Patent ID: 8904634

Claim:
A forging method for producing a piston skirt of a piston having a piston axis, comprising: pressing a first for against a swage; forging two skirt walls at least slightly conically away from the piston axis via the first forging die; forging two box walls that connect the two skirt walls, wherein each box wall has a hub inside that is substantially parallel to the piston axis and a hub outside extending from a free end of the box wall at least slightly away from the piston axis via the first forging die; pressing a second forging die against a swage; moulding the box walls via the second forging die, wherein the hub outside of each box wall runs at least one of substantially parallel to the piston axis and slightly inwardly from the free end to the hub inside; and drawing, simultaneously with moulding the box walls, the skirt walls into a position that is approximately parallel to the piston axis; wherein the piston skirt is located between one of the forging dies and the swage throughout the method.