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
  • C23C8/02—Pretreatment of the material to be coated
• • 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
  • C23C8/80—After-treatment
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J9/00—Piston-rings, e.g. non-metallic piston-rings, seats therefor; Ring sealings of similar construction
  • F16J9/26—Piston-rings, e.g. non-metallic piston-rings, seats therefor; Ring sealings of similar construction characterised by the use of particular materials
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49229—Prime mover or fluid pump making
  • Y10T29/49274—Piston ring or piston packing making

Definitions

• the present invention relates to a method for producing a piston ring for internal combustion engines and such a piston ring.
• Piston rings of trapezoidal cross-section in which the ring height is greater on the outer peripheral surface than on the inner peripheral surface, are also referred to as trapezoidal rings.
• a piston ring in which a ring flank is formed parallel to the inner and outer peripheral surfaces while the other ring flank extends at an angle thereto is referred to as a (simple) trapezoidal ring.
• a piston ring, in which both ring flanks extend at an angle to the peripheral surfaces, is called a double trapezoidal ring.
• Such piston rings are preferably used in diesel engines as the top piston ring (top ring), wherein the associated piston ring groove is also formed trapezoidal.
• diesel engines tend to deposit hard carbonaceous residues in the uppermost Kolbenringnut, which can lead to a festging of the piston rings and thus to functional failures. Due to the trapezoidal design of the uppermost piston ring and its kingpin groove, the festival is usually prevented and thus ensures the sealing function of the piston ring.
• European published patent application EP 0 605 223 A1 describes a piston ring whose surface has been hardened by gas nitriding. On the later running surface, a metal nitride layer is applied over the gas nitriding layer as a tribological layer.
• German Offenlegungsschrift DE 102 07 148 A1 also describes a piston ring with a nitriding layer composed of a diffusion layer and a connecting layer, a deposit layer of hard ceramic being provided on the later running surface after removal of the diffusion layer.
• the trapezoidal rings or double trapezoidal rings produced in this way exhibit increased fretting damage (so-called “fretting") on the ring flanks, with additional coking being detectable, in particular at high ignition pressures of 200 bar to 220 bar with the running time of the piston rings and eventually lead to their failure. It has also been found that these damages can be location-dependent, that is, that they can vary greatly along the circumference of the ring flanks. Especially at those points where the nitriding layer was removed, these damages occur frequently.
• the present invention is therefore based on the object to provide a method for producing a piston ring and such a piston ring, with which the occurrence of ring flank damage to trapezoidal rings or double trapezoidal rings during engine operation is largely prevented.
• the piston ring according to the invention whose surface forms an inner and an outer peripheral surface and an upper and a lower annular edge, is characterized in that the surface is provided with a uniformly thick hardened layer.
• Trapezoidal rings or double trapezoidal rings with wear-resistant ring flanks are provided by the method according to the invention, which have significantly reduced fretting damage during engine operation (so-called “fretting") the hardening pro- Z ⁇ SS, it is possible to produce a uniform hardened layer with uniform depth on the ring flanks of the trapezoidal ring or double trapezoidal ring. This uniformly high hardness values are obtained so that along the circumference of the ring edges substantially no Reibverschl employ2020 impairing the piston ring function impairing occur. Likewise, micro welds between piston ring and piston are effectively prevented.
• a steel strip with a rectangular cross-section is used as a base material for the piston ring according to the invention.
• This steel strip is preferably made of martensitic steel with a content of 12 to 17 wt .-% chromium. If a nitriding process is chosen to cure the surfaces, a nitriding zone is formed in which hard chromium nitrides are additionally embedded.
• the metal strip is, for example, converted by cutting or non-cutting machining into a trapezoidal cross-section, preferably by grinding, for example.
