Processes for producing electrical coils insulated with mica and synthetic resins and the products thereof

Claim 1

IN THE METHOD OF PREPARING A WINDING FOR AN ELECTRICAL MACHINE, THE WINDING COMPRISING A SLOT PORTION AND ENDS WHICH ENDS ARE TO BE CONNECTED TO OTHER ENDS, THE STEPS COMPRISING WRAPPING THE ENTIRE LENGTH OF THE WINDING CONDUCTOR WITH A PLURALITY OF LAYERS OF A COMPOSITE TAPE, THE TAPE COMPRISING ESSENTIALLY TWO SUPERIMPOSED SHEETS OF PLIABLE MATERIAL, A LAYER OF MICA FLAKES DISPOSED BETWEEN THE TWO SUPERIMPOSED SHEETS, AND A LIQUID BINDER APPLIED TO THE LAYER OF MICA FLAKES AND THE SURFACES OF THE SHEETS OF PLIABLE MATERIAL IN CONTACT WITH THE MICA FLAKES, THE BINDER COMPOSED OF A LIQUID, RELATIVELY NON-VOLATILE, RESINOUS POLYMER OF A VISCOSITY OF BETWEEN 25 AND 10,000 POISES AT 25* C., THE LIQUID BINDER NOT EXCEEDING 70% OF THE WEIGHT OF THE COMPOSITION TAPE, APPLYING A FINAL WRAPPING OF A TAPE CONSISTING OF GLASS FIBERS, HEATING THE WINDING WITH THE APPLIED LAYERS OF TAPES TO A TEMPERATURE NOT EXCEEDING 175* C., COOLING THE WRAPPED WINDING TO A TEMPEATURE NOT SUBSTANTIALLY IN EXCESS OF 50* C., APPLYING A VACUUM TO THE COOLED CONDUCTOR TO WITHDRAW VOLATILES THEREFROM, THE HEATING AND VACUUM NOT REMOVING MORE THAN A MINOR PROPORTION OF THE LIQUID RESINOUS POLYMER BINDER FROM THE WRAPPING, VACUUM IMPREGNATING THE COOLED WINDING WITH A COMPLETELY REACTIVE POLYMERIZABLE COMPOSITION COMPRISING A MONOMERIC COMPOUND HAVING THE GROUP H2C=K<, THE POLYMERIZABLE COMPOSITION BEING COMPATIBLE WITH THE LIQUID RESINOUS BINDER WHEREBY THE LIUQID POLYMERIZABLE COMPOSITION READILY PENETRATES THROUGH THE COMPOSITE TAPE WRAPPING TO THE CONDUCTOR AND FILLS ALL THE INTERSTICES AND SPACES IN THE WRAPPED WINDING, APPLYING OVER THE TAPE OF GLASS FIBERS A RELATIVELY LIQUID-TIGHT LAYER OF A FLEXIBLE TAPE OF A RESINOUS MATERIAL IMPERVIOUS TO AND INSOLUBLE IN THE POLYMERIZABLE COMPOSITIONS, PLACING THE WRAPPED, IMPREGNATED WINDING IN A CONFINING MOLD TO FORM THE WRAPPINGS TO DESIRED CROSS-SECTIONAL SHAPE AND TO SHAPE THE SLOT-SECTION PORTION OF THE WINDING, PLACING A COMPRESSED ELASTIC CONFINING MEANS ALONG THE ENDS OF THE WINDING, SHAPED THE ENDS OF THE WINDING TO THE DESIRED CONFIGURATION, HEATING THE CONFINED WINDING TO POLYMERIZE THE COMPLETELY REACTIVE POLYMERIZABLE COMPOSITION TO A SOLID RESIN, REMOVING THE CURED WINDING FROM THE CONFINING MOLD, REMOVING THE COMPRESSED ELASTIC CONFINING MEANS FROM THE WINDING ENDS, AND REMOVING THE LIQUID TIGHT LAYER OR FLEXIBLE TAPE.