Abstract: A method for producing a ring core having a plurality of separate core plates with lobes defined on an inner circumferential surface thereof, the separate core plates being arranged and stacked in a ring-shaped pattern. The method includes the steps of supporting the separate core plates with either one of an inner guide member being disposed radially inwardly of the separate core plates stacked in the ring-shaped pattern and an outer guide member disposed radially outwardly of the separate core plates, and applying a pressure from the other of the inner guide member and the outer guide member, wherein the inner guide member has recesses corresponding to the lobes for positioning and supporting the lobes, and stacking the separate core plates in the ring-shaped pattern to form the ring core, while rotating the separate core plates in unison through a predetermined angle with the inner and outer guide members.

Abstract: In the device for producing a ring core, a drop-through blanking die (46) constituting a rotor core production line (30) is used to mold a ring core by laminating a plurality of split core plates (12, 16) while arranging them in a ring shape. The drop-through blanking die (46) consists of a rotary mechanism (55) for rotating the split core plates (12, 16) thus laminated through a predetermined angle, an inner guide member (62) being arranged on the inner circumferential side of the split core plates (12, 16) laminated in a ring shape, and an outer guide member (58) being arranged on the outer circumferential side of the split core plates (12, 16). While the split core plates (12, 16) are supported by any one of the inner guide member (62) and the outer guide member (58), a pressure is imparted to the split core plates (12, 16) by the other.