JP4951270B2 - Measuring method and measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring instrument excellent in convenient use. <P>SOLUTION: In this measuring instrument 10 provided with a stylus 16: the stylus 16 is a pivot type of generating probably an error caused by a circular-arc distortion of an arm 30 within a motion plane; a work 12 has an objective face design value; and a specific point on an objective face 14 for positioning a probe 26 is indicated by a measuring axis-directional value, using a fulcrum 28 position corresponding to a shape specific point 32 as reference. This measuring instrument 10 is provided with an input means 18 using the measuring axis-directional value as an initial value, a determination means 20 for estimating the error caused by the circular-arc distortion corresponding to the initial value, based on objective face design value information and circular-arc distortion information obtained preliminarily, and for finding a determination value with the error corrected from the initial value, a driving means 22 for moving relatively the stylus 16 with respect to the work 12, and a control means 24 for controlling the driving means 22 to position the stylus 16 with respect to the work 12, based on the determination value. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a measurement method and a measurement apparatus, and more particularly to an improvement in a positioning method (mechanism) of a measurement apparatus having a pivot stylus.

Conventionally, in order to precisely measure the contour shape of a workpiece, a precision measuring device such as a contour shape measuring machine has been used (for example, Patent Document 1).
Such a precision measuring instrument includes a stylus. In the precision measuring instrument, the contour shape data on the workpiece target surface is obtained by tracing from the measurement start position on the workpiece target surface to the measurement end position with a stylus.

By the way, in a precision measuring instrument, not only high-precision precision measurement but also usability is a very important required performance.
Conventionally, it is conceivable to automate the above-described measurement in order to improve usability.

JP-A-6-273104

However, even in the conventional method, it is very difficult to accurately and easily set the measurement position, and thus it is difficult to completely automate the measurement. In the conventional method, even if a complete automatic measurement is performed, it is difficult to set the measurement position accurately and easily, so that a satisfactory measurement result may not be obtained.
Accordingly, in the field of precision measurement, although positioning is difficult, there is still room for improvement in the usability of the measuring apparatus. However, conventionally, there is no appropriate technique that can solve this problem.
The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a measurement method and a measurement apparatus that are excellent in usability.

<Correction method>
In order to achieve the above-mentioned object, the measurement method according to the present invention is a measurement method in which the workpiece target surface is traced in the measurement axis direction with a stylus and information relating to the workpiece target surface is obtained.
In the stylus, the stylus follows the workpiece surface in a movement plane defined by the measurement axis and the height axis, and the arm moves circularly around the fulcrum, causing an error due to the arc distortion of the arm. It is intended for a pivot type stylus
The workpiece has a design value related to the target surface and has a shape feature point on the target surface.
Moreover, an input process, a determination process, and a positioning process are provided.
Here, in the input step, a specific position on the workpiece target surface for positioning the stylus probe is determined based on the measurement axis direction value based on the fulcrum position corresponding to the shape feature point on the workpiece target surface. Instructed, this is the initial value.
The determining step estimates an error due to the arc distortion corresponding to the initial value input in the input step based on the target surface design value information and the arc distortion error information obtained in advance, A determination value in which the error is corrected is obtained from the initial value.
In the positioning step, the stylus and the workpiece are positioned based on the determined value obtained in the determining step.

In the measurement method according to the present invention, the workpiece is intended for a workpiece having a peak point or a bottom point as the shape feature point on the target surface. The specific position is intended for the measurement start position where the trace is started by the stylus probe and the measurement end position where the trace is ended.
In the input step, an initial value of a start position and an initial value of an end position are instructed based on the fulcrum position corresponding to the peak point or the bottom point on the workpiece target surface.
The determination step estimates an error due to the arc distortion corresponding to the initial value of the start position input in the input step based on the target surface design value information obtained in advance and the arc distortion error information, A start position determination value in which the error is corrected is obtained from the start position initial value.
The determination step estimates an error due to the arc distortion corresponding to the initial value of the end position input in the input step based on the target surface design value information and the arc distortion error information obtained in advance. Then, an end position determination value in which the error is corrected is obtained from the end position initial value.
In the positioning step, the stylus and the workpiece are positioned based on the start position determination value obtained in the determination step.
The measurement method preferably includes a measurement step.
Here, the measurement step is provided at a subsequent stage of the positioning step, and a desired area on the workpiece target surface is traced by the stylus based on the start position determination value and the end position determination value, and the workpiece target Get information about a face.

