JP2018169266A - Angle correction method of surface shape measuring device, and angle correction device - Google Patents

Abstract

To provide an angle correction method of a surface shape measuring device and an angle correction device with which it is possible to improve the accuracy of measuring the surface shape of a workpiece without being affected by a detection angle error of a rotation angle detector.SOLUTION: A angle correction method comprises: a first measured data acquisition step S10 for acquiring first measured data when first measurement is performed while the center of a master workpiece is decentered by an eccentric distance in a first direction perpendicular to the axis of rotation; a second measured data acquisition step S12 for acquiring second measured data when second measurement is performed while the center of the master workpiece is decentered by an eccentric distance in a second direction differing in phase around the axis of rotation from the first direction; and an angle error correction step S20 for correcting a detection angle error of a rotation angle detector on the basis of the first measured data and the second measured data.SELECTED DRAWING: Figure 12

Description

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

  Conventionally, as a surface shape measuring apparatus for measuring the surface shape of a workpiece, a roundness measuring machine for measuring the roundness of the workpiece or the like is known (for example, see Patent Document 1).

  This type of surface shape measuring apparatus includes a table for placing a workpiece, a detector for detecting the surface position of the workpiece, a rotating mechanism for rotating the workpiece relative to the detector around a rotation axis, and a rotating mechanism. And a rotation angle detection device (for example, a rotary encoder) provided in.

  In the surface shape measuring device, the surface position of the workpiece accompanying the rotation of the workpiece (by detecting the surface position of the workpiece while rotating the workpiece placed on the table relative to the detector) The measurement data indicating the radial position and the circumferential position) is acquired, and parameters for evaluating the surface shape of the workpiece are calculated from the measurement data.

JP 2004-108787 A

  By the way, in the conventional surface shape measuring device, an error in the detection angle of the rotation angle detection device is caused by an eccentric error caused by eccentricity when the rotation angle detection device is attached to the rotation mechanism or a shape error caused by the shape of the rotation angle detection device. Will occur.

  For example, when the rotation angle detection device is mounted in an eccentric state with respect to the rotation shaft 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 there are variations in the shape of the rotation angle detection device, a random angle detection error occurs for each rotation angle as an error caused by the shape of the rotation angle detection device, as shown in FIG.

  Therefore, in the rotation angle detection device used in the conventional surface shape measurement device, the eccentricity error caused by the eccentricity when the rotation angle detection device is attached and the shape error caused by the shape of the rotation angle detection device are complicatedly entangled. Then, since an angle detection error as shown in FIG. 17 occurs, there is a problem that the measurement accuracy of the surface shape of the workpiece 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 workpiece without being affected by the detection angle error of the rotation angle detecting device. An object of the present invention is to provide an angle correction method and an angle correction device.

  In order to achieve the above object, the following invention is provided.

  An angle correction method for a surface shape measuring apparatus according to a first aspect of the present invention includes a table for placing a workpiece, a detector for detecting the surface position of the workpiece, and the workpiece relative to the detector around a rotation axis. An angle correction method for correcting a detection angle error of a rotation angle detection device of a surface shape measurement device comprising a rotation mechanism for rotating the rotation mechanism and a rotation angle detection device for detecting a rotation angle of the rotation mechanism, and is mounted on a table. The master work detected by the detector while rotating the master work relative to the detector by the rotation mechanism while the center of the placed master work is eccentric by the eccentric distance in the first direction perpendicular to the rotation axis The first measurement data acquisition step of acquiring the first measurement data in which the surface position of the rotation angle is associated with the detection angle of the rotation angle detector, and the first direction is the center of the master work placed on the table Rotation angle of the surface position of the master workpiece detected by the detector while rotating the master workpiece relative to the detector by the rotation mechanism with the eccentricity in the second direction with different phases around the rotation axis. Second measurement data acquisition step for acquiring second measurement data associated with the detection angle of the detection device, and angle error correction for correcting the detection angle error of the rotation angle detection device based on the first measurement data and the second measurement data A process.

