Method and apparatus for detecting cracks in the slab shoulder, method for grinding the slab shoulder, and method for manufacturing slab products.

Abstract

The present invention provides a slab shoulder crack detection method capable of detecting cracks occurring in the shoulder portion of a slab, and a slab shoulder grinding method capable of properly removing cracks in the shoulder portion. [Solution] The shoulder portion where two adjacent surfaces of a rectangular slab S intersect is ground to remove the crack W present in the shoulder portion. In this process, light intensity data is acquired by irradiating the shoulder portion with linear light at predetermined intervals in the longitudinal direction of the slab S. Shading-corrected light intensity data is obtained by dividing the light intensity data by its moving average, and a crack detection threshold is set for the shading-corrected light intensity data. If the shading-corrected light intensity data exceeds the crack detection threshold, it is determined that a crack W exists. Once the elongation dimension of the crack W is calculated, the shoulder portion is ground until the grinding dimension is equal to or greater than the elongation dimension.

Claims

1. A method for detecting cracks present on two adjacent surfaces of a rectangular prism-shaped slab at the shoulder portion where the two surfaces intersect, A slab shoulder crack detection method characterized by: irradiating the shoulder portion with linear light extending perpendicular to the longitudinal direction of the slab at predetermined intervals in the longitudinal direction of the slab, obtaining light intensity data and shape data detecting the shape of the shoulder portion; determining the intersection angle of the two surfaces from the shape data; obtaining shading-corrected light intensity data based on the moving average of the light intensity data in the longitudinal direction of the slab, setting a crack detection threshold based on the shading-corrected light intensity data; identifying a region in the longitudinal direction of the slab where the shading-corrected light intensity data exists continuously in the perpendicular direction, including the position corresponding to the angle, and where the shading-corrected light intensity data exceeds the crack detection threshold; and calculating the extension dimension of the crack in the perpendicular direction on the two surfaces from the distance from the angle in the range where the shading-corrected light intensity data exceeds the crack detection threshold in the region.

2. The slab shoulder crack detection method according to claim 1, characterized in that the crack detection threshold is set by adding or subtracting a value obtained by multiplying the standard deviation of the shading-corrected light intensity data by a predetermined value to the average value of the shading-corrected light intensity data.

3. The slab shoulder crack detection method according to claim 1, characterized in that the shading correction is performed by dividing the light intensity data by the moving average.

4. A device for detecting cracks present on two adjacent surfaces of a rectangular prism-shaped slab at the shoulder portion where the two surfaces intersect, The system comprises: a linear light irradiation unit that irradiates the shoulder portion with linear light extending in a direction perpendicular to the longitudinal direction of the slab; a light intensity detection unit that detects the reflected light obtained by irradiating the shoulder portion with the linear light; and a shape detection unit that detects the shape of the shoulder portion. A slab shoulder crack detection device characterized by detecting cracks present on the two surfaces of the shoulder portion based on the light intensity data of the reflected light detected by the light intensity detection unit and the shape data of the shoulder portion detected by the shape detection unit, using the slab shoulder crack detection method described in any one of claims 1 to 3.

5. A slab shoulder grinding method characterized in that, once the elongation dimension of the crack in the orthogonal direction on the two surfaces is calculated using the slab shoulder crack detection method according to any one of claims 1 to 3, the shoulder portion is ground on both surfaces and the shape of the shoulder portion after grinding is measured, and the shoulder portion is ground on both surfaces until the grinding dimension from the corner on the two surfaces is equal to or greater than the elongation dimension of the crack in the orthogonal direction.

6. A method for manufacturing a slab product, characterized by grinding the shoulder portion using the slab shoulder grinding method described in claim 4 to obtain a slab product.

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