Rieter

Operating principle

Index

The Dref-3000 spinning system (Fig. 30 and Fig. 31) produces bundled yarn according to the friction-spinning principle. Basically, it is a Dref-2000 process expanded to accommodate a drafting arrangement (2) before the spinning drums (4).
A drawframe sliver (1) with a linear density of 2.5 - 3.5 ktex is passed into this three-line double-apron drafting arrangement (2). The strand (3) resulting from the draft of about 100 - 150 proceeds from the delivery of the drafting arrangement to the convergent region between the two perforated drums (4). A pair of take-off rollers (7) draws this strand through the convergent region of the perforated drums and out of the spinning zone.
The coherent fiber strand is nipped at the take-off rollers (7) and the drafting arrangement (2) and is rotated between these points by a pair of perforated drums (4). It is therefore false-twisted between the nips. This means that turns of twist are present between the drafting arrangement and the drums, but not between the drums and the withdrawal rollers. If this state of affairs were to continue, the strand would fall apart. Before this can happen, staple fibers are fed in free flight from above (5) into the convergent region between the drums. Owing to the rotation of the perforated drums, these incoming fibers wrap themselves around the horizontally moving strand. A bundled yarn is formed.

The fiber cloud (5) arriving from above emerges from a second drafting arrangement with two opening rollers. This arrangement is fed with four to six drawframe slivers with a linear density of 2.5 - 3.5 ktex.

From the take-off rollers (7) the yarn passes to a winding unit. The yarn leaves the machine in the form of crosswound packages.

Fig. 30 – The Dref-3 spinning principle

Fig. 31 – The Dref-3000 spinning unit