EP0985739B1 - Procédé pour le durcissement de têtes de piston et tête de piston - Google Patents

Procédé pour le durcissement de têtes de piston et tête de piston Download PDF

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Publication number
EP0985739B1
EP0985739B1 EP19980117125 EP98117125A EP0985739B1 EP 0985739 B1 EP0985739 B1 EP 0985739B1 EP 19980117125 EP19980117125 EP 19980117125 EP 98117125 A EP98117125 A EP 98117125A EP 0985739 B1 EP0985739 B1 EP 0985739B1
Authority
EP
European Patent Office
Prior art keywords
piston
crown
zone
hardening
piston crown
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19980117125
Other languages
German (de)
English (en)
Other versions
EP0985739A1 (fr
Inventor
Reinke Horst
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
MMS Marine Motor Service
Original Assignee
MMS Marine Motor Service
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by MMS Marine Motor Service filed Critical MMS Marine Motor Service
Priority to EP19980117125 priority Critical patent/EP0985739B1/fr
Priority to DE59808370T priority patent/DE59808370D1/de
Publication of EP0985739A1 publication Critical patent/EP0985739A1/fr
Application granted granted Critical
Publication of EP0985739B1 publication Critical patent/EP0985739B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/24—Nitriding
    • C23C8/26—Nitriding of ferrous surfaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B3/00—Engines characterised by air compression and subsequent fuel addition
    • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F7/00—Casings, e.g. crankcases or frames
    • F02F2007/0097—Casings, e.g. crankcases or frames for large diesel engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2201/00—Metals
    • F05C2201/04—Heavy metals
    • F05C2201/0433—Iron group; Ferrous alloys, e.g. steel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2201/00—Metals
    • F05C2201/04—Heavy metals
    • F05C2201/0433—Iron group; Ferrous alloys, e.g. steel
    • F05C2201/0448—Steel

