JP2002151245A - Heating method and device of metal base material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide technology for evenly and efficiently heating a strip metal base material by induction heating in width direction. SOLUTION: In induction heating of a strip metal base material 1 while it is conveyed in length direction by a coil 2 for induction heating with the turning face arranged in opposition to a face of the metal base material, the plane shape of the coil at the circumference face is made diamond-shaped with both ends of the longer axis bent, and the coil is made to rotate within the circumference, where, the range of heating is adjusted in accordance with the width of the metal base material by changing slanting angle of the longer axis against the width direction of the metal base material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating method and apparatus for uniformly and efficiently heating a strip-shaped metal substrate in a width direction by induction heating.

[0002]

2. Description of the Related Art Conventionally, various heating methods such as roll heating and infrared heating have been used for heating a strip-shaped metal substrate. In particular, in heating when laminating a metal substrate such as aluminum with a resin film, metal powder or the like of the metal substrate itself is generated and adheres upon contact with a heating roll, and the metal powder is adhered during the lamination. It is necessary to prevent the metal base material from being mixed between the metal base material and the resin film, and to suppress a decrease in the strength of the metal base material due to heating. As a heating method satisfying such requirements, a high-frequency induction heating method capable of heating a metal substrate in a non-contact and short time is known.

[0003] An example of a conventional apparatus for heating a metal substrate by induction heating is described in Document 1: "JP-A-59-3887". According to the technique described in this publication, a plurality of induction heating coils are prepared, and one of the induction heating coils is selected and used according to the width of the metal base to be heated. Thus, induction heating can be performed even when the width of the metal base is changed.

[0004] Another example of the prior art is disclosed in Document 2:
It is described in "Tokuhyo Hei 11-500262". According to the technology described in this publication, a shielding plate is provided between a metal substrate to be heated and an induction heating coil, and the distance between the shielding plates is adjusted so that the heating area is adjusted to the width of the metal substrate. I am adjusting. Thus, induction heating can be performed even when the width of the metal base is changed.

[0005]

However, the above document 1 does not disclose a specific shape of the induction heating coil. Then, when induction heating is performed using a coil which is generally used in the related art and has a rounded rectangular shape with four corners, current concentrates on the side edges of the metal base material.
As a result, there occurs a phenomenon (hereinafter, also referred to as “edge heating”) in which the side edge portion is excessively heated as compared with the vicinity of the center of the metal base material. For this reason, in the conventional coil, it was difficult to uniformly heat the metal substrate.

Further, if the metal base cannot be heated to a uniform temperature in the width direction, the metal base may be bent and may come into contact with a member such as a coil during transportation. Further, for example, when laminating a resin film, the lamination may be incomplete.

Further, in the technique described in Document 1, a large-scale mechanism is required because the coil is exchanged according to the width of the metal base. For this reason, the device configuration becomes large and complicated.

Further, in the technique described in the above-mentioned document 2, it is difficult to bring the coil and the metal base close to each other because the shielding plate is provided. Therefore, it is difficult to increase the heating efficiency. On the other hand, if the coil is too close to the metal base, the shielding plate may come into contact with the metal base being transported. Furthermore, among the magnetic fields generated by the coil, the magnetic field shielded by the shielding plate does not contribute to induction heating of the metal base. Therefore, there is a problem that the heating efficiency is deteriorated. In particular, when the width of the metal base is narrow and the shielding area is wide, the heating efficiency is deteriorated.

The present invention has been made to solve the above-mentioned problem, and has as its object to provide a technique for uniformly and efficiently heating a strip-shaped metal base material in the width direction.

[0010]

According to a first aspect of the present invention, there is provided a method for heating a metal substrate, comprising the steps of: In the method of performing induction heating with coils wound so as to face each other, a method of maximizing the circulating shape of an induced current circulating in a shape similar to or the same as the coil in the transport direction at the center in the width direction of the metal base material is used.

Attention is paid to a certain point of the metal substrate, and the temperature rise at that point is proportional to the integral value of the induced current flowing through that point while the metal substrate is transported near the front of the coil. Then, it is considered that the induced current flowing in the metal base material flows in a shape similar to or the same as the shape of the coil. According to the present invention, by forming the induced current in such a circular shape, the integrated value of the induced current flowing at each point at the end and the center of the metal base material being conveyed is calculated in the width direction of the metal base material. It can be made substantially equal, and the temperature in the width direction can be made uniform.

