JPH04147596A - Induction heating of metallic thin plate - Google Patents

Abstract

PURPOSE:To uniformly heat a metallic thin plate to temperatures up to its magnetic transformation point by heating the metallic thin plate to its magnetic transformation point, then heating the plate using a solenoid coil so as to uniform the temperature distribution, and then heating the plate using transverse coils. CONSTITUTION:A metallic thin plate 2 is continuously fed by conveying rollers 9, 9 and heated from room temperature to its magnetic transformation point by transverse coils 8, 8 of the front stage. Temperature distribution at the A point is uneven at both ends as shown by the curve A, while temperature distribution at the B point located near the magnetic transformation point at which the plate passes through the transverse coil 8 of the second stage is uneven to a large extent as shown by the curve B. Thereafter, the plate 2 is subjected to induction heating by a solenoid coil 1 and then reaches its magnetic transformation temperature and when this temperature is maintained, temperature distribution at the C point at which the plate passes through the solenoid coil 1 is even as shown by the straight line C. When the plate 2 is heated to final temperature by the transverse coils 8, 8 of the rear stage temperature distribution at the outlet D point is almost even from end to end as shown by the curve D.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an induction heating method for uniformly heating a thin metal plate to a temperature equal to or higher than its magnetic transformation point.

(Prior Art) Conventionally, gas furnaces, heavy oil furnaces, and resistance electric furnaces have been the main heating devices for thin metal sheets.

On the other hand, in recent years, induction heating using solenoid coils has been used as a method of continuously heating thin metal sheets for annealing thin metal sheets and drying the surface paint of painted thin metal sheets. It is used to heat magnetic steel plates.

As shown in FIGS. 7 and 8, a thin metal plate 2 is continuously run inside a spirally wound solenoid coil 1 of a water-cooled coil, and the magnetic flux 3 generated from the solenoid coil l is This is a method of induction heating using magnetic flux 3 parallel to the thin plate 2.

As shown in FIG. 9, the induction heating by the solenoid coil 1 can efficiently heat the plate almost uniformly in the width direction from room temperature to the magnetic transformation point of about 700°C.

However, when heating above the magnetic transformation point, 500MH
, ~1 MHz, which makes this device expensive, and the conversion efficiency from a commercial frequency power source to a high frequency power source is low, making it uneconomical.

Furthermore, as a conventional heating method for a thin plate made of non-magnetic material such as an aluminum plate, as shown in FIGS. An induction heating method using a transverse coil 8 is used in which the thin metal plate 2 is run between these two inductors 7 and 7, and the magnetic flux 3 generated in the vertical direction by both inductors 7 and 7 is passed through the thin metal plate 2 perpendicularly.

This heating method using the transverse coil 8 can heat steel plates from room temperature to about 1000°C, but the disadvantage is that the temperature distribution in the width direction of the plate is thick (uneven) as shown in Figure 12. was there.

For this reason, a method may be considered in which the solenoid coil 1 is used to heat the material from room temperature to the magnetic transformation point, and the transverse coil 8 is used to heat the material immediately after the magnetic transformation point is reached.

However, in this method, as shown in FIG. 13, when the magnetic transformation point is reached, both ends become non-uniform as shown by curve a, and this non-uniform portion is further enlarged by subsequent heating by the transverse coil 8. , Song # on the exit side!
As shown in b, there was a problem of extremely non-uniformity.

(Problems to be Solved by the Invention) An object of the present invention is to eliminate the above-mentioned drawbacks and to provide an induction heating method for a thin metal plate that can be uniformly heated to a temperature equal to or higher than the magnetic transformation point using an inexpensive device. It is something to do.

[Structure of the Invention] (Means for Solving the Problems) The present invention heats a continuously running thin metal plate to a magnetic transformation point using a transverse coil or a solenoid coil, and then heats it by a solenoid coil after magnetic transformation. It is characterized in that it is heated to a temperature above the magnetic transformation point using a transverse coil after being uniformly heated in the width direction of the plate.

(effect) Next, the operation of the method of the present invention will be explained.

A thin metal plate is continuously transported by transport rollers and first heated from room temperature to the magnetic transformation point using a transverse coil or solenoid coil.

At this time, the temperature distribution in the width direction of the plate near the magnetic transformation point becomes slightly non-uniform on both ends.

Thereafter, when the thin metal plate is held at the magnetic transformation point temperature by induction heating using a solenoid coil, the temperature distribution in the width direction of the plate becomes uniform when the metal plate passes through the solenoid coil.

Thereafter, when the sheet is heated to 900 to 1000° C. with a transverse coil, the temperature distribution in the sheet width direction on the outlet side can be heated almost uniformly to both ends.・In this way, once the metal thin plate reaches the magnetic transformation point, the solenoid coil is used to maintain the temperature at the magnetic transformation point without raising the temperature, making the temperature distribution uniform in the width direction of the sheet, and then increasing the temperature. is an important point.

(Examples) Hereinafter, the present invention will be described in detail with reference to examples shown in the drawings.

FIG. 1 shows an embodiment of the present invention, which includes two transverse coils 8.8, a solenoid coil 1, and two
The transverse coils 8.8 of the stand are arranged in series.

