JPH09103804A - Induction heating device for band plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating device heating uniformly and joining slabs regardless of a difference in the width dimensions of the slabs by equipping at least two pairs of inductors along the width direction of a band plate on the induction heating device, and arranging a plate which is a magnetic substance between the inductors. SOLUTION: A plate P made of a magnetic substance is arranged in a gap L formed between adjacent inductors 1a. Consequently, since the plate P becomes a magnetic path, an alternating field applied by the inductors 1a penetrates slabs S1 and S2 in the same way in the gap. Therefore, a temperature increase almost equal to those in the other areas can be expected, and continuous hot rolling with high productivity can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to heating a plated steel sheet or the like uniformly in the width direction during its transportation, or heating a strip plate such as a sheet bar at its leading and trailing ends one after another.
The present invention relates to an induction heating device which is particularly useful for joining and continuously hot finishing rolling it.For example, in the following, a steel bar such as a sheet bar is heat joined and continuously hot finished rolling is taken as an example. Explain.

[0002]

2. Description of the Related Art Conventionally, in a hot rolling line, a strip to be rolled (hereinafter referred to as a "steel piece") is heated at its end, and then subjected to rough rolling and finish rolling one by one to obtain a desired thickness. However, in such a batch-type rolling method, troubles such as line stop are likely to occur due to defective biting of the rolled material in finish rolling. However, there is an unavoidable disadvantage that the yield is reduced due to the defective shape at the front and rear ends of the.

Japanese Patent Laid-Open No. 5-185109 and Japanese Patent Laid-Open No. 6-155047 disclose attempts to solve the above problems in hot rolling of steel slabs and further improve productivity. There are known rolling techniques.

In any of the techniques disclosed in the above publications, the rear end of the steel piece that is conveyed first and the front end of the steel piece that is conveyed subsequently on the entry side of the finish rolling step are heated (induction heating) one after another. ) Are joined and continuously supplied to a rolling facility for hot finish rolling. According to this method, the biting failure that occurs in the conventional method of rolling steel pieces one by one is performed. It will not happen and productivity can be significantly improved.

By the way, in such a method, it is necessary to securely join the preceding steel piece and the following steel piece in a short time. However, in rolling for a steel piece having a particularly large width dimension,
Since it is difficult to uniformly heat the entire area to be joined, a joining failure portion occurs, and there is a disadvantage that the plate is broken from this portion during hot finish rolling and a stable rolling operation cannot be performed.

In order to realize uniform heating of the steel slab, it is effective to increase the size of the inductor for induction heating according to the width of the steel slab, but the target is a steel slab having a width of more than 1 m. However, it is difficult at present to prepare an inductor corresponding to this (manufacturing is difficult because of the insulating structure because the applied voltage per turn increases due to the increase in inductance per turn). There was a situation.

In this regard, a technique as disclosed in Japanese Patent Application No. 5-293298, in which a plurality of inductors are provided in the widthwise direction of the steel slab to realize heating corresponding to the change in width dimension of the steel slab. However, in a heating device with multiple inductors, a coil, an insulator, a protective frame, etc. are placed around the iron core that constitutes the inductor, so there is a mechanically constant gap between the inductors. It is unavoidable that the steel sheet is formed, and there is a disadvantage that the region of the steel slab located immediately below the gap is inevitably insufficient in temperature rise as compared with other regions.

Incidentally, Japanese Patent Application No. 5-316751 discloses a means for reducing the above gap to reduce the region of insufficient temperature rise, but this means is still sufficient. Absent.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to propose a novel induction heating device capable of uniformly heating and joining regardless of the difference in width dimension of steel slabs.

[0010]

According to the present invention, there is provided an inductor having magnetic poles sandwiched in a thickness direction of a strip plate, and an alternating magnetic field is applied by the inductor to induce an alternating current in the strip plate for induction. A heating device, wherein the induction heating device is provided with at least two sets of inductors along the width direction of the strip plate, and plates of magnetic material are arranged between the inductors. An induction heating device, in which the plate has moving means that can be moved toward and away from the strip, is particularly suitable.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings. As shown in Fig. 1, hot finish rolling equipment m
At the entry side of the front end of the leading steel strip S _{1 and} the leading end of the trailing steel strip S ₂ are made to face each other with a gap.
a, a power supply line 1b, and a power supply 1c having a structure as shown in FIG. 2 (a running type or a fixed type that moves in synchronization with the transportation of the billet is used as the heating device) When an alternating magnetic field is applied, steel strips S ₁ and S ₂ induce a current e having a distribution as shown in FIG. 3 (alternating current of medium frequency and high frequency of about 500 to 2000 Hz) e.

Then, particularly on the facing surface a, which is the planned joining surface of the steel slab, the electric current is particularly concentrated and flows in the region of the penetration depth δ due to the skin effect (the current density is high). Although it is preferentially heated by Joule heat generation as shown in FIG. 4, under the heating experiment using a heating device in which two sets of inductors 1a are arranged along the width direction of the steel slab, a gap L is formed between the inductors. It has been confirmed that, when present, the magnetic flux density decreases in the region of the gap L as shown in FIG. 2 (it is estimated that the alternating magnetic field is canceled by the leakage magnetic flux).
As described above, the degree of temperature rise of the steel slab just below that was smaller than that in other regions.

According to the present invention, a plate p made of a magnetic material is arranged in the gap L formed between the inductors 1a adjacent to each other as shown in FIG. Induct because p becomes a magnetic path
The alternating magnetic field applied by 1a also penetrates the steel slab even in the gap, so that it is possible to expect a temperature rise comparable to other regions as shown in the figure.

