JP2001099639A - Measurement method for surface shape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement method for surface shape capable of avoiding the effect of converging time of every contact point of object to be measured in vibrator type contact detection, maintaining high measurement accuracy and raising work efficiency. SOLUTION: A measurement method for surface shape includes a process that a touch signal probe 100 is moved to contact on the surface to be measured by the command of a command velocity vector Vn, a process that the distance to the surface to be measured is controlled so that the amplitude information value An of the detection signal outputted from a detection circuit 5 becomes a specified reference information value As, the touch signal probe 100 is moved along the surface to be measured and the surface to be measured is scanned so as to output the amplitude information value An and its corresponding actual position rn, and a process that an estimated surface position Rn estimated to be obtained when it is scanned so that the amplitude information value An and its corresponding actual position rn become constant is operated.

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. The improvement of measurement efficiency and accuracy.

[0002]

2. Description of the Related Art A height gauge (one-dimensional measuring device), a three-dimensional measuring device, and a contour measuring device are known as measuring devices 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 measurement device main body and the device under test. These probes are classified into a non-contact probe and a contact probe, or a continuous measurement probe and a contact detection probe (touch trigger probe). An ultrasonic touch signal probe disclosed in JP-A-6-221806 is known as a contact detection probe for a coordinate measuring machine.

[0003] 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, a stylus holder for supporting the stylus,
It is configured to include a vibrating means for causing the stylus to resonate 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 face of the object under measurement while the stylus is vibrated by the vibration means, the state of vibration of the stylus changes due to the contact force. By detecting with the detecting means, the end face position of the measured object can be detected.

In some cases, such an ultrasonic touch signal probe is used to measure the diameter of a small hole or the like. In order to enable measurement of a small hole or the like, a small ultrasonic touch signal probe is used. A 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 vibration unit 103A, and a detection unit 103B. At the tip of the stylus 102, there is provided a contact portion 102A that comes into contact with the object to be measured.
Is provided, and the center position in the axial direction of the stylus 102 is set as the position of the center of gravity. When the stylus 102 is vibrated in the axial direction, the node of the vibration is at the position of the center of gravity.

[0005] Such a touch signal probe 100 includes:
In order to enable small hole measurement, the stylus 102 is formed of a thin rod-shaped member, and the contact portion 102A is formed of a small-diameter spherical body in accordance with 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 102 is supported at two places with the center of gravity of the stylus 102 interposed therebetween.

[0006] Vibration means 103A and detection means 103B
Is formed by dividing a piezoelectric element 103, which is arranged so as to extend over two supporting portions of the stylus holder 101, into two parts. Then, the stylus 1 is moved by the vibration means 103A.
02 resonates along the axial direction, a node of vibration occurs at the position of the center of gravity of the stylus 102 and the stylus holder 10
The supporting portion of one stylus 102 is located at such a position as to sandwich the node of the vibration.

According to such a touch signal probe 100, since the stylus holder 101 supports the stylus 102 at two places with the node of vibration interposed therebetween, 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) in which the surface of the object to be measured is brought into contact with the surface by vibrating operation has been developed (Japanese Patent Application No. 11-96377). In this method, for example, the above-mentioned stylus holder 101 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 in a direction in which the stylus 102 approaches and separates from the object to be measured. It is to let. According to such a tapping method, even if the stylus 102 is moved along the surface of the object to be measured and the surface shape is continuously measured, the contact portion 10
Since the stylus 102 has a small rigidity, the dragging (adhesion phenomenon) of the object can be avoided by the 2A being close to and separated from the object to be measured. Therefore, there is an effect that the working efficiency can be improved by continuous measurement while maintaining high accuracy.

[0009]

However, in the above-described ultrasonic vibration type touch signal probe, the timing at which a trigger for contact detection is output 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 starts to be suppressed when the contact starts. Further, the stylus is further suppressed by virtue of contact between the contact portion and the surface of the device under test with a certain amount of pressure contact force. At this time, since there is a correlation between the pressed state against the surface of the object to be measured and the vibration suppression state, the output signal of the detection means is monitored, and if it is determined that the vibration suppression has reached a predetermined level, the vibration is suppressed. The amount by which the stylus is pushed into the measurement object is constant, and accurate position detection is possible.

However, the measurement of the position of one point on the surface of the object to be measured requires a repetitive operation such as detecting and detecting the stylus in close proximity to the stylus until the vibration state of the stylus converges to a predetermined state at that position. is there. In particular, when a large number of points are inspected, such as in the continuous measurement of the surface of an object to be measured, the total work time may be enormous. On the other hand, when measuring the position of each point on the object to be measured, if the vibration state of the stylus is not strictly converged at that position, but is converged within a predetermined range, the work time can be reduced. However, in this case, the measurement accuracy is naturally inferior.

