JP6764271B2 - Axial force measuring device, axial force measuring method, ultrasonic inspection device, ultrasonic inspection method and vertical probe fixing jig used for this - Google Patents

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 thereto. More specifically, the probe that receives ultrasonic waves from one end of the long member and receives the reflected waves reflected from the other end of the long member, and the ultrasonic generator that generates the ultrasonic waves received the ultrasonic waves. Axial force measuring device, axial force measuring method, ultrasonic inspection device, ultrasonic inspection method, and vertical probe used for the axial force measuring device, axial force measuring method, ultrasonic inspection device, and vertical probe provided with a signal processing unit for processing the reflected wave signal and measuring the axial force of the long member. Regarding fixing jigs.

Conventionally, as a method for measuring an axial force using ultrasonic waves as described above, for example, a method as shown in Patent Document 1 is known. When an axial force is applied to the bolt, the bolt stretches, and the propagation time of ultrasonic waves also extends due to the stretching of the bolt. Therefore, in the method of Patent Document 1, the propagation time of ultrasonic waves that are incident from the head of the bolt, reflected at the end of the bolt, and returned 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 due to tightening is also shortened, which may reduce the accuracy. In addition, there is a risk that the time may be misread due to amplitude or waveform distortion.

Further, as another method, a method of sweeping the oscillation frequency of ultrasonic waves incident from the bolt head and measuring the resonance frequency according to the length of the bolt (resonance method) is also known. In this method, vibration energy for sustaining the resonance state must be constantly supplied in order to detect the resonance frequency corresponding to the change in the bolt length caused by the axial force.

Japanese Unexamined Patent Publication No. 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 measuring the interference frequency with high accuracy and more accurately measuring the state of the test piece such as the axial force with a simple configuration. , An ultrasonic inspection device, an ultrasonic inspection method, and a vertical probe fixing jig used for the ultrasonic inspection method.

In order to achieve the above object, the feature of the axial force measuring device according to the present invention is 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. In a configuration including an ultrasonic generator that generates the ultrasonic waves and a signal processing unit that processes the received reflected wave signal and measures the axial force of the long member, the long member is a long member. The vertical probe has a vertical probe orientation indicator that indicates the orientation of the vertical probe, and has a vertical probe orientation indicator that indicates the orientation of the vertical probe. The ultrasonic generator has a vertical probe fixing jig for fixing the relative position of the tentacle and the relative posture of the vertical probe, the ultrasonic generator generates a burst wave, and the signal processing unit has a signal processing unit. The vertical probe fixing jig is provided with a signal intensity measuring unit for 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. It has a jig orientation indicator that indicates the orientation of the tool, and is used during transmission / reception of the burst wave when creating calibration data of the vertical probe for the long member or in a no-load state of the long member. The jig orientation indicator, the long member orientation indicator, and the vertical probe orientation indicator are performed twice, once when the burst wave is transmitted and received, and when the burst wave is transmitted and received under the load state of the long member. By matching the above, the relative position and the relative attitude are matched, and the signal processing unit causes the burst wave to be incident while changing the oscillation frequency, and the signal intensity measuring unit performs each of the oscillation frequencies. The signal strength is measured, the maximum interference frequency that is the maximum signal strength within a predetermined interference frequency range is obtained from the measured signal strength for each oscillation frequency, and the shaft of the long member is based on the obtained maximum interference frequency. It is to measure the force.

The interferometry applied to the present invention detects a change in the interference frequency of a synthetic wave generated by the interference of ultrasonic waves propagating in a long member with each other. Here, according to the experiments of the inventors, as shown in FIG. 16, when the relative positions and the relative postures of the vertical probes with respect to the long member are matched in the measurement of the interference frequency, the variations are represented by the symbols d1 to d1. It can be suppressed to the extent indicated by d4, but when the angles (relative postures) do not match, the variation indicated by the symbol D is assumed at the maximum. That is, it was found that the variation in the measured values can be suppressed by matching the relative position and the relative posture of the vertical probe with respect to the long member.
According to the above configuration, the long member has a long member azimuth indicating unit for instructing the orientation of the long member, and the vertical probe indicates the orientation of the vertical probe. It has a portion and has a vertical probe fixing jig for fixing the relative position of the vertical probe and the relative orientation of the vertical probe with respect to a long member. The vertical probe fixing jig has a jig orientation indicating unit for instructing the orientation of the jig, and is used when transmitting / receiving a burst wave or when creating calibration data of the probe for a long member. The jig orientation indicator, the long member orientation indicator, and the vertical probe orientation indication are performed twice, when the burst wave is transmitted and received when the member is unloaded and when the burst wave is transmitted and received when the long member is loaded. By matching the parts, the relative position and the relative orientation are matched. Therefore, since it is possible to easily and easily match the relative position and the relative posture of the vertical probe, it is possible to suppress the measurement error of the interference frequency due to the mismatch between the relative position and the relative posture. Therefore, it is possible to measure the axial force with high accuracy even with a simple configuration.

The signal processing unit has a no-load maximum interference frequency that maximizes the signal strength in the no-load state of the axial force of the long member and a load maximum interference frequency that maximizes the signal strength in the load state of the known axial force. It further has an axial force calculation formula showing the relationship between the difference and the known axial force, and the axial force calculation formula is relative to the vertical probe fixing jig in all of the no-load state and the load state. The signal strength measuring unit is created in a state where the position and the relative posture are matched, and the signal intensity measuring unit is formed by the vertical probe at one end of a long member to 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 creating the axial force calculation formula are matched, and the signal processing unit measures the signal for each measured oscillation frequency. It is preferable to obtain the maximum interference frequency that is the maximum signal strength within a predetermined interference frequency range from the intensity, and measure the axial force of the long member by the obtained maximum interference frequency and the axial force calculation formula.

As a result, the axial force calculation formula is created in a state where the relative position and the relative posture of the probe are matched by the vertical probe fixing jig in all the no-load state and the load 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, and each oscillation frequency. Since the signal strength is measured, 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 even with a simple configuration.

Further, the ultrasonic generator generates two types of ultrasonic waves, that is, the burst wave and an ultrasonic wave different from the burst wave, and the signal processing unit measures the propagation time of the different ultrasonic waves. A propagation time measuring unit, 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, and the signal intensity measuring unit for a known axial force. The first master curve for obtaining the propagation time and the second master curve for obtaining the maximum interference frequency at which the signal strength with respect to the known axial force is maximized are provided, and 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 formed on the long member fastened to the different super. A sound wave is incident to measure the propagation time, and the signal intensity measuring unit creates the second master curve 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 accordance with the relative position and the relative posture at the time, and the signal processing unit measures the approximate axis in the propagation time measured from the first master curve. The force was obtained, the interference frequency range in the approximate axial force was obtained from the second master curve, and the maximum interference frequency that became the maximum signal intensity within the interference frequency range was obtained from the measured signal intensity for each oscillation frequency. The axial force of the long member may be measured by the maximum interference frequency and the second master curve.

According to the above configuration, the signal processing unit has a propagation time measuring unit that measures the propagation time of ultrasonic waves different from the burst wave, and a 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 measuring unit that measures the signal strength of an ultrasonic wave different from the burst wave in time, a first master curve that obtains propagation time for a known axial force, and a maximum interference frequency that maximizes the signal strength for a known axial force. It has a second master curve to find. 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 in the approximate axial force F'obtained from the second master curve M2. The frequency range fr is obtained, and the maximum interference frequency Q that is 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 or the like can be misread. It is possible to prevent erroneous measurement. Moreover, 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 under all the load states of the known axial force, and the vertical probe is created at the time of inspection. The signal strength is measured for each oscillation frequency with the child attached to one end of a long member fastened by a vertical probe fixing jig in accordance with the relative position and orientation when the second master curve is created. 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 even with a simple configuration.

