JP2672771B2 - Through hole inner diameter measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a internal diameter measurement device of the through hole capable of measuring the inner diameter dimension of the small diameter of the through-hole with high accuracy.

[0002]

2. Description of the Related Art There are some products such as machined parts having very small through- holes. However, depending on the product, it is possible to measure a hole with a diameter of about 1 mm with a resolution of about 1 μm. Measurement may be required. When measuring the inside diameter of such a hole , there is a method of performing an optical measurement by irradiating the object to be inspected with light and measuring the shadow of the hole .

However, a method using a shadow of the holes will be measuring the end face or portion of a shadow accidentally hole, the measurement of the exact pore size impossible. In addition, there is a problem that the measurement becomes more difficult when the through hole is long. The present inventors are those diameters invented the device the inner diameter of very small holes like 1mm or less as accurately measuring device, in particular the inner diameter of the long holes length of the hole than the inner diameter precisely It is an object of the present invention to provide a through- hole inner diameter measuring device which can be effectively used in the case of measuring.

[0004]

The present invention has the following constitution in order to achieve the above object. In other words, the object to be inspected Der
And Se Tsu bets mechanism to accurately set to match the optical axis of the central axis of the through hole of the object to be inspected having a through-hole that the
It is placed in front of the through-hole apart from the object to be inspected,
A chip with multiple pinholes arranged symmetrically with respect to the optical axis.
And the light flux from each of the pinholes
Direct injection from the outside of the through-hole to the through-hole at one time
A light projecting optical system having a light source and lens system to the object
Located rearwardly of the through-holes spaced apart from the test body, the light-receiving optical wherein is reflected by the inner wall surface of the through-hole by receiving light emitted from said through hole, to observe the imaging position of the pinhole of the respective And a system. Also, the subject
Among the inspection object having a through-hole which is査subject of the through hole
And Se Tsu bets mechanism to accurately set the combined mandrel to the optical axis, distribution in front of the through-holes spaced apart from the test subject
And pinholes arranged symmetrically with respect to the optical axis.
With the chart, and from each of the pinholes
Direct light flux from outside the through-hole to the through-hole at once
To limit the diameter of the incident light beam and the incident light source
Iris of the eye, and a light projecting optical system having a lens system, the
And a light receiving optical system for detecting a position where the light beams reflected by the inner wall surface of the through hole coincide with each other on the optical axis behind the object to be inspected and cross the optical axis. Further, the light receiving optical system receives the reflected light from the inner wall surface of the through hole.
A camera is provided, and a linear guide with a linear encoder for moving and guiding the CCD camera in the optical axis direction is provided. Further, it is characterized in that an observation optical system for observing the state of the through hole of the inspection object is provided.

[0005]

[Function] The through-hole of the object to be inspected is accurately aligned with the optical axis by the inspecting object setting mechanism and is set through the projection optical system .
A light beam is made to enter the inner wall surface of the through hole from each pinhole provided in the chart . The reflected light reflected by the inner wall surface of the through hole is received by the light receiving optical system, and the image forming position of each pinhole is observed. The inner diameter of the through hole is measured from the observation position of the pinhole. Since the imaging position of the pinhole can be obtained with a predetermined sensitivity by the optical system, this enables highly accurate measurement. Also, each pinhole
The light receiving optical system covers the range where the light beams that are incident on the inner wall surface of the through hole from and are reflected by the inner wall surface of the through hole match and cross the optical axis.
Detect with. End point of the range in which each light beam coincides and crosses the optical axis
The inner diameter of the through hole can be measured by comparing the positions or the midpoints of both end points . The range in which the light reflected by the inner wall surface of the through hole crosses the optical axis can be accurately measured by a CCD camera that guides and moves with a linear guide. Further, by observing the state of the through hole of the inspection object with the observation optical system, the inspection object can be set accurately on the optical axis.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows the overall construction of an embodiment of the inner diameter measuring device for a through hole . The apparatus of the embodiment is a light projecting optical system A for irradiating an object having a through hole with light.
A light receiving optical system B for receiving the reflected light from the object to be inspected, a setting mechanism C for setting the object to be inspected by controlling its posture, and a state for observing the state of the through hole of the object to be inspected. an observation optical system and a D.

