JPH10328744A - High-frequency heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the high-frequency heating device heating uniformly and efficiently. SOLUTION: An upper heating coil 2 shaped along the front surface of a U-tube to be heated, a lower heating coil in which a first coil 3a shaped along the rear surface of the U-tube, a second coil 3b shaped along the inside surface of the U-tube and a third coil 3c shaped along the outside surface of the U-tube have been connected in arbitrary order, plural cores 7 made of a magnetic material, whose groove parts are inserted into the bend parts of the second coil 3b, and a high-frequency generator connected to the upper heating coil and the lower heating coil, are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency heating apparatus applied to close-contact bending (extremely small radius bending) of a thermal power plant boiler tube or the like.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 14, an operator heats a U-shaped tube 4 of a boiler tube to be bent using a heating burner, and raises the temperature to a processing temperature. Then, a press-contact bending (minimum R bending) is performed from both sides by the bending press 12. Next, it was pressed from above and below with a bending correction press 13 to correct the bent portion so as to have a clean curve.

[0003]

In the prior art, since the manual operation is performed by a heating burner, it is difficult to control the heating temperature, the temperature distribution becomes nonuniform, and the bent portion of the contact bending by the next step press is used. There was a problem that the quality was not stable.

[0004]

The present invention employs the following means to solve the above-mentioned problems.

That is, as a high-frequency heating device, an upper heating coil having a shape along the upper surface of the U-tube to be heated, a first coil having a shape along the lower surface of the U-tube, and an inner surface of the U-tube. A lower heating coil in which a second coil having a shape along the shape and a third coil having a shape along the outer surface of the U-shaped tube are connected in an arbitrary order, and a groove portion is inserted into a bent portion of the second coil. A plurality of cores made of a magnetic material and high frequency generating means connected to the upper heating coil and the lower heating coil are provided.

In the above invention, a U-tube to be heated is set on the lower heating coil. Next, the upper heating coil is U
It is set above the pipe. Next, the groove of the magnetic core is inserted and set in the bent portion of the second coil along the inner surface of the U-shaped tube.

In this state, when a high-frequency current flows through the upper and lower heating coils by the action of the high-frequency generating means, the U-tube is heated substantially uniformly. In particular, the inner curved portion that is hard to be heated is more efficiently heated by the characteristic of the magnetic core that concentrates the magnetic flux density.

In this manner, the U-shaped tube is easily and uniformly heated to a predetermined temperature suitable for bending.

[0009]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. 1 to 5, an upper heating coil 2 is provided along the upper surface of a U-shaped tube 4. U-tube 4
A first coil 3a along the lower surface of the U-tube, a second coil 3b along the inner surface of the U-shaped tube 4, and a third coil 3c along the outer surface of the U-shaped tube 4 are provided. These are connected in order with the second coil, the first coil, and the third coil, and become the lower heating coil 3.

As shown in FIG. 6, a lower heating coil 3 is horizontally arranged on a work table 10. Further, an upper heating coil 2 is arranged above the upper heating coil 2 via the vertical moving device 1. The work table 10 has a high-frequency generator 5 and a matching board 6,
The upper and lower heating coils 2 and 3 are connected to these.

In the above description, the second coil, the first coil, and the third coil are connected in this order, but the connection order may be arbitrary.

The heating of the U-shaped tube 4 is performed as follows. First, as shown in FIGS. 7 and 8, the U-shaped tube 4 is set on the lower heating coil 3. The U-shaped tube 4 is set at equal intervals with each coil as shown in FIGS. Also the second
At the bent portion of the coil 3b, three magnetic material (silicon steel plate) cores 7 each having a groove a on one side face are arranged so as to insert the groove a from the inside into the second coil 3b as shown in FIG. ing.

Next, the upper heating coil 2 is moved by the vertical moving device 1.
Are arranged above the U-shaped tube 4 at predetermined intervals. The high-frequency current flows through the upper and lower heating coils 2 and 3 by the action of the high-frequency generator 5 and the matching board 6, and the U-tube 4 is heated almost uniformly. In particular, the inner bent portion that is hard to be heated is more efficiently heated by the characteristic of the magnetic core 7 that concentrates the magnetic flux density.

In this manner, the U-tube is easily and uniformly heated to a predetermined temperature suitable for bending.

FIGS. 9 and 10 show the measurement results of the heating temperature according to the present embodiment. FIG. 9 shows the shape and measurement position of the U-shaped tube 4 to be heated. FIG. 10 shows the temperature at each position to. It can be seen that the temperature difference between the top of the highest bend start portion and the inside of the lowest bend base is 90 ° C., and the heating time is about 5 minutes, so that the workpiece is almost uniformly heated to the processing temperature (about 1100 ° C.). Note that the time axis of each curve is shifted for ease of viewing.

For comparison, FIG. 13 shows the measurement results when a solenoid type heating coil 11 as shown in FIGS. 11 and 12 is used. A temperature difference of 360 ° C. occurred between the outside of the highest bend and the outside of the lowest bend.

Also in this curve, the time axes are shifted, similarly to the above.

[0018]

According to the present invention as described above,
The U-tube to be heated is efficiently and uniformly heated to the bending temperature.

[Brief description of the drawings]

FIG. 1 is a perspective view of a high-frequency heating coil according to an embodiment of the present invention.

FIG. 2 is a plan view of a high-frequency heating coil unit having the same configuration.

FIG. 3 is an AA view of FIG. 2 of the same embodiment.

FIG. 4 is a BB view of FIG. 2 of the same embodiment.

FIG. 5 is a CC view of FIG. 2 of the same embodiment.

FIG. 6 is an overall configuration diagram of the same embodiment.

FIG. 7 is an operation explanatory view of the same embodiment.

FIG. 8 is an operation explanatory view of the same embodiment.

FIG. 9 is an operation explanatory view of the same embodiment.

FIG. 10 is an operation explanatory view of the same embodiment.

FIG. 11 is an operation explanatory view of the same embodiment.

FIG. 12 is an operation explanatory view of the same embodiment.

FIG. 13 is an operation explanatory view of the same embodiment.

FIG. 14 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vertical movement apparatus 2 Upper heating coil 3 Lower heating coil 3a 1st coil 3b 2nd coil 3c 3rd coil 4 U-tube 5 High frequency generator 6 Matching board 7 Core 11 Heating coil 12 Close bending press 13 Bending correction press

Continuation of the front page (72) Inventor Hideo Saijo 6-2-22 Fujimi, Tsurugashima-shi, Saitama Prefecture Fuji Electric Machine Co., Ltd.

Claims (1)

[Claims] 1. An upper heating coil having a shape along the upper surface of a U-tube to be heated, a first coil having a shape along a lower surface of the U-tube, and a shape having an inner surface of the U-tube. A lower heating coil in which a second coil and a third coil having a shape along the outer surface of the U-shaped tube are connected in an arbitrary order; and a plurality of magnetic materials in which a groove is inserted into a bent portion of the second coil. A high-frequency heating device comprising a core and high-frequency generating means connected to the upper heating coil and the lower heating coil.