Abstract:
A method includes wetting fibers with a resin capable of being cured by at least two different cure treatments. At least partially curing the resin by subjecting the resin to a first cure treatment and at least partially curing the resin by subjecting the resin to a second cure treatment. A plurality of fibers are located adjacent each other so that a plurality of valleys are formed between the plurality of fibers along an outer side of the reinforcement. The resin is cured to retain the valleys in the outer side of the reinforcement. The outer side of the reinforcement is adhered to the structural member. An apparatus including a fiber locating mechanism adapted to retain the peaks and valleys during curing of the resin without rigidly confining the outer side of the reinforcement.

Description:
FIELD OF THE INVENTION 
   The present invention relates to composite fiber and resin reinforcements for structural members; and more particularly, to methods of manufacturing such fiber reinforcements. 
   BACKGROUND OF THE INVENTION 
   Reinforcements for structural members have been manufactured using pultrusion processes. This process generally involves wetting fibers with resin and pulling them through a mold where the resin is cured as a result of heating the resin. The mold tends to create relatively smooth surfaces on the sides of the reinforcement although some recesses are often present. Exemplary pultrusion processes are disclosed, for example, in the following patents: U.S. Pat. No. 3,895,896 which issued to White et al. on Jul. 22, 1975; U.S. Pat. No. 5,286,320 which issued to McGrath et al. on Feb. 15, 1994; U.S. Pat. No. 5,374,385 which issued to Binse et al. on Dec. 20, 1994; U.S. Pat. No. 5,424,388 which issued to Chen et al. on Jun. 13, 1995; U.S. Pat. No. 5,556,496 which issued to Sumerak on Sep. 17, 1996; U.S. Pat. No. 5,741,384 which issued to Pfeiffer et al. on Apr. 21, 1998; and U.S. Pat. No. 5,783,013 which issued to Beckman et al. on Jul. 21, 1998. 
   Another type of pultrusion process has involved spreading resin on a film such as Mylar, adding fiber materials, and then adding a top cover film to form an envelope that essentially becomes a flexible mold. This sandwich is shaped by tension and mechanical forms and is then pulled through an oven to cure the sandwich in the form that is desired. 
   A third variation of pultrusion provides for the fibers to be placed under tension, saturated with photo-initiated resin, pulled through a series of sized dies to form the fibers into a round bundle, and then exposed to high intensity ultraviolet light where curing is initiated. A surface coating is then applied and cured to provide a desired resin rich surface. This process has been used in forming strengthening members of fiber optic cables. Exemplary variations of this process are disclosed in U.S. Pat. No. 4,861,621 which issued to Kanzaki on Aug. 29, 1989; and U.S. Pat. No. 5,700,417 which issued to Fernyhough et al. on Dec. 23, 1997. 
   A forth variation of pultrusion provides for the fibers to be placed under tension, saturated with thermo-reactive resin, pulled through a series of sized dies to form the fibers into a round bundle while exposed to elevated temperatures such as found in an oven. This process has been used in the making of fishing rods and also adapted for fibreoptic cable members. 
   SUMMARY OF THE INVENTION 
   In accordance with one aspect of the present invention method of manufacturing a reinforcement for a structural member includes wetting fibers with a resin capable of being cured by at least two different cure treatments. At least partially curing the resin by subjecting the resin to a first cure treatment and at least partially curing the resin by subjecting the resin to a second cure treatment. 
   In accordance with another aspect of the present invention a method of manufacturing a reinforced structural member comprising a fiber and resin reinforcement and a structural member is provided. The method includes wetting a plurality of fibers with a curable resin. A plurality of fibers are located adjacent each other so that a plurality of valleys are formed between the plurality of fibers along an outer side of the reinforcement. The resin is cured to retain the valleys in the outer side of the reinforcement. The outer side of the reinforcement is adhered to the structural member. 
