Mobile quenching method and mobile quenching device

Abstract

Provided is a mobile quenching method in which a mobile quenching device (100) provided with a plurality of high-frequency coils (111) is used, a shaft-shaped body (10) inserted through the inside of the plurality of high-frequency coils (111) is rotated relative to the plurality of high-frequency coils (111), and the plurality of high-frequency coils (111) are moved relative to the shaft-shaped body (10) in the axial direction. Movement quenching is performed while a plurality of heating regions generated on the surface of the shaft-shaped body (10) by the plurality of high-frequency coils (111) are moved, and at least one of the relative movement speed of the plurality of high-frequency coils (111) with respect to the axial direction of the shaft-shaped body (10) and the relative rotation speed of the shaft-shaped body (10) with respect to the plurality of high-frequency coils (111) is changed. The plurality of heating bands passing through the plurality of heating regions overlap or are adjacent to each other.

Description

Technical Field

[0001] The invention relates to a mobile quenching method and a mobile quenching device. Background Art

[0002] Sometimes, various surface treatments are performed on steel parts that require a long life. In particular, high-frequency quenching is widely used because it improves the surface hardness, wear resistance, and fatigue resistance of the parts. Therefore, various high-frequency quenching devices have been proposed in the past. For example, when high-frequency quenching is performed on long parts such as steel shafts, so-called traverse hardening is performed. Traverse hardening is a method of quenching while moving a high-frequency induction heating coil (also called a high-frequency coil) and a cooling device relative to the shaft in the axial direction of the shaft.

[0003] In the mobile quenching, the shaft body is locally heated by a high-frequency coil until at least the surface of the shaft body becomes an austenite phase. Then, a cooling medium such as a coolant is sprayed onto the surface of the heated shaft body by a cooling device following the high-frequency coil, and the shaft body is rapidly cooled in a short time, thereby making the surface of the shaft body a structure having a desired hardness such as a martensite phase.

[0004] The outer diameter of the shaft-shaped body is sometimes not constant in the direction along its axis (also called the axial direction). That is, there is a shaft-shaped body having a small diameter portion with a relatively small outer diameter and a large diameter portion with a relatively large outer diameter in the axial direction of the shaft-shaped body. In addition, these small diameter portions and large diameter portions are connected by a step portion whose outer diameter gradually changes in the axial direction. For example, in the technology disclosed in Patent Document 1 or Patent Document 2, the change in the outer diameter size of the shaft-shaped body is handled by making the split coil advance and retreat in the radial direction of the shaft-shaped body as the heated body.

[0005] However, conventionally, when split coils are used, heating unevenness may occur in the axial and circumferential directions of the shaft-shaped body. The inventors of the present invention have conducted in-depth research and found that when the heating zones of adjacent coils are separated from each other, the separated portions are not quenched, which causes heating unevenness.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: (Japanese) Patent Publication No. 2008-150640

[0009] Patent Document 2: (Japan) Patent Gazette No. Sho 36-10457 Summary of the invention

[0010] Technical problem to be solved by the invention

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a transfer quenching method and a transfer quenching device capable of reducing heating unevenness in the axial direction and the circumferential direction of a shaft-shaped body.

[0012] Technical solutions for solving technical problems

[0013] (1) A mobile quenching method according to one aspect of the present invention uses a mobile quenching device having a plurality of high-frequency coils to quench an axial body, and is characterized in that the axial body inserted into the inner side of the plurality of high-frequency coils is rotated relative to the plurality of high-frequency coils, and the plurality of high-frequency coils are moved relative to the axial body in an axial direction, and mobile quenching is performed while a plurality of heating areas generated on the surface of the axial body by the plurality of high-frequency coils are moved, and at least one of the relative movement speed of the plurality of high-frequency coils relative to the axial body and the relative rotation speed of the axial body relative to the plurality of high-frequency coils is changed so that a plurality of heating zones through which the plurality of heating areas pass overlap or are adjacent to each other.

[0014] (2) In the moving quenching method described in (1), when the relative angular velocity of the shaft-shaped body with respect to the plurality of high-frequency coils is set to ω, the moving velocity is set to vl, the length of the heating region in the axial direction is set to T, the distance between the heating regions adjacent to each other in the circumferential direction of the shaft-shaped body is set to wo, and the radius of the shaft-shaped body where the heating region is located is set to R, the following formula 1 is satisfied:

[0015] (vl / ωR)×wo≦T …Formula 1.

[0016] (3) In the movement quenching method described in (1) or (2), the temperature of the heating zone may be 850° C. or higher.

[0017] (4) A mobile quenching device according to one embodiment of the present invention is a mobile quenching device for quenching an axial body, characterized in that the mobile quenching device includes a plurality of high-frequency coils and a cooling portion in an axial direction, and includes a control portion capable of controlling the movement of the plurality of high-frequency coils and the cooling portion, wherein the control portion causes the axial body inserted into the inner side of the plurality of high-frequency coils to rotate relative to the plurality of high-frequency coils, and causes the high-frequency coil to move relative to the axial body in the axial direction, thereby performing mobile quenching while moving a plurality of heating areas generated on the surface of the axial body by the plurality of high-frequency coils, and the control portion is capable of controlling the quenching device in such a manner as to change at least one of the relative movement speed of the plurality of high-frequency coils relative to the axial body and the relative rotation speed of the axial body relative to the plurality of high-frequency coils, so that the plurality of heating zones through which the plurality of heating areas pass overlap or are adjacent to each other.

[0018] (5) In the mobile quenching device described in (4), it may also be that when the relative angular velocity of the shaft-shaped body with respect to the plurality of high-frequency coils is set to ω, the moving speed is set to vl, the length of the high-frequency coil in the axial direction is set to T', the distance between the high-frequency induction parts of the high-frequency coils adjacent to each other in the circumferential direction of the shaft-shaped body is set to wo', and the radius of the circle inscribed in the plurality of high-frequency coils is set to R', the control unit can control the moving speed and / or the rotation speed in a manner that satisfies the following formula 2:

[0019] (vl / ωR')×wo'≦T' …Formula 2.

[0020] (6) In the moving quenching device described in (4) or (5), the temperature of the heating zone may be 850° C. or higher.

[0021] Effects of the Invention

[0022] According to the transfer quenching method and transfer quenching device of the present invention, it is possible to reduce heating unevenness in the axial direction and the circumferential direction of the shaft-shaped body. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a diagram showing a portion of a mobile quenching device according to an embodiment of the present invention in a broken state, and is a side view schematically showing the mobile quenching device.

