Rieter

Draw-off tubes with and without ceramic insert (TWISTstop)

Index

The draw-off tube is positioned immediately behind the draw-off nozzle and is used to guide the yarn on its removal from the spinning box. In order to divert the yarn being withdrawn horizontally from the rotor to the take-up unit positioned vertically above it, the draw-off tube is bent at an angle of between 30° and 60°, depending on the type of spinning box. This diversion zone in the draw-off tube acts as a second twist accumulation element and supports the twist retention generated by the draw-off nozzle in the rotor. The greater the angle of the bend, i.e. the angle of wrap of this diversion zone, the greater the twist retention and the higher the spinning stability. This twist accumulation effect can be reinforced by fitting ceramic twist retention elements (TWISTstop or Torque stop – ceramic ribs arranged laterally) of differing intensity on the contact surface in the radius of the bend (Fig. 86).

The greater the angle of diversion and the higher the friction caused by the additional ceramic inserts, the greater the twist retention, the more intensive the twist propagation into the rotor groove and the higher the spinning stability. This favors the manufacture of especially soft-twisted knitting yarns, since the high twist retention enables low twist multiplyers to be set without adversely affecting spinning stability.

The twist accumulation elements are designed as clips and can be replaced very easily, as required. The design of the internal profile ranges from smooth to 3 lateral ribs in the radius of the bend.

The best spinning results as regards yarn quality, yarn structure and spinning stability are always achieved when the draw-off nozzle and draw-off tube are ideally coordinated with each other .

Fig. 86 – Thread draw-off tube (a) with interchangeable twist retention element (b)