WO2010007635A1 - Method and device for localized induction hardening treatment of mechanical components, specifically thrust blocks for large-sized rolling bearings - Google Patents

Method and device for localized induction hardening treatment of mechanical components, specifically thrust blocks for large-sized rolling bearings Download PDF

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Publication number
WO2010007635A1
WO2010007635A1 PCT/IT2008/000475 IT2008000475W WO2010007635A1 WO 2010007635 A1 WO2010007635 A1 WO 2010007635A1 IT 2008000475 W IT2008000475 W IT 2008000475W WO 2010007635 A1 WO2010007635 A1 WO 2010007635A1
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WO
WIPO (PCT)
Prior art keywords
inductor
inductors
hardened
annular element
thrust block
Prior art date
Application number
PCT/IT2008/000475
Other languages
French (fr)
Inventor
Mariolino Cesano
Fabrizio Dughiero
Original Assignee
Saet S.P.A.
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 Saet S.P.A. filed Critical Saet S.P.A.
Priority to EP08808194A priority Critical patent/EP2331716A1/en
Priority to PCT/IT2008/000475 priority patent/WO2010007635A1/en
Publication of WO2010007635A1 publication Critical patent/WO2010007635A1/en

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Classifications

    • 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
    • C21D9/40—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rings; for bearing races
    • 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
    • C21D2221/00—Treating localised areas of an article
    • 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 relates to a method and device for performing a localized induction hardening treatment on mechanical components, specifically for hardening large-sized rolling bearing thrust block tracks.
  • the induction hardening treatment of large- sized thrust blocks bearings tracks displays several problems, the most important of which are the relatively slow speed of the hardening process, which does not exceed 300-350 mm/min, inaccuracies and difficulties to obtain a desired hardening profile, which ideally requires different hardening intensities at different zones of the tracks, the need to have inductors which perfectly 'mimic' the transversal profile of the track and which therefore cannot be used for even only slightly different thrust blocks, and the formation of a partial tempering zone, known as 'soft zone' .
  • the induction hardening process is typically performed as diagrammatically shown in figure 2, wherein one or preferably a pair of inductors A, B heat the thrust block, which is rotated with respect to the inductors in a prefixed direction of rotation; downstream of the inductors, where the term 'downstream' refers to the sense of rotation of the thrust block, a cooling shower C, which performs the hardening (quenching) itself, is arranged.
  • the method according to the invention consists in performing a localized induction hardening treatment of large- sized bearing thrust blocks using at least . a first and a second inductors at least initially arranged reciprocally in tandem with respect to the track to be hardened, which are held at a prefixed distance from the surface of the track and parallelly to the surface itself; and including, in combination, the steps of : - rotating the thrust block at a first angular speed with respect to the first inductor, which is instead held angularly fixed; simultaneously, rotating the second inductor about the thrust block and in the same sense of rotation as the thrust block but at a second angular speed, faster than the first, so as to leave a first side of the first inductor and, once a complete rotation has been performed with respect thereto, arranging itself side-by-side to a second side of the first inductor, on the side opposite to the first side; simultaneously with the preceding steps, electrically feeding said inductors so as to produce a localized heating of the thrust block
  • the device for implementing the method of the invention includes, according to a further aspect of the invention, at least a first and a second inductors arranged at least in a first operating position reciprocally in tandem with respect to a surface of an annular element to be hardened, positioning means for keeping the inductors parallel to and at a prefixed distance from the surface of the annular element to be hardened, and quenching means of the annular element operatively associated to the inductors for producing a localized hardening of the aforesaid surface of the annular element to be hardened; and furthermore it includes: first handling means to rotate the annular element to be hardened at a first angular speed about the symmetry axis thereof in front of the first inductor, which is carried by positioning means in a fixed angular position with respect to the annular element to be hardened; and second handling means to rotate the second inductor, at a second angular speed faster than the first and concentrically to the annular element to be hardened, in the same sense of
  • the method and device according to the invention allow to easily implement further measures to increase the hardening uniformity and in actual fact to eliminate the soft zone, preventing the occurrence of localized tempering.
  • a third inductor may be provided arranged angularly fixed in a position immediately adjacent to the second side of the first inductor and in use facing and parallel to the surface of the annular element to be hardened; and means for actuating the third inductor only when the second inductor is at a prefixed, relatively short distance from the second side of the first inductor.
  • handling means, of the first and second_ inductors may be provided adapted in use to direct the electric current through the inductors so that, at least when the second inductor is in a position immediately adjacent to the second side of the first inductor, the magnetic fluxes of the first and second inductors are at least partially concatenated through a portion of the annular element to be hardened locally facing the inductors themselves.
  • the first and the second inductors may be asymmetrically configured in the relative direction of rotation of the annular element to be hardened, so as to obtain an effect similar to the preceding one and, in essence, to apply a more effective magnetic field to the element to be hardened in order to obtain the required heating profile; specifically, the inductors are provided with profiled concentrators, on a plane perpendicular to the surface to be hardened, with an asymmetric shape on such a plane, such as an F- shape, a C-shape, a T-shape, an E-shape, an L-shape, having for example asymmetric arms of such a shape facing in use the element to be hardened and wherein a first 'open' side of the concentrator of the first inductor corresponds to the second side of the first inductor; and wherein when the second inductor is in a position adjacent to the second side of the first inductor, the shapes defined by the concentrators of the
  • figure 1 diagrammatically depicts an annular element to be hardened, shown in radial section and a detail of the hardening device according to the invention
  • figure 2 diagrammatically " shows an induction hardening method according to the known art
  • figures from 3 to 6 diagrammatically show corresponding top plan ⁇ iews of the induction hardening device according to the invention shown in different configurations each time, corresponding to different steps of the hardening method according to the invention
  • figures 7 and 8 diagrammatically show plan views of a hardening device acco ' rding to the invention during some additional, optional steps of the method according to the invention
  • figures 9 and 10 diagrammatically show in elevation and radial section views, similar details of the hardening device in figures 3-6 during the implementation of the method according to the invention.
  • numeral 1 indicates as a whole a device for performing a localized induction hardening treatment on a surface 2 of an annular element 3; specifically, the element 3 consists in large-sized bearing thrust blocks and the surface 2 -belongs to a rolling track 4 of a thrust block 3.
