Mobile quenching method and mobile quenching device

Abstract

Provided is a mobile quenching method in which a shaft-shaped body (10) is heated by a plurality of high-frequency coils (111), a cooling unit (120) is made to follow the high-frequency coils (111) from the rear of the relative movement direction of the high-frequency coils (111) in the axial direction of the shaft-shaped body (10), and the portion heated by the high-frequency coils (111) is cooled by the cooling unit (120). Movement quenching is performed while moving the high-frequency coils (111) in a direction orthogonal to the axial direction of the shaft-shaped body (10) so that the distance from the surface of the shaft-shaped body (10) to each high-frequency coil (111) is constant. The speed of the high-frequency coil (111) in the axial direction when the high-frequency coil (111) passes through the stepped portion (13) is smaller than the speed of the high-frequency coil (111) in the axial direction when the high-frequency coil (111) passes through the small-diameter portion (12) or the large-diameter portion (11).

Description

Technical Field

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

[0002] For steel parts that require a long life, various surface treatments are sometimes performed. 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, in the case of high-frequency quenching of long parts such as steel shafts, so-called traverse hardening is performed. Traverse hardening refers to a method of quenching while moving a high-frequency induction heating coil (also called a high-frequency coil) and a cooling unit relative to the shaft along 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 unit 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 with a desired hardness equal to that of martensite.

[0004] The outer diameter of the shaft-like body is sometimes not constant in the direction along its axis (also referred to as the axial direction). That is, there is a shaft-like 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-like 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-like body is handled by making the split coil advance and retreat in the radial direction of the shaft-like body as the heated body.

[0005] However, although such a variable diameter coil method has the advantage of simplifying the equipment structure, it is important to properly control the moving speed of the coil. The reason is as follows. In order to heat the step portion of the shaft-shaped body uniformly in the axial direction, when the coil is moved along the radial direction of the axial section, it is desired to keep the moving speed along the surface as constant as possible. If the moving speed along the surface is not constant, but the axial moving speed of the coil is constant, the heating is concentrated on the corner of the step, and the heating of the concave part of the step becomes smaller. If you want to suppress this undesirable situation while keeping the axial moving speed of the coil constant, more current is required for heating the concave part of the step. For example, due to the limitation of the upper limit of the current due to the limitation of the cooling capacity of the coil, the undesirable situation that sufficient heating cannot be applied occurs. That is, according to the inventors, the following problem was found: in the previous structure using a split coil as disclosed in Patent Document 1 or Patent Document 2, the step portion and its vicinity connecting the small diameter portion and the large diameter portion as described above cannot be sufficiently heated to obtain the desired tissue.

[0006] Prior art literature

[0007] Patent Literature

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

[0009] Patent Document 2: Japanese Patent Gazette No. 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 thereof is to provide a mobile quenching method and a mobile quenching device capable of performing desired quenching on a step portion and its vicinity in a shaft-shaped body whose outer diameter in the axial direction is not constant.

[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 and a cooling unit to quench a shaft-shaped body having a small diameter portion, a large diameter portion, and a step portion connecting the small diameter portion and the large diameter portion in the axial direction, and is characterized in that the mobile quenching method includes the following steps:

[0014] The shaft-shaped body is heated by the high-frequency coil while the shaft-shaped body inserted into 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.

[0015] The cooling unit is arranged to follow the high-frequency coil from behind the high-frequency coil in the relative movement direction along the axial direction of the shaft-shaped body, and the cooling unit cools the portion heated by the high-frequency coil.

[0016] The high-frequency coils are moved in a direction perpendicular to the axial direction of the shaft-shaped body so that the distance from the surface of the shaft-shaped body to each of the high-frequency coils is constant, while performing movement quenching.

[0017] The axial speed of the high frequency coil when the high frequency coil passes through the step portion is lower than the axial speed of the high frequency coil when the high frequency coil passes through the small diameter portion or the large diameter portion.

[0018] (2) It may also be that according to the mobile quenching method described in (1), when the axial speed of the high-frequency coil when the high-frequency coil passes through the small-diameter portion or the large-diameter portion is set to V0, the axial speed of the high-frequency coil when the high-frequency coil passes through the step portion is set to Vs, and the speed of the plurality of high-frequency coils in a direction orthogonal to the axial direction is set to Vc, the following formula 1 holds true,

[0019] V0 2 ≤Vs 2 +Vc 2 …Formula 1.

[0020] (3) It may also be that according to the mobile quenching method described in (1) or (2), the distance between the high-frequency coil and the cooling part in the axial direction when the high-frequency coil passes through the step portion is smaller than the distance between the high-frequency coil and the cooling part in the axial direction when the high-frequency coil passes through the small diameter portion or the large diameter portion.

[0021] (4) In the mobile quenching method according to any one of (1) to (3), the cooling unit may spray a cooling medium.

[0022] The injection amount or the injection pressure of the cooling medium when the high-frequency coil passes through the step portion is made smaller than the injection amount or the injection pressure of the cooling medium when the high-frequency coil passes through the small-diameter portion or the large-diameter portion.

[0023] (5) A mobile quenching device according to one aspect of the present invention is used to quench a shaft-shaped body having a small diameter portion, a large diameter portion, and a step portion connecting the small diameter portion and the large diameter portion in the axial direction, characterized in that:

[0024] The mobile quenching device,

[0025] A plurality of high-frequency coils and a cooling unit are provided in the axial direction.

