Large part injection mold apparatus and process

An injection molding system for performing an injection cycle comprising:

• a heated manifold arranged to distribute an injection fluid to two or more nozzles, each nozzle having an associated gate mated with a mold cavity, each nozzle further having an associated valve pin controllably axially drivable upstream and downstream by an actuator associated with each valve pin between a gate closed position at which flow of the injection fluid is stopped and one or more axial positions upstream of the gate closed position at which flow of the injection fluid through the gate into the mold cavity is enabled;
• and
• a controller arranged to execute instructions that instruct the actuators associated with each valve pin to:
• begin the injection cycle with the valve pins associated with the two or more nozzles in a gate closed position;
• select a first one of the two or more nozzles and controllably drive its associated valve pin from the gate closed position upstream to one or more first axial upstream positions at which a tip end of the valve pin associated with the first one of the two or more nozzles restricts flow of the injection fluid through a first gate associated with the first one of the two or more nozzles to a selected rate of flow that is less than or reduced relative to a maximum rate of flow,
• hold the valve pin associated with the first one of the two or more nozzles in the one or more first axial upstream positions such that injection fluid flows through the first gate downstream through the cavity a preselected distance, wherein the first gate is located at a first position entering the mold cavity;
• controllably drive the valve pin associated with the other of the two or more nozzles upon downstream flow of the injection fluid through the cavity the preselected distance to a selected second axial upstream position of the gated closed position such that injection fluid flows through a second gate associated with the other of the two or more nozzles downstream through the cavity, wherein the second gate is located at a second position entering the cavity downstream of the first position;
• wherein the injection molding system includes an injection fluid property detector that detects, at a downstream detection time, a select property of a flow front of the fluid material at a selected trigger position within the cavity disposed between the first gate and at least one selected downstream gate,
• wherein the controller receives a property signal from the injection fluid property detector indicative of the downstream detection time and includes instructions that instruct the actuator of the nozzle associated with the at least one selected downstream gate to withdraw the valve pin from the gate closed position at a predetermined target time determined by the downstream detection time.

An injection molding system for performing an injection cycle comprising:

• a heated manifold that distributes an injection fluid to two or more nozzles each having an associated gate mated with a mold cavity, each nozzle having an associated valve pin controllably axially drivable upstream and downstream by an actuator associated with each valve pin between a gate closed position at which flow of the injection fluid is stopped and one or more axial positions upstream of the gate closed position at which flow of the injection fluid through the gate into the mold cavity is enabled,
• a controller containing instructions that instruct the actuators associated with each valve pin to:
• begin the injection cycle with the valve pins associated with the two or more nozzles in a gate closed position,
• select a first one of the two or more nozzles and controllably drive its associated valve pin from the gate closed position upstream to one or more first axial upstream positions at which a tip end of the valve pin associated with the first one of the two or more nozzles restricts flow of the injection fluid through a first gate associated with the first one of the two or more nozzles to a selected rate of flow that is less than or reduced relative to a maximum rate of flow,
• hold the valve pin associated with the first one of the two or more nozzles in the one or more first axial upstream positions such that injection fluid flows through the first gate downstream through the cavity a preselected distance,
• wherein the first gate is located at a first position entering the mold cavity,
• controllably drive the valve pin associated with the other of the two or more nozzles upon downstream flow of the injection fluid through the cavity the preselected distance to a selected second axial upstream position of the gated closed position such that injection fluid flows through a second gate associated with other of the two nozzles downstream through the cavity,
• wherein the second gate is located at a second position entering the cavity downstream of the first position,
• wherein the apparatus includes an injection fluid property detector that detects, at a downstream detection time, a select property of a flow front of the fluid material at a selected trigger position within the cavity disposed between the first gate and at least one selected downstream gate,
• wherein the controller receives a property signal from the injection fluid property detector indicative of the downstream detection time and includes instructions that instruct the actuator of the nozzle associated with the at least one selected downstream gate to withdraw the valve pin from the gate closed position at a predetermined target time determined by the downstream detection time,
• wherein the apparatus includes a position sensor that detects, at an actual open gate time, withdrawal of the valve pin from the at least one selected downstream gate,
• the controller receiving a signal from the position sensor indicative of the actual open gate time and including instructions that determine an adjusted instruction time, for use on a subsequent injection cycle, wherein the instructions decrease a time of instruction to the valve pin to open on a subsequent injection cycle by an adjustment time equal to any delay in time between the predetermined target time and the actual open gate time.