Induction heating method and manufacturing method for ring member, ring member, bearing, induction heating device, manufacturing method for bearing, manufacturing method for vehicle, and manufacturing method for mechanical equipment

Abstract

A current is supplied to the induction coil to inductively heat the annular member. The induction heating step includes induction heating of the annular member with an induction coil (17) disposed inside the annular member in the radial direction in a state where a substantial coil is not disposed outside the annular member in the radial direction, or induction heating of the annular member with an induction coil (17) disposed inside the annular member in the radial direction in a state where a substantial coil is not disposed inside the annular member in the radial direction. The annular member is inductively heated by an induction coil (18) disposed on the outside in the radial direction of the annular member. The effective length of the induction coils (17, 18) is set to be greater than the axial length of the annular member.

Description

Technical Field

[0001] The present invention relates to a method for induction heating a metal annular member such as an outer ring or an inner ring included in a bearing, for example.

[0002] This application claims priority based on Japanese Patent Application No. 2022-174235 filed on October 31, 2022, and incorporates its content herein by reference. Background Art

[0003] For example, in order to improve the toughness of the core while ensuring the strength and hardness, particularly the hardness of the raceway surface in contact with the rolling elements, quenching treatment and tempering treatment are performed on the outer ring or the inner ring included in the bearing. Both the quenching treatment and the tempering treatment are performed by heating an annular member (workpiece) such as the outer ring or the inner ring to a specified temperature, holding for a specified time, and then cooling.

[0004] Japanese Unexamined Patent Application Publication No. 2019-185882 describes a method for induction heating an annular member by arranging a series of outer diameter side coil portions and inner diameter side coil portions on the radially outer side and the radially inner side of the annular member (short cylindrical workpiece) and energizing the outer diameter side coil portions and the inner diameter side coil portions. In the method described in Japanese Unexamined Patent Application Publication No. 2019-185882, since the outer diameter side coil portions and the inner diameter side coil portions are connected in series, the current values flowing through the outer diameter side coil portions and the inner diameter side coil portions can be made the same, and the outer diameter side region and the inner diameter side region of the annular member can be heated simultaneously under substantially the same conditions.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-185882 Summary of the Invention

[0008] However, in the method described in Japanese Unexamined Patent Application Publication No. 2019-185882, when an annular member having a different radial thickness depending on the axial position, such as an outer ring having an outer ring raceway on the inner surface or an inner ring having an inner ring raceway on the outer surface, is used as an object, the temperature rising rate of the portion with a large radial thickness is slower than that of the portion with a small radial thickness. Therefore, it is difficult to uniformly heat the entire annular member.

[0009] In the induction heating of such a ring-shaped component, it can be considered to set the shape of the bus bar on the inner surface of the outer diameter side coil portion to the shape along the bus bar shape of the outer surface of the ring-shaped component, and set the shape of the bus bar on the outer surface of the inner diameter side coil portion to the shape along the bus bar shape of the inner surface of the ring-shaped component. Making the current value supplied to the coil smaller may suppress the difference in the heating rate based on the axial position of the ring-shaped component to be small, but this will result in a decrease in productivity. In addition, it is necessary to precisely limit the positional relationship between the outer diameter side coil portion and the inner diameter side coil portion and the ring-shaped component. When heating ring-shaped components with different diameters or shapes, it is necessary to prepare coils that match the ring-shaped components. Therefore, when dealing with small batches of ring-shaped components, there will be a problem of increased manufacturing costs.

[0010] An aspect of the present invention aims to provide an induction heating method capable of heating a ring-shaped component as a whole substantially uniformly and efficiently.

[0011] An induction heating method for a ring-shaped component according to an aspect of the present invention includes a step of supplying current to an induction coil to perform induction heating on the ring-shaped component. The induction heating step includes the following processing: performing induction heating on the ring-shaped component by using the induction coil disposed inside the ring-shaped component in a state where no substantial coil is disposed outside the ring-shaped component in the radial direction, or performing induction heating on the ring-shaped component by using the induction coil disposed outside the ring-shaped component in a state where no substantial coil is disposed inside the ring-shaped component in the radial direction. The effective length of the induction coil is set to be larger than the axial length of the ring-shaped component.

[0012] An induction heating method for a ring-shaped component according to another aspect of the present invention includes: a step of preparing a first coil disposed inside the ring-shaped component in the radial direction and a second coil disposed outside the ring-shaped component in the radial direction; a first heating step of supplying current to one of the first coil and the second outer coil to perform induction heating on the ring-shaped component so that at least a part of the ring-shaped component reaches a first target temperature; and a second heating step of, after the first heating step, supplying current to the other of the first coil and the second coil to perform induction heating on the ring-shaped component so that at least a part of the ring-shaped component reaches a second target temperature higher than the first target temperature.

[0013] In the induction heating method for a ring-shaped component according to an aspect of the present invention, the ring-shaped component can be used as the inner ring or outer ring of a rolling bearing such as an angular contact ball bearing, a deep groove ball bearing, a roller bearing, or a tapered roller bearing.

[0014] Alternatively, in the induction heating method for a ring-shaped component according to an aspect of the present invention, the ring-shaped component can be used as the outer ring or inner ring of a multi-row rolling bearing or a sliding bearing.

[0015] In the induction heating method of the ring-shaped component according to one aspect of the present invention, the ring-shaped component can be used as the outer ring, and the outer diameter heating process is performed after the inner diameter heating process is performed.

[0016] Alternatively, in the induction heating method of the ring-shaped component according to one aspect of the present invention, the ring-shaped component can be used as the inner ring, and the inner diameter heating process is performed after the outer diameter heating process is performed.

[0017] In the manufacturing method of the ring-shaped component according to one aspect of the present invention, in order to manufacture the ring-shaped component, the ring-shaped component is heated by using the induction heating method of the ring-shaped component according to one aspect of the present invention, and thus heat treatment such as quenching, tempering, annealing, and / or normalizing is performed on the ring-shaped component.

[0018] In the manufacturing method of the rolling bearing according to one aspect of the present invention, in order to manufacture a rolling bearing including an inner ring having an inner ring race on an outer surface, an outer ring having an outer ring race on an inner surface, and a plurality of rolling elements arranged between the inner ring race and the outer ring race in a freely rolling manner, the inner ring and / or the outer ring is heated by using the induction heating method of the ring-shaped component according to one aspect of the present invention, and thus heat treatment is performed on the inner ring and / or the outer ring.

[0019] In the manufacturing method of the vehicle according to one aspect of the present invention, in order to manufacture a vehicle including a ring-shaped component, the ring-shaped component is heated by using the induction heating method of the ring-shaped component according to one aspect of the present invention, and thus heat treatment is performed on the ring-shaped component.

[0020] In the manufacturing method of the mechanical equipment according to one aspect of the present invention, in order to manufacture mechanical equipment including a ring-shaped component, the ring-shaped component is heated by using the induction heating method of the ring-shaped component according to one aspect of the present invention, and thus heat treatment is performed on the ring-shaped component.

[0021] The induction heating device for a ring-shaped component according to one aspect of the present invention includes: a first coil disposed radially inside the ring-shaped component; a second coil disposed radially outside the ring-shaped component; and a power supply device that supplies current to the first coil and the second coil. The power supply device includes: a first mode in which current is supplied to one of the first coil and the second coil to perform induction heating on the ring-shaped component so that at least a part of the ring-shaped component reaches a first target temperature; and a second mode in which current is supplied to the other of the first coil and the second coil to perform induction heating on the ring-shaped component so that at least a part of the ring-shaped component reaches a second target temperature higher than the first target temperature.

[0022] Advantages of the Invention

[0023] By the induction heating method of the annular member according to one aspect of the present invention, the entire annular member can be heated substantially uniformly and efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a cross-sectional view showing an example of a rolling bearing having an outer ring and an inner ring.

[0025] Figure 2 It is a diagram schematically showing an induction heating device.

