JP7222575B1 - Cylindrical inner surface inspection device - Google Patents

Abstract

An object of the present invention is to provide a cylindrical inner surface inspection device that can improve both the accuracy of detecting minute abnormalities and the accuracy of detecting abnormalities on rough surfaces. [Solution] A laser emitting device that generates a plurality of laser beams with different center wavelengths to irradiate the inner surface of a cylindrical inspection object, and a tip portion that uses the plurality of laser beams from the laser emitting device as irradiation light. It is equipped with an inspection probe that transmits the irradiation light from the tip to the inner surface of the object to be inspected, and transmits the reflected light from the inner surface of the object to the rear end. a scanning unit that sequentially irradiates the entire circumference of the inner surface of the object to be inspected; a photoelectric conversion unit that converts reflected light emitted from the rear end of the inspection probe into electrical signals for each wavelength; a laser emitting device; a scanning unit; and a moving device that moves the main body including the photoelectric conversion section. [Selection diagram] Figure 3

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical inner surface inspection apparatus for inspecting the inner surface of a cylindrical object to be inspected for flaws and the like.

2. Description of the Related Art Cylindrical members and parts with cylindrical holes are used in various products such as automobiles and electric appliances. If there are scratches, foreign matter, or dirt on the inner surface of the cylinder of these members and parts, problems will occur in the performance and quality of the product. A method and inspection apparatus have been proposed.

For example, in order to inspect the presence or absence of scratches on the inner surface of automobile engine cylinders, brake master cylinders, etc., inspection methods such as photographing with a device such as a camera from the outside of a cylindrical hole, optical elements, etc. An inspection method has been proposed in which a cylindrical inspection probe attached to the tip is inserted into a cylindrical hole and the inner surface is inspected using a camera or laser light.

Among these various inspection methods, in order to enable high-speed inspection of the inner surface of a small-diameter hole, a laser beam is irradiated onto the inner surface of the hole to be inspected, and the intensity of the reflected light is measured. proposed a method for inspecting the presence or absence of flaws on the inner surface of a hole to be inspected. (See Patent Documents 1 and 2, for example).

In Patent Document 1, a laser beam is irradiated onto the surface of an object to be inspected through a light guiding space in a rotary cylinder that is rotatably mounted on a main body having a laser oscillator, and the laser beam reflected from the surface of the object to be inspected is rotated. A surface inspection device is disclosed that is configured to transmit to a determination processing device on the main body side via a plurality of optical fibers arranged in a cylinder. In this surface inspection apparatus, the presence or absence of flaws or the like on the inner surface of the cylinder to be inspected is determined by detecting changes in the intensity of the reflected laser beam.

Further, in Patent Document 2, a pipe-shaped member such as a cylindrical glass pipe is provided in an inspection probe, and a laser beam is transmitted to the tip through a hollow region of the pipe-shaped member. The inner surface of the object to be inspected is irradiated with the irradiation light by being reflected by the reflecting member, and the reflected light reflected from the inner surface of the object to be inspected is reflected by the reflecting member and passes through the area other than the hollow area of the pipe-shaped member. A transmitting cylindrical inner surface inspection apparatus is disclosed.

In addition, in Patent Document 3, an optical element having a reflection or refraction angle in the 360-degree direction is provided at the tip of the inspection probe, and the laser light is emitted in the 360-degree direction by sequentially irradiating while adjusting the irradiation angle of the laser light. A cylindrical inner surface inspection apparatus is disclosed that inspects the inner surface of a cylindrical inspection object without rotating the inspection probe when scanning the inner surface of the cylindrical inspection object.

Japanese Patent No. 5265290 Japanese Patent No. 6675749 Japanese Patent No. 7049726

In the inspection apparatus as described above, the smaller the spot diameter of the laser beam when the inner surface of the object to be inspected is irradiated with the laser beam, the more minute abnormalities such as scratches and irregularities can be detected. However, if the spot diameter of the laser beam is made small, the intensity of the reflected light will change sensitively even if there is a cut mark on the inner surface of the inspection object (rough surface, not an abnormal location), making it difficult to distinguish the abnormal location. There's a problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cylindrical inner surface inspection apparatus capable of improving the detection accuracy of minute abnormal points and improving the detection accuracy of abnormal points on rough surfaces.

A cylindrical inner surface inspection apparatus according to the present invention comprises a laser light emitting device for generating a plurality of laser beams having different central wavelengths for irradiating the inner surface of a cylindrical inspection object, and the plurality of laser beams emitted from the laser light emitting device. Equipped with an inspection probe that transmits light as irradiation light to the front end, irradiates the inner surface of the inspection object with the irradiation light from the front end, and transmits the reflected light reflected from the inner surface of the inspection object to the rear end, and irradiates A scanning unit that sequentially irradiates light from the tip of the inspection probe to the entire periphery of the inner surface of the inspection object, and a photoelectric conversion unit that converts the reflected light emitted from the rear end of the inspection probe into an electrical signal for each wavelength. and a moving device that moves a main body including the laser light emitting device, the scanning section, and the photoelectric conversion section.

According to another cylindrical inner surface inspection apparatus of the present invention, center wavelengths of the plurality of laser beams may be set to differ from each other by 100 nm or more.

