JP7714225B2 - Induction heating coil and high frequency hardening device - Google Patents

Description

This disclosure relates to an induction heating coil and induction hardening device with improved power efficiency.

Induction hardening equipment hardens workpieces to increase their strength. When the heat capacity of a workpiece is large, induction hardening equipment requires a large amount of power.
FIG. 7A is a perspective view that schematically shows the overall structure of the induction hardening device 1 of Patent Document 1.
As shown in FIG. 7( a ), the induction hardening device 1 includes an induction heating coil 10 and a high-frequency oscillator 20 .
The induction heating coil 10 has a first lead portion 3, a second lead portion 4, a coil portion 2, a first power supply lead portion 7, a second power supply lead portion 8, a coolant supply port 5, and a coolant discharge port 6.
The high frequency oscillator 20 receives power (AC power of 100V or 200V, 50 or 60 Hz, etc.) from a commercial power source 52 and converts the power into power with a frequency and amplitude suitable for hardening.

FIG. 9 is a circuit diagram that schematically shows the induction hardening device 1.
As shown in FIG. 9, the high-frequency oscillator 20 includes a high-frequency oscillator 53 , a transformer 54 , and a connecting line 21 .
High frequency power is supplied to the coil portion 2 from the high frequency oscillator 20 side.
The high frequency oscillator 53 is connected to the commercial power supply 52 and generates power of an arbitrary frequency. The high frequency oscillator 53 generates power of a high frequency, but may also generate power of a low frequency.
The primary side of the transformer 54 is connected to the high-frequency oscillator 53 .
In addition, the secondary side of the transformer 54 is connected to the first power supply lead portion 7 and the second power supply lead portion 8 via a connection wire 21, and supplies power of any amplitude to the first power supply lead portion 7 and the second power supply lead portion 8.
In other words, the high-frequency oscillator 20 is connected to the first power supply lead 7 and the second power supply lead 8 via the connection wire 21, and supplies power of any frequency and any amplitude to the first power supply lead 7 and the second power supply lead 8.

As shown in FIG. 7(a), the first power lead 7 and the second power lead 8 are connected to the first lead 3 and the second lead 4, respectively.
The first lead portion 3 and the second lead portion 4 face each other and extend linearly across an insulator 9. The insulator 9 electrically insulates the first lead portion 3 from the second lead portion 4, and is made of an inorganic material, an organic material, air, or the like.

The coil portion 2 is disposed between the first lead portion 3 and the second lead portion 4 and is electrically connected to the first lead portion 3 and the second lead portion 4 .
As shown in Figure 7(a), the coil section 2 is a coil for induction heating a workpiece (not shown) placed inside the coil section 2, and is made of a good conductor such as copper or a copper alloy. The cross section of the coil section 2 has a rectangular hollow structure. A coolant (water, air, etc.) passes through the inside of the coil section 2 to suppress temperature rise during induction heating.

The first lead portion 3 and the second lead portion 4 are hollow and linear. A coolant (water, air, etc.) passes through the interior of the first lead portion 3 and the second lead portion 4, which are made of hollow linear members, to suppress the temperature rise during induction heating. Specifically, the coolant is supplied into the interior of the first lead portion 3 from the coolant supply port 5, passes through the interior of the coil portion 2, is supplied into the interior of the second lead portion 4, and is discharged from the coolant discharge port 6.

Japanese Patent Application Laid-Open No. 2019-87508

FIG. 7B is a cross-sectional view that schematically shows a cross section perpendicular to the longitudinal direction of the first lead portion 3 and the second lead portion 4 of Patent Document 1.
As shown in Figure 7(b), the cross section perpendicular to the longitudinal direction of the first lead portion 3 and the second lead portion 4 has a rectangular hollow structure. The first lead portion 3 and the second lead portion 4 are hollow rectangular pipes, which are easy to manufacture. In particular, a square cross section is preferable from the viewpoint of ease of manufacture.
The first lead portion 3 and the second lead portion 4 are arranged close to each other and parallel to each other. An insulator 9, which may be an inorganic material, an organic material, or air, is arranged between the first lead portion 3 and the second lead portion 4. In the case of Figure 7(b), the insulator 9 is air.

