US3377214A - Method for hardening crankshaft - Google Patents

Method for hardening crankshaft Download PDF

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Publication number
US3377214A
US3377214A US519099A US51909966A US3377214A US 3377214 A US3377214 A US 3377214A US 519099 A US519099 A US 519099A US 51909966 A US51909966 A US 51909966A US 3377214 A US3377214 A US 3377214A
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United States
Prior art keywords
journal
hardening
crankshaft
fillet
nitriding
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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
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US519099A
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English (en)
Inventor
James O Woodbridge
Robert M Spencer
Donald D Dalrymple
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National Forge Co
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National Forge Co
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Publication date
Application filed by National Forge Co filed Critical National Forge Co
Priority to US519099A priority Critical patent/US3377214A/en
Priority to DEN27929A priority patent/DE1284981B/de
Priority to GB58058/66A priority patent/GB1107170A/en
Application granted granted Critical
Publication of US3377214A publication Critical patent/US3377214A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/30—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for crankshafts; for camshafts
    • 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
    • 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
    • Y10T74/00—Machine element or mechanism
    • Y10T74/21—Elements
    • Y10T74/2173—Cranks and wrist pins

Definitions

  • the present invention relates to the manufacture of crankshafts and more particularly to an improved method for hardening the main and pin journal surfaces to improve their wear qualities and also hardening the fillet zones located at the ends of the journal bearing surfaces where the latter merge into the web faces of the crankshaft which establish the necessary offset, or crank throws between the main and pin journals.
  • crankshafts In the construction and design of crankshafts, it has been found particularly desirable to provide fillets as distinguished from a sharp, line transition at the junctions between the journal bearing surface ends and the web faces in order to increase the fatigue strength of the crankshaft at the ends of the journals where the crankshaft is subject to its most severe stresses during operation and thereby minimize the possibility of fractures and operational crankshaft failure at these locations.
  • the surfaces of the main and pin journals are, of course, subjected to severe wear conditions especially when the crankshaft is operating under a heavy load and, to retard this wear, it has also long been conventional to harden the journal surfaces by various surface hardening techniques.
  • This hardening of the journal surfaces and fillet zones has, for example, been carried out by rapid heating of the parts to be hardened and then quenching them.
  • the heating of the parts can be effected by causing very heavy, medium frequency induced, electrical current to circulate near the surface, the current being produced by means of the well known induction process wherein properly configured inductors are fitted about the journal surfaces and fillet zones and current passed through them thus inducing the flow of a secondary or heating current in the areas to be hardened.
  • the crankshtaft may or may not be rotated during the induction hardening cycle. When the parts have reached the proper temperature, the current is interrupted and the parts immediately quenched thus completing the hardening technique.
  • journal surfaces themselves are not too difficult, it is quite difiicult to maintain a uniform pattern of hardening in the fillet zones due to the difficulty in configuring the inductors themselves at these zones such that the flow of induced current conforms to the desired uniform hardening pattern in the fillet zones. Straightening after treatment becomes extremely difficult.
  • nitriding Another technique in common use for hardening of the bearing surfaces and fillet zones of crankshafts is that of nitriding.
  • One common nitriding practice is a process wherein the crankshaft is placed within a sealed bell, or some other suitable furnace enclosure, and those parts of the crankshaft desired to be hardened are exposed to anhydrous ammonia at a temperature of from 950- l,050 F. for a prolonged period. Dissociation of the ammonia occurs and nitrides are formed in the surface layers of the journal surfaces and fillet zones.
  • the advantage of this type of hardening operation is that, due to the relatively low nitriding temperature and the absence of quenching, the hardening can be carried out with a minimum of deformation tensile stresses in the crankshaft and hence, only minor straightening is necessary after nitriding.
  • the nitrided case imparts high compressive stresses to the surface layer, because it expands in volume (also giving increased rigidity as Well as wear resistance). Since most fatigue failures start from high tensile stresses in the critical fillet zones at the very surface, the built-in compression of a nitrided layer reduces the magnitude of the tensile stresses imposed by service loadings, thus extending the fatigue life of the crankshaft.
  • crankshaft is preferably supported on end in a completely passive manner and this can be effected by means of the apparatus disclosed in U.S. Patent No. 2,803,449, issued Aug. 20, 1957, in the name of Ralph E. Ludwig.
  • Another advantage of hardening through nitriding is that ideal control over the hardening pattern in the fillet zones can be obtained, since the areas to be left unhar-dened can be blocked off effectively and economically.
  • nitriding processes One disadvantage inherent in many nitriding processes is that a considerable length of time is required in order to obtain a practical depth of hardness on the journal surfaces themselves, some processes taking upwards of hours to complete.
  • a second disadvantage of nitriding is that the depth of hardness obtained for the bearing surfaces is less than optimum, and a third disadvantage is that the nitriding process gives rise to formation of a very hard and brittle skin of iron-nitride from 0.0005" to 0.001 thick in the outermost surface layers which is commonly known as white layer, and which should first be removed by grinding or other known techniques before the crankshaft can be put into use.
  • US. Patent No. 3,069,296 describes various methods for removing or reducing white-layer.
  • Crankshafts whose journal surfaces haveubeen hardened when new can be reconditioned in various manners.
  • the worn journal bearing surfaces can be ground down until a uniformly diametered unworn base depth is reached and the journal surfaces can then be built back to their original size by chromium plating.