FIG. 2 is a block diagram showing the arrangement of the essential parts of the embodiment apparatus in an easy-to-understand manner. The projection optical system A is a light source 10
And the lens 51 and the lens 5 arranged on the light projecting side of the light source 10.
2 and diaphragm 16. In the embodiment, a variable focus lens is used as the lens 51 and a fixed focus lens is used as the lens 52.

The observation optical system D has an illumination light source 18 for illuminating an object to be inspected, a prism 20, and a CCD camera 22 for observation. A lens system is provided in front of the CCD camera 22 for enlargement. A half mirror is formed on the prism 20 and is arranged on the optical axis to irradiate the light to be inspected with the light from the illumination light source 18 and guide the reflected light from the object to be inspected to the CCD camera 22. The state of the through- hole of the body can be observed.

The inspection object setting mechanism C is for accurately arranging the through holes of the inspection object 30 on the optical axis, and includes a movement control mechanism for moving the inspection object 30 in the X and Y axis directions. An attitude control mechanism for controlling the attitude of the through hole in the axial direction. In this way, the setting mechanism C can set the position and orientation of the device under test 30 by controlling the four axes. The rotation control mechanism is arranged on the setting mechanism and can rotate the device under test 30 around the optical axis. Further, the setting mechanism C is provided on the moving mechanism in the optical axis direction, and the device under test 30 can be moved in the optical axis direction.

The light receiving optical system B is arranged behind the object to be inspected, and the lens 53 is arranged on the side close to the object to be inspected and the lens 54 is arranged behind it. Reference numeral 24 denotes a diaphragm arranged in front of the lens 53. A CCD camera 26 that receives light emitted from the lens 54 is arranged behind the lens 54. The CCD camera 26 can be moved in a direction orthogonal to the optical axis to adjust its position, and is supported so as to be movable in the optical axis direction. In FIG. 1, reference numerals 28 and 29 are linear guides for controlling the movement of the CCD camera 26 in the optical axis direction and the direction orthogonal to the optical axis by a linear encoder.

As described above, the through hole inner diameter measuring device of the embodiment has the light projecting optical system A and the light receiving optical system B arranged in front of and behind the object to be inspected. The optical arrangement is shown in FIG. . In the figure, each position of the lenses 51, 52, 53, 54 and C
The light receiving surface of the CD camera 26 is shown by a straight line. Although the light source 10 is at the left end of the figure, a chart 60 having a pinhole is arranged in front of it. FIG. 4 shows a front view of the chart 60.
In the optical system of the embodiment, the pinhole provided on the chart 60 is C
An image is formed on the light receiving surface of the CD camera 26, and the inner diameter of the through hole is measured from the image forming position. Therefore, the chart 60 has four pinholes 6 at the cross position as shown in the figure.
The one provided with 2 was used. In the embodiment, the pinhole 62
Has a diameter of 0.1 mm, and the distance between the pinholes 62 facing each other is 0.9 mm. The format of the chart 60 can be appropriately changed according to the measurement content.

The chart 60 is arranged at the focal length f ₁ of the lens 51. This makes pinhole 6
The light emitted from 2 enters the lens 52 as a parallel light flux. In the embodiment, a variable focus lens is used as the lens 51. The distance between the lens 51 and the lens 52 may be set appropriately. In FIG. 3, reference numerals 30a and 30b denote inspected objects, in which inspected objects having different inner diameters are set.

