JP3936532B2 - Large spherical induction heating method and heating coil - Google Patents

Description

【００３５】
焼入れの結果を図９、図１０および表２、表３に示す。図９は焼入面の側面形状の詳細を示す図、図１０は図９のＺ視図である。表２は図９、図１０の焼入面の寸法の規格値と実測値を示す。表から分かるように、本発明の方法によれば焼入面の所定の幅と目標としたソフトゾーンが得られた。
【００３６】
【表２】

【００３７】
また、表３は図９、図１０の各位置における焼入硬さの実測値を示すが、焼入硬さも規格値を満足する。以上、これらの表から分かるように、本発明によれば、焼入面寸法、焼入硬さともに十分規格を満足し、予定のソフトゾーンが得られることが分かった。
【００３８】
【表３】

【００３９】
なお、本実施形態では、球面を頭頂部、中間部、側面部に３分割して分割焼入れしたが、球面の大きさによっては頭頂部と中間部を一度に焼入れし側面部と併せて２分割焼入れすることもでき、さらに４分割以上の分割焼入れすることもできる。
【００４０】
【発明の効果】
以上説明したように、本発明の大型球面の誘導加熱焼入方法及び加熱コイルによれば、被焼入部材を回転しながら第１コイル、第２コイル、第３コイルにより被焼入球面の頭頂部円周、中間部円周、側面部円周を分割焼入れするので、大型球面を小さい容量の設備で誘導加熱焼入れすることができる。
【００４１】
また、使用コイルは加熱面に向けて被焼入球面に沿った曲線の導体を有する平面加熱型コイルであり、この第１および第２コイルは、扇形コイルであるので、従来の矩形コイルのように、扇形のソフトゾーンを生ずることなく等幅のソフトゾーンを得ることができる。
【００４２】
また、第１コイルは２巻コイルを使用し、少なくも一つ以上のコイルには磁束集中材が設けられる（本実施例では第２コイル）ので、加熱面を均一加熱する適正な磁束が得られ、かつこの磁束集中材には、冷却液を被焼入球面に噴射する噴射口が設けられているので、急冷が容易であり均一な焼入硬さが得られる。さらに加熱コイルの後方側に冷却液を噴射する冷却ジャケットが設けられて噴射冷却されるので、一層完全な焼入れ冷却を行うことができる。
【００４３】
以上により、従来焼入れが困難であった大型球面の誘導加熱焼入れが比較的小容量の設備で簡易に行うことができ、大型球面部材の原価低減に寄与できる。
【図面の簡単な説明】
【図１】本発明実施形態の誘導加熱焼入れについて説明する図である。
【図２】被焼入球面の頭頂部円周を加熱する第１コイルの斜視図である。
【図３】被焼入球面の中間部円周を加熱する第２コイルの斜視図である。
【図４】被焼入球面の側面部円周を加熱する第３コイルの斜視図である。
【図５】本発明実施形態の磁束集中材の構造を示す一部断面図である。
【図６】本発明と従来焼入れにおけるソフトゾーンの形状の比較を示す図である。
【図７】本発明実施形態の冷却手段の１例を示す図である。
【図８】本発明実施例に使用した被焼入部材の形状を示す図である。
【図９】本発明実施例の焼入面の側面形状の詳細を示す図である。
【図１０】図９のＹ視図である。
【符号の説明】
１ 頭頂部焼入面、２ 中間部焼入面、３ 側面部焼入面、１ａ，２ａ，３ａ，ソフトゾーン、１０ 第１コイル、１１ａ，１１ｂ、１５ａ，１５ｂ、１３、１７ 円周方向導体、１２、１４、１６、１８ 軸方向導体、Ｌ１１，Ｌ１２ リード、２０ 第２コイル、２１ａ，２１ｂ、２３ 円周方向導体、２２、２４軸方向導体、Ｌ２１，Ｌ２２ リード、３０ 第３コイル、３１ａ，３１ｂ、３３ 円周方向導体、３２、３４ 軸方向導体、Ｌ３１，Ｌ３２ リード、４０磁束集中材、４１ ベース体、４１ａ 中空部、４１ｂ 噴射口、４２蓋、４３ 導入管、４５ 冷却ジャケット、４６ 中空管、４７ 噴射口、４８ 導入管 Ｗ ワーク（被焼入部材）、Ｐ 貫通ピン孔[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a large spherical induction heating method and a heating coil for quenching a large spherical surface member, for example, a large spherical member having a large spherical surface portion of 500 mmφ such as a gripper jack used in a tunnel excavator. Is.
