JP2001159515A - Flatness measuring method and flatness measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flatness measuring method and a flatness measuring device capable of measuring precisely flatness of a work by eliminating a measurement error caused by thermal expansion of a measuring jig. SOLUTION: This device is equipped with a measuring mechanism 10 having at least four sensors D1-D4 in prescribed arrangement for measuring the distance to the work surface WS, an X-axis driving mechanism 20 for moving the measuring mechanism 10 in the X-axis direction and a Y-axis driving mechanism 30 for moving the mechanism 10 in the Y-axis direction, a driver 40 for driving the X-axis and Y-axis driving mechanisms 20, 30, and a controller 50 for controlling the driver 40, and for executing operation processing of a measured value from the measuring mechanism 10, to measure the flatness of the work surface WS. The measurement is executed based on the difference between the point corresponding to a fourth point on the plane formed by three points, namely, a first point, a second point and a third point, where measurement of the flatness is executed, and the fourth point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a flatness measuring method and a flatness measuring device. More specifically, the present invention relates to a flatness measuring method and a flatness measuring apparatus for measuring the flatness of a product which is required to have a highly accurate flat surface such as a surface plate.

[0002]

2. Description of the Related Art Conventionally, when manufacturing a product (hereinafter referred to as a work) requiring a high degree of flatness such as a surface plate, the flatness of the manufactured work is measured by, for example, a sampling inspection. Is usually the case. This is because it is not easy to perform temperature control in a normal factory. For this reason, when trying to measure the flatness of a product in a production line, the measuring jig expands and contracts with a change in temperature, thereby causing an error in the measurement result. Therefore, in order to avoid the influence of the measurement error due to the temperature change in the factory, the flatness of the work is measured in the inspection room where the temperature control is performed.

FIG. 7 shows an example of such a conventional flatness measuring method. In this example, the height from the reference position is measured by, for example, a dial gauge at eight measurement points E, three on each side of the rectangular plane F ′ of the surface plate. Then, by dividing the difference between the maximum value and the minimum value by an appropriate number, the flatness per 100 mm square of the plane F ′ is calculated.

As described above, conventionally, when inspecting the flatness of a work such as a surface plate, in order to eliminate the influence of an error due to a change in ambient temperature, a flat surface is inspected in an inspection room where temperature control is performed. It is usual to measure degrees.
For this reason, in order to inspect the flatness of the work, it is necessary to carry the work from the production line to the inspection room, and it is difficult to perform the inspection on all the works, and the inspection result is immediately fed back to the manufacturing process. There is a problem that it is difficult to perform appropriate measures such as reworking a workpiece having poor flatness according to the inspection result.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned problems in the prior art, and is intended to measure the flatness of a work by measuring a measurement error caused by thermal expansion of a measuring jig and a straightness error of a sensor driving unit. It is an object of the present invention to provide a flatness measuring method and a flatness measuring device which can be precisely measured without being removed.

[0006]

A flatness measuring method according to the present invention is a flatness measuring method for measuring flatness of a workpiece, wherein at least four points on a surface to be measured are simultaneously or almost simultaneously measured by a distance sensor. Is measured, and the measured value is appropriately processed to measure the flatness of the work.

In the flatness measuring method of the present invention, for example, the flatness is measured by measuring a fourth point on a plane formed by three points of the measured first point, second point and third point. This is performed based on the difference in distance between the point corresponding to the point and the fourth point. In this case, the first point, the second point, the third point, and the fourth point are arranged so as to form a square, and the difference between the point corresponding to the fourth point and the fourth point. May be set as the flatness of the surface to be measured.

On the other hand, a flatness measuring apparatus according to the present invention comprises a measuring mechanism having a predetermined arrangement of sensors for measuring a distance to a surface to be measured, a first driving mechanism for moving the measuring mechanism in one direction, and an orthogonal mechanism. A second drive mechanism for moving in a direction to be driven, a driver for driving the first drive mechanism and the second drive mechanism, and a plane for the surface to be measured by controlling the driver and arithmetically processing a measurement value from the measurement mechanism. A controller for measuring the degree.

