JP3336964B2 - Induction heating device for metal plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating apparatus for inductively heating a metal sheet such as a hot-rolled steel sheet being conveyed, and more particularly to suppressing sparks generated between the metal sheet and a conveying roll.

[0002]

2. Description of the Related Art For example, high-pressure water is sprayed on the surface of a hot-rolled steel sheet after rough rolling for descaling, but at this time, the side ends of the steel sheet are supercooled as compared with the central part. Further, in the case of a thick steel plate, the side end of the steel plate is similarly supercooled by water cooling or accelerated cooling during controlled rolling.

[0003] In order to overcool the side end of such a steel plate, a method of induction heating the side end of the metal plate being conveyed by an induction coil has been adopted. However, since a metal transport roll is used for transporting the metal plate, an induced electromotive current is generated in the metal plate with the induction heating of the side end by the induction heating coil. A part of the induced electromotive current flows as a ground current via a transport roll (ground roll). Therefore, when the metal plate and the transport roll separate,
Sparks occur between the metal plate and the transport roll. When this spark is generated, a spark mark is generated on the metal plate, and the product value is significantly reduced. As a technique for suppressing the generation of the spark, for example, Japanese Unexamined Patent Application Publication No.
There is an induction heating device disclosed in Japanese Patent No. 38712.

FIG. 4 is a diagram showing a configuration of an induction heating apparatus disclosed in Japanese Patent Application Laid-Open No. 9-38712. In this induction heating device, the metal plate 3 is transported by the transport rolls 2a, 2a.
b, and is provided with two induction heating coils 4 for heating the metal plate side end. At the side end of the metal plate 3 between the induction heating coil 4 and the transport rolls 2a or 2b, side rolls 1a and 1b grounded by a lead wire 12 are installed.

In the induction heating apparatus shown in FIG. 4, the side ends of the metal plate between the induction heating coil 4 and the transporting roll are brought into contact with the grounded side rolls 1a and 1b, whereby
The current that is about to flow from the metal plate 3 to the transport rolls 2a and 2b flows through the grounded side rolls 1a and 1b, and the induced electromotive current causes the transport rolls 2a and 2b of the metal plate 3 to move.
b to prevent it from spreading to the area above
The earth current flowing through a and 2b is reduced.

[0006]

FIG. 5 is a characteristic diagram showing an example of the spread of the induced electromotive current with respect to the position of the induction coil in FIG. As is clear from the characteristics of FIG. 5, when the metal plate is induction-heated by the induction heating coil, the distribution of the induced electromotive current is highest near the induction coil and becomes smaller as the distance from the induction coil increases.

In the induction heating apparatus shown in FIG. 4, as described above, a side roll (earth roller) is provided between the induction heating coil and the nearest transport roller, and the induced electromotive current is grounded from the side roll. For this reason, grounding occurs in a region where the induced electromotive current is maximum, and there is a high possibility that sparks will occur on the end face of the metal plate. Further, since the current flowing through the side rolls is large, the durability of components that contribute to flowing the current in the apparatus is poor. Moreover, it is difficult to arrange a side roll near the induction heating coil due to the actual configuration. Further, a decrease in the heating efficiency is also conceivable.

[0008] The present invention has been made to solve the above-mentioned problems, and has as its object to provide an induction heating apparatus capable of suppressing generation of sparks.

[0009]

An induction heating apparatus according to the present invention is an apparatus for inductively heating a metal plate by an induction heating coil while placing and transporting the metal plate on a transport roller.
A plurality of insulated and conveyed rollers arranged in the vicinity of the induction heating coil and insulated and supported; and Grounding devices with vertical rolls in contact with the ends and electrically grounded.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 (A) and 1 (B) are a plan view and a front view showing a configuration of an induction heating device according to Embodiment 1 of the present invention. Induction coil 11 is metal plate 1
The two sides of the metal plate 10 are arranged so as to be induction-heated from both sides. Grounding devices 12a and 12b are provided at positions separated from the induction coil 11 by a predetermined distance in the entrance direction and the exit side, respectively. The earthing devices 12a and 12b include a vertical roll 13 and a cylinder 14
, Respectively. The vertical roll 13 is a metal plate 1
The metal plate 10 is arranged so as to face the metal plate 10, and the position thereof is adjusted by the cylinder 14 in a direction orthogonal to the transport direction of the metal plate 10 and pressed against the end face of the metal plate 10. Further, the vertical roll 13 is grounded and is always at the ground potential.

