WO2023112809A1 - 表面検査方法および表面検査装置 - Google Patents

表面検査方法および表面検査装置 Download PDF

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Publication number
WO2023112809A1
WO2023112809A1 PCT/JP2022/045211 JP2022045211W WO2023112809A1 WO 2023112809 A1 WO2023112809 A1 WO 2023112809A1 JP 2022045211 W JP2022045211 W JP 2022045211W WO 2023112809 A1 WO2023112809 A1 WO 2023112809A1
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Prior art keywords
light
screen
spherical surface
sphere
annular
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PCT/JP2022/045211
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English (en)
French (fr)
Japanese (ja)
Inventor
凡輝 孟
哲也 豊内
重信 丸山
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日立建機株式会社
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Priority to CN202280079127.XA priority Critical patent/CN118401827A/zh
Priority to JP2023567733A priority patent/JP7696012B2/ja
Publication of WO2023112809A1 publication Critical patent/WO2023112809A1/ja

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined

Definitions

  • the present invention relates to a surface inspection method and surface inspection apparatus for inspecting the surface condition of a spherical surface.
  • Spherical parts made of metals and ceramics are widely used in rotating mechanisms and sliding parts of industrial machinery, transportation machinery, and precision equipment. is required.
  • steel balls for ball bearings are required to have high dimensional accuracy, such as sphericity of 0.5 ⁇ m or less and surface roughness Ra of 0.040 ⁇ m or less, as one of the general standards. Therefore, a precise surface inspection is essential. For this reason, various inspection methods and inspection apparatuses have conventionally been proposed for industrial spherical parts.
  • Patent Literature 1 describes a surface inspection apparatus that simultaneously rotates a sphere and a laser beam axis while irradiating a sphere to be inspected with a laser beam, detects the amount of reflected light from the sphere, and inspects the surface of the sphere. It is
  • Patent Document 2 describes a method for inspecting the surface of a cylindrical component, although it is not a spherical surface.
  • the magic mirror principle is used to irradiate the surface of a cylindrical part with a sheet of irradiation light having a predetermined width and a predetermined thickness, and the reflected light from the surface of the cylindrical part is projected onto a screen. , the surface condition of the cylindrical part is inspected by observing the optical image formed on the screen.
  • the reflection angle on the spherical surface changes depending on the position where the light is irradiated and the incident angle of the irradiated light.
  • a sphere is an object to be inspected
  • light emitted from the focal point A of the ellipse is applied to one point on the spherical surface arranged at the position of the other focal point B of the ellipse.
  • the angle of reflection of light at the focal point B is not uniform, the spherical surface could not be inspected with the same sensitivity.
  • the illumination light is applied only to one point (focus B) on the spherical surface, the spherical surface cannot be inspected collectively.
  • Patent Document 2 discloses a method for inspecting the surface of a cylindrical component, but does not disclose a method for inspecting the surface of a spherical surface.
  • the present invention proposes a technique for collectively inspecting spherical surfaces with the same sensitivity.
  • one representative surface inspection method of the present invention is to irradiate a spherical surface of an inspection object having a spherical surface with light using a light irradiation device, and reflect light reflected by the spherical surface.
  • a surface inspection method in which an optical image is formed by projecting light onto a screen and the surface condition of a spherical surface is inspected based on the brightness of the optical image.
  • This surface inspection method comprises irradiating a spherical surface with circular light shaped so that the optical axis passes through the center of the spherical surface, and projecting the reflected light reflected by the spherical surface onto the concave surface of the screen to be illuminated.
  • FIG. 1 is a side view showing the configuration of the surface inspection apparatus of Example 1.
  • FIG. 1 is a front view showing the configuration of the surface inspection apparatus of Example 1.
  • FIG. 2 is a side view showing an illumination state of the sphere of the surface inspection apparatus of Embodiment 1;
  • FIG. 4 is a perspective view showing an illumination state of the sphere of the surface inspection apparatus of Embodiment 1;
  • FIG. 2 is a front view showing an illumination state of a sphere of the surface inspection apparatus of Embodiment 1;
  • FIG. 2 is a side view showing the configuration of the rotation mechanism of the surface inspection apparatus of Embodiment 1;
  • the schematic diagram of the optical image acquired with the line sensor camera The figure which shows the optical path of the reflected light from the concave defect of a spherical surface.
  • FIG. 11 is a perspective view showing an illumination state of a sphere of a modified example of the surface inspection apparatus according to the second embodiment;
  • FIG. 1 is a side view showing the configuration of the surface inspection apparatus of Example 1
  • FIG. 2 is a front view showing the configuration of the surface inspection apparatus of Example 1.
  • FIG. The surface inspection apparatus 1 irradiates the spherical surface of the sphere 100 with light, and the reflected light reflected by the spherical surface is applied to a screen having an annular and strip-shaped illuminated surface (hereinafter, this embodiment, and embodiments 3, 6, and 10 to be described later). 7) is projected onto 105 to form an optical image. Then, the surface inspection apparatus 1 inspects the surface condition of the spherical surface based on the brightness of the optical image.
  • the surface inspection apparatus 1 includes a light irradiation device 50 that irradiates the sphere 100 with light.
  • the light irradiation device 50 includes a light generation device (including a laser oscillator that generates laser light in this embodiment) 101 that generates parallel light, a beam expander 102, an axicon lens 103, and an optical system that includes an axicon lens 104. a device 51; Further, the surface inspection apparatus 1 includes an annular screen 105, a line sensor camera 106, a lens 107, a line sensor camera 108, a lens 109, an image processing device 113, a determination device 114, and a holding device 115 for the sphere 100 (see FIG. 6). , provided.
