Mobile quenching apparatus

Abstract

This mobile quenching device performs mobile quenching on a shaft body in which a large-diameter part having a relatively large outside diameter and a small-diameter part having a relatively small outside diameter adjoin each other across a step part, the mobile quenching device comprising a plurality of split coils that are disposed in a ring shape around a center axis and that channel a high-frequency current, and a coil drive unit for moving each of the split coils towards and away from the center axis. Each of the split coils is provided with a plurality of convex coil parts shaped so as to be convex away from the center axis when viewed along the center axis. The convex coil parts are disposed so as to at least partially overlap in the direction in which the center axis extends, and so as to overlap in the radial direction centered on the center axis when viewed along the center axis.

Description

Technical Field

[0001] The present disclosure relates to a traveling quenching device.

Background Art

[0002] Conventionally, induction heating has been used to perform traveling quenching on a shaft-like body to increase the fatigue strength of the shaft-like body. Here, traveling quenching means quenching while moving a coil member or the like in the axial direction with respect to the shaft-like body. Specifically, the shaft-like body is induction-heated by flowing an electric current through a coil while moving the coil along the outer peripheral surface in the longitudinal direction of the shaft-like body. Then, the shaft-like body is rapidly cooled and quenched by spraying a coolant onto the outer peripheral surface immediately after heating. Here, when the shaft-like body is a stepped shaft having a stepped portion where the outer diameter changes from a large diameter to a small diameter or from a small diameter to a large diameter at an intermediate position in its longitudinal direction, in order to maintain the heating efficiency, it is necessary to appropriately adjust the air gap between the outer peripheral surface of the shaft-like body and the coil.

[0003] One device configuration that enables such adjustment is a form in which the coil is composed of a plurality of divided coils. Specifically, a plurality of divided coils are arranged side by side in the circumferential direction of the shaft-like body, and these divided coils are connected in series to a power source. Then, while flowing an electric current from the power source through each divided coil, these divided coils are moved in the longitudinal direction of the shaft-like body. Then, immediately before the divided coil reaches the stepped portion, the air gap is maintained substantially constant by approaching or separating each divided coil with respect to the outer peripheral surface of the shaft-like body according to the change in the outer diameter dimension of the shaft-like body.

[0004] A conventional high-frequency induction heating device using this type of divided coil is disclosed in Patent Document 1 below. The device is equipped with a high-frequency induction heating coil as a divided coil. This high-frequency induction heating coil for heating an axial member employs a configuration in which, "a axial member having a flange portion and a shaft portion erected at the center of the flange portion, the coil for heating an arc portion formed between the intersecting flange portion and the shaft portion and the outer circumferential surface of the shaft portion by high-frequency induction heating, the coil comprises a pair of high-frequency induction heating coil components arranged at positions opposite to each other across the axis of the axial member, and positioned at a distance from the arc portion and the shaft portion of the axial member, and each of the pair of high-frequency induction heating coil components has a bent coil portion formed so as to protrude in a direction away from the axis of the axial member." According to the device, "By using a pair of high-frequency induction heating coil components, it becomes possible to arrange the aforementioned pair of high-frequency induction heating coil components in correspondence with all types of axial members having different outer diameters." [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2008-150640 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, conventional mobile hardening apparatuses, including the above-mentioned apparatus, have a single turn in their segmented coil, and due to structural reasons, it was not possible to increase the number of turns to multiple. This is because if multiple segmented coils were stacked along the longitudinal direction of the shaft to increase the number of turns, it would be impossible to properly perform mobile hardening on the stepped section where the outer diameter of the shaft changes. For example, in mobile hardening of a stepped section moving from a large diameter section to a small diameter section, the segmented coil cannot be brought close to the small diameter section until the entire segmented coil, which overlaps along the longitudinal direction of the shaft, has passed the large diameter section. Therefore, the portion of the segmented coil that has finished heating the large diameter section and reached the small diameter section, and is located on the forward side in the direction of travel, is induction heated with a wide air gap between it and the outer surface of the small diameter section, which is undesirable from the viewpoint of heating efficiency and uneven hardening.

[0007] On the other hand, in the moving hardening of a stepped section from a small diameter section to a large diameter section, the rearward portion of the divided coils overlapping in the longitudinal direction of the shaft body must be moved away from the outer surface of the small diameter section early on, even if the small diameter section is still being heated, before the forward portion reaches the large diameter section, otherwise it will not be able to overcome the stepped section. Therefore, this also results in undesirable results from the viewpoint of heating efficiency and uneven hardening.

[0008] For the reasons explained above, conventional split coils could not have multiple turns and were typically configured with a single turn. In the case of a single turn, the current flowing through the split coil had to be significantly higher than in the case of multiple turns, which made it prone to problems such as overheating and short circuits in the split coil.

[0009] This disclosure has been made in view of the above circumstances and aims to provide a mobile hardening apparatus that can perform mobile hardening of a stepped shaft while suppressing overheating and short circuits of the segmented coils caused by high currents. [Means for solving the problem]

[0010] To address the above issues, this disclosure proposes the following embodiments. (1) A mobile quenching apparatus according to one aspect of the present disclosure is A device for performing mobile quenching on a shaft-shaped body having a large-diameter section with a relatively large outer diameter and a small-diameter section with a relatively small outer diameter connected by a stepped section, Multiple segmented coils arranged in a ring around a central axis through which high-frequency current flows, A coil drive unit that moves each of the divided coils closer to and further away from the central axis, Equipped with, Each of the aforementioned divided coils comprises a plurality of convex coil portions having a shape that is convex in a direction away from the central axis when viewed along the central axis; Each of the aforementioned convex coil portions, In the direction of extension of the aforementioned central axis, at least a portion of them overlap with each other and, In the line of sight along the aforementioned central axis, the lines of sight overlap in the radial direction centered on the aforementioned central axis. They are arranged in this manner.

