Mobile quenching device and mobile quenching method

Abstract

A mobile quenching device for performing mobile quenching on a shaft-shaped body in which a large-diameter section having a relatively large outer diameter and a small-diameter section having a relatively small outer diameter are connected via a stepped section, the mobile quenching device being provided with: a plurality of first split coils arranged in a ring shape around a movement center line at a first position on the movement center line; a plurality of second split coils arranged in a ring shape around the movement center line at a second position different from the first position on the movement center line; a first split coil drive unit that causes the first split coils to approach and separate from each other with respect to the movement center line; a second split coil drive unit that moves each of the second split coils closer to and away from the movement center line; and a control unit that controls the first split coil drive unit and the second split coil drive unit.

Description

Technical Field

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

[0002] Conventionally, the fatigue strength of the shaft-shaped body is improved by traverse hardening of the shaft-shaped body by induction heating. The traverse hardening here refers to quenching while moving the coil component or the like in the axial direction relative to the shaft-shaped body.

[0003] Specifically, the coil is moved along the outer peripheral surface in the longitudinal direction of the shaft-shaped body while a current is passed through the coil, thereby induction heating the shaft-shaped body. Then, a coolant is blown to the outer peripheral surface just after heating, so that the shaft-shaped body is quickly cooled and quenched. Here, in the case where the shaft-shaped body is a stepped shaft having a step portion in which the outer diameter changes from a large diameter to a small diameter, or from a small diameter to a large diameter at a midway position in the longitudinal direction, in order to maintain the heating efficiency, it is necessary to appropriately adjust the air gap between the outer peripheral surface of the shaft-shaped body and the coil.

[0004] One of the device structures capable of such adjustment is a method of forming a coil using a plurality of split coils. Specifically, a plurality of split coils are arranged along the circumferential direction of the shaft-like body, and these split coils are connected in series with a power supply. Then, while the current from the power supply flows to each split coil, these split coils are moved along the length direction of the shaft-like body. Then, before each split coil is about to reach the step portion, each split coil is brought close to or separated from the outer peripheral surface of the shaft-like body according to the change in the outer diameter of the shaft-like body, so that the air gap is maintained approximately constant.

[0005] The following patent document 1 discloses a conventional high-frequency induction heating device using such a split coil. The device is equipped with a high-frequency induction heating coil as a split coil. The high-frequency induction heating coil adopts "a high-frequency induction heating coil for heating an axial part, which is used for performing high-frequency induction heating on an axial part having a flange part and an axial part erected at the center of the flange part, an arc part formed between the flange part and the axial part, and an outer peripheral surface of the axial part, wherein a pair of high-frequency induction heating coil components are provided, which are respectively arranged at positions opposite to each other across the axis of the axial part, and are arranged opposite to the arc part and the axial part at a position separated from the arc part and the axial part of the axial part, and the pair of high-frequency induction heating coil components are respectively formed with a curved coil part that is curved in a manner protruding in a direction away from the axis of the axial part."

[0006] According to this device, it is described that "by using a pair of high-frequency induction heating coil components, the pair of high-frequency induction heating coil components can be arranged correspondingly to all various shaft-shaped members having different outer peripheral surface diameters."

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2008-150640 Summary of the invention

[0010] Technical problem to be solved by the invention

[0011] However, in the conventional mobile quenching device including the above-mentioned device, the number of turns of the split coil is one turn, and the number of turns cannot be increased to multiple turns for structural reasons. This is because, when the number of turns of the split coil is increased by overlapping multiple split coils along the length direction of the shaft-like body, the step portion of the shaft-like body where the outer diameter changes cannot be properly mobile quenched. For example, in the mobile quenching of the step portion from the large diameter portion to the small diameter portion, the split coil cannot be brought close to the small diameter portion before the entirety of the split coils overlapping in the length direction of the shaft-like body passes through the large diameter portion. Therefore, the portion of the split coil that ends the heating of the large diameter portion and reaches the front side of the traveling direction of the small diameter portion is inductively heated in a state with a wide air gap between it and the outer peripheral surface of the small diameter portion, which is not preferred from the viewpoint of heating efficiency and poor quenching.

[0012] On the other hand, in the moving quenching of the step portion from the small diameter portion to the large diameter portion, the portion of the split coils overlapping in the longitudinal direction of the shaft-shaped body located on the rear side in the traveling direction cannot pass over the step portion unless the portion located on the front side in the traveling direction quickly moves away from the outer peripheral surface of the small diameter portion before the portion located on the front side in the traveling direction reaches the large diameter portion, even if the small diameter portion is still being heated. Therefore, this is still an undesirable result from the viewpoint of heating efficiency and poor quenching.

[0013] For the reasons described above, the split coils in the past cannot have multiple turns, but usually have one turn. In the case of one turn, the current flowing through the split coil needs to be much higher than that in the case of multiple turns, which easily causes problems such as overheating and short circuit of the split coil.

[0014] The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a mobile quenching device and a mobile quenching method capable of performing mobile quenching on a stepped shaft while suppressing overheating and short circuit of split coils accompanied by a large current.

[0015] Technical solutions for solving technical problems

[0016] In order to solve the above-mentioned problems, the present disclosure proposes the following means.

[0017] (1) A mobile quenching device according to one aspect of the present disclosure is a device for performing mobile quenching on a shaft-shaped body, the shaft-shaped body being formed by connecting a large diameter portion having a relatively large outer diameter and a small diameter portion having a relatively small outer diameter via a step portion, the mobile quenching device comprising:

[0018] A plurality of first split coils, arranged in a ring shape around the moving center line at a first position on the moving center line;

[0019] A plurality of second split coils are arranged in a ring shape around the movement center line at a second position on the movement center line different from the first position;

[0020] a first split coil driving unit, which makes each of the first split coils approach and separate relative to the movement center line;

[0021] A second split coil driving unit causes each of the second split coils to approach and separate relative to the movement center line; and

[0022] The control unit controls the first split coil driving unit and the second split coil driving unit.

[0023] According to the moving quenching device described in (1) above, each first segment coil and each second segment coil are moved around the shaft-shaped body in a state of overlapping arrangement in a direction along the moving center line, and a high-frequency current is passed through each first segment coil and each second segment coil. Thus, each first segment coil and each second segment coil are electromagnetically induced by the shaft-shaped body, and the shaft-shaped body is induction heated.