Further, according to the second aspect of the present invention, there is provided a method for making the integrated value of the induced current circulating in the metal base material being conveyed substantially uniform in the width direction of the metal base material. The amount of temperature rise of each part of the metal substrate due to induction heating is
It is proportional to the integral value of the induced current flowing at that point during transport.
Therefore, if the integrated value is made substantially uniform in each portion in the width direction, the heating temperature in the width direction of the metal base can be made uniform.

According to a third aspect of the present invention, there is provided a method for concentrating or expanding an induced current by partially concentrating or expanding magnetic lines of force generated in a coil and passing through a metal substrate.

According to a fourth aspect of the present invention, there is provided a heating apparatus for performing induction heating while conveying a strip-shaped metal substrate in a longitudinal direction, wherein the coil has a circumferential surface. A coil for induction heating is provided so as to be opposed to the surface of the metal substrate, and the shape of the coil is configured to be the largest at the center in the width direction of the metal substrate in the transport direction of the metal substrate.

Focusing on one point of the metal substrate, the temperature rise at that point is proportional to the integral of the induced current flowing through that point while the metal substrate is transporting near the front of the coil. Then, it is considered that the induced current flowing in the metal base material flows in a shape similar to or the same as the shape of the coil. But,
Since the induced current due to the coil portion protruding from both side edges (edge portion) of the metal base cannot protrude from the metal base,
Current concentrates on the edge of the metal substrate.

For this reason, if the shape of the coil is a rectangular shape in which the orbital portions facing each other across the axis in the width direction of the coil as in the related art are separated by a certain distance, the edge portion of the metal base material is conveyed during transportation. The integral value of the induced current flowing becomes larger than that in the central portion, and edge heating occurs in which only the edge portion is strongly heated.

On the other hand, if the coil in the metal substrate heating apparatus of the present invention is used, the integrated value of the induced current flowing at each point at the end and the center of the metal substrate being conveyed can be calculated. Can be made substantially equal in the width direction, and the temperature can be made uniform in the width direction.

Further, in the present invention, there is no need to provide a shielding plate between the coil and the metal base, so that the coil and the metal base can be brought close to each other. This makes it possible to further increase the number of lines of magnetic force passing through the metal base material and to perform induction heating on the metal base material more efficiently. in this way,
ADVANTAGE OF THE INVENTION According to this invention, a strip | belt-shaped metal base material can be efficiently heated uniformly in the width direction.

According to the fifth aspect of the present invention, the coil substantially excludes the total of the coil widths along the conveying direction of the metal material in the orbital portion except for the portions facing the both side edges of the metal base material. It has a uniform configuration. The heating temperature of the metal substrate is proportional to the integrated value of the induced current. Then, the integrated value of the induced current is proportional to the sum of the coil widths. Therefore, with such a configuration, more uniform heating can be performed in the width direction of the metal base material.

Further, according to the present invention, the magnetic material for adjusting the magnetic flux is arranged near the portion of the coil facing the both sides of the metal base. Thereby, the temperature distribution in the width direction of the metal base material can be further uniformed.

According to the seventh aspect of the present invention, the coil has a curved portion at a portion facing both side edges of the metal base,
The coil is configured such that at least a part of the outer peripheral edge of the curved portion projects outwardly from both side edges of the metal base by the same degree, and the inner peripheral edge of the curved portion is located inside the both side edges.

By arranging the coil in this way, the vicinity of the side edge of the metal base can be heated to the same temperature as other regions. As a result, heating can be performed at a uniform temperature over the entire region in the width direction. If all the outer peripheral edges of the curved portion are located inside the both side edges, the induction heating of the side edge portions becomes insufficient, and it becomes difficult to uniformly heat. On the other hand, even when the inner peripheral edge of the curved portion is located outside the both side edges, the distance over which the induced current flows in the transport direction along the side edge of the base material increases, and edge heating occurs. As a result, the side edge portions are excessively heated, and it is difficult to uniformly heat them.

