JP2771546B2 - Hole inner surface measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hole inner surface measuring device for measuring the diameter and position of a concentric annular uneven portion on a hole inner surface in a non-destructive and non-contact manner.

[Conventional technology]

Conventionally, in order to measure the diameter of concentric annular concave and convex portions such as grooves and throttles provided on the inner surface of a hole with a relatively small diameter and the distance from the reference surface, various mechanical length measuring instruments are inserted into the hole. A method of measuring by contacting the inner surface of the hole has been adopted.

[Problems to be solved by the invention]

However, in such a conventional hole inner surface measuring device, since the length measuring device must be brought into contact with the hole inner surface,
If the workpiece is made of a flexible material, the inner surface of the hole may be deformed or damaged.

In addition, since it is impossible to make the contact surface between the inner surface of the hole and the length measuring device a complete line or point, it is not possible to increase the measurement accuracy and to insert a small-diameter hole into which the length measuring device cannot be inserted. The inner surface could not be measured.

An object of the present invention is to solve such a conventional problem and to provide a non-destructive, non-contact measuring apparatus for measuring the inner surface of a hole.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a focusing optical system capable of being displaced in a direction of an optical axis from a reference position, a control means for displacing the focusing optical system so as to always keep a focused state, and an object to be measured. A reflective optical system that can be inserted through the hole to be measured in the direction of the optical axis and obliquely oblique at an angle of 45 degrees at a predetermined interval from the reference position, and the optical axis of the object to be measured or the reflective optical system. An intra-hole measuring device provided with a moving means for moving in a direction, wherein a focusing optical system projects a pattern image onto a surface to be measured, and an imaging optical system which forms the projected pattern image A two-segment prism for dividing the light passing through the imaging optical system into two light beams having different optical path lengths, and a pair of image sensors arranged near the focal plane of the imaging optical system and capable of receiving the two light beams; Calculation processing of output signals from these image sensors That the calculating unit is intended to provide a display unit and the hole inner surface measuring device comprising a displaying a calculation result by the calculation unit.

(Operation)

The reflective optical system of the hole inner surface measuring device constructed as above is inserted into the hole of the DUT, and the focusing is performed with the optical axis of the focusing optical system set at the reference position aligned with the center line of the hole. When the optical system is activated, the control means operates to change the direction at a right angle by the reflecting optical system through the optical axis of the focusing optical system, and the focusing optical system moves from the reference position according to the distance until reaching the inner surface of the hole. It is displaced in the optical axis direction to a focus position.

From this displacement amount, the radius of the hole can be obtained by knowing the distance from the focusing optical system to the inner surface of the hole of the reference surface of the measured object.

In this state, when the measuring device and the object to be measured are relatively moved in the optical axis direction, when the hole diameter is equal to the hole diameter of the reference plane,
Since the focusing optical system is kept in focus at that position,
The distance between the focusing optical system and the reflecting optical system remains unchanged.

Next, when the concentric annular concavo-convex portion on the inner surface of the hole faces the reflected optical axis reflected by the reflecting optical system, the distance from the focusing optical system to the inner surface of the hole changes. Up and down in the direction of the optical axis, the direction of the unevenness can be determined from the direction of the displacement, the depth and height of the unevenness can be determined from the amount of displacement, and The distance from the reference plane can be known.

Also, with this measuring device, the reflecting optical system is rotated, for example, by 120 degrees, with the optical axis of the focusing optical system and the center line of the hole of the object to be measured in parallel, and the distance to the inner surface of the hole is measured three times. Then, three different distances can be obtained, and the hole diameter can be obtained from these values.

Then, as a focusing optical system, a pattern image is projected on the surface to be measured, and the projected image is formed on a pair of image sensors arranged so as to be shifted in the optical axis direction, and the output from these image sensors is output. If a device that performs arithmetic processing on a signal and measures the distance to the surface to be measured is used, extremely accurate measurement can be performed.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention. A fine moving table 2 is slidably mounted on the lower arm 1a of the U-shaped moving table 1 by, for example, an ant and a dovetail groove so as to be vertically slidable. The pinion 3 is rotatably mounted on the lower arm 1a. The pinion 3 is rotated by a stepping motor 4 to finely move the fine moving table 2 up and down. System 5
Are fixed with the optical axis l vertical.

A probe 6 is rotatably mounted on the upper arm 1b of the movable base 1 by a step motor (not shown) provided inside the movable base 1, and its rotation axis is made coincident with the optical axis l of the focusing optical system 5. A reflection optical system 7 is fixed to the lower surface of the probe 6 and its reflection surface 7a is inclined by 45 degrees with respect to the optical axis l, and the vertical optical axis l is moved 90 degrees to the horizontal reflection optical axis l 'by the reflection surface 7a. Bends many times.

The movable base 1 thus configured is vertically slidably mounted on the L-shaped stationary base 8, and the rack teeth 1c formed on the side surfaces of the movable base 1 are rotatably mounted on the stationary base 8. The movable table 1 is moved up and down by meshing with the pinion 9 and rotating the pinion 9 by a step motor 10.

