| 摘要 |
<p>A strip (2) of sheet wrapping material fed to a user device (4) is decoiled from a roll (3) at an upstream station (5) and then drawn by a vacuum into an equalizing chamber (7), internally of which it forms a running loop (21). The length (L) of the loop (21) is measured continuously by an analog sensing device (20) operating in conjunction with at least one bistable pressure sensor (19), located at a given height inside the chamber (7), so as to establish a range of variation outside of which the measurement is ignored; thus, the length (L) of the loop (21) can be monitored accurately by the analog sensor (20) within the selected range of variation, and maintained within this same range by the action of the pressure sensor (19). <IMAGE></p> |
