MEASUREMENT SYSTEM AND MEASUREMENT METHOD

A measurement system according to an aspect of the present invention enables measurement of an intensity distribution of diffracted X-rays obtained by irradiating a fillet portion of a metallic structure with X-rays, the metallic structure comprising: an axis portion; and a flange portion protruding radially from the axis portion, wherein the metallic structure comprises the fillet portion in a connection portion between the axis portion and the flange portion, the measurement system including: a diffracted X-rays measurement device provided with an irradiation unit that irradiates the fillet portion with X-rays; and a positioning device that positions the diffracted X-rays measurement device with respect to the fillet portion, in which the positioning device including: a moving mechanism that moves three-dimensionally the diffracted X-rays measurement device relative to the fillet portion; and a rotation mechanism that rotates the diffracted X-rays measurement device in such a direction that an angle of incidence of the X-rays with respect to the fillet portion is changed.

TECHNICAL FIELD

The present invention relates to a measurement system and a measurement method.

BACKGROUND ART

Recently, a technique for measuring a residual stress using X-rays has been widely applied. In this technique, a lattice distortion occurring inside a specimen having a crystalline structure is measured using X-rays, and the measurement result is converted into a residual stress.

As a method for measuring a residual stress using X-rays, a cos α method is known. The cos α method includes: irradiating a specimen with X-rays at a specific angle of incidence; two-dimensionally detecting intensities of diffracted X-rays generated by reflection of the X-rays by the specimen; and measuring a residual stress based on a diffraction ring formed by an intensity distribution of the diffracted X-rays as detected.

Today, determining hardness and the like of a specimen through calculation of a half width of an X-ray diffraction intensity curve based on an intensity distribution of the diffracted X-rays is also practiced.

An X-ray stress measuring apparatus in which an X-ray emitter that emits X-rays, an imaging plate on which a diffraction ring due to diffracted X-rays is formed, and the like are disposed in a single housing (see Japanese Unexamined Patent Application, Publication No. 2012-225796) can be used as an X-ray stress measuring apparatus for measuring a residual stress of a fillet portion in a metal structure including: an axis portion having a cylindrical shape; and a flange portion (plate-shaped portion) protruding radially from the axis portion, wherein the fillet portion for alleviating stress concentration is provided in a connection portion between the axis portion and the flange portion.

PRIOR ART DOCUMENTS

Patent Documents

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

In the measurement of the residual stress by the cos α method, the angle of incidence is typically set to be greater than or equal to 15° and less than or equal to 65°. However, with regard to a metal structure including: an axis portion having a cylindrical shape; and a flange portion (plate-shaped portion) protruding radially from the axis portion, wherein a fillet portion for alleviating stress concentration is provided in a connection portion between the axis portion and the flange portion, for example in a case of irradiating a plurality of positions in the fillet portion with X-rays, there is a higher risk of interference between the flange portion or the axis portion and the X-ray stress measuring apparatus, leading to difficulty in arranging the X-ray stress measuring apparatus in a desired position.

The present invention was made in view of the foregoing circumstances, and an object of the present invention is to provide a measurement system and a measurement method that enable easy measurement of an intensity distribution of diffracted X-rays in a desired arrangement.

Means for Solving the Problems

A measurement system according to an aspect of the present invention enables measurement of an intensity distribution of diffracted X-rays obtained by irradiating a fillet portion of a metallic structure with X-rays, the metallic structure comprising: an axis portion; and a flange portion protruding radially from the axis portion, wherein the metallic structure comprises the fillet portion in a connection portion between the axis portion and the flange portion, the measurement system including: a diffracted X-rays measurement device provided with an irradiation unit that irradiates the fillet portion with X-rays; and a positioning device that positions the diffracted X-rays measurement device with respect to the fillet portion, in which the positioning device includes: a moving mechanism that moves three-dimensionally the diffracted X-rays measurement device relative to the fillet portion; and a rotation mechanism that rotates the diffracted X-rays measurement device in such a direction that an angle of incidence of the X-rays with respect to the fillet portion is changed.

The measurement system includes a positioning device that positions the diffracted X-rays measurement device with respect to the fillet portion, in which the positioning device includes: a moving mechanism that moves three-dimensionally the diffracted X-rays measurement device relative to the fillet portion; and a rotation mechanism that rotates the diffracted X-rays measurement device in such a direction that an angle of incidence of the X-rays with respect to the fillet portion is changed, whereby an intensity distribution of diffracted X-rays obtained by irradiating the fillet portion with X-rays can be easily measured in a desired arrangement.

It is preferred that the measurement system further includes a control unit that controls movement by the moving mechanism and rotation by the rotation mechanism such that the diffracted X-rays measurement device does not come into contact with the axis portion and the flange portion. The measurement system can measure the intensity distribution of the diffracted X-rays more easily in a desired arrangement due to further comprising a control unit that controls movement by the moving mechanism and rotation by the rotation mechanism such that the diffracted X-rays measurement device does not come in contact with the axis portion and the flange portion.

It is preferred that the control unit controls the movement by the moving mechanism and the rotation by the rotation mechanism within such a range that the diffracted X-rays measurement device can detect a peak of diffracted X-rays. Due to the control unit thus controlling the movement by the moving mechanism and the rotation by the rotation mechanism within such a range that the diffracted X-rays measurement device can detect a peak of diffracted X-rays, the intensity distribution of the diffracted X-rays can be measured easily and reliably.

