JP2004077460A - Residual stress distribution measurement device and residual stress distribution measurement method - Google Patents

Residual stress distribution measurement device and residual stress distribution measurement method Download PDF

Info

Publication number
JP2004077460A
JP2004077460A JP2003005518A JP2003005518A JP2004077460A JP 2004077460 A JP2004077460 A JP 2004077460A JP 2003005518 A JP2003005518 A JP 2003005518A JP 2003005518 A JP2003005518 A JP 2003005518A JP 2004077460 A JP2004077460 A JP 2004077460A
Authority
JP
Japan
Prior art keywords
ultrasonic wave
ultrasonic
layer
position
residual stress
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP2003005518A
Other languages
Japanese (ja)
Other versions
JP4031711B2 (en
Inventor
Yasuaki Nagata
永田 泰昭
Original Assignee
Nippon Steel Corp
新日本製鐵株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to JP2002175272 priority Critical
Application filed by Nippon Steel Corp, 新日本製鐵株式会社 filed Critical Nippon Steel Corp
Priority to JP2003005518A priority patent/JP4031711B2/en
Publication of JP2004077460A publication Critical patent/JP2004077460A/en
Application granted granted Critical
Publication of JP4031711B2 publication Critical patent/JP4031711B2/en
Application status is Active legal-status Critical
Anticipated expiration legal-status Critical

