To provide a manufacturing method of a con'rod superior in symmetric property of cross-sectional shape of a column portion and having high buckling strength.
This method of manufacturing the con'rod includes a hot forging process, a trimming process and a cold coining process. In the trimming process, a trimming die 5 having a trimming hole 50 and a burr cutting blade 51 mounted around the hole, is used, the con'rod is inserted into the trimming hole 50 of the trimming die 5 so that burr 2 is brought into contact with the burr cutting blade 51, a restraint die 6 is brought into contact with at least the column portion 13 of the con'rod penetrated through and projecting from the trimming hole 50 for restricting ribs 131 at both sides of the column portion 13 so that they are prevented from being deformed in the opening direction, and the con'rod is pressed by a pressing die 4 to press the burr 2 to the burr cutting blade 51 to cut the burr 2 while keeping the restraining state of the column portion 13 by the restraint die 6.
MIZUNO HIROYUKI
HAYAKAWA HIROKATSU
KINO KINSEI
MORI MOTOHIDE
FUJITA TAKASHI
TAKADA HIROTADA
TARUI TOSHIZO
TOYOTA MOTOR CORP
NIPPON STEEL CORP
Tamiwa Iwakura
Takahashi Shoki
Next Patent: CON'ROD MANUFACTURING METHOD