A probe positioning method and device for an X-ray diffraction residual stress measuring instrument

Abstract

The present invention proposes a probe positioning method and device for a residual stress measuring instrument using an X-ray diffraction method. The positioning device includes a first laser source with a wavelength of λ1, a second laser source with a wavelength of λ2, and a third laser source with a wavelength of λ3. The diffraction spots of the second laser source and the third laser source are elliptical, and λ1≠λ2≠λ3. The short axis and long axis of the diffraction spot of the third laser source are equal to the short axis and long axis of the diffraction spot of the second laser source. The second laser source and the third laser source are respectively movably arranged on both sides of the first laser source, and the distance and angle between the second laser source, the third laser source and the first laser source are variable. During positioning, the positional relationship of the first laser source, the second laser source, and the third laser source of the probe is adjusted to meet specific conditions, and then the distance and normal parallel positioning are performed by observing whether the spots of the three laser sources on the surface of the sample to be measured overlap. There is no contact with the detection point throughout the whole process, which can effectively eliminate the error caused by contact.

Description

Technical Field

[0001] The invention relates to the technical field of residual stress detection, in particular to a probe positioning device and a positioning method for measuring residual stress using an X-ray diffraction method. Background Art

[0002] X-ray diffraction method is currently recognized as the most mature and widely used stress measurement method. During the residual stress measurement process, the distance between the detection probe and the detection point needs to be adjusted to a fixed value, and the detection probe must be parallel to the normal line of the detection point, such as Figure 1 shown.

[0003] During the measurement process, the distance between the probe and the detection point is ensured by an electric ruler or manual measurement. There is currently no clear procedure for whether the normal line of the probe and the detection point are parallel, and it can only be judged visually. For large parts, the reliability of visually judging whether the test probe is parallel to the normal line of the detection point is low. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention aims to propose a probe positioning method and device for an X-ray diffraction residual stress measuring instrument, that is, to produce relevant auxiliary devices for the X-ray diffraction residual stress measuring instrument, and to formulate a fast, effective, and non-contact positioning method for the surface of the sample to be tested, so as to ensure that the distance between the probe and the detection point is constant and parallel to the normal of the detection point.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A probe positioning device for an X-ray diffraction residual stress measuring instrument, wherein the probe of the residual stress measuring instrument is equipped with a first laser source, and a first laser beam emitted by the first laser source coincides with the central axis of the probe, the wavelength of the first laser beam is λ1, the constant distance between the probe and the detection point is L, the diffraction spot of the first laser beam emitted by the first laser source in the probe is circular, and the diameter of the diffraction spot is d, and the probe positioning device comprises:

[0007] A second laser source, wherein the wavelength of a second laser beam emitted by the second laser source is λ2, and the diffraction spot of the second laser beam is elliptical;

[0008] a third laser source, wherein the wavelength of the third laser beam emitted by the third laser source is λ3, and λ3≠λ2≠λ1, and the diffraction spot of the third laser beam is elliptical, and the short axis and the long axis of the elliptical diffraction spot of the third laser beam are equal to the short axis and the long axis of the elliptical diffraction spot of the second laser beam;

[0009] The second laser source and the third laser source are movably arranged on both sides of the probe respectively, and the distance and angle between the second laser source and the probe are variable, and the distance and angle between the third laser source and the probe are variable.

[0010] Furthermore, the probe positioning device of the X-ray diffraction residual stress measuring instrument also includes a bracket, which is an arc-shaped bracket, and the second laser source and the third laser source are slidably connected to the bracket.

[0011] As an option, the surface of the bracket is marked with angle markings.

[0012] As an option, the first laser source is a red laser source, the second laser source is a green laser source, and the third laser source is a blue laser source.

[0013] Furthermore, the probe positioning device of the X-ray diffraction residual stress measuring instrument also includes a color sensor, which is located above the sample to be tested and is used to read the color information of the surface of the sample to be tested.

