IMPROVED DISC CUTTER DESIGN FOR EGRESS BORING MACHINES

DISC CUTTERS USED FOR EGRESS BORING MACHINE APPLICATIONS REQUIRE UNIQUE DESIGN FEATURES. CUTTERS USED ON CONVENTIONAL TUNNEL BORING MACHINES ARE DESIGNED FOR BEST PERFORMANCE AND LIFE CYCLE COSTS WITH CUTTER REPLACEMENT BEING AN ACCEPTABLE FACTOR IN THEIR DESIGN. THIS PROPOSAL ADDRESSES A SYSTEMS ENGINEERING APPROACH TO DEVELOP OPTIMUM DISC CUTTER DESIGNS WITH CUTTER REPLACEMENT BEING UNACCEPTABLE. THE PROGRAM WILL CONCENTRATE ON THREE FUNDAMENTAL OBJECTIVES: (1) INCREASED LOAD CAPACITY; (2) INCREASED WEAR RESISTANCE; AND (3) INCREASED RELIABILITY. PHASE I WILL CONSIST OF DESIGN ANALYSIS AND A TRADE STUDY TO IDENTIFY IMPROVED DISC CUTTER RING GEOMETRIES, ASSEMBLY CONFIGURATIONS AND METALLURGIES. A MATHEMATICAL FINITE ELEMENT MODEL OF A CUTTER RING WILL BE DEVELOPED TO PREDICT STATIC DEFLECTION AND STRESS DISTRIBUTIONS. THIS MODEL WILL BE VERIFIED BY LABORATORY STATIC LOAD TESTS. ADDITIONALLY, A STUDY OF MATERIALS AND PROCESSES WILL BE MADE TO IDENTIFY ALTERNATE RING METALLURGIES AVAILABLE TO ACHIEVE OPTIMUM ABRASION RESISTANCE/TOUGHNESS COMBINATIONS. FINALLY, PHASE I WILL CONCLUDE WITH A SERIES OF DISC CUTTER DESIGN IMPROVEMENTS THAT MEET THE FUNDAMENTAL OBJECTIVES. PHASE II WILL THEN ADDRESS FINAL DESIGN ANALYSIS USING DYNAMIC FINITE ELEMENT MODELING AND FABRICATION OF PROTOTYPES FOR FULL LABORATORY AND FIELD TESTING.