JPH0682247A - Method and apparatus for measuring outline shape - Google Patents

Abstract

PURPOSE:To measure the outline shape of a bar-shaped body as a whole at high accuracy. CONSTITUTION:Two outline detecting sections comprising projecting sections 2 and 2' and receiving sections 3 and 3' are provided to measure the outline shape of the cross section of a subject 1 as bar-shaped body and the outline detecting sections are provided with a driving mechanism to move on a rail 4 in the axial direction of the subject 1. The subject 1 is held at both ends thereof by chucking devices 5 and 5 and rotation axis detection discs 6 and 6 made round and rotating devices 7 and 7 are linked to the outside thereof. The object 1 and the rotation axis detecting discs 6 and 6 rotate with the rotating device 7 and 7 around the axis of the object 1. The rotation axis is determined from measured values of the rotation axis detection discs 6 and 6, thereby, calibrating the measured value of the object 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for capturing the contour of a rod-shaped body and measuring its outer shape, and an apparatus used for carrying out the method.

[0002]

2. Description of the Related Art Conventional external shape measurement over the entire rod-shaped body is performed by fixing a measuring device and rotating an object to be measured, or by fixing an object to be measured and rotating the measuring device. For example, in JP-A-52-119253, a light-transmissive optical system detection unit including a light-projecting unit and a light-receiving unit provided to measure a cross section perpendicular to the axial direction of an object to be measured is used. A device for measuring while rotating an object to be measured is disclosed. FIG. 7 is a perspective view showing this conventional external shape measuring apparatus. In the figure, 1 is a rod-shaped object to be measured, and rotating devices 17 and 1 are provided so as to sandwich both ends of the object to be measured 1 in the axial direction.
7 is installed. The rotating devices 17, 17 rotate the DUT 1 with the axial direction of the DUT 1 as a central axis.
In addition, in order to measure the outer shape of the cross section perpendicular to the axial direction of the DUT 1, two sets of outer shape detecting sections, each including a light emitting section 2, 2 ′ and a light receiving section 3, 3 ′ for parallel rays, are provided. The measurement directions are arranged so as to be orthogonal to each other. A truck is attached to the lower side of the light receiving section 3, and a rail 4 is arranged below the light receiving section 3 in parallel with the DUT 1. Two sets of outer shape detecting sections are covered by a driving device (not shown). The measurement object 1 is movable in the axial direction.

Further, a signal analysis section (not shown) for detecting the boundary between the bright and dark areas is connected to the light receiving sections 3 and 3'of the outer shape detecting section, and the drive unit 4 is provided with a position in the axial direction. Is connected to an axial position detecting unit (not shown), and the rotation device 7 is connected to a rotation angle detecting unit (not shown) for detecting a rotation angle.

In the apparatus having the above structure, parallel light rays are projected from the light projecting portions 2 and 2'perpendicular to the axial direction of the DUT 1 and the boundary between the bright and dark parts of the DUT 1 is received. Part 3,
Detect at 3 '. This is performed at a plurality of rotation angles, and the measurement values at each rotation angle are plotted on the same coordinates by expressing them in a two-dimensional coordinate system (the origin is arbitrary) with the orthogonal measurement directions as the X axis and the Y axis. When this measurement is continuously performed while moving the outer shape detecting portion in the axial direction of the DUT 1, three-dimensional measurement can be performed, and if the measured values are plotted in the same three-dimensional coordinate system, the DUT 1 as a whole is measured. The outer shape of can be measured.

In this case, in order to plot the measured values of the outer shape at the respective rotation angles on the same coordinates, it is necessary to correct the rotation angles. 8 and 9 are graphs for explaining this correction method. FIG. 8A is a plot of four measurement points A, B, C and D on the outer circumference of the cross section at the rotation angle θ on the XY coordinates. Point the projection in the Y-axis direction A, X coordinate X _a of B, X _b is obtained, the rotation of these center O (X _0, Y ₀₎ of the point giving Y coordinates A, B coordinates (X _a , Y ₀ ), (X _b , Y ₀ ), where (X _b <X ₀ <
X _a ). In addition, the Y coordinate Y of points C and D can be obtained by projecting light in the X-axis direction.
_c and Y _d are obtained, and X of the rotation center O (X ₀ , Y ₀ ) is obtained.
Given the coordinates, the coordinates (X ₀ , Y _c ), (X ₀ ,
Y _d) to _{(Y d <Y 0 <Y} c).

