WO2023071231A1 - 谐波齿轮装置、谐波齿轮装置的制造方法、机器人用关节装置和齿轮部件 - Google Patents

谐波齿轮装置、谐波齿轮装置的制造方法、机器人用关节装置和齿轮部件 Download PDF

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Publication number
WO2023071231A1
WO2023071231A1 PCT/CN2022/099475 CN2022099475W WO2023071231A1 WO 2023071231 A1 WO2023071231 A1 WO 2023071231A1 CN 2022099475 W CN2022099475 W CN 2022099475W WO 2023071231 A1 WO2023071231 A1 WO 2023071231A1
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WIPO (PCT)
Prior art keywords
gear
teeth
flexible external
external gear
harmonic
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PCT/CN2022/099475
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English (en)
French (fr)
Inventor
王刚
林文捷
峯岸清次
伊佐地毅
郭子铭
Original Assignee
美的集团股份有限公司
广东极亚精机科技有限公司
广东美的制冷设备有限公司
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Application filed by 美的集团股份有限公司, 广东极亚精机科技有限公司, 广东美的制冷设备有限公司 filed Critical 美的集团股份有限公司
Priority to EP22885137.4A priority Critical patent/EP4421350A1/en
Priority to CN202280069926.9A priority patent/CN118140074A/zh
Publication of WO2023071231A1 publication Critical patent/WO2023071231A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
    • B23P15/14—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass gear parts, e.g. gear wheels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/10—Programme-controlled manipulators characterised by positioning means for manipulator elements
    • B25J9/102—Gears specially adapted therefor, e.g. reduction gears
    • B25J9/1025—Harmonic drives
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H49/00—Other gearings
    • F16H49/001—Wave gearings, e.g. harmonic drive transmissions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23F—MAKING GEARS OR TOOTHED RACKS
    • B23F15/00—Methods or machines for making gear wheels of special kinds not covered by groups B23F7/00 - B23F13/00
    • B23F15/02—Making gear teeth on wheels of varying radius of operation, e.g. on elliptical wheels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H49/00—Other gearings
    • F16H49/001—Wave gearings, e.g. harmonic drive transmissions
    • F16H2049/003—Features of the flexsplines therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/02—Toothed members; Worms
    • F16H55/08—Profiling
    • F16H55/0833—Flexible toothed member, e.g. harmonic drive

Definitions

  • the present disclosure generally relates to a harmonic gear device, a manufacturing method of a harmonic gear device, a joint device for a robot, and a gear part, and more particularly, to a harmonic gear device including a rigid internal gear, a flexible external gear, and a wave generator, A method of manufacturing a harmonic gear device, a joint device for a robot, and a gear part.
  • Patent Document 1 discloses that the surface treatment of a flexible external gear in a harmonic gear device (flexural mesh gear device) is carried out by nitriding treatment.
  • the harmonic gear device has: a ring-shaped rigid internal gear; a cup-shaped flexible external gear arranged inside; and an elliptical wave generator embedded in the inside.
  • the flexible external gear includes a cylindrical body and external teeth formed on the outer peripheral surface of the body.
  • the flexible external gear is bent into an ellipse by the wave generator, and portions of the external teeth located at both ends of the ellipse in the major axis direction mesh with internal teeth formed on the inner peripheral surface of the rigid internal gear.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2001-59153
  • the external teeth located at both ends of the long-axis direction of the elliptical flexible external gear press the internal teeth of the rigid internal gear like wedges, whereby the external teeth and the internal teeth Mesh to get a rotary output. Therefore, the external teeth and the internal teeth rub against each other in a state where the external teeth are pushed against the internal teeth, particularly at the contact portion of the external teeth and the internal teeth. Therefore, at the contact part between the external teeth and the internal teeth, loss due to wear occurs, resulting in surface roughness, rust due to wear powder, and wave generator ( bearing) damage, etc., the power transmission efficiency of the harmonic gear unit may decrease.
  • the present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a harmonic gear device, a method of manufacturing a harmonic gear device, a joint device for a robot, and a gear member that are less prone to degradation in power transmission efficiency.
  • a harmonic gear device includes a rigid internal gear, a flexible external gear, and a wave generator.
  • the rigid internal gear is an annular member having internal teeth.
  • the flexible external gear is an annular member having external teeth and arranged inside the rigid internal gear.
  • the wave generator has a non-circular cam that is rotationally driven about a rotating shaft, and a bearing mounted on the outer side of the cam. The wave generator is arranged inside the flexible external gear and makes the flexible external gear deflect.
  • the harmonic gear device deforms the flexible external gear as the cam rotates, and a part of the external teeth meshes with a part of the internal teeth, so that the flexible external gear conforms to the
  • the rigid internal gear rotates relative to the rigid internal gear due to the difference in the number of teeth of the rigid internal gear.
  • At least one of the outer teeth and the inner teeth includes a rolling surface.
  • a method of manufacturing a harmonic gear device includes: a step of preparing a first base material to be a base of the rigid internal gear; and a step of preparing a second base material to be a base of the flexible external gear; The process of forming the internal teeth on the first base material; the process of forming the external teeth on the second base material; and forming the external teeth on at least one of the external teeth and the internal teeth by plastic working Describe the process of rolling the surface.
  • a joint device for a robot includes: the harmonic gear unit; a first member fixed to the rigid internal gear; and a second member fixed to the flexible external gear.
  • a gear member according to one aspect of the present disclosure is used as the rigid internal gear or the flexible external gear of the harmonic gear device.
  • FIG. 1A is a cross-sectional view showing a schematic configuration of a harmonic gear device according to an embodiment.
  • FIG. 1B is an enlarged view of area Z1 of FIG. 1A .
  • Fig. 2A is a schematic diagram of the above-mentioned harmonic gear device viewed from the input side of the rotary shaft.
  • FIG. 2B is an enlarged view of area Z1 of FIG. 2A .
  • FIG. 3A is a schematic exploded perspective view of the above harmonic gear device viewed from the output side of the rotary shaft.
  • Fig. 3B is a schematic exploded perspective view of the above-mentioned harmonic gear device viewed from the input side of the rotary shaft.
  • FIG. 4 is a cross-sectional view showing a schematic configuration of an actuator including the above-mentioned harmonic gear device.
  • FIG. 5 is an enlarged schematic cross-sectional view of a main part of a range corresponding to FIG. 1B .
  • 6A is a schematic diagram showing the surface state of the inner peripheral surface of the flexible external gear in the zone Z1 of FIG. 5 .
  • 6B is a schematic diagram showing the surface state of the inner peripheral surface of the flexible external gear in the zone Z2 of FIG. 5 .
  • FIG. 7 is an enlarged schematic view of a region Z1 in FIG. 2B .
  • FIG. 8A is a schematic diagram showing the surface state of the external teeth in the zone Z1 of FIG. 7 .
  • FIG. 8B is a schematic diagram showing the surface state of the external teeth in the zone Z2 of FIG. 7 .
  • FIG. 9 is a conceptual explanatory diagram for illustrating the operation of the long-axis side and the short-axis side of the tapered surface of the above-mentioned harmonic gear device.
  • Fig. 10 is a cross-sectional view showing an example of a robot using the above-mentioned harmonic gear device.
  • FIG. 11 is a schematic explanatory view showing the process of machining the inner peripheral surface of the flexible external gear of the harmonic gear device.
  • 12A is a schematic cross-sectional view showing a rolling roller and a chuck member used for machining the inner peripheral surface of the flexible external gear of the harmonic gear device.
  • 12B is a schematic side view showing a rolling roller and a chuck member used for machining the inner peripheral surface of the flexible external gear of the harmonic gear device.
  • Fig. 13A is a schematic cross-sectional view showing a chuck member of a modified example.
  • FIG. 13B is a schematic enlarged view of a region Z1 in FIG. 13A .
  • Fig. 14 is a schematic explanatory view showing the process of machining the external teeth of the flexible external gear of the harmonic gear device.
  • 15A is a schematic cross-sectional view showing a hob used for machining the external teeth of the flexible external gear of the harmonic gear device.
  • 15B is a schematic side view showing a hob used for machining the external teeth of the flexible external gear of the harmonic gear device.
  • 16A is a schematic cross-sectional view showing a tool used for machining the external teeth of the flexible external gear of the harmonic gear device.
  • 16B is a schematic side view showing a tool used for machining the external teeth of the flexible external gear of the harmonic gear device.
  • 17A is a cross-sectional view illustrating a schematic configuration of a harmonic gear device according to a modified example of the embodiment.
  • FIG. 17B is an enlarged view of the area Z1 of FIG. 17A .
  • Fig. 18A is a schematic diagram showing a main part of the harmonic gear device according to the embodiment.
  • FIG. 18B is a schematic diagram showing the surface state of the internal teeth in the region Z1 of FIG. 18A .
  • FIG. 18C is a schematic diagram showing the surface state of the internal teeth in the zone Z2 of FIG. 18B .
  • FIGS. 1A to 5 The drawings referred to in the present disclosure are all schematic diagrams, and the respective ratios of the sizes and thicknesses of the constituent elements in the drawings are not necessarily limited to reflect actual dimensional ratios.
  • FIGS. 2A to 3B the tooth shapes, dimensions, and number of teeth of the internal teeth 21 and the external teeth 31 are schematically shown for illustration only, and are not intended to be limited to the illustrated shapes.
  • a harmonic gear device 1 is a gear device including a rigid internal gear 2 , a flexible external gear 3 , and a wave generator 4 .
  • an annular flexible external gear 3 is arranged inside an annular rigid internal gear 2
  • a wave generator 4 is further arranged inside the flexible external gear 3 .
  • the wave generator 4 locally meshes the external teeth 31 of the flexible external gear 3 with the internal teeth 21 of the rigid internal gear 2 by bending the flexible external gear 3 into a non-circular shape.
  • the wave generator 4 rotates, the meshing position of the internal teeth 21 and the external teeth 31 moves along the circumferential direction of the rigid internal gear 2, and a flexible force is generated between the two gears (the rigid internal gear 2 and the flexible external gear 3).
  • the external gear 3 rotates relative to the rigid internal gear 2 according to the difference in the number of teeth.
  • the rigid internal gear 2 is fixed, the flexible external gear 3 rotates with the relative rotation of both gears.
  • a rotational output decelerated by a relatively high reduction ratio according to the difference in the number of teeth of both gears can be obtained from the flexible external gear 3 .
  • the wave generator 4 that flexes the flexible external gear 3 has a non-circular cam 41 and a bearing 42 that are driven to rotate around the input side rotation axis Ax1 (see FIG. 1A ).
  • the bearing 42 is disposed between the outer peripheral surface 411 of the cam 41 and the inner peripheral surface 301 of the flexible external gear 3 .
  • the inner ring 422 of the bearing 42 is fixed on the outer peripheral surface 411 of the cam 41 , and the outer ring 421 of the bearing 42 is pressed by the cam 41 via the ball-shaped rolling element 423 to be elastically deformed.
  • the outer ring 421 can rotate relative to the inner ring 422 due to the rolling of the rolling elements 423, when the non-circular cam 41 rotates, the rotation of the inner ring 422 is not transmitted to the outer ring 421, but is transmitted by the cam. 41
  • the external teeth 31 of the pressed flexible external gear 3 undergo harmonic motion. Due to the harmonic motion of the external teeth 31, the meshing position of the internal teeth 21 and the external teeth 31 moves along the circumferential direction of the rigid internal gear 2 as described above, so that the flexible external gear 3 and the rigid internal gear 2 generate contact. relative rotation.
  • the wave generator 4 having the bearing 42 achieves power transmission through the meshing of the internal teeth 21 and the external teeth 31 while flexing the flexible external gear 3 .
  • the rotation of the wave generator 4 requires additional energy, resulting in a decrease in power transmission efficiency or due to the load applied to the bearing 42. shortened lifespan due to increase.
  • the indentation caused by the bite of the wear powder into the outer ring 421 or the inner ring 422 of the bearing 42 and the rolling element 423 is the origin, and the outer ring 421, the inner ring 422 and the rolling elements
  • the surface of any of the bodies 423 may be damaged. Such damage (exfoliation of the surface origin type) leads to deterioration of the quality, characteristics, etc.
  • the harmonic gear device 1 suppresses the occurrence of fretting wear by the following configuration, and hardly causes a decrease in reliability.
  • the harmonic gear device 1 of the present embodiment includes an annular rigid internal gear 2 having internal teeth 21 , an annular flexible external gear 3 having external teeth 31 , and a wave generating device 4.
  • the flexible external gear 3 is disposed inside the rigid internal gear 2 .
  • the wave generator 4 is disposed inside the flexible external gear 3 and causes the flexible external gear 3 to bend.
