Heating coil for high-frequency heating device

Abstract

[Problem] To provide a heating coil capable of efficiently quenching a workpiece in a short time, and controlling the depth of a cured layer produced by quenching the workpiece for each height position in accordance with the shape of the workpiece. [Solution] This heating coil (1) comprises: ground parts (2a, 2b) for attaching to an electrode; a pair of support parts (3a, 3b) which are respectively orthogonal to the ground parts (2a, 2b) and are arranged so as to face each other in parallel with each other, and in which distal-end portions are vertically branched; a circumferential upper heating part (4α) which is provided so as to connect the upper-side distal ends of the support parts (3a, 3b); and a circumferential lower heating part (4β) which is provided so as to connect the lower-side distal ends of the support parts (3a, 3b) to each other. A heat release part (R) is formed so as to protrude outward in an upper-side branch portion of the left support part (3a), and a high-frequency current from the ground parts (2a, 2b) is supplied to the upper heating part (4α) via the heat release part (R). [Selected Drawing] Figure 1

Description

Heating coil for high frequency heating equipment

[0001] The present invention relates to a heating coil used in a high-frequency heating device for heating a workpiece by utilizing electromagnetic induction caused by a high-frequency current.

[0002] In order to increase the hardness of the surface of a metal workpiece (workpiece), the surface of the workpiece is heated to a temperature equal to or higher than the metal's transformation point (austenite transformation point) and then rapidly cooled (a process known as quenching). A widely used method for performing such quenching is to heat the workpiece by bringing a metal member (heating coil) through which a high-frequency current flows into close proximity to the surface of the workpiece using a high-frequency heating device. A known heating coil for use in such quenching is one disclosed in Patent Document 1, which has an annular coil made of a metal pipe fitted around the workpiece and connected to a conductive plate (copper plate) for supplying high-frequency power.

[0003] Japanese Patent Application Laid-Open No. 2020-115428

[0004] However, in the heating coils for the conventional high-frequency heating devices described above, current always flows in one direction inside the annular coil. Therefore, if a large amount of current flows inside the coil, the workpiece is overheated, the crystal grains of the hardened structure of the workpiece become coarse, and the toughness of the workpiece decreases, resulting in a decrease in mechanical strength. Conversely, if only a small amount of current flows inside the coil, the hardened layer depth of the workpiece becomes shallow, resulting in insufficient hardening. Therefore, with the heating coils for conventional high-frequency heating devices, it is difficult to control the depth of the hardened layer caused by hardening the workpiece.

[0005] The object of the present invention is to provide a practical heating coil that solves the problems of the heating coils for conventional high-frequency heating devices described above, that can efficiently harden a workpiece in a short time, that can effectively prevent the workpiece from being overheated due to its shape, that can prevent a decrease in the mechanical strength of the workpiece, and that can easily control the depth of the hardened layer formed by hardening the workpiece.

[0006] The invention described in claim 1 of the present invention is a heating coil used in a high-frequency heating device for heating a workpiece by utilizing electromagnetic induction caused by high-frequency current, and is characterized in that it has a pair of plate-shaped grounding portions for contacting electrodes through which high-frequency current is passed, a pair of support portions each perpendicular to the grounding portions and arranged parallel to each other, with the tip portions branching into multiple parts, and a series of multiple circumferential heating portions arranged to connect the tips of each branch portion of the pair of support portions, and a U-shaped heat dissipation portion (bypass current path forming portion) formed so as to protrude outward in one of the branch portions formed on one side of the pair of support portions.

[0007] The invention described in claim 2 is characterized in that, in the invention described in claim 1, the heat dissipation part is provided with a current path length adjustment means for adjusting the length of the flow path of the current flowing inside.

[0008] The invention described in claim 3 is characterized in that, in the invention described in claim 1, the current path length adjustment means comprises two protruding pieces formed to protrude outward from the main body of the support part, and a connecting member that can connect those protruding pieces at different positions in the protruding direction.