[0026] Figure 3 It is a cross-sectional view showing a case where the outer ring is induction heated in the first embodiment.

[0027] Figure 4 It is a diagram schematically showing an example of the arrangement of the annular member relative to the induction coil.

[0028] Figure 5 It is a graph schematically showing the temperature change of the outer ring when the outer ring is induction heated.

[0029] Figure 6 It is a flowchart showing an example of the steps of performing quenching treatment and tempering treatment on the outer ring.

[0030] Figure 7 Showing a modified example, it is a cross-sectional view showing a case where the outer ring is induction heated.

[0031] Figure 8 Showing another modified example, it is a cross-sectional view showing a case where the outer ring is induction heated.

[0032] Figure 9 It is a cross-sectional view showing a case where the outer ring is induction heated in the second embodiment.

[0033] Figure 10 It is a cross-sectional view showing a case where the outer ring is induction heated in the third embodiment.

[0034] Figure 11 It is a cross-sectional view showing a case where the inner ring is induction heated in the fourth embodiment.

[0035] Figure 12 It is a cross-sectional view showing a case where the inner ring is induction heated in the fifth embodiment.

[0036] Figure 13 It is a cross-sectional view showing a case where the inner ring is induction heated in the sixth embodiment.

[0037] Figure 14Cross-sectional view showing the case of induction heating of the ring-shaped component in the seventh embodiment.

[0038] Figure 15 Cross-sectional view showing the case of induction heating of the ring-shaped component in the eighth embodiment.

[0039] Figure 16 Cross-sectional view showing the case of induction heating of the ring-shaped component in the ninth embodiment.

[0040] Figure 17 Cross-sectional view showing the case of induction heating of ring-shaped components of various shapes.

[0041] Figure 18 Schematic configuration diagram of a motor using a bearing as a ring-shaped component. Detailed implementation mode

[0042] [First Embodiment]

[0043] Utilize Figures 1 to 6 The first embodiment of the present invention will be described. In this embodiment, for example, as Figure 1 shown, the outer ring 2 of the radial ball bearing 1 is heated by an induction heating method and is subjected to quenching treatment and tempering treatment. In this case, the outer ring 2 corresponds to the ring-shaped component. Below, first, the structure of the radial ball bearing 1 will be described, and then the manufacturing method of the outer ring 2 including quenching treatment and tempering treatment will be described.

[0044] In addition, in the following description, unless otherwise specified, the axial direction, the radial direction, and the circumferential direction represent the axial direction, the radial direction, and the circumferential direction of the radial ball bearing 1. The axial direction, the radial direction, and the circumferential direction of the radial ball bearing 1 are the same as those of the outer ring 2 and are the same as those of the inner ring 3. Regarding the radial ball bearing 1, the axial side (the first shaft ends 31, 41) refers to Figure 1 the right side of Figure 2 and Figure 1 the upper side of Figure 2 , and the other axial side (the second shaft ends 32, 42) refers to

[0045] <Structure of the Radial Ball Bearing 1>

[0046] The radial ball bearing 1 is composed of a single-row angular contact ball bearing and includes an outer ring 2, an inner ring 3, and a plurality of rolling elements 4.

[0047] In one example, the outer ring 2 is made of a hard alloy such as bearing steel or carburizing steel. In other examples, the outer ring 2 is made of other materials.

[0048] The outer ring 2 has an outer ring raceway 5 for the rolling elements 4 at the axial intermediate portion of the inner circumferential surface (inner surface). In one example, the outer ring raceway 5 has an arc-shaped generatrix shape with a diameter increasing as it approaches the axial one side (the first shaft end 31). Further, the outer ring 2 has an inclined surface portion 6 in a conical concave shape at the portion of the inner circumferential surface adjacent to the first shaft end 31 of the outer ring raceway 5, which is inclined in the direction where the inner diameter increases as it approaches the first shaft end 31. In addition, the outer ring 2 has a cylindrical surface portion 7 with an inner diameter that does not change axially at the portion of the inner circumferential surface adjacent to the axial other side (the second shaft end 32) of the outer ring raceway 5. Moreover, the outer ring 2 has chamfered portions 8a, 8b with an arc-shaped generatrix shape at both axial end portions of the inner circumferential surface.

[0049] The outer ring 2 has a cylindrical surface portion (flat surface) 9 with an outer diameter that does not change axially at the axial intermediate portion of the outer circumferential surface (outer surface), and has chamfered portions 10a, 10b with an arc-shaped generatrix shape at both axial end portions of the outer circumferential surface.

[0050] That is, the outer ring 2 as a whole has a radially decreasing thickness (thickness variation, wall structure) as it approaches the first shaft end 31 (except for the vicinity of the second shaft end 32 where the chamfered portion 8b is provided on the inner circumferential surface and the chamfered portion 10b is provided on the outer circumferential surface). The outer circumferential surface (outer surface) of the outer ring 2 has a flat surface with relatively small irregularities and the surface height is substantially the same with respect to the reference axis along the axial direction. The inner circumferential surface (inner surface) of the outer ring 2 has relatively large irregularities formed by the outer ring raceway 5 and the like, and the variation in the surface height with respect to the reference axis along the axial direction is large.

[0051] In one example, the inner ring 3 is made of a hard alloy such as bearing steel or carburizing steel. In other examples, the inner ring 3 is made of other materials. In addition, the inner ring 3 can be made of the same metal material as the outer ring 2 or can be made of a metal material different from the outer ring 2.

[0052] The inner ring 3 has an inner ring raceway 11 for the rolling elements 4 at the axial intermediate portion of the outer circumferential surface (outer surface). In one example, the inner ring raceway 11 has an arc-shaped generatrix shape with a diameter increasing as it approaches the axial other side (the second shaft end 42). Further, the inner ring 3 has an inclined surface portion 12 in a conical convex shape at the portion of the outer circumferential surface adjacent to the second shaft end 42 of the inner ring raceway 11, which is inclined in the direction where the outer diameter decreases as it approaches the second shaft end 42. In addition, the inner ring 3 has a cylindrical surface portion 13 with an outer diameter that does not change axially at the portion of the outer circumferential surface adjacent to the axial one side (the first shaft end 41) of the inner ring raceway 11. Moreover, the inner ring 3 has chamfered portions 14a, 14b with an arc-shaped generatrix shape at both axial end portions of the outer circumferential surface.

[0053] The inner ring 3 has a cylindrical surface portion (flat surface) 15 with an inner diameter that does not change axially at the axially intermediate portion of the inner circumferential surface (inner surface), and has chamfered portions 16a and 16b with an arc-shaped generatrix shape at the end portions on both axial sides of the inner circumferential surface.

[0054] That is, the entire inner ring 3 has a radially decreasing thickness (thickness variation, wall structure) as it approaches the second shaft end 42 (except for the vicinity of the first shaft end 41 having a chamfered portion 14a on the outer circumferential surface and a chamfered portion 16a on the inner circumferential surface). The inner circumferential surface (inner surface) of the inner ring 3 has a flat surface with relatively small irregularities and relatively consistent surface heights with respect to the reference axis along the axial direction. The outer circumferential surface (outer surface) of the inner ring 3 has relatively large irregularities caused by the inner ring raceway 11 and the like, and the variation in surface height with respect to the reference axis along the axial direction is large.

[0055] A plurality of rolling elements 4 are rotatably arranged between the outer ring raceway 5 and the inner ring raceway 11. In one example, each rolling element 4 is composed of a ball. In other examples, the rolling element 4 is composed of components other than balls such as rollers. Additionally, in one example, each rolling element 4 is composed of a hard alloy such as bearing steel or carburized steel or ceramics. In other examples, the rolling element 4 is composed of other materials.

