Patent Grant
10563282
The present invention relates to an induction heating device for a metal strip.
When heating a metal strip in a heat treatment furnace, heating is generally performed indirectly using radiant tubes. In such indirect heating, thermal inertia is high, such that effective heat input to the metal strip becomes more difficult the smaller the difference between the temperature of the metal strip and the furnace temperature, resulting in productivity constraints. Moreover, in such indirect heating, it is difficult to achieve rapid heating in the vicinity of a transformation point at which a heat absorbing reaction occurs, and it is also difficult to achieve high temperature annealing due to constraints in the heat resistance of the radiant tubes. The degree of freedom when selecting heat treatment conditions for metal strips is therefore constrained.
By contrast, in induction heating, the metal strip is heated using high frequency current, and the heating speed and heating temperature can be freely controlled. Induction heating consequently offers a high degree of freedom in heat treatment operations and in the development of metal strip products, and is a heating method that has been garnering attention in recent years.
There are two main methods of induction heating. One method is a longitudinal magnetic flux (LF) heating method in which a high frequency current is passed through an induction coil surrounding the periphery of a metal strip, causing magnetic flux to penetrate a length direction (direction of progress) cross-section of the metal strip (a cross-section taken orthogonally to the length direction of the metal strip). This generates an induction current perpendicular to the magnetic flux and running in a loop within the length direction (direction of progress) cross-section of the metal strip, thereby heating the metal strip.
The other method is a transverse magnetic flux (TF) heating method in which inductors (strong magnets) wound with primary coils are placed on both sides of the metal strip, and current is passed through the primary coils to generate magnetic flux that penetrates a strip face of the metal strip via the inductors, generating an induction current in the strip face of the metal strip, and thereby heating the metal strip.
In LF induction heating, in which induction current runs in a loop within the length direction (direction of progress) cross-section of the metal strip, due to the relationship between the permeation depth δ of the current and the current frequency f (δ (mm)=5.03×105√(ρ/μr·f), wherein ρ (Ωm): specific resistance, μr: specific magnetic permeability, f: frequency (Hz)), if the permeation depths of induction currents generated at front and back faces of the metal strip are greater than the thickness of a steel sheet, the generated induction currents interfere with each other, with the result that induction current is not generated within the length direction (direction of progress) cross-section of the metal strip.
For example, in the case of non-magnetic metal strips, steel sheets that lose their magnetism on exceeding their Curie temperature, or the like, the current permeation depth δ becomes deep, and so induction current is not generated if the strip thickness of the metal strip is thin. Moreover, even in the case of magnetic metal strips, for example, if the strip thickness is too thin in comparison to the permeation depth, induction current is not generated within the length direction (direction of progress) cross-section of the metal strip when using the LF method.
By contrast, in TF induction heating, since the magnetic flux penetrates the sheet faces of the metal strip, the metal strip can be heated irrespective of the strip thickness, and whether or not the metal strip is magnetic or non-magnetic. However, there is an issue with TF induction heating in that overheating is liable to occur at ends of the metal strip (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2002-151245).
In normal TF induction heating, there is also an issue that it is difficult to adapt to changes in the strip width of the metal strip, since it is not easy to change the shape of the inductors facing the strip faces of the metal strip.
Accordingly, for example, Japanese Patent Application Publication (JP-B) No. S63-027836 describes an electromagnetic induction heater provided with magnetic pole segments that are disposed side-by-side in a width direction of a thin sheet so as to face the sheet faces of the thin sheet, and are capable of moving independently in a strip thickness direction of the thin sheet, and a movable shielding plate of a non-magnetic metal, that is capable of deployment in the sheet width direction of the thin sheet and that adjusts the magnetic field of the magnetic pole segments.
This electromagnetic induction heater is capable of adjusting the magnetic flux according to changes in the sheet width of the thin sheet. However, it is difficult to adjust the magnetic flux in the sheet width direction rapidly when there is a large change in the sheet width of the thin sheet.
Japanese National Phase Publication No. H11-500262 describes a transverse magnetic flux induction heating system provided with plural independent magnetic rods, and a variable width magnetic circuit capable of adapting to the strip width of a metal strip. However, in this induction heating system, induction coils are integrated together with the magnetic rods, and so it is difficult to adjust the magnetic flux in the strip width direction if the strip width of the metal strip exceeds the induction coils. Moreover, it is difficult to adjust the magnetic flux in the strip width direction if the strip width of the metal strip is less than the sum of the width of the magnetic rods.
Moreover, JP-A No. 2002-8838 describes an induction heating device including plural magnetic rods. In this induction heating device, the plural magnetic rods are configured so as to be capable of moving in the strip width direction of a metal strip. This thereby enables changes in the strip width dimension of the metal strip to be accommodated by adjusting the spacing of the plural magnetic rods. However, in this induction heating device, the number of the magnetic rods disposed facing the metal strip is fixed even when metal strips have different width dimensions. Metal strips with different width dimensions are accommodated solely by adjusting the spacing of the magnetic rods. The following issue is therefore conceivable. Namely, when heating a metal strip having a broad strip width, the number of the magnetic rods facing the metal strip is fixed, and when there is a large change in the strip width of the metal strip, the spacing of the magnetic rods becomes larger. In other words, a gap between the magnetic rods in the strip width direction of the metal strip becomes larger. Since no magnetic rods are disposed in this gap area, there is a tendency for the heating temperature to decrease at a portion of the metal strip corresponding to the gap. As a result, there is a possibility of the heating temperature becoming uneven in the strip width direction of the metal strip.
In consideration of the above circumstances, an object of the present invention is to provide an induction heating device for a metal strip that is capable of achieving a uniform heating temperature in a strip width direction of a metal strip, even when there is a large change in the strip width of the metal strip.