[0009] The heating coil for a high-frequency heating device according to the present invention can be integrally formed using a molding method that repeatedly lays, melts, solidifies, and layers conductive powder based on three-dimensional data (hereinafter referred to as a partial deposition method for conductive powder layers), or a molding method that layers molten conductive material based on three-dimensional data (hereinafter referred to as a conductive material melt extrusion deposition method). By using the partial deposition method for conductive powder layers or the conductive material melt extrusion deposition method, the heating coil for a high-frequency heating device according to the present invention can be manufactured inexpensively and very easily. Furthermore, heating coils (products) for high-frequency heating devices with the same shape and characteristics can be manufactured efficiently and with good reproducibility, regardless of the skill of the manufacturing worker. Furthermore, because the heating coil for a high-frequency heating device manufactured by the partial deposition method for conductive powder layers or the conductive material melt extrusion deposition method does not have any silver brazing adhesives like conventional heating coils, it does not deform even when the temperature rises during continuous use, and can be subjected to standard heating treatments (hardening treatments) for a long period of time.

[0010] The conductive material used as a raw material for shaping in the above-mentioned partial deposition method of conductive material powder layers and melt extrusion deposition method of conductive material refers to a material that is substantially non-magnetic and has good conductivity. Examples of such conductive materials include copper, brass, and silver. Among these conductive materials, copper is preferred because it reduces material costs, enables inexpensive and easy manufacturing of heating coils using a three-dimensional printer, and provides excellent conductivity and high heat generation efficiency through electromagnetic induction. Furthermore, while pure copper can be used as the conductive material, it is preferable to use an alloy (high-copper alloy) containing copper and iron, tin, nickel, titanium, beryllium, zirconium, chromium, silicon, etc. in smaller proportions than copper, as this increases laser absorption and promotes temperature rise.

[0011] Furthermore, when forming the heating coil according to the present invention using the method for partially fusing and laminating conductive material powder layers, it is necessary to melt the laid raw material for the formation (i.e., the powder made of the conductive material) by irradiating it with a laser or an electron beam. As the laser, a semiconductor laser, a carbon dioxide laser, an excimer laser, a YAG laser, a fiber laser, etc. can be suitably used. However, 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 enables a high-output laser beam with a stable optical axis using a small device, and enables the efficient production of heating coils with high dimensional accuracy.

[0012] The heating coil for the high-frequency heating device described in claim 1 (hereinafter simply referred to as the heating coil) has a heat dissipation section formed in the flow path that supplies current to the upper heating section or the flow path that supplies current to the lower heating section, so that the heat generation amount of the heating section on the side where the heat dissipation section is formed (the upper heating section or the lower heating section) can be made smaller than that of the heating section on the side where the heat dissipation section is not formed (the lower heating section or the upper heating section), and therefore the depth of the hardened layer caused by quenching the workpiece can be easily controlled for each height position to match the shape of the workpiece.

[0013] The heating coil according to claim 2 is provided with a current path length adjustment means for adjusting the length of the current flowing inside the heat dissipation portion R. By changing the length of the current flowing inside the heat dissipation portion, the amount of magnetic flux generated in the heat dissipation portion can be changed, and the amount of heat generated in the upper heating portion to which current is supplied via the heat dissipation portion can be changed. Therefore, with the heating coil according to claim 2, it is very easy to control the depth of the hardened layer caused by quenching for each height position of the workpiece.

[0014] The heating coil described in claim 3 has a current path length adjustment means consisting of two protruding pieces formed to protrude outward from the main body of the support part, and a connecting member that can connect these protruding pieces at different positions in the protruding direction.By simply changing the connecting position of the two protruding pieces, the length of the current flow path flowing inside the heat dissipation part can be changed, and the amount of heat generated in the heat dissipation part can be changed.Since the amount of heat generated in the upper heating part or the lower heating part can be changed, it is extremely easy to control the depth of the hardened layer caused by hardening for each height position of the workpiece.