Lenses 52, 53, 54, CCD camera 2
6 is the focal lengths f ₂ , f ₃ , f of the lenses 52, 53, 54
₄ with respect to the placing in accordance with the position relation of FIG. That is, the lens 52 and the lens 53 are arranged at an interval of f ₂ + f ₃ , and both the lens 53 and the CCD camera 26 have the lens 5
The focal lengths of 4 are respectively set. Although the distance between the lens 53 and the lens 54 is based on f ₄ , the distance can be set to any distance W ₄ . The measuring device of the embodiment is characterized in that the inner wall surfaces of the through holes of the inspection objects 30a and 30b are irradiated with a light beam, and the reflected light from the inner wall surfaces is received by the light receiving surface of the CCD camera 26. Therefore, in front of the lens 52, there is provided a diaphragm 16 for narrowing the light beam and making it enter the inner wall surface of the through hole. Since the through hole is longer than the inner diameter, the light beam is made to enter the through hole at a very shallow angle.

According to the optical system arrangement of this embodiment, the lens 5
Since the lens 2 and the lens 53 are arranged at an interval of f ₂ + f ₃ , the light emitted from the lens 53 becomes a parallel light beam, and the chart 54 is formed on the light receiving surface of the CCD camera 26 by the lens 54.
The 0 pinhole 62 is imaged. As shown in FIG. 3, the difference in the inner diameters of the inspection objects 30a and 30b is magnified at a certain magnification as the difference in the image forming position of the pinhole on the light receiving surface of the CCD camera 26. Assuming that the distance from the center on the light receiving surface is R, the pinhole position on the light receiving surface of this CCD camera 26 is pinhole 6 from the center on the chart 60.
The distance to 2 is h, and the radius of the through hole of the inspection object is r, which is given by the following equation. _{R = (f 4 / f 3} ) {2r- (f 2 h / f 1)}

When the inner diameters of the through holes of the object to be inspected are r ₁ and r ₂ , the difference ΔR between the pinhole positions R ₁ and R ₂ observed on the light receiving surface of the CCD camera 26 is given by the following equation. ΔR = R ₂ −R ₁ = (2f ₄ / f ₃ ) (r ₂ −r ₁ ) Therefore, the difference in the radius of the through hole of the inspection object is K = 2f ₄ / f ₃ on the light receiving surface of the CCD camera 26. Will be detected at a magnification of. Since this sensitivity coefficient K is determined by the focal lengths of the lenses 53 and 54,
It is possible to measure with high accuracy by selecting f ₄ / f _{3 so as} to have a large value. In the embodiment, a zoom lens of 64 mm to 640 mm is used as the lens 51, and the lenses 52, 53 and 54 each have a focal length of 7 mm.
Lenses of 0 mm, 70 mm and 135 mm were used.

The pinhole position on the light receiving surface of the CCD camera 26 may be measured by an appropriate method.
A method of measuring one element on the light receiving surface of 6 as a scale unit, or a linear guide that moves the CCD camera 26 in a direction orthogonal to the optical axis is provided, and a linear encoder of this linear guide is read for measurement. Available.

Incidentally, the setting error of the optical system and the lens
Calibration error shall be calibrated using standard materials . When measuring the inner diameter of the through hole of the object to be inspected, after observing the position of the through hole with the observation optical system D, the through hole is accurately aligned with the optical axis by the setting mechanism C, and then the pinhole position is measured with the CCD camera 26. The inner diameter of the through hole is measured by detecting. According to the apparatus of the embodiment, the inner diameter can be measured with an accuracy of several μm with respect to the through hole having a diameter of 1 mm, and the measurement can be performed with extremely high accuracy. Further, the apparatus of this embodiment has a feature that it can measure up to about a through hole having an inner diameter of about 0.1 mm, and particularly can measure a long through hole having a length of several tens mm.

5 and 6 show the construction of another embodiment of the inner diameter measuring device of the through hole. In this embodiment, the lenses 53, 5 arranged behind the device under test 30 in the above embodiment
4 is not used, the CCD camera 26 is moved back and forth on the optical axis to detect the position where the light reflected by the inner wall surface of the through hole of the device under test 30 intersects the optical axis. Lens 5
The other configurations except 3, 54 are common to the above-mentioned embodiment.

