Patent Publication Number: US-2005142333-A1

Title: Method of manufacturing composite vehicle panels

Description:
BACKGROUND OF THE INVENTION  
      The invention relates generally to a method for manufacturing a vehicle panel and more particularly to a method of fabricating and assembling composite panels for use on motor vehicles such as pickup trucks, crossover vehicles 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 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 is disposed upon and engages the rails of the truck bed.  
      There the simplicity ends because this seemingly simple 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 wall rail of the truck bed or by including 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 be amenable to being 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, frequently four feet by six feet and sometimes larger, it is desirable that they exhibit reduced weight in order to not adversely impact the gas mileage obtained by 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, lower panel with a plurality of raised features having coplanar end portions, forming a second, upper panel having a depending peripheral lip adapted to engage a periphery of the first panel, placing an adhesive on the end portions of the raised features of the first panel and securing said panels together at the raised features and about the peripheral lip.  
      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 with a plurality of raised features 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 around their periphery.  
      It is a still further object of the present invention to provide a composite vehicle panel wherein features projecting from a lower panel take the form of cone frustums, elongate ribs or channels and the like.  
      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 and disposed over the bed of a pickup truck;  
       FIG. 2  is an enlarged, fragmentary view in partial section of a composite vehicle panel according to the present invention utilized as a tonneau cover, taken along like  2 - 2  of  FIG. 1 ;  
       FIG. 3  is an enlarged, fragmentary, sectional view of upper and lower mold segments which illustrates production of a first or lower panel according to the present invention;  
       FIG. 4  is a perspective view of an adhesive applying step of the method of fabricating a composite panel according to the present invention;  
       FIG. 5  is an enlarged, fragmentary, sectional view of upper and lower mold segments which illustrates production of a second upper panel according to the present invention;  
       FIG. 6  is a fragmentary, sectional view of a mold for undertaking the assembly step of a method of fabricating composite vehicle panels according to the present invention;  
       FIG. 7  is an enlarged fragmentary view in partial section of a first alternate embodiment of a composite vehicle panel according to the present invention utilized as a tonneau cover;  
       FIG. 8  is a perspective view of an adhesive applying step according to the method of fabricating composite vehicle panels according to the present invention;  
       FIG. 9  is a fragmentary, sectional view illustrating the assembly of the upper and lower panels of a first alternate embodiment composite vehicle panel according to the present invention;  
       FIG. 10  presents a final fabrication step of a first alternate embodiment composite vehicle panel according to the present invention;  
       FIG. 11  is an enlarged fragmentary view in partial cross section of a second alternate embodiment of a composite vehicle panel according to the present invention utilized as a tonneau cover;  
       FIG. 12  is a perspective view of a second alternate embodiment first or lower panel for a composite vehicle panel according to the present invention; and  
       FIG. 13  is an enlarged, fragmentary sectional view of a portion of the first, lower panel of a composite vehicle panel taken along line  13 - 13  of  FIG. 12 .  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED AND ALTERNATE EMBODIMENTS  
      Referring now to  FIG. 1 , a composite vehicle panel is illustrated and generally designated by the reference number  10 . The composite vehicle panel  10  illustrated 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 . The composite panel  10  is fitted over the open top of a truck bed  14  having a pair of opposed, spaced apart conventional sidewalls  16  which 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, SUV&#39;s and crossover vehicles having an exterior cargo bed.  
      Referring now to  FIG. 2 , the composite vehicle panel  10  includes a first or lower panel  30  having a plurality of spaced apart upwardly extending features or projections  32  which may define frusto-conical shapes or other polygonal tapering shapes having flat, coplanar upper surfaces  34 . Generally adjacent the periphery of the first or lower panel  30  are elongate, shallower features or projections  36  having upper planar surfaces  38  which are at a reduced height relative to the surfaces  34 . The features or projections  36  are preferably rectangular and disposed generally parallel to and proximate an edge of the lower panel  30 . The elongate features or projections  36  may include right angle features  36 A adjacent the corners of the panel  30 . The tapering walls of the features or projections  32  and  36  are configured primarily to assist removal of the lower panel  30  from molding equipment and, as such, may exhibit a draft of 5° to 10° or more or less if desired. The first or lower panel  30  also includes a downturned or depending peripheral edge or lip  42 .  
