JP7689379B2 - Heating coil for high frequency heating device - Google Patents

Description

The present invention relates to a heating coil used in a high-frequency heating device for heating a workpiece by using electromagnetic induction caused by a high-frequency current.

To increase the hardness of the surface of a metal workpiece, the surface of the workpiece is heated to a temperature equal to or higher than the transformation point of the metal (austenite transformation point) and then rapidly cooled (a process known as quenching). A widely used method for quenching is to use a high-frequency heating device to bring a metal ring-shaped member (heating coil) through which a high-frequency current flows close to the surface of the workpiece, and to heat the workpiece with heat generated by electromagnetic induction (Patent Document 1).

JP 2020-115428 A

However, when a workpiece is hardened using a metal, annular heating coil as in Patent Document 1, if the workpiece has an outwardly convex, angular part, only that part will be overheated, causing the grain size of that part to increase and resulting in a decrease in mechanical strength such as impact resistance. In addition, since conventional heating coils such as those in Patent Document 1 must be formed by bonding multiple parts with silver solder or the like, they are prone to breakage and leakage of cooling medium if used continuously under high output conditions (processing conditions in which a high-voltage high-frequency power source is applied). Furthermore, since conventional heating coils such as those in Patent Document 1 must be formed by soldering multiple parts, it is difficult to reproducibly manufacture coils with the same characteristics during manufacturing, which causes variations in the quality of the heated workpiece.

The object of the present invention is to provide a heating coil for a high-frequency heating device that solves the problems of the conventional heating coils for high-frequency heating treatment described above, effectively prevents the workpiece from being overheated even when it has an outwardly convex angular part, prevents the mechanical strength of the workpiece from being reduced, is less likely to break even when the output of the high-frequency power source is increased, and can be easily and inexpensively manufactured to have the same characteristics with good reproducibility during manufacturing.

Among the present inventions, the invention described in claim 1 is a heating coil used in a high-frequency heating device for heating a workpiece by utilizing electromagnetic induction by high-frequency current, the heating coil having a pair of plate-shaped grounding portions for contacting an electrode through which high-frequency current is passed, a pair of plate-shaped support portions arranged perpendicular to each of the grounding portions, and a circumferential heating portion arranged to connect the tips of the support portions, the heating portion having a shape in which an upper peripheral body and a lower peripheral body are arranged side by side above and below with their central axes aligned and a predetermined gap between them, the upper peripheral body being provided with a cooling medium flow down passage for allowing water to flow down, and the lower peripheral body being provided with a gas flow down passage for allowing gas to flow down, the gas flow down passage having a plurality of gas injection holes for injecting gas onto the workpiece and arranged so as to be inclined at a predetermined angle with respect to the central axis of the lower peripheral body .

The invention described in claim 2 is the invention described in claim 1, characterized in that the gas flow down passage is formed in a double-tube shape within a cooling medium flow down passage formed in the lower peripheral body .

The invention described in claim 3 is a manufacturing method for a heating coil for a high-frequency heating device described in claim 1, characterized in that the heating coil for the high-frequency heating device is integrally formed using a molding method in which powder of a conductive material is repeatedly laid, melted, solidified, and stacked based on three-dimensional data (hereinafter referred to as a partial deposition stacking method of a conductive material powder layer), or a molding method in which molten conductive material is stacked based on three-dimensional data (hereinafter referred to as a melt extrusion stacking method of a conductive material) .

The heating coil for a high-frequency heating device described in claim 1 (hereinafter simply referred to as the heating coil) has a gas injection hole formed in the heating section for injecting gas into the workpiece, so that by injecting gas (such as nitrogen) from the gas injection tube and injecting the gas into the workpiece from the gas injection hole, it is possible to rapidly cool a specific part of the workpiece (for example, an outwardly convex angular part) and avoid excessive heating. Therefore, according to the heating coil described in claim 1, it is possible to effectively prevent a situation in which the crystal grain size of a specific part of the workpiece becomes large and mechanical strength such as impact resistance decreases.

