公开(公告)号：US20210187591A1

公开(公告)日：2021-06-24

申请号：US16640131

申请日：2018-07-30

申请人： NIPPON STEEL CORPORATION

发明人： Junichi OKUBO ,  Kenji TAMURA ,  Kunihiro YOSHIDA ,  Sam Soo HWANG ,  Ryusuke NAKANO ,  Masao HORI ,  Yukihiro OTA

IPC分类号： B21K1/08 ,  B21J5/02

摘要： 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.