  In the angle correction method of the surface shape measuring apparatus according to the second aspect of the present invention, in the first aspect, the angle error correction step is performed such that one of the first measurement data and the second measurement data is the other measurement data. The angle for calculating the detection angle error of the rotation angle detection device by comparing the phase correction process for correcting the phase so that the phase difference is eliminated, and one measurement data after the phase correction and the other measurement data. An error calculation step.

  In the angle correction method for the surface shape measuring apparatus 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 apparatus for each rotation angle.

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

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

  In the angle correction method for the surface shape measuring apparatus according to the sixth aspect of the present invention, in any one of the first to fifth aspects, the angle error correction step includes an allowable range of the detected angle error of the rotation angle detecting device. If the detected angle error is within the allowable range, the correction is not performed. If the detected angle error exceeds the allowable range, the correction is performed.

  An angle correction device for a surface shape measuring apparatus according to a seventh aspect of the present invention includes a table for placing a workpiece, a detector for detecting the surface position of the workpiece, and the workpiece relative to the detector around the rotation axis. An angle correction device for correcting a detection angle error of a rotation angle detection device of a surface shape measurement device comprising a rotation mechanism for rotating the rotation mechanism and a rotation angle detection device for detecting a rotation angle of the rotation mechanism, and mounted on a table The master work detected by the detector while rotating the master work relative to the detector by the rotation mechanism while the center of the placed master work is eccentric by the eccentric distance in the first direction perpendicular to the rotation axis The first measurement data acquisition unit for acquiring the first measurement data in which the surface position of the sensor is associated with the detection angle of the rotation angle detection device, and the center of the master work placed on the table as the first direction. Rotation angle detection of the surface position of the master workpiece detected by the detector while the master workpiece is rotated relative to the detector by the rotation mechanism in the second direction where the phase around the axis is decentered by the eccentric distance. A second measurement data acquisition unit that acquires second measurement data associated with the detection angle of the device, 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 And comprising.

  An angle correction device for a surface shape measuring apparatus according to an eighth aspect of the present invention, in the seventh aspect, wherein the center of the master work is eccentric from the rotation axis in the first direction by an eccentric distance, and the center of the master work is rotated. A master work moving mechanism capable of switching between a state eccentric from the shaft in the second direction by an eccentric distance is provided.

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

Schematic 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 showing how 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 showing how 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 of 1st measurement data and 2nd measurement correction data The figure which showed the 1st measurement data after polar coordinate conversion, and the 2nd measurement data The figure for explaining the calculation method of the detection angle error The figure which showed an example of the angle error correction table The flowchart figure which showed the angle correction method using the roundness measuring machine of this embodiment Diagram showing an example of the configuration of the master work movement mechanism Diagram showing an example of the master work movement mechanism Diagram showing an example of detection angle error (eccentricity error) due to eccentricity when the encoder scale is attached Diagram showing detection angle error (shape error) due to encoder scale shape The figure which showed an example of the detection angle error which occurs with the conventional surface shape measuring device

  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 exemplified as an example of a surface shape measuring apparatus to which the present invention is applied. However, the present invention is a variety of types of surface shape measuring for measuring the surface shape of a workpiece. Widely applicable to devices.

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

  As shown in FIG. 1, the roundness measuring machine 10 of this 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 direction and the Y direction by the X direction fine adjustment knob 16 and the Y direction fine adjustment knob 18, and in the X direction by the X direction inclination knob (not shown) and the Y direction inclination knob (not shown). The inclination is adjusted in the Y direction.