  • the wave generator 4 has a non-circular cam 41 that is rotationally driven around the rotation axis Ax1 , and a bearing 42 that is attached to the outside of the cam 41 .
  • the harmonic gear unit 1 deforms the flexible external gear 3 along with the rotation of the cam 41, so that a part of the external teeth 31 meshes with a part of the internal teeth 21, so that the flexible external gear 3 and the rigid internal gear 2 have a different number of teeth. And relative rotation is performed with respect to the rigid internal gear 2 .
  • the first region R1 located on the back side of the external teeth 31 in the inner peripheral surface 301 of the flexible external gear 3 has a higher surface roughness than the second region R2 other than the first region R1 . Small.
  • the contact portion of the flexible external gear 3 with the bearing 42 has a surface state in which it is easy to maintain a state covered with the lubricant Lb1 (see FIG. 4 ).
  • the back side of the external teeth 31 pressed by the bearing 42 is provided with the first region R1 whose surface roughness is smaller than the other surface roughness. It is easy to maintain the state covered with lubricant Lb1.
  • the harmonic gear device 1 of the present embodiment suppresses the occurrence of fretting wear by preventing "lubricant depletion" in which the lubricant Lb1 is insufficient or exhausted at the contact portion between the outer ring 421 and the flexible external gear 3 .
  • the first region R1 having a surface roughness smaller than the second region R2 on the back side of the external teeth 31 in the inner peripheral surface 301 of the flexible external gear 3, the flexible external gear 3 and the wave
  • the contact portion of the generator 4 maintains sufficient lubricant Lb1.
  • the surface of the contact portion of the flexible external gear 3 with the bearing 42 (outer ring 421 ) is covered with the lubricant Lb1, and the occurrence of fretting wear is suppressed.
  • the harmonic gear device 1 of the present embodiment it is difficult to cause troubles caused by fretting wear between (the outer ring 421 of) the bearing 42 and the flexible external gear 3 , and it is possible to provide reliability Descending harmonic gearing 1. Furthermore, since the harmonic gear device 1 of this embodiment is less prone to reliability degradation even when used for a long period of time, the transmission efficiency of the harmonic gear device 1 is improved, its life is extended, and its performance is improved.
  • the external teeth 31 located at both ends of the long-axis direction of the flexible external gear 3 bent into an ellipse (non-circular shape) press the internal surface of the rigid internal gear 2 like a wedge. tooth 21, whereby the external tooth 31 meshes with the internal tooth 21 to obtain a rotational output. Therefore, in a state where the external teeth 31 are pressed against the internal teeth 21 , the external teeth 31 and the internal teeth 21 rub against each other, particularly at the contact portion between the external teeth 31 and the internal teeth 21 .
  • the harmonic gear device 1 of the present embodiment reduces the friction between the external teeth 31 and the internal teeth 21 by the following configuration, thereby making it difficult to reduce the power transmission efficiency.
  • At least one of the external teeth 31 and the internal teeth 21 includes a rolling surface 300 .
  • the rolling surface 300 is not formed by cutting metal crystal grains, but is formed by not cutting metal crystal grains (rolling processing). Therefore, the rolling surface 300 included in at least one of the external teeth 31 and the internal teeth 21 has a smooth surface state in which metal crystal grains are not sheared.
  • the rolling surface 300 only needs to be provided on at least one of the outer teeth 31 and the inner teeth 21 .
  • the rolling surface 300 provided on the external teeth 31 is referred to as the "first rolling surface”
  • the rolling surface provided on the internal teeth 21 is referred to as the "first rolling surface”.
  • the rolling surface 200 (see FIG. 18A ) of the tooth 21 is called "second rolling surface”.
  • the rolling surface 300 is provided only on the outer teeth 31 of the outer teeth 31 and the inner teeth 21 .
  • the rolling surface 300 includes the “first rolling surface” provided on the external teeth 31 .
  • the rolling surface (second rolling surface) on the side of the internal teeth 21 will be described in another embodiment.
  • the harmonic gear device 1 constitutes an actuator 100 together with a drive source 101 and an output unit 102 .
  • the actuator 100 of the present embodiment includes the harmonic gear device 1 , the drive source 101 and the output unit 102 .
  • the drive source 101 rotates the wave generator 4 .
  • the output unit 102 takes out the rotational force of either the rigid internal gear 2 or the flexible external gear 3 as an output.
  • the harmonic gear device 1 of this embodiment constitutes a joint device 130 for a robot together with a first member 131 and a second member 132 .
  • the robot joint device 130 of this embodiment includes the harmonic gear device 1 , the first member 131 and the second member 132 .
  • the first member 131 is fixed to the rigid internal gear 2 .
  • the second member 132 is fixed to the flexible external gear 3 .
  • the harmonic gear device 1 the flexible external gear 3 rotates relative to the rigid internal gear 2 , whereby the first member 131 and the second member 132 in the robot joint device 130 relatively rotate.
  • the reliability of the harmonic gear device 1 is less likely to be lowered.
  • annular means a shape such as a circle (ring) that forms a space (region) surrounded on the inside at least when viewed from above, and is not limited to a circular shape (circle) that is a perfect circle when viewed from above. Ring), for example, oval shape and polygonal shape etc. are also possible. Furthermore, for example, it may have a bottom 322 like a cup-shaped flexible external gear 3, and if the body part 321 is annular, it may be called a "ring-shaped" flexible external gear 3.
  • the "rigidity” mentioned in the present disclosure refers to the property of an object to resist deformation when an external force is applied to the object and the object is about to deform. In other words, a rigid object is difficult to deform even when an external force is applied.
  • “flexibility” mentioned in the present disclosure refers to the property that an object elastically deforms (bends) when an external force is applied to the object. In other words, a flexible object is prone to elastic deformation when an external force is applied. Therefore, "rigid” and “flexible” have opposite meanings.
  • rigidity of the rigid internal gear 2 and “flexibility” of the flexible external gear 3 are used in relative meanings. That is, the “rigidity” of the rigid internal gear 2 means that the rigid internal gear 2 has relatively high rigidity at least compared with the flexible external gear 3 , that is, the rigid internal gear 2 is hardly deformed even if an external force is applied to the rigid internal gear 2 .
  • the "flexibility" of the flexible external gear 3 means that at least compared with the rigid internal gear 2, the flexible external gear 3 has relatively high flexibility, that is to say, the flexible external gear 3 is easily elastic when an external force is applied. out of shape.
  • one side of the rotation axis Ax1 (right side in FIG. 1A ) is sometimes referred to as an “input side”, and the other side of the rotation axis Ax1 (left side in FIG. 1A ) is sometimes referred to as an “output side”. ". That is, in the example of FIG. 1A , the flexible external gear 3 has the opening surface 35 on the "input side” of the rotation axis Ax1.
  • the terms "input side” and “output side” are merely labels for explanation, and do not mean to limit the positional relationship between the input and output viewed from the harmonic gear device 1 .
  • non-circular shape refers to a shape that is not a perfect circle, and includes, for example, an oval shape, an oblong shape, and the like.
  • the non-circular cam 41 of the wave generator 4 has an elliptical shape. That is, in the present embodiment, the wave generator 4 bends the flexible external gear 3 into an elliptical shape.
  • the "elliptical shape” mentioned in this disclosure refers to the entire shape in which a perfect circle is flattened so that the intersection point of the major axis and the minor axis orthogonal to each other is located at the center, and is not limited to the relationship between two fixed points on a plane.
  • the curve formed by the set of points whose sum of distance is constant is called “ellipse” in mathematics. That is to say, the cam 41 in the present embodiment can be a curved line formed by a collection of points whose distances from two fixed points on a plane are constant as a mathematical "ellipse", or it can be a mathematical "ellipse".
  • the "ellipse” above is an ellipse like an oblong.
  • the drawings referred to in the present disclosure are all schematic diagrams, and the respective ratios of sizes and thicknesses of the constituent elements in the drawings are not necessarily limited to reflect actual dimensional ratios. Therefore, for example, in FIG. 2A , the shape of the cam 41 of the wave generator 4 is a slightly larger elliptical shape, but the actual shape of the cam 41 is not intended to be limited.
  • the "axis of rotation” used in this disclosure refers to a virtual axis (straight line) that becomes the center of the rotational motion of the rotating body. That is, the rotation axis Ax1 is a virtual axis without a real body.
  • the wave generator 4 rotates around the rotation axis Ax1.
  • the "internal teeth” and “external teeth” mentioned in the present disclosure respectively refer to a collection (group) of a plurality of "teeth” rather than a single “teeth”. That is, the internal teeth 21 of the rigid internal gear 2 are constituted by a collection of a plurality of teeth formed on the inner peripheral surface of the rigid internal gear 2 . Similarly, the external teeth 31 of the flexible external gear 3 are composed of a set of teeth formed on the outer peripheral surface of the flexible external gear 3 .
  • the "parallel” mentioned in this disclosure refers to the situation that as long as two straight lines on a plane are extended to any position and do not intersect, that is to say, except that the angle between the two is strictly 0 degrees (or 180 degrees) Except for some cases, the angle between the two is in the relationship of an error range that converges to a few degrees (for example, less than 10 degrees) relative to 0 degrees.
  • the “orthogonal” mentioned in this disclosure means that the angle between the two converges to a few degrees (for example, less than 10 degrees) relative to 90 degrees, except that the angle between the two intersects strictly at 90 degrees. relationship to the margin of error.
  • FIG. 1A is a cross-sectional view showing a schematic configuration of a harmonic gear device 1
  • FIG. 1B is an enlarged view of a region Z1 in FIG. 1A
  • FIG. 2A is a schematic view of the harmonic gear device 1 viewed from the input side of the rotation axis Ax1 (the right side of FIG. 1A )
  • FIG. 2B is an enlarged view of a region Z1 in FIG. 2A
  • Fig. 3A is a schematic exploded perspective view of the harmonic gear unit 1 viewed from the output side of the rotary axis Ax1 (left side in Fig. 1A).
  • FIG. 3B is a schematic exploded perspective view of the harmonic gear device 1 viewed from the input side of the rotary axis Ax1.
  • 4 is a cross-sectional view showing a schematic configuration of the actuator 100 including the harmonic gear device 1 and the robot joint device 130 .
  • the harmonic gear device 1 of the present embodiment includes the rigid internal gear 2 , the flexible external gear 3 and the wave generator 4 .
  • the materials of the rigid internal gear 2, the flexible external gear 3, and the wave generator 4, which are the structural elements of the harmonic gear device 1 are stainless steel, cast iron, carbon steel for mechanical structure, chrome-molybdenum steel, phosphorus Metals such as bronze or aluminum bronze.
  • the metal mentioned here includes metals subjected to surface treatment such as nitriding treatment.
  • the harmonic gear device 1 As an example of the harmonic gear device 1 , a cup-shaped wave speed reduction device is illustrated. That is, the cup-shaped flexible external gear 3 is used in the harmonic gear device 1 of the present embodiment. The wave generator 4 is combined with the flexible external gear 3 so as to be accommodated in the cup-shaped flexible external gear 3 .
  • the harmonic gear unit 1 is used in a state where the rigid internal gear 2 is fixed to the input side case 111 (see FIG. 4 ) and the output side case 112 (see FIG. 4 ). Accordingly, the flexible external gear 3 relatively rotates with respect to the fixed member (input-side housing 111 and the like) along with the relative rotation of the rigid internal gear 2 and the flexible external gear 3 .
  • the harmonic gear device 1 when the harmonic gear device 1 is used as the actuator 100, by applying a rotational force as an input to the wave generator 4, it is possible to extract a rotational force as an output from the flexible external gear 3. rotational force. That is, the harmonic gear device 1 operates with the rotation of the wave generator 4 as an input rotation and with the rotation of the flexible external gear 3 as an output rotation. Accordingly, in the harmonic gear device 1 , it is possible to obtain an output rotation decelerated by a high reduction ratio relative to the input rotation.
  • the input side rotation axis Ax1 and the output side rotation axis Ax2 are on the same straight line.
  • the rotation axis Ax1 on the input side and the rotation axis Ax2 on the output side are coaxial.
  • the rotation axis Ax1 on the input side is the rotation center of the wave generator 4 to which the input rotation is applied
  • the rotation axis Ax1 on the output side is the rotation center of the flexible external gear 3 which generates the output rotation. That is, in the harmonic gear device 1 , on the same axis, an output rotation decelerated by a high reduction ratio relative to the input rotation can be obtained.
  • the rigid internal gear 2 is also called a circular spline, and is an annular member having internal teeth 21 .
  • the rigid internal gear 2 has an annular shape in which at least the inner peripheral surface is a perfect circle in plan view.
