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KR-20260064125-A - APPARATUS FOR DETECTING SURFACE DEFECTS OF STEEL SHEET

KR20260064125AKR 20260064125 AKR20260064125 AKR 20260064125AKR-20260064125-A

Abstract

The present invention provides a defect inspection device for a steel plate comprising: a first lighting unit disposed on the side of a first surface of a steel plate and irradiating a first lighting light onto the first surface; a second lighting unit disposed on the side of a second surface of a steel plate opposite to the first surface and irradiating a second lighting light onto the second surface; a camera unit disposed on the side of the first surface, receiving the first lighting light reflected from the first surface and receiving the second lighting light that has passed through a defective portion of the steel plate; and a detection unit that detects a defective portion present in the steel plate based on image information provided by the camera unit.

Inventors

  • 임여종
  • 김대현
  • 이성훈
  • 안성수

Assignees

  • 주식회사 포스코

Dates

Publication Date
20260507
Application Date
20241031

Claims (11)

  1. A first lighting unit disposed on the first surface side of a steel plate and irradiating a first lighting light onto the first surface; A second lighting unit disposed on the side of the second surface of the steel plate opposite to the first surface and irradiating a second lighting light onto the second surface; A camera unit disposed on the first surface side, receiving the first illumination light reflected from the first surface and receiving the second illumination light that has passed through the defective portion of the steel plate; and A defect inspection device for a steel plate comprising: a detection unit that detects a defect portion present in the steel plate based on image information provided by the above camera unit.
  2. In paragraph 1, The first lighting unit and the second lighting unit illuminate light in a flashing manner with a time difference of a certain period, A defect inspection device for steel plates in which the first illumination light and the second illumination light alternately enter the camera unit with a time difference.
  3. In paragraph 1, A defect inspection device for a steel plate further comprising: a light intensity control unit that controls the light intensity of the second lighting unit based on the gray value of the width-direction boundary portion of the steel plate detected by the camera unit.
  4. In paragraph 1, the second lighting unit is, A defect inspection device for steel plates in which multiple individually controllable lighting modules are arranged along the left-right direction.
  5. In paragraph 1, A steel plate defect inspection device further comprising: a control unit for adjusting the position and/or angle of at least one of the camera unit, the first lighting unit, and the second lighting unit.
  6. In paragraph 5, the above-mentioned control unit is, A defect inspection device for steel plates comprising a camera control unit for adjusting the position and/or angle of the above camera unit.
  7. In paragraph 5, the above-mentioned control unit is, A defect inspection device for a steel plate comprising: a first lighting control unit for adjusting the position and/or angle of the first lighting unit.
  8. In paragraph 5, the above-mentioned control unit is, A defect inspection device for a steel plate comprising: a second lighting control unit for adjusting the position and/or angle of the second lighting unit.
  9. In paragraph 5, The first lighting unit and the second lighting unit irradiate linear lighting light along the width direction of the steel plate, and The above-mentioned control unit is, The first lighting unit and the second lighting unit are adjusted so that the first lighting light and the second lighting light are positioned at positions spaced apart in the front-rear direction on a plane, and The above camera unit is, A defect inspection device for a steel plate comprising an area-sensing camera that collects image information for a shooting area having a constant shooting width in the left-right direction and a constant shooting length in the front-back direction, and receiving the first illumination light and the second illumination light.
  10. In paragraph 5, The first lighting unit and the second lighting unit irradiate linear lighting light along the width direction of the steel plate, and The above-mentioned control unit is, The first lighting unit and the second lighting unit are adjusted so that the first lighting light and the second lighting light intersect at an acute angle on a plane, and The above camera unit is, A defect inspection device for a steel plate comprising an area-sensing camera that collects image information for a shooting area having a constant shooting width in the left-right direction and a constant shooting length in the front-back direction, and receiving the first illumination light and the second illumination light.
  11. In paragraph 1, A third lighting unit disposed on the second side of the steel plate and irradiating a third lighting light onto the second side; A fourth lighting unit disposed on the side of the first surface of the steel plate opposite to the second surface and irradiating a fourth lighting light onto the first surface; and A defect inspection device for a steel plate further comprising: a second camera unit disposed on the second surface side, receiving the third illumination light reflected from the second surface, and receiving the fourth illumination light that has passed through the defect portion of the steel plate.

