Transverse flux induction heating equipment for heating flat products

Abstract

Induction heating apparatus and methods for use thereof, the apparatus including two poles, each pole including a pair of spaced apart coils, and at least one of the pole spacing and pole pitch adjustable to control the power density delivered across the width of the workpiece, and in some embodiments, a movable flux shield is also adjusted to control the power density delivered along the edge of the workpiece.

Description

[Background technology]

[0001] Induction heaters are suitable for heating conductive, continuous, flat strip or plate products of various thicknesses and widths, as shown in Figure 1. Conventional induction heating uses a solenoid-type coil wound around the strip or plate, as shown in Figure 2. Figure 1 illustrates heating a strip or plate width. Figure 2 illustrates a conventional solenoid coil wound around the plate. When an alternating current is applied to the coil, an electromagnetic field is generated. This reflects the current in the coil, inducing eddy currents around the plate surface, causing Joule heating of the plate. Solenoid coil heating systems have several drawbacks, making them an undesirable choice for this particular application. The first problem is that the thinner the plate, the higher the induction frequency required for efficient inductive coupling. At the same time, the frequency must be selected so that it is not so high that the edges of the plate overheat or the surface overheats before the core of the plate heats up. This requires very high frequencies to heat thin plates, while lower frequencies are required to heat thick plates. A wide frequency range may be required from a single power source, or multiple power sources with different frequencies may be required for each plate thickness to be heated. In these situations, induction heating may not be cost-effective. Furthermore, for very thin plates, the frequencies required to efficiently heat the strip with conventional solenoid coil induction techniques may be higher than those reasonably available, making induction heating an option.

[0002] Transverse flux induction heating is known. For example, U.S. Patent No. 9,462,641, incorporated herein by reference in its entirety, discloses a transverse induction heating apparatus that can be used to heat strips of sheet material. Current transverse induction heating apparatus lack the ability to accurately and precisely control the power density delivered along the length of the sheet, often resulting in either overheating the edge portions of the strip or underheating the center portion of the strip. Furthermore, current transverse induction heating apparatuses are generally only capable of accommodating a narrow range of strip material sizes. Summary of the Invention [Means for solving the problem]

[0003] The present disclosure provides an induction heating apparatus and method of use, the apparatus including two poles, each pole including a pair of spaced apart coils, where at least one of the inter-pole spacing and pole pitch is adjustable to control the power density delivered across the width of the workpiece. In some embodiments, a movable flux shield is also adjusted to control the power density delivered along the edge of the workpiece.

[0004] According to one aspect of the present disclosure, there is provided a transverse flux electric induction coil assembly for inductively heating at least a portion of an associated flat workpiece moving along a process direction relative to the transverse flux electric induction coil assembly, the associated workpiece having opposing first and second workpiece faces and first and second workpiece edges, the induction heating apparatus including first and second planar coils disposed in a first common plane spaced apart from the first workpiece face, extending between the first and second workpiece edges, and electrically coupled in series, the first and second planar coils being spaced apart in the same plane, and at least one of the first and second planar coils being movable within the common plane to change the spacing therebetween.

[0005] At least one of the first planar coil and the second planar coil is adjustable to change the coil pitch. The first planar coil may be formed from a first outward leg and a first return leg extending in a common direction and in a spaced-apart relationship. The first outward leg and the first return leg may be physically and electrically coupled to a first end rail, and at least one of the first outward leg and the first return leg may be movably attached to the first end rail so that the first outward leg and the first return leg move toward and away from each other to change the coil pitch of the first planar coil. The second planar coil may be formed from a second outward leg and a second return leg extending in a common direction and in a spaced-apart relationship. The second outward leg and the second return leg may be physically and electrically coupled to a second end rail, and at least one of the second outward leg and the second return leg may be movably attached to the second end rail so that the second outward leg and the second return leg move toward and away from each other to change the coil pitch of the second planar coil.

[0006] The first planar coil and the second planar coil may each be coupled to a first common rail, with at least one of the first coil or the second coil supported on the first common rail for movement toward or away from the other of the first or second coil. A first return leg of the first coil and a second outward leg of the second coil may be coupled to the first common rail, with at least one of the first return leg and the second outward leg being movable relative to the common rail to vary the distance between the first planar coil and the second planar coil.

