Abstract: An apparatus for heating an advancing thermoplastic yarn led over heating ridges along a heated surface. An essential feature of the invention is that the heating ridges can be maintained at a temperature as high as that of the heating surface, in particular at a temperature sufficient for ensuring a self-cleaning effect, without damaging the yarn. If required, the heat flow on the yarn may also be regulated by adjusting the height of the heating ridges and/or by modifying the length of contact with the yarn.

Abstract: A heater (1) for an advancing thermoplastic yarn which is guided along a heated surface over ring segments (2). The flow of heat to the yarn is adjustable by changing the geometric parameters of the heat transfer.

Abstract: A yarn heating apparatus which is adapted for use in a yarn false twisting machine. The heating apparatus includes an elongate heating surface, and a plurality of yarn guide members mounted in a longitudinally spaced-apart arrangement along the length of the heating surface, for guiding an advancing yarn therealong in a laterally zigzagged path of travel which is adjacent but spaced from the heating surface.

Abstract: A yarn false twisting apparatus is disclosed which is adapted to produce a crimped composite yarn composed of an S twisted component and a Z twisted component, and wherein the full takeup capacity of the apparatus is utilized. The apparatus includes first and second false twisting units associated with each twisting position, with all of the first units being aligned in a first horizontal row extending along the length of the apparatus, and all of the second units being aligned in a second horizontal row. The two rows may be oriented with respect to each other, and the other elements of each twisting position, so that the paths of travel of the two components have an equal twisting length, and an equal cooling length.