JPH0450606A - Flatness gage - Google Patents

Abstract

PURPOSE:To measure flatness by applying laser beam to an object to be measured, detecting its reflection light by a plurality of two-dimensional detectors and calculating the detection signals. CONSTITUTION:Reflection light signals detected by two-dimensional CCD cameras 3A, 3B are supplied to a CPU 5 via an E/O device 4 sequentially according to scanning operation of the cameras, and calculation is performed. With respect to a calculated value hx, a coordinate of a measurement point is determined based on the scanning operation and a traveling speed signal of a plate material 1 from a counter 11, and the detection value hx is stored in a memory section in the CPU while it is associated with coordinate. The stored detection value is recorded on a recorder 8 and also is supplied to a CRT display 9 if necessary so that flatness is visually displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a flatness meter for measuring the flatness of various types of plate materials such as hot and cold steel plates.

[Prior Art] As a conventional example of measuring the flatness of a plane of a plate using optical means, there is the following method.

(1) A method that uses moiré photography technology to observe uniform lines of the measurement object as moiré fringes (Japanese Unexamined Patent Publication No. 63-2
(See Publication No. 9208).

(2) H modulated at two frequencies simultaneously using a laser rangefinder
The e-N e laser beam is irradiated onto the target object, the diffusely reflected light is focused, converted into an electrical signal by a high-speed photomultiplexer via an automatic focusing mechanism, and the received signal is frequency-converted and averaged, and the phase difference is A method of measuring the distance to the object by measuring the flatness of the object (Japanese Patent Laid-Open No. 63-2
(See Publication No. 324).

(3) A method in which a plurality of laser rangefinder sensors are used to measure the distance to the object for each predetermined length of the object, and measure flatness based on the distance (see Japanese Patent Laid-Open No. 10563/1983).

(4) A method in which the plate wave height is measured using multiple laser displacement meters arranged in the width direction of the object, and the arc length of the plate wave in a certain traveling section is simultaneously measured in the width direction 2
(See Publication No. 770).

(5) A method in which two laser displacement meters are used, each detects the laser reflected light with a parallax, and the flatness is measured based on this (see Japanese Patent Laid-Open No. 111708/1983).

(6) Method of measuring flatness by irradiating laser beams with two different wavelengths and detecting the reflected light (Japanese Patent Laid-Open No. 58-11
(See Publication No. 5314).

[Problem to be Solved by the Invention 1] Conventional techniques for measuring flatness include the methods described above, but each has problems as described below.

The moiré photography method (1) above is performed using many cutting lights, but the resolution is poor due to the ITV series, it is difficult to detect the flatness in the longitudinal direction due to calculation processing, and it is difficult to detect when the pass line fluctuation is large. Because the pass line fluctuations and flatness defects are added together, the displacement in the thickness direction of the plate cannot be accurately measured.

In the method (2) above, modulation of laser light is used to
; Although it has a characteristic point, there are large fluctuations due to flatness defects during modulation, and a large part of the field of view cannot be measured. Also,
Since the structure of the measuring device is complex, adjustment error factors are included in the measured values, resulting in large errors. Furthermore, H as modulated light
Since an e-N e laser is used, the lifespan of the laser light source is 10'H.

degree and short.

In the method (3) above, since a laser distance meter is used, error factors due to path line fluctuations are included in the measured value, resulting in a poor S/N ratio.

Furthermore, since the distance detection sensitivity of the distance meter itself varies depending on the length, it is unclear how accurate the measurement actually is.

In method (4) above, since a laser displacement meter is used, errors due to path line fluctuation factors become large.
The flatness accuracy becomes as large as about ±4, and the relative detection accuracy becomes particularly low for thin objects. In addition, a twin beam method is adopted in consideration of the plate vibration of the object, but accuracy control is practically difficult because the displacement difference is small. Furthermore, since the beam method does not allow the entire surface to be seen, it is difficult to detect the distribution of flatness in the width direction. Furthermore, since it is not possible to maintain a large distance between the sensor and the object to be measured, the locations where the sensor can be installed are limited.

In the method (5) above, since two laser beams are focused on one detector, a supplementary limit occurs in the detector due to the flatness angle. Furthermore, since a displacement meter is used, the influence of path line fluctuations is included as an error.

In the method (6) above, it is necessary to perform numerical correction using laser beams of two different wavelengths, and at the same time, a means for identifying wavelengths is required.

As mentioned above, the conventional method has problems with pass line fluctuations,
There are problems such as difficulty in detecting the widthwise distribution of flatness, large measurement errors due to the need to use a sensor with a large S/N ratio, and the necessity of wavelength identification and numerical correction.

[Means for Solving the Problems] Uami: In order to solve the problems of the conventional technology, the present invention irradiates the object to be measured with laser light and uses a plurality of two-dimensional detectors to detect the reflected light in a field of view. The feature is that the flatness can be measured by providing and detecting the flatness and calculating the detected signal.

[Example] Fig. 1 shows an example of the present invention, in which 1 is a plate material such as a steel plate that is the object to be measured, 2 is a laser light source that irradiates the width direction of the plate material, 3A, 311 is a two-dimensional C that detects the light from the laser light source 2 reflected by the plate 1.
CD camera, 4 is E10 device, 5 is CPU, 6 is process computer, 7 is desk, 8 is recorder, 9 is CR
T-display 10 is a PLG that detects the rotation of a roll for transporting the plate 1 and outputs a pulse, and 11 is a counter that counts the pulses from the PLG 10 to detect the traveling speed of the plate 1.

The principle of the present invention will be explained with reference to FIGS. 2 to 4.