[0007] The assembly may further include a third planar coil and a fourth planar coil disposed in a second common plane opposite the second workpiece surface and spaced apart from the first and second workpiece edges, extending between the first and second workpiece edges and electrically coupled in series with the first and second planar coils. The third planar coil and the fourth planar coil are spaced apart coplanarly within the second common plane and movable within the second common plane to vary the spacing therebetween. The third planar coil and the fourth planar coil are spaced apart coplanarly within the second common plane, and at least one of the third planar coil and the fourth planar coil is movable within the second common plane to vary the spacing therebetween. At least one of the third planar coil and the fourth planar coil is adjustable to change the coil pitch.

[0008] The third planar coil is formed from a third outward leg and a third return leg extending in a common direction and in a spaced-apart relationship, the third outward leg and the third return leg being physically and electrically coupled to a third end rail. At least one of the third outward leg and the third return leg may be movably attached to the third end rail such that the third outward leg and the third return leg move toward and away from each other to change the coil pitch of the third planar coil. The fourth planar coil is formed from a fourth outward leg and a fourth return leg extending in a common direction and in a spaced-apart relationship, the fourth outward leg and the fourth return leg being physically and electrically coupled to a fourth end rail. At least one of the fourth outward leg and the fourth return leg may be movably attached to the fourth end rail such that the fourth outward leg and the fourth return leg move toward and away from each other to change the coil pitch of the fourth planar coil.

[0009] The third planar coil and the fourth planar coil may each be coupled to a second common rail, with at least one of the third planar coil or the fourth planar coil being supported on the second common rail for movement toward or away from the other of the third or fourth planar coil. A third return leg of the third coil and a fourth outward leg of the fourth coil may be coupled to the second common rail, with at least one of the third return leg and the fourth outward leg being movable relative to the second common rail to vary the distance between the third planar coil and the fourth planar coil. The return leg of the second planar coil and the outward leg of the third planar coil may be rigidly coupled.

[0010] The assembly may further include at least one magnetic flux shield spaced apart between the first common plane and a surface of the first workpiece facing at least one of the first and second workpiece edges, wherein at least one of the magnetic flux shields is movable laterally of the associated workpiece.

[0011] According to another aspect, a transverse flux electric induction coil assembly for inductively heating at least a portion of an associated flat workpiece moving along a process direction relative to the transverse flux electric induction coil assembly, the associated workpiece having opposing first and second workpiece faces and first and second workpiece edges, the associated workpiece including first and second planar coils disposed in opposing first common planes spaced apart from the first workpiece faces, extending between the first and second workpiece edges, and electrically coupled in series, at least one of the first and second planar coils being adjustable to vary coil pitch.

[0012] The first planar coil is formed from a first outward leg and a first return leg extending in a common direction and in a spaced-apart relationship, the first outward leg and the first return leg being physically and electrically coupled to a first end rail. At least one of the first outward leg and the first return leg can be movably attached to the first end rail such that the first outward leg and the first return leg move toward and away from each other to change the coil pitch of the first planar coil. The second planar coil is formed from a second outward leg and a second return leg extending in a common direction and in a spaced-apart relationship, the second outward leg and the second return leg being physically and electrically coupled to a second end rail. At least one of the second outward leg and the second return leg can be movably attached to the second end rail such that the second outward leg and the second return leg move toward and away from each other to change the coil pitch of the second planar coil.

[0013] The assembly may further include a third planar coil and a fourth planar coil disposed in a second common plane spaced apart from the second workpiece surface, extending between the first and second workpiece edges and electrically coupled in series with the first and second planar coils. At least one of the third planar coil and the fourth planar coil is adjustable to change a coil pitch. The third planar coil is formed from a third outward leg and a third return leg extending in a common direction and in a spaced-apart relationship, the third outward leg and the third return leg being physically and electrically coupled to a third end rail. At least one of the third outward leg and the third return leg may be movably mounted to the third end rail such that the third outward leg and the third return leg move toward and away from each other to change the coil pitch of the third planar coil. The fourth planar coil is formed from a fourth outward leg and a fourth return leg extending in a common direction and in a spaced-apart relationship, the fourth outward leg and the fourth return leg being physically and electrically coupled to a fourth end rail, and at least one of the fourth outward leg and the fourth return leg may be movably mounted to the fourth end rail such that the fourth outward leg and the fourth return leg move toward and away from each other to change the coil pitch of the fourth planar coil.