In the figure, reference numeral 11 denotes a calculation unit for calculating the output signal of the focusing optical system 5, 12 a display unit for displaying the calculation result of the calculation unit 11, and 13 a rotation of the step motor 4 according to the output signal of the calculation unit 11. It is a control unit for controlling the movement.

The focusing optical system 5 used here may be of any type, but in view of the fact that the inner surface of the hole to be measured is a smooth curved surface, a pattern projection type is desirable.

FIG. 2 (a) shows the optical path of such a focusing optical system, where 51 is a plateau, 52 is a condenser lens, 53 is a pattern plate, 54 is a projection lens, 55 is a half mirror, and 56 is a projection mirror. An imaging lens, 57 is an imaging lens, 58 is a two-segment prism, 59 is an image sensor such as a line sensor disposed near the focal plane of the imaging optical system.

The light beam emitted from the light source 51 becomes parallel light by the condenser lens 52 and irradiates the pattern plate 53. The pattern formed on the pattern plate 53 passes through the projection lens 54, changes the optical path by 90 degrees by the half mirror 55, passes through the projection / imaging lens 56, and is enlarged and projected on the surface S to be measured.

The photographed image of the surface to be measured S passes through a projection / imaging lens 56, a half mirror 55, and an imaging lens 57, and is split into two by a half mirror surface 58a of a two-piece prism 58. The figure reaches the left half 59a, and the remaining part is bent 90 degrees by the half mirror surface 58a and the prism surface 58b, and then reaches the right half 59b in the figure of the image sensor 59.

Accordingly, the left half 59a and the right half 59 of the image sensor 59 are provided.
By comparing the images of b, the respective states of the front focus, the rear focus, and the focus can be known.

Returning to FIG. 1 again, an object to be measured in which the probe 6 of the measuring apparatus having such a focusing optical system 5 is fixed on the base plate 14
The movable table 1 is moved vertically by the stepping motor 10 by the stepping motor 10 so that it can be inserted into the hole 21 to be measured, and the reflection is bent 90 degrees by the reflection surface 7a of the reflection optical system 7. The optical axis l 'is set to be at the same height as the reference surface 20a of the DUT 20 (see FIG. 3A).

The relative position of the movable base 1 with respect to the fixed base 8 in this state is defined as the starting position of the movable base 1, and the reflected optical axis l 'is set at the center of the hole.
The optical system 5 focusing as intersect at S ₁ point 21a is in operation.

Thereby, the pattern plate 53 shown in FIG.
Is projected by a projection optical system, and the projected image is imaged by an imaging optical system and a two-piece prism 58.
An image is taken on the left half 59a and the right half 59b of 59.

Here, a left half 59a and a right half 59b of the image sensor 59 are provided.
Are a pair of line sensors, the left half 59a and the right half 59b
Since the imaging light beam reaching the optical path has a different optical path length by the base line length d of the two-segment prism 58, assuming that the pattern of the pattern plate 53 is, for example, a pinhole, its image is formed as shown in FIG. Points A and B are generally on surface 5 of image sensor 59.
It is located before and after 9c.

At this time, the amount of light received by each module Ai, Bi of each image sensor 59a, 59b is as shown in FIG. 4, for example, and the total amount of light is the same.

Now, each adjacent modules _{Ai, Ai + 1; Bi,} Bi + 1 of the outputs Pai, Pai _1; Pbi, and Pbi + _1, the total of those P _A, when a _{P B, P A = Σ |} Pai-Pai + ₁ | P _B = Σ | Pbi−Pbi + ₁ | and P _A −P _B is a value indicating the degree of focus.

Here, P _A -P _B = 0 Focus P _A -P _B > 0 Front pin P _A -P _B <0 Since the back pin state is shown, this value (P _A -P _B ) is calculated. In step 11, the step motor 4 is rotated by a required angle in a required direction through the control unit 13 to displace the focusing optical system 5 until P _A -P _B = 0. .

The amount of displacement from the reference position of the focusing optical system 5, FIG. 3 distance to S ₁ point shown in (a) is the arithmetic unit 11 of via the reflection optical system 7 from a predetermined position of the focusing optical system 5 hole 21 in the calculation, the distance D ₁ of the from the light value l to the point S ₁ of the pores diameter 21a is determined from this value.

Here, for example, the outer diameter of the probe 6 is made substantially equal to the inner diameter of the hole 21 so that the probe 6 can be fitted into the hole 21 so that the center line of the hole 21 coincides with the optical axis l of the focusing optical system 5. if this distance D ₁ is the radius r ₁ next to the hole in the diameter 21a, and the value is displayed on the display unit 12.

However, since it is not practical to replace the probe 6 according to the hole diameter, the center line of the hole 21 of the DUT 20 is made parallel to the optical axis 1 of the focusing optical diameter 5, and the probe having the reflection optical system 7 is provided. 6 is rotated around the optical axis l by 120 degrees, and the distance from the optical axis l to the inner surface of the hole is obtained at the stop position, whereby the radius r ₁ of the hole middle diameter portion 21a can be calculated by a known calculation method. The radius r ₁ thus obtained is displayed on the display unit 12.