  • a crankshaft having induction hardened journal surfaces can be ground until a uniformly diametered unworn base depth is reachedmore flexibility is available here since the induction hardening operation reaches to a greater depth than is possible with nitriding-and the undersized journal surfaces equipped with properly sized bearings. This procedure is especially advantageous if chromiumplating facilities are not available for rebuilding the worn surfaces.
  • crankshaft whose journal surfaces and fillets have been hardened by induction heating and quenching has .certain advantages as well as disadvantages-and this is likewise true as regards hardening by nitriding.
  • the object of the present invention is to provide a hardening technique for the journal surfaces and fillet zones of crankshafts which enjoys the advantages of both processes without, however, entailing their disadvantages.
  • the improved hardening technique includes an initial hardening by nitriding of the journal surfaces and fillet zones of the crankshaft in one and the same nitriding operation until one obtains a depth of hardness in the fillet zones suflicient to achieve a desired increase in the fatigue strength of the crankshaft in the critical fillet zones.
  • the hardened fillets will resist cracking and failure of the crankshaft while under loads.
  • journal surfaces of the crankshaft are subjected to a further hardening treatment involving a quick reheating of such surfaces, such as, for example, by induction, followed by quenching so as to not only increase the hardness accomplished through nitriding but also increase the depth of the hardened case on the journal surfaces.
  • FIG. 1 shows a portion of a crankshaft partly in section and partly in elevation
  • FIG. 2 is a graph in which hardness is plotted against depth for the journal portions of the crankshaft for various hardening techniques including the one constituting the inventive concept.
  • crankshaft is indicated generally at 1 and is provided with a plurality of main journals 2 and pin journals 3 which are axially off set from the main journals 2 by web face 4.
  • the transition is preferably accomplished by machining fillets of a generous radius 5 rather than leave a sharp line at the transit-ion point.
  • such fillets are desirable to increase the fatigue strength of the crankshaft at these most critical zones where the shaft is subjected to its most severe stresses during operation, and where most crankshaft failures have been found to occur.
  • crankshaft itself can be made from any conventional nitridable steels now in use for this purpose, a typical steel being of the A151. 4130 or 4140 grades.
  • an initial hardening of the fillet zones and of the main and pin journal surfaces is accomplished by a nitriding operation.
  • This nitr-iding step can be carried out in a conventional manner, for example, with apparatus of the type described in the above mentioned Ludwig Patent No. 2,803,449 in which the crankshaft is supported on end, to minimize distortion and deformation stresses during the heating cycle.
  • the nitriding is carried out at a temperature of from 950l050 F. and is continued for such time as will establish a nitride-hardened case of a depth sufficient to provide the desired compressive stresses and resulting increase in fatigue strength in the critical fillet zones.
  • the main and pin journal surfaces 2 and 3 are, of course, likewise hardened but these surfaces have at least some white layer content at the skin, and are of less than optimum depth at this point of the hardening procedure.
  • a typical depth and pattern of the nitrided parts below the surface of the crankshaft is designated by the dashed lines.
  • further hardening of the main and pin journals is now accomplished by subjecting only the nitrided portions of the main and pin journals 2 and 3 exclusive of the fillet areas to a subsequent hardening step which involves a quick heating of only the main and pin journal surfaces to a temperature within the austenitizing range for the steel followed by quenching until a temper-tune is reached such that substantially all of the austenite in the nitrided portions of the journal surfaces is transformed in nitrogen-bearing martensite.
  • the necessary quick-heating of the ni-trided main and pin journal surfaces can be accomplished in any suitable manner but induction type heating is probably the most practical since the zone to be heated, i.e. the journal surfaces but not the fillets, is more easily controllable by design of the inductors which are fitted about the journal surfaces.
  • the second stage of the hardening operation which has been done, using a frequency of 3,000 cycles/sec. increases the depth of hardness initially effected by nitriding, and a typical depth and pattern of the additional hardening accomplished in the main and pin journals is indicated by the dash-dot lines. It will be understood that the depths of dash-dot lines as Well as the dash lines as shown in the drawings are not to scale but have been exaggerated to show clearly on the drawing. Moreover, in addition to an increase in the depth of hardness, the hardness of the steel itself, e.g. A.I.S.I. 413i) is increased to a value higher than that which is usually obtained by conventional induction hardening technique for this same steel as shown in the comparative graphs of FIG. 2.
  • crankshafts in accordance with the invention produces a superior crankshaft which will be better able to withstand service stresses and overloads for a longer period of time without failure compared to a standard equivalent induction hardened crankshaft.
  • the hardening operation itself of the journal surfaces and of the fillet zones is more desirable since one is able to reduce, if not eliminate altogether, creation of dangerously high deformation tensile stresses in the critical fillet zones found in induction hardened crankshafts which not only increase the danger of forming surface fissures in these zones but also lead to actual deformation in the shaft itself which then necessitates a straightening operation and the creation of further undesirable stress conditions in the str'anghtened shaft.
  • journal surfaces themselves can be hardened to a greater depth and to a higher degree of hardness not heretofore obtainable with use of either nitriding or induction hardening procedures alone.
  • the undesirable white layer characteristic previously inherent in nitriding operations is actually eliminated in the journal areas as a result of the second hardening operation.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Heat Treatment Of Articles (AREA)
  • Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)
US519099A 1966-01-06 1966-01-06 Method for hardening crankshaft Expired - Lifetime US3377214A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US519099A US3377214A (en) 1966-01-06 1966-01-06 Method for hardening crankshaft
DEN27929A DE1284981B (de) 1966-01-06 1966-01-21 Verfahren zum Oberflaechenhaerten von staehlernen Kurbelwellen
GB58058/66A GB1107170A (en) 1966-01-06 1966-12-29 Method for hardening crankshaft

