Extrusion-pressing of high-impact, fuel tank blow-moldings, employs controlled blowing nozzle, core and separation strategy, followed by flange welding of shells formed

摘要

A tubular preform (3) of defined length, is extruded from a perpendicular or horizontal adjustable nozzle (1). This is a round blowing nozzle with wall thickness control. Guides (4) spread the preform. A cutter (6) forms two curtains which are led over an internal core (11). Mold halves (7, 9) advance to form two shells with flange surrounds, by pressing. In an alternative, curtains are not formed, but the preform (3) is cut during pressing, along a plane of separation.. Mold stamps trim the shells; ejectors then extract them. The shells are welded together. An independent claim is included for a machine carrying out the corresponding method. Preferred features: Before pressing, finished parts (15) are inlaid in reception recesses (16) of the core (11). They are welded precisely into place by the pressing process. During pressing, flanges are heated to welding temperature only on the core side. Remaining core and molding surfaces are cooled via bores. Following pressing, extraction and removal from the core, the shells are held firmly in the mold e.g. by suction. When they approach again, the shells are welded together by the sensible heat of their flanges, forming the finished container. When making vehicle tanks especially, an inner tank is laid into the lower shell. It comprises preferably two light, thin, deep-drawn sheet metal shells, connected diffusion-tight together. The sheet has a low tear strength and a precisely-located intentional rupture region, protecting against unacceptable internal pressure. The inner tank is fitted with parts such as a filling pipe, pump, level gauge and residue container. Connections to the inner tank are further detailed. Shell flange interior sealing faces, and tank openings, are metal-plated with an environmentally-acceptable, flexurally-resistant, sealed metal layer. A separate round section seal is included. The flange includes an O-ring groove, covered by plating. A suitable seal resisting effects of fuel, and diffusion, is inlaid. In an alternative, the seam is joined by immersion flow-soldering, during welding of the shells. Further variants based on the foregoing principles are described.