JP2012093236A - Mounting table, shape measuring device, and shape measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting table capable of correcting a position of a revolving shaft easily without changing a compensation table determined beforehand, and to provide a shape measuring device and a shape measuring method.SOLUTION: A mounting table comprises: a mounting part whose mounting surface on which a specimen is placed is rotatable around at least one axis; a base part which supports the mounting part; and a reference part which is fixed to the base part and regulates the position of the mounting surface.

Description

  The present invention relates to a mounting table, a shape measuring device, and a shape measuring method.

  In general, in a shape measuring apparatus that measures the shape of a test object in three dimensions, the orientation of the test object can be rotated or tilted using a mounting table placed on a surface plate, in any direction. The measurement from is to be performed. Such a mounting table is provided with a table having two rotation axes and an inclination axis in order to rotate or tilt the test object (for example, see Patent Document 1).

  By the way, in such a mounting table, the rotation axis of the table slightly shifts due to the weight of the table itself or the deviation of the center of gravity position, and a minute error occurs in the position of the mounting surface on which the test object is mounted. is there. Therefore, in order to accurately measure the shape of the test object, it is necessary to calculate a correction table for correcting the position of the rotation axis of the table over a long time.

JP 2010-160084 A

  However, since the correction table described above is calculated on the assumption that the mounting table is arranged at a predetermined position on the surface plate, for example, the position of the mounting table re-installed on the surface plate after maintenance work or assembly work However, there is a problem that it is necessary to recalculate the correction table again only by slightly deviating.

  The present invention has been made to solve the above problems, and a mounting table, a shape measuring apparatus, and a shape measuring method capable of easily correcting the position of a rotating shaft without changing a previously calculated correction table. The purpose is to provide.

  According to the first aspect of the present invention, the mounting unit having a mounting surface for mounting the test object, and the mounting unit held in a state in which the mounting surface can be rotated with reference to at least one axis. There is provided a mounting table including a base portion that is fixed to the base portion and a reference portion that defines the position of the mounting plate.

  According to the second aspect of the present invention, the mounting table, a light irradiation unit that irradiates the test object mounted on the mounting surface with line light, and a direction different from the irradiation direction of the line light. And a sensor unit having a detection unit for detecting the line light irradiated on the test object.

  According to the third aspect of the present invention, there is provided a method for measuring the shape of the test object on the mounting table arranged on the surface plate, the step of obtaining the position information of the mounting portion with respect to the surface plate, A step of calculating a first correction value by correcting the measurement coordinate value of the test object so as to eliminate a deviation amount with respect to the reference axis in the rotation axis of the mounting portion calculated based on the position information; A step of calculating the second correction value by correcting the first correction value using a correction function table corresponding to the shift, and the rotation axis of the mounting portion with respect to the reference axis. A shape measuring method comprising: correcting the second correction value so as to shift by an amount to calculate a third correction value; and calculating the shape of the test object using the third correction value. Provided.

  According to the present invention, the position correction of the rotation axis can be easily performed without changing the correction table calculated in advance.

The perspective view which shows the structure of a shape measuring apparatus. The side view which shows the structure of a shape measuring apparatus. Explanatory drawing of the calculation method of a correction table. Explanatory drawing of the process of measuring the distance between a reference sphere and each reference member. The figure which shows the concept of a correction table. The flowchart which shows the process of a shape measuring method. The figure which shows the state of the shift | offset | difference of a rotating shaft.

  Hereinafter, a configuration according to an embodiment of the shape measuring apparatus of the present invention will be described with reference to the drawings. In addition, this embodiment is specifically described in order to make the gist of the invention better understood, and does not limit the present invention unless otherwise specified. In addition, in the drawings used in the following description, in order to make the characteristics easy to understand, there is a case where a main part is shown in an enlarged manner for the sake of convenience. Is not limited.