[0024] Figure 2 It schematically shows a partial cross section of the shaft-shaped body and a cross-sectional view of two high-frequency coils when viewed in a plan view along the axis of the shaft-shaped body, and is a diagram showing a state in which the high-frequency coil moves in accordance with the outer diameter of the small-diameter portion.

[0025] Figure 3 It is a cross-sectional view schematically showing a partial cross section of the shaft-shaped body and two high-frequency coils when viewed in a plan view along the axis of the shaft-shaped body, and is a view showing a state in which the high-frequency coil moves in accordance with the outer diameter of the large-diameter portion.

[0026] Figure 4 It schematically shows a partial cross section of the shaft-shaped body and a cross-sectional view of three high-frequency coils when viewed in a plan view along the axis of the shaft-shaped body, and is a view showing a state in which the high-frequency coil moves in accordance with the outer diameter of the small-diameter portion.

[0027] Figure 5 It schematically shows a partial cross section of the shaft-shaped body and a cross-sectional view of three high-frequency coils when viewed in a plan view along the axis of the shaft-shaped body, and is a view showing a state in which the high-frequency coil moves in accordance with the outer diameter of the large-diameter portion.

[0028] Figure 6This is a schematic perspective view for explaining the positional relationship between the heating unit and the cooling unit with respect to the shaft-shaped body in the embodiment of the present invention.

[0029] Figure 7 It is a schematic cross-sectional view for explaining the heating temperature range of the shaft-shaped body.

[0030] Figure 8 It is a schematic stereoscopic diagram for explaining the heat density area of ​​the shaft-shaped body.

[0031] Fig. 9 It is a schematic cross-sectional view used to illustrate the magnetic field intensity area and heating temperature area of ​​the shaft.

[0032] Fig.10 It is a schematic cross-sectional view used to illustrate the magnetic field intensity area and heating temperature area of ​​the shaft.

[0033] Fig.11 It is a diagram for explaining a heating area and a heating zone generated on the surface of a shaft-shaped body in an embodiment of the present invention, and is a perspective view schematically showing the shaft-shaped body.

[0034] Fig.12 It is a diagram for explaining a heating area and a heating zone generated on the surface of a shaft-shaped body in an embodiment of the present invention, and is a development diagram in which the surface of the shaft-shaped body is developed.

[0035] Fig.13 This is a diagram for explaining a state where two heating zones overlap each other in an embodiment of the present invention, and is a development diagram in which the surface of a shaft-shaped body is developed.

[0036] Fig.14 This is a diagram for explaining a state in which two heating zones are adjacent to each other in the embodiment of the present invention, and is a development diagram in which the surface of the shaft-shaped body is developed.

[0037] Fig.15 This is a block diagram for explaining a mobile quenching device according to an embodiment of the present invention.

[0038] Fig.16 It is a diagram showing the analysis result of the numerical simulation of Experimental Example 1, and is a diagram showing the heating state of the surface of the shaft-shaped body.

[0039] Fig.17 It is a diagram of the analysis result of the numerical simulation of Experimental Example 2, and is a diagram showing the heating state of the surface of the shaft-shaped body. DETAILED DESCRIPTION

[0040] Below, refer to Figure 1 to Figure 15 The mobile quenching method and mobile quenching device according to the embodiment of the present invention are described. In addition, it is obvious that the present invention is not limited to the following embodiment. In addition, it is obvious that the elements of the following embodiment can be combined within the scope of the present invention.

[0041] like Figure 1 As shown, the traverse hardening device 100 of the present embodiment is a device for traverse hardening an axial body 10 using a high-frequency current. Traverse hardening is a method of traverse hardening while moving a heating unit having a high-frequency induction heating coil (also called a high-frequency coil) and a cooling unit having a cooling ring following the heating unit relative to the heated body. The heated body is, for example, a axial body.

[0042] (Axle body)

[0043] The axial body 10 of the present embodiment includes a large diameter portion 11 (large diameter portion 11A and large diameter portion 11B) and a small diameter portion 12 provided between the large diameter portion 11A and the large diameter portion 11B in the direction along the axis C. The large diameter portion 11A, the large diameter portion 11B, and the small diameter portion 12 are each formed in a cylindrical shape. The central axis of each of the large diameter portion 11A, the large diameter portion 11B, and the small diameter portion 12 is configured to coincide with the common axis, i.e., the axis C. In the present embodiment, the axis C is set as the central axis of the axial body 10. Hereinafter, the portion arranged on one side D1 in the direction along the axis C relative to the small diameter portion 12 is also referred to as the first large diameter portion 11A. The portion arranged on the other side D2 in the direction along the axis C relative to the small diameter portion 12 is also referred to as the second large diameter portion 11B.

[0044] The first large diameter portion 11A, the small diameter portion 12, and the second large diameter portion 11B are each formed in a cylindrical shape, and share the axis C as a common central axis. When observing the cross-section of the large diameter portion 11A and the large diameter portion 11B perpendicular to the axis C, the outer diameter of the small diameter portion 12 is smaller than the outer diameter of each of the large diameter portion 11A and the large diameter portion 11B. It should be noted that in the present embodiment, the outer diameter of the large diameter portion 11A is the same as the outer diameter of the large diameter portion 11B, but the outer diameter of the large diameter portion 11A and the outer diameter of the large diameter portion 11B may be different.

[0045] There is a step portion 13 (step portion 13A and step portion 13B) between the large diameter portion 11A or the large diameter portion 11B and the small diameter portion 12 for connecting them. The step portion 13A and the step portion 13B are inclined at a predetermined angle relative to the axis C of the shaft-shaped body 10. The inclination angle is, for example, in the range of 15° to 90°. It should be noted that in the plane containing the axis C of the shaft-shaped body 10, the outer diameter of the step portion 13 is not particularly limited, but can also be as follows Figure 1 As shown in the example, the large diameter portion 11 and the small diameter portion 12 are smoothly connected. In the mobile quenching device 100 of the present embodiment, the shaft body 10 is arranged so that the axis C is parallel to the vertical direction of the mobile quenching device 100 .

[0046] The shaft-shaped body 10 is formed of a conductive material such as carbon steel in a ferrite phase or a pearlite phase, or low alloy steel containing 95 wt % or more of iron (Fe). The shaft-shaped body may be an axle for a railway vehicle or the like.