  • the device 1 is constructed so as to ensure that a minimum prefixed hardening depth T is obtained on the track 4 along the entire angular extension of the element 3 and includes at least a first inductor 6 and a second inductor 8 at least initially arranged in a first operating position thereof, shown in top plan view in figure 3, reciprocally in tandem with respect to the surface 2 of the annular element 3 to be hardened, i.e. as in the state of the art shown in figure 2, where A and B indicate two inductors arranged in tandem, C indicates a cooling shower arranged in turn in tandem with respect to the inductor B, and D indicates the element to be hardened.
  • the device 1 further includes positioning means 10,12 (known, figure 3, and only indicated by a dashed line and as blocks for simplicity) for keeping in use the inductors 6,8 parallel to and at a prefixed distance from the surface 2 of the annular- element 3 to be hardened-, and quenching means 13 of the annular element 3, e.g. of the type of the shower C of the state of the art, operatively associated in the manner shown below to the inductors 6,8 to produce a localized hardening of the surface 2 of the annular element 3 to be hardened; e.g. each inductor 6,8 may be integrally provided with a shower 13b,13 ⁇ a respectively, or one or two showers 13 may be carried by the positioning means 10,12, even independently from the inductors 6,8.
  • positioning means 10,12 known, figure 3, and only indicated by a dashed line and as blocks for simplicity
  • the positioning means 10,12 preferably consist, in . turn, of automated arms or towers, with three, four or more numerically controlled axes, well known to those skilled in the art and which therefore are not described in detail.
  • the device 1 further includes in combination: first handling means 20 to rotate, at a first angular speed Vl
  • the angular speed V2 is different from Vl and specifically is higher in module and identical in direction and sense to Vl, so that, in
  • the second inductor 8 is forced to leave its position in tandem with the first inductor 6, moving away from it towards the part of one side 22 of the inductor 6 itself
  • the first and second handling means 20 and 21 are reciprocally and operatively connected by means of a device 26 (figure 1) adapted to ensure an either constant or even variable ratio (e.g. according to the 0 relative angular position of the inductors 6,8) , or however desired, between the angular speeds Vl and V2 ; preferably, such a ratio is constant and such that
  • V2 2 -Vl 5 i.e. it is such that the angular rotation speed V2 of the inductor 8 is double the rotation speed of the element (thrust block) 3 to be hardened.
  • the handling means 20 consist of a rotating table 30 (figures 1 and 3) actuated by motor means 31, while the handling means 21 include an arm 33 arranged radially oriented with respect to the annular element (thrust block) 3 to be hardened, and motor means 34 for the arm 33 radially arranged in use within the annular element 3 to be hardened, e.g. either over or inside the rotating table 30 (in the latter case, if the table 30 is also annular) ; the motor means 31 and 34 may either be reciprocally independent, in which case the device 26 consists of an electronic control unit, or may be operated by a common motor, in which case the device 26 is a mechanical transmission device of the motion between the motor means 31 and the motor means 34.
  • Figures 7 and 8 show an embodiment Ib of the device 1 just described, which in addition to the inductors 6,8 includes a third inductor 40 angularly arranged fixed in a position immediately adjacent to the second side 23 of the first inductor 6 and in use facing and parallel to the surface 2 of the annular element 3 to be hardened, thus in tandem with the inductor 6 with respect to the thrust block 3 and upstream of the latter with respect to the sense of rotation of the thrust block 3.
  • the device Ib further includes means 42, of known type (and thus diagrammatically indicated by a block) , for actuating the third inductor 40, i.e. for feeding an electric current therein at a predetermined voltage so as to make the inductor 40 generate an electromagnetic field which concatenates with the thrust block 3 on the surface 2 thus causing a localized heating by electromagnetic induction of the track 4.
  • the means 42 are adapted (e.g. because they are provided with an electronic control unit connected to specific sensors - not shown - of the angular position of the rotating inductor 8, i.e. of the arm 33) to actuate the inductor 40 in the aforesaid manner only when the second inductor 8 is at a prefixed, relatively short distance K from the second side 23 of the first inductor 6.
  • 'Relatively short' hereinafter means a distance equal to only a fraction of a fourth of the circumference of the element 3.
  • the device 1, thus based on only two inductors 6 and 8, may be provided (figure 10) with actuating means 50 of the inductors 6,8 (where the term 'actuating' means what previously described with regards to the actuating means 42 of the inductor 40) , adapted to direct, in use, the electric current through such inductors 6,8 so that at least partially when the second inductor 8 is in a position immediately adjacent to the second side 23 of the first inductor 6, the magnetic fluxes of the first and second inductors 6,8 are at least partially concatenated through a portion of the annular element 3 in that moment facing the inductors 6,8, as shown by means of the flux lines F illustrated with a dashed line in figure 10.
  • the actuating means 50 of the inductors 6,8 are adapted to circulate, always or only after a given moment, the electric current.
  • I in the inductors 6,8 in an opposite sense, as diagrammatically shown in figure 10, where the current I entering the plane of the sheet is depicted by a St.
  • Andrew's cross while the current I exiting from the plane of the sheet is depicted by a dot, so that the current I on the side 23 of the inductor 6 circulates in the same sense as the current I which circulates on the side of the inductor 8 immediately adjacent to the side 23 corresponding to the stroke end of the inductor 8 which, as previously mentioned, corresponds to that which follows an essentially complete rotation of -the " inductor 8 about the axis X, thus to a complete rotation decreased by the dimensions of the inductor 6 measured in the direction of rotation of the inductor 8.
  • the inductors 6 and 8 of the device 1 may be configured asymmetrically in the relative direction of rotation with respect to the annular element 3 to be hardened, so that, when the second inductor 8 is in a position immediately adjacent to the second side 23 of the first inductor 6, the magnetic fluxes of the first and the second inductor 6,8 are at least partially concatenated through the annular element 3 to be hardened as diagrammaticalIy shown by the dashed flux line F in figure 9.
  • the inductors 6,8 are provided with shaped concentrators 61,81, on a plane perpendicular to the surface 2 to be hardened, i.e. in radial section (with reference to axis X) , with an asymmetric shape on such a plane, such as an F- shape, a C-shape, a T- shape, an E-shape, an L- shape (in the illustrated non- limitative example, the shape is as an F) , having, for example, the asymmetric arms of such a shape facing in use towards the element 3 to be hardened and wherein a first 'open' side of the concentrator of the first inductor displays the arms thereof, in the illustrated case defined by transverse portions 62,63 and 82,83 of the F-shaped concentrators 61,81, facing in use towards the track 4 and oriented so that, on one side, the open side of the F formed by the concentrator 61 corresponds to the second side 23 of the in
  • the shapes, in this case the F-shapes, defined by the concentrators 61 and 81 are specularly and symmetrically arranged towards the annular element 3 to be hardened, with the open side portions reciprocally adjacent and the portions 62,82 arranged on opposite sides.
