JP7583259B2 - Inner surface shape measuring machine and alignment method for the inner surface shape measuring machine - Google Patents

Description

The present invention relates to a technique for measuring the inner shape of a small hole formed in a workpiece.

Among shape measuring devices that measure the shape of a workpiece by moving a contact or non-contact probe and the workpiece relative to one another, there is known an inner shape measuring machine that measures the roundness of the workpiece by rotating the workpiece around a rotation axis. To measure roundness with an inner shape measuring machine, it is necessary to align the rotation axis with the axis center of the workpiece.

Patent Document 1 discloses a technique for measuring the roundness of a hole by contacting the contact of a detector with the inner circumference of the hole in a workpiece placed on a rotating table. In the technique described in Patent Document 1, the contact of the detector is contacted with the outer circumference of the workpiece in advance, and the runout of the workpiece is observed at low magnification while rotating the rotating table, and the position of the workpiece is adjusted to reduce the runout.

JP 2006-145344 A

When measuring the inner shape of a small hole using an inner shape measuring instrument, alignment of the small hole becomes an issue. That is, when a probe is inserted into the small hole and the workpiece is rotated, there is a problem that the probe will collide with the hole wall.

In contrast, when aligning using a hole and a coaxial part, as in the technology described in Patent Document 1, there are limitations to the shape of the object that can be measured.

In addition, if an operator inserts the probe while checking it with an observation microscope, the operator must be highly skilled. In this case, automation is difficult and there is a risk of the probe colliding with the wall of the hole due to an operating error.

The present invention was made in consideration of these circumstances, and aims to provide an inner surface shape measuring machine that properly aligns the position of a hole, and an alignment method for the inner surface shape measuring machine.

One aspect of an inner surface shape measuring machine for achieving the above object includes a rotating body that rotates around a rotation axis parallel to a first direction, a linear tilt stage supported by the rotating body, the linear tilt stage being capable of changing the position in a plane perpendicular to the first direction relative to the rotating body and the tilt relative to the plane, a contact or non-contact probe extending parallel to the first direction, the probe being movable in the first direction by a first linear mechanism, a displacement detector that detects the displacement of the inner surface of a fine hole in a workpiece fixed to the linear tilt stage and rotating with the rotating body using a probe, a camera having an optical axis parallel to the first direction, and a first position of the hole pattern of the reference workpiece at a first rotation angle of the rotating body and a second position in the first direction different from the first position for a reference workpiece having a known shape and having a hole pattern formed therein, fixed to the linear tilt stage, The inner surface shape measuring machine includes a first observation control unit that observes, by a camera, a first position and a second position of a hole pattern of a reference workpiece at a second rotation angle different from the first rotation angle of the rotating body; a rotation center coordinate calculation unit that calculates the rotation center coordinate of the rotating body from the coordinates of the first and second positions of the fine hole at the observed first rotation angle of the rotating body and the first and second positions of the fine hole at the second rotation angle of the rotating body; a second observation control unit that observes, by a camera having an optical axis parallel to the first direction, a third position of the fine hole of the workpiece to be measured that is fixed to a linear tilt stage and a fourth position that is a position in the first direction different from the third position; and a position and tilt calculation unit that calculates the position and tilt of the fine hole from the rotation center coordinate of the rotating body and the third and fourth positions of the fine hole of the rotating body.

According to this aspect, the hole position can be properly aligned based on the fine hole information. This is particularly effective for extremely small holes with an inner diameter of 500 μm or less.

It is preferable to have a stage control unit that controls the linear tilt stage based on the fine hole information, including the position and tilt of the fine hole, and keeps the deviation between the center axis of the fine hole and the rotation axis within a target value. This makes it possible to automatically align the hole position.

It is preferable that the camera is movable in a first direction by a first linear motion mechanism, and the second observation control unit moves the focal position of the camera to a third position and a fourth position of the fine hole by the first linear motion mechanism. This allows the camera to be properly focused on the third position and the fourth position of the fine hole, so that the fine hole can be properly observed by the camera.

It is preferable that the first rotation angle and the second rotation angle are different from each other by 180 degrees. This allows the position and inclination of the fine hole to be calculated with high accuracy.

It is preferable to have a coaxial lighting optical system that emits light coaxially with the optical axis of the camera. This allows the fine hole in the workpiece to be properly illuminated, so that the fine hole can be properly observed by the camera.

It is preferable that the reflector has a sponge-like or clay-like reflector, which reflects light incident from an opening on the camera side of a fine hole in a workpiece placed between the camera and the linear tilt stage, to the fine hole at an opening on the linear tilt stage side. This allows light incident from the opening on the camera side of a fine hole in the workpiece to be reflected to the fine hole at the opening on the linear tilt stage side without damaging the workpiece.

The device comprises a flexible open-cell structure and a light source that allows light to enter the open-cell structure, and it is preferable that the light from the light source is allowed to enter the open-cell structure from an opening on the linear motion tilt stage side of the fine hole in the workpiece that is disposed between the camera and the linear motion tilt stage. This allows light to be appropriately allowed to enter from the opening on the linear motion tilt stage side of the fine hole in the workpiece.

To achieve the above object, an alignment method for an inner surface shape measuring machine includes a rotating body that rotates around a rotation axis parallel to a first direction, a linear tilt stage supported by the rotating body, the linear tilt stage being capable of changing the position in a plane perpendicular to the first direction relative to the rotating body and the tilt relative to the plane, and a displacement detector that is a contact or non-contact probe extending parallel to the first direction and is movable in the first direction by a first linear mechanism, and detects the displacement of the inner surface of a fine hole in a workpiece to be measured that is fixed to the linear tilt stage and rotates together with the rotating body, the alignment method comprising: fixing a reference workpiece having a known shape and on which a hole-shaped pattern is formed to the linear tilt stage, detecting a first position of the hole-shaped pattern of the reference workpiece at a first rotation angle of the rotating body, a second position that is different in the first direction from the first position, and a displacement detector that detects the displacement of the inner surface of a fine hole in a workpiece to be measured that is fixed to the linear tilt stage and rotates together with the rotating body, the alignment method comprising the steps of: fixing a reference workpiece having a known shape and on which a hole-shaped pattern is formed to the linear tilt stage; detecting a first position of the hole-shaped pattern of the reference workpiece at a first rotation angle of the rotating body, a second position that is different in the first direction from the first position, and a displacement detector that detects a first position of the hole-shaped pattern of the reference workpiece at a first rotation angle of the rotating body; The alignment method for an inner surface shape measuring machine includes a first observation control step of observing a first position and a second position of a hole pattern of a reference workpiece at a second rotation angle different from the rotation angle by a camera having an optical axis parallel to a first direction, a rotation center coordinate calculation step of calculating the rotation center coordinate of the rotating body from the coordinates of the first position and the second position of the fine hole at the observed first rotation angle of the rotating body and the first position and the second position of the fine hole at the second rotation angle of the rotating body, respectively, a second observation control step of fixing the workpiece to be measured to a linear tilt stage and observing a third position of the fine hole of the workpiece to be measured and a fourth position that is different in the first direction from the third position by a camera having an optical axis parallel to the first direction, and a position and inclination calculation step of calculating the position and inclination of the fine hole from the rotation center coordinate of the rotating body and the third position and the fourth position of the fine hole of the rotating body.

According to this aspect, the hole position can be properly aligned based on the fine hole information. This is particularly effective for extremely small holes with an inner diameter of 500 μm or less.

The present invention allows the hole positions to be properly aligned.

