Abstract: An apparatus in the form of a die assembly for building a laminated core comprising a plurality of core sheets laminated one above another. Each of the core sheets has a plurality of caulking projections formed therein in the equally spaced relation which serve to achieve caulking between the adjacent core sheets. Prior to punching operation the blanking die is turned by a predetermined angle which is determined by a combination of gear ratio of the gearing mechanism and that of the indexing mechanism. A sprocket on the blanking die is operatively connected to a sprocket on the output shaft of the gearing mechanism and a sprocket on the input shaft of the gearing mechanism is operatively connected to a sprocket on the output shaft of the indexing mechanism.

Abstract: In a metallic mold apparatus, a rotational power for a skewing operation and a rotational power for an indexing operation are applied through a differential gear device to a rotatably supported die. More specifically, the skew power from such an electric motor as a servomotor operative in synchronism with a press operation and the indexing power from an index means operatively coupled to a press are applied to the differential gear device.

Abstract: A method and apparatus for producing laminated iron cores wherein a new skew angle .DELTA..theta. is calculated when the total thickness of core sheets in a laminated iron core currently being produced reaches a predetermined value L.sub.o, or during a time period after the number of such laminated core sheets reaches a predetermined value n.sub.A before the total thickness reaches the predetermined value L.sub.o, so that a skewing operation for laminated iron core to be next made is carried out on the basis of the new skew angle .DELTA..theta..