Sliver drawing unit gives measurements of the drafting forces on the sliver in the drafting field, directly or indirectly, to adjust the pressures applied by the upper rollers in the paired drawing rollers

摘要

To operate a sliver drawing unit, for a spinner, the sliver (FV) is drawn in a drafting field (10) between at least two pairs of rollers (2,5;3,6). The drafting forces on the sliver are measured directly or indirectly. The measurements are used to vary the pressures applied by the upper roller in each pair. To operate a sliver drawing unit, the measured drafting forces on the sliver are used to adjust the position of a pressure rod (20) in the drafting field, or the spread of the sliver in front of the drawing unit. The upstream upper roller is shifted while its lower roller remains static, and the deflection is converted into a measurement signal which is characteristic of the drafting force, to be used to alter the control intervention point in at least one drafting field or the main drafting field. The drafting force can also be measured by the deflection of the pressure rod by the moving sliver, or at the torque of at least one drawing roller, or the power consumption of the drive motor, or the power used for the drive of at least one roller, or the forces at the roller drive transmission. The measured values, as correction values derived from the measurements and/or the time curve are displayed for at least one parameter e.g. the fiber staple length. The measured values and/or their derived correction values are stored electronically, to be accessed as quality characteristics for the sliver. The torque take-up is measured at least at one roller at the roller bearing mounting and/or the power take-up by the motor, and the draft force is computed by a comparison of the drive torques when there is a sliver at the drawing unit and when there is no sliver present. An air humidifier decreases or increases the fiber friction in the sliver. An Independent claim is included for a sliver drawing unit with a drafting field formed between at least two pairs of rollers. The drafting forces on the sliver are measured directly or indirectly.