[0047] It should be noted that the number of the large diameter portion 11 or the step portion 13 etc. provided in the shaft-shaped body 10 is not limited to Figure 1 For example. The number of the small diameter portion 12, the large diameter portion 11, and the step portion 13 may be 1, 2, or 3, respectively, or may be 4 or more. For example, the axial body that is the object of the mobile quenching method and the mobile quenching device of this embodiment may also be an axial body having a large diameter portion and a small diameter portion. Alternatively, the axial body that is the object of the mobile quenching method and the mobile quenching device of this embodiment may also have either a large diameter portion or a small diameter portion.

[0048] (Mobile quenching device)

[0049] The mobile quenching device 100 includes a heating unit 110 , a cooling unit 120 , a support unit 130 , a heating unit moving device 140 , a cooling unit moving device 150 , and a control unit 160 .

[0050] like Figure 1 As shown, the heating part 110 includes a plurality of high-frequency coils 111 (high-frequency coil 111A and high-frequency coil 111B). The heating part 110 is connected to a heating part moving device 140 as a moving device. The cooling part 120 includes a cooling ring 121. The cooling part 120 is connected to a cooling part moving device 150 as a moving unit. The supporting part 130 includes an upper center piece 131 and a lower center piece 132. The upper center piece 131 supports the first large diameter portion 11A of the shaft-shaped body 10 from above the first large diameter portion 11A. The lower center piece 132 supports the second large diameter portion 11B of the shaft-shaped body 10 from below the second large diameter portion 11B. The upper center piece 131 and the lower center piece 132 support the shaft-shaped body 10 in such a manner that one side D1 in the direction of the axis C is above and the other side D2 is below. In addition, the shaft-shaped body 10 can rotate in the circumferential direction of the shaft-shaped body 10 centered on the axis C while being supported by the upper center piece 131 and the lower center piece 132. The shaft-shaped body 10 can be rotated around the axis of the shaft-shaped body 10 during mobile quenching via the upper center piece 131 and the lower center piece 132 through a driving device (not shown). Rotating the shaft-shaped body 10 around the axis means rotating the shaft-shaped body 10 in any direction in the circumferential direction centered on the axis C of the shaft-shaped body 10. The line connecting the center of the upper center piece 131 and the center of the lower center piece 132 becomes the up-down direction (also referred to as the up-down direction) of the mobile quenching device 100.

[0051] The heating unit moving device 140 supports the heating unit 110 and includes a supporting member 141 and a motor (not shown). The heating unit moving device 140 is mounted on the rack member 180. The rack member 180 extends in the up-down direction. In addition, a pinion 141a is provided on the supporting member 141, and the pinion 141a meshes with the gear portion 180a of the rack member 180. When the motor is driven, the pinion 141a rotates, and the heating unit moving device 140 moves upward or downward relative to the rack member 180.

[0052] The cooling unit moving device 150 supports the cooling unit 120 and includes a supporting member 151 and a motor (not shown). The cooling unit moving device 150 is mounted on the rack member 180. The supporting member 151 is provided with a pinion 151a, and the pinion 151a meshes with the gear portion 180a of the rack member 180. When the motor is driven, the pinion 151a rotates, and the cooling unit moving device 150 moves upward or downward relative to the rack member 180.

[0053] The moving speeds of the heating unit moving device 140 and the cooling unit moving device 150 are independently controlled by the control unit 160. The heating unit moving device 140 supporting the heating unit 110 and the cooling unit moving device 150 supporting the cooling unit 120 move in the up-down direction, and the moving quenching is performed in the axial direction of the shaft-shaped body 10. That is, the up-down direction of the moving quenching device 100 can be said to be the direction in which the moving quenching is performed.

[0054] It should be noted that in Figure 1 In the figure, as the vertical movement mechanism of the heating unit 110 and the cooling unit 120, an example using a rack and a pinion is shown, but the movement mechanism of the present invention is not limited to this, as long as the heating unit 110 and the cooling unit 120 can be moved relative to the shaft body 10 in the vertical direction. In addition, Figure 1 The example in which the heating unit 110 and the cooling unit 120 are moved relative to the fixed shaft body 10 is shown, but the mobile quenching method and mobile quenching device of the present invention are not limited to this method, and the heating unit 110 and the cooling unit 120 may be fixed to make the shaft body 10 move relatively. Figure 1 The example in which the axial direction of the shaft-like body 10 is oriented toward the vertical direction is envisioned, but the mobile quenching method and mobile quenching device of the present invention are not limited to this. The axial direction of the shaft-like body 10 can also be oriented toward the horizontal direction, and the axial direction of the shaft-like body 10 can also be inclined relative to the vertical direction.

[0055] (Heating unit)

[0056] The heating unit 110 of this embodiment includes a plurality of high-frequency coils. Figure 2 Indicates that in the direction along the axis C from Figure 1A schematic top view of the high-frequency coil 111A and the high-frequency coil 111B included in the heating unit 110 and the shaft-shaped body 10 as viewed from the AA direction (direction parallel to the axial direction). Figure 2 In the figure, the shaft body 10 is shown as being broken in the middle of the small diameter portion 12. Figure 2 As shown, the high-frequency coil 111A and the high-frequency coil 111B of the heating unit 110 have a high-frequency induction unit 112A and a high-frequency induction unit 112B formed in a C-shape in a manner that a portion of the high-frequency induction unit 112A surrounds the shaft-shaped body 10 when viewed from above along the axis C of the shaft-shaped body 10. The high-frequency induction unit 112A is connected to the conductive units 113a and 113b at its end. The high-frequency induction unit 112B is also connected to the conductive units 113c and 113d at its end.

[0057] The high-frequency coil 111A and the high-frequency coil 111B are arranged and separated from each other in the circumferential direction (also referred to as the circumferential direction) centered on the axis C of the shaft-shaped body 10. The circumferential direction is parallel to the direction in which the high-frequency induction portion 112A of the high-frequency coil 111A and the high-frequency induction portion 112B of the high-frequency coil 111B extend. That is, the plane (also referred to as the transverse plane) in which the high-frequency induction portion 112A and the high-frequency induction portion 112B extend is perpendicular to the vertical direction of the mobile quenching device 100. In addition, the transverse plane is perpendicular to the axial direction of the shaft-shaped body 10.

[0058] In the above-mentioned horizontal plane, the shapes of the high-frequency induction part 112A of the high-frequency coil 111A and the high-frequency induction part 112B of the high-frequency coil 111B may also be Figure 2 By making the high frequency induction part 112A and the high frequency induction part 112B into an arc shape, there is an advantage that the high frequency coil 111 and the shaft-shaped body 10 are substantially uniformly close to each other in the circumferential direction.

