| Abstrakt: |
This study focuses on the changes in twist distribution within a yarn false-twist texturing system that might be expected as processing speeds are increased to ultra high levels. The first order distribution of twist within a false-twist system at conventional processing speeds is well known and well attested. On start-up, twist is inserted equally on the upstream and downstream sides. However, as the yarn passes through the system, the twist in the downstream side is suppressed by twist of the opposite handedness passing over from the upstream side. On the upstream side twist levels increase until equilibrium is reached between twist creation and twist loss to the downstream side. Second order effects at conventional processing speeds have been well documented. It has been shown that, in practice, upstream twist may not be uniform. For example, it has been demonstrated that higher levels of twist are generated within the heater zone. Furthermore, although most work has naturally concentrated on the upstream zone, some have observed alternate S and Z twist develop on the downstream side during surging or start-up. Although the results were obtained for a low twist, low tension system, it is believed that they are an indicator for the expected twist distribution for high-twist, draw texturing systems at velocities which approach twist propagation speed and where dynamic conditions prevail. |
