Arrangement for introducing a gas into the cavity of an injection mold for producing a hollow plastic body

Claim 1

An arrangement for introducing a metered volume of gas into a cavity filled with a melt of plastic and defined by an injection mold for producing a hollow plastic body, the injection mold having an injection channel for introducing the molten plastic into the cavity and the arrangement comprising: a gas-injection nozzle assembly having a housing mounted in the mold and a member displaceably mounted in said housing so as to be movable between a first position and a second position located in spaced relationship to the injection channel; said housing and said member conjointly defining a forward end portion of said nozzle assembly facing into said cavity at a region of said cavity spaced from the injection channel; gas-conducting means formed in said forward end portion for conducting the gas into said cavity when said member is in said second position; said gas-conducting means defining a gas-discharge opening for discharging the gas into said cavity; projecting means for freely projecting said gas-discharge opening approximately into the center of said region for discharging the gas when said member is in said second position and while said melt is injected into said cavity; said projecting means including a ram arranged on said member and guide means for defining a guide channel for accommodating said ram therein; said gas-conducting means including a first gas-conducting channel formed in said housing and a second gas-conducting channel formed in said ram for communicating with said first gas-conducting channel when said member is in said second position; said ram defining a longitudinal axis and having a front end portion for extending into said cavity when said member is in said second position; said front end portion having a closed forward sharp tipped end face for penetrating through said melt of plastic when said member moves into said second position and said ram having a transverse channel formed in said front end portion so as to extend transverse to said axis; and, said transverse channel being part of said second gas-conducting channel and defining said gas-discharge opening; and, said member being mounted in said housing so as to cause said gas-discharge opening to be within said guide channel when said member is in said first position thereby closing off said opening.