Method for making hollow plastic rotational casting and for removing casting from mold

Claim 1

THE METHOD OF MAKING A HOLLOW CASTING WITH GENERALLY HEMISPHERICAL SHAFT-SUPPORTING ENDS AND UNIFORM WALL THICKNESS OVER ALL OUTER CURVED ZONES FROM A WATERSOLUBLE HEAT-MELTABLE MATERIAL WHICH HARDENS AT NORMAL TEMPERATURES, AS FOR A WINDING MANDREL, WHICH COMPRISES: PROVIDING A METAL MOLD WITH A CYLINDRICAL MID-PORTION AND GENERALLY HEMISPHERICAL END CAPS HAVING END OPENINGS AND EQUATORIAL TRANSVERSE JOINTS WITH THE CYLINDRICAL MID-PORTION, THE MOLD HAVING WALLS OF UNIFORM THICKNESS, INCLUDING THE JOINTS, OVER ALL OUTER CURVED AREAS, PROVIDING BOLTED-ON POLE PIECES CLOSING THE ENDS OF THE CAPS, THE BOTTOM END POLE PIECE HAVING A HOLE-DEFINING CORE PLUG AND THE TOP END POLE PIECE HAVING AN INTERIOR FILL AND VENT SPOUT OF A DIAMETER TO PERMIT QUICK FILLING WITH LIQUID MATERIAL BUT PERVENTING OUTFLOW OF LIQUID WHEN THE MOLD IS TURNED ON THE SIDE AND HAVING A LENGTH SUCH THAT LIQUID CANNOT FLOW OUT WHEN THE SPOUT IS DISPOSED LOWERMOST BUT SHORT ENOUGH TO PREVENT LIQUID FROM ENGAGING THE SPOUT WHEN IT IS DISPOSED UPPERMOST, ASSEMBLING THE MOLD PARTS READY TO RECEIVE MOLTEN LIQUID MATERIAL, HEATING THE ASSEMBLED MOLD EVENLY IN A CLOSED MUFFLE HEATER UP TO A TEMPERATURE SOMEWHAT ABOVE THE TEMPERATURE OF THE MOLTEN LIQUID TO BE POURED INTO IT, MELTING THE MATERIAL IN A CLOSED FURNACE UNDER PROTECTED CONDITIONS, SECURING THE HEATED MOLD WITH THE FILL SPOUT END UPPERMOST IN A CAGE OF A GYRATORY GIMBAL TURNING MACHINE WITH HEAT INSULATION AGAINST ALL METAL CONTACT WITH THE MOLD AND WITH MOST OF THE MOLD EXPOSED TO THE AIR, ADJUSTING THE MOLD TO BE AT APPROXIMATELY THE SAME TEMPERATURE AS THE MOLTEN LIQUID IN THE FURNACE, POURING FROM THE FURNACE INTO THE MOLD THROUGH ITS SPOUT THE CORRECT AMOUNT OF MOLTEN LIQUID TO BE FORMED INTO THE HOLLOW CASTING, COOLING THE MOLD TO SOLIDIFY SAID MATERIAL IN A COATING ON THE INTERIOR WALLS OF THE MOLD, LEAVING THE FILL AND VENT SPOUT OPEN FOR VENTING WHILE THE MATERIAL SOLIDIFIES, IMMEDIATELY AFTER POURING BEGINNING THE TURNING OF THE CAGE TO FLOW THE LIQUID EVENLY OVER THE INTERIOR MOLD SURFACES, AND CONTINUING THE TURNING MOVEMENT UNTIL ALL OF THE MATERIAL HARDENS TO FORM A HOLLOW CASTING IN THE MOLD, REMOVING THE MOLD FROM THE CAGE, REMOVING THE BOTTOM END POLE PIECE AND BREAKING A HOLE THROUGH MATERIAL WHICH FORMED ON THE END OF THE CORE PLUG, INSERTING A ROD THROUGH THE HOLE IN THE BOTTOM END AND RAPPING THE FILL SPOUT TO BREAK OFF THE MATERIAL WHICH HARDENED THEREON, UNFASTENING THE BOTTOM END CAP AND REMOVING IT FROM THE HOLLOW CASTING, UNFASTENING AND PULLING OFF THE TOP END POLE PIECE, UNFASTENING THE TOP END CAP AND REMOVING IT FROM THE HOLLOW CASTING, COVERING THE MOLD EXTERIORLY WITH HEAT INSULATING MATERIAL AND BLOWING AIR THROUGH THE INTERIOR OF THE HOLLOW CASTING TO SHRINK ITS DIAMETER, AND REMOVING THE HOLLOW CASTING FROM THE MOLD BY RELATIVE ENDWISE MOVEMENT BETWEEN THE HOLLOW CASTING AND THE MOLD.

