JP3536013B2 - Surface shape measurement method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface shape measuring method for measuring the surface shape of an object to be measured by a contact type probe attached to a coordinate measuring machine or the like, and particularly when using an ultrasonic vibration type contact detecting probe. The improvement of measurement efficiency and accuracy.

[0002]

BACKGROUND ART Height gauges (one-dimensional measuring instruments), three-dimensional measuring instruments, and contour measuring instruments are known as measuring instruments for measuring the shape and dimensions of an object to be measured. These measuring instruments include
Various probes are used to detect the positional relationship between the measuring device body and the object to be measured. These probes are classified into non-contact type probes and contact type probes, or continuous measurement probes and contact detection probes (touch trigger probes). An ultrasonic touch signal probe disclosed in Japanese Patent Laid-Open No. 6-221806 is known as a contact detection probe for a coordinate measuring machine.

The touch signal probe disclosed in the above publication has a stylus having a contact portion at the tip for contacting an object to be measured, and a stylus holder for supporting the stylus.
It includes a vibrating means for resonating the stylus in the axial direction, and a detecting means for detecting a change in vibration of the stylus by the vibrating means. According to such a touch signal probe, when the tip portion is brought into contact with the end surface of the object to be measured while the stylus is vibrated by the vibrating means, the vibrating state of the stylus changes due to the contact force. The end face position of the object to be measured can be detected by the detection means.

[0004] Such an ultrasonic touch signal probe may be used to measure the small hole diameter and the like. As an ultrasonic touch signal probe that has been downsized in order to make it possible to measure the small hole and the like. The touch signal probe disclosed in Japanese Patent Application No. 10-220474 has been proposed. As shown in FIG. 12, the touch signal probe 100 includes a stylus holder 101, a stylus 102, a vibrating means 103A, and a detecting means 103B. The stylus 102 has a contact portion 102A at the tip thereof which comes into contact with the object to be measured, and a counter balance 102B at the base end thereof.
Is provided, and the center position of the stylus 102 in the axial direction is the center of gravity position. When the stylus 102 is vibrated in the axial direction, the node of vibration is at this barycentric position.

Such a touch signal probe 100 is
In order to enable the measurement of small holes, the stylus 102 is formed of a thin rod-shaped member, and the contact portion 102A is formed of a small-diameter spherical body so as to fit the stylus 102. Further, since it is difficult for the stylus holder 101 to support such a thin stylus 102 at one place, the stylus holder 101 supports the stylus 102 at two places with the center of gravity of the stylus 102 interposed therebetween.

Exciting means 103A and detecting means 103B
Is configured by dividing the piezoelectric element 103, which is arranged so as to straddle two supporting portions of the stylus holder 101, into two. Then, the stylus 1 is moved by the vibrating means 103A.
When 02 is resonated along the axial direction, a vibration node is generated at the center of gravity of the stylus 102, and the stylus holder 10
The supporting portion of the stylus 102 of No. 1 is positioned so as to sandwich this vibration node.

According to such a touch signal probe 100, since the stylus holder 101 supports the stylus 102 at two places across the vibration node, even if the stylus 102 is formed of an extremely thin rod-shaped member, It can be supported by the holder 101, and the inner surface of a small hole having a large aspect ratio can be measured.

On the other hand, a method (tapping method) of contacting the surface of the object to be measured with a vibration operation has also been developed (Japanese Patent Application No. 11-96377, etc.). In this method, for example, the stylus holder 101 described above is provided with a second vibrating means, the vibrating means vibrates the stylus 102, and vibrates the contact portion 102A at the tip of the stylus 102 toward and away from the object to be measured. It is what makes me. According to such a tapping method, even if the stylus 102 is moved along the surface of the object to be measured to continuously measure the surface shape, the contact portion 10
Since 2A is spaced apart from the object to be measured, it is possible to avoid dragging (adhesion phenomenon) due to the object to be measured even if the stylus 102 has a low rigidity. Therefore, there is an effect that working efficiency can be improved by continuous measurement while maintaining high accuracy.

[0009]

However, in the above-mentioned ultrasonic vibration type touch signal probe, the timing of outputting the contact detection trigger determines the measurement accuracy. That is,
When the stylus vibrated by the vibrating means approaches the object to be measured and the contact portion comes into contact with the surface of the object to be measured, the vibration is suppressed at the time when the contact starts. Then, the stylus is further suppressed because the contact portion and the surface of the object to be measured come into contact with each other with a certain pressure contact force. At this time, since there is a correlation between the pressing state against the surface of the object to be measured and the vibration suppression state, if the output signal of the detection means is monitored and it is determined that the vibration suppression has reached the predetermined level, The amount of the stylus pushed into the object to be measured is constant, and accurate position detection is possible.

However, in order to measure the position of one point on the surface of the object to be measured, repetitive work such as detecting the stylus by moving it close to and away from the stylus at that position is necessary. is there. In particular, in the case of inspecting a large number of points such as continuous measurement of the surface of the object to be measured, the total work time may be enormous. On the other hand, when measuring the position of each point of the measured object, the working time can be shortened if the vibration state of the stylus is not strictly converged at that position but is converged within a predetermined range. Of course, in this case, the measurement accuracy is inferior.

An object of the present invention is to provide a surface shape measuring method capable of avoiding the influence of the convergence time at each contact point of an object to be measured in the vibration type contact detection and maintaining the measurement accuracy at a high level and improving the work efficiency. Especially.

[0012]

According to the present invention, in the conventional vibrating contact detection, the stylus is moved to a position where the vibration state of the stylus becomes a predetermined state, and the stylus position information at this position is read to determine the contact position. The calculation was performed, and it was noted that the complexity of finely separating and separating the stylus was the convergence time for this purpose. Then, instead of actually allowing the stylus to settle at a predetermined position, information on the predetermined position that should be settled in the past should be calculated from the information from the detection means obtained in the vicinity and the stylus position information. The position of the surface of the object to be measured can be measured accurately and efficiently.

