Metal plate induction heating device, metal plate processing equipment, and metal plate induction heating method

Abstract

This induction heating device for a metal plate is provided with: a first conductor member which faces at least one of the front surface and the rear surface of the metal plate, and which is disposed across the metal plate in the width direction; a second conductor member which is separated from the first conductor member by a first distance in the through-plate direction of the metal plate, faces at least one of the front surface and the back surface of the metal plate, and is disposed across the metal plate in the width direction; a connection member that forms a primary closed circuit by connecting the first conductor member and the second conductor member to each other at a position separated from an end portion of the metal plate in the width direction; and an AC power source connected to the primary closed circuit, the first distance being greater than the sum of the dimensions of the first conductor member and the second conductor member in the direction in which the metal plate passes.

Description

Technical Field

[0001] The present invention relates to an induction heating device for a metal plate, a processing device for a metal plate, and an induction heating method for a metal plate. Background Art

[0002] In the cold rolling of harder steel materials such as stainless steel and high-strength steel, the brittleness of the steel materials is higher than usual, so end cracks sometimes occur at the ends in the width direction. For example, Japanese Patent Publication No. 2010-221224 describes a technology for dealing with such end cracks. More specifically, Japanese Patent Publication No. 2010-221224 describes the following technology: using a C-shaped induction coil configured to clamp the ends of the steel plate in the width direction from top and bottom, the ends are inductively heated to reduce the deformation resistance of the steel plate at the ends, thereby preventing end cracks.

[0003] In addition, in the case of thick steel such as hot-rolled slabs, the ends of the steel are cooled before being drawn out of the heating furnace and rough rolling and finishing rolling. Therefore, in order to improve the rolling dimensional accuracy of the hot-rolled piece and stabilize the quality, a transverse induction heating device such as the above-mentioned C-shaped induction coil is usually installed in front of the finishing mill.

[0004] Furthermore, in order to prevent poor alloying due to a drop in end temperature during alloying of hot-dip galvanizing, for example, Japanese Patent Application Laid-Open No. 2009-149970 describes a flame-based temperature compensation device having an end detection mechanism and a movement mechanism. Summary of the invention

[0005] Problems to be solved by the invention

[0006] In the above-mentioned Japanese Patent Publication No. 2010-221224, the following technology is also recorded: by providing a trolley that moves the induction coil in the width direction of the steel plate and a position controller that controls the movement of the trolley, the appropriate overlapping length of the induction coil and the steel plate is maintained in correspondence with the change in the width of the steel plate and the meandering during transportation. However, as a previous problem, in the case of a C-shaped induction coil, due to the magnetic flux leaking to the outside of the induction coil, a large range outside the part clamped by the induction coil is also inductively heated. On the other hand, in order to prevent the end of the metal plate from breaking, it is sufficient to heat a narrow range near the end of the metal plate in the width direction. Therefore, the technology recorded in Japanese Patent Publication No. 2010-221224 is not necessarily effective at least in terms of suppressing power consumption. In addition, there is a problem that if the induction coil gap is not narrowed, heating cannot be performed effectively. For a heated object with a bad shape such as a hot-rolled steel plate, it is possible to cause damage to the device due to contact with the induction coil. Furthermore, auxiliary equipment such as a detection mechanism and a moving mechanism control device for dealing with meandering conveyance are indispensable, and there is also a disadvantage in terms of cost.

[0007] In addition, when the steel plate end is heated with a flame as in Japanese Patent Application Laid-Open No. 2009-149970, there are problems in terms of capacity such as the low heating capacity of the flame and the low heating efficiency, and the need for auxiliary equipment such as an end detection mechanism and a moving mechanism.

[0008] Therefore, the purpose of the present disclosure is to provide the following technology: even if the width of the metal plate changes or the metal plate is conveyed in a winding manner, the temperature of the end of the metal plate is increased by effectively heating only a specific range of the end in the width direction of the metal plate, thereby stabilizing the quality of the end, preventing the end of the metal plate from cracking, improving the rolling dimensional accuracy, avoiding poor alloying, etc., and solving the problems caused by the temperature drop at the end of the plate.

[0009] Means used to solve problems

[0010] A technical solution disclosed in the present invention is an induction heating device for a metal plate, comprising: a first conductor component, which is opposite to at least one of the surface and the back surface of the metal plate and is arranged across the metal plate in the width direction; a second conductor component, which is separated from the first conductor component by a first distance in the through-plate direction of the metal plate, is opposite to at least one of the surface and the back surface of the metal plate and is arranged across the metal plate in the width direction; a connecting component, which connects the first conductor component and the second conductor component to each other at a position away from the width-direction end of the metal plate to form a primary closed circuit; and an AC power supply connected to the primary closed circuit; the first distance is greater than the total value of the dimensions of the first conductor component and the second conductor component in the through-plate direction of the metal plate.

[0011] Another technical scheme disclosed in the present invention is an induction heating method for a metal plate, comprising: a process of passing an alternating current through a primary closed circuit formed by a first conductor component, a second conductor component, and a connecting component, wherein the first conductor component is opposite to at least one of the surface and back sides of the metal plate and is arranged across the metal plate in the width direction; the second conductor component is opposite to at least one of the surface and back sides of the metal plate, is separated from the first conductor component by a first distance in the passing direction of the metal plate, and is arranged across the metal plate in the width direction; the connecting component connects the first conductor component and the second conductor component to each other at a position away from the width direction end of the metal plate, and a process of inductively heating the width direction end of the metal plate by passing a secondary closed circuit formed by an induced current generated in the metal plate in the regions respectively opposite to the first conductor component and the second conductor component through the width direction end of the metal plate.

[0012] Effects of the Invention

[0013] According to the present disclosure, even if the width of the metal plate changes or it is conveyed in a winding manner, the temperature of the end of the metal plate can be increased by effectively heating only a specific range of the end in the width direction of the metal plate, thereby stabilizing the quality of the end, preventing the end of the metal plate from cracking, improving the rolling dimensional accuracy, avoiding poor alloying, etc., and solving the problems caused by the temperature drop at the end of the plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a top view of the induction heating device for a metal plate according to the first embodiment of the present disclosure.

[0015] Figure 2A is equivalent to Figure 1 A side view of the induction heating device shown along line 2A-2A.

[0016] Figure 2B Yes means Figure 1 A side view of a modified example of the induction heating device shown in FIG. Figure 2A corresponding side view).

