Abstract:
The aim of the invention is to create a centering device having a simple structure for flat components ( 3 ), especially glass panels, which at least along their lateral edges can be surrounded by a plastic frame ( 4 ) by injection/foaming or encapsulation. To this end the invention provides for the centering device ( 16 ) to be embodied by springs ( 18  and  19 ) having the same elastic constant which are positioned opposite each other and both engage the component ( 3 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a centering device for flat components, glass panels in particular, which can be surrounded at least along their lateral edges by a synthetic frame by injection/foaming or encapsulation. 
     2. Description of the Related Art 
     Such components in the form of glass panels for sliding roofs, rear windows, front windows, side windows or similar components are being installed increasingly in vehicles. In this situation the glass panel inside the roof or window opening is as large as possible such that the synthetic frame enclosing the glass panel made of a thermoplastic synthetic material or polyurethane foam material should be as narrow as possible. This synthetic frame of the glass sliding roof also serves to fasten mountings such as brackets to which the drive mechanism for opening the glass sliding roof is hinged, in particular when the glass sliding roof is utilized as a wind-up or turn-up roof or side panels with fastenings. 
     Substantial significance is attached to fastening the synthetic frame together with the mountings, as the glass panel of the glass sliding roof is to be mounted flush with the roof surface for aerodynamic reasons. The synthetic frame is according provided essentially on the circumferential edge and on a narrow region on the underside only of the synthetic frame. Also, the synthetic frame functions as mounting for a circumferential seal to ensure reliable sealing here. 
     A circumferential groove is also generally provided on the synthetic frame for sealing purposes. Yet this arrangement requires a very precise foaming or extrusion tool, since the distance between groove floor and the glass panel contour at the four circumferential side edges of the synthetic frame can be a few millimeters only on account of the preferred narrow structure, such that very precise positioning of the component, in particular the glass panel inside the tool, is required during manufacturing. The centering device required for fabrication should also not interfere with the run of foam of the synthetic material during the extrusion or foaming procedure so that the contact surfaces do not need to be oversized. 
     Furthermore, in the case of previous manufacturing processes employing customary manual centering in the foaming tool there has been the drawback of a higher cycle time and the high risk of accident. Additionally, the dimensional accuracy with use of mechanically coupled limit stops through the plurality of tools is often inadequate, in particular when elongations and thus certain dimensional inaccuracies can occur in the tool and with heat accumulation during manufacture. Because of this burrs, which require a large degree of retouching work, can occur at the edges of the synthetic frame. 
     SUMMARY OF THE INVENTION 
     The objective of the invention is accordingly to create a simply structured centering device for flat components, in particular for a glass panel, which avoids the present disadvantages and lowers tool costs in particular, as well as offering greater dimensional accuracy with less refinishing expense. 
     The synthetic frame for extruding/foaming can be manufactured simply and precisely centered by means of the proposed centering device. In particular, expensive mechanisms or couplings on the tool or for the centering device can be dispensed with in this case. The centering device is therefore essentially integrated into the foaming tool and exhibits a very simple structure. In addition, this effectively produces a very uniform run of foam, such that a complete wetting of the glass panel at the edges is attained. Also, the stability between the glass panel and the synthetic frame is consistently increased, such that the overall quality of the prefabricated part increases. 
     It is ensured in particular that the external contours of the component, in particular a glass sliding roof, are kept to exactly. This substantially lowers the expense for refinishing work on the external contour or deburring of the outer edges. In particular, with the simplest structure an exact relative assignment is achieved by centering the springs arranged in pairs, such that in a preferred embodiment of a glass sliding roof uniform seal installation and thus overall improved sealing of the roof opening is attained. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment of the invention will now be explained and described hereinbelow in greater detail with reference to the diagrams, in which: 
     FIG. 1 is a general illustration of a sliding roof for vehicles with a glass panel as example of a flat component to be inserted into a tool; 
     FIG. 2 shows the glass sliding roof according to FIG. 1 during manufacture in the foaming tool, and 
     FIG. 3 is a diagrammatic illustration of a centering device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates a glass sliding roof  1  as example for application for installation in a roof opening  2  of a vehicle, glass sliding roof  1  essentially comprises a glass panel (here as representatives example of a flat component  3 ) which is surrounded on the outer edge or lateral edges by a synthetic frame  4 , preferably made of PU foam. This frame  4  is extruded or foamed in a foaming tool (cf. FIG. 2) on the outer edge of glass panel  3 . Mountings  5 , preferably angle plates, are also extruded at the same time, such that on the one hand the distortion resistance is increased and on the other hand fastening on the drive mechanism for sliding or raising glass sliding roof  1  is enabled. Provided on the outwards directed lateral edges of synthetic frame  4  in the plane of glass panel  3  is a circumferential groove  6 , preferably T-shaped, for inserting a seal  7 . 
