How to calibrate your measuring device

Abstract

To provide a method of calibrating a measuring instrument with which it is possible to calibrate the amount of probe movement with good accuracy.SOLUTION: A first captured image of a probe 30 is captured with a camera 32 while a stage 18 is located at a first linearly moving position. Next, the stage 30 is linearly moved from the first linearly moving position to a second linearly moving position by a first linearly moving mechanism, and then a second captured image of the probe 30 is captured with the camera 32. In this case, the probe 30 is linearly moved by a second linearly moving mechanism so that the position of the probe 30 in the second captured image is the same as the position of the probe 30 in the first captured image. Meanwhile, the amount of linear movement of the probe 30 by the second linearly moving mechanism is calibrated on the basis of correspondence between the amount of linear movement of the stage 18 and the amount of linear movement of the probe 30 when capturing of these images was carried out.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a technique for measuring the inner shape of a small hole formed in a workpiece. [Background technology]

[0002] Conventionally, there has been known a shape measuring machine that measures the inner shape (roundness, etc.) of a cylindrical workpiece by rotating a detector probe and the workpiece relatively around a rotation axis (see, for example, Patent Document 1). In order to measure the inner shape of the workpiece using such a shape measuring machine, it is necessary to align the rotation axis with the central axis of the workpiece.

[0003] Patent Document 1 discloses a technique for measuring the inner shape of the inner peripheral surface of a cylindrical workpiece placed on a rotating table by contacting the probe (contact piece) of a detector with the inner peripheral surface of the workpiece. In the technique described in Patent Document 1, in order to align the rotation axis with the central axis of the workpiece, the detector probe is contacted with the outer peripheral surface of the workpiece in advance, and the runout of the workpiece is observed at low magnification while rotating the rotating table, and the workpiece placement position is adjusted to reduce the runout. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-145344 A Summary of the Invention [Problem to be solved by the invention]

[0005] When measuring the inner shape of a small hole in a workpiece using a shape measuring machine as described above, the relative positioning of the probe and the rotation axis (probe alignment) is important. That is, even if the rotation axis and the central axis of the workpiece are aligned as in the above-mentioned Patent Document 1, if there is a relative positional deviation between the probe and the rotation axis, there is a problem that the probe collides with a part of the workpiece other than the small hole when the probe is inserted into the small hole in the workpiece.

[0006] This problem can be solved by having the operator insert the probe into the small hole in the workpiece while checking with an observation microscope, but this requires the operator to be highly skilled, making automation difficult and raising the risk of the probe colliding with a part of the workpiece other than the small hole due to an operating error.

[0007] The present invention has been made in consideration of the above circumstances, and has an object to provide an inner surface shape measuring machine that can easily perform probe alignment with high accuracy, and an alignment method for an inner surface shape measuring machine. [Means for solving the problem]

[0008] In order to achieve the above object, the following invention is provided.

[0009] An inner surface shape measuring machine according to a first aspect of the present invention is an inner surface shape measuring machine for measuring the inner surface shape of a small hole formed in a workpiece, and comprises a rotation mechanism for rotating the workpiece about a rotation axis, a linear motion tilt stage on which the workpiece is placed, the linear motion tilt stage being rotatable about the rotation axis by the rotation mechanism and capable of linear motion and tilting in a first direction and a second direction perpendicular to the rotation axis, a probe having an elongated shape that can be inserted into the small hole and detecting the inner surface shape of the small hole, an adjustment means for adjusting the attitude of the probe, an acquisition means connected to the linear motion tilt stage via a connecting member and acquiring probe attitude information from at least three circumferential positions on a rotational orbit centered on the rotation axis, and a control means for adjusting the attitude of the probe by the adjustment means based on the probe attitude information acquired by the acquisition means.

[0010] According to a second aspect of the present invention, in the first aspect of the inner surface shape measuring instrument, the adjustment means is a probe linear motion tilt mechanism capable of linearly moving and tilting the probe in a first direction and a second direction.

[0011] According to a third aspect of the present invention, in the first or second aspect of the inner surface shape measuring instrument, the control means adjusts the attitude of the probe by the adjustment means so that there is no relative deviation between the probe and the rotation axis.

[0012] An inner surface shape measuring instrument according to a fourth aspect of the present invention is any one of the first to third aspects, wherein the acquisition means acquires probe attitude information from four circumferential positions shifted by 90 degrees from each other on the rotational orbit.

[0013] An inner surface shape measuring instrument according to a fifth aspect of the present invention is any one of the first to fourth aspects, wherein the acquisition means includes a camera that captures an image of the probe.

[0014] The inner surface shape measuring instrument according to a sixth aspect of the present invention is the fifth aspect, further comprising a surface-emitting illumination means that is configured to be rotatable integrally with the linear motion tilt stage and is capable of emitting surface light towards the probe from a position facing the camera.

[0015] An alignment method for an inner surface shape measuring machine according to a seventh aspect of the present invention is an alignment method for an inner surface shape measuring machine that measures the inner surface shape of a fine hole formed in a workpiece, the inner surface shape measuring machine comprising: a rotation mechanism for rotating the workpiece about a rotation axis; a linear tilt stage on which the workpiece is placed, the linear tilt stage being rotatable about the rotation axis by the rotation mechanism and capable of linear motion and tilting in a first direction and a second direction perpendicular to the rotation axis; a probe having an elongated shape that can be inserted into the fine hole and detecting the inner surface shape of the fine hole; and an acquisition means connected to the linear tilt stage via a connecting member, the alignment method comprising: an acquisition step in which the acquisition means acquires probe attitude information from at least three circumferential positions on a rotational orbit centered on the rotation axis while rotating the acquisition means together with the linear tilt stage about the rotation axis; and an adjustment step in which the attitude of the probe is adjusted based on the probe attitude information acquired in the acquisition step so that there is no relative misalignment between the probe and the rotation axis.

[0016] An alignment method for an inner surface shape measuring machine according to an eighth aspect of the present invention is the seventh aspect, wherein in the pre-acquisition step, an acquisition means acquires probe attitude information from four circumferential positions shifted from each other by 90 degrees on the rotational orbit.

[0017] An alignment method for an inner surface shape measuring machine according to an eighth aspect of the present invention is the same as that of the seventh aspect, wherein the acquisition means is a camera that photographs the probe, and further comprises a focusing step of adjusting the focus of the camera to the rotation axis by moving or tilting the linear motion tilt stage in a linear motion manner. Effect of the Invention

[0018] According to the present invention, the alignment of the probe can be performed easily and with high accuracy. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic diagram showing an overall configuration of an inner surface shape measuring machine according to a first embodiment. [Diagram 2] FIG. 2 is a block diagram showing a configuration of a control device. [Diagram 3] 11 is a flowchart showing an example of a flow of probe alignment. [Figure 4] FIG. 2 is a diagram for explaining camera focusing. [Diagram 5] FIG. 13 is a diagram showing an example of a position where a probe is photographed by a camera. [Figure 6] 1A to 1C are explanatory diagrams showing examples of images captured by a camera at each shooting position. [Figure 7] 13 is a diagram showing a composite image of the first captured image and the third captured image. FIG. [Figure 8] 13 is a diagram showing a composite image of the second captured image and the fourth captured image. FIG. [Figure 9] FIG. 13 is a diagram for explaining work alignment. [Figure 10] FIG. 13 is a diagram for explaining work alignment. [Figure 11] 11A and 11B are diagrams for explaining a method of calibrating the linear movement amount of the probe linear motion tilt mechanism. [Figure 12] 11A and 11B are diagrams for explaining a method for calibrating the tilt movement amount of the probe linear motion tilt mechanism. [Figure 13] 13 is a diagram showing another example of the position at which the probe is photographed by the camera. FIG. [Figure 14] FIG. 13 is a diagram showing yet another example of the position at which the probe is photographed by the camera. [Figure 15] FIG. 11 is a schematic diagram showing the overall configuration of an inner surface shape measuring machine according to a second embodiment. [Figure 16] FIG. 11 is a schematic diagram showing the overall configuration of an inner surface shape measuring machine according to a third embodiment. [Figure 17] FIG. 11 is a schematic diagram showing a configuration of a main part of an inner surface shape measuring machine according to a fourth embodiment. [Figure 18] FIG. 13 is a schematic diagram showing a configuration of a main part of an inner surface shape measuring machine according to a fifth embodiment. [Figure 19] FIG. 13 is a diagram for explaining an application example of the present invention. [Figure 20] FIG. 13 is a diagram for explaining an application example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0021] [First embodiment] <Configuration of inner surface shape measuring machine> Fig. 1 is a schematic diagram showing the overall configuration of an inner surface shape measuring machine 10 of a first 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 through 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.