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

[0012]

According to the present invention, in the conventional vibratory 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 attention was paid to the fact that the convergence time was caused by the complexity of finely moving the stylus toward and away. Then, instead of actually setting the stylus at the predetermined position, the information on the predetermined position that should have been settled conventionally is calculated based on the information from the detecting means obtained in the vicinity and the position information of the stylus. It is intended to accurately and efficiently measure the position of the surface of the measurement object.

More specifically, a support that moves in a three-dimensional space at a predetermined command velocity vector in response to an external command,
A stylus supported by the support and having a contact portion that comes into contact with the object to be measured; vibrating means for resonating the stylus at a frequency f1 in the axial direction; and detecting a change in vibration of the stylus caused by the vibrating means. Using a contact detection probe equipped with a detection means, a surface shape measuring method for measuring the surface shape of the object to be measured from the position of the support when the contact portion contacts the surface of the object to be measured, In accordance with the command of the command speed vector, the step of moving the contact detection probe to make contact with the surface to be measured of the device under test, the amplitude information value An of the detection signal output from the detection circuit is a predetermined reference information while controlling the distance between the measuring surface to be such that the value a _s, the contact detection probe is moved along the surface to be the measurement, the amplitude information values
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 characterized in that it comprises a step of calculating an estimated surface position R _n which is estimated to be obtained when scanned so as to.

As the contact detection probe, the aforementioned ultrasonic vibration type touch signal probe or the like can be used. The stylus may have a structure that is supported via a stylus holder connected to the support. An existing driving element such as a piezoelectric element can be used as appropriate as the vibration means.
A power supply and a driving circuit may be externally connected to operate the vibration means. The detecting means can also be constituted by a piezoelectric element, and an existing structure such as a structure integrated with the vibrating means can be appropriately adopted. The driving of the support may depend on an existing CMM, 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. Collection of amplitude information value An and actual position r _n in scanning process and estimated surface position
The calculation of R _n may be performed in parallel, or each step may be sequentially performed as described later. To perform in parallel means to calculate the estimated surface position R _n-2 from the actual position r _n-2 from the amplitude information value An _-2 and the actual position r _n-2 several steps before using the external computer while detecting the r _n position. And so on.

[0015] In such a configuration, after contacting the stylus on the surface of the object to be measured, the amplitude information values An of each point by scanning the surface, the actual position r _n are collected, estimated from these points 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 command speed vector V _{n + 1} in the scanning step is obtained by comparing the immediately preceding value V _n with the value 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 Starting point,
The size corresponding to the amplitude information value An, the next actual position
The position can be a position corrected in a direction orthogonal to a straight line connecting r _{n + 1} and the previous real position r _{n -1} . Thus, it is possible to obtain an accurate estimation surface position R _n by a simple operation.

The estimated surface position R _n calculated in the calculating step starts from the real position r _n , and has a size corresponding to the amplitude information value An, and has a size corresponding to the real position r _n and one. The position can be a position corrected in a direction orthogonal to a straight line connecting the previous actual position r _n-1 . In this way, the next real position r _{n + 1} is not required, and thus the detection data can be immediately processed.

Furthermore, the estimated surface position R _n which is calculated in the step of the operation, the actual position r _n a start point, a size corresponding to the amplitude information values An, at least the actual position r _n
And a position corrected in the direction of a perpendicular drawn down from the real position r _n to a curve defined by three points of the real positions r _{n + 1} and r _{n-1 in} the vicinity thereof. Thus, it is possible to obtain a more accurate estimation surface position R _n.

In the present invention, the estimated surface position R _n calculated in the calculating step is determined by adding an offset amount D of the contact portion of the stylus to the stylus axis to a size corresponding to the amplitude information value An. Is desirable. For example, if the contact portion of the stylus is spherical, the offset amount D is given by its radius or the like. These are to take into account the distance of the actual contact position with respect to the stylus axis position.

In the present invention, the scanning of the surface to be measured is completed first, and all the necessary amplitude information values An and the corresponding actual positions r _n of the surface are sequentially stored during the scanning. , The information value group A ₀ stored thereafter
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
Can be separately and sequentially performed, the control can be simplified as compared with the case of performing the operations in parallel, and the operation in each can be adjusted to be the fastest since there is no need to consider mutual operation timing.

