JP2012145492A - Circularity measuring apparatus and misalignment quantity correction method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circularity measuring apparatus and a misalignment quantity correction method of the circularity measuring apparatus that accurately calculate the diameter value of a measurement object having a different diameter value from a reference measurement object by calculating and compensating the misalignment quantity.SOLUTION: A circularity measuring apparatus measures the circularity of a measurement object by aligning the center of the measurement object and the center of rotation and by rotating the measurement object relatively to a detection device. The circularity measuring apparatus comprises: means for measuring each of a plurality of reference measurement objects 26-1, 26-2 having a different diameter value and detecting the difference between the above measurements; means for calculating a misalignment quantity Y, which is a misalignment quantity between the generatrix of the reference measurement objects 26-1, 26-2 and a detection point where the detection device detects the measurement object, based on the difference between the measurements; and means for correcting the measurement value of an arbitrary measurement object based on the calculated misalignment quantity Y.

Description

  The present invention relates to a roundness measuring apparatus and a method for correcting the amount of misalignment thereof, and in particular, a deviation between a detection point at which a measuring element of a detector of a roundness measuring apparatus abuts a measuring object and a bus bar of the measuring object The present invention relates to a roundness measuring device having a function of calculating the amount of misalignment shown and correcting the amount of misalignment, and a method of correcting the amount of misalignment.

  Conventionally, a roundness measuring device (roundness measuring machine) that measures the roundness of a circular object such as a cylindrical object is known. This roundness measuring device, for example, places a measurement object (workpiece) having a circular cross section such as a cylindrical object on a rotatable mounting table, and contacts a tip (measurement element) on the surface of the work The outer shape of the circular cross section is measured by measuring and detecting the displacement of the tip terminal accompanying the rotation of the workpiece.

  For example, in Patent Document 1, in a roundness measuring machine, a horizontal arm that guides a contact of a first detector horizontally and diametrically with respect to a cylindrical workpiece, and a tip of the arm are provided. A first detector support frame that enables the contact of the first detector to contact two points in the diameter position, and a second detector of diameter reading that detects the horizontal movement amount of the horizontal arm. A diameter measuring device of a roundness measuring machine composed of: This device first sets the master piece on the turntable, places the contact of the first detector on the right side of the master piece, obtains the reading of the second detector, and then places the contact on the left side of the master piece. Then, the reading of the second detector is obtained, and the error value of this apparatus is calculated from the two readings of the second detector according to the known dimensions of the master. Then, a workpiece is set instead of the master, and the diameter dimension is measured in the same manner to perform error correction.

  Patent Document 2 discloses a reference jig for a roundness measuring machine that performs origin calibration of a roundness measuring machine and calibrates a detector that measures the surface shape of a measurement object. A pedestal that is detachably mounted on the upper surface of the XY table on the rotary table, and a calibration master that enables calibration of the sensitivity of the probe (detector) on the upper stage of the pedestal. Provided with an origin ball (reference sphere) arranged so that measurement is possible in the X-axis direction and the right side of the lowermost surface, the right side, and the Z-axis direction of the left side above the calibration master, There is described a correction value obtained by obtaining a positional deviation of a stylus (sensor) provided in the probe in each posture of the probe. This is to obtain the origin information of the roundness measuring machine by placing the reference jig for the roundness measuring machine on the measured object rotating mechanism and bringing the sensor of the roundness measuring machine's detector into contact with the reference sphere. At the same time, the sensitivity of the detector is calibrated by involving the sensor of the detector in the calibration master.

JP-A-1-259211 Japanese Patent No. 4163545

  However, when the measurement object is placed on the table of the roundness measuring device and the detection element of the detector is brought into contact with the measurement object, detection is performed so that the bus bar of the measurement object and the measurement element are in contact with the measurement object. It is very difficult to match the points, and there is a problem in that an accurate diameter value cannot be measured for a measurement object having a diameter value different from the diameter value of the measurement object that has been the standard.

  The present invention has been made in view of such problems, and calculates and corrects the amount of misalignment, which is the amount of deviation between the bus of the measurement object and the detection point, and the diameter value of the measurement object serving as a reference. An object of the present invention is to provide a roundness measuring apparatus capable of calculating an accurate diameter value even for a measurement object having different diameter values, and a method for correcting the amount of misalignment thereof.

