Abstract:
A closure panel including an outer shell for closing an opening defined by a vehicle body and an inner reinforcement. The outer shell and inner reinforcement are formed as a plurality of additive layers. The inner reinforcement includes an integral thickened edge formed around the periphery of the outer shell, an integral latch buttress provided on a first side of the inner reinforcement and a pair of integral hinge buttresses provided on a second side of the inner reinforcement. Internally threaded protrusions may be formed as additive deposits on the integral buttresses.

Description:
TECHNICAL FIELD 
     This disclosure relates to a one piece closure member formed by a plurality of additive layers. 
     BACKGROUND 
     A conventional vehicle closure assembly, such as a hood assembly, generally consists of a stamped sheet metal hood outer, a stamped hood inner, hood latch, hinge reinforcements, and other reinforcements as needed for strength and stability required for the functionality of the hood assembly. Reinforcements are secured to the hood inner by welding, structural adhesives, threaded fasteners, rivets or similar joining techniques to assemble a hood inner sub-assembly. The hood inner sub-assembly may be joined at the periphery with the hood outer using structural adhesives and a hem flanging process. The large number of component parts assembled together to make a vehicle closure member adds to the cost and complexity of the manufacturing process. The components of a hood assembly may be made from SMC, carbon fiber, steel, aluminum or other metals resulting in problems assembling parts made of dissimilar materials. 
     Additive manufacturing processes, commonly referred to as 3D printing processes, are used to form objects by sequentially depositing material with a printer and subsequently hardening the deposited material to complete the part manufacturing process. A powder form metal or polymer material and binder may be deposited by a printer head on a 3-D printing machine bed that is later melted to soften the material and then solidified by applying heat or light. Different methods of solidifying the printed layers include selective laser melting (SLM), direct metal laser sintering (DMLS), selective laser sintering (SLS), fused deposition modeling (FDM), fused filament fabrication (FFF), stereo lithography (SLA), and laminated object manufacturing (LOM). Another approach is to extrude thin layers of molten material with an extruder that is later solidified. 
     Additive manufacturing processes utilize computer aided design (CAD) data or data from another electronic data source to produce 3D objects. The CAD is provided to a 3D printer to produce objects directly from the CAD data. 
     Prototype automotive parts have been made with additive processes but the time required to produce parts in high volumes has prevented the adoption of additive processes for manufacturing. Potential advantages of adopting additive manufacturing processes include eliminating the need to develop stamping die sets and welding or joining robots and tools to join multiple parts of an assembly together. 
     The above problems and other problems are addressed by this disclosure as summarized below. 
     SUMMARY 
     According to one aspect of this disclosure, a one piece closure panel is provided for a vehicle. The closure panel includes an outer shell forming part of an outer surface of a vehicle and an inner portion. The inner portion includes a thickened, radiused edge that extends around a periphery of the outer shell on an inner surface of the outer shell. The inner portion includes a latch buttress formed on the inner surface of the outer shell. The inner portion also includes first and second hinge buttresses formed on the inner surface of the outer shell. 
     The thickened edge may define a slot-shaped void between the inner portion and the outer shell that extends around the periphery of the outer shell and is open toward the interior of the panel. 
     The latch buttress may be an additive deposit on a front portion of the closure panel. The first and second hinge buttresses may be additive deposits on a rear portion of the closure panel. The outer shell, the peripheral thickened edge, the latch mounting portion and the first and second hinge mounting portions may all be part of a unitary one-piece structure. 
     The latch buttress may further comprise an internally threaded protrusion extending from an internal surface of the front portion toward the outer panel. The latch buttress may define a space between the latch buttress and the outer panel. 
     The hinge buttress may further comprise an internally threaded protrusion extending from an internal surface of the rear portion toward the outer panel. The hinge buttress may define a space between the hinge buttress and the outer panel. 
     The closure panel may further comprise an edge facing outwardly from the periphery of the outer shell. The edge is outboard of the outer shell and the inner portion. The edge may be a radiused wall extending around the periphery of the closure panel. 
     According to another aspect of this disclosure, the outer shell may be formed by a first plurality of additive deposited layers having a thickness T 1 . The inner portion, thickened edge, latch buttress and the first and second hinge buttresses may be formed by a second plurality of additive deposited layers having a thickness T 2  that is thicker than T 1 . 
     The closure panel may further comprise an interstitial energy absorbing element disposed between the outer shell and the inner portion at a location where the outer shell and the inner portion define a cavity. The interstitial energy absorbing element may be a resilient wall extending from the outer shell to the inner portion. The wall may include a plurality of discrete wall portions that are connected at an angle to adjacent wall portions. The interstitial energy absorbing portion may comprise a plurality of integrally formed additive deposited layers that exert a spring force on the outer shell and the inner portion. 