According to the eighth aspect of the present invention, there is provided a structure having a rotating means for rotating the coil in a circumferential plane. In this way, if the coil rotating means is provided, the length of the coil extending in the width direction of the metal base can be easily changed. Therefore, the heating state in the width direction of the metal base is adjusted so that the metal base is uniformly heated in accordance with the width of the metal base, and an optimum temperature distribution can be easily realized. The side edge of the base material is most easily heated when the major axis of the coil coincides with the width direction of the metal base material, and is less likely to be heated as the inclination angle of the major axis with respect to the width direction increases.

Further, even when the width of the metal substrate is changed, if the inclination angle of the long axis of the coil is adjusted by rotating the coil, the optimum edge heating state can be obtained for the metal substrates having different widths. Can be easily set.

Further, according to the present invention, even if the width of the metal substrate is changed, it is basically unnecessary to replace the induction heating coil. Further, it is not necessary to partially shield the lines of magnetic force generated by the induction heating coil with the shielding plate to limit the heating range. Thereby, even if the width of the metal base material changes, it is possible to efficiently and uniformly heat the width of the metal base material with a simple configuration.

Further, according to the ninth aspect of the present invention, there is provided a structure having moving means for moving the coil in parallel in the width direction of the metal base. In this way, if the means for moving the coil in the width direction is provided, the position of the heating range in the width direction can be easily adjusted. For example, the center axis of the coil and the center line in the width direction of the metal base can be easily matched. As a result, the metal substrate can be heated symmetrically with respect to the center line in the width direction. For this reason, the metal substrate can be more uniformly heated.

Further, according to the tenth aspect of the present invention, the planar shape of the winding surface of the coil is a rhombus in which at least the corners facing the both side edges of the metal base among the four corners are curved. If the coil is formed in such a shape, the four sides of the rhombus are linear, so that the sum of the coil widths along the transport direction of the metal substrate can be easily made constant. In addition, even when the coil is rotated, the total of the coil widths can be uniformly maintained.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. First, referring to FIG.
The shape and arrangement of the induction heating coil constituting the heating device of the present embodiment will be described. The coil 2 for induction heating is arranged such that the orbital surface of the coil 2 faces the metal substrate surface,
Induction heating is performed while the belt-shaped metal substrate 1 is transported in the longitudinal direction.

The coil 2 orbits in the same plane.
It has a rhombic planar shape in which at least corners on the long axis 3 among the four corners are curved. That is, the curved portion 20 is provided at both end portions of the long axis 3 in the orbiting portion. If the coil is wound a plurality of times in the same plane, the current circulates by the number of turns, so that the generated magnetic field becomes strong and the number of lines of magnetic force passing through the metal base increases. In other words, the number of magnetic lines that do not pass through the metal base material is reduced, so that the induced current is increased and the heating efficiency is improved.

Further, since the coil 2 is schematically shown in FIG. 1, the corners on the short axis of the coil 2 are not rounded. However, the actual shape is, for example, a rhombus with four rounded corners as shown in FIG. The planar shape may be as follows. FIG. 2A shows a case where the coil is made three times, and FIG. 2B shows a case where the coil is made five times. The heating efficiency tends to increase as the number of turns of the coil in the same plane increases. However, when the number of rounds exceeds a certain number (for example, five rounds), the heating efficiency tends to be saturated.

Here, the reason why the shape of the coil 2 is such a rhombus will be described with reference to FIG. 3 (A) to 3 (C) schematically show the planar shapes of the coil in the orbiting plane. First, as in the case of the coil 2a shown in FIG. 3A, when the opposing orbiting portions of the coil 2a are close to each other like a hairpin, the heating efficiency is low because there are few lines of magnetic force passing through the metal base material. In addition, since edge heating occurs, it is difficult to heat the metal substrate in the width direction to a uniform temperature.

On the other hand, when the opposing orbiting portions of the coil 2b are separated to some extent (Lb> La) as in the coil 2b shown in FIG. Heating efficiency is improved. However, also in this case, the vicinity of the side edge of the metal base material is also heated to the same extent as the other regions, so that edge heating occurs and it is difficult to heat the metal base material to a uniform temperature.

