Abstract:
A method of manufacturing a vehicle body part embeds an insert piece into a foamed layer of the body part by holding the insert piece in a foaming tool using a magnetic force. The magnetic force holds the insert piece into position, eliminating the need for any additional holding structures in the foaming tool. A body part made by this method has improved visual quality, particularly at a transition area between the insert piece and a decorative part.

Description:
REFERENCE TO RELATED APPLICATIONS  
         [0001]    The present invention claims the benefit of German Patent Application No. 103 28 045.6, filed Jun. 23, 2003.  
         TECHNICAL FIELD  
         [0002]    The present invention relates to a vehicle body part and a method of manufacturing a vehicle body part, such as an add-on vehicle body part or a vehicle inner lining.  
         BACKGROUND OF THE INVENTION  
         [0003]    Add-on vehicle body parts form sections of an outer skin of the vehicle after assembly. Add-on body parts may include, for example, vehicle doors and flaps as well as vehicle roof modules and vehicle headliners. The body part may include a foamed layer deposited on a substrate that acts as the outer skin once the body part is attached to the vehicle.  
           [0004]    There is an increasing demand for body parts that allow functional components to be secured thereon while allowing individual components to be exchanged and repositioned. Functional components of this kind are, for example, deposit areas, lockable consoles, screens, lamp systems, loudspeakers, shading systems and the like. To accommodate these types of functional components, inserts are embedded in the foamed layer. These inserts act as fastening elements to secure the functional components to the body part.  
           [0005]    Currently known inserts have several problems, however. The inserts are difficult to position during the process of applying the foamed layer. Moreover, it is difficult to obtain a neat, visually-pleasing transition between the insert and any large-surface decorative part that is also usually provided on the body part (e.g., plastic sheet, textile fabric or sheet metal foil). For this reason, the decorative part is normally in the form of an unbroken sheet, covering an area where the insert is to be located. The decorative part is then later punctured after the body part is substantially complete to accommodate any components to be attached to the insert (e.g., to screw a fastening screw into the insert).  
           [0006]    There is a desire for a method and system that allows a vehicle body part to have fastening elements that are easily positioned during manufacturing of the body part and that provides a flexible, visually pleasing way to attach functional components.  
         SUMMARY OF THE INVENTION  
         [0007]    The invention is directed to a method for positioning inserts, which serve as fastening elements, into a foaming tool in a simple and reliable manner to form a vehicle body part. The invention is also directed to a vehicle roof module and a vehicle headliner having a fastening system for add-on components that is suitable to be used for any desired purpose.  
           [0008]    The method in accordance with one embodiment of the invention includes securing an insert piece, which serves as a fastening member for an external add-on component, via a magnet integrated in a foaming tool. The method also includes introducing a liquid plastic material into the foaming tool, closing the foaming tool, and foaming the plastic material to form a foamed layer. Foaming the plastic material embeds the insert piece into the foamed layer.  
           [0009]    A large-surface decorative part may be placed inside the foaming tool. The decorative part has a hole at a position of the insert piece. The insert piece is then firmly positioned in place on the decorative part by the magnet. The insert piece presses the decorative part against the inner wall of the foaming tool in the vicinity of the hole so that the insert piece seals the hole against leakage of the foamed plastic material through the decorative part.  
           [0010]    The invention further relates to a vehicle roof module and a vehicle headliner that are manufactured by the method described above. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    Further features and advantages of the invention will be apparent from the following description and from the accompanying drawings to which reference is made and in which:  
         [0012]    [0012]FIG. 1 is a top view of an outer side of a vehicle headliner manufactured according to a method of one embodiment of the invention;  
         [0013]    [0013]FIG. 2 is a sectional view of the headliner of FIG. 1 taken along the line II-II;  
         [0014]    [0014]FIG. 3 is an enlarged sectional view of the headliner in the area marked by X in FIG. 2;  
         [0015]    [0015]FIGS. 4 through 7 are sectional views of the headliner according to one embodiment of the invention with various add-on components attached thereon;  
         [0016]    [0016]FIG. 8 is a sectional view of a foaming tool for carrying out the method according to one embodiment of the invention; and  
         [0017]    [0017]FIG. 9 is an enlarged sectional view of a locating bushing in the foaming tool to be employed in the method according to one embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0018]    The invention is generally directed to a method for positioning inserts, which serve as fastening elements, into a foaming tool in a simple and reliable manner to form a vehicle body part. The invention is also directed to a vehicle roof module and a vehicle headliner having a fastening system for any desired add-on components.  
         [0019]    The inserts are positioned and attached to the body part by placing an insert piece, which will serve as a fastening member for external add-on components, using a magnet integrated in a foaming tool. A liquid plastic material is introduced into the foaming tool and the foaming tool is closed. The plastic material is then foamed to form a foamed layer, embedding the insert piece into the plastic material.  