[0056] <Manufacturing method of the outer ring 2>

[0057] When manufacturing the outer ring 2, first, forging is performed on a metal material to form the approximate shape of the outer ring 2, and then grinding is performed on the inner circumferential surface to form the outer ring raceway 5. Next, as Figure 6 shown, quenching treatment and tempering treatment are performed on the outer ring 2. Both the quenching treatment and the tempering treatment are carried out by heating the outer ring 2 to a target temperature, holding for a specified time, and then cooling.

[0058] Induction heating of the outer ring 2 is performed by generating eddy currents inside the outer ring 2 using an induction heating coil, thereby heating the outer ring 2 during the quenching treatment and the tempering treatment.

[0059] As Figure 2As shown, the induction heating device 200 includes an inner coil (inner induction coil, inner diameter side induction heating coil, inner coil) 17, an outer coil (outer diameter side induction heating coil, outer induction coil, outer coil) 18, and a power supply device 201 that supplies high-frequency current to the induction coils 17 and 18. In addition, the induction heating device 200 can include at least one of a support device 202 that supports a heating object (ring-shaped component, workpiece), a transfer device 203 that transfers the ring-shaped component, a cooling device 204 that cools the ring-shaped component, a sensor 205 that detects the temperature of the ring-shaped component, an electrical matching device 206, and a control unit 207. The induction heating device 200 can independently control the supply outputs (such as current values) to the induction coils 17 and 18 separately. In one example, the induction heating device 200 can independently control the timing of supplying current to the induction coil 17 and the timing of supplying current to the induction coil 18 separately. Additionally, in one example, the induction heating device 200 can independently control the currents (output values) for the induction coils 17 and 18 separately. Also, in one example, the induction heating device 200 can independently control the output times (heating times) for the induction coils 17 and 18 separately. In one example, the induction heating device 200 can independently control the relative positional relationship between the induction coils 17 and 18 and the ring-shaped component. Furthermore, the induction heating device 200 can also control a part of the above controls non-independently.

[0060] In the present embodiment, the method of induction heating the outer ring 2 includes an inner heating process (inner diameter heating process, inner surface heating process, first heating process) and an outer heating process (outer diameter heating process, outer surface heating process, second heating process) that are implemented independently of each other. In this example, the process of induction heating the outer ring 2 is implemented in the order of the inner heating process (first heating process) and the outer heating process (second heating process). The induction heating device 200 includes a first mode in which current is supplied to one coil to inductively heat the ring-shaped component so that at least a part of the ring-shaped component reaches a first target temperature, and a second mode in which current is supplied to the other coil to inductively heat the ring-shaped component so that at least a part of the ring-shaped component reaches a second target temperature higher than the first target temperature.

[0061] In the inner heating process, as Figure 3As shown in (A) of , with the inner coil (inner diameter side induction heating coil, inner coil) 17 disposed radially inside the outer ring 2 and no induction coil (induction heating coil, substantial coil) disposed radially outside the outer ring 2, the outer ring 2 is induction heated from the radial inside by energizing the induction coil 17. With no substantial coil disposed radially outside the outer ring 2, the outer ring 2 is induction heated by the induction coil (inner coil) 17 disposed radially inside the outer ring 2. That is, by energizing the inner coil 17 disposed radially inside the outer ring 2, eddy currents are generated in the radially inner part of the outer ring 2, and the outer ring 2 is heated from the radial inside.

[0062] In one example, the inner coil 17 has a wire with a constant inner diameter wound in a spiral shape in the axial direction, or a conductive material with a constant inner diameter in the axial direction bent and formed into a ring shape. In other examples, the inner coil 17 can have a configuration other than the above.

[0063] In the present embodiment, the inner coil 17 used in the inner heating process is disposed adjacent to the inner circumferential surface of the outer ring 2 such that the outer surface of the induction coil 17 faces the inner surface of the outer ring 2. In one example, the outer circumferential surface (outer surface) of the inner coil 17 is brought close to and opposed to the cylindrical surface portion 7 provided on the inner circumferential surface of the outer ring 2. The distance between the outer circumferential surface of the inner coil 17 and the cylindrical surface portion 7 provided on the inner circumferential surface of the outer ring 2 is set such that eddy currents can be generated in the radially inner part of the outer ring 2, and can be set to about 1% to 30% of the inner diameter of the cylindrical surface portion 7 of the outer ring 2, for example. The above values are for example only and are not limited to the above values.

[0064] After the outer ring 2 is heated for a specified time in the inner diameter heating process, it is transported to the outer diameter heating process.

[0065] In the outer heating process, as Figure 3 shown in (B) of , with the outer coil (outer diameter side induction heating coil, outer coil) 18 disposed radially outside the outer ring 2 and no induction coil (induction heating coil, substantial coil) disposed radially inside the outer ring 2, the outer ring 2 is induction heated from the radial outside by energizing the outer coil 18. With no substantial coil disposed radially inside the outer ring 2, the outer ring 2 is induction heated by the induction coil (outer coil) 18 disposed radially outside the outer ring 2. That is, by energizing the outer coil 18 disposed radially outside the outer ring 2, eddy currents are generated in the radially outer part of the outer ring 2, and the outer ring 2 is heated from the radial outside.

[0066] In one example, the outer coil 18 has a wire with a constant outer diameter wound in a spiral shape axially, or a conductive material bent into a ring shape with a constant outer diameter axially. In other examples, the outer coil 18 can have a configuration other than the above.

[0067] In the present embodiment, the outer coil 18 used in the outer heating process is arranged adjacent to the outer peripheral surface of the outer ring 2 so that the inner surface of the induction coil 18 faces the outer surface of the outer ring 2. In one example, the inner peripheral surface (inner surface) of the outer coil 18 is brought close to and opposed to the outer peripheral surface (outer surface) of the outer ring 2. The distance between the inner peripheral surface of the outer coil 18 and the outer peripheral surface of the outer ring 2 is set such that eddy currents can be generated in the radially outer portion of the outer ring 2, and can be set to about 1% to 30% of the outer diameter of the outer ring 2, for example. The above values are for example only and are not limited to the above values.

[0068] For example, in the quenching treatment of the outer ring 2, the inner surface heating process and the outer surface heating process are sequentially performed on the outer ring 2 to heat the outer ring 2 to a quenching temperature in the range of 800°C to 1000°C. Then, the outer ring 2 is placed in an induction heating device and held at the quenching temperature for 1 second to 30 seconds, and then immersed in quenching oil to perform oil cooling or the like to rapidly cool to room temperature. The above values or steps are for example only and are not limited to the above values or steps.

[0069] For example, in the tempering treatment of the outer ring 2, the inner heating process and the outer heating process are sequentially performed on the outer ring 2 to heat the outer ring 2 to a tempering temperature in the range of 150°C to 300°C. Then, the outer ring 2 is placed in an induction heating device and held at the tempering temperature for 1 second to 30 seconds, and then naturally cooled to room temperature. The above values or steps are for example only and are not limited to the above values or steps.

[0070] After performing the quenching treatment and the tempering treatment on the outer ring 2, if necessary, finish machining such as grinding is performed on the outer ring track 5 to complete the outer ring 2.

[0071] Here, in the present embodiment, the effective lengths of the induction coils 17 and 18 (the length range of the coils in the axial direction that contributes to induction heating (the distance from the first effective heating end 51 to the second effective heating end 52 in the axial direction)) are set to be larger than the axial length of the annular member (workpiece, outer ring 2, etc.) (the distance from the first axial end 31 to the second axial end 32 in the axial direction). For example, the effective lengths of the induction coils 17 and 18 are set to be 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, 200%, 210%, 220%, 230%, 240%, 250%, 260%, 270%, 280%, 290%, or 300% or more of the axial length of the outer ring 2. Since the effective lengths of the induction coils 17 and 18 are 110% or more of the axial length of the annular member, a part of the magnetic field wraps around the axial end faces of the outer ring 2, etc., whereby the heating range in the annular member expands, and heating uniformity can be achieved for the entire annular member. For example, in addition to the inner surface or the outer surface of the annular member, heating is also performed from the axial end face toward the inside. Since the effective lengths of the induction coils 17 and 18 are 200% or more of the axial length of the annular member, the allowable degree for shape changes or position deviations of the annular member is alleviated, and the versatility of the induction coils 17 and 18 is improved. For example, the effective lengths of the induction coils 17 and 18 are set to be 200% or more of the average axial length of the annular members in a specified batch (a batch including various annular members (outer rings, etc.) with different shapes). In this case, one type of induction coils 17 and 18 is used to perform heat treatment on a plurality of annular members with various shapes. The reduction in the replacement frequency of the induction coils 17 and 18 and the commonality of the heating conditions are beneficial to the improvement of productivity.

