JPH04157308A - Detecting method and apparatus of warp in widthwise direction of steel band - Google Patents

Abstract

PURPOSE:To measure the warp of a steel band irrespective of the positional displacement by casting a linearly processed light beam to the steel band, picking up information of the reflecting light as the image data and processing the image data. CONSTITUTION:A light beam LB which is linearly processed in tire widthwise direction of a steel band 1 is cast from diagonally above in the longitudinal direction of the steel band 1 from a linearly processed light beam generating device 2. The light beam LB is wide in the widthwise direction of the steel band 1, but not expanded in the longitudinal direction of the steel band 1. Therefore, if the steel band 1 has a warp on the surface thereof, the light beam LB shows a semi-arch line spectrum GL. The reflecting light of the line spectrum GL is taken into an image input device 3 as the image data from the approximately exactly opposite direction. Thereafter, an image processing device 4 performs processing of the image of the reflecting light of the line spectrum GL input from the device 3 up to measurement of the physical amount corresponding to the amount of the warp. The reflecting light of the line spectrum GL by the light, beam LB is projected to a screen 5 as a projecting image RF.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method and apparatus for detecting warp in the width direction of a steel strip.

<Conventional technology> Flatness of steel strip is one of the important quality control items during product shipping, especially in recent years for labor saving.

Due to the spread of automation, customers are complaining of various problems such as the fact that steel strips with poor flatness cannot be processed by automatic machines, and the importance of steel strips is increasing.

- There is "warp" as a factor that inhibits flatness of m.
Depending on the form in which it occurs, warping in the longitudinal direction of the steel strip is usually called "L-warping," and warping in the width direction of the steel strip is called "zero warping." Among these, "L-warping" There is no particular problem with "C warpage" as it can be corrected with a normal leveler, but "C warp" cannot be completely corrected with a normal leveler in most cases, so "zero warpage" should not occur in the steel strip manufacturing process. This is a necessary condition.

In order to prevent such "0 warpage" (hereinafter simply referred to as warpage) from occurring, it is first necessary to measure the warpage by some method, feed back that information, and take prompt countermeasures. 68] Publication No. 04, as shown in FIG. 5, parallel light is irradiated from the irradiation light source 2 at a predetermined angle θ obliquely in the longitudinal direction of the steel strip 1, and the light beam is applied to the steel strip 1. Move horizontally in the width direction of
The locus of the bright spot formed at the intersection of this light beam and the steel strip 1 is detected by an optical sensor 3 such as a line sensor installed almost vertically above the steel strip 1. A method is disclosed for detecting directional displacement and measuring the amount of warpage.

<Invention tries to solve! 11111> However, in the above-mentioned warp detection method of JP-A-60-68104, if there is vertical fluctuation in the steel strip l, that fluctuation is also recognized as the amount of warp, so it is difficult to accurately detect the amount of warp. The drawback is that it cannot be done.

Furthermore, when a line sensor or the like is used as the optical sensor 3, the range that can be imaged, the so-called detectable range, is narrow.
There are cases where the light source 2 moves out of the detectable range due to axis fluctuations, the steel strip 1 tilts, etc., and measurement becomes impossible.

In addition, in order to achieve sufficient measurement accuracy, it is necessary to shine light onto the target object, such as a steel strip, at a low angle, but this is often impossible due to line layout problems.

Furthermore, if the optical sensor 3 is installed so as to be viewed from above the steel 11 in an almost vertical direction, a high-gloss steel strip will have a large specular reflection component, making it impossible to obtain a sufficient amount of light for the optical sensor 3. Measurement may become impossible.

The present invention is as described above! It is an object of the present invention to provide a method and apparatus for detecting warp in the width direction of a steel strip, which solves the problem and enables highly accurate measurement even if there is a change in the position of the steel strip or a light source.

