公开(公告)号：US20200086378A1

公开(公告)日：2020-03-19

申请号：US16470002

申请日：2017-10-17

Applicant: NIPPON STEEL CORPORATION

Inventor： Kenji TAMURA ,  Junichi OKUBO ,  Kenji IMANISHI ,  Kunihiro YABUNO ,  Sam Soo HWANG ,  Sho TAKAMOTO ,  Tadanao ISHII ,  Koichiro ISHIHARA

IPC: B21K1/08 ,  F16C3/08

Abstract: A production method includes a forging step, a flash-trimming step, and a pressing step. In the forging step, a finish-forged product with flash is formed by an upper forging, die and a lower forging die. In the forging step, an excess portion is formed on at least one crankarm which is connected to a first or third pin, in a portion near the first or third pin, on an outer periphery of a lateral part near the upper forging die, such that the excess portion protrudes from the outer periphery. In the pressing step, the excess portion is pressed by an upper die such that the excess portion bulges toward a journal. This method allows production of a forged crankshaft with a reduced weight and a sufficient rigidity in a simple facility.