[0017] Figure 2C Yes means Figure 1 A side view of another variant of the induction heating device shown in FIG. Figure 2A corresponding side view).

[0018] Figure 3 It is conceptually expressed in Figure 1 and Figure 2A to Figure 2C Figure 1 shows an example of the induced current in a metal plate.

[0019] Figure 4 It is a top view of the induction heating device for a metal plate according to the second embodiment of the present disclosure.

[0020] Figure 5 It is a top view of an induction heating device for a metal plate according to another example of the second embodiment of the present disclosure.

[0021] Fig. 6A It is a cross-sectional view for explaining the third embodiment of the present disclosure.

[0022] Figure 6B It is a cross-sectional view for explaining the third embodiment of the present disclosure.

[0023] Fig. 7A It is a cross-sectional view for explaining another example of the third embodiment of the present disclosure.

[0024] Figure 7B It is a cross-sectional view for explaining another example of the third embodiment of the present disclosure.

[0025] Fig. 8A It is a top view of an induction heating device for a metal plate (narrow in width) according to a fourth embodiment of the present disclosure.

[0026] Figure 8B It is a top view of an induction heating device for a metal plate (with a wide width) according to a fourth embodiment of the present disclosure.

[0027] Fig. 9 is equivalent to Fig. 8A A side view of the induction heating device shown along line 9-9.

[0028] Fig.10 This is a graph showing analysis results for verifying the effect of heating the widthwise end portions of the metal plate in the embodiment of the present disclosure.

[0029] Fig.11This is a graph showing analysis results for verifying the effect of heating the widthwise end portions of the metal plate in the embodiment of the present disclosure.

[0030] Fig.12 It is a side view for demonstrating the movable part used in the embodiment of this disclosure.

[0031] Fig.13 It means use Fig.12 A side view of a state in which the movable part changes the distance between the conductive parts.

[0032] Fig.14A It is a side view for explaining a modified example of the movable part used in the embodiment of the present disclosure.

[0033] Fig. 14B is from Fig.14A FIG. 14B is viewed in the direction of arrow 14B.

[0034] Fig.15 It means use Fig.12 A side view of a state in which the movable part changes the distance between the conductive parts.

[0035] Fig.16 This is a plan view of a state where the induction heating device according to one embodiment of the present disclosure is applied to thick metal.

[0036] Fig.17 It is observation Fig.16 The side view of the thick metal shown is a side view showing the current flowing in the width direction end.

[0037] Fig.18 It is a plan view of another example of an induction heating device for a metal plate according to the second embodiment of the present disclosure.

[0038] Fig.19 It means that Fig.18 A top view of the induction heating device after the circuit is switched.

[0039] Fig. 20 It is a schematic configuration diagram showing an example of processing equipment using the induction heating device for a metal plate according to an embodiment of the present disclosure.

[0040] Fig.21 It is a schematic configuration diagram showing another example of processing equipment using the induction heating device for a metal plate according to the embodiment of the present disclosure.

[0041] Fig. 22 It is a schematic configuration diagram showing another example of processing equipment using the induction heating device for a metal plate according to the embodiment of the present disclosure. DETAILED DESCRIPTION

[0042] Below, while referring to the attached Figure 1 In addition, in this specification and drawings, components having substantially the same functional structure are given the same reference numerals, and repeated descriptions are omitted.

[0043] (First embodiment)

[0044] Figure 1 is a top view of an induction heating device for a metal plate according to a first embodiment of the present disclosure. Figure 2A is equivalent to Figure 1 A side view of the induction heating device shown in FIG. Figure 1 2 , the induction heating device 100 according to the present embodiment is a device that heats a metal strip S as a metal plate by electromagnetic induction. Here, the metal strip S used in the present embodiment is, for example, a belt-shaped thin plate, but the present disclosure is not limited thereto.

[0045] The induction heating device 100 of this embodiment includes conductor components 110, 120, connection components 131, 132, and an AC power supply 140. The conductor component 110 faces at least one of the surface and the back of the metal strip S, and is arranged so as to cross the metal strip S in the width direction. The conductor component 120, like the conductor component 110, also faces at least one of the surface and the back of the metal strip S, and is arranged so as to cross the metal strip S in the width direction. The conductor component 120 extends from the conductor component 110 in the through-plate direction of the metal strip S (in the direction of the metal strip S). Figure 1 The conductor components 110 and 120 are separated by a distance L in the direction indicated by the arrow PD. Here, the distance L is the inner distance between the conductor components 110 and 120. The distance L (inner distance) is greater than the sum of the dimensions B1 and B2 of the conductor components 110 and 120 in the through-plate direction of the metal strip S (L>B1+B2). In addition, the distance L in this embodiment is an example of the first distance in the present disclosure.

[0046] In the top view, the connection members 131 and 132 connect the conductor members 110 and 120 to each other at a position away from the width direction end of the metal strip S to form a primary closed circuit 101, and the AC power supply 140 is connected to the primary closed circuit 101. The connection members 131 and 132 only need to be away from the width direction end SE of the maximum plate width of the metal strip S. Specifically, the distance E from the connection members 131 and 132 to the width direction end SE of the metal strip S is preferably 3% to 12% of the maximum width Wmax of the metal strip S, and more preferably 5% to 10%. The relationship between the distance E and the maximum width Wmax is preferably based on the meandering amount of the conveyor line on which the metal strip S is conveyed. In addition, when the distance E is less than 3% of the maximum width Wmax, the width direction end SE of the metal strip S may contact the connection member 131 or the connection member 132 due to meandering conveyance. On the other hand, when the distance E exceeds 12% of the maximum width Wmax, there is a possibility that the size of the device may be increased and the impedance of the primary closed circuit 101 may be increased.

[0047] The conductor members 110 and 120 face at least one of the front and back surfaces of the metal strip S. Therefore, when an AC current is supplied to the primary closed circuit 101 by the AC power source 140, a magnetic field generated around the conductor members 110 and 120 generates an induced current in the metal strip S as described below.