[0059] When the high-frequency induction portion 112A and the high-frequency induction portion 112B are arc-shaped, the diameter of the inscribed circle on the above-mentioned horizontal plane connected to the inner surfaces (surfaces on the side of the axial body 10) of the high-frequency induction portion 112A and the high-frequency induction portion 112B relative to the axis C is preferably larger than the outer diameter of the small diameter portion 12 of the axial body 10 and smaller than the outer diameter of the large diameter portion 11.

[0060] Alternatively, one or both of the high-frequency induction section 112A and the high-frequency induction section 112B may constitute a part of an elliptical shape in the above-mentioned horizontal plane, or may be a shape composed of a plurality of straight lines. In addition, the high-frequency coil 111A and the high-frequency coil 111B may be a shape in which a part of the high-frequency coil 111A and a part of the high-frequency coil 111B overlap when viewed along the axial direction of the shaft-shaped body 10. For example, Figure 2The conductive parts 113a and 113b are located closer to the high-frequency induction part 112B than the conductive parts 113d and 113c, respectively, and the high-frequency induction part 112A and the high-frequency induction part 112B overlap when viewed along the axial direction of the shaft-shaped body 10. In this case, the high-frequency coil 111A and the high-frequency coil 111B are arranged at different positions in the axial direction.

[0061] The conductive portion 113a, the conductive portion 113b, the conductive portion 113c, and the conductive portion 113d extend from each end of the high-frequency induction portion 112A or the high-frequency induction portion 112B in a direction away from the shaft-shaped body 10. More preferably, the conductive portion 113a, the conductive portion 113b, the conductive portion 113c, and the conductive portion 113d extend in a direction orthogonal to the axis C of the shaft-shaped body 10 at the position closest to the high-frequency coil 111A and the high-frequency coil 111B.

[0062] The high-frequency coil 111A and the high-frequency coil 111B are each movable in a direction away from or approaching the shaft-shaped body 10 . Figure 2 The figure shows a state where the high-frequency coil 111A and the high-frequency coil 111B are closest to the small-diameter portion 12 of the shaft-shaped body 10. It is preferable to heat the small-diameter portion 12 in this state.

[0063] on the other hand, Figure 3 Indicates the direction in which the high-frequency coil 111A and the high-frequency coil 111B are separated from the shaft 10 in accordance with the outer diameter of the large-diameter portion 11B ( Figure 3 The large diameter portion 11B of the shaft body 10 is preferably heated in this state. Figure 3 In the state, the high-frequency coil 111A and the high-frequency coil 111B move in the direction of the axis C of the shaft-shaped body 10, and the high-frequency coil 111A and the high-frequency coil 111B are located at the position of the large-diameter portion 11 in the axial direction.

[0064] The conductive parts 113a and 113b of the high-frequency coil 111A are connected to a power source (not shown), and a high-frequency current is supplied from the power source to the high-frequency induction part 112A, thereby generating an induced current in the shaft 10, and generating Joule heat in the shaft 10 through the resistance of the shaft 10. The same is true for the high-frequency coil 111B. For example, the current flows along Figure 2 The current flows in the direction of the arrow i shown in FIG. 11A and FIG. 11B. In the plurality of high frequency coils 111, the current flows in the same direction in the circumferential direction.

[0065] The high frequency coil 111A and the high frequency coil 111B can also be connected to the heating unit 110 via a coil moving unit (not shown). The coil moving unit has a drive motor and a workbench, and is configured to enable the high frequency coil 111A and the high frequency coil 111B to move in a direction orthogonal to the axis C of the shaft body 10, that is, in a transverse plane. The movement of the high frequency coil 111A and the high frequency coil 111B in the transverse plane is controlled by the control unit 160. The above-mentioned power supply can be fixed to the heating unit 110, or can be moved together with the high frequency coil 111 through the coil moving unit.

[0066] The number of the plurality of high-frequency coils 111 provided in the mobile quenching device 100 is preferably two from the viewpoint that the proximity portion between the high-frequency coil 111 and the shaft-shaped body 10 can be continuous and longest in the circumferential direction. In addition, from the viewpoint that the length of the proximity portion can be extended and the gap between the high-frequency coil 111 and the shaft-shaped body 10 will not be too wide even if the plurality of high-frequency coils 111 are narrowed or widened to follow the change in the diameter of the shaft-shaped body 10, it is preferably Figure 4 and Figure 5 The 3 shown. Figure 4 and Figure 5 In the case of the three high-frequency coils 211 (high-frequency coils 211A, 211B, and 211C) shown in the figure, the same structure as the case of using the two high-frequency coils 111 and the heating unit 110 described above can be adopted. It should be noted that the multiple high-frequency coils 111 are arranged separately from each other in the horizontal plane. It is preferred that the multiple high-frequency coils 111 can each move in a direction orthogonal to the axis C of the shaft-shaped body 10 to be subjected to mobile quenching.

[0067] The cross-section of each part in the extension direction of the high-frequency coil 111 can be Figure 1 The rectangular shape shown in the figure may be an ellipse or a perfect circle. In addition, the interior of the high frequency coil 111 may be hollow so that a refrigerant for cooling flows.

[0068] The high-frequency coil 111 is preferably formed of a material such as copper, because it is non-magnetic and not prone to eddy current loss, and has a low resistance and is not prone to Joule loss. In addition, in order to prevent short circuits between the high-frequency coils 111 or between the high-frequency coils 111 and the shaft 10, the surface of the high-frequency coil 111 can also be covered with a material such as a phenolic resin or silicon with high heat resistance and insulation.

[0069] The high-frequency coil 111 may be connected to the heating unit 110 via supporting members (not shown) at the conductive portion 113 a , the conductive portion 113 b , the conductive portion 113 c , and the conductive portion 113 d , for example.

[0070] It should be noted that the plurality of high-frequency coils 111 preferably move at the same speed as one another in the transverse plane.

[0071] (Cooling section)

[0072] The cooling unit 120 is arranged behind the relative moving direction of the heating unit 110. The relative moving direction refers to the direction in which the heating unit 110 moves relative to the shaft body 10 in the axial direction during the moving quenching. Figure 1 The moving quenching is carried out while moving in the direction of D1, so Figure 1 As shown, the cooling unit 120 is disposed at the lower side of the heating unit 110 . Figure 6 The positional relationship between the heating unit 110 and the cooling unit 120 with respect to the shaft-shaped body 10 in this embodiment is exemplified.