  In order to achieve the object, the invention according to claim 1 makes the center of the measurement object coincide with the center of rotation, rotates the measurement object relative to the detector, and sets the roundness of the measurement object. In the roundness measuring apparatus for measuring the measurement, a plurality of reference measurement objects having different diameter values are respectively measured, a measurement difference is detected, and a bus of the reference measurement object and the detector based on the measurement difference Means for calculating the amount of misalignment, which is the amount of deviation from the detection point with respect to the reference measured object, and means for correcting the measured value of an arbitrary measured object based on the calculated amount of misalignment. A roundness measuring device characterized by the above is provided.

  According to the first aspect of the present invention, the measurement object having a diameter value different from the diameter value of the reference measurement object is obtained by calculating and correcting the misalignment amount that is the deviation between the bus bar of the measurement object and the detection point. However, it is possible to calculate the exact diameter value.

  According to a second aspect of the present invention, the center of the measurement object is a center of a least square circle of a figure formed by a point on the outer periphery of the measurement object that is in contact with the detector during measurement. And

  As a result, even when the object to be measured is not a perfect circle, accurate measurement can be performed as close to a perfect circle as possible.

  Similarly, in order to achieve the object, the invention according to claim 3 is configured such that the center of the measurement object and the center of rotation coincide with each other and the measurement object is rotated relative to the detector. A measurement difference detection step of measuring a plurality of reference measurement objects having different diameter values and detecting the measurement difference, and based on the detected measurement difference, the reference measurement object bus and the detector The misalignment amount calculation step for calculating the amount of misalignment, which is the amount of deviation from the detection point with respect to the object, and the center of the measurement object and the center of rotation are made to coincide with each other so that the measurement object is rotated relative to the detector And a method of correcting a measured value obtained by measuring an arbitrary measurement object based on the calculated amount of misalignment, and a method of correcting the amount of misalignment in a roundness measuring device, I will provide a.

  According to the third aspect of the present invention, the measurement object having a diameter value different from the diameter value of the reference measurement object is obtained by calculating and correcting the misalignment amount that is the deviation between the bus bar of the measurement object and the detection point. However, it is possible to calculate the exact diameter value.

  According to a fourth aspect of the present invention, the center of the measurement object is a center of a least square circle of a figure formed by a point on the outer periphery of the measurement object that contacts the detector during measurement. And

  As a result, even when the object to be measured is not a perfect circle, accurate measurement can be performed as close to a perfect circle as possible.

  As described above, according to the present invention, by calculating and correcting the amount of misalignment that is the deviation between the bus of the measurement object and the detection point, the measurement object having a diameter value different from the diameter value of the reference measurement object can be obtained. Even if it exists, it becomes possible to calculate the exact diameter value.

It is a perspective view which shows the external appearance of the roundness measuring apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the roundness measuring apparatus of FIG. It is a perspective view which shows the external appearance of the measuring machine main body of a detector rotation type roundness measuring apparatus. It is a top view which shows the ideal case without misalignment when measuring a measurement object with a roundness measuring device. It is a top view which shows the case where there exists a center shift | offset | difference when measuring a measurement object with a roundness measuring apparatus. It is a top view which shows a mode that two reference | standard measurement objects which have a known different diameter are measured, and the amount of misalignment is calculated | required. It is a top view which shows the method of correct | amending using the amount of misalignment Y which calculated the value of the measured radius. It is a top view which shows the case where the value which measured the outer diameter or inner diameter of the measurement object is correct | amended with the amount of misalignment. It is a top view which shows a mode that three reference | standard measurement objects which have a known different diameter are measured, and the amount of eccentricity and the diameter of a tip sphere are calculated | required.

  Hereinafter, with reference to the attached drawings, a roundness measuring device and a method of correcting misalignment thereof according to the present invention will be described in detail.

  FIG. 1 is a perspective view showing an appearance of a roundness measuring apparatus according to an embodiment of the present invention.

  This roundness measuring apparatus is composed of a measuring machine main body and an arithmetic processing unit. FIG. 1 shows a measuring machine main body 11 of a roundness measuring apparatus 10.