   In accordance with yet another aspect of the present invention an apparatus for manufacturing a reinforcement for a structural member includes a fiber wetting station adapted to contact a plurality of fibers with a resin. A fiber locating mechanism is adapted to locate the plurality of fibers adjacent each other so that a plurality of valleys are formed between the plurality of fibers along an outer side of the reinforcement and so that a plurality of peaks associated with the fibers are formed. The fiber locating mechanism is further adapted to retain the peaks and valleys during curing of the resin without rigidly confining the outer side of the reinforcement. A resin curing station is adapted to irradiate the outer side of the reinforcement to at least partially cure the resin. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  is a schematic illustration of an apparatus according to the invention for manufacturing a reinforcement for a structural member; 
       FIG. 2  is a schematic illustration of an alternative preferred tensioning mechanism; 
       FIG. 3  is a schematic illustration of an alternative preferred tensioning mechanism; 
       FIG. 4  is a schematic illustration of an alternative preferred tensioning mechanism; 
       FIG. 5  is a schematic illustration of an alternative preferred tensioning mechanism; 
       FIG. 6  is an enlarged fragmentary perspective view of a particularly preferred embodiment of a reinforcement resulting from the method of the present invention; and 
       FIG. 7  is an enlarged cross-sectional view of a preferred reinforced structural member. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
   Referring to  FIG. 1 , a schematic representation of a preferred embodiment of an apparatus of the present invention is illustrated. A plurality of creels  10 ,  11  are provided from which various fibers  12 ,  13  are supplied. The first creel  10  provides a supply of first fibers  12  and the second creel  11  provides a supply of second fibers  13  made from a different material. The creels  10 ,  11  typically include ceramic eyelets  14  through which the fibers  12 ,  13  pass. In addition to the creels  10 ,  11  supplying fibers  12 ,  13 , fibers are provided in the form of a thin veil  16  of non-woven fibers from a supply roll  18 . In this case the non-woven veil  16  is made of a plurality of swirled fibers. Each of the fibers  12 ,  13 ,  16  being supplied to the process are preferably tensioned by tensioning device  20 . In this embodiment, the tensioning device  20  is associated with the creels  10 ,  11  and the supply roll  18 . The tensioning device  20  is provided by brake wheels  20  which resist the unwinding of the various fibers  12 ,  13 ,  16 . It is preferred that the tensioning device  20  be adapted to create substantially the same amount of tension in each of the longitudinal fibers  12 ,  13  of the finished reinforcement. 
   Referring to  FIGS. 2-5 , various alternative preferred tensioning device  20  embodiments are illustrated. These enable the tensioning of the fibers  12 ,  13  to be controlled to adjust the tension of the fibers  12 . These devices may also be used to tension the nylon veil  16 , although for simplicity they are described herein in terms of fibers  12 ,  13 . Referring to  FIG. 2 , the fibers  12 ,  13  pass through a pair of non-aligned ceramic eyelets. A bearing roller  50  and weight ball  52  provide tension in the fiber  12 ,  13  as it is pulled through the eyelets  48 . Referring to  FIG. 3 , a biasing spring  152  pushes against pressure disks  150  to provide a compressive force on the fiber  12 ,  13 . Referring to  FIG. 4 , a rubber belt  252  and brake controlled sheave  250  compress the fiber  12 ,  13  to create tension in the fiber  12 ,  13 . Referring to  FIG. 5 , a pair of ceramic eyelets  48  are moveable on a pivot member  350  to various angles to adjust the amount of tension in the fibers  12 ,  13 . 
   Returning to  FIG. 1 , the fibers  12 ,  13  may be rovings, tows, yarn, other fiber bundles or even individual filaments. In addition, fibers  16  are preferably provided to provide strength in the cross direction through the use of a mat, veil, scrim, tape, woven fibers, sewn fibers, and bonded non-wovens. As described above, this embodiment includes fibers  12  of a first material and fibers  13  of a second material, and a synthetic veil  16 . For this specific preferred embodiment, the first fibers  12  are aramid fibers  13 , the second fibers are fiberglass and the synthetic veil  16  is made of swirled nylon fibers. 
   A broad range of fiber materials may be used. Preferred fibers  12 ,  13 ,  16  are made of materials selected from fiberglass, aramid, carbon, nylon, polyester, polyethylene, ceramic, steel, metal alloys, and boron. The first fibers  12  and the cross-directional fibers  16  which are at the outer sides of the reinforcement are preferably made of synthetic fibers; and more preferably, of aramid, nylon, polyester, and polyethylene. The second fibers  13  which are in the interior of the reinforcement are preferably made of mineral fibers; and more preferably, of fiberglass, carbon and ceramic. 
   The tensioned fibers  12 ,  13 ,  16  are passed through a resin bath  22  of liquid resin  24  to wet the fibers  12 ,  13 ,  16  with the resin  24 . The resin  24  is capable of being cured by at least two different cure treatments. Potential cure treatments include photo-radiation, thermal radiation, electron beam radiation, and radio frequency (e.g., microwave) radiation. More preferably, the resin  24  is a thermosetting resin that is capable of being cured by photo-radiation and thermo-radiation. Examples of preferred resins  24  include polyesters, vinyl esters, epoxy, urethane, and mixtures thereof. More preferred resins  24  are acrylated epoxy and acrylated urethane. 
   The wet fibers  12 ,  13 ,  16  are then subjected to a forming mechanism  26 . The forming mechanism  26  includes doctor blades  28  or other devices to remove excess resin  24  from the fibers  12 ,  13 ,  16 . The forming mechanism  26  helps in appropriately locating the various fibers  12 ,  13 ,  16  relative to each other. In this embodiment, a layer of longitudinally aligned and tensioned first fibers  12  is created adjacent the top outer side. In addition, a central layer is created from longitudinally aligned and tensioned second fibers  13 . Lastly, a layer adjacent the bottom outer side is formed from the resin wetted nylon veil  16 . The fibers  13 ,  12 ,  16  of these three layers are all located adjacent each other with liquid resin material  24  generally filling the space between the fibers  12 ,  13 ,  16 . 
