PERCUSSIVE HOLE WIDENER Russian patent published in 1995 - IPC

FIELD: hole drilling. SUBSTANCE: percussive hole widener has body with upper and lower adapters. Accommodated in body is spring- loaded piston and striker. Hinged to body are extending rock cutting member interacting with wedge connected with spring-loaded piston. Installed in lower adapter for axial motion is anvil to which pilot-bit is secured. Widener has additional piston installed above main spring-loaded piston. Wedge is made with shoulders interacting with tail of rock cutting member. During drilling pilot hole, anvil is moved to upper position and blocks rock cutting members from extension. EFFECT: higher efficiency. 1 dwg