ELECTRON BEAM WELDING METHOD

PURPOSE:To prevent surely the generation of welding defects by cutting off the beam current and acceleration voltage on detection of the abnormal rise of the beam current and by restoring to the original beam current and acceleration voltage after the beam stoppage time by the specified equation. CONSTITUTION:When an over-beam current is flowed it is detected by a beam current detector 18 and becomes more then the prescribed value against the set value of a beam current setter 19. A beam cut-off adjusting circuit 23 turns off momentarily the grid voltage of a triode 14. Now the beam current and acceleration voltage are instantaneously cut off. Consequently the spark discharge of the inside of an electron gun 13 is lost. The beam cut-off adjusting circuit 23 restores the beam current and acceleration voltage upto the set value of beam current setter 19 and acceleration voltage setter 11 after executing the OFF motion for the beam cut-off (stoppage) only for the certain time t with K/V (K: prescribed value of a constant setter 22, V: detected value of a welding speed detector 21) as the upper limit. The welding is thus succeeded and the generation of the welding defects due to the suspension in welding is prevented.