JP2018194096A - Spring washer, axial force evaluation method and fastening state evaluation method - Google Patents

Abstract

To provide a spring washer which can accurately evaluate an axial force and a fastening state even after the lapse of a long period of time from fastening, and an evaluation method of the axial force and the fasten state using the spring washer.SOLUTION: A spring washer W having flat-plate shaped inclined parts 6-1 to 4 having faces which form prescribed angles with respect to a center axis at equal angular intervals when viewing the angles to a center axial direction of a hole 5a is inserted between a head part of a screw or a bolt and a substance surface of a fastening object, and fastened thereto, and an amount corresponding to strain which is generated at the flat-plate shaped inclined parts 6-1 to 4 is measured. An axial force is evaluated from an average value of the amount corresponding to the strain, and a fastening state is evaluated from a difference between an amount corresponding to strain immediately after the fastening, and an amount corresponding to strain after the lapse of a long period of time. The amount corresponding to the stain can be obtained by measuring residual stress by using an X-ray diffraction measurement device. Strain gauges are pasted to the flat-plate shaped inclined parts 6-1 to 4, and a strain amount may be detected from the strain gauges.SELECTED DRAWING: Figure 1

Description

  The present invention provides a spring washer that is inserted between the head of a screw or bolt and an object when the object is fastened with a screw or bolt, and an amount corresponding to a strain such as a residual stress generated in the spring washer. The present invention relates to a method for evaluating axial force and a fastening state by measuring.

  There are various methods for evaluating the axial force when an object is fastened using screws or bolts, but the inventor of the present application can accurately evaluate the axial force without deteriorating the working efficiency. As disclosed in Patent Document 1 below, a method is disclosed in which a block is inserted between the head of a screw or bolt and an object at the time of fastening, and the residual normal stress on the side surface of the block is measured by an X-ray diffractometer. doing. In this method, the residual normal stress generated in the longitudinal direction of the side surface of the block by tightening screws or bolts has a high correlation with the axial force. Therefore, the correlation between the axial force and the residual normal stress of the block is obtained in advance. After fastening with screws or bolts, the side of the block is subjected to X-ray diffraction measurement to determine the residual normal stress, and this residual normal stress is applied to the correlation obtained in advance to evaluate the axial force. is there. In this method, after the fastening work with screws or bolts, the axial force can be evaluated by another work, and the residual normal stress is not greatly affected by temperature etc. at normal temperature, so another parameter is set. It is not necessary to measure, and the axial force can be evaluated without deteriorating work efficiency. In addition, if the residual normal stress on the side of the block is measured periodically using an X-ray diffraction measurement device, the axial force can be obtained over time, so that the fastening axial force in bridges, plants, etc. can be evaluated. It is effective for.

Japanese Patent Laying-Open No. 2015-215343

  However, the inventor of the present application has a problem that the axial force evaluation method shown in Patent Document 1 has a case where accuracy is deteriorated in the evaluation of the axial force after a long period of time has passed since the fastening. I found out. In addition, in connection with this, it has also been found that there is a problem that the evaluation of the fastening state after a long period of time has passed since the fastening is performed, and that the axial force alone is not sufficient. This problem is due to a change that the plane of the fastening object that is perpendicular to the central axis of the screw or bolt becomes non-perpendicular. One example is that a gap (hereinafter referred to as “floating”) occurs between two objects fastened with screws or bolts. More specifically, as shown exaggeratedly in FIG. 8, when a floating occurs between two objects fastened with a screw or bolt S so as to be inclined with respect to the central axis of the screw or bolt S, The residual normal stress generated on the side surface of the block B placed under the head of the bolt S is not uniform, and the measured value of the residual normal stress at a certain point is obtained by calculating the axial force and the residual normal stress obtained in advance. Even if the axial force is evaluated by applying the above correlation, the evaluation accuracy of the axial force is not good. In addition, even if the axial force is large, if there is a float between two fastened objects, a force to remove the fastening by the screw or bolt S is acting, and tilting as shown in FIG. When the float is generated as described above, this force acts in a direction different from the direction of the central axis of the screw or bolt S, so that it cannot be said that the fastening state of the object is good. The change in which the plane of the object to be fastened is not perpendicular to the center axis of the screw or bolt is the case where earth and sand enter the lower part of the flat plate when the concrete flat plate is fastened on the sloped ground in addition to floating. Yes, in all cases there is the above problem.

  The present invention has been made to solve this problem, and its purpose is to accurately evaluate the fastening axial force and the fastening state of the object even after a long period of time has passed since fastening with screws or bolts. It is to provide a spring washer that can be done. Another object of the present invention is to provide a method capable of accurately evaluating the fastening axial force and the fastening state of the object by measuring the amount corresponding to the strain such as residual stress generated in the spring washer. .

  In order to achieve the above object, a feature of the present invention is a spring washer inserted between the head of the screw or bolt and the surface of the object to be fastened, and the axial direction of the hole through which the screw or bolt penetrates In other words, the spring washer is provided with a plurality of flat inclined portions having a surface that forms a predetermined angle with respect to the central axis at equal angular intervals.

  According to this, by measuring the amount corresponding to the strain of the flat inclined portion of each spring washer, the axial force and the fastening state of the object when fastened by screws or bolts can be accurately evaluated. Can do.

  Specifically, in the evaluation of the axial force, when the spring washer is inserted and fastened with screws or bolts, an amount corresponding to the strain generated in each flat inclined portion of the spring washer is measured. A strain measurement step and an axial force evaluation step of calculating an average value of an amount corresponding to a plurality of strains acquired in the strain measurement step and evaluating an axial force from the acquired average value are performed.

  According to this, when a change occurs in which the plane of the object fastened with the screw or bolt becomes non-perpendicular to the central axis of the screw or bolt, the strain generated in each flat inclined portion of the spring washer becomes a different value. However, since the value obtained by averaging these values is the same value as when the strain is uniformly generated in each flat plate inclined portion of the spring washer, the axial force can be accurately evaluated.

  Further, in the evaluation of the fastening state, when the spring washer is inserted and fastened with screws or bolts, immediately after the spring washer is inserted and fastened, it is applied to each flat inclined portion of the spring washer. A first strain measurement step for measuring an amount corresponding to the generated strain, and after a predetermined time has elapsed, measure an amount corresponding to the strain generated in each flat plate inclined portion of the spring washer The difference between the amount corresponding to the strain acquired in the second strain measuring step, the strain acquired in the first strain measuring step, and the amount corresponding to the strain acquired in the second strain measuring step is calculated as a strain generation amount. Then, a fastening state evaluation step of evaluating a fastening state from the obtained plurality of strain generation amounts is performed.

  According to this, when a change in the fastening direction occurs at the position of the plane of the object fastened with the screw or bolt, the strain generation amount of each flat plate-like inclined portion is obtained at a certain value, and the center axis of the screw or bolt is obtained. When a change occurs in the plane position of the fastening object so as to be inclined, the strain generation amount of each flat plate-like inclined portion is obtained with a different value, so that it can be seen how the change occurs. Further, when the screw or bolt is loosely tightened, the amount of strain generation is obtained with the opposite sign to the change in the planar position of the fastening object. That is, according to this, a fastening state can be evaluated accurately.

