JPH1163971A - Circularity measuring machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring without being influenced by movement precision of a Z guide when a circularity measuring machine of a table rotary type measures a plurality of sections of a work and acquires a coaxial degree and a cylindrical degree. SOLUTION: A detector holder 16 is provided in a Z table in parallel to a detector holder 15, and a detector 17 and a detector 18 are provided in the respective detector holders in a state that a mutual detection direction is counter to a rotation center Tc of a rotary table 12. An average value of a first measurement value detected by the detector 17 and a measurement value detected by the detector 18 by rotating a work at 180 deg. by the rotation table 12 is set as a measuring value (radius) of the work at the point. Thereby, even if there is an error of movement precision of a Z guide, an error Ea of the movement precision is cancelled by an average of the two measuring values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roundness measuring device for measuring the roundness and cylindrical shape of an object to be measured (referred to as "work" in this specification). Related to a roundness measuring machine.

[0002]

2. Description of the Related Art As shown in FIG. 3, a roundness measuring machine of a table rotation type has a base 11 provided with a rotation table 12 which rotates around a vertical axis, and a Z guide 13 provided upright on the base 11. The Z table 24 is supported by the Z guide 13 so as to be movable in the Z direction. A detector holder 15 is supported on the Z table 24 so as to be movable in a horizontal uniaxial direction (X direction), and a detector 17 is provided at the tip 15a. The position of the tracing stylus 17a of the detector 17 in the Y direction (horizontal direction perpendicular to the X direction) substantially coincides with the center line of the turntable 12 in the Y direction.

[0003] A table rotation type roundness measuring machine is constructed in this manner, and the work is measured by roughly aligning the center of the measurement part of the work with the rotation center of the turntable 12 (within the measurable range of the detector 17). The work is rotated, the work is rotated, the circumference of the work is measured, and the roundness is calculated from the measured data.

Further, since the detector 17 can be moved up and down by the Z table 24, the roundness can be measured at an arbitrary height of the work. This makes it possible to calculate a cylindrical shape such as coaxiality or cylindricity from the roundness data at each measurement section. Further, when the detector 17 is moved up and down without rotating the turntable 12, the straightness of the work in the X direction can be measured.

[0005]

However, when the Z table 24 moves in the Z direction, the Z table 24 fluctuates due to the movement accuracy of the Z guide 13. As a result, since the horizontal position of the detector is displaced, the following measurement errors occur when measuring coaxiality or cylindricity.

This is shown in FIG. To is a rotary table 1
2, the center of rotation, Co is the position of the detector 17 when the error of the motion accuracy 13a of the Z guide 13 is zero, and Lc is To to C
The distance to o, Ec and Ed are the X-direction errors of the motion accuracy 13a of the Z guide 13 at the vertical Zc and Zd positions, respectively, and Dc and Dd are the detectors 1 at the Zc and Zd positions, respectively.
The distance from the position 7 to the point where the tracing stylus 17a abuts on the workpiece is shown. Therefore, radii Rc and Rd at positions Zc and Zd on one generatrix Wc of the work W are expressed by the following equations. Rc = Lc-Dc-Ec Rd = Lc-Dd-Ed

The coaxiality is determined by the rotation center To of the rotary table 12.
The difference between the two positions in the example of FIG. Rc−Rd = (Dd−Dc) + (Ed−Ec) That is, the difference between the errors Ec and Ed of the motion accuracy 13a is directly added to the coaxiality error.

The present invention has been made in view of such circumstances, and when a plurality of cross sections of a work are measured by a table rotation type roundness measuring machine to obtain coaxiality or cylindricity, the Z guide 13 is used. It is an object of the present invention to provide a method capable of performing measurement without being affected by the motion accuracy 13a of the subject.

[0009]

According to the present invention, in order to achieve the above object, a detector holder 16 is provided in parallel with a detector holder 15 on a Z-table of a table rotation type roundness measuring machine.
And a second holder is provided in the detector holder 16 in a direction connecting the detection direction of the first detector (the detector 17 described in the related art) to the rotation center Tc of the rotary table 12. It is provided so as to face the center. And
The first measurement value detected by the first detector and the rotation table 1
2, the work is rotated by 180 ° and the average value with the measured value detected by the second detector is set as the measured value at that point of the work. In this way, even if there is an error in the movement accuracy 13a of the Z guide 13, the error in the movement accuracy is canceled by the average of the two measured values.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall view of an embodiment of a roundness measuring machine according to the present invention, and FIG. The basic configuration of the roundness measuring machine shown in FIG. 1 is the same as that described in the related art (FIG. 3). The difference from the prior art is that there are two detectors. That is, as shown in FIG. 1, a detector holder 16 is provided on the Z table 14 on the upper side in parallel with the detector holder 15. A detector 17 is attached to the detector holder 15 as before, and a detector 18 (second detector) is provided to the detector holder 16. The detection direction of the detector 18 is set in a direction connecting the detection direction of the detector 17 and the rotation center To of the turntable 12 and facing the turntable 12.

