Introduction: This series of products is adsorbed on the surface of the magnetic conductive workpiece and can crawl freely without tracks and manned guidance. It can realize automatic tracking welding at all positions, including horizontal welding, flat welding, vertical welding, overhead welding, and curved surface welding of large-scale structures. And it can realize multi-layer and multi-pass welding to make the welding seams smooth, ensure a good welding quality, improve the welding efficiency, reduce costs and improve working conditions.