Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Producing multilayer work or article
Patent
1992-08-05
1994-05-03
Timm, Catherine
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Producing multilayer work or article
425503, 425525, 425535, B29C 4920
Patent
active
053085736
DESCRIPTION:
BRIEF SUMMARY
INDUSTRIAL FIELD OF UTILIZATION
The present invention relates to a method of molding a fuel tank having baffle plates and, more specifically, to a method of molding a fuel tank by the blow-molding method and, at the same time, mounting baffle plates on the inner surface of the fuel tank as a unitary structure.
PRIOR ART
Plastic fuel tanks such as automotive fuel tanks have been provided with baffle plates on the inside thereof in order to improve mechanical strength, and to prevent unpleasant sound that is generated when the fuel pitches and rolls in the tank while the vehicle is running and to stabilize the internal capacity of the tank.
A conventional method of molding a fuel tank with baffle plates consists of using a metal mold having convex portions that correspond to the plates, and effecting the blow-molding while arranging in the metal mold the parison that is formed by extrusion-molding or injection-molding a thermoplastic resin.
According to the above method, however, the root portions of the baffle plates tend to lose thickness, limitation is imposed on the size of the baffle plates, and technological difficulty is involved in molding two pieces of baffle plates simultaneously.
GIST OF THE INVENTION
The object of the present invention therefore is to provide a method of molding a fuel tank having baffle plates, which effectively solves the above-mentioned problems inherent in the prior art.
According to the present invention, there is provided a method of molding a fuel tank comprising inserting a blow-pin in a molten parison of a thermoplastic resin from the lower side thereof, said blow-pin having a plurality of grooves formed therein downwardly extending from the tip of said blow-pin and having different lengths relative to each other, mounting a plurality of pre-molded baffle plates on said blow-pin via the plurality of grooves, closing the split metal molds under this condition, feeding a pressurized fluid thereto, and melt-adhering the baffle plates onto the inner surface of the fuel tank while said fuel tank is being molded.
This is, according to the present invention, it is allowed to provide a plurality of, for example, two pieces of baffle plates in the fuel tank simultaneously with the molding of the fuel tank without resulting in the formation of very thin portions.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side sectional view of a baffle plate molded article used in the present invention;
FIG. 2 is a plan view of the baffle plate molded article used in the present invention;
FIG. 3 is a diagram illustrating another baffle plate molded article used in the present invention;
FIG. 4 is a side sectional view illustrating a blow-pin used in the present invention;
FIG. 5 is a plan view of the blow-pin that is used in the present invention;
FIG. 6 is a diagram showing the step of blow-molding according to the present invention; and
FIG. 7 is a diagram showing a fuel tank produced according to the present invention.
PREFERRED EMBODIMENTS OF THE INVENTION
In the present invention, examples of the resin material for making baffle plates and fuel tank include any thermosetting resins that can be blow-molded such as polyolefin resins, e.g., low-, medium- and high-density polyethylenes, a polypropylene, an ethylene-.alpha.-olefin copolymer, a thermoplastic polyester, a polyamide resin, etc. Among them, a polyolefin resin is preferably used. Moreover, the thermoplastic resins must exhibit not only resistance against environmentally caused stress and cracks (ESCR property) for light oils that are now chiefly used as fuels and methanol that has been studied to be used as a fuel in the future, but also gas barrier property, impact resistance, heat resistance and weatherability. Among the polyolefin resins, the high-density polyethylene is preferably used from the standpoint of such properties. As the baffle plates, in particular, there can be preferably used the high-density polyethylene having a melt flow rate (MFR) of 0.01 to 10 g/10 min. and particularly 0.1 to 10 g/min. under th
REFERENCES:
patent: 3919373 (1975-11-01), Kormendi
Mitsui Petrochemical Industries Ltd.
Timm Catherine
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