Reduction gear and heat treatment method

Abstract

To provide a technology that can achieve reduction of manufacturing costs.SOLUTION: A speed reducer of the disclosure is an eccentric oscillation type speed reducer including a crank shaft which is a rotating body. The rotating body includes a seal part with which an oil seal contacts. A high hardness area is provided at the seal part by laser hardening. A low hardness area having hardness lower than that of the high hardness area is provided at an outer surface part of the rotating body.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a reduction gear device and a heat treatment method. [Background technology]

[0002] Patent Document 1 discloses a reduction gear transmission having a crankshaft, which is a rotating body, and this rotating body has a seal portion with which an oil seal comes into contact. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-124730 Summary of the Invention [Problem to be solved by the invention]

[0004] The seal portion of the rotating body requires high hardness due to the influence of the oil seal. This is not limited to the crankshaft used in the eccentric oscillating reduction gear, but is also common to the vibrator used as the rotating body in the flexure mesh reduction gear. No technology has yet been proposed that can increase the hardness of the seal portion of the rotating body while reducing manufacturing costs.

[0005] One of the objects of the present disclosure is to provide a technique that can reduce manufacturing costs. [Means for solving the problem]

[0006] The reduction gear device disclosed herein is an eccentric oscillating type reduction gear device that includes a crankshaft as a rotating body, the rotating body including a seal portion with which an oil seal comes into contact, the seal portion being provided with a high hardness region by laser hardening, and the outer surface portion of the rotating body being provided with a low hardness region that is lower in hardness than the high hardness region.

[0007] Another reduction gear device disclosed herein is a flexible meshing type reduction gear device having a vibrator shaft that is a rotating body, the rotating body having a seal portion with which an oil seal comes into contact, the seal portion having a high hardness region formed by laser hardening, and the outer surface portion of the rotating body having a low hardness region that is lower in hardness than the high hardness region.

[0008] Another reduction gear disclosed herein is an eccentric oscillating type reduction gear having a crankshaft which is a rotating body, wherein the rotating body has an eccentric portion which oscillates an oscillating gear, a rolling portion in which a rolling body arranged between the oscillating gear and the eccentric portion rolls, and a sealing portion with which an oil seal comes into contact, wherein high hardness regions are provided in the rolling portion and the sealing portion, and a low hardness region which is lower in hardness than the high hardness region is provided on the outer surface of the rotating body between the rolling portion and the sealing portion.

[0009] Another reduction gear device disclosed herein is a flexible meshing type reduction gear device having an exciter shaft which is a rotating body, the rotating body having an exciter that flexibly deforms a flexible gear, a rolling section in which a rolling body arranged between the flexible gear and the exciter rolls, and a sealing section in which an oil seal comes into contact, the rolling section and the sealing section having high hardness regions, and a low hardness region having a lower hardness than the high hardness region provided on the outer surface of the rotating body between the rolling section and the sealing section.

[0010] Another reduction gear device disclosed herein is an eccentric oscillating type reduction gear device having a crankshaft which is a rotating body, wherein the rotating body has an eccentric portion which oscillates an oscillating gear, a rolling portion in which a rolling body arranged between the oscillating gear and the eccentric portion rolls, and a sealing portion with which an oil seal comes into contact, wherein each of the rolling portion and the sealing portion is provided with a high hardness region and a linear low hardness region which is lower in hardness than the high hardness region, the low hardness region of the rolling portion is provided within a low load range within the entire circumferential range of the rolling portion where the load on the rolling portion is low, and the circumferential position of the low hardness region of the sealing portion is aligned with the circumferential position of the low hardness region of the rolling portion.

[0011] Another reduction gear device disclosed herein is a flexible meshing type reduction gear device that includes an exciter shaft that is a rotating body, wherein the rotating body includes an exciter that flexibly deforms a flexible gear, a rolling portion in which a rolling body that is arranged between the flexible gear and the exciter rolls, and a sealing portion in which an oil seal comes into contact, wherein each of the rolling portion and the sealing portion is provided with a high hardness region and a low hardness region that is lower in hardness than the high hardness region, and the low hardness region of the rolling portion is provided within a low load range within the entire circumferential range of the rolling portion where the load on the rolling portion is low, and the circumferential position of the low hardness region of the sealing portion is aligned with the circumferential position of the low hardness region of the rolling portion.

[0012] The heat treatment method disclosed herein is a heat treatment method for a rotating body that is the crankshaft of an eccentric oscillating speed reducer, wherein the rotating body comprises an eccentric portion that oscillates an oscillating gear, a rolling portion in which a rolling element located between the oscillating gear and the oscillating portion rolls, and a sealing portion in which an oil seal is located, and the heat treatment method includes a first step of hardening the rolling portion over its entire circumferential range by changing the irradiation position of the laser light in the circumferential direction, and then re-irradiating the laser light to a portion of the range that has already been irradiated with the laser light, and a second step of hardening the sealing portion over its entire circumferential range by changing the irradiation position of the laser light in the circumferential direction, and then re-irradiating the laser light to a portion of the range that has already been irradiated with the laser light, wherein the re-irradiation point of the laser light in the first step is linear and is set to fall within a low-load portion of the entire circumferential range of the rolling portion that has a low load on the rolling portion, and the circumferential position of the re-irradiation point of the laser light in the rolling portion is aligned with the circumferential position of the re-irradiation point of the laser light in the sealing portion.

[0013] The heat treatment method disclosed herein is a heat treatment method for a rotating body that is a vibrator shaft of a flexible mesh reduction gear, the rotating body comprising a vibrator that flexibly deforms a flexible gear, a rolling portion in which rolling elements disposed between the flexible gear and the vibrator roll, and a sealing portion in contact with an oil seal, the heat treatment method comprising a first step of quenching the rolling portion over the entire circumferential range by changing the irradiation position of a laser beam in the circumferential direction, and then re-irradiating a part of the range that has already been irradiated with the laser beam with the laser beam; and a second process of re-irradiating the laser light to a portion of the area already irradiated with the laser light by changing the position in the circumferential direction to harden the entire circumferential range of the sealing portion, wherein the re-irradiation area of ​​the laser light in the first process is linear and is set to fall within a low-load area of ​​the entire circumferential range of the rolling portion where the load on the rolling portion is low, and the circumferential position of the re-irradiation area of ​​the laser light in the rolling portion and the circumferential position of the re-irradiation area of ​​the laser light in the sealing portion are aligned. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to reduce manufacturing costs. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a side cross-sectional view of a reduction gear transmission according to a first embodiment. [Figure 2] FIG. 2 is a side cross-sectional view showing the crankshaft of the first embodiment together with the surrounding structure. [Figure 3] 3(a) is a cross-sectional view taken along line AA in FIG. 2, FIG. 3(b) is a cross-sectional view taken along line BB in FIG. 2, FIG. 3(c) is a cross-sectional view taken along line CC in FIG. 2, and FIG. 3(d) is a cross-sectional view taken along line DD in FIG. 2. [Figure 4] 1 is a graph showing the relationship between the depth of a high hardness region and Vickers hardness. [Figure 5] FIG. 10 is a process diagram showing a manufacturing process for obtaining a rotating body of a reference embodiment. [Figure 6] FIG. 2 is a process diagram showing a manufacturing process for obtaining the rotating body of the first embodiment. [Figure 7] Figure 7(a) is a schematic diagram showing the state during the first step of the first embodiment, Figure 7(b) is a schematic diagram showing the state where laser light is being re-irradiated in the first step, Figure 7(c) is a schematic diagram showing the state during the second step, and Figure 7(d) is a schematic diagram showing the state where laser light is being re-irradiated in the second step. [Figure 8] FIG. 6 is a side cross-sectional view of a reduction gear transmission according to a second embodiment. [Figure 9] FIG. 10 is a side cross-sectional view showing the vibrator shaft of the second embodiment together with the surrounding structure. [Figure 10] 10(a) is a cross-sectional view taken along line EE in FIG. 9, FIG. 10(b) is a cross-sectional view taken along line FF in FIG. 9, and FIG. 10(c) is a cross-sectional view taken along line GG in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] The following describes the embodiments. Identical components are designated by the same reference numerals, and redundant explanations will be omitted. In each drawing, components are omitted, enlarged, or reduced as appropriate for the sake of convenience. The drawings should be viewed in accordance with the orientation of the reference numerals.