Specifically, a support which moves in a three-dimensional space at a predetermined command velocity vector by a command from the outside,
A stylus supported by the support and having a contact portion for contacting an object to be measured, a vibrating means for resonating the stylus at a frequency f1 in the axial direction, and a change in vibration of the stylus by the vibrating means are detected. Using a contact detection probe provided with a detection means, a surface shape measuring method for measuring the surface shape of the measured object from the position of the support when the contact portion contacts the surface of the measured object, According to the command of the command velocity vector, the step of moving the contact detection probe to contact the surface to be measured of the object to be measured, the amplitude information value An of the detection signal output from the detection circuit is predetermined reference information. While controlling the distance to the surface to be measured so that the value A _s , the contact detection probe is moved along the surface to be measured, the amplitude information value
An a step of scanning the surface to be the measurement by slide into outputs real position r _n corresponding thereto, from the real position r _n corresponding thereto and the amplitude information values An, the amplitude information value An is a constant It is characterized by including a step of calculating an estimated surface position R _n which is estimated to be obtained when scanning is performed so that

As the contact detection probe, the above-mentioned ultrasonic vibration type touch signal probe or the like can be used. The stylus may have a structure supported through a stylus holder connected to the support. An existing driving element such as a piezoelectric element can be appropriately used as the vibrating means.
A power source and a driving circuit may be connected to the outside in order to operate the vibrating means. The detecting means can also be composed of a piezoelectric element, and an existing structure such as a structure integrated with the vibrating means can be appropriately adopted. The drive of the support may depend on an existing coordinate measuring machine, and the operation may be performed based on a command program executed by an external controller or a computer system. Amplitude information value from detection means
Collection of An, control along reference information value As, estimated surface position R _n
Can be executed by these external controllers or computer systems. Amplitude information value An, actual position r _n collection and estimated surface position in the scanning process
The calculation of R _n may be performed in parallel, or each step may be sequentially performed as described later. Performing in parallel means calculating the estimated surface position R _n-2 from the amplitude information value An _-2 and the actual position r _n-2 several steps before while detecting the r _n position by an external computer or the like. Means to perform

In such a structure, after the stylus is brought into contact with the surface of the object to be measured, the amplitude information value An and the actual position r _n of each point are collected by scanning the surface, and the estimation of each point is performed from these. The surface position R _n is calculated. At this time, although the stylus is controlling the distance between the surface so that the amplitude information value An of each point becomes the reference information value A _s, the amplitude information value An is the reference information value
Not stay at each point to converge to A _s, not take convergence time as in the conventional. On the other hand, the estimated surface position of each point
R _n is the actual position r _n can be derived in a manner to correct the amplitude information values An, that the stylus is to obtain an accurate value even without reaching the position of the amplitude information values An = reference information value A _s it can.

In the present invention, the commanded velocity vector V _{n + 1} in the scanning step is the previous value V _n and the V _{n + 1.}
It is determined by the difference in the proportionality constant k times the value equivalent to the scalar vector product between the amplitude information values An and the reference information value A _s with desirable. Thus, it is possible to perform control to move the stylus so that the amplitude information value An of the aforementioned approaches the reference information value A _s easily and appropriately.

[0017] In the present invention, the estimated surface position R _n which is calculated in the step of the operation, after determining the next actual position r _{n + 1} with respect to the actual position r _n, the actual position r _n As a starting point,
The size corresponding to the amplitude information value An, and the next actual position
It can be a position corrected in a direction orthogonal to a straight line connecting r _{n + 1} and the previous actual position r _{n -1} . By doing so, the estimated surface position R _n can be obtained with high accuracy by a simple calculation.

The estimated surface position R _n calculated in the calculating step has the actual position r _n as a starting point and has a size corresponding to the amplitude information value An, and the actual position r _n and one It can be a position corrected in a direction orthogonal to the straight line connecting the previous actual position r _n-1 . By doing so, the next actual position r _{n + 1} is not necessary, so that the detected data can be immediately processed.

Further, the estimated surface position R _n calculated in the calculating step starts from the actual position r _n, has a size corresponding to the amplitude information value An, and is at least the actual position r _n.
The position defined by the curve defined by the three actual positions r _{n + 1} and r _{n-1 in} the vicinity of this can be corrected in the direction of the perpendicular drawn from the actual position r _n . By doing so, a more accurate estimated surface position R _n can be obtained.

In the present invention, the estimated surface position R _n calculated in the calculating step is added to the size corresponding to the amplitude information value An and the offset amount D with respect to the stylus axis of the contact portion of the stylus. Is desirable. If the contact portion of the stylus is spherical, the offset amount D is given by its radius or the like. These are to add the distance of the actual contact position to the stylus axis position.

In the present invention, first, the scanning of the surface to be measured is completed, and during that period, all the required amplitude information values An for the surface and the actual positions r _n corresponding thereto are sequentially stored. , The information value group A ₀ stored after this
It is desirable to obtain to A _m and the estimated surface position group R ₀ to R _m from the actual position group r ₀ ~r _m corresponding thereto by performing the calculation. The amplitude information value An and the actual position r _n corresponding to the amplitude information value An may be sequentially stored by appropriately using the external computer system described above. Thus, information value A ₀ to A _m, a scanning step of detecting the actual position r ₀ ~r _m, estimated surface position group R ₀ to R _m
Since the calculation process for calculating the above can be sequentially performed separately, the control can be simplified as compared with the case of performing them in parallel, and since the mutual operation timings need not be considered, the operations in each can be adjusted to be the fastest.

In the present invention, the contact detection probe further comprises second vibrating means for resonating the stylus at a frequency f2 in the axial crossing direction, and in the scanning step, the second vibrating means is used. and that vibration is latched amplitude information value an of the detection signal output from the detecting circuit when it is in a predetermined phase, and controls the amplitude information value an of the latch as compared to the reference information value a _s can do. By doing so, the present invention can be realized by the tapping method described above.

At this time, the vibrating direction of the stylus by the second vibrating means is substantially orthogonal to the axial direction of the stylus and substantially orthogonal to the moving direction of the support in the scanning step. It is desirable to have
By doing so, tapping can be applied to the measurement surface of the object to be measured in a direction substantially at right angles.