In the measurement method according to the present invention, it is preferable that the determination step includes a height information acquisition step, an error information acquisition step, and a correction step.
Here, in the height information acquisition step, a height axis direction value of a point on the workpiece target surface corresponding to the initial value is obtained using target surface design value information on the workpiece obtained in advance.
The error information acquisition step uses the arc distortion error information obtained in advance to calculate an error in the measurement axis direction value due to the arc distortion corresponding to the height axis direction value obtained in the height information acquisition step. Ask.
In the correction step, a value obtained by removing the error obtained in the error acquisition step from the initial value is set as the determined value.

  In the measuring method according to the present invention, it is preferable that the workpiece is one that has been leveled and peaked or bottomed.

<Measurement device>
Further, in order to achieve the above object, a measuring apparatus according to the present invention is a measuring apparatus that traces a workpiece surface with a stylus in a measuring axis direction and acquires information on the workpiece surface.
In the stylus, the stylus follows the workpiece surface in a movement plane defined by the measurement axis and the height axis, and the arm moves circularly around the fulcrum, causing an error due to the arc distortion of the arm. The target is a pivot stylus.
The workpiece has a design value related to the target surface and has a shape feature point on the target surface.
The measuring apparatus includes an input unit, a design value information storage unit, an error information storage unit, a determination unit, a driving unit, and a control unit.
Here, the input means uses a specific position on the workpiece target surface for positioning the stylus probe as a measurement axis direction value based on the fulcrum position corresponding to the shape feature point on the workpiece target surface. Instructed, this is the initial value.
The design value storage unit stores target surface design value information representing a relationship between a measurement axis direction value of a point on the workpiece target surface and a height axis direction value obtained in advance.
The error information storage unit stores arc distortion error information representing a relationship with a measurement axis direction value error corresponding to a height axis direction value of the stylus arm obtained in advance.
The determining means is configured to determine the arc distortion corresponding to the initial value input in the input step based on the target surface design value information in the design value information storage section and the arc distortion error information in the error information storage section. An error due to is estimated, and a determined value in which the error is corrected is obtained from the initial value.
The driving means performs relative movement between the stylus and the workpiece.
The control means controls the operation of the driving means so that the stylus and the workpiece are positioned based on the determined value obtained in the determining step.

In the measuring apparatus according to the present invention, the workpiece is intended for a workpiece having a peak point or a bottom point as the shape feature point on the target surface. The specific position is intended for the measurement start position where the trace is started by the stylus probe and the measurement end position where the trace is ended.
The input means instructs a start position initial value and an end position initial value based on the fulcrum position corresponding to the peak point or the bottom point on the workpiece target surface.
The determining means corresponds to the start position initial value input in the input step based on the target surface design value information of the design value information storage unit and the arc distortion error information of the error information storage unit. An error due to the arc distortion is estimated, and a start position determination value in which the error is corrected is obtained from the start position initial value. The determining means estimates an error due to the arc distortion corresponding to the initial position initial value input in the input step based on the target surface design value information and the arc distortion error information, and An end position determination value in which the error is corrected is obtained from the value.
The control means positions the stylus and the work on the basis of the start position determined value obtained by the determining means, and on the work target surface based on the start position determined value and the end position determined value. It is preferable to control the operation of the driving means so that a desired region of the image is traced by the stylus.