Further, the ultrasonic generator generates two types of ultrasonic waves, that is, the burst wave and an ultrasonic wave different from the burst wave, and the signal processing unit measures the propagation time of the different ultrasonic waves. A propagation time measuring unit, 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, and the signal intensity measuring unit for a known axial force. The first master curve for obtaining the propagation time and the second master curve for obtaining the maximum interference frequency at which the signal strength with respect to the known axial force is maximized are provided, and the second master curve is a load of the known axial force. It was obtained by matching the relative position and the relative posture with the vertical probe fixing jig in all the states, and the propagation time measuring unit applies the different ultrasonic waves to the fastened long member. 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, the signal intensity measuring unit measures the propagation time of the incident. The signal strength was measured for each oscillation frequency in a state of being mounted in accordance with the relative position and the relative posture, and the signal processing unit obtained the maximum interference frequency and obtained it from the second master curve. The approximate axial force at the maximum interference frequency is obtained, the propagation time range at the approximate axial force obtained from the first master curve is obtained, and the maximum propagation time that is the maximum signal strength within the propagation time range from the measured propagation time is obtained. , And the axial force of the long member may be measured by the obtained maximum propagation time and the first master curve.

According to the above configuration, the signal processing unit has a propagation time measuring unit that measures the propagation time of ultrasonic waves different from the burst wave, and a 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 measuring unit that measures the signal strength of a burst wave over time, a first master curve that finds the propagation time for a known axial force, and a second master that finds the maximum interference frequency that maximizes the signal strength for a known axial force. It has a curve. Then, 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. The range tr is obtained, and the maximum propagation time T'that has the maximum signal strength 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 ultrasonic waves different from the burst wave can be predicted, and the peak value and the like are misread. It is possible to prevent erroneous measurement due to. Moreover, 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 under all the load states of the known axial force, and the vertical probe is created at the time of inspection. The signal strength is measured for each oscillation frequency with the child attached to one end of a long member fastened by a vertical probe fixing jig in accordance with the relative position and orientation when the second master curve is created. 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 even with a simple configuration.

In such a case, the long member is a bolt, and the vertical probe fixing jig has a fitting portion to be fitted to the bolt head and an accommodating portion for accommodating the vertical probe. The joint portion and the accommodating portion may communicate with each other. Further, the probe orientation indicating portion may be a cable base end portion protruding in the horizontal direction from the vertical probe. Further, the long member is a bolt, and the vertical probe fixing jig has a bottom surface corresponding to the upper surface of the bolt head and an accommodating portion for accommodating the vertical probe, and is provided on the bottom surface. May be provided with a magnet.

Further, in order to achieve the above object, the feature of the axial force measuring method according to the present invention is that an ultrasonic wave is incident from a vertical probe at one end of a long member and a reflected wave reflected from the other end of the long member. In the method of measuring the axial force of the long member based on the signal of the received reflected wave, the ultrasonic wave is a burst wave, and the long member indicates the orientation of the long member. The vertical probe has a long member orientation indicator, and the vertical probe has a vertical probe orientation indicator that indicates the orientation of the vertical probe, and the vertical probe has the vertical probe with respect to the long member. The vertical probe fixing jig is attached to the long member by a vertical probe fixing jig that fixes the relative position of the vertical probe and the relative posture of the vertical probe, and the vertical probe fixing jig is a jig. It has a jig orientation indicating unit for instructing the orientation of the long member, and the burst wave is transmitted / received when creating calibration data of the vertical probe for the long member, or the long member is in a no-load state. The jig orientation indicator and the long member orientation indicator are provided by the vertical probe fixing jig twice, when the burst wave is transmitted and received and when the burst wave is transmitted and received under the load state of the long member. And, by matching the vertical probe orientation indicator, the burst wave is oscillated in a state where the relative position of the vertical probe and the relative posture of the vertical probe with respect to the long member are matched. The signal intensity of the burst wave during the measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave is measured for each oscillation frequency, and the signal intensity for each measured oscillation frequency is used. The purpose is to obtain the maximum interference frequency that has the maximum signal strength within a predetermined interference frequency range, and to measure the axial force of the long member based on the obtained maximum interference frequency.

In such a case, the difference between the no-load maximum interference frequency at which the signal intensity of the long member in the no-load state is maximum and the load maximum interference frequency at which the signal intensity at the known axial force is maximum is obtained in advance. When creating an axial force calculation formula showing the relationship between the frequency and the known axial force, 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. Then, 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 strength is measured for each oscillation frequency, the maximum interference frequency that is the maximum signal strength within a predetermined interference frequency range is obtained from the measured signal strength for each oscillation frequency, and the obtained maximum interference frequency and the axial force are calculated. It is advisable to measure the axial force of the long member by the formula.

Further, the ultrasonic waves are two types of ultrasonic waves, that is, a burst wave and an ultrasonic wave different from the burst wave, and the different ultrasonic waves are previously incident from one end of the long member to propagate the reflected wave. The known axial force is measured by incident the burst wave while changing the oscillation frequency 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. When creating the first master curve for obtaining the propagation time for the long member and the second master curve for obtaining the maximum interference frequency at which the signal strength with respect to the known axial force is maximized, the known axial force of the long member is created. The relative position and the relative posture are matched by the vertical probe fixing jig in all of the load states of the above, and the different ultrasonic waves are incident on the fastened long member to measure the propagation time, and the propagation time is measured. 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 match the relative position and the relative posture at the time of creating the second master curve. The signal strength is measured for each, the approximate axial force at the propagation time measured from the first master curve is obtained, the interference frequency range at the approximate axial force is obtained from the second master curve, and the signal strength for each measured oscillation frequency is obtained. The maximum interference frequency that has the maximum signal strength within the interference frequency range may be obtained from the above, and the axial force of the long member may be measured by the obtained maximum interference frequency and the second master curve.

Further, the ultrasonic waves are two types of ultrasonic waves, that is, a burst wave and an ultrasonic wave different from the burst wave, and the different ultrasonic waves are incident on one end of the long member in advance to propagate the reflected wave. The known axial force is measured by incident the burst wave while changing the oscillation frequency 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. When creating the first master curve for obtaining the propagation time for the long member and the second master curve for obtaining the maximum interference frequency at which the signal strength with respect to the known axial force is maximized, the known axial force of the long member is created. The relative position and the relative posture are matched by the vertical probe fixing jig in all of the load states of the above, and the different ultrasonic waves are incident on the fastened long member to measure the propagation time, and the propagation time is measured. 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 match the relative position and the relative posture at the time of creating the second master curve. The signal strength is measured for each, 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 propagation time range at the approximate axial force obtained from the first master curve is obtained. The maximum propagation time that is the maximum signal strength within the propagation time range may be obtained from the measured propagation time, and the axial force of the long member may be measured by the obtained maximum propagation time and the first master curve.

Further, in order to achieve the above object, the feature of the ultrasonic inspection apparatus according to the present invention is 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. In a configuration including an ultrasonic generator that generates the ultrasonic waves and a signal processing unit that processes the signal of the received reflected wave and inspects the test body, the test body indicates the orientation of the test body. The vertical probe has a vertical probe orientation indicator that indicates the orientation of the vertical probe, and has a relative position of the vertical probe with respect to the test piece and the vertical probe. It has a vertical probe fixing jig that fixes the relative posture of the vertical probe, and the signal processing unit takes the 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 includes a signal intensity measuring unit for measuring the signal intensity of the ultrasonic wave, and has a jig orientation indicating unit for instructing the orientation of the jig, and the vertical probe with respect to the test piece. When the child calibration data is created, the ultrasonic waves are transmitted and received twice, the ultrasonic waves are transmitted and received under no load of the test body, and the ultrasonic waves are transmitted and received under the load state of the test body. By matching the jig orientation indicator, the test piece orientation indicator, and the vertical probe orientation indicator, the relative position and the relative orientation are matched, and the signal processing unit is the signal processing unit. An ultrasonic wave is incident while changing the oscillation frequency, the signal intensity is measured for each oscillation frequency by the signal intensity measuring unit, and the maximum signal within a predetermined interference frequency range from the measured signal intensity for each oscillation frequency. The purpose is to obtain the maximum interference frequency that becomes the intensity and inspect the test piece based on the obtained maximum interference frequency.

