Multi-frequency heat treatment of a workpiece by induction heating

• Main Authors: DON L. LOVELESS, VALERY I. RUDNEV
• Format: Patent
• Language: English
• Published: 03.03.2011
• Subjects: CHEMISTRY; ELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS

An apparatus and process are provided for multi-frequency induction heat treatment of workpieces including gears. High frequency power is applied to an induction coil that surrounds the workpiece so that a high frequency magnetic field couples with the workpiece to inductively heat the workpiece. A C-core inductor is coupled to a coil that has low frequency power applied to it. The workpiece is inserted in a gap in the C-core inductor magnetic circuit so that it experiences low frequency Joule effect heating when the low frequency current is applied to the coil coupled with the C-core inductor. Alternatively the workpiece may be inserted around the C-core inductor when the workpiece has an opening.