Patent ID: 8974613
Filing Date: 2015-03-10
Classification: B21B,C21D,F16C,Y02P

Abstract:
1. A method of quenching a ring shaped article, which comprises: heating the ring shaped article to a quenching temperature, the heating comprising heating by induction heating the ring shaped article to a predetermined preheating temperature near to the quenching temperature, stopping the heating by induction heating and transferring the ring shaped article to a continuous heating furnace, and heating by soaking the ring shaped article, which has been previously heated to the preheating temperature, to the quenching temperature within the continuous heating furnace; primarily cooling the ring shaped article, which has been heated to the quenching temperature, down to a deformation correction initiating temperature, which is higher than a martensitic transformation point; and secondarily cooling the ring shaped article, which has been cooled down to the deformation correction initiating temperature, down to a temperature lower than the martensitic transformation point by, while a pair of receiving rolls are held in contact with an outer peripheral surface of such ring shaped article for rolling motion about an axis of rotation, which is parallel to a center of the ring shaped article, pressing a press roll, rotatable about an axis of rotation parallel to the center of the ring shaped article, against the outer peripheral surface of the ring shaped article from one side of the ring shaped article opposite to a point intermediate between the receiving rolls, wherein the heating by induction heating includes providing a rotary table and a heating coil, placing the ring shaped article on the rotary table, arranging the heating coil such that a position of the heating coil is adjustable in a direction radially of the rotary table so as to straddle between inner and outer peripheral surfaces of the ring shaped article, and turning the ring shaped article, placed on the rotary table, about the center of the ring shaped article, and the heating coil is of a downwardly oriented U-shaped configuration or has a structure in which two U-shaped conductors are so arranged as to permit their leg conductors to extend parallel to each other, one of the leg conductors having their free ends connected with each other through a connecting conductor.