In the measurement apparatus according to the present invention, it is preferable that the determination unit includes a height information acquisition unit, an error information acquisition unit, and a correction unit.
Here, the height information acquisition unit obtains the height axis direction value of the point on the workpiece target surface corresponding to the initial value, using the target surface design value information regarding the workpiece in the design value information storage unit. .
Further, the error information acquisition unit uses the arc distortion error information of the error information storage unit to determine the measurement axis direction value by the arc distortion corresponding to the height axis direction value obtained by the height information acquisition unit. Find the error.
The correction unit sets a value obtained by removing the error obtained by the error information acquisition unit from the initial value as the determined value.

  Here, the initial value and the determined value are not related to the point on the work target surface, but are related to the position of the fulcrum in the measurement axis direction. The fulcrum position of the present invention can be specified based on, for example, measurement axis direction value information from the pickup mechanism.

According to the measurement method according to the present invention, since the input step, the determination step, and the measurement step are provided, it is possible to improve the usability of the measurement apparatus including a pivot stylus.
Further, according to the measuring apparatus of the present invention, the input device, the design value information storage unit, the error information storage unit, the determination unit, the driving unit, and the control unit are provided. Therefore, it is possible to improve the usability of the measuring apparatus provided with the pivot stylus.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of a measuring apparatus for performing a measuring method according to an embodiment of the present invention.
The contour shape measuring machine (measuring device) 10 shown in the figure assumes an aspherical workpiece 12 having an aspherical design value (target surface design value) as an aspherical expression as the workpiece 12. The shape of the aspherical surface (target surface) 14 of the aspherical workpiece 12 in the XZ sectional direction is symmetrical with respect to the central axis.
In the present embodiment, the aspherical workpiece 12 is intended for a workpiece that has been leveled and peaked (or bottomed out).

For this purpose, the contour shape measuring machine 10 includes a pickup mechanism 17 for the pivot stylus 16, an input unit 18, a determination unit 20, a drive unit 22, and a control unit 24.
Here, in the pivot type stylus 16, the stylus arm 30 moves in an arc around the fulcrum 28 in the XZ plane (the plane to be moved), the tracing stylus 16 of the stylus 16 following the aspherical surface 14 of the workpiece 12.
The input means 18 uses the position (X value) of the fulcrum 28 corresponding to the peak point 32 on the aspheric surface (target surface) 14 of the aspheric surface work 12 as a reference, the initial value (Xs) of the measurement start position, and the measurement end. The initial position value (Xe) is indicated by the X value (measurement axis direction value).

  The determination unit 20 is made of software executed on the computer 34, for example, and includes a design value information storage unit 36 and an error information storage unit 38.

The design value information storage unit 36 stores aspheric design value information (for example, an expression representing an aspheric surface) that represents the relationship between the X value and the Z value of a point on the aspheric surface 14 obtained in advance.
The error information storage unit 38 stores arc distortion error information representing a relationship with an error caused by arc distortion of the stylus arm 30 obtained in advance, that is, an X value error corresponding to the Z value of the stylus arm 30.

Then, when the start position initial value (Xs) is input, the determination unit 20 uses the workpiece design value information in the design value information storage unit 36 and the arc distortion error information in the error information storage unit 38 to start the initial position initial value. From the value (Xs), the start position determination value (Xs ′) in which the error (dx _{0 (s)} ) due to the arc distortion is corrected is obtained. Further, when the end position initial value (Xe) is input, the determining means 20 uses the workpiece design value information in the design value information storage unit 36 and the arc distortion error information in the error information storage unit 38 to determine the end position initial value. From the value (Xe), an end position determination value (Xe ′) in which the error (dx _{0 (e)} ) due to the arc distortion is corrected is obtained.

Moreover, the drive means 22 is provided with the drive circuit 40 and the X-axis feeder 42, for example. The driving means 22 relatively moves the contact position (measurement position) between the stylus 16 and the workpiece 12 in the X-axis direction.
The control means 24 consists of software etc. which are run on the computer 34, for example. The control means 24 is configured so that a desired area on the workpiece 12 is traced by the pivot stylus 16 based on the start position determination value (Xs ′) and the end position determination value (Xe ′) with respect to the position of the fulcrum 28. In addition, the operation of the driving means 22 is controlled.

