Abstract:
A reinforced structural member includes a structural member and a reinforcing member, the reinforcing member being received within a cavity of the structural member and bonded thereto by thermally expansible foaming structural reinforcing material. The reinforcing member includes a carrier, a structural reinforcing material element, a directional shelf separate from the carrier, and a fastener coupling the directional shelf to the carrier. The directional shelf includes a platform which is apertured to permit the reinforcing material to foam and expand therethrough to bond the carrier directly to an adjacent wall of the structural member. At least one directional wall extends at an oblique angle to the platform to limit the expansion of the structual reinforcing material therepast during foaming. The shelf may have two directional walls which are opposing in substantially perpendicular relationship to the platform, in acute angular relationship to the platform, or diverge extending at obtuse angles to the platform.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention concerns the use of thermally expansible foaming materials, particularly thermally expansible foaming structural reinforcing materials, which are coupled to a carrier having a directional foaming shelf mounted thereon to direct the structural reinforcing material during foaming to a particular area on a surrounding structural member giving additional localized stiffness to frames, rails, structure surrounding cavities, panels and other structural members. Such a reinforcing member may be useful in architectural, automotive, aviation, marine, or any other applications where increased support or stiffness would reduce vibration, noise and/or fatigue propagation, or would provide reinforcement to enhance structural strength or provide energy management during crash, crush or impact encounters. 
     2. Description of the Prior Art 
     It has long been recognized that foamable materials may be used to bond together separate components. Structural foams, urethanes, and other thermally expansible foaming materials have been used to enhance acoustic performance and provide structural rigidity. Examples of thermally expansible structural reinforcing materials used on carriers in the automotive field are illustrated in U.S. Pat. No. 5,194,199 to Thum, U.S. Pat. No. 5,344,208 to Bien et al., and U.S. Pat. Nos. 5,575,526 and 5,755,486 to Wycech. Another example of the use of thermally expansible materials on a carrier and used primarily as a baffle composition is shown in U.S. Pat. No. 5,506,025 to Otto et al. An example of the use of a foamable material on a beam-shaped structure in a piling is shown in U.S. Pat. No. 4,019,301 to Fox et al. 
     While such showings disclose various uses of expansible materials in reinforcing, baffling and sealant applications, there has developed a need for a simplified reinforcing member which will provide stiffening and reinforcement to a surrounding structural member. The use of expansible reinforcing materials which are initially dry and non-tacky are preferred in the manufacturing context. Such materials having shipping and handling advantages; notably this type of reinforcing material does not readily adhere to shipping containers, to workers during manufacture and installation, or to other critical surfaces which may come into contact with the material. By being non-tacky, these materials will not readily retain dirt, dust or other contaminants. Additionally, these materials will not readily adversely adhere to a carrier positioned within the structural member which helps to position the reinforcing member prior to expansion of the reinforcing material. 
     SUMMARY OF THE INVENTION 
     The reinforcing member of the present invention provides significant advantages over prior carrier and expansible material combinations in manufacturing, handling and use by providing directional foaming to orient and localize the expansion and bonding of the thermally expansible foaming reinforcing material to the structural member. The reinforcing member provides support to an adjacent structural member through the foamed reinforcing material positioned on a directional foaming shelf supported by the carrier, with the carrier being configured to include a mechanical fastening element to couple the thermally expansible foaming structural reinforcing material and the directional foaming shelf to the carrier. The directional foaming shelf is apertured, whereby the reinforcing material expands therethrough during foaming and thereby bonds to the carrier, the directional foaming shelf and the surrounding structural member to provide a reinforced structural member. The carrier may be provided of various configurations and is preferably designed to provide both a mounting surface which couples to the structural member and properly locates the reinforcing material and directional foaming shelf thereon and may provide additional structural reinforcement. The use of mechanical fasteners enables the initially non-tacky structural reinforcing material and directional shelf to be positioned in various locations and orientations whereby upon activation, the reinforcing material may foam, thereby expanding to bond the carrier and the directional shelf to the surrounding structure. 
     Broadly speaking, the present invention includes a carrier which has at least one and preferably two or more surfaces for receiving a directional foaming shelf thereon, and for coupling to the structural member. The directional foaming shelf includes a platform and two or more walls angularly oriented with respect thereto. The platform includes at least one aperture to permit the thermally expansible foaming reinforcing material to flow therethrough, whereby a bond is provided between the reinforcing material and the carrier to which the shelf is attached. The walls serve to constrain and direct the reinforcing material during foaming, thereby causing the reinforcing material to engage and bond to a particular area on the structural member and further to protect some areas against engagement with the reinforcing material after foaming and expansion. This may reduce the amount of reinforcing material required in a particular application. By providing the directional foaming shelf as a separate element from the carrier, one carrier can be used for a variety of different applications by merely substituting different directional foaming shelves. The fastener may be provided separately or as a part of the carrier, and preferably provides some yield or give to permit the material to shift upon impact and provide manufacturing tolerance. In one embodiment, the fastener may be provided as a synthetic resin pin passing through the material, the directional foaming shelf and through an opening in the carrier. In another embodiment, the fastener may be provided as a tab which may be bent to grasp the material and hold it and the directional foaming shelf to the carrier. The reinforcing member is typically received in a structural member such as a rail or channel which provides a cavity for receiving the structural member therein with the reinforcing material in engagement with or proximate to the structural member prior to activation. 