Further, in order to achieve the above object, the feature of the ultrasonic inspection method according to the present invention is that ultrasonic waves are incident from the vertical probe at one end of the test body and the reflected wave reflected from the other end of the test body is received. In the method of inspecting the test body based on the signal of the received reflected wave, the test body has a test body orientation indicating unit for instructing the orientation of the test body, and the vertical probe has a vertical probe. It has a vertical probe orientation indicator that indicates the orientation of the tentacle, and this vertical probe is a vertical that fixes the relative position of the vertical probe with respect to the test piece and the relative posture of the vertical probe. It is attached to the test body by a probe fixing jig, and the vertical probe fixing jig has a jig orientation indicating portion for instructing the orientation of the jig, and the vertical probe with respect to the test body. Two times, when the ultrasonic waves are transmitted and received when creating the calibration data of the tentacles, when the ultrasonic waves are transmitted and received under no load of the test piece, and when the ultrasonic waves are transmitted and received under the load state of the test piece. Then, the vertical probe fixing jig makes the jig orientation indicator, the specimen orientation indicator, and the vertical probe orientation indicator coincide with each other so that the vertical probe is relative to the specimen. With the position and the relative posture of the vertical probe matched, the ultrasonic waves are incident while changing the oscillation frequency, and from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency. The signal intensity of the ultrasonic wave at the measurement time of is measured, the maximum interference frequency that is the maximum signal intensity within a predetermined interference frequency range is obtained from the measured signal intensity for each oscillation frequency, and based on the obtained maximum interference frequency. The purpose is to inspect the test piece.

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, the axial force measuring method, and the vertical probe fixing jig according to the present invention, the interference is accurate despite the simple configuration. It has become possible to measure the frequency and more accurately measure the state of the test piece such as axial force.

Other objects, configurations and effects of the present invention will be apparent from the sections of embodiments of the invention below.

It is a block diagram of the axial force measuring apparatus which concerns on this invention. It is a figure explaining the measurement (interferometry) of the interference frequency of a burst wave. It is a figure explaining the relationship between the propagation of ultrasonic waves by the time difference method and the bolt length, (a) is a figure which shows the definition of a bolt and its elongation, (b) is a schematic diagram of a received waveform, and (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 ultrasonic waves by the interferometry and the bolt length, (a) is an example where a half wavelength is a bolt length, (b) is an example where one wavelength is a bolt length, (c). Is an example in which 1.5 wavelengths have a volt length, and (d) is a diagram schematically showing the difference in interference frequencies. It is a schematic diagram explaining the directivity of an ultrasonic wave. It is a schematic diagram explaining the 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 position of the probe in the interferometry. It is a figure which shows the probe fixing jig, (a) is a plan view of the state attached to a bolt head, (b) is a front view of (a), (c) is a plan view of a jig, (d). ) Is a front view of the jig. It is a figure which shows an example of the axial force calculation formula. It is a figure explaining the difference between the load maximum interference frequency and the load maximum interference frequency. It is a figure which shows an example of the measurement data in the state which the probe is fixed. It is a figure which shows an example of the measurement data in the state which attached and detached a probe. It is a figure which shows the probe fixing jig to a bolt by a silicon impression agent. It is a figure explaining the procedure which measured repeatedly by controlling the rotation angle of the probe with respect to a bolt, (a) is a state (0 °) in which the indication part is matched, (b) is a probe from (a). (C) is a state in which the probe is rotated by 180 ° from (a), and (d) is a state in which the probe is rotated by 270 ° from (a). It is a figure which shows an example of the measurement data of FIG. It is a figure corresponding to FIG. 13 in the measurement data of FIG. It is a block diagram of the axial force measuring apparatus which concerns on 2nd Embodiment of this invention. It is a figure explaining the measurement (time difference method) of the propagation time of the second burst wave. It is a flowchart which shows the master curve creation procedure. (A) is a diagram showing an example of the first master curve, and (b) is a diagram showing an example of the second master curve. It is a figure which shows an example of the measurement waveform in the time difference method and the interferometry with a bolt length of 160 mm. It is a flowchart which shows the axial force measurement procedure. An example of a graph in the axial force measurement procedure, (a) is a time waveform, (b) is a first master curve, (c) is a second master curve, (d) is an interference waveform, and (e) is a second master. Each curve is shown. It is a figure which shows an example of the measurement waveform in the time difference method and the interferometry with a bolt length of 30 mm. 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 the third embodiment, (a) is an interference waveform, (b) is a second master curve, (c) is a first master curve, (d) is a time waveform, and (e). ) Indicates the first master curve, respectively. It is a figure which shows the modification example of a probe fixing jig. It is a figure which shows the other modification example of a probe fixing jig. It is a figure which shows the further modification example of a probe fixing jig.

Next, the first embodiment of the present invention will be described in more detail with reference to FIGS. 1 to 17.
As shown in FIG. 1, the axial force measuring device 1 according to the present invention generally receives ultrasonic waves from the head 101 of the bolt 100 as a long member (test body) and at the tip 102 of the bolt 100. A vertical probe 2 (hereinafter abbreviated as "probe") that receives the reflected reflected wave, an ultrasonic generator 30 that generates ultrasonic waves, and a bolt 100 that processes the signal of the received reflected wave. The signal processing unit 3 for measuring the axial force of the above 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 oscillator type probe that also transmits and receives ultrasonic waves is used. Then, the probe 2 is attached to the bolt head 101 by the probe fixing jig 10 described later.

As shown in FIG. 1, the signal processing unit 3 includes an ultrasonic generator 30, and roughly includes a measuring unit 36, a master curve creating unit 37, and an axial force calculating unit 38. The ultrasonic generator 30 generates a burst wave 21 with the probe 2 via the power amplifier 31 according to the setting conditions of the burst wave setting unit 41 described later. The received reflected wave signal (received waveform) is sent to the measuring unit 36 via the protection circuit 32, the frequency filter 33, the A / D converter 34, and the filter 35, and is stored in the data storage unit 39. The measuring unit 36 includes a signal intensity measuring unit 36a for measuring the signal intensity of the burst wave 21 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. The master curve creating unit 37 includes an axial force calculation formula creating unit 37a that creates an axial force calculation formula C showing the relationship of the change amount Δf of the maximum interference frequency Q that maximizes the signal strength with respect to the known axial force (load). .. Then, the axial force calculation unit 38 obtains the axial force from the measured 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 for measuring the interference frequency of the composite wave generated by the ultrasonic waves propagating in the volt 100 interfering with each other (interferometry).

As shown in FIG. 2A, the burst wave 21 becomes the combined waves 20A and 20B due to the interference of the incident ultrasonic waves and the reflected waves propagating in the bolt 100. Further, the burst wave 21 is incident while changing the oscillation frequency within a predetermined range and at a pitch. As shown in the figure, in the burst wave P2A having the oscillation frequency f1, the signal strength of the composite wave 20A immediately after the second reflected echo B2 (the part surrounded by the broken line in the figure) is the first reflected wave 22A and the second reflected wave. It interferes with 23A and becomes weak. On the other hand, in the burst wave P2B having the oscillation frequency f2, the signal strength of the composite wave 20B immediately after the second reflected echo B2 (the part surrounded by the broken line in the figure) interferes with the first reflected wave 22B and the second reflected wave 23B. Become stronger. As described above, if the length of the volt 100 and the length of an integral multiple of the half wavelength of the burst wave 21 of the composite wave match, the interfering waves become in phase and the signal strength increases. In this embodiment, the interference frequency that is the peak of the signal strength is measured for each frequency within a predetermined range and at a pitch, and the interference waveform W as shown in FIG. 2B is generated, and the peak is maximized. Let the interference frequency Q be.

