JPH06300559A - Aligning method and device for measurement object in roundness measurement instrument - Google Patents

Abstract

PURPOSE:To ensure an easy work for aligning the rotating center of a turntable with the center of a measurement object. CONSTITUTION:The forward end 13 of a probe 13 is made to copy the external surface of a measurement object 20 placed on the upper surface of a turntable 2, and the shape of the external surface is obtained with a computing element 22. The shape of the external surface and the center point thereof are indicated on a display screen 23, together with the rotating center of the turntable 2. An X-axis direction knob 17 and a Y-axis direction knob 18 as the accessory of the turntable 2 are operated, thereby aligning the center point of the external surface with the rotating center of the turntable 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The method and apparatus for centering an object to be measured in a circularity measuring device according to the present invention are used to measure the circularity of the surface of various articles to be measured. It is used to align the center of rotation of the turntable that constitutes the degree measuring device with the center of the object to be measured.

[0002]

2. Description of the Related Art Conventionally, roundness measuring instruments as shown in FIGS. 8 to 9 have been used to measure the roundness of the surface of various objects to be measured such as a rotating shaft. In this roundness measuring instrument, a turntable 2 that rotates about a vertical axis is provided on one side of an upper surface of a base 1 (on the left side in FIG. 8). This turntable 2
The horizontal position adjusting knobs 3 and 3 and the tilt adjusting knobs 4 and 4 are provided on the outer peripheral surface of the. By these knobs 3 and 4, the horizontal position and the tilt direction of the mounting table 5 for mounting the measured object can be finely adjusted. Such a turntable 2 is rotatably driven by a rotative driving device which is built in the base 1 and includes a motor. Further, the rotation angle of the turntable 2 by the rotation driving device is detected by an encoder (not shown) and is also sent to an arithmetic unit (not shown) as an angle signal.

On the other hand, the base end portion of a column 6 is fixed to the other side of the upper surface of the base 1 (right side in FIG. 8), and the column 6 is arranged in the vertical direction. Then, the slider 7 is attached to the column 6.
Is supported so that it can be raised and lowered. The slider 7 is raised and lowered manually or by a built-in motor.
Further, the slider 7 supports the support arm 8 in the horizontal direction. The support arm 8 can be displaced in the horizontal direction by a motor built in the slider 7.

A base end portion (lower end portion in FIG. 8) of the connecting arm 9 is fixedly connected to one end portion (left end portion in FIG. 8) of the support arm 8. That is, while the support pin protruding from one end surface of the support arm 8 is inserted into the circular hole formed at the base end of the coupling arm 9, the set screw 10 provided at the base end is tightened. The coupling arm 9 is coupled and fixed to one end of the support arm 8.

Further, the base end portion (the right end portion in FIG. 8) of the detector 11 is joined and fixed to the tip end portion (upper end portion in FIG. 8) of the joint arm 9 by tightening another set screw 12. ing. Then, the base end portion (upper end portion in FIG. 8) of the probe 13 is pivotally supported on the tip end portion (left end portion in FIG. 8) of the detector 11. The measuring element 13 has a tip portion 13 by a spring (not shown).
Elasticity is applied in the direction of pressing a against the surface of the object to be measured (clockwise direction in FIG. 8). Further, the tracing stylus 13 displaces the core of the differential transformer built in the detector 11 according to the swing, and directs a detection signal according to the swing amount from the detector 11 to the computing unit. I try to send it out.

When the roundness of the outer peripheral surface of the object to be measured is measured by the circularity measuring device constructed as described above, the object to be measured is placed at the center of the upper surface of the mounting table 5 constituting the turntable 2. And the tip portion 13a of the probe 13 is elastically pressed against the outer peripheral surface of the object to be measured. When the turntable 2 is rotated in this state, the tip portion 13a follows the outer peripheral surface of the measured object. In this state,
In addition to the detection signal, the angle signal is sent. Then, this computing unit obtains the shape of the outer peripheral surface of the object to be measured based on these signals.