Links

Images

Abstract

<P>PROBLEM TO BE SOLVED: To provide a residual stress distribution measurement device and a residual stress distribution measurement method that can directly measure residual stress distribution in an object to be measured. <P>SOLUTION: Beam acquisition parts 40a and 40b direct laser beams L3 to positions where ultrasonic waves of a longitudinal wave, a rolling-direction-displaced transverse wave and a width-direction-displaced transverse wave generated by ultrasonic wave generation parts 20a and 20b return to the surface of an object 2, and acquires reflected laser beams L3. According to waveform data indicating frequency variations in the laser beams L3 detected by interferometers 50a and 50b, a computer 70 computes a propagation time of each ultrasonic wave generated in each progress direction, and computes a horizontal distance between the generation position and detection position of each ultrasonic wave. After the sonic speed of each ultrasonic wave in each layer of the object 2 divided in a thickness direction is computed according to the propagation time and the horizontal distance, according to the longitudinal wave sonic speed in each layer, an internal temperature of each layer is obtained, and according to the sonic speed of each ultrasonic wave and the internal temperature, a residual stress in each layer is computed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a residual stress distribution measuring device and a residual stress distribution measuring method for measuring, for example, a residual stress distribution of a steel material.
[0002]
[Prior art]
In general, in a hot thick plate manufacturing process, a thick plate having desired specification characteristics is manufactured by controlling a rolling condition and a cooling condition of controlled rolling. Information that can be helpful in controlling such rolling and cooling conditions includes temperature information and residual stress information of the thick plate.
[0003]
Conventionally, regarding temperature information, the surface temperature of a thick plate is measured using a radiation thermometer or the like, and a model calculation such as a simulation is performed to estimate the internal temperature of the thick plate. On the other hand, regarding the residual stress information, the residual stress was measured only on the surface of the object to be measured using a contact ultrasonic probe or the like, or only the average value of the residual stress was measured in the thickness direction of the test piece ( For example, see Non-Patent Document 1.) Further, there is no technology for directly measuring the residual stress distribution of a steel material online, and only a technology for estimating and obtaining the residual stress distribution has been proposed (for example, see Patent Document 1).
[0004]
[Non-patent document 1]
"Sound elasticity", published by the Non-Destructive Inspection Association, 1994, p. 94-107
[Patent Document 1]
JP-A-2000-301220
[0005]
[Problems to be solved by the invention]
As described above, conventionally, it has not been possible to directly measure the residual stress distribution of the measurement object. Conventionally, in the hot thick plate manufacturing process, rolling control in consideration of residual stress information is not actually performed. However, in the thick plate manufacturing process, there is a problem that the steel material warps due to the influence of the residual stress. For this reason, if information on the residual stress is obtained online hot, it is possible to perform better rolling control, such as performing control for reducing the residual stress.
[0006]
The present invention has been made based on the above circumstances, and an object of the present invention is to provide a residual stress distribution measuring device and a residual stress distribution measuring method capable of directly measuring a residual stress distribution of an object to be measured. .
[0007]
The present invention has been made based on the above circumstances, and an object of the present invention is to provide a residual stress distribution measuring device and a residual stress distribution measuring method capable of measuring a residual stress distribution of a measurement object hot online. Things.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 divides a plate-shaped object to be measured into a plurality of layers along a thickness direction thereof, and forms each of the layers at a predetermined position on the surface of the object to be measured. A residual stress distribution measuring device for measuring a residual stress of the object, irradiating a first laser beam and a second laser beam having different frequencies to the same position (ultrasonic generation position) of the measurement object at a predetermined incident angle. By doing so, causing interference between the first laser beam and the second laser beam, inside the measurement object, while generating ultrasonic waves that travel obliquely to the surface of the measurement object, Ultrasonic wave generating means configured to be movable along a plane parallel to the surface of the measuring object, longitudinal ultrasonic waves generated by the ultrasonic wave generating means, transverse waves displaced in the longitudinal width direction of the measuring object Ultrasonic, the measurement For each of the transverse ultrasonic waves displaced in the lateral width direction of the object, a third laser beam is applied to a position (ultrasonic detection position) where the ultrasonic waves are reflected on the bottom surface of the measurement object and returned to the surface again. Guiding, acquiring the third laser beam reflected on the surface of the measurement object, and a beam acquisition unit configured to be movable along a plane parallel to the surface of the measurement object, and the ultrasonic wave generation unit Distance calculating means for obtaining a distance between the ultrasonic wave generating position and the ultrasonic detecting position for the ultrasonic wave based on the positional information of the ultrasonic wave and the position information of the beam obtaining means. Frequency change detecting means for detecting a change in the frequency of the third laser beam caused by the vibration of the ultrasonic wave, based on the third laser beam, and a frequency change detected by the frequency change detecting means. Calculating means for calculating a propagation time during which the ultrasonic wave has propagated inside the object to be measured based on waveform data representing a frequency change of the third laser beam. The direction is set in advance by the same number as the number of the layers, and the distance calculating means sets the ultrasonic wave for each ultrasonic wave each time the ultrasonic wave generating means generates the ultrasonic wave in each traveling direction. Finding the distance between the generation position and the ultrasonic detection position, the calculating means, for each of the ultrasonic waves, in the traveling direction each time the ultrasonic generating means generates the ultrasonic waves in each of the traveling directions. The propagation time of the generated ultrasonic wave is obtained, and the propagation time of the ultrasonic wave generated in each of the traveling directions and the ultrasonic generation position of the ultrasonic wave generated in each of the traveling directions obtained by the distance calculating means. Calculating the sound velocity of the ultrasonic wave in each layer based on the distance between the position and the ultrasonic detection position, and the internal temperature of each layer based on the calculated sound velocity of the one ultrasonic wave in each layer. And calculating the residual stress of each layer based on the sound speed of each ultrasonic wave in each layer and the internal temperature of each layer.
[0009]
According to a second aspect of the present invention, in the residual stress distribution measuring apparatus according to the first aspect, the first laser beam and the second laser beam are two laser beams generated from one laser device. It is characterized by being obtained by branching and making one of the branched laser beams incident on the acousto-optic element.
[0010]
According to a third aspect of the present invention, in the residual stress distribution measuring device according to the first or second aspect, the ultrasonic wave generating means sets an incident angle of at least one of the first laser beam and the second laser beam. The adjustment is performed to control the traveling direction of each ultrasonic wave when it is generated.
[0011]
According to a fourth aspect of the present invention, in the residual stress distribution measuring device according to the first, second or third aspect, two sets of the ultrasonic wave generating means, the beam obtaining means and the frequency detecting means are provided. It is.
[0012]
The invention according to claim 5 for achieving the above object is to divide a plate-shaped object to be measured into a plurality of layers along a thickness direction thereof, and to form each of the layers at a predetermined position on the surface of the object to be measured. A residual stress distribution measuring method for measuring the residual stress of the object, irradiating a first laser beam and a second laser beam having different frequencies to the same position (ultrasonic generation position) of the measurement object at a predetermined incident angle, respectively. Thereby causing interference between the first laser beam and the second laser beam, and generating an ultrasonic wave that travels obliquely with respect to the surface of the measurement target inside the measurement target. Guiding the third laser beam to a position (ultrasonic detection position) where the ultrasonic wave is reflected on the bottom surface of the measurement object and returns to the surface again, and the second laser beam reflected on the surface of the measurement object. Three laser bees A third step of obtaining the distance between the ultrasonic wave generation position and the ultrasonic detection position for the ultrasonic wave, and based on the third laser beam obtained in the second step. A fourth step of detecting a change in the frequency of the third laser beam caused by the vibration of the ultrasonic wave, and waveform data representing the frequency change of the third laser beam detected in the fourth step. A fifth step of calculating the propagation time during which the ultrasonic wave propagated inside the measurement object based on the ultrasonic wave of the longitudinal wave generated in the first step, and the transverse wave displaced in the longitudinal width direction of the measurement object. For each of the ultrasonic waves and the ultrasonic waves of the transverse wave displaced in the lateral width direction of the measurement object, the traveling direction at the time of generation is set in advance by the same number as the number of the layers, and each of the set each is set. By sequentially generating the ultrasonic waves in the row direction and repeating the first step to the fifth step, for each ultrasonic wave, the ultrasonic wave generation position for the ultrasonic waves generated in each traveling direction A sixth step of determining a distance between the ultrasonic wave and the ultrasonic detection position and a propagation time of the ultrasonic wave generated in each of the traveling directions; and, for each ultrasonic wave, the propagation of the ultrasonic wave generated in each of the traveling directions. Based on time and the distance between the ultrasonic generation position and the ultrasonic detection position for the ultrasonic waves generated in each traveling direction, a seventh step of calculating the sound speed of the ultrasonic waves in each layer, An eighth step of obtaining an internal temperature of each of the layers based on the sound speed of the one ultrasonic wave in each of the layers calculated in the seventh step; and a sound of each of the ultrasonic waves in each of the layers. A ninth step of calculating the residual stress of each of the layers based on the speed and the internal temperature of each of the layers.
[0013]
According to a sixth aspect of the present invention, in the method for measuring a residual stress distribution according to the fifth aspect, the first laser beam and the second laser beam are two laser beams generated by one laser device. It is characterized by being obtained by branching and making one of the branched laser beams incident on the acousto-optic element.
[0014]
According to a seventh aspect of the present invention, in the residual stress distribution measuring method according to the fifth or sixth aspect, in the first step, an incident angle of at least one of the first laser beam and the second laser beam is adjusted. Thus, the traveling direction of each ultrasonic wave when it is generated is controlled.
[0015]
In order to achieve the above object, the invention according to claim 8 divides a plate-shaped measurement target into a plurality of layers along a thickness direction thereof, and sets each of the layers at a predetermined position on the surface of the measurement target. A residual stress distribution measuring device for measuring the residual stress of the object to be measured, wherein at a predetermined position (ultrasonic generation position) on the surface of the object to be measured, the device is inclined inside the object to be measured, Ultrasonic wave generating means configured to generate an ultrasonic wave that travels along, and configured to be movable along a plane parallel to the surface of the measurement object, and a longitudinal ultrasonic wave generated by the ultrasonic wave generating means, For each of the transverse ultrasonic waves displaced in the longitudinal direction of the measuring object and the transverse ultrasonic waves displaced in the lateral direction of the measuring object, the ultrasonic waves are reflected on the bottom surface of the measuring object and again on the surface. Return position (ultrasonic detection position) Ultrasonic detection means configured to detect the ultrasonic waves and move along a plane parallel to the surface of the measurement object, position information of the ultrasonic generation means, and position information of the ultrasonic detection means Based on the ultrasonic wave, the distance calculation means for obtaining the distance between the ultrasonic wave generation position and the ultrasonic detection position, based on the ultrasonic waveform data obtained by the ultrasonic detection means Calculating means for calculating the propagation time during which the ultrasonic wave propagated inside the measurement object, and the traveling direction at the time of generation of each ultrasonic wave is set in advance by the same number as the number of the layers, The distance calculating means, for each of the ultrasonic waves, each time the ultrasonic wave generating means to generate the ultrasonic waves in each of the traveling directions, to determine the distance between the ultrasonic generation position and the ultrasonic detection position, The arithmetic means is For each ultrasonic wave, each time the ultrasonic wave generating means generates the ultrasonic wave in each of the traveling directions, the propagation time of the ultrasonic wave generated in the traveling direction is obtained, and the ultrasonic waves generated in each of the traveling directions. Of the ultrasonic wave in each layer based on the distance between the ultrasonic wave generation position and the ultrasonic wave detection position for the ultrasonic wave generated in each traveling direction obtained by the propagation time and the distance calculation means. Calculate the sound speed, and determine the internal temperature of each layer based on the calculated sound speed of the one ultrasonic wave in each layer, and calculate the sound speed of each ultrasonic wave in each layer and the internal temperature of each layer. It is characterized in that the residual stress of each layer is calculated.
[0016]
According to a ninth aspect of the present invention, in the residual stress distribution measuring device according to the eighth aspect, a probe is used as each of the ultrasonic wave generating means and the ultrasonic wave detecting means.
[0017]
