JP6607127B2 - X-ray residual stress measurement method and X-ray residual stress measurement system - Google Patents

Description

  The present invention relates to an X-ray residual stress measurement method and an X-ray residual stress measurement system, and more particularly, an object to be measured from the shape of a diffraction ring formed by diffracting X-rays by irradiating the object to be measured with X-rays. The present invention relates to an X-ray residual stress measurement method and an X-ray residual stress measurement system for measuring the stress of a wire.

  2. Description of the Related Art Conventionally, a method is known in which a measurement object is irradiated with X-rays, the shape of a diffraction ring formed by diffracted X-rays is measured, and the stress of the measurement object is measured using the cos α method. (Patent Documents 1 and 2).

  In patent document 1, the incident angle of the X-ray with respect to the measuring object is detected from the intensity distribution of the diffraction ring generated when the X-ray is irradiated. In Patent Document 2, in order to minimize the missing diffraction ring generated when X-rays are irradiated on an object having a complicated shape, X-rays that are not obstructed by a part of the measurement object by measuring the shape with a laser. Finding the irradiation direction.

Japanese Patent Laying-Open No. 2015-145862 JP 2014-238295 A

  The cosα method has the advantage that the residual stress can be evaluated with a single incident X-ray, and the device can be downsized and evaluated for a short time. The influence of angular deviation and absorption due to the material varies greatly even in the measurement region, and this significantly reduces the accuracy.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an X-ray capable of accurately calculating the stress of a measurement object even when there is unevenness on the surface of the measurement object. To provide a residual stress measurement method and an X-ray residual stress measurement system.

  In order to achieve the above object, the X-ray residual stress measurement method according to the present invention is approximated by a shape measuring step for measuring a concavo-convex shape along a predetermined direction on the surface of a measurement object and a straight line of the measured concavo-convex shape. A region determining step for determining a region determined by a portion to be determined, a beam diameter selecting step for selecting a beam diameter of X-rays so that only the determined region is irradiated with X-rays, and a reference plane of the determined region An angle determining step for determining an angle between the X-ray and the selected X-ray beam diameter, and irradiating the determined region with X-rays and diffracting from the determined region; A diffraction ring measurement step for measuring the shape of the diffraction ring, a diffraction ring evaluation step for evaluating deformation of the measured diffraction ring shape from a reference shape, and an angle formed by the determined reference plane The response of the determined area The method comprising the stress calculation step of calculating a.

  Further, the X-ray residual stress measurement system according to the present invention is diffracted by irradiating the surface of the measurement object with X-rays by measuring a concavo-convex shape along a predetermined direction on the surface of the measurement object. An X-ray diffraction measurement device that measures the shape of a diffraction ring formed by X-rays, and a region that determines a region determined by a portion approximated to a straight line of a measured uneven shape based on a measurement result by the shape measurement device A determination unit; an angle determination unit that determines an angle between the determined region and a reference plane; and a beam diameter selection unit that selects an X-ray beam diameter so that only the determined region is irradiated with X-rays And the shape of the diffraction ring based on the shape of the diffraction ring measured by irradiating the determined area with the selected X-ray beam diameter by the X-ray diffraction measurement device. Evaluate deformation from reference shape And a computer including a stress calculation unit that calculates stress of the determined region from deformation of the evaluated diffraction ring based on an angle formed with the determined reference plane. It consists of

  According to the present invention, the surface shape of the object to be measured is measured to determine the region determined by the portion approximated to the measured straight line of the concavo-convex shape, and the angle formed with the reference plane is determined and determined. A diffraction ring formed by X-rays diffracted when the X-ray beam diameter is selected so that only the region is irradiated with X-rays, and the region determined with the selected beam diameter is irradiated with X-rays And measuring the stress of the determined region based on the deformation of the measured diffraction ring from the reference shape and the angle formed with the determined reference surface, and thereby measuring the surface of the object to be measured. Even if there is unevenness, there is an effect that the stress of the measurement object can be calculated with high accuracy.

(A) The figure which shows the diffraction line of one cross section of a diffraction ring when a measurement object has no unevenness, (B) The figure which shows the diffraction line of one cross section of a diffraction ring when a measurement object has unevenness, and ( C) It is a figure for demonstrating an apparent peak shift. It is a figure which shows an example of the X-ray residual stress measurement system which concerns on this Embodiment. It is a figure which shows an example of the three-dimensional shape measuring apparatus which concerns on this Embodiment. It is a figure which shows the laser irradiation point on the surface of a measuring object. It is a figure which shows the state which moved the imaging plate to the reading start position in a diffraction ring reading area. It is a block diagram which shows the structure of the controller of the X-ray residual stress measuring system which concerns on this Embodiment. It is a figure which shows an example of two-dimensional shape data. It is a figure which shows the flow of the X-ray residual stress measuring method which concerns on this Embodiment. (A) The figure which shows an example of a diffraction ring image, (B) The figure which expand | deployed the diffraction ring. It is a figure which shows intensity distribution of the peak position of a diffraction ring. (A) The figure which shows an example of a diffraction ring image, (B) The figure which expand | deployed the diffraction ring. It is a figure which shows intensity distribution of the peak position of a diffraction ring.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. First, an X-ray residual stress measurement system and an X-ray residual stress measurement method according to the present embodiment will be described with reference to FIG. The principle will be described.

