JP2006313120A - Approach direction setting method for probe, shape measuring apparatus program, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an approach direction setting method for a probe which can accurately set the approach direction of a probe having a contact part protruding from one end of a probe shaft part. <P>SOLUTION: To measure the surface of an object to be measured using the probe having the contact part protruding from the probe shaft part, the approach direction is set, which is a direction the contact part is brought into contact with a measurement point on the surface of the object to be measured. While the one end or the contact part of the probe shaft part is brought into contact with the outline of a true circle through a plurality of points with the direction of the contact part fixed, the probe is moved along the circumference of the true circle (a true circle measuring process ST100). The position of the probe shaft part when the one end or the contact part of the probe shaft part is brought into contact with the outline of the true circle is detected in a plane perpendicular to the probe shaft part (a detection process ST 110). On the basis of the deviation between the detected data detected in the detection process and the true circle, the approach direction is set (an approach direction setting process ST200). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a probe approach direction setting method, a shape measuring apparatus program, and a storage medium. Specifically, the present invention relates to a method for setting an approach direction for appropriately approaching a contact portion of a probe for detecting the surface of the object to be measured.

Known as measuring instruments for measuring the shape and dimensions of an object to be measured are a three-dimensional measuring instrument, a surface texture measuring instrument, a small hole measuring instrument, and the like. Such a measuring machine includes a probe that contacts the surface of the object to be measured and detects the surface of the object to be measured (for example, Patent Documents 1 and 2).
FIG. 12 is a diagram showing a conventional general probe.
As shown in FIG. 12, the conventional probe 22 includes a probe shaft portion 23 and a spherical contact portion 24 provided at the tip of the probe shaft portion 23. Then, when measuring the object surface S, the probe 22 is moved so that the contact part 24 contacts the object surface S, and the contact part 24 is in contact with the object surface S. The coordinates are detected by a predetermined detection means. Then, the position of the measurement object surface S is detected, and the surface shape or dimension of the measurement object is measured by detecting the position of the measurement object surface S at a plurality of measurement points.

  Since the conventional probe 22 has a spherical contact portion 24, it is possible to appropriately detect the object surface S even if it contacts the object surface S from any direction. However, for example, as illustrated in FIG. 13, when the shape of the small hole 30 whose diameter on the back side is enlarged by a reverse taper is a measurement target, there is a problem that the contact portion 24 cannot be handled by the spherical probe 22. That is, when the shape of the small hole 30 is to be measured, the probe shaft portion 23 contacts the inner wall of the small hole 30 before the contact portion 24 reaches the measurement point. On the other hand, in order to insert the contact portion 24 into the small hole 30, it is necessary to make the diameter of the contact portion 24 smaller than the inlet diameter of the small hole 30, so that the diameter of the contact portion 24 is simply increased. It does n’t work either.

  Therefore, when measuring the shape of such a small hole 30, the shape of the contact portion 240 is a ridge shape protruding from the probe shaft portion 230, as shown in FIG. Then, as shown in FIG. 15, the probe shaft portion 230 can abut the contact portion 24 on the back side of the small hole 30 without abutting against the inner wall of the small hole 30. Can be measured.

JP 2002-39737 A JP 2004-61322 A

  As described above, the shape of the small hole 30 can be measured by using the probe 220 having the contact portion 240 protruding from the probe shaft portion 230 in a bowl shape, and a shape that cannot be measured by the spherical contact portion 24 can be measured. .

Here, when measuring the object surface S to be measured, the contact portion 240 must be brought into contact with the measurement point on the surface S to be measured, but the contact portion 240 is only in a predetermined direction from the probe shaft portion 23. It protrudes. Therefore, in order to bring the contact portion 240 into contact with the measurement point, the direction in which the contact portion 240 protrudes from the shape measuring device is set as an approach direction, and the probe 220 is measured on the surface S of the object to be measured according to the set approach direction. We have to approach it.
However, after attaching the probe 220 to the shape measuring device, the user visually confirms the saddle-shaped contact portion 240, and then manually sets and inputs the direction in which the contact portion 240 protrudes as the approach direction. This is very difficult, and if the approach direction cannot be set accurately, the surface S to be measured is brought into contact with a portion other than the contact portion, leading to a measurement error.

  An object of the present invention is to provide a probe approach direction setting method, a shape measuring apparatus program, and a storage medium that can accurately set the approach direction of a probe having a contact portion protruding from one end of a probe shaft portion.