[0011] According to the mobile quenching apparatus described in (1) above, when multiple segmented coils are arranged around the shaft and a high-frequency current is supplied to each segmented coil, the high-frequency current flows through each of the multiple convex coil sections, which are arranged so that at least a portion of them overlap in the direction extending along the central axis and overlap radially with respect to the line of sight along the central axis. As a result, the shaft is heated by electromagnetic induction between each convex coil section and the shaft. Then, when moving each segmented coil along the longitudinal direction of the axial body, if it is moving from the small diameter section to the large diameter section and crosses a step, the coil drive unit separates each segmented coil from the outer surface of the small diameter section, so that all the convex coil sections can be simultaneously positioned at a location corresponding to the outer surface of the large diameter section. Then, the large diameter section is subjected to moving hardening after the small diameter section. On the other hand, when moving from the large-diameter section to the small-diameter section and overcoming the step, after each convex coil section passes the position of the large-diameter section, the coil drive unit brings each segmented coil closer to the outer surface of the small-diameter section, so that all convex coil sections can be simultaneously positioned at the position corresponding to the outer surface of the small-diameter section. Then, the small-diameter section is subjected to moving hardening following the large-diameter section. In all of the above cases, each convex coil section is arranged so that at least a portion of it overlaps with the others in the direction extending along the central axis, and that in the line of sight along the central axis it overlaps in the radial direction centered on the central axis. Therefore, in the direction of movement, the positions of all convex coil sections in the direction extending along the central axis always coincide. Thus, the overall thickness of each convex coil section can be made thinner than when they are stacked in the direction of the central axis, thus eliminating the problems that arise when each convex coil section is stacked in the direction of the central axis. In this way, since movable hardening can be performed with multiple-turn divided coils, the current value of the high-frequency current flowing through each divided coil can be significantly reduced compared to the case of a single turn.

[0012] (2) In the mobile quenching apparatus described in (1) above, the following configuration may be adopted: Each of the aforementioned divided coils is A connecting portion that electrically connects each of the aforementioned convex coil portions, A first conductor portion is electrically connected to one end of each of the convex coil portions around the central axis and extends in the radial direction, A second conductor portion is electrically connected to the other end of each of the convex coil portions around the central axis and extends in the radial direction, Furthermore, The first conductor section and the second conductor section are arranged to overlap with respect to the connection section in the direction of the central axis.

[0013] According to the mobile quenching apparatus described in (2) above, by overlapping the first and second wire sections, which do not contribute to induction heating, with the original connection section in a direction along the central axis, the portion of the shaft that is not induced heated in the circumferential direction can be reduced. In other words, if the first and second wire sections were to be placed in the gaps between each divided coil, it would be necessary to expand the unheated area between these divided coils. However, by placing the first and second wire sections in positions other than the gaps between each divided coil, the gaps between each divided coil can be narrowed. Therefore, uneven heating in the circumferential direction of the shaft can be suppressed, and uniform heating can be achieved.

[0014] (3) In the moving quenching device described in (2) above, the following configuration may be adopted: Each of the divided coils is a two-layer coil having an inner peripheral convex coil portion relatively close to the central axis and an outer peripheral convex coil portion relatively far from the central axis as the respective convex coil portions; The first lead portion has a first bent portion that bends in a direction toward the central axis side from the position of the outer peripheral convex coil portion and is connected to the one end side of the inner peripheral convex coil portion; The second lead portion has a second bent portion that bends from the other end side toward the one end side, and a third bent portion that bends from the second bent portion and is connected to the other end side of the outer peripheral convex coil portion.

[0015] According to the moving quenching device described in (3) above, the first lead portion can be connected to the inner peripheral convex coil portion so as to bypass the outer peripheral convex coil portion by the first bent portion. Also, the second lead portion can be connected to the outer peripheral convex coil portion so as to bypass the connection portion by the combination of the second bent portion and the third bent portion. Therefore, the first lead portion and the second lead portion can be overlapped on the connection portion without interfering with other parts.

[0016] (4) In the moving quenching device described in (2) above, the following configuration may be adopted: Each of the divided coils is a three-layer coil having a first convex coil portion, a second convex coil portion, and a third convex coil portion arranged in order in a direction away from the central axis as the respective convex coil portions; The first lead portion and the second lead portion overlap in a direction along the central axis with respect to the connection portion connecting between the first convex coil portion and the second convex coil portion and the connection portion connecting between the second convex coil portion and the third convex coil portion.

[0017] According to the moving quenching device described in (4) above, since the first conductor part and the second conductor part do not enter the gaps between the respective divided coils adjacent to each other, the interval between the respective divided coils can be narrowed. Therefore, uneven heating in the circumferential direction of the shaft body can be suppressed and uniform heating can be performed. Moreover, by using a three-layer coil, the current value of the high-frequency current flowing through each divided coil can be further reduced.

[0018] (5) In the moving quenching device described in (1) above, the following configuration may be adopted: Each of the divided coils is a three-layer coil having, as the respective convex coil parts, a first convex coil part, a second convex coil part, and a third convex coil part arranged in order in a direction away from the central axis; Each of the divided coils a first connection part connecting between the first convex coil part and the second convex coil part, a second connection part connecting between the second convex coil part and the third convex coil part, a first conductor part electrically connected to the first convex coil part and extending in the radial direction, a second conductor part electrically connected to the third convex coil part and extending in the radial direction, and comprising; at least a part of the first conductor part and the second conductor part is displaced in the circumferential direction with respect to the first connection part and the second connection part about the central axis.

[0019] According to the moving quenching device described in (5) above, since at least a part of the first conductor part and the second conductor part is displaced in the circumferential direction with respect to the first connection part and the second connection part, the arrangement interval between the first connection part and the second connection part in the direction along the central axis can be narrowed. Therefore, the thickness of the entire divided coil can be reduced, and problems regarding interference between each divided coil and the stepped part when passing through the stepped part while moving and heating the shaft body are less likely to occur. Moreover, by using a three-layer coil, the current value of the high-frequency current flowing through each divided coil can be further reduced.

[0020] (6) In the mobile quenching apparatus described in any one of the above items (1) to (3), the number of each divided coil may be two or three.

