Gas injection apparatus for gas assisted injection molding system

A gas injection apparatus for use with a gas assisted injection molding system, the gas injection apparatus including means defining a bore communicating upstream with a source of gas and downstream with a mold cavity, and a pin positioned in the bore to define a gas flow passage therebetween for movement of gas from the gas source to the mold cavity, characterized in that:

• the bore includes a first upstream portion and a second downstream portion adjoining the first portion;
• the pin includes a first upstream portion positioned in the first bore portion and a second downstream portion adjoining the first pin portion and positioned in the second bore portion;
• the pin has a substantially uniform diameter throughout the first and second pin portions generally corresponding to the diameter of the second bore portion;
• and
• the periphery of the second pin portion is radially recessed at at least one circumferential location around the periphery of the second pin portion to define an axial linear passageway between the second pin portion and the second bore portion.

For use with a gas assisted injection molding system, a gas injection apparatus including means defining a bore communicating upstream with a source of gas and downstream with a mold cavity:

• the bore including a first upstream portion and a second downstream portion adjoining the first upstream portion and having a lesser diameter than the first portion;
• the pin including a first upstream portion positioned in the first bore portion and a second downstream portion adjoining the first portion and positioned in the second bore portion;
• the pin having a substantially uniform diameter throughout said first and second pin portions generally corresponding to the diameter of said second bore portion, whereby to define a close fit between the second bore portion and the second pin portion and define a clearance between the first bore portion and the first pin portion;
• and
• the periphery of said second pin portion being radially recessed at at least one circumferential location around the periphery of the second pin portion to define an axial linear passageway between the second pin portion and the second bore portion communicating at an upstream end thereof with said clearance.

For use with a gas assisted injection molding system, a gas injection apparatus for delivering gas from a source of gas to a mold cavity, the injection apparatus including:

• a sleeve positioned in a mold bore and defining a sleeve bore communicating upstream with the source of gas and downstream with the mold cavity;
• and
• a pin positioned in the sleeve bore and coacting with the sleeve bore to define passage means therebetween for movement of gas from the gas source to the mold cavity;
• the sleeve bore including a first upstream portion, a second portion downstream of and adjoining the first portion and having a lesser diameter than the first portion, and a third portion downstream of and adjoining the second portion and having the same diameter as the second portion;
• the pin including a first upstream portion positioned in the first upstream bore position, a second portion adjoining the first upstream portion and positioned in the second bore portion, and a third portion adjoining the second portion and positioned in the third bore portion;
• the pin having a substantially uniform diameter throughout said first and second pin portions generally corresponding to the diameter of said second bore portion, whereby to define a close fit between the second bore portion and the second pin portion and define a clearance between the first bore portion and the first pin portion, and having a lesser diameter in said third portion, whereby to define an annular axial passage between the third pin portion and the third bore portion;
• the periphery of said second pin portion being radially recessed at at least one circumferential location around the periphery of the second pin portion to define an axial linear passageway between the second pin portion and the second bore portion communicating at an upstream end thereof with said clearance and communicating at a downstream end thereof with said annular passage.

A gas injection apparatus for use with a gas assisted injection molding system, the gas injection apparatus including a sleeve and a pin coacting with the sleeve to define a gas flow passage for communicating a source of gas with a mold cavity, characterized in that;

• the sleeve includes upstream and downstream bore portions coacting with the pin;
• the pin includes an upstream portion positioned in the upstream bore portion and a downstream pin portion positioned in the downstream bore portion;
• the upstream bore portion has a diameter generally corresponding to the diameter of the upstream pin portion;
• the downstream bore portion has a diameter greater than the diameter of the downstream pin portion to define an annular axial passage between the downstream pin portion and the downstream bore portion;
• the annular interface of the upstream bore portion and the upstream pin portion includes a radial recess at at least one circumferential location around the interface defining a linear axial passage extending axially through the interface and communicating with the annular axial passage;
• and
• the generally corresponding diameters of the upstream bore portion and the upstream pin portion define a close fit which is operative to substantially preclude radial migration of said upstream pin portion with respect to said upstream bore portion so as to maintain a substantially uniform radial clearance in the annular axial passage to allow free flow of gas through said annular axial passage into said cavity while resisting entry or resin into the annular axial passage.

A gas injection apparatus for use with a gas assisted injection molding system, the gas injection apparatus including means defining a bore communicating upstream with a source of gas and downstream with a mold cavity, and a pin positioned in the bore and coacting with the bore to define a gas flow passage therebetween for movement of gas from the gas source to the mold cavity, characterized in that:

• the bore includes a downstream bore portion and an upstream bore portion adjoining the downstream portion;
• the pin includes a downstream pin portion positioned in the downstream bore portion and an upstream pin portion adjoining the downstream pin portion and positioned in the upstream bore portion;
• the downstream bore portion has a diameter greater than the downstream pin portion so as to define an annular axial passage between the downstream bore portion and the downstream pin portion;
• the upstream bore portion has a diameter generally corresponding to the diameter of the upstream pin portion;
• the annular interface of the upstream bore portion and the upstream pin portion includes a radial recess at at least one circumferential location around the annular interface defining a linear axial passage extending axially through the annular interface and communicating with the annular axial passage;
• the generally corresponding diameters of the upstream bore portion and the upstream pin portion define a close fit to maintain the downstream pin portion centered in the downstream bore portion so as to maintain a substantially uniform radial clearance dimension throughout the circumferential extent of the annular axial passage;
• and
• an annular distribution groove is defined proximate the juncture of the upstream and downstream bore portions communicating upstream with the linear axial passage and downstream with the annular axial passage and operative to distribute gases flowing linearly through the linear passage circumferentially uniformly to the annular axial passage.