FIG. 1 is a schematic diagram showing the configuration of an inner surface shape measuring machine. FIG. 2 is a schematic diagram showing an example of a non-contact type and a contact type probe. FIG. 3 is a block diagram showing the electrical configuration of the inner surface shape measuring machine. FIG. 4 is a flowchart showing an example of a process of an alignment method for an inner surface shape measuring machine. FIG. 5 is a schematic diagram showing observation of the upper opening of a fine hole by a camera. FIG. 6 is a diagram showing the positional relationship between the rotation axis of the rotor, the upper opening when the rotor is at a set angle θ=0°, and an image of the upper opening within the shooting range of the camera. FIG. 7 is a schematic diagram showing observation of the lower opening of a fine hole by a camera. FIG. 8 is a diagram showing the positional relationship between the rotation axis of the rotor, the lower opening when the rotor is at a set angle θ=0°, and an image of the lower opening within the shooting range of the camera. FIG. 9 is a diagram showing the positional relationship between the rotation axis of the rotor, the upper opening when the rotor is at a set angle θ=180°, and an image of the upper opening within the shooting range of the camera. FIG. 10 is a diagram showing the positional relationship between the rotation axis of the rotor, the lower opening when the rotor is at a set angle θ=180°, and an image of the lower opening within the shooting range of the camera. FIG. 11 is a diagram for explaining the movement target coordinates of the upper opening and the movement target coordinates of the lower opening. FIG. 12 is a diagram showing the relationship between the camera and the small hole in the workpiece caused by the workpiece setting jig. FIG. 13 is a schematic diagram showing observation of an intermediate position of a fine hole by a camera. FIG. 14 is a schematic diagram showing observation of a small hole in a workpiece by a camera when the position of the small hole is significantly deviated from the rotation axis. FIG. 15 is a diagram showing the locus of the central coordinates of the upper opening of the fine hole within the shooting range of the camera when the rotating body is rotated. FIG. 16 is a diagram showing the optical path of observation light entering the camera at the lower opening of a fine hole in a workpiece. FIG. 17 is a diagram showing the state of observation of the lower opening of a small hole in a workpiece by a camera. FIG. 18 is a diagram showing the insertion of a sponge-like reflector into the lower opening side of a small hole in a workpiece. FIG. 19 is a diagram showing the insertion of a clay-like reflector into the lower opening side of a small hole in a workpiece. FIG. 20 is a diagram showing the insertion of a scatterer into the lower opening side of a small hole in a workpiece. FIG. 21 is a flowchart showing the process of an alignment method for an inner surface shape measuring machine according to another embodiment of the present invention. FIG. 22 is a flowchart showing the process of registering the position of the rotation center coordinates. FIG. 23 is a flow chart showing an alignment process for a workpiece that is an object to be measured. FIG. 24 is a plan view showing an example of calculation of the rotation center coordinates when the fine hole in the workpiece has a shape with a protrusion inside. FIG. 25 is a plan view showing an example of calculation of the rotation center coordinates using a reference workpiece. FIG. 26 is a diagram showing an example of a reference workpiece having a planar shape.

A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

<Configuration of inner surface shape measuring machine>
Fig. 1 is a schematic diagram showing the configuration of an inner surface shape measuring machine 10 according to this embodiment. The inner surface shape measuring machine 10 is a device that measures the inner surface shape (roundness, etc.) of a small hole H formed in a workpiece W. In this example, the small hole H is a small hole formed along the central axis of the workpiece W. The inner diameter of the small hole H is extremely small (for example, the inner diameter is 500 μm or less). In Fig. 1, the X direction, Y direction, and Z direction are directions perpendicular to each other, the X direction is a horizontal direction, the Y direction is a horizontal direction perpendicular to the X direction, and the Z direction is a vertical direction.

As shown in FIG. 1, the inner surface shape measuring machine 10 includes a main body base 12, a rotating body 14, a linear tilt stage 16, a workpiece mounting jig 18, a column 20, a carriage 22, an arm 24, a displacement detector 28, and a camera 34.

The rotating body 14 is fixed on the main body base 12. Inside the main body base 12, there are provided a motor (not shown), an encoder (not shown), and a high-precision rotation mechanism (not shown), which are connected to the rotating body 14. The rotating body 14 rotates with high precision about a rotation axis A 2 _R parallel to the Z direction (an example of a first direction) by being driven by the motor. In addition, the rotation angle of the rotating body 14 is detected by a rotation angle signal output from the encoder.

The linear tilt stage 16 (an example of a linear tilt stage) is supported by the rotating body 14 so as to be movable relative to the rotating body 14. The linear tilt stage 16 translates in the X and Y directions when driven by a motor (not shown), and can change the position of the workpiece W fixed to the linear tilt stage 16 in a plane perpendicular to the Z direction (in the XY plane). The linear tilt stage 16 also tilts in the X and Y directions when driven by a motor (not shown), and can change the inclination of the workpiece W fixed to the linear tilt stage 16 with respect to the XY plane.

The workpiece setting jig 18 is placed on the linear motion tilt stage 16. A workpiece W is set on the workpiece setting jig 18. That is, the workpiece W is fixed to the linear motion tilt stage 16 via the workpiece setting jig 18. The workpiece W has a small hole H with an extremely small diameter. The small hole H passes straight through the inside of the workpiece W from an upper opening O _U (see FIG. 5 ) to a lower opening O _D (see FIG. 7 ).

In order to measure the inner shape, such as the roundness, of a small hole H in a workpiece W using the inner shape measuring machine 10, it is necessary to align the workpiece W so that the central axis _AH of the small hole H in the workpiece W is coaxial with the rotation axis _AR of the rotor 14. This alignment of the workpiece W will be described later. Fig. 1 shows the state of the workpiece W before alignment. The aligned workpiece W rotates around the rotation axis _AR together with the rotor 14.

A column (support) 20 extending parallel to the Z direction is erected on the main body base 12. The lower end of the column 20 is fixed to the upper surface of the main body base 12.

The carriage 22 is supported by the column 20 so as to be movable in the Z direction. The carriage 22 moves in the Z direction by being driven by a motor (not shown). The carriage 22 corresponds to a vertical linear motion mechanism (an example of a first linear motion mechanism) for moving the displacement detector 28 and the camera 34 in the Z direction.

The arm 24 is supported by the carriage 22 so as to be movable in the X direction (an example of a direction perpendicular to the first direction). The arm 24 moves in the X direction by being driven by a motor (not shown). The arm 24 corresponds to a horizontal linear motion mechanism for moving the displacement detector 28 and the camera 34 in the X direction.

The displacement detector 28 is supported by the arm 24. The displacement detector 28 is equipped with a non-contact or contact probe 30.

Figure 2 is a schematic diagram showing an example of the probe 30. 202A in Figure 2 shows the non-contact type probe 30. The displacement detector 28 (see Figure 1) equipped with the non-contact type probe 30 includes a light-emitting element (not shown) that emits detection light and a light-receiving element (not shown) that receives reflected light of the detection light emitted from the light-emitting element. The non-contact type probe 30 includes an optical fiber 38 and a reflecting mirror 40. The light emitted from the light-emitting element (not shown) of the displacement detector 28 (see Figure 1) is guided to the reflecting mirror 40 by the optical fiber 38, reflected by the reflecting surface of the reflecting mirror 40, and incident on the workpiece W. The reflected light reflected by the workpiece W is incident on the reflecting mirror 40, reflected by the reflecting surface of the reflecting mirror 40, and guided to the optical fiber 38. The reflected light guided to the optical fiber 38 is input to a light-receiving element (not shown) of the displacement detector 28. The displacement detector 28 detects the displacement of the workpiece W based on the reflected light received by the light-receiving element.

As a method for the non-contact displacement detector 28, known methods such as a laser interferometer, a white light interferometer, SD-OCT (Spectral Domain-Optical Coherence Tomography), and SS-OCT (Swept Source-Optical Coherence Tomography) can be applied.

The displacement detector 28 may detect the displacement of the workpiece W in a contact manner. 202B in FIG. 2 shows a contact-type probe 30. The contact-type probe 30 has a contactor 42 at its tip that is biased toward the workpiece W. When the contactor 42 comes into contact with the workpiece W, the contactor 42 is displaced according to the shape of the workpiece W. The displacement of the contactor 42 is transmitted to the displacement detector 28 via the probe 30. The displacement detector 28 detects the displacement of the workpiece W based on the displacement of the contactor 42.

The displacement detection mechanism of the contact type displacement detector 28 can be a known mechanism such as an LVDT (Linear Variable Differential Transformer), an interferometer, an optical triangulation method, or a thin film distortion measurement method. Furthermore, the displacement detector 28 can be a mechanism that vibrates the contact 42 at a resonant frequency and utilizes the change in the resonant point due to contact.