The thin metal plate 2 is continuously conveyed by conveying rollers 9.9, and first heated from room temperature to a magnetic transformation point by transverse coils 8, 8 of FFfPj.

At this time, the temperature distribution in the board width direction at point A is slightly uneven at both ends, as shown by curve A in Figure 3;
B near the magnetic transformation point passing through the transverse coil 8 of the stage? 5. The temperature distribution in the width direction of the plate at curve M is shown in Figure 3.
As shown by B, both ends are largely non-uniform.

Thereafter, when the thin metal plate 2 is induction heated by the solenoid coil l, it reaches the magnetic transformation point temperature, and when kept at this temperature, the temperature distribution in the plate width direction changes as shown in Figure 3 at the zero point passing through the solenoid coil l. It becomes uniform as shown by straight line C.

After this, 900~ with the transverse coil 8.8 in the latter stage
When heated to a final temperature of 1000° C., the temperature distribution in the width direction of the plate at the exit point D becomes almost uniform up to both ends, as shown by the curved line in FIG.

Therefore, since the transverse coil 8 is used to heat the magnetic region below the magnetic transformation point and the non-magnetic region above the magnetic transformation point, the frequency of the power source can be lowered and the cost of the device can be reduced.

FIG. 4 shows another embodiment of the present invention, which includes a front-stage solenoid coil 1 with a narrow coil winding pitch, a rear-stage solenoid coil 1 with a wide coil winding pitch, and three transverse coils 8. ...is arranged in series.

The thin metal plate 2 is continuously conveyed by conveying rollers 9.9, and first heated from room temperature to the magnetic transformation point by the solenoid coil 1 in the previous stage.

At this time, the temperature distribution in the board width direction at point A is shown in curve I in Figure 6.
As shown by IA, it is almost uniform, and the temperature distribution in the sheet width direction at point B on the exit side near the magnetic transformation point is as follows.
As shown by curve 111B in the figure, the temperature at both ends becomes slightly higher.

Thereafter, when the thin metal plate 2 is induction heated by the solenoid coil 1 in the latter stage, it reaches the magnetic transformation point temperature, and when kept at this temperature, more heat is dissipated from the end side, and the solenoid coil 1
At the 0 point passing through, the temperature distribution in the board width direction becomes uniform as shown by #iC in FIG.

After this, the temperature is increased to 900 with the transverse coil 8-...
When heated to ~1000°C, the temperature distribution in the width direction of the plate at point D on the outlet side becomes almost uniform as a whole, although the temperature is slightly lower at both ends, as shown by the curved line in FIG.

In this device, the transverse coil 8 is used to heat the non-magnetic region beyond the magnetic transformation point, so the frequency of the power source is low (and the cost of the device can be reduced).

In the above embodiment, a structure is shown in which the solenoid coils l and 1 are separated into two stages, but the winding pitch of one solenoid coil 1 is widened on the front side and narrowed on the rear side, and the magnetic field is It is also possible to carry out soaking heating at the transformation point.

Further, in the above embodiment, a case has been described in which the solenoid coil 1 and the transverse coil 8 are arranged horizontally, but they may be arranged vertically and the thin metal plate 2 is heated while meandering in the vertical direction.

[Effects of the Invention] As explained above (according to the present invention, a thin metal plate heated to a magnetic transformation point is heated by a solenoid coil and maintained at this temperature, thereby making the temperature distribution in the width direction of the plate uniform). Since the non-magnetic region is heated above the magnetic transformation point using an inexpensive transverse coil, it is possible to obtain an induction heating method for a thin metal plate that can be uniformly heated to a temperature above the magnetic transformation point using an inexpensive device.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of an induction heating device according to an embodiment of the present invention, FIG. 2 is a graph showing the temperature change of a thin metal plate by the device of FIG. 1, and FIG. 3 is a graph showing the width direction of the thin metal plate. 4 is an explanatory diagram showing the configuration of an induction heating device according to another embodiment of the present invention. FIG. 5 is a graph showing the temperature change of a thin metal plate by the device of FIG. 4. The figure is a graph showing the temperature distribution in the width direction of the thin metal plate, Figure 7 is a front sectional view showing the solenoid coil, Figure 8 is a side view of Figure 7, and Figure 9 is the temperature in the width direction of the metal thin plate. Graph showing the distribution, Figure 1O is a front view showing the transverse coil, Figure 11 is a side view of Figure 1O, Figures 12 and 13.
The figure is a graph showing the temperature distribution in the width direction of a thin metal plate. 1... - Solenoid coil 2... Metal thin plate 3 - Magnetic flux 4... U-shaped iron core 5 - Concave full
6-...Water cooling coil 7...Inductor 8...
・Transverse coil 9...Conveyance roller Figure 10 Figure 11 Figure 13

Claims (1)

[Claims] A continuously running thin metal plate is heated to the magnetic transformation point by a transverse coil or solenoid coil, then heated by a solenoid coil at the magnetic transformation point to equalize the temperature in the width direction of the plate, and then heated to above the magnetic transformation point by a transverse coil. A method for induction heating a thin metal plate, which is characterized by heating.