Method for manufacturing ring-rolled product

A method for manufacturing a ring-rolled product, the method forming the ring-rolled product from a ring material by using a rolling device, the rolling device including a mandrel roll, a main roll, a guide roll, and at least one induction heating element, the mandrel roll and the main roll being rotatable, the mandrel roll and the main roll being configured so as to respectively contact inner and outer circumferential surfaces of the ring material in a state in which the ring material is rotated in a circumferential direction thereof, the mandrel roll and the main roll being configured so as to press the ring material in a radial direction thereof, the at least one induction heating element being configured so as to induction-heat the ring material, wherein

• the guide roll is rotatably disposed on an outer circumferential side of the ring material within a region immediately before inner and outer circumferential rolling, which is sandwiched by a reference line segment and a boundary line segment in the circumferential direction of the ring material, the reference line segment connecting a rotation axis of the ring material and a rotation axis of the main roll in the radial direction of the ring material, the boundary line segment being disposed so as to be rotated around the rotation axis of the ring material from the reference line segment toward a direction opposite of a rotation direction of the ring material, by an angle of 90 degrees or less, and the guide roll is configured so as to be contactable to the ring material,
• the at least one induction heating element includes an outer circumferential side induction heating element which is disposed on an outer circumferential side of the ring material so as to induction-heat an outer circumferential side region of the ring material, and which is configured to be movable,
• the method comprises a step of carrying out ring rolling having an operation of rolling the ring material by using the rolling device, in this step, a diameter of the ring material being enlarged in the ring rolling, and the ring material being induction-heated by the at least one induction heating element in the ring rolling, wherein
• the outer circumferential side induction heating element moves such that when seen from an axial direction of the ring material, before an intermediate stage of the ring rolling, in the circumferential direction of the ring material, a length of a heating element disposition space which is located on an outer circumferential side of the ring material within the region immediately before inner and outer circumferential rolling and is located between the guide roll and the boundary line segment within this region, is half a length of the outer circumferential side induction heating element or less, and a center of the outer circumferential side induction heating element in a direction which corresponds to a circumferential direction of the outer circumferential side region of the ring material, is located outside the region immediately before inner and outer circumferential rolling, and after the intermediate stage in the ring rolling, a diameter of the ring material is enlarged so that in the circumferential direction of the ring material, the length of the heating element disposition space in the region immediately before inner and outer circumferential rolling is larger than half the length of the outer circumferential side induction heating element, and the center of the outer circumferential side induction heating element is disposed within the region immediately before inner and outer circumferential rolling in the circumferential direction of the ring material, and the outer circumferential side induction heating element induction-heats the ring material.