Abstract:
A method of fabricating composite vehicle panels includes the steps of forming a first, upper panel having a depending peripheral lip, forming a second, lower panel of laid up woven mat or strips of a fibrous material such as fiberglass or carbon fibers and a plastic resin to form a corrugated panel having a depending peripheral lip, placing an adhesive on the raised portions of the corrugations and the peripheral lip of the second panel and securing the panels together at the corrugations and about their peripheral lips.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates generally to a method for manufacturing a composite panel and more particularly to a method of fabricating and assembling composite panels for use on motor vehicles such as pickup trucks, crossover vehicles, SUV&#39;s and the like. 
     The continuing popularity of pickup trucks and crossover vehicles having a passenger compartment smaller than an SUV but also including a truck bed has created a growing market for accessories for these vehicles. One of the most popular accessories is a closure or tonneau cover for the truck bed. Characterized most simply, the tonneau cover is a horizontally disposed structure which covers the truck bed and engages and is supported by the rails of the truck bed. 
     There the simplicity ends because this seemingly utilitarian device is subject to many structural and operational requirements. First of all, the closure or tonneau cover must generally not be stationary but must be movable to permit access to the truck or bed by being hinged along its juncture with the front rail of the truck bed or by including center hinges pivoting along the longitudinal axis of the truck bed to provide access into the truck bed from either the left side of the truck, the right side of the truck or both. Given the likelihood of hauling valuable cargo in the truck bed, the tonneau cover must also include a locking feature in order to be locked to provide a reasonable degree of security. 
     Structurally, the cover must be strong and dimensionally stable. Since the cover will be subjected to typical ambient extremes of temperature as well as heating from the sun and weight from heavy snow or an object placed thereupon, it must exhibit exceptional strength and ruggedness. 
     Cosmetically, the product is demanding as well since the product finish must accept paint and result in a surface appearance rivaling that of painted sheet metal in order to be acceptable to purchasers. 
     Last of all, given the size of such tonneau covers, typically four feet by six feet (1.22 m by 1.83 m) and frequently larger, it is necessary that the issue of total weight be considered and addressed in order to not adversely impact the overall vehicle weight and fuel economy of the vehicle. 
     All of the foregoing requirements are addressed by the method and resulting product described more fully below. 
     SUMMARY OF THE INVENTION 
     A method of fabricating composite vehicle panels includes the steps of forming a first, upper panel having a depending peripheral lip, forming a second, lower panel of a laid up woven mat or strips of a fibrous material such as fiberglass or carbon fibers and a plastic resin to form a corrugated panel having a depending peripheral lip, placing an adhesive on the raised portions of the corrugations and the peripheral lip of the second panel and securing the panels together at the corrugations and about their peripheral lips. An elastomeric channel may be disposed over the adjacent ends of the lips and functions as a bumper and weather strip. The product produced by this method is also disclosed and claimed. 
     Thus it is an object of the present invention to provide a method of fabricating composite vehicle panels. 
     It is a further object of the present invention to provide a method of fabricating composite vehicle panels having a lower panel including a plurality of corrugations which are secured by an adhesive to an upper panel. 
     It is a still further object of the present invention to provide a method of fabricating composite vehicle panels which are secured together about their peripheries. 
     It is a still further object of the present invention to provide a product manufactured in accordance with the disclosed process. 
     Further objects and advantages of the present invention will become apparent by reference to the following description of the preferred embodiment and appended drawings wherein like reference numbers refer to the same component, element, or feature. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a composite panel according to the present invention utilized as a tonneau cover for the bed of a pickup truck; 
         FIG. 2  is an enlarged, fragmentary, sectional view of a composite panel according to the present invention utilized as a tonneau cover, taken along line  2 — 2  of  FIG. 1 ; 
         FIG. 3  is an enlarged, fragmentary, sectional view of upper and lower mold segments illustrating the production of a first or upper panel according to the present invention; 
         FIG. 4  is an enlarged, fragmentary, sectional view illustrating the application of plastic resin or binders to fibers or a fibrous mat to produce a second or lower panel according to the present invention; 
         FIG. 5  is an enlarged, fragmentary sectional view illustrating the application of adhesive to the second or lower panel according to the present invention; 
         FIG. 6  is an enlarged, fragmentary, sectional view of two mold segments illustrating the final fabrication step of a composite vehicle panel according to the present invention; and 
         FIG. 7  is an enlarged, fragmentary, sectional view of a completed composite vehicle panel according to the present invention in a mold assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to  FIGS. 1 and 2 , a composite vehicle panel is illustrated and generally designated by the reference number  10 . The composite vehicle panel  10  is generally referred to as a tonneau cover but may be one of several different vehicular panels such as a floorboard, a door panel, a roof panel or other generally planar body panel for use on or with a motor vehicle such as a pickup truck  12 . If a tonneau cover, the composite panel  10  is fitted over the open top of a truck bed  14  having a pair of opposed, spaced apart sidewalls  16  defining horizontal, longitudinally extending rails  18 . The sidewalls  16  are connected by a front wall (not illustrated) and a horizontal bottom panel (also not illustrated). The pickup truck  12  also includes a tailgate assembly  20  and a cab  22 . It will be appreciated that the pickup truck  12  illustrated is conventional and representative of a broad range of pickup trucks and crossover and other vehicles having an exterior cargo bed. 
