FORMING BELT FOR THREE-DIMENSIONAL FORMING APPLICATIONS

A method and apparatus for forming a layer structure, such as an airlaid fibrous web, include a supplying mechanism (24) for providing a stream of particulate material, such as fibers. Also included is a substantially endless, foraminous forming belt (28) which has an appointed outward surface (30) and a minimun thickness of at least about 3/16 inch. A selected contour is formed into the outward surface (30) of the belt at selected locations, and the contour is distributed along a lengthwise machine-direction of the forming belt. The forming belt is configured to flex along a thickness direction thereof, and to recoverably bend and substantially straighten when traveling along a selected belt path circuit. A conveying mechanism (42) moves the forming belt past the supplying mechanism along a forming path section (44) of the belt circuit which is substantially straight, and moves the forming belt along a return path section (46) of the belt circuit which includes curved portions therein. A vacuum mechanism (48) draws a flow of air through the thickness of the forming belt to lay the particulate material onto the forming belt to form a layer structure, such as a web, having a top surface and a belt-side surface thereon. The web is thereby produced with a selected non-uniform thickness contour which is formed along the belt-side surface of the fibrous web. A driving mechanism moves the forming belt along the machine-direction at a selected speed, and a transporting mechanism (94) removes the contoured web from the forming belt. L'invention concerne un procédé et un dispositif permettant de former une structure en couche, telle une bande fibreuse à couche appliquée par jet d'air. Ce dispositif comprend un système d'alimentation (24) qui fournit un flux de matériau particulaire, tel que des fibres. Le dispositif comprend en outre une bande de conformation foraminée (28) sensiblement continue qui présente une surface extérieure (30) déterminée et dont l'épaisseur minimale est au moins approximativement de 3/16 pouces. Un contour sélectionné est formé à l'intérieur de la surface extérieure (30) de la courroie à des endroits sélectionnés et le contour est réparti le long du sens machine longitudinal de la courroie de conformation. Sa configuration lui permet de s'infléchir dans le sens de son épaisseur, de se courber par rétablissement et de se redresser sensiblement lorsqu'elle suit une trajectoire sélectionnée. Un système transporteur (42) fait passer la courroi