By the way, when the shape of the outer peripheral surface of the object to be measured is obtained by the circularity measuring device constructed as described above and the circularity is measured, the rotation center of the turntable 2 and the object to be measured are measured. It is necessary to match the center as much as possible in order to reduce the measurement error. Therefore, conventionally, a concentric circle is formed on the upper surface of the mounting table 5 to facilitate the work of mounting the object to be measured on the central portion of the upper surface of the mounting table 5.

Further, a meter 14 as shown in FIG. 10 is provided on the control panel, and the pointer 15 of the meter 14 is swung in accordance with the signal sent from the detector 11. The deflection amount of the pointer 15 becomes smaller as the deviation between the center of rotation and the center of the object to be measured becomes smaller. Therefore, the operator moves the object to be measured in the diametrical direction on the upper surface of the mounting table 5 so that the touch of the pointer 15 becomes small.

[0009]

However, in the case of the method of causing the center of the object to be measured and the center of rotation of the turntable 2 to coincide with each other by the deflection of the pointer 15, the work is troublesome and requires skill, and it takes considerable time to make them coincide with each other. It was unavoidable that it took time.

That is, since the direction in which the pointer 15 swings and the direction in which the horizontal position adjusting knobs 3 and 3 should be rotated are not associated with each other, the object to be measured cannot be moved in the correct direction based on the swing of the pointer 15. It was difficult and inevitably required considerable skill to complete the alignment work in a short time.

Further, the detector 1 based on the oscillation of the probe 13
The measurement range of 1 is narrow (for example, about ± 1 mm), and when the deviation between the rotation center of the turntable 2 and the center of the object to be measured exceeds this measurement range, even if the turntable 2 rotates, the pointer above Since 15 does not swing, the above-mentioned centering work becomes more difficult.

The method and apparatus for centering the object to be measured in the roundness measuring instrument of the present invention have been invented in view of the above circumstances.

[0013]

A method and apparatus for centering an object to be measured in a roundness measuring instrument according to the present invention, wherein:
The method and apparatus described in 3 includes a turntable that rotates about a vertical axis, an encoder that detects a rotation angle of the turntable and outputs an angle signal, and a horizontal movement on the upper surface of the turntable. A mounting table that is freely supported; a first horizontal movement knob that moves the mounting table with respect to the turntable in a first horizontal direction; Second horizontal movement knob to move in the second horizontal direction at right angles to the horizontal direction, and a probe that follows the outer peripheral surface of the object to be measured placed on the top surface of the mounting table, and the displacement of this probe A roundness measuring instrument equipped with a detector that outputs a detection signal based on the detection signal, and a calculator that determines the outer peripheral shape of the object to be measured based on the detection signal and the angle signal sent from the detector. Ahead What is intended to match the center of the rotation center and the measuring object of the turntable.

Further, in the centering method of the object to be measured in the roundness measuring device described in claim 1, the center of the object to be measured is obtained by the arithmetic unit based on the outer peripheral shape, After displaying this center together with the center of rotation on the display screen, the first and second centers of rotation of the object to be measured and the center of rotation displayed on the display screen based on the operation of the second horizontal movement knob. By making them coincide with each other, the center of the object to be measured placed on the upper surface of the placing table and the center of rotation are made to coincide with each other.

In the roundness measuring device according to the third aspect of the present invention, the roundness measuring device has a display screen, and the computing device is the above roundness measuring device. Obtaining the center of the object to be measured based on the outer peripheral shape, the function of displaying this center together with the rotation center on the display screen, and the first and second horizontal movement knobs based on the operation table described above. When moved in the horizontal direction, the center of the object to be measured displayed on the display screen is matched to the moving direction of the mounting table by the amount of movement of the mounting table based on the operation of each horizontal movement knob. It has the function of moving in the direction.

