| 摘要 |
A milling machine is set forth for operation on a pipe string in a cased well to mill the casing. In one embodiment, an inner mandrel having a shoulder is aligned relative to a set of first cutters which are retracted. They are radially extended through slots in an outer body for cutting operations when the pipe string is rotated. Extension is acccomplished by raising pump pressure to move an inner mandrel having a shoulder juxtapositioned relative to the cutters. In an alternate embodiment, the inner mandrel has two shoulders which cooperate with two separate sets of cutters wherein the first set is fully extended and the second set in only partially extended. The coil spring controlling the shoulder for the second set of cutters. The lower end of the tool body includes a constricted outlet orifice for mud flow and an alternate pathway through the inner mandrel and outer body is provided to flush cuttings and chips from the cutters.
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