  The measuring machine main body 11 is provided with a mounting table (XY / tilting table) 12 on which a measuring object (not shown here) is mounted on a base (base) 14. The mounting table (XY / tilting table) 12 includes an X direction fine movement knob 22 and a Y direction fine movement knob 24. The X direction fine movement knob 22 and the Y direction fine movement knob 24 are respectively connected to the mounting table moving shaft, and the fine movement knobs 22 and 24 can finely feed the mounting table 12 in the X direction and the Y direction. The horizontal position of the stage 12 can be finely adjusted.

  Further, the stage 12 is provided with an X-direction tilt knob 25 and a Y-direction tilt knob 23 so that the tilt can be adjusted in the X direction and the Y direction.

  A rotation mechanism 15 is provided at the lower part of the stage 12. The rotating mechanism 15 rotates the workpiece placed on the stage 12 by rotating the stage 12.

  Further, a column (support) 27 extending vertically upward is provided on the base 14, and a slider 28 is mounted on the column 27 so as to be movable up and down. A horizontal arm (radial movement axis) 29 is mounted on the slider 28 so as to be driven in the horizontal direction.

  A detector 30 is provided at the tip of the horizontal arm 29, and the detector 30 includes a probe 31. The roundness measuring apparatus 10 measures the measured object by bringing the measuring element 31 into contact with the measured object placed on the mounting table 12, and calculates a detection signal obtained by the measurement via the detector 30. The data is sent to the apparatus and processed by an arithmetic processing unit. A center misalignment adjusting mechanism 32 is provided at the tip of the horizontal arm 29.

  FIG. 2 is a block diagram showing the configuration of the roundness measuring apparatus 10.

  As shown in FIG. 2, the roundness measuring device 10 includes a measuring machine main body 11 and an arithmetic processing device 13. The measuring machine main body 11 will be described again although there are some points that overlap the description of FIG.

  The measuring machine main body 11 is provided with a mounting table 12 that is rotated by a rotating mechanism 15 on a base 14. The mounting table 12 is provided with an X-direction fine adjustment knob 22, a Y-direction fine adjustment knob 24, an X-direction inclination knob 25, and a Y-direction inclination knob 23 for fine adjustment in the horizontal direction and inclination adjustment in the vertical direction. Yes.

  The stage 12 is rotated by a rotation mechanism 15 including a bearing 16, an encoder 18, a motor 20, and the like. The stage 12 is rotatably supported by a motor 20 via a bearing 16. An encoder 18 is attached to the rotation shaft of the motor 20, and the rotation angle is read with high accuracy. For example, an ultra-high precision static pressure air bearing is used as the bearing 16, and the mounting table 12 is rotated with very high rotational accuracy (for example, 0.005 μm).

  Further, a slider 28 is mounted on a column (post) 27 erected on the base 14 so as to be movable up and down, and a horizontal arm (radial movement axis) 29 is mounted on the slider 28 so as to be driven in the horizontal direction. . A detector 30 is provided at the tip of the horizontal arm 29, and a probe 31 is installed on the detector 30. In addition, an electric micrometer using a differential transformer is used for the detector 30 to detect the amount of displacement of the probe 31 that contacts the measurement object 26.

  At the time of measurement, the measurement object 26 is placed on the mounting table 12, and the measuring element 31 is brought into contact with the measurement object to perform measurement. A detection signal obtained by the measurement is sent to the arithmetic processing unit 13 via the detector 30.

  The arithmetic processing unit 13 includes an amplifier 33, an A / D converter 34, an arithmetic / processing unit 36, and a program 38 stored in a memory for controlling these, and further includes a display unit for displaying the processing result. Yes.

  A detection signal obtained by bringing the probe 31 into contact with the measurement object 26 is sent to the arithmetic processing unit 13 via the detector 30. In the arithmetic processing unit 13, the signal is first amplified by the amplifier 33, converted into a digital signal by the A / D converter 34, and input to the arithmetic / processing means 36.

  When the roundness of the measuring object 26 is measured by the roundness measuring apparatus 10, after the measuring object 26 is placed on the mounting table 12, first, the center of rotation of the mounting table 12 and the measuring object are measured. The eccentricity correction with respect to the center of the object 26 and the inclination correction of the measurement object 26 with respect to the rotation axis of the mounting table 12 are performed. As a result, it is assumed that the center of rotation of the stage 12 and the center of the measurement object 26 coincide with each other.