[0002]
[Prior art]
In normal surface hardening of a spherical member, induction heating is performed while rotating the object to be heated using a single heating coil having a curved conductor along the spherical surface in the axial direction. The method is taken. As an improvement of this, the present applicant has previously disclosed the inventions of Japanese Utility Model Publication No. 52-49162 and Japanese Utility Model Publication No. 1-41912.
[0003]
In such a heating method, a certain amount of high-speed rotation is required for rotation of the material to be processed in order to uniformly heat the heating unit. However, for example, a shaft member having a weight of 8 tons, such as the gripper jack member, is difficult to rotate at a high speed because it rotates and heats. Therefore, in such a large-sized member, moving quenching is adopted in which the part to be treated is moved and quenched while being heated and cooled.
[0004]
[Problems to be solved by the invention]
However, in the case of the large-sized member as described above, it is difficult to apply a sufficient heating load to heat the entire spherical surface at once with one coil even by moving quenching. It is. For this reason, there is a problem that partial unevenness of the heating temperature occurs, or the heating time becomes long and the thermal efficiency is lowered, and induction heating and quenching is almost impossible with normal equipment. In addition, it is difficult to heat a wide surface of a large spherical surface to a uniform temperature at a time, and it is difficult to obtain a uniform surface hardness.
[0005]
Further, when the spherical head is moved and quenched by a coil of a conductor having a spherical surface, the spherical head of the Japanese Utility Model Publication No. 1-41922 is integrated with a coil having an integral conductor, the circumference of the large diameter of the side surface is smaller than that of the small diameter of the top of the spherical surface. Since the heating rate is slow, the crown that has been quenched once is reheated and tempered, and there is a problem that high hardness cannot be obtained at the crown.
[0006]
In general, in the transfer quenching, a soft zone is formed between the start of quenching and the end of quenching so that the quenching start portion is not reheated. The soft zones are preferably in the form of parallel equal-width zones 1a and 2a as shown in the upper portion of FIG. 6X-X. However, when the spherical surface is quenched with a conventional linear coil indicated by a broken line below the line XX in FIG. 6, fan-shaped soft zones 1a ′ and 2a ′ are formed without equal width as shown in the figure.
[0007]
On the other hand, in the case of quenching a large spherical surface, it is often sufficient that the portion supporting the yield strength is quenched even if it is not the entire surface quenching. Therefore, an object of the present invention is to provide a large spherical induction heating and quenching method and a heating coil which can be quenched with a small capacity electric power facility and have a uniform soft zone in large spherical quenching.
[0008]
[Means for Solving the Problems]
In order to achieve the above-described object, the large spherical induction heating and quenching method of the present invention is configured such that when a hardened member having a large spherical surface is rotated and moved and quenched, the hardened spherical surface is arranged on the circumference of the top and the top of the head. And three side-heating coils having curved conductors along the to-be-hardened spherical surface toward the heating surface . quenching the parietal region circumferential coil, the second coil quenching the intermediate portion circumference of the top portion and side portions, characterized in that the three-part hardening for hardening the side portions circumference by the third coil It is what.
[0009]
That is, a large spherical surface can be heated and hardened with a small electric power equipment by dividing the top part, the intermediate part, the side part and the like into at least two pieces and moving and quenching in this way. Moreover, the softening due to reheating of the top of the head as described above can be prevented, and uniform spherical hardening can be performed.
[0010]
The three induction heating coils for heating and hardening the large spherical surface are all planar heating type coils having curved conductors along the hardened spherical surface toward the heating surface, and the first and second coils are: , Formed by two circumferential conductors of a short arc-shaped curve that connects between two longitudinal conductors of a short arc-shaped curve along the longitude line of the spherical surface and a longitude line of the two axial conductors along the latitude line of the quenching portion. It is a sector coil having a bottom side and a top side.