[0073] The cooling unit 120 is formed in a ring shape in this embodiment. The cooling unit 120 has an internal space through which the shaft body 10 can be inserted. A plurality of injection nozzles 122 as injection units are formed in the inner peripheral surface 121a of the cooling unit 120 facing the internal space of the cooling ring 121 and separated from each other in the circumferential direction. The cooling medium can be injected into the internal space from each injection nozzle 122. The shape of the cooling unit 120 is not limited to Figure 6 The ring shape shown may also be circular, elliptical, rectangular, etc. in a horizontal plane perpendicular to the up-down direction.

[0074] A pump (not shown) is connected to the cooling unit 120. The pump supplies the cooling medium Cl to the cooling unit 120. The cooling medium Cl supplied to the cooling ring 121 of the cooling unit 120 is sprayed toward the axial body 10 through a plurality of spray nozzles 122 to cool the axial body 10. The cooling medium Cl is, for example, water, oil, an oil-based aqueous solution, etc. The spray amount of the cooling medium Cl can be adjusted by, for example, controlling the pump by the control unit 160.

[0075] In the mobile quenching device 100 of the present embodiment, the shaft-shaped body 10 inserted into the inner side of the plurality of high-frequency coils 111 is rotated relative to the plurality of high-frequency coils 111 about the axis of the shaft-shaped body 10, and the plurality of high-frequency coils 111 are relatively moved relative to the shaft-shaped body 10 in the axial direction of the shaft-shaped body 10, and the mobile quenching is performed while moving the plurality of heating areas (heating area A, heating area B) generated on the surface 10a of the shaft-shaped body 10 by the plurality of high-frequency coils 111. In addition, in the mobile quenching device 100 of the present embodiment, the control unit 160 controls the plurality of heating zones (heating zone a, heating zone b) through which the plurality of heating zones pass to overlap or be adjacent to each other, so as to change at least one of the relative movement speed vl of the plurality of high-frequency coils 111 relative to the axial direction of the shaft-shaped body 10 and the relative rotation speed of the shaft-shaped body 10 relative to the plurality of high-frequency coils 111.

[0076] The heating area (heating area A, heating area B) refers to an area where an induced current is generated in the shaft body 10 by supplying current to the high-frequency induction part 112A or the high-frequency induction part 112B, and Joule heat is generated in the shaft body 10 by the resistance of the shaft body 10. The appropriate heating temperature of the heating area, that is, the temperature at which the hardness after quenching is the highest, varies depending on the material of the shaft body 10. For example, an area that is 50°C higher than the temperature at which austenitization of general steel is completed when heated is used as the heating area. Specifically, an area with a temperature of 850°C or higher on the surface 10a of the shaft body 10 is used as the heating area.

[0077] The length of the heating area (heating area A, heating area B) in the axial direction of the shaft-shaped body 10 is set to T. T is the maximum axial length of the heating area. In addition, the length of the heating area (heating area A, heating area B) in the circumferential direction of the shaft-shaped body 10 is set to wc. wc is the maximum circumferential length of the shaft-shaped body 10. The range of the heating area (heating area A, heating area B) varies depending on the distance between the shaft-shaped body 10 and the high-frequency coil 111, the value of the high-frequency current supplied to the high-frequency coil 111, the material constituting the shaft-shaped body 10, etc.

[0078] For example, as in the example of the present embodiment, when mobile quenching is performed using two high-frequency coils 111, namely, high-frequency coil 111A and high-frequency coil 111B, two heating areas (heating area A and heating area B) are generated by each high-frequency coil 111. The number of heating areas corresponds to the number of high-frequency coils 111. The plurality of high-frequency coils 111 are arranged in the same position in the axial direction of the shaft-shaped body 10, so the positions of heating area A and heating area B in the axial direction of the shaft-shaped body 10 are the same. The circumferential distance between adjacent heating areas in the circumferential direction of the shaft-shaped body 10 is set to wo. wo is the distance between the opposite ends of adjacent heating areas, and is set to the distance along the surface 10a of the shaft-shaped body 10 in the circumferential direction of the shaft-shaped body 10. From the viewpoint of uniform heating, wo is preferably greater than 0.

[0079] Here, the size of the heating area corresponds to the size of the high-frequency induction part of the high-frequency coil 111 that generates the induced current, so Figure 7 As shown, the length T of the heating area in the axial direction of the shaft body 10 is equivalent to the length T' (the range between the dotted lines) of the high-frequency coil 111 in the axial direction of the shaft body 10. Figure 8As shown, the circumferential distance wo between the heating areas adjacent in the circumferential direction of the shaft-shaped body 10 is equivalent to the circumferential distance wo' (the range between the dotted lines) between the high-frequency induction parts 112 (112A or 112B) of the high-frequency coils 111 (111A or 111B) adjacent in the circumferential direction of the shaft-shaped body 10. In addition, the radius R of a certain position in the axial direction of the shaft-shaped body 10 is equivalent to the radius R' of the circle inscribed in the plurality of high-frequency coils 111 at that position. It should be noted that, as Fig. 9 As shown in FIG. 1 , the angle of the high-frequency induction part 112 at a position far from the shaft 10 becomes larger relative to the surface of the shaft 10, deviating from the range of generating magnetic flux lines, and thus does not contribute to the heating area. Specifically, with respect to the portion far from the closest portion of the high-frequency coil 111 and the shaft 10, the portion where the intersection angle between the extension direction of the high-frequency coil 111 and the circumferential direction of the facing shaft is greater than 15° is not included in the heating area. Even if the portion far from the closest portion of the shaft 10 is Fig.10 Like the central part of the high-frequency coil 111, the portion where the intersection angle between the extension direction of the high-frequency coil 111 and the circumferential direction of the facing shaft-shaped body 10 is less than 15° is also included in the heating area (the range between the dotted lines).

[0080] Fig.11 The example shows a portion of the shaft 10, a heating area A and a heating area B generated on the surface 10a of the shaft 10 by induction heating of two high-frequency coils 111, and a heating band a through which the heating area A passes and a heating band b through which the heating area B passes. Figure 2 As exemplified in the examples of FIG. 1 and FIG. 2 , when the high-frequency coil 111A and the high-frequency coil 111B are arranged symmetrically with respect to the axial body 10 in the transverse plane, the heating region A and the heating region B are also generated symmetrically with respect to the axial body 10 .