  • a method for performing a localized induction hardening treatment of rolling- tracks 4 of large- sized bearing thrust blocks 3 - may be implemented, according to the invention, ensuring a prefixed minimum hardening depth
  • the inductors 6 and 8 are arranged reciprocally in tandem along the track 4 to be hardened, with the inductor 8 arranged adjacent to the side 22 of the inductor 6; subsequently, again by keeping the inductors 6,8, at a prefixed distance from the surface 2 of the track 4 and" parallel to the surface 2 itself by means of the positioning means 10,12, the thrust block 3 is rotated about the axis X, by means of the table 30, at a first angular speed Vl, while the inductor 6 is held angularly fixed.
  • the second inductor 8 is also rotated about the axis X by means of the arm 33, thus concentrically about the thrust block 3, in the same sense of rotation as the thrust block 3 but at a second angular speed V2 faster than Vl, preferably chosen equal to double Vl, so as to leave the first side 22 of the inductor ' 6 and, once a complete rotation has been essentially performed with respect thereto (i.e. a complete rotation decreased by the dimensions of theinductor 6 in the direction of rotation of the inductor 8) , arrange side-by- side in tandem to the second side 23 of the inductor 6, on the side opposite to the first side 22.
  • a step of electrically feeding the inductors 6,8, is performed e.g. by means of the actuating means 50, so as to produce a localized heating of the track 4 of the thrust block 3 by electromagnetic induction, and the showers 13 are actuated, in a manner operatively associated to the inductors 6,8 and which is obvious for those skilled in the art and therefore not described in detail, for producing a localized hardening of the track 4.
  • this also includes the further step of actuating the third inductor 40 by the means 42 which electrically feed it, third inductor 40 which is held angularly fixed by the means 10 in a position immediately adjacent to the second side 23 of the first inductor 6 and facing parallel to the track 4, when the second inductor 8 is at the aforesaid, relatively short, prefixed distance K from the second side 23 of the first inductor 6.
  • this includes instead the additional step of actuating the inductors 6,8, by the means 50, so that at least when the second inductor 8 is in a position immediately adjacent to the second side 23 of the first inductor 6, the magnetic fluxes of the first and second inductor 6,8 are at least partially concatenated through a portion of the thrust block 3 locally facing the inductors 6,8 (figure 10) .
  • step is performed by circulating, by the means 50, an electric feeding current I of the inductors 6,8 in an opposite sense in the inductors 6,8 themself.
  • the hardening method according to the invention further includes the step of configuring the inductors 6,8 in a first, asymmetrical manner in the relative direction of rotation with respect to the thrust block 3, and so that, when the second inductor 8 is in a position immediately adjacent to the second side 23 of the first inductor 6, the magnetic fluxes of the first and second inductor 6,8 are at least partially concatenated in a portion of the thrust block 3 locally facing the inductors 6,8 themselves.
  • the inductors 6,8 are provided with F-shaped (or C-shaped ,L-shaped, E- shaped, T-shaped) concentrators 61,81, having the arms of the asymmetric shape facing in use towards the track 4 and oriented so that the open side of the shape defined by the concentrator 61 corresponds to the second side 23 of the inductor 6; and so that when the inductor 8 is in a position adjacent to the side 23 of the inductor 6 the shapes defined by the concentrators 61,81 are arranged in a specularly symmetric manner towards the thrust block 3, with the adjacent open sides, as shown in figure 9.
  • F-shaped (or C-shaped ,L-shaped, E- shaped, T-shaped) concentrators 61,81 having the arms of the asymmetric shape facing in use towards the track 4 and oriented so that the open side of the shape defined by the concentrator 61 corresponds to the second side 23 of the inductor 6; and so that when the inductor 8 is in a position adjacent to the side 23 of the
  • the optimal hardening of the element 3 is not only obtained by means of the optimal management of the heating by induction, as described hereto, but also by means of an optimal management of the cooling (which produces the hardening) by means of the showers 13.
  • showers 13b and 13a are installed on the inductors 6 and 8, respectively; each shower 13a, b, is installed over the corresponding inductor 8,6, on the opposite side to the element to be hardened 3, at a corresponding end side of the corresponding inductor, i.e.
  • At least one third shower 13d (or several showers 13d in sequence) is always present, arranged in one or more fixed positions, e.g. integrally carried by the same positioning means 10 of the fixed inductor 6 in a position adjacent to the second side 23 of the first inductor 6, and fan- shaped i.e. each shower 13d extends along a non-negligible angular segment of the element to be hardened 3, segment which in this non- limitative case shown, of circumferential length L (figure 7) either equal to or greater than the sum of the circumferential extension lengths Ll, L2 and L3 of the inductors 8, 6 and 40 (if present) .
  • the shower 13d is actuated at the end of the heating cycle of the element 3 to be hardened; specifically, when the - inductor 8 completes its stroke and reaches the stroke end position (e.g. figures 8, 9, 10) and once the heating cycle has been ended, all the inductors 6,8 and 40 (if present) are deactivated, while the showers 13a, b are held in operation; therefore, the rotation of both the inductor 8 and the element 3 to be hardened is inverted, always keeping the previous speed ratio, thereby the inductor 8 rotates at a speed double that of the element 3, until the inductor 8 is moved away from the side 23 of the inductor ⁇ of a displacement equal to the circumferential length L of the shower 13d; at this point, the inductor 8 and the element 3 are stopped and the shower 13d is activated, until the hardening of the element 3 is completed also in the 'transition zone' , i.e.
  • the hardening method and device according to the invention are very versatile and simple and that the method and device may be implemented simply and cost-effectively with compact dimensions. Furthermore, the heating profile of the thrust block 3 which- is obtained in virtue of the 'tracking system' ' adopted for handling the thrust block 3 and one of the inductors (and the corresponding showers 13) surprisingly allows to obtain high heating uniformity and, above all, to ensure the maintenance of the minimum hardening depth T everywhere on the thrust block 3, with the essential elimination of the ' soft zone' .
  • the third shower 13d over the 'transition zone' which would otherwise tend to form the 'soft zone' intervenes (i.e. is actuated) only after a rapid displacement of the inductors for 'clearing' the latter hardening zone, displacement which may occur in the previously described manner and/or by means of lateral or vertical displacements of the inductors 6,8 and 40 (if present) made so as to move them away from the wet zone of the shower 13d.

