JP2015118881A - Induction heating coil and induction heating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating coil and an induction heating method for inductively heating a work-piece in which a groove is formed along an axis in a longer direction.SOLUTION: An induction heating coil 1 comprises a first conductor 10 and a second conductor 20. The first conductor 10 is formed by orbit parts 11, 12 which are coaxially arranged at a distance from each other and connected with each other and each of the orbit parts 11, 12 orbits the work-piece 30 around an axis of the work-piece 30. The second conductor 20 has a projection 21 so as to face the groove 31 of the work-piece 30 and is arranged between the orbit part 11 and the orbit part 12. Any of the induction heating coil 1 and the work-piece 30 is moved in an axial direction while passing a high-frequency current through the induction heating coil 1 with the work-piece 30 being inserted into the orbit parts 11, 12 of the induction heating coil 1.

Description

  The present invention relates to an induction heating coil and an induction heating method for induction heating a workpiece in which a groove is provided along a longitudinal axis.

  In order to quench the surface of the cylindrical workpiece, the outer peripheral surface is heated by an induction heating coil (for example, Patent Documents 1 and 2). In Patent Documents 1 and 2, the induction heating coil includes a fixed coil for heating and a movable coil for adjusting the heating range, and the movable coil is moved in the axial length direction of the workpiece, so that The axial heating range can be adjusted.

Japanese Patent No. 2913615 Japanese Patent No. 3117008

  As described above, in the induction heating coils disclosed in Patent Documents 1 and 2, induction heating can be performed by specifying the length in the axial direction of the surface of the cylindrical workpiece. However, the cylindrical workpiece to be induction-heated differs in the axial cross-section in the axial longitudinal direction, and the groove is opened toward the outer peripheral side by sinking a part or all of the hollow tube body into the longitudinal direction. In the case of being provided along the direction axis, the induction heating coils disclosed in Patent Documents 1 and 2 cannot be used.

  Then, an object of this invention is to provide the induction heating coil and induction heating method which carry out induction heating of the workpiece | work in which a groove part is provided along the axis | shaft of a longitudinal direction.

In order to achieve the above object, the induction heating coil of the present invention comprises:
An induction heating coil for heating a workpiece in which a groove is provided along a longitudinal axis,
A first conductor in which a revolving part that circulates the work around an axis of the work is arranged coaxially at an interval, and the revolving parts are connected to each other;
A second conductor having a projecting portion so as to face the groove portion of the workpiece, and being arranged between the circulating portions and causing an induced current to flow through the circulating portion;
Is provided.

  In order to achieve the above object, the induction heating method according to the present invention inserts the work into the induction heating coil according to the present invention and heats the work in which the groove is provided along the longitudinal axis. Either the heating coil or the workpiece is moved in the axial direction.

  According to the induction heating coil of the present invention, the first conductor is disposed around the workpiece around the axis of the workpiece at a coaxial interval, and the second conductor faces the protruding portion toward the workpiece groove. Since the second conductor is disposed between the surrounding portions, an induced current flows through the second conductor and the workpiece by flowing current through the surrounding portion. Therefore, the work in which the groove portion is provided along the longitudinal axis can be induction-heated including the groove portion.

  According to the induction heating method of the present invention, the work is inserted through the induction heating coil of the present invention, and the induction heating coil and the work are relatively moved in the axial direction of the work. Thereby, when the induction heating coil overlaps the region to be heated of the workpiece, an induced current can be generated in the groove portion and the back surface portion of the workpiece by flowing a current through the induction heating coil.

It is a top view of the induction heating coil which concerns on embodiment of this invention. It is a front view of the induction heating coil shown in FIG. The workpiece | work heated by the induction heating coil shown in FIG. 1 is shown typically, (a) is a perspective view, (b) is an end view along XX line, (c) is X shown in FIG.3 (b). It is an end view which shows another form different from the end surface along -X-ray. It is a figure which shows typically the process of induction-heating a workpiece | work using the induction heating coil shown in FIG. (A) is a figure which shows the result of an Example, (b) is a figure which shows the result of a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Induction heating coil]
FIG. 1 is a plan view of an induction heating coil 1 according to an embodiment of the present invention, and FIG. 2 is a front view of the induction heating coil 1 shown in FIG. The induction heating coil 1 according to the embodiment of the present invention is used when heating a workpiece 30 in which the groove portion 31 is provided along the longitudinal axis. The induction heating coil 1 includes a first conductor 10 and a second conductor 20.