[0011]
When the top and middle spherical surfaces are heated and hardened by a rectangular coil used for normal planar induction heating, the soft zone 1a 'opened in a fan shape shown at the bottom of line XX in FIG. 6 as described above. Will occur. On the other hand, according to the sector coil of the present invention, the length of the base and the top of the circumferential conductor is a sector having a length corresponding to the interval between the longitude lines formed by the axial conductor. As shown in the upper part of the XX line, the soft zone 1a has a uniform width. Practically, the third coil may be a coil of a conductor having a rectangular shape along the to-be-hardened spherical surface instead of a sector shape.
[0012]
The first coil is preferably a two-turn coil in which a small-diameter sector coil is disposed on the inner peripheral side of a large-diameter sector coil and both coils are connected in series. In this way, the magnetic flux density can be increased and the heating efficiency can be increased.
[0013]
In addition, at least one of the heating coils is preferably provided with a magnetic flux concentrating material on the inner peripheral side of the coil. By so doing, uneven heating can be eliminated by appropriately arranging the magnetic flux concentrating material.
[0014]
Further, it is desirable that the magnetic flux concentrating material is provided with a hollow portion into which the cooling liquid is introduced and an injection port for injecting the cooling liquid introduced into the hollow portion onto the hardened spherical surface. In this way, since the coolant can be sprayed directly and uniformly onto the heating surface immediately after heating, rapid quenching is easy and uniform quenching hardness is obtained.
[0015]
In addition, by providing a cooling jacket for injecting a coolant on the rear side of the heating coil, rapid quenching after heating is further facilitated in moving quenching, and uniform quenching hardness is obtained.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described with reference to an illustrated embodiment. FIG. 1 is a diagram for explaining induction heating and quenching according to the present invention, FIG. 2 is a perspective view of a first coil for heating the circumference of the top of the spherical surface to be hardened, and FIG. 3 is a circumference of the middle between the top and side portions. FIG. 4 is a perspective view of the third coil for heating the circumference of the side surface portion. FIG. 5 is a partial cross-sectional view showing the structure of the magnetic flux concentrating material of the present invention, FIG. 6 is a diagram showing a comparison of the shape of the soft zone in the present invention and conventional quenching, and FIG. 7 is a diagram showing an example of cooling means. 8 is a figure which shows the shape of the to-be-hardened member used for this invention Example.
[0017]
Referring to FIG. 1, the induction heating quenching of the present invention quenches the to-be-quenched spherical surface of the head W1 of a member to be quenched (hereinafter referred to as a workpiece) W. An example of the workpiece is a large member having a spherical diameter of 590 mm, a length of 3300 mm, and 8 tons as shown in FIG.
[0018]
In the quenching method, first, the top of the spherical surface of the workpiece W to be hardened is heated and cooled by the first coil 10, and the workpiece W is rotated once to move and quench the top of the workpiece W to form the quenching surface 1. Next, after heating and cooling the intermediate part between the top part and the side part by the second coil 20, the workpiece W is similarly rotated to move and quench the intermediate part to form the quenching surface 2, and then the side part 3 is moved. The workpiece W is rotated and moved and quenched in the same manner while being heated and cooled by the third coil 30 to form the quenched surface 3.
[0019]
At this time, the soft zones 1a, 2a, etc. are formed at the position rotated once so as not to affect the heat at the beginning of quenching. In the present embodiment shown in FIG. 1, since the through hole P is provided in the spherical surface portion of the workpiece, the soft zones 3 a are formed on both sides of the through hole P. Soft zones are also formed between the quenching surface 1 at the top and the quenching surface 2 at the intermediate portion, and between the quenching surface 2 at the intermediate portion and the quenching surface 3 at the side portion. It is desirable to shift the positions of the soft zones 1a, 2a and 3a of the quenching surfaces 1, 2 and 3 at the top, middle and side portions in the circumferential direction as shown in the figure. Details of this soft zone will be described later.
[0020]
A first coil 10 of the present invention shown in FIG. 2 is a fan-shaped coil, and has a large-diameter sector coil in which circumferential conductors 11a, 11b and 13 and axial conductors 12, 14 are alternately connected, and an inner circumference thereof. A similar small-diameter sector coil in which circumferential conductors 15a, 15b and 17 and axial conductors 16 and 18 are alternately connected to each other from a two-turn coil connected in series by 11b and 15a Become. The terminal T11 is connected to the lead portion L11 connected to the circumferential conductor 11a of the large-diameter coil, the terminal T12 is connected to the lead portion L12 connected to the circumferential conductor 15b of the small-diameter coil, and the terminal T11. , T12 is used to input power.
