A piston manufacturing device includes a first forming device (42) configured to form an annular groove (61) in a piston (11), and a second forming device (52) configured to press an edge (15) of an opening (14) of the piston (11) toward other end side in an axial direction of the piston (11) and to form a thick section (65) extruded from an inner circumferential surface (12b) arranged between the edge (15) and the groove (61) toward an axial center side of the piston (11), wherein a recessed section (53) is formed at a portion of the second forming device (52) that is arranged to abut the edge (15) so that an inner circumferential side of the edge (15) is plastically deformed toward the other end side in an axial direction of the piston (11).

A method and apparatus for simultaneously producing a first piston part and a second piston part via a forging device may include an upper die, at least one intermediate die, and a lower die. A first billet may be placed between the upper die and the intermediate die, and a second billet may be placed between the intermediate die and the lower die. The upper die and the lower die may be configured to be moved toward each other, whereby the first piston part is forged from the first billet and the second piston part is forged at the same time from the second billet. The upper die and the lower die may then be configured to be moved apart, and the piston parts may be removed.

A method and apparatus for simultaneously producing a first piston part and a second piston part via a forging device may include an upper die, at least one intermediate die, and a lower die. A first billet may be placed between the upper die and the intermediate die, and a second billet may be placed between the intermediate die and the lower die. The upper die and the lower die may be configured to be moved toward each other, whereby the first piston part is forged from the first billet and the second piston part is forged at the same time from the second billet. The upper die and the lower die may then be configured to be moved apart, and the piston parts may be removed.