  The turntable 14 is rotatably supported by a motor 20 (an example of a rotation 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, and the rotation angle is read with high accuracy. The rotation angle detection device 36 is composed of, for example, a rotary encoder. For example, an ultra-high precision hydrostatic air bearing is used as the bearing, and the rotary table 14 is rotated with extremely high rotational accuracy (for example, 0.005 μm). The rotation angle detection device 36 detects the rotation angle of the work W placed on the rotary table 14 by detecting the rotation angle of the rotation shaft of the motor 20. A detection signal (rotation angle data) output from the rotation angle detection device 36 is input to the data processing device 100 described later. Note that the rotation angle detection device 36 is not limited to a rotary encoder, and may be, for example, a device that detects the rotation angle of the workpiece W based on information on a drive signal (number of pulses) of the motor 20 that drives the rotary table 14. Good.

  On the base 12, a column (support) 22 extending in the vertical direction (Z direction) is erected, and a carriage 24 is supported on the column 22 so as to be movable in the vertical direction (Z direction). An arm (radial movement axis) 26 is supported on the carriage 24 so as to be movable in a 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 probe 32 that contacts the surface of the workpiece W is detected. The detection signal (displacement data) output from the detector 30 is input to the data processing apparatus 100 described later.

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

  When measuring the roundness or the like of the workpiece W with the roundness measuring device 10 of the present embodiment, after the workpiece W is placed on the rotary table 14, the rotary axis (rotation center) O of the rotary table 14 is first set. The eccentricity correction with respect to the center of the workpiece W and the inclination correction of the workpiece 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 with the probe 32 of the detector 30 in contact with the surface (side surface) of the workpiece W, and data for one round of the surface of the workpiece W is collected. At this time, 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.

  The data processing apparatus 100 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 workpiece W are associated with each other based on the input detection signals. Based on the measured data, the roundness of the workpiece W is calculated. The result of the arithmetic processing by the data processing apparatus 100 is displayed on the output unit 110 such as a monitor or a printer.

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

  FIG. 2 is a functional block diagram showing the configuration of the data processing apparatus 100. The data processing apparatus 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 for performing various processes can be configured with a CPU, a memory, and other LSIs in terms of hardware, and loaded into the memory in terms of software. Realized by programs. That is, these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof, and is not limited to any one.

  The measurement data generation unit 102 determines the radial position (R value) of each measurement point on the surface of the workpiece W from the detection signals (displacement data and detection value position data) output from the detector 30 and the detector position detection device 34. While calculating, the circumferential position ((theta) value) of each measurement point is calculated from the detection signal (rotation angle data) output from the rotation angle detection apparatus 36, and the measurement data which linked | related these are produced | generated. The measurement data generation unit 102 outputs the measurement data generated in this way to the measurement data correction unit 106. Further, the measurement data is stored in the storage unit 108 as necessary.

  The angle error correction table creation unit 104 calculates a 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 refers to the angle error correction table, thereby measuring the measurement data generated by the measurement data generation unit 102 when measuring the workpiece W. The correction process is performed. The measurement data correction unit 106 outputs the measurement data subjected to the correction process to the output unit 110 such as a monitor or a printer. 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 creation 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 1st measurement data acquisition part 112 acquires the 1st measurement data when the 1st measurement using the master work MW (refer FIG. 4) with a known diameter is performed.

  FIG. 4 is a schematic diagram illustrating 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 turntable 14 is set in advance in a first direction perpendicular to the rotation axis O (in this example, the positive direction of the X direction). Further, it is assumed that it is arranged at a position (first measurement position) that is eccentric by an eccentric distance E. Then, with the master work MW placed at the first measurement position, the probe 32 of the detector 30 is brought into contact with the surface of the master work MW, and the probe 30 is rotated by the detector 30 while rotating the master work MW by the rotary table 14. 32 displacements are detected. As a result, the first measurement data acquisition unit 112 is based on the detection signals output from the detector 30, the detector position detection device 34, and the rotation angle detection device 36, and the diameter of each measurement point on the surface of the master work MW. A direction position (R value) and a circumferential position (θ value) are calculated, and first measurement data associated with these is obtained.