In the present invention, the support has a posture operation means for rotating and inclining the contact detection probe in an arbitrary posture, and operates the posture of the contact detection probe according to the shape of the object to be measured. You may Thereby, the measurement surface of the object to be measured and the axis of the contact detection probe can be parallel to each other, and even when the measurement surface of the object to be measured is inclined, the measurement according to the present invention can be easily performed. it can.

At this time, the posture operation means is operated so that the vibration direction of the stylus by the second vibrating means is the normal direction of the surface of the object to be measured with which the contact portion contacts. Is desirable. Thus, even if the measurement surface of the object to be measured is inclined, more accurate measurement can be performed by tapping in the normal direction.

Information on the measurement surface of the object to be measured is required for operating the attitude of the contact detection probe. This information may be obtained, for example, by measuring the position of the measurement surface of the object to be measured at a plurality of positions prior to the measurement according to the present invention, or by designing the object data such as CAD data. You may use it.

In the present invention, it is desirable that the vibration of the stylus by the second vibrating means be linear. By doing so, an appropriate tapping operation can be realized in the present invention.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. In the following description, with respect to the same or similar parts as the parts or members already described,
The same reference numerals are given to omit or simplify the description. 1 and 2 show an inner and outer surface measuring device incorporating a surface shape measuring method according to a first embodiment of the present invention.

The inside / outside surface measuring apparatus 1 comprises a measuring device main body 2, a controller 3, a drive circuit 4, a detection circuit 5 and a personal computer 6. Drive circuit 4
Is for vibrating the touch signal probe 100 in the axial direction of the stylus and in the direction orthogonal to the axis,
The detection circuit 5 is a part that processes an electric signal from the detection means provided on the stylus and outputs the electric signal to the controller 3. In addition, the personal computer 6 outputs a control signal to the controller 3 to control the operation of the measuring instrument main body 2, and at the same time, the detection circuit 5 and the control means 31 of the controller 3.
The roundness and the like of the work W are evaluated by performing the arithmetic processing of the information from.

The measuring device main body 2 measures the surface shape of the work W by installing the work W, and the X on which the work W is installed.
A YZ table 21, a column 22 standing upright at the end of the XYZ table 21, a support 23 provided slidably in the extending direction of the column 22, and a touch signal supported by the support 23. And a probe 100. The XYZ table 21 is not shown in FIG. 1, but
In order to install the work W in the specified position,
The X-axis adjusting mechanism and the Y-axis adjusting mechanism that move along the surface of the YZ table 21, and the work W are transferred to the XYZ table 21.
And a Z-axis adjusting mechanism for moving the Z-axis in the direction normal to the surface. Then, after the work W is installed on the XYZ table 21, these axis adjusting mechanisms are operated to perform accurate position adjustment of the work.

The support 23 is not shown in FIG.
An X-axis drive mechanism and a Y-axis drive mechanism for moving the touch signal probe 100 along the surface of the XYZ table 21,
A Z-axis drive mechanism that moves the support body 23 up and down along the column 22 is provided, and the operation of these axis drive mechanisms is controlled by the controller 3 described later. The controller 3
The part that controls the operation of the support body 23 includes a control means 31 and an avoidance means 32.

The control means 31 controls the operation of the support body 23 of the measuring instrument main body 2 based on a command from the personal computer 6. The control means 31 is the support 23
The command speed vector V _n for the moving operation is sent to the axis drive mechanism of the
Perform a move based on V _n . Reference information value A _s is sent from the personal computer 6, such as during start operation to the control unit 31. Control means 31, during the movement of the support member 23, monitors the amplitude information values An of the detection circuit 5, the command speed vector V _n as the amplitude information value An approaches the reference information value A _s
Is set to control the movement of the support body 23. When the detection signal from the detection circuit 5 cannot maintain a predetermined value, the avoiding means 32 suspends the operation control by the control means 31, and moves in a direction opposite to the moving direction of the touch signal probe 100 by the control means 31 until then. , A part for outputting a control signal for moving the support 23. The avoidance means 32 causes the touch signal probe 100 to move to the work W.
With the contactless state, damage due to excessive contact force is prevented.

As shown in FIG. 2, the touch signal probe 1
00 is a stylus holder 101, a stylus 102,
The contact section 102A, the counter balance 102B, the vibrating means 103A, and the detecting means 103B are provided. Then, between the support body 23 and the stylus holder 101 supported by the support body 23, the second vibrating means 110 for vibrating the stylus 102 in the direction orthogonal to the axis of the stylus 102 is provided. It should be noted that the stylus 102 can be moved in any direction within a plane orthogonal to the axis of the stylus 102.
The second vibrating means 110 vibrates the X-axis vibrating elements 110X and Y that vibrate in directions orthogonal to each other.
The axial excitation element 110Y is provided, and the X-axis excitation element 110X and the Y-axis excitation element 110Y are arranged in series between the stylus holder 101 and the support body 23.

The drive circuit 4 is a portion for applying an electric signal to the vibrating means 103A and the second vibrating means 110 at a predetermined frequency, and is composed of a vibrating circuit 41 and a second vibrating circuit 42. The vibrating circuit 41 includes an oscillator that generates an electric signal that causes the vibrating means 103A to operate at a predetermined amplitude and a predetermined frequency, whereby the stylus 102 is provided.
Vibrates in the axial direction at frequency f1.

The second vibrating circuit 42 controls the above-mentioned X-axis vibrating element 110X and Y-axis vibrating element 110Y to have a predetermined amplitude,
It has an oscillator for generating an electric signal that operates at a predetermined frequency. It should be noted that this oscillator is based on the X-axis excitation element 1
Although the 10X and Y-axis excitation elements 110Y are operated in synchronization, the amplitudes of the electric signals of the excitation elements 110X and 110Y can be adjusted independently. Then, the stylus 102 vibrates in an arbitrary direction by applying electric signals having different amplitudes to the vibrating elements 110X and 110Y, and the stylus 102 synchronizes the vibrations of the vibrating elements 110X and 110Y. Stylus 1 with f2
It vibrates in an arbitrary direction orthogonal to the 02 axis.

