| 摘要 |
A method and apparatus for detecting weight variations of a sliver on spinning preparatory machines, such as cards, draw frames and similar machines, at which the sliver passes through the channel or duct of a sliver funnel or trumpet. According to the invention, the sliver is initially condensed in the sliver funnel duct in order to expel entrained air. Immediately thereafter the sliver is again expanded and by virtue of such expansion there is produced at the expansion zone a pneumatic vacuum which is proportional to the weight variations of the throughpassing sliver. This generated vacuum is then advantageously employed to control an amplifier for performing a desired operation, namely a measuring or control. |