  In stress measurement using X-ray diffraction, stress is evaluated by shifting the peak position in the radial direction of the diffraction ring due to the presence of stress (see FIG. 1A). Here, as shown in FIG. 1B, when unevenness exists in the X-ray irradiation region P of the surface S of the measurement object, the X in the measurement object is X in accordance with the transmission path of the diffracted X-rays. Since the distance through which the line passes changes greatly, as shown in FIG. 1C, the peak position in the radial direction of the diffraction ring is apparently shifted, and the shift is calculated as stress. Is significantly reduced.

  When unevenness as shown in FIG. 1B exists in the X-ray irradiation region P of the surface S of the measurement object, a diffraction line having a smaller diffraction angle transmits through the measurement object than a diffraction line having a large diffraction angle. The path becomes longer, more absorbed, the peak intensity becomes smaller, and the peak position apparently shifts.

  Therefore, in the embodiment of the present invention, an uneven shape is measured with a laser or the like on a surface with unevenness for which residual stress evaluation is to be performed, and a region in which a shape in a predetermined direction can be linearly approximated is determined as a measurement region. Next, the X-ray beam diameter is selected so that only the determined measurement region is irradiated with X-rays. X-rays are irradiated to the determined measurement region with the selected X-ray beam diameter, and the residual stress is evaluated. The X-ray incident angle is corrected using the angle formed by the approximate straight line of the determined measurement region with respect to the reference plane, and the residual stress evaluation is performed, and the surface residual stress evaluation of the target sample having an uneven shape such as a curve is performed. Improve accuracy.

(Configuration of X-ray residual stress measurement system)
The X-ray residual stress measurement system 100 according to the present embodiment will be described with reference to FIGS. The system configuration shown in FIGS. 2 and 3 is an example of the X-ray residual stress measurement system 100.

  As shown in FIG. 2, the X-ray residual stress measurement system 100 includes an X-ray diffraction measurement device 10, a three-dimensional shape measurement device 20, a scanning mechanism 32 having a stage 30, a scanning mechanism 82 having a stage 80, The scanning control device 40 and the computer device 50 are included.

  The X-ray diffraction measurement apparatus 10 measures the shape of a diffraction ring generated by X-ray diffraction. The X-ray diffraction measurement apparatus 10 includes an X-ray irradiating unit 11, an imaging plate 12, a reading unit 14, a control unit 15, a table 16 for attaching the imaging plate 12, and a table driving mechanism 17, and X-ray diffraction. The measuring device 10 is connected to the stage 30 and can be driven by a scanning mechanism 32 having the stage 30, a scanning control device 40, and a computer device 50.

  Here, the X-ray irradiation unit 11 includes an apparatus that generates an X-ray by colliding an electron beam with a target, and an X-ray optical system that irradiates the measurement target object with the generated X-ray as a bundle of X-ray beams. I have. The X-ray generator is, for example, an X-ray tube (vacuum tube) for accelerating an electron beam at a high voltage and colliding with an anode to generate Cr-Kα characteristic X-rays. For example, it is a collimator that irradiates the generated X-ray with a narrow beam. The collimator can be switched according to a desired beam diameter.

  The X-ray irradiation unit 11 is supplied with a high voltage and current for X-ray emission from a high-voltage power supply (not shown), and is controlled by the control unit 15 to emit X-rays and irradiate the measurement object OB. Then, a diffraction ring image, which is a diffracted X-ray image, is recorded on the imaging plate 12.

  The control unit 15 is connected to the X-ray irradiation unit 11, the table driving mechanism 17, and the reading unit 14 to control operation and acquire data output from the reading unit 14.

  The control unit 15 is controlled by a controller 51 that configures the computer device 50, and is driven by a high-voltage power source supplied to the X-ray irradiation unit 11 so that X-rays with a certain intensity are emitted from the X-ray irradiation unit 11. Control current and drive voltage. Further, the X-ray irradiation unit 11 includes a cooling device (not shown), and the control unit 15 also controls a drive signal supplied to the cooling device. Thereby, the temperature of the X-ray irradiation part 11 is kept constant.

