Abstract: A method and apparatus for manufacturing a corrugated product in which the corrugated mediums are bonded at their flute tips with no intervening liner. A corrugated belt or belts is provided to withdraw the bonded and aligned mediums in a substantially straight line from the pair of corrugating rolls which are synchronised to achieve the alignment and bonding of the flute tips of the two mediums. The corrugated belt provides support and constraint for the bonded mediums until the bond is set or until a liner sheet is bonded to one of the mediums.

Abstract: A structural corrugated paper board for use in forming boxes which incorporates two fluted layers bonded peak to peak enclosed in two outer liners. By increasing board thickness and concentrating strength in the outer liners and eliminating the inner liner between the fluted layers improved edge compression and overall strength per unit weight is improved.