| 摘要 |
PURPOSE:To make the maintenance of an electron gun easy by fitting the movable X ray shielding member to a supporting cylinder and by covering completely the opening part of a fixed X ray shielding member. CONSTITUTION:A fixed X ray shielding member 11 is provided on the inner wall of a welding chamber 1 and movable X ray shielding member 12 is fitted to a supporting part 7 as well. A sliding base 4 is moved in vertical direction with the movement of an electron gun 5 and in this case movable X ray shielding member 12 is moved as well together. The shielding member 12 cuts off completely the opening part of the fixed shielding member 11 irrespective of its position, therefore. With this method the opening area of the shielding member 1 can be minimized and the X ray shielding cover of the electron gun 5 is disused. The maintenance of the electron gun 5 is thus made easy. |