Therefore, in the present embodiment, as shown in FIG. 3C, the shape of the coil 2 is the widest at the center in the width direction of the metal substrate in the transport direction of the metal substrate. . That is, the distance along the transport direction of the metal substrate between the orbiting portions facing each other with the long axis of the coil 2 therebetween is longer near the center of the longer axis 3 and becomes shorter as it approaches both ends of the longer axis. So that the coil goes around. That is, in the coil 2, the distance L1 near the center is longer than the distance L2 near the edge. Here, the long axis of the coil 2 refers to the axis in the direction in which the diameter of the coil 2 is the longest.

By forming the coil 2 in such a shape, the circulating shape of the induced current circulating in the same or the same shape as the coil 2 in the metal base material facing the coil 2 is changed in the width direction of the metal base material. It is the largest in the transport direction at the center. Thereby, the heating temperature in the width direction of the metal substrate can be made uniform.

Further, since the coil 2 of the present embodiment has a rhombic shape in particular, the total of the coil widths along the transport direction of the metal material in the orbital portion excluding the portions facing the both side edges of the metal base material is as follows. Substantially uniform. That is,
Except for the vicinity of both ends of the long axis of the coil, the total of the coil widths of the winding portions on the same straight line parallel to the transport direction of the metal material is substantially uniform. That is, as shown in FIG. 1, the widths d1 and d along the straight line of the circling portion crossed by the same straight line of the circling portion corresponding to the four sides of the rhombus.
The value of the sum (d1 + d2), which is the sum of 2, is a constant value regardless of the position of this straight line.

Here, the graph of FIG. 4 shows the relationship between the total coil width along the transport direction and the heating temperature. The horizontal axis of the graph represents the total (mm) of the coil widths, and the vertical axis represents the temperature of the substrate (° C.) subjected to the induction heating. The white circles (○) in the graph indicate the measured values of the temperature corresponding to the portion between the inner peripheral edges of the coil, and the straight line I is obtained from these measured values. Also, the black square mark (◆) in the graph
Shows the measured values of the temperature of the base portion corresponding to the portion between the inner peripheral edge and the outer peripheral edge of the curved portion, and the straight line II is obtained from these measured values.

From the straight lines I and II, it can be seen that the heating temperature of the metal substrate increases linearly as the sum of the coil widths increases. Therefore, the sum of the coil widths (d1 + d
By making 2) uniform, more uniform heating in the width direction of the metal substrate 1 can be performed. The reason why the heating temperature depends on the sum of the coil widths as described above is that, when focusing on a certain point in the metal substrate, the amount of temperature rise due to heating is proportional to the integral value of the induced current flowing through that point during conveyance. To do that. The induced current flowing through the metal substrate is considered to be similar or identical to the shape of the coil facing the metal substrate except for the curved portion of the coil. Therefore, if the sum of the coil widths along the coil conveying direction is made uniform, the heating temperature of the metal base material becomes uniform. The relationship between the coil widths d1 and d2 may be d1ｄd2 or d1 = d2, and the sum thereof may be uniform. However, it is preferable that d1 = d2 in terms of cost.

Further, in the present embodiment, as shown in FIG. 1, the coil 2 has curved portions 20 at both ends of the long axis 3 of the orbiting portion. Then, the coil 2 is connected to the bending portion 2
0 at least a portion of the outer peripheral edge 21 of the metal base member 1 projects outwardly from both side edges 10 by the same degree, and the curved portion 2
The inner peripheral edge 22 is located inside the side edges 10.

When the curvature of the curved portion is small, the induced current generated in the base material cannot be bent along the curved portion, and tends to pass inside the coil curved portion. In this case, the outer peripheral edge side of the curved portion of the coil is not easily heated. When the curvature of the curved portion is large, the induced current pattern generated on the base material becomes close to the shape of the coil. However, this is the case where the influence of the base material side edge is removed. Therefore, in addition to the induction current circulating path formed by the coil shape whose central portion is separated along the transport direction and the sum of the coil widths, the third point for equalizing the temperature distribution in the width direction of the substrate heating is the inner peripheral edge. Is the curvature.

