RPM REDUCERS AND HEAT TREATMENT PROCEDURES

Abstract

Speed ​​reducer (10) of the eccentrically oscillating type, comprising: a crankshaft (14) which is a rotating body (12), wherein the rotating body (12) contains a sealing section (60A, 60B) with which an oil seal (28A, 28B) comes into contact, a region (72) with high hardness is provided by laser quenching on the sealing section (60A, 60B), and a region (74, 76) with low hardness, which has a lower hardness than the region (72) with high hardness, is provided on an outer surface section of the body of revolution (12).

Description

BACKGROUND OF THE INVENTION Area of ​​the invention

[0001] The present disclosure relates to a speed reducer and a heat treatment process. Description of the state of the art

[0002] Japanese unexamined patent publication No. 2013-124730 discloses a speed reducer comprising a crankshaft, which is a rotating body. The rotating body includes a sealing section with which an oil seal comes into contact. SUMMARY OF THE INVENTION

[0003] The sealing section of the rotating body must exhibit high hardness due to the influence of the oil seal. This applies not only to a crankshaft used in an eccentrically oscillating speed reducer, but also to a shaft generator used as a rotating body in a bending-engagement speed reducer. A technique that reduces manufacturing costs while increasing the hardness of a sealing section of a rotating body, as described above, has not yet been proposed.

[0004] One purpose of the present disclosure is to provide a technique that makes it possible to reduce manufacturing costs.

[0005] According to one aspect of the present disclosure, an eccentrically oscillating speed reducer is provided, comprising a crankshaft which is a rotating body. The rotating body includes a sealing section with which an oil seal comes into contact, a high-hardness region is provided on the sealing section by laser quenching, and a low-hardness region, which has a lower hardness than that of the high-hardness region, is provided on an outer surface section of the rotating body.

[0006] According to another aspect of the present disclosure, a speed reducer of the bending-engagement type is provided, comprising a shaft generator shaft which is a rotating body. The rotating body includes a sealing section with which an oil seal comes into contact, a high-hardness region is provided on the sealing section by laser quenching, and a low-hardness region, which has a lower hardness than that of the high-hardness region, is provided on an outer surface section of the rotating body.

[0007] According to yet another aspect of the present disclosure, an eccentrically oscillating speed reducer is provided, comprising a crankshaft which is a rotating body. The rotating body includes an eccentric section that causes an oscillating gear to oscillate, a rolling section on which a rolling element arranged between the oscillating gear and the eccentric section rolls, and a sealing section with which an oil seal comes into contact. A region of high hardness is provided on both the rolling section and the sealing section, and a region of low hardness, having a lower hardness than that of the region of high hardness, is provided on an outer surface section of the rotating body between the rolling section and the sealing section.

[0008] According to yet another aspect of the present disclosure, a speed reducer of the bending-engagement type is provided, comprising a shaft generator shaft which is a rotating body. The rotating body includes a shaft generator which bends and deforms a flexible gear, a rolling section on which a rolling element arranged between the flexible gear and the shaft generator rolls, and a sealing section with which an oil seal comes into contact. A high-hardness region is provided on both the rolling section and the sealing section, and a low-hardness region, having a lower hardness than the high-hardness region, is provided on an outer surface section of the rotating body between the rolling section and the sealing section.

[0009] According to yet another aspect of the present disclosure, a speed reducer of the eccentrically oscillating type is provided, comprising a crankshaft which is a rotating body.The rotating body includes an eccentric section that causes an oscillating gear to oscillate, a rolling section on which a rolling element arranged between the oscillating gear and the eccentric section rolls, and a sealing section with which an oil seal comes into contact. A high-hardness region and a linear low-hardness region, which has a lower hardness than the high-hardness region, are provided on both the rolling section and the sealing section. The low-hardness region of the rolling section is located within a low-load area, where the load on the rolling section is low across its entire circumference. A circumferential position of the low-hardness region of the sealing section is aligned with a circumferential position of the low-hardness region of the rolling section.

[0010] According to yet another aspect of the present disclosure, a speed reducer of the bending engagement type is provided, comprising a shaft generator shaft which is a rotating body.The rotating body includes a shaft generator that bends and deforms a flexible gear, a rolling section on which a rolling element arranged between the flexible gear and the shaft generator rolls, and a sealing section with which an oil seal comes into contact. A high-hardness region and a low-hardness region, which has a lower hardness than the high-hardness region, are provided on both the rolling section and the sealing section. The low-hardness region of the rolling section is located within a low-load area, where the load on the rolling section is low across its entire circumference. A circumferential position of the low-hardness region of the sealing section is aligned with a circumferential position of the low-hardness region of the rolling section.

[0011] According to yet another aspect of the present disclosure, a heat treatment method is provided for a rotating body, which is a crankshaft of a speed reducer of the eccentrically oscillating type, wherein the rotating body comprises an eccentric section that causes an oscillating gear to oscillate, a rolling section on which a rolling element arranged between the oscillating gear and the eccentric section rolls, and a sealing section on which an oil seal is arranged, wherein the heat treatment method comprises a first step of re-irradiating with laser light a section of an area irradiated with the laser light after the rolling section has been quenched over an entire circumferential area by changing an irradiation position of the laser light in a circumferential direction, and a second step of re-irradiating with the laser light a section of an area irradiated with the laser light.after the sealing section has been quenched over its entire circumference by changing the laser light irradiation position in the circumferential direction. A section re-irradiated with the laser light in the first step has a linear shape and is set within a low-load region, where the load on the rolling section is low over its entire circumference, and a circumferential position of a laser-irradiated section of the rolling section is aligned with a circumferential position of a laser-irradiated section of the sealing section.

[0012] According to yet another aspect of the present disclosure, a heat treatment method is provided for a rotating body, which is a shaft generator shaft of a speed reducer of the bending engagement type, wherein the rotating body comprises a shaft generator that bends and deforms a flexible gear, a rolling section on which a rolling element arranged between the flexible gear and the shaft generator rolls, and a sealing section with which an oil seal comes into contact, wherein the heat treatment method comprises a first step of re-irradiating with laser light a section of an area irradiated with the laser light after the rolling section has been quenched over an entire circumferential area by changing an irradiation position of the laser light in a circumferential direction, and a second step of re-irradiating with the laser light a section of an area irradiated with the laser light.after the sealing section has been quenched over its entire circumference by changing the laser light irradiation position in the circumferential direction. A section re-irradiated with the laser light in the first step has a linear shape and is set within a low-load region, where the load on the rolling section is low over its entire circumference, and a circumferential position of a laser-irradiated section of the rolling section is aligned with a circumferential position of a laser-irradiated section of the sealing section.