In addition, the heating coil manufactured by the manufacturing method described in claim 3 is formed by a method of partial welding and laminating a conductive powder layer based on three-dimensional data or a method of melt extrusion lamination of a conductive material, so that even though the circumferential heating part has a complex shape with gas injection holes, it can be manufactured cheaply and very easily, and products having the same shape and the same characteristics can be efficiently manufactured with good reproducibility regardless of the skill of the manufacturing worker. Furthermore, since the heating coil manufactured by the manufacturing method described in claim 3 is formed by a method of partial welding and laminating a conductive powder layer based on three-dimensional data or a method of melt extrusion lamination of a conductive material, there is no adhesive part by silver brazing as in the conventional heating coil, so it does not deform even if the temperature rises due to continuous use, and it can be subjected to heating treatment (quenching treatment) according to the standard for a long period of time.

The heating coil described in claim 2 has a gas downflow passage for guiding gas to the gas injection hole, which is formed in a double-tube shape inside the cooling medium downflow passage formed in the heating section. Therefore, the gas in the gas downflow passage can be kept at a low temperature by the cooling medium in the cooling medium downflow passage when it is injected onto the workpiece, so that a specific part of the workpiece can be cooled more efficiently.

If the heating coil is configured so that the gas injected from the gas injection holes is blown toward the convex ridges of the workpiece, it is possible to very effectively cool the convex angular parts of the workpiece, thereby extremely effectively preventing the crystal grain size in a particular part of the workpiece from becoming large, thereby reducing its mechanical strength.

FIG. FIG. FIG. FIG. FIG. 3 is a vertical cross-sectional view of the heating coil (cross-sectional view taken along line AA in FIG. 2). 3 is a vertical cross-sectional view of the heating coil (cross-sectional view taken along line BB in FIG. 2). 3 is a vertical cross-sectional view of the grounding portion of the heating coil (cross-sectional view taken along line CC in FIG. 2 ). 3A and 3B are vertical cross-sectional views of a heating portion of a heating coil (a is a cross-sectional view taken along line DD in FIG. 2, and b is an enlarged view of part E in a). FIG. 6 is a horizontal cross-sectional view of the heating part (cross-sectional view taken along line FF in FIG. 5). 1A and 1B are explanatory views showing a process for manufacturing a heating coil (a is a plan view, and b is a vertical cross-sectional view). FIG. 4 is an explanatory diagram (vertical cross-sectional view of the heating unit) showing a state in which a heating coil is used.

The heating coil according to the present invention must be integrally formed by a modeling method based on three-dimensional data using a three-dimensional printer. Such a modeling method can be a modeling method in which powder made of a conductive material is repeatedly laid, melted, solidified, and layered based on three-dimensional data (a method for partially fusing and laminating a conductive material powder layer), or a modeling method in which a molten conductive material is layered based on three-dimensional data (a method for melt extrusion lamination of a conductive material). Note that using a method for partially fusing and laminating a conductive material powder layer as a modeling method for a heating coil is preferable because it makes it possible to easily manufacture a heating coil having a complex shape and structure.

The conductive material used as the raw material for shaping in this invention refers to a material that is substantially non-magnetic and has good electrical conductivity. Examples of such conductive materials include copper, brass, and silver. Among these conductive materials, the use of copper is preferable because it allows for a reduction in material costs, etc., and makes it possible to inexpensively and easily manufacture heating coils using a three-dimensional printer. In addition, copper has extremely good electrical conductivity and is highly efficient at generating heat through electromagnetic induction.

In addition, when copper is used as the conductive material, it is possible to use pure copper, but it is preferable to use an alloy (high copper alloy) in which copper contains iron, tin, nickel, titanium, beryllium, zirconium, chromium, silicon, etc. in a smaller proportion than copper, because this increases the absorption of the laser and promotes the rise in temperature. Furthermore, among these copper alloys, it is more preferable to use a copper-chromium alloy in which copper contains chromium, because this effectively increases the strength of the heating coil while maintaining high manufacturing efficiency using a three-dimensional printer, and it is particularly preferable to use an alloy in which copper contains chromium and zirconium in a specified proportion (for example, an alloy containing 98.71 to 99.45 mass% copper, 0.50 to 1.00 mass% chromium, and 0.05 to 0.25 mass% zirconium (high copper alloy), etc.).

