| 摘要 |
PROBLEM TO BE SOLVED: To make possible the detection of a butt line position with high accuracy and reliability, even in a mirrorlike butt part, and also where edge preparation is not made and the form of butt is not constant. SOLUTION: This detector comprises floodlights 1a, 1b for projecting a ray of light on a butt part, a camera device 11 for photographing the butt part, a nonlinear converter 14 for amplifying a photographing brightness level signal with a high rate within a low brightness region and with a low rate within a high brightness region, butt position detecting means 12, 10 for detecting as the butt position the dark part of an image which the amplified brightness level signal represents, and an air nozzle for spraying air upon the butt part where the scale of hot steel is removed and the mirror is exposed. Hereupon, floodlights 1a, 1b exist in the both sides of the butt line, in the direction rectangular to the butt line, and illuminate the butt part from an oblique direction respectively. The floodlight of which the edge illuminance of the butt position is higher is determined for illumination of the butt part, by switching the lighting of floodlights from one side to the other. |
