Vacuum apparatus having textured web-facing surface for controlling the rate of application of vacuum pressure in a through air drying papermaking process

摘要

A papermaking vacuum apparatus having a web-facing surface adapted to support a papermaking belt and comprising a head, a body and at least one vacuum slot disposed in the head and defining an aperture on the web-facing surface. The vacuum slot is in fluid communication with the web-facing surface and extends from the web-facing surface to the body which is in further fluid communication with a vacuum source. The web-facing surface comprises a textured area in the region of the web-facing surface juxtaposed with the aperture defined by the vacuum slot. This textured area creates a leakage of at least about 35 Marlatts at a pressure differential of 7 inches of Mercury. This leakage eliminates the vacuum seal between a smooth backside of the papermaking belt and the web-facing surface of the vacuum apparatus.