Returning to the explanation of FIG. 1, when the roundness of a small hole H in a workpiece W is measured using the inner surface shape measuring machine 10, the probe 30 is moved in the Z direction together with the displacement detector 28 by the carriage 22 and inserted into the small hole H in the workpiece W. The displacement detector 28 detects the displacement of the hole wall (inner surface) of the small hole H using the probe 30.

The camera 34 is supported by the arm 24 with its optical axis A _C (see FIG. 12) parallel to the Z direction and facing downward.

The camera 34 includes a coaxial epi-illumination optical system 35 (see FIG. 3, an example of a coaxial illumination optical system) and a magnifying optical system (microscope) (not shown) that enlarges and projects the object to be observed. The coaxial epi-illumination optical system 35 includes an illumination light source (not shown) and a half mirror (not shown) that outputs light from the illumination light source as illumination light coaxial with the optical axis A _C of the camera 34. The camera 34 can irradiate the object to be observed with illumination light coaxial with the optical axis A _C of the camera and capture an enlarged image of the object to be observed. Although coaxial epi-illumination is used here, oblique illumination may also be used.

In the thus configured inner surface shape measuring machine 10, the workpiece W is aligned, the probe 30 is inserted into the fine hole H in the workpiece W, the rotor 14 is rotated to move the workpiece W and the probe 30 relative to each other, and the displacement of the hole wall of the fine hole H is detected by the displacement detector 28, thereby measuring the roundness of the fine hole H.

<Electrical configuration of the inner surface shape measuring machine>
3 is a block diagram showing an electrical configuration of the inner surface shape measuring machine 10. The inner surface shape measuring machine 10 includes a control device 50.

The control device 50 is realized by a general-purpose computer such as a personal computer or a microcomputer. The control device 50 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an input/output interface. In the control device 50, various programs such as a control program stored in the ROM are expanded into the RAM, and the programs expanded into the RAM are executed by the CPU, thereby realizing the functions of each part in the inner surface shape measuring device 10, and various calculation processes and control processes are executed via the input/output interface.

As shown in FIG. 3, the control device 50 includes a measurement control unit 52, a displacement acquisition unit 54, a circularity calculation unit 56, an observation control unit 58, a position and tilt calculation unit 60, a stage control unit 62, and an output unit 63.

The measurement control unit 52 controls the motors (not shown) that are connected to the carriage 22, the arm 24, and the rotating body 14, respectively, and controls the relative position between the probe 30 of the displacement detector 28 and the fine hole H of the workpiece W.

The displacement acquisition unit 54 controls the displacement detector 28 and acquires the displacement of the hole wall of the fine hole H detected by the displacement detector 28.

The roundness calculation unit 56 calculates the roundness of the fine hole H from the relative position between the probe 30 and the workpiece W obtained from the measurement control unit 52 and the displacement detected by the displacement detector 28.

The observation control unit (first and second observation control units) 58 controls the camera 34 and acquires the images captured by the camera 34. The position and tilt calculation unit 60 calculates the position and tilt of the fine hole H in the workpiece W from the images acquired by the observation control unit 58. The stage control unit 62 controls a motor (not shown) that drives the linear tilt stage 16 based on the position and tilt of the fine hole H calculated by the position and tilt calculation unit 60, and changes the position and tilt of the linear tilt stage 16. The output unit 63 outputs the fine hole information including the position and tilt of the fine hole H acquired from the position and tilt calculation unit 60 to an output interface (not shown).

<Alignment method>
As described above, in order to measure the inner surface shape such as the roundness of the fine hole H in the workpiece W, alignment is required to make the central axis _AH of the fine hole H coincide with the rotation axis _AR of the rotor 14. Alignment includes centering, which adjusts the position within the XY plane, and tilting, which adjusts the inclination relative to the XY plane. The inner surface shape measuring machine 10 is capable of centering and tilting by the linear tilt stage 16.

4 is a flowchart showing an example of the process of the alignment method of the inner surface shape measuring machine 10. Here, it is assumed that a workpiece W having a small hole H is set in advance on the workpiece setting jig 18. The workpiece setting jig 18 fixes the workpiece W with a gap provided at a lower opening O _D (see FIG. 7 ) of the small hole H of the workpiece W (without closing the lower opening O _D ).

In step S1, the measurement control unit 52 drives a motor (not shown) in response to the detection result of an encoder (not shown) of the rotating body 14, and moves (rotates) the rotating body 14 to a position where the rotation angle is the set angle θ = 0° (an example of a first rotation angle).

In step S2, the measurement control unit 52 drives a motor (not shown) of the arm 24 to move the camera 34 upward in the Z direction of the workpiece W. In addition, the measurement control unit 52 drives a motor (not shown) of the carriage 22 to move the camera 34 in the Z direction, and adjusts the focal position of the camera 34 to an upper opening _OU (an example of the first position) of the fine hole H.

In the next step S3 (an example of an observation control step), the observation control unit 58 observes (photographs) the upper opening _OU of the fine hole H using the camera 34. Furthermore, the position and tilt calculation unit 60 calculates _{the center coordinates (x, y) OU of} the upper opening OU of the fine hole H at the set angle θ = 0°.

5 is a schematic diagram showing the observation of the upper opening _OU of the fine hole H by the camera 34. In FIG. 5, the workpiece W is shown in cross section. The focal plane _FU shown in FIG. 5 is a plane that is perpendicular to the optical axis _AC of the camera 34 and includes the focal point of the camera 34, and is aligned with the position of the upper opening _OU of the fine hole H here. The dot-hatched portion shown in FIG. 5 is the optical path of the observation light of the upper opening _OU incident on the camera 34, and the image _I0U shown in FIG. 5 is an image (viewed in the Z direction) of the edge portion of the upper opening _OU observed by the camera 34.

6 is a diagram showing the positional relationship between the rotation axis A _R of the rotor 14, the upper opening _OU of the fine hole H in the workpiece W when the set angle θ of the rotor 14 is 0°, the shooting range R of the camera 34, and the image I _0U observed in step S3 in the shooting range R. In FIG. 6, the shooting range R is shown as viewed in the Z direction, and the cross section of the workpiece W is shown as viewed in the Y direction.

The position and tilt calculation unit 60 calculates the central coordinates (x, y) _0U of the upper opening _OU of the fine hole H at the set angle θ=0° from the image I _0U .

Next, in step S4, the measurement control unit 52 drives a motor (not shown) of the carriage 22 to move the camera 34 in the Z direction and align the focal position of the camera 34 with a lower opening O _D (an example of a second position) that is positioned differently in the Z direction from the upper opening O _DU of the fine hole H.

In the next step S5 (an example of an observation control step), the observation control unit 58 observes the lower opening O _D of the fine hole H using the camera 34. Furthermore, the position and tilt calculation unit 60 calculates the center coordinates (x, y) _0D of the lower opening O _D of the fine hole H at the set angle θ = 0°.

Fig. 7 is a schematic diagram showing the observation of the lower opening _OD of the fine hole H by the camera 34. In Fig. 7, the workpiece W is shown in cross section. As shown in Fig. 7, the focal plane _FD is aligned with the position of the lower opening _OD of the fine hole H. The dot-hatched portion shown in Fig. 7 is the optical path of the observation light of the lower opening _OD incident on the camera 34, and the image _IOD shown in Fig. 7 is an image (viewed in the Z direction) of the edge portion of the lower opening _OD observed by the camera 34.

8 is a diagram showing the positional relationship between the rotation axis A _R of the rotor 14, the lower opening O _D of the fine hole H in the workpiece W when the set angle θ of the rotor 14 is 0°, and the image I _{0 D} observed in step S5 in the shooting range R of the camera 34. In Fig. 8, the shooting range R is shown as viewed in the Z direction, and the cross section of the workpiece W is shown as viewed in the Y direction.

The position and tilt calculation unit 60 calculates the center coordinates (x, y) _0D of the lower opening _OD of the fine hole H at the set angle θ=0° from the image I _0D .

Next, in step S6, the measurement control unit 52 drives a motor (not shown) in response to the detection result of an encoder (not shown) of the rotating body 14, and moves the rotating body 14 to a position where the rotation angle is the set angle θ = 180° (an example of a second rotation angle).

