Sequential crankshaft forging process - uses ring of square cross-section hammer forged to produce good grain flow

摘要

A crankshaft is forged from a circular blank in the following sequence of operations. A hole is first punched in the blank to form a ring. The ring is then hammer forged to achieve a square cross-section equal to the cross-sectional area of the crankpin of the finished crankshaft. The ring is then deformed to an oval shape and then to a rectangular block with a rectangular slot. The wall at one end of the slot is removed whilst the opposite wall is forged to a circular section to form the crankpin. Finally transverse holes are formed to receive the main bearing shafts. This system produces a good grain flow in the metal.