| 摘要 |
PURPOSE:To decrease a crack fault generated during curving work or after finishing a product by forming a straight part at the node part of a glass bulb. CONSTITUTION:A stem 2 having electrodes on both ends of a linear glass bulb 1 is sealed while forming a node part having a straight part 3 of 1-3.5mm. near the bottom part of the sealed part. After softening said glass bulb 1 by heating in a heating furnace, the lower end of the glass bulb 1 is supported by a mounting pin 5 in order to fix the positional relation to a chuck supporting the node part at the upper end of the node part 4. Next, the central part of the straight part 3 of the node part 4 is grasped, for instance, by a chuck 6 having a curved surface of 0.7-0.8mm. radius at the tip part. Then, after making the mounting pin 5 to descend down to the dotted position as illustrated, a curving roller (not illustrated) is made to roll upward to have the glass bulb curved into the ring shape and further to manufacture a ring-shaped fluorescent lamp by a usual method. |
