TRANSVERSE FLUX INDUCTION HEATING DEVICE

Abstract

Volumes of cores (1120, 1220) are made to differ between a heating upstream-side region and a heating downstream-side region.

Claims

1.-16. (canceled)

17. A transverse flux induction heating device comprising an upper inductor and a lower inductor arranged to face each other while sandwiching a conductor plate therebetween, and performing induction heating on the conductor plate by making alternating magnetic fields intersect a plate surface of the conductor plate, wherein: each of the upper inductor and the lower inductor has a coil and a core; a volume of one piece of the core provided to the upper inductor and a volume of one piece of the core provided to the lower inductor are respectively different between a heating upstream-side region of the one piece of core and a heating downstream-side region of the one piece of core; the heating upstream-side region of the core is a region on an upstream side in a conveyance direction of the conductor plate relative to a reference position of the core; the heating downstream-side region of the core is a region on a downstream side in the conveyance direction of the conductor plate relative to the reference position of the core; the reference position of the core is a center position in a heating length direction between a most upstream end position of coil of the core and a most downstream end position of coil of the core; the heating length direction is a direction parallel to the conveyance direction of the conductor plate; the most upstream end position of coil of the core is a position of an end portion positioned on the most upstream side in the heating length direction, out of end portions of the coil arranged with respect to the core; the most downstream end position of coil of the core is a position of an end portion positioned on the most downstream side in the heating length direction, out of end portions of the coil arranged with respect to the core; a same main magnetic flux flows through one piece of the core provided to the upper inductor; a same main magnetic flux flows through one piece of the core provided to the lower inductor; and the main magnetic flux is a magnetic flux that passes through the conductor plate.

18. The transverse flux induction heating device according to claim 17, wherein: each of the upper inductor and the lower inductor has a leakage flux reducing member for reducing a leakage flux; the leakage flux includes a magnetic flux that does not pass through the conductor plate, out of magnetic fluxes generated from the core; the leakage flux reducing member is arranged in a heating amount decreased region; and the heating amount decreased region is a region with smaller volume of the core, out of the heating upstream-side region and the heating downstream-side region.

19. The transverse flux induction heating device according to claim 18, wherein the leakage flux reducing member contains a non-magnetic material.

20. The transverse flux induction heating device according to claim 19, wherein the leakage flux reducing member contains copper.

21. The transverse flux induction heating device according to claim 18, wherein: the leakage flux reducing member is not arranged in a heating amount increased region; and the heating amount increased region is a region with larger volume of the core, out of the heating upstream-side region and the heating downstream-side region.

22. The transverse flux induction heating device according to claim 18, wherein: the leakage flux reducing member is arranged on a back side relative to the coil; and the back side is an opposite side of a side where the conductor plate exists.

23. The transverse flux induction heating device according to claim 18, wherein each of the upper inductor and the lower inductor has an interposed member for electrically insulating the leakage flux reducing member and the coil.

24. The transverse flux induction heating device according to claim 18, wherein: the leakage flux reducing member has one or a plurality of pieces of plate; and a plate surface of the plate is substantially parallel to a plate surface of the conductor plate.

25. The transverse flux induction heating device according to claim 17, wherein: a ratio of the volume of the core in a heating amount increased region to the volume of the core in a heating amount decreased region is 5.1 or more; the heating amount decreased region is a region with smaller volume of the core, out of the heating upstream-side region and the heating downstream-side region; and the heating amount increased region is a region with larger volume of the core, out of the heating upstream-side region and the heating downstream-side region.

26. The transverse flux induction heating device according to claim 17, wherein: the core has: a center-side leg portion arranged in a hollow region of the coil; and a center-side body portion through which a main magnetic flux same as a main magnetic flux that flows through the center-side leg portion flows; a tip face of the center-side leg portion faces the conductor plate in a state of having an interval therebetween; the center-side body portion includes a region on a heating amount increased region side relative to the center-side leg portion; the heating amount increased region is a region with larger volume of the core, out of the heating upstream-side region and the heating downstream-side region; the center-side body portion is arranged on a back side relative to the coil; and the back side is an opposite side of the side where the conductor plate exits.

27. The transverse flux induction heating device according to claim 26, wherein: each of the upper inductor and the lower inductor has a leakage flux reducing member for reducing a leakage flux; the leakage flux includes a magnetic flux that does not pass through the conductor plate, out of magnetic fluxes generated from the core; the leakage flux reducing member is arranged in a heating amount decreased region; the heating amount decreased region is a region with smaller volume of the core, out of the heating upstream-side region and the heating downstream-side region; and a length in the heating length direction of the center-side body portion is longer than a length in the heating length direction of the leakage flux reducing member.

28. The transverse flux induction heating device according to claim 26, wherein: the core has an end-side body portion through which a main magnetic flux same as the main magnetic flux that flows through the center-side body portion flows; and the end-side body portion is arranged on the back side relative to the coil, and arranged on the heating amount increased region side relative to the center-side leg portion and the coil.

29. The transverse flux induction heating device according to claim 28, wherein: the core has an end-side leg portion through which a main magnetic flux same as the main magnetic flux that flows through the end-side body portion flows; the end-side leg portion is arranged on the heating amount increased region side relative to the center-side body portion and the coil, and arranged on the conductor plate side relative to the end-side body portion; and a tip face of the end-side leg portion faces the conductor plate in a state of having an interval therebetween.

30. The transverse flux induction heating device according to claim 29, wherein the coil is arranged on the conductor plate side relative to the tip face of the end-side leg portion.

31. The transverse flux induction heating device according to claim 26, wherein: a portion of the core except for the center-side leg portion and the center-side body portion does not exist in a heating amount decreased region; and the heating amount decreased region is a region with smaller volume of the core, out of the heating upstream-side region and the heating downstream-side region.

32. The transverse flux induction heating device according to claim 17, wherein the volume of the core in the heating downstream-side region is larger than the volume of the core in the heating upstream-side region.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0013] FIG. 1 is a sectional view illustrating one example of a transverse flux induction heating device.

[0014] FIG. 2A is a plan view illustrating one example of the transverse flux induction heating device.

[0015] FIG. 2B is a bottom view illustrating one example of the transverse flux induction heating device.

[0016] FIG. 3 is a back view illustrating one example of the transverse flux induction heating device.

[0017] FIG. 4 is a front view illustrating one example of the transverse flux induction heating device.

[0018] FIG. 5 is a view conceptually illustrating one example of a main magnetic flux that flows through the induction heating device.

[0019] FIG. 6A is a view conceptually illustrating one example of a heating value of a conductor plate that is heated by using the induction heating device of the present embodiment.

[0020] FIG. 6B is a view conceptually illustrating one example of a heating value of a conductor plate that is heated by using two general induction heating devices.

DESCRIPTION OF EMBODIMENTS

[0021] Hereinafter, an embodiment of the present invention will be explained while referring to the drawings.

[0022] Note that when comparison targets such as lengths, positions, sizes and intervals are the same, this means not only a case where they are strictly the same but also a case where they are differed within a range that does not depart from the gist of the invention (differed within a tolerance range defined when designing, for example). Further, in the respective drawings, only a part required for explanation will be illustrated in a simplified manner according to need, for the convenience of explanation and notation. Further, in each drawing, x-y-z coordinates indicate a relation of directions in the drawing. A symbol of white circle () with cross mark () given therein indicates an axis regarding which a direction from a near side toward a far side of the paper sheet is a positive direction. Further, a symbol of white circle () with black circle (.circle-solid.) given therein indicates an axis regarding which a direction from the far side toward the near side of the paper sheet is a positive direction. Further, the present embodiment exemplifies a case where an x-y plane is a horizontal plane, and a z-axis direction is a height direction.

