CLAMPING DEVICE FOR CONNECTING PLASTIC AND METAL ELEMENTS

Abstract: A clamping device for attaching plastic panels against metallic frames/profiles (3), for use in cabins and vehicles, is provided by inserting an end portion of the plastic panel (1) into a preferably conical pocket (2) in the metal profile (3) and locking it in this position by pushing in a cord (4).

Description: Clamping device for connecting plastic and metal elements The invention concerns a clamping device for attaching a plastic panel or plate to a metallic frame or a profile, especially for use in cabins and vehicles. The combination of plastic and metallic structures, such as profiles has been applied widely within many fields. The different properties of the materials create the need to design the technical connection of the two materials in various ways, since account must be taken of the material's specific properties. Attaching plastic to metallic profiles is a special problem area, particularly where modern thermoplastics are employed. The materials are often unsuitable for welding, gluing and screwing or riveting together. The plastic is relatively weak at point loads. In addition, the rest of the materials' properties are different with regard to heat/cold expansions, thus having a substantial influence on the design solution. When building cabins where there is a wish to combine a metallic framework, preferably made of extruded metal profiles, with panels or body sections made of modern thermoplastics, one is faced with considerable challenges with regard to the design round the connecting areas of the metal profiles to the plastic panels. In the case of designs of this kind it is natural to let the extruded profiles form openings in the cabin, such as doors, the ends of windows, etc., thus obtaining a design which can be employed for hinging, screwing on of windows, gluing on of windows, sealing strips etc. The plastic panels or body parts can form three-dimensional basic elements which are then attached to and incorporated with the metal profiles. The object of the present invention is to provide a clamping device which is especially well-suited for use in building such cabins with a combination of plastic plates or panels and metallic framework. This object is achieved with a clamping device which is characterized by that which is presented in the patent claims. The invention will now be explained in more detail by means of embodiments which are presented in the drawings, in which: figure 1 is a first embodiment of the invention, viewed in a purely schematic section, with the inclusion of detail drawings for alternative attaching cord designs, figure 2 is a variant of fig. 1 , with a securing device, figure 3 is a variant of the design in fig. 2, figure 4 is a further embodiment with a locking device, and figure 5 is a variant of fig. 4. The drawings illustrate various alternative embodiments of the clamping device according to the invention in purely schematic form. Fig. 1 hereby illustrates the principal design of the device according to the invention, where the end area of a plastic plate or a plastic panel which may form a body part, has to be passed into a pocket 2 in a metallic profile 3 on a vehicle cabin. The end of the plastic panel 1 is so adapted that it slides into the pocket 2 which will enclose the plastic panel's end edges, thereby forming an attaching area. In order to give the plastic a mechanical connection to the metal profile in these areas, it is designed in a special fashion. Here the edge or end of the plastic panel 1 is inserted in the pocket 2 on the profile. In the illustrated embodiment, the profile is designed with sharp grooves on one side and a more wave-shaped form on the other side, and possibly designed with a slight angle or conical shape in the opening area. After the end of the plastic profile 1 has been inserted in this groove, there is pushed into the pocket or the groove on the inside of the plastic part a partially elastic cord 4, which will cause the plastic panel to be pushed up towards the corrugated plane in the pocket 2, thereby causing the cord 4 to be firmly clamped and pushed down into the grooved/curved shapes in the edge of the pocket. Since the wire 4 is elastically designed with an elasticity which may be firmer and more resilient than the plastic material, the plastic material will creep slightly up in the corrugated surface, providing a physical bond between the metal and the plastic material in the shear direction. Alternatively, the end of the plastic profile is designed with an upwardly- directed groove or bead on its outer edge, as illustrated in fig. 2. This bead is pushed up in a groove formed in the inner area of the pocket 2 of the metal profile, thereby ensuring that the panel is unable to slide out of the pocket. With such a design it is not necessary to have a sharp-edged grooving of the end lateral surface of the pocket. An alternative to this design is illustrated in fig. 3 which presents a "reverse" design to that in fig. 2, the bead being provided in the wall of the pocket, while the end of the plastic panel has a groove. In order to ensure that the elastic cord 4 does not loosen or fall out during use over a period of time, when the elasticity in the cord 4 may be reduced and its resilience deteriorate, a locking profile 5 can be employed as illustrated in fig. 4. This locking profile 5 can also be made with an upwardly-directed edge 6 which can cover a profiled end part 7 of the plastic panel 1 , which end part 7 is inserted in the pocket 2, as illustrated in fig. 5. By this means it will be possible to ensure that the plastic panel 1 cannot slide out of the pocket 2, thereby losing its position and the connection with the metal profile 3. The locking cord 4 can be made by extrusion with a circular section, figure of eight section or wedge-shaped with a curved/wavy surface, which latches on to the grooves/curves in the profile pocket. These alternatives are illustrated as detail section drawings in fig. 1. The locking cord may also have a twisted structure. A special feature of the invention is based on the fact that the plastic's outside 8 is used at all times as reference surface against the metallic profile 3, thereby ensuring that a controlled level is obtained for the outsides of the plastic panel and the profile element. This can be a problem particularly where the plastic panels/body parts are of unequal thickness. In the present invention this is carried out by the cord which is pushed into the slightly conically shaped pocket being locked in such a manner that it pushes the plastic edge's outer side against the top of the metal profile independently of the plastic panel's thickness and unevenness. The present invention also contributes to a point-free attaching device which provides good distribution of the clamping forces and offers the possibility for thermal expansion and movement of the materials in relation to each other without major strains and destruction of the panels. By using a continuous cord an uninterrupted clamping can be obtained along the entire length of the profile pocket into which the end portion of the plastic panel is inserted. Uneven thickness of the plastic panel's end section in this direction will be absorbed by the cord and the cord will also act as a sealing strip.

Claims: PATENT CLAIMS 1. A clamping device for attaching plastic panels to metallic frames/profiles, especially for use in cabins and vehicles, characterized in that the plastic panel's end portion is inserted into a preferably conical pocket in the metal profile, and is locked in this position by a pressed-in cord. 2. A device according to claim 1 , characterized in that the pocket in the metallic profile has approximately sharp ribs on the side which faces the plastic panel's outside. 3. A device according to claim 1 or 2, characterized in that the pocket in the metallic profile has an approximately wavy/corrugated surface for locking the cord at the side of the pocket which faces the plastic panel's inside. 4. A device according to one of the claims 1-3, characterized in that the cord is elastic in the transverse direction. 5. A device according to one of the claims 1-4, characterized in that a projecting edge or bead in the profile pocket engages with the plastic panel's outside or a notch in the outside, or that the plastic plate's outside is designed with a bead which engages with a groove in the profile pocket's lateral surface. 6. A device according to one of the claims 1-5, characterized in that the cord is locked/secured by a profile which pushes it into the pocket and which is attached to the metal profile. 7. A device according to one of the claims 1-6, characterized in that the profile for locking and securing the cord has an outwardly-directed profile part, which is locked against the plastic panel's rear edge by the lowered arrangement of the plastic panel in connection with the attachment against the main profile.

Inventors: BROWN DAVID, BROWN, DAVID
Applicants: BROWN DAVID, PIVCO AS, BROWN, DAVID
Application year: 1998
Main classification: B62D27
IPC codes: B62D27, B62D29, F16B2, F16B5