Apparatus for drawing fibers by fluid means

Abstract

An apparatus is described for drawing at least one and preferably a multiplicity of continuous fibers through a drawing funnel. The drawing funnel is positioned with its inlet at a predetermined distance from the source from which monofilament is to be drawn. The funnel is provided with an aerodynamically smoothly converging inlet on an upstream section thereof. This converging inlet accelerates the flow of fluid, preferably air or other gaseous medium, and creates laminar flow of that fluid. Means are provided to establish a pressure differential over the length of the funnel and cause the fluid flow through the funnel. Laminar flow is utilized in the converging inlet and preferably over the length of the drawing funnel, to inhibit physical damage to the continuous fiber. The funnel inlet is located to insure that the fiber is fully solidified or finished, before a pulling force is exerted thereon. That pulling force is generated by friction of the moving stream of fluid in contact with the surface of the filament. The converging inlet accelerates the laminar flow of fluid to establish a velocity differential in which the fluid velocity exceeds the velocity of the continuous fiber. The velocity differential supports laminar flow throughout the drawing funnel, and generates the frictionally developed pulling force. Preferably, the converging inlet to the drawing funnel is positioned at a distance in the range from about 5 inches to about 15 inches from a source of heat-softened fiber forming material, preferably a glass or mineral composition. The drawing funnel is configured in one embodiment so as to provide substantially constant velocity of the fluid flow over the length of the drawing funnel. In another preferred embodiment of this apparatus, the drawing funnel is configured to have a substantially constant cross-sectional area over the length of that funnel. Further yet, the drawing funnel preferably has a rectangular slot-like cross-section to pass a multiplicity of individual fibers. A diffuser section normally is joined to the discharge end of the drawing funnel. This diffuser section decelerates the fluid flow and continuous fiber carried thereby, thus enabling collection of the attenuated fiber in a predetermined form, say on a collet, in a bucket, as a felted mat, or the like.

Dependencies are inferred from the claim text.