Method for heating an advancing yarn

A method for the melt spinning of a highly oriented yarn composed of a plurality of continuous filaments of a thermoplastic polymer or the like, and comprising the steps of

• extruding a polymeric melt through a plurality of orifices of a spinning die so as to provide a plurality of separate filaments,
• withdrawing the filaments emerging from the spinning die while cooling the withdrawn filaments in a cooling zone below said spinning die to a temperature below their solidification temperature to provide a bundle of advancing solidified filaments,
• advancing the solidified bundle from the cooling zone at a speed sufficient to apply a resistance force to the bundle from contact with the ambient air,
• applying a drawing force to the bundle of advancing solidified filaments and against said resistance force to effect drawing of the filaments in a drawing zone and so as to impart a draw ratio of at least 1:2 to the filaments and so as to produce a highly oriented resulting yarn, and with the drawing zone defining an initial drawing point at which the drawing commences,
• heating the bundle of advancing solidified filaments by guiding the same through a tubular heating tube, and including positioning the tube so that said initial drawing point is located within said tube, and selecting the temperature and length of the tube and positioning the heating tube so that the initial drawing point is located at a selected position within the length of the tube so as to achieve desirable physical properties in the resulting yarn, and
• winding the resulting yarn onto a cross-wound package.