The heating cylinder
A screw may be rotatably mounted in the heating cylinder, and the heating cylinder may be provided with heating means for melting the raw materials.
A first nozzle assembly used in a sheet production extruder according to an exemplary embodiment of the present invention may include: a body having a molten plastic pathway through which the molten plastic passes; a head, one end thereof being connected to the body and the other end thereof being provided with an extruding hole for extruding the molten plastic; a poppet mounted in the body, first and second plastic moving grooves being formed in a length direction thereof at an exterior circumference thereof such that the molten plastic passes through the first and second plastic moving grooves and the gas in the molten plastic is extracted; and a first vent ring exhausting the extracted gas to the exterior of the body, the poppet being inserted in the first vent ring, wherein the molten plastic pathway is only communicated with the second plastic moving groove.
The first plastic moving groove may be opened toward the head and the second plastic moving groove may be blocked toward the head. A vent ring support may be formed at one side portion of the poppet, and a connecting hole communicating the molten plastic pathway with the second plastic moving groove may be formed at the vent ring support. The poppet may include: a shaft; a cone coupled with one end of the shaft and provided with the vent ring support at which the connecting hole communicating the molten plastic pathway with the second plastic moving groove is formed; and a plurality of second vent rings, the shaft being inserted therein and the first and second plastic moving grooves being formed at a single screw extruder circumference thereof.
The first vent ring may include: a first protrusion portion protruded at an exterior circumference of one side of the first vent ring along a length direction thereof; a second protrusion portion protruded at an interior circumference of the one side of the first vent ring along the length direction thereof; and a gas storage area formed between the first protrusion portion and the second protrusion portion.The first protrusion portion may be protruded more than the second protrusion portion by a predetermined length.The first vent ring may be made of sintered metal.
A first gas exhaust hole for exhausting the extracted gas to the exterior of the body may be formed from the interior circumference of the body to the exterior circumference of the body. A second nozzle assembly used in a twin screw extruder according to an exemplary embodiment of the present invention may include: a body having a molten plastic pathway through which the molten plastic passes; A head, one end thereof being connected to the body and the other end thereof being provided with an extruding hole for extruding the molten plastic; a supporting cylinder mounted in the body, a plurality of supporting grooves being formed at the supporting cylinder; a poppet mounted in the supporting cylinder, first and second plastic moving grooves being formed in a length direction thereof at an exterior circumference thereof such that the molten plastic passes through the first and second plastic moving grooves and gas in the molten plastic is extracted; and a vent ring member divided into a plurality of sections, the plurality of sections being inserted respectively in the supporting grooves.