| 摘要 |
PURPOSE:To obtain a glass bulb having an uniform thickness by softening and elongating the lower part of the vertically suspended glass bulb through heating, and then elongating glass bulb mainly in the upper part compulsorily or by dead load after heating the whole glass and then bending the glass bulb into a ring form. CONSTITUTION:A straight glass bulb 1 is fitted onto he working head 6 of a bending apparatus for manufacturing a ring-shaped fluorescent lamp 5, and at first the lower part of said bulb 1 is heated in a preparatory heating furnace 7. When the glass bulb is softened to the degree where elongation is permitted, the bulb edge neck part 9 is held by the vertically movable holding device 8 of a bulb elongating apparatus, and the bulb is elongated by a prescribed length l1 by a compulsory force. Then, the whole bulb 1 is heated and softened in a main heating furnace 10 and elongated by the length l2 to permit its contact with a stopper 3 by the dead load of the bulb 1 or a compulsory force. Then, the neck part 9 at the bulb edge is held by a bulb edge holder 4 on the basis of the stopper 3, and the whole bulb is rolled into a ring form, elongated a little, and shaping is executed, maintaining a constant amount of elongation in the part A close to the upper edge, the part B close to the center, and the part C close to the lower edge. |