In a case in which: an axis passing through a fillet center and being parallel to a central axis of the axis portion is represented by an X-axis; an axis passing through the fillet center and being parallel to a protrusion direction of the flange portion is represented by a Z-axis; a coordinate of the fillet center is represented by (0, 0); a coordinate of a rotation center of the diffracted X-rays measurement device is represented by (X, Z); an irradiation distance of the X-rays by the diffracted X-rays measurement device is denoted by L [mm]; a minimum value of the irradiation distance of the X-rays is denoted by Lmin[mm]; a maximum value of the irradiation distance of the X-rays is denoted by Lmax[mm]; a fillet angle is denoted by θ [°]; a fillet radius is denoted by R [mm]; an angle of incidence of the X-rays is denoted by Ψ[°]; a distance between an end portion of a housing of the diffracted X-rays measurement device on the fillet portion side and the rotation center in the irradiation direction of the X-rays is denoted by h [mm]; a top-to-bottom width of an end portion of the housing on a side adjacent to the fillet portion is denoted by W [mm]; a complementary angle of the Bragg angle is denoted by η [°]; a top-to-bottom width of a detection region of a two-dimensional detector of the diffracted X-rays measurement device is denoted by D [mm], and an interval between the flange portion and an imaginary straight line which passes through the fillet center and is parallel to the flange portion is denoted by a [mm], it is preferred that the following inequality 1 and inequality 2 are satisfied:

wherein with respect to an imaginary straight line which passes through a measurement site and the fillet center, the angle of incidence Ψ of the X-rays is defined to be positive in a case of tilting toward the axis portion, and is defined to be negative in a case of tilting toward the flange portion: in a case in which Ψ≥0, the irradiation distance L of the X-rays satisfies the following inequality 3; and in a case in which Ψ<0, the irradiation distance L of the X-rays satisfies the following inequality 4:

Due to positioning the diffracted X-rays measurement device within a range that satisfies the above inequalities1and2, the measurement system can easily inhibit contact of the axis portion and the flange portion with the diffracted X-rays measurement device.

It is preferred that the control unit controls the movement by the moving mechanism and the rotation by the rotation mechanism on basis of the following inequality 5 in a case in which Ψ≥0, and controls the movement by the moving mechanism and the rotation by the rotation mechanism on basis of the following inequality 6 in a case in which Ψ<0,

Due to the control unit thus controlling the movement by the moving mechanism and the rotation by the rotation mechanism on the basis of the above inequalities5and6, the intensity distribution of the diffracted X-rays can be measured easily and reliably, while contact of the axis portion and the flange portion with the diffracted X-rays measurement device is inhibited.

It is preferred that the moving mechanism includes: a first moving body that fits to an outer peripheral face of the axial portion and rotates in a circumferential direction relative to the axial portion; a perpendicular axis that is connected to the first moving body and extends in a direction orthogonal to the central axis of the axis portion; a second moving body that is connected to the perpendicular axis and movable in an axial direction of the perpendicular axis; and a slide mechanism that moves the first moving body or the perpendicular axis in an axial direction of the axis portion, in which the diffracted X-rays measurement device is connected to the second moving body. Due to the moving mechanism thus including: a first moving body that fits to an outer peripheral face of the axial portion and rotates in a circumferential direction relative to the axial portion; a perpendicular axis that is connected to the first moving body and extends in a direction orthogonal to the central axis of the axis portion; a second moving body that is connected to the perpendicular axis and movable in an axial direction of the perpendicular axis; and a slide mechanism that moves the first moving body or the perpendicular axis in an axial direction of the axis portion, in which the diffracted X-rays measurement device is connected to the second moving, the intensity distribution of the diffracted X-rays can be more easily measured in a desired arrangement.

It is preferred that the diffracted X-rays measurement device is configured to be able to calculate a residual stress of the fillet portion by the cos α method. The measurement system being able to easily measure the intensity distribution of the diffracted X-rays in a desired arrangement is suitable for calculating the residual stress of the fillet portion.

It is preferred that the diffracted X-rays measurement device is configured to be able to calculate a half width of an X-ray diffraction intensity curve. The measurement system being able to easily measure the intensity distribution of the diffracted X-rays in a desired arrangement is suitable for calculating the half width of the X-ray diffraction intensity curve.

A measurement method according to another aspect of the present invention enables measurement of an intensity distribution of diffracted X-rays obtained by irradiating a fillet portion of a metallic structure with X-rays, the metallic structure comprising: an axis portion; and a flange portion protruding radially from the axis portion, wherein the metallic structure comprises the fillet portion in a connection portion between the axis portion and the flange portion, the measurement method using a diffracted X-rays measurement device provided with an irradiation unit that irradiates the fillet portion with X-rays, and including: moving three-dimensionally the diffracted X-rays measurement device relative to the fillet portion; rotating the diffracted X-rays measurement device in such a direction that an angle of incidence of the X-rays with respect to the fillet portion is changed; and measuring the intensity distribution of diffracted X-rays by the diffracted X-rays measurement device.

Due to the measurement method including moving three-dimensionally the diffracted X-rays measurement device relative to the fillet portion; and rotating the diffracted X-rays measurement device in such a direction that an angle of incidence of the X-rays with respect to the fillet portion is changed, an intensity distribution of diffracted X-rays obtained by irradiating the fillet portion with X-rays can be easily measured in a desired arrangement.

It is preferred that, in the measurement, the residual stress of the fillet portion is calculated by the cos α method. The measurement method being able to easily measure the intensity distribution of the diffracted X-rays in a desired arrangement is suitable for calculating the residual stress of the fillet portion.