When forming the heating coil of the present invention using the method for partially fusing and laminating conductive powder layers, it is necessary to melt the laid raw material (i.e., powder made of conductive material) by irradiating it with a laser or electron beam. As the laser, a semiconductor laser, a carbon dioxide gas laser, an excimer laser, a YAG laser, a fiber laser, etc. can be suitably used, but the use of a fiber laser (i.e., a laser using an optical fiber doped with a rare earth element such as Yb as a laser medium) is preferable because it is possible to obtain laser light with high output and no deviation in the optical axis using a small device, and it is possible to very efficiently manufacture heating coils with high dimensional accuracy.

In addition, when forming a heating coil using the partial deposition lamination method of conductive material powder layers, the output and wavelength of the fiber laser are not particularly limited, but it is preferable to adjust the output to within the range of 400 to 1,000 W and the wavelength to within the range of 1,000 to 1,100 nm, as this allows for efficient forming in a short time. In addition, when copper (pure copper) is used as the conductive material, it is also possible to add an absorbent made of a mixed powder of graphite and inorganic oxide to the copper powder in order to improve the laser absorptivity of the copper powder and increase the manufacturing efficiency of the heating coil.

The heating coil according to the present invention must have a pair of plate-shaped grounding parts for contacting the electrodes through which high-frequency current is passed, a pair of plate-shaped support parts arranged perpendicular to each of the grounding parts, and a circumferential heating part provided to connect the tips of the support parts. The shape of each support part is not particularly limited as long as it is a pair of plate-shaped (or rod-shaped) parts arranged perpendicular to each of the grounding parts, but it is preferable that the corners are chamfered to prevent discharge phenomena from occurring when power is applied.

On the other hand, the heating section needs to be formed in a continuous circumferential shape, but is not limited to a circular shape, and may be a non-circular shape (for example, a rectangular ring shape in plan view), a shape that forms part of a ring (i.e., an arc shape), a shape that forms part of a rectangular or polygonal ring, etc. In addition, it may have a shape in which multiple circular bodies arranged above and below, non-circular bodies (such as a rectangular ring shape in plan view), arc bodies, and bodies that form part of a rectangular or polygonal ring are connected by one or more vertical pillars, etc.

The heating coil according to the present invention requires that the circumferential heating portion has gas injection holes formed therein for injecting gas at the workpiece. The gas to be injected from the gas injection holes at the workpiece can be air, nitrogen gas, a mist of quenching coolant, or the like. In this way, by forming gas injection holes in the circumferential heating portion and injecting cooling gas from the gas injection holes at the workpiece, it is possible to rapidly cool a specific portion of the workpiece (for example, an outwardly convex angular portion) and avoid excessive heating.

It is also preferable that the circumferential heating section is provided with a cooling medium flow passage for cooling the workpiece after heating and for cooling the heating section itself. Furthermore, the cooling medium flow passage can be provided with multiple injection holes for injecting the cooling medium onto the workpiece after heating. By providing such injection holes, it is possible to further improve the cooling efficiency of the workpiece after heating.

In addition, the heating coil according to the present invention is preferably provided with a series of cooling medium flow-down paths for flowing the cooling medium down inside each support part, or inside each ground part and each support part, so as to connect with the cooling medium flow-down path inside the heating part. The cooling medium flow-down path may be a single one provided to connect the left and right ground parts, the left and right support parts, and the inside of the heating part, or two cooling medium flow-down paths provided on the left and right sides of the heating coil to connect the ground parts, the support parts, and the inside of the heating part, respectively. In addition, if the cooling medium flow-down path has no seams or steps of a predetermined height or more (1.0 mm or more) on the inner wall, or the bent parts and connecting parts are formed in a gentle curve (curved with a radius of curvature of 5 mm or more), the cooling medium will flow down very smoothly, and the cooling efficiency of the heating parts, ground parts, and supports of the heating coil will be extremely good, which is preferable.

