JPH04264385A - Method of heating soft magnetic material with induction heating device - Google Patents

Abstract

PURPOSE:To realize even heating of soft ferrite, of which control is easy, at a low cost by high frequency induction heating method. CONSTITUTION:A high frequency induction heating device consists of a carbon pipe 5, which is located at a heating position inside of an induction coil of the high frequency induction heating device and of which periphery is covered by heat insulating material 6, and a quartz holder 1 for inserting a test piece 2 made of soft magnetic material into the carbon pipe 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of heating a soft magnetic material, such as soft ferrite, to a predetermined temperature using an induction heating device and a carbon pipe in order to measure its material properties.

0002

BACKGROUND OF THE INVENTION Soft magnetic materials are usually used as magnetic core materials for motors and coils. When the magnetic core material has high electrical conductivity, energy loss due to heat generation due to eddy currents generated in the high frequency region becomes a problem.
So-called soft ferrites, typified by -Zn-Fe oxides, have low electrical conductivity and are therefore widely used because such losses are small.

[0003] As a device for heating steel materials and measuring material properties such as thermal expansion characteristics and transformation characteristics, a high frequency induction heating device is generally used because temperature control is easy. Figure 2
is a schematic diagram of this device. A test piece 2 mounted on a quartz holder 1 is heated by induction by a heating coil 3 installed around it. The temperature is measured by thermocouple 4 connected to the test piece.
controlled by

The principle of this device is to utilize the heating phenomenon caused by eddy currents generated by a high-frequency electromagnetic field, so for the reasons mentioned above, it is not suitable for heating materials with low electrical conductivity such as soft ferrite. Not available. The induction heating method also has the property that efficiency decreases when the Curie point is exceeded. Therefore, in the steel heat treatment line,
JP-A-58-221 discloses a heat treatment method that uses induction heating up to the Curie point and switches to direct energization at higher temperatures.
It is disclosed in Publication No. 224. Applying this concept to high-frequency induction heating equipment for material property testing requires complex improvements to electrical systems, temperature control systems, etc. In addition, when soft ferrite is heated using this method, since the Curie point of soft ferrite is quite low at around 120°C, direct current is used for most of the heating, and induction heating is used for uniform heating and easy temperature control. Unable to take advantage of the law.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to solve these problems and realize heating of soft ferrite uniformly and easily controllably at low cost using a high frequency induction heating method.

[0006]

[Means for Solving the Problems] The present invention provides that when a soft magnetic material is heated to a predetermined temperature using a high frequency induction heating device, the outer periphery is made of a heat insulating material at a heating position inside the induction coil of the high frequency induction heating device. A carbon pipe covered with is installed, the soft magnetic material is inserted into the carbon pipe, and the heating temperature of the carbon pipe is adjusted by a high frequency induction heating device so that the soft magnetic material reaches a predetermined temperature. do.

[0007]

[Function] According to the present invention, the carbon pipe is first heated by the induction coil, and the soft magnetic material is indirectly heated through the induction coil, so temperature control is uniform and stable over a wide range of temperatures. It is possible.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram of an improved high frequency induction heating apparatus showing an embodiment of the present invention. A carbon pipe 5 is installed around a quartz holder 1 on which a test piece 2 is attached. The carbon pipe 5 is induction heated by the heating coil 3, and the test piece 2 is indirectly heated by the radiant heat. Since carbon has a high melting point and does not undergo phase transformation under normal usage conditions, stable temperature control is possible over a wide range of temperatures. A heat insulating material 6 is arranged around the outer circumference of the carbon pipe 5 so that the heat of the carbon pipe 5 is efficiently transmitted to the test piece 2 inside. Temperature control is performed by a thermocouple 4' embedded in the carbon pipe 5.

[0009] Using the apparatus shown in FIGS. 1 and 2, Fe2O
3. Molding powder mainly composed of MnO and ZnO,
A soft ferrite test piece created by firing was heated to 1250°C.
A test was conducted in which the sample was heated to . FIG. 4 shows the results of heating this test piece using the conventional apparatus shown in FIG. 2 and measuring the temperature of the test piece with a thermocouple 4. The temperature of the test piece rose to 150°C, but the temperature did not rise above that even if heating was continued.

On the other hand, FIG. 3 shows a test piece 2 of the same material being heated by the high-frequency induction heating apparatus according to the present invention shown in FIG.
This shows the results of measuring the temperature of carbon pipe 5 with thermocouple 4' for comparison and thermocouple 4'' for temperature control. Improvements in the equipment have made it possible to heat soft ferrite to a sufficiently high temperature. Furthermore, since there is no temperature difference between the test piece 2 and the carbon pipe 5, it can be seen that the temperature of the test piece 2 can be controlled by controlling the temperature of the carbon pipe 5.

[0011]

[Effects of the Invention] As is clear from the above explanation, according to the present invention, soft ferrite can be heated to a predetermined temperature and the temperature can be controlled, which is highly effective in measuring and testing various properties of soft ferrite. do.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional device.

FIG. 3 is a graph showing the results of a heating test using the apparatus of the present invention.

FIG. 4 is a graph showing the results of a heating test using the conventional apparatus shown in FIG. 2;

[Explanation of symbols]

1 Quartz holder 2 Test piece 3 Heating coil 4, 4’, 4” thermocouple 5 Carbon pipe 6 Insulation material

Claims (1)

[Claims] Claim 1: When heating a soft magnetic material to a predetermined temperature using a high-frequency induction heating device, a carbon pipe whose outer periphery is covered with a heat insulating material is installed at a heating position inside the induction coil of the high-frequency induction heating device. A method for heating a soft magnetic material, comprising: inserting the soft magnetic material into the carbon pipe, and adjusting the heating temperature of the carbon pipe using a high frequency induction heating device so that the soft magnetic material reaches a predetermined temperature.