The invention according to claim 10 for achieving the above object is to divide a plate-shaped object to be measured into a plurality of layers along a thickness direction thereof, and to form each of the layers at a predetermined position on the surface of the object to be measured. A residual stress distribution measuring method for measuring the residual stress of the object to be measured, wherein at a predetermined position (ultrasonic generation position) on the surface of the object to be measured, the surface of the object to be measured is oblique A first step of generating an ultrasonic wave that travels to the target, and a second step of detecting the ultrasonic wave at a position (ultrasonic detection position) where the ultrasonic wave is reflected on the bottom surface of the measurement object and returns to the surface again. And a third step of obtaining a distance between the ultrasonic wave generation position and the ultrasonic detection position for the ultrasonic wave, based on waveform data of the ultrasonic wave obtained by detecting the ultrasonic wave in the second step. Before the ultrasound A fourth step of determining a propagation time propagated inside the measurement object, a longitudinal ultrasonic wave generated in the first step, a transverse ultrasonic wave displaced in a longitudinal width direction of the measurement object, the measurement object For each of the transverse ultrasonic waves displaced in the width direction, the traveling direction at the time of generation is set in advance by the same number as the number of the layers, and the ultrasonic waves are sequentially generated in the set traveling directions. Then, by repeating the first step to the fourth step, for each ultrasonic wave, between the ultrasonic generation position and the ultrasonic detection position for the ultrasonic wave generated in each traveling direction A fifth step of calculating the distance of the ultrasonic wave and the propagation time of the ultrasonic wave generated in each of the traveling directions; and for each ultrasonic wave, the propagation time of the ultrasonic wave generated in each of the traveling directions and each of the traveling directions. A sixth step of calculating a sound velocity of the ultrasonic wave in each of the layers based on a distance between the ultrasonic wave generation position and the ultrasonic detection position for the ultrasonic wave generated in the sixth step; A seventh step of obtaining the internal temperature of each layer based on the sound velocity of the one ultrasonic wave in each of the layers, and the residual stress of each layer based on the sound velocity of each ultrasonic wave and the internal temperature of each layer in each layer. And an eighth step of calculating.
[0018]
According to an eleventh aspect of the present invention, in the method for measuring a residual stress distribution according to the tenth aspect, in the first step, an ultrasonic wave is generated using a probe, and in the second step, an ultrasonic wave is generated using a probe. It is characterized by detecting sound waves.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a residual stress distribution measuring device according to an embodiment of the present invention, and FIG. 2 is a graph showing a relationship between an internal temperature and a longitudinal wave velocity for a certain steel material.
[0020]
The residual stress distribution measuring device according to the present embodiment measures a residual stress distribution inside a measurement object in a non-contact manner. Here, as an object to be measured, for example, a plate-like steel material (thick plate) manufactured by a hot process in an ironworks is assumed. The surface temperature of such a thick plate is usually around 700 ° C. In particular, in the present embodiment, the thick plate is divided into a plurality of layers along the thickness direction, and the residual stress of each layer is calculated at a predetermined measurement position to obtain the internal residual stress distribution of the thick plate. I will.
[0021]
The residual stress can be obtained from the following equation using the sound speed ratio method. That is, the sound velocity ratio is R, and the stress in the rolling direction (longitudinal width direction) of the thick plate is σ.1, The stress in the width direction (width direction) of the thick plate2Then
R≡2VL/ (VS1-VS2)
= R0+ CR・ (Σ1+ Σ2) + F · (TT0)
It is. Where VLIs the speed of sound of longitudinal ultrasonic wave, VS1Is the sound velocity of the transverse ultrasonic wave displaced in the rolling direction of the thick plate, VS2Is the sound velocity of the transverse ultrasonic wave displaced in the width direction of the thick plate. Also, R0At no stress and at room temperature T0Sound speed ratio at the time, CRIs a sound elastic constant. Sound speed ratio R0, Sound elastic constant CR, And the parameter F at the time of no stress are measured in advance with a sample (steel specimen). Therefore, the sound velocity V propagating through each layer of the thick plateL, VS1, VS2And the internal temperature T of each layer, the residual stress σ in each layer is obtained by substituting them into the above equation.1+ Σ2Can be calculated.
[0022]
By the way, as is well known, in various types of steel materials, there is a close relationship between the internal temperature and the speed of sound of longitudinal waves propagating through the inside. 3 shows an example of the relationship between the internal temperature and the sound speed of longitudinal waves for the steel material shown in FIG. 2. In FIG. 2, the horizontal axis represents the internal temperature of the steel material, and the vertical axis represents the speed of sound of the longitudinal wave. From this graph, it can be seen that the lower the sound speed of the longitudinal wave, the higher the internal temperature of the steel material tends to be. In the residual stress distribution measuring device of the present embodiment, after determining the velocity of the longitudinal wave in each layer of the thick plate, the internal temperature of the thick plate is determined by using the relationship between the internal temperature and the longitudinal wave velocity as shown in FIG. I will ask for. At this time, the sound speed of the longitudinal wave in each layer of the thick plate is calculated using the laser ultrasonic method.
[0023]
As shown in FIG. 1, the residual stress distribution measuring device of the present embodiment includes an ultrasonic generation laser 10, a first ultrasonic generation unit 20 a and a second ultrasonic generation unit 20 b, and an ultrasonic detection laser 30. A first beam acquisition unit 40a and a second beam acquisition unit 40b, a first Fabry-Perot interferometer 50a and a second Fabry-Perot interferometer 50b, a first photodetector 60a and a second photodetector 60b, And a computer 70. The residual stress distribution measuring device is provided with beam splitters 81 and 82, a mirror 84, condenser lenses 86, 87, 88 and 89, optical fibers 91, 92, 93 and 94 as optical components. .
[0024]
The laser 10 for generating ultrasonic waves is a laser for exciting ultrasonic waves in the object 2 to be measured. As the ultrasonic wave generating laser 10, for example, a YAG laser or CO2Use a high energy pulsed laser such as a laser. Hereinafter, the frequency of the laser beam emitted from the ultrasonic wave generation laser 10 is f1And its wavelength as λ1And
[0025]
The laser beam emitted from the ultrasonic wave generation laser 10 is split by the beam splitter 81 into two laser beams. One of the split laser beams enters the first ultrasonic generator 20a, and the other laser beam enters the second ultrasonic generator 20b.
[0026]
9. The ultrasonic generators 20 a and 20 b generate ultrasonic waves traveling obliquely with respect to the surface of the measurement object 2 using the interference fringe scanning method, and wherein the ultrasonic wave generators 20 a and 20 b generate interference ultrasonic waves. The invention corresponds to the "ultrasonic wave generating means". Each of the ultrasonic generators 20a and 20b has a beam splitter 21, a mirror 22, and an acousto-optic element 23.
[0027]
The laser beams guided to the respective ultrasonic generators 20a and 20b are divided by the beam splitter 21 into a first laser beam L1 reflected by the beam splitter 21 and a second laser beam L2 transmitted through the beam splitter 21. . The first laser beam L1 is incident on the surface of the measuring object 2 as it is. On the other hand, the second laser beam L2 is reflected by the mirror 22 and then enters the acousto-optic device 23.
[0028]
The acousto-optic element 23 is an element using an acousto-optic effect (acousto-optic effect), and is used here as a frequency shifter. When an electric signal of an appropriate frequency is given to the acousto-optic element 23, the medium provided inside the acousto-optic element 23 performs ultrasonic vibration, and elastic strain and pressure change depending on the location. As a result, a change in the refractive index occurs in the medium, and when light from the outside enters the refractive index change region, the light is diffracted. At this time, the diffracted light undergoes a Doppler shift due to the ultrasonic vibration, and the frequency of the first-order diffracted light has a value shifted from the frequency of the original incident light by the frequency of the ultrasonic wave. Therefore, the frequency of the second laser beam L2 emitted from the acousto-optic element 23 is equal to the original frequency f.1Shift from The second laser beam L2 whose frequency has been shifted in this manner enters the surface of the measuring object 2. Here, the frequency of the second laser beam L2 whose frequency has shifted is represented by f2And
[0029]
Next, the interference fringe scanning method will be described. FIG. 3 is a diagram for explaining the principle of the interference fringe scanning method, and FIG. 4 is a diagram for explaining a specific configuration of each of the ultrasonic generators 20a and 20b in the residual stress distribution measuring device of the present embodiment. .
[0030]
Here, as shown in FIG. 3, the first laser beam L1 reflected by the beam splitter 21 has an angle (incident angle) θ with respect to the thickness direction of the measurement target 2 (the normal direction of the surface of the measurement target). Is assumed to be incident on the object 2 to be measured. On the other hand, the second laser beam L2 emitted from the acousto-optic element 23 has an angle (incident angle) θ from the side opposite to the first laser beam L1 with respect to the thickness direction of the measurement object 2, It is assumed that the light is incident on the same irradiation position as the irradiation position of the beam L1. That is, the first laser beam L1 and the second laser beam L2 irradiate the same position on the measurement target 2 at an angle 2θ to each other. Hereinafter, the position on the measurement target 2 to which the first laser beam L1 and the second laser beam L2 are irradiated is referred to as “ultrasonic generation position” or simply “generation position”. In the first ultrasonic generator 20a, the first laser beam L1 and the second laser beam L2 are located on the same plane perpendicular to the width direction of the measurement target 2, while the second ultrasonic generator 20b Here, it is assumed that the first laser beam L1 and the second laser beam L2 are in the same plane perpendicular to the rolling direction of the measuring object 2.
[0031]
In such a situation, the first laser beam L1 reflected by the beam splitter 21 and the second laser beam L2 emitted from the acousto-optic element 23 are applied to the same position (ultrasonic generation position) on the measurement target 2. Then, the two beams interfere with each other, and an interference fringe appears where light waves strengthen and weaken alternately. In addition, since the optical frequencies of the two laser beams L1 and L2 are slightly different, the interference fringes move on the surface of the measurement target 2. Here, the moving direction of the interference fringes is the rolling direction of the measurement target 2 when the first ultrasonic generator 20a generates the signal, and the moving direction of the interference fringe when the second ultrasonic generator 20b generates the interference fringe. In the width direction. Also, the scanning speed V of the interference fringesR, Interference fringe wavelength λacoIs
VR= Λ1・ (F2−f1) / 2 sin θ
λaco= Λ1/ 2 sin θ
Given by
[0032]
Since the interference fringes generated by the interference correspond to a pattern of thermal stress, an ultrasonic wave corresponding to the pattern is generated. The wavelength of this ultrasonic wave is the wavelength λ of the interference fringes.acoIs the same as In particular, the scanning speed V of the interference fringesRIs set to be greater than the sound speed of the ultrasonic wave inside the measurement target object 2, it is possible to generate an ultrasonic wave traveling obliquely to the surface of the measurement target object 2. At this time, longitudinal ultrasonic waves and transverse ultrasonic waves are simultaneously generated. Such an ultrasonic wave travels in a plane perpendicular to the width direction of the measurement object 2 when generated by the first ultrasonic generator 20a, and measured when generated by the second ultrasonic generator 20b. The object 2 travels in a plane perpendicular to the rolling direction. The shear wave generated by the first ultrasonic generator 20a is a shear wave displaced in the rolling direction, while the shear wave generated by the second ultrasonic generator 20b is a shear wave displaced in the width direction. is there. In the present embodiment, only longitudinal wave ultrasonic waves generated by the first ultrasonic wave generating unit 20a are considered, and those generated by the second ultrasonic wave generating unit 20b are not considered. That is, in the present embodiment, as the ultrasonic waves, the longitudinal waves generated by the first ultrasonic generator 20a, the transverse displacement transverse waves generated by the first ultrasonic generator 20a, and the second ultrasonic generator 20b Consider three of the transverse displacement transverse waves generated by. Also, the velocity of the longitudinal wave generated by the first ultrasonic generator 20a is VLAnd the velocity of sound of the transverse waveS1, The velocity of the transverse displacement transverse waveS2And
[0033]
The traveling direction angle (angle with respect to the thickness direction of the measuring object 2) at the time of generation of such an ultrasonic wave is φ, and the sound speed of the ultrasonic wave inside the measuring object 2 at that time is VCThen
φ = sin-1(VC/ VR)
There is a relationship. Therefore, the scanning speed V of the interference fringesRThat is, the incident angle θ or the frequency difference f2−f1Can be controlled to control the traveling direction angle φ at the time of generation of the ultrasonic wave. However, the sound speed V of the ultrasonic waveCHas a temperature dependence, so the surface temperature is measured, and V is determined based on the data on the relationship between the temperature and the sound speed measured in advance.CDecide.
[0034]
As will be described in detail later, in order to obtain the sound speed of the ultrasonic waves in each layer of the measurement object 2, the traveling direction angle at the time of generation of the ultrasonic waves is set in advance by the same number as the number of layers, and the setting is performed. Every time the ultrasonic wave is generated at each of the traveling direction angles, it is necessary to measure the propagation time until the ultrasonic wave generated at each of the traveling direction angles is reflected on the bottom surface of the measurement target 2 and returns to the surface again. There is. For this reason, it is necessary to control the traveling direction angle φ at the time of generation of the ultrasonic wave. In the present embodiment, such control is performed by adjusting the incident angle θ of the laser beam. Specifically, in order to easily adjust the incident angle θ, each of the ultrasonic generators 20a and 20b is configured as shown in FIG. That is, the first laser beam L1 reflected by the beam splitter 21 is perpendicularly incident on the surface of the measurement target 2. Further, a mirror 24 is provided for reflecting the second laser beam L2 emitted from the acousto-optic element 23 and irradiating the object 2 to be measured. Then, using a linear stage or the like, the position of the mirror 24 is adjusted along the rolling direction of the measurement target 2 in the first ultrasonic generation unit 20a, and the position of the measurement target 2 in the second ultrasonic generation unit 20b. By moving the second laser beam L2 along the width direction, the incident angle of the second laser beam L2 is controlled. Here, in FIG. 4, the actual incident angle of the second laser beam L2 is 2θ, but in the present embodiment, the half angle θ is also referred to as the incident angle.
[0035]
Incidentally, as a matter of course, the control of the traveling direction angle φ at the time of generation of the ultrasonic wave is performed by adjusting the incident angle of the first laser beam L1 instead of the second laser beam L2, or by controlling the first laser beam L1. This may be performed by adjusting the incident angles of both the beam L1 and the second laser beam L2.