[0014] According to another aspect, a method of inductively heating an associated strip workpiece includes supplying current to a transverse flux electric induction coil assembly to inductively heat at least a portion of the associated strip workpiece moving along a process direction relative to the transverse flux electric induction coil assembly, the associated strip workpiece having opposing first and second workpiece faces and first and second workpiece edges; The induction heating apparatus includes a first planar coil and a second planar coil disposed in a first common plane facing the first workpiece surface at a distance from the first workpiece surface, extending between the first and second workpiece edges, and electrically coupled in series, the first planar coil and the second planar coil disposed in the same plane at a distance from each other, and at least one of the first planar coil and the second planar coil is movable within the common plane to change the spacing therebetween and adjust the spacing between the first coil and the second coil. At least one of the first planar coil and the second planar coil is adjustable to change the coil pitch, and the method can further include adjusting the pitch of at least one coil. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of a sheet material to be heated, according to an aspect of the present disclosure.

[0016] [Figure 2] FIG. 1 is a perspective view of a conventional solenoid coil wrapped around a sheet of material to be heated.

[0017] [Figure 3] FIG. 1 is a perspective view of a transverse flux wide oval coil for heating strip material.

[0018] [Figure 4] FIG. 4 is a perspective view showing an alternating current flowing through the coil of FIG. 3.

[0019] [Figure 5] 4 is a perspective view of the current generated in the strip material by the coil of FIG. 3.

[0020] [Figure 6] FIG. 1 is a perspective view of a pair of wide oval coils on each side of the strip material.

[0021] [Figure 7a] 7 is a plan view showing an alternating current flowing through the coil of FIG. 6.

[0022] [Figure 7b] FIG. 10 is a plan view showing an alternating current flowing through the coil of a split return inductor.

[0023] [Figure 8a] FIG. 7c is a plan view showing the current generated in the strip using the split return transverse flux inductor of FIG. 7b.

[0024] [Figure 8b] FIG. 10 is a plan view showing the power density generated in the strip by a split-return transverse flux inductor.

[0025] [Figure 9a] FIG. 1 is a perspective view showing a first configuration of a pair of wide oval coils on each side of the strip material.

[0026] [Figure 9b] FIG. 10 is a perspective view showing a second configuration of a pair of wide oval coils on each side of the strip material.

[0027] [Figure 10a] FIG. 1 is a perspective view showing a first configuration of a pair of wide oval coils and flux shields on each side of the strip material.

[0028] [Figure 10b]FIG. 10 is a perspective view showing a second configuration of a pair of wide oval coils and flux shields on each side of the strip material.

[0029] [Figure 11a] FIG. 1 is a perspective view showing a first configuration of a pair of wide oval coils and flux shields on each side of a narrow strip of material.

[0030] [Figure 11b] FIG. 10 is a perspective view showing a second configuration of a pair of wide oval coils and flux shields on each side of a narrow strip of material.

[0031] [Figure 12] FIG. 1 is a perspective view of an inductor assembly having a stack of magnetic laminations disposed outside the coil assembly.

[0032] [Figure 13] FIG. 1 is a perspective view of an exemplary induction heating assembly according to the present disclosure.

[0033] [Figure 14] FIG. 2 is another perspective view of an exemplary induction heating assembly according to the present disclosure.

[0034] [Figure 15] FIG. 15 is a perspective view of the exemplary induction heating assembly and strip of sheet material of FIGS. 13 and 14.

[0035] [Figure 16] FIG. 16 is a perspective view of the exemplary induction heating assembly of FIG. 15 in a first configuration.

[0036] [Figure 17] FIG. 16 is a perspective view of the exemplary induction heating assembly of FIG. 15 in a second configuration.

[0037] [Figure 18]FIG. 16 is a perspective view of the example induction heating assembly of FIG. 15 with a movable flux shield in a first configuration.

[0038] [Figure 19] FIG. 19 is a perspective view of the exemplary induction heating assembly of FIG. 18 with the movable flux shield in a second configuration.