  Next, in a state where the probe 31 of the detector 30 is in contact with the side surface of the measurement object 26, the mounting table 12 is rotated once by the motor 20, and the data for one round of the side surface of the measurement object 26 is converted into an analog voltage value. Collected. The detection signal obtained as an analog voltage value is amplified by the amplifier 33 as described above, converted into a digital signal by the A / D converter 34, and input to the arithmetic / processing means 36. The calculation / processing unit 36 calculates the roundness of the measurement object 26 from the rotation angle data input from the encoder 18 and the displacement data detected by the detector 30, and displays the calculation result on the display unit 40.

  In the roundness measuring apparatus 10 described above, the stage 12 on which the measurement object 26 is placed rotates, and the measuring element 31 moves in the front-rear direction (movement direction of the horizontal arm 29) and in the vertical direction (movement of the slider 28). In this case, the measuring element 31 does not rotate and moves in the direction), and the roundness measuring device of the mounting table rotation type is used. However, the present invention is limited to such a mounting table rotation type roundness measuring device. Is not to be done. It can also be applied to a roundness measuring device with a rotating detector, where the stage does not rotate, the probe moves in the front-rear and up-down directions, and the probe rotates around the workpiece. is there.

  FIG. 3 is a perspective view showing an appearance of a measuring machine main body of the detector rotation type roundness measuring apparatus.

  As shown in FIG. 3, the measuring machine main body 111 of the roundness measuring apparatus 100 is provided with a mounting table 112 on which a measuring object is placed on a base 114. The stage 112 has an X direction fine movement knob 122 and a Y direction fine movement knob 124. Although omitted here, an X-direction tilt knob and a Y-direction tilt knob may be provided as in the previous example.

  On the base 114, a column (post) 127 extending substantially vertically upward is erected, and a slider 128 is mounted on the column 127 so as to be movable up and down. The slider 128 is moved up and down by a feeding device 150 provided in the column 127. A horizontal arm (radial movement axis) 129 is attached to the lower side of the slider 128, and a detector 130 and a measuring element 131 are installed on the horizontal arm 129.

  The roundness measuring apparatus 100 measures the measurement object by rotating the measurement element 131 around the measurement object while bringing the measurement element 131 into contact with the measurement object placed on the mounting table 112. A detection signal obtained by the measurement is sent to an arithmetic processing device (not shown) via the detector 130 and processed by the arithmetic processing device. A misalignment adjusting mechanism 132 is installed between the horizontal arm 129 and the detector 130.

  Hereinafter, calculation of the amount of misalignment by the roundness measuring apparatus 10 (or 100) of the present embodiment and a method of correcting the amount of misalignment using this will be described.

  At the time of roundness measurement, as shown in FIG. 4, the tip sphere 31a of the probe 31 is brought into contact with the measuring object 26 placed on the mounting table 12 (not shown here).

  Then, in the case of the mounting table rotation type roundness measuring apparatus 10, the measuring object 26 is rotated by rotating the mounting table 12 as indicated by an arrow A in FIG. 4. Further, in the case of the detector rotation type roundness measuring apparatus 100, as shown by an arrow B in FIG. 4, the probe 31 (tip sphere 31a) is rotated along the outer periphery of the measurement object 26. It is assumed that the center of the measurement object 26 and the center of rotation of the mounting table 12 coincide with each other. Here, the center of the measuring object 26 refers to a figure forming the outer periphery of the measuring object 26 (more precisely, a point (detection point) measured by bringing the tip sphere 31a into contact with the surface of the mounting table 12). Suppose that it is the center of the least square circle of the outer periphery of the parallel section.

  At this time, the tip sphere 31a of the probe 31 is in contact with the measurement object 26 in any case. For example, in the case of the mounting table rotation type roundness measuring apparatus 10, as shown by an arrow D in FIG. 4, while the tip sphere 31 a is always pressed against the outer surface of the measured object 26, the measured object 26 is moved to the arrow. Rotate in direction A. At this time, if the measured object 26 is not a perfect circle and the radius changes as the measured object 26 rotates, the tip sphere 31a moves toward or away from the center of rotation, and its position changes in the direction of arrow D.