  FIG. 5 is a diagram illustrating 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 (master work center C) that is eccentric from the rotation axis O by the eccentric distance E in the first direction (plus direction in the X direction). Measurement data. 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 second measurement data when the second measurement using the master work MW (see FIG. 6) is performed. Note that the same master work MW is used for the first measurement and the second measurement.

  FIG. 6 is a schematic diagram illustrating 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 turntable 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 set as the state arrange | positioned in the position (2nd measurement position) eccentrically by the said eccentric distance E. That is, the second measurement position has a predetermined phase (rotation angle) in the predetermined rotation direction (in this example, the CCW direction (counterclockwise direction)) with the center C of the master work MW as the center from the first measurement position about the rotation axis O. ) The position is shifted in phase by φ. Then, with the master work MW placed at the second measurement position, the probe 32 of the detector 30 is brought into contact with the surface of the master work MW, and the probe 30 is rotated by the detector 30 while rotating the master work by the rotary table 14. The displacement of is detected. As a result, the second measurement data acquisition unit 114 has the diameter of each measurement point on the surface of the master workpiece 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. A direction position (R value) and a circumferential position (θ value) are calculated, and second measurement data in which these are associated is obtained.

  FIG. 7 is a diagram illustrating an example of 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 (master work center C) that is eccentric by the eccentric distance E in the second direction (the direction whose phase is shifted by φ from the first direction) from the rotation axis O. The second measurement data is a circular shape centered at. The second measurement data acquisition unit 114 outputs the second measurement data to the phase correction unit 116.

  The phase correction unit 116 performs phase correction processing that shifts the phase of the input second measurement data in the direction opposite to the rotation direction, that is, the CW direction (clockwise direction) by φ (an example of a phase correction step). ). As described above, the first measurement data and the second measurement data are obtained by performing the respective measurements (first measurement and second measurement) with the phase shifted by φ around the rotation axis O. Therefore, the phase correction is performed. The unit 116 performs phase correction processing of the second measurement data so as to eliminate the phase difference between the first measurement data and the second measurement data, thereby obtaining the first measurement data and the second measurement data after the phase correction processing. The phase is matched. The phase correction unit 116 outputs the second measurement correction data subjected to the phase correction processing to the angle error calculation unit 118. Hereinafter, the second measurement data after the phase correction process 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 is eliminated. Alternatively, phase correction processing 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 second measurement correction data. Then, an angle error correction table indicating the detected angle error for each rotation angle is created, and the angle error correction table is stored in the storage unit 108.

(Difference data between first measurement data and second measurement correction data)
FIG. 8 is a diagram illustrating an example of difference data between the first measurement data and the second measurement correction data. FIG. 8 shows difference data after polar coordinate conversion, where the horizontal axis indicates the circumferential position θ and the vertical axis indicates 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, symbol T1 indicates first measurement data, symbol T2 indicates second measurement data, and symbol T2p indicates second measurement correction data (second measurement data after phase correction processing).

  As shown in FIG. 8, the difference data between the first measurement data and the second measurement correction data varies in the error ΔR of the radial position R according to the circumferential position θ at each measurement point on the surface of the workpiece 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 whose diameter is known. Further, when these measurements are performed, the eccentric distance from the rotation axis O to the center C of the master work MW is the same distance, and the eccentric directions are directions in which 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 is eliminated.

  Therefore, when there is no detection angle error of the rotation angle detection device 36, the first measurement data and the second measurement correction data (second measurement data after the phase correction process) have a shape that matches each other. In the difference data between the 1 measurement data and the second measurement correction data, the error (shape error component) at each circumferential position (rotation angle) should be essentially 0.

  On the other hand, when the detection angle error of the rotation angle detection device 36 exists, 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 the above, the first measurement data and the second measurement correction data do not have the same shape, and as described above, the error in the radial position R according to the circumferential position θ at each measurement point on the surface of the workpiece 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 correct the detected angle error when the shape error component is within the allowable range, without correcting the detected angle error when the shape error component is within the allowable range.