[0015] 5A is a perspective view of a heating coil (coil body); FIG. 5B is a perspective view of a heating coil (coil body); FIG. 5C is a front view of a heating coil (coil body); FIG. 5D is a rear view of a heating coil (coil body); FIG. 5E is a plan view of a heating coil (coil body); FIG. 5F is a left side view (partially see-through left side view) of a heating coil (coil body); FIG. 5G is a right side view (partially see-through right side view) of a heating coil (coil body); FIG. 5H is a cross-sectional view of a heating coil (coil body) (a is a cross-sectional view taken along line A-A in FIG. 5, b is a cross-sectional view taken along line B-B in FIG. 5, c is a cross-sectional view taken along line C-C in FIG. 5, d is a cross-sectional view taken along line D-D in FIG. 5, and e is a cross-sectional view taken along line E-E in FIG. 5); FIG. 5H is an explanatory diagram (plan view) showing how to use a heating coil (coil body); FIG. 5H is a vertical cross-sectional view); FIG. 5I is an explanatory diagram (left side view) showing a modified example of a heat release unit.

[0016] 1 to 8 show a heating coil, and the heating coil 1 is composed of a metal coil body C, an insulating plate (not shown) formed in a sheet shape from a synthetic resin (such as a fluororesin) having insulating properties and heat resistance, screw members such as bolts and nuts (not shown), a metal connecting member 13, and fixing members (screw members) for fixing the connecting member 13 to the coil body C.

[0017] The coil body C is integrally formed using a three-dimensional printer by a molding method (i.e., a method of partially fusing and laminating conductive material powder layers) that involves repeatedly laying, melting, solidifying, and laminating powder made of a conductive material (copper alloy (high copper alloy)) based on three-dimensional data, and has dimensions of length (front to back) × width (width) × height = 300 mm × 150 mm × 100 mm (the lengths of the maximum portions of length, width, and height). The coil body C also has grounding portions 2a and 2b for contacting the electrodes of a high-frequency power source, a heating portion 4 (i.e., a series of circumferential upper and lower heating portions 4α and 4β) for heating the workpiece (workpiece) by induction heating, and support portions 3a and 3b for supporting the upper and lower heating portions 4α and 4β at positions spaced from the grounding portions 2a and 2b.

[0018] Each grounding portion 2a, 2b is formed as a pair of flat rectangular parallelepipeds (plates) and is arranged adjacent to the left and right with their inner sides facing each other and a predetermined distance (approximately 2.0 mm) between them. Left and right support portions 3a, 3b are connected to the inner edges of each grounding portion 2a, 2b, respectively, with the plate surfaces of the support portions 3a, 3b perpendicular to the plate surfaces of the grounding portions 2a, 2b. Each grounding portion 2a, 2b has a hollow coolant flow path 5a, 5b for allowing a cooling medium to flow downward. Inlet ports 25, 24 provided at the upper ends of each grounding portion 2a, 2b are connected to the coolant flow path 5a, 5b (see FIGS. 6, 7, and 8a).

[0019] The right support portion 3b is formed in a plate shape with a constant thickness, and the base end portion (base end portion 3b ｂ On the other hand, the upper branch portion 3b is formed in a band shape with a constant width. ｄ１ and the lower branch portion 3b ｄ２ The upper branch portion 3b is bifurcated into two parts. ｄ１ The right support portion 3b has two hollow cooling medium flow paths 6b for allowing the cooling medium to flow downward. １ , 6b ２ The upper coolant flow passage 6b １The tip end portion of the upper branch portion 3a ｄ１ through the inside of the upper branch part 3a ｄ１ and the lower coolant flow passage 6b ２ The distal end portion of the lower branch portion 3b ｄ２ through the inside of the lower branch part 3b ｄ２ The cooling medium flow path 6b inside the support portion 3b １ , 6b ２ are connected to the coolant flow field 5b inside the grounding portion 2b (see FIGS. 6 and 8B).

[0020] On the other hand, the left support portion 3a also has a base end portion (base end portion 3a ｂ ) and the shape of the portion on the front side is the same as the right support portion 3b. That is, the base end portion 3a ｂ The part on the first application side is an upper branch part 3a ｄ１ and the lower branch portion 3a ｄ２ The upper branch portion 3a is bifurcated. ｄ１ However, the upper part of the left support part 3a is inclined downwards toward the front. ｂ and the upper branch portion 3a ｄ１ are not continuously connected (separated), but are connected via a heat dissipation portion (a bypass current path forming portion) R formed so as to protrude laterally.