     According to another aspect of this disclosure, a closure panel is disclosed that includes an outer shell for closing an opening defined by a vehicle and an inner reinforcement. The outer shell and inner reinforcement are formed as a plurality of additive layers. The inner reinforcement includes a radiused styling edge formed around the periphery of the outer shell, a latch buttress provided on a first side of the inner reinforcement and a pair of hinge buttresses provided on a second side of the inner reinforcement. 
     The closure panel may further comprise an interstitial energy absorbing element including a plurality of discrete wall portions that are connected at an angle to adjacent wall portions to form a living hinge. 
     The above aspects of this disclosure and other aspects are described below with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a vehicle. 
         FIG. 2  is an exploded perspective view of a prior art vehicle closure panel. 
         FIG. 3  is a prior art cross-sectional view of a closure panel including a hood latch reinforcement. 
         FIG. 4  is a fragmentary cross-sectional view of the prior art closure panel showing a hem flange. 
         FIG. 5  is a prior art fragmentary cross-sectional view of a closure panel showing a hinge reinforcement plate. 
         FIG. 6  is a top plan view of a one-piece closure panel. 
         FIG. 7  is a bottom plan view of a one-piece closure panel. 
         FIG. 8  is a cross-sectional view of the one-piece closure panel showing a latch buttress. 
         FIG. 9  is a fragmentary cross-sectional view showing one embodiment of a thickened, radiused edge taken in the circle in  FIG. 8 . 
         FIG. 10  is a fragmentary cross-sectional view of another embodiment of the thickened, radiused edge of the closure panel. 
         FIG. 11  is a cross-sectional view of the one-piece closure panel showing a hinge buttress portion. 
     
    
    
     DETAILED DESCRIPTION 
     The illustrated embodiments are disclosed with reference to the drawings. However, it is to be understood that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed are not to be interpreted as limiting, but as a representative basis for teaching one skilled in the art how to practice the disclosed concepts. 
     Referring to  FIG. 1 , a vehicle  10  is illustrated that includes several closure panels  12 . One closure panel illustrated is a hood  12 A. Alternatively, the closure panel  12  may be a door  12 B or a deck lid  12 C. The scope of this disclosure should be interpreted to include a vehicle having a one-piece closure panel that may be either a hood  12 A, a door  12 B, or deck lid  12 C. 
     Referring to  FIG. 2 , a prior art hood  12 A is illustrated in an exploded perspective view. The hood  12 A includes an outer panel  16  that is joined to an inner panel  18 . A deposit of adhesive  20  is illustrated that is applied to either the outer panel  16  or inner panel  18  about the perimeter of the closure panel  12 . A latch mounting plate  22  is assembled to the inner panel  18 . A pair of hinge mounting plates  24  is assembled to the inner panel  18 . A latch (not shown) is adapted to be secured to the latch mounting plate  24 . A pair of hinges (not shown) is adapted to be attached to the hinge mounting plates  24 . 
     Referring to  FIGS. 3 and 4 , a prior art hood  12 A is partially illustrated in cross section. The hood  12 A includes the outer panel  16  and inner panel  18  that are joined together at a hem flange  26 . A latch mounting plate  22  is attached to the inner panel  18  by welding or by fasteners. The latch mounting plate  22  is adapted to receive a hood latch and may include a striker rod that may be attached to or formed as part of the latch mounting plate  22 . In  FIG. 4 , a prior art outer panel  16  is formed into the hem flange  26  and encloses an internal flange  28  and adhesive  20 . The internal flange  28  is part of the inner panel  18 . The hem flange  26  and adhesive  20  are used to securely attach the inner panel  18  to the outer panel  16 . 
     Referring to  FIG. 5 , a fragmentary cross-sectional view of a prior art hood  12 A is provided that illustrates how the outer panel  16  is attached to the inner panel  18  with a hinge mounting plate  24 . The hinge mounting plate  24  is assembled by using fasteners, welding or adhesive to the inner panel  18 . The outer panel  16  is connected by a hem flange  26  to the inner panel  18 . 
     Referring to  FIG. 6 , a one-piece closure panel  30  is illustrated that includes an outer skin  32 . The outer skin  32  may be formed with finer metal powder (e.g., 0.7 mils) or laid down in a thinner layer to improve the surface finish of the outer skin  32 . The inner portion  34  is not a Class-A surface and may be made in thicker layers or with larger powder particles (e.g., 2.5 mils). For example, the layers forming the outer skin  32  may have a thickness T 1  of 0.01 mm and the inner portion  34  may have a thickness T 2  of 0.05 mm. The outer skin  32  printed using smaller particles accumulates in thinner layers. The inner portion  34  may be formed of thicker particles that are applied in thicker layers. By providing a thinner layer, it is believed that the outer skin  32  of the one-piece closure panel  30  may be solidified into a smoother surface. 