In the flatness measuring apparatus of the present invention, it is preferable that the sensors are arranged so as to form a square.

[0010]

According to the present invention, the flatness of a work can be accurately measured irrespective of a change in ambient temperature, for example, even in a production line.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the accompanying drawings, but the present invention is not limited to only such embodiments.

FIG. 1 shows a configuration of a flatness measuring apparatus to which a flatness measuring method according to an embodiment of the present invention is applied. This flatness measuring apparatus A is, for example, a product such as a surface plate (hereinafter referred to as a work). ) It is arranged near the conveyor K that transports the work W so that the flatness of W can be measured in the production line.

The flatness measuring device A includes a measuring mechanism 10 for measuring a distance to the surface of the work W, and an X
X-axis drive mechanism (first drive mechanism) 20 driven in the axial direction
A Y-axis driving mechanism (second driving mechanism) 30 for driving in the Y-axis direction; an X / Y-axis driving driver 40 for supplying driving power to these driving mechanisms 20 and 30; A controller 50 that controls the driver 40 and performs arithmetic processing on the measurement value from the measurement mechanism 10.
Under the control of the controller 50, the measuring mechanism 10 is driven substantially parallel to the inspection surface WS of the workpiece W (see FIG. 2).
The flatness of the work W is measured.

As shown in FIG. 3, the measuring mechanism 10 has first to fourth distance sensors D _{1 to} D ₄ on a surface 11 of the work W opposite to the inspection surface WS. Each sensor D ₁ to D ₄ is the center of the sensor D ₁ ~D _{4, 1} side in the surface 11 is 100
It is arranged so that each vertex of the square 12 of mm may be comprised. Each of the distance sensors D _{1 to} D ₄ irradiates the workpiece W with, for example, a laser beam, detects the reflected light with an image sensor, and measures the distance from the laser beam irradiation angle to the measurement point at this time. It consists of a rangefinder. Further, a diaphragm method for measuring the distance by measuring the reflection time of ultrasonic waves, microwaves or light, or a method using binocular stereoscopic vision using two cameras may be used.

Next, with reference to FIG.
A flatness measurement method executed under the control of the controller 50 will be specifically described.

FIG. 4 shows the inspection surface WS of the work W. Workpiece W is long side W ₁ of the inspected surface WS of the rectangular is parallel to the X-axis direction in FIG. 1, also the short side W ₂ is 1 Y
It is placed parallel to the axial direction. In this state, each driving mechanism 20 is positioned so that, for example, the second sensor D ₂ is located vertically above a point P ₂ near one corner C of the inspection surface WS.
30 moves the measuring mechanism 10. by this,
First sensor D ₁ is located from the point P ₂ in the X-axis direction vertically above the point P ₁ of -100 mm, 100 from the point P ₂ in the Y-axis direction
with mm point vertically above the fourth sensor D ₄ P ₄ is positioned, the point P ₂ than -100mm in the X-axis direction, Y to vertically above the point P ₃ of 100mm axial third sensor D ₃ Is located.

Furthermore, by measuring the distance from the sensor D ₁ to D ₄ to the inspected surface WS at the same time in this state, the square inner area of the point _{P 1, P 2, P 3} , P 4 and vertices The flatness at R ₁ can be measured according to the principle described below.

As shown in FIG. 5, the ideal plane corresponding to the inspected surface WS to the XY plane, with the Z-axis passes through the point P _1, X-axis direction and the Y-axis direction of the flatness measuring device A, respectively Consider an XYZ coordinate system that matches the X-axis direction and the Y-axis direction. At this time, depending on the measurement result by the sensor D ₁ to D _4, each point _{P 1, P 2, P 3} , P 4 is the coordinates respectively _{(0,0, z 1), (} 100,0, z 2 ), (0,10
0, z ₃ ) and (100, 100, z ₄ ).

