Apparatus for machining surface of revolution having discontinuities

Claim 1

Apparatus for generating a surface of revolution having discontinuities on a workpiece by means of a ceramic tool, comprising: a. a base, b. a tool support mounted on the base and rotating the tool about the axis of the surface of revolution, c. a workpiece support slidably mounted on the base for feeding movement in the direction of the surface of revolution, and d. first control means regulating the rate of rotation of the tool and the speed of the feeding movement of the workpiece support so that the resultant speed of the tool through the workpiece is slow at a position adjacent a discontinuity and relatively rapid at a position remote from a discontinuity, the first control means being comprised of a variable speed motor driving a rotatable spindle on which the tool is mounted, of a hydraulic cylinder connected between the base and the tool support for moving the workpiece support, of a servo valve connected by hydraulic lines to the cylinder for regulating the cylinder, of a screw for adjusting the valve, of a motor connected to the screw for rotating the screw, and a second control means between the tool and the motor to maintain the lead of the helical path followed by the tool on the workpiece to remain constant irrespective of changes in rate of rotation of the spindle, the second control means comprising means provided on the workpiece support and the base corresponding to the location of disconuities in the workpiece surface relative to the tool and means to signal the first control means that the tool is arriving at the discontinuity.