| 摘要 |
<p>A rotary cone drill bit (20) for forming a borehole (24) having a one-piece bit body (40) with a lower portion (46) having a convex exterior surface (48) and an upper portion (42) adapted for connection to a drill string (22). A number of support arms (70) are preferably attached to pockets (54) formed in the bit body (40) and depend therefrom. Each support arm (70) has an inside surface (76) with a spindle (82) connected thereto and an outer surface (80). Each spindle (82) projects generally downwardly and inwardly with respect to the longitudinal axis (72) of the associated support arm (70) and the central axis (50) of the bit body (40). A number of cone cutter assemblies (100) equal to the number of support arms (70) are mounted respectively on each of the spindles (82).</p> |