If the diameter of the coil 2 in the direction of the major axis 3 is too short, the outer peripheral edge 21 of the curved portion 20 is all located inside the both side edges 10. In that case, the induction heating near the side edge 10 becomes insufficient, and it becomes difficult to uniformly heat the metal substrate 1 in the width direction. On the other hand, if the diameter of the coil 2 in the major axis 3 direction is too long, the inner peripheral edge 22 of the curved portion 20 is also located outside the both side edges 10. In this case, edge heating occurs, and the vicinity of the side edge 10 is excessively heated, and it becomes difficult to uniformly heat the metal base material 1.

In the present embodiment, the heating state of the side edges is adjusted by rotating the coil 2 in the orbital plane and changing the angle of inclination of the long axis 3 with respect to the width direction of the metal substrate 1.

As described above, by rotating the coil, the length of the coil can be easily changed. Thereby, the amount of protrusion of the curved portion 20 of the coil 2 from the side edge 10 can be changed, and the heating state of the side edge portion can be adjusted according to the width of the metal base material. The side edge portion is most easily heated when the major axis coincides with the width direction of the metal base material, and becomes less likely to be heated as the inclination angle of the major axis with respect to the width direction increases.

Here, the relationship between the angle of inclination of the coil and the temperature distribution in the width direction of the metal substrate will be described with reference to FIG. In measuring the temperature distribution shown in FIG. 5, a strip-shaped aluminum substrate having a width of 225 mm and a thickness of 0.28 mm as the metal substrate 1 was induction-heated while being conveyed at a constant speed of 6.5 m / min. As a coil 2, a copper pipe was wound five times as shown in FIG.
A coil having a minor axis diameter of 125 mm was used, and this coil was arranged at a distance of 10 mm from the metal substrate 1 being transported. As the heating conditions, a voltage of 100 V and a current of 6
DC of 1 A was converted into a high frequency of 25 kHz and applied. As a result, at a power consumption of 6.1 kW, the metal substrate 1 could be induction-heated from room temperature 26 ° C. to an average temperature of 210 ° C. or more with a heating efficiency of 50% or more. The higher the resistivity of the metal substrate to be heated, the higher the heating efficiency.

5A to 5C, the horizontal axis represents the position (mm) in the width direction of the metal substrate 1, and the vertical axis represents the substrate temperature (° C.). Curve III in FIG.
Means that the major axis 3 of the coil 2 is
9 shows a temperature distribution when tilted by 9 °. A curve IV in FIG. 5B shows a temperature distribution in the case where the temperature is inclined by 23 °. Further, a curve V in FIG. 5C shows a temperature distribution when tilted by 35 °.

When the inclination angle shown in FIG. 5A is 19 °, edge heating has occurred. As a result, curve II
As shown by I, the temperature near the center of the metal substrate is relatively low, and the temperature near the side edges is relatively high, and the temperature distribution is non-uniform.

On the other hand, when the inclination angle shown in FIG.
In the case of °, the heating near the side edge 10 of the metal substrate 1 is insufficient. As a result, as shown by the curve V, the temperature near the center of the metal base material is relatively high, and the temperature near the side edges is relatively low, and the temperature distribution is non-uniform. In particular, the temperature drops significantly near the right end of the graph.

On the other hand, when the inclination angle is 23 ° shown in FIG. 5B, the heating range of the coil 2 matches the width of the metal base 1. Thus, as shown by curve IV,
The metal substrate 1 is heated with a substantially uniform temperature distribution over the entire width direction. In detail, in this case, from the side edge to the center of the base material, the temperature pattern once rises and then becomes a constant value. In this case, the inner peripheral curvature of the curvature is small, and the curvature becomes more uniform by slightly increasing the curvature. The coil used for induction heating shown in FIG. 5 has a radius of curvature of 10 mm, but when the radius of curvature is 12 mm, the curve in the graph of FIG.
As shown in VI, the temperature distribution became more uniform. The radius of curvature is preferably in the range of 11.5 to 12.5 mm.

The curve VII in the graph of FIG.
In the case of the temperature distribution in the width direction of the metal base material, 25 mm and 195 m near the end of the coil in the width direction are shown.
The temperatures near m and around 105 mm near the center of the coil are relatively lower than the temperatures of the other parts. Therefore, a ferrite core, which is a magnetic material for adjusting magnetic flux, is arranged in the vicinity of the coil at a position corresponding to a portion where the temperature is low in the width direction. As a result, as shown by a curve VIII in the graph of FIG. 7B, the magnetic flux distribution changed, and the temperature distribution became more uniform.

