Rieter

Leveling drawframes with open-loop control

Index

The total volume of all slivers is measured at the infeed (Fig. 15) and adjustment is effected with the appropriate time delay in the main drafting zone, i.e. the extent of the change is retained in a storage device until the measured deviation arrives at the drafting point. Detection is usually carried out mechanically (rollers with grooves, bores or steps) or by capacitive sensors.
This system permits very precise leveling of very short lengths. A second advantage is the ability to measure far greater sliver masses due to the lower infeed speed (corresponding to the amount of draft). Recording becomes more precise. In practice, drawframe leveling using open-loop control is now predominant.

Fig. 15 – Leveling drawframe with open-loop control