[0021] According to the mobile quenching apparatus described in (6) above, the number of regions that do not contribute to induction heating, formed between adjacent segmented coils, can be minimized. Therefore, uneven heating in the circumferential direction of the axial body can be suppressed, and uniform heating can be more reliably achieved. [Effects of the Invention]

[0022] According to the mobile hardening apparatus described in each of the above embodiments, a stepped shaft can be hardened while suppressing overheating and short circuits of the segmented coils caused by high currents. [Brief explanation of the drawing]

[0023] [Figure 1] This is a schematic side view showing a part of a mobile quenching apparatus according to the first embodiment of the present disclosure, with a fractured section. [Figure 2] This is a perspective view of one of the segmented coils in the mobile hardening apparatus, viewed from below. The opening angle between the first and second wire sections is 180°, but in this figure, for illustrative purposes, the opening angle is shown narrowed using a broken line. [Figure 3] This figure shows the state in which the small diameter portion of the shaft-shaped body is being inductively heated by the split coil, and is a view taken along arrow AA in Figure 1. [Figure 4] This figure shows the state in which the divided coil reaches the position of the BB cross section in Figure 1 and is inductively heating the large diameter portion of the shaft. [Figure 5] This is a flowchart showing the mobile quenching method in the same embodiment. [Figure 6] This figure shows the state in which a small-diameter portion of a shaft is being induction heated by a mobile quenching apparatus according to a second embodiment of the present disclosure, and is a view taken along the arrow AA in Figure 1. [Figure 7]This figure shows one of the segmented coils of a mobile quenching apparatus according to the third embodiment of the present disclosure, viewed from below. (a) is a perspective view showing the external appearance of the segmented coil, and (b) is a perspective view showing the flow of coolant and current. The opening angle between the first and second conductor sections is 180°, but in this figure, for illustrative purposes, the opening angle is shown narrowed using a broken line. [Figure 8] This figure shows one of the segmented coils of a mobile quenching apparatus according to the fourth embodiment of the present disclosure, viewed from below. (a) is a perspective view showing the external appearance of the segmented coil, and (b) is a perspective view showing the flow of coolant and current. The opening angle between the first and second conductor sections is 180°, but in this figure, for illustrative purposes, the opening angle is shown narrowed using a broken line. [Figure 9] This figure shows the simulation results of a mobile quenching apparatus, and is a longitudinal cross-sectional view of section C in Figure 1. (a) shows a conventional example, and (b) shows an embodiment. [Modes for carrying out the invention]

[0024] Hereinafter, an embodiment of the mobile quenching apparatus according to this disclosure will be described based on the drawings. In the following description, the upper part of the paper along the central axis CL shown in Figure 1 may be referred to as "up" or "upward direction," the lower part of the paper may be referred to as "down" or "downward direction," and the vertical direction of the paper may be collectively referred to as the "longitudinal direction." In addition, the radial direction of the axial body W centered on the central axis CL may be simply referred to as the "radial direction," and the circumferential direction of the axial body W may be referred to as the "circumferential direction."

[0025] [First Embodiment] <Mobile hardening equipment> First, the configuration of the mobile quenching apparatus of this first embodiment will be explained using Figures 1 to 4. Here, Figure 1 is a schematic side view showing a part of the mobile quenching apparatus in a cutaway. Figure 2 is a perspective view of one of the segmented coils provided in the mobile quenching apparatus, viewed from below. Figure 3 is a diagram showing the state in which the small diameter portion of the shaft is being induction heated by the segmented coil, and is a view taken along arrow AA in Figure 1. Figure 4 is a diagram showing the state in which the segmented coil has reached the position of cross-section BB in Figure 1 and is induction heating the large diameter portion of the shaft.

[0026] The traverse hardening apparatus 1 shown in Figure 1 is a device that performs traverse hardening on axles for railway vehicles or shaft-shaped bodies W such as ball screws using high-frequency current. First, let's describe the shaft W. The shaft W is a stepped shaft in which a large diameter section W1, a stepped section W2, a small diameter section W3, a stepped section W4, and a large diameter section W5 are coaxially arranged in this order from bottom to top along its longitudinal direction. The large diameter sections W1 and W5 are cylinders with a circular cross-section and have the largest outer diameter of the entire shaft W. The small diameter section W3 is a cylinder with a circular cross-section and has a smaller outer diameter than the large diameter sections W1 and W5. The stepped section W2 has a frustoconical shape connecting the upper end of the large diameter section W1 and the lower end of the small diameter section W3. The outer diameter of the stepped section W2 gradually decreases upward from the same outer diameter as the large diameter section W1, and then becomes equal to the outer diameter of the lower end of the small diameter section W3. The stepped section W4 has an inverted frustoconical shape connecting the upper end of the small diameter section W3 and the lower end of the large diameter section W5. The outer diameter of the stepped section W4 gradually increases upward from the same outer diameter as the upper end of the small-diameter section W3, and then becomes equal to the outer diameter of the lower end of the large-diameter section W5. The large-diameter section W1, stepped section W2, small-diameter section W3, stepped section W4, and large-diameter section W5 share a central axis CL. If the outer diameter dimensions of the large-diameter sections W1 and W5 are set to 100%, the outer diameter dimension of the small-diameter section W3 is, for example, 80% to 90%. The axial body W is formed from a conductive material, such as carbon steel or low-alloy steel containing 95% or more by weight of iron (Fe), which is the ferrite phase.

[0027] As shown in Figure 1, the mobile quenching apparatus comprises a support unit 10, an induction heating unit 20, a cooling unit 30, a mobile unit 40, a control unit 50, and a power supply 60.

[0028] As shown in Figure 1, the support section 10 includes a lower center 11 and an upper center 12. The lower center 11 coaxially supports the large-diameter portion W1 of the shaft-like body W from below. The upper center 12 coaxially supports the large-diameter portion W5 of the shaft-like body W from above. The lower center 11 and the upper center 12 support the shaft-like body W such that its central axis CL is along the vertical direction and one end of the shaft-like body W (the side with the large-diameter portion W1) is below and the other end (the side with the large-diameter portion W5) is above. The shaft-like body W is rotatably positioned between the lower center 11 and the upper center 12 about the central axis CL. When the lower center 11 and the upper center 12, which support the shaft-like body W in this way, receive a driving force from a shaft-like body rotation motor (not shown) provided in the support section 10, they rotate the shaft-like body W about the central axis CL.

[0029] As shown in Figure 1, the induction heating unit 20 has a plurality of segmented coils 21 and a coil support base 28. In this embodiment, two split coils 21 are employed. Since these two split coils 21 have the same configuration, one of them will be explained with reference to Figure 2, and the other will be omitted from the explanation as it is assumed to have the same configuration. As shown in Figure 2, the divided coil 21 has a convex coil portion 22, a connecting portion 23, a first conductor portion 24, and a second conductor portion 25.

[0030] As shown in Figures 2 and 3, the convex coil portion 22 is a two-turn coil having an inner convex coil portion 22a located relatively close to the central axis CL and an outer convex coil portion 22b located relatively far from the central axis CL. Both the inner convex coil portion 22a and the outer convex coil portion 22b have an arc shape that is convex in the direction away from the central axis CL when viewed along the central axis CL. Alternatively, an L-shape or V-shape may be used instead of this arc shape.

