KR970047910A - Surface groove detection method of cold rolled steel sheet using laser and its device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for non-contact flaw detection of a cold rolled steel sheet using a laser. The surface roughness of the cold rolled steel sheet is set to a critical level and superimposed on a defect signal, thereby providing The purpose is to exclude the influence of surface roughness, to increase the flaw detection effect of the defect, and to easily determine the type of steel sheet defects by distinguishing the shape of the defect signal.

In order to achieve the above object, the present invention, the light beam scanned by the laser is incident to the photodetector to split into two branches, the other light beam is reflected on the specimen and incident on the photodetector to detect the surface roughness The light beam is reflected by the light shingles to be incident on the surface defect specimen of the translator, and the light beam reflected from the surface defect specimen is incident on the photodetector to detect the surface defect.

Description

Surface flaw detection method and apparatus for cold rolled steel sheet using laser

Since this is an open matter, no full text was included.

1 is a block diagram of a surface flaw detection apparatus for a cold rolled steel sheet using a laser according to the present invention

2 is a graph showing the setting of the noise level due to the surface roughness using the present invention.

3a-3f are graphs of a steel sheet surface flaw inspection example according to the present invention;

Explanation of symbols for main parts of the drawings

1: Laser 2,3: Light Garga

4,10,13,15: Lens 6,12,18: Photodetector

7: computer 8: psalms

9: Transducer 14: Spatial Filter

16: neutral filter

Claims (4)

The laser lighter 2 is installed at an angle to the laser beam 1 so that the light source is split into the specimen 8 positioned above the translator 9 and the light lighter 3 on the upper side. And a light detector 6 having a lens 4 and a band pass filter 5 installed in front of the light shingler 3 on the upper side to allow incident light to pass therethrough and detect incident light. Computer 7 for measuring the surface roughness as a signal input integrally with the photodetector is installed in front of the lens 10 and the bandpass filter 11 through which the light source reflected by 8) is transmitted. And a spatial filter formed in a circular cross-sectional area of the light beam between the two lenses 13 and 15 provided so that the light source reflected by the upper light shader 3 is formed as parallel light. 14 and a light source reflected from the specimen 8 through the spatial filter 14 The neutral filter 16 and the bandpass filter 17 which are transmitted are provided, and the computer 7 which shows the surface defect detection signal as the intensity of the light source incident on the photodetector 18 above is comprised, It is characterized by the above-mentioned. Surface flaw detection device for cold rolled steel sheet using laser. The apparatus of claim 1, wherein the neutral filter (16) adjusts the amount of light according to the sensitivity of the photo detector (18). The light beam emitted from the laser is incident on the light splitter and split into two branches. A reflected light beam is incident on the photodetector through the lens and the bandpass filter, and the other light is reflected on the specimen to reflect the lens and the bandpass filter. And detecting the surface roughness incident on the photodetector, and the light rays to be scanned are reflected through the light filter to form parallel rays by the two lenses, and the parallel rays pass through a spatial filter to determine the cross-sectional area of the rays. And forming a circular shape so as to be incident on the surface defect specimen of the translator, and the light reflected from the surface defect specimen is incident on the photodetector through the neutral filter and the band pass filter to detect the surface defect. Surface flaw detection method of the cold rolled steel sheet using the laser. The method according to claim 3, wherein the light beam scanned by the laser is incident on the light splitter and divided into two parts. The threshold level due to the surface roughness of the steel sheet is set to remove an error factor due to the surface roughness. Surface flaw detection method of a cold rolled steel sheet using a laser, characterized in that the flaw detection. ※ Note: The disclosure is based on the initial application.