It is preferred that, in the measurement, a half width of an X-ray diffraction intensity curve is calculated. The measurement method being able to easily measure the intensity distribution of the diffracted X-rays in a desired arrangement is suitable for calculating the half width of the X-ray diffraction intensity curve.

It is preferred that: the fillet portion is continuously irradiated with X-rays in parallel with at least one of the moving and the rotating; and in the measurement, a single diffraction ring, which is given by overlapping a plurality of diffraction rings generated by diffraction of the X-rays, is determined. Due to the fillet portion thus being continuously irradiated with X-rays in parallel with at least one of the moving and the rotating, and a single diffraction ring, which is given by overlapping a plurality of diffraction rings generated by diffraction of the X-rays, being obtained in the measurement, easy and highly accurate calculation of the residual stress or the half width is enabled.

It is preferred that the measurement method includes, after the measuring, repeating: at least one of the moving and the rotating; and the measuring. Due to thus including, after the measuring, repeating: at least one of the moving and the rotating; and the measuring, more accurate calculation of the residual stress or the half width is enabled.

It is preferred that the measurement method further includes determining an average value of a plurality of calculated values obtained by the measuring. Due to thus further including determining an average value of a plurality of calculated values obtained by the measuring, easy and highly accurate measurement of the residual stress or the half width is enabled.

It is to be noted that according to the present invention, the “fillet center” as referred to herein means a center of curvature of the fillet portion. The “fillet angle” as referred to herein means an angle in a side view, formed between an imaginary straight line which passes through the fillet center and is orthogonal to the axis portion, and an imaginary straight line which passes through the measurement site and the fillet center (see θ inFIG.2). The “fillet radius” as referred to herein means a radius of curvature of the fillet portion. The “top-to-bottom width” as referred to herein means a width between a surface being on a side adjacent to the axis portion, and a surface opposed to this surface and being on a side adjacent to the flange portion. The “interval between the flange portion and the imaginary straight line which passes through the fillet center and is parallel to the flange portion” as referred to herein means an average value of intervals at 5 arbitrary points between the imaginary straight line and the flange portion (excluding the fillet portion).

Effects of the Invention

As described above, the measurement system according to an aspect of the present invention and the measurement method according to another aspect of the present invention enable easy measurement of the intensity distribution of the diffracted X-rays in a desired arrangement.

DESCRIPTION OF EMBODIMENTS

Measurement System

As illustrated inFIGS.1and2, a measurement system1measures an intensity distribution of diffracted X-rays obtained by irradiating with X-rays a fillet portion4of a metallic structure M, the metallic structure M including: an axis portion2; and a flange portion3protruding radially from the axis portion2, in which the metallic structure M includes the fillet portion4in a connection portion between the axis portion2and the flange portion3. The flange portion3protrudes in a direction perpendicular to a central axis of the axis portion2. As illustrated inFIG.2, the measurement system1includes a diffracted X-rays measurement device10provided with an irradiation unit11that irradiates the fillet portion4with X-rays. The diffracted X-rays measurement device10is exemplified by an X-ray stress measuring apparatus. In addition, as shown inFIG.1andFIG.3, the measurement system1includes a positioning device20that positions the diffracted X-rays measurement device10with respect to the fillet portion4. Furthermore, as shown inFIG.1andFIG.3, the measurement system1includes a control unit30that controls operation of the diffracted X-rays measurement device10by the positioning device20such that the diffracted X-rays measurement device10does not come into contact with the axis portion2and the flange portion3.

As shown inFIG.2, the diffracted X-rays measurement device10includes an irradiation unit11which delivers X-rays; a two-dimensional detector12which detects a diffraction ring generated by Bragg diffraction of the X-rays delivered from the irradiation unit11to the fillet portion4(more specifically, a measurement site S in the fillet portion4); and a housing13in which the irradiation unit11and the two-dimensional detector12are mounted. The diffracted X-rays measurement device10is configured to be able to calculate a residual stress of the fillet portion4by the cos α method. Specifically, the diffracted X-rays measurement device10is configured to be able to irradiate the measurement site S with X-rays, to detect intensity of diffracted X-rays generated by reflection of the X-rays by the two-dimensional detector12, and to calculate a residual stress on the basis of a diffraction ring formed by an intensity distribution of the diffracted X-rays which have been detected. In addition, the diffracted X-rays measurement device10is configured to be able to calculate a half width of an X-ray diffraction intensity curve based on the intensity distribution of the diffracted X-rays. The “half width of an X-ray diffraction intensity curve” as referred to means a width of a profile at an intensity value of half the peak of the X-ray diffraction intensity curve. The half width is reported to vary to reflect non-uniform strain caused by quenching, tempering, plastic deformation, and the like, and considered to be in correlation to, for example, hardness, plastic strain, and the like of the fillet portion4. The half width may also be, for example, a value calculated for an arbitrary X-ray diffraction intensity curve constituting the diffraction ring, an average value of values calculated for a plurality of X-ray diffraction intensity curves constituting the diffraction ring, and the like.

The two-dimensional detector12is provided at an end on an X-ray emission side of the housing13. That is to say, the two-dimensional detector12is provided at an end on a side facing a measurement site S. The two-dimensional detector12is exemplified by an imaging plate. The housing13has, for example, a substantially rectangular parallelepiped shape. The housing13has: the lower surface13aadjacent to the axis portion2; and the upper surface13bfacing the lower surface13aand being adjacent to the flange portion3. The irradiation unit11and the two-dimensional detector12are integrally provided through being arranged in the housing13. A calculator14capable of using the diffraction ring to calculate the residual stress by the cos α method is connected to the housing13. In addition, the calculator14is configured to be able to calculate a half width of an X-ray diffraction intensity curve based on the intensity distribution of the diffracted X-rays.