The determination unit 20 includes a height information acquisition unit 44, an error information acquisition unit 46, and a correction unit 48.
Here, when the start position initial value (Xs) is input, the height information acquisition unit 44 uses the workpiece design value information in the design value information storage unit 36 to correspond to the Z corresponding to the start position initial value (Xs). A value (Zs) is obtained.
When the end position initial value (Xe) is input, the Z value information acquisition unit 30 uses the workpiece design value information in the design value information storage unit 36 to determine the Z value (Xe) of the end position initial value (Xe). Ze) is obtained.

The error information acquisition unit 46 uses the arc distortion error information in the error information storage unit 38 to obtain an error dx _{0 (s)} of the X value due to the arc distortion corresponding to the Z value (Zs) of the start position expected value.
Further, the error information acquisition unit 46 uses the arc distortion error information in the error information storage unit 38 to calculate the error dx _{0 (e)} of the X value due to the arc distortion according to the Z value (Ze) of the initial value of the end position. Ask.

The correction unit 48 obtains a start position determination value (Xs ′ = Xs ± dx _{0 (s)} ) in which the error dx _{0 (s)} due to the arc distortion is corrected with respect to the start position initial value (Xs).
Further, the correction unit 34 obtains an end position determination value (Xe ′ = Xe ± dx _{0 (e)} ) in which the error dx _{0 (e)} due to the arc distortion is corrected with respect to the initial value (Xe) of the end position. .

  In the present embodiment, the aspherical workpiece 12 has been leveled and peaked.

  In the present embodiment, the aspherical design value information is newly input to the design value information storage unit 36 using the input unit 18 or the existing aspherical design stored in the design value information storage unit 36 is used. You can also change the value information.

In the present embodiment, the XZ coordinate value information of the measuring element 26 is obtained based on the XZ coordinate value information from the pickup mechanism 17. Based on the XZ coordinate value information of the stylus 16, XZ coordinate value information on the workpiece aspheric surface 14 is obtained. Based on the XZ coordinate value information on the work aspheric surface 14, the contour shape of the aspheric surface 14 is obtained.
For this purpose, the present embodiment includes an X value detector 52, a Z value detector 54, and data processing means 56.

In the present embodiment, the aspherical surface 14 can be evaluated as a surface by obtaining XZ cross-sectional shape data from a plurality of different Y values of the same workpiece 12.
For this purpose, in this embodiment, a Y-axis table 58, a Y-value detector 60, and a Y-axis feed device 62 are provided.

  In the present embodiment, the leveling and peaking are completed while the aspherical workpiece 12 is placed on the Y-axis stage 58 as a reference plane.

In the present embodiment, the control unit 24 controls the operation of the driving unit 22 as follows.
That is, in the present embodiment, the position of the fulcrum 28 is estimated based on the X value information from the X value detector 52.
The control means 24 measures a desired region on the aspherical surface 14 of the workpiece 12 (for example, left and right even with respect to the peak point 32), so that the fulcrum 28 position based on the X value information from the X value detector 52 is The operation of the driving means 22 is controlled so that the start position determination value (Xs ′) and the end position determination value (Xe ′) are obtained.

The contour shape measuring machine 10 according to the present embodiment is configured as described above, and the operation thereof will be described below.
That is, in this embodiment, since the measurement position on the workpiece 12 is set based on the aspherical design value information of the workpiece 12 and the arc distortion error information obtained in advance, the pivot stylus 16 is provided. The measurement position with respect to the contour shape measuring machine 10 can be determined accurately and easily.
Therefore, in the present embodiment, the contour shape measuring machine 10 including the pivot stylus 16 can be positioned at a desired measurement position.
Thereby, in this embodiment, the desired area | region on the workpiece | work 12 can be set to a measurement area | region more reliably and easily. For example, with respect to the work 12 whose XZ cross section of the target surface 14 is bilaterally symmetric, the measurement region can be set to be bilaterally symmetric more reliably and easily, so that the usability of the contour shape measuring machine 10 including the pivot type stylus 16 is improved. Will improve dramatically.

