JPH0355790A - High-frequency heating method and its device - Google Patents

Abstract

PURPOSE:To increase magnetic flux caused by a coil and make magnetic effect efficient by generating induced current at a heated part, which is heated. CONSTITUTION:A hollow cylindrical iron core 11 has both ends provided with annular flange portions 12 to be concentric and integral with the iron core 11, and has the outer periphery wound with an insulation-coated conductive wire 13 to form a coil portion 14, and the wire 13 at the coil portion 14 has both ends connected to a power supply 15 which generates high-frequency power. An insertion rod 17 is clasped, the coil portion 14 is inserted into a tubular material 16 and high-frequency power is supplied from the power supply 15 to the coil portion 14, then to cause induced eddy current to flow in the inside surface part of the tubular material 16 along the outer periphery of the coil portion 14 and the outer peripheries of the flange portions 12, Joule heat to be generated, necessary positions to be heated and preset heat treatment to be performed.

Description

[Detailed Description of the Invention] Industrial Application Fields The present invention relates to a high-frequency heating method and apparatus that mainly performs heat treatment such as hardening and annealing on the surface portion of metal, and particularly relates to a high-frequency heating method and apparatus for heat treatment such as hardening and annealing the surface portion of metal. It is suitable for use in heat treatment.

Conventional technology> Conventionally, heat treatments such as hardening and annealing of structures consisting of piping made of steel pipes and various valves incorporated therein usually involve heating the outer surface of the structure at the necessary locations. It is done by doing.

In order to carry out such heat treatment, for example, a combustion flame of a combustible gas such as acetylene or propane may be directly blown onto the part of the outer surface of the structure that requires heating, or an electric heater may be placed nearby and the area heated by its radiant heat may be used. Measures are being taken to: Alternatively, by winding a conductive wire along the outer surface of the structure to form a coil, and passing high-frequency power through the coil, an induced current is generated in the outer surface portion along the coil, and the resulting Joule heat heats the structure. There are other methods.

Problems to be Solved by the Invention In structures made of steel pipes and the like, it is often desirable to heat-treat mainly the inner surface portion of the structure. In such cases, if conventional heat treatment methods, such as heating using a combustion flame of combustible gas, are used, combustion will be maintained in a highly obstructed area such as the inside of the flange pipe, resulting in oxygen deficiency, explosion, etc. It is dangerous and extremely difficult to employ. Furthermore, electric heaters inherently have the disadvantage of poor heating efficiency, and it is difficult to heat the required thickness within the required range in a substantially concentrated manner, resulting in increased strain and material deterioration. The problem was that it was easy to invite. Also,
Conventionally, in heating by induced current, the coil that generates the induced current in the heated part is a coreless coil that surrounds the entire structure including the heated part. There was a problem in that it was extremely difficult to arrange the heater along the same line and accurately close to the heated part.

<Means for Solving the Problems> The high-frequency heating method according to the present invention involves bringing a coil formed around an iron core into close contact or substantially close contact with a portion to be heated, and applying high-frequency power to the coil. The high-frequency heating device according to the present invention is characterized in that an induced current is generated in the heated portion to heat the heated portion, and the high-frequency heating device according to the present invention includes an iron core having a shape portion along the heated portion, and the iron core. The device is characterized by comprising a coil formed by winding a conductive wire around the coil, and a power source that supplies high-frequency power to the coil.

<Function> A coil formed around the iron core is brought into close contact with or substantially close to the heated portion, and by passing high frequency power through the coil, an induced current is generated in the heated portion and the heated portion is heated. heat up. Since the iron core has a shaped portion that follows the heated portion, it is possible to heat the heated portion by generating an induced current extremely efficiently and in a limited manner.

tI! i Example> Hereinafter, an example in which the high-frequency heating method and apparatus according to the present invention are applied to heat treatment of the inner surface portion of a pipe material such as a steel pipe will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of the high-frequency heating device according to the embodiment B inserted into the pipe material, FIG. 2 is a perspective view of only this high-frequency heating device, and a side view of the coil portion in FIG. A sectional view and a front view are shown in FIGS. 3 and 4, respectively. That is, as shown in these figures, a ring-shaped flange portion 12 is formed at each end of the hollow cylindrical iron/core 11 and is concentric with and integral with the iron core 11. reactor.

