| 摘要 |
PURPOSE:To obtain a good electron shielding effect inspite of a deficient part in an end hat caused by arc welding by installing an auxiliary end hat over an end hat, while thereby forming such configuration to cover the part of arc welding from the cathode side. CONSTITUTION:An auxiliary end hat 11 made of a relatively thin Mo plate is piled on the first end hat 9 made of Mo or the like having the shape of a ring plate. Said auxiliary end hat 11 has three pieces of tungue-shaped and inwardly protruding projections 12 on the inside circumference and the inside diameter (a) including the projection 12 is made to be somewhat larger than the outside diameter of the central short cylindrical part 9a of the first end hat 9 while the inside diameter (b) not including the projection 12 is made to be approximately same as the spiral outside diameter of cathode 1. Accordingly, as the deficient part 10 due to melting generated during the process of welding is covered by the auxiliary end hat 11 from the cathode side, the desired electron shielding effect can be satisfied. |