In the present invention, the contact detection probe further includes second vibrating means for causing the stylus to resonate at a frequency f2 in a direction crossing the axis, and in the scanning step, the second vibrating means uses the second vibrating means. 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. In this way, the present invention can be realized in the tapping method described above.

At this time, the direction of vibration of the stylus by the second vibrating means is substantially perpendicular to the axial direction of the stylus and substantially perpendicular to the direction of movement of the support in the scanning step. Is desirable.
With this configuration, tapping can be always applied in a direction substantially perpendicular to the measurement surface of the object to be measured.

In the present invention, the support has posture operation means for rotating and tilting the contact detection probe to an arbitrary posture, and operates the posture of the contact detection probe according to the shape of the object to be measured. It may be. This makes it possible to make the measurement surface of the object to be measured and the axis of the contact detection probe parallel, and to easily perform the measurement based on the present invention even when the measurement surface of the object to be measured is inclined. it can.

At this time, the attitude manipulating means is operated so that the direction of vibration of the stylus by the second vibrating means is a normal direction of a surface of the object to be contacted with the contact portion. It is desirable. Thereby, even when the measurement surface of the object to be measured is inclined, more accurate measurement can be performed by tapping in the normal direction.

When the attitude of the contact detection probe is operated, information on the measurement surface of the object to be measured is required. This information may be obtained by, for example, prior to the measurement according to the present invention, measuring the position of a plurality of points on the measurement surface of the measurement object to determine the shape of the measurement surface, or extracting design data of the measurement object, for example, CAD data. May be used.

In the present invention, it is desirable that the vibration of the stylus by the second vibrating means is linear. This makes it possible to implement an appropriate tapping operation in the present invention.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In the following description, for the same or similar parts as the already described parts or members,
The same reference numerals are given and the description is omitted or simplified. FIGS. 1 and 2 show an inner and outer surface measuring apparatus incorporating a surface shape measuring method according to a first embodiment of the present invention.

The inner / outer surface measuring apparatus 1 includes 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 a direction perpendicular to the axis,
The detection circuit 5 is a portion that processes an electric signal from a detection unit provided on the stylus and outputs the processed signal to the controller 3. Further, the personal computer 6 outputs a control signal to the controller 3 to control the operation of the measuring instrument body 2, and controls the detection circuit 5 and the control means 31 of the controller 3.
, And the roundness of the work W is evaluated.

The measuring instrument body 2 is for measuring a surface shape by installing a work W.
An YZ table 21, a support 22 erected at the end of the XYZ table 21, a support 23 slidably provided in the direction in which the support 22 extends, and a touch signal supported by the support 23. And a probe 100. Although the XYZ table 21 is not shown in FIG.
In order to set the work W at a predetermined position, the work W
An X-axis adjustment mechanism and a Y-axis adjustment mechanism that move along the surface of the YZ table 21;
And a Z-axis adjustment mechanism for moving the surface in the normal direction. After the work W is set on the XYZ table 21, these shaft adjustment 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 for moving the support 23 up and down along the column 22; the operation of these axis drive mechanisms is controlled by a controller 3 described later. Controller 3
It is a part for controlling the operation of the support 23, and includes a control means 31 and an avoidance means 32.

The control means 31 controls the operation of the support 23 of the measuring device main body 2 based on a command from the personal computer 6. The control means 31 includes the support 23
Command feed speed vector V _n, the axial drive mechanism of the support member 23 the commanded velocity vector for the moving operation the axial drive mechanism
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, and the movement of the support 23 is controlled. When the detection signal from the detection circuit 5 cannot maintain the predetermined value, the avoidance unit 32 stops the operation control by the control unit 31 and moves the touch signal probe 100 in a direction opposite to the moving direction of the touch signal probe 100 by the control unit 31 until then. , A portion for outputting a control signal for moving the support 23. By this avoiding means 32, the touch signal probe 100 allows the work W
, So that 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,
A contact portion 102A, a counter balance 102B, a vibrating means 103A, and a detecting means 103B are provided. Further, between the support member 23 and the stylus holder 101 supported by the support member 23, a second vibration means 110 for vibrating the stylus 102 in a direction orthogonal to the axis of the stylus 102 is provided. Note that the stylus 102 may be moved in any direction on a plane orthogonal to the axis of the stylus 102.
In order to vibrate, the second vibrating means 110 includes X-axis vibrating elements 110X and Y vibrating in directions orthogonal to each other.
An X-axis excitation element 110X and a Y-axis excitation element 110Y are provided in series between the stylus holder 101 and the support 23.