  The reading unit 14 reads the diffraction ring image recorded on the imaging plate 12. For example, the reading unit 14 irradiates the imaging plate 12 that has imaged the diffraction ring with laser light, reexcites the portion irradiated with the X-rays to emit light, and detects the intensity of light incident from the imaging plate 12. Thereby, the diffraction ring image recorded on the imaging plate 12 is read.

  The reading unit 14 emits visible light from an LED light source (not shown) provided in the reading unit 14 and erases the diffraction ring imaged on the imaging plate 12.

  The table driving mechanism 17 is for rotating and moving the table 16 to which the imaging plate 12 is attached.

  In the state where the imaging plate 12 is at the diffraction ring imaging position (the state shown in FIG. 2), the central axis of a through-hole (not shown) formed in each of the table 16 and the imaging plate 12 and the X-ray of the X-ray irradiation unit 11 The table driving mechanism 17 moves the table 16 so that the optical axis of the line matches. As a result, the X-rays emitted from the X-ray irradiation unit 11 are emitted from the through holes, and the X-rays emitted from the X-ray irradiation unit 11 drive the stage 30 so that a target region on the measurement object OB is obtained. Is irradiated.

  In addition, the imaging plate 12 is driven by the table driving mechanism 17 and moves into a diffraction ring reading region for reading the imaged diffraction ring and a diffraction ring erasing region for erasing the diffraction ring.

  In addition, the X-ray diffraction measurement apparatus 10 includes a case 18 that houses the X-ray irradiation unit 11, the imaging plate 12, the reading unit 14, and the control unit 15.

  The side wall of the case 18 is connected to a support arm 52, and the support arm 52 is a tip of an arm type moving device (not shown). Position and posture can be set. Further, the support arm 52 is connected to the stage 30 and includes a drive mechanism so that X-ray irradiation can be performed on an arbitrary position of the measurement object.

  The three-dimensional shape measuring apparatus 20 measures the uneven shape along the predetermined direction of the surface of the measurement object OB. The three-dimensional shape measuring apparatus 20 is configured using, for example, a laser displacement meter, and irradiates the surface of the measurement object OB with laser light as shown in FIG. 3, and the distance to the laser irradiation point of the measurement object OB. Measure. At this time, the laser irradiation point is scanned in a predetermined direction (X-axis direction in FIG. 4), and the distance to each laser irradiation point is measured along the X-axis direction. As shown in FIG. 4, when the surface of the measurement object OB has irregularities in the X-axis direction and no irregularities in the Y-axis direction, only two-dimensional shape measurement is sufficient. When unevenness exists in the depth direction, the three-dimensional shape is measured by repeatedly performing the two-dimensional unevenness measurement in the depth direction.

  Further, the side wall of the three-dimensional shape measuring apparatus 20 is connected to a support arm 56 having a stage that can be driven in a single axis, and the support arm 56 is a tip of an arm type moving device (not shown). By operating the moving device, the three-dimensional shape measuring device 20 can be set to an arbitrary position and posture.

  The computer device 50 includes a controller 51, a display device 53, and an input device 54.

  The controller 51 is a part that calculates the stress of the measurement object OB from the data obtained by the X-ray diffraction measurement device 10 and the three-dimensional shape measurement device 20, and is configured using, for example, a PC (Personal Computer). ing.

  As shown in FIG. 6, the controller 51 functionally includes a shape measuring unit 60, a measurement region determining unit 62, an angle determining unit 63, a beam diameter selecting unit 64, a diffraction ring imaging control unit 66, and a diffraction ring reading control unit. 68, a diffraction ring elimination control unit 70, an X-ray incident angle correction unit 71, and a residual stress calculation unit 72.

  The shape measuring unit 60 receives a shape measurement start command from the input device 54. At this time, it is assumed that the arm type moving device is operated by the operator, and the irradiation position of the laser light irradiated from the three-dimensional shape measuring apparatus 20 is arranged at the reference position of the measurement object OB. The shape measuring unit 60 controls the three-dimensional shape measuring apparatus 20 to measure the distance to the laser irradiation point by irradiating laser light from the three-dimensional shape measuring apparatus 20 and to scan the laser irradiation point in a predetermined direction. . The shape measuring unit 60 creates two-dimensional shape data of the measurement object OB as shown in FIG. 6 using point cloud data representing the distance to each laser irradiation point input from the three-dimensional shape measuring apparatus 20. Then, the created two-dimensional shape data is displayed on the display device 53.