In step S7, the measurement control unit 52 drives a motor (not shown) of the carriage 22 to move the camera 34 in the Z direction, and adjusts the focal position of the camera 34 to the upper opening _OU .

In the subsequent step S8 (an example of an observation control step), the observation control unit 58 observes the upper opening _OU of the fine hole H using the camera _34. Furthermore, the position and tilt calculation unit 60 calculates the center coordinates (x, y) _180U of the upper opening _OU of the fine hole H at the set angle θ = 180° from the image I 180U.

9 is a diagram showing the positional relationship between the rotation axis A _R of the rotor 14, the upper opening _OU of the fine hole H in the workpiece W when the set angle θ of the rotor 14 is 180°, and the image I _0U observed in step S8 in the shooting range R of the camera 34. In FIG. 9, the shooting range R is shown as viewed in the Z direction, and the cross section of the workpiece W is shown as viewed in the Y direction.

The position and tilt calculation unit 60 calculates the center coordinates (x, y) _180U of the upper opening _OU of the fine hole H at the set angle θ=180° from the image I _180U .

Next, in step S9, the measurement control unit 52 drives a motor (not shown) of the carriage 22 to move the camera 34 in the Z direction and adjusts the focal position of the camera 34 to the lower opening _OD of the fine hole H.

In the next step S10 (an example of an observation control step), the observation control unit 58 observes the lower opening O _D of the fine hole H with the camera 34. Furthermore, the position and tilt calculation unit 60 calculates the center coordinates (x, y) 180D of the lower opening O _D of the fine hole H at the set angle θ = 180° from _the image I _180D .

10 is a diagram showing the positional relationship between the rotation axis A _R of the rotor 14, the lower opening O _D of the fine hole H in the workpiece W when the set angle θ of the rotor 14 is 180°, and the image I _{0 D} observed in step S10 in the shooting range R of the camera 34. In Fig. 10, the shooting range R is shown as viewed in the Z direction, and the cross section of the workpiece W is shown as viewed in the Y direction.

The position and tilt calculation unit 60 calculates the center coordinates (x, y) _180D of the lower opening O _D of the fine hole H at the set angle θ=180° from the image I _180D .

In step S11 (an example of a position and inclination calculation process), the position and inclination calculation unit 60 calculates the position and inclination of the central axis AH of the fine hole H in the workpiece _W relative to the rotation axis AR of the rotating body 14 from the central coordinates (x, y) _0U of the upper opening _OU and the central coordinates (x, _y ) _0D of the lower opening OD of the fine hole H at the set angle _θ = 0°, and the central coordinates (x, y) _180U of the upper opening _OU and the central coordinates (x, y) _180D of the lower opening OD of the fine hole H at the set angle _θ = 180°.

In step S12, the position and inclination calculation unit 60 judges whether the deviation between the position and inclination of the central axis _AH of the fine hole H in the workpiece W and the rotation axis _AR is within a target value. If the deviation is greater than the target value, the control device 50 performs the process of step S13. If the deviation is within the target value, the process of this flowchart ends.

In step S13, the position and tilt calculation unit 60 calculates the movement amount of the linear motion tilt stage 16. Fig. 11 is a diagram for explaining the movement target coordinates C _U (x, y) of the upper opening _OU and the movement target coordinates C _D (x, y) of the lower opening _OD . Fig. 11 shows the positional relationship between the center coordinates (x, y) _0U of the upper opening _OU and the center coordinates (x, y) _0D of the lower opening _OD at the set angle θ = 0°, the center coordinates (x, y) _180U of the upper opening _OU and the center coordinates (x, y) _180D of the lower opening _OD at the set angle θ = 180°, the movement target coordinates C _U (x, y) of the upper opening _OU , and the movement target coordinates C _D (x, y) of the lower opening _OD .

As shown in FIG. 11, the movement target coordinates C _U (x, y) of the upper opening O _U are expressed as follows:
C _U (x, y)={(x, y) _0U + (x, y) _180U }/2...(Formula 1)
Similarly, the movement target coordinates C _D (x, y) of the lower opening O _D can be expressed as follows:
C _D (x, y) = {(x, y) _0D + (x, y) _180D }/2 ... (Formula 2)
It can be expressed as:

The position and tilt calculation unit 60 calculates the amount of movement of the linear motion tilt stage 16 from the movement target coordinates C _U (x, y) of the upper opening _OU and the movement target coordinates C _D (x, y) of the lower opening _OD . The output unit 63 acquires the amount of movement of the linear motion tilt stage 16 calculated by the position and tilt calculation unit 60 (an example of fine hole information), and outputs it to the stage control unit 62 (an example of an output process).

In step S14 (an example of a stage control step), the stage control unit 62 drives a motor (not shown) of the linear motion tilt stage 16 based on the amount of movement calculated in step S13, and moves the linear motion tilt stage 16 to a target position. Then, the process proceeds to step S1, and the control device 50 performs the same process. By repeating this process, the inner surface shape measuring machine 10 keeps the deviation between the central axis _AH of the fine hole H in the workpiece W and the rotation axis _AR of the rotor 14 within a target value.

Thus, according to the alignment method of this embodiment, the central axis _AH of the fine hole H can be aligned with the rotation axis _AR of the rotating body 14. According to this embodiment, since it is not necessary to match the optical axis _AC of the camera 34 with the rotation axis _AR of the rotating body 14, alignment can be achieved with a simple configuration. The alignment method of this embodiment is effective when the fine hole H is a very small diameter hole with an inner diameter of 500 μm or less. Furthermore, it is particularly effective when the diameter of the fine hole H is 200 μm or less and the diameter of the probe 30 is 100 μm or less. Note that the fine hole H may have a diameter larger than 500 μm.

Here, the set angle θ of the rotation angle of the rotating body 14 when observing the upper opening _OU and the lower opening _OD with the camera 34 is set to θ = 0° and θ = 180°, which are angles that differ from each other by 180°, so that the deviation between the central axis _AH of the fine hole H in the workpiece W and the rotation axis _AR can be calculated with high accuracy.

In addition, in order for the inner surface shape measuring machine 10 to measure the cylindricity of the workpiece W with high accuracy, the column 20 is erected parallel to the rotation axis A _R of the rotor 14. In this embodiment, when switching between observing the upper opening _OU and the lower opening _OD of the fine hole H, the focal position of the camera 34 is moved by utilizing the vertical linear motion mechanism of the carriage 22. Therefore, a focus control mechanism for the camera 34 is not required, and high-precision alignment is possible. For example, since the rotation axis position in the focal plane does not move, it is possible to employ a high-magnification optical system.

The output unit 63 may also output the movement amount (one example of fine hole information) of the linear motion tilt stage 16 acquired from the position tilt calculation unit 60 to an output interface (one example of an output process) not shown. The output unit 63 may also acquire fine hole information including the position and tilt of the central axis AH of the fine hole _H of the workpiece W relative to the rotation axis _AR of the rotating body 14 calculated in step S11, and output the information to an output interface (one example of an output process) not shown. The user can align the central axis _AH of the fine hole H of the workpiece W with the rotation axis _AR of the rotating body 14 by manually operating the linear motion tilt stage 16 based on the output information. In this embodiment, the output unit 63 outputs the acquired movement amount to the stage control unit 62.

<Workpiece installation jig>
In order to observe the lower opening _OD of the fine hole H, it is necessary to keep the angle (inclination) of the fine hole H within a certain range when the work W is placed on the work placement jig 18.

Fig. 12 is a diagram showing the relationship between the camera and the fine hole in the workpiece due to the workpiece installation jig. 212A in Fig. 12 shows the maximum angle of the observation light incident on the objective lens (not shown) of the camera 34 with respect to the optical axis A _C. As shown in 212A, if the numerical aperture of the objective lens of the camera 34 is NA, the maximum angle θ _obj of the observation light incident on the objective lens with respect to the optical axis A _C of the camera 34, and the refractive index of the optical path of the observation light is n, then
NA=n×sinθ _obj …(Formula 3)
Therefore, assuming that the refractive index n of the air in the optical path of the observation light is 1.0, and the inclination angle of the fine hole H with respect to the rotation axis A _R of the rotor 14 is θ _work ,
θ _work <asin(NA) (Formula 4)
A workpiece setting jig 18 capable of positioning the workpiece W so as to satisfy the above is required.