  The first conductor 10 is configured by connecting the circumferential portions 11 and 12 that are arranged coaxially at intervals, and each of the circumferential portions 11 and 12 circulates the workpiece 30 around the axis of the workpiece 30. The second conductor 20 has a protruding portion 21 so as to face the groove portion 31 of the workpiece 30, and is disposed between the rotating portion 11 and the rotating portion 12. The workpiece 30 can be inserted through the hollow portions 11 and 12 of the first conductor 10, and the protruding portion 21 of the second conductor 20 can be put in and out of the groove portion 31 of the workpiece 30. Then, current is passed through the first conductor 10 to inductively heat the work 30. At this time, an induced current flows from the first conductor 10 to the second conductor 20, and this induced current further induces an induced magnetic field in the groove 31 and the vicinity thereof. Can be generated. As described above, by inserting the protruding portion 21 into the groove portion 31 of the workpiece 30 so that the protruding portion 21 faces the groove portion 31, an induced current can easily flow through the groove portion 31 of the workpiece 30.

  The 1st conductor 10 has the dimension which can circulate the workpiece | work 30 shown with a dashed-two dotted line in FIG. Therefore, even when the depth of the groove portion 31 is changed in the axial direction of the workpiece 30, or even when the groove portion 31 is not partially formed, the workpiece is covered over the entire axial length of the workpiece 30. 30 can be passed through the first conductor 10. As will be described later with reference to FIG. 3, for example, the first conductor 10 circulates around the workpiece 30 even when induction heating is performed on the workpiece 30 in which the groove portions 31 are not formed at both ends of the workpiece 30. The protruding portion 21 of the second conductor 20 can be inserted into the groove portion 31 or the protruding portion 21 can be taken out of the groove portion 31 in the state.

  Here, before describing the induction heating coil 1 shown in FIGS. 1 and 2 in detail, an example of the workpiece 30 heated by the induction heating coil 1 will be described. FIG. 3 schematically shows an example of the workpiece 30, (a) is a perspective view, (b) is an end view taken along line XX, and (c) is taken along line XX shown in FIG. 3 (b). It is an end view which shows another form different from the end surface which follows.

  As shown in FIG. 3 (a), the workpiece 30 is formed of, for example, a hollow tube or a solid long body whose cross section is a circle, an ellipse, or a polygon, and a groove portion along the axial direction, that is, the longitudinal direction. Or it has the recessed part (in this application, these are named generically and are called a groove part) 31, and the part X1 except the both ends of the area | region in which the groove part 31 is formed is set as an area | region which should be heated. A groove is not formed in one end 36 and the other end 37 of the work 30.

  The groove portion 31 of the workpiece 30 will be described in detail. The work 30 has a groove 31 along the longitudinal direction. One inner portion 32a and the other inner portion 32b are bent at an acute angle to form a groove bottom portion 33. One outer portion 34a is disposed along one inner portion 32a, and the other outer portion 34b is disposed along the other inner portion 32b. One inner edge 32a and one outer edge 34a are connected to form one opening edge 35a, and the other inner edge 32b and the other outer edge 34b are connected to form the other opening edge 35b. Yes. Such a workpiece 30 presses the hollow tube so that a part of the peripheral wall of the hollow tube is depressed toward the inside of the hollow tube except for both ends of the hollow tube as a material. It can be manufactured by molding. As shown in FIG. 3B, the opening edge portions 35a and 35b of the workpiece 30 are different in that they are slightly swollen as compared with FIG. 3C. Other than that, FIG. 3B and FIG. The shape of the workpiece 30 is substantially the same as (c). In the embodiment of the present invention, the shape of the opening edge portions 35a and 35b does not have a bulge as shown in FIG. 3 (c) even if it has a bulge as shown in FIG. 3 (b). The embodiment of the present invention can be applied to any workpiece that may be curved and is a workpiece in which the groove 31 is provided along the longitudinal axis.