The drive circuit 4 is a part for applying an electric signal to the vibration means 103A and the second vibration means 110 at a predetermined frequency, and comprises a vibration circuit 41 and a second vibration circuit 42. The vibrating circuit 41 includes a transmitter that generates an electric signal that causes the vibrating means 103A to operate at a predetermined amplitude and a predetermined frequency.
Vibrates in the axial direction at the frequency f1.

The second vibration circuit 42 converts the above-described X-axis vibration element 110X and Y-axis vibration element 110Y to a predetermined amplitude,
A transmitter is provided for generating an electrical signal that operates at a predetermined frequency. Note that this transmitter is an X-axis exciting element 1
The 10X and Y-axis excitation elements 110Y are operated synchronously, but the amplitudes of the electric signals of the respective excitation elements 110X and 110Y can be adjusted independently. The stylus 102 vibrates in an arbitrary direction by giving electric signals having different amplitudes to the respective vibrating elements 110X and 110Y. By synchronizing the vibrations of both vibrating elements 110X and 110Y, the stylus 102 Stylus 1 at f2
Vibrates in any 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 period is output from the personal computer 6 to the detection circuit 5, and the detection circuit 5 outputs an amplitude information value An at the time when the sampling signal is sent. Further, the current position (actual position r _n ) is input from the control means 31 to the personal computer 6. The same sampling signal as that for the detection circuit 5 described above is sent to the control means 31, and the control means 31
Outputs the actual position r _n corresponding to the amplitude information value An output from the detection circuit 5 to the personal computer 6. Further, in the personal computer 6, a plurality of data sets of the amplitude information value An and the actual position r _n described above are stored, and an arithmetic function for calculating these to obtain an estimated surface position R _n is set by software. I have.

Next, the operation of the inner diameter measuring device 1 according to the first embodiment described above will be described for the case where the shape of the inner peripheral surface W1 of the work W is measured as shown in FIG. (1) As shown in FIG. 3, the position coordinates of the center Ow of the inner circumference and the approximate radius Rw are obtained by performing three-point measurement in advance or using CAD data. (2) Considering the amplitude of the stylus 102 by the second vibration means 110, a circle S1 smaller than the radius Rw by Δr is set in the control means 31 as a basic motion trajectory of the contact portion 102A. Specifically, the contact portion 102A is determined based on the angle θ from the measurement start point P0 in FIG.
Operation control. In addition, stylus 1 by vibrating means 2
Since the amplitude of the vibration orthogonal to the axis 02 is extremely small, this Δr can be practically considered even if it is considered to be substantially equal to the radius of the contact portion 102A.

(3) Second vibrating means 11 of stylus 102
The electric signal of the second vibration circuit 42 is set as a function of the angle θ so that the vibration due to 0 is in the normal direction of the inner surface of the inner peripheral surface W1. The vibration element 110X and the Y-axis vibration element 110Y are operated.
Specifically, the direction connecting the center point O of the circle S1 and the measurement start point P0 is defined as the vibration direction of the X-axis vibration element 110X, and the direction of the stylus 102 of the X-axis vibration element 110X and the Y-axis vibration element 110Y. Assuming that the maximum force in the orthogonal direction is F and the frequency of the second vibration circuit is f2, the X-axis vibration element 110
X-axis force Fx by X and Y-axis vibration element 110
The force Fy in the Y-axis direction by Y is set as the following function. Fx = F · sin (2π · f2 · t) · cos θ Fy = F · sin (2π · f2 · t) · sinθ Accordingly, the contact portion 102A moves the inner peripheral surface W1 at a predetermined period (1 / f2). Tap. Note that t in the formula indicates time. (4) The stylus 102 is vibrated in the axial direction by the vibration means 103A, and the inner peripheral surface W1 is
While tapping the inner surface W by the control means 31.
Scan 1 starts.

(5) During scanning, the control means 31 controls the detection circuit 5
The amplitude information values A _n command based on the velocity vector V _n is suitably adjusted, as well as to move along the support member 23 is moved touch signal probe 100 inner peripheral surface W1, the detection circuit 5 from Amplitude information value _An and control means 3
The actual position r _n from 1 is the information value group A _{0 for} each measurement point n = ₀ to m
Yuku stored in the personal computer 6 as A _m and the actual position group r ₀ ~r _m. (6) When the 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. Hereinafter, the details of these scanning and calculation procedures will be described.