The detection signal (amplitude information value An) from the detection circuit 5 is input to the personal computer 6.
A sampling signal of a predetermined cycle is output from the personal computer 6 to the detection circuit 5, and the detection circuit 5 outputs the amplitude information value An at the time when the sampling signal is sent. The current position (actual position r _n ) is input to the personal computer 6 from the control means 31. The same sampling signal as that for the above-mentioned detection circuit 5 is sent to the control means 31.
Outputs the actual position r _n corresponding to the amplitude information value An output from the detection circuit 5 described above to the personal computer 6. Further, the personal computer 6 stores a plurality of data sets of the amplitude information value An and the actual position r _n described above, and a calculation function for calculating an estimated surface position R _n by processing these is set by software. There is.

Next, the operation of the inner diameter measuring apparatus 1 according to the above-described first embodiment will be described when the shape of the inner peripheral surface W1 of the work W as shown in FIG. 3 is measured. (1) As shown in FIG. 3, the position coordinates of the center Ow of the inner circumference and the approximate radius Rw are acquired by performing three-point measurement in advance or utilizing CAD data. (2) Considering the amplitude of the second vibrating means 110 of the stylus 102, a circle S1 smaller than the radius Rw by Δr is set in the control means 31 as a basic movement locus of the contact portion 102A. Specifically, the contact portion 102A based on the angle θ from the measurement start point P0 and the radius Rw−Δr in FIG.
Control the operation of. The stylus 1 by the vibrating means 2
Since the amplitude of the vibration orthogonal to the 02 axis is extremely small, this Δr can be considered to be a value substantially equal to the radius of the contact portion 102A, but practically no problem.

(3) Second vibrating means 11 of the stylus 102
The electric signal of the second vibrating circuit 42 is set as a function of the angle θ so that the vibration due to 0 becomes the normal direction of the inner side surface of the inner peripheral surface W1, and the X-axis forming the second vibrating means 110. The vibrating element 110X and the Y-axis vibrating element 110Y are operated.
Specifically, the direction connecting the center point O of the circle S1 and the measurement start point P0 is set as the vibration direction of the X-axis exciting element 110X, and the axes of the stylus 102 of the X-axis exciting element 110X and the Y-axis exciting element 110Y are set. Assuming that the maximum force in the orthogonal direction is F and the frequency by the second excitation circuit is f2, the X-axis excitation element 110
Force Fx in the X-axis direction due to X and Y-axis excitation element 110
The force Fy in the Y-axis direction due to Y is set as the following function. Fx = F · sin (2π · f2 · t) · cos θ Fy = F · sin (2π · f2 · t) · sin θ As a result, the contact portion 102A moves the inner peripheral surface W1 at a predetermined cycle (1 / f2). Tapping. In addition, t in a formula shows time. (4) The stylus 102 is vibrated in the axial direction by the vibrating means 103A, and the inner peripheral surface W1 at the contact portion 102A.
While tapping the inner surface W by the control means 31.
Start scan of 1.

(5) During scanning, the control means 31 controls the detection circuit 5
The command velocity vector V _n is adjusted appropriately on the basis of the amplitude information value A _n to move the support 23 so that the touch signal probe 100 moves along the inner peripheral surface W1, and Amplitude information value A _n and control means 3
The actual position r _n from 1 is the information value group A ₀ ~ for each measurement point n = ₀ ~ m
It is accumulated in the personal computer 6 as A _m and the real position group r _{0 to} r _m . (6) When scanning is completed, the personal computer 6
Performs arithmetic processing from the stored amplitude information value group A ₀ were to A _m and the actual position group r ₀ ~r _m, calculates the estimated surface position R ₀ to R _m for each point of the inner peripheral surface W1 scanned. The details of these scanning and calculation procedures will be described below.

First, the movement (scanning operation) of the touch signal probe 100 during scanning will be described. In FIG. 4, the position of the touch signal probe 100 is r _n-1 , r _n ,
It is assumed that there is a transition to r _{n + 1} and r _{n + 2} . Each position r _n-1 , r _n , r
_{n + 1} and r _{n + 2} are position vectors r _n from the origin (0,0) of the coordinate system
It is expressed in the form = (x _n , y _n ). Arrows extending on both sides of each point in the figure represent vibration of the tapping operation. Here, a moving direction vector when moving from the point r _n to the next point r _{n + 1} (on the basis of this, the control means 31 sequentially sets the command velocity vector)
Is determined as follows.

At the nth measurement point, the amplitude information of the vibration obtained from the detection signal of the detecting means 5 is A _n, and the position information of the touch signal probe 100 at this time is the actual position r _n = (x _n , y
_n ). Similarly, at the (n + 1) th measurement point, the vibration amplitude information obtained from the detection signal of the detection means 5 is A _{n + 1,} and the position information of the touch signal probe 100 at this time is the actual position r _{n + 1} = _Let (x _{n + 1} , y _{n + 1} ). From these, point r _n to point
The moving direction vector to r _{n + 1} is v _{n + 1} = (x _{n + 1} -x _n , y _{n + 1} -y _n ) =
(v _{x n + 1} , v _{y n + 1} ). Similarly, v _n = (x _n -x _n-1 , y _n -y _{n- 1} ) = (v _xn , v _yn ) for the _immediately preceding measurement point. Therefore, if the moving direction vector has a constant size, it becomes as follows.

[0042]

[Equation 1]

The vector product of the moving direction vectors V _n and V _{n + 1} using the unit vector e _z in the Z-axis direction (axial direction of the stylus 102) is as follows.

[0044]

[Equation 2]

[0045]

[Equation 3]

If the sampling time interval is reduced, the change in direction θ is also reduced. Therefore, sin θ≈θ can be set. By modifying the equation (2) and the equation (3), the following can be set. it can.