Definitions

  • the invention relates to a method for hardening at least a portion of the surface of steel piston crowns and a steel piston crown, in particular for Large diesel engines.
  • Piston systems are essential components of large diesel engines, such as those be used in the type of ship and in the power plant industry. Because of that too Large piston engines are getting ever stricter emission limits of paramount importance, since here with regard to temperature stress, force and wear extreme conditions prevail. Pistons of modern high-performance diesel engines therefore consist mainly of several components around the to take different requirements into account.
  • the piston crown, the top one, the Combustion chamber represents opposite element and the whole Passes through the combustion process, forms the most vulnerable part in such System.
  • Piston crowns are made of a special steel and are usually exchangeable after reaching the wear limit.
  • Piston crowns and especially theirs are used to extend the service life Piston ring grooves hardened, either inductively or by chrome plating.
  • the inductive Hardening results in medium wear behavior, while chrome plating is quite good Wear behavior results.
  • chrome plating is now widely used, although not everywhere due to cost reasons, there are still some principle-related ones Disadvantages with regard to the manufacture and durability of a chrome plating (for example chrome layers tend to flake off).
  • DE2144238 describes a method for hardening steel components of explosion engines due to an electrical glow discharge in which no reworking of the part is required. It is cited that conventional nitriding processes always involve a change in size cause the component so that regrinding is required and that regrinding can be circumvented by undersizing or profile correction.
  • EP0007661 discloses hardening support surfaces of piston crowns, e.g. by nitriding.
  • JP09170489 describes a piston in its entirety or also in part a "soft nitride treatment" is hardened. Post-processing is not carried out.
  • the object of the invention is to provide a method for hardening the surface of Piston crowns made of steel, in particular for large diesel engines, which a optimal wear behavior with minimal manufacturing effort allowed.
  • Nitriding as such is a well-known technical process for hardening metals on the surface and thereby improving wear behavior.
  • the process according to the invention is clearly superior to all previous processes, both in technical and in terms of cost.
  • the nitriding not only leads to increased wear resistance in the groove area, but also results in a higher resistance to hot corrosion and pitting (hole formation due to micro-movements).
  • the following comparison shows that nitriding has brought about decisive improvements that are not limited to the groove area, but at the same time have brought about greater resistance in both the mechanical and chemical sectors.
  • nitriding is carried out in a nitrogen atmosphere.
  • the pore hem preferably has a hardness of 58 to 60 Rockwell.
  • the connection zone has preferably a hardness of 78 to 82 Rockwell, and the diffusion zone preferably one Hardness from 60 to 65 Rockwell.
  • the invention also relates to a piston crown made of steel, in particular for Large diesel engines, according to claim 3.
  • the surface is preferably hardened in a nitrogen atmosphere.
  • the pore hem can have a hardness of 58 to 60 Rockwell, the connection zone a hardness of 78 to 82 Rockwell and the diffusion zone have a hardness of 60 to 65 Rockwell.
  • Fig. 1 shows in a highly schematic manner in half section one designated overall by 1 Piston, whose area facing the combustion chamber is formed by a piston crown 2 which is shown with solid lines.
  • the piston crown 2 is on its outer surface interacting with the cylinder running surface provided with a row (three in the present example) piston ring grooves 3, which in known Way to accommodate piston rings.
  • the piston rings to be used show both in relation to the respective groove base (i.e. in the radial direction) as well a certain amount of play in relation to the groove side surfaces (i.e. in the axial direction).
  • Level mating surfaces 4 serve to connect the Piston crown 2 with the remaining part of the piston 1 and in particular for transferring the considerable axial forces during the combustion phase. Because of the Large diesel engines are used in high compression ratios mentioned mating surfaces next to the piston ring grooves the most mechanical Surfaces of the piston crown 2 exposed to wear.
  • Fig. 2 shows a 6.5-fold enlarged representation of the nitrided according to the invention Structure in the area of the piston ring grooves.
  • the free cross section of the groove and the outside of the Piston crown lying area (top in Fig. 2) are shown in black during the Material of the piston crown in the hardened edge areas a three-layer structure reveals.
  • the diffusion zone 7 closes, in FIG. 2, as a line running on the outermost edge of the material recognizable, an edge zone 8, the structure of which will be explained in detail.
  • FIG. 3 shows a further metallographic structural representation of a device according to the invention hardened edge area of a piston crown in a hundredfold magnification, i.e. across from Fig. 2 enlarged about 15 times, the relatively light core structure 6, the relatively dark Diffusion zone 7 and the bright edge zone 8 are now clearly recognizable.
  • FIGS Micrographs shown in 500x magnification. Because of the strong The core structure is missing in FIGS. 4 and 5, while the diffusion zone 7 (respectively below) and the bright edge zone 8 above it can be clearly seen.
  • the edge zone 8 has a two-layer structure, namely, initially adjacent to the diffusion zone 7, a so-called connection zone 8a and one a slightly darker outermost zone lying above, which is referred to as pore hem 8b. Pore border 8b and connection zone 8a are also shown in Fig. 4 by an intermediate running dark line visibly demarcated from each other.
  • the brittle pore hem 8b which is up to 20 ⁇ m thick, has a hardness of approximately 58 to 60 Rockwell on.
  • the connecting zone 8a with a thickness of approximately 6 to 10 ⁇ m has a hardness of approximately 78 to 82 Rockwell.
  • the underlying diffusion zone which is a much greater thickness than has the two aforementioned zones, has a hardness of about 60 to 65 Rockwell.
  • the Diffusion zone hardness increases with increasing thickness or distance from the surface from because the effect of nitriding due to the diffusion processes that control it the depth decreases.
  • the core hardness of the piston crown material is in this example 290 HV 10.
  • the fitting surfaces 4 must be used to produce the required fit tolerances Hardness be ground.
  • the remaining surfaces of the piston crown, especially that of the Combustion chamber facing top and the outside of the cylinder wall after hardening no longer processed or sanded to increase the resistance of Pore hem and connection zone against any wear, including chemical, exploit.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)

Claims (4)

