US20130098512A1 - Mechanical component and method of surface hardening - Google Patents

Mechanical component and method of surface hardening Download PDF

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Publication number
US20130098512A1
US20130098512A1 US13/808,046 US201113808046A US2013098512A1 US 20130098512 A1 US20130098512 A1 US 20130098512A1 US 201113808046 A US201113808046 A US 201113808046A US 2013098512 A1 US2013098512 A1 US 2013098512A1
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United States
Prior art keywords
hole
mechanical component
interior surface
induction coil
electromagnetic induction
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Abandoned
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US13/808,046
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English (en)
Inventor
Marco Burtchen
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Individual
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Individual
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Publication of US20130098512A1 publication Critical patent/US20130098512A1/en
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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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/34—Methods of heating
    • C21D1/42—Induction heating
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/06—Surface hardening
    • C21D1/09—Surface hardening by direct application of electrical or wave energy; by particle radiation
    • C21D1/10—Surface hardening by direct application of electrical or wave energy; by particle radiation by electric induction
    • 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
    • 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
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • the present invention concerns a mechanical component having a hole extending therethrough, such as a pierced roller.
  • the present invention also concerns a method for surface hardening at least one part of an interior surface of such a mechanical component
  • Induction hardening is a heat treatment in which a metal component is heated to the ferrite/austenite transformation temperature or higher by induction heating and then quenched. The quenched metal undergoes a martensitic transformation, increasing the hardness and brittleness of the surface of a metal component. Induction hardening may be used to selectively harden areas of a mechanical component without affecting the properties of the component as a whole.
  • the induction head and the pipe are moved relative to one another in an axial direction during the hardening process, the effective hardening depth of the induction hardening process being controlled in accordance with the momentary position of the induction head in the pipe.
  • the effective hardening depth is greater in the final areas than in the central area, thus providing the pipe with great resistance to wear.
  • U.S. Pat. No. 4,949,758 discloses a process for hardening the interior surface of a long (8-32 feet i.e. 244-975 cm), thin-walled (wall thickness 1 ⁇ 8 to 1 ⁇ 4 inch, i.e. 3-6 mm), small inside diameter (11 ⁇ 4 to 31 ⁇ 4 inch, i.e. 32 to 83 mm) tubular member. More particularly, it relates to a process involving progressive heating with an internally positioned, electro-magnetic induction coil, followed by immediate quenching with a quench ring assembly, to develop a martensitic case on the inner surface of the tube.
  • carburizing is usually used since the gaseous, liquid, solid or plasma source of carbon that is used in carburizing, can penetrate into holes and tight gaps.
  • Carburizing is a heat treatment process in which iron or steel is heated in the presence of another material that liberates carbon as it decomposes.
  • the outer surface or case will have higher carbon content than the original material.
  • the higher carbon content on the outer surface becomes hard, while the core remains soft (i.e. ductile) and tough.
  • An object of the invention is to provide an improved non-through hardened mechanical component having a hole of uniform or non-uniform cross section extending therethrough, i.e. extending at least part of the way through the mechanical component, whereby the maximum transverse dimension of the hole is 31.75 mm or less and whereby the minimum thickness of the mechanical component is 7 mm, measured from an interior surface constituting the outer perimeter of the hole radially outwards to an outer surface of the mechanical component.
  • a mechanical component in which at least one part of interior surface material of the mechanical component constituting the outer perimeter of the hole comprises a martensitic microstructure produced by induction hardening using an electromagnetic induction coil positioned inside the hole followed by immediate quenching using a quenching device that is positioned inside the hole when the electromagnetic induction coil has been removed from the hole or while the electromagnetic induction coil is being removed from said hole.
  • the at least one part of the interior surface material may have a hardness within the range of 55-75 HRC on the Rockwell scale at the interior surface, preferably 58-63 HRC and the material of increased hardness may extend to a depth of about 0.5-6 mm below the interior surface, preferably 1-4 mm below the interior surface.
  • At least one part of the interior surface of such a non-through hardened mechanical component will exhibit increased surface hardness, increased wear resistance and/or increased fatigue and tensile strength.
  • the induction hardening heat treatment used to produce such a mechanical component is more energy efficient and cost effective than a carburizing heat treatment and it has a shorter cycling time and provides better distortion control than a carburizing heat treatment.
