The present invention relates generally to metal-working machines employing slide systems and, more particularly, to a machine tool provided with an auxiliary slide used in conjunction with a conventional two-slide system for selectively displacing the cutting tool for machining "off axis" surfaces on a workpiece.
The machine tools or turning machines usually comprise a base of generally T-shaped configuration upon which a pair of slides are mounted for movement in directions normal to one another. The X slide, or cross slide, normally carries the material-removing or cutting tool while the workpiece is mounted on a spindle carried by the Y slide. Slide motions are usually provided by the rotation of precision lead screws driven by electric, pneumatic or hydraulic motors. The path, position, and velocity of the slides may be manually provided or automatically controlled by taped control units.
Conventional machine tools, as briefly described above, are primarily confined to the generation of contours where all cross sections perpendicular to the axis of symmetry are circular. Noncircular or nonaxisymmetric cross sections can be produced by such machine tools by driving one of the two slides synchronously with the spindle rotation to generate a nonaxisymmetrical surface on the workpiece. Such machining has been found to be essentially unattainable with most metals due to relatively high spindle speed requirements which render the synchronization of the slide position with the spindle rotation extremely difficult. Further, conventional X-Y machine-slide systems are relatively massive so that the speed and motion of the slides necessary to provide satisfactory nonaxisymmetric contours cannot be satisfactorily achieved. For example, a parabolic surface can be generated or produced on a workpiece by rotating the workpiece about its axis of symmetry. However, and "off axis" parabolic sector on the parabolic surface is not a figure of revolution about an intersecting axis and cannot be readily machined by "on axis" turning of the workpiece by using previously known machine tools employing conventional X-Y slide systems. The generation of such an "off axis" sector by a conventional machining mechanism requires either that the entire parabolic surface be tracked to obtain only the isolated sector or that a relatively expensive hand-working operation be utilized to form the selected sector. Further, the problems associated with the generation of nonaxisymmetric sectors by conventional methods become increasingly more difficult as the radial spacing of the sector increases from the axis of symmetry.