[0023] FIG. 1 to FIG. 4 are views each illustrating one example of a transverse flux induction heating device. The present embodiment exemplifies a case where a conveyance direction of a conductor plate M is a y-axis positive direction, a width direction of the conductor plate M is an x-axis direction, and a plate thickness direction of the conductor plate M is a z-axis direction. In this case, an upstream side in the conveyance direction of the conductor plate M is a y-axis negative direction side, and a downstream side in the conveyance direction of the conductor plate M is a y-axis positive direction side. Here, a direction parallel to the conveyance direction of the conductor plate M (y-axis positive direction) (specifically, the y-axis direction) is set to be referred to as a heating length direction. The heating length direction corresponds to a longitudinal direction of the conductor plate M.

[0024] FIG. 1 illustrates a cross section (y-z cross section) of a transverse flux induction heating device 1000 in a case where the device is cut perpendicular to the width direction of the conductor plate M (x-axis direction). FIG. 2A illustrates a state (plan view) in which the transverse flux induction heating device 1000 is seen from above the device (from the z-axis positive direction side). FIG. 2B illustrates a state (bottom view) in which the transverse flux induction heating device 1000 is seen from below the device (from the z-axis negative direction side). FIG. 3 illustrates a state (back view) in which the transverse flux induction heating device 1000 is seen from the upstream side in the conveyance direction of the conductor plate M (from the y-axis negative direction side). FIG. 4 illustrates a state (front view) in which the transverse flux induction heating device 1000 is seen from the downstream side in the conveyance direction of the conductor plate M (from the y-axis positive direction side). In the explanation below, the conveyance direction of the conductor plate M will be abbreviated to a conveyance direction according to need, the width direction of the conductor plate M will be abbreviated to a width direction according to need, and the plate thickness direction of the conductor plate M will be abbreviated to a plate thickness direction according to need.

[0025] The transverse flux induction heating device 1000 performs induction heating on the conductor plate M by making alternating magnetic fields intersect substantially perpendicular (preferably perpendicular) to a plate surface of the conductor plate M during conveyance. Note that the conductor plate M is a metal plate such as a steel plate, for example. In the following explanation, the transverse flux induction heating device will be abbreviated to an induction heating device, according to need. Hereinbelow, one example of a configuration of the induction heating device 1000 will be explained, Note that dimensions (W.sub.1 to W.sub.5) of the induction heating device 1000 will be described later in a section of (design method).

(Induction Heating Device 1000)

[0026] The induction heating device 1000 has an upper inductor 1100 and a lower inductor 1200. The upper inductor 1100 and the lower inductor 1200 are arranged in a state of having an interval therebetween in the plate thickness direction of the conductor plate M (z-axis direction) so as to face each other while sandwiching the conductor plate M therebetween. As described above, the plate thickness direction of the conductor plate M (z-axis direction) corresponds to the direction in which the upper inductor 1100 and the lower inductor 1200 face each other. In the induction heating device 1000 illustrated in FIG. 1 to FIG. 4, a case is exemplified in which the upper inductor 1100 and the lower inductor 1200 are in a relation of plane symmetry in which a virtual plane SL is set to a plane of symmetry. The virtual plane SL is a plane passing through a center position in the plate thickness direction of the conductor plate M (z-axis direction) and a plane parallel to the width direction (x-axis direction) and the longitudinal direction (y-axis direction). Note that the virtual plane SL is not a real plane.

[0027] The upper inductor 1100 and the lower inductor 1200 have coils 1110, 1210, and cores 1120, 1220, respectively.

[0028] A turn number of each of the coils 1110, 1210 is N (N is an integer of 1 or more). The turn number of the coils 1110, 1210 is not limited. FIG. 1 and FIG. 2 exemplify a case where the turn number N of each of the coils 1110, 1210 is five. The coils 1110, 1210 are respectively arranged so that center lines of the coils 1110, 1210 become substantially orthogonal (preferably orthogonal) to the plate surface of the conductor plate M, for example. The coils 1110, 1210 may be electrically connected in series, or they may also be electrically connected in parallel. In this case, alternating currents that flow through the coils 1110, 1210 are alternating currents supplied from the same alternating-current power supply. Further, the coils 1110, 1210 may not be electrically connected. In this case, the alternating currents that flow through the coils 1110, 1210 are alternating currents supplied from separate alternating-current power supplies. Note that the electrical connection in series means the same as a series connection that is generally used in a field of electric circuit. Further, the electrical connection in parallel means the same as a parallel connection that is generally used in the field of electric circuit. In the explanation below, the electrical connection in series will be simply referred to as a series connection, according to need. Further, the electrical connection in parallel will be simply referred to as a parallel connection, according to need.

[0029] It is only required to realize that directions at the same time of magnetic fluxes generated from the coils 1110, 1210 by the alternating currents that flow through the coils 1110, 1210 from the alternating-current power supply are set to be substantially the same (preferably the same), and alternating magnetic fields generated from the coils 1110, 1210 are made to intersect substantially perpendicular (preferably perpendicular) to the plate surface of the conductor plate M.

[0030] Note that when the coils 1110, 1210 are connected in series in the example illustrated in FIG. 1, FIG. 2A, and FIG. 2B, the turn number of the whole coils 1110, 1210 in the induction heating device 1000 becomes ten (=25). On the other hand, when the coils 1110, 1210 are connected in parallel, the turn number of the whole coils 1110, 1210 in the induction heating device 1000 becomes five.

[0031] FIG. 1 to FIG. 4 exemplify a case where the coils 1110, 1210 are configured by using a copper pipe. The copper pipe has a hollow rectangular parallelepiped shape, for example. A cooling medium (cooling water, for example) is supplied to a hollow portion of the copper pipe. Note that here, in order to simplify the notation, a case is exemplified in which a vortical copper pipe is used to configure the coils 1110, 1210, as illustrated in FIG. 2A and FIG. 2B. However, the configuration of the coils 1110, 1210 is not limited to such a configuration. The induction heating device 1000 may also have a coil having a well-known configuration adopted in induction heating devices.

[0032] The coils 1110, 1210 are arranged in (wound around) the cores 1120, 1220, respectively. The cores 1120, 1220 are configured by using a soft magnetic material. Further, volumes of the cores 1120, 1220 are different between a heating upstream-side region and a heating downstream-side region. The heating upstream-side region is a region on an upstream side (y-axis negative direction side) in the conveyance direction relative to a reference position SP. The heating downstream-side region is a region on a downstream side (y-axis positive direction side) in the conveyance direction relative to the reference position SP. In the explanation below, the upstream side in the conveyance direction and the downstream side in the conveyance direction will be abbreviated to an upstream side and a downstream side, respectively, according to need.

[0033] The reference position SP is a center position in the heating length direction (y-axis direction) between a most upstream end position of coil MU and a most downstream end position of coil MD. The most upstream end position of coil MU is a position of an end portion positioned on the most upstream side (y-axis negative direction side) in the heating length direction (y-axis direction) out of positions of end portions of the coils 1110, 1210. The most downstream end position of coil MD is a position of an end portion positioned on the most downstream side (y-axis positive direction side) in the heating length direction (y-axis direction) out of the positions of the end portions of the coils 1110, 1210.