  The measurement region determination unit 62 determines, as the measurement region, a region whose shape is approximated to a straight line among the concavo-convex shapes along the predetermined direction of the surface of the measurement object OB represented by the two-dimensional shape data. For example, for each combination of two laser irradiation points, a correlation value between the shape between the laser irradiation points of the combination and an approximate straight line is calculated from distance data to each laser irradiation point included in the two-dimensional shape data. The combination of laser irradiation points with a correlation value equal to or greater than a predetermined value (for example, 0.9) is specified, and an area defined by the specified combination of laser irradiation points is set as a measurement area in the measurement area determination unit 62. To decide. Further, the angle determination unit 63 obtains an angle formed between the approximate straight line of the measurement region obtained from the two-dimensional shape data and the reference surface (a surface assumed to be horizontal in the measurement sample), and the X-ray incident angle correction unit 71 The incident angle of the actual X-ray with respect to the approximate straight line specified by the measurement area determination unit 62 is calculated.

  The beam diameter selection unit 64 selects an X-ray beam diameter formed by a switchable collimator that fits within the measurement region size determined by the measurement region determination unit 62, and displays the selected beam diameter. It is displayed on the device 53. Note that the selected X-ray beam diameter is such that a diffraction ring can be formed in the material of the measurement object OB. The operator switches the collimator used in the X-ray diffraction measurement device 10 by looking at the beam diameter displayed on the display device 53.

  The diffraction ring imaging control unit 66 receives a diffraction ring imaging start command from the input device 54. At this time, it is assumed that the arm type moving device is operated by the operator, and the X-ray irradiation position irradiated from the X-ray diffraction measurement apparatus 10 is arranged at the reference position of the measurement object OB.

  The diffraction ring imaging control unit 66 controls the scanning mechanism control unit 40 so that the measurement region determined by the measurement region determination unit 62 is the irradiation position of the X-rays irradiated from the X-ray diffraction measurement apparatus 10.

  In addition, the diffraction ring imaging control unit 66 controls the X-ray diffraction measurement device 10 in a state where the imaging plate 12 is at the imaging position, and causes the X-ray irradiation unit 11 to start emitting X-rays, so that a predetermined time has elapsed. Later, the X-ray irradiation unit 11 stops the emission of X-rays. Thereby, the X-rays emitted from the X-ray irradiation unit 11 are emitted to the outside through the through holes, and are irradiated to the measurement location of the measurement object OB for a predetermined time. By this X-ray irradiation, diffracted X-rays are generated from the X-ray irradiation position of the measurement object OB, and the diffraction ring is imaged on the imaging plate 12.

  The diffraction ring reading control unit 68 controls the X-ray diffraction measurement apparatus 10 to move the imaging plate 12 to a reading start position in the diffraction ring reading region as shown in FIG. The reading start position of the imaging plate 12 is a position where the irradiation position of the laser beam by the reading unit 14 is slightly inside the circle with the diffraction ring reference radius Ro.

  The diffraction ring reference radius Ro is the radius of the diffraction ring formed on the imaging plate 12 by X-ray irradiation on the measurement object OB when the residual stress of the measurement object OB is “0”. It is determined according to the X-ray diffraction angle φx of the object OB and the distance L from the imaging plate 12 to the measurement object OB. The X-ray diffraction angle φx is determined by the material of the measurement object OB, and the distance L is a preset distance. Accordingly, if the diffraction angle φx is stored in advance for each material of the measurement object OB, the controller 51 sets the diffraction ring reference radius Ro to Ro = L · tan (by using the material of the measurement object OB that has been input. It is automatically calculated by the calculation of φx).

  Next, the diffraction ring reading control unit 68 controls the X-ray diffraction measurement apparatus 10 and commands the emission of laser light from the reading unit 14. As a result, the rotating imaging plate 12 is irradiated with laser light. The diffraction ring reading control unit 68 uses the received light intensity output from the reading unit 14 as the radial distance r of the irradiation position of the laser beam from the center of the imaging plate 12 based on the rotation angle θp from the reference position and the moving distance 0. Stored in correspondence with (radius value r).

  Next, the diffraction ring reading control unit 68 controls the X-ray diffraction measurement apparatus 10 to move the imaging plate 12 from the reading start position to the lower right direction in FIG. 2 at a constant speed. Thereby, the irradiation position of the laser light starts to move relative to the imaging plate 12 from the position slightly inside the diffraction ring reference radius Ro toward the outside at a constant speed.

  At this time, the diffraction ring reading control unit 68 uses the received light intensity output from the reading unit 14 as the diameter of the irradiation position of the laser beam from the center of the imaging plate 12 based on the rotation angle θp from the reference position and the movement distance x. The information is sequentially stored in correspondence with the direction distance r (radius value r).

  Thereafter, the diffraction ring reading control unit 68 controls the X-ray diffraction measurement apparatus 10 so that each time the imaging plate 12 rotates by a predetermined small angle, emission of laser light from the reading unit 14 and imaging are performed in the same manner. Relative movement of the plate 12 is performed, and the received light intensity output from the reading unit 14 is determined based on the rotational angle θp from the reference position and the radial distance of the irradiation position of the laser beam from the center of the imaging plate 12 based on the movement distance x. The data are sequentially stored in correspondence with r (radius value r).