[0036]
FIG. 5 shows an example of the setting value of the incident angle θ when the traveling direction angle φ at the time of generation of the longitudinal wave is controlled to 20, 30, 40, and 50 degrees. In this example, the frequency difference f2−f1Is set to 80 MHz. As shown in FIG. 5, the incident angle θ may be set to 0.14 degrees to set the traveling direction angle φ at the time of generation of the longitudinal wave to 20 degrees. When the traveling direction angle φ at the time of generation of the longitudinal wave is 30 degrees, the incident angle θ is 0.21 degrees, and when the traveling direction angle φ at the time of generation is 40 degrees, the incident angle θ is 0. It may be set to 26 degrees. Then, in order to set the traveling direction angle φ when the longitudinal wave is generated to 50 degrees, the incident angle θ may be set to 0.32 degrees.
[0037]
As can be seen from this example, since the set value of the incident angle θ is very small, the mirror 24 is usually installed at a position distant from the surface of the measurement target 2 to some extent, for example, at a position 4 m away. . The “beam interval” shown in the table of FIG. 5 is an interval between the first laser beam L1 and the second laser beam L2 measured at a height position 4 m away from the surface of the measurement target 2. Specifically, in order to set the traveling direction angle φ at the time of generation of a longitudinal wave to 20 degrees, the beam interval may be set to 9.8 mm. In addition, the beam interval is set to 14.4 mm to set the traveling direction angle φ when the longitudinal wave is generated to 30 degrees, and to 18.5 mm to set the traveling direction angle φ to 40 degrees when the longitudinal wave is generated. do it. Then, in order to set the traveling direction angle φ at the time of generation of a longitudinal wave to 50 degrees, the beam interval may be set to 22.0 mm.
[0038]
Since a transverse wave is generated simultaneously with the longitudinal wave, FIG. 5 also shows the traveling direction angle of the transverse wave generated simultaneously with the longitudinal wave. The reason why the traveling directions of the longitudinal wave and the shear wave are different is that the sound speed of the longitudinal wave and the sound speed of the shear wave are different inside the measurement object 2.
[0039]
Further, the position where the ultrasonic wave propagates inside the measurement object 2 and is reflected on the bottom surface thereof and returns to the surface again (hereinafter, referred to as “ultrasonic detection position” or simply “detection position”) is approximately. Can be predicted. As an example, FIG. 6 shows a relationship between a beam interval and a longitudinal wave detection candidate position. Here, the horizontal axis is the beam interval at a height position 4 m away from the surface of the measurement object 2, and the vertical axis is the longitudinal wave of the longitudinal wave measured from the incident position of the laser beams L1 and L2 along the rolling direction. This is a detection candidate position. Since the detection candidate position depends on the thickness of the measurement target 2, FIG. 6 shows a case where the thickness of the measurement target 2 is 30 mm and 50 mm, for example. Incidentally, the graph of FIG. 6 is obtained by assuming that the traveling direction of the longitudinal wave is constant inside the object 2 to be measured. However, in practice, the internal temperature of the measurement target 2 varies depending on the location, and the sound speed of the ultrasonic wave is not constant, so that the traveling direction of the ultrasonic wave changes inside the measurement target 2. Therefore, the longitudinal wave detection candidate position obtained by using the graph of FIG. 6 is different from the actual detection position. For this reason, in FIG. 6, the expression “detection candidate position” is used instead of the detection position. In the present embodiment, the relationship between the beam interval and the detection candidate position as shown in FIG. 6 is used as a reference for obtaining an actual ultrasonic detection position. Specifically, first, a detection position of an ultrasonic wave is found using a graph as shown in FIG. Next, by actually generating an ultrasonic wave, the intensity of the ultrasonic wave propagating in the measurement target object 2 is detected in an area around the detection candidate position. Then, the maximum intensity position is determined as the actual ultrasonic detection position.
[0040]
The ultrasonic generators 20a and 20b are integrally formed, and can move along the rolling direction and the width direction of the measurement target 2 on a plane parallel to the surface of the measurement target 2. The position information of each of the ultrasonic generators 20a and 20b is recognized by the computer 70, and the computer 70 determines the ultrasonic wave generation position in each of the ultrasonic generators 20a and 20b based on the position information of each of the ultrasonic generators 20a and 20b. You can know.
[0041]
The ultrasonic detection laser 30 is a laser for detecting an ultrasonic wave generated in the measurement target 2 by the irradiation of the laser beam from the ultrasonic generation laser 10 and transmitted through the measurement target 2. A laser that emits a single-frequency laser beam is used as the ultrasonic detection laser 30.
[0042]
The laser beam (third laser beam) L3 emitted from the ultrasonic detection laser 30 is split by the beam splitter 82 into two third laser beams L3. One of the branched third laser beams L3 is condensed by the condensing lens 86 and then enters the optical fiber 91. The optical fiber 91 guides the third laser beam L3 to the first beam acquisition unit 40a. The other third laser beam L3 branched by the beam splitter 82 is reflected by the mirror 84 and condensed by the condenser lens 87, and then enters the optical fiber 92. The optical fiber 92 guides the third laser beam L3 to the second beam acquisition unit 40b.
[0043]
Each of the beam acquisition units 40a and 40b guides the third laser beam L3 to a predetermined ultrasonic detection position, and acquires the third laser beam L3 reflected and scattered on the surface of the measurement target 2 in FIG. As shown in (1), there are two condenser lenses 41 and 42 and a half mirror 43. In particular, the first beam acquisition unit 40a guides the third laser beam L3 to the detection position of the longitudinal wave or the transverse wave generated by the first ultrasonic wave generation unit 20a, and the second beam acquisition unit 40b L3 is guided to the detection position of the shear wave generated by the first ultrasonic generator 20b. Each of the beam acquisition units 40a and 40b corresponds to "beam acquisition means" in the first aspect of the present invention.
[0044]
In addition, the beam acquisition units 40a and 40b are integrally formed, and can move along a rolling direction and a width direction of the measurement target 2 on a plane parallel to the surface of the measurement target 2. The position information of each beam acquisition unit 40a, 40b is recognized by the computer 70, and the computer 70 knows the ultrasonic detection position in each beam acquisition unit 40a, 40b based on the position information of each beam acquisition unit 40a, 40b. Can be.
[0045]
The third laser beam L3 incident on each of the beam acquisition units 40a and 40b is condensed by the condensing lens 41, passes through the half mirror 43, and irradiates a predetermined ultrasonic detection position on the measurement target object 2. . Since the surface of the measuring object 2 is rough, the third laser beam L3 is scattered almost isotropically on the surface of the measuring object 2. At this time, when the ultrasonic wave propagating inside the measurement object 2 returns to the detection position, the detection position vibrates at the detection position. Thereby, the frequency of the third laser beam L3 scattered on the surface of the measurement object 2 changes due to the Doppler shift caused by the ultrasonic vibration of the surface of the measurement object 2.
[0046]
A part of the third laser beam L3 scattered on the surface of the measurement object 2 is reflected by the half mirror 43 and then collected by the condenser lens. The third laser beam L3 condensed by the condenser lens 42 of the first beam acquisition unit 40a enters the optical fiber 93. The optical fiber 93 guides the third laser beam L3 to the first Fabry-Perot interferometer 50a. The third laser beam L3 emitted from the optical fiber 93 is incident on the first Fabry-Perot interferometer 50a after being condensed by the condenser lens 88. On the other hand, the third laser beam L3 condensed by the condensing lens 42 of the second beam acquisition unit 40b enters the optical fiber 94. The optical fiber 94 guides the third laser beam L3 to the second Fabry-Perot interferometer 50b. The third laser beam L3 emitted from the optical fiber 94 is condensed by the condenser lens 89, and then enters the second Fabry-Perot interferometer 50b.
[0047]
Each of the Fabry-Perot interferometers 50a and 50b detects a frequency change of the third laser beam L3 caused by the ultrasonic vibration, and has two reflecting mirrors 51 and 52 facing each other. The two reflecting mirrors 51 and 52 constitute a resonator, and function as a band-pass filter by multiple-reflecting the third laser beam L3 between the two reflecting mirrors 51 and 52. By adjusting the distance between the two reflecting mirrors 51 and 52, the frequency of light passing through this resonator can be adjusted. Each Fabry-Perot interferometer corresponds to the "frequency change detecting means" in the first aspect of the present invention.
[0048]
Here, the resonance curves in the Fabry-Perot interferometers 50a and 50b will be described. FIG. 7 is a diagram showing an example of this resonance curve. 7, the horizontal axis represents the frequency f of the incident light, and the vertical axis represents the output from the Fabry-Perot interferometers 50a and 50b, that is, the intensity I of the light transmitted through the Fabry-Perot interferometers 50a and 50b. . As can be seen from FIG. 7, the transmitted light intensity I shows a steep peak at a specific frequency, but rapidly decreases before and after the peak. The frequency showing this peak can be changed by adjusting the distance between the reflection mirrors 51, 52 of the Fabry-Perot interferometers 50a, 50b. Therefore, the distance between the reflection mirrors 51 and 52 is adjusted so that the frequency at the point (resonance curve operating point) A where the slope of the curve shown in FIG. 7 is the maximum coincides exactly with the oscillation frequency of the third laser beam L3. If so, a slight change in frequency ± Δf can be converted into a relatively large change in transmitted light intensity ± ΔI. Thereby, when the Fabry-Perot interferometers 50a and 50b receive the third laser beam L3 whose frequency has changed due to the Doppler shift caused by the ultrasonic vibration of the surface of the measuring object 2, the frequency changes. Is output as a change in transmitted light intensity.
[0049]
The transmitted light intensity output from the first Fabry-Perot interferometer 50a is sent to the first photodetector 60a, while the transmitted light intensity output from the second Fabry-Perot interferometer 50b is Sent to the vessel 60b. Each of the photodetectors 60a and 60b converts transmitted light intensity into an electric signal. Thereby, the ultrasonic vibration is finally caught as an electric signal. The signals from the photodetectors 60a and 60b are sent to the computer 70 and recorded as waveform data.
[0050]
In the present embodiment, the "ultrasonic detection means" in the invention according to claim 8 includes a first beam acquisition unit 40a, a first Fabry-Perot interferometer 50a, a first photodetector 60a, and a second beam acquisition unit. The unit 40b, the second Fabry-Perot interferometer 50b, and the second photodetector 60b correspond.
[0051]
Based on the waveform data, the computer 70 obtains a propagation time until the ultrasonic wave propagates inside the measurement target 2, reflects on the bottom surface thereof, and returns to the surface again. The timing at which a laser beam is emitted from the ultrasonic wave generation laser 10 and the timing at which the laser beam irradiates the measurement target 2 are known in advance. For this reason, the computer 70 can determine the propagation time of the ultrasonic wave by checking the timing at which the frequency change is detected based on the waveform data sent from each of the photodetectors 60a and 60b. Further, the computer 70 obtains the horizontal distance between the generation position and the detection position for each of the longitudinal wave and the transverse wave in the rolling direction based on the position information of the ultrasonic generator 20a and the position information of the beam acquisition unit 40a. At the same time, for the transverse displacement transverse wave, the horizontal distance between the generation position and the detection position is obtained based on the position information of the ultrasonic generator 20b and the position information of the beam acquisition unit 40b. That is, the computer 70 corresponds to the “calculating means” and the “distance calculating means” in the first or eighth aspect of the present invention.
[0052]
In the present embodiment, for each ultrasonic wave of longitudinal wave, rolling transverse wave, transverse transverse wave, the traveling direction angle at the time of generation thereof is set in advance by the same number as the number of layers of the measurement object 2 and the computer 70, for each ultrasonic wave, each time the first or second ultrasonic wave generating unit 20a, 20b generates an ultrasonic wave in each traveling direction angle, the propagation time and horizontal distance of the ultrasonic wave generated in the traveling direction are set. Ask. That is, for each ultrasonic wave of longitudinal wave, rolling transverse wave, transverse transverse wave, the traveling direction angle at the time of generation is controlled, and the above-described propagation time measurement process and horizontal distance calculation process are performed a predetermined number of times. repeat. Thereafter, the computer 70 determines, for each ultrasonic wave, the propagation time of the ultrasonic wave generated in each traveling direction angle and the horizontal distance between the generated position and the detected position of the ultrasonic wave generated in each traveling direction. Then, the sound speed of the ultrasonic wave in each layer of the measurement object 2 is calculated.
[0053]
Further, the computer 70 obtains the internal temperature of each layer of the measuring object 2 based on the calculated sound speed of the longitudinal wave in each layer. Here, the computer 70 is constructed with a database showing the correspondence between the internal temperature and the longitudinal wave velocity for various steel materials. Therefore, the computer 70 can easily obtain the internal temperature of each layer from the sound speed of the longitudinal wave in each layer of the measurement target 2 using the database.
[0054]
Next, a method of calculating the sound speed of the ultrasonic wave in each layer of the measurement target 2 from the propagation time and the horizontal distance of the ultrasonic wave generated in each traveling direction angle will be described in detail. 8 and 9 are diagrams for explaining a method of calculating the sound speed of the ultrasonic wave in each layer of the measurement target 2.
[0055]
In the case of a slab manufactured by a hot process, its internal temperature varies from place to place, and the sound speed of ultrasonic waves is not constant. For this reason, the traveling direction of the ultrasonic wave changes inside the thick plate. In the present embodiment, in the region of the measurement target 2 corresponding to the propagation region of the ultrasonic waves generated by the first or second ultrasonic generation units 20a and 20b, the sound speed of the ultrasonic wave is different for each layer of the measurement target 2. Is assumed to be constant within In this case, the smaller the thickness of each layer of the measuring object 2 is, the closer the assumed sound speed of the ultrasonic wave is to the actual value. Therefore, if the thickness of each layer is set sufficiently small, the internal temperature and the residual stress can be measured with high accuracy.
[0056]
Now, as shown in FIGS. 8 and 9, a case where the thick plate as the measurement target 2 is divided into four layers along the thickness direction will be considered. These layers are referred to as a first layer, a second layer, a third layer, and a fourth layer in order from the surface side of the thick plate. Here, the thickness of the k-th layer (k = 1, 2, 3, 4) is dk, Where the average sound speed of the ultrasonic wave is VkAnd And the traveling direction angle at the time of generation of the ultrasonic wave is φjWhen (j = 1, 2, 3, 4), the propagation time of the ultrasonic wave is tjAnd