The width of the metal substrate to be heated is not limited to a fixed value but may be changed. Even in such a case, if the inclination angle of the long axis 3 of the coil 2 is adjusted, the optimal heating range can be easily set for each of the metal bases having different widths.

Here, the adjustment of the heating range when the width of the metal base 1 is changed from W1 to W2 will be described with reference to FIG. In FIG. 8, the coil 2 arranged in accordance with the width W1 indicated by the side edges 10 of the metal base is indicated by a solid line. The long axis 3 of the solid coil 2 is substantially parallel to the width direction of the metal substrate.

On the other hand, the imaginary line shows the coil 2i arranged in accordance with the width W2 indicated by the side edges 10a of the metal base. The major axis 3i of the imaginary line coil 2i is inclined by an angle θ with respect to the major axis 3 of the solid coil 2. Due to the inclination, the heating range of the imaginary line by the coil 2i is narrowed in accordance with the width W2. If the metal substrate having the width W2 is heated without inclining the solid-line coil 2, edge heating occurs and it becomes difficult to heat uniformly.

Next, with reference to FIG. 9, an example of the arrangement of coils for inductively heating the aluminum base material and an example of a device configuration in the step of laminating resin films on both surfaces of the aluminum base material 1 will be described. FIG. 9A is a plan view of the device, and FIG. 9B is a cross-sectional view taken along line AA of FIG. 9A.

In the example shown in FIG. 9, two coils 2 are arranged on both sides of the aluminum substrate 1 along the transport path of the aluminum substrate 1 to be heated. In addition, each coil 2
Are fixed to the fixed base 4. The fixed base 4 includes a ferrite core and functions as a magnetic field shielding plate. For this reason, by providing this fixed base 4, the coupling of the magnetic field to the metal substrate can be strengthened. In FIG. 9A, illustration of the fixed base 4 is omitted.

Then, from both sides, two coils 2
The aluminum base material 1 that has been induction-heated is transported downward in the drawing. Subsequently, this aluminum base material 1
Is sandwiched between resin films 8 extruded. Then, the aluminum substrate 1 and the resin film 8 are pressed by the laminating roll 7.

FIG. 10 shows an apparatus for arranging the coil 2 shown in FIG. As shown in FIG. 10, by turning the handle 11, the fixed base 4 can be rotated through the chain 12 within a range of, for example, ± 40 °. As a result, as described above, the heating of the edge can be easily set to be optimal according to the width of the aluminum substrate 1.

Further, the fixed base 4 can move the rotation center 15 of the fixed base 4 in parallel in the width direction of the aluminum base material via the support member 16 by moving the lever 14 right and left. By this parallel movement, the position of the heating range in the width direction is adjusted. For example, the center axis of the coil 2 and the center line of the aluminum substrate 1 in the width direction are easily matched,
The aluminum substrate 1 can be heated symmetrically. In addition, for example, the curved portion 20 of the coil 2 can be easily extended to the outside of both side edges 10 of the aluminum base material 1 by the same degree and can be disposed. Thereby, the aluminum substrate 1 can be more uniformly heated in the width direction.

In the above-described embodiment, an example has been described in which the present invention is configured under specific conditions. However, the present invention can be variously modified. For example, in the above-described embodiment, an example has been described in which the planar shape of the coil is a rhombus shape with rounded four corners, but in the present invention, the planar shape of the coil is not limited to this. For example,
The planar shape of the coil may be an elliptical shape or a parallelogram shape with rounded corners.

In the above-described embodiment, an example has been described in which induction heating is performed using a coil that is turned only in the same plane. However, in the present invention, the shape of the coil is not limited to this. For example, induction heating may be performed by using two-tiered coils shown in FIG. 2A or 2B.

In the above embodiment, the planar shape of the coil is a line-symmetric shape with respect to the long axis. However, in the present invention, the planar shape of the coil is not limited to this. For example,
The shape may be asymmetric with respect to the long axis.