[0024] When the shaft-shaped body is inductively heated while moving, when each second segment coil is inductively heating the small diameter portion and each first segment coil is inductively heating the step portion, the control unit drives the first segment coil driving unit to gradually move the position of each first segment coil toward the radially outer side of the shaft-shaped body. Through this movement, each first segment coil can be moved along the outer peripheral surface without interfering with the step portion while each second segment coil is along the periphery of the small diameter portion.

[0025] Furthermore, when each second segment coil performs induction heating on the step portion and each first segment coil performs induction heating on the large diameter portion, the control unit drives the second segment coil driving unit to gradually move the position of each second segment coil toward the radially outer side of the shaft-shaped body. As a result, each second segment coil can be moved along the outer peripheral surface of the step portion without interfering with the step portion while each first segment coil is along the periphery of the large diameter portion.

[0026] On the other hand, when induction heating is performed from the large diameter portion over the step portion to the small diameter portion, the order is reversed, and each first segment coil is brought close to the outer peripheral surface of the shaft-shaped body by the first segment coil driving unit, and then each second segment coil is brought close to the outer peripheral surface of the shaft-shaped body by the second segment coil driving unit. The approaching actions of the first segment coil and the second segment coil to the shaft-shaped body are performed respectively according to the outer diameter of the portion to be inductively heated by the first segment coil and the second segment coil.

[0027] Therefore, the problem of interference with the shaft body caused by overlapping each first segment coil and each second segment coil in the direction of the moving center line can be eliminated. As a result, the moving quenching based on the segment coils (first segment coil and second segment coil) with multiple turns can be realized, so the current value of the high-frequency current flowing through each segment coil can be greatly reduced compared with the case of one turn.

[0028] In addition, the coils for heating the shaft-shaped body are not limited to the first split coils and the second split coils. Three or more split coils may be overlapped in the direction of the moving center line. In this case, it is preferred to simultaneously use three or more split coil driving units equal to the number of split coils.

[0029] (2) In the mobile quenching device described in (1) above, the following structure may be adopted:

[0030] It also has a high frequency power supply;

[0031] The control unit controls a current value of a high-frequency current flowing from the high-frequency power source to each of the first segment coils and a current value of a high-frequency current flowing from the high-frequency power source to each of the second segment coils.

[0032] According to the mobile quenching device described in (2), the control unit controls the current value in each first segment coil and the current value in each second segment coil, respectively, so that the current value suitable for the heating portion of the shaft-shaped body can be adjusted. For example, when the corner formed at the connection portion between the step portion and the large diameter portion is heated by each first segment coil, by increasing the current value in each first segment coil, the corner can be sufficiently heated without reducing the moving speed of each first segment coil.

[0033] In addition, as a method of heating the corner to a higher temperature, it is also considered to slow down the movement speed of each first segment coil when passing through the corner. However, in this case, the movement of the cooling ring that cools the heated shaft body also needs to be slowed down, so the movement speed of the cooling ring cannot be constant in the axial direction, which will cause uneven cooling. On the other hand, in this method, it is sufficient not to reduce the movement speed, so there is an advantage that such an undesirable situation will not occur.

[0034] (3) In the mobile quenching device described in (2) above, the following structure may be adopted:

[0035] further comprising a variable resistor that electrically connects each of the first segmented coils and each of the second segmented coils and through which the high-frequency current from the high-frequency power supply flows;

[0036] The control unit distributes and supplies the high-frequency current from the high-frequency power supply to each of the first segment coils and each of the second segment coils while controlling the variable resistor.

[0037] According to the mobile quenching device described in (3) above, the control unit controls the variable resistor so that the current value of the high-frequency current flowing through each first segment coil and the current value of the high-frequency current flowing through each second segment coil can be adjusted to either a different value or a same value. Thus, the high-frequency current corresponding to the heating part of the shaft body can be set for each first segment coil and each second segment coil.

[0038] (4) A motion quenching method according to one aspect of the present disclosure is a method for performing motion quenching on a shaft-shaped body, the shaft-shaped body being formed by connecting a large diameter portion having a relatively large outer diameter and a small diameter portion having a relatively small outer diameter via a step portion, the motion quenching method comprising:

[0039] The axial body is subjected to the movement quenching using a plurality of first segmented coils arranged in a ring shape around the movement center line at a first position on the movement center line and a plurality of second segmented coils arranged in a ring shape around the movement center line at a second position on the movement center line;

[0040] When the transfer quenching is performed, each of the first segment coils and each of the second segment coils are moved closer to and away from the outer peripheral surface of the shaft-shaped body.

[0041] According to the mobile quenching method described in (4), the same effect as that of the mobile quenching device described in (1) can be obtained. Therefore, the problem of interference with the shaft body caused by overlapping each first segment coil and each second segment coil in the direction of the moving center line can be eliminated. As a result, mobile quenching based on multiple turns of the segment coil (first segment coil and second segment coil) can be achieved, so the current value of the high-frequency current flowing through each segment coil can be greatly reduced compared with the case of one turn.

[0042] (5) In the transfer quenching method described in (4), during the transfer quenching, the current value of the high-frequency current flowing through each of the first segmented coils and the current value of the high-frequency current flowing through each of the second segmented coils may be controlled separately.

[0043] According to the mobile quenching method described in (5), the same effect as that of the mobile quenching device described in (2) can be obtained. Therefore, the mobile quenching can be performed while the moving speed of each first segment coil and each second segment coil is kept constant, so the moving speed of the cooling ring following them can also be kept constant to suppress uneven cooling.

[0044] Effects of the Invention

[0045] According to the above-described motion quenching device and motion quenching method, the stepped shaft can be motion quenched while suppressing overheating and short circuit of the split coils caused by a large current. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a side view schematically showing a portion of a moving quenching device according to an embodiment of the present disclosure.

[0047] Figure 2 is a diagram showing a pair of first split coils provided in the mobile quenching device as viewed from above, and is Figure 1 (a) shows a state where the distance between the first segmented coils is narrowed to inductively heat the small diameter portion, and (b) shows a state where the distance between the first segmented coils is widened to inductively heat the large diameter portion.

[0048] Figure 3 1 is a circuit diagram schematically showing electrical connections between a high-frequency power source and the first segmented coil and the second segmented coil.