[0047]

[Equation 4]

The movement of the touch signal probe 100, when the scanning of the inner circumferential surface W1, at a predetermined contact at any position, i.e. it is necessary to amplitude information value An is performed so as to keep the reference information value A _s due to the contact . That is, as shown in FIG. 5, at each point r _{n-1 to} r _{n + 2} , the amplitude information value An _{-1 at} each point
If there is a difference (A _n-1 -A _{s to} A _{n + 2} -A _s ) between ~ A _{n + 2} and the reference information value A _s, it is necessary to control them so that they disappear. Here, since P _n in equation (4) depends on A _n , θ =
In the vicinity of 0, it can be expressed as follows using the proportional constant k.

[0049]

[Equation 5]

From the above, the components of the moving direction vector
V _{x n + 1} and V _{y n + 1} can be calculated as follows.

[0051]

[Equation 6]

[0052]

[Equation 7]

Furthermore, by rearranging these equations (6) and (7), they can be finally expressed as follows.

[0054]

[Equation 8]

Thus, the nth point (position vector
The movement from V _n ) to the n + 1th point (position vector V _{n +1} ) can be determined using the amplitude information value An at that time. Normally, such processing is performed by digital arithmetic processing, so it is expected that discretization error will occur and affect the value R, but the value R should be corrected at any time so that it becomes a predetermined value. Can be solved with. As described above, the copying operation of the touch signal probe 100 is controlled, and at this time, the control unit 31 sets the support member 23 as a command velocity vector based on the moving direction vector V _{n + 1} obtained as described above.
Should be moved. Further, since the moving direction vector V _{n +1} has a shape along the inner peripheral surface W1, if the tapping vibration direction is corrected so as to be directed in a direction orthogonal to the moving direction vector V _{n + 1} , it is always The inner peripheral surface W1 can be tapped in the normal direction. Therefore, even if the shape of the object to be measured is not known, scanning is possible, and the measurement surface can always be reliably tapped in the normal direction.

Next, during the scanning as described above, the amplitude information value An obtained by sampling at each measurement point and the actual position
r _n (stored amplitude information value group A ₀ to A _m and the actual position group r ₀ ~r _m)
The process of calculating the estimated surface position R _n (R _{0 to} R _m ) of the inner peripheral surface W1 will be described.

In FIG. 6, the touch signal probe 100 is shown.
The output signal of has the following properties. In a state (A) in which the stylus 102 of the touch signal probe 100 is not in contact with the inner peripheral surface W1, the actual position r _n of the touch signal probe 100 points to the axial position of the stylus 102, and this position is the contact portion at the tip. It coincides with the center position of 102A. The state where the contact portion 102A is in contact with the inner peripheral surface W1 (B)
Then, a contact force F ₁ as a reaction force from the inner peripheral surface W1 is slightly generated. In this state, the position of the inner peripheral surface W1 is the actual position r _n and the spherical radius D of the contact portion 102A (stylus 1
It can be calculated by the sum of the offset amount from the 02 axis line).
When the stylus 102 is further pressed against the inner peripheral surface W1, the contact force F ₂ increases, and the stylus 102 is bent (C). In this state, the axial position of the stylus 102 and the center position of the contact portion 102A are displaced, and the contact portion 10
The center position of 2A is the actual position r _{n that} can be read from the control means 31.
Will be in a different state. This amount of displacement is the pushing amount d _n , and accurate measurement cannot be performed unless this value is eliminated or kept constant at all times.

In FIG. 7, the contact portion 102A and the inner peripheral surface W1 are not in contact with each other in the state of FIG. 6 (A) described above,
The stylus 102 is in the resonance state of the vibration f1 at any position, and the stylus 102 obtained from the detection circuit 5 is present.
The vibration amplitude information value An is constant at the maximum value A ₀ . As shown in FIG. 6B, when the contact portion 102A comes into contact with the inner peripheral surface W1, the resonance state of the stylus 102 collapses, vibration is suppressed, and the amplitude information value An decreases. The amplitude decrease becomes more remarkable as the contact force from the inner peripheral surface W1 becomes stronger, that is, as the pushing amount becomes larger. The proportional relationship at this time can be expressed by the sensitivity gradient k _s .

[0059] From this relationship, if always controlled so that the amplitude information value An becomes the predetermined reference information value A _s, it is possible to secure precision by certain of the pressing amount d _n described above. Specifically, even if an attempt is made to maintain the amplitude information value An at a predetermined reference information value A _s , the movement of the stylus 102 is a predictive control, so a slight deviation like A _n near the reference information value A _s occurs. It is assumed that the From the above, the actual position described above
r _n, the amplitude information values An, from the relationship of the reference information value A _s, push-in amount
It is possible to calculate d _n , and further to calculate the estimated surface position R _n of the inner peripheral surface W1 in consideration of the spherical radius D of the contact portion 102A. The relation between the scalar | d _n | of the indentation amount and the amplitude information value A _n is as follows from the sensitivity gradient k _s and the maximum amplitude value A ₀ .

[0060]

[Equation 9]

Therefore, the scalar of the pushing amount | d _n | is as follows.

[0062]

[Equation 10]

Further, the scalar | R _n | of the estimated surface position is estimated in consideration of the spherical radius D of the contact portion 102A as follows.

[0064]

[Equation 11]

By performing the above processing for each measurement point, it is possible to estimate the contact position on all the surfaces to be measured. In the above description, the property of the touch signal probe 100 is the constant sensitivity gradient k _s corresponding to the displacement, but the property is not always constant. Therefore, it is possible to further improve the accuracy by adopting a characteristic expression or a characteristic table by a more practical function or the like. The procedure for estimating the scalar | R _n | of the estimated surface position has been described above, and then the estimation of the actual estimated surface position R _n in which the direction is also taken into consideration will be described.