An induction heating device of the present disclosure includes: an induction coil that is provided on one strip thickness direction side or on both strip thickness direction sides of a metal strip that travels along a length direction thereof, and that induces an induction current in the metal strip when a primary current is passed through the induction coil, the induction current configuring a closed loop as viewed from the strip thickness direction of the metal strip; plural magnetic cores that face the metal strip in the strip thickness direction and that are disposed at a specific position separated from the metal strip by a specific distance so as to concentrate magnetic flux generated by the induction coil; and a moving mechanism that is coupled to the magnetic cores, and that moves the magnetic cores so as to increase or decrease a disposed number of the magnetic cores at the specific position disposed side-by-side along a strip width direction of the metal strip.
In the metal strip induction heating device configured as described above, the induction coil is provided on one strip thickness direction side or on both strip thickness direction sides of the metal strip that travels along its length direction. The induction current configuring a closed loop as viewed from the strip thickness direction of the metal strip is induced in the metal strip when the primary current is passed through the induction coil.
The magnetic cores are disposed facing the metal strip in the strip thickness direction, and are the magnetic cores are disposed at the specific position separated from the metal strip by a specific distance, such that magnetic flux generated by the induction coil is concentrated by the magnetic cores.
Note that the moving mechanism is coupled to the magnetic cores. The moving mechanism moves the magnetic cores so as to increase or decrease the disposed number of the magnetic cores at the specific position disposed side-by-side along the strip width direction of the metal strip.
Accordingly, when continuously heating the metal strip by induction heating, a number of the magnetic cores corresponding to the strip width of the metal strip can be disposed at the specific position even if the strip width of the metal strip changes. Namely, when heating a metal strip having a broad strip width, the disposed number of the magnetic cores disposed at the specific position can be increased in comparison to when heating a metal strip having a narrow strip width. Accordingly, the spacing in the strip width direction of the metal strip of the magnetic cores disposed at the specific position can be suppressed from becoming large, even when heating a metal strip having a broad strip width. This thereby enables a more uniform heating temperature to be achieved over the strip width direction of the metal strip.
The induction heating device for a metal strip of the present disclosure enables a uniform heating temperature to be achieved over the strip width direction of the metal strip, even when there is a large change in the strip width of the metal strip.
Explanation follows regarding a metal strip induction heating device 10 (referred to below as simply the “induction heating device 10”) according to a first exemplary embodiment of the present invention, with reference to
In the following explanation, a strip thickness direction of the metal strip 40 is taken as an up-down direction of the induction heating device 10. A front face side of the metal strip 40 (the arrow A direction side in
The induction coils 12 are configured from a conductor such as copper, and are provided at a separation toward the upper side of the metal strip 40. Note that each induction coil 12 may be configured from a single conductor, or may be configured from plural conductors. Moreover, as illustrated in
The pair of straight portions 16 are disposed side-by-side in the length direction of the metal strip 40. Moreover, as illustrated in
The plural magnetic cores 20 are disposed on the opposite side from the metal strip 40 with respect to the straight portions 16 of the induction coils 12 (namely on the upper side). Each of the magnetic cores 20 is configured from a ferromagnetic core, and is, for example, configured from ferrite, layered electromagnetic steel plates, amorphous alloys, or the like. Note that the magnetic cores 20 may have an appropriately selected design according to the heating ability given to the induction heating device 10, in order to avoid magnetic flux saturation. Moreover, if there is a concern that the magnetic cores 20 will generate heat, it is desirable to cool the magnetic cores 20 with a cooling system using water-cooled copper plates or the like.
Each magnetic core 20 is formed in a rectangular block shape. A width dimension (length in the strip width direction of the metal strip 40), height dimension (length in the up-down direction), and depth dimension (length in the length direction of the metal strip 40) of the magnetic cores 20 are set as appropriate based on the shape and length of the induction coils 12. Note that the shape of the magnetic cores 20 is not limited to a rectangular block shape. The magnetic cores 20 are coupled to the moving mechanism 30, described later, and are disposed side-by-side at a specific spacing din the strip width direction of the metal strip 40 at the upper side of the straight portions 16 of the induction coils 12. Namely, as illustrated in
Explanation follows regarding magnetic flux generated by the induction coils 12. As illustrated in
The magnetic flux 22-1 generated by the straight portion 16-1 passes preferentially through the inside of the magnetic cores 20, which have high magnetic permeability, and penetrates the length direction (direction of progress) cross-section of the metal strip 40 directly below the straight portion 16-1. The magnetic flux 22-2 generated by the straight portion 16-2 passes preferentially through the inside of the magnetic cores 20, which have high magnetic permeability, and penetrates the length direction (direction of progress) cross-section of the metal strip 40 directly below the straight portion 16-2. When this occurs, unlike in LF induction heating, induction current only flows in one direction in a front strip face of the metal strip 40, and so the induction current flows inside the metal strip 40 even when the permeation depth of the induction current is greater than the strip thickness of the metal strip 40. Moreover, as described above, the magnetic flux generated by the induction coils 12 is gathered (concentrated) by the magnetic cores 20, and flux paths guiding the magnetic flux toward the metal strip 40 are formed by the magnetic cores 20. Accordingly, the up-down direction position of the magnetic cores 20 is set as a position enabling the magnetic flux to be gathered (concentrated) effectively, and this up-down direction position of the magnetic cores 20 corresponds to a “specific position” of the present invention. Namely, at the specific position, the magnetic cores 20 are disposed at a separation by a specific distance to the upper side of the metal strip 40. This specific distance can be modified as appropriate according to the shape of the magnetic cores 20 or the like.
