Typically, a wafer board panel comprises layers of wood flakes or wafers formed into a composite structure using a resinous binder. The preparation of wafer board panels is complex, but broadly consists of two principal stages. The first stage comprises the preparation of the wafers and the admixing thereof with the binder to form a loose layer or mat; the second stage involves subsequent compression and heating of the mat to cure the resin and form the consolidated panel.
At present, wafer board is manufactured in the form of planar or flat sheets. The cost of production of such wafer board panels is economically attractive, because a low grade timber may be utilized as the raw feedstock. Wafer board is a recognized structural panel, finding wide application in the construction industry, particularly as a plywood substitute in residential construction.
Inherent disadvantages of wafer board panels, of planar configuration, reside in the low structural stiffness and strength thereof, which fall much below that of the more costly plywood.
Improvement in the performance characteristics of flat wafer board panels has been attained by optimization of such parameters as wafer orientation, wafer geometry, resin selection and content, and the like. However, existing technology would appear to have exhausted these possibilities of increasing structural strength.
In an attempt to improve the flexural strength characteristics of wafer board panels, applicants contemplated the provision of a wafer board panel having a corrugated configuration. The fundamental concept of corrugating materials to thereby improve the structural properties is not a novel one.
A method which readily comes to mind, for providing a corrugated wafer board panel involves placing a flat resin-coated wood flake mat between corrugated platens and heating and compressing the mat therebetween. However, this approach has not been successful because the mat must elongate to assume the form of the corrugated platens. Due to the unlocked state of the wafers, they tend to shift in certain portions of the mat during the compression-elongation operation and the compressed product is characterized by density variations.
Thus, to form the mat by compression and heating of a planar mat between corrugated platens results in a panel of non-uniform density because of the freely displaceable characteristics of the flakes. Alteration of the mat from the planar to the corrugated configuration entails `stretching` or increasing the length thereof, with resulting uneveness in the density thereof occurring.