[0014] A probe positioning method for an X-ray diffraction residual stress measuring instrument includes determining a detection point that meets the requirements on the surface of a sample to be tested. The probe positioning method adopts the aforementioned probe positioning device and includes the following steps:

[0015] Step 1: Turn on the first laser source in the probe to form a circular first laser beam diffraction spot with a diameter of d on the surface of the sample to be tested;

[0016] Step 2: Turn on the second laser source and the third laser source, and then adjust the positions and diffraction spot sizes of the second laser source and the third laser source respectively, so that the first laser source, the second laser source, and the third laser source meet the following conditions:

[0017] Condition 1: Let the required constant distance between the probe and the detection point be L, then adjust the length of the line between the center points of the laser beam emission ports of the second laser source and the third laser source to 2L, and the line is tangent to the center point of the first laser beam emission port of the first laser source in the probe, and the tangent point is located at the midpoint of the line, and the line forms an angle of 45° with the second laser beam and the third laser beam;

[0018] Condition 2: The short axes of the elliptical diffraction spots of the second laser beam and the third laser beam are both located in the plane determined by the intersection of the center lines of the first laser beam, the second laser beam and the third laser beam (i.e., the center lines of the first laser beam, the second laser beam and the third laser beam are coplanar); the long axes of the elliptical diffraction spots of the second laser beam and the third laser beam are both perpendicular to the plane determined by the intersection of the center lines of the first laser beam, the second laser beam and the third laser beam (i.e., the center lines of the first laser beam, the second laser beam and the third laser beam are coplanar); the short axis lengths of the elliptical diffraction spots of the second laser beam and the third laser beam are equal to The length of the major axis is equal to d;

[0019] Step three, moving the sample to be tested or moving the first laser source, the second laser source and the third laser source at the same time while keeping the first laser source, the second laser source and the third laser source satisfying conditions 1 and 2, when the diffraction spots of the first laser beam, the second laser beam and the third laser beam on the surface of the sample to be tested completely overlap, the overlapping positions of the laser beam diffraction spots on the surface of the sample to be tested are the detection points that meet the requirements.

[0020] As an optional solution, the first laser source is red light, the second laser source is green light, and the third laser source is blue light. When the first laser beam diffraction spot, the second laser beam diffraction spot, and the third laser beam diffraction spot on the surface of the sample to be tested completely overlap, the overlapping laser beam diffraction spots on the surface of the sample to be tested are white, and a mark is made at the white spot. In actual operation, it is more convenient to judge whether it is completely overlapped by color information. If other colors exist, it means that it is not completely overlapped.

[0021] Furthermore, a color sensor is used to read the color information of the laser beam spot on the surface of the sample to be tested. When the color sensor reads only white color information, the first laser beam diffraction spot, the second laser beam diffraction spot and the third laser beam diffraction spot completely overlap. This solution further improves the convenience of operation.

[0022] The existing residual stress testing methods have the following problems:

[0023] 1) The distance between the residual stress measuring instrument probe and the diffraction point (detection point) is determined by measuring or loading the electron probe to contact the diffraction point. The adjustment process will cause contact with the sample, and the contact process may cause the actual position of the detection point to shift.

[0024] 2) Whether the residual stress measuring instrument probe is parallel to the normal line of the diffraction point is usually determined by visual inspection, which is highly subjective and has large errors, especially for large components.

[0025] Compared with the prior art, the auxiliary device and positioning method of the present invention can quickly determine whether the distance and normal direction between the probe and the detection point meet the requirements. The position can be determined by simply observing whether the laser diffraction spots overlap. There is no need to measure the distance between the probe and the detection point separately, which reduces the errors caused by individual differences among operators. There is no contact with the detection point throughout the process, which can effectively eliminate the errors caused by contact.