Means for Solving the Problems> A first aspect of the present invention includes a step of projecting a linear light beam in the width direction of the steel strip from diagonally above the steel strip in the longitudinal direction;
A process of capturing the reflected light of this linearized light beam by the steel strip as image data from the position of almost regular reflection, and processing of inputting this image data and measuring the physical quantity corresponding to the amount of warpage from the image. A method for detecting warpage in the width direction of a steel strip, comprising: an image processing step.

Note that when capturing the reflected light of the linearized light beam as image data, a step of detecting the projected image through a screen may be added.

Further, a second aspect of the present invention includes a laser beam generator and a cylindrical lens that are attached above the steel strip and project a linear light beam in the width direction of the steel strip from obliquely in the longitudinal direction of the steel strip. a linearized light beam generating device comprising a lens system including a lens system; and a linearized light beam generator configured to generate a linearized light beam at a substantially regular reflection position of the reflected light of the linearized light beam on the steel strip; Consisting of an image input device consisting of a CCD camera and a lens system that detects light as image data, and an image processing device that measures a physical quantity corresponding to the amount of warpage using the image data input from the image input device. This is an apparatus for detecting warpage in the width direction of a steel strip.

Note that a screen whose angle with respect to the optical axis is variable is provided in front of the image input device, and a projected image of the reflected light of the linearized light beam can be detected through the screen.

<Operation> According to the present invention, a linearized light beam emitted from a light source in the radial direction of the steel strip is reflected from the surface of the steel strip, and the reflected light image is converted into image data with a two-dimensional spread. Since the image can be captured as an image, a physical quantity corresponding to the amount of warpage can be measured from the image. At this time, the position of the bright line formed at the intersection of the linearized light and the steel strip may shift due to vertical fluctuations of the steel strip, but in that case, the captured image data will be unrelated to the imaging position. By measuring a physical quantity corresponding to the amount of warpage using such an image processing method, it is possible to perform warpage measurement that removes the influence of positional deviation.

Note that if a screen whose angle with respect to the optical axis is variable is provided in front of the image input device and the projected image of the reflected light of the linearized light beam is detected through the screen, the camera used for imaging can be Since it is possible to take pictures without causing burn-in, and the degree of distortion of the projected image can be increased, it is also possible to improve the accuracy of blade 1 measurement.

<Examples> Examples of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, 2 is attached to the upper part of the steel strip 1, which is an object, and projects linear light LB in the width direction of the steel strip 1 from diagonally above in the longitudinal direction of the steel strip 1. The optical beam generating device is composed of a laser beam generating device 2a and a lens system 2b including a cylindrical lens that converts the laser beam into a linearized optical beam LB. This linearized light beam LB has a property that it spreads in the width direction of the steel strip 1, but does not spread in the longitudinal direction. Half-arched ￥1. We will draw a line GL.

The range where this bright line GL is drawn on steel strip 1 is as follows:
It is desirable that the tension be about 200 degrees from the end of the line.The reason for this is that tension is normally applied to the steel strip 1 running along the line in the direction of arrow F, so even if there is a warp, it will not bend. This is because the value is smaller than the true value due to tension, and occurs approximately 200 m from the end of the steel strip 1, and the central portion is flat with no warpage.

Reference numeral 3 denotes an image input device which captures the reflected light of the bright line GL by the linearized light beam LB from the surface of the steel strip 1 as image data from a position of almost specular reflection, and includes a CCD camera 3a and its lens system 3b. configured. By making the imaging range of the CCD camera 3a wide enough to be unaffected by positional deviations of the steel strip 1 and the linearized light beam generator 2, it is possible to sufficiently follow vertical fluctuations of the steel strip 1. be able to.

Reference numeral 4 denotes an image processing device that performs processing from the image of the reflected light of the bright line GL inputted from the image input device 3 to measuring the physical quantity ΔL corresponding to the amount of warpage as shown in FIG.

5 is a screen such as a diffuser plate that projects the reflected light of the bright line GL by the linearized light beam LB as a projection image RF.