  • internal teeth 21 are formed along the circumferential direction of the rigid internal gear 2 .
  • the plurality of teeth constituting the internal teeth 21 all have the same shape and are provided at equal intervals over the entire area in the circumferential direction of the inner peripheral surface of the rigid internal gear 2 . That is to say, the pitch circle of the internal teeth 21 is a perfect circle in plan view.
  • the rigid internal gear 2 has a predetermined thickness in the direction of the rotation axis Ax1. Internal teeth 21 are formed over the entire length of the rigid internal gear 2 in the thickness direction. The tooth directions of the internal teeth 21 are all parallel to the rotation axis Ax1.
  • the rigid internal gear 2 is fixed to the input-side housing 111 (see FIG. 4 ), the output-side housing 112 (see FIG. 4 ), and the like. Therefore, a plurality of fixing holes 22 for fixing are formed in the rigid internal gear 2 (see FIGS. 3A and 3B ).
  • the flexible external gear 3 is also called a flex spline, and is an annular member having external teeth 31 .
  • the flexible external gear 3 is formed into a cup shape using a relatively thin metal elastic body (metal plate). That is, the flexible external gear 3 has flexibility due to its relatively small (thin) thickness.
  • the flexible external gear 3 has a cup-shaped body portion 32 .
  • the main body part 32 has a body part 321 and a bottom part 322 . In a state where the flexible external gear 3 is not elastically deformed, at least the inner peripheral surface 301 of the trunk portion 321 has a cylindrical shape that is a perfect circle in plan view.
  • the central axis of the body part 321 coincides with the rotation axis Ax1.
  • the bottom portion 322 is disposed on one opening surface of the trunk portion 321 and has a disc shape that is a perfect circle in plan view.
  • the bottom portion 322 is disposed on the opening surface near the output side of the rotation axis Ax1 among the pair of opening surfaces of the body portion 321 .
  • the body part 32 has a bottomed cylindrical cup shape that is open on the input side of the rotation axis Ax1 by the whole of the body part 321 and the bottom part 322 .
  • the opening surface 35 is formed on the end surface opposite to the bottom portion 322 in the direction of the rotation axis Ax1 of the flexible external gear 3 .
  • the flexible external gear 3 has a cylindrical shape having an opening surface 35 on one side in the tooth direction D1 (here, the input side of the rotation axis Ax1).
  • the trunk portion 321 and the bottom portion 322 are integrally formed of one metal member, whereby a seamless main body portion 32 can be realized.
  • the wave generator 4 and the flexible external gear 3 are combined so that the non-circular (elliptical) wave generator 4 is fitted inside the trunk portion 321 .
  • the flexible external gear 3 receives an external force in the radial direction (direction perpendicular to the rotation axis Ax1 ) from the wave generator 4 from the inside toward the outside, thereby being elastically deformed into a non-circular shape.
  • the body portion 321 of the flexible external gear 3 is elastically deformed into an elliptical shape. That is, the state where the flexible external gear 3 is not elastically deformed refers to the state where the wave generator 4 is not combined with the flexible external gear 3 .
  • the elastically deformed state of the flexible external gear 3 refers to the combined state of the wave generator 4 and the flexible external gear 3 .
  • the wave generator 4 is fitted into an end portion of the inner peripheral surface 301 of the trunk portion 321 on the side opposite to the bottom portion 322 (input side of the rotation axis Ax1 ).
  • the wave generator 4 is fitted into the end portion on the opening surface 35 side in the direction of the rotation axis Ax1 of the body portion 321 of the flexible external gear 3 . Therefore, in the state where the flexible external gear 3 is elastically deformed, the end of the flexible external gear 3 on the opening surface 35 side in the direction of the rotation axis Ax1 deforms more than the end on the bottom 322 side, and becomes closer to the flexible external gear 3 .
  • the shape of the oval shape is not limited to the oval shape.
  • the inner peripheral surface 301 of the body portion 321 of the flexible external gear 3 includes an inclination with respect to the rotation axis Ax1.
  • the tapered surface 302 (see Figure 9).
  • external teeth 31 are formed along the circumferential direction of the body portion 321 at least at an end portion on the side opposite to the bottom portion 322 (input side of the rotation axis Ax1 ) of the outer peripheral surface of the body portion 321 .
  • the external teeth 31 are provided at least at an end portion on the opening surface 35 side in the direction of the rotation axis Ax1 in the body portion 321 of the flexible external gear 3 .
  • the plurality of teeth constituting the external teeth 31 all have the same shape and are provided at equal intervals over the entire area in the circumferential direction of the outer peripheral surface of the flexible external gear 3 . That is, the pitch circles of the external teeth 31 are perfect circles in plan view when the flexible external gear 3 is not elastically deformed.
  • the external teeth 31 are formed only within a certain width range from the end edge of the trunk portion 321 on the opening surface 35 side (input side of the rotation axis Ax1). Specifically, external teeth 31 are formed on the outer peripheral surface of at least a portion (end portion on the side of the opening surface 35 ) into which the wave generator 4 is fitted in the direction of the rotation axis Ax1 in the trunk portion 321 . The tooth directions of the external teeth 31 are all parallel to the rotation axis Ax1.
  • any tooth direction of the internal teeth 21 of the rigid internal gear 2 and the external teeth 31 of the flexible external gear 3 is parallel to the rotation axis Ax1. Therefore, in the present embodiment, the "tooth direction D1" is a direction parallel to the rotation axis Ax1. Moreover, the dimension of the tooth direction D1 of the internal teeth 21 is the tooth width of the internal teeth 21, and similarly, the dimension of the tooth direction D1 of the external teeth 31 is the tooth width of the external teeth 31, so the tooth direction D1 is the same as the tooth width direction. righteous.
  • the rotation of the flexible external gear 3 is taken out as the output rotation. Therefore, the output unit 102 of the actuator 100 is attached to the flexible external gear 3 (see FIG. 4 ).
  • a plurality of mounting holes 33 for mounting a shaft serving as the output unit 102 are formed in the bottom portion 322 of the flexible external gear 3 .
  • a penetrating hole 34 is formed at a central portion of the bottom portion 322 . The wall around the through hole 34 in the bottom 322 is thicker than other parts of the bottom 322 .
  • the flexible external gear 3 configured in this way is disposed inside the rigid internal gear 2 .
  • the flexible external gear 3 is connected to the rigid internal gear 2 so that only the end portion on the side opposite to the bottom 322 (the input side of the rotation axis Ax1 ) of the outer peripheral surface of the body portion 321 is inserted into the rigid internal gear 2 . 2 to combine. That is, the portion (the end portion on the side of the opening surface 35 ) into which the wave generator 4 is fitted in the direction of the rotation axis Ax1 of the body portion 321 of the flexible external gear 3 is inserted inside the rigid internal gear 2 .
  • external teeth 31 are formed on the outer peripheral surface of the flexible external gear 3
  • internal teeth 21 are formed on the inner peripheral surface of the rigid internal gear 2 . Therefore, in a state where the flexible external gear 3 is arranged inside the rigid internal gear 2 , the external teeth 31 and the internal teeth 21 face each other.
  • the number of internal teeth 21 of the rigid internal gear 2 is 2N greater than the number of external teeth 31 of the flexible external gear 3 (N is a positive integer).
  • N is "1”
  • the number of teeth of the flexible external gear 3 (of the external teeth 31 ) is "2" larger than the number of teeth of the rigid internal gear 2 (of the internal teeth 21 ).
  • the difference in the number of teeth between the flexible external gear 3 and the rigid internal gear 2 defines the reduction ratio of the output rotation relative to the input rotation in the harmonic gear device 1 .
  • the rotation axis Ax1 is set so that the center of the outer tooth 31 in the tooth direction D1 faces the center of the inner tooth 21 in the tooth direction D1.
  • the relative position of the flexible external gear 3 and the rigid internal gear 2 in the direction of that is, in the external teeth 31 of the flexible external gear 3 and the internal teeth 21 of the rigid internal gear 2 , the positions of the centers in the tooth direction D1 are aligned with the same position in the direction of the rotation axis Ax1 .
  • the dimension (tooth width) of the external teeth 31 in the tooth direction D1 is larger than the dimension (tooth width) of the internal teeth 21 in the tooth direction D1.
  • the internal teeth 21 converge within the range of the tooth direction of the external teeth 31 .
  • the external teeth 31 protrude to at least one side in the tooth direction D1 relative to the internal teeth 21 .
  • the external teeth 31 protrude toward both sides (the input side and the output side of the rotation axis Ax1 ) in the tooth direction D1 with respect to the internal teeth 21 .
  • the pitch circles of the external teeth 31 that draw a perfect circle are set to be larger than those drawn in the same way.
  • the pitch circle of the round internal teeth 21 is one circle smaller. That is, in a state where the flexible external gear 3 is not elastically deformed, the external teeth 31 and the internal teeth 21 face each other with gaps therebetween, and are not in mesh with each other.
  • the flexure The external teeth 31 of the rigid external gear 3 partially mesh with the internal teeth 21 of the rigid internal gear 2 . That is, as shown in FIG. 2A , the body portion 321 (at least the end portion on the opening surface 35 side) of the flexible external gear 3 is elastically deformed into an elliptical shape, whereby the external teeth located at both ends of the elliptical shape in the major axis direction 31 meshes with the internal teeth 21.
  • the major diameter of the pitch circle of the elliptical external teeth 31 coincides with the diameter of the pitch circle of the perfect circular internal teeth 21, and the minor diameter of the pitch circle of the elliptical external teeth 31 is smaller than that of the perfect circular internal teeth 21.
  • the diameter of the pitch circle is small.
  • the wave generator 4 is also called a wave generator (wave generator), which is a component that makes the flexible external gear 3 deflect, thereby causing the external teeth 31 of the flexible external gear 3 to generate harmonic motion.
  • the wave generator 4 has a non-circular outer peripheral shape, specifically an elliptical shape in plan view.
  • the wave generator 4 has a cam 41 having a non-circular shape (here, an elliptical shape) and a bearing 42 fitted to the outer periphery of the cam 41 . That is, the cam 41 and the bearing 42 are combined such that the non-circular (ellipse) cam 41 is fitted inside the inner ring 422 of the bearing 42 . Accordingly, the bearing 42 is elastically deformed into a non-circular shape by receiving an external force from the cam 41 in the radial direction (direction perpendicular to the rotation axis Ax1 ) from the inner side toward the outer side of the inner ring 422 . That is, the state where the bearing 42 is not elastically deformed refers to the state where the cam 41 is not combined with the bearing 42 . On the contrary, the elastically deformed state of the bearing 42 refers to the combined state of the cam 41 and the bearing 42 .
  • the cam 41 is a member having a non-circular shape (here, an elliptical shape) that is rotationally driven around the input-side rotational axis Ax1.
  • the cam 41 has an outer peripheral surface 411 (see FIG. 1B ), and at least the outer peripheral surface 411 is formed of an elliptical metal plate in plan view.
  • the cam 41 has a predetermined thickness in the direction of the rotation axis Ax1 (that is, the tooth direction D1).
  • the cam 41 has rigidity equivalent to that of the rigid internal gear 2 .
  • the thickness of the cam 41 is smaller (thinner) than that of the rigid internal gear 2 .
  • the rotation of the wave generator 4 is used as the input rotation. Therefore, the input unit 103 of the actuator 100 is attached to the wave generator 4 (see FIG. 4 ).
  • a cam hole 43 for attaching a shaft serving as the input unit 103 is formed at the center of the cam 41 of the wave generator 4 .
  • the bearing 42 has an outer ring 421 , an inner ring 422 and a plurality of rolling elements 423 .
  • the bearing 42 is constituted by a deep groove ball bearing using spherical balls as the rolling elements 423 .
  • Both the outer ring 421 and the inner ring 422 are annular members. Both the outer ring 421 and the inner ring 422 are annular members formed using a thin metal elastic body (metal plate). That is to say, both the outer ring 421 and the inner ring 422 have flexibility due to their relatively small (thin) thickness. In the present embodiment, both the outer ring 421 and the inner ring 422 have an annular shape that is perfectly circular in plan view when the bearing 42 is not elastically deformed (the cam 41 is not combined with the bearing 42 ). The inner ring 422 is one turn smaller than the outer ring 421 and is disposed inside the outer ring 421 .
  • the inner diameter of the outer ring 421 is larger than the outer diameter of the inner ring 422, a gap is formed between the inner peripheral surface 425 of the outer ring 421 and the outer peripheral surface of the inner ring 422.
  • a plurality of rolling elements 423 are disposed in a gap between the outer ring 421 and the inner ring 422 .
