| 摘要 |
A method of forming continuous glass filaments of less than 0.0018 inch diameter comprises maintaining molten glass in a melter 60 (Fig. 2, not shown), heating the glass in the melter, flowing the glass from the melter at a comparatively slow rate through a conditioning region 70 of substantial depth, progressively and continuously reducing the temperature of the molten material as it moves through the conditioning region, maintaining the glass in said region for a sufficient time to promote a high efficiency of laminar flow and attain a high degree of homogeneity, flowing the molten glass through orifices formed in depending projections 100 having very thin marginal edges to promote the rapid formation of a bead of glass of small size to thereby reduce the bead drop time, gathering the filaments trailing the descending beads into a strand and winding the strand on a collector. Glass marbles 29, Fig. 1 (not shown), are matered into the melting zone 60 by a revolving drum 41 at a rate determined by a programmer 56 from information from a probe 53 detecting the glass level in the zone 60. A perforated current conducting heater screen 76 of inverted V-shape and made of an alloy of platinum and rhodium is disposed across the melting unit between the melting zone 60 and conditioning zone 70. Melting occurs in zone 60 and the glass temperature increases till just below screen 76. The zone 70 is of considerably less width than zone 60. The glass temperature gradually decreases down through zone 70 in order to promote glass movement in laminar planes and effectively refine and homogenize the glass. The design of the melter unit is such as to provide a glass residence time of about 1 1/2 hours. The floor of zone 70 is formed with a plurality of dependent hollow projections 100 (Fig. 5, not shown) made of platinum/rhodium alloy. Disposed between each row of dependent tips 100 is a fin 108 attached to a manifold 104 through which cooling water flows. Thus these fins 108 condition and stabilize the viscosity of the glass in the tips 100. To produce filaments of not greater than 0.00018 inch diameter the dependent tips 100 should be so constructed as to have a central metering passage D1 of diameter 0.045 inch, an end counterbore D2 of diameter not exceeding 0.060 inch, and a tip face well thickness D6 of not more than 0.005 inch. The diameter of the metering passage D1 is dependent upon the diameter and length of the counterbore. The distance between each dependent projection is sufficient to permit the beads of glass to be in close reaction but out of contact in order to prevent flooding. It is preferable that the tips 100 be not more than 0.18 inch long. As this length decreases so should the metering diameter D1. The above construction allows for a bead drop time of about 1 minute. The filaments are sized and wound in the conventional manner. |