12 shows the relationship between the camera 34 and the workpiece W when the relationship θ _work <θ _obj is satisfied. In 212B, the workpiece W is shown in cross section. The optical path P shown in 212B is an optical path that can be used to observe the lower opening _OD among the optical paths of the observation light incident on the camera 34. In this way, in the case shown in 212B, it is possible to observe the lower opening _OD with the camera 34.

12 shows the relationship between the camera 34 and the workpiece W when θ _work >θ _obj . In 212C, the workpiece W is shown in cross section. In the case shown in 212C, the observation light from the lower opening O _D does not reach the camera 34, and the camera 34 cannot observe the lower opening O _D.

<Position to observe fine holes>
In the above example, the upper opening _ODU and the lower opening _OD of the fine hole H are observed. However, the position at which the fine hole H is observed is not limited to the opening, and may be a midway position of the fine hole H.

13 is a schematic diagram showing observation by the camera 34 of an intermediate position O _H (an example of a second position) that is different in the Z direction from the upper opening O _DU and the lower opening O _D of the fine hole H. In FIG. 13, the workpiece W is shown in cross section. The fine hole H shown in FIG. 13 has an R at the edge of the lower opening O _D (the lower opening O _D has an R shape). For this reason, in the example shown in FIG. 13, the focal plane F _H is aligned with the intermediate position O _H of the fine hole H. In addition, the dot-hatched portion shown in FIG. 13 is the optical path of the observation light at the intermediate position O _H that enters the camera 34, and the image I _OH shown in FIG. 13 is an image (viewed in the Z direction) of the intermediate position O _H observed by the camera 34.

In this way, when the upper opening _ODU or the lower opening _OD of the fine hole H has a chamfer or a radius, making it difficult to observe the edge shape of the fine hole H, it is effective to observe a midway position of the fine hole H. When using a midway position of the fine hole H, a method of selecting a high-contrast (in-focus) area in the image or measurement using a white light interference method can be used to detect the position of the fine hole H.

<When the position of the fine hole is significantly offset from the rotation axis>
In the above example, when the rotating body 14 was rotated, the fine hole H was always within the shooting range of the camera 34 fixed in the X direction. In other words, the fine hole H was originally positioned at a position close enough to the rotation axis A _R of the rotating body 14 that it was within the shooting range of the camera 34. However, even if the fine hole H is positioned significantly deviated from the rotation axis A _R of the rotating body 14, a similar method can be applied by operating the horizontal linear motion mechanism.

FIG. 14 is a schematic diagram showing, in time series, observation of the small hole H by the camera 34 in a case where the small hole H in the workpiece W is positioned significantly offset from the rotation axis A _R of the rotor 14.

14 shows a state where the fine hole H in the workpiece W is not within the shooting range of the camera 34. Here, the measurement control unit 52 moves the rotating body 14 to a position where the rotation angle is set angle θ= _θA . The set angle θ= _θA is the angle at which the fine hole H in the workpiece W and the arm 24 overlap when viewed in the Z direction. The movement to the position of set angle θ= _θA may be performed by positioning with a jig, or the rotating body 14 may be moved at each position of the camera 34 by the movement of the arm 24, and the fine hole H may be searched for by the camera 34.

14 shows the state in which the observation control unit 58 moves the arm 24, which is a horizontal linear motion mechanism, to position _PA where the fine hole H comes into the field of view of the camera 34. At this position _PA , the observation control unit 58 observes the upper opening _OU and lower opening _OD of the fine hole H with the camera 34. Furthermore, the position and tilt calculation unit 60 calculates the center coordinates (x, y) _AU of the upper opening _OU and the center coordinates (x, y) _AD of the lower opening _OD of the fine hole H at the set angle θ= _θA . Furthermore, the position and tilt calculation unit 60 stores the position _PA of the arm 24.

14C shows the state where the measurement control unit 52 moves the rotor 14 to a position where the rotation angle is the set angle θ=θ _A +180°=θ _B.

14 shows the state in which the observation control unit 58 moves the arm 24, which is a horizontal linear motion mechanism, to position P _B where the fine hole H comes into the field of view of the camera 34. At this position P _B , the observation control unit 58 observes the upper opening _OU and lower opening _OD of the fine hole H with the camera 34. Furthermore, the position and tilt calculation unit 60 calculates the center coordinates (x, y) _BU of the upper opening _OU and the center coordinates (x, y) _BD of the lower opening _OD of the fine hole H at the set angle _θ = θ B. Furthermore, the position and tilt calculation unit 60 stores the position P _B of the arm 24.

From the central coordinates (x, y) _AU of the upper opening _OU of the fine hole _H , the central coordinates (x, y) _AD of the lower opening _OD , and the position _PA of the arm 24 at the set angle θ = _θA , and the central coordinates (x, y) _BU of the upper opening _OU of the fine hole H, the central coordinates (x, y) _BD of the lower opening _OD , and the position PB of the arm 24 at the set angle θ = _θB , the position and inclination calculation unit 60 can calculate the position and inclination of the fine hole H in the workpiece W relative to the rotation axis A _R of the rotating body 14.

<Another example of calculating the position and inclination of a fine hole>
In the above example, an example in which observation is performed at two rotation angles has been shown, but the rotation angle of the rotor 14 may be set to three or more angles, or may be set continuously. For example, the position and inclination of the fine hole H may be calculated from the locus of the central coordinates.

15 is a diagram showing a trajectory _TU of the central coordinates of the upper opening _OU of the fine hole H in the imaging range R of the camera 34 when the rotating body 14 is rotated. Here, the trajectory is shown when the rotation angle of the rotating body 14 is rotated from the set angle θ=0° to the set angle θ=90°. The position and tilt calculation unit 60 calculates the central coordinates (x,y) _0U , (x,y) _15U , (x,y) _30U , (x,y) _45U , (x,y) _60U , (x,y)75U, (x,y)90U of the set angles θ=0°, 15°, 30°, _45° , _60° , 75°, and _90° from this trajectory TU, and calculates the movement target coordinates, i.e., the coordinates of the rotation axis A _R , from the calculated central coordinates.

In this way, calculations can be performed without rotating the rotating body 14 180 degrees, which allows for faster alignment. In addition, since a large amount of information is available when determining the center of rotation, it is possible to calculate the movement target coordinates with high accuracy.

<Light intensity adjustment>
Fig. 16 is a diagram showing the optical path of the observation light of the lower opening of the fine hole of the workpiece that enters the camera. 216A in Fig. 16 shows the optical path of the observation light of the lower opening _OD of the fine hole H of the workpiece W that enters the camera 34. In 216A, the workpiece W is shown in cross section. As shown in 216A, the optical path that can be used for observing the lower opening _OD has a small amount of light. That is, the observation of the lower opening _OD may be difficult due to insufficient light compared to the observation of the upper opening _OU . Therefore, a mechanism may be provided to increase the amount of light when observing the lower opening _OD compared to when observing the upper opening _OU .

216B in FIG. 16 shows a state where the light source 70 is arranged on the lower opening O _D side to irradiate the fine hole H. In 216B, the workpiece W is shown in cross section. The light source 70 irradiates the fine hole H from the lower opening O _D (an example of an opening on the linear tilt stage side). The light source 70 is preferably a low coherence light source in order to reduce speckle noise. For example, an LED (Light Emitting Diode) or an ASE (Amplified Spontaneous Emission) light source can be used as the light source 70. It is more preferable that the center of the light source 70 coincides with the rotation axis A _R of the rotating body 14.

In this way, by arranging the light source on the lower opening _OD side, the geometric edge of the lower opening _OD can be emphasized, making it easier to observe the lower opening _OD and enabling more accurate alignment.

