JP2008008879A - Measuring instrument, measuring reference, and precision machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out highly precise measurement for a plane shape by scan of displacement gages. <P>SOLUTION: This measuring instrument is provided with the four displacement gages as total of the displacement gage Da for detecting axial going-in-and-out under rotation, when measuring irregularity along a circle of radius r on a face by rotation scan of the displacement gage Db, and a displacement gage Dc and a displacement gage Dd for executing scan measurement along the circle of radius r, on a straight line connecting measuring points of the displacement gage Da and the displacement gage Db. The circle of radius r is formed into a shape concentric to a rotation scan shaft and located on a reference circular ring SC disposed to be rotated reversely also to a position rotated 180° relatively to the circle of radius r, and a rotation motion error of the reference circular ring SC for the scan, the circle of radius r and an irregular shape along the circle of radius r are separation-identified by selecting six as total to be used out of outputs from the four displacement gages in the rotation scan before and after an reversal operation of the reference circular ring SC. The irregular shape along the circle obtained as a result therein is combined mathematically with irregular shapes along the straight lines obtained the plurality of straight lines, using another method to constitute the plane correctly. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a precise straight shape and planar shape measurement technique and fabrication technique, and more particularly to a measurement apparatus, a measurement standard, and a precision machine tool.

  The need to measure long straight shapes and large area planar shapes with high precision is increasing due to the increase in the length of precision coating tools, the enlargement of wafers, and the increase in the area of LCD screens. The certainty of the metrics given is no longer limited. Therefore, there is a need for a measurement method based on mathematically given standards that does not rely on physical standards.

At present, it is known that a straight shape along a straight line in a vertical plane where no deflection due to gravity occurs can be measured with mathematical precision by an improved inversion method, and has already been put into practical use (see Non-Patent Document 1). ).
Tsuji, Jun Shimizu, Makoto Ooo: Straightness measurement by the improved inversion method, Journal of the Japan Society for Precision Engineering, 66-10 (2000) 1578-1602

  Conventionally, a method for measuring an uneven shape (straight shape) in the height direction along a circumference that has not been known has been a problem without being affected by a rotational scanning motion error or its repetition error. Conventionally, in order to measure the planar shape mathematically correctly, there is only known a method for obtaining a plurality of orthogonal linear shapes and diagonal linear shapes by an improved inversion method. The challenge was to build a realistic method for correctly measuring a large plane in a difficult way. Furthermore, the conventionally known reversal method is a method that cannot eliminate the influence of deflection due to gravity, and the issue for the industry is how to perform highly accurate planar shape measurement other than the vertical plane.

  The present invention realizes a straight shape measurement that is mathematically correct along a circumference, and further measures a straight shape along a conventional straight line without being affected by a scanning motion error or its repetition error. In combination with the inversion method, it provides a method for mathematically measuring the planar shape in the vertical plane. Furthermore, paying attention to the fact that the improved inversion method can be applied to the measurement of the surface shape in the horizontal plane as long as the auxiliary sample is not deflected due to gravity, and as the auxiliary sample, a long-axis cylindrical end surface or an end surface of a sufficiently high plate A method of using is provided.

The measuring apparatus according to claim 1, wherein the measuring apparatus measures the surface shape of the disk to be measured.
A rotating table that supports and rotates the disk to be measured;
A reference ring arranged concentrically with the disk to be measured and rotating together with the rotary table;
A first displacement meter A that detects a displacement in a surface vertical direction at a rotation center point a on the surface of the disk to be measured and outputs a first signal;
A second displacement meter B for detecting a displacement in a direction perpendicular to the surface from a rotation center point a to a point b having a radius r on the surface of the disk to be measured, and outputting a second signal;
A third displacement meter C for detecting a displacement in the direction perpendicular to the surface and outputting a third signal at a point c where a line passing through the rotation center points a and b intersects a circle of radius R on the reference ring; ,
A fourth displacement that detects a displacement in the direction perpendicular to the surface and outputs a fourth signal at a point d that intersects with a circle of radius R on the reference ring that is shifted from the point c by 180 degrees with respect to the rotation center point a. A total of D and
When the measurement is performed while rotating the rotary table, the output value obtained based on the first signal, the second signal, and the third signal is used as the first group data, When the measurement is performed while reversing 180 degrees and rotating the rotary table, an output value obtained based on the first signal, the second signal, and the fourth signal is used as the second data group. From the calculation using both data groups, the rotational motion error of the shaft and the surface shape along the radius r and radius R are obtained.

