JP7629176B2 - Optical inner surface measuring device - Google Patents

Description

The present invention relates to an optical inner surface measurement device, and in particular, to detect scratches on the inner surface of a hole in an object to be measured, and to measure the shape, depth, and geometric accuracy with high precision.

Conventionally, a commonly known method for detecting surface defects such as scratches on the inner wall surface of mechanical parts is to detect them from the intensity of reflected light when a light beam is irradiated onto the object being inspected. This method can detect the presence or absence of scratches relatively quickly, but it cannot accurately measure the dimensions of the scratches, such as their size, depth, and shape.

In contrast to the conventional methods described above, an optical inner surface measuring device has been disclosed that can measure scratches on the inner wall surface of a mechanical part with high accuracy, including its dimensions. The device irradiates the measurement target with light through a fixed translucent pipe, analyzes the interference light between the reflected light and a reference light, and makes corrections based on the translucent pipe (see, for example, Patent Document 1).

While the optical internal surface measuring device disclosed in Patent Document 1 can perform highly accurate measurements, it takes longer to obtain measurement results than when detecting scratches and other defects from the strength of reflected light. If one were to use the optical internal surface measuring device disclosed in Patent Document 1 to detect surface defects such as scratches from the strength of reflected light, accurate detection would not be possible because the light reflected back from the translucent pipe and the light reflected from the object being inspected would interfere with each other depending on the distance, resulting in varying light strengths.

JP 2015-232539 A

The present invention was made in consideration of the above-mentioned conventional circumstances, and its objective is to measure scratches on the inner surface of a hole in an object to be measured with high accuracy and in a short time.

One means for solving the above problem is an optical inner surface measuring device that inserts a probe into a hole in an object to be measured and irradiates the inner surface of the hole with a light beam, the optical surface measuring device comprising: a detection means that detects the presence or absence of surface defects on the inner surface of the hole based on the intensity of the reflected light of the light beam irradiated on the inner surface of the hole; a measurement means that measures the inner surface of the hole by an interference optical method; and a spectroscopic means that splits the light beam irradiated on the inner surface of the hole into a first irradiation light beam in a wavelength band for the detection means and a second irradiation light beam in a wavelength band for the measurement means.

The optical inner surface measuring device of the present invention can significantly reduce the measurement time required to detect and measure in detail surface defects on the inner surface of a hole in an object being measured.

1 is a diagram showing an image of measurement by a probe of the optical measuring device of the present invention. FIG. 1 is a diagram showing an image of measurement by a probe of the optical measuring device of the present invention. FIG. 1 is a diagram showing an image of measurement by a probe of the optical measuring device of the present invention. FIG. FIG. 1 is a diagram showing an image of an optical system configuration of an optical measuring device according to the present invention. 1 is a structural diagram of a probe unit according to an embodiment of the optical measuring device of the present invention; 1 is an overall configuration diagram of an optical measurement device according to an embodiment of the present invention; FIG. 4 is an operation flow diagram according to the embodiment of the optical measurement device of the present invention.

One of the features of this embodiment is that an optical inner surface measuring device, in which a probe is inserted into a hole provided in a measured object and a light beam is irradiated onto the inner surface of the hole, is configured as follows.
The device is configured to include a detection means for detecting the presence or absence of surface defects on the inner surface of the hole based on the intensity of reflected light of a light beam irradiated onto the inner surface of the hole, a measurement means for measuring the inner surface of the hole by an interference optical method, and a spectroscopic means for splitting the light beam irradiated onto the inner surface of the hole into a first irradiation light beam in a wavelength band for the detection means and a second irradiation light beam in a wavelength band for the measurement means.
With this configuration, it is possible to use the same probe to detect and measure defects on the inner surface of the hole of the object to be measured, thereby significantly reducing the measurement time required to detect and measure surface defects in detail compared to conventional methods.

Another feature is that, in addition to the above features, the wavelength of the second irradiation light beam is longer than the wavelength of the first irradiation light beam by 100 nm or more.
According to this configuration, the first irradiation light beam and the second irradiation light beam can be easily separated by wavelength.