FIG. 1 is a perspective view showing a configuration example of an embodiment according to the shape measuring apparatus of the present invention, and FIG. 2 is a side view.
As shown in FIGS. 1 and 2, the shape measuring apparatus 100 includes a main body 11, an inclined rotary table 14 for placing the test object 200, and a measurement probe 20 for measuring the shape of the test object 200. And a moving unit 30 that moves the measurement probe 20.

  The main body 11 includes a gantry 12 and a surface plate 13 placed on the gantry 12. The gantry 12 is for adjusting the level of the entire shape measuring apparatus 100. The surface plate 13 is made of stone or cast iron, and its upper surface is kept horizontal by the gantry 12. An inclined rotary table 14 is placed on the upper surface of the surface plate 13. The surface plate 13 is provided with a reference sphere 55 for defining a reference (reference coordinates) on the surface plate 13. The reference sphere 55 is fixed to the surface plate 13 so as not to move relative to the surface plate 13, and defines a reference point in the XYZ space formed on the surface plate 13.

  Hereinafter, the configuration of the shape measuring apparatus 100 will be described using an XYZ coordinate system defined by three directions orthogonal to each other. Here, the XY plane defines the upper surface (surface perpendicular to gravity) of the surface plate 13. That is, the X direction defines one direction on the surface plate 13, the Y direction defines a direction orthogonal to the X direction on the upper surface of the surface plate 13, and the Z direction refers to the surface plate 13. The direction (gravity direction) orthogonal to the upper surface of the film is defined.

  The tilted rotary table 14 rotates (rotates) around a rotary table 21 on which the test object 200 is placed, and a rotation axis L1 perpendicular to the upper surface (placement surface) of the rotary table 21. ) The tilting table 22 that can be mounted, the support units 23 and 24 that support the tilting table 22 so that the tilting table 22 can rotate (tilt) about the tilting axis L2 orthogonal to the rotation axis L1, and the support units 23 and 24. The base part 25 is configured. The turntable 21 is a circular plate-like member, and the flatness of the upper surface is regulated with high accuracy. In addition, the base portion 25 is defined with high accuracy on both sides.

  Three position defining members 50 for defining the position of the rotary table 21 are attached to the base portion 25. The position defining member 50 includes three spherical members 50a and a support portion 50b that supports each spherical member 50a. The support part 50 b is set to a length that positions the spherical member 50 a above the upper surface of the turntable 21. With this configuration, when the measurement probe 20 is brought into contact with the spherical member 50a as described later, the amount of movement of the measurement probe 20 is reduced.

  Thereby, the position defining member 50 defines a predetermined surface on the surface plate 13. Further, since the position defining member 50 is fixed to the base portion 25 of the tilt turntable 14, the position of the tilt turntable 14 with respect to the surface plate 13 can be defined.

  The tilt table 22 incorporates a rotary shaft drive motor 22a, and the rotary shaft drive motor 22a rotates the rotary table 21 around the rotary shaft L1. The turntable 21 is connected to the shaft of the rotary shaft drive motor 22a by a plurality of bolts through a plurality of through holes (not shown) formed in the central portion. Note that the rotation angle of the rotary shaft drive motor 22a is measured by an encoder (not shown).

  Moreover, the support part 23 incorporates the inclination axis drive motor 23a, and the inclination axis drive motor 23a rotates the inclination table 22 around the inclination axis L2, thereby making the rotation table 21 predetermined with respect to the horizontal plane. Tilt at a tilt angle of. Note that the tilt angle of the tilt shaft drive motor 23a is measured by an encoder (not shown).

  As described above, in the tilt rotary table 14, the test object placed on the rotary table 21 can be held in an arbitrary posture by rotating the rotary table 21 and tilting the tilt table 22. The rotary table 21 is configured so that the test object can be fixed so that the test object does not shift even when the tilt angle of the tilt table 22 becomes steep.

  By the way, in the tilting rotary table 14, the position of the mounting surface on which the test object 200 is placed by the rotational axis of the rotary table 21 being deviated from the reference (design reference axis) due to the weight of the table itself or the deviation of the center of gravity. Minor errors may occur. In such a state where the rotational axis is displaced, a measurement error occurs because the shape measurement value of the test object 200 includes the amount of change due to the displacement. Therefore, the shape measuring apparatus 100 of the present embodiment corrects the error of the rotary table 21 using a correction table described later, and can accurately measure the shape of the test object 200.