  • the plurality of rolling elements 423 are arranged along the circumferential direction of the outer ring 421 .
  • the plurality of rolling elements 423 are all metal balls (balls) of the same shape, and are arranged at equal intervals over the entire area of the outer ring 421 in the circumferential direction.
  • the bearing 42 further has a cage, and a plurality of rolling elements 423 are held between the outer ring 421 and the inner ring 422 by the cage.
  • the dimensions in the width direction (direction parallel to the rotation axis Ax1 ) of the outer ring 421 and the inner ring 422 are the same as the thickness of the cam 41 . That is, the dimensions in the width direction of the outer ring 421 and the inner ring 422 are smaller than the thickness of the rigid internal gear 2 .
  • the cam 41 is combined with the bearing 42 , whereby the inner ring 422 of the bearing 42 is fixed to the cam 41 , and the inner ring 422 is elastically deformed into an elliptical shape similar to the outer peripheral shape of the cam 41 .
  • the outer ring 421 of the bearing 42 is elastically deformed into an elliptical shape by being pressed by the inner ring 422 via the plurality of rolling elements 423 .
  • both the outer ring 421 and the inner ring 422 of the bearing 42 are elastically deformed into an elliptical shape.
  • the outer ring 421 and the inner ring 422 have elliptical shapes similar to each other.
  • the outer peripheral shape of the wave generator 4 having an elliptical shape viewed from the input side of the rotation axis Ax1 is accompanied by a cam so that the major axis rotates around the rotation axis Ax1. 41 rotations vary.
  • the wave generator 4 configured in this way is disposed inside the flexible external gear 3 .
  • the flexible external gear 3 is combined with the wave generator 4 so that only the end portion on the inner peripheral surface 301 of the trunk portion 321 on the side opposite to the bottom 322 (opening surface 35 side) is fitted to the wave generator 4 .
  • the bearing 42 of the wave generator 4 is arranged between the outer peripheral surface 411 of the cam 41 and the inner peripheral surface 301 of the flexible external gear 3 .
  • the outer diameter of the outer ring 421 in the state where the bearing 42 is not elastically deformed is the same as that of the flexible external gear 3 (body portion 321 ) in the same state where the elastic deformation is not generated.
  • the outer peripheral surface 424 (see FIG. 5 ) of the outer ring 421 in the wave generator 4 is in contact with the inner peripheral surface 301 of the flexible external gear 3 over the entire circumference of the bearing 42 in the circumferential direction.
  • the trunk portion 321 is bent into an elliptical shape (non-circular shape). In this state, the flexible external gear 3 is fixed to the outer ring 421 of the bearing 42 .
  • the outer ring 421 and the flexible external gear 3 are elastically deformed as the cam 41 of the wave generator 4 rotates, and relative rotation may occur between the outer ring 421 and the flexible external gear 3 .
  • This relative rotation is, for example, a few thousandths or a few hundredths of the rotation speed of the cam 41.
  • the relative friction between the outer ring 421 and the flexible external gear 3 due to such relative rotation is fretting wear. one of the reasons.
  • the "gap" in the present disclosure refers to a space that may be generated between opposing surfaces of two objects, and a gap may be generated between the two objects even if the two objects are not separated. In other words, even if two objects are in contact, there is a possibility that a gap may be generated between the two objects although it is small.
  • a gap X1 is formed between the outer peripheral surface 424 of the outer ring 421 and the inner peripheral surface 301 of the flexible external gear 3 which face each other.
  • the outer peripheral surface 424 of the outer ring 421 is basically in contact with the inner peripheral surface 301 of the flexible external gear 3, there is no large gap X1 therebetween.
  • the gap X1 between the outer ring 421 and the flexible external gear 3 is a small gap that can be locally generated between the outer peripheral surface 424 of the outer ring 421 and the inner peripheral surface 301 of the flexible external gear 3 .
  • a microscopic gap X1 is formed between the outer peripheral surface 424 of the outer ring 421 and the inner peripheral surface 301 of the flexible external gear 3 to the extent that the lubricant Lb1 can penetrate.
  • the body part 321 of the flexible external gear 3 is bent into an elliptical shape (non-circular shape), so that the external teeth 31 of the flexible external gear 3 and the rigid The internal teeth 21 of the internal gear 2 mesh locally. That is, when (the trunk portion 321 of) the flexible external gear 3 is elastically deformed into an elliptical shape, two external teeth 31 corresponding to both ends of the elliptical shape in the long-axis direction mesh with the internal teeth 21 .
  • harmonic motion occurs in the external teeth 31 formed on the outer peripheral surface of the flexible external gear 3 . Since the harmonic motion of the external teeth 31 occurs, the meshing position of the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the rigid internal gear 2 , thereby generating relative rotation between the flexible external gear 3 and the rigid internal gear 2 . That is, since the external teeth 31 mesh with the internal teeth 21 at both ends in the direction of the long axis of the ellipse formed by the flexible external gear 3 (the body part 321 of the flexible external gear), the rotation axis passes through the long axis of the ellipse. Ax1 rotates around the center to move the meshing position of the internal teeth 21 and the external teeth 31 .
  • the flexible external gear 3 is deformed with the rotation of the wave generator 4 centered on the rotation axis Ax1, so that a part of the external teeth 31 are aligned with the internal teeth. 21, so that the flexible external gear 3 rotates according to the difference in the number of teeth of the rigid internal gear 2.
  • the difference in the number of teeth between the flexible external gear 3 and the rigid internal gear 2 defines the reduction ratio of the output rotation relative to the input rotation in the harmonic gear device 1 . That is, when the number of teeth of the rigid internal gear 2 is "V1" and the number of teeth of the flexible external gear 3 is "V2", the speed reduction ratio R1 is expressed by the following formula 1.
  • the reduction ratio R1 is "35".
  • the cam 41 rotates one revolution (360 degrees) clockwise about the rotation axis Ax1 when viewed from the input side of the rotation axis Ax1
  • the flexible external gear 3 only rotates counterclockwise about the rotation axis Ax1.
  • the number of teeth differs by an amount of "2" (ie, 10.3 degrees).
  • such a high reduction ratio R1 can be realized by a combination of one-stage gears (the rigid internal gear 2 and the flexible external gear 3 ).
  • the wave gear device 1 only needs to include at least a rigid internal gear 2, a flexible external gear 3, and a wave generator 4, and may also include, for example, the spline bushing 113 described in the column of "(3.2) Actuator". as a constituent element.
  • the actuator 100 includes the harmonic gear device 1 of the present embodiment, a drive source 101 , and an output unit 102 . That is, the actuator 100 includes a drive source 101 and an output portion 102 in addition to the rigid internal gear 2 , the flexible external gear 3 , and the wave generator 4 constituting the harmonic gear device 1 .
  • the actuator 100 includes an input unit 103 , an input side case 111 , an output side case 112 , a spline bush 113 , and a spacer 114 in addition to the harmonic gear unit 1 , the drive source 101 , and the output unit 102 . , the first stopper 115 , the second stopper 116 and the mounting plate 117 .
  • the actuator 100 further includes input side bearings 118, 119, an input side oil seal 120, output side bearings 121, 122 and an output side oil seal 123.
  • the materials of the components other than the driving source 101, the input side oil seal 120 and the output side oil seal 123 in the actuator 100 are stainless steel, cast iron, carbon steel for mechanical structure, chrome molybdenum steel, phosphor bronze or metals such as aluminum bronze.
  • the driving source 101 is a power generation source such as an electric motor (electric motor).
  • the power generated by the driving source 101 is transmitted to the cam 41 of the wave generator 4 in the harmonic gear device 1 .
  • the drive source 101 is connected to a shaft serving as the input unit 103 , and power generated by the drive source 101 is transmitted to the cam 41 via the input unit 103 . Thereby, the drive source 101 can rotate the cam 41 .
  • the output unit 102 is a cylindrical shaft arranged along the rotation axis Ax2 on the output side.
  • the central axis which is the axis of the output unit 102 coincides with the rotation axis Ax2.
  • the output unit 102 is held rotatably around the rotation axis Ax2 by the output side case 112 .
  • the output part 102 is fixed to the bottom 322 of the main body part 32 of the flexible external gear 3 , and rotates together with the flexible external gear 3 around the rotation axis Ax2 . That is, the output unit 102 takes out the rotational force of the flexible external gear 3 as an output.
  • the input unit 103 is a cylindrical shaft arranged along the rotation axis Ax1 on the input side.
  • the central axis that is the axis of the input unit 103 coincides with the rotation axis Ax1.
  • the input unit 103 is held by the input side case 111 so as to be rotatable about the rotation axis Ax1.
  • the input unit 103 is attached to the cam 41 of the wave generator 4, and rotates together with the cam 41 around the rotation axis Ax1. That is, the input unit 103 transmits power (rotational force) generated by the driving source 101 to the cam 41 as an input.
  • the input side rotation axis Ax1 and the output side rotation axis Ax2 are located on the same straight line, so the input unit 103 and the output unit 102 are located on the same axis.
  • the input side housing 111 holds the input unit 103 rotatably via input side bearings 118 and 119 .
  • a pair of input-side bearings 118 and 119 are arranged along the rotation axis Ax1 with a gap therebetween.
  • the shaft serving as the input part 103 penetrates the input side housing 111, and the front end of the input part 103 protrudes from the end surface (the right end surface in FIG. 4 ) on the input side of the rotation axis Ax1 of the input side housing 111.
  • the input side oil seal 120 closes the gap between the input side end surface of the rotation shaft Ax1 of the input side housing 111 and the input part 103 .
  • the output side housing 112 holds the output unit 102 rotatably via output side bearings 121 and 122 .
  • a pair of output-side bearings 121 and 122 are arranged along the rotation axis Ax2 with a gap between them.
  • the shaft serving as the output part 102 penetrates the output side housing 112, and the front end part of the output part 102 protrudes from the output side end surface (the left end surface in FIG. 4 ) of the rotation axis Ax1 in the output side housing 112. .
  • the output side oil seal 123 closes the gap between the output side end surface of the output side housing 112 on the output side of the rotation shaft Ax1 and the output portion 102 .
  • the input-side housing 111 and the output-side housing 112 sandwich the rigid internal gear 2 of the harmonic gear unit 1 from both sides in the direction parallel to the rotation axis Ax1, that is, the tooth direction D1. state combined with each other.
  • the input side case 111 is in contact with the rigid internal gear 2 from the input side of the rotation axis Ax1
  • the output side case 112 is in contact with the rigid internal gear 2 from the output side of the rotation axis Ax1 .
  • the input side case 111 and the output side case are connected by screws (bolts) through a plurality of fixing holes 22 .
  • the body 112 is fastened and fixed.
  • the input-side housing 111, the output-side housing 112, and the rigid internal gear 2 are integrated with each other.
  • the rigid internal gear 2 constitutes the outer contour of the actuator 100 together with the input side housing 111 and the output side housing 112 .
  • the spline bushing 113 is a cylindrical member for connecting the shaft serving as the input portion 103 to the cam 41 .
  • the spline bushing 113 is inserted into the cam hole 43 formed in the cam 41 , and the shaft serving as the input unit 103 is inserted into the spline bushing 113 so as to pass through the spline bushing 113 .
  • the movement of the spline bush 113 relative to both the cam 41 and the input portion 103 is restricted in the rotational direction centering on the rotational axis Ax1, and the spline bush 113 is restricted in the direction parallel to the rotational axis Ax1.
  • 113 is at least movable relative to the input unit 103 .
  • a spline connection structure can be realized as a connection structure between the input unit 103 and the cam 41 .
  • the cam 41 can move along the rotation axis Ax1 with respect to the input part 103, and rotates together with the input part 103 centering on the rotation axis Ax1.
  • the spacer 114 is a member that fills the gap between the spline bush 113 and the cam 41 .
  • the first stopper 115 is a component that prevents the spline bushing 113 from coming off the cam 41 .
  • the first stopper 115 is composed of, for example, an E-ring, and is attached to the spline bush 113 at a position on the input side of the rotation axis Ax1 when viewed from the cam 41 .
  • the second stopper 116 is a member that prevents the input portion 103 from coming off the spline bush 113 .
  • the second stopper 116 is composed of, for example, an E-ring, and is attached to the input portion 103 so as to be in contact with the spline bush 113 from the output side of the rotation shaft Ax1.
  • the mounting plate 117 is a member for mounting the shaft serving as the output portion 102 to the bottom portion 322 of the flexible external gear 3 .
  • a plurality of mounting holes 33 are passed through using screws (bolts). Fasten and fix the mounting plate 117 and the flange portion.
  • the shaft serving as the output unit 102 is fixed to the bottom portion 322 of the flexible external gear 3 .