[0031] As shown in Figure 1, the inner circumferential convex coil portion 22a and the outer circumferential convex coil portion 22b are positioned at the same location relative to each other in the direction of extension of the central axis CL. That is, in the direction of extension, the upper surfaces of the inner circumferential convex coil portion 22a and the outer circumferential convex coil portion 22b are at the same location relative to each other, and the lower surfaces are also at the same location relative to each other. The relative positions of the inner circumferential convex coil portion 22a and the outer circumferential convex coil portion 22b in the direction of extension may be perfectly aligned as in this embodiment, or there may be some misalignment. However, from the viewpoint of heating efficiency, it is preferable to have them perfectly aligned as shown in Figure 1. On the other hand, as shown in Figure 3, when viewed from a line of sight along the central axis CL, the inner circumferential convex coil portion 22a and the outer circumferential convex coil portion 22b are arranged overlapping with a gap g1 between them in the radial direction centered on the central axis CL. That is, the inner circumferential convex coil portion 22a and the outer circumferential convex coil portion 22b are at the same position on one end in the circumferential direction. Similarly, the inner circumferential convex coil portion 22a and the outer circumferential convex coil portion 22b are at the same position on the other end in the circumferential direction. These inner circumferential convex coil portion 22a and the outer circumferential convex coil portion 22b cover a range of approximately 180° on the outer circumferential surface of the axial body W, and this range is inductively heated.

[0032] On the other hand, as shown in Figure 1, in the longitudinal direction along the central axis CL, the vertical positions of the inner convex coil portion 22a and the outer convex coil portion 22b coincide. That is, the upper surface of the inner convex coil portion 22a and the upper surface of the outer convex coil portion 22b are at the same position in the longitudinal direction along the central axis CL. Similarly, the lower surface of the inner convex coil portion 22a and the lower surface of the outer convex coil portion 22b are at the same position in the longitudinal direction along the central axis CL.

[0033] The connecting portion 23 electrically and mechanically connects the inner circumferential convex coil portion 22a and the outer circumferential convex coil portion 22b. That is, if one end of the inner circumferential convex coil portion 22a and the outer circumferential convex coil portion 22b is considered the one end and the other the other end, the connecting portion connects the other end of the inner circumferential convex coil portion 22a to the one end of the outer circumferential convex coil portion 22b.

[0034] To explain in more detail using the divided coil 21 on the right side of Figure 3, the connecting section 23 comprises straight sections 23a and 23b and a rewinding section 23c. The straight section 23a is connected to the inner circumferential convex coil section 22a at the upper end of the paper, which is the other end, and extends straight outwards in the radial direction. The straight section 23b is connected to the outer circumferential convex coil section 22b at the lower end of the paper, which is the one end, and extends straight outwards in the radial direction.

[0035] The rewind section 23c has a shape that is convex in the direction away from the central axis CL when viewed along the central axis CL, and connects the ends of the straight sections 23a and 23b. The rewind section 23c has an arc shape that shares the central axis CL with the inner convex coil section 22a and the outer convex coil section 22b. The position of the rewind section 23c in the direction along the central axis CL is the same as that of the inner convex coil section 22a and the outer convex coil section 22b. The unwinding section 23c is positioned with a gap g2 between it and the outer surface of the outer convex coil section 22b. The gap g2 is significantly wider than the gap g1. The unwinding section 23c is the part that returns the current flow in order to make the direction of flow of the high-frequency current between the inner convex coil section 22a and the outer convex coil section 22b the same. In other words, induction heating is performed by the high-frequency current flowing through the inner convex coil section 22a and the outer convex coil section 22b.

[0036] As shown in Figures 2 and 3, the first conductor portion 24 is electrically and mechanically connected to the inner circumferential convex coil portion 22a at the lower end of the paper, which is one end, and extends straight outwards in the radial direction. The first conductor portion 24 is positioned above the straight portion 23b. That is, when viewed in plan along the central axis CL, the first conductor portion 24 is directly below the straight portion 23b. Therefore, compared to the case in Figure 3 where the first conductor portion 24 is interposed between, for example, the straight portion 23b of one of the pair of divided coils 21 and the straight portion 23a of the other, the gap between these divided coils 21 can be narrowed.

[0037] In the straight sections 23a, 23b and the gaps between them, the axial body W cannot be induced heated. Therefore, by not arranging the first conductor section 24 in the gaps as in this embodiment, the unheated area in the circumferential direction of the axial body W can be narrowed, thereby suppressing uneven hardening.

[0038] As shown in Figure 2, the first conductor portion 24 has a first bent portion 24a that curves toward the central axis CL from the position of the outer convex coil portion 22b and connects to one end of the inner convex coil portion 22a. That is, the first conductor portion 24 passes directly below the outer convex coil portion 22b and then bends perpendicularly upward at the first bent portion 24a, connecting to the inner convex coil portion 22a directly below. In this way, the first bent portion 24a allows the first conductor portion 24 to be connected to the inner convex coil portion 22a without interfering with the outer convex coil portion 22b by bypassing it.

[0039] As shown in Figure 2, the second conductor section 25 has a second bend 25a that bends from the other end toward the one end, and a third bend 25b that bends from the second bend 25a toward the other end of the outer convex coil section 22b and connects to it. That is, at the second bend 25a, the second conductor section 25 bends horizontally from below the straight section 23a toward a position below the outer convex coil section 22b. Subsequently, at the third bend 25b, the second conductor section 25 bends upward toward the lower surface of the outer convex coil section 22b and connects to it. In this way, the second bend 25a and the third bend 25b allow the second conductor section 25 to be connected to the outer convex coil section 22b without interfering with the straight section 23a.

[0040] As shown in Figure 3, the second conductor section 25 is electrically and mechanically connected to the outer convex coil section 22b at the upper end of the paper, which is the other end, and extends straight outwards in the radial direction. The second conductor section 25 is positioned above the straight section 23a. That is, when viewed in plan along the central axis CL, the second conductor section 25 is directly below the straight section 23a. Therefore, compared to the case in Figure 3 where the second conductor section 25 is interposed between the straight section 23a of one of the divided coils 21 and the straight section 23b of the other, the gap between each divided coil 21 can be narrowed. As a result, for the reasons described above, the unheated area in the circumferential direction of the axial body W can be narrowed, and uneven hardening can be suppressed.