[0017] (First embodiment) Referring to Figure 1, the reduction gear 10 is an eccentric oscillating type reduction gear including a crankshaft 14 as a rotating body 12. The reduction gear 10 also includes an oscillating gear 16 that is oscillated by the crankshaft 14, and a gear bearing 18 arranged between the crankshaft 14 and the oscillating gear 16. The reduction gear 10 also includes an external gear 20 and an internal gear 22 that mesh with each other, one of which constitutes the oscillating gear 16, a casing 24 arranged on the outer periphery of the oscillating gear 16, and carriers 26A, 26B provided axially to the external gear 20. The reduction gear 10 also includes oil seals 28A, 28B arranged between the carriers 26A, 26B and the crankshaft 14, and input bearings 30A, 30B arranged between the carriers 26A, 26B and the crankshaft 14. The reduction gear 10 of this embodiment is an externally oscillating type in which the external gear 20 is an oscillating gear 16. Hereinafter, the direction along the rotation center line CL1 of the rotating body 12 will be referred to as the axial direction X. For convenience, one side of the axial direction X (the right side in FIG. 1) will be referred to as the input side, and the other side (the left side in FIG. 1) will be referred to as the anti-input side.

[0018] The crankshaft 14 can be rotated by rotational power transmitted from a drive device (not shown). The drive device is, for example, a motor, a gear motor, an engine, etc. The reduction gear transmission 10 of this embodiment is a center crank type in which the crankshaft 14 is provided coaxially with the center axis CL2 of the internal gear 22.

[0019] The crankshaft 14 includes a shaft portion 32 to which rotational power is transmitted from a drive device, and a plurality of eccentric portions 34A, 34B that are rotatable integrally with the shaft portion 32. The eccentric portions 34A, 34B are provided as part of the same member as the shaft portion 32.

[0020] The outer peripheral surfaces of the eccentric portions 34A, 34B are circular. The axis CL3 of the eccentric portions 34A, 34B is eccentric with respect to the rotation center line CL1 of the crankshaft 14 by an eccentricity amount e. The eccentric portions 34A, 34B can oscillate the oscillating gear 16 by rotating about the rotation center line CL1 of the crankshaft 14. The multiple eccentric portions 34A, 34B include a first eccentric portion 34A and a second eccentric portion 34B. The phases of the maximum eccentric directions (described below) of adjacent eccentric portions 34A, 34B are shifted by, for example, 360° / (the number of eccentric portions 34A, 34B) (180° in this embodiment). The number of eccentric portions 34A, 34B is not particularly limited and may be one or three or more.

[0021] The oscillating gears 16 are individually provided corresponding to the plurality of eccentric portions 34A, 34B of the crankshaft 14, and are supported by the corresponding eccentric portions 34A, 34B via gear bearings 18.

[0022] The gear bearings 18 are individually provided corresponding to the multiple oscillating gears 16 and the multiple eccentric portions 34A, 34B, respectively, and are arranged between the corresponding oscillating gears 16 and eccentric portions 34A, 34B. The gear bearings 18 include multiple rolling elements 36 arranged between the oscillating gear 16 and the eccentric portions 34A, 34B of the crankshaft 14, and a retainer 38 that maintains the relative positions of the multiple rolling elements 36. In this embodiment, the rolling elements 36 are rollers. The gear bearings 18 do not include a dedicated inner ring. Instead, the eccentric portions 34A, 34B double as inner rings, and the crankshaft 14 includes rolling portions 40A, 40B on which the rolling elements 36 roll. The rolling portions 40A, 40B are formed by the outer peripheries of the eccentric portions 34A, 34B. The rolling portions 40A, 40B include a first rolling portion 40A formed by the outer periphery of the first eccentric portion 34A and a second rolling portion 40B formed by the outer periphery of the second eccentric portion 34B. The gear bearing 18 does not have a dedicated outer ring. Instead, the inner circumferential surface of the through hole of the oscillating gear 16 doubles as the outer ring.

[0023] The internal gear 22 is integrated with a casing 24. The casing 24 houses other components of the reduction gear 10, such as the oscillating gear 16.

[0024] The carriers 26A, 26B include an input side carrier 26A arranged on the input side of the external gear 20 and a counter-input side carrier 26B arranged on the counter-input side of the external gear 20. The carriers 26A, 26B are integrated with an inner pin 42 that passes through the external gear 20.

[0025] The oil seals 28A, 28B include an input-side oil seal 28A arranged on the input side of the gear bearing 18, and a counter-input-side oil seal 28B arranged on the counter-input side of the gear bearing 18. The input-side oil seal 28A is arranged between the input-side carrier 26A and the rotating body 12. The counter-input-side oil seal 28B is arranged between the counter-input-side carrier 26B and the rotating body 12.

[0026] The oil seals 28A, 28B seal an enclosed space 44 in which the external gear 20 and the internal gear 22 are disposed. A lubricant (not shown) used to lubricate the external gear 20 and the internal gear 22 is enclosed in the enclosed space 44. The oil seals 28A, 28B include a fitting portion 46 that is attached by interference fit to one of the carriers 26A, 26B and the rotating body 12, and a lip portion 48 that slides on the other of the carriers 26A, 26B and the rotating body 12. In this embodiment, the fitting portion 46 is attached to the carriers 26A, 26B, and the lip portion 48 slides on the rotating body 12.

[0027] The input bearings 30A, 30B include an input side input bearing 30A arranged on the input side of the gear bearing 18, and a counter input side input bearing 30B arranged on the counter input side of the gear bearing 18. The input side input bearing 30A is arranged between the input side carrier 26A and the rotating body 12. The counter input side input bearing 30B is arranged between the counter input side carrier 26B and the rotating body 12. The input bearings 30A, 30B are rolling bearings such as ball bearings. The input bearings 30A, 30B are equipped with dedicated outer and inner rings in addition to a plurality of rolling elements.

[0028] A member that outputs rotational power to a driven device is called an output member, and a member that is fixed to an external member to support the reduction gear transmission 10 is called a fixed member. The output member rotates in synchronization with the rotation component of one of the external gear 20 and the internal gear 22, thereby outputting that rotation component to the driven device. One of the output member and the fixed member is the carriers 26A, 26B, and the other is the casing 24. When the carriers 26A, 26B serve as the output member, the external gear 20 rotates, and when the casing 24 serves as the output member, the internal gear 22 rotates.

[0029] The operation of the reduction gear 10 described above will now be described. When rotational power is transmitted from the drive device to the crankshaft 14, the crankshaft 14 rotates about the rotation center line CL1, and the eccentric portions 34A, 34B of the crankshaft 14 cause the oscillating gear 16 to oscillate. When the oscillating gear 16 oscillates, the meshing positions of the external gear 20 and the internal gear 22 sequentially shift in the circumferential direction. As a result, one of the external gear 20 and the internal gear 22 rotates together with the output member. The rotation of the crankshaft 14 is reduced at a reduction ratio corresponding to the external gear 20 and the internal gear 22, and is then output to the driven device via the output member.