[0021]
The conductors of these coils form a curve along the spherical surface that forms a predetermined gap with the spherical surface of the workpiece. The axial conductors 12, 14 and 16, 18 of the large-diameter coil and the small-diameter coil are each composed of a short arc-shaped conductor having a curved line along a spherical longitude line as shown by broken lines in the figure, and are arranged at predetermined intervals.
[0022]
Further, the circumferential conductors 11a, 11b and 13 and 15a, 15b and 17 of the large-diameter coil and the small-diameter coil are similarly short arc-shaped conductors along the latitude line on the spherical surface at the respective positions as indicated by broken lines. The both ends of the hardened surface are connected to the axial conductor. Thereby, the length of the circumferential conductor becomes a length corresponding to the interval between the longitude lines formed by the axial conductors, and the coil forms a sector. The respective conductors are connected such that current flows from the lead L11 to the lead L12 through the conductors 11a-12-13-14-11b-15a-16-17-18-15b as indicated by arrows.
[0023]
The second coil 20 shown in FIG. 3 is similar to the first coil, but the second coil 20 is a one-turn coil. The axial conductors 22 and 24 are each composed of a short arc-shaped conductor having a curve along the longitude line of the intermediate surface of the spherical surface. Further, the circumferential conductors 21a, 21b and 23 are composed of short arc-shaped conductors along the latitude line of the spherical intermediate surface 2, and the length of each circumferential conductor is the longitude formed by the axial conductor. The length corresponds to the interval between the lines. Thereby, the 2nd coil 20 also makes a fan-shaped coil. And each conductor is connected so that an electric current may flow into the arrow of a figure.
[0024]
The third coil 30 for heating the spherical side surface shown in FIG. 4 is the same as the second coil 20, but the axial conductors 32 and 34 extend over the upper and lower hemispheres, and are practically rectangular coils. good. Others are the same as those of the second coil 20.
[0025]
As shown in FIG. 5, the magnetic flux concentrating material is attached to the second coil 20 on the inner peripheral side of the coil. FIG. 5A is a partial cross-sectional view of the plane of the magnetic flux concentrating material attached to the second coil 20, and FIG. 5B is a YY cross-sectional view of FIG.
[0026]
In the figure, the magnetic flux concentrating member 40 includes a base body 41 and a lid 42. A hollow portion 41a is dug in the base body 41, and a large number of injection ports 41b for injecting a coolant from the hollow portion 41a toward the workpiece are penetrated. A magnetic lid 42 is bonded onto the base body 41 so that the hollow portion 41a forms a cavity. An introduction tube 43 is bonded to the lid 42. Thereby, after heating a workpiece | work, the cooling fluid introduce | transduced into the hollow part 41a from the introductory tube 43 is injected to the workpiece | work surface from the injection port 41b, and it cools rapidly.
[0027]
As a cooling means, in addition to cooling from the magnetic flux concentrating material, a cooling jacket shown in FIG. 7 is mounted as an example. FIG. 7 is a view showing a cooling jacket mounted on the third coil 30, but the same applies to the first and second coils. That is, a cooling jacket 45 is disposed behind the conductors 32 and 34 of the third coil 30 in the traveling direction, and immediately after being heated by the third coil while moving the workpiece, the cooling jacket 45 is rapidly cooled and quenched. is there.
[0028]
The cooling jacket 45 is provided with an injection port 47 in a triangular cross-section hollow tube 46 disposed in parallel to the conductor 34 behind the third coil 30 in the traveling direction, and from the water conduit 48 to the hollow portion of the hollow tube 46. The introduced cooling liquid is jetted onto the work from the jet 47 to cool it.