  The embodiment shown in FIG. 1 and FIG. 2 is manufactured so as to be suitable for induction heating of the workpiece 30 illustrated in FIG. 3, and the specific configuration is as follows. The first conductor 10 is preferably configured such that the two-stage circumferential portions 11 and 12 are arranged coaxially with an interval, and the two-stage circumferential portions 11 and 12 are connected in series or in parallel. Both ends of one circulating portion 11 are close to each other, and both ends of the other rotating portion 12 are close to each other. A lead portion 13 is connected to one end of one of the surrounding portions 11, a connecting portion 14 extends in the vertical direction to the other end of the one surrounding portion 11, and is connected to one end of the other surrounding portion 12. A lead portion 15 is connected to the other end. Thereby, the circulation part 11 and the circulation part 12 are connected in series. The lead parts 13 and 15 are connected to a high frequency power source via a matching unit.

  The second conductor 20 is disposed in a gap between the circulating portion 11 and the circulating portion 12 of the first conductor 10, and a moving mechanism (not shown) is connected to the second conductor 20, and a part of the second conductor 20 is connected by the moving mechanism. Is put into and out of the groove 31 of the workpiece 30. As a result, when a high-frequency current flows through the two-stage circulating portions 11 and 12, an induced magnetic field is generated in the second conductor 20, an induced current flows, and an induced magnetic field is generated in the groove portion 31 and its surroundings.

  The second conductor 20 is disposed toward the opening of the groove portion 31 of the work 30, and extends along the protruding portion 21 having a shape along the cross-sectional shape of the groove portion 31 of the work 30 and the surrounding portions 11 and 12 of the first conductor 10. And a bending portion 22 that is partially disposed, and a connecting portion 23 that connects the protruding portion 21 and the bending portion 22. The protruding portion 21, the curved portion 22, and the connecting portion 23 are separately joined, but may be integrally formed. If the protruding portion 21 of the second conductor 20 has a shape along the cross-sectional shape of the groove portion 31 of the workpiece 30, the protruding portion 21 is inserted into the groove portion 31 of the workpiece 30. An induction magnetic field can be efficiently generated in the vicinity.

  As shown in FIG. 1, when the groove portion 31 of the workpiece 30 has a V-shaped cross section, the protruding portion 21 is configured by a V-shaped hollow conductor along the groove portion 31 of the workpiece 30. That is, the protruding portion 21 includes one protruding portion 21 a that extends linearly along one inner portion 32 a of the groove portion 31 of the workpiece 30 and the other protruding portion that extends linearly along the other inner portion 32 b of the workpiece 30. The portion 21b is formed by joining at an acute angle, and as a result, has a V shape in plan view. If the groove part 31 is U-shaped, the protrusion part 21 is comprised by the U-shaped hollow conductor.

  The curved portion 22 has a larger curvature than the two-stage rotating portions 11 and 12 of the first conductor 10. In a state in which the protruding portion 21 of the second conductor 20 is inserted into the groove portion 31, the curved portion 22 is arranged on the inner side, which is the center side of the surrounding portions 11 and 12, so as not to overlap the surrounding portions 11 and 12 in plan view. Be placed. Thereby, an induced current efficiently flows from the first conductor 10 to the second conductor 20.

  The connection part 23 is connected by the front-end | tip of one protrusion part 21a, and the front-end | tip of the other protrusion part 21b. Therefore, it consists of a pair of each connection part 23a, 23b which makes L shape by planar view. The bending portion 22 is connected to the tips of the connecting portions 23a and 23b that make a pair. The curved portion 22 of the second conductor 20 has a central angle similar to the angle of the groove portion 31 of the workpiece 30 in a state where the second conductor 20 is inserted into the groove portion 31. Further, since the arc portion of the second conductor is disposed along the circumference of the first conductor, an induced current can be efficiently generated from the circumference of the first conductor to the arc portion of the second conductor. .