[0057]
Further, under the above assumption, the traveling direction of the ultrasonic wave in each layer is constant, so it is necessary to consider that the ultrasonic wave is refracted when passing through the boundary surface of each layer as shown in FIG. However, in FIG. 8, such refraction is omitted, and the propagation path of the ultrasonic wave is shown by a straight line. Here, as shown in FIG. 9, the ultrasonic wave travels through the first layer of the measurement object 2 in the traveling direction angle φ.jWhen propagating at (j = 1, 2, 3, 4), the angle of refraction at the interface between the first and second layers is φj2, The angle of refraction at the interface between the second and third layers is φj3, The angle of refraction at the interface between the third and fourth layers is φj4And
[0058]
The ultrasonic wave travels through the first layer of the object 2 in the traveling direction angle φ.j(J = 1, 2, 3, 4), the propagation time t of the ultrasonic wavejIs
tj= 2 [d1/ (V1・ Cosφj) + D2/ (V2・ Cosφj2) + D3/ (V3・ Cosφj3) + D4/ (V4・ Cosφj4)]
It is. Here, applying Snell's law at each interface,
cosφjm= {1- (Vm/ V1)2(1-cos2φj)}1/2
≡F (V1, Vm, Cosφj)
It can be expressed as. Here, m = 2, 3, and 4. Therefore,
tj= 2 [d1/ (V1・ Cosφj)
+ D2/ (V2・ F (V1, V2, Cosφj))
+ D3/ (V3・ F (V1, V3, Cosφj))
+ D4/ (V4・ F (V1, V4, Cosφj)]
It becomes. Here, j = 1, 2, 3, and 4.
[0059]
These four propagation times t1, T2, T3, T4In the equation, the traveling direction angle φ when the ultrasonic wave is generated1, Φ2, Φ3, Φ4Is the parameter known from the interference fringe scanning method, and the thickness d of each layer1, D2, D3, D4I also know in advance. Therefore, the computer 70 calculates the propagation time t for the ultrasonic wave using the laser ultrasonic method.1, T2, T3, T4Is substituted into the above equations, and the sound speed V of the ultrasonic wave is1, V2, V3, V4By solving a nonlinear system of equations with unknown as the sound velocity, the sound velocity V of the ultrasonic wave in each layer1, V2, V3, V4Is calculated.
[0060]
Here, since the system of equations to be solved is nonlinear, the solution is not unique, and the sound velocity V of the ultrasonic wave in each layer is different.1, V2, V3, V4And a plurality of sets of solutions are obtained. For this reason, the computer 70 determines that each traveling direction angle φjThe horizontal distance x between the generation position and the detection position of the ultrasonic wave generated at (j = 1, 2, 3, 4)jIs used as a determination formula for selecting an appropriate set of solutions from a plurality of sets of solutions. Horizontal distance xjThe equation representing (j = 1, 2, 3, 4) is
xj= 2 [d1・ Tanφj+ D2・ Tanφj2+ D3・ Tanφj3+ D4・ Tanφj4]
Given by Here, according to Snell's law,
tanφjm= (Vm/ V1) (1-cos2φj)1/2× {1- (Vm/ V1)2(1-cos2φj)}-1/2
It is. Here, m = 2, 3, and 4. The computer 70 first calculates the horizontal distance x of the ultrasonic wave obtained based on the position information of the ultrasonic wave generating unit and the position information of the beam acquiring unit in an expression representing the four horizontal distances.1, X2, X3, X4Is assigned. Then, in these equations, the four propagation times t1, T2, T3, T4By substituting the solution of each set obtained by solving the equation (1), it is determined whether or not the equation representing the four horizontal distances is satisfied. Then, a set of solutions that satisfies the equations representing the four horizontal distances is defined as the sound velocity V of the ultrasonic wave in each layer.1, V2, V3, V4To be determined.
[0061]
Actually, the computer 70 obtains the sound velocity of the ultrasonic wave in each layer using dedicated nonlinear regression calculation software. As such dedicated nonlinear regression calculation software, for example, software created using a Levenberg-Marquardt algorithm module can be used.
[0062]
In this way, for each of the longitudinal wave, rolling direction displacement transverse wave, and width direction displacement transverse wave, the sound velocity of the ultrasonic wave in each layer of the measurement object 2 is calculated, so that the sound velocity distribution inside the measurement object 2 is calculated. Obtainable. Further, the internal temperature of each layer can be obtained based on the speed of sound of the longitudinal wave in each layer. Therefore, the computer 70 obtains the residual stress of each layer near the ultrasonic irradiation position by calculating the internal temperature in each layer and the sound speed of each ultrasonic wave in each layer by substituting into an equation using the sound velocity ratio method. be able to.
[0063]
Next, a procedure for measuring the residual stress distribution of the measurement object 2 in the residual stress distribution measuring device of the present embodiment will be described. FIG. 10 is a flowchart for explaining a procedure for measuring the residual stress distribution of the measuring object 2 in the residual stress distribution measuring device.
[0064]
First, the operator sets the number of layers that divide the measurement object 2 along the thickness direction, the thickness of each layer, and the longitudinal wave, rolling direction displacement transverse wave, width direction displacement generated by the interference fringe scanning method. For each of the transverse waves, the traveling direction angle is set by the same number as the number of layers (S1). Then, the operator inputs these set values and parameter values necessary for calculation to the computer 70 (S2).
[0065]
Next, the propagation time is measured for each of the ultrasonic waves of the longitudinal wave, the transverse wave in the rolling direction, and the transverse wave in the width direction (S3). In the present embodiment, by providing two sets of the ultrasonic wave generating unit and the beam acquiring unit, it is possible to simultaneously measure the propagation times of the two ultrasonic waves. For example, a propagation time of a longitudinal wave and a propagation time of a transverse displacement transverse wave are simultaneously measured, and thereafter, a propagation time of a rolling displacement transverse wave is measured.
[0066]
Specifically, first, the operator selects one traveling direction angle from the plurality of traveling direction angles set in step S1 for the longitudinal wave, and also selects one traveling direction angle for the widthwise displacement transverse wave. . Then, the position of the mirror 24 in the first ultrasonic generator 20a is adjusted so that a longitudinal wave is generated at the selected longitudinal wave traveling direction angle, and a transverse wave is generated at the selected transverse wave traveling direction angle. To adjust the position of the mirror 24 in the second ultrasonic generator 20b. Then, by actually emitting a laser beam from the ultrasonic wave generation laser 10 with reference to the relationship between the beam interval and the detection candidate position as shown in FIG. 6, the first ultrasonic wave is generated by the first ultrasonic wave generation unit 20a. The actual detection position of the longitudinal wave and the actual detection position of the shear wave generated by the second ultrasonic generator 20b are detected. Then, the position of the first beam acquisition unit 40a is adjusted such that the third laser beam L3 emitted from the ultrasonic detection laser 30 is irradiated to the detection position of the longitudinal wave, and the third laser beam L3 is The position of the second beam acquisition unit 40b is adjusted so that the detection position of the transverse wave is emitted.
[0067]
After the position is adjusted in this manner, the computer 70 generates a longitudinal wave generated in the selected traveling direction based on the position information of the first ultrasonic wave generating unit 20a and the position information of the first beam acquiring unit 40a. Find the horizontal distance between the position and the detection position. In addition, based on the position information of the second ultrasonic wave generating unit 20b and the position information of the second beam acquiring unit 40b, the position between the occurrence position and the detection position of the transverse displacement transverse wave generated at the selected traveling direction angle is determined. Find the horizontal distance of These horizontal distances are stored in a predetermined memory of the computer 70.
[0068]
When the preparation is completed in this way, next, a laser beam is emitted from the ultrasonic wave generation laser 10 to generate an ultrasonic wave inside the measurement object 2, and a third laser beam is emitted from the ultrasonic wave detection laser 30. Accordingly, the first beam acquisition unit 40a and the first Fabry-Perot interferometer 50a detect a frequency change of the third laser beam caused by the vibration of the longitudinal ultrasonic wave, and the second beam acquisition unit 40b The second Fabry-Perot interferometer 50b detects a frequency change of the third laser beam caused by the vibration of the ultrasonic wave of the widthwise displacement transverse wave. Then, the computer 70 obtains the propagation time of the longitudinal wave and the propagation time of the transverse displacement lateral wave based on the waveform data representing the frequency change. These propagation times are stored in a predetermined memory of the computer 70.
[0069]
Next, by repeating the above processing for all traveling direction angles set in step S1, the propagation time of the longitudinal wave generated in each traveling direction angle, the generation position of the longitudinal wave generated in each traveling direction The horizontal distance between the position and the detection position, the propagation time of the transverse displacement transverse wave generated in each traveling direction, and the horizontal distance between the occurrence position and the detection position of the transverse displacement transverse wave generated in each traveling direction are obtained. .
[0070]
Thereafter, similarly, using the first ultrasonic wave generating unit 20a, the first beam acquiring unit 40a, and the first Fabry-Perot interferometer 50a, the generation position and the detection of the rolling direction displacement transverse wave generated at each traveling direction angle are detected. The horizontal distance from the position is determined, and the propagation time of the transverse displacement transverse wave generated at each traveling direction angle is measured. In this way, for each of the ultrasonic waves of the longitudinal wave, the transverse wave in the rolling direction, and the transverse wave in the width direction, the horizontal distance and the propagation time when the ultrasonic waves are generated at each traveling direction angle are obtained.
[0071]
Next, the computer 70 measures based on the propagation time of each ultrasonic wave generated in each traveling direction angle and the horizontal distance between the generated position and the detected position for each ultrasonic wave generated in each traveling direction angle. The sound speed of the longitudinal wave, the sound speed of the transverse wave in the rolling direction, and the sound speed of the transverse wave in the width direction in each layer of the object 2 are calculated (S4). Thereafter, the computer 70 obtains the internal temperature of each layer from the sound speed of the longitudinal wave in each layer of the measurement object 2 using a database indicating the correspondence between the internal temperature and the longitudinal wave speed of the measurement object 2 (S5). ). Then, the computer 70 calculates the residual temperature (the stress in the rolling direction) in each layer in the vicinity of the ultrasonic irradiation position by calculating the internal temperature in each layer and the sound speed of each ultrasonic wave by substituting it into an equation using the sound velocity ratio method. And the stress in the width direction). The residual stress of each layer thus obtained is displayed on a screen of the computer 70, for example.
[0072]
Next, the present inventors verified whether the sound speed of ultrasonic waves in each layer can be obtained with sufficient accuracy using the residual stress distribution measurement device of the present embodiment. This verification was performed as follows. First, the internal temperature of each layer is assumed. Then, based on the assumed internal temperature of each layer, the sound velocity of the ultrasonic wave in each layer is determined using a database indicating the correspondence between the internal temperature and the sound velocity of the ultrasonic wave (here, a longitudinal wave). Then, using the sound speed of the ultrasonic waves in each of these layers, data on the propagation time and data on the horizontal distance for the ultrasonic waves generated in each traveling direction angle are created. Next, the created propagation time data and horizontal distance data are input to the computer 70. The computer 70 calculates the sound speed of the ultrasonic wave in each layer using dedicated nonlinear regression calculation software. Then, it was examined whether or not the sound speed of the ultrasonic wave calculated in each layer coincides with the sound speed of the ultrasonic wave obtained from the initially assumed internal temperature.
[0073]
FIG. 11 is a diagram illustrating an example of various data created when verifying a method of calculating the sound speed of the ultrasonic wave in each layer. In this verification, it was assumed that the number of layers was 6, and the thickness of each layer was 5 mm. Then, as shown in FIG. 11, the internal temperature of the first layer is 775 ° C., the internal temperature of the second layer is 790 ° C., the internal temperature of the third layer is 830 ° C., the internal temperature of the fourth layer is 810 ° C. The internal temperature of the fifth layer was assumed to be 850 ° C, and the internal temperature of the sixth layer was assumed to be 770 ° C. Further, the traveling direction angle φ at which the ultrasonic wave propagates through the first layerj(J = 1, 2,..., 6) were assumed to be 15, 20, 25, 30, 35, and 40 degrees, respectively.
[0074]
After assuming such various data, first, the sound velocity of the ultrasonic wave in each layer was obtained from the assumed internal temperature of each layer using a database indicating the correspondence between the internal temperature and the sound velocity of the ultrasonic wave. Specifically, as shown in FIG. 11, the sound speed of the ultrasonic wave in the first layer is 6008.38 m / sec, the sound speed of the ultrasonic wave in the second layer is 5864.15 m / sec, and the sound speed of the ultrasonic wave in the third layer Is 5479.55 m / sec, the sound speed of the ultrasonic wave in the fourth layer is 5671.85 m / sec, the sound speed of the ultrasonic wave in the fifth layer is 5287.25 m / sec, and the sound speed of the ultrasonic wave in the sixth layer is 6056.45 m / sec. sec.
[0075]
Next, using the sound speed of the ultrasonic waves in each of these layers, the traveling direction angle is φjWhen (j = 1, 2,..., 6), the time required for the ultrasonic wave to propagate through each layer (propagation time in each layer) was determined. The propagation time in each such layer is shown in FIG. After that, each traveling direction angle φjThe (total) propagation time of the ultrasonic wave generated at (j = 1, 2,..., 6) and the horizontal distance between the generation position and the detection position were determined. As shown in FIG. 11, the traveling direction angle is φ1, The ultrasonic wave propagation time is 1.083 × 10-5sec, the horizontal distance between the occurrence position and the detection position is 1.5280 × 10-2m. The traveling direction angle is φ2, The propagation time of the ultrasonic wave is 1.111 × 10-5sec, the horizontal distance between the occurrence position and the detection position is 2.0704 × 10-2m. The traveling direction angle is φ3, The propagation time of the ultrasonic wave is 1.147 × 10-5sec, the horizontal distance between the occurrence position and the detection position is 2.6433 × 10-2m. The traveling direction angle is φ4, The propagation time of the ultrasonic wave is 1.194 × 10-5sec, the horizontal distance between the occurrence position and the detection position is 3.2577 × 10-2m. The traveling direction angle is φ5, The propagation time of the ultrasonic wave is 1.254 × 10-5sec, the horizontal distance between the occurrence position and the detection position is 3.9269 × 10-2m. The traveling direction angle is φ6, The propagation time of the ultrasonic wave is 1.329 × 10-5sec, the horizontal distance between the occurrence position and the detection position is 4.6682 × 10-2m.