The effects of this screen 5 include the following three points. First, if the surface roughness of the steel strip 1 is small and the specular component of the reflected light is large, or if the light intensity of the light source is large, CC
Since there is a risk of image sticking on the D camera 3a, a screen 5 is provided in front of the image input device 3, that is, between the steel strip 1 and the CCD camera 3a. 3a, it is possible to reduce the amount of reflected light and avoid burn-in on the CCD camera 3a.

Furthermore, as shown in FIG. 2, by changing the angle of the screen 5 by α from the position perpendicular to the optical axis,
Projected image R corresponding to the warp projected onto the screen 5'
Since the degree of distortion of F can be increased, measurement accuracy can be improved by sending the displacement information to the image processing device 4.

Furthermore, since the screen 5 can reduce unnecessary noise light included in the reflected light,
This is effective in improving the S/N ratio in the image processing device 4.

Next, the image processing procedure in the image processing device 4 will be explained. If the steel strip 1 has a warp, the projected image RF of the reflected light projected on the screen 5 will show that the warp corresponds to the warp, as shown in FIG. By quantitatively measuring the magnitude of the distortion ΔL when the light is distorted, the magnitude of the warpage can be identified. For example, this identification method is as follows:
Removes noise and binarizes images input as multivalued images.

A possible method is to perform processing such as line thinning and then calculate the degree of distortion to determine the amount of warpage.

At this time, when vertical fluctuation occurs in the steel strip 1, the position of the imaged bright line GL moves, so the projected image RF of the reflected light moves to the position of RF', as shown in FIG. However, instead of applying an image processing method that is unrelated to this positional shift, that is, calculating ΔL using absolute coordinates with one point on the image as the origin, for example, as shown in Figure 4. Using relative coordinates such that the origin is the point 0.0' shown, Δ1. It measures. By applying such an image processing method, it is possible to accurately measure the amount of warpage.

<Effects of the Invention> As explained above, according to the present invention, the steel strip is irradiated with a linearized light beam, the reflected light information is imaged as image data, and an image processing method is used. It is possible to measure warpage unrelated to positional deviation. On the other hand, since a screen is provided in front of the image input device and its angle is adjusted, measurement accuracy can be improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the function of the screen, FIGS. 3 and 4 are explanatory diagrams of image processing, and FIG. 5 is a diagram of the configuration of a conventional example. It is an explanatory diagram. 1... Steel strip, 2... Linearized light beam generator. 2a... Laser light generator, 2b... Lens system. 3... Image input device, 3a... CCD camera. 3b... Lens system, 4... Image processing device,
5...Screen. Patent applicant: Kawasaki Steel Corporation Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] 1. A step of projecting a linearized light beam in the width direction of the steel strip from obliquely above the longitudinal direction of the steel strip, and directing the reflected light of the linearized light beam by the steel strip approximately in the correct direction. A process of capturing image data from the position of reflection, and an image processing process of inputting this image data and measuring a physical quantity corresponding to the amount of warpage. Warpage detection method. 2. Warpage in the width direction of the steel strip according to claim 1, further comprising a step of detecting a projected image of the reflected light of the linearized light beam through a screen when capturing the reflected light as image data. Detection method. 3. Linearization consisting of a laser beam generator installed above the steel strip and projecting a linearized light beam in the width direction of the steel strip from obliquely in the longitudinal direction of the steel strip, and a lens system including a cylindrical lens. a light beam generator; and a CCD camera installed at a substantially regular reflection position of the reflected light of the linearized light beam on the steel strip to detect the reflected light of the linearized light beam on the steel strip as image data. and a lens system; and an image processing device that measures a physical quantity corresponding to the amount of warpage using the image data input from the image input device. Warpage detection device. 4. A screen according to claim 3, wherein a screen whose angle with respect to the optical axis is variable is provided in front of the image input device, and a projected image of the reflected light of the linearized light beam is detected through the screen. A device for detecting warpage in the width direction of steel strips.