Method of shell molding

Claim 1

IN A PROCESS OF PRODUCING A LAMINATED HOLLOW SHELL CORE FROM SAND MIXED WITH A T HERMOSETTING RESIN WHICH INCLUDES THE STEPS OF FILLING A HEATED CORE BOX WITH A LOOSE MIXTURE OF SAND AND THERMOSETTING RESIN AND THEN PERMITTING SUBSTANTIALLY ALL OF THE SAND RESIN MIXTURE TO FLOW FROM THE PATTERN TO LEAVE A THIN LAYER OF PARTIALLY CURED SAND RESIN MIXTURE AT LEAST A PORTION OF WHICH IS SUPPORTED AGAINST GRAVITY ONLY BY ITS OWN RIGIDITY AND ADHERRENCE TO THE WALL OF THE CORE BOX, THE IMPROVEMENT COMPRISING PERMITTING THE RESIN PORTION OF THE SAND RESIN MIXTURE ADJACENT THE HEATED METAL SURFACE TO CURE FOR A TIME NOT IN EXCESS OF FIVE SECONDS AND ONLY SUFFICIENTLY TO PRODUCE A THIN SELF-SUPPORTING LAMINA OF SAND RESIN MIXTURE, REMOVING THE EXCESS OF THE NON-ADHERING LOOSE SAND RESIN MIXITURE, PERMITTING THE RESIN IN THE SAND RESIN LAMINATION SO PRODUCED TO CURE FURTHER, AGAIN FILLING THE HEATED CORE BOX WITH A LOOSE SAND RESIN MIXTURE, MAINTAINING THIS LOOSE SAND RESIN MIXTURE IN CONTACT WITH THE THIN LAMINATION UNTIL THE DESIRED THICKNESS OF CORE HAS BEEN PRODUCED, REMOVING THE EXCESS LOOSE AND RESIN MIXTURE AND CURING THE LAMINATED CORE SO FORMED.