[0034] As exemplified in FIG. 1, when the number of coils 1110, 1210 arranged in the heating length direction (y-axis direction) with respect to one core 1120, 1220 is one, the most upstream end position of coil MU is a position of the end portion positioned on the most upstream side (y-axis negative direction side) in the heating length direction (y-axis direction), out of the positions of the end portions of the coils 1110, 1210. Further, the most downstream end position of coil MD is a position of the end portion positioned on the most downstream side (y-axis positive direction side) in the heating length direction (y-axis direction), out of the positions of the end portions of the coils 1110, 1210.

[0035] On the other hand, when a plurality of coils are arranged with respect to one core 1120, 1220 so as to be lined while having an interval therebetween in the heating length direction (y-axis direction), the most upstream end position of coil MU is defined in the coil positioned on the most upstream side (y-axis negative direction side) in the heating length direction, out of the plurality of coils. Specifically, the most upstream end position of coil MU is a position of the end portion positioned on the most upstream side in the heating length direction, out of the positions of the end portions of the coil positioned on the most upstream side in the heating length direction. Further, the most downstream end position of coil MD is defined in the coil positioned on the most downstream side (y-axis positive direction side) in the heating length direction, out of the plurality of coils. Specifically, the most downstream end position of coil MD is a position of the end portion positioned on the most downstream side in the heating length direction, out of the positions of the end portions of the coil positioned on the most downstream side in the heating length direction.

[0036] As described above, the volume of one core 1120 provided to the upper inductor 1100 is different between the heating upstream-side region of the one core 1120 and the heating downstream-side region of the one core 1120. In like manner, the volume of one core 1220 provided to the lower inductor 1200 is different between the heating upstream-side region of the one core 1220 and the heating downstream-side region of the one core 1220.

[0037] Here, the same main magnetic flux flows through one core 1120 provided to the upper inductor 1100. In like manner, the same main magnetic flux flows through one core 1220 provided to the lower inductor 1200. FIG. 5 is a view conceptually illustrating one example of the main magnetic flux that flows through the induction heating device 1000. Note that in FIG. 5, the configuration of the coils 1110, 1210 is illustrated in a simplified manner. Further, in FIG. 5, hatching indicating a cross section is omitted.

[0038] The main magnetic flux is a magnetic flux that contributes to heating of the conductor plate M. The main magnetic flux is a magnetic flux that passes through the conductor plate M, out of magnetic fluxes generated from the cores 1120, 1220. The main magnetic flux intersects substantially orthogonal (preferably orthogonal) to the plate surface of the conductor plate M. As illustrated in FIG. 5, magnetic flux lines 1 to 32 expressing the main magnetic flux respectively have the same starting point and end point. Specifically, as illustrated in FIG. 5, a path (magnetic path) configured by the individual magnetic flux lines 1 to 32 becomes a closed path. FIG. 5 exemplifies a case where the path (magnetic path) configured by the magnetic flux lines 1 to 32 is a closed path passing through the core 1120 provided to the upper inductor 1100, the conductor plate M, and the core 1220 provided to the lower inductor 1200.

[0039] In the upper inductor 1100, the same magnetic flux flows through the core 1120, Specifically, there exists, inside the core 1120, the path (magnetic path) configured by the same magnetic flux lines 1 to 32. Therefore, the core 1120 is one core. In like manner, in the lower inductor 1200, the same magnetic flux flows through the core 1220. Specifically, there exists, inside the core 1220, the path (magnetic path) configured by the same magnetic flux lines 1 to 32. Therefore, the core 1220 is one core. FIG. 1 to FIG. 4 exemplify a case where the cores 1120, 1220 are respectively configured in an integrated manner. It is assumed that a plurality of portions configuring a core are arranged in a state of having an interval therebetween. When the same main magnetic flux flows through the plurality of portions, the core configured by the plurality of portions is one core.

[0040] On the other hand, in the upper inductor 1100, a core through which the same main magnetic flux as such a main magnetic flux does not flow, is not the same core (specifically, a different core). In like manner, in the lower inductor 1200, a core through which the same main magnetic flux as such a main magnetic flux does not flow, is a different core. Further, even if the same main magnetic flux flows through the core 1120 provided to the upper inductor 1100 and the core 1220 provided to the lower inductor 1200, the cores are different cores.

[0041] As described above, FIG. 1 to FIG. 4 exemplify a case where the upper inductor 1100 has one core 1120. Further, FIG. 1 to FIG. 4 exemplify a case where the volume in the heating downstream-side region of the core 1120 is larger than the volume in the heating upstream-side region of the core 1120. In like manner, FIG. 1 to FIG. 4 exemplify a case where the lower inductor 1200 has one core 1220. Further, FIG. 1 to FIG. 4 exemplify a case where the volume in the heating downstream-side region of the core 1220 is larger than the volume in the heating upstream-side region of the core 1220. The reason why the volume in the heating downstream-side region of the cores 1120, 1220 is set to be larger than the volume in the heating upstream-side region of the cores 1120, 1220, is because a heating value of the conductor plate M (specifically, a heating amount with respect to the conductor plate M) that is passing through the heating downstream-side region is set to be larger than the heating value of the conductor plate M that is passing through the heating upstream-side region. In the explanation below, out of the heating upstream-side region and the heating downstream-side region, the region with smaller volume of the core will be referred to as a heating amount decreased region, according to need. Further, the region with larger volume of the core will be referred to as a heating amount increased region, according to need. FIG. 1 to FIG. 4 exemplify a case where the heating upstream-side region is the heating amount decreased region, and the heating downstream-side region is the heating amount increased region. This is why (heating amount decreased region) is described below the heating upstream-side region, and (heating amount increased region) is described below the heating downstream-side region in FIG. 1, FIG. 2A, and FIG. 2B.

[0042] In FIG. 1 to FIG. 4, a case is exemplified in which a region from the most upstream end position of coil MU to the reference position SP, in the region in the heating length direction (y-axis direction) of the induction heating device 1000, is the heating upstream-side region (heating amount decreased region). Further, in FIG. 1, FIG. 2A, and FIG. 2B, a case is exemplified in which a region from the reference position SP to a most downstream position CD, in the region in the heating length direction (y-axis direction) of the upper inductor 1100, is the heating downstream-side region (heating amount increased region). In like manner, in FIG. 1, FIG. 2A, and FIG. 2B, a case is exemplified in which a region from the reference position SP to the most downstream position CD, in the region in the heating length direction (y-axis direction) of the lower inductor 1200, is the heating downstream-side region (heating amount increased region). The most downstream position CD is a position of an end portion positioned on the most downstream side (y-axis positive direction side) in the heating length direction (y-axis direction), out of the end portions of the upper inductor 1100 and the lower inductor 1200.