  • At least one of the axicon lens 103 and the axicon lens 104 is movable in the Y-axis direction, and the distance (distance between the axicon lenses) a between the axicon lens 103 and the axicon lens 104 is set to an arbitrary distance. be able to. That is, the optical device 51 has a configuration capable of adjusting the distance between the axicon lens 103 and the axicon lens 104 . Also, the line sensor cameras 106 and 108 are held by a holding mechanism (not shown) and made variable in the Y-axis direction.
  • the surface inspection apparatus 1 also has a controller (not shown) that controls the operations of the above-described devices and mechanisms.
  • the inspection object is the sphere 100, but the inspection object need not be a sphere as long as it has a spherical surface.
  • the test object may be a piston.
  • An example of rotating the piston is described in detail in Example 6.
  • the material of the sphere 100 does not matter as long as it is a material having a predetermined reflectance, such as metal, ceramics, or wood.
  • the laser oscillator 101 constitutes a light generation device 101 that generates parallel light (hereinafter, a case where the light generation device is a laser oscillator will be described).
  • a laser oscillator 101 outputs a parallel beam 10 having a wavelength of 670 nm and a beam diameter of 0.48 mm.
  • the parallel beam 10 is parallel light parallel to the optical axis 10a. Parallel light refers to light in which every ray in the beam is parallel to the other ray.
  • the output of the laser oscillator 101 is, for example, about 1 mW.
  • the parallel beam 10 has a single mode, the intensity distribution of the output beam is a Gaussian distribution, and the 1/ e2 diameter is the beam diameter.
  • the beam diameter is the width of the intensity when the peak intensity drops to 1/e 2 (13.6%).
  • the parallel beam 10 is expanded to have a beam diameter t0 through a beam expander 102.
  • t0 1 mm.
  • the axicon lenses 103 and 104 which are the optical device 51, are conical prism lenses and have the same shape and the same material. Also, the optical axis 10a passes through the vertices of the cones of the axicon lenses 103 and 104 and the vertices of the cones face each other.
  • the parallel beam 10 enters from the flat side of the axicon lens 103 and exits from the conical surface, the parallel beam 10 is refracted at the ridgeline of the cone and directed toward the optical axis 10a. After the parallel beam 10 crosses the optical axis 10a, the parallel beam 10 becomes an annular beam (annular light).
  • the outer diameter of the annular beam increases as the irradiation distance from the axicon lens 103 increases, but the thickness of the annular ring remains constant. This beam characteristic is close to the characteristics of the Bessel beam, and the beam intensity forming the ring is constant regardless of the irradiation distance.
  • the toric beam is then incident on the conical surface of the axicon lens 104 . At this time, since the prism angle ⁇ of the axicon lens 104 is the same as that of the axicon lens 103, the circular beam is refracted by the ridgeline of the cone, and the optical path of the circular beam becomes parallel to the optical axis 10a again.
  • the annular beam parallel to the optical axis 10a is hereinafter referred to as an annular beam 10b.
  • the annular beam 10b has an annular shape centered on the optical axis 10a, and the optical axis 10a passes through the center O of the sphere 100. FIG. Therefore, the annular beam 10b is irradiated on the spherical surface of the sphere 100 at the same angle of incidence.
  • the angle of incidence refers to the angle between the optical axis 10a of the annular beam 10b and the normal to the spherical surface of the sphere 100 irradiated with the annular beam 10b.
  • the angle of incidence of the annular illumination region 110 of the sphere 100 is given by equation (7)' described later. , at substantially the same angle of incidence.
  • the thickness t1 of the annular beam 10b formed in this embodiment will be described.
  • the thickness t1 of the annular beam 10b after passing through the axicon lens 104 is also constant regardless of the irradiation distance from the axicon lens 104.
  • the outer diameter dr of the annular beam 10b can be obtained from Equation (1).
  • dr 2a ⁇ tan((n ⁇ 1) ⁇ )) (1)
  • the outer diameter dr can be adjusted by adjusting the distance a between the axicon lenses.
  • the spherical illumination area 110 of the sphere 100 is indicated by diagonal hatching. The illumination area 110 can be arbitrarily changed by adjusting the outer diameter dr.
  • FIG. 1 The annular beam 10 b is reflected by the spherical surface of the sphere 100 , travels radially around the point O′ on the optical axis 10 a and is projected onto the annular screen 105 .
  • the annular screen 105 is a screen configured such that the surface to be irradiated with reflected light (on the side of the optical axis 10a in this embodiment) is concave.
  • the annular screen 105 of Example 1 is an annular screen arranged along the circumferential direction of a circle centered on the optical axis 10a.
  • FIG. 3 is a side view showing an illumination state of the sphere.
  • the annular screen 105 has a hollow cylindrical shape with a radius L0 and a width W in the Y-axis direction. Also, the cylindrical axis of the annular screen 105 coincides with the optical axis 10a.
  • the ring-shaped screen 105 is installed at a position separated from the center O of the sphere 100 toward the laser oscillator 101 by a distance u0.
  • the reflected light is projected onto the annular screen 105 having a concave surface on the optical axis 10a side, but the screen may not be annular.
  • the annular screen 105 may have a concave surface on the optical axis 10a side, and may have a hemispherical shape.
  • annular screen 105 As shown in FIG. 2, an optical image formed by reflected light projected onto annular screen 105 is scanned in the circumferential direction of annular screen 105 by line sensor cameras 106 and 108 via lenses 107 and 109. , is observed.
