BUILD-UP WELDING DEVICE FOR HARD FACING

PURPOSE:To provide a titled device which prevents delamination in a build-up part and improves the wear resistance thereof by the constitution in which the circumferential surface of a cylindrical body is subjected continuously to build-up welding while welding current is periodically fluctuated and the rotating speed of a cylindrical body is fluctuated. CONSTITUTION:Large and small pulses P1, P2 are respectively alternately and periodically generated at every large and small generation time by a sequence part 12 and a pulse signal generator 9 and are inputted to a welding control part 10 and a rotating speed control part 11 with a multi-layer buil-up welding device which builds up continuously a molten metal on the circumferential surface of a cylindrical body 7 by a welding torch 2 while said body 7 is rotated around the axis thereof by a rotating device 5. A welding control part 10 passes the large and small welding currents in accordance with the pulses P1, P2 and a rotating speed control part 11 controls the rotating speed of the body 7 to high and low speeds in accordance with P1, P2. Weld beads 8 of which the bead width changes alternately to large and small sizes are thus formed on the circumferential surface of the body 7, by which the weld crack thereof is prevented, the delamination inthe build-up part is prevented and the wear resistance is improved.