Further, according to another cylindrical inner surface inspection apparatus of the present invention, the center wavelengths of the plurality of laser beams are ultraviolet light with a wavelength band of 280 nm or more and less than 380 nm, violet light with a wavelength band of 380 nm or more and less than 430 nm, and blue light with a wavelength band of 430 nm or more and less than 490 nm. Light, green light of 490 nm or more and less than 550 nm, yellow light of 550 nm or more and less than 590 nm, orange light of 590 nm or more and less than 640 nm, red light of 640 nm or more and less than 770 nm, near infrared light of 770 nm or more and less than 2500 nm, infrared light of 2500 nm or more may be set so as to be a combination of classifications different from each other.

Further, according to another cylindrical inner surface inspection apparatus of the present invention, the spot diameters of the plurality of laser beams irradiated onto the inner surface of the inspection object may be different from each other by 25 μm or more.

Further, according to another cylindrical inner surface inspection apparatus of the present invention, the scanning unit irradiates the inner surface of the inspection object with a plurality of laser beams having center wavelengths different from each other, and the spot diameter of the spot light is changed for each center wavelength. A plurality of spot lights having different diameters and having different spot diameters may be concentrically superimposed such that the central positions of the spot lights are at the same position, and the inner surface of the inspection object may be simultaneously irradiated with the plurality of spot lights. good.

Further, according to another cylindrical inner surface inspection apparatus of the present invention, the scanning unit includes a pipe-shaped member made of a transparent material that transmits laser light from the laser light emitting device as irradiation light through a hollow region; It is composed of a cylindrical exterior member that accommodates the pipe-shaped member inside, and a reflecting member provided at the tip of the exterior member. The irradiation light is transmitted and reflected by the reflecting member provided at the tip, so that the inner surface of the inspection object is irradiated with the irradiation light, and the reflected light reflected from the inner surface of the inspection object is reflected by the reflecting member. The inspection probe may be transmitted through a region other than the hollow region of the pipe-shaped member, and a rotating device for rotating the inspection probe.

Further, according to another cylindrical inner surface inspection apparatus of the present invention, the scanning unit includes an irradiation angle adjustment unit that adjusts the irradiation angle of the laser light generated in the laser light emitting device, and an irradiation angle adjustment unit that adjusts the reflection or refraction angle in 360-degree directions. A deflection optical element is provided at the tip, and the laser beam whose irradiation angle has been adjusted by the irradiation angle adjustment unit is transmitted to the tip where the laser beam is inserted into the inside of the inspection object, and the deflection optical element By reflecting or refracting, the entire perimeter of the inner surface of the inspection object is sequentially irradiated as irradiation light, and the reflected light reflected from the inner surface of the inspection object is reflected or refracted by the deflection optical element. and the inspection probe transmitting to the opposite end face.

According to the cylindrical inner surface inspection apparatus of the present invention, it is possible to provide a cylindrical inner surface inspection apparatus capable of improving the detection accuracy of minute abnormal points and improving the detection accuracy of abnormal points on rough surfaces. .

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view for demonstrating schematic structure of the cylindrical inner surface inspection apparatus 10 of one Embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the external appearance at the time of seeing the cylindrical inner surface inspection apparatus 10 of one Embodiment of this invention from side. FIG. 3 is a diagram for explaining the details of the configuration of a body portion 11 shown in FIG. 2; FIG. 4 is a diagram for explaining the configuration of an irradiation angle adjustment unit 18 shown in FIG. 3; FIG. 4 is a perspective view of the optical element 30 shown in FIG. 3. FIG. 8 is a diagram for explaining how the inspection probe 12 is moved up and down within the hole of the inspection object 80 by the lifting device 14. FIG. FIG. 7A shows reflected light/scattered light when there is no abnormality such as a scratch on the inspection target surface of the inspection object 80 (FIG. 7A), and reflected light/scattered light when there is an abnormality such as a scratch. is a diagram (FIG. 7(B)) showing a state of . FIG. 4 is a diagram for explaining the structure of an inspection probe 12 shown in FIGS. 2, 3, etc. FIG. 3 is a cross-sectional view of an inspection probe 12 and a photoelectric conversion unit 17; FIG. FIG. 10A shows how a flaw is detected using a visible laser beam, and FIG. 10B shows how a flaw is detected using a near-infrared laser beam. A diagram showing the state of the surface roughness component when detection is performed with a visible laser beam (FIG. 11 (A)), and the surface roughness component when detection is performed with a near-infrared laser beam. It is a figure (FIG. 11(B)) which shows a state. It is a schematic diagram in the case of performing an inspection with two laser beams of visible light and near-infrared light. It is a figure for demonstrating the detail of a structure of the main-body part 111 of a modification.

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view for explaining a schematic configuration of a cylindrical inner surface inspection apparatus 10 according to one embodiment of the present invention.

A cylindrical inner surface inspection apparatus 10 of the present embodiment is an apparatus for inspecting the state of the inner surface (or inner surface) of a cylindrical object such as an inspection object 80, for example. In the cylindrical inner surface inspection apparatus 10 , when inspecting the state of the inner surface of the inspection object 80 , the inspection probe 12 is inserted into the inspection object hole of the inspection object 80 . By moving the inspection probe 12 up and down while rotating at high speed, the entire inner surface of the inspection object 80 is scanned and inspected.