  The change in the position of the tip sphere 31 a is detected via the detector 30 and processed by the arithmetic / processing device 13 to detect the roundness of the measurement object 26.

  As shown in FIG. 4, a detection point P at which measurement is performed by moving the tip sphere 31 a of the probe 31 in the detection direction indicated by the arrow D and making contact with the measurement object 26 is a bus M passing through the center of the measurement object 26. , The roundness of the measurement object 26 can be accurately measured.

  However, in actual measurement, the detection point P of the tip sphere 31 a of the probe 31 with respect to the measurement object 26 does not always coincide with the bus M of the measurement object 26.

  Depending on the apparatus, for example, as shown in FIG. 5, the detection point Q at which the tip sphere 31 a of the probe 31 contacts the measurement object 26 may not coincide with the bus M of the measurement object 26. In this case, the measurement error is the distance ε between the centers of the tip spheres 31a in the detection direction D of the tip sphere 31a at the detection point P that coincides with the bus M of the measurement object 26 and the detection point Q in the actual measurement. Occurs.

  Further, the distance Y between the centers of the tip spheres 31a in the detection point P and the detection point Q in the direction perpendicular to the detection direction D represents the deviation of the detection point Q from the bus M, and this value Y Is the amount of misalignment.

  Next, a method for obtaining the misalignment amount Y will be described.

  In the method described below, two reference measured objects (diameter values are known) having different diameter values are measured, and the misalignment amount Y is calculated from the measured values.

As shown in FIG. 6, two reference measurement objects 26-1 and 26-2 having different known diameter values are measured by the roundness measuring device 10. The diameter value of the reference measurement object 26-1 _{D 1,} the diameter values of the reference measurement object 26-2 and _{D 2.} The diameter of the tip sphere 31a is d.

Here, tip sphere 31a of the probe 31, no eccentricity, the detection point on the assumption that it has proper contact with the reference measurement object 26-1 and P _1. That detection point P ₁ is to be consistent with the generating line M of the reference measurement object 26-1. Further, the detection value at this time is R _1. R ₁ is the sum of the radius of the reference workpiece 26-1 _(D 1/2) to the radius of the stylus tip _{31a (d / 2), R} 1 = a (D 1/2) + ( d / 2).

Similarly, end ball 31a of the probe 31, no eccentricity, the detection point on the assumption that it has proper contact with the reference measurement object 26-2 and P _2. That detection point _{P 2} coincides with the generating line M of the reference workpiece 26-2 (the same as the generating line of the reference measurement object 26-1). When the detection value at this time is _{R 2, R 2} is the sum of the radius (d / 2) of the radius of the reference workpiece 26-2 _(D 2/2) and the tip sphere _{31a, R 2 = (D 2} / 2) + (d / 2).

However, there are misalignments in actual measurements. If misalignment is present, the detection point tip sphere 31a of the probe 31 is in contact with the reference measurement object 26-1 and Q _1, the detection value at that time as R _{1 '.} Similarly, in actual measurement, if the misalignment is present, the detection point tip sphere 31a of the probe 31 is in contact with the reference measurement object 26-2 and Q _2, the detection value at that time and R _{2 '.} Also, Y is the distance (center misalignment) between the center of the tip sphere 31a and the bus M of the measured object 26-1 (26-2) in actual measurement.

At this time, as can be seen from FIG. 6, the detection values R ₁ ′ and R ₂ ′ are obtained by the following equations (1) and (2), respectively.

_{R 1 '= √ [{(} D 1/2) + (d / 2)} 2 -Y 2] ... (1)
_{R 2 '= √ [{(} D 2/2) + (d / 2)} 2 -Y 2] ... (2)
Here, √ [*] is a symbol representing the square root of *.

Than this is obtained by measuring the two reference measurement object 26-1,26-1 measurements _{(R 1} '-R _2') is expressed by the following equation (3).

_{(R 1 '-R 2')} = √ [{(D 1/2) + (d / 2)} 2 -Y 2]
_{- √ [{(D 2/} 2) + (d / 2)} 2 -Y 2] ... (3)
Therefore, the equation (3) is solved from the measured values (R ₁ ′ −R ₂ ′) obtained by measuring the two reference measured objects 26-1 and 26-2 having the known diameter values D ₁ and D _2. Thus, the misalignment amount Y can be calculated.