  The probe approach direction setting method of the present invention uses a probe having a probe shaft portion and a contact portion that is provided at one end of the probe shaft portion and projects in a direction perpendicular to the probe shaft portion with a predetermined length. A probe approach direction setting method for setting an approach direction, which is a direction in which the contact portion is in contact with a measurement point on the surface of the measurement object when measuring the surface of the measurement object, and fixing the direction of the contact portion In the true circle measuring step, the probe is moved over one round of the perfect circle while bringing one end of the probe shaft portion or the contact portion into contact with the contour of the perfect circle at a plurality of points in a state where A detecting step for detecting a position of the probe shaft portion in a plane orthogonal to the probe shaft portion when one end of the probe shaft portion or the contact portion contacts the contour of the perfect circle; Characterized in that it comprises a and approach direction setting step of setting the approach direction based on the deviation between the detected data and the perfect circle which is detected by the detecting step.

  In this configuration, since the probe has a contact portion protruding in one direction from the probe shaft portion, the probe must be brought into contact with the object to be measured in the approach direction in which the contact portion is in contact with the measurement point. I must. Therefore, this approach direction is set. In setting the approach direction, first, one round of a perfect circle is measured at a plurality of points in the true circle measurement process. At this time, the direction of the probe is fixed, that is, the probe is brought into contact with the contour of a perfect circle while the direction of the contact portion is fixed. Then, the contact portion protruding from the probe shaft portion may contact the perfect circle, or the probe shaft portion may contact the perfect circle on the back surface opposite to the side where the contact portion is provided. In some cases, the side surface of the shaft portion abuts on a perfect circle. In this way, the position of the probe shaft when the probe comes into contact with the perfect circle is detected (detection step). Then, the gap between the probe shaft and the perfect circle differs depending on whether the probe contacts the perfect circle or the probe shaft, etc. The shifted elliptical data is obtained. Therefore, the direction in which the contact portion is provided is calculated based on the amount of deviation of the detected data from the perfect circle and set as the approach direction (approach direction setting step).

According to such a configuration, since the direction of the contact portion of the probe provided with the contact portion only in one direction can be obtained and set as the approach direction, the probe is placed in the state in which the probe is directed in the approach direction. By moving to the measurement point, the contact portion can be brought into contact with the measurement point on the surface of the object to be measured.
Here, when the probe is very fine, it is difficult to visually check the direction of the contact portion, and the direction in which the contact portion is provided is set manually and input accurately. It is impossible.
In this respect, in the present invention, the approach direction is set based on the result of measuring the perfect circle, so that even if the probe is a minute probe that cannot be accurately recognized with the naked eye, the correct direction can be set as the approach direction.
Further, in setting the approach direction, it is very simple because it is only necessary to measure a perfect circle with the probe orientation fixed.

  In the present invention, the approach direction setting step is fitted to the detection data in the ellipse fitting step for fitting an ellipse to the detection data of the position of the probe shaft portion detected in the detection step, and the ellipse fitting step. A long-axis direction calculating step for calculating the long-axis direction of the ellipse, and a long-axis direction selecting step for selecting a direction toward any one of the long-axis directions calculated in the long-axis direction calculating step as the approach direction And preferably.

  In such a configuration, in the detection process, detection data deviated from the perfect circle is obtained by measuring the perfect circle with the probe orientation fixed. First, in the ellipse fitting process, the detection data is regarded as an ellipse. Fitting the ellipse equation to the detection data. In the major axis direction calculating step, the major axis direction of the ellipse is calculated. Here, the major axis direction of the ellipse is the direction in which the detection data is most deviated from the perfect circle. This is caused by contact with the reference sphere on the back surface of the lens. That is, the direction toward one of the calculated major axis directions is the direction in which the contact portion is provided, that is, the approach direction. Therefore, in the major axis direction selection step, a direction toward one of the calculated major axis directions is selected as an approach direction that is a direction in which the contact portion is provided.

  According to such a configuration, the ellipse formula is calculated after fitting the ellipse equation with the detection data as an ellipse, and therefore the direction in which the deviation from the perfect circle is the largest in the detection data, that is, The direction in contact with the perfect circle at the contact portion can be accurately obtained. Therefore, even when the probe is fine and the direction in which the contact portion is provided cannot be recognized correctly with the naked eye, the direction in which the contact portion is provided can be obtained very accurately based on the major axis direction of the ellipse.

  In the present invention, the approach direction setting step includes an inscribed circle calculating step of calculating an inscribed circle of the detection data, and the major axis direction selecting step is calculated by the inscribed circle calculated in the inscribed circle calculating step. It is preferable to select a direction from the far end of the major axis of the ellipse as viewed from the center of the circle toward the center of the inscribed circle as the approach direction.