Another feature is that in addition to the above features, a short-pass dichroic mirror is used in the spectroscopic means for splitting the first irradiation light beam and the second irradiation light beam in the wavelength band for the measuring means.
According to this configuration, since the spectroscopic analysis can be performed with a relatively simple structure, the probe can be made smaller.

Another feature, in addition to the above features, is that the first irradiation light beam split by the spectroscopic means is redirected by an optical path conversion means arranged at the tip side of the probe so as to be directly irradiated onto the inner surface of the hole to be measured.
With this configuration, there is no interference (light intensity) due to dimensional differences compared to when there is a translucent member between the object to be measured, so defects on the inner surface of the hole of the object to be measured can be detected more accurately.

Another feature, in addition to the above features, is that the second irradiation light beam split by the spectroscopic means is irradiated onto the inner surface of the hole via a translucent member arranged on the probe so as to surround the spectroscopic means.
According to this configuration, the transparent pipe can be used as a reference when acquiring three-dimensional shape data of the inner circumferential surface, so that the effects of vibration and noise can be eliminated and correct three-dimensional shape data of the inner circumferential surface can be acquired.

Another feature, in addition to the above features, is that the first irradiation light beam and the second irradiation light beam are rotationally irradiated onto the inner surface of the hole, and after the presence of a surface defect is detected by a detection means, the second irradiation light beam is irradiated onto the surface defect, and the inner surface including the surface defect is measured by a measurement means.
According to this configuration, the condition of the inner peripheral surface of the cylinder, including surface defects, can be measured in a short period of time.

Another feature is that, in addition to the above features, when the measuring means performs a measurement, the cross-sectional shape dimension data of the light- transmitting member is measured in advance in a calibration stage and stored in a computer. Then, when the dimension of the measured object is measured, the reflected light emitted by the rotation is captured, and the diameter (D = D0 + ΔR1 + ΔR2) is calculated from the radial distance (ΔR1, ΔR2) from the inner or outer surface of the light-transmitting pipe (light-transmitting member) to the inner surface of the measured object and the diameter value (D0) of the three-dimensional shape of the light-transmitting pipe (light-transmitting member) previously stored in the computer, thereby collecting and calculating corrected three-dimensional shape data that excludes the effects of rotational runout and rotational vibration of the optical path conversion means.
According to this configuration, the inner peripheral surface measurement of the measuring means can always be performed by comparative measurement with a light-transmitting pipe standard whose dimensions have been precisely calibrated, and a measuring instrument with very good repeatability of measurements can be obtained.

Hereinafter, an image of this embodiment will be described with reference to FIGS. 1A to 1C and FIG.
1A to 1C are diagrams showing measurement images in a probe portion of an optical measuring device according to this embodiment.
FIG. 2 is a diagram showing an image of the optical system configuration of the optical measurement device according to this embodiment.

First, a measurement image of the probe portion will be described with reference to FIGS. 1A to 1C.
FIG. 1A shows a state in which a laser beam (La) of a defect detection laser and a laser beam (Lb) of a measurement laser are irradiated from a probe (P) to an inner surface (Os) of a hole in an object to be measured (O).
FIG. 1B shows a state in which a defective portion (sd), such as a scratch, on an inner peripheral surface (Os) of a hole in an object to be measured (O) is irradiated with laser light (La) from a defect detection laser.
FIG. 1C shows a state in which a defective portion (sd), such as a scratch, on an inner peripheral surface (Os) of a hole in an object to be measured (O) is irradiated with laser light (Lb) from a measurement laser.

