JPH0665120B2 - Induction heating method with crossed magnetic field - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to induction heating of a belt-shaped conductive object with a cross-field type induction heater. The present invention relates to a method of providing a substantially uniform heating action.

[Prior art]

Conventionally, the cross magnetic field type induction heater shown in FIG. 3 has been used, but a conductive object to be heated (for example, a strip-shaped copper material) 1
A pair of crossed magnetic field type induction heaters 2A and 2B are arranged for heating from above and below for the purpose of annealing or the like.

Exciting coils 3A to 3D are wound around the respective magnetic poles of the heaters 2A and 2B, and an alternating magnetic field is generated from the magnetic poles by an alternating current applied to the coils 3A to 3D. Object to be heated 1
Is placed in this alternating magnetic field, an eddy current of 4A
4D flows, this eddy current generates surreal heat,
The belt-shaped conductive object 1 itself is heated.

[Problems to be solved by the invention]

The above-mentioned cross-field type induction heater has a drawback that the edge portion and the center portion of the belt-shaped conductive object to be heated are not uniformly heated because a so-called edge effect occurs during heating. That is, as shown in FIG. 4, the temperature in the lateral width W direction of the belt-shaped conductive object to be heated 1 is a portion P where the magnetic poles face each other.
_{In 1} , the temperature at the edges is higher than at the center (Fig. 4 (a)),
On the contrary, in the groove portion P _{2 having} no magnetic pole, the central portion has a higher temperature (FIG. 4B) than the end portions. And
When the object to be heated 1 continuously moves in the direction of arrow F, as shown in FIG. 4C, the center line X of the width between the central portion and the end portion and the portion R where the temperature drops to the target position Therefore, there is a problem that uniform heating is not achieved, and there is a risk that distortion due to the temperature difference may occur in the article to be heated 1 when applying necessary energy to the belt-shaped conductive article to be heated.
In order to eliminate this distortion, (a) to reduce the amount of heat received per unit time, the magnetic flux of the cross magnetic field is weakened to reduce the transport speed of the article to be heated (1) induction heaters 2A, 2B for cross magnetic field generation.
It is conceivable that the thermal energy is gradually supplied to the object to be heated 1 by means such as increasing the length of the magnetic field and weakening the magnetic flux of the cross magnetic field. It takes too much time to give it to the object 1, and the means of (b) has a drawback that the induction accelerator becomes large and expensive.

[Means for solving problems]

The present invention is intended to eliminate such conventional drawbacks,
The gist of the invention is to pass a strip-shaped conductive object to be heated a plurality of times in the magnetic field of the cross magnetic field.

[Action]

The thermal energy required by the belt-shaped conductive object to be heated is given in a plurality of times.

〔Example〕

Hereinafter, the illustrated embodiment will be specifically described. First
The figure is a front view showing a specific configuration of the present invention, and the same components as those in FIG. 3 are denoted by the same reference numerals, and the description thereof will be omitted. In FIG. 1, K ₁ and K ₂ are rollers, which are located outside both sides of the induction heaters 2A and 2B facing each other, and engage a belt-shaped conductive object 1 to be heated. Obtain the three-layer state of object 1. Then, the conductive object to be heated 1 is formed into a strip shape in a three-layer state.
Are arranged between the magnetic flux generating surfaces of the induction heaters 2A and 2B which face each other.

In the above-mentioned configuration, the belt-shaped conductive object to be heated 1 is moved three times between the magnetic flux generating surfaces of the induction heaters 2A and 2B which face each other, and is subjected to induction heating based on the cross magnetic field at each shift. However, if the required magnetic flux in Fig. 3 is the same, the electromagnetic energy applied per unit time is 1 /
Is 3. Therefore, the belt-shaped conductive object 1 to be heated is supplied with heat energy gentler than the conventional one.

It should be noted that the present invention is not limited to the embodiment shown in FIG. 1, and for example, K ₁₁ , K ₁₂ , and K _{13 as} shown in FIG.
Alternatively, the belt-shaped conductive object 1 to be heated may be guided, and the object 1 to be heated may be arranged in two layers between the magnetic flux generating surfaces of the induction heaters 2A and 2B.

〔effect〕

As described above, the induction heating method using the crossed magnetic field according to the present invention continuously provides a belt-shaped conductive object to be heated between the magnetic flux surfaces of a pair of induction heaters whose magnetic pole surfaces are opposed to each other. It is arranged in a plurality of layers so that the strip-shaped conductive object to be heated is passed a plurality of times between the magnetic pole faces of the pair of induction heaters. Based on such an induction heating method, (i) supplying necessary thermal energy to the belt-shaped conductive object to be heated without lowering the feed rate of the belt-shaped conductive object to be heated without increasing the temperature gradient. You can

(B) Since the necessary thermal energy is applied in multiple steps, electromagnetic vibration, thermal strain, etc. are reduced for the belt-shaped conductive object to be heated, and the heating temperature distribution in the belt-shaped conductive object to be heated is reduced. Be homogenized.

It is possible to increase the substantial length of the induction heater when supplying the heat energy of a certain amount or less per unit time to the conductive object to be heated in the form of a band.

There are features such as.

[Brief description of drawings]

1A and 1B are a side view and a plan view showing the structure of the crossed magnetic field type induction heater according to the method of the present invention, FIG. 2 is a side view showing another structure of the present invention, and FIGS. A side view and a plan view showing the structure of a conventional crossed magnetic field type induction heater, FIG.
(B) and (c) are graphs showing the temperature distribution of the object to be heated by the device of FIG. 1 ...... conductive object to be heated 2A, 2B ...... induction heater _{K 1, K 2, K 11} , K 12, K 13 ...... roller

Claims (1)

[Claims] 1. A conductive object to be heated in the form of a strip is continuously passed between the magnetic pole surfaces of a pair of induction heaters whose magnetic pole surfaces are opposed to each other in a plurality of layers. And an induction heating method using a cross magnetic field.