Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-02-02
2001-08-07
Dawson, Robert (Department: 1712)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C428S035900, C428S036500, C428S358000, C428S613000
Reexamination Certificate
active
06270600
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to methods and apparatus for reinforcing various structures and, more specifically, relates to reinforced channel-shaped members.
BACKGROUND OF THE INVENTION
In a number of applications, light-weight, high-strength structural members are required, for example in motor vehicles and aircraft as well as in various devices such as home appliances and the like. A number of composite materials have been proposed in the past as structural members, such as exotic light-weight alloys. In most applications, however, mass reduction must be balanced against the cost of the product to the consumer. Thus, there is a need for providing strength without significantly increasing materials and labor costs. Moreover, reinforcement techniques are needed which can be adapted to existing geometries of structural parts, obviating any requirement for fundamental design changes.
As examples of reinforcement techniques, the present inventor has disclosed a number of metal/plastic composite structures for use in reinforcing motor vehicles components. In U.S. Pat. No. 4,901,500, entitled “Light-weight Composite Beam,” a reinforcing beam for a vehicle door is disclosed which comprises an open channel-shaped metal member having a longitudinal cavity which is filled with a thermoset or thermoplastic resin-based material. In U.S. Pat. No. 4,908,930, entitled, “Method of Making a Torsion Bar,” a hollow torsion bar reinforced by a mixture of resin with filler is described. The tube is cut to length and charged with a resin-based material.
In U.S. Pat. No. 4,751,249, entitled, “Reinforcement Insert for a Structural Member with Method of Making and Using the Same,” a precast reinforcement insert for structural members is provided which is formed of a plurality of pellets containing a thermoset resin with a blowing agent. The precast member is expanded and cured in place in the structural member. In U.S. Pat. No. 4,978,562, entitled, “Composite Tubular Door Beam Reinforced with a Syntactic Foam Core Localized at the Mid Span of the Tube,” a composite door beam is described which has a resin based core that occupies not more than one-third of the bore of a metal tube.
In U.S. Pat. No. 5,575,526, entitled “Composite Laminate Beam for Automotive Body Construction,” a hollow laminate beam characterized by high stiffness-to-mass ratio and having an outer portion which is separated from an inner tube by a thin layer of structural foam is described. In U.S. Pat. No. 5,755,486, a W-shaped carrier insert reinforcement which carries a foam body is described for use in reinforcing a hollow beam.
In U.S. patent application Ser. No. 08/644,389, filed May 10, 1996, entitled “INTERNAL REINFORCEMENT FOR HOLLOW STRUCTURAL ELEMENTS,” now abandoned, the present inventor discloses an I-beam reinforcement member which includes an external foam layer. The I-beam, as in the case of most of the foregoing reinforcements, involves a preformed structural insert which is then inserted into a hollow structural member.
It is also known to increase strength of a laminate structure by bonding together flat metal plates using an intervening layer of resin. For example, it is known to form a metal laminate sheet for use as a floor panel member which comprises a pair of flat metal sheets having an intervening layer of asphalt or elastic polymer.
Although filling the entirety of a section with plastic foam does significantly increase section stiffness (at least when high-density foams are utilized), this technique also may significantly increase mass and thus part weight, which, as stated, is an undesirable feature in most applications. In addition, filling a section entirely with foam may be prohibitively expensive and creates a large heat sink. And, although increasing the metal gauge of a section or adding localized metal reinforcements will increase stiffness, as the metal thickness increases, it is more difficult to form the part due to limitations of metal forming machines.
Accordingly, it would be desirable to provide a low-cost technique for reinforcing a channel-shaped structural member without proportionately increasing the mass. It would also be desirable to provide a method of reinforcing an existing channel-shaped member which does not require any fundamental design changes to the member. The present invention provides channel-shaped members which have increased strength with moderate increases in mass and without the use of high volumes of expensive resins. The present invention further provides a method for reinforcing existing structural parts without redesigning the geometry of the part. It has been found that the present invention increases section stiffness and provides vibration dampening in channel-shaped sections in a highly efficient and reproducible manner.
SUMMARY OF THE INVENTION
In one aspect the present invention provides a reinforced channel-shaped member. The channel-shaped member is preferably a stamping or the like which defines a channel. The channel generally has a length which is greater than its width. The channel-shaped member is typically formed of metal or plastic. A layer of expanded structural foam is disposed in the channel. The shape of the structural foam matches that of the channel-shaped stamping; that is, the foam has one surface which is bonded to and conforms to the wall of the channel-shaped member defining the channel and another (opposed) surface which is itself channel-shaped. An insert is disposed and bonded to the layer of structural foam. The insert geometry mates with that of the structural foam. The insert is a metal foil or plastic and has a thickness of from 0.002 to 0.100 inch.
In another aspect two reinforced channel shaped members are formed and are then joined together to form a reinforced tube.
In still another aspect the present invention provides a method of reinforcing a structural part which includes the steps of forming a laminated structure having a layer of unexpanded, uncured foam-forming resin, and a layer comprising a metal or plastic carrier sheet; placing the laminate on a part having a non-planar geometry; conforming the laminate to the geometry of the non-planar part; and thermally expanding and bonding the resin to the part.
In one aspect the method of the present invention reinforces a channel-shaped structure through the steps of extruding a planar layer of thermally-expandable structural resin onto the surface of a release liner; placing a planar foil on the resin to form a foil/resin laminate having a release layer; die cutting the material to shape; removing the release liner; placing the foil/resin laminate over a channel-shaped structural member such that the resin layer is facing the part; pressing the foil/resin laminate structure into the channel such that the resin layer contacts the part in the channel; trimming away any excess foil/resin laminate from the part; and heating the part to thermally expand the thermally expandable resin and to securely bond the resin to the foil and to the channel-shaped member.
These and other advantages and objects of the present invention will now be more fully described with reference to the drawings.
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Dawson Robert
Harper Stephen D.
Henkel Corporation
Jaeschke Wayne C.
Pezzner Harold
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