As described above, the heating coil according to the present invention has gas injection holes formed in the circumferential heating portion, and although the shape of the circumferential heating portion is complex, it can be manufactured very easily because it is formed by a method of partial deposition lamination of conductive powder layers based on three-dimensional data or a method of melt extrusion lamination of conductive materials.

Below, one embodiment of the heating coil according to the present invention will be described in detail with reference to the drawings.

[Example 1]
<Heating coil structure>
1 to 10 show the heating coil of Example 1, and the heating coil 1 is composed of a coil body 5 integrally formed from a copper alloy (high copper alloy), an insulating plate (not shown) formed in a sheet shape from a synthetic resin (fluororesin) having insulating properties and heat resistance, and a screw member (not shown). The heating coil 1 has a size of length (front to back) x width (width) x height = 300 mm x 150 mm x 100 mm (the length of the maximum part of the length, width, and height).

The coil body 5 is formed by a modeling method using a three-dimensional printer, which will be described later, and has grounding parts 2a, 2b for contacting the electrodes of a high-frequency power source, a circumferential heating part 4 for heating the workpiece (workpiece) by induction heating, and support parts 3a, 3b for supporting the heating part 4 at a position away from the grounding parts 2a, 2b. The heating part 4 is divided into an upper circumferential body 15 and a lower circumferential body 16. The left support part 3a supports the upper circumferential body 15, and the right support part 3b supports the lower circumferential body 16. Since the coil body 5 is formed by a modeling method using a three-dimensional printer, the entire body is the same color, and the entire surface has the same roughness (surface roughness).

Each grounding portion 2a, 2b is formed as a pair of flat rectangular parallelepipeds (plates) on the left and right, and is arranged so that one side faces the other and is adjacent to the left and right at a predetermined distance (about 2 mm). Also, as shown in FIG. 8, inside each grounding portion 2a on the left side, a cooling medium flow path 10a for flowing down a cooling medium (water, etc.) is formed, and the tip side portion is divided into two parts to form an upper flow path 10α and a lower flow path 10β. Similarly, inside the grounding portion 2b on the right side, a cooling medium flow path 10b for flowing down a cooling medium is formed, and the tip side portion is divided into two parts to form an upper flow path 10γ and a lower flow path 10δ. In addition, cylindrical exhaust pipes 7a and 7b are provided on the upper surface of each grounding portion 2a and 2b, respectively, so as to protrude upward, and are connected to the cooling medium flow path 10a and the cooling medium flow path 10b, respectively.

The left support part 3a is formed in a flat rectangular parallelepiped shape at the base end, and the tip end is formed in a flat rectangular parallelepiped shape with a narrower vertical width than the base end. The left support part 3a connects the left ground part 2a and the upper circumferential body 15 of the heating part 4. Inside the left support part 3a, an upper cooling medium flow passage 11 with a vertically elongated elliptical cross section for allowing the cooling medium to flow down, and a lower cooling medium flow passage 12 with a vertically elongated elliptical cross section narrower than the upper cooling medium flow passage 11 are provided in parallel vertically. The base ends of the upper cooling medium flow passage 11 and the lower cooling medium flow passage 12 are connected to the upper flow passage 10α and the lower flow passage 10β of the ground plate 2a, respectively.

On the other hand, the right support part 3b has a base end formed in a flat rectangular parallelepiped shape with the same vertical width as the left support part 3a, and a tip end formed in a flat rectangular parallelepiped shape with the same vertical width as the lower circumferential body 16 of the heating part 4. The right ground part 2b and the lower circumferential body 16 of the heating part 4 are connected to each other. Inside the right support part 3a, an upper cooling medium flow passage 13 with a vertically elongated elliptical cross section for flowing the cooling medium down, and a lower cooling medium flow passage 14 with a narrower vertically elongated elliptical cross section than the upper cooling medium flow passage 13 are provided in parallel above and below. The base ends of the upper cooling medium flow passage 13 and the lower cooling medium flow passage 14 are connected to the upper flow passage 10γ and the lower flow passage 10δ of the ground plate 2b, respectively.

