Piston for an internal combustion engine and method for its production

• US 20120037111A1
• Filed: 04/18/2011
• Published: 02/16/2012
• Est. Priority Date: 08/10/2010
• Status: Active Grant

• Current Assignee: Mahle International GmbH (MAHLE-STIFTUNG GmbH)
• Original Assignee: Mahle International GmbH (MAHLE-STIFTUNG GmbH)
• Inventors: Scharp, Rainer, Keller, Klaus
• Granted Patent: US 8,635,982 B2
• Time in Patent Office: Days
• US Class Current: 123/193.6
• CPC Class Codes: B23K 20/129 specially adapted for particular articles or workpieces
• CPC Class Codes: B23K 2101/003 Pistons
• CPC Class Codes: C21D 9/0068 for particular articles not mentioned below
• CPC Class Codes: C21D 9/50 for welded joints
• CPC Class Codes: F02F 2003/0061 by welding
• CPC Class Codes: F02F 3/003 the parts being connected by casting, brazing, welding or clamping
• CPC Class Codes: F02F 3/0092 the material being steel-plate
• CPC Class Codes: F02F 3/22 the fluid being liquid
• CPC Class Codes: Y10T 29/49252 Multi-element piston making
• CPC Class Codes: Y10T 29/49254 Utilizing a high energy beam, e.g., laser, electron beam

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.

Claims

1. 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 tempered steel or a precipitation-hardened steel, having at least one joining surface (29, 31),

(b) making available a blank (212′

) of the second piston component (12, 112, 212) composed of a tempered steel or a precipitation-hardened steel, having at least one joining surface (32, 33),

(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),

(e) annealing or low-stress annealing of the piston blank (210′

), thereby obtaining the heat influence zone(s) (30, 30′

),

(f) re-machining and/or finishing the piston blank (210′

) to produce a piston (10, 110, 210).

2. Method according to claim 1, wherein the blanks (211′

, 212′

) are pre-machined between step (c) and step (d).

3. Method according to claim 1, wherein the at least one friction-welding seam (26, 125) is configured in such a manner that it runs at an acute angle (α

) or an obtuse angle (β

) relative to the piston center axis (A), in the radial direction.

4. Method according to claim 1, 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 the friction-welding seam.

5. Method according to claim 1, wherein in step (f), 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) is less than the axial height of the heat influence zone (30) of this friction-welding seam (25).

6. Method according to claim 1, wherein in step (a), a blank (211′

) of a piston base body (11, 111, 211) having an outer joining surface (29) and an inner joining surface (31) as well as a circumferential lower cooling channel part (23a) between the two joining surfaces (29, 31) is made available, and wherein in step (b), a blank (212′

) of a piston ring element (12, 112, 212) having an outer joining surface (32) and an inner joining surface (33) as well as a circumferential upper cooling channel part (23b) between the two joining surfaces (32, 33) is made available.

7. Method according to claim 6, wherein a blank (212′

) of a piston ring element (12, 112, 212) that has a combustion chamber bowl (24) is used.

8. Method according to claim 6, wherein a blank (12′

) of a piston ring element (12, 112, 212) that has at least one wall region (28′

) of a combustion chamber bowl (24) is used, and wherein a blank (211′

) of a piston base body (11, 111, 211) that has at least one crown region (27) of a combustion chamber bowl (24) is used.

9. Piston (10, 110, 210) that can be produced according to claim 1.

10. 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, and wherein the at least one friction-welding seam (25, 26, 125, 226) is surrounded by a heat influence zone (30, 30′

).

11. Piston according to claim 10, wherein the at least one friction-welding seam (26, 125) is configured in such a manner that it runs perpendicular to or at an acute angle (α

) or at an obtuse angle (β

) relative to the piston center axis (A).

12. Piston according to claim 10, wherein the at least one friction-welding seam (25, 125) 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 the friction-welding seam (25, 125).

13. Piston according to claim 10, wherein the first piston component is a piston base body (11, 111, 211) that has at least one piston skirt (15), wherein the second piston component is a piston ring element (12, 112, 212) that has at least a piston crown (19), a circumferential top land (21), and a circumferential ring belt (22) provided with ring grooves (34, 36, 37), and wherein the piston base body (11) and the piston ring element (12) form a circumferential cooling channel (23).

14. Piston according to claim 12, wherein the piston ring element (12) has a combustion chamber bowl (24).

15. Piston according to claim 12, wherein the piston ring element (12, 112, 212) has at least one wall region (28′

) of a combustion chamber bowl (24), and wherein the piston base body (11, 111, 211) has at least one crown region (27) of a combustion chamber bowl (24).