[0013] According to the aspects of the present disclosure, it is possible to reduce manufacturing costs. BRIEF DESCRIPTION OF THE FIGURES Fig. Figure 1 is a side section view of a speed reducer of a first embodiment. Fig. Figure 2 is a side section view showing a crankshaft of the first embodiment together with a structure in its vicinity. Fig. 3A to 3D are sectional views, where Fig. 3A a sectional view along line AA in Fig. 2 is, Fig. 3B a section view along line BB in Fig. 2 is, Fig. 3C a section view along line CC in Fig. 2 is and Fig. 3D section view along line DD in Fig. 2 is. Fig. Figure 4 is a graph showing a relationship between depth of a surface in region 72 with high hardness and Vickers hardness. Fig. Figure 5 is a process diagram showing a manufacturing process for obtaining a revolved body of a reference example. Fig. Figure 6 is a process diagram showing a manufacturing process for obtaining a body of revolution of the first embodiment. Fig. 7A to 7D are schematic views, where Fig. 7A is a schematic view showing a state in which a first step of the first embodiment is underway, Fig. Figure 7B is a schematic view showing a state where re-irradiation with laser light is performed in the first step. Fig. 7C is a schematic view showing a state where a second step is in progress, and Fig. 7D is a schematic view showing a state where re-irradiation with laser light is performed in the second step. Fig. Figure 8 is a side section view of a speed reducer of a second embodiment. Fig. Figure 9 is a side section view showing a wave generator shaft of the second embodiment together with a structure in its vicinity. Fig. 10A to 10C are sectional views, where Fig. 10A a section view along line EE in Fig. 9 is, Fig. 10B a section view along line FF in Fig. 9 is and Fig. 10C a section view along line GG in Fig. 9 is. DETAILED DESCRIPTION OF THE INVENTION

[0014] The following are descriptions of embodiments. Identical components are given the same reference numerals, and repeated descriptions are omitted. In each drawing, components are omitted, enlarged, or reduced as appropriate to simplify the description. The drawings are to be viewed in the directions indicated by the reference numerals. (First embodiment)

[0015] The description is given with reference to Fig. 1. A speed reducer 10 is an eccentrically oscillating type speed reducer comprising a crankshaft 14, which is a rotating body 12. Furthermore, the speed reducer 10 includes an oscillating gear 16, which is set into oscillation by the crankshaft 14, and gear bearings 18 arranged between the crankshaft 14 and the oscillating gear 16. The speed reducer 10 also includes meshing external gears 20 and an internal gear 22, a housing 24 located near the outer circumferential sides of the oscillating gears 16, and supports 26A and 26B provided on lateral sides with respect to the external gears 20 in an axial direction, with the external gears 20 or the internal gear 22 serving as the oscillating gears 16.Furthermore, the speed reducer 10 includes oil seals 28A and 28B, which are arranged between the supports 26A and 26B and the crankshaft 14, and input bearings 30A and 30B, which are also arranged between the supports 26A and 26B and the crankshaft 14. The speed reducer 10 of the present embodiment is an external gear oscillation type speed reducer, in which the external gears 20 serve as the oscillating gears 16. Hereinafter, a direction along a rotational centerline CL1 of the rotating body 12 is referred to as an axial direction X. Furthermore, for the sake of simplicity, a side (right side in ) is referred to below. Fig. 1) in the axial direction X is designated as one input side, and the other side (left side in Fig. 1) is referred to as a counter-entrance side.

[0016] The crankshaft 14 can be rotated by means of a torque transmitted by a drive device (not shown). The drive device is, for example, a motor, a geared motor, a machine, or the like. The speed reducer 10 in the present embodiment is a center-crank type speed reducer in which the crankshaft 14 is located on the same axis as a center axis CL2 of the internal gear 22.

[0017] The crankshaft 14 comprises a shaft section 32, to which torque is transmitted from the drive device, and several eccentric sections 34A and 34B, which can rotate integrally with the shaft section 32. The eccentric sections 34A and 34B are provided as part of the same element as the shaft section 32.

[0018] An outer circumferential surface of each of the eccentric sections 34A and 34B forms a circle. Each of the axial centers CL3 of the eccentric sections 34A and 34B is offset from the centerline CL1 of rotation of the crankshaft 14 by an eccentricity amount e. The eccentric sections 34A and 34B can cause the oscillating gears 16 to oscillate by rotating about the centerline CL1 of rotation of the crankshaft 14. The multiple eccentric sections 34A and 34B comprise a first eccentric section 34A and a second eccentric section 34B. The phases of the eccentric sections 34A and 34B, which are adjacent to each other in a maximum eccentric direction (described later), are offset from each other by 360° / (number of eccentric sections 34A and 34B) (in the present embodiment, offset by 180°). The number of eccentric sections 34A and 34B is not particularly limited and can be one, three, or more.

[0019] The oscillating gears 16 are provided separately to correspond to the multiple eccentric sections 34A and 34B of the crankshaft 14 and are supported by the corresponding eccentric sections 34A and 34B via the gear bearings 18.

[0020] The gear bearings 18 are provided separately to correspond to the multiple oscillating gears 16 and the multiple eccentric sections 34A and 34B, and are arranged between the respective oscillating gears 16 and the eccentric sections 34A and 34B. The gear bearings 18 include multiple rolling elements 36, which are arranged between the oscillating gears 16 and the eccentric sections 34A and 34B of the crankshaft 14, and retainers 38, which maintain the relative positions of the multiple rolling elements 36. The rolling elements 36 of the present embodiment are rollers. The gear bearings 18 do not include dedicated inner rings. Instead, the eccentric sections 34A and 34B also serve as inner rings, and the crankshaft 14 contains rolling sections 40A and 40B on which the rolling elements 36 roll. The rolling sections 40A and 40B are constructed from outer circumferential sections of the eccentric sections 34A and 34B.The rolling sections 40A and 40B comprise a first rolling section 40A, which is formed from an outer circumferential section of the first eccentric section 34A, and a second rolling section 40B, which is formed from an outer circumferential section of the second eccentric section 34B. The gear bearings 18 do not contain dedicated outer rings. Instead, the inner circumferential surfaces of the through holes of the oscillating gears 16 also serve as outer rings.

[0021] The internal gear 22 is integrated with the housing 24. The housing 24 accommodates other components of the speed reducer 10, such as the oscillating gear 16.

[0022] The carriers 26A and 26B comprise an input-side carrier 26A, which is arranged on the input side with respect to the external gears 20, and a counter-input-side carrier 26B, which is arranged on the counter-input side with respect to the external gears 20. The carriers 26A and 26B are integrated with an internal pin 42 that penetrates the external gears 20.

[0023] The oil seals 28A and 28B comprise an inlet-side oil seal 28A, located on the inlet side with respect to the gear bearings 18, and a counter-inlet-side oil seal 28B, located on the counter-inlet side with respect to the gear bearings 18. The inlet-side oil seal 28A is located between the inlet-side support 26A and the rotating body 12. The counter-inlet-side oil seal 28B is located between the counter-inlet-side support 26B and the rotating body 12.

[0024] The oil seals 28A and 28B seal a sealed chamber 44 in which the external gears 20 and the internal gear 22 are arranged. The sealed chamber 44 is filled with a lubricant (not shown) used to lubricate the external gears 20 and the internal gear 22. The oil seals 28A and 28B comprise adapted sections 46 that are press-fitted to the supports 26A and 26B or to the rotating body 12, and lip sections 48 that slide on each other between the supports 26A and 26B and the rotating body 12. In the present embodiment, the adapted sections 46 are attached to the supports 26A and 26B, and the lip sections 48 slide on the rotating body 12.

[0025] The input bearings 30A and 30B each comprise an input-side input bearing 30A, located on the input side relative to the gear bearings 18, and a counter-input-side input bearing 30B, located on the opposite input side relative to the gear bearings 18. The input-side input bearing 30A is located between the input-side support 26A and the rotating body 12. The counter-input-side input bearing 30B is located between the counter-input-side support 26B and the rotating body 12. The input bearings 30A and 30B are rolling bearings, such as ball bearings. In addition to several rolling elements, the input bearings 30A and 30B also contain dedicated outer and inner rings.

[0026] An element that outputs rotational force to a driven device is called a driven element, and an element that is to be fixed to an external element to support the speed reducer 10 is called a fixed element. The driven element rotates synchronously with an axial rotational component of the external gears 20 or the internal gear 22 to output the axial rotational component to the driven device. One of the driven element and fixed element consists of the supports 26A and 26B, and the other of the driven element and fixed element is the housing 24. In a case where the supports 26A and 26B serve as the driven element, the external gears 20 are rotated, and in a case where the housing 24 serves as the driven element, the internal gear 22 is rotated.

