LASER BEAM WELDING DEVICE FOR JOINING STEEL PLATES

PURPOSE:To join steel plates after correcting a camber error by measuring the central position of the steel plates from the cutting signal in the stage of laser beam cutting then making the centerline of the other steel plate to coincide with the centerline of one steel plate. CONSTITUTION:Working heads 7, 8 on an outlet side and inlet side are started from a reference position S and the distances l1, l2 from the start of cutting steel plates 3, 6 and the distances L1, L2 up to the end of cutting are measured with rotary encoders 13, 15 on the basis of the cutting signal such as light from detectors 10, 11. A operator 22 operates the difference delta0 in the distances from the centerline S of the plates 3, 6 and inputs the output e0 thereof to an amplifier 23. The amplifier 23 controls a motor 20 by the differential output (e0-e) from the output (e) of a rotary encoder 21 so as to attain delta0=0, thereby making the centerline of the plate 6 to coincide with the centerline of the preceding plate 3. The plates 3, 6 are welded by a head 7 after cutting and the joining of the steel plates with good quality is accomplished by the above-mentioned method.