   After passing through the forming mechanism  26  the fibers  12 ,  13 ,  16  can have various tendencies to spring away from each other. This is caused by the apparatus design and/or the fiber materials. In addition, the fiber  12 ,  13 ,  16  to resin  24  ratio is relatively high. Preferably the fiber  12 ,  13 ,  16  to resin  24  ratio is from about 30% to about 70% by volume; more preferably, from about 50% to about 70%; and even more preferably, from about 55% to about 65%. 
   Referring to  FIG. 6 , the upper outer side  30  of the combined liquid resin  24  and fiber  12 ,  13 ,  16  composite has a series of peaks  32  and valleys  34 . The peaks  32  are associated with the outermost fibers  12  which in this embodiment are coated with resin  24 . The valleys  34  are created between at least two outermost fibers  12  causing adjacent peaks  32 . Thus, the peaks  32  and valleys  34  of the top outer side  30  are elongated and oriented longitudinally along the web. Therefore, this outer side  30  has an undulating profile formed by the longitudinally oriented peaks  32  and valleys  34 . 
   Returning to  FIG. 1 , the arranged resin coated fibers  12 ,  13 ,  16  are next subjected to curing while the top outer side  30  has the peaks  32  and valleys  34 . Thus, the undulating surface caused by these peaks  32  and valleys  34  are present in the solid resin  24  and fiber  12 ,  13 ,  16  composite or reinforcement  40  which results from curing. The curing is preferably done while the resin is unconfined by a mold, die or film. In this embodiment, curing is accomplished by subjecting the located, tensioned, fibers  12 ,  13  which have been wetted with liquid resin  24  to ultra-violet (UV) radiation and thermal radiation. Thus, the resin  24  is subjected to two cure treatments. UV lamps  36  provide the source for both the UV radiation and thermal radiation. Since the aramid fibers  12  of this embodiment are not transparent, they create shadows from the UV lamps  36 . The additional use of heat provides for effective curing throughout the resin  24 , even in the UV light shadows within the resin  24 . 
   The heat generated by the UV lamps  36  is sufficient in this embodiment to provide the necessary thermal radiation. Alternatively, additional heat sources are included. The combination of the UV radiation and heat from the lamps  36  is sufficient to fully catalyze the resin. These additional heat sources are preferably selected from infrared heaters, radio frequency (e.g., microwave) heaters, or other devices to provide thermal radiation or convection. Preferably, the resin  24  has a catalyzation that is thermo reactive at a temperature which is at least about 200° F.; more preferably at least about 250° F.; and even more preferably, at least about 275° F. Such preferred catalyzation temperatures provides a more stable resin system at room temperature or at somewhat elevated temperatures. Since the resin viscosity is dependant on the temperature, this will allow for slightly elevated resin temperature to be used to attain the most suitable viscosity for processing. 
   Pairs of wheels  38  operate as puller clamps to pull the cured composite  40  out of the curing station. Alternative puller clamps may include caterpillar treads or another clamp and pull source. In this embodiment, the wheels  38  are driven by a drive mechanism (not seen). The wheel pairs  38  provide the force which works in combination with the tensioning device  20  to cause tension on the fibers  12 ,  13 ,  16  throughout the curing process. Thus, the fibers  12 ,  13  of this embodiment are in longitudinal tension while the resin is cured. The puller clamps  38  feed the cured composite  40  to a roll-up station for storing and subsequent processing plain text. Alternatively, the cured reinforcement is delivered to a cutting station which cuts the reinforcements into desired sizes and shapes. 
   Referring to  FIG. 7 , a preferred embodiment of a reinforcement  40  according to the present invention is illustrated. The reinforcement  40  which results from the above is preferably subsequently adhered to a structural member  44 . The adhesive  46  flows into the valleys  34  of the reinforcement  40  and bonds to the valleys  34 . In addition, the reinforcement  40  is preferably adapted to permit the adhesive  46  to penetrate completely through the overall thickness of the reinforcement  40 . Thus, the resin  24  may include pores or cracks in the resin  24  may be encouraged or permitted, for example, by bending the reinforcement  40 . 
   By bonding to the valleys  34  and/or penetrating completely through the overall thickness of the reinforcement  40  the adhesive  46  creates a particularly strong mechanical bond between the reinforcement  40  and the wood structural member  44 . The adhesive  46  may be any type of adhesive suitable for attaching the reinforcement  40  to the structural member  44 . 
   Many modifications can be made to the above described embodiments. For example, in one alternative the resin may be poured over the already located and tensioned fibers. In another alternative, the fibers may be placed on top of a pool of resin. As another alternative, a veil might be placed on the top side to create the peaks and valleys in association with the swirled fibers of the veil. Thus, the peaks and valleys would not have such a highly elongated shape as that illustrated above. As yet another alternative, the various fibers may be mixed together rather than oriented in layers. 
   The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.