On the other hand, the method and apparatus for centering an object to be measured in a roundness measuring instrument according to claims 2 and 4 are: a turntable which rotates about a vertical axis and a rotation angle of the turntable. Of the encoder, which outputs the angle signal as an angle signal, the mounting table supported on the upper surface of the turntable so as to be movable in the horizontal direction, and the mounting table which is moved in the first horizontal direction with respect to the turntable. A first horizontal movement knob for moving, and a second horizontal movement knob for moving the mounting table with respect to the turntable in a second horizontal direction perpendicular to the first horizontal direction, and a diameter of the turntable. A support arm movably arranged over the length direction in a state where the direction and the length direction thereof are matched, a displacement device for displacing the support arm in the length direction, and an upper surface of the mounting table described above. Placed A measuring element to follow the outer peripheral surface of the workpiece,
A detector that is supported by the end of the support arm and that outputs a detection signal based on the displacement of the probe, and an outer peripheral shape of the measured object based on the detection signal and the angle signal sent from the detector. The center of rotation of the turntable and the center of the object to be measured are made to coincide with each other prior to the measurement work by the roundness measuring device provided with a computing unit for determining.

Further, in the centering method of the object to be measured in the roundness measuring device according to the second aspect, the turn is performed while displacing the support arm so that the detection signal becomes substantially constant. Based on the displacement amount of the support arm and the angle signal when the table is rotated, the peripheral shape of the object to be measured is obtained by the calculator, and the object to be measured is further calculated based on the peripheral shape by the calculator. The center of the, and after displaying this center on the display screen together with the center of rotation, the first, the center of the DUT displayed on the display screen based on the operation of the second horizontal movement knob By making the center of rotation coincide with the center of rotation of the object to be measured placed on the upper surface of the mounting table.

Further, in the centering device for the object to be measured in the roundness measuring device described in claim 4, the roundness measuring device has a display screen, and the computing unit detects When the turntable is rotated while displacing the support arm so that the signal becomes substantially constant, the outer peripheral shape of the object to be measured is determined based on the displacement amount of the support arm and the angle signal,
Furthermore, the center of the object to be measured is determined based on the outer peripheral shape, and the function of displaying the center together with the center of rotation on the display screen and the operation of the first and second horizontal movement knobs are described above. When the table is moved in the horizontal direction, the center of the object to be measured displayed on the display screen is moved by the amount of movement of the table based on the operation of each of the horizontal movement knobs, the moving direction of the table. It has a function of moving in a direction suitable for.

[0019]

According to the centering device for the object to be measured in the roundness measuring instrument of the present invention configured as described above, the horizontal moving knob attached to the turntable can be rotated while watching the display screen. , The center of rotation of the turntable and the center of the object to be measured can be easily matched.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows a roundness measuring instrument incorporating the centering device of the present invention. The turntable 2 rotates about a vertical axis a by a motor (not shown) or manually. An encoder 16 provided concentrically with the turntable 2 detects the rotation angle of the turntable 2 and outputs it as an angle signal to a calculator 22 (microcomputer).

On the upper surface of the turntable 2, a mounting table 5 is provided.
However, it is movably supported in the horizontal direction. The mounting table 5 includes a first horizontal movement knob 17 which is an X-axis direction knob 17.
And the Y-axis direction knob 18, which is the second horizontal movement knob, are perpendicular to the turntable 2 in the X-axis direction, which is the first horizontal direction, and the Y, which is the second horizontal direction. It is movable in the axial direction. As shown in FIG. 1 and FIGS. 8 and 9, the turntable 2 is provided with tilt adjusting knobs 4 and 4 so that the tilt angle of the upper surface of the mounting table 5 can be finely adjusted. Based on the operation of the tilt adjusting knobs 4 and 4, the mounting table 5 swings above the upper surface of the mounting table 5 about a point O on the center of rotation of the turntable 2. The horizontal position and tilt angle adjusting mechanism is the same as the conventionally known mechanism, and therefore detailed description thereof is omitted.

The detector 11 is supported on the end of the support arm 8. The support arm 8 is movably arranged in the lengthwise direction in a state where the diameter direction of the turntable 2 and the lengthwise direction of the turntable 2 are aligned with each other. A displacement device 19 is attached to the support arm 8, and the displacement device 19 displaces the support arm 8 in the length direction thereof based on a command signal from the controller 26.

The detector 11 also has a measuring element 13. The tip portion 13a of the probe 13 is elastically pressed against the outer peripheral surface of the object 20 to be measured. Therefore, when the turntable 2 on which the object to be measured 20 is placed is rotated, the tip portion 13a follows the outer peripheral surface of the object to be measured 20, and the detector 11 sends out a detection signal according to the shape of the outer peripheral surface. . This detection signal is sent to the arithmetic unit 22 via the A / D converter 21. The calculator 22 has a function of obtaining the outer peripheral shape of the object to be measured 20 based on the detection signal and the angle signal sent from the encoder 16.