The present invention has been made paying attention to the following points.
That is, in the field of contour shape measurement, an aspherical workpiece 12 may be used as a workpiece, and since the cross section of the aspherical workpiece 12 is symmetric, there is a demand for the measurement region to be symmetric.
However, in a measuring machine having a mechanism with an arc motion such as the contour shape measuring machine 10 having the pivot type stylus 16, the arc distortion of the arm 30 occurs. Distortion in the X-axis direction occurs at the position.
Therefore, in the contour shape measuring machine 10 including the pivot stylus 16, it is difficult to determine the measurement start position and the measurement end position due to the arc distortion of the arm 30.
Due to the error in the X-axis direction due to the arc distortion of the arm 30 as described above, if the measurement position is determined equally on the left and right with reference to the value of the measurement axis (X-axis), as shown in FIG. In addition, it is impossible to measure the workpiece 12 evenly on the aspherical surface 14 with the peak point 32 as the center.
That is, even if the start position and the end position are set equally on the left and right with reference to the position of the fulcrum 28 corresponding to the peak point 32 on the aspheric surface 14 of the work 12, the actual measurement region on the aspheric surface 14 of the work 12 May not be equal left and right.

In order to avoid this, usually, the following various methods are considered.
(1) A measurer determines a measurement start position and a measurement end position by intuition.
(2) Determine the measurement start position and measurement end position by actually applying a stylus to the workpiece.
(3) Measure beyond the effective range of the aspheric surface, and delete unnecessary parts during analysis.

However, even with the general method, there is still room for improvement in terms of accuracy and ease of determination of the measurement position.
On the other hand, the present inventor has first elucidated that the cause of the defect related to the measurement position is the error caused by the arc distortion as described above.
Then, based on the elucidation of the cause, the present inventors can determine the correct measurement position based on the workpiece design value information and the arc distortion error information if the workpiece has a design value related to the target surface. As a result, the present invention has been completed.

Therefore, in the present embodiment, the following is performed.
(1) The Z value of the point on the aspheric surface corresponding to the X value of the measurement position is obtained based on the aspheric design value.
(2) An error in the X-axis direction that will occur according to the Z value of a point on the aspheric surface is calculated.
(3) The measurement position is corrected by the calculated error in the X-axis direction.

Thus, in this embodiment, since the error in the X-axis direction due to the arc distortion of the arm 30 is corrected, even if the measurement position is determined based on the value of the measurement axis (X-axis), FIG. As shown in FIG. 4, the left and right sides of the aspherical surface 14 of the workpiece 12 can be measured equally on the basis of the peak point 32.
That is, in the present embodiment, the measurement start position (X value) and measurement end position (X value) of the fulcrum 28 are set so that the measurement area on the aspherical surface 14 of the actual work 12 is equal left and right. It is.

Hereinafter, the operation will be described more specifically with reference to FIG.
That is, in the present embodiment, when measuring the aspherical workpiece 12, it is very important to perform the preparation step (S10) in order to accurately position the measurement surface.
For this purpose, in the preparation step (S10), leveling and peaking (bottoming) are performed.
As described above, in the present embodiment, since the preparation step (S10) is performed prior to measuring the aspherical workpiece 12, the following work for measuring the aspherical workpiece 12 can be performed more accurately. .

And this embodiment performs an input process (S12) after completion of the said preparation process (S10).
That is, in the input step (S12), the specific position on the workpiece target surface where the stylus probe is positioned is indicated by the X value based on the fulcrum position corresponding to the shape feature point on the workpiece target surface. Use the initial value.
As a result, in the input step (S12), the initial value of the measurement start position and the end position of the measurement are based on the pivot point position of the pivot stylus corresponding to the peak point 32 on the aspherical surface 14 of the aspherical workpiece 12. The initial value can be indicated.