[0048] Here, if Figure 2A As shown, the conductor components 110 and 120 of this embodiment include two plate portions 111 and 112 and two plate portions 121 and 122 facing each other on the surface and back of the metal strip S. In other words, the conductor component 110 is configured so that the plate portions 111 and 112 face the surface and back of the metal strip S, respectively, and the conductor component 120 is configured so that the plate portions 121 and 122 face the surface and back of the metal strip S, respectively. In addition, the present disclosure is not limited to this, and may also be as follows Figure 2B In the example shown, the plate portion 111 of the conductor component 110 is opposite to the surface of the metal strip S, and the plate portion 122 of the conductor component 120 is opposite to the back surface of the metal strip S. Alternatively, the plate portion 112 of the conductor component 110 is opposite to the back surface of the metal strip S, and the plate portion 121 of the conductor component 120 is opposite to the surface of the metal strip S. Figure 2C In the example shown, the plate portion 111 of the conductor component 110 and the plate portion 121 of the conductor component 120 are only opposed to the surface of the metal strip S, but the plate portion 112 of the conductor component 110 and the plate portion 122 of the conductor component 120 may be only opposed to the back surface of the metal strip S. In other words, the conductor component 110 and the conductor component 120 are arranged to face the same side of the metal strip S, respectively.

[0049] In this embodiment, if Figure 1 and Figure 2A As shown, an air-core coil is formed by the conductor members 110 and 120 and the connecting members 131 and 132. The primary closed circuit 101 formed by the air-core coil is connected to an AC power source 140.

[0050] Figure 3 It is conceptually expressed in Figure 1 and Figure 2A FIG. 1 is a diagram of the induced current I generated in the metal strip S in the example of FIG. The secondary closed circuit 102 is formed by the induced current I generated in the regions of the metal strip S that are respectively opposed to the conductor parts 110 and 120 of the induction heating device 100, and flows in the width direction of the metal strip S in the regions that are respectively opposed to the conductor parts 110 and 120, and passes through the width direction end parts SE of the metal strip S between the two ends of these regions. In this way, the induced current of the secondary closed circuit 102 flows around the metal strip S. The induced current I flowing through the secondary closed circuit 102 can suppress the heat generation in the central part of the metal strip S because the current density is small, but in the width direction end parts SE, the current density in the limited range away from the end parts becomes high due to the skin effect in which the high frequency current is concentrated at the end parts. As a result, the width direction end parts SE of the metal strip S can be effectively heated.

[0051] In order to solve the problem of the so-called LF heating method in which a thin plate is heated by a spiral tube coil, that is, non-magnetic parts cannot be heated due to the penetration depth of the current, according to Figure 3 It can be seen that in the present disclosure, the conductors are staggered so as not to overlap in the traveling direction, so that the circulating currents do not overlap, and therefore both non-magnetic and magnetic parts can be heated.

[0052] In addition, by separating the conductor components 110 and 120 by a distance L in the passing direction of the metal strip S, the heating duration of the width direction end SE of the metal strip S becomes longer. Specifically, when the passing speed of the metal strip S is v, the heating is continued during the period from the width direction end SE of the metal strip S passing under (or above) the conductor component 120 to the period from the width direction end SE of the metal strip S passing under (or above) the conductor component 110, so the heating duration is L / v. On the other hand, in the width direction center of the metal strip S, the heating is only heated during the period of passing under (or above) the conductor component 120 and the period of passing under (or above) the conductor component 110, so the heating duration is (B1+B2) / v. Therefore, by setting L>B1+B2, the heating duration can be made longer at the width direction end SE of the metal strip S than at the width direction center. Thus, the heat generation Qc of the widthwise center portion and the heat generation Qe of the widthwise end portions SE of the metal strip S can be adjusted by the distance L between the conductor members 110 and 120 and their respective dimensions B1 and B2. In addition, the heat generation Qc and Qe can also be adjusted by the frequency f of the AC current.

[0053] More specifically, the heat generation Qc of the central part of the metal strip S in the width direction can be calculated by the following formula (1) using the above-mentioned quantities and the plate width W, plate thickness t, resistivity ρ1 of the part opposite to the conductor component 110, and resistivity ρ2 of the part opposite to the conductor component 120 of the metal strip S.

[0054] [Formula 1]

[0055]

[0056] On the other hand, the heat generation Qe (total of both sides) of the width direction end portion SE of the metal strip S can be calculated by the following formula (2) using the above-mentioned quantities and the resistivity ρe at the width direction end portion SE of the metal strip S.

[0057] [Formula 2]

[0058]

[0059] The ratio of the heat generation amount Qc of the width direction center portion of the metal strip S to the heat generation amount Qe of the width direction end portions SE is expressed by the following formula (3) based on the above-mentioned formulas (1) and (2).

[0060] [Formula 3]

[0061]

[0062] Based on the above formula (3), conditions for intensively heating the width end portions SE while suppressing the temperature rise in the width center portion of the metal strip S are considered. In formula (3), if ρ1=ρ2=ρc is assumed, the following formula (4) is obtained.

[0063] [Formula 4]

[0064]

[0065] Here, using the specific gravity γ of the metal strip S, the specific heats Cpc and Cpe of the widthwise central portion and the widthwise end portions SE, the respective temperature rise amounts ΔTc and ΔTe, and the average size B of the conductor member = (B1 + B2) / 2, the calorific values ​​Qc and Qe are expressed as in the following equations (5) and (6). Substituting equations (5) and (6) into equation (4) and rearranging them, equations (7) and (8) are obtained.

[0066] [Formula 5]

[0067] QC=2×γ×W×B×ι×Cpc×ΔTc (5)

[0068] Qc=2×γ×L×D×t×Cpc×ΔTc (6)

[0069]

[0070]

[0071] In the above formula (8), when B=0.1m, D=0.07m, the temperature rise ΔTc of the central portion in the width direction of the metal strip S is suppressed to 10°C, and ΔTe of the width end SE is set to 500°C, by substituting the specific heats Cpc, Cpe and resistivities ρc, ρe corresponding to the respective temperature rises, the appropriate distance L is calculated as follows. In addition, in order to set the appropriate distance L according to the conditions, the connecting components 131, 132 of the induction heating device 100 may include a movable portion that enables at least one of the conductor components 110, 120 to move in the through-plate direction of the metal strip S. As an example of the movable portion of the present disclosure, it is also possible to use Fig.12 and Fig.13 The movable part 150 is provided on the connecting parts 131 and 132 (in Fig.12 and Fig.13The invention only describes the multiple bolt holes of the connecting member 131. The multiple bolt holes are provided in the connecting members 131 and 132 at intervals in the direction of the plate. By changing the installation positions of the conductor members 110 and 120, specifically, by changing the installation positions of the conductor members 110 and 120 by means of the bolts 152, the distance between the conductor members 110 and 120 can be changed. For example, if the conductor members 110 and 120 are moved from Fig.12 Move to the position shown Fig.13 When the installation position of the conductor components 110 and 120 is changed, the distance between the conductor components 110 and 120 is changed from the distance L1 to the distance L2. Fig.12 The movement of the conductor components 110 and 120 becomes simple.

