National Forge Company

Paul Duliba

Ashok K Khare

A method for induction hardening through hardened chromium-molybdenum hot work die steel comprising the steps of induction heating to a uniform temperature above the upper critical temperature, cooling, and double tempering at temperatures below the lower critical temperature to produce a workpiece having a tough core and a hard wear resistant surface. An apparatus is provided for induction hardening long workpieces with minimum distortion by providing an inductor coil which always remains centered around the workpiece during induction coil traverse. Mandrel bars for tube piercing mills can be induction hardened using this process and apparatus.

Induction hardening of steel

A method of and apparatus for machining a pre-selected contour in a surface of a workpiece, such as an end face of the workpiece. The workpiece is rotated on a lathe about its longitudinal axis and a cutting tool, mounted on a movable cross slide of the lathe, is positioned parallel to the longitudinal axis of the workpiece for cutting a contour into the workpiece end face. A probe, also mounted on the cross slide, is positioned perpendicular to the longitudinal axis of a pattern for continual contact with the outer surface of the pattern, which is being rotated about its longitudinal axis. Upon rotation of the pattern and workpiece and movement of the cross slide, the probe moves towards and away from the longitudinal axis of the pattern in accordance with a change in the distance from the point of probe contact with the pattern outer surface to the longitudinal axis of the pattern. A command potentiometer detects the distance and direction of probe movement and an electrohydraulic servo system moves the cutting tool in response to direction from the potentiometer a proportional distance towards and away from the end face of the workpiece, whereby the cutting tool cuts a contour in the workpiece end face.

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Warren, PA, United States of America

Paul Duliba