the ultrasonic wave different from the burst wave can be predicted, and the peak value etc. are misread. Can prevent erroneous measurement. In addition, the second master curve was created in a state where the relative position and relative orientation were matched by the vertical probe fixing jig in all known axial force loading states. The signal strength is measured for each oscillation frequency in a state where the child is attached to one end of the long member fastened by the vertical probe fixing jig in accordance with the relative position and the relative posture at the time of creating the second master curve. Therefore, it is possible to suppress the measurement error of the interference frequency due to the mismatch between the relative position and the relative posture of the vertical probe. Therefore, it is possible to measure the axial force with high accuracy with a simple configuration.

  In any one of the configurations described above, the vertical probe fixing jig has a jig azimuth indicating section that instructs the azimuth of the jig, and the long member is a long member that indicates the azimuth of the long member. It is preferable to have an azimuth indicating unit, and the vertical probe has a vertical probe azimuth indicating unit that indicates the azimuth of the vertical probe, and these indicating units are made to coincide. As a result, the relative position and the relative posture of the vertical probe can be easily made coincident with each other.

  In this case, the long member is a bolt, and the vertical probe fixing jig has a fitting portion that fits into the bolt head portion and a housing portion that accommodates the vertical probe, and the fitting The joint portion and the housing portion are preferably communicated with each other. Further, the probe orientation instruction portion may be a cable base end portion protruding in a horizontal direction from the vertical probe. The elongated member is a bolt, and the vertical probe fixing jig has a bottom surface that coincides with the top surface of the bolt head, and a storage portion that stores the vertical probe. May be provided with a magnet.

  In order to achieve the above object, the axial force measuring method according to the present invention is characterized in that an ultrasonic wave is incident from a vertical probe at one end of a long member and a reflected wave is reflected from the other end of the long member. And measuring the axial force of the elongated member based on the received reflected wave signal, the ultrasonic wave is a burst wave, and calibration data of the vertical probe with respect to the elongated member is obtained. When the burst wave is generated or transmitted twice, or when the burst wave is transmitted / received when the long member is unloaded, and when the burst wave is transmitted / received when the long member is loaded, the long wave Propagation of the reflected wave for each oscillation frequency by making the burst wave incident while changing the oscillation frequency in a state where the relative position of the vertical probe with respect to the scale member and the relative posture of the vertical probe are matched. Next anti from time The signal intensity of the burst wave during the measurement time until the wave propagation time is measured, and the maximum interference frequency that gives the maximum signal intensity within a predetermined interference frequency range is determined from the measured signal intensity for each oscillation frequency, and the maximum obtained The axial force of the long member is measured based on the interference frequency.

  In such a case, in advance, the difference between the no-load maximum interference frequency at which the signal strength in the unloaded state of the axial force of the long member is maximum and the load maximum interference frequency at which the signal strength in the loaded state of the known axial force is maximized. The relative position and the relative posture are matched by the vertical probe fixing jig in all of the unloaded state and the loaded state. The vertical probe is attached to one end of a long member fastened by the vertical probe fixing jig so as to match the relative position and the relative posture at the time of creating the axial force calculation formula. The signal intensity is measured for each oscillation frequency, the maximum interference frequency that is the maximum signal intensity within a predetermined interference frequency range is determined from the measured signal intensity for each oscillation frequency, and the calculated maximum interference frequency and the axial force are calculated. In the formula Ri may measure the axial force of the long member.

  In addition, the signal strength in the unloaded state of the axial force of the long member is measured for each oscillation frequency, and the long member in the unloaded state is connected to the vertical probe by the vertical probe fixing jig. The signal strength is set for each oscillation frequency in a state in which it is attached to one end of a long member loaded with a known axial force to match the relative position and the relative posture at the time of measurement in the no-load state. The no-load maximum interference frequency at which the maximum signal strength is obtained in the no-load state and the maximum load interference frequency at which the maximum signal strength is obtained in the load state are obtained from the measured signal strength at each oscillation frequency. An axial force calculation formula showing a relationship between a difference between a load maximum interference frequency and a load maximum interference frequency and the known axial force is created, and the vertical probe is fastened by the vertical probe fixing jig. Scale member The signal strength is measured for each oscillation frequency with the relative position and the relative attitude at the time of measurement in the no-load state being attached to an end, and a predetermined interference frequency is determined from the measured signal strength for each oscillation frequency. A maximum interference frequency that gives the maximum signal intensity within the range may be obtained, and the axial force of the long member may be measured by the obtained maximum interference frequency and the axial force calculation formula.

  The ultrasonic waves are two kinds of ultrasonic waves, which are different from the burst wave and the burst wave, and the propagation time of the reflected wave is obtained by causing the different ultrasonic waves to enter from one end of the long member in advance. And measuring the signal intensity of the burst wave in the measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave by making the burst wave incident while changing the oscillation frequency. When creating the first master curve for obtaining the propagation time with respect to the second master curve for obtaining the maximum interference frequency at which the signal intensity with respect to the known axial force is maximized, the known axial force of the long member The relative position and the relative posture are matched by the vertical probe fixing jig in all of the load conditions of the above, and the different ultrasonic waves are incident on the fastened long member to propagate the signal. And the vertical probe is attached to one end of a long member fastened by the vertical probe fixing jig so as to match the relative position and the relative posture at the time of creating the second master curve. In the state, the signal intensity was measured for each oscillation frequency, the approximate axial force in the propagation time measured from the first master curve was obtained, the interference frequency range in the approximate axial force was obtained from the second master curve, and measured. The maximum interference frequency that is the maximum signal intensity within the interference frequency range is obtained from the signal intensity for each oscillation frequency, and the axial force of the long member may be measured using the obtained maximum interference frequency and the second master curve. .

  The ultrasonic waves are two kinds of ultrasonic waves, which are different from the burst wave and the burst wave, and the propagation time of the reflected wave is obtained by causing the different ultrasonic waves to enter from one end of the long member in advance. And measuring the signal intensity of the burst wave in the measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave by making the burst wave incident while changing the oscillation frequency. When creating the first master curve for obtaining the propagation time with respect to the second master curve for obtaining the maximum interference frequency at which the signal intensity with respect to the known axial force is maximized, the known axial force of the long member The relative position and the relative posture are matched by the vertical probe fixing jig in all of the load conditions of the above, and the different ultrasonic waves are incident on the fastened long member to propagate the signal. And the vertical probe is attached to one end of a long member fastened by the vertical probe fixing jig so as to match the relative position and the relative posture at the time of creating the second master curve. The signal intensity is measured for each oscillation frequency in a state where the maximum interference frequency is obtained, the approximate axial force at the maximum interference frequency obtained from the second master curve is obtained, and the approximate axial force obtained from the first master curve is obtained. The propagation time range is determined from the measured propagation time, the maximum propagation time that is the maximum signal intensity within the propagation time range is obtained, and the axial force of the long member is determined by the obtained maximum propagation time and the first master curve. You may measure.

  In order to achieve the above object, the ultrasonic inspection apparatus according to the present invention is characterized in that a vertical probe that receives ultrasonic waves from one end of a test body and receives reflected waves reflected from the other end of the test body. And a relative position of the vertical probe with respect to the test body in a configuration comprising: an ultrasonic generator that generates the ultrasonic waves; and a signal processing unit that processes the received reflected wave signal and inspects the test body And a vertical probe fixing jig that fixes the relative posture of the vertical probe, and the signal processing unit measures from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency. A signal intensity measuring unit for measuring the signal intensity of the ultrasonic wave in time, and the vertical probe fixing jig transmits and receives the ultrasonic wave when creating calibration data of the vertical probe with respect to the test body Or no load on the specimen The relative position and the relative posture are matched in two times, at the time of transmitting / receiving the ultrasonic wave at the time of transmission / reception and at the time of transmitting / receiving the ultrasonic wave in the loaded state of the test body, and the signal processing unit A sound wave is incident while changing the oscillation frequency, the signal intensity measurement unit measures the signal intensity for each oscillation frequency, and the maximum signal intensity within a predetermined interference frequency range from the measured signal intensity for each oscillation frequency. The maximum interference frequency is obtained, and the test body is inspected based on the obtained maximum interference frequency.