[0072] In addition, as another example of the movable part of the present disclosure, it is also possible to use Fig.14A and Fig.15 The movable part 160 is a connecting part 131 and 132 (in the embodiment of FIG. 1 ) that connects the conductor parts 110 and 120, respectively. Fig.12 and Fig.13 Only the telescopic part of the connecting member 131 is described. The telescopic part is composed of a flexible conductor such as a braided wire. Fig.15 As shown in FIG. 1 , the expansion and contraction portion constitutes the central portion of the connecting members 131 and 132 in the direction of passing through the plate. Specifically, the plate portions 131A and 132A of the connecting members 131 and 132 connected to the conductor members 110 and 120 are connected. Fig. 14B As shown, the expansion and contraction portion is bent in a mountain shape toward the side opposite to the metal strip S. Fig.15 As shown, the curved telescopic portion moves the position of the conductor components 110 and 120 in the direction of passing through the plate by telescoping. In addition, when the position of the conductor components 110 and 120 in the direction of passing through the plate is changed, the movement of the conductor components 110 and 120 is simplified by arranging rollers or the like below the conductor components 110 and 120. In addition, the flexible conductor constituting the telescopic portion may be used as a water cooling cable.

[0073] [Formula 6]

[0074]

[0075] In addition, regarding the frequency f [kHz] of the AC current, according to the results of analysis performed by the inventors of the present application, the range D [mm] from the edge where 70% of the input power contributes to the temperature rise is expressed by the relationship with the induced current I, for example, as shown in the following equation (9).

[0076] [Formula 7]

[0077] D=-15×ln(f)+107[mm] (9)

[0078] According to the structure of the first embodiment of the present disclosure, the entire width direction of the metal strip S is heated only during the period when it passes under (or above) the conductor members 110 and 120 of the induction heating device 100. Moreover, between the conductor members 110 and 120, the heating range is limited to the width direction end SE of the metal strip S. Thus, input power can be saved and unnecessary influence on the metal structure can be avoided. That is, in the present embodiment, the width direction end SE of the metal strip S can be effectively heated to prevent the end of the metal strip S from being broken during cold rolling. In addition, in the above-mentioned structure, since there is no component that must be arranged close to the width direction end SE of the metal strip S as the heating part, and the surrounding current is formed by the induced current generated during the period when it passes under (or above) the conductor members 110 and 120, it is possible to cope with the meandering of the width direction of the metal strip S and the change of the plate width and plate thickness without changing the arrangement of the components, and even if the metal strip S has a shape defect, it can be heated.

[0079] Here, the end of the metal strip is broken, for example, in the pickling process or the cold rolling process after the hot rolling process. Therefore, the induction heating device 100 can be used in the pickling device 500 (see Fig. 20 ) is arranged in the front section of the pickling device 500, and can also be arranged in the cold rolling device 510 (refer to Fig.21 ) is arranged in the front section of the cold rolling device 510. In addition, the end of the metal strip is cracked, for example, in the molten metal coating process. Therefore, the induction heating device 100 can also be Fig. 22 The processing equipment shown in the figure, including a plating tank 520, a cleaning device 522, and an alloying heating device 524, is arranged between the cleaning device 522 and the alloying heating device 524. The plating tank 520 accumulates molten metal M (for example, molten zinc); the cleaning device 522 blows gas (for example, air) to the metal strip S to which the molten metal M is attached; the alloying heating device 524 heats the molten metal M attached to the metal strip S to an alloying temperature, and maintains the temperature to alloy it.

[0080] (Second embodiment)

[0081] Figure 41 is a top view of an induction heating device for a metal strip according to a second embodiment of the present disclosure. As shown in the figure, the induction heating device 200 according to the present embodiment is composed of a parallel circuit including conductor components 110A, 120A and connecting components 131A, 232A forming a primary closed circuit 101A, conductor components 110B, 120B and connecting components 131B, 232B forming a primary closed circuit 101B, and an AC power source 240. The primary closed circuits 101A and 101B are connected in the through-plate direction of the metal strip S (in the direction of the metal strip S). Figure 4 In each of the primary closed circuits 101A and 101B, the structures of the conductor components 110A, 110B and the conductor components 120A, 120B are respectively the same as the conductor components 110, 120 of the first embodiment described above. The conductor component 120A constituting the primary closed circuit 101A and the conductor component 110B constituting the primary closed circuit 101B are disposed adjacent to each other in the direction of passing the metal strip S, and currents of the same phase are passed through them.

[0082] In the plan view, the connection members 131A and 131B respectively connect the conductor members 110A and 120A and the conductor members 110B and 120B to each other at a position away from the width direction end SE of the metal strip S to form the primary closed circuit 101A and 101B. The connection members 232A and 232B respectively connect the conductor members 110A and 120A and the conductor members 110B and 120B to each other at a position away from the width direction end SE of the metal strip S by a distance E to form the primary closed circuit 101A and 101B, and connect the primary closed circuit 101A and 101B in parallel with the AC power source 240. The AC power source 240 is connected to the primary closed circuit 101A and 101B so that the AC current of the same phase flows through the conductor members 120A and 110B, which are adjacent to each other in the sheet passing direction of the metal strip S.

[0083] According to the structure of the second embodiment of the present disclosure, in addition to obtaining the same effects as the first embodiment, an appropriate distance L can be set as the total value of the primary closed circuits 101A and 101B. Thus, when the primary closed circuits 101A and 101B are connected in parallel, the inductance of each primary closed circuit can be reduced to about half compared to the case where the distance L is set in a single primary closed circuit. In addition, by passing the same-phase alternating current through the mutually adjacent conductor parts 120A and the conductor parts 110B, the magnetic flux generated around each conductor part is in the same direction, and the magnetic flux is easily concentrated on the metal strip S.