  In parallel with the storage operation for each predetermined rotation angle of the data output from the reading unit 14 and the data representing the rotation angle θp and the radius value r, the diffraction ring reading control unit 68 performs the reading unit 14 for each predetermined angle. The radius value r corresponding to the peak of the received light intensity output from is set as the radius value of the diffraction ring.

  The diffraction ring reading control unit 68 controls the X-ray diffraction measurement device 10 to move the imaging plate 12 to the erase start position in the diffraction ring erase region. The erasing start position of the imaging plate 12 is such that the center of visible light output from the LED light source of the reading unit 14 is further inside than the reading start position with respect to the circle having the diffraction ring reference radius Ro. Position.

  Next, the diffraction ring reading control unit 68 controls the X-ray diffraction measurement apparatus 10 to start irradiation of the visible light to the imaging plate 12 by the LED light source of the reading unit 14 and remove the imaging plate 12 from the erasing start position. To the end position of erasing at a constant speed. The erase end position is a position where the center of the LED light from the LED light source is outside the diffraction ring reference radius Ro by the same distance as the erase start position. Thereby, visible light from the LED light source is irradiated onto the imaging plate 12 from the erase start position to the erase end position, and a part of the diffraction ring formed by the diffracted X-rays is erased.

  Thereafter, the diffraction ring reading control unit 68 controls the X-ray diffraction measurement apparatus 10 so that the visible light is emitted from the reading unit 14 and imaged each time the imaging plate 12 rotates by a predetermined small angle. The relative movement of the plate 12 is performed, and the visible light from the LED light source is irradiated on the imaging plate 12 from the erasing start position to the erasing end position for every rotation angle, and all the diffraction rings formed by the diffracted X-rays are Erased.

  The residual stress calculation unit 72 uses the angle formed between the approximate straight line of the measurement region obtained by the measurement region determination unit 62 and the reference plane, and the diffraction ring image obtained by the diffraction ring imaging read control unit 68 by the cos α method. And the residual stress in the measurement region of the measurement object OB is calculated.

Specifically, based on the data representing the shape of the diffraction ring obtained in the above-described reading of the diffraction ring, that is, the radius r of the diffraction ring for each rotation angle, the shape of the diffraction ring and the perfect circle (reference shape) Is calculated as a deformation ε _α using the central angle α of the diffraction ring as a parameter. The central angle α is a central angle formed by a reference line passing through the center of the diffraction ring and a point on the circumference of the diffraction ring, and is also referred to as a circumferential angle α.

The residual stress calculation unit 72 calculates X-axis stress σ _x and shear stress τ _{xy according} to the following equations, assuming that the stress in the measurement region is plane stress.

Where E is the Young's modulus, ν is the Poisson's ratio, η is the residual angle of the diffraction angle, and ψ ₀ is X with respect to a reference surface (the surface on which the stage 30 is mounted) predetermined by the X-ray incident angle correction unit 71. This is an incident angle obtained by correcting the incident angle of the line by an angle formed with the reference plane.

The residual stress calculator 72 displays the calculated X-axis stress σ _x and shear stress τ _xy on the display device 53 as residual compressive stress and residual shear stress at the X-ray irradiation position of the measurement object OB. The operator looks at the magnitudes of the displayed residual compressive stress and residual shear stress, and evaluates the influence on the fatigue strength of the measurement object OB.

(X-ray residual stress measurement method)
Hereinafter, the X-ray residual stress measurement system 100 configured as described above is used to irradiate an iron member as the measurement object OB with X-rays and measure the residual stress of the measurement object OB. A typical method will be described. As shown in FIG. 8, this residual stress is measured by a shape measurement step S100, a measurement region determination step S102, an angle determination step S103, a beam diameter selection step S104, a diffraction ring imaging step S106, a diffraction ring reading step S108, a diffraction ring. This is performed by executing an erasing step S110, an incident angle correcting step S111, and a residual stress calculating step S112. The residual stress calculation step S112 is an example of a diffraction ring evaluation step and a stress calculation step.

