JP6846673B2 - Angle correction method and angle correction device for surface shape measuring device - Google Patents

Description

The present invention relates to an angle correction method and an angle correction device of a surface shape measuring device that measures the surface shape of a work while rotating the work and the detector relatively.

Conventionally, as a surface shape measuring device for measuring the surface shape of a work, a roundness measuring machine for measuring the roundness of the work or the like has been known (see, for example, Patent Document 1).

This type of surface shape measuring device includes a table on which a work is placed, a detector that detects the surface position of the work, a rotation mechanism that rotates the work relative to the detector about a rotation axis, and a rotation mechanism. It is provided with a rotation angle detection device (for example, a rotary encoder or the like) provided in the above.

Then, in the surface shape measuring device, the surface position of the work is detected by the detector while rotating the work placed on the table relative to the detector, so that the surface position of the work accompanying the rotation of the work ( Measurement data indicating the radial position and the circumferential position) is acquired, and the parameters for evaluating the surface shape of the work are calculated from the measurement data.

Japanese Unexamined Patent Publication No. 2004-108787

By the way, in the conventional surface shape measuring device, an error occurs in the detection angle of the rotation angle detecting device due to an eccentricity error caused by eccentricity when the rotation angle detecting device is attached to the rotating mechanism and a shape error caused by the shape of the rotation angle detecting device. Occurs.

For example, when the rotation angle detection device is attached in an eccentric state with respect to the rotation axis of the rotation mechanism, as shown in FIG. 15, a periodic detection angle having a sinusoidal characteristic of one cycle per rotation. An error occurs.

Further, since the shape of the rotation angle detection device varies, as shown in FIG. 16, a random angle detection error occurs for each rotation angle as an error due to the shape of the rotation angle detection device.

Therefore, in the rotation angle detection device used in the conventional surface shape measurement device, the eccentricity error due to the eccentricity when the rotation angle detection device is attached and the shape error due to the shape of the rotation angle detection device are intricately intertwined. Therefore, since the angle detection error as shown in FIG. 17 occurs, there is a problem that the measurement accuracy of the surface shape of the work cannot be improved.

The present invention has been made in view of such circumstances, and is a surface shape measuring device capable of improving the measurement accuracy of the surface shape of a work without being affected by the detection angle error of the rotation angle detecting device. It is an object of the present invention to provide an angle correction method and an angle correction device.

The following inventions are provided in order to achieve the above object.

The angle correction method of the surface shape measuring device according to the first aspect of the present invention includes a table on which the work is placed, a detector for detecting the surface position of the work, and the work relative to the detector around the rotation axis. It is an angle correction method for correcting the detection angle error of the rotation angle detection device of the surface shape measuring device provided with the rotation mechanism for rotating the rotation mechanism and the rotation angle detection device for detecting the rotation angle of the rotation mechanism. The master work detected by the detector while the center of the placed master work is eccentric by the eccentric distance in the first direction perpendicular to the rotation axis, and the master work is rotated relative to the detector by the rotation mechanism. The first measurement data acquisition step of acquiring the first measurement data in which the surface position of the above is associated with the detection angle of the rotation angle detection device, and the center of the master work placed on the table in the first direction are around the rotation axis. The rotation angle detector detects the surface position of the masterwork detected by the detector while rotating the masterwork relative to the detector by the rotation mechanism in a state where it is eccentric by the eccentric distance in the second direction with different phases. The second measurement data acquisition step of acquiring the second measurement data associated with the angle, and the angle error correction step of correcting the detection angle error of the rotation angle detection device based on the first measurement data and the second measurement data. Be prepared.

In the angle correction method of the surface shape measuring device according to the second aspect of the present invention, in the first aspect, in the angle error correction step, the measurement data of either the first measurement data or the second measurement data is the measurement data of the other. The angle at which the detection angle error of the rotation angle detection device is calculated by comparing the phase correction process that performs phase correction so that there is no phase difference with respect to the other, and one measurement data after phase correction and the other measurement data. It has an error calculation step.

In the angle correction method of the surface shape measuring device according to the third aspect of the present invention, in the second aspect, the angle error calculation step calculates the detection angle error of the rotation angle detection device for each rotation angle.

The angle correction method of the surface shape measuring device according to the fourth aspect of the present invention is in any one of the first to third aspects, and the angle error correction step is based on the detection angle error of the rotation angle detection device. Correct the detection angle of the rotation angle detection device.

The angle correction method of the surface shape measuring device according to the fifth aspect of the present invention is in any one of the first to third aspects, and the angle error correction step is based on the detection angle error of the rotation angle detection device. Correct the surface position of the workpiece detected by the detector.