[0029]
Hereinafter, a quenching operation using the quenching coil having the above-described configuration will be described with reference to FIGS. First, the terminals T11 and T12 of the first coil 10 are connected to a high-frequency power source (not shown), and the top of the head so that the conductors 11a, 11b, 12, 13, 14. Is disposed at a predetermined position. And electric power is input into terminal T11, T12, and a top part is induction-heated. When the surface to be quenched rises to the quenching temperature, the workpiece is rotated and the surface heated by the cooling jacket 45 is cooled and quenched. Thereafter, the workpiece is rotated at a speed at which the quenching surface is heated to the quenching temperature, and the workpiece is quenched by heating and cooling while continuously rotating. When the workpiece is rotated once, a soft zone 1a as shown in FIGS. 1 and 6 is formed to stop the rotation of the workpiece. As a result, a hardened and hardened surface as shown in the upper part of line XX in FIG. 6 is formed. However, in the present invention, since a fan-shaped heating coil is used, the soft zone 1a has a uniform width as shown in the figure. Become. During cooling, the second coil cools by injecting the cooling liquid from the injection port 41b of the magnetic flux concentrating material 40, so that a further rapid cooling effect can be obtained.
[0030]
When the top hardened surface 1 is formed, the intermediate hardened surface 2 is then formed. Similarly to the first coil, the second coil 20 is connected to a high-frequency power source (not shown) and disposed at a predetermined position in the intermediate portion of the workpiece. Then, an intermediate hardened surface 2 is formed by the same operation as the top hardened surface 1. Also in this case, the soft zone 2a has the same width. As described above, it is desirable that the positions of the soft zone 1a of the quenching surface 1 at the top and the soft zone 2a of the quenching surface 2 at the intermediate portion are shifted in the circumferential direction.
[0031]
When the quenching surface 1 at the top and the quenching surface 2 at the intermediate portion are formed, the quenching surface 3 at the side surface is formed by the third coil by the same operation. Since the work of the present embodiment in FIG. 1 is provided with through-pin holes P in the spherical portion, soft zones 3a are formed on both sides of the holes (FIG. 6 shows a case without holes).
[0032]
The quenching surfaces 1, 2, and 3 are quenched by the above method to complete the quenching operation. As shown in the figure, the shape of the hardened surface includes the soft zone, the top hardened surface 1 and the intermediate hardened surface 2, and the intermediate hardened surface 2 and the side hardened surface. A soft zone is formed between the surface 3 and the surface 3.
[0033]
[Example]
The Example which hardened on the following conditions by the said method is demonstrated.
Shape of work: A member having a length of 3300 mm having a penetrating pin hole P on a spherical head of 590 mmφ shown in FIG. 8 and a material of about 8 tons work: SCM440
Heating conditions: As shown in Table 1
[Table 1]

[0035]
The results of quenching are shown in FIGS. 9 and 10 and Tables 2 and 3. FIG. 9 is a diagram showing details of the side surface shape of the hardened surface, and FIG. 10 is a Z view of FIG. Table 2 shows the standard value and the actual measurement value of the dimension of the hardened surface in FIGS. 9 and 10. As can be seen from the table, according to the method of the present invention, a predetermined width of the hardened surface and a target soft zone were obtained.
[0036]
[Table 2]

[0037]
Table 3 shows the measured values of the quenching hardness at the respective positions in FIGS. 9 and 10, and the quenching hardness also satisfies the standard value. As described above, as can be seen from these tables, it was found that according to the present invention, the hardened surface dimensions and the hardened hardness sufficiently satisfy the standards, and a planned soft zone can be obtained.
[0038]
[Table 3]

[0039]
In this embodiment, the spherical surface is divided into three parts, the top part, the intermediate part, and the side part, and is divided and hardened. However, depending on the size of the spherical surface, the top part and the intermediate part are quenched at one time and divided into two parts together with the side part. Quenching can also be performed, and further, four or more divided quenching can be performed.
[0040]
【The invention's effect】
As explained above, according to the large spherical induction heating and hardening method and heating coil of the present invention, the head of the hardened spherical surface is rotated by the first coil, the second coil, and the third coil while rotating the hardened member. Since the top circumference, the middle circumference, and the side circumference are divided and quenched, the large spherical surface can be induction-heat quenched with equipment having a small capacity.
[0041]
The coil used is a plane heating type coil having a curved conductor along the hardened spherical surface toward the heating surface. Since the first and second coils are fan coils, they are like conventional rectangular coils. In addition, a uniform soft zone can be obtained without generating a sector-shaped soft zone.