[0043] On the contrary to the example illustrated in FIG. 1 to FIG. 4, in one core provided to the upper inductor, the volume in the heating upstream-side region may be larger than the volume in the heating downstream-side region. In like manner, in one core provided to the lower inductor, the volume in the heating upstream-side region may be larger than the volume in the heating downstream-side region. It is configured as above when the heating value of the conductor plate M (specifically, the heating amount with respect to the conductor plate M) that is passing through the heating upstream-side region is made to be larger than the heating value of the conductor plate M that is passing through the heating downstream-side region. In this case, the heating downstream-side region is the heating amount decreased region, and the heating upstream-side region is the heating amount increased region. For example, when the induction heating device 1000 illustrated in FIG. 1 to FIG. 4 is in a state of being rotated by 180, it is possible to realize one example of the induction heating device in which the volume of the core in the heating upstream-side region is larger than that in the heating downstream-side region. Therefore, an illustration of such an induction heating device will be omitted. Note that a position in the heating length direction (y-axis direction) of a rotation axis when rotating the induction heating device 1000 illustrated in FIG. 1 to FIG. 4 by 180 is, for example, the reference position SP. Further, a position in the width direction (x-axis direction) of the rotation axis is, for example, a center position of the cores 1120, 1220, and further, a direction in which the rotation axis extends is, for example, the plate thickness direction (z-axis direction).

[0044] The volumes of the cores 1120, 1220 are made to differ between the heating upstream-side region and the heating downstream-side region as described above. Therefore, the heating value of the conductor plate M (specifically, the heating amount with respect to the conductor plate M) that is passing through the heating downstream-side region and the heating value of the conductor plate M that is passing through the heating upstream-side region can be made to differ so as to satisfy the quality required of the conductor plate M. Accordingly, it is possible to improve the quality of the conductor plate M.

[0045] At which degree the heating value of the conductor plate M that is passing through the heating downstream-side region and the heating value of the conductor plate M that is passing through the heating upstream-side region should be differed to satisfy the quality required of the conductor plate M, is decided based on results of a simulation and a numerical analysis, for example. In the simulation, heating of the conductor plate M is performed by using an experimental device simulating induction heating of the conductor plate M, for example, From the conductor plate M after the heating, the quality of the conductor plate M can be checked. In the numerical analysis, a numerical simulation simulating the induction heating of the conductor plate M is performed, for example. In the numerical simulation, for example, at least one calculation out of a calculation of magnetic flux density inside and outside the conductor plate M, a calculation of magnetic property of the conductor plate M, and a calculation of crystal structure of the conductor plate M, is performed. From results of the numerical simulation, the quality of the conductor plate M can be checked.

[0046] Ratios of the volumes of the cores 1120, 1220 in the heating amount increased region to the volumes of the cores 1120, 1220 in the heating amount decreased region, are determined according to at which degree the heating value of the conductor plate M that is passing through the heating downstream-side region and the heating value of the conductor plate M that is passing through the heating upstream-side region should be differed. From a viewpoint of making the quality of the conductor plate M to be clearly differed between a case where there is such a difference and a case where there is no such a difference, the ratios of the volumes of the cores 1120, 1220 in the heating amount increased region to the volumes of the cores 1120, 1220 in the heating amount decreased region, are preferably 5.1 or more, respectively.

[0047] FIG. 1 to FIG. 4 exemplify a case where the cores 1120, 1220 have center-side leg portions 1121, 1221, center-side body portions 1122, 1222, end-side body portions 1123, 1223, and end-side leg portions 1124, 1224, respectively. Note that in FIG. 1 to FIG. 4, the center-side leg portions 1121, 1221, the center-side body portions 1122, 1222, the end-side body portions 1123, 1223, and the end-side leg portions 1124, 1224 are indicated by a two-dot chain line (a virtual line), for the convenience of notation and explanation.

[0048] The center-side leg portions 1121, 1221 are arranged in hollow regions of the coils 1110, 1210, respectively. FIG. 1 to FIG. 4 exemplify a case where the center-side leg portions 1121, 1221 are arranged so that center positions in the heating length direction (y-axis direction) of the center-side leg portions 1121, 1221 become the reference position SP. The end-side leg portions 1124, 1224 are arranged on the heating amount increased region side (y-axis positive direction side in FIG. 1 to FIG. 4) relative to the coils 1110, 1210, respectively. The center-side body portions 1122, 1222, and the end-side body portions 1123, 1223 are arranged on a back side relative to the coils 1110, 1210, respectively. The back side corresponds to an opposite side of the side where the conductor plate M exists (specifically, the side where the conductor plate M does not exist). The back side in the upper inductor 1100 corresponds to the side where the lower inductor 1200 does not exist. The back side in the lower inductor 1200 corresponds to the side where the upper inductor 1100 does not exist. In the example illustrated in FIG. 1 to FIG. 4, the back side relative to the coil 1110 corresponds to the z-axis positive direction side relative to the coil 1110, and the back side relative to the coil 1210 corresponds to the z-axis negative direction side relative to the coil 1210. The center-side body portions 1122, 1222 include regions on the heating amount increased region side (y-axis positive direction side in FIG. 1 to FIG. 4) relative to the center-side leg portions 1121, 1221, respectively. The end-side body portions 1123, 1223 are arranged on the heating amount increased region side relative to the center-side body portions 1122, 1222, and the coils 1110, 1210, respectively.

[0049] FIG. 1 to FIG. 4 exemplify a case where the center-side leg portions 1121, 1221, the center-side body portions 1122, 1222, the end-side body portions 1123, 1223, and the end-side leg portions 1124, 1224 have a rectangular parallelepiped shape. Further, FIG. 1 to FIG. 4 exemplify a case where lengths in the width direction (x-axis direction) of the center-side leg portions 1121, 1221, the center-side body portions 1122, 1222, the end-side body portions 1123, 1223, and the end-side leg portions 1124, 1224 are the same. Further, FIG. 1 to FIG. 4 exemplify a case where tip faces (end faces on the conductor plate M side) of the center-side leg portions 1121, 1221 are arranged on the conductor plate M side relative to the coils 1110, 1210. Further, FIG. 1 to FIG. 4 exemplify a case where the coils 1110, 1210 are arranged on the conductor plate M side relative to tip faces of the end-side leg portions 1124, 1224. Further, FIG. 1 to FIG. 4 exemplify a case where lengths in the plate thickness direction (z-axis direction) of the center-side body portions 1122, 1222 and the end-side body portions 1123, 1223 are the same. Further, FIG. 1 to FIG. 4 exemplify a case where the center-side body portion 1122 and the end-side body portion 1123 are magnetically connected to form one rectangular parallelepiped shape as a whole. In like manner, FIG. 1 to FIG. 4 exemplify a case where the center-side body portion 1222 and the end-side body portion 1223 are magnetically connected to form one rectangular parallelepiped shape as a whole. Note that when the portions are magnetically connected, this means that the same main magnetic flux flows through the portions as the main magnetic flux described above while referring to FIG. 5.

[0050] FIG. 1 to FIG. 4 exemplify a case where the center-side body portion 1122 is arranged on the back side relative to the center-side leg portion 1121. Concretely, FIG. 1 to FIG. 4 exemplify a case where a base end face (an end face on the opposite side of the conductor plate M side) of the center-side leg portion 1121 is connected to the center-side body portion 1122 in a seamless manner. Therefore, a main magnetic flux same as the main magnetic flux that flows through the center-side body portion 1122, flows through the center-side leg portion 1121. Further, FIG. 1 to FIG. 4 exemplify a case where the center-side body portion 1122 is arranged on the upstream side relative to the end-side body portion 1123. Concretely, FIG. 1 to FIG. 4 exemplify a case where an end face on the downstream side of the center-side body portion 1122 is connected to an end face on the upstream side of the end-side body portion 1123 in a seamless manner. Therefore, a main magnetic flux same as the main magnetic flux that flows through the end-side body portion 1123, flows through the center-side body portion 1122.