  Furthermore, in order to achieve the above object, the ultrasonic inspection method according to the present invention is characterized in that an ultrasonic wave is incident from a vertical probe at one end of a test body and a reflected wave reflected from the other end of the test body is received. In the method of inspecting the specimen based on the received reflected wave signal, when the ultrasonic probe is transmitted / received when the calibration data of the vertical probe with respect to the specimen is created, or the specimen is unloaded The relative position of the vertical probe and the relative attitude of the vertical probe with respect to the test body at the time of transmitting / receiving the ultrasonic wave in the state and at the time of transmitting / receiving the ultrasonic wave in the loaded state of the test body In a state where the ultrasonic wave is made to coincide, the ultrasonic wave is incident while changing the oscillation frequency, and the signal intensity of the ultrasonic wave in the measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency Measure Seeking a maximum interference frequency with the maximum signal strength within a predetermined interference frequency range from the measured signal strength for each oscillation frequency is to inspect the specimen on the basis of the maximum interference frequency determined.

  According to the features of the axial force measuring device, the axial force measuring method, the ultrasonic inspection device, the ultrasonic inspection method, and the vertical probe fixing jig used for the axial force measuring device according to the present invention described above, it is a simple structure but accurately interferes It was possible to measure the frequency and more accurately measure the state of the specimen such as axial force.

  Other objects, configurations, and effects of the present invention will become apparent from the following embodiments of the present invention.

It is a block diagram of an axial force measuring device concerning the present invention. It is a figure explaining the measurement (interference method) of the interference frequency of a burst wave. It is a figure explaining the relationship between the propagation of the ultrasonic wave by a time difference method, and bolt length, (a) is a figure which shows the definition of a volt | bolt and its extension, (b) is a schematic diagram of a received waveform, (c) is a high speed. A conceptual diagram of sampling, (d) is a conceptual diagram of low-speed sampling. It is a figure explaining the relationship between the propagation of the ultrasonic wave by interferometry, and bolt length, (a) is an example in which a half wavelength becomes a bolt length, (b) is an example in which one wavelength is a bolt length, (c) Is an example in which 1.5 wavelength is the volt length, and (d) is a diagram schematically showing a difference in interference frequency. It is a schematic diagram explaining the directivity of an ultrasonic wave. It is a schematic diagram explaining a time difference method. It is a schematic diagram explaining an interferometry. It is a schematic diagram explaining the influence of the inclination of the probe beam and the probe position in the interferometry. It is a figure which shows a probe fixing jig, (a) is a top view of the attachment state to a bolt head, (b) is a front view of (a), (c) is a top view of a jig, (d ) Is a front view of the jig. It is a figure which shows an example of an axial force calculation formula. It is a figure explaining the difference of a no-load maximum interference frequency and a load maximum interference frequency. It is a figure which shows an example of the measurement data in the state which fixed the probe. It is a figure which shows an example of the measurement data in the state which attached / detached the probe. It is a figure which shows the probe fixing jig with respect to the bolt by a silicone impression agent. It is a figure explaining the procedure which controlled and measured the rotation angle of the probe with respect to a volt | bolt, (a) is the state which matched the instruction | indication part (0 degree), (b) is a probe from (a). (C) is a state where the probe is rotated 180 ° from (a), and (d) is a state where the probe is rotated 270 ° from (a). It is a figure which shows an example of the measurement data of FIG. FIG. 16 is a diagram corresponding to FIG. 13 in the measurement data of FIG. 15. It is a block diagram of the axial force measuring device concerning a second embodiment of the present invention. It is a figure explaining the measurement (time difference method) of the propagation time of a 2nd burst wave. It is a flowchart which shows the master curve creation procedure. (A) is a figure which shows an example of a 1st master curve, (b) is a 2nd master curve. It is a figure which shows an example of the measurement waveform in the time difference method and interference method in bolt length 160mm. It is a flowchart which shows an axial force measurement procedure. It is an example of the graph in an axial force measurement procedure, (a) is a time waveform, (b) is a 1st master curve, (c) is a 2nd master curve, (d) is an interference waveform, (e) is a 2nd master. Each curve is shown. It is a figure which shows an example of the measurement waveform in the time difference method and interference method in bolt length 30mm. It is a flowchart which shows the axial force measurement procedure which concerns on 3rd embodiment. It is an example of the graph in the axial force measurement procedure in 3rd embodiment, (a) is an interference waveform, (b) is a 2nd master curve, (c) is a 1st master curve, (d) is a time waveform, (e ) Indicates the first master curve. It is a figure which shows the example of a modification of a probe fixing jig. It is a figure which shows the other modification of a probe fixing jig. It is a figure which shows the example of a further modification of a probe fixing jig.

Next, the first embodiment of the present invention will be described in more detail with reference to FIGS.
As shown in FIG. 1, the axial force measuring device 1 according to the present invention generally receives ultrasonic waves from a head 101 of a bolt 100 as a long member (test body), and at the tip 102 of the bolt 100. A vertical probe 2 that receives the reflected wave (hereinafter abbreviated as “probe”), an ultrasonic generator 30 that generates an ultrasonic wave, and a bolt 100 that processes the received reflected wave signal. The signal processing unit 3 for measuring the axial force is provided. The signal processing unit 3 is connected to a display / input / output unit 4 configured by, for example, a personal computer (PC). For the probe 2, for example, a single-transducer type probe that also performs transmission and reception of ultrasonic waves is used. The probe 2 is attached to the bolt head 101 by a probe fixing jig 10 described later.

  As shown in FIG. 1, the signal processing unit 3 includes an ultrasonic generator 30, and generally includes a measurement unit 36, a master curve creation unit 37, and an axial force calculation unit 38. The ultrasonic generator 30 causes the probe 2 to generate the burst wave 21 via the power amplifier 31 in accordance with setting conditions of a burst wave setting unit 41 described later. The received reflected wave signal (received waveform) is sent to the measurement unit 36 via the protection circuit 32, the frequency filter 33, the A / D converter 34, and the filter 35 and is also stored in the data storage unit 39. The measurement unit 36 includes a signal intensity measurement unit 36a that measures the signal intensity of the burst wave 21 in the measurement time from the reflected wave propagation time to the next reflected wave propagation time for each oscillation frequency. The master curve creation unit 37 includes an axial force calculation formula creation unit 37a that creates an axial force calculation formula C indicating the relationship of the change amount Δf of the maximum interference frequency Q that maximizes the signal strength with respect to a known axial force (load). . Then, the axial force calculation unit 38 obtains the axial force from the measurement value of the measurement unit 36 and the axial force calculation formula C.

  The ultrasonic generator 30 generates a burst wave 21 as shown in FIG. The burst wave 21 is used to measure the interference frequency of a composite wave generated by ultrasonic waves propagating in the bolt 100 interfering with each other (interference method).

  As shown in FIG. 2A, the burst wave 21 becomes combined waves 20A and 20B by interference of incident ultrasonic waves and reflected waves propagating in the bolt 100. The burst wave 21 is incident while changing the oscillation frequency within a predetermined range and pitch. As shown in the figure, in the burst wave P2A having the oscillation frequency f1, the signal intensity of the synthesized wave 20A immediately after the second reflected echo B2 (the portion surrounded by the broken line in the figure) is the first reflected wave 22A and the second reflected wave. 23A interferes and weakens. On the other hand, in the burst wave P2B having the oscillation frequency f2, the first reflected wave 22B and the second reflected wave 23B interfere with the signal intensity of the synthesized wave 20B immediately after the second reflected echo B2 (the portion surrounded by the broken line in the figure). And become stronger. Thus, if the length of the volt | bolt 100 and the length of the integral multiple of the half wavelength of the burst wave 21 correspond in a synthetic | combination wave, the wave which interferes will become the same phase and signal strength will increase. In the present embodiment, the interference frequency that is the peak of the signal intensity is measured for each frequency within the predetermined range and pitch, and the interference waveform W as shown in FIG. 2B is generated, and the peak is maximized. Let the interference frequency be Q.

  Here, the time for generating the burst wave 21 is longer than the propagation time of the first reflected wave (first reflected echo B1) and shorter than the propagation time of the second reflected wave (second reflected echo B2). Good. If it is less than the propagation time of the first reflected wave, no interfering wave is generated and measurement is not possible. On the other hand, when the propagation time of the second reflected wave is exceeded, interference occurs in three or more waves (incident wave and first and second reflected waves) propagating in the bolt 100, and the signal intensity is discriminated by the interference. It becomes difficult.