An insulated conductor 13 is spirally wound around the outer periphery of the iron core 11 to form a coil portion 14, and both ends of the conductor 13 of the coil portion 14 are connected to a power source 15 that generates high-frequency power. Teiro. Also, the flange part 12 on the right side in the figure
As shown in FIG. 1, a volatilization rod 17 is fitted in order to insert the coil portion into the heated spot in the tube 16 having a circular cross section.

Therefore, hold the insertion rod 17 and insert the coil portion 14 into the tube material 16.
Insert it inside and guide it to the area where heating is required.

After that, if high-frequency power is supplied from the power source 15 to the coil portion 14, the outer circumferential portion of the coil portion 14 and the flange portion 12
An induced eddy current flows through the inner surface of the tube material 16 along the outer periphery of the tube due to electromagnetic induction, and Joule heat is generated as a result of this, heating the area that requires heating and performing predetermined hardening, annealing, etc. Heat treatment is performed.

In this way, in the present invention, since the coil part 14 is formed firmly with the iron core 11ζζ wound, it is extremely advantageous when inserting into the inside of the pipe material 16, etc., compared to the conventional coreless coil. In addition, since the iron core 11 located inside the coil portion 14 has the effect of greatly increasing the magnetic flux generated by the coil portion 14, the heating power of the heating device is greatly improved.

The flange portion 12, which is made of the same material as the iron core 11, also has the effect of increasing magnetic flux in the same way as the iron core 11, and the flange portion 12 is in close contact with or approximately on the inner peripheral surface of the tube material 16. It has an outer diameter that allows close contact. For this reason, the magnetic flux can be applied extremely efficiently only to the inner surface portion that requires heating, which further improves the heating effect.When the iron core 11 and the flange portion 12 are made of shaped or zigzag materials, high-frequency power is applied to magnetize them. In order to minimize the power consumed as a result of this, so-called iron loss, a silicon steel plate, etc. is used when applying a relatively low frequency band, and a ferrite core, etc. is used when applying a relatively high frequency band. and is suitable.

Further, by adjusting the frequency of the power applied to the coil portion 14 according to the heat treatment conditions, the amount of heat generated and the heating area (mainly the depth from the heating surface) can be freely changed.

By the way, in this embodiment, the part to be heated is the inner surface of the structure, that is, the pipe material 16, but of course it may be the inner surface of a structure having various other shapes. Alternatively, the shape of the flange portion 12 or a portion of these members may be formed so that it can be in close contact with or substantially in close contact with the shape of various structures, and furthermore, it may be formed so as to follow the outer surface of the structure. Of course, the outer surface portion may also be heated. Therefore, the flange portion 12 does not necessarily have to have it. Furthermore, in order to cool the iron core 11 or the flange portion 12, a cooling pipe passage passing through these members may be provided, and a cooling liquid or the like may be flowed into the cooling pipe passage.

Effects of the Invention According to the present invention, by bringing a coil formed around an iron core in close contact or substantially close contact with a heated portion, and by supplying high frequency power to the coil from a power source,
Since it was decided to heat the heated part by generating an induced current in the heated part, the iron core around which the coil is wound greatly increases the magnetic flux generated by the coil, and the iron core and coil are connected to the heated part. By positioning the heating element very close to the heating element, the magnetic field can be applied more efficiently, thereby achieving efficient and limited heating of the heated portion.

[Brief explanation of drawings]

1 and 2 are schematic perspective views showing one embodiment of the present invention, FIG. 3 is a schematic cross-sectional view of the structure of a coil portion, and FIG. 4 is a view taken in the direction of arrow A in FIG. 3. In the drawing, 11 is the iron core, 12 is the flange, 13 is the conductor,
14 is a coil portion, 15 is a power source, 16 is a tube material, and 17 is an insertion rod.

Claims (2)

[Claims] (1) By bringing a coil formed around the iron core into close contact or substantially close contact with the heated part and by applying high frequency power to the coil, an induced current is generated in the heated part and the heated part is heated. A high frequency heating method characterized by heating. (2) A high-frequency heating device comprising: an iron core having a shaped portion that follows the heated portion; a coil formed by winding a conducting wire around the iron core; and a power source that supplies high-frequency power to the coil.