[0021] In addition, the base end 3a of the left support portion 3a ｂ The inside of the cooling medium passage 6a is provided with two hollow cooling medium passages 6a for allowing the cooling medium to flow downward. １ , 6a ２ The upper coolant flow passage 6a １ The distal end portion of the base end portion 3a ｂ The lower coolant flow passage 6a ２ The distal end portion of the lower branch portion 3a ｄ２ through the inside of the lower branch part 3a ｄ２ The cooling medium flow path 6a inside the support portion 3a １ , 6a ２The base ends of the upper branch portions 3a are connected to the coolant flow paths 5a inside the grounding portion 2a (see FIGS. 7 and 8(b)). ｄ１ Inside the cooling medium flow path 6a １ In addition to the above, the coolant flow path 6a ３ is formed in a hollow shape (see FIG. 7 and FIG. 8(c)).

[0022] The heat release section R is composed of a first protruding piece 11, a second protruding piece 12, a connecting member 13, and fastening members (screw members) consisting of a bolt B, a nut N, and a washer W for fastening (screwing) the connecting member 13 to the first protruding piece 11 and the second protruding piece 12. The first protruding piece 11 is formed in a wide (horizontally elongated) rectangular shape with a constant thickness. A horizontally elongated slit 15 with a constant width is formed in the center in the height and width directions. A cooling medium flow path 7 for flowing the cooling medium is formed circumferentially within the first protruding piece 11, surrounding the slit 15 (see FIG. 8(d)). Furthermore, a discharge pipe 16 for discharging the cooling medium that has flowed down the internal cooling medium flow path 7 to the outside is provided on the rear surface of the first protruding piece 11 near the tip end, protruding rearward and bending upward. Furthermore, the base end of the cooling medium flow path 7 within the first protruding piece 11 is connected to the upper cooling medium flow path 6a within the left support portion 3a. １ (See FIG. 7). The first protruding piece 11 is connected to the base end 3a of the support portion 3a. ｂ At the tip end of the base end 3a, the plate surface is oriented vertically. ｂ The plate surface is integrally formed so as to be perpendicular to the plate surface.

[0023] Similarly to the first protruding piece 11, the second protruding piece 12 is also formed in a wide (horizontally elongated) rectangular shape with a constant thickness. A horizontally elongated slit 17 with a constant width is formed in the center in the front-rear and width directions. A cooling medium flow path 8 for allowing the cooling medium to flow downward is formed in the interior of the second protruding piece 12 in a circumferential shape surrounding the slit 17 (see FIG. 8( d )). A discharge pipe 18 for discharging the cooling medium that has flowed downward through the internal cooling medium flow path 8 to the outside is provided at the tip of the upper surface of the second protruding piece 12 so as to protrude upward. Furthermore, the base end of the cooling medium flow path 8 inside the second protruding piece 12 is connected to the upper branch portion 3 a of the left support portion 3 a. ｄ１ The cooling medium flow path 6a ３ (See FIG. 7). The second protruding piece 12 is connected to the upper branch portion 3a of the support portion 3a. ｄ１ At the bottom edge of the base end of the upper branch portion 3a, the plate surface is oriented horizontally. ｄ１ The plate surface is integrally formed so as to be perpendicular to the plate surface.

[0024] On the other hand, the connecting member 13 is formed separately from the coil main body C from metal (such as iron) and has a shape obtained by bending a strip of a constant width into an L-shape (orthogonal to the longitudinal direction) in a direction perpendicular to the longitudinal direction. Furthermore, screw insertion holes (not shown) are drilled at both longitudinal ends of the connecting member 13. The connecting member 13 is fixed (screwed) across the first protruding piece 11 and the second protruding piece 12 using the screw insertion holes at both ends, the slits 15 in the first protruding piece 11, and the slits 17 in the second protruding piece 12, with fixing members (screwed members) composed of bolts B, nuts N, and washers W. The fixed connecting member 13 can be slid along the longitudinal direction (the direction in which it protrudes to the left) of the first protruding piece 11 and the second protruding piece 12 by loosening (or releasing) the screwed state of the fixing members.