[0041] Each of the segmented coils 21 described above is manufactured by bending and brazing a hollow tube with a square cross-section, and is electrically conductive. The ends of the first conductor section 24 and the second conductor section 25 are electrically and mechanically connected to the current transformer 61 of the power supply 60 shown in Figure 1. The current transformer 61 supplies high-frequency current to each segmented coil 21. Furthermore, each segmented coil 21 can be cooled by circulating a cooling liquid through its tube.

[0042] Returning to Figure 1, the coil support base 28 supports a pair of segmented coils 21 coaxially with the axial body W. The coil support base 28 includes a guide section (not shown) that guides the pair of segmented coils 21 to move closer to and further apart from each other, and a coil drive section (not shown) that moves these segmented coils 21 closer to and further apart from the central axis CL. For example, a linear guide can be used as the guide section, and a combination of a stepping motor and a ball screw can be used as the coil drive section. The coil support base 28 is connected to and supported by the movable section 40, which will be described later, via a stay 28a.

[0043] As shown in Figure 1, the cooling unit 30 comprises a cooling ring 31, a cooling ring support stay 32, and a coolant circulation pump 33. The cooling ring 31 is formed in an annular shape. An internal space 31a is formed inside the cooling ring 31. Multiple nozzles 31b communicating with the internal space 31a are formed on the inner circumferential surface of the cooling ring 31, spaced apart from each other in the circumferential direction. An axial body W is inserted coaxially into the cooling ring 31. The cooling ring 31 is positioned below each of the segmented coils 21. The cooling ring 31 is connected to and supported by a coolant circulation pump 33 via a cooling ring support stay 32. The coolant circulation pump 33 supplies a coolant L, such as water, into the internal space 31a of the cooling ring 31. The coolant L supplied to the internal space 31a is ejected towards the axial body W through a plurality of nozzles 31b, cooling the axial body W.

[0044] The movable part 40 shown in Figure 1 includes a support plate 41, a pinion gear 42, a motor 43, and a rack 44. The coil support base 28, current transformer 61, cooling ring 31, and coolant circulation pump 33 are fixed to the support plate 41. A pinion gear 42 is rotatably fixed to the support plate 41. A motor 43 that rotates the pinion gear 42 is mounted on the support plate 41.

[0045] The support plate 41 is connected to the rack 44 via a guide rail (not shown). The support plate 41 is movable vertically relative to the rack 44 by the guide rail. The pinion gear 42 meshes with the teeth of the rack 44. Therefore, when the control unit 50 drives the motor 43, the pinion gear 42 rotates, and the support plate 41 moves upward or downward relative to the rack 44.

[0046] The control unit 50 includes an arithmetic circuit (not shown) and a memory. The memory stores a control program for driving the arithmetic circuit and the like. The control unit 50 is connected to the current transformer 61, the coil drive unit, the motor 43, the coolant circulation pump 33, and the axial rotating motor, and controls them.

[0047] For example, when performing movable hardening on the small-diameter portion W3 of the shaft-shaped body W, the control unit 50 controls the coil drive unit to minimize the spacing between the pair of divided coils 21, as shown in Figure 3. On the other hand, when performing movable hardening on the large-diameter portions W1 and W5 of the shaft-shaped body W, the control unit 50 controls the coil drive unit to maximize the gap between the pair of divided coils 21, as shown in Figure 4. Furthermore, when performing movable hardening of the stepped portions W2 and W4 of the axial body W, the control unit 50 controls the coil drive unit to open and close the pair of divided coils 21 in accordance with the change in diameter of the stepped portions W2 and W4 in the longitudinal direction along the central axis CL.

[0048] <Mobile quenching method> Next, the mobile quenching method of this embodiment will be described. Figure 5 is a flowchart showing the mobile quenching method in this embodiment. Prior to this, the axial body W is supported by the support portion 10 so that its central axis CL is aligned in the vertical direction.

[0049] First, in the arrangement step S1, the control unit 50 drives the motor 43 to position the pair of split coils 21 below the large-diameter section W5. Then, the control unit 50 controls the axial body rotation motor to rotate the axial body W around the central axis CL. Next, the control unit 50 drives the current transformer 61 to supply high-frequency current to each of the segmented coils 21. Furthermore, the control unit 50 drives the coolant circulation pump 33 to eject coolant L from multiple nozzles 31b of the cooling ring 31 toward the axial body W. Finally, the control unit 50 controls the coil drive unit to open the gap between a pair of segmented coils 21 to match the outer diameter of the large-diameter section W5. Once the placement process S1 is completed, the process moves on to the first quenching process S2.

[0050] In the subsequent first hardening process S2, the control unit 50 drives the motor 43 to move each segmented coil 21 and the cooling ring 31 together upward. At this time, the large-diameter section W5 between the two segmented coils 21 is inductively heated from its lower end to its upper end. As shown by the black arrow in Figure 4, the high-frequency current at this time first flows from the first conductor section 24 to the inner convex coil section 22a, then through the connection section 23 to the outer convex coil section 22b, and finally to the second conductor section 25. The coolant, shown by the white arrow in Figure 4, also flows in the same way as the high-frequency current, cooling each segmented coil 21. Meanwhile, in the large-diameter portion W5 of the shaft-shaped body W, eddy currents flow on its surface due to the high-frequency current flowing through the inner convex coil portion 22a and the outer convex coil portion 22b, and induction heating is performed by these eddy currents. Then, as the cooling ring 31 passes after each segmented coil 21, the cooling liquid L is sprayed onto the outer surface of the heated large-diameter portion W5. This causes the heated large-diameter portion W5 to cool rapidly and harden.

[0051] In the subsequent split coil diameter reduction process S3, the stepped portion W2, which gradually decreases in diameter towards the top, is induction heated. In the first hardening process described above, the distance between each split coil 21 was kept constant, but in this split coil diameter reduction process, the distance between each split coil 21 is gradually narrowed. That is, when induction heating is applied to the stepped portion W2 between the two split coils 21 from its lower end towards its upper end, the control unit 50 controls the coil drive unit to narrow the distance between the two split coils 21 so that the air gap with the stepped portion W2 is kept constant. At this time, in the stepped portion W2 of the shaft-shaped body W, eddy currents flow on its surface due to the high-frequency current flowing through the inner convex coil portion 22a and the outer convex coil portion 22b, and induction heating occurs due to these eddy currents. Furthermore, as the cooling ring 31 passes after each segmented coil 21, the cooling liquid L is sprayed onto the outer surface of the heated stepped portion W2. As a result, the heated stepped portion W2 is rapidly cooled and hardened.