[0026] A control unit capable of controlling the movement of the plurality of high-frequency coils and the cooling unit is provided, wherein each of the high-frequency coils has a high-frequency induction unit for heating the shaft-shaped body and a conductive unit connected to the high-frequency induction unit, and is relatively movable relative to the shaft-shaped body in the axial direction and relatively movable in a plane perpendicular to the axial direction, and the cooling unit has an injection unit capable of injecting a cooling medium and is relatively movable relative to the shaft-shaped body in the axial direction,

[0027] The control unit,

[0028] The movement of the high-frequency coil can be controlled in the plane in such a manner that the distance from the surface of the shaft-shaped body to each of the high-frequency coils is constant, and

[0029] The axial speed of the high frequency coil when the high frequency coil passes through the step portion can be controlled to be smaller than the axial speed of the high frequency coil when the high frequency coil passes through the small diameter portion or the large diameter portion.

[0030] (6) It may also be that according to the mobile quenching device described in (6), when the axial speed of the high-frequency coil when the high-frequency coil passes through the small-diameter portion or the large-diameter portion is set to V0, the axial speed of the high-frequency coil when the high-frequency coil passes through the step portion is set to Vs, and the speed of the multiple high-frequency coils in a direction orthogonal to the axial direction is set to Vc, the control unit can control the high-frequency coil in a manner such that the following formula 1 holds true,

[0031] V0 2 ≤Vs 2 +Vc 2 …Formula 1.

[0032] (7) Alternatively, according to the mobile quenching device described in (5) or (6), the control unit can control the distance between the high-frequency coil and the cooling unit in the axial direction when the high-frequency coil passes through the step portion to be smaller than the distance between the high-frequency coil and the cooling unit in the axial direction when the high-frequency coil passes through the small diameter portion or the large diameter portion. (8) Alternatively, according to any one of (5) to (7), the control unit can control the injection amount or injection pressure of the cooling medium when the high-frequency coil passes through the step portion to be smaller than the injection amount or injection pressure of the cooling medium when the high-frequency coil passes through the small diameter portion or the large diameter portion.

[0033] Effects of the Invention

[0034] According to the mobile quenching method and mobile quenching apparatus of the present invention, desired quenching can be performed on the step portion and its vicinity in the shaft-shaped body whose outer diameter in the axial direction is not constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a diagram showing a portion of a mobile quenching device according to an embodiment of the present invention in cross section, and is a side view schematically showing the mobile quenching device.

[0036] 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 from above in the direction 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.

[0037] Figure 3 It schematically shows a partial cross section of the shaft-shaped body and a cross-sectional view of two high-frequency coils when viewed from above in the direction 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 large-diameter portion.

[0038] 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 from above in the direction 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.

[0039] 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 from above in the direction 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 large-diameter portion.

[0040] Figure 6 This 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.

[0041] Figure 7 This is a schematic cross-sectional view of the shaft-shaped body and the high-frequency coil cut along a plane passing through the axis of the shaft-shaped body.

[0042] Figure 8 It schematically shows a partial cross section of the shaft-shaped body and a cross-sectional view of one high-frequency coil when viewed from above in the direction 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.

[0043] Fig. 9 It schematically shows a partial cross section of the shaft-shaped body and a cross-sectional view of one high-frequency coil when viewed from above in the direction 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 large-diameter portion.

[0044] Fig.10 This is a block diagram for explaining the mobile quenching device according to the embodiment of the present invention. DETAILED DESCRIPTION

[0045] Below, refer to Figures 1 to 10 The mobile quenching method and the mobile quenching device as embodiments of the present invention are described. In addition, the present invention is obviously not limited to the following embodiments. In addition, it is obvious that the elements of the following embodiments can be combined within the scope of the present invention.

[0046] like Figure 1 As shown, the traverse hardening device 100 of this 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, an axial body.

[0047] (Axis body)

[0048] The axial body 10 includes a large diameter portion 11 (large diameter portion 11A and large diameter portion 11B) and a small diameter portion 12 arranged 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.

[0049] 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. In addition, in the present embodiment, the outer diameter of the large diameter portion 11A is made 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.

[0050] 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°. In addition, 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 1The axial body 10 is configured such that the large diameter portion 11 and the small diameter portion 12 are smoothly connected as shown in the example. In the mobile quenching device 100 of the present embodiment, the axial body 10 is arranged in such a manner that the axis C is parallel to the vertical direction of the mobile quenching device 100. The axial 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% by weight or more of iron (Fe). The axial body may also be an axle for a railway vehicle, etc.

[0051] In addition, the number of the large diameter portion 11, the step portion 13, etc. provided in the shaft-shaped body 10 is not limited to Figure 1 The number of the small diameter portion 12, the large diameter portion 11, and the step portion 13 may be 1, 2, or 3, or may be 4 or more. For example, the shaft-shaped body that is the object of the mobile quenching method and the mobile quenching device of this embodiment may also be a shaft-shaped body having a large diameter portion and a small diameter portion.