Note that similarly to above, in the induction coils 12 disposed at the lower side of the metal strip 40, magnetic flux generated by the straight portions 16 passes preferentially through the inside of the magnetic cores 20 disposed at the lower side of the metal strip 40, and penetrates the length direction (direction of progress) cross-section of the metal strip 40 directly above the straight portions 16. When this occurs, similarly to as described above, induction current only flows in one direction in a back strip face of the metal strip 40, and so the induction current flows inside the metal strip 40, even when the permeation depth of the induction current is greater than the strip thickness of the metal strip 40. Namely, although induction currents arise independently in each of the front and back faces of the metal strip 40, since the induction currents are in the same direction, in the present exemplary embodiment configuration is made such that a single closed circuit 24 having a substantially racetrack shape (closed loop shape) in plan view is formed in the metal strip 40 as illustrated in
Returning to explanation of the configuration of the induction heating device 10, as illustrated in
Each moving mechanism 30 includes a pair of guide rails (tracks) 32 formed in substantially elongated shapes. The pair of guide rails 32 are disposed side-by-side in the length direction of the metal strip 40, corresponding to the two rows of the magnetic cores 20 (only the guide rail of one row is shown in
The second rail portion 32B is bent toward the upper side at the other length direction end portion of the first rail portion 32A, and extends out from the first rail portion 32A in a direction away from the induction coils 12. Each guide rail 32 is provided with plural moving members 34, such as a chain. The moving members 34 are movably coupled to the guide rail 32, and are disposed successively along the length direction of the guide rail 32. A drive section 36 is coupled to the moving members 34, and the moving members 34 are configured so as to be moved along the guide rail 32 by the drive section 36. Moreover, the controller 38 that controls the drive section 36 is electrically connected to the drive section 36. When the drive section 36 is actuated under the control of the controller 38, the plural moving members 34 are moved successively along the length direction of the guide rail 32 by the drive section 36.
Moreover, the magnetic cores 20 described above are fixed to the respective moving members 34. The magnetic cores 20 are disposed successively along the length direction of the guide rail 32, at the specific spacing d. Accordingly, when the moving members 34 are moved along the length direction of the guide rail 32 by the drive section 36, the moving members 34 move relative to the guide rail 32, with the specific spacing d between the magnetic cores 20 maintained. In other words, the plural magnetic cores 20 are configured to move as a single unit along the length direction of the guide rail 32. Accordingly, configuration is made such that the disposed number of the magnetic cores 20 disposed along the first rail portion 32A (namely, the magnetic cores 20 disposed at the specific position) can be increased and decreased. In the induction heating device 10, the disposed number of the magnetic cores 20 disposed at the specific position corresponds to the strip width dimension of the metal strip 40 being conveyed through the induction heating device 10.
Note that in the present exemplary embodiment, equivalent numbers of the magnetic cores 20 are disposed at the spacing d at back face sides of the straight portions 16 of both the upper and lower induction coils 12. However, the disposed number of the magnetic cores 20 is not limited to a specific range at the upper side and the lower side of the metal strip 40. Accordingly, cases arise in which the disposed numbers of the magnetic cores 20 differ between the upper side and the lower side of the metal strip 40, and the disposed number of the magnetic body cores 20 need not necessarily be the same at the upper and lower sides when making initial settings or during running. Moreover, the spacing d between adjacent magnetic cores 20 in the length direction of the guide rail 32 need not necessarily be a uniform interval. The disposed number of the magnetic cores 20 (or the interval between the magnetic cores 20) is set so as to enable a desired heating efficiency to be secured, based on the length of the induction coils 12 along which the magnetic cores 20 are disposed, the dimensions and shape of the magnetic cores 20, and the temperature distribution of the metal strip 40 in the strip width direction.
Next, explanation follows regarding operation and advantageous effects of the first exemplary embodiment.
In
A current (primary current) is passed through the induction coils 12, such that the closed circuit 24 is formed in the metal strip 40, and the metal strip 40 is heated by the induction current 26 flowing around the closed circuit 24, as described above. Accordingly, by conveying the metal strip 40 having a broad strip width along its length direction through the induction heating device 10, the metal strip 40 is continuously heated.
When changing from a metal strip 40 having a broad strip width to a metal strip 40 having a narrow strip width, as illustrated in
When this is performed, the moving members 34 are moved along the guide rails 32 by the drive section 36 of the moving mechanism 30 according to the width dimension of the metal strip 40, and the magnetic cores 20 are moved toward the strip width direction center side of the metal strip 40 together with the moving members 34. A number of the magnetic cores 20 corresponding to the metal strip 40 having a narrow strip width are thereby disposed along each first rail portion 32A (namely, at the specific position). This thereby enables the disposed number of the magnetic cores 20 disposed facing the induction coils 12 and the metal strip 40 in the up-down direction to be reduced. Accordingly, the metal strip 40 having a narrow strip width can be heated with a reduced disposed number of the magnetic cores 20 at the metal strip 40. Note that in
Moreover, when the metal strip 40 having a narrow strip width is replaced with a metal strip 40 having a broad strip width, the state illustrated in
As described above, according to the induction heating device 10 of the first exemplary embodiment, the moving mechanisms 30 are coupled to the magnetic cores 20, and the disposed number of the magnetic cores 20 disposed side-by-side in the strip width direction of the metal strip 40 at the specific position is increased or decreased according to the strip width dimension of the metal strip 40. Namely, a number of the magnetic cores 20 corresponding to the strip width dimension of the metal strip 40 can be disposed at the specific position using the moving mechanisms 30. This thereby enables a more uniform heating temperature to be achieved over the strip width direction of the metal strip 40. Explanation follows regarding this point, drawing comparisons to related technology.
Namely, supposing the induction heating device 10 were to be configured similarly to the induction heating device described in JP-A No. 2002-8838, the disposed number of the magnetic cores 20 disposed along each first rail portion 32A would be fixed, with metal strips 40 with different strip widths being accommodated solely by changing (adjusting) the spacing of the plural magnetic cores 20. In such cases, a number of the magnetic cores 20 corresponding to a metal strip 40 having a narrow strip width are disposed along each first rail portion 32A, and when heating a metal strip 40 having a broad strip width, the magnetic cores 20 are moved so as to widen (enlarge) the spacing of the magnetic cores 20. Namely, the plural magnetic cores 20 are disposed intermittently along the strip width direction of the metal strip 40 across comparatively large gaps. Since no magnetic cores 20 are disposed in these gaps, the metal strip 40 is penetrated by a lower magnetic flux density at portions of the metal strip 40 corresponding to these gaps, thereby reducing the heating temperature. As a result, portions with a high heating temperature and portions with a low heating temperature alternate side-by-side along the strip width direction of the metal strip 40, giving a non-uniform (greater variation in the) heating temperature in the strip width direction of the metal strip 40.
