US3739131A - Apparatus for inductively surface hardening workpieces of at least approximately axially symmetrical shape - Google Patents

Apparatus for inductively surface hardening workpieces of at least approximately axially symmetrical shape Download PDF

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Publication number
US3739131A
US3739131A US00272636A US3739131DA US3739131A US 3739131 A US3739131 A US 3739131A US 00272636 A US00272636 A US 00272636A US 3739131D A US3739131D A US 3739131DA US 3739131 A US3739131 A US 3739131A
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United States
Prior art keywords
workpiece
conductor
closed
loop
axially
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Expired - Lifetime
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US00272636A
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English (en)
Inventor
F Reinke
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SMS Elotherm GmbH
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AEG Elotherm GmbH
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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
    • C21D1/06—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
    • 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

  • ABSTRACT An apparatus for inductively surface hardening a workpiece having two heating conductors extending on each side of the workpiece parallel to the workpiece axis and a cross conductor at one end of the workpiece completing the conductor loop.
  • a further conductor is provided about the workpiece with surfaces extending parallel to and slightly separated from inner surfaces of the cross conductor ground part of the circumference and around the workpiece for the rest of the circumference so that current fiow is induced in the further conductor.
  • the further conductor is preferably mounted for axial movement so that the distance between a stop holding one end of the workpiece and the further conductor remains the same.
  • the invention relates to apparatus for inductively surface-hardening at least approximately axially symmetrical workpieces by the rotary method, particularly by using an inductor consisting of two heating conductors extending on each side of the workpiece in the general direction of the workpiece axis and connected near one of the workpiece ends by a connecting conductor which extends crosswise of the workpiece axis and completes the heating conductor loop, this cross conductor having a surface area with faces extending at least nearly parallel to the workpiece axis.
  • Hardening machines equipped with inductors of the above described type have been described for instance in the published specification of German Patent application No. 1,583,331. With particular advantage they can be used for instance for surface-hardening the rear axle shafts of motor vehicles, which require a hardened zone having as uniform a thickness as possible.
  • Such rear axle shafts are usually provided at one end with a flange and at the other end with external splines.
  • the hardened layer on the shaft surface which extends at one end across the fillet up part of the flange, is desired 1 at the other end to involve as much as possible of the splines but, as has been found by experience, it should not extend to the free end face of the shaft because if this were so, cracks would appear between the hardened surface layer and the core material.
  • the connecting cross conductor between the two heating conductors which extend on each side of the workpiece in predetermined axial direction consists of a semicircular conducting bridge, which arches above the workpiece surface and forms part of the heating conductor of the inductor.
  • the hardened layer at this end should not extend beyond a given point towards the free end of the shaft it is the usual practice to allow for variations in the depth of the hardened layer by so designing the inductor in length that, for a given average depth of the hardened zone, this zone will end a given safety distance short of the desirable optimum point.
  • the object of the present invention to contrive apparatus for inductively surface-hardening workpieces that are at least approximately axially symmetrical, by the rotary method, using an inductor consisting of two heating conductors extending on each sideof the workpiece in the general direction of the workpiece axis and being connected near one of the workpiece ends by a connecting conductor which extends crosswise of the workpiece axis and completes the heating conductor loop, in such a way that the apparatus permits the position of the end of the hardened zone to be adjusted.
  • an inductor which in addition to its heating conductor loop also includes a conductor which forms a the and which has a surface area comprising faces which are at least nearly parallel to the workpiece axis, and which extend, in a manner leaving a narrow circumferential clearance gap, around part of the circumference of the closed loop conductor, in close proximity with the corresponding axially parallel faces of the cross conductor, and around another part of its circumference, in close proximity with the end of the workpiece surface that is to be hardened, this closed conductor loop being axially adjustable in relation to the heating conductor loop for the purpose of varying the effective length at the end of the workpiece that will be heated.
  • the closed conductor loop may be axially movably mounted and energy storage means may be provided urging the closed conductor loop towards the workpiece end, as well as a mounting element for engaging said workpiece end and in conventional manner serving to impart rotation to the workpiece about its axis, this mounting element being axially adjustable connected to stop meant for displacing the closed conductor loop against the thrust of said energy storage means into a fixed predetermined position in relation to the work piece end.
  • a conventional mounting element which engages end and im parts rotation to along workpiece may be connected to the axially movable closed conductor loop and thereby, during the workpiece mounting process, axially locate the same in a fixed predetermined position in relation to said workpiece end.
  • the dimensions in the direction of the workpiece axis of the mutually facing axially parallel surface areas of the cross conductor and of the closed conductor loop differ in such manner that, notwithstanding variations in the positions occupied by the closed conductor loop during inductive heating, the mutual overlap between the surface areas and hence the degree of inductive coupling between the cross-conductor and the closed conductor loop will remain constant.
  • corresponding portions of the cross conductor and of the closed conductor loop and/or the portion of the closed conductor loop which faces the workpiece surface may be provided with magnetic yoke cores or laminated magnetic yokes.
  • FIG. 1 shows a side view of one embodiment of this invention heating a workpiece
  • FIG. 2 shows a front view of the embodiment of FIG.
  • FIG. 3 shows a sectional view through l-I in FIG. 2.
  • the region 1 at the end of the workpiece that is to be hardened, the spindle end 2 upon which the workpiece is mounted and a portion of the inductor corresponding to the length of this region are shown in two relatively perpendicular sections.