  In addition, the amount corresponding to the strain is measured when an X-ray emitter that emits X-rays toward the target measurement object and when X-rays are irradiated from the X-ray emitter toward the measurement object. The diffracted X-rays generated by the object are received by an imaging surface perpendicular to the optical axis of the X-rays emitted from the X-ray emitter, and a diffraction ring that is an image of the diffracted X-rays is formed on the imaging surface. An X-ray diffractometer having an diffractive ring forming means to be formed is used to irradiate a flat inclined portion of a spring washer with X-rays emitted from an X-ray emitter to form a diffractive ring on an imaging surface. It may be obtained by performing a step and a residual stress calculation step of detecting the shape of the diffraction ring imaged on the imaging surface in the imaging step and calculating a residual stress or a value corresponding to the residual stress.

  According to this, the amount corresponding to the strain can be obtained as the residual stress or the value corresponding to the residual stress without deteriorating the working efficiency, so that the axial force and the fastening state can be evaluated efficiently.

  Further, in the evaluation of the fastening state, when the spring washer is inserted and fastened with screws or bolts, immediately after the spring washer is inserted and fastened, it is applied to each flat inclined portion of the spring washer. A strain gauge attaching step for attaching a film-like strain gauge, a strain measuring step for detecting an amount corresponding to strain from each strain gauge after a predetermined time has elapsed, and a plurality of strains acquired in the strain measuring step. It is further preferable to perform a fastening state evaluation step of evaluating the fastening state from an amount corresponding to.

  According to this, since the amount of strain generation can be obtained by detecting the amount corresponding to the strain from the strain gauge, there is no need to perform the measurement by the X-ray diffraction measuring apparatus, and immediately after the fastening is performed. The amount corresponding to the strain does not need to be recorded in correspondence with each flat plate inclined portion of the spring washer, and the fastening state can be evaluated more efficiently.

It is a whole external view which shows embodiment of the spring washer by this invention. It is a figure which exaggerates and shows a deformation | transformation of the spring washer when a float arises between two objects after inserting and fastening the spring washer of FIG. 1 is an overall schematic diagram showing an X-ray diffraction measurement system including an X-ray diffraction measurement device used when measuring strain by residual stress. It is an enlarged view of the X-ray-diffraction measuring apparatus of FIG. It is a fragmentary sectional view which expands and shows the part which the X-ray passes in the X-ray-diffraction measuring apparatus of FIG. It is an expansion perspective view of the plate part of FIG. It is a whole external view which shows the state which stuck the film-form strain gauge on the spring washer of FIG. In the evaluation of axial force after a long period of time, it is a figure which shows that axial force may not be accurately evaluated with the prior art.

  The spring washer W in the embodiment of the present invention is shown in FIG. As shown in FIG. 1, the spring washer W has a square central plane portion 5 in which a hole 5 a for inserting a screw or a bolt is opened, and four rectangular flat plates around the central plane portion 5. The inclined portions 6-1 to 6-4 are connected so as to be symmetrical with each other. The flat plate-like inclined portions 6-1 to 6-4 form an angle of 20 to 50 degrees with the central plane portion 5, and this angle and the length in the longitudinal direction are any flat plate-like inclined portions 6-1 to 6-6. The same applies to -4. The flat inclined portions 6-1 to 6-4 have a rectangular parallelepiped shape having a lower surface parallel to the plane of the central plane portion 5 on the opposite side to the side connected to the central plane portion 5, as described above. Since the angle formed with the central plane part 5 of the flat inclined parts 6-1 to 6-4 and the length in the longitudinal direction are the same, the four lower surfaces are in one plane. Therefore, when the spring washer W is placed at a fastening location that is a flat surface, the four lower surfaces are in contact with the plane of the fastening location, the central plane portion 5 is parallel to the plane of the fastening location, and the central axis of the hole 5a is the center of the fastening location. Be perpendicular to the plane. The material of the spring washer W may be any material as long as it has elasticity and X-ray diffraction measurement is possible (the intensity of diffracted X-rays is large), and iron, SUS, or the like can be used.

  Immediately after the spring washer W shown in FIG. 1 is inserted between the head of the screw or bolt and the object to be fastened, a force is applied in the normal direction of the central flat portion 5 (the central axis direction of the hole 5a). Therefore, distortion occurs equally in the four flat inclined portions 6-1 to 6-4. Since this strain increases as the axial force due to fastening, that is, the force applied to the four flat inclined portions 6-1 to 6-4 increases, there is a high correlation between strain and axial force. When the force applied in one direction is large, the strain in that direction can be regarded as equivalent to the residual normal stress in that direction, so the four flat inclined portions 6-1 to 6-4 in the long direction Residual normal stress is highly correlated with axial force. Therefore, if this correlation is obtained in advance, the fastening axial force is evaluated by measuring the amount corresponding to the residual normal stress of the four flat inclined portions 6-1 to 6-4 or other strains. be able to.

  And if a long time passes and the change of plane positions, such as a float, arises in a fastening object, or a fastening loosens, the distortion which has occurred in four flat inclined parts 6-1 to 6-4 will change. The relationship between strain and axial force and the relationship between residual normal stress and axial force can be regarded as not changing over a long period of time if the spring washer W is the same. The axial force of fastening can be similarly evaluated by measuring an amount corresponding to the strain of. However, as shown in an exaggerated manner in FIG. 2, when the float is inclined with respect to the fastening direction (the central axis of the screw or bolt S), the strain generated in the four flat inclined portions 6-1 to 6-4. Does not occur uniformly. Therefore, the amount corresponding to the residual normal stress or strain other than the four flat inclined portions 6-1 to 6-4 is measured, the obtained values are averaged, and the axial force is evaluated by the average value. Since the four flat inclined portions 6-1 to 6-4 are in symmetrical positions, the average value is equal when the four flat inclined portions 6-1 to 6-4 are uniformly distorted with the same axial force. Therefore, the axial force can be evaluated with high accuracy.

  Further, the difference between the value immediately after fastening and the value after a long period of time has elapsed between the strain generated in the four flat inclined portions 6-1 to 6-4 and the newly generated strain. Since this difference can be regarded as highly correlated with the amount of change in the planar position of the fastening object or the looseness of the fastening, the fastening state can be evaluated from this difference. The difference between the amount corresponding to the strain immediately after the fastening and the amount corresponding to the strain after a long period of time is hereinafter referred to as a strain generation amount. The strain generation amount of the four flat inclined portions 6-1 to 6-4 after a long period of time is measured and memorized by measuring the amount corresponding to the residual normal stress immediately after fastening or other strain. Then, it can be acquired every time the amount corresponding to the residual normal stress or other strains of the four flat inclined portions 6-1 to 6-4 is measured. As shown in an exaggerated manner in FIG. 2, when the float is inclined with respect to the fastening direction (the central axis of the screw or bolt S), the amount of strain generated in the four flat inclined portions 6-1 to 6-4. Since the values are different from each other, it is possible to evaluate not only the amount of occurrence of floating but also the manner of occurrence of floating.

  As described above, the amount corresponding to the strain of the four flat inclined portions 6-1 to 6-4 can be obtained by measuring the residual normal stress with an X-ray diffraction measurement apparatus. Hereinafter, the configuration of an X-ray diffraction measurement system including an X-ray diffraction measurement apparatus that measures the residual normal stress of the four flat inclined portions 6-1 to 6-4 will be described with reference to FIGS. However, this X-ray diffraction measurement system is different from the X-ray diffraction measurement system shown in Patent Document 1 of the prior art document only in the arrangement of the unit to which the LED light source 44 is attached. The configuration is the same. Therefore, the part already demonstrated by the X-ray-diffraction measurement system shown by patent document 1 is only demonstrated briefly.