[0022] As shown in FIG. 1, the inner surface shape measuring machine 10 includes a main body base 12, a high-precision rotation mechanism 14, a linear motion tilt stage 18, a column 20, a carriage 22, an arm 24, a displacement detector 26, a probe linear motion tilt mechanism 28, a probe observation camera 32, a workpiece observation camera 34, and a control device 50.

[0023] The high-precision rotation mechanism 14 is a rotation mechanism for rotating the workpiece W around the rotation axis C, and rotates a linear motion tilt stage 18 (described later) with high precision around the rotation axis C parallel to the Z direction. The high-precision rotation mechanism 14 includes a rotor 16 rotatably mounted on the main body base 12, and the linear motion tilt stage 18 is supported on the upper surface of the rotor 16. The high-precision rotation mechanism 14 includes a motor (not shown) that rotates the rotor 16 with high precision around the rotation axis C, and an encoder (not shown) that detects the rotation angle of the rotor 16. The high-precision rotation mechanism 14 corresponds to the "rotation mechanism".

[0024] The linear motion tilt stage 18 is for placing the workpiece W. The linear motion tilt stage 18 may be a stage that directly supports and fixes the workpiece W, or may be a stage that supports and fixes the workpiece W via a workpiece installation jig (not shown).

[0025] The linear motion tilt stage 18 is supported on the support surface (upper surface) of the rotating body 16, and is configured to be rotatable integrally with the rotating body 16 about the rotation axis C. As a result, the workpiece W supported and fixed to the linear motion tilt stage 18 can be rotated integrally with the linear motion tilt stage 18 about the rotation axis C.

[0026] The linear tilt stage 18 includes a linear mechanism (centering mechanism) and a tilt mechanism (tilting mechanism) (both not shown). The linear mechanism moves the linear tilt stage 18 in the X and Y directions by driving a motor (not shown) to adjust the position of the linear tilt stage 18 in the XY plane (horizontal plane) perpendicular to the rotation axis C. The tilt mechanism rotates the linear tilt stage 18 around the X and Y directions by driving a motor (not shown) to adjust the tilt of the linear tilt stage 18 with respect to the XY plane. Therefore, by adjusting the position and tilt of the linear tilt stage 18 in the horizontal direction (X and Y directions) by the linear mechanism and the tilt mechanism, it is possible to perform eccentricity correction (centering adjustment) and tilt correction (tilting adjustment) of the central axis of the workpiece W with respect to the rotation axis C.

[0027] A column (support) 20 extending parallel to the Z direction is provided on the main body base 12. The column 20 has a lower end fixed to the upper surface of the main body base 12.

[0028] The carriage 22 is supported by the column 20 so as to be movable in the Z direction. The carriage 22 is configured to be movable in the Z direction by being driven by a motor (not shown).

[0029] The arm 24 is supported by the carriage 22 so as to be movable in the X direction. The arm 24 is configured to be movable in the X direction by being driven by a motor (not shown).

[0030] The displacement detector 26 is supported by the arm 24 via a probe linear motion tilt mechanism 28. The displacement detector 26 has an elongated probe 30 that can be inserted into the small hole H of the workpiece W. The probe 30 detects the shape of the inner surface (measurement surface) of the small hole H of the workpiece W when inserted into the small hole H of the workpiece W. A non-contact probe that detects the inner surface shape without coming into contact with the inner surface of the small hole H of the workpiece W is preferably used as the probe 30.

[0031] The non-contact probe is not particularly limited as long as it can detect the inner shape of the fine hole H in the workpiece W without contacting the inner surface. For example, a probe that applies various techniques such as a laser interferometer, a white light interferometer, SD-OCT (Spectral Domain-Optical Coherence Tomography), or SS-OCT (Swept Source-Optical Coherence Tomography) can be used.

[0032] The probe 30 is not limited to a non-contact probe, and may be a contact probe. The contact probe has a contactor that can come into contact with the inner surface of the fine hole H in the workpiece W, and detects the shape of the inner surface by detecting the displacement of the contactor when it is brought into contact with the inner surface of the fine hole H in the workpiece W. As the contact probe, for example, a probe using various methods such as an LVDT (Linear Variable Differential Transformer), an interferometer, an optical triangulation method, and a thin film distortion measurement method may be used. In addition, a method may be applied in which the contactor of the contact probe is vibrated at a resonance frequency and the resonance point changes due to contact.

[0033] In general, non-contact probes are more suitable for making the diameter smaller than contact probes, and are therefore suitable for measuring the inner shape of a very small diameter fine hole H as in this embodiment.

[0034] The probe linear motion tilt mechanism 28 is provided between the arm 24 and the displacement detector 26. The probe linear motion tilt mechanism 28 includes a linear motion mechanism and a tilt mechanism (both not shown). The linear motion mechanism moves the displacement detector 26 in the X and Y directions by driving a motor (not shown) to adjust the position of the probe 30 in the XY plane (horizontal plane) perpendicular to the rotation axis C. The tilt mechanism rotates the displacement detector 26 around the X and Y directions by driving a motor (not shown) to adjust the tilt of the probe 30 with respect to the XY plane. Therefore, by adjusting the position and tilt of the probe 30 in the horizontal direction (X and Y directions) by the probe linear motion tilt mechanism 28 (linear motion mechanism and tilt mechanism), it is possible to perform relative positioning (probe alignment) between the probe 30 and the rotation axis C. The probe linear motion tilt mechanism 28 is an example of an "adjustment means". Probe alignment, which is a feature of the present invention, will be described later.

[0035] The probe observation camera 32 is an area sensor camera (two-dimensional sensor camera) such as a CCD (Charge Coupled Device) camera. The probe observation camera 32 is connected (supported) to the linear motion tilt stage 18 via a camera bracket 36. The probe observation camera 32 is arranged so that its shooting direction is perpendicular to the rotation axis C and faces the rotation axis C side (rotation center side). In addition, the focus of the probe observation camera 32 is adjusted to match the rotation axis C by focusing, which will be described later. As a result, the probe observation camera 32 can rotate around the rotation axis C together with the linear motion tilt stage 18, and the probe 30 can be photographed by the probe observation camera 32 at any shooting position (circumferential position) on the rotation path K centered on the rotation axis C (see FIG. 5). Note that power can be supplied to the probe observation camera 32 by a known method such as a slip ring or wireless power supply. The probe observation camera 32 is an example of an "acquisition means", and the image captured by the probe observation camera 32 is an example of "probe attitude information". Moreover, the camera bracket 36 is an example of a "connecting member."

[0036] The workpiece observation camera 34 is an area sensor camera (two-dimensional sensor camera) such as a CCD camera, similar to the above-mentioned probe observation camera 32. The upper end of the workpiece observation camera 34 is supported by the arm 24, and is disposed so that its shooting direction faces downward in the vertical direction (downward in the Z direction) parallel to the rotation axis C. This enables the workpiece observation camera 34 to shoot the workpiece W supported and fixed to the linearly moving tilt stage 18 from a fixed position (fixed position).