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DE (1) DE1284981B (de)
GB (1) GB1107170A (de)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3880600A (en) * 1972-04-20 1975-04-29 Bbc Brown Boveri & Cie Self-lubricating slide element
US4043847A (en) * 1974-11-22 1977-08-23 Motoren- Und Turbinen-Union Friedrichshafen Gmbh Hardening process for crankshafts
US4173501A (en) * 1978-06-01 1979-11-06 Clark Equipment Company Steel torsional element and method for making
US4236942A (en) * 1977-05-31 1980-12-02 British Leyland Uk Limited Method for the gaseous nitriding of ferrous-based components
US4599502A (en) * 1983-11-22 1986-07-08 National Forge Company Induction hardening of steel
US4637310A (en) * 1983-05-09 1987-01-20 Tokyo Kikai Seusakusho Ltd. Mesh roller for printing press and method of fabrication
US4656723A (en) * 1984-06-11 1987-04-14 Kioritz Corporation Method of forming screw thread on crankshaft and the like
US4874437A (en) * 1989-02-08 1989-10-17 Kioritz Corporation Method of adjusting hardness of metallic material
US5001917A (en) * 1987-07-13 1991-03-26 W. Hegenscheidt Gesellschaft Mbh Method and apparatus for truing or straightening out of true work pieces
US5235838A (en) * 1987-07-13 1993-08-17 W. Hegenscheidt Gesellschaft Mbh Method and apparatus for truing or straightening out of true work pieces
US5426998A (en) * 1990-11-20 1995-06-27 Daidousanso Co., Ltd. Crank shaft and method of manufacturing the same
US5561908A (en) * 1991-11-06 1996-10-08 Sandvik Ab Chainsaw guide bar
US5596811A (en) * 1995-04-25 1997-01-28 Sandvik Ab Chainsaw guide bar
US20080229877A1 (en) * 2007-03-23 2008-09-25 Yamaha Hatsudoki Kabushiki Kaisha Crankshaft, internal combustion engine, transportation apparatus, and production method for crankshaft
US20140260787A1 (en) * 2013-03-18 2014-09-18 Electro-Motive Diesel, Inc. Selectively strengthened crankshaft
WO2017119224A1 (ja) * 2016-01-08 2017-07-13 株式会社神戸製鋼所 大型クランク軸
US11491541B2 (en) 2019-05-31 2022-11-08 Apollo Machine & Welding Ltd. Hybrid process for enhanced surface hardening