The angle correction method of the surface shape measuring device according to the sixth aspect of the present invention is any one of the first to fifth aspects, and in the angle error correction step, the detection angle error of the rotation angle detection device is within an allowable range. It is determined whether or not the error is within the permissible range, and if the detection angle error is within the permissible range, no correction is performed, and if the detection angle error exceeds the permissible range, the correction is performed.

The angle correction device of the surface shape measuring device according to the seventh aspect of the present invention includes a table on which the work is placed, a detector for detecting the surface position of the work, and the work relative to the detector around the rotation axis. It is an angle correction device for correcting the detection angle error of the rotation angle detection device of the surface shape measuring device provided with the rotation mechanism for rotating the rotation mechanism and the rotation angle detection device for detecting the rotation angle of the rotation mechanism, and is mounted on the table. The master work detected by the detector while the center of the placed master work is eccentric by the eccentric distance in the first direction perpendicular to the rotation axis, and the master work is rotated relative to the detector by the rotation mechanism. The first measurement data acquisition unit that acquires the first measurement data in which the surface position of the above is associated with the detection angle of the rotation angle detection device, and the center of the master work placed on the table in the first direction are around the rotation axis. The rotation angle detector detects the surface position of the masterwork detected by the detector while rotating the masterwork relative to the detector by the rotation mechanism in a state where it is eccentric by the eccentric distance in the second direction with different phases. A second measurement data acquisition unit that acquires the second measurement data associated with the angle, and an angle error correction unit that corrects the detection angle error of the rotation angle detection device based on the first measurement data and the second measurement data. Be prepared.

In the seventh aspect, the angle correction device of the surface shape measuring device according to the eighth aspect of the present invention rotates the center of the masterwork in a state where the center of the masterwork is eccentric by an eccentric distance from the rotation axis in the first direction. It is equipped with a masterwork moving mechanism that can switch between a state in which the shaft is eccentric by the eccentric distance in the second direction.

According to the present invention, it is possible to improve the measurement accuracy of the surface shape of the work without being affected by the detection angle error of the rotation angle detection device.

Schematic diagram showing the configuration of the roundness measuring machine of this embodiment Functional block diagram showing the configuration of the data processing device Functional block diagram showing the configuration of the angle error correction table creation unit Schematic diagram showing the state when the first measurement is performed The figure which showed an example of the 1st measurement data acquired by the 1st measurement data acquisition part. Schematic diagram showing the state when the second measurement is performed The figure which showed an example of the 2nd measurement data acquired by the 2nd measurement data acquisition part. The figure which showed an example of the difference data between the 1st measurement data and the 2nd measurement correction data. The figure which showed the 1st measurement data and the 2nd measurement data after polar coordinate transformation. The figure for demonstrating the calculation method of the detection angle error The figure which showed an example of the angle error correction table The flowchart which showed the angle correction method using the roundness measuring machine of this embodiment The figure which showed the configuration example of the master work movement mechanism The figure which showed the operation example of the master work movement mechanism The figure which showed an example of the detection angle error (eccentric error) caused by the eccentricity at the time of mounting an encoder scale. The figure which showed the detection angle error (shape error) due to the shape of an encoder scale. The figure which showed an example of the detection angle error which occurs in the conventional surface shape measuring apparatus.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the embodiment described below, a roundness measuring machine is illustrated as an example of a surface shape measuring device to which the present invention is applied, but the present invention provides various types of surface shape measuring for measuring the surface shape of a work. Widely applicable to devices.

(Configuration of roundness measuring machine)
First, the configuration of the roundness measuring machine 10 of the present embodiment will be described with reference to FIG. FIG. 1 is a schematic view showing the configuration of the roundness measuring machine 10 of the present embodiment.

As shown in FIG. 1, the roundness measuring machine 10 of the present embodiment is provided with a rotary table 14 on which a work (measurement object) W is placed on a base (base) 12. The rotary table 14 is finely fed in the X and Y directions by the X-direction fine movement knob 16 and the Y-direction fine movement knob 18, and the X-direction tilt knob (not shown) and the Y-direction tilt knob (not shown) provide the X-direction and the Y-direction fine movement knob. The inclination is adjusted in the Y direction.

The rotary table 14 is rotatably supported by a motor 20 (an example of a rotary mechanism) via a bearing (not shown). A rotation angle detection device 36 (see FIG. 2) is attached to the rotation shaft of the motor 20 so that the rotation angle can be read with high accuracy. The rotation angle detection device 36 is composed of, for example, a rotary encoder or the like. For the bearing, for example, an ultra-high precision static pressure air bearing is used, and the rotary table 14 is rotated with a very high rotation accuracy (for example, 0.005 μm). The rotation angle detection device 36 detects the rotation angle of the work W placed on the rotation table 14 by detecting the rotation angle of the rotation axis of the motor 20. The detection signal (rotation angle data) output from the rotation angle detection device 36 is input to the data processing device 100 described later. The rotation angle detection device 36 is not limited to the rotary encoder, and for example, the rotation angle detection device 36 may detect the rotation angle of the work W based on the information of the drive signal (number of pulses) of the motor 20 that drives the rotary table 14. Good.

