Abstract:
A floor panel having a first and second layer. The first and second layer including polypropylene resin. The floor panel also including a foam layer located between the first and second layer. The first and second layer are bonded along an edge region to encapsulate the foam layer. In addition, the first layer defines a recess in a middle portion of the floor panel, wherein the recess includes a region where the first and second layer are bonded together.

Description:
BACKGROUND  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to a floor panel especially adapted for a motor vehicle and method for producing the same.  
         [0003]     2. Description of Related Art  
         [0004]     Typically, floor panels for vehicles, such as the panel that covers a rear tire in the trunk of a sport utility vehicle are typically made of a wood or compressed fiber material. The compressed panels provide a fairly lightweight and low cost option for covering the spare tire and vehicle underbody from the user. In addition, materials are usually attached to the compressed boards allowing them to easily match the interior of the vehicle or other compartment trim.  
         [0005]     However, often over time the compressed board panels will absorb water or fatigue causing eventual warping or failure of the board. More recently, floor panels have been made from blow molded polypropylene. However, these panels are often heavier than the compressed board panels and offer similar durability.  
         [0006]     In view of the above, it is apparent that there exists a need for an improved floor panel and method for producing the same.  
       SUMMARY  
       [0007]     In satisfying the above need, as well as overcoming the enumerated drawbacks and other limitations of the related art, the present invention provides an improved floor panel and method for producing the same.  
         [0008]     The floor panel of this invention has a first and second layer. The first and second layer including about 45% polypropylene resin and about 55% glass fiber. The floor panel also including a foam layer, such as an expanded polypropylene foam, located between the first and second layer.  
         [0009]     The first and second layer are bonded along their edges to encapsulate the center foam layer. The bonded edges may form a flange extending beyond the foam layer. In addition, the first layer defines a recess in a middle portion of the floor panel wherein the recess includes a region where the first and second layer directly contact one another and in such a region are bonded together. Further, the floor trim panel may include an array of recesses wherein each recess forms a bonded region between the first and second layer and each bonded region is preferably less than 12 inches from another bonded region.  
         [0010]     In another aspect of the present invention, a method for manufacturing the panel is provided. A first sheet of so-called super light material is heated and positioned within the tooling. A foam sheet is located over the first sheet and aligned with respect to the tool. A second super light material sheet is heated and positioned over the foam sheet. The tool is closed, applying pressure to the second sheet thereby bonding the second sheet to the first sheet and encapsulating the foam layer. Further, as mentioned above, recesses may be formed through the foam sheet forming additional bonded regions between the first and second sheet.  
         [0011]     Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a top view of the floor trim panel in accordance with the present invention;  
         [0013]      FIG. 2  is a sectional side view along section line  2 - 2  in  FIG. 1 ;  
         [0014]      FIG. 3  is a sectional side view of the floor panel section along line  3 - 3  in  FIG. 1 ;  
         [0015]      FIG. 4  is a flow chart of a method for producing the floor panel in accordance with the present invention;  
         [0016]      FIG. 5  is a side view of the heating process in accordance with the present invention; and  
         [0017]      FIG. 6  is a sectional side view of the forming process in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0018]     Referring now to  FIG. 1 , a floor panel embodying the principles of the present invention is illustrated therein and designated at  10 . As its primary components, the floor panel  10  includes a first layer  12 , a second layer  14 , and a foam layer  16 .  
         [0019]     The first and second layer  12  and  14  are preferably made from a super light material, such as Azdel™ material manufactured by General Electric Plastics. One example of super light material is made of 35-55% polypropylene resin and 45-65% fibrous filler material, more preferably 55% glass fiber and about 45% polypropylene resin. The super light material may be supplied in sheets of various weights ranging from 800 to 2000 grams per square meter. The foam layer  16  is fully enclosed by the first layer  12  and the second layer  14 . The foam layer  16  is made of an expanded polypropylene foam. The first layer  12  is bonded to the second layer  14  at an edge region  18  around the perimeter of the floor panel  10 . The bond around the edge region  18  fully encapsulates the foam layer  16 . In addition, a middle portion  19  of the floor panel  10  may have one or more recesses  20  forming a region  22  where the first layer  12  extends through the foam layer  16  and bonds with the second layer  14 . Creating multiple recesses  20  with bonded regions  22 , helps to prevent delamination and improve the rigidity of the floor panel  10 . Preferably, each bonded region  22  is less than 12 inches from another bonded region  22  or the edge region  18 .  