[0049] Figure 4 1 is a flowchart showing the transfer quenching method in this embodiment.

[0050] Figure 5 is a diagram showing a state in which a shaft-shaped body is quenched while being moved through a step portion, and is Figure 1 A longitudinal section of part B of FIG. The moving quenching is performed in the order of (a), (b), and (c).

[0051] Figure 6 is a diagram showing the simulation results of the mobile quenching device, and includes Figure 1 1 and 2 are longitudinal cross-sectional views of the B portion of the embodiment. (a) shows a conventional example, and (b) shows an embodiment. DETAILED DESCRIPTION

[0052] Hereinafter, an embodiment of the mobile quenching device and the mobile quenching method of the present disclosure will be described based on the accompanying drawings. In the following description, the direction along the central axis CL of the axial body W is sometimes referred to as the length direction, the radial direction of the axial body W centered on the central axis CL is simply referred to as the radial direction, and the circumferential direction of the axial body W is referred to as the circumferential direction. In addition, in order to indicate the direction in which each first split coil and each second split coil of the mobile quenching device is moved, a moving center line is used as the center line of each first split coil and each second split coil. The moving center line is a straight line that coincides with the central axis CL. In addition, sometimes in Figure 1 Along the moving center line, the upper side of the paper is referred to as the upper side, and the lower side of the paper is referred to as the lower side.

[0053] <Mobile quenching equipment>

[0054] First, use Figures 1 to 3 , the structure of the mobile quenching device of this embodiment is described. Here, Figure 1 This is a side view schematically showing a portion of the mobile quenching device. Figure 2 is a diagram showing a pair of first split coils provided in the mobile quenching device as viewed from above, and is Figure 1 A-A view. Figure 3 1 is a circuit diagram schematically showing electrical connections between a high-frequency power source and the first segmented coil and the second segmented coil.

[0055] Figure 1 The traverse hardening device 1 shown is a device for performing traverse hardening on an axle for a railway vehicle or an axial body W such as a ball screw using a high-frequency current.

[0056] First, the shaft-like body W is described. The shaft-like body W is a stepped shaft having a large diameter portion W1, a step portion W2, a small diameter portion W3, a step portion W4, and a large diameter portion W5 coaxially arranged in sequence from the bottom to the top in the longitudinal direction thereof. The large diameter portions W1 and W5 are cylinders with a circular cross section, and have the largest outer diameter in the entire shaft-like body W. The small diameter portion W3 is a cylinder with a circular cross section, and has a smaller outer diameter than the large diameter portions W1 and W5. The step portion W2 has a truncated cone shape connecting the upper end of the large diameter portion W1 and the lower end of the small diameter portion W3. The outer diameter of the step portion W2 gradually decreases from the same outer diameter as the large diameter portion W1 toward the upper direction, and then becomes equal to the outer diameter of the lower end of the small diameter portion W3. The step portion W4 has an inverted truncated cone shape connecting the upper end of the small diameter portion W1 and the lower end of the large diameter portion W5. The outer diameter of the step portion W4 gradually increases upward from the same outer diameter as the upper end of the small diameter portion W3, and then becomes equal to the outer diameter of the lower end of the large diameter portion W5. The large diameter portion W1, the step portion W2, the small diameter portion W3, the step portion W4, and the large diameter portion W5 share the central axis CL. When the outer diameters of the large diameter portions W1 and W5 are assumed to be 100%, the outer diameter of the small diameter portion W3 is, for example, 80% to 90%.

[0057] The shaft-shaped body W is formed of a conductive material such as carbon steel or low-alloy steel containing 95% by weight or more of iron (Fe) as a ferrite phase.

[0058] like Figure 1 As shown, the mobile quenching device includes a support unit 10 , an induction heating unit 20 , a cooling unit 30 , a moving unit 40 , a control unit 50 , and a power supply 60 .

[0059] like Figure 1 As shown, the support portion 10 includes a lower center 11 and an upper center 12. The lower center 11 coaxially supports the large diameter portion W1 of the shaft-shaped body W from below. The upper center 12 coaxially supports the large diameter portion W5 of the shaft-shaped body W from above. The lower center 11 and the upper center 12 support the shaft-shaped body W in a manner such that its central axis CL is along the up-down direction and one end side (the side with the large diameter portion W1) of the shaft-shaped body W is at the bottom and the other end (the side with the large diameter portion W5) is at the top. Between these lower centers 11 and upper centers 12, the shaft-shaped body W is configured to be rotatable around the central axis CL. The lower center 11 and the upper center 12 that support the shaft-shaped body W in this way rotate the shaft-shaped body W around the central axis CL when receiving a driving force from a shaft-shaped body rotating motor (not shown) provided in the support portion 10.

[0060] like Figure 1 As shown, the induction heating unit 20 includes a plurality of coils and a coil support 28 .

[0061] In the present embodiment, two coils, an upper coil 21 and a lower coil 22, are used as a plurality of coils. These upper coils 21 and lower coils 22 have the same structure as each other. Therefore, the upper coil 21 is first described below, and then the lower coil 22 is set to be the same as the upper coil 21 and uses the same figure mark, thereby omitting repeated descriptions. In addition, the coils that heat the axial body W are not limited to the upper coil 21 and the lower coil 22. Three or more coils can also be overlapped in the direction of the moving center line.

[0062] like Figure 2 As shown in (a) of FIG. 1 , the upper coil 21 includes a pair of split coils 21A arranged in a ring shape around a movement center line (central axis CL). Each split coil 21A includes a coil body portion 21a, a first conductor portion 21b, and a second conductor portion 21c.

[0063] The coil body 21a has an arc shape convex in the radial direction with the center axis CL as the center. The inner circumferential surface of the coil body 21a is a concave arc surface centered on the center axis CL, and is arranged with a certain gap size g relative to the outer circumferential surface of the small diameter portion W3 in the circumferential direction. The coil body 21a performs induction heating on the range of about half of the circumference (180° portion) of the axial body W. In addition, as the shape of the coil body 21a, an L-shaped or V-shaped convex in the direction away from the center axis CL may be adopted instead of the arc shape.