[0026] In addition, the present invention can be equipped with a color sensor to intelligently determine whether the three-color light spots overlap, and assist the intelligent positioning of the probe, which is more convenient and quick, and greatly reduces the damage of X-rays to the operator's body during the test process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of a probe positioning device of an X-ray diffraction residual stress measuring instrument;

[0028] Figure 2 This is a schematic diagram of the position relationship between the blue laser source, the green laser source and the probe;

[0029] Figure 3 It is a geometric relationship diagram of the projection of a blue laser beam or a green laser beam on a plane that meets the requirements;

[0030] Figure 4 It is a geometric relationship diagram between the probe and the detection point when the diffraction spots of the red, blue and green laser beams overlap;

[0031] In the figure: 1-probe, 2-second laser source, 3-third laser source, 4-angle marking, 5-bracket, 6-sliding groove. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above-mentioned technical ideas of the present invention, various modifications, substitutions and changes made according to the common technical knowledge and customary means in the field are included in the scope of the present invention.

[0033] 1. Design of a device to assist in positioning the probe of the X-ray diffraction residual stress measuring instrument.

[0034] like Figure 1 and Figure 2As shown, the probe 1 is installed at the center of the bracket 5, and a blue laser source (second laser source 2) and a green laser source (third laser source 3) are respectively installed on the left and right sides of the probe 1 (usually, the first laser source configured in the probe 1 emits a red laser beam) through the bracket 5 and the arc-shaped sliding groove 6 on the bracket 5. Assuming that the required constant distance between the probe 1 and the detection point is L, and the diameter of the diffraction spot of the red laser beam corresponding to the probe 1 is d, the following requirements are met by adjusting the positions of the blue and green laser sources in the sliding groove 6 on the bracket 5:

[0035] 1) The length of the line between the center points of the laser beam emission ports of the blue laser source and the green laser source is 2L ( Figure 2 The connecting line is tangent to the center point of the red laser beam emission port of the probe 1 located at the midpoint of the connecting line. The connecting line forms a 45° angle with the blue laser beam and the green laser beam. The angle is determined by the angle scale 4 on the surface of the bracket 5. The positions of the laser beam emission ports of the blue laser source and the green laser source are adjusted by the mounting structure of the laser source itself. Figure 1 and 2 ;

[0036] 2) Both the blue laser beam and the green laser beam are elliptical diffraction spots, and the short axes of the elliptical diffraction spots of the blue laser beam and the green laser beam are located on the plane formed by the intersection of the center line of the blue laser beam, the center line of the green laser beam and the center line of the red laser beam corresponding to the probe 1 ( Figure 2 As shown), and the length of the short axis of the elliptical diffraction spot is The long axis of the elliptical diffraction spot of the blue laser beam and the green laser beam is perpendicular to the plane where the center line of the blue laser beam, the center line of the green laser beam, and the center line of the red laser beam corresponding to probe 1 are located. The length of the long axis of the elliptical diffraction spot is d (consistent with the diameter d of the circular diffraction spot of the red laser beam corresponding to probe 1). When the blue laser beam and the green laser beam are irradiated to the plane perpendicular to the red laser beam of probe 1, the projection length of the long axis of the elliptical diffraction spot is still d, and at this time the projection length of the short axis of the elliptical diffraction spot on the plane is:

[0037]

[0038] That is, the projection of the elliptical diffraction spot of the blue laser beam and the green laser beam in the plane perpendicular to the red laser beam corresponding to the probe 1 is a circle with a diameter of d. Figure 3 .

[0039] After the above conditions 1) and 2) are met, move the sample to be tested (preferred method) or move the blue laser beam, green laser beam and probe 1 at the same time (generally not recommended). When the elliptical diffraction spots of the blue laser beam and green laser beam completely overlap with the diffraction point of the red laser beam diffraction spot of probe 1, that is, when they overlap into a circular diffraction spot with a diameter of d, the position on the surface of the sample to be tested is a detection point that meets the requirements. Figure 4 At this time, the position relationship between probe 1 and the detection point is as follows:

[0040] 1) The distance between probe 1 and the detection point meets the following requirements:

[0041] 2) The normal of the detection point is parallel to the probe 1. This is because the diffraction spots of the blue laser beam and the green laser beam are ellipses. Only when the normal of the detection point is parallel to the probe 1 (that is, the plane where the diffraction spot of the red laser beam corresponding to the probe 1 is projected at the detection point is perpendicular to the central axis of the probe 1 and is at a 45° angle to the blue laser beam and the green laser beam), the elliptical diffraction spots of the blue laser beam and the green laser beam will completely overlap with the circular diffraction spot of the red laser beam of the central probe 1. Elliptical spots will be observed at other positions, that is, there is no unique circular spot.

