73408222
Jan 4, 1983
BLADE TYPE DRILLING BITS COMPRISING A SERIES OF STEPS WHICH ARE TIPPED WEAR-RESISTANT CUTTING ELEMENTS OF NATURAL AND/OR CYNTHETIC DIAMOND, INCLUDING POLY- CRYSTALLINE SUPERABRASIVE COMPOSITE MATERIALS AND COMBINATIONS THEREOF, FOR USE IN ROTARY AND TURBINE DRILLING SOFT THROUGH HARD FOUNDATIONS
Machinery