METHOD AND APPARATUS FOR INDUCTIVELY HEATING VALVE SEAT INSERTS FOR HARDENING THE SEAT SURFACES

摘要

A method and apparatus for heating a conical valve seat surface (24) of a valve seat ring insert (16) which has been previously press fitted or molded into an engine component such as an engine head (12). The method and apparatus includes mounting an inductor (28) for reciprocal movement axially toward and away from the valve weat 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 (50) through which a coolant is circulated, and moving the inductor and conducting ring shield toward the valve seat of the engine head while the conducting ring shield (50) is maintained in heat transfer surfase contact with and stray flux shielding relation to whe portion of the engine head (12) immediately around the valve seat surface of the insert.