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

First, in the first measurement data, for example, the measurement point (first measurement point; FIG. 4) measured when the instruction value of the rotation angle (detection angle of the rotation angle detection device 36) is 0 degree (θ = 0). The radial position at the point P1 on the surface of the master work MW is defined as _R0 . As shown in FIG. 10, when the detected angle error corresponding to the rotation angle instruction value (0 degree) 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 process), the measurement point (second measurement point; corresponding to the point P2 on the surface of the master work MW in FIG. 6) is 0 degrees in the circumferential direction. ) In the radial direction is _R′φ . The second measurement point corresponds to the measurement point when the circumferential position is φ degrees in the second measurement data before the phase correction process is performed. The second measurement point in the second measurement correction data is measured when the indicated value of the rotation angle is φ degrees (θ = φ), and the detected angle error at that time is A _φ . At this time, the shape error component ΔR ′ _{φ at} the second measurement point is obtained from the following equation (2).

The difference between the shape error component ΔR ₀ at the first measurement point and the shape error component ΔR ′ _{φ at} the second measurement point is expressed by the following equation (3).

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

Here, in the left side “ΔR ₀ -ΔR ′ ₁₈₀ ” in the formula (4), the circumferential position of the surface of the master work MW is a 0 degree position (a position corresponding to the point P1 in FIG. 4 and the point P2 in FIG. 5). This is the difference in the shape error component of the measurement result at.

In addition, “ΔR ₁₈₀ −ΔR ′ ₀ ” in Expression (5) indicates that the circumferential position of the surface of the master work MW is a 180 degree position (a position that is 180 degrees out of phase from the point P1 in FIG. 4 and the point P2 in FIG. 5). ) Is a difference between the shape error components of the measurement result.

“R ₀ ” and “R ₁₈₀ ” indicate radial positions corresponding to 0 ° and 180 ° in the circumferential position of the first measurement data, respectively. “R ′ ₁₈₀ ” and “R ′ ₀ ” indicate radial positions corresponding to the 180 ° and 0 ° circumferential positions of the second measurement correction data, respectively.

Since A ₀ and A ₁₈₀ are 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 of 180 degrees is shifted at the 0 degree position.

Here, if 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 measuring the radial position (R value) and the circumferential position (θ value) of each measurement point on the surface of the workpiece W in the roundness measuring machine 10, the circumferential position (θ value) is expressed by the formula ( by performing the true value (actual rotation angle) replaced with the correction in consideration of the detection angle error a _alpha obtained in 8), it is possible to improve the measurement accuracy of the surface shape of the workpiece W.

Further, instead of correcting the circumferential position (θ value), it is also possible to correct the radial position (R value). That is, when the radial position of the corrected was cR _alpha, it is possible to determine the radial position cR _alpha corrected by the following equation (9).

The angle error calculation unit 118 shown in FIG. 3 calculates the detected angle error _Aα as a correction value for each rotation angle based on the above-described equation (8) (an example of an angle error calculation step). Then, an angle error correction table indicating the detected 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 for roundness measuring machine)
Next, an angle correction method in the roundness measuring device 10 of the present embodiment will be described. This angle correction method is an example of an angle correction method according to the present invention.

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

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

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

(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 turntable 14 is eccentric by the eccentric distance E in the second direction in which the phase around the rotation axis O is different from the first direction. It is set as the state arrange | positioned in the made position (2nd measurement position). Then, the probe 32 of the detector 30 is brought into contact with the surface of the master work MW, and the detector 30 detects the displacement of the probe 32 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 workpiece 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. A direction position (R value) and a circumferential position (θ value) are calculated, and second measurement data in which these are associated is obtained.

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

  As shown in FIG. 13, the master work moving mechanism 40 is disposed 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 order from the rotary table 14 side.