A terminal device 20 such as a personal computer is connected to the cylindrical inner surface inspection apparatus 10 of the present embodiment, and processes such as control of the operation of the cylindrical inner surface inspection apparatus 10 and display of inspection results are performed. Here, the terminal device 20 is an example of a device that controls the cylindrical inner surface inspection device 10, and various devices such as a smartphone and a tablet terminal are connected to the cylindrical inner surface inspection device 10 via a wireless line, and the cylindrical inner surface inspection device 10 is connected. It is also possible to perform processing such as control of the operation of , display of inspection results, and the like. Furthermore, it is also possible to integrate a control section for controlling the operation of the cylindrical inner surface inspection apparatus 10, a display section for displaying inspection results, and the like with the cylindrical inner surface inspection apparatus 10. FIG.

Next, FIG. 2 shows the external appearance of the cylindrical inner surface inspection apparatus 10 of this embodiment when viewed from the side. As shown in FIG. 2, the cylindrical inner surface inspection apparatus 10 of this embodiment is composed of a main body 11, an inspection probe 12, an arm 13, an elevating device 14, a column 15, and a pedestal 19. .

The strut 15 is vertically supported on the pedestal 19 . An elevating device 14 is attached to the column 15 , and the elevating device 14 is configured to move vertically along the column 15 . An arm 13 is provided in the horizontal direction from the lifting device 14, and the body portion 11 is attached to the tip of the arm 13. As shown in FIG.

An inspection probe 12 that rotates at high speed during inspection is attached to the main body 11 . The inspection probe 12 rotates at a high speed of 1000 rpm or more, for example 2000-4000 rpm.

An opening for emitting laser light is provided at the tip of the inspection probe 12, and the laser light scans the inner surface of the inspection object 80 as irradiation light.

Further, the terminal device 20 includes a control section 21 , a processing section 22 and a display section 23 . The control unit 21 controls the operation of the lifting device 14 and the main unit 11 of the cylindrical inner surface inspection apparatus 10 . The processing unit 22 receives the intensity signal of the reflected light output from the main unit 11 and performs determination processing for determining whether or not the inner surface of the inspection object 80 has a scratch or the like. The display unit 23 displays the determination result of the processing unit 22 .

The processing unit 22 monitors an increase or decrease in the intensity of the reflected light from the inner surface of the inspection object 80. For example, when the intensity of the reflected light increases or decreases by a preset value or more, the inspection object 80 It is determined that there is a scratch or foreign matter adhered to the inner surface of the Here, the processing unit 22 does not monitor the value of the received light intensity of the reflected light itself, but also determines the presence or absence of a flaw or the like using the continuity of the received light intensity during the inspection as a determination criterion.

Next, the configuration of the main body portion 11 shown in FIG. 2 will be described in detail with reference to FIG.

As shown in FIG. 3, the main body 11 includes a laser light emitting device 16, a photoelectric conversion section 17, and a hollow motor 18 in addition to the inspection probe 12. As shown in FIG.

The laser light emitting device 16 generates a plurality of laser beams with different central wavelengths for irradiating the inner surface of the cylindrical inspection object.

There are no particular restrictions on the number of laser beams generated by the laser light emitting device 16 and the center wavelength of each laser beam. However, it is preferable to set the central wavelengths of the plurality of laser beams so as to differ from each other by 100 nm or more. Further, it is preferable that the central wavelength of the laser beam having the longest central wavelength among the plurality of laser beams is a wavelength in the near-infrared band of 770 nm or more and less than 2500 nm. In addition, it is preferable that the center wavelength of the laser light having the shortest center wavelength among the plurality of laser lights is a wavelength in the visible light band of 380 nm or more and less than 770 nm.

Here, the center wavelength of the laser light is defined by the peak wavelength of the spectral characteristics of the laser light or the center wavelength of the full width at half maximum of the spectral characteristics.

In this embodiment, as an example, the laser light emitting device 16 generates two types of laser light, a laser light L1 having a center wavelength of 630 nm and a laser light L2 having a center wavelength of 820 nm.

As shown in FIG. 2, the laser light emitting device 16 is not limited to one that generates a plurality of laser beams inside a single device and multiplexes and outputs the generated laser beams. A plurality of laser light emitting devices may be provided for each wavelength, and laser light emitted from each of the plurality of laser light emitting devices may be combined by a light combining optical element such as a dichroic mirror or prism.

The hollow motor 18 is a motor whose rotating shaft has a hollow structure, and is a rotating device that rotates the inspection probe 12 by inserting the inspection probe 12 into this hollow portion. In this embodiment, the inspection probe 12 and the hollow motor 18 constitute the scanning section in the technology of the present invention.

In this embodiment, a structure in which the inspection probe 12 is rotated by the hollow motor 18 will be described, but the rotating device is not limited to such a structure. It is also possible to use a rotating device configured to rotate the inspection probe 12 by transmitting a rotational force to the inspection probe 12 .

