Abstract:
An interior trim panel for a vehicle door is provided according to alternative methods. The interior trim panel includes a bolster to which a polyurethane skin is molded by a spraying operation. Expanded polyurethane foam is sprayed over the polyurethane skin and a backing panel is either integrally formed or assembled to the polyurethane foam layer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a division of U.S. application Ser. No. 10/911,121 filed Aug. 4, 2004, now U.S. Pat. No. 7,273,572 issued Sep. 25, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an interior trim panel for a vehicle door and a method of making an interior trim panel. 
     2. Background Art 
     Vehicle designers may design the specified interior trim for vehicle doors that include trim and bolster portions and other soft padded areas. Padding is frequently specified in certain areas, such as in areas near arm rests or in areas where vehicle occupants make contact with their hands or arms. Interior trim is frequently designed with multiple appearance effects and feel by providing different areas with different trim finishes. For example an interior trim panel of a door may have wood appearance portions, cloth surfaces, leather portions, and various textile coverings. 
     Panel portions having different physical characteristics may require multiple assembly operations to join adjacent parts together by sealing or in conjunction with adhesives. Labor costs generally tend to increase as the number of assembly operations required to prepare an interior trim panel for a door increase. Secondary manufacturing operations require additional tooling, fixtures and labor expense. 
     There is a need for an interior trim panel for a door and a method of making an interior trim panel having different portions that have a combination of different surface finishes. Some surface coverings may be supported by a relatively rigid bolster panel. There is a further need to provide such a method and article in a one-piece construction that minimizes material and labor costs. It is important that a high quality interior panel be provided that reduces assembly time and the number of assembly operations required to provide the interior trim panel for a door. 
     The above problems and needs are addressed by applicants&#39; invention as summarized below. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention relates to a method of making an interior trim panel for a vehicle door. The method may comprise the steps of vacuum forming a bolster and inserting the bolster into a mold. A polyurethane skin is sprayed onto the mold and over one side of the bolster to form a skin/bolster assembly. An expandable polyurethane elastomer is sprayed onto the polyurethane skin. The elastomer/skin/bolster assembly is inserted into a reaction injection mold. A glass fiber material is inserted into the reaction injection mold and polyurethane is then injected into the reaction injection mold to bond an elastomer/skin/bolster assembly and the glass fiber to form a glass fiber-reinforced layer/foam/skin/bolster assembly. 
     According to other aspects of the invention, the glass fiber material may be a glass fiber mat or, alternatively, a quantity of chopped glass fiber. The bolster may have a decorative element on the side opposite to the side on which the polyurethane skin is sprayed. 
     An alternative method of making an interior trim panel of a vehicle door may comprise forming a bolster in a vacuum forming process, inserting the bolster in a mold and spraying a urethane skin onto the mold over one side of the bolster to form a skin/bolster assembly. An expandable polyurethane elastomer layer may then be sprayed onto the polyurethane skin to form a foam/skin/bolster assembly. In the alternative method, a substrate is assembled to the elastomer layer of the foam/skin/bolster assembly. 
     According to other aspects of the latter alternative, the step of assembling the substrate may further comprise placing the substrate on the foam layer while the elastomer layer is curing so that the plate becomes adhered to the foam layer. Alternatively, the step of assembling the substrate may further comprise applying an adhesive between the foam layer of the foam/skin/bolster assembly and the substrate. 
     According to another aspect of the invention, an interior trim panel for a vehicle door is provided. The interior trim panel includes a bolster, a urethane skin layer covering one side of the bolster. A portion of the skin layer extends outwardly from the bolster. An expanded polyurethane layer is bonded to the opposite side of the urethane skin layer from the bolster and a backing layer is attached to the opposite side of the expanded polyurethane layer from the urethane skin layer. 
     Other aspects of the invention as it relates to an interior trim panel for a vehicle door may include providing a glass fiber-reinforced layer of relatively rigid polyurethane that is applied in a reaction injection molding operation. A cross-section of the trim panel at the bolster may comprise a multi-layered structure comprising the relatively rigid bolster panel, the urethane skin layer applied over the bolster panel, the expanded polyurethane layer, and the cover layer that is attached over the expanded polyurethane layer. A cross-section of the trim panel outboard of the bolster may comprise a multi-layered structure including the urethane skin layer, the expanded polyurethane layer, and the fiber-reinforced urethane layer that is attached to the expanded polyurethane layer. A cover layer is also attached over the fiber-reinforced urethane layer. Alternatively, the portion of the trim panel outboard of the bolster may comprise a multi-layered structure comprised of the urethane skin layer, the expanded polyurethane layer, the fiber-reinforced urethane layer bonded to the expanded polyurethane layer, and the cover layer that is attached over the fiber-reinforced urethane layer. 
