Abstract: In an annular member forming apparatus including: a forming roll rotatable in contact with an outer cylindrical surface of an annular workpiece; a mandrel relatively movable towards and away from the forming roll in contact with an inner cylindrical surface of the workpiece; and an outside diameter detecting device for detecting an outside diameter of the workpiece which is to be worked, the apparatus further includes a moving device for moving relatively the forming roll and the mandrel and for pressing the workpiece by the forming roll and the mandrel moved towards each other to subject the workpiece to rough rolling and to finish rolling. The moving device includes a retracting device for correcting an elastic deformation of the forming roll, the mandrel and the moving device occurring during the rough rolling, for a switching time from the rough rolling to the finish rolling by an output signal from the outside diameter detecting device.

Abstract: In an annular member forming apparatus including: a forming roll rotatable in contact with an outer cylindrical surface of an annular workpiece; a mandrel relatively movable towards and away from the forming roll in contact with an inner cylindrical surface of the workpiece; and an outside diameter detecting device for detecting an outside diameter of the workpiece which is to be worked, the apparatus further includes a moving device for moving relatively the forming roll and the mandrel and for pressing the workpiece by the forming roll and the mandrel moved towards each other to subject the workpiece to rough rolling and to finish rolling. The moving device includes a retracting device for correcting an elastic deformation of the forming roll, the mandrel and the moving is device occurring during the rough rolling, for a switching time from the rough rolling to the finish rolling by an output signal from the outside diameter detecting device.