Abstract

A method and device for induction hardening rolling tracks (4)of bearing thrust blocks (3). At least two inductors are used (6, 8) initially arranged in tandem, which are held at a prefixed distance from a surface (2) of the track and parallelly to the same; the thrust block (3) is rotated at a first angular speed (V1) with respect to a first inductor (6), held fixed, while a second inductor (8) is rotated in the same direction as the thrust block but at a second angular speed (V2), double the first, so as to leave a first side (22) of the first inductor (6) and, essentially after a complete rotation, arrange itself sided to a second side (23) of the first inductor, on the side opposite to the first; simultaneously, the inductors are electrically fed and at least one cooling shower (13a, b,d), operatively connected to the other inductors (6, 8), is actuated.

Description

METHOD AND DEVICE FOR LOCALIZED INDUCTION HARDENING TREATMENT OF MECHANICAL COMPONENTS, SPECIFICALLY THRUST BLOCKS FOR LARGE-SIZED ROLLING BEARINGS
Field of the art
The present invention relates to a method and device for performing a localized induction hardening treatment on mechanical components, specifically for hardening large-sized rolling bearing thrust block tracks.
Prior art
The induction hardening treatment of large- sized thrust blocks bearings tracks displays several problems, the most important of which are the relatively slow speed of the hardening process, which does not exceed 300-350 mm/min, inaccuracies and difficulties to obtain a desired hardening profile, which ideally requires different hardening intensities at different zones of the tracks, the need to have inductors which perfectly 'mimic' the transversal profile of the track and which therefore cannot be used for even only slightly different thrust blocks, and the formation of a partial tempering zone, known as 'soft zone' .
Indeed, the induction hardening process is typically performed as diagrammatically shown in figure 2, wherein one or preferably a pair of inductors A, B heat the thrust block, which is rotated with respect to the inductors in a prefixed direction of rotation; downstream of the inductors, where the term 'downstream' refers to the sense of rotation of the thrust block, a cooling shower C, which performs the hardening (quenching) itself, is arranged.
At present, all these problems have been only partially solved in a satisfactory manner, to the detriment of either poor or no flexibility of the employed machinery, and of a high cost and considerable complexity of the same. Specifically, a method and device is known from WO2006/087152A2 , wherein the thrust block is held still and two inductors, initially arranged side-by-side in tandem, are simultaneously rotated in an opposite sense, with respect to the thrust block, following the profile thereof. Such a hardening method, although allowing to accelerate the hardening process time, however displays the drawback of requiring an extremely complex machinery, which is costly to be implemented. Furthermore, it only partially solves the problem of avoiding the formation of soft zones.
It is thus the object of the present invention to provide an alternative induction hardening method and device, which overcome the above-described drawbacks, specifically capable of ensuring high production rates and high heating uniformity of the treated parts, regardless of the shape and size of the same, displaying at the same time small dimensions and low construction and running costs, with considerable reduction, or even complete elimination, of the soft zones. Summary of the invention
The aforesaid and other objects are reached by the present invention as defined in claims 1 and 11.
Specifically, the method according to the invention consists in performing a localized induction hardening treatment of large- sized bearing thrust blocks using at least . a first and a second inductors at least initially arranged reciprocally in tandem with respect to the track to be hardened, which are held at a prefixed distance from the surface of the track and parallelly to the surface itself; and including, in combination, the steps of : - rotating the thrust block at a first angular speed with respect to the first inductor, which is instead held angularly fixed; simultaneously, rotating the second inductor about the thrust block and in the same sense of rotation as the thrust block but at a second angular speed, faster than the first, so as to leave a first side of the first inductor and, once a complete rotation has been performed with respect thereto, arranging itself side-by-side to a second side of the first inductor, on the side opposite to the first side; simultaneously with the preceding steps, electrically feeding said inductors so as to produce a localized heating of the thrust block track by- electromagnetic induction, and actuating quenching means of the thrust block to produce a localized hardening of the track in a manner operatively associated to the inductors .
Surprisingly, in this manner, a high heating uniformity is obtained throughout the angular extension of the element to be hardened, thus ensuring a hardening profile which is sufficiently uniform and, above all, which displays a prefixed, ensured minimum hardening depth.
The device for implementing the method of the invention includes, according to a further aspect of the invention, at least a first and a second inductors arranged at least in a first operating position reciprocally in tandem with respect to a surface of an annular element to be hardened, positioning means for keeping the inductors parallel to and at a prefixed distance from the surface of the annular element to be hardened, and quenching means of the annular element operatively associated to the inductors for producing a localized hardening of the aforesaid surface of the annular element to be hardened; and furthermore it includes: first handling means to rotate the annular element to be hardened at a first angular speed about the symmetry axis thereof in front of the first inductor, which is carried by positioning means in a fixed angular position with respect to the annular element to be hardened; and second handling means to rotate the second inductor, at a second angular speed faster than the first and concentrically to the annular element to be hardened, in the same sense of rotation as the annular element to be hardened, so as to leave a first side of the first inductor and, once a complete rotation has been performed with respect thereto, and arranged side-by-side in tandem, in a second operating position of the inductors, on a second side of the first inductor, on the side opposite to the first side.
Furthermore, the method and device according to the invention allow to easily implement further measures to increase the hardening uniformity and in actual fact to eliminate the soft zone, preventing the occurrence of localized tempering.
Specifically, a third inductor may be provided arranged angularly fixed in a position immediately adjacent to the second side of the first inductor and in use facing and parallel to the surface of the annular element to be hardened; and means for actuating the third inductor only when the second inductor is at a prefixed, relatively short distance from the second side of the first inductor. Alternatively to the third injector, handling means, of the first and second_ inductors may be provided adapted in use to direct the electric current through the inductors so that, at least when the second inductor is in a position immediately adjacent to the second side of the first inductor, the magnetic fluxes of the first and second inductors are at least partially concatenated through a portion of the annular element to be hardened locally facing the inductors themselves.