Although the above-described structure is also equipped with the conventionally known roundness measuring device, a display screen 23 is further provided in the centering device for the object to be measured of the present invention. At the same time, a new function is added to the arithmetic unit 22. That is, the arithmetic unit 22 has the following functions.

The first function of obtaining the center of the object 20 to be measured based on the outer peripheral shape obtained based on the detection signal and the angle signal and displaying the center together with the rotation center on the display screen 23. .

When the mounting table 5 is moved in the horizontal direction based on the operation of the X-axis direction knob 17 and the Y-axis direction knob 18, the object 20 to be measured displayed on the display screen 23 is displayed. A second function of moving the center in a direction commensurate with the moving direction of the mounting table 5 by the moving amount of the mounting table 5 based on the operation of the knobs 17 and 18.

The turntable 2 is displaced while the support arm 8 is displaced by the displacement device 19 so that the detection signal sent from the detector 11 to the calculator 22 via the A / D converter 21 becomes substantially constant. While rotating, the outer peripheral shape of the DUT 20 is obtained based on the displacement amount of the support arm 8 and the angle signal sent from the encoder 16 during this rotation, and further based on this outer peripheral shape. A third function of obtaining the center of the object 20 to be measured and displaying the center together with the rotation center of the turntable 2 on the display screen 23.

DUT 2 displayed on the display screen 23
The tip portion 13 of the probe 13 corresponding to the outer peripheral shape of 0
A fourth function of displaying the contact position of a and rotating the display of the contact position in response to the rotation of the turntable 2.

The center of rotation of the turntable 2 and the center of the object to be measured 20 are adjusted by the centering device for the object to be measured having the arithmetic unit 22 having the first to fourth functions as described above and the display screen 23. When aligning with each other, the following two methods are selected and performed according to the magnitude of the deviation between the centers.

First, when the deviation between the above two centers is small and is within the measuring range of the detector 11 (within ± 1 mm),
Without displacing the support arm 8, the position of the detector 11 is fixed and the tip portion 1 of the probe 13 is fixed.
The turntable 2 is rotated while the outer peripheral surface of the object 20 to be measured is in contact with 3a.

By the above-mentioned operation, the detection signal representing the unevenness of the outer peripheral surface of the object to be measured 20 and the angle signal representing the rotation angle of the turntable 2 are sent to the computing unit 22,
The calculator 22 obtains the outer peripheral shape of the device under test 20 based on these signals. Then, the center of the object to be measured 20 is obtained based on the outer peripheral shape obtained in this way. The process of obtaining the center from the outer peripheral shape is performed by a conventionally known arithmetic process such as the least square center method.

The center O of the object 20 to be measured thus obtained
Based on the first function, ₂₀ is a display screen 2 together with the rotation center O ₂ of the turntable 2 as shown in FIG.
3 Display on top. Since the rotation center O ₂ does not move, it is always displayed on the display screen 23 as an intersection of the X axis and the Y axis. On the display screen 23, based on the fourth function, in addition to these centers O ₂₀ and O ₂ ,
The mark 24 at the abutting position of the tip portion 13a of No. 3 is displayed corresponding to the outer peripheral shape of the measured object 20 displayed on the display screen 23.

In this way, when the centers O ₂₀ , O _{2 and the} mark 24 are displayed on the display screen 23, the centers O ₂₀ , O ₂ are matched based on these displays. In this way, the operation of aligning the centers O ₂₀ and O ₂ with each other is performed regardless of the position of the mark 24.
Also, it can be performed by rotating the Y-axis direction knob 18 in an appropriate direction, but here, a method for eliminating the Y-axis direction deviation and then the X-axis direction deviation will be described.