The left and right support parts 3a, 3b are arranged next to each other on the left and right with one plate surface facing each other and a specified distance (approximately 2 mm) between them. The base edge of each support part 3a, 3b is connected to the inner edge of the left and right grounding parts 2a, 2b, and the plate surface of each support part 3a, 3b is perpendicular to the plate surface of each grounding part 2a, 2b.

<Heating section structure>
On the other hand, the heating section 4 is for heating the workpiece inserted (close to the workpiece), and has an upper circumferential body 15 and a lower circumferential body 16 having the same outer diameter arranged vertically with their central axes aligned. The upper circumferential body 15 is formed in a thick cylindrical shape (a cylindrical shape separated into left and right at the base end), and its inside functions as a cooling medium flow-down passage 17 for allowing the cooling medium to flow downward. A protrusion 18 of a predetermined vertical width is provided around the inner circumference of the upper circumferential body 15 so as to protrude inward.

The upper peripheral body 15 is divided into a left and right portion at the base end, with the left portion connected to the tip of the support portion 3a. The separated right portion is connected to a pipe support 19 formed in a rectangular parallelepiped shape with a constant vertical width. The plate surface of the pipe support 19 is parallel to the support portion 3a (i.e., flush with the support portion 3b). In addition, a cooling medium flow path 20 is formed inside the pipe support 19 so as to communicate with the cooling medium flow path 17. Furthermore, the pipe support 19 has an injection pipe 9b arranged perpendicular to the plate surface, and is in communication with the cooling medium flow path 20.

The lower circumferential body 16 is formed in a flat, thick cylindrical shape, and its inside functions as a cooling medium flow path 21 for flowing down the cooling medium. The inside of the cooling medium flow path 21 is formed with a gas flow path 22 for flowing down the gas (nitrogen, etc.) for cooling the workpiece. That is, the inside of the lower circumferential body 16 has a double-tube structure, and the inside of the gas flow path 22 is independent from the inside of the cooling medium flow path 21. The gas flow path 22 has inner and outer side walls 23a, 23b inclined at a predetermined angle (about 45°) with respect to the central axis of the lower circumferential body 16, and has a parallelogram cross section. The upper plate (top plate) of the cooling medium flow path 21 also serves as the upper plate of the gas flow path 22. Furthermore, three gas injection pipes 24, 24... are radially provided on the lower circumferential body 16 for injecting gas from the outside into the gas flow path 22. Each gas injection pipe 24, 24... protrudes outward from the front, left and right sides at the bottom end of the outer periphery of the lower circumferential body 16.

Twelve gas injection holes 25, 25... for injecting gas to the workpiece are drilled at equal intervals on the same circumference in the upper plate of the cooling medium flow down passage 21 (i.e., the upper surface of the lower circumferential body 16) (see FIG. 10). The gas injection holes 25, 25... are drilled cylindrically so as to be inclined at a predetermined angle (about 45°) with respect to the central axis of the lower circumferential body 16 (see FIG. 9). The gas injection holes 25, 25... are arranged radially with respect to the central axis of the lower circumferential body 16. The lengths from the central axis C of the gas injection holes 25, 25... to the inner and outer side walls 23a, 23b of the gas flow down passage 22 are equal.

Furthermore, the lower circumferential body 16 is divided into a left and right part at the base end side, and the right part is connected to the tip of the support part 3b. The separated left part is connected to a pipe support 26 formed in a rectangular parallelepiped shape with the same vertical width as the lower circumferential body 16. The plate surface of the pipe support 26 is parallel to the support part 3b (i.e., it is flush with the support part 3a). In addition, a cooling medium flow-down passage 27 is formed inside the pipe support 26 so as to communicate with the cooling medium flow-down passage 21. Furthermore, an injection pipe 9a is provided in the pipe support 26 so as to be perpendicular to the plate surface, and is in a state of communication with the cooling medium flow-down passage 27.