The two-dot chain lines on the left side of Fig. 7(b) are center lines between the outer ring and inner ring of each side of the cross section of the first lead portion 3. In other words, the two-dot chain lines on the left side of Fig. 7(b) are lines that schematically represent each side of the cross section of the first lead portion 3, without regard to the width of each side of the cross section of the first lead portion 3. The two-dot chain lines of the first lead portion 3 form a square, which is made up of four sides.
In FIG. 7(b), the upper right vertex of the square of the first lead portion 3 is designated as Q1, and the intersections of the other sides are designated as Q2, Q3, and Q4 clockwise, with the four sides being defined as side Q1Q2, side Q2Q3, side Q3Q4, and side Q4Q1.
Similarly, the two-dot chain line of the second lead portion 4 on the right side of FIG. 7B forms a square, which is made up of four sides.
The upper left vertex of the second lead portion 4 is designated as Q5, and the intersections of the other sides are designated as Q6, Q7, and Q8 in a counterclockwise direction, with the four sides being defined as side Q5Q6, side Q6Q7, side Q7Q8, and side Q8Q5.
The side Q4Q1 and the side Q2Q3 are parallel to each other.
The sides Q1Q2 and Q4Q1 are perpendicular to each other. Therefore, the length of the side Q1Q2 is the shortest distance between the side Q4Q1 and the side Q2Q3.
The side Q8Q5 and the side Q6Q7 are parallel to each other.
Side Q5Q6 and side Q8Q5 are perpendicular to each other. Therefore, the length of side Q5Q6 is the shortest distance between side Q8Q5 and side Q6Q7.
The sides Q1Q2 and Q5Q6 are parallel to each other and face each other closely with an insulator 9 interposed therebetween.
7(b), the right side Q1Q2 of the first lead portion 3 and the left side Q5Q6 of the second lead portion 4 are closely opposed to each other. The direction of the current flowing through the first lead portion 3 and the direction of the current flowing through the second lead portion 4 are opposite to each other.
As a result, the higher the frequency of the power supplied to the first lead portion 3 and the second lead portion 4, and the greater the power, the higher the current density becomes at the surface where the first lead portion 3 and the second lead portion 4 face each other, as shown by the hatched area in Figure 7(b), due to the proximity effect. Heat is generated at the surface where the first lead portion 3 and the second lead portion 4 face each other, and the power efficiency at the first lead portion 3 and the second lead portion 4 cannot be improved, leaving room for improvement.
The present disclosure provides an induction heating coil that improves power efficiency in the first lead portion 3 and the second lead portion 4 and saves power.

FIG. 8(a) is a perspective view that schematically shows the overall structure of another induction hardening device 1 of the prior art.
8A is the same as FIG. 7A except that the first lead portion 3, the second lead portion 4 and the coil portion 2 are cylindrical pipes.
Cylindrical pipes are easy and inexpensive to manufacture.
FIG. 8B is a cross-sectional view that schematically shows a cross section perpendicular to the longitudinal direction of the first lead portion 3 and the second lead portion 4 in FIG. 8A.
The two-dot chain line on the left side of Figure 8(b) is the center line between the outer ring and inner ring of the cross section of the first lead portion 3. In other words, the two-dot chain line of the first lead portion 3 is a line that schematically represents the cross section of the first lead portion 3, eliminating the concept of the width of the cross section of the first lead portion 3. The two-dot chain line of the first lead portion 3 forms a circular shape. The two-dot chain line of the second lead portion 4 is the same as the two-dot chain line of the first lead portion 3.
In Figure 8 (b), the upper vertex of the two-dot chain circle of the first lead portion 3 is defined as D1, the lower vertex of the circle is defined as D2, the upper vertex of the two-dot chain circle of the second lead portion 4 is defined as D4, and the lower vertex of the circle is defined as D5.

8(b), the arc-shaped right side D1D2 of the first lead portion 3 and the arc-shaped left side D4D5 of the second lead portion 4 are close to each other and face each other. The direction of the current flowing through the first lead portion 3 and the direction of the current flowing through the second lead portion 4 are opposite to each other.
As a result, the higher the frequency of the power supplied to the first lead portion 3 and the second lead portion 4, and the greater the power, the higher the current density becomes at the surface where the first lead portion 3 and the second lead portion 4 face each other, as shown by the hatched area in Figure 8(b), due to the proximity effect. Heat is generated at the surface where the first lead portion 3 and the second lead portion 4 face each other, and the power efficiency at the first lead portion 3 and the second lead portion 4 cannot be improved, leaving room for improvement.
The present disclosure provides an induction heating coil that improves power efficiency in the first lead portion 3 and the second lead portion 4 and saves power.