First, the mark 24 is moved on the Y axis by rotating the turntable 2 electrically or manually. As a result, as shown in FIG. 3, the tracing stylus 13 and the Y-axis direction knob 18 make the rotation center O ₂
The state exists in a position symmetrical about 180 degrees with respect to. Therefore, in this state, the Y-axis direction knob 18 is rotated in an appropriate direction to move the mounting table 5 in the Y-axis direction. At this time, on the basis of the second feature, the display center O ₂₀ of the screen 23, since the movement amount of the mounting table 5 is moved in the Y-axis direction, the center O _20, a chain line in FIG. 4 If the center O ₂₀ is moved from the state to the solid line state and the center O ₂₀ is aligned with the X axis, the deviation in the Y axis direction is eliminated.

When the displacement in the Y-axis direction is eliminated in this way, the turntable 2 is rotated by 90 degrees, and the turntable 2 shown in FIG.
As shown in, the probe 13 and the X-axis direction knob 17 are
It is made to exist at a position approximately 180 degrees symmetrical with respect to the rotation center O ₂ . Therefore, in this state, the X-axis direction knob 17 is rotated in an appropriate direction to move the mounting table 5 in the X-axis direction. At this time, based on the second function,
Since the center O ₂₀ on the display screen 23 is moved by the amount of movement of the mounting table 5 in the X-axis direction, the center O _20,
From the solid line state in FIG. 6 to the chain line state, the center O
_{If 20} is matched with the Y-axis, the deviation in the X-axis direction will be eliminated,
Center O of the object to be measured 20 placed on the upper surface of the table 5
₂₀ and the rotation center O ₂ of the turntable 2 is matched state.

Next, when the deviation between the centers O ₂ and O ₂₀ is large and exceeds the measurement range of the detector 11,
In order that the detection signal sent from the detector 11 to the arithmetic unit 22 via the A / D converter 21 becomes substantially constant,
While displacing the support arm 8 by the displacement device 19,
The turntable 2 is rotated. At this time, based on the third function, the computing unit 22 uses the angle signal representing the rotation angle of the turntable 2 and the displacement signal representing the displacement amount of the support arm 8 to determine the outer circumference of the DUT 20. The shape is obtained, and further the center O _{20 of the} object 20 to be measured is obtained, and this center O ₂₀ is displayed together with the rotation center O ₂ on the display screen 23 shown in FIG. The outer peripheral surface shape obtained from the displacement amount of the support arm 8 is rougher (inferior in accuracy) than the outer peripheral surface shape obtained based on the swing of the tracing stylus 13. Therefore, in the illustrated embodiment, the outer peripheral surface shape obtained from the displacement amount of the support arm 8 is displayed on the auxiliary display unit 25 provided at one corner of the display screen 23 on the X axis, the Y axis, the center O ₂₀ , and the rotation. Center O
_{2. The} mark 24a indicating the contact position of the tip portion 13a of the probe 13 is also displayed.

In this way, the outer peripheral surface shape is changed to the X-axis, Y-axis,
The auxiliary display unit 2 together with the center O ₂₀ , the rotation center O ₂ , and the mark 24a indicating the contact position of the tip end 13a of the probe 13.
5, when the X-axis direction knob 17 and the Y-axis direction knob 18 are operated based on the display of the auxiliary display section 25, the center of the measured object displayed on the auxiliary display section 25 is displayed. The O ₂₀ and the rotation center O ₂ are matched. The operation at this time is the same as the above-mentioned case where the displacement between the centers O ₂₀ and O ₂ is small. In addition, each of the above-mentioned knobs 17 and 1
Since the amount of movement of the mounting table 5 by 8 is about ± 5 mm, it is possible to perform centering unless the deviation between the centers is too large.

The accuracy of the centering performed in this way is lower than the accuracy of the centering performed based on the swing of the probe 13 as described above. Therefore, if a more accurate alignment is required, the alignment based on the swing of the probe 13 as described above is repeated.

Further, when the center line of the object 20 to be measured is inclined with respect to the vertical line a which is the rotation center O ₂ of the turntable 2, centering is performed at two positions above and below the object 20 to be measured. By doing so, the above inclination can be eliminated. That is,
As shown in FIG. 7, the outer peripheral shape of the lower part of the object to be measured 20 placed on the turntable 2 around the swing center O of the mounting table 5 is obtained, and the knobs 17 and Y in the X-axis direction are obtained. The axial knob 18 aligns this portion. Next, the shape of the outer peripheral surface of the upper portion of the object to be measured 20 is obtained, and the upper portion is aligned with the tilt adjusting knobs 4 and 4 (FIGS. 1, 8 and 9). As a result, the center O ₂ of the center O ₂₀ and the turntable 2 of the measurement object 20 coincide completely.

