JP2003213329A - Method for induction-heating work - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply and uniformly heat the surface even when a work has large difference to shaft diameters or thicknesses. <P>SOLUTION: In the case of induction-heating the surface of an axial work WA with only an induction-heating coil 10, a portion easily becoming high surface temperature in the axial work WA, is performed to the induction-heating by using a secondary induction-heating coil 20, and the whole surface of the axial work WA, is induction-heated by using both of the induction-heating coil 10 and the secondary induction-heating coil 20. Then, for uniformly performing the induction-heating to the surface, the power of the secondary induction current flowing in the secondary induction-heating coil 20 is adjusted by changing a gap distance between both coils. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an induction heating coil and two
The present invention relates to an induction heating method for a work, in which the surface of the work is induction-heated by using both of the following induction heating coils.

[0002]

2. Description of the Related Art Conventionally, in induction heating a shaft-shaped work WA having a step as shown in FIG. 5, a half-open saddle type induction heating coil 100 is used, and a core 101 is attached to the coil.
I was wearing it. That is, since the large diameter portion WA1 is more easily heated than the small diameter portion WA2 of the shaft-shaped work W, the core 101 is attached to a portion of the induction heating coil 100 that contributes to the heating of the large diameter portion WA1. The balance is adjusted so that the surface of the shaft-shaped work W is uniformly induction-heated.

[0003]

However, in the case of the above-mentioned conventional method, the induction heating coil 100 and the shaft-shaped work W are used.
Unless the gap between A and the amount of core 101 is properly adjusted, the surface of the axial work WA is not uniformly induction-heated, so that a uniform hardened layer cannot be obtained and distortion occurs. There is. Further, in the adjustment by the amount of the gap and the core 101, the adjustment range is narrow and there is a limit, so that it is difficult to obtain a desired hardened layer depending on the shape of the work.

This is not a problem peculiar to the shaft-like work WA having the above-mentioned step, but the surface of the shaft-like work WB having a partially hollow portion and a thick wall as shown in FIG. 3 is induction-heated. The same applies to the case.

Particularly, when the difference in the shaft diameter of the shaft-like work WA or the difference in the wall thickness of the shaft-like work WB is large, the above adjustment is practically impossible, and the so-called one-shot quenching method cannot cope with it. The current situation is that there is no choice but to adopt.

The present invention was devised in view of the above circumstances, and an object thereof is to easily and uniformly heat the surface of a work having a large difference in shaft diameter or wall thickness. An object is to provide a possible method of induction heating of a work.

[0007]

According to the induction heating method for a work of the present invention, when the surface of the work is induction-heated only by the induction heating coil, the portion of the work where the surface temperature is likely to rise is the secondary induction heating coil. A method of induction heating the surface of the work by using both an induction heating coil and a secondary induction heating coil, wherein the surface of the work is uniformly heated by induction heating. By changing the gap length between the induction heating coil and the secondary induction heating coil, 2 flowing to the secondary induction heating coil
The feature is that the magnitude of the secondary induced current is adjusted.

Further, instead of changing the gap length between the induction heating coil and the secondary induction heating coil, the amount of the core mounted on the secondary induction heating coil is changed, or the secondary induction heating coil is changed. Alternatively, the facing area of the coil portion with respect to the induction heating coil may be changed.

The induction heating method for a work according to the present invention is a method for simultaneously inductively heating a plurality of parts on the surface of the work by using both the induction heating coil and the secondary induction heating coil. Of the secondary induction heating coil, the magnitude of the secondary induction current flowing through the secondary induction heating coil is adjusted by changing the gap length between the induction heating coil and the secondary induction heating coil so as to uniformly induce induction heating of a plurality of portions of the induction heating coil. It is characterized by doing so.