  • the lubricant Lb1 is sealed inside the outer contour of the actuator 100 constituted by the input-side housing 111 , the output-side housing 112 , and the rigid internal gear 2 . That is, in the space surrounded by the input-side housing 111 , the output-side housing 112 , and the rigid internal gear 2 , there is a “lubricant reservoir” capable of storing the lubricant Lb1 in liquid or gel state.
  • a lubricant in a liquid or gel state is injected into the meshing portion of the internal teeth 21 and the external teeth 31 and between the outer ring 421 and the inner ring 422 of the bearing 42 .
  • Lb1 is liquid lubricating oil (oil).
  • the lubricant Lb1 also enters the gap X1 between the outer ring 421 (outer peripheral surface 424 ) of the bearing 42 and the flexible external gear 3 .
  • the lubricant Lb1 is placed only on the lower portion of the outer contour of the actuator 100 (lead The lower part in the vertical direction) stores the lubricant Lb1. Therefore, with regard to the external teeth 31 and the outer ring 421 of the bearing 42 , etc., only a part in the rotational direction is immersed in the lubricant Lb1 in the state of FIG. 4 .
  • the output part 102 rotates from this state accompanying the rotation of the input part 103
  • the outer ring 421 and the flexible external gear 3 also rotate around the rotation axis Ax1, so as a result, the external teeth 31 and the outer ring 421 of the bearing 42 etc. Immerse in lubricant Lb1 in the direction of rotation.
  • the robot joint device 130 of this embodiment includes the harmonic gear device 1 of this embodiment, a first member 131 , and a second member 132 . That is, the robot joint device 130 includes a first member 131 and a second member 132 in addition to the rigid internal gear 2 , the flexible external gear 3 , and the wave generator 4 constituting the harmonic gear device 1 .
  • the first member 131 is a member fixed to the rigid internal gear 2
  • the second member 132 is a member fixed to the flexible external gear 3 . Therefore, in the harmonic gear device 1 , relative rotation occurs between the flexible external gear 3 and the rigid internal gear 2 , and thus relative rotation also occurs between the first member 131 and the second member 132 .
  • the joint device 130 for a robot constitutes a connection site when two or more members (the first member 131 and the second member 132 ) are mutually movably connected (movably connected) via the harmonic gear device 1 .
  • first member 131 and the second member 132 may be directly or indirectly fixed to the rigid internal gear 2 and the flexible external gear 3 , respectively.
  • first member 131 is indirectly coupled (fixed) to the rigid internal gear 2 by being coupled to the output side case 112 .
  • the second member 132 is indirectly coupled (fixed) to the flexible external gear 3 by being coupled to the output portion 102 .
  • the robot joint device 130 configured in this way, for example, when the cam 41 of the wave generator 4 rotates by the power generated by the drive source 101, a relative force is generated between the flexible external gear 3 and the rigid internal gear 2. rotate. And, with the relative rotation of the flexible external gear 3 and the rigid internal gear 2, between the first member 131 and the second member 132, the rotation axis Ax2 on the output side (coaxial with the rotation axis Ax1 on the input side) is The center produces relative rotation. As a result, according to the joint device 130 for a robot, the first member 131 and the second member 132 connected via the harmonic gear device 1 can be driven to rotate relative to each other around the rotation axis Ax1. Thus, the robot joint device 130 can realize various joint mechanisms of robots.
  • FIG. 5 is an enlarged schematic cross-sectional view of a main part of a range corresponding to FIG. 1B .
  • 6A is a schematic diagram showing the surface state of the inner peripheral surface 301 of the flexible external gear 3 in the zone Z1 of FIG. Schematic diagram of the surface state.
  • FIG. 7 is an enlarged schematic view of the area Z1 in FIG. 2B .
  • 8A is a schematic view showing the surface state of the external teeth 31 in the zone Z1 of FIG. 7
  • FIG. 8B is a schematic view showing the surface state of the external teeth 31 in the zone Z2 of FIG. 7 .
  • At least one of the outer ring 421 of the bearing 42 and the external teeth 31 of the flexible external gear 3 is provided with a through hole H1 along the radial direction. It penetrates in the direction and is connected to the gap X1 between the outer ring 421 and the flexible external gear 3 . That is, the inner peripheral surface 425 (refer to FIG. 5 ) serving as the rolling surface of the plurality of rolling elements 423 in the outer ring 421 of the bearing 42 and the inner peripheral surface 425 (see FIG. 5 ) of the external teeth 31 of the flexible external gear 3 that are compatible with the internal teeth 21 At least one of the outer peripheral surfaces of the engaging surfaces communicates with the gap X1 through the through hole H1. Therefore, the lubricant Lb1 can be supplied to the gap X1 between the outer ring 421 and the flexible external gear 3 through the through hole H1.
  • the harmonic gear device 1 of the present embodiment can supply the lubricant Lb1 to the contact portion of the flexible external gear 3 and the wave generator 4 through the through hole H1 by providing the through hole H1, thereby maintaining sufficient Lubricant Lb1.
  • "lubricant depletion" is prevented, the surface of the contact portion between the outer ring 421 and the flexible external gear 3 is covered with the lubricant Lb1, and the occurrence of fretting wear is suppressed.
  • troubles due to fretting wear between the outer ring 421 and the flexible external gear 3 are less likely to occur, and it is possible to provide harmonics with less reliability degradation.
  • gear unit 1 troubles due to fretting wear between the outer ring 421 and the flexible external gear 3 are less likely to occur, and it is possible to provide harmonics with less reliability degradation.
  • the through hole H1 may be provided in at least one of the outer ring 421 and the external teeth 31 of the flexible external gear 3 .
  • the through-holes H1 provided in the outer ring 421 are referred to as "first through-holes”.
  • hole" the through-hole H2 (see FIG. 17B ) provided in the external tooth 31 of the flexible external gear 3 is called a "second through-hole”.
  • the through hole H1 is provided only in the outer ring 421 among the outer ring 421 and the external teeth 31 of the flexible external gear 3 .
  • the through hole H1 includes the “first through hole” provided in the outer ring 421 .
  • the through-hole H2 (second through-hole) on the side of the external teeth 31 of the flexible external gear 3 will be described in "(8) Modification".
  • penetrating along the radial direction in the present disclosure means penetrating along the radial direction, that is, the direction perpendicular to the rotation axis Ax1 , that is, radially. That is, as long as the through hole H1 is provided in the outer ring 421 as in the present embodiment, the through hole H1 only needs to penetrate between the inner peripheral surface 425 and the outer peripheral surface 424 on both sides of the outer ring 421 in the radial direction. For example, It is also possible to be inclined with respect to the radial direction.
  • the through hole H1 (first through hole) provided in the outer ring 421 penetrates the outer ring 421 in the radial direction.
  • one opening surface of the through hole H1 faces the gap X1 between the outer ring 421 and the flexible external gear 3 , and the other opening surface of the through hole H1 opens to the inner peripheral surface 425 of the outer ring 421 . Therefore, one end of the through hole H1 is connected to the gap X1 between the outer ring 421 and the flexible external gear 3 , and the other end is connected to the space between the inner peripheral surface 425 of the outer ring 421 and the outer peripheral surface of the inner ring 422 .
  • the through hole H1 is a circular hole having a circular (perfect circle) cross-sectional shape perpendicular to the radial direction.
  • the center line of the through hole H1 is parallel to the radial direction. That is, the through hole H1 is a hole extending straight in the radial direction from the inner peripheral surface 425 to the outer peripheral surface 424 of the outer ring 421 .
  • the cross-sectional shape of the through hole H1 perpendicular to the radial direction is the same shape over the entire length of the through hole H1 in the radial direction. That is, a cylindrical space is formed inside the through hole H1.
  • the diameter ⁇ 1 (see FIG. 5 ) of the through hole H1 is the smaller of 0.1 times or less and 1.0 mm or less the diameter ⁇ 2 (see FIG. 5 ) of each of the plurality of rolling elements 423 .
  • the diameter ⁇ 1 of the through-hole H1 referred to here refers to the diameter of the through-hole H1 when the cross-sectional shape of the through-hole H1 is a perfect circle. It means the dimension of the minor axis direction of the through-hole H1.
  • the diameter ⁇ 1 of the through hole H1 is not more than 0.1 times the diameter ⁇ 2 of the rolling element 423 and not more than 1.0 mm. According to such a diameter ⁇ 1 of the through hole H1 , the lubricant Lb1 can be efficiently supplied to the gap X1 between the outer ring 421 and the flexible external gear 3 through the through hole H1 .
  • the space between the outer ring 421 and the inner ring 422 is connected to the gap X1 between the outer ring 421 and the flexible external gear 3 through the through hole H1, so the space between the outer ring 421 and the inner ring 422
  • the lubricant Lb1 is supplied to the gap X1 through the through hole H1.
  • the flow of the lubricant Lb1 in the through hole H1 is schematically indicated by dotted arrows.
  • the rolling elements 423 function as a pump and can send the lubricant Lb1 between the outer ring 421 and the inner ring 422 into the gap X1 through the through hole H1.
  • "lubricant depletion" in which the lubricant Lb1 is insufficient or exhausted at the contact portion between the outer ring 421 and the flexible external gear 3 is prevented, and the occurrence of fretting wear is easily suppressed.
  • the harmonic gear device 1 of the present embodiment includes a pump structure for supplying the lubricant Lb1 to the gap X1 through the through hole H1 when the flexible external gear 3 rotates relative to the rigid internal gear 2 .
  • the plurality of rolling elements 423 of the bearing 42 roll in the circumferential direction of the outer ring 421 , so the plurality of rolling elements 423 function as a pump as described above. That is, a plurality of rolling elements 423 constitute a pump structure.
  • the rolling elements 423 roll in the space between the outer ring 421 and the inner ring 422 , thereby increasing the pressure in the space between the outer ring 421 and the inner ring 422 , so that the space between the outer ring 421 and the inner ring 422 increases.
  • the lubricant Lb1 between the inner rings 422 is extruded to the side of the gap X1 through the through hole H1.
  • the rolling elements 423 constitute a positive displacement pump such as a vane pump, and since the lubricant Lb1 is extruded to the gap X1 side with a sufficient pressure, it is easy to supply a sufficient amount of the lubricant Lb1 into the gap X1.
  • the opening surface of the through hole H1 on the inner peripheral surface 425 side of the outer ring 421 opens to the bottom surface of the rolling groove 426 formed on the inner peripheral surface 425 of the outer ring 421 . That is, a rolling groove 426 extending in the circumferential direction over the entire circumference of the outer ring 421 is formed at the center of the inner peripheral surface 425 of the outer ring 421 in the width direction (tooth direction D1), and the plurality of rolling elements 423 along the The rolling groove 426 rolls. Similar rolling grooves 427 are formed on the outer peripheral surface of the inner ring 422 , and a plurality of rolling elements 423 are sandwiched between these rolling grooves 426 , 427 facing each other.
  • the through holes H1 are arranged in the range where the rolling grooves 426 are formed in the width direction (tooth direction D1 ) of the outer ring 421 so as to open to the bottom surface of the rolling grooves 426 of the outer ring 421 .
  • the through-hole H1 is arrange
  • the through hole H1 is arranged at the center of the rolling groove 426 in the width direction (tooth direction D1 ) of the outer ring 421 .
  • the outer ring 421 is in contact with the flexible external gear 3 mainly at both ends of the outer ring 421 in the width direction (tooth direction D1 ). Therefore, the through hole H1 is formed at the center of the outer ring 421 in the width direction (tooth direction D1), so that when the outer ring 421 comes into contact with the flexible external gear 3, the outer ring 421 is less likely to be damaged due to the through hole H1. decrease in strength.
  • the rolling grooves 426 and 427 are formed in an arc shape in cross section perpendicular to the circumferential direction of the outer ring 421 .
  • the curvature of the circular arc of the cross-sectional shape of the rolling grooves 426 and 427 is larger than the curvature of each of the plurality of rolling elements 423 .
  • the radius of curvature of the circular arc of the cross-sectional shape of the rolling grooves 426 and 427 is smaller than the radius of curvature of the rolling element 423 .
  • the opening surface of the through-hole H1 formed in the bottom surface of the rolling groove 426 faces the surface of the rolling element 423 via the gap.
  • the opening surface of the through-hole H1 formed in the bottom surface of the rolling groove 426 faces the surface of the rolling element 423 via the gap.
  • the tracks of the plurality of rolling elements 423 and the opening surface of the outer ring 421 on the inner peripheral surface 425 side of the (first) through hole H1 provided in the outer ring 421 Ensure that there is a distance above the specified value. That is, even when the rolling element 423 exists at a position corresponding to the through hole H1, a distance (gap) equal to or greater than a predetermined value is ensured between the opening surface of the through hole H1 and the rolling element 423, and the through hole H1 Will not be closed by rolling elements 423.