An induction heating coil according to one aspect of the present disclosure includes:
In an induction heating coil having a coil section that is placed close to a workpiece to excite an induction current in the workpiece, and a lead section that supplies current to the coil section,
The lead portion has a first lead portion and a second lead portion that face each other with an insulator interposed therebetween,
two opposing surfaces of the first lead portion and the second lead portion are curved or inclined surfaces,
The two opposing surfaces are parallel.
According to the above aspect, the area of the surface where the first lead portion 3 and the second lead portion 4 face each other can be increased by making the surface curved or inclined, thereby providing an induction heating coil with improved power efficiency.

In a preferred embodiment, the curved surface has a wave shape.
According to the above aspect, the area of the surface where the first lead portion 3 and the second lead portion 4 face each other is increased by making the surface area of the wave-shaped portion, thereby providing an induction heating coil with improved power efficiency.
In a more preferred embodiment, the inclined surface has a wave shape.
According to the above aspect, the area of the surface where the first lead portion 3 and the second lead portion 4 face each other can be increased by making the area of the inclined surface a wave-shaped area, thereby providing an induction heating coil with improved power efficiency.
In a more preferred embodiment, the combined structure of the curved surface and the inclined surface is a wave-shaped structure.
According to the above aspect, the area of the surface where the first lead portion 3 and the second lead portion 4 face each other is increased by making the surface area of the wave-shaped portion, thereby providing an induction heating coil with improved power efficiency.
In a more preferred embodiment, an induction hardening apparatus can be provided that includes the induction heating coil described above and a high-frequency oscillator.
According to the above embodiment, the area of the surface where the first lead portion 3 and the second lead portion 4 face each other is increased, thereby improving the power efficiency in the lead portion and providing a power-saving induction hardening device.
Another induction heating coil according to one aspect of the present disclosure has a coil section that is placed close to a workpiece to excite an induced current in the workpiece, and a lead section that supplies current to the coil, wherein the lead section has a first lead section and a second lead section that face each other via an insulator, and the two opposing surfaces of the first lead section and the second lead section have arc-shaped cross sections perpendicular to the longitudinal direction of the two opposing surfaces, and portions of the arc-shaped opposing surfaces are parallel.
According to the above aspect, by making the arc shapes of the opposing surfaces partially parallel, power efficiency can be improved in the lead portion, and a power-saving induction heating coil can be provided.
A preferred embodiment is an induction hardening device having the induction heating coil described above and a high-frequency oscillator.
According to the above aspect, by making the arc shapes of the opposing surfaces parallel to one another, it is possible to improve power efficiency in the lead portion and provide a power-saving induction hardening device.

According to one aspect of the present disclosure, the area of the surface where the first lead portion and the second lead portion face each other can be increased, improving the power efficiency of the first lead portion and the second lead portion and providing an energy-saving induction heating coil.

1 is a perspective view schematically illustrating a lead portion according to a first embodiment of the present disclosure. FIG. 1 is a cross-sectional view schematically illustrating a cross section of a lead portion in a first embodiment according to one aspect of the present disclosure. FIG. 10 is a cross-sectional view schematically illustrating a cross section of a lead portion in a second embodiment of the present disclosure. FIG. 10 is a cross-sectional view schematically illustrating a cross section of a lead portion in embodiment 3 which is one aspect of the present disclosure. FIG. 10 is a cross-sectional view schematically illustrating a cross section of a lead portion in embodiment 4, which is one aspect of the present disclosure. FIG. 10 is a cross-sectional view schematically illustrating a cross section of a lead portion in embodiment 5, which is one aspect of the present disclosure. 1A and 1B are diagrams of an induction hardening device according to one embodiment of the prior art, in which FIG. 1A is a perspective view that schematically shows the overall structure, and FIG. 1B is a cross-sectional view that schematically shows the cross section of a lead portion. 1A and 1B are diagrams of another embodiment of a conventional induction hardening device, in which (a) is a perspective view that schematically shows the overall structure, and (b) is a cross-sectional view that schematically shows a cross section of a lead portion. FIG. 1 is a schematic circuit diagram of a conventional induction hardening device.

More specific embodiments of the present disclosure will be described below. However, more detailed descriptions than necessary may be omitted. For example, detailed descriptions of already well-known matters or redundant descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the inventors provide the accompanying drawings and the following description to enable those skilled in the art to fully understand the present disclosure, and do not intend for them to limit the subject matter described in the claims. In the following description, the same or similar components will be designated by the same reference numerals.