  • the line sensor cameras 106 and 108 are arranged on the same side of the rotation axis 11 on the XZ plane as shown in FIG. 2, the visual field range 111 in the circumferential direction of the annular screen 105 including the line sensor cameras 106 and 108 is at least 180° from 0° to (90°) to 180° of the annular screen 105. Covers a range of minutes.
  • the line sensor cameras 106 and 108 when the sphere 100 is rotated once about the rotation axis 11 , the line sensor cameras 106 and 108 also cover the axially symmetrical area of the circumferential viewing range 111 on the annular screen 105 . Therefore, 360° in the circumferential direction on the ring-shaped screen 105 can be accommodated within the combined field of view of the line sensor cameras 106 and 108 . Thereby, the entire illumination area 110 of the sphere 100 can be observed.
  • the observation optical axes 12a and 12b of the line sensor camera 106 and the line sensor camera 108 are arranged so as to pass through the optical axis 10a, and as shown in FIG. are arranged to intersect at a position of 135°.
  • the lens 107 and the line sensor camera 106 are arranged coaxially, and similarly, the lens 109 and the line sensor camera 108 are arranged coaxially.
  • the line sensor cameras 106 and 108 are arranged so as to image the outside of the annular screen 105, but at least one of the line sensor cameras 106 and 108 may be arranged so as to image the inside of the annular screen 105. good.
  • the relationship between the outer diameter dr of the annular beam 10b and the radius r of the sphere 100 and the relationship between the outer diameter dr and the distance a between the axicon lenses in this embodiment will be described with reference to FIG.
  • the two intersections of the sphere 100 and the rotation axis 11 are vertexes T and T', respectively.
  • the angle TOA is set to 45° in this embodiment.
  • the parallel light irradiated to point A is reflected in a direction perpendicular to the optical axis 10 a and projected onto point A' on the annular screen 105 .
  • the light irradiated to the point C on the spherical surface of the sphere 100 is reflected in the direction perpendicular to the optical axis 10a and projected onto the point C' on the annular screen 105, like the reflected light from the point A. .
  • the reflected light from the spherical surface of the sphere 100 may reflect in a direction approaching the rotation axis 11 and interfere with the holding device 115 .
  • FIG. 4 is a perspective view of FIG.
  • the inspection area 112 of the sphere 100 of this embodiment will be described with reference to FIGS. 3 and 4.
  • FIG. 4(a) an illumination area 110 of the annular beam 10b irradiated onto the surface of the sphere 100 is indicated by diagonal hatching. Further, when the sphere 100 is rotated once around the rotation axis 11, the surface area of the sphere 100 passing through the illumination area 110 becomes the area indicated by diagonal hatching in FIG. 4(b).
  • a hatched area in FIG. 4B is called an inspection area 112 .
  • the ratio S of the inspection area 112 to the entire surface of the sphere 100 is obtained by Equation (2) using the radius r of the sphere 100 and the outer diameter dr of the annular beam 10b.
  • the inspection area 112 will be about 70% of the entire surface of the sphere 100 regardless of the radius r of the sphere 100. I understand.
  • the outer diameter dr of the annular beam 10b can be adjusted by the distance a between the axicon lenses according to the equation (1).
  • Observation optical axes 12a and 12b of line sensor cameras 106 and 108 are within a belt-like range surrounded by a circle passing through points A' and C' and a circle passing through points B' and D' on annular screen 105. fits in.
  • the line sensor cameras 106 and 108 are moved in the Y-axis direction so that the observation optical axes 12a and 12b are within the band-shaped range.
  • the same inspection apparatus can inspect the spherical surface.
  • a certain percentage of the entire surface of the sphere 100 can be inspected.
  • FIG. 3 shows the optical path on the YZ plane of the reflected light reflected from the spherical surface of the spherical body 100 irradiated with the annular beam 10b.
  • the spherical surface of the sphere 100 enlarges the annular screen in the width direction, that is, on the YZ plane.
  • the magnification M_YZ is given by equation (4).
  • M_YZ dA'B'/dAB (4)
  • dAB and dA'B' are obtained from equations (5) and (6), respectively.
  • dAB ⁇ r (5)
  • dA′B′ r ⁇ (sin(45°+ ⁇ ) ⁇ sin(45°)) + (L0 ⁇ r ⁇ cos(45°+ ⁇ )) ⁇ tan2 ⁇ (6)
  • the angle ⁇ of the arc AB can be obtained from the thickness t1 of the annular beam 10b by Equation (7).
  • t1 r ⁇ (cos45° ⁇ cos(45°+ ⁇ )) (7)
  • the trigonometric function in equation (7) can be converted to equation (7)' by Taylor expansion and ignoring terms of second order or higher.
  • r 15 mm
  • t1 0.502 mm
  • L0 50 mm
  • the angle of incidence of the annular beam 10b on the illumination area 110 ranges from 42.3° to 45°
  • the angle of incidence of the reflected light from the point B on the annular screen 105 is 5.4°. Reflected light is vertically incident on the point A'.
  • the reflected light obliquely enters at an incident angle of 5.4°, and the brightness is lower than that at the point A'.
  • FIG. 5 shows the optical path in the XZ plane of part of the reflected light reflected from the spherical surface of the spherical body 100 irradiated with the annular beam 10b.
  • Light striking the outer ring of the annular beam is directed to points P and Q, and reflected light reflected from points P and Q is radially reflected around point O' on optical axis 10a, and is projected onto annular screen 105. are projected to points P' and Q' of .