In such a configuration, the inscribed circle of the detection data is calculated in the inscribed circle calculating step.
Here, the detection data is deviated from the perfect circle depending on whether the probe abuts at one end of the probe shaft portion or the contact portion with respect to the perfect circle. The circle is considered to be a circle having the same center point as that of the perfect circle to be measured without being affected by the deviation. In the long axis direction selecting step, the direction from the far end of the long axis end points of the ellipse toward the center point of the inscribed circle is selected as the approach direction. That is, the point far from the center point of the inscribed circle is a point far from the center point (distant point) due to the contact part being interposed between the perfect circle and the probe shaft part. The tip of the contact portion is in contact with a perfect circle. Therefore, the approach direction can be set by selecting the direction from the far point toward the center of the inscribed circle as the approach direction. According to such a configuration, since the approach direction is automatically recognized based on the relationship between the center of the inscribed circle and the long point in the long axis direction, the setting of the approach direction becomes simple and accurate.

  In the present invention, the approach direction setting step includes a display step of displaying the ellipse fitted to the detection data in the ellipse fitting step and the major axis direction calculated by the major axis direction calculation unit on a display unit. In the long axis direction selection step, it is preferable that the approach direction is selected based on a determination when the shape of the ellipse displayed on the display means is visually recognized.

  According to such a configuration, since the approach direction is recognized from the shape of the ellipse displayed on the display means in the display step, for example, there is a lot of noise in the detection data, and automatic recognition based on the detection data is difficult. In addition, the approach direction can be appropriately set based on the judgment of the operator.

  In the present invention, the approach direction setting step includes a general direction setting step of setting in advance whether the approach direction is a plus direction or a minus direction on the coordinate system when the orientation of the contact portion is fixed in the perfect circle measurement step. It is preferable that the major axis direction selection step sets one of the major axis directions as the approach direction according to the direction set in the general direction setting step.

  According to such a configuration, since the direction of the contact portion is set in advance in the approximate direction setting step, the approach direction can be easily selected from the major axis directions of the ellipse fitted to the detection data.

  The shape measuring device of the present invention includes a probe having a probe shaft portion and a contact portion provided at one end of the probe shaft portion and projecting with a predetermined length in one direction orthogonal to the probe shaft portion. A shape measuring device for measuring a surface shape of the object to be measured based on a probe position when the part comes into contact with the surface of the object to be measured, wherein one end of the probe shaft part is fixed in a state in which the orientation of the contact part is fixed Or a perfect circle measuring means for moving the probe over one round of the perfect circle while bringing the contact portion into contact with the contour of the perfect circle at a plurality of points, and one end of the probe shaft part or the contact part is the perfect circle A detecting means for detecting a position of the probe shaft portion in contact with the contour in a plane orthogonal to the probe shaft portion, and the approach based on a deviation between the detection data detected by the detecting means and the perfect circle. direction Characterized in that it comprises a and approach direction setting means for setting.

  The probe approach direction setting program includes a probe having a probe shaft portion and a contact portion that is provided at one end of the probe shaft portion and protrudes at a predetermined length in one direction orthogonal to the probe shaft portion. A computer is incorporated in a shape measuring device that measures the surface shape of the object to be measured based on the probe position when the part contacts the surface of the object to be measured, and the computer is in a state where the orientation of the contact part is fixed. A perfect circle measuring means for moving the probe over one circumference of the perfect circle while bringing one end of the probe shaft part or the contact part into contact with the contour of a perfect circle at a plurality of points; and one end of the probe shaft part or the contact Detecting means for detecting the position of the probe shaft portion in a plane orthogonal to the probe shaft portion when the portion comes into contact with the contour of the perfect circle, and detected by the detection means And approach direction setting means for setting the approach direction based on the deviation between the output data and the true circle, characterized in that to function with.

  The recording medium of the present invention records the above-described probe approach direction setting program.

  According to such a configuration, the same effects as those of the above-described invention can be achieved.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be illustrated and described with reference to reference numerals attached to respective elements in the drawings.
(First embodiment)
A first embodiment of the probe approach direction setting method of the present invention will be described.
First, as a premise for explaining the approach direction setting method of the probe, the configuration of the shape measuring apparatus 100 including the probe 220 will be described.
FIG. 1 is a diagram illustrating a configuration of the shape measuring apparatus 100.
The shape measuring apparatus 100 includes a coordinate measuring machine 200, an operation unit 300 having a joystick 310 that is manually operated, a motion controller 400 that controls the operation of the coordinate measuring machine 200, and the coordinate measuring machine via the motion controller 400. 200 includes a host computer 500 that operates the measurement data obtained by the coordinate measuring machine 200 and obtains the size and shape of the workpiece W, an output unit 610, and an input unit 620.

  The three-dimensional measuring machine 200 includes an excitation contact sensor 210 that detects the surface S of the object W to be measured, a drive mechanism 260 that three-dimensionally drives the excitation contact sensor 210, and an object to be measured. And a surface plate 270 to be placed.

