Abstract: A preform for a connecting rod of an engine is manufactured with a good productivity. The preform has a large-end mass portion which corresponds to a large-end portion of the connecting rod, a small-end mass portion which corresponds to a small-end portion thereof, and a shaft portion which corresponds to a rod portion thereof. There is manufactured a preform blank which has a shaft-shaped portion which is formed by extrusion. This shaft-shaped portion is made up of the shaft portion and an extended portion which extends axially forward from the shaft portion. The small-end mass portion is formed by squeezing the extended portion in the axial direction in a plurality of times starting with a portion near the shaft portion.

Abstract: A connecting rod is formed by cold forging in a single pressing cycle at a good accuracy without separately preparing a large-end cap, to thereby reduce the manufacturing cost. A double-action type of forging apparatus is made up of an upper die, a lower die, and a large-end portion punch and a small-end portion punch, both being movably provided in each of the dies. The upper die is closed to the lower die while forging a preform, to thereby roughly form a connecting rod. Then, the large-end portion punch and the small-end portion punch are protruded into a forming space between both the upper and lower dies to forge the parts to be pierced, thereby filling underfilled parts with material. Then, the large-end portion punch and the small-end portion punch on the side of the upper die are pushed out of the forming space to reach the lower die. The underfills left in the parts to be pierced are blanked or punched away to form a large-end hole and a small-end hole.