[0039] [Figure 20] FIG. 19 is a perspective view of the example induction heating assembly of FIG. 18 with a movable magnetic flux shield in a third configuration relative to the elongated strip of sheet material.

[0040] [Figure 21] 10 is a graph showing the effect of pole pitch width adjustment.

[0041] [Figure 22] 10 is a graph showing the effect of adjusting the split return gap.

[0042] [Figure 23] 10 is a graph showing the effect of adjusting magnetic flux shield overlap. DETAILED DESCRIPTION OF THE INVENTION

[0043] In the drawings, like reference numerals refer to like elements throughout, and various features are not necessarily drawn to scale. Additionally, the terms "couple" or "couples" include indirect or direct electrical or mechanical connections, or combinations thereof. For example, when a first device couples to or is coupled with a second device, the connection may be through a direct electrical connection or through an indirect electrical connection via one or more intervening devices and connections. One or more operating characteristics of various circuits, systems, and / or components are described below in terms of their functionality, which is sometimes a result of the configuration and / or interconnection of various structures when the circuit is powered and operating.

[0044] Due to the problems with solenoid induction heating described above, transverse flux technology has replaced traditional solenoid heating techniques, especially for very thin strips and plates. Many different transverse flux designs have been developed. Many of these designs require many moving parts, making them very cumbersome and high-maintenance. In one example, flat strips / plates are heated using a transverse flux design, which utilizes the available frequency range from a single power source, allowing for efficient heating of all plate / strip sizes, with the option of either a single frequency or small variations in frequency. It is desirable to heat at the lowest possible frequency without overheating any part of the plate. A second drawback of using solenoid coils is that the coil wraps around the plate, making it difficult to handle the plate from heating to the bending process. In the case of strip, the coil cannot be removed while the continuous strip remains inside. When the workpiece is very wide, a typical in-line seam annealing coil cannot be designed to heat the entire width uniformly. Therefore, it would be beneficial to use an induction heating coil configuration that does not surround the plate / strip to be heated.

[0045] Referring also to Figures 3-5, one embodiment of the present disclosure provides a transverse flux coil designed so that a strip S passes between a pair of wide-oval coils C, collectively referred to as poles P, as shown in Figure 3. Figure 3 illustrates a simple transverse flux induction heating coil setup showing the configuration of the poles P in relation to the strip. Figure 4 illustrates the applied current to the wide-oval coils C. Figure 5 illustrates the current flow occurring on the strip surface (typically on each side). Generally, although not a strict requirement for all possible implementations, the coils C are positioned directly alongside each other on either side of the strip, or as mirror images of each other. The coils C are electrically connected in series with each other so that the currents in the coils C on either side of the strip are electrically in phase with each other, as shown in Figure 4. This results in an induced current flowing in the strip, as shown in Figure 5.

[0046] Referring also to Figures 6, 7a, and 7b, in one example, each side of the strip is provided with a pair of wide-oval transverse flux coils C that form at least two poles P1 and P2. Each coil C is electrically connected in series and in phase with each surface, as shown in Figure 7a, and operates like a split-return inductor. Figure 7b illustrates the configuration and current flow of a typical split-return inductor. Figures 7a and 7b each illustrate that the coil configuration of the present disclosure (Figure 7a) is designed to operate inductively like a conventional split-return inductor (Figure 7b).

[0047] Figures 8a and 8b show the current developed in the strip using a split-return transverse-flux inductor (Figure 8a) and the power density developed in the strip by a split-return transverse-flux inductor (Figure 8b), respectively. With a split-return inductor, the primary heating of the strip typically occurs along the middle of the inductor assembly, where the current is twice / effectively twice that of the outer legs of the inductor. Since power is proportional to the square of the current times the resistance (P=I 2R), doubling the current density along the center conductor of a pole pair will quadruple the power generated in the strip. In a typical split-return design transverse flux inductor, the induced currents will be similar to those shown in Figure 8a, resulting in the relative power density distribution in the strip shown in Figure 8b.