The metal plate 10 is transported by the transport rollers. Of the transport rollers, the transport rollers 15a disposed between the grounding devices 12a and 12b are all insulated below the bearings. Further, the transport roller 12b on the input side of the grounding device 12a and the transporting roller 12c on the output side of the grounding device 12b are not insulated, and are grounded by their mechanisms.

In the induction heating device configured as described above, the metal plate 10 is transported by the transport rollers 15b, 15a, 15c.
While being transported above, the side end portion is
And induction heating. In the case of the induction heating, the metal plate 1
The induced electromotive current flows through the transport roll 15 at that time.
Next, the operation for the a, 15b, 15c and the vertical roll 13 will be described.

(A) Transport Roller 15a When the lower surface of the metal plate 10 is in contact with the transport roll 15a, part of the induced electromotive current of the metal plate 10 flows to the transport roll 15a. Therefore, when the lower surface of the metal plate 10 is separated from the transport roll 15a (when the metal plate rises), a spark may be generated.
The induced electromotive current flowing through the transport roll 15a is small, and there is almost no possibility of spark generation.

(B) Grounding devices 12a, 12b The vertical rolls 13 of the grounding devices 12a, 12b are grounded. For this reason, the induced electromotive force of the metal plate 10
When the end of the metal plate 10 is separated from the vertical roll 13, a spark may be generated, but the vertical roll 13 is sufficiently separated from the induction heating coil 11. As can be seen from the characteristic diagram of FIG. 5, since the induced electromotive current is sufficiently small, there is practically no possibility of spark generation. Even if a spark is generated, the current is small and the spark mark is also small.

(C) Transport Rolls 15b, 15c These transport rolls 15b, 15c are also grounded. For this reason, the induced electromotive current of the metal plate 10 flows from the lower surface of the metal plate 10 to the transport rolls 15b and 15c, respectively. When the lower surface of the metal plate 10 is separated from the transport rolls 15b and 15c, a spark is generated. Although there is a possibility, since a part of the induced electromotive current flows into the vertical roll 13,
The current flowing through the transport rolls 15b and 15c is extremely small. Therefore, there is practically no possibility that a spark will occur. Even if a spark is generated, the current is small and the spark mark is also small.

In the embodiment of FIG. 1, as described above, the occurrence of spark marks can be suppressed or reduced, but the following effects are also obtained. In the present embodiment, the equipment arrangement is easy. That is, as in the related art (FIG. 4), the space between the nearest conveying rollers provided with the induction heating coil is limited by the provision of the induction heating coil. In addition, since the grounding device includes a moving mechanism (cylinder) for moving the vertical roll in a direction orthogonal to the transport direction,
This also makes it difficult to arrange the equipment. However, in the present embodiment, the grounding devices 12a, 12b
Is provided at a position away from the induction heating coil 11, thereby facilitating the arrangement of the equipment.

In this embodiment, the heating efficiency is not hindered. That is, when a grounding device is provided near the induction heating coil as in the related art (FIG. 4), a large induction electromotive current flows through the side roll, and the heating efficiency of the metal plate is reduced. However, in this embodiment, since the grounding devices 12a and 12b are provided at positions away from the induction heating coil 11, such adverse effects can be avoided.