  This X-ray diffraction measurement system is transported and set to a place where there is a spring washer W for evaluating the axial force and the fastening state of the fastening with the screw or bolt S. As shown in FIGS. 3 and 4, the X-ray diffraction measurement apparatus includes an X-ray emitter 10, a table 16 to which an imaging plate 15 is attached, a table driving mechanism 20 that rotates and moves the table 16, and a diffraction ring. And a laser detection device 30 for detecting. The X-ray diffraction measurement system includes an arm type moving device (not shown), a computer device 90, and a high voltage power supply 95 together with the X-ray diffraction measurement device. The housing 50 also includes various circuits that are connected to the computer device 90 to control operation and input detection signals. A two-dot chain line shown outside the housing 50 in FIG. Various circuits surrounded by are enclosed in a two-dot chain line in the housing 50.

  The casing 50 is formed in a substantially rectangular parallelepiped shape, and includes a bottom wall 50a, a front wall 50b, a rear wall 50e, a top wall 50f, a side wall (not shown), and corners of the bottom wall 50a and the front wall 50b. It is formed to have a notch wall 50c and a connecting wall 50d provided so as to be cut out from the front side to the back side of the sheet. The notch wall 50c is composed of a flat plate perpendicular to the bottom wall 50a and a parallel plate, and the connecting wall 50d is perpendicular to the side wall and has a predetermined angle with the bottom wall 50a. This predetermined angle is, for example, 30 to 45 degrees. One of the side walls is provided with a connection portion (not shown) connected to the support arm 51, and the connection portion is rotatable around the vertical direction of the paper surface of FIGS. The support arm 51 is a tip of an arm type moving device, and the case 50 (X-ray diffraction measuring device) can be set to an arbitrary position and posture by operating the arm type moving device.

  The X-ray emitter 10 extends in the left-right direction in the figure at the upper part in the case 50 and is fixed to the case 50. The X-ray emitter 10 is supplied with a high voltage from a high-voltage power supply 95 and receives X-rays at the bottom. Emits in the direction. When a command is input from the controller 91, the X-ray control circuit 71 outputs a driving current supplied to the X-ray emitter 10 from the high voltage power supply 95 so that X-rays with a constant intensity are emitted from the X-ray emitter 10. Control drive voltage. In addition, the X-ray emitter 10 includes a cooling device (not shown), and the X-ray control circuit 71 also controls a drive signal supplied to the cooling device.

  The table driving mechanism 20 is fixed to the housing 50 and includes a moving stage 21 below the X-ray emitter 10. The moving stage 21 is sandwiched between a pair of opposed plate-like guides 25, 25 in the table driving mechanism 20, and is output by a feed motor 22, a screw rod 23, and a bearing portion 24 fixed to the table driving mechanism 20. It moves in a plane parallel to the side wall of the housing 50 including the X-ray optical axis and in a direction perpendicular to the optical axis of the outgoing X-ray. An encoder 22a is incorporated in the feed motor 22, and the encoder 22a outputs a pulse train signal that alternately switches between a high level and a low level each time the feed motor 22 rotates by a predetermined minute rotation angle. And output to the feed motor control circuit 73.

  The position detection circuit 72 and the feed motor control circuit 73 operate according to commands from the controller 91. Immediately after the start of measurement, the feed motor control circuit 73 outputs a drive signal to the feed motor 22 so as to move the moving stage 21 toward the feed motor 22, and the position detection circuit 72 indicates that the moving stage 21 has reached the movement limit position. When the pulse train signal is no longer input from the encoder 22a, a signal indicating that the drive signal is stopped is output to the feed motor control circuit 73, and the count value is set to “0”. Thus, the feed motor control circuit 73 stops outputting the drive signal. This movement limit position becomes the origin position of the moving stage 21, and the position detection circuit 72 thereafter counts the pulse train signal from the encoder 22a every time the moving stage 21 moves, and adds or subtracts the count value depending on the moving direction. The movement distance x from the movement limit position is output as a position signal. When the feed motor control circuit 73 inputs the destination position of the moving stage 21 from the controller 91, the feed motor 22 is driven forward or backward until the position signal input from the position detection circuit 72 becomes equal to the input destination position. To do. Further, when the moving speed of the moving stage 21 is input from the controller 91, the feed motor control circuit 73 calculates the moving speed of the moving stage 21 using the number of pulses per unit time of the pulse train signal input from the encoder 22a. The feed motor 22 is driven so that the calculated movement speed becomes the input movement speed.

  The upper ends of the pair of guides 25, 25 are connected by a plate-like upper wall 26, and a through hole 26 a is provided in the upper wall 26, and the center position of the through hole 26 a is the emission of the X-ray emitter 10. Opposite the center position of the mouth 11, the outgoing X-rays enter the table drive mechanism 20 through the outgoing opening 11 and the through hole 26a. In a state where an imaging plate 15 (described later) is at the diffraction ring imaging position (the state shown in FIGS. 3 to 5), a through hole is provided at a position facing the through hole 26a of the moving stage 21 as shown in an enlarged view in FIG. 21a is formed. The moving stage 21 is assembled with a spindle motor 27 whose center of rotation is the position of the central axis of the emission port 11 and the through holes 26a, 21a. The output shaft 27a of the spindle motor 27 is cylindrical and has a circular cross section. Have A through hole 27b is provided on the opposite side of the output shaft 27a of the spindle motor 27, and a cylindrical passage member 28 for reducing the inner diameter of a part of the through hole 27b is provided on the inner peripheral surface of the through hole 27b. Is fixed.

  An encoder 27c is incorporated in the spindle motor 27. The encoder 27c controls a pulse train signal that alternately switches between a high level and a low level every time the spindle motor 27 rotates by a predetermined minute rotation angle. It outputs to the circuit 74 and the rotation angle detection circuit 75. Furthermore, the encoder 27c outputs an index signal that switches from the low level to the high level for a predetermined short period of time for each rotation of the spindle motor 27 to the controller 91 and the rotation angle detection circuit 75.

  When the rotation speed is input from the controller 91, the spindle motor control circuit 74 outputs a drive signal so that the rotation speed calculated from the number of pulses per unit time of the pulse train signal input from the encoder 27c becomes the input rotation speed. Output to the spindle motor 27. The rotation angle detection circuit 75 counts the number of pulses of the pulse train signal input from the encoder 27c, calculates the rotation angle θp from the count value, and outputs it to the controller 91. In addition, when the index signal is input from the encoder 27c, the rotation angle detection circuit 75 resets the count value to “0”. This is the position at a rotation angle of 0 °. Note that the position of the imaging plate 15 at a rotation angle of 0 ° means that the laser beam is irradiated when an index signal is input when a diffraction ring formed on the imaging plate 15 is read by laser irradiation from a laser detection device 30 described later. It is a position that has been. Since this position is at each radial position of the imaging plate 15, it is a line.

  The table 16 has a circular shape and is fixed to the tip of the output shaft 27 a of the spindle motor 27. The table 16 has a protruding portion 17 that protrudes downward from the central portion of the lower surface, and a thread is formed on the outer peripheral surface of the protruding portion 17. An imaging plate 15 is attached to the lower surface of the table 16. A through hole 15 a is provided in the center of the imaging plate 15, and the projection 17 is passed through the through hole 15 a, and a nut-shaped fixture 18 is screwed onto the outer peripheral surface of the projection 17, thereby imaging plate 15. Is fixed between the fixture 18 and the table 16. The fixture 18 is a cylindrical member, and a thread corresponding to the thread of the protrusion 17 is formed on the inner peripheral surface.

