MXPA96003973A - Assembly of induction heating coil for the prevention of circulation currents in induction heating lines for products of foundry conti - Google Patents

Abstract

The present invention relates to an induction heating coil assembly for use in a roller induction heating line having a magnetic shunt for receiving a portion of an electromagnetic field generated along the axis of the induction coil and directing that portion along a path parallel to a workpiece that passes along the heating line, this magnetic flux path ensures that eddy currents induced in the workpiece flow primarily perpendicular to the axis of the workpiece. piece of work, and not along the axis of the workpiece where it could cause arcing between the moving workpiece and the conveyor rollers

Description

ASSEMBLY OF INDUCTION HEATING COIL FOR I. fl PREVENTION OF CIRCULATION CURRENTS IN INDUCTION HEATING LINES FOR FOUNDRY PRODUCTS KEEP GOING FIELD OF THE INVENTION The present invention relates to the heating or the production of continuous smelting products such as slabs, ingots, rods and the like.

BACKGROUND PE LR INVENTION It is often desired to heat continuous casting products (eg, slabs, ingots, or other work pieces) when transported from one place to another along a route. Typically, such products are transported with conveyor rollers that hold the product from below and are driven to impart linear movement to the product. In Figure 1, a typical line of induction heating of roller 10 for continuous cast products, according to the prior art, is schematically illustrated. A continuous casting product t-a as a tubular workpiece 12 is transported from right to left, as seen in FIG. 1, by steel conveyor rollers 14 and 15. The transport rollers 14 and 16 are run through for rotation in a support structure and rotationally actuated in a known manner in a direction lev rotates, as shown in figure 1. The rotating ion of the rollers t ansporters 14 and 16 impart linear movement of the tubular workpiece 12 of right to left, as indicated by the large arrow at the top of figure 1. As the tubular workpiece 12 is transported by the conveyor rollers 14 and 16, it passes through an induction heating coil 18. Induction heating coil 18 is a conventional helically wound coil known in the art. The induction heating coil 18 is energized by a high frequency ac energy source 20, also known in the art, and generates an electromnatic field through which the tubular workpiece 12 passes. Typically, the workpiece tubular 12 is positioned so that its ee is coJmeal with the axis of the coil 18. The electromagnetic field produced by the induction coil 18 induces the flow of currents for the tubular workpiece 12. The electrical resistance of the the workpiece 12 to the induced torque currents results in heating r ^ of the tubular workpiece 12. However, problems arise because the induction coil 18 generates a small, but not negligible, component of the electromagnetic field ico perpendicular to the axis of the coil and, thus, along the axis of the tubular workpiece 12. This electromagnetic field component produces an electric current flowing to the length < The axis of the tubular workpiece 12, represented by the small horizontal arrows pointing to the right in FIG. 1. This current, known as a running current, starts to circulate along a path from the workpiece. of tubular work 12 and inside the conveyor rollers 14 and 16 through a common ground, such as the support structure in which the rollers are traversed. This route is represented by the curved arrow shown below the conveyor rollers in Figure 1 (although the figure illustrates a parasitic current flow in one direction, it will be understood that the parasitic current is an alternating current since the coil is energized by a source of energy ac). This phenomenon causes arcing between the moving tubular workpiece 12 and the feeder rollers 14 and 16, which causes corrosion and other damage to the conveyor rollers. Prior to the present invention, the most common way to avoid the flow of eddy currents was to isolate the transport rollers from the ground, to break the current path. This involves uncomfortable and expensive steps. One approach was to make the ceramic conveyor rollers. Ceramic transport rollers are very expensive and can easily break. Other techniques included the construction of concentric steel interior conveyor rollers and outer tubes insulated from each other by an intermediate insulator, such as a cerica. Such rollers are extremely expensive to manufacture and are subject to failure due to the differential expansion and contraction between the steel and the insulating material when the rollers are subjected to the high temperatures that are used in the heating operation. with inuo. In some cases, no attempt is made to eliminate parasitic currents. It allows the streams to flow, and the conveyor rollers are periodically removed from the line and re-smoothed to eliminate corrosion. Obviously, none of these approaches is very satisfactory. The present invention provides a way to prevent the flow of parasitic currents. Accordingly, the present invention avoids damage to the conveyor rollers that causes stray current, and eliminates the need for special conveyor rollers and insulating models to block flow in eddy currents. The present invention makes roller induction heating easier and cheaper than previous approaches.