[0072] In one example, as Figure 4 (A) shown, the positional relationship between the induction coil and the annular member is set such that the axial center position of the annular member (outer ring 2, etc.) is located at the same position as the center position of the axial effective length of the induction coil (induction coil 17, etc.). In this case, the protruding length (protrusion height) H1 of the induction coil (induction coil 17, etc.) near the first axial end of the annular member (the first axial end 31 of the outer ring 2, etc.) is the same as the protruding length (protrusion height) H2 of the induction coil near the second axial end (the second axial end 32 of the outer ring 2, etc.). That is, the distance H1 between the first axial end of the annular member (the first axial end 31 of the outer ring 2, etc.) and the first axial end of the induction coil (the first axial end 51 of the induction coil 17, etc.) in the axial direction is the same as the distance H2 between the second axial end of the annular member (the second axial end 32 of the outer ring 2, etc.) and the second axial end of the induction coil (the second axial end 52 of the induction coil 17, etc.) in the axial direction. In other examples, as Figure 4As shown in (B), the distance H2 is set to be larger than the distance H1. That is, the positional relationship between the induction coil and the ring-shaped member is set such that the axial center position of the ring-shaped member (such as the outer ring 2) is located at a position different from the center position of the axial effective length of the induction coil (such as the induction coil 17). In Figure 4 In the example of (B), the thickness of the portion near the second axial end (such as the second axial end 32 of the outer ring 2) of the ring-shaped member is greater than the thickness of the ring-shaped member in the portion near the first axial end (such as the first axial end 31 of the outer ring 2). Since the extension length (protrusion height) H2 of the induction coil near the second axial end with a larger thickness is set to be larger, uniform heating can be achieved for the entire ring-shaped member with a thickness variation. These can also be similarly applied to the case where the induction coil is arranged outside the ring-shaped member. Since the effective lengths of the induction coils 17 and 18 are larger than the axial length of the ring-shaped member, the allowable level for changes in the relative positional relationship between the induction coil and the ring-shaped member is relaxed.

[0073] Returning to Figure 3 , in the present embodiment, when induction heating the outer ring 2 for quenching treatment or tempering treatment, the inner heating process and the outer heating process are independently implemented. In a state where no substantial coil is arranged outside the radial direction of the outer ring 2, the outer ring 2 is heated from the inside. In the case where no substantial coil is arranged inside the radial direction of the outer ring 2, the outer ring 2 is heated from the outside. Accordingly, the heating conditions in the inner heating process of induction heating the outer ring 2 from the radial inside and the heating conditions in the outer heating process of induction heating the outer ring 2 from the radial outside can be independently controlled. Therefore, the heating state of the outer ring 2 can be easily controlled. That is, by appropriately setting the heating conditions in the inner heating process and the heating conditions in the outer heating process respectively, the entire outer ring 2 can be heated substantially uniformly and efficiently. Through the combination of the separate arrangement of the induction coil with respect to the ring-shaped member (such as the outer ring 2) and the setting of the induction coil length, two advantages of improving heating efficiency and productivity can be obtained. Such advantages can be achieved for multiple heating processes and single heating processes respectively.

[0074] In addition, as heating conditions, examples can include the current value supplied to the induction coils 17 and 18 (∝ the output of the induction heating coils 17 and 18), the heating time, and the positional relationship between the outer ring 2 and the induction coils 17 and 18, etc.

[0075] In the present embodiment, the induction heating method includes: a step of preparing an inner coil 17 disposed radially inside the outer ring 2 and an outer coil 18 disposed radially outside the outer ring 2; a first heating step of supplying current to one of the inner coil 17 and the outer coil 18 to inductively heat the outer ring 2 so that at least a part of the outer ring 2 reaches a first target temperature; and a second heating step of, after the first heating step, supplying current to the other of the inner coil 17 and the outer coil 18 to inductively heat the outer ring 2 so that at least a part of the outer ring 2 reaches a second target temperature higher than the first target temperature. In the present embodiment, one coil (inner coil 17) used in the first heating step is disposed adjacent to the inner surface (first surface) of the outer ring 2 where the surface height changes greatly between the inner surface and the outer surface, and the other coil (outer coil 18) used in the second heating step is disposed adjacent to the outer surface (second surface) of the outer ring 2 where the surface height is relatively uniform between the inner surface and the outer surface. In a state where only one of the inner coil 17 and the outer coil 18 is disposed adjacent to the outer ring 2, at least one of the first heating step and the second heating step is implemented. In the present embodiment, the inner heating step and the outer heating step are implemented in sequence.

[0076] Here, generally, the following problems may occur when heating the outer ring or inner ring of a bearing by induction heating. For example, the outer ring of a rolling bearing has an outer ring raceway on its inner circumferential surface. In the case where an induction coil is disposed radially inside the outer ring, the distance between the inner circumferential surface of the outer ring and the induction coil varies according to the axial position. Therefore, when current is supplied to the induction coil, eddy currents concentrate in the part of the inner circumferential surface that is close to the induction coil, and this part is easily inductively heated intensively. The part that is far from the induction coil is heated by heat transfer from the part of the inner circumferential surface that is close to the induction coil. When the heating rate varies greatly according to the axial position of the outer ring, it is difficult to uniformly heat the entire outer ring. In the case where quenching treatment and tempering treatment are implemented in a state where the temperature inside the outer ring is non-uniform, there may be a failure to meet the required quality due to, for example, non-uniform thickness of the hardened layer formed on the surface of the outer ring. To avoid such problems, a method of reducing the output of the induction coil by reducing the value of the current supplied to the induction coil and extending the heating time of the outer ring is considered. Although this method can suppress the difference in the heating rate of the outer ring caused by the axial position to a small extent, it results in a reduction in productivity and is therefore not preferred.

[0077] In the present embodiment, in the first heating step (inner heating step), the outer ring 2 is heated by the induction coil 17 disposed opposite to the inner surface of the outer ring 2 where the surface height changes greatly, and in the subsequent second heating step (outer heating step), the outer ring 2 is heated by the induction coil 18 disposed opposite to the outer surface of the outer ring 2 where the surface height is relatively uniform. For example, as Figure 5As shown, in the first heating process (inner heating process), a part (P i2 ) on the inner surface side of the outer ring 2 has its temperature rise earlier and reach the first target temperature T1. At this time, the temperature of other parts is lower than the first target temperature. Heat from the relatively high-temperature part (P i2 ) of the outer ring 2 is transferred to other parts. In the second heating process (outer heating process), the outer ring 2 is heated from the outside. At a certain moment, most of the outer ring 2 reaches a temperature close to the second target temperature T2. In the induction heating of the outer ring 2 with a large thickness variation, the whole outer ring 2 is heated in a short time, and the difference in the temperature rise rate of the outer ring 2 is suppressed to be small.

[0078] In the inner heating process (first heating process), by increasing the current value supplied to the inner coil 17 to increase the output of the inner coil 17, as Figure 5 schematically shown, it is possible to rapidly raise the temperature of the inner peripheral surface (P i2 (refer to Figure 3 (A))) of the end part of the second shaft end with a large radial thickness in the outer ring 2 to near the first target temperature.