  The reason why the first conductor 10 is preferably configured by connecting the winding portions 11 and 12 in series will be described. One rotating part 11 is close to both ends thereof, and the other rotating part 12 is close to both ends thereof. In other words, the revolving parts 11 and 12 are not necessarily annular. In each of the revolving parts 11 and 12, each end approaches but has a gap, and a high-frequency current does not flow in the gap, and therefore a portion where a magnetic field does not occur around the axis occurs. In the embodiment of the present invention, the work 30 is not rotated. In view of this, the first conductor 10 is configured not to be a one-stage winding portion, but preferably to have a current flow in the forward winding direction at the two-stage winding portions 11 and 12. Even if the work 30 is not rotated around the axis, the induction magnetic field can be generated as uniformly as possible around the axis of the work 30 from the circulating portions 11 and 12.

  An insulating sheet (not shown) may be interposed between the surrounding portions 11 and 12 of the first conductor 10 and the second conductor 20, particularly between the surrounding portions 11 and 12 and the curved portion 22, or The insulating sheet material 26 may be fixed to a portion where the first conductor 10 and the second conductor 20 can face each other, for example, the facing surface of the curved portions 22 and the surrounding portions 11 and 12. Thereby, generation | occurrence | production of a spark can be suppressed between the 1st conductor 10 and the 2nd conductor 20. FIG.

  In the first conductor 10, non-conductive support portions 16 a and 16 b are arranged to extend in the vertical direction and are fixed to the surrounding portions 11 and 12. As a result, it is possible to maintain the one circulating portion 11 and the other circulating portion 12 horizontally while maintaining a constant spacing.

  Both the first conductor 10 and the second conductor 20 are formed by connecting hollow conductor members having a predetermined shape by brazing or the like. Thereby, a cooling liquid can be inject | poured from the outside, it can be made to flow through a hollow conductor member, can be cooled, and can be discharged | emitted outside. Although the coolant inlet and outlet for the first conductor 10 are not shown, they are provided, for example, in the lead portions 13 and 15.

  In the second conductor 20, a partition member 24, preferably a conductive partition member 24, is provided in the middle of the curved portion 22, and the pipe connection portions 25 a and 25 b are respectively connected to the curved portions 22 a and 22 b on both sides of the partition member 24. 25b is attached toward the outside.

  The work 30 may be induction-heated by arranging the work 30 along the axis of the surrounding parts 11 and 12 of the first conductor 10 without using the second conductor 20 and flowing a high-frequency current from the lead parts 13 and 15. Conceivable.

  However, if the protrusion 21 is not inserted into the groove 31, the gap between the protrusion 21 and the groove 31 of the workpiece 30 is large, and the induced current from the protrusion 21 to the groove 31 is distributed and flows. Then, a large induced current flows on the side opposite to the groove portion 31 of the workpiece 30, that is, on the back portion 38 side of the lead portions 13 and 15, and only the back portion 38 side of the workpiece 30 is partially heated. It becomes a state of heating.

  Therefore, as in the embodiment of the present invention, the protruding portion 21 is inserted into the groove portion 31, and the bending portion 22 and the surrounding portions 11, 12 are easily electromagnetically coupled to each other from the lead portions 13, 15 to the surrounding portions 11, A current is supplied to 12. Then, an induced current flows through the bending portion 22 and the induced current flows through the protruding portion 21 via the connecting portion 23. An induced current flows in the inner portions 32a and 32b of the workpiece 30 due to the influence of the induced magnetic field due to the protrusions 21a and 21b, and an induced magnetic field due to the coupling portions 23a and 23b in the opening edge portions 35a and 35b of the workpiece 30. Inductive current flows under the influence of the external portion 34a, 34b, and the outer portions 34a, 34b are affected by the induced magnetic field by the portions on the lead portions 13, 15 side of the rotating portion 11, that is, the portions facing the outer portions 34a, 34b. An induced current flows. Thus, by superimposing the magnetic field generated by the circulating portions 11 and 12 and the magnetic field generated by the second conductor 20 such as the protruding portion 21, the temperature can be raised regardless of the part of the work 30.