  • the enlargement magnification M_XZ in the circumferential direction of the annular screen 105 by the spherical surface of the sphere 100, that is, on the XZ plane, is the ratio of the distance from the point O' to the point P and the distance from the point O' to the point P'. equal.
  • the distance r1 between O'P is r ⁇ cos 45°
  • the distance between O'P' is L0
  • M_XZ is given by equation (8).
  • M_XZ 1.414 ⁇ L0/r (8)
  • the line scan rate f of the line sensor cameras 106 and 108 it is possible to inspect the optical image at a magnification corresponding to the magnification of the optical image in the width direction of the annular screen 105.
  • FIG. If the rotation time per rotation of the sphere 100 is set to T, the minimum value of the scan rate f of the line sensor cameras 106 and 108 is calculated from equation (9).
  • the radius r of the sphere 100, the radius L0 of the ring-shaped screen 105, the magnification M, and the pixel size c on the ring-shaped screen 105 for one pixel of the line sensor cameras 106 and 108 are assumed.
  • the line sensor cameras 106 and 108 must be driven at a scan rate f of 1882 Hz or higher.
  • the pixel dimension c is assumed to be constant regardless of the observation position of the annular screen 105, and is calculated.
  • the holding device 115 is a device that holds the sphere 100 so as to have a configuration that allows the sphere 100 to rotate around the rotating shaft 11 .
  • the holding device 115 rotates the sphere 100 around a rotation axis 11 passing through the center of the sphere 100 and perpendicular to the optical axis 10a.
  • the holding device 115 has a holder 116 that holds the sphere 100 and a rotation mechanism (for example, a rotation stage) 117 that rotates the holder 116 around the rotation shaft 11 .
  • Retainer 116 is a hollow cylinder.
  • the outer diameter dc of the retainer 116 satisfies the condition of dc/2 ⁇ r ⁇ sin45°. This is because the retainer 116 interferes with the annular beam 10b.
  • FIG. 7 is a schematic diagram of an optical image acquired by the line sensor camera 106.
  • the vertical axis of the optical image in FIG. 7 is the rotation axis direction of the sphere 100 from the vertex T to the vertex T', and the horizontal axis indicates the rotation direction of the sphere 100. As shown in FIG. FIG. FIG.
  • the optical image is magnified 4.71 times in the sphere rotation axis direction and 5.99 times in the sphere rotation direction.
  • Images 31 and 32 shown in FIG. 7 are extracted by the image processing device 113, and defect information such as defect coordinates and defect dimensions are recorded in a storage means (not shown).
  • the image processing device 113 outputs defect information such as defect coordinates and defect dimensions based on the brightness of the images acquired by the line sensor cameras 106 and 108 .
  • This image processing device 113 functions as a detection device for detecting defects on the surface of the sphere 100 .
  • the determination device 114 determines whether or not there is a defect based on the defect dimensions (defect size, defect depth) stored in storage means (not shown). For example, the determination device 114 determines that there is a defect and that the inspection object is defective if there is a defect of a size greater than or equal to a predetermined size or a depth of a defect greater than or equal to a predetermined depth. In addition, the determination device 114 can output information indicating whether the inspection target is good or bad, information indicating the dimensions and depth of defects in the inspection target, and the like to a display unit or the like.
  • the image processing device 113 and the determination device 114 constitute an inspection processing device that performs surface inspection processing of the sphere 100 . This inspection processing device may be mounted, for example, in a controller (not shown) that controls the operation of the entire surface inspection device 1, or may be provided as a separate information processing device.
  • FIG. 8(a) shows the light condensing effect when light is irradiated to the recessed defect 41.
  • FIG. The reflected light from the concave defect 41 is bright in the vicinity of the focal point because the rays are condensed.
  • a focal length F of a concave mirror having a depth d and a width Ld is given by Equation (10).
  • F Ld 2 /8d (10)
  • I(L1) indicates the brightness on the magic mirror image, and the larger I(L1) is, the brighter the condensing part and the higher the sensitivity to defects.
  • spot-like random noise occurs on the annular screen 105 . 2 ⁇ of this speckle intensity is defined as ⁇ N% of the average brightness of the optical image on the annular screen 105 .
  • a guideline for separating the speckle from the condensing effect originating from the defect it is possible to detect when the brightness of the condensing part due to the defect becomes about (1+N/100) times that of the surroundings. .
  • 2 ⁇ of the speckle intensity is estimated as ⁇ 50%.
  • the screen-to-screen distance L1 is known.
  • AA′ in FIG. 3 corresponds to the distance from the defect to the screen, for example.
  • the distance AA' can be obtained from the radius L0 of the annular screen 105 and the radius r of the sphere 100 from equation (15).
  • AA′ L0 ⁇ r ⁇ cos45° (15)
  • the range of the focal length F of the sensitive defect becomes the equation (16).
  • F 16.34 mm (range detected as a dark spot), 21.64 mm ⁇ F ⁇ 214.1 mm (range detected as bright spot) (16)
  • F 31.25 mm, which is detected as a bright spot by the apparatus of this embodiment.
  • the sphere 100 is irradiated with an annular beam 10b, the reflected light from the spherical surface is projected onto an annular screen 105, and the surface of the annular screen 105 is observed to detect minute irregularities on the spherical surface with high sensitivity. can do.
  • (2) By irradiating the sphere 100 with an annular beam 10b having an annular thickness t1 so as to satisfy t1 ⁇ r with respect to the radius r of the sphere 100, the incident angle of the illumination light within the illumination area 110 is are substantially the same. Therefore, the inspection area 112 of the sphere 100 can be inspected with substantially the same sensitivity.
