Heating device and corresponding apparatus and method

Abstract

A heating device and/or method to heat a slab, and in particular its edges, by electromagnetic induction, including an electric coil and a magnetic concentrator associated with the electric coil.

Claims

1. A heating device to heat a slab, having edges, by electromagnetic induction comprising: an electric coil defined around a winding axis and having at least two longitudinal tracts extending in a longitudinal direction, beyond the width of the slab to be heated, orthogonal to said winding axis and perpendicular to a direction of feed along which the slab is made to advance, and at least two connection tracts connecting and substantially orthogonal to said longitudinal tracts, said connection tracts being in use external to the edges of said slab to be heated, a magnetic concentrator positioned adjacent said electric coil and configured to transfer the power generated by said electric coil to said slab, said magnetic concentrator comprising two lateral portions connected to each other by a connection portion, said connection portion comprising a plate with a plane development located orthogonal to the winding axis and facing toward the electric coil and extending along the entire length of the longitudinal tracts, wherein said magnetic concentrator comprises at least a wall located outside a respective connection tract of said electric coil and facing toward the electric coil for substantially enclosing the electric coil, and further wherein the magnetic concentrator comprises a central body protruding along said winding axis, the central body located in said electric coil and extending in said longitudinal direction.

2. The heating device as in claim 1, wherein said magnetic concentrator further comprises at least one segment located outside a respective one of the longitudinal tracts and facing toward the said respective longitudinal tract.

3. The heating device as in claim 2, wherein said magnetic concentrator comprises two segments located at the side of said wall.

4. The heating device as in claim 2, wherein said wall and/or said segment extend parallel to said winding axis, to cover said connection tracts and at least part of said longitudinal tracts.

5. The heating device as in claim 2, wherein said magnetic concentrator comprises a covering wall located outside said electric coil, facing toward the electric coil and connected at least to said wall.

6. An electromagnetic induction heating apparatus for a slab, comprising at least two heating devices as in claim 1, located on respective lying planes substantially parallel and with respective electric coils facing each other to define an intermediate space for the transit of said slab.

7. An apparatus as in claim 6, wherein said electric coils of each heating device are connected to respective electric power sources, and wherein the apparatus further comprises a control unit connected to said electric power sources to command the autonomous functioning of each heating device.

8. A method to heat a slab by means of a heating apparatus as in claim 6, which provides to concentrate the magnetic induction generated by said connection tracts of each electric coil by means of the respective walls and/or segments of a magnetic concentrator associated therewith and toward the corresponding central body and/or plate in order to reinforce the power transferred from said electric coils to said slab.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other characteristics of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

(2) FIG. 1 is a perspective view of a heating apparatus according to one of the embodiments of the present invention;

(3) FIG. 2 is an exploded view of a heating apparatus according to one of the embodiments of the present invention;

(4) FIG. 3 is a section view of FIG. 1;

(5) FIG. 4 is a section view along the line IV-IV;

(6) FIGS. 5-9 are perspective views of possible heating devices according to five embodiments of the present invention;

(7) FIGS. 10-12 show three possible embodiments of a detail of a heating device according to the present invention.

(8) To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can conveniently be incorporated into other embodiments without further clarifications.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

(9) Embodiments described here, with reference to the drawings, concern a heating device 20 for heating a slab 21 by electromagnetic induction.

(10) In order to simplify the description, we will refer to a slab 21, this term comprising slabs, strip, plate or other flat metal products, in which there are edges 22 and/or corners 23.

(11) According to the invention, the heating device 20 comprises an electric coil 24 defined around a winding axis Z and having at least two longitudinal tracts 25 extending in a longitudinal direction X, orthogonal to the winding axis Z (see FIG. 6), and at least two transversal connection tracts 26 connecting longitudinal tracts 25. The connection tracts 26 of the electric coil 24 are disposed, in use, externally to the respective edges 22 of the slab 21 to be heated.

(12) Here and hereafter in the description, it is intended that the slab 21 is made to advance in a direction of feed Y substantially perpendicular to the longitudinal direction X.

(13) According to possible embodiments, the electric coil 24 can consist of an electric cable having a square, circular or polygonal section, which is wound around the winding axis Z to obtain a plurality of spirals.

(14) Each electric cable can have a transverse bulk comprised between 10 mm and 50 mm.

(15) In the case of an electric cable with a square cross section, the side of the square that defines the cross section can be comprised between 10 mm and 50 mm.

(16) Advantageously, the side of the square can be equal to about 30 mm, while in the case of an electric cable with a circular cross section its diameter can be equal to about 30 mm.

(17) According to advantageous solutions of the present invention, the sizes of the transverse bulk of the electric coil 24 can be comprised between 25 mm and 300 mm, advantageously equal to about 115 mm.

(18) Advantageously, in the case of an electric coil 24 having a transverse bulk with a quadrilateral shape, the ratio between the transverse sides that define the quadrilateral can be comprised between 0.15 and 6.7.