In this embodiment, the chart 60, the lens 51,
The set position of 52 is the same as that of the above-mentioned embodiment as shown in FIG. The light emitted from the lens 52 is the diaphragm 16
Then, it is narrowed down and projected onto the inner wall surfaces of the inspection objects 30a and 30b. The light projected into the through hole is reflected by the inner wall surface of the through hole and is emitted rearward, but the beam width of the emitted light varies depending on the inner diameter dimensions of the inspection objects 30a and 30b. CC
The D camera 26 measures the inner diameter of the through hole by detecting the boundary position where the light reflected by the through hole crosses the optical axis.

In FIG. 6, the points P ₁ and Q _{1 of the} inspection object 30a are the boundary positions where the light reflected by the through hole intersects the optical axis, and the points P ₂ and Q _{2 of the} inspection object 30b are the optical axes. It is the boundary position that intersects with. These boundary positions P ₁ , Q
₁ , P ₂ and Q ₂ can be detected by moving the CCD camera 26 back and forth on the optical axis. That is, at the boundary position P, the number of spots on the light receiving surface of the CCD camera 26 becomes one from a plurality, and at the boundary position Q, the spots separate from one to a plurality. Therefore, the CCD camera 26 is moved back and forth to detect the boundary position. You can The CCD camera 26 is moved back and forth by the linear guide 28, and the front and rear position thereof can be accurately detected by the linear encoder.

According to the optical system arrangement of this embodiment, P ₁ and Q
Assuming that the midpoint position of _{1 is} a and the midpoint position of P ₂ and Q ₂ is b, a and b and the inner diameters of the through holes of the DUT are r ₁ and r ₂ as the sensitivity coefficient K Given in. b−a = K (r ₂ −r ₁ ) K = (2f ₁ f ₂ ² h) / (f ₂ h + f ₁ s) (f ₂ h−f ₁ s) where s is the light flux in the lens 52. Is the radius of the pinhole for. Therefore, also in the case of the apparatus of this embodiment, the inner diameter of the through hole can be measured with high sensitivity according to the above formula.

FIG. 7 shows still another embodiment of the through hole inner diameter measuring device. In this embodiment, the optical system is formed by removing the lens 52 from the embodiment shown in FIGS. That is, as shown in FIG. 7, the light from the light source 10 is collimated and emitted by the lens 51, and the inspection object 3
The light is focused by the pinholes provided in the pinhole plate 17 placed in front of 0a and 30b and enters the through holes. The light beam that has entered the through hole is reflected by the inner wall surface of the through hole,
Similar to the above embodiment, the CCD camera 26 is moved back and forth to detect the boundary position where the beams intersect on the optical axis.

In the case of the present embodiment, since the parallel light flux enters the through hole, the reflected light is also a parallel light flux. 30A to be inspected,
Crossing positions P ₁ , Q ₁ and P of the light reflected by 30 b and the optical axis
₂ , where the midpoint positions of Q ₂ and Q ₂ are a and b, respectively, and the sensitivity coefficient is K, then b−a = K (r ₂ −r ₁ ) K = 2f ₁ / h. Since the sensitivity coefficient K is determined by f ₁ and h, f
_By setting the value of ₁ to be larger than that of h, it is possible to perform the same precise measurement as in each of the above embodiments.

The through-hole inner diameter measuring device of each of the above-mentioned embodiments makes a light beam incident on the inner wall surface of the through-hole of the object to be inspected and detects the reflected light on the inner wall surface of the through-hole to measure it. By squeezing the light into the through hole and making the light incident at an extremely shallow angle with respect to the through hole, the inner diameter of the through hole becomes 0.1 m.
It is possible to accurately measure even a small-diameter through hole that is very difficult to measure accurately by the conventional method such as m. In particular, by adopting the optical arrangement as described above, there is a feature that the measurement can be easily performed even when measuring a through hole that is very long as compared with the inner diameter.
Further, by making the sensitivity coefficient K large at the time of measurement, it becomes possible to measure with a resolution of about 1 μm using a through hole having an inner diameter of 1 mm.

