To prevent the generation of welding abnormality in the flash butt welding process of a strip by measuring and monitoring the interval between a preceeding stock and succeeding stock, the shape of each plate and the difference of each plate level with a two-dimensional range finder before welding.
Two two-dimensional range finders 14 and 15 are arranged so as to freely take in and take out to a position opposite to the upper and lower surface of the butting part between the back end of the preceeding stock S1 and the front end of the succeeding stock S2, the interval between the front end and back end, the shape of the plate, the different amount of the plate level and the shape of the cut cross section are measured using one side of the two-dimensional range finder 14 (15) after cutting with a rotary shear, and the irregular amount in the trimming surface and the residual amount of the bead are measured using simultaneously two two-dimensional range finders 14 and 15 after trimming with a trimmer 13. Whereby, the welding abnormality is monitored.
FUKUTAKA YOSHIKI
MURAKAMI AKIRA
AKIYAMA KOICHI
