Weyerhaeuser Company Limited

Richard E Wagner

Ronald C Wilderman

John S Selby

John W Kerns

Earl D Hasenwinkle

Kendall H Bassett

Alkivadis G Dimakis

David W Park

Alkiviadis G Dimakis

A method for bonding composite wood products comprises using a PMDI adhesive modified with a polar compound such as a lower alkylene carbonate or triacetin with a combination of conductive thermal heat and radio frequency energy. Propylene carbonate is a preferred modifier. Press temperatures and pressing times may be significantly reduced from those using either unmodified PMDI adhesives or the modified adhesives without radio frequency energy. Laminated veneer products 38 mm in thickness can be pressed at 110&deg;-120&deg; C. in as little as 7 minutes using radio frequency energy at a level of about 32 kw/m .

Method for bonding composite wood products

Engineered structural wood products particularly useful in critical applications such as joists, headers, and beams where longer lengths, greater widths, and higher and predictable stress ratings may be required and to a method for making the wood products. Most logs by nature are radially anisotropic, having wood of higher density and stiffness in their outer portion adjacent the bark than is found in the inner portion. The logs are machined to segregate the denser, stiffer outer wood. A first generally rectangular component is formed from the less dense inner wood. Second generally rectangular components are formed from the stiffer outer wood. Second components are adhesively bonded to at least one edge of the first component, more usually to opposite edges. The stiffer wood is thus specifically placed where it will contribute most effectively to the properties of the product. The product is analogous to an I-beam in which the lower density first component serves as the web and the higher density second component as the flange portion The products can be handled in use in identical fashion to solid sawn lumber. They are characterized by much less variation in their stiffness than solid sawn visually or machine graded products and can be made in a wide range of width, thickness, and length.

Method for manufacture of structural wood products

The invention comprises engineered structural wood products particularly useful in critical applications such as joists, headers, and beams where longer lengths, greater widths, and higher and predictable stress ratings may be required. The invention is also directed to a method for making the wood products. Most logs by nature are radially anisotropic, having wood of higher density and stiffness in their outer portion adjacent the bark than is found in the inner portion. The logs are machined to segregate the denser, stiffer outer wood. A first generally rectangular component is formed from the less dense inner wood. Second generally rectangular components are formed from the stiffer outer wood. Second components are adhesively bonded to at least one edge of the first component, more usually to opposite edges. The stiffer wood is thus specifically placed where it will contribute most effectively to the properties of the product. The product is analogous to an I-beam in which the lower density first component serves as the web and the higher density second component as the flange portion The products can be handled in use in identical fashion to solid sawn lumber. They are characterized by much less variation in their stiffness than solid sawn visually or machine graded products and can be made in a wide range of width, thickness, and length.

Engineered structural wood products

The invention is a method for producing flitches prepared from roundwood logs, a method for the manufacture of wood slices or slats from the flitches, and methods of combining the strips into composite lumber products. The methods are based in part on the concept of preparing flitches that retain the sweep or natural longitudinal curvature of the log and slicing or sawing around the sweep to prepare the slats for further conversion into composite lumber products. An opening cut is made in the log essentially following or parallel to the curve of any sweep to divide it into two approximately equal volume pieces. An opposing surfaces is machined parallel to the surface generated by the opening cut to produce a flitch. The flitches are then flattened so that the sweep curvature is made planar. They are then sliced or sawn parallel to the now planar surface to produce slats. The natural surface of the log is preferably retained on the sides of the flitches. Slats may then be edged and adhesively combined in various ways to produce composite lumber products. The method achieves an especially high yield from raw logs of products that simulate solid sawn lumber in appearance, properties, and ease of use.

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Auburn, WA, United States of America

Richard E Wagner