ROLLER-TYPE DRILLING BIT Russian patent published in 1998 - IPC

FIELD: drilling machinery and equipment. SUBSTANCE: this relates to drilling deep bore-holes of large diameter by means of drilling bits with roller-type rock-crushing tools. Roller-type drilling bit has lugs 1 and journals 2. Mounted on journals 2 by means of bearings 3 are rolling cutters 4. Rolling cutters 4 are of spherical-taper shape. Relation of taper part 5 and spherical part 6 of rolling cutter 4 is determined from following expression: R_c/R_d = 0.55-0.75, where R_c - distance from center of bit to point of conjugation of taper part and spherical part of rolling cutter, mm; R_d - radius of drilling bit, mm. Provided on rolling cutter 4 are rock-crushing members in the form of milled teeth or hard-alloy teeth 9. Provided on relieving cone 10 are facing cutters 11. Facing cutters 11 can be arranged in one or several rows. Located between milled teeth are additional hard-alloy teeth. Facing cutters 11 by their working parts protrude beyond surface of rolling cutters 4. In working position, facing cutters 11 can be arranged in circumference of bore-hole which is formed by peripheral teeth or they can slightly protrude beyond aforesaid circumference. Spherical parts 6 of rolling cutters 4 conjugate with relieving surfaces 10. Application of aforesaid roller-type drilling bit allows for obtaining bore-hole with stable smooth walls of cylindrical form. Effective diameter of bore-hole is increased. Service life of roller-type drilling bit is prolonged. EFFECT: higher efficiency. 4 cl, 4 dwg