Alternatively or in addition to this aspect of the invention, the first and the second inductors may be asymmetrically configured in the relative direction of rotation of the annular element to be hardened, so as to obtain an effect similar to the preceding one and, in essence, to apply a more effective magnetic field to the element to be hardened in order to obtain the required heating profile; specifically, the inductors are provided with profiled concentrators, on a plane perpendicular to the surface to be hardened, with an asymmetric shape on such a plane, such as an F- shape, a C-shape, a T-shape, an E-shape, an L-shape, having for example asymmetric arms of such a shape facing in use the element to be hardened and wherein a first 'open' side of the concentrator of the first inductor corresponds to the second side of the first inductor; and wherein when the second inductor is in a position adjacent to the second side of the first inductor, the shapes defined by the concentrators of the first and of the second inductors are specularly and symmetrically arranged towards the annular element to be hardened. Brief description of the figures
Further objects and advantages of the invention will be apparent from the following description of an embodiment provided only by way of non- limitative example and with reference to the accompanying drawings, in which: figure 1 diagrammatically depicts an annular element to be hardened, shown in radial section and a detail of the hardening device according to the invention; figure 2 diagrammatically "shows an induction hardening method according to the known art; figures from 3 to 6 diagrammatically show corresponding top plan λ^iews of the induction hardening device according to the invention shown in different configurations each time, corresponding to different steps of the hardening method according to the invention; figures 7 and 8 diagrammatically show plan views of a hardening device acco'rding to the invention during some additional, optional steps of the method according to the invention; and figures 9 and 10 diagrammatically show in elevation and radial section views, similar details of the hardening device in figures 3-6 during the implementation of the method according to the invention. Detailed description With reference to figure 1 and figures from 3 to 6 , numeral 1 indicates as a whole a device for performing a localized induction hardening treatment on a surface 2 of an annular element 3; specifically, the element 3 consists in large-sized bearing thrust blocks and the surface 2 -belongs to a rolling track 4 of a thrust block 3.
As will be explained below, the device 1 is constructed so as to ensure that a minimum prefixed hardening depth T is obtained on the track 4 along the entire angular extension of the element 3 and includes at least a first inductor 6 and a second inductor 8 at least initially arranged in a first operating position thereof, shown in top plan view in figure 3, reciprocally in tandem with respect to the surface 2 of the annular element 3 to be hardened, i.e. as in the state of the art shown in figure 2, where A and B indicate two inductors arranged in tandem, C indicates a cooling shower arranged in turn in tandem with respect to the inductor B, and D indicates the element to be hardened.
The device 1 further includes positioning means 10,12 (known, figure 3, and only indicated by a dashed line and as blocks for simplicity) for keeping in use the inductors 6,8 parallel to and at a prefixed distance from the surface 2 of the annular- element 3 to be hardened-, and quenching means 13 of the annular element 3, e.g. of the type of the shower C of the state of the art, operatively associated in the manner shown below to the inductors 6,8 to produce a localized hardening of the surface 2 of the annular element 3 to be hardened; e.g. each inductor 6,8 may be integrally provided with a shower 13b,13~a respectively, or one or two showers 13 may be carried by the positioning means 10,12, even independently from the inductors 6,8.
The positioning means 10,12 preferably consist, in . turn, of automated arms or towers, with three, four or more numerically controlled axes, well known to those skilled in the art and which therefore are not described in detail.
According to a first aspect of the invention, the device 1 further includes in combination: first handling means 20 to rotate, at a first angular speed Vl
(indicated in a sense and direction of the arrow in figure 3) and about a symmetry axis X thereof (figure
1), the annular element 3 in front of the inductor 6, which is carried by the positioning means 10 in a fixed angular position with respect to the annular element 3 to be hardened and to the rotation axis X of the same; and second handling means 21 to rotate the inductor 8 at a second angular speed V2 (indicated in a sense and direction of the corresponding arrow in figure 3) concentrically to the annular element 3 to be hardened, i.e. also about the axis X, in the same sense of rotation as the annular element to be hardened 3.
According to the invention, the angular speed V2 is different from Vl and specifically is higher in module and identical in direction and sense to Vl, so that, in
■5 use, with the handling means 20 and 21 in operation, the second inductor 8 is forced to leave its position in tandem with the first inductor 6, moving away from it towards the part of one side 22 of the inductor 6 itself
. . and, once a complete rotation has been essentially 0 performed with- respect thereto, is forced to side, in a second operating position, the inductors 6,8, on a second side 23 of the first inductor 6, again in tandem with the same but on the opposite side with respect to the first side 22, according to the sequence 5 diagrammatically shown in figures 4, 5 and 6.
The first and second handling means 20 and 21 are reciprocally and operatively connected by means of a device 26 (figure 1) adapted to ensure an either constant or even variable ratio (e.g. according to the 0 relative angular position of the inductors 6,8) , or however desired, between the angular speeds Vl and V2 ; preferably, such a ratio is constant and such that
V2 = 2 -Vl 5 i.e. it is such that the angular rotation speed V2 of the inductor 8 is double the rotation speed of the element (thrust block) 3 to be hardened.
In this case, the handling means 20 consist of a rotating table 30 (figures 1 and 3) actuated by motor means 31, while the handling means 21 include an arm 33 arranged radially oriented with respect to the annular element (thrust block) 3 to be hardened, and motor means 34 for the arm 33 radially arranged in use within the annular element 3 to be hardened, e.g. either over or inside the rotating table 30 (in the latter case, if the table 30 is also annular) ; the motor means 31 and 34 may either be reciprocally independent, in which case the device 26 consists of an electronic control unit, or may be operated by a common motor, in which case the device 26 is a mechanical transmission device of the motion between the motor means 31 and the motor means 34.
Figures 7 and 8 show an embodiment Ib of the device 1 just described, which in addition to the inductors 6,8 includes a third inductor 40 angularly arranged fixed in a position immediately adjacent to the second side 23 of the first inductor 6 and in use facing and parallel to the surface 2 of the annular element 3 to be hardened, thus in tandem with the inductor 6 with respect to the thrust block 3 and upstream of the latter with respect to the sense of rotation of the thrust block 3. The device Ib further includes means 42, of known type (and thus diagrammatically indicated by a block) , for actuating the third inductor 40, i.e. for feeding an electric current therein at a predetermined voltage so as to make the inductor 40 generate an electromagnetic field which concatenates with the thrust block 3 on the surface 2 thus causing a localized heating by electromagnetic induction of the track 4.
According to the invention, the means 42 are adapted (e.g. because they are provided with an electronic control unit connected to specific sensors - not shown - of the angular position of the rotating inductor 8, i.e. of the arm 33) to actuate the inductor 40 in the aforesaid manner only when the second inductor 8 is at a prefixed, relatively short distance K from the second side 23 of the first inductor 6. 'Relatively short' hereinafter means a distance equal to only a fraction of a fourth of the circumference of the element 3.