As shown in FIG. 2, the laser light source 2 is configured to emit laser light parallel to the entire length of the plate 1 in the width direction and at a predetermined radius W in the longitudinal direction (running direction). The center line is arranged so as to intersect measurement point 0 of the plate material 1. The cameras 3A and 3B are each arranged at a predetermined height H with respect to the surface of the plate material 1, and the extreme end (external part in the longitudinal direction) of the parallel laser beam is placed on the plate material 1 in an ideal flat state (virtual plane). It is arranged so that the reflected light from the points P1 and P2 intersecting with can be detected at a predetermined angle θ.

And a line connecting camera 3A and point P, and camera 3B
The line connecting point P2 is point R on the center line of the parallel laser beam.
The distance between point 0 and point R is ho. Further, the distances in the longitudinal direction from the point R to the cameras 3A and 3B are respectively determined.

Expressing the above relationship mathematically, tan&=2ho/W = (H+ho)/L (1) If the part of the plate material 1 irradiated with the parallel laser beam is flat and has no unevenness, then the camera 3A, 3. Both detect that point P1% and point P2 are the extreme points irradiated with the parallel laser beam, so
As shown in the lower part of FIG. 2, it is detected that the deviations al, a2, b+, and bz from the point Pi, point P2 as seen from each camera on the line AB on the plate 1 are all 0, Therefore, the deviation at detection point 0 is ao=(a,+ax)/2=O bo-(b++b2)/2=.

is obtained, and it is detected that there is no unevenness at point 0 when viewed from the virtual plane.

On the other hand, if a convex portion exists near the point O of the plate l as shown in FIG.
Since it intersects with plate l at , camera 3 detects that the end of the laser beam is in the direction of point PIA%, point P2A, and camera 3B detects that the end of the laser beam is in the direction of point P4, point P. Detect that.

Therefore, as shown in the lower part of FIG. 3, the deviations from point P1 to abl and from point P2 to a2 and b2 are detected.

Then, by averaging these deviations, the displacement a at point 0 is
0 and b are obtained by the following calculation: ao=(a+”az)/2 1)0=(bi+bi)/2.

How to determine the displacement in the height direction at point O based on ao and bo determined in this way will be explained with reference to FIG.

FIG. 4 is an enlarged view of a portion centered on point R in FIG. 3, and the displacements a0 and bo were determined as described above.

As is clear from the figure, the angle θ' is θ' - π/2-θ, so hA=ao/lanθ' = a,/cotθ (2) h B =
b o/t a nθ'=b0/cotθ
(3), and if the displacement in the height direction at point O is the distance hx from point R to point R', then h x =
hB+ (be (hA ha)l / (ao+b
o)= (a+1bB+bohA)/(ao+bo)
becomes. Then, if we transform the above equation based on equations (2) and (3), we get hX=2aobo/ (co tθ (ao+bo)1
Based on equation (1), hX=2aobo/(ao+bo)XH/(2L w
) is obtained, and using equation (4) or (5), the displacement h
x is required.

As described above, the displacement hx in the height direction at point 0 is obtained, but the cameras 3A and 3B scan a predetermined width (more than the width W of the parallel laser beam) in the length direction of the plate material 1, and The displacement of the point O, which is the center point, is detected based on the detected reflected light, and by repeating this in the sheet width direction, the displacement of each point in the sheet width direction including point O is detected. Further, since the plate material 1 is traveling at a predetermined speed, by repeating the above steps, the longitudinal direction of the plate material 1 is also scanned, and the flatness can be detected over substantially the entire surface of the plate material 1.

Returning to FIG. 2, to explain the outline of the operation of the present invention, the reflected light signals detected by the two-dimensional CCD cameras 3A, 3A are sequentially supplied to the CPU 5 via the E10 device 4 in accordance with the scanning operation of the cameras. , operations such as those described with respect to FIGS. 2-4 above are performed. The obtained value hx is
Based on the scanning operation and the traveling speed signal of the plate material 1 from the counter 11, the coordinates of the measurement point are determined, and the detected value hx is stored in the memory section in the CPU in association with the coordinates. The stored detection values are recorded in the recorder 8 and displayed on the CRT display 9 as necessary.
The flatness is visually displayed. Note that the process computer 6 has a built-in program and is used to control the operation of the entire apparatus.

[Effects] Since the present invention is configured as described above, the following effects can be achieved.

a. By increasing the installation height H of the camera to a certain extent, it is possible to make the influence of path line fluctuations negligible.

b. By appropriately adjusting the distance in the longitudinal direction from the above H and the measuring point O to the camera, the deviation a ol b
The value of o can be changed with sufficient precision, and variations in the value can be detected more closely than the actual flatness, so even minute displacements can be detected.

By adjusting C and beam width W, accuracy can be further improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing one embodiment of the present invention, and FIGS. 2 to 4 are explanatory diagrams for explaining the present invention in detail. 1... Plate material 2... Laser light sources 3A, 3B... 2-dimensional CCD camera No. 2 Fig. evening % direction No. 117

Claims (1)

[Claims] 1. A light source that is disposed above a plate running in the longitudinal direction and irradiates a parallel beam having a predetermined width in the longitudinal direction of the plate across the entire width of the plate; , two two-dimensional cameras that detect the reflected light reflected by the plate material, the cameras are arranged symmetrically with respect to the light source, and scan and detect the reflected light in the same direction and at the same pitch in the width direction. Dimensional camera. Based on the detection signals from each camera, determine the direction in which the longitudinal end of the parallel beam intersects with the plate material, and then calculate the displacement in the height direction at the point where the parallel beam center line intersects with the plate material. A flatness meter for measuring the flatness of a plate material, characterized in that it is equipped with: