JP7124515B2 - Induction heating equipment for metal strips - Google Patents

Description

The present invention relates to induction heating equipment for metal strips.

Induction heating is a heating method that uses the principle of electromagnetic induction to generate eddy currents in the object to heat the object using Joule heat, and is widely used because of its low heat loss and high efficiency. . There are two main methods for induction heating of metal strips. One method is to apply a high-frequency current to an induction coil that surrounds the metal strip in the width direction, causing magnetic flux to flow in the longitudinal direction of the metal strip. LF (Longitudinal Flux induction heating) method (hereinafter referred to as LF method). In the other method, a metal strip is placed between the induction coils (good conductors) around which the primary coil is wound, and the magnetic flux generated by passing current through the primary coil is passed through the surface of the metal strip. and a TF (Transverse Flux induction heating) method (hereinafter referred to as a TF method) in which an induced current is generated on the plate surface of the metal strip to heat the metal strip.

When a metal strip is induction-heated, the main body of the induction heating device may be made of a non-magnetic material such as stainless steel or copper that is difficult to heat, and may be cooled using cooling equipment such as water cooling. On the other hand, since the magnetic flux generated by the induction heating device also leaks to the outside of the induction heating device, unintended induction heating may occur in the metal parts around the induction heating device due to the penetration of this leakage magnetic flux. be. To address this problem, for example, in Patent Document 1, in a TF type induction heating device, an induction heating device and A technique of arranging an electromagnetic shield plate for shielding between the conveying roller is described. Further, in Patent Document 2, in an LF type induction heating device, a shielding plate made of a diamagnetic conductive band is used to prevent induction heating of metal such as a supporting machine and a floor of the induction heating device. A technique is described in which the magnetic flux is confined inside the shield plate by covering the outside of the shield.

JP-A-64-57587 Japanese Utility Model Laid-Open No. 3-76392

The technology described in Patent Document 1 and Patent Document 2 is intended to prevent members such as a conveying roller from being induction-heated outside the induction heating device. It does not address the inductive heating of the plate. This is because the metal strip is intended to be heated by an induction heating device, and therefore it was thought that there would be no problem even if it was induction heated outside the induction heating device. However, in recent years, the heating temperature control of the metal strip in the induction heating device has become more precise, and the magnetic flux for heating the metal strip inside the induction heating device is often finely controlled. In such a case, if the metal strip is induction-heated by the leaked magnetic flux outside the induction heating device, it becomes difficult to achieve desired heating temperature control.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a new and improved induction heating facility for metal strips, which can effectively prevent the metal strips from being heated outside the induction heating apparatus. do.

According to one aspect of the present invention, an induction heating device for heating a metal strip that is continuously conveyed, and an induction heating device disposed on at least one of the inlet side and the delivery side of the induction heating device, and the width direction of the metal strip An induction heating facility for a metal strip is provided, comprising: a magnetic shielding member including portions spaced apart and opposed to at least one plate surface of a region including an end portion.
According to the above configuration, since the magnetic flux leaking to the outside of the induction heating device is blocked by the magnetic shielding member before passing through the metal strip, it is possible to prevent the metal strip from being induction-heated outside the induction heating device. can be effectively prevented. Further, if the leakage magnetic flux is interrupted on the output side of the induction heating device, the influence of the heating temperature due to the leakage magnetic flux further added to the temperature distribution controlled by the induction heating device can be eliminated. The temperature distribution due to induction heating in the induction heating device is generally high at the ends of the metal strip in the width direction in the case of a thin plate. It is possible to prevent overheating due to further induction heating of both ends of the strip by leakage magnetic flux.

In the above induction heating equipment, the magnetic shielding member may be provided across the width direction of the metal strip.
In this case, it is possible to prevent induction heating of the metal strip due to leakage magnetic flux over the entire width of the metal strip.

In the above-described induction heating equipment, the magnetic shielding member may include portions that face at least one widthwise edge of the metal strip while being spaced apart from each other.
In this case, leakage magnetic fluxes in various directions near the edges in the width direction of the metal strip can be blocked.

The induction heating equipment may further include a magnetic core disposed between the magnetic shielding member and the metal strip, insulated from the magnetic shielding member and separated from the metal strip.
In this case, not only the leakage magnetic flux of the induction heating device but also the induced current generated in the induction heating device may flow outside the induction heating device. It is possible to greatly reduce the flow of the induced current generated in the plate to the outside of the induction heating device, and to more effectively prevent the metal strip from being heated outside the induction heating device.

It is a side view of induction heating equipment concerning a 1st embodiment of the present invention. It is a top view of induction heating equipment concerning a 1st embodiment of the present invention. It is a side view of the induction heating equipment which concerns on the 2nd Embodiment of this invention. It is a top view of induction heating equipment concerning a 2nd embodiment of the present invention. It is a side view of induction heating equipment concerning a 3rd embodiment of the present invention. It is a top view of induction heating equipment concerning a 3rd embodiment of the present invention. It is a longitudinal cross-sectional view of the induction heating equipment which concerns on the 4th Embodiment of this invention. It is a cross-sectional view of induction heating equipment according to a fourth embodiment of the present invention. It is a top view of induction heating equipment concerning a 5th embodiment of the present invention. It is a cross-sectional view of the induction heating equipment which concerns on the 5th Embodiment of this invention.

Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings. In the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

(First embodiment)
1A and 1B are side and top views of induction heating equipment according to a first embodiment of the present invention. As shown in FIGS. 1A and 1B, induction heating equipment 10 for heating a continuously conveyed metal strip S includes an induction heating device 11 and a magnetic shielding member 12 . The induction heating device 11 is an LF type or TF type induction heating device, and has at least one induction coil for generating magnetic flux. In the case of the LF method, magnetic flux is generated along the longitudinal direction of the metal strip S. Further, in the case of the TF method, magnetic flux is generated in a direction penetrating the plate surface of the metal strip plate S.

In the illustrated example, the magnetic shielding member 12 is a magnetic shielding member 12A arranged on the entrance side of the induction heating device 11, that is, on the side where the continuously conveyed metal strip S enters the induction heating device 11. , and a magnetic shielding member 12B arranged on the delivery side of the induction heating device 11, that is, the side where the metal strip S is pulled out from the induction heating device 11. As shown in FIG. In another example, only one of the entrance-side magnetic shielding member 12A and the exit-side magnetic shielding member 12B of the induction heating device 11 may be arranged. In this embodiment, the magnetic shielding member 12 includes a magnetic shielding plate 121 that faces one side of the metal strip S with a gap, and a magnetic shielding plate 122 that faces the other side of the metal strip S with a gap. including.

The magnetic shielding plates 121 and 122 are made of an alloy containing, for example, non-magnetic copper or aluminum. By arranging the magnetic shielding plates 121 and 122 on at least one surface of the metal strip S, the magnetic flux leaking to the outside of the induction heating device 11 is cut off before penetrating the metal strip S. FIG. Since the magnetic shielding plates 121 and 122 are induction-heated instead of the metal strip S, they may be made of a low-resistance, non-magnetic material with a high melting point, such as copper. A cooling mechanism (not shown) may be provided to cool the induction-heated magnetic shielding plates 121 and 122 . For example, the magnetic shielding plates 121 and 122 may be made of water-cooled copper plates.

As shown in FIG. 1B, in this embodiment, the magnetic shielding plates 121 and 122 are provided across the width direction of the metal strip plate S. As shown in FIG. As a result, it is possible to prevent unintended induction heating of the metal strip S due to leakage magnetic flux in the entire width direction of the metal strip S, and to realize the heating temperature control of the metal strip S by the induction heating device 11 with high accuracy. can. In addition, by blocking the leakage magnetic flux, sparks between the metal strip S and the transport roll due to stray current can be suppressed, thereby preventing the transport roll and the metal strip S from being damaged.

(Second embodiment)
2A and 2B are side and top views of induction heating equipment according to a second embodiment of the present invention. In this embodiment, an induction heating facility 20 includes an induction heating device 11 and a magnetic shielding member 22 similar to those in the first embodiment. The magnetic shielding member 22 includes a magnetic shielding member 22A arranged on the entrance side of the induction heating device 11 and a magnetic shielding member 22B arranged on the exit side of the induction heating device 11 . As in the first embodiment, only one of the magnetic shielding members 22A and 22B may be arranged. In the present embodiment, the magnetic shielding member 22 includes magnetic shielding plates 221 and 222 that are spaced apart from one surface of the metal strip S at both ends of the metal strip S in the width direction, and the metal strip S It includes magnetic shielding plates 223 and 224 which are spaced apart from and face opposite sides of the metal strip S at both ends.

Furthermore, in the present embodiment, the magnetic shielding member 22 includes magnetic shielding plates 225 and 226 that face both edges of the metal strip S with a space therebetween. That is, the magnetic shielding member 22 includes magnetic shielding plates 221, 223, and 225 each having a U-shaped cross section, which are arranged so as to surround both sides and an edge of the metal strip S at one end of the metal strip S, and metal Magnetic shielding plates 222, 224, 226 of U-shaped cross section are arranged to surround both sides and edges of the metal strip S at the other end of the strip S. As shown in FIG. Each of such magnetic shielding plates may be formed of an alloy containing copper or aluminum, for example, as in the first embodiment, or may be formed of a water-cooled copper plate including a cooling mechanism (not shown). .

In this embodiment, the magnetic shielding plates 221 to 226 are arranged only in a partial region including the widthwise end of the metal strip S. As shown in FIG. As a result, it is possible to prevent unintended induction heating of the metal strip S due to leakage magnetic flux in the region including the widthwise end of the metal strip S. For example, when the temperature distribution due to induction heating in the induction heating device 11 is high at the ends of the metal strip S in the width direction, both ends are further induction-heated by leakage magnetic flux to prevent overheating. Therefore, the arrangement of the magnetic shielding plates as in this embodiment is effective. Magnetic shielding plates 225 and 226 are provided at the edges of the metal strip S in the width direction so as to block leakage magnetic flux in various directions near the edges of the metal strip S in the width direction. can be done.

(Third embodiment)
3A and 3B are side and top views of induction heating equipment according to a third embodiment of the present invention. In this embodiment, the induction heating equipment 30 includes a magnetic core 33 in addition to the induction heating device 11 and the magnetic shielding member 12 similar to those of the first embodiment. The magnetic core 33 includes magnetic cores 33A and 33B provided corresponding to the magnetic shielding member 12A and the magnetic shielding member 12B, respectively, and is arranged between the magnetic shielding member 12 and the metal strip S. In the present embodiment, since the magnetic shielding member 12 includes the magnetic shielding plates 121 and 122 that are spaced apart from each other on both sides of the metal strip S, the magnetic core 33 is also positioned between the magnetic shielding plate 121 and the metal strip S. and a magnetic core 332 arranged between the magnetic shielding plate 122 and the metal strip S. The magnetic core 33 is electrically insulated from the magnetic shielding plates 121 and 122 constituting the magnetic shielding member 12 and is separated from the metal strip S. The magnetic core 33 may be coated with insulation.

As in the first embodiment, the magnetic shielding plates 121 and 122 block leakage magnetic flux in this embodiment as well. As a result, the leakage magnetic flux passing through the metal strip S is greatly reduced, but there is a possibility that the magnetic flux flowing along the magnetic shielding plates 121 and 122 will generate an induced current in the metal strip S. FIG. In addition, the induced current generated within the induction heating device may spread outside the induction heating device. The heating of the metal strip S due to such an induced current is smaller than, for example, the induction heating due to leakage magnetic flux in the absence of the magnetic shielding plates 121 and 122, but in the present embodiment, by arranging the magnetic core 33 , the induced current caused by the magnetic flux flowing along the magnetic shielding plates 121 and 122, or the induced current coming out of the induction heating device by increasing the impedance of the magnetic core 33, the induced current that tends to flow in the metal strip S prevent Therefore, in this embodiment, it is possible to more effectively prevent unintended induction heating of the metal strip S due to leakage magnetic flux.

(Fourth embodiment)
4A and 4B are a vertical cross-sectional view and a cross-sectional view of induction heating equipment according to a fourth embodiment of the present invention. In FIGS. 4A and 4B, IVA-IVA line and IVB-IVB line showing the relation of respective cross sections are shown. In this embodiment, the induction heating equipment 40 includes the same induction heating device 11 as in the first embodiment, a magnetic shielding member 42 and a magnetic core 43 . The magnetic shielding member 42 includes a magnetic shielding member 42A arranged on the entrance side of the induction heating device 11 and a magnetic shielding member 42B arranged on the exit side of the induction heating device 11 . The point that only one of the magnetic shielding members 42A and 42B may be arranged is the same as in the above-described third embodiment. In the present embodiment, the magnetic shielding member 42 includes magnetic shielding plates 421 and 422 that are spaced apart from each other on both sides of the metal strip S, and a magnetic shielding plate 423 that is spaced apart from both edges of the metal strip S and faces each other. , 424 are formed in a box-shaped cross-section.

In this embodiment, the magnetic core 43 includes magnetic cores 43A and 43B provided corresponding to the magnetic shielding member 42A and the magnetic shielding member 42B, respectively. It is arranged between the shielding member 42 and the metal strip plate S. As shown in FIG. The magnetic core 43 is electrically insulated from the magnetic shielding plates 421 to 424 and is separated from the metal strip S at the portions along the magnetic shielding plates 421 to 424 . The magnetic core 43 may be coated with insulation. In this embodiment, the magnetic shielding member 42 and the magnetic core 43 are each formed to have a box-shaped cross section surrounding the metal strip S, thereby shielding leakage magnetic flux from each direction, and further along the magnetic shielding member 42 It is possible to prevent the generation of induced current in the metal strip S due to the flowing magnetic flux, or to prevent the induced current coming out of the induction heating device from flowing out of the induction heating device. Therefore, in this embodiment, it is possible to further prevent unintended induction heating of the metal strip S due to leakage magnetic flux.

(Fifth embodiment)
5A and 5B are plan and cross-sectional views of an induction heating facility according to a fifth embodiment of the present invention. FIG. 5B is a cross-sectional view along line VB-VB of FIG. 5A. In this embodiment, the induction heating equipment 50 includes the induction heating device 11 similar to that of the first embodiment, the magnetic shielding member 42 similar to that of the fourth embodiment, and the magnetic core 53 . The magnetic core 53 includes magnetic cores 53A and 53B provided corresponding to the magnetic shielding member 42A and the magnetic shielding member 42B, respectively, and is formed in a shape along the inside of a part of the box-shaped cross section of the magnetic shielding member 42. be. Specifically, the magnetic core 53 includes a magnetic core 531 having a U-shaped cross section, which is disposed so as to surround both sides and an edge of the metal strip S at one end of the metal strip S, and a metal strip A magnetic core 532 having a U-shaped cross section is arranged so as to surround both sides and edges of the metal band plate S at the other end of the plate S. The magnetic core 53 is electrically insulated from the magnetic shielding plates 421 to 424 that make up the magnetic shielding member 42 and is separated from the metal band plate S as in the above embodiment. The magnetic core 53 may be coated with insulation.

In this embodiment, the magnetic core 53 is arranged between the magnetic shielding member 42 and the metal strip S along part of the box-shaped cross section of the magnetic shielding member 42 . The heating of the metal strip S by the induced current caused by the magnetic flux flowing along the magnetic shielding plates 421 to 424 constituting the magnetic shielding member 42 or by the induced current flowing along the edges of the metal strip is compared to the induction heating by leakage magnetic flux. , the magnetic shielding member 42 is not necessarily arranged along the entirety of the magnetic core. Therefore, for example, when the temperature distribution due to induction heating in the induction heating device 11 is high at both ends in the width direction of the metal strip S, as in the example described in the second embodiment, By arranging the magnetic cores 53 shaped as in the present embodiment, unintended heating at both ends of the metal strip S in the width direction may be prevented more effectively. Also, the magnetic cores 531 and 532 may be moved according to the plate width.

It should be noted that, in other embodiments, combinations other than the embodiments described above are also possible with respect to the arrangement of the magnetic shielding member and the magnetic core, for example. For example, the magnetic shielding members 22 arranged at both ends in the width direction of the metal strip S described in the second embodiment may be combined with the magnetic cores 53 described in the fifth embodiment. Further, for example, the box-shaped cross-sectional magnetic shielding member 42 described in the fourth embodiment may be combined with the magnetic core 33 described in the third embodiment. Alternatively, by combining the magnetic shielding member 12 described in the first embodiment and the magnetic core 43 described in the fourth embodiment, the magnetic core is arranged even in a portion where the magnetic shielding member is not arranged. combinations are also possible.

(First embodiment)
Next, examples of the present invention will be described. In the first embodiment, a steel plate of ordinary steel (corresponding to metal strip S, width 1100 mm × thickness 0.8 mm) is held in a stationary state in the horizontal direction, and heated to 1 kHz and 500 kW using a TF induction heating device. and heated so that the central portion of the steel plate reached 600°C. In this case, if the steel sheet is heated by the leaked magnetic flux outside the induction heating apparatus, the heat marks left by heating and oxidation will remain, so the influence of the induced magnetic flux can be verified. Table 1 shows the results of the above verification for Examples 1 to 3 and Comparative Example 1 as described below.