[0027] The operation of the speed reducer 10 described above is described. In a case where torque is transmitted from the drive device to the crankshaft 14, the crankshaft 14 rotates about the center line CL1, and the eccentric sections 34A and 34B cause the oscillating gears 16 to oscillate. During this oscillation, the positions at which the outer gears 20 and the inner gear 22 mesh are sequentially displaced in a circumferential direction. As a result, either the outer gears 20 or the inner gear 22 rotates with the output element. In this case, rotation of the crankshaft 14 is transmitted to the driven device via the output element after it has undergone a speed reduction with a reduction ratio corresponding to the outer gears 20 and the inner gear 22.

[0028] The description is given with reference to Fig. 2. The rotating body 12, which is the crankshaft 14, includes, in addition to the rolling sections 40A and 40B described above, sealing sections 60A and 60B, which come into contact with the oil seals 28A and 28B, and bearing assembly sections 62A and 62B, on which the input bearings 30A and 30B are arranged. The sealing sections 60A and 60B and the bearing assembly sections 62A and 62B are provided on an outer circumferential section of the rotating body 12.

[0029] Sealing sections 60A and 60B each comprise an inlet-side sealing section 60A, which contacts the inlet-side oil seal 28A, and a counter-inlet-side sealing section 60B, which contacts the counter-inlet-side oil seal 28B. In a case where the lip sections 48 of the oil seals 28A and 28B slide on the rotating body 12, the sections of the rotating body 12 where the lip sections 48 contact the rotating body 12 (where lip sections 48 slide on the rotating body 12) are the sealing sections 60A and 60B. On the other hand, in a case where the adapted sections 46 of the oil seals 28A and 28B are attached to the crankshaft 14, the sections of the crankshaft 14 where the adapted sections 46 come into contact with the crankshaft 14 are the sealing sections 60A and 60B.

[0030] The bearing arrangement sections 62A and 62B comprise an inlet-side bearing arrangement section 62A, on which the inlet-side inlet bearing 30A is arranged, and a counter-inlet-side bearing arrangement section 62B, on which the counter-inlet-side inlet bearing 30B is arranged. The bearing arrangement sections 62A and 62B are provided on outer circumferential intermediate sections 64, which are provided between the rolling sections 40A and 40B and the sealing sections 60A and 60B.

[0031] A difference between the radius of the sealing sections 60A and 60B, which are arranged axially outside the bearing assembly sections 62A and 62B, and the radius of the bearing assembly sections 62A and 62B is equal to or less than 2 mm. That is, a difference between the radius of the inlet-side sealing section 60A and the radius of the inlet-side bearing assembly section 62A is equal to or less than 2 mm, and a difference between the radius of the opposite-inlet-side sealing section 60B and the radius of the opposite-inlet-side bearing assembly section 62B is equal to or less than 2 mm. In the present embodiment, the differences between the radii are zero. The "difference between radii" here means a difference between radii with respect to the outside diameters of the two aforementioned sections.

[0032] Furthermore, the rotating body 12 includes a hollow section 66 which is open at axial end sections of the rotating body 12, screw holes 68 which are provided at an axial end section of the rotating body 12, and a clamping target section 70 which is to be clamped by a clamping device.

[0033] The hollow section 66 of the present embodiment penetrates the crankshaft 14 in the axial direction X. Screws (not shown) for connection to a counter device, such as the drive device, are screwed into the screw holes 68. The screw holes 68 are open at an axial end face of the crankshaft 14. The screw holes 68 are arranged in positions closer to the inlet side than the inlet-side sealing section 60A in order not to overlap the inlet-side sealing section 60A in a radial direction. The clamping target section 70 is provided on an outer circumferential section of the rotating body 12 outside the inlet-side sealing section 60A in the axial direction.

[0034] The description is given with reference to Fig. 2 and Fig. 3A to 3D. In the drawings, regions 72 with high hardness, which are described later, are double hatched, first regions 74 with low hardness are single hatched, and second regions 76 with low hardness are not shown hatched.

[0035] The high-hardness regions 72 are provided on outer surface sections of the rotating body 12. Specifically, the high-hardness regions 72 are located on the sealing sections 60A and 60B and the rolling sections 40A and 40B, which are considered outer surface sections of the rotating body 12. The high-hardness region 72 extends over a circumferential area of ​​each of the sealing sections 60A and 60B and the rolling sections 40A and 40B of the rotating body 12. The high-hardness regions 72 of the rolling sections 40A and 40B are provided to improve the fatigue strength of the rolling elements 36 against rolling fatigue.In a case where the lip sections 48 of the oil seals 28A and 28B slide on the sealing sections 60A and 60B as in the present embodiment, the high-hardness regions 72 of the sealing sections 60A and 60B are provided to prevent abrasion caused by the lip sections 48 sliding on the sealing sections 60A and 60B. On the other hand, in a case where the adapted sections 46 of the oil seals 28A and 28B are attached to the sealing sections 60A and 60B, the high-hardness regions 72 of the sealing sections 60A and 60B are provided to withstand the elastic restoring force of the oil seals 28A and 28B.

[0036] The outer surface sections of the body of revolution 12 are provided with regions 74 and 76 of low hardness, the hardness of which is lower than that of the high-hardness regions 72. The hardness of the outer surface sections here refers to Vickers hardness, measured by a method conforming to JIS Z2244. The hardness is the average of all hardnesses measured at intervals of a predetermined unit depth (for example, 0.1 mm) with respect to a predetermined area (for example, 1.0 mm) in one depth direction (normal direction) from an outer surface of said section. A difference between the hardness of the high-hardness regions 72 of the outer surface sections and the hardness of the low-hardness regions 74 and 76 is, for example, 50 HV or more in Vickers hardness.

[0037] The low-hardness regions 74 and 76 include the first low-hardness regions 74, which are provided on the sealing sections 60A and 60B and on the rolling sections 40A and 40B, and the second low-hardness regions 76, which are provided on sections other than the sealing sections 60A and 60B and the rolling sections 40A and 40B.

[0038] The first regions 74 with low hardness of sealing sections 60A and 60B are partially located on sections of sealing sections 60A and 60B that do not contain the regions 72 with high hardness. Sealing sections 60A and 60B are provided with the regions 72 with high hardness and the first regions 74 with low hardness.

[0039] The first regions 74 with low hardness of rolling sections 40A and 40B are partially located on sections of rolling sections 40A and 40B that do not contain the regions 72 with high hardness. Rolling sections 40A and 40B are provided with the regions 72 with high hardness and the first regions 74 with low hardness.

[0040] The second regions 76 with low hardness are provided, for example, on the outer circumferential intermediate sections 64, the axial end sections, the hollow section 66, and the clamping target section 70 of the rotating body 12. The second regions 76 with low hardness of the outer circumferential intermediate sections 64 extend over areas that run continuously across the entire circumference of the outer circumferential intermediate sections 64. It can be said that the second regions 76 with low hardness extend over areas that run continuously across the entire circumference of the bearing arrangement sections 62A and 62B of the outer circumferential intermediate sections 64. The same applies to the second regions 76 with low hardness that are provided on the axial end sections, the hollow section 66, and the clamping target section 70.The screw holes 68 are provided in the second region 76 with low hardness, which extends in a depth direction from the axial end sections of the rotating body 12.

[0041] The hardness of the first regions 74 with low hardness is lower than the hardness of the regions 72 with high hardness and is higher than the hardness of the second regions 76 with low hardness. Each of the first regions 74 with low hardness has a linear shape extending in the axial direction X of the body of revolution 12.