FIG. 2 is a diagram illustrating a configuration of the vibration contact sensor 210.
The vibration contact sensor 210 includes a probe 220, a probe holder 250 that supports the probe 220, a piezoelectric element 251 that is provided in the probe holder 250 and vibrates the probe 220 in the axial direction, and a probe that is connected to the piezoelectric element 251. An excitation circuit 252 that applies a signal having a natural frequency of 220 (such as a pulse or sine wave signal), a piezoelectric element 253 that converts a vibration change of the probe 220 into a voltage change, and a voltage change from the piezoelectric element 253. And a detection circuit 254 that detects and outputs a detection signal.

The probe 220 includes a probe shaft portion 230 and a contact portion 240 provided at one end of the probe shaft portion 230.
The cross-sectional shape of the probe shaft 230 is circular.
The contact portion 240 protrudes in one direction orthogonal to the probe shaft portion 230 at one end of the probe shaft portion 230.
The shape of the contact portion 240 is a saddle shape and is a tapered shape that tapers toward the tip 241. The tip 241 contacts the surface S of the object to be measured at one point and is convex so as not to damage the contact point. It is finished to a spherical surface.
Here, the shape of the contact portion 240 is measured by, for example, an image measuring device, and the height (Z-direction position) of the tip 241 is obtained.
Furthermore, when measuring the workpiece surface S, the contact portion 240 must be brought into contact with the workpiece surface S, and an approach direction that is the direction in which the contact portion 240 protrudes from the shape measuring apparatus 100 is set. This point will be described later with reference to the flowchart of FIG.

  The drive mechanism 260 has two heights from both side ends of the surface plate 270 in the Zm direction that is substantially perpendicular to the surface plate 270 and is slidable in the Ym axis direction along the side edge of the surface plate 270. A beam support 261, a beam 262 supported on the upper end of the beam support 261 and having a length in the Xm direction, a column 263 provided on the beam 262 so as to be slidable in the Xm direction, and having a guide in the Zm axis direction, A spindle 264 that is slidable in the Z-axis direction in the column 263 and holds the vibration-type contact sensor 210 at the lower end. The amount of movement of the beam support 261 in the Ym-axis direction, the amount of movement of the column 263 in the Xm-axis direction, and the amount of movement of the spindle 264 in the Zm-axis direction are detected by predetermined drive sensors.

  A reference sphere 280 that is a true sphere is disposed on the surface plate 270 of the coordinate measuring machine 200.

  The motion controller 400 counts detection signals from the drive sensors to detect the position of the vibration contact sensor 210 and controls the drive mechanism 260 in accordance with commands from the host computer 500 and the operation unit 300.

The host computer 500 issues an operation command for the coordinate measuring machine 200 based on preset measurement conditions, and analyzes the shape of the surface of the object to be measured based on the detection signal from the drive sensor. Further, when the host computer 500 moves the vibration contact sensor 210 toward the surface to be measured S, the host computer 500 vibrates in the approach direction that is the direction in which the contact portion 240 abuts the surface S to be measured. The direction of the type sensor 210 is controlled.
The approach direction is stored in the approach direction control unit 510, and the step of setting the approach direction in the approach direction control unit 510 will be described later with reference to the flowchart of FIG.

  The output means 610 is exemplified by a display means and a printer, and the input means 620 is exemplified by a keyboard.

An operation for measuring the surface S of the object to be measured by the shape measuring apparatus 100 having such a configuration will be described.
In detecting the measurement object surface S, the vibrating contact sensor 210 is moved toward the measurement object surface S.
However, the direction of the vibrating contact sensor 210 is set to a direction (approach direction) in which the contact portion 240 contacts the surface of the object to be measured.
At this time, the detection signal changes as shown in FIG. 3 due to the positional relationship between the contact portion 240 and the surface S of the object to be measured. When the contact part 240 starts to contact the surface of the object to be measured from the state where the contact part 240 is free (A) (B), and the contact part 240 contacts the surface of the object to be measured with a predetermined pushing amount d (C), The vibration of the contact portion 240 is constrained and the detection signal reaches a preset reference value.
Here, the reference value is obtained by subtracting the signal change when the contact portion 240 is pushed by the predetermined push amount d from the detection signal value detected when the contact portion 240 is free (non-contact state). It is set in advance.

The contact portion 240 is pressed against the surface S of the object to be measured so that the detection signal value becomes the reference value, and the position information of the vibration type contact sensor 210 when the detection signal reaches the reference value is indicated by X of the drive mechanism 260. , Sample from Y, Z axis slide amount.
Such contact and separation are repeated and the surface of the object to be measured is measured at a plurality of points. Then, the shape of the surface S of the object to be measured can be known from the sampled positional information of the vibration type contact sensor 210.

