Method for producing forged crankshaft

• Main Authors: Hwang, Samsoo, Okubo, Junichi, Tamura, Kenji, Yoshida, Kunihiro, Hori, Masao, Nakano, Ryusuke
• Format: Patent
• Language: English
• Published: 29.10.2019
• Subjects: BEARINGS; BLASTING; ELEMENTS OR CRANKSHAFT MECHANISMS; ENGINEERING ELEMENTS AND UNITS; FLEXIBLE SHAFTS; FORGE FURNACES; FORGING; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; HAMMERING; HEATING; LIGHTING; MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES,RIVETS, BOLTS OR WHEELS; MECHANICAL ENGINEERING; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; PERFORMING OPERATIONS; PRESSING METAL; PUNCHING METAL; RIVETING; ROTARY BODIES OTHER THAN GEARING ELEMENTS; SHAFTS; THERMAL INSULATION IN GENERAL; TRANSPORTING; WEAPONS

A forged crankshaft production method includes a first preforming step, a second preforming step, and a final preforming step. The first pair of dies includes web processing parts to come into contact with portions to be formed into arms and portions to be formed into weights integrated with the arms. Each of the web processing parts includes an arm processing part and a weight processing part. The arm processing part and the weight processing part form a recessed portion, and the width of the open side of the weight processing part becomes greater with increasing distance from the bottom of the recessed portion. Accordingly, in the blank, volume can be distributed between a portion to be formed into an arm and a portion to be formed into a weight integrated with the arm, and the material yield rate can be improved.