     The reinforcing material is thermally expansible, either by internally created thermal energy or by the external application of heat to activate the material. As used herein, the term “thermally expansible” means to foam and thereby expand by both internally created thermal energy and the external application of heat to expand and foam the reinforcing material. The thermally expansible reinforcing material is preferably a synthetic resin-based material which foams when subjected to temperatures achieved during baking in a manufacturing process (e.g., such as during the paint and powder coat bake stage of automobile manufacturing processes). Thus, the expansion temperature of the material should be at least about 300° F. 
     The foregoing advantages to the present invention will be readily appreciated by those skilled in the art with reference to the drawings and description which follow, which are intended to be exemplary rather than limiting. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a vertical cross-sectional view taken through the reinforcing member with directional foaming shelf hereof, showing the reinforcing member received in the cavity of a structural member with the thermally expansible reinforcing material received on the directional foaming shelf coupled to a carrier by a fastener; 
     FIG. 2 is a vertical cross-sectional view of the reinforcing member taken along line  2 — 2  of FIG. 1, showing a recessed area in the upright walls of the directional foaming shelf; 
     FIG. 3 is a vertical cross-sectional member of the reinforcing member of FIG. 1 after foaming of the reinforcing material to bond the carrier, directional foaming shelf and structural member; 
     FIG. 4 is a vertical cross-sectional view similar to FIG. 1, showing a second embodiment of the reinforcing member with a directional foaming shelf having divergent walls which are oriented at an obtuse angle to the platform; 
     FIG. 5 is a vertical cross-sectional view similar to FIG. 4 showing the reinforcing member thereof after foaming of the reinforcing material to bond the carrier, directional foaming shelf and structural member; 
     FIG. 6 is a vertical cross-section view similar to FIG. 1, showing a third embodiment of the reinforcing member with a directional foaming shelf having convergent walls which are oriented at an acute angle to the platform; 
     FIG. 7 is a vertical cross-sectional view similar to FIG. 6, showing the reinforcing member thereof after foaming of the reinforcing material to bond the carrier, directional foaming shelf and structural member; 
     FIG. 8 is an exploded view of a fourth embodiment of the reinforcing member of the present invention, wherein the directional foaming shelf is provided with a perimeter wall which substantially encloses the reinforcing material and inhibit lateral expansion during foaming and a plurality of perforations to permit the reinforcing material to bond to the carrier; 
     FIG. 9 is a vertical cross-sectional view thereof, showing a fastener securing the reinforcing material to the directional foaming shelf and 
     FIG. 10 is a vertical cross-sectional view similar to FIG. 9, showing the reinforcing member after foaming of the reinforcing material to bond the carrier, directional foaming shelf and structural member. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, a structural reinforcing member  20  in accordance with the present invention is configured for positioning in a structural member  22 . The structural member  22  may include, for example, a channel  24  having a base wall and a pair of upright side walls of an automobile used as a frame member such as an engine or side rail and covered with a flat plate  26  for use as a floor pan and providing a top wall defining an enclosed cavity within the structural member. However, this is only one application for the present invention, which may be used as a component of the fuselage or wing of an aircraft, the hull or bulkhead of a boat or ship in marine applications, or as beams or components of floors, walls or ceilings of a building. 
     The reinforcing member  20  as shown in FIGS. 1-3 broadly includes a carrier  28 , thermally expansible foaming structural reinforcing material  30 , fastener  32  and at least one directional foaming shelf  34 . The reinforcing material is preferably provided as discrete reinforcing material elements  36  and  38 , received on respective directional foaming shelves  40  and  42 , each coupled to the carrier by a fastener prior to activation. The reinforcing material elements  36  and  38  are thereby held in positions sufficiently proximate the structural member  22  to permit the reinforcing material to foam, expand and bond to the carrier  28 , respective directional foaming shelves  40  and  42 , and structural member  22 . 