(Embodiment 1)
Hereinafter, the first lead portion 3 and the second lead portion 4 of the induction hardening device 1 according to the first embodiment of the present disclosure will be described with reference to the drawings.
The overall schematic configuration of the induction hardening apparatus 1 of the first embodiment is substantially the same as that of the conventional induction hardening apparatus 1 shown in FIGS. 7, 8 and 9, and therefore a description of the overall schematic configuration of the induction hardening apparatus 1 of the first embodiment will be omitted.
In embodiment 1, the cross-sectional shapes perpendicular to the longitudinal direction of the first lead portion 3 and the second lead portion 4 of embodiment 1 are different from the cross-sectional shapes perpendicular to the longitudinal direction of the first lead portion 3 and the second lead portion 4 of the prior art.

1 is a perspective view schematically illustrating the first lead portion 3 and the second lead portion 4 in the first embodiment. The first lead portion 3 and the second lead portion 4 are hollow and extend linearly. A coolant passes through the inside of the first lead portion 3 and the second lead portion 4, and the first lead portion 3 and the second lead portion 4 are cooled by the coolant.
Between the first lead portion 3 and the second lead portion 4, an insulator 9 such as an inorganic material, an organic material, or air is interposed.
1, the coil 2 (not shown) is connected to the front side of the first lead 3 and the second lead 4. The first power supply lead 7 and the second power supply lead 8 (not shown) are electrically connected to the rear side of the first lead 3 and the second lead 4, respectively.

FIG. 2 is a cross-sectional view that schematically shows the cross section of the first lead portion 3 and the second lead portion 4 in the first embodiment.
The two surfaces of the first lead portion 3 and the second lead portion 4 facing each other are configured as a curved surface and an inclined surface.
The two-dot chain line in FIG. 2 is the center line between the outer ring and the inner ring in cross section.
The present disclosure will be described in detail with reference to FIG.
In FIG. 2, the top right vertex of the first lead portion 3 is defined as P1, and the other inflection points are defined clockwise as P1', P1'', P2, P3, and P4. The top left vertex of the second lead portion 4 is defined as P5, and the other inflection points are defined counterclockwise as P5', P5'', P6, P7, and P8.

The two opposing sides of the first lead portion 3 and the second lead portion 4 are composed of side P1P1', side P1'P1'', and side P1''P2 in the first lead portion 3, and side P5P5', side P5'P5'', and side P5''P6 in the second lead portion 4.
Side P1P1' is a curved arc that is convex to the left, sides P1'P1'' are straight lines, and sides P1''P2 are curved arcs that are convex to the right.
Side P5P5' is a curved arc that convexly faces left, sides P5'P5'' are straight, and sides P5''P5'' are curved arcs that convexly face right.
The left side P1P1'P1''P2 and the right side P5P5'P5''P6 are parallel to each other. An insulator 9 is disposed between the left side P1P1'P1''P2 and the right side P5P5'P5''P6.
Sides P4P1 and P2P3 are parallel, and sides P8P5 and P6P7 are parallel. Sides P3P4 and P7P8 are curved.

In FIG. 2, the length of the line segment Q1Q2 that passes through P4 and is perpendicular to the side P4P1 is the same as the length of the side Q1Q2 in FIG. 7 of the prior art.
The length of the left side P1P1'P1''P2 is longer than the length of the line segment Q1Q2 because it is made up of a combination of curved and straight lines.
In FIG. 2, the length of the line segment Q5Q6 that passes through P8 and is perpendicular to the side P8P5 is the same as the length of the side Q5Q6 in FIG. 7 of the prior art.
The length of the right side P5P5'P5''P6 is longer than the length of the line segment Q5Q6 because it is made up of a combination of curved and straight lines.

The two opposing surfaces of the first lead portion 3 and the second lead portion 4 are configured as a combination of curved and inclined surfaces, so the surface area of the two opposing surfaces can be made larger than the surface area of the two opposing surfaces of the prior art shown in Figure 7. As a result, the current density on the two opposing surfaces can be reduced, resulting in power-saving first lead portion 3 and second lead portion 4.