A column (post) 22 extending in the vertical direction (Z direction) is erected on the base 12, and a carriage 24 is movably supported in the column 22 in the vertical direction (Z direction). An arm (radial movement axis) 26 is movably supported on the carriage 24 in the horizontal uniaxial direction (X direction). A detector holder 28 is attached to the tip of the arm 26. A detector 30 is attached to the tip of the detector holder 28. An electric micrometer using a differential transformer is used for the detector 30, and the displacement amount of the stylus 32 in contact with the surface of the work W is detected. The detection signal (displacement data) output from the detector 30 is input to the data processing device 100 described later.

The position of the detector 30 (position in the X direction, position in the Z direction) is detected by the detector position detection device 34 (see FIG. 2). The detector position detection device 34 detects the positions of an X-axis linear encoder (not shown) that detects the position of the arm 26 that moves the detector 30 in the X direction and a carriage 24 that moves the detector 30 in the Z direction. It is equipped with a Z-axis linear encoder (not shown). The detection signal (detector position data) output from the detector position detection device 34 is input to the data processing device 100 described later.

When measuring the roundness of the work W with the roundness measuring machine 10 of the present embodiment, after the work W is placed on the rotary table 14, the rotation axis (rotation center) O of the rotary table 14 is first measured. The eccentricity correction with respect to the center of the work W and the inclination correction of the work W with respect to the rotation axis O of the rotary table 14 are performed.

Next, the rotary table 14 is rotated once by the motor 20 in a state where the stylus 32 of the detector 30 is in contact with the surface (side surface) of the work W, and data for one round of the surface of the work W is collected. At this time, the detection signals output from the detector 30, the detector position detection device 34, and the rotation angle detection device 36 are input to the data processing device 100, respectively.

The data processing device 100 generates and generates measurement data in which the radial position (R value) and the circumferential position (θ value) at each measurement point on the surface of the work W are associated with each other based on each input detection signal. The roundness of the work W and the like are calculated based on the measured data. The result of arithmetic processing by the data processing device 100 is displayed on the output unit 110 of a monitor, a printer, or the like.

(Configuration of data processing device)
Next, the configuration of the data processing device 100 will be described. The data processing device 100 is an example of the angle correction device according to the present invention.

FIG. 2 is a functional block diagram showing the configuration of the data processing device 100. The data processing device 100 is realized by a computer and includes a measurement data generation unit 102, an angle error correction table creation unit 104, a measurement data correction unit 106, and a storage unit 108, as shown in FIG. In the figure, each element described as a functional block that performs various processes can be composed of a CPU, a memory, and other LSIs in terms of hardware, and is loaded into the memory in terms of software. It is realized by a program or the like. That is, these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof, and are not limited to any of them.

The measurement data generation unit 102 obtains the radial position (R value) of each measurement point on the surface of the work W from the detection signals (displacement data and detection value position data) output from the detector 30 and the detector position detection device 34. In addition to the calculation, the circumferential position (θ value) of each measurement point is calculated from the detection signal (rotation angle data) output from the rotation angle detection device 36, and the measurement data associated with these is generated. The measurement data generation unit 102 outputs the measurement data thus generated to the measurement data correction unit 106. Further, the measurement data is stored in the storage unit 108 as needed.

The angle error correction table creation unit 104 calculates the detection angle error of the rotation angle detection device 36 and creates an angle error correction table for correcting the detection angle error. The angle error correction table creation unit 104 stores the created angle error correction table in the storage unit 108.

The measurement data correction unit 106 reads the angle error correction table stored in the storage unit 108, and by referring to the angle error correction table, the measurement data generated by the measurement data generation unit 102 when the work W is measured. Correction processing is performed. The measurement data correction unit 106 outputs the corrected measurement data to the output unit 110 of a monitor, printer, or the like. The measurement data correction unit 106 is an example of an angle error correction unit.

FIG. 3 is a functional block diagram showing the configuration of the angle error correction table creating unit 104. As shown in FIG. 3, the angle error correction table creation unit 104 includes a first measurement data acquisition unit 112, a second measurement data acquisition unit 114, a phase correction unit 116, and an angle error calculation unit 118.

The first measurement data acquisition unit 112 acquires the first measurement data when the first measurement is performed using the master work MW (see FIG. 4) having a known diameter.