[0084] Specifically, when a primary closed circuit 101A (inductance L1, impedance Z1) composed of one group of conductor components 110A and 120A is connected in parallel with a primary closed circuit 101B (inductance L2, impedance Z2) composed of another group of conductor components 110B and 120B, the parallel composite inductance L is calculated by the following formula (10).

[0085] L=L1×L2 / L1+L2…(10)

[0086] Generally, if the inductance L1 and the inductance L2 are connected in parallel, the inductance can be reduced. If the inductance L1 and the inductance L2 are substantially equal, then according to the above formula (10), the inductance is substantially halved.

[0087] In particular, when the metal strip S (usually a thinner material) is passed through the plate at a high speed and sufficient heating time cannot be obtained, the distance between the conductor components of a group becomes longer, the inductance and impedance become larger, the burden on the power supply such as high voltage becomes greater, and the equipment cost increases or safety problems occur.

[0088] By connecting in parallel, the inductance can be reduced even if the required phase separation length is long, so that the power supply load can be reduced and the safety issues associated with the increase in voltage can be solved.

[0089] Even when a large power is input without increasing the separation distance, the heat generation of one set of conductor components can be reduced due to the current diversion, thereby improving efficiency.

[0090] Furthermore, as described below, the resonance frequency f of the current is increased.

[0091] [Formula 8]

[0092]

[0093] In addition, L is the inductance [H], and C is the capacitor capacitance [F].

[0094] If the resonance frequency is increased, the heating range of the width direction end portions SE of the metal strip S can be narrowed, and the width direction end portions SE in a limited range can be heated efficiently.

[0095] Figure 51 is a top view of an induction heating device for a metal strip according to another example of the second embodiment of the present disclosure. As a difference from the above-mentioned example, in the illustrated example, the connecting parts 232C and 232D connect the primary closed circuits 101A and 101B in series with the AC power source 240. The same is true for the conductor parts 120A and 110B adjacent to each other in the direction of passing the metal strip S, where the AC current of the same phase is passed through. By connecting the primary closed circuits 101A and 101B in series, the magnitude of the current flowing into each primary closed circuit can be made the same. In addition, by increasing the inductance, the oscillation condition can be changed.

[0096] Specifically, in the case of series connection, the combined inductance L is expressed by the following equation.

[0097] L=L1+L2…(12)

[0098] The series connection increases the inductance and can reduce the frequency.

[0099] If the frequency can be lowered, the penetration depth δ of the current can be deepened, so that the heating range in the thickness direction can be expanded, especially in the case of thick materials, and the heating range from the width direction end SE of the metal strip S can also be expanded.

[0100] [Formula 9]

[0101]

[0102] In addition, ρ is the resistivity [μΩcm], μr is the specific magnetic permeability, and f is the frequency [Hz].

[0103] Furthermore, since the currents flowing through all the conductor members are the same, the amount of edge heating of each closed circuit can be made the same even if the impedances are different.

[0104] As described above, if parallel / series connection can be performed freely, the required appropriate frequency, current / power distribution, and heating range of the width end of the metal strip can be changed relatively freely according to the load, which has the advantage of not having to prepare multiple separate devices.

[0105] Generally, when the plate thickness is thin, the plate passing speed is fast, and the temperature change of resistivity is small (SUS304, etc.), since the impedance change before and after heating is small and the power / current is large, a parallel connection that can reduce the heat generation of the conductor is preferred. In the case of ordinary steel with a large temperature change of resistivity, when there is an impedance difference before and after heating, or in the case of thick steel with a slow plate passing speed, the current amount between the circuits becomes the same, and a series connection with a larger inductance and easier heating on the low-frequency side is preferred.

[0106] The induction heating device 200 may manually switch between the series connection and the parallel connection of the primary closed circuits 101A and 101B, but may also include a switching circuit that automatically switches between them. Figure 4 The connecting parts 232A, 232B or Figure 5 A switch is provided to selectively connect one of the connection components 232C and 232D to the AC power source 240. As an example, a Fig.18 and Fig.19 The switches 201A and 201B shown are used to switch the parallel connection ( Fig.18 connection) and series connection ( Fig.19 ). Fig.18 In the embodiment, the contact A of the switch 201A connected to the conductor component 120A and the contact B of the conductor component 110B are short-circuited. In addition, the contact D of the switch 201B connected to the connection component 232A and the contact E connected to the connection component 232B are short-circuited. Thus, the primary closed circuit 101A and the primary closed circuit 101B are connected in parallel. On the other hand, in Fig.19 In the embodiment, the contact A of the switch 201A connected to the conductor member 120A is released from the contact B of the conductor member 110B. Then, the contact D of the switch 201B connected to the connection member 232A and the contact C connected to the conductor member 110B are short-circuited, so that the primary closed circuit 101A and the primary closed circuit 101B are connected in series.

[0107] (Third embodiment)

[0108] Fig. 6A and Figure 6B 2 is a cross-sectional view for illustrating the third embodiment of the present disclosure. Fig. 6A As shown, in this embodiment, magnetic cores 351, 352, 361, 362 are arranged on the surface of the plate portions 111, 112, 121, 122 constituting the conductor member on the opposite side to the metal strip S. Figure 6BCompared with the case where no magnetic core is arranged as shown, the magnetic flux freely circulating on the opposite side of the metal strip S of the plate parts 111, 112, 121, 122 constituting the conductor member passes through the magnetic cores 351, 352, 361, 362 with high magnetic permeability, so that the magnetic flux easily enters the metal strip S directly below the conductor parts 111, 112, 121, 122, and the metal strip S can be more effectively inductively heated. In this embodiment, by arranging the magnetic core as described above, the magnetic flux generated by the current flowing through the conductor can be concentrated on the plate parts 111, 112, 121, 122 of the conductor member, so that the gap with the metal strip S can be increased, for example, to correspond to the wave shape in the thickness direction of the metal strip S. In addition, in this embodiment, by arranging the magnetic core, the leakage magnetic flux toward the back side (the side not facing the metal strip S) of the conductor member is reduced, so that, for example, the member supporting the conductor member and the equipment arranged in the periphery can be prevented from being heated.

[0109] The magnetic core only needs to ensure an appropriate cross-sectional area to prevent magnetic saturation. For example, when using high frequencies, even if the saturation magnetic flux density is small, a ferrite core with a small cross-sectional area is sufficient. In addition, if the frequency is low, a laminated electromagnetic steel plate with a large saturation magnetic flux density, amorphous (amorphous) and other ferromagnetic materials can be used. In addition, if heat generation is a concern, it is preferred to appropriately set up a cooling device such as a water-cooled copper plate to cool the magnetic core.

