| 摘要 |
PURPOSE:To eliminate the need for prior working of pipe end parts by welding both side parts of one pipe in centering at the point where deformation is largest out of the end part of said pipe beforehand to the cylindrical part of the other pipe, flowing AC current between the pipes, and pressurizing the pipes roughly to a desired shape then subjecting the pipes to main welding to each other. CONSTITUTION:In the 1st stage, one pipe 1 and the other pipe 2 are combined in such a way that the end part 1A of the former and the cylindrical part 2A of the latter abut on each other. In the 2nd stage, DC current is flowed between the pipes 1 and 2 under exertion of pressure, whereby these are welded auxiliarily. In the 3rd stage, AC current is flowed between the pipes 1 and 2 under exertion of the pressure smaller than before, whereby the end part of the pipe 1 is softened and is deformed according to the shape of the cylindrical part of the pipe 2. In the 4th stage, main welding current is flowed between the pipes 1 and 2 under exertion of pressure so that the entire end part of the pipe 1 is welded to the cylindrical part of the pipe 2. |