  More specifically, the disk to be measured can be rotated concentrically and integrally with the disk to be measured in the vertical plane attached to the horizontal rotating shaft or the rotating table. A reference circle which has a reference ring and can be arranged so as not to change in the shape of the reference ring at a position rotated 180 degrees around the rotation axis with respect to the disk to be measured. A displacement gauge A having a ring fixing jig for detecting a displacement of the center point a of the disk to be measured in a direction perpendicular to the disk surface, and a direction perpendicular to the disk surface at a point b having a radius r on the disk surface A displacement meter B that detects the displacement of the disk surface, and a displacement meter C that detects the displacement in the direction perpendicular to the disk surface at a point c where a line passing through points a and b intersects a circle of radius R on the reference ring. And recording the output of the three displacement meters during one rotation of the rotating shaft, and then the reference ring and displacement meter After placing C at a position that is inverted 180 degrees relative to the disk to be measured, obtain the output of the three displacement gauges during one rotation of the rotating shaft once again. From the total of six output data, the shape of the disk to be measured and the reference annulus, the axial displacement that occurs during the rotation of the rotating shaft, and the displacement due to the tilt of the shaft that occurs during the rotating shaft along each circumference Calculate the separation of the measured output component to correctly measure the uneven shape along the circumference of the radius r of the disk to be measured, and calibrate the uneven shape along the circumference of the radius R of the reference ring as a reference By using it, it is a measuring apparatus which measures the uneven | corrugated shape along the circumference of the arbitrary radii of the said to-be-measured disc.

  Furthermore, the present invention provides a structure in which the end surface of the cylinder having a reference ring is sufficiently long to prevent deformation of the end surface of the cylinder due to the influence of gravity when rotating and re-fixing for reversal. 2. An uneven shape along the circumference of the same principle as described in claim 1, wherein the measuring device is a structure capable of measuring the shape of a flat disk placed inside.

  Furthermore, in the present invention, in order to measure a straight shape along the diameter of the disk to be measured by a method called an improved reversal method, the sensitivity axes are aligned in a direction perpendicular to the surface of the disk to be measured. A stage that moves in the diameter direction of the disk to be measured by mounting three displacement sensors in a plane that includes one diameter of the disk to be measured along a straight line perpendicular to the diameter and mounted as a unit, and a circle to be measured An improved reversal method comprising a straightness measuring unit having a reference straight ruler that can be reversed about an axis parallel to the diameter of the plate, and a concave / convex shape measuring unit in a direction perpendicular to the disk surface along the circle according to claim 1. Calibrate the straight shape of the reference ring and the reference straight ruler as a reference, and use the straight shape along multiple straight lines of the disk to be measured measured based on the calibration results, and the straight shape along multiple concentric circles. Configure the surface shape of the disk to be measured and change the planar shape in the vertical plane. A measuring device for constant for.

  Furthermore, in addition to the above-described measuring apparatus, the present invention is an improved type in which the end face of a plate having a height such that the deflection of the end face is sufficiently smaller than the uncertainty allowed for measurement is used as a reference straight ruler. A measuring unit that measures the linear shape on the diameter of the disk to be measured in the horizontal plane using the inversion method, and the plane of the disk to be measured in the horizontal plane from the plurality of diameters of the disk to be measured and the unevenness on the circumference This is a measuring device based on the same principle and having a structure for measuring the shape.

  Furthermore, the present invention is a machine tool for processing a precise flat surface or spherical surface, and has a structure in which one or both of the reference ring and the reference straight ruler are built in or attached as necessary. Then, the work surface of the work piece, or the shaft end face that fixes the work piece or the work attachment surface that rotates integrally with the work piece is structured so that it can be measured as the disk to be measured. This is an ultra-precision machine tool that can inspect the accuracy of the machining surface, the shaft end surface, the workpiece mounting surface, or the movement accuracy of the machine tool.

  Furthermore, the present invention is a machine tool for processing a precise plane or spherical surface, and has a built-in reference that can be used for measurement, like the auxiliary wheel after calibration, the reference straight ruler, or The auxiliary wheel that has been calibrated that can be used as the reference when necessary, and a jig part that can be attached to and detached from the reference straight ruler, and a work surface of the work piece or a shaft end face for fixing the work piece, It is an ultra-precision machine tool that can measure the shape accuracy of the workpiece mounting surface that rotates together with it or the motion accuracy of the machine tool.

  Furthermore, the present invention provides a relatively long hollow cylinder containing two orthogonal plates in a diameter position, and the opening and closing movement in which the irregularities in the cylindrical axis direction at both ends of the plate orthogonal to the circumference of both ends of the cylinder are calibrated. And a linear motion measurement standard or a comparison standard for measuring a straight shape and a planar shape.

  Further, according to the present invention, the two cylinders are coaxial and relatively long cylinders connected by a plurality of plates overlapping the diameter, and the inner cylinder is hollow so that a rotating shaft or the like can be inserted. This is a linear and flat motion measurement standard or a straight and flat shape measurement comparison standard in which the cylindrical concavo-convex shape of the cylindrical end surface and the end surface of the plate connecting the cylinders is calibrated.

  Furthermore, the present invention has a reference ring that is coaxial with the rotation axis and does not rotate in order to inspect the straightness of movement of a large plane, and detects irregularities of the reference ring on the diameter of the reference ring. 1 in the direction to detect, 1 in the direction to detect the unevenness of the plane, 3 in total in the direction to detect the plane on the rotation axis, or 2 displacement meters installed in the direction to measure the plane A total of four displacement meters, including another displacement meter on a straight line, are attached to a displacement meter support arm that rotates with the rotation axis, and the displacement meter is rotated by the displacement meter and the reference ring placed at the center of rotation. Measure the straightness along two concentric circles drawn on the plane with one displacement meter, while detecting and correcting the movement error of the rotation axis tilt and the axial movement. Two-axis three-point method separates the shape of two orthogonal planes and the straightness of movement It is a measuring device that calculates the surface shape using a straight shape on the circumference and a straight shape of two orthogonal axes.