Further, in the above-described embodiment, an example in which the coil is rotated about its central axis has been described. However, in the present invention, if the coil is translated in the width direction of the metal base material, The coil may be rotated about a point other than its center axis.

Further, in the above-described embodiment, an example has been described in which the metal base material is heated only by induction heating, but in the present invention, induction heating and another heating method may be combined.

[0062]

As described above, according to the present invention, the occurrence of edge heating can be suppressed, and the heating temperature in the width direction can be made uniform. Further, if the coil is made rotatable, the length of the coil extending in the width direction of the metal base can be easily changed. For this reason, the amount of protrusion of the curved portion can be easily adjusted according to the width of the metal base material. As a result, even when the width of the metal substrate is changed, uniform heating can be realized with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining the shape and arrangement of a coil for induction heating.

FIGS. 2A and 2B are plan views illustrating the shape of a coil according to the embodiment.

FIGS. 3A to 3C are explanatory diagrams of coil shape conditions.

FIG. 4 is a graph showing the relationship between the total coil width along the transport direction of a metal substrate and the temperature of the substrate.

FIGS. 5A to 5C are graphs showing the relationship between the arrangement of coils and the temperature distribution.

FIG. 6 is a graph showing a temperature distribution when a radius of curvature of a coil end is changed.

FIGS. 7A and 7B are graphs for explaining correction of a temperature distribution by a ferrite core.

FIG. 8 is a diagram showing a state in which a coil is rotated when the width of a metal base is changed.

FIG. 9A is a diagram showing an arrangement of coils in the embodiment, and FIG. 9B is a cross-sectional view of FIG.

FIG. 10 is a side view for explaining the structure of a heating device for a metal substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal substrate 2, 2a, 2b Coil 3 Long axis 4 Fixed base 5 Extrusion die 6 Support roll 7 Laminating roll 8 Resin film 10, 10a Side edge 11 Handle 12 Chain 13 Pulley 14 Lever 15 Fixed center rotation center 16 Connection member 20 Bending part 21 Outer edge 22 Inner edge

Claims (10)

[Claims] 1. A method for inductively heating a conveyed strip-shaped metal substrate with a coil wound so as to face the metal substrate, wherein a circular shape of an induced current circulating in a similar or identical shape to the coil. In the direction of conveyance in the center in the width direction of the metal base material. 2. The heating of a metal substrate according to claim 1, wherein the integrated value of the induced current circulating in the metal substrate during transportation is made substantially uniform in the width direction of the metal substrate. Method. 3. The metal base according to claim 1, wherein the magnetic field lines generated by the coil and passing through the metal base are partially concentrated or expanded to concentrate or expand the induced current. Heating method. 4. A heating device for induction heating while conveying a strip-shaped metal base material in a longitudinal direction, wherein the coil for induction heating is arranged such that a circumferential surface of the coil faces the metal base material surface. The heating device for a metal base, wherein the shape of the coil is the largest at the center in the width direction of the metal base in the transport direction of the metal base. 5. The coil according to claim 1, wherein a total of coil widths along a conveying direction of the metal material is substantially uniform in a circling portion excluding portions facing both side edges of the metal base material. The heating device for a metal substrate according to claim 4, wherein 6. A heating apparatus for a metal base according to claim 4, wherein a magnetic body for adjusting a magnetic flux is arranged in the vicinity of portions of the coil facing both side edges of the metal base. 7. The coil has a curved portion at a portion facing both side edges of the metal base, and the coil has at least a portion of an outer peripheral edge of the curved portion outside the both side edges of the metal base. 7. The metal substrate heating device according to claim 4, wherein the projections are arranged so as to be approximately equal to each other, and the inner peripheral edge of the curved portion is located inside the both side edges. 8. The apparatus for heating a metal base according to claim 4, further comprising a rotating unit configured to rotate the coil in the orbital plane. 9. The apparatus for heating a metal base according to claim 4, further comprising moving means for moving the coil in parallel in a width direction of the metal base. 10. The coil according to claim 4, wherein a planar shape of the winding surface of the coil is a rhombus in which at least four corners facing corners of the metal base are curved. A heating device for a metal substrate according to any one of the above.