Embodiment 2 FIG. FIG. 2 is a front view showing the configuration of the induction heating device according to Embodiment 2 of the present invention. In this embodiment, the grounding device is provided only on the outlet side.
This is because a line configuration that allows a long installation range of the insulating roller is adopted as the entrance-side conveyance roller, and the entrance-side grounded conveyance roller has a sufficient insulation distance from the induction heating coil 11. Therefore, the induced electromotive current is sufficiently small until the spark does not occur, and the problem of spark generation does not occur. Also, the grounding device 12
The transport roller on the output side of b may be insulated.
By doing so, the drive control of the grounding device 12b becomes easy.

Embodiment 3 FIG. In the case of the above-described embodiment, the grounding device is provided only on the output side. On the contrary, a line configuration that allows a long installation range of the insulating roller is adopted as the transport roller on the output side. In this case, a grounding device may be provided only on the entrance side. In the grounding devices of the first and second embodiments, one vertical roll is provided for one grounding device.
It is also possible to equip the table with two vertical rolls and swing the mounting seat to improve the followability.

[0020]

FIG. 3 is a front view showing the configuration of an induction heating apparatus according to an embodiment of the present invention. In the present embodiment, two induction heating coils are provided, and grounding devices are arranged on the entrance side and the exit side of the induction heating coil, respectively, and the transport rollers therebetween are all insulated and supported. Further, the pitch between the rollers is 800 to 1000 mm. In this embodiment, two insulating rollers are arranged on the inlet side of the induction heating device and eight insulating rollers are arranged on the outlet side. The size of the vertical roller of the grounding device is φ130
× 150 (length).

A description will be given of the state of occurrence of sparks when the present embodiment is used and when no spark countermeasures are taken. The material to be heated is a carbon steel strip having a thickness of 30 mm, a width of 1200 mm, and a length of 50 m, and the power supplied to the induction heating device (two units) is 100.
0 KW. If no measures were taken under these conditions, countless spark marks with a diameter of about 2 mm were generated on the product surface. However, no spark marks were generated in this example.

[0022]

As described above, according to the present invention, a plurality of insulated conveying rollers are arranged in the vicinity of the induction heating coil, and the insulated conveying roller located closest to the entrance and / or the exit side with respect to the induction heating coil. By installing a grounding device near the
The induced electromotive current flowing through the grounding device and the transport roller that is not insulated and supported is small, and therefore, the occurrence of spark is suppressed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an induction heating device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an induction heating device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of an induction heating device according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional induction heating device.

FIG. 5 is a characteristic diagram showing a distribution of an induced voltage by an induction heating coil.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI H05B 6/10 381 H05B 6/10 381 (56) References JP-A-9-38712 (JP, A) JP-A-5-33040 (JP, A) JP-A 4-134203 (JP, U) JP-A 3-126208 (JP, U) (58) Fields studied (Int. Cl. ⁷ , DB name) B21B 45/00 C21D 1 / 42 C21D 9/60 101 H01R 4/64

Claims (2)

(57) [Claims] An apparatus for inductively heating a metal plate with an induction heating coil while placing and transporting the metal plate on a transport roller, wherein a plurality of insulated transport rollers disposed near the induction heating coil and insulated and supported. An earth provided with vertical rolls which are provided in the vicinity of the insulated conveyance roller positioned on the most entrance side or the exit side with respect to the induction heating coil, respectively contact the side ends of the metal plate and are electrically grounded. An induction heating apparatus for a metal plate, comprising: an apparatus; 2. An apparatus for inductively heating a side of a metal plate with an induction heating coil while placing and transporting the metal plate on a transport roller, comprising: a plurality of insulating and support members arranged near the induction heating coil and insulated and supported; A transport roller, and an entrance side provided with a vertical roll that is provided near the insulating transport roller positioned closest to the induction heating coil and that is in contact with a side end of the metal plate and that is electrically grounded. A grounding device, and a delivery side provided with a vertical roll that is provided near the insulating conveyance roller positioned closest to the delivery side with respect to the induction heating coil and is in contact with a side end of the metal plate and electrically grounded, respectively. An induction heating device for a metal plate, comprising: a grounding device.