EP0081400B1 - Dispositif de chauffage par induction magnétique de produits métalliques rectangulaires plats défilant dans le sens de leur longueur - Google Patents

Dispositif de chauffage par induction magnétique de produits métalliques rectangulaires plats défilant dans le sens de leur longueur Download PDF

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Publication number
EP0081400B1
EP0081400B1 EP82401998A EP82401998A EP0081400B1 EP 0081400 B1 EP0081400 B1 EP 0081400B1 EP 82401998 A EP82401998 A EP 82401998A EP 82401998 A EP82401998 A EP 82401998A EP 0081400 B1 EP0081400 B1 EP 0081400B1
Authority
EP
European Patent Office
Prior art keywords
inductor
heating device
pole
axis
polar
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP82401998A
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German (de)
English (en)
French (fr)
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EP0081400A1 (fr
Inventor
Jean Maurice
Roger Travers
Jean-Paul Camus
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Alstom SA
Original Assignee
Alstom SA
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Filing date
Publication date
Application filed by Alstom SA filed Critical Alstom SA
Publication of EP0081400A1 publication Critical patent/EP0081400A1/fr
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/10—Induction heating apparatus, other than furnaces, for specific applications
    • H05B6/101—Induction heating apparatus, other than furnaces, for specific applications for local heating of metal pieces
    • H05B6/102—Induction heating apparatus, other than furnaces, for specific applications for local heating of metal pieces the metal pieces being rotated while induction heated
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/36—Coil arrangements
    • H05B6/365—Coil arrangements using supplementary conductive or ferromagnetic pieces

