Patent ID: 9084297
Filing Date: 2015-07-14
Classification: C21D,C22C,H05B,Y02P

Abstract:
1. A method of electric induction heat treatment of at least one circular surface of an annular workpiece, the method comprising the steps of: positioning side-by-side a first and a second inductor at an initial position adjacent to the at least one circular surface, the initial position located within an oscillatory arc zone of the at least one circular surface, the oscillatory arc zone having a first and a second arc boundary; supplying an oscillatory zone alternating current to the first and second inductors while circumferentially moving side-by-side the first and second inductors repeatedly between the first and second arc boundaries for a pre-heat period of time while adjacent to the at least one circular surface; supplying a steady state heat treatment power having a steady state power magnitude and frequency to the first and second inductors while separating the first and the second inductors in the oscillatory arc zone by moving the first inductor in a first circumferential direction adjacent to the at least one circular surface to a first inductor end steady state heat treatment position less than 180 degrees opposite the initial position at a steady state scan rate, and by moving the second inductor in a second circumferential direction adjacent to the at least one circular surface to a second inductor end steady state heat treatment position at the steady state scan rate, the second circumferential direction opposite to the first circumferential direction; directing a first quenchant spray from a first quench apparatus to impinge on a first inductor heated region of the at least one circular surface heated by the first inductor as the first inductor moves in the first circumferential direction to the first inductor end steady state heat treatment position after the first inductor separates from the second inductor by a spray interference distance, and directing a second quenchant spray from a second quench apparatus to impinge on a second inductor heated region of the at least one circular surface heated by the second inductor as the second inductor moves in the second circumferential direction to the second inductor end steady state heat treatment position after the second inductor separates from the first inductor by the spray interference distance; removing the steady state heat treatment power from the first inductor and terminating the first quenchant spray after the first inductor completes heat treatment at the first inductor end steady state heat treatment position; moving the second inductor in the second circumferential direction after the second inductor completes heat treatment at the second inductor end steady state heat treatment position to the end of an extended end scan region to heat treat the extended end scan region at an end of heat treatment scan rate faster than the steady state scan rate and at an end of heat treatment power magnitude and frequency; and directing the second quenchant spray to impinge on the extended end spray region by alternatively repositioning the second quench apparatus while the second inductor is at the end of the extended end scan region or moving the second quench apparatus through the extend end spray region.