Example 1: A water-cooled copper plate (corresponding to the magnetic shielding plates 121 and 122) having a width of 1200 mm, a length of 900 mm, and a plate thickness of 5 mm was placed at a distance of 150 mm from both sides of the steel plate on the inlet and outlet sides of the induction heating apparatus.
Example 2: A water-cooled copper plate with a thickness of 5 mm (magnetic shielding plate 221 to 224) are placed 150 mm apart from both sides of the steel plate.
Example 3: An electromagnetic steel laminated core (corresponding to the magnetic core 43) of width 1200 mm x height 280 mm x length 100 mm and opening width 1100 mm x height 180 mm was placed inside the same water-cooled copper plate as in Example 1. .
Comparative Example 1: Nothing is installed on the inlet side and the outlet side of the induction heating device.

From the above results, it can be seen that in Comparative Example 1, in which leakage magnetic flux was not dealt with, a distinct W-shaped heating mark was formed, indicating that the steel sheet was induction-heated by leakage magnetic flux. On the other hand, in Example 1, in which a magnetic shielding member made of a water-cooled copper plate that traverses the width direction of the steel plate is installed, although heating marks remain on the side near the induction heating device, they are thin and blurred compared to the comparative example, and leakage magnetic flux is greatly increased. can be blocked. In addition, even in Example 2, in which the water-cooled copper plate was installed only in the region including both ends of the steel plate in the width direction, it was possible to block leakage magnetic flux at both ends of the steel plate in the width direction, as expected. confirmed. In Example 3, the heat mark was further reduced by installing the magnetic core. Since no heat was generated in the core, it was found that leakage magnetic flux was blocked by the water-cooled copper plate, and the magnetic core was effective in preventing the generation of induced current in the steel plate.

From these results, it can be said that the embodiment of the present invention is effective in preventing the metal strip from being heated outside the induction heating apparatus.

(Second embodiment)
In the second example, the same combination of induction heating equipment and steel plate as in Examples 1 to 3 and Comparative Example 1 was used, while continuously conveying the steel plate in the horizontal direction at a speed of 60 m/min. Heating was performed using an induction heating device so that the average temperature of the surface of the steel sheet was raised from normal temperature to 800°C. Example 4 corresponds to Example 1 above, Example 5 corresponds to Example 2 above, Example 6 corresponds to Example 3 above, and Comparative Example 2 corresponds to Comparative Example 1 above. do. A temperature scanner was installed above the delivery side of the induction heating device, and the temperature deviation in the width direction was calculated as a result of measuring the temperature of the entire width of the steel sheet. Note that the temperature deviation is expressed as a ratio (%) to the amount of temperature increase.

In the above results, the temperature deviation with respect to the amount of temperature rise reached ±3.6% in Comparative Example 2, in which leakage magnetic flux was not dealt with. On the other hand, in Example 5 in which the water-cooled copper plate magnetic shielding member was installed only in the region including both ends in the width direction of the steel plate, the temperature deviation was ±3%, which was an improvement of ±0.6%. In Example 4, in which a water-cooled copper plate was installed across the width of the steel plate, the temperature deviation was ±2.6%, which was an improvement of ±1% compared to Comparative Example 2. Furthermore, in Example 6 in which the magnetic core was installed, the temperature deviation was ±2.4%, which was a significant improvement of ±1.2% compared to Comparative Example 2.

From these results, the embodiment of the present invention is effective for reducing the temperature deviation of the metal strip heated by the induction heating device, and therefore for improving the accuracy of the heating temperature control of the metal strip. It can be said that it is effective.

Although the exemplary embodiments of the present invention have been described above, the technical scope of the present invention is not limited to these embodiments. This includes any modified or modified embodiments that may occur to those of ordinary skill in the art.

DESCRIPTION OF SYMBOLS 10, 20, 30, 40, 50... Induction heating equipment, 11... Induction heating apparatus, 12, 22, 42... Magnetic shielding member, 33, 43, 53... Magnetic core, S... Metal strip.

Claims (4)

an induction heating device for heating the continuously conveyed metal strip;
arranged on at least one of the inlet side and the outlet side of the induction heating device, and opposed to at least one plate surface in a region including the width direction end of the metal strip, and a magnetic shielding member including a longitudinally extending plate-like portion. 2. The induction heating equipment for a metal strip according to claim 1, wherein said magnetic shielding member is provided across the width direction of said metal strip. 3. The induction heating equipment for a metal strip according to claim 1, wherein said magnetic shielding member includes a portion facing at least one edge in the width direction of said metal strip while being spaced apart from each other. 4. Any one of claims 1 to 3, further comprising a magnetic core insulated from the magnetic shielding member and spaced apart from the metal strip between the magnetic shielding member and the metal strip. Induction heating equipment for the metal strip according to the above item.

Images