<Cooling medium flow path structure>
In the above-mentioned heating coil 1, two series of cooling medium flow paths 6a, 6b for cooling the coil itself and the workpiece are formed inside the heating part 4, the left and right ground parts 2a, 2b, and the support parts 3a, 3b. That is, one cooling medium flow path 6a runs from the right injection pipe 9b to the discharge pipe 7a via the cooling medium flow path 20 inside the right piping support 19, the cooling medium flow path 17 inside the upper peripheral body 15, the upper cooling medium flow path 11 inside the left support part 3a, and the cooling medium flow path 10a inside the left ground part 2a. On the other hand, the other cooling medium flow path 6b extends from the left injection pipe 9a, via the cooling medium flow path 27 inside the left piping support 26, the cooling medium flow path 21 inside the lower peripheral body 16, the lower cooling medium flow path 14 inside the right support part 3b, and the cooling medium flow path 10b inside the right grounding part 2b, to the discharge pipe 7b.

In addition, because the heating coil 1 is integrally formed by a three-dimensional printer, all bends and connecting parts of both cooling medium flow paths 6a, 6b are formed in gentle curves (curves with a radius of curvature of 5 mm or more), and no sharp bends are formed. In addition, both cooling medium flow paths 6a, 6b have no seams or steps of a specified height or more (1.0 mm) formed on the inner walls.

Furthermore, a sheet-like insulating plate (not shown) of a predetermined thickness (approximately 2.0 mm) is sandwiched between the left and right grounding parts 2a, 2b, between the left and right support parts 3a, 3b, and between the left and right base end parts of the heating part 4, and in this state, the left and right support parts 3a, 3b and the insulating plate 31 are screwed together with bolts (not shown) inserted through the screw holes 8, 8. Note that these bolts are in a state in which the support parts 3a, 3b and the insulating plate 31 are screwed together via bushes (not shown) made of synthetic resin (glass epoxy resin) that has insulating and heat-resistant properties, so that the support parts 3a, 3b are not electrically connected to each other via the bolts.

<Method of manufacturing the heating coil>
11 shows how the coil body 5 of the heating coil 1 is formed, and the three-dimensional printer device M for forming the heating coil 1 has a frame F with a rectangular parallelepiped recessed portion formed in the center, a lifting member provided so as to be able to rise and fall relative to the frame F, an irradiation means S for irradiating the laser L, a reflection means R for reflecting the laser, a driving means (not shown) for raising and lowering the lifting member, etc. The lifting member is provided with a table T having approximately the same area as the opening of the recessed portion of the frame F.

When manufacturing the heating coil 1 using the three-dimensional printer device M, first, copper alloy (high copper alloy) powder is laid to a predetermined thickness (for example, 30 μm) on the surface of the table T of the lifting member in the raised position (the copper powder is laid to cover only the gap between the surface of the table T and the surface of the outer frame of the frame F). Then, a laser (fiber laser) L of a predetermined output is irradiated onto the copper alloy powder in a predetermined shape to melt part of the copper alloy powder, which is then cooled and solidified to form part of the heating coil 1.

As described above, after forming a portion of the heating coil 1, the table T of the lifting member is lowered by a predetermined height (e.g., 30 μm) by the driving means. Then, at that height position, the following operations are repeated: "laying copper alloy powder on the upper side of the previously formed portion of the heating coil 1 → irradiating the copper alloy powder with the laser L → cooling and solidifying the molten copper alloy (solidification by solidification)." Then, as described above, the operations of "lowering the table T of the lifting member → laying copper alloy powder → irradiating the copper alloy powder with the laser L → cooling and solidifying the molten copper alloy" are repeated a predetermined number of times (e.g., 5,000 times) to integrally form the heating coil 1 made of copper alloy.

<Function of heating coil>
The heating coil 1 constructed as described above has the left and right grounding portions 2a, 2b grounded to the electrodes, and a workpiece W (for example, a workpiece having a shape in which a small-diameter cylindrical portion protrudes concentrically downward from the underside of a large-diameter cylindrical portion) inserted inside the circumferential heating portion 4 as shown in FIG. 12. In this state, an external power source (high-frequency power source) is turned on via the electrodes, and the workpiece W can be heated (hardened) by utilizing the electromagnetic induction phenomenon.

