| 摘要 |
PROBLEM TO BE SOLVED: To shorten the time required for forming without causing deformation, crack or the like by the thermal stress during forming in a glass bottomed tube. SOLUTION: In an apparatus M for forming a glass tube in which a glass bottomed tube 3 having an inserted core mold 2 is passed through a heating furnace 4 while reducing the pressure of the inside of the glass bottomed tube, and is shrunk and deformed so that the outer shape of the core mold 2 is transferred, there is provided an upper heating zone 4a and a lower heating zone 4b which are independently capable of setting the temperature each other in the passing direction of the glass bottomed tube 3 inside the heating furnace 4, the temperature of the upper heating zone 4a that is the entering side of the bottomed end 3b of the glass bottomed tube 3 is set at a forming temperature, the temperature of the lower heating zone 4b that is the leaving side of the glass bottomed tube 3 is set at a slowly cooling temperature, thereby heating and slowly cooling of the glass bottomed tube 3 are conducted within the heating furnace 4, wherein the occurrence of the deformation and the crack of the glass bottomed tube 3 by the thermal stress is prevented even when the heating furnace 4 is moved at a relatively large speed against the glass bottomed tube 3. COPYRIGHT: (C)2009,JPO&INPIT
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