Positioning Device

As shown inFIG.3, the positioning device20includes: a moving mechanism21that moves three-dimensionally the diffracted X-rays measurement device10relative to the fillet portion4; and a rotation mechanism22that rotates the diffracted X-rays measurement device10in such a direction that an angle of incidence Ψ (seeFIG.2) of the X-rays with respect to the fillet portion4is changed. The moving mechanism21is connected to the axis portion2or the flange portion3. The moving mechanism21is connected to the axis portion2in the present embodiment.

Moving Mechanism

The moving mechanism21includes: a first moving body23that fits to an outer peripheral face of the axial portion2and rotates in a circumferential direction relative to the axial portion2; a perpendicular axis24that is connected to the first moving body23and extends in a direction orthogonal to the central axis of the axis portion2; a second moving body25that is connected to the perpendicular axis24and movable in an axial direction of the perpendicular axis24; and a slide mechanism26that moves the perpendicular axis24in an axial direction of the axis portion2. the diffracted X-rays measurement device10is connected to the second moving body25.

As shown inFIG.3, the first moving body23includes: a frame23athat fits to the outer peripheral face of the axial portion2; a plurality of rollers23cof which rotational axes23bare arranged in parallel to the central axis of the axis portion2and that are in contact with the outer peripheral face of the axial portion2; and a motor23dthat rotationally drives the plurality of rollers23c. The first moving body23rotationally drives the plurality of rollers23cby the motor23dto rotate the diffracted X-rays measurement device10in a circumferential direction relative to the axis portion2. The first moving body23may also rotate the axis portion2in a circumferential direction to rotate the diffracted X-rays measurement device10in a circumferential direction relative to the axis portion2. Alternatively, in the measurement system1, the first moving body23may rotate in the circumferential direction of the axis portion2to rotate the diffracted X-rays measurement device10in the circumferential direction relative to the axis portion2.

The perpendicular axis24may be either directly connected to the first moving body23, or connected to the first moving body23via another member. In the present embodiment, the perpendicular axis24is connected to the first moving body23via the slide mechanism26.

The second moving body25is configured to fit to the perpendicular axis24and to be movable in the axial direction of the perpendicular axis24by a motor (not shown in the figure). The second moving body25is, for example, in a frame-like shape externally fitting to the perpendicular axis24.

The slide mechanism26includes a supporting portion26athat supports the perpendicular axis24in a slidable manner in the axial direction of the axis portion2, and a motor (not shown in the figure) that drives the perpendicular axis24in the axial direction of the axis portion2.

In the measurement system1, due to the moving mechanism21including the first moving body23, the perpendicular axis24, the second moving body25, and the slide mechanism26, and the diffracted X-rays measurement device10being connected to the second moving body25, the moving mechanism21is less likely to be hindered from arranging the diffracted X-rays measurement device10in a desired position. In other words, in a case of measuring the residual stress and the like of the fillet portion4by the diffracted X-rays measurement device10, irradiation of the fillet portion4with X-rays in a desired arrangement may be difficult due to interference between the diffracted X-rays measurement device10or the positioning device20, and the axis portion2or the flange portion3. In this regard, due to the moving mechanism21having the above-described configuration, the measurement system1enables easy and reliable measurement of the residual stress and the like of the fillet portion4in a desired arrangement, while inhibiting interference between the diffracted X-rays measurement device10or the positioning device20, and the axis portion2or the flange portion3.

Rotation Mechanism

The rotation mechanism22includes: a connecting body22athat connects the second moving body25and the diffracted X-rays measurement device10; and a motor (not shown in the figure) that rotationally drives the connecting body22aaround an axis perpendicular to the central axis of the axis portion2. The diffracted X-rays measurement device10is directly connected to the connecting body22a, and connected to the second moving body25via the connecting body22a.

Control Unit

The control unit30is configured to include, for example, a computer with: a CPU (Central Processing Unit) that carries out data processing; and a storage unit such as semiconductor memory that stores various types of data transitorily or permanently. The control unit30controls movement by the moving mechanism21and rotation by the rotation mechanism22such that the diffracted X-rays measurement device10does not come in contact with the axis portion2and the flange portion3. Due to including the control unit30, the measurement system1can easily measure the residual stress and the like of the fillet portion4in a desired arrangement.

The control unit30controls the movement by the moving mechanism21and the rotation by the rotation mechanism22within such a range that the diffracted X-rays measurement device10(more specifically, the two-dimensional detector12) can detect a peak of diffracted X-rays. According to this configuration, the residual stress and the like of the fillet portion4can be measured easily and reliably.

A control procedure by the control unit30is described with reference toFIG.2. The control unit30controls arrangement of the housing13by using a two-dimensional Cartesian coordinate system in which a coordinate of the fillet center P is represented by (0, 0), an axis passing through the fillet center P and being parallel to the central axis of the axis portion2is represented by an X-axis, and an axis passing through the fillet center P and being parallel to a protruding direction of the flange portion3is represented by a Z-axis.