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 less than the propagation time of the second reflected wave (second reflected echo B2). It is good. If it is less than the propagation time of the first reflected wave, no interfering wave is generated and measurement cannot be performed. On the other hand, when the propagation time of the second reflected wave is longer than that, interference occurs in three or more waves (incident wave and first and second reflected waves) propagating in the volt 100, and the signal strength due to the interference can be determined. It will be difficult.

Further, the measurement time (gate) for measuring the maximum interference frequency Q is preferably 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 V to several hundred V, the first reflected echo B1 is several mV to several hundred V, and the second reflected echo B2 is about half that of the first reflected echo B1. Therefore, since the amplitude difference between the transmitted echo and the first reflected echo B1 is too large, the transmitted echo becomes dominant. Therefore, if the time from the propagation time of the first reflected wave to the propagation time of the second reflected wave is set as the measurement time, it becomes difficult to observe the interference. On the other hand, since the ultrasonic wave is attenuated each time the reflection is repeated, the signal strength of the reflected wave after the third time is gradually weakened. 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 set as the measurement time, it becomes difficult to observe the interference because the signal is weak. In this way, by using the interference region between the first reflection echo B1 and the second reflection echo B2, the maximum interference frequency Q can be detected easily and accurately.

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 inputs and sets the oscillation frequency, wave number (length), oscillation frequency pitch, etc. of the burst wave 21. The condition setting unit 42 inputs and sets the length of the bolt 100 and the like. For example, the display unit 43 constantly displays the interference waveform W during the axial force measurement, and also displays the axial force of the measurement result and the like. The axial force calculation formula C is stored in the storage unit 44, and the axial force calculation unit 38 refers to it.

By the way, the length (shaft length) of the bolt 100 as a long member is preferably 5 mm or more and 300 mm or less. For example, as shown in FIG. 3A, if 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 as. 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 for an ultrasonic wave having a propagation velocity of 5.9 mm / μs to reciprocate on the bolt 100 is t = 5 mm × 2 (reciprocating path) ÷ 5.9 mm / μs = 1.6949 ms. On the other hand, the propagation time t'at the bolt 100'is t'= 5.005 mm x 2 (reciprocating path) ÷ 5.9 mm / μs = 1.6966 ms. The difference Δt is Δt = t'−t = 0.0017 μs = 1.7 ns (FIG. 3 (b)). The shorter the bolt length, the shorter this 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. 3D, the low-speed sampling A / D converter has a long sampling cycle, and it is difficult to identify a minute time difference, but the apparatus is inexpensive. That is, the shorter the bolt length, the shorter the sampling cycle is required to detect the time difference Δt. On the other hand, the longer the bolt length, the larger the time difference Δt.

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 an ultrasonic wave having a propagation velocity of 5.9 mm / μs, if a half wavelength has a bolt length as shown in FIG. 4A, the interference wavelength λ = 300 mm × 2 = 600 mm and the interference frequency f in the bolt 100. = 5.9 mm / μs ÷ 600 mm = 9.833 kHz. On the other hand, for 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. Then, as shown in FIG. 6B, when the bolt length becomes one wavelength, the interference wavelength is halved and the interference frequency is doubled. Further, as shown in FIG. 6C, when the bolt length is 1.5 wavelengths, the interference wavelength becomes 1/3 of the half wavelength and the interference frequency becomes 3 times.

Therefore, as shown in FIG. 4D, the peak of the interference intensity appears for each interference frequency. Further, the difference in interference frequencies is 9 Hz. Therefore, the larger the interference order (the number of half wavelengths), the larger the interference frequency and the larger the difference. For example, when an ultrasonic wave having an interference order of about 510 is incident on a 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 (more than 300 mm), the interference wavelength becomes longer and the interference frequency becomes smaller, so that the frequency resolution must be improved and the apparatus becomes expensive. On the other hand, the shorter the bolt length, the larger the difference in interference frequency.

As described above, particularly when the length of the bolt 100 is 5 mm or more and 300 mm or less, the axial force can be achieved with high accuracy by an inexpensive device without using an oscilloscope or an A / D converter having a short sampling cycle or a device having high frequency resolution. Can be measured.

Here, the interferometry will be described in more detail.
The ultrasonic beam B transmitted from the vertical ultrasonic probe has directivity, and the sound pressure (signal intensity) is maximum at the center Ba of the ultrasonic beam B. As shown in FIG. 5, in the ideal probe 200, the center Ba of the beam is perpendicular to the test body N. However, in reality, it seems that the ultrasonic beam B has an inclination G (the inclination of the center Ba with respect to the shortest path V (perpendicular line)) like the probes 201 and 202.

Here, the so-called time difference method (pulse reflection method) detects a change in the propagation time T of the ultrasonic signal (bottom signal) R propagating the test body N. In the ideal probe 200 shown in FIG. 6A, the center Ba of the beam and the shortest path V coincide with each other. On the other hand, in the probes 201 and 202 shown in FIGS. (B) and (c), the center Ba and the shortest path V do not match due to the inclination G of the beam B. However, since the beam B propagates with a spread, the center Ba deviates from the shortest path V and the intensity becomes weak, but the signal R'propagating the shortest path V is always received. Moreover, since the shortest path V and the speed of sound do not change, the propagation time T does not change either. That is, in the time difference method, it is considered that the influence of the inclination of the ultrasonic beam B and the change in the probe position on the inspection accuracy is extremely small.

On the other hand, the so-called interferometry method detects a change in the interference frequency of a synthetic wave generated by interference between ultrasonic waves propagating in the test body N. The ultrasonic waves propagating in the center Ba of the beam having the maximum sound pressure have the greatest effect on the interference. In the ideal probe 200 shown in FIG. 7A, the center Ba of the beam and the shortest path V coincide with each other, and the signal of that path is maximized. On the other hand, in the probe 203 shown in FIG. 6B, the center Ba of the beam and the shortest path V do not match, and the signal of the path of the center Ba having the inclination G becomes the maximum. Therefore, the interference waveforms W1 and W2 do not match.

The received signal (interference waveform) is a combination of ultrasonic waves of each path. In the probe 200 without an inclination G shown in FIG. 8A, the path P1 is the shortest path V and is the center Ba. Therefore, the interference waveform W3 is most affected by the ultrasonic waves of the path P1. On the other hand, in the probe 201 having an inclination G shown in FIG. 3B, 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 waves of the path P2. Further, in the probe 202 located at the N-terminal part of the test body shown in FIG. 3C, the path P1 and the path P2 are the same as those in the figure (b), 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, the inclination G and the position of the beam affect the maximum interference frequency Q, so that the inspection accuracy may decrease. In other words, the inspection accuracy can be improved by suppressing the variation depending on the inclination G and the position of the beam.

Therefore, in the present invention, when the probe 2 is placed on the head 101 of the bolt 100 as a long member, ultrasonic waves are transmitted / received when the calibration data of the probe 2 is created, or the long member. The relative position of the probe 2 with respect to the long member 100 and the position of the probe 2 with respect to the long member 100 are performed twice, when the ultrasonic wave is transmitted and received in the no-load state of 100 and when the ultrasonic wave is transmitted and received in the load state of the long member 100. Match the relative postures. Here, the relative position refers to the position of the probe on the probe mounting surface (for example, the head 101) of the long member 100. Further, 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, the vertical probe fixing jig 10 is used as shown in FIG. The jig 10 has a through hole 12 for accommodating and holding the probe 2 in a substantially cylindrical main body portion 11 and a recess 13 for matching (fitting) with the hexagonal shape of the bolt 101, and the through hole 12 and the recess. 13 communicates. A jig orientation indicating unit M1 indicating the orientation of the jig 10 is provided in the vicinity of the through hole 12 on the surface of the main body 11. The jig orientation indicator M1 is a mark or engraving written on, for example, a pen or the like. On the other hand, the probe orientation indicator M2 having the same configuration is provided on the upper surface of the probe 2, and the specimen orientation indicator M3 having the same configuration is provided on the upper surface of the bolt head 101. There is. By matching these orientation indicating units M1 to M3, the relative position and the relative posture of the probe 2 with respect to the bolt 100 are maintained.

