| 摘要 |
PROBLEM TO BE SOLVED: To provide an improved thrust bearing. SOLUTION: An improved rotary cone bit includes a drill bit main body having two or more leg portions extending from one end of the drill bit main body. A united portion of the leg portions is formed of a bearing pin which is extended inside the drill bit main body in an axial direction and includes a peripheral basement formed in the vicinity of a pin distal end. Then, a cutter cone including an inner basement formed in order to be mated to the peripheral basement of each bearing pin is rotatively set at each bearing pin. The thrust bearing having a plurality of cylindrical rollers located at a retainer wheel is located between the peripheral basement of the bearing pin and the inner basement of the cutter cone. The thrust bearing transmits a force generated on the cutter cone by conventional drilling operation to the distal end of the bearing pin. COPYRIGHT: (C)2003,JPO
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