[0052] In the subsequent second hardening process S4, the small-diameter section W3, which has the smallest outer diameter and is constant along the longitudinal direction, is induction heated. In the above-mentioned segmented coil diameter reduction process, the spacing between each segmented coil 21 was gradually narrowed, but in this second hardening process, the spacing between each segmented coil 21 is kept constant to the minimum extent possible. In other words, when the small-diameter portion W3 is inductively heated from its lower end to its upper end between the two divided coils 21, the control unit 50 controls the coil drive unit to maintain a constant distance between the two divided coils 21 so that the air gap with the small-diameter portion W3 remains constant. The arrangement of each divided coil 21 at this time is shown in Figure 3. Meanwhile, in the small-diameter portion W3 of the shaft-shaped body W, eddy currents flow on its surface due to the high-frequency current flowing through the inner convex coil portion 22a and the outer convex coil portion 22b, and induction heating occurs due to these eddy currents. Then, as the cooling ring 31 passes after each segmented coil 21, the cooling liquid L is sprayed onto the outer surface of the heated small-diameter portion W3. This causes the heated small-diameter portion W3 to cool rapidly and harden.

[0053] In the subsequent segmented coil diameter expansion process S5, the stepped section W4, which gradually expands in diameter upwards, is induction heated. In the second hardening process described above, the spacing between each segmented coil 21 was kept constant, but in this segmented coil diameter expansion process, the spacing between each segmented coil 21 is gradually increased. In other words, when the stepped portion W4 between the two divided coils 21 is inductively heated from its lower end to its upper end, the control unit 50 controls the coil drive unit to widen the distance between the two divided coils 21 so that the air gap with the stepped portion W4 is kept constant. Meanwhile, in the stepped portion W4 of the axial body W, eddy currents flow through the inner convex coil portion 22a and the outer convex coil portion 22b due to the high-frequency current, and induction heating occurs due to these eddy currents. Furthermore, as the cooling ring 31 passes after each segmented coil 21, the cooling liquid L is sprayed onto the outer surface of the heated stepped portion W4. This causes the heated stepped portion W4 to cool rapidly and harden.

[0054] In the subsequent third hardening process S6, the large-diameter section W5, which has the largest outer diameter and is constant along the longitudinal direction, is induction heated. In the above-mentioned split coil diameter expansion process, the spacing between each split coil 21 was gradually widened, but in this third hardening process, the spacing between each split coil 21 is kept constant to maximize it. In other words, when the large-diameter section W5 is inductively heated from its lower end to its upper end between the two divided coils 21, the control unit 50 controls the coil drive unit to maintain a constant distance between the two divided coils 21 so that the air gap with the large-diameter section W5 remains constant. The arrangement of each divided coil 21 at this time is shown in Figure 4. Meanwhile, in the large-diameter portion W5 of the shaft-shaped body W, eddy currents flow on its surface due to the high-frequency current flowing through the inner convex coil portion 22a and the outer convex coil portion 22b, and induction heating is performed by these eddy currents. Furthermore, as the cooling ring 31 passes after each segmented coil 21, the cooling liquid L is sprayed onto the outer surface of the heated large-diameter portion W5. This causes the heated large-diameter portion W5 to cool rapidly and harden.

[0055] Through the processes described above, the shaft-shaped body W is hardened along its entire length, and the entire process is completed. In the positioning process S1, the first hardening process S2, the split coil diameter reduction process S3, the second hardening process S4, the split coil diameter expansion process S5, and the third hardening process S6, the upward movement of each split coil 21 and the cooling ring 31 relative to the shaft-shaped body W is continued without stopping while the moving hardening is performed. The shaft-shaped body W, which has undergone movable quenching along its entire length, exhibits increased hardness compared to before the movable quenching process.

[0056] [Second Embodiment] A mobile quenching apparatus according to the second embodiment of this disclosure will be described below with reference to Figure 6. Figure 6 is a diagram showing the state in which the small diameter portion W3 of the shaft W is being induction heated by the mobile quenching apparatus of this embodiment, and is a view taken along arrow AA in Figure 1. In the following, the differences from the first embodiment will be mainly described, and other aspects will be considered the same as in the first embodiment, and redundant explanations will be omitted.

[0057] In the mobile quenching apparatus of this embodiment, as can be seen by comparing it with Figure 3, the shape of each segmented coil 21 differs from that of the first embodiment. That is, in the first embodiment, one segmented coil 21 was configured to induce heating of a 180° circumferential range of the shaft W. In contrast, the present embodiment shown in Figure 6 employs three segmented coils 21A. Each segmented coil 21A has the same configuration as the first embodiment and is substantially similar in configuration to the segmented coil 21 of the first embodiment, but differs in that one segmented coil 21A induces heating of a 120° circumferential range of the shaft W. That is, by arranging the three segmented coils 21A at equal intervals around the shaft W, the entire 360° circumference of the shaft W is induce heated.

[0058] Each divided coil 21A, like the divided coil 21 described above, has a convex coil portion 22, a connecting portion 23, a first conductor portion 24, and a second conductor portion 25.

[0059] As shown in Figure 6, the convex coil portion 22 of this embodiment is also a two-turn coil having an inner convex coil portion 22a located relatively close to the central axis CL and an outer convex coil portion 22b located relatively far from the central axis CL. Both the inner convex coil portion 22a and the outer convex coil portion 22b have an arc shape that is convex in the direction away from the central axis CL when viewed along the central axis CL.

[0060] These inner circumferential convex coil portion 22a and outer circumferential convex coil portion 22b are arranged at the same position relative to each other in the direction of extension of the central axis CL, similar to the first embodiment described above. The relative positions of the inner circumferential convex coil portion 22a and outer circumferential convex coil portion 22b in the extension direction may be slightly misaligned, but from the viewpoint of heating efficiency, it is preferable that they be perfectly aligned as in this embodiment. As shown in Figure 6, when viewed from a line of sight along the central axis CL, the inner convex coil portion 22a and the outer convex coil portion 22b are arranged overlapping with a gap between them in the radial direction centered on the central axis CL.

[0061] When induction heating the shaft W using the mobile quenching apparatus of this embodiment, the three segmented coils 21A are moved and quenched while moving toward and away from the outer surface of the shaft W radially, according to the outer diameter dimensions of the large diameter sections W1 and W5, the small diameter section W3, and the stepped sections W2 and W4, respectively. In this embodiment, three divided coils 21A are used, but it is also possible to increase this to four or more. However, if the number of divisions in the coil is increased too much, the number of parts between each divided coil that do not contribute to heating will increase, so in practice it is preferable to limit it to three divisions. Also, when comparing a three-part coil configuration with a two-part coil configuration, the two-part configuration is more preferable for the same reason.