[0037] <Control device> The control device 50 controls the operation of each part of the inner surface shape measuring machine 10 (including the operation of measuring the inner surface shape of the workpiece W and the probe alignment operation described below). The control device 50 is realized by a general-purpose computer such as a personal computer or a microcomputer. The control device 50 is equipped with a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, etc. In the control device 50, various programs such as a control program stored in the ROM are expanded in the RAM, and the programs expanded in the RAM are executed by the CPU, thereby realizing the functions of each part in the inner surface shape measuring machine 10, and various arithmetic processing or control processing is executed via the input / output interface. The control device 50 is an example of a "control means".

[0038] Fig. 2 is a block diagram showing the configuration of the control device 50. Note that Fig. 2 shows only the configuration related to the operation of probe alignment executed by the inner surface shape measuring machine 10. Note that the control device 50 also includes configuration related to the operation of measuring the inner surface shape of the workpiece W, but since this is not a main part of the present invention, a description thereof will be omitted.

[0039] 2, the control device 50 includes a probe alignment control unit 52. The probe alignment control unit 52 is a functional unit that controls an operation for performing relative position alignment (probe alignment) between the probe 30 and the rotation axis C.

[0040] Here, the configuration of the probe alignment control unit 52 will be explained in detail. The probe alignment control unit 52 includes an imaging control unit 54, a relative deviation detection unit 56, and a probe attitude control unit 58.

[0041] The photographing control unit 54 controls the high-precision rotation mechanism 14 to rotate the probe observation camera 32 around the rotation axis C together with the rotor 16 and the linear tilt stage 18, thereby changing the photographing position (circumferential position) of the probe observation camera 32 relative to the probe 30 in the circumferential direction around the rotation axis C. This allows the probe observation camera 32 to photograph the probe 30 from at least three photographing positions on the rotation orbit K of the probe observation camera 32 around the rotation axis C. As will be described later, in this embodiment, the probe 30 is preferably photographed from four photographing positions shifted by 90 degrees from each other on the rotation orbit K of the probe observation camera 32 (see FIG. 5). In addition, before the above photographing operation is performed, the photographing control unit 54 controls the linear tilt stage 18 to adjust the position and inclination of the linear tilt stage 18 in the horizontal direction (X direction and Y direction) to adjust the focus of the probe observation camera 32 to the rotation axis C.

[0042] Furthermore, the imaging control unit 54 controls the probe observation camera 32 that has moved to each imaging position to image the probe 30. The imaging control unit 54 causes the probe observation camera 32 to transmit the images captured by the probe observation camera 32 to the relative deviation detection unit 56.

[0043] The relative deviation detection unit 56 detects the relative deviation between the rotation axis C and the probe 30 based on the captured images acquired by the probe observation camera 32 at each capturing position. A specific detection method will be described in the probe alignment section below.

[0044] The probe posture control unit 58 controls the probe linear motion tilt mechanism 28 based on the relative deviation detected by the relative deviation detection unit 56. Specifically, the probe posture control unit 58 controls the probe linear motion tilt mechanism 28 to adjust the position and tilt of the probe 30 so that the relative deviation detected by the relative deviation detection unit 56 is eliminated, thereby aligning the probe 30 with the rotation axis C relatively.

[0045] <Probe alignment> Next, probe alignment, which is a feature of the present invention, will be described.

[0046] When using the inner surface shape measuring machine 10 to measure the inner surface shape (roundness, etc.) of a small hole H in a workpiece W, first, the probe 30 is moved in the Z direction together with the displacement detector 26 by the carriage 22, and the probe 30 is inserted into the small hole H in the workpiece W. Then, with the probe 30 inserted into the small hole H in the workpiece W, the workpiece W is rotated around the rotation axis C while the probe 30 detects the inner surface shape of the small hole H. In this manner, the inner surface shape of the small hole H in the workpiece W is measured.

[0047] Here, in order to insert the probe 30 into the fine hole H before the measurement is started, it is necessary to adjust the attitude (position and inclination) of the probe 30 so that the probe 30 is positioned coaxially with the rotation axis C. If there is a relative misalignment between the probe 30 and the rotation axis C, when an attempt is made to insert the probe 30 into the fine hole H, the probe 30 will collide with a portion of the workpiece W other than the fine hole H, making it difficult to measure the inner shape of the fine hole H.

[0048] Therefore, in this embodiment, before measurement of the inner shape of the fine hole H in the workpiece W begins, relative alignment (probe alignment) between the probe 30 and the rotation axis C is performed so that there is no relative misalignment between the probe 30 and the rotation axis C.

[0049] FIG. 3 is a flowchart showing an example of a flow of probe alignment.

[0050] As shown in FIG. 3, when the probe alignment is started, first, the imaging control unit 54 performs focusing so that the focal point of the probe observation camera 32 is aligned with the rotation axis C (step S10, an example of a "focusing step"). Here, in this embodiment, since the probe observation camera 32 is supported on the linear tilt stage 18 via the camera bracket 36, as shown in FIG. 4, the imaging control unit 54 controls the linear tilt stage 18 to adjust the position and tilt of the linear tilt stage 18 in the horizontal direction (X direction and Y direction), thereby making it possible to focus the probe observation camera 32 as described above. Note that the probe observation camera 32 may have an automatic focusing function (autofocus function) that measures the distance to the subject (probe 30) and performs focusing.

[0051] Next, the imaging control unit 54 controls the high-precision rotation mechanism 14 to rotate the probe observation camera 32 together with the linear tilt stage 18 around the rotation axis C (step S12). Then, when the probe observation camera 32 moves to a predetermined imaging position on the rotation orbit K of the probe observation camera 32 centered on the rotation axis C, the probe 30 is imaged by the probe observation camera 32 at the imaging position (step S14, an example of an "acquisition step").

[0052] Next, it is determined whether or not imaging at all the imaging positions has been completed (step S16). If it is determined that imaging at all the imaging positions has not been completed (No in step S16), the rotational movement of the probe observation camera 32 (step S12) and the imaging of the probe 30 by the probe observation camera 32 (step S14) are repeated until it is determined that imaging at all the imaging positions has been completed. Whether or not the probe observation camera 32 has moved to each imaging position can be determined based on the output of an encoder provided in the high-precision rotation mechanism 14. Any other configuration can be applied, not limited to an encoder, as long as it can determine whether or not the probe observation camera 32 has moved to each imaging position.

[0053] Fig. 5 is a diagram showing an example of an imaging position of the probe 30 by the probe observation camera 32. As shown in Fig. 5, in the probe alignment in this embodiment, the probe observation camera 32 is rotationally moved about the rotation axis C by the rotational movement of the linear tilt stage 18, and the probe 30 is imaged by the probe observation camera 32 at a predetermined imaging position (circumferential position) on the rotational orbit K of the probe observation camera 32 about the rotation axis C. Specifically, the probe 30 is imaged by the probe observation camera 32 at four imaging positions P1 to P4 that are shifted from each other by 90 degrees on the rotational orbit K of the probe observation camera 32 about the rotation axis C.

[0054] Regarding the planar (XY plane) positional relationship of the four shooting positions P1 to P4, the first shooting position P1 and the third shooting position P3 are opposed to each other in the first direction (Y direction) of two mutually orthogonal directions, and the second shooting position P2 and the fourth shooting position P4 are opposed to each other in the second direction (X direction).

[0055] In this embodiment, the direction in which the probe 30 is photographed by the probe observation camera 32 from the four photographing positions P1 to P4 is the X direction or the Y direction, which is the same as the control direction (movement axis direction) in which the probe 30 is moved linearly or tilted by the probe linear motion tilt mechanism 28.

[0056] In this embodiment, as one preferred aspect, the first direction (Y direction) in which the first photographing position P1 and the third photographing position P3 face each other and the second direction (X direction) in which the second photographing position P2 and the fourth photographing position P4 face each other are consistent with the control direction of the probe linear motion tilt mechanism 28, but this is not necessarily limited to this aspect. For example, the direction may be different from the control direction of the probe linear motion tilt mechanism 28, and the first direction and the second direction may not be orthogonal to each other. However, this embodiment is preferable because the relative deviation between the probe 30 and the rotation axis C can be simply and easily detected independently in each direction.