[0076]
Thus, based on the assumed internal temperature, each traveling direction angle φj(J = 1, 2,..., 6), the data of the propagation time of the ultrasonic wave and the data of the horizontal distance between the generation position and the detection position are obtained, and then the propagation of these ultrasonic waves is performed. The time data and the horizontal distance data were input to the computer 70 as measured values. Then, the computer 70 calculated the sound speed of the ultrasonic wave in each layer using dedicated nonlinear regression software. In this verification, as the nonlinear regression software used in the computer 70, software created using the above-described Levenberg-Marquardt algorithm module was used. Here, the traveling direction angle when generating ultrasonic waves is φjWhen (j = 1, 2,..., 6, 6), the FITTING evaluation expression for regression calculation is
Δj = {(xjCAL-XjMES) / XjINIT2+ {(TjCAL-TjMES) / TjINIT2And The subscript “CAL” indicates a calculated value in the regression calculation. The subscript “MES” indicates the input measurement value, and the subscript “INIT” indicates an initial value (provisional estimated value) in the regression calculation.
[0077]
As a result of the calculation, the sound speed of the ultrasonic wave in the first layer is 6.00097 × 103m / sec, and the sound velocity of the ultrasonic wave in the second layer is 5.8225 × 103m / sec, the acoustic velocity of the ultrasonic wave in the third layer is 5.5441 × 103m / sec, the sound velocity of the ultrasonic wave in the fourth layer is 5.6373 × 103m / sec, and the sound speed of the ultrasonic wave in the fifth layer is 5.2625 × 103m / sec, the sound velocity of the ultrasonic wave in the sixth layer was 6.0967 × 103m / sec was obtained.
[0078]
Comparing the sound speed of the ultrasonic wave (calculated sound speed value) in each layer obtained by this calculation with the sound speed of the ultrasonic wave (assumed sound speed value) in each layer first obtained in FIG. 11, the calculated sound speed value and the assumed sound speed value in each layer Is about 1%. Therefore, by using the residual stress distribution measuring device of the present embodiment, the sound speed of the ultrasonic waves in each layer, that is, the residual stress can be obtained with sufficient accuracy.
[0079]
In the residual stress distribution measuring apparatus of the present embodiment, by using a laser ultrasonic method and an interference fringe scanning method, an ultrasonic wave which travels obliquely with respect to the surface is generated inside the object to be measured, and longitudinal waves, rolling With respect to each ultrasonic wave of the directional displacement transverse wave and the width direction displacement transverse wave, a propagation time when the ultrasonic wave is generated in each of a plurality of traveling directions is obtained. Further, the horizontal distance between the position where the ultrasonic wave is generated in each traveling direction and the position where the ultrasonic wave is detected is determined. Then, for each ultrasonic wave, based on the plurality of obtained propagation times and horizontal distances, after calculating the sound speed in each layer of the measurement object pre-divided along the thickness direction, the sound speed of the longitudinal wave in each layer is calculated. The internal temperature of each layer is obtained based on the sound velocity of each layer for each ultrasonic wave, and the residual stress of each layer is calculated based on the internal temperature of each layer. Therefore, the residual stress distribution of the measurement object can be directly obtained by using the residual stress distribution measuring device of the present embodiment. In particular, since the laser ultrasonic method and the interference fringe scanning method are used, the residual stress distribution of the measurement object can be obtained online hot.
[0080]
Note that the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist.
[0081]
In the above embodiment, the case where the internal temperature of the measurement target is determined based on the sound velocity of the longitudinal wave has been described. However, the internal temperature of the measurement target may be determined based on the sound velocity of the shear wave. In this case, it is necessary to build in the computer a database of the correspondence between the internal temperature and the sound speed of the shear wave for various steel materials.
[0082]
Further, in the above embodiment, the case where the measurement target is divided into four layers along the thickness direction and the internal temperature of each layer is measured has been described. And the internal temperature and residual stress of each layer may be measured. In particular, as the number of layers to be divided increases, the accuracy of measuring the temperature distribution and the residual stress distribution inside the object to be measured improves. For this reason, it is necessary to determine the number of layers that divide the measurement object in consideration of the measurement accuracy.
[0083]
Further, in the above-described embodiment, the case where two sets of the ultrasonic generator, the beam acquisition unit, the Fabry-Perot interferometer, and the photodetector are provided is described. However, only one set of these components may be provided. Good. In this case, the propagation time for each of the ultrasonic waves of the longitudinal wave, the transverse wave in the rolling direction, and the transverse wave in the width direction is individually measured. Alternatively, three sets of such components may be provided. Thereby, the propagation time of each ultrasonic wave can be measured at once.
[0084]
Furthermore, in the above embodiment, the case where a thick plate manufactured by a hot process is used as the measurement target has been described, but the residual stress distribution measuring device of the present invention is not limited to any object other than such a thick plate. It can also be applied to
[0085]
Further, in the above embodiment, the ultrasonic wave is generated inside the object to be measured by using a laser ultrasonic method, and the ultrasonic wave is generated, and is reflected on the bottom surface of the object to be returned to the surface again. Although the case where the detected ultrasonic wave is detected has been described, for example, it is also possible to generate and detect the ultrasonic wave using a probe. FIG. 12 is a schematic configuration diagram of a residual stress distribution measuring device according to a modification of the present invention.
[0086]
The residual stress distribution measuring device shown in FIG. 12 includes a first probe 110, a second probe 120, a flaw detector 130, and a computer 140. The first probe 110 generates an ultrasonic wave that travels obliquely with respect to the surface of the object 2 to be measured. Here, the first probe 110 generates a longitudinal ultrasonic wave, a transverse ultrasonic wave displaced in the longitudinal direction of the measuring object 2, and a lateral ultrasonic wave displaced in the transverse direction of the measuring object 2. Let it. The second probe 120 receives, for each of the ultrasonic waves generated by the first probe 110, the ultrasonic waves reflected on the bottom surface of the measurement target 2 and returned to the surface again, and This is for detecting ultrasonic waveform data. Each of the first probe 110 and the second probe 120 can move on the surface of the measurement target 2. The movement of the two probes 110 and 120 is controlled by the computer 140. The position information of each of the probes 110 and 120 is recognized by the computer 140, and the computer 140 can know the ultrasonic generation position and the ultrasonic detection position based on the position information of each of the probes 110 and 120. The first probe 110 corresponds to “ultrasonic wave generating means” in the invention described in claim 8, and the second probe 120 corresponds to “ultrasonic wave detecting means” in the invention described in claim 8. I do.
[0087]
The flaw detector 130 includes an occurrence control unit 131, a data processing unit 132, a storage unit 133, and a waveform display unit 134. The generation control unit 131 controls generation of ultrasonic waves by the first probe 110. Specifically, it controls the timing of the generation of ultrasonic waves and the energy and waveform of the generated ultrasonic waves. The data processing unit 132 amplifies the ultrasonic waveform data detected by the second probe 120 and removes noise. The waveform data processed by the data processing unit 132 is stored in the storage unit 133. The waveform display unit 134 displays waveform data.
[0088]
It should be noted that commercially available probes 110 and 120 and flaw detector 130 can be used.
[0089]
The computer 140 has the same function as the computer 70 in the above embodiment, and corresponds to the “distance calculating means” and the “calculating means” in the invention described in claim 8. Also in this modification, the measurement object 2 is divided into a plurality of layers along the thickness direction. Then, for each of the ultrasonic waves of the longitudinal wave, the displacement wave in the longitudinal width direction, and the transverse wave in the width direction, the traveling direction angle of the ultrasonic wave in the first layer of the measurement object 2 is equal to the number of layers of the measurement object 2. It is set in advance. Each time the first probe 110 generates the ultrasonic wave at each traveling direction angle for each ultrasonic wave, the computer 140 calculates the propagation time of the ultrasonic wave generated at the traveling direction angle and calculates the traveling direction of the ultrasonic wave. The horizontal distance between the position where the ultrasonic wave generated at the angle is generated and the detected position is determined. Thereafter, the computer 140 calculates, for each ultrasonic wave, the propagation time of the ultrasonic wave generated at each traveling direction angle, the horizontal distance between the generated position and the detected position of the ultrasonic wave generated at each traveling direction angle, and , The sound speed of the ultrasonic wave in each layer of the measurement object 2 is calculated. Further, the computer 140 obtains the internal temperature in each layer of the measurement object 2 based on the calculated sound speed of the longitudinal wave in each layer, and calculates the residual stress in each layer based on the sound speed of each ultrasonic wave in each layer and the internal temperature of each layer. calculate.
[0090]
In the residual stress distribution measuring device according to the modified example, the method of calculating the traveling direction angle of the ultrasonic wave in the first layer is different from that in the above embodiment. That is, the ultrasonic waves generated from the first probe 110 are refracted at the interface between the first probe 110 and the measurement target 2 and enter the measurement target 2. At this time, the traveling direction angle of the ultrasonic wave in the first layer (the refraction angle at the boundary surface) includes the incident angle of the ultrasonic wave to the boundary surface, the sound speed of the ultrasonic wave propagating outside the measurement object 2, and the measurement object. Calculated from Snell's law using the sound speed of the ultrasonic wave propagating in the surface layer of No. 2. Here, the sound speed of the ultrasonic wave propagating through the surface layer of the measurement target 2 can be determined from the measured surface temperature of the measurement target 2.
[0091]
Even in the residual stress distribution measuring device of such a modified example, the residual stress distribution of the object to be measured can be directly measured similarly to the residual stress distribution measuring device in the above embodiment. However, since ultrasonic waves are generated and detected using the probe, the residual stress distribution measuring device of the modified example is not suitable for use in measuring the residual stress distribution of the object to be measured online hot.
[0092]
【The invention's effect】
As described above, in the residual stress distribution measuring device of the present invention, an ultrasonic wave that travels obliquely to the surface of the object to be measured is generated inside the object to be measured, and the longitudinal wave, the longitudinal displacement transverse wave, and the transverse displacement transverse wave are generated. For each ultrasonic wave, a propagation time when the ultrasonic wave is generated in each of a plurality of traveling directions is obtained. Further, the distance between the position where the ultrasonic wave is generated in each traveling direction and the detection position is obtained. Then, for each ultrasonic wave, after calculating the sound velocity in each layer of the measurement object pre-divided along the thickness direction based on the distance between the obtained plurality of propagation times and the occurrence position and the detection position, The internal temperature of each layer is obtained based on the sound speed of each layer for one ultrasonic wave, and the residual stress of each layer is calculated based on the sound speed of each layer and the internal temperature of each layer for each ultrasonic wave. Therefore, the residual stress distribution of the measurement object can be directly obtained by using the residual stress distribution measuring device of the present invention. In particular, by using the laser ultrasonic method and the interference fringe scanning method, the residual stress distribution of the object to be measured can be obtained online hot.
[0093]
Further, according to the residual stress distribution measuring method of the present invention, the residual stress distribution of the object to be measured can be directly obtained in the same manner as described above. In particular, by using the laser ultrasonic method and the interference fringe scanning method, the residual stress distribution of the object to be measured can be obtained online hot.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a residual stress distribution measuring device according to an embodiment of the present invention.
FIG. 2 is a graph showing a relationship between an internal temperature and a longitudinal wave velocity for a steel material.
FIG. 3 is a diagram for explaining the principle of the interference fringe scanning method.
FIG. 4 is a diagram for explaining a specific configuration of each ultrasonic generator in the residual stress distribution measuring device of the present embodiment.
FIG. 5 is a diagram illustrating an example of a setting value of an incident angle θ of a laser beam when controlling a traveling direction angle φ when a longitudinal wave is generated.
FIG. 6 is a graph showing a relationship between a beam interval and a longitudinal wave detection candidate position.
FIG. 7 is a diagram showing an example of a resonance curve of a Fabry-Perot interferometer in the residual stress distribution measuring device of the present embodiment.
FIG. 8 is a diagram for explaining a method of calculating the sound speed of an ultrasonic wave in each layer of a measurement object.
FIG. 9 is a diagram for explaining a method of calculating a sound speed of an ultrasonic wave in each layer of a measurement object.
FIG. 10 is a flowchart for explaining a procedure for measuring a residual stress distribution of a measurement object in the residual stress distribution measuring device of the present embodiment.
FIG. 11 is a diagram illustrating an example of various data created when verifying a method of calculating the sound speed of an ultrasonic wave in each layer.
FIG. 12 is a schematic configuration diagram of a residual stress distribution measuring device according to a modification of the present invention.
[Explanation of symbols]
2) Object to be measured
Laser for generating 10 ° ultrasonic waves
20a @ first ultrasonic generator
20b @ second ultrasonic generator
21 ° beam splitter
22, 24 mirror
23 acousto-optic device
30 ° ultrasonic detection laser
40a @ First beam acquisition unit
40b @ second beam acquisition unit
41, 42 condenser lens
43 half mirror
50a @ 1st Fabry-Perot interferometer
50b II second Fabry-Perot interferometer
51, 52 reflection mirror
60a @ First photodetector
60b @ 2nd photodetector
70 computer
81,82 beam splitter
84mm mirror
86, 87, 88, 89 condenser lens
91, 92, 93, 94 optical fiber
110 ° first probe
120 ° second probe
130 flaw detector
131 generation control unit
132 Data processing unit
133 storage unit
134 ° waveform display
140 computer