[0110] Fig. 7A and Figure 7B It is a cross-sectional view for explaining another example of the third embodiment of the present disclosure. Figure 7B The plate parts 111A, 111B, 112A, 112B, 121A, 121B, 122A, 122B which constitute the conductor parts are constituted only, but in the case of a separate closed circuit Figure 6B In this case, since the magnetic flux is freely radiated in the front-to-back direction of the traveling direction of the metal strip S (the same as the passing direction of the strip), the magnetic flux is not easily concentrated. In contrast, in another example of the third embodiment, when the same-phase current flows through the plate portions 111A, 111B, 112A, and 112B in the center of the two closed circuits, the magnetic flux generated in the plate portions 111A, 111B, 112A, and 112B does not narrow the range in which it can propagate in the front-to-back direction in the length direction of the metal strip S (the same as the passing direction of the strip) due to the reverse-phase magnetic flux generated in the plate portions 111A, 112A, 121B, and 122B. The magnetic flux is confined to the vicinity of the plate portions 111A, 111B, 112A, and 112B, resulting in the effective concentration of the induced current. Fig. 7AAs shown, in the present embodiment, if magnetic cores 351, 352, 361, 362, 371, 372 are arranged on the surface of the plate portions 111A, 111B, 112A, 112B, 121A, 121B, 122A, 122B constituting the conductor component on the opposite side to the metal strip S, the induced current can be concentrated more effectively. Here, the magnetic cores 371 and 372 only need to be close to each other, and may be divided in the middle of the length direction / width direction, but it is preferable to arrange them in common with two plate portions 121A, 111B and plate portions 122A, 122B of the conductor component that are adjacent in the through-plate direction of the metal strip S. That is, the magnetic core 371 covers the back sides of both the plate portions 121A and 111B of the conductor component, and the magnetic core 372 covers the back sides of both the plate portions 122A and 112B of the conductor component. As a result, for example, even in the above-mentioned Figure 4 and Figure 5 In the case where a plurality of primary closed circuits are arranged adjacent to each other in the through-plate direction of the metal strip S as shown in the example Figure 7B Compared with the case where no magnetic core is provided, magnetic flux can more easily enter the metal strip S. As a result, the metal strip S can be more effectively inductively heated. The fact that the gap between the conductor member and the metal strip S can be increased and the leakage magnetic flux can be reduced is also the same as the above example.

[0111] (Fourth embodiment)

[0112] Fig. 8A is a top view of an induction heating device for a metal strip according to a fourth embodiment of the present disclosure. Fig. 9 is equivalent to Fig. 8A 9-9 line view of the induction heating device shown. As shown in the figure, the induction heating device 400 related to this embodiment includes conductor parts 110, 120 and connecting parts 132, 431 that form a primary closed circuit 101, and an AC power supply 140. As a difference from the first embodiment described above, in this embodiment, at the end side of the metal strip S, the connecting parts 431 and 132 are arranged on the upper surface or the lower surface thereof in a manner that does not interfere with the metal strip S in the thickness direction of the metal strip S. Specifically, for example Fig. 9 As shown in the example, the plate portions 111, 121 of the conductor component are connected on the surface side of the metal strip S, and the plate portions 112, 122 of the conductor component are connected on the back side by connecting components 431, respectively, and no conductor component is connected between the surface side and the back side of the metal strip S.

[0113] According to the fourth embodiment of the present disclosure, in addition to obtaining the same effects as the first embodiment, when it is necessary to remove the induction heating device 400 from the conveyor line of the metal strip S for maintenance, it only needs to be pulled downward (power supply side) in the figure. Even during operation, there is no need to stop / cut off the metal strip S in conveyance, and maintenance can be easily carried out.

[0114] In the above-mentioned embodiment, the connection members 131 and 132 are separated from the width direction end SE of the metal strip S, but the present disclosure is not limited to this structure. Figure 8B As shown, the connecting member may overlap with the width direction end SE of the metal strip S in a top view (for example, it may overlap by several tens of mm). Specifically, above and below the conductor members 110 and 120, the connecting member is arranged so as to partially overlap with the width direction end SE of the metal strip S in a top view relative to the maximum plate width of the heated material to be processed. By making such a structure, it is possible to avoid contact between the connecting member and the width direction end of the metal strip S. In addition, the width dimension of the connecting member may be greater than the width dimension of the conductor members 110 and 120. By making such a structure, even if the metal strip S is conveyed in a meandering manner, the current can flow evenly in the width direction end SE of the metal strip S.

[0115] In addition, in the above-mentioned embodiment, a thin metal strip S is used as the metal plate, but the present disclosure is not limited to this. A thick metal such as a thick plate or a slab can also be used as the metal plate. In this case, the effect of the present disclosure can be obtained in the same manner as in the first embodiment. In addition, the case where the heated part moves is illustrated, but it can also be applied in a stationary state. Fig.17 In the figure, the induction heating device disclosed in the present invention (refer to Fig.16 ) The flow of current on the side of thick metal in a state where the current flows to the thick metal.

[0116] (Verification of heating effect)

[0117] Fig.10 and Fig.11 is a graph showing the analysis results for verifying the effect of heating the widthwise end portions of a metal strip in the embodiment of the present disclosure. Figures 1 to 3 The described induction heating device performs electromagnetic field analysis based on the finite element method under the following conditions to calculate the ratio of the temperature Tc of the width center portion of the metal strip to the temperature Te of the width end portion and the temperature of the width end portion (edge ​​temperature).

[0118] ·Metal strip width W = 1200mm

[0119] ·Metal strip thickness t=2mm

[0120] Width of conductor part B = 200 mm

[0121] Frequency of AC current f = 10kHz

[0122] ·AC current = 10kA

[0123] · The distance between the conductor parts L = variable between 200mm and 600mm

[0124] The temperature of the metal strip before heating is T0 = 0°C

[0125] In the above analysis, when the distance L between the conductor parts is set to the minimum (100 mm), the ratio L / B of the width B of the conductor part and the distance L is 1. Fig.10 As shown in the graph of , in the range where the ratio L / B is greater than 1, the temperature Te of the widthwise end of the metal strip is significantly higher than the temperature Tc of the central portion. Fig.11 As shown in the graph, the edge temperature is low when the ratio L / B is in the range of 1 to 2, but if the ratio L / B exceeds 2, the edge temperature exceeds 50°C, and the edge temperature rises as the ratio L / B increases. The ratio L / B exceeding 2 (L / B>2) and the distance L exceeding the total width of the two conductor parts (L>2B) are equivalent. Under such conditions, the induction heating device can effectively heat the end of the metal strip in the width direction.