  • the plurality of rolling elements 423 roll, even if the rolling elements 423 pass through the through-hole H1 , they do not collide with the opening edge of the through-hole H1 .
  • the impact caused by the rolling elements 423 colliding with the opening edge of the through-hole H1 can be avoided, and the outer ring 421, the rolling elements 423, etc. can be easily protected from the impact.
  • the through holes H1 include a plurality of first through holes arranged in the outer ring 421 in the circumferential direction of the outer ring 421 .
  • the through-holes H1 are formed only by the first through-holes provided in the outer ring 421 , so all the through-holes H1 are arranged along the circumferential direction of the outer ring 421 .
  • three through-holes H1 are provided in the outer ring 421 .
  • the lubricant Lb1 can be supplied to the gap X1 between the outer ring 421 and the flexible external gear 3 through the through hole H1 at a plurality of places (three places in the present embodiment) in the circumferential direction of the outer ring 421 .
  • the interval P1 of the plurality of through holes H1 is a value other than a multiple of the interval P2 of the plurality of rolling elements 423 .
  • the bearing 42 has 26 rolling elements 423 and has three through-holes H1 in the outer ring 421 .
  • the 26 rolling elements 423 and the three through holes H1 are provided at equal intervals (equal intervals) in the circumferential direction of the outer ring 421, respectively.
  • the interval P1 is a value representing the distance between the centers of two through-holes H1 adjacent in the circumferential direction of the outer ring 421 by an angle around the rotation axis Ax1. The value of the distance between the centers of two rolling elements 423 adjacent in the circumferential direction of the ring 421 .
  • the interval P2 (13.85 degrees) of the plurality of rolling elements 423 is multiplied by any integer, the interval P1 (120 degrees) of the plurality of through-holes H1 does not match the interval P1 (120 degrees), so that the interval P1 cannot be separated. P2 divisible such values.
  • the rolling elements 423 do not simultaneously exist at positions corresponding to all the through-holes H1. That is, in a state where one rolling element 423 is located at a position corresponding to one through-hole H1, the rolling element 423 is not located at a position corresponding to the other two through-holes H1. Therefore, in the harmonic gear device 1 of this embodiment, it is possible to avoid relatively large impacts that may occur when a plurality of rolling elements 423 are simultaneously fitted (or pulled out) into a plurality of through-holes H1, and it is easy to protect the outer ring 421. And rolling elements 423 etc. from impact. In addition, the pump action by the rolling of the rolling elements 423 is also more efficient than when the rolling elements 423 are positioned on all the through holes H1.
  • the first region R1 located on the back side of the external teeth 31 in the inner peripheral surface 301 of the flexible external gear 3 is formed to have a surface roughness higher than that of the second region other than the first region R1.
  • R2 is small. That is, the inner peripheral surface 301 of the flexible external gear 3 includes a first region R1 and a second region R2 having different surface roughnesses.
  • the first region R1 is provided on at least the back side of the external teeth 31 on the inner peripheral surface 301 .
  • the surface roughness of the first region R1 is smaller than that of the second region R2, that is to say, the first region R1 has a smoother surface state.
  • the bearing 42 of the wave generator 4 is in contact with the first region R1 thus provided on the back side of the external teeth 31 .
  • a gap X1 is generated, although small, between the first region R1 on the inner peripheral surface 301 of the flexible external gear 3 and the outer ring 421 of the bearing 42 fitted inside the flexible external gear 3 . Occurrence of fretting wear at the contact portion between the flexible external gear 3 and the outer ring 421 is suppressed by allowing the lubricant Lb1 to penetrate into the gap X1. That is, in the present embodiment, the lubricant Lb1 is held between the first region R1 and the outer peripheral surface 424 (of the bearing 42 ) of the wave generator 4 .
  • the lubricant Lb1 is likely to stay at the contact portion of the flexible external gear 3 with the wave generator 4 , sufficient lubricant Lb1 can be maintained at the contact site.
  • the first region R1 is provided over the entire region of the surface facing the outer peripheral surface 424 (of the bearing 42 ) of the wave generator 4 at least in a direction parallel to the rotation axis Ax1 (tooth direction D1 ). . That is, as shown in FIG. 5 , the entire region of the inner peripheral surface 301 of the flexible external gear 3 that faces the outer peripheral surface 424 of the bearing 42 has a smooth surface state as the first region R1 . As a result, the contact portion of the inner peripheral surface 301 of the flexible external gear 3 with the wave generator 4 is covered with the lubricant Lb1, and the occurrence of fretting wear is suppressed.
  • the first region R1 is formed by, for example, not shearing metal crystal grains such as cutting but not shearing metal crystal grains (rolling). Therefore, the first region R1 provided on the inner peripheral surface 301 at least at the back side of the external teeth 31 has a smooth surface state in which metal crystal grains are not sheared.
  • the second region R2 having a relatively large surface roughness is formed by shearing metal crystal grains such as cutting, grinding, or honing. Therefore, the second region R2 in the inner peripheral surface 301 has a surface state in which crystal grains of the metal are sheared. That is, in the present embodiment, the first region R1 is a rolling surface, and the second region R2 is a cutting surface. In this way, the surface roughness of the first region R1 and the second region R2 can be easily adjusted by employing different processes in the first region R1 and the second region R2.
  • the first region R1 is provided at an end edge of the inner peripheral surface 301 of the flexible external gear 3 on the opening surface 35 side in the direction of the rotation axis Ax1 . That is, in the present embodiment, the flexible external gear 3 has a cylindrical shape having an opening surface 35 on one side in the tooth direction D1 of the external teeth 31 (here, the input side of the rotation axis Ax1).
  • the first region R1 is connected to the opening surface 35 . In this way, by providing the first region R1 at the end edge on the opening surface 35 side, when the wave generator 4 is fitted into the flexible external gear 3 from the opening surface 35 side, it is difficult for the wave generator 4 to catch on the flexible external gear 3.
  • the inner peripheral surface 301 of the situation is provided at an end edge of the inner peripheral surface 301 of the situation.
  • the first region R1 mainly has a smooth surface state in which crystal grains are not sheared.
  • the second region R2 mainly has a surface state in which crystal grains are sheared.
  • the "surface roughness” is a value obtained from the arithmetic mean roughness (Ra) in a direction (tooth direction D1 ) parallel to the rotation axis Ax1 .
  • the first region R1 when the unit length W1 (0.25 mm as an example) of the tooth direction D1 and the unit length Y1 (1 ⁇ m as an example) in the direction of longitudinal magnification are specified, the first region R1 The surface roughness is smaller than that of the second region R2.
  • the surface roughness of the first region R1 is preferably not less than 1/40 and not more than 1/10 of the surface roughness of the second region R2.
  • the surface roughness of the first region R1 is not limited to 1/40 times or more than the surface roughness of the second region R2, for example, it may be 1/80 times or more, 1/50 times or more, 1/30 times or more, or 1/20 times. above and so on.
  • the surface roughness of the first region R1 is not limited to 1/10 or less than the surface roughness of the second region R2, for example, it may be 1/2 or less, 1/5 or less, 1/16 or less, or 1/10 or less. / 20 times or less, etc.
  • the lubricant Lb1 tends to stay in the first region R1.
  • the surface roughness of the first region R1 is preferably not less than Ra0.01 and not more than Ra0.1, and in this case, it is preferably not more than 1/10 times the surface roughness (Ra) of the second region R2.
  • the second region R2 formed by performing processing such as cutting, grinding, or honing on the inner peripheral surface 301 of the flexible external gear 3 to shear the crystal grains of the metal structure a grain boundary is generated.
  • Scaly “burrs” (protrusions).
  • the first region R1 formed by subjecting the inner peripheral surface 301 of the flexible external gear 3 to the inner peripheral surface 301 such as rolling without shearing the crystal grains of the metal structure such scaly spots do not occur. "burrs” to achieve a smooth surface state.
  • the “surface roughness” is not limited to the arithmetic mean roughness (Ra) in the direction parallel to the rotation axis Ax1 (tooth direction D1).
  • “Surface roughness” can be, for example, the arithmetic average roughness (Ra) or the maximum height (Ry) of the flexible external gear 3 in the circumferential direction, the ten-point average roughness (Rz), the average interval of concavities and convexities (Sm), the local peak The average interval (S) or the load length rate (tp) and so on.
  • the lubricant Lb1 in order for the lubricant Lb1 to easily permeate the gap X1 between the flexible external gear 3 and the outer ring 421, it is preferable that at least the first region R1 of the inner peripheral surface 301 of the flexible external gear 3 and the outer peripheral surface of the outer ring 421 424 is not oil-resistant.
  • the rolling surface 300 (first rolling surface) which is not formed by shearing metal crystal grains (rolling process) is provided on the external teeth 31 . Therefore, as shown in FIG. 7 , the rolling surface 300 included in the external teeth 31 has a smooth surface state in which metal crystal grains are not sheared. Thereby, the friction between the external teeth 31 and the internal teeth 21 is reduced, the loss due to the friction between the external teeth 31 and the internal teeth 21 is reduced, and the power transmission efficiency of the harmonic gear device 1 is hardly lowered.
  • the rolling surface 300 is only provided on the outer teeth 31 among the outer teeth 31 and the inner teeth 21 .
  • the rolling surface 300 is at least provided on the outer teeth 31 , and the surface roughness is smaller than that of the inner teeth 21 .
  • the rolling surface 300 is a surface formed by processing (rolling processing) without shearing the crystal grains of the metal, so for example, the internal surface formed by processing the crystal grains of the metal like cutting, grinding, or honing. Compared with the teeth 21, the surface roughness of the rolling surface 300 is of course smaller. Furthermore, by providing the rolling surface 300 with such a smooth surface state on the external teeth 31 pressed against the internal teeth 21 of the rigid internal gear 2 like a wedge, the friction between the external teeth 31 and the internal teeth 21 is further reduced.
  • the rolling surface 300 is provided only on the external teeth 31 in the outer peripheral surface of (the body portion 321 of) the flexible external gear 3 . That is, the external teeth 31 are provided on the outer peripheral surface of the flexible external gear 3, and parts other than the external teeth 31 in the outer peripheral surface of the flexible external gear 3 are sheared by, for example, cutting, grinding or honing. Formed by grain processing. As a result, the rolling surface 300 of the external teeth 31 has a smaller surface roughness than a portion of the outer peripheral surface of the flexible external gear 3 other than the external teeth 31 . Thereby, only the required portion of the outer peripheral surface of the flexible external gear 3 can be rolled, which has the advantage of improving workability.
  • the rolling surface 300 is provided at a position other than the tooth tops 313 and 213 of at least one of the external teeth 31 and the internal teeth 21 . That is to say, as shown in FIG. 7, the external tooth 31 has a dedendum 312, a dedendum 313, and a middle portion 314 in the tooth height direction, and the rolling surface 300 of the external tooth 31 is provided at a position other than the dedendum 313 (the dedendum 313). 312 and middle portion 314 etc.).
  • the rolling surface 300 is only the dedendum 312 and the middle portion 314 in the tooth height direction on the surface of the external tooth 31, and the tooth top 313 is cut by cutting, grinding, or honing, for example. Formed by grain processing.
  • the surface roughness of the rolled surface 300 that is, the surface of the dedendum 312 and the middle portion 314 in the tooth height direction is smaller than that of the tooth top 313 which is not the rolled surface 300 . Therefore, the rolling surface 300 (the surface of the dedendum 312 and the middle portion 314 in the tooth height direction) corresponds to the first region R1 in the inner peripheral surface 301 of the flexible external gear 3 , not the tooth top 313 of the rolling surface 300 The surface of is equivalent to the second region R2.
  • the friction between the external teeth 31 and the internal teeth 21 can be easily reduced.
  • a gap G1 is ensured between the dedendum 313 of the external teeth 31 and the dedendum 212 of the internal teeth 21 .
  • the external teeth 31 are in contact with the internal teeth 21 at parts other than the tooth tops 313 (the dedendum 312 and the middle part 314, etc.). tooth 21 friction.
  • the rolling surface 300 includes a flank trimming portion 310 (see FIG. 1B ) provided at at least one end in the flank direction D1.
  • the “tooth profile trimming” mentioned in this disclosure refers to the trimming in the tooth profile direction D1, and the profile trimming portion 310 of the external tooth 31 is a part of the external tooth 31 where profile profile modification is performed.
  • flank modification it is possible to give an intentional bulge to the regular flank shape of the gear, or to change the helix angle.