[0057] Returning to Figure 3, when it is determined that the probe 30 has been photographed by the probe observation camera 32 at all shooting positions (Yes in step S16), the relative deviation detection unit 56 detects the relative deviation between the probe 30 and the rotation axis C based on the images captured by the probe observation camera 32 at each shooting position (step S18).

[0058] Here, detection of the relative deviation between the probe 30 and the rotation axis C will be described in detail.

[0059] Fig. 6 is a diagram showing an example of images captured by the probe observation camera 32 at each of the photographing positions P1 to P4. In Fig. 6, a first photographed image 100A is an image captured at the first photographing position P1, and similarly, a second photographed image 100B is an image captured at the second photographing position P2, a third photographed image 100C is an image captured at the third photographing position P3, and a fourth photographed image 100D is an image captured at the fourth photographing position P4.

[0060] When there is a relative misalignment between the probe 30 and the rotation axis C, for example as shown in FIG. 6, in the captured images 100A to 100D captured by the probe observation camera 32 at each of the capturing positions P1 to P4, the attitude (position and inclination) of the probe 30 differs depending on the difference in the capturing position (i.e., the capturing direction of the probe 30 by the probe observation camera 32).

[0061] For example, in a first photographed image 100A photographed from one photographing position (first photographing position P1) of two photographing positions (first photographing position P1 and third photographing position P3) facing each other in the first direction (Y direction), the probe 30A is inclined to one side in the second direction (X direction), whereas in a third photographed image 100C photographed from the other photographing position (third photographing position P3), the probe 30C is inclined to the other side in the second direction (X direction). Also, the positions in the second direction (X direction) are shifted toward opposite sides.

[0062] The same is true for the second captured image 100B and the fourth captured image 100D at two shooting positions (second captured position P2 and fourth captured position P4) facing each other in the second direction (X direction), where the positions and inclinations of the probes 30B and 30D are shifted in opposite directions.

[0063] FIG. 7 is a diagram showing a first composite image 102A obtained by combining a first captured image 100A and a third captured image 100C captured from two opposing capturing positions (first capturing position P1 and third capturing position P3) in the first direction (Y direction).

[0064] As shown in FIG. 7, in the first composite image 102A obtained by combining the first photographed image 100A and the third photographed image 100C, a first midline ML1 between the central axis (first probe central axis) L1 of the probe 30A in the first photographed image 100A and the central axis (third probe central axis) L3 of the probe 30C in the third photographed image 100C indicates the position of the rotation axis C in the XZ plane (i.e., the position of the rotation axis C when the probe 30 is viewed from the first direction (Y direction)). The first midline ML1 refers to a straight line passing through the center of the first probe central axis L1 and the third probe central axis L3 in the horizontal direction (X direction) in the first composite image 102A in the vertical direction (Z direction). In other words, the straight line that bisects the space between the first probe central axis L1 and the third probe central axis L3 in the left and right (X direction) in the first composite image 102A is called the first midline ML1.

[0065] The first midline ML1 in the first composite image 102A indicates the position of the rotation axis C. That is, the first midline ML1 indicates a line that is a movement target of the probe 30 in the first composite image 102A (in the XZ plane), and by adjusting the attitude (position and inclination) of the probe 30 so that the probe 30 coincides with the first midline ML1, it is possible to eliminate the relative deviation between the rotation axis C and the probe 30 in the XZ plane.

[0066] FIG. 8 is a diagram showing a composite image 102B obtained by combining a second captured image 100B and a fourth captured image 100D captured from two capturing positions (second capturing position P2 and fourth capturing position P4) facing each other in the second direction (X direction).

[0067] As shown in FIG. 7, in the second composite image 102B obtained by combining the second photographed image 100B and the fourth photographed image 100D, a second midline ML2 between the central axis (second probe central axis) L2 of the probe 30B in the second photographed image 100B and the central axis (fourth probe central axis) L4 of the probe 30D in the fourth photographed image 100D indicates the position of the rotation axis C in the YZ plane (i.e., the position of the rotation axis C when the probe 30 is viewed from the second direction (X direction)). The second midline ML2 refers to a straight line passing through the center of the second probe central axis L2 and the fourth probe central axis L4 in the horizontal direction (X direction) in the second composite image 102B in the vertical direction (Z direction). In other words, the straight line that bisects the space between the second probe central axis L2 and the fourth probe central axis L4 in the left and right (X direction) in the second composite image 102B is called the second midline ML2.

[0068] The second midline ML2 in the second composite image 102B indicates the position of the rotation axis C. That is, the second midline ML2 indicates a line that is a movement target of the probe 30 in the second composite image 102B (in the YZ plane), and by adjusting the attitude (position and inclination) of the probe 30 so that the probe 30 coincides with the second midline ML2, it is possible to eliminate the relative deviation between the rotation axis C and the probe 30 in the YZ plane.

[0069] Therefore, by calculating the two midlines ML1 and ML2 mentioned above based on the images captured by the probe observation camera 32 at four shooting positions P1 to P4 that are shifted by 90 degrees from each other on the rotational orbit K of the probe observation camera 32 centered on the rotational axis C, the rotational axis C (center of rotation) which is the movement target of the probe 30 can be detected, and the relative deviation between the rotational axis C and the probe 30 can be adjusted independently in each direction (X direction and Y direction).

[0070] Therefore, in the probe alignment of this embodiment, when one of the two probes 30 in the first composite image 102A shown in Fig. 7 is set as the reference probe (in this example, the probe 30A in the first captured image 100A), the relative deviation detection unit 56 detects, as the tilt movement amount θ, the tilt angle (rotation angle about the Y direction) for making the probe central axis of the reference probe parallel to the first midline ML1, and detects, as the linear movement amount Dx, the movement distance in the X direction required for making the probe central axis of the reference probe coincide with the first midline ML1 when the probe central axis of the reference probe is tilted by the tilt movement amount θ to be parallel to the first midline ML1. The linear movement amount Dx corresponds to the distance in the direction along the movement axis in the X direction of the probe linear motion tilt mechanism 28 (see Fig. 7).

[0071] 8, when one of the two probes 30 is set as the reference probe (probe 30B in the second captured image 100B in this example), the relative deviation detection unit 56 detects, as the tilt movement amount φ, the tilt angle (rotation angle about the X direction) for making the probe central axis of the reference probe parallel to the second midline ML2, and detects, as the linear movement amount Dy, the movement distance in the Y direction required for making the probe central axis of the reference probe coincide with the second midline ML2 when the probe central axis of the reference probe is tilted by the tilt movement amount φ to be parallel to the second midline ML2. The linear movement amount Dy corresponds to the distance in the direction along the movement axis in the Y direction of the probe linear motion tilt mechanism 28 (see FIG. 8).

[0072] The relative deviation detection unit 56 can calculate the probe central axes C1 to C4, midlines ML1 and ML2, linear movement amounts Dx and Dy, and tilt movement amounts θ and φ from each of the composite images 102A and 102B by known image processing such as edge extraction.

[0073] In this way, when the relative deviation detection unit 56 detects the relative deviation between the probe 30 and the rotation axis C in each direction independently based on the captured images captured by the probe observation camera 32 at each capturing position (step S18), the probe attitude control unit 58 controls the probe linear motion tilt mechanism 28 based on the results detected by the relative deviation detection unit 56. Specifically, the probe attitude control unit 58 controls the probe linear motion tilt mechanism 28 to move the probe 30 by a linear motion movement amount Dx in the X direction and by a linear motion movement amount Dy in the Y direction, and tilt the probe 30 by a tilt movement amount φ around the X direction and by a tilt movement amount θ around the Y direction (step S20, an example of an "adjustment step"). The direction (orientation) in which the probe linear motion tilt mechanism 28 is moved or tilted is determined depending on which probe is set as the reference probe in the composite images 102A and 102B shown in FIG. 7 or FIG. 8.

