JP3565595B2 - Induction heating coil - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an induction heating coil, and is particularly useful when applied to a case where a long object to be heated, such as a shaft member or a pipe having a finite length, is heated statically.
[0002]
[Prior art]
Induction heating is a heating method of heating an object to be heated by passing an induction current through the object to be heated, which is a conductor inserted into the internal space, by a heating coil wound in a cylindrical shape.
[0003]
FIG. 3 shows an induction heating coil according to the prior art used for this induction heating. As shown in FIG. 1, the coil conductor 1 is wound uniformly around the cylinder 3 such as a ceramic sleeve, which is a heat-resistant insulating material, in a state where the insulating material 2 is wound around the outer periphery thereof in the axial direction. The outer insulating material 4 is fixed by winding the outer insulating material 4 around the outer periphery of the material 2. At this time, the coil conductor 1 generally has a water passage hole as a hollow portion for flowing cooling water. That is, the coil conductor 1 is formed of, for example, a square copper pipe.
[0004]
The object to be heated 5 is heated by passing a high-frequency current through the coil conductor 1 while being inserted into the internal space of the cylinder 3 and passing an induced current through the object to be heated 5.
[0005]
[Problems to be solved by the invention]
In the induction heating coil, in particular, when the object to be heated 5 is a long object such as a shaft member or a pipe having a finite length, and when the object is heated statically, the temperature distribution in the longitudinal direction of the object to be heated 5 As shown in FIG. 4, the distribution becomes convex in which the distribution is low at both ends and high at the center, and uniform heating cannot be performed. This induction heating coil shown in FIG. 3 is the spacing g ₀ between the coil conductor 1 adjacent to each other in the axial direction is constant, the magnetic flux is because larger induced current flows in the central portion to be dense.
[0006]
An induction heating coil as shown in FIG. 5 has been proposed to improve such uneven heating. As shown in the figure, in this induction heating coil, a spacer 6 which is an annular insulating member is interposed between coil conductors 1 adjacent at a central portion, and a coil 6 at both ends is disposed between the coil conductors 1 at the central portion. by securing a large interval g ₂ with respect to the spacing g ₁ between the conductor 1 is obtained by less than both end portions of the winding density of the coil in the central portion. According to this induction heating coil, as shown in FIG. 6, the temperature distribution in the longitudinal direction of the article 5 to be heated is substantially uniform.
[0007]
However, in the induction heating coil shown in FIG. 5, a portion corresponding to the spacer 6 of the object 5 to be heated is not heated, so that not only a temperature difference from other portions occurs but also the spacer 6 flows through the coil conductor 1. Since it is hard to receive the cooling action of the cooling water, deterioration of characteristics such as mechanical strength and insulation due to temperature rise is caused, and a new problem that the life is shortened is caused. In addition, volume shrinkage occurs due to the above-described characteristic deterioration, and in this case, the coil conductor 1 and the insulating material 2 are insufficiently fixed, and coil vibration is likely to occur.
[0008]
An object of the present invention is to provide an induction heating coil that can uniformly heat an object to be heated without using a special spacer or the like in view of the related art.
[0009]
[Means for Solving the Problems]
The structure of the first invention for achieving the above object is as follows.
In an induction heating coil configured by winding a coil conductor having an insulating material wound around the outer periphery thereof in the axial direction of a cylindrical heat-resistant insulating material,
The coil conductor has a hollow portion serving as a water passage hole for flowing cooling water,
Combine a plurality of types of coil conductors with different widths so that the winding density at the center is low, and the winding density on both the left and right sides with respect to the center in the axial direction is equal, The distance between the coil conductors is the same.
[0011]
The second invention is
The first invention is characterized in that a temperature sensor is embedded in a portion where the width of the coil conductor changes.
[0012]
The third invention is
In the first or second invention, the heat-resistant insulating material is characterized in that a cylindrical ceramic sleeve is inserted into the inner periphery of a cylindrical member of castable cement.
[0013]
[Action]
ADVANTAGE OF THE INVENTION According to this invention of the said structure, a to-be-heated object can be uniformly heated so that a temperature distribution may become constant along the longitudinal direction.
[0014]
In particular, according to the second aspect , when measuring the coil temperature, this measurement can be performed without having the most influence on the uniformity of heating.
[0015]
According to the third invention, it is possible to prevent the broken pieces of the castable cement from falling off.
[0016]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0017]
FIG. 1 is a longitudinal sectional view showing an induction heating coil according to the present embodiment. As shown in FIG. 1, the coil conductor 11 is wound around a castable cement cylinder 13, which is a heat-resistant insulating material, in an axial direction with an insulating material 12 wound around the outer periphery thereof. It is fixed by winding an outer peripheral insulating material 14 around the outer periphery.
[0018]
The coil conductor 11 in the present embodiment is formed of a rectangular copper pipe as shown in FIG. 2 and particularly shows this portion, and has a hollow portion 11a serving as a water passage hole for flowing cooling water. It is.
[0019]
As the insulating material 12, a tape such as an epoxy resin-impregnated glass fiber is suitable. Further, the outer peripheral insulating material 14 is generally formed by winding a resin-coated sheet a plurality of times and solidifying it.
