CORE BREAKER Russian patent published in 1998 - IPC

FIELD: oil and gas production industry. SUBSTANCE: this relates to drilling equipment and particularly to devices for breaking and holding core during drilling of bore-holes. Core breaker has holder with slots located at different levels, and two groups of levers of different length with turning rolls and cutting faces. Longer levers of them are located in slots of lower level, shorter levers are located in slots of upper level. Angle between front cutting face of long lever and line connecting axis of roll of this lever and its cutting face, and distance in vertical plane between axes of turning rolls are determined according to following expression: γ_l=γ_s+arcsin a/l_s-arcsin a/l_l;, where - angle between front cutting face of long lever and line connecting axis of roll of this lever with its cutting face, deg.; γ_l - distance in vertical plane between axes of turning rolls, mm; γ_s - angle between front cutting face of short lever and line connecting axis of roll of this lever with its cutting face, deg.; a - distance from axis of roll to generating line of core, mm; l_l,l_s - distance from axis of roll to cutting face of long and short levers respectively, mm. Levers are also spring-loaded by resilient members which are installed on turning axles for possible creation of forces which are directly proportional to length of levers. EFFECT: higher efficiency. 1 cl, 3 dwg