| 摘要 |
PURPOSE:To prevent the generation of electric discharge in an electron gun in beam welding by interrupting a high voltage electric circuit constituted of a high voltage power source and the electron gun which is the load thereof for optional time by changing the degree of vacuum in the electron gun thereby stopping the operation of the electron gun. CONSTITUTION:A high voltage power source 1, electron gun 2 and a vacuum tube 17 constitute a main high voltage circuit. The gun 2 is attached to a vacuum chamber 10 for welding and the inside of the chamber 10 and a vacuum chamber 7 for the electron gun is continuously evacuated with vacuum pumps 9, 8. The gun 2 controls the thermoelectron released by the cathodic heating by a cathode power source 3 with a bias power source 4 and welds the material 6 in the chamber 10. The pipe 17 is made electrically conductive in a steady state but when the degree of vacuum of the chamber 7 decreases just prior to the generation of the electric discharge owing to entry of gas and molecules of metallic vapor into the chamber 7, the output from a detector 11 for said decrease changes and is compared with a voltage setter 12 in a circuit 13 which emits the output signal of DC. Then a multivibrator 14 and a transistor 16 operate and the output of a control grid power source 15 is applied to the tube 17, by which the high pressure circuit is interrupted. The output of the vibrator 14 is made zero after the interruption and the operation of the gun is resumed. |
