| 摘要 |
PURPOSE:To prevent breakage of water-cooled molds, etc., from occurring, by controlling an electron beam by means of electromotive force generated at the time when a conductor provided in a projection-prohibited area is projected with an electron beam in projecting a material to be heated with an electron beam. CONSTITUTION:A high voltage is impressed on a filament 7 and the electron beam 3 is emitted. A material 5 to be melted is projected with the above beam 3, while being deflected, so as to melt the material 5 to be melted. At this time, when the conductor 15 provided in the projection-prohibited area is projected with the beam 3, electromotive force is generated in the conductor 15. This electromotive force is inputted to a comparator 17, so that deflected quantity of the beam 3 is decreased or projection of the beam 3 is interrupted alternately.
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