| 摘要 |
PURPOSE:To improve the quality of a weld zone by forming a spot of the smallest diameter of a beam to a welding member, then executing welding while moving the spot and ending the welding in the down slope of the movement of the spot. CONSTITUTION:An anode 3 is disposed below an electrode filament 1 and a Wehnelt electrode 2 and a focusing coil 4 and a polarizing coil 5 of an electron beam are respectively disposed. A metallic plate 10 which is a member to be welded is fixed in an atmosphere of a prescribed vacuum degree and first the plate 20 is irradiated with the electron beam to form the spot of the min. diameter. The DC current changing in accordance with the size of the welding spot is then supplied to the polarizing coil 5 to move the beam and to execute welding. The DC current is gradually decreased upon lapse of the prescribed time to end the welding in the down slope. Since the welding spot 11a forms the stripe-patterned bead, the generation of a weld crack is prevented. The quality of the weld zone is, therefore improved. |