After the completion of the input step (S12), a determination step (S14) is performed.
That is, in the determination step (S14), the error due to the arc distortion corresponding to the initial value is estimated based on the aspheric design value information and the arc distortion error information obtained in advance, and the error is corrected from the initial value. Find the decision value.

In the present embodiment, the determination step (S14) includes a height information acquisition step (S16), an error information acquisition step (S18), and a correction step (S20).
Here, in the height information acquisition step (S16), the Z value of the point on the aspheric surface corresponding to the initial value (X value) is obtained using the aspheric design value obtained in advance.
Further, in the error information acquisition step (S18), the error of the X value due to the arc distortion corresponding to the Z value obtained in the height information acquisition step (S16) is obtained using the arc distortion error information obtained in advance. .
In the correction step (S20), a value obtained by removing the error obtained in the error information acquisition step (S18) from the initial value is set as the determination value. Also. In this correction step (S20), when there is no error corresponding to the initial value, the initial value is set as the designated value as it is.
Thus, in the determination step (S14), an error due to the arc distortion corresponding to the start position initial value is estimated based on the aspherical meter value information and arc distortion error information obtained in advance, and the start position initial value is determined. From this, it is possible to obtain a starting position determination value in which the error is corrected.
In the determination step (S14), similarly to the start position, an error due to the arc distortion corresponding to the initial value of the end position is estimated based on the aspheric design value information obtained in advance and the arc distortion error information. Then, the end position determination value in which the error is corrected can be obtained from the end position initial value.

After completion of the determination step (S14), a positioning step (S22) is performed.
In the positioning step (S22), the stylus and the workpiece are positioned based on the determined value obtained in the determining step (S14).
In the positioning step (S22), the stylus and the workpiece can be positioned such that the fulcrum position of the pivot stylus becomes the start position determination value obtained in the determination step (S14).

After the positioning step (S22) is completed, a measurement step (S24) is performed.
That is, in the measurement step (S24), tracing (measurement) is started from a state in which the pivot point of the pivot stylus is positioned at the start position determination value.
Then, tracing (measurement) is performed until the fulcrum position of the pivot stylus shows the end position determination value, and the tracing (measurement) is completed.

As described above, in this embodiment, it is possible to set the measurement start position and the measurement end position from which the influence of the error due to the arc distortion is removed.
For this reason, it was difficult to set the measurement area of the aspherical workpiece symmetrically in the past, but in this embodiment, the measurement position is measured using the aspherical design value and the arc distortion error information. By correcting the above, it is possible to accurately and easily make the measurement region symmetrical with respect to the peak point.

In the present embodiment, the height information acquisition, the error information acquisition, and the calculation for correction are performed by a determination unit made of software or the like.
For this reason, in this embodiment, these calculations can be performed more easily. In addition, in the present embodiment, there is no room for personal errors in these calculations, so that the measurement position can be determined more accurately.
In this embodiment, since the measurement position determined in this way is automatically performed by the control means made of software or the like, positioning and measurement can be performed accurately and easily. Thereby, in this embodiment, the usability of the contour shape measuring machine 10 provided with the pivot type stylus 16 is improved.

Next, a more specific calculation method of the measurement position will be described.
That is, as shown in FIG. 4, the relationship between the Z position of the pivot stylus and the error can be expressed by Equation 1 below.

したがって、Ｘ軸方向誤差、Ｚ値は、それぞれ下記の数式２，３で表せる。

Therefore, the X-axis direction error and the Z value can be expressed by the following formulas 2 and 3, respectively.

  Here, in the above formula, L is the stylus arm length, h is the stylus edge length, and θ is the stylus arm angle.

Also, to represent the aspherical design values in formulas 4 and 5 below, a peak point of the aspheric workpiece so (bottom point) X = 0.0, Z value at X = _{X 0} is Z = lens _(X 0) So, the error dX ₀ in the X-axis direction in the X = _{X 0} can be expressed by equation 6 below.