[0042] The high-hardness regions 72 and the first low-hardness regions 74 are constructed from surface treatment regions 78 provided on a treatment target material by performing a surface treatment on the treatment target material. In the present embodiment, laser heating is used as the surface treatment. The high-hardness regions 72 and the first low-hardness regions 74 can be considered regions that are made harder than a base material region by surface heat treatment with respect to the treatment target material. The high-hardness regions 72 are provided by partial quenching, which is carried out by means of laser heating, i.e., laser quenching. Therefore, the main phase of the microstructure of the high-hardness region 72 is, for example, a quenched structure, such as α-martensite.Furthermore, the first low-hardness regions 74 are provided by partial annealing, which is carried out by means of laser heating. Therefore, the main phase of the microstructure of the first low-hardness region 74 is, for example, an annealed structure, such as troostite and sorbite. The first low-hardness region 74 is a region referred to as a soft zone and is provided on a section that is re-irradiated with laser light, which will be described later.

[0043] On the other hand, the second regions 76, which have low hardness, are composed of base material regions 80, the hardness of which is equal to that of the base material of the target material undergoing surface treatment. The main phase of the microstructure of the second region 76, which has low hardness, is a standard structure, such as a two-phase structure of ferrite and pearlite.

[0044] Fig. Figure 4 shows a relationship between depth of a surface in region 72 with high hardness and Vickers hardness. Fig. Figure 4 shows Vickers hardness values ​​plotted on multiple sections arranged in a depth direction from the surface of the high-hardness region 72. The depth direction here means a direction perpendicular to the surface of the high-hardness region 72. Each of the numbers near measurement points in the graph shows the amount of change in Vickers hardness from a neighboring measurement point located on a surface face (hereinafter referred to as the amount of hardness change). The amounts of hardness change are the amounts of change in Vickers hardness measured at 0.1 mm intervals in a depth direction of Pa.

[0045] The high-hardness region 72 provided by laser quenching consists of a surface layer region 82 and a hardness transition region 84. The surface layer region 82 extends from the surface of the high-hardness region 72, and the hardness transition region 84 extends from the surface layer region 82 to the base material region 80 (the second low-hardness region 76). The hardness transition region 84 is a region where the hardness decreases sharply in the depth direction. The hardness transition region 84 extends in the depth direction, beginning with a section where the amount of hardness change transitions from a value equal to or greater than zero to a negative value, and includes a section where the amount of hardness change is at least -60 or less. For example, the length of the hardness transition region 84 in the depth direction is 0.3 mm to 0.8 mm.The hardness change amounts are the amounts of change with respect to Vickers hardness, measured at intervals of 0.1 mm in the depth direction.

[0046] Surface layer region 82 is a region where the hardness does not decrease as rapidly as in hardness transition region 84. Surface layer region 82 must contain a section where the amount of hardness change is equal to or greater than zero. Furthermore, even if the value of the amount of hardness change is negative, surface layer region 82 is a region where the amount of hardness change is at least -60. Additionally, surface layer region 82 is also a region where the Vickers hardness does not increase or decrease significantly. For example, due to the relationship described above, in surface layer region 82, the difference between the maximum and minimum values ​​of the Vickers hardness is equal to or less than 100, and the amounts of hardness change fall within a range from a value greater than -60 to a value equal to or less than +60.

[0047] Base material region 80 extends in depth from hardness transition region 84, beginning at a point where the amount of hardness change transitions from a negative value to a value equal to or greater than zero. In base material region 80, the hardness does not increase or decrease significantly in the depth direction. For example, due to the relationship described above, in base material region 80, the difference between the maximum and minimum Vickers hardness values ​​is equal to or less than 50, and the amounts of hardness change fall within a range from a value equal to or greater than -50 to a value equal to or less than +50.

[0048] The description is given with reference to Fig. 3B and Fig. 3C. Directions from the rotational centerline CL1 of the crankshaft 14 to the axial centers CL3 of the eccentric sections 34A and 34B are designated as maximum eccentric directions Pa1, and directions from the rotational centerline CL1 that are opposite to the maximum eccentric directions Pa1 are designated as antimaximal eccentric directions Pa2. Axial centers CL3 of the eccentric sections 34A and 34B are the geometric centers (centroids) of shapes formed by the outer circumferential surfaces of the eccentric sections 34A and 34B in a section perpendicular to the axial direction X. Lines extending in the maximum eccentric directions Pa1 from the axial centers CL3 of the eccentric sections 34A and 34B are called first reference lines La1, and lines extending in the counter-maximal eccentric directions Pa2 from the axial centers CL3 are called second reference lines La2.

[0049] In each of the rolling sections 40A and 40B of the eccentric sections 34A and 34B, a circumferential range of ±90 degrees from the first reference line La1 is designated as a high-load region Sa1, and a circumferential range of ±90 degrees from the second reference line La2 is designated as a low-load region Sa2. The maximum load is applied to the rolling sections 40A and 40B in the high-load regions Sa1, and almost no load is applied to the rolling sections 40A and 40B in the low-load regions Sa2. The low-load regions Sa2 can be considered as areas that are part of the total circumferential ranges of the rolling sections 40A and 40B and in which the load on the rolling sections 40A and 40B is low. In each low-load region Sa2, a particularly low load is exerted on a region Sa3 of ±30 degrees from the second reference line La2.

[0050] The first low-hardness regions 74 of rolling sections 40A and 40B are located within the low-load areas Sa2. All of the first low-hardness regions 74 of rolling sections 40A and 40B are located within the low-load areas Sa2. The first low-hardness regions 74 of rolling sections 40A and 40B are located within areas Sa3 of the low-load areas Sa2. The high-hardness regions 72 extend across the entire high-load areas Sa1 and sections of the low-load areas Sa2 that do not contain the first low-hardness regions 74. The first low-hardness regions 74 of the multiple rolling sections 40A and 40B are located in the low-load areas Sa2 corresponding to the respective rolling sections 40A and 40B.

[0051] The circumferential positions of the first low-hardness regions 74 of the sealing sections 60A and 60B are aligned with the circumferential positions of the first low-hardness regions 74 of the rolling sections 40A and 40B. This is referred to as a position condition A. In the case of the eccentrically oscillating type speed reducer, a circumferential position with respect to the sealing sections 60A and 60B is a position in a circumferential direction along a circle around the centerline of rotation CL1 of the rotating body 12. Furthermore, a circumferential position with respect to the rolling sections 40A and 40B is a position in a circumferential direction along circles around the axial centers CL3 of the eccentric sections 34A and 34B, which are provided with the rolling sections 40A and 40B.This means that circumferential areas in which the first regions 74 with low hardness of the sealing sections 60A and 60B are present as seen from the rotational center line CL1 of the rotating body 12, and circumferential areas in which the first regions 74 with low hardness of the rolling sections 40A and 40B are present as seen from the axial centers CL3 of the eccentric sections 34A and 34B, are aligned with each other. The term “aligned” here also means a case in which the circumferential positions of the first low-hardness regions 74 of the sealing sections 60A and 60B and the circumferential positions of the first low-hardness regions 74 of the rolling sections 40A and 40B are essentially the same, in addition to a case in which the circumferential positions of the first low-hardness regions 74 of the sealing sections 60A and 60B and the circumferential positions of the first low-hardness regions 74 of the rolling sections 40A and 40B are the same.This means that the term "aligned" does not only mean a case where the perimeter positions (phases) of the areas 74 completely coincide with each other, but also a case where the areas 74 partially coincide with each other.

