| 摘要 |
PURPOSE:To improve boring roundness and cylindricity by arranging a cutter and the ball supported by means of a ball support bar on the rotary axis of the ball support bar on the end of a boring arbor symmetrically in relation to the axis of the boring arbor and balancing the cutting resistance acting on the cutter with the reaction force of a workpiece. CONSTITUTION:A cutter 2 is fitted by a screw 4 to a boring arbor 1, to which a ball support bar 3 is fixed by a screw 5 and supports a ball 6 rotatably on the spherical seat of the end of the ball support bar. The ball 6 is rolled on a face 7 to be finished, and on the other hand, the end of the cutter 2 is abutted on the face 7 of a larger radius by a cutting depth prior to the rolling of the ball 6. The force working on the cutter and heading for the axis of the boring bar acts on the ball 6 with the same load balancing it with the reaction force of a workpiece. Therefore, the boring arbor 1 is never flexed, and cutting conditions are not varied, and the roundness and cylindricity of a bore, and the relative roughness of a finished face are free from being declined.
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