Ferrule and use thereof for cooling a melt spun hollow glass fiber as it emerges from a spinnerette

A ferrule having utility for uniformly cooling an individual, melt-spun, hollow glass fiber, without making substantial contact with the fiber, as it issues from a spinnerette and passes downwardly through the ferrule,

• said ferrule having a rigid, heat-conductive body member, an interior wall of which defines a vertical, rectilinear passageway extending completely through said member and having the general shape of a long-stemmed, conical funnel, every cross-section of said passageway along its axis being generally circular in shape,
• said ferrule being adapted, by generally vertical cuts which form a slot therein or divide the ferrule into mating segments, so that it can be emplaced adjacent to a spinnerette and closely fitted around a moving fiber is issuing therefrom, in a position such that the axes of the fiber and passageway will coincide and the fiber will enter the funnel-shaped portion of said passageway as it leaves the spinnerette and exit from the lower terminus of the stem-shaped section,
• the width of said slot or the widths of the spaces between the mated segments being such that not more than 25 percent of any circumference of said passageway is interrupted by said slot or spaces,
• said ferrule, or each of said segments, being so composed as to have an average heat conductivity at least equal to that of graphite and being adapted to be brought into heat-transfer-effective contact with a heat sink.