<Inserting a reflector>
Depending on the shape of the workpiece W, it may be difficult to observe the lower opening _OD . Fig. 17 is a diagram showing the state of observation of the lower opening _OD of the fine hole H of the workpiece W by the camera 34. Fig. 17 shows the workpiece W in cross section. In the workpiece W shown in Fig. 17, other parts of the workpiece W are arranged on the lower opening _OD side of the fine hole H asymmetrically with respect to the center of the lower opening _OD . For this reason, as shown by 217A in Fig. 17, the amount of reflected light varies depending on the position of the lower opening _OD of the workpiece W, making it difficult to observe the lower opening _OD .

17, the workpiece W has a narrow space on the lower opening _OD side of the small hole H. Therefore, as shown by 217B in FIG. 17, there is insufficient space to insert the light source 70, and the light source 70 cannot be disposed on the lower opening _OD side.

Also, as shown in 217C of Fig. 17, it is possible to insert the reflector 72 into the lower opening O _D side. However, since the space on the lower opening O _D side is narrow, precise positioning is required. Also, there is a possibility that the reflector 72 and the workpiece W may collide with each other, damaging the workpiece W.

To address this issue, a flexible reflector may be inserted into the lower opening _OD side of the fine hole H in the workpiece W to increase the amount of light when observing the lower opening _OD .

Fig. 18 is a diagram showing the insertion of a sponge-like reflector 80 into the lower opening _OD side of a fine hole H in a workpiece W. Fig. 18 shows a cross section of the workpiece W. 218A in Fig. 18 shows the sponge-like reflector 80 before insertion, and 218B in Fig. 18 shows the sponge-like reflector 80 after insertion.

The sponge-like reflector 80 is a light reflecting member having elasticity and flexibility. The sponge-like reflector 80 reflects light incident from an upper opening _OU (an example of an opening on the camera side) of the fine hole H to the fine hole H at the lower opening _OD side (an example of the linear motion tilt stage side). It is desirable for the sponge-like reflector 80 to have a color such as white that has a high light reflectance. Since the sponge-like reflector 80 is flexible, it can be inserted into a narrow space on the lower opening _OD side.

By inserting such a sponge-like reflector 80 into the lower opening _OD , the amount of light when observing the lower opening _OD can be increased, making it easier to observe the lower opening _OD and enabling more accurate alignment. In addition, the sponge-like reflector 80 deforms to fit the shape of the workpiece W on the lower opening _OD side, which eliminates the need for strict shape forming and positioning, and thus provides the advantage of being low cost. Furthermore, the sponge-like reflector 80 has the advantage of being flexible and therefore does not damage the workpiece W.

Moreover, Fig. 19 is a diagram showing the insertion of the clay-like reflector 82 into the lower opening _OD side of the fine hole H of the workpiece W. Fig. 19 shows a cross section of the workpiece W. 219A in Fig. 19 shows the clay-like reflector 82 before insertion, and 219B in Fig. 19 shows the clay-like reflector 82 after insertion.

The clay-like reflector 82 is a light reflecting member having plasticity and flexibility. The clay-like reflector 82 reflects light incident from an upper opening _OU (an example of an opening on the camera side) of the fine hole H to the fine hole H at a lower opening _OD (an example of an opening on the linear tilt stage side). It is desirable for the clay-like reflector 82 to have a color such as white that has a high light reflectance. Since the clay-like reflector 82 is flexible, it can be inserted into a narrow space on the lower opening _OD side.

By inserting such a clay-like reflector 82 into the lower opening _OD , the amount of light during observation of the lower opening _OD can be increased, making it easier to observe the lower opening _OD and enabling more accurate alignment. In addition, the clay-like reflector 82 deforms to conform to the shape of the workpiece W on the lower opening _OD side, which has the effect of eliminating the need for strict shape forming and positioning, and thus reducing costs. Furthermore, the clay-like reflector 82 has the effect of eliminating the concern that it will damage the workpiece W because it is flexible.

Furthermore, Fig. 20 is a diagram showing the insertion of the scatterer 84 into the lower opening _OD side of the fine hole H in the workpiece W. Fig. 20 shows a cross section of the workpiece W. 220A in Fig. 20 shows the scatterer 84 before insertion, and 220B in Fig. 20 shows the scatterer 84 after insertion.

The scatterer 84 is a sponge with an open-cell structure that has elasticity and flexibility. The scatterer 84 is placed on the lower opening _OD side (an example of the side opposite to the camera side) of the fine hole H. Since the scatterer 84 is flexible, it can be inserted into the narrow space on the lower opening _OD side. The light source 70 is attached to the scatterer 84. The light source 70 causes light to enter the scatterer 84. The light that enters the scatterer 84 from the light source 70 is multiple-scattered inside the scatterer 84 and enters the lower opening _OD .

By disposing such a scatterer 84 on the lower opening _OD side, the scatterer 84 can form a surface light source by multiple scattering. Therefore, the amount of light when observing the lower opening _OD can be increased, making it easier to observe the lower opening _OD and enabling more accurate alignment. In addition, since the scatterer 84 deforms according to the shape of the workpiece W on the lower opening _OD side, there is an effect that strict shape forming and positioning are not required, and low cost is achieved. Furthermore, since the scatterer 84 is flexible, there is an effect that there is no concern that the workpiece W will be damaged.

Another embodiment
In the above embodiment, an example has been described in which the position and inclination of the fine hole H are calculated each time the inner shape of the workpiece W is measured. However, it is also possible to register the position of the rotation axis A _R of the rotating body 14 (see FIG. 15 ; hereinafter, also referred to as the rotation center coordinate) in advance and align the workpiece W using the registered rotation center coordinate.

Figure 21 is a flowchart showing the process of an alignment method for an inner surface shape measuring machine according to another embodiment of the present invention.

As shown in FIG. 21, in this embodiment, the position (rotation center coordinates) of the rotation axis A 2 _R of the rotating body 14 is measured and registered using a reference workpiece W 2 _R (step S100).

Next, the workpiece W, which is the object to be measured, is aligned using the rotation center coordinates registered in step S100 (step S200), and the workpiece W is measured (step S300). Steps S200 to S300 are then repeated until measurements of all of the workpieces W have been completed (step S400).

Next, the process of registering the position of the rotation center coordinates (step S100) in this embodiment will be described with reference to FIG. 22.

First, in step S102, a reference workpiece W _R is placed on the workpiece setting jig 18. Here, the reference workpiece W _R has a shape (one example of a hole pattern) equivalent to a fine hole (e.g., circular) like the workpiece W to be measured, and is a workpiece whose shape (e.g., outer diameter dimension and hole dimension, etc.) has been accurately measured and known in advance. The reference workpiece W _R can be, for example, one made of the same material as the workpiece W to be measured and having approximately the same shape.

Next, in step S104, the measurement control unit 52 drives a motor (not shown) in response to the detection result of an encoder (not shown) of the rotating body 14, and moves (rotates) the rotating body 14 to a position where the rotation angle is the set angle θ = 0° (an example of a first rotation angle).

In step S106, the measurement control unit 52 drives a motor (not shown) of the arm 24 to move the camera 34 upward in the Z direction of the reference workpiece W _R. The measurement control unit 52 also drives a motor (not shown) of the carriage 22 to move the camera 34 in the Z direction, and adjusts the focal position of the camera 34 to an upper opening O _U of the fine hole H (an example of the first position).

In the subsequent step S108 (an example of a first observation control step), the observation control unit 58 observes (photographs) the upper opening _OU of the fine hole H using the camera 34. Furthermore, the position and tilt calculation unit 60 calculates the center _{coordinates (x, y) OU of} the upper opening OU of the fine hole H at the set angle θ = 0°.

Next, in step S110, the measurement control unit 52 drives a motor (not shown) of the carriage 22 to move the camera 34 in the Z direction and align the focal position of the camera 34 with a lower opening O _D (an example of a second position) that is positioned differently in the Z direction from the upper opening O _DU of the fine hole H.

In the subsequent step S112 (an example of a first observation control step), the observation control unit 58 observes the lower opening O _D of the fine hole H with the camera 34. Furthermore, the position and tilt calculation unit 60 calculates the center coordinates (x, y) _0D of the lower opening O _D of the fine hole H at the set angle θ = 0°.

