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Abstract

Provided is a production method, including a first preforming process for obtaining a first preform from a billet, a second preforming process for obtaining a final preform from the first preform, and a finish forging process for forming the final preform into a finishing dimension of a forged crankshaft. In the first preforming process, a plurality of flat parts are formed by pressing pin-corresponding parts and journal-corresponding parts in a direction perpendicular to an axial direction of the billet. The second preforming process includes: a process of pressing regions to be a plurality of journals with a width direction of the flat part as a pressing direction by using a pair of first dies; and a process of, after starting pressing by the first dies, decentering regions to be a plurality of pins with the width direction of the flat part as a decentering direction by using second dies.

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First Claim