[0048] Figures 9a and 9b show that the heating pattern can be changed across the width of the strip by adjusting the spacing between the poles P1 and P2 of the transverse inductor, as shown in Figure 7a. In this example, the ability to adjust the spacing SP between each of the center legs of the wide oval coil C is provided, as shown in Figures 9a and 9b. This ability allows for the adjustment of the power density across the strip, and therefore the thermal profile across the strip.

[0049] As further shown in FIGS. 10a, 10b, 11a, and 11b, a further embodiment provides one or more magnetic flux shields SH made from a highly conductive material. As shown in FIGS. 10(a) and 10(b), the shields SH are positioned between the strip to be heated and the coil C. The shields SH are movable (e.g., along the plate length as shown in FIG. 1) and are used to shield the edges of the strip from the electromagnetic field to minimize overheating of the edges of the strip. The shields SH are adjustable to provide the same function for narrower strips, as shown in FIGS. 11(a) and 11(b). FIGS. 10a and 10b show an adjustable magnetic flux shield SH provided to control strip edge temperature. FIGS. 11a and 11b illustrate that the magnetic flux shield SH is adjustable to perform the same function for narrower strips.

[0050] 12, the disclosed concepts in certain examples may also include stacked magnetic lamination sheets LS positioned outside the coil, away from the strips, as shown in FIG. 12. This lamination helps to improve the efficiency of the inductor and minimize stray fields outside the coil C that may induce heat in other conductive objects outside the inductor. FIG. 12 shows an inductor assembly shown with a stack of magnetic laminations LS positioned outside the coil assembly.

[0051] 13-20 illustrate various aspects of an exemplary embodiment of an induction heating assembly of the present disclosure, generally identified by the reference numeral 50, having two poles 52A and 52B, and allowing for adjustment of a split return gap, adjustment of the pole pitch of one or both poles, and / or adjustment of one or more flux shield positions, all of the above, to accommodate more uniform heating of a wide range of strip widths within a single induction heating assembly.

[0052] The general components of the induction heating assembly 50 will be introduced in the order of current flow through the assembly, followed by a description of the function of the induction heating assembly 50. The current flow through the assembly is indicated by arrow A in FIG. 13. The pole 52A includes a first coil C1 having an outwardly extending leg 54 with a first (proximal) end 56 that receives current from a suitable power source (not shown). As used herein, the terms proximal end and distal end, with respect to the legs of the coil, are taken in the direction of current flow, with the proximal end referring to the end of the leg that receives current and the distal end referring to the end of the leg from which current exits the leg. As such, the leg 54 is movably supported at and electrically coupled to a second (distal) end 58 by an end rail or guide member 60. The rail 60 is electrically conductive or includes an electrically conductive structure that electrically couples the leg 54 to a return leg 62. The distal end of the return leg 62 is movably supported at and electrically coupled to a common rail or guide member 64. Common rail 64 is conductive or includes conductive structure that electrically couples leg 62 of coil C1 to outward leg 66 of coil C2. Outward leg 66 is electrically coupled to end rail or guide 68. Rail 68 is conductive or includes conductive structure that electrically couples leg 66 to return leg 70 of coil C2. Coil C2 is electrically coupled to coil C3 of pole 52B via connector 74. Outward leg 76 of coil C3 is electrically coupled to end rail 78. Rail 78 is conductive or includes conductive structure that electrically couples outward leg 76 to return leg 80. Return leg 80 is electrically coupled to common rail or guide member 82 that electrically couples coil C3 to outward leg 84 of coil C4. Outward leg 84 is electrically coupled to end rail 86 that is conductive or includes conductive structure that electrically couples leg 84 to return leg 88 of coil C4. In this description, the term common rail is used for the rail or guide member that joins the coils of adjacent poles, and the term end rail is used for the rail or guide member that joins the outward and return legs of a particular coil.

[0053] As will be appreciated, the coils C1, C2, C3, and C4 are connected in series, and the outward and return legs of each coil pair (C1 / C4, C2 / C3) are arranged such that, on each side of the sheet to be heated, current flows in a common direction through the outward legs of each coil pair and in a common direction through the return legs of each coil pair.