[0066] When the scanning shown in FIG. 4 is completed, the amplitude information value group to the personal computer 6 A ₀ to A _m and the corresponding actual position group _{r 0 (x 0, y 0} ) ~r m (x m, y _m ) are accumulated. Estimated surface positions R _{0 to} R _{m of the} inner peripheral surface W1 are obtained from these accumulated data as follows. First, the case of obtaining the estimated surface position Rn, the actual position r _n-1 before and after with respect to the actual position r _n, r _{n + 1}
It was used, and the position vector R _'n states of the contact force is zero, which determines the direction to correct the position vector R _n of normal.

[0067] As shown in FIG. 8, the auxiliary line vector h _'n = r
_{If n + 1} -r _n-1 is set, the vector hn = ± (y _{n + 1} -y
_n-1 ,-(x _{n + 1} -x _n-1 )) exists. Incidentally, in the figure, since the auxiliary line vector h _'n are substantially parallel to the tangential direction of the corresponding position of the measurement surface, it can be seen that the vertical vector hn is the direction perpendicular to the corresponding position of the measurement surface. Among the directions, considering the direction of correction of the position vector R _'n, it is possible orientations of control corresponding to the amplitude information in the scan measuring selects one direction as determined. The selection method is not limited to this. For example, since it is normally known which side of the scanning direction the scanning surface is in, it is possible to select any one direction based on this. The unit vector i _{n in the} direction to be corrected is obtained from the vector thus selected.

[0068]

[Equation 12]

R ′ _n can be calculated from r _n by giving the direction of the above equation (12) to the above equation (11).

[0070]

[Equation 13]

Further, the contact portion 102A which is the offset amount
The estimated surface position R _n is estimated in consideration of the spherical radius D of

[0072]

[Equation 14]

An estimated shape of the measurement surface (inner peripheral surface W1) is obtained from the set of R _n (R _{0 to} R _m ) obtained as described above.
In the above procedure, since the information of the measurement points before and after is used, the measurement surface positions (R ₀ , R _m ) at the end points (0th and mth) cannot be obtained. For example, the effective range may be expanded by expanding the end position.

According to the first embodiment as described above, after the stylus 102 is brought into contact with the surface of the object to be measured, the amplitude information value An and the actual position rn of each point are collected by scanning the surface, and From this, the estimated surface position Rn of each point can be calculated. At this time, the stylus controls the distance from the surface so that the amplitude information value An at each point becomes the reference information value As.
The amplitude information value An does not stay at each point until it converges to the reference information value As, and thus it does not take a convergence time as in the past.
On the other hand, for the estimated surface position Rn of each point, the actual position rn
It can be derived in a form corrected by An, and an accurate value can be obtained even if the stylus does not reach the position of the amplitude information value An = reference information value As.

Command speed vector for movement during scanning
V _{n + 1,} the difference in proportional constant k of the scalar vector product between the value V _n and the V _{n + 1} immediately before and the amplitude information values An and the reference information value A _s
Since to be determined by the multiplied value equivalent, it is possible to perform control of moving the stylus so that the amplitude information value An of the aforementioned approaches the reference information value A _s easily and appropriately.

[0076] During the operation, the estimated surface position R _n is, after determining the following actual position r _{n + 1} with respect to the actual position r _n, the start point of the actual position r _n, corresponding to said amplitude information value An With this size, the position is corrected in the direction orthogonal to the straight line connecting the next actual position r _{n + 1} and the previous actual position r _n-1. The estimated surface position R _n can be obtained.

At the time of calculation, the estimated surface position R _n is the amplitude information value.
The contact part 1 of the stylus 102 has a size corresponding to An.
By adding the offset amount D of 02A to the stylus axis, the distance of the actual contact position can be added to the stylus axis position, and accurate position measurement can be performed.

Regarding the processing of scanning and calculation, first, the scanning of the surface to be measured is completed, during which all necessary amplitude information values An of the surface and the corresponding actual position r _n are sequentially calculated. stored advance, the estimated surface position group R ₀ to R _m by performing the calculation from the following and stored information value group a ₀ had been to a _m and the actual position group r ₀ ~r _m corresponding thereto since the obtained manner, information value a ₀ to a _m, since the scanning process for detecting an actual position r ₀ ~r _m, performed separately in sequence and an arithmetic step of calculating an estimated surface position group R ₀ to R _m, The control can be simplified as compared with the case of performing them in parallel, and since it is not necessary to consider mutual operation timings, the operation in each can be adjusted to be the fastest.

Further, in this embodiment, the stylus 102 is used.
It is possible to adopt a tapping method by resonating at a frequency f2 in the axis crossing direction, and at the time of scanning, detection output from the detection circuit 5 when tapping vibration (frequency f2) is in a predetermined phase. latches amplitude information values an of the signal, the reference information value amplitude information value an of the latch a _s
Since the control is performed in comparison with, it is possible to realize accurate control.

At this time, the direction of the tapping vibration (frequency f2) in the stylus 102 is the stylus 10.
It is assumed that the vibration is substantially orthogonal to the axial direction of 2 and is substantially perpendicular to the moving direction of the support body 23 in the scanning step (direction of the measurement surface, scanning direction), and this vibration is linear. Appropriate tapping operation can be realized.

Next, a second embodiment of the present invention will be described. This embodiment is the same as the above-described first embodiment and device configuration,
The scanning procedure and the like are the same, but the calculation procedure of the estimated surface position R _n , which is the final stage of the calculation procedure, is different. Therefore, only the procedure for calculating the estimated surface position R _n , which is a different part, will be described, and description of the other common parts will be omitted. FIG. 9 shows a procedure for calculating the estimated surface position R _n of this embodiment. In the first embodiment 'has been set to _{n = r n + 1 -r n} -1, in this embodiment the auxiliary line vector h' auxiliary line vector h is set as _{n = r n -r n-1} . Subsequent calculations may be the same as in the first embodiment.

According to the second embodiment, the next actual position r _{n + 1} is not required as in the first embodiment, so that the detected data can be immediately processed. That is, when the detection data (amplitude information value An and the actual position r _n ) for all the measurement points are stored in advance and the estimated surface position R _n is collectively calculated later as in the first embodiment. , The next real position r _{n + 1} is easily obtained. However, if the estimated surface position R _n is calculated each time measurement is performed without accumulating the detection data, the next actual position r _{n + 1} cannot be obtained until the next measurement point is moved to. However, by using the calculation method as in the present embodiment, it is possible to surely perform the calculation processing even when the processing that does not accumulate the detection data is performed.

