Abstract: In a method for manufacturing a motor core, when a crimping part for crimping and fastening electromagnetic steel plates is formed, the crimping part includes a crimping straight part, crimping tapered parts disposed on both sides of the crimping straight part, and crimping shoulder parts, the crimping shoulder parts being stepped parts formed between a planar part of other areas of the crimping part and end parts of the crimping tapered parts. When a plate thickness of the planar part is represented by T; a height of the crimping shoulder parts is represented by A; and a height of the crimping straight part is represented by B, below-shown Expressions 1 to 3 are satisfied. B - A ? T ( Expression ? 1 ) 0.9 T ? B ? 1.2 T ( Expression ? 2 ) 0 < A ? 0.

Abstract: A technique disclosed herein relates to a method for producing a plate piece including a partial outline and a remaining outline continuous from the partial outline. The method disclosed herein may comprise removing an outer region external to the partial outline from a plate workpiece by a first punch (first punching process); and punching out an inner region internal to the remaining outline by a second punch from the plate workpiece in which the outer region has been removed while applying a block to a side surface of the plate workpiece along the partial outline (second punching process). In the second punching process, by applying the block to the side surface of the already-formed partial outline, deformation of the partial outline can be suppressed when the inner region internal to the remaining outline is punched out by the second punch.