     Referring now to  FIG. 2 , the composite vehicle panel  10  includes a first or upper panel  30  having a central planar surface  32  and a peripheral depending flange or lip  34  which extends about the periphery of the central planar surface  32  and downwardly therefrom. The composite vehicle panel  10  also includes a second or lower panel  40  which defines a plurality of elongate ribs or corrugations  42  having raised elongate surfaces  44  and a depending peripheral flange or lip  46  which extends about the entire periphery of the panel  40 . The inside dimensions of the first or upper panel  30  adjacent the terminal portion of the peripheral edge or lip  34 , i.e., the length, width and radiused corners are preferably equal to the outside dimensions adjacent the terminal portion of the peripheral lip  46  of the second panel  40 . A bead of adhesive  48  resides between and secures the raised elongate surfaces  44  of the elongate corrugations  42  as well as the inner surface of the peripheral lip  34  and the outer surface of the peripheral lip  46  to one another as illustrated. Preferably, a U-shaped elastomeric channel  50  is disposed over the adjacent edges of the lips  34  and  46 . Both an interference fit and the adhesive  48  retain the U-shaped channel  50  on the lips  34  and  46 . The U-shaped channel  50  functions as a cosmetic feature, a bumper to cushion contact with the rails  18  of the truck bed  14 , and as a weather seal between the tonneau cover  10  and the rails  18 . 
     Turning now to  FIGS. 3 ,  4 ,  5 ,  6  and  7 , the steps of fabricating and assembling the composite vehicle panel  10  will now be described. Turning first to  FIG. 3 , a conventional thermoforming die having a first or lower female mold segment  52  and, optionally, a second or upper matching male mold segment  54  are utilized. Whether the second or upper matching mold segment  54  is utilized or the upper panel  30  is vacuum formed against only the first or lower mold segment  52  is determined by the characteristics of the material being formed and the desired amount of detail on the panel  30 . The lower female mold segment  52  preferably includes a plurality of vacuum passageways  56  which communicate from the mold surface of the mold segment  52  to a plenum  58  which is defined by a plenum wall  60  on the back side of the female mold segment  52 . A vacuum pump  62  draws a partial vacuum in the plenum  58  such that air is drawn through the passageways  56  and the panel  30  is drawn into intimate contact with the surface of the female mold segment  52 . Assisting such accurate thermoforming is the optional male mold segment  54  which is moved into intimate contact with the face of the panel  30  opposite the female mold segment  52 . When the panel  30  has sufficiently cooled, the mold segments  52  and  54  are moved apart and the panel  30  is removed. The panel  30  may be high density polyethylene (HDPE), thermoplastic olefin (TPO) or other suitably rugged and dimensionally stable thermoplastic material. It should be understood that the panel must be at an elevated temperature of several hundred degrees Fahrenheit before being placed in the mold segments  52  and  54 . This may be achieved by utilizing the material promptly after it was extruded from a production extrusion machine (not illustrated) or reheating the panel  30  if it is at ambient temperature because it has been allowed to cool after its extrusion. 
     Referring now to  FIG. 4 , the second or lower panel  40  is fabricated in a female mold or die  66  having a mold cavity surface  68  corresponding to the desired shape and configuration of the second or lower panel  40 . As such, the female die  66  defines a plurality of elongate, parallel corrugations  72  and an oblique wall  74 . A fibrous layer, strips, or a mat  78  of, for example, fiberglass or random strands of fiberglass, carbon fiber or other stable, fibrous reinforcing material is placed upon the mold surfaces  72  and  74 . A single or multiple component spray head  80  is then translated over the surface of the female die  66 , either manually or through the agency of a mechanical or robot arm (not illustrated) to apply suitable plastic or resin binder  82  to the fibrous layer or mat  78 . If desired, multiple layers of fibers  78  and of plastic or resin binder  82  may be laid upon the female die  66 . After an appropriate time, the second or lower panel  40  may be removed from the female die  66  and after suitable drying or curing, the second or lower panel  40  is ready for assembly. 
     Referring now to  FIG. 5 , the adhesive  48  is preferably applied directly to the raised elongate surfaces  44  of the corrugations  42  by an elongate, horizontal adhesive distributing header  86  having a plurality of nozzles  88  spaced apart at distances equal to the spacing of the convolutions  42 . The horizontal header  86  also includes a nozzle  92  which applies the adhesive  48  to the depending lip  46 . The elongate header  86  is provided with the adhesive  48  through a flexible hose  94  from a suitable pump  96  and bulk source (not illustrated). 
     Referring to  FIGS. 6 and 7 , subsequent to application of the adhesive  48  to the raised elongate surfaces  44  of the convolutions  42  and the exterior of the depending lip  46 , the first or upper panel  30  and the second or lower panel  40  are placed within mating mold segments. The first or upper panel  30  is disposed within a female mold segment  102  and the second or lower panel  40  is disposed upon a male mold segment  106 . The first or upper panel  30  may be retained in the first mold segment  102  by a partial vacuum provided through passageways  104  in accordance with conventional practice. As illustrated in  FIG. 7 , the mold segments  102  and  106  are brought together and define a mold cavity  108  having a height which engages the panels  30  and  40  and suitably compresses the adhesive  48  and intimately bonds the first or upper panel  30  to the second or lower panel  40 . The mold segments  102  and  106  are then separated and the composite vehicle panel  10  is removed therefrom. Preferably, before the adhesive  48  has hardened, the U-shaped channel  50  illustrated in  FIG. 2 , is installed over the adjacent ends of the flanges or lips  34  and  46 . 
     The foregoing disclosure is the best mode devised by the inventors for practicing this invention. It is apparent, however, that products and methods incorporating modifications and variations will be obvious to one skilled in the art of composite panels, tonneau covers and manufacturing processes therefore. Inasmuch as the foregoing disclosure presents the best mode contemplated by the inventor for carrying out the invention and is intended to enable any person skilled in the pertinent art to practice this invention, it should not be construed to be limited thereby but should be construed to include such aforementioned obvious variations and be limited only by the spirit and scope of the following claims.