Definitions

  • the present invention relates to a device for heating by magnetic induction of flat rectangular metal products running in the direction of their length, of the type comprising at least one inductor capable of producing a magnetic field of constant intensity, but adjustable, oriented substantially perpendicular to a large face of the metal product to be heated, said inductor being rotatably mounted about an axis perpendicular to said large face of the metal product and comprising at least two magnetic poles having polar surfaces oriented towards said large face are parallel to these, and scanning an annular area when the inductor rotates.
  • the magnetic poles can be formed by permanent magnets, electromagnets or a combination of permanent magnets and electromagnets.
  • the inductor (s) can be placed outside a tunnel made of refractory material and permeable to the magnetic field, inside which pass the metallic products to be heated.
  • the present invention therefore aims to solve this problem by providing an improved device for magnetic induction heating to improve the uniformity of the heating in the transverse direction of the metal products running in the direction of their length, and this whatever the width of metal products within a given width range.
  • the magnetic induction heating device is characterized in that the pole surface of each pole has the shape of a curvilinear triangle having a vertex directed towards the axis of rotation of the inductor, two concave sides which are symmetrical with respect to a straight line passing through said vertex and perpendicular to said axis, and a convex side in an arc centered on said axis and whose radius of curvature is substantially equal to the outside radius of the annular zone swept by polar surfaces of the poles.
  • the conventional magnetic induction heating device which is shown diagrammatically in FIG. 1 and to which the present invention can be applied comprises, for example, two inductors 1 and 2 arranged respectively above and below the metal product 3 to be heated, for example a slab, facing the large faces of the slab 3, the latter being driven by a continuous movement in a direction perpendicular to the plane of the figure, that is to say in the direction of its length.
  • each of the two inductors comprises several magnetic poles, for example two magnetic poles 4.
  • the poles 4 can be constituted by permanent magnets, by wound poles whose windings are supplied with direct current (electromagnet), or by permanent magnets surrounded by windings which can be supplied with direct current.
  • the intensity of the direct current can be adjusted in a known manner in order to adjust the intensity of the magnetic field produced by the magnets and, consequently, the intensity of the heating produced by the eddy currents induced in the metallic product 3 to be heated.
  • the poles 4 have a circular section (this shape corresponds to a maximum magnetic flux for a given length of conductor and therefore for given Joule losses in the case of wound poles).
  • At least one of the inductors 1 and 2 is rotated about the vertical axis z by known means not shown in Figure 1, the other inductor can be rotated synchronously either by the same means of drive, or by the magnetic field produced by the first inductor.
  • the speed of rotation of the inductors 1 and 2 is usually significantly greater than the speed of advance of the metal product 3.
  • the pole surfaces of the poles 4 which are located opposite the large faces of the metal product 3 scan an annular zone 5 as shown in FIG. 2. This zone 5 roughly corresponds to the zone of action of the inductors on the metal product 3 to be heated.
  • the width of the metal product 3 to be heated does not allow homogeneous heating to be obtained over the entire width of the product 3 while it is advancing.
  • a heating device the dimensions of which are such that the outside diameter of its annular action zone 5 is significantly greater than the maximum width of the metallic products. 3 to be heated, so as to operate in the middle part of the heating profile C. It is therefore necessary to use heating devices which are large in relation to the width of the metal products 3 to be heated. Under these conditions, it will be noted that the magnetic flux produced by the inductors is not fully used for heating, since it does not act on the metal product 3 to be heated when, during their rotation, the magnetic poles are found beyond the longitudinal sides of product 3, hence a lower yield.
  • the present invention makes it possible to remedy this by providing a heating device having dimensions such that the diameter of its area of action is only very slightly greater than the maximum width of the moving metal products to be heated, and making it possible to heat the said areas. substantially homogeneously produced over their entire width with good yield.
  • this result can be obtained by using one or two inductors arranged like those of FIG. 1, but whose magnetic poles, constituted for example by electromagnets, have polar surfaces in the shape of a curvilinear triangle.
  • FIG. 3 shows by way of example, in front view, an inductor according to the present invention comprising four magnetic poles 4 of identical shapes and of alternating polarities.
  • Each magnetic pole 4 may comprise a magnetic core 6, for example of circular cross section, around which is arranged an excitation winding (not shown) supplied with direct current.
  • Each core 6 is provided with a pole shoe or pole piece 7 which is an integral part of the core 6 or which is fixed to the end of the core which is adjacent to the metal product to be heated.
  • Each pole shoe 7 has a flat pole surface parallel to one of the large faces of the metal product to be heated.
  • each bloom 7 has the shape of a curvilinear triangle which has a vertex 8 directed towards the axis of rotation z of the inductor, two concave sides 9 and 10, which are symmetrical with respect to a straight line passing through the apex 8 and perpendicular to the z axis, and a convex side 11 in an arc of a circle centered on the z axis and whose radius of curvature is substantially equal to the outside radius R of the annular zone 6 swept by the polar surfaces.
  • equation (1) The solution of equations (5) and (6) is provided by equation (1). Indeed, taking into account equations (1) and (3), equation (5) can be written: from where: from where: which gives E m independent of d.
  • the variation in the time of the magnetic field B seen by the point P, of polar coordinates r, a (figures 3 and 5) during the rotation of the inductor can be represented by a succession of slots alternately positive and negative as shown in the figure 6.
  • Each slot corresponds to the passage of a pole 4 in front of the point P and has a width which corresponds to the length of the polar arc 8 (figure 3) of each pole 4 at the distance r at which the point P is located
  • This waveform of the magnetic field B seen by the point P can be decompensated in Fournier series and expressed by the relation:
  • Equation (11) Equation (11) then becomes: which can still be written: with:
  • each of the pole shoes 7 the shape of a curvilinear triangle whose concave sides 9 and 10 are arcs of a circle having a profile which approaches the determined ideal profile. as described above, and the convex side 11 of which is an arc of a circle having a radius of curvature substantially equal to the outside radius of the annular zone swept by the poles 4, this outside radius itself being slightly larger than the half the maximum width of metal products to be heated.
  • each polar surface in the shape of a curvilinear triangle is preferably symmetrical with respect to the straight line passing through its apex 8 and through the center O of the rotating inductor, in order to obtain better balancing of the rotating masses.
  • the apex 8 of each curvilinear triangle is preferably truncated to avoid the leakage of magnetic flux between the poles 4 of opposite polarities.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Induction Heating (AREA)
EP82401998A 1981-11-13 1982-10-28 Dispositif de chauffage par induction magnétique de produits métalliques rectangulaires plats défilant dans le sens de leur longueur Expired EP0081400B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8121238 1981-11-13
FR8121238A FR2516641A1 (fr) 1981-11-13 1981-11-13 Dispositif de chauffage par induction magnetique de produits metalliques rectangulaires plats defilant dans le sens de leur longueur

