Process and apparatus for molding thermosetting material

Claim 2

IN AN INJECTION MOLDING PROCESS FOR MASS PRODUCTION OF ARTICLES FROM THERMOSETTING MATERIAL WHEREIN THE SAME CYCLE OF OPERATION IS REPEATED OVER AND OVER AGAIN WITHOUT PURGING OF THE EQUIPMENT AND WHEREIN THE THERMOSETTING MATERIAL IS ADVANCED IN INCREMENTS THROUGH A CHARGING CYLINDER TOWARD A DISCHARGE NOZZLE AND IS PROGRESSIVELY HEATED IN SAID CYLINDER TO A TEMPERATURE BELOW ITS CURING TEMPERATURE TO FACILITATE PLASTIC FLOW, EACH CYCLE COMPRISING IN SERIATIM THE STEPS OF (1) APPLYING A HIGH PRESSURE TO THE MATERIAL IN SAID CYLINDER TO FORCE IT THROUGH SAID NOZZLE INTO THE INTERNAL CAVITY OF A MOLD THAT IS HEATED TO A TEMPERATURE SUFFICIENT TO CURE SAID MATERIAL, (2) MAINTAINING THE PRESSURE UNTIL THE MATERIAL IN SAID MOLD PASSAGES AND AT THE DISCHARGE END OF SAID NOZZLE HAS CURED TO THE NON-PLASTIC STATE, AND (3) REMOVING THE NON-PLASTIC THERMOSET MATERIAL FROM SAID MOLD CAVITY BEFORE THE NEXT SUCCESSIVE CYCLE, THE IMPROVEMENT WHICH COMPRISES THE STEPS OF MAINTAINING SAID CYLINDER IN A FIXED POSITION AWAY FROM THE HEATED MOLD TO REDUCE THE TRANSFER OF HEAT FROM SAID MOLD TO SAID CYLINDER, PROVIDING THE NOZZLE WITH A LONG TAPERED AXIAL PASSAGEWAY WHICH GRADUALLY INCREASES IN DIAMETER FROM ITS INLET END TO ITS OUTLET END, APPLYING HIGH PRESSURE TO THE MATERIAL AND HOLDING THE NOZZLE IN CONTACT WITH THE HEATED MOLD DURING EACH CYCLE FOR A PERIOD OF TIME SUCH THAT THE POINT OF TRANSITION OF THE THERMOSETTING MATERIAL FROM ITS PLASTIC TO ITS NON-PLASTIC STATE IS NEAR THE INLET END OF THE NOZZLE WHEN SUCH CONTACT IS BROKEN, MOVING SAID NOZZLE AXIALLY RELATIVE TO SAID CYLINDER IN ACCORDANCE WITH THE PRESSURE APPLIED TO THE THERMOSETTING MATERIAL TO ADVANCE THE NOZZLE AXIALLY AGAINST THE INLET OF THE HEATED MOLD WHEN A HIGH PRESSURE IS APPLIED TO SAID MATERIAL; TO RETRACT THE NOZZLE OUT OF CONTACT WITH THE HEATED MOLD WHEN THE PRESSURE IS REDUCED WHEREBY THE HEAT TRANSFER FROM THE HEATED MOLDS IS SO MINIMIZED THAT THE MATERIAL REMAINING AT THE INNER END OF SAID PASSAGEWAY IN MAINTAINED IN THE UNCURED STATE; SERVING THE CURED FROM THE UNCURED PORTION OF MATERIAL IN SAID PASSAGEWAY AND INJECTING IN THE NEXT MOLDING CYCLE.