  Furthermore, the present invention uses a non-calibrated reference ring instead of the reference ring, and performs measurement before and after reverse scanning in which the reference ring is rotated 180 degrees relative to the rotation axis. Therefore, it is a measuring device that realizes the improved inversion method and can calibrate the reference ring on the spot.

  The present invention provides a correct method for measuring a planar shape that has not been known so far. Furthermore, it is possible to measure a straight cross-sectional shape and a planar shape including the influence of deflection due to gravity with a certainty that is satisfactory from an engineering standpoint. In the future, it will be possible to measure the planar shape of large planes, which will be increasingly in demand, and the motion accuracy of large machine tools to create such planes.

  According to a second aspect of the present invention, there is provided a measuring apparatus according to the first aspect of the present invention, further comprising a stage for moving the second displacement meter B in the diameter direction of the disk to be measured, and the second displacement meter by the stage. Included in the second signal by using two of the first, third, and fourth signals using the reference circle constructed while moving B in the diameter direction of the disk to be measured. The rotational motion error is corrected, and shape data at a desired radius r on the disk is obtained from the second signal.

  According to a third aspect of the present invention, there is provided a measuring apparatus according to the first aspect of the invention, further comprising a stage for moving the second displacement meter B in the diameter direction of the disk to be measured. B is moved in the diameter direction of the disk to be measured to obtain the second signal on circles having different radii. In addition, when the straight shape of the reference ring is calibrated at the nest in the device of claim 1, even if the displacement meter A is removed, only the displacement meters C and D of claim 1 are in rotation. Axial entry / exit and shaft tilt error can be corrected.

  According to a fourth aspect of the present invention, there is provided the measuring apparatus according to the third aspect, wherein a reference straight ruler having a surface facing the disk to be measured and a rear surface on the back side in parallel with the disk to be measured. A displacement meter Q for detecting displacement in the vertical direction of the front surface of the reference straight ruler, and a displacement meter R for detecting displacement in the reverse direction of the back surface of the reference straight ruler. And moving the stage in the diameter direction of the disk to be measured, the signals output from the three displacement meters B, Q, R are set as the first signal group, and then the reference straight ruler When the signals output from the three displacement meters B, Q, and R are used as the second signal group while moving the stage in the diameter direction of the disk to be measured with the front and back sides reversed, the displacement The output value of the meter B is the displacement meter Q or R in the first signal group. And the shape of the disk to be measured in the diametrical direction are obtained by performing compensation based on the above signal and the signal of the displacement meter R or Q in the second signal group. Of course, this method is also valid when the standard ruler can only be used on one side of the front and back.

  According to a fifth aspect of the present invention, in the measurement apparatus according to any one of the first to fourth aspects, the reference ring has an axial length that is a predetermined ratio or more with respect to a diameter.

  According to a sixth aspect of the present invention, in the invention according to the fourth or fifth aspect, the reference straight ruler has a width equal to or greater than a predetermined ratio with respect to the lengths of the front surface and the back surface.

The measuring apparatus according to claim 7 is a measuring apparatus for measuring a surface shape of an object to be measured.
A rotation axis that is rotatable around the normal of the surface of the object to be measured and is movable in a direction perpendicular to the normal;
A reference ring arranged concentrically with the axis of the rotary shaft and not integrally rotating with the object to be measured but moving integrally with the rotary shaft;
A support arm that is disposed between the object to be measured and the reference ring and is attached to the rotation shaft and rotates;
A first displacement meter A, which is attached to the support arm, detects a displacement in the direction perpendicular to the surface at a point a where the rotation axis of the rotation axis intersects on the surface of the object to be measured, and outputs a first signal. When,
A third displacement meter C that is attached to the support arm and detects a displacement in the direction perpendicular to the surface and outputs a third signal at a point c intersecting with a circle of radius R on the reference ring;
A second displacement meter that measures a displacement at a measurement point different from the points a and c and outputs a measurement signal;
When the measurement is performed while rotating the support arm together with the rotating shaft, the reference value is calculated by using the output value obtained based on the first signal, the measurement signal, and the third signal. The circle is calibrated.
The second displacement meter is attached to the support arm, and detects a displacement in a direction perpendicular to the surface from a point a to a point b having a radius r on the surface of the object to be measured, thereby generating a second signal as a measurement signal. At a point d that intersects with a circle of radius R on the reference ring that is 180 degrees away from point c with respect to the axis of rotation of the axis of rotation. Since the displacement meter D detects the displacement in the vertical direction and outputs a fifth signal as a measurement signal, the surface shape of the object to be measured can be accurately determined using a calibrated reference ring. It can be measured.

  Here, the three-point method is a measurement method for determining the surface shape by measuring the surface of the object to be measured at a plurality of locations using three displacement meters. For example, Makoto Koo and Yoshiyuki Kobayashi: 3 points sequentially Displacement measurement on the circumference applying the method (consideration of measurement principle and measurement error), theory (C) 58, (1992) 1278-1283; Kiyono, Satoshi, Takawei: Software datum by multipoint method and its error Evaluation, Transactions of the Japan Society of Mechanical Engineers (C), 58 (1992), 2262-2267; Toshiharu Ito, Yayoi Narikiyo, Masami Ito: Measurement of planar shape error by two-dimensional least-squares sequential three-point method, Precision Journal 58- 6 (1992), 1023-1028 and the like.