[0051] Further, FIG. 1 to FIG. 4 exemplify a case where the end-side body portion 1123 is arranged on the back side relative to the end-side leg portion 1124. Concretely, FIG. 1 to FIG. 4 exemplify a case where a base end face of the end-side leg portion 1124 is connected to the end-side body portion 1123 in a seamless manner. Therefore, a main magnetic flux same as the main magnetic flux that flows through the end-side leg portion 1124, flows through the end-side body portion 1123.

[0052] Further, FIG. 1 to FIG. 4 exemplify a case where a tip face of the center-side leg portion 1121 and a tip face of the end-side leg portion 1124 face the plate surface (the surface on the z-axis positive direction side) of the conductor plate M in a state of having an interval therebetween.

[0053] In like manner, a case is exemplified in which the center-side body portion 1222 is arranged on the back side relative to the center-side leg portion 1221. Concretely, FIG. 1 to FIG. 4 exemplify a case where a base end face (an end face on the opposite side of the conductor plate M side) of the center-side leg portion 1221 is connected to the center-side body portion 1222 in a seamless manner. Therefore, a main magnetic flux same as the main magnetic flux that flows through the center-side body portion 1222, flows through the center-side leg portion 1221. Further, FIG. 1 to FIG. 4 exemplify a case where the center-side body portion 1222 is arranged on the upstream side relative to the end-side body portion 1223. Concretely, FIG. 1 to FIG. 4 exemplify a case where an end face on the downstream side of the center-side body portion 1222 is connected to an end face on the upstream side of the end-side body portion 1223 in a seamless manner. Therefore, a main magnetic flux same as the main magnetic flux that flows through the end-side body portion 1223, flows through the center-side body portion 1222.

[0054] Further, FIG. 1 to FIG. 4 exemplify a case where the end-side body portion 1223 is arranged on the back side relative to the end-side leg portion 1224. Concretely, FIG. 1 to FIG. 4 exemplify a case where a base end face of the end-side leg portion 1224 is connected to the end-side body portion 1223 in a seamless manner. Therefore, a main magnetic flux same as the main magnetic flux that flows through the end-side leg portion 1224, flows through the end-side body portion 1223.

[0055] Further, FIG. 1 to FIG. 4 exemplify a case where a tip face of the center-side leg portion 1221 and a tip face of the end-side leg portion 1224 face the plate surface (the surface on the z-axis negative direction side) of the conductor plate M in a state of having an interval therebetween.

[0056] Further, FIG. 1 to FIG. 4 exemplify a case where positions of end portions in the width direction (x-axis direction) of the center-side leg portions 1121, 1221, the center-side body portions 1122, 1222, the end-side body portions 1123, 1223, and the end-side leg portions 1124, 1224 are respectively aligned. Specifically, FIG. 1 to FIG. 4 exemplify a case where the positions of the end portions on the x-axis positive direction side of the center-side leg portions 1121, 1221, the center-side body portions 1122, 1222, the end-side body portions 1123, 1223, and the end-side leg portions 1124, 1224 are respectively the same. Further, FIG. 1 to FIG. 4 exemplify a case where the positions of the end portions on the x-axis negative direction side of the center-side leg portions 1121, 1221, the center-side body portions 1122, 1222, the end-side body portions 1123, 1223, and the end-side leg portions 1124, 1224 are respectively the same.

[0057] Further, FIG. 1 to FIG. 4 exemplify a case where there exists no portion of the cores 1120, 1220 except for the center-side leg portions 1121, 1221, and the center-side body portions 1122, 1222, in the heating amount decreased region.

[0058] Note that here, for the convenience of explanation, the configuration of the cores 1120, 1220 has been explained while dividing it into the center-side leg portions 1121, 1221, the center-side body portions 1122, 1222, the end-side body portions 1123, 1223, and the end-side leg portions 1124, 1224, respectively. However, the center-side leg portions 1121, 1221, the center-side body portions 1122, 1222, the end-side body portions 1123, 1223, and the end-side leg portions 1124, 1224, are integrated, respectively. Therefore, there is no boundary line at boundaries among the center-side leg portions 1121, 1221, the center-side body portions 1122, 1222, the end-side body portions 1123, 1223, and the end-side leg portions 1124, 1224. However, it is also possible that they are manufactured as separate portions and combined, to thereby configure one core. For example, at least two portions out of the center-side leg portion 1121, the center-side body portion 1122, the end-side body portion 1123, and the end-side leg portion 1124 may be arranged in a state of having an interval therebetween. However, the at least two portions are configured and arranged so that the same main magnetic flux flows through the at least two portions. In like manner, at least two portions out of the center-side leg portion 1221, the center-side body portion 1222, the end-side body portions 1123, 1223, and the end-side leg portion 1224 may be arranged in a state of having an interval therebetween. However, the at least two portions are configured and arranged so that the same main magnetic flux flows through the at least two portions.

[0059] Further, the induction heating device 1000 of the present embodiment has leakage flux reducing members 1140, 1240. The leakage flux reducing members 1140, 1240 are respectively arranged to reduce leakage of magnetic flux generated when the cores 1120, 1220 are excited by the alternating currents that flow through the coils 1110, 1210. The leakage flux is a magnetic flux that does not contribute to the heating of the conductor plate M. The leakage flux is a magnetic flux that does not pass through the conductor plate M, out of magnetic fluxes generated from the cores 1120, 1220.

[0060] The leakage flux reducing members 1140, 1240 are arranged in the heating amount decreased region. FIG. 1 to FIG. 4 exemplify a case where the leakage flux reducing members 1140, 1240 are arranged to face end faces on the back side of the coils 1110, 1210, in a state of having an interval therebetween. Further, the present embodiment exemplifies a case where the leakage flux reducing member is not arranged in the heating amount increased region. However, the leakage flux reducing member may also be arranged in the heating amount increased region.

[0061] Further, FIG. 1 to FIG. 4 exemplify a case where each of the leakage flux reducing members 1140, 1240 is one piece of plate. Further, FIG. 1 to FIG. 4 exemplify a case where lengths in the width direction (x-axis direction) of the leakage flux reducing members 1140, 1240 are the same as the lengths in the width direction of the cores 1120, 1220, respectively. Further, FIG. 1 to FIG. 4 exemplify a case where lengths in the heating length direction (y-axis direction) of the leakage flux reducing members 1140, 1240 have values obtained by subtracting the lengths in the heating length direction of the center-side leg portions 1121, 1221 from the lengths in the heating length direction of the center-side body portions 1122, 1222, respectively. Further, FIG. 1 to FIG. 4 exemplify a case where positions of surfaces on the back side of the leakage flux reducing members 1140, 1240, and the positions of the surfaces on the back side of the cores 1120, 1220 are aligned (the positions in the z-axis direction of the surfaces are the same), respectively. Further, FIG. 1 to FIG. 4 exemplify a case where positions of end portions in the width direction (x-axis direction) of the leakage flux reducing members 1140, 1240, and the positions of the end portions in the width direction of the cores 1120, 1220 are respectively aligned (the positions of the end portions in the x-axis positive direction side, and the positions of the end portions in the x-axis negative direction side are respectively the same). Further, FIG. 1 to FIG. 4 exemplify a case where a plate surface of the plate configuring each of the leakage flux reducing members 1140, 1240 is substantially parallel (preferably parallel) to the plate surface of the conductor plate M.

