DURABLE DRILL BIT FOR DRILLING BLASTHOLES IN HARD ROCK (OPTIONS) Russian patent published in 2021 - IPC E21B10/18 E21B10/50 

FIELD: mining.

SUBSTANCE: group of inventions relates to rock bits for drilling blastholes. The bit contains: a bit body having a connecting device made at its upper end, multiple legs located below, a dome made between the legs, and a channel made through the connecting device and the dome; multiple ‘skirts’, each ‘skirt’ covering a gap formed between adjacent legs, and each ‘skirt’ is attached to the edges of the adjacent legs; multiple conical roller cutters, with each rotating roller cutter being fixed freely rotating on the corresponding bearing shaft of the corresponding leg; a series of calibrating cutting tools attached to each conical roller cutter; a series of internal cutting tools attached to each conical roller cutter; one or more front cutting elements attached to each conical roller cutter; and a central nozzle attached to the channel. The central nozzle contains: a throttle diaphragm containing many windows or a single window with many branching sections, with each window or each branching section directed to the joint between adjacent conical roller cutters, and a backflow shutdown valve designed to open in response to drilling fluid being pumped down into the channel and close to block the flow up through the channel. Each cutter is a plug-in pin. The inner and outer surfaces of each ‘skirt’ extend straight through the corresponding gap, or each ‘skirt’ is arched and follows a curved path across the corresponding gap so that the bottom view of the hard rock bit shows the area taken by the ‘skirts’ and calibrating working surfaces of the conical roller cutters resembling a circle.

EFFECT: technical result consists in increased durability of the rock bit.

16 cl, 6 dwg