[0030] 2, the rotating body 12, which is the crankshaft 14, includes, in addition to the rolling portions 40A and 40B described above, seal portions 60A and 60B with which the oil seals 28A and 28B come into contact, and bearing arrangement portions 62A and 62B in which the input bearings 30A and 30B are arranged. These are provided on the outer periphery of the rotating body 12.

[0031] The seal portions 60A, 60B include an input-side seal portion 60A with which the input-side oil seal 28A comes into contact, and a counter-input-side seal portion 60B with which the counter-input-side oil seal 28B comes into contact. When the lip portions 48 of the oil seals 28A, 28B slide against the rotating body 12, the contact points (sliding points) of the lip portions 48 become the seal portions 60A, 60B. On the other hand, when the fitting portions 46 of the oil seals 28A, 28B are attached to the crankshaft 14, the contact points of the fitting portions 46 become the seal portions 60A, 60B.

[0032] The bearing arrangement portions 62A, 62B include an input-side bearing arrangement portion 62A in which the input-side input bearing 30A is arranged, and a counter-input-side bearing arrangement portion 62B in which the counter-input-side input bearing 30B is arranged. The bearing arrangement portions 62A, 62B are provided in an outer circumferential intermediate portion 64 provided between the rolling portions 40A, 40B and the sealing portions 60A, 60B.

[0033] The difference in radius between the seal portions 60A, 60B located axially outward of the bearing arrangement portions 62A, 62B and the bearing arrangement portions 62A, 62B is 2 mm or less. This means that the difference in radius between the input side seal portion 60A and the input side bearing arrangement portion 62A is 2 mm or less, and the difference in radius between the non-input side seal portion 60B and the non-input side bearing arrangement portion 62B is 2 mm or less. In this embodiment, these radius differences are 0. Here, "radius difference" refers to the difference in radius between the outer diameters of the two locations being mentioned.

[0034] The rotating body 12 also has a hollow portion 66 that opens to the axial end of the rotating body 12, a bolt hole 68 provided at the axial end of the rotating body 12, and a chucked portion 70 for chucking by a chuck device.

[0035] The hollow portion 66 of this embodiment penetrates the crankshaft 14 in the axial direction X. A bolt (not shown) for connecting to a mating device such as a drive device is screwed into the bolt hole 68. The bolt hole 68 opens to the axial end surface of the crankshaft 14. The bolt hole 68 is arranged on the input side of the input side seal portion 60A at a position where it does not radially overlap with the input side seal portion 60A. The chucked portion 70 is provided on the outer periphery of the rotor 12, axially outward of the input side seal portion 60A.

[0036] 2 and 3(a) to 3(d), in these figures, a high hardness region 72, which will be described later, is shown with double hatching, a first low hardness region 74 is shown with single hatching, and a second low hardness region 76 is shown without hatching.

[0037] A high-hardness region 72 is provided on the outer surface of the rotating body 12. The high-hardness region 72 is provided in the seal portions 60A, 60B and the rolling portions 40A, 40B, which form the outer surface of the rotating body 12. The high-hardness region 72 is provided in a circumferentially continuous range in each of the seal portions 60A, 60B and the rolling portions 40A, 40B of the rotating body 12. The high-hardness region 72 in the rolling portions 40A, 40B is provided to improve the fatigue strength of the rolling elements 36 against rolling fatigue. The high-hardness region 72 in the seal portions 60A, 60B is provided to prevent wear due to sliding when the lip portions 48 of the oil seals 28A, 28B slide against the seal portions 60A, 60B, as in this embodiment. In contrast, the high hardness regions 72 of the seal portions 60A, 60B are provided to enable the mating portions 46 of the oil seals 28A, 28B to resist the elastic restoring force of the oil seals 28A, 28B when they are attached to the seal portions 60A, 60B.

[0038] The outer surface of the rotor 12 is provided with low hardness regions 74, 76 that are lower in hardness than the high hardness region 72. The hardness of the outer surface here refers to the Vickers hardness measured by a method conforming to JIS Z2244. This hardness refers to the average value of all hardness measured at predetermined unit depths (e.g., 0.1 mm) over a predetermined range (e.g., 1.0 mm) in the depth direction (normal direction) from the outer surface of the referenced location. The difference in hardness between the high hardness region 72 and the low hardness regions 74, 76 of the outer surface is, for example, 50 HV or more in Vickers hardness.

[0039] The low hardness regions 74, 76 include a first low hardness region 74 provided in the seal portions 60A, 60B and the rolling portions 40A, 40B, and a second low hardness region 76 provided in a location different from the seal portions 60A, 60B and the rolling portions 40A, 40B.

[0040] The first low hardness regions 74 of the seal portions 60A, 60B are partially provided in the seal portions 60A, 60B at locations other than the high hardness regions 72. The seal portions 60A, 60B are thus provided with the high hardness regions 72 and the first low hardness regions 74.

[0041] The first low hardness regions 74 of the rolling parts 40A, 40B are partially provided in the rolling parts 40A, 40B at locations other than the high hardness regions 72. The high hardness regions 72 and the first low hardness regions 74 are provided in the rolling parts 40A, 40B.

[0042] The second low-hardness regions 76 are provided, for example, in the outer circumferential intermediate portion 64, axial end portion, hollow portion 66, and chucked portion 70 of the rotating body 12. The second low-hardness regions 76 in the outer circumferential intermediate portion 64 are provided in a continuous range over the entire circumference of the outer circumferential intermediate portion 64. In other words, the second low-hardness regions 76 are provided in a continuous range over the entire circumference of the bearing arrangement portions 62A, 62B of the outer circumferential intermediate portion 64. The same applies to the second low-hardness regions 76 provided in the axial end portion, hollow portion 66, and chucked portion 70. The bolt holes 68 are provided in the second low-hardness regions 76 that are continuous in the depth direction from the axial end portion of the rotating body 12.

[0043] The first low hardness region 74 has a lower hardness than the high hardness region 72 and a higher hardness than the second low hardness region 76. The first low hardness region 74 has a linear shape extending in the axial direction X of the rotor 12.

[0044] The high hardness region 72 and the first low hardness region 74 are formed by a surface treatment region 78 provided on the workpiece by performing a surface treatment on the workpiece. In this embodiment, laser heating is used as this surface treatment. The high hardness region 72 and the first low hardness region 74 can be considered to be regions that are harder than the base material region due to the surface heat treatment of the workpiece. The high hardness region 72 is provided by partial hardening through this laser heating, i.e., laser hardening. Therefore, the microstructure of the high hardness region 72 has a hardened structure such as α-martensite as the main phase. The first low hardness region 74 is provided by partial tempering through laser heating. Therefore, the microstructure of the first low hardness region 74 has a tempered structure such as trussite or sorbite as the main phase. The first low hardness region 74 is a region known as a soft zone, and is provided at the location where the laser beam is re-irradiated, as described below.

[0045] In contrast, the second low-hardness region 76 is constituted by a base material region 80 having the hardness of the base material of the workpiece to be surface treated. The microstructure of the second low-hardness region 76 has a standard structure, such as a two-phase structure of ferrite and pearlite, as the main phase.

[0046] FIG. 4 shows the relationship between the depth from the surface of the high hardness region 72 and the Vickers hardness. In FIG. 4, the Vickers hardness measured at multiple points in the depth direction from the surface of the high hardness region 72 is plotted. The depth direction here refers to the direction perpendicular to the surface of the high hardness region 72. The numbers attached to the measurement points in the graph indicate the amount of change in Vickers hardness from the adjacent measurement point on the surface side (hereinafter referred to as the amount of hardness change). This amount of hardness change indicates the amount of change in Vickers hardness per 0.1 mm in the depth direction Pa.