FIG. 6 is a schematic diagram showing the arrangement of the inductor 1a, the plate p, and the steel pieces S ₁ and S ₂ of the heating apparatus shown in FIG. 5 for easy understanding.

Any magnetic material can be applied to the plate p, but in terms of magnetic permeability, simplicity, and price,
It is most effective to use silicon steel sheet.

A gap L formed between the inductors
Is considered to be about 100 to 300 mm even if it can be made the smallest, and based on this, the thickness t of the plate p is preferably about 30 to 60 mm, even if it is of the integral type. It may be a divided type in which a plurality of thin plates are stacked.

Further, the plate p is placed on a predetermined position of the heating device to avoid damage to the inductor due to contact with the steel plate.
It is also possible to have a function as a guide for guiding S ₁ and S ₂ , and in this case, it is preferable to use ordinary steel from the viewpoint of mechanical strength although it is slightly inferior in terms of uniform heating.

In FIG. 7, the gap L formed between the inductors 1a is 100 mm, and the thickness t is 50 mm.
When the mm integrated plate p is arranged (CASE1), the thickness t: 50 mm is also divided type (there are two divisions with a gap between them).
If there is a plate p of 20 mm) (CASE2), the distance between the plate p and the steel slab is 1 for CASE1.
0 mm and CASE2 are the heating rates in the width direction of the billet when heated to 10 mm and 50 mm. However, the heating rate at the position 200 mm from the center of the plate without the plate p is shown as a reference.

It is apparent from FIG. 7 above that the utility of the plate p made of a magnetic material between the inductors is increased because the temperature rise rate at the plate center is increased. Here, a moving means such as the hydraulic cylinder 2 shown in FIG. 6 is provided, and the plate p is moved from the steel piece to 10
The temperature of the steel slab can be accurately adjusted because the temperature rising rate immediately below the slab can be changed by separating the slabs within a range of about 50 mm. In addition, the guide and guide function of the billet can be adjusted.

[0020]

[Example] A width of 1200 mm, a thickness of 30 mm, a front end and a rear end of a sheet bar having a temperature of 1000 ° C. are applied with a heating device having two sets of inductors arranged in the width direction of the sheet bar. Applied voltage: 4000 V, Input power: Heated and bonded under the condition of 4000 kW, and investigated the temperature distribution in the width direction after bonding.

The size of the magnetic pole of the inductor of the heating device used was 800 mm in the width direction of the seat bar and 200 mm in the longitudinal direction, and the distance from the magnetic pole to the seat bar was 80 mm both in the vertical direction. In addition, the gap formed between the inductors is 100 mm, and a plate with a thickness of 20 mm (material: S25
C, size: height 300 mm × length 800 mm) are arranged in two pieces (spaced with the sheet bar is 10 mm).

As a result, when the sheet bar is heated and joined by using the device according to the present invention, the temperature distribution in the width direction of the sheet bar becomes substantially uniform, and the joining over the entire width direction is possible. It could be confirmed.

[0023]

As described above, according to the present invention,
Uniform heating of the entire width direction of the steel pieces enables the steel pieces to be firmly joined to each other, and continuous hot rolling with high productivity can be performed. Further, according to the present invention, when it is used for heating a plated steel sheet or the like, uniform heating in the width direction of the strip makes it possible to supply a product of stable quality.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state of heating and joining steel pieces.

FIG. 2 is a diagram showing a configuration of a main part and a magnetic flux density in a width direction when a steel slab is heated by a conventional apparatus.

FIG. 3 is a diagram showing an alternating current distribution.

FIG. 4 is a diagram showing a temperature distribution at an end portion of a steel slab.

FIG. 5 is a diagram showing a configuration of a main part of a device according to the present invention and a temperature distribution in a width direction of a steel slab.

FIG. 6 is a perspective view of a main part of the device according to the present invention.

FIG. 7 is a diagram showing a temperature rising rate in the width direction of a steel slab.

[Explanation of symbols]

1 Heating device 1a Inductor 1b Power supply line 1c Power supply 2 Cylinder m Finishing and rolling mill p Plate S ₁ Leading billet S ₂ Trailing billet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masafumi Nagata 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Inside the Chiba Steel Works, Kawasaki Steel (72) Inventor Hideyuki Nikaido Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Kawasaki Steel Works Co., Ltd. Chiba Steel Works (72) Inventor Takeshi Hirabayashi 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Works Chiba Works (72) Inventor Toshiaki Amagasa Kawasaki-cho, Chuo-ku, Chiba City Kawasaki Steel Works Co., Ltd. Chiba Steel Works (72) Inventor Takahiro Yamazaki 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Works Chiba Works (72) Inventor Kazuo Morimoto 4-6 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture 22 Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory (72) Inventor Kazuya Tsurusaki 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Hishi Heavy Industry Co., Ltd. Hiroshima Research Institute (72) Inventor Toshinori Eguchi, 8-1-1 Tsukaguchi Honcho, Amagasaki City, Hyogo Prefecture Sanryo Electric Co., Ltd. Itami Works (72) Inventor Hiroyuki Nakano 8-1, Tsukaguchi Honcho, Amagasaki City, Hyogo Prefecture No. 1 Sanbishi Electric Co., Ltd. Itami Works

Claims (2)

[Claims] 1. An induction heating apparatus comprising an inductor having magnetic poles sandwiched in a thickness direction of a strip plate, wherein an alternating magnetic field is applied by the inductor to induce an alternating current in the strip plate for heating. An induction heating apparatus for a strip, wherein the apparatus includes at least two sets of inductors along the width direction of the strip, and plates of a magnetic material are arranged between the inductors. 2. The induction heating device for a strip plate according to claim 1, wherein the plate has a moving means capable of approaching and separating from the strip plate.