[0062] From a viewpoint of reducing the leakage of magnetic flux generated when the cores 1120, 1220 are excited by the alternating current that flows through the coil 1110, the leakage flux reducing members 1140, 1240 are preferably configured by using a non-magnetic material. Further, from a viewpoint of suppressing heat generation of the induction heating device 1000, the leakage flux reducing members 1140, 1240 are more preferably configured by using copper with high heat conductivity. The present embodiment exemplifies a case where each of the leakage flux reducing members 1140, 1240 has one piece of copper plate. Note that the leakage flux reducing members 1140, 1240 may also be configured by using a plurality of pieces of copper plate stacked so that plate surfaces thereof face each other, for example.

[0063] Further, the induction heating device 1000 of the present embodiment has interposed members 1130, 1230. The interposed members 1130, 1230 are respectively used for performing positioning of the leakage flux reducing members 1140, 1240, securement of electric insulation between the coils 1110, 1210 and the leakage flux reducing members 1140, 1240, and the like. The interposed members 1130, 1230 are respectively arranged between the leakage flux . . . reducing members 1140, 1240, and the coils 1110, 1210, From a viewpoint of securing the electric insulation between the coils 1110, 1210, and the leakage flux reducing members 1140, 1240, and reducing the soft magnetic material in the heating amount decreased region, the interposed members 1130, 1230 are preferably configured by using a resinous material. The resinous material is, for example, a glass epoxy resin or a phenol resin. FIG. 1 to FIG. 4 exemplify a case where the interposed members 1130, 1230 have a rectangular parallelepiped shape having a size same as a space between the leakage flux reducing members 1140, 1240 and the coils 1110, 1210.

[0064] As illustrated in FIG. 1, in the induction heating device 1000 of the present embodiment, the cores 1120, 1220 do not exist on the upstream side (y-axis negative direction side) relative to the center-side leg portions 1121, 1221, respectively. Therefore, if the leakage flux reducing members 1140, 1240 do not exist, magnetic fluxes emitted from the cores 1120, 1220 toward the downstream side (y-axis negative direction side) relative to the cores 1120, 1220, are likely to become leakage fluxes that do not pass through the conductor plate M, for example. On the contrary, by arranging the leakage flux reducing members 1140, 1240, the magnetic fluxes emitted from the cores 1120, 1220 toward the downstream side (y-axis negative direction side) relative to the cores 1120, 1220, are likely to be directed in the direction of the conductor plate M, when compared to a case where the leakage flux reducing members 1140, 1240 are not arranged (refer to magnetic flux lines 19, 21, 23, 25, 27, 29, 31 illustrated in FIG. 5). Therefore, these magnetic fluxes are difficult to become leakage fluxes (specifically, they are likely to become main magnetic fluxes).

[0065] Note that the induction heating device 1000 may also have a not-illustrated shield plate for preventing overheating of the edge portion (the end portion in the width direction) of the conductor plate M. For example, the shield plates are arranged between the edge portion of the conductor plate M, and the cores 1120, 1220, respectively. Further, the shield plate may also move in accordance with the width of the conductor plate M and a meandering amount (a movement amount in the width direction) of the conductor plate M. Note that the shield plate is used for suppressing the passage of the main magnetic flux through the edge portion of the conductor plate M, and is not used for reducing the leakage flux.

[0066] FIG. 6A is a view conceptually illustrating one example a heating value of the conductor plate M that is heated by using the induction heating device 1000 of the present embodiment. FIG. 6B is a view conceptually illustrating one example of a heating value of the conductor plate M that is heated by using two general induction heating devices, as induction heating devices. The two general induction heating devices are arranged in a state of having an interval therebetween in the heating length direction (x-axis direction).

[0067] In FIG. 6A, P.sub.min is a minimum value of the heating value at a certain portion of the conductor plate M that is passing through the induction heating device 1000. The portion is, for example, a center portion in the width direction (x-axis direction). As illustrated in FIG. 6A, the heating value at each portion of the conductor plate M that is passing through the induction heating device 1000 of the present embodiment, becomes the minimum at the most upstream end position of coil MU. P.sub.max is a maximum value of the heating value at a certain portion of the conductor plate M that is passing through the induction heating device 1000. As illustrated in FIG. 6A, the heating value at each portion of the conductor plate M that is passing through the induction heating device 1000 of the present embodiment, becomes the maximum at the most downstream position CD. Further, in FIG. 6A, P.sub.A, P.sub.B are heating values at certain portions of the conductor plate M that is passing though the center-side leg portions 1121, 1221 provided to the induction heating device 1000.

[0068] As described above, in the induction heating device 1000 of the present embodiment, in one core 1120, 1220, the volume in the heating upstream-side region and the volume in the heating downstream-side region are made to differ. By adjusting the volume in the heating upstream-side region and the volume in the heating downstream-side region, the heating values at respective portions of the conductor plate M that is passing through the center-side leg portions 1121, 1221 provided to the induction heating device 1000 can be adjusted to the heating values P.sub.A, P.sub.B, and the like (this is indicated by a two-headed arrow line illustrated in FIG. 6A). Therefore, it is possible to make the heating value of the conductor plate M (specifically, the heating amount with respect to the conductor plate M) on the downstream side relative to the reference position SP, and the heating value of the conductor plate M on the upstream side relative to the reference position SP, to be differed from each other. Accordingly, it is possible to make a temperature increasing rate in the heating length direction (y-axis direction) in the region on the upstream side relative to the reference position SP, and a temperature increasing rate in the heating length direction in the region on the downstream side relative to the reference position SP, to be differed from each other, in one core 1120, 1220. From the above, it is possible to adjust the quality of the conductor plate M by adjusting the volume in the heating upstream-side region and the volume in the heating downstream-side region.

[0069] In FIG. 6B, CU1 expresses the most upstream position of the induction heating device arranged on the upstream side, out of the two general induction heating devices. The most upstream position is a position of an end portion positioned on the most upstream side (y-axis negative direction side) in the heating length direction (y-axis direction) out of end portions of an upper inductor and a lower inductor. Note that in the induction heating device 1000 of the present embodiment, a case is exemplified in which the most upstream end position of coil MU and the most upstream position are the same position.

[0070] MU1 expresses the most upstream end position of coil of the induction heating device arranged on the upstream side. SP1 expresses a reference position of the induction heating device arranged on the upstream side. MD1 expresses the most downstream end position of coil of the induction heating device arranged on the upstream side. CD1 expresses the most downstream position of the induction heating device arranged on the upstream side.

[0071] P.sub.1min is a minimum value of a heating value at a certain portion of the conductor plate M that is passing through the induction heating device arranged on the upstream side, out of the two general induction heating devices. As illustrated in FIG. 6B, the heating value at each portion of the conductor plate M that is passing through the induction heating device arranged on the upstream side, becomes the minimum at the most upstream position of coil CU1. P.sub.1max is a maximum value of a heating value at a certain portion of the conductor plate M that is passing through the induction heating device arranged on the upstream side. As illustrated in FIG. 6B, the heating value at each portion of the conductor plate M that is passing through the induction heating device arranged on the upstream side, becomes the maximum at the most downstream position CD1. Further, in FIG. 6B, P.sub.1c is a heating value at a certain portion of the conductor plate M that is passing through a center-side leg portion provided to the induction heating device arranged on the upstream side.