Claims (11)

  1. A residual stress distribution measurement device that divides a plate-shaped measurement target into a plurality of layers along its thickness direction, and measures a residual stress of each layer at a predetermined position on a surface of the measurement target,
    By irradiating the first laser beam and the second laser beam having different frequencies to the same position (ultrasonic generation position) of the measurement object at a predetermined incident angle, the first laser beam and the second laser beam Causes an ultrasonic wave that travels obliquely to the surface of the measurement object, inside the measurement object, and is movable along a plane parallel to the surface of the measurement object. Constituted ultrasonic generating means,
    For each of the longitudinal ultrasonic wave generated by the ultrasonic wave generating means, the transverse ultrasonic wave displaced in the vertical width direction of the measurement object, and the transverse ultrasonic wave displaced in the horizontal width direction of the measurement object, A third laser beam is guided to a position (ultrasonic detection position) where the sound wave is reflected on the bottom surface of the measurement object and returns to the surface again, and the third laser beam reflected on the surface of the measurement object is obtained. Beam acquisition means configured to be movable along a plane parallel to the surface of the measurement object,
    Distance calculation means for obtaining a distance between the ultrasonic wave generation position and the ultrasonic wave detection position for the ultrasonic wave based on the position information of the ultrasonic wave generation means and the position information of the beam acquisition means,
    Based on the third laser beam acquired by the beam acquisition unit, a frequency change detection unit that detects a change in the frequency of the third laser beam caused by the vibration of the ultrasonic wave,
    An arithmetic unit for calculating a propagation time during which the ultrasonic wave has propagated inside the measurement target based on waveform data representing a frequency change of the third laser beam detected by the frequency change detection unit,
    The traveling direction at the time of generation of each of the ultrasonic waves is set in advance by the same number as the number of the layers, and the distance calculating means determines that each of the ultrasonic waves is generated by the ultrasonic generation means for each of the ultrasonic waves. Each time the ultrasonic wave is generated in the direction, the distance between the ultrasonic wave generation position and the ultrasonic wave detection position is obtained, and the calculating means calculates, for each ultrasonic wave, the ultrasonic wave generation means Each time the ultrasonic wave is generated, the propagation time of the ultrasonic wave generated in the traveling direction is obtained, and the propagation time of the ultrasonic wave generated in the traveling direction and the traveling direction obtained by the distance calculating means. Calculate the sound speed of the ultrasonic wave in each layer based on the distance between the ultrasonic wave generation position and the ultrasonic wave detection position for the ultrasonic wave generated, and the calculated one in each layer Super A residual stress distribution measuring device, wherein the internal temperature of each layer is obtained based on the sound velocity of a wave, and the residual stress of each layer is calculated based on the sound velocity of each ultrasonic wave and the internal temperature of each layer in each layer. .
  2. The first laser beam and the second laser beam are obtained by branching a single laser beam generated from one laser device into two, and causing one of the branched laser beams to enter the acousto-optic element. The residual stress distribution measuring device according to claim 1, which is obtained.
  3. The ultrasonic wave generating means controls a traveling direction at the time of generation of each ultrasonic wave by adjusting an incident angle of at least one of the first laser beam and the second laser beam. The residual stress distribution measuring device according to claim 1.
  4. 4. The residual stress distribution measuring device according to claim 1, wherein two sets of said ultrasonic wave generating means, said beam obtaining means and said frequency detecting means are provided.
  5. A residual stress distribution measurement method for dividing a plate-shaped measurement target into a plurality of layers along a thickness direction thereof, and measuring a residual stress of each layer at a predetermined position on a surface of the measurement target,
    By irradiating the first laser beam and the second laser beam having different frequencies to the same position (ultrasonic generation position) of the measurement object at a predetermined incident angle, the first laser beam and the second laser beam The first step of generating ultrasonic waves that travel obliquely with respect to the surface of the measurement object, inside the measurement object,
    The third laser beam is guided to a position (ultrasonic detection position) where the ultrasonic wave is reflected on the bottom surface of the measurement object and returns to the surface again, and the third laser reflected on the surface of the measurement object. A second step of obtaining a beam;
    A third step of determining the distance between the ultrasonic wave generation position and the ultrasonic detection position for the ultrasonic wave,
    Based on the third laser beam obtained in the second step, based on the vibration of the ultrasonic wave, a fourth step of detecting a change in the frequency of the third laser beam,
    A fifth step of determining a propagation time during which the ultrasonic wave has propagated inside the measurement target based on waveform data representing a frequency change of the third laser beam detected in the fourth step,
    For each of the longitudinal ultrasonic wave generated in the first step, the transverse ultrasonic wave displaced in the vertical width direction of the measurement object, and the transverse ultrasonic wave displaced in the horizontal width direction of the measurement object, The traveling direction is set in advance by the same number as the number of the layers, the ultrasonic waves are sequentially generated in the set traveling directions, and the first to fifth steps are repeated. For each ultrasonic wave, the distance between the ultrasonic wave generation position and the ultrasonic detection position for the ultrasonic wave generated in each traveling direction and the propagation time of the ultrasonic wave generated in each traveling direction. The sixth step to seek,
    For each ultrasonic wave, based on the propagation time of the ultrasonic wave generated in each traveling direction and the distance between the ultrasonic wave generation position and the ultrasonic detection position for the ultrasonic wave generated in each traveling direction. A seventh step of calculating the sound speed of the ultrasonic wave in each of the layers,
    An eighth step of determining the internal temperature of each layer based on the sound speed of the one ultrasonic wave in each layer calculated in the seventh step,
    A ninth step of calculating the residual stress of each layer based on the speed of sound of each ultrasonic wave in each layer and the internal temperature of each layer,
    A method for measuring a residual stress distribution, comprising:
  6. The first laser beam and the second laser beam are obtained by branching a single laser beam generated from one laser device into two, and causing one of the branched laser beams to enter the acousto-optic element. The residual stress distribution measuring method according to claim 5, which is obtained.
  7. In the first step, by adjusting the incident angle of at least one of the first laser beam and the second laser beam, to control the traveling direction at the time of the generation of each ultrasonic wave. The residual stress distribution measuring method according to claim 5 or 6, wherein
  8. A residual stress distribution measurement device that divides a plate-shaped measurement target into a plurality of layers along its thickness direction, and measures a residual stress of each layer at a predetermined position on a surface of the measurement target,
    At a predetermined position (ultrasonic generation position) on the surface of the measurement object, an ultrasonic wave that proceeds obliquely with respect to the surface of the measurement object is generated inside the measurement object, and Ultrasonic wave generation means configured to be movable along a plane parallel to the surface,
    For each of the longitudinal ultrasonic wave generated by the ultrasonic wave generating means, the transverse ultrasonic wave displaced in the vertical width direction of the measurement object, and the transverse ultrasonic wave displaced in the horizontal width direction of the measurement object, The ultrasonic wave is detected at a position (ultrasonic detection position) where the sound wave is reflected on the bottom surface of the measurement object and returns to the surface again, and is movable along a plane parallel to the surface of the measurement object. Configured ultrasound detection means,
    Based on the position information of the ultrasonic wave generating means and the position information of the ultrasonic wave detecting means, distance calculating means for calculating the distance between the ultrasonic wave generating position and the ultrasonic wave detecting position for the ultrasonic wave,
    Calculating means for calculating a propagation time during which the ultrasonic wave has propagated inside the object to be measured, based on waveform data of the ultrasonic wave obtained by the ultrasonic detecting means,
    The traveling direction at the time of generation of each of the ultrasonic waves is set in advance by the same number as the number of the layers, and the distance calculating means determines that each of the ultrasonic waves is generated by the ultrasonic generation means for each of the ultrasonic waves. Each time the ultrasonic wave is generated in the direction, the distance between the ultrasonic wave generation position and the ultrasonic wave detection position is obtained, and the calculating means calculates, for each ultrasonic wave, the ultrasonic wave generation means Each time the ultrasonic wave is generated, the propagation time of the ultrasonic wave generated in the traveling direction is obtained, and the propagation time of the ultrasonic wave generated in the traveling direction and the traveling direction obtained by the distance calculating means. Calculate the sound speed of the ultrasonic wave in each layer based on the distance between the ultrasonic wave generation position and the ultrasonic wave detection position for the ultrasonic wave generated, and the calculated one in each layer Super A residual stress distribution measuring device, wherein the internal temperature of each layer is obtained based on the sound velocity of a wave, and the residual stress of each layer is calculated based on the sound velocity of each ultrasonic wave and the internal temperature of each layer in each layer. .
  9. 9. The residual stress distribution measuring apparatus according to claim 8, wherein a probe is used as each of the ultrasonic wave generating means and the ultrasonic wave detecting means.
  10. A residual stress distribution measurement method for dividing a plate-shaped measurement target into a plurality of layers along a thickness direction thereof, and measuring a residual stress of each layer at a predetermined position on a surface of the measurement target,
    At a predetermined position (ultrasonic generation position) on the surface of the measurement object, a first step of generating an ultrasonic wave that proceeds obliquely with respect to the surface of the measurement object inside the measurement object;
    A second step of detecting the ultrasonic wave at a position (ultrasonic detection position) where the ultrasonic wave is reflected on the bottom surface of the measurement object and returns to the surface again,
    A third step of determining the distance between the ultrasonic wave generation position and the ultrasonic detection position for the ultrasonic wave,
    A fourth step of determining the propagation time during which the ultrasonic wave has propagated inside the measurement target based on the waveform data of the ultrasonic wave obtained by detecting the second step,
    For each of the longitudinal ultrasonic wave generated in the first step, the transverse ultrasonic wave displaced in the vertical width direction of the measurement object, and the transverse ultrasonic wave displaced in the horizontal width direction of the measurement object, The traveling direction is set in advance by the same number as the number of the layers, the ultrasonic waves are sequentially generated in the set traveling directions, and the first to fourth steps are repeated. For each ultrasonic wave, the distance between the ultrasonic wave generation position and the ultrasonic detection position for the ultrasonic wave generated in each of the traveling directions and the propagation time of the ultrasonic wave generated in each of the traveling directions. A fifth step for
    For each ultrasonic wave, based on the propagation time of the ultrasonic wave generated in each traveling direction and the distance between the ultrasonic wave generation position and the ultrasonic detection position for the ultrasonic wave generated in each traveling direction. A sixth step of calculating the sound speed of the ultrasonic wave in each of the layers,
    A seventh step of determining the internal temperature of each layer based on the sound speed of the one ultrasonic wave in each layer calculated in the sixth step,
    Eighth step of calculating the residual stress of each layer based on the sound speed of each ultrasonic wave in each layer and the internal temperature of each layer,
    A method for measuring a residual stress distribution, comprising:
  11. The residual stress distribution measuring method according to claim 10, wherein in the first step, an ultrasonic wave is generated using a probe, and in the second step, the ultrasonic wave is detected using a probe.
JP2003005518A 2002-06-17 2003-01-14 Residual stress distribution measuring apparatus and residual stress distribution measuring method Active JP4031711B2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2002175272 2002-06-17
JP2003005518A JP4031711B2 (en) 2002-06-17 2003-01-14 Residual stress distribution measuring apparatus and residual stress distribution measuring method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2003005518A JP4031711B2 (en) 2002-06-17 2003-01-14 Residual stress distribution measuring apparatus and residual stress distribution measuring method

