US 8,635,982 B2Granted

Piston for an internal combustion engine and method for its production

AssigneeMahle International GmbH

InventorsRainer Scharp, Klaus Keller

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Abstract

A method for producing a piston for an internal combustion engine, composed of first and second piston components, has the following steps: (a) providing a blank of the first piston component composed of a tempered or precipitation-hardened steel, having at least one joining surface, (b) providing a blank of the second piston component composed of a tempered or precipitation-hardened steel, having at least one joining surface, (c) tempering or precipitation-hardening the blanks, (d) friction-welding the joining surfaces of the blanks to produce a piston blank, with the formation of at least one friction-welding seam and a heat influence zone in the region of the at least one friction-welding seam, (e) annealing or low-stress annealing of the piston blank, thereby obtaining the heat influence zone(s), (f) re-machining and/or finishing the piston blank to produce a piston. A piston so produced is also provided.

Claims16

Dependent claims

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).

4 more elements

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), whereby the piston (10, 110, 210) has a piston crown (19), a circumferential top land (21), and a circumferential ring belt (22) provided with ring grooves (34, 36, 37), as well as a piston skirt (15), wherein the first piston component (11, 111, 211) and the second piston component (12, 112, 212) consist of a tempered steel or a precipitation-hardened steel, and are connected with one another by means of friction welding, wherein the at least one friction-welding seam (25, 26, 125, 226) is surrounded by a heat influence zone (30, 30′), and wherein the at least one friction-welding seam (25, 26, 125, 126) is positioned in such a manner that the distance of a lower groove flank (34′) of a ring groove (34) from the center of the friction welding seam (25,125) is less than the axial height of the heat influence zone (30) of this friction welding seam (25, 125).

(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 (11, 111, 211) in such a manner that the at least one joining surface (29, 31) lies within a partial region or a 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 (212′) of the second piston component (12, 112, 212) in such a manner that the at least one joining surface (32, 330) lies within a partial region or a 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, 226) 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′),
(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);
wherein the piston blank (210′) is provided with at least one ring groove (34, 36, 37), in such a manner that 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).

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/066,550Filed 18 Apr 2011
Priority: DE 10 2010 033 88110 Aug 2010
Published: US 2012/0037111 A116 Feb 2012
Granted: 28 Jan 2014
Term ends: Not estimatedThe source records don’t support an estimate.

Classification14 codes

C21D 9/0068
Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor: for particular articles not…
B23K 20/129
The heat being generated by friction; Friction welding: specially adapted for particular articles or work
C21D 9/50
Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor: for welded joints
F02F 3/003
Multi-part pistons: the parts being connected by casting, brazing, welding or clamping