Monotonic cutting machine

Abstract

An apparatus for machining a workpiece such as a crankshaft provides a superior combination of low initial and rebuilding costs, high flexibility in tool changeover and alteration of configuration, yet minimizes floor space and noise level while allowing the combining of several machine operations in a single step. The apparatus also permits the use of optimum cutting speeds, cutting tool feeds, cutting tool composition and cutting tool dimensional tolerances. The apparatus includes a lathe bed to which the crankshaft is mounted and rotated at a variable rate of speed, as well as an arbor disposed parallel to the axis of rotation of the workpiece, rotatable in the same direction at a variable speed. At least one cutter disk is fixedly mounted to the arbor. The disk has a plurality of cutting tools disposed about part but not all of its circumfery, the tools being located at a generally increasing distance from the center of the disk in a stepwise fashion. The circumfery of the disk also includes a second cutout portion between the radially outermost and radially innermost tools. The disk is rotated to bring first the outermost and then the sequentially more inner tools into contact with the spinning workpiece, in order to machine it. The workpiece and disk are each rotated at programmed, varying rates in order to optimally match the tool feed rate and the workpiece surface linear speed for each machining operation, for example, rough cutting, finish cutting, and dimensioning.