METHOD FOR PRODUCING A PISTON FOR AN INTERNAL COMBUSTION ENGINE AND PISTON PRODUCED BY SAID METHOD

• US 20160281637A1
• Filed: 03/18/2014
• Published: 09/29/2016
• Est. Priority Date: 03/18/2013
• Status: Active Grant

• Current Assignee: Mahle International GmbH (MAHLE-STIFTUNG GmbH)
• Original Assignee: Mahle International GmbH (MAHLE-STIFTUNG GmbH)
• Inventors: Berr, Gerhard, Boczek, Sascha-Oliver, Mueller, Reiner, Scharp, Rainer
• Granted Patent: US 10,077,738 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B21K 1/18 pistons or plungers
• CPC Class Codes: B21K 1/185 with cooling channels
• CPC Class Codes: B23B 2215/245 Pistons
• CPC Class Codes: B23K 15/0053 Seam welding
• CPC Class Codes: B23K 15/0093 characterised by the properties of the materials to be welded
• CPC Class Codes: B23K 2101/003 Pistons
• CPC Class Codes: B23K 2103/04 Steel or steel alloys
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/282 of tube sections
• CPC Class Codes: B23K 26/32 taking account of the properties of the material involved
• CPC Class Codes: B23P 15/10 pistons
• CPC Class Codes: F02F 2003/0061 by welding
• CPC Class Codes: F02F 2200/04 Forging of engine parts
• CPC Class Codes: F02F 3/003 the parts being connected by casting, brazing, welding or clamping
• CPC Class Codes: F02F 3/22 the fluid being liquid
• CPC Class Codes: F02F 3/28 Other pistons with specially-shaped head

Abstract

A method for producing a piston for an internal combustion engine may include the steps of: producing a piston main body from a first blank via a deformation process; producing a piston ring part from a second blank via at least one of a deformation process and a casting process; pre-machining the first blank and the second blank, and finish machining a welding surface of the first blank and a welding surface of the second blank; connecting the pre-machined first blank and the pre-machined second blank via a welding process to form a piston body; and performing at least one of a secondary machining and a finish machining of the piston body to produce the piston.

Claims

1. A method for producing a piston for an internal combustion engine, comprising the steps of:

a) producing a piston main body from a first blank via a deformation process, wherein the piston main body includes a combustion depression having a dome, a plurality of piston bosses together defining at least two boss bores, the plurality of piston bosses connected to one another view a running surface, and wherein the combustion depression includes a welding surface radially on an outside with respect to a piston central axis;

b) producing a piston ring part from a second blank via at least one of a deformation process and a casting process, wherein the piston ring part includes a piston crown, an annular fire land and an annular ring section, and wherein the piston crown has a welding surface radially on an inside with respect to the piston central axis;

c) pre-machining the first blanks and the second blank, and finish machining the welding surfaces of the combustion depression and the piston crown;

d) connecting the pre-machined first blanks of piston main body and the pre-machined second blank of the piston ring part via a welding process to form a piston body, wherein the piston main body and the piston ring part together define an annular cooling duct; and

e) performing at least one of a secondary machining and a finish machining of the piston body to produce the finished piston;

wherein during step a), a contour of the combustion depression outside of a dome region is formed to completion, and an excess material deposit is disposed in the dome region of the combustion depression, and wherein step e), further includes removing an amount of the excess material deposit in the dome region of the combustion depression to define a predetermined volume of the combustion depression.

2. The method as claimed in claim 1, wherein step e) further includes inspecting the predetermined volume of the combustion depression, during the removal of the excess material deposit in the dome region, wherein inspecting the predetermined volume includes determining a lowest point of the combustion depression, and establishing a starting point for a finish machining of the piston crown based on a plane running perpendicularly to the piston central axis and extending through the lowest point.

3. The method as claimed in claim 1, wherein step c) further includes forming a first cooling duct region into the first blanks and forming a second cooling duct region into the second blank.

4. The method as claimed in claim 1, wherein step c) further includes finish machining an interior space defined in the first blank of the piston main body and forming an inlet opening and an outlet opening for a cooling fluid into a cooling duct region of the first blank.

5. The method as claimed in claim 1, wherein step c) further includes pre-machining an outer diameter of at least one of the first blank of the piston main body and the second blank of the piston ring part.

6. The method as claimed in claim 1, wherein step e) further includes forming the at least two boss bores into the plurality piston bosses after performing the finish machining of at least the piston crown.

7. The method as claimed in claim 1, wherein step a) further includes forging the first blank of the piston main body via hot working at a temperature ranging from 1200°

C. to 1300°

C. and subsequently performing a cold calibration process to the first blank.

8. The method as claimed in claim 1, wherein step a) further includes forging the first blank of the piston main body via hot working at a temperature ranging from 1200°

C. to 1300°

C. and subsequently cold working the first blank at a temperature of 150°

C. or less.

9. The method as claimed in claim 1, wherein step a) further includes forging the first blank of the piston main body via warm working at a temperature ranging from 600°

C. to 900°

C.

10. The method as claimed in claim 9, further comprising cold working the first blank of the piston main body at a temperature of 150°

C. or less after warm working the first blank.

11. The method as claimed in claim 1, wherein step a) further includes forging the first blank of the piston main body via cold working at a temperature of 150°

C. or less.

12. A piston for an internal combustion engine produced according to the method of claim 1.

13. The piston as claimed in claim 12, wherein the combustion depression is at least one of configured asymmetrical with respect to the piston central axis, arranged radially offset with respect to the piston central axis and configured inclined with respect to the piston central axis.

14. The method as claimed in claim 1, wherein step a) further includes forming the combustion depression asymmetrical with respect to the piston central axis.

15. The method as claimed in claim 1, wherein step a) further includes forming the combustion depression radially offset with respect to the piston central axis.

16. The method as claimed in claim 1, wherein step a) further includes forming the combustion depression inclined with respect to the piston central axis.

17. The method as claimed in claim 1, wherein step c) further includes at least one of pre-machining and finish machining the piston crown on the second blank of the piston ring part.

18. The method as claimed in claim 1, wherein step c) further includes pre-machining the plurality of piston bosses on the first blank of the piston main body.

19. The method as claimed in claim 3, wherein step c) further includes performing a finish machining on at least one of the first cooling duct region and the second cooling duct region.

20. The method as claimed in claim 3, wherein the welding surface of the combustion depression is formed in the first cooling duct region and the welding surface of the piston crown is formed in the second cooling duct region.