[0020]
Further, the coil conductor 11 in the present embodiment is composed of two types of narrow and wide square copper pipes having a relationship of w ₁ <w _2. Wound around both ends so as to be symmetrical about the center. Thus, together with the close coiled portion II winding density on both sides is large open coiled portion I of the wound density is small central portion is formed, the interval g ₃ between the coil conductor 1 adjacent to each other in the axial direction over the entire coil And are formed to be the same.
[0021]
The cylindrical ceramic sleeve 15 is inserted into the inner periphery of the cylinder 13 and forms a heat-resistant insulating material together with the cylinder 13. At this time, the ceramic sleeve 15 prevents the broken pieces of the cylinder 13 of castable cement from falling off.
[0022]
The temperature sensor 16 detects the temperature of the ceramic sleeve 15. The temperature sensor 16 is inserted into a portion where the width of the coil conductor 11 changes, penetrates the cylinder 13, and the tip end faces the outer peripheral surface of the ceramic sleeve 15. At this time, the temperature sensor 16 employs a fiber radiation thermometer, so that there is no induction trouble. Further, the insertion portion of the temperature sensor 16 may be formed in a space where the width of the coil conductor 11 is changed at a portion where the width of the coil conductor 11 changes, or a space obtained by providing a cutout on the wide side. it can.
[0023]
The induction heating coil 11 is housed in a frame (not shown) having a rectangular cross section to form a component of the induction heating furnace. The gap between the coil conductors 1 is removed and fixed by pressing from the side toward the center. That is, the push screws 17a, 17b, 17c, and 17d are partially screwed into female screw portions (not shown) on the frame side, and the tips move toward the center of the induction heating coil by rotating them. I do. Further, the induction heating coil is fixed to the frame by a plurality of jack bolts (not shown) arranged at regular intervals in the circumferential direction. That is, each jack bolt is screwed into a female screw portion (not shown) on the frame side and can be moved in the radial direction. It is configured to support the coil.
[0024]
According to the above embodiment, the center portion of the induction heating coil is the loosely wound portion I, and both ends are the densely wound portion II, and furthermore, as shown in the prior art shown in FIG. The object to be heated 5 is heated even more uniformly than in the case of FIG. At the same time the gap g ₃ between the coil conductor 1 also takes place uniformly cool the respective portions by the cooling water because it is constant. Therefore, the specific portion does not deteriorate intensively.
[0025]
In the above embodiment, two types of the coil conductors 1 are used, that is, a wide type and a narrow type. However, three or more types may be combined in order to achieve uniform heating of the object 5 to be heated. Even in this case, the combination is made so that the central portion becomes wider.
[0026]
【The invention's effect】
As described above in detail with the embodiments, according to the present invention, uniformity of heating of the object to be heated can be achieved. At this time, the cooling of the specific portion of the induction heating coil does not become insufficient, and the entire portion is cooled uniformly, so that the phenomenon of thermal deterioration of the specific portion does not occur, and a gap due to volume shrinkage or the like is generated. Therefore, the coil vibration can be reduced, and at the same time, the life can be extended.
[0027]
In particular, since the insulating member can be thinned and the insulating member can be cooled with the cooling water of the coil conductor, the heat effect from the object to be heated is removed, the mechanical strength and the insulating property are high, and the insulating member is held for a long time. obtain.
[0028]
Since the temperature sensor is inserted at the boundary between the wide and the narrow, it is possible to maintain good heat uniformity, and it is also possible to prevent the cylindrical piece from falling off by the ceramic sleeve.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.
FIG. 2 is a perspective view showing the coil conductor of FIG. 1 together with an insulating material.
FIG. 3 is a longitudinal sectional view showing an induction heating coil according to the related art.
4 is a characteristic diagram showing a longitudinal temperature distribution of an object to be heated by heating an induction heating coil shown in FIG. 3;
FIG. 5 is a longitudinal sectional view showing another induction heating coil according to the related art.
FIG. 6 is a characteristic diagram showing a longitudinal temperature distribution of an object to be heated by heating the induction heating coil shown in FIG. 5;
[Explanation of symbols]
11 (between the coil conductors 1) the coil conductor 11a hollow section 12 insulating member 13 cylindrical 14 outer peripheral insulating member 15 ceramic sleeve 16 temperature sensor _w 1, _{w 2} (coil conductors 1) width _{g 3} Interval

Claims (3)

In an induction heating coil configured by winding a coil conductor having an insulating material wound around the outer periphery thereof in the axial direction of a cylindrical heat-resistant insulating material,
The coil conductor has a hollow portion serving as a water passage hole for flowing cooling water,
Combine a plurality of types of coil conductors with different widths so that the winding density at the center is low, and the winding density on both the left and right sides with respect to the center in the axial direction is equal, An induction heating coil characterized in that the intervals between coil conductors are the same. The induction heating coil according to claim 1, wherein a temperature sensor is embedded in a portion where the width of the coil conductor changes. The induction heating coil according to claim 1 or 2, wherein the heat-resistant insulating material is formed by inserting a cylindrical ceramic sleeve into the inner periphery of a cylindrical member of castable cement.

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