U.S. Pat. No. 4,114,597 describes the connection of a web plate made of plastic, which serves as a solar collector surface, to a collecting pipe. The collecting pipe consists of an extruded section. The extruded section has a lateral slot into which the front end of the web plate is introduced so that the hollow space inside the web plate ends inside the collecting pipe. The front end of the web plate must be fastened in the slot of the collecting pipe by means of a sealing adhesive, which entails a considerable expenditure of labor. Sealing of the slot of the collecting pipe on the lateral edges of the web plate requires additional measures.
DE-A No. 26 57 468 proposes a plug connection in which a collecting pipe with lateral pipe sockets is introduced into the front side of a web plate so that each of the pipe sockets ends in a hollow chamber of the web plate to sheath and thus seal the hollow chamber with a thick-walled plastic layer. As a result, a great material requirement for the sheathing/sealing compound arises.
According to DE-A No. 30 08 055, a collecting pipe is formed on the front side of a web plate by extrusion. For production of the collecting pipe duct, a core piece is inserted and drawn according to the extrusion process. For the process a special extrusion device is required. The special extrusion device is connected to a transport device for the web plate. Since the drawing of the core piece often causes difficulties, it is proposed in German utility model No. 79 27 236, instead of the core piece, to place a thin-walled collecting pipe with lateral connecting sleeves on the front side of the web plate and then to cover the front end of the web plate and the collecting pipe by an extruded plastic layer.