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2803449A (en) * 1953-10-21 1957-08-20 Nat Forge & Ordnance Company Apparatus for nitriding crankshafts
US3108913A (en) * 1961-03-16 1963-10-29 Ohio Crankshaft Co Crankshafts and method of hardening same
US3216869A (en) * 1960-06-21 1965-11-09 Gen Motors Corp Method of heat treating steel
US3257865A (en) * 1962-04-19 1966-06-28 Deutsche Edelstahlwerke Ag Crankshafts

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2803449A (en) * 1953-10-21 1957-08-20 Nat Forge & Ordnance Company Apparatus for nitriding crankshafts
US3216869A (en) * 1960-06-21 1965-11-09 Gen Motors Corp Method of heat treating steel
US3108913A (en) * 1961-03-16 1963-10-29 Ohio Crankshaft Co Crankshafts and method of hardening same
US3257865A (en) * 1962-04-19 1966-06-28 Deutsche Edelstahlwerke Ag Crankshafts

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3880600A (en) * 1972-04-20 1975-04-29 Bbc Brown Boveri & Cie Self-lubricating slide element
US4043847A (en) * 1974-11-22 1977-08-23 Motoren- Und Turbinen-Union Friedrichshafen Gmbh Hardening process for crankshafts
US4236942A (en) * 1977-05-31 1980-12-02 British Leyland Uk Limited Method for the gaseous nitriding of ferrous-based components
US4173501A (en) * 1978-06-01 1979-11-06 Clark Equipment Company Steel torsional element and method for making
US4637310A (en) * 1983-05-09 1987-01-20 Tokyo Kikai Seusakusho Ltd. Mesh roller for printing press and method of fabrication
US4599502A (en) * 1983-11-22 1986-07-08 National Forge Company Induction hardening of steel
US4656723A (en) * 1984-06-11 1987-04-14 Kioritz Corporation Method of forming screw thread on crankshaft and the like
US5001917A (en) * 1987-07-13 1991-03-26 W. Hegenscheidt Gesellschaft Mbh Method and apparatus for truing or straightening out of true work pieces
US5235838A (en) * 1987-07-13 1993-08-17 W. Hegenscheidt Gesellschaft Mbh Method and apparatus for truing or straightening out of true work pieces
US4874437A (en) * 1989-02-08 1989-10-17 Kioritz Corporation Method of adjusting hardness of metallic material
US5426998A (en) * 1990-11-20 1995-06-27 Daidousanso Co., Ltd. Crank shaft and method of manufacturing the same
US5561908A (en) * 1991-11-06 1996-10-08 Sandvik Ab Chainsaw guide bar
US5596811A (en) * 1995-04-25 1997-01-28 Sandvik Ab Chainsaw guide bar
US20080229877A1 (en) * 2007-03-23 2008-09-25 Yamaha Hatsudoki Kabushiki Kaisha Crankshaft, internal combustion engine, transportation apparatus, and production method for crankshaft
US20140260787A1 (en) * 2013-03-18 2014-09-18 Electro-Motive Diesel, Inc. Selectively strengthened crankshaft
WO2017119224A1 (ja) * 2016-01-08 2017-07-13 株式会社神戸製鋼所 大型クランク軸
CN108291269A (zh) * 2016-01-08 2018-07-17 株式会社神户制钢所 大型曲轴
US11491541B2 (en) 2019-05-31 2022-11-08 Apollo Machine & Welding Ltd. Hybrid process for enhanced surface hardening

Also Published As

Publication number Publication date
GB1107170A (en) 1968-03-20
DE1284981B (de) 1968-12-12

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