The probe (P) is movable along the axial direction of the hole of the object to be measured (O).
As shown in FIG. 1A, the probe is inserted into a hole in an object to be measured (O), and the inner surface of the hole is irradiated with laser light (La) from a defect detection laser and laser light (Lb) from a measurement laser while rotating.
A probe (P) moves along the axial direction of a hole in an object to be measured (O) while rotatingly irradiating an inner surface (Os) of the hole with laser light (La, Lb) [Figure 1A → Figure 1B].
As shown in FIG. 1B, defect detection can be performed by irradiating a defective portion such as a scratch on the inner peripheral surface of the hole with laser light (La) from a defect detection laser.
When defect detection is performed, a probe (P) moves to a position where a laser beam (Lb) from a measurement laser can be irradiated onto a defective portion (sd) [FIG. 1B→FIG. 1C].
As shown in FIG. 1C, the defect portion (sd) is irradiated with laser light (Lb) from a measurement laser and measured in detail.

Next, the configuration of the optical system in the measurement will be described with reference to FIG.
In FIG. 2, the same reference numerals as in FIG. 1 are used for the components corresponding to those in FIG.

A laser device for the defect detection laser wavelength band and a laser device for the measurement laser wavelength band are prepared separately. For example, a red-oscillating He-Ne laser (wavelength 632.8 nm) device is used as the laser device for the defect detection laser wavelength band. For example, a broadband light source (SLD light source) device with a wavelength set to 100 nm or longer than the wavelength of the defect detection laser is used as the laser device for the measurement laser wavelength band. More specifically, when a He-Ne laser device with a wavelength of 632.8 nm is used as the defect detection laser, a broadband light source device with a wavelength set to 732.8 nm or longer is used as the measurement laser.

The laser light (La) from the defect detection laser and the laser light (Lb) from the measurement laser are each introduced into separate optical fibers.

The laser light (La) from the defect detection laser propagates through one optical fiber and is split into two optical fibers by an optical coupler (c1).

One of the laser beams (La) split by the optical coupler (c1) is captured by the photodiode (f1). The output value of the photodiode (f1) at this time is stored in the computer (PC).

The other part of the laser light (La) branched by the optical coupler (c1) is combined with the laser light (Lb) of the measurement laser by the optical coupler (c2) and introduced into a single optical fiber.

The laser light (La) and the laser light (Lb) introduced into one optical fiber by the optical coupler (c2) are introduced into one optical fiber connected to the probe (P) via the optical coupler (c3).

The laser light (La) and the laser light (Lb) introduced into a single optical fiber by the optical coupler (c3) are incident at 45 degrees on the dichroic mirror (d1) in the probe (P).

Of the laser light incident on the dichroic mirror (d1) in the probe (P) at 45 degrees, the laser light (La) of the defect detection laser passes through the dichroic mirror (d1). On the other hand, the laser light (Lb) of the measurement laser is reflected at 45 degrees by the dichroic mirror (d1).

The laser light (La) that passes through the dichroic mirror (d1) is incident on the mirror (m) at an angle of 45 degrees and is reflected. The laser light (La) reflected by the mirror (m) is irradiated towards the target surface of the object to be measured. The laser light (La) is reflected by the target surface of the object to be measured, and the returning light is incident on the mirror (m) at an angle of 45 degrees and is reflected, so that the laser light (La) is directed again towards the dichroic mirror (d1). The laser light (La) then passes through the dichroic mirror (d1) again.

The laser light (Lb) of the measurement laser reflected by the dichroic mirror (d1) passes through the light-transmitting member (t1) and is irradiated toward the target surface of the object to be measured. The laser light (Lb) is directed again toward the dichroic mirror (d1) as interference light between the light beam reflected by the target surface of the object to be measured and the light beam partially reflected based on the light-transmitting member (t1). The laser light (Lb) then enters the dichroic mirror (d1) again at 45 degrees and is reflected.

The laser light (La) that passes through the dichroic mirror (d1) again and the laser light (Lb) that is reflected by the dichroic mirror (d1) again are introduced back into a single optical fiber that is connected to the optical coupler (c3).

The returning laser light (La) and laser light (Lb) reflected by the target surface (Os) of the object to be measured are introduced via an optical coupler (c3) into an optical fiber different from the one emitted from the laser device of the light source toward the probe (P). The laser light (La) and laser light (Lb) introduced into this optical fiber are then incident on a dichroic mirror (d2) in the optical measuring device main body (B).