(Approach direction setting method)
Next, an approach direction setting method for setting the approach direction, which is the direction in which the contact portion 240 abuts the measurement point on the surface S of the workpiece, in the approach direction control unit 510 will be described with reference to the flowchart of FIG.
Here, FIG. 5 is a diagram illustrating a configuration of the approach direction control unit 510. The approach direction control unit 510 includes a perfect circle measurement unit 520, a detection data storage unit 530, an approach direction setting unit 540, and an approach direction. The approach direction setting unit 540 includes an ellipse fitting unit 541, a long axis direction calculating unit 542, an inscribed circle calculating unit 543, and a long axis direction selecting unit 544.

After attaching the vibration contact sensor 210 to the tip of the spindle 264, the approach direction controller 510 sets and stores the approach direction of the vibration contact sensor 210.
In setting the approach direction, first, in ST100, the true circle measuring step is executed by the true circle measuring unit 520.
In this perfect circle measurement step (ST100), as shown in FIG. 6, the vibration contact sensor 210 is brought into contact with the contour of the perfect circle, which is the equator portion of the reference sphere 280, at a plurality of points.

  At this time, the orientation of the contact portion 240 is fixed. That is, when the vibration contact sensor 210 is brought into contact with the reference sphere 280, only the drive mechanism 260 is driven to move the vibration contact sensor 210 without rotating the spindle 264, and the probe shaft 230 is moved. One end of the lens is brought into contact with the reference sphere 280. Then, the tip 241 of the contact portion 240 comes into contact with the reference sphere 280 on one side, whereas the back surface of the probe shaft portion 230 comes into contact with the reference sphere 280 on the opposite side, and at another position, The side surface of the portion 230 comes into contact with the reference sphere 280.

  Then, the vibration contact sensor 210 abuts on the reference sphere 280 to restrain the vibration of the probe 220, and the detection circuit 254 detects that the detection signal from the detection circuit 254 has reached a predetermined reference value. Then, the position of the vibration type contact sensor 210 is detected by the drive sensor (detection step ST110). This detection data is stored in the detection data storage unit 530.

  Here, the detection circuit 254, the drive sensor, and the detection data storage unit 530 constitute detection means.

FIG. 7 is an example of the detection data D obtained in this way.
Since the direction of the vibration contact sensor 210 is constant, when the contact portion 240 contacts the reference sphere 280 depending on whether the contact portion 240 contacts the reference sphere 280 or the probe shaft portion 230 contacts the reference sphere 280. The degree to which the position of the probe shaft portion 230 deviates from a perfect circle is different. Therefore, the detection data D has a substantially elliptical shape that deviates from the perfect circle of the reference sphere 280.
That is, when the position of the probe shaft portion 230 is detected when the contact portion 240 abuts on the reference sphere 280, the reference sphere 280 corresponding to the amount of the contact portion 240 interposed between the reference sphere 280 and the probe shaft portion 230 is detected. The deviation from is increased (A in FIG. 7). On the other hand, if the probe shaft 230 is in contact with the reference sphere 280, detection data with a small deviation from the reference sphere 280 is obtained (B in FIG. 7).

  When the vibration contact sensor 210 is brought into contact with the circumference of the reference sphere 280 and measurement for one round is completed (ST120: YES), the approach direction is then based on the deviation between the detection data D and the perfect circle. The approach direction setting step (ST200) is performed by the approach direction setting unit 540.

In the approach direction setting step (ST200), first, an elliptical fitting step is executed by the elliptical fitting unit 541 in ST210.
The detection data D obtained in the detection step (ST110) has a shape deviated from a perfect circle depending on which of the probe shaft part 230 and the contact part 240 is in contact with the reference sphere 280. In the ellipse fitting step, the detection data D is recognized as an ellipse, and the ellipse E is fitted to the detection data D (see FIG. 8).

Next, in ST220, the long-axis direction calculating unit 542 executes a long-axis direction calculating step for calculating the long-axis direction L of the ellipse E fitted to the detection data D.
Thereby, the major axis direction L is calculated from the equation of the ellipse E calculated in the ellipse fitting step (ST210).
Here, the major axis direction of the ellipse E is the direction in which the detection data D is most deviated from the perfect circle, and this deviation is caused by the reference contact 280 at the tip 241 of the contact portion 240 on the one side. This is caused by the contact with the reference sphere 280 on the back side of the probe shaft 230 on the opposite side. That is, the direction toward one of the calculated major axis directions L is the direction in which the contact portion 240 is provided, that is, the approach direction.