[0079] In the inner heating process, the temperature rise amount of the end part P i2 of the second shaft end on the inner peripheral surface of the outer ring 2, which is close to the inner coil 17, is larger than that of the end part P i1 of the first shaft end, which is far from the inner coil 17. On the other hand, the temperature rise amount of the end part P O2 of the second shaft end on the outer peripheral surface of the outer ring 2 is of the same order as that of the end part P O1 of the first shaft end on the outer peripheral surface of the outer ring 2.

[0080] In the outer heating process, the outer ring 2 is heated from a flat surface with relatively uniform surface height (the radially outer part with a constant outer diameter except for the end parts on both axial sides). By adjusting the current value supplied to the outer coil 18, the output and heating time are adjusted. Accordingly, as Figure 5 schematically shown, the whole outer ring 2 is heated approximately uniformly to near the target temperature (second target temperature). In other words, the temperatures of each part of the outer ring 2 rise to the target temperature at almost the same time.

[0081] In addition, as described later, the process of inductively heating the outer ring 2 can also be carried out in the order of the outer heating process and the inner heating process.

[0082] The heating conditions in the inner heating process and the heating conditions in the outer heating process can be determined in advance through experiments, simulation calculations, etc. The heating time in the outer heating process relative to the heating time in the inner heating process also depends on the radial thickness of the outer ring 2, etc., but can be set to, for example, 50% to 200%, preferably 80% to 120%. The current value supplied to the outer coil 18 in the outer heating process relative to the current value supplied to the inner coil 17 in the inner heating process also depends on the radial thickness of the outer ring 2, etc., but can be set to, for example, 50% to 200%, preferably 80% to 120%.

[0083] In one example, in the inner heating process, the outer peripheral surface of the inner coil 17 is disposed close to and opposite the cylindrical surface portion 7 provided on the inner peripheral surface of the outer ring 2, and in the outer heating process, the inner peripheral surface of the outer coil 18 is disposed close to and opposite the outer peripheral surface of the outer ring 2. In addition, as the inner coil 17 and the outer coil 18, a combination corresponding to a specific model of the outer ring 2 is used. In this case, in the inner heating process, heating from the radially inner side of the outer ring 2 is efficiently performed, and in the outer heating process, heating from the radially outer side of the outer ring 2 is efficiently performed. Accordingly, the time required to heat the outer ring 2 to the target temperature is suppressed to be short. In this example, in mass production of the same model of the outer ring 2, production efficiency is satisfactorily ensured.

[0084] In other examples, a relatively large radial gap is provided in a portion between the outer peripheral surface of the inner coil 17 and the cylindrical surface portion 7 provided on the inner peripheral surface of the outer ring 2 in the inner heating process, and / or in a portion between the inner peripheral surface of the outer coil 18 and the cylindrical surface portion 9 provided on the outer peripheral surface of the outer ring 2 in the outer heating process. For example, as shown in (A) of Figure 8 an inner diameter side induction coil 17 is used in which the ratio of the outer diameter to the inner diameter of the cylindrical surface portion 7 is smaller than that of the inner diameter side induction coil 17 in the first example shown in (A) of Figure 3 There is a radial gap larger than the gap in the manner shown in (A) of Figure 3 in a portion between the outer peripheral surface of the inner coil 17 and the cylindrical surface portion 7. In addition, as shown in (B) of Figure 7 an outer diameter side induction coil 18 is used in which the ratio of the inner diameter to the outer diameter of the cylindrical surface portion 9 is larger than that of the outer diameter side induction coil 18 in the first example shown in (B) of Figure 3 There is a radial gap larger than the gap in the manner shown in (B) of Figure 3 in a portion between the inner peripheral surface of the outer coil 18 and the cylindrical surface portion 9.

[0085] In this case, by using the same combination of the inner coil 17 and the outer coil 18, induction heating can be performed on a plurality of outer rings having different outer diameters and inner diameters. For example, in Figure 7In the inner heating process shown in (A), the outer peripheral surface of the inner coil 17 faces the cylindrical surface portion 7 provided on the inner peripheral surface of the outer ring 2a in a closely opposed manner. In Figure 7 In the outer heating process shown in (B), there is a large radial gap in the portion between the inner peripheral surface of the outer coil 18 and the outer peripheral surface of the outer ring 2a. The distance between the inner peripheral surface of the outer coil 18 and the outer peripheral surface of the outer ring 2a is not particularly limited as long as it can generate eddy currents in the radially outer portion of the outer ring 2a by energizing the outer coil 18. For example, it can be set to about 1% to 30% of the outer diameter of the outer ring 2a at maximum.

[0086] In Figure 7 In the example, there is a large radial gap in the portion between the inner peripheral surface of the outer coil 18 and the outer peripheral surface of the outer ring 2a in the outer heating process. However, in the outer heating process, by increasing the current value supplied to the outer coil 18 to increase the output of the outer coil 18, it is possible to prevent an excessive increase in the time required to heat the outer ring 2a to the target temperature.

[0087] In Figure 8 In the example shown, the inner coil 17 and the outer coil 18 in the same combination as Figure 7 are used to perform induction heating on the outer ring 2b having a larger outer diameter and inner diameter ratio than Figure 7 the example. In Figure 8 In the inner heating process shown in (A), there is a large radial gap in the portion between the outer peripheral surface of the inner coil 17 and the cylindrical surface portion 7 provided on the inner peripheral surface of the outer ring 2b. In Figure 8 In the outer heating process shown in (B), the inner peripheral surface of the outer coil 18 faces the outer peripheral surface of the outer ring 2a in a closely opposed manner. The distance between the outer peripheral surface of the inner coil 17 and the inner peripheral surface of the outer ring 2b is not particularly limited as long as it can generate eddy currents in the radially inner portion of the outer ring 2b. For example, it can be set to about 1% to 30% of the inner diameter of the outer ring 2b at maximum.

[0088] In Figure 8 In the example, there is a large radial gap in the portion between the outer peripheral surface of the inner coil 17 and the inner peripheral surface of the outer ring 2b in the inner heating process. In the inner heating process, by increasing the current value supplied to the inner coil 17 to increase the output of the inner coil 17, it is possible to prevent an excessive increase in the time required to heat the outer ring 2b to the target temperature.

[0089] In Figure 7 and Figure 8 In the examples, by appropriately setting the heating conditions in the outer heating process and the heating conditions in the inner heating process respectively, it is possible to heat the entire outer rings 2a and 2b substantially uniformly and efficiently.

[0090] In Figure 7 andFigure 8 In the example, the heating conditions are set to allow a relatively large radial gap to exist between the outer peripheral surface of the inner coil 17 and the cylindrical surface portion 7 provided on the inner peripheral surface of the outer ring 2 in the inner heating process and / or between the inner peripheral surface of the outer coil 18 and the outer peripheral surface of the outer ring 2 in the outer heating process. By using the same combination of the inner coil 17 and the outer coil 18, induction heating can be performed on a variety of outer rings with different outer diameters and inner diameters. It is not necessary to replace the inner coil 17 and the outer coil 18 every time the outer diameter and inner diameter of the outer ring change. For example, it is particularly preferably applicable to a production line for outer rings in small batches of multiple varieties. Since it is not necessary to prepare multiple combinations of the inner coil 17 and the outer coil 18, the replacement operation of the inner coil 17 and the outer coil 18 is omitted, and the production efficiency is improved.

[0091] In addition, in the inner heating process, an induction heating coil is not arranged on the radial outer side of the outer ring 2, and in the outer heating process, an induction heating coil is not arranged on the radial inner side of the outer ring 2. Therefore, the heating conditions in the inner heating process and the heating conditions in the outer heating process can be stably controlled.

[0092] For example, in the inner heating process, when an induction heating coil not supplied with current is arranged on the radial outer side of the outer ring 2, current may flow through the induction heating coil arranged on the radial outer side of the outer ring 2 due to electromagnetic induction when the inner coil 17 is energized. When the radial outer side portion of the outer ring 2 is accidentally heated, it is difficult to stably control the heating conditions. In the present embodiment, in the inner heating process, since an induction heating coil is not arranged on the radial outer side of the outer ring 2, the heating conditions in the inner heating process can be stably controlled.

