Abstract:
A roof module comprises an outer shell and a foamed inner shell. The outer shell has a rim including an edge of cut and the inner shell extends as far as on the edge of cut. There is also proposed a method of producing such a roof module.

Description:
REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present invention is a divisional of U.S. patent application Ser. No. 10,225,970, filed Aug. 22, 2002, and which claims the benefit of German Patent Application No. 101 41 242.8, filed Aug. 23, 2001. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The invention relates to a roof module comprising an outer shell and a foamed inner shell. The invention further relates to a method of producing such a roof module.  
           [0003]    Hitherto, the roof module has been produced by placing the outer shell, the rim of which is configured with an excess width, into a foaming mold and subsequently applying the inner shell onto the inner side of the outer shell by foaming. In the process, the inner shell extends as far as to the rim of the outer shell. After foaming, the rim of the outer shell together with the inner shell applied by foaming is cut to size. Cutting to size of the outer shell provided with the inner shell is a difficult operation during which a lot of dirt occurs. Moreover, that part of the inner shell which is on the cut-off rims of the outer shell, represents cuttings, this increasing the production costs. Finally, the roof module has exposed edges of cut after it has been cut to size.  
           [0004]    It is the object of the invention to improve a roof module of the type initially mentioned as well as a method of its production to the effect that fewer cuttings and, hence, lower production costs are produced and that the roof module does not have edges of cut which are exposed.  
         SUMMARY OF THE INVENTION  
         [0005]    According to the invention, a roof module is provided which comprises an outer shell and a foamed inner shell. The outer shell has a rim including an edge of cut and the inner shell extends as far as on the edge of cut. Such a roof module may be obtained by the following method: firstly, an outer shell is made available. Then the rims of the outer shell are cut to size. As a next step, the outer shell is placed in a foaming tool and a curable material is applied onto the outer shell. Subsequently the foaming tool is closed, a seal n the foaming tool pressing against the rim of the outer shell from outside towards inside. The curable material hardens, it reaching the edges of cut on the rim of the outer shell. The roof module produced in this way does not have to be cut to size after the foaming operation. Consequently, only so much of the material for the inner shell has to be introduced as is actually required for it; no loss occurs. As the inner shell extends as far as on the edges of cut at the rim of the outer shell, the edges of cut—which have been produced prior to foaming on cutting the outer shell to size—are sealed.  
           [0006]    According to a preferred embodiment, it is provided for that the outer shell is configured with an undercut on its rim. This can be obtained in that, on producing the roof module, the seal is pressed elastically against the outer shell when the foaming tool is being closed and plastically deforms the outer shell in this process. It is not required in this procedure to provide slider elements in the foaming tool which usually are required for producing the undercut on foaming. It is not required either that the outer shell has the undercut already before foaming. This, in fact, could be managed during production of the outer shell only with large expenditure.  
           [0007]    Advantageous designs of the invention will be apparent from the subclaims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 shows in a broken sectional view a foaming tool in the open state, with an inserted outer shell according to a first embodiment.  
         [0009]    [0009]FIG. 2 shows the foaming tool of FIG. 1 in the closed state, an inner shell being applied to the outer shell by foaming;  
         [0010]    [0010]FIG. 3 shows a detailed of FIG. 2 on an enlarged scale;  
         [0011]    [0011]FIG. 4 shows in a broken sectional view a foaming tool in the closed state, with an outer shell and an inner shell applied by foaming, according to a second embodiment; and  
         [0012]    [0012]FIG. 5 shows a detail of FIG. 4 on an enlarged scale. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    In FIGS.  1  to  3  these is schematically shown a foaming tool  10  which consists of an upper part  12  and a lower part  14 . Received in the lower part  14  is an outer shell  16  which will be a part of the roof module and which may consist of aluminum or plastics, for instance. The outer shell  16  has a rim  18  that ends at an edge of cut  20 . The edge of cut is produced in the course of cutting the outer shell  16  to size.  
         [0014]    In the lower part  14  of the foaming tool  10 , there is received a seal  22  which has a base section  24  anchored in the lower part  14  and a head section  26  associated to the rim  18  of the outer shell  16 . The seal  22  is made of a material which on the one hand has sufficient resistance to pressure and temperature with regard to the foaming operation and which is elastically deformable, on the other.  
         [0015]    The upper part  12  of the foaming tool  10  has a sealing section associated to the rim  18  of the outer shell  16  and the head section  26  of the sealing  22 . The sealing section consists of an end surface  30  and a pressure surface  32 . The end surface  30  extends approximately perpendicular to the direction along which the upper part  12  and the lower part  14  of the foaming tool  10  are movable relative to each other. The pressure surface  32  extends obliquely to the end surface.  
         [0016]    When the foaming tool  10  is transferred from the open position shown in FIG. 1 into the closed position shown in FIG. 2, the obliquely extending pressure surface  32  engages the head section  26  of the elastic seal  22  and moves this head section to the left due to a wedge effect. In so doing, the rim  18  resting at the head section  26  of the seal  22  is likewise moved to the left. When the foaming tool is in the closed state, the end surface  32  rests tightly on the upper side of the head section  26  of the seal  22 . The edge of cut  20  of the rim  18  of the outer shell  16  lies opposite the end surface  30  at a small distance (see in particular FIG. 3).  
         [0017]    Prior to closing the foaming tool  10 , there has been applied onto the outer shell  16  a foamable material which cures when the foaming tool has been closed, so that it forms an inner shell  34  on the inner side of the outer shell  16 . As can be taken in particular from FIG. 3, the inner shell extends along the rim  18  as far as on the edge of cut  20  which is covered by the material of the inner shell  34 . In the region where the material of the inner shell  34  rests at the head section  26  of the seal  22 , namely between the edge of cut  20  on the outer shell  15  and the end surface  30  of the upper part  12  of the foaming tool, the inner shell extends away from the edge of cut in extension of the outer surface of the outer shell. The material which is present there, seals the edge of cut  20 . As the head section  26  of the seal has moved the rim  18  of the outer shell  16  towards inside on closing the foaming tool, the rim  18  of the outer shell  16  rests at the head section  26  of the seal  22  with a sufficiently high force, so that the material of the inner shell  34  cannot enter the region between the rim  18  of the outer shell  16  and the head section  26  of the seal  22  and, hence, cannot emerge from the foaming tool. With this, the rims of the roof module formed by the outer shell  16  and the inner shell  34  are smooth after foaming, without the need of a subsequent cutting operation.  
         [0018]    In FIGS. 4 and 5 there is shown a roof module according to a second embodiment. The same reference numerals will be used for the components known from the first embodiment, and reference is made to the above explanations.  
         [0019]    The difference between the first and the second embodiment is that in the second embodiment the pressure surface  32  is inclined more, so that upon closing the foaming tool the head section  26  of the seal  22  is moved to the left to a greater extent. In the process, the rim  18  of the outer shell  16  is moved to the middle of the outer shell  16  so far that the outer shell is undercut, i.e., the edge of cut lying further inwardly than does the rim  18  in the region of the transition to the horizontally extending middle section of the outer shell  16 . The deformation of the rim  18  on closing the foaming tool is preferably a plastic one, so that after opening the foaming tool only a slight spring-back occurs which does not impose an exceed load on the fit of the inner shell  34  on the outer shell  16 . It is e.g. in the region of the rear flap of a vehicle provided with the roof module where the undercut can be of advantage.  
         [0020]    The foregoing description is only exemplary of the principles of the invention. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, so that one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason, the following claims should be studied to determine the true scope and content of this invention.