Abstract: A method of hardening a work piece having (i) an outer surface, (ii) an inner surface which defines a passageway extending through the work piece, and (iii) an end. The method includes the steps of (A) advancing the work piece through a first induction coil such that a first hardened area is formed on the work piece, (B) advancing a second induction coil into the passageway of the work piece such that a second hardened area is formed on the work piece, and (C) positioning a third induction coil adjacent to the end of the work piece such that a third hardened area is formed on the work piece. The positioning the third induction coil step is performed after (i) the advancing the work piece through the first induction coil step and (ii) the advancing a second induction coil into the passageway step.

Abstract: Conventional methods for heat treating cylindrical components such as track bushings involve multiple steps. For example, many such methods consist of carburizing, cooling, induction-hardening, quenching, and tempering. The conventional methods have proved to be costly because different heat treating apparatus are required. This causes duplicate handling and wasted manufacturing time. The present invention provides a method and apparatus 30 for heat treating a bushing 10 simultaneously from an outer peripheral surface and the pair of inner circumferential surfaces.

Abstract: Conventional methods for heat treating cylindrical components such as track bushings involve multiple steps. For example, many such methods consist of carburizing, cooling, induction-hardening, quenching, and tempering. The conventional methods have proved to be costly because different heat treating apparatus are required. This causes duplicate handling and wasted manufacturing time. The present invention provides an apparatus 30 for heat treating a bushing 10 simultaneously from an outer peripheral surface 12 and the pair of inner circumferential surfaces 20.