BRIEF DESCRIPTION OF THE INVENTION The present invention is directed to an induction heating coil assembly for use in a heating induction roller line. The induction heating line comprises conveyor rollers for transporting a workpiece (for example a slab) to be inductively heated along a linear path and a heating induction coil assembly 5 which surrounds the route. The crank induction coil assembly has a central axis and comprises an induction coil and a magnetic shunt that surrounds the coil. The induction coil has a multitude of turns and is configured to define a preselected perimeter for Lf) allow the work piece to be received within the perimeter. The magnetic bypass includes first and second plurality of transverse forks at opposite ends of the coil, and a plurality of intermediate forks spaced apart from each other. The intermediate forks are arranged between the first and second plurality of forks and extends parallel to the axis of the coil. The intermediate forks extend around the perimeter defined by the induction coil. The first and second plurality of forks are axially spaced apart and electromagnetically coupled to one another by the plurality of intermediate forks. A second embodiment of the invention allows the heating induction apparatus to be placed around a work piece of strip material that is already in place on a conveyor. This embodiment comprises one or more full turn coils connected between They do have space at one end. The space allows the apparatus to move on a strip work piece so that the work piece passes between the open ends of the full turn coils and is encircled by the apparatus. This embodiment further comprises a plurality of magnetic forks disposed along elongated induction segments comprising the turns of the coil. The forks extend along induction segments at a distance at least equal to the width of the strip workpiece and are arranged parallel to the longitudinal axis of the workpiece. A magnetic field reducer is located at the end of the apparatus space and the magnetic branch is disposed at the opposite end of the apparatus. During operation, the plurality of forks functions as a magnetic shunt to direct the electromagnetic field generated by the induction field along a path parallel to the axis of the coil, and thus parallel to the La a. This magnetic flux path induces torque currents in the workpiece. However, due to the orientation of the forks, there is no appreciable orthogonal component to the flow of the magnetic field (that is, there is no appreciable perpendicular component to the axis of the coil or workpiece). Therefore, the eddy currents induced in the workpiece flow perpendicularly to the axis of the workpiece. No appreciable induced eddy current flows along the workpiece or below it. According to ost, no harmful partners are cited through the rollers and the responders. DESCRIPTION OF THE DRAWINGS For the purpose of illustrating the invention, a form which is currently preferred is shown in the drawings; it should be understood, however, that this invention is not limited to the precise provisions and structures shown. Figure 1 is a schematic representation of an induction heating coil in relation to a workpiece to be heated, in accordance with the prior art. FIGS. 2A and 2B are identical perspective views of the novel induction heating coil assembly in relation to a work pipe that is to be enclosed. Figure 3 is a perspective view of the novel induction heating coil assembly, with a portion of the magnetic derivation removed to show the induction coil in it. Figure 4 is an end view taken along line 4-4 in Figure 2A. Figure 5 is a cross-sectional view taken through line 5-5 in Figure fi. Fig. 6 is a longitudinal sectional view taken through line 6-6 in Fig. A. Figs. 7 and 8 are longitudinal section views taken through line 6-6 of an alternative embodiment of the Figure 2A. Figure 9 is a partial sectional view of a coil assembly according to the invention in greater detail, showing insulating layers between the magnetic branches and the turns of the coil. Figure 1 (1) is an exploded view of a coil assembly according to the invention, showing optional magnetic bypass endplates.Figure 11 is a sectional view of the second described embodiment of the invention, as along the line BB in Figure 14. Figure 12 is a simplified linear diagram of the configuration of the underlying coil structure of the second described embodiment of the invention, Figure 1 is a sectional view of the second. described embodiment of the invention taken along the line CC in figure 14. Figure 14 is a top plan view of the second described embodiment of the invention, Figure 15 is a perspective view of the second described embodiment of The invention Figure 16 is a perspective view of a third embodiment of the invention.

DESCRIPTION OF THE INVENTION Although the invention will be described in connection with one or more preferred embodiments, it is understood that it is not intended to limit the invention to the embodiments described. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included in the spirit and scope of the invention as defined by the appended claims. Referring now to the drawings, FIG. 2A shows a perspective view of a roller induction heating line 2? and the novel induction heating coil assembly 24 associated therewith. Figure 3 shows a perspective view of the novel induction heating coil assembly. For clarity, Figures 2A and 3 are described together. The line 22 t yields a continuous casting workpiece such as a slab 26. Along it, the line 22 can also carry work pieces that have other shapes, such as the tubular work piece 12 shown in FIG. Figure 1 of the prior art. As seen in FIG. 2A, the slab 26 is transported from right to left lmeally by steel conveyor rollers 27 and 29. These rollers operate in the same way as described above in relation to the previous technique in FIG. The induction heating coil assembly 24 surrounds the slab 26 so that the slab 26 passes through the assembly of the coil 24. The assembly 24 includes the induction heating coil 28 and a magnetic shunt 30 surrounding the ends 31 and the outer perimeter P0 of the induction heating coil 28. The induction heating coil 28 is a conventional coiled winding coil that operates in the same manner as the coil 18 described in Figure 1 of the prior art. The induction heating coil 28 has a central axis A and a length lc. The slab 26 thus passes through an area defined by the inner perimeter of the coil Pi and the length lc. The coil 28 is preferably positioned with respect to the a 26 so that the longitudinal axis of the slab B is collinear with the central axis of the induction coil A. It is illustrated that the magnetic shunt 30 has 3 distinct portions. The first portion comprises a first plurality 32 of individual transverse forks 34 and the second portion comprises a second plurality 36 of individual transverse forks 38. A third portion comprises a third plurality 40 of individual intermediate forks 42. However, if desired, the Transverse forks and intermediate forks can be a single unit, or be joined together to form a single unit. Each plurality of individual transverse forks 34, 30 are separated from each other by nonconducting spacers configured identically 44; in a stacked or interleaved form. Each plurality of individual intermediate forks 42 is also spaced apart from each other by non-conductive spacers configured identically 46 in a similar stacked manner. A non-conductive spacer material-suitable for both types of forks is Myl rR. As described in more detail below, the plurality of individual transverse forks 34, 38 extend completely around all of the end areas 31, of the induction coil 28, while the intermediate forks 42 are arranged in a plurality of groups. , each group separated by a relatively small air space. These air spaces create small discontinuities along the outer perimeter P of the assembly 24. The specific arrangement of the forks is an important feature of the invention. The first and second plurality of individual transverse forks 34, 38 are oriented transversely to the outer perimeter P0 of the induction coil 28, and are disposed at opposite ends of the coil. Each of the individual transverse forks 34 and 38 is defined by a flat front end 48 and a flat front end 50.