A gas injection apparatus for use with a gas assisted injection molding system, the gas injection apparatus including means defining a bore communicating upstream with a source of gas and downstream with a mold cavity, and a pin positioned in the bore and coacting with the bore to define a gas flow passage therebetween for movement of gas from the gas source to the mold cavity, characterized in that:

• the bore includes a downstream bore portion and an upstream bore portion adjoining the downstream portion;
• the pin includes a downstream pin portion positioned in the downstream bore portion and an upstream pin portion adjoining the downstream pin portion and positioned in the upstream bore portion;
• the downstream bore portion has a diameter greater than the downstream pin portion so as to define an annular axial passage between the downstream bore portion and the downstream pin portion;
• the upstream bore portion has a diameter generally corresponding to the diameter of the upstream pin portion and substantially equal to the diameter of the downstream bore portion;
• the annular interface of the upstream bore portion and the upstream pin portion includes a radial recess at at least one circumferential location around the annular interface defining a linear axial passage extending axially through the annular interface and communicating with the annular axial passage;
• and
• the generally corresponding diameters of the upstream bore portion and the upstream pin portion define a close fit to maintain the downstream pin portion centered in the downstream bore portion so as to maintain a substantially uniform radial clearance dimension throughout the circumferential extent of the annular axial passage.

A gas injection apparatus for use with a gas assisted injection molding system, the gas injection apparatus including means defining a bore communicating upstream with a source of gas and downstream with a mold cavity, and a pin positioned in the bore and coacting with the bore to define a gas flow passage therebetween for movement of gas from the gas source to the mold cavity, characterized in that:

• the bore includes a downstream bore portion and an upstream bore portion adjoining the downstream portion;
• the pin includes a downstream pin portion positioned in the downstream bore portion and an upstream pin portion adjoining the downstream pin portion, positioned in the upstream bore portion, and having a diameter substantially equal to the diameter of the downstream pin portion;
• the downstream bore portion has a diameter greater than the downstream pin portion so as to define an annular axial passage between the downstream bore portion and the downstream pin portion;
• the upstream bore portion has a diameter generally corresponding to the diameter of the upstream pin portion;
• the annular interface of the upstream bore portion and the upstream pin portion includes a radial recess at at least one circumferential location around the annular interface defining a linear axial passage extending axially through the annular interface and communicating with the annular axial passage;
• and
• the generally corresponding diameters of the upstream bore portion and the upstream pin portion define a close fit to maintain the downstream pin portion centered in the downstream bore portion so as to maintain a substantially uniform radial clearance dimension throughout the circumferential extent of the annular axial passage.

A gas injection apparatus for use with a gas assisted injection molding system, the gas injection apparatus including means defining a bore communicating upstream with a source of gas and downstream with a mold cavity, and a pin positioned in the bore and coacting with the bore to define a gas flow passage therebetween for movement of gas from the gas source to the mold cavity, characterized in that:

• the bore includes a downstream bore portion and an upstream bore portion adjoining the downstream portion;
• the pin includes a downstream pin portion positioned in the downstream bore portion and an upstream pin portion adjoining the downstream pin portion and positioned in the upstream bore portion;
• the downstream bore portion has a diameter greater than the downstream pin portion so as to define an annular axial passage between the downstream bore portion and the downstream pin portion;
• the upstream bore portion has a diameter generally corresponding to the diameter of the upstream pin portion;
• the generally corresponding diameters of the upstream bore portion and the upstream pin portion define a close fit to maintain the downstream pin portion centered in the downstream bore portion so as to maintain a substantially uniform radial clearance dimension throughout the circumferential extent of the annular axial passage;
• and
• the periphery of the upstream pin portion is configured in cross-section to define a plurality of axially extending circumferentially spaced recesses interconnected by a plurality of full diameter axially extending land portion, the recesses coacting with the upstream bore portion to define a plurality of circumferentially spaced linear axial passages therebetween communicating upstream with the source of gas and downstream with the annular axial passage.

A gas injection apparatus for use with a gas assisted injection molding system, the gas injection apparatus including a sleeve and a pin coacting with the sleeve to define a gas flow passage for communicating a source of gas with a mold cavity, characterized in that;

• the sleeve includes upstream and downstream bore portions coacting with the pin;
• the pin includes an upstream portion positioned in the upstream bore portion and a downstream pin portion positioned in the downstream bore portion;
• the upstream bore portion has a diameter generally corresponding to the diameter of the upstream pin portion;
• the downstream bore portion has a diameter greater than the diameter of the downstream pin portion to define an annular axial passage between the downstream pin portion and the downstream bore portion;
• the annular interface of the upstream bore portion and the upstream pin portion includes a radial recess at at least one circumferential location around the interface defining a linear axial passage extending axially through the interface and communicating with the annular axial passage;
• the generally corresponding diameters of the upstream bore portion and the upstream pin portion define a close fit so as to maintain a substantially uniform radial clearance in the annular axial passage;
• and
• an annular distribution groove is defined between the upstream and downstream bore portions to uniformly distribute the flow of gas from the linear axial passage circumferentially into the annular axial passage.