  First, the shape measurement step S100 will be described. The operator installs the three-dimensional shape measuring apparatus 20 in the vicinity of the measurement object OB, operates the arm type moving device of the support arm 56 connected to the three-dimensional shape measuring apparatus 20, and operates the three-dimensional shape measuring apparatus 20. Adjust position and posture. This adjustment of the position and orientation is performed by visual observation, and the laser beam irradiated from the three-dimensional shape measuring apparatus 20 is irradiated to the reference position of the measurement object OB. Next, the operator operates the input device 54 to instruct the controller 51 to start the shape measurement step S100. In response to this instruction, the controller 51 acquires measurement data from the three-dimensional shape measuring apparatus 20 and controls the three-dimensional shape measuring apparatus 20 to scan the laser irradiation point in the X direction. Thereby, point cloud data representing the distance to each laser irradiation point in the X direction is obtained. The controller 51 creates two-dimensional shape data of the measurement object OB from the obtained point cloud data, and displays the created two-dimensional shape data on the display device 53.

In the next measurement region determination step S102, the operator first confirms the two-dimensional shape data displayed on the display device 53, and then operates the input device 54 to start the measurement region determination step S102 to the controller 51. Instruct. In response to this instruction, the controller 51 determines the measurement region from the two-dimensional shape data. In the next angle determination step S103, the measurement region is approximated based on the measurement shape of the measurement region obtained from the two-dimensional shape data. Find the angle between the straight line and the reference plane.

  In the beam diameter selection step S104, the controller 51 selects an X-ray beam diameter formed by a switchable collimator that fits within the measurement region size determined in the measurement region determination step, and selects the selected beam. The diameter is displayed on the display device 53. The operator switches the collimator used in the X-ray diffraction measurement device 10 by looking at the beam diameter displayed on the display device 53.

  In the diffraction ring imaging step S106, the operator installs the X-ray diffraction measurement device 10 in the vicinity of the measurement object OB, operates the arm type moving device of the support arm connected to the case 18, and operates the X-ray diffraction measurement device. 10 position and posture are adjusted. The adjustment of the position and orientation is performed by visual observation, and the X-ray emitted from the X-ray diffraction measurement apparatus 10 has an incident angle with respect to the mounting surface (reference surface) of the stage 30 at a predetermined angle, and the measurement object The OB reference position is irradiated.

  Next, the operator operates the input device 54 to input the material of the measurement object OB (in this embodiment, iron) and instructs the controller 51 to start measuring the residual stress. Thereby, the controller 51 first controls the scanning control device 40 in a state where the imaging plate 12 is at the imaging position, and the X-rays emitted from the X-ray diffraction measurement device 10 are determined in the measurement region determination step S102. The stage 30 is moved so that the measurement area of the measurement object OB is irradiated.

  Next, the controller 51 controls the X-ray diffraction measurement apparatus 10 to cause the X-ray irradiation unit 11 to start emitting X-rays, and after a predetermined time has elapsed, the X-ray irradiation unit 11 stops emitting X-rays. Let Thereby, the X-rays emitted from the X-ray irradiation unit 11 are emitted to the outside through the through holes, and are irradiated to the measurement location of the measurement object OB for a predetermined time. By irradiating the measurement object OB with X-rays for a predetermined time, diffracted X-rays are generated from the measurement location of the measurement object OB, and a diffraction ring is imaged on the imaging plate 12.

  After such a diffractive ring imaging step S106, the controller 51 executes the diffractive ring reading step S108 automatically or according to an instruction from the operator using the input device 54.

  The controller 51 controls the X-ray diffraction measurement apparatus 10 to move the imaging plate 12 to a reading start position in the diffraction ring reading region. The controller 51 controls the X-ray diffraction measurement device 10 to start the irradiation of the laser light to the imaging plate 12 by the reading unit 14 and rotates the imaging plate 12 at a predetermined constant rotational speed. Next, the controller 51 uses the received light intensity output from the reading unit 14 as the radial distance r () of the irradiation position of the laser beam from the center of the imaging plate 12 based on the rotation angle θp from the reference position and the movement distance x. The data are sequentially stored in correspondence with the radius value r).

  Further, in parallel with the storing operation for each predetermined rotation angle of the data indicating the received light intensity, the rotation angle θp, and the radius value r output from the reading unit 14, the controller 51 outputs the data from the reading unit 14 for each predetermined angle. The radius value r corresponding to the peak of the received light intensity is taken as the radius value of the diffraction ring.

  After such a diffractive ring reading step S108, the controller 51 executes the diffractive ring erasing step S110 automatically or according to an instruction from the operator using the input device 54. In this diffractive ring erasing step S110, the controller 51 controls the X-ray diffraction measuring apparatus 10 to move the imaging plate 12 to the erasure start position in the diffractive ring erasing region.

  Next, the controller 51 controls the X-ray diffraction measurement apparatus 10 to start the irradiation of the visible light from the LED light source of the reading unit 14 to the imaging plate 12 and to move the imaging plate 12 from the erase start position to the erase end position. Until the imaging plate 12 is rotated. Visible light from the LED light source is irradiated spirally on the imaging plate 12 from the erase start position to the erase end position, and the diffraction ring formed by the diffracted X-rays is erased.