[0074] As described above, when the probe attitude control unit 58 controls the probe linear motion tilt mechanism 28 to change the attitude of the probe 30 based on the result detected by the relative deviation detection unit 56, the relative deviation between the probe 30 and the rotation axis C in the three-dimensional space disappears. With this, this flowchart is completed.

[0075] <Work alignment> In the above-mentioned probe alignment, the focus of the probe observation camera 32 is performed by adjusting the position and inclination of the linear motion tilt stage 18 in the horizontal direction (X direction and Y direction). Therefore, if the central axis of the workpiece W is aligned with respect to the rotation axis C (workpiece alignment) before the probe alignment is performed, a relative deviation may occur between the rotation axis C and the center of the workpiece W due to the movement of the linear motion tilt stage 18 accompanying the focusing of the probe observation camera 32. Therefore, in this embodiment, it is preferable to perform the workpiece alignment described later after the probe alignment is performed.

[0076] In the workpiece alignment in this embodiment, the workpiece W supported and fixed to the linear inclined stage 18 is rotated about the rotation axis C by the rotational movement of the rotor 16, while the workpiece W is photographed by the workpiece observation camera 34. At this time, the workpiece observation camera 34 photographs the workpiece W when it moves to two positions shifted from each other by 180 degrees in the circumferential direction (the rotation direction of the workpiece W) about the rotation axis C (i.e., two positions facing each other about the rotation axis C).

[0077] 9 and 10 are diagrams for explaining workpiece alignment. FIG. 9 is a diagram showing an example of captured images captured by the workpiece observation camera 34 at two positions facing each other about the rotation axis C. In FIG. 9, a first captured image 104A is a captured image captured at a first rotation position (e.g., 0 degree position), and a second captured image 104B is a captured image captured at a second rotation position (e.g., 180 degree position). FIG. 10 is a diagram showing a composite image 106 obtained by combining the first captured image 104A and the second captured image 104B captured at two rotation positions facing each other about the rotation axis C.

[0078] When the center of the workpiece W does not coincide with the rotation axis C (when there is eccentricity), the position of the workpiece W with respect to the rotation axis C changes in the circumferential direction (the rotation direction of the workpiece W around the rotation axis C). At this time, as shown in FIG. 9, for example, in a first captured image 104A captured at a first rotation position, the workpiece W1 is disposed at a position eccentric to one side in the X direction and the Y direction with respect to the rotation axis C, whereas in a second captured image 104B captured at a second rotation position which is a position shifted 180 degrees from the first rotation position, the workpiece W2 is disposed at a position eccentric to the other side in the X direction and the Y direction (opposite to the one side) from the workpiece W1 in the first captured image 104A. That is, the workpiece W1 in the first captured image 104A and the workpiece W2 in the second captured image 104B are in a positional relationship that is point-symmetric with respect to the rotation axis C.

[0079] As shown in Fig. 10, in a composite image 106 obtained by combining the first captured image 104A and the second captured image 104B, the midpoint of a line segment connecting the center O1 of the workpiece W1 in the first captured image 104A and the center O2 of the workpiece W2 in the second captured image 104B indicates the position of the rotation axis C in the XY plane. That is, the midpoint (rotation axis C) indicates a position to which the center of the workpiece W is moved in the composite image 106 (in the XY plane), and it is possible to eliminate the eccentricity between the rotation axis C and the center of the workpiece W in the XY plane by moving the linear tilt stage 18 in the horizontal direction (X direction and Y direction) so that the center (O1 or O2) of the workpiece W coincides with the midpoint. Note that the movement distances (linear movement amounts) Ex and Ey in the X and Y directions required to coincide the center of the workpiece W with the rotation axis C can be obtained as the distances in each direction between the center of the workpiece W and the rotation axis C, as shown in Fig. 10.

[0080] Thus, in the workpiece alignment of this embodiment, the position of the rotation axis C (center of rotation), which is the movement target of the workpiece W, can be detected from the images (workpiece images) captured by the workpiece observing camera 34 at each rotation position. In other words, the eccentricity of the center of the workpiece W with respect to the rotation axis C can be detected based on the two images captured by the workpiece observing camera 34.

[0081] Then, based on the eccentricity deviation detected in this manner, the linear tilt stage 18 is moved in the horizontal direction (X direction and Y direction) to make the center of the workpiece W coincide with the rotation axis C. Note that the control of each part related to workpiece alignment is performed by a workpiece alignment control part (not shown) of the control device 50. Also, the workpiece observation camera 34 may be one that captures multiple still images at each rotation position, or one that captures a video of the workpiece W during its rotational movement.

[0082] In the workpiece alignment of this embodiment, images taken at two opposing rotational positions in the circumferential direction about the rotational axis C are used, but the present invention is not limited to this and may use images taken at at least three rotational positions in the circumferential direction about the rotational axis C as long as it is possible to detect the position of the rotational axis C (center of rotation) that is the movement target of the workpiece W. In this case, the range in which the workpiece observation camera 34 rotates can be limited to a partial range, making it possible to perform workpiece alignment more efficiently in a shorter time.

[0083] By performing the probe alignment and workpiece alignment as described above, it is possible to eliminate the relative misalignment between the rotation axis C, the probe 30, and the center of the workpiece W. As a result, when measuring the inner shape of the fine hole H in the workpiece W, the probe 30 does not collide with parts of the workpiece W other than the fine hole H, and it is possible to stably and reliably measure the inner shape of the fine hole H.

[0084] <Calibration of the probe linear tilt mechanism> Next, calibration of the linear movement amount and the tilt movement amount in the probe linear motion tilt mechanism 28 will be described.

[0085] In the inner surface shape measuring machine 10 of this embodiment, if the relative position between the center of the workpiece W and the rotation axis C or the rotation position of the workpiece W changes for each measurement operation, this affects the measurement accuracy. Therefore, the linear tilt stage 18 and the high-precision rotation mechanism 14 are required to have high accuracy.

[0086] Furthermore, in order to perform the above-mentioned probe alignment with high accuracy, it is desirable to use a highly accurate probe linear motion tilt mechanism 28. However, if a high-precision scale or high-resolution encoder is mounted on the probe linear motion tilt mechanism 28, there is a possibility that costs will increase due to the addition of wiring to the moving parts in the probe linear motion tilt mechanism 28, and that the wiring may adversely affect the accuracy of the driving part. Also, a heating element will be added near the measurement part (scale) in the probe linear motion tilt mechanism 28, which may cause a deterioration in accuracy due to temperature changes.

[0087] Therefore, in this embodiment, in order to perform probe alignment with high accuracy without being affected by the accuracy of the probe linear motion tilt mechanism 28, it is preferable to calibrate the probe linear motion tilt mechanism 28 as follows.

[0088] Fig. 11 is a diagram for explaining a method for calibrating the linear movement amount of the probe linear motion tilt mechanism 28. Fig. 11 is a side view showing the main configuration of the inner surface shape measuring instrument 10 when viewed from the X direction. In Fig. 11, 204A is a diagram showing a state when the linear motion tilt stage 18 is in an initial position, and 204B is a diagram showing a state when the linear motion tilt stage 18 is in a shift position having been moved a specified amount from the initial position in the Y direction. Symbol S indicates the field of view of the probe observation camera 32 (same as in Fig. 12).

[0089] When calibrating the linear motion movement amount of the probe linear motion tilt mechanism 28, first, the high-precision rotation mechanism 14 is operated to rotate the linear motion tilt stage 18 around the rotation axis C, and the movement axis direction of the linear motion tilt stage 18 is aligned with the movement axis directions (X direction and Y direction) of the probe linear motion tilt mechanism 28.

[0090] Next, as shown in 204A of FIG. 11, with the linear motion tilt stage 18 in the initial position, the probe 30 is photographed by the probe observation camera 32.

[0091] 11, the linear motion tilt stage 18 is moved to a shift position away from the initial position by a specified amount in the Y direction. At this time, since the probe observation camera 32 is supported by the linear motion tilt stage 18 via the camera bracket 36, the probe observation camera 32 also moves by the specified amount in the Y direction together with the linear motion tilt stage 18. As a result, the field of view S of the probe observation camera 32 moves from the position indicated by the two-dot chain line to the position indicated by the solid line.