[0052] (Mobile quenching device)

[0053] 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. 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 unit. 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 part 131 and a lower center part 132. The upper center part 131 supports the first large diameter part 11A of the shaft-shaped body 10 from above the first large diameter part 11A. The lower center part 132 supports the second large diameter part 11B of the shaft-shaped body 10 from below the second large diameter part 11B. The upper center part 131 and the lower center part 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 part 131 and the lower center part 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 portion 131 and the lower center portion 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 portion 131 and the center of the lower center portion 132 becomes the up-down direction (also referred to as the up-down direction) of the mobile quenching device 100.

[0054] 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. The configuration is such that 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.

[0055] 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. A pinion 151a is provided on the supporting member 151, 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.

[0056] 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.

[0057] In addition, Figure 1 In the example of using a rack and a pinion as a moving mechanism for the heating unit 110 and the cooling unit 120 in the vertical direction, the moving mechanism of the present invention is not limited thereto, 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. Figure 1 Although the example in which the heating part 110 and the cooling part 120 are moved relative to the fixed shaft body 10 is shown, the mobile quenching method and the mobile quenching device of the present invention are not limited to this method, and the heating part 110 and the cooling part 120 may be fixed so that the shaft body 10 moves relative to the heating part 110 and the cooling part 120. 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.

[0058] (Heating unit)

[0059] The heating unit 110 of this embodiment includes a plurality of high-frequency coils. Figure 2 In the figure, the direction along the axis C is shown 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 is shown in the AA direction (direction parallel to the axial direction). Figure 2 In the figure, the shaft body 10 is shown in a state of being cut away 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 so as to partially surround 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 parts 113a and 113b at its end. The high-frequency induction unit 112B is also connected to the conductive parts 113c and 113d at its end.

[0060] 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 up-down direction of the mobile quenching device 100. In addition, the transverse plane is perpendicular to the axial direction of the shaft-shaped body 10.

[0061] 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 The high-frequency induction part 112A and the high-frequency induction part 112B are in an arc shape, so that the high-frequency coil 111 and the shaft-like body 10 are uniformly and roughly close in the circumferential direction. When the high-frequency induction part 112A and the high-frequency induction part 112B are in an arc shape, the diameter of the inscribed circle on the above-mentioned horizontal plane tangent to each inner surface (surface on the shaft-like body 10 side) of the high-frequency induction part 112A and the high-frequency induction part 112B opposite to each other on the axis C is preferably larger than the outer diameter of the small diameter part 12 of the shaft-like body 10 and smaller than the outer diameter of the large diameter part 11.

[0062] Alternatively, one or both of the high-frequency induction portion 112A and the high-frequency induction portion 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 also be a shape in which a part of the high-frequency coil 111A overlaps a part of the high-frequency coil 111B when viewed from the axial direction of the shaft-shaped body 10. For example, Figure 2The conductive portion 113a and the conductive portion 113b may be located closer to the high frequency induction portion 112B than the conductive portion 113d and the conductive portion 113c. In this case, the high frequency coil 111A and the high frequency coil 111B are arranged at different positions in the axial direction.

[0063] 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 a position where the high-frequency coil 111A and the high-frequency coil 111B are closest.

[0064] 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 11A and 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. Figure 3 The high-frequency coil 111A and the high-frequency coil 111B are shown in the direction away from the shaft body 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.

[0065] 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 high frequency coil 111A and the high frequency coil 111B in the direction of the arrow i shown in FIG. In the plurality of high frequency coils 111 , the current flows in the same direction in the circumferential direction.

[0066] 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 includes 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-shaped 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 it can be moved together with the high-frequency coil 111 through the coil moving unit.

[0067] 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 the 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 gap between the plurality of high-frequency coils 111 is narrowed or widened in accordance with the change in the diameter of the shaft-shaped body 10, it is preferably Figure 4 and Figure 5 The 3 shown. Figure 4 as well as Figure 5 In the case of three high-frequency coils 211 (high-frequency coils 211A, 211B and 211C) as shown, the same configuration as the case of using the two high-frequency coils 111 and the heating unit 110 described above can be adopted. In addition, the plurality of high-frequency coils 111 are arranged to be separated from each other in the horizontal plane. It is preferred that the plurality of high-frequency coils 111 can each be moved in a direction orthogonal to the axis C of the shaft-shaped body 10 to be subjected to mobile quenching.

[0068] 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 elliptical shape or a perfect circular shape. In addition, the interior of the high frequency coil 111 may be hollow so that a refrigerant for cooling flows.

[0069] The high-frequency coil 111 is preferably formed of copper or other materials because it is non-magnetic and does not easily generate eddy current loss, has low resistance and does not easily generate Joule loss. In addition, the surface of the high-frequency coil 111 can also be covered with a material such as a phenolic resin or silicon having high heat resistance and insulation, so that even if the high-frequency coils 111 or the high-frequency coils 111 contact the shaft 10, there will be no short circuit.

[0070] 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.

[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 circumferential 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] Figure 7 A schematic cross-sectional view of the shaft-shaped body 10 and the high-frequency coil 111 is shown along a plane passing through the axis of the shaft-shaped body 10 . Figure 7 The X-axis is perpendicular to the axis C of the shaft body 10, and perpendicular to the Z-axis and the Y-axis. Figure 7 The direction perpendicular to the paper surface is perpendicular to the X coordinate axis and the Z coordinate axis. The Z coordinate axis is parallel to the axis C (the vertical direction of the mobile quenching device 100), and the positive direction of the Z coordinate is consistent with the direction of D1.