  The measurement probe 20 can acquire the position coordinates of the surface of the test object 200 by contacting the surface of the test object 200. The measurement probe 20 is connected to a control unit 500 for controlling the entire drive of the shape measuring apparatus 100. The controller 500 is connected to the rotary shaft drive motor 22a and the tilt shaft drive motor 23a. The control unit 500 includes an arithmetic processing unit 300 that performs processing for the measurement coordinates of the test object 200 detected by the measurement probe 20 and processing for the angles of the rotary shaft drive motor 22a and the tilt shaft drive motor 23a. Yes.

  The moving unit 30 is for scanning the state where the tip of the measurement probe 20 is in contact with the surface of the test object 200. In the shape measuring apparatus 100 according to the present embodiment, the measurement probe 20 is moved by the moving unit 30 in the direction specified by the shape measurer as described later.

  The moving unit 30 is mainly composed of a portal frame 15. Note that the surface plate 13 is configured such that an end portion (right end portion in FIG. 2) also serves as a Y-axis guide that drives the portal frame 15 on the surface plate 13 in the Y-axis direction.

  The portal frame 15 includes an X-axis guide 15a extending in the X-axis direction, a driving side column 15b driven along the Y-axis guide of the surface plate 13, and a follower that slides on the upper surface of the surface plate 13 according to the driving of the driving side column 15b. It is comprised by the side pillar 15c.

  The head portion 16 can be driven along the X-axis direction along the X-axis guide 15 a of the portal frame 15. A Z-axis guide 17 that can be driven in the Z-axis direction with respect to the head unit 16 is attached to the head unit 16. The measurement probe 20 is attached to the lower end portion of the Z-axis guide 17, and the measurement probe 20 is configured to be rotatable about the Z-axis and tiltable about a predetermined axis in the horizontal direction. .

  As described above, the shape measuring apparatus 100 freely moves the measurement probe 20 in each of the X direction, the Y direction, and the Z direction by driving the portal frame 15, the head unit 16, and the Z axis guide 17. The tip of the measurement probe 20 can be directed in an arbitrary direction by rotating and tilting the measurement probe 20.

  Hereinafter, the shape measuring method according to the present invention will be described together with the description of the operation of the shape measuring apparatus 100. The shape measuring apparatus 100 uses the correction table to correct the deviation between the rotation axis L1 and the inclination axis L2 of the tilt rotation table 14 (rotation table 21), and can accurately measure the shape of the test object 200. Yes.

  Here, before explaining the shape measurement method, an example of a correction table calculation method used as a premise of shape measurement will be described with reference to FIG. The correction table is performed after the tilt rotation table 14 is first installed on the surface plate 13.

  First, the rotation axis L1 of the turntable 21 is aligned with the Z direction on the surface plate 13, and the inclination rotation table 14 is adjusted on the surface plate 13 so that the inclination axis L2 of the rotation table 21 is aligned with the X direction on the surface plate 13. Install in place.

  Then, as shown in FIG. 3, the rotary table 21 in which a plurality of reference members 40 are arranged along the outer peripheral edge of the upper surface is inclined by a predetermined angle about the rotation axis L1 and is predetermined about the rotation axis L1. Rotate only the angle. As a result, the center axis C1 of the rotary table 21 is shifted.

  Thereafter, each position of the reference member 40 is measured by the measurement probe 20 to measure the center coordinates of the circle defined by the reference member 40. In addition, since the reference member 40 is disposed at a predetermined distance from the upper surface of the turntable 21, the actual measurement coordinates of the turntable 21 can be measured based on the above-described center coordinates. Similarly, the coordinate values (actually measured values) of the rotary table 21 at various positions are measured by varying the rotation amount or the tilt amount around the rotation axis L1 and the tilt axis L2.

