Injection molding machine for molding preforms

An injection molding machine for molding preforms, comprising:

• a) a machine base extending along a horizontal machine axis;
• b) a stationary platen fixed to a platen support portion of the base for supporting a first cavity mold half;
• c) a moving platen supported by the platen support portion and spaced axially apart from the stationary platen, the moving platen for supporting a second cavity mold half;
• d) a center section supported by the platen support portion axially intermediate the stationary and moving platens, the center section having a center section first face for supporting a first core mold half and a center section second face opposite the center section first face for supporting a second core mold half;
• wherein the moving platen and the center section are translatable along the machine axis between a mold-open position, in which the first cavity mold half is spaced axially apart from the first core mold half and the second cavity mold half is spaced axially apart from the second core mold half, and a mold-closed position, in which the first cavity mold half is in engagement with the first core mold half to define a set of first mold cavities for forming a set of molded first preforms, and in which the second cavity mold half is in engagement with the second core mold half to define a set of second mold cavities for forming a set of molded second preforms;
• e) a two-stage first injection unit supported by a first injection unit support portion of the base and positioned behind the stationary platen for injecting a first resin into the first mold cavities through the stationary platen, the first injection unit including a first plasticizing apparatus for plasticizing the first resin and a first plunger apparatus transversely offset from the first plasticizing apparatus for receiving the first resin from the first plasticizing apparatus and forcing the first resin into the first mold cavities through a first nozzle of the second injection unit;
• and
• f) a two-stage second injection unit supported by a second injection unit support portion of the base and positioned behind the moving platen for injecting a second resin into the second mold cavities through the moving platen, the second injection unit including a second plasticizing apparatus for plasticizing the second resin and a second plunger apparatus transversely offset from the second plasticizing apparatus for receiving the second resin from the second plasticizing apparatus and forcing the second resin into the second mold cavities through a second nozzle of the second injection unit, the second injection unit translatable along the machine axis between injection unit retracted and advanced positions to accommodate translation of the moving platen during movement between the mold-open and mold-closed positions.

A method of operating an injection molding machine for molding preforms, comprising:

• a) plasticizing a first resin in a first plasticizing apparatus of a two-stage first injection unit supported behind a stationary platen, and plasticizing a second resin in a second plasticizing apparatus of a two-stage second injection unit supported behind a moving platen;
• b) forcing the first resin from a first shooting pot transversely offset from the first plasticizing apparatus through the stationary platen and into a set of first mold cavities to form a set of molded first preforms, the first mold cavities defined by a first cavity mold half supported by the stationary platen and a first core mold half supported by a center mold section;
• c) forcing the second resin from a second shooting pot transversely offset from the second plasticizing apparatus through the moving platen and into a set of second mold cavities to form a set of molded second preforms, the second mold cavities defined by a second cavity mold half supported by the moving platen and a second core mold half supported by the center mold section opposite the first core mold half;
• and
• d) after step (c), energizing a stroke assembly to open the mold, the stroke assembly including at least one injection unit stroke actuator coupled to the second injection unit and at least one mold stroke actuator coupled to the moving platen and the center section, wherein the at least one injection unit stroke actuator provides at least a portion of an injection unit stroke force required to translate the second injection unit away from the stationary platen when opening the mold, and the at least one mold stroke actuator provides at least a portion of a mold stroke force required to translate the moving platen and the center section away from the stationary platen when opening the mold.

An injection molding machine for molding articles, comprising:

• a) a machine base extending along a horizontal machine axis;
• b) a stationary platen fixed to the base for supporting a first cavity mold half having first recesses for forming a first outer surface of a set of first molded articles;
• c) a moving platen supported by the base for supporting a second cavity mold half having second recesses for forming a second outer surface of a set of second molded articles;
• and
• d) a center section supported by the base axially intermediate the stationary and moving platens, the center section including:
• (i) a center section first face for supporting a first core mold half having first mold core pins for forming a first inner surface of the first molded articles;
• (ii)a center section second face opposite the center section first face for supporting a second core mold half having second mold core pins for forming a second inner surface of the second molded articles;
• and
• (iii) an ejector mechanism disposed between the center section first face and the center section second face;
• wherein the moving platen and the center section are translatable along the machine axis between a mold-closed position and a mold-open position,
• wherein when in the mold-closed position, the first cavity mold half is in engagement with the first core mold half for forming the set of first molded articles, and the second cavity mold half is in engagement with the second core mold half for forming the set of second molded articles;
• and wherein when in the mold-open position, the first cavity mold half is spaced axially apart from the first core mold half and the second cavity mold half is spaced axially apart from the second core mold half, with the first molded articles retained on the first mold core pins and the second molded articles retained on the second mold core pins, the ejector mechanism movable to an ejection position for pushing the first molded articles off the first mold core pins and pushing the second molded articles off the second mold core pins.

A method of operating an injection molding machine configured to mold preforms, comprising:

• a) translating a first take-out plate perpendicular to a machine axis to a first advanced position between a first cavity mold half supported by a stationary platen and a first core mold half supported by a center section, and translating a second take-out plate perpendicular to the machine axis to a second advanced position between a second cavity mold half supported by a moving platen and a second core mold half supported by the center section opposite the first core mold half;
• b) after step (a), transferring a set of molded first preforms from the first core mold half to retained engagement on the first take-out plate, wherein transferring the set of molded first preforms includes activating a first ejector apparatus of the center section, and transferring a set of molded second preforms from the second core mold half to retained engagement on the second take-out plate, wherein transferring the set of molded second preforms includes activating a second ejector apparatus of the center section;
• c) after step (b), translating the first take-out plate to a first retracted position clear of the first cavity mold half and the first core mold half, and translating the second take-out plate to a second retracted position clear of the second cavity mold half and the second core mold half;
• and
• d) after step (c), transferring the first and second preforms from the first and second take-out plates to retained engagement on a transfer shell axially intermediate the first and second take-out plates.