     Different nozzles may be used to facilitate different application rates or to save time during the manufacturing process. Alternatively, one nozzle may be used to form both the outer skin  32  and the inner portion  34 . 
     Referring to  FIG. 7 , the one-piece closure panel  30  is shown inverted to illustrate the structure of the inner portion  34  of the one-piece closure panel  30 . 
     Referring to  FIG. 8 , the one-piece closure panel  30  is shown with the outer skin  32  attached to the inner portion  34  at a thickened edge  36 . The thickened edge  36  may have a radius of about 2.5 mm. The hollow edge  40  including the slot-shaped void  42  is intended of be of lighter weight, but may also provide a 2.5 mm radius styling edge. 
     A latch buttress  46  is formed on the inner portion  34 . The inner portion  34  and latch buttress  46  define striker rod holes  48  that are adapted to receive a striker rod of the hood latch mechanism. The inner portion  34  and latch buttress  46  also define a striker rod access hole  50  that are adapted to receive a hood latch that is accessible through the striker rod access hole  50 . 
     Referring to  FIG. 9 , one embodiment of the thickened edge  36  is shown. The thickened edge  36  shown in  FIG. 9  is a hollow thickened edge  36  that includes a hollow inner edge area  40  that defines a slot-shaped void  42 . 
     In another alternative embodiment,  FIG. 10  illustrates a thickened edge  36  that is solid. In both  FIGS. 9 and 10 , a radiused edge  44  is provided on the closure panel that resembles the hem flange  26  of prior art closure structures. 
     Referring to  FIG. 11 , the one-piece closure panel  30  is shown in an area where a hinge (not shown) is to be installed. The one-piece closure panel  30  is integrally formed with the inner portion  34  and the outer skin  32 . The thickened edge  36  extends about the one-piece closure panel  30 . In the embodiment shown in  FIG. 11 , the thickened edge  36  is a hollow edge  40  that includes a slot-shaped void  42 . A hinge buttress  54  is integrally formed as part of the inner portion  34 . The hinge buttress  54  is adapted to receive the hinge (not shown) of the closure panel  30 . One or more threaded protrusions  56  may be formed as part of the hinge buttress  54 . The threaded protrusions  56  receive a threaded fastener that is used to connect the hinge to the hinge buttress  54  and inner portion  34  of the one-piece closure panel  30 . 
     The one-piece closure panel  30  is manufactured on a 3-D printing machine that is also be referred to as an additive manufacturing process. In the additive manufacturing process, layers of metal powder are printed onto a printing bed with additional layers of the powdered metal being applied to previously deposited layers. Each layer is cured by applying heat or light that solidifies the printed layer. Selective laser melting (SLM), direct metal laser sintering (DMLS), selective laser sintering (SLS), fused deposition modeling (FDM), fused filament fabrication (FFF), stereo lithography (SLA) and laminated object manufacturing (LOM) may be used to solidify the printed layers. The one-piece closure panel  30  may be oriented in the 3-D printing machine to print the front, the rear, or one of the sides of the one-piece closure panels initially and then build upon the initial deposit. 
     Referring to  FIG. 11 , a spring  60  may be integrally formed between the outer skin  30  and the inner portion  34  to provide additional resilience in selected areas of the one-piece closure panel  30 . The spring element may be a Z-shape, S-shape or an elongated leaf spring element. The spring element  60  may be used to locally strengthen the one-piece closure panel  30  or provide additional resilience and energy absorption. 
     The openings  48  and  50  (shown in  FIG. 8 ) and the threaded protrusions  56  (shown in  FIG. 11 ) may be formed by selective depositing of the printed metal powder or by applying the metal powder over an entire area and then selectively sintering or melting the powder after it is deposited to leave areas that may become voids in the finished one-piece closure panel  30 . The slot-shaped void  42  (shown in  FIGS. 9 and 11 ) may also be formed by selectively depositing and sintering the powdered metal or by depositing the powdered metal throughout the thickened edge or hollow edge  40  and selectively melting or sintering the powdered metal on either side of the slot-shaped void  42 . 
     The embodiments described above are specific examples that do not describe all possible forms of this disclosure. The features of the illustrated embodiments may be combined to form further embodiments of the disclosed concepts. The words used in the specification are words of description rather than limitation. The scope of the following claims is broader than the specifically disclosed embodiments and also includes modifications of the illustrated embodiments.