| 摘要 |
An arrangement for controlling feeding in a bottom vacuum corrugation feeder when sheets with curl are encountered includes a timer and a sensor for detecting the negative pressure level in a vacuum plenum of the vacuum feeder. The vacuum pressure sensor gives a signal proportional to the degree of vacuum behind feeder belt holes that are in communication with the vacuum plenum. The vacuum pressure sensor is used to measure the instantaneous level of vacuum in the plenum, as well as, to detect the point at which sheet acquisition has occurred. The sensor is interrogated at predetermined intervals during the acquisition portion of the feed cycle. At each interval, the current pressure level detected in the vacuum plenum by the vacuum pressure sensor is compared to a reference value for that interval. Depending on whether the pressure is above or below the reference level, a controller will either decrease or increase air knife pressure or vacuum pressure in order to maintain sheet acquisition time within a nominal window regardless of stack size, paper weight or paper curl.
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