[0076] Here, if the cooling ring follows the coil on the basis of controlling the coil to have a constant speed along the surface of the step portion, the moving speed of the cooling ring is greatly reduced when the curved surface portion of the step portion moves. As a result, the undesirable situation that the cooling becomes uneven in the axial direction of the heated body occurs. In the mobile quenching device 100 of the present embodiment, control is performed in a manner that the distance from the surface of the axial body 10 to the high-frequency coil 111A and the high-frequency coil 111B is constant. The distance from the surface of the axial body 10 to the high-frequency coil 111A and the high-frequency coil 111B is defined as the shortest distance between the surface of the axial body 10 and the surface of the high-frequency coil 111. The eddy current generated in the axial body 10 as the heated body by the current flowing in the high-frequency coil 111 varies greatly depending on the distance between the high-frequency coil 111 and the heated body, but by keeping the distance constant to avoid this change, the size of the eddy current becomes constant and the heating is also kept constant. Figure 7 The imaginary line m is a line drawn in a plane passing through the axis of the shaft 10 so that the distance from the surface of the shaft 10 in a direction perpendicular to the surface of the shaft 10 is constant. The position of the high-frequency coil 111 closest to the shaft 10 moves on the imaginary line m.

[0077] Here, the Z coordinate component of the relative moving speed of the high frequency coil 111 with respect to the shaft body 10 is set as Vz, and the X coordinate component of the relative moving speed of the high frequency coil 111 with respect to the shaft body 10 is set as Vx. Vz is equivalent to the relative moving speed of the high frequency coil 111 with respect to the axial direction of the shaft body 10. Vx is equivalent to the relative moving speed of the high frequency coil 111 with respect to the shaft body 10 in the direction orthogonal to the axis C of the shaft body 10.

[0078] Under such a prescribed condition, in the mobile quenching device of the present embodiment, when the high-frequency coil 111 passes through the large-diameter portion 11 or the small-diameter portion 12, the high-frequency coil 111 moves in the axial direction and does not move in the direction orthogonal to the axis C, so Vx is 0. Therefore, the moving speed V0 of the high-frequency coil 111 along the imaginary line m when the high-frequency coil 111 passes through the large-diameter portion 11 or the small-diameter portion 12 is equal to the speed V0z of the Z coordinate component.

[0079] On the other hand, when the high frequency coil 111 passes through the step portion 13, the high frequency coil 111 moves in the axial direction and also moves in a direction orthogonal to the axis C. Therefore, the moving speed V1 of the high frequency coil 111 along the imaginary line m when the high frequency coil 111 passes through the step portion 13 satisfies the relationship of the following formula A.

[0080] V1 2 =V1x 2 +V1z 2 ...Formula A

[0081] Here, V1x is the speed of the X-coordinate component when the high-frequency coil 111 passes through the step portion 13 , and V1z is the speed of the Z-coordinate component when the high-frequency coil 111 passes through the step portion 13 .

[0082] In the mobile quenching device 100 of the present embodiment, it is preferred that the moving speed of the high-frequency coil 111 along the imaginary line m when the high-frequency coil 111 passes through the large-diameter portion 11, the small-diameter portion 12, and the step portion 13 is as constant as possible. In other words, the high-frequency coil 111 moves in a manner that satisfies the relationship V0=V1. Here, based on the relationship V0=V0z, V0≤V1 and the formula A, the following formula B is derived.

[0083] V0z 2 ≤V1x 2 +V1z 2 ...Formula B

[0084] As a control for the mobile quenching device 100, it is preferred to satisfy the relationship V0=V1. However, due to various limitations such as the response performance of actuators such as motors used to move the mobile device and the response performance when the flow rate of the cooling medium Cl sprayed from the cooling section 120 is changed, V0=V1 may not be satisfied sometimes. It is preferred to be as close to V0=V1 as possible within this limitation.

[0085] Due to the eddy current generated in the axial body 10 as the heated body by the current flowing in the high-frequency coil 111, the surface of the heated body is heated, but by keeping the moving distance per unit time constant as described above, the heat energy per unit time in the unit length of the surface of the axial body 10 is also constant.

[0086] According to Formula B, the axial movement speed V1z of the high-frequency coil 111 when the high-frequency coil 111 passes through the step portion 13 is smaller than the axial movement speed V0z of the high-frequency coil 111 when the high-frequency coil 111 passes through the large diameter portion 11 or the small diameter portion 12. In the mobile quenching device 100 of the present embodiment, by setting such a structure, the desired quenching can be performed on the step portion and its vicinity in the axial body whose outer diameter is not constant in the axial direction.

[0087] That is, in the mobile quenching device 100 of the present embodiment, when the axial speed of the high-frequency coil 111 when the high-frequency coil 111 passes through the step portion 13 is set to Vs, and the speed in the direction orthogonal to the axial direction of the high-frequency coil 111 is set to Vc, it is more preferred to control the moving speed of the high-frequency coil 111 in a manner such that the following formula 1 is satisfied.

[0088] V0 2 ≤Vs 2 +Vc 2 …Formula 1

[0089] Vs is the same as the above-mentioned V1z, and Vc is the same as the above-mentioned V1x.

