Half die forging method and half die forging device of crank throw for large ship

The invention discloses a half die forging method and a half die forging device of a crank throw for a large ship. The half die forging method includes the flowing steps: removing the head portion and the tail portion of a steel ingot, forging and pressing the steel ingot to a flat billet with a boss in the middle of the flat billet, conducting lateral press at the same time to the boss of a pre-formed blank by using two symmetrical side press clamp round models, clamping a round part of a pin part, embedding and pressing the blank after the blank is laterally pressed by using a bend forging upper die and a crank throw pin part forming die, bending forging, and conducting secondary bending forging and repair by using an upper flat anvil and a lower flat anvil. The side press clamp round models is are used for replacing an existing V-shaped die, and the crank throw pin part forming die is added, the shape of a crank throw pin part after half die forging is close to a circle, slopes of two sides are formed at t