[0093] In the present embodiment, the case where the outer ring 2 (as a ring-shaped member) of the radial ball bearing 1, which is a single-row angular contact ball bearing, is heated by an induction heating method to perform quenching treatment and tempering treatment has been described.

[0094] However, the ring-shaped member is not limited to the outer ring of a single-row angular contact ball bearing. Any ring-shaped member can be used as the ring-shaped member. For example, as the ring-shaped member, the outer ring of a single-row deep groove ball bearing, a roller bearing, or a tapered roller bearing can be applied, or as shown in the fourth to sixth embodiments described later, the inner ring of a rolling bearing can be applied. Alternatively, as the ring-shaped member, the outer ring or inner ring of a multi-row rolling bearing can be applied. In addition, as the ring-shaped member, a sliding bearing can also be applied.

[0095] The heat treatment using the induction heating method is not limited to quenching treatment and tempering treatment. As the heat treatment, annealing treatment or normalizing treatment can also be applied.

[0096] In addition, as heat treatment using an induction heating method, it can be applied to quenching, tempering, annealing, and / or normalizing of annular components included in a vehicle or a mechanical device.

[0097] [Second Embodiment]

[0098] Refer to Figure 9 to describe the second embodiment of the present invention. In this embodiment, the process of induction heating the outer ring 2 is carried out in the order of the outer heating process shown in (A) of Figure 9 and the inner heating process shown in (B) of Figure 9 .

[0099] In this embodiment, similarly to the first embodiment, by appropriately setting the heating conditions in the outer heating process and the heating conditions in the inner heating process respectively, it is possible to heat the entire outer ring 2 substantially uniformly and efficiently.

[0100] In this embodiment, in the first heating process (outer heating process), the outer ring 2 is heated by the induction coil 18 disposed opposite to the outer peripheral surface of the outer ring 2 with a relatively consistent surface height. In the subsequent second heating process (inner heating process), the outer ring 2 is heated by the induction coil 17 disposed opposite to the inner peripheral surface of the outer ring 2 with a relatively large change in surface height. For example, in Figure 9 the first heating process (outer heating process) shown in (A) of i2 , the temperature of a part on the outer surface side of the outer ring 2 reaches the first target temperature. On the other hand, heat is difficult to transfer to a part (P i2 ) on the inner surface side of the outer ring 2 located at a position far from the outer surface, and the temperature is lower than that of other parts.

[0101] Next, in Figure 9 the second heating process (inner heating process) shown in (B) of i2 , the part with a lower temperature (P i2 ) is easily heated, and the temperature of this part (P i2 ) rises earlier. As a result, at a certain moment, most of the outer ring 2 reaches a temperature close to the second target temperature T2. In the induction heating of the outer ring 2 with a large thickness variation, the entire outer ring 2 is heated in a short time, and the difference in the temperature rise rate of the outer ring 2 is suppressed to be small. The configurations and effects of other parts are the same as those of the first embodiment.

[0102] [Third Embodiment]

[0103] Refer to Figure 10 to describe the third embodiment of the present invention. In this embodiment, the process of induction heating the outer ring 2 is carried out in the order of the inner heating process shown in (A) of Figure 10 and Figure 10After the sequential execution of the outer heating process shown in (B), it further includes Figure 10 a reheating process of induction heating the outer ring 2 from the radially inner side as shown in (C).

[0104] In the reheating process, a reheating inner coil (reheating inner diameter side induction heating coil, reheating inner induction coil, reheating inner coil) 19 is arranged on the radially inner side of the outer ring 2, and in a state where no induction heating coil is arranged on the radially outer side of the outer ring 2, the outer ring 2 is induction heated from the radially inner side by energizing the inner coil 19. In the present embodiment, the outer peripheral surface of the inner coil 19 is disposed close to and opposite to the cylindrical surface portion 7 provided on the inner peripheral surface of the outer ring 2.

[0105] It is possible to make the positional relationship in the radial direction between the outer ring 2 and the inner coil 19 in the reheating process the same as or different from the positional relationship in the radial direction between the outer ring 2 and the inner coil 17 in the inner heating process. In addition, as the inner coil 19, the inner coil 17 used in the inner heating process can also be used.

[0106] In the present embodiment, by appropriately setting the heating conditions in the inner heating process, the heating conditions in the outer heating process, and the heating conditions in the reheating process respectively, the entire outer ring 2 can be heated substantially uniformly and efficiently.

[0107] In the present embodiment, the process of induction heating the outer ring 2, after being carried out in the order of the inner heating process and the outer heating process, further includes a reheating process of induction heating the outer ring 2 from the radially inner side. Therefore, the entire outer ring 2 can be heated more reliably and substantially uniformly.

[0108] That is, in the induction heating method of the first embodiment, after heating the outer ring 2 from the radially inner side in the inner heating process, during the transfer to the outer heating process, the temperature of the radially inner part of the outer ring 2 may drop. In this case, even if the outer ring 2 is heated from the radially outer side in the outer heating process, the radially inner part of the outer ring 2 may not be heated up to the target temperature.

[0109] In the present embodiment, after being carried out in the order of the inner heating process and the outer heating process, a reheating process of induction heating the outer ring 2 from the radially inner side is carried out. Even when the temperature of the radially inner part of the outer ring 2 drops during the transfer between processes, it can be heated up to the target temperature by reheating this part, and the temperature of the entire outer ring 2 can be adjusted substantially uniformly. The configurations and functions of other parts are the same as those of the first embodiment.

[0110] [Fourth Embodiment]

[0111] Reference Figure 11 Describe the fourth embodiment of the present invention. In this embodiment, induction heating is used to Figure 1 heat the inner ring 3 of the centripetal rolling bearing 1 shown in the figure.

[0112] In this embodiment, the process of induction heating the inner ring 3 includes an outer heating process and an inner heating process that are independently implemented. In this embodiment, the process of induction heating the inner ring 3 is carried out in the order of the outer heating process and the inner heating process.

[0113] In the outer heating process, as shown in (A) of Figure 11 , with the outer coil 18a arranged on the radial outer side of the inner ring 3 and no induction heating coil arranged on the radial inner side of the inner ring 3, the inner ring 3 is induction heated from the radial outer side by energizing the outer coil 18a.

[0114] In this embodiment, the inner peripheral surface of the outer coil 18a is opposed to the cylindrical surface portion 13 provided on the outer peripheral surface of the inner ring 3 in a close proximity. The distance between the inner peripheral surface of the outer coil 18a and the cylindrical surface portion 13 provided on the outer peripheral surface of the inner ring 3 is not particularly limited as long as it can generate eddy currents in the radially outer portion of the inner ring 3, and can be set to about 1% to 30% of the outer diameter of the cylindrical surface portion 13 of the inner ring 3, for example.

[0115] In the inner heating process, as shown in (B) of Figure 11 , with the inner coil 17a arranged on the radial inner side of the inner ring 3 and no induction coil arranged on the radial outer side of the inner ring 3, the inner ring 3 is induction heated from the radial inner side by energizing the inner coil 17a.

[0116] In this embodiment, the outer peripheral surface of the inner coil 17a is opposed to the inner peripheral surface of the inner ring 3 in a close proximity. The distance between the outer peripheral surface of the inner coil 17a and the inner peripheral surface of the inner ring 3 is not particularly limited as long as it can generate eddy currents in the radially inner portion of the inner ring 3, and can be set to about 1% to 30% of the inner diameter of the inner ring 3, for example.

[0117] In this embodiment, by appropriately setting the heating conditions in the outer heating process and the heating conditions in the inner heating process respectively, the entire outer ring 2 can be heated substantially uniformly and efficiently.