  The measuring apparatus according to an eighth aspect is the invention according to the seventh aspect, wherein the measuring apparatus is attached to the support arm, is on a straight line connecting the point a and the point b on the surface of the object to be measured, and the point a Since the fourth displacement meter E that detects the displacement in the direction perpendicular to the surface at the point e having the radius l and outputs the fourth signal is provided, a more accurate measurement can be performed.

  The measurement standard according to claim 9 is measured by the fourth measuring device, is used for measuring a movement error of rotational scanning and linear scanning, and is a hollow surrounding two plate members orthogonal to each other at the center and the plate member The hollow cylinder has an end surface at a radius r from the axis. It can also be used as a reference sample for Fizeau interferometers.

  The measurement reference according to claim 10 is measured by the fourth measurement device and is used for measuring a movement error in rotational scanning and linear scanning, and includes an inner side surrounding two plate members orthogonal to each other at the center and the plate member A hollow cylinder and an outer hollow cylinder that encloses the inner hollow cylinder, the inner hollow cylinder having an end face at a radius l from the axis, and the outer hollow cylinder having an end face at a radius r from the axis. It is characterized by that. It can also be used as a reference sample for Fizeau interferometers.

  A precision machine tool according to an eleventh aspect includes the measuring device according to any one of the first to eighth aspects. As such a precision machine tool, for example, the one described in JP 2001-353643 A can be used.

  A precision machine tool according to a twelfth aspect has the measurement standard according to the ninth or tenth aspect. As such a precision machine tool, for example, the one described in JP 2001-353643 A can be used.

  Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, a signal from the displacement meter is transmitted to an arithmetic circuit (not shown) for processing. As the displacement meter, a so-called non-contact displacement meter is preferable, but a contact displacement meter that outputs the displacement as an electrical signal by bringing the probe into contact with the object to be measured may be used.

  The principle of the measuring apparatus will be described with reference to FIG. For convenience of explanation, four displacement gauges are shown. The measuring apparatus shown in FIG. 1 supports a disk CP to be measured and rotates with a rotation axis horizontal, and a reference circle that is arranged concentrically with the disk to be measured CP and rotates together with the rotation table RT. A ring SC, a first displacement meter Da that detects a displacement in the direction perpendicular to the surface at a rotation center point a on the surface of the disk CP to be measured, and outputs a first signal; on the surface of the disk CP to be measured; A second displacement meter Db that detects a displacement in the surface vertical direction from a rotation center point a to a point b having a radius r and outputs a second signal, and a line passing through the rotation center point a and the point b is a reference circle SC. A third displacement meter Dc that detects a displacement in the direction perpendicular to the surface and outputs a third signal at a point c that intersects the circle of radius R above, and a point 180 degrees away from the point c with respect to the rotation center point a Displacement in the direction perpendicular to the surface is detected at a point d that intersects the circle of radius R on the reference ring Te has fourth displacement meter and D for outputting a fourth signal. The displacement meters Da to Dd are fixed to a rigid body (not shown). In addition, the reference ring SC is fixed to the rotary table RT by a holding jig HD arranged every 90 degrees.

In the measurement before the first reversal (θ = 0 °) shown in FIG. _1A , the signals output from the four displacement meters Da to Dd are respectively the first signal S _1A (θ) and the second signal. The signal S _1B (θ), the third signal S _1C (θ), and the fourth signal S _1D (θ) are expressed by the following equations (1), (2), (3), and (4). It is done.

Here, φ ₁ (θ), z ₁ (θ), f _r (θ), and g _R (θ) are the inclination of the rotation axis of the rotation table RT in a predetermined direction at the rotation angle θ, and the rotation center point a. , Axial displacement on the circle of radius r of the disk surface to be measured, that is, uneven shape (straight shape), and axial displacement on the circle of radius R of the reference ring SC, that is, uneven shape ( (Straight shape).

Next, as shown in FIG. 1B, when the measurement is performed after rotating the rotary table by 180 degrees (θ = 180 °), the influence of the inclination of the end surface of the reference ring SC added by the inversion is affected. As C, the outputs of the three displacement meters Da, Db, and Dd are expressed as a first signal S _2A (θ), a second signal S _2B (θ), and a fourth signal S _2C (θ), respectively. , (5), (6), and (7).

Here, φ ₂ (θ) and z ₂ (θ) represent the inclination of the rotation axis at the time of the second measurement and the axial displacement of the rotation center point a, respectively. Csin (θ) indicates a change in inclination when the reference ring SC is inverted, but is negligible when considering the shape, and is set to 0 here.

