Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ – Composite article making
Patent
1978-07-18
1980-06-17
Anderson, Philip
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
Composite article making
264 403, 264 51, 264328, 264DIG14, 264DIG83, 425162, 425546, 425812, 425817R, B29D 2700
Patent
active
042083680
ABSTRACT:
A method of molding articles of plastic having an expanded plastic cellular core using a closable and sealable mold having a sealed mold cavity and including at least one mold core extending into the cavity, comprises, directing the plastic melt material containing a foaming agent into the mold cavity under pressure so as to form a flow front of the melt which progresses through the cavity and which spreads out in all directions and flows around the mold core and tends to form a pocket of gas in the vicinity of the mold core, and venting the cavity adjacent the core so as to remove gas from any gas pocket which may be formed in the vicinity of the core. The apparatus for carrying out the invention includes a vent line which extends from the cavity in the vicinity of the mold core out of the cavity and which has a control valve for opening the vent line to vent any gas which forms in the cavity and which might tend to form a pocket after the buildup of a pressure in the mold cavity. The vent passage includes at least one capillary-action, gas-pervious passage portion. The vented area advantageously comprises an intermediate space formed between the two mold cores which are connected with a vent line through a very small diameter intermediate space between the core and the hole in the mold cavity containing the vent core. The construction may also advantageously include an ejector plate having pins which penetrate to sealed areas of one of the mold parts and extends into the cavity through an enlarged chamber portion which communicates with the cavity through small diameter capillary-size holes.
REFERENCES:
patent: 3991146 (1976-11-01), Barrie
patent: 4153231 (1979-05-01), Hayakawa et al.
Anderson Philip
Gebruder Buhler AG
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