  After such a diffraction ring elimination step S110, the controller 51 performs an incident angle correction step S111 automatically or in accordance with an instruction from the operator using the input device 54, and performs X-rays on the measurement region approximated to a straight line. Calculate and correct the incident angle. And the controller 51 performs residual stress calculation process S112.

Based on the data representing the shape of the diffraction ring obtained in the diffraction ring reading step S108, that is, the radius value r of the diffraction ring for each rotation angle, the controller 51 diffracts the radial deviation between the diffraction ring and the perfect circle. The deformation is calculated as the deformation ε _α using the central angle α of the ring as a parameter.

The controller 51 determines the X-axis stress σ _x , based on the angle formed between the approximate straight line of the measurement region obtained in the measurement region determination step S102 and the reference plane and the calculated deformation ε _α of each central angle α. Shear stress τ _xy is calculated. The controller 51 displays the calculated X-axis stress σ _x and shear stress τ _xy on the display device 53 as residual compressive stress and residual shear stress at the X-ray irradiation position of the measurement object OB. The operator looks at the magnitudes of the displayed residual compressive stress and residual shear stress, and evaluates the influence on the fatigue strength of the measurement object OB.

<Example>
The shape of the object to be measured is measured with a laser displacement meter, and the two-dimensional shape data shown in FIG. 7 is obtained. The area near X = 0 mm in FIG. The angle θ [deg] = 20.3 ° formed by the approximate straight line (see the dotted line in FIG. 7 above) and the horizontal plane was calculated. A collimator (φ0.3 mm) having a size within 1 mm of the measurement area was selected.

Here, a diffraction ring image obtained when the X-ray collimator (φ0.3 mm) determined in the measurement region is irradiated with X-rays from the 45 ° direction on the X axis on the XY plane of FIG. 6 is shown in FIG. Shown in (A). FIG. 9A is a three-dimensional display showing the received light intensity by height. FIG. 9B shows an exploded view of only the diffraction ring, and the received light intensity is indicated by the height. As a result of stress analysis in the X direction by the cos α method using deformation of the diffraction ring obtained from the diffraction ring image, σ _x = −79 ± 10 MPa. FIG. 10 shows the intensity distribution at each peak position of the diffraction ring. The difference in the intensity distribution of the diffraction rings in FIG. 10 is caused because the X-ray irradiation direction with respect to the actual measurement object is not 45 °, and it is estimated that an error is caused in the stress analysis.

Next, the diffraction ring image obtained when the X-ray collimator (φ0.3 mm) determined above is irradiated with X-rays from the 45 ° direction on the X-axis on the XY plane in FIG. FIG. 11A shows a corrected diffraction ring image obtained by correcting the angle as 45-20.3 = 24.7 ° and correcting the intensity of the diffraction ring image. FIG. 11A is a three-dimensional display in which the received light intensity is indicated by the height. FIG. 11 (B) shows a state in which only the diffraction ring is cut out and developed, and the received light intensity is indicated by the height. FIG. 11B obtained from this diffraction ring image shows a state in which only the diffraction ring is cut out and developed. As a result of stress analysis in the X direction by the cos α method using the deformation of the diffraction ring obtained from the diffraction ring image and the corrected incident angle, σ _x = −132 ± 13 MPa. FIG. 12 shows the intensity distribution at each peak position of the diffraction ring. The difference in the intensity distribution of the diffraction rings in FIG. 12 is remarkably improved by correcting the incident angle of the X-ray with respect to the measurement object as compared with the case without correction in FIG. It is estimated that the stress evaluation accuracy is improved by performing stress analysis using the ring.

  As described above in detail, according to the X-ray residual stress measurement system and the X-ray residual stress measurement method according to the present embodiment, the concavo-convex shape along the predetermined direction of the surface of the measurement object is measured, and the predetermined direction is measured. In addition to determining the region where the concavo-convex shape is approximated to a straight line as the measurement region, the angle formed with the reference plane is determined, and the X-ray beam diameter is selected so that only the determined measurement region is irradiated with X-rays. Measuring the deformation from the reference shape of the diffraction ring formed by the diffracted X-rays when the measurement region determined using the selected beam diameter is irradiated with X-rays, Even if unevenness exists on the surface of the measurement object by calculating the residual stress of the determined region based on the incident angle of the X-ray with respect to the reference surface and the angle formed with the reference surface, the measurement object The residual stress can be calculated with high accuracy.

  In addition, for the surface with unevenness for which residual stress evaluation is to be performed, the uneven shape is measured with a laser or the like, the region that can be linearly approximated is determined as the measurement location, the angle between the straight line of the region that can be linearly approximated and the reference plane Surface residual stress evaluation of a measurement object having a concavo-convex shape such as a curvature by performing a residual stress evaluation in consideration of the influence on the residual stress evaluation of the concavo-convex shape using the incident angle of the X-ray with respect to the reference surface Accuracy can be improved.