[0126] The above, while referring to the attached Figure 1 While the preferred embodiments of the present disclosure are described in detail, the present disclosure is not limited to these examples. Obviously, as long as one is skilled in the art in the technical field to which the present disclosure belongs, various variations or modifications can be thought of within the scope of the technical concept described in the claims, and it should be understood that the above also naturally belong to the technical scope of the present disclosure.

[0127] Regarding the above-mentioned embodiment, the following supplementary notes are also disclosed.

[0128] (Note 1)

[0129] An induction heating device for a metal plate comprises: a first conductor component, which is opposite to at least one of the surface and the back surface of the metal plate and is arranged across the metal plate in the width direction; a second conductor component, which is separated from the first conductor component by a first distance in the through-plate direction of the metal plate, is opposite to at least one of the surface and the back surface of the metal plate and is arranged across the metal plate in the width direction; a connecting component, which connects the first conductor component and the second conductor component to each other to form a primary closed circuit; and an AC power supply connected to the primary closed circuit, the first distance being greater than the total value of the dimensions of the first conductor component and the second conductor component in the through-plate direction of the metal plate.

[0130] (Note 2)

[0131] In the induction heating device according to Supplementary Note 1, the first conductor member and the second conductor member are arranged to face each other on the same side of the metal plate.

[0132] (Note 3)

[0133] In the induction heating device according to Supplementary Note 2, the first conductor member and the second conductor member are arranged on the front side and the back side of the metal plate, respectively.

[0134] (Note 4)

[0135] In the induction heating device for a metal plate as described in any one of Notes 1 to 3, the first primary closed circuit and the second primary closed circuit respectively formed by the first conductor component, the second conductor component and the connecting component are arranged adjacent to each other in the direction of the metal plate passing through the plate; the AC power supply supplies AC current of the same phase to the adjacent conductor components in the first primary closed circuit and the second primary closed circuit in the direction of the metal plate passing through the plate.

[0136] (Note 5)

[0137] The induction heating device for a metal plate as described in Supplementary Note 4 further includes a switching circuit capable of switching between series connection and parallel connection of the first primary closed circuit and the second primary closed circuit.

[0138] (Note 6)

[0139] The induction heating device for a metal plate according to any one of Supplementary Notes 1 to 5 further comprises a magnetic core arranged on a surface of at least one of the first conductive member and the second conductive member on the opposite side to the metal plate.

[0140] (Note 7)

[0141] As the induction heating device for a metal plate according to any one of Supplementary Notes 1 to 6, the connecting member is arranged on at least one side in the width direction of the metal plate so as not to interfere with the metal plate in the thickness direction of the metal plate.

[0142] (Note 8)

[0143] In the induction heating device for a metal plate according to any one of Supplementary Notes 1 to 7, the connecting member includes a movable portion capable of moving at least one of the first conductive member and the second conductive member in a passing direction of the metal plate.

[0144] (Note 9)

[0145] A metal plate processing equipment comprises: a metal plate pickling device; and an induction heating device for the metal plate according to any one of Supplementary Notes 1 to 8, which is arranged in the front stage of the pickling device.

[0146] (Note 10)

[0147] A metal plate processing equipment comprises: a metal plate cold rolling device; and an induction heating device for the metal plate according to any one of Supplementary Notes 1 to 8, which is arranged at a front stage of the cold rolling device.

[0148] (Note 11)

[0149] A metal plate processing equipment comprises: a cleaning device for blowing gas to a metal plate with molten metal attached thereto; an alloying heating device for alloying the molten metal attached to the metal plate by heating; and an induction heating device for the metal plate described in any one of Notes 1 to 8, which is arranged between the cleaning device and the alloying heating device.

[0150] (Note 12)

[0151] A method for induction heating of a metal plate, comprising: a process of passing an alternating current through a primary closed circuit formed by a first conductor component, a second conductor component and a connecting component, wherein the first conductor component is opposite to at least one of the surface and the back surface of the metal plate and is arranged across the metal plate in the width direction; the second conductor component is opposite to at least one of the surface and the back surface of the metal plate, is separated from the first conductor component by a first distance in the direction of passing the metal plate, and is arranged across the metal plate in the width direction; the connecting component connects the first conductor component and the second conductor component to each other; and a process of induction heating the width direction end portions of the metal plate by passing a secondary closed circuit formed by an induced current generated in regions of the metal plate respectively opposite to the first conductor component and the second conductor component through the width direction end portions of the metal plate.

[0152] (Note 13)

[0153] An induction heating device for a metal strip comprises: a first conductor component, which is opposite to the surface or back side of the metal strip and is arranged across the metal strip in the width direction; a second conductor component, which is separated from the first conductor component by a first distance in the through-plate direction of the metal strip, is opposite to the surface or back side of the metal strip and is arranged across the metal strip in the width direction; a connecting component, which connects the first conductor component and the second conductor component to each other at a position away from the width-direction end of the metal strip to form a primary closed circuit; and an AC power supply connected to the primary closed circuit, the first distance being greater than the total value of the dimensions of the first conductor component and the second conductor component in the through-plate direction of the metal strip.

[0154] (Note 14)

[0155] In the induction heating device for a metal strip as described in Note 13, the first primary closed circuit and the second primary closed circuit respectively formed by the first conductor component, the second conductor component and the connecting component are arranged adjacent to each other in the passing direction of the metal strip; the AC power supply supplies AC current of the same phase to the adjacent conductor components in the first primary closed circuit and the second primary closed circuit in the passing direction of the metal strip.

[0156] (Note 15)

[0157] The induction heating device for a metal strip as described in Supplementary Note 14 further includes a switching circuit capable of switching between series connection and parallel connection of the first primary closed circuit and the second primary closed circuit.

[0158] (Note 16)

[0159] The induction heating device for a metal strip as described in any one of Supplementary Notes 13 to 15 further includes a magnetic core arranged on a surface of at least one of the first conductive member and the second conductive member on the opposite side to the metal strip.