In the present embodiment, the designation of the measurement start position and measurement end position for the fulcrum 28 of the pivot stylus 16 is shifted from the initial value by an error dX ₀ minutes. This is the decision value.

As described above, according to the present embodiment, in the contour shape measuring machine 10 including the pivot stylus 16, the measurement start position and the measurement end position with respect to the fulcrum 28 of the pivot stylus 16 are determined in consideration of the arc distortion of the arm 30. Thus, the measurement start position and measurement end position on the workpiece can be determined easily and accurately.
Therefore, according to the present embodiment, with respect to the contour shape measuring machine 10 including the pivot stylus 16, positioning to a desired measurement position on the workpiece and measurement of a desired area on the workpiece can be accurately and easily performed. Therefore, the usability of the contour shape measuring machine 10 including the pivot stylus 16 is improved.

Modification <Aspherical>
In this embodiment, the workpiece can be a spherical surface instead of an aspherical surface. This is because, for example, the mathematical expression 4 representing the aspherical design value includes a general quadratic curve (circle, hyperbola, parabola), so that the workpiece can be applied as it is to a spherical surface that is not an aspherical surface.

<Convex workpiece>
In the present embodiment, the workpiece can be a concave one instead of the convex one. In the case of a concave work, it becomes the bottom point instead of the peak point.

It is explanatory drawing of schematic structure of the measuring apparatus for performing the measuring method concerning one Embodiment of this invention. It is explanatory drawing of the attention point which came to the elucidation of the cause of this invention, and the subject solution means of this invention. It is a flowchart which shows the process sequence of the measuring method concerning this embodiment. It is explanatory drawing of the specific calculation method of the measurement position by this embodiment.

Explanation of symbols

10 Contour shape measuring machine (measuring device)
12 Aspherical workpiece (workpiece)
14 Aspherical surface (target surface)
16 Pivot stylus 18 Input means 20 Determination means 22 Drive means 24 Control means

Claims (7)

