| 摘要 |
PURPOSE:To obtain an outflow part of fused glass which is simple, precise and capable of allowing it to intermittently flow out therethrough by providing an outflow controlling means for adjusting the pressure of gas which is brought into contact with fused glass between the connecting part of a storage tank of fused glass and the tip of the outflow part thereof. CONSTITUTION:The raw material of optical glass is introduced into a storage tank 2 of fused glass and heated with a temp. controlling means 4 to obtain fused optical glass G. Then this glass G is allowed to flow to a first-dthird parts 6a-6c having required cross-sectional areas and heated with the temp. controlling means 8, 10, 12 to adjust it at required viscosity and allowed to successively flow. On the other hand, the pressure of inert gas such as gaseous nitrogen introduced into a pipe 20a is changed with an outflow controlling means 20 consisting of a piston 20e and a bellows 20c or the like and the pressure exerted to glass G in corporated in the second part 6b is adjusted and thereby glass (g) having about logeta=4 viscosity is flowed out intermittently (e.g. interval of 15-60sec) through an outflow port 14 at every required volume (e.g. 5cm<3>).
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