Method and apparatus for forming webs

Claim 1

IN THE MANUFACTURE OF CONTINUOUS FIBROUS WEBS, UNDER PRESSURE-FORMING CONDITIONS, BY THE USE OF A CONFINED FLOWING STREAM OF A FLUID SUSPENSION OF FIBROUS MATERIAL WHICH IS OF GENERALLY RECTANGULAR CROSS SECTIONAL OUTLINE, HAVING A WEB-FORMING PORTION AND AT LEAST ONE OTHER PORTION WHICH FORMS A BOUNDARY LAYER OF SAID FLOWING STREAM, SAID WEB-FORMING PORTION BEING CAUSED TO FLOW INTO CONTACT WITH A MOVING, FLUID-PERMEABLE FORMING MEMBER IN A WEB-FORMING REGION IN SUCH MANNER THAT THE LONGITUDINAL AXIS OF SAID WEB-FORMING PORTION EXTENDS IN A DIRECTION GENERALLY PARALLEL TO THE DIRECTION OF MOVEMENT OF SAID FORMING MEMBER AS SAID MEMBER PASSES THROUGH THE WEBFORMING REGION, THE IMPROVEMENT WHICH CONSISTS IN SELECTIVELY INCREASING THE FLUID PRESSURE IN THE WEB-FORMING PORTION OF THE FLOWING STREAM IN THE WEB-FORMING REGION BY THE CONTROLLED CONVERSION OF VELOCITY ENERGY TO PRESSURE ENERGY WITHIN SAID FLOWING STREAM TO THEREBY EFFECT A PREDETERMINED DISTRIBUTION OF FLUID PRESSURE WITHIN THE WEBFORMING PORTION OF SAID FLOWING STREAM IN SAID WEB-FORMING REGION, SHEARING A LAYER OF SAID FLOWING STREAM ABRUPTLY AWAY FROM THE ZONE OF INCREASED FIBER CONCENTRATION IN SAID WEB-FORMING PORTION IMMEDIATELY ADJACENT SAID FORMING MEMBER SO THAT SECONDARY FLOW CURRENTS ARE DIVERTED AWAY FROM THE FRESHLY FORMED WEB, SAID SHEARING BEING ACCOMPLISHED AT A POINT WHERE THE FORMING AND DEWATERING OF SAID WEB IS SUBSTANTIALLY COMPLETE AND WITHOUT SUBSTANTIALLY ALTERING THE DIRECTION OF MOVEMENT OF THE REMAINING UNDIVERTED MATERIAL, AND CAUSING SAID WEB SUPPORTED BY SAID FORMING MEMBER TO MOVE INTO AN UNCONFINED AREA OPEN TO THE ATMOSPHERE IMMEDIATELY BEYOND THE POINT OF SAID SHEARING ACTION WITHOUT ANY SUBSTANTIAL FURTHER DEPOSITION OF FIBERS ON SAID WEB BEYOND SAID POINT.