The laser light (La) and the laser light (Lb) are separated by the dichroic mirror (d2).

The laser light (La) separated by the dichroic mirror (d2) is captured by the photodiode (f2). The output value of the photodiode (f2) at this time is then stored in the computer (PC).

The laser light (Lb) separated by the dichroic mirror (d2) is introduced into a spectroscope (s1) for analyzing interference light. The laser light (Lb) is then split into wavelengths by the spectroscope (s1) to obtain the light intensity of each wavelength. The waveform data of the light intensity of each wavelength obtained here is imported into a computer (PC) and analyzed.

Next, a more specific example will be described in detail with reference to Figures 3 to 5.

Figure 3 is a structural diagram of the probe 1 in the optical measurement device of this embodiment. A portion of the probe 1 is shown in cross section to show the internal structure.

The probe 1 is mainly composed of a motor 10, an optical path conversion unit 20, an optical fiber unit 30, and a transparent pipe unit 40.

The motor 10 is composed of a housing 11, a rotor magnet 12, a hollow rotating shaft 13, bearings 14a and 14b, a coil 15, and the like.
The rotor magnet 12 is a long cylindrical permanent magnet arranged so that N and S poles alternate on the outer circumferential surface of the cylinder. The hollow rotating shaft 13 is inserted through the center of the magnet 11, and its front and rear ends protrude from the front and rear ends of the rotor magnet 12, respectively. The rotor magnet 12 and the hollow rotating shaft 13 are fixed together and form the rotor part of the motor 10. The hollow rotating shaft 13 is supported rotatably on both sides in the axial direction by bearings 14a and 14b. Three coils 15 are fixed together with the housing 11 so as to face the outer circumferential surface of the cylinder of the rotor magnet 12. By sequentially passing current through the three coils 15, the rotor magnet 12 and the hollow rotating shaft 13, which are the rotor part, can be rotated.

The optical path changing unit 20 is composed of a mirror holding member 21, a connection flange 22, a dichroic mirror 23, a reflecting mirror 24, and the like.
The mirror holding member 21 holds the connection flange 22, the dichroic mirror 23, and the reflection mirror 24. The connection flange 22 has a stepped cylindrical shape, and the hollow rotating shaft 13 is positioned so as to pass through its center, connecting the optical path changing unit 20 and the motor 10. The dichroic mirror 23 is a short-pass dichroic mirror having a transmission band and a reflection band according to the wavelength range of light, and functions as a spectroscopic means. For example, there is a short-pass dichroic mirror with a cutoff wavelength of 650 nm, a transmission band of 410 nm to 633 nm, and a reflection band of 685 nm to 1600 nm, which can be used. The reflection mirror 24 is fixed to the mirror holding member 21 so as to be located on the tip side of the probe 1.

The optical fiber unit 30 is composed of an optical fiber 31, a first lens 32, a second lens 33, a lens holding member 34, and the like.
One end of the optical fiber 31 is inserted into the hollow rotating shaft 13 .
The first lens 32 is joined to one end of the optical fiber 31. The first lens 32 has a function of expanding the light beam from the optical fiber 31 and emitting it toward the second lens 33, and also has a function of collecting return light from the object to be measured and guiding it to the optical fiber.
The second lens 33 is disposed at a position facing the first lens 32 via the lens holding member 34. The second lens 33 has a function of roughly parallelizing the light beam that has passed through the first lens 32 from the optical fiber 31 and emitting the parallel light toward the dichroic mirror 23, and also has a function of collecting the return light from the object to be measured and emitting the parallel light toward the first lens 32.
The lens holding member 34 is located inside the mirror holding member 21 and is fixed integrally with the optical fiber 31 .