The transverse forks 14 and 38 are placed at opposite ends 31 of the induction coil 28 so that the forks extend axially inwardly, slightly passing the inner perimeter P of the induction shaft coil 28. The non-conductive spacers 44 are oriented in the same manner as the transverse forks 34 and 38. The transverse forks 34, 38 and the spacers 44 extend completely around the ends of the perimeter of the induction coil 28, but do not touch them. In the embodiment shown, the forks 4, 38 extend around the perimeter generally in the form of a flattened oval. The transverse length lt of the forks 34 and 38 and the spacers 44 are the same along the entire perimeter, and the inner and outer front planar ends 48, 50 of the transverse forks 34 and 38 terminate respectively in common radial planes, as is also illustrated in Figure 4. To accommodate the corners of the oval configuration, the cross-hairpins 34, 38 and the spacers 44 along the corners are cuneiform. The individual intermediate forks 42 are disposed between the transverse forks 34, 38 and extend parallel to the central ee A of the induction coil 28. In this way, the intermediate forks 42 appear with radial fins extending from the induction coil 28. Each intermediate yoke 42 has a length "", which is slightly larger than the length 1 c of the tie coil 28. The plurality of intermediate forks 42 closely surrounds the outer perimeter P0 of the induction coil 28, but he does not touch it. Each of the intermediate forks 42 is defined by a flat front end 52 and a flat front end 54. The flat outer ends 54 of the hordes Intermediate 42 terminate in the same radial common oval shape that the flat ends of the outer face 50 of the transverse forks 34 and 38. Again, the non-conductive spacers 46 are oriented in the same manner as the intermediate forks 42. the transverse forks 34 and 38 extend around the entire perimeter of the frames. respective ends of the induction coil 28, while the intermediate forks are arranged in spaced groups, separated by small air spaces 56. In the embodiment described herein, there are 16 such groups, as best illustrated in FIG. figure 5. The first and second plurality of individual transverse forks 34, 38 are electromagnetically coupled to each other by intermediate forks respective 42 that rest on the same plane or is rejectably adjacent to it. For example, in FIG. 3, the transverse forks 34 and 30-L are coupled in between by the intermediate forks 42a .. This electromagnetic coupling allows the L4 flow magnetic flow easily along the length of the magnetic branch 30. Due to the air spaces 56, not all of the transverse forks 34, 38 are electromagnetically coupled to each other by a respective intermediate fork 42 in the same plane. This pair of transverse forks 34, 38 are electromagnetically coupled by means of adjacent intermediate forks 42. Since the air spaces 56 are relatively small compared to the length of the entire magnetic flux path, there is a small but relatively small divergence. importance in the magnetic flux path at each end. Figure 2B is identical to Figure 2A and illustrates the functional advantage of the induction heating coil assembly 24 during the operation of the roll induction heating line 22. When power is applied to the induction coil 28 (not visible in this view), the induction coil 28 generates an electromagnetic field having components along a path both parallel and perpendicular to the central axis A (not shown) of the induction coil 28. The perpendicular component is very small compared to the parallel component, but it is, nevertheless, large enough to be problematic if it is not eliminated. The plurality of forks in the magnetic branch 30 directs both components of the electromagnetic field along a path parallel to the center axis A of the induction coil 28, and thus parallel to the longitudinal axis B of the slab 26. The magnetic flux induces eddy currents in the a 26 .. Since the transverse forks 34, 38 and the intermediate forks 42 are oriented parallel to the longitudinal ee B of the slab 26, substantially all the magnetic flux is directed to the along this route. This route is shown in Figure 2B as a series of continuous line arrows. There is no appreciable orthogonal component to the magnetic flux. That is, there is no appreciable perpendicular component to the longitudinal axis B of the slab 26. Therefore, the parasitic current induced in the slab 26 flows primarily perpendicular to the longitudinal ee of the slab B. This parasitic current is shown in the figure 2B as a dashed line arrow on the slab 26, and is best illustrated in FIG. 5. No appreciable induced torque currents flow along or under the longitudinal axis B of the a to 26. According to this, no harmful harmful parasites are circulated through the conveyor rollers 27 and 29. If the magnetic bypass 30 was not present, the electromagnetic field would extend in all directions at the ends of the induction coil 28, as shown by the arrows of lines imaginary dots, and could have a non-negligible orthogonal component. Therefore, non-negligible parasitic currents would be induced to flow in the slab 26 along the longitudinal axis of the slab B, causing the problems discussed above. " Figures 4, 5 and 6 show extreme and sectional views taken through Figure A, and more clearly illustrate certain characteristics of the invention. Figure 4 is an extreme view taken through line 4- 4 in Figure 2A. This view shows the arrangement of the first alternating plurality 32 of transverse nozzles 34 and non-conductive spacers 44 that completely surround the end