FIG. 8 (b) shows that each measurement point is rotated with the rotation angle θ.
Heart O (X₀, Y₀Rotation angle θ = 0 ° (measurement start position)
(A) is a graph represented by conversion into the coordinate system. Rotation angle θ
₁The coordinates of each measurement point A, B, C, D in
O (X₀, Y₀) Around θ₁On the rotated points A ', B', C ', D'
The coordinates are converted. This method is performed as follows.
It For example, the case of the measurement point A will be described. θ = 0 °
The coordinates of A in (X _a0, Y₀) And the coordinates of A '
(X_a1, Y_a1), These are related to
Become. At this time, the radius of gyration is r (r = X_a0-X₀)
It X_a1= X₀+ R · cos θ₁ Y_a1= Y₀+ R · sin θ₁ Figure 9 shows the above coordinate transformation for θ = 30 ° and 60 ° respectively.
Shape obtained by plotting in the coordinate system of θ = 0 °
It is an example of a measurement result. As described above, the value of the rotation center
Based on this, correct the external shape measurement value for each rotation angle and
Perform the whole operation continuously in the axial direction (Z-axis direction) of DUT 1.
All measurement results are converted into one XYZ coordinate system.
It

[0007]

However, when the position of the device itself changes due to temperature change, for example, when measuring a high-heat-producing object, the chucking mechanism of the object to be measured thermally expands to cause a change in the rotating shaft. If the central axis of the object to be measured does not match, an error occurs in the measurement value obtained by the coordinate conversion. In order to prevent this, there is a method of improving the performance of the rotating device itself so as to maintain a constant rotating shaft that does not change with time so that measurement of the rotating shaft is unnecessary, or a method of monitoring the rotating shaft by another measuring device. To be However, these methods cause problems such as an increase in size of the device and an increase in cost.

The present invention has been made in view of the above circumstances, and an external shape measuring method and its method that can accurately measure the external shape of an object to be measured by including a disc for detecting a rotation axis are provided. It is intended to provide a device used for implementation.

[0009]

According to a first aspect of the present invention, there is provided an outer shape measuring method for rotating a rod-shaped object to be measured around its axis or providing an outer shape detecting portion for detecting an outer shape around the object to be measured. The outer shape detecting section detects the outer shape of the cross section of the object to be measured, and the object to be measured or the outer shape detecting section is moved in the axial direction of the object to be measured to measure the entire shape of the object to be measured. In the method for measuring the outer shape, a plurality of disks for detecting the rotation axis of the object to be measured are provided concentrically with the object to be measured, and the outer shape of the disk is detected, and from this detection result The detection value of the object to be measured by the outer shape detection unit is calibrated based on the obtained value of the rotation axis.

According to a second aspect of the present invention, there is provided an outer shape measuring device for detecting the outer shape of a rod-shaped object to be measured, and rotating the object to be measured around its axis, or the outer shape detecting portion is provided with the outer shape detector. An outer shape measuring device comprising a rotating device that rotates around an object to be measured, and a drive mechanism that moves the object to be measured or the outer shape detection unit in an axial direction of the object to be measured, wherein a rotation axis of the object to be measured. A plurality of discs mounted orthogonally to the rotation axis for detecting the rotation center, means for calculating the rotation center of each disc based on the detection result of the outer shape detection unit, and rotation of each calculated disc. The rotation axis is 3 from the center
It is characterized by comprising means for dimensionally calculating and means for calibrating the detection value of the object to be measured by the outer shape detection unit based on the value of the rotation axis.

