DEVICE FOR DIRECTIONAL CRACK FORMING IN BOREHOLE (VARIANTS) Russian patent published in 2006 - IPC E21C37/12 E21C37/04 

FIELD: mining engineering, particularly to create cracks in boreholes for rock breaking into blocks having necessary shape and dimensions, for crystalline raw material and building stone mining, for rock and solid material breakage in predetermined plane.

SUBSTANCE: device comprises body with working tools. One body end is installed in tube in which longitudinal and transversal cuts are formed. The longitudinal and transversal cuts are connected one to another. Transversal cuts are enclosed by the body. The working tools are rod ends passing through longitudinal cuts and extending outside the tube. Device in accordance with the second embodiment comprises cup put on device body and provided with longitudinal and transversal cuts connected one to another. The cup also has central orifice. Transversal cuts are enclosed by the body. The working tools are rod ends passing through longitudinal cuts and extending outside the cup. The body is provided with stepped thinned section passing through central cup orifice. Bar end is connected to stepped section end. Spring is installed between the bar and cup bottom.

EFFECT: increased operational efficiency due to decreased risk of working body penetration in cracks, which are out of predetermined rock breakage plane, as well as simplified working tool structure.

13 cl, 3 dwg