The roundness measuring device according to the present invention is configured as described above. In a state where the work W is placed on the rotary table 12 and fixed, the rotary table 12 is driven to measure the workpiece. After roughly adjusting the center to the rotation center of the detectors 17 and 18 (within the measurable range of the detectors 17 and 18), the rotation table 12 is rotated to measure the circumference of the workpiece W. Then, after each point of the work is detected by the detector 17, it is rotated by 180 ° and detected by the detector 18, so that the first measurement value detected by the detector 17 and the measurement value detected by the detector 18 are obtained. An average value is calculated with the value (detected after the first measurement value by the rotation time of 180 ° of the rotation table 12), and the average value is set as the measurement value (radius) at that point of the work.

This will be described below with reference to FIG. In FIG. 2, To is the rotation center of the turntable 12, Ca and Cb are the positions of the detectors 17 and 18 when the error of the motion accuracy 13 a of the Z guide 13 is zero, La,
Lb is the distance from To to Ca and Cb, respectively, Ea is the X direction error of the motion accuracy 13a of the Z guide 13 at the vertical Za position, and Da is the contact of the tracing stylus 17a from the position of the detector 17 at the Z position. Db to the point
Represents the distance from the position of the detector 18 at the Z position to the point where the tracing stylus 18a contacts the workpiece. In FIG. 2, one generatrix Wa of the workpiece W is indicated by a solid line on the detector 17 side, and a state where the generatrix Wa is rotated by 180 ° and positioned on the detector 18 is expressed by an imaginary line as Wb.

In FIG. 2, one bus Wa of a workpiece W is shown.
The radius Ra at the Z position and the radius Rb when the bus Wa is rotated by 180 ° are expressed by the following equations. Ra = La−Da−Ea Rb = Lb−Db + Ea Therefore, the calculated measurement value is (Ra + Rb) / 2 = (La + Lb−Da−Db) / 2, and the error Ea of the motion accuracy 13a of the Z guide 13 is cancelled. Is done.

In the above-described embodiment, the directions of the two detectors 17 and 18 are set to the X direction. However, the present invention is not limited to this, and the moving directions of the detector holders 15 and 16 are changed to other directions. Also, the present invention can be applied. That is, it is only necessary that the detection directions of the two detectors 17 and 18 face the rotation center To of the turntable 12.

[0015]

As described above, according to the present invention, in a table rotation type roundness measuring machine, two
The two detector holders are provided, and the detectors are provided in the detector holders in such a manner that their detection directions are opposed to the rotation center of the rotary table. Then, the first measured value detected by the first detector and the worktable are determined by the rotation table.
The average value with the measured value detected by the second detector after rotating by 0 ° was set as the measured value (radius) at that point of the work. Thereby, the Z table which guides the Z table in the vertical direction is provided.
Even if there is an error in the movement accuracy of the guide in the horizontal direction, the error in the movement accuracy is canceled by the average of the two measured values. Therefore, measurement of the coaxiality and cylindricity without being affected by the movement accuracy of the Z guide. It can be carried out.

[Brief description of the drawings]

FIG. 1 is an external view of a roundness measuring machine according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of measurement of an embodiment of a roundness measuring machine according to the present invention.

FIG. 3 is an external view of a conventional roundness measuring device.

FIG. 4 is a diagram illustrating the measurement of a conventional roundness measuring machine.

[Explanation of symbols]

 W ... Work 11 ... Base 12 ... Rotary table 13 ... Z guide 14 ... Z table 15 ... Detector holder 16 ... Detector holder 17 ... Detector 18 ... Detector 17a ... Measuring element 18a ... Probe

Claims (1)

[Claims] A rotary table supported on a base so as to be rotatable around a vertical axis; a Z table supported on a Z guide erected on the base so as to be movable in a vertical direction; and a rotation center of the rotary table. And a first detector and a second detector provided on the Z table in a state of facing each other. The first measurement value detected by the first detector and the work
A roundness measuring device characterized in that an average value of the measured values detected by the second detector after being rotated by 80 ° is a measured value at that point of the work.