Patent ID: 8631573

Claim:
A method for the production of a piston for an internal combustion engine, having a piston base body and a piston ring element, the piston base body having at least a piston skirt and the piston ring element having at least a piston crown, a circumferential top land, and a circumferential ring belt provided with ring grooves, wherein the piston base body and the piston ring element form a circumferential, closed cooling channel, the method comprising the following steps: (a) providing a blank of a piston base body, in which an outer joining surface and an inner joining surface as well as a circumferential lower cooling channel part that runs between the two joining surfaces are pre-machined, (b) providing a blank of a piston ring element, in which an outer joining surface and an inner joining surface as well as a circumferential upper cooling channel part that runs between the two joining surfaces are pre-machined, (c) forming a circumferential widened region on the inner and outer joining surface of at least one of the blank of the piston base body and the blank of the piston ring element, the widened regions extending toward the related cooling channel part, (d) connecting the blank of the piston base body with the blank of the piston ring element by way of their joining surfaces by means of friction welding, to produce a piston blank, wherein the blank of the piston base body or the blank of the piston ring element is put into rotation, the blank of the piston base body and the blank of the piston ring element are pressed together, at an initial contact pressure with reference to the joining surface, the rotation is stopped, while maintaining the initial contact pressure, and after the rotation has come to a stop, the contact pressure is immediately increased to a multiple of the initial contact pressure, to metallurgically connect the blank of the piston base body and the blank of the piston ring element, and (e) machining the piston blank further or finish-machining the piston blank to produce a piston.