[0092] Next, with the linear motion tilt stage 18 in the shift position, the probe 30 is photographed by the probe observation camera 32. At this time, the probe 30 is moved in the Y direction by the probe linear motion tilt mechanism 28 so that the position of the probe 30 in the photographed image (shifted image) of the probe 30 photographed by the probe observation camera 32 is the same as the position of the probe 30 in the photographed image (reference image) photographed by the probe observation camera 32 when the linear motion tilt stage 18 is in the initial position.

[0093] When the position of the probe 30 is the same in the reference image and the shifted image, the probe linear motion tilt mechanism 28 has moved by the linear motion movement amount by which the linear motion tilt stage 18 has moved from the initial position to the shifted position. The same applies to the linear motion movement amount in the X direction.

[0094] Therefore, by determining the correspondence between the linear movement amount of the linear motion tilt stage 18 and the linear movement amount of the probe linear motion tilt mechanism 28 for each direction (X direction and Y direction), it becomes possible to calibrate the linear movement amount of the probe linear motion tilt mechanism 28 based on the correspondence. This makes it possible to ensure the same accuracy as the linear motion tilt stage 18 in the probe linear motion tilt mechanism 28 as well.

[0095] Fig. 12 is a diagram for explaining a method for calibrating the tilt movement amount of the probe linear motion tilt mechanism 28. Fig. 12 is a side view showing a main configuration of the inner surface shape measuring instrument 10 when viewed from the X direction. In Fig. 12, 206A is a diagram showing a state when the linear motion tilt stage 18 is in the initial position, 206B is a diagram showing a state when the linear motion tilt stage 18 is tilted a specified amount around the X direction from the initial position, and 206C is a diagram showing a state when the probe 30 is further tilted around the X direction by the probe linear motion tilt mechanism 28.

[0096] When calibrating the tilt movement amount of the probe linear motion tilt mechanism 28, the rotation center of the linear motion tilt stage 18 and the rotation center of the probe linear motion tilt mechanism 28 are aligned as shown in 206A in Fig. 12. Note that in Fig. 12, the position indicated by the symbol M is the rotation center of the linear motion tilt stage 18 and the probe linear motion tilt mechanism 28.

[0097] Next, as shown at 206A in FIG. 12, with the linear motion tilt stage 18 in the initial position, the probe 30 is photographed by the probe observation camera 32.

[0098] After that, as shown in 206B of Fig. 12, the linear motion tilt stage 18 is moved to a shift position tilted a specified amount around the X direction. At this time, since the probe observation camera 32 is supported by the linear motion tilt stage 18 via the camera bracket 36, the probe observation camera 32 is also tilted a specified amount around the X direction together with the linear motion tilt stage 18. As a result, the field of view S of the probe observation camera 32 moves from the position indicated by the two-dot chain line to the position indicated by the solid line.

[0099] Next, with the linear motion tilt stage 18 in the shift position, the probe 30 is photographed by the probe observation camera 32. At this time, the probe 30 is tilted around the X direction by the probe linear motion tilt mechanism 28 so that the position of the probe 30 in the photographed image (shifted image) of the probe 30 photographed by the probe observation camera 32 is the same as the position of the probe 30 in the photographed image (reference image) photographed by the probe observation camera 32 when the linear motion tilt stage 18 is in the initial position.

[0100] When the position of the probe 30 is the same in the reference image and the shifted image, the probe linear motion tilt mechanism 28 is tilted by the amount of tilt movement of the linear motion tilt stage 18 from the initial position to the shifted position. The same applies to the amount of tilt movement around the Y direction.

[0101] Therefore, by determining the correspondence between the tilt movement amount of the linear motion tilt stage 18 and the tilt movement amount of the probe linear motion tilt mechanism 28 for each direction (X direction and Y direction), it becomes possible to calibrate the tilt movement amount of the probe linear motion tilt mechanism 28 based on the correspondence. This makes it possible to ensure the same accuracy as the linear motion tilt stage 18 in the probe linear motion tilt mechanism 28 as well.

[0102] As described above, according to this embodiment, it is possible to ensure the same accuracy as the linear tilt stage 18 without being affected by the accuracy of the probe linear tilt mechanism 28, which eliminates the need for high-accuracy position detectors such as scales and encoders, thereby enabling reduction in cost and space of the probe linear tilt mechanism 28. Also, it becomes possible to prevent a decrease in alignment accuracy caused by heat generated by the probe linear tilt mechanism 28.

[0103] <Effects> According to the probe alignment in this embodiment, the relative deviation between the probe 30 and the rotation axis C can be detected independently in each direction (X direction and Y direction) based on four captured images 100A to 100D of the probe 30 captured by the probe observation camera 32 at four capture positions P1 to P4 shifted by 90 degrees from each other on the rotation orbit K of the probe observation camera 32 centered on the rotation axis C. This makes it possible to control the attitude (position and inclination) of the probe 30 independently in each direction by the probe linear motion tilt mechanism 28, and it becomes possible to eliminate the relative deviation between the probe 30 and the rotation axis C with higher accuracy. Therefore, even if the fine hole H of the work W is a very small diameter hole with an inner diameter of about 140 μm and the probe 30 is a very small diameter probe with an outer diameter of about 80 μm, for example, it becomes possible to perform the probe alignment with high accuracy and easily. Therefore, it becomes possible to stably and reliably measure the inner shape of the fine hole H without the probe 30 colliding with the part other than the fine hole H of the work W.

[0104] In particular, in this embodiment, since the probe observation camera 32 is connected to the linear tilt stage 18 via the camera bracket 36, in focusing the above-mentioned probe observation camera 32, it is possible to use the linear tilt stage 18 to make the focus of the probe observation camera 32 coincide with the rotation axis C. Therefore, since there is no need to separately provide a focus adjustment mechanism for focusing the probe observation camera 32, it is possible to achieve both low cost and space saving, and to improve rotation accuracy by reducing the load.

[0105] Furthermore, according to the probe alignment of this embodiment, the position of the rotation axis C (center of rotation) which is the movement target of the probe 30 is detected by relatively comparing images taken from a plurality of different directions using the probe observation camera 32 which rotates integrally with the linear tilt stage 18. Therefore, even if the probe observation camera 32 is attached with a positional deviation in a predetermined direction relative to the camera bracket 36, causing a deviation in the relative positional relationship between the probe observation camera 32 and the rotation axis C, for example, it is possible to perform accurate relative alignment between the probe 30 and the rotation axis C, and precision in attaching the probe observation camera 32 is not required.

[0106] Furthermore, in the probe alignment of this embodiment, the relative position between the probe observation camera 32 and the probe 30 is changed in the circumferential direction around the rotation axis C to perform imaging. Therefore, even if the position of the rotation axis C is unclear or the rotation axis C is tilted, it is possible to accurately align the relative position between the probe 30 and the rotation axis C from the images captured by the probe observation camera 32 at each imaging position P1 to P4.

[0107] Furthermore, according to the method for calibrating the probe linear tilt mechanism 28 in this embodiment, the (linear movement amount and tilt movement amount) of the probe linear tilt mechanism 28 can be calibrated based on the movement amount (linear movement amount and tilt movement amount) of the linear tilt stage 18, so that it is possible to ensure accuracy equivalent to that of the linear tilt stage 18 without being influenced by the accuracy of the probe linear tilt mechanism 28. Therefore, the probe linear tilt mechanism 28 does not require a high-precision position detector such as a scale or encoder, and it is possible to reduce the cost and space of the probe linear tilt mechanism 28. Also, it is possible to prevent a decrease in alignment accuracy caused by heat generated by the probe linear tilt mechanism 28.