[0064] The first wire portion 21b is electrically and mechanically connected to one end of the coil body portion 21a, and extends straightly toward the outer side in a substantially radial direction. The second wire portion 21c is electrically and mechanically connected to the other end of the coil body portion 21a, and extends straightly toward the outer side in a substantially radial direction. The first wire portion 21b and the second wire portion 21c extend along a common straight line.

[0065] The pair of split coils 21A having the above-mentioned structure forms a heating coil coaxially arranged around the shaft-shaped body W by combining the two coil main bodies 21a. Furthermore, when the small diameter portion W3 is inductively heated, the pair of coil main bodies 21a are arranged around the small diameter portion W3 with the gap g spaced therebetween by narrowing the relative position between the pair of split coils 21A.

[0066] On the other hand, Figure 2 As shown in (b) of FIG. 1 , when the large diameter portions W1 and W5 are induction heated, the relative position between the pair of split coils 21A is enlarged, so that the pair of coil main bodies 21 a are arranged around the large diameter portions W1 and W5 .

[0067] When the step portions W2 and W4 are induction heated, the relative position between the pair of split coils 21A is expanded or narrowed according to the change in the outer diameter of the step portions, so that the pair of coil main bodies 21a are arranged around the step portions W2 and W4.

[0068] When the relative positions of the pair of split coils 21A are adjusted according to the outer diameter of the heated portion of the shaft-shaped body W, the gap g is adjusted to be the smallest within a range that does not interfere with the heated portion.

[0069] The above is the description of the upper coil 21 , but in order to distinguish the split coil 21A from the split coil of the lower coil 22 , the split coil of the lower coil 22 is denoted by reference numeral 22A in the following description.

[0070] like Figure 1 As shown, the upper coil 21 and the lower coil 22 are coaxially arranged in a manner that the upper coil 21 overlaps the lower coil 22. That is, each coil body 21a of the upper coil 21 is coaxially arranged to overlap each coil body 21a of the lower coil 22. In addition, regarding the circumferential arrangement of the lower coil 22 and the upper coil 21, the first wire portion 21b and the second wire portion 21c of the lower coil 22 may be arranged to overlap the first wire portion 21b and the second wire portion 21c of the upper coil 21 when viewed from above.

[0071] Alternatively, the arrangement may be such that, in a plan view, the first wire portions 21b and the second wire portions 21c of the lower coil 22 do not overlap with the first wire portions 21b and the second wire portions 21c of the upper coil 21. In this case, the gaps (non-heating range) formed between the first wire portions 21b of the lower coil 22 and the gaps (non-heating range) formed between the second wire portions 21c may be covered by heating the coil main bodies 21a of the upper coil 21. Conversely, the gaps (non-heating range) formed between the first wire portions 21b of the upper coil 21 and the gaps (non-heating range) formed between the second wire portions 21c may be covered by heating the coil main bodies 21a of the lower coil 22.

[0072] In the upper coil 21 and the lower coil 22, the number of coil divisions is set to two, but it is not limited to two and can be set to more than three. For example, when the number of divisions is set to three, the axial body W is heated by one division coil over an angle range of about 120° in the circumferential direction.

[0073] The upper coil 21 and the lower coil 22 described above are manufactured by bending and brazing a hollow tube having a square cross section, and have electrical conductivity. Figure 1 The current transformer 61 of the power supply 60 shown is electrically and mechanically connected. The current transformer 61 allows a high-frequency current to flow through the upper coil 21 and the lower coil 22.

[0074] In addition, the upper coil 21 and the lower coil 22 can be cooled by allowing a coolant to flow through the tubes thereof.

[0075] return Figure 1 The coil support 28 supports the upper coil 21 and the lower coil 22 coaxially with the shaft W in a state where the upper coil 21 and the lower coil 22 overlap in the extending direction of the moving center line. The coil support 28 includes a first guide portion and a second guide portion (not shown), a first split coil driving portion 28a and a second split coil driving portion 28b, and a support body 28c.

[0076] The first and second guide portions, the first and second segment coil driving portions 28a and 28b are fixed to the support base body 28c. The support base body 28c is connected and supported by a current transformer 61 described later via a stay 28d.

[0077] like Figure 2 As shown in (a) and (b) of FIG. 1 , the first guide portion guides the split coils 21A of the upper coil 21 to be able to approach and separate from each other. As the first guide portion, a linear guide provided along the approaching and separating direction can be exemplified.

[0078] The first split coil driving unit 28a applies a driving force to each split coil 21A so that they are close to each other and separated from each other. As the first split coil driving unit 28a, a combination of a stepping motor and a ball screw can be used. In addition, in the present embodiment, each split coil 21A is provided with a first split coil driving unit 28a, but it is not limited to this structure, and one first split coil driving unit 28a can also be used as a common driving source to make a pair of split coils 21A close to each other and separate from each other.

[0079] Similar to the first guide portion, the second guide portion guides the split coils 22A of the lower coil 22 to be able to approach and separate from each other. As the second guide portion, a linear guide provided along the approaching and separating direction can be exemplified.

[0080] The second split coil driving unit 28b provides a driving force for each split coil 22A to move them closer to each other and away from each other. As the second split coil driving unit 28b, a combination of a stepping motor and a ball screw can be used. In addition, in the present embodiment, each split coil 22A is provided with a second split coil driving unit 28b, but it is not limited to this structure, and one second split coil driving unit 28b can also be used as a common driving source to move a pair of split coils 22A closer to each other and away from each other.

[0081] like Figure 1 As shown, the cooling unit 30 includes a cooling ring 31 , a cooling ring support stay 32 , and a coolant circulation pump 33 .

[0082] The cooling ring 31 is formed in a ring shape. An internal space 31a is formed in the cooling ring 31. A plurality of nozzles 31b are formed on the inner peripheral surface of the cooling ring 31 and are separated from each other in the circumferential direction and communicate with the internal space 31a. The shaft-shaped body W is coaxially inserted into the cooling ring 31. The cooling ring 31 is arranged below each of the split coils 21.

[0083] The cooling ring 31 is connected and supported by a coolant circulation pump 33 via a cooling ring support stay 32. The coolant circulation pump 33 supplies a coolant L such as water into the internal space 31a of the cooling ring 31. The coolant L supplied to the internal space 31a is ejected toward the shaft body W through a plurality of nozzles 31b, thereby cooling the shaft body W.