of the induction coil 28. Since the forks 34 and the spacers 44 are interspersed or stacked together, the coil Induction 28 is not visible in this view. Figure 4 also clearly shows the uniform transverse forks (for example 34s) and the spacers (for example 44a) along the corners of the oval configuration. The slab 26 to be heated is disposed centrally within the surrounding transverse forks 34. Figure 5 is a cross-sectional view taken through line 5-5 in Figure 6. This view shows the 16 spaced apart groups of intermediate forks 42 and spacers 46, separated by small air spaces 56. A turn of induction coil 28 is also visible in this view. Figure 5 also shows the parasitic current induced as a dotted line arrow on the slab 26. Of course, the direction of this alternating current on the same frequency as the alternating current source used to excite the induction coil 28. The direction shown in Figure 5 is that of a given moment of time.

Figure 6 is a longitudinal sectional view taken through line 6-6 in Figure 2A. This view shows a portion of the magnetic bypass 30 made of two end-running end forks 34, 38 and an intermediate fork connecting thereto disposed in the longitudinal plane. the plurality of turns of the induction coil 28 are also visible in this view. Figure 6 also shows that the magnetic shunt 30 surrounds the ends and the outer perimeter P0 of the induction coil 28. As described above, the forks of the magnetic shunt 30 provide a magnetic flux path for the electromagnetic field component along the central axis A of the induction coil 28. The route through the forks 34, 42, 38 and the slab 26 is shown as a continuous line arrow .. Again, it should be understood that the direction of the alternate route on the same frequency as the used alternating current source that excites the 2fl induction coil. The direction shown in Figure 6 is that of a given moment of time. The magnetic shunts 30 can be constructed in a plurality of different shapes, as shown in Figs. 7 and 8. In Fig. 7, the transverse end forks 34, 38 are shorter in length and the intermediate yoke 42 is longer in each case. end to overlap the extreme forks 34 and 38. In figure 8, the transverse end forks 34, 38 and the intermediate fork 42 are formed with a continuous piece of material, the non-conductive spacers 44 and 46 can also be constructed in the same Alternate configurations than forks. The embodiment of the invention as illustrated and described is used to heat rectangular shaped loads or work pieces, such as tiles. However, the scope of the invention includes embodiments for heating other forms of loading, such as tubular or cylindrical workpieces. In these alternate modalities, coil 28 and magnetic shunt 30 would generally be circular, not oval in the transverse section. It will be appreciated that the assembly of the coil 24 is subjected to very large mechanical forces as a result of the magnetic interaction between the coil 28 and the workpiece. In a large installation, these forces could amount to several tons. Normally, in a typical cylindrical induction coil, these forces are equally distributed over the circumference of the coil, and therefore are in balance, or radial symmetry around the periphery of the coil. However, in this situation, where the coil is a flattened oval, the forces will not be symmetrical around the periphery of the coil and there will be net forces of substantial magnitude that result between the coil and the work piece. To assist in the reinforcement of the coil assembly 28, magnetic taps can be firmly secured against the windings of the coil, as shown in Figure 9. Figure 9 illustrates a plurality of clamps 58 on the intermediate forks 42 and on transverse end forks 38. Clamps 58 apply compressive forces on the coil turns. The compressive forces on the intermediate forks 42 are radial, as represented by the arrows FR .. and the compressive forces on the extreme forks 38 are axial, as represented by the arrows F ?. Clamps 58 may have any shape or structure designed to apply compressive forces to the forks and coil. To avoid electrical shorting between the turns of the coil, the forks are insulated from the coil turns by insulating spacers 60. The spacers 60 can be of any suitable non-conductive non-magnetic material. Although the arrangements of the shunts described above are highly effective in the direction of the magnetic flux produced by the coil 28It is possible to improve the performance even more by using electrically conductive magnetic flux deviation end plates, as shown in FIG. LO. Figure 10 is an exploded view of a coil assembly 24 including end plates 62 at each end of the coil assembly 24. The end plates 62 are generally rectangular in shape and have dimensions slightly larger than the overall dimensions of the exterior of the coil assembly. coil assembly 24. Each end plate 62 has a generally rectangular opening 64 at its center for adjusting the passage of a work piece through the opening. The opening 64 is approximately the same size and shape as the opening in the assembly of the coil 24 through which the workpiece passes. The end plates are preferably made of copper, which is a good conductor of electricity. and deviates the magnetic flux with minimal losses. The end plates 62 are located adjacent and axially outside the end forks 34 and 38. Preferably, the end plates are located a short distance from the end forks, and should not touch the outer fork. It is within the scope of the invention to place an insulating spacer between the end plates 62 and the end forks, if it is also