  • Typical processing for tooth profile correction includes crown processing and relief processing (end undulation). The crowning is processing that rounds the center portion of the gear in the tooth direction D1 so that the center portion thereof is convex in the tooth direction D1.
  • Ripping machining is a machining method in which both ends in the tooth radial direction D1 are moderately avoided. Conveying is processing that extends over substantially the entire length in the radial direction D1 such that the center portion is rounded, whereas relief processing is processing that avoids only both ends in the radial direction D1. Whether it is crowning or undercutting, by making the tooth thickness at both ends in the tooth line direction D1 smaller than that in the center, the tooth contact position with the mating gear can be brought closer to the center in the tooth line direction D1.
  • FIG. 8A in which a part of the dedendum 312 of the external tooth 31 (area Z1 in FIG. 7 ) is enlarged, in the external tooth 31, the dedendum 312 and the middle part 314 where the rolling surface 300 is provided mainly become A smooth surface state where the grains are not sheared.
  • FIG. 8B which is an enlarged part of the tooth tip 313 of the external tooth 31 (region Z2 in FIG. 7 ), at the tooth tip 313 where the rolling surface 300 is not provided, the crystal grains are mainly sheared. surface condition.
  • the dedendum 312 roll The surface roughness of the pressing surface 300 is smaller than the surface roughness of the crest 313.
  • the surface roughness of the rolling surface 300 is preferably not less than 1/64 times and not more than 1/10 times the surface roughness of the crests 313 .
  • the surface roughness of the rolling surface 300 is not limited to 1/64 or more of the surface roughness of the crest 313, for example, it may be 1/80 or more, 1/50 or 1/30 or 1/16. above and so on.
  • the surface roughness of the rolling surface 300 is not limited to 1/10 or less of the surface roughness of the crest 313, for example, it may be 1/2 or less, 1/5 or less, 1/12 or less, or 1/10 or less. 16 times or less, etc.
  • the surface roughness of the rolling surface 300 (the dedendum 312 and the middle portion 314 ) is a value sufficiently smaller than the surface roughness of the tooth top 313 , so that the tooth root 312 and the middle portion 314 are easily reduced. 21 friction between.
  • the surface roughness of the rolling surface 300 is preferably not less than Ra 0.01 and not more than Ra 0.2, and in this case, it is preferably not more than 1/10 times the surface roughness (Ra) of the crest 313.
  • the surface hardness of the middle portion 314 in the tooth height direction of the external teeth 31 is at least higher than that of the tooth tips 313 .
  • only the middle portion 314 of the outer tooth 31 is locally heat-treated using a method such as laser hardening that enables local heat treatment, thereby locally increasing the surface hardness of the outer tooth 31 .
  • the surface hardness of the tooth tips 313 of the external teeth 31 is HRC40, and the surface hardness of the middle part 314 is about HRC60.
  • the harmonic gear unit 1 is used for a long period of time, for example, foreign matter such as metal powder or nitride may be generated due to chipping, abrasion, or the like due to contact between the internal teeth 21 and the external teeth 31 .
  • the surface hardness of the external teeth 31 is locally increased, thereby making it less likely to damage the toughness and maintain the stability of the flexible external gear 3 compared to the case where the surface hardness of the entire flexible external gear 3 is increased. Deformation tolerance.
  • the middle portion 314 in the tooth height direction which can actually come into contact with the internal teeth 21, of the external teeth 31 of the flexible external gear 3, by increasing the surface hardness, it is possible to suppress the occurrence of damage due to contact with the internal teeth 21. Generation of foreign matter such as metal powder or nitride caused by chipping or wear of the external teeth 31.
  • the surface hardness of the internal teeth 21 is lower than that of the external teeth 31 . That is, the hardness of the surface of the external teeth 31 is higher (harder) than the hardness of the surface of the internal teeth 21 .
  • the “hardness” mentioned in this disclosure refers to the degree of hardness of an object, and the hardness of a metal is represented by, for example, the size of a pit formed by pushing a steel ball with a certain pressure.
  • examples of the hardness of metals include Rockwell hardness (HRC), Brinell hardness (HB), Vickers hardness (HV), and Shore hardness (Hs).
  • HRC Rockwell hardness
  • HB Brinell hardness
  • HV Vickers hardness
  • Hs Shore hardness
  • the hardness is represented by Vickers hardness (HV).
  • As a means for increasing the hardness (hardening) of a metal member there are, for example, alloying or heat treatment.
  • the surface of the external teeth 31 of the flexible external gear 3 is made of a material with high hardness and high toughness (toughness), and the internal teeth 21 of the rigid internal gear 2 are made of a material with a hardness lower than that of the external teeth 31 .
  • a material obtained by heat-treating (quenching and tempering) nickel-chromium-molybdenum steel specified as "SNCM439" by Japanese Industrial Standards (JIS: Japanese Industrial Standards) is used for the external teeth 31 .
  • Spherical graphite cast iron specified as "FCD800-2” by Japanese Industrial Standards (JIS) is used for the internal teeth 21 .
  • the surface hardness of the internal teeth 21 which is relatively low in hardness compared with the external teeth 31 , is preferably HV350 or less.
  • the surface hardness of the internal teeth 21 is selected within the range of HV250 or more and less than HV350.
  • the lower limit of the surface hardness of the internal teeth 21 is not limited to HV250, and may be, for example, HV150, HV160, HV170, HV180, HV190, HV200, HV210, HV220, HV230, or HV240.
  • the upper limit of the surface hardness of the internal teeth 21 is not limited to HV350, and may be, for example, HV360, HV370, HV380, HV390, HV400, HV410, HV420, HV430, HV440, or HV450.
  • the surface hardness of the external teeth 31 which is relatively harder than the internal teeth 21 , is preferably HV380 or higher.
  • the surface hardness of the external teeth 31 is selected within the range of not less than HV380 and not more than HV450.
  • the lower limit of the surface hardness of the external teeth 31 is not limited to HV380, and may be, for example, HV280, HV290, HV300, HV310, HV320, HV330, HV340, HV350, HV360, or HV370.
  • the upper limit of the surface hardness of the internal teeth 21 is not limited to HV450, and may be, for example, HV460, HV470, HV480, HV490, HV500, HV510, HV520, HV530, HV540, or HV550.
  • the difference between the surface hardness of the internal teeth 21 and the surface hardness of the external teeth 31 is HV50 or more. That is, the surface hardness of the external teeth 31 is set to be higher than the surface hardness of the internal teeth 21 by HV50 or more. In short, for example, if the surface hardness of the internal teeth 21 is HV350, the surface hardness of the external teeth 31 is HV400 or more. In addition, if the surface hardness of the external teeth 31 is HV380, the surface hardness of the internal teeth 21 is HV330 or less.
  • the difference between the surface hardness of the internal teeth 21 and the surface hardness of the external teeth 31 is not limited to HV50 or greater, and may be, for example, HV20 or greater, HV30 or greater, or HV40 or greater. Furthermore, the difference between the surface hardness of the internal teeth 21 and the surface hardness of the external teeth 31 is preferably greater, for example, more preferably HV60 or higher, HV70 or higher, HV80 or higher, HV90 or higher, or HV100 or higher. If the difference between the surface hardness of the internal teeth 21 and the surface hardness of the external teeth 31 is HV100 or more, when the surface hardness of the internal teeth 21 is HV350, the surface hardness of the external teeth 31 is HV450 or more.
  • the surface hardness of the internal teeth 21 is set to be lower than the surface hardness of the external teeth 31 . Therefore, when the internal teeth 21 contact the external teeth 31 during the operation of the harmonic gear device 1 , the internal teeth 21 having a relatively low surface hardness wear more aggressively than the external teeth 31 . When the two members (the inner teeth 21 and the outer teeth 31 ) having different surface hardnesses contact each other, the wear of the relatively soft inner teeth 21 advances, thereby suppressing the wear of the relatively hard outer teeth 31 .
  • the harmonic gear unit 1 since the tooth surfaces of the internal teeth 21 are moderately worn, the real contact area between the internal teeth 21 and the external teeth 31 increases, and the surface pressure decreases, making it difficult to generate Wear of the external teeth 31 .
  • the surface hardness of the internal teeth 21 is HV350 or less as in the present embodiment, even if foreign matter is generated due to chipping or wear of the internal teeth 21 due to contact between the internal teeth 21 and the external teeth 31, the foreign matter is relatively small. Soft.
  • the surface hardness of the internal teeth 21 and the external teeth 31 does not have to be specified by Vickers hardness (HV), and can also be specified by other hardness, such as Rockwell hardness (HRC), Brinell hardness (HB) or Shore hardness (Hs).
  • HV Vickers hardness
  • HRC Rockwell hardness
  • HB Brinell hardness
  • Hs Shore hardness
  • the surface hardness of the internal teeth 21 is preferably HRC30 or less.
  • the surface hardness of the internal teeth 21 is selected within the range of HRC20 to less than HRC30.
  • the lower limit of the surface hardness of the internal teeth 21 is not limited to HRC20, and may be, for example, HRC10, HRC15, or HRC25.
  • the upper limit of the surface hardness of the internal teeth 21 is not limited to HRC30, and may be, for example, HRC35, HRC40, or HRC45.
  • the surface hardness of the external teeth 31 is preferably HRC40 or higher.
  • the surface hardness of the external teeth 31 is selected within the range of not less than HRC40 and not more than HRC60.
  • the lower limit of the surface hardness of the external teeth 31 is not limited to HRC40, and may be, for example, HRC30, HRC35, or the like.
  • the upper limit of the surface hardness of the external teeth 31 is not limited to HRC60, and may be, for example, HRC50, HRC55, HRC65, HRC70, or HRC75.
  • the harmonic gear device 1 of the present embodiment by providing the first region R1 with a small surface roughness on the back side of the external teeth 31 in the inner peripheral surface 301 of the flexible external gear 3, Accordingly, sufficient lubricant Lb1 is maintained at the contact portion between the flexible external gear 3 and the wave generator 4 . Therefore, the surface of the contact portion of the flexible external gear 3 with the bearing 42 (the outer ring 421 ) is covered with the lubricant Lb1, and the occurrence of fretting wear can be suppressed. Or the generation of foreign objects of sound quality coming out of the outer ring 421 .
  • the transmission efficiency of the harmonic gear device 1 is further improved. , extended life and improved performance.
  • the internal teeth 21 have a dedendum 212 and a dedendum 213 .
  • the internal teeth 21 are provided on the inner peripheral surface of the rigid internal gear 2, so the dedendum 212 of the internal teeth 21 corresponds to the inner peripheral surface of the rigid internal gear 2, and the addendum 213 faces inward from the inner peripheral surface of the rigid internal gear 2 (the rigid internal gear 2 center of gear 2) protrudes.
  • the external teeth 31 have a dedendum 312 and a dedendum 313 as shown in FIG. 1B .
  • the external teeth 31 are arranged on the outer peripheral surface of the flexible external gear 3 (the body part 321), so the dedendum 312 of the external teeth 31 is equivalent to the outer peripheral surface of the flexible external gear 3 (the body part 321), and the addendum 313 is from the flexible external gear 3 (the body part 321).
  • the outer peripheral surface of (the body part 321 of) the external gear 3 protrudes outward.
  • the crests 313 of the external teeth 31 are inserted between adjacent pairs of crests 213 of the internal teeth 21 , so that the internal teeth 21 and the external teeth 31 are meshed.
  • the dedendum 313 of the external tooth 31 is opposed to the dedendum 212 of the internal tooth 21
  • the dedendum 213 of the internal tooth 21 is opposed to the dedendum 312 of the external tooth 31 .
  • the internal teeth 21 have chamfered portions 211 at both end portions in the tooth direction D1.
  • the chamfered portion 211 is a C surface that reduces the amount of protrusion of the internal teeth 21 toward both sides in the tooth direction D1 , and is basically a portion that does not contribute to the meshing of the internal teeth 21 and the external teeth 31 . That is, the chamfered portion 211 of the internal tooth 21 does not contact the external tooth 31 at the position where the internal tooth 21 and the external tooth 31 mesh.
  • the external teeth 31 have chamfered portions 311 at both end portions in the tooth direction D1.
  • the chamfered portion 311 is a C surface that reduces the amount of protrusion of the internal teeth 21 toward both sides in the tooth direction D1 , and is basically a portion that does not contribute to the meshing of the internal teeth 21 and the external teeth 31 . That is to say, the chamfered portion 311 of the external tooth 31 is not in contact with the internal tooth 21 at the meshing position of the internal tooth 21 and the external tooth 31 .