[0042] Through the above-mentioned laser beam assisted positioning tool, when the diffraction spots projected by the blue laser beam and the green laser beam at the diffraction point completely overlap with the diffraction spot projected by the red laser beam corresponding to the central probe 1, at this moment, the positional relationship between the probe 1 and the surface of the sample to be tested meets the residual stress test requirements. This is because the spots after the red, blue and green laser beams completely overlap are white. If they do not completely overlap, there will be other colors. When measuring, you can use a black marker pen to blacken the detection point to increase the contrast.

[0043] According to the above principle, the present invention is designed as follows Figure 1 The probe positioning device shown comprises a probe 1, a second laser source 2 and a third laser source 3 mounted on a bracket 5, wherein the probe 1 is centered, and the second laser source 2 and the third laser source 3 are located on the left and right sides of the probe 1, and the second laser source 2 and the third laser source 3 can both slide in an arc shape along the hollow, arc-shaped sliding groove 6 on the bracket 5, and the position adjustment of the center point of the laser beam emission port of the second laser source 2 and the third laser source 3 is achieved by the mounting bracket of the laser source itself (that is, the laser source moves in a plane relative to the mounting bracket, including but not limited to up, down, left and right movement in the plane), and the sliding angle can be read by the angle scale 4 on the upper surface of the bracket 5. When adjusted to an angle of 45° and the line connecting the center points of the laser beam emission ports of the second laser source 2 and the third laser source 3 is tangent to the center point of the laser beam emission port of the first laser source, the second laser source 2 and the third laser source 3 are fastened to the bracket 5 by the locking screws provided on them.

[0044] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. Although the illustrative specific embodiments of the present invention are described above to facilitate the understanding of the present invention by the technical personnel in the field, it should be clear that the present invention is not limited to the scope of the specific embodiments. For ordinary technicians in the field of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A probe positioning device for an X-ray diffraction residual stress measuring instrument, wherein the probe (1) of the residual stress measuring instrument is equipped with a first laser source, and the first laser beam emitted by the first laser source coincides with the central axis of the probe (1), the wavelength of the first laser beam is λ1, the constant distance between the probe (1) and the detection point is L, the diffraction spot of the first laser beam emitted by the first laser source in the probe (1) is circular, and the diameter of the diffraction spot is d, characterized in that: The probe positioning device comprises: a second laser source (2), wherein the wavelength of the second laser beam emitted by the second laser source (2) is λ2, The diffraction spot of the second laser beam is elliptical; A third laser source (3), wherein the wavelength of a third laser beam emitted by the third laser source (3) is λ3, and λ3≠λ2≠λ1, and a diffraction spot of the third laser beam is elliptical, and a short axis and a long axis of the elliptical diffraction spot of the third laser beam are equal to a short axis and a long axis of the elliptical diffraction spot of the second laser beam; The second laser source (2) and the third laser source (3) are movably arranged on both sides of the probe (1), and the distance and angle between the second laser source (2) and the probe (1) are variable, and the distance and angle between the third laser source (3) and the probe (1) are variable; The length of the line between the center points of the laser beam emission ports of the second laser source (2) and the third laser source (3) is 2L, and the line is tangent to the center point of the first laser beam emission port of the first laser source in the probe (1), the tangent point is located at the midpoint of the line, and the line forms an angle of 45° with the second laser beam and the third laser beam; The short axes of the elliptical diffraction spots of the second laser beam and the third laser beam are both located in a plane determined by the intersection of the center lines of the first laser beam, the second laser beam and the third laser beam; the long axes of the elliptical diffraction spots of the second laser beam and the third laser beam are both perpendicular to the plane determined by the intersection of the center lines of the first laser beam, the second laser beam and the third laser beam; the short axis lengths of the elliptical diffraction spots of the second laser beam and the third laser beam are equal to The length of the major axis is equal to d.