[0040]

The method and apparatus for centering an object to be measured in the roundness measuring instrument of the present invention is constructed and operates as described above, and therefore, it does not require special skill, and the center of the object to be measured is not required. The work of matching the rotation center of the turntable with that of the turntable can be performed easily and in a short time.

[Brief description of drawings]

FIG. 1 is a block diagram schematically showing an embodiment of the present invention.

FIG. 2 is a front view of a display screen.

FIG. 3 is a plan view of a turntable portion showing the positional relationship of each portion when eliminating the deviation in the Y-axis direction.

FIG. 4 is a diagram showing a display screen when eliminating a shift in the Y-axis direction.

FIG. 5 is a plan view of a turntable portion showing a positional relationship of each portion when eliminating the displacement in the X-axis direction.

FIG. 6 is a diagram showing a display screen when eliminating a shift in the X-axis direction.

FIG. 7 is a front view of a turntable and an object to be measured for explaining a state where the inclination of the object to be measured is corrected.

FIG. 8 is a front view showing an example of a roundness measuring device which is an object of the present invention.

FIG. 9 is a plan view of a turntable.

FIG. 10 is a front view of a conventionally used centering meter.

[Explanation of symbols]

 1 Base 2 Turntable 3 Horizontal Position Adjustment Knob 4 Tilt Adjustment Knob 5 Mounting Table 6 Strut 7 Slider 8 Support Arm 9 Coupling Arm 10 Set Screw 11 Detector 12 Set Screw 13 Measuring Point 13a Tip 14 Meter 15 Pointer 16 Encoder 17 X-axis direction knob 18 Y-axis direction knob 19 Displacement position 20 Object to be measured 21 A / D converter 22 Arithmetic unit 23 Display screen 24, 24a mark 25 Auxiliary display section 26 Controller

Claims (4)