• the machined surface or the machined surfaces should later form the ring flank or ring flanks of the piston ring to be produced. It is advantageous if, in addition to the beveled surface (s), regions which continue to run parallel to each other are also retained.
• the width of the mutually parallel regions is preferably at most a quarter of the total width of the steel strip.
• the parallel areas can serve as stacking surfaces for packaging the trapezoidal rings or double trapezoidal rings in the later processing of the piston ring.
• both an endless metal strip and a blank can be used and processed to obtain the at least one beveled surface.
• the machining can be done in a continuous process.
• trapezoidal in cross-section metal band becomes a Molded piston ring, optionally separated to the required length, if an endless metal strip is used, and then the further processing, in particular a mechanical processing, for example, the surfaces and / or a heat treatment subjected.
• a wear protection layer preferably a chromium layer or a chromium nitride layer, can additionally be applied to the lower ring flanks of the piston ring, since experience has shown that the lower ring flanks are subjected to particularly high stress.
• an additional wear protection layer or tribological layer may be applied to the outer circumferential surface or tread of the piston ring to increase the life of the trapezoidal rings or double trapezoidal rings.
• the trapezoidal rings or double trapezoidal rings are preferably stacked under axial bias to form a package. This avoids that the ring flanks are coated with the wear protection layer, if this is not desired.
• Fig. 1 is a schematic representation of the manufacturing process for a double trapezoidal ring according to the prior art
• FIG. 2 shows a schematic representation of a double trapezoidal ring produced by the method according to the invention
• FIG. 3 is a schematic representation of the manufacturing process for a double trapezoidal ring according to the invention
• Fig. 4 is an illustration of the location-dependent Reibverschl composeJden on the ring flanks of a double trapezoidal ring according to the prior art on the one hand and according to the invention on the other.
• Fig. 1 shows again the production of a piston ring 30 of a trapezoidal ring according to the prior art.
• a piston ring 30 is formed in a conventional manner.
• surface hardening typically nitriding
• a hardened layer 21 in this case a nitriding layer of a diffusion layer and a connecting layer, forms along the surface of the piston ring 30.
• the outer peripheral surface is provided with a wear-resistant layer 32 (not shown).
• the piston rings 30 are preferably stacked under axial bias to form a package. This avoids that the ring flanks are coated with the wear protection layer, as this is not usually desired.
• the piston ring 30 is machined to give it the desired shape of a trapezoidal ring or double trapezoidal ring.
• the ring flanks are at least partially ground at a shallow angle, so that beveled upper and lower annular edges 35, 36 are formed, followed by the parallel upper and lower portions 33, 34.
• the outer peripheral surface 32 and the inner peripheral surface 31 of the piston ring 30 remain.
• the hardened layer 21 is at least partially removed along the upper and lower ring flanks.
• Fig. 2 shows schematically a double trapezoidal ring 10, which is produced by the method according to the invention, as shown schematically in Figure 3. Again, the following explanations apply equally to a trapezoidal ring.
• the starting material is, for example, as shown in FIG.
• Tensitic steel strip 20 (chromium content 12 to 17 wt .-%) with a rectangular cross-section.
• This steel strip 20, which may be an endless steel strip or a blank, is converted in a first operation into a trapezoidal cross-section.
• a suitable method is the grinding of the upper and lower broad sides of the steel strip 20.
• the steel strip can also be formed by cold rolling the broad sides into a trapezoidal cross-section.
• beveled surfaces 15, 16 and a higher narrow side 12 and a lower narrow side 11 are formed with mutually parallel surfaces 13, 14 are maintained, which adjoin the beveled surfaces 15, 16 and the higher narrow side 12.
• the mutually parallel surfaces 13, 14 are used in the exemplary embodiment, the stackability of the piston rings, which is advantageous in some of the subsequent processing steps to ensure.
• Their width is, for example, up to a quarter, preferably less than a quarter of the width of the steel strip 20th
• the steel strip 20 thus processed is formed in a conventional manner by suitable devices to a piston ring 10 and possibly cut off, the higher narrow side of the steel strip 20 in the outer peripheral surface 12 and the lower narrow side of the steel strip 20 in the inner peripheral surface 11 of Piston ring 10 is transferred.