[0052] In a case where several eccentric sections 34A and 34B are present, the position condition A only needs to be met between the rolling sections 40A and 40B of any one of the eccentric sections 34A and 34B and the sealing sections 60A and 60B. In the present embodiment, the position condition A is met between the first rolling section 40A of the first eccentric section 34A and the drive-side sealing section 60A, and between the second rolling section 40B of the second eccentric section 34B and the counter-drive-side sealing section 60B.In particular, the circumferential position of the first low-hardness region 74 of the first rolling section 40A and the circumferential position of the first low-hardness region 74 of the drive-side sealing section 60A are identical, and the circumferential position of the first low-hardness region 74 of the second rolling section 40B and the circumferential position of the first low-hardness region 74 of the counter-drive-side sealing section 60B are identical. Furthermore, the positional condition A can be satisfied between one of the multiple eccentric sections 34A and 34B and both of the multiple sealing sections 60A and 60B.

[0053] A manufacturing process for obtaining the revolved body 12 described above is described. The description is made with reference to Fig. 5. First, a manufacturing process is described using a reference example. In this process, a roughing step S10 is performed to form the outer shape of the turned body 12 by machining the material of the turned body 12, such as cutting. This is followed by a heat treatment step S12, in which a surface heat treatment is carried out by quenching the entire turned body 12 through carburizing and quenching or similar processes. After heat treatment step S12, a finishing step S14 is performed, involving grinding the surface of a quenched section of the turned body 12 to remove heat stress. Finally, after heat treatment step S12, a drilling step S16 is performed to create the screw holes 68 in the turned body 12.

[0054] Here, heat treatment step S12 is primarily performed to ensure the hardness of a section (sealing sections 60A and 60B and rolling sections 40A and 40B) that requires high hardness. When the entire rotary body 12 is quenched in heat treatment step S12, the hardness of a section other than the one requiring high hardness is also increased. Therefore, in finishing step S14 and hole drilling step S16, machining targeted at a section requiring high hardness must be performed on a section (bearing assembly sections 62A and 62B, axial end sections, hollow section 66, and the like) that does not initially require high hardness.

[0055] The manufacturing process of the present embodiment, which is a countermeasure to the problem described above, is described. The description is made with reference to Fig. 6. In the manufacturing process, a rough machining step S20 is performed to form the outer shape of the turned body 12, as in the reference example. After rough machining step S20, a pre-machining step is performed before a heat treatment step S26 is carried out. The pre-machining step includes a finishing step S22 of grinding an outer surface section of the turned body 12, wherein the finishing step S22 is directed at a section other than the section to be subjected to heat treatment. The section to be subjected to heat treatment refers, for example, to the outer circumferential intermediate sections 64, the hollow section 66, and the clamping target section 70 of the turned body 12. In addition, the pre-machining step includes a drilling step S24 to form the screw holes 68 in the axial end section of the turned body 12, as described above.

[0056] Next, heat treatment step S26, involving the partial quenching of a section of the rotating body 12, is performed for the section to be heat treated. As described above, the section to be heat treated refers to the sealing sections 60A and 60B and the rolling sections 40A and 40B of the rotating body 12. Details will be described later.

[0057] Following heat treatment step S26, a finishing step S28 is performed, involving grinding a surface of the rotating body 12. Finishing step S28 targets a section (sealing sections 60A and 60B and rolling sections 40A and 40B of the rotating body 12) that underwent heat treatment in heat treatment step S26. The finishing steps S22 and S28 described above are performed by grinding the surface of the rotating body 12 to achieve a target surface roughness.

[0058] A heat treatment process used in the heat treatment step S26 described above is described. The description is made with reference to Fig. 7A to 7D. The heat treatment process is carried out by performing a surface heat treatment using a heat treatment device 90 and laser light 92. The heat treatment device 90 includes a head 94 that irradiates the rotating body 12 with the laser light 92, and a clamping device (not shown) that can move the rotating body 12 in a clamped position.

[0059] The heat treatment process comprises a first step of performing heat treatment on the rolling sections 40A and 40B, and a second step of performing heat treatment on the sealing sections 60A and 60B. The order in which the first and second steps are performed is not particularly restricted. Furthermore, the order in which the first step is performed with respect to each of the multiple rolling sections 40A and 40B, and the second step with respect to each of the multiple sealing sections 60A and 60B, is also not particularly restricted. For example, the steps can be performed in this order: the first step for the first rolling section 40A, the second step for the inlet-side sealing section 60A, the first step for the second rolling section 40B, and the second step for the outlet-side sealing section 60B.

[0060] In both the first and second steps, the clamping target section 70 (see Fig. 2) of the rotating body 12 is clamped by the clamping device. At this point, the rotating body 12 is clamped by applying a radially inwardly directed compressive force to the clamping target section 70 of the rotating body 12.

[0061] The first and second steps are performed while maintaining the same clamping condition.

[0062] In both the first and second steps, heat treatment is performed on the rotating body 12 by irradiating it with laser light 92 from the head 94. At this point, the heat treatment is carried out by changing the irradiation position of the laser light 92 in a circumferential direction. The rotating body 12 can be rotated by the clamping device, or the head 94 can be rotated around the rotating body 12 to achieve this. In the first step, the rotating body 12 or the head 94 is moved to rotate around the axial centers CL3 of the eccentric sections 34A and 34B, which are provided with the rolling sections 40A and 40B (see Fig. 7A). In the second step, the rotating body 12 or the head 94 is moved to rotate around the rotation centerline CL1 of the rotating body 12 (see Fig. 7C). Accordingly, irradiation with the laser light can be carried out with a constant distance between the irradiation position of the laser light 92 and the head 94.

[0063] After the rolling sections 40A and 40B were quenched in the first step over their entire circumferential areas by changing the irradiation position of the laser light 92 in the circumferential direction, a section of the areas irradiated with the laser light 92 is irradiated again. A series of operations, as described above, is carried out in one process. The heat treatment is performed in one process by moving the irradiation position of the laser light 92 relative to the rotating body 12 in the circumferential direction of the eccentric sections 34A and 34B (circumferential direction along circles around the axial centers CL3 of the eccentric sections 34A and 34B). Sections that are irradiated again with the laser light at this time form linear shapes and are set within the low-load areas Sa2 of the rolling sections 40A and 40B described above.

[0064] In the second step, after the sealing sections 60A and 60B have been quenched over the entire circumferential area of ​​the rotating body 12 by changing the irradiation position of the laser light in the circumferential direction, a section of the areas irradiated with the laser light is irradiated again. Sections that are irradiated again with the laser light at this time are adjusted to form linear shapes.

[0065] In both the first and second steps, the first regions 74 of low hardness are treated by tempering on the sections that are irradiated with laser light again. Conversely, on the irradiated sections, with the exception of those that are irradiated with laser light again, the regions 72 of high hardness are treated by laser quenching.

[0066] The circumferential positions of sections of the rolling sections 40A and 40B, which are irradiated with laser light again in the first step, and the circumferential positions of sections of the sealing sections 60A and 60B, which are irradiated with laser light again in the second step, are aligned with each other. This is referred to as position condition B. Here, the definitions of a circumferential position with respect to the rolling sections 40A and 40B and a circumferential position with respect to the sealing sections 60A and 60B are the same as described above. Furthermore, the definition of "aligned" is the same as described above. Accordingly, position condition A described above can be satisfied between the first low-hardness regions 74 of the rolling sections 40A and 40B and the first low-hardness regions 74 of the sealing sections 60A and 60B.As with position condition A, in a case where several of the eccentric sections 34A and 34B are present, position condition B must only be fulfilled between the rolling sections 40A and 40B of one of the eccentric sections 34A and 34B and the sealing sections 60A and 60B. In the present embodiment, position condition B is fulfilled between the first rolling section 40A of the first eccentric section 34A and the inlet-side sealing section 60A, and between the second rolling section 40B of the second eccentric section 34B and the opposite-inlet sealing section 60B.