      The composite vehicle panel  10  also includes second or upper panel  44  which is preferably a planar region  46  and includes a peripheral downturned edge or lip  48  having inside dimensions, i.e., length, width and radiused corners, equal to the outside dimensions adjacent the lip  42  of the second or lower panel  30  such that the first or lower panel  30  may fit snugly and without strain into the second or upper panel  44 , as illustrated in  FIG. 2 .  
      Turning now to  FIGS. 3, 4  and  5 , the steps of manufacturing and assembling the composite vehicle panel  10  will now be described. Turning first to  FIG. 3 , a conventional thermoforming mold having a first or lower male mold segment  52  and, optionally, a second or upper matching female mold segment  54  are utilized. Whether the second or upper matching female mold segment  54  is utilized or the lower panel  30  is vacuum formed only against 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 lower panel  30 . The lower male mold segment  52  preferably includes a plurality of vacuum passageways  56  which communicate from the surface of the mold segment  52  to a plenum  58  which is defined by a plenum wall  62  on the back side of the male mold segment  52 . A vacuum pump  64  draws a partial vacuum in the plenum  58  such that air is drawn through the passageways  56  in accordance with conventional practice.  
      A sheet of thermoformable material  66  is placed between the mold segments  52  and  54 , the vacuum pump  64  is activated and the mold segments  52  and  54  are drawn together, forming the sheet of thermoformable material  66  into the first or lower panel  30  illustrated in  FIGS. 2 and 4 . The thermoformable material  66  may be high density polyethylene (HDPE), thermoplastic polyolefin (TPO) or one of several other similar thermoplastic materials such as acrylonitrile-butadiene-styrene (ABS). Subsequent to molding, the mold segments  52  and  54  are separated and the formed lower panel  30  is removed.  
      Turning now to  FIG. 4 , the thermoformed first or lower panel  30  is then positioned with the coplanar surfaces  34  up such that adhesive  68  may be applied thereto. Preferably, adhesive  68  is applied through the agency of a movable roller assembly  72 . A freely rotatable, horizontally disposed elongate roller  74  is provided with the adhesive  68  through a horizontal elongate nozzle  76  which is preferably disposed above and proximate the roller  74 . The elongate nozzle  76  may be supplied with liquid adhesive through a tube or pipe  78  from a suitably disposed pump  82 . The roller assembly  72  is preferably suspended upon a pair of spaced apart, parallel tracks  84  which maintain the roller  74  at an appropriate vertical location such that the roller  74  contacts the coplanar surfaces  34  and applies adhesive thereto as it is translated over the panel  30 . The roller assembly  74  may be translated manually or may be coupled to a suitable bi-directional, semi-automatic or automatic drive system (not illustrated).  
      Referring now to  FIG. 5 , the second or upper panel  46  is formed in a mold assembly having a first or lower mold assembly  88  having vacuum passageways  90  and a second optional upper mold assembly  92 . The mold cavity which is occupied by a sheet of thermoplastic material  94  is molded into the second or upper panel  44  which is primarily planar but includes a depending peripheral lip  48  all of which is formed in the proper size by the mating mold segments  88  and  92 . Subsequent to molding the panel  44 , the mold segments  88  and  92  are separated and the second or upper panel  44  is removed therefrom.  
      Referring now to  FIG. 6 , the first or lower panel  30  having adhesive  68  applied to the surfaces  34  and the second or upper panel  44  are secured together. The panels  30  and  44  are disposed in a first or lower mold segment  96  and a second or upper mold segment  98  which defines a mold cavity  100  having a narrow peripheral margin  102  which receives the lips or flanges  42  and  48  of the panels  30  and  44 . The spacing between the upper surface of the lower mold segment  96  and the lower surface of the upper mold segment  98  is such that closure of the mold segments  96  and  98  compresses the first and second panels  30  and  44  such that the adhesive  68  bonds the two panels together at the points of contact of the upper portions  34  of the features or projections  32  and about the periphery of the panels at the lips or flanges  42  and  48 .  