[0090] In addition, if Figure 8 As shown, the distance from the surface of the shaft body 10 to the high-frequency coil 111A and the high-frequency coil 111B is set to be the average distance from the surface of the shaft body 10 in the direction perpendicular to the surface of the shaft body 10 to the high-frequency induction part 112 of the high-frequency coil 111 in the horizontal plane. Figure 8 In the example, the distance d from the surface of the shaft-shaped body 10 of the small diameter portion 12 to the high frequency induction portion 112 of the high frequency coil 111 is constant in the circumferential direction. Fig. 9 In the example, the distance from the surface of the shaft body 10 of the large diameter portion 11 to the high frequency induction portion 112 of the high frequency coil 111 is not constant in the circumferential direction. In this case, the arithmetic mean of the shortest and longest distances from the surface of the shaft body 10 to the high frequency induction portion 112 of the high frequency coil 111 is used. Figure 8 or Fig. 9 In FIG. 1 , only one high-frequency coil 111A is shown for illustration purposes.

[0091] In addition, it is preferred that the plurality of high-frequency coils 111 move at the same speed as each other in the horizontal plane. Generally, if the cooling after heating for quenching is delayed, sometimes a part of the quenched part undergoes pearlite transformation and sufficient quenching cannot be performed. In addition, even in the case of rapid cooling after heating, due to the time from heating to cooling, the grain size of the crystals in the quenched part changes, or the volume fraction of retained austenite changes, thereby changing the hardness and mechanical properties of the material after quenching. However, in the mobile quenching device 100 of the present embodiment, by setting the following structure, it is possible to suppress such changes in the hardness and mechanical properties of the material after quenching.

[0092] In the mobile quenching device 100 of the present embodiment, it is more preferable to control the axial distance between the high-frequency coil 111 and the cooling part 120 when the high-frequency coil 111 passes through the step portion 13 to be smaller than the axial distance between the high-frequency coil 111 and the cooling part 120 when the high-frequency coil 111 passes through the large diameter portion 11 or the small diameter portion 12. By adopting such a structure, the time from heating to the start of cooling is close to constant, and the change in grain size and the change in the volume fraction of retained austenite can be suppressed, so the hardness and mechanical properties of the material become constant. In addition, it has the advantages that the moving speed of the cooling part 120 is close to constant and the cooling capacity is also close to constant. In addition, in this action, specifically, it is preferred to control the axial position of the cooling part 120 so that the end of the cooling part 120 (the end in front of the moving direction) passes through the axial position passed by the end of the high-frequency coil 111 (the end in the rear of the moving direction) after a certain period of time. Through such an action, when the axial movement speed of the high-frequency coil 111 is slow, the axial distance between the high-frequency coil 111 and the cooling unit 120 becomes smaller than when the axial movement speed of the high-frequency coil 111 is fast.

[0093] like Figure 1 As shown as the distance L in FIG, the distance between the high-frequency coil 111 and the cooling unit 120 in the axial direction is the distance from the lower end of the high-frequency coil 111 to the upper end of the cooling unit 120 in the vertical direction of the mobile quenching device 100. In other words, the lower end of the high-frequency coil 111 is the rear end in the moving direction, and the upper end of the cooling unit 120 is the front end in the moving direction. In the mobile quenching device 100 of the present embodiment, it is more preferable to control the injection amount of the cooling medium Cl when the high-frequency coil 111 passes through the step portion 13 to be less than the injection amount of the cooling medium Cl when the high-frequency coil 111 passes through the large diameter portion 11 or the small diameter portion 12.

[0094] As a cooling method, it is preferred to adjust the spraying amount or spraying pressure of the cooling medium Cl to control the cooling capacity so as to suppress the cooling rate on the CCT curve within a range where no hardness change occurs. More specifically, when the axial movement speed of the high-frequency coil 111 is fast, the spraying amount of the cooling medium Cl is increased or the spraying pressure of the cooling medium Cl is enhanced, and when the axial movement speed of the heating coil is slow, the spraying amount of the cooling medium Cl is reduced or the spraying pressure of the cooling medium Cl is weakened. The relationship between the heat transfer coefficient h and the sprayed water volume (water volume density) W, for example, shows that h is proportional to the nth power of W (n is a constant determined by the water cooling conditions) (Mitsutsuka: Cooling Technology of High-Temperature Steel, Iron and Steel / Volume 79, No. 6, p. N405-N416 (1993)). Here, if the movement speed of the cooling unit 120 is fast, the cooling capacity per unit time decreases inversely proportional to the speed, so W is determined in a manner that increases the heat transfer coefficient h by the amount of the speed increase rate.n The amount of sprayed water W. In this way, the cooling capacity is kept constant regardless of the moving speed of the cooling unit 120, so the cooling speed of the heated body can be kept within a desired range.

[0095] Fig.10 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, and the movement on the horizontal plane of the high-frequency coil 111, or the injection amount of the cooling medium Cl of the pump provided in the cooling unit 120. However, the mobile quenching device 100 can also be configured to have a plurality of control units, and each control unit controls these movements and the injection amount of the cooling medium. For example, it can also be provided with a coil position control unit that can independently change the axial movement speed Vz of the axial body 10 of the high-frequency coil 111 and the Vx in the direction orthogonal to the axis C. In addition, it can also be provided with a control unit that can independently control the axial movement speed of the cooling unit 120 under the cooling unit moving device 150 from the movement speed of the heating unit 110 under the heating unit moving device 140.