  The rotation moving unit 42 is configured to be rotatable about the same axis as the rotation 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 radial direction (horizontal direction) perpendicular to the rotation axis O of the rotary moving unit 42, and can move relative to the rotary moving unit 42. In addition, when the rotational movement part 42 is rotated, the horizontal movement part 44 also rotates integrally.

  The drive mechanism that drives the rotational movement unit 42 and the horizontal movement unit 44 includes a manual mechanism that is manually driven by a user, an electric mechanism that is driven under electrical control, and the like. Moreover, it is preferable that the rotational movement part 42 and the horizontal movement part 44 are provided with the locking means (not shown) so that it may be locked in 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 formed on the upper surface of the turntable 14. The workpiece moving mechanism 40 is placed, and then the master workpiece MW is placed on the upper surface of the horizontal moving portion 44 constituting the master workpiece 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, the master work MW is rotated by rotating the rotational movement unit 42 of the master work movement mechanism 40 as shown in FIG. Is moved 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: Angular error correction table creation step)
Next, the angle error correction table creation unit 104 calculates a 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 indicating the detected angle error for each rotation angle is created and stored in the storage unit 108. Since the detection angle error calculation method is as described above, the description thereof is omitted here.

(Step S16: Workpiece measurement process)
Next, instead of the master work MW, the work W is placed on the turntable 14 and the eccentricity is adjusted so that the work center is exactly aligned with the rotation axis O, and then the probe 32 of the detector 30 is moved to the work W. The detector 30 detects the displacement of the probe 32 while rotating the work W by the rotary table 14. As a result, the measurement data generation unit 102 is configured to detect the radial position of each measurement point on the surface of the workpiece W (based on the detection signals output from the detector 30, the detector position detection device 34, and the rotation angle detection device 36). (R value) and circumferential position (θ value) are calculated, and measurement data relating these are obtained.

(Step S18: Determination 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 the detected angle errors corresponding to the respective rotation angles are set in advance. It is determined whether it is within the allowable range. If all the detected angle errors are not within the allowable range, the process proceeds to the next step S20. On the other hand, if all the detected angle errors are within the allowable range, step S20 is skipped and the process proceeds to step S22.

(Step S20: Angle error correction process)
Next, the measurement data correction unit 106 performs correction processing of 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 detected 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. Note that the measurement data correction process is performed on all measurement points on the surface of the workpiece W. Further, when there is no detected angle error corresponding to the rotation angle to be corrected in the angle error correction table, correction is made based on the detected angle error calculated by the interpolation process from the rotation angle existing in the vicinity thereof. May be.

(Step S22: Measurement result output process)
Next, the measurement result of the workpiece W is output to the output unit 110. The measurement data correction unit 106 outputs the measurement data after the correction processing when the correction processing is performed on the measurement data, and the measurement data generation unit 102 generates the correction data when the correction processing is not performed. The measurement data is output as it is. Thus, this flowchart is completed.

(Effect of this embodiment)
According to the present embodiment, the first measurement data measured when the center C of the master work MW is decentered by the eccentric distance E in the first direction perpendicular to the rotation axis O, and the center of the master work MW are the first. The detection angle error of the rotation angle detection device 36 is corrected based on the second measurement data measured with the eccentricity distance E being decentered in the second direction in which the phase around the rotation axis O is different from the first direction. Can do. Thereby, since the indication accuracy of the rotation angle is improved, the surface shape of the workpiece W can be measured with high accuracy without being affected by the detection angle error.

  In particular, in the present embodiment, the detection angle error can be corrected for each rotation angle, so even when there is a variation in the detection angle error for each rotation angle, the surface shape of the workpiece W can be measured with high accuracy. It becomes.

  In the present embodiment, the circumferential position (θ value) of the measurement data when the workpiece 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-described equation (9).