  By the way, the shape measuring apparatus 100 according to the present embodiment measures the position of the reference member 40 using the reference sphere 55 provided on the surface plate 13. Specifically, as shown in FIG. 4, the distance between the reference sphere 55 and each reference member 40 is measured by the measurement probe 20, the coordinates of each reference member 40 are measured, and the center coordinates are measured. ing.

  According to this configuration, the position of each position defining member 50 is measured by the distance from the reference sphere 55 that is securely fixed to the surface plate 13, so that the error component of the moving unit 30 that holds the measurement probe 20 is the position defining. Influencing the position coordinates of the member 50 is prevented. Therefore, the position coordinates of the position defining member 50 can be obtained with high accuracy, and a highly reliable correction table can be obtained.

  On the other hand, at each position described above, the coordinate values (machine coordinate values) in the rotary table 21 are mechanically calculated from the encoder values of the rotary table 21 (the rotary shaft drive motor 22a and the tilt shaft drive motor 23a). Then, the actual measurement value and the machine coordinate value are compared for each position of the rotary table 21, and a deviation amount in each is obtained. Note that this deviation amount is caused by the deviation between the rotation axis L1 and the inclination axis L2 of the rotary table 21 caused by the weight of the table itself, the deviation of the center of gravity position, or the like as described above.

FIG. 5 is a diagram illustrating the concept of the correction table.
The correction values (A1, B1) in the correction table are, as shown in FIG. 5, the encoder value of the rotary shaft drive motor 22a that rotates about the rotary shaft L1 is A1, and the inclination that rotates about the rotary shaft L1. When the encoder value of the shaft drive motor 23a is B1, a parameter value for correcting the deviation between the mechanical coordinate value of the rotary table 21 and the measured coordinate value is stored. Such a correction table is stored in a storage unit in the control unit 500.

  Next, a method for measuring the shape of the test object 200 using the correction table will be specifically described. In the following description, for example, when the tilt rotation table 14 is temporarily moved from the surface plate 13 due to maintenance work or the like, the operation of the shape measuring apparatus 100 is resumed when it is installed on the surface plate 13 again. Explained as an example. When the tilt rotation table 14 is re-installed on the surface plate 13 in this way, the position of the tilt rotation table 14 on the surface plate 13 is slightly shifted, so that the above correction table cannot be applied as it is. is there.

  In this embodiment, the shape measurement method based on the flow shown in FIG. 6 can be used in this embodiment to measure the shape of the test object 200 with high accuracy while using the correction table as it is. ing.

  The shape measurer places the test object 200 on the rotary table 21. Prior to measuring the shape of the test object 200, the shape measuring apparatus 100 acquires position information of the tilt rotation table 14 with respect to the surface plate 13 (step S1).

  Specifically, the control unit 500 drives the moving unit 30 to measure each position of the position defining member 50 by moving the measurement probe 20. At this time, the position of the position defining member 50 is measured using a reference sphere 55 provided on the surface plate 13. The distance between the reference sphere 55 and each position defining member 50 is measured by the measurement probe 20, and the position coordinates of each position defining member 50 are measured. Thus, by measuring the position of each position defining member 50 based on the distance from the reference sphere 55, the error component of the moving unit 30 that holds the measurement probe 20 does not affect the position coordinates of the reference member 300. Therefore, the position coordinates of the position defining member 50 can be obtained with high accuracy.

  Subsequently, based on the position information of the position defining member 50, a deviation of the rotation axes L1, L2 of the tilt rotation table 14 from the reference axis (X axis, Z axis) is calculated (step S2). Specifically, since the position defining member 50 is securely fixed to the base portion 25 of the tilt rotation table 14, the control unit 500 determines the rotation axis L 1 and tilt axis of the turn table 21 from the position information of the position defining member 50. The deviation with respect to the X axis and the Z axis in L2 can be calculated.

  FIG. 7 shows a state of deviation between the rotation axes L1 and L2 obtained as a result. FIG. 7 shows a state where the rotation axis L1 of the tilt rotation table 14 is shifted by an angle φ2 with respect to the X axis, and the tilt axis L2 is shifted by an angle φ1 with respect to the Z axis.