By contrast, in the induction heating device 10 of the present exemplary embodiment, the moving mechanisms 30 move the magnetic cores 20 along the guide rails 32 according to the strip width dimension of the metal strip 40, thereby increasing or decreasing the disposed number of the magnetic cores 20 at the specific position disposed side-by-side in the strip width direction of the metal strip 40. Accordingly, even if the strip width of the metal strip 40 were to change, a number of the magnetic cores 20 corresponding to the strip width of the metal strip 40 can be disposed at the specific position. Namely, when heating a metal strip 40 having a broad strip width, the disposed number of the magnetic cores 20 disposed at the specific position can be increased in comparison to when heating a metal strip 40 having a narrow strip width. This thereby enables gaps between the magnetic cores 20 in the strip width direction of the metal strip 40 to be suppressed from becoming large, even when heating a metal strip 40 having a broad strip width. In other words, the magnetic cores 20 can be disposed at an appropriate spacing even when there is a large change in the strip width dimension of the metal strip 40. This thereby enables a more uniform heating temperature to be achieved over the strip width direction of the metal strip 40 (enables variation in the heating temperature to be suppressed).
Note that the induction heating device 10 includes the strip width/edge position detector 51 and the temperature distribution detector 52. Accordingly, for example, when heating the metal strip 40, the drive section 36 may be controlled by the controller 38 to perform fine adjustments to the position of the magnetic cores 20 in the strip width direction of the metal strip 40 so as to accommodate meanders in the metal strip 40, based on signals output from the strip width/edge position detector 51. Moreover, for example, when heating the metal strip 40, the drive section 36 may be controlled by the controller 38 to perform fine adjustments to the position of the magnetic cores 20 in the strip width direction of the metal strip 40, based on signals output from the temperature distribution detector 52 according to the temperature distribution of the metal strip 40. This thereby enables greater heating temperature uniformity to be effectively achieved over the strip width direction of the metal strip 40.
Explanation follows regarding an induction heating device 200 of a second exemplary embodiment, with reference to
The induction coils 12 of the second exemplary embodiment are configured similarly to the induction coils 12 of the first exemplary embodiment. However, the positions of the curved portion 14 and the flexible conductor 16A differ from in the first exemplary embodiment. Namely, in the second exemplary embodiment, the curved portions 14 are disposed at the width direction outside of the metal strip 40 in plan view (see
Moreover, the flexible conductors 16A of the induction coil 12 disposed at the upper side (lower side) of the metal strip 40 are bent toward the upper side (lower side) at a position toward the other width direction side (one width direction side) of a width direction center line of the metal strip 40. Namely, in plan view, the straight portions 16 of the induction coils 12 disposed at the upper side and the lower side of the metal strip 40 are disposed partially lining up with (overlapping) each other.
The moving mechanisms 30 are disposed corresponding to the induction coils 12. Namely, the first rail portion 32A of the guide rail 32 of the moving mechanism 30 extends along the strip width direction of the metal strip 40, parallel to the straight portion 16 at a position at the upper side of the straight portion 16 of the induction coil 12. Moreover, the second rail portion 32B of the guide rail 32 extends along the up-down direction parallel to the flexible conductor 16A at a position on the metal strip 40 strip width direction one side with respect to the flexible conductor 16A.
In the second exemplary embodiment, as illustrated in
As illustrated in
When this is performed, the moving members 34 are moved along the guide rails 32 by the drive sections 36 of the moving mechanisms 30, and the magnetic cores 20 are moved in the strip width direction of the metal strip 40 together with the moving members 34, according to the strip width dimension of the metal strip 40. Plural of the magnetic cores 20 are thereby disposed along the first rail portions 32A according to the metal strip 40 having a broad strip width. The disposed number of the magnetic cores 20 disposed facing the induction coils 12 and the metal strip 40 in the up-down direction can accordingly be increased.
By contrast, as illustrated in
When this is performed, the moving members 34 are moved along the first guide rails 32A by the drive sections 36 of the moving mechanisms 30, and the magnetic cores 20 are moved toward the strip width direction center side of the metal strip 40 together with the moving members 34, according to the strip width dimension of the metal strip 40. Accordingly, the magnetic cores 20 are disposed along the guide rail 32 corresponding to the metal strip 40 having a narrow strip width, thereby decreasing the disposed number of the magnetic cores 20 disposed facing the induction coil 12 and the metal strip 40 in the up-down direction.
Due to the above, the second exemplary embodiment also enables a number of the magnetic cores 20 corresponding to the strip width of the metal strip 40 to be disposed at the specific position. Accordingly, the second exemplary embodiment also enables a more uniform heating temperature to be achieved over the strip width direction of the metal strip 40.
Moreover, in the second exemplary embodiment, the induction heating device 200 also includes the strip width/edge position detector 51 and the temperature distribution detector 52. Accordingly, for example, similarly to in the first exemplary embodiment, fine adjustments to the position of the magnetic cores 20 in the strip width direction of the metal strip 40 may be performed to accommodate meanders in the metal strip 40. Moreover, for example, fine adjustments to the position of the magnetic cores 20 in the strip width direction of the metal strip 40 may be performed according to the temperature distribution of the metal strip 40.
Explanation follows regarding an induction heating device 300 of a third exemplary embodiment, with reference to
In the first exemplary embodiment, configuration is made in which plural of the magnetic cores 20 are moved as a unit by the moving mechanism 30. However, in the third exemplary embodiment, each of the magnetic cores 20 is configured so as to be capable of being moved independently by the moving mechanism 30. Detailed explanation follows regarding this.