  Thus, by inserting the protruding portion 21 into the groove portion 31, the induced current flows from the protruding portion 21 to the groove portion 31 of the work 30 without being dispersed, and the groove portions 31 of the inner portions 32a and 32b and the outer portions 34a and 34b An induced current can be caused to flow in an annular manner with respect to the back surface portion 38, and a current can flow uniformly in the circumferential direction of the cross section of the work 30, thereby heating the work 30 uniformly.

[Induction heating method]
As shown in FIG. 3, the induction heating method according to the embodiment of the present invention is used when heating a workpiece 30 in which the groove portion 31 is provided along the longitudinal axis. The work 30 is inserted through the induction heating coil 1 according to the embodiment of the present invention, and either the induction heating coil 1 or the work 30 is moved in the axial direction. Thereby, when the induction heating coil 1 overlaps the region to be heated in the work 30, an induction current can be generated in the groove portion 31 and the back surface portion 38 of the work 30 by flowing a current through the induction heating coil 1. .

  At that time, it is preferable to relatively move either the induction heating coil 1 or the workpiece 30 so that the gap between the protruding portion 21 of the induction heating coil 1 and the groove portion 31 of the workpiece 30 is within a certain range. Thereby, an induced current can be efficiently generated not only in the back surface portion 38 of the workpiece 30 but also in the groove portion 31, and the workpiece 30 can be heated uniformly, for example, at a transformation point temperature or higher.

  More specifically, a movement mechanism (not shown) is attached to the induction heating coil 1, and the movement mechanism moves the induction heating coil 1 in the horizontal biaxial direction. Therefore, the second conductor 20 can be moved in the horizontal direction so that the protrusion 21 can be inserted into and removed from the groove 31 of the work 30. In a state where the end portions 36 and 37 of the work 30 are inserted through the first conductor 10, the protruding portion 21 is not inserted into the groove portion 31, while the intermediate portion of the work 30 is inserted through the first conductor 10. In the state, the protrusion 21 can be inserted into the groove 31. Thereby, even if the depth of the groove part 31 of the workpiece 30 is changed in the axial direction, even if the groove part 31 of the workpiece 30 is not linearly extended and bent, depending on the shape of the groove part 31 of the workpiece 30. The groove 31 of the work 30 can be induction heated.

  The protruding portion 21 is inserted into the groove portion 31, and preferably, the gap between the protruding portion 21 and the groove portion 31 is set within a predetermined fixed range in accordance with the depth of the groove portion 31, so that the protruding portion 21 changes to the groove portion 31 of the workpiece 30. The induced current flows without being dispersed, and the induced current can be caused to flow annularly through the groove portion 31 of the work 30 and the back surface portion 38 of the work 30. Therefore, a current flows uniformly in the circumferential direction of the cross section of the work 30, and the work 30 can be heated uniformly by adjusting the magnitude of the current flowing through the induction heating coil 1.

Below, as shown in FIG. 3, the case where the workpiece | work 30 in which the groove part 31 is formed along the longitudinal direction in the intermediate part except the both ends 36 and 37 of the workpiece | work 30 is mentioned as an example.
A method for induction heating the portion X1 of the groove portion 31 of the workpiece 30 shown in FIG. 3 using the induction heating coil 1 shown in FIGS. FIG. 4 is a diagram schematically showing a process of induction heating a workpiece using the induction heating coil shown in FIG. 4A to 4D, in order to heat the groove 31 of the workpiece, the protrusion 21 of the second conductor 20 is inserted into the heating start point S in the groove 31 of the workpiece 30, The second conductor 20 is slid along the groove 31 to the heating end point F in the groove 31 of the work 30. And at this heating end point F, by pulling out the protruding portion 21 of the second conductor 20 from the groove portion 31 of the workpiece, heating of a predetermined portion of the groove 31 is completed. At this time, either the workpiece 30 or the induction heating coil 1 may be moved.