[0047] The high hardness region 72 formed by laser hardening is composed of a surface region 82 and a hardness transition region 84. The surface region 82 continues from the surface of the high hardness region 72, and the hardness transition region 84 continues from the surface region 82 to the base material region 80 (second low hardness region 76). The hardness transition region 84 is a region where hardness rapidly decreases in the depth direction. The hardness transition region 84 begins where the amount of hardness change in the depth direction switches from a value greater than or equal to 0 to a negative value, and includes a region where the amount of hardness change is at least -60 or less. The length of the hardness transition region 84 in the depth direction is, for example, 0.3 mm to 0.8 mm. The amount of hardness change refers to the amount of change in Vickers hardness per 0.1 mm in the depth direction.

[0048] The surface layer region 82 is a region where the hardness does not decrease as rapidly as in the hardness transition region 84. The surface layer region 82 is defined as including a location where the amount of change in hardness is equal to or greater than 0. Even when the amount of change in hardness is a negative value, the surface layer region 82 is a region where the amount of change in hardness is at least greater than -60. The surface layer region 82 is also a region where there is no significant increase or decrease in Vickers hardness. Due to this relationship, in the surface layer region 82, for example, the difference between the maximum and minimum values ​​of Vickers hardness is equal to or less than 100, and the amount of change in hardness is in the range of greater than -60 and equal to or less than +60.

[0049] The base material region 80 begins at the point where the amount of change in hardness in the depth direction from the hardness transition region 84 switches from a negative value to a value greater than or equal to 0. In the base material region 80, the hardness does not increase or decrease significantly in the depth direction. Due to this relationship, in the base material region 80, for example, the difference between the maximum and minimum Vickers hardness values ​​is 50 or less, and the amount of change in hardness is between -50 and +50.

[0050] See Figures 3(b) and 3(c). The direction from the rotational center line CL1 of the crankshaft 14 toward the axis CL3 of the eccentric portions 34A, 34B is called the maximum eccentric direction Pa1, and the direction extending from the rotational center line CL1 in the opposite direction to the maximum eccentric direction Pa1 is called the anti-maximum eccentric direction Pa2. The axis CL2 of the eccentric portions 34A, 34B refers to the geometric center (center of gravity) of the shape formed by the outer circumferential surfaces of the eccentric portions 34A, 34B in a cross section perpendicular to the axial direction X. The line extending from the axis CL2 of the eccentric portions 34A, 34B in the maximum eccentric direction Pa1 is called the first reference line La1, and the line extending from the axis CL2 in the anti-maximum eccentric direction Pa2 is called the second reference line La2.

[0051] In the rolling portions 40A and 40B of the eccentric portions 34A and 34B, the circumferential range of ±90 degrees from the first reference line La1 is called the high load range Sa1, and the circumferential range of ±90 degrees from the second reference line La2 is called the low load range Sa2. The maximum load is applied to the rolling portions 40A and 40B in the high load range Sa1, and almost no load is applied in the low load range Sa2. The low load range Sa2 can be considered to be a range in which the load on the rolling portions 40A and 40B is low within the entire circumferential range of the rolling portions 40A and 40B. In the low load range Sa2, no load is applied in particular to a range Sa3 of ±30 degrees from the second reference line La2.

[0052] The first low hardness regions 74 of the rolling parts 40A, 40B are provided within the low load range Sa2. This means that the entire first low hardness regions 74 of the rolling parts 40A, 40B are provided so as to fall within the low load range Sa2. The first low hardness regions 74 are provided within a range Sa3 in the low load range Sa2. The first high hardness regions 72 are provided throughout the high load range Sa1 and in locations other than the first low hardness regions 74 in the low load range Sa2. The first low hardness regions 74 of each of the multiple rolling parts 40A, 40B are provided in the low load range Sa2 corresponding to the individual rolling part 40A, 40B.

[0053] The circumferential positions of the first low-hardness regions 74 of the seal portions 60A and 60B are aligned with the circumferential positions of the first low-hardness regions 74 of the rolling portions 40A and 40B. This is referred to as position condition A. In an eccentric oscillating reduction gear device, the circumferential positions of the seal portions 60A and 60B refer to the circumferential positions of a circle centered on the rotation center line CL1 of the rotating body 12. Furthermore, the circumferential positions of the rolling portions 40A and 40B refer to the circumferential positions of a circle centered on the axis CL2 of the eccentric portions 34A and 34B on which the rolling portions 40A and 40B are provided. This means that the circumferential range in which the first low-hardness regions 74 of the seal portions 60A and 60B exist as viewed from the rotation center line CL1 of the rotating body 12 is aligned with the circumferential range in which the first low-hardness regions 74 of the rolling portions 40A and 40B exist as viewed from the axis CL2 of the eccentric portions 34A and 34B. Here, "aligned" includes cases where the circumferential positions of the first low hardness regions 74 are the same in the seal portions 60A, 60B and the rolling portions 40A, 40B, as well as cases where they are approximately the same. In other words, "aligned" includes not only cases where the circumferential positions (phases) of the regions 74 are completely aligned, but also cases where parts of the regions 74 are aligned.

[0054] When there are multiple eccentric portions 34A, 34B, position condition A only needs to be satisfied between the rolling portion 40A, 40B of any of the eccentric portions 34A, 34B and the seal portion 60A, 60B. In this embodiment, position condition A is satisfied between the first rolling portion 40A of the first eccentric portion 34A and the input side seal portion 60A, and between the second rolling portion 40B of the second eccentric portion 34B and the non-input side seal portion 60B. Specifically, the circumferential position of the first low hardness region 74 of the first rolling portion 40A is the same as the circumferential position of the first low hardness region 74 of the input side seal portion 60A, and the circumferential position of the first low hardness region 74 of the second rolling portion 40B is the same as the circumferential position of the first low hardness region 74 of the non-input side seal portion 60B. Alternatively, the position condition A may be satisfied between one of the plurality of eccentric portions 34A, 34B and both of the plurality of seal portions 60A, 60B.

[0055] The manufacturing process for obtaining the above-described rotating body 12 will now be described. See FIG. 5. First, the manufacturing process of the reference embodiment will be described. In this manufacturing process, a rough machining step S10 is performed in which the material of the rotating body 12 is machined by cutting or other machining to form the outer shape of the rotating body 12. This is followed by a heat treatment step S12 in which the entire rotating body 12 is quenched by carburizing or other quenching to perform a surface heat treatment. After the heat treatment step S12, a finish machining step S14 is performed in which the surface of the quenched portions of the rotating body 12 is ground to remove thermal distortion. After the heat treatment step S12, a hole machining step S16 is performed in which bolt holes 68 are formed in the rotating body 12.

[0056] Here, the heat treatment step S12 is performed mainly to ensure the hardness of the portions requiring high hardness (seal portions 60A, 60B, rolling portions 40A, 40B). If the entire rotor 12 is quenched in this heat treatment step S12, the hardness of portions other than those requiring high hardness will also increase. For this reason, in the finishing machining step S14 and the hole machining step S16, machining of high-hardness portions is required for portions that do not originally require high hardness (bearing arrangement portions 62A, 62B, axial end portions, hollow portion 66, etc.).

[0057] A manufacturing process of this embodiment that addresses this issue will now be described. See FIG. 6 . In this manufacturing process, a rough machining step S20 is performed to form the outer shape of the rotor 12, as in the reference embodiment. After the rough machining step S20, a pre-machining step is performed before the heat treatment step S26. This pre-machining step includes a finish machining step S22 in which the outer surface of the rotor 12 is ground, targeting areas other than the areas to be heat treated. Examples of areas other than the areas to be heat treated include the outer peripheral intermediate portion 64, hollow portion 66, and chucked portion 70 of the rotor 12. This pre-machining step also includes the hole machining step S24 described above in which bolt holes 68 are formed at the axial ends of the rotor 12.