Alternatively to this measure, not always convenient because a third inductor is required, with consequent costs and dimensions correlated thereto, the device 1, thus based on only two inductors 6 and 8, may be provided (figure 10) with actuating means 50 of the inductors 6,8 (where the term 'actuating' means what previously described with regards to the actuating means 42 of the inductor 40) , adapted to direct, in use, the electric current through such inductors 6,8 so that at least partially when the second inductor 8 is in a position immediately adjacent to the second side 23 of the first inductor 6, the magnetic fluxes of the first and second inductors 6,8 are at least partially concatenated through a portion of the annular element 3 in that moment facing the inductors 6,8, as shown by means of the flux lines F illustrated with a dashed line in figure 10.
Specifically, the actuating means 50 of the inductors 6,8 are adapted to circulate, always or only after a given moment, the electric current. I in the inductors 6,8 in an opposite sense, as diagrammatically shown in figure 10, where the current I entering the plane of the sheet is depicted by a St. Andrew's cross, while the current I exiting from the plane of the sheet is depicted by a dot, so that the current I on the side 23 of the inductor 6 circulates in the same sense as the current I which circulates on the side of the inductor 8 immediately adjacent to the side 23 corresponding to the stroke end of the inductor 8 which, as previously mentioned, corresponds to that which follows an essentially complete rotation of -the " inductor 8 about the axis X, thus to a complete rotation decreased by the dimensions of the inductor 6 measured in the direction of rotation of the inductor 8.
With reference to figure 9, either alternatively or in addition to the features now described with reference to figure 10, the inductors 6 and 8 of the device 1 may be configured asymmetrically in the relative direction of rotation with respect to the annular element 3 to be hardened, so that, when the second inductor 8 is in a position immediately adjacent to the second side 23 of the first inductor 6, the magnetic fluxes of the first and the second inductor 6,8 are at least partially concatenated through the annular element 3 to be hardened as diagrammaticalIy shown by the dashed flux line F in figure 9.
In the non- limitative example shown in figure 9, the inductors 6,8 are provided with shaped concentrators 61,81, on a plane perpendicular to the surface 2 to be hardened, i.e. in radial section (with reference to axis X) , with an asymmetric shape on such a plane, such as an F- shape, a C-shape, a T- shape, an E-shape, an L- shape (in the illustrated non- limitative example, the shape is as an F) , having, for example, the asymmetric arms of such a shape facing in use towards the element 3 to be hardened and wherein a first 'open' side of the concentrator of the first inductor displays the arms thereof, in the illustrated case defined by transverse portions 62,63 and 82,83 of the F-shaped concentrators 61,81, facing in use towards the track 4 and oriented so that, on one side, the open side of the F formed by the concentrator 61 corresponds to the second side 23 of the inductor 6; and so that, when the second inductor 8 is in a position adjacent to the second side 23 of the inductor 6 (i.e. in its first defined stroke end position) , the shapes, in this case the F-shapes, defined by the concentrators 61 and 81 are specularly and symmetrically arranged towards the annular element 3 to be hardened, with the open side portions reciprocally adjacent and the portions 62,82 arranged on opposite sides.
In virtue of the device 1 hereto described, a method for performing a localized induction hardening treatment of rolling- tracks 4 of large- sized bearing thrust blocks 3 -may be implemented, according to the invention, ensuring a prefixed minimum hardening depth
T, wherein at least the inductors 6,8 or possibly the inductors 6,8 plus the inductor 40 are used (device Ib) .
Firstly, by appropriately actuating the positioning means 10 and 12, the inductors 6 and 8 are arranged reciprocally in tandem along the track 4 to be hardened, with the inductor 8 arranged adjacent to the side 22 of the inductor 6; subsequently, again by keeping the inductors 6,8, at a prefixed distance from the surface 2 of the track 4 and" parallel to the surface 2 itself by means of the positioning means 10,12, the thrust block 3 is rotated about the axis X, by means of the table 30, at a first angular speed Vl, while the inductor 6 is held angularly fixed. According to the main aspect of the method of the invention, simultaneously to this step of rotating the thrust block 3, the second inductor 8 is also rotated about the axis X by means of the arm 33, thus concentrically about the thrust block 3, in the same sense of rotation as the thrust block 3 but at a second angular speed V2 faster than Vl, preferably chosen equal to double Vl, so as to leave the first side 22 of the inductor' 6 and, once a complete rotation has been essentially performed with respect thereto (i.e. a complete rotation decreased by the dimensions of theinductor 6 in the direction of rotation of the inductor 8) , arrange side-by- side in tandem to the second side 23 of the inductor 6, on the side opposite to the first side 22.
Simultaneously to the preceding steps, a step of electrically feeding the inductors 6,8, is performed e.g. by means of the actuating means 50, so as to produce a localized heating of the track 4 of the thrust block 3 by electromagnetic induction, and the showers 13 are actuated, in a manner operatively associated to the inductors 6,8 and which is obvious for those skilled in the art and therefore not described in detail, for producing a localized hardening of the track 4.
According to a first possible preferred embodiment of the method of the invention, this also includes the further step of actuating the third inductor 40 by the means 42 which electrically feed it, third inductor 40 which is held angularly fixed by the means 10 in a position immediately adjacent to the second side 23 of the first inductor 6 and facing parallel to the track 4, when the second inductor 8 is at the aforesaid, relatively short, prefixed distance K from the second side 23 of the first inductor 6. According to an alternative, further possible preferred variant of the method of the invention, this includes instead the additional step of actuating the inductors 6,8, by the means 50, so that at least when the second inductor 8 is in a position immediately adjacent to the second side 23 of the first inductor 6, the magnetic fluxes of the first and second inductor 6,8 are at least partially concatenated through a portion of the thrust block 3 locally facing the inductors 6,8 (figure 10) . According to the invention, such as step is performed by circulating, by the means 50, an electric feeding current I of the inductors 6,8 in an opposite sense in the inductors 6,8 themself.
Alternatively or in addition to the preceding step, the hardening method according to the invention further includes the step of configuring the inductors 6,8 in a first, asymmetrical manner in the relative direction of rotation with respect to the thrust block 3, and so that, when the second inductor 8 is in a position immediately adjacent to the second side 23 of the first inductor 6, the magnetic fluxes of the first and second inductor 6,8 are at least partially concatenated in a portion of the thrust block 3 locally facing the inductors 6,8 themselves.