  Furthermore, the measurement time (gate) for measuring the maximum interference frequency Q may be the time from the propagation time of the second reflected wave to the propagation time of the third reflected wave (third reflected echo B3). For example, if the transmission signal of the burst wave 21 is several volts to several hundred volts, the first reflected echo B1 is several mV to several hundred volts, and the second reflected echo B2 is about half of the first reflected echo B1. Therefore, the transmission echo becomes dominant because the amplitude difference between the transmission echo and the first reflection echo B1 is too large. Therefore, if the time from the propagation time of the first reflected wave to the propagation time of the second reflected wave is the measurement time, it is difficult to observe the interference. On the other hand, since the ultrasonic wave is attenuated every time it is repeatedly reflected, the signal intensity of the reflected wave after the third time becomes gradually weaker. Therefore, if the time from the propagation time of the reflected wave after the third time to the propagation time of the next reflected wave is the measurement time, it is difficult to observe the interference because the signal is weak. Thus, the maximum interference frequency Q can be easily and accurately detected by using the interference region between the first reflection echo B1 and the second reflection echo B2.

  As shown in FIG. 1, the display / input / output unit 4 generally includes a burst wave setting unit 41, a condition setting unit 42, a display unit 43, and a storage unit 44. The burst wave setting unit 41 is input and set with the oscillation frequency, wave number (length), oscillation frequency pitch, and the like of the burst wave 21. The condition setting unit 42 is input and set for the length of the bolt 100 and the like. The display unit 43 always displays the interference waveform W during axial force measurement, for example, and also displays the axial force and the like of the measurement result. The storage unit 44 stores an axial force calculation formula C, and the axial force calculation unit 38 refers to it.

  By the way, the length (axial length) of the bolt 100 as the long member is preferably 5 mm or more and 300 mm or less. For example, as shown in FIG. 3A, when the length of the bolt 100 before the axial force load is L and the length of the bolt 100 ′ after the axial force load is L + ΔL, the elongation (strain ε) is ΔL / L. Can be defined. Here, assuming 1000 με as a general elastic deformation range, elongation (strain ε) = 0.001. If the length of the bolt 100 is 5 mm, the length of the bolt 100 ′ is 5.005 mm.

  The propagation time t during which the ultrasonic wave having a propagation speed of 5.9 mm / μs reciprocates through the bolt 100 is t = 5 mm × 2 (reciprocal path) ÷ 5.9 mm / μs = 1.6949 ms. On the other hand, the propagation time t ′ in the bolt 100 ′ is t ′ = 5.005 mm × 2 (reciprocating path) ÷ 5.9 mm / μs = 1.6966 ms. The difference Δt is Δt = t′−t = 0.717 μs = 1.7 ns (FIG. 3B). The shorter the bolt length, the shorter the time difference Δt.

  When digital processing is performed on such a received signal (waveform), the sound pressure is converted into digital data at regular intervals (sampling frequency). As shown in FIG. 3C, the high-speed sampling A / D converter has a short sampling period and can identify a minute time difference, but the apparatus becomes expensive. On the other hand, as shown in FIG. 4D, the low-speed sampling A / D converter has a long sampling period and it is difficult to identify a minute time difference, but the apparatus is inexpensive. In other words, the shorter the bolt length, the shorter the sampling period is required to detect the time difference Δt. On the other hand, the time difference Δt increases as the length of the bolt increases.

  On the other hand, in the interferometry, if the general elastic deformation range is 1000 με and the length L of the bolt 100 is 300 mm, L + ΔL is 300.3 mm. Here, in the ultrasonic wave having a propagation velocity of 5.9 mm / μs, if the half wavelength is a bolt length as shown in FIG. 4A, the bolt 100 has an interference wavelength λ = 300 mm × 2 = 600 mm, an interference frequency f = 5.9 mm / μs ÷ 600 mm = 9.833 kHz. On the other hand, in the bolt 100 ′, the interference wavelength λ ′ = 300.3 mm × 2 = 600.6 mm and the interference frequency f ′ = 5.9 mm / μs ÷ 600.6 mm = 9.824 kHz. As shown in FIG. 5B, when the bolt length becomes one wavelength, the interference wavelength is reduced by half and the interference frequency is doubled. Furthermore, as shown in FIG. 5C, when the bolt length is 1.5 wavelengths, the interference wavelength is 1/3 of the half wavelength, and the interference frequency is tripled.

  Therefore, as shown in FIG. 4D, the peak of the interference intensity appears for each interference frequency. The difference in interference frequency is 9 Hz. Therefore, as the interference order (the number of half wavelengths) increases, the interference frequency increases and the difference also increases. For example, when an ultrasonic wave having an interference order of about 510 is incident on the bolt, the difference in interference frequency is 5.01 kHz, and if there is a frequency resolution of about 1 kHz, the difference in interference frequency can be detected. On the other hand, as the length of the bolt becomes longer (over 300 mm), the interference wavelength becomes longer and the interference frequency becomes smaller, so that the frequency resolution has to be improved and the apparatus becomes expensive. On the other hand, if the length of the bolt is shortened, the difference in interference frequency is also increased.

  In this way, particularly when the length of the bolt 100 is 5 mm or more and 300 mm or less, an axial force can be obtained with high accuracy using an inexpensive device without using an oscilloscope, an A / D converter having a short sampling period, or a device with high frequency resolution. Can be measured.

Here, the interference method will be further described in detail.
The ultrasonic beam B transmitted from the vertical ultrasonic probe has directivity, and the sound pressure (signal intensity) is maximized at the center Ba of the ultrasonic beam B. As shown in FIG. 5, the ideal probe 200 has the beam center Ba perpendicular to the specimen N. However, in reality, like the probes 201 and 202, the ultrasonic beam B seems to have an inclination G (an inclination of the center Ba with respect to the shortest path V (perpendicular)).

  Here, the so-called time difference method (pulse reflection method) detects a change in the propagation time T of the ultrasonic signal (bottom surface signal) R propagated through the test body N. In the ideal probe 200 shown in FIG. 6A, the beam center Ba coincides with the shortest path V. On the other hand, in the probes 201 and 202 shown in FIGS. 5B and 5C, the center Ba and the shortest path V do not coincide with each other due to the inclination G of the beam B. However, since the beam B propagates with spread, the signal R ′ propagated through the shortest path V is always received, although the center Ba shifts from the shortest path V and the intensity becomes weak. Further, since the shortest path V and the sound speed do not change, the propagation time T does not change. That is, in the time difference method, the influence of the inclination of the ultrasonic beam B and the change in the probe position on the inspection accuracy is considered to be extremely small.

  On the other hand, the so-called interferometry detects a change in the interference frequency of a composite wave generated by ultrasonic waves propagating through the specimen N interfering with each other. The ultrasonic wave propagating through the center Ba of the beam having the maximum sound pressure has the most influence on the interference. In the ideal probe 200 shown in FIG. 7A, the beam center Ba coincides with the shortest path V, and the signal of the path becomes maximum. On the other hand, in the probe 203 shown in FIG. 5B, the beam center Ba and the shortest path V do not coincide with each other, and the signal of the path of the center Ba having the inclination G becomes maximum. Therefore, the interference waveforms W1 and W2 do not match.

  The received signal (interference waveform) is a combination of the ultrasonic waves of each path. In the probe 200 having no inclination G shown in FIG. 8A, the path P1 is the shortest path V and the center Ba. Therefore, the interference waveform W3 is most affected by the ultrasonic wave of the path P1. On the other hand, in the probe 201 having the inclination G shown in FIG. 5B, the path P2 is the center Ba and the path P1 is the shortest path V. Therefore, the interference waveform W4 is most affected by the ultrasonic wave of the path P2. Furthermore, in the probe 202 located at the end of the test body N shown in FIG. 5C, the path P1 and the path P2 are the same as in FIG. 5B, but the signal of the path P3 reaches the end directly. do not do. Therefore, the interference waveform W5 is different from the previous waveforms W3 and W4 because the received signals are different. That is, in the interferometry, since the beam inclination G and position affect the maximum interference frequency Q, the inspection accuracy may be lowered. In other words, the inspection accuracy can be improved by suppressing variations due to the inclination G and position of the beam.

  Therefore, in the present invention, when placing the probe 2 on the head 101 of the bolt 100 as a long member, when transmitting / receiving ultrasonic waves when creating calibration data of the probe 2 or a long member The relative position of the probe 2 with respect to the long member 100 and the position of the probe 2 are two times, at the time of transmission / reception of ultrasonic waves in the unloaded state of 100 and at the time of transmission / reception of ultrasonic waves in the loaded state of the long member 100. Match the relative posture. Here, the relative position refers to the position of the probe on the probe placement surface (for example, the head 101) of the long member 100. The relative posture includes the inclination and rotation angle (azimuth) of the ultrasonic beam of the probe 2 with respect to the axial direction of the long member 100.