[0081] The shaft 10 and the high-frequency coil 111 rotate relative to each other around the axis of the shaft 10, that is, in the circumferential direction, and the shaft 10 and the high-frequency coil 111 move relative to each other in the axial direction of the shaft 10. Therefore, the heating area A and the heating area B move in a manner of describing a spiral track on the surface 10a of the shaft 10, respectively, and a heating area A and a heating area B are generated on the surface 10a of the shaft 10. Fig.11 The spiral heating zone a and the heating zone b are shown in the example. In the present embodiment, the surface 10 a of the shaft-shaped body 10 refers to the side surface of the shaft-shaped body 10 .

[0082] Next, the relationship between the positions of the heating zone a and the heating zone b will be described. Fig.12 FIG. 2 shows an expanded view of the surface 10a of the shaft-shaped body 10. Fig.12 In FIG. 1 , an example is shown in which two heating zones A and B generate two heating zones a and b. Figure 12~Figure 14In the figure, the heating zone a is represented by a dotted line, and the heating zone b is represented by a dashed line. Fig.12 The X-axis is parallel to the circumferential direction of the shaft body 10, the Y-axis is parallel to the axial direction, and the Z-axis is parallel to the direction orthogonal to the axis C of the shaft body 10, that is, the radial direction of the shaft body 10. In addition, the X-axis, the Y-axis, and the Z-axis are orthogonal to each other.

[0083] The heating area A and the heating area B adjacent to each other in the circumferential direction of the shaft body 10 are Fig.12 When moving in the positive direction of the X-axis and the positive direction of the Y-axis, Fig.12 In the mobile quenching device 100 of this embodiment, the two heating zones a and b are controlled to overlap or be adjacent to each other. Fig.12 In the example of FIG. 1 , for the purpose of explanation, a state in which the two heating zones a and b do not overlap is shown. In order for the two heating zones a and b to overlap or be adjacent to each other, the following conditions need to be satisfied.

[0084] If the relative angular velocity of the shaft-shaped body 10 relative to the high-frequency coil 111 when the shaft-shaped body 10 is rotated relative to the high-frequency coil 111 is set to ω, and the radius of a certain position in the axial direction of the shaft-shaped body 10 is set to R, then the circumferential rotation speed (circumferential speed) vθ of the surface 10a of the shaft-shaped body 10 at the axial position is expressed as vθ=ω×R. Here, the time t taken for the heating area A to move a distance wo in the circumferential direction is expressed by wo and vθ as wo=vθ×t (Formula A). The time t can also be said to be the time for the heating area A at a certain moment in the circumference of the shaft-shaped body 10 to move to the position of the heating area B at the same moment. As Fig.12 As shown in FIG. 1 , the movement of the heating region A to the position of the heating region B at the same time means that, in the circumferential direction (the direction parallel to the X-axis), the circumferential end of the heating region A moves to the position of the circumferential end of the opposite heating region B. During this time t, the heating region A moves to the position of the heating region A shown by the dotted line on the surface of the shaft body 10, generating a heating zone a.

[0085] If the moving speed of the high-frequency coil 111 in the axial direction of the shaft 10 is set to vl, the axial moving speed of the heating area A and the heating area B on the surface 10a of the shaft 10 also becomes vl. During the above-mentioned time t, the distance l that the heating area A moves in the axial direction (positive direction of the Y coordinate axis) is expressed as l=v1×t. In order to make the heating belt a and the heating belt b overlap or be adjacent to each other, the distance l relative to the axial length T of the heating area A and the heating area B needs to satisfy the relationship of l≦T. That is, the axial moving speed vl of the heating area A and the heating area B needs to satisfy the relationship of vl×t≦T (Formula B).

[0086] Here, the following formula 1 is derived from formula A and formula B.

[0087] (vl / ωR)×wo≦T …Formula 1

[0088] The distance wo and the length T are determined by the size of the heating area A and the heating area B. In addition, R is equivalent to the radius of the shaft body 10 at the location where the heating area A and the heating area B are located. Therefore, when the relative angular velocity ω of the shaft body 10 relative to the plurality of high-frequency coils 111 is constant, control is performed so that the moving speed vl of the high-frequency coil 111 changes according to the radius R of the shaft body 10 at the location where the heating area A and the heating area B are located, thereby satisfying the above formula 1. By performing such control, when performing mobile quenching, the two heating belts a and the heating belts b overlap or are adjacent to each other.

[0089] For example, when the high-frequency coil 111 moves from the large-diameter portion 11 to the small-diameter portion 12, that is, when the radius R of the shaft-shaped body 10 at the location where the heating area A and the heating area B are located changes, by controlling the moving speed vl of the high-frequency coil 111 relative to the shaft-shaped body 10 in the axial direction according to the change in radius R, quenching can be performed while maintaining the state where the two heating zones a and the heating zones b overlap or are adjacent to each other. By setting such a structure, it is possible to suppress the occurrence of insufficiently heated portions and relatively excessively heated portions in the axial and circumferential directions of the shaft-shaped body 10, and to reduce uneven heating.

[0090] In addition, when the moving speed vl is constant, the angular speed ω is controlled so that the angular speed ω changes according to the radius R of the shaft body 10 where the heating area A and the heating area B are located, thereby satisfying the above-mentioned formula 1. By performing such control, when performing mobile quenching, the two heating zones a and b overlap or are adjacent to each other.

[0091] Alternatively, both the moving speed vl and the angular velocity ω may be controlled to satisfy Formula 1.

[0092] In addition, as described above, in the mobile quenching device 100, when the relative angular velocity of the axial body with respect to the multiple high-frequency coils is set to ω, the moving speed is set to vl, the axial length of the high-frequency coil is set to T', the distance between the high-frequency coils adjacent to the circumferential direction of the axial body is set to wo', and the radius of the circle inscribed in the multiple high-frequency coils is set to R', the control unit can also control the moving speed and / or rotation speed in a manner that satisfies the following Formula 2.

[0093] (vl / ωR')×wo'≦T' ...Formula 2

[0094] Fig.13The state where two heating zones a and two heating zones b overlap each other is shown in the example. In this case, even if there is a slight difference in the heating conditions, the entire surface can be reliably quenched.