[0072] In the general induction heating device, the volume of one core is the same between the heating upstream-side region and the heating downstream-side region. Therefore, the heating value P.sub.1c at each portion of the conductor plate M that is passing through the center-side leg portion provided to the induction heating device arranged on the upstream side, out of the two general induction heating devices, is fixed to times the maximum value P.sub.1max of the heating value at the corresponding portion of the conductor plate M that is passing through the induction heating device arranged on the upstream side.

[0073] Further, in FIG. 6B, CU2 expresses the most upstream position of the induction heating device arranged on the downstream side, out of the two general induction heating devices. MU2 expresses the most upstream end position of coil of the induction heating device arranged on the downstream side. SP2 expresses a reference position of the induction heating device arranged on the downstream side. MD2 expresses the most downstream end position of coil of the induction heating device arranged on the downstream side. CD2 expresses the most downstream position of the induction heating device arranged on the upstream side.

[0074] P.sub.2min is a minimum value of a heating value at a certain portion of the conductor plate M that is passing through the induction heating device arranged on the downstream side, out of the two general induction heating devices. As illustrated in FIG. 6B, the heating value at each portion of the conductor plate M that is passing through the induction heating device arranged on the downstream side, becomes the minimum at the most upstream position of coil CU2. P.sub.2max is a maximum value of a heating value at a certain portion of the conductor plate M that is passing through the induction heating device arranged on the downstream side. As illustrated in FIG. 6B, the heating value at each portion of the conductor plate M that is passing through the induction heating device arranged on the downstream side, becomes the maximum at the most downstream position CD2. Further, in FIG. 6B, P.sub.2c is a heating value at a certain portion of the conductor plate M that is passing through a center-side leg portion provided to the induction heating device arranged on the downstream side.

[0075] As described above, in the general induction heating device, the volume of one core is the same between the heating upstream-side region and the heating downstream-side region. Therefore, the heating value P.sub.2c at each portion of the conductor plate M that is passing through the center-side leg portion provided to the induction heating device arranged on the downstream side, out of the two general induction heating devices, is fixed to times the maximum value P.sub.2max of the heating value at the corresponding portion of the conductor plate M that is passing through the induction heating device arranged on the downstream side.

[0076] In each of the induction heating devices described in Patent Literatures 1 to 3, the volume of one core is the same between the heating upstream-side region and the heating downstream-side region. Therefore, it is only possible to make the heating value of the conductor plate M (specifically, the heating amount with respect to the conductor plate M) on the upstream side relative to the reference positions SP1, SP2, and the heating value of the conductor plate M on the downstream side relative to the reference positions SP1, SP2 to be the same. Further, it is not possible to adjust the heating value of the conductor plate M in the heating length direction (y-axis direction) without using a plurality of induction heating devices. Specifically, it is not possible to adjust the heating value of the conductor plate M in the heating length direction (y-axis direction) without using a plurality of cores as the cores provided to the upper inductor. In like manner, it is not possible to adjust the heating value of the conductor plate M in the heating length direction (y-axis direction) without using a plurality of cores as the cores provided to the lower inductor. Therefore, a period of time for which the conductor plate M is heated by the induction heating device becomes long, when compared to the induction heating device 1000 of the present embodiment. Further, as illustrated in FIG. 6B, there is generated a region, between the two induction heating devices, in which the conductor plate M is not heated. Accordingly, there is a possibility that a temperature of the conductor plate M is lowered when the conductor plate M is being conveyed between the two induction heating devices. Based on the above, there is a possibility that the quality required as the quality of the conductor plate M cannot be satisfied, and besides, the following demerits may be generated, for example. Specifically, a large space has to be secured for installing the induction heating devices. Further, a cost is increased due to the installation of a plurality of induction heating devices.

(Design Method)

[0077] Next, an explanation will be made on one example of a design method of dimensions of the cores 1120, 1220 for configuring the induction heating device so as to be able to perform induction heating on the conductor plate to satisfy the quality required of the conductor plate. Here, the design method of dimensions of the cores 1120, 1220 in a case where the heating upstream-side region is the heating amount decreased region, and the heating downstream-side region is the heating amount increased region, will be exemplified.

[0078] A length (mm) in the heating length direction (y-axis direction) of each of the leakage flux reducing members 1140, 1240 is set to W.sub.1. A length (mm) in the heating length direction (y-axis direction) of each of the center-side body portions 1122, 1222 is set to W.sub.2 (>W.sub.1). A length (mm) in the heating length direction (y-axis direction) of each of the end-side body portions 1123, 1223 is set to W.sub.3. A length (mm) in the plate thickness direction (z-axis direction) of each of the end-side leg portions 1124, 1224 is set to W.sub.4. A length (mm) in the plate thickness direction (z-axis direction) of each of regions of the center-side leg portions 1121, 1221 projecting toward the conductor plate M side relative to the tip faces of the coils 1110, 1210 is set to W.sub.5. Note that W.sub.1 to W.sub.5 illustrated in FIG. 1 to FIG. 4 express these lengths.

[0079] Further, in a case where an attention is focused on a certain portion region of the conductor plate M, a heating value ratio (%) of the portion is set to P (P.sub.1 to P.sub.4). The heating value ratio P of a certain portion of the conductor plate M is one expressing, on percentage, a ratio of a heating value in the heating upstream-side region when the portion is passing through the region to a heating value of the portion when it is passing through the induction heating device 1000 (the heating upstream-side region and the heating downstream-side region). Note that in the example illustrated in FIG. 6A, the heating value ratio P is expressed by P.sub.AP.sub.max100 and P.sub.BP.sub.max100.

[0080] The present inventors performed a numerical analysis on the induction heating device by configuring cores while making combinations of numerical values of W.sub.1 to W.sub.5 to be differed, and calculated the heating value ratio P in each of the combinations. Note that conditions other than the numerical values of W.sub.1 to W.sub.5 are set to be the same. Further, numerical values given as respective symbols P.sub.1 to P.sub.4, W.sub.1 to W.sub.5 in the notation of mathematical formulas below are assumed to be 0 (zero) or positive values, Therefore, for example, W.sub.1 becomes 0 (zero) or a negative value.

[0081] First, P.sub.1 being the heating value ratio P in a case of making only W.sub.1 and W.sub.2 to be differed was calculated through the numerical analysis. Note that when changing W.sub.1 and W.sub.2, it was set to satisfy the condition of W.sub.2>W.sub.1. Further, when W.sub.1+W.sub.2 is set to a constant value and then W.sub.1 is made to be shorter than that in a state illustrated in FIG. 1, W.sub.2 was made to be long by assuming that a part of region on the heating amount increased region side (y-axis positive direction side in FIG. 1) out of the regions of the interposed members 1130, 1230 and the leakage flux reducing members 1140, 1240 illustrated in FIG. 1, is the region of the core 1120. Specifically, the center-side body portions 1122, 1222 were extended toward the heating amount decreased region side (y-axis negative direction side in FIG. 1). However, the most upstream end position of coil MU is not changed. Further, from the result of the numerical analysis, a regression formula (regression coefficient and constant) expressing a relation between P.sub.1, and W.sub.1 and W.sub.2, was calculated through a regression analysis. As a result of this, it was possible to favorably reproduce the result of numerical analysis by setting P.sub.1 to a function of W.sub.1/(W.sub.1+W.sub.2), as in the following formula (1). In the formula (1), P.sub.1 becomes smaller as W.sub.1 increases. Note that the formula (1) is a simple regression formula in which W.sub.1/(W.sub.1+W.sub.2) is set to an explanatory variable.