The control unit30controls the arrangement of the diffracted X-rays measurement device10such that, in a case in which: a coordinate of a rotation center Q of the diffracted X-rays measurement device10is represented by (X, Z); an irradiation distance of the X-rays by the diffracted X-rays measurement device10is denoted by L [mm]; a minimum value of the irradiation distance L of the X-rays is denoted by Lmin[mm]; a maximum value of the irradiation distance L of the X-rays is denoted by Lmax[mm]; a fillet angle is denoted by θ [°]; a fillet radius is denoted by R [mm]; an angle of incidence of X-rays (an angle formed by an imaginary straight line N that passes through the measurement site S and the fillet center P; and the X-rays) is denoted by Ψ [°]; a distance between an end portion of the housing13on the fillet portion4side and the rotation center Q in the irradiation direction of the X-rays is denoted by h [mm]; a top-to-bottom width of an end portion of the housing13on a side adjacent to the fillet portion4(width between the lower surface13aand the upper surface13b) is denoted by W [mm]; a complementary angle of the Bragg angle is denoted by η [°]; a top-to-bottom width of the two-dimensional detector12is denoted by D [mm]; and an interval between the flange portion3and an imaginary straight line which passes through the fillet center P and is parallel to the flange portion3is denoted by a [mm], the following inequality 1 and inequality 2 are satisfied.

With respect to the imaginary straight line N which passes through the measurement site S and the fillet center P, the angle of incidence Ψ of the X-rays is defined to be positive in a case of tilting toward the axis portion2, and is defined to be negative in a case of tilting toward the flange portion3: in a case in which Ψ≥0, the irradiation distance L of the X-rays satisfies the following inequality 3; and in a case in which Ψ<0, the irradiation distance L of the X-rays satisfies the following inequality 4.

Due to positioning the diffracted X-rays measurement device10within a range that satisfies the above formulae 1 and 2, the measurement system1can easily inhibit contact of the axis portion2and the flange portion3with the diffracted X-rays measurement device10.

It is preferred that, in a case in which Ψ≥0, the control unit30controls movement by the moving mechanism21and rotation by the rotation mechanism22on the basis of the following inequality 5.

Meanwhile, it is preferred that, in a case in which Ψ<0, the control unit30controls movement by the moving mechanism21and rotation by the rotation mechanism22on the basis of the following inequality 6.

Due to thus controlling the movement by the moving mechanism21and the rotation by the rotation mechanism22on the basis of the above formulae 5 and 6, the measurement system1can measure the residual stress and the like of the fillet portion4easily and reliably, while contact of the axis portion2and the flange portion3with the diffracted X-rays measurement device10is inhibited.

FIG.4shows a relationship between the angle of incidence Ψ of the X-rays and the measurement error in the residual stress. As shown inFIG.4, when the absolute value of the angle of incidence Ψ of the X-rays is smaller, an impact of a configuration error in the angle of incidence of the X-rays is greater. Particularly when the absolute value of the angle of incidence Ψ of the X-rays is less than 10°, an impact of the configuration error in the angle of incidence of the X-rays is remarkable. Therefore, it is preferred that the control unit30controls the arrangement of the housing13such that the absolute value of the angle of incidence Ψ of the X-rays is at least 10°, and preferably at least 20°.

In the measurement system1, due to the control unit30that controls the movement mechanism21and the rotation mechanism22, the housing13can be easily arranged so as to increase the absolute value of the angle of incidence Ψ of the X-rays. In other words, in a case of arranging the housing13manually, it is not easy to find an arrangement in which the absolute value of the angle of incidence Ψ of the X-rays is great in such a range that the housing13does not come into contact with the axis portion2and the flange portion3. On the other hand, in the measurement system1, due to the control unit30that controls the movement mechanism21and the rotation mechanism22, the desired arrangement of the housing13can be automatically found, and the housing13can be moved and rotated to be in this arrangement.

It is preferred that, with respect to the fillet angle θ of the fillet portion4, the control unit30derives such an irradiation distance L of the X-rays and such an angle of incidence Ψ of the X-rays that the diffracted X-rays measurement device10does not come into contact with the axis portion2and the flange portion3. Specifically, the control unit30accepts, with respect to the particular fillet angle θ, inputs of the irradiation distance L of the X-rays and the angle of incidence Ψ of the X-rays desired by a user. When the irradiation distance L of the X-rays and the angle of incidence Ψ of the X-rays are input, the control unit30determines whether it is possible to arrange the housing13with the irradiation distance L of the X-rays and the angle of incidence Ψ of the X-rays being input by the user, on the basis of the above inequality 5 or 6. In a case in which it is possible to arrange the housing13with the irradiation distance L of the X-rays and the angle of incidence Ψ of the X-rays being input by the user, the control unit30moves and rotates the housing13in the arrangement corresponding to the input values, or notifies the user that the arrangement of the housing13is possible. According to this configuration, the residual stress and the like of the fillet portion4can be measured more easily in the desired arrangement.

It is preferred that the control unit30derives the irradiation distance L of the X-rays and the angle of incidence Ψ of the X-rays with which arrangement of the housing13is possible, for a plurality of fillet angles θ. In the measurement system1, due to the control unit30that controls the movement mechanism21and the rotation mechanism22, the residual stress of the fillet portion4can be calculated for a plurality of times in a desired arrangement and in a short period of time.

Note that, in a case of calculating the half width of the X-ray diffraction intensity curve, the diffracted X-rays measurement device10is not required to be arranged to increase the absolute value of the angle of incidence Ψ of the X-rays. For example, in a case of calculating the half width of the X-ray diffraction intensity curve, the angle of incidence Ψ of the X-rays may be 0°. However, in the measurement system1, an arrangement of the diffracted X-rays measurement device10suited for calculating the residual stress of the fillet portion4facilitates calculation of both the residual stress of the fillet portion4and the half width of the X-ray diffraction intensity curve.