Here, points ₃ having points P ₁ , P ₂ and P ₃ as vertices
A plane F including a polygon and a straight line L passing through the point P ₄ and parallel to the Z axis.
Let P ₄ ′ (100, 100, z ₄ ′) be the intersection with
_{z 1 + z 4 '= z} 2 + z 3, i.e. _{z 4' = z 2 + z} 3 -z 1
The relationship holds. At this time, the plane F is
Normally, it does not become parallel to the ideal plane due to thermal expansion and straightness errors of mechanical systems such as the X-axis drive mechanism 20 and the Y-axis drive mechanism 30 that support 0.

That is, the plane F is inclined with respect to the ideal plane, but if the region R ₁ is a perfect plane, the point P ₄ and the point P ₄ ′ are theoretically identical. Therefore, the points P ₄ and P
₄ 'that diverge indicates that there is a flatness error to the region R _1, it is possible to calculate the flatness error to the following procedure.

That is, the distance between the point P ₄ and the point P ₄ ′ is dz
When _4, as shown in FIG. 6, the inspected surface WS region R ₁
Flatness M is seen can be approximated by dz _4/2 in. Therefore, flatness M in the region R ₁ of the inspected surface WS can be expressed by the following formula (1).

M = (z ₄ ′ −z ₄ ) / 2 = (z ₂ + z ₃ −z ₁ −z ₄ ) / 2 (1)

Thus, the region R₁Flatness detection
Is completed, the measuring mechanism 10 is moved to the region R₁And the area R adjacent to_Two
Move it up. That is, the first sensor D₁The point
P_ThreeAnd the second sensor D_Two
To the point P_FourTo move vertically upward. As a result, the third
Sensor D_ThreeIs the point P_Three100 mm point P in the Y-axis direction_Five
Moves vertically above the fourth sensor D_FourIs the point P_FourMore Y axis
100 mm point P in the direction ₆To move vertically upward. this
Region R in state₁In the same way as in_Three,
P_Four, P_Five, P₆Region R inside the square with the vertex_TwoSmell
Measure flatness.

In this manner, the measuring mechanism 10 is moved in the Y-axis direction or the X-axis direction by 100 mm to measure the flatness in each area R of a square having a side of 100 mm on the inspection surface WS. The inspection target surface W
The flatness per 100 mm square can be measured in the entire region of S. Then, the largest of the measured values is detected as the flatness of the work W. Further, by performing a process of continuously connecting the measured values, a profile of the entire work can be drawn.

As described above, according to the flatness measuring method of the present embodiment, the distance to each vertex of a square having a side of 100 mm on the inspection surface WS of the work W is measured at substantially the same time, so that the inside of the square can be measured. Since the flatness of the region R is measured and is measured over the entire inspection surface WS, the flatness measuring device A
Eliminates the effects of thermal expansion and straightness errors in the mechanical systems of
Can be precisely measured.

In the above embodiment, the measuring mechanism 10 has four distance sensors D. However, the present invention is not limited to this, and the number of sensors D can be five or more. .

Further, the measuring mechanism 10 is provided with only the sensors corresponding to the first and fourth distance sensors D ₁ and D ₄ , and the measuring mechanism 10 is connected to an axis passing through the midpoint between the two sensors.
By being configured to be rotatable by degrees, the flatness may be detected by measuring the distance up to four points twice and substantially simultaneously.

Further, for example, it is also possible to make the measuring area overlap by one measuring distance of 100 mm or less, and to perform the measurement with higher accuracy.

[0029]

The present invention will be described below more specifically.

Example 1 and Comparative Example 1 Table 1 shows the flatness measurement results (Example 1) measured by the flatness measuring method of the above-mentioned embodiment in comparison with reference values (Comparative Example 1).