Further, instead of changing the gap length between the induction heating coil and the secondary induction heating coil, the amount of the core mounted on the secondary induction heating coil is changed, or the secondary induction heating coil is changed. Alternatively, the facing area of the coil portion with respect to the induction heating coil may be changed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an induction heating method for a work according to the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram of an induction heating coil and a secondary induction heating coil for explaining the same method, FIG. 2 is a diagram for explaining a method of adjusting the magnitude of the secondary induction current, and FIG. 3 is another type. FIG. 4 is a sectional view of the work of FIG. 4, and FIG. 4 is a view corresponding to FIG. 1 for explaining a modified example of the method.

In the figure, 10 is a semi-open saddle type induction heating coil, and 20 is a semi-open saddle type secondary induction coil. Unlike the secondary induction coil 20, the induction heating coil 10 is connected to a high frequency power source (not shown). That is, the induction heating coil 1
When a high-frequency current (primary induction current) flows in 0, the secondary induction current flows in the secondary induction coil 20 in the direction opposite to the direction of the primary induction current due to electromagnetic induction. In addition,
A mechanism for rotating the shaft-shaped work WA is not shown.

By using both the induction heating coil 10 and the secondary induction coil 20 as described above, the surface of the shaft-shaped work WA is induction-heated while being rotated as follows.

That is, when the surface of the work is induction-heated only by the induction heating coil, the entire axial work WA (large diameter portion W
A1 and the small-diameter portion WA2) are induction-heated by the induction heating coil 10, while a portion of the shaft-shaped work WA where the surface temperature is likely to rise, here, the small-diameter portion W2 is provided with a secondary induction heating coil 20 for induction Try to heat. Then, the secondary induction current flowing through the secondary induction heating coil 20 is changed by changing the gap length G between the induction heating coil 10 and the secondary induction heating coil 20 so that the surface of the shaft-shaped work WA is uniformly induction-heated. The magnitude of I is adjusted (see FIG. 2A).

Specifically, a spacer (not shown) provided between the induction heating coil 10 and the secondary induction heating coil 20 is exchanged to change its thickness, or the induction heating coil 10 has two
It is advisable to provide a mechanism for supporting the next induction heating coil 20 with a function capable of arbitrarily adjusting the gap length G.

When the gap length G between the induction heating coil 10 and the secondary induction heating coil 20 is changed, the magnitude of the secondary induction current I induced in the secondary induction heating coil 20 changes, and with this change. The amount of induction heating generated in the small diameter portion W2 of the axial work WA changes. Therefore, the surface of the shaft-shaped work WA can be uniformly induction-heated over the large diameter portion W1 and the small diameter portion W2.

Instead of changing the gap length G between the induction heating coil 10 and the secondary induction heating coil 20, the amount of the core 21 such as farite attached to the secondary induction heating coil 20 may be changed (see FIG. B)), or the secondary induction heating coil 20 may be selected to change the facing area of the coil portion with respect to the induction heating coil 10 (FIG. 2).
(C)). Even in these cases, since the magnitude of the secondary induction current I flowing through the secondary induction heating coil 20 changes, the same result as above is obtained. Moreover, the magnitude of the secondary induced current I may be adjusted by combining these.

In the conventional method, when the amount of the gap or the core is adjusted, the amount of induction heating generated not only in the small diameter portion W2 of the shaft-shaped work WA but also in the large diameter portion W1 changes, which makes adjustment difficult. It was However, in the case of the method of the present invention, even if the gap length G or the like is changed, the amount of induction heating generated in the large-diameter portion W1 of the shaft-shaped work WA hardly changes.
The adjustment itself becomes much easier than the conventional method. In particular, even when the difference in the shaft diameter of the shaft-shaped work WA or the difference in the wall thickness of the shaft-shaped work WB is large as shown in FIG. 3, the above-mentioned adjustment can be easily performed, and the moving quenching method is not used. It becomes possible to perform uniform induction heating on the surfaces of these works.

Therefore, it becomes possible to form a uniform hardened layer on the surface of the shaft-shaped work WA or WB, and there is no fear of distortion.

In the above example, the axial work WA (or W
Although the method of induction heating the surface of B) was used, as shown in FIG. 4, both the induction heating coil 10 and the secondary induction heating coil 20 were used, and portions A and B on the surface of the axial work WC were used. Induction heating may be performed at the same time.

