| 摘要 |
PURPOSE:To eliminate roughness due to the rest uncut and realize maintaining smoothness of the outer peripheral face of a rotor by forming one or more than two kerfs parallel with a rotary axis in the outer layer part. expected to be cut by a finishing edge, by means of a spare cutter edge positioned in front of the finishing edge. CONSTITUTION:When a set of broach 56, in a condition of fixing a cocoon-shaped rotor 40, is driven in the direction of an arrow, a kerf 66 is first formed on the outer peripheral face of the rotor 40 by means of a spare cutter edge 60 and, in continuation to this, the outer peripheral face, on which the kerf 66 is formed, is cut by means of a finishing edge 62. Then a finished face 70, with the same sectional form as that of a cutter edge 64, is formed on the outer peripheral face of the rotor 40, and a broad part is processed for finishing with high precision at once. Here, at the time of cutting by the finishing edge 62, the kerf 66 is already formed, and, since chips are divided, starting from the kerf 66, into small pieces with the same breadth as that of the interval between the kerfs 66 and roll individually, resistance to cutting by the finishing edge 62 is reduced to cause a slide 58 to move smoothly. This eliminates generation of exfoliation of the outer layer on the outer peripheral face of the rotor 40, and the surface can be finished smoothly. |