  After calculating the deviation between the rotation axis L1 and the inclination axis L2 of the tilt rotation table 14 by the above-described process, the shape measuring apparatus 100 drives the moving unit 30 to bring the tip of the measurement probe 20 into contact with the test object 200. The measurement coordinate value of the surface of the test object 200 is acquired by scanning in a predetermined direction while being transmitted to the arithmetic processing unit 300.

  The shape measuring apparatus 100 measures the shape of the test object 200 with reference to the reference sphere 55 by bringing the measurement probe 20 into contact with the reference sphere 55. In this way, by using the reference sphere 55 securely fixed to the surface plate 13 as a reference, the influence of the positional deviation of the measurement probe 20 due to the environmental change such as temperature and the influence of aging is suppressed, and the shape measurement of the test object 200 is performed. Can be performed with high accuracy. When the measurement probe has a light cutting or SFF probe, the shape of the test object 200 can be measured using the reference sphere 55 as a reference in the same manner as the contact probe. Also in this case, the reference sphere 55 that is securely fixed to the surface plate 13 is used as a reference to suppress the influence of the positional deviation of the measurement probe 20 due to the environmental change such as temperature and the influence of aging, and is the same as the contact type measurement probe. In addition, the shape of the test object 200 can be measured with high accuracy.

  The arithmetic processing unit 300 corrects the measurement coordinate value obtained by measuring the test object 200 so as to eliminate the deviation of the rotation axes L1 and L2 measured in step S2, and calculates the first correction value ( Step S3). Specifically, the measurement coordinate value (for example, (x, y, z)) of the test object 200 is corrected by the amount of deviation (φ1, φ2) between the rotation axes L1, L2 calculated in step S2. Thus, the first correction coordinate value F1 (x ′, y ′, z ′) is calculated.

  Next, the first correction coordinate value is corrected using the correction table and calculated as a second correction coordinate value F2 (step S4). Specifically, in the shape measuring apparatus 100, the control unit 500 acquires the encoder value in the rotation table 21, thereby acquiring the optimum correction parameter from the correction table. Then, based on the correction parameter, the first correction coordinate value F1 is corrected and calculated as the second correction coordinate value F2 (x ″, y ″, z ″). Since the first correction coordinate value F1 is corrected for the deviation of the rotation axes L1, L2, the rotation axes L1,. It is possible to effectively apply the correction table calculated on the assumption that there is no L2 misalignment.

  Next, the second correction coordinate value F3 (x ″, y ″, z ″) is corrected so as to return only the deviation (φ1, φ2) of the rotation axes L1, L2, and the third correction coordinate value F3. (X "", y "", z "") is calculated (step S5).

  The third correction coordinate value F3 calculated in this way is obtained by canceling the correction table in a state where the deviation (φ1, φ2) of the rotation axes L1 and L2 as described above is canceled for the measurement coordinate value of the test object 200. After effective application, this corresponds to a case where the measurement coordinate value is returned again by the deviation (φ1, φ2) of the rotation axes L1, L2. Therefore, it is possible to obtain a measurement value in consideration of correction of the deviation of the rotation axes L1 and L2 of the tilt rotation table 14 (rotation table 21) by the correction table, and to accurately measure the shape of the test object 200.

  According to the tilt rotation table 14 according to the present embodiment, the position on the surface plate 13 can be detected based on the position defining member 50. Further, it is possible to easily detect the amount of deviation between the rotation axes L1 and L2 based on the position defining member 50. Therefore, by using the shape measuring method shown in the above flow, the shape of the test object 200 can be accurately measured without changing the correction table stored in the control unit 500.