[0011]

In the present invention, the coordinates of the ends of two diameters orthogonal to each other of a plurality of discs connected to the rotating device are detected, the coordinates of the midpoint of these diameters are obtained, and the coordinates of a plurality of rotation angles are calculated. The measurement is performed, the coordinates of multiple midpoints are expressed in the same coordinate system, the center of coordinates of these multiple midpoints is determined as the center of rotation, and the multiple rotation centers obtained from multiple discs are connected to form the rotation axis. Since the measured value of the outer shape of the DUT is calibrated based on this rotation axis, the influence of the fluctuation of the rotation axis due to the thermal expansion of the rotating device due to the heat conduction and heat radiation from the measurement object is calculated. It can be removed and highly accurate measurement can be performed. Further, it is not necessary to set a dedicated measuring instrument for measuring the rotation axis.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 1 is a perspective view showing an implementation state of an external shape measuring method according to the present invention. In the figure, reference numeral 1 is a round bar-shaped object to be measured, and in order to measure the outer shape of a cross section perpendicular to the axial direction of the object to be measured 1, a parallel light beam projection unit 2, 2 ′ and a light receiving unit 3, 2 sets of 3D outer shape detector
The measurement directions are arranged so as to be orthogonal to each other.
A truck (not shown) is attached to the lower side of the light receiving unit 3, and a rail 4 is arranged below the light receiving unit 3 in parallel with the DUT 1. Two sets of rails are provided by a driving device (not shown). The outer shape detection unit is movable in the axial direction of the DUT 1.

Further, both ends of the object to be measured 1 in the longitudinal direction are detachably clamped by chucking devices 5 and 5, and a rotary shaft having an appropriate thickness is detected outside the chucking devices 5 and 5. The disks 6, 6 are concentrically connected to the DUT 1. Further, outside the rotary shaft detecting disks 6 and 6, the DUT 1, the chucking devices 5 and 5, and the rotary shaft detecting disks 6 and 6 are integrally formed with the substantially axis of the DUT 1 as a rotary shaft. Rotating devices 7 and 7 that are electrically rotated are connected. The rotary shaft detecting disks 6 and 6 are accurately formed into a perfect circle by a method such as cutting, and the diameter thereof is shorter than the maximum measurable diameter of the outer shape detecting portion. The rail 4 is, of course, the rotating shaft detecting disk 6,
6 is also a measurable length.

Further, a signal analysis unit 8 for detecting a boundary between a light portion and a dark portion is connected to the light receiving portions 3 and 3'of the outer shape detecting portion, and the rail 4, the carriage, and the driving device are axially positioned. Is provided with an axial position detector 9 using a digital scale, and the rotation device 7 is connected with a rotation angle detector 10 using a rotary encoder to detect a rotation angle.

In the device of the present invention having the above construction,
Similar to the conventional device, the parallel rays are projected from the light projecting units 2 and 2'perpendicular to the axial direction of the DUT 1 and the
The boundary of the dark part is detected by the light receiving parts 3 and 3 '. This is performed at a plurality of rotation angles, and the measurement directions orthogonal to each other are X-axis and Y-axis.
Expressed in a two-dimensional coordinate system with an axis (the origin is arbitrary), the measured values of each rotation angle are calibrated based on the coordinates of the rotation axis and plotted on the same coordinate. When this measurement is continuously performed while moving the outer shape detecting portion in the axial direction of the DUT 1, three-dimensional measurement can be performed, and if the measured values are plotted in the same three-dimensional coordinate system, the DUT 1 as a whole is measured. The outer shape of can be measured.

Next, a method of detecting the rotation axis will be described.
FIG. 2 is a schematic diagram for explaining a measurement portion of the rotation axis detecting disc 6. As shown in FIG. 2A, the X and Y axes are taken in parallel with the light receiving parts 3 and 3 ', and the Z axis is taken in the axial direction of the DUT 1. When parallel rays of light in the X-axis direction and the Y-axis direction are projected, the measurement points A, B, C, D at the two orthogonal diameter ends of the rotation axis detection disk 6 respectively become X, as shown in FIG. 2 (b). Points a and b on the axis
And at points c and d on the Y axis.

3 and 4 show the rotary shaft and the rotary shaft detecting disk 6.
Change in measured value due to rotation when the centers are not aligned
It is a graph for explaining. Fig. 3 shows the rotation axis detection disk
6 is rotated and the state is shown every 90 °. Figure
When the rotary shaft detecting disk 6 rotates as shown in 3, measurement points A,
The coordinates of B, C and D are changed each time. If θ = 0 °
The measured values of the measurement points A, B, C, D₁, B₁，
c₁, D₁And the measurement point A when θ = 90 °,
The measured values of B, C and D are a₂, B₂, C₂, D₂And θ
Measurement points A, B, C, D when = 180 °
Value a₃, B₃, C ₃, D₃And θ = 270 °
Measurement points A, B, C, D at _Four, B_Four，
c_Four, D_FourThen, for example, the rotation center at θ = 0 °
Are centered horizontally, these are
Get involved. a_Four<A₁= A₃<A₂ b_Four<B₁= B₃<B₂ c₁<C₂= C_Four<C₃ d₁<D₂= D_Four<D₃

