Method of inductively heating and quench hardening camshafts

A method of inductively heating and quench hardening an elongated camshaft having a central axis, an elongated body portion, at least three axially spaced bearings on said body portion and having bearing surfaces generally concentric with said axis and axially spaced cams on said body portion and having cam surfaces encircling said axis, said method comprising the steps of:

• a. providing a generally cylindrical multi-turn inductor having an elongated workpiece receiving opening extending in a given direction;
• b. rotatably mounting said camshaft in said workpiece receiving passage with said central axis extending in said given direction;
• c. rotating said workpiece about said given axis;
• d. energizing said inductor with a high frequency alternating current while said workpiece is rotating;
• e. continuing said energizing and rotating steps until said surfaces are inductively heated to a temperature above a quench hardening temperature and a part of said body portion is below a quench hardening temperature;
• f. then removing said workpiece from said workpiece receiving opening;
• g. before said surfaces cool below the quench hardening temperature, clamping said workpiece on at least three of said bearing surfaces for rotation about a quench axis corresponding to said workpiece central axis;
• h. restraining said at least three clamped bearing surfaces from transverse movement;
• i. before said surfaces cool below the quench hardening temperature, quenching said clamped and restrained workpiece with a quenching liquid until said surfaces are quenched to a temperature before the hardening temperature;
• and,
• j. rotating said clamped and restrained workpiece about said quench axis during said quenching step.