SMALL DISC CUTTERS, AND DRILL BITS, CUTTERHEADS, AND TUNNEL BORING MACHINES EMPLOYING SUCH ROLLING DISC CUTTERS

摘要

Small diameter rotary drill bits (30) with detachable pedestal mounted rollingdisc cutters (36), the bit having a plurality of longitudinaledge mounting slots (38) located at preselected angularly spaced apartlocations. A set of peripheral pedestal mounts (34) each having amounting portion sized is mounted in its preselected mounting slot. In oneembodiment, the longitudinally extending slots further comprisea wedge shaped edge portion (54), and the pedestal mounts have a complimentaryangularly shaped portion (54P). The pedestal mounts(34) each include, at the lower reaches thereof at least one small diametersingle cutting edge rolling disc cutter (36). The rolling disccutters are affixed at individually preselected radially spaced apartlocations with respect to a central longitudinal axis forming the centerof rotation of the rotary drill bit. Also, each of the rolling disc cutters ismounted at a preselected angle delta with respect to the centrallongitudinal axis forming the center of rotation of the rotary drill bit.Also, the rolling disc cutters are preferably detachably affixed to thepedestal mounts.