         [0020]     Now referring to  FIG. 2 , a cross-sectional view is shown along line  2 - 2  of  FIG. 1 . As discussed previously, the foam layer  16  is shown located between the first layer  12  and the second layer  14 . Further, an edge region  18  of the first layer  12  and second layer  14  are bonded forming a flange  24  extending from the foam layer  16 . For a typical panel  10 , the thickness of the first layer  12 , the second layer  14  and foam layer  16  combined is preferably about 19 millimeters. While the thickness at the edge region  18  where the first layer  12  is bonded to the second layer  14  is about 3 millimeters thick. The flange  24  formed at the edge region  18  extends about 12 millimeters from the foam layer  16  and fully encapsulating the foam layer  16 .  
         [0021]     Now referring to  FIG. 3 , a cross-sectional view along line  3 - 3  of  FIG. 1  is provided. A profile of the recess  20  is provided more detail in this cross-sectional view. The recess  20  is formed by a portion of the first layer  12  extending through the foam layer  16  and bonding with the second layer  14 . The bond extends along region  22  of the recess  20 . The recess  20  has a generally conical shape with a surface angle of 20° with respect to the surface of the bonded region  22 . The 20° angle provides ease of insertion and removal for tooling. The bonded region  22  has a diameter of 15 millimeters and a thickness of about 3 millimeters along the bonded region  22 . While the generally conical shape provides for ease of manufacture, other shapes or even troughs may be used to form a recess where the first and second layer  12 ,  14  are bonded to prevent delamination.  
         [0022]     Now referring to  FIG. 4 , a flow chart of a method  30  for making a floor panel in accordance with the present invention is provided. The method  30  starts in block  32  where a first sheet of super light material is heated to a temperature of approximately 400° F. The first sheet is placed on the lower tooling as noted by block  34 . In block  36 , a foam sheet is positioned over the first sheet of super light material. The foam sheet must be accurately positioned during the forming process. Accurate positioning can be achieved utilizing swing arm locators or a laser beam projection. The swing arm locators can be moved into the tooling to align the sheet and then swung out prior to the close of tooling. Similarly, the laser beam projection would project beams into the tooling to visually aid in alignment of the foam sheet. In block  38 , a second sheet of super light material is heated to a temperature of approximately 400° F. The second sheet of super light material is placed over the foam sheet, as denoted by block  40 . In block  42 , the upper tool is closed applying pressure on the first sheet of super light material, the second sheet of super light material, and the foam sheet. Very low pressure is required to form the panels, therefore, aluminum tooling can be used in production while providing solid tool life. This can provide significant cost advantages and ease of tool maintenance. The pressure used to form the panels is approximately 10 to 50 pounds per square inch.  
         [0023]     Now referring to  FIG. 5 , a side view of the heating process is provided. A first sheet  52  and a second sheet  54  are shown being heated in an oven  50 . The oven  50  is a conveyor-type oven where the first and second sheet  52 ,  54  are translated through the oven  50  on a conveyor  56 . Heating elements  58  may be provided above and below the conveyor to heat the first and second sheet  52 ,  54  to a temperature of approximately 400° F.  
         [0024]     Now referring to  FIG. 6 , the first sheet  52  is taken from the conveyor  56  and is positioned on the lower portion  62  of the tooling  60 . Next, a foam sheet  64  is located on the first sheet  52 . The foam sheet  64  is aligned relative to the tooling  60 . The second sheet  54  is then located on top of the foam sheet  64  and the first sheet  52 . The top portion  66  of the tooling  60  closes on the second layer  54  applying approximately 10 to 50 pounds per square inch of pressure to the assembly. The heat of the first and second sheet  52 ,  54  and the pressure provided by the tooling  60  forms a bond between the first and second sheet  52 ,  54 , for example, along the edge regions  18  and the bonded regions  22  of  FIG. 1 . Further, a bond is formed both between the first sheet  52  and the foam sheet  64 , and between the second sheet  54  and the foam sheet  64 . The result is a rigid lightweight floor panel with a very low thermal expansion coefficient.  
         [0025]     As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from the spirit of this invention, as defined in the following claims.