In the third exemplary embodiment, the moving members 34 and the drive section 36 are omitted from the moving mechanism 30, and the moving mechanism 30 includes plural moving devices 302 and approach/separation devices 304. The respective moving devices 302 are movably coupled to the guide rails 32, and each include a drive section, not illustrated in the drawings. The respective moving devices 302 are electrically connected to the controller 38 (see
The approach/separation devices 304 are fixed to the respective moving devices 302. Accordingly, the approach/separation devices 304 are configured so as to move as a unit with the moving devices 302 when the moving devices 302 are moved with respect to the guide rail 32. Each approach/separation device 304 includes a cylinder 304A, operated hydraulically, for example, and the cylinder 304A projects out from the approach/separation device 304 toward the lower side. The approach/separation devices 304 are also electrically connected to the controller 38 (see
A magnetic core 20 is fixed to a lower end of each cylinder 304A. Similarly to in the second exemplary embodiment, the magnetic cores 20 extend along the length direction of the metal strip 40 so as to straddle the pair of straight portions 16 of the induction coil 12. Namely, in the third exemplary embodiment, plural of the magnetic cores 20 lying side-by-side in the strip width direction of the metal strip 40 configure a single row. A lower face of each magnetic core 20 is formed with recesses 20A opening toward the lower side at positions corresponding to the pair of straight portions 16 of the induction coil 12, and the recesses 20A penetrate the magnetic core 20 along the strip width direction of the metal strip 40.
The cylinder 304A of each approach/separation device 304 is configured so as to move the magnetic core 20 in the up-down direction (directions toward and away from the metal strip 40 in the strip thickness direction of the metal strip 40) by extending and retracting in the up-down direction. Specifically, using the cylinder 304A, the magnetic core 20 is configured to move between the specific position (the position of the magnetic cores 20 illustrated by double-dotted dashed lines in
In the induction heating device 300 of the third exemplary embodiment, the controller 38 of the moving mechanism 30 moves the respective moving devices 302 along the guide rails 32 independently of each other according to the strip width dimension of the metal strip 40. A number of the magnetic cores 20 corresponding to the strip width dimension of the metal strip 40 are thereby disposed along the first rail portions 32A. In this state, the magnetic cores 20 are disposed at the standby position, and so the approach/separation devices 304 are actuated by the controller 38 of the moving mechanism 30 in order to dispose the magnetic cores 20 at the specific position. Namely, the cylinders 304A are extended (moved toward) the side of the metal strip 40, disposing the magnetic cores 20 at the specific position. A number of the magnetic cores 20 corresponding to the strip width dimension of the metal strip 40 are thereby disposed at the specific position. Due to the above, the third exemplary embodiment also enables the disposed number of the magnetic cores 20 disposed side-by-side in the strip width direction of the metal strip 40 at the specific position to be increased and decreased according to the strip width dimension of the metal strip 40. This thereby enables a more uniform heating temperature to be achieved over the strip width direction of the metal strip 40.
Moreover, in the third exemplary embodiment, the plural moving devices 302 are configured so as to be capable of moving independently of each other along the guide rails 32, thereby enabling the spacing of adjacent magnetic cores 20 to be changed (adjusted) by the moving devices 302. This thereby enables the placement density of the magnetic cores 20 to be changed according to the heating temperature distribution over the strip width direction of the metal strip 40. For example, it has been found that there is a tendency for a momentary decrease in the heating temperature of the metal strip 40 at portions just inside of both strip width direction edges of the metal strip 40. Accordingly, the spacing of magnetic cores 20 corresponding to the portions just inside of both strip width direction edges of the metal strip 40 may be set narrower than the spacing of magnetic cores 20 corresponding to a strip width direction central portion of the metal strip 40. This thereby enables the density of the magnetic flux penetrating the metal strip 40 to be adjusted in the strip width direction of the metal strip 40. As a result, a more uniform heating temperature can be effectively achieved over the strip width direction of the metal strip 40. Moreover, the moving devices 302 may be moved by the controller 38 based on signals output from the temperature distribution detector 52 so as to make fine adjustments to the positions of the magnetic cores 20 according to the heating temperature distribution over the strip width direction of the metal strip 40.
Moreover, in the third exemplary embodiment, the respective magnetic cores 20 are configured so as to be capable of being moved in the up-down direction by the approach/separation devices 304 (namely, are configured so as to be capable of moving toward and away from the metal strip 40 in the strip thickness direction of the metal strip 40). This thereby enables the density of the magnetic flux penetrating the metal strip 40 to be adjusted by adjusting the up-down direction positions of the magnetic cores 20 disposed at the specific position. Accordingly, for example, the controller 38 can finely control the heating temperature of the metal strip 40 according to the heating temperature distribution over the strip width direction of the metal strip 40 by actuating the approach/separation devices 304 based on signals output from the temperature distribution detector 52. Accordingly, such cases also enable a more uniform heating temperature to be effectively achieved over the strip width direction of the metal strip 40.
In the third exemplary embodiment, configuration is made in which, after using the moving devices 302 to move the magnetic cores 20 in the strip width direction of the metal strip 40 with the cylinders 304A of the approach/separation devices 304 in a retracted state, the cylinders 304A of the approach/separation devices 304 are extended toward the side of the metal strip 40 such that from the standby position, the magnetic cores 20 are disposed at the specific position. Namely, when the magnetic cores 20 are moved in the strip width direction of the metal strip 40, the magnetic cores 20 are disposed separated to the upper side of the induction coils 12. This thereby enables collisions between inner peripheral faces of the recesses 20A of the magnetic cores 20 and the straight portions 16 of the induction coils 12 to be avoided when moving the magnetic cores 20 in the strip width direction of the metal strip 40, even supposing the magnetic cores 20 were to vibrate so as to undergo displacement along the length direction of the metal strip 40.
Moreover, in the third exemplary embodiment, the induction heating device 300 still includes the strip width/edge position detector 51. Accordingly, similarly to in the first exemplary embodiment, for example, fine adjustments to the position of the magnetic cores 20 in the strip width direction of the metal strip 40 may be performed so as to accommodate meanders in the metal strip 40.
