| 摘要 |
FIELD: mining industry, particularly for drilling blastholes in open-cast mines and underground mines and for drilling test wells. ^ SUBSTANCE: roller bit formed in accordance with the first embodiment comprises body with coupling and scavenge ports, pivot shafts, support cutters with milled teeth or reinforced hard-alloy teeth. Cutters have working surface part of truncated spherical shape, pivot cutter shafts with truncated spherical surfaces installed under equal acute angles to vertical bit axis and inclined towards well wall. The acute angle is chosen from drilling conditions. Pivot shafts are installed on body by means of replaceable sections. Pivot shaft areas of replaceable sections are inclined to horizontal axis at an angle equal to angle of pivot shaft inclination to vertical bit axis. Ratio between bit diameter and larger cutter diameter D/dc is 2.17-2.2. Roller bit formed in accordance with the second embodiment comprises body with coupling and scavenge ports, pivot shafts, support cutters with milled teeth or reinforced hard-alloy teeth. Cutters have working surface part of truncated spherical shape. For mining and geological conditions where body durability is comparable with that of cutter bearing and cutting structures and for bits with diameter D>160 mm pivot shafts of all cutters having truncated spherical surfaces are welded to pivot shaft area of the body and extends at equal acute angles to vertical bit axis towards well wall. The acute angle is chosen from drilling conditions. Pivot shaft areas of the body are inclined to horizontal axis at an angle equal to angle of pivot shaft inclination to vertical bit axis. Ratio between bit diameter and larger cutter diameter D/dc is 2.17-2.4. ^ EFFECT: increased operational reliability and extended field of efficient application thereof, possibility to cut hard and very hard rock due to rolling of spherical cutters and carrying out crushing action by the cutters and due to applying increased axial force to bit, improved efficiency or face cleaning from drill cuttings and optimization of operating conditions of drilling operation. ^ 2 cl, 3 dwg |