It is preferred that the control unit30controls the movement by the moving mechanism21and the rotation by the rotation mechanism22such that the diffracted X-rays measurement device10is rotated in the circumferential direction of the axis portion2, or moved in a particular plane including the central axis of the axis portion2.

The diffracted X-rays measurement device10may either deliver the X-rays continuously in parallel to positioning by the positioning device20, or deliver the X-rays after positioning in a particular arrangement by the positioning device20. Specific examples of the diffracted X-rays measurement device10delivering the X-rays continuously in parallel to positioning by the positioning device20include a configuration of delivering the X-rays while the diffracted X-rays measurement device10is relatively rotated in the circumferential direction of the axis portion2. According to this configuration, the residual stress and the like of the fillet portion4can be measured easily and with high accuracy.

In a case in which the diffracted X-rays measurement device10has calculated the residual stress of the fillet portion4for a plurality of times, it is preferred that the diffracted X-rays measurement device10determines an average value of a plurality of calculated values (calculated values of the residual stress) by the calculator14. Alternatively, in a case in which the diffracted X-rays measurement device10has calculated the half width of the X-ray diffraction intensity curve for a plurality of times, it is preferred that the diffracted X-rays measurement device10determines an average value of a plurality of calculated values (calculated values of the half width) by the calculator14. Due to determining the average value of the plurality of calculated values by the calculator14, the measurement system1can reduce the measurement error in the residual stress or the half width.

FIG.5shows a relationship between the irradiation area of the X-rays and the measurement error in the residual stress. InFIG.5, a collimated diameter of letting through the X-rays is 1 mm, and an irradiation area of one point is about 6.5 mm2. As shown inFIG.5, increasing a total value of the irradiation area enables reduction in the measurement error in the residual stress. Particularly, the total value of the irradiation area being at least 25 mm2enables sufficient reduction in the measurement error in the residual stress. A method for increasing the total value of the irradiation area of the X-rays is exemplified by a method of delivering the X-rays for a plurality of times while arbitrarily changing the arrangement of the housing13, a method of delivering the X-rays while swinging the housing13in the circumferential direction of the axis portion2, a method of delivering the X-rays at a plurality of angles of incidence Ψ, and the like. Note that inFIG.5, with regard to a segregation portion of a bainitic structure, a portion with no segregation of the bainitic structure, and a martensite structure, the X-rays are delivered for a plurality of times such that the respective total values of the irradiation areas are great.

Measuring Method

Next, the measurement method according to an embodiment of the present invention is described. The measurement method measures an intensity distribution of diffracted X-rays obtained by irradiating with X-rays a fillet portion4of a metallic structure M, the metallic structure M including: an axis portion2; and a flange portion3protruding radially from the axis portion2, in which the metallic structure M includes the fillet portion4in a connection portion between the axis portion2and the flange portion3. The measurement method can be carried out by using the measurement system1illustrated inFIG.1. Therefore, the measurement method using the measurement system1is described hereinafter.

The measurement method includes a step (moving step) of moving three-dimensionally the diffracted X-rays measurement device10relative to the fillet portion4; a step (rotating step) of rotating the diffracted X-rays measurement device10in such a direction that an angle of incidence Ψ of the X-rays with respect to the fillet portion4is changed; and a step (measuring step) of measuring the intensity distribution of diffracted X-rays by the diffracted X-rays measurement device10. The measurement method may include, after the measuring step, a step (repeating step) of repeating: at least one of the moving step and the rotating step; and the measuring step. The measurement method may also include a step (average value calculating step) of determining an average value of a plurality of calculated values determined by the measuring step (a plurality of calculated values of the residual stress or a plurality of calculated values of the half width).

Moving Step

In the moving step, the housing13is moved to a desired position by the control unit30that controls the moving mechanism21.

Rotating Step

In the rotating step, the housing13is rotated to a desired angle by the control unit30rotating the rotation mechanism22. Note that the moving step and the rotating step may take place either one after another or simultaneously.

Measuring Step

In the measuring step, the residual stress of the fillet portion4is calculated by the cos α method. Specifically, in the measuring step, the residual stress is calculated on the basis of a diffraction ring generated by Bragg diffraction of the X-rays delivered from the diffracted X-rays measurement device10to the fillet portion4(more specifically, the measurement site S). In addition, in the measuring step, the half width of the X-ray diffraction intensity curve based on the intensity distribution of the diffracted X-rays is calculated.

The measuring step may be configured to, for example, irradiate the fillet portion4with X-rays in the arrangement after the moving step and the rotating step, detect by the two-dimensional detector12the diffraction ring generated by Bragg diffraction of the X-rays delivered, and calculate the residual stress by the calculator14using the cos α method. Alternatively, the measuring step may be configured to irradiate the fillet portion4with X-rays in the arrangement after the moving step and the rotating step, and calculate the half width of the X-ray diffraction intensity curve.