(19) According to advantageous solutions, considering a defined width of the slab 21, the longitudinal tracts 25 can have a longitudinal extension comprised between 1.1 times and 6 times the width of the slab 21.

(20) Even more advantageously, the longitudinal tracts 25 can have a longitudinal extension comprised between 2 and 5 times the width of the slab 21.

(21) For example, the slab 21 has a width comprised between 600 mm and 4000 mm.

(22) According to possible embodiments, the electric coil 24 can be made of a conductive material, for example a material having a high electro-conductivity, such as copper.

(23) According to possible embodiments, the electric cable that constitutes the electric coil 24 can be cooled by a cooling liquid made to transit in contact with it.

(24) In order to slow down the deterioration of the electric cable, the latter can be located inside respective cooling ducts where a cooling liquid passes, such as for example water, oil, or other temperature conducting fluid.

(25) The heating device 20 also comprises a magnetic concentrator 27 associated with the electric coil 24 and provided with at least two lateral portions 28 connected to each other by means of a connection portion 29.

(26) By the term “connected”, we mean that the lateral portions 28 are connected to each other in continuity with the connection portion 29, and also that the lateral portions 28 are connected to each other in continuity with the connection portion 29, that is, the magnetic flow lines can circulate between them even in the presence of a minimum gap.

(27) The magnetic concentrator 27 and its components can comprise a plurality of magnetic metal foils, overlapping and clamped to each other to form a single body, or an assembly consisting of a plurality of magnetic sectors, in a known manner.

(28) The magnetic foils can be made of ferromagnetic material such as for example iron, nickel, cobalt, their alloys or other suitable materials.

(29) The magnetic concentrator 27 can be made completely, or partly, of one or more magneto-dielectric compact materials, which are not in laminated form.

(30) For example, a magneto-dielectric compact material can comprise ferromagnetic metal powders incorporated in an insulating matrix.

(31) The lateral portions 28 can be connected to the connection portion 29 in a removable manner. This simplifies assembly and/or maintenance operations.

(32) In accordance with one aspect of the present invention, each of the lateral portions 28 comprises a wall 30.

(33) Each wall 30 of the magnetic concentrator 27 is located outside of a respective connection tract 26 of the electric coil 24 and facing toward the latter, as can be seen in FIG. 8, substantially enclosing from the outside the connection tract 26.

(34) According to possible embodiments, the wall 30 is located orthogonal to the longitudinal direction X.

(35) According to possible embodiments, the wall 30 has a shape mating with the peripheral profile of the connection tract 26.

(36) According to possible embodiments, each of the lateral portions 28 of the concentrator 27 can comprise at least one segment 31 located outside a respective longitudinal tract and facing toward the latter.

(37) According to possible embodiments, the segment or segments 31 are connected to the wall 30.

(38) The segments 31 are located outside the respective longitudinal tracts 25 and facing toward the latter.

(39) According to possible embodiments, the magnetic concentrator 27 comprises two segments 31 located at the side of the wall 30. For example, four segments 31 can be provided, located two by two at the side of a respective wall 30.

(40) The lateral portions 28, or the walls 30 and/or the segment and/or segments 31, extend parallel to the winding axis Z to cover and close from the outside the connection tracts 26 and at least part of the longitudinal tracts 25 of the coil 24.

(41) According to possible solutions, the lateral portions 28 extend in an inclined direction to the winding axis Z to cover and close from the outside the connection tracts 26 and at least part of the longitudinal tracts 25.

(42) According to possible embodiments, the wall 30 covers the extension, that is, the thickness, of the connection tracts 26 and of the longitudinal tracts 25 in directions parallel to the winding axis Z.

(43) The lateral portions 28 of the concentrator 27 allow to use the power generated by the connection tracts 26 of the electric coil 24, which is added to the contribution generated by the longitudinal tracts 25, thus making the overall transfer of power to the slab 21 more efficient, and in particular to its edges 22 and in proximity to them.

(44) Thanks to the reinforcement of the magnetic induction due to the conformation of the lateral portions 28 connected to each other by means of the connection portion 29, it is possible to heat the edges 22 of the slab 21 efficiently, since the power transferred to the latter is increased by the contribution of the connection tracts 26.

(45) In contrast to the prior art, thanks to the provision of the external walls 30 of the concentrator 27, the power generated by the connection tracts 26 is not dispersed in directions not intended for heating the slab 21, but is concentrated towards the connection portion 29 which transfers it to the slab 21.

(46) In accordance with possible solutions, the lateral portions 28 can comprise a covering wall 32 located outside the electric coil 24 and facing toward the latter.

(47) The covering wall 32 can be connected at least to the wall 30 and possibly to the segments 31.

(48) The covering wall 32 is configured to cover at least part of the electric coil 24 on a plane perpendicular to the winding axis Z and in proximity to the wall 30.

(49) The presence of the covering walls 32 associated with the connection tracts 26 and with part of the longitudinal tracts 25 allows to transfer the power generated by the portions covered by the covering wall 32 to the slab 21.