First, the movement of the touch signal probe 100 (scanning operation) during scanning will be described. In FIG. 4, the position of the touch signal probe 100 is r _n−1 , r _n ,
The transition is assumed to be 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
= (x _n , y _n ). Arrows extending on both sides of each point in the figure represent the vibration of the tapping operation. Here, the moving direction vector when moving from point r _n to r _{n + 1} of the next point (controlling means 31 based on this setting the command speed vector sequentially)
Is determined as follows.

[0041] In the n-th measurement point, the amplitude information of the vibration obtained from the detection signal of the detection means 5 and A _n, this time of the touch signal position information actual position r _n = (x _n probes 100, y
_n ). Similarly, at the (n + 1) th measurement point, the amplitude information of the vibration obtained from the detection signal of the detection means 5 is set to _{An + 1,} and the position information of the touch signal probe 100 at this time is set to the actual position rn _{+ 1} = (x _{n + 1} , y _{n + 1} ). From these, the point from the point r _n
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, when the moving direction vector has a constant size, the following is obtained.

[0042]

(Equation 1)

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

[0044]

(Equation 2)

[0045]

(Equation 3)

If the sampling time interval is reduced, the change θ in the direction is also reduced, so that sin θ ≒ θ can be obtained. The following equation is obtained from the modification of the equation (2) and the equation (3). 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
After that there is a difference between to A _{n + 2} and the reference information value _{A s (A n-1 -A} s ~A n + 2 -A s), it is necessary to control such that they disappear. Here, since the P _n of formula (4) which depends on the A _n, theta =
In the vicinity of 0, it can be expressed as follows using the proportionality 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 obtained as follows.

[0051]

(Equation 6)

[0052]

(Equation 7)

Further, when these equations (6) and (7) are arranged, they can be finally expressed as follows.

[0054]

(Equation 8)

As described above, the n-th point (position vector
Transfer from V _n) to (n + 1) -th point (position vector V _{n +1)} may be determined by using the amplitude information value An at that time. Normally, since such processing is performed by digital arithmetic processing, it is expected that a discretization error will occur and affect the value R. However, it is necessary to correct the value R to a predetermined size as needed. Can be solved. As described above, the copying operation of the touch signal probe 100 is controlled, and at this time, the control unit 31 outputs a command speed vector based on the movement 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 vibration direction of the tapping is corrected so as to be directed in a direction orthogonal to the moving direction vector V _{n +1} , The inner peripheral surface W1 can be hit in the normal direction. Therefore, scanning is possible even when the shape of the object to be measured is not known, 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 of the inner circumferential surface W1 (R ₀ ~R _m) from explained.

In FIG. 6, the touch signal probe 100
Has the following properties. In the state (A) where 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 indicates the axis position of the stylus 102, and this position is the contact portion at the tip. It matches the center position of 102A. The state where the contact portion 102A is in contact with the inner peripheral surface W1 (B)
It becomes a contact force F ₁ as a reaction force from the inner peripheral surface W1 occurs slightly. In this state, the position of the inner peripheral surface W1 is the actual position r _n and the spherical radius D (the stylus 1) of the contact portion 102A.
02 (offset from the axis 02).
When the stylus 102 is pressed against the inner peripheral surface W1 Further, the contact force F ₂ increases, and a bent state stylus 102 (C). In this state, the axial position of the stylus 102 deviates from the center position of the contact portion 102A, and the contact portion 10A
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. The shift amount is pressing depth d _n, can not be accurately measured unless whether to set always constant eliminate this value.

In FIG. 7, in the state of FIG. 6A described above, the contact portion 102A is not in contact with the inner peripheral surface W1,
At any position, the stylus 102 is in a resonance state of the vibration f1, and the stylus 102 obtained from the detection circuit 5
Oscillation amplitude information values of An are constant at the maximum value A _0. When the contact portion 102A comes into contact with the inner peripheral surface W1 as shown in FIG. 6B, the resonance state of the stylus 102 collapses, vibration is suppressed, and the amplitude information value An decreases. The decrease in amplitude becomes more remarkable as the contact force from the inner peripheral surface W1 becomes stronger, that is, as the pushing amount increases. Proportionality in this case 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 an attempt to maintain as amplitude information value An becomes the predetermined reference information value A _s, a little deviation as reference information value A _s neighborhood of A _n for the movement of the stylus 102 is predictive control Shall be in a state where 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
can be calculated d _n, the estimated surface position R _n of the inner circumferential surface W1 is can be calculated by further adding the radius D of the spherical contact portion 102A. The relationship between the scalar | d _n | of the pushing amount and the amplitude information value _An is as follows from the sensitivity gradient k _s and the maximum amplitude value A ₀ .