  More specifically, first, the induction heating coil 1 is horizontally arranged such that the central axis of the induction heating coil 1 according to the embodiment of the present invention is in the vertical direction, and the first conductor 10 has the surrounding portions 11 and 12. One end of the work 30 is inserted. For example, as shown in FIG. 4A, a hollow jacket 40 for injecting quenching liquid is disposed below the surrounding portions 11 and 12 of the first conductor 10, and coaxially above the jacket 40. Two-stage rotating portions 11 and 12 are arranged. At this time, the protruding portion 21 of the second conductor 20 is not inserted into the hollow portions 11 and 12. In such a state, the lower end side of the workpiece 30 is inserted coaxially into the two-stage rotating portions 11 and 12. Note that chuck mechanisms 41 and 41 are respectively attached to the upper end portion and the lower end portion of the work 30, and the chuck mechanisms 41 and 41 are moved in conjunction with the vertical direction by a moving mechanism (not shown).

  Next, as shown in FIG. 4A, the movement of the workpiece 30 in the longitudinal direction is started without inserting the protruding portion 21 of the second conductor 20 into the groove portion 31 of the workpiece 30. Then, when one end of the groove portion 31 of the workpiece 30 passes through the upper circumferential portion 11 of the first conductor 10, the protruding portion 21 of the second conductor 20 is inserted into the groove portion 31 of the workpiece 30. This is the heating start point S of the groove 31 and FIG. 4B shows this state.

  The second conductor 20 is relatively moved by a moving mechanism (not shown), and a high-frequency current is passed through the first conductor 10 simultaneously with or before and after the protrusion 21 is inserted into the groove 31. As a result, the first conductor 10 and the second conductor 20 inductively heat the overlapping portions of the work 30 that are inserted into the surrounding portions 11 and 12 of the induction heating coil 1.

  When the upper and lower chuck mechanisms 41, 41 are moved downward by the moving mechanism, the work 30 is lowered along the longitudinal direction. Thereby, the area | region which should heat the workpiece | work 30 moves to the upper end from the lower end of an intermediate part.

  Further, the second conductor 20 is taken out from the groove 31 of the work 30 before the upper end of the groove 31 of the work 30 passes through the upper circumferential portion 11 of the first conductor 10, that is, at the heating end point F of the groove 31. At the same time before or after the take-out, the energization to the first conductor 10 is stopped.

  By the above procedure, only the portion X1 shown in FIG. 3A, for example, of the groove 31 of the workpiece 30 can be quenched. Further, by adjusting the energization time only in a certain state among the state in which the protruding portion 21 is inserted in the groove portion 31, heat treatment is performed on a part rather than the entire length of the groove portion 31 and the back surface portion 38 of the work 30. Can do.

  As described above, the chuck mechanism may be moved downward to lower the workpiece 30, and the chuck mechanism may be moved upward to raise the workpiece 30. You may move along the direction.

  As the work 30, a steel material in which V grooves are formed in the longitudinal direction except for both end portions 36 and 37 as shown in FIG. As the opening edge portions 35a and 35b of the steel material, as shown in FIG. 3 (b), those slightly swelled compared with those shown in FIG. 3 (c) were used. Quenching was performed by the following procedure using the induction heating method described above. While moving the workpiece 30, first, the lower end of the groove 31 passes through the other circulating portion 12, and then the protruding portion 21 is inserted into the groove 31 to pass a high-frequency current through the first conductor 10, and then the upper end of the groove 31. Energization was stopped before passing through one of the circulating portions 11, and the protruding portion 21 was taken out from the groove portion 31. At that time, thermocouples were arranged at portions indicated by reference signs A, B, and C in FIG. Reference numeral A is the groove bottom 33, reference numeral B is the opening edge 35 b, and reference numeral C is the back surface 38.

(Comparative example)
As a comparative example, in the example, the second conductor 20 was not used and the first conductor 10 was used for quenching.

  FIG. 5A is a diagram showing the results of the example, and FIG. 5B is a diagram showing the results of the comparative example. In either case, the vertical axis represents temperature (° C.), and the horizontal axis represents time. In the embodiment, as shown in FIG. 5A, the part B and the part C of the work 30 draw substantially the same temperature profile, and the temperature difference from the part A is about 200 ° C. On the other hand, in the comparative example, there is a temperature difference between the part B and the part C of the workpiece 30 as shown in FIG. Moreover, the temperature difference between the part B and the part C is about 275 ° C. Therefore, comparing the example and the comparative example, it was found that the temperature difference between the part B and the part C was smaller when the second conductor 20 was taken in and out.