The shape of the combination of the curved and inclined surfaces described above can be produced using metal 3D additive manufacturing (AM) techniques, such as powder bed, deposition, and binder jetting, which can produce complex three-dimensional metal shapes.
The term "curved surface" as used above includes the meaning that two opposing surfaces are partially curved, and also includes the combination of a curved surface and an inclined surface, and the combination of a curved surface and a vertical surface (flat surface).
The shapes of the left side P1P1'P1''P2 and the right side P5P5'P5''P6 may be reversed left to right.
The curve P1P1'P1"P2 on the left cross section and the curve P5P5'P5"P6 on the right cross section are parallel, and the curve P5P5'P5"P6 is a parallel curve to the curve P1P1'P1"P2. A parallel curve is a curve that is a certain distance away in a direction perpendicular to the tangent at each point.
"The two opposing surfaces of the first lead portion and the second lead portion are curved or inclined surfaces, and the two opposing surfaces are parallel" means that "the two opposing sides of the cross section perpendicular to the longitudinal direction of the first lead portion and the second lead portion are parallel curved lines or inclined parallel lines."
Hereinafter, when curves are said to be parallel, it means that the curves are parallel.

(Embodiment 2)

Hereinafter, the first lead portion 3 and the second lead portion 4 showing another embodiment of the present disclosure will be described with reference to FIG.
The cross sections of the first lead portion 3 and the second lead portion 4 in Fig. 2 of the first embodiment are different in shape from the cross sections of the first lead portion 3 and the second lead portion 4 in Fig. 3 of the second embodiment. The surfaces facing the first lead portion 3 and the second lead portion 4 in Fig. 3 are all curved.

FIG. 3 is a diagram showing a schematic cross section of the first lead portion 3 and the second lead portion 4, with the center line representing the cross section.
The first lead portion 3 and the second lead portion 4 are each made up of four sides.
3, the top right vertex of the first lead 3 is designated P1, the intersections of the other sides are designated P2, P3, and P4 in a clockwise direction, and the four sides are defined as side P1P2, side P2P3, side P3P4, and side P4P1. The top left vertex of the second lead 4 is designated P5, the intersections of the other sides are designated P6, P7, and P8 in a counterclockwise direction, and the four sides are defined as side P5P6, side P6P7, side P7P8, and side P8P5.

The curve P1P2 on the left side of Figure 3 and the curve P5P6 on the right side are wavy shapes that combine convex and concave portions. Convex portions are areas that protrude outward from the squares P1P2P3P4 and P5P6P7P8, and concave portions are areas that inward from the squares P1P2P3P4 and P5P6P7P8.

The curve P1P2 and the curve P5P6 are parallel to each other.
An insulator 9 is disposed between the curve P1P2 and the curve P5P6.
Sides P2P3 and P4P1 are parallel to each other, and sides P6P7 and P8P5 are parallel to each other.
Sides P3P4 and sides P7P8 are straight lines, but may be curved lines.

In FIG. 3, the length of the line segment Q1Q2 (two-dot chain line) representing the distance between the side P4P1 and the side P2P3 is the same as the length of the side Q1Q2 in FIG. 7 of the prior art.
The length of the curved line P1P2 on the left side is longer than the length of the line segment Q1Q2 because it is a curved line.
The length of the line segment Q5Q6 (two-dot chain line) representing the distance between the side P8P5 and the side P5P6 is the same as the length of the side Q5Q6 in FIG. 8 of the prior art.
Similarly to the above, the length of the curve P5P6 on the right side is longer than the length of the line segment Q5Q6 (two-dot chain line) that represents the distance between the side P8P5 and the side P6P7.

Since the two opposing surfaces of the first lead portion 3 and the second lead portion 4 are configured as curved surfaces, the surface area of the two opposing surfaces can be made larger than the surface area of the two opposing surfaces of the conventional art shown in Fig. 7. As a result, the current density on the two opposing surfaces can be reduced, and power-saving first lead portion 3 and second lead portion 4 can be realized.
The shape of the curve P1P2 on the left side and the shape of the curve P5P6 on the right side may be reversed left to right.

(Embodiment 3)

Hereinafter, the first lead portion 3 and the second lead portion 4 showing another embodiment of the present disclosure will be described with reference to FIG.
The cross sections of the first lead portion 3 and the second lead portion 4 in FIG. 2 of the first embodiment and the cross sections of the first lead portion 3 and the second lead portion 4 in FIG. 4 of the third embodiment have different shapes.
Specifically, the surfaces where the first lead portion 3 and the second lead portion 4 face each other in FIG. 2 are curved and inclined, whereas the surfaces where the first lead portion 3 and the second lead portion 4 face each other in FIG. 4 are all inclined.