Publications (2)

Publication Number Publication Date
JP2004077460A true JP2004077460A (en) 2004-03-11
JP4031711B2 JP4031711B2 (en) 2008-01-09

Family

ID=32032393

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2003005518A Active JP4031711B2 (en) 2002-06-17 2003-01-14 Residual stress distribution measuring apparatus and residual stress distribution measuring method

Country Status (1)

Country Link
JP (1) JP4031711B2 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011196953A (en) * 2010-03-23 2011-10-06 Nippon Steel Corp Residual stress calculating device, residual stress measuring device, method of calculating residual stress, method of measuring residual stress and program
US8181524B2 (en) 2008-12-26 2012-05-22 Panasonic Corporation Ultrasonic stress measurement method and device
CN104048785A (en) * 2014-06-09 2014-09-17 中国航空工业集团公司北京航空材料研究院 Method for nondestructive evaluation of residual stress levels in aluminum alloy forged piece through ultrasonic waves
CN104764803A (en) * 2014-12-25 2015-07-08 电子科技大学 Material stress detection technology based on changes of wavelength of supersonic waves

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8181524B2 (en) 2008-12-26 2012-05-22 Panasonic Corporation Ultrasonic stress measurement method and device
JP2011196953A (en) * 2010-03-23 2011-10-06 Nippon Steel Corp Residual stress calculating device, residual stress measuring device, method of calculating residual stress, method of measuring residual stress and program
CN104048785A (en) * 2014-06-09 2014-09-17 中国航空工业集团公司北京航空材料研究院 Method for nondestructive evaluation of residual stress levels in aluminum alloy forged piece through ultrasonic waves
CN104048785B (en) * 2014-06-09 2016-02-24 中国航空工业集团公司北京航空材料研究院 A kind of method of ultrasonic nonodestruction evaluation aluminum alloy forge piece internal residual stress level
CN104764803A (en) * 2014-12-25 2015-07-08 电子科技大学 Material stress detection technology based on changes of wavelength of supersonic waves

Also Published As

Publication number Publication date
JP4031711B2 (en) 2008-01-09

Similar Documents

Publication Publication Date Title
Busse Optoacoustic and photothermal material inspection techniques
Scruby Some applications of laser ultrasound
US5748318A (en) Optical stress generator and detector
US6400449B2 (en) Optical stress generator and detector
US4632561A (en) Evaluation of surface and subsurface characteristics of a sample
US6321601B1 (en) Optical method for the characterization of laterally-patterned samples in integrated circuits
US7353709B2 (en) Method and system for determining material properties using ultrasonic attenuation
Fromme et al. Measurement of the scattering of a Lamb wave by a through hole in a plate
Leong et al. Structural health monitoring using scanning laser vibrometry: III. Lamb waves for fatigue crack detection
US4046477A (en) Interferometric method and apparatus for sensing surface deformation of a workpiece subjected to acoustic energy
EP0129205A2 (en) Noncontacting ultrasonic flaw detecting method
Sohn et al. Interaction of a scanning laser-generated ultrasonic line source with a surface-breaking flaw
US7605924B2 (en) Laser-ultrasound inspection using infrared thermography
CA1325842C (en) Method and device for nondestructive evaluation
CN102323216B (en) Welding inspection method and apparatus thereof
JP2004515748A (en) System and method for detecting porosity of composites using ultrasound
US6057927A (en) Laser-ultrasound spectroscopy apparatus and method with detection of shear resonances for measuring anisotropy, thickness, and other properties
KR101134431B1 (en) Ultrasonic scanning device and method
JP4321190B2 (en) Material thickness measuring method and apparatus
US4541280A (en) Efficient laser generation of surface acoustic waves
JPH10505425A (en) Laser vibrometer for vibration measurement
EP0400770A2 (en) Measuring the strength of a material within a moving web
CA2348381A1 (en) Laser-ultrasonic measurement of elastic properties of a thin sheet and of tension applied thereon
JP3735650B2 (en) Surface inspection device
US5814730A (en) Material characteristic testing method and apparatus using interferometry to detect ultrasonic signals in a web

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20050914

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20070713

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20071012

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20071019

R151 Written notification of patent or utility model registration

Ref document number: 4031711

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R151

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20101026

Year of fee payment: 3

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20101026

Year of fee payment: 3

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20111026

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20111026

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20121026

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20121026

Year of fee payment: 5

S531 Written request for registration of change of domicile

Free format text: JAPANESE INTERMEDIATE CODE: R313531

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20131026

Year of fee payment: 6

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350

S533 Written request for registration of change of name

Free format text: JAPANESE INTERMEDIATE CODE: R313533

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20131026

Year of fee payment: 6

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20131026

Year of fee payment: 6

S533 Written request for registration of change of name

Free format text: JAPANESE INTERMEDIATE CODE: R313533

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350