Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1996-09-18
2001-03-20
Gray, Linda L. (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S250000, C156S267000, C156S299000, C144S350000, C144S345000, C144S346000, C144S355000, C144S344000, C052S455000
Reexamination Certificate
active
06203653
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to wooden blanks and mouldings, and more particularly to mouldings that have substrates covered by a machinable wooden veneer. A reengineered rip saw as described herein preferably is used to form a plurality of lineal mouldings in parallel simultaneously.
The use of mouldings such as base (floorboard skirting), flat and split door jambs, crown (ceiling surrounds), rabbeted jambs (frames), brick mould, and casing (door and window surrounds), are well known. Mouldings generally are decorative, and provide architectural detail. Some mouldings, however, support light loads such as door jambs that support the hinges and doors. It is important that the wood used in the mouldings be of at least a quality corresponding to the type of finish use desired, and the type of load supported. For example, if the mouldings are to be left natural or varnished, then the wood is usually desired to be clear and bright, free of knots, fungus stains, pitch, wood discolerations, glued joints, or other visible blemishes. Such mouldings are known in the construction business as “clear solid grade lineal mouldings,” or simply “solid clear mouldings.”
Mouldings intended to be covered by paint (or something else that hides the glue joint, color, grain or defect of the wood) are known as paint grade mouldings. The construction industry uses paint grade mouldings in most applications. Using a lower grade knotty or defective or discolored woods, or otherwise imperfect wood, in the fabrication of paint grade mouldings is especially desirable considering that higher quality clear and bright grade woods are generally less plentiful and more expensive. Lower grade woods are less expensive than solid clear mouldings, and the finger joint manufacturing process involved in the fabrication of paint grade mouldings, removes defects that are unpaintable in finished mouldings. The use of paint grade moulding results in a lower cost of the finished moulding applications because long clear bright lengths of natural finished wood are not required. In recent years, the use of clear solid grade mouldings has declined while the use of paint grade mouldings has become more common.
Finger joint moulding is produced using a fifty year old process created to provide paint grade moulding in desired dimensions. Each finger joint moulding is formed by a lengthy multi-step process that includes: 1) ripping strips from a thick plank of wood, 2) cross cutting blocks of paintable and finger-jointable defect-free segments out of each strip by removing those segments having knots, splits, blemishes, or other defects, 3) occasionally reripping the cut blocks strips to a narrower width to remove any broken or wane edges, 4) finger jointing by machining and glueing the resulting accumulated clear blocks to form finger joint blanks of the desired length and dimension, 5) resawing if necessary, with a band saw or rip saw the finger joint blanks in a desired dimension or beveled shape, 6) passing the resulting blank through a multi-headed profiled knife moulder in lineal fashion to form mouldings in their final cross sectional contoured shape, and 7) precision trimming and dado processing the mouldings into the final desired lengths of the moulding. The typical remaining steps for finger joint moulding processing, before shipping, are occasional sanding or patching, priming or painting, and packaging.
Though finger joint moulding is a widely accepted and used paint grade moulding, there are several undesirable characteristics associated with the prior art techniques used to manufacture finger joint mouldings. First, the production of finger joint mouldings is slow, labor intensive, and generates much wood waste. Even with skilled craftsmen and modem machines, approximately 45 to 50 percent cumulatively of the original wood volume used is lost (as sawdust, shavings, and defect blocks) during the many processing stages. The entire board footage volume of finished finger joint moulding profiles fabricated is constituted by an equivilent volume of high quality clear solid wood. The lumber materials used in the fabrication of finger joint moulding are expensive and of limited availability. The finished product being formed from solid bright clear wood is likewise expensive and in limited supply.
Second, each discrete section of wood or blank used in finger joint moulding is composed from multiple smaller blocks or discrete wood sections. Therefore, each discrete wood section is susceptible to its own natural characteristic tendencies of warping, splitting, bowing, cupping, twisting, and other problems common to other discrete lengths of wood. Wood moulding that warps, cracks, or otherwise distorts is difficult and frustrating to work with, and increases scrap. Additional unpredictable waste is generated during the manufacturing process. If the process exposes a defect previously hidden inside the wood and it becomes apparent that a section or block is defective in that manner after it is fabricated into a blank, it can usually result in the entire blank being deemed defective and subject to complete remanufacture to remove such newly apparent defects.
A third undesirable characteristic of prior art finger joint mouldings, shared with other paint grade mouldings and varnish grade mouldings, is that each moulding piece usually has to be moulded separately. Rarely are more than two pieces machined simultaneously in one moulding machine, and two pieces may be machined simultaneously only when the profile has a very small cross sectional dimension as most moulders are not wider than eight inches, and all moulders are not wider than twelve inches. Machining one or two work-pieces at a time (especially when using modern and expensive moulders) is costly in both machine time and labor costs. Such slow, individual, work processing adds to the expense of the moulding significantly and usually results in smaller mouldings being only slightly less costly than mouldings having larger cross sections, or solid clear grade lineal mouldings formed from higher quality wood. Since each moulding piece is moulded separately and since cross cutting is a separate operation, each piece also has to be handled, measured, and cross cut by itself.
Other mouldings are formed as substrates that have veneers covering some or all of their surfaces. Veneers are much more common in furniture component construction than in moulding fabrication. In prior art veneer mouldings, an inexpensive substrate of wood, or other material such as medium density fiberboard, is machined or formed in a quality fashion to the desired shape of the final moulding. A thin strip of veneer (usually cut or sliced from a high quality wood) is then bent or contoured in a shape that conforms directly to the surface of the substrate. The veneer is then adhered to the exposed surfaces of the substrate. If done correctly, veneer mouldings can have an attractive appearance resembling, but being less costly than, solid clear wood mouldings. Veneer moulding is more expensive than finger joint paint grade mouldings. The use of veneer moldings is usually commercially reserved to low volumes of high quality expensive veneer hardwood species where solid wood of that species is difficult or too costly to obtain.
Present veneer mouldings have several shortcomings, however. To form a thin veneer into certain generally commercial standard industry household moulding profiles or desired angles or shapes, the veneer has to be bent sharply to conform to sharply angled contours of the profile. Most veneers are formed from a wood that cannot adapt to very sharp bending, and attempting to bend them sharply causes cracking. Such cracking may occur after the moulding leaves the factory, and perhaps during installation of the moulding. However, most cracking occurs in manufacturing. Sharp angles are therefore not usually found on veneered mouldings. In addition, the adhesive used to attach the veneer to the substrate may fail, allowing the veneer to peel away. The use of
Gray Linda L.
Pretty & Schroeder
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