  In this embodiment, a vertical probe fixing jig 10 as shown in FIG. 9 is used. This jig 10 has a through-hole 12 that accommodates and holds the probe 2 in a substantially cylindrical main body 11 and a recess 13 that matches (fits) the hexagonal shape of the bolt 101. 13 communicates. In the vicinity of the through hole 12 on the surface of the main body 11, a jig orientation instructing section M <b> 1 that indicates the orientation of the jig 10 is provided. The jig orientation instruction unit M1 is, for example, a mark or inscription written with a pen or the like. On the other hand, a probe orientation indicating unit M2 configured similarly is also provided on the upper surface of the probe 2, and a test specimen orientation indicating unit M3 similarly configured is also provided on the upper surface of the bolt head 101. Yes. By matching these azimuth directions M1 to M3, the relative position and the relative posture of the probe 2 with respect to the bolt 100 are maintained.

Here, the axial force measurement procedure by the interferometry in this embodiment will be described.
First, the test body orientation instructing part M3 on the surface of the bolt head 101 to be inspected and the jig orientation instructing part M1 on the surface of the jig body 11 are combined, and the recess 13 of the jig 10 and the bolt head 101 are fitted. And attach. Further, the jig orientation instruction section M1 and the probe orientation instruction section M2 are aligned. By matching the azimuth indicating units M1 to M3 through the jig 10, the relative position and relative posture of the probe 2 with respect to the bolt 100 at the time of reflected wave measurement are fixed. A contact medium such as machine oil is applied to the contact surface between the probe 2 and the bolt 100.

  Next, a plurality of load conditions including no load (for example, no load, 15 kN load, 45 kN load and 60 kN load) are applied to the bolt 100, and calibration data is collected at that time, for example, an axial force as shown in FIG. A calculation formula C (calibration curve) is created. At the time of data collection, the ultrasonic generator 30 generates the burst wave 21 while changing the frequency in the probe 2 in accordance with the conditions set in the burst wave setting unit 41, and receives the reflected signal. The signal intensity is collected at the gate (measurement time) set by the signal intensity measuring unit 36a, and the relationship between the frequency and the collected signal intensity is generated as an interference waveform W, and the maximum interference frequency at which the signal intensity is maximum in the interference waveform W. Q is calculated. Then, as shown in FIG. 11, the axial force calculation formula creation unit 37a calculates the difference (change amount Δf) between the maximum interference frequency in the known load state and the maximum interference frequency in the no-load state, and is illustrated in FIG. An axial force calculation formula C is obtained. As shown in the figure, the axial force (load) and the change amount Δf have a relationship close to linear. The created axial force calculation formula C is stored in the storage unit 44 of the display / input / output unit 4.

  When the axial force measurement is performed with the bolt at the time of calibration after the calibration is completed, the bolt 100 used for the calibration is fastened at the measurement location, but under the no-load condition before the axial force measurement (or after the axial force measurement). In the same manner as above, the probe 2 is attached to the bolt head 101 with the jig 10 so that the orientations of the specimen orientation notation M3, the jig orientation notation M1, and the probe orientation notation M2 match. Collect unloaded axial force data.

  When the bolts are fastened, the jig 10 or the like becomes an obstacle to fastening. Therefore, the jig 10 or the like is temporarily removed and fastened using a fastener such as a torque wrench. When the predetermined fastening condition for measuring the axial force is reached, the fastener is removed, and the bolt 10 is again probed by the jig 10 so that the orientations of the orientation indicating parts M1 to M3 coincide with each other in the same manner as described above. A child 2 is attached and axial force data is collected. As a result, the relative position and the relative posture of the probe 2 with respect to the bolt 100 are measured twice, at the time of transmission / reception of ultrasonic waves when creating an axial force calculation formula as calibration data and at the time of transmission / reception of ultrasonic waves in a loaded state. Can be matched. In addition, as needed, you may repeat a clamp | tightening by a fastener and may measure each time. Then, the measured amount of change Δf in the maximum interference frequency is introduced into the axial force calculation formula C obtained earlier to calculate the axial force.

  Here, even when the axial force measurement is performed with a bolt different from the bolt at the time of verification, the measurement method is the same as described above. The specimen orientation indicator M3 used at the time of verification is different because the bolts are different, but the specimen orientation indicator M3 is uniquely determined by the bolt, and the relative position of the bolt 100, the jig 10, and the probe 2 is determined. In addition, the above measurement is performed so that the rotation angle does not change. As a result, the relative position and the relative posture of the probe 2 with respect to the bolt 100 can be made to coincide with each other two times at the time of transmission / reception of the ultrasonic wave in the unloaded state and at the time of transmission / reception of the ultrasonic wave in the loaded state.

Here, the inventors conducted an experiment according to the following procedure in order to verify the usefulness of the axial force measuring method and the axial force measuring device according to the present invention.
(1) Collection of calibration data The probe 2 was installed on the head 101 of the specified bolt 100, and the probe position where the bottom surface reflected signal intensity was maximum was searched. At that position, the probe 2 was fixed, and the interference frequency peak (maximum interference frequency) was measured under no load conditions and predetermined load conditions (measured at no load, 15 kN load, 45 kN load, and 60 kN load). Then, a graph of differential frequency (change amount Δf) versus load with respect to the interference frequency peak in the no-load state was created and used as an evaluation diagram (axial force calculation formula C).

(2) Measurement with the probe fixed. At the probe position and probe rotation angle at the time of calibration data collection, load was applied to the bolt 100 with no load → 15 kN load → 45 kN load → 60 kN load. Interference frequency peaks were acquired (Figure 12 legend A1). Further, after returning the probe 2 to the no-load state with the probe 2 fixed, the interference frequency peak was repeatedly acquired while applying the load in the same manner with the probe 2 fixed (FIG. 12 legends A2 and A3).
When the probe 2 is fixed, the reproducibility of the interference frequency peak is remarkably high even if the measurement is repeated many times. This indicates that the axial force can be accurately measured by measuring the interference frequency peak of the bolt 100 loaded with an unknown load.

(3) Measurement when the probe is attached / detached With the bolt 100 unloaded, the probe 2 is once attached / detached from the bolt 100 to find a probe position where the bottom surface reflected signal intensity is maximum. Thereafter, while the position of the probe 2 was fixed, no load → 15 kN load → 45 kN load → 60 kN load and a load was applied to the bolt 100, and an interference frequency peak was obtained each time (FIG. 13 legend A). In addition, each time after returning to the no-load state, the probe 2 is once removed from the bolt 100, and after searching for the probe position where the bottom surface reflected signal intensity is maximum, the load is applied in the same way, Frequency peaks were repeatedly acquired (Figure 13 legend B, C, D and E).
As a result, it was confirmed that the load-interference frequency peak straight line shifted when the probe 2 was removed. This means that when the axial force of the bolt 100 to which an unknown load is applied is measured, the measured axial force varies under the condition that the probe 2 is removed. Even in a no-load state, variations in the axial force measurement values occur when the probe 2 is removed.

(4) Confirmation of Influence of Probe Rotation Angle on Unloaded Bolt Here, a probe fixing jig 10 ′ made of a silicone impression agent as shown in FIG. 14 is manufactured, and the position of the probe relative to the bolt 100 is determined. Marks M1 to M3 for clarifying the orientation are described on the probe 2, the jig 10 ′, and the bolt 100, and the relative positions and angles of the bolt 100, the jig 10 ′, and the probe 2 are set. I was able to control it. Under this condition, as shown in FIG. 15, the probe 2 is rotated 90 °, 180 ° and 270 ° from the reference orientation (sensor rotation angle 0 °), and the interference frequency at the rotation angle 0 ° and each rotation angle is rotated. Peak measurement was performed. Further, the probe 2 is once removed from the bolt 100, and the probe 2 is moved 90 °, 180 ° and 270 ° from the reference direction based on the bolt 100, the jig 10 ′ and the mark of the probe 2. The routine of rotating and measuring the interference frequency peak at a rotation angle of 0 ° and at each rotation angle was repeated three times.
Here, FIG. 16 shows a graph in which the interference frequency peak f in a no-load state measured for each rotation angle is plotted. Since this measurement is carried out under no-load conditions, the bolt length originally does not change, and ideally the interference frequency peak should not change, but variations d1 to 4 occur at each angle. ing. If the angle is within the same angle, the variations d1 to d4 can be kept relatively small. However, when considering the measurement results at all angles, there may be a variation D between the minimum value at 270 ° and the maximum value at 180 °. In other words, the change in the rotation angle (azimuth) of the probe 2 (not matched with a specific orientation) indicates that the output of the axial force varies even when there is no load. By fixing the position and angle of the touch element, it is possible to reduce variations in the output of the axial force.