         [0020]    In one possible method of the invention, an inner side of the foaming tool may be designed to be very flat and non-stepped. The flat results in high surface quality of the body part produced by the foaming tool. Moreover, by using magnetic force to hold the insert piece securely in the foaming tool, the invention can eliminate complicated partial vacuum systems, which tend to pull the foam toward a suction channel, for holding the insert piece. This further improves the surface quality and structural quality of the body part.  
         [0021]    In one embodiment, a large-surface decorative part made of, for example, textile fabric, plastic sheet, or aluminum or iron sheet metal, is placed inside the foaming tool before the insert piece is secured inside the foaming tool by the magnet. The decorative part has a hole at a position of the insert piece. The insert piece is then firmly positioned in place on the decorative part by the magnet. The magnet itself is disposed outside a foaming cavity of the foaming tool. The insert piece presses the decorative part against the inner wall of the foaming tool in a vicinity of the hole, thereby forming a seal to prevent any of the foamed plastic material from leaking through the hole both before and during foaming. The insert piece preferably projects through the hole into an opening at the inner side of the foaming tool, thereby positioning the insert piece in a lateral direction. The magnet positions and holds the insert piece in an axial direction.  
         [0022]    The magnet itself may be, for example, a ring magnet that surrounds an opening into which the insert piece projects in sections. The ring magnet ensures a uniform attraction force on the insert piece and prevents the insert piece from tilting when the foamed layer is applied.  
         [0023]    In one embodiment, the insert piece has a flange and a pin projection, such as a headless pin projection, protruding from the flange. If the insert piece uses, for example, a threaded bushing, the magnet additionally has a corresponding projecting pin.  
         [0024]    When particularly high pressures are involved in the foaming process, a certain sealing distance should be provided between the insert piece and the area of the decorative part that contacts the insert piece. This distance prevents the foamed plastic material from reaching the hole in the decorative part. No separate sealant is needed between the insert piece and the decorative part. If the insert piece is cylindrical, the part of the flange on the insert piece that directly contacts a rear side of the decorative part should have a diameter that is 1.5 to 3 times larger than the diameter of the hole to ensure proper sealing. This diameter substantially corresponds to a diameter of the pin projection.  
         [0025]    The invention is particularly suitable for roof modules, hardtops, and headliners as well as other outer and inner lining parts, paneling parts and structural components of motor vehicles. In one embodiment, the foamed layer can be produced by, for example, structural reaction injection molding (S-RIM) or long fiber injection (LFI) methods.  
         [0026]    In one embodiment, the insert piece includes an internal thread or an external thread. An elongated profiled part may also be employed as the insert piece. Using an elongated profiled part as the insert piece allows a given add-on component to be secured at any desired point along the profiled part, similar to a rail system. A profile in the profiled part is preferably open toward an outer side of the decorative part.  
         [0027]    In accordance with one embodiment, when the body part is a headliner, a plurality of spaced profiled parts is distributed over the headliner so that add-on components may be attached at any desired place.  
         [0028]    The invention further relates to a vehicle roof module and a vehicle headliner that are manufactured by the method in accordance with the invention.  
         [0029]    Referring to the figures, FIG. 1 illustrates a vehicle headliner manufactured by a method in accordance with one embodiment of the invention, which will be explained in greater detail below. An exterior (visible) side of the headliner is formed by a decorative part  10 , such as a textile fabric, a sheet of any desired material, or a metal or plastic foil. As shown in FIGS. 2 and 3, the decorative part  10  is provided with a foamed layer  12  made of a foamed material, such as polyurethane, on its rear side. A reinforcing inset  14 , such as a fiber mat or the like, may be embedded in the foamed layer  12 .  
         [0030]    A plurality of parallel insert pieces in the form of open hollow profiles  16  may extend parallel to a longitudinal axis A of the vehicle. The profiles  16  may have an Ω-shaped cross-sectional form, as shown in FIG. 3. The profile  16  has a pair of flat lateral flanges  18  that engage the exterior side of the decorative part  10 . The profile  16  further has a narrow through-opening  20  and a widened undercut portion  22 .  
         [0031]    The profiles  16  acting as the insert pieces make it possible to attach add-on components to the body part. Possible add-on components include, for example, longitudinally adjustable and exchangeable consoles  24  (FIG. 4) for linking other add-on components to the profiles  16 , screens  25  (FIG. 4), roller blinds or sunshade systems  26  (FIG. 5), loudspeakers  28  (FIG. 6) or light sources  30  (FIG. 7). As noted above, the shape of the profiles  16  allow the add-on components to be attached from the interior of the vehicle at any desired location.  
         [0032]    To ensure that electricity can be supplied to a given add-on component at any desired location, current-carrying contacts  32  may be arranged within the undercut portion  22  along the length of the profile  16  (FIG. 3).  
         [0033]    [0033]FIGS. 8 and 9 illustrate one embodiment of a foaming tool that can be used to manufacture the body part described above as well as other add-on vehicle body parts, such as roof modules, doors and flaps. The foaming tool comprises an upper part  34  and a lower part  36 . When the upper and lower parts  34 ,  36  of the foaming tool are moved toward each other, they form a foaming cavity between them that can be filled with, for example, foamed polyurethane.  