  Next, a method for correcting the measured radius value and the like using the calculated misalignment amount Y will be described.

  First, a case where the radius is measured and corrected will be described with reference to FIG.

7, a known master the diameter of the reference workpiece 26-0 and D _0, consider the case of measuring by using the stylus tip 31a of which diameter d.

  In FIG. 7, the measurement radius is R ′, and the amount of misalignment already obtained as described above is Y.

  If the calibration radius R obtained by correcting the measurement radius R ′ obtained by this measurement using the misalignment amount Y is R, the calibration radius R can be obtained by the following equation (4).

R = √ [{(D ₀ + d) / 2} ² −Y ² ] (4)
Next, with reference to FIG. 8, the case where the outer diameter or inner diameter of the measurement object is measured will be described.

First, considering the case of measuring the outer diameter of the measurement object 26-3, in FIG. 8, the distance from the center of the measurement object 26-3 to the center of the tip sphere 31a is √ [R ² + Y ² ]. Accordingly, the outer diameter can be obtained by substituting the diameter d of the tip sphere 31a from twice this, so that the outer diameter D can be obtained by the following equation (5).

D = 2 × √ [R ² + Y ² ] −d (5)
Next, when measuring the inner diameter of the measurement object 26-4, the tip sphere 31a is inscribed in the measurement object 26-4, so that the measurement object 26-4 represented by √ [R ² + Y ² ] is measured. Since the diameter d of the tip sphere 31a has only to be added to the distance from the center to the center of the tip sphere 31a, the following formula (6) is obtained.

D = 2 × √ [R ² + Y ² ] + d (6)
As described above, according to the present embodiment, even if the detection point where the tip sphere of the probe contacts the measurement object does not coincide with the bus line passing through the center of the measurement object, By calculating this misalignment amount, the measured value of the radius can be corrected using the misalignment amount.

  In this way, by calculating and correcting the deviation (center misalignment) between the bus of the measurement object and the detection point, even if the measurement object has a diameter value different from the diameter value of the reference measurement object, its exact diameter The value can be calculated.

  In addition to correcting the measured value using the calculated amount of misalignment, the position of the probe 30 and the tip sphere 31a (reference position) is determined by the misalignment adjusting mechanism 32 based on the calculated amount of misalignment. You may make it adjust.

  In the example described above, the amount of misalignment is calculated by measuring two reference measurement objects having different diameter values, but the number of reference measurement objects to be measured is not limited to two. For example, three reference measurement objects having different diameter values may be measured. In this case, not only the amount of misalignment but also the diameter of the tip sphere can be calculated. Therefore, even when the diameter of the tip sphere changes due to wear, an accurate diameter value can be obtained.

  Hereinafter, this will be described with reference to FIG.

As shown in FIG. 9, a case where three circles C ₁ , C ₂ and C ₃ having the same center and known diameters are measured is considered. The diameters of the _three circles C ₁ , C ₂ , and C ₃ are δ ₁ , δ ₂ , and δ ₃ , respectively.

First, when there is no misalignment, the measured values when these three circles C ₁ , C ₂ , and C ₃ are measured as shown in the figure are ρ ₁ , ρ ₂ , and ρ ₃ , respectively.

Further, when there is a misalignment (center misalignment amount Y), the measured values when these three circles C ₁ , C ₂ , and C ₃ are measured are denoted by ρ ₁ ′, ρ ₂ ′, and ρ ₃ ′, respectively. . The diameter value of the tip sphere 31a is d.

Then, when there is no misalignment, the measured values ρ ₁ , ρ ₂ , and ρ ₃ are expressed by the following equations (7) to (9).

_{ρ 1 = δ 1/2 +} d / 2 ... (7)
_{ρ 2 = δ 2/2 +} d / 2 ... (8)
_{ρ 3 = δ 3/2 +} d / 2 ... (9)
Further, the measured values ρ ₁ ′, ρ ₂ ′, and ρ ₃ ′ when there is a misalignment are expressed by the following equations (10) to (12).