  In the present embodiment, the data processing device 100 sequentially acquires the first measurement data and the second measurement data in the first measurement data acquisition step (step S10) and the second measurement data acquisition step (step S12). Although shown as an example, the acquisition order of these measurement data may be reversed. Moreover, as long as the data processing apparatus 100 can acquire at least the first measurement data and the second measurement data, the measurement 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. However, the present invention is not limited to this, and a detector rotation type roundness in which a detector rotates around a workpiece is described. The present invention can also be applied to a measuring machine, and similar effects can be obtained.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to the above example, Of course, in the range which does not deviate from the summary of this invention, various improvement and deformation | transformation may be performed. It is.

  DESCRIPTION OF SYMBOLS 10 ... Roundness measuring machine, 12 ... Base, 14 ... Rotary table, 16 ... X direction fine movement knob, 18 ... Y direction fine movement knob, 20 ... Motor, 22 ... Column, 24 ... Carriage, 26 ... Arm, 28 ... Detection Holder ... 30 ... Detector, 32 ... Measurement element, 34 ... Detector position detection device, 36 ... Rotation angle detection device, 40 ... Master work movement mechanism, 42 ... Rotation movement unit, 44 ... Horizontal movement unit, 100 ... Data Processing unit 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 for placing a workpiece, a detector for detecting the surface position of the workpiece, a rotation mechanism for rotating the workpiece relative to the detector around a rotation axis, and a rotation angle of the rotation mechanism. An angle correction method for correcting a detection angle error of the rotation angle detection device of the surface shape measurement device including the rotation angle detection device,
With the center of the master work placed on the table being eccentric by an eccentric distance in a first direction perpendicular to the rotation axis, the master work is rotated relative to the detector by the rotation mechanism. A first measurement data acquisition step of acquiring first measurement data in which the surface position of the master workpiece detected by the detector is associated with a detection angle of the rotation angle detection device;
In the state where the center of the master work placed on the table is decentered by the eccentric distance in a second direction different in phase around the rotation axis from 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 workpiece 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 a detection angle error of the rotation angle detection device based on the first measurement data and the second measurement data;
An angle correction method for a surface shape measuring apparatus. The angle error correction step includes
A phase correction step of performing phase correction so that any 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 a detection angle error of the rotation angle detection device by comparing the one measurement data after the phase correction and the other measurement data;
The method for correcting an angle of a surface shape measuring apparatus according to claim 1, comprising: The angle error calculation step calculates a detection angle error of the rotation angle detection device for each rotation angle.
An angle correction method for a surface shape measuring apparatus 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 of the surface shape measuring apparatus of any one of Claim 1 to 3. The angle error correction step corrects the surface position of the workpiece detected by the detector based on a detection angle error of the rotation angle detector.
The angle correction method of the surface shape measuring apparatus of any one of Claim 1 to 3. The angle error correction step determines whether or not the detection angle error of the rotation angle detection device is within an allowable range. If the detection angle error is within the allowable range, no correction is performed, and the detection angle error is determined. If the value exceeds the allowable range, correct it.
The angle correction method of the surface shape measuring apparatus of any one of Claim 1 to 5. A table for placing a workpiece, a detector for detecting the surface position of the workpiece, a rotation mechanism for rotating the workpiece relative to the detector around a rotation axis, and a rotation angle of the rotation mechanism. An angle correction device for correcting a detection angle error of the rotation angle detection device of a surface shape measurement device comprising a rotation angle detection device,
With the center of the master work placed on the table being eccentric by an eccentric distance in a first direction perpendicular to the rotation axis, the master work is rotated relative to the detector by the rotation mechanism. A first measurement data acquisition unit that acquires first measurement data in which the surface position of the master workpiece detected by the detector is associated with the detection angle of the rotation angle detection device;
In the state where the center of the master work placed on the table is decentered by the eccentric distance in a second direction different in phase around the rotation axis from 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 workpiece 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 a 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 decentered by the eccentric distance in the first direction from the rotation axis, and a state in which the center of the master work is decentered by the eccentric distance in the second direction from the rotation axis. With a switchable master work movement mechanism,
The angle correction apparatus of the surface shape measuring apparatus according to claim 7.

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