         [0034]    The example in FIG. 8 shows a roof module formed by the foaming process. In this example, a deep-drawn thermoplastic sheet  38  that has been dyed throughout or an aluminum sheet is placed inside the lower part  36  of the foaming tool to engage an inner side of the lower part  36 . The entire surface of the sheet  38  engages with the lower part  36 . A sheet-like decorative part  40 , similar to the decorative part  10  described above, is secured to an inner side of the upper part  34  of the foaming mold.  
         [0035]    Next, substantially cylindrical insert pieces  42  are attached to the upper part  34  of the foaming mold from an inner side of the decorative part  40 . A decoration support  62  surrounding a border area of the upper part  34  clamps the decorative part  40  to the foaming mold by the edges of the decorative part  40 . The cylindrical insert piece  42  has a flange  44  that engages an inner side of the decorative part  40 . A threaded bolt  46  protrudes from this flange  44  through a prefabricated hole in the decorative part  40  and into an opening  48  in a holder bushing  50  in the upper part  34  of the foaming mold. The diameter of the opening  48 , the diameter of the threaded bolt  46 , and the diameter d of the hole in the decorative part  40  are substantially the same.  
         [0036]    [0036]FIG. 9 shows the holder bushing  50  in more detail. An accommodation space  52  is adjacent to the opening  48  at its lower end face to accommodate a ring magnet  54  (FIG. 8). The accommodation space  52  is closed by a plastic ring  56 .  
         [0037]    As also shown in FIG. 8, lateral extensions  58  are included in the region of the flange  44  and are spaced apart from the decorative part  40 . The lateral extensions enhance the anchoring of the cylindrical insert piece  42  in a foamed layer  60 , which is similar to the foamed layer  12  described above.  
         [0038]    The diameter D of the surface of the flange  44 , which contacts the decorative part  40 , is approximately 1.5 to 3 times as large as the diameter d of the hole in the decorative part  40  to ensure secure sealing and prevent leakage of the plastic material forming the foamed layer  60  through the hole.  
         [0039]    In one embodiment, the cylindrical insert piece  42  is made of metal or has a metal inlay to ensure that the cylindrical insert piece  42  will be attracted to the ring magnet  54 , thereby pressing the flange  44  firmly against the decorative part  40 . The decorative part  40  is in turn pressed firmly against the inner side of the upper part  34  of the foaming mold. The cylindrical insert piece  42  is thus firmly mounted in position in the upper part  34  of the foaming mold in both the axial and radial directions.  
         [0040]    Once the cylindrical insert piece  42  is firmly in position, a liquid material, such as polyurethane, is applied onto the rear side of the sheet  38 . If desired, reinforcing glass fibers may be added to the liquid material by, for example, the LFI method.  
         [0041]    The upper and lower parts  34  and  36  of the foaming mold are then moved toward each other. The liquid material reacts and foams, filling the foaming cavity between the upper and lower parts  34 ,  36  to connect the decorative part  40  with the sheet  38  via the foamed layer  60 . The cylindrical insert piece  42  is thus firmly embedded in the foamed layer  60 .  
         [0042]    The cylindrical insert piece  42  presses against the decorative part  40  so firmly that no foamed material seeps between the cylindrical insert piece  42  and the decorative part  40  or escapes from the hole in the decorative part  40 . This tightness is attained without having to apply any elastic sealants on the inner side of the upper part  34 . Thus, the resulting body part does not have any seals that would be subject to constant wear and deterioration.  
         [0043]    Note that the cylindrical insert piece  42  itself does not need to be made of metal in order to be positioned by the magnet  54 . In the insert piece configuration shown in FIG. 3, for instance, an auxiliary fastening element AX may be temporarily placed in the insert piece (such as in the hollow profile  16 ) solely for achieving the fastening. The auxiliary fastening element AX may be, for example, a swiveling tenon block having a pin-line extension placed into the insert piece to project into the opening  48 .  
         [0044]    It should be appreciated that in the example shown in FIGS. 1 through 3, it is possible to eliminate the flanges  18 , allowing the widened undercut portion  22  of the hollow profile  16  to contact the inner side of the decorative part  10 . It is further not necessary for the decorative parts  10 ,  40  to be formed as single layers. Instead, the decorative parts  10 ,  40  may be in the form of multi-layer sheets having a thickness of a few millimeters. The decorative part  10 ,  40  may, for example, have a reinforcing layer similar to the reinforcing inset  14  shown in FIG. 3 provided on its rear side. Also note that for the embodiment shown in FIGS. 1 through 3, any holes in the foaming tool for accommodating the profiles  16  (i.e., the insert pieces) take the shape of long slots. These holes would be formed before the decorative part  10  is introduced into the foaming tool.  
         [0045]    It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that the method and apparatus within the scope of these claims and their equivalents be covered thereby.