In order to implement this step, the inductors 6,8 are provided with F-shaped (or C-shaped ,L-shaped, E- shaped, T-shaped) concentrators 61,81, having the arms of the asymmetric shape facing in use towards the track 4 and oriented so that the open side of the shape defined by the concentrator 61 corresponds to the second side 23 of the inductor 6; and so that when the inductor 8 is in a position adjacent to the side 23 of the inductor 6 the shapes defined by the concentrators 61,81 are arranged in a specularly symmetric manner towards the thrust block 3, with the adjacent open sides, as shown in figure 9. In order to obtain such a configuration in this relative stroke end position (second operating position - figure 6) of the two inductors 6,8, in the initial position shown in figure 3 (first operating position) , they should obviously have the concentrators 61,81 oriented with the adjacent portions 62,82.
According to a further aspect of the invention, the optimal hardening of the element 3 is not only obtained by means of the optimal management of the heating by induction, as described hereto, but also by means of an optimal management of the cooling (which produces the hardening) by means of the showers 13.
Specifically, as previously described, showers 13b and 13a, only diagrammaticalIy shown as blocks in figures 3-6 and shown again diagrammatically but in the real installation positions in figures 7-10, are installed on the inductors 6 and 8, respectively; each shower 13a, b, is installed over the corresponding inductor 8,6, on the opposite side to the element to be hardened 3, at a corresponding end side of the corresponding inductor, i.e. the shower 13b on the side22 of the inductor 6, and the shower 13a on a side 220 of the inductor 8, which side 220 is adjacent to the side 22 in the first tandem operating position of the inductors 6,8 which are arranged on the side opposite to the side 22 (and also to the side 23 and the third inductor 40, if present) in the second tandem operating position of the inductors 6,8, corresponding to the stroke end position of the movable inductor 8.
Furthermore, according to the invention, at least one third shower 13d (or several showers 13d in sequence) is always present, arranged in one or more fixed positions, e.g. integrally carried by the same positioning means 10 of the fixed inductor 6 in a position adjacent to the second side 23 of the first inductor 6, and fan- shaped i.e. each shower 13d extends along a non-negligible angular segment of the element to be hardened 3, segment which in this non- limitative case shown, of circumferential length L (figure 7) either equal to or greater than the sum of the circumferential extension lengths Ll, L2 and L3 of the inductors 8, 6 and 40 (if present) .
According to an aspect of the invention, the shower 13d is actuated at the end of the heating cycle of the element 3 to be hardened; specifically, when the - inductor 8 completes its stroke and reaches the stroke end position (e.g. figures 8, 9, 10) and once the heating cycle has been ended, all the inductors 6,8 and 40 (if present) are deactivated, while the showers 13a, b are held in operation; therefore, the rotation of both the inductor 8 and the element 3 to be hardened is inverted, always keeping the previous speed ratio, thereby the inductor 8 rotates at a speed double that of the element 3, until the inductor 8 is moved away from the side 23 of the inductor β of a displacement equal to the circumferential length L of the shower 13d; at this point, the inductor 8 and the element 3 are stopped and the shower 13d is activated, until the hardening of the element 3 is completed also in the 'transition zone' , i.e. the zone which is heated in an optimal manner by the third inductor 40 (if present) or by the special configuration and/or so as to operate the inductors 6,8 (figures 9,10) . At this point, all the showers 13 are deactivated and the inductor 8 is returned to the starting position, adjacent to the side 22 of the inductor 6.
From the above described, it is apparent that the hardening method and device according to the invention are very versatile and simple and that the method and device may be implemented simply and cost-effectively with compact dimensions. Furthermore, the heating profile of the thrust block 3 which- is obtained in virtue of the 'tracking system'' adopted for handling the thrust block 3 and one of the inductors (and the corresponding showers 13) surprisingly allows to obtain high heating uniformity and, above all, to ensure the maintenance of the minimum hardening depth T everywhere on the thrust block 3, with the essential elimination of the ' soft zone' .
As seen, the third shower 13d over the 'transition zone' which would otherwise tend to form the 'soft zone' intervenes (i.e. is actuated) only after a rapid displacement of the inductors for 'clearing' the latter hardening zone, displacement which may occur in the previously described manner and/or by means of lateral or vertical displacements of the inductors 6,8 and 40 (if present) made so as to move them away from the wet zone of the shower 13d.

Claims

1. A method for performing a localized induction hardening treatment of rolling tracks (4) of large-sized bearing thrust blocks (3), ensuring a minimum prefixed hardening depth (T) , in which at least a first (6) and a second (8) inductors are used, at least initially arranged in a first operating position, reciprocally in tandem with respect to the track (4) to be hardened, which are held at a prefixed distance from a surface (2) of the track and parallelly to the surface itself; characterized in that it includes the steps of:
- rotating the thrust block (3) at a first angular speed (Vl) with respect to the first inductor (6), which is instead held angularly fixed; - simultaneously, rotating the second inductor (8) about the thrust block (3) and in the same sense of rotation as the thrust block but at a second angular speed (V2) , faster than the first, so as to leave a first side (22) of the first inductor (6) and, once a complete rotation has been essentially performed with respect thereto, arrange itself side-by-side, in a second tandem operating position, to a second side (23) on the first inductor (6) , on the side opposite to the first side (22) ; - simultaneously with the preceding steps, electrically feeding said inductors (6,8) so as to produce a localized heating of the track (4) of the thrust block (3) by electromagnetic induction and actuating, in a manner- operatively associated to the inductors, quenching means (13) of the thrust block (3) to "produce a localized hardening of the track (4) .
2. A method according to claim 1, characterized in that ≤aid second angular speed (V2) for handling the second inductor (8) is chosen so as to be equal to double the first angular speed (Vl) for handling the thrust block (3) . .-
3. A method according to claim 1 or 2, characterized in that said second inductor (8) is rotated relatively to the first inductor (β) and to said thrust block (3) so as to perform, concentrically to the thrust block (3) , a complete one turn rotation decreased by the dimensions of the first inductor (6) in the direction of rotation of the second inductor (8) .
4. A method according to any one of the preceding claims, characterized in that it further includes the step of: -- actuating, i.e. electrically feeding, a third inductor (40) , while it is held angularly fixed in a position immediately adjacent to said second side (23) of the first inductor (6) and facing parallelly to said track (4) , when the second inductor (8) is at a relatively short, prefixed distance (K) from the second side (23) of the first inductor.
5. A method according to claims from 1 to 3 , characterized in that it further includes the step of:
- actuating said first and second inductors (6,8) so that, at least when the second inductor (8) is in a position immediately adjacent to the second side (23) of the first inductor, the magnetic fluxes of the first and second inductors are at least partially concatenated through a portion of said thrust block (3) locally facing said inductors (6,8) .
