Rieter

Influence on the ends down rate

Index

This reasoning is based on a comparison of a short triangle (Fig. 87, left) and a longer one (Fig. 87, right), and on the behavior of two fibers (F in the middle and f at the edge of the triangle).
Both fibers are longer than the spinning triangle (distance K/N to G). Whereas fiber F undergoes no change in direction of movement during its passage through the spinning triangle, fiber f is bent to a greater or lesser extent at N (angle Φ), increasing distance N-G. Consequently, the tension forces from the yarn cause an elongation of fiber f. So if bending angle Φ is large (for short spinning triangles), the elongation of fiber f is very high. That is why the tension forces (Fig. 87, FS) of the yarn during the formation of the yarn pass mainly into edge fibers f (in zone ZS, Fig. 88, left). Fibers F in the core remain almost free of elongation and hence of tension.

Therefore almost the entire tension force of the yarn in the balloon acts only on a certain part of the fibers in the spinning triangle, i.e. on the edge fibers. As a result, when tension peaks due to shocks or uneven running from traveler or balloon act on the spinning triangle, these few fibers cannot bear the full load; they break or the fiber strand slips apart, causing an end break. That is why end breaks normally occur within the spinning triangle from outside (edge) to inside (core). This danger is always present with a short spinning triangle. Owing to the large angle φ, the tensile forces are distributed very unevenly; high on the edge fibers (zone ZS) and much less on the central fibers (zone ZO). Distribution is much better (zones ZL) with a long triangle. As a result it can be stated that spinning conditions are improved by reducing angle φ. A long spinning triangle therefore shows a more uniform distribution of forces (ZL). Since tension is distributed over the entire fiber mass in these conditions, fewer end breaks are the obvious result.

Fig. 87 – Length of the spinning triangle

Fig. 88 – Spinning triangle – forces acting on the fibers: 1 short staple triangle; 2 long staple triangle