| 摘要 |
PURPOSE:To enhance illuminance and to make illuminance distribution uniform, in a non-contact type detector of the surface flaws of a continuous hot cast slab, by providing lighting instruments on both sides of an image sensor, which detects the flaws, and intersection the light axes of the instruments at one point at the center of the slab. CONSTITUTION:A cast slab 3 is inserted between an upper roll 8 and a lower roll 10. An image sensor 12 is provided directly over the slab 3. Two pairs of lighting instruments 14a and 14b are provided on both sides of the image sensor 12, which one pair on one side. The light axes of the instruments are intersected at one point at the center of the slab 3. The lighting instruments 14a and 14b place a linear light source at the inside of a parabolic columnar mirror. One end of the linear light source is made to be the focal point of the parabolic columnar mirror. The other end is deviated from the focal point slightly. In this structure of the lighting instruments, the average illuminance and the distribution of the uniformity ratio of illuminance becomes uniform with the intersection of the light axes as the center. Therefore, the illuminance of the slab 3 is high and the distribution of the illuminance becomes uniform. Thus the flaws on the slab surface can be minutely picked up. |