     In greater detail, the carrier  28  may be provided in a variety of configurations of sheet metal such as steel or aluminum, synthetic resin such as nylon, or other material having a higher melting temperature than the bake temperature to which the reinforcing member is subjected. As shown, the carrier  28  is an elongated member which is C-shaped in cross-section and has an upper arm  44  having a substantially planar first surface  45  and a lower arm  46  having a substantially planar second surface  47 , the upper arm and lower arm lying in spaced apart, parallel planes and joined by a connecting wall  48  oriented substantially perpendicular thereto. While shown in an upright orientation connecting the flat plate  26  with the base wall  50  of the channel  24 , it may be appreciated that the indication of upper and lower is for illustrative purposes and the carrier  28  may be positioned transversely or in various orientations. Each of the upper arm  44  and lower arm  46  include a hole  52  therethrough. 
     One particularly preferred composition for use as material  30  is commercialized under the name SikaReinforcer (Sika Corporation, Madison Heights, Mich.). In more detail, the most preferred material  30  comprises: from about 20-30% by weight of a styrene-butadiene-styrene (SBS) block co-polymer (e.g., Fina Clear 530®); from about 5-20% by weight of a polystyrene (e.g., Fina Crystal 500® and Fina Crystal 535®); from about 30-45% by weight of a bisphenol A-based liquid epoxy resin (e.g. Araldite 6010® and Epon 71®); from about 0.5-5% by weight of a pigment such as carbon black; up to about 5% by weight butadiene acrylonitrile rubber (Nipol 1411); from about 1-10% by weight hydrated amorphous silica (HiSil 233); from about 10-20% by weight glass microspheres (Scotchlite S60); from about 0.1-5% by weight of a blowing agent such as azodicarbonamide (e.g., Celogen AZ 765®, Celogen AZ 754A®, and Celogen AZ 130®); from about 0.1-5% by weight of a catalyst such as N, N, dimethyl phenyl urea (U405); from about 0.1-5% by weight of a curing agent such as dicyandiamide (DDA10); and up to about 5% by weight of a “kicker” such as zinc oxide to lower the blowing temperature, with all percents by weight being based upon the total weight of the material taken as 100% by weight. 
     A particularly preferred composition of the material  30  comprises about 12.94% polystyrene, about 23.22% SBS block copolymer, about 0.57% carbon black, about 1.90% butadiene acrylonitrile rubber, about 4.28% hydrated amorphous silica, about 38.07% bisphenol A-based liquid epoxy resin, about 14.75% glass microspheres, about 0.46% zinc oxide, about 2.85% dicyandiamide, about 0.38% N,N dimethyl phenyl urea, and about 0.57% azodicarbonamide. In certain applications where increased compressive strength and reduced foaming and expansion is desired, the foregoing may be adjusted such that the polystyrene is reduced to about 12.63%, the SBS block copolymer is reduced to about 22.59%, and the butadiene acrylonitrile rubber is increased to about 2.85%. 
     The material  30  can be formed by mixing the SBS block co-polymer with a small portion (about {fraction (1/40)}th of the total amount) of the bisphenol A-based liquid epoxy resin in a heated mixer until the temperature of the mixer reaches from about 240-260° F. (the temperature of the mixture within the mixer is at least about 175° F.), and the mixture is substantially homogeneous, at which time the polystyrene is added to the mixer and mixing is continued. After the polystyrene is substantially mixed with the SBS block co-polymer/epoxy resin mixture, the remainder of the bisphenol A-based epoxy resin is slowly added to the mixer, stopping and starting the mixer as necessary, with the ingredients being thoroughly mixed to obtain a substantially homogeneous mixture. The desired amount of this mixture is placed in a heated mixer (set at a temperature of about 250° F.) and mixing is commenced. While mixing, the carbon black and rubber are added to the mixer and mixing is stopped once a homogeneous mixture is obtained within the mixer. Either the silica or glass microspheres is added to the mixer, and mixing is resumed and continued until the mixture is homogeneous. This step is repeated, adding the other of the silica or glass microspheres. 
     The temperature of the mixer is then set to a temperature below 160° F., the blowing agent(s), catalyst(s), kicker, and curing agent(s) are added, and mixing is resumed and continued only until the mixture is homogeneous. The resulting mixture is then preferably extruded into strands (at an extruder temperature of 170-180° F. and screw rotation speeds of about 400 rpm) and cut into pellets. The pellets are then injection molded at a temperature of about 180-200° F. using injection molding equipment designed to form the desired shape of the expansible material elements  36  and  38  to be attached to the respective directional foaming shelves  40  and  42 . Each of the reinforcing material elements  36  and  38  are illustrated in the shape of a rectangular block having at least one passage  54  therethrough, the passage including a recess  56 . 