[0054] Each of the outward legs 54, 66, 76, and 84 has a distal end slidably coupled to a respective end rail, while each of the return legs 62, 70, 80, and 88 has a proximal end fixedly coupled to a respective end rail, while each of the outward legs 66 and 84 has a proximal end slidably coupled to a respective common rail. Thus, the sliding end rail connection facilitates moving the respective outward and return legs of the coil toward or away from each other to adjust the coil pitch, and the sliding common rail connection facilitates moving the poles toward or away from each other to adjust the split return gap.

[0055] 14, it can be seen that relative movement of the outboard legs 54, 66, 76, 84 with respect to the return legs 62, 70, 80, 88 facilitates changing at least one of the split return gap (e.g., the spacing between poles 52A and 52B) and the pole pitch (e.g., the spacing between the outboard and return legs of the poles). Sliding of the outboard legs on the end rails primarily affects the change in pole pitch, while sliding of the return legs 62 and 84 on their respective common rails primarily affects the change in split return gap.

[0056] Figures 15-17 show examples of possible adjustments to pole pitch and / or split return gap. In Figure 15, poles 52A and 52B have a first pole pitch and are spaced apart by a first split return gap. In Figure 16, the pole pitch of poles 52A and 52B is the same as in Figure 15, but the split return gap is reduced by moving poles 52A and 52B closer together. In Figure 17, the split return gap between poles 52A and 52B is the same as in Figure 16, but the pole pitch of each pole 52A and 52B is reduced by sliding outward legs 66, 84 on a common rail. It will be appreciated that adjusting the pole pitch and / or split return gap can concentrate or disperse the magnetic flux generated by the coil, thereby enabling the assembly to more precisely heat a wider range of strip material widths and thicknesses and / or heat a given strip more uniformly.

[0057] 18-20, an exemplary assembly 50 is shown having a flux shield SH positioned between the coils C1-C4 and the sheet material SM. The flux shield SH is generally aligned along the end rails and common rail and is generally sized and shaped to anticipate the longitudinal edge portions of the sheet material to prevent overheating of such edges. In FIGS. 18 and 19, a relatively wide strip of sheet material SM is shown, with the flux shield SH overlapping more of the sheet material SM in FIG. 19 than in FIG. 18. In FIG. 20, a relatively narrow strip of sheet material SM is shown, with the flux shield SH moved inward to cover at least a portion of the longitudinal edge of the sheet material SM.

[0058] It should be appreciated that a wide range of actuators can be used to make the adjustments described in the previous paragraph, such as linear actuators, servos, etc. In some embodiments, some or all of the adjustments can be made manually. In other examples, various sensors can be used to sense the condition of the sheet material and adjust one or more parameters of the assembly 50 in real time in response to the sensed data. For example, various thermal sensors can be used to monitor the temperature of the strip, identify hot or cold areas, and adjust the assembly 50 to eliminate or reduce such areas. Edge tracking sensors can be used to identify the edges of the sheet material and more precisely position the flux shield.

[0059] Referring to Figures 21-23, the effects of the above adjustments, pole pitch, split return gap, and shield position are shown in graphical form for a strip of sheet material of a given width. Each graph plots position across the strip width on the X-axis and the time-averaged relative power density transferred to the strip on the Y-axis. In Figure 21, various pole pitches are graphed, including a wide pole pitch (dotted line), a center pole pitch (dashed line), and a narrow pole pitch (solid line). As can be seen, the lines meet at the centerline of the strip and diverge toward the edge of the strip, with a wide pole pitch transferring the most power density to the edge and a narrow pole pitch transferring the least power density to the edge. In Figure 22, various split return gaps are graphed, including a large split return gap (dotted line) and a small split return gap (solid line). As can be seen, the lines meet at the centerline of the strip and diverge toward the edge of the strip, with a large split return gap transferring the most power density to the edge and a small split return gap transferring the least power density to the edge. It should be recognized that, in general, a change in pole pitch will result in a larger overall change in power density transfer compared to a change in split return gap.

[0060] Therefore, adjusting the pole pitch width can be thought of as a coarse adjustment, and adjusting the split return gap as a fine adjustment.In practice, therefore, the pole pitch can first be set to a width to achieve a baseline power density transfer, and then the split return gap can be used to fine-tune the power density transfer.

[0061] Figure 23 shows two different flux shield overlaps: reduced overlap (dashed line) and increased gap (solid line). Reducing the overlap results in greater power density transfer at the strip edges. Flux shield overlap can be used in conjunction with adjusting pole pitch and split return gap to fine-tune power density transfer for a given strip size.

