Patent ID: 7918022

Claim:
A method of producing a cooling channel piston for an internal combustion engine which has a cooling channel in a piston crown comprising the steps of: providing a piston lower section with piston bosses, piston pin bores and piston skirts attached to the piston crown; producing first a piston blank with a circumferential collar projecting radially outward in an area of the piston crown at an angle of about 90° relative to an axis of piston stroke; forming a seating area from the piston blank for the collar in a transition zone between the piston crown and the piston lower section; and then forming over the collar by bending an outer radially circumferential part of the collar at an angle of about 90° relative to an inner radially circumferential portion of the collar in such manner until an outer radially circumferential edge of the collar comes at least one of very close to and butts completely against the seating area to form a closed cooling channel.