  Next, in ST230, an inscribed circle calculation step for calculating the inscribed circle C of the detection data D is executed by the inscribed circle calculation unit 543, and the inscribed circle C of the detected data D is calculated. For example, as shown in FIG. 9, the inscribed circle C of the detection data D is obtained, and at the same time, the center point O of the inscribed circle C is calculated.

In ST240, the long axis direction selecting unit 544 executes a long axis direction selecting step of selecting any one of the long axis directions calculated in the long axis direction calculating step (ST220) as the approach direction.
At this time, when viewed from the center of the inscribed circle C calculated in the inscribed circle calculating step (ST230), the far end (far point B) of the end points of the major axis L of the ellipse E is changed to the center O of the inscribed circle C. The direction to go is selected as the approach direction V.
For example, in FIG. 9, where a point T and a point B exist as points on the ellipse in the major axis direction, the direction from the point B far from the center of the inscribed circle C to the center O is selected as the approach direction V.

  In ST300, the approach direction is set and stored in approach direction storage section 550. In other words, the approach direction storage unit 550 stores that the direction in which the contact portion 240 is provided is the approach direction V in the current state where the vibration type contact sensor 210 is attached to the spindle 264.

Actually, when detecting the surface S of the object to be measured by the vibration type contact sensor 210, first, the shape of the object to be measured based on the design data of the object to be measured is set and inputted to the host computer 500. Further, a predetermined number of measurement points are set on the surface of the object to be measured.
Then, the normal direction of the surface S of the object to be measured at this measurement point is set as the moving direction of the vibration contact sensor 210, and the vibration contact sensor 210 is brought closer to the measurement point. At this time, the spindle 264 is rotated so that the contact portion 240 faces the measurement point. That is, the approach direction V is directed to the measurement point.
In this way, when the contact portion 240 is in the state of being directed to the measurement point, the vibration type contact sensor 210 is brought close to the measurement point by the driving mechanism 260, and the vibration is restrained when the contact portion 240 comes into contact with the measurement point. Based on the detection signal, contact between the contact portion 240 and the surface of the object to be measured is detected, and the position of the vibration type contact sensor 210 at this time is detected by the drive sensor. Based on the detection data thus obtained, the host computer 500 analyzes the shape of the surface of the object to be measured.
Furthermore, when the shape of the contact portion 240 is accurately known, the coordinates of the surface of the object to be measured may be accurately calculated by correcting the amount of the contact portion from the probe axis position.

According to 1st Embodiment provided with such a structure, there can exist the following effects.
(1) Since the direction of the contact part 240 of the vibration type contact sensor 210 in which the contact part 240 is provided only in one direction can be obtained and set as the approach direction V by the approach direction setting method, the approach direction is a measurement point. The contact portion 240 can be brought into contact with the measurement point on the surface S of the object to be measured by moving the vibrating contact sensor 210 to the measurement point of the object W to be measured. Thereby, the to-be-measured object surface S is detectable. For example, the shape of a small hole that could not be measured with the conventional spherical contact portion 240 can be measured.

(2) Even when the probe 220 is very fine and it is difficult to confirm with the naked eye which direction the contact portion 240 is, based on the result of measuring the reference sphere 280 with the approach direction setting method. Thus, the approach direction V can be set, so that an accurate direction can be set as the approach direction V. In setting the approach direction V, the reference sphere 280 is only measured in a state where the orientation of the probe 220 is fixed (round measurement step ST100), which is very simple.

(3) Since the ellipse E is fitted with the detection data D as the ellipse E and the major axis L of the ellipse E is calculated (major axis direction calculation step ST220), the deviation from the perfect circle is the most in the detection data D. The direction of increasing, that is, the direction of contact with the reference sphere 280 at the tip 241 of the contact portion 240 can be accurately obtained. Therefore, even when the probe 220 is fine and the direction in which the contact portion 240 is provided cannot be recognized correctly with the naked eye, the direction in which the contact portion 240 is provided based on the major axis direction L of the ellipse E is very accurate. Can be sought.

(4) After calculating the long axis direction L of the ellipse E in the long axis direction calculating step (ST220), the center O of the inscribed circle C calculated in the inscribed circle calculating step (ST230) and the long axis direction L are further calculated. Since the approach direction is automatically recognized based on the relationship with the far point B, the approach direction can be set easily and accurately even when the direction of the contact part 240 cannot be visually recognized with the naked eye.