FIG. 4 is a schematic view showing a state when the first measurement is performed. In the first measurement, as shown in FIG. 4, the center C of the master work MW placed on the rotation table 14 is preset in the first direction (plus direction in the X direction in this example) perpendicular to the rotation axis O. It is assumed that the device is placed at a position (first measurement position) eccentric by the eccentric distance E. Then, with the master work MW arranged at the first measurement position, the stylus 32 of the detector 30 is brought into contact with the surface of the master work MW, and the stylus 30 is rotated by the rotary table 14 while rotating the master work MW. 32 displacements are detected. As a result, the first measurement data acquisition unit 112 has the diameter of each measurement point on the surface of the master work MW based on the detection signals output from the detector 30, the detector position detection device 34, and the rotation angle detection device 36, respectively. The directional position (R value) and the circumferential position (θ value) are calculated, and the first measurement data in which they are associated is acquired.

FIG. 5 is a diagram showing an example of the first measurement data acquired by the first measurement data acquisition unit 112. As shown in FIG. 5, the first measurement data has a circular shape centered on the first measurement position (masterwork center C) eccentric by the eccentric distance E from the rotation axis O in the first direction (plus direction in the X direction). It becomes the measurement data of. The first measurement data acquisition unit 112 outputs the first measurement data to the angle error calculation unit 118.

The second measurement data acquisition unit 114 acquires the second measurement data when the second measurement using the master work MW (see FIG. 6) is performed. The same masterwork MW shall be used for the first measurement and the second measurement.

FIG. 6 is a schematic view showing a state when the second measurement is performed. As shown in FIG. 6, in the second measurement, the center C of the master work MW placed on the rotary table 14 is in the second direction in which the phase around the rotation axis O is different from the first direction (plus direction in the X direction). It is assumed that the device is arranged at a position (second measurement position) eccentric by the eccentric distance E. That is, the second measurement position has a predetermined phase (rotation angle) in a predetermined rotation direction (in this example, the CCW direction (counterclockwise direction)) with the center C of the master work MW as the center of the rotation axis O from the first measurement position. ) This is a position that is out of phase by φ. Then, with the master work MW arranged at the second measurement position, the stylus 32 of the detector 30 is brought into contact with the surface of the master work MW, and the stylus 32 is rotated by the detector 30 while rotating the master work by the rotary table 14. Detects the displacement of. As a result, the second measurement data acquisition unit 114 has the diameter of each measurement point on the surface of the master work MW based on the detection signals output from the detector 30, the detector position detection device 34, and the rotation angle detection device 36, respectively. The directional position (R value) and the circumferential position (θ value) are calculated, and the second measurement data in which they are associated is acquired.

FIG. 7 is a diagram showing an example of the second measurement data acquired by the second measurement data acquisition unit 114. As shown in FIG. 7, the second measurement data is the second measurement position (masterwork center C) eccentric by the eccentric distance E in the second direction (the direction in which the phase is deviated by φ from the first direction) from the rotation axis O. It becomes the second measurement data of the circular shape centered on. The second measurement data acquisition unit 114 outputs the second measurement data to the phase correction unit 116.

The phase correction unit 116 performs a phase correction process for shifting the phase of the input second measurement data by φ in the direction opposite to the rotation direction, that is, in the CW direction (clockwise direction) (an example of the phase correction step). ). As described above, the first measurement data and the second measurement data are phase-corrected because each measurement (first measurement and second measurement) is performed in a state where the phase is shifted by φ around the rotation axis O. In unit 116, the phase correction processing of the second measurement data is performed so that the phase difference between the first measurement data and the second measurement data disappears, so that the first measurement data and the second measurement data after the phase correction processing are combined. The phases match. The phase correction unit 116 outputs the second measurement correction data to which the phase correction processing has been performed to the angle error calculation unit 118. Hereinafter, the second measurement data after the phase correction processing is referred to as "second measurement correction data".

In the present embodiment, the phase correction processing is performed on the second measurement data so that the phase difference between the first measurement data and the second measurement data disappears, but the first measurement data is not limited to this. On the other hand, the phase correction process may be performed.

The angle error calculation unit 118 calculates the detection angle error of the rotation angle detection device 36 for each rotation angle based on the input first measurement data and the second measurement correction data. Then, an angle error correction table showing the detection angle error for each rotation angle is created, and the angle error correction table is stored in the storage unit 108.

(Difference data between the first measurement data and the second measurement correction data)
FIG. 8 is a diagram showing an example of difference data between the first measurement data and the second measurement correction data. Note that FIG. 8 shows the difference data after the polar coordinate conversion, in which the horizontal axis shows the circumferential position θ and the vertical axis shows the error ΔR of the radial position R. Further, the first measurement data and the second measurement data after the polar coordinate conversion are shown in FIG. 9 for reference. In FIG. 9, reference numeral T1 indicates first measurement data, reference numeral T2 indicates second measurement data, and reference numeral T2p indicates second measurement correction data (second measurement data after phase correction processing).