[0160] (Note 17)

[0161] As in the induction heating device for a metal strip as described in any one of Supplementary Notes 13 to 16, the connecting member is arranged on at least one side in the width direction of the metal strip so as not to interfere with the metal strip in the thickness direction of the metal strip.

[0162] (Note 18)

[0163] In the induction heating device for a metal strip as described in any one of Supplementary Notes 13 to 17, the connecting member includes a movable portion capable of moving at least one of the first conductor member and the second conductor member in a passing direction of the metal strip.

[0164] (Note 19)

[0165] A metal strip processing equipment comprises: a pickling device for the metal strip; and an induction heating device for the metal strip as described in any one of Notes 13 to 18, which is arranged in the front section of the pickling device.

[0166] (Note 20)

[0167] A metal strip processing equipment comprises: a metal strip cold rolling device; and an induction heating device for the metal strip as described in any one of Notes 13 to 18, which is arranged in the front section of the above-mentioned cold rolling device.

[0168] (Note 21)

[0169] A method for induction heating of a metal strip, comprising: a process of passing an alternating current through a primary closed circuit formed by a first conductor component, a second conductor component and a connecting component, wherein the first conductor component is opposite to the surface or back surface of the metal strip and is arranged across the metal strip in the width direction; the second conductor component is opposite to the surface or back surface of the metal strip, is separated from the first conductor component by a first distance in the passing direction of the metal strip, and is arranged across the metal strip in the width direction; the connecting component connects the first conductor component and the second conductor component to each other at a position away from the width end of the metal strip; and a process of induction heating the width end of the metal strip by passing a secondary closed circuit formed by induced current generated in the metal strip in the regions respectively opposite to the first conductor component and the second conductor component through the width end of the metal strip.

[0170] According to the above structure, the entire width direction of the metal strip is heated only when it passes under (or above) the conductor member, and the heating range is limited to the width direction end of the metal strip between the conductor members. As a result, the width direction end of the metal strip can be effectively heated to prevent the end of the metal strip from being broken. In addition, since the interval between the induction coil and the heated object can be ensured to be relatively large, deformation, meandering, etc. of the heated object can be easily handled without additional equipment.

[0171] Description of symbols

[0172] 100, 200, 400…induction heating device; 101, 101A, 101B…primary closed circuit; 102…secondary closed circuit; 110, 110A, 110B, 120, 120A, 120B…conductor component; 131, 131A, 131B, 132, 232A, 232B, 232C, 232D, 431…connecting component; 140, 240…AC power supply; 351, 352, 361, 362, 371, 372…magnetic core; 500…pickling device; 510…cold rolling device; 522…cleaning device; 524…alloying heating device; S…metal strip.

Claims

1. An induction heating device for a metal plate, have: A first conductor member is arranged to face at least one of the front surface and the back surface of the metal plate and to straddle the metal plate in the width direction; The second conductor member is arranged to be separated from the first conductor member by a first distance in the through-plate direction of the metal plate, to face at least one of the front surface and the back surface of the metal plate, and to cross the metal plate in the width direction; a connecting member that connects the first conductor member and the second conductor member to each other at a position away from the widthwise end of the metal plate to form a primary closed circuit; and An AC power source is connected to the above primary closed circuit. The first distance is larger than a total value of dimensions of the first conductor member and the second conductor member in a direction extending through the metal plate.

2. The induction heating device according to claim 1, The first conductor member and the second conductor member are arranged to face each other on the same side of the metal plate.

3. The induction heating device according to claim 2, The first conductor member and the second conductor member are disposed on the front surface side and the back surface side of the metal plate, respectively.

4. The induction heating device for a metal plate according to any one of claims 1 to 3, The first primary closed circuit and the second primary closed circuit respectively formed by the first conductor component, the second conductor component and the connecting component are arranged adjacent to each other in the through-plate direction of the metal plate. The AC power source supplies AC currents of the same phase to the conductor parts adjacent to each other in the direction in which the metal plate passes through the plate in the first primary closed circuit and the second primary closed circuit.

5. The induction heating device for a metal plate according to claim 4, The device further includes a switching circuit capable of switching between series connection and parallel connection of the first primary closed circuit and the second primary closed circuit.

6. The induction heating device for a metal plate according to any one of claims 1 to 5, A magnetic core is further provided. The magnetic core is arranged on a surface of at least one of the first conductive member and the second conductive member, which surface is opposite to the metal plate.

7. The induction heating device for a metal plate according to any one of claims 1 to 6, The connecting member is disposed on at least one side in the width direction of the metal plate so as not to interfere with the metal plate in the thickness direction of the metal plate.

8. The induction heating device for a metal plate according to any one of claims 1 to 7, The connecting member includes a movable portion capable of moving at least one of the first conductive member and the second conductive member in a direction in which the metal plate passes.

9. A metal plate processing device, include: Pickling plants for metal sheets; as well as The induction heating device for metal plates according to any one of claims 1 to 8 is arranged in the upstream stage of the pickling device.

10. A metal plate processing device, include: Cold rolling equipment for metal sheets; as well as The induction heating device for metal plates according to any one of claims 1 to 8 is arranged in the upstream stage of the cold rolling device.

11. A metal plate processing device, include: A cleaning device for blowing gas to the metal plate to which the molten metal is attached; an alloying heating device for alloying the molten metal attached to the metal plate by heating; as well as The induction heating device for a metal plate according to any one of claims 1 to 8 is arranged between the cleaning device and the alloying heating device.

12. A method for induction heating of a metal plate, Including the following processes: For a primary closed circuit formed by a first conductor member, a second conductor member, and a connecting member, an alternating current is passed through the circuit, wherein the first conductor member is arranged to face at least one of the front surface and the back surface of the metal plate and straddles the metal plate in the width direction, the second conductor member is arranged to face at least one of the front surface and the back surface of the metal plate and is separated from the first conductor member by a first distance in a direction through which the metal plate passes and straddles the metal plate in the width direction, and the connecting member connects the first conductor member and the second conductor member to each other at a position separated from an end portion in the width direction of the metal plate; and A secondary closed circuit formed by an induced current generated in the metal plate in regions facing the first conductor member and the second conductor member passes through the widthwise end portions of the metal plate, thereby inductively heating the widthwise end portions of the metal plate.

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