(5) Confirmation of the influence of the probe rotation angle on the load bolt With the bolt 100 unloaded, the probe 2 is once attached to and detached from the bolt 100, but the probe position and The rotation angle was set to the same condition. Thereafter, with the probe 2 fixed, no load → 15 kN load → 45 kN load → 60 kN load and a load was applied to the bolt 100, and an interference frequency peak was obtained each time (FIG. 17 legend A). Each time after returning to the no-load state, the probe 2 is once attached / detached from the bolt 100, but the load is similarly applied after setting the probe position and the rotation angle to the same conditions using the jig 10 ′. The interference frequency peak was repeatedly acquired while adding (Fig. 16 legend B, C, D and E).
As a result, unlike FIG. 13 in which the probe 2 was set using only the signal intensity as a guideline, it was confirmed that the variation in interference frequency peak was significantly reduced. This means that when the axial force of the bolt 100 to which an unknown load is applied is measured, the probe position and the rotation angle can be made the same even if the probe 2 is removed. This means that variations in measured axial force values can be reduced, and variations in measured axial force values can be reduced even in a no-load state. In this way, by matching the relative position of the probe and the relative posture of the probe with respect to the long member by two times at the time of calibration or measurement in the unloaded state and at the time of measurement in the loaded state, Variations in measurement data can be suppressed.

  In the experiment, the jig 10 ′ was made of a silicon impression agent, but the above-described jig 10 can also be used. Further, in the above experiment, the probe position where the bottom surface reflected signal intensity is maximized was found, and the position was not changed. However, the relative position of the probe only needs to match the position of the probe 2 at the time of the above two transmissions / receptions. For example, the center of the bolt 100 may be matched as the probe position. .

  In addition, in conventional vertical inspection such as inspection of internal flaws, adjustment (calibration) of the device is performed before flaw detection so that the response (reflection signal amplitude) from the reflection source of the same size is the same. As a result, the tilt of the ultrasonic beam does not become a problem. For this reason, in the conventional method of use, “change in the relative attitude of the probe (beam tilt and rotation angle (orientation))” is not normally considered as a problem. Not done. Therefore, “fixing the relative posture” is a matter that cannot be assumed in the conventional method of using the vertical probe.

  In the interference method, it is possible to measure a change in the length of the bolt 100 from the peak of the interference frequency of the ultrasonic wave according to the bolt length, and it can be converted into an axial force. In this measurement, the variation in the measurement data was small in the case of a long and narrow bolt, and the measurement data tended to vary in the case of a thick and short bolt. In this experiment, it was found that by fixing the relative position of the bolt 100 and the probe 2 and the relative angle (rotation angle) of the probe 2, variation in measurement data can be reduced even with a thick and short bolt. In addition, since there is not a small possibility that it is caused by the inclination of the ultrasonic beam unique to the probe, it is possible to further suppress variation in data by matching the posture of the probe 2.

Next, a second embodiment of the present invention will be described. In the following embodiments, members similar to those in the above embodiment are denoted by the same reference numerals.
In the second embodiment, as shown in FIG. 18, the measurement unit 36 includes a signal intensity measurement unit 36 a and a propagation time measurement unit 36 b that measures the propagation time of the second burst wave 60 different from the previous burst wave 21. . The master curve creation unit 37 has a first master curve creation unit 37b for creating a first master curve M1 for obtaining a propagation time for a known axial force (load), and a signal strength for the known axial force (load) is the maximum. A second master curve creation unit 37c for creating a second master curve M2 for obtaining a maximum interference frequency. Then, the axial force calculation unit 38 obtains the axial force from the measurement value of the measurement unit 36 and the first and second master curves M1 and M2 created in advance.

  The ultrasonic generator 30 generates two types of burst waves, the first burst wave 21 and a second burst wave 60 as an ultrasonic wave different from the burst wave 21. The second burst wave 60 is used to measure the propagation time of the ultrasonic wave propagating through the bolt 100 (time difference method). That is, in the present embodiment, two types of burst waves are generated by one ultrasonic generator 30 and two types of methods are used, and the axial force is accurately measured by using values obtained by these methods. .

  As shown in FIG. 19A, the second burst wave 60 may have a wave number shorter than the arrival time of the first reflected wave (B1: first reflected echo) by 0.5 wave or more. When the wave number is less than 0.5 waves, the generation efficiency of burst waves (ultrasonic waves) decreases. On the other hand, if the wave number is longer than the arrival time of the first reflected wave, the first reflected echo B1 overlaps with the second burst wave 60 (incident wave), making it difficult to measure the propagation time. In the present embodiment, the time difference T between the transmission echo 60 ′ (S) of the second burst wave 60 and the first reflection echo 61 ′ (B1) shown in FIG. A time waveform W ′ as shown in b) is generated.

Next, an axial force measurement procedure will be described with reference to FIGS.
As shown in FIG. 20, first and second master curves M1 and M2 are created using a test bolt having the same configuration as that of the target bolt before the axial force measurement. First, a test bolt is set on a tensile tester or a hydraulic jack, and a predetermined axial force is generated by pulling the test bolt. Further, the oscillation frequency, wave number, and oscillation frequency interval of the burst wave 21 and the second burst wave 60 incident on the burst wave setting unit 41 are input, and the length of the test bolt and the set axial force are input to the condition setting unit 42 ( S1). Next, the ultrasonic generator 30 generates the second burst wave 60 in the probe 2 according to the conditions set in the burst wave setting unit 41, and receives the reflected signal (S2). When the creation of the waveform data is completed in the propagation time measurement unit 36b (S3), the ultrasonic generator 30 causes the probe 2 to generate the burst wave 21 according to the conditions set in the burst wave setting unit 41, The reflected signal is received, and the waveform data is generated by the signal intensity measuring unit 36a (S4). At the time of transmission / reception of the burst wave 21, the relative position and the relative posture of the probe 2 with respect to the bolt 100 at the time of measurement are fixed by matching the azimuth indicating units M1 to M3 with the jig 10 described above. Thereby, the dispersion | variation in a measured value is suppressed.

  If all measurements are not completed (S5), the axial force is changed (S7) and the above steps are repeated. If the measurement is completed with each axial force (S5), the first master curve creating unit 37a determines the propagation time of the second burst wave 60 measured by the propagation time measuring unit 36b and the set axial force from FIG. A first master curve M1 is created (S6). The second master curve creation unit 37b creates a second master curve M2 as shown in FIG. 21B from the maximum interference frequency of the burst wave 21 measured by the signal intensity measurement unit 36a and the set axial force (S6). . The created first and second master curves M 1 and M 2 are stored in the storage unit 44 of the display / input / output unit 4. Then, after the first and second master curves M1 and M2 are created, axial force measurement is performed.

  Here, for example, as shown in FIG. 22, when the bolt 100 is relatively long, it is easy to specify the propagation time from the peak signal in the time waveform (second burst wave). On the other hand, since there are a plurality of peak signals in the interference waveform (burst wave), it is difficult to specify the frequency that becomes the maximum interference frequency.

  Therefore, as shown in FIG. 23, first, the oscillation frequency, the wave number, and the oscillation frequency interval of the burst wave 21 and the second burst wave 60 incident on the burst wave setting unit 41 are input and the condition setting unit 42 is input as described above. The length of the bolt 100 is input (S10). For example, an oscillation frequency of 5 MHz (for example, a variable range of 5.0 MHz to 5.1 MHz), a wave number 1 of the second burst wave 60, a wave number 600 of the burst wave 21, an oscillation frequency interval of 1 kHz, and a length of the bolt 100 of 160 mm are input. Next, the ultrasonic generator 30 generates the second burst wave 60 and receives the reflected signal (S11). Then, the propagation time measuring unit 36b generates a time waveform W ′ and measures the peak time as the propagation time T (S12, FIG. 24A).

  After measuring the propagation time T, the axial force calculation unit 38 obtains the approximate axial force F ′ at the propagation time T measured from the first master curve M1, and stores it in the condition setting unit 42. Further, the axial force calculation unit 38 obtains the interference frequency range fr in the approximate axial force F ′ from the second master curve M2 (S13, FIGS. 24B and 24C). In the present embodiment, the interference frequency range fr is set to about 10 kHz. However, the interference frequency range fr is only an example, and is set in an appropriate numerical range.