Claim 2

THE METHOD OF MAKING A HOLLOW CASTING WITH GENERALLY HEMISPHERICAL SHAFT-SUPPORTING ENDS AND UNIFORM WALL THICKNESS OVER ALL OUTER CURVED ZONES FROM A WATERSOLUBLE HEAT-MELTABLE MATERIAL WHICH HARDENS AT NORMAL TEMPERATURES, AS FOR A WINDING MANDREL, WHICH COMPRISES: PROVIDING A METAL MOLD WITH A CYLINDRICAL MID-PORTION AND GENERALLY HEMISPHERICAL END CAPS HAVING END OPENINGS AND EQUATORIAL TRANSVERSE JOINTS WITH THE CYLINDRICAL MID-PORTION, THE MOLD HAVING WALLS OF UNIFORM THICKNESS, INCLUDING THE JOINTS, OVER ALL OUTER CURVED AREAS, PROVIDING BOLTED-ON POLE PIECES CLOSING THE ENDS OF THE CAPS, THE BOTTOM END POLE PIECE HAVING A HOLE-DEFINING CORE PLUG AND THE TOP END POLE PIECE HAVING AN INTERIOR FILL AND VENT SPOUT OF A DIAMETER TO PERMIT QUICK FILLING WITH LIQUID MATERIAL BUT PERVENTING OUTFLOW OF LIQUID WHEN THE MOLD IS TURNED ON THE SIDE AND HAVING A LENGTH SUCH THAT LIQUID CANNOT FLOW OUT WHEN THE SPOUT IS DISPOSED LOWERMOST BUT SHORT ENOUGH TO PREVENT LIQUID FROM ENGAGING THE SPOUT WHEN IT IS DISPOSED UPPERMOST, ASSEMBLING THE MOLD PARTS READY TO RECEIVE MOLTEN LIQUID MATERIAL, HEATING THE ASSEMBLED MOLD EVENLY IN A CLOSED MUFFLE HEATER UP TO A TEMPERATURE SOMEWHAT ABOVE THE TEMPERATURE OF THE MOLTEN LIQUID TO BE POURED INTO IT, MELTING THE MATERIAL IN A CLOSED FURNACE UNDER PROTECTED CONDITIONS, SECURING THE HEATED MOLD WITH THE FILL SPOUT END UPPERMOST IN A CAGE OF A GYRATORY GIMBAL TURNING MACHINE WITH HEAT INSULATION AGAINST ALL METAL CONTACT WITH THE MOLD AND WITH MOST OF THE MOLD EXPOSED TO THE AIR, ADJUSTING THE MOLD TO BE AT APPROXIMATELY THE SAME TEMPERATURE AS THE MOLTEN LIQUID IN THE FURNACE, POURING FROM THE FURNACE INTO THE MOLD THROUGH ITS SPOUT THE CORRECT AMOUNT OF MOLTEN LIQUID TO BE FORMED INTO THE HOLLOW CASTING, COOLING THE MOLD TO SOLIDIFY SAID MATERIAL IN A COATING ON THE INTERIOR WALLS OF THE MOLD, LEAVING THE FILL AND VENT SPOUT OPEN FOR VENTING WHILE THE MATERIAL SOLIDIFIES, IMMEDIATELY AFTER POURING BEGINNING THE TURNING OF THE CAGE TO FLOW THE LIQUID EVENLY OVER THE INTERIOR MOLD SURFACES, AND CONTINUING THE TURNING MOVEMENT UNTIL ALL OF THE MATERIAL HARDENS TO FORM A HOLLOW CASTING IN THE MOLD, REMOVING THE MOLD FROM THE CAGE, REMOVING THE BOTTOM END POLE PIECE AND BREAKING A HOLE THROUGH MATERIAL WHICH FORMED ON THE END OF THE CORE PLUG, INSERTING A ROD THROUGH THE HOLE IN THE BOTTOM END AND RAPPING THE FILL SPOUT TO BREAK OFF THE MATERIAL WHICH HARDENED THEREON, UNFASTENING THE BOTTOM END CAP AND REMOVING IT FROM THE HOLLOW CASTING, UNFASTENING AND PULLING OFF THE TOP END POLE PIECE, UNFASTENING THE TOP END CAP AND REMOVING IT FROM THE HOLLOW CASTING, COVERING THE MOLD EXTERIORLY WITH HEAT INSULATING MATERIAL AND BLOWING AIR THROUGH THE INTERIOR OF THE HOLLOW CASTING TO SHRINK ITS DIAMETER, AND REMOVING THE HOLLOW CASTING FROM THE MOLD BY RELATIVE ENDWISE MOVEMENT BETWEEN THE HOLLOW CASTING AND THE MOLD.