Method for molding propeller blades

Claim 1

IN THE DIE MOLDING OF SLOPING ECHELON CONTOURED OBJECTS HAVING UNIDIRECTIONAL FILIFORM REINFORCEMENTS, THE METHOD OF AVOIDING INITIAL TENSIONS IN THE PRODUCT PRODUCED DURING MOLDING WHICH CONSISTS IN FIRST APPLYING TO ONE FACE OF THE DIE CAVITY A FIRST SMALL QUANTITY OF POLYMERIZABLE ISOTROPIC MOLDING POWDER, THEN APPLYING A STACK OF PARTRIALLY POLYMERIZED RESINOUS FLAT PLATES WHICH CONTAIN SUBSTSANTIALLY PARALLEL FILIFORM REINFORCEMENTS EXTENDING IN THE DIRECTION OF APPLICAATION OF MAXIMUM TENSION TO THE FINISHED PRODUCT IN USE, SAID STACK BEING ECHELON-TRIMMED TO APPROXIMATELY FILL THE DIE CAVITY AND FORMING AN ECHELON, APPLYING A SECOND SMALL QUANTITY THE SAME ISOTROPIC MOLDING POWDER TO THE SIDE OF SAID STACK OPPOSITE TO THE SIDE THEREOF IN CONTACT WITH SAID FIRST SMALL QUANTITY OF ISOTROPIC MOLDING POWDER, THE QUANTITY OF SAID ISOTROPIC MOLDIN POWDER SO APPLIED BEING SUFFICIENT TO FILL ALL THE VOIDS OF SAID ECHELON BETWEEN THE FACETS OF SAID ECHELON TRIMMED STACK AND THE WALLS OF SAID DIE CAVITY, AND APPLYING TO SAID MOLD CAVITY SIMULTANEOUSLY CONTAINING SAID STACK AND SAID POWDER, HEAT AND PRESSURE SUFFICIENT TO COMPLETE POLYMERIZATION OF SAID STACK AND SAID TWO QUANTITIES OF POWDER AS AN INTEGRAL MOLDED ARTICLE, WHEREBY THE PRODUCT HAS A CONTINUOUS, SMOOTH, ISOTROPIC OUTER SURFACE, AND SUBSTANTIALLY NO INITIAL TENSION PRODUCED DURING MOLDING.