  The table 16, the protruding portion 17, and the fixture 18 are also provided with through holes 16 a, 17 a, and 18 a, and the inner diameter of the through hole 18 a is the same as the inner diameter of the passage member 28. That is, the emitted X-rays are emitted through the through holes 26a and 21a, the passage member 28, the through holes 27b, 27a1, 16a, 17a and 18a, and the inner diameter of the passage member 28 and the inner diameter of the through hole 18a are small. The X-ray emitted from the hole 18a becomes parallel light parallel to the axis of the through hole 27a1, and is emitted from the circular hole 50c1 of the housing 50.

  The imaging plate 15 moves to the diffraction ring imaging position together with the moving stage 21, the spindle motor 27, and the table 16, and also includes a diffraction ring reading region for reading the imaged diffraction ring, which will be described later, and a diffraction ring erasing region for erasing the diffraction ring. Move to. In this movement, the central axis of the imaging plate 15 is maintained in a plane formed by the optical axis of the outgoing X-ray and the position (line) at a rotation angle of 0 ° in the imaging plate 15, and the optical axis of the outgoing X-ray. Move in a direction perpendicular to.

  The laser detection device 30 irradiates the imaging plate 15 that images the diffraction ring with laser light, and detects the intensity of the light emitted from the imaging plate 15. The laser detection device 30 is sufficiently separated from the imaging plate 15 at the diffraction ring imaging position toward the feed motor 22 so that X-rays diffracted by the measurement object are not blocked by the laser detection device 30. The laser detection device 30 is an optical head including a laser light source 31, a collimating lens 32, a reflecting mirror 33, a dichroic mirror 34, an objective lens 36, and the like, and has the same configuration as that used for recording and reproduction of an optical disc. When a command is input from the controller 91, the laser drive circuit 77 outputs a drive signal to the laser light source 31 so that the intensity of the signal input from the photodetector 42 becomes a predetermined intensity. Laser light with a constant intensity is emitted from the laser light source 31. The photodetector 42 reflects a small amount by a dichroic mirror 34 to be described later, and outputs a signal having an intensity corresponding to the intensity of the laser beam received through the condenser lens 41, but the ratio of reflection at the dichroic mirror 34 is constant. Therefore, it can be considered that a signal having an intensity corresponding to the intensity of the emitted laser light is output. The collimating lens 32 collimates the laser light, the reflecting mirror 33 reflects the laser light toward the dichroic mirror 34, and the dichroic mirror 34 transmits most of the incident laser light (for example, 95%) as it is. The objective lens 36 focuses the laser light on the surface of the imaging plate 15. A focus actuator 37 is assembled to the objective lens 36. The focus of the laser light always matches the surface of the imaging plate 15 by a focus servo described later.

  When the focused laser beam is applied to the portion of the imaging plate 15 where the diffractive ring is imaged, a photo-stimulated luminescence phenomenon occurs, corresponding to the intensity of the diffracted X-ray at the time of diffractive ring imaging. Light is generated. The light generated by the stimulated light emission has a wavelength shorter than that of the laser light and passes through the objective lens 36 together with the reflected light of the laser light, but most of the light is reflected by the dichroic mirror 34, and the reflected light of the laser light is Most are transparent. The light reflected by the dichroic mirror 34 enters the photodetector 40 via the condenser lens 38 and the cylindrical lens 39. The photodetector 40 includes a four-part light receiving element including four light receiving elements having the same square shape, and outputs four light receiving signals (a, b, c, d) to the amplifier circuit 78. The cylindrical lens 39 is used to cause astigmatism.

  The amplification circuit 78 amplifies the four received light signals (a, b, c, d) and outputs them to the focus error signal generation circuit 79 and the SUM signal generation circuit 80. The focus error signal generation circuit 79 generates a focus error signal in the astigmatism method and outputs the focus error signal to the focus servo circuit 81. The focus servo circuit 81 starts to operate when a command is input from the controller 91, generates a focus servo signal based on the input focus error signal, and outputs the focus servo signal to the drive circuit 82. The drive circuit 82 drives the focus actuator 37 in accordance with the input focus servo signal to displace the objective lens 36 in the direction of the optical axis of the laser beam, so that the focal point of the laser beam is always on the surface of the imaging plate 15. Match.

  The SUM signal generation circuit 80 adds the four received light reception signals to generate a SUM signal and outputs it to the A / D conversion circuit 83. The intensity of the SUM signal is equivalent to the intensity of a small amount of laser light reflected by the imaging plate 15 and reflected by the dichroic mirror 34 and the intensity of light generated by the stimulated emission. Since the intensity of the reflected laser beam is substantially constant, the intensity of the SUM signal corresponds to the intensity of the light generated by the stimulated emission. That is, the intensity of the SUM signal corresponds to the intensity of diffracted X-rays in the imaged diffraction ring. When a command is input from the controller 91, the A / D conversion circuit 83 converts the instantaneous value of the input SUM signal into digital data and outputs it to the controller 91.

  Further, an LED light source 43 is provided adjacent to the objective lens 36. The LED light source 43 is controlled by the LED drive circuit 84 to emit visible light and erase the diffraction ring imaged on the imaging plate 15. When the LED drive circuit 84 receives a command from the controller 91, the LED drive circuit 84 supplies the LED light source 43 with a drive signal for generating visible light having a predetermined intensity.

  The X-ray diffraction measurement apparatus has an LED light source 44. As shown in FIGS. 4 to 6, the LED light source 44 is fixed to the lower surface of one end portion of the plate 45 disposed between the moving stage 21 and the lower surface of the upper wall 26 of the table driving mechanism 20. The plate 45 is fixed to an output shaft 46 a of a motor 46 fixed in the moving stage 21, and rotates in a plane parallel to the lower surface of the upper wall 26 by the rotation of the motor 46. The moving stage 21 is provided with stopper members 47a and 47b. When the plate 45 is rotated in the direction D1 in FIG. 6, the LED light source 44 is moved through the through hole 26a of the upper wall 26 and the moving stage 21. The rotation of the plate 45 is regulated so that it stops at a position (position A) facing the through hole 21a. On the other hand, the stopper member 47b is a position (B position) where the plate 45 does not block between the through hole 26a of the upper wall 26 and the through hole 21a of the moving stage 21 when the plate 45 is rotated in the direction D2 in FIG. The rotation of the plate 45 is restricted so as to be stationary. In other words, the A position is a position where the plate 45 is in the state shown in FIGS. 5 and 6, and the LED light emitted from the LED light source 44 enters the passage of the passage member 28 provided in the through hole 27 a 1 of the spindle motor 27. This is the incident position. The B position is a position where X-rays emitted from the X-ray emitter 10 are not blocked by the plate 45. The LED light source 44 emits LED light according to a drive signal from an LED drive circuit 85 that is controlled by the controller 91. Although the LED light is a diffusing visible light, when the plate 45 is at the A position, a part of the light is emitted from the through hole 18a through the same path as the outgoing X-ray, so that the through hole 27a1 is the same as the outgoing X-ray. Becomes parallel light parallel to the axis.

