| 摘要 |
PURPOSE:To prevent any breakdown of the bulb, which might be caused during the time when a straight glass bulb is shaped into a circular shape, by making the thickness of the part near the sealing part between the glass bulb and a stem larger, inserting the sealing part into a mold so as to form a nodal part, and shaping the glass bulb into circular form by holding the said nodal part. CONSTITUTION:A sealing part 5 is formed by heating with burner 4, a flare part 16 of a stem 1 made of lead glass and a bulb 3 made of soda glass, and the thickness of the part near the sealing part 5 is made larger owing to glass flowing down. After that, the part 5 is placed in a mold 6, and the glass bulb 3 is pushed down along the axial direction. At the same time, air or the like is charged with pressure into the bulb 3 so as to make a nodal part 9 to be formed near the sealing part 5 owing to the protruding part 7 of the mold 6. As a result, the thickness of the nodal part 9 can be made even owing to the thick part of the sealing part 5, and the breakdown which is caused when a heated and softened glass bulb 3 is shaped into circular form by holding the part 9 can be extremely minimized. |