  • properties, such as the hardness, microstructure and residual stress, of the at least one part of the interior surface may be tailored as desired for a particular application.
  • the at least one part of the interior surface extends to a depth of 0.2, 0.3, 0.4, 0.5, 0.75 or 1.0, below said interior surface.
  • the at least one part of the interior surface extends to a depth of 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5 or 6.0 mm below said interior surface.
  • the maximum transverse dimension of the hole is 5-31.75 mm, preferably 10-30 mm.
  • the minimum thickness of the mechanical component measured from the interior surface radially outwards towards the outer surface of the mechanical component is 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm or more.
  • At least one part of the interior surface constituting the outer perimeter of the hole comprises a thread.
  • the mechanical component constitutes a rotationally symmetrical mechanical component.
  • the mechanical component constitutes a rolling element or roller, or a component for an application in which is subjected to alternating Hertzian stresses, such as rolling contact or combined rolling and sliding, such as a slewing bearing or a raceway for a bearing.
  • the mechanical component may for example be used in automotive and machine applications which require high wear resistance and/or increased fatigue and tensile strength.
  • the mechanical component comprises, or consists of a carbon or alloy steel with an equivalent carbon content of 0.40 to 1.10%, preferably a high carbon chromium steel.
  • the mechanical component comprises/consists of 50CrMo4 steel having a composition in weight % 0.50 C, 0.25 Si, 0.70 Mn, 1.10 Cr, 0.20 P, a 100Cr6 steel or SAE 1070.
  • the present invention also concerns a method for surface hardening at least one part of an interior surface of a mechanical component having a hole maximum transverse dimension of 31.75 mm or less extending therethrough, whereby the mechanical component has a minimum thickness of 7 mm, measured from an interior surface constituting the outer perimeter of the hole radially outwards to an outer surface of the mechanical component.
  • the method comprises the steps of inserting an electromagnetic induction coil within the hole, heating the at least one part of the interior surface to the ferrite/austenite transformation temperature or higher by induction heating, removing the electromagnetic induction coil from the hole and simultaneously or subsequently inserting a quenching device within the hole to immediately quench said at least one part of the interior surface.
  • the method comprises the step of inserting the electromagnetic induction coil into one end of the hole, removing the electromagnetic induction coil from the hole via the same end of the hole and inserting the quenching device from the other end of the hole.
  • the method according to the present invention is based on the finding that such a method ensures that the interior surface of such a mechanical component is heated and quenched sufficiently quickly to obtain the desired microstructure in the interior surface.
  • the method comprises the step of also providing at least one external quenching device on the outside of the mechanical component to immediately quench the at least one part of the interior surface.
  • at least one external quenching device on the outside of the mechanical component to immediately quench the at least one part of the interior surface.
  • an induction coil as used throughout this document with reference to the mechanical component and method according to the present invention is intended to mean one or more induction coils.
  • a plurality of induction coils operating in the same or a different manner, for example at the same or different frequencies, may for example be used to simultaneously or consecutively heat a plurality of parts of the interior surface (and/or the outer surface) of a mechanical component, or one or more parts of a plurality of mechanical components.
  • the method comprises the step of heating the at least one part of the interior surface to a depth of 0.2, 0.3, 0.4, 0.5, 0.75 or 1.0 mm below said interior surface.
  • the at least one part of the interior surface extends to a depth of 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5 or 6.0 mm below said interior surface.
  • the maximum transverse dimension of the hole is 5-31.75 mm, preferably 10-30 mm.
  • the minimum thickness of the mechanical component measured from the interior surface radially outwards towards the outer surface of the mechanical component is 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm or more.
  • At least one part of the interior surface constituting the outer perimeter of the hole comprises a thread.
  • the mechanical component constitutes a rotationally symmetrical mechanical component.
  • the mechanical component constitutes a roller or a component for an application in which is subjected to alternating Hertzian stresses, such as rolling contact or combined rolling and sliding.
  • FIGS. 1 & 2 show the steps of a method according to an embodiment of the present invention.
  • FIG. 3 shows a cross section of a mechanical component according to an embodiment of the invention.
  • FIG. 1 schematically shows a thick-walled rotationally symmetrical mechanical component 10 manufactured from bearing steel, namely a cylindrical roller, in cross section.
  • the roller 10 is, for example, made of 50CrMo4 steel and comprises a hole 12 having a diameter d and a uniform circular cross section which extends all the way through the centre of the component in the longitudinal direction thereof.
  • the roller 10 has a minimum thickness T measured from an interior surface 12 a constituting the outer perimeter of the hole 12 radially outwards to an outer surface 10 a of the roller 10 (or from 12 b to 10 b ).
  • the minimum thickness T is 7 mm, 10 mm, 20 mm, 30 mm or more.