Here, the procedure for measuring the axial force by the interferometry in the present embodiment will be described.
First, the test piece orientation indicator M3 on the surface of the bolt head 101 to be inspected and the jig orientation indicator M1 on the surface of the jig body 11 are aligned, and the recess 13 of the jig 10 and the bolt head 101 are fitted. To install. Further, the jig orientation indicator M1 and the probe orientation indicator M2 are aligned. By matching the orientation indicating units M1 to 3 via the jig 10, the relative position and the relative posture of the probe 2 with respect to the bolt 100 at the time of the 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, the axial force as shown in FIG. Create calculation formula C (calibration curve). When collecting data, the ultrasonic generator 30 generates a burst wave 21 while changing the frequency of the probe 2 according to the conditions set in the burst wave setting unit 41, and receives the reflected signal. The signal strength is collected at the gate (measurement time) set by the signal strength measuring unit 36a, and the relationship between the frequency and the collected signal strength is generated as an interference waveform W, and the maximum interference frequency at which the signal strength is maximized in the interference waveform W is generated. Find Q. Then, as shown in FIG. 11, the axial force calculation formula creating 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. Axial force calculation formula C to be calculated is obtained. As shown in the figure, the axial force (load) and the amount of change Δf have a nearly linear relationship. 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 is measured with the bolt at the time of verification after the above calibration is completed, the bolt 100 used for the calibration is fastened at the measurement point, but before the axial force measurement (or after the axial force measurement), under no load condition. , The probe 2 is attached to the bolt head 101 by the jig 10 so that the orientations of the test piece orientation notation M3, the jig orientation notation M1 and the probe orientation notation M2 match in the same manner as described above. Collect unloaded axial force data.

When fastening the bolts, the jig 10 and the like interfere with the fastening. Therefore, the jig 10 and the like are temporarily removed and fastened using a fastener such as a torque wrench. When the predetermined fastening conditions for measuring the axial force are met, the fastener is removed, and the bolt 100 is searched again by the jig 10 so that the orientations of the orientation indicating portions M1 to 3 match in the same manner as described above. Attach the child 2 and collect axial force data. As a result, the relative position and posture of the probe 2 with respect to the bolt 100 can be determined twice, when the ultrasonic waves are transmitted and received when creating the axial force calculation formula as calibration data, and when the ultrasonic waves are transmitted and received under load. Can be matched. If necessary, the measurement may be performed by repeating the tightening with the fastener. Then, the measured amount of change Δf of the maximum interference frequency is introduced into the previously obtained axial force calculation formula C to calculate the axial force.

Here, even when the axial force is measured with a bolt different from the bolt at the time of verification, the measurement method is the same as described above. Although it is different from the test piece orientation indicator M3 used at the time of verification because the individual bolt is different, the test piece orientation indicator M3 is uniquely determined by the bolt, and the relative positions of the bolt 100, the jig 10, and the probe 2 are relative to each other. And 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 matched between the transmission and reception of ultrasonic waves in the no-load state and the transmission and reception of ultrasonic waves in the load 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 reflection signal strength was maximized was searched for. At that position, the probe 2 was fixed, and the interference frequency peak (maximum interference frequency) was measured in the no-load state and under the predetermined load conditions (measured with no load, 15 kN load, 45 kN load, and 60 kN load). Then, a graph of the difference frequency (change amount Δf) vs. load from 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 when collecting calibration data, no load → 15 kN load → 45 kN load → 60 kN load and load are applied to the bolt 100 each time. The interference frequency peak was acquired (Fig. 12, Legend A1). Further, after returning to the no-load state with the probe 2 fixed, the interference frequency peaks were repeatedly acquired while applying the same load while the probe 2 was fixed (FIGS. 12 Legends A2 and A3).
When the probe 2 is left fixed, the reproducibility of the interference frequency peak is extremely high no matter how many times the measurement is repeated. This indicates that the axial force can be measured accurately 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 search for the probe position where the bottom reflection signal strength is maximized. After that, while the position of the probe 2 remained fixed, a load was applied to the bolt 100 in the order of no load → 15 kN load → 45 kN load → 60 kN load, and an interference frequency peak was acquired each time (Legend A in FIG. 13). In addition, each time after returning to the no-load state, the probe 2 is once attached and detached from the bolt 100, the probe position where the bottom reflection signal strength is maximized is searched, and then interference is applied while applying the same load. Frequency peaks were acquired repeatedly (Fig. 13, Legends B, C, D and E).
As a result, it was confirmed that the straight line of the load-interference frequency peak was shifted by attaching and detaching the probe 2. This means that when measuring the axial force of the bolt 100 to which an unknown load is applied, the measured axial force will vary under the condition that the probe 2 is removed. Further, even in a no-load state, the measured axial force varies by attaching and detaching the probe 2.

(4) Confirmation of the effect of the probe rotation angle on the unloaded bolt Here, a probe fixing jig 10'made of a silicon impression agent as shown in FIG. 14 was manufactured, and the probe position with respect to the bolt 100 was determined. Along with fixing, marks M1 to 3 for clarifying the orientation are described on each of 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. Made it controllable. Under this circumstance, as shown in FIG. 15, the probe 2 is rotated by 90 °, 180 ° and 270 ° from the reference orientation (sensor rotation angle 0 °), and the rotation angle is 0 ° and the interference frequency at each rotation angle. Peak measurement was performed. Further, the probe 2 is once removed from the bolt 100, and the probe 2 is 90 °, 180 ° and 270 ° from the reference orientation based on the marks of the bolt 100, the jig 10'and the probe 2. The routine of rotating and measuring the rotation angle of 0 ° and the interference frequency peak at each rotation angle was repeated three times.
Here, FIG. 16 shows a graph in which the interference frequency peak f in the no-load state measured for each rotation angle is plotted. Since this measurement is performed under no-load conditions, the length of the bolt does not change originally, and ideally the interference frequency peak should not change, but variations d1 to 4 occur at each angle. ing. Within the same angle, the variations d1 to d4 can be suppressed to be relatively small. However, considering the measurement results at all angles, there is a possibility that a variation D may occur between the minimum value at 270 ° and the maximum value at 180 °. That is, it is shown that the rotation angle (azimuth) of the probe 2 changes (does not match in a specific azimuth), so that the output of the axial force varies even when there is no load. By fixing the tentacle position and angle, it is possible to reduce variations in the output of axial force.

(5) Confirmation of the effect of the probe rotation angle on the load bolt With the bolt 100 unloaded, the probe 2 is once attached and detached from the bolt 100, but the probe position and probe 10'are used. The rotation angle was set under the same conditions. After that, the probe 2 was fixed and a load was applied to the bolt 100 in the order of no load → 15 kN load → 45 kN load → 60 kN load, and an interference frequency peak was acquired each time (Fig. 17, Legend A). After returning to the no-load state, the probe 2 is once attached and detached from the bolt 100, but after setting the probe position and rotation angle under the same conditions using the jig 10', the load is also applied in the same manner. The interference frequency peaks were repeatedly acquired while adding the above (Fig. 16, Legends B, C, D and E).
As a result, it was confirmed that the variation of the interference frequency peak was remarkably reduced, unlike FIG. 13 in which the probe 2 was set using only the signal strength as a guideline. This means that when measuring the axial force of a bolt 100 to which an unknown load is applied, the probe position and rotation angle can be made the same even if the probe 2 is attached or detached. This means that the variation in the measured axial force value can be reduced, and the variation in the measured axial force value can be reduced even in the no-load state. In this way, by matching the relative position of the probe with respect to the long member and the relative posture of the probe at the time of calibration or measurement under no load and at the time of measurement under load. Variations in measurement data can be suppressed.

