ROCK CUTTING TOOTH OF DRILLING BIT

rock drilling; applicable in cone drilling bits and crown bits in well drilling with bottom hole washing by means of clay drilling mud, water or blowing of bottom hole with air or gas. SUBSTANCE: rock cutting tooth of drilling bit consists of cylindrical shank and working head. The latter is made in the form of two smoothly conjugated bodies of revolution formed by rotation round tooth symmetry axis of curves convex in shape. Ratio of volumes inside small and large rotation surfaces of tooth head corresponds to internal Vs. s./Vl.s. = 0.04 - 0.25, where Vs.s. is volume inside small surface of rotation located on side of tooth top, cu.mm; Vl.s. is volume inside large surface of rotation located on side of tooth shank, cu.mm. In penetration of such tooth into drilled rock, rate of growth of value of tooth contact area with rock is slower, and volume of rock single cutting by tooth increases and resistance to bit penetration into rock decreases that promotes increase of penetration rate. EFFECT: higher efficiency. 3 cl, 1 dwg