[0042]
In addition, since the first coil uses a two-turn coil and at least one coil is provided with a magnetic flux concentrating material (in this embodiment, the second coil), an appropriate magnetic flux for uniformly heating the heating surface is obtained. In addition, since the magnetic flux concentrating material is provided with an injection port for injecting the cooling liquid onto the hardened spherical surface, it is easy to rapidly cool and uniform hardening hardness is obtained. Furthermore, since a cooling jacket for injecting a cooling liquid is provided on the rear side of the heating coil to perform injection cooling, more complete quenching cooling can be performed.
[0043]
As described above, induction heating and quenching of a large spherical surface, which has conventionally been difficult to quench, can be easily performed with a relatively small capacity facility, and can contribute to cost reduction of the large spherical member.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating induction heating quenching according to an embodiment of the present invention.
FIG. 2 is a perspective view of a first coil that heats the top circumference of a hardened spherical surface.
FIG. 3 is a perspective view of a second coil that heats the circumference of an intermediate portion of a hardened spherical surface.
FIG. 4 is a perspective view of a third coil that heats the circumference of the side surface portion of the hardened spherical surface.
FIG. 5 is a partial cross-sectional view showing a structure of a magnetic flux concentrating material according to an embodiment of the present invention.
FIG. 6 is a diagram showing a comparison of soft zone shapes between the present invention and conventional quenching.
FIG. 7 is a diagram showing an example of cooling means according to an embodiment of the present invention.
FIG. 8 is a view showing the shape of a member to be hardened used in an embodiment of the present invention.
FIG. 9 is a diagram showing details of the side surface shape of the hardened surface of the embodiment of the present invention.
10 is a Y view of FIG. 9. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Head part hardened surface, 2 Middle part hardened surface, 3 Side part hardened surface, 1a, 2a, 3a, Soft zone, 10 1st coil, 11a, 11b, 15a, 15b, 13, 17 Circumferential conductor 12, 14, 16, 18 Axial conductor, L11, L12 lead, 20 Second coil, 21a, 21b, 23 Circumferential conductor, 22, 24 Axial conductor, L21, L22 lead, 30 Third coil, 31a , 31b, 33 Circumferential conductor, 32, 34 Axial conductor, L31, L32 lead, 40 magnetic flux concentrating material, 41 base body, 41a hollow part, 41b injection port, 42 lid, 43 introduction pipe, 45 cooling jacket, 46 Hollow tube, 47 injection port, 48 Introductory tube W Workpiece (hardened member), P Through pin hole

Claims (6)

When rotating and quenching a hardened member having a large spherical surface, the hardened spherical surface is divided into a top circumference, a middle circumference between the top and the side and a side circumference, and the heating. Using three planar heating type coils having curved conductors along the hardened sphere toward the surface, the top coil periphery is quenched with a first coil and the top and side surfaces with a second coil A large spherical induction heating method characterized by quenching an intermediate part circumference of the part and quenching the side part circumference by a third coil . When rotating and quenching a hardened member having a large spherical surface, the circumference of the top of the hardened spherical surface is quenched by the first coil, and the circumference of the intermediate portion between the top and the side by the second coil. In the induction heating coil that performs the three-part quenching in which the side surface circumference is quenched by the third coil, the three heating coils have curved conductors along the hardened spherical surface toward the heating surface. The first and second coils are planar heating coils, and the first and second coils have two axial conductors having a short arc shape along a spherical longitude line and the longitudes of the two axial conductors along a latitudinal line of a hardened portion. A large spherical induction heating coil characterized in that it is a sector coil having a bottom and a top formed by a short arc-shaped circumferential conductor connecting between the lines. 3. The large spherical surface according to claim 2 , wherein the first coil is a two-turn coil in which a small-diameter fan coil is disposed on an inner peripheral side of a large-diameter fan coil and both coils are connected in series. Induction heating coil. The large spherical induction heating coil according to claim 2 or 3 , wherein at least one of the heating coils is provided with a magnetic flux concentrating material on an inner peripheral side of the coil. Wherein the flux concentration member includes a hollow portion in which the cooling liquid is introduced, a cooling liquid introduced into the hollow portion to claim 4, characterized in that the injection port for injecting the target hardening sphere is provided Large spherical induction heating coil as described. The large spherical induction heating coil according to any one of claims 2 to 5 , wherein the heating coil is provided with a cooling jacket for injecting a cooling liquid on a moving rear side.

Images