[0108] <Modification> In the probe alignment of this embodiment, the relative misalignment between the probe 30 and the rotation axis C is detected independently in each direction based on four captured images 100A to 100D of the probe 30 captured by the probe observation camera 32 at four shooting positions P1 to P4 shifted by 90 degrees from each other on the rotation orbit K of the probe observation camera 32 centered on the rotation axis C. However, this is not limited to this, and the probe 30 may be captured by the probe observation camera 32 from at least three shooting positions on the rotation orbit K of the probe observation camera 32 centered on the rotation axis C, as shown in FIG. 13, for example.

[0109] That is, if the relative deviation between the probe 30 and the rotation axis C can be detected independently in each direction, it is sufficient that the probe 30 is imaged by the probe observation camera 32 from at least three directions centered on the rotation axis C. In this case, the relative deviation between the probe 30 and the rotation axis C can be detected independently in each direction by relatively comparing the images taken by the probe observation camera 32 at each shooting position in relation to the position information (rotation angle, rotation radius, etc.) regarding each shooting position. Then, based on the detected relative deviation, it becomes possible to control the attitude of the probe 30 independently in each direction by the probe linear motion tilt mechanism 28. This makes it possible to eliminate the relative deviation between the probe 30 and the rotation axis C.

[0110] 14, the probe observation camera 32 may continuously capture images of the probe 30 at a fixed interval while rotating the probe observation camera 32 by the rotational movement of the linear tilt stage 18. In this case, a large number of captured images can be used, so that the probe alignment can be performed with high accuracy. Also, by continuously capturing images of the probe 30 while the probe observation camera 32 is rotating, it is possible to limit the range in which the probe observation camera 32 rotates to a certain range, so that the probe alignment can be performed efficiently in a shorter time.

[0111] [Second embodiment] Fig. 15 is a schematic diagram showing the configuration of an inner surface shape measuring machine 10B of the second embodiment. As shown in Fig. 13, the inner surface shape measuring machine 10B of the second embodiment further includes an illumination device 38 at a position facing the probe observation camera 32 across the rotation axis C, in addition to the configuration of the inner surface shape measuring machine 10 of the first embodiment.

[0112] The lighting device 38 is attached to the linear motion tilt stage 18 via a lighting device bracket 40, and can rotate integrally with the linear motion tilt stage 18 around the rotation axis C. The lighting device 38 is a surface-emitting lighting device capable of emitting light from a surface. The lighting device 38 is an example of a "surface-emitting lighting means."

[0113] According to the second embodiment, when the probe observation camera 32 photographs the probe 30 while rotating the probe observation camera 32 around the rotation axis C together with the linear tilt stage 18, the illumination device 38 rotates around the rotation axis C together with the linear tilt stage 18 at a position facing the probe observation camera 32. Therefore, the probe observation camera 32 photographs the probe 30 while maintaining the relative positional relationship between the probe observation camera 32 and the illumination device 38, so that the probe 30 can be photographed under the same illumination conditions regardless of the photographing position of the probe observation camera 32. This makes it possible to prevent a decrease in detection accuracy due to differences in illumination conditions, and to perform probe alignment with higher accuracy. The illumination device 38 is preferably a surface-emitting illumination, but is not necessarily limited to surface-emitting illumination.

[0114] [Third embodiment] Fig. 16 is a schematic diagram showing the main configuration of the inner surface shape measuring instrument of the third embodiment. In Fig. 16, 200A, 200B, and 200C are a front view of the probe 30 and the two line sensor cameras 70 and 72 as seen from the Y direction, a side view as seen from the X direction, and a bottom view as seen from the Z direction, respectively.

[0115] In each of the above-described embodiments, an area sensor camera is used as the probe observation camera 32, but the third embodiment is different in that two line sensor cameras (one-dimensional sensor cameras) 70, 72 are used.

[0116] As shown in Fig. 16, the two line sensor cameras 70, 72 are cameras that capture images of linear (line-shaped) areas extending in a horizontal direction (Y direction in Fig. 16) perpendicular to the Z direction. The two line sensor cameras 70, 72 are parallel to each other and arranged at a predetermined interval in the Z direction. Similarly to the probe observation camera 32 of the first embodiment, the two line sensor cameras 70, 72 are attached to the linear motion tilt stage 18 (see Fig. 1) via a line sensor camera bracket (not shown).

[0117] An illumination device 74 is provided at a position facing the two line sensor cameras 70, 72. The probe 30 is disposed between the two line sensor cameras 70, 72 and the illumination device 74. As in the second embodiment, the illumination device 74 is attached to the linear tilt stage 18 (see FIG. 1) via an illumination device bracket (not shown). As the illumination device 74, an illumination device capable of surface emission is preferably used, but is not necessarily limited to surface emission.

[0118] In the third embodiment, the probe observation camera 32 is rotated around the rotation axis C together with the linear tilt stage 18, and the probe 30 is photographed by the two line sensor cameras 70, 72 at at least three photographing positions (preferably four photographing positions shifted by 90 degrees in the rotation direction). Then, by analyzing the photographed images taken by the two line sensor cameras 70, 72 at each photographing position, it is possible to calculate the position of the probe 30 in the photographing area of ​​each line sensor camera 70, 72. Therefore, by combining the photographed images taken by the two line sensor cameras 70, 72 at each photographing position, information (probe attitude information) equivalent to the image taken by the probe observation camera 32 in the first embodiment can be obtained, and the relative deviation between the probe 30 and the rotation axis C can be detected. Therefore, similar to the first embodiment, it is possible to perform probe alignment with high accuracy.

[0119] In the third embodiment, similarly to the second embodiment, an illumination device 74 is provided at a position facing the two line sensor cameras 70, 72, and the two line sensor cameras 70, 72 and the illumination device 74 are configured to be rotatable around the rotation axis C together with the linearly moving tilt stage 18 in a state where the probe 30 is disposed between the two line sensor cameras 70, 72 and the illumination device 74. Therefore, the probe 30 is photographed by the two line sensor cameras 70, 72 in a state where the relative positional relationship between the two line sensor cameras 70, 72 and the illumination device 74 is maintained, so that the probe 30 can be photographed under the same illumination conditions regardless of the photographing positions of the two line sensor cameras 70, 72. This makes it possible to prevent a decrease in detection accuracy due to differences in illumination conditions, and to perform probe alignment with high accuracy and ease.

[0120] [Fourth embodiment] Fig. 17 is a schematic diagram showing the main configuration of the inner surface shape measuring instrument of the fourth embodiment. In Fig. 17, 300A, 300B, and 300C respectively show a front view of the probe 30 and two line sensor cameras 70 and 72 as seen from the Y direction, a side view as seen from the X direction, and a bottom view as seen from the Z direction.

[0121] In the above third embodiment, a lighting device 74 (see FIG. 16) was provided in a position facing the two line sensor cameras 70, 72, whereas in the fourth embodiment, line laser light sources 76, 78 are provided above the line sensor cameras 70, 72, respectively.

[0122] The line laser light sources 76, 78 irradiate line lasers (line-shaped laser beams) R1, R2 onto the line-shaped imaging areas of the corresponding line sensor cameras 70, 72. The line laser light sources 76, 78 are attached to the linear motion tilt stage 18 (see FIG. 1) together with the line sensor cameras 70, 72 via brackets (not shown) for the line sensor cameras, and are rotatable around the rotation axis C together with the linear motion tilt stage 18.

[0123] In the fourth embodiment, similarly to the third embodiment, by combining images captured by the two line sensor cameras 70, 72 at each capturing position, it is possible to obtain information (probe attitude information) equivalent to the image captured by the probe observation camera 32 in the first embodiment, and to detect the relative deviation between the probe 30 and the rotation axis C. Therefore, similarly to the first embodiment, it is possible to perform probe alignment easily with high accuracy.

[0124] In addition, in the fourth embodiment, the probe 30 is photographed by the two line sensor cameras 70, 72 while maintaining the relative positional relationship between the two line sensor cameras 70, 72 and the two line laser light sources 76, 78, so that it is possible to photograph the probe 30 under the same lighting conditions regardless of the shooting positions of the two line sensor cameras 70, 72.