desired to secure the end plates 62 against the end forks to further compress the induction coil 28. Even with the use of Assemblies with the shunts described above, stray magnetic flux from the coil assembly 24 can reach the rollers 14 and 16, particularly if the rollers are in close proximity to the ends of the coil assembly. parasitic currents flow in the rollers, and nullify the effect of the shunts .. The extrudate plates 62 direct any stray magnetic flux that could otherwise escape from the center of the opening of the coil assembly 24 to the extreme forks 34 and 38 and from there to the intermediate forks 42. In addition, the end plates 62 significantly improve the concentration of the magnetic flux inside the coil. The invention described above provides an alternative approach for preventing the flow of corrugating materials through a work piece, thereby eliminating arcing between the moving workpiece and the conveyor rollers. Since it is no longer necessary to employ special conveyor rollers or insulative models to prevent damage to the transport rollers of such currents, induction heating of rollers is made easier and cheaper than in the previous approaches. Another embodiment of the present invention adds flexibility to the way in which the invention can be employed on a strip material treatment line. In a rolled metal production line, it is for a continuous casting to produce metal strips, advancing the metal strip from a mold, cooled by water, supplied from a liquid metal supplier. The metal strip proceeds to a roller for further processing. When the metal strip emerges from the cast, the outer surface of the metal has been cooled by the mold cooled by water while the interior of the anger remains much hotter. Before rolling the new product into a freshly cast strip, it is necessary to reheat the exterior surface of the strip so that it is malleable during operation on the side. The ') - >; The induction heating is faster than the gas heating, since the coil of the present invention is a convenient apparatus with which the new metal can be heated. However, there are potential problems in the process of producing strip material that can put the first embodiment of the present invention at risk of damage. If the casting runs too fast, or the mold cooled by water does not cools the strip material evenly, a "whale" may develop on the new strip. A "whale" is a soft spot on the strip where the metal can remain semi-liquid. Gravity can cause the liquid portion to sink and form a metal bubble that could make contact with part of the coil apparatus described above, severely damaging it. The second embodiment of the present invention offers an alternative apparatus incorporating a similar magnetic fork and bypass arrangement allowing greater flexibility in the way in which the apparatus can be handled in the treatment line. The first described modality of the present invention is a coil completely wrapping the metal strip. To remove the strip from the coil, it is necessary to separate the material from the strip. The second mode described below is open at one end allowing the coil apparatus to be moved and removed from the strip material without interrupting the line. If a "whale" is found in the new metal strip, the coil is simply removed from the strip, the "whale" moves after the coil, then the coil output is returned to the strip and the line can continue- It is a much less labor-intensive effort to remove the bobbin from the strip than to remove the strip inside the bobbin. Therefore, the second embodiment of the invention comprises a winding-induction winding apparatus having magnetic suppression of orthogonal fields that can create a current flowing along the longitudinal axis of the workpiece. This second embodiment of the induction heating apparatus incorporates magnetic forks to confine the magnetic field so that the heating apparatus is moved and removed from the strip material in place. Referring to FIG. 12, this induction heating section 69 comprises a plurality of elongated induction segments 70, 72, 78, 80 arranged as a complement to the turns of the coil. The first and second induction segments 70, 72 are arranged parallel to each other and spaced sufficiently for a workpiece of strip material 100 to pass between them. The first and second induction segments 70, 72 are arranged transversely to the longitudinal axis A of the work piece LOO. At one end, the induction segments 70, 72 are connected to the first and second link segments 74, 76. The connections form substantially straight angles between the respective induction 70, 72 and the link segments 74, 76. That extr -emo of the first and second induction segments 70, 72 which is opposite the end connected by the connecting segments 74, 76 is connected to an alternating current power source 90, one pole of the power source being connected to each of the first and second segments 70, 72. The two induction segments of an on 74, 76 connect the first and second induction segments 70, 72 to the third and fourth induction segments 78, 80. the joining segments 74, 76 the induction segments 70, 72, 78, 80 are connected at substantial right angles so that the joint segments are parallel to the longitudinal axis a of a workpiece of strip material 100. The first and second joint segments 74 , 76 are d and equal length, shown as the dimension. in figure 12. The third and fourth induction segments 78, 80 are also arranged parallel to each other and spaced sufficiently for the strip material 100 to pass between them The third and fourth segments 78, 80 extend backward through the workpiece from the connection point to the connecting segments 74, 76. The third and fourth segments 78, 80 are connected to each other by a link segment 75 at its end opposite the end which is connected to the union segments. 