In the experiment, the jig 10'was made with a silicon impression agent, but the above-mentioned jig 10 can also be used. Further, in the above experiment, the position of the probe that maximizes the bottom reflection signal intensity was found, and the position was made unchanged. However, the relative position of the probe 2 may be the same as the position of the probe 2 at the time of the above two transmissions and receptions, and for example, the center of the bolt 100 may be matched as the probe position. ..

In addition, in conventional vertical flaw detection such as inspection of scratches inside the material, the device is adjusted (calibrated) before flaw detection so that the response (reflection signal amplitude) from reflection sources of the same size is the same. Since this is done, the inclination of the ultrasonic beam does not substantially matter. For this reason, in the conventional usage method, "change in the relative posture (beam inclination and rotation angle (azimuth)) of the probe" is not usually a problem, and this "fixing the relative posture" is also possible. 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 interferometry, it is possible to measure the change in the length of the bolt 100 from the interference frequency peak of the ultrasonic wave according to the bolt length, and it can be converted into the axial force. In this measurement, the variation of the measurement data was small in the case of elongated bolts, and the measurement data tended to vary in the case of thick and short bolts. 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, the variation in the measurement data can be reduced even with a thick and short bolt. Further, since there is a considerable possibility that the inclination of the ultrasonic beam peculiar to the probe is caused, the variation in data can be further suppressed by matching the postures of the probes 2.

Next, the second embodiment of the present invention will be described. In the following embodiments, the same members as those in the above embodiments are designated by the same reference numerals.
In the second embodiment, as shown in FIG. 18, the measuring unit 36 includes a signal strength measuring unit 36a and a propagation time measuring unit 36b for measuring the propagation time of the second burst wave 60 different from the previous burst wave 21. .. Further, the master curve creating unit 37 has the maximum signal strength with respect to the known axial force (load) and the first master curve creating unit 37b for creating the first master curve M1 for obtaining the propagation time with respect to the known axial force (load). The second master curve creating unit 37c for creating the second master curve M2 for obtaining the maximum interference frequency is provided. Then, the axial force calculation unit 38 obtains the axial force from the measured values of the measuring 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 previous burst wave 21 and the second burst wave 60 as ultrasonic waves different from the burst wave 21. The second burst wave 60 is used to measure the propagation time of the ultrasonic wave propagating in the volt 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 measured accurately by using the values obtained by these methods. ..

As shown in FIG. 19A, the second burst wave 60 is preferably a wave number whose wave number is 0.5 or more and shorter than the arrival time of the first reflected wave (B1: first reflected echo). When the wave number is less than 0.5, the burst wave (ultrasonic) generation efficiency 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), and it becomes difficult to measure the propagation time. In the present embodiment, the time difference T between the transmission echo 60'(S) and the first reflection echo 61'(B1) of the second burst wave 60 shown in FIG. 19A is obtained as the propagation time T, and FIG. The time waveform W'as shown in b) is generated.

Next, the axial force measurement procedure will be described with reference to FIGS. 20 to 24.
As shown in FIG. 20, before the axial force measurement, the first and second master curves M1 and M2 are created using test bolts having the same configuration as the target bolt. First, the test bolt is set in a tensile tester, a hydraulic jack, or the like, 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 a 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). Then, when the waveform data creation is completed by the propagation time measuring unit 36b (S3), the ultrasonic generator 30 generates the burst wave 21 in the probe 2 according to the conditions set in the burst wave setting unit 41. The reflected signal is received and 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 3 with the above-mentioned jig 10. As a result, variations in measured values are suppressed.

If all the measurements are not completed (S5), the axial force is changed (S7) and the above steps are repeated. When the measurement is completed at each axial force (S5), the first master curve creating unit 37a is shown in FIG. 21 (a) from the propagation time of the second burst wave 60 measured by the propagation time measuring unit 36b and the set axial force. The first master curve M1 such as is created (S6). Further, the second master curve creating unit 37b creates the second master curve M2 as shown in FIG. 21 (b) from the maximum interference frequency of the burst wave 21 measured by the signal strength measuring unit 36a and the set axial force (S6). .. The created first and second master curves M1 and M2 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, the axial force measurement is performed.

Here, for example, as shown in FIG. 22, when the volt 100 is relatively long, it is easy to identify 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, 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 to the condition setting unit 42 as described above. The length of the bolt 100 is input (S10). For example, the oscillation frequency is 5 MHz (for example, the variable range is 5.0 MHz to 5.1 MHz), the wave number of the second burst wave 60 is 1, the wave number of the burst wave 21 is 600, the oscillation frequency interval is 1 kHz, and the length of the volt 100 is 160 mm. 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. 24 (b) (c)). In the present embodiment, the interference frequency range fr is set to about 10 kHz, but this is only an example and is set in an appropriate numerical range.

Then, if the approximate axial force F'and the interference frequency range fr can be calculated (S14), the burst wave 21 is generated and reflected while changing the frequency at the frequency interval set within the oscillation frequency range set by the ultrasonic generator 30. Receive the signal (S15). At this time, the reflected wave is received in a state where the probe 2 is attached by the above-mentioned jig 10 so as to match the relative position and the relative posture of the probe when the second master curve M2 is created. Then, the signal strength measuring unit 36a generates the interference waveform W and obtains the maximum interference frequency Q from the interference frequency range fr previously obtained in the interference waveform W (S16, FIG. 24D). Then, the axial force calculation unit 38 substitutes the obtained maximum interference frequency Q into the second master curve M2 to calculate the axial force F (S17, FIG. 24 (e)). In this way, by predicting the frequency range fr in which the maximum interference frequency Q of the burst wave 21 can appear using the second burst wave 60 in advance, the maximum interference frequency Q can be calculated accurately without misunderstanding. Axial force can be measured with high accuracy by an inexpensive device without using an expensive device having a high frequency resolution as described above. Moreover, since the relative position and relative attitude of the probe at the time of creating the second master curve and at the time of inspection (when calculating the axial force) are matched, the measurement error of the interference frequency due to the mismatch between the relative position and relative attitude of the vertical probe is made. Can be suppressed.

Next, a third embodiment of the present invention will be described.
In the second embodiment, the approximate axial force F'was calculated from the propagation time T of the second burst wave 60, and the interference frequency range fr was obtained from the second master curve M2 based on the approximate axial force F'. However, the burst wave 21 is applied first, 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 volt 100 is relatively short, it is easy to identify 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 to the condition setting unit 42 as described above. Enter the length of the bolt 100 (S20). Next, the ultrasonic generator 30 generates the burst wave 21 and receives the reflected signal (S21). At this time, by using the jig 10 described above, the orientation indicator M1 to 3 are matched, and the probe 2 is attached in accordance with the relative position and posture of the probe when the second master curve M2 is created. Receive in the received state. Then, the signal strength measuring unit 36a generates the interference waveform W and obtains the maximum interference frequency Q (S22, FIG. 27A).

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. Further, the axial force calculation unit 38 obtains the propagation time range tr in the approximate axial force F'from the first master curve M1 (S23, FIGS. 27 (b) (c)).

Then, 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 the time waveform W'and obtains the 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 this is only an example and is set in an appropriate numerical range.

Then, the axial force calculation unit 38 substitutes the obtained maximum propagation time T'into the first master curve M1 to calculate the axial force (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 first using the second burst wave, the maximum propagation time T'is accurately predicted without being mistaken. Since it can be calculated, the axial force can be measured with high accuracy by an inexpensive device without using an A / D converter or the like having a short sampling cycle as described above.

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

Further, each direction indicating unit is not limited to a mark, a marking, or the like. For example, as shown in FIG. 29, a probe 2'in which the cable connecting portion 2a is projected in the horizontal direction is used, and the connecting portion 2a is used. May be used as the probe orientation indicator M2. Similarly, the test body orientation indicating unit M3 can also use the characteristic shape of the test body such as a bolt (for example, the marking of the manufacturer or the start and end points of the screw groove) as the indicating unit. 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 of the housing 2b, thereby aligning the hexagonal corners. In addition, the relative positions can be easily matched with each other, and the magnets prevent misalignment and stabilize the relative posture.

