Process for continuously producing ribbons of corrugated fibrous material, includes: starting from a continuous ribbon of fibrous material having transversal extensibility of not less than 8%, advancing the ribbon between a pair of forming rollers presenting ribs alternating with grooves, and having a center distance such that the ribs of one roller are partially housed within the grooves of the other roller and define between them a corrugated interspace having a thickness greater than the thickness of said ribbon and a width substantially equal to the width of the flat ribbon, which at the exit presents a longitudinal undulation obtained by transversal stretching thereof, passing the longitudinally corrugated ribbon thus obtained between a pair of stabilizing rollers with complementary ribs and grooves interpenetrating such as to present a distance between them less than the thickness of the ribbon thereby subjecting the ribbon to a stabilization compression of the obtained corrugations.

A forming device for gathering the width of a traveling web is disclosed. The forming device includes opposing arrays of flute-forming bars that can be interlaced to define therebetween a longitudinal flute-forming labyrinth effective to reduce the width of a web traveling therethrough by a preselected take-up ratio. The flute-forming bars are curved beginning at an entry end of the forming device such that they converge in a lateral direction as they proceed in the machine direction. In this manner, individual elements of the web traveling between the respective arrays in the machine direction follow contour lines along the curved bars or between adjacent ones of the curved bars so that no such element crosses any flute-forming bar in the cross-machine direction as the web travels and is fluted. A corrugating die for introducing a near-net shape to the intermediate-fluted web is also disclosed, as are a corrugating line incorporating these operations and methods for its operation.

A forming device for gathering the width of a traveling web is disclosed. The forming device includes opposing arrays of flute-forming bars that can be interlaced to define therebetween a longitudinal flute-forming labyrinth effective to reduce the width of a web traveling therethrough by a preselected take-up ratio. The flute-forming bars are curved beginning at an entry end of the forming device such that they converge in a lateral direction as they proceed in the machine direction. In this manner, individual elements of the web traveling between the respective arrays in the machine direction follow contour lines along the curved bars or between adjacent ones of the curved bars so that no such element crosses any flute-forming bar in the cross-machine direction as the web travels and is fluted. A corrugating die for introducing a near-net shape to the intermediate-fluted web is also disclosed, as are a corrugating line incorporating these operations and methods for its operation.

An arrangement for producing embossed cushioning material from an initially flat material comprises an embossing device for providing a plurality of embossed protrusions to the material, an undulating device comprising undulated forming spaces which creates undulations in the initially flat material prior to the undulated material being provided to the embossing device, and a conveying means for conveying the initially flat material along a transport path in a continuous process through the undulated forming spaces. It is that suggested that the undulating device, seen in the direction of the transport path, comprises at least two stages each comprising an undulated forming space, the undulated forming space of a downstream stage differing in number and/or height of undulations from the undulated forming space of an upstream stage.

A system and method for producing a board product made from paper products that have embossed medium that features an improved structural profile. The improved structural profile may include a triangular flute pattern wherein each flute may exhibit a first linear leg support and a second linear leg support that each support a center apex structure. The apex may have a substantially flat portion that is configured to engage a facing. As such, the board product may further include one or more facings that are adhesively coupled to the embossed medium. Further, the apex of each “triangle” may also have a groove or channel for receiving an adhesive in a continuous and uniform manner.

A process for making a continuous web of a longitudinally corrugated fibrous material includes passing the web between a rigid cylinder having circumferential grooves that are flanked and shaped to define a substantially corrugated profile on substantially on the entire thickness of the web, and a presser which has an external layer made of an elastically compressible material and which is maintained adherent to the rigid cylinder so as to cause the continuous web to penetrate into the grooves and thus obtain the corrugations, At the same time, the continuous web is subjected to a reduction of the speed of the surface in contact with the presser with respect to the speed of the surface in contact with the rigid cylinder so as to have a longitudinally corrugated pattern on both surfaces and transverse ripples at least at the corrugated surface that was in contact with the rigid cylinder.

A process for making a continuous web of a longitudinally corrugated fibrous material includes passing the web between a rigid cylinder having circumferential grooves that are flanked and shaped to define a substantially corrugated profile on substantially on the entire thickness of the web, and a presser which has an external layer made of an elastically compressible material and which is maintained adherent to the rigid cylinder so as to cause the continuous web to penetrate into the grooves and thus obtain the corrugations, At the same time, the continuous web is subjected to a reduction of the speed of the surface in contact with the presser with respect to the speed of the surface in contact with the rigid cylinder so as to have a longitudinally corrugated pattern on both surfaces and transverse ripples at least at the corrugated surface that was in contact with the rigid cylinder.

An apparatus for introducing transverse trapezoidal corrugations into a traveling web is provided, and includes a plurality of corrugating rollers for imparting corrugations to the web. In disclosed embodiments four such rollers are provided in a roller train defining respective first, second and third nips therebetween, wherein the teeth of the first and second rollers have rounded distal faces and those of the third and fourth rollers have flattened distal faces. Methods of yielding a trapezoidal corrugated web also are disclosed.

A forming device for gathering the width of a traveling web is disclosed. The forming device includes opposing arrays of flute-forming bars that can be interlaced to define therebetween a longitudinal flute-forming labyrinth effective to reduce the width of a web traveling therethrough by a preselected take-up ratio. The flute-forming bars are curved beginning at an entry end of the forming device such that they converge in a lateral direction as they proceed in the machine direction. In this manner, individual elements of the web traveling between the respective arrays in the machine direction follow contour lines along the curved bars or between adjacent ones of the curved bars so that no such element crosses any flute-forming bar in the cross-machine direction as the web travels and is fluted. A corrugating die for introducing a near-net shape to the intermediate-fluted web is also disclosed, as are a corrugating line incorporating these operations and methods for its operation.

A forming device for gathering the width of a traveling web is disclosed. The forming device includes opposing arrays of flute-forming bars that can be interlaced to define therebetween a longitudinal flute-forming labyrinth effective to reduce the width of a web traveling therethrough by a preselected take-up ratio. The flute-forming bars are curved beginning at an entry end of the forming device such that they converge in a lateral direction as they proceed in the machine direction. In this manner, individual elements of the web traveling between the respective arrays in the machine direction follow contour lines along the curved bars or between adjacent ones of the curved bars so that no such element crosses any flute-forming bar in the cross-machine direction as the web travels and is fluted. A corrugating die for introducing a near-net shape to the intermediate-fluted web is also disclosed, as are a corrugating line incorporating these operations and methods for its operation.