International Classification:
B21K 502
Abstract:
A method for assembling earth drill bits starts with a hollow shank body with a hollow pin with API regulation threads, for connection to a drill pipe, extending from one side, and hollow nozzle legs extending from the other side cast as a one piece investment casting. Separate leg members are rough formed and machined to shape having a bit body portion, depending leg, and inwardly and downwardly extending bearing journal. Conical roller cutters are supported for rotation on the bearing journals. A passage formed through the bit body portion and depending leg provides for lubrication of the conical roller cutters. The conical roller cutters are secured in place by a liquid lock formed by filling a cavity between the interior of the cutter cone and the journal bearing which is filled with liquid and sealed. The bit body portions fit together and are welded to form a sub-assembly with an end wall for the hollow pin and side recesses receiving the hollow nozzle legs (containing interchangeable hard metal nozzle members) and are welded peripherally to the open end of the hollow shank body. A ceramic or hard-metal insert at the open end of the hollow shank body is secured in place when the shank body and bit body sub assembly are welded together and protects against abrasion from drilling fluid flowing through the hollow pin.