The induction heating coil according to the embodiment of the present invention can be changed as appropriate according to the shape of the groove 31 of the workpiece 30 as well as the configuration shown in FIGS. In the following, the reference numerals shown for convenience will be described together.
The groove portion 31 of the workpiece 30 is not limited to a V-shaped cross section, and may be recessed such as a substantially concave shape or a substantially U shape. The shape of the protruding portion 21 of the induction heating coil 1 is a depression. It may be along the shape.
Furthermore, if the cross-sectional shape of the groove portion of the workpiece is asymmetric, the protruding portion 21 may be asymmetrical corresponding to the shape of the groove portion 31 of the workpiece 30, and in that case, each surface of the groove portion 31 and the outer peripheral surface of the protruding portion 21. Is preferably a shape that maintains a certain distance.
The bending portion 22 does not need to be an arcuate arc portion as shown in FIG. 1, and may be any one that surrounds the workpiece 30 in an annular shape by the protruding portion 21 and the connecting portion 23.

The induction heating method and the induction heating method according to the embodiment of the present invention are not limited to the work 30 shown in FIG. 3, and the groove 31 may be formed over the entire length of the work 30, and the depth of the groove 31 is axial. It may change along. In this case, what is necessary is just to adjust the site | part in which the protrusion part 21 of the induction heating coil 1 is inserted in the groove part 31 of the workpiece | work 30. FIG.
Furthermore, the shape along the axial direction of the workpiece 30 does not have to be linear, and may have a shape in which only both end portions are bent according to the use of the workpiece 30. In this case, the induction heating coil 1 may be moved by the moving mechanism in at least two directions on the surface having the normal direction as the axial direction.

1: induction heating coil 10: first conductor 11, 12: rotating portion 13, 15: lead portion 14: connecting portion 16a, 16b: support portion 20: second conductors 21, 21a, 21b: projecting portions 22, 22a, 22b : Curved portions 23, 23a, 23b: connecting portion 24: partition members 25a, 25b: pipe connecting portion
26: Insulating sheet material 31, g: Groove portions 32a, 32b: Inner portion 33: Groove bottom portions 34a, 34b: Outer portions 35a, 35b: Opening edge portion 36: One end portion 37: Workpiece other end portion 38: Back portion

Claims (7)

An induction heating coil for heating a workpiece in which a groove is provided along a longitudinal axis,
A first conductor in which a circulating portion that circulates the workpiece around the workpiece axis is coaxially disposed at an interval, and the circulating portions are connected to each other;
A second conductor that has a protrusion so as to face the groove of the workpiece, and that is arranged between the surrounding portions and through which an induced current flows due to a current that flows through the surrounding portion,
An induction heating coil comprising:   The second conductor is disposed toward the opening of the groove portion of the workpiece, the protruding portion having a shape along the cross-sectional shape of the groove portion of the workpiece, and a curved portion disposed along the circumferential portion of the first conductor. The induction heating coil according to claim 1, further comprising: a connecting portion that connects the protruding portion and the bending portion. The curved portion of the second conductor has a larger curvature than the circular portion of the first conductor;
The induction heating coil according to claim 2, wherein the curved portion of the second conductor is disposed on the inner side of the circumferential portion of the first conductor in a state where the protruding portion is inserted into the groove portion of the workpiece. When heating a workpiece in which the groove is provided along the longitudinal axis,
An induction heating method, wherein the work is inserted through the induction heating coil according to claim 1, and any one of the induction heating coil and the work is moved along an axial direction of the work.   The induction heating method according to claim 4, wherein either the second conductor or the workpiece is moved so that a gap between the protruding portion of the second conductor and the groove portion of the workpiece is within a certain range.   The induction heating method according to claim 4 or 5, wherein a gap between the projecting portion of the second conductor and the groove portion of the workpiece is changed according to the depth of the groove portion of the workpiece.   The protruding portion of the second conductor is inserted into the heating start point of the work groove portion, and the second conductor is relatively moved to the heating end point of the work groove portion, and at the heating end point, the protruding portion of the second conductor is moved to the work groove portion. The induction heating method according to claim 4, wherein the induction heating method is drawn out from the groove.

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