[0084] Figure 1 The moving part 40 shown has a supporting plate 41 , a pinion 42 , a motor 43 and a rack 44 .

[0085] The support base body 28c, the current transformer 61, the cooling ring 31, and the coolant circulation pump 33 are fixed to the support plate 41. The pinion gear 42 is rotatably fixed to the support plate 41. The motor 43 for driving the pinion gear 42 to rotate is mounted on the support plate 41.

[0086] The support plate 41 is connected to the rack 44 via a guide rail (not shown). The support plate 41 is movable relative to the rack 44 in the vertical direction by the guide rail. The pinion 42 is meshed with the teeth of the rack 44. Therefore, when the control unit 50 drives the motor 43, the pinion 42 rotates, and the support plate 41 moves upward or downward relative to the rack 44.

[0087] like Figure 3As shown, the upper coil 21 and the lower coil 22 are connected in parallel with respect to the power supply 60. That is, one end of the upper coil 21 (one end of each segmented coil 21A) and one end of the lower coil 22 (one end of each segmented coil 22A) are electrically connected via the variable resistor 62. Furthermore, the variable resistor 62 is electrically connected to a slider 63a connected to a wiring 63 extending from one end of the power supply 60.

[0088] The other end of upper coil 21 (the other end of each split coil 21A) and the other end of lower coil 22 (the other end of each split coil 22A) are electrically connected via wiring 64. The other end of power source 60 is electrically connected to wiring 64 via wiring 65.

[0089] According to the above configuration, the current flowing from the power supply flows to the upper coil 21 and the lower coil 22 via the wiring 63 and the variable resistor 62. At this time, the control unit 50 controls the slider 63a, thereby adjusting the current value flowing through the upper coil 21 and the current value flowing through the lower coil 22. Therefore, the current value flowing through the upper coil 21 and the current value flowing through the lower coil 22 can be made the same or different depending on the heating position of the shaft-shaped body W.

[0090] The control unit 50 includes a calculation circuit and a memory (not shown). The memory stores a control program for driving the calculation circuit and the like.

[0091] The control unit 50 is connected to the current transformer 61, the first split coil driving unit 28a, the second split coil driving unit 28b, the slider 63a, the coolant circulation pump 33, the motor 43, and the shaft-shaped body rotating motor to control them.

[0092] For example, when the small diameter portion W3 of the shaft body W is subjected to movement quenching, the control unit 50 controls the first segment coil driving unit 28a and the second segment coil driving unit 28b so that Figure 2 On the other hand, when the large diameter portions W1 and W5 of the shaft body W are subjected to the moving quenching, the first split coil driving unit 28a and the second split coil driving unit 28b are controlled by the control unit 50, so that Figure 2 As shown in (b), the gap between the pair of split coils 22A is maximized.

[0093] In addition, when the step portions W2 and W4 of the axial body W are subjected to mobile quenching, the control unit 50 is used to control the first split coil driving unit 28a and the second split coil driving unit 28b, thereby opening and closing a pair of split coils 21A and a pair of split coils 22A following the change in the diameter of the step portions W2 and W4 in the length direction along the center axis CL.

[0094] <Mobile quenching method>

[0095] Next, the transfer quenching method according to the present embodiment will be described.

[0096] Figure 4 1 is a flowchart showing the transfer quenching method in this embodiment.

[0097] The shaft-shaped body W is supported in advance by the support portion 10 so that the central axis CL is along the up-down direction.

[0098] First, in the arrangement step S1, the control unit 50 drives the motor 43 to arrange the upper coil 21 and the lower coil 22 below the large diameter portion W1. Then, the control unit 50 controls the shaft rotating motor to rotate the shaft W around the central axis CL.

[0099] Next, the control unit 50 drives the current transformer 61 to flow high-frequency current through the upper coil 21 and the lower coil 22. At this time, the control unit 50 controls the slider 63a so that the current value flowing through the upper coil 21 and the current value flowing through the lower coil 22 are the same.

[0100] Furthermore, the control unit 50 drives the coolant circulation pump 33 to eject the coolant L from the plurality of nozzles 31b of the cooling ring 31 toward the shaft-shaped body W. In addition, the coolant is supplied to each of the upper coil 21 and the lower coil 22, and cooling of these coils also starts.

[0101] Furthermore, the control unit 50 controls the first split coil driving unit 28a and the second split coil driving unit 28b to expand the intervals between the split coils 21A of the upper coil 21 and the intervals between the split coils 22A of the lower coil 22 in accordance with the outer diameter of the large diameter portion W1.

[0102] When the arrangement step S1 is completed, the process proceeds to the first quenching step S2 .

[0103] In the next first quenching step S2, the control unit 50 drives the motor 43 so that the upper coil 21 and the lower coil 22 move upward as a whole. Then, the large diameter portion W1 is inductively heated from its lower end toward the upper end by the upper coil 21 and the lower coil 22. That is, by the high-frequency current flowing through the upper coil 21 and the lower coil 22, an eddy current flows through the surface of the large diameter portion W1 of the axial body W, and the large diameter portion W1 is inductively heated by the eddy current. At this time, the current value supplied to the upper coil 21 is the same as the current value supplied to the lower coil 22, so the amount of heat applied to the axial body W by these upper coil 21 and the lower coil 22 is the same.

[0104] Then, when the lower coil 22 passes through the cooling ring 31 next, the cooling liquid L is blown toward the outer peripheral surface of the heated large diameter portion W1. Thus, the heated large diameter portion W1 is rapidly cooled and quenched.

[0105] In the next second quenching step S3, the step portion W2 gradually narrowing in diameter upward is inductively heated. In the first quenching step, the intervals between the split coils 21A and the intervals between the split coils 22A are kept constant in each of the upper coil 21 and the lower coil 22, but in the second quenching step S3, the intervals between the split coils 21A and the intervals between the split coils 22A are gradually narrowed. That is, when the step portion W2 is inductively heated from the lower end toward the upper end, the control unit 50 controls the first split coil driving unit 28a and the second split coil driving unit 28b so as to maintain the air gap with the step portion W2 to a constant value and narrow the intervals between the split coils 21A and the intervals between the split coils 22A.