Description

Apparatus for detecting surface defects of steel sheet The present invention relates to a defect inspection device for steel plates. It should be noted that the content described in this section merely provides background information regarding the present invention and does not constitute prior art. In conventional technology, a defect inspection device for steel plates installs lighting and a camera at a certain angle perpendicular to the surface of the steel plate to take a picture and distinguishes the steel plate from the surrounding area (parts that are not steel plates) based on the gray value of the steel plate. The gray value for pure white is 255, and the gray value for pure black or pure white can be 0. The most critical defect in steel sheets is hole defects caused by holes occurring in any part of the sheet. Hole defects vary greatly in shape and size; microscopic defects are very difficult to detect even with the naked eye of an expert, and this presents a problem as they are even more difficult to detect during high-speed roll-to-roll processes. FIG. 1 is a perspective view of a defect inspection device for a steel plate of a comparative example compared with the present invention. Figure 2a is a drawing illustrating a state in which meandering occurs in a steel plate being transported. Figure 2b is a drawing illustrating a state in which an upward bend occurs in a steel plate being transported. Figure 2c is a drawing illustrating a state in which a downward bend occurs in a steel plate being transported. FIG. 2d is a drawing illustrating the state in which a wave occurs in a steel plate being transported. FIG. 3 is a perspective view of a defect inspection device for a steel plate according to one embodiment of the present invention. Figure 4a is a cross-sectional view in the direction I-I' of Figure 3. Figure 4b is a cross-sectional view in the direction II-II' of Figure 3. FIG. 5a is a cross-sectional view illustrating the scattering phenomenon of the second lighting unit of the defect inspection device of the steel plate of FIG. 3. FIG. 5b is a plan view illustrating a state in which a light fading phenomenon occurs at the boundary portion in the width direction of the steel plate due to the scattering phenomenon of the second lighting unit of the defect inspection device of FIG. 3. FIG. 6 is a perspective view illustrating a second lighting unit and a light intensity control unit included in a defect inspection device for a steel plate according to another embodiment of the present invention. FIG. 7 is a cross-sectional view illustrating a control unit included in a defect inspection device for a steel plate according to another embodiment of the present invention. FIG. 8 is a conceptual diagram illustrating the position and/or angle adjustment of a camera unit included in a defect inspection device for a steel plate according to another embodiment of the present invention. FIG. 9 is a conceptual diagram illustrating the position and/or angle adjustment of the first and second lighting units included in a defect inspection device for a steel plate according to another embodiment of the present invention. FIG. 10a is a plan view in which the first lighting unit or the second lighting unit is positioned and/or angled so that the first lighting light and the second lighting light are spaced apart in the front-rear direction. FIG. 10b is a cross-sectional view in which the first lighting unit or the second lighting unit is positioned and/or angle is adjusted so that the first lighting light and the second lighting light are spaced apart in the front-rear direction. FIG. 11 is a plan view in which the first lighting light and the second lighting light are arranged to be staggered by adjusting the position and/or angle of the second lighting unit. FIG. 12a is a cross-sectional view of a defect inspection device for a steel plate according to another embodiment of the present invention, illustrated in the direction I-I' of FIG. 3. FIG. 12b is a cross-sectional view of a defect inspection device for a steel plate according to another embodiment of the present invention, illustrated in the direction of II-II' of FIG. 3. Preferred embodiments of the present invention will be described below with reference to the attached drawings. However, embodiments of the present invention may be modified in various different forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. In the drawings, the shapes and sizes of elements may be exaggerated for clearer explanation. In describing the embodiments of the present invention, if it is determined that a detailed description of known technology related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description will be omitted. Furthe