Yet alternatively, the measuring step may be configured to continuously irradiate the fillet portion with X-rays in parallel with at least one of the moving step and the rotating step, and obtain a single diffraction ring, which is given by overlapping a plurality of diffraction rings generated by diffraction of the X-rays. In this case, in the measuring step, the residual stress may be calculated on the basis of the single diffraction ring thus obtained. More specifically, it may be configured that the diffracted X-rays measurement device10constantly delivers X-rays to a continuously connected portion of the fillet portion4in parallel to at least one of the moving step and the rotating step, the two-dimensional detector12detects a single diffraction ring, which is given by overlapping a plurality of diffraction rings generated by diffraction of each of the X-rays at the fillet portion4, and the residual stress is calculated on the basis of the single diffraction ring in the measuring step. A configuration of continuously delivering X-rays to the fillet portion4in parallel to at least one of the moving step and the rotating step is exemplified by a method of continuously delivering X-rays to the fillet portion4while relatively rotating the diffracted X-rays measurement device10in the circumferential direction of the axis portion2. Due to calculating the residual stress on the basis of the single diffraction ring in the measuring step, the measurement method enables easily measuring, with high accuracy, the residual stress of the fillet portion4. Alternatively, the measuring method may be configured to calculate the half width on the basis of the single diffraction ring (in other words, on the basis of the X-ray diffraction intensity curve obtained by continuously delivering X-rays to the fillet portion4in parallel to at least one of the moving step and the rotating step). Note that, in a case of calculating the residual stress and the like on the basis of the single diffraction ring in the measuring step, the measurement method is not required to include the repeating step and the average value calculating step described later.

Repeating Step

In the repeating step, the arrangement of the housing13with respect to the fillet portion4is changed by carrying out at least one of the moving step and the rotating step after the measuring step. In the repeating step, the residual stress of the fillet portion4is calculated by delivering the X-rays from the diffracted X-rays measurement device10in the arrangement thus changed. Since the residual stress of the fillet portion4is typically distributed in a certain manner, carrying out the repeating step facilitates comprehension of the distribution of the residual stress. In addition, in the repeating step, the half width of the X-ray diffraction intensity curve is calculated by delivering X-rays from the diffracted X-rays measurement device10in the changed arrangement. Since the half width of the X-ray diffraction intensity curve may vary depending on the irradiation position of the X-rays, the repeating step facilitates more accurate comprehension of the half width.

The number of repetitions by the repeating step is arbitrary, and may be one. However, as shown inFIG.5, in light of sufficiently reducing the measurement error in the residual stress, the repeating step is preferably carried out repeatedly until the total value of the irradiation area of the X-rays is at least 25 mm2. In the repeating step, the residual stress may be calculated at a plurality of angles of incidence Ψ while changing the angle of incidence Ψ of the X-rays with respect to one measurement site S. For example, in the repeating step, the residual stress may be calculated at a plurality of angles of incidence Ψ while changing the angle of incidence Ψ of the X-rays by 10°.

Average Value Calculating Step

In the average value calculating step, an average value of values calculated by the measuring step carried out for a plurality of times including those of the repeating step. In the measurement method, the average value (average value of the residual stress) is calculated as the residual stress of the fillet portion4. In addition, in the measurement method, the average value (average value of the half width) is calculated as the half width of the X-ray diffraction intensity curve. Due to including the average value calculating step, the measurement method enables easy measurement of the residual stress and the half width with reduced measurement errors.

Advantages

The measurement system1includes the positioning device20that positions the diffracted X-rays measurement device10with respect to the fillet portion4, the positioning device20including: the moving mechanism21that moves three-dimensionally the diffracted X-rays measurement device10relative to the fillet portion4; and the rotation mechanism22that rotates the diffracted X-rays measurement device10in such a direction that the angle of incidence Ψ of the X-rays with respect to the fillet portion4is changed, whereby an intensity distribution of diffracted X-rays obtained by irradiating the fillet portion4with X-rays can be easily measured in a desired arrangement.

The measurement system1being able to easily measure the intensity distribution of the diffracted X-rays in a desired arrangement is suited for calculating the residual stress of the fillet portion4. In other words, the fillet portion4typically has a distribution of the residual stress in a direction of change of the angle of incidence Ψ of the X-rays, the circumferential direction of the axis portion2, and the like. The measurement system1enables positioning of the diffracted X-rays measurement device10with high accuracy in a short period of time, thus facilitating measurement of the residual stress in a plurality of positions in the fillet portion4. As a result, the distribution of the residual stress of the fillet portion4can be easily comprehended.

In addition, the measurement system1being able to easily measure the intensity distribution of the diffracted X-rays in a desired arrangement is suited for calculating the half width of the X-ray diffraction intensity curve.

Due to the measurement method including a step of moving three-dimensionally the diffracted X-rays measurement device10relative to the fillet portion4; and a step of rotating the diffracted X-rays measurement device10in such a direction that an angle of incidence Ψ of the X-rays with respect to the fillet portion4is changed, an intensity distribution of diffracted X-rays obtained by irradiating the fillet portion4with X-rays can be easily measured in a desired arrangement.

The measurement method being able to easily measure the intensity distribution of the diffracted X-rays in a desired arrangement is suited for calculating the residual stress of the fillet portion4. In addition, the measurement method being able to easily measure the intensity distribution of the diffracted X-rays in a desired arrangement is suited for calculating the half width of the X-ray diffraction intensity curve.

Other Embodiments

The above-described embodiments do not limit the configuration of the present invention. Therefore, in the above-described embodiments, the components of each part of the above-described embodiments can be omitted, replaced, or added based on the description in the present specification and general technical knowledge, and such omission, replacement, or addition should be construed as falling within the scope of the present invention.