Claim 3

IN AN AUTOMATIC INJECTION MOLDING MACHINE, A MOLD HAVING AN INTERNAL MOLD CAVITY FOR RECEIVING THERMOSETTING MATERIAL AND MEANS FOR HEATING THE MOLD TO A TEMPERATURE SUFFICIENT TO CURE SAID MATERIAL, A MOLD INLET IN THE HEATED MOLD IN COMMUNICATION WITH SAID MOLD CAVITY, AND APPARATUS SPACED FROM THE HEATED MOLD FOR PERIODICALLY FEEDING THE THERMOSETTING MATERIAL INTO SAID MOLD CAVITY INCLUDING AN AXIALLY ELONGATED CHARGING CYLINDER HAVING HEATING MEANS INCLUDING AXIALLY SPACD WATER JACKETS AND MEANS FOR RAPIDLY CIRCULATING LIQUID THROUGH SAID JACKETS FOR PROGRESSIVELY HEATING THE THERMOSETTING MATERIAL AS IT FLOWS FROM THE INLET END TO THE DISCHARGE END OF SAID CYLINDER TO A TEMPERATURE BELOW BUT APPROACHING THE CURING TEMPERATURE AND FOR MAINTAINING THE TEMPERATURE OF THE MATERIAL IN THE CHARGING CHAMBER OF SAID CYLINDER BELOW SAID CURING TEMPERATURE, A CHARGING PISTON MOUNTED FOR RECIPROCATION IN SAID CYLINDER NEAR THE INLET END THEREOF, REMOVABLE MEANS FOR CLOSING THE DISCHARGE END OF SAID CYLINDER COMPRISING A HOLLOW PLUG DETACHABLY CONNECTED TO SAID CYLINDER AND A SEALING RING CLAMPED BETWEEN THE END OF SAID PLUG AND SAID CYLINDER TO PREVENT LEAKAGE AT THE OUTER PERIPHERY OF SAID PLUG, SAID PLUG HAVING AN AXIAL BORE AND COUNTERBORE SUBSTANTIALLY IN ALIGNMENT WITH SAID MOLD INLET, SAID COUNTERBORE BEING LOCATED AT THE END PORTION OF SAID PLUG NEAREST SAID CHARGING CHAMBER, AN AXIALLY ELONGATED TUBULAR CONDUIT WITH A LENGTH MATERIALLY GREATER THAN THAT OF SAID PLUG HAVING A SHANK PORTION OF REDUCED DIAMETER MOUNTED FOR LIMITED RECIPROCATION IN SAID BORE FROM A RETRACTED POSITION OUT OF CONTACT WITH SAID MOLD TO AN ADVANCED OPERATING POSITION AGAINST SAID MOLD INLET WHEREIN THE THERMOSETTING MATERIAL IS DIRECTED TO SAID MOLD CAVITY, MEANS FOR PREVENTING LEAKAGE OF SAID MATERIAL BETWEEN SAID MOLD INLET AND THE END OF SAID CONDUIT WHEN THE CONDUIT IS HELD IN SAID OPERATING POSITION, SAID TUBULAR CONDUIT HAVING AN ENLARGED SELF-SEALING PISTON AT ITS INLET END MOUNTED FOR RECIPROCATION IN SAID COUNTERBORE TO EFFECT MOVEMENT OF SAID CONDUIT BETWEEN SAID OPERATING POSITION AND SAID RETRACTED POSITION IN RESPONSE TO MOVEMENT OF SAID CHARGING PISTON, SAID SELF-SEALING PISTON HAVING PERIPHERAL SEALING MEANS COMPRISING AXIALLY SPACED GROOVES, MEANS FOR RETRACTING SAID CHARGING PISTON AND FOR SIMULTANEOUSLY RETRACTING SAID SELF-SEALING PISTON TO RETRACT THE CONDUIT TO STOP THE CONDUCTION OF HEAT DIRECTLY FROM THE MOLD THROUGH SAID CONDUIT TO SAID CYLINDER, WHEREBY THE PLASTIC THERMOSETTING MATERIAL REMAINING AT THE INLET END OF SAID CONDUIT MAY BE FED INTO THE MOLD CAVITY IN THE NEXT CYCLE OF OPERATION WITHOUT PURGING OF THE APPARATUS.