[0060]

(Equation 9)

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

[0062]

(Equation 10)

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

[0064]

[Equation 11]

If the above processing is performed for each measurement point, it is possible to estimate the contact positions of all the surfaces to be measured. Although in the above description and the constant sensitivity slope k _s corresponding to the displacement properties of the touch signal probe 100, not actually always constant. For this reason, the accuracy can be further improved by using a characteristic expression or a characteristic table using a function or the like that is more practical. The procedure for estimating the scalar | R _n | of the estimated surface position has been described above. Next, the estimation of the actual estimated surface position R _n in consideration of the direction 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 ) is accumulated. Estimated surface position R ₀ to R _m of the inner peripheral surface W1 from these stored data as follows is obtained. 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.

As shown in FIG. 8, the auxiliary line vector h ′ _n = r
_{If n + 1} -r _n-1 is set, the vector perpendicular to this is hn = ± (y _{n + 1} -y
_n-1 ,-(x _{n + 1} -x _n-1 )). 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 the measurement surface usually knows which side in the traveling direction of the scanning measurement, any one of the directions may be selected based on this. Thus obtaining a unit vector i _n the direction to correct the selected vector.

[0068]

(Equation 12)

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

[0070]

(Equation 13)

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

[0072]

[Equation 14]

The estimated shape of the measurement surface (inner surface W1) is obtained from the set of R _n (R _{0 to} R _m ) obtained as described above.
In the above-mentioned 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 increased by expanding the end position.

According to the above-described first embodiment, 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. , The estimated surface position Rn of each point can be calculated. At this time, the stylus is controlled in distance from the surface so that the amplitude information value An of 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 does not require a convergence time as in the related art.
On the other hand, the estimated surface position Rn of each point is represented by
It can be derived by correcting with An, and an accurate value can be obtained without the stylus reaching the position of the amplitude information value An = reference information value As.

During scanning, a command speed vector for movement
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 the size, the position was corrected in a direction orthogonal to the straight line connecting the next real position r _{n + 1} and the previous real position r _n-1 , so it is accurate with a simple calculation it is possible to obtain an estimated surface position R _n.

At the time of calculation, the estimated surface position R _n is an amplitude information value.
The contact part 1 of the stylus 102 with a size corresponding to An
By taking into account the offset amount D with respect to the stylus axis of 02A, the distance between the stylus axis position and the actual contact position can be taken into account, and accurate position measurement can be performed.

As for the scanning and calculation processing, the scanning for the surface to be measured is completed first, and all the necessary amplitude information values An for the surface and the corresponding actual positions r _n are sequentially stored in the meantime. 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 where the operations are performed in parallel, and since the mutual operation timing does not need to be considered, the operation in each can be adjusted to be the fastest.

Further, in this embodiment, the stylus 102
Is resonated at a frequency f2 in the cross-axis direction, so that a tapping method can be performed. In scanning, a detection output from the detection circuit 5 when the tapping vibration (frequency f2) is in a predetermined phase is obtained. 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 as compared with the control, accurate control can be realized.

At this time, the direction of the tapping vibration (frequency f2) in the stylus 102 is
2 is substantially perpendicular to the axial direction, and substantially perpendicular to the direction of movement (direction of the measuring surface, scanning direction) of the support 23 in the scanning step, and the 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 first embodiment described above and the device configuration,
Procedures, and the like of the scan is the same, the procedure for calculating the estimated surface position R _n is the final stage of the algorithm are different. Therefore, it describes only the procedure for calculating the estimated surface position R _n are different parts, the other common parts will be omitted. It is shown procedures for calculating the estimated surface position R _n of the present embodiment in FIG. 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, since the next real position r _{n + 1} is not required unlike the first embodiment, the detection data can be immediately processed. That is, as in the first embodiment, when the detection data (the amplitude information value An and the actual position r _n ) regarding all the measurement points are first accumulated, and the estimated surface position R _n is collectively calculated later. , The next real position r _{n + 1} is easily obtained. However, in the case _where the estimated surface position Rn is calculated each time measurement is performed at each measurement point without accumulating the detection data, the next actual position rn _{+ 1} cannot be obtained until the next measurement point is transferred. However, by using the calculation method as in the present embodiment, the calculation process can be reliably performed even when the process 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 first embodiment described above and the device configuration,
Procedures, and the like of the scan is the same, the procedure for calculating the estimated surface position R _n is the final stage of the algorithm are different. Therefore, it describes only the procedure for calculating the estimated surface position R _n are different parts, the other common parts will be omitted. Are shown procedures for calculating the estimated surface position R _n of the present embodiment in FIG. 10. In the first embodiment, the auxiliary line vector h ′ _n = r _{n + 1} −r _n−1 is set, and in the second embodiment, the auxiliary line vector h ′ _n = r _n −r
Set _n-1, were computed led to a vector perpendicular h _n from each. In contrast, in the present embodiment, a plurality of measurement points (r _n−1 , r _n , r _{n + 1} , r _{n + 2,} etc.) near r _n are selected, and an approximate curve Cn is formed based on each point. Set the actual position on this approximation 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, the number of measurement points (r _{n -1} , r _n , r _{n + 1} , r _{n) is} larger than in the first embodiment.
_{n + 2} ) can be used to derive a vertical vector h _n ,
Measurement accuracy can be further improved. In particular, the first
In the same manner as in the embodiment, when scanning is first performed to accumulate inspection data, and when arithmetic processing is collectively performed later, data at a plurality of measurement points can be easily used, so that high accuracy can be easily achieved. .