It should be noted 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 into an asymmetric shape and forming a recess 13 that fits into the jig 10. Further, the jig 10 may be provided with slits or holes to facilitate identification of other orientation indicating portions. Further, the test body is not limited to a long member (bolt), and can be applied to, for example, a plate-shaped body.

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 time difference is not limited to this, and may be, for example, a time difference between the first reflection echo 61'(B1) and the second reflection echo 62'(B2). Further, as shown in FIG. 19B, the peak time was measured as the propagation time T. However, the propagation time is not limited to the peak time, and for example, the time obtained by other methods such as zero cross time, threshold cross time, and cross-correlation method can be set as the propagation time. The same applies to the maximum propagation time T'.

In each of the above embodiments, as shown in FIG. 3B, an amplitude value was used as the signal intensity of the composite wave (reflected signal) of the burst wave. However, the signal strength is not limited to the amplitude value, and it is also possible to use the integrated value (area) or energy of the amplitude. As a result, 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 appropriately set and input, and are not limited to the above numerical values. Further, in the second and third embodiments, the signal processing unit 3 is provided with a master curve creating unit 37. However, it is not always necessary to provide the master curve creating unit 37 in the signal processing unit 3, and at least the first and second master curves M1 and M2 created in advance at the time of measuring the axial force may be configured to be referenceable.

In each of the above embodiments, a single-oscillator type probe that also transmits and receives ultrasonic waves is used for the probe 2, but a two-oscillator type probe may also be used. However, since the structure of the two-oscillator type probe tends to cause an inclination G in the ultrasonic beam B, the one-oscillator type probe can suppress the influence on interference.

In the second embodiment, the propagation time T is measured by the second burst wave 60, the interference frequency range fr is obtained via the approximate axial force F', and the interference frequency range fr is within the set oscillation frequency range of the burst wave 21. The maximum interference frequency Q was obtained within. However, for example, after obtaining the interference frequency range fr, it is also possible to set the interference frequency range fr as the oscillation frequency range of the burst wave 21. As a result, the oscillation frequency range of the burst wave 21 can be limited to the range in which the maximum interference frequency Q will appear, so that the measurement time can be shortened and the axial force can be measured efficiently.

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

The present invention can be used, for example, as an axial force measuring device and a measuring method for fasteners made of bolts, screws, etc. as long members used in automobile parts, mechanical devices, other industrial devices, equipment, plants, and the like. .. It can also be used as an axial force measuring device and a 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. Since the interferometry detects a minute change in the propagation time of ultrasonic waves as a change in the interference frequency, the state of the material associated with the propagation time can be measured. For example, strain measurement, sound velocity measurement, temperature measurement, material measurement, residual stress measurement, etc. of a test piece are possible. Further, it is not limited to the long member (bolt 100), and can be applied to, for example, the wall thickness measurement of a plate material.

1: Axial force measuring device, 2, 2', 2 ": probe, 2a: cable connection part, 2b: housing, 2c: bottom surface (magnet), 2d: oscillator, 3: signal processing part (device body) 4: Display / input / output unit (PC), 10, 10'10A, 10B: Detector fixing jig, 11: Main body, 12: Through hole, 13: Recess, 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: measuring unit, 36a: signal strength measuring unit, 36b: propagation time measuring unit, 37: master curve creating unit, 37a: axial force calculation formula creating unit, 37b: 1st master curve creation unit, 37c: 2nd 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 Part, 60: Second burst wave (different ultrasonic wave), 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: Axis Force calculation formula, F: Axial force, F': Approximate axial force, fr: Interference frequency range, G: Tilt, M1: Jig orientation indicator, M2: Detector orientation indicator, M3: Specimen orientation indicator , N: Specimen, P1 to 3: Path, Q: Maximum interference frequency, R, R': Reflected signal, T: Propagation time, T': Maximum propagation time, tr: Propagation time range, V: Shortest path (vertical line) ), W: Interference waveform, W': Time waveform,

Claims (14)