     The directional foaming shelves  40  and  42  may be made of sheet metal such as steel or aluminum, or alternatively of nylon or other synthetic resin material having a melting point higher than the temperature of the bake oven to which the material  30  is subjected. The directional foaming shelves  40  and  42  each include a platform  58  preferably integrally formed with walls  60  and  62  obliquely angled relative thereto. The platform  58  includes at least one aperture  64  positioned in registry with the passage  54  and hole  52 . As illustrated in FIGS. 1 and 3, the walls  60  and  62  may be oriented at right angles to the platform  58  to direct the foamable reinforcing material upward, as shown in FIG. 3. A relieved area  66  may be provided along the remote margin  68  ofthe walls  60  and  62  if localized lateral expansion during foaming is desired. The remote margin  68  may extend higher than the thickness of the reinforcing material to provide room for expansion of the reinforcing material during foaming which might otherwise cause thin-walled structural members to deform. The walls  60  and  62  of a lower directional foaming shelf  42  may thereby support the reinforcing member or, alternatively, the reinforcing member  20  may be coupled to the flat plate  32  by welding, rivets, screws, adhesive or other fasteners and be thereby secured against movement within the cavity  70  of the structural member until activation of the reinforcing material  30 . Each shelf includes at least one, and preferably a plurality of openings  72  therein, whereby upon heating to melt and activate the reinforcing material  30 , the reinforcing material  30  will come into direct contact with the carrier  28  to ensure good bonding between the carrier  28  and the structural member  22 . 
     Fastener  32  may be a nylon push pin  74  as illustrated, or alternatively other fasteners. Nylon push pin  74  is inexpensive, easy to install and provides resilience against impact. 
     In use, the reinforcing member  20  is preferably coupled to the plate  26  by rivets or the like, and then positioned in the cavity  70  of the structural member  22  as the plate  26  is placed in covering relationship to the channel  24 . Upon heating of the structural member in a bake oven to a temperature of at least 300° F., and preferably about 325° F. for a period of about 10 minutes, the reinforcing material will activate, to melt, foam and expand. The directional foaming shelves  40  and  42  cause the reinforcing material elements  36  and  38  to be directed against an opposite location on the structural member and resist lateral flow and expansion of the reinforcing material. By flowing into the openings  72 , the reinforcing material bonds the carrier  28  directly to the structural member  22  without requiring the fastener  32  to bear all of the stress of any force applied therebetween. The resulting reinforced structural member  75  is then allowed to cool to ambient temperature. 
     FIGS. 4 and 5 illustrate a second embodiment of the reinforcing member  20 A which is similar in all respects to that described above, except that instead of extending at right angles to the platform  58 , the walls  60 A and  62 A of directional foaming shelves  40 A and  42 A diverge and are oriented at obtuse angles relative to the platform  58 . As a result, the foamable material  30  of each element  36  and  38  is permitted to engage and bond to a wider area on the opposing surface of the structural member  22  to provide a reinforced structural member  75 A. 
     FIGS. 6 and 7 illustrate a third embodiment of the reinforcing member  20 B, which again is similar in all respects to that described above, except that instead of extending at right angles or obtuse angles to the platform  58 , walls  60 B and  62 B of shelves  40 B and  42 B converge and are oriented at acute angles relative too the platform  58 . As a result, the foamable material  30  of each element  36  and  38  is constrained to engage and bond to a narrower area on the opposing surface of the structural member  22  to provide a reinforced structural member  75 B. Such a narrower engagement area might be desired, for example, where apertures are provided in the structural member which are proximate to one of the reinforcing material elements  36  or  38  but must remain open and unfilled, or where components which are sensitive or must be subsequently removed must be located proximate to the reinforcing member  22  and thus protected from engagement when the reinforcing material foams and expands. 
     FIGS. 8,  9  and  10  illustrate a fourth embodiment of the reinforcing member  20 C, which is similar to that shown in FIGS. 1-3 but wherein two directional foaming shelves  76  are provided on each of the upper arm and lower arm of the carrier  28 , with each of the directional foaming shelves  76  having a platform  78  presenting a plurality of openings  80  and a perimeter wall  82  which surrounds the side margin  84  of the platform  78 . The reinforcing material  30  is provided as discrete reinforcing material elements  86  which are adapted to receive push pins  74  as described above for holding the carrier  28 , shelves  76  and elements  86  together prior to foaming, expansion and bonding to provide a reinforced structural member  88  as shown in FIG.  10 . Use of the directional foaming shelves  76  on the reinforcing member  20 C enables more precise control of the direction of the foaming and bonding of the reinforcing material  30 , and may be especially beneficial when the carrier is bent transversely in a vertical direction to prevent flow of the reinforcing material along an incline, or when longitudinally spaced intervals along the structural member need to remain free of reinforcing material. 
     Although preferred forms of the invention have been described above, it is to be recognized that such disclosure is by way of illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention. 
     The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of their invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set out in the following claims.