  If the approximate axial force F ′ and the interference frequency range fr can be calculated (S14), the burst wave 21 is generated while changing the frequency at the frequency interval set within the oscillation frequency range set by the ultrasonic generator 30, and reflected. A signal is received (S15). At this time, the reflected wave is received by the above-described jig 10 in a state where the probe 2 is attached in accordance with the relative position and the relative posture of the probe when the second master curve M2 is created. Then, the signal intensity measuring unit 36a generates the interference waveform W and obtains the maximum interference frequency Q from the interference frequency range fr obtained previously in the interference waveform W (S16, FIG. 24 (d)). Then, the axial force calculator 38 calculates the axial force F by substituting the obtained maximum interference frequency Q into the second master curve M2 (S17, FIG. 24 (e)). Thus, by predicting the frequency range fr in which the maximum interference frequency Q of the burst wave 21 can appear first using the second burst wave 60, the maximum interference frequency Q can be accurately calculated without misunderstanding. Without using an expensive apparatus with high frequency resolution as described above, the axial force can be measured with high accuracy using an inexpensive apparatus. Moreover, since the relative position and relative orientation of the probe are the same when creating the second master curve and when inspecting (when calculating the axial force), the measurement error of the interference frequency due to the mismatch of the relative position and relative orientation of the vertical probe Can be suppressed.

Next, a third embodiment of the present invention will be described.
In the second embodiment, the approximate axial force F ′ is first calculated from the propagation time T of the second burst wave 60, and the interference frequency range fr is obtained from the second master curve M2 based on the approximate axial force F ′. However, the burst force 21 is first applied, the approximate axial force F ′ is calculated from the maximum interference frequency Q, the propagation time range tr is obtained from the first master curve M1 based on the approximate axial force F ′, and the axial force F is obtained. It is also possible.

  For example, as shown in FIG. 25, when the bolt 100 is relatively short, it is easy to specify the maximum interference frequency from the peak signal in the interference waveform (burst wave). On the other hand, since there are a plurality of peak signals in the time waveform (second burst wave), it is difficult to specify the propagation time.

  Therefore, as shown in FIG. 26, first, the oscillation frequency, wave number, and oscillation frequency interval of the burst wave 21 and the second burst wave 60 incident on the burst wave setting unit 41 are input and the condition setting unit 42 is input in the same manner as described above. The length of the bolt 100 is input (S20). Next, the ultrasonic generator 30 generates a burst wave 21 and receives a reflected signal (S21). At this time, the azimuth indicating units M1 to M3 are matched by the jig 10 described above, and the probe 2 is attached so as to match the relative position and relative attitude of the probe when the second master curve M2 is created. Received in the received state. Then, the signal intensity measuring unit 36a generates the interference waveform W and obtains the maximum interference frequency Q (S22, FIG. 27 (a)).

  After obtaining the maximum interference frequency Q, the axial force calculation unit 38 obtains the approximate axial force F ′ at the maximum interference frequency Q obtained from the second master curve M2, and stores it in the condition setting unit 42. Moreover, the axial force calculation part 38 calculates | requires the propagation time range tr in the general axial force F 'ahead from the 1st master curve M1 (S23, FIG.27 (b) (c)).

  If the approximate axial force F 'and the propagation time range tr can be calculated (S24), the ultrasonic generator 30 generates the second burst wave 60 and receives the reflected signal (S25). Then, the propagation time measuring unit 36b generates a time waveform W ′ and obtains a maximum propagation time T ′ from the propagation time range tr previously obtained in the time waveform W ′ (S26, FIG. 27 (d)). In the present embodiment, the propagation time range tr is set to about 0.01 μs, but is merely an example, and is set within an appropriate numerical range.

  Then, the axial force calculator 38 calculates the axial force by substituting the obtained maximum propagation time T ′ into the first master curve M1 (S27, FIG. 27 (e)). In this way, by predicting the propagation time range tr in which the maximum propagation time T ′ of the second burst wave 60 can appear using the second burst wave, the maximum propagation time T ′ can be accurately detected without mistaking it. Since it can be calculated, the axial force can be measured with high accuracy by an inexpensive apparatus without using an A / D converter having a short sampling period as described above.

Finally, the possibilities of yet another embodiment of the present invention will be described.
In the embodiment described above, the probe fixing jig 10 is provided with a through hole 12 for holding the probe 2 and a recess 13 for fitting with the bolt head 101 in a substantially cylindrical main body 11. However, the structure of the jig 10 is not limited to this. For example, as shown in FIG. 28 (a), the main body portion 11 'has the same shape as the bolt head portion 101 and is placed on the head portion 101, and a mounting hole 14 is provided for attaching a grub screw or the like for holding the probe 2. May be. Further, the shape is not limited to the hexagonal column, and may be a triangular prism shape that coincides with the head 101 on three sides as shown in FIGS.

  Furthermore, each azimuth indicating unit is not limited to a mark, a stamp, or the like. For example, as shown in FIG. 29, a probe 2 ′ in which a cable connecting unit 2a is provided in a horizontal direction is used to connect the connecting unit 2a. May be used as the probe orientation instruction unit M2. Similarly, the test body orientation instructing section M3 can also use the characteristic shape of the test body such as a bolt (for example, the manufacturer's marking or the start and end of the thread groove) as the indicating section. Further, as shown in FIG. 30, for example, the housing 2b of the probe 2 "has the same shape as the bolt head 101, and a ferrite magnet or the like is provided on the bottom 2c. The relative positions can be easily matched, and the magnets can prevent displacement and stabilize the relative posture.

  Note that these are merely examples, and the present invention is not limited to this as long as the relative positions and relative postures of the probes can be matched. For example, the relative position and the relative posture (azimuth) can be easily matched by processing the bolt head 101 to form an asymmetric shape and forming the recess 13 fitted to the jig 10. Moreover, it is good also as providing a slit and a hole in the jig | tool 10 and making another orientation instruction | indication part easy to identify. Furthermore, a test body is not restricted to a long member (bolt), For example, a plate-shaped body is applicable.

  In the second and third embodiments, the propagation time T is the time difference between the transmission echo 60 '(S) of the second burst wave 60 and the first reflection echo 61' (B1). However, the present invention is not limited to this, and may be a time difference between the first reflected echo 61 '(B1) and the second reflected echo 62' (B2), for example. Further, the peak time was measured as the propagation time T as shown in FIG. However, the propagation time is not limited to the peak time, and for example, the time obtained by another method such as zero cross time, threshold cross time, or cross-correlation method can be used as the propagation time. The same applies to the maximum propagation time T ′.

  In each of the above embodiments, as shown in FIG. 3B, the amplitude value is used as the signal intensity of the combined wave (reflected signal) of the burst wave. However, the signal intensity is not limited to the amplitude value, and an integral value (area) of amplitude or energy can also be used. Thereby, the influence of high frequency noise can be reduced.

  In the second and third embodiments, the frequency, frequency pitch, wave number, etc. of the burst wave are set and input as appropriate, and are not limited to the above numerical values. In the second and third embodiments, the signal processing unit 3 is provided with the master curve creation unit 37. However, it is not always necessary to provide the master curve creation unit 37 in the signal processing unit 3, and it may be configured to be able to refer to at least the first and second master curves M1 and M2 created in advance when measuring the axial force.

  In each of the above-described embodiments, the single-transducer type probe that also transmits and receives ultrasonic waves is used as the probe 2. However, a dual-transducer type probe may be used. However, since the two-element probe has a structure in which the ultrasonic beam B is likely to be inclined G, the one-element probe can suppress the influence on interference.

  In the second embodiment, the propagation time T is measured by the second burst wave 60 to determine the interference frequency range fr via the approximate axial force F ′, and within the set oscillation frequency range of the burst wave 21 and the interference frequency range fr. The maximum interference frequency Q was determined. However, for example, after obtaining the interference frequency range fr, the interference frequency range fr can be set as the oscillation frequency range of the burst wave 21. Thereby, since the oscillation frequency range of the burst wave 21 can be limited to a range where the maximum interference frequency Q will appear, the measurement time can be shortened and the axial force can be measured efficiently.

  In the second and third embodiments, axial force measurement was performed by generating two different types of burst waves from one ultrasonic generator 30. However, it is also possible to use a pulse wave and a burst wave instead of the second burst wave.

  INDUSTRIAL APPLICABILITY The present invention can be used as an axial force measuring device and measuring method for a fastening object such as a bolt or a screw as a long member used in, for example, automobile parts, mechanical devices, other industrial devices, equipment, plants, and the like. . It can also be used as an axial force measuring device and measuring method for other long members such as medical bolts.