[0106] At this time, in the step portion W2 of the shaft body W, eddy current flows on the surface of the step portion W2 by the high frequency current flowing through each segment coil 21A, 22A, and induction heating is performed by the eddy current. Moreover, when each segment coil 21A, 22A passes through the cooling ring 31 next, the coolant L is blown to the outer peripheral surface of the heated step portion W2. As a result, the heated step portion W2 is rapidly cooled and quenched.

[0107] In the next third quenching step S4, the small diameter portion W3 having the smallest outer diameter and being constant in the length direction is induction heated. In the second quenching step S3, the intervals between the split coils 21A and the intervals between the split coils 22A are gradually narrowed, but in the third quenching step S4, the intervals between the split coils 21A and the intervals between the split coils 22A are kept constant in such a manner that they are minimized.

[0108] That is, when the small diameter portion W3 is inductively heated from its lower end toward its upper end, the control unit 50 controls the first segment coil driving unit 28a and the second segment coil driving unit 28b to maintain the air gap with the small diameter portion W3 constant, and to maintain the intervals between the segment coils 21A and the intervals between the segment coils 22A constant. At this time, the arrangement state of each segment coil 21A is Figure 2 (a).

[0109] On the other hand, in the small diameter portion W3 of the shaft-shaped body W, eddy current flows on the surface thereof by the high frequency current flowing through each segment coil 21A and each segment coil 22A, and induction heating is performed by the eddy current. Then, when each segment coil 21A and each segment coil 22A passes through the cooling ring 31, the cooling liquid L is blown to the outer peripheral surface of the heated small diameter portion W3. Thus, the heated small diameter portion W3 is rapidly cooled and quenched.

[0110] In the following fourth quenching step S5, the step W4 gradually increasing in diameter upward is induction heated. In the third quenching step S4, the intervals between the split coils 21A and the intervals between the split coils 22A are kept constant, but in the fourth quenching step S5, the intervals between the split coils 21A and the intervals between the split coils 22A are gradually increased.

[0111] That is, when the step portion W4 is inductively heated from the lower end toward the upper end between the two split coils 21A, the control unit 50 controls the first split coil driving unit 28a and the second split coil driving unit 28b, thereby maintaining the air gap with the step portion W4 to a certain extent and expanding the interval between each split coil 21A and the interval between each split coil 22A.

[0112] On the other hand, in the step portion W4 of the shaft-shaped body W, eddy current flows on the surface by the high-frequency current flowing through each segment coil 21A and each segment coil 22A, and induction heating is performed by the eddy current. Moreover, when each segment coil 21A and each segment coil 22A passes through the cooling ring 31, the coolant L is blown to the outer peripheral surface of the heated step portion W4. As a result, the heated step portion W4 is rapidly cooled and quenched.

[0113] In the next fifth quenching step S6, the large diameter portion W5 having the largest outer diameter and being constant in the length direction is induction heated. In the fourth quenching step S5, the intervals between the segmented coils 21A and the intervals between the segmented coils 22A are gradually increased, but in the fifth quenching step S6, the intervals between the segmented coils 21A and the intervals between the segmented coils 22A are continuously maintained constant in a manner that the intervals between the segmented coils 21A and the intervals between the segmented coils 22A are the largest.

[0114] That is, when the large diameter portion W5 is inductively heated from its lower end toward its upper end, the control unit 50 controls the first segmentation coil driving unit 28a and the second segmentation coil driving unit 28b to maintain the air gap with the large diameter portion W5 constant and the intervals between the segmentation coils 21A and the intervals between the segmentation coils 22A constant. At this time, the arrangement state of the segmentation coils 21A and the segmentation coils 22A is Figure 2 (b).

[0115] On the other hand, in the large diameter portion W5 of the shaft-shaped body W, eddy current flows on the surface by the high frequency current flowing through each segment coil 21A and each segment coil 22A, and induction heating is performed by the eddy current. Moreover, when each segment coil 21 passes through the cooling ring 31 next, the coolant L is blown to the outer peripheral surface of the heated large diameter portion W5. As a result, the heated large diameter portion W5 is rapidly cooled and quenched.

[0116] Through the above-described steps S1 to S6, the shaft-shaped body W is quenched over its entire length, and all steps are completed. The shaft-shaped body W subjected to the movement quenching over its entire length has a higher hardness than before the movement quenching.

[0117] Here, in the mobile quenching method of the present disclosure, the control unit 50 controls the first split coil driving unit 28a and the second split coil driving unit 28b respectively in each of the process of the upper coil 21 and the lower coil 22 from the large diameter portion W1 to the small diameter portion W3 via the step portion W2 and the process of the upper coil 21 and the lower coil 22 from the small diameter portion W3 to the large diameter portion W5 via the step portion W4. As a result, the upper coil 21 and the lower coil 22 are independently moved closer to and separated from the outer peripheral surface of the shaft-shaped body W, so that, for example, Figure 5 As shown, the upper coil 21 and the lower coil 22 can be arranged along the outer peripheral surface while changing in accordance with the outer diameter of the shaft-shaped body W.

[0118] Figure 5 The diagram shows the process of reaching the large diameter portion W5 from the small diameter portion W3 via the step portion W4. In (a), the state of heating the small diameter portion W3 by both the upper coil 21 and the lower coil 22 is shown. In (b), the state of heating the small diameter portion W3 by the lower coil 22 is shown. On the other hand, the state of heating the step portion W4 by the upper coil 21 is shown. In (c), the state of heating the large diameter portion W5 by both the upper coil 21 and the lower coil 22 is shown.

[0119] First, if Figure 5 As shown in (a), when the small diameter portion W3 is inductively heated, the control unit 50 controls the first split coil driving unit 28a and the second split coil driving unit 28b, so that the upper coil 21 and the lower coil 22 are close to each other with respect to the outer peripheral surface of the small diameter portion W3 to ensure equal air gaps. As a result, the inner peripheral surfaces of the upper coil 21 and the lower coil 22 are arranged at positions where the distances from the moving center line (center axis CL) are equal to each other. Then, in this state, the upper coil 21 and the lower coil 22 are moved upward while performing moving quenching.

[0120] As explained above, in Figure 5In (a), the third quenching step S4 performed by the upper coil 21 and the third quenching step S4 performed by the lower coil 22 are performed simultaneously and in parallel.

[0121] In the next Figure 5 In (b), the fourth quenching step S5 is performed following the third quenching step S4 .