  1. Procédé de fabrication d'une tête (2) de piston réalisée en acier et durcie sur toute sa surface externe par une nitruration, lors de laquelle un bord poreux (8b), une zone de jonction (8a) et une zone de diffusion (7) sont formés, caractérisé en ce que les surfaces de contact (4), qui servent à la fixation rigide de la tête de piston avec les autres parties du piston, sont meulées après la nitruration de manière à éliminer le bord poreux (8b) et en ce que les surfaces internes des rainures (3), destinées à la réception des segments du piston, ne sont pas meulées après le durcissement.
  2. Procédé selon la revendication 1, caractérisé en ce que la nitruration se fait dans une atmosphère d'azote.
  3. Tête (2) de piston, en particulier pour les moteurs diesel de grande puissance, réalisée en acier et durcie sur toute sa surface externe par une nitruration, lors de laquelle un bord poreux (8b), une zone de jonction (8a) et une zone de diffusion (7) sont formés, caractérisée en ce que les surfaces de contact (4), qui servent à la fixation rigide de la tête de piston avec les autres parties du piston, sont meulées après la nitruration de manière à éliminer le bord poreux (8b) et en ce que les surfaces internes des rainures (3), destinées à la réception des segments du piston, ne sont pas meulées après le durcissement.
  4. Tête de piston selon la revendication 3, caractérisée en ce que la surface externe est durcie dans une atmosphère d'azote.
EP19980117125 1998-09-10 1998-09-10 Procédé pour le durcissement de têtes de piston et tête de piston Expired - Lifetime EP0985739B1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP19980117125 EP0985739B1 (fr) 1998-09-10 1998-09-10 Procédé pour le durcissement de têtes de piston et tête de piston
DE59808370T DE59808370D1 (de) 1998-09-10 1998-09-10 Verfahren zum Härten von Kolbenkronen und Kolbenkrone

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19980117125 EP0985739B1 (fr) 1998-09-10 1998-09-10 Procédé pour le durcissement de têtes de piston et tête de piston

Publications (2)

Publication Number Publication Date
EP0985739A1 EP0985739A1 (fr) 2000-03-15
EP0985739B1 true EP0985739B1 (fr) 2003-05-14

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Family Applications (1)

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EP19980117125 Expired - Lifetime EP0985739B1 (fr) 1998-09-10 1998-09-10 Procédé pour le durcissement de têtes de piston et tête de piston

Country Status (2)

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EP (1) EP0985739B1 (fr)
DE (1) DE59808370D1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10214623A1 (de) * 2002-04-02 2003-11-13 Winergy Ag Verfahren zur Behandlung von Verzahnungen
DE102010033881A1 (de) 2010-08-10 2012-02-16 Mahle International Gmbh Kolben für einen Verbrennungsmotor und Verfahren zu seiner Herstellung

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH545859A (fr) * 1970-09-08 1974-02-15
DE2832970A1 (de) * 1978-07-27 1980-02-07 Schmidt Gmbh Karl Gebauter, fluessigkeitsgekuehlter kolben fuer brennkraftmaschinen
JPS5528379A (en) * 1978-08-23 1980-02-28 Nippon Piston Ring Co Ltd Wear resistant sliding material for internal combustion engine
DE3212338C2 (de) * 1981-04-03 1983-02-24 M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8900 Augsburg Verfahren zur Herstellung von hochbelastbaren Maschinenteilen, insbesondere Brennkraftmaschinenteilen
US4643079A (en) * 1985-03-28 1987-02-17 General Motors Corporation Iron piston having selectively hardened ring groove
JP2786873B2 (ja) * 1988-02-18 1998-08-13 三洋電機株式会社 ピストンの製造方法
JPH05148612A (ja) * 1991-11-25 1993-06-15 Nippon Piston Ring Co Ltd ピストンリングの製造方法
JP3846811B2 (ja) * 1995-12-19 2006-11-15 株式会社小松製作所 内燃機関用ピストン

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Publication number Publication date
EP0985739A1 (fr) 2000-03-15
DE59808370D1 (de) 2003-06-18

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