SINGLE-ROLLER BIT Russian patent published in 1999 - IPC

FIELD: rock drilling equipment. SUBSTANCE: single-roller cutter bit has body with washing passage, and rolling cutter installed on journal which is inclined relative to longitudinal axis of symmetry of body. Rolling cutter is made asymmetrical relative to axis of journal and cylindrical relative to bit axis. Bit is provided with mechanism for fixing rolling cutter in transport position of bit. Mechanism includes cylinder connected with body which accommodates stop and spring-biased circular piston. Pivotally connected to circular piston is detent for fixing rolling cutter in transport position of bit located in washing passage of body. Lower end of detent enters recess made in recess of rolling cutter. Stop and piston create through-passage of lateral cross-section area which is larger than difference between lateral cross-section areas of washing passage and detent. Due to this difference, pressure differential between aforesaid passages is created in washing fluid during operation of bit which removes detent from engagement with rolling cutter. On completion of drilling large-diameter bore-hole, at stopping of bit washing and removing axial thrust from bit, spring shifts piston and detent connected to it towards rolling cutter of bit. In result their engagement takes place allowing for free lifting of tool from bore-hole. Aforesaid embodiment of single-roller bit enhances its operating performance. EFFECT: higher efficiency. 3 cl, 3 dwg