ELECTRON BEAM WELDING METHOD OF LARGE-SIZED STRUCTURE

PURPOSE:To perform electron beam welding of a large-sized structure while maintaining stably the vacuum degree in the structure by erecting and stacking two cylindrical structures, attaching a partition wall for shielding in the upper structure, evacuating the inside of the structure to a vacuum from the bottom end of the lower structure and subjecting both structures to electron beam welding along the joint thereof. CONSTITUTION:The 2nd structure B is placed via a lower seal 5 on a surface plate 1, and further the 1st structure S is stacked thereon. The outside circumference of the peripheral joint X between the structure A and the structure B is vacuum sealed by seal welding, etc. and is further subjected to X- ray sealing. After an inside sealing partition wall 9 is attached in the structure A, the inside of the structure is evacuated 4 to a vacuum from the bottom end of the structure B through an evacuating port 3. While an electron gun 8 is rotated and moved, an electron beam 7 is bombarded against the joint X so that the joint is subjected to electron beam welding from the inside circumference. The structures A, B are thereafter pulled upward, and the 3rd structure C is placed via a seal 5 on the plate 1 and the structures A, B are stucked thereon. The peripheral joint Y between the structures A, B and the structure C is subjected to electron beam welding from the inside by the same method as the above- described method.