Abstract: A method and apparatus for circumferentially machining an out-of-round workpiece in which the workpiece is rotated about its longitudinal axis at an irregular angular speed.

Abstract: Apparatus for positioning a workpiece, such as a piston ring, which has an out-of-round inner circumferential face with a radially inwardly directed portion that deviates from the out-of-round contour. The apparatus includes first and second spaced cylindrical rollers each having a diameter which is substantially less than the diameter of the workpiece. Means are provided for rotating the rollers in the same direction about their respective longitudinal axes. Braking means, which is interposed between the rollers and may be in the form of a brake shoe, has a frontal face positioned with respect to the peripheral surfaces of the rollers so that the frontal face contacts only the portion of the inner circumferential face of the workpiece which deviates from the out-of-round contour.

Abstract: An apparatus for the non-circular peripheral machining of an out-of-round workpiece includes a lathe spindle for rotating the workpiece; a radially displaceable tool holder for carrying a tool to engage a peripheral face of the workpiece; a first and a second setting motor for displacing the tool holder in a radial direction during rotation of the lathe spindle; a first connecting device coupling the output of the first setting motor with the second setting motor and the tool holder for displacing, with incremental steps, the second setting motor and the tool holder as a unit in the radial direction; and a second connecting device coupling the output of the second setting motor with the tool holder for displacing, with incremental steps--that are of different magnitude from those of the first setting motor--the tool holder in the radial direction relative to the first connecting device and the first setting motor.