  Further, according to the shape measuring apparatus 100 according to the present embodiment, since the tilt rotating table 14 is provided, for example, when the tilt rotating table 14 is removed from the surface plate 13 by maintenance work or the like and then installed again. Even when the position of the tilt rotation table 14 is slightly shifted, the displacement amount of the rotation axes L1 and L2 can be easily detected based on the position defining member 50. Therefore, by using the shape measuring method shown in the above flow, the shape of the test object 200 can be accurately measured without changing the correction table stored in the control unit 500. Further, the position of the tilt rotation table 14 is guaranteed by the measurement accuracy of the measurement probe 20. The shape measuring device is sufficient if the coordinate accuracy of the measurement accuracy of the measuring probe is guaranteed, and a mounting table for shape measurement that does not require an expensive calibration device such as a high-precision laser interferometer can be provided.

  Further, according to the shape measuring method according to the present embodiment, even when the rotational axis shift as described above occurs when the inclined rotary table 14 is rearranged on the surface plate 13, the first correction is performed. By correcting to the coordinate value F1, the second correction coordinate value F2, and the third correction coordinate value F3, the correction table can be used as it is. Therefore, the shape measurement of the test object 200 is not complicated and can be performed in a short time.

  In the above-described embodiment, the tilt rotation table 14 including the rotation table 21 that can rotate around the two axes of the rotation axes L1 and L2 has been described as an example of the mounting table. However, the present invention focuses on at least one axis. As long as the mounting table has a rotatable mounting surface. For example, the present invention can be applied even if the rotary table 21 is configured to be rotatable only on one of the rotation axes L1 and L2.

In the above-described embodiment, the configuration in which three position defining members 50 are provided on the rotary table 21 has been described as an example, but a configuration in which four or more position defining members 50 are provided may be employed.
Further, in the above-described embodiment, the shape measuring apparatus including the contact type measurement probe has been described as an example. However, the present invention is not limited to this, and includes a non-contact type measurement probe using a light cutting method. The present invention can also be applied to other shape measuring apparatuses. Further, the present invention can also be applied to a shape measuring apparatus provided with each of the contact type and non-contact type measurement probes.

  Moreover, the kind of probe which can be provided in the shape measuring apparatus to which the present invention is applied is not limited to the above-described example.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

L1 ... Rotation axis, L2 ... Tilt axis, F1 ... First correction coordinate value, F2 ... Second correction coordinate value, F3 ... Third correction coordinate value, 13 ... Surface plate, 14 ... Tilt rotation table, 15 ... Gate frame , 20 ... measurement probe, 21 ... rotary table, 50 ... position defining member, 55 ... reference sphere, 100 ... shape measuring device, 200 ... test object

Claims (7)

A mounting portion on which a mounting surface on which the test object is mounted is rotatable about at least one axis;
A base portion for supporting the mounting portion;
A reference portion that is fixed to the base portion and defines the position of the placement surface;
A mounting table.   The mounting table according to claim 1, wherein the reference portion includes at least three spherical members.   The mounting table according to claim 1, wherein the mounting table is capable of rotating around a rotation axis perpendicular to the mounting surface and tilting around an inclination axis perpendicular to the rotation axis. The mounting table according to any one of claims 1 to 3,
A measurement probe for measuring the shape of the test object placed on the placement surface,
A surface plate for placing the mounting table, and
A shape measuring apparatus comprising:   The shape measuring apparatus according to claim 4, wherein the surface plate is provided with a reference member that defines a reference point on the surface plate. A method for measuring the shape of an object on a mounting table placed on a surface plate,
Obtaining the position information of the mounting table with respect to the surface plate, and calculating a deviation of the rotation axis of the mounting table with respect to a reference axis defined on the surface plate based on the position information;
Correcting a measurement coordinate value obtained by measuring the test object so as to eliminate a deviation of the rotation axis, and calculating a first correction value;
Calculating the second correction value by correcting the first correction value using a correction function table set in advance based on the mounting table aligned with the reference axis;
Correcting the second correction value so as to return only the deviation of the rotation axis, and calculating a third correction value;
A shape measuring method including:   The shape measuring method according to claim 6, wherein the position information of the mounting table is acquired using a position defining member that is provided on the mounting table and defines a position of a mounting unit on which the test object is mounted.

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