  The motor 46 includes an encoder 46b. The encoder 46b outputs a pulse train signal that alternately switches between a high level and a low level to the rotation control circuit 86 every time the motor 46 rotates by a predetermined minute rotation angle. When a rotation direction and a rotation start command are input from the controller 91, the rotation control circuit 86 outputs a drive signal to the motor 46 to rotate the motor 46 in the indicated direction. When the input of the pulse train signal from the encoder 46b is stopped, the output of the drive signal is stopped. Thereby, the plate 45 can be rotated to the A position and the B position, respectively.

  An imaging lens 48 is provided on the notch wall 50 c of the housing 50, and an imager 49 is provided inside the housing 50. The image pickup device 49 is constituted by a CCD light receiver or a CMOS light receiver, and outputs a signal having an intensity corresponding to the light reception intensity of each image pickup device to the sensor signal extraction circuit 87. The imaging lens 48 and the imaging device 49 function as a digital camera that captures an image of a region centered on the irradiation point of the LED light on the measurement object at a position set with respect to the imaging plate 15. The position set with respect to the imaging plate 15 is a position where the vertical distance L from the irradiation point of the X-ray and LED light to the imaging plate 15 on the measurement object is a predetermined set distance. In this case, the depth of field by the imaging lens 48 and the imager 49 is set in a range before and after the irradiation point. The sensor signal extraction circuit 87 outputs the signal intensity data for each image pickup device of the image pickup device 49 to the controller 91 together with data for knowing the position (that is, pixel position) of each image pickup device.

  The optical axis of the imaging lens 48 is included in a plane including the optical axis of the X-ray emitted from the X-ray emitter 10 and the rotation reference position line of the imaging plate 15, and the optical axis of the imaging lens 48. The point at which the optical axes of the X-rays and LED light that are irradiated intersect with each other is adjusted to be the point of irradiation of the X-rays and LED light at a set distance from the imaging plate 15. Furthermore, when the incident angle of the X-ray and LED light to the measurement object is a set value, the angle formed by the optical axis of the imaging lens 48 and the normal direction at the X-ray and LED light irradiation point of the measurement object is The angle is equal to the incident angle. Therefore, when the distance from the irradiation point of the X-ray and LED light on the measurement object to the imaging plate 15 is set, and the X-ray and LED light are irradiated at the incident angle set on the measurement object. Since the optical axis of the scattered light of the LED light incident on the imaging lens 48 and the optical axis of the reflected light coincide with the optical axis of the imaging lens 48, the irradiation point of the LED light and the measurement object in the imager 49 The light receiving point of the LED light reflected by the object is generated at the same position. Since the LED light applied to the measurement object is parallel light, the LED light generates scattered light and reflected light that is reflected substantially as parallel light at the irradiation point. The incident light forms an image at the position of the imager 49 to become an irradiation point, and the reflected light incident on the image forming lens 48 is collected by the image forming lens 48 and received by the imager 49 to become a light receiving point. Therefore, the distance from the irradiation point of the LED light to the imaging plate 15 is a set distance, and when the LED light is irradiated at the incident angle set to the measurement object, the signal intensity data output from the imager 49 is used. In the created captured image, the image of the irradiation point and the image of the light receiving point are generated at the same position.

  The computer device 90 includes a controller 91, an input device 92, and a display device 93. The controller 91 is an electronic control unit mainly including a microcomputer including a CPU, ROM, RAM, a large capacity storage device, and the like, and executes various programs stored in the large capacity storage device to perform an X-ray diffraction measurement device. Control the operation of The input device 92 is connected to the controller 91 and is used by an operator to input various parameters, work instructions, and the like. The display device 93 displays on the display screen a photographed image created based on the signal intensity data input from the imager 49, and a cross at a position corresponding to a position where the optical axis of the imaging lens 48 intersects the imager 49. The mark is displayed. The cross point of the cross mark is a distance in which the distance from the irradiation point of the LED light (emitted X-ray) to the imaging plate 15 is set, and the incident light in which the LED light (emitted X-ray) is set on the measurement object. This is a position where an image of an irradiation point and an image of a light receiving point are generated when irradiated at a corner. The vertical line of the cross mark is a line where a plane including the optical axis of the X-ray emitted from the X-ray emitter 10 and the rotation reference position line of the imaging plate 15 intersects the imaging organ 49. If the image of the light receiving point coincides with the vertical line, the measurement direction of the residual normal stress is the direction in which the vertical line is projected onto the object. Further, the display device 93 displays various setting states, operating states, measurement results, and the like of the X-ray diffraction measurement system. The high voltage power supply 95 supplies the X-ray emitter 10 with a high voltage and current for X-ray emission.

  Next, a specific method for measuring the residual normal stress of the flat inclined portions 6-1 to 6-4 of the spring washer W using the X-ray diffraction measurement system including the X-ray diffraction measurement apparatus configured as described above. Will be described. Note that the residual normal stresses of the flat inclined portions 6-1 to 6-4 may be measured in any order, but in the present embodiment, the residual vertical stresses are measured in the order of the assigned numbers. The operator sets the X-ray diffraction measurement system in the vicinity of the spring washer W to be measured, operates the arm type moving device, moves the X-ray diffraction measurement device (housing 50) to the vicinity of the spring washer W, Turn on the power to operate the X-ray diffraction measurement system. Thereafter, the work, operation or processing is performed in the order of the position / orientation adjustment step, the diffraction ring imaging step, the diffraction ring reading step, the diffraction ring elimination step, and the residual stress calculation step. What has already been described in detail in FIG.

  The position and orientation adjustment step is a step of adjusting the position and orientation of the X-ray diffraction measurement device (housing 50) with respect to the flat plate-like inclined portion 6-1 of the washer W. The operator first operates the arm-type moving device to adjust the position and posture of the X-ray diffraction measurement device (housing 50), so that the irradiation point of X-rays (LED light) is roughly a flat inclined portion. The vicinity of the center of 6-1 is set so that the incident direction of the X-rays (LED light) is projected onto the flat inclined portion 6-1 matches the longitudinal direction of the flat inclined portion 6-1.

  Next, the operator inputs to adjust the position and orientation from the input device 92. With this input, the controller 91 outputs a command to each circuit, moves the imaging plate 15 to the diffraction ring imaging position (state shown in FIGS. 3 to 5), and drives the motor 46 to rotate the plate 45 to the A position. The LED light source 44 is turned on. Thereby, LED light which is parallel light is emitted to the outside from the circular hole 50c1 of the housing 50, and is irradiated to the vicinity of the flat plate-like inclined portion 6-1. Further, the controller 91 causes the image pickup signal from the image pickup device 49 to be output from the sensor signal extraction circuit 87 to the controller 91 and causes the display device 93 to display a captured image created from this image pickup signal.