[0058] Thereafter, a heat treatment step S26 is performed to partially quench a portion of the rotor 12, targeting the portion to be heat treated. As mentioned above, the portion to be heat treated here refers to the seal portions 60A, 60B and rolling portions 40A, 40B of the rotor 12. This will be described in detail later.

[0059] After the heat treatment step S26, a finish processing step S28 is performed to grind the surface of the rotor 12, targeting the heat-treated areas in the heat treatment step S26 (the seal portions 60A, 60B and the rolling portions 40A, 40B of the rotor 12). The finish processing steps S22 and S28 described so far are performed by grinding the surface of the rotor 12 to achieve the target surface roughness.

[0060] The heat treatment method used in the heat treatment step S26 will now be described with reference to Figures 7(a) to (d). This heat treatment method is performed by performing surface heat treatment using a laser beam 92 using a heat treatment device 90. The heat treatment device 90 includes a head 94 that irradiates the laser beam 92 onto the rotating body 12, and a chuck device (not shown) that can move the rotating body 12 while chucking the rotating body 12.

[0061] The heat treatment method includes a first step of heat treating the rolling portions 40A, 40B and a second step of heat treating the seal portions 60A, 60B. The order of the first step and the second step is not particularly important. Furthermore, the order of the first step for each of the multiple rolling portions 40A, 40B and the second step for each of the multiple seal portions 60A, 60B is also not particularly important. For example, the order may be the first step for the first rolling portion 40A, then the second step for the input-side seal portion 60A, then the first step for the second rolling portion 40B, then the second step for the non-input-side seal portion 60B.

[0062] In both the first and second steps, first, the chucked portion 70 (see FIG. 2) of the rotating body 12 is chucked by a chucking device. At this time, the rotating body 12 is chucked by applying a radially inward pressing force to the chucked portion 70 of the rotating body 12. The first and second steps are performed while maintaining the same chucking state.

[0063] In both the first and second steps, the rotating body 12 is heat-treated by irradiating the rotating body 12 with a laser beam 92 from the head 94. At this time, the irradiation position of the laser beam 92 is changed in the circumferential direction to heat-treat the rotating body 12. To achieve this, the rotating body 12 may be rotated by a chuck device, or the head 94 may be rotated around the rotating body 12. In the first step, either the rotating body 12 or the head 94 is moved so as to rotate around the axis CL2 of the eccentric portions 34A, 34B on which the rolling portions 40A, 40B are provided (see FIG. 7(a)). In the second step, either the rotating body 12 or the head 94 is moved so as to rotate around the rotation center line CL1 of the rotating body 12 (see FIG. 7(c)). This allows the laser beam to be irradiated while maintaining a constant distance from the irradiation position of the laser beam 92 to the head 94.

[0064] In the first step, the irradiation position of the laser beam 92 is changed in the circumferential direction to harden the rolling portions 40A, 40B over the entire circumferential range of the eccentric portions 34A, 34B, and then the laser beam is re-irradiated to a portion of the range that has already been irradiated with the laser beam 92. The above series of operations is performed in one process. The irradiation position of the laser beam 92 on the rotating body 12 is moved relatively in the circumferential direction of the eccentric portions 34A, 34B (the circumferential direction of a circle centered on the axis CL2 of the eccentric portions 34A, 34B), thereby performing heat treatment in one process. The area to be re-irradiated with the laser beam at this time is set to be linear and fall within the aforementioned low load range Sa2 of the rolling portions 40A, 40B.

[0065] In the second step, the laser beam irradiation position is changed in the circumferential direction to harden the seal portions 60A, 60B over the entire circumferential range of the rotating body 12, and then the laser beam is re-irradiated to a part of the range that has already been irradiated with the laser beam. At this time, the re-irradiation area of ​​the laser beam is set to form a line.

[0066] In both the first and second steps, the areas re-irradiated with the laser beam are tempered to form first low-hardness regions 74. In contrast, areas other than the areas re-irradiated with the laser beam are laser hardened to form high-hardness regions 72.

[0067] The circumferential positions of the laser beam re-irradiation points of the rolling portions 40A, 40B in the first step and the circumferential positions of the laser beam re-irradiation points of the sealing portions 60A, 60B in the second step are aligned. This is referred to as positional condition B. The definitions of the circumferential positions of the rolling portions 40A, 40B and the sealing portions 60A, 60B are the same as those described above. The definition of "aligned" is also the same as that described above. This allows the aforementioned positional condition A to be satisfied between the first low-hardness regions 74 of the rolling portions 40A, 40B and the first low-hardness regions 74 of the sealing portions 60A, 60B. Similar to positional condition A, when there are multiple eccentric portions 34A, 34B, positional condition B only needs to be satisfied between the rolling portions 40A, 40B of any of the eccentric portions 34A, 34B and the sealing portions 60A, 60B. In this embodiment, position condition B is satisfied between the first rolling portion 40A of the first eccentric portion 34A and the input side seal portion 60A, and between the second rolling portion 40B of the second eccentric portion 34B and the non-input side seal portion 60B.

[0068] The advantage of this will be explained. Consider the flow from the end of the preceding process of the first or second process until the start of the subsequent process. The position where the head 94 should be when the preceding process is completed is called the preceding process end position, and the position where the head 94 should be when the subsequent process is started is called the subsequent process start position. After the preceding process is completed and before the subsequent process is started, the relative positions of the head 94 and the rotating body 12 must be changed from the preceding process end position to the subsequent process start position. Here, the preceding process end position is radially outward of the area where the laser light was re-irradiated in the preceding process (see, for example, FIG. 7(b)). Furthermore, the start position of the subsequent process is radially outward of the area to be re-irradiated with laser light in the subsequent process (see, for example, FIG. 7(d)). As described above, if the circumferential positions of the area to be re-irradiated with laser light in the first process and the area to be re-irradiated with laser light in the second process are aligned, the amount of relative movement of the head 94 and the rotor 12 in the circumferential direction between the preceding process and the subsequent process can be significantly reduced compared to when these circumferential positions are significantly misaligned. This in turn allows the working time of the heat treatment process to be shortened, and manufacturing costs to be reduced by improving manufacturing efficiency.

[0069] In relation to such effects, the width Wa of the line formed by the first low-hardness regions 74 of the rolling portions 40A, 40B and the first low-hardness regions 74 of the sealing portions 60A, 60B is preferably, for example, 5 mm or less, and more preferably 2 mm or less. The lower limit of the width Wa is preferably 1 mm or more. The width Wb of the line formed by the re-irradiated portion also preferably satisfies the same condition.

[0070] The effects of the reduction gear device 10 described above will now be described.

[0071] (A) A high-hardness region 72 is formed in the seal portions 60A, 60B of the rotor 12 by laser hardening, and a second low-hardness region 76 is formed on the outer surface of the rotor 12. Therefore, after heat treatment by laser hardening, there is no need for finish processing to remove thermal strain on the second low-hardness region 76. Consequently, compared to when the entire rotor 12 is hardened, the range of finish processing for the high-hardness region 72 can be reduced. As a result, manufacturing costs can be reduced.

[0072] (B) The second low hardness region 76 of the rotating body 12 is provided in the outer periphery intermediate portion 64 between the rolling portions 40A, 40B and the seal portions 60A, 60B. Therefore, the finishing process for removing thermal strain, which is required in the high hardness region 72, is not required in the outer periphery intermediate portion 64. Consequently, the manufacturing cost can be reduced.

[0073] (C) The circumferential positions of the first low hardness regions 74 of the seal portions 60A, 60B are aligned with the circumferential positions of the first low hardness regions 74 of the rolling portions 40A, 40B. As described above, the amount of relative movement in the circumferential direction between the head 94 and the rotating body 12 from the preceding process to the succeeding process can be significantly reduced. This in turn allows for a reduction in manufacturing costs.