[0118] In this embodiment, the outer heating process and the inner heating process are carried out in sequence.

[0119] In the outer heating process, by increasing the output of the outer coil 18a, the temperature of the outer peripheral surface of the end portion of the first shaft end having a large radial thickness in the inner ring 3 is rapidly raised to near the target temperature.

[0120] Next, in the inner heating process, the output and heating time are adjusted by adjusting the current value supplied to the inner coil 17a, and the inner ring 3 is heated from the radially inner portion having a constant outer diameter except for the end portions on both axial sides. Accordingly, the entire inner ring 3 can be heated to the target temperature substantially uniformly. In other words, the temperature of each part of the inner ring 3 can rise to the target temperature at almost the same time. The configurations and effects of other parts are the same as those of the first embodiment.

[0121] [Fifth Embodiment]

[0122] Refer to Figure 12 to describe the fifth embodiment of the present invention. In this embodiment, the process of induction heating the inner ring 3 is performed in the order of the inner heating process shown in (A) of Figure 12 and the outer heating process shown in (B) of Figure 12 .

[0123] In this embodiment, by appropriately setting the heating conditions in the inner heating process and the heating conditions in the outer heating process, the entire inner ring 3 can also be heated substantially uniformly and efficiently. The configurations and effects of other parts are the same as those of the first embodiment and the fourth embodiment.

[0124] [Sixth Embodiment]

[0125] Refer to Figure 13 to describe the sixth embodiment of the present invention. In this embodiment, the process of induction heating the inner ring 3 is performed in the order of the outer heating process shown in (A) of Figure 13 and the inner heating process shown in (B) of Figure 13 , and then includes Figure 13 a reheating process of induction heating the inner ring 3 from the radially outer side shown in (C) of

[0126] In the reheating process, as shown in (C) of Figure 13 , with the reheating outer coil (reheating outer diameter side induction heating coil, reheating outer induction coil, reheating outer coil) 20 arranged on the radially outer side of the inner ring 3 and no induction coil arranged on the radially inner side of the inner ring 3, the inner ring 3 is induction heated from the radially outer side by energizing the outer coil 20. In this embodiment, the inner peripheral surface of the outer coil 20 is disposed close to and opposite to the cylindrical surface portion 13 provided on the outer peripheral surface of the inner ring 3.

[0127] In this embodiment, by appropriately setting the heating conditions in the outer heating process, the heating conditions in the inner heating process, and the heating conditions in the reheating process, the entire inner ring 3 can be heated substantially uniformly and efficiently.

[0128] In the present embodiment, after the steps of induction heating the inner ring 3 are carried out in the order of the outer heating step and the inner heating step, a reheating step of induction heating the inner ring 3 from the radially outer side is further included, so that the entire inner ring 3 can be heated more reliably and substantially uniformly.

[0129] In the present embodiment, after the steps of the outer heating step and the inner heating step are carried out in this order, a reheating step of induction heating the inner ring 3 from the radially outer side is carried out. During the transfer from the outer heating step to the inner heating step, even if the temperature of the radially outer portion of the inner ring 3 drops, it can be heated up to the target temperature by reheating this portion, and the temperature of the entire inner ring 3 can be adjusted to be substantially uniform. The configurations and functions of the other parts are the same as those of the first embodiment, the third embodiment, and the fourth embodiment.

[0130] [Seventh Embodiment]

[0131] Refer to Figure 14 to describe the seventh embodiment of the present invention.

[0132] In the present embodiment, as Figure 14 shown in the (A) part and (B) part of, the effective lengths of the induction coils 17 and 18 are of the same order as the axial length of the annular member 30. When the axial length of the annular member 30 is the same as the effective lengths of the induction coils 17 and 18, the magnetic field is difficult to turn toward the axial end faces of the annular member 30, and it may be difficult to heat to the radially inner part at the axial end faces. In this case, the annular member 30 is additionally heated by a reheating step as needed. On the other hand, when the difference in the radial thickness in the annular member 30 is small, the influence of the magnetic field turning in is small, and relatively uniform heating can be carried out without setting a reheating step.

[0133] In the present embodiment, a current is supplied to the inner coil 17, and a first heating step of induction heating the annular member 30 is carried out so that at least a part of the annular member 30 reaches a first target temperature. Then, a current is supplied to the outer coil 18, and a second heating step of induction heating the annular member 30 is carried out so that at least a part of the annular member 30 reaches a second target temperature higher than the first target temperature. The configurations and functions of the other parts are the same as those of the above embodiments.

[0134] [Eighth Embodiment]

[0135] Refer to Figure 15 to describe the eighth embodiment of the present invention.

[0136] In the present embodiment, as Figure 15As shown in parts (A) and (B), the effective lengths of the induction coils 17 and 18 are greater than the axial length of the annular member 30. For example, the effective length of the induction coil is set to 110%, 120%, 130%, 140%, or 150% or more of the axial length of the annular member 30. When the effective lengths of the induction coils 17 and 18 are greater than the axial length of the annular member 30, the magnetic field easily turns toward the axial end faces of the annular member 30, and heat is also applied to the inside of the annular member 30 at the axial end faces. As a result, the entire cross-section of the annular member 30 is easily heated evenly. The configurations and effects of other parts are the same as those of the above-described embodiment.

[0137] [Ninth Embodiment]

[0138] Refer to Figure 16 to describe the ninth embodiment of the present invention.

[0139] In the present embodiment, as Figure 16 shown in parts (A), (B), (C), and (D), the effective lengths of the induction coils 17 and 18 are greater than the axial length of the annular member 30. For example, the effective length of the induction coil is set to 160%, 170%, 180%, 190%, 200%, 210%, 220%, 230%, 240%, 250%, 260%, 270%, 280%, 290%, or 300% or more of the axial length of the annular member 30. In the present embodiment, as in the eighth embodiment, the magnetic field easily turns toward the axial end faces of the annular member 30, and heat is also applied to the inside of the annular member 30 at the axial end faces. As a result, the entire cross-section of the annular member 30 is easily heated evenly.

[0140] In the present embodiment, the dimensional difference between the effective lengths of the induction coils 17 and 18 and the axial length of the annular member 30 is larger than that of the eighth embodiment. By setting the current value supplied to the induction coils 17 and 18 to be small, the annular member 30 can be heated evenly with a heating time comparable to that of the eighth embodiment.

[0141] In the present embodiment, a core member made of a magnetic material is additionally provided. For example, the core member is provided inside the inner coil 17 (near the inner circumferential surface) and / or near the two axial end faces of the inner coil 17. In addition, the core member is provided outside the outer coil 18 (near the outer circumferential surface) and near the two axial end faces of the outer coil 18. By providing the core member, the heating efficiency can be improved.

[0142] In this embodiment, since the dimensional difference between the effective lengths of the induction coils 17 and 18 and the axial length of the annular member 30 is large, the allowable level for the shape change or position deviation of the annular member 30 is relaxed, and the versatility of the induction coils 17 and 18 is improved. It is possible to use one type of induction coils 17 and 18 to perform heat treatment on a plurality of annular members of various shapes. The replacement frequency of the inner coil 17 and the outer coil 18 is reduced. For example, it is particularly preferably applicable to the manufacture of annular members 30 in small batches with multiple varieties.

[0143] Through the above embodiment, as Figure 17 shown, it is possible to perform heat treatment on a plurality of annular members of various shapes. Heat treatment using induction coils with high versatility is beneficial for reducing manufacturing costs.

[0144] The annular member can be applied to, for example, Figure 18 bearings 900A, 900B, etc. that support the rotating shaft 963 of the electric motor 961 as shown.

[0145] In Figure 18 , the electric motor 961 is a brushless motor and has a cylindrical central housing 965 and a substantially disc-shaped front housing 967 that closes one open end of the central housing 965. Inside the central housing 965, the rotatable rotating shaft 963 is supported along its axis by bearings 900A, 900B disposed at the bottom of the front housing 967 and the central housing 965. A rotor 969 for driving the electric motor is provided around the rotating shaft 963, and a stator 971 is fixed to the inner peripheral surface of the central housing 965.