  • the outer diameter dr of the annular beam 10b can be adjusted. This allows spheres with different diameters to be inspected with the same inspection device.
  • the annular screen 105 is annular, all of the annular beam 10b reflected by the spherical surface can be projected onto the annular screen 105 . Moreover, since the light is projected onto the annular screen 105 having diffuse reflection characteristics, stable optical image observation is possible without depending on the reflection characteristics of the spherical body 100 .
  • the defect detection sensitivity can be increased by adjusting the radius L0 of the annular screen 105 .
  • the energy efficiency is better than by making it circular. Since the energy density of light is higher in a circular ring than in a circular ring, the spherical surface can be inspected with high sensitivity. (7) By projecting the light reflected by the spherical surface onto the annular screen 105 having a concave surface on the optical axis 10a side, the spherical surface can be inspected with the same sensitivity.
  • the outer diameter of the annular beam 10b is fixed regardless of the optical path length, and the outer diameter of the annular beam 10b is 0.707 times the diameter of the sphere 100, so that the annular beam 10b The beam 10b can be reflected in a direction perpendicular to the optical axis 10a.
  • the spherical surface of the spherical body 100 having a spherical surface is irradiated with light using the light irradiation device 50, and the reflected light reflected by the spherical surface is projected onto the annular screen 105 to form an optical image.
  • the parallel beam 10 is shaped into a circular ring around the optical axis 10a of the parallel beam 10 by the light irradiation device 50.
  • the beam 10b is projected onto a spherical surface so that the optical axis 10a passes through the center of the spherical surface, and the reflected light reflected by the spherical surface is projected onto the concave surface of the annular screen 105 to be irradiated.
  • the annular beam 10b is annular.
  • the outer diameter of the annular beam 10b is constant regardless of the optical path length, and is shaped so that the outer diameter is 0.707 times the diameter of a sphere having a spherical surface. .
  • the sphere 100 is held by the rotatable holding device 115 and rotated around the rotation axis 11 passing through the center of the spherical surface and perpendicular to the optical axis 10a.
  • the optical image projected onto the annular screen 105 is detected by the line sensor cameras 106 and 108, the radius of the sphere 100 having a spherical surface is r, and the distance between the optical axis 10a and the annular screen 105 is
  • L0 is the distance
  • c is the pixel size on the annular screen 105 for one pixel of the line sensor camera
  • T is the rotation time per rotation of the sphere
  • f is the scan rate of the line sensor cameras 106 and 108, then f ⁇ 2 ⁇ r.
  • the line sensor cameras 106 and 108 are driven under the condition satisfying xM/(Txc).
  • the surface inspection apparatus 1 of Example 1 includes a holding device 115 that holds a sphere 100 having a spherical surface, a light generating device 101 that generates parallel light, and a parallel beam 10 that is circularly formed around the optical axis 10a of the parallel beam 10.
  • the optical device 51 irradiates the annular beam 10b shaped to be circular onto the spherical surface so that the optical axis 10a passes through the center of the spherical surface, and the reflected light from the spherical surface is projected and reflected.
  • An annular screen 105 configured such that the surface to be illuminated with light is a concave surface, and an image processing device 113 that detects defects on the spherical surface based on the brightness of the optical image formed on the annular screen 105. , provided.
  • the optical device 51 includes an axicon lens 103 for shaping the parallel beam 10 into an annular shape, and an annular light beam formed in an annular shape in parallel with the optical axis 10a and in a predetermined direction. and an axicon lens 104 that is molded to a diameter of .
  • the optical device 51 has a configuration capable of adjusting the distance between the axicon lens 103 and the axicon lens 104 .
  • the holding device 115 has a configuration capable of rotating the spherical body 100 around the rotation axis 11 passing through the center of the spherical surface and perpendicular to the optical axis 10a.
  • Example 2 the surface inspection apparatus capable of inspecting the spherical surface with substantially the same sensitivity and inspecting with the same inspection apparatus even if the diameter of the sphere to be inspected changes has been described.
  • the inspection area was limited to a part of the entire spherical surface.
  • FIG. 9 is a plan view showing the configuration of the surface inspection apparatus of Example 2.
  • FIG. 9 in addition to the device configuration of the first embodiment, another set of the same light irradiation device as a light irradiation device 60 for irradiating an annular beam having the same shape is added. That is, as shown in FIG. 9, the surface inspection apparatus 2 includes two light irradiation devices 50 and 60, two light generation devices (laser oscillators in this embodiment) 101 and 201, and two beam expanders 102.
  • the surface inspection apparatus 2 includes two screens (hereinafter referred to as semi-annular screens in this embodiment) 105b having semi-annular band-shaped illuminated surfaces corresponding to the two light irradiation devices 50 and 60, and 205b, two line sensor cameras 106 and 206, two lenses 107 and 207, two line sensor cameras 108 and 208, and two lenses 109 and 209.
  • semi-annular screens having semi-annular band-shaped illuminated surfaces corresponding to the two light irradiation devices 50 and 60, and 205b, two line sensor cameras 106 and 206, two lenses 107 and 207, two line sensor cameras 108 and 208, and two lenses 109 and 209.
  • the first light irradiation device 50 (the light generation device 101 and the optical device 51) and the second light irradiation device (another light irradiation device) 60 (the other light generation device 201 and the other Shielding plates 121 and 221 for shaping the circular beams 10b and 20b into a semi-circular shape are added to the optical device 61), respectively.