  In the above embodiment, the case where a laser displacement meter is used as the three-dimensional shape measuring apparatus has been described as an example. However, the present invention is not limited to this, and the uneven shape is a palpable uneven shape evaluation method, Alternatively, it may be measured by an evaluation method using various microscopes capable of measuring other uneven shapes. Moreover, although the case where a collimator is used for limiting the X-ray irradiation region has been described as an example, the present invention is not limited to this, and a slit or the like may be used for limiting the X-ray irradiation region.

DESCRIPTION OF SYMBOLS 10 X-ray-diffraction measuring apparatus 11 X-ray irradiation part 12 Imaging plate 14 Reading part 15 Control part 16 Table 17 Table drive mechanism 18 Case 20 Three-dimensional shape measuring apparatus 30, 80 Stage 32, 82 Scan mechanism 40 Operation control apparatus 50 Computer apparatus 51 Controller 53 Display Device 54 Input Device 60 Shape Measurement Unit 62 Measurement Region Determination Unit 63 Angle Determination Unit 64 Beam Diameter Selection Unit 66 Diffraction Ring Imaging Control Unit 68 Diffraction Ring Reading Control Unit 70 Diffraction Ring Erasing Control Unit 71 X-ray Incident Angle Correction Unit 72 Residual stress calculation unit 100 X-ray residual stress measurement system

Claims (6)

A shape measuring step for measuring a concavo-convex shape along a predetermined direction of the surface of the measurement object;
A region determining step for determining a region determined by a portion approximated to a measured uneven shape straight line;
A beam diameter selection step of selecting an X-ray beam diameter so that only the determined region is irradiated with X-rays;
An angle determining step for determining an angle of the determined area with a reference plane;
A diffraction ring measurement step of irradiating the determined region with X-rays at the selected X-ray beam diameter and measuring the shape of the diffraction ring formed by the X-rays diffracted from the determined region. When,
A diffraction ring evaluation step for evaluating deformation of the measured diffraction ring shape from a reference shape;
A stress calculating step of calculating a stress of the determined region from deformation of the evaluated diffraction ring based on an angle formed with the determined reference plane;
X-ray residual stress measurement method including In the region determination step, a region determined by a portion where a correlation value between the measured uneven shape and the approximate straight line is a predetermined value or more is determined,
The X-ray residual stress measurement method according to claim 1, wherein in the angle determination step, an angle formed by the approximate straight line of the determined region and the reference plane is determined.   In the stress calculation step, a cos α method is used based on an angle formed by the deformation of the evaluated diffraction ring, the determined reference plane, and an X-ray incident angle with respect to the reference plane determined in advance. The X-ray residual stress measurement method according to claim 1, wherein the stress in the determined region is calculated. In the stress calculation step, the incident angle obtained by correcting the incident angle of the X-ray with respect to the reference plane and the deformation angle ε _α of each circumferential angle α of the measured diffraction ring with the determined reference plane The X-ray residual stress measurement according to claim 3, wherein the stress in the determined region is calculated using a cos α method based on the Young's modulus, Poisson's ratio, and residual angle of the diffraction angle of the measurement object. Method. 5. The X of claim 4, wherein in the stress calculation step, the stress σ _x and the shear stress τ _xy in the X-axis direction are calculated according to the following equations, assuming that the stress in the determined region is a plane stress. Wire residual stress measurement method.


Where E is the Young's modulus, ν is the Poisson's ratio, η is the reciprocal angle of the diffraction angle, ψ ₀ is the incident angle obtained by correcting the incident angle of the X-ray with respect to the reference plane by the angle formed with the determined reference plane It is a horn. A shape measuring device for measuring the concavo-convex shape along a predetermined direction of the surface of the measurement object;
An X-ray diffraction measurement device for irradiating the surface of the measurement object with X-rays and measuring the shape of a diffraction ring formed by the diffracted X-rays;
An area determination unit that determines an area determined by a portion approximated to a straight line of the measured uneven shape, based on a measurement result by the shape measuring device,
An angle determining unit that determines an angle of the determined region with a reference plane;
A beam diameter selection unit for selecting an X-ray beam diameter so that only the determined region is irradiated with X-rays;
Based on the shape of the diffraction ring measured by irradiating the determined region with X-rays at the selected X-ray beam diameter by the X-ray diffraction measurement apparatus, A diffraction ring evaluation unit that evaluates deformation from a reference shape, and a stress calculation unit that calculates stress in the determined region from deformation of the evaluated diffraction ring based on an angle formed with the determined reference plane A computer including:
X-ray residual stress measurement system.