The photoelectric conversion section 17 converts the reflected light emitted from the rear end portion of the inspection probe 12 into an electric signal for each wavelength. An electrical signal indicating the intensity of the reflected light converted by the photoelectric conversion section 17 is transferred to the processing section 22 of the terminal device 20 .

A main body 11 composed of a laser light emitting device 16, an inspection probe 12, a hollow motor 18, and a photoelectric conversion section 17 is connected to an elevating device 14 by an arm 13, and is moved up and down by the elevating device 14. It's becoming

In the present embodiment, a configuration in which inspection is performed by moving the main body 11 up and down by the lifting device 14 will be described. is also possible. Further, when the hole to be inspected is horizontal, the apparatus may be used in a laid down state, and in such a case, the main body 11 is moved horizontally. In other words, the lifting device 14 may function as a moving device for moving the main body 11 .

Further, as shown in FIG. 3, the laser light generated by the laser light emitting device 16 passes through the photoelectric conversion section 17 as the irradiation light 101, passes through the hollow region in the inspection probe 12, and passes through the inspection probe 12. The light reaches the tip and is reflected at the tip to change the direction and irradiate the inner surface of the inspection object 80 . The reflected light 102 reflected by the inner surface of the inspection object 80 is transmitted through the inspection probe 12 and reaches the photoelectric conversion section 17 . Detailed structures of the inspection probe 12 and the photoelectric conversion section 17 will be described later.

Next, with reference to FIGS. 4 and 5, a description will be given of how the inner surface of the inspection object 80 is inspected by the cylindrical inner surface inspection apparatus 10 of the present embodiment.

When inspecting the inner surface of the inspection object 80, the inspection probe 12 is rotated at high speed and moved up and down in the hole of the inspection object 80 by the lifting device 14, as shown in FIG. Therefore, the irradiation light 101 from the inspection probe 12 scans the entire inner surface of the inspection object 80 .

Next, the state of the reflected light/scattered light when there is no abnormality such as a scratch on the inner surface of the inspection object 80, that is, the surface to be inspected, and the state of the reflected light/scattered light when there is an abnormality such as a scratch are shown. It is shown in FIGS. 5A and 5B.

Referring to FIG. 5A, when there is no abnormality such as a scratch on the inspection target surface of the inspection object 80, the irradiation light 101 is uniformly reflected or scattered at the irradiation point. I understand. On the other hand, referring to FIG. 5B, when there is an abnormality such as a scratch on the inspection target surface of the inspection object 80, the irradiation light 101 is not uniformly reflected or scattered at the irradiation point, and a specific It can be seen that the light is reflected or scattered in directions.

That is, when the inspection target surface of the inspection object 80 is scanned with the irradiation light 101, the intensity of the reflected light changes at a location where there is an abnormality such as a scratch. Therefore, the processing unit 22 detects this change and determines that there is some abnormality in the inspection surface of the inspection object 80 .

Next, the structure of the inspection probe 12 shown in FIGS. 2, 3, etc. will be described.

As shown in FIG. 6, the inspection probe 12 in this embodiment has a cylindrical hollow glass pipe 61 made of quartz glass (silica glass) inserted into a cylindrical exterior member 62 made of stainless steel or the like. It is configured by

Here, quartz glass is glass that contains almost no impurities and is composed of almost 100% SiO ₂ (silicon dioxide). This quartz glass has characteristics of extremely high transparency and very high light transmittance as compared with general glass. In addition, quartz glass has characteristics that it is superior to general glass in terms of heat resistance and chemical resistance.

Since the glass pipe 61 is made of quartz glass having such characteristics, the transmission rate of the reflected light 102 is higher than that of a glass pipe made of general glass.

An opening 63 for emitting the irradiation light 101 and for entering the reflected light 102 is provided at the tip of the exterior member 62 .

Next, FIG. 7 shows a cross-sectional view of the inspection probe 12 and the photoelectric conversion section 17 having such a structure. Note that FIG. 7 is a diagram for explaining the schematic configuration of the device configuration, so the vertical dimension is omitted for brevity.

The glass pipe 61 transmits laser light from the laser light emitting device 16 as irradiation light 101 to the tip through the hollow region. The exterior member 62 accommodates the glass pipe 61 inside, as described with reference to FIG. The glass pipe 61 is fixed to the exterior member 62 by being adhered to the exterior member 62, and when the exterior member 62 is rotated at high speed by the hollow motor 18, the glass pipe 61 rotates at high speed along with this rotation. .

A reflecting mirror 64, which is a reflecting member, is attached to the tip of the exterior member 62 at an angle of 45 degrees with respect to the horizontal direction. Therefore, the reflecting mirror 64 reflects the irradiation light 101 passing through the hollow region of the glass pipe 61 to change the traveling direction by 90 degrees. Therefore, the irradiation light 101 is emitted from the opening 63 to irradiate the inner surface of the inspection object 80 .

Here, the case where the installation angle of the reflection mirror 64 is set to 45 degrees and the traveling direction of the irradiation light 101 is changed by 90 degrees is described. In some cases, the traveling direction of the irradiation light 101 is changed to a direction other than 90 degrees.

