Abstract: A method and apparatus for inductively heating valve seats wherein an inductor is driven to a predetermined magnetic coupling with the valve seat under the control a range detecting transceiver unit.

Abstract: A method and apparatus for heating a conical valve seat surface of a valve seat ring insert which has been previously press fitted or molded into an engine component such as an engine head. The method and apparatus includes mounting an inductor for reciprocal movement axially toward and away from the valve seat of the engine head and biasing the inductor toward the valve seat, encircling the inductor with an axially biased electrically conducting hollow ring-shaped magnetic flux shield through which a coolant is circulated, and moving the inductor and conducting ring shield toward the valve seat of the engine head to locate the inductor in a preselected position providing the necessary magnetic coupling gap between the inductor and valve seat surface of the valve seat insert while the conducting ring shield is maintained in heat transfer surface contact with and stray flux shielding relation to the portion of the engine head immediately around the valve seat surface of the insert.

Abstract: An apparatus for heating an elongated workpiece having an elongated axis and moving along a heating path in a selected linear direction, the path having opposite sides defining a workpiece passage therebetween. This apparatus comprises a plurality of high permeability flux directing elements, each of the elements having a generally flat surface spaced from and generally parallel to the heating path, means for mounting the elements along at least one side of the path at selected, mutually spaced locations, separate coil means encircling each of said elements and alternating current power means for causing separate, spaced magnetic flux fields extending from said surfaces and into said passage in a direction generally perpendicular to said path.

Abstract: A desirable relative positional relationship between an inductor and a workpiece to be heated is detected by an electrical circuit which is closed upon relative movement of the inductor and workpiece to the desired relative position. The detecting circuit includes a contact positioned relative to the inductor and engagable with the workpiece upon relative movement of the inductor and workpiece in one direction. Upon such engagement a circuit is completed to stop relative movement in the one direction.