ELECTRON BEAM WELDING METHOD OF LARGE-SIZED STRUCTURE

PURPOSE:To assemble stably large-sized structures by electron beam welding with an inexpensive and small-sized installation by evacuating simultaneously the inside of the butted structures to a vacuum from both sides of a partition wall for shielding and evacuating further the inside of the structre side to be welded to a high vacuum. CONSTITUTION:The 2nd copper plate 22 is erected via a vacuum seal 23 on a surface plate 19, and the 1st body plate formed with an end plate 20 and a circumferential joint 39 is stucked and butted thereon. A backing strip 28 is welded to the outside circumference of a circumferential joint 40 and at the same time a partition wall 27 for shielding is attached by means of bolts and nuts 26 via sealing rubber 25 to a sealing plate supporting plate 24 attached on the inside circumferential surface of the 1st body plate 21 to segment airtightly the inside to the upper and lower parts. Rotary pumps 35, 38 and a diffusion pump 35 are then driven to evacuate the upper side of the wall 27 to a vacuum of about 1-10Torr and the lower side to a vacuum of about 10-10Torr. While an electron beam gun 32 is driven by a driving device 29 to rotate, an electron beam 33 is irradiated to weld the joint 40.