Numerical control system for center lathes

Claim 1

Numerical control apparatus for controlling the machining of a workpiece rotated by a mandril of a lathe, the machining of said workpiece requiring the tool of the lathe to move along a multisegment path with respect to said workpiece, said apparatus comprising: means for reading from an input record medium the coordinates of the end point of the next segment of said path with respect to the axis of the workpiece, the datum specifying the programmed divergence of the transverse position of the cutting edge of a programmed tool being used with respect to the cutting edge of a reference tool, the cutting rate for said programmed tool, and the axial feed rate of said programmed tool; settable means for adjusting said datum according to the tool being used with respect to the programmed tool; means receptive of said coordinates and said adjusted datum from said reading means for generating artificial coordinates of said end point inclusive of said divergence of the cutting edge of the used tool; means for interpolating the artificial coordinates of the beginning point and the artificial coordinates of the end point of said next segment and the axial feed rate of said tool to continually specify the proper instantaneous distance of the tool from said axis at all times during the machining of said next segment; means receptive of said instantaneous distance information from said interpolating means and said divergence for generating the proper instantaneous transverse dimension of the portion of said workpiece being cut; controllable means for driving the mandril of the lathe at a selected speed of rotation; and means for forming the ratio of the cutting rate to said instantaneous transverse dimension for generating an output proportional to said ratio to control the rotational speed at which said mandril drive means drives said mandril for effecting the optimum cutting rate as a function of the divergencne of the tool.