KR19980052448A - Cold rolled steel surface defect detection device - Google Patents

Abstract

The present invention relates to the provision of an apparatus for detecting defects on the surface of a steel plate continuously running at a constant speed in one direction.

The apparatus of the present invention is adapted to irradiate a monochromatic light of a predetermined width onto the box (3) for advancing the steel sheet (1) to the inside of the outside of the inflow of external light, and the steel sheet (1) for proceeding inside the box (3) A monochromatic light source 4 and an optical line forming window 8 installed inside the box 3, a line scan camera 5 installed inside the box 3 so as to photograph the steel sheet 1 to which the monochromatic light is irradiated at high speed; And an image processing system 7 for processing image information from the camera 5.

The apparatus of the present invention irradiates monochromatic light onto the moving steel sheet 1 in a highly controlled state without interference of external light, and photographs the portion of the steel sheet 1 to which the monochromatic light is irradiated with a high-speed line scan camera 5 to detect the monochromatic light. By analyzing the image information, it is possible to continuously detect fine defects on the moving steel sheet 1 more precisely than before.

Description

Cold rolled steel surface defect detection device

The present invention relates to a cold-rolled steel sheet surface defect detection device configured to more accurately detect the fine grooves, scratches, and residual contaminants formed on the surface of the steel sheet during the continuous stainless cold rolled steel sheet manufacturing.

On the surface of the cold rolled steel sheet continuously processed, defects due to roller abnormalities, fine particle inclusions, and foreign matter adhesion such as surface coating film by degreasing liquid occur in the production of cold rolled steel sheet. There is a need for a measurement and analysis device capable of detecting surface defects, and the present invention provides a device including a precise optical system and a scan camera, which can accurately detect micro defects of 0.1 mm x 0.1 mm level. to provide.

In general, defect detection of a steel sheet continuously proceeding is more difficult than defect detection on a stopped steel surface, and since most of the existing defect analysis systems are designed to be used to obtain defect information on a steel sheet in a stopped state. Applying to moving objects has many problems. In particular, when the minimum detection size of the defect is reduced to 1 mm x 1 mm or less, it is impossible to obtain complete defect information due to the performance limitation of the overall defect detection equipment.

Conventional defect detection methods on the surface of the steel sheet has been made depending on the total inspection of the operator, on-line inspection using a laser, defect detection using an optical system has been attempted. However, all of these methods have a disadvantage that it is difficult to obtain comprehensive and systematic information because defect inspection is conducted from the individual's point of view of the operator. There is a disadvantage that is sensitive to the external environment, such as particle scattering effect of. On the other hand, the defect inspection apparatus using the optical system has difficulty in detecting the minimum size of the defect desired by the user due to the lack of an appropriate optical system for the measurement steel sheet and the performance limit of the optical camera.

The present invention uses a scan camera having a detection unit element of 4096 using a monochromatic light having a wavelength of 0.6 to 1.2 占 퐉 and a defect detection system for obtaining defect information thereof with a minimum defect size of 0.1 mm x 0.1 mm. By providing an optical defect detection system for detecting defects on the surface of the continuous steel sheet to precisely detect the minute defects formed on the surface of the steel sheet.

That is, the present invention includes an optical system using monochromatic light, a measurement system consisting of a line scan camera having a measurement speed of 60 MHz, and a data processing system in view of the problem of detecting the minimum defect size of the conventional steel plate surface defect detection means. It is an object of the present invention to provide a device capable of accurate and reproducible steel sheet surface defect detection.

1 is a general configuration diagram of an apparatus according to the present invention.

2 is a configuration diagram of a line scan camera and an image processing apparatus of the present invention.

* Description of the symbols for the main parts of the drawings *

1: steel sheet 2: guide roll

3: light blocking box 4: monochromatic light source

5: line scan camera 6: encoder

7: image processing system 8: optical line forming window

9: Image processing board 10: Monochromatic light

11: light line

In order to achieve the above object, the defect detecting apparatus of the present invention first introduces a moving steel sheet to which a defect is detected, into a box in which external light is blocked so that defects on the steel sheet in the optical system portion can be sufficiently observed in the light receiving portion of the camera. Proceeds through the anti-vibration guide roll, the monochromatic light from the light source is irradiated to the steel sheet in the box. When light is incident on the surface of the steel sheet according to light reflection on the surface of the steel sheet, the angle and position of the illumination, the position of the camera, and the like, the light appears differently from the normal portion at the defective portion, which is captured by the camera as an imaged signal. The captured signal can be fully shaped in the data processing system to identify defect information. The data processing system uses DSP-equipped image processing system for high speed real-time processing, and DSP-specific image processing library is used. In addition, an encoder is used to synchronize the operation of the camera and the steel sheet being transferred.