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 member 23 has a posture operation means 24 for rotating and tilting the touch signal probe 100 to an arbitrary posture. The controller 3 has a posture control means 33, which differs in that the posture of the touch signal probe 100 is operated in accordance with the inclination of the inner peripheral surface W1 of the work W.

In the actual measurement, it is necessary to operate the attitude of the touch signal probe 100 before scanning the inner peripheral surface W1 of the work W, and information on the inclination of the inner peripheral surface W1 of the work W is required. . For this, the position of a plurality of locations on the inner peripheral surface W1 of the work W is measured in advance, or the shape of the inner peripheral surface W1 is determined using design data (CAD data) of the work W. It is good. 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 the same as in the first embodiment. Therefore, in addition to the X-axis driving mechanism and the Y-axis driving mechanism of the support 23, the Z-axis driving mechanism is controlled by the control unit 31 to perform scanning.

In the present embodiment, the other configuration of the apparatus is the same as that of the first embodiment, and the description is omitted here. Since the relative positional relationship between the inner circumferential surface W1 and the stylus 102 is the same as in the first embodiment, the scanning method and the second embodiment of the first embodiment, the calculation procedure of the estimated surface position R _n according to the third embodiment Can be applied. In the present embodiment, since the attitude control means 24 and the attitude control means 33 are provided, by obtaining the inclination information of the inner peripheral surface W1 in advance, the 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-described embodiments, but includes the following modifications. The surface shape measuring method according to each of the embodiments has been used to measure the inner peripheral surface W1 of the cylindrical workpiece W, but the object to be measured is not limited to this. That is, the present invention may be used to continuously measure the outer peripheral surface of the cylindrical work W or another work having a complicated three-dimensional shape.

In each of the above embodiments, the vibrating means and the second vibrating means are constituted by the piezoelectric elements 103A and 110. However, the present invention is not limited to this, and the vibrating means and the second vibrating means may have other structures. Means may be constituted. In short, other configurations may be adopted as long as the vibration unit and the second vibration unit can vibrate the stylus at a predetermined frequency in the axial direction and the direction perpendicular to the axis.

Further, in each of the above embodiments, the work is measured by moving the touch signal probe. However, the measurement may be performed by moving the XYZ table on which the work is placed. Further, the attitude manipulating means is not limited to the one provided on the support, and the posture of the work may be operated by providing the posture manipulating means on the work mounting surface of the XYZ table.
In addition, specific structures, shapes, and the like at the time of carrying out the present invention may be other structures and the like as long as the object of the present invention can be achieved.

Further, the specific format of the contact detection probe is as follows:
In particular, the shape of the tip of the stylus may be appropriately selected,
In the case of the spherical contact portion 102A as in the first embodiment, the radius may be set as the offset amount D, and in other shapes, the offset amount from the reference axis to the contact position may be considered. In each of the above embodiments, the probe performs the tapping operation. However, the present invention can be used for measuring only the copying operation without performing the tapping operation. In this case, the second vibration means and the like in 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, instead of stabilizing the probe at each measurement point, the estimated surface position can be calculated by processing the detection data. In this case, it is possible to avoid the influence of the convergence time of each contact point on the object to be measured in the contact detection, and improve the working efficiency while maintaining high measurement accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram illustrating 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 according to the first embodiment.

FIG. 5 is a graph showing a change in a detection signal in scanning according to the first embodiment.