Next, a third embodiment of the present invention will be described. This embodiment is the same as the above-described first embodiment and device configuration,
The scanning procedure and the like are the same, but the calculation procedure of the estimated surface position R _n , which is the final stage of the calculation procedure, is different. Therefore, only the procedure for calculating the estimated surface position R _n , which is a different part, will be described, and description of the other common parts will be omitted. FIG. 10 shows a procedure for calculating the estimated surface position R _n of this embodiment. In the first embodiment 'Set _{n = r n + 1 -r n} -1, wherein in the second embodiment the auxiliary line vector h' auxiliary line vector h _n = r _n -r
_The calculation was performed by setting _n-1 and deriving a vertical vector h _n from each. In contrast, in the present embodiment, a plurality of measurement points in the vicinity of _{r n (r n-1,} r n, r n + 1, r n + 2 , etc.) is selected, an approximate curve Cn based on the points Set the actual position on this approximate curve C _n
r _n to a perpendicular line is drawn from the actual position r _n to a point nearest to the perpendicular line perpendicular vector h _n. Subsequent calculations may be the same as in the first embodiment.

According to the third embodiment, a larger number of measurement points (r _{n -1} , r _n , r _{n + 1} , r than those of the first embodiment are used.
_{n + 2} etc.) can be used to derive the vertical vector h _n ,
The measurement accuracy can be further improved. In particular, the first
Similar to the embodiment, when the scanning data is previously stored to store the inspection data and the calculation processing is collectively performed later, the data of a plurality of measurement points can be easily used, so that the accuracy can be easily increased. .

Next, a fourth embodiment of the present invention will be described. As shown in FIG. 11, the device configuration of this embodiment is almost the same as that of the first embodiment, but the support 23 has a posture operation means 24 for rotating and tilting the touch signal probe 100 in an arbitrary posture. The controller 3 has a posture control means 33, which is different in that the posture of the touch signal probe 100 is operated according to the inclination of the inner peripheral surface W1 of the workpiece W.

In actual measurement, it is necessary to manipulate the attitude of the touch signal probe 100 before scanning the inner peripheral surface W1 of the work W, and information about the inclination of the inner peripheral surface W1 of the work W is required. . For this, the position of the inner peripheral surface W1 of the work W is measured at a plurality of positions in advance, or the design data (CAD data) of the work W is used to determine the shape of the inner peripheral surface W1. You can leave it. In scanning the inner peripheral surface W1 of the work W, the relative positional relationship between the stylus 102 and the inner peripheral surface W1 is set to be the same as that in the first embodiment, but in the present embodiment, the inner peripheral surface W1 is tilted. Therefore, in addition to the X-axis drive mechanism and the Y-axis drive mechanism of the support member 23, the Z-axis drive mechanism is also controlled by the control means 31 to perform scanning.

In this embodiment, the rest of the device configuration is the same as that of the first embodiment, so the explanation is omitted here. Since the relative positional relationship between the stylus 102 and the inner peripheral surface W1 is the same as in the first embodiment, the calculation method of the estimated surface position R _n according to the scanning method in the first embodiment and the second and third embodiments will be described. Can be applied. In the present embodiment, since the posture operation means 24 and the posture control means 33 are provided, by obtaining the inclination information of the inner peripheral surface W1 in advance, tapping is always performed in the normal direction of the inner peripheral surface W1 by the contact portion 102A. It can be carried out.

The present invention is not limited to the above-mentioned embodiments, but includes the following modifications. The surface shape measuring method according to each of the above-described embodiments has been used to measure the inner peripheral surface W1 of the cylindrical work W, but the object to be measured is not limited to this. That is, the present invention may be used to continuously measure an outer peripheral surface of a cylindrical work W or a work having another complicated three-dimensional shape.

Further, in each of the above-mentioned embodiments, the vibrating means and the second vibrating means are composed of the piezoelectric elements 103A and 110, but the invention is not limited to this, and the vibrating means and the second vibrating means may be constituted by other structures. Means may be configured. In short, another structure may be adopted as long as it is a vibrating unit and a second vibrating unit that can vibrate the stylus in the axial direction and the direction orthogonal to the axis at a predetermined frequency.

Further, in each of the above embodiments, the touch signal probe is moved to measure the work, but the XYZ table on which the work is placed may be moved to perform the measurement. Further, the posture operation means is not limited to the one provided on the support, and the posture of the work may be operated by providing the posture operation means on the work placement surface of the XYZ table.
In addition, the specific structure, shape, and the like when implementing the present invention may be other structures and the like as long as the object of the present invention can be achieved.

Furthermore, the specific form of the contact detection probe,
In particular, the shape of the stylus tip may be selected appropriately,
In the case of the spherical contact portion 102A as in the first embodiment, its radius may be the offset amount D, and for other shapes, the offset amount from the reference axis line to the contact position may be considered. Further, although the probe that performs the tapping operation is used in each of the above-described embodiments, the present invention can be applied to the measurement of only the scanning operation that does not perform the tapping operation. In this case, the second vibrating means and the like of each of the above embodiments may be omitted as appropriate.

[0092]

As described above, according to the surface shape measuring method of the present invention, the estimated surface position can be calculated by processing the detection data instead of stabilizing the probe at each measurement point. It is possible to avoid the influence of the convergence time at each contact point of the measured object in the contact detection, and to improve the work efficiency while maintaining the high measurement accuracy.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an overall configuration of a first embodiment of the present invention.

FIG. 2 is a block diagram showing a main part of the first embodiment.

FIG. 3 is a schematic plan view showing a measurement state of the first embodiment.

FIG. 4 is a schematic plan view showing a scanning procedure of the first embodiment.

FIG. 5 is a graph showing changes in a detection signal in scanning in the first embodiment.

FIG. 6 is a schematic elevational view showing a contact state of the stylus tip of the first embodiment.

