METHOD AND APPARATUS FOR MAKING OPTICAL FIBRES

摘要

Method and apparatus for producing glass products of predetermined shape. In the method, a perform is introduced into a furnace and heated to a temperature above the softening point of the glass. The heated portion is subjected to tensile forces and drawn from the furnace through an outlet opening. During processing, inert gas is fed into the furnace. According to the invention, the concentration of gaseous impurities in the furnace is maintained on the same level as in the inert gas fed into the oven. To prevent inflow of undesired gaseous components from the ambient air, a diffusion barrier is established by generating a barrier flow of inert gas in the inlet or outlet openings. This barrier flow has a direction of flow, which is opposite to the direction of the diffusion. The invention provides non-contacting sealing between the furnace and the preform while optimizing the consumption of protective gas. The invention also allows for simultaneous rotation of the preform.