Claim 4

IN AN AUTOMATIC INJECTION MOLDING MACHINE, A MOLD HAVING AN INTERNAL MOLD CAVITY FOR RECEIVING THERMOSETTING MATERIAL AND MEANS FOR HEATING THE MOLD TO A TEMPERATURE SUFFICIENT TO CURE SAID MATERIAL, A MOLD INLET IN THE HEATED MOLD IN COMMUNICATION WITH SAID MOLD CAVITY, AND APPARATUS SPACED FROM THE HEATED MOLD FOR PERIODICALLY FEEDING THE THERMOSETTING MATERIAL INTO SAID MOLD CAVITY INCLUDING AN AXIALLY ELONGATED CHARGING CYLINDER HAVING HEATING MEANS INCLUDING AXIALLY SPACD WATER JACKETS AND MEANS FOR RAPIDLY CIRCULATING LIQUID THROUGH SAID JACKETS FOR PROGRESSIVELY HEATING THE THERMOSETTING MATERIAL AS IT FLOWS FROM THE INLET END TO THE DISCHARGE END OF SAID CYLINDER TO A TEMPERATURE BELOW BUT APPROACHING THE CURING TEMPERATURE AND FOR MAINTAINING THE TEMPERATURE OF THE MATERIAL IN THE CHARGING CHAMBER OF SAID CYLINDER BELOW SAID CURING TEMPERATURE, A CHARGING PISTON MOUNTED FOR RECIPROCATION IN SAID CYLINDER NEAR THE INLET END THEREOF, REMOVABLE MEANS FOR CLOSING THE DISCHARGE END OF SAID CYLINDER COMPRISING A HOLLOW PLUG DETACHABLY CONNECTED TO SAID CYLINDER AND A SEALING RING CLAMPED BETWEEN THE END OF SAID PLUG AND SAID CYLINDER TO PREVENT LEAKAGE AT THE OUTER PERIPHERY OF SAID PLUG, SAID PLUG HAVING AN AXIAL BORE AND COUNTERBORE SUBSTANTIALLY IN ALIGNMENT WITH SAID MOLD INLET, SAID COUNTERBORE BEING LOCATED AT THE END PORTION OF SAID PLUG NEAREST SAID CHARGING CHAMBER, AN AXIALLY ELONGATED TUBULAR CONDUIT WITH A LENGTH MATERIALLY GREATER THAN THAT OF SAID PLUG HAVING A SHANK PORTION OF REDUCED DIAMETER MOUNTED FOR LIMITED RECIPROCATION IN SAID BORE FROM A RETRACTED POSITION OUT OF CONTACT WITH SAID MOLD TO AN ADVANCED OPERATING POSITION AGAINST SAID MOLD INLET WHEREIN THE THERMOSETTING MATERIAL IS DIRECTED TO SAID MOLD CAVITY, MEANS FOR PREVENTING LEAKAGE OF SAID MATERIAL BETWEEN SAID MOLD INLET AND THE END OF SAID CONDUIT WHEN THE CONDUIT IS HELD IN SAID OPERATING POSITION, SAID TUBULAR CONDUIT HAVING AN ENLARGED SELF-SEALING PISTON AT ITS INLET END MOUNTED FOR RECIPROCATION IN SAID COUNTERBORE TO EFFECT MOVEMENT OF SAID CONDUIT BETWEEN SAID OPERATING POSITION AND SAID RETRACTED POSITION IN RESPONSE TO MOVEMENT OF SAID CHARGING PISTON, SAID SELF-SEALING PISTON HAVING PERIPHERAL SEALING MEANS COMPRISING AXIALLY SPACED GROOVES, MEANS FOR RETRACTING SAID CHARGING PISTON AND FOR SIMULTANEOUSLY RETRACTING SAID SELF-SEALING PISTON TO RETRACT THE CONDUIT TO STOP THE CONDUCTION OF HEAT DIRECTLY FROM THE MOLD THROUGH SAID CONDUIT TO SAID CYLINDER, WHEREBY THE PLASTIC THERMOSETTING MATERIAL REMAINING AT THE INLET END OF SAID CONDUIT MAY BE FED INTO THE MOLD CAVITY IN THE NEXT CYCLE OF OPERATION WITHOUT PURGING OF THE APPARATUS.