In the third exemplary embodiment, configuration is made in which the magnetic cores 20 are moved from the standby position to the specific position by the approach/separation devices 304 after the magnetic cores 20 have been moved up to the standby position by the moving devices 302. Alternatively, the moving devices 302 may be moved along the guide rail 32 to dispose the magnetic cores 20 at the specific position with the cylinders 304A of the approach/separation devices 304 in a pre-extended state. Such cases enable the position of the magnetic cores 20 in the up-down direction to be adjusted similarly to as described above by actuating the approach/separation devices 304 after the magnetic cores 20 have been disposed at the specific position.
In the third exemplary embodiment, the moving mechanism 30 is configured including the plural moving devices 302 and approach/separation devices 304. Alternatively, the approach/separation devices 304 may be omitted from the moving mechanism 30, and the magnetic cores 20 may be fixed with respect to the moving devices 302. In such cases, configuration is made such that the magnetic cores 20 disposed at the specific position by moving the magnetic cores 20 in the strip width direction of the metal strip 40 with the moving devices 302.
Explanation follows regarding an induction heating device 400 of a fourth exemplary embodiment, with reference to
In the third exemplary embodiment, configuration is made such that the respective magnetic cores 20 are capable of being moved in the strip width direction of the metal strip 40 by the moving devices 302. However, in the fourth exemplary embodiment, configuration is made such that the magnetic cores 20 are not movable in the strip width direction of the metal strip 40, while making configuration such that the respective magnetic cores 20 are capable of moving in the strip thickness direction of the metal strip 40. Detailed explanation follows regarding this.
In the fourth exemplary embodiment, a support member 402 extending along the strip width direction of the metal strip 40 is provided instead of the guide rail 32. Moreover, in the fourth exemplary embodiment, the moving devices 302 are omitted from the moving mechanism 30 of the third exemplary embodiment, and the approach/separation devices 304 are fixed to the support member 402. Although not illustrated in the drawings, the induction coils 12 extend along the strip width direction of the metal strip 40. Namely, regarding the flexible conductors 16A of the induction coils 12, the curved portions 14 are omitted, and the flexible conductors 16A extend along the strip width direction of the metal strip 40.
The approach/separation devices 304 and the magnetic cores 20 are disposed side-by-side at a specific spacing in the strip width direction of the metal strip 40 in advance. Moreover, the disposed numbers thereof are set so as to accommodate a metal strip 40 having a broad strip width. Moreover, the magnetic cores 20 are configured to move between the standby position (see the magnetic cores 20 illustrated by solid lines in
In the induction heating device 400 of the fourth exemplary embodiment, the controller 38 of the moving mechanism 30 actuates the approach/separation devices 304 facing the metal strip 40 in the strip thickness direction, and extends the cylinders 304A such that the magnetic cores 20 are moved from the standby position to the specific position. A number of the magnetic cores 20 corresponding to the strip width dimension of the metal strip 40 are thereby disposed in the specific position. This thereby enables the disposed number of the magnetic cores 20 at the specific position disposed side-by-side in the strip width direction of the metal strip 40 to be increased or decreased according to the strip width dimension of the metal strip 40. Accordingly, the fourth exemplary embodiment also enables a more uniform heating temperature to be achieved over the strip width direction of the metal strip 40.
Moreover, in the fourth exemplary embodiment, although the magnetic cores 20 are incapable of moving in the length direction of the guide rail 32, the controller 38 is configured to control the respective approach/separation devices 304 independently of each other. This thereby enables the spacing of the magnetic cores 20 disposed at the specific position to be changed (adjusted) as appropriate by leaving some of the approach/separation devices 304 out of the approach/separation devices 304 facing the metal strip 40 in the strip thickness direction in a non-actuated state. Accordingly, similarly to in the third exemplary embodiment, the placement density of the magnetic cores 20 can be changed according to the heating temperature distribution over the strip width direction of the metal strip 40. This thereby enables a more uniform heating temperature to be effectively achieved over the strip width direction of the metal strip 40.
Moreover, in the fourth exemplary embodiment, similarly to in the third exemplary embodiment, the respective magnetic cores 20 are configured so as to be capable of being moved in the up-down direction by the approach/separation devices 304. This thereby enables the density of the magnetic flux penetrating the metal strip 40 to be adjusted by adjusting the up-down direction positions of the magnetic cores 20 disposed at the specific position. Similarly to the third exemplary embodiment, the fourth exemplary embodiment accordingly enables a more uniform heating temperature to be effectively achieved over the strip width direction of the metal strip 40.
Note that in the magnetic cores 20 of the first and second exemplary embodiments, the recesses 20A of the third and fourth exemplary embodiments are not formed in the magnetic cores 20. However, as illustrated in
In the first to the fourth exemplary embodiments, the induction coils 12 are disposed on both strip thickness direction sides (at the upper side and the lower side) of the metal strip 40. However, configuration may be made in which the induction coils 12 are disposed at either the upper side or the lower side of the metal strip 40. For example, the induction coils 12 are formed in a substantially racetrack shape in plan view, and the length of the induction coils 12 is preset to a length corresponding to a metal strip 40 having a broad strip width. The induction coils 12 are configured so as to be incapable of moving, and the induction coils 12 are disposed in advance at positions corresponding to the metal strip 40 having a broad strip width. This thereby enables the induction coils 12 to accommodate metal strips 40 of different strip widths (narrow strip widths). Moreover, in such cases, the guide rails 32 of the moving mechanisms 30 extend in the strip width direction of the metal strip 40, similarly to the support member 402 of the fourth exemplary embodiment. Actuating the moving mechanisms 30 according to the strip width dimension of the metal strip 40 enables a number of the induction coils 12 corresponding to the strip width dimension of the metal strip 40 to be disposed at the specific position.