     FIG. 2 diagrammatically illustrates corresponding foaming tool  10  comprising a tool upper section  11  and a tool lower section  12 . Foaming tool  10  can also be rotated through 180° (‘overend’), such that glass panel  3  might then be positioned concavely. As is evident from this, the die cavity on the external circumference of glass panel  3  for forming frame  4  is illustrated here in dotted lines and is formed favorably for flow, so as to ensure good mould filling. This is particularly essential, as glass panel  3  and mountings  5  in this embodiment are fastened by means of the contact surfaces only to frame  4 . The die cavity for forming frame  4  illustrated here in dotted lines is to be sealed beneficially, preferably using a self-separating sealing plate  13  which reliably prevents the synthetic foam entering via one or preferably several injection apertures  14  from overflowing on the upper side of glass panel  3 . The upper side of glass panel  3  is kept clean by this sealing plate  13  during the foaming process, such that there is practically no refinishing work required. 
     It is also evident that secure sealing against ejectors  15  provided further in is possible, ensuring secure filling of the die cavity with extruding of mountings  5 . Further to this, it is evident that tool upper section  11  extends continuously outwards with sealing plate  13 , such that various tool lower sections  12  can be used with same tool upper section  11 . In a production facility this enables the manufacture of different variants of glass sliding rooves  1  with variously positioned mountings  5  using the same plunger-like tool upper section  11 . Simply lifting tool upper section  11  or lowering tool lower section  12  suffices to remove finished glass sliding roof with frame  4 , such that the cycle time is substantially reduced hereby. 
     FIG. 3 illustrates centering device  16  with springs  18  and  19  lying opposite one another in pairs, each of which is here set in to lateral depressions  17  of tool lower section  12 . Said compression springs  18  and  19  are aligned substantially in the plane of flat component  3  and present an identical elastic constant. When glass panel  3  is positioned springs  18  and  19  lie with identical resilience F 1  or F 2  on the lateral edges of the component or glass panel  3 , resulting in automatic centering on account of the spring deflection. This is valid also for components having a varying basic surface or width, so that the centering device can be used for glass panels  3  of varying width. Slight deviations in size can also be compensated for. 
     It is pointed out, however, that a gas spring element or other work storage can be used as centering device or spring  18 ,  19 , whereby such are aligned with the edges somewhat parallel to the principal plane of glass panel  3 . Glass panel  3  is held and centered between springs  18 ,  19  exerting the same force, whereby inserted component  3  is supported on a bearing device  8  which is equipped here with spherical bearing elements  9 . This results in multi-point bearing, whereby bearing device  8  can be designed at the same time and/or partially as ejector  15 , as is illustrated with dashed lines. 
     However, if component  3  or the glass panel is set eccentrically between springs  18  and  19 , as is indicated by measurement ‘x’ between the center line of the tool marked in dot-dash lines and the center line of the component depicted in thin lines, then a stronger force F 2  is exerted on spring  19  until equilibrium of forces F 1 =F 2  by displacing component  3  by measurement ‘x’, resulting in the center lines matching up. It is understood that a second centering device  16  arranged offset by ca. 90° can be provided on the other side edge pair for creating this relative assignment in tool  10 . For reciprocal actuation of centering elements  18 ,  19  on the longitudinal and transverse edges of a component  3  a separate, diagrammatically illustrated retraction device with tension elements  20  can be provided which extend in the manner of pistons to springs  18  and  19 . 
     Respective tension element  20  for retracting springs  18 ,  19 , in particular after insertion or lowering of component  3  into the shape nest of tool lower section  12 , can thereby be formed by compressed air or hydraulic cylinder or screwjack assembly. After tension elements  20  are released and by means of the spring deflection the centering relative assignment is restored automatically by impact from springs  18 ,  19  arranged opposite one another in pairs and having identical elastic constant. Minimal tolerances in the manufacturing of components/glass panels  3  can be well compensated for, so that exact assignment between all components is produced overall. With the preferred embodiment of a glass sliding roof  1  positioning of frame  4  and thus sealing during installation into the vehicle against roof opening  2  (cf. FIG. 1) is improved. However, centering device  16  can also be used for large-surface foaming or encapsulating of components for any synthetic compound elements.