[0074] (D) The bearing arrangement portions 62A, 62B of the outer circumferential intermediate portion 64 are provided in the second low hardness region 76. Therefore, the finishing process required for removing thermal strain in the high hardness region 72 is not required in the bearing arrangement portions 62A, 62B.

[0075] (E) When assembling the input bearings 30A, 30B to the rotating body 12, the input bearings 30A, 30B are positioned in the bearing arrangement portions 62A, 62B by moving them from the axial outside of the rotating body 12 toward the bearing arrangement portions 62A, 62B. If the difference in radius between the seal portions 60A, 60B and the bearing arrangement portions 62A, 62B is 2 mm or less, moving the input bearings 30A, 30B in this manner may result in the input bearings 30A, 30B hitting the seal portions 60A, 60B and causing dents. In this regard, according to this embodiment, the seal portions 60A, 60B of the rotating body 12 are provided with high-hardness regions 72. This reduces the occurrence of dents in the seal portions 60A, 60B when assembling the input bearings 30A, 30B. This is particularly advantageous in that it reduces the amount of finish machining required for the high-hardness regions 72, as described above, while also reducing the occurrence of dents.

[0076] (F) The hollow portion 66 is provided in the second low hardness region 76. Therefore, the finishing process required for removing thermal strain in the high hardness region 72 is not required in the hollow portion 66.

[0077] (G) The bolt holes 68 are provided in the second low-hardness regions 76. Therefore, the bolt holes 68 can be formed in the second low-hardness regions 76, not in the high-hardness regions 72. Therefore, compared to when the entire rotating body 12 is hardened, the locations where holes need to be drilled for the bolt holes 68 can be located in locations that are easier to drill (the second low-hardness regions 76).

[0078] (Second embodiment) See Figure 8. The reduction gear 10 of this embodiment is a flexible mesh type reduction gear 10 that includes an exciter shaft 100, which is a rotating body 12. The flexible mesh type reduction gear 10 also includes a flexure gear 102 that is flexibly deformed by the exciter shaft 100, and a gear bearing 18 that is arranged between the exciter shaft 100 and the flexure gear 102. The reduction gear 10 also includes an external gear 20 and internal gears 22A, 22B that mesh with each other, one of which constitutes the flexure gear 102, a casing 24 that is arranged on the outer periphery of the flexure gear 102, and carriers 26A, 26B that are provided axially laterally relative to the external gear 20. The reduction gear 10 also includes oil seals 28A, 28B arranged between the carriers 26A, 26B and the vibrator shaft 100, and input bearings 30A, 30B arranged between the carriers 26A, 26B and the vibrator shaft 100. In the reduction gear 10 of this embodiment, the external gear 20 is a flexible gear 102. The reduction gear 10 of this embodiment is a cylindrical flexible mesh type reduction gear that uses multiple internal gears 22A, 22B. Hereinafter, the direction along the rotation center line CL1 of the rotating body 12 (vibrator shaft 100) is referred to as the axial direction X.

[0079] The vibrator shaft 100 can be rotated by rotational power transmitted from a drive unit (not shown). The vibrator shaft 100 has enough rigidity to flexibly deform the flexible gear 102 by its own rotation. The vibrator shaft 100 includes a vibrator 104 that flexibly deforms the flexible gear 102, and shaft portions 106 provided on both axial sides of the vibrator 104. The outer periphery of the vibrator 104 is elliptical in a cross section perpendicular to the axial direction of the vibrator shaft 100. In this specification, the term "ellipse" is not limited to a geometrically strict ellipse, but also includes an approximate ellipse. The outer periphery of the shaft portion 106 is circular in a cross section perpendicular to the axial direction of the vibrator shaft 100.

[0080] The flexure gear 102 is a flexible cylindrical member and is rotatably supported by a vibration exciter 104 via a gear bearing 18.

[0081] The gear bearings 18 of this embodiment correspond to each of the multiple internal gears 22A, 22B and are individually arranged inside the corresponding internal gears 22A, 22B. The gear bearings 18 include multiple rolling elements 36 arranged between the flexible gear 102 and the vibrator 104 of the vibrator shaft 100, a retainer 38 that maintains the relative positions of the multiple rolling elements 36, and a flexible outer ring 108 that is arranged on the outer periphery of the multiple rolling elements 36. The rolling elements 36 of this embodiment are rollers. The gear bearings 18 do not include a dedicated inner ring. Instead, the vibrator 104 doubles as the inner ring, and the vibrator shaft 100 includes a rolling portion 40C on which the rolling elements 36 roll. The rolling portion 40C is formed by the outer periphery of the vibrator 104. The outer ring 108 is a flexible cylindrical member, similar to the flexure gear 102 , and is flexibly deformed by the vibrator 104 .

[0082] The internal gears 22A, 22B are arranged on the outer periphery of the external gear 20. The internal gears 22A, 22B have enough rigidity not to deform following the rotation of the vibration exciter shaft 100. The internal gears 22A, 22B of this embodiment include an input side internal gear 22A arranged on the input side, and a counter-input side internal gear 22B arranged on the counter-input side.

[0083] The casing 24 houses other components of the reduction gear 10, such as the flexure gear 102. The casing 24 includes a first casing member 110 that also serves as the input side internal gear 22A, and a second casing member 112 that is disposed on the outer periphery of the non-input side internal gear 22B.

[0084] The carriers 26A, 26B include an input side carrier 26A arranged on the axial input side of the external gear 20, and a counter-input side carrier 26B arranged on the axial counter-input side. The input side carrier 26A is integrated with the input side internal gear 22A. The counter-input side carrier 26B is integrated with the counter-input side internal gear 22B.

[0085] As in the first embodiment, the oil seals 28A, 28B include an input side oil seal 28A and a counter-input side oil seal 28B. The input side oil seal 28A is disposed between the input side carrier 26A and the rotor 12 (shaft portion 106 of the vibrator shaft 100). The counter-input side oil seal 28B is disposed between the counter-input side carrier 26B and the rotor 12 (shaft portion 106 of the vibrator shaft 100). The configuration of the oil seals 28A, 28B is the same as in the first embodiment.

[0086] Similar to the first embodiment, the input bearings 30A, 30B include an input side input bearing 30A and a counter input side input bearing 30B. The input side input bearing 30A is disposed between the input side carrier 26A and the rotating body 12 (shaft portion 106 of the vibrator shaft 100). The counter input side input bearing 30B is disposed between the counter input side carrier 26B and the rotating body 12 (shaft portion 106 of the vibrator shaft 100). The configuration of the input bearings 30A, 30B is similar to that of the first embodiment.

[0087] The output member rotates in synchronization with the rotation component of one of the external gear 20 and the internal gears 22A, 22B (the external gear 20 in this embodiment), thereby outputting the rotation component to the driven device. One of the output member and the fixed member is the non-input side carrier 26B, and the other is the casing 24. When the non-input side carrier 26B serves as the output member, the external gear 20 rotates together with the non-input side internal gear 22B, and when the casing 24 serves as the output member, the external gear 20 rotates together with the input side internal gear 22A.

[0088] The operation of the reduction gear 10 described above will now be described. When rotational power is transmitted from the driving device to the vibrator shaft 100, the vibrator shaft 100 rotates. As the vibrator shaft 100 rotates, the flexible gear 102 is flexibly deformed to form an ellipse that matches the shape of the vibrator 104 of the vibrator shaft 100. This causes the meshing positions of the external gear 20 and the internal gear 22 to shift sequentially in the circumferential direction. As a result, one of the external gear 20 and the internal gears 22A, 22B (the external gear 20 in this embodiment) rotates together with the output member. The rotation of the vibrator shaft 100 is reduced at a reduction ratio corresponding to the external gear 20 and the internal gears 22A, 22B, and is then output to the driven device via the output member.