[0062] [Third Embodiment] A mobile quenching apparatus according to the third embodiment of this disclosure will be described below with reference to Figure 7. Figure 7 is a view of one of the divided coils 21B of the mobile quenching apparatus according to this embodiment, viewed from below. (a) is a perspective view showing the external appearance of the divided coil 21B, and (b) is a perspective view showing the flow of coolant and current. In the following, the differences from the first embodiment will be mainly described, and other aspects will be considered the same as in the first embodiment, and redundant explanations will be omitted.

[0063] In the first embodiment described above, each divided coil 21 was a two-turn coil having two convex coil portions 22a on the inner circumference and 22b on the outer circumference. However, in this embodiment, a three-turn coil is used as shown in Figures 7(a) and 7(b). In other words, the divided coil 21B of this embodiment has three convex coil sections: a first convex coil section 22p, a second convex coil section 22q, and a third convex coil section 22r, which are arranged in order in the direction away from the central axis CL. The positions of these three convex coil sections 22p, 22q, and 22r are the same in the direction along the central axis CL. The relative positions of the first convex coil section 22p, 22q, and 3rd convex coil section 22r in the direction extending along the central axis CL may be slightly misaligned, but from the viewpoint of heating efficiency, it is preferable that they be perfectly aligned as in this embodiment. Furthermore, when viewed from a line of sight along the central axis CL, the first convex coil portion 22p, the second convex coil portion 22q, and the third convex coil portion 22r are arranged overlapping with a gap between them in the radial direction centered on the central axis CL.

[0064] Furthermore, the first convex coil section 22p and the second convex coil section 22q are connected by a connecting section 23p. Similarly, the second convex coil section 22q and the third convex coil section 22r are connected by a connecting section 23q. Furthermore, the first conductor section 24 and the second conductor section 25 each overlap the connection sections 23p and 23q in the direction along the central axis CL (vertical direction on the paper).

[0065] In the mobile hardening apparatus of this embodiment, the first wire section 24 and the second wire section 25 do not enter the gap between adjacent segmented coils 21B, so the spacing between each segmented coil 21B can be narrowed. Therefore, uneven heating in the circumferential direction of the axial body W can be suppressed and uniform heating can be performed. Furthermore, by using a three-turn coil, the current value of the high-frequency current flowing through each segmented coil 21B can be further reduced.

[0066] [Fourth Embodiment] A mobile quenching apparatus according to the fourth embodiment of this disclosure will be described below with reference to Figure 8. Figure 8 is a view of one of the divided coils 21C of the mobile quenching apparatus according to this embodiment, viewed from below. (a) is a perspective view showing the external appearance of the divided coil 21C, and (b) is a perspective view showing the flow of coolant and current. In the following, the differences from the third embodiment will be mainly described, and other aspects will be considered the same as the third embodiment, and redundant explanations will be omitted.

[0067] The split coil 21C of this embodiment is a three-turn coil, similar to the split coil 21B of the third embodiment described above, but the positions of at least a portion of the first conductor portion 24 and the second conductor portion 25 are shifted in the circumferential direction around the central axis CL with respect to the positions of the connection portions 23p and 23q.

[0068] According to the mobile hardening apparatus of this embodiment, the spacing between the connecting portions 23p and 23q in the direction along the central axis CL can be narrowed compared to the divided coil 21B of the third embodiment described above. Therefore, the overall thickness of each divided coil 21C can be reduced, making it less likely for problems related to interference between each divided coil 21C and the stepped portions W2 and W4 to occur when the axial body W is heated while moving and passing through the stepped portions W2 and W4. Furthermore, similar to the third embodiment described above, by using a three-turn coil, the current value of the high-frequency current flowing through each divided coil 21C can be further reduced.

[0069] The main points of each embodiment and modification described above are summarized below. [1] A mobile quenching apparatus according to one aspect of the present disclosure is A device for performing movable hardening on an axial body (W) in which a large-diameter section (W1, W5) with a relatively large outer diameter and a small-diameter section (W3) with a relatively small outer diameter are connected via stepped sections (W2, W4), Multiple segmented coils (21, 21A, 21B, 21C) are arranged in a ring around a central axis (CL) through which high-frequency current flows, A coil drive unit that moves each of the aforementioned segmented coils (21, 21A, 21B, 21C) closer to and further away from the central axis (CL), Equipped with, Each of the aforementioned segmented coils (21, 21A, 21B, 21C) comprises a plurality of convex coil portions (22, 22a, 22b, 22p, 22q, 22r) having a shape that is convex in the direction away from the central axis (CL) when viewed along the central axis (CL); Each of the aforementioned convex coil portions (22, 22a, 22b, 22p, 22q, 22r) In the direction of extension of the central axis (CL), at least a portion of them overlap with each other and, In the line of sight along the aforementioned central axis (CL), the lines of sight overlap in the radial direction centered on the aforementioned central axis (CL). They are arranged in this manner.

[0070] [2] In the mobile quenching apparatus described in [1] above, Each of the aforementioned segmented coils (21, 21A, 21B) A connecting portion (23) electrically connects each of the aforementioned convex coil portions (22, 22a, 22b, 22p, 22q, 22r), A first conductor portion (24) is electrically connected to one end of each of the convex coil portions (22, 22a, 22b, 22p, 22q, 22r) around the central axis (CL) and extends in the radial direction, A second conductor portion (25) is electrically connected to the other end of each of the convex coil portions (22, 22a, 22b, 22p, 22q, 22r) around the central axis (CL) and extends in the radial direction, Furthermore, The first conductor portion (24) and the second conductor portion (25) are arranged to overlap with the connection portion (23) in the direction of the central axis (CL).

[0071] [3] In the mobile quenching apparatus described in [2] above, Each of the divided coils (21) is a two-turn coil having an inner circumferential convex coil portion (22a) that is relatively close to the central axis and an outer circumferential convex coil portion (22b) that is relatively far from the central axis as the respective convex coil portions; The first conductor portion (24) has a first bent portion (24a) that curves in a direction toward the central axis (CL) than the position of the outer circumferential convex coil portion (22b) and connects to one end of the inner circumferential convex coil portion (22a); The second conductor portion (25) has a second bent portion (25a) that bends from the other end toward the one end, and a third bent portion (25b) that bends from the second bent portion (25a) toward the other end of the outer peripheral convex coil portion (22b) and connects to it.