[0096] Next, a method of performing movement quenching on the shaft-shaped body 10 using the movement quenching device 100 of the present embodiment will be described.

[0097] 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. As a result, the heating part 110 and the cooling part 120 are sequentially inserted into the axial body 10 and moved upward.

[0098] 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 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.

[0099] 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 of the shaft-shaped body 10 is high-frequency quenched.

[0100] In the moving quenching method of the present embodiment, the high-frequency coil 111 is moved in a direction orthogonal to the axial direction of the shaft-shaped body 10 in such a manner that the distance from the surface of the shaft-shaped body 10 to each high-frequency coil 111 is constant, and the axial speed of the high-frequency coil 111 when the high-frequency coil 111 passes through the step portion 13 is lower than the axial speed of the high-frequency coil 111 when the high-frequency coil 111 passes through the small-diameter portion 12 or the large-diameter portion 11. Thus, the desired quenching can be performed on the step portion 13 and its vicinity in the shaft-shaped body 10 whose outer diameter in the axial direction is not constant.

[0101] The present invention includes the use of a mobile quenching device, which is used to quench an axial body having a small diameter portion, a large diameter portion and a step portion connecting the small diameter portion and the 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 capable of controlling the movement of the multiple high-frequency coils and the cooling portion. Each high-frequency coil has a high-frequency induction portion for heating the axial body and a conductive portion connected to the high-frequency induction portion, and can move relative to the axial body and can move relative to the axial direction in a plane perpendicular to the axial direction. The cooling portion has an injection portion capable of injecting a cooling medium, and can move relative to the axial direction in the axial direction. The control portion can control the movement of the high-frequency coil in a plane in a manner that the distance from the surface of the axial body to each high-frequency coil is constant, and can be controlled so that the axial speed of the high-frequency coil when the high-frequency coil passes through the step portion is less than the axial speed of the high-frequency coil when the high-frequency coil passes through the small diameter portion or the large diameter portion.

[0102] In the use of the above-mentioned mobile quenching device, the control unit can control the high-frequency coil in such a way that the following formula 1 holds true, when the axial speed of the high-frequency coil when the high-frequency coil passes through the small-diameter portion or the large-diameter portion is set to V0, the axial speed of the high-frequency coil when the high-frequency coil passes through the step portion is set to Vs, and the speed of multiple high-frequency coils in a direction orthogonal to the axial direction is set to Vc.

[0103] V0 2 ≤Vs 2 +Vc 2 …Formula 1

[0104] In the use of the above-mentioned mobile quenching device, the control unit can also control the axial distance between the high-frequency coil and the cooling unit when the high-frequency coil passes through the step portion to be smaller than the axial distance between the high-frequency coil and the cooling unit when the high-frequency coil passes through the small-diameter portion or the large-diameter portion.

[0105] In the use of the above-mentioned mobile quenching device, the control unit can also control the injection amount or ejection pressure of the cooling medium when the high-frequency coil passes through the step portion to be smaller than the injection amount or ejection pressure of the cooling medium when the high-frequency coil passes through the small diameter portion or the large diameter portion.

[0106] Example

[0107] [Experimental Example 1]

[0108] Using a mobile quenching device with multiple high-frequency coils, an analysis based on numerical simulation was performed to verify the heating state of the step portion when a shaft-shaped body having a small diameter portion, a large diameter portion, and a step portion connecting the small diameter portion and the large diameter portion was mobile quenched. In this experimental example, the shaft-shaped body was made of carbon steel, the outer diameter of the small diameter portion was set to 170 mm, and the outer diameter of the large diameter portion was set to 200 mm. The number of high-frequency coils was 4.

[0109] In this experimental example, when the high-frequency coil is passed through the large diameter portion, the step portion, and the small diameter portion in sequence, the distance between the high-frequency coil and the surface of the axial body is kept constant by controlling the moving speed of the high-frequency coil in the axial direction and in the direction perpendicular to the axial direction of the axial body. In addition, the moving speed of the high-frequency coil is controlled in such a way that the axial speed of the high-frequency coil when the high-frequency coil passes through the step portion is smaller than the axial speed of the high-frequency coil when the high-frequency coil passes through the large diameter portion or the small diameter portion. Specifically, as shown in Table 1 below, the moving speed (feed speed) of the high-frequency coil is constant. Therefore, the axial speed of the high-frequency coil is slower when passing through the step portion than when passing through the large diameter portion or the small diameter portion. The times of 59 seconds to 74 seconds and 105 seconds to 121 seconds are the times for passing through the step portion. In addition, the moving speed of the cooling portion is the same as the axial speed of the high-frequency coil.

[0110] [Table 1]

[0111]

[0112] The temperature of the surface of the shaft-shaped body at the boundary between the large diameter portion and the step portion was 1176° C. The depth from the surface of the region heated to 800° C. or higher in this portion was 5 mm.

[0113] [Experimental Example 2]

[0114] The analysis was performed by the same numerical simulation as in Experimental Example 1. In this experimental example, the same shaft-shaped body and high-frequency coil were used as in Experimental Example 1. The distance between the high-frequency coil and the surface of the shaft-shaped body was made constant by controlling the moving speed of the high-frequency coil in the axial direction of the shaft-shaped body and in the direction perpendicular to the axial direction, which was the same as in Experimental Example 1.