  • the optical axis 10a of the first light irradiation device 50 and the optical axis 20a of the second light irradiation device 60 each pass through the center O of the sphere 100 and form an angle of 90° with each other.
  • the rotation axis 11b forms angles of 135° and 45° with the optical axes 10a and 20a, respectively, and is set so that the optical axes 10a and 20a are positioned on the same side of a plane including the rotation axis 11b. Further, the rotation axis 11b exists on the plane formed by the optical axis 10a and the optical axis 20a.
  • the inspection range of the annular beam 10b is the lower half of the sphere 100, and the inspection range of the annular beam 20b is It becomes the upper half of the sphere 100 .
  • the entire spherical surface of the sphere 100 can be inspected.
  • FIG. 10 is a perspective view showing the illumination state of the sphere 100.
  • FIG. 10(a) illustration of the screen is omitted for explanation.
  • a light blocking plate 121 is arranged between the sphere 100 and the axicon lens 104
  • a light blocking plate 221 is arranged between the sphere 100 and the axicon lens 104 .
  • the shielding plates 121 and 221 shape the annular beams 10b and 20b into semi-annular beams 10c and 20c.
  • the illumination area 110c of the semi-annular beam 10c irradiated onto the spherical surface of the sphere 100 is indicated by diagonal hatching.
  • An illumination region 210c of the semi-annular beam 20c irradiated onto the spherical surface of the sphere 100 is indicated by a region surrounded by dotted lines.
  • the semi-annular screens 105b and 205b are semi-annular.
  • the spherical surface of the sphere 100 is irradiated with the semi-annular beams 10c and 20c, and the reflected light is projected onto the semi-annular screens 105b and 205b. This prevents interference between the semi-annular beams 10c and 20c reflected from the spherical surface of the sphere 100 on the screen and physical interference between the screens.
  • FIG. 11 is a plan view of the sphere 100 observed from the direction of the optical axis 10a or 20a, showing the positional relationship between the line sensor camera and the screen. Also, the illumination areas 110c and 210c are indicated by diagonal hatching.
  • the positional relationship between the line sensor cameras 106 and 108 and the semi-annular screen is shown in FIG. 11(a).
  • the line sensor cameras 106 and 108 are placed outside the semi-annular screen 105b.
  • the circumferential viewing range 111 of the line sensor cameras 106 and 108 is at least 180° from 0° to (90°) to 180° of the semi-annular screen 105b in FIG. Covers a range of minutes.
  • observation optical axes 12a and 12b of line sensor camera 106 and line sensor camera 108 are set to intersect with semi-annular screen 105b at positions of 45° and 135°, respectively, as in the first embodiment.
  • FIG. 11(b) shows the positional relationship between the line sensor cameras 206 and 208 and the semi-annular screen 205b.
  • the positional relationship between the line sensor cameras 206 and 208 and the semi-annular screen 205b and the circumferential visual field range 211 of the line sensor cameras 206 and 208 are determined by the relationship between the line sensor cameras 106 and 108 and the semi-annular screen 105b.
  • the angles of the observation optical axes 22a and 22b of the line sensor cameras 206 and 208 are also the same as the relationship between the line sensor cameras 106 and 108 and the semi-annular screen 105b.
  • the sphere 100 is irradiated with the toric semi-annular beams 10c and 20c, and the reflected light from the spherical surface is projected onto the semi-annular screens 105b and 205b. Accordingly, by observing the surfaces of the semi-annular screens 105b and 205b, the entire spherical surface can be inspected in addition to the effect of the first embodiment.
  • FIG. 12 is a plan view showing a surface inspection apparatus 2' which is a modification of this embodiment.
  • the optical axis 10 a and the optical axis 20 a of the surface inspection device 2 ′ are coaxial and pass through the center O of the sphere 100 .
  • the laser oscillator 101 and the laser oscillator 201 are located on opposite sides of the sphere 100 with the center O therebetween.
  • FIG. 13 is an enlarged perspective view for explaining a state in which the spherical surface of the sphere 100 is irradiated with the semi-annular beams 10c and 20c.
  • the illumination areas 110c and 210c of the semi-annular beams 10c and 20c applied to the spherical surface of the sphere 100 are indicated by hatching.
  • the semi-annular beams 10c and 20c irradiate the same side of the plane formed by the optical axis 10a and the rotation axis 11b.
  • This structure creates a space on the opposite side of the semi-annular screen 105c across the optical axis 10a, making it easier to transport the sphere 100 to the inspection area.
  • a light irradiation device 60 different from the light irradiation device 50 emits an annular beam 20b different from the annular beam 10b so as to form a circle around the optical axis 20a of the annular beam 20b.
  • the shaped annular beam 20b is projected onto a spherical surface so that the optical axis 20a passes through the center of the spherical surface. and projecting onto the concave illuminated surface of 205b.
  • the surface inspection apparatuses 2 and 2' of the second embodiment include a light generator 201 that generates the annular beam 20b, an optical device 61 that shapes the ring beam 20b into a circle around the center 20a and irradiates the ring beam 20b that has been shaped into a circle onto the spherical surface so that the optical axis 20a of the ring beam 20b passes through the center of the spherical surface; , provided.
  • Example 3 In the first embodiment, a surface inspection apparatus has been described that can inspect spherical surfaces with substantially the same sensitivity and can inspect with the same inspection apparatus even if the diameter of the sphere to be inspected changes. However, in Example 1, the inspection area is limited to a part of the entire spherical surface. Further, in the second embodiment and its modification, the apparatus capable of inspecting the entire spherical surface of the sphere 100 by combining two optical systems for irradiating the annular beam has been described. However, in Example 2 and its modified example, two optical systems are required, which increases the size of the device.