Further, the reflected light 102 reflected by the inner surface of the inspection object 80 enters the opening 62 and is reflected by the reflecting mirror 64, changing its traveling direction by 90 degrees. Reflected light 102 whose traveling direction is changed by 90 degrees is transmitted to photoelectric conversion section 17 through a region other than the hollow region of glass pipe 61, that is, a region made of silica glass.

With such a configuration, the inspection probe 12 transmits the irradiation light 101 through the hollow region of the glass pipe 61 to the tip and reflects it by the reflecting mirror 64 provided at the tip. The inner surface of the inspection object 80 is irradiated with irradiation light 101, and the reflected light 102 reflected from the inner surface of the inspection object 80 is reflected by the reflecting mirror 64, and passes through the area other than the hollow area of the glass pipe 61 to the photoelectric conversion unit. 17.

The photoelectric conversion unit 17 is provided with a hole through which the laser beam from the laser light emitting device 16 passes, and a separation optical element 72 and photoelectric conversion sensors 73a and 73b are mounted around the hole. It is composed of a perforated substrate 71, which is a substrate-like member arranged so that the end surface of the glass pipe on the side opposite to the tip of the inspection probe is close to the end surface of the glass pipe.

Next, the perforated substrate 71 shown in FIG. 7 will be described in detail with reference to FIG.

As shown in FIG. 8, the perforated substrate 71 is provided with a laser beam passage hole 71a in the center, and a separation optical element 72 and photoelectric conversion sensors 73a and 73b are provided on the left and right sides of the laser beam passage hole 71a, respectively. are distributed.

The separating optical element 72 is composed of a dichroic mirror, a prism, or the like. The photoelectric conversion sensors 73a and 73b are small light-receiving elements composed of photodiodes, CMOS sensors, or the like, and are configured as chip parts.

The reflected light 102 composed of the reflected light of the laser light L1 with a center wavelength of 630 nm and the reflected light of the laser light L2 with a center wavelength of 820 nm is separated by the optical element 72 for separation into the reflected light of the laser light L1 and the reflected light of the laser light L2. separated into The reflected light of the separated laser light L1 enters the photoelectric conversion sensor 73a, and the reflected light of the separated laser light L2 enters the photoelectric conversion sensor 73b.

As a result, the reflected light of the laser light L1 having a center wavelength of 630 nm and the reflected light of the laser light L2 having a center wavelength of 820 nm can be separately detected while configuring the photoelectric conversion unit 17 in a small size.

Note that the photoelectric conversion unit 17 is not limited to the configuration in which the separation optical element 72 and the photoelectric conversion sensors 73a and 73b are attached to the perforated substrate 71 as described above, and may be configured in another configuration. FIG. 9 shows an example of a photoelectric conversion unit having another structure as a photoelectric conversion unit 117. In FIG.

The photoelectric conversion unit 117 shown in FIG. 9 includes a perforated mirror 74, a condenser lens 75, a separating optical element 76, and photoelectric conversion sensors 77a and 77b. In the photoelectric conversion unit 117, the photoelectric conversion sensors 77a and 77b are configured as parts larger than the chip parts, and after the reflected light emitted from the glass pipe 61 is reflected by the perforated mirror 74, it is After condensing, the light is made incident on the separation optical element 76, and is received by photoelectric conversion sensors 77a and 77b for each wavelength.

In such a mode, the photoelectric conversion sensors 77a and 77b can be sized and arranged more freely.

Next, the operation of the cylindrical inner surface inspection apparatus 10 of this embodiment will be described.

In the cylindrical inner surface inspection apparatus 10, the surface of the object to be inspected is irradiated with laser light, and the photoelectric conversion sensors 73a and 73b receive the reflected light corresponding to the spot diameter size of the laser light for each detection unit. The received light intensity detected by 73b is converted into data. In addition, the cylindrical inner surface inspection apparatus 10 scans the surface of the object to be inspected with a laser beam, and continuously converts the received light intensity detected by the photoelectric conversion sensors 73a and 73b into data. At this time, the smaller the spot diameter of the laser beam, the more minute abnormalities such as scratches and irregularities can be detected.

Specifically, as shown in FIG. 10A, when the spot diameter of the laser beam is small relative to the abnormal portion such as a scratch or unevenness, the ratio of the area of the abnormal portion to the spot diameter is large. Since the change in the intensity of the reflected light is large, when the inner surface of the object to be inspected is imaged based on the intensity of the reflected light, abnormal points are clearly displayed.

On the other hand, as shown in FIG. 10B, when the spot diameter of the laser beam is large relative to the abnormal portion such as a scratch or unevenness, the ratio of the abnormal portion to the spot diameter is small, and the portion with the abnormal portion The intensity change of the reflected light of the part and the intensity change of the reflected light of the part without the abnormal part are averaged, and the intensity change of the reflected light due to the presence or absence of the abnormal part becomes small. When imaging the inner surface of the

On the other hand, when the spot diameter of the laser beam is reduced, the intensity of the reflected light changes sensitively even if there is a cut mark on the inner surface of the inspection object (rough surface, not an abnormal area), so inspection is based on the intensity of the reflected light. When the inner surface of the object is imaged, it becomes difficult to distinguish an abnormal portion.