In the first, third, and fourth exemplary embodiments, the curved portions 14 of the induction coils are disposed facing both width direction edge portions of the metal strip 40 in the strip thickness direction of the metal strip 40. Alternatively, as illustrated in
In the first to the fourth exemplary embodiments, the induction coils 12 (curved portions 14) are configured so as to be capable of moving in the strip width direction of the metal strip 40. However, the induction coils 12 may be configured so as to be incapable of moving. For example, the length of the induction coils 12 in the strip width direction of the metal strip 40 may be preset according to a metal strip 40 having a broad strip width, thereby enabling metal strips 40 with different strip widths (narrow strip widths) to be accommodated. In such cases, the magnetic cores 20 disposed at the specific position can be increased and decreased by actuating the moving mechanism 30 according to metal strips 40 of differing strip widths. This thereby enables the configuration of the induction heating device 10, 200, 300, 400 to be made simpler than in cases in which the induction heating device 10, 200, 300, 400 are configured with the induction coils 12 that are capable of moving.
Explanation follows regarding an induction heating device 500 of a fifth exemplary embodiment, with reference to
In the third exemplary embodiment, the pair of straight portions 16 of each looped induction coil 12 are both provided on the same strip face side of the metal strip 40. However, in the fifth exemplary embodiment, one out of the pair of the straight portions 16 of a looped induction coil 12 (the straight portion 16 labeled 16C) is provided on the front face side of the metal strip 40 (on the arrow A direction side in
In the case of the LF method described above, induction currents of the same size as each other flow in opposite directions to each other at the front and reverse faces of the metal strip 40. Accordingly, in cases in which the metal strip 40 is non-magnetic, or is a steel sheet that and loses its magnetism on exceeding its Curie temperature, the current permeation depths δ become deep and interfere with each other, and the induction currents stop flowing. However, in the fifth exemplary embodiment, the pair of straight portions 16 are provided offset to each other in the conveyance direction of the metal strip 40 (the arrow E direction in
Plural of the magnetic cores 20 are disposed on the respective opposite sides from the metal strip 40 with respect to the pair of straight portions 16 of the induction coil 12. Namely, the plural magnetic cores 20 are disposed at the respective back face sides of the pair of straight portions 16 as viewed from the length direction of the metal strip 40. The plural magnetic cores 20 provided on the front face side (arrow A direction side) of the metal strip 40 are respectively coupled to the moving mechanism 30 provided on the front face side (arrow A direction side). Configuration is made such that the plural magnetic cores 20 provided on the front face side of the metal strip 40 are moved independently of each other by the moving mechanism 30 by controlling the moving mechanism 30 with the controller 38, and are capable of moving in the up-down direction (the arrow A and B directions) and in the strip width direction of the metal strip 40 (the arrow C and D directions). The plural magnetic cores 20 provided on the reverse face side (arrow B side) of the metal strip 40 are respectively coupled to the moving mechanism 30 provided on the reverse face side (arrow B direction side). Configuration is made such that the plural magnetic cores 20 provided on the reverse face side of the metal strip 40 are moved independently of each other by the moving mechanism 30 by controlling the moving mechanism 30 with the controller 38, and are capable of moving in the up-down direction (the arrow A and B directions) and in the strip width direction of the metal strip 40 (the arrow C and D directions).
The magnetic cores 20 are moved in the up-down direction (the arrow A and B directions) between the specific position and the standby position by the moving mechanism 30. Note that the magnetic cores 20 may be disposed at either position of the specific position or the standby position, and may also be disposed at a position partway between the specific position and the standby position (an intermediate position). When the magnetic cores 20 are disposed at the specific position, similarly to in the third exemplary embodiment, the magnetic cores 20 are disposed at the back face of the straight portions 16 so as to straddle the straight portions 16 of the induction coil 12.
The disposed number of the plural magnetic cores 20 is set as a number capable of accommodating a metal strip 40 having the maximum strip width that can be heated by the induction heating device 500. Out of the plural magnetic cores 20, an appropriate number of the magnetic cores 20 at appropriate positions are pulled back (moved away) from the straight portion 16 of the induction coil 12 or moved in the strip width direction (the arrow C and D directions) by the moving mechanism 30 according to the strip width and meandering state of the metal strip 40. Note that the strip width and meandering state of the metal strip 40 may, for example, be detected by detecting both edge portions of the metal strip 40 in the strip width direction using the strip width/edge position detector 51 (see
Note that when adjusting the temperature distribution in the strip width direction of the metal strip 40 (the arrow C and D directions) using the plural magnetic cores 20, the moving mechanism 30 may be controlled by the controller 38 according to signals from the temperature distribution detector 52 (see
In
Note that in the first exemplary embodiment to the fourth exemplary embodiment described above, each induction coil 12 is configured including the curved portion 14 and a pair of the straight portions 16. However, the induction coils 12 in the first to the fourth exemplary embodiments may be configured similarly to the fifth exemplary embodiment. Namely, as illustrated in
The disclosure of Japanese Patent Application No. 2014-179664, filed on Sep. 3, 2014, and the disclosure of Japanese Patent Application No. 2014-181692, filed on Sep. 5, 2014 are incorporated in their entirety by reference herein.
Supplementary Explanation
(1) An induction heating device for a metal strip, the induction heating device including: an induction coil that is provided on one strip thickness direction side or on both strip thickness direction sides of a metal strip that travels along a length direction thereof, and that induces an induction current in the metal strip when a primary current is passed through the induction coil, the induction current configuring a closed loop as viewed from the strip thickness direction of the metal strip; plural magnetic cores that face the metal strip in the strip thickness direction and that are disposed at a specific position separated from the metal strip by a specific distance so as to concentrate magnetic flux generated by the induction coil; and a moving mechanism that is coupled to the magnetic cores, and that moves the magnetic cores so as to increase or decrease a disposed number of the magnetic cores at the specific position disposed side-by-side along a strip width direction of the metal strip.