[0122] That is, the upper coil 21 that has completed the induction heating to the upper end of the small diameter portion W3 is gradually moved radially outward by the first split coil driving unit 28a that has received the instruction from the control unit 50, and the step portion W4 is subjected to movement quenching. When performing this movement quenching, the control unit 50 controls so that the air gap formed between the inner peripheral surface of the upper coil 21 and the outer peripheral surface of the step portion W4 is always kept constant. After the movement quenching to the upper end of the step portion W4, the upper coil 21 reaches the lower end of the large diameter portion W5.

[0123] On the other hand, the lower coil 22 at this time is maintained at a position at a certain distance from the moving center line (central axis CL) and continues to perform induction heating of the small diameter portion W3 until it reaches the upper end of the small diameter portion W3. Then, the lower coil 22 that has completed the induction heating to the upper end of the small diameter portion W3 is gradually moved radially outward by the second split coil driving unit 28b that receives the instruction from the control unit 50, and the step portion W4 is subjected to movement quenching. During this movement quenching, the control unit 50 controls so that the air gap formed between the inner peripheral surface of the lower coil 22 and the outer peripheral surface of the step portion W4 is always kept constant.

[0124] As explained above, in Figure 5 In (b), the third quenching step S4 performed by the lower coil 22 and the fourth quenching step S5 performed by the upper coil 21 are performed simultaneously and in parallel.

[0125] In the next Figure 5 In (c), the fifth quenching step S6 is performed.

[0126] That is, the control unit 50 controls the first split coil driving unit 28a and the second split coil driving unit 28b, so that the upper coil 21 and the lower coil 22 are close to each other in a manner of ensuring equal air gaps relative to the outer peripheral surface of the large diameter portion W5. As a result, the inner peripheral surfaces of the upper coil 21 and the lower coil 22 are respectively arranged at positions where the distances from the moving center line (center axis CL) are equal to each other. Moreover, in this state, the upper coil 21 and the lower coil 22 are moved upward while performing moving quenching.

[0127] As explained above, in Figure 5In (c), the fifth quenching step S6 performed by the upper coil 21 and the fifth quenching step S6 performed by the lower coil 22 are performed simultaneously and in parallel.

[0128] The above shows the process of heating from the small diameter portion W3 via the step portion W4 to the large diameter portion W5, but the process of heating from the large diameter portion W1 via the step portion W2 to the small diameter portion W3 is also performed by the control unit 50 while adjusting the radial positions of the upper coil 21 and the lower coil 22 respectively and performing mobile quenching.

[0129] That is, in the second quenching step S3, the upper coil 21 that has completed the induction heating to the upper end of the large diameter portion W1 is gradually moved radially inward by the first split coil driving unit 28a that has received an instruction from the control unit 50, and the step portion W2 is subjected to movement quenching. When performing this movement quenching, the control unit 50 controls so that the air gap formed between the inner peripheral surface of the upper coil 21 and the outer peripheral surface of the step portion W2 is always kept constant. The upper coil 21 that has been movement quenched to the upper end of the step portion W2 reaches the lower end of the small diameter portion W3.

[0130] On the other hand, the lower coil 22 at this time is maintained at a position at a certain distance from the moving center line (central axis CL) and continues to perform induction heating of the large diameter portion W5 until it reaches the upper end of the large diameter portion W5. Then, the lower coil 22 that has completed the induction heating to the upper end of the large diameter portion W5 is gradually moved radially inward by the second split coil driving unit 28b that receives the instruction from the control unit 50, and the step portion W2 is subjected to movement quenching. When performing this movement quenching, the control unit 50 controls so that the air gap formed between the inner peripheral surface of the lower coil 22 and the outer peripheral surface of the step portion W2 is always kept constant.

[0131] As described above, the first quenching step S2 performed by the lower coil 22 and the second quenching step S3 performed by the upper coil 21 are performed simultaneously and in parallel.

[0132] In the configuration steps S1 to the fifth quenching step S6 described above, the upward movement of each segment coil 21A, each segment coil 22A, and the cooling ring 31 relative to the shaft body W is not stopped but continued, and the moving quenching is performed simultaneously. Thus, for example, when moving from the fourth quenching step S5 to the fifth quenching step S6, the moving speed of each segment coil 21A, each segment coil 22A, and the cooling ring 31 is kept constant and the moving quenching is performed. At this time, there is, for example, Figure 5 The corner portion e formed between the step portion W4 and the large diameter portion W5 shown in (a) is a portion to which sufficient heating must be locally applied.

[0133] When heating such a part, it is also considered to slow down the movement speed of the upper coil 21 and the lower coil 22 when they pass through. However, in this case, the movement of the cooling ring 31 that follows the movement is also slowed down, so the movement speed of the cooling ring 31 cannot be constant in the direction of the central axis CL, which will cause uneven cooling.

[0134] In contrast, in the mobile quenching device of this embodiment, Figure 3 As shown, the control unit 50 controls the current value in each segment coil 21A and the current value in each segment coil 22A respectively, so that the current value can be adjusted to be suitable for the heating part of the shaft-shaped body W. For example, when the corner e is heated by each segment coil 21A, the corner can be fully heated without reducing the moving speed of each segment coil 21A by increasing the current value in each segment coil 21A. Therefore, in this mobile quenching device, the moving speed of the upper coil 21 does not need to be reduced, so the above-mentioned cooling unevenness does not occur.

[0135] The following summarizes the above-described embodiments and modifications.

[0136] [1] A mobile quenching device according to one aspect of the present disclosure is a device for performing mobile quenching on a shaft-shaped body (W), wherein the shaft-shaped body (W) is formed by connecting a large diameter portion (W1, W5) having a relatively large outer diameter and a small diameter portion (W3) having a relatively small outer diameter via a step portion (W2, W4), and the mobile quenching device comprises:

[0137] A plurality of first split coils (21A) are arranged in a ring shape around the moving center line at a first position on the moving center line;

[0138] A plurality of second split coils (22A) are arranged in a ring shape around the movement center line at a second position on the movement center line that is different from the first position;

[0139] A first split coil driving unit (28a) causes each of the first split coils (21A) to approach and separate relative to the moving center line;

[0140] A second split coil driving unit (28b) causes each of the second split coils (22A) to move closer to or further away from the movement center line; and

[0141] A control unit (50) controls the first split coil driving unit (28a) and the second split coil driving unit (28b).