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

FIG. 7 is a schematic diagram illustrating a change in a detection signal according to a contact state of a 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 a 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]

DESCRIPTION OF SYMBOLS 1 Inside / outside surface measuring device 5 Detecting means 6 Personal computer 23 Support body 24 Posture operation means 31 Control means 33 Posture control means 100 Touch signal probe 101 Stylus holder 102 Stylus 102A Contact part 103A Vibration means 103B Detection means 110 Second vibration means a _n amplitude information values a ₀ to a _m is the amplitude information value group a _s reference information value D offset radius d _n pushing amount R _n estimated surface position R ₀ to R _m estimated surface position group r _n actual position r ₀ ~ r _m Actual position group W Workpiece to be measured W1 Inner peripheral surface as measurement surface

Claims (12)

[Claims] 1. A stylus that moves in a three-dimensional space at a predetermined command velocity vector in response to an external command, a stylus that is supported by the support and has a contact portion that comes into contact with an object to be measured, and the stylus. A contact detection probe including a vibration means for resonating at a frequency f1 in an axial direction and a detection means for detecting a change in vibration of the stylus by the vibration means, wherein the contact portion is provided on the surface of the object to be measured. A surface shape measuring method for measuring a surface shape of the object to be measured from a position of a support at the time of contact, wherein the contact detection probe is moved by a command of the command speed vector to measure the object to be measured. Contacting a surface to be processed, amplitude information value of the detection signal output from the detection circuit
An is while controlling the distance between the measuring surface to be such that the predetermined reference information value A _s, the contact detection probe is moved along the surface to be the measurement, and to the amplitude information value An 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 surface profile measuring method characterized by comprising the step of calculating an estimated surface position R _n which is estimated to be obtained when scanned. 2. The surface velocity measuring method according to claim 1, wherein the command velocity vector in the scanning step is set.
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 the value equivalent to a multiplied value. 3. The surface shape measuring method according to claim 1, wherein said estimated surface position R _n calculated in said calculating step is the next real position relative to said real position r _n .
After determining r _{n + 1} , the real position r _n is used as a starting point, and the next real position r _{n + 1} and the immediately preceding real position r _{n−1 have} a size corresponding to the amplitude information value An. A surface shape measuring method, characterized in that the position is a position corrected in a direction orthogonal to a straight line connecting. 4. The surface shape measuring method according to claim 1, wherein the estimated surface position R _n calculated in the calculating step starts from the actual position r _n and the amplitude information value a size corresponding to an, the surface shape measuring method, wherein the a corrected position to the actual position r _n and the previous orthogonal direction as the straight line connecting the 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 starts from the real position r _n and the amplitude information value A size corresponding to An and at least the actual position
surface, characterized in that the curve defined by r _n and three actual position r _{n + 1,} r _n-1 of the vicinity of the a corrected position in the direction of the perpendicular dropped from the actual 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 is a size corresponding to the amplitude information value An. The method for measuring a surface shape according to claim 1, further comprising an offset amount D with respect to a stylus axis of a contact portion of the stylus. 7. The surface shape measuring method according to claim 1, wherein scanning of the surface to be measured is completed first, and all the amplitude information values required for the surface during the scanning are completed. 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
A surface shape measuring method characterized by and an actual position group r ₀ ~r _m corresponding thereto to obtain an estimated surface position group R ₀ to R _m by performing the calculation. 8. The surface shape measuring method according to claim 1, wherein said contact detection probe further comprises a second vibration means for causing said stylus to resonate at a frequency f2 in a direction crossing the axis. In the scanning step, the amplitude information value An of the detection signal output from the detection circuit when the vibration by the second vibration means is at a predetermined phase is latched, 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 a direction of vibration of said stylus by said second vibrating means is substantially orthogonal to an axial direction of said stylus, and said scanning step includes: A method for measuring a surface shape, wherein the surface shape is substantially perpendicular to a moving direction of the support. 10. The surface shape measuring method according to claim 1, wherein the support has attitude manipulating means for rotating and tilting the contact detection probe to an arbitrary attitude. A method for measuring a surface shape, comprising: manipulating a posture of the contact detection probe according to a shape of an object to be measured. 11. The surface shape measuring method according to claim 10, wherein a direction of vibration of the stylus by the second vibrating means is a direction normal to a surface of the object to be contacted by the contact portion. A surface shape measuring method, wherein the posture operating means is operated as follows. 12. A surface shape measuring method according to claim 8, wherein said stylus vibrates linearly by said second vibrating means. .