2 n, As described, the induction heating apparatus 69 forms an inductive winding coil. There is a continuous driving path formed from a first pole of the power source 90, through the first induction segment 70, and first link segment 74, the third and fourth induction segments 78, 80, the second connecting segment 76 and back through the second induction segment 72 to the second pole of power source 90. The combination of the first and second induction segments 70.72 forms a complete revolution of the coil apparatus, the third and fourth Induction segment 78.80 forms a complete second revolution. Other embodiments of the invention described herein may be constructed having more than two complete turns without departing from the spirit and scope of the invention. For example, with reference to Figure 16, a third full turn can be added to the apparatus by adding two more link segments 102, 104 and two more elongated induction segments (not visible) spanning workpiece 100. Referring again to the 12, there is a space 82 between the two connecting segments 74, 76 at one end of the apparatus. The space 82, as the space between the first and second induction segments 70, 72 and the third and fourth induction segments 78, 30 is of sufficient dimension to allow the workpiece 100 to pass skewly in and out of the induction apparatus 69. In Figure 1 2 the dimension of the space 82 is indicated as 1 ^, which must be a dimension larger than the thickness of the metal strip to be heated. This allows the apparatus to be moved and removed from a slab strip or bar work piece. The subject of the embodiment of the invention has been described as if the constituent inductive segments and the link segments comprising the coil section were single solid conductors. Although this may be the case, as shown in Figures 15 and 16, it is not necessarily so. Referring to Figure 14, it can be seen that the pruner elongate induction segment 70 can comprise several individual lengths of conductive material 101, 104, 06, 108. Thus, the remaining junction segments and inducers can also comprise several individual conductors , as is the case in the preferred form of this embodiment of the invention. Referring to Figure 14, the coil apparatus further comprises magnetic forks 84 for the direction of the magnetic field that is aligned with the longitudinal axis of the workpiece. See also Figures 11 and 15. A plurality of magnetic forks 84 are disposed along the respective first to fourth elongate induction segments 70, 72, 78, 80. The plurality of magnetic forks 84 are disposed along the the elongated induction segments 70, 72, 78, 80 in a manner comparable to that described above for the intermediate forks 40 shown in Figure 2A. The individual magnetic forks are disposed transversally to the direction of flow of the current in the segment of the associated elongate induction, as shown in FIG. 13. The direction of current flow in FIG. 13 is indicated in the segments of induction 102, 104, 106, 108 by points (-) that indicate that current flows to the observer. A "+" indicates that the current flows away from the observer. Refer to FIG. 14, each of the magnetic forks 84 is spaced apart from each other by identically configured non-conductive spacers 87, the forks 84 and spacers 87 alternating in a stacked manner affer the elongate inductor segments 70, 72, 78, 80. The individual magnetic forks 84 are aligned parallel to the longitudinal ee A of the workpiece strip material 100 that passes through the coil apparatus. The magnetic forks 84 and the spacers 87 can be arranged in a plurality of groups, each group separated by a relatively small air gap, as shown in Figure 2 for the first described embodiment of the present invention. The plurality of magnetic forks 84 extends along each of the elongated inductor segments 70, 72, 78, 80 by a distance at least sufficient to match the width of the workpiece 100, and may extend beyond that width. See Figures 11, 14 and 15. The plurality of magnetic forks 84 need not encompass 20 the surfaces of the connecting inductor segments 74, 76. As shown in FIG. 1, each of the magnetic horns 84 extends through its associated elongate induction segment. The fork 84 already has an interior space 83 inside of which the elongated induction segments can be adjusted. The interior space 83 can be filled with non-magnetic non-conductive material, such as ceramic. Adjacent the lower space 83 there are projections (15) encompassing the edges of the elongated induction segment, the outer material 88 protects both the magnetic forks 84 and the elongate heat induction segment of the workpiece 100. Referring to FIG. Figures 11, 12 and 14, a magnetic field reducer 86 and magnetic shunts 92, 93 are used to direct the magnetic fields to the respective ends of the coil apparatus .. The magnetic field reducer 86 is a magnetic element in the form of a magnetic field. box that is placed inside the space 82 at the open end of the coil apparatus As shown in figure 11, the magnetic field reducer 86 is disposed between two connecting inductor segments 74, 76 (shown comprising several conductors) at the end of the coil apparatus, concentrating the magnetic field produced by the connecting segments 74, 76 between a small area in close proximity to the coil. Depending on its size, the