[0142] [2] In the mobile quenching device described in [1] above, the following configuration may be adopted:

[0143] It also has a high frequency power supply (60);

[0144] The control unit (50) controls the current value of the high-frequency current flowing from the high-frequency power source (60) to each of the first segmented coils (21A) and the current value of the high-frequency current flowing from the high-frequency power source (60) to each of the second segmented coils (22A).

[0145] [3] In the mobile quenching device described in [2] above, the following structure may be adopted:

[0146] A variable resistor (62) is further provided, which electrically connects each of the first segmented coils (21A) and each of the second segmented coils (22A) and allows the high-frequency current from the high-frequency power supply (60) to flow;

[0147] The control unit (50) controls the variable resistor (62) while distributing and supplying the high-frequency current from the high-frequency power supply (60) to each of the first segmented coils (21A) and each of the second segmented coils (22A).

[0148] [4] A mobile quenching method according to one aspect of the present disclosure is a method for performing mobile quenching on a shaft-shaped body (W), the shaft-shaped body (W) being formed by connecting a large diameter portion (W1, W5) having a relatively large outer diameter and a small diameter portion (W3) having a relatively small outer diameter via a step portion (W2, W4), the mobile quenching method comprising:

[0149] The axial body (W) is subjected to the movement quenching using a plurality of first segmented coils (21A) arranged in a ring shape around the movement center line at a first position on the movement center line and a plurality of second segmented coils (22A) arranged in a ring shape around the movement center line at a second position on the movement center line;

[0150] When the transfer quenching is performed, each of the first segmented coils (21A) and each of the second segmented coils (22A) are moved closer to and away from the outer peripheral surface of the shaft-shaped body (W).

[0151] [5] In the transfer quenching method described in [4] above, when performing the transfer quenching, the current value of the high-frequency current flowing through each of the first segmented coils (21A) and the current value of the high-frequency current flowing through each of the second segmented coils (22A) may be controlled separately.

[0152] Example

[0153] The following describes simulation results of a comparative example of induction heating by a conventional moving quenching device using one-turn split coil and an example of induction heating by a moving quenching device using split coils 21A and 22A according to the first embodiment.

[0154] Figure 6 is a graph showing the simulation results and contains Figure 1 2 is a longitudinal cross-sectional view of the B portion of the shaft. (a) shows a conventional example, and (b) shows an embodiment. In this simulation, the outer diameter of the large diameter portion W5 is set to 200 mm, and the outer diameter of the small diameter portion W3 is set to 170 mm. The material of the shaft-shaped body W is carbon steel.

[0155] The simulation results show that Figure 6 In the comparative example shown in (a), the maximum heating temperature at the corner e was 1287° C. The current flowing through the coil was 28000 A to 45000 A. The time taken to complete the transfer quenching of the predetermined length was 131 seconds.

[0156] On the other hand, Figure 6 In the example shown in (b), the maximum heating temperature at the corner e was 1278° C. The current flowing through each coil was 12600 A to 20250 A. The time taken to complete the transfer quenching of a predetermined length was 132 seconds.

[0157] From the above results, it can be confirmed that in the example using the two-turn coil, the maximum current required for equivalent heating is half that in the comparative example using the one-turn coil, and the current value is significantly reduced.

[0158] Industrial Applicability

[0159] According to the motion quenching device and the motion quenching method disclosed in the present disclosure, it is possible to perform motion quenching on a stepped shaft while suppressing overheating and short circuit of the split coils caused by a large current.

[0160] Description of Reference Numerals

[0161] 21A First split coil

[0162] 22A Second split coil

[0163] 28a First split coil driving unit

[0164] 28b Second split coil driving unit

[0165] 50 Control Department

[0166] 60 High frequency power supply

[0167] 62 Variable resistor

[0168] W Axis

[0169] W1, W5 large diameter part

[0170] W2, W4 step part

[0171] W3 Small diameter section

Claims

1. A mobile quenching device, characterized in that: The invention is a device for performing mobile quenching on a shaft-shaped body, wherein the shaft-shaped body is formed by connecting a large diameter portion with a relatively large outer diameter and a small diameter portion with a relatively small outer diameter via a step portion, and the mobile quenching device comprises: A plurality of first split coils, arranged in a ring shape around the moving center line at a first position on the moving center line; A plurality of second split coils are arranged in a ring shape around the movement center line at a second position on the movement center line different from the first position; a first split coil driving unit, which makes each of the first split coils approach and separate relative to the movement center line; A second split coil driving unit is configured to move each of the second split coils closer to or further away from the moving center line; as well as The control unit controls the first split coil driving unit and the second split coil driving unit.

2. The mobile quenching device according to claim 1, characterized in that: It also has a high frequency power supply; The control unit controls a current value of a high-frequency current flowing from the high-frequency power source to each of the first segment coils and a current value of a high-frequency current flowing from the high-frequency power source to each of the second segment coils.

3. The mobile quenching device according to claim 2, characterized in that: further comprising a variable resistor that electrically connects each of the first segmented coils and each of the second segmented coils and through which the high-frequency current from the high-frequency power supply flows; The control unit distributes and supplies the high-frequency current from the high-frequency power supply to each of the first segment coils and each of the second segment coils while controlling the variable resistor.

4. A mobile quenching method, characterized in that: The present invention relates to a method for performing mobile quenching on a shaft-shaped body, wherein the shaft-shaped body is formed by connecting a large diameter portion with a relatively large outer diameter and a small diameter portion with a relatively small outer diameter via a step portion, and the mobile quenching method comprises: The axial body is subjected to the movement quenching using a plurality of first segmented coils arranged in a ring shape around the movement center line at a first position on the movement center line and a plurality of second segmented coils arranged in a ring shape around the movement center line at a second position on the movement center line; When the transfer quenching is performed, each of the first segment coils and each of the second segment coils are moved closer to and away from the outer peripheral surface of the shaft-shaped body.

5. The mobile quenching method according to claim 4, characterized in that: When the transfer quenching is performed, the current value of the high-frequency current flowing through each of the first segment coils and the current value of the high-frequency current flowing through each of the second segment coils are controlled separately.

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