[0067] The advantageous effects of this are described. The description is based on a workflow from the end of a preceding step, which is one of the first and second steps, to the start of a subsequent step, which is the other of the first and second steps. A position where the head 94 must be positioned at the time the preceding step ends is called the end position for the preceding step, and a position where the head 94 must be positioned at the time the subsequent step starts is called the start position for the subsequent step. It is necessary to change the relative positions of the head 94 and the rotating body 12 from the end position for the preceding step to the start position for the subsequent step between the end of the preceding step and the start of the subsequent step.Here, the final position for the previous step is radially outside a section that is irradiated with laser light again in the previous step (see, for example, ). Fig. 7B). Furthermore, the starting position for the subsequent step is radially outside a section that will be irradiated with laser light again in the subsequent step (see, for example, Figure 7B). Fig. 7D). As described above, in a case where the circumferential position of a section that is irradiated with laser light again in the first step and the circumferential position of a section that is irradiated with laser light again in the second step are aligned, it is possible to suppress the amount of relative movement of the head 94 and the rotating body 12 in the circumferential position during a period between the preceding step and the subsequent step, compared to a case where the circumferential positions are significantly offset from each other. Accordingly, the working time for the heat treatment step can be reduced, and a reduction in manufacturing costs can be achieved with an improvement in manufacturing efficiency.

[0068] With regard to such an effect, the width Wa of lines formed by the first low-hardness regions 74 of the rolling sections 40A and 40B and by the first low-hardness regions 74 of the sealing sections 60A and 60B is preferably equal to or less than 5 mm and further preferably equal to or less than 2 mm. Furthermore, the lower limit of the width Wa is preferably equal to or greater than 1 mm. It is preferred that the width Wb of lines formed by the re-irradiated sections also meets the same conditions.

[0069] The effect of the speed reducer 10 described above is described.

[0070] (A) The sealing sections 60A and 60B of the rotary body 12 are laser-quenched to high-hardness regions 72, and the outer surface sections of the rotary body 12 are laser-quenched to low-hardness regions 76. Therefore, it is not necessary to perform finishing work on the low-hardness regions 76 to eliminate heat stress after heat treatment by laser quenching. Accordingly, the area of ​​finishing work targeted on the high-hardness regions 72 can be reduced compared to a case where the entire rotary body 12 is quenched. This can result in a reduction in manufacturing costs.

[0071] (B) The second regions 76 with low hardness of the rotating body 12 are provided with the outer circumferential intermediate sections 64 between the rolling sections 40A and 40B and the sealing sections 60A and 60B. Therefore, it is possible to eliminate the need for the outer circumferential intermediate sections 64, which is necessary to eliminate heat stress in the regions 72 with high hardness. Accordingly, a reduction in manufacturing costs can be achieved.

[0072] (C) The circumferential positions of the first low-hardness regions 74 of the sealing sections 60A and 60B are aligned with the circumferential positions of the first low-hardness regions 74 of the rolling sections 40A and 40B. As described above, it is possible to suppress the amount of relative movement of the head 94 and the rotating body 12 in the circumferential position during a period between the preceding step and the subsequent step. Accordingly, a reduction in manufacturing costs can be achieved.

[0073] (D) The bearing arrangement sections 62A and 62B of the outer circumferential intermediate sections 64 are located in the second regions 76 with low hardness. Therefore, it is possible to eliminate the need for the finishing operations required to eliminate heat stress, which are necessary for the regions 72 with high hardness, for the bearing arrangement sections 62A and 62B.

[0074] (E) In a case where the drive bearings 30A and 30B are mounted on the rotating body 12, the drive bearings 30A and 30B are moved from their outer sides in the axial direction of the rotating body 12 to the bearing arrangement sections 62A and 62B, so that the drive bearings 30A and 30B are positioned on the bearing arrangement sections 62A and 62B. In a case where the difference between the radius of the sealing sections 60A and 60B and the radius of the bearing arrangement sections 62A and 62B is equal to or less than 2 mm, scratches may be generated here when the drive bearings 30A and 30B come into contact with the sealing sections 60A and 60B when the drive bearings 30A and 30B are moved as described above. In this context, the sealing sections 60A and 60B of the rotating body 12 according to the present embodiment are provided with regions 72 of high hardness.Therefore, it is possible to suppress the formation of scratches on the sealing sections 60A and 60B caused by the installation of the drive bearings 30A and 30B. The point described above is particularly advantageous insofar as it makes it possible to suppress the formation of scratches and at the same time to selectively reduce the area of ​​finishing to the regions 72 with high hardness.

[0075] (F) The hollow section 66 is located in the second region 76 with low hardness. Therefore, it is possible to eliminate the need for the finishing work required to remove heat stress, which is necessary for the regions 72 with high hardness, for the hollow section 66.

[0076] (G) The screw holes 68 are located in the second region 76 with low hardness. Therefore, it is possible to perform the drilling of the screw holes 68 in the second region 76 with low hardness instead of in the regions 72 with high hardness. Thus, compared to a case where the entire rotating body 12 is quenched, sections that are easy to machine (second region 76 with low hardness) can be designated as the sections for which the drilling for the screw holes 68 needs to be carried out. (Second embodiment)

[0077] The description is given with reference to Fig. 8. The speed reducer 10 of the present embodiment is a speed reducer 10 of the bending engagement type, which includes a shaft generator shaft 100, which is the rotating body 12. In addition, the speed reducer 10 of the bending engagement type includes a flexible gear 102, which is bent and deformed by means of the shaft generator shaft 100 and the gear bearing 18 arranged between the shaft generator shaft 100 and the flexible gear 102. Furthermore, the speed reducer 10 includes the outer gear 20 and the meshing inner gears 22A and 22B, the housing 24, which is arranged near an outer circumferential side of the flexible gear 102, and the supports 26A and 26B, which are provided on lateral sides with respect to the outer gear 20 in the axial direction, wherein the outer gear 20 or the inner gears 22A and 22B serve as the flexible gear 102.Furthermore, the speed reducer 10 includes the oil seals 28A and 28B, which are arranged between the supports 26A and 26B and the generator shaft 100, and the drive bearings 30A and 30B, which are arranged between the supports 26A and 26B and the generator shaft 100. In the speed reducer 10 of the present embodiment, the external gear 20 is the flexible gear 102. Furthermore, the speed reducer 10 of the present embodiment is a tubular speed reducer of the bending-engagement type, in which several internal gears 22A and 22B are used. Hereinafter, a direction along the axis of rotation CL1 of the rotating body 12 (generator shaft 100) is referred to as the axial direction X.

[0078] The shaft generator 100 can be rotated by means of a torque transmitted by a drive device (not shown). The shaft generator 100 has sufficient stiffness to cause the flexible gear 102 to bend and deform as it rotates. The shaft generator 100 incorporates a shaft generator 104, which bends and deforms the flexible gear 102 and the shaft sections 106 provided on both sides in the axial direction with respect to the shaft generator 104. The outer circumference of the shaft generator 104 is oval, as seen in a cross-section perpendicular to the axial direction of the shaft generator 100. The term "oval shape" here is not limited to a geometrically exact oval shape, but also means an approximately oval shape. The outer circumference of each shaft section 106 is circular, as seen in a cross-section perpendicular to the axial direction of the shaft generator 100.

[0079] The flexible gear 102 is a tubular element that exhibits flexibility. The flexible gear 102 is rotatably mounted on the shaft generator 104 via the gear bearings 18.