magnetic field reducer 86 may require active cooling by pumping water or other coolant through one or more channels within a faithful reducer during operation. The magnetic field reducer 86 does not make any contact with the induction segments of the coil, remaining separated by a small air space from the connecting duct segments, as shown in Figures 14 and 15, the magnetic shunts 92, 93 are used at the opposite end of the coil from the inductors 74, 76 and the magnetic field reducer 86. the magnetic shunts 92, 93 are magnetic elements placed in close proximity to the closed end of the coil apparatus 69. A magnetic shunt 92 is associated with the power supply terminal of the first and second elongated induction segments 70, 72. The other magnetic shunt 93 is associated with the closed (connected) terminal of the third and fourth elongated induction segments 78, 80. The magnetic leads 92, 93 serve to consign the magnetic field of induction at the closed end and provide magnetic coupling to the magnetic forks 84 r near the end of the coil. Referring to FIGS. 11 and 13, the coil section also comprises segments of heat insulating material 88 disposed respectively on the surface of the firner at four elongated induction segments 70, 72, 78, 80 facing forward (ie. close to) the workpiece 100. This material protects the coil apparatus from damage that could result from being in close proximity to a work item 10. very hot. The magnetic housings 84 of the embodiment of the invention shown in FIG. 15 are directly analogous to the magnetic forks 40 shown in FIG. 2A combined with the transverse forks 34 shown in FIG. 2. The projections 85 on the forks 84 in FIG. Figure 13 serves the purpose of the transverse forks 40 shown in Figure 2A. They avoid the magnetic field created by the inductive effect of the elongated induction segments 70, 72, 78, 80 of the extension of all directions from the edges of the induction segments. The magnetic shunts 92, 93 serve the same purpose at the closed end of the coil apparatus. In this way, the non-negligible components of the magnetic field perpendicular to the longitudinal axis of the workpiece 100, are suppressed by preventing the reliable currents from flowing along the longitudinal ee of the workpiece 100. The present The invention may be encompassed in other specific forms without departing from the spirit or essential attributes of the ism and, therefore, reference should be made to the appended claims rather than the foregoing specification, as indicating the scope of the invention.

Claims (7)

1. eleven NOVELTY OF I A INVENTION CLAIMS 1. An induction heating apparatus for a sheet, slab or bar workpiece having a longitudinal axis comprising: first and second elongate induction segments, each having first and second ends, said first and second elongated induction segments being arranged substantially parallel to each other and extending across opposite surfaces of a workpiece transverse to its longitudinal axis, said first and second elongated segments being connected at their first end by first and second induction segments of uni n? n first end of third and fourth elongated induction segments respectively, said third and fourth elongate induction segments being disposed substantially parallel to each other and extending across opposite surfaces of the workpiece, transverse to its longitudinal axis, said third and fourth induction segments being connected to each other to a second end opposite the first end; a space between said first and second connecting nduction segments, said space having a sufficient dimension to allow the work piece to pass in a skewed manner between the induction segments to be placed inside the coil apparatus, so that the apparatus 12 The coil can move reliably and selectively be removed from the work piece; a plurality of magnetic forks disposed on a surface of the first, second, third and fourth induction segments, respectively, said surface being the surface facing the work piece, said magnetic forks being arranged parallel and spaced apart and parallel to each other; Longitudinal axis of the workpiece, said magnetic forks extending along each of said first to fourth induction segments at a distance at least equal to the width of the work axis; and a magnetic field reducer located within the space of the junction conductors to restrict the magnetic flux out of the induction apparatus.
2. 2. An induction heating apparatus according to claim 1, further characterized in that each of the first to the fourth of said elongated induction segments has a surface facing the workpiece, and the apparatus further comprises terrnoaislanfe material on said surface.
3. 3. The induction heating apparatus of claim 1, further characterized in that it comprises an alternating current power source connected to the second ends of the first and second elongated induction segments.
4. 4. The induction heating apparatus of claim 1, further characterized in that it comprises magnetic de- dancations applied to the second ends of the first and second induction segments and the third and fourth induction segments, respectively.
5. 5. The induction heating apparatus of claim 4, further characterized in that the magnetic shunt on the second ends of the respective first and second induction segments and the third and fourth induction segments are separated from the magnetic forks by material non-conducting.
6. 6. The induction heating apparatus of claim 5, further characterized in that the non-conductive material separating the magnetic forks and the magnetic suspensions is air.