  While viewing the image displayed on the display device 93, the operator operates the arm type moving device to adjust the position and posture of the X-ray diffraction measurement device (housing 50), and the irradiation point of the LED light is flat. Near the center of the inclined portion 6-1, the vertical direction of the cross mark coincides with the longitudinal direction of the flat inclined portion 6-1, and the irradiation point and the light receiving point of the LED light are crosses of the cross mark on the screen. Match the point. As a result, the distance L from the X-ray irradiation point to the imaging plate 15 becomes a set value, and the X-ray is incident at the set incident angle, and the measurement direction of the residual normal stress is the longitudinal direction of the plate-like inclined portion 6-1. become. However, depending on the angle formed with the flat plate inclined portions 6-1 to 6-4 of the spring washer W and the center plane portion 5 of the flat washer, if the light receiving point of the LED light tries to match the cross point of the cross mark on the screen, the housing Since 50 may come into contact with the surface of the object fastened, it is not essential to match the light receiving point of the LED light with the cross point of the cross mark on the screen. When the LED light receiving point does not coincide with the cross point of the cross mark, the reflected light receiving point of the LED light is formed near the middle of the bottom wall 50a or the notch wall 50c in the Y-axis direction in FIG. Like that. In this case, it is necessary to detect the X-ray incident angle, which is performed in a residual stress calculation step described later. When the adjustment is completed, the operator inputs the end of the position / orientation adjustment from the input device 92. Thus, the controller 91 outputs a command to each circuit, turns off the LED light source 44, stops outputting the imaging signal, drives the motor 46, and rotates the plate 45 to the B position. As a result, the X-rays emitted from the X-ray emitter 10 can enter the through hole 21 a of the moving stage 21.

  In the next diffraction ring imaging step, the operator inputs the material (for example, iron) of the spring washer W from the input device 92 and inputs the start of measurement. Accordingly, the controller 91 controls the spindle motor control circuit 74 to rotate the imaging plate 15 at a low speed, and stops the rotation of the imaging plate 15 when the index signal is input from the encoder 27c. Thereby, the diffraction ring is imaged on the imaging plate 15 in a state where the rotation angle is 0 ° at the time of reading the diffraction ring. Next, the controller 91 controls the X-ray control circuit 71 to cause the X-ray emitter 10 to start emitting X-rays. Thereby, the diffraction ring is imaged on the imaging plate 15 by the diffracted X-rays generated at the X-ray irradiation point in the flat inclined portion 6-1 of the spring washer W. Then, after a predetermined time has elapsed, the X-ray control circuit 71 is controlled to cause the X-ray emitter 10 to stop emitting X-rays.

  Next, the controller 91 executes a diffraction ring reading process. The controller 91 controls the feed motor control circuit 73 to move the imaging plate 15 to the reading start position in the diffraction ring reading region. The reading start position is a position where the irradiation position of the laser beam 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 15 when the residual stress of the measurement object is “0”, and the X-ray diffraction angle 2Θm in the material of the spring washer W. (Θm is a Bragg angle) and the distance L from the X-ray irradiation point to the imaging plate 15 is calculated by the following formula: Ro = L · tan (2Θm). Since the X-ray diffraction angle 2Θm is determined by the material of the spring washer W and the distance L is adjusted to a set value, if the diffraction angle 2Θm is stored in advance for each material of the spring washer W, the spring washer W The diffraction ring reference radius Ro can be calculated by inputting the material.

  Next, the controller 91 controls the spindle motor control circuit 74 to rotate the spindle motor 27 at a predetermined rotation speed, and controls the laser drive circuit 77 to irradiate the imaging plate 15 with laser light from the laser detection device 30. The focus servo circuit 81 is controlled to start focus servo. Further, the rotation angle detection circuit 75 is controlled to start the output of the rotation angle θp of the spindle motor 27 (imaging plate 15), and the A / D conversion circuit 83 is controlled to output the data of the instantaneous value I of the SUM signal. Then, the feed motor control circuit 73 is controlled to rotate the feed motor 22, and the imaging plate 15 is moved from the reading start position to the lower right direction in FIGS. 3 and 4 at a constant speed. Thereby, the irradiation position of the laser beam starts to rotate relatively spirally on the imaging plate 15. Thereafter, every time the imaging plate 15 rotates by a predetermined small angle, the controller 91 outputs the data of the instantaneous value I of the SUM signal output from the A / D conversion circuit 83 and the rotation angle θp output from the rotation angle detection circuit 75. And the data of the movement distance x output from the position detection circuit 72 are input and stored in correspondence with each other. The moving distance x is stored after being converted into a radial distance r (radius value r) of the laser beam irradiation position. Accordingly, data representing the instantaneous value I, the rotation angle θp, and the radius value r of the SUM signal is sequentially stored for each predetermined rotation angle corresponding to the irradiation position of the laser beam that rotates in a spiral.

  In parallel with the storing operation for each predetermined rotation angle of the data representing the instantaneous value I, the rotation angle θp, and the radius value r of the SUM signal, the controller 91 sets the instantaneous value I of the SUM signal with respect to the radius value r for each rotation angle θp. A curve is created, and a radius value rα and a SUM signal intensity value Iα corresponding to the peak of the curve are stored. This is a process of obtaining the intensity distribution of the diffracted X-rays in the radial direction for each rotation angle α of the diffraction ring, and obtaining the radius value rα at the location where the intensity of the diffracted X-rays peaks and the intensity Iα corresponding to the intensity of the diffracted X-rays. It is. Then, the radius value rα and the intensity Iα are acquired at all the rotation angles θp (rotation angle α), and when the instantaneous value I of the SUM signal to be detected becomes sufficiently smaller than the intensity Iα, the data storage is finished. . As a result, the intensity distribution corresponding to the intensity of the diffracted X-rays in the diffraction ring is detected by the data group of the instantaneous value I, the rotation angle θp and the radius value r, and the shape of the diffraction ring is detected by the radius value rα for each rotation angle α. It will be done. Thereafter, the controller 91 outputs a command to each circuit, stops the focus servo, stops the irradiation of the laser beam, stops the operation of the A / D conversion circuit 83 and the rotation angle detection circuit 75, and Stop operation. The rotation of the imaging plate 15 is continued.

  Next, the controller 91 executes a diffraction ring elimination process. The controller 91 controls the feed motor control circuit 73 to move the imaging plate 15 to the erase start position in the diffraction ring erase region. The erasure start position of the imaging plate 15 is a position where the center of the LED light output from the LED light source 43 is further inside than the reading start position with respect to the circle having the diffraction ring reference radius Ro. Next, the controller 91 controls the LED drive circuit 84 to irradiate the imaging plate 15 with the LED light from the LED light source 43 and controls the feed motor control circuit 73 so that the imaging plate 15 is moved from the erasing start position. The feed motor 22 is rotated so as to move at a constant speed in the lower right direction in FIGS. 3 and 4 to the erasing end position. The erase end position is a position where the center of the LED light is outside the diffraction ring reference radius Ro by the same distance as the erase start position. Thereby, LED light is irradiated spirally on the imaging plate 15, and the imaged diffraction ring is erased.

  When the imaging plate 15 reaches the erasing end position, the controller 91 controls the feed motor control circuit 73 to stop the movement of the imaging plate 15 and controls the LED drive circuit 84 to stop the irradiation of the LED light to detect the position. The operation of the circuit 72 is stopped, and the spindle motor control circuit 74 is controlled to stop the rotation of the spindle motor 27 (imaging plate 15).

  Next, the controller 91 executes a residual stress calculation process. This is the data of the radius value rα for each rotation angle α which is the shape of the diffraction ring, the distance L from the X-ray irradiation point to the imaging plate 15 and the set value of the X-ray incident angle, and the material of the spring washer W (for example, This is a calculation process for calculating the residual normal stress by calculation using the cos α method using constants such as diffraction angle, Young's modulus, Poisson's ratio and the like that are known values in (Iron). However, the calculation for calculating the residual normal stress uses a known technique, and is described in detail in, for example, Japanese Patent Laid-Open No. 2005-241308, [0026] to [0044], and thus the description thereof is omitted. When the calculation is completed, the controller 91 displays the value of the residual normal stress on the display device 93.