[00001]$\begin{array}{cc}\left[\mathrm{Mathematical}\mathrm{formula}1\right]& \\ P_1=f\left(\frac{W_1}{W_1+W_2}\right)& \left(1\right)\end{array}$

[0082] Next, P.sub.2 being the heating value ratio P in a case of making not only W.sub.1 and W.sub.2 but also W.sub.3 to be differed was calculated through the numerical analysis. Further, from the result of the numerical analysis, a regression formula including P.sub.1 of the formula (1) was calculated through the regression analysis, as a regression formula expressing a relation between P.sub.2, and W.sub.1, W.sub.2, and W.sub.3. As a result of this, it was possible to favorably reproduce the result of numerical analysis by expressing P.sub.2 by a formula in which a function f (W.sub.3/(W.sub.2+W.sub.3) of W.sub.3/(W.sub.2+W.sub.3) is subtracted from P.sub.1, as in the following formula (2). In the formula (2), P.sub.2 becomes smaller as W.sub.3 increases. The function f (W.sub.3/(W.sub.2+W.sub.3) of the right side of the formula (2) indicates that, when the end-side body portions 1123, 1223 exist, each region of the conductor plate M further generates heat by a value of the function f (W.sub.3/W.sub.2+W.sub.3) in the heating downstream-side region (heating amount increased region), when compared to a case where the end-side body portions 1123, 1223 do not exist. Note that the formula (2) is a multiple regression formula in which W.sub.1/(W.sub.1+W.sub.2) and W.sub.3/(W.sub.2+W.sub.3) are set to explanatory variables.

[00002]$\begin{array}{cc}\left[\mathrm{Mathematical}\mathrm{formula}2\right]& \\ P_2=P_1-f\left(\frac{W_3}{W_2+W_3}\right)& \left(2\right)\end{array}$

[0083] Next, P4 being the heating value ratio P in a case of making not only W.sub.1, W.sub.2, and W.sub.3 but also W.sub.4 to be differed was calculated through the numerical analysis. Further, from the result of the numerical analysis, a regression formula including P.sub.2 of the formula (2) was calculated through the regression analysis, as a regression formula expressing a relation between P4, and W.sub.1, W.sub.2, W.sub.3, and W.sub.4. As a result of this, it was possible to favorably reproduce the result of numerical analysis by expressing P.sub.3 by a formula in which a function f (W.sub.4) of W.sub.4 is subtracted from P.sub.2, as in the following formula (3). In the formula (3), P.sub.3 becomes smaller as W.sub.4 increases. The function f (W.sub.4) of the right side of the formula (3) indicates that, when the end-side leg portions 1124, 1224 exist, each region of the conductor plate M further generates heat by f (W.sub.4) in the heating downstream-side region (heating amount increased region), when compared to a case where the end-side leg portions 1124, 1224 do not exist. Note that the formula (3) is a multiple regression formula in which W.sub.1/(W.sub.1+W.sub.2), W.sub.3/(W.sub.2+W.sub.5), and W.sub.4 are set to explanatory variables.

[00003]$\begin{array}{cc}\left[\mathrm{Mathematical}\mathrm{formula}3\right]& \\ P_3=P_2-f\left(W_4\right)& \left(3\right)\end{array}$

[0084] At last, the heating value ratio P.sub.A in a case of making W.sub.1, W.sub.2, W.sub.3, W.sub.4, and W.sub.5 to be differed was calculated through the numerical analysis. Further, from the result of the numerical analysis, a regression formula including P.sub.3 of the formula (3) was calculated through the regression analysis, as a regression formula expressing a relation between P, and W.sub.1, W.sub.2, W.sub.3, W.sub.4, and W.sub.5. As a result of this, it was possible to favorably reproduce the result of numerical analysis by expressing P.sub.4 by a formula in which a function f (W.sub.5) of W.sub.5 is added to P.sub.3, as in the following formula (4). In the formula (4), P.sub.4 becomes larger as W.sub.5 increases. The function f (W.sub.5) of the right side of the formula (4) indicates that, when the center-side leg portions 1121, 1221 project toward the conductor plate M side relative to the tip faces of the coils 1110, 1210, each region of the conductor plate M further generates heat by f (W.sub.5) in the heating upstream-side region (heating amount decreased region), when compared to a case where the center-side leg portions do not project toward the conductor plate M side relative to the tip faces of the coils. Note that the formula (4) is a multiple regression formula in which W.sub.1 (W.sub.1+W.sub.2), W.sub.3/(W.sub.2+W.sub.3), W.sub.4, and W.sub.5 are set to explanatory variables,

[00004]$\begin{array}{cc}\left[\mathrm{Mathematical}\mathrm{formula}4\right]& \\ P_4=P_3+f\left(W_5\right)& \left(4\right)\end{array}$

[0085] If P.sub.4 is determined based on the quality required of the conductor plate M being the heating target, and W.sub.1, W.sub.2, W.sub.3, W.sub.4, and W.sub.5 are selected so as to satisfy the formula (1) to the formula (4), it is possible to design W.sub.1, W.sub.2, W.sub.3, W.sub.4, and W.sub.5. At least one of W.sub.1, W.sub.3, W.sub.4, and W.sub.5 may also be 0 (zero). When W.sub.1 is 0 (zero), this means that the interposed members 1130, 1230, and the leakage flux reducing members 1140, 1240 are not arranged. When W.sub.3 is 0 (zero); this means that the end-side body portions 1123, 1223, and the end-side leg portions 1124, 1224 are not arranged. When W.sub.4 is 0 (zero), this means that the end-side leg portions 1124, 1224 are not arranged. On the other hand, W.sub.2 never becomes 0 (zero).

[0086] As described above, P.sub.4 is decided based on the results of the simulation and the numerical analysis, for example. When performing the simulation, for example, the conductor plate is subjected to induction heating or heating by another method by making an input heat amount in a region corresponding to the heating amount decreased region and an input heat amount in a region corresponding to the heating amount increased region to be differed. It is checked whether or not the quality required of the conductor plate is satisfied, by checking the quality of the conductor plate after being heated. In such a case, P.sub.4 is decided by using the input heat amount when the quality required of the conductor plate is satisfied. Further, when performing the numerical analysis, a crystal structure and a magnetic property of the conductor plate when performing induction heating on the conductor plate by making an input heat amount in a region corresponding to the heating amount decreased region and an input heat amount in a region corresponding to the heating amount increased region to be differed, are calculated, for example. Note that in the numerical analysis, evaluation indices of the crystal structure and the magnetic property of the conductor plate may also be calculated. In such a case, when the calculated result satisfies the quality required of the conductor plate, the input heat amount at that time is used to decide P.sub.4.

OTHER EMBODIMENTS

[0087] It should be noted that the above explained embodiments of the present invention merely illustrate concrete examples of implementing the present invention, and the technical scope of the present invention is not to be construed in a restrictive manner by these embodiments. That is, the present invention may be implemented in various forms without departing from the technical spirit or main features thereof.

INDUSTRIAL APPLICABILITY

[0088] The present invention can be utilized for heating a conductor plate, for example.