As shown in FIG. 8, in the difference data between the first measurement data and the second measurement correction data, the error ΔR of the radial position R varies depending on the circumferential position θ at each measurement point on the surface of the work W. To do. This error ΔR represents a shape error component generated due to the detection angle error of the rotation angle detection device 36. The difference data shown in FIG. 8 corresponds to the difference data between the first measurement data T1 and the second measurement correction data T2p shown in FIG.

Here, in the present embodiment, the first measurement data and the second measurement data are data measured using a master work MW having a known diameter. Further, the eccentric distance from the rotation axis O to the center C of the master work MW when these measurements are performed is the same distance from each other, and the eccentric direction is a direction in which the phases around the rotation axis O are different from each other. ..

The second measurement correction data is obtained by performing phase correction processing on the second measurement data so that the phase difference between the first measurement data and the second measurement data disappears.

Therefore, when the detection angle error of the rotation angle detection device 36 does not exist, the first measurement data and the second measurement correction data (second measurement data after the phase correction processing) have shapes that match each other. In the difference data between the 1 measurement data and the 2nd measurement correction data, the error (shape error component) at each circumferential position (rotation angle) should be originally 0.

On the other hand, when there is a detection angle error of the rotation angle detection device 36, the difference data between the first measurement data and the second measurement correction data is the detection angle error of the rotation angle detection device 36 as shown in FIG. Due to this, the first measurement data and the second measurement correction data do not have the same shape, and as described above, the radial position R error depends on the circumferential position θ at each measurement point on the surface of the work W. Variation occurs in ΔR.

Therefore, the magnitude of the detection angle error of the rotation angle detection device 36 can be easily grasped according to the magnitude of the shape error component of the difference data between the first measurement data and the second measurement correction data. For example, whether or not the shape error component of the difference data between the first measurement data and the second measurement correction data is within a predetermined allowable range (−ε ≦ Δ ≦ ε; where ε> 0). It is also possible to make a judgment and correct the detection angle error when the shape error component is within the permissible range and correct the detection angle error when the shape error component is within the permissible range.

(Calculation method of detection angle error)
Next, a method of calculating the detection angle error of the rotation angle detection device 36 will be described. FIG. 10 is a diagram for explaining a method of calculating the detection angle error.

First, in the first measurement data, for example, a measurement point (first measurement point; FIG. 4) measured when the indicated value of the rotation angle (detection angle of the rotation angle detection device 36) is 0 degrees (θ = 0). The radial position at (corresponding to the point P1 on the surface of the master work MW) is R ₀ . Further, as shown in FIG. 10, when the detection angle error corresponding to the indicated value (0 degree) of the rotation angle is A ₀ , the original radial position is R ₀ / cos A ₀ .

At this time, the shape error component ΔR _{0 at} the first measurement point is obtained from the following equation (1).

Next, in the second measurement correction data (second measurement data after the phase correction processing), the measurement point (second measurement point; corresponding to the point P2 on the surface of the master work MW in FIG. 6) whose circumferential position is 0 degree. ) _{Is R'φ} . The second measurement point corresponds to the measurement point when the circumferential position is φ degree in the second measurement data before the phase correction processing is performed. Further, the second measurement point in the second measurement correction data is measured when the indicated value of the rotation angle is φ degree (θ = φ), and the detection angle error at that time is A _φ . In this case, the shape error components [Delta] R _'phi at the second measurement point is determined from the following equation (2).

Difference between the shape error components [Delta] R _'phi shape error component [Delta] R ₀ in the first measurement point in the second measurement point is expressed by the following equation (3).

Here, when φ = 180 degrees, the following equations (4) and (5) hold.

Here, the left side "ΔR ₀ -ΔR ' ₁₈₀ " in the equation (4) is a position where the circumferential position of the surface of the master work MW is 0 degree (position corresponding to the point P1 in FIG. 4 and the point P2 in FIG. 5, respectively). It is the difference of the shape error component of the measurement result in.

_{Further, "ΔR 180} -ΔR ' ₀ " in the equation (5) is a position where the circumferential position of the surface of the master work MW is 180 degrees (a position in which the phase is 180 degrees different from the point P1 in FIG. 4 and the point P2 in FIG. 5). ) Is the difference in the shape error component of the measurement result.

Further, "R ₀ " and "R ₁₈₀ " indicate radial positions corresponding to the circumferential positions of the first measurement data of 0 degrees and 180 degrees, respectively. Further, "R _'180' and 'R'_0" indicates the radial position of the circumferential position of the second measurement correction data corresponding respectively to 180 degrees and 0 degrees.

Since A ₀ and A ₁₈₀ are the detection angle errors to be obtained, solving equations (4) and (5) for A ₀ and A ₁₈₀ gives the following equations (6) and (7). ..