Table 1 shows No. 1, No. 2, No. 3 of 3
Flatness per 100 mm square measured by a high-precision 3D measuring machine for each sample platen (Comparative Example 1)
And 1 measured by the flatness measuring method of the embodiment.
The flatness per 00 mm square (Example 1) is shown in comparison.

[0032]

[Table 1]

As is clear from Table 1, each sample N
o. 1 to No. The difference between the measurement results of Example 1 and Comparative Example 1 in Example 3 is about 0.001 mm to 0.002 mm, but this value is in a range that does not pose a problem in practical use.
Therefore, according to the flatness measuring method of the embodiment,
It can be seen that the measurement result of the flatness with almost the same accuracy as the measurement result by the very expensive high-precision three-dimensional measuring machine can be obtained.

Example 2 and Comparative Example 2 Table 2 shows the flatness per 100 mm square guaranteed by the maker of the reference material (Comparative Example 2) with respect to the reference material having a high-precision flatness. And the flatness per 100 mm square measured by the flatness measuring method (Example 2).

[0035]

[Table 2]

As is clear from Table 2, the difference between the two is 0.0001 mm, but this value is in a range that does not pose a problem in practical use. Therefore, according to the flatness measuring method of the embodiment, it can be seen that a very high-precision measurement result can be obtained with a relatively inexpensive device.

[0037]

As described above in detail, according to the present invention, at least four points on the surface to be measured are measured at substantially the same time by the distance sensor to measure the flatness of the work. Therefore, it is possible to eliminate the influence of the measurement error caused by the thermal expansion and the straightness error of the measuring jig. With this, the flatness of the work can be accurately measured even in a factory having a manufacturing line and in which temperature control is difficult, so that it is easy to perform the flatness inspection on all of the manufactured works. The effect that the measurement result of the flatness can be reflected in the manufacture of the work can also be achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a flatness measuring device to which a flatness measuring method according to an embodiment of the present invention is applied.

FIG. 2 is a front view of the device.

FIG. 3 is a block diagram showing a schematic configuration of a measurement mechanism of the apparatus.

FIG. 4 is an explanatory diagram illustrating a procedure of a flatness measurement method according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram for explaining the principle of the flatness measurement method.

FIG. 6 is an explanatory diagram for explaining the principle of the flatness measurement method.

FIG. 7 is an explanatory diagram for explaining an example of a conventional flatness measurement method.

[Explanation of symbols]

 Reference Signs List 10 measuring mechanism 20 X-axis driving mechanism 30 Y-axis driving mechanism 40 X / Y-axis driving driver 50 Controller A Flatness measuring device D Distance sensor W Work WS Inspected surface

Claims (5)

[Claims] 1. A flatness measuring method for measuring the flatness of a workpiece, comprising: measuring at least four points on a surface to be measured simultaneously or substantially simultaneously with a distance sensor, and processing the measured values appropriately. A flatness measuring method, wherein the flatness of the work is measured. 2. The method of claim 1, wherein the measurement of the flatness is a first point measured,
The method is performed based on a difference in distance between a point corresponding to a fourth point on a plane formed by the three points of the second point and the third point, and the fourth point. 2. The flatness measurement method according to 1. 3. A first point, a second point, a third point, and a fourth point are arranged so as to form a square, and a distance between a point corresponding to the fourth point and a fourth point. 3. The flatness measuring method according to claim 2, wherein 1/2 of the difference between the two is defined as the flatness of the surface to be measured. 4. A measuring mechanism having a predetermined arrangement of sensors for measuring a distance to a surface to be measured, a first driving mechanism for moving the measuring mechanism in one direction, and a second driving mechanism for moving the measuring mechanism in a direction orthogonal thereto. And a driver for driving the first drive mechanism and the second drive mechanism, and a controller for controlling the driver and calculating the measured value from the measurement mechanism to measure the flatness of the surface to be measured. A flatness measuring device, characterized in that: 5. The flatness measuring device according to claim 4, wherein the sensors are arranged so as to form a square.