FIG. 7 is a schematic diagram showing a change in a detection signal according to a contact state of the stylus tip according to the first embodiment.

FIG. 8 is a schematic plan view showing a calculation procedure of the first embodiment.

FIG. 9 is a schematic plan view showing a calculation procedure according to the second embodiment of the present invention.

FIG. 10 is a schematic plan view showing a calculation procedure according to the third embodiment of the present invention.

FIG. 11 is a block diagram showing a main part of a fourth embodiment of the present invention.

FIG. 12 is a perspective view showing a stylus portion of a conventional touch signal probe.

[Explanation of symbols]

1 inner / outer surface measuring device 5 detecting means 6 personal computer 23 support 24 attitude manipulating means 31 controlling means 33 attitude controlling means 100 touch signal probe 101 stylus holder 102 stylus 102A contact part 103A vibrating means 103B detecting means 110 second vibrating means A _n Amplitude information value A _{0 to} A _m Amplitude information value group A _s Reference information value D Offset amount radius d _n Indentation amount R _n Estimated surface position R _{0 to} R _m Estimated surface position group r _n Actual position r ₀ to r _m Real position group W Workpiece W1 to be measured W1 inner surface

Continuation of front page (56) Reference JP-A-8-201010 (JP, A) JP-A-8-247743 (JP, A) JP-A-7-243846 (JP, A) JP-A-9-264897 (JP , A) Tokuhei 9-503857 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01B 21 / 00-21 / 32

Claims (12)

(57) [Claims] 1. A stylus having a support body which moves in a three-dimensional space at a predetermined command velocity vector in response to a command from the outside, a stylus having a contact portion which is supported by the support body and contacts the object to be measured, and the stylus. A contact detection probe including a vibrating unit that resonates at a frequency f1 in the axial direction and a detecting unit that detects a change in the vibration of the stylus by the vibrating unit is used. A surface shape measuring method for measuring the surface shape of the object to be measured from the position of the support at the time of contact, wherein the contact detection probe is moved by the command of the command velocity vector to measure the object to be measured. Contacting the surface to be processed, the amplitude information value of the detection signal output from the detection circuit
While controlling the distance to the surface to be measured so that An is a predetermined reference information value A _s , the contact detection probe is moved along the surface to be measured, and the amplitude information value An and this the step of scanning the surface to be the measurement by slide into outputs a corresponding real position r _n, the actual position r _n corresponding thereto and the amplitude information values an, such that the amplitude information value an becomes constant A surface shape measuring method comprising a step of calculating an estimated surface position R _n which is estimated to be obtained when scanning. 2. The surface shape measuring method according to claim 1, wherein the commanded velocity vector in the scanning step.
V _{n + 1,} the difference in proportional constant k of the scalar vector product between the value V _n and the V _{n + 1} immediately before and the amplitude information values An and the reference information value A _s
A surface shape measuring method characterized by being determined by making it equivalent to a doubled value. 3. The surface shape measuring method according to claim 1, wherein the estimated surface position R _n calculated in the calculating step is the next actual position with respect to the actual position r _n .
After the r _{n + 1} is determined, the actual position r _n is set as a starting point, and the next actual position r _{n + 1} and the previous actual position r _n-1 with a magnitude corresponding to the amplitude information value An. A surface shape measuring method characterized in that the position is corrected in a direction orthogonal to a straight line connecting the two. 4. The surface shape measuring method according to claim 1, wherein the estimated surface position R _n calculated in the calculating step has the actual position r _n as a starting point, and the amplitude information value. A surface shape measuring method, which has a size corresponding to An and is corrected in a direction orthogonal to a straight line connecting the actual position r _n and the previous actual position r _n-1 . 5. The surface shape measuring method according to claim 1, wherein the estimated surface position R _n calculated in the calculating step has the actual position r _n as a starting point, and the amplitude information value. Size corresponding to An, at least the actual position
A surface characterized in that the curve is defined by the three points of r _n and the real positions r _{n + 1} and r _{n-1 in} the vicinity of the curve and is corrected in the direction of a perpendicular line drawn from the real position r _n. Shape measurement method. 6. The surface shape measuring method according to claim 3, wherein the estimated surface position R _n calculated in the calculating step has a magnitude corresponding to the amplitude information value An. In addition to the above, an offset amount D with respect to the stylus axis of the contact portion of the stylus is further added to the surface shape measuring method. 7. The surface shape measuring method according to claim 1, wherein the scanning of the surface to be measured is completed first, and all the necessary amplitude information values for the surface are obtained during that period. an and this advance sequentially stores the actual position r _n corresponding information value group has been stored after the a ₀ to a _m
And a real position group r _{0 to} r _m corresponding thereto to obtain the estimated surface position group R _{0 to} R _m by performing the calculation. 8. The surface shape measuring method according to claim 1, wherein the contact detection probe further comprises second vibrating means for resonating the stylus at a frequency f2 in an axial crossing direction. In the scanning step, the amplitude information value An of the detection signal output from the detection circuit is latched when the vibration by the second vibrating means is in a predetermined phase, and the latched amplitude information value surface shape measuring method, wherein a an performing control as compared to the reference information value a _s. 9. The surface shape measuring method according to claim 8, wherein the vibration direction of the stylus by the second vibrating means is substantially orthogonal to the axial direction of the stylus, and in the scanning step. A surface shape measuring method characterized by being substantially orthogonal to the moving direction of the support. 10. The surface shape measuring method according to claim 1, wherein the support has a posture operation means for rotating and tilting the contact detection probe in an arbitrary posture, and A surface shape measuring method characterized by operating the attitude of the contact detection probe according to the shape of the object to be measured. 11. The surface shape measuring method according to claim 10, wherein a vibration direction of the stylus by the second vibrating means is a normal line direction of a surface of the object to be measured with which the contact portion comes into contact. A surface shape measuring method, characterized in that the posture operating means is operated so that 12. The surface shape measuring method according to claim 8, wherein vibration of the stylus by the second vibrating means is linear. .