      Referring now to  FIG. 7 , a first alternate embodiment of a composite vehicle panel utilized as a tonneau cover is illustrated and generally designated by the reference number  110 . The first alternate embodiment composite vehicle panel  110  includes a first or lower panel  112  having a plurality of reduced height, elongated, rectangular features or projections  114  which are parallel to and extend about the periphery of the panel  112 . Extending across the center region of the panel  112  or a plurality of spaced apart convolutions or corrugations  116  which are disposed in parallel and extend from proximate the rectangular features or projections  114  along one edge of the panel  112  to similar features or projections  114  extending along the opposite edge of the panel  112 . The convolutions or corrugations  116  are taller than the rectangular features or projections  114  having highest or uppermost parallel regions  118 . The first or lower panel  112  also includes a peripheral depending flange or lip  120  which extends fully about its periphery. The first alternate embodiment composite panel 110  also includes a second or upper panel  122  having a planar central region  124  or depending flange or lip  126  extending fully about its periphery. Once again, the inside dimensions of the second or upper panel  122  adjacent the edge of the depending flange or lip  126  are equal to the outside dimensions of the first or lower panel  112  at its depending flange or lip  120 .  
      As illustrated in  FIG. 8 , production of the first or lower panel  112  and of the second or upper panel  122  is essentially the same as production of the panels  30  and  46  of the preferred embodiment panel  10  and will therefore not be repeated reference to paragraphs  29  through  32  above, being encouraged. Application of adhesive  68  to the first or lower panel  112  and specifically to the uppermost regions  118  of the projecting convolutions  116  may be achieved by the adhesive applying step illustrated in  FIG. 4 . Alternatively, however, adhesive  68  may be applied directly to the top portions  118  of the convolutions or corrugations 116  by an elongate, adhesive distributing horizontal header  128  having a plurality of nozzles  132  spaced apart at distances equal to the spacing of the corrugations  116 . The horizontal header  128  also includes a nozzle  134  which applies adhesive  68  to the depending lip  120 . The elongate header  128  is provided with adhesive through a flexible hose  136  from a pump  138 .  
      Referring now to  FIGS. 9 and 10 , subsequent to application of the adhesive  68  to the top portions  118  of the convolutions or corrugations  116  and the exterior of the depending lip  120 , the first or lower panel  112  and the second or upper panel  122  are placed within mating mold segments. The first or lower panel  112  is disposed upon a male mold segment  140  and the second or upper panel  122  is disposed upon the first or lower panel  112  or retained by a partial vacuum drawn through passageways  142  on a female or upper mold segment  144 . As illustrated in  FIG. 9 , the mold segments  140  and  144  are brought together to define a mold cavity  146  having a height which suitably compresses the adhesive  68  and intimately bonds the first or lower panel  112  to the second or upper panel  122 . The mold segments  140  and  144  are then separated and the first alternate embodiment composite panel  110  may be removed therefrom.  
      Referring now to  FIGS. 11, 12  and  13 , a second alternate embodiment composite panel  150  which may be utilized as a tonneau cover or similar product is illustrated. The second alternate embodiment composite panel  150  includes a first or lower panel  152  having a generally X-shaped configuration of convolutions which provide strengthening and improve the rigidity of the composite panel  150 . The first or lower panel  152  includes four triangular reinforcing ribs  154  which define an X with closed ends when viewed in plan. Each of the reinforcing ribs  154  is arranged with one side parallel to a peripheral edge of the panel  152  and with four points meeting in the center of the lower panel  152 . As illustrated in  FIG. 13 , convolutions of adjacent reinforcing ribs  154  define a double convolution which produces the X pattern noted above. The top portions  156  of the ribs  154 , like the projections in the other embodiments, receive adhesive  68 . The first or lower panel  152  also includes a peripheral depending flange or lip  158 . Adhesive  68  on the flange or lip  158  and, with the adhesive  68  on the reinforcing ribs  154 , secures the first or lower panel  152  to a second or upper panel  160 . The second or upper panel  160  also includes a downturned or depending peripheral flange or lip  162 . The second alternate embodiment composite panel  150  also includes a U-shaped elastomeric gasket or channel  164  which acts as a cosmetic closure, a bumper and a weatherstrip. It will be appreciated that the first or lower panel  152  and the second or upper panel  160  may be made of HDPE or similar rugged and dimensionally stable thermoplastic according to the process steps described above.  
      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 truck beds, bed liners and manufacturing processes therefor. 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.