     These and other aspects of the present invention will be better understood in view of the attached drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an interior perspective view of a vehicle door having an interior trim panel made according to the present invention; 
         FIG. 2  is a cross-sectional view of a bolster panel; 
         FIG. 3  is a cross-sectional view of a bolster panel in a mold on which a polyurethane skin layer is sprayed; 
         FIG. 4  is a diagrammatic cross-sectional view showing the bolster panel in a mold to which a polyurethane skin layer and an expanded polyurethane foam layer is applied; 
         FIG. 5  is a diagrammatic cross-sectional view showing a cross-sectional view of a foam/skin/bolster assembly being placed in an open reaction injection molding die with a glass fiber reinforcement; 
         FIG. 6  is a diagrammatic cross-sectional view of the mold shown in  FIG. 5  and its closed position and also illustrates the injection of urethane into a cavity containing the glass fiber reinforcement; 
         FIG. 7  is a diagrammatic cross-section view taken along the line  7 - 7  in  FIG. 1  of an interior trim panel after completion of the molding step illustrated in  FIG. 6 ; 
         FIG. 8  is a diagrammatic cross-sectional view showing the bolster panel in a mold to which a polyurethane skin layer and an expanded polyurethane foam layer is applied; 
         FIG. 9  is a diagrammatic cross-sectional view showing a mold in which an injection mold plate is secured to the foam/skin/bolster prior to removal from the tool; and 
         FIG. 10  is a diagrammatic cross-sectional view showing the assembled plate and foam/skin/bolster assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , a vehicle door  10  is shown from the inside to illustrate the interior trim panel  12 . Interior trim panel  12  includes a bolster  16  which is a pre-formed insert. The bolster  16  is a styling design element of the door that may have a different composition and surface finish than other parts of the interior trim panel  12 . The bolster may be formed, for example, by a vacuum-forming process and may have a wood-like appearance, a metallic layer, or glossy finish. 
     Referring to  FIG. 2 , a bolster  16  is shown to include an edge rib  18 . Edge rib  18  appears to be raised relative to the other portions of the bolster  16 , but in actuality defines an indentation in the interior trim panel  12 . Such indentations may be used to simulate sewing seams in interior panel designs. When the bolster  16  is attached to the interior trim panel  12 , the edge rib  18  appears as a recess in the interior trim panel  12 . 
     Referring to  FIGS. 3 and 4 , the bolster  16  is loaded into an open mold forming tool  22  with the edge rib  18  being received onto protrusions  24  in the tool  22 . A spray gun  26  sprays or otherwise dispenses a polyurethane reactant mixture to form an polyurethane skin  28  over the bolster  16  and on outboard areas  30  of the forming tool  22 . This subassembly may be referred to as a skin/bolster assembly. 
     Referring to  FIG. 4 , the spray gun  26  dispenses expanded foam polyurethane  32  to form a layer of foam polyurethane on the opposite side of the skin  28  from the bolster  16 . The spray gun  26  may be the same spray gun used to dispense the skin or may be an interchangeable spray head. If an interchangeable spray head is used, an articulated robot arm may be used to manipulate either spray head. 
     Referring to  FIG. 5 , a closed mold  36  is provided that may receive the foam/skin/bolster assembly. The foam/skin/bolster assembly must be removed from the tool  22  and loaded onto a lower mold  38  of the closed mold  36 . An upper mold  40  is also provided as part of the closed mold  36 . A glass fiber reinforcement  42  comprising either a glass fiber mat or chopped glass fiber is loaded into a cavity  44  defined by the upper mold  40 . A port  46  is provided in the upper mold  40  for the injection of a reactant polyurethane mixture. 
     Referring to  FIG. 6 , the mold  36  is shown in its closed position with the upper mold  40  engaging the lower mold  38 . A source of polyurethane  48  is provided to inject a reactant polyurethane mixture into the cavity  44 . The reactant polyurethane mixture binds to the glass fiber reinforcement  42  and also adheres to the expanded foam polyurethane layer  32 . 
     Referring to  FIG. 7 , the completed interior trim panel  12  is shown to include a bolster  16  over which a skin layer is molded. The skin layer  28  extends outboard of the bolster  16 . An expanded foam polyurethane layer  32  is bonded to the polyurethane skin  28 . The glass fiber reinforced layer  50 , including the glass fiber reinforcement  42 , is molded over and bonded to the expanded foam polyurethane layer  32  to complete the basic structural elements of the interior trim panel  12 . Other components may then be assembled to the trim panel  12 . 
     Referring to  FIG. 8 , an alternative embodiment is illustrated. The steps illustrated in  FIGS. 2-4  are repeated, resulting in the structure illustrated in  FIG. 8 . The tool  22  supporting the bolster  16  has been coated with the polyurethane skin  28  that is in turn covered by the expanded polyurethane layer  32 . The spray gun  26  (or another adhesive applicator) may be used to dispense an adhesive  52  onto the expanded foam polyurethane layer  32 . 
     Referring to  FIG. 9 , a preformed plate that may be an injection molded plate is secured to the expanded foam polyurethane layer  32  by the adhesive  52  applied in the step shown in  FIG. 8 . Alternatively the plate  56  could be assembled to the expanded foam polyurethane  32  without an adhesive if it is placed on the expanded foam polyurethane layer  32  before it is cured and still inherently adhesive. 
     Referring to  FIG. 10 , the completed interior trim panel  12  is shown to include a bolster  16  to which a polyurethane skin  28  is molded. A layer of expanded foam polyurethane  32  is applied to the polyurethane skin  28 . Finally, the plate  56  is adhered by adhesive or by inherent adhesive properties to the expanded foam polyurethane layer  32 . 
     While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.