[0080] The gear bearings 18 of the present embodiment each correspond to the multiple internal gears 22A and 22B and are arranged separately within the respective internal gears 22A and 22B. The gear bearings 18 contain the multiple rolling elements 36, which are arranged between the flexible gear 102 and the shaft generator 104 of the shaft generator shaft 100, the retainers 38, which maintain the relative positions of the multiple rolling elements 36, and flexible outer rings 108, which are arranged near the outer circumferential faces of the multiple rolling elements 36. The rolling elements 36 of the present embodiment are rollers. The gear bearings 18 do not contain dedicated inner rings. Instead, the shaft generator 104 also serves as an inner ring, and the shaft generator shaft 100 contains rolling sections 40C on which the rolling elements 36 roll. The rolling sections 40C are constructed from outer circumferential sections of the shaft generator 104.As with the flexible gear 102, the outer rings 108 are flexible, tubular elements and are bent and deformed by the shaft generator 104.

[0081] The internal gears 22A and 22B are arranged near the outer circumferential side of the external gear 20. The internal gears 22A and 22B are stiff enough that they do not deform after rotation of the generator shaft 100. In the present embodiment, the internal gears 22A and 22B comprise a drive-side internal gear 22A, located on the drive side, and a counter-drive-side internal gear 22B, located on the counter-drive side.

[0082] The housing 24 accommodates other components of the speed reducer 10, such as the flexible gear 102. The housing 24 contains a first housing element 110, which also serves as the drive-side internal gear 22A, and a second housing element 112, which is located close to an outer circumferential side of the counter-drive-side internal gear 22B.

[0083] The carriers 26A and 26B comprise the drive-side carrier 26A, which is arranged axially on the drive side with respect to the external gear 20, and the counter-drive-side carrier 26B, which is arranged axially on the counter-drive side. The drive-side carrier 26A is integrated with the drive-side internal gear 22A. The counter-drive-side carrier 26B is integrated with the counter-drive-side internal gear 22B.

[0084] As in the first embodiment, the oil seals 28A and 28B comprise the drive-side oil seal 28A and the counter-drive-side oil seal 28B. The drive-side oil seal 28A is arranged between the drive-side support 26A and the rotating body 12 (shaft section 106 of the generator shaft 100). The counter-drive-side oil seal 28B is arranged between the counter-drive-side support 26B and the rotating body 12 (shaft section 106 of the generator shaft 100). The configurations of the oil seals 28A and 28B are the same as in the first embodiment.

[0085] As in the first embodiment, the drive bearings 30A and 30B comprise the drive-side drive bearing 30A and the counter-drive-side drive bearing 30B. The drive-side drive bearing 30A is arranged between the drive-side support 26A and the rotating body 12 (shaft section 106 of the generator shaft 100). The counter-drive-side drive bearing 30B is arranged between the counter-drive-side support 26B and the rotating body 12 (shaft section 106 of the generator shaft 100). The configurations of the drive bearings 30A and 30B are the same as in the first embodiment.

[0086] The output element rotates synchronously with an axial rotational component of the external gear 20 or the internal gears 22A and 22B (external gear 20 in the present embodiment) to transmit the axial rotational component to the driven device. One of the output element and the fixed element is the input-side support 26B, and the other of the output element and the fixed element is the housing 24. In a case where the input-side support 26B serves as the output element, the external gear 20 rotates together with the input-side internal gear 22B, and in a case where the housing 24 serves as the output element, the external gear 20 rotates together with the input-side internal gear 22A.

[0087] The operation of the speed reducer 10 described above is described. When torque is transmitted from the drive device to the shaft generator shaft 100, the shaft generator shaft 100 rotates. During this rotation, the flexible gear 102 is bent and deformed into an oval shape that corresponds to the shape of the shaft generator 104 of the shaft generator shaft 100. Consequently, the positions where the outer gear 20 and the internal gears 22 mesh are sequentially displaced in a circumferential direction. As a result, the outer gear 20 or the internal gears 22A and 22B (outer gear 20 in the present embodiment) rotate together with the output element.Rotation of the shaft generator shaft 100 is output to the driven device via the output element after it has been subjected to a speed reduction with a reduction ratio corresponding to the outer gear 20 and the inner gears 22A and 22B.

[0088] The description is given with reference to Fig. 9. The rotating body 12, which is the shaft generator shaft 100, contains, in addition to the rolling sections 40C described above, the sealing sections 60A and 60B, which come into contact with the oil seals 28A and 28B, and the bearing arrangement sections 62A and 62B, on which the drive bearings 30A and 30B are arranged, as in the first embodiment.

[0089] As in the first embodiment, the sealing sections 60A and 60B comprise the drive-side sealing section 60A and the counter-drive-side sealing section 60B. As in the first embodiment, the bearing arrangement sections 62A and 62B comprise the drive-side bearing arrangement section 62A and the counter-drive-side bearing arrangement section 62B. The bearing arrangement sections 62A and 62B are provided on the outer circumferential intermediate sections 64, which are located between the rolling sections 40C and the sealing sections 60A and 60B.

[0090] As in the first embodiment, the difference between the radius of the sealing sections 60A and 60B, which are arranged in the axial direction outside the bearing arrangement sections 62A and 62B, and the radius of the bearing arrangement sections 62A and 62B is equal to or less than 2 mm.

[0091] Furthermore, the rotating body 12 contains the hollow section 66 and the screw holes 68 as in the first embodiment. In contrast to the first embodiment, the screw holes 68 are arranged in positions where they overlap with the drive-side sealing section 60A in the radial direction.

[0092] The description is given with reference to Fig. 9 and Fig. 10A to 10C. In the drawings, regions 72 with high hardness are shown double hatched, the first regions 74 with low hardness are shown single hatched, and the second regions 76 with low hardness are shown unhatched.

[0093] As in the first embodiment, outer surface sections of the rotating body 12 are provided with regions 72 of high hardness and regions 74 and 76 of low hardness. As in the first embodiment, the regions 72 of high hardness are located on the sealing sections 60A and 60B and the rolling sections 40C as the outer surface sections of the rotating body 12. As in the first embodiment, the regions 74 and 76 of low hardness comprise the first regions 74 of low hardness, which are located on the sealing sections 60A and 60B and on the rolling sections 40C, and the second regions 76 of low hardness, which are located on sections other than the sealing sections 60A and 60B and the rolling sections 40C.

[0094] The way in which the first regions 74 with low hardness of the sealing sections 60A and 60B and the rolling sections 40C are provided is the same as in the first embodiment. The second regions 76 with low hardness are provided, for example, on the outer circumferential intermediate sections 64, the hollow section 66, and the axial end sections of the rotating body 12, respectively.

[0095] The hardness of regions 72 with high hardness, the first regions 74 with low hardness, and the second regions 76 with low hardness, and the manner in which regions 72 with high hardness, the first regions 74 with low hardness, and the second regions 76 with low hardness are provided, are the same as in the first embodiment. For example, regions 72 with high hardness are provided by laser quenching.

[0096] The description is given with reference to Fig. 10B. A line extending along a principal axis direction Da of the shaft generator 104 from the rotational centerline CL1 of the shaft generator shaft 100 is called a first reference line Lc1, and a line extending along a minor axis direction Db from the rotational centerline CL1 is called a second reference line Lc2. The principal axis direction Da signifies a direction along a principal axis of an oval shape formed by a cross-sectional shape of the shaft generator 104. The minor axis direction Db signifies a direction along a minor axis of the oval shape formed by a cross-sectional shape of the shaft generator 104. The cross-sectional shape of the shaft generator 104 here means a shape as seen in a cross-section perpendicular to the rotational centerline CL1.