[0089] Refer to Figure 9. Similar to the first embodiment, the rotating body 12, which is the vibrator shaft 100, includes, in addition to the rolling portion 40C described above, seal portions 60A, 60B with which the oil seals 28A, 28B come into contact, and bearing arrangement portions 62A, 62B in which the input bearings 30A, 30B are arranged.

[0090] As in the first embodiment, the seal portions 60A, 60B include an input-side seal portion 60A and a non-input-side seal portion 60B. As in the first embodiment, the bearing arrangement portions 62A, 62B include an input-side bearing arrangement portion 62A and a non-input-side bearing arrangement portion 62B. The bearing arrangement portions 62A, 62B are provided in an outer circumferential intermediate portion 64 that is provided between the rolling portion 40C and the seal portions 60A, 60B.

[0091] The difference in radius between the seal portions 60A, 60B located axially outward of the bearing arrangement portions 62A, 62B and the bearing arrangement portions 62A, 62B is 2 mm or less, as in the first embodiment.

[0092] Similar to the first embodiment, the rotor 12 also includes a hollow portion 66 and a bolt hole 68. Unlike the first embodiment, the bolt hole 68 is arranged at a position that radially overlaps with the input side seal portion 60A.

[0093] 9 and 10(a) to 10(c), in which the high hardness region 72 is double-hatched, the first low hardness region 74 is single-hatched, and the second low hardness region 76 is not hatched.

[0094] Similar to the first embodiment, a high hardness region 72 and low hardness regions 74, 76 are provided on the outer surface of the rotating body 12. Similar to the first embodiment, the high hardness region 72 is provided in the seal portions 60A, 60B and the rolling portion 40C, which form the outer surface of the rotating body 12. Similar to the first embodiment, the low hardness regions 74, 76 include a first low hardness region 74 provided in the seal portions 60A, 60B and the rolling portion 40C, and a second low hardness region 76 provided in a location different from the seal portions 60A, 60B and the rolling portion 40C.

[0095] The first low-hardness regions 74 of the seal portions 60A, 60B and the rolling portion 40C are provided in the same manner as in the first embodiment. The second low-hardness regions 76 are provided, for example, in the outer circumferential intermediate portion 64, the hollow portion 66, and the axial end portion of the rotating body 12.

[0096] The hardness of the high hardness region 72, the first low hardness region 74, and the second low hardness region 76 and the method for providing them are the same as those in the first embodiment. For example, the high hardness region 72 is provided by laser hardening.

[0097] See Figure 10(b). A line extending from the rotation center line CL1 of the vibrator shaft 100 along the major axis direction Da of the vibrator 104 is defined as a first reference line Lc1, and a line extending from the rotation center line CL1 along the minor axis direction Db is defined as a second reference line Lc2. The major axis direction Da refers to the direction along the major axis of the ellipse formed by the cross-sectional shape of the vibrator 104. The minor axis direction Db refers to the direction along the minor axis of the ellipse formed by the cross-sectional shape of the vibrator 104. The cross-sectional shape of the vibrator 104 here refers to the shape of a cross section perpendicular to the rotation center line CL1.

[0098] Within the range around the rotation center line CL1 of the vibrator 104, the range of ±45 degrees from the first reference line Lc1 is referred to as the high load range Sb1, and the range of ±45 degrees from the second reference line Lc2 is referred to as the low load range Sb2. The highest load is applied to the vibrator 104 in the high load range Sb1, and almost no load is applied in the low load range Sb2. The low load range can be considered to be the range within the entire circumferential range of the rolling part 40C where the load on the rolling part 40C is low.

[0099] The first low hardness region 74 of the rolling part 40C is provided within the low load range Sb2. The entire first low hardness region 74 of the rolling part 40C is provided so as to fall within the low load range Sb2. The high hardness region 72 is provided throughout the high load range Sb1 and in a location other than the first low hardness region 74 in the low load range Sb2.

[0100] The circumferential positions of the first low hardness regions 74 of the seal portions 60A, 60B are aligned with the circumferential positions of the first low hardness regions 74 of the rolling portion 40C. In the flexible mesh reduction gear 10, the circumferential positions of the seal portions 60A, 60B and the rolling portion 40C refer to positions in the circumferential direction of a circle centered on the rotation center line CL1 of the rotating body 12. The definition of "aligned" is the same as in the first embodiment.

[0101] The manufacturing process for obtaining the above-described rotor 12 (vibrator shaft 100) is the same as that of the first embodiment. That is, the vibrator shaft 100 can be obtained by going through the rough machining step S20 → pre-machining steps (finishing step S22, hole drilling step S24) → heat treatment step S26 → finishing step S28 in this order.

[0102] The heat treatment method used in the heat treatment step S26 performed on the rotor 12 (vibrator shaft 100) is the same as that in the first embodiment. That is, this heat treatment method also includes a first step of heat treating the rolling portion 40C and a second step of heat treating the seal portions 60A and 60B.

[0103] In either the first step or the second step, the rotor 12 may be chucked at any point by a chuck device.

[0104] In the first step, as in the first embodiment, the irradiation position of the laser light is changed in the circumferential direction to harden the rolling portion 40C over the entire circumference of the vibrator shaft 100, and then the laser light is re-irradiated onto a portion of the area that has already been irradiated with the laser light.

[0105] In the second step, as in the first embodiment, the irradiation position of the laser light is changed in the circumferential direction to harden the sealing portions 60A, 60B over the entire circumference of the rotating body 12, and then the laser light is re-irradiated onto a portion of the area that has already been irradiated with the laser light.

[0106] As in the first embodiment, the circumferential positions of the laser beam re-irradiation points on the rolling portion 40C in the first step and the circumferential positions of the laser beam re-irradiation points on the sealing portions 60A, 60B in the second step are aligned. This allows the working time for the heat treatment process to be shortened, and manufacturing costs to be reduced by improving manufacturing efficiency, as in the first embodiment.

[0107] The reduction gear 10 of this embodiment also includes the components (not shown) described above in (A) to (G), and provides the effects corresponding to those described therein.

[0108] Other variations of each component are described.

[0109] The eccentric oscillating reduction gear 10 may be a distribution type in which multiple crankshafts 14 are arranged at positions radially offset from the central axis of the internal gear 22. The eccentric oscillating reduction gear 10 may be an internal oscillating type in which the internal gear 22 serves as the oscillating gear 16.

[0110] In the flexible mesh reduction gear 10, the internal gear 22 may be a flexible gear 102. Furthermore, there are no particular limitations on the type of flexible mesh reduction gear 10. For example, it may be a cup-type or top hat-type flexible mesh reduction gear with one internal gear.

[0111] To obtain the effect of (A), the high hardness regions 72 do not have to be provided in the rolling portions 40A, 40B, 40C of the rotating body 12. In addition, the first low hardness regions 74 do not have to be provided in the seal portions 60A, 60B of the rotating body 12. In addition, the circumferential positions of the first low hardness regions 74 do not have to be aligned between the rolling portions 40A, 40B, 40C of the rotating body 12 and the seal portions 60A, 60B.

[0112] To obtain the effect of (B), the first low-hardness regions 74 may not be provided in the rolling portions 40A, 40B, 40C and the seal portions 60A, 60B of the rotor 12. Alternatively, the high-hardness regions 72 of the rotor 12 may be provided by partial hardening other than laser hardening. Partial hardening here includes, for example, hardening performed outside a heating furnace, such as induction hardening, as well as hardening performed within a heating path with areas other than those to be heat-treated masked with anti-carburization treatment or the like. Furthermore, to obtain the effect of (B), the bearing arrangement portions 62A, 62B may not be provided in the outer circumferential intermediate portion 64 of the rotor 12.