[0025] The support portions 3a and 3b are arranged adjacent to each other on the left and right sides with a predetermined distance (approximately 2.0 mm) between them, with their inner surfaces facing each other. ｄ１and the upper branch 3b of the support 3b ｄ１ The upper heating section 4α is provided to connect the lower branch section 3b of the support section 3a. ｄ２ and the lower branch 3b of the support portion 3b ｄ２ An upper heating section 4β is provided to connect the above.

[0026] The upper heating section 4α and the upper heating section 4β are used to heat a workpiece inserted therein (or placed close to the workpiece). The upper heating section 4α is a series of rings (annular) with its base end separated into left and right halves, while the upper heating section 4β is a series of rings (annular) that are slightly larger (larger in diameter) than the upper heating section 4α. The inner circumferential surfaces of the upper heating section 4α and the upper heating section 4β are inclined so that the diameter gradually decreases from top to bottom. The upper heating section 4α and the upper heating section 4β are arranged concentrically above and below at a predetermined distance (so that the difference in height between the bottom surfaces is approximately 5.0 mm).

[0027] A hollow coolant flow path 9 for allowing a cooling medium to flow downward is formed inside the upper heating section 4α, and a hollow coolant flow path 10 for allowing a cooling medium to flow downward is formed inside the upper heating section 4β (see FIG. 8(e)). Furthermore, two discharge pipes 22, 23 for discharging the cooling medium from the internal coolant flow path 10 are integrally provided on the front side of the upper heating section 4β, protruding forward and bending upward. Furthermore, the coolant flow path 9 inside the upper heating section 4α is connected to the upper branch part 3b of the right support part 3b. ｄ１ The cooling medium flow path 6b １ and the upper branch 3a of the left support part 3a ｄ１ The cooling medium flow path 6a ３ On the other hand, the coolant flow path 10 inside the lower heating part 4β is connected to the tip of the lower branch part 3a of the left support part 3a. ｄ２ The cooling medium flow path 6a ２ and the lower branch 3b of the right support part 3b. ｄ２ The cooling medium flow path 6b ２ (See FIGS. 6, 7, and 8(c)).

[0028] Furthermore, although not shown, sheet-like insulating plates of a predetermined thickness (approximately 2.0 mm) are sandwiched between the left and right grounding portions 2a, 2b of the coil body C, between the left and right support portions 3a, 3b, between the left and right base end portions of the upper heating portion 4α, and between the left and right base end portions of the lower heating portion 4β, and in this state, the left and right support portions 3a, 3b and the insulating plates are fastened together with screw members (bolts and nuts, not shown) inserted through screw holes (not shown) formed through the support portions 3a, 3b. Note that these screw members fasten the support portions 3a, 3b and the insulating plates via bushings made of insulating and heat-resistant synthetic resin (glass epoxy resin), so that the support portions 3a, 3b are not electrically connected to each other via the bolts.

[0029] <Method of use and operation of heating coil> The heating coil 1 configured as described above has the left and right grounding portions 2a, 2b grounded to the electrodes, and with the workpiece inserted inside the series of circumferential heating portions 4a, 4b, an external power source (high frequency power source) is turned on via the electrodes, and the workpiece can be heated (hardened) using the electromagnetic induction phenomenon.