Specifically, as shown in FIG. 11(A), when the spot diameter of the laser beam is small, the intensity of the reflected light changes greatly even if the unevenness is caused by the accuracy of the surface roughness instead of the abnormal location. As a result, when the inner surface of the object to be inspected is imaged based on the intensity of the reflected light, surface roughness components due to fine irregularities other than scratches (hereinafter referred to as unnecessary surface roughness components) increase. .

On the other hand, as shown in FIG. 11B, when the spot diameter of the laser beam is large, the intensity change of the reflected light due to the irregularities within the spot diameter is averaged, and the intensity change of the reflected light becomes smaller. When the inner surface of the inspection object is imaged based on the intensity of the reflected light, unnecessary surface roughness components are reduced.

As described above, a smaller spot diameter of the laser beam is advantageous for detecting abnormal locations such as scratches and unevenness, and a larger spot diameter of the laser beam is advantageous for reducing unnecessary surface roughness components.

Therefore, in the cylindrical inner surface inspection apparatus 10 of this embodiment, as shown in FIG. are combined with two kinds of laser beams.

The minimum spot diameter w when a laser beam is condensed and irradiated by a lens is expressed by the following formula (1), where λ is the center wavelength of the laser beam and NA is the numerical aperture of the lens. From equation (1), it can be seen that the minimum spot diameter w increases in proportion to the center wavelength of the laser light, provided that the numerical aperture NA of the lens is constant.
w=0.61λ/NA (1)

Strictly speaking, the minimum spot diameter w depends not only on the center wavelength λ of the laser light and the numerical aperture NA of the lens, but also on the beam quality ^M2 of the laser light. The ideal value of the beam quality M ² (M ² ≧1.0) is 1.0, and the minimum spot diameter w increases in proportion to the numerical value of the beam quality M ² . For example, when M ² =1.2, the minimum spot diameter w is 1.2 times larger than when M ² =1.0, assuming that the conditions other than the beam quality M ² are the same.

As an example, in the case of a visible laser beam L1 with a central wavelength of 630 nm, the diameter of the laser beam is 2.0 mm, the focal length at the time of convergence is 500 mm, and the beam quality ^M2 is 1.2. It can be a spot diameter. In the case of the near-infrared laser beam L2 with a central wavelength of 820 nm, the spot diameter can be 0.261014 mm if the conditions other than the central wavelength are the same as those of the laser beam L1.

In the cylindrical inner surface inspection apparatus 10 of the present embodiment, the scanning unit makes the spot diameters of the spot lights when the inner surface of the inspection object 80 is irradiated with the laser beams L1 and L2 different for each center wavelength, and the spot diameter The inner surface of the inspection object 80 is simultaneously irradiated with a plurality of spot lights in a state in which the center positions of the plurality of spot lights differing from each other are concentrically superimposed so as to be at the same position. Further, as described above, the reflected light of the laser beam L1 and the reflected light of the laser beam L2 can be detected separately.

As a result, there are two types of measurement data for the inner surface of the inspection object 80: measurement data in which abnormal points such as fine scratches and irregularities are clearly recorded, and measurement data in which unnecessary surface roughness components are small. can be obtained, and it is possible to determine the location of anomalies by combining two measurement data with different characteristics. becomes possible.

The two measurement data may be used in any manner, and as an example, the following aspects may be used.

First, from the image of the inner surface of the object to be inspected, which is imaged based on the measurement data in which the abnormal portion is clearly recorded, an area having a size equal to or greater than a preset size and a density equal to or greater than a preset density is extracted as an abnormal portion.

Next, the image of the extracted abnormal portion is synthesized at the same position in the image of the inner surface of the inspection object imaged based on the measurement data with few unnecessary surface roughness components, and the unnecessary surface roughness component is eliminated. To acquire an image recognition image in which an abnormal part is displayed while being in a small state.

Based on this image for image recognition, the position, size, etc. of the abnormal portion are specified by software processing.

In addition, in the cylindrical inner surface inspection apparatus 10 of the present embodiment, two laser beams with different spot diameters are used to obtain measurement data in which abnormal points such as scratches and unevenness are clearly recorded, and unnecessary surface roughness components. Since two types of measurement data can be obtained simultaneously in a small amount of measurement data, the measurement time can be shortened compared to a mode in which the two types of measurement data are obtained individually.

For example, it is possible to change the spot diameter by using a single laser beam and changing the focal length with a varifocal lens or the like. Therefore, it is necessary to inspect the same inspection object at least twice before and after changing the spot diameter.

At the production site of products, the inspection time for parts (objects to be inspected) is determined in units of seconds, and the inspection time for parts using a cylindrical inner surface inspection apparatus is required to be as short as one second. Therefore, it is not realistic to inspect the same part multiple times, and it is particularly useful to have a configuration that can simultaneously acquire a plurality of measurement data like the cylindrical inner surface inspection apparatus 10 of this embodiment. is.