• the surfaces 13, 15 form the upper annular edge and the surfaces 14, 16, the lower annular edge of the piston ring 10th
• the piston ring 10 thus has a trapezoidal cross-section already after this production step.
• the piston ring 10 is subjected to a hardening process.
• the piston ring 10 by means of a per se known Gasnitrierpro- nitrided over its entire surface, so that a circumferential nitriding layer 21 results, which consists in the embodiment of a diffusion layer and a connecting layer, wherein the Nitrierhärtiefe can be up to 200 microns in the diffusion layer.
• the bonding layer has , for example, a Vickers hardness 700 HVO, 05 at a layer thickness of about 5 to 10 ⁇ m. If the steel strip 20 contains chromium, hard chromium nitrides are formed during nitriding.
• the bonding layer is separated from the surface of the piston ring 10, i. From the outer peripheral surface and from the annular edges of the piston ring 10, for example. Removed by grinding.
• the desired piston ring 10 is present, in the embodiment in the form of a double trapezoidal ring.
• a chromium or chromium nitride preferably be applied to the lower ring flank with the surfaces 14, 16, as there especially in the trapezoidal rings produced according to the prior art there Reibverschl devisden have shown.
• a wear protection layer or tribological layer is applied on the outer peripheral surface 12, which corresponds to the later running surface of the piston ring 10, if necessary.
• a wear protection layer or tribological layer is applied on the outer peripheral surface 12, which corresponds to the later running surface of the piston ring 10, if necessary.
• a wear protection layer or tribological layer is applied on the outer peripheral surface 12, which corresponds to the later running surface of the piston ring 10, if necessary.
• a wear protection layer or tribological layer is applied on the outer peripheral surface 12, which corresponds to the later running surface of the piston ring 10.
• a wear protection layer or tribological layer is applied on the outer peripheral surface 12, which corresponds to the later running surface of the piston ring 10.
• a wear protection layer or tribological layer is applied on the outer peripheral surface 12, which corresponds to the later running surface of the piston ring 10.
• a wear protection layer or tribological layer is applied on the outer peripheral surface 12, which corresponds to the later running surface of the piston ring
• a galvanic hard chrome layer or a thermal spray layer or a manganese phosphate layer may also be applied to the outer peripheral surface 12.
• the coating of the outer circumferential surface 12 and later running surface of the piston ring 10 is expediently carried out in the stacked and axially braced state of a plurality of piston rings 10. In particular, this ensures that the surfaces 13, 14, 15, 16 of the annular edges during the coating process not with the applied wear protection layer or be coated tribological layer.
• FIG. 4 shows a representation of the local peripheral frictional wear damage for a 6-cylinder diesel engine with a running time of 100 hours under full load, on the one hand for a piston ring according to the prior art, on the one hand for a piston ring 10 produced according to the invention in the form of a double trapezoidal ring. It can be seen from the graph that the piston ring 10 produced according to the invention shows significantly less fretting damage on the ring flanks compared with the prior art.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Pistons, Piston Rings, And Cylinders (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=37527760

Family Applications (1)

Country Status (8)

Cited By (1)

Families Citing this family (19)

Family Cites Families (23)

• 2005
  • 2005-09-01 DE DE102005041408A patent/DE102005041408A1/de not_active Withdrawn
• 2006
  • 2006-08-31 RU RU2008111969/06A patent/RU2008111969A/ru not_active Application Discontinuation
  • 2006-08-31 BR BRPI0615327-5A patent/BRPI0615327A2/pt not_active IP Right Cessation
  • 2006-08-31 JP JP2008528337A patent/JP2009507160A/ja active Pending
  • 2006-08-31 WO PCT/DE2006/001531 patent/WO2007025533A1/de active Application Filing
  • 2006-08-31 EP EP06791337A patent/EP1920175A1/de not_active Withdrawn
  • 2006-08-31 CN CNA200680032167XA patent/CN101253353A/zh active Pending
  • 2006-08-31 US US11/991,239 patent/US20080256794A1/en not_active Abandoned

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events