  • End 1 shown in the drawings of the relatively elongated workpiece, which may be the rear axle shaft of a vehicle, is provided with external splines in which the hardened zone is to terminate a given distance from the end of the shaft.
  • the heating conductor loop of the inductor comprises two heating conductors 4 extending in the direction of the workpiece axis 3.
  • a conductor 5 which extends across the workpiece axis, and which in the illustrated example comprises two separate branches 5' and 5" for completing the loop and providing connections 6 and 7 t inductor terminals (not shown in the drawing).
  • Cross conductor has a surface 8 which is parallel to the workpiece axis 3 and so shaped that this surface in conjunction with a portion 9 of the workpiece surface that is to be hardened defines an opening or channel (FIG. 2).
  • This channel contains a conductor 10 which closes upon itself, and which also comprises a surface 11 which is parallel to the workpiece axis, and which conforms with the shape of the axially parallel surface 8 of the cross conductor 5 and of the end portion 9 of the workpiece that is to be hardened, in such manner that a narrow all-around clearance gap remains.
  • the heating conductor loop and the closed conductor loop 10 are preferably made of copper tubes of rectangular cross section and in operation a coolant circulates through their interiors. In FIG. 2 the connections 12 for the coolant of the closed conductor loop 10 are shown.
  • magnetic yoke cores or laminated yokes 13 and 14 are attached to corresponding sections of these conductors as shown in FIG. 3.
  • closed conductor loop 10 For the purpose of concentrating the field in this part 9 of the workpiece, closed conductor loop 10, as is otherwise conventional in inductors, is armed with a laminated magnetic yoke 15 in this region.
  • FIG. 3 is a section of the arrangement taken on the line I-l in FIG. 2.
  • Closed conductor loop 10 is attached to a holder 16 made of electrically insulating material and mounted slidably in the axial direction on two pins 19 secured to an inductor bracket 18.
  • Two compression springs 20 which serve as energy storage means are likewise mounted on the pins 19 and bear at one end against the inductor bracket 18, urging holder 16, together with closed inductor loop 10, in the direction indicated by an arrow 21.
  • Spindle 2 of which the rotating center 22 engages the end 23 of the workpiece carries a stop 24 which is axially shiftable clamped to the spindle.
  • the abutment face of the stop 24 displaces the holder 16 and the closed conductor loop 10 against the resistance of the compression springs 20 in such a way that, irrespectively of differences in the overall length of the workpiece, closed conductor loop 10 will be in a position which is precisely determined in relation to the end 23 of the workpiece, so that the heating zone generating the end of the hardened zone by inductive heating will also terminate at an exactly predetermined distance from the end 23 of the workpiece.
  • the width a of the cross conductor 5 measured in the axial direction of the workpiece, exceeds the width b of the closed conductor loop 10 by at least the length of its axial adjustability range so that, irrespectively of the final position of the closed conductor loop 10, its entire peripheral face will always be overlapped by the corresponding face of the cross conductor 5.
  • a simpler embodiment of the arrangement according to the invention consists in directly attaching the closed conductor loop, by suitable holding means in an axially adjustable manner, directly to the mounting element of the work, such as a spindle, so that it will necessarily have been moved into the correct prescribed position in relation to the end of the workpiece when the mounting element grips the workpiece end.
  • This variant may be used with advantage when the mounting, inductive heating, quenching and final release of the workpiece all take place at one and the same station in the hardening machine.
  • the closed conductor loop provided with a suitable holder is axially adjustably attached to the support means carrying the inductor.
  • This modification will be particularly useful when the nature of the mounting device ensures that the contemplated end of the mounted workpiece will always occupy exactly the same position in relation to the inductor.
  • an apparatus for inductively surface-hardening at least approximately axially symmetrical workpieces by the rotary method having an inductor with two heating conductors extending on each side of the workpiece in the general direction of the workpiece axis and connected near one of the workpiece ends by a connecting conductor which extends cross wise of the workpiece axis and completes the heating conductor loop, said cross conductor having a surface with faces extending at least nearly parallel to the workpiece axis, the improvement including a further conductor forming a closed loop, and having a surface with faces which are at least nearly parallel to the workpiece axis and which extend in a manner leaving a narrow circumferential clearance gap, around part of the circumference of the closed loop conductor, in close proximity with the corresponding axially parallel faces of the cross conductor and, around another part of its circumference, in close proximity with the end of the workpiece surface that is to be hardened, and means for axially adjusting said closed conductor loop in relation to said heating conductor loop to vary
  • said closed conductor loop is axially movably mounted and energy stored means are provided urging the closed conductor loop towards the workpiece end as well as a mounting element for engaging said workpiece end and in conventional manner serving to impart rotation to the workpiece about its axis, said mounting element being axially adjustably connected to stop means adapted to displace the closed conductor loop against the thrust of the said energy storage means into a fixed predetermined position in relation to said workpiece end.
  • a mounting element of basically conventional kind is disposed for engaging said workpiece end and for imparting rotation thereto, said mounting element being connected to the axially adjustably movable closed conductor loop and thereby during the workpiece mounting process axially locating the same in a fixed predetermined position in relation to said workpiece end.
  • the further improvement wherein the dimensions in the direction of the workpiece axis of the mutually facing axially parallel surface areas of the cross conductor and of the closed conductor loop differ in such manner that, notwithstanding variations in the positions occupied by the closed conductor loop during inductive heating the mutual overlap between the said surface areas and hence the degree of inductive coupling between the cross conductor and the closed conductor loop remains constant.
  • An apparatus for inductively surface hardening a workpiece comprising:
  • An apparatus as in claim 8 further including stop means for holding an end of said workpiece including means for engaging said mounting means for urging said mounting means along said workpiece axis.
  • said mounting means includes a shaft, means for holding said further conductor and slidable along said shaft including a portion for receiving said engaging means so that said engaging means urges said holding means a ong said shaft, a member connecting said cross conductor to said shaft, and a spring mounted on said shaft urging said holding means toward said engaging means.