6. A method according to claim 5, characterized in that an electric feeding current (I) is circulated in a sense opposite to said first and second inductors (6,8) .
7. A method according to claims from 1 to 6 , characterized in that it further includes the step of: - asymmetrically configuring said first and second inductors (6,8) in the relative direction of rotation about said thrust block (3) and so that, when the second inductor (8) is in a position immediately adjacent to the second side (23) of the first inductor, the magnetic fluxes of the first and second inductors are at least partially concatenated through a portion of said thrust block (3) locally facing said inductors (6,8) .
8. A method according to claim 7, characterized in that said first and second inductors (6,8) are provided with concentrators (61,81) having a shape chosen from the group consisting of: F-shaped, C-shaped, T-shaped, L- shaped, E- shaped, the corresponding arms of which are facing in use the track (4) and orientated so that:
(i)- an open side of the concentrator (61) of the first inductor (6) corresponds to a second side (23) of the first inductor;
(ii)- when the second inductor (8) is in a position adjacent to said second side (23) of the first inductor, the shapes defined by the concentrators (61,81) of the first and second inductors (6,8) are arranged in a specularly symmetric manner towards the thrust block (3) .
9. A method according to any one of the preceding claims, characterized in that said quenching means (13) are implemented as showers (13b, 13a) integrally carried by said first (6) and second (8) inductors, respectively on the first side (22) of the first inductor (6) and on a side (220) of the second inductor (8) immediately adjacent to the first side (22) in said first operating position of the inductors (6,8) ;. and as a third shower (13d) positioned fixed with respect to the thrust block (3) and which is actuated once the inductors (6,8) have been rapidly displaced so as to move them away from the wet zone of said third shower (13d) .
10. A method according to claim 9, characterized in that the second inductor (8) , once the second operating position has been reached, is rotated in the opposite "sense, with the inductors (6,8) deactivated but with the corresponding showers (13b, 13a) activated, to move it away from the second side (23) of the first actuator (6) by a circumferential segment, with respect to the thrust block (3) , of a length (L) equal to the circumferential extension of said third shower (13d) and equal to at least the sum of the lengths of circumferential extension (Ll , L2 , L3) of said first and second inductors (6,8) and of a possible third inductor
(40) , fixed and adjacent to the second side (23) of the first inductor (6) .
11. A device (l;lb) for performing a localized induction hardening treatment on a surface (2) of an annular element (3) , specifically of rolling tracks (4) for large-sized bearing thrust blocks (3) , ensuring a minimum prefixed hardening depth (T) , including at least a first (6) and a second (8) "inductors arranged, in a first operating position, reciprocally in tandem with respect to said surface (2) of the annular element to be hardened, positioning means (10,12) for keeping said inductors (6,8) parallel to and at a prefixed distance from said surface (2) of the annular element to be hardened, and quenching means (13) of the annular element operatively associated to said inductors (6,8) to produce a localized hardening of said surface (2) of the annular element to be hardened; characterized in that it includes in combination:
- first handling means (20) to rotate said annular element (3) to be hardened at a first angular speed (Vl) about the symmetry axis (X) thereof in front of the first inductor (6) , which is carried by said positioning means (10) in an angularly fixed position with respect to the annular element (3) to be hardened; and.
- second handling means (21) to rotate said -second inductor (8) at a second angular speed (V2) , faster than the first, and concentrically to said annular element (3) to be hardened, in the same sense of rotation as the. annular element (3) to be hardened, so as to leave a first side (22) of the first inductor and, once a complete rotation has been essentially performed with respect thereto, arrange itself in a second tandem operating position of the inductors (6,8) on a second side (23) of the first inductor, on the side opposite to the first side.
12. A device (l;lb) according to claim 11, characterized in that said first and second handling means (20,21) are reciprocally and operatively connected; and in that said quenching means (13) consist of corresponding showers (13b, 13a) integrally carried by said inductors (6,8) and in a third shower (13d) carried fixed with respect to the element (3) to be hardened in an angular position adjacent to the second side (23) of the first inductor (6) and having a circumferential extension with respect to the element to be hardened, at least equal to the sum of the circumferential lengths of all the present inductors (6,8; 40) .
13. A device (l;lb) according to claim 12, characterized in that said second handling means (21) are adapted to rotate said second inductor (8) at a speed equal to double the rotation speed of the annular element to be hardened (3) with respect to the first inductor (6) .
14. A device (l;lb) according to any one of the claims from 11 to 13, characterized in that said second handling means (21) include an arm (33) radially oriented with respect to said annular element (3) to be hardened and motor means (34) for said arm .(33) radially arranged in use within the annular element (3) to be hardened .
15. A device (Ib) according to any one of the claims from 11 to 14, characterized in that it includes: a third inductor (40) arranged angularly fixed in a position immediately adjacent to said second side (23) of the first inductor (6) and in use facing parallelly to said surface (2) of the annular element to be hardened; and means (42) for actuating the third inductor (40) only when the second inductor (8) is at a prefixed, relatively short distance (K) from the second side (23) of the first inductor.
16. A device (1) according to any one of the claims from 11 to 14, characterized in that it includes: - actuating means (50) of said first and second inductors (6,8) adapted to direct the electric current (I) through said inductors so that, at least when the second inductor (8) is in a position immediately- adjacent to the second side (23) of the first inductor, the magnetic fluxes of the first and second inductors are at least partially concatenated through a portion of said annular element (3) to be. hardened locally facing said inductors (6,8) .
17. A device (1) according to any one of the - claims from 11 to 16, characterized in that said first and second inductors (6,8) are asymmetrically configured in the direction of rotation relative to said annular element (3) to be hardened, and such that when the second inductor element (8) is in a position immediately adjacent to the second side (23) of the first inductor, the magnetic fluxes of the first and second inductors are concatenated at least partially through the annular element (3) to be hardened.
PCT/IT2008/000475 2008-07-15 2008-07-15 Method and device for localized induction hardening treatment of mechanical components, specifically thrust blocks for large-sized rolling bearings WO2010007635A1 (en)

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JP2023507235A (en) * 2020-02-10 2023-02-21 エスエムエス エロテルム ゲゼルシャフト ミット ベシュレンクテル ハフツング Surface layer induction hardening method
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WO2022049150A1 (en) * 2020-09-01 2022-03-10 Sms Elotherm Gmbh Method and device for inductively hardening an edge layer

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