Then, P _A when be moved moving base 1 downward by step motor 10 which reflected optical axis l 'is in the pores diameter portion 21a
Since −P _B = 0, the relative movement between the focusing optical system 5 and the reflecting optical system 7 does not occur.

When the moving table 1 is in the position shown in FIG. 3 (b), the reflection optical axis l reaches the inner surface S ₂ of the circumferential groove 21b, the value of P _A -P _B is changed in the positive or negative direction, In response to this, the step motor 4 rotates by a required angle in a required direction and is displaced to the total position.

From this displacement amount, the distance from the optical axis l to the point S _{2 in the same} manner
It is possible to obtain the D _2, the probe 6 In this case, it is possible to obtain the radius r ₂ by being rotated by 120 degrees to measure 3 times the distance to the circumferential groove 21b with.

Then, it is possible to obtain the P _A -P axial depth Z ₁ of the circumferential groove 21b from the moving amount from the value starting position of the moving base 1 at a point which varies from 0 to _B, a depth Z ₁ There is displayed on the display section 12 with the radius r ₂ of the circumferential groove 21b.

Further, it is possible to obtain the moving base 1 to move downward becomes the position shown in FIG. 3 (c) and the depth Z ₂ to the other wall surface of the circumferential groove 21b by stepper motor 10.

Further, when the movable table 1 is at the position shown in FIGS. 3 (d) and 3 (e), the radius r ₃ of the throttle 21c and the depth Z ₃ from the reference plane,
Z ₄ can be determined respectively.

As described above, the reflection optical system 7 need only bend the optical axis of the focusing optical system 5 by 90 degrees, and its size is extremely small. Therefore, for example, the length measuring device has a hole diameter of 5 to 20 mm and a depth of 50 mm. It is also possible to measure the inner surface of the hole in which the hole cannot be inserted.

In the embodiment, when the projection magnification ratio β of the focusing optical system 5 is 20, the measurement accuracy ε = ± 2 μm, and when β = 50, ε <± 1 μm.

In the above-described embodiment, the moving direction of the moving table 1 is set to the vertical direction, but the moving direction may be set to the horizontal direction.

Instead of moving the reflection optical system 7, the reflection optical system 7 may be fixed to a fixed base 30, and the object 20 may be moved in the optical axis direction, as schematically shown in FIG. In this way, the moving device can be simplified.

In addition, it goes without saying that the diameter and length of the hole that can be measured by the present invention are not limited to the above ranges.

〔The invention's effect〕

As described above, according to the hole inner surface measuring device of the present invention, it is possible to perform high-precision measurement that cannot be achieved by a non-destructive, non-contact, mechanical measuring device.

Further, since the reflection optical system may be extremely small, it is possible to measure a small-diameter hole inner surface into which a mechanical length measuring device is not inserted.

Further, by providing the focusing optical system with a projection optical system capable of projecting a pattern image on the surface to be measured, it is possible to accurately and easily measure the inner surface of the hole formed by a smooth curve.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention. FIGS. 2 (a) and 2 (b) are optical path diagrams and an enlarged view of a part of an example of the focusing optical system, and FIG. 3 (a). , (B), (c), (d), and (e) are explanatory views showing the measurement process, FIG. 4 is an explanatory view exemplifying a light receiving state of the image sensor, and FIG. 5 is another embodiment of the present invention. It is a schematic diagram showing an example. 1 ... moving table 2 ... fine movement table 5 ... focusing optical system, 6 ... probe 7 ... reflective optical system, 8 ... fixed table 11 ... arithmetic unit, 12 ... display unit 13 ... control , 20… DUT 21… Hole, 53… Pattern plate 58… Two-prism 59… Image sensor

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kenji Sakai 3-1-1, Otsuka, Bunkyo-ku, Tokyo Mamiya Koki Co., Ltd. (56) References JP 50-159355 (JP, A) JP JP-A-52-107855 (JP, A) JP-A-51-113754 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01B 11/00-11/30 G01C 3/00-3 / 32

Claims (1)

(57) [Claims] A focusing optical system capable of being displaced in a direction of an optical axis from a reference position; a control means for displacing the focusing optical system so as to always keep the focusing state; Can be inserted in the optical axis direction, and the reflection optical system obliquely oblique at an angle of 45 degrees at a predetermined interval from the reference position, and moving the object to be measured or the reflection optical system in the optical axis direction A hole inner surface measuring device provided with a moving means, wherein the focusing optical system projects a pattern image on a surface to be measured, an imaging optical system for forming a projected pattern image, and the imaging A two-segment prism for splitting light passing through the optical system into two light beams having different optical path lengths, a pair of image sensors arranged near the focal plane of the imaging optical system and capable of receiving the two light beams, and these image sensors An arithmetic unit for arithmetically processing the output signal from Hole inner surface measuring apparatus characterized by comprising a display unit for displaying the calculation result of calculation section.