Next, in step S114, the measurement control unit 52 drives a motor (not shown) in response to the detection result of an encoder (not shown) of the rotating body 14, and moves the rotating body 14 to a position where the rotation angle is the set angle θ = 180° (an example of the second rotation angle).

In step S116, the measurement control unit 52 drives a motor (not shown) of the carriage 22 to move the camera 34 in the Z direction, and adjusts the focal position of the camera 34 to the upper opening _OU .

In the subsequent step S118 (an example of a first observation control step), the observation control unit 58 observes the upper opening _OU of the fine hole H using the camera _34. Furthermore, the position and tilt calculation unit 60 calculates the center coordinates (x, y) _180U of the upper opening _OU of the fine hole H at the set angle θ = 180° from the image I 180U.

Next, in step S120, the measurement control unit 52 drives a motor (not shown) of the carriage 22 to move the camera 34 in the Z direction and adjusts the focal position of the camera 34 to the lower opening _OD of the fine hole H.

In the subsequent step S122 (an example of a first observation control step), the observation control unit 58 observes the lower opening O _D of the fine hole H with the camera 34. Furthermore, the position and tilt calculation unit 60 calculates the center coordinates (x, y) _180D of the lower opening O _D of the fine hole H at the set angle θ = 180° from the _{image I 180D} .

In step S124 (an example of a rotation center coordinate calculation process), the position and tilt calculation unit 60 calculates the position (rotation center coordinate) of the rotation axis A _R of the rotating body 14 from the center coordinates (x, y) _0U of the upper opening _OU and the center coordinates (x, y) _0D of the lower opening _OD of the fine hole H at the set angle θ = 0°, and the center coordinates (x, y) _180U of the upper opening _OU and the center coordinates (x, y) _180D of the lower opening OD of the fine hole _H at the set angle θ = 180°. Then, in step S126, the position and tilt calculation unit 60 stores the rotation center coordinates calculated in step S124 in the storage of the control device 50.

Next, the alignment process for the workpiece W, which is the object to be measured, will be explained with reference to Figure 23.

First, in step S202, the workpiece W to be measured is placed on the workpiece placement jig 18.

In step S204, the measurement control unit 52 drives a motor (not shown) of the arm 24 to move the camera 34 upward in the Z direction of the workpiece W. In addition, the measurement control unit 52 drives a motor (not shown) of the carriage 22 to move the camera 34 in the Z direction, and adjusts the focal position of the camera 34 to an upper opening _OU of the fine hole H (an example of the third position).

In the subsequent step S206 (an example of a second observation control step), the observation control unit 58 observes (photographs) the upper opening _OU of the fine hole H using the camera 34. Furthermore, the position and tilt calculation unit 60 calculates the center coordinates (x, y) _U of the upper opening _OU of the fine hole H.

Next, in step S208, the measurement control unit 52 drives a motor (not shown) of the carriage 22 to move the camera 34 in the Z direction and align the focal position of the camera 34 with a lower opening O _D (an example of the fourth position) that is positioned differently in the Z direction from the upper opening O _DU of the fine hole H.

In the next step S210 (an example of a second observation control step), the observation control unit 58 observes the lower opening O _D of the small hole H with the camera 34. Furthermore, the position and tilt calculation unit 60 calculates the center coordinates (x, y) _D of the lower opening O _D of the small hole H.

In step S212 (an example of a position and inclination calculation process), first, the position and inclination calculation unit 60 calculates the position and inclination of the central axis AH of the fine hole H of the workpiece W from the central coordinates (x, y) _U of the upper opening _OU and the central coordinates (x, y) _D of the lower opening _OD of the fine hole _H calculated in steps S206 and S210, respectively. Next, the position and inclination calculation unit 60 reads out the position (rotation center coordinates) of the rotation axis _AR of the rotating body 14 calculated in step S124 of FIG. 22 from the storage of the control device 50, and calculates the position and inclination of the central axis _AH of the fine hole H of the reference workpiece _WR relative to the position (rotation center coordinates) of the rotation axis _AR of the rotating body 14. Here, the position and inclination calculation unit 60 functions as a rotation center coordinate calculation unit.

In step S214, the position and inclination calculation unit 60 judges whether the deviation between the position and inclination of the central axis _AH of the fine hole H in the workpiece W and the rotation axis _AR is within a target value. If the deviation is greater than the target value, the control device 50 performs the process of step S216. If the deviation is within the target value, the process of this flowchart ends.

In step S216, the position and tilt calculation unit 60 calculates the amount of movement of the linear tilt stage 16.

In step S218 (an example of a stage control step), the stage control unit 62 drives a motor (not shown) of the linear motion tilt stage 16 based on the amount of movement calculated in step S13 to move the linear motion tilt stage 16 to a target position. Then, the process proceeds to step S204, and the control device 50 performs the same process. By repeating this process, the inner surface shape measuring machine 10 keeps the deviation between the central axis _AH of the fine hole H in the workpiece W and the rotation axis _AR of the rotor 14 within a target value.

According to this embodiment, it is not necessary to operate the rotating body 14 each time alignment of the workpiece W, which is the object to be measured, is performed (see FIG. 23). Therefore, alignment of the workpiece W can be completed in a short time.

Generally, the driving-in operation needs to be repeated multiple times to bring the deviation between the central axis _AH of the fine hole H in the workpiece W and the rotation axis _AR of the rotor 14 within a target value (see Figs. 4 and 23). The higher the target alignment accuracy is (the smaller the target deviation value is), the more times the repetitions tend to be required.

In this embodiment, the driving motion does not include the movement of the rotating body 14, so the required time can be significantly reduced.

As a specific example, the number of times the driving operation is repeated is N, and in one example, N = 4 times on average. In addition, the time required for the rotation of the rotor 14 in one driving operation (rotation from θ = 0° to θ = 180°) is t1. If the rotation of the rotor 14 takes 30 seconds for each of the upper and lower openings, then t1 = 30 seconds x 2 = 60 seconds. The time required for positioning the camera's focal position up and down, taking pictures, and moving the axis is t2, and in one example, t2 = 30 seconds. In this case, the times T1 and T2 required for alignment when the driving operation includes the movement of the rotor 14 (Figure 4) and when it does not (Figure 23) are as follows:

T1 = (t1 + t2) x N = (60 + 30) x 4 = 360 seconds T2 = t2 x N = 30 x 4 = 120 seconds In the above specific example, when the operation of the rotating body 14 is not included in the driving operation, it is possible to dramatically reduce the time required for aligning the workpiece W to one-third, compared to when it is included.

Furthermore, according to this embodiment, since the shape and dimensions of the reference workpiece W _R are known, the rotation center coordinates can be calculated with high accuracy. Generally, the hole in the workpiece W, which is the object to be measured, is not limited to a circular shape, and may be a distorted circular shape such as an ellipse, or a shape with a protrusion inside. When calculating the rotation center coordinates in the captured image based on the shape of the fine hole in the workpiece W, which is the object to be measured, it may be difficult to calculate the rotation center with high accuracy due to the influence of the shape of the fine hole in the workpiece W.

FIG. 24 is a plan view showing an example of calculation of the rotation center coordinate when the fine hole H of the workpiece W has a shape with a protrusion inside, and FIG. 25 is a plan view showing an example of calculation of the rotation center coordinate using a reference workpiece W _R.

In the example shown in Figure 24, when θ = 0°, the protrusion _P0 of the fine hole _H10 is clearly visible. Therefore, the center position of the fine hole _H10 is detected as a position _C1ERR, which is shifted from the true position C1 to the opposite side of the protrusion _P0 . On the other hand, when θ = 180°, the protrusion _P180 of the fine hole _H1180 is crushed due to the influence of lighting, etc. Therefore, the center position of the fine hole _H1180 is detected as a position C2 that approximately coincides with the center of the circle. Therefore, in this example, the rotation center coordinates are detected as a position _C0ERR, which is shifted from the true position C0.