FIG. 4 is a graph showing the relationship between the rotation angle θ and the measured values. FIG. 4A shows measured values a and b on the X axis, and FIG. 4B shows on the Y axis. The measured values c and d are shown. Since the rotating shaft detecting disk 6 has a perfect circular shape, the measured values a, b, c, d respectively fluctuate in a sine wave shape. At this time a
The midpoints X _ab and Y _cd of b and cd are X _ab = (a + b), respectively.
/ 2, Y _cd = (c + d) / 2. FIG. 5 is a plot of the above-mentioned midpoints on the XY coordinates for each rotation axis. Eight points are displayed when displayed at 45 ° pitch.
These points exist on a circle centered on the rotation center if the rotation axis detection disk 6 is a perfect circle (FIG. 5 (a)). Therefore, if a circle having the above eight points (X _ab , Y _cd ) on its circumference is determined, the center coordinates of the circle are the rotation center O in the measurement cross section.
(X ₀ , Y ₀ ) (FIG. 5 (b)). As the number of plotted points increases, the measurement accuracy of the rotation center improves.

In this way, the two rotary shaft detecting disks 6,
When the center of rotation is obtained for 6 and the coordinates (Z coordinates) Z ₁ and Z ₂ in the axial direction of the DUT 1 of these two rotational axis detection disks 6 and 6 given by the axial position detection unit 9 are given. XY
Rotation center O ₁ (X ₁ , Y ₁ , Z ₁ ) in the Z coordinate, O
₂ (X ₂ , Y ₂ , Z ₂ ) is obtained. By connecting these, it is possible to determine the rotation axis in three dimensions. FIG. 6 is a graph showing these rotation centers and rotation axes.

When measuring the outer shape of the DUT 1, the measurement is performed using one point on the determined rotation axis. That is, the rotation center in the measurement cross section (XY coordinate plane) is obtained from the coordinates of the rotation axis having the Z coordinate on which the arbitrary measurement cross section is located, and the rotation center O (X ₀ , Y ₀ ) is used to generate the above-mentioned FIG. 9
The coordinate of the measurement point at each rotation angle is calibrated to the coordinate system with the rotation angle θ = 0 ° by the method shown in FIG. 8 and 9 are graphs for explaining this calibration method. Fig. 8 (a) shows four measurement points A, B, C, D on the outer circumference of the cross section at the rotation angle θ as X.
It is plotted on the Y coordinate. Point the projection in the Y-axis direction A, X coordinate X _a of B, X _b is obtained, the rotation of these center O (X _0, Y ₀₎ of the point giving Y coordinates A, B coordinates (X _a , Y ₀ ), (X _b , Y ₀ ), where (X _b <X ₀ <
X _a ). In addition, the Y coordinate Y of points C and D can be obtained by projecting light in the X-axis direction.
_c and Y _d are obtained, and X of the rotation center O (X ₀ , Y ₀ ) is obtained.
Given the coordinates, the coordinates (X ₀ , Y _c ), (X ₀ ,
Y _d) to _{(Y d <Y 0 <Y} c).

FIG. 8 (b) shows that each measurement point is rotated with the rotation angle θ.
Heart O (X₀, Y₀Rotation angle θ = 0 ° (measurement start position)
(A) is a graph represented by conversion into the coordinate system. Rotation angle θ
₁The coordinates of each measurement point A, B, C, D in
O (X₀, Y₀) Around θ₁On the rotated points A ', B', C ', D'
The coordinates are converted. This method is performed as follows.
It For example, the case of the measurement point A will be described. θ = 0 °
The coordinates of A in (X _a0, Y₀) And the coordinates of A '
(X_a1, Y_a1), These are related to
Become. At this time, the radius of gyration is r (r = X_a0-X₀)
It X_a1= X₀+ R · cos θ₁ Y_a1= Y₀+ R · sin θ₁

FIG. 9 shows the above-mentioned coordinate conversion by θ = 30 °, 60 °
3 is an example of the outer shape measurement result obtained by carrying out each of the above and plotting in a coordinate system of θ = 0 °. As described above, based on the value of the rotation center, the outer shape measurement value for each rotation angle is calibrated, and this is continuously performed in the axial direction (Z-axis direction) of the DUT 1 to be measured. The measurement result is converted into one XYZ coordinate system. In FIG. 9, the measurement points for every 30 ° are plotted, but if this is subdivided, more accurate measurement is possible.

