Filamentary core for an elastic yarn, elastic composite yarn, textile fabric and apparatus and method for manufacturing said elastic yarn

A method for producing a filamentary core, comprising:

• providing separately at least two elastic performance filaments configured to be stretchable at least about 2 times its package length and have at least 90% up to 100% elastic recovery after having being released from a stretching 2 times its package length;
• and
• providing a force shifting mechanism configured to boost a bouncing back force of the filamentary core, said force shifting mechanism defining a predetermined shifting point depending on a rate of elastic elongation of the filamentary core, wherein:
• said force shifting mechanism is preset such that, when initiating elongation of the filamentary core, the elastic recovery force applied by the elongated filamentary core is realized by at least one active elastic performance filament of the at least two elastic performance filaments and the other of the at least two elastic performance filaments remains in a passive status according to which said other of the at least two elastic performance filaments essentially does not render a recovery force,
• said shifting point is set to be at a predetermined elongation rate of the filamentary core upon which the other of the at least two elastic performance filaments is initiated to become active in applying a recovery force, and
• said force shifting point is set for an elongation of the filamentary core of more than 0% or 5% of a package length of the filamentary core and less than 100% of the package length of the filamentary core.

An arrangement for producing a filamentary core, comprising:

• at least two separate supplies configured to separately supply at least two elastic performance filaments;
• and
• at least one draft ratio generator for the at least two elastic performance filaments, said at least one draft ratio generator being configured to be adjusted or adjustable in that said at least two elastic performance filaments are introduced in an elastic composite yarn at different draft ratios differing from each other in at least 0.1, 0.2, 0.3, 0.4, 0.5, 0.8 or 1.0,
• wherein the at least one draft ratio generator comprises, for each elastic performance filament:
• a pair of rotatably supported bars having a cylindrical outside surface, and a weight role in a rolling contact to the rotatably supported bars to receive the elastic performance filament;
• and
• wherein the pair of rotatably support bars are driven by at least one or two drives, as servo engines, and/or each bar of the pair of rotatably supported bars is associated to one drive, as one servo engine, the force transfer connection between the respective bar and the drive being by a belt.