FIG. 4 is a diagram showing a schematic cross section of the first lead portion 3 and the second lead portion 4, with the center line representing the cross section.
The side P1P2 is not perpendicular to the side P4P1, but is an inclined straight line with an acute angle at the angle P4P1P2.
The side P5P6 is not perpendicular to the side P8P5, but is an inclined straight line with an obtuse angle at the angle P8P5P6.
The sides P1P2 and P5P6 are parallel to each other.
An insulator 9 is disposed between the side P1P2 and the side P5P6.
The side P4P1 and the side P2P3 are parallel to each other, and the side P8P5 and the side P6P7 are parallel to each other.
Sides P3P4 and sides P7P8 are straight lines, but may be curved lines.

In FIG. 4, the length of the line segment Q1Q2 (two-dot chain line) representing the distance between the side P4P1 and the side P2P3 is the same as the length of the side Q1Q2 in FIG. 7 of the prior art.
The length of the left side P1P2 is longer than the length of the line segment Q1Q2 because it is an inclined straight line.
Similarly, the length of the right side P5P6 is longer than the length of the line segment Q5Q6 (two-dot chain line).
Therefore, since the two opposing surfaces of the first lead portion 3 and the second lead portion 4 are configured as inclined surfaces, the surface area of the two opposing surfaces can be made larger than the surface area of the two opposing surfaces of the conventional technology shown in Figure 7, so the current density on the two opposing surfaces can be reduced, and power-saving first lead portion 3 and second lead portion 4 can be realized.
The shapes of the left side P1P2 and the right side P5P6 may be reversed left to right.

(Embodiment 4)

Hereinafter, the first lead portion 3 and the second lead portion 4 showing another embodiment of the present disclosure will be described with reference to FIG.
The cross sections of the first lead portion 3 and the second lead portion 4 in FIG. 2 of the first embodiment and the cross sections of the first lead portion 3 and the second lead portion 4 in FIG. 5 of the fourth embodiment have different shapes.
Specifically, the surfaces where the first lead portion 3 and the second lead portion 4 face each other in FIG. 2 are curved and inclined, whereas the surfaces where the first lead portion 3 and the second lead portion 4 face each other in FIG. 5 are curved with the inclined surface as the axis.

FIG. 5 is a diagram showing a schematic cross section of the first lead portion 3 and the second lead portion 4, with the cross section being represented by the center line.
Side P1P2 (dashed line) is not perpendicular to side P4P1, but is an inclined straight line with angle P4P1P2 being an acute angle.
Side P5P6 (dashed line) is not perpendicular to side P8P5, but is an inclined straight line with angle P8P5P6 being an obtuse angle.
The curve P1P2 is a waveform formed by combining convex portions and concave portions, tilted around the side P1P2 (broken line) as an axis.
The curve P5P6 is a wave-shaped curve that combines convex portions and concave portions, tilted around the side P5P6 (broken line) as an axis.

The curves P1P2 and P5P6 are parallel to each other.
An insulator 9 is disposed between the curve P1P2 and the curve P5P6.
The side P4P1 and the side P2P3 are parallel to each other, and the side P8P5 and the side P6P7 are parallel to each other.
Sides P3P4 and sides P7P8 are straight lines, but may be curved lines.

In FIG. 5, the length of the line segment Q1Q2 (two-dot chain line) representing the distance between the side P4P1 and the side P2P3 is the same as the length of the side Q1Q2 in FIG. 7 of the prior art.
The length of the curve P1P2 on the left side is longer than the length of the line segment Q1Q2 because it is an inclined curve.
In FIG. 5, the length of the line segment Q5Q6 (two-dot chain line) representing the distance between the side P8P5 and the side P5P6 is the same as the length of the side Q5Q6 in FIG. 7 of the prior art.
The length of the curve P5P6 on the right side is also longer than the length of the line segment Q5Q6, just like the left side.

Since the two opposing surfaces of the first lead portion 3 and the second lead portion 4 are configured as inclined surfaces, the surface area of the two opposing surfaces can be made larger than the surface area of the two opposing surfaces of the conventional technology shown in Fig. 7. As a result, the current density on the two opposing surfaces can be reduced, and power-saving first lead portion 3 and second lead portion 4 can be realized.
The shapes of the left side P1P2 and the right side P5P6 may be reversed left to right.

