This invention pertains to a forming mold for postforming of an shaped polymer cord that is extruded onto an object.
It is known that vehicle windows are equipped with a frame or frame-shaped elements by extruding directly onto a glass a shaped cord that is made of an extrudable polymer in a corresponding manner. Likewise, other plate-like objects such as, for example, doors can be equipped with a frame-shaped sealing joint. Generally, however, the shaped cord extruded onto the object has to be postformed in certain places, for instance, in the transition zone between the beginning and end of a closed frame. Such postforming may also be necessary or advantageous in the area of the corners of a shaped frame, particularly in the case of sharp corners.
Extrudable polymers that are used for the above-mentioned purposes include both reaction systems, for example, polyurethane systems that harden under the action of moisture, and thermoplastic systems. In the case of reaction systems, the postforming may be done right after the extrusion operation before the extruded polymer cord hardens. Such a postforming process and the appropriate compression molds for implementing it are described in documents U.S. Pat. No. 5,519,979 and German patent no. DE-G-U1 90 11 573. In the case of a reaction system, the postforming may also be done after the shaped cord hardens. A corresponding process and an appropriate mold for implementing it, comprising a forming mold, are the objects of documents U.S. Pat. No. 5,057,265.
Devices that comprise a forming mold for the postforming of the transition zone of a thermoplastic polymer frame that is extruded onto a glass are described in documents WO 95/35193 and WO 96/19339.
In all of the known devices for postforming, the forming surface of the forming mold is adapted over its entire length to the geometry of the extruded shaped cord. This means that, for example, in the case of an extruded frame on a flat glass, the shaped forming surface is rectilinear.
When postforming is done with the aid of the known forming mold, it may happen that joint lines, which are caused by the edges at the end faces of the forming mold, are visible at the transition points between the postformed section length and the lengths of the initial extruded sections. Such visible joint lines show up in particular when the dimensions, in terms of height, of the shaped extruded cord or the shape and thickness of the objects vary slightly within the limits of the given tolerances.