Method and apparatus for sealing a plastic injection mould

摘要

A product is molded by injecting melt into a tool cavity and then following this by injecting pressurized fluid, in particular a gas, between part of the wall and the injected melt. During or after melt injection and during or before injecting the gas the tool cavity(3) is sealed against the outer atmosphere by activating a seal(4) between the tool faces. An Independent claim is made for an the injection molding tool(2) for the process comprising two or more halves and an injector(7) for compressed gas in one wall of the cavity so that a fluid cushion forms between melt and wall. A seal(4) to prevent gas escape is located in at least one tool half. Preferred Features: Activation of the seal(4) is controlled by open and/or closed loop system and is either time, pressure or stroke dependent. Either the melt or compressed fluid may be used as the controlling medium.