(Embodiment 5)

Hereinafter, the first lead portion 3 and the second lead portion 4 showing another embodiment of the present disclosure will be described with reference to FIG.
The cross sections of the first lead portion 3 and the second lead portion 4 in FIG. 2 of the first embodiment and the cross sections of the first lead portion 3 and the second lead portion 4 in FIG. 5 of the fourth embodiment have different shapes.
Specifically, the surfaces where the first lead portion 3 and the second lead portion 4 face each other in FIG. 2 are curved and inclined, whereas the surfaces where the first lead portion 3 and the second lead portion 4 face each other in FIG. 6 are substantially cylindrical.

FIG. 6 is a diagram showing a schematic cross section of the first lead portion 3 and the second lead portion 4, with the center line representing the cross section.
The cross section of the first lead portion 3 is a circle surrounded by the right side C1C2 and the left side C2C1, and has a protrusion C3 on the right side C1C2.
The cross section of the second lead portion 4 is a circle surrounded by the left side C4C5 and the right side C5C4, and has a recess C6 on the left side C4C5.
The convex portion C3 and the concave portion C6 are parallel to each other.
An insulator 9 is disposed between the right side C1C3C2 and the left side C4C6C5.

In FIG. 6, the side C1C3C2 of the cross section of the first lead portion 3 is longer than the length of the semicircle D1D2 on the left side of FIG. 8(b).
Similarly, the length of the left side C4C6C5 of the cross section of the second lead portion 4 is longer than the length of the semicircle D4D5 on the right side in FIG. 8(b).

Since the two opposing cross sections of the first lead portion 3 and the second lead portion 4 are configured to be longer than the length of the semicircle, the length can be made longer than the two opposing semicircles shown in the prior art in Fig. 8. As a result, the current density on the two opposing surfaces of the first lead portion 3 and the second lead portion 4 can be reduced, and power-saving first lead portions 3 and second lead portions 4 can be realized.
The shapes of the left side C1C3C2 and the right side C4C6C5 may be reversed left to right.

In FIG. 2, the two opposing surfaces of the first lead portion 3 and the second lead portion 4 are a combination of a curved surface and an inclined surface, but they may also be a combination of a curved surface and a vertical surface (flat surface).
Although the curves P1P2 on the left side and the curves P5P6 on the right side in FIG. 3 are wavy shapes that combine convex portions and concave portions, they may be curves that simply have one convex portion or one concave portion.

The inventions according to embodiments 1 to 4 can be interchanged or combined as long as no contradictions arise.

REFERENCE SIGNS LIST 1 High-frequency hardening device 2 Coil portion 3 First lead portion 4 Second lead portion 7 First power supply lead portion 8 Second power supply lead portion 9 Insulator 10 Induction heating coil 20 High-frequency oscillator

Claims (10)

An induction heating coil having a coil section that is placed close to a workpiece to excite an induced current in the workpiece, and a lead section that supplies current to the coil section,
The lead portion has a first lead portion and a second lead portion that face each other with an insulator interposed therebetween,
two opposing surfaces of the first lead portion and the second lead portion are curved or inclined surfaces,
An induction heating coil characterized in that the two opposing surfaces are parallel. The induction heating coil of claim 1, characterized in that the curved surface is wavy. The induction heating coil of claim 1, characterized in that the inclined surface is wavy. The induction heating coil of claim 1, characterized in that the two opposing surfaces have a combined structure of a curved surface and an inclined surface. The induction heating coil described in claim 4, characterized in that the combined structure of the curved surface and the inclined surface is a wave-shaped structure. An induction heating coil as described in any one of claims 1 to 5, characterized in that the first lead portion and the second lead portion are manufactured using metal 3D additive manufacturing technology. An induction hardening device comprising the induction heating coil according to any one of claims 1 to 6 and a high-frequency oscillator. An induction heating coil having a coil section that is placed close to a workpiece to excite an induced current in the workpiece and a lead section that supplies current to the coil,
The lead portion has a first lead portion and a second lead portion that face each other with an insulator interposed therebetween,
a cross section perpendicular to a longitudinal direction of the two opposing surfaces of the first lead portion and the second lead portion has an arc shape;
An induction heating coil, characterized in that the arc shapes of the opposing surfaces are partially parallel to each other. The induction heating coil of claim 8, wherein the first lead portion and the second lead portion are manufactured using metal 3D additive manufacturing technology. An induction hardening device comprising the induction heating coil according to claim 8 or 9 and a high-frequency oscillator.