If the difference between Expression (2) and Expression (6) and the difference between Expression (3) and Expression (8) are arranged, Expressions (9) and (10) are obtained. From both expressions, φ ₁ (θ), φ ₂ It can be seen that (θ) can be expressed only by the outputs of the three displacement meters during two rotations before and after inversion. In other words, when measurement is performed while rotating the turntable RT, the output value obtained based on the second signal is compensated based on the first signal, the third signal, and the fourth signal. By doing so, the inclination of the rotation axis and the axial displacement of the rotation center point a can be canceled, and the shape of the position of the radius r on the surface of the disk CP to be measured can be accurately obtained. Only the outputs of the first and third or fourth displacement meters require the repeatability of the tilt motion, but this embodiment makes it unnecessary and improves the measurement accuracy.

Therefore, the concavo-convex shape on the circle of radius r of the disk to be measured CP can be obtained from the displacement meter output only by the equation (11). This is the principle of the method for measuring the concavo-convex shape along the circle of radius r of the disk CP to be measured described in claim 1. From the above data, the shape of the reference ring g _R (θ) can also be identified at the same time. If necessary, the shape of the reference ring is then used as a reference and used together with the data of the third signal and the first signal to calculate the radius. It is possible to specify f _r (θ) with different values.

  Although the figure shows a case where four displacement meters Da to Dd are used, the displacement meters Dc and Dd do not have to be used at the same time. Therefore, when the rotary table RT is rotated, the displacement meter Dc is also 180 at the same time. By changing the position, it can be used as a common displacement meter, and the cost can be reduced by omitting the displacement meter Dd.

As shown in FIG. 1, when the rotation axis is arranged along the horizontal direction, the disk CP to be measured and the reference ring SC are hardly affected by the deflection due to gravity, but the axis is arranged in the vertical direction. Then, since it receives the influence of the deflection | deviation by gravity, Formula (1)-(3), (5), (6), (8) is represented like Formula (12)-(17). The term δ (θ) in the equations (14) and (17) represents a deflection shape due to a change in support before and after the reference ring SC is reversed, and is ignored when the rotation axis is arranged on a horizontal plane. It has been done. In addition, although the measured disc CP is deflected due to gravity, it can be considered that there is no shape change in the disc before and after the reversal of the reference circle SC, and therefore, _fr (θ) includes the deflection shape. It is supposed to be.

However, as can be seen from Equation (19), if the flexure surface shape of the reference ring SC before and after inversion changes, φ ₁ (θ) and φ ₂ (θ) cannot be expressed only by the outputs of the three displacement meters. I understand that. This is not only a deflection due to gravity but also a deflection caused by a force applied when the reference ring SC is attached, so that the holding jig for supporting the reference ring SC as described in claim 1 has the same effect. The HD needs to be devised to suppress deformation due to deflection of the shape g _R (θ) at the end face.

  On the other hand, as shown in FIG. 2, when the object to be measured is cylindrical, the reference ring SC is elongated and hollow, and the rotation axis of the rotary table RT is along the vertical direction, the deflection due to gravity is reduced. The influence is reduced, and there is no need to use a special holding jig. However, in such a case, it is preferable that the reference ring SC is elongated and, for example, the axial length thereof is not less than a predetermined ratio (for example, 1) with respect to its diameter.

In the straightness measurement along the straight line (diameter) represented by the coordinate x, not around the circle, the deflection due to the influence of gravity is reversed before and after the reversal, with respect to the shape of the standard straight ruler. The displacement meter output is given by the following equation. Wherein _{z 1 (x), f x} (x), g x (x), δ 1x (x), δ 2x (x) , respectively, error in the movement in the height direction during the scan along the x, the It is the straight shape of one diameter direction of the measurement disk, the straight shape error of the reference straight ruler, and the deflection shape before and after the reference straight ruler is inverted.

となり，反転前後の基準直定規のたわみが同じでも，その影響を免れないことになる。このため，重力や，あるいは支持力による変形の影響が，測定対象面でのたわみに生じにくい構造の基準直定規を用いる必要がある。

Therefore, even if the deflection of the standard straight ruler before and after reversal is the same, the effect is unavoidable. For this reason, it is necessary to use a standard straight ruler having a structure in which the influence of deformation due to gravity or supporting force is unlikely to occur on the measurement target surface.

  According to the present embodiment, when the irregularities along the circle of radius r on the surface are measured by the rotational scanning of the displacement meter Db, the displacement meter Da for detecting the entering and exiting in the axial direction during rotation, the displacement meter Da, A total of four displacement gauges Dc and displacement gauges Dd for scanning measurement along a circle of radius R on the diameter connecting the measurement points of displacement gauge Db are prepared, and the surface on which the circle of radius R is drawn is the rotational scanning axis Concentric with the circle r of the radius r, the shape is on the reference ring SC that can be reversed and installed at a position rotated 180 degrees relative to the circle of the radius r. By selecting and using a total of six from the output of the displacement meter, the rotational motion error for scanning and the uneven shape along the circle with radius r and the circle with radius R are separated and identified. When the uneven shape along the circle obtained as a result of this and the uneven shape along the straight line obtained on a plurality of diameters using another method are mathematically combined, the plane can be correctly configured.

