GB1219418A - The manufacture of fibres, filaments and films form molten materials - Google Patents

Abstract

1,219,418. Continuous casting. MONSANTO CO. 4 Dec., 1967 [6 Dec., 1966], No. 55120/67. Heading B3F. [Also in Division C1] Fibres, filaments or films, including rods, ribbons or wires are formed by streaming a melt through an orifice, e.g. by extrusion through a ruby die 18, and stabilizing the stream against break-up before solidification (by forming a thin film on it by reaction, decomposition or deposition as described in Specification 1,153,577) and also applying a deceleration, e.g. by passage through a denser or counterflowing atmosphere or by applying an electrostatic field or by interposition of a plate 36, at a position downstream of a point where if applied it would disrupt the stream and upstream of a point where tensile forces would break it up if the deceleration were not applied. The melt may be non-metal (see Division C1). In the spinning apparatus shown, material such as Pb-Sn is melted, e.g. under vacuum, by resistance heaters 20 or an induction heater, in a chamber 16 and the temperature monitored by a thermocouple 24. By operation of a valve 26 the chamber may be alternately evacuated and supplied with argon to extrude the melt controllably, through a 100 micron orifice 20 in the ruby jewel 18, into a preevacuated glass column 27, supplied with a spin gas mixture of helium or nitrogen (with a small volume of oxygen) through holes 32 in a ring 30, to form a stabilizing oxide film on the stream. During evacuation (through a connection 34), the bottom of the glass column 27 is temporarily closed and extrusion may start before the introduction of the spin gas. The flow rate of the oxygen into the column may be varied. The stream is decelerated by impact on the collection plate 36 which is adjustable vertically and may be tilted. The continuity of the stream between the melt crucible 10 and the plate 36 may be monitored for determination of spinning conditions by a simple electrical continuity testing circuit, Fig. 3 (not shown). As described in Specification 1,197,972, to avoid undue surface expansion of the stream and subsequent weakening of the stabilizing film, the die orifice 20 may be a short bore, i.e. it may have a minimum cross-sectional area extending over a length less than five times the major dimension of that cross-section. As described in Specification 1,210,920, the drag on the stream due to the spin gas is controlled to prevent it causing deviation of the stream from moving up the stream.