  Furthermore, the present invention can be applied to an ultrasonic inspection method using an interferometry, and is not limited to axial force measurement. In the interferometry, a minute change in the propagation time of the ultrasonic wave is detected as a change in the interference frequency. Therefore, the state of the material associated with the propagation time can be measured. For example, it is possible to perform strain measurement, sound speed measurement, temperature measurement, material measurement, residual stress measurement, and the like of the specimen. Further, the present invention is not limited to the long member (bolt 100), and can be applied to, for example, thickness measurement of a plate material.

1: axial force measuring device, 2, 2 ′, 2 ″: probe, 2a: cable connection portion, 2b: housing, 2c: bottom surface (magnet), 2d: vibrator, 3: signal processing portion (device main body) 4: Display / input / output part (PC) 10, 10'10A, 10B: Probe fixing jig, 11: Main body part, 12: Through hole, 13: Recessed part, 14: Mounting hole, 20A, 20B: Synthetic wave, 21: burst wave, 22: first reflected wave (B1), 23: second reflected wave (B2), 30: ultrasonic generator, 31: power amplifier, 32: protection circuit, 33: frequency filter , 34: A / D converter, 35: filter, 36: measurement unit, 36a: signal intensity measurement unit, 36b: propagation time measurement unit, 37: master curve creation unit, 37a: axial force calculation formula creation unit, 37b: First master curve creation unit, 37c: second master curve creation unit 38: axial force calculation unit, 39: data storage unit, 41: burst wave setting unit, 42: condition setting unit, 43: display unit, 44: storage unit, 60: second burst wave (different ultrasonic waves), 61, 61 ′: first reflected wave (B1), 62, 62 ′: second reflected wave (B2) 100: bolt (long member), 101: head (one end), 102: tip (other end), 200: ideal vertical probe, 201-203: real vertical probe, B: ultrasonic beam, Ba: center, C: axial force calculation formula, F: axial force, F ′: approximate axial force, fr: interference frequency range, G: tilt, M1: jig orientation instruction section, M2: probe orientation instruction section, M3: specimen orientation instruction section, N: specimen, P1-3: path, Q: maximum interference Frequency, R, R ′: reflected signal, T: propagation time, T ′: maximum propagation time, tr: propagation time range, V: shortest path ( Line), W: interference waveform, W ': time waveform,

Claims (17)