In addition, the cooling medium is injected from the left and right injection pipes 9a, 9b into the cooling medium flow paths 6a, 6b, passes through the inside of the heating portion 4 (i.e., the upper circumferential body 15 and the lower circumferential body 16), passes through the support portions 3a, 3b and the grounding portions 2a, 2b, and is discharged from the discharge pipes 7a, 7b. This efficiently cools the heating portion 4, the support portions 3a, 3b, and the support portions 3a, 3b, and accurately prevents damage caused by melting the insulating plate (not shown).

When hardening the workpiece W in this way, gas (such as nitrogen) is injected from the gas injection pipes 24, 24... and the gas is sprayed onto the workpiece W from the gas injection holes 25, 25..., thereby rapidly cooling a specific portion of the workpiece W (for example, the outwardly convex angular portion, the α portion in FIG. 12) and preventing excessive heating. The gas injected from the gas injection pipes 24, 24... is sprayed from the gas injection holes 25, 25... via the gas flow passage 22 provided circumferentially inside the upper circumferential body 15 of the heating section 4. This means that the pressure of the gas sprayed from the gas injection holes 25, 25... varies little, and the specific portion of the workpiece W can be cooled evenly.

<Effect of heating coil>
As described above, the heating coil 1 has the gas injection holes 25, 25... formed in the heating section 4 for injecting gas toward the workpiece W, so that a specific portion of the workpiece W (the outwardly convex angular portion α in FIG. 12) can be rapidly cooled to avoid excessive heating by injecting gas (such as nitrogen) introduced from outside through the gas injection holes 25, 25... toward the workpiece W. Therefore, the heating coil 1 can effectively prevent a situation in which the crystal grain size of a specific portion of the workpiece W becomes large, resulting in a decrease in mechanical strength such as impact resistance.

In addition, since the heating coil 1 is formed by a modeling method using a three-dimensional printer device M (i.e., a method of partially fusing and laminating conductive powder layers based on three-dimensional data), it can be manufactured very easily despite the complex shape of the circumferential heating portion 4, and products with the same shape and characteristics can be manufactured efficiently with good reproducibility regardless of the skill of the manufacturing worker. Furthermore, since the heating coil 1 is formed by a modeling method using a three-dimensional printer device M, there are no adhesive parts using silver solder as in conventional heating coils, so it does not deform even if the temperature rises due to continuous use, and heating treatment (hardening treatment) can be performed according to the standard for a long period of time.

Furthermore, the heating coil 1 is provided with a cooling medium downflow passage 17 and a cooling medium downflow passage 21 in the heating section 4 for causing the cooling medium to flow down, and a gas downflow passage 22 for directing the gas to the gas injection holes 25, 25, etc., and the gas downflow passage 22 is formed in a double tube shape within the cooling medium downflow passage 21. Therefore, the gas in the gas downflow passage 22 can be injected onto the workpiece W while being kept at a low temperature by the cooling medium in the cooling medium downflow passage 21, and a specific portion of the workpiece W (the α portion in FIG. 12) can be cooled more efficiently.

In addition, the heating coil 1 is configured so that the gas injected from the gas injection holes 25, 25... is blown toward the convex ridge of the workpiece W (i.e., the axis is inclined at a predetermined angle), so that the outwardly convex angular portion of the workpiece W (the α portion in FIG. 12) can be cooled very effectively, and it is possible to extremely effectively prevent the crystal grain size of the outwardly convex portion of the workpiece W from becoming large, thereby reducing its mechanical strength.

<Example of changing the heating coil>
The heating coil according to the present invention is not limited to the above-described embodiment, and the materials, shapes, structures, and other configurations of the grounding portion, support portion, heating portion, injection pipe, exhaust pipe, gas injection hole, gas flow path, cooling medium flow path, etc. can be appropriately changed as necessary without departing from the spirit of the present invention.