The light-transmitting pipe unit 40 is composed of a light-transmitting pipe 41, an upper cover 42, a lower cover 43, supports 44, a fixing plate 45, a connecting plate 46, and the like.
The light-transmitting pipe 41 is formed into a hollow cylindrical shape using a light-transmitting member, and is disposed so that its inner peripheral surface faces the dichroic mirror 23 of the optical path changing unit 20. An upper cover 42 and a lower cover 43 are provided on both axial sides of the light-transmitting pipe 41. The upper cover 42 and the lower cover 43 are disk-shaped with holes through which the optical path changing unit 20 can be inserted. A plurality of support posts 44 are attached to the upper cover 42. The plurality of support posts 44 are fixed to a fixing plate 45 on the opposite side of the upper cover 42. They are further fixed to the housing 11 of the motor 10 via a connecting plate 46 fixed integrally to the fixing plate 45.

Figure 4 is a diagram showing the overall configuration of the optical inner surface measurement device of this embodiment. The main components are the probe 1, the device body 50, and the measurement table 60.

The probe 1 is fixed to the measurement table 60. A tube 35 is connected to the device body 50 from the side opposite the output of the motor 10 of the probe 1. The tube 35 is a flexible tube through which the optical fiber 31 passes.

The device body 50 houses inside it the defect detection laser device, the measurement laser device, the optical coupler, the dichroic mirror, the spectrometer, and other optical system elements described in FIG. 2, a computer for analysis, and a drive circuit for the motor 10 of the probe 1. It also has a monitor 51 that displays the analysis results.

The measurement table 60 has a stand 62 fixed to a base 61, and a slider 64 moves up and down together with the probe 1 by a slider motor 63. The object to be measured 70 is set on a centering jig 65 fixed to the base 61, and the optical probe 1 moves in and out of a deep hole 70h in the object to be measured 70.

FIG. 5 is a flow chart showing the measurement method and operation of the optical inner surface measuring device of this embodiment.
The measurement is carried out according to the following procedure.

[1] Work Setting The workpiece 70 is set on the centering jig 65.

[2] Scanning of defect detection laser light By operating the slider motor 63, the probe 1 is inserted into the hole 70h of the measurement object 70. While the probe 1 moves in the axial direction of the hole 70h, the inner peripheral surface of the hole 70h is irradiated with the laser light of the defect detection laser in a rotary manner, thereby scanning the inner peripheral surface of the hole 70h with the defect detection laser light.

[3] Detection of Defects The presence or absence and location of defects such as uneven scratches on the inner surface of hole 70h are identified by comparing the output value of the photodiode of the laser light from the defect detection laser, which has been stored in advance in the computer of the device main body 50, with the output value of the photodiode that receives the return light of the laser light irradiated onto the inner surface of hole 70h.

[4] Slider Fast Forward The slider 64 is fast forwarded by the slider motor 63 to move the probe 1 to a position where the laser beam from the measurement laser can be irradiated onto the identified defective portion.

[5] Inner surface measurement by optical interference: Laser light from a measurement laser is irradiated onto the inner surface including the defect site, and precise three-dimensional data is obtained from the return light by optical interference.
If there are multiple defects on the inner surface of hole 70h, return to step [4] and move probe 1 to a position where the next defect can be irradiated with laser light from the measurement laser, and measure it in the same manner.
Once the measurements have been completed for all defect areas, proceed to the next step.

[6] Display of Results Analysis results such as the area and depth of defects such as uneven scratches are displayed on the monitor 51 based on the acquired measurement data obtained by optical interference.

[7] Saving of measurement data The measurement result data is saved in a storage device in the computer and the process is terminated.

Here, we will explain the effect of positioning the translucent pipe 41 in the optical inner surface measuring device of this embodiment so that its inner surface faces the dichroic mirror 23 of the optical path conversion unit 20, as shown in Figure 3.
The diameter of the inner or outer peripheral surface of the transparent pipe 41 and the three-dimensional shape data or two-dimensional cross-sectional shape data are stored in a computer in advance. When measuring the inner peripheral surface of the hole 70h of the object 70 (FIG. 4), the reflected light of the measurement laser beam emitted from the probe 1 is captured to obtain the radial distance from the inner or outer peripheral surface of the transparent pipe 41 to the inner peripheral surface of the object to be inspected. When the diameter of the inner peripheral surface (outer peripheral surface) of the transparent pipe 41 stored in the computer in advance is D0, and the distances from the inner peripheral surface (outer peripheral surface) of the transparent pipe 41 to the inner peripheral surface of the object to be inspected in the diameter D0 direction are ΔR1 and ΔR2, the inner diameter of the hole 70h (D=D0+ΔR1+ΔR2) can be calculated. This eliminates the effects of rotational runout and rotational vibration of the optical path conversion means and collects correct dimensional data.
The applicant has described in more detail in Patent Application No. 2020-060327 and elsewhere how cross-sectional shape dimensional data of a translucent member, such as a translucent pipe, is stored in a computer in advance at a calibration stage, and the inner surface of the object to be measured is measured with high precision using this as a reference.

