DRILLING TOOL Russian patent published in 1998 - IPC

FIELD: bore-hole drilling equipment. SUBSTANCE: this is used for drilling with coring by means of removable rock-crushing tool. Drilling tool has outer pipe with serrated end face, removable core receiver, and expandable sector-type drilling bit which is suspended from core receiver on bush with holders. Drilling bit has protrusions for interaction with serrated end face of outer pipe. Sectors are provided with interacting protrusions in the form of tooth engagement members for operating with serrated end face of outer pipe. Serrations of end face and tooth engagement members are made with incline so as to prevent displacement of sectors in direction towards longitudinal axis of rotation of tool during its operation. Aforesaid embodiment of tool increases recovery of core and enhances reliability in operation of drilling tool. EFFECT: higher efficiency. 2 dwg