Equations (6) and (7) are cases where the phase is shifted by 180 degrees at the 0 degree position.

Here, assuming that the circumferential position of the detection angle error to be obtained is α and the phase shift amount is β, the detection angle error A _α can be obtained by the following equation (8).

Therefore, when the radial position (R value) and the circumferential position (θ value) of each measurement point on the surface of the work W are measured by the roundness measuring machine 10, the circumferential position (θ value) is expressed by the equation (θ value). It is possible to improve the measurement accuracy of the surface shape of the work W by performing correction by replacing the detection angle error A _{α obtained in 8) with a true value (original rotation angle).}

Further, instead of correcting the circumferential position (θ value), it is also possible to correct the radial position (R value). That is, when the corrected radial position is cR _{α , the corrected radial position cR α} can be obtained by the following equation (9).

The angle error calculation unit 118 shown in FIG. 3 calculates the detected angle error A _α as a correction value for each rotation angle based on the above equation (8) (an example of the angle error calculation process). Then, an angle error correction table showing the detection angle error A _{α (correction value) for each rotation angle is created.} An example of the angle error correction table is shown in FIG. The angle error correction table created by the angle error calculation unit 118 is stored in the storage unit 108.

(Angle correction method in roundness measuring machine)
Next, the angle correction method in the roundness measuring machine 10 of the present embodiment will be described. This angle correction method is an example of the angle correction method according to the present invention.

FIG. 12 is a flowchart showing an angle correction method using the roundness measuring machine 10 of the present embodiment.

(Step S10: First measurement data acquisition step)
First, prior to the measurement of the work W which is the object to be measured, the first measurement is performed using the master work MW.

In the first measurement, as shown in FIG. 4, the center C of the master work MW placed on the rotary table 14 is shifted by a preset eccentric distance E in the first direction perpendicular to the rotation axis O (first measurement). 1) It is assumed that it is placed at the measurement position). Then, the stylus 32 of the detector 30 is brought into contact with the surface of the master work MW, and the displacement of the stylus 32 is detected by the detector 30 while rotating the master work MW by the rotary table 14. As a result, the first measurement data acquisition unit 112 has the diameter of each measurement point on the surface of the master work MW based on the detection signals output from the detector 30, the detector position detection device 34, and the rotation angle detection device 36, respectively. The directional position (R value) and the circumferential position (θ value) are calculated, and the first measurement data in which they are associated is acquired.

(Step S12: Second measurement data acquisition step)
Next, the second measurement is performed using the master work MW.

In the second measurement, as shown in FIG. 6, the center C of the master work MW placed on the rotary table 14 is eccentric by the eccentric distance E in the second direction whose phase around the rotation axis O is different from that of the first direction. It is assumed that it is placed at the position (second measurement position). Then, the stylus 32 of the detector 30 is brought into contact with the surface of the master work MW, and the displacement of the stylus 32 is detected by the detector 30 while rotating the master work by the rotary table 14. As a result, the second measurement data acquisition unit 114 has the diameter of each measurement point on the surface of the master work MW based on the detection signals output from the detector 30, the detector position detection device 34, and the rotation angle detection device 36, respectively. The directional position (R value) and the circumferential position (θ value) are calculated, and the second measurement data in which they are associated is acquired.

When the first measurement and the second measurement are performed, it is preferable to use the master work moving mechanism 40 shown in FIG. 13A and 13B are views showing a configuration example of the master work moving mechanism 40, where FIG. 13A is a top view and FIG. 13B is a side view.

As shown in FIG. 13, the master work moving mechanism 40 is arranged between the rotary table 14 and the master work MW. The master work moving mechanism 40 includes a rotary moving unit 42 and a horizontal moving unit 44 in this order from the rotary table 14 side.

The rotary moving unit 42 is configured to be rotatable around the same axis as the rotary axis O of the rotary table 14, and can rotate relative to the rotary table 14. The horizontal moving unit 44 is configured to be movable in one direction (horizontal direction) perpendicular to the rotation axis O of the rotational moving unit 42, and can move relative to the rotational moving unit 42. When the rotary moving portion 42 is rotated, the horizontal moving portion 44 also rotates integrally.

The drive mechanism for driving the rotary movement unit 42 and the horizontal movement unit 44 includes a manual mechanism that is manually driven by the user, an electric mechanism that is electrically controlled and drives, and the like. Further, it is preferable that the rotary moving portion 42 and the horizontal moving portion 44 are provided with locking means (not shown) so as to be locked at a predetermined position.

When performing the first measurement and the second measurement using such a master work moving mechanism 40, first, as shown in FIGS. 13A and 13B, a master is placed on the upper surface of the rotary table 14. The work moving mechanism 40 is placed, and then the master work MW is placed on the upper surface of the horizontal moving portion 44 constituting the master work moving mechanism 40.