[0062] The described examples are subject to modification and other implementations are possible within the scope of the claims.

Claims

1. 1. A transverse flux electric induction coil assembly for inductively heating at least a portion of an associated flat workpiece moving along a process direction relative to the transverse flux electric induction coil assembly, comprising: the associated workpiece having opposing first and second workpiece faces and first and second workpiece edges; Transverse flux induction coil assembly for induction heating a first planar coil and a second planar coil disposed in a first common plane spaced apart from the first workpiece surface, extending between the first and second workpiece edges, and electrically coupled in series; a third planar coil and a fourth planar coil disposed in a second common plane spaced apart from and facing the second workpiece surface, the third planar coil and a fourth planar coil extending between the first and second workpiece edges and electrically coupled in series with the first and second planar coils; the first planar coil and the second planar coil are disposed on the same plane in the first common plane with a gap therebetween, and at least one of the first planar coil and the second planar coil is movable in the first common plane to change a gap between the first planar coil and the second planar coil; the first planar coil having a first outward leg and a first return leg in the first common plane; the second planar coil having a second outward leg and a second return leg in the first common plane; the first return leg is a first central leg that is closer to the second planar coil; the second return leg is a second central leg that is closer to the first planar coil; The first central leg and the second central leg are configured to pass current in the same direction, the first outward leg and the first return leg are physically and electrically coupled; the second outward leg and the second return leg are physically and electrically coupled; a first return leg of the first planar coil and a second outward leg of the second planar coil are coupled together; the third planar coil and the fourth planar coil are disposed coplanarly within the second common plane and spaced apart, and at least one of the third planar coil and the fourth planar coil is movable within the second common plane to change a spacing between the third planar coil and the fourth planar coil; the third planar coil having a third outward leg and a third return leg in the second common plane; the fourth planar coil having a fourth outward leg and a fourth return leg in the second common plane; the third return leg is a third central leg that is closer to the fourth planar coil; the fourth return leg is a fourth central leg that is closer to the third planar coil; the third central leg and the fourth central leg are configured to pass a current in the same direction as the first central leg and the second central leg; the third outward leg and the third return leg are physically and electrically coupled; the fourth outward leg and the fourth return leg are physically and electrically coupled; the third return leg of the third planar coil and the fourth outward leg of the fourth planar coil are coupled together; the second return leg of the second planar coil and the third outward leg of the third planar coil are electrically coupled to each other at a distance that allows a workpiece to be placed therebetween; Transverse flux induction coil assembly.

2. At least one of the first planar coil and the second planar coil is adjustable to change the coil pitch.

10. The transverse flux induction coil assembly of claim 1.

3. the first outward leg and the first return leg extend in a common direction and are in a spaced apart relationship; the first outward leg and the first return leg are physically and electrically coupled to a first end rail, and at least one of the first outward leg and the first return leg is movably attached to the first end rail such that the first outward leg and the first return leg move toward and away from each other to change the coil pitch of the first planar coil; the second outward leg and the second return leg extend in a common direction and are in a spaced apart relationship; the second outward leg and the second return leg are physically and electrically coupled to a second end rail, and at least one of the second outward leg and the second return leg is movably attached to the second end rail such that the second outward leg and the second return leg move toward and away from each other to change the coil pitch of the second planar coil.

3. The transverse flux induction coil assembly of claim 2.

4. the first planar coil and the second planar coil are each coupled to a first common rail, and at least one of the first planar coil or the second planar coil is supported on the first common rail so as to be movable toward or away from the other of the first or second planar coil.

4. The transverse flux induction coil assembly of claim 3.

5. a first return leg of the first planar coil and a second outward leg of the second planar coil are coupled to the first common rail, and at least one of the first return leg and the second outward leg is movable relative to the first common rail to vary the distance between the first planar coil and the second planar coil; 5. The transverse flux induction coil assembly of claim 4.

