Flux guide induction heating device and method of inductively heating elongated and nonuniform workpieces

A method of induction heating an elongated and electrically conductive workpiece, comprising:

• using two flux guides, each flux guide having a closed geometric configuration except at a gap which extends transversely across each flux guide,
• separating the two flux guides laterally with respect to one another at the gaps in each of the flux guides;
• using space between the two laterally separated flux guides as openings;
• conducting alternating magnetic flux in the flux guides;
• allowing the magnetic flux to flow from the flux guides through the gaps;
• extending the elongated workpiece within the openings on opposite sides of the gaps with a selected portion of the elongated workpiece extending in a direction aligned with the direction of flux flow across the gaps;
• allowing magnetic flux from the flux guides to flow from the openings into the elongated workpiece and through the selected portion of the workpiece at the gaps;
• establishing a difference in an amount of magnetic flux flowing through the selected portion of the workpiece at the gaps compared to an amount of magnetic flux flowing exterior of the selected portion of the workpiece at the gaps which is sufficient to induce eddy currents to flow circumferentially around the selected portion of the workpiece at the gaps to heat the selected portion;
• and
• maintaining the selected portion of the workpiece at the gaps for a predetermined amount of time sufficient for the circumferential eddy currents to heat the selected portion of the workpiece at the gaps.