[0030] After the workpiece is heated, a cooling medium (water) is injected from the injection pipe 24 of the right-side grounding portion 2b, and passes through the cooling medium flow path 5b inside the grounding portion 2b to the upper cooling medium flow path 6b inside the right-side support portion 3b. １ , the cooling medium flows through the cooling medium flow path 9 inside the upper heating unit 4α, and then flows to the upper branch portion 3a of the left support unit 3a. ｄ１ The cooling medium flow path 6a ３ The cooling medium is then passed through the cooling medium flow passage 8 inside the second protruding piece 12 and then discharged from the discharge pipe 18. The cooling medium injected from the injection pipe 24 of the grounding portion 2b is passed through the cooling medium flow passage 5b inside the grounding portion 2b and then discharged from the lower cooling medium flow passage 6b inside the support portion 3b. ２ The cooling medium is then injected from the injection pipe 25 of the left grounding part 2a, passed through the cooling medium flow path 5a inside the grounding part 2a, and discharged from the discharge pipe 22. At the same time, the cooling medium is injected from the injection pipe 25 of the left grounding part 2a, passed through the cooling medium flow path 5a inside the grounding part 2a, and discharged from the upper cooling medium flow path 6a inside the left support part 3a. １The cooling medium is then passed through the cooling medium flow passage 7 inside the first protruding piece 11 and then discharged from the discharge pipe 16. The cooling medium injected from the injection pipe 25 of the grounding part 2a is passed through the cooling medium flow passage 5b inside the grounding part 2a and then discharged from the lower cooling medium flow passage 6a inside the support part 3a. ２ The cooled medium passes through the coolant flow path 10 inside the lower heating section 4β, and is then discharged from the discharge pipe 23.

[0031] As described above, by injecting the cooling medium through the injection pipes 24 and 25, allowing it to flow thoroughly inside the coil body C, and then discharging it through the discharge pipes 16 and 18 and the discharge pipes 22 and 23, damage caused by melting of the insulating plate (not shown) can be accurately prevented. Furthermore, by allowing the cooling medium to flow down into the upper heating section 4α and the lower heating section 4β in this manner, the workpiece can be rapidly cooled. Then, by rapidly cooling the workpiece after being heated in this manner, the workpiece is hardened.

[0032] Furthermore, as described above, when hardening a workpiece, when power is supplied to the grounding portions 2a, 2b, current (AC) flows through the inside and near the surface of the left and right support portions 3a, 3b, and through the inside and near the surface of the upper heating portion 4α and the lower heating portion 4β. When current flows through the inside and near the surface of the upper heating portion 4α and the lower heating portion 4β in this manner, magnetic flux is generated around the upper heating portion 4α and the lower heating portion 4β, and the workpiece is heated by electromagnetic induction.

[0033] At this time, at the lower portions of the support portions 3a and 3b, the AC current supplied from the ground portions 2a and 2b flows through the interior and surface of the support portions 3a and 3b and is guided linearly to the lower heating portion 4β over the shortest distance. Meanwhile, at the upper portions of the support portion 3a, the current applied from the ground portions 2a and 2b is guided to the upper heating portion 4α through the heat dissipation portion (detour current path forming portion) R (i.e., the first protrusion 7, the connecting member 13, and the second protrusion 8) and then through the upper heating portion 4α to the heat dissipation portion R. When the current applied from the ground portions 2a and 2b passes through the heat dissipation portion R, a magnetic flux is also generated in the heat dissipation portion R, thereby reducing the magnetic flux generated in the upper heating portion 4α. Therefore, the amount of heat generated by electromagnetic induction in the workpiece is smaller in the upper heating portion 4α than in the lower heating portion 4β. Therefore, even when a large amount of alternating current is passed through the grounding portions 2a and 2b (when a high voltage is applied), the portion of the workpiece located inside the upper heating portion 4α is not excessively heated, and it is possible to adjust the depth of the hardened layer formed by quenching to a thin value.

[0034] 9, the loop (current path length) of the heat release portion R can be changed by loosening (or releasing) the fastening members that secure the connecting member 13 to the first protruding piece 11 and the second protruding piece 12 and sliding the connecting member 13 along the longitudinal direction (the direction in which it protrudes to the left) of the first protruding piece 11 and the second protruding piece 12. Increasing the current path length of the heat release portion R (i.e., moving the fastening position of the connecting member 13 outward as shown in FIG. 9(a) ) increases the magnetic flux generated in the heat release portion R, thereby significantly reducing the amount of magnetic flux generated in the upper heating portion 4α. Therefore, the amount of heat generated by the workpiece due to electromagnetic induction in the upper heating portion 4α is significantly reduced.