  In the position / orientation adjustment process, when the light receiving point of the LED light is not matched with the cross point of the cross mark on the screen, that is, when the incident angle of the X-ray is not set, the residual vertical stress is calculated. It is necessary to calculate the incident angle of X-rays. The incident angle of the X-ray is calculated using the method shown in Japanese Patent No. 5967491 using the instantaneous value I, the rotation angle θp, and the radius value r, which are data obtained by reading the diffraction ring. In this calculation, since there is a 1: 1 relationship between the amount of change in the peak instantaneous value Iα with respect to the rotation angle θp and the incident angle of the X-rays, this relationship is stored in advance in the memory of the controller 91 and the rotation angle. The amount of change of the peak instantaneous value Iα with respect to θp is calculated, and the obtained amount of change is applied to the stored relationship to determine the X-ray incident angle. Further, instead of the amount of change in the peak instantaneous value Iα with respect to the rotation angle θp, the same calculation is performed using the amount of change in the width (for example, half width) based on the distribution of the instantaneous value I in the radial direction with respect to the rotation angle θp. May be. The theoretical explanation that there is a 1: 1 relationship between the amount of change and the incident angle of X-rays and the specific calculation method of the incident angle of X-rays are described in detail in Japanese Patent No. 5967491. Refer to

  The operator also measures the residual normal stress by the same process as the above-described process at the flat inclined parts 6-2 to 4-4 after the flat inclined part 6-1. Thereby, the residual normal stress of the four flat inclined portions 6-1 to 4 of the spring washer W is obtained, and the axial force and the fastening state can be evaluated as described above.

  As can be understood from the above description, the spring washer W inserted between the head of the screw or bolt S and the surface of the object to be fastened to evaluate the axial force and the fastening state is attached to the screw or bolt. A spring washer W having at least four flat inclined portions 6-1 to 4 having surfaces that form a predetermined angle with respect to the central axis at equal angular intervals when viewed in the central axis direction of the hole 5a that penetrates S. It is said.

  According to this, by measuring the strain of each of the plate-like inclined portions 6-1 to 4 of the spring washer W, the axial force and the fastening state of the object when fastened by the screw or bolt S are accurately determined. Can be evaluated well.

  Specifically, in the evaluation of the axial force, when the spring washer W is inserted and fastened with a screw or a bolt S, the axial force is generated in the respective flat inclined portions 6-1 to 4 of the spring washer W. The amount corresponding to the strain is measured, the average value of the amounts corresponding to the plurality of acquired strains is calculated, and the axial force is evaluated from the acquired average values.

  According to this, when a change occurs in which the plane of the object fastened with the screw or the bolt S is not perpendicular to the central axis of the screw or the bolt, it occurs in each of the flat plate inclined portions 6-1 to 4 of the spring washer W. The strain to be done is different. Since the average value of these values is the same as that when the flat inclined portions 6-1 to 4 of the spring washer W are uniformly strained, the axial force can be accurately evaluated. it can.

  In the evaluation of the fastening state, when the spring washer W is inserted and fastened with screws or bolts S, the respective plates of the spring washer W are immediately after the spring washer W is inserted and fastened. The amount corresponding to the strain generated in the inclined portions 6-1 to 4 is measured, and after a predetermined time has elapsed, the flat inclined portions 6-1 to 4 of the spring washer W are generated. The amount corresponding to the strain is measured, the difference between the amounts corresponding to the two strains is calculated as the strain generation amount, and the fastening state is evaluated from the acquired plurality of strain generation amounts.

  According to this, when a change in the fastening direction occurs in the position of the plane of the object fastened with the screw or bolt S, the strain generation amount of each of the plate-like inclined portions 6-1 to 4 is obtained with a certain value. Alternatively, if the plane position of the fastening object changes so as to be inclined with respect to the central axis of the bolt S, the strain generation amounts of the respective plate-like inclined portions 6-1 to 4 can be obtained with different values. You can see how the change occurs. Further, when the screws or bolts S are loosely tightened, the strain generation amount is obtained with a sign opposite to the change in the planar position of the fastening object. That is, according to this, a fastening state can be evaluated accurately.

  Further, the amount corresponding to the strain is the X-ray emitter 10 that emits X-rays toward the target measurement object, and when the X-rays are irradiated from the X-ray emitter 10 toward the measurement object, The diffracted X-rays generated at the measurement object are received by the imaging plate 15 perpendicularly intersecting the optical axis of the X-rays emitted from the X-ray emitter 10, and the image of the diffracted X-rays on the imaging plate 15. X-ray diffraction measuring apparatus provided with a diffraction ring forming device for forming a diffraction ring as described above, X-rays emitted from the X-ray emitter 10 are applied to the flat inclined portions 6-1 to 4 of the spring washer W. A diffraction ring imaging step of irradiating and forming a diffraction ring on the imaging plate 15, and a diffraction ring for detecting a shape of the diffraction ring imaged on the imaging plate 15 in the diffraction ring imaging step and calculating a value corresponding to the residual normal stress Reading process and residual stress meter It is acquired by performing the process.

  According to this, since the work efficiency is not deteriorated and an amount corresponding to the strain can be obtained as the residual normal stress, it is possible to efficiently evaluate the axial force and the fastening state.

  Furthermore, in carrying out the present invention, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

  In the said embodiment, the quantity corresponded to the distortion | strain of the flat inclined part 6-1-4 immediately after fastening, and the distortion | strain equivalent to the distortion of the flat inclined part 6-1-4 after a long time passed. The amount of strain was calculated as a strain generation amount, and the fastening state was evaluated from this strain generation amount. However, immediately after fastening as shown in FIG. 7, film-like strain gauges 7-1 to 4 are attached to the central portions of the flat inclined portions 6-1 to 4 of the spring washer W. The strain amount may be detected from -1 to 4, and the fastening state may be evaluated in the same manner as in the above embodiment, with this strain amount as the strain generation amount. As the strain gauges 7-1 to 4, it is only necessary to use a strain gauge that can change the electrical resistance change amount into a strain amount because the electrical resistance changes due to deformation of the attached object. According to this, it is not necessary to perform the measurement by the X-ray diffraction measurement device in order to obtain the strain generation amount, and an amount corresponding to the strain immediately after the fastening is made is a flat inclined portion 6-1 of the spring washer W. It is not necessary to record in correspondence with .about.4, and the fastening state can be evaluated more efficiently. The film-like strain gauges 7-1 to -4 may be of any type as long as the detected amount can be accurately converted into the amount corresponding to the strain.

  In the above embodiment, the amount corresponding to the strain is obtained by measuring the residual normal stress using an X-ray diffractometer, but the amount corresponding to the strain can be accurately measured. If so, another method may be used. For example, before the fastening, as shown in FIG. 7, film-like strain gauges 7-1 to 4 are attached to the center portions of the flat inclined portions 6-1 to 4 of the spring washer W to perform fastening, and the strain gauge 7-1 The strain amount may be detected from ˜4. The amount of strain generated after a long period of time may be the difference between the amount of strain at the time of fastening and the amount of strain after the long period of time. After evaluating the axial force at the time of fastening, the strain gauge 7− 1 to 4 may be peeled off, and new strain gauges 7-1 to 4 may be attached, and the detected strain amount may be the strain generation amount.