That is, the surfaces of the portions A and B of the shaft-shaped workpiece WC are induction-heated by the induction heating coil 10, while the surface of the portion C has a current flowing in the opposite direction.
The next induction heating coil 20 is used to prevent induction heating.

When the method of the present invention is used for such partial hardening, the surfaces of the parts A and B can be simultaneously induction-heated without using the moving hardening method or the like. Further, since the magnitude of the secondary induction current I flowing through the secondary induction heating coil 20 can be adjusted in the same manner as described above in the same manner as described above, even if the size of the shaft-shaped workpiece WC changes, it is appropriate. It is possible to adjust, and there is an advantage that workability is good.

The method of induction heating of the work according to the present invention is not limited to the above embodiment, and for example, the coil may be appropriately selected according to the type of work. In addition, the surface of the work may be heated uniformly by combining the induction heating coil and a plurality of secondary induction heating coils and adjusting the magnitude of the secondary induction current as described above.

[0024]

As described above, in the induction heating method for a work according to the present invention, both the induction heating coil and the secondary induction heating coil are used to adjust the secondary induction current flowing through the secondary induction heating coil. Since the surface of the work can be induction-heated uniformly, the adjustment itself becomes easy,
It is possible to easily uniformly heat the surface of a work having a large difference in shaft diameter or wall thickness. Moreover, since the method of the present invention also enables induction heating of a plurality of parts of the work at the same time, there is a merit in work efficiency.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of an induction heating method for a work according to the present invention, which is an explanatory diagram of an induction heating coil and a secondary induction heating coil.

FIG. 2 is a diagram for explaining a method of adjusting the magnitude of a secondary induced current.

FIG. 3 is a cross-sectional view of another type of work.

FIG. 4 is a diagram corresponding to FIG. 1 for explaining a modified example of the method.

FIG. 5 is an explanatory diagram of an induction heating coil for explaining a conventional method.

[Explanation of symbols]

10 induction heating coil 20 secondary induction coil WA, WB axial work

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 6/44 H05B 6/44

Claims (6)

[Claims] 1. When induction heating the surface of a work only with an induction heating coil, a portion of the work where the surface temperature is likely to rise is induction heated using a secondary induction heating coil. A method of inductively heating the surface of the work using both of a secondary induction heating coil, wherein the induction heating coil and the secondary induction heating coil are provided to uniformly induction heat the surface of the work. An induction heating method for a work, characterized in that a magnitude of a secondary induction current flowing through the secondary induction heating coil is adjusted by changing a gap length. 2. The induction heating method for a work according to claim 1, wherein instead of changing a gap length between the induction heating coil and the secondary induction heating coil, a core to be mounted on the secondary induction heating coil is used. An induction heating method for a work, characterized in that the amount is adjusted. 3. The method for induction heating of a work according to claim 1, wherein the secondary induction heating coil is selected instead of changing the gap length between the induction heating coil and the secondary induction heating coil. An induction heating method for a work, characterized in that a facing area of a coil portion with respect to the induction heating coil is changed. 4. A method for simultaneously inductively heating a plurality of parts on the surface of a work by using both an induction heating coil and a secondary induction heating coil, wherein the plurality of parts on the surface of the work are uniformly induction heated. To this end, the magnitude of the secondary induction current flowing through the secondary induction heating coil is adjusted by changing the gap length between the induction heating coil and the secondary induction heating coil. Induction heating method for work. 5. The method for induction heating a work according to claim 4, wherein instead of changing a gap length between the induction heating coil and the secondary induction heating coil, a core to be mounted on the secondary induction heating coil is used. An induction heating method for a work, characterized in that the amount is adjusted. 6. The induction heating method for a work according to claim 4, wherein the secondary induction heating coil is selected instead of changing the gap length between the induction heating coil and the secondary induction heating coil. An induction heating method for a work, characterized in that a facing area of a coil portion with respect to the induction heating coil is changed.