[0025]

According to the through-hole inner diameter measuring apparatus of the present invention, as described above, it is possible to measure the inner diameter of the through-hole with high accuracy by the non-contact method, and the conventional method can measure the inner diameter extremely. Accurate measurement can be performed even for a small-diameter through hole that was difficult to achieve. Further, when observing and measuring the image formation position of the pinhole, accurate measurement is possible, and when measuring from the range where the reflected light crosses the optical axis, the optical system arrangement is simple and accurate. It produces a remarkable effect such as good measurement.

[Brief description of the drawings]

FIG. 1 is an external view of an example of an inner diameter measuring device for a through hole.

FIG. 2 is an explanatory diagram showing a main part configuration of an inner diameter measuring device for a through hole.

FIG. 3 is an explanatory diagram showing an optical arrangement of an example of an inner diameter measuring device for a through hole.

FIG. 4 is a front view of a chart.

FIG. 5 is an explanatory diagram showing a main part configuration of another embodiment of the inner diameter measuring device for a through hole.

FIG. 6 is an explanatory diagram showing an optical arrangement of another embodiment.

FIG. 7 is an explanatory view showing an optical arrangement of still another embodiment of the inner diameter measuring device for a through hole.

[Explanation of symbols]

 10 Light source 16, 24 Aperture 17 Pinhole plate 18 Illumination light source 20 Prism 22, 26 CCD camera 30, 30a, 30b Inspected object 51, 52, 53, 54 Lens 60 Chart 62 Pinhole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Michihiko Ono 1-7-7 Nomizo Nishi, Matsumoto City, Nagano Nagano Prefectural Information Technology Laboratory (72) Inventor Katsuhiro Gomi 245 Chuo-dori, Shimosuwa Town, Suwa-gun, Nagano Prefecture Gomi Kogyo Co., Ltd. (56) Reference JP-A-49-60994 (JP, A) JP-A-63-58134 (JP, A) JP-A-60-76605 (JP, A) JP-A-7-4919 ( JP, A)

Claims (4)

(57) [Claims] 1. An inspection object having a through hole which is an inspection object.
Is disposed on the central axis of the body the through hole and the cell Tsu bets mechanism to accurately set in accordance with the optical axis, in front of the through-holes spaced apart from the test subject
Multiple pinholes are arranged symmetrically with respect to the optical axis.
Beam chart and luminous flux from each pinhole
Directly from the outside of the through hole toward the through hole at once
A light projecting optical system having a light source and a lens system to be incident, and a rear surface of the through hole, which is spaced apart from the object to be inspected.
Is, exits from the through-hole is reflected by the inner wall surface of the through hole
Shines the received light, the inside diameter measuring apparatus of the through hole, characterized by comprising a light-receiving optical system for observing an image forming position of the pinhole of the respective. 2. An inspection object having a through hole which is an inspection object.
Is disposed on the central axis of the body the through hole and the cell Tsu bets mechanism to accurately set in accordance with the optical axis, in front of the through-holes spaced apart from the test subject
Multiple pinholes are arranged symmetrically with respect to the optical axis.
Beam chart, and luminous flux from each pinhole
Directly from the outside of the through hole toward the through hole at once
In order to limit the incident light source and the diameter of the incident light flux
A light projecting optical system having a diaphragm and a lens system, and a light receiving optical system for detecting a position where each light flux reflected by the inner wall surface of the through hole on the optical axis behind the object to be inspected coincides and crosses the optical axis. An inner diameter measuring device for a through hole, comprising: 3. A light receiving optical system is provided with a CCD camera for receiving reflected light from the inner wall surface of the through hole, and a linear guide with a linear encoder for moving and guiding the CCD camera in the optical axis direction is provided. The inner diameter measuring device for a through hole according to claim 2. 4. An observation optical system for observing a state of a through hole of an object to be inspected is provided.
The through-hole inner diameter measuring device described.