Patent ID: 8178038

Claim:
An induction coil apparatus for hardening undercut fillets of a workpiece, the apparatus comprising: a coil assembly comprising: an active turn coupleable to an electric power source to form a first conductive circuit, the active turn having at least one active coupling section and at least one crossover section, the at least one crossover section operative when the coil assembly is located proximate a workpiece to heat at least a portion of a journal area in a recess of the workpiece, and a passive turn electrically isolated from the active turn and forming a second conductive circuit, the passive turn having at least one passive coupling section and at least one passive heating section, the passive turn translatable relative to the active turn between a first position in which the passive heating section clears a recess sidewall as the coil assembly is translated radially toward a recess in the workpiece and a second position in which the passive coupling section is proximate to and electromagnetically coupled with the active coupling section of the active turn and in which the passive heating section is located proximate to an undercut fillet area of the workpiece recess.