  Next, a measuring apparatus according to another embodiment will be described. In FIG. 3, the disk to be measured CP is attached to a rotary table (not shown) and is rotatable. A prismatic reference straight ruler SL is arranged in parallel to the surface of the disk CP to be measured. A support member SM as a movable stage is movably disposed along the reference straight ruler SL. The support member SM includes a displacement meter (second displacement meter) Db that measures the displacement of the surface of the disk CP to be measured, a displacement meter Dq that measures one surface (surface) SM1 of the reference straight ruler SL, A displacement meter Dr for measuring the opposing surface (back surface) SM2 of the reference straight ruler SL is attached. When the support member SM moves along the reference straight ruler SL, the displacement meter Db can measure axial displacement on a straight line passing through the rotation axis of the disk CP to be measured.

First, in the state shown in FIG. 3A, when the rotation axis of the disk CP to be measured is the origin and the distance from this is x, the three displacement meters Db to Dr are moved while moving the moving member SM. When the output signals (first signal group) are expressed as signal m ₁ (x), signal m ₂ (x), and signal m ₃ (x), respectively, the following equations (26), (27), ( 28).

Subsequently, as shown in FIG. 3B, the reference straight ruler SL is rotated by 180 degrees. Accordingly, since the front and back surfaces of the reference straight ruler SL are reversed, one surface SM1 is measured by the displacement meter Dr, and the opposite surface SM2 of the reference straight ruler SL is measured by the displacement meter Dr. In this state, the signals (second signal group) output from the three displacement meters Db to Dr while moving the moving member SM are signal m ₁ (x), signal m ₂ (x), and signal m _{3, respectively.} When expressed as (x), the following expressions (29), (30), and (31) are given.

  Here, the following equations (32) and (33) are obtained by calculating the difference between the signals. As a result, the motion error can be canceled and the shape of the disk CP to be measured can be accurately measured in the diameter direction.

  In the above, an example of measuring the straight shape along the standard straight ruler and the disc diameter using the well-known improved inversion method has been shown, but as described above, along the circle on the disc surface Since the shape can also be obtained with the required radius r, combining this result with a straight shape along two or more diameters, the surface shape of the disk can be calibrated.

  Note that the deflection of the reference straight ruler SL has a considerable influence on the measurement accuracy. Therefore, when it is necessary to arrange the measurement surface in a shape that is affected by the deflection due to gravity, as shown in FIG. 4, the width relative to the length L of the front surface and the back surface is supported so as to be rotatable with respect to the rigid body. The measurement accuracy is further improved by measuring the side edge of the reference straight ruler SL with the displacement meters Dq and Dr using the reference straight ruler SL having W equal to or higher than a predetermined ratio (for example, 1: 1). The movable displacement meter Db shown in FIG. 3 can be replaced with the displacement meter Db shown in FIG. That is, it is preferable to combine with a vertical disk as shown in FIG. It may be used in combination with a disk surface placed on a horizontal plane.

  Next, a measuring apparatus according to still another embodiment will be described. In FIG. 5, the support arm SA is fixed to the lower end of the rotation axis RS that rotates about the axis along the normal line on the measurement target plate P having a large area. A reference ring SC is arranged around the rotation axis RS coaxially therewith. The rotation axis RS and the reference ring SC are placed on a stage (not shown) and can move in a direction along the surface of the plate to be measured P. Does not rotate.

  Further, each of the four displacement meters attached to the support arm SA detects a displacement in the surface vertical direction at a point a on the surface of the measurement surface P where the rotation axis of the rotation axis RS intersects. A first displacement meter Da for outputting a signal, and a second displacement meter for detecting a displacement in a surface vertical direction from a point a to a point b having a radius r on the surface of the surface P to be measured and outputting a second signal. A displacement in the direction perpendicular to the surface at a point e having a radius l from the point a on the surface L of the surface to be measured Pb and on the surface L of the surface P to be measured is output. A fourth displacement meter De and a third displacement meter Dc that detects a displacement in the direction perpendicular to the surface and outputs a third signal at a point c intersecting with a circle of radius R on the reference ring SC are provided. It has been. Here, using the first signal, the second signal, and the third signal, the reference ring SC can be calibrated as in the above-described embodiment. Instead of the second displacement meter Db, the displacement in the direction perpendicular to the surface is detected at a point d that intersects a circle with a radius R on the reference ring SC that is shifted 180 degrees from the point c with respect to the rotation axis of the rotation axis RS. A fifth displacement meter Dd that detects and outputs a fifth signal can be provided. In such a case, the inclination of the reference ring SC can be obtained from the difference between the fifth signal and the third signal from the displacement meter Dc, that is, calibration can be performed.

  Similar to the above-described embodiment, when measurement is performed using the calibrated reference ring SC while rotating the rotation axis RS, an output value obtained based on the second signal and the fourth signal is obtained. Is compensated based on the first signal and the third signal, the circular shape at the position of the radius l or r on the surface of the measurement surface P can be obtained. Furthermore, when the measurement is performed while moving the support arm SA along the straight line L connecting the points a and b, the first signal, the second signal, and the fourth signal are used. By using the above-described three-point method, the shape on the straight line L of the surface of the measurement surface P can be obtained. However, in the three-point method in the present embodiment, since the circle of radius R and the height of the three points at the center are associated as the circular shape, the shape height of these three points is determined by three displacement meters. By treating it as an output, the same output as the three-point method can be obtained. By using these, the error can be canceled in the same manner as the equations (26) to (31).