[0125] In addition, in Figure 17, a configuration in which two line laser light sources 76, 78 are arranged above each line sensor camera 70, 72 is shown as an example, but the positions at which the two line laser light sources 76, 78 are arranged are not particularly limited as long as they can irradiate a line laser onto the shooting area of ​​each line sensor camera 70, 72.

[0126] [Fifth embodiment] Fig. 18 is a schematic diagram showing the main configuration of the inner surface shape measuring machine of the fifth embodiment. Fig. 18 is a front view of the probe 30 and the two optical distance measuring sensors 80, 82 as viewed from the Y direction.

[0127] In each of the above embodiments, an imaging device (area sensor camera or line sensor camera) that images the probe 30 from each imaging position is used as an acquisition means for acquiring probe posture information to detect the relative deviation between the probe 30 and the rotation axis C, whereas in the fifth embodiment, two optical distance measuring sensors 80, 82 that measure distance using light are used.

[0128] As shown in Fig. 18, two optical distance measuring sensors 80, 82 are arranged at a predetermined interval in the Z direction and are attached to the linear tilt stage 18 via a bracket (not shown). The two optical distance measuring sensors 80, 82 measure distance by emitting light and detecting the reflected light. The two optical distance measuring sensors 80, 82 are sensors whose detection principle is triangulation, and for example, PSD (Position Sensitive Detector) type, CMOS (Complementary Metal-Oxide Semiconductor) type, or CCD (Charge Coupled Device) type can be applied. The detection principle of the triangulation method is well known, so a description thereof will be omitted here.

[0129] According to the fifth embodiment, the two optical distance measuring sensors 80, 82 are rotated around the rotation axis C together with the linear tilt stage 18, and the two optical distance measuring sensors 80, 82 measure the distance to the probe 30 at at least three measurement positions (preferably four measurement positions shifted by 90 degrees in the rotation direction). Then, by analyzing the relationship between the distance measured by the two optical distance measuring sensors 80, 82 at each measurement position and each measurement position, information (probe attitude information) equivalent to the image captured by the probe observation camera 32 in the first embodiment can be obtained, and the relative deviation between the probe 30 and the rotation axis C can be detected. Therefore, similar to the first embodiment, it is possible to perform probe alignment easily with high accuracy.

[0130] In the fifth embodiment, as an example of an acquisition means for acquiring probe posture information for detecting the relative misalignment between the probe 30 and the rotation axis C other than an imaging device (area sensor camera or line sensor camera), a case where two optical distance measuring sensors 80, 82 are used is shown, but any means capable of acquiring probe posture information for detecting the relative misalignment between the probe 30 and the rotation axis C may be used, and for example, a laser type, LED (Light Emitting Diode) type, ultrasonic type or eddy current type length measuring sensor may be applied.

[0131] [Application example] According to each of the above embodiments, the attitude (position and inclination) of the probe 30 with respect to the rotation axis C can be detected. Therefore, not only can the probe 30 be aligned with the rotation axis C, but also the probe 30 can be adjusted to a position inclined by a required angle. For example, as shown in FIG. 19, when measuring a tapered surface in which the inner surface of a fine hole H is inclined with respect to the rotation axis C, it is possible to set the probe angle (the inclination angle of the probe 30) according to the inclination angle (taper angle) of the tapered surface. As a result, for example, when a non-contact probe is used, the measurement light emitted from the probe 30 is irradiated from the normal direction perpendicular to the tapered surface (surface to be measured), so that more sensitive and highly accurate measurement is possible. In addition, as shown in FIG. 20, it is also possible to accurately calculate the difference in the measurement target position depending on the attitude of the probe 30.

[0132] Although the embodiment of the present invention has been described above, the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the spirit of the present invention. [Explanation of symbols]

[0133] 10... inner surface shape measuring machine, 12... main body base, 14... high-precision rotation mechanism, 16... rotating body, 18... linear motion tilt stage, 20... column, 22... carriage, 24... arm, 26... displacement detector, 28... probe linear motion tilt mechanism, 30... probe, 32... probe observation camera, 34... workpiece observation camera, 36... camera bracket, 38... lighting device, 40... lighting device bracket, 50... control device, 52... probe alignment control unit, 54... photography control unit, 56... Relative deviation detection unit, 58...probe attitude control unit, 70, 72...line sensor camera, 74...illumination device, 76, 78...line laser light source, 80, 82...optical distance measurement sensor, 100A...first captured image, 100B...second captured image, 100C...third captured image, 100D...fourth captured image, 102A...first composite image, 102B...second composite image, W...workpiece, P1...first capturing position, P2...second capturing position, P3...third capturing position, P4...fourth capturing position, C...rotation axis, K...rotation orbit

Claims

1. a stage configured to be rotatable about a rotation axis and on which a workpiece is placed, the stage having a first linear motion mechanism for linearly moving the stage within a plane perpendicular to the rotation axis; an adjustment means for adjusting the attitude of a probe for measuring the shape of the workpiece, the adjustment means having a second linear motion mechanism for linearly moving the probe within a plane perpendicular to the rotation axis; a camera coupled to the stage and movable together with the stage; A method for calibrating a measuring machine comprising: a first photographing step of acquiring a first photographed image of the probe by the camera in a state where the stage is positioned at a first linear movement position; a stage moving step of linearly moving the stage from the first linear motion position to a second linear motion position by the first linear motion mechanism; a second photographing step of acquiring a second photographed image of the probe by the camera in a state in which the stage is positioned at the second linear movement position; a probe moving step of linearly moving the probe by the second linear motion mechanism so that a position of the probe in the second photographed image is the same as a position of the probe in the first photographed image when the second photographing step is performed; a calibration step of calibrating a linear movement amount of the probe by the second linear movement mechanism based on a correspondence relationship between a linear movement amount of the stage in the stage moving step and a linear movement amount of the probe in the probe moving step; A method for calibrating a measuring machine, including:

2. the stage has a first tilt mechanism that tilts the stage with respect to a plane perpendicular to the rotation axis, the adjustment means has a second tilt mechanism that tilts the probe relative to a plane perpendicular to the rotation axis, The first photographing step includes acquiring the first photographed image by photographing the probe with the camera in a state where the stage is positioned at a first tilt position, the stage moving step causes the first tilt mechanism to tilt the stage from the first tilt position to a second tilt position; The second photographing step includes acquiring the second photographed image by photographing the probe with the camera in a state where the stage is positioned at the second tilt position, the probe moving step includes, when the second photographing step is performed, tilting and moving the probe by the second tilting mechanism so that a position of the probe in the second photographed image is the same as a position of the probe in the first photographed image; the calibration step calibrates a tilt movement amount of the probe caused by the second tilt mechanism based on a correspondence relationship between a tilt movement amount of the stage in the stage movement step and a tilt movement amount of the probe in the probe movement step; The method for calibrating a measuring machine according to claim 1.

3. a stage on which a workpiece is placed and which is configured to be rotatable around a rotation axis, the stage having a first tilting mechanism which tilts and moves the stage with respect to a plane perpendicular to the rotation axis; an adjustment means for adjusting the attitude of a probe for measuring the shape of the workpiece, the adjustment means having a second tilt mechanism for tilting and moving the probe with respect to a plane perpendicular to the rotation axis; a camera coupled to the stage and movable together with the stage; A method for calibrating a measuring machine comprising: a first photographing step of acquiring a first photographed image of the probe by the camera in a state where the stage is positioned at a first tilt position; a stage moving step of tilting the stage from the first tilt position to a second tilt position by the first tilt mechanism; a second photographing step of acquiring a second photographed image of the probe by the camera in a state in which the stage is positioned at the second tilt position; a probe moving step of tilting and moving the probe by the second tilt mechanism so that a position of the probe in the second photographed image is the same as a position of the probe in the first photographed image when the second photographing step is performed; a calibration step of calibrating an amount of tilt movement of the probe by the second tilt mechanism based on a correspondence relationship between an amount of tilt movement of the stage in the stage moving step and an amount of tilt movement of the probe in the probe moving step; A method for calibrating a measuring machine, including:

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