2. The probe positioning device of the X-ray diffraction residual stress measuring instrument according to claim 1, characterized in that: It also comprises a bracket (5), which is an arc-shaped bracket, and the second laser source (2) and the third laser source (3) are slidably connected to the bracket (5).

3. The probe positioning device of the X-ray diffraction residual stress measuring instrument according to claim 2, characterized in that: The surface of the bracket (5) is marked with angle markings (4).

4. The probe positioning device of the X-ray diffraction residual stress measuring instrument according to claim 1, characterized in that: The first laser source is a red laser source, the second laser source (2) is a green laser source, and the third laser source (3) is a blue laser source.

5. The probe positioning device of the X-ray diffraction residual stress measuring instrument according to claim 4, characterized in that: It also includes a color sensor, which is located above the sample to be tested and is used to read the color information of the surface of the sample to be tested.

6. A method for positioning a probe of an X-ray diffraction residual stress measuring instrument, comprising determining a detection point that meets the requirements on the surface of a sample to be measured, characterized in that: The probe positioning device according to claim 1 is used, and comprises the following steps: Step 1: turning on the first laser source in the probe (1) to form a circular first laser beam diffraction spot with a diameter d on the surface of the sample to be tested; Step 2: Turn on the second laser source (2) and the third laser source (3), and then adjust the positions and diffraction spot sizes of the second laser source (2) and the third laser source (3) respectively, so that the first laser source, the second laser source (2) and the third laser source (3) meet the following conditions: Condition 1: Let the required constant distance between the probe (1) and the detection point be L, then adjust the length of the line between the center points of the laser beam emission ports of the second laser source (2) and the third laser source (3) to 2L, and the line is tangent to the center point of the first laser beam emission port of the first laser source in the probe (1), the tangent point is located at the midpoint of the line, and the line forms an angle of 45° with the second laser beam and the third laser beam; Condition 2: The short axes of the elliptical diffraction spots of the second laser beam and the third laser beam are both located in the plane determined by the intersection of the center lines of the first laser beam, the second laser beam and the third laser beam; the long axes of the elliptical diffraction spots of the second laser beam and the third laser beam are both perpendicular to the plane determined by the intersection of the center lines of the first laser beam, the second laser beam and the third laser beam; the short axis length of the elliptical diffraction spots of the second laser beam and the third laser beam is equal to The length of the major axis is equal to d; Step three, while keeping the first laser source, the second laser source (2) and the third laser source (3) satisfying conditions 1 and 2, move the sample to be tested or move the first laser source, the second laser source (2) and the third laser source (3) at the same time, when the first laser beam diffraction spot, the second laser beam diffraction spot and the third laser beam diffraction spot on the surface of the sample to be tested completely overlap, the overlapped laser beam diffraction spot position on the surface of the sample to be tested is the detection point position that meets the requirements.

7. The method for positioning a probe of an X-ray diffraction residual stress measuring instrument according to claim 6, characterized in that: The first laser source is red light, the second laser source (2) is green light and the third laser source (3) is blue light. When the first laser beam diffraction spot, the second laser beam diffraction spot and the third laser beam diffraction spot on the surface of the sample to be tested completely overlap, the overlapping laser beam diffraction spots on the surface of the sample to be tested appear white, and a mark is made at the white spot.

8. The method for positioning a probe of an X-ray diffraction residual stress measuring instrument according to claim 7, characterized in that: A color sensor is used to read the color information of the laser beam spot on the surface of the sample to be tested. When the color sensor reads only white color information, the first laser beam diffraction spot, the second laser beam diffraction spot and the third laser beam diffraction spot completely overlap.

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