Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With means between charger and mold to cut off flow of...
Patent
1998-07-17
2000-05-02
Heitbrink, Tim
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With means between charger and mold to cut off flow of...
425563, B29C 4520
Patent
active
060565373
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an injection molding device; in particular, for rubber, caoutchouc or similar materials such as elastomers, thermoset plastics and cross-linkable polymers.
2. Description of the Related Art
EP 0 287 001 A1 relates to a device for the injection molding of materials which comprises a plasticizing unit having an extruder outlet, the device further comprising an injection unit having an injection piston and an injection channel having a discharge opening. The extruder opening of the plasticizing unit is connected to the discharge opening of the injection piston for filling the injection unit. For the injection process, the extruder outlet is separated from the discharge opening and the injection channel is connected to a mold.
DE 91 10 240 U1 describes an injection molding device in which the plasticizing unit is firmly connected to an injection piston through which a feed channel passes leading into the injection cylinder. The end turning away from the injection cylinder is connected to an extruder outlet of the plasticizing unit. The mouth of the feed channel is located at the tip of the free end of the injection piston which tip is conically shaped. The bottom surface of the injection cylinder is formed by an insert and has a conical shape which corresponds to the shape of the free end of the injection piston. A discharge opening in the insert is aligned with the mouth of the feed channel in the injection piston. For filling the injection unit, the discharge opening is closed with a locking bar and material is fed from the plasticizing unit into the injection cylinder via the extruder outlet and the feed channel, the injection piston travelling accordingly. After that, the locking bar is drawn back and the injection unit i s coupled to a mold. Then, the injection piston is entered into the injection cylinder, wherein the check valve in the feed channel is pushed into a closed position and the material is pressed from the injection cylinder into the cavity of the mold. When the injection piston has completely entered the injection cylinder, the orifice of the feed channel is in connection with the discharge opening. After a certain time, the injection unit is separated from the mold by drawing the vulcanized piece out of the injection channel.
BRIEF SUMMARY OF THE INVENTION
The invention is based on the object of producing an injection molding device which is easy to operate. This object is achieved with the features of the claims.
An injection molding device of the invention in particular comprises an injection unit having an injection cylinder and an injection piston travelling therein. The injection cylinder is to be filled via a feed channel arranged in the injection piston and having at least one orifice. The injection cylinder is to be emptied via a discharge opening in the injection cylinder. The orifice of the feed channel is spatially and/or thermally separated from the discharge opening. This constitutes an advantage since the material in the feed channel is not affected by an elevated temperature when the injection unit is coupled to the mold. Particularly, the vulcanization process of the material in the discharge opening can thus be controlled. When the injection unit is decoupled from the mold, the vulcanized material which is sticking to the molded article is drawn from the discharge opening. The discharge opening is thus freed from residues. This surely avoids that material residues partially vulcanized to the molded article are filled into the mold in the next injection step. The injection molding device of the invention thus permits easier operation.
Preferably, the injection piston and the injection cylinder each comprise at least one sealing surface which come into engagement with each other in the inserted position of the injection piston. The advantage of this is that the orifice of the feed channel is sealed against the discharge opening in the injection cylinder when the injection piston is inserted. Th
REFERENCES:
patent: 3295169 (1967-01-01), Moslo
patent: 3398436 (1968-08-01), Nouel
patent: 3918870 (1975-11-01), Tetzlaff
patent: 4286941 (1981-09-01), Gellert
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