[0113] To obtain the effect of (C), the outer circumferential intermediate portion 64 of the rotor 12 may be provided with a first low hardness region 74 and a high hardness region 72 instead of the second low hardness region 76. Alternatively, the high hardness region 72 of the rotor 12 may be provided by partial hardening other than laser hardening. Furthermore, to obtain the effect of (C), the first low hardness regions 74 of the rolling portions 40A, 40B and the seal portions 60A, 60B do not have to be linear. For example, these first low hardness regions 74 may be dot-shaped or the like.

[0114] The difference in radius between the seal portions 60A, 60B and the bearing arrangement portions 62A, 62B may be more than 2 mm.

[0115] The high hardness region 72 may also be provided in other locations in the seal portions 60A, 60B and the rolling portions 40A, 40B, 40C. In addition, at least one of the hollow portion 66 and the bolt hole 68 may be provided in the high hardness region 72.

[0116] In either the eccentric oscillating type reduction gear or the flexure mesh type reduction gear, the rotating body 12 does not have to have the hollow portion 66 or the bolt hole 68. Furthermore, in either of these reduction gears, the bolt hole 68 may be positioned so as to overlap radially with the seal portions 60A, 60B. Furthermore, in either of these reduction gears, the bolt hole 68 may be positioned so as to overlap radially with the seal portions 60A, 60B.

[0117] 6, the hole machining step S24 may be performed after the heat treatment step S26, rather than before. Additionally, the finish machining step S22, which targets areas other than the areas scheduled for heat treatment, may be performed after the heat treatment step S26, rather than before. In either case, machining of high-hardness areas can be eliminated for areas that do not require high hardness (bearing arrangement portions 62A, 62B, hollow portion 66, axial end portions, etc.).

[0118] The above-described embodiments and variations are merely examples. The abstract technical ideas should not be interpreted as being limited to the contents of the embodiments and variations. Many design changes are possible in the contents of the embodiments and variations, such as changing, adding, or deleting components. In the above-described embodiments, the contents that allow such design changes are emphasized by adding the notation "embodiment." However, design changes are also permitted even in contents that do not have such notation. Hatching on cross sections in the drawings does not limit the material of the hatched objects. [Explanation of symbols]

[0119] 10...reduction device, 12...rotating body, 14...crankshaft, 16...oscillating gear, 28A, 28B...oil seal, 30A, 30B...input bearing, 34A, 34B...eccentric portion, 36...rolling element, 40A, 40B, 40C...rolling portion, 60A, 60B...seal portion, 62A, 62B...bearing arrangement portion, 66...hollow portion, 68...bolt hole, 72...high hardness region, 74...first low hardness region, 76...second low hardness region, 100...vibrator shaft, 102...flexure gear, 104...vibrator.

Claims

1. An eccentric oscillating type reduction gear device having a crankshaft that is a rotating body, the rotating body includes an eccentric portion that oscillates the oscillating gear and a seal portion that comes into contact with an oil seal, The sealing portion is provided with a high-hardness region by laser hardening, a low hardness region having a lower hardness than the high hardness region is provided in the seal portion of the outer surface portion of the rotating body, The low hardness region of the seal portion is provided at the same circumferential position as a part of a low load range, in which the load on the eccentric portion is low, within the entire circumferential range of the eccentric portion.

2. A flexible meshing type reduction gear device having a vibrator shaft that is a rotating body, the rotating body includes a vibrator that flexibly deforms the deflection gear and a seal portion with which the oil seal comes into contact; The sealing portion is provided with a high-hardness region by laser hardening, a low hardness region having a lower hardness than the high hardness region is provided in the seal portion of the outer surface portion of the rotating body, A reduction gear transmission in which the low hardness region of the seal portion is provided at the same circumferential position as a part of a low load region in which the load on the vibrator is low within the entire circumferential range of the vibrator.

3. An eccentric oscillating type reduction gear device having a crankshaft that is a rotating body, the rotating body includes an eccentric portion that oscillates the oscillating gear, a rolling portion in which a rolling element disposed between the oscillating gear and the eccentric portion rolls, and a seal portion with which an oil seal comes into contact, Each of the rolling portion and the sealing portion is provided with a high hardness region and a low hardness region having a lower hardness than the high hardness region, the low hardness region of the rolling portion is provided within a low load range in the entire circumferential range of the rolling portion, where the load on the rolling portion is low; A reduction gear transmission, wherein the circumferential position of the low hardness region of the seal portion is aligned with the circumferential position of the low hardness region of the rolling portion.

4. A flexible meshing type reduction gear device having a vibrator shaft that is a rotating body, the rotating body includes a vibration exciter that flexibly deforms the flexure gear, a rolling portion in which a rolling element that is disposed between the flexure gear and the vibration exciter rolls, and a seal portion with which an oil seal comes into contact, Each of the rolling portion and the sealing portion is provided with a high hardness region and a low hardness region having a lower hardness than the high hardness region, the low hardness region of the rolling portion is provided within a low load range in the entire circumferential range of the rolling portion, where the load on the rolling portion is low; A reduction gear transmission, wherein the circumferential position of the low hardness region of the seal portion is aligned with the circumferential position of the low hardness region of the rolling portion.

5. The rotating body includes a hollow portion, The reduction gear transmission according to claim 1 , wherein the hollow portion is provided with the low hardness region.

6. the rotating body includes a bolt hole provided at an axial end of the rotating body, The reduction gear transmission according to claim 1 , wherein the bolt holes are provided in the low hardness region.

7. The reduction gear transmission according to claim 6 , wherein the bolt hole overlaps with the seal portion in the radial direction.

8. A method for heat treating a rotating body that is a crankshaft of an eccentric oscillating type reduction gear, comprising: the rotating body includes an eccentric portion that oscillates the oscillating gear, a rolling portion in which a rolling element that is disposed between the oscillating gear and the eccentric portion rolls, and a seal portion in which an oil seal is disposed, The heat treatment method includes: a first step of irradiating the laser beam again onto a part of the area already irradiated with the laser beam after hardening the entire circumferential range of the rolling portion by changing the irradiation position of the laser beam in a circumferential direction; a second step of irradiating the laser beam again onto a part of the area already irradiated with the laser beam after hardening the entire circumferential range of the sealing portion by changing the irradiation position of the laser beam in the circumferential direction, the re-irradiation area of ​​the laser light in the first step is set to fall within a low load range in the entire circumferential range of the rolling portion, where the load on the rolling portion is low; a heat treatment method in which the circumferential position of the laser beam re-irradiation portion in the rolling portion is aligned with the circumferential position of the laser beam re-irradiation portion in the sealing portion;

9. A heat treatment method for a rotating body that is a vibrator shaft of a flexible mesh type reduction gear device, comprising: the rotating body includes a vibration exciter that flexibly deforms the flexure gear, a rolling portion in which a rolling element that is disposed between the flexure gear and the vibration exciter rolls, and a seal portion with which an oil seal comes into contact, The heat treatment method includes: a first step of irradiating the laser beam again onto a part of the area already irradiated with the laser beam after hardening the entire circumferential range of the rolling portion by changing the irradiation position of the laser beam in a circumferential direction; a second step of irradiating the laser beam again onto a part of the area already irradiated with the laser beam after hardening the entire circumferential range of the sealing portion by changing the irradiation position of the laser beam in the circumferential direction, the re-irradiation area of ​​the laser light in the first step is set to fall within a low load range in the entire circumferential range of the rolling portion, where the load on the rolling portion is low; a heat treatment method in which the circumferential position of the laser beam re-irradiation portion in the rolling portion is aligned with the circumferential position of the laser beam re-irradiation portion in the sealing portion;

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