_{ρ 1 '= √ [(δ} 1/2 + d / 2) 2 -Y 2] ... (10)
_{ρ 2 '= √ [(δ} 2/2 + d / 2) 2 -Y 2] ... (11)
_{ρ 3 '= √ [(δ} 3/2 + d / 2) 2 -Y 2] ... (12)
Therefore, the circle C ₁ and the circle C ₂ are measured to obtain the measurement value ρ ₁ ′ −ρ ₂ ′, and the circle C ₁ and the circle C ₃ are measured to obtain the measurement value ρ ₁ ′ −ρ ₃ ′.

  On the other hand, the following formulas (13) and (14) are obtained from the above formulas (10) to (12).

_{ρ 1 '-ρ 2' = √} [(δ 1/2 + d / 2) 2 -Y 2]
_{- √ [(δ 2/2} + d / 2) 2 -Y 2] ... (13)
_{ρ 1 '-ρ 3' = √} [(δ 1/2 + d / 2) 2 -Y 2]
_{- √ [(δ 3/2} + d / 2) 2 -Y 2] ... (14)
Therefore, the amount of misalignment Y and the diameter d of the tip sphere 31a can be calculated from the measured values ρ ₁ ′ −ρ ₂ ′ and ρ ₁ ′ −ρ ₃ ′ and equations (13) and (14).

  In this way, by measuring three reference measurement objects whose diameter values are known, it is possible to determine not only the amount of misalignment Y but also the diameter d of the tip sphere 31a.

  In the above description, the example using the platform rotation type roundness measuring apparatus 10 has been described. However, the present invention can also be suitably applied to the detector rotation type roundness measuring apparatus 100. .

  As described above, the roundness measuring apparatus and the misalignment correction method of the present invention have been described in detail. However, the present invention is not limited to the above examples, and various improvements can be made without departing from the gist of the present invention. It goes without saying that or may be modified.

  DESCRIPTION OF SYMBOLS 10 ... (mounting table rotation type) Roundness measuring device, 11 ... Measuring machine main body, 12 ... Mounting table (XY / tilting table), 13 ... Arithmetic processing device, 14 ... Base (base), 15 ... Rotation Mechanism: 16 ... Bearing, 18 ... Encoder, 20 ... Motor, 22 ... X direction fine adjustment knob, 23 ... Y direction fine adjustment knob, 24 ... Y direction fine adjustment knob, 25 ... X direction fine adjustment knob, 26 ... Measurement object, 27 ... Column (Posts), 28 ... slider, 29 ... horizontal arm (radial movement axis), 30 ... detector, 31 ... measuring element, 31a ... tip ball, 32 ... decentering adjustment mechanism, 33 ... amplifier, 34 ... A / D Converter, 36 ... arithmetic / processing means, 38 ... program, 40 ... display means, 100 ... (detector rotation type) roundness measuring device

Claims (4)

In a roundness measuring apparatus for measuring the roundness of a measurement object by rotating the measurement object relative to the detector by matching the center of the measurement object with the center of rotation,
Means for measuring a plurality of reference measurement objects having different diameter values and detecting the measurement difference;
Means for calculating a misalignment amount, which is a deviation amount between a bus of the reference measurement object and a detection point of the detector with respect to the reference measurement object, based on the measurement difference;
Means for correcting a measurement value of an arbitrary measurement object based on the calculated amount of misalignment;
A roundness measuring apparatus comprising:   2. The perfect circle according to claim 1, wherein the center of the measurement object is a center of a least-square circle of a figure formed by a point on the outer periphery of the measurement object that contacts the detector during measurement. Degree measuring device. The measurement object is rotated relative to the detector by aligning the center of the measurement object and the center of rotation, and a plurality of reference measurement objects having different diameter values are measured, and the measurement difference is detected. A measurement difference detection process;
Based on the detected measurement difference, a misalignment amount calculating step of calculating a misalignment amount that is a shift amount between a bus of the reference measurement object and a detection point of the detector with respect to the reference measurement object;
The measured value obtained by measuring an arbitrary measurement object by rotating the measurement object relative to the detector with the center of the measurement object and the center of rotation being coincident with each other is calculated as the calculated amount of misalignment. Correcting based on
A method of correcting the amount of misalignment in a roundness measuring apparatus comprising:   4. The perfect circle according to claim 3, wherein the center of the measurement object is a center of a least-square circle of a figure formed by a point on the outer periphery of the measurement object that contacts the detector during measurement. A method for correcting the amount of misalignment in a degree measuring device.

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