A vertical probe that receives an ultrasonic wave from one end of the long member and receives a reflected wave reflected from the other end of the long member, an ultrasonic generator that generates the ultrasonic wave, and a received reflected wave An axial force measuring device comprising a signal processing unit that processes a signal and measures an axial force of the elongated member,
A vertical probe fixing jig for fixing the relative position of the vertical probe and the relative posture of the vertical probe with respect to the long member;
The ultrasonic generator generates a burst wave,
The signal processing unit includes a signal intensity measurement unit that measures the signal intensity of the burst wave in a measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency,
The vertical probe fixing jig transmits / receives the burst wave when transmitting / receiving the burst wave when creating calibration data of the vertical probe with respect to the long member or when the long member is unloaded. Two times at the time of transmission and reception of the burst wave in the load state of the long member, the relative position and the relative attitude are matched,
The signal processing unit makes the burst wave incident while changing the oscillation frequency, and measures the signal intensity for each oscillation frequency by the signal intensity measurement unit,
Find the maximum interference frequency that gives the maximum signal strength within the specified interference frequency range from the measured signal strength for each oscillation frequency,
An axial force measuring device that measures the axial force of the long member based on the obtained maximum interference frequency. The signal processing unit includes an unloaded maximum interference frequency at which the signal strength in the unloaded state of the axial force of the long member is maximized and a loaded maximum interference frequency at which the signal strength in the loaded state of a known axial force is maximized. An axial force calculation formula showing a relationship between the difference and the known axial force;
The axial force calculation formula is created in a state where the relative position and the relative posture are matched by the vertical probe fixing jig in all of the unloaded state and the loaded state,
The signal intensity measurement unit matches the relative position and the relative posture when the axial force calculation formula is created at one end of a long member to which the vertical probe is fastened by the vertical probe fixing jig. In the attached state, measure the signal strength for each oscillation frequency,
The signal processing unit obtains a maximum interference frequency that is the maximum signal strength within a predetermined interference frequency range from the measured signal strength for each oscillation frequency,
The axial force measuring device according to claim 1, wherein the axial force of the long member is measured based on the obtained maximum interference frequency and the axial force calculation formula. The signal strength measuring unit measures the signal strength in the state of no load of the axial force of the long member for each oscillation frequency, and the vertical probe is loaded with the no load by the vertical probe fixing jig. In a state of being attached to one end of a long member that is loaded by applying a known axial force to the long member in the state in conformity with the relative position and the relative posture at the time of measurement in the no-load state, The signal intensity is measured for each oscillation frequency, and the relative position and the relative position at the time of measurement in the no-load state are measured at one end of a long member in which the vertical probe is fastened by the vertical probe fixing jig. In the state of being attached in conformity with the posture, the signal intensity is measured for each oscillation frequency,
The signal processing unit obtains a no-load maximum interference frequency at which the maximum signal strength is obtained in the no-load state and a load maximum interference frequency at which the maximum signal strength is obtained in the load state from the measured signal strength for each oscillation frequency,
Create an axial force calculation formula showing the relationship between the difference between the obtained no-load maximum interference frequency and the load maximum interference frequency and the known axial force,
Find the maximum interference frequency that gives the maximum signal strength within the specified interference frequency range from the measured signal strength for each oscillation frequency,
The axial force measuring device according to claim 1, wherein the axial force of the long member is measured based on the obtained maximum interference frequency and the axial force calculation formula. The ultrasonic generator generates two types of ultrasonic waves, ultrasonic waves different from the burst wave and the burst wave,
The signal processing unit is a propagation time measurement unit that measures the propagation time of the different ultrasonic waves,
A signal intensity measuring unit that measures the signal intensity of the burst wave in the measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency;
A first master curve for determining the propagation time for a known axial force;
A second master curve for obtaining a maximum interference frequency at which the signal intensity with respect to the known axial force is maximized,
The second master curve is created in a state where the relative position and the relative posture are matched by the vertical probe fixing jig in all of the known axial force load states,
The propagation time measuring unit measures the propagation time by causing the different ultrasonic waves to enter the fastened long member,
The signal intensity measuring unit matches the relative position and the relative posture when the second master curve is created at one end of a long member to which the vertical probe is fastened by the vertical probe fixing jig. In the attached state, measure the signal strength for each oscillation frequency,
The signal processing unit obtains an approximate axial force at a propagation time measured from the first master curve,
Obtain the interference frequency range in the approximate axial force from the second master curve,
From the measured signal strength for each oscillation frequency, find the maximum interference frequency that is the maximum signal strength within the interference frequency range,
The axial force measuring device according to claim 1, wherein the axial force of the long member is measured by the obtained maximum interference frequency and the second master curve. The ultrasonic generator generates two types of ultrasonic waves, ultrasonic waves different from the burst wave and the burst wave,
The signal processing unit is a propagation time measurement unit that measures the propagation time of the different ultrasonic waves,
A signal intensity measuring unit that measures the signal intensity of the burst wave in the measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency;
A first master curve for determining the propagation time for a known axial force;
A second master curve for obtaining a maximum interference frequency at which the signal intensity with respect to the known axial force is maximized,
The second master curve is obtained by matching the relative position and the relative posture by the vertical probe fixing jig in all the load states of the known axial force.
The propagation time measuring unit measures the propagation time by causing the different ultrasonic waves to enter the fastened long member,
The signal intensity measuring unit matches the relative position and the relative posture when the second master curve is created at one end of a long member to which the vertical probe is fastened by the vertical probe fixing jig. In the attached state, measure the signal strength for each oscillation frequency,
The signal processing unit obtains the maximum interference frequency,
Obtain the approximate axial force at the maximum interference frequency obtained from the second master curve,
Obtain the propagation time range in the approximate axial force obtained from the first master curve,
From the measured propagation time, find the maximum propagation time that is the maximum signal strength within the propagation time range,
The axial force measuring device according to claim 1, wherein the axial force of the long member is measured based on the obtained maximum propagation time and the first master curve. The vertical probe fixing jig has a jig azimuth instructing unit for instructing the azimuth of the jig, and the long member has a long member azimuth instructing unit for instructing the azimuth of the long member, The axial force measuring device according to any one of claims 1 to 5, wherein the vertical probe has a vertical probe direction indicating unit that indicates the direction of the vertical probe, and matches these indicating units. The elongate member is a bolt, and the vertical probe fixing jig has a fitting portion that fits into the bolt head and a housing portion that houses the vertical probe, and the fitting portion; The axial force measuring device according to claim 6, wherein the accommodating portion communicates. The axial force measuring device according to claim 6 or 7, wherein the vertical probe azimuth indicating unit is a cable base end protruding in a horizontal direction from the vertical probe. The elongate member is a bolt, and the vertical probe fixing jig has a bottom surface coinciding with the top surface of the bolt head, and a housing portion for housing the vertical probe, and a magnet is disposed on the bottom surface. The axial force measuring device according to claim 6 provided. An ultrasonic wave is incident from a vertical probe at one end of the long member, a reflected wave reflected from the other end of the long member is received, and the axial force of the long member is determined based on the received reflected wave signal. An axial force measurement method for measuring,
The ultrasonic wave is a burst wave,
At the time of transmission / reception of the burst wave when creating calibration data of the vertical probe for the long member or at the time of transmission / reception of the burst wave when the long member is unloaded, and the load state of the long member The oscillation frequency of the burst wave is changed in the state in which the relative position of the vertical probe and the relative attitude of the vertical probe with respect to the elongated member are matched twice at the time of transmission / reception of the burst wave in While measuring the signal intensity of the burst wave in the measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency.
Find the maximum interference frequency that gives the maximum signal strength within the specified interference frequency range from the measured signal strength for each oscillation frequency,
An axial force measurement method for measuring an axial force of the long member based on the obtained maximum interference frequency. The difference between the no-load maximum interference frequency that maximizes the signal strength in the unloaded state of the axial force of the long member and the known maximum interference frequency that maximizes the signal strength in the loaded state of the known axial force When creating an axial force calculation formula showing the relationship with the axial force of the above, the relative position and the relative posture are matched by the vertical probe fixing jig in all of the no-load state and the load state,
The signal in a state in which the vertical probe is attached to one end of a long member fastened by the vertical probe fixing jig so as to coincide with the relative position and the relative posture when the axial force calculation formula is created. Measure the intensity for each oscillation frequency,
Find the maximum interference frequency that gives the maximum signal strength within the specified interference frequency range from the measured signal strength for each oscillation frequency,
The axial force measuring method according to claim 10, wherein the axial force of the long member is measured based on the obtained maximum interference frequency and the axial force calculation formula. The signal strength in the unloaded state of the axial force of the long member is measured for each oscillation frequency, and the vertical probe is known to the unloaded long member by the vertical probe fixing jig. The signal strength is measured for each oscillation frequency in a state in which it is attached to one end of a long member that is loaded by applying an axial force of the same to match the relative position and the relative posture at the time of measurement in the no-load state. And
From the measured signal intensity for each oscillation frequency, obtain the no-load maximum interference frequency that becomes the maximum signal strength in the no-load state and the maximum load interference frequency that gives the maximum signal strength in the load state,
Create an axial force calculation formula showing the relationship between the difference between the obtained no-load maximum interference frequency and the load maximum interference frequency and the known axial force,
The oscillation frequency in a state where the vertical probe is attached to one end of a long member fastened by the vertical probe fixing jig so as to coincide with the relative position and the relative posture at the time of measurement in the no-load state. Measure the signal strength every time,
Find the maximum interference frequency that gives the maximum signal strength within the specified interference frequency range from the measured signal strength for each oscillation frequency,
The axial force measuring method according to claim 10, wherein the axial force of the long member is measured based on the obtained maximum interference frequency and the axial force calculation formula. The ultrasonic waves are two types of ultrasonic waves, which are different from the burst wave and the burst wave,
In advance, the different ultrasonic waves are incident from one end of the long member to measure the propagation time of the reflected wave, and the burst wave is incident while changing the oscillation frequency, and the reflected wave is transmitted from the reflected wave to the next reflected wave. A first master curve for determining the propagation time with respect to a known axial force by measuring the signal intensity of the burst wave in the measurement time up to the propagation time of the maximum interference frequency at which the signal strength with respect to the known axial force is maximized When creating the second master curve to determine the relative position and the relative posture by the vertical probe fixing jig in all of the load state of the known axial force of the long member,
The different ultrasonic waves are made to enter the fastened long member to measure the propagation time, and the vertical probe is attached to one end of the long member fastened by the vertical probe fixing jig. Measure the signal intensity for each oscillation frequency with the relative position and the relative attitude at the time of creation of the master curve in a state of being attached,
Obtain the approximate axial force at the propagation time measured from the first master curve,
Obtain the interference frequency range in the approximate axial force from the second master curve,
From the measured signal strength for each oscillation frequency, find the maximum interference frequency that is the maximum signal strength within the interference frequency range,
The axial force measuring method according to claim 10, wherein the axial force of the long member is measured based on the obtained maximum interference frequency and the second master curve. The ultrasonic waves are two types of ultrasonic waves, which are different from the burst wave and the burst wave,
In advance, the different ultrasonic waves are incident from one end of the long member to measure the propagation time of the reflected wave, and the burst wave is incident while changing the oscillation frequency, and the reflected wave is transmitted from the reflected wave to the next reflected wave. A first master curve for determining the propagation time with respect to a known axial force by measuring the signal intensity of the burst wave in the measurement time up to the propagation time of the maximum interference frequency at which the signal strength with respect to the known axial force is maximized When creating the second master curve to determine the relative position and the relative posture by the vertical probe fixing jig in all of the load state of the known axial force of the long member,
The second burst wave is incident on the fastened long member to measure the propagation time, and the vertical probe is connected to one end of the long member fastened by the vertical probe fixing jig. Measure the signal intensity for each oscillation frequency in a state of being attached to match the relative position and the relative posture at the time of creating the two master curve,
Determining the maximum interference frequency;
Obtain the approximate axial force at the maximum interference frequency obtained from the second master curve,
Obtain the propagation time range in the approximate axial force obtained from the first master curve,
From the measured propagation time, find the maximum propagation time that is the maximum signal strength within the propagation time range,
The axial force measuring method according to claim 10, wherein the axial force of the long member is measured based on the obtained maximum propagation time and the first master curve. A vertical probe that receives ultrasonic waves from one end of the test body and receives reflected waves reflected from the other end of the test body, an ultrasonic generator that generates the ultrasonic waves, and a signal of the received reflected waves An ultrasonic inspection apparatus comprising a signal processing unit for processing and inspecting the specimen,
A vertical probe fixing jig for fixing the relative position of the vertical probe and the relative posture of the vertical probe with respect to the test body;
The signal processing unit includes a signal intensity measurement unit that measures the signal intensity of the ultrasonic wave in a measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency,
The vertical probe fixing jig is configured to transmit and receive the ultrasonic wave when generating calibration data of the vertical probe with respect to the test body or when transmitting and receiving the ultrasonic wave in an unloaded state of the test body. The relative position and the relative posture are matched in two times at the time of transmission / reception of the ultrasonic wave in the load state of the test body,
The signal processing unit makes the ultrasonic wave incident while changing the oscillation frequency, and measures the signal intensity for each oscillation frequency by the signal intensity measurement unit,
Find the maximum interference frequency that gives the maximum signal strength within the specified interference frequency range from the measured signal strength for each oscillation frequency,
An ultrasonic inspection apparatus for inspecting the specimen based on the obtained maximum interference frequency. An ultrasonic inspection method for receiving ultrasonic waves from a vertical probe at one end of a test body, receiving a reflected wave reflected from the other end of the test body, and inspecting the test body based on a signal of the received reflected wave Because
At the time of transmission / reception of the ultrasonic wave when creating calibration data of the vertical probe for the test body, or at the time of transmission / reception of the ultrasonic wave in the no-load state of the test body, and the ultrasonic wave in the load state of the test body The ultrasonic wave is incident while changing the oscillation frequency in a state in which the relative position of the vertical probe and the relative posture of the vertical probe with respect to the specimen are matched in two times at the time of transmitting and receiving the sound wave. For each oscillation frequency, measure the signal intensity of the ultrasonic wave in the measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave,
Find the maximum interference frequency that gives the maximum signal strength within the specified interference frequency range from the measured signal strength for each oscillation frequency,
An ultrasonic inspection method for inspecting the specimen based on the obtained maximum interference frequency. A vertical probe fixing jig used in the ultrasonic inspection method according to claim 16.