  In this way, by measuring while moving the measuring device over the surface to be measured, the circular shape at the position of the radius l or r of the surface of the surface to be measured P and the shape of the straight line L in the diameter direction thereof. Therefore, as shown in FIG. 6, it is theoretically possible to accurately measure the shape of any large area by superimposing a plurality of circles and straight lines.

  7 and 8 are perspective views showing other examples of the measurement standard MS. 7 includes two plate materials P1 and P2 crossed so as to be orthogonal to each other at the center, and a hollow cylinder CL surrounding the plate materials P1 and P2. The hollow cylinder CL has a radius r from its axis. It has an end face at the position.

  Further, in the measurement standard MS of FIG. 8, two plate materials P1, P2 crossed so as to be orthogonal to each other at the center, an inner hollow cylinder CL1 surrounding the plate materials P1, P2, and an outer side containing the inner hollow cylinder CL1. The inner hollow cylinder CL1 has an end face at a radius 1 from the axis, and the outer hollow cylinder CL2 has an end face at a radius r from the axis.

  The zero point adjustment of the displacement meters Da, Db, De may be performed in the measurement apparatus of FIG. 5 using the measurement standard of FIGS.

  Such a measurement standard MS can be used for calibration of the Fizeau interferometer. Here, the plate material having the measurement surface P is formed of a light transmitting material such as acrylic. The end face of the measurement standard MS is calibrated in advance as described above. In the Fizeau interferometer shown in FIG. 9, the light emitted radially from the point light source OS is irradiated as parallel light by the lens LS, and the reflected light from the measured surface P and after passing through the measured surface P By using the reflected light from the end face of the measurement reference MS, an interference fringe of equal thickness composed of thin multi-beams can be formed, and the shape of the measurement surface P can be obtained from the interference fringe.

  The measurement apparatus and measurement standard described above can be used for various precision machine tools. In machine tools that process precision planes and spheres, either or both of the reference ring and the reference straight ruler are built in, or have a structure to attach them as necessary, so that the work surface of the workpiece or The shaft end surface that fixes the workpiece and the workpiece attachment surface that rotates integrally with the workpiece are structured so that it can be measured as a disk to be measured. From the above measurement results, the machining surface, shaft end surface, and workpiece attachment surface It is possible to check the accuracy of the machine tool or the motion accuracy of the machine tool.

  Furthermore, in machine tools that process precision planes and spherical surfaces, built-in measurement standards that can be used for measurement, as well as calibrated auxiliary wheels and standard straight rulers, or as measurement standards when necessary Workable surface of work piece, shaft end face to fix work piece, or work piece that rotates together with work piece with calibrated auxiliary wheel that can be used and jig part to which standard straight ruler can be attached and detached The mounting surface shape accuracy or machine tool motion accuracy can be measured.

It is a perspective view which shows the principle of the measuring apparatus concerning 1st Embodiment. It is a perspective view which shows the measuring apparatus concerning the modification of this Embodiment. It is a perspective view which shows the principle of the measuring apparatus concerning 2nd Embodiment, and is a figure which shows the principle of the improved inversion method for the measurement of a linear shape, This is a straight shape measurement along the circumference of FIG. By combining with an apparatus, it becomes a planar shape measuring apparatus. Further, a device that is rotated 90 degrees so that a linear shape in a horizontal plane can be measured can be used as a measuring device. However, in that case, it is preferable to use a reference ring having a sufficiently high plate height. It is a figure which shows the modification of reference | standard straight ruler SL. It is a perspective view which shows the principle of the measuring apparatus concerning 3rd Embodiment. It is a figure which shows an example of the locus | trajectory of a circumference when measuring the straightness along a circumference sequentially on the large plane made into the measuring object of the measuring device of FIG. Is formed. It is a perspective view which shows the example of the measurement reference | standard MS used for the measuring apparatus of this Embodiment. It is a perspective view which shows the example of the measurement reference | standard MS used for the measuring apparatus of this Embodiment. It is a perspective view which shows the example of the Fizeau interferometer using the measurement reference | standard of this Embodiment.

Explanation of symbols

CL hollow cylinder CL1 inner hollow cylinder CL2 outer hollow cylinder CP disk to be measured Da displacement meter Db displacement meter Dc displacement meter Dd displacement meter De displacement meter Dq displacement meter Dr displacement meter HD holding jig LS lens L linear MS measurement reference OS point Light source P1, P2 Plate material RS Rotating shaft RT Rotating table SA Support arm SC Reference ring SL Reference straight ruler SM Support member

Claims (12)