A vertical 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, an ultrasonic generator that generates the ultrasonic waves, and the received reflected waves. An axial force measuring device including a signal processing unit that processes a signal and measures the axial force of the long member.
The long member has a long member orientation indicating portion that indicates the orientation of the long member.
The vertical probe has a vertical probe azimuth indicator that indicates the orientation of the vertical probe.
It has 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, and the ultrasonic generator generates a burst wave.
The signal processing unit includes 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.
The vertical probe fixing jig has a jig orientation indicating unit for instructing the orientation of the jig, and when transmitting and receiving the burst wave when creating calibration data of the vertical probe for the long member. Alternatively, the jig orientation indicator and the long member orientation can be transmitted and received twice, when the burst wave is transmitted and received in the no-load state of the long member and when the burst wave is transmitted and received in the load state of the long member. By matching the indicator and the vertical probe azimuth indicator, the relative position and the relative posture are matched.
The signal processing unit incidents the burst wave while changing the oscillation frequency, and the signal intensity measuring unit measures the signal intensity for each oscillation frequency.
From the measured signal strength for each oscillation frequency, find the maximum interference frequency that is the maximum signal strength within the specified interference frequency range.
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 has a no-load maximum interference frequency at which the signal intensity of the long member in the no-load state is maximum and a load maximum interference frequency at which the signal intensity at the known axial force is maximum. Further having an axial force calculation formula showing the 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 no-load state and the load state.
The signal strength measuring unit coincides with the relative position and the relative posture at the time of creating the axial force calculation formula at one end of the long member in which the vertical probe is fastened by the vertical probe fixing jig. The signal strength is measured for each oscillation frequency in the mounted state.
The signal processing unit obtains the maximum interference frequency that is the maximum signal intensity within a predetermined interference frequency range from the measured signal intensity for each oscillation frequency.
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 axial force calculation formula. The ultrasonic generator generates two types of ultrasonic waves, the burst wave and an ultrasonic wave different from the burst wave.
The signal processing unit includes a propagation time measuring unit that measures the propagation time of the different ultrasonic waves, and a propagation time measuring unit.
A signal intensity measuring unit that measures the signal intensity of the burst wave during the measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency.
The first master curve for obtaining the propagation time for a known axial force, and
It is provided with a second master curve for finding the maximum interference frequency at which the signal strength 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 the load states of the known axial force.
The propagation time measuring unit measures the propagation time by injecting the different ultrasonic waves into the fastened long member.
The signal strength measuring unit coincides with the relative position and the relative posture at the time of creating the second master curve at one end of the 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 the mounted state.
The signal processing unit obtains an approximate axial force at the propagation time measured from the first master curve.
The interference frequency range in the approximate axial force is obtained from the second master curve.
From the measured signal strength for each oscillation frequency, the maximum interference frequency that is the maximum signal strength within the interference frequency range is obtained.
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, the burst wave and an ultrasonic wave different from the burst wave.
The signal processing unit includes a propagation time measuring unit that measures the propagation time of the different ultrasonic waves, and a propagation time measuring unit.
A signal intensity measuring unit that measures the signal intensity of the burst wave during the measurement time from the propagation time of the reflected wave to the propagation time of the next reflected wave for each oscillation frequency.
The first master curve for obtaining the propagation time for a known axial force, and
It is provided with a second master curve for finding the maximum interference frequency at which the signal strength with respect to the known axial force is maximized.
The second master curve is obtained by matching the relative position and the relative posture with 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 injecting the different ultrasonic waves into the fastened long member.
The signal strength measuring unit coincides with the relative position and the relative posture at the time of creating the second master curve at one end of the long member to which the vertical probe is fastened by the vertical probe fixing jig. The signal strength was measured for each oscillation frequency in the attached state.
The signal processing unit obtains the maximum interference frequency and obtains the maximum interference frequency.
Obtain the approximate axial force at the maximum interference frequency obtained from the second master curve.
The propagation time range at the approximate axial force obtained from the first master curve was obtained.
From the measured propagation time, find the maximum propagation time that gives 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 by the obtained maximum propagation time and the first master curve. The long member is a bolt, and the vertical probe fixing jig has a fitting portion to be fitted to the bolt head and an accommodating portion for accommodating the vertical probe, and the fitting portion and the fitting portion. The axial force measuring device according to any one of claims 1 to 4, wherein the accommodating portion communicates with the accommodating portion. The axial force measuring device according to any one of claims 1 to 5, wherein the vertical probe azimuth indicator is a cable base end portion that projects horizontally from the vertical probe. The long member is a bolt, and the vertical probe fixing jig has a bottom surface corresponding to the upper surface of the bolt head and an accommodating portion for accommodating the vertical probe, and a magnet is provided on the bottom surface. The axial force measuring apparatus according to any one of claims 1 to 4. Ultrasonic waves are incident from the vertical probe at one end of the long member, and the reflected wave reflected from the other end of the long member is received, and the axial force of the long member is applied based on the received reflected wave signal. Axial force measurement method to measure
The ultrasonic wave is a burst wave and is
The long member has a long member orientation indicating portion that indicates the orientation of the long member.
The vertical probe has a vertical probe azimuth indicator that indicates the orientation of the vertical probe.
The vertical probe is attached to the long member by a vertical probe fixing jig that fixes the relative position of the vertical probe and the relative posture of the vertical probe with respect to the long member. ,
The vertical probe fixing jig has a jig orientation indicating unit for instructing the orientation of the jig.
When the burst wave is transmitted / received when the calibration data of the vertical probe for the long member is created, or when the burst wave is transmitted / received in the no-load state of the long member, and the load state of the long member. The vertical probe fixing jig is used to match the jig orientation indicator, the long member orientation indicator, and the vertical probe orientation indicator twice during transmission and reception of the burst wave in the above. In a state where the relative position of the vertical probe and the relative posture of the vertical probe with respect to the long member are matched, the burst wave is incident while changing the oscillation frequency, and the reflection is performed for each oscillation frequency. The signal strength of the burst wave in the measurement time from the wave propagation time to the propagation time of the next reflected wave is measured.
From the measured signal strength for each oscillation frequency, find the maximum interference frequency that is the maximum signal strength within the specified interference frequency range.
An axial force measuring method for measuring the axial force of the long member based on the obtained maximum interference frequency. In advance, the difference between the no-load maximum interference frequency at which the signal strength of the long member in the no-load state is maximum and the load maximum interference frequency at which the signal strength at the known axial force is maximum in the no-load state and the known are known. When creating an axial force calculation formula showing the relationship with the axial force of, 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 where 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. Intensity is measured for each oscillation frequency and
From the measured signal strength for each oscillation frequency, find the maximum interference frequency that is the maximum signal strength within the specified interference frequency range.
The axial force measuring method according to claim 8, wherein the axial force of the long member is measured by the obtained maximum interference frequency and the axial force calculation formula. The ultrasonic waves are two types of ultrasonic waves, the burst wave and an ultrasonic wave different from 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 next reflected wave is obtained from the propagation time of the reflected wave. The first master curve that measures the signal strength of the burst wave in the measurement time up to the propagation time to obtain the propagation time with respect to the known axial force, and the maximum interference frequency at which the signal strength with respect to the known axial force is maximized. When creating the second master curve for obtaining the above, the relative position and the relative posture are matched by the vertical probe fixing jig in all the load states of the known axial force of the long member.
The different ultrasonic waves are incident on 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. The signal strength was measured for each oscillation frequency in a state where the master curve was attached so as to match the relative position and the relative posture at the time of creation.
Obtain the approximate axial force at the propagation time measured from the first master curve.
The interference frequency range in the approximate axial force is obtained from the second master curve.
From the measured signal strength for each oscillation frequency, the maximum interference frequency that is the maximum signal strength within the interference frequency range is obtained.
The axial force measuring method according to claim 8, wherein the axial force of the long member is measured by the obtained maximum interference frequency and the second master curve. The ultrasonic waves are two types of ultrasonic waves, the burst wave and an ultrasonic wave different from 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 next reflected wave is obtained from the propagation time of the reflected wave. The first master curve that measures the signal strength of the burst wave in the measurement time up to the propagation time to obtain the propagation time with respect to the known axial force, and the maximum interference frequency at which the signal strength with respect to the known axial force is maximized. When creating the second master curve for obtaining the above, the relative position and the relative posture are matched by the vertical probe fixing jig in all the load states of the known axial force of the long member.
The different ultrasonic waves are incident on 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. The signal strength was measured for each oscillation frequency in a state where the master curve was attached so as to match the relative position and the relative posture at the time of creation.
Find the maximum interference frequency
Obtain the approximate axial force at the maximum interference frequency obtained from the second master curve.
The propagation time range at the approximate axial force obtained from the first master curve was obtained.
From the measured propagation time, find the maximum propagation time that gives the maximum signal strength within the propagation time range.
The axial force measuring method according to claim 8, wherein the axial force of the long member is measured by 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 including a signal processing unit for processing and inspecting the test piece.
The test body has a test body orientation indicating unit for instructing the orientation of the test body.
The vertical probe has a vertical probe azimuth indicator that indicates the orientation of the vertical probe.
It has 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 piece.
The signal processing unit includes a signal intensity measuring unit that measures 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.
The vertical probe fixing jig has a jig orientation indicating unit for instructing the orientation of the jig, and is used during transmission / reception of the ultrasonic waves when creating calibration data of the vertical probe with respect to the test piece. The jig orientation indicator, the specimen orientation indicator, and the test specimen orientation indicator and the test specimen orientation indicator are performed twice, when the ultrasonic waves are transmitted and received under no load of the test piece and when the ultrasonic waves are transmitted and received under the load state of the test piece. By matching the vertical probe azimuth indicator, the relative position and the relative posture are matched.
The signal processing unit incidents the ultrasonic waves while changing the oscillation frequency, and the signal intensity measuring unit measures the signal intensity for each oscillation frequency.
From the measured signal strength for each oscillation frequency, find the maximum interference frequency that is the maximum signal strength within the specified interference frequency range.
An ultrasonic inspection device that inspects the test piece based on the obtained maximum interference frequency. An ultrasonic inspection method in which an ultrasonic wave is incident from a vertical probe at one end of a test piece, a reflected wave reflected from the other end of the test piece is received, and the test piece is inspected based on the received reflected wave signal. And
The test body has a test body orientation indicating unit for instructing the orientation of the test body.
The vertical probe has a vertical probe azimuth indicator that indicates the orientation of the vertical probe.
This vertical probe is attached to the test body by a vertical probe fixing jig that fixes the relative position of the vertical probe and the relative posture of the vertical probe with respect to the test body.
The vertical probe fixing jig has a jig orientation indicating unit for instructing the orientation of the jig.
When transmitting and receiving the ultrasonic waves when creating calibration data of the vertical probe with respect to the test body, or when transmitting and receiving the ultrasonic waves in a no-load state of the test body, and when the test body is in a loaded state, the ultrasonic waves The vertical probe fixing jig is used to match the jig orientation indicator, the test piece orientation indicator, and the vertical probe orientation indicator with the vertical probe orientation indicator twice during transmission and reception of ultrasonic waves. With the relative position of the vertical probe and the relative orientation of the vertical probe matched, the ultrasonic waves are incident while changing the oscillation frequency, and the propagation time of the reflected wave is followed for each oscillation frequency. The signal intensity of the ultrasonic wave at the measurement time up to the propagation time of the reflected wave of
From the measured signal strength for each oscillation frequency, find the maximum interference frequency that is the maximum signal strength within the specified interference frequency range.
An ultrasonic inspection method for inspecting the test piece based on the obtained maximum interference frequency. A vertical probe fixing jig used in the ultrasonic inspection method according to claim 13.