[0035] On the other hand, if the loop length of the heat dissipation portion R is shortened (i.e., if the fixing position of the connecting member 13 is moved inward as shown in FIG. 9(b)), the magnetic flux generated in the heat dissipation portion R decreases, and the amount of decrease in the magnetic flux generated in the upper heating portion 4α decreases. Therefore, in the upper heating portion 4α, the amount of heat generated in the workpiece due to electromagnetic induction is smaller than in the case where there is no heat dissipation portion R, but the difference is small.

[0036] As described above, the amount of heat generated in the portion of the workpiece located inside the upper heating portion 4α can be easily adjusted by adjusting the loop length of the heat dissipation portion R. That is, the first protruding piece 11 having the slit 15 formed therein, the second protruding piece 12 having the slit 17 formed therein, and the connecting member 13 that can be fixed (screwed) at different positions using the slits 15 and 17 function as a current path length adjusting means for adjusting the length of the path of the AC current flowing inside the coil body C.

[0037] <Effects of the heating coil> As described above, the heating coil 1 has a pair of plate-shaped grounding portions 2a, 2b for contacting electrodes through which high-frequency current is passed, a pair of support portions 3a, 3b that are arranged perpendicular to the grounding portions 2a, 2b and parallel to each other, and whose tip portions are branched upward and downward, a series of circumferential upper heating portions 4α that are provided to connect the upper tips of the pair of support portions 3a, 3b, and a series of circumferential lower heating portions 4β that are provided to connect the lower tips of the pair of support portions 3a, 3b, and a heat release portion R (including a first protruding piece 11, a second protruding piece 12, and a connecting member 13) that protrudes outward from the upper branching portion of the left support portion 3a, and is configured so that AC current from the grounding portions 2a, 2b is supplied to the upper heating portion 4α via the heat release portion R.

[0038] Therefore, the heating coil 1 can reduce the heat generation amount of the upper heating portion 4α compared to the lower heating portion 4β, which is directly supplied with AC current from the ground portions 2a and 2b. Therefore, with the heating coil 1, it is possible to easily control the depth of the hardened layer formed by quenching the workpiece for each height position in accordance with the shape of the workpiece.

[0039] Furthermore, the heating coil 1 is provided with current path length adjustment means (such as the first protruding piece 11 with the slit 15 formed therein, the second protruding piece 12 with the slit 17 formed therein, and the connecting member 13) for adjusting the length of the current flow path inside the heat dissipation part R, and by changing the length of the current flow path inside the heat dissipation part R, the amount of magnetic flux generated in the heat dissipation part R can be changed, thereby changing the amount of heat generated in the upper heating part 4α to which current is supplied via the heat dissipation part R. Therefore, the heating coil 1 makes it very easy to control the depth of the hardened layer caused by quenching for each height position of the workpiece.

[0040] In addition, the heating coil 1 has a current path length adjustment means consisting of a first protruding piece 11 and a second protruding piece 12 formed to protrude outward from the main body of the support portion 3a, and a connecting member 13 that can connect the first protruding piece 11 and the second protruding piece 12 at different positions in the protruding direction. Simply by changing the connecting position of the first protruding piece 11 and the second protruding piece 12, the length of the flow path of the alternating current flowing inside the heat dissipation portion R can be changed, and the amount of magnetic flux generated in the heat dissipation portion R can be changed.This changes the amount of heat generated in the inner part of the upper heating portion 4a of the workpiece, making it extremely easy to control the depth of the hardened layer caused by quenching for each height position of the workpiece.

[0041] In addition, because the heating coil (coil body C) is formed by a modeling method using a three-dimensional printer device M (i.e., a method of partially fusing and laminating conductive material powder layers based on three-dimensional data), it can be manufactured very easily despite the series of circumferential heating portions 4a, 4b having a complex shape including an intermediate heating portion (first conductive portion) 14 and a lower heating portion (second conductive portion) 15, and products having the same shape and characteristics can be manufactured efficiently with good reproducibility regardless of the skill of the manufacturing worker. Furthermore, because the heating coil (coil body C) is formed by a modeling method using a three-dimensional printer device M, there are no adhesive portions bonded by silver brazing as in conventional heating coils, so it does not deform even when the temperature rises during continuous use, and heating treatment (hardening treatment) according to the standard can be performed over a long period of time.