In a measuring method of tracing information on a workpiece target surface by tracing the workpiece target surface with a stylus probe in the measurement axis direction,
In the stylus, the stylus follows the workpiece surface in a movement plane defined by the measurement axis and the height axis, and the arm moves circularly around the fulcrum, causing an error due to the arc distortion of the arm. It is intended for a pivot type stylus
Further, the workpiece has a design value related to the target surface and has a shape feature point on the target surface,
A specific position on the workpiece target surface for positioning the stylus probe is indicated by the measurement axis direction value based on the fulcrum position corresponding to the shape feature point on the workpiece target surface, and this is set as an initial value. Input process;
Based on the target surface design value information obtained in advance and the arc distortion error information, an error due to the arc distortion corresponding to the initial value input in the input step is estimated, and the error is calculated from the initial value. A decision step for obtaining a corrected decision value;
A positioning step for positioning the stylus and the workpiece based on the determined value obtained in the determining step;
A measurement method characterized by comprising: The measurement method according to claim 1,
The workpiece is intended to have a peak point or a bottom point as the shape feature point on the target surface,
The specific position is intended for a measurement start position for starting a trace with the stylus probe and a measurement end position for ending the trace,
The input step indicates an initial value of the start position and an initial value of the end position with reference to the fulcrum position corresponding to the peak point or the bottom point on the workpiece target surface,
The determination step estimates an error due to the arc distortion corresponding to the initial value of the start position input in the input step based on design value information on the target surface obtained in advance and the arc distortion error information. , Obtaining a start position determination value in which the error is corrected from the start position initial value,
Further, the determining step estimates an error due to the arc distortion corresponding to the end position initial value input in the input step based on the target surface design value information and the arc distortion error information obtained in advance, An end position determination value in which the error is corrected is obtained from the end position initial value,
The positioning step performs positioning of the stylus and the workpiece based on the start position determination value obtained in the determination step,
In addition, the method includes a measurement step of tracing a desired area on the work target surface with the stylus based on the start position determination value and the end position determination value, and acquiring information on the work target surface. Measuring method to do. In the measuring method of Claim 1 or 2,
The determination step uses a target surface design value information on the workpiece obtained in advance, and obtains a height information acquisition step for obtaining a height axis direction value of a point on the target surface corresponding to the initial value;
Using the previously obtained arc strain error information, an error information obtaining step for obtaining an error in the measurement axis direction value due to the arc strain corresponding to the height axis direction value obtained in the height information obtaining step;
A correction step in which the determined value is a value obtained by removing the error obtained in the error information acquisition step from the initial value;
A measurement method characterized by comprising: In the measuring method in any one of Claims 1-3,
The measuring method is characterized in that the workpiece is intended for leveling and for which peaking or bottoming has been completed. In a measuring device that traces the workpiece surface with a stylus in the measurement axis direction and acquires information about the workpiece surface,
In the stylus, the stylus follows the workpiece surface in a movement plane defined by the measurement axis and the height axis, and the arm moves circularly around the fulcrum, causing an error due to the arc distortion of the arm. It is intended for a pivot type stylus
The workpiece has a design value related to the target surface, and has a shape feature point on the target surface,
A specific position on the workpiece target surface for positioning the stylus probe is indicated by the measurement axis direction value with reference to the fulcrum position corresponding to the shape feature point on the workpiece target surface, and this is designated as an initial value. Input means to
A design value information storage unit storing target surface design value information representing a relationship between a measurement axis direction value and a height axis direction value of a point on the workpiece target surface obtained in advance;
An error information storage unit that stores arc distortion error information representing a relationship with an error of a measurement axis direction value corresponding to a height axis direction value of the stylus arm obtained in advance;
Based on the target surface design value information in the design value information storage unit and the arc distortion error information in the error information storage unit, an error due to the arc distortion corresponding to the initial value input in the input step is estimated. Determining means for obtaining a determined value in which the error is corrected from the initial value;
Driving means for relatively moving the stylus and the workpiece;
Control means for controlling the operation of the driving means so that the stylus and the workpiece are positioned based on the determined value obtained by the determining means;
A measuring apparatus comprising: The measuring apparatus according to claim 5, wherein
The workpiece is intended to have a peak point or a bottom point as the shape feature point on the target surface,
The specific position is intended for a measurement start position for starting a trace with the stylus probe and a measurement end position for ending the trace,
The input means indicates the initial value of the start position and the initial value of the end position with reference to the fulcrum position corresponding to the peak point or the bottom point on the workpiece target surface,
The determining means corresponds to the start position initial value input in the input step based on the target surface design value information of the design value information storage unit and the arc distortion error information of the error information storage unit. An error due to arc distortion is estimated, and a start position determination value in which the error is corrected is obtained from the start position initial value,
Further, the determining means is configured to determine the arc distortion corresponding to the initial value of the end position input by the input means based on the target surface design value information of the design value storage section and the arc distortion error information of the error information storage section. The end position determination value in which the error is corrected is calculated from the end position initial value,
The control means positions the stylus and the workpiece based on the start position determined value obtained by the determining means, and based on the start position determined value and the end position determined value on the workpiece target surface. A measuring apparatus for controlling the operation of the driving means so that a desired region of the image is traced by the stylus. The measuring apparatus according to claim 5 or 6,
The determination means uses a target surface design value information of the design value information storage unit, and obtains a height information acquisition unit for obtaining a height axis direction value of a point on the workpiece target surface corresponding to the initial value;
Using the arc distortion error information of the error information acquisition unit, an error information acquisition unit for obtaining an error of the measurement axis direction value due to the arc distortion corresponding to the height axis direction value obtained by the height information acquisition unit;
A correction unit that sets a value obtained by removing the error obtained by the error information acquisition unit from the initial value as the determination value;
A measuring apparatus comprising:

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