(50) Consequently, in this case, part of the electric coil 24 is left uncovered by the lateral portions 28, said part left uncovered facing the slab 21 during use.

(51) According to possible embodiments, the connection portion 29 comprises a central body 33 protruding along the winding axis Z.

(52) The central body 33 is located in the electric coil 24 and extends along the longitudinal direction X.

(53) Between the central body 33 and the walls 30 of the lateral portions 28 two passage spaces can be provided for the electric coil 24, in particular for the connection tracts 29.

(54) The central body 33 allows to transfer, during use, the power generated by the longitudinal tracts 25 to the slab 21 while it is passing in the direction of feed Y.

(55) According to possible embodiments, the connection portion 29 comprises a plate 34 with a plane development located orthogonal to the winding axis Z and facing toward the electric coil 24.

(56) According to possible solutions, the segments 31 extend along the entire length of the longitudinal tracts 25.

(57) The presence of the plate 34 and/or the segments 31 extending along the entire length of the longitudinal tracts 25 allows to concentrate the power generated by the latter and not to disperse energy in directions not intended for heating the slab 21.

(58) Advantageously, the presence of the walls 30 extending along the entire length of the connection tracts 26, that is, which entirely cover the latter, allows to concentrate the power generated by them and not to disperse energy in directions not intended for heating the slab 21.

(59) It should be noted that the magnetic concentrator 27 can advantageously be made in a single body. In particular, the wall 30 and/or the segments 31 and/or the covering wall 32 and/or the central body 33 and/or the plate 34 can be made in a single body.

(60) According to possible embodiments, the wall 30 and/or the segments 31 are connected to the central body 33 and/or to the plate 34 in a removable manner.

(61) In accordance with possible embodiments, the electric coil 24 is provided with at least two supply terminals 35 exiting from at least one of the lateral portions 28 and configured to electrically connect the electric coil 24 to an electric power source 36.

(62) The electric power source 36 can be associated with adjustment devices to vary the intensity of the electric current, the electric voltage, and the supply frequency.

(63) FIG. 4 illustrates the path of the electric current in the electric coil 24 with a continuous arrow and the path of the electric current induced in the slab 21 with a dotted line.

(64) According to possible embodiments, at least one of the lateral portions 28 comprises at least one aperture 37, in which at least one of the supply terminals 35 is located.

(65) In accordance with possible solutions, shown in FIG. 1, the present invention also concerns a heating apparatus 38 for a slab 21 by electromagnetic induction.

(66) The heating apparatus 38 comprises at least two heating devices 20 as in any one of the embodiments described above, located on two substantially parallel lying planes and with the respective electric coils 24 facing each other and between which there is an intermediate space 39 for the transit of the slab 21.

(67) According to possible embodiments, not shown, the space 39 can be varied by modifying the reciprocal position of the two heating devices 20.

(68) In accordance with possible solutions, the electric coils 24 are connected to respective electric power sources 36 configured to autonomously condition the polarity of each of the components of the magnetic concentrator 27.

(69) According to possible embodiments, the electric coils 24 of each heating device 20 are connected to respective electric power sources 36 to command the autonomous functioning of each heating device 20.

(70) This conditioning is actuated by modifying the direction of travel of the electric current through the electric coil 24.

(71) In FIG. 3, the electric coils 24 are characterized by the direction of the electric current: “+” indicates an incoming electric current and “•” indicates an outgoing electric current.

(72) According to possible solutions, the heating apparatus 24 can comprise electromagnetic screens 40 configured to screen other bodies and/or elements located near the heating element 24 from the magnetic field generated by the magnetic concentrators 27.

(73) The electromagnetic screens 40 can be located at the side of the magnetic concentrators 27 and parallel to the longitudinal tracts 25.

(74) The heating apparatus 38 exploits the presence of the lateral portions 28 to heat mainly the edges 22 of the slab 21, also transmitting part of the power in the central zone of the slab 21 itself.

(75) According to possible embodiments, the heating apparatus 38 can be installed before a rolling train, for example before the roughing or finishing stand.

(76) This allows to improve the heat profile of the slab 21 and also to bring the temperature of the edges 22 to a desired value, so as to compensate for the further heat dissipation of the edges 22 during the passage of the slab 21 in the heating apparatus 38.

(77) According to further solutions, the present invention also concerns a method for heating slabs 21 which provides to concentrate the magnetic induction generated by the connection portions 26 of each electric coil 24 by means of the respective lateral portions 28, that is, the respective walls 30 and/or segments 31 associated therewith, and toward the corresponding connection portion 29, that is, the central body 33 and/or the plate 34, so as to reinforce the power transferred from the coils to the slab 21, particularly to the edges 22 of the latter.

(78) It is clear that modifications and/or additions of parts can be made to the heating device 20, the heating apparatus 38 and the heating method as described heretofore, without departing from the field and scope of the present invention.

(79) It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of heating device 20, the heating apparatus 38 and the heating method, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.