When performing the first measurement, as shown in FIG. 14A, the master work MW is moved to the first measurement position by moving the horizontal moving portion 44 of the master work moving mechanism 40. Further, when the second measurement is performed after the first measurement is performed, as shown in FIG. 14B, the master work MW is rotated by rotating the rotary moving portion 42 of the master work moving mechanism 40. To the second measurement position.

By using the master work moving mechanism 40 when the first measurement and the second measurement are performed in this way, the master work MW can be moved accurately, easily, and quickly to the first measurement position and the second measurement position. Is possible.

(Step S14: Angle error correction table creation process)
Next, the angle error correction table creation unit 104 calculates the detection angle error for each rotation angle based on the first measurement data acquired in the first measurement and the second measurement data acquired in the second measurement. Then, an angle error correction table showing the detection angle error for each rotation angle is created and stored in the storage unit 108. Since the method of calculating the detection angle error is as described above, the description thereof will be omitted here.

(Step S16: Workpiece measurement process)
Next, the work W is placed on the rotary table 14 instead of the master work MW, the eccentricity is adjusted so that the center of the work exactly coincides with the rotation axis O, and then the stylus 32 of the detector 30 is mounted on the work W. The displacement of the stylus 32 is detected by the detector 30 while rotating the work W by the rotary table 14 in contact with the surface of the As a result, the measurement data generation unit 102 determines the radial position of each measurement point on the surface of the work W based on the detection signals output from the detector 30, the detector position detection device 34, and the rotation angle detection device 36, respectively. The R value) and the circumferential position (θ value) are calculated, and the measurement data associated with these is acquired.

(Step S18: Judgment step)
Next, the measurement data correction unit 106 reads the angle error correction table stored in the storage unit 108, and by referring to the angle error correction table, all of the detection angle errors corresponding to each rotation angle are preset. Determine if it is within the permissible range. Then, if all the detection angle errors are not within the permissible range, the process proceeds to the next step S20. On the other hand, if all the detection angle errors are within the permissible range, step S20 is skipped and the process proceeds to step S22.

(Step S20: Angle error correction step)
Next, the measurement data correction unit 106 corrects the measurement data generated by the measurement data generation unit 102 by referring to the angle error correction table read in step S18. For example, assuming that the radial position of the measurement data at a certain measurement point is R _i , the circumferential position (rotation angle) is θ _i, and θ _i includes the detection angle error A _i , the circumferential position. theta _i detected angular error a _i from 'a, the circumferential position theta' after the correction subtraction (or addition) value circumferential position of the corrected theta radial position corresponding to leave R _i. The measurement data correction process is performed on all measurement points on the surface of the work W. If the detection angle error corresponding to the rotation angle to be corrected does not exist in the angle error correction table, it is corrected based on the detection angle error calculated by the interpolation process from the rotation angles existing in the vicinity thereof. You may.

(Step S22: Measurement result output process)
Next, the measurement result of the work W is output to the output unit 110. When the measurement data is corrected by the measurement data correction unit 106, the measurement data after the correction processing is output, and when the correction processing is not performed, the measurement data generation unit 102 generates the measurement data. The measurement data is output as it is. This is the end of this flowchart.

(Effect of this embodiment)
According to the present embodiment, the first measurement data when the center C of the master work MW is eccentric in the first direction perpendicular to the rotation axis O by the eccentric distance E, and the center of the master work MW are the first. Correct the detection angle error of the rotation angle detection device 36 based on the second measurement data when the measurement is performed with the eccentric distance E eccentric in the second direction whose phase around the rotation axis O is different from that of the one direction. Can be done. As a result, the accuracy of indicating the rotation angle is improved, so that the surface shape of the work W can be measured with high accuracy without being affected by the detection angle error.

In particular, in the present embodiment, since the detection angle error can be corrected for each rotation angle, it is possible to measure the surface shape of the work W with high accuracy even if the detection angle error varies for each rotation angle. It becomes.

In the present embodiment, the circumferential position (θ value) of the measurement data when the work W is measured is corrected, but the radial position (R value) may be corrected. In this case, the corrected radial position can be calculated using the above-mentioned equation (9).

Further, in the present embodiment, in the first measurement data acquisition step (step S10) and the second measurement data acquisition step (step S12), the data processing apparatus 100 sequentially acquires the first measurement data and the second measurement data. Although shown as an example, the acquisition order of these measurement data may be reversed. Further, as long as the data processing device 100 can acquire at least the first measurement data and the second measurement data, the measurements for obtaining these measurement data may be performed separately in advance.

In the present embodiment, the case where the present invention is applied to a table rotation type roundness measuring machine has been described, but the present invention is not limited to this, and the detector rotates around the work. The present invention can be applied to a measuring machine, and the same effect can be obtained.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above examples, and it goes without saying that various improvements and modifications may be made without departing from the gist of the present invention. Is.

