Method for automatically compensating density or thickness variations of fiber material at textile machines, such as cards, draw frames and the like

摘要

For the automatic compensation of density or thickness variations of fiber material at textile machines there is measured the density of a fiber material mass fed to a fiber feed device and the density of the fiber material mass at the textile machine outlet. The resultant measurement signals are delivered to a control for regulating the rotational speed of a feed roll of the fiber feed device in accordance with both measured density signals. The fiber feed device comprises the feed roll and a coacting feed plate. The feed roll, although rotatable, is spatially stationary and is pivotal from a starting position in the absence of the fiber mass into an operative position into contact with an abutment when there is present a fiber mass whose density variations are to be detected. By positionally fixing the feed plate during the detection operation different forces arise, depending upon the thickness or density of the fiber mass, in the nipping zone between the feed roll and the feed plate. These different forces can be detected by different measuring elements which produce the measurement signals delivered to the control. Due to the rotational speed variation of the feed roll there are compensated irregularities in the thickness or density of the mass of fiber material in the nipping zone during transfer of the fiber mass from the feed plate to a coacting element such as a licker-in roll in the case of a card constituting the textile machine.