[Claims] 1. A turntable which rotates about a vertical axis, an encoder which detects a rotation angle of the turntable and outputs it as an angle signal, and an upper surface of the turntable which is movably supported in a horizontal direction. A mounting table and a first horizontal movement knob for moving the mounting table with respect to the turntable in a first horizontal direction, and a mounting table described above with respect to the turntable at a right angle to the first horizontal direction. Such a second horizontal movement knob for moving in the second horizontal direction, a probe that follows the outer peripheral surface of the object to be measured placed on the upper surface of the mounting table, and a detection signal based on the displacement of the probe. Prior to the measurement work by the roundness measuring instrument provided with a detector for outputting, a detection signal sent out from this detector and the angle signal based on the angle signal, an arithmetic unit for determining the outer peripheral shape of the object to be measured, Tar A centering method of a measured object in a roundness measuring device, wherein the center of rotation of a rotary table and the center of the measured object are made coincident with each other. The center of the, and after displaying this center on the display screen together with the center of rotation, the first, the center of the DUT displayed on the display screen based on the operation of the second horizontal movement knob A method for centering an object to be measured in a roundness measuring instrument, wherein the center of the object to be measured placed on the upper surface of the mounting table and the center of rotation are matched by making the center of rotation coincide. 2. A turntable which rotates about a vertical axis, an encoder which detects a rotation angle of the turntable and outputs it as an angle signal, and an upper surface of the turntable which is movably supported in a horizontal direction. A mounting table and a first horizontal movement knob for moving the mounting table with respect to the turntable in a first horizontal direction, and a mounting table described above with respect to the turntable at a right angle to the first horizontal direction. A second horizontal movement knob for moving in the second horizontal direction, and a supporting arm movably arranged in the length direction in a state where the diameter direction of the turntable and the length direction thereof are matched. , A displacement device for displacing the support arm in its longitudinal direction, a tracing stylus that follows the outer peripheral surface of the object to be measured placed on the upper surface of the mounting table, and supported by the end portion of the support arm,
A detector that outputs a detection signal based on the displacement of the probe,
The center of rotation of the turntable prior to the measurement work by the roundness measuring instrument provided with a computing unit for determining the outer peripheral shape of the object to be measured based on the detection signal sent from this detector and the angle signal. And a center of the object to be measured, which is a method of aligning the object to be measured in a roundness measuring device, wherein the supporting arm is displaced so that the detection signal becomes substantially constant. Based on the displacement amount of the support arm and the angle signal when rotating the table,
After obtaining the outer peripheral shape of the object to be measured by the arithmetic unit, further obtaining the center of the object to be measured based on the outer peripheral shape by the arithmetic unit, and displaying the center together with the rotation center on the display screen, By making the center of rotation and the center of rotation of the measured object displayed on the display screen coincide with each other based on the operation of the first and second horizontal movement knobs, the object placed on the upper surface of the placing table is placed. A centering method for an object to be measured in a circularity measuring instrument, which aligns the center of the object with the center of rotation. 3. A turntable which rotates about a vertical axis, an encoder which detects a rotation angle of the turntable and outputs it as an angle signal, and an upper surface of the turntable which is movably supported in a horizontal direction. A mounting table and a first horizontal movement knob for moving the mounting table with respect to the turntable in a first horizontal direction, and a mounting table described above with respect to the turntable at a right angle to the first horizontal direction. Such a second horizontal movement knob for moving in the second horizontal direction, a probe that follows the outer peripheral surface of the object to be measured placed on the upper surface of the mounting table, and a detection signal based on the displacement of the probe. Prior to the measurement work by the roundness measuring instrument provided with a detector for outputting, a detection signal sent out from this detector and the angle signal based on the angle signal, an arithmetic unit for determining the outer peripheral shape of the object to be measured, Tar A centering device for measuring an object to be measured in a circularity measuring device, wherein the center of rotation of a rotary table and the center of the object to be measured are aligned, the circularity measuring device having a display screen, The computing unit obtains the center of the object to be measured based on the outer peripheral shape, displays the center together with the rotation center on the display screen, and based on the operations of the first and second horizontal movement knobs. When the table is moved in the horizontal direction, the center of the object to be measured displayed on the display screen is moved by the amount of movement of the table based on the operation of the horizontal movement knobs. A centering device for an object to be measured in a roundness measuring instrument, which has a function of moving the object in a direction corresponding to the moving direction of the object. 4. A turntable which rotates about a vertical axis, an encoder which detects a rotation angle of the turntable and outputs it as an angle signal, and an upper surface of the turntable which is movably supported in a horizontal direction. A mounting table and a first horizontal movement knob for moving the mounting table with respect to the turntable in a first horizontal direction, and a mounting table described above with respect to the turntable at a right angle to the first horizontal direction. A second horizontal movement knob for moving in the second horizontal direction, and a supporting arm movably arranged in the length direction in a state where the diameter direction of the turntable and the length direction thereof are matched. , A displacement device for displacing the support arm in its longitudinal direction, a tracing stylus that follows the outer peripheral surface of the object to be measured placed on the upper surface of the mounting table, and supported by the end portion of the support arm,
A detector that outputs a detection signal based on the displacement of the probe,
The center of rotation of the turntable prior to the measurement work by the roundness measuring instrument provided with a computing unit for determining the outer peripheral shape of the object to be measured based on the detection signal sent from this detector and the angle signal. And a center of the object to be measured in the circularity measuring device, wherein the circularity measuring device has a display screen and the arithmetic unit detects While displacing the support arm so that the signal becomes substantially constant, the outer peripheral shape of the object to be measured is obtained based on the displacement amount of the support arm and the angle signal when the turntable is rotated. Based on the outer peripheral shape, the center of the object to be measured is obtained, and further the function of displaying the center on the display screen together with the center of rotation and the operation of the first and second horizontal movement knobs are used. If you move the The function of moving the center of the object to be measured displayed on the display screen in a direction commensurate with the moving direction of the mounting table by the amount of movement of the mounting table based on the operation of the horizontal movement knobs. A centering device for an object to be measured in a roundness measuring instrument.