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A fiberboard panel is formed from at least one corrugated sheet of molded cellulose fiber material having alternating ribs and grooves. Spaced slits are cut through the ribs on one face of the sheet and terminate short of the opposite face so as to form at least one slotted portion of more flexibili

A fiberboard panel is formed from at least one corrugated sheet of molded cellulose fiber material having alternating ribs and grooves. Spaced slits are cut through the ribs on one face of the sheet and terminate short of the opposite face so as to form at least one slotted portion of more flexibility which may be bent to form a curve. The corrugated sheet is sandwiched between two flat sheets of the same material to form a composite panel. The corrugated sheet or panel is formed by a wet processing method including successive cold and hot press steps in which a wet mat is pressed between an opposing perforated platen and non-perforated, elastomeric material platen of cross-sectional shape substantially matching the desired panel shape and dimensions.

대표청구항 ▼

1. A panel, comprising: an elongated sheet of molded fiberboard material of corrugated shape having opposite first and second faces and opposite side edges, each face having a plurality of alternating, longitudinally extending ribs and grooves extending along the length of the sheet, the ribs on the

1. A panel, comprising: an elongated sheet of molded fiberboard material of corrugated shape having opposite first and second faces and opposite side edges, each face having a plurality of alternating, longitudinally extending ribs and grooves extending along the length of the sheet, the ribs on the first face each having a first peak and the ribs on the second face each having a second peak facing in the opposite direction to the first peaks;the sheet having at least one slotted portion which has a plurality of spaced slits, each slit extending lengthwise across at least a plurality of the first peaks and being cut through part of the ribs of the first face including the first peaks to a depth less than the depth of the grooves in the first face and terminating short of the second peaks of the second face;the panel being formed into at least one curve at said one, slotted portion with the slotted, first face of the sheet facing inward; andthe slits are closed at the first peaks of the ribs on the inwardly curved first face of the sheet. 2. The panel of claim 1, wherein the slotted portion extends along at least a substantial portion of the length of the sheet. 3. The panel of claim 1, wherein the slits are at a constant spacing. 4. The panel of claim 1, wherein a first group of the plurality of slits are at a first spacing and a second group of the plurality of slits are at a second spacing different from the first spacing. 5. The panel of claim 1, wherein at least some of the plurality of slits are at a variable spacing. 6. The panel of claim 1, wherein the slits are parallel and extend perpendicular to the ribs. 7. The panel of claim 1, wherein the slits extend diagonally at an angle to the ribs. 8. The panel of claim 1, wherein the sheet has a plurality of spaced slotted portions and non-slotted portions extending between said spaced slotted portions. 9. The panel of claim 8, wherein the spaced slotted portions extend alternately through the first face and the second face of the sheet. 10. The panel of claim 1, wherein the slits extend radially. 11. The panel of claim 10, wherein spaced slotted portions are provided along the length of the sheet, each slotted portion having a set of radially arranged slits, and alternating slotted portions have radial slits centered on opposite sides of the sheet. 12. The panel of claim 10, wherein spaced slotted portions are provided alternately on opposite sides of the sheet along the length of the sheet, the alternating slotted portions on opposite faces having radial slits centered on opposite sides of the sheet. 13. The panel of claim 1, wherein the sheet is formed from at least one cellulose fiber material. 14. The panel of claim 13, wherein the first and second peaks are flat and each first peak is connected to adjacent second peaks by angled webs forming opposite side faces of ribs;the angle of the web is in the range from approximately 45 degrees to 60 degrees; andthe peaks on each face have a constant center to center spacing in the range from three inches to six inches and each rib has a height in the range from 0.75 inches to 3 inches. 15. A panel, comprising: an elongated sheet of molded fiberboard material of corrugated shape having opposite first and second faces and opposite side edges, each face having a plurality of alternating, longitudinally extending ribs and grooves extending along the length of the sheet, the ribs on the first face each having a first peak and the ribs on the second face each having a second peak facing in the opposite direction to the first peaks;the sheet having at least one slotted portion which has a plurality of spaced slits, each slit extending lengthwise across at least a plurality of the first peaks and being cut through part of the ribs of the first face including the first peaks to a depth less than the depth of the grooves in the first face and terminating short of the second peaks of the second face;the panel being formed into at least one curve extending along at least part of the length of the sheet at said one, slotted portion with the slotted first face of the sheet facing inward; andthe slits are closed with adhesive at least at the first peaks of the ribs on the inwardly curved first face of the sheet.