[0146] The electric motor 961 is usually mounted on a machine or a vehicle to rotationally drive the rotating shaft 963 supported by the bearings 900A and 900B.

[0147] The bearing element or the bearing can be applied to the rotational support part of a machine having a rotating part, various manufacturing devices such as a screw device such as a ball screw device and an actuator (a combination of a translation guide bearing and a ball screw, an XY table, etc.) and other translation devices. In addition, the bearing element or the bearing can be applied to a wiper, an electric window, an electric door, an electric seat, a steering column (for example, an electric tilt telescopic steering column), a universal joint, an intermediate gear, a rack and pinion pair, an electric power steering device, and a worm reducer and other steering devices. Moreover, the bearing element or the bearing can be applied to various vehicles such as an automobile, a motorcycle, and a train. As long as it is a relatively rotating part, the bearing of this configuration can be appropriately applied, which can improve product quality and reduce costs.

[0148] As a bearing having a ring-shaped member, various bearings such as rolling bearings and sliding bearings can be appropriately applied. For example, the bearing element can be applied to the outer ring and inner ring of a radial rolling bearing, the outer ring and inner ring of a radial cylindrical roller bearing using cylindrical rollers (including needle rollers), and the outer ring and inner ring of a radial tapered roller bearing using tapered rollers.

[0149] The above-described embodiments can be appropriately combined and implemented as long as there is no contradiction. In addition, the technical scope of the present invention is not limited to the scope described in the embodiments. Various changes or improvements can be made to the embodiments. The embodiments to which such changes or improvements are applied can also be included in the technical scope of the present invention. In addition, it is not limited to the described embodiments, and any combination of these configurations is also possible.

[0150] Description of Reference Numerals

[0151] 1 Radial rolling bearing

[0152] 2, 2a, 2b Outer ring

[0153] 3 Inner ring

[0154] 4 Rolling element

[0155] 5 Outer ring raceway

[0156] 6 Tapered surface

[0157] 7 Cylindrical surface

[0158] 8a, 8b Chamfered portion

[0159] 9 Cylindrical surface

[0160] 10a, 10b Chamfered portion

[0161] 11 Inner ring raceway

[0162] 12 Tapered surface

[0163] 13 Cylindrical surface

[0164] 14a, 14b Chamfered portion

[0165] 15 Cylindrical surface

[0166] 16a, 16b Chamfered portion

[0167] 17, 17a Inner coil

[0168] 18, 18a Outer coil

[0169] 19 Inner coil for reheating

[0170] 20 Outer coil for reheating

Claims

1. An induction heating method for an annular component, characterized in that, it includes a process of supplying current to an induction coil to perform induction heating on the annular component, the induction heating process includes the following treatment: performing induction heating on the annular component by using the induction coil arranged inside the radial direction of the annular component in a state where no substantial coil is arranged outside the radial direction of the annular component, or performing induction heating on the annular component by using the induction coil arranged outside the radial direction of the annular component in a state where no substantial coil is arranged inside the radial direction of the annular component, the effective length of the induction coil is set to be larger than the axial length of the annular component.

2. The induction heating method according to claim 1, characterized in that, the effective length of the induction coil is set to be 110% or more of the axial length of the annular component.

3. The induction heating method according to claim 1, characterized in that, the effective length of the induction coil is set to be 200% or more of the axial length of the annular component.

4. The induction heating method according to any one of claims 1 to 3, characterized in that, the induction heating process includes the following treatment: performing induction heating on the annular component by using an inner coil as the induction coil arranged inside the radial direction of the annular component in a state where no substantial coil is arranged outside the radial direction of the annular component; and performing induction heating on the annular component by using an outer coil as the induction coil arranged outside the radial direction of the annular component in a state where no substantial coil is arranged inside the radial direction of the annular component.

5. The induction heating method according to claim 4, characterized in that, it includes: a first heating process of supplying current to one of the inner coil and the outer coil to perform induction heating on the annular component so that at least a part of the annular component reaches a first target temperature; and a second heating process of, after the first heating process, supplying current to the other of the inner coil and the outer coil to perform induction heating on the annular component so that at least a part of the annular component reaches a second target temperature higher than the first target temperature.

6. The induction heating method according to claim 5, characterized in that, the one coil used in the first heating process is adjacently arranged to a first surface with a relatively large change in surface height among the inner surface and the outer surface of the annular component, the other coil used in the second heating process is adjacently arranged to a second surface with a relatively consistent surface height among the inner surface and the outer surface of the annular component.

7. The induction heating method according to any one of claims 1 to 6, characterized in that, after the induction heating process, there is also a process of reheating the annular component.

8. An induction heating method, characterized in that, it includes: a process of preparing a first coil arranged inside the radial direction of an annular component and a second coil arranged outside the radial direction of the annular component; The first heating step: supplying current to one of the first coil and the second outer coil to inductively heat the ring-shaped component so that at least a part of the ring-shaped component reaches a first target temperature; and The second heating step: after the first heating step, supplying current to the other one of the first coil and the second coil to inductively heat the ring-shaped component so that at least a part of the ring-shaped component reaches a second target temperature higher than the first target temperature.

9. The induction heating method according to claim 8, wherein the one coil used in the first heating step is adjacently arranged adjacent to a first surface with a relatively large change in surface height among the inner surface and the outer surface of the ring-shaped component, the other coil used in the second heating step is adjacently arranged adjacent to a second surface with relatively consistent surface height among the inner surface and the outer surface of the ring-shaped component.

10. The induction heating method according to claim 8 or 9, wherein at least one of the first heating step and the second heating step is implemented in a state where both the first coil and the second coil are adjacently arranged to the ring-shaped component.

11. The induction heating method according to claim 8 or 9, wherein at least one of the first heating step and the second heating step is implemented in a state where only one of the first coil and the second coil is adjacently arranged to the ring-shaped component.

12. A manufacturing method of a ring-shaped component, wherein it includes a step of heat-treating the ring-shaped component by using the induction heating method according to any one of claims 1 to 11.

13. A ring-shaped component, wherein it is manufactured by using the manufacturing method according to claim 12.

14. A manufacturing method of a bearing, wherein it includes a step of heat-treating the ring-shaped component of the bearing by using the induction heating method according to any one of claims 1 to 11.

15. A bearing, wherein it is manufactured by using the manufacturing method according to claim 14.

16. A manufacturing method of a vehicle, wherein it is a manufacturing method of a vehicle having a ring-shaped component, including a step of heat-treating the ring-shaped component by using the induction heating method according to any one of claims 1 to 11.

17. A manufacturing method of a mechanical device, wherein it is a manufacturing method of a mechanical device having a ring-shaped component, including a step of heat-treating the ring-shaped component by using the induction heating method according to any one of claims 1 to 11.

18. An induction heating device, wherein for inductively heating a ring-shaped component, it includes: an induction coil; and a power supply device for supplying current to the induction coil, in a state where no substantial coil is arranged radially outside the ring-shaped component, the induction coil is arranged radially inside the ring-shaped component, or in a state where no substantial coil is arranged radially inside the ring-shaped component, the induction coil is arranged radially outside the ring-shaped component, The effective length of the induction coil is set to be the same as or greater than the axial length of the annular member.

19. An induction heating device, characterized in that it inductively heats an annular member, comprising: a first coil disposed radially inside the annular member; a second coil disposed radially outside the annular member; and a power supply device that supplies current to the first coil and the second coil, wherein the power supply device includes: a first mode that supplies current to one of the first coil and the second coil to inductively heat the annular member so that at least a part of the annular member reaches a first target temperature; and a second mode that supplies current to the other of the first coil and the second coil to inductively heat the annular member so that at least a part of the annular member reaches a second target temperature higher than the first target temperature.

Images