7. 7. The induction heating apparatus of claim 1, further characterized in that the first to fourth induction segments comprise a plurality of conductors. 8. - F1 induction heating apparatus of claim 5, further characterized in that the joint induction elements comprise a plurality of conductors. 9. The induction heating apparatus of claim 1, further characterized in that the magnetic forks are arranged in a plurality of groups spaced along the surface of the first to fourth induction segments. 10. A reliable induction heating apparatus for heating strip material comprising: a first elongate induction segment having first and second ends, a first segment of induction of union having length l connected to said first elongated induction segment in its first end and coplanar with said first segment, forming a substantial angle in the rectilinear connection; a second elongated induction segment having first and second ends arranged parallel to and spaced from the first elongated segment by the length l of the first joint induction segment, said second induction segment being connected at its first end to the first joint segment in a substantially straight and coplanar angle with said joint segment; a third elongated induction segment having first and second ends, said third segment being the second end of the second end connected induction at its first end by a binder segment, said binder being disposed substantially perpendicular segment to a plane extending through both the first and second segments, said third segment being disposed substantially parallel to the second segment and separated from it by the distance la; a second joint segment connected to the second end of the third elongated segment, said second joint segment being disposed parallel to the first joint segment, said second joint segment being separated from the first joint segment by a distance space ls; a fourth elongated induction segment that 15A. has first and second ends, this fourth induction segment being connected at its first end to the second segment of union in? n angle s? bstanci lrnenfe straight to said segment tie union, said fourth segment of induction being arranged parallel to the first segment of induction and separated from it by a distance la; a plurality of magnetic forks disposed on a surface on the first, second, third and fourth induction segments respectively, said surface being the surface in front of the space, said magnetic forks being arranged parallel to and spaced apart and parallel to each other. joining segments of the appendage, said plurality of magnetic forks extending along the dimension of each of the first to fourth induction segments; and a magnetic field reducer located within the space between the link segments to restrict the magnetic flux out of the induction apparatus. 11. An induction heating apparatus according to claim 10, further characterized in that each first to fourth elongated induction segments has one surface facing the other, each of said second and third elongated induction segments has a surface in front of the other, and the apparatus further comprises heat insulating material on said front surfaces of the elongated induction segments. v 12.- The induction heating unit of the 16 claim LO, further characterized in that it comprises an alternating current power source connected to the second extensions of the first to fourth elongated induction segments. 13. The induction heating apparatus of claim 10, further characterized in that it comprises first and second magnetic taps, said first magnetic shunt being disposed on the second ends of the first to fourth induction segments, and said second one. magnetic shunt being disposed on the binder segment connecting one end of the second and third elongated induction segments. 14. The induction heating apparatus of claim 13, further characterized in that the magnetic branches are separated from the magnetic forks by non-conductive material. 15. - The induction heating apparatus of claim 14, further characterized in that the non-conductive material that separates the magnetic forks and the magnetic branches is air. 16. The induction heating apparatus of claim 10, further characterized in that the first to fourth induction segments comprise a plurality of conductors. 17. The induction heating apparatus of claim 16, further characterized in that the joint induction segments comprise a plurality of conductors. 10. - The LO induction heating device, also characterized in that the magnetic forks are arranged in a plurality of groups spaced along the surface of the first to fourth induction segments. 19. A reliable induction heating apparatus to heat strip material comprising: a plurality of elongated induction segments and a plurality of joining segments, said induction segments being arranged in substantially parallel pairs and having first and second ends, each one of the respective segments in each pair being arranged parallel to each other and having a space between them, said parallel pairs of induction segments are connected at their first ends by parallel joining segments so that the joining segments are also separated between yes for a space; each pair of induction segments except one is connected at the second end of the constituent induction segments by a fourth binder segment, said exception pair being connected at its second ends to an AC power source; a plurality of magnetic forks disposed on a surface of the plurality of the respective induction segments, said surface being the surface facing the space, said magnetic forks being arranged parallel to and spaced apart and parallel to the joining segments, said plurality of 10 magnetic forks extending through the elongated dimension of each of said first to fourth induction segments; and a magnetic field reducer Located within the space between the joining elements to restrict the strong magnetic flux of the induction apparatus. 20. An induction heating assembly as in claim 19, further characterized in that each of said elongated induction elements in a pair has a surface facing the space between them, and the apparition also comprises material The insulating surface on said front surface of each constituent elongated induction segment in each respective pair. 21. The induction heating apparatus of claim 19, further characterized in that it comprises an alternating current power source connected to one of the ferrules of the elongated induction segments. 22. The induction heating apparatus of claim 19, further characterized by "? Comprising a plurality of magnetic leads, each of said leads except one is disposed on the tie segments connecting a pair of elongated connectors. 23. The induction heating apparatus of claim 22, further characterized in that said magnetic shunt is disposed on the end of the pair of elongated induction segments that is connected to the power source. 19 24. - The induction heating section of claim 1, further characterized in that the elongated induction segments comprise a plurality of conductor-es. 25. The induction heating apparatus of claim 24, further characterized in that the joining segments comprise a plurality of conductors. 26. The induction heating apparatus of claim 19, further characterized in that the magnetic forks are disposed in a plurality of groups spaced apart along the surface of the first to fourth induction segments. 27. The induction heating apparatus of claim 22, further characterized in that the magnetic branches are separated on the magnetic forks by non-conductive material. 28.- The heating device by means of a jucc? On of the rei indication 27, characterized in that the non-conductive material that separates the magnetic forks and the magnetic branches is the air.