| 摘要 |
A cutter for a downhole milling or cutting tool and a tool incorporating the blade has a longitudinal axis (97) about which the tool is rotatable. The tool may have a plurality of circumferentially disposed blades which are either fixed or radially movable to perform a cutting operation. Each of the cutters has a blade (100) having a cutting surface (17) which is formed by a plurality of cutting elements (20). Each of the cutting elements has a plurality of protruding cutting edges (3) each of which are longitudinally spaced from one another and interspaced from one another by a recess portion (1) so that in use swarf moves upwardly from one of the cutting edges along the recess portion and is subsequently broken off. By providing such relatively closely spaced cutting edges generally C-shaped swarf cuttings are produced and "birdnesting" is substantially reduced or eliminated. The cutting elements each have a cutting surface (41) which presents a negative radial rake angle in the range 1-10<o> and a lead attack angle in the range 1-15<o>. |
