Method for forming glass fibers

Abstract

A glass fiber attenuation apparatus and process wherein molten glass is supplied from a molten glass body to an orifice plate at substantially atmospheric pressure to prevent molten glass flow through an orifice at which attenuation has ceased, thus permitting continuation of the attenuation process despite breakouts at individual orifices. The preferred embodiment of the method includes the steps of cooling the orifice plate undersurface to a non-wetting temperature and delivering molten glass to the orifice plate at a pressure less than the internal, surface tension-generated pressure of any bead formed on the undersurface of the orifice plate upon attenuation cessation at that orifice. The preferred embodiment of the apparatus includes a perforate pressure plate immersed in the body of molten glass and superimposed over the orifice plate to effect a pressure drop upon normal attenuation flow which is sufficient to reduce the pressure immediately above the orifice plate to substantially atmospheric pressure or, in any event, to a pressure less than the internal pressure of a bead or globule formed on attenuation cessation at an orifice. The orifice plate may be of either the planar, non-tipped type or of the tipped type, and the orifice plate may be cooled to the appropriate temperature either by gas flow cooling directed at the undersurface of the orifice plate or by fin shields.