  In the above embodiment, the residual normal stress is obtained from the shape of the diffraction ring imaged by X-ray irradiation. However, since the purpose is to evaluate the axial force and the fastening state, the shape of the diffraction ring What is obtained from the above may be a value corresponding to the residual normal stress. For example, it may be the slope of the cos α diagram obtained during the calculation of the residual normal stress by the cos α method.

  In the above embodiment, the X-ray diffraction measurement device that images the diffraction ring and reads the diffraction ring images the diffraction ring on the imaging plate 15, scans the laser detection device 30 while irradiating the laser beam, and scans the irradiation position and light. However, any type of apparatus may be used as long as it can image the diffraction ring and read the diffraction ring. For example, an X-ray CCD having a plane as wide as the imaging plate 15 is provided, and when X-ray irradiation from the X-ray emitter 10 is performed, the intensity distribution of diffracted X-rays is generated by an electrical signal output from each pixel of the X-ray CCD. It may be a device for detecting. Further, instead of the X-ray CCD having the same plane as the imaging plate 15, the X-ray CCD having a small size is scanned while detecting the position, and the electric signal output from each pixel of the X-ray CCD and the X-ray CCD. An apparatus that detects the intensity distribution of the diffracted X-rays from the scanning position may be used. In addition, an apparatus using a scintillation counter that detects fluorescence emitted from the scintillator by a photomultiplier tube (PMT) instead of the X-ray CCD may be used.

  Moreover, in the said embodiment, the program which calculates | requires and calculates | requires residual normal stress was assumed to be installed in the controller 91 of the X-ray-diffraction measurement system. However, if the measurement efficiency is not regarded as important, the X-ray diffraction measurement device may read the captured diffraction ring and the residual normal stress may be calculated by another device. In this case, as a method for inputting X-ray diffraction image data to another apparatus, various methods such as a method using a recording medium and a method using a net line or the like can be considered. In addition, if it may take more time, a part or all of the calculation of the above values may be performed manually without using an arithmetic program.

  In the above embodiment, the X-ray diffraction measurement apparatus is an apparatus having a function of imaging a diffraction ring and reading the diffraction ring. However, if the measurement efficiency is not regarded as important, the X-ray diffraction measurement device is used until the diffraction ring is imaged, the imaging plate 15 on which the diffraction ring is imaged is removed from the X-ray diffraction measurement device, and the diffraction ring is read. The diffraction ring may be read by setting.

  In the above embodiment, when the incident angle of the X-ray is not set to the set value, the amount of change in the peak instantaneous value Iα with respect to the rotation angle θp in the read diffraction ring, or the radial instantaneous value I with respect to the rotation angle θp. The incident angle of X-rays is detected from the amount of change in the width (for example, half-value width) based on the distribution of X-rays using the method disclosed in Japanese Patent No. 5967491. However, any method may be used as long as the incident angle of X-rays can be detected with high accuracy. For example, as shown in Japanese Patent No. 6048547, a method of detecting the position of an LED light irradiation point in a captured image by moving LED light having the same optical axis as that of the emitted X-ray may be used. As shown in Japanese Patent No. 6115597, a method of projecting a pattern image onto an object and detecting the shape of the pattern in the captured image may be used.

  Moreover, in the said embodiment, although the spring washer W shall have the four flat plate inclination parts 6-1-4, if importance is not attached to measurement efficiency, five or more flat plate inclination parts may be screwed or It may be provided at equiangular intervals when viewed in the direction of the central axis of the hole 5a into which the bolt S is inserted. Further, if the measurement efficiency is important and the evaluation accuracy of the fastening state is not important, two or three flat inclined portions may be used.

5 ... Central plane part, 6-1-4 ... Flat plate inclined part, 7-1-4 ... Strain gauge, 10 ... X-ray emitter, 15 ... Imaging plate, 15a, 16a, 17a, 18a, 21a, 26a, 27a1, 27b ... through hole, 16 ... table, 18 ... fixing tool, 20 ... table drive mechanism, 21 ... moving stage, 22 ... feed motor, 23 ... screw rod, 27 ... spindle motor, 28 ... passage member, 30 ... laser Detection device, 31 ... laser light source, 36 ... objective lens, 44 ... LED light source, 45 ... plate, 46 ... motor, 47a, 47b ... stopper member, 48 ... imaging lens, 49 ... imaging device, 50 ... housing, 50a ... bottom wall, 50c ... notch wall, 50d ... connecting wall, 51 ... support arm, 90 ... computer device, 91 ... controller, 92 ... input device, 93 ... table Apparatus, 95 ... high voltage power supply, S ... screw or bolt, B ... block, W ... spring washer

Claims (5)

A spring washer inserted between the head of the screw or bolt and the object surface to be fastened;
A spring washer comprising a plurality of plate-shaped inclined portions having surfaces that form a predetermined angle with respect to the central axis at equal angular intervals when viewed in the central axis direction of a hole through which a screw or bolt passes. In the evaluation method of axial force when the spring washer according to claim 1 is inserted and fastened by a screw or a bolt,
A strain measuring step for measuring an amount corresponding to the strain generated in each flat plate inclined portion of the spring washer;
An axial force evaluation method comprising: calculating an average value of an amount corresponding to a plurality of strains acquired in the strain measurement step, and evaluating an axial force from the acquired average value . In the evaluation method of the fastening state after the spring washer according to claim 1 is inserted and fastening is performed with a screw or a bolt, and a predetermined time has elapsed,
A first strain measuring step for measuring an amount corresponding to a strain generated in each flat inclined portion of the spring washer immediately after the spring washer is inserted and fastened;
A second strain measurement step for measuring an amount corresponding to the strain generated in each flat plate-shaped inclined portion of the spring washer after a predetermined time has elapsed;
A difference between the amount corresponding to the strain acquired in the first strain measurement step and the amount corresponding to the strain acquired in the second strain measurement step is calculated as a strain generation amount, and a plurality of acquired A fastening state evaluation method comprising: a fastening state evaluation step for evaluating a fastening state from a strain generation amount. In the axial force evaluation method according to claim 2 or the fastening state evaluation method according to claim 3,
The amount corresponding to the strain is
An X-ray emitter that emits X-rays toward a target measurement object;
When X-rays are radiated from the X-ray emitter toward the measurement object, the diffracted X-rays generated at the measurement object are reflected with respect to the optical axis of the X-ray emitted from the X-ray emitter. Using an X-ray diffraction measurement device comprising a diffraction ring forming means for receiving light at imaging surfaces that intersect perpendicularly and forming a diffraction ring that is an image of the diffraction X-rays on the imaging surface,
An imaging step of irradiating the flat inclined portion of the spring washer with X-rays emitted from the X-ray emitter, and forming a diffraction ring on the imaging surface;
Axial force obtained by detecting the shape of the diffraction ring imaged on the imaging surface in the imaging step and performing a residual stress or a residual stress calculating step of calculating a value corresponding to the residual stress. Evaluation method or fastening state evaluation method. In the evaluation method of the fastening state after the spring washer according to claim 1 is inserted and fastening is performed with a screw or a bolt, and a predetermined time has elapsed,
Immediately after the spring washer is inserted and fastened, a strain gauge affixing step of affixing a film-like strain gauge to each flat inclined portion of the spring washer;
A strain measurement step for detecting an amount corresponding to strain from each strain gauge after a predetermined time has elapsed;
A fastening state evaluation method comprising: a fastening state evaluation step for evaluating a fastening state from an amount corresponding to a plurality of strains acquired in the strain measurement step.

Images