Publications (2)

Publication Number Publication Date
EP0081400A1 EP0081400A1 (fr) 1983-06-15
EP0081400B1 true EP0081400B1 (fr) 1986-08-27

Family

ID=9263961

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82401998A Expired EP0081400B1 (fr) 1981-11-13 1982-10-28 Dispositif de chauffage par induction magnétique de produits métalliques rectangulaires plats défilant dans le sens de leur longueur

Country Status (5)

Country Link
US (1) US4481397A (ja)
EP (1) EP0081400B1 (ja)
JP (1) JPS5894789A (ja)
DE (1) DE3272924D1 (ja)
FR (1) FR2516641A1 (ja)

Families Citing this family (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL8304240A (nl) * 1983-12-08 1985-07-01 Skf Ind Trading & Dev Wiellager.
US4761527A (en) * 1985-10-04 1988-08-02 Mohr Glenn R Magnetic flux induction heating
US4856097A (en) * 1988-03-29 1989-08-08 Glenn Mohr Apparatus for induction heating of electrically conductive metal wire and strip
US5529703A (en) * 1990-06-04 1996-06-25 Nordson Corporation Induction dryer and magnetic separator
US5483042A (en) * 1990-06-04 1996-01-09 Nordson Corporation Magnetic separator
US5847370A (en) * 1990-06-04 1998-12-08 Nordson Corporation Can coating and curing system having focused induction heater using thin lamination cores
WO1992009397A1 (en) 1990-11-30 1992-06-11 Heron Technologies, Inc. Induction dryer and magnetic separator
WO1993023970A1 (en) * 1992-05-08 1993-11-25 Heron Technologies, Inc. Induction dryer and magnetic separator
CA2185438C (en) * 1994-03-16 2004-02-10 Robert Lloyd Apparatus for eddy current heating, heat storage, electricity generation, and lens moulding process
FR2733553B1 (fr) * 1995-04-25 1997-07-11 Pem Sa Protection Electrolytiq Dispositif de contre-collage pour la solidarisation d'une bande metallique et d'une bande de materiau isolant
DE102008014165A1 (de) * 2008-03-14 2009-09-24 Ab Skf Vorrichtung zum Erwärmen und Verfahren zum Erwärmen
WO2009126850A1 (en) * 2008-04-11 2009-10-15 The Timken Company Inductive heating using permanent magnets for hardening of gear teeth and components alike
US8993942B2 (en) 2010-10-11 2015-03-31 The Timken Company Apparatus for induction hardening
EP3199647B1 (en) * 2010-10-11 2019-07-31 The Timken Company Apparatus for induction hardening

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR916287A (fr) * 1944-04-01 1946-12-02 Brown Procédé et dispositif pour le chauffage électrique de pièces métalliques
CH264034A (de) * 1947-10-28 1949-09-30 Bbc Brown Boveri & Cie Verfahren zum induktiven Erhitzen metallischer, plattenförmiger Werkstücke.
GB1036725A (en) * 1962-05-05 1966-07-20 Delapena & Sons Ltd Improvements in or relating to induction heating
CH416879A (de) * 1963-04-01 1966-07-15 Baermann Max Ofen zur Erwärmung von metallischen Teilen
FR1387653A (fr) * 1964-03-31 1965-01-29 Four pour le chauffage de pièces métalliques
FR2473244A1 (fr) * 1980-01-04 1981-07-10 Cem Comp Electro Mec Procede et dispositif de chauffage electrique par induction de produits metalliques, utilisant des champs magnetiques pulses

Also Published As

Publication number Publication date
EP0081400A1 (fr) 1983-06-15
FR2516641B1 (ja) 1984-01-27
FR2516641A1 (fr) 1983-05-20
JPS5894789A (ja) 1983-06-06
DE3272924D1 (en) 1986-10-02
US4481397A (en) 1984-11-06
JPS623554B2 (ja) 1987-01-26

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