Hereinafter, the apparatus of the present invention will be described in more detail with reference to the accompanying drawings.

1 is a schematic diagram of the overall configuration of an apparatus according to the present invention, and FIG.

In FIG. 1, the speed of the moving steel sheet 1 is at most 1 m / sec, and the width of the steel sheet is for example 1.2 m. Two guide rolls 2 were installed to prevent measurement noise caused by vibration while the steel sheet 1 was advanced. Monochromatic light from the monochromatic light source 4 is irradiated to the steel sheet 1 at an angle of 30 to 60 degrees in a box 3 in which external light is blocked from entering, and an image of a defect portion on the surface of the steel sheet 1 is a high-speed line. It is detected by the scan camera 5. The encoder 6 is attached to the guide roll 2 for synchronization between the moving speed of the steel sheet 1 and the photographing operation of the camera 5. The image detected from the surface of the steel sheet 1 appears as comprehensive information on the defects on the surface of the steel sheet 1 in the image processing system 7. Window for forming a light line in the width direction so as to select monochromatic light having a wavelength of 1.0 μm from the light blocking box 3 for preventing other external light from entering the steel sheet 1 and to distribute it uniformly to the surface of the steel sheet ( 8) is constructed and installed so that the line of briquettes is irradiated to the steel sheet 1 passing through a predetermined position in the box 3. At this time, the monochromatic light is irradiated to the steel sheet 1 at an angle between 30 and 60 degrees through a proper adjusting device so as to easily distinguish whether the defect is a protrusion or a depression, and the line scan camera 5 is fixed at 45 degrees. Install. The incidence angle of the monochromatic light is selected from 30 to 60 degrees because light incident on the surface of the steel sheet 1 is formed with different shades at the depressions or projections, and these defects are easily detected and detected.

2 shows a configuration of a line scan camera and an image processing in the apparatus of the present invention. The line scan camera 5 used contains 4096 image elements, and the minimum defect size on the surface of the steel sheet 1 is 0.1 mm x 0.1 when the width of the steel sheet 1 is 1.2 m and the speed is up to 1 m / sec. In the illustrated example, three line scan cameras 5 are connected in parallel in the width direction of the steel sheet in consideration of the width direction of the steel sheet in order to detect a defect of mm. The incident monochromatic light 10 forms an optical line 11 of the shape shown at the surface, and the camera 5 captures an image with respect to the steel plate where the optical line 11 is formed. Numerous data on the steel plate surface captured and input through such a line scan camera system is configured to allow data processing by an image processing system composed of a plurality of image processing boards 9, for example.

The apparatus of the present invention provides the effect of continuously detecting fine defects on a moving steel sheet more precisely than before by the above-described configuration and action.

Claims (5)

Box 3 for irradiating the steel sheet 1 through the inside of the state in which the inflow of external light is blocked, and a box to irradiate a monochromatic light of a predetermined width on the steel sheet 1 proceeding inside the box 3 (3) a monochromatic light source 4 and an optical line forming window 8 provided therein, a line scan camera 5 provided inside the box 3 so as to photograph at a high speed a portion of the steel sheet 1 to which the monochromatic light is irradiated; Cold-rolled steel sheet surface defect detection device characterized in that it comprises an image processing system (7) for processing the image information from the camera (5). 2. The apparatus of claim 1, wherein the apparatus further comprises a guide roll (2) for preventing vibration of the steel sheet (1). 2. The line scan camera (5) according to claim 1, wherein the line scan camera (5) consists of a plurality of line scan cameras arranged in the width direction of the steel plate (1), and the image processing system (7) is electrically connected to the line scan cameras. Cold rolled steel sheet surface defect detection device, characterized in that consisting of a plurality of image processing boards (9) connected. The cold-rolled steel sheet surface defect detecting apparatus according to claim 1, wherein the monochromatic light is irradiated at an angle of incidence in the range of 30 to 60 degrees with respect to the steel sheet. The cold rolled steel sheet according to any one of claims 1 to 4, characterized in that the apparatus also comprises an encoder (6) arranged to synchronize the moving speed of the steel sheet (1) with the photographing operation of the camera (5). Surface defect detector.