Rieter

Effects of the arrangement of the bobbins in two rows

Index

The arrangement of the take-up packages is rather unusual for a spinning machine. The bobbins are not arranged individually or in a single row. Instead, they are arranged in the delivery section in two rows one behind the other, with the bobbins of one row offset relative to those of the other.
This arrangement is extremely economical in terms of space, but has several disadvantages: the design is made more complicated; operation of the machine is made less convenient; and automation is hindered. The technological disadvantages are still more significant.

The angle of approach of the roving to the flyer top is different for the two rows (Fig. 3, α). This results in different rolling conditions at the entry point of the roving to the flyer top. There is also a difference in the angles of withdrawal (β) of the two rovings at the front cylinder and thus in the lengths of the spinning triangles. Another effect is produced by the difference in the unsupported lengths (L), i.e. the lengths between the drafting arrangement and the flyer top (L1 + L2).

Together, these differences result in uneven take-up of twist, different degrees of integration of the fibers and finally to variations in roving fineness between the front and rear rows. Modern roving frames no longer suffer this technological disadvantage. In fact, the flyers in the rear row are equipped with an extension, which eliminates the above-mentioned differences in angles (Fig. 4).

Fig. 3 – Thread path geometry at the delivery and flyer top

Fig. 4 – Thread path in modern roving frames