  • FIG. 14 is a side view of the surface inspection device 3.
  • the light irradiation device 70 has an optical device 71 having an axicon lens 301 arranged between the axicon lens 104 and the sphere 100 of the surface inspection device of the first embodiment.
  • the axicon lens 301 has the same shape and the same material as the axicon lenses 103 and 104 of the first embodiment. It is also assumed that the axicon lens 301 can be moved in the Y-axis direction by a moving mechanism (not shown).
  • the cone axis of the axicon lens 301 coincides with the optical axis 10a and the apex of the cone points toward the sphere 100.
  • FIG. the annular beam 10b passing through the ridge of the cone of the axicon lens 301 is refracted in the direction toward the optical axis 10a, and the outer diameter dr of the axicon lens 103 is proportional to the optical path length centered on the optical axis 10a. and become smaller.
  • FIG. 15 is an enlarged view showing the illumination state of the sphere 100.
  • FIG. FIG. 15 shows only the light 10d' that hits the outer ring of the annular beam 10b after passing through the axicon lens 301.
  • the angle between the light 10d' and the optical axis 10a is ⁇ . That is, the incident angle of the light 10d' with respect to the spherical surface of the sphere 100 is 45°- ⁇ .
  • the distance a between the axicon lenses and the axicon lens 301 are moved to appropriate positions, and the light 10d′ illuminates a point A1 located at a position shifted by 45° ⁇ from the vertex T of the sphere 100, the reflection from the point A1 Light is reflected in a direction perpendicular to the optical axis 10a. Thereby, the reflected light is projected onto the point A1' on the annular screen 105 without interfering with the rotating shaft 11.
  • the inspection area can be expanded as compared with the case of the first embodiment. can.
  • the surface inspection apparatus 3 of the third embodiment can expand the inspection area without increasing the size of the apparatus.
  • the outer diameter of the annular beam 10b is reduced in proportion to the optical path length, and the angle formed by the annular beam 10d and the optical axis 10a is ⁇ (where 0° ⁇ 45° ), where r is the radius of a sphere having a spherical surface, the circular beam 10d is projected onto the sphere 100 so that the outer diameter of the circular light is 2r ⁇ cos (45° ⁇ ). to mold.
  • the optical device 71 includes an axicon lens 301 that reduces the outer diameter of the annular beam 10b in proportion to the optical path length.
  • Example 4 A surface inspection apparatus 4 of Example 4 will be described with reference to FIG.
  • the annular screen 105 is curved and has blind spots
  • two line sensor cameras are used to observe the optical image on the annular screen 105 .
  • an optical image projected onto the annular screen 105 is detected by one line sensor camera without blind spots.
  • the surface inspection apparatus 4 replaces the annular screen 105 of the surface inspection apparatus 1 of the first embodiment with a screen (hereinafter referred to as an arc screen in this embodiment) 105d having an arcuate band-shaped surface to be irradiated.
  • FIG. 17 is a front view of the surface inspection apparatus 4 viewed from the laser oscillator 101.
  • FIG. The arcuate screen 105d is a part of an arc having a sufficiently large radius L0' and is concave on the optical axis 10a side.
  • the center point Od of the arc screen 105d is farther from the line sensor camera 106 than the center point O of the sphere 100, and O and Od are separated by L0'-u1.
  • the light reflected from points A and B on the spherical surface of the sphere 100 becomes reflected light parallel to the rotation axis 11, and points A1' and B1' are projected onto the arcuate screen 105d. If the reflected light from the arc AB can be observed, when the sphere 100 is rotated around the rotation axis 11, the area symmetrical about the rotation axis 11 can also be observed, so the entire area of the illumination area 110 can be inspected. The reflected light from the arc AB is projected onto the illumination area of the arc A'B' on the arc screen 105d.
  • Example 5 a surface inspection apparatus 5 capable of performing inspection at the same magnification even when the radius r of the sphere 100 changes will be described with reference to FIG. 18 .
  • the reflected light from the sphere 100 is magnified in the rotation axis direction and the rotation direction of the sphere 100 and projected onto the annular screen.
  • the rotation axis direction of the sphere 100 can be obtained from the distance L0 between the annular screen and the optical axis 10a and the radius r of the sphere 100 from equation (8).
  • M_XZ 1.414 ⁇ L0/r (8)
  • the screen is a truncated cone screen 105e having a hollow truncated cone-shaped and strip-shaped irradiated surface, and the cone axis of the truncated cone screen 105e coincides with the optical axis 10a.
  • the truncated cone screen 105e has a configuration that is movable in the Y-axis direction (optical axis 10a direction). With this structure, even if the radius r of the sphere 100 changes, the distance L0 to the projection surface of the truncated cone screen 105e can be adjusted by moving the truncated cone screen 105e in the Y-axis direction (optical axis direction).
  • the magnification M_XZ in the rotation axis direction of the optical image projected onto 105e can be made constant. Further, in the surface inspection apparatus 5, the holding device 401 for the sphere 100 is configured to be able to be inserted into the hollow of the truncated cone screen 105e from the direction opposite to the irradiation direction of the annular beam 10b.
  • the surface inspection apparatus 5 can inspect the surface of the sphere 100 at the same magnification regardless of the radius r of the sphere 100, in addition to the effect of the first embodiment.
  • the truncated cone screen 105e of the surface inspection apparatus 5 of the fifth embodiment has a hollow truncated cone shape, and is moved in the direction of the optical axis 10a so that the distance from the optical axis 10a to the projection surface of the truncated cone screen 105e is variable. have possible configurations.