By configuring the measuring device or the object to be measured to be movable in the direction perpendicular to the plane of rotation of the rotating mechanism, it is possible to measure the outer shape at all positions of the object to be measured. Further, in the present embodiment, the two outer shape detection units are provided,
The number is not limited to two, and the larger the number, the higher the measurement accuracy. Further, in the present embodiment, the structure is such that the DUT and the rotation axis detecting disc are rotated, but the structure may be such that the DUT and the rotation axis detecting disc are fixed and the outer shape detecting unit is rotated. Further, as the outer shape detecting section, a distance sensor capable of detecting a three-dimensional position such as a laser distance meter, a capacitive displacement meter, a magnetic displacement meter or the like can be used.

[0024]

As described above, according to the present invention, the disk is measured simultaneously with the object to be measured, and the outer shape is measured using the rotary shaft obtained by the measurement of the disk. Highly accurate measurements can be performed by eliminating the effects of fluctuations in the rotating shaft caused by thermal expansion of the rotating device due to heat conduction and heat radiation from the object to be measured. Further, since it is not necessary to set a dedicated measuring instrument for measuring the rotation axis, the present invention has excellent effects such as high-accuracy measurement at low cost.

[Brief description of drawings]

FIG. 1 is a perspective view showing an implementation state of an external shape measuring method according to the present invention.

FIG. 2 is a schematic diagram for explaining a measurement portion of a rotation axis detecting disc in FIG.

FIG. 3 is a graph for explaining changes in measured values due to rotation when the center of the rotation axis does not coincide with the center of the rotation axis detection disk.

FIG. 4 is a graph for explaining changes in measured values due to rotation when the center of the rotation axis does not coincide with the center of the rotation axis detection disk.

FIG. 5 is a graph in which a midpoint of measurement points is plotted on XY coordinates for each rotation axis.

FIG. 6 is a graph showing two rotation center points and a rotation axis.

FIG. 7 is a perspective view showing an implementation state of a conventional external shape measuring method.

FIG. 8 is a graph for explaining a method of plotting measured values of an outer shape at respective rotation angles on the same coordinates.

FIG. 9 is a graph for explaining a method of plotting the measured values of the outer shape at each rotation angle on the same coordinates.

[Explanation of symbols]

 1 DUT 2 Light emitting part 3 Light receiving part 4 Rail 5 Chucking device 6 Rotation axis detection disk 7 Rotation device 8 Signal analysis part 9 Axial position detection part 10 Rotation angle detection part

Claims (2)

[Claims] 1. A rod-shaped object to be measured is rotated around its axis, or an outer shape detection unit for detecting an outer shape is rotated around the object to be measured, and the outer shape detection unit causes a cross section of the object to be measured. The outer shape of the object to be measured or the outer shape detecting unit is moved in the axial direction of the object to be measured to measure the outer shape of the entire object to be measured. A plurality of discs for detecting the object are provided concentrically with the object to be measured, the outer shape of the disc is detected, and the outer shape detection unit detects the outer shape based on the value of the rotation axis obtained from the detection result. An outer shape measuring method characterized by calibrating a detected value of a measured object. 2. An outer shape detecting unit for detecting an outer shape of a rod-shaped object to be measured, and rotation for rotating the object to be measured around its axis or rotating the outer shape detecting unit around the object to be measured. In an external shape measuring device comprising a device and a drive mechanism for moving the object to be measured or the external shape detection unit in the axial direction of the object to be measured, the rotary shaft for detecting the rotary shaft of the object to be measured. A plurality of discs mounted orthogonally to each other, a means for calculating the rotation center of each disc based on the detection result of the outer shape detection unit, and a three-dimensional rotation axis based on the calculated rotation center of each disc. And a means for calibrating the detected value of the object to be measured by the outer shape detection unit based on the value of the rotation axis.