[0115] In this experimental example, the high-frequency coil is controlled to move at a constant speed in the axial direction. Therefore, as shown in Table 2 below, the moving speed (feeding speed) of the high-frequency coil changes in the large diameter part or the small diameter part and the step part. In addition, the moving speed of the cooling part is set to be the same as the axial speed of the high-frequency coil. The time of 36 seconds to 43.4 seconds and 64.1 seconds to 71.95 seconds is the time to pass the step part.

[0116] [Table 2]

[0117]

[0118] The temperature of the surface of the shaft body at the boundary between the large-diameter portion and the stepped portion is 1287 °C. In addition, the depth from the surface of the region heated to 800 °C or higher at this part is 4 mm.

[0119] Based on the above results, in Experimental Example 1, an appropriate heating temperature was obtained on the surface of the stepped portion of the shaft body, and the quenching depth reaching the specified temperature was also sufficient. In addition, as can be seen from Table 1 and Table 2, in Experimental Example 2, in order to achieve the above heating temperature, it was necessary to increase the current amplitude value applied to the high-frequency coil around the stepped portion. On the other hand, in Experimental Example 1, it was found that the desired quenching temperature and quenching depth were obtained while suppressing the increase in the current amplitude value.

[0120] [Experimental Example 3]

[0121] In this experimental example, in order to verify the quenching state when performing moving quenching on a cylindrical shaft body made of carbon steel with a constant outer diameter (170 mm) using a moving quenching device equipped with multiple high-frequency coils, an analysis based on numerical simulation was carried out. The shape of the high-frequency induction part of the high-frequency coil was set to follow the outer diameter of the shaft body, and the number of high-frequency coils was set to 3.

[0122] As shown below, the hardness distribution of the shaft body was calculated when changing the cooling capacity of the cooling part, the distance between the high-frequency coil and the cooling part, and the moving speed of the high-frequency coil and the cooling part, and the surface hardness and sintering depth were evaluated. The evaluation methods for the surface hardness and sintering depth were carried out as follows: the temperature distribution of the shaft body was obtained through magnetic field analysis and heat conduction analysis, and the phase transformation was speculated based on the time-series change of the temperature distribution of each part of the shaft body. On this basis, the hardness after cooling was calculated. Tables 3 and 4 show the ratio of the surface hardness when the hardness of the martensite fraction of 90% is set to 1, and Tables 5 and 6 show the thickness (mm, sintering depth) from the surface of the range where the hardness becomes 70% or more of the martensite fraction. The cooling capacity of the cooling part in the table refers to the convective heat transfer coefficient on the surface of the shaft body. The distance between the high-frequency coil and the cooling part is as specified in the above embodiment. In addition, the high-frequency coil and the cooling part move at the same speed as shown in the table in the axial direction of the shaft body.

[0123] [Table 3]

[0124]

[0125] [Table 4]

[0126]

[0127] [Table 5]

[0128]

[0129] [Table 6]

[0130]

[0131] It can be seen from the results of Tables 3 and 4 that if the moving speed of the high-frequency coil and the cooling part slows down, there is a tendency for the hardness to decrease due to quenching. On the other hand, if the distance between the high-frequency coil and the cooling part is shortened, the reduction in hardness can be suppressed. It can be seen from this that when the shaft-shaped body has a step portion, and the axial speed of the high-frequency coil when the high-frequency coil passes through the step portion is less than the axial speed of the high-frequency coil when the high-frequency coil passes through the small diameter portion or the large diameter portion, the quenching hardness can be ensured by making the distance between the high-frequency coil and the cooling part in the axial direction of the shaft-shaped body when the high-frequency coil passes through the step portion smaller than the distance between the high-frequency coil and the cooling part in the axial direction when the high-frequency coil passes through the small diameter portion or the large diameter portion.

[0132] In addition, it can be seen from the results of Tables 3 and 4 that if the moving speed of the high-frequency coil and the cooling part is slowed down, there is a tendency for the hardness to decrease due to quenching, but the reduction in hardness can be suppressed by increasing the cooling capacity of the cooling part. It can be seen from this that the quenching hardness can be ensured by making the injection amount or ejection pressure of the cooling medium when the high-frequency coil passes through the step part smaller than the injection amount or ejection pressure of the cooling medium when the high-frequency coil passes through the small diameter part or the large diameter part.

[0133] Furthermore, it can be seen from the results of Tables 5 and 6 that the sintering depth can be kept constant by adjusting the cooling capacity of the cooling unit in coordination with the moving speed of the coil and the cooling unit. In Table 5, the convection heat transfer rate is adjusted in coordination with the sintering depth of 5 mm. In Table 6, the convection heat transfer rate is adjusted in coordination with the sintering depth of 3 mm.

[0134] According to the results of this experimental example, in addition to the speed control of the heating coil, the desired quenching hardness can be ensured by properly controlling the moving speed and cooling capacity of the cooling unit. This can suppress the change in grain size and the change in the volume fraction of retained austenite, so that the hardness and mechanical properties of the material can be kept constant.