  • the holding device 115 of Example 1 is configured to rotate the sphere 100 .
  • the inspection object of the present invention is not limited to the spherical body 100, and is not limited to a spherical body as long as it is a member having a spherical surface.
  • a piston with a spherical surface may be the specimen object.
  • FIG. 19 is a diagram showing the configuration of a holding device 615 of the surface inspection apparatus of Example 6. As shown in FIG. The retaining device 615 of Example 6 can rotatably retain the piston 100b.
  • the piston 100b has a shape in which a spherical portion 100c having a spherical surface is integrally formed with a tapered body portion.
  • the surface inspection apparatus 1 can use the piston 100b as an inspection target and the spherical portion 100c as an inspection target. That is, the light irradiation device 50 can be configured to irradiate the spherical portion 100c of the piston 100b with an annular beam.
  • the retainer 615 mounts the piston 100b to a rotatable retainer 617 that includes a rotating mechanism.
  • the line sensor camera 108 and the lens 109 are arranged so that the observation optical axis 12b forms an angle of 45° with respect to the annular screen 105.
  • FIG. Also, the line sensor camera 106 and the lens 107 are arranged so that the observation optical axis 12 a forms an angle of 45° with respect to the annular screen 105 .
  • the holding device 615 has a swinging mechanism (for example, a goniometer stage in this embodiment) 618 that can swing.
  • the rotating mechanism (for example, rotating stage) of the retainer 617 and the goniometer stage of the rocking mechanism 618 are integrally formed.
  • the surface inspection apparatus 7 of Example 7 has a light irradiation device 80 that irradiates the sphere 100 with circularly shaped light.
  • the surface inspection apparatus 7 of Example 7 will be described with reference to FIG. Unlike the first embodiment in which the sphere 100 is irradiated with the annular ring beam 10b, in this embodiment, the light irradiated onto the sphere 100 is circular light shaped to be circular.
  • the surface inspection device 7 includes a light generator (laser oscillator) 101, an optical device 702 consisting only of a beam expander, an annular screen 105, a line sensor camera 106, a lens 107, a line sensor camera 108, a lens 109.
  • the optical device 702 does not have the axicon lenses 103 and 104 shown in the first embodiment.
  • the optical device 702 is a beam expander (optical system) that expands or reduces the beam diameter.
  • Optical device 702 may be a Keplerian beam expander or a Galilean beam expander.
  • the optical device 702 of Example 6 has an objective lens 702a and an image side lens 702b. Parallel light incident on the objective lens 702a is condensed at a focal point between the objective lens 702a and the image side lens 702b, and the diameter of the circular light increases as the irradiation distance from the objective lens 702a increases.
  • the circular light incident on the image-side lens 702b becomes circular light 10e that is parallel to the optical axis 10a and circular again after passing through the image-side lens 702b.
  • the optical axis 10a of the circular light 10e passes through the center O of the spherical surface.
  • the sphere 100 By making the light emitted to the sphere 100 circular as in the present embodiment, it is possible to inspect the surface of the sphere 100 in the same manner as in the case of irradiating circular light. Further, for example, when performing surface inspection using circular light as in Example 7, or when irradiating the sphere 100 with light from a plurality of positions as in the various examples described above, the sphere 100 Rotating the sphere 100 may not be necessary in some cases, such as when only a portion is to be inspected. The same applies to the swing mechanism 618 as well. That is, the holding devices 115, 401 and 615 do not need to have the rotating mechanism 117 or the swinging mechanism 618, and may be configured to hold the inspection object at a predetermined position.
  • the present invention is not limited to the above-described embodiments, and includes various modifications.
  • the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations.
  • it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment and it is also possible to add the configuration of another embodiment to the configuration of one embodiment.

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PCT/JP2022/045211 2021-12-14 2022-12-08 表面検査方法および表面検査装置 WO2023112809A1 (ja)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4963459A (enrdf_load_stackoverflow) * 1972-10-16 1974-06-19
US4398825A (en) * 1981-02-17 1983-08-16 General Motors Corporation Optical scanner for ball inspection
JPS58219441A (ja) * 1982-06-15 1983-12-20 Hajime Sangyo Kk 凸面体の表面欠陥検査装置
JPH0470555A (ja) * 1990-07-11 1992-03-05 Sumitomo Metal Ind Ltd 球体表面検査装置
CN112284984A (zh) * 2020-10-19 2021-01-29 陕西科技大学 一种基于光反射的固体表面能测定装置及方法
KR102274955B1 (ko) * 2021-02-02 2021-07-08 주식회사 아이엘비 비전 촬영에 의한 야구공 둘레 자동 측정시스템

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4963459A (enrdf_load_stackoverflow) * 1972-10-16 1974-06-19
US4398825A (en) * 1981-02-17 1983-08-16 General Motors Corporation Optical scanner for ball inspection
JPS58219441A (ja) * 1982-06-15 1983-12-20 Hajime Sangyo Kk 凸面体の表面欠陥検査装置
JPH0470555A (ja) * 1990-07-11 1992-03-05 Sumitomo Metal Ind Ltd 球体表面検査装置
CN112284984A (zh) * 2020-10-19 2021-01-29 陕西科技大学 一种基于光反射的固体表面能测定装置及方法
KR102274955B1 (ko) * 2021-02-02 2021-07-08 주식회사 아이엘비 비전 촬영에 의한 야구공 둘레 자동 측정시스템

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