For example, the heating section of the heating coil is not limited to an upper peripheral body and a lower peripheral body arranged side by side with a predetermined gap between them as in the above embodiment, but can be changed to a simple ring shape, a rectangular peripheral body in a plan view, or a divided ring body or peripheral body arranged horizontally above and below and connected by a vertical columnar body (a columnar body extending in the vertical direction).

Furthermore, the heating section is not limited to having multiple cooling medium downflow paths in the heating section as in the above embodiment, but may have a single cooling medium downflow path in the heating section. When multiple cooling medium downflow paths are provided in the heating section as in the above embodiment, it becomes possible to more efficiently cool the workpiece after heating and cool the heating section itself. Furthermore, the heating section is not limited to having the gas downflow path formed in a double tube shape in the cooling medium downflow path as in the above embodiment, but may have the gas downflow path formed separately from the cooling medium downflow path.

In addition, the heating coil according to the present invention is not limited to the above embodiment in which the pair of grounding parts and the pair of supporting parts are insulated by an insulating plate made of fluororesin (PTFE, PFA, FEP, ETFE, PCTFE, ECTFE, PVDF), but can also be modified to have the pair of grounding parts and the pair of supporting parts insulated by an insulating plate made of other synthetic resins having insulating and heat-resistant properties, such as polyacetal (POM), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), etc.

In addition, the overall shape and size of the heating coil according to the present invention, the shape of the heating part (overall shape, number and angle of the gas injection holes facing the workpiece, etc.), the shape and size of the grounding part, the shape and size of the support part, the type (material) and thickness of the sheet-like insulating plate, the number of bolts for clamping the insulating plate, etc. are not limited to the above-mentioned embodiment and can be changed as appropriate depending on the shape of the workpiece to be hardened.

The heating coil of the present invention has the excellent effects described above, and can therefore be suitably used as a component for heating a workpiece using electromagnetic induction.

1...Heating coil 2a, 2b...Grounding part 3a, 3b...Supporting part 4...Heating part 6a, 6b...Cooling medium flow path 7a, 7b...Discharge pipe 9a, 9b...Injection pipe 10a, 10b...Cooling medium flow path 11...Upper cooling medium flow path 12...Lower cooling medium flow path 13...Upper cooling medium flow path 14..Lower cooling medium flow path 15..Upper circumferential body 16..Lower side circumferential body 17..Cooling medium flow path 21..Cooling medium flow path 22..Gas flow path 24a, 24b..Gas injection pipe 25..Gas injection hole

Claims (3)

A heating coil for use in a high-frequency heating device for heating a workpiece by utilizing electromagnetic induction caused by a high-frequency current,
A pair of plate-shaped grounding portions to be attached to an electrode through which a high-frequency current is passed;
A pair of plate-shaped support parts arranged perpendicular to each of the grounding parts;
and a circumferential heating portion provided so as to connect the tips of the support portions,
The heating unit has a shape in which an upper peripheral body and a lower peripheral body are arranged vertically with a predetermined gap therebetween and aligned along their central axes,
The upper peripheral body is provided with a cooling medium flow-down passage for allowing water to flow down, and the lower peripheral body is provided with a gas flow-down passage for allowing gas to flow down,
A heating coil for a high-frequency heating device, characterized in that a plurality of gas injection holes for injecting gas onto a workpiece are provided in the gas flow path so as to be inclined at a predetermined angle with respect to the central axis of the lower peripheral body . 2. The heating coil for a high frequency heating device according to claim 1, wherein the gas flow passage is formed in a double tube shape within a cooling medium flow passage formed in the lower peripheral body . A method for manufacturing a heating coil for a high-frequency heating device according to claim 1,
A manufacturing method for a heating coil for a high-frequency heating device, characterized in that the heating coil for the high-frequency heating device is integrally formed using a molding method in which powder of an electrically conductive material is repeatedly laid, melted, solidified, and layered based on three-dimensional data, or a molding method in which molten electrically conductive material is layered based on three-dimensional data.

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