[0072] [4] In the mobile quenching apparatus described in [2] above, Each of the divided coils (21B) is a three-turn coil having a first convex coil section (22p), a second convex coil section (22q), and a third convex coil section (22r) arranged in order away from the central axis (CL), as the respective convex coil sections (22p, 22q, 22r); The first conductor portion (24) and the second conductor portion (25) overlap the connecting portion (23p) that connects the first convex coil portion (22p) and the second convex coil portion (22q), and the connecting portion (23q) that connects the second convex coil portion (22q) and the third convex coil portion (22r), in a direction along the central axis (CL).

[0073] [5] In the mobile quenching apparatus described in [1] above, Each of the aforementioned divided coils (21C) is a three-turn coil having a first convex coil portion (22p), a second convex coil portion (22q), and a third convex coil portion (22r) arranged in order away from the central axis (CL), as the respective convex coil portions (22p, 22q, 22r); Each of the aforementioned divided coils (21C) A first connecting portion (23p) connects the first convex coil portion (22p) and the second convex coil portion (22q), A second connecting portion (23q) connects the second convex coil portion (22q) and the third convex coil portion (22r), A first conductor portion (24) is electrically connected to the first convex coil portion (22p) and extends in the radial direction, A second conductor portion (25) is electrically connected to the third convex coil portion (22r) and extends in the radial direction, Equipped with; At least a portion of the first conductor portion (24) and the second conductor portion (25) is offset in the circumferential direction with respect to the first connection portion (23p) and the second connection portion (23q) with respect to the central axis (CL).

[0074] [6] In the mobile quenching apparatus described in any one of the above items [1] to [5], The number of each of the aforementioned segmented coils (21, 21A, 21B, 21C) is either two or three. [Examples]

[0075] Below, we will describe the simulation results for a comparative example in which induction heating was performed using a mobile quenching apparatus with a conventional single-turn split coil, and for an example in which induction heating was performed using a mobile quenching apparatus with a split coil 21 based on the first embodiment described above. Figure 9 shows the simulation results and is a longitudinal cross-sectional view of section C in Figure 1. (a) shows the conventional example, and (b) shows the embodiment. In this simulation, the outer diameter of the large diameter section W5 was set to 200 mm, and the outer diameter of the small diameter section W3 was set to 170 mm. The material of the shaft W was carbon steel. The current value required to heat to approximately the same temperature was then determined. As a result, the required current value was 45,000 A in the one-turn comparative example and 24,750 A in the two-turn embodiment. Thus, it was confirmed that the current value could be significantly reduced in the embodiment compared to the comparative example. [Industrial applicability]

[0076] According to the mobile hardening apparatus of this disclosure, stepped shafts can be hardened in a mobile manner while suppressing overheating and short circuits of the segmented coils caused by high currents. [Explanation of Symbols]

[0077] 21, 21A, 21B, 21C Split coil 22 Convex coil section 22a Inner circumference convex coil portion 22b Outer circumference convex coil section 22p First convex coil section 22q Second convex coil section 22r Third convex coil section 23 Connection part, 23p Connection section (First connection section) 23q Connection part (second connection part) 24 1st conductor section 24a 1st bending part 25 2nd conductor section 25a 2nd bending part 25b 3rd bending part CL center axis W-shaped axial body W1, W5 Large diameter section W2, W4 Step section W3 Small diameter section

Claims

1. A device for performing mobile quenching on a shaft-shaped body having a large-diameter section with a relatively large outer diameter and a small-diameter section with a relatively small outer diameter connected by a stepped section, Multiple segmented coils arranged in a ring around a central axis through which high-frequency current flows, A coil drive unit that moves each of the divided coils closer to and further away from the central axis, Equipped with, Each of the aforementioned divided coils comprises a plurality of convex coil portions having a shape that is convex in a direction away from the central axis when viewed along the central axis; Each of the aforementioned convex coil portions, In the line of sight along the direction perpendicular to the central axis, at least a portion of them overlap with each other, From a line of sight along the central axis, the objects are arranged with a gap between them in the radial direction centered on the central axis; A mobile quenching apparatus characterized by the following features.

2. Each of the aforementioned divided coils is A connecting portion that electrically connects each of the aforementioned convex coil portions, A first conductor portion is electrically connected to one end of each of the convex coil portions around the central axis and extends in the radial direction, A second conductor portion is electrically connected to the other end of each of the convex coil portions around the central axis and extends in the radial direction, Furthermore, In a line of sight along the central axis, the first conductor section and the second conductor section are arranged to overlap with the connection section. The mobile quenching apparatus according to claim 1.

3. Each of the divided coils is a two-turn coil having an inner convex coil portion relatively close to the central axis and an outer convex coil portion relatively far from the central axis as its respective convex coil portion; The first conductor portion has a first bent portion that curves in a direction toward the central axis than the position of the outer circumferential convex coil portion and connects to one end of the inner circumferential convex coil portion; The second conductor portion has a second bend that curves from the other end toward the one end, and a third bend that curves from the second bend to connect to the other end of the outer convex coil portion; The mobile quenching apparatus according to feature 2.

4. Each of the aforementioned divided coils is a three-turn coil having a first convex coil section, a second convex coil section, and a third convex coil section arranged in order in a direction away from the central axis; The first conductor portion and the second conductor portion are arranged to overlap, in line with respect to the connecting portion that connects the first convex coil portion and the second convex coil portion, and the connecting portion that connects the second convex coil portion and the third convex coil portion, in a line of sight along the central axis; The mobile quenching apparatus according to feature 2.

5. Each of the aforementioned divided coils is a three-turn coil having a first convex coil section, a second convex coil section, and a third convex coil section arranged in order in a direction away from the central axis; Each of the aforementioned divided coils is A first connecting portion connecting the first convex coil portion and the second convex coil portion, A second connecting portion connecting the second convex coil portion and the third convex coil portion, A first conductor portion is electrically connected to the first convex coil portion and extends in the radial direction, A second conductor portion is electrically connected to the third convex coil portion and extends in the radial direction, Equipped with; At least a portion of the first conductor portion and the second conductor portion is offset in the circumferential direction with respect to the first connection portion and the second connection portion, with respect to the central axis; The mobile quenching apparatus according to claim 1.

6. The number of each of the aforementioned segmented coils is two or three. A mobile quenching apparatus according to any one of claims 1 to 5.

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