6. At least one of the third planar coil and the fourth planar coil is adjustable to change the coil pitch.

10. The transverse flux induction coil assembly of claim 1.

7. the third outward leg and the third return leg extend in a common direction and are in a spaced apart relationship; the third outward leg and the third return leg are physically and electrically coupled to a third end rail, and at least one of the third outward leg and the third return leg is movably attached to the third end rail such that the third outward leg and the third return leg move toward and away from each other to change the coil pitch of the third planar coil; the fourth outward leg and the fourth return leg extend in a common direction and are in a spaced apart relationship; the fourth outward leg and the fourth return leg are physically and electrically coupled to a fourth end rail, and at least one of the fourth outward leg and the fourth return leg is movably attached to the fourth end rail such that the fourth outward leg and the fourth return leg move toward and away from each other to change the coil pitch of the fourth planar coil.

7. The transverse flux induction coil assembly of claim 6.

8. the third planar coil and the fourth planar coil are each coupled to a second common rail, and at least one of the third planar coil or the fourth planar coil is supported on the second common rail so as to be movable toward or away from the other of the third or fourth planar coil.

8. The transverse flux induction coil assembly of claim 7.

9. the third return leg of the third planar coil and the fourth outward leg of the fourth planar coil are coupled to the second common rail, and at least one of the third return leg and the fourth outward leg is movable relative to the second common rail to vary the distance between the third planar coil and the fourth planar coil.

9. The transverse flux induction coil assembly of claim 8.

10. the second return leg of the second planar coil and the third outward leg of the third planar coil are rigidly coupled.

10. The transverse flux induction coil assembly of claim 9.

11. at least one magnetic flux shield spaced apart between the first common plane and the first workpiece surface facing at least one of the first and second workpiece edges; At least one of the flux shields is movable laterally of the associated workpiece.

10. The transverse flux induction coil assembly of claim 1.

12. A method of induction heating an associated strip workpiece, comprising: supplying current to the transverse flux electric induction coil assembly to inductively heat at least a portion of the associated strip workpiece moving along a process direction relative to the transverse flux electric induction coil assembly, the associated strip workpiece having opposing first and second workpiece faces and first and second workpiece edges; Induction heating equipment first and second planar coils disposed in a first common plane spaced apart from and facing the first workpiece surface, extending between the first and second workpiece edges, and electrically coupled in series; a third planar coil and a fourth planar coil disposed in a second common plane spaced apart from and facing the second workpiece surface, the third planar coil and a fourth planar coil extending between the first and second workpiece edges and electrically coupled in series with the first and second planar coils; the first planar coil and the second planar coil are coplanarly spaced apart within the first common plane, and at least one of the first planar coil and the second planar coil is movable within the first common plane to change a spacing between the first planar coil and the second planar coil; adjusting a spacing between the first planar coil and the second planar coil; the first planar coil having a first outward leg and a first return leg in the first common plane; the second planar coil having a second outward leg and a second return leg in the first common plane; the first return leg is a first central leg that is closer to the second planar coil; the second return leg is a second central leg that is closer to the first planar coil; The first central leg and the second central leg are configured to pass current in the same direction, the first outward leg and the first return leg are physically and electrically coupled; the second outward leg and the second return leg are physically and electrically coupled; a first return leg of the first planar coil and a second outward leg of the second planar coil are coupled together; the third planar coil and the fourth planar coil are disposed coplanarly within the second common plane and spaced apart, and at least one of the third planar coil and the fourth planar coil is movable within the second common plane to change a spacing between the third planar coil and the fourth planar coil; the third planar coil having a third outward leg and a third return leg in the second common plane; the fourth planar coil having a fourth outward leg and a fourth return leg in the second common plane; the third return leg is a third central leg that is closer to the fourth planar coil; the fourth return leg is a fourth central leg that is closer to the third planar coil; the third central leg and the fourth central leg are configured to pass a current in the same direction as the first central leg and the second central leg; the third outward leg and the third return leg are physically and electrically coupled; the fourth outward leg and the fourth return leg are physically and electrically coupled; the third return leg of the third planar coil and the fourth outward leg of the fourth planar coil are coupled together; the second return leg of the second planar coil and the third outward leg of the third planar coil are electrically coupled to each other at a distance that allows a workpiece to be placed therebetween; method.

13. At least one of the first planar coil and the second planar coil is adjustable to change a coil pitch, further comprising adjusting the pitch of at least one coil. The method of claim 12.

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