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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)
  • General Induction Heating (AREA)
US00272636A 1971-09-23 1972-07-17 Apparatus for inductively surface hardening workpieces of at least approximately axially symmetrical shape Expired - Lifetime US3739131A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2147518A DE2147518C3 (de) 1971-09-23 1971-09-23 Vorrichtung zum induktiven Oberflächenhärten von zumindest angenähert rotationssymmetrischen Werkstücken im Umlaufverfahren

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US3739131A true US3739131A (en) 1973-06-12

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US00272636A Expired - Lifetime US3739131A (en) 1971-09-23 1972-07-17 Apparatus for inductively surface hardening workpieces of at least approximately axially symmetrical shape

Country Status (6)

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US (1) US3739131A (ja)
JP (1) JPS535604B2 (ja)
DE (1) DE2147518C3 (ja)
FR (1) FR2153364B1 (ja)
GB (1) GB1384929A (ja)
IT (1) IT965449B (ja)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5138123A (en) * 1989-11-02 1992-08-11 Blum Gmbh Inductively operated heating apparatus for plastic materials

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS51145063U (ja) * 1975-05-16 1976-11-22
JPS5918143Y2 (ja) * 1978-02-15 1984-05-25 株式会社デンソー 内燃機関用エアクリ−ナエレメント
JPS5933890Y2 (ja) * 1978-03-07 1984-09-20 株式会社デンソー 内燃機関用エアクリ−ナエレメント
JPS5830525A (ja) * 1981-08-18 1983-02-23 Nippon Seiko Kk 動圧流体軸受装置
JPS59175717U (ja) * 1983-05-11 1984-11-24 大豊工業株式会社 高温回転軸用軸受装置
JPH0729302Y2 (ja) * 1986-12-25 1995-07-05 三菱電機株式会社 磁性粒子式トルクリミッタ

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5138123A (en) * 1989-11-02 1992-08-11 Blum Gmbh Inductively operated heating apparatus for plastic materials

Also Published As

Publication number Publication date
JPS535604B2 (ja) 1978-03-01
FR2153364A1 (ja) 1973-05-04
GB1384929A (en) 1975-02-26
DE2147518C3 (de) 1974-02-07
FR2153364B1 (ja) 1976-08-13
DE2147518A1 (de) 1973-04-05
JPS4840615A (ja) 1973-06-14
IT965449B (it) 1974-01-31
DE2147518B2 (de) 1973-07-19

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