[0097] A region of ±45 degrees from the first reference line Lc1 within a region around the rotational centerline CL1 of the shaft generator 104 is designated as a high-load region Sb1, and a region of ±45 degrees from the second reference line Lc2 within the region around the rotational centerline CL1 of the shaft generator 104 is designated as a low-load region Sb2. With respect to the shaft generator 104, the maximum load is exerted on the high-load region Sb1, and virtually no load is exerted on the low-load region Sb2. The low-load region can be considered a region in which the load on the rolling section 40C is low across its entire circumference.

[0098] The first low-hardness region 74 of rolling section 40C is located within the low-load area Sb2. The entire first low-hardness region 74 of rolling section 40C is positioned within the low-load area Sb2. The high-hardness region 72 extends across the entire high-load area Sb1 and a portion of the low-load area Sb2 that excludes the first low-hardness region 74.

[0099] The circumferential positions of the first low-hardness regions 74 of the sealing sections 60A and 60B are aligned with the circumferential positions of the first low-hardness regions 74 of the rolling sections 40C. In the bending-engagement type speed reducer 10, a circumferential position relating to the sealing sections 60A and 60B and the rolling sections 40C is a position in a circumferential direction along a circle around the centerline of rotation CL1 of the rotating body 12. The definition of "aligned" is the same as in the first embodiment.

[0100] A manufacturing process for obtaining the rotary body 12 (shaft generator shaft 100) described above is the same as in the first embodiment. That is, the shaft generator shaft 100 can be obtained by performing the roughing step S20, the pre-machining step (finishing step S22 and hole drilling step S24), the heat treatment step S26, and the finishing step S28 in that order.

[0101] The heat treatment process used in the heat treatment step S26 described above, which is performed on the rotating body 12 (shaft generator shaft 100), is also the same as that used in the first embodiment. That is, the heat treatment process includes the first step for performing heat treatment on the rolling sections 40C and a second step for performing heat treatment on the sealing sections 60A and 60B.

[0102] Both the first step and the second step can be performed in a state in which any section of the rotating body 12 is clamped by the clamping device.

[0103] As in the first embodiment, in the first step, after the rolling sections 40C have been quenched over the entire circumferential area of ​​the wave generator shaft 100 by changing the irradiation position of laser light in the circumferential direction, a section of the areas irradiated with the laser light is irradiated again with the laser light.

[0104] As in the first embodiment, in the second step, after the sealing sections 60A and 60B have been quenched over the entire circumferential area of ​​the rotating body 12 by changing the irradiation position of the laser light in the circumferential direction, a section of areas irradiated with the laser light is irradiated again with the laser light.

[0105] As in the first embodiment, the circumferential positions of sections of the rolling sections 40C, which are irradiated with laser light again in the first step, and the circumferential positions of sections of the sealing sections 60A and 60B, which are irradiated with laser light again in the second step, are aligned with each other. Accordingly, as in the first embodiment, the working time for the heat treatment step can be reduced and a reduction in manufacturing costs can be achieved with an improvement in manufacturing efficiency.

[0106] The speed reducer 10 in the present embodiment also contains the components described in (A) to (G) above (not shown), and thus the corresponding effects can be achieved.

[0107] Other modified versions of each component will now be described.

[0108] The eccentrically oscillating speed reducer 10 can be a distribution-type speed reducer in which several crankshafts 14 are arranged at positions offset radially from the central axis of the internal gear 22. The eccentrically oscillating speed reducer 10 can also be an internal gear oscillating speed reducer in which the internal gear 22 serves as the oscillating gear 16.

[0109] In the speed reducer 10 of the bending-engage type, the internal gear 22 can be the flexible gear 102. Furthermore, the type of speed reducer 10 of the bending-engage type is not particularly restricted. For example, a pot-type or cylinder-type speed reducer of the bending-engage type can also be used by providing an internal gear.

[0110] It is possible that the high-hardness regions 72 on the rolling sections 40A, 40B, and 40C of the rotating body 12 are not provided in order to achieve the effect with respect to (A). Furthermore, it is possible that the first low-hardness regions 74 on the sealing sections 60A and 60B of the rotating body 12 are not provided. Additionally, the circumferential positions of the first low-hardness regions 74 of the rolling sections 40A, 40B, and 40C of the rotating body 12 and the circumferential positions of the first low-hardness regions 74 of the sealing sections 60A and 60B of the rotating body 12 may not be aligned with each other.

[0111] It is possible that the first regions 74 with low hardness on the rolling sections 40A, 40B, and 40C and the sealing sections 60A and 60B of the rotating body 12 are not provided in order to achieve the effect with respect to (B). Furthermore, the regions 72 with high hardness of the rotating body 12 may be provided by partial quenching other than laser quenching. Examples of partial quenching include quenching performed inside a heating furnace in a state where a section other than the one to be heat-treated is masked by anti-carburization machining or the like, in addition to quenching, such as induction quenching, performed outside a heating furnace. Additionally, it is possible that the bearing assembly sections 62A and 62B on the outer circumferential intermediate sections 64 of the rotating body 12 are not provided in order to achieve the effect with respect to (B).

[0112] The outer circumferential intermediate sections 64 of the rotating body 12 can be provided with the first regions 74 of low hardness and the regions 72 of high hardness instead of the second regions 76 of low hardness to achieve the effect with respect to (C). Furthermore, the regions 72 of high hardness of the rotating body 12 can be provided by a partial quenching process other than laser quenching. Additionally, the first regions 74 of low hardness of the rolling sections 40A and 40B and the sealing sections 60A and 60B need not form linear shapes to achieve the effect with respect to (C). The first regions 74 of low hardness can, for example, form point-like shapes or the like.

[0113] A difference between the radius of the sealing sections 60A and 60B and the radius of the bearing arrangement sections 62A and 62B may exceed 2 mm.

[0114] The high-hardness regions 72 can be located in sections other than the sealing sections 60A and 60B and the rolling sections 40A, 40B, and 40C. Furthermore, at least one of the hollow sections 66 or the screw holes 68 can be located in the high-hardness region 72.

[0115] It is possible that in both the eccentrically oscillating speed reducer and the bending-engagement speed reducer, the rotating body 12 does not contain the hollow section 66 and the screw holes 68. Furthermore, in both speed reducers, the screw holes 68 may be located in positions where they overlap the sealing sections 60A and 60B in the radial direction.

[0116] At the in Fig.In the manufacturing process shown in Figure 6, the hole drilling step S24 can be performed after the heat treatment step S26 instead of before it. Furthermore, the finishing step S22, which targets a different section than the one to be heat-treated, can be performed after heat treatment step S26 instead of before it. In any case, it is possible to eliminate machining operations targeting a section with high hardness that are not required for a section (bearing assembly sections 62A and 62B, hollow section 66, axial end sections, or the like) that does not require high hardness.

[0117] The embodiments and modified embodiments described above are examples. The technical ideas obtained by abstracting the embodiments and modified embodiments should not be interpreted as being limited to the content of the embodiments and modified embodiments. Various design changes, such as modifying, adding, or omitting a component, may be made to the content of the embodiments and modified embodiments. In the embodiments described above, content that may be subject to such a design change is highlighted by the addition of the designation "Embodiment." However, design changes are also permissible for content without such a designation. Hatching in the cross-sections of the drawings is not intended to restrict the material of a hatched object. Brief description of the reference symbols 10 speed reducers 12 Rotating Bodies 14 Crankshaft 16 oscillating gear 28A, 28B Oil seal 30A, 30B Inbound Storage 34A, 34B Eccentric section 36 rolling elements 40A, 40B, 40C rolling section 60A, 60B Sealing section 62A, 62B Storage arrangement section 66 Hollow section 68 screw holes 72 Region with high hardness 74 first region with low hardness 76 second region with low hardness 100 shaft generator shaft 102 Flexible gear 104 Wave generator

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