In addition, this invention is not limited to the said embodiment, The deformation | transformation in the range which can achieve the objective of this invention, improvement, etc. are included in this invention.
In the above embodiment, after calculating the long axis direction in the long axis direction calculating step (ST220), the inscribed circle of the detection data is further calculated in the inscribed circle calculating step (ST230). The case where the approach direction V is automatically recognized from the relationship between the end point B and the center O of the inscribed circle C has been described. In addition, for example, after calculating the long axis direction L in the long axis direction calculating step (ST220), the operator determines and selects which direction of the long axis direction L is set as the approach direction V. Also good. In this case, for example, the ellipse E obtained in the ellipse fitting step (ST210) and the long axis L calculated in the long axis direction calculation step (ST220) are displayed on the display means, and then the ellipse is displayed on the display screen. The operator may select the approach direction from the state of eccentricity.

  Alternatively, when the direction in which the contact part 240 of the probe 220 is provided can be confirmed with the naked eye, the direction in which the contact part 240 is provided may be set in advance in the approximate range. For example, it is input whether the direction in which the contact part 240 is provided is the plus side or the minus side on the coordinate system. Then, the direction input in advance among the major axis directions calculated in the major axis direction calculating step (ST220) may be set as the approach direction.

In the above embodiment, the case where the perfect circle measured in the true circle measurement step (ST100) is the outline of the reference sphere 280 has been described as an example. However, since it may be a perfect circle, for example, it is cylindrical. Of course, the side surface of the pin gauge may be measured.
Alternatively, if the reference object is not limited to a perfect circle and has a known shape in advance, the circumference of the reference object is measured in a state where the orientation of the probe 220 is fixed, and the difference between the shape of the reference object and the detection data is detected. Based on this, the orientation of the contact portion 240 may be determined.

  Although the case where the cross section of the probe shaft portion 230 is circular has been described in the above embodiment, the cross sectional shape of the probe shaft portion 230 is not limited to a circle. For example, the cross section of the probe shaft portion 230 may be polygonal, for example, the cross section of the probe shaft portion 230 may be square as shown in FIG. In this case, when a perfect circle is measured in a state where the orientation of the probe 220 is fixed in the true circle measurement step (ST100), as shown in FIG. 11, a shoulder portion appears compared to the detection data shown in FIG. However, even in this case, since the major axis direction can be calculated, the approach direction can be obtained.

In the above embodiment, the vibration type that detects that the probe 220 has come into contact with the measurement object surface S from the change in the detection signal when the probe 220 comes into contact with the measurement object surface S by vibrating the probe 220. Although the contact type sensor 210 has been described as an example, the configuration for detecting that the probe 220 is in contact with the surface to be measured S is not limited to the above embodiment.
For example, while the contact portion 240 is pressed against the surface of the workpiece S so that the detection signal becomes a reference value with the vibration type contact probe 210, the contact portion 240 is moved along the surface of the workpiece S while being moved. The measurement object surface S may be detected.
Alternatively, the touch trigger measurement may be performed by a scanning probe that can hold the probe so as to be slidable and can detect the pressing amount of the probe, or the scanning measurement may be performed.

  The present invention can be used for a shape measuring apparatus.

The figure which shows the structure of a shape measuring apparatus. The figure which shows the structure of a vibration type contact type sensor. The figure which shows the relationship between the amount of pushing of a contact part, and a detection signal. The flowchart which shows the process sequence of the approach direction setting method. The figure which shows the structure of an approach direction control part. The figure which shows a mode that a reference | standard sphere is measured in a perfect circle measurement process. The figure which shows an example of detection data. The figure which shows the ellipse fitted to the detection data. The figure which shows the inscribed circle of detection data. The figure which shows the probe whose probe axis is a quadrangular prism shape. The figure which shows an example of the detection data in case a probe axis | shaft is square pillar shape. The figure which shows the conventional probe whose contact part is spherical. The figure which shows a mode that the small hole which expands by reverse taper is measured with the conventional probe. The figure which shows the probe whose contact part is a saddle type. The figure which shows a mode that a small hole is measured with the probe whose contact part is a saddle type.

Explanation of symbols

DESCRIPTION OF SYMBOLS 22 ... Probe, 23 ... Probe axial part, 24 ... Contact part, 30 ... Small hole, 100 ... Shape measuring apparatus, 200 ... CMM, 210 ... Excitation type contact sensor, 220 ... Probe, 230 ... Probe axis , 240 ... contact part, 241 ... tip of contact part, 250 ... probe holder, 251 ... piezoelectric element, 252 ... excitation circuit, 253 ... piezoelectric element, 254 ... detection circuit, 260 ... drive mechanism, 261 ... beam support 262 ... Beam, 263 ... Column, 264 ... Spindle, 270 ... Surface plate, 280 ... Reference sphere, 300 ... Operation unit, 310 ... Joystick, 400 ... Motion controller, 500 ... Host computer, 510 ... Approach direction control unit, 520 ... perfect circle measurement unit, 530 ... detection data storage unit, 540 ... approach direction setting unit, 541 ... ellipse fitting unit 542 ... major axis direction calculation section, 543 ... inscribed circle calculating section, 544 ... major axis direction selection unit, 550 ... approach direction storage section, 610 ... Output section, 620 ... input means.