[0095] Fig.14 Indicates the state where two heating zones a and b are adjacent to each other. Fig.14 In the example, the two heating zones a and b are in contact with each other and share their respective boundaries. In this case, the moving speed of the high-frequency coil 111 can be maximized within the restricted range, so that the quenching can be completed in the shortest time. Fig.13 or Fig.14 For example, as long as it is within the range of Formula 1 of the present invention, the quenching depth can be set to a desired value, and the combination of the moving speed vl and the angular velocity ω can be freely specified based on other indicators.

[0096] The cooling unit 120 may also be controlled to increase the flow rate of the cooling medium when the moving speed v1 is fast and to reduce the flow rate of the cooling medium when the moving speed v1 is slow in coordination with the moving speed v1 so as to keep the cooling capacity constant.

[0097] Fig.15 A block diagram of the mobile quenching device 100 of the present embodiment is shown. In the example of the present embodiment, it is described that the control unit 160 controls the axial movement of the heating unit moving device 140 and the cooling unit moving device 150, the movement of the high-frequency coil 111 in the horizontal plane, or the injection amount of the cooling medium C1 of the pump provided in the cooling unit 120. However, the mobile quenching device 100 may also be configured to include a plurality of control units, each of which controls the movement of these components or the injection amount of the cooling medium.

[0098] Next, a method of performing movement quenching of the shaft-shaped body 10 using the movement quenching device 100 of the present embodiment will be described.

[0099] First, if Figure 1 As shown, the heating part 110 and the cooling part 120 are located on the lower end side of the axial body 10. Next, a high-frequency current is passed through the high-frequency coil 111. In addition, the pump is driven to spray the cooling medium Cl from the multiple injection nozzles 122 of the cooling part 120. Next, the axial body 10 is rotated by the support part 130. Then, the motor is driven to move the heating part moving device 140 and the cooling part moving device 150 upward relative to the rack part 180. Thus, the heating part 110 and the cooling part 120 are sequentially sheathed on the axial body 10 and moved upward.

[0100] In the heating unit 110 , a high frequency current is supplied to the high frequency coil 111 to generate an induced current on the surface 10 a of the shaft 10 , and Joule heat is generated by the resistance of the shaft 10 , so that the surface layer of the shaft 10 is heated to the formation region of the austenite phase.

[0101] Next, the cooling unit 120 rises to the portion heated by the heating unit 110, and sprays the cooling medium Cl to the heated portion of the shaft-shaped body 10. As a result, at least the surface layer of the shaft-shaped body 10 is rapidly cooled to generate a martensitic structure. The heating unit 110 and the cooling unit 120 rise from the lower end to the upper end of the shaft-shaped body 10, and the heating unit 110 and the cooling unit 120 are sequentially heated and cooled, and the surface 10a of the shaft-shaped body 10 is high-frequency quenched.

[0102] In the mobile quenching device 100 of the present embodiment, the axial body 10 inserted into the inner sides of the multiple high-frequency coils 111 is rotated relative to the multiple high-frequency coils 111, and the multiple high-frequency coils 111 are relatively moved relative to the axial body 10 in the axial direction of the axial body 10, while the multiple heating areas (heating area A, heating area B) generated on the surface 10a of the axial body 10 by the multiple high-frequency coils 111 are moved, and mobile quenching is performed.

[0103] In the mobile quenching method of this embodiment, at least one of the moving speed of the multiple high-frequency coils 111 and the relative rotation speed of the shaft-shaped body 10 relative to the multiple high-frequency coils 111 is changed so that the multiple heating zones (heating zone a, heating zone b) through which the multiple heating areas pass overlap or are adjacent to each other. By setting such a structure, it is possible to suppress the occurrence of insufficiently heated parts and relatively excessively heated parts in the axial and circumferential directions of the shaft-shaped body 10, and it is possible to reduce uneven heating.

[0104] The present invention includes the use of a mobile quenching device, which is used to quench an axial body having a small diameter portion and a large diameter portion in the axial direction. The mobile quenching device is characterized in that the mobile quenching device has multiple high-frequency coils and a cooling portion in the axial direction, and has a control portion for controlling the movement of the multiple high-frequency coils and the cooling portion. The control portion can rotate the axial body inserted into the inner side of the multiple high-frequency coils relative to the multiple high-frequency coils, and move the high-frequency coils relative to the axial body in the axial direction, while moving the multiple heating areas generated on the surface of the axial body by the multiple high-frequency coils. The mobile quenching is performed, and the control portion can be controlled in a manner such that at least either the relative movement speed of the multiple high-frequency coils relative to the axial body and the relative rotation speed of the axial body relative to the multiple high-frequency coils can be changed, so that the multiple heating belts through which the multiple heating areas pass overlap or are adjacent to each other.

[0105] In the use of the above-mentioned mobile quenching device, when the relative angular velocity of the axial body with respect to the multiple high-frequency coils is set to ω, the moving speed is set to vl, the axial length of the high-frequency coil is set to T', the distance between the high-frequency coils adjacent to the circumferential direction of the axial body is set to wo', and the radius of the circle inscribed in the multiple high-frequency coils is set to R', the control unit can control the moving speed and / or the rotation speed in a manner that satisfies the following Formula 2.

[0106] (vl / ωR')×wo'≦T' ...Formula 2

[0107] In the use of the above mobile quenching device, the temperature of the heating area can be above 850°C.

[0108] Example

[0109] [Experimental Example 1]

[0110] In order to verify the uneven heating during mobile quenching of an axial body using a mobile quenching device equipped with multiple high-frequency coils, an analysis based on numerical simulation was performed. The axial body is a cylinder with a radius of 100mm made of carbon steel. The axial length of the axial body of the high-frequency coil is 20mm. The multiple high-frequency coils are moved 25mm away from the axial body to match the outer diameter of the axial body. The radius of the circle inscribed in the multiple high-frequency coils when the multiple high-frequency coils are closest to each other is 110mm. At this time, the distance between the high-frequency induction parts of adjacent high-frequency coils is 60mm. The number of high-frequency coils is 3.

[0111] The relative movement speed of the plurality of high frequency coils relative to the shaft in the axial direction of the shaft was 10 mm / sec. The rotation speed (angular velocity) of the high frequency coil relative to the shaft was changed as follows at intervals of 10 cm in the axial direction of the shaft.

