JPH06104074A - Method for high frequency induction heating - Google Patents

Abstract

PURPOSE:To enhance the magnetic flux density of a high frequency magnetic field acting on a heating target and increase the generated quantity of heat by using a magnetic circuit formed by a high frequency induction coil and a nonconductive magnetic body. CONSTITUTION:A high frequency induction coil 5 and a nonconductive magnetic body 4 are geometrically arranged so that the high frequency magnetic field made by the high frequency induction coil 5 is guided to the nonconductive magnetic body 4 to form a magnetic circuit. A heating target 3 is put on the magnetic circuit with a space, and high frequency induction heating is carried out. As the nonconductive magnetic body 4, a ferrite bar is used, and as the heating target 3, a stainless plate is used. The magnetic flux density of the high frequency magnetic flux acting on the heating target 3 can be enhanced to increase induction current, and the heating value can be thus increased to raise the heating speed. By changing the form and dimension of the ferrite bar to change the form of the magnetic pole part of the magnetic circuit, the heating target 3 can be locally heated, or a freedom can be given to the positional relation between the heating target 3 and the coil 5.

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a high frequency induction heating method.

[0002]

2. Description of the Related Art Conventional high-frequency induction heating is performed by using an air-core high-frequency induction coil, and magnetic flux is not controlled by forming a magnetic circuit.

Further, since the heating range is determined by the shape of the high frequency induction coil, the heat effect on the object to be heated is wide.

[Problems to be Solved by the Invention]

In the conventional high-frequency induction heating, an air-core high-frequency induction coil is used to induce an induction current in an object to be heated. Therefore, the magnetic flux density that effectively acts on the object to be heated is low, and the amount of heat generated is small because the induced current induced in the object to be heated is small. In high-frequency induction heating using such a conventional air-core high-frequency induction coil, it is necessary to effectively apply the high-frequency magnetic flux generated to obtain a practical heating temperature to the heating target. It was necessary to place the objects to be heated in close proximity.

Further, depending on the shape of the high frequency induction coil,
Since the spatial shape of the generated magnetic flux is determined, it is difficult to limit the heating range of the object to be heated, and the thermal effect affects a wide range of the object to be heated.

It is an object of the present invention to increase the magnetic flux density acting on the object to be heated in high frequency induction heating and increase the amount of heat generated. Further, it is an object of the present invention to perform local high frequency induction heating by concentrating the magnetic flux generated by the high frequency induction coil in a narrow range using a magnetic circuit. Further, it is intended to improve the working environment by giving the degree of freedom to the positional relationship between the high frequency induction coil and the heating object.

[0007]

In order to achieve the above object, the method of high frequency induction heating of the present invention is provided with a magnetic circuit made of a high frequency induction coil and a non-conductive magnetic material. The object to be heated is placed on the magnetic flux concentrated portion.

[0008]

The magnetic circuit made of the non-conductive magnetic material provided in the high frequency induction coil guides the generated high frequency magnetic flux to the object to be heated. For this reason, the magnetic flux density acting on the object to be heated becomes high, and the induced current induced in the object to be heated also becomes large.

By changing the size and shape of the magnetic circuit, the spatial form of the high frequency magnetic flux acting on the object to be heated is changed.

The non-conductive magnetic material forming the magnetic circuit used in this method has a large saturation magnetic flux density, a small magnetic hysteresis loss at high frequencies, and a high Curie point.

[0011]

EXAMPLE As an example of high frequency induction heating, ferrite was used as the non-conductive magnetic material and stainless steel was used as the object to be heated. The distance between the heating target and the high frequency induction coil is 5m
m. The ferrite used here is a soft magnetic material,
At the frequency used in the high frequency induction heating, the one with good magnetic characteristics and the one with small magnetic hysteresis loss was used.

When a ferrite rod is inserted into the high frequency induction coil to guide the high frequency magnetic flux to increase the magnetic flux density and the object to be heated is placed at the end of the ferrite rod, the ferrite rod to be heated as shown in FIG. The part close to the tip of the is red hot, and the temperature is over 800 degrees Celsius.
The conventional method of high frequency induction heating in which the ferrite rod of FIG. 1 is not inserted does not cause red heat. This is because the magnetic circuit composed of the ferrite rod and the high frequency induction coil increased the magnetic flux density of the high frequency magnetic field and increased the induced current induced in the object to be heated.

[0013]

Since the present invention is constructed as described above, it has the following effects.

Since the magnetic flux density of the high frequency magnetic flux acting on the object to be heated can be increased, the induced current induced in the object to be heated becomes large, and the heating speed can be increased.

By changing the shape of the magnetic pole portion of the magnetic circuit made of the non-conductive magnetic material, the shape of the high-frequency magnetic flux acting on the object to be heated can be changed, so that the induced current induced in the object to be heated can be changed. It is possible to limit the flow range of the gas, and local heating becomes possible.

By changing the size and shape of the magnetic circuit made of the non-conductive magnetic material, the high-frequency magnetic flux generated by the high-frequency induction coil can be guided to the required position. It is not necessary to place the high frequency induction coil and the heating target close to each other.

[Brief description of drawings]

FIG. 1 is a diagram showing high frequency induction heating according to a conventional method.

FIG. 2 is a diagram showing a method of high frequency induction heating according to the present invention.

[Explanation of symbols]

 1, 3 heating object 2, 5 high frequency induction coil 4 non-conductive magnetic body 6 red hot part

Claims (1)

[Claims] 1. A method for performing high-frequency induction heating, which comprises focusing a magnetic flux generated by a high-frequency induction coil by using a magnetic circuit composed of a non-conductive magnetic material and a high-frequency induction coil, and performing high-frequency induction heating. That device.