The configuration of the positioning device is not limited to the configuration of the above-described embodiments. For example, in the positioning device, the moving mechanism may be connected to the flange portion. With reference toFIG.6, an example of the configuration in which the moving mechanism is connected to the flange portion is described. In the positioning device40illustrated inFIG.6, a moving mechanism41is connected to an upper face of the flange portion3. The moving mechanism41includes: a support base41athat is arranged on the upper face of the flange portion3; a first supporting rod41bthat protrudes upward from the support base41aand is rotatable in a circumferential direction; a second supporting rod41cthat is connected to the first supporting rod41band extends in a direction orthogonal to the first supporting rod41b; a moving body41dthat is connected to the second supporting rod41cand movable in an axial direction of the second supporting rod41c; and a third supporting rod41ethat is connected to the moving body41d, arranged in parallel to the first supporting rod41b, and movable in a top-to-bottom direction. The diffracted X-rays measurement device10is connected to a lower portion of the third supporting rod41evia the rotation mechanism42. In the configuration ofFIG.6as well, the measurement system enables measurement of the residual stress and the like of the fillet portion4in a desired arrangement.

In the above-described embodiments, the configuration in which the slide mechanism moves the perpendicular axis in the axial direction of the axis portion has been described. However, the measurement system may also be configured such that the slide mechanism moves the first moving body in the axial direction of the axis portion.

The measurement system may also be configured not to include the above-described control unit. For example, the measurement system may also be configured to arrange the diffracted X-rays measurement device in a desired position by means of the moving mechanism and the rotation mechanism operated by a user. In addition, even in a case in which the measurement system includes the control unit, the specific control procedure by the control unit is not limited to the configuration of the above-described embodiments. For example, the control unit may control the moving mechanism and the rotation mechanism to arrange the diffracted X-rays measurement device such that the angle of incidence Ψ of the X-rays approaches ±35° with respect to a particular fillet angle.

The measurement system and the measurement method may also be configured to enable calculation of only one of the residual stress of the fillet portion and the half width of the X-ray diffraction intensity curve. Alternatively, the measurement system and the measurement method may also be configured to calculate a value other than the residual stress of the fillet portion and the half width of the X-ray diffraction intensity curve.

As described above, in light of reducing the measurement error, it is preferred that the measurement method calculates the residual stress and the like of the fillet portion in a plurality of arrangements. However, in a case in which the absolute value of the angle of incidence Ψ of the X-rays can be sufficiently increased or the like, the measurement method may determine the residual stress and the like of the fillet portion from a value of only one desired point. In such a case, the measurement method is not required to include the repeating step and the average value calculating step described above.

Examples

Hereinafter, the present invention is described in detail by way of Examples, but the present invention should not be construed as being limited to description in the Examples.

By the measurement system1ofFIG.1, the residual stress of the fillet portion4of the metallic structure M including the axis portion2and the flange portion3protruding radially from the axis portion2was measured by the cos α method. As the diffracted X-rays measurement device10, an X-ray stress measuring apparatus was used in which a top-to-bottom width D of the detection region of the two-dimensional detector12was 70 mm, and a top-to-bottom width of the housing13was 102 mm. The fillet radius R of the fillet portion4was 29 mm, the complementary angle η of the Bragg angle was 23.6°, and the interval a between the flange portion3and the imaginary straight line which passes through the fillet center P and is parallel to the flange portion3was 8 mm.

FIG.7shows measurement results of the residual stress using the measurement system1. InFIG.7, with respect to a plurality of fillet angles θ, the control unit30derives such an irradiation distance L of the X-rays and such an angle of incidence Ψ of the X-rays that the diffracted X-rays measurement device10does not come into contact with the axis portion2and the flange portion3, and the residual stress of the fillet portion4is measured in the arrangement thus derived. As shown inFIG.7, due to using the measurement system1, the residual stress can be automatically measured for a plurality of fillet angles θ.

FIG.8shows a relationship between the number of measured points and the measuring time in a case of using the measurement system1(Example) and in a case of arranging the housing manually without using the measurement system1(Comparative Example). As shown inFIG.8, when the number of measured points is greater, using the measurement system1enables greater reduction of the measuring time.

In addition,FIG.9shows the half width calculated from the X-ray diffraction intensity curve obtained with the arrangement derived by the measurement inFIG.7. InFIG.9, an error bar indicates a range between the maximum value and the minimum value of the half width of the X-ray diffraction intensity curve constituting the diffraction ring, and each dot indicates an average value of the half width.FIG.9indicates that the measurement system1enables calculation of the half width of the X-ray diffraction intensity curve.

INDUSTRIAL APPLICABILITY

As described above, the measurement system according to the one aspect of the present invention is suited for measuring the residual stress and the like of the fillet portion.

EXPLANATION OF THE REFERENCE SYMBOLS

1Measurement system2Axis portion3Flange portion4Fillet portion10Diffracted X-rays measurement device11Irradiation unit12Two-dimensional detector13Housing13aLower surface13bUpper surface14Calculator20,40Positioning device21,41Moving mechanism22,42Rotation mechanism22aConnecting body23First moving body23aFrame23bRotational axis23cRoller23dMotor24Perpendicular axis25Second moving body26Slide mechanism26aSupporting portion30Control unit41aSupporting base41bFirst supporting rod41cSecond supporting rod41dMoving body41eThird supporting roda Interval between flange portion and imaginary straight line which passes through fillet center and is parallel to flange portionD Top-to-bottom width of detection region of two-dimensional detectorh Distance between end portion of housing on fillet portion side and rotation center in irradiation direction of X-raysL Irradiation distance of X-raysM Metallic structureN Imaginary straight line which passes through measurement site and fillet centerP Fillet centerQ Rotation center of diffracted X-rays measurement deviceR Fillet radiusS Measurement siteW Top-to-bottom width of end portion of housing on side adjacent to fillet portionθ Fillet angleΨ Angle of incidence of X-raysη Complementary angle of Bragg angle