[0112] 0cm to 10cm interval A: 0.225rad / sec

[0113] 10cm to 20cm interval B: 0.375rad / sec

[0114] 20cm to 30cm interval C: 0.525rad / sec

[0115] D in the interval from 30cm to 40cm: 0.675rad / sec

[0116] In intervals A and B, the moving speed and angular velocity of the high-frequency coil do not satisfy equation 1, and the multiple heating bands passed through the multiple heating areas do not overlap with each other, but in intervals C and D, the moving speed and angular velocity of the high-frequency coil satisfy equation 1, and the multiple heating bands overlap with each other.

[0117] Fig.162 and 3 show the results of the analysis. As can be seen from the figure, heating unevenness occurs in the sections A and B, but heating unevenness does not occur in the sections C and D, and uniform heating can be performed.

[0118] [Experimental Example 2]

[0119] In Experimental Example 2, the radius of the axial body and the shape of the high-frequency coil are changed, and the same numerical simulation as in Experimental Example 1 is performed. The axial body is a cylinder with a radius of 50 mm made of carbon steel. The axial length of the high-frequency coil is 20 mm. The multiple high-frequency coils are moved 28 mm away from the axial body to match the outer diameter of the axial body, and the radius of the circle inscribed in the multiple high-frequency coils when the multiple high-frequency coils are closest to each other is set to 60 mm. At this time, the distance between the high-frequency induction parts of adjacent high-frequency coils is 50 mm. The number of high-frequency coils is 3.

[0120] The relative movement speed of the plurality of high frequency coils relative to the shaft in the axial direction of the shaft was 10 mm / sec. The rotation speed (angular velocity) of the high frequency coil relative to the shaft was changed as follows at intervals of 10 cm in the axial direction of the shaft.

[0121] 0cm to 10cm interval: 0.45rad / sec

[0122] 10cm to 20cm interval: 0.75rad / sec

[0123] 20cm to 30cm interval: 1.05rad / sec

[0124] 30cm to 40cm interval: 1.35rad / sec

[0125] In section A, the moving speed and angular velocity of the high frequency coil do not satisfy equation 1, and the multiple heating zones through which the multiple heating areas pass do not overlap each other. In section B, the moving speed and angular velocity of the high frequency coil satisfy equation 1, and the multiple heating zones are adjacent to each other. In addition, in sections C and D, the moving speed and angular velocity of the high frequency coil satisfy equation 1, and the multiple heating zones overlap each other.

[0126] Fig.17 2 and 3 show the results of the analysis. As can be seen from the figure, heating unevenness occurs in section A, but heating unevenness is suppressed in sections B, C, and D.

[0127] From the results of these experimental examples, it is understood that the movement quenching method and the movement quenching device of the present invention can reduce the heating unevenness in the axial direction and the circumferential direction of the shaft-shaped body.

[0128] Industrial Applicability

[0129] According to the mobile quenching method and the mobile quenching device of the present invention, the heating unevenness in the axial direction and the circumferential direction of the shaft-shaped body can be reduced, and therefore the industrial value is extremely high.

[0130] Marking Description

[0131] 100: Mobile quenching device

[0132] 110: Heating unit

[0133] 111A, 111B, 211A, 211B, 211C: High frequency coil

[0134] 112A, 112B, 212A, 212B, 212C: High frequency induction unit

[0135] 113a, 113b, 113c, 113d, 213a, 213b, 213c, 213d, 213e, 213f: conductive part

[0136] 120: Cooling unit

[0137] 130: Supporting part

[0138] 140: Heating unit moving device

[0139] 150: Cooling unit moving device

[0140] 160: Control Department

[0141] 10: Axon

[0142] 11A, 11B: Large diameter part

[0143] 12: Trails

[0144] 13A, 13B: Stepped part

[0145] A, B: Heating area

[0146] a, b: Heating belt

Claims

1. A mobile quenching method, wherein a mobile quenching device having a plurality of high-frequency coils is used to quench an axial body, wherein: The shaft-shaped body inserted into the inner side of the plurality of high-frequency coils is rotated relative to the plurality of high-frequency coils, and the plurality of high-frequency coils are moved relative to the shaft-shaped body in the axial direction, and the moving quenching is performed while moving the plurality of heating areas generated by the plurality of high-frequency coils on the surface of the shaft-shaped body. At least one of the relative movement speed of the high-frequency coils in the axial direction with respect to the shaft and the relative rotation speed of the shaft with respect to the high-frequency coils is changed so that the heating zones through which the heating areas pass overlap or are adjacent to each other.

2. The mobile quenching method according to claim 1, characterized in that: When the relative angular velocity of the shaft-shaped body with respect to the plurality of high-frequency coils is set to ω, the moving speed is set to vl, the length of the heating area in the axial direction is set to T, the distance between the heating areas adjacent to each other in the circumferential direction of the shaft-shaped body is set to wo, and the radius of the shaft-shaped body where the heating area is located is set to R, the following formula 1 is satisfied, (vl / ωR)×wo≦T …Formula 1.

3. The mobile quenching method according to claim 1 or 2, characterized in that: The temperature of the heating zone is 850° C. or higher.

4. A mobile quenching device for quenching an axial body, characterized in that: The mobile quenching device includes a plurality of high-frequency coils and a cooling unit in the axial direction, and includes a control unit capable of controlling the movement of the plurality of high-frequency coils and the cooling unit. The control unit is capable of rotating the shaft-shaped body inserted into the plurality of high-frequency coils relative to the plurality of high-frequency coils, and moving the high-frequency coil relative to the shaft-shaped body in the axial direction, while moving a plurality of heating areas generated on the surface of the shaft-shaped body by the plurality of high-frequency coils to perform mobile quenching. The control unit can control in a manner that changes at least one of the relative movement speed of the multiple high-frequency coils with respect to the axial direction of the shaft-shaped body and the relative rotation speed of the shaft-shaped body with respect to the multiple high-frequency coils, so that the multiple heating zones through which the multiple heating areas pass overlap or are adjacent to each other.

5. The mobile quenching device according to claim 4, characterized in that: When the relative angular velocity of the shaft-shaped body with respect to the plurality of high-frequency coils is set to ω, the moving speed is set to vl, the length of the high-frequency coil in the axial direction is set to T', the distance between the high-frequency induction parts of the high-frequency coils adjacent to each other in the circumferential direction of the shaft-shaped body is set to wo', and the radius of the circle inscribed in the plurality of high-frequency coils is set to R', the control unit can control the moving speed and / or the rotation speed in a manner satisfying the following formula 2, (vl / ωR')×wo'≦T' …Formula 2.

6. The mobile quenching device according to claim 4 or 5, characterized in that: The temperature of the heating zone is 850° C. or higher.

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