METHOD FOR PRODUCING FORGED CRANKSHAFT

• Main Authors: HORI, Masao, OKUBO, Junichi, TAMURA, Kenji, NAKANO, Ryusuke, YOSHIDA, Kunihiro, HWANG, Samsoo
• Format: Patent
• Language: English; French; German
• Published: 16.10.2019
• Subjects: MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES,RIVETS, BOLTS OR WHEELS; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; PERFORMING OPERATIONS; PUNCHING METAL; TRANSPORTING

A forged crankshaft production method includes a first preforming step, a second preforming step, and a final preforming step. In the first preforming step, a workpiece is pressed by a first pair of dies. Thereby, sectional areas of portions to be formed into pins and sectional areas of portions to be formed into journals are decreased, whereby flat portions (23a) are formed, and the portion to be formed into the pin (PA2) located at a second position (L2) is decentered. In the second preforming step, an initial blank (23) obtained by the first preforming step is pressed by a second pair of dies. Thereby, a portion to be formed into the pin (PA1) located at a first position (L1) is decentered, and a portion to be formed into the pin (PA3) located at a third position (L3) is decentered to a side opposite to the portion to be formed into the pin (PA1) located at the first position. In a blank obtained thereby, portions to be formed into pins have been pressed and decentered, and the material yield rate can be improved.