  • the diameter d of said hole 12 is 31.75 mm or less.
  • the hole 12 may alternatively be conical for example and thus have a non-uniform cross sectional size, whereupon its maximum diameter is 31.75 mm or less. Alternatively or additionally, the hole 12 may be arranged to have a non-uniform cross sectional shape.
  • an electromagnetic induction coil 14 is inserted inside the hole 12 at the left hand side end of the hole.
  • a source of high frequency electricity (about 1 kHz to 400 kHz) is used to drive a large alternating current through the induction coil 14 .
  • the relationship between operating frequency and current penetration depth and therefore hardness depth is inversely proportional, i.e. the lower the frequency the greater the hardness depth.
  • the passage of current through the induction coil 14 generates a very intense and rapidly changing magnetic field, and the part of the interior surface 12 a , 12 b to be heated is placed within this intense alternating magnetic field. Eddy currents are generated within that part of the interior surface 12 a , 12 b and resistance leads to Joule heating of the metal in that part of the interior surface 12 a , 12 b .
  • the interior surface 12 a , 12 b of the roller 10 is heated to the ferrite/austenite transformation temperature or higher by induction heating and preferably maintained at that temperature for 10-40 seconds.
  • the induction coil 14 is then removed via left-hand side end of the hole 12 and a quenching device 16 , such as a quench spray or ring, is inserted via the right-hand side hole 12 to immediately quench the at least one part of the interior surface 12 a , 12 b that has been heat treated.
  • the at least one part of the interior surface 12 a , 12 b may for example be quenched to room temperature (20-25° C.) or to 0° C. or less.
  • the quenching device 16 is arranged to provide a water-, oil- or polymer-based quench to the heated interior surface layer 12 a , 12 b whereupon a martensitic structure which is harder than the base metal of the roller 10 is formed.
  • the microstructure of the remainder of the roller 10 remains essentially unaffected by the heat treatment and its physical properties will be those of the bar from which it was machined. It should be noted that the 5 quenching device 14 may be inserted via the same (left-hand side) end of the hole 12 as the induction coil 14 after the induction coil 14 has been removed from the hole 12 .
  • a 60-200 kW power supply a frequency of 20-60 kHz, preferably 10-30 kHz or 15-20 kHz a total heating time of 10-40 seconds and a quenching rate and time of 10 2001/min and quenching time of 40-70s respectively may be used to obtain a mechanical component according to the present invention.
  • FIG. 2 shows the position of the quenching device 16 while quenching is taking place.
  • FIG. 2 also shows that one or more additional external quenching devices 20 may also 15 be positioned on the outside of the roller during the quenching step.
  • At least one part of the outside surface 10 a , 10 b , 10 s of the roller 10 may be subjected to a surface hardening heat treatment, such as induction hardening, flame hardening or any other conventional heat treatment.
  • roller 10 in the illustrated embodiment has been shown in a horizontal position with the induction coil 14 and quenching device 16 being inserted horizontally, it should be noted that the roller 10 may be oriented in any position.
  • An induction coil 14 and quenching device 16 may for example be inserted vertically into a 25 roller 10 from the same or different ends of the hole 12 .
  • An induction coil 14 may for example be inserted into a roller 10 by lowering it vertically into the roller's hole 12 and a quenching device may be inserted into a roller's hole 12 by raising it vertically as the induction coil 14 is withdrawn by raising it vertically.
  • FIG. 3 shows a cross section of the roller 10 after the heat treatment.
  • Part 22 of interior surface material 12 a , 12 b of the roller 10 constituting the outer perimeter of the hole 12 extending therethrough comprises a martensitic microstructure produced by induction hardening using the electromagnetic induction coil 14 positioned inside the hole 12 followed by immediate quenching using a quenching device 16 positioned inside the hole 12 and optionally one or more external quenching devices 20 .
  • the method according to the present invention results in the formation of a transition zone visible in both hardness and in microstructure.
  • the heat treated part 22 of the interior surface material 12 a , 12 b may namely have a hardness within the range of 55-75 HRC on the Rockwell scale at the interior surface 12 a , 12 b , preferably 58-63 HRC.
  • the volume of material of increased hardness 22 may for example extend to a depth of 1 to 2 mm below the interior surface 12 a , 12 b measured radially outwards from the interior surface 12 a , 12 b of the roller 10 to the outer surface of the roller 10 a , 10 b respectively.
  • Such a roller 10 may be used for any application in which a part of the interior surface 12 a , 12 b is subjected to increased wear, fatigue or tensile stress. Alternatively, the entire interior surface 12 a , 12 b may be subjected to the method according to the present invention, depending on the application for which the roller 10 is to be used.
  • the interior surface 12 a , 12 b of the roller 10 may for example comprise a thread (not shown) arranged to mate with a corresponding thread of another component.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
  • Rolling Contact Bearings (AREA)
US13/808,046 2010-07-02 2011-05-27 Mechanical component and method of surface hardening Abandoned US20130098512A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE10007201 2010-07-02
SE1000720 2010-07-02
PCT/SE2011/000093 WO2012002862A1 (en) 2010-07-02 2011-05-27 Mechanical component and method of surface hardening