In addition, in the cylindrical inner surface inspection apparatus 10 of the present embodiment, a plurality of spot lights are simultaneously applied to the inspection object 80 in a state where the spot lights of the laser lights L1 and L2 having different spot diameters are superimposed so that the central positions of the spot lights are the same. , the laser beams L1 and L2 can measure the same position at the same time. In addition, since the data position of each measurement data and the measurement position of the inspection object 80 are the same in the two measurement data, it is possible to obtain measurement data that can be easily processed for comparison, synthesis, and the like.

Further, in the cylindrical inner surface inspection apparatus 10 of the present embodiment, the two types of laser beams L1 and L2 are combined into one irradiation light 101, and there is only one path for guiding the irradiation light 101 and the reflected light 102. Therefore, the configuration of the inspection probe 12 can be simplified.

Further, as described above, the minimum spot diameter is proportional to the central wavelength of the laser beam, and when the central wavelength is separated by 100 nm, the minimum spot diameter changes by about 25 μm in a general configuration as shown below.

For example, in the case of a laser beam with a central wavelength of 660 nm, the spot diameter is 0.168068 mm if the diameter of the laser beam is 2.0 mm, the focal length at the time of convergence is 400 mm, and the beam quality ^M2 is 1.0. In the case of laser light with a center wavelength of 760 nm, the spot diameter is 0.193532 mm if the conditions other than the center wavelength are the same. Also, the difference between the spot diameters of the two laser beams is 0.025464 mm (approximately 25 μm).

When the difference between the center wavelengths of the two laser beams is less than 100 nm, the difference between the spot diameters of the respective laser beams becomes small, and the difference in the characteristics of the measurement data due to the respective laser beams is less likely to occur.

In the cylindrical inner surface inspection apparatus 10 of the present embodiment, of the two types of laser beams L1 and L2, the center wavelength of the laser beam L1 is set to 630 nm, and the center wavelength of the laser beam L2 is set to 820 nm. They are set to differ by 100 nm or more, so that the minimum spot diameters when the inner surface of the object to be inspected is irradiated with the two laser beams differ by 0.025464 mm, that is, by 25 μm or more.

Therefore, it is possible to acquire two types of measurement data with greatly different characteristics: measurement data in which abnormal points such as fine scratches and unevenness are clearly recorded, and measurement data in which unnecessary surface roughness components are small.

Further, in the cylindrical inner surface inspection apparatus 10 of the present embodiment, the center wavelength of the longer center wavelength of the two types of laser light L1 and L2 is set to the wavelength in the near-infrared light band. As compared with the case of using the wavelength of , it is possible to acquire measurement data with less unnecessary surface roughness components.

In addition, in the cylindrical inner surface inspection apparatus 10 of the present embodiment, the center wavelength of the laser light having the shorter center wavelength of the two types of laser light L1 and L2 is set to the wavelength in the visible light band. Compared to the case of using the wavelength of , it is possible to acquire measurement data in which even minute abnormalities are clearly recorded.

In the above embodiment, the scanning section is composed of the inspection probe 12 and the hollow motor 18, but the scanning section may be composed of the irradiation angle adjusting section 118 and the inspection probe 112 as shown in FIG.

The irradiation angle adjuster 118 in this modified example adjusts the irradiation angle of the laser light generated in the laser light emitting device 116 .

In addition, the inspection probe 112 is provided with a deflection optical element 130 having a reflection or refraction angle in the 360-degree direction at the tip, and the laser beams L1 and L2 after the irradiation angle is adjusted by the irradiation angle adjustment unit 118 are The light is transmitted to the tip inserted into the interior of the inspection object 80 and reflected or refracted by the deflection optical element 130 to sequentially irradiate the inner surface of the inspection object 80 as the irradiation light 101 to the inner surface of the inspection object 80. The reflected light 102 reflected from the tip is reflected or refracted by the deflecting optical element 130 and transmitted to the end face opposite to the tip.

Even if the scanning unit is configured in this way, as in the above embodiment, there are two types of measurement data: measurement data in which abnormal points such as scratches and unevenness are clearly recorded, and measurement data in which unnecessary surface roughness components are small. of measurement data can be obtained simultaneously.

Moreover, since it is not necessary to rotate the inspection probe 112, a hollow motor is not required, and the configuration of the main body 111 can be simplified.

In the above embodiment, the laser light emitting device 16 generates two types of laser light, the visible laser light L1 having a center wavelength of 630 nm and the near-infrared laser light L2 having a center wavelength of 820 nm. However, the number of multiple laser beams generated by the laser light emitting device 16 and the center wavelength of each laser beam may be changed.

For example, the plurality of laser beams are not limited to a combination of visible laser beams and near-infrared laser beams, and may be a combination of visible beams having different center wavelengths.

In addition, the central wavelengths of the plurality of laser beams are ultraviolet light with a wavelength band of 280 nm or more and less than 380 nm, violet light with a wavelength band of 380 nm or more and less than 430 nm, blue light with a wavelength band of 430 nm or more and less than 490 nm, green light with a wavelength band of 490 nm or more and less than 550 nm, and 550 nm or more and less than 590 nm. yellow light, orange light of 590 nm or more and less than 640 nm, red light of 640 nm or more and less than 770 nm, near infrared light of 770 nm or more and less than 2500 nm, and infrared light of 2500 nm or more. May be set.