[0042] <Modifications of the heating coil> The heating coil according to the present invention is not limited to the aspects of the above-described embodiment, and the materials, sizes, shapes, structures, and other configurations of the grounding portion, support portion, heating portion (upper heating portion, lower heating portion), heat release portion, coolant flow path, connecting member, fixing member, and the like of the coil body can be appropriately modified as necessary without departing from the spirit of the present invention.

[0043] For example, the heating coil is not limited to the one in which the heating portion is annular in plan view as in the above embodiment, but can be changed to one in which the heating portion is rectangular in plan view, etc.

[0044] Furthermore, the heating coil is not limited to the above embodiment in which the tip of the support part branches into two and is connected to the upper and lower heating parts, and a heat dissipation part is formed in the upper branch part of the support part, but may also be one in which the heat dissipation part is formed in the lower branch part of the support part, or one in which the tip of the support part branches into three or more parts, each connected to a heating part, and a heat dissipation part is formed in any of the branch parts of the support part.

[0045] Furthermore, the heating coil is not limited to the above embodiment in which a heat dissipation portion is formed from a protruding piece (first protruding piece) attached to the support part so that the plate surface faces vertically, a protruding piece (second protruding piece) attached to the support part so that the plate surface faces horizontally, and a connecting member, but may also be formed from a pair of protruding pieces attached to the support part so that the plate surface faces vertically, and a heat dissipation portion formed from a connecting member.

[0046] Furthermore, the heating coil is not limited to the one having a heat dissipation portion formed of a pair of protrusions and a connecting member attached to the support portion as in the above embodiment, but may be one having a heat dissipation portion formed of a U-shaped protrusion in a plan view suspended so as to straddle a vertical slit formed in one of the support portions, etc. In addition, the heating coil is not limited to the one having slits (long holes along the longitudinal direction) in the pair of protrusions formed on the support portion so that the current path length in the heat dissipation portion is adjustable as in the above embodiment, but may be one having a pair of protrusions formed on the support portion with a plurality of screw holes arranged along the longitudinal direction so that the current path length in the heat dissipation portion is adjustable, as in Figure 10.

[0047] In addition, the heating coil is not limited to the above-described embodiment in which the coil body is formed by a partial welding lamination method of conductive material powder layers, or the entire coil body or the coil body is formed by a partial welding lamination method of conductive material powder layers or a melt extrusion lamination method of conductive material, but the entire coil or the coil body may be formed by assembling multiple components by methods such as welding, brazing, or screwing using bolts and nuts, etc.

[0048] The heating coil according to the present invention has the excellent effects as described above, and can therefore be suitably used as a member for heating a workpiece by utilizing electromagnetic induction.

[0049] 1...Heating coil 2a, 2b...Grounding part 3a, 3b...Supporting part 3b ｂ , 3a ｂ ... Base end part 3b ｄ１ , 3a ｄ１ Upper branch portion 3b ｄ２ , 3a ｄ２Lower branch portion 4 Heating portion 4α Upper heating element 4β Lower heating element C Coil body R Heat dissipation portion (part forming a bypass current path)

Claims

1. A heating coil for use in a high-frequency heating device for heating workpieces using electromagnetic induction by high-frequency current, comprising: a pair of plate-shaped grounding sections for contacting electrodes that pass high-frequency current; a pair of support sections that are orthogonal to the grounding sections and arranged parallel to each other, with their tip sections branched into multiple parts; and a series of multiple circumferential heating sections that are provided to connect the tips of the branched sections of the pair of support sections, characterized in that a U-shaped heat dissipation section is formed so as to protrude outward from one of the branched sections formed on one side of the pair of support sections.

2. A heating coil for a high frequency heating device as claimed in claim 1, characterized in that the heat dissipation section is provided with a current path length adjusting means for adjusting the length of the current flowing inside.

3. A heating coil for a high frequency heating device as described in claim 1, characterized in that the current path length adjustment means comprises two protruding pieces formed to protrude outward from the main body of the support part, and a connecting member that can connect the protruding pieces at different positions in the protruding direction.

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