[0135] Industrial Applicability

[0136] According to the mobile quenching method and mobile quenching device of the present invention, desired quenching can be performed on the step portion and its vicinity in a shaft-shaped body whose outer diameter in the axial direction is not constant, and therefore the industrial value is extremely high.

[0137] Description of Reference Numerals

[0138] 100 Mobile quenching device

[0139] 110 Heating unit

[0140] 111A, 111B, 211A, 211B, 211C high frequency coils

[0141] 112A, 112B, 212A, 212B, 212C high frequency induction part 113a, 113b, 113c, 113d, 213a, 213b, 213c, 213d, 213e, 213f conductive part

[0142] 120 Cooling unit

[0143] 130 Supporting part

[0144] 140 Heating unit moving device

[0145] 150 Cooling unit moving device

[0146] 160 Control Department

[0147] 10 Axon

[0148] 11A, 11B large diameter part

[0149] 12 Trails

[0150] 13A, 13B step part

Claims

1. A moving quenching method, using a moving quenching device having a plurality of high-frequency coils and a cooling unit, to quench an axial body having a small diameter portion, a large diameter portion, and a step portion connecting the small diameter portion and the large diameter portion in the axial direction, characterized in that: The mobile quenching method comprises the following steps: The shaft-shaped body is heated by the high-frequency coil while the shaft-shaped body inserted into 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. The cooling unit is arranged to follow the high-frequency coil from behind the high-frequency coil in the relative movement direction along the axial direction of the shaft-shaped body, and the cooling unit cools the portion heated by the high-frequency coil. The high-frequency coils are moved in a direction perpendicular to the axial direction of the shaft-shaped body so that the distance from the surface of the shaft-shaped body to each of the high-frequency coils is constant, while performing movement quenching. The axial speed of the high frequency coil when the high frequency coil passes through the step portion is lower than the axial speed of the high frequency coil when the high frequency coil passes through the small diameter portion or the large diameter portion.

2. The mobile quenching method according to claim 1, characterized in that: When the axial speed of the high-frequency coil when the high-frequency coil passes through the small-diameter portion or the large-diameter portion is set to V0, the axial speed of the high-frequency coil when the high-frequency coil passes through the step portion is set to Vs, and the speeds of the multiple high-frequency coils in a direction orthogonal to the axial direction are set to Vc, the following formula 1 holds true, V0 2 ≤Vs 2 +Vc 2 …Formula 1.

3. The mobile quenching method according to claim 1 or 2, characterized in that: The distance between the high-frequency coil and the cooling portion in the axial direction when the high-frequency coil passes through the step portion is smaller than the distance between the high-frequency coil and the cooling portion in the axial direction when the high-frequency coil passes through the small-diameter portion or the large-diameter portion.

4. The mobile quenching method according to any one of claims 1 to 3, characterized in that: The cooling unit sprays a cooling medium, The injection amount or the injection pressure of the cooling medium when the high-frequency coil passes through the step portion is made smaller than the injection amount or the injection pressure of the cooling medium when the high-frequency coil passes through the small-diameter portion or the large-diameter portion.

5. A mobile quenching device for quenching an axial body having a small diameter portion, a large diameter portion, and a step portion connecting the small diameter portion and the large diameter portion in the axial direction, characterized in that: The mobile quenching device, A plurality of high-frequency coils and a cooling unit are provided in the axial direction. A control unit capable of controlling the movement of the plurality of high-frequency coils and the cooling unit is provided, wherein each of the high-frequency coils has a high-frequency induction unit for heating the shaft-shaped body and a conductive unit connected to the high-frequency induction unit, and is capable of relative movement relative to the shaft-shaped body in the axial direction and in a plane perpendicular to the axial direction. The cooling unit has a spraying portion capable of spraying a cooling medium, and is relatively movable in the axial direction with respect to the shaft-shaped body. The control unit, The movement of the high-frequency coil can be controlled in the plane in such a manner that the distance from the surface of the shaft-shaped body to each of the high-frequency coils is constant, and The axial speed of the high frequency coil when the high frequency coil passes through the step portion can be controlled to be smaller than the axial speed of the high frequency coil when the high frequency coil passes through the small diameter portion or the large diameter portion.

6. The mobile quenching device according to claim 5, characterized in that: When the axial speed of the high-frequency coil when the high-frequency coil passes through the small-diameter portion or the large-diameter portion is set to V0, the axial speed of the high-frequency coil when the high-frequency coil passes through the step portion is set to Vs, and the speeds of the plurality of high-frequency coils in a direction orthogonal to the axial direction are set to Vc, the control unit can control the high-frequency coil in a manner such that the following formula 1 holds true. V0 2 ≤Vs 2 +Vc 2 …Formula 1.

7. The mobile quenching device according to claim 5 or 6, characterized in that: The control unit can control the distance between the high-frequency coil and the cooling unit in the axial direction when the high-frequency coil passes through the step portion to be smaller than the distance between the high-frequency coil and the cooling unit in the axial direction when the high-frequency coil passes through the small-diameter portion or the large-diameter portion.

8. The mobile quenching device according to any one of claims 5 to 7, characterized in that: The control unit may control the injection amount or the injection pressure of the cooling medium when the high-frequency coil passes through the step portion to be smaller than the injection amount or the injection pressure when the high-frequency coil passes through the small-diameter portion or the large-diameter portion.

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