JP2641597B2 - A method for detecting the shape of a plate using multiple slits - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention evaluates the surface condition of a treated plate material during the treatment of a plate-like body such as rolling of a steel plate by examining the unevenness of the surface of the treated plate material, ear waves, and the like. The present invention relates to a technology for detecting and evaluating a shape.

[Prior Art] Conventionally, there are two methods for optically detecting the shape of such a steel sheet, a method using a light source having directivity like a laser and a method using a scattering light source.

The method using a laser light source has the advantage of detecting the cross-sectional shape as it is, but for example, on a test plate such as a tin plate that has a remarkable reflection, the image where the laser beam hits the test plate is not reflected, Because light has width,
There is a drawback that it is difficult to detect bending, and it can be said that a method using a scattered light source is excellent in terms of shape detection in rolling a steel plate or the like.

As a detection method using this scattered light source, JP-A-57-17
There is a method disclosed in Japanese Patent Publication No. 2204. This is achieved by observing the distortion of the reflected image on the plate material surface by using a rod-shaped light source and a point light source depending on the characteristics of the plate material surface.
This is to evaluate the shape of the plate material.

Also, the method disclosed in JP-A-62-117505 is
The positional relationship between the rod-shaped light source and one slit is changed, and the shape of the steel plate is estimated from the interval between the two irradiation lines at that time.

In any case, the detection method using the scattered light source captures a reflected image of a single light source with a temporal shift, captures a shape as a surface, and estimates a cross-sectional shape.

However, in the method using the scattered light source, when the object to be detected is vibrating, the reflected image is blurred, and the image obtained under various different conditions is used to estimate the surface. In this case, there is a disadvantage that not only the combining process is troublesome but also the accuracy is low.

[Problems to be solved by the invention]

The present invention solves the drawbacks of the conventional shape detection method using a scattered light source and establishes a means for easily and accurately grasping the shape even when the detection target plate is vibrating.

[Means for solving the problem]

The present invention arranges a plurality of slits vertically cut across a plate and a high-speed imager, and captures a regular reflection image of the scattered light from the plurality of slits on the surface of the plate by the high-speed imager. Calculate the position of the reflection point from this imaging result,
The longitudinal inclination of the test plate at the reflection point is estimated from the calculation result, the same processing is performed on the reflection image of each slit, and the shape is detected by connecting the results.

[Action]

By using a plurality of slits in front of the scattered light source, the scattered light is linearly and uniformly irradiated on the steel sheet surface in the plate width direction, and the shape can be estimated by connecting the distortion of the reflected light.

That is, the reflection image is a linear image of the same number as the slits. Image processing is applied to this, and position information of the reflection point is obtained from the image data. Since the inclination of the reflection point is a function of the position information of the reflection point, the inclination at the reflection point is calculated from this function. The same process is performed for each reflection point, and the surface shape is detected by connecting the steel plates in the longitudinal direction. Image blur due to vibration can be prevented by using a high-speed imager such as a high-speed shutter camera.

〔Example〕

 FIG. 1 shows an embodiment of the present invention.

In the figure, 1 is a high-speed imager, 2 is a slit plate having a plurality of vertical slits 3 installed on the front of a scattered light source (not shown), and 4 is a steel plate to be detected. In the coordinate system shown in the figure, the y-axis direction and the longitudinal direction of the steel sheet coincide with each other, and the xy plane and the steel sheet plane coincide with each other, and the z-axis is an axis perpendicular to the steel sheet plane.

Under this setting condition, the light from the i-th slit 3 _i from the left among the plurality of slits is specularly reflected at the point 5 on the steel plate 4 and enters the high-speed imaging device 1.

With reference to the figure, a slit 3 _i, points on the steel plate 5, the respective coordinates of the high-speed imaging device _{1, (x s, y s} , z s), (x w, y
_p, z _p), and _{(x c, 0, z c} ).

FIG. 2 shows each slit 3 obtained by the method of FIG.
5 shows an image of a reflection image from the camera. Referring to the image drawing is scanned in the horizontal direction as a pixel number N _r from the top corresponding to the steel plate on the position x _W. From the i-th data N _r of position data from the left end of the thus obtained horizontal direction (width direction) is calculated y-coordinate y _p of the reflection point 5.

The normal vector of the steel sheet at point _{5 (a x, a y,} a z) is _{k 1 = {(x w -x} c) 2 + y p 2 + z p 2} -1/2 k 2 = {(x w -x s) 2 + (y p -y s) 2 + (z p -z _s ) It is expressed as ² ｝ ^−1/2 .

Here, x _c , z _c , x _s are constants given at the time of setting, and y _s , x _w
Is a constant determined when the reflection point is selected, and z of the steel sheet
Assuming that the displacement in the axial direction is small compared to z _c and z _s , z _p = 0. Furthermore, ignoring the tilt in the x-axis direction, a _x = 0
Than, Becomes Therefore, if y _p is calculated from the image data, the normal vector (a _h , a _y , a _z ) can be obtained.

The inclination θ of the steel sheet is Required by

Widthwise position x = y-coordinate y ₁ of the specular reflection point of the light from the slits in the x _w, y _2, ···, inclination theta ₁ and the corresponding y _{n, θ 2,} ···, is theta _n When determined, the cross section of the steel sheet at x = x _w is detected as Figure 3.

By executing by changing the x _w in the above processing, for example 20mm spacing, the shape of the steel sheet surface is detected.

〔The invention's effect〕

According to the present invention, the surface shape of the steel sheet is reproduced as it is from one screen of the imaging result obtained by the scattered light source. For this reason, it is possible to capture the feature of the shape, instead of expressing the shape with a representative value such as the degree of sharpness as in the related art. In addition, since the surface shape is estimated from the imaging result at the same time, the use of a high-speed shutter camera makes it possible to minimize deterioration in accuracy due to vibration. Therefore, it is possible to three-dimensionally detect a non-contact and vibration-resistant steel sheet surface shape.

[Brief description of the drawings]

FIG. 1 shows an outline of the steel sheet surface shape detection method of the present invention. FIG. 2 shows an example of an imaging result, and FIG. 3 is an explanatory diagram for reproducing a shape. 1: Imager, 2: Slit plate 3: Slit, 4: Steel plate 5: Reflection point on steel plate

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shinichiro Tahara 1-1, Hibata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture Nippon Steel Corporation Yawata Works (56) References JP-A-57-172204 (JP, A) JP-A-61-241612 (JP, A) JP-A-62-117505 (JP, U)

Claims (1)

(57) [Claims] 1. A high-speed imager and a plurality of slits cut in a vertical direction across a plate-like body, and a regular reflection image of scattered light from the plurality of slits on a surface of the plate-like body is taken by the high-speed imager. Then, the position of the reflection point is calculated from the imaging result,
Estimating the longitudinal inclination at the reflection point from the calculation result, performing the same processing on the reflection image of each slit, and estimating the shape by connecting the results, a plate-like body shape detection method using multiple slits .