On the other hand, in the example shown in Fig. 25, in both cases of θ = 0° and θ = 180°, the fine holes H _R0 and H _R180 are both known perfect circular shapes, so that the shape of the fine holes can be detected without being affected by lighting, etc. Therefore, the center CR1 of the fine holes H _R0 and the center CR2 of the fine holes H _R180 can be accurately detected, and the calculation accuracy of the rotation center coordinate C can be improved. Also, by measuring shape information such as the circle diameter of the fine holes in the reference workpiece W _R in advance and using this shape information to detect the fine holes and calculate the center coordinates, the rotation center coordinate C can be calculated with higher accuracy.

(Regarding standard workpiece _WR )
In the above-mentioned other embodiment, the reference work W R has a three-dimensional shape having a fine hole similar to the work W to be measured, but the present invention is not limited to this. For example, a planar work W _R may be used as the reference work W _R. The planar reference work W _R may have a black circular pattern (an example of a hole-shaped pattern) corresponding to the fine hole. In this case, it becomes possible to share a program for searching and calculating the position of the fine hole with the above-mentioned embodiment. In addition, the planar reference work W _R may have a printed pattern for positioning (a reticle, an example of a hole-shaped pattern) printed thereon (for example, see the planar reference work W _R1 in FIG. 26). The printed pattern for positioning may have a pattern indicating the center position of the fine hole. In this case, it becomes possible to perform calculations of the rotation center coordinates and the like with high accuracy.

Furthermore, when a planar reference workpiece is used, it is possible to use it in conjunction with a mechanism for moving the reference workpiece up and down in the Z direction. In this case, as shown in Fig. 26, by moving a planar reference workpiece W _R1 up and down in the Z direction, the rotation center coordinates are calculated based on the center C _R1 of the reticle (pattern Pa) for each position in the Z direction. This allows the inclination of the rotation axis to be calculated and registered in advance, thereby achieving more accurate alignment.

When a reference workpiece W _R having a three-dimensional shape (hole shape) is used, as described above, the program for searching and calculating the position of the fine hole can be shared with the case where a flat reference workpiece W _R is used. Furthermore, by registering the rotation center for each of the upper opening and the lower opening, the inclination of the rotation axis can also be calculated and registered in advance.

Also, the reference workpiece W _R can be a workpiece W, which is a measurement object made with high precision, or an object having a shape similar to that of the workpiece W. In this case, the gripping mechanism for the workpiece W, which is a measurement object, can be used to grip the reference workpiece W _R.

＜Other＞
The technical scope of the present invention is not limited to the scope described in the above embodiments. The configurations and the like in each embodiment can be appropriately combined with each other without departing from the spirit of the present invention.

LIST OF SYMBOLS 10...Inner surface shape measuring machine 12...Main body base 14...Rotating body 16...Linear tilt stage 18...Workpiece installation jig 20...Column 22...Carriage 24...Arm 28...Displacement detector 30...Probe 34...Camera 35...Coaxial epi-illumination optical system 38...Optical fiber 40...Reflecting mirror 42...Contactor 50...Control device 52...Measurement control unit 54...Displacement acquisition unit 56...Circularity calculation unit 58...Observation control unit 60...Position and tilt calculation unit 62...Stage control unit 63...Output unit 70...Light source 72...Reflector 80...Sponge-like reflector 82...Clay-like reflector 84...Scattering body _AH ...Central axis _AR ...Rotation axis _FD ...Focal plane _FU ...Focal plane H...Slim hole _I0D ...Image _I0U ...Image _I180D ...Image _I180U ...Image _OD ...Lower opening _OU ...Upper opening P...Optical path R...Photographing range S1 to S14...Each step of the process of the alignment method of the inner surface shape measuring machine _TU ...Trajectory of the center coordinates of the upper opening W...Workpiece _WR , _WR1 ...Reference workpiece

Claims (8)

a rotor that rotates about a rotation axis parallel to a first direction;
a linear motion tilt stage supported by the rotating body, the linear motion tilt stage being capable of changing a position in a plane perpendicular to the first direction with respect to the rotating body and a tilt with respect to the plane;
a displacement detector that detects a displacement of an inner surface of a small hole in a workpiece that is fixed to the linear motion tilt stage and rotates together with the rotating body, the displacement detector being a contact or non-contact probe extending parallel to the first direction and movable in the first direction by a first linear motion mechanism;
a camera having an optical axis parallel to the first direction;
a first observation control unit that observes, with respect to a reference workpiece having a known shape and having a hole pattern formed thereon, a first position of the hole pattern of the reference workpiece at a first rotation angle of the rotating body and a second position that is different in the first direction from the first position, and the first position and the second position of the hole pattern of the reference workpiece at a second rotation angle that is different from the first rotation angle of the rotating body, using the camera;
a rotation center coordinate calculation unit that calculates rotation center coordinates of the rotating body from the coordinates of the first position and the second position of the fine hole at the first rotation angle of the rotating body observed and the coordinates of the first position and the second position of the fine hole at the second rotation angle of the rotating body;
a second observation control unit that observes a third position of the fine hole of the workpiece to be measured fixed to the linear motion tilt stage and a fourth position that is different in the first direction from the third position by a camera having an optical axis parallel to the first direction;
a position and inclination calculation unit that calculates a position and an inclination of the fine hole from the rotation center coordinates of the rotating body and the third position and the fourth position of the fine hole of the rotating body;
An inner surface shape measuring machine equipped with The inner surface shape measuring machine according to claim 1, further comprising a stage control unit that controls the linear tilt stage based on fine hole information including the position and tilt of the fine hole, and adjusts the deviation between the center axis of the fine hole and the rotation axis to within a target value. the camera is movable in the first direction by the first linear motion mechanism;
3. The inner surface shape measuring instrument according to claim 1, wherein the second observation control section moves a focal position of the camera to the third position and the fourth position of the fine hole by the first linear motion mechanism. The inner surface shape measuring machine according to any one of claims 1 to 3, wherein the first rotation angle and the second rotation angle are different from each other by 180°. The inner surface shape measuring instrument according to any one of claims 1 to 4, which is equipped with a coaxial illumination optical system that emits light coaxially with the optical axis of the camera. A sponge-like or clay-like reflector is provided,
6. The inner surface shape measuring machine according to claim 5, wherein the reflector reflects light incident from an opening of the fine hole in the workpiece arranged between the camera and the linear motion tilt stage onto the fine hole on the linear motion tilt stage side. A flexible open-cell structure;
a light source that causes light to be incident on the open cell structure;
Equipped with
6. The inner surface shape measuring instrument according to claim 1, wherein the open cell structure allows light from the light source to be incident through an opening of the small hole in the workpiece arranged between the camera and the linear motion tilt stage on the linear motion tilt stage side. a rotor that rotates about a rotation axis parallel to a first direction;
a linear motion tilt stage supported by the rotating body, the linear motion tilt stage being capable of changing a position in a plane perpendicular to the first direction with respect to the rotating body and a tilt with respect to the plane;
a displacement detector that detects a displacement of an inner surface of a small hole in a workpiece to be measured, the workpiece being fixed to the linear motion tilt stage and rotating together with the rotating body, by using a contact or non-contact probe that extends parallel to the first direction and is movable in the first direction by a first linear motion mechanism;
An alignment method for an inner surface shape measuring machine comprising:
a first observation control process for fixing a reference workpiece having a known shape and on which a hole pattern is formed to the linear inclination stage, and observing a first position of the hole pattern of the reference workpiece at a first rotation angle of the rotating body and a second position different in the first direction from the first position, and the first position and the second position of the hole pattern of the reference workpiece at a second rotation angle different from the first rotation angle of the rotating body, using a camera having an optical axis parallel to the first direction;
a rotation center coordinate calculation step of calculating a rotation center coordinate of the rotating body from the coordinates of the first position and the second position of the fine hole at the first rotation angle of the rotating body observed and the coordinates of the first position and the second position of the fine hole at the second rotation angle of the rotating body;
a second observation control step of fixing the workpiece to be measured to the linear tilt stage and observing a third position of the small hole of the workpiece to be measured and a fourth position, which is a position in the first direction different from the third position, by a camera having an optical axis parallel to the first direction;
a position and inclination calculation step of calculating a position and an inclination of the fine hole from the rotation center coordinates of the rotating body and the third position and the fourth position of the fine hole of the rotating body;
An alignment method for an inner surface shape measuring machine comprising:

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