Patent ID: 8635982

Claim:
Method for the production of a piston ( 10 , 110 , 210 ) for an internal combustion engine, composed of a first piston component ( 11 , 111 , 211 ) and a second piston component ( 12 , 112 , 212 ), comprising the following method steps: (a) making available a blank ( 211 ′) of the first piston component ( 11 , 111 , 211 ) composed of a heat-treatable steel or a precipitation-hardenable steel, having at least one joining surface ( 29 , 31 ), and positioning the at least one joining surface ( 29 , 31 ) of the blank ( 211 ′) of the first piston component in such a manner that the at least one joining surface ( 29 , 31 ) lies within a partial region or partial structure of the piston to be produced, which is supposed to be hardened, (b) making available a blank ( 212 ′) of the second piston component ( 12 , 112 , 212 ) composed of a heat-treatable steel or a precipitation-hardenable steel, having at least one joining surface ( 32 , 33 ), and positioning the at least one joining surface ( 32 , 33 ) of the blank in such a manner that the at least one joining surface ( 32 , 33 ) of the blank of the second piston component lies within a partial region or partial structure of the piston to be produced, which is supposed to be hardened, (c) tempering or precipitation-hardening the blanks ( 211 ′, 212 ′), (d) connecting the blank ( 211 ′) of the first piston component ( 11 , 111 , 211 ) with the blank ( 212 ′) of the second piston component ( 12 , 112 , 212 ) by way of their joining surfaces ( 29 , 31 , 32 , 33 ), by means of friction welding, to produce a piston blank ( 210 ′), with the formation of at least one friction-welding seam ( 25 , 26 , 125 , 226 ) as well as a heat influence zone ( 30 , 30 ′) in the region of the at least one friction-welding seam ( 25 , 26 , 125 , 226 ), such that the at least one friction-welding seam ( 25 , 26 , 125 , 126 ) is positioned so that a partial region or partial structure of the piston which is supposed to be hardened, lies in the heat influence zone ( 30 , 30 ′), wherein at least one blank ( 211 ′, 212 ′) is provided with at least one ring groove ( 34 , 36 , 37 ) and at least one pair of corresponding joining surfaces ( 29 , 32 ) of the blanks ( 211 , 212 ) are positioned in such a manner that after step (d), the distance of a lower groove flank ( 34 ′) of a ring groove ( 34 ) from the center of the outer friction-welding seam ( 25 , 125 ) is less than the axial height of the heat influence zone ( 30 ) of this friction-welding seam ( 25 , 125 ), (e) annealing or low-stress annealing of the piston blank ( 210 ′) after the step of welding, thereby preserving the heat influence zone(s) ( 30 , 30 ′), (f) re-machining and/or finishing the piston blank ( 210 ′) to produce a piston ( 10 , 110 , 210 ).