Moreover, the difference in the center wavelengths of the plurality of laser beams may be less than 100 nm. It is preferable that the spot diameters when the inner surface of the object to be inspected is irradiated are different from each other by 30 μm or more.

The contents described and illustrated above are detailed descriptions of the parts related to the technology of the present invention, and are merely examples of the technology of the present invention. For example, the above descriptions of configurations, functions, actions, and effects are examples of configurations, functions, actions, and effects of portions related to the technology of the present invention. Therefore, unnecessary parts may be deleted, new elements added, or replaced with respect to the contents described and illustrated above without departing from the gist of the technology of the present invention. Needless to say. In addition, to avoid confusion and to facilitate understanding of the technical aspects of the present invention, the description and illustrations provided above require specific explanation in order to enable the practice of the present technology. Descriptions of common technical knowledge, etc., that are not used are omitted.

REFERENCE SIGNS LIST 10 Cylindrical inner surface inspection device 11 Main body 12, 12A to 12C Inspection probe 13 Arm 14 Lifting device 15 Post 16 Laser light emitting device 17 Photoelectric conversion unit 18 Irradiation angle adjustment unit 19 Pedestal 20 Terminal device 21 Control unit 22 Processing unit 23 Display unit 71 Perforated substrate 71a Laser beam passage hole 72 Separation optical element 73a, 73b Photoelectric conversion sensor 74 Mirror 75 Collecting lens 76 Separation optical element 77a, 77b Photoelectric conversion sensor 80 Inspection object 101 Irradiation light 102 Reflection light 111 Main body 112 Inspection probe 116 Laser light emitting device 117 Photoelectric converter 118 Irradiation angle adjuster 130 Deflecting optical element

Claims (6)

a laser light emitting device that generates a plurality of laser beams with different central wavelengths for irradiating the inner surface of a cylindrical inspection object;
The plurality of laser beams from the laser light emitting device are transmitted as irradiation light to the distal end, the irradiation light is irradiated from the distal end to the inner surface of the inspection object, and the reflected light reflected from the internal surface of the inspection object is transmitted to the rear end. a scanning unit configured to sequentially irradiate irradiation light from the tip of the inspection probe to the entire periphery of the inner surface of the inspection object;
a photoelectric conversion unit that converts the reflected light emitted from the rear end of the inspection probe into an electrical signal for each wavelength;
a moving device for moving a main body including the laser light emitting device, the scanning unit, and the photoelectric conversion unit ;
The spot diameters when the plurality of laser beams are irradiated onto the inner surface of the inspection object are configured to differ from each other by 25 μm or more,
Cylindrical inner surface inspection device. The cylindrical inner surface inspection apparatus according to claim 1, wherein the center wavelengths of the plurality of laser beams are set to differ from each other by 100 nm or more. The center wavelengths of the plurality of laser beams are ultraviolet light with a wavelength band of 280 nm or more and less than 380 nm, violet light with a wavelength band of 380 nm or more and less than 430 nm, blue light with a wavelength band of 430 nm or more and less than 490 nm, green light with a wavelength band of 490 nm or more and less than 550 nm, and wavelength band of 550 nm or more and less than 590 nm. Yellow light, orange light of 590 nm or more and less than 640 nm, red light of 640 nm or more and less than 770 nm, near-infrared light of 770 nm or more and less than 2500 nm, and infrared light of 2500 nm or more. The cylindrical inner surface inspection device according to claim 2. The scanning unit makes the spot diameters of the spot lights different for each center wavelength when the inner surface of the inspection object is irradiated with a plurality of laser lights having center wavelengths different from each other, and scans the plurality of spot lights having different spot diameters. 2. The cylindrical inner surface inspection apparatus according to claim 1, wherein the inner surface of the object to be inspected is simultaneously irradiated with a plurality of spot lights in a state of being concentrically superimposed such that the center positions are the same. The scanning unit
A pipe-shaped member made of a transparent material that transmits laser light from the laser light emitting device as irradiation light through a hollow region, a cylindrical exterior member that accommodates the pipe-shaped member inside, and the exterior member. and a reflective member provided at the tip of the pipe-shaped member. the inspection probe that irradiates the inner surface of the object with the irradiation light, reflects the light reflected from the inner surface of the inspection object by the reflecting member, and transmits the light through a region other than the hollow region of the pipe-shaped member;
a rotating device that rotates the inspection probe;
The cylindrical inner surface inspection apparatus according to any one of claims 1 to 4 , comprising: The scanning unit
An irradiation angle adjustment unit for adjusting the irradiation angle of the laser light generated in the laser light emitting device, and a deflection optical element having a reflection or refraction angle in a 360-degree direction are provided at the tip, and the irradiation angle is adjusted by the irradiation angle adjustment unit. The laser light after the adjustment is transmitted to the tip inserted into the inside of the inspection object and reflected or refracted by the deflection optical element to sequentially irradiate the entire circumference of the inner surface of the inspection object as irradiation light. and the inspection probe that reflects or refracts light reflected from the inner surface of the object to be inspected by the deflection optical element and transmits the light to the end surface on the opposite side of the tip;
The cylindrical inner surface inspection apparatus according to any one of claims 1 to 4 , comprising:

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