The above describes an embodiment of the present invention, but the present invention is not limited to the above-mentioned examples, and can be modified as appropriate without departing from the spirit of the present invention.

1: Probe 10: Motor 11: Housing 12: Rotor magnet 13: Hollow rotating shaft 14a, 14b: Bearing 15: Coil 20: Optical path conversion unit 21: Mirror holding member 22: Connection flange 23: Dichroic mirror (spectroscopic means)
24: Reflection mirror 30: Optical fiber unit 31: Optical fiber 32: First lens 33: Second lens 34: Lens holding member 35: Tube 40: Light-transmitting pipe unit 41: Light-transmitting pipe (light-transmitting member)
42: Upper cover 43: Lower cover 44: Support 45: Fixing plate 46: Connection plate 50: Device body 51: Monitor 60: Measurement table 61: Base 62: Stand 63: Slider motor 64: Slider 70: Object to be measured

Claims (7)

1. An optical inner surface measuring device that inserts a probe into a hole provided in an object to be measured and irradiates an inner peripheral surface of the hole with a light beam,
a detection means for detecting the presence or absence of a surface defect on the inner peripheral surface of the hole based on the intensity of reflected light of a light beam irradiated on the inner peripheral surface of the hole;
a measuring means for measuring the inner peripheral surface of the hole by an interference optical method;
and a spectroscopic means for splitting the light beam irradiated onto the inner surface of the hole into a first irradiation light beam in a wavelength band for the detection means and a second irradiation light beam in a wavelength band for the measurement means. The optical inner surface measuring device according to claim 1, characterized in that the wavelength of the second irradiation light beam is at least 100 nm longer than the wavelength of the first irradiation light beam. The optical inner surface measuring device according to claim 1 or 2, characterized in that the spectroscopic means is a short-pass dichroic mirror. The optical inner surface measuring device according to any one of claims 1 to 3, characterized in that the first irradiation light beam split by the splitting means is redirected by an optical path changing means arranged at the tip side of the probe and directly irradiated onto the inner surface of the hole. The optical inner surface measuring device according to any one of claims 1 to 4, characterized in that the second irradiation light beam split by the splitting means is irradiated onto the inner surface of the hole via a translucent member arranged on the probe so as to surround the splitting means. the first irradiation light beam and the second irradiation light beam are rotary irradiated onto an inner circumferential surface of the hole;
After detecting the presence of the surface defect by the detection means,
6. The optical inner surface measuring device according to claim 1, wherein the second irradiation light beam is irradiated onto the surface defect, and the inner circumferential surface including the surface defect is measured by the measuring means. The light-transmitting member has a substantially cylindrical shape,
The cross-sectional shape and dimension data of the light-transmitting member is stored in a computer in advance,
When the measuring means measures the inner peripheral surface of the hole, it captures the reflected light that has been rotated and radiated, and calculates a diameter (D=D0+ΔR1+ΔR2) from the radial distance (ΔR1, ΔR2) from the inner peripheral surface or the outer peripheral surface of the light-transmitting member to the inner peripheral surface of the hole and a diameter value (D0) of the three-dimensional shape of the light-transmitting member that has been stored in advance in a computer;
6. The optical inner surface measuring device according to claim 5 , wherein the three-dimensional shape data after correction, in which the effects of rotational runout and rotational vibration of the optical path changing means are eliminated, is collected and calculated.

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