Claims (8)

In measuring the surface of the object to be measured using a probe shaft and a probe having a contact portion provided at one end of the probe shaft and projecting in a predetermined direction in a direction orthogonal to the probe shaft, A probe approach direction setting method for setting an approach direction, which is a direction in which a contact portion is in contact with a measurement point on the surface of the object to be measured,
A perfect circle measuring step of moving the probe over one round of the perfect circle while bringing one end of the probe shaft or the contact part into contact with the contour of the perfect circle at a plurality of points with the orientation of the contact portion fixed; ,
A detecting step for detecting a position of the probe shaft portion in a plane perpendicular to the probe shaft portion when one end of the probe shaft portion or the contact portion abuts on a contour of the perfect circle in the perfect circle measuring step;
An approach direction setting step of setting the approach direction based on a deviation between the detection data detected in the detection step and the perfect circle. An approach direction setting method for a probe, comprising: The approach direction setting method of the probe according to claim 1,
The approach direction setting step includes:
An ellipse fitting step of fitting an ellipse equation to the detection data of the position of the probe shaft portion detected in the detection step;
A long axis direction calculating step of calculating a long axis direction of the ellipse fitted to the detection data in the elliptic fitting step;
A probe approach direction setting method, comprising: a major axis direction selecting step of selecting a direction toward one of the major axis directions calculated in the major axis direction calculating step as the approach direction. . The probe approach direction setting method according to claim 2,
The approach direction setting step includes:
An inscribed circle calculating step of calculating an inscribed circle of the detection data,
In the long axis direction selection step, the direction from the far end of the long axis of the ellipse toward the center point of the inscribed circle as seen from the center of the inscribed circle calculated in the inscribed circle calculation step is A method for setting the approach direction of the probe, characterized by being selected as the approach direction. The probe approach direction setting method according to claim 2,
The approach direction setting step includes a display step of displaying the ellipse fitted to the detection data in the ellipse fitting step and the major axis direction calculated by the major axis direction calculation unit on a display unit,
The approach direction setting method, wherein, in the long axis direction selection step, the approach direction is selected based on determination when the shape of the ellipse displayed on the display means is visually recognized. The probe approach direction setting method according to claim 2,
The approach direction setting step includes:
An approximate direction setting step for presetting whether the approach direction is a plus direction or a minus direction on the coordinate system when the orientation of the contact portion is fixed in the perfect circle measurement step;
The probe approach direction setting method, wherein the major axis direction selecting step sets one of the major axis directions as the approach direction according to the direction set in the approximate direction setting step. And a probe having a probe shaft portion and a contact portion provided at one end of the probe shaft portion and projecting at a predetermined length in one direction orthogonal to the probe shaft portion, and the contact portion contacts the surface of the object to be measured. A shape measuring device for measuring a surface shape of the object to be measured based on a probe position when contacting,
A perfect circle measuring means for moving the probe over one round of the perfect circle while abutting one end of the probe shaft part or the contact part with a contour of a perfect circle at a plurality of points in a state where the orientation of the contact part is fixed; ,
Detecting means for detecting a position of the probe shaft portion in a plane orthogonal to the probe shaft portion when one end of the probe shaft portion or the contact portion comes into contact with the contour of the perfect circle;
A shape measuring apparatus comprising: an approach direction setting unit that sets the approach direction based on a deviation between the detection data detected by the detection unit and the perfect circle. And a probe having a probe shaft portion and a contact portion provided at one end of the probe shaft portion and projecting at a predetermined length in one direction orthogonal to the probe shaft portion, and the contact portion contacts the surface of the object to be measured. Incorporating a computer into a shape measuring device that measures the surface shape of the object to be measured based on the probe position at the time of contact,
A perfect circle measuring means for moving the probe over one round of the perfect circle while abutting one end of the probe shaft part or the contact part with a contour of a perfect circle at a plurality of points in a state where the orientation of the contact part is fixed; ,
Detecting means for detecting a position of the probe shaft portion in a plane orthogonal to the probe shaft portion when one end of the probe shaft portion or the contact portion comes into contact with the contour of the perfect circle;
An approach direction setting of a computer-readable probe, which functions as an approach direction setting means for setting the approach direction based on a deviation between detection data detected by the detection means and the perfect circle. program.   A recording medium recording the probe approach direction setting program according to claim 7.

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