Method for producing a piston for an internal combustion engine

Method for production of a piston (10, 110) for an internal combustion engine, having a basic piston body (11, 111) and a piston ring element (12, 112), wherein the basic piston body (11, 111) has at least a piston skirt (15, 115) and at least a bottom region (27, 127) of a combustion bowl (21, 121), wherein the piston ring element (12, 112) has a piston crown (19, 119), at least one wall region (28, 128) of the combustion bowl (21, 121), a circumferential top land (22, 122), and at least one part of a circumferential ring belt (23, 123) provided with ring grooves, and wherein the basic piston body (11, 111) and the piston ring element (12, 112) form a circumferential closed cooling channel (24, 124), comprising the following method steps:

• (a) providing a first blank (11′, 111′, 211′) of the basic piston body (11, 111), in which an outer circumferential joining surface (29, 129, 229) and an inner circumferential joining surface (31, 131, 231), widened in the direction of the bottom region (27, 127) of the combustion bowl (24, 124), as well as a lower cooling channel part (24a, 124a, 224a) that runs circumferentially between the two joining surfaces (29, 31;
• 129, 131;
• 229, 231) are pre-machined;
• (b) providing a second blank (12′, 112′, 212′) of the piston ring element (12, 112), in which an outer ring-shaped joining surface (32, 132, 232) and an inner ring-shaped joining surface (33, 133, 233) as well as an upper cooling channel part (24b, 124b, 224b) that runs circumferentially between the two joining surfaces (32, 33;
• 132, 133;
• 232, 233) are pre-machined;
• (c) joining the first blank (11′, 111′, 211′) with the second blank (12′, 112′, 212′) by way of their joining surfaces (29, 129, 229;
• 31, 131, 231;
• 32, 132, 232;
• 33, 133, 233), to produce a piston blank (10′, 110′), in such a manner that a partial region (34, 134, 234) of the widened joining surface (31, 131, 231) of the first blank (11′, 111′, 211) remains standing free and uncovered by the second blank, at least in the bottom region (27, 127) of the combustion bowl (24, 124);
• (d) post-machining and/or finishing the piston blank (10′, 110′) to produce a piston (10, 110), including removal of the partial region (34, 134, 234) of the widened joining surface (31, 131, 231).