Method of making resin-impregnated glass fiber automobile leaf springs

Claim 1

A PROCESS FOR THE PRODUCTION OF RESIN-IMPREGNATED GLASS FIBER LEAF SPRINGS POSSESSING STRENGTH AND FLEXIBILITY CHARACTERISTICS ADAPTING THE SAME FOR AUTOMOTIVE USE WITHOUT REQUIRING EXCESSIVE BULK COMPRISING: (1) WINDING MULTIFILAMENT GLASS STRAND USEFUL IN FILAMENT WINDING PROCESSES ON A FORMING MANDREL SUBJECTED TO AN ELEVATED TEMPERATURE ATMOSPHERE, SAID STRAND BEING MAINTAINED UNDER TENSION AND IMPREGNATED IN ABOUT A 70/30 WEIGHT RATIO OF GLASS TO FINAL RESIN SOLIDS WITH A MIXTURE OF POLYEPOXIDE RESIN AND AMINE CURING AGENT THEREFOR CURABLE TO A "B" STAGE AT SAID ELEVATED TEMPERATURE, SAID WINDING BEING CONTINUED UNTIL THE WINDINGS HAVE A THICKNESS IN EXCESS OF THE FINAL SPRING THICKNESS WHICH IS DESIRED; (2) MAINTAINING THE TENSION ON SAID STRAND UNTIL SAID POLYEPOXIDE RESIN HAS CURED TO SAID "B" STAGE SO THAT SAID STRAND IS UNDER TENSION TENSION IN THE PARTIALLY CURED PRODUCT; AND (3) SUBJECTING SAID PARTIALLY CURED PRODUCT TO AN ELEVATED TEMPERATURE SUFFICIENT TO COMPLETE THE CURE OF SAID POLYEPOXIDE RESIN UNDER A PRESSURE OF AT LEAST 50 P.S.I. TO COMPLETE THE CURE AND REDUCE THE THICKNESS OF SAID PARTIALLY CURED PRODUCT TO THE FINAL DESIRED THICKNESS.