Forming roll for twin wire papermaking with axially aligned wave-shaped ribs

Claim 1

In a paper-making machine of the type having a rotatable roll, an inNer foraminous belt and an outer foraminous belt movable along endless paths that include a convergent run in which they converge in the direction of their movement toward the roll surface and a conjoint run in which they run conjointly around a portion of the roll surface with the inner belt in engagement with the roll surface, and a stock delivery nozzle for introducing a ribbon-like jet of paper-making stock under pressure between the belts at the convergent run thereof, whereby a layer of stock is received between the belts and moves with them along their conjoint run for drainage outwardly through the outer belt and inwardly through the inner belt along such conjoint run, an improvement wherein the rotatable roll comprises a cylindrical body and a multiplicity of generally corrugatedshaped ribs extending radially outwardly from and generally longitudinally along the surface of the cylindrical body, all ribs being of substantially identical wave shape along their lengths and the ribs being substantially equally spaced-apart circumferentially of the body to define a multiplicity of zig-zag regular wave-like cells of uniform size and shape, each of which cells has a dimension longitudinally of the roll that is substantially greater than its dimension circumferentially of the roll, and all of which cells have medial axes that at corresponding points circumferentially of the roll intersect radial cross-sectional planes of the roll at substantially the same angle such that the wave forms of all cells are substantially in phase longitudinally of the roll.