(2) The metal strip induction heating device of (1), wherein the moving mechanism is configured including: a guide rail that is provided on a side that is opposite from the metal strip with respect to the induction coil, and that extends along the strip width direction of the metal strip; and a moving member that is provided at the guide rail so as to be capable of moving, that is coupled to the magnetic cores, and that is moved along a length direction of the guide rail so as to dispose the plural magnetic cores at the specific position in a state in which a spacing of the plural magnetic cores in the length direction of the guide rail is maintained.
(3) The metal strip induction heating device of (1), wherein the moving mechanism is configured including a guide rail that is provided on a side that is opposite from the metal strip with respect to the induction coil, and that extends along the strip width direction of the metal strip, and plural moving devices that are provided at the guide rail so as to be capable of moving, that are coupled to the plural respective magnetic cores, and that are moved along a length direction of the guide rail so as to dispose the magnetic cores at the specific position, and the plural moving devices are configured so as to be capable of moving independently of each other along the length direction of the guide rail.
(4) The metal strip induction heating device of (3), wherein the moving mechanism includes plural approach/separation devices that are respectively fixed to the plural moving devices, and that couple the moving devices and the magnetic cores together, and the plural approach/separation devices are configured so as to be capable of independently moving the respective magnetic cores toward the metal strip in the strip thickness direction of the metal strip.
(5) The metal strip induction heating device of (1), wherein the moving mechanism includes plural approach/separation devices that are respectively coupled to the magnetic cores, and the plural approach/separation devices are provided on a side that is opposite from the metal strip with respect to the magnetic cores, and are configured so as to be capable of independently moving the respective magnetic cores toward and away from the metal strip in the strip thickness direction of the metal strip, and the plural approach/separation devices are actuated so as to dispose the magnetic cores either at a standby position not contributing to concentrating magnetic flux generated by the induction coil, or at the specific position.
(6) The metal strip induction heating device of (5), wherein the approach/separation devices are configured so as to be capable of moving the magnetic cores to an intermediate position between the specific position and the standby position.
(7) The induction heating device of (5) or (6), wherein the moving mechanism includes plural moving devices respectively coupled to the plural approach/separation devices, and the plural moving devices are configured so as to be capable of independently moving the respective approach/separation devices in the strip width direction of the metal strip.
(8) The induction heating device of any one of (1) to (7), wherein a controller is connected to the moving mechanism, and the controller actuates the moving mechanism based on information of at least one out of a temperature distribution of the metal strip, or a profile of the metal strip in the strip width direction.
(9) The induction heating device of (8), wherein a temperature distribution detector that detects a temperature distribution of the metal strip and a strip width/edge position detector that detects the profile of the metal strip in the strip width direction are connected to the controller, and the controller actuates the moving mechanism based on at least one signal output to the controller from the temperature distribution detector or from the strip width/edge position detector.
An induction heating device for a metal strip of the present disclosure is an induction heating device wherein, at a same-face side or at both face side strip faces of a metal strip that travels along a length direction thereof, at the same strip face side, two or more conductor faces of an induction coil facing the strip face are formed separated by a distance. When a primary current is passed through the induction coil, magnetic flux penetrates the metal strip in the direction of travel without penetrating the metal strip in its thickness direction, inducing an induction current in a closed circuit in the strip face of the metal strip. Plural magnetic cores that move along the induction coil are disposed independently of the induction coil in the vicinity of a back face of the induction coil.
An induction heating device for a metal strip of the present disclosure, is an induction heating device wherein, conductor faces of an induction coil facing a strip face at one strip face out of front and reverse strip faces of a metal strip that travels along a length direction thereof are formed separated by a distance in a same plane, and conductor faces of the induction coil facing the other face out of the front and reverse strip faces of the metal strip are formed separated by a distance in a same plane. When a primary current is passed through the induction coil, magnetic flux is generated penetrating the metal strip in the strip thickness direction. Plural magnetic cores that move along the induction coil are disposed independently of the induction coil in the vicinity of back faces of the induction coil.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-179664 | Sep 2014 | JP | national |
| 2014-181692 | Sep 2014 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/075133 | 9/3/2015 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2016/035867 | 3/10/2016 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4585916 | Rich | Apr 1986 | A |
| 6180933 | Demidovitch | Jan 2001 | B1 |
| 6608290 | Robinson | Aug 2003 | B1 |
| 20020011486 | Anderhuber | Jan 2002 | A1 |
| 20070235446 | Cao et al. | Oct 2007 | A1 |
| 20080264932 | Hirota | Oct 2008 | A1 |
| 20100072192 | Hirota | Mar 2010 | A1 |
| 20100108665 | Hirota | May 2010 | A1 |
| Number | Date | Country |
|---|---|---|
| 2157193 | Feb 2010 | EP |
| 8-153577 | Feb 1988 | JP |
| 63-27836 | Feb 1988 | JP |
| 11-500262 | Jan 1999 | JP |
| 2001-32016 | Feb 2001 | JP |
| 2001-160481 | Jun 2001 | JP |
| 2002-8838 | Jan 2002 | JP |
| 2002-151245 | May 2002 | JP |
| 2004-296368 | Oct 2004 | JP |
| 2006-294396 | Oct 2006 | JP |
| 2007-95651 | Oct 2006 | JP |
| 2008-204648 | Sep 2008 | JP |
| 2008 288200 | Nov 2008 | JP |
| 2009-259588 | Nov 2009 | JP |
| 2012-195316 | Oct 2012 | JP |
| WO 9626296 | Aug 1996 | WO |
| Entry |
|---|
| Extended European Search Report dated Mar. 8, 2018, for corresponding European Application No. 15838082.4. |
| International Preliminary Report on patentability for PCT/JP2015/075133 (PCT/IPEA/409) dated Sep. 26, 2016. |
| International Search Report for PCT/JP2015/075133 dated Nov. 24, 2015. |
| Written Opinion of the International Searching Authority for PCT/JP2015/075133 (PCT/ISA/237) dated Nov. 24, 2015. |
| Number | Date | Country | |
|---|---|---|---|
| 20170260604 A1 | Sep 2017 | US |