10 ... Roundness measuring machine, 12 ... Base, 14 ... Rotating table, 16 ... X direction fine movement knob, 18 ... Y direction fine movement knob, 20 ... Motor, 22 ... Column, 24 ... Carriage, 26 ... Arm, 28 ... Detection Instrument holder, 30 ... detector, 32 ... stylus, 34 ... detector position detector, 36 ... rotation angle detector, 40 ... masterwork moving mechanism, 42 ... rotating moving part, 44 ... horizontal moving part, 100 ... data Processing device, 102 ... Measurement data generation unit, 104 ... Angle error correction table creation unit, 106 ... Measurement data correction unit, 108 ... Storage unit, 110 ... Output unit, 112 ... First measurement data acquisition unit, 114 ... Second measurement Data acquisition unit, 116 ... Phase correction unit, 118 ... Angle error calculation unit, W ... Work, MW ... Master work

Claims (8)

A table on which the work is placed, a detector that detects the surface position of the work, a rotation mechanism that rotates the work relative to the detector about the rotation axis, and a rotation angle of the rotation mechanism are detected. An angle correction method for correcting a detection angle error of the rotation angle detection device of a surface shape measuring device including a rotation angle detection device.
The master work is rotated relative to the detector by the rotation mechanism in a state where the center of the master work placed on the table is eccentric by an eccentric distance in the first direction perpendicular to the rotation axis. While the first measurement data acquisition step of acquiring the first measurement data in which the surface position of the master work detected by the detector is associated with the detection angle of the rotation angle detection device,
With the center of the master work placed on the table eccentric by the eccentric distance in the second direction whose phase around the rotation axis is different from that of the first direction, the master work is moved by the rotation mechanism. A second measurement data acquisition step of acquiring second measurement data in which the surface position of the master work detected by the detector is associated with the detection angle of the rotation angle detection device while rotating relative to the detector. ,
An angle error correction step of correcting the detection angle error of the rotation angle detection device based on the first measurement data and the second measurement data, and
A method for correcting an angle of a surface shape measuring device. The angle error correction step is
A phase correction step of performing phase correction so that the measurement data of either one of the first measurement data and the second measurement data has no phase difference with respect to the other measurement data.
An angle error calculation step of calculating the detection angle error of the rotation angle detection device by comparing the one measurement data after the phase correction with the other measurement data.
The angle correction method for the surface shape measuring apparatus according to claim 1. In the angle error calculation step, the detection angle error of the rotation angle detection device is calculated for each rotation angle.
The angle correction method for the surface shape measuring device according to claim 2. The angle error correction step corrects the detection angle of the rotation angle detection device based on the detection angle error of the rotation angle detection device.
The angle correction method for a surface shape measuring device according to any one of claims 1 to 3. The angle error correction step corrects the surface position of the work detected by the detector based on the detection angle error of the rotation angle detection device.
The angle correction method for a surface shape measuring device according to any one of claims 1 to 3. The angle error correction step determines whether or not the detection angle error of the rotation angle detection device is within the permissible range, and if the detection angle error is within the permissible range, no correction is performed and the detection angle error is not performed. If is out of the permissible range, make a correction,
The angle correction method for a surface shape measuring device according to any one of claims 1 to 5. A table on which the work is placed, a detector that detects the surface position of the work, a rotation mechanism that rotates the work relative to the detector about the rotation axis, and a rotation angle of the rotation mechanism are detected. An angle correction device for correcting a detection angle error of the rotation angle detection device of a surface shape measuring device provided with a rotation angle detection device.
The master work is rotated relative to the detector by the rotation mechanism in a state where the center of the master work placed on the table is eccentric by an eccentric distance in the first direction perpendicular to the rotation axis. However, the first measurement data acquisition unit that acquires the first measurement data in which the surface position of the master work detected by the detector is associated with the detection angle of the rotation angle detection device.
With the center of the master work placed on the table eccentric by the eccentric distance in the second direction whose phase around the rotation axis is different from that of the first direction, the master work is moved by the rotation mechanism. A second measurement data acquisition unit that acquires second measurement data in which the surface position of the master work detected by the detector is associated with the detection angle of the rotation angle detection device while rotating relative to the detector. ,
An angle error correction unit that corrects the detection angle error of the rotation angle detection device based on the first measurement data and the second measurement data.
An angle correction device for a surface shape measuring device. A state in which the center of the master work is eccentric from the rotation axis in the first direction by the eccentric distance and a state in which the center of the master work is eccentric from the rotation axis in the second direction by the eccentric distance. Equipped with a switchable masterwork movement mechanism,
The angle correction device for the surface shape measuring device according to claim 7.

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