In the measuring device that measures the surface shape of the disk to be measured,
A rotating table that supports and rotates the disk to be measured;
A reference ring arranged concentrically with the disk to be measured and rotating together with the rotary table;
A first displacement meter A that detects a displacement in a surface vertical direction at a rotation center point a on the surface of the disk to be measured and outputs a first signal;
A second displacement meter B for detecting a displacement in a direction perpendicular to the surface from a rotation center point a to a point b having a radius r on the surface of the disk to be measured, and outputting a second signal;
A third displacement meter C for detecting a displacement in the direction perpendicular to the surface and outputting a third signal at a point c where a line passing through the rotation center points a and b intersects a circle of radius R on the reference ring; ,
A fourth displacement that detects a displacement in the direction perpendicular to the surface and outputs a fourth signal at a point d that intersects with a circle of radius R on the reference ring that is shifted from the point c by 180 degrees with respect to the rotation center point a. A total of D and
When the measurement is performed while rotating the rotary table, the output value obtained based on the first signal, the second signal, and the third signal is used as the first group data, When the measurement is performed while reversing 180 degrees and rotating the rotary table, an output value obtained based on the first signal, the second signal, and the fourth signal is used as the second data group. As a measuring device, the rotational motion error of the shaft and the radius r and the surface shape along the radius R are obtained from the calculation using both data groups.   When a common displacement meter is used as the third displacement meter C and the fourth displacement meter D, the common displacement meter is used when the disk to be measured and the reference ring are arranged in a predetermined phase. The signal output from the common displacement meter is the fourth signal when the measured disk and the reference ring are shifted 180 degrees from a predetermined phase. The measurement apparatus according to claim 1, wherein the measurement apparatus is a signal.   A stage for moving the second displacement meter B in the diameter direction of the disk to be measured, and the reference being configured while moving the second displacement meter B in the diameter direction of the disk to be measured by the stage; Using a circle, two of the first, third and fourth signals are used to correct the rotational motion error contained in the second signal, and the second signal 3. The measuring apparatus according to claim 1, wherein shape data at a desired radius r is obtained.   A reference straight ruler having a surface facing the disk to be measured and a back surface on the back side thereof is arranged in parallel with the disk to be measured, and the reference straight ruler is mounted on the stage on which the displacement meter B is mounted. A displacement meter Q for detecting the displacement in the vertical direction of the surface and a displacement meter R for detecting the displacement in the vertical direction on the back surface of the reference straight ruler, and moving the stage in the diameter direction of the disk to be measured, The signals output from the three displacement gauges B, Q, and R are used as the first signal group, and then the stage is moved in the diameter direction of the disk to be measured with the front and back surfaces of the reference straight ruler reversed. When the signals output from the three displacement meters B, Q, and R are used as the second signal group, the output value of the displacement meter P is changed to the displacement meter Q or the first signal group. R signal and the displacement meter R or Q signal in the second signal group The measuring apparatus according by compensating, in claim 3, wherein the determination of the diameter direction of the profile of the measurement disc based on.   The measuring apparatus according to claim 1, wherein the reference ring has an axial length that is equal to or greater than a predetermined ratio with respect to a diameter.   The measuring apparatus according to claim 4 or 5, wherein the reference straight ruler has a width equal to or greater than a predetermined ratio with respect to the length of the front surface and the back surface. In a measuring device that measures the surface shape of an object to be measured,
A rotation axis that is rotatable around the normal of the surface of the object to be measured and is movable in a direction perpendicular to the normal;
A reference ring arranged concentrically with the axis of the rotary shaft and not integrally rotating with the object to be measured but moving integrally with the rotary shaft;
A support arm that is disposed between the object to be measured and the reference ring and is attached to the rotation shaft and rotates;
A first displacement meter A, which is attached to the support arm, detects a displacement in the direction perpendicular to the surface at a point a where the rotation axis of the rotation axis intersects on the surface of the object to be measured, and outputs a first signal. When,
A third displacement meter C that is attached to the support arm and detects a displacement in the direction perpendicular to the surface and outputs a third signal at a point c intersecting with a circle of radius R on the reference ring;
A second displacement meter that measures a displacement at a measurement point different from the points a and c and outputs a measurement signal;
When the measurement is performed while rotating the support arm together with the rotating shaft, the reference value is calculated by using the output value obtained based on the first signal, the measurement signal, and the third signal. The circle is calibrated.
The second displacement meter is attached to the support arm, and detects a displacement in a direction perpendicular to the surface from a point a to a point b having a radius r on the surface of the object to be measured, thereby generating a second signal as a measurement signal. At a point d that intersects with a circle of radius R on the reference ring that is 180 degrees away from point c with respect to the axis of rotation of the axis of rotation. A measuring device which is a displacement meter D which detects a displacement in the vertical direction and outputs a fifth signal as a measurement signal.   It is attached to the support arm, detects a displacement in a direction perpendicular to the surface at a point e having a radius l from the point a on the surface of the object to be measured, on a straight line connecting the point a and the point b. The measuring apparatus according to claim 7, further comprising a fourth displacement meter E that outputs a signal.   The measuring apparatus according to claim 4, comprising two plate members orthogonal to each other at the center and a hollow cylinder surrounding the plate member, the hollow cylinder having an end surface at a radius r from the axis. A calibrated metric characterized in that it is used for comparative measurements.   It consists of two plate members orthogonal to each other at the center, an inner hollow cylinder that surrounds the plate member, and an outer hollow cylinder that encloses the inner hollow cylinder, and the inner hollow cylinder has an end face at a radius 1 from the axis. 5. The measurement standard calibrated by the measurement apparatus according to claim 4, wherein the outer hollow cylinder has an end face at a radius r from the axis.   A precision machine tool comprising the measuring device according to claim 1.   A precision machine tool having the measurement standard according to claim 9 or 10.

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