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US (1) US20130098512A1 (zh)
EP (1) EP2596138A1 (zh)
JP (1) JP2013535570A (zh)
CN (1) CN103069018A (zh)
WO (1) WO2012002862A1 (zh)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10814437B2 (en) 2014-11-18 2020-10-27 Komatsu Ltd. Machine component and method for producing the same

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CN110848261B (zh) * 2018-07-27 2021-06-04 舍弗勒技术股份两合公司 用于滚动轴承的滚动体和滚动轴承
CN114921635B (zh) * 2022-05-11 2023-10-13 一汽解放汽车有限公司 一种前轴的热处理方法
CN116790972B (zh) * 2023-02-22 2023-11-24 徐州徐工基础工程机械有限公司 一种50CrMo4液压凿岩机冲击活塞性能控制方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009167484A (ja) * 2008-01-17 2009-07-30 Thk Co Ltd 筒形金属部材用熱処理装置

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5977979A (ja) * 1982-10-15 1984-05-04 Topy Ind Ltd 履帯用ブツシングおよびその生産方法
JPH0235011B2 (ja) * 1983-05-13 1990-08-08 Daiichi Koshuha Kogyo Kk Kokannonaimenkanetsuhohooyobisorenimochiiruseigohenatsuki
US4949758A (en) * 1985-07-17 1990-08-21 Quinn's Oilfield Supply Ltd. Thin-walled small-bore steel tube with case hardened internal surface
US5702667A (en) * 1996-08-16 1997-12-30 Caterpillar Inc. Method and apparatus for heat treating a bushing
JP4187334B2 (ja) * 1998-01-29 2008-11-26 トピー工業株式会社 中空円筒状ワークの熱処理方法
JP3618624B2 (ja) * 1999-10-29 2005-02-09 富士電子工業株式会社 ボールナットの高周波焼入方法
DE10112295B4 (de) * 2001-03-08 2004-07-29 Berstorff Gmbh Herstellung eines Zylindergehäuses eines Doppelschneckenextruders
CN1203256C (zh) * 2002-12-19 2005-05-25 牛君 不锈钢抽油汞的制备方法
JP4188128B2 (ja) * 2003-04-15 2008-11-26 高周波熱錬株式会社 筒状部材内周面焼入方法
DE102006041696A1 (de) * 2006-09-06 2008-03-27 Schneiders, Servatius Verfahren zur Herstellung eines Betonförderrohrs
JP5117057B2 (ja) * 2007-01-26 2013-01-09 高周波熱錬株式会社 焼入装置及び焼入方法
JP2009019237A (ja) * 2007-07-12 2009-01-29 Komatsu Ltd 高周波焼入装置及び部材の製造方法

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009167484A (ja) * 2008-01-17 2009-07-30 Thk Co Ltd 筒形金属部材用熱処理装置

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Nee, John G. (2010). Fundamentals of Tool Design (6th Edition) - 2.6.1.2 Stress Relieving. Society of Manufacturing Engineers (SME). *
Timken. Timken Ball Bearings Catalog. N.p.: Timken, 2014. Print. *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10814437B2 (en) 2014-11-18 2020-10-27 Komatsu Ltd. Machine component and method for producing the same

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WO2012002862A1 (en) 2012-01-05
EP2596138A1 (en) 2013-05-29
JP2013535570A (ja) 2013-09-12
CN103069018A (zh) 2013-04-24

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