  • the internal teeth 21 of the rigid internal gear 2 have tooth-shaft trimming portions 210 . That is, in the wave gear device 1 , at least the internal teeth 21 are shaped.
  • the tooth profile trimming portion 210 of the inner tooth 21 is disposed at least one end portion in the tooth profile direction D1.
  • the internal tooth 21 has a tooth profile trimming portion 210 at least one end portion of the internal tooth 21 in the tooth profile direction D1.
  • the flank trimming portions 210 are provided at both ends of the internal teeth 21 in the flank direction D1.
  • the external teeth 31 of the flexible external gear 3 also have tooth-shape correcting portions 310 . That is to say, the harmonic gear unit 1 implements profile correction not only on the internal teeth 21 but also on the external teeth 31 .
  • the flank trimming portion 210 of the external teeth is disposed at least one end portion in the flank direction D1.
  • the external teeth 31 have tooth profile trimming portions 310 at least one end portion of the external teeth 31 in the tooth profile direction D1.
  • the flank trimming portions 310 are provided at both ends of the external teeth 31 in the flank direction D1.
  • the wave gear device 1 of the present embodiment at least one of the inner teeth 21 and the outer teeth 31 has the tooth shape modification portions 210 , 310 .
  • the tooth shape trimming portions 210 and 310 make it difficult to generate stress concentration due to excessive tooth contact between the internal teeth 21 and the external teeth 31 , and as a result, the tooth contact between the internal teeth 21 and the external teeth 31 can be improved. Thereby, foreign matter caused by chipping or abrasion due to contact between the internal teeth 21 and the external teeth 31 is less likely to occur, and it is possible to realize the wave gear device 1 in which reliability is less likely to be lowered.
  • the contact portion between the flexible external gear 3 and the wave generator 4 will be damaged. Fretting wear may occur. In addition, if fretting wear occurs, roughness of the surface, rust caused by abrasive powder, and damage to the wave generator 4 (the bearing 42) caused by the ingress of abrasive powder into the wave generator 4, etc. may be caused. The reliability of the harmonic gear unit 1 is affected.
  • the cause of such fretting wear is considered to be "lubricant depletion" in which the lubricant Lb1 is insufficient or exhausted at the contact portion between the flexible external gear 3 and the wave generator 4 . That is, it is presumed that the contact portion between the flexible external gear 3 and the wave generator 4 is originally in an environment where fretting wear is likely to occur due to microvibration between the contact surfaces in a state where the lubricant Lb1 is insufficient. The following two reasons are specifically considered as reasons why such fretting wear is likely to occur in an environment.
  • the first reason is that the elastic deformation of the flexible external gear 3 is repeated frequently. That is, during one revolution of the cam 41 of the wave generator 4, the flexible external gear 3 repeats elastic deformation twice in one direction (for example, the up-down direction in FIG. 2A ) to have an elliptical major axis. Therefore, when the cam 41 rotates at a high speed, the flexible external gear 3 is elastically deformed repeatedly at high speed, and vibrations are likely to be generated at the contact portion between the flexible external gear 3 and the wave generator 4 as the elastic deformation is repeated. As a result, microvibration occurs in a state where the lubricant Lb1 is insufficient at the contact portion between the flexible external gear 3 and the wave generator 4 .
  • the end of the flexible external gear 3 on the opening surface 35 side in the direction of the rotation axis Ax1 is deformed more than the end on the bottom 322 side, Becomes a shape closer to an elliptical shape. Therefore, in the state where the flexible external gear 3 is elastically deformed, as shown in FIG. 302. Also, the inclination angle ⁇ 1 of the tapered surface 302 changes with elastic deformation of the flexible external gear 3 .
  • the inclination angle ⁇ 1 of the tapered surface 302 becomes the largest at both ends in the major axis direction of the ellipse ("major axis side” in FIG. 9 ).
  • the inclination angle ⁇ 1 of the tapered surface 302 is the smallest at both ends in the minor axis direction of the ellipse ("minor axis side” in FIG. 9). Therefore, the inclination angle ⁇ 1 of the tapered surface 302 also changes at a high speed due to the frequent and repeated elastic deformation of the flexible external gear 3, whereby the inner peripheral surface 301 (tapered surface 302) of the flexible external gear 3 repeatedly impacts the outer surface.
  • the outer peripheral surface 424 of the ring 421 vibrates in a manner. As described above, microvibrations accompanying impacts are generated, and as a result, fretting wear is likely to occur at the contact portion between the flexible external gear 3 and the wave generator 4.
  • the second reason is that the relative rotation between the outer ring 421 and the flexible external gear 3 is at a low speed. That is, due to the influence of the gap X1 between the outer ring 421 and the flexible external gear 3, the outer ring 421 and the flexible external gear 3 are elastically deformed as the cam 41 of the wave generator 4 rotates. There may be relative rotation with the flexible external gear 3 . However, this relative rotation is, for example, a low-speed rotation of about a few thousandths or a few hundredths of the rotation speed of the cam 41 .
  • the lubricant Lb1 cannot be expected to flow due to the relative rotation, and it is disadvantageous to form a film (oil film) of the lubricant Lb1 at the contact portion. environment of. Nevertheless, since the outer ring 421 and the flexible external gear 3 may be relatively rotated, the outer ring 421 and the flexible external gear 3 rub against each other, creating an environment where fretting wear is likely to occur.
  • the lubricant Lb1 can be forcibly supplied to the contact portion between the outer ring 421 and the flexible external gear 3 in an environment where fretting wear is likely to occur. . That is, the harmonic gear device 1 can supply the lubricant Lb1 to the contact portion of the flexible external gear 3 and the wave generator 4 through the through hole H1 , thereby maintaining sufficient lubricant Lb1 at the contact portion. In this way, occurrence of fretting wear is suppressed by preventing "lubricant depletion" in which the lubricant Lb1 is insufficient or exhausted at the contact portion between the outer ring 421 and the flexible external gear 3 .
  • the first region R1 located on the inner peripheral surface 301 of the flexible external gear 3 on the back side of the external teeth 31 is formed to have a surface roughness higher than that of the first region R1.
  • the second region R2 is small. Therefore, by making the inner peripheral surface 301 of the flexible external gear 3 a partially smooth surface like the first region R1, the lubricant Lb1 is likely to stay at the contact portion of the flexible external gear 3 with the wave generator 4. , sufficient lubricant Lb1 can be maintained at the contact site. Accordingly, it is possible to further prevent "lubricant depletion" in which the lubricant Lb1 is insufficient or exhausted at the contact portion between the outer ring 421 and the flexible external gear 3, and suppress the occurrence of fretting wear.
  • the harmonic gear device 1 of the present embodiment it is possible to provide a device in which troubles due to fretting wear between the outer ring 421 and the flexible external gear 3 are less likely to occur, and reliability degradation is less likely to occur. Harmonic gear unit 1. Furthermore, since the harmonic gear device 1 of the present embodiment is less prone to reliability degradation even when it is used for a long period of time, the transmission efficiency of the harmonic gear device 1 is improved, its life is extended, and its performance is improved.
  • the harmonic gear unit 1 supplies the lubricant Lb1 to the contact portion between the outer ring 421 and the flexible external gear 3, it is difficult to hinder the deformation followability of the flexible external gear 3, and it brings about improvement of power transmission efficiency and the improvement of power transmission efficiency based on application. Life extension due to reduction of load on the bearing 42 and the like. Furthermore, it is also possible to prevent the wear powder generated by fretting wear from entering the bearing 42, so the occurrence of damage originating from indentation (surface-originated spalling) due to the bite of wear powder can also be reduced. Therefore, life extension and performance improvement can be expected as the harmonic gear device 1 .
  • the lubricant Lb1 can also be supplied to the gap X1. That is, since the lubricant Lb1 supplemented between the outer ring 421 and the inner ring 422 is supplied to the gap X1 through the through hole H1, it is difficult to generate a “slip” at the contact portion with the flexible external gear 3 on the entire circumference of the outer ring 421. Lubricant exhausted".
  • the rolling elements 423 when the bearing 42 operates to rotate the plurality of rolling elements 423 , the rolling elements 423 function as a pump, whereby the lubricant Lb1 can be forcibly sent into the gap X1 through the through hole H1 . Further, the surface roughness of the first region R1 located on the back side of the external teeth 31 in the inner peripheral surface 301 of the flexible external gear 3 is formed small. According to these configurations, the lubricant Lb1 supplied to the gap X1 through the through hole H1 easily stays on the inner peripheral surface 301 of the flexible external gear 3 , and depletion of the lubricant in the gap X1 can be efficiently eliminated.
  • the elastic deformation of the flexible external gear 3 is repeated, and the rapid change of the inclination angle ⁇ 1 of the tapered surface 302 also contributes to the diffusion of the lubricant Lb1 in the gap X1. Furthermore, not only suppression of lubricant depletion but also improvement of startability of the harmonic gear device 1 in a low-temperature environment where the lubricant Lb1 is likely to solidify can be achieved, for example.
  • FIG. 10 is a cross-sectional view showing an example of a robot 9 employing the harmonic gear device 1 according to the present embodiment.
  • the robot 9 is a horizontal multi-joint robot, that is, a so-called SCARA (Selective Compliance Assembly Robot Arm) type robot.
  • SCARA Selective Compliance Assembly Robot Arm
  • the robot 9 includes two robot joint devices 130 (including the harmonic gear unit 1 ) and a link 91 .
  • the two robot joint devices 130 are respectively provided at two joints of the robot 9 .
  • the link 91 connects the two robot joint devices 130 .
  • the harmonic gear unit 1 is not a cup type, but a top hat type wave speed reduction device. That is, in the harmonic gear device 1 illustrated in FIG. 10 , the flexible external gear 3 formed in the shape of a hat is used.
  • FIG. 11 is a schematic explanatory view showing the process of machining the inner peripheral surface 301 of the flexible external gear 3 .
  • FIG. 12A is a schematic sectional view showing a rolling roll T1 and a chuck member T2 used for processing the inner peripheral surface 301 of the flexible external gear 3
  • FIG. 12B is a schematic side view thereof.
  • FIG. 13A is a schematic sectional view showing a chuck member T2 of a modified example
  • FIG. 13B is a schematic enlarged view of a region Z1 in FIG. 13A .
  • FIG. 14 is a schematic explanatory view showing the process of machining the external teeth 31 of the flexible external gear 3 .
  • FIG. 14 is a schematic explanatory view showing the process of machining the external teeth 31 of the flexible external gear 3 .
  • FIG. 15A is a schematic front view of a hob T3 used for machining the external teeth 31
  • FIG. 15B is a schematic side view thereof
  • Fig. 16A is a schematic front view showing a tool T4 used for machining the rolling surface 300 of the external tooth 31
  • Fig. 16B is a schematic side view thereof.
  • the manufacturing method of the harmonic gear device 1 includes a preparation step (step P11 ) and a plastic working step (step P13 ).
  • the preparation step is a step of preparing the base material 3A to be the base of the flexible external gear 3 .
  • the plastic working step is a step of forming the first region R1 on the inner peripheral surface 301 of the base material 3A by plastic working. That is, in this manufacturing method, an operator first prepares a cylindrical base material 3A having an inner peripheral surface 301 in a preparation step.
  • the inner peripheral surface 301 of the base material 3A is formed, for example, by cutting, grinding, or honing of a metal member. That is, the inner peripheral surface 301 of the base material 3A prepared in the preparation step is in a surface state in which metal crystal grains are sheared throughout the inner peripheral surface 301 like the second region R2 .
  • the operator performs plastic working on a part of the inner peripheral surface 301 of the base material 3A, so that the inner peripheral surface 301 includes the first region R1 (rolled surface) and the second region R2 (cutting surface).
  • the plastic working performed in the plastic working step is tumble processing using the rolling roll T1.
  • Rolling processing is a type of rolling processing in which a metal surface is flattened by a roll T12 (see FIG. 12A ) of the rolling roll T1 to form a smooth surface state.
  • the roller T12 made of a high-hardness metal is pressed against the inner peripheral surface 301 of the base material 3A, the roller T12 is rolled along the inner peripheral surface 301 along the inner surface.
  • the circumferential movement of the peripheral surface 301 plastically deforms the inner peripheral surface 301 to form the first region R1.
  • FIGS. 12A and 12B a rolling roll T1 as shown in FIGS. 12A and 12B is used in the plastic working step.
  • FIG. 12A corresponds to the cross section along line A1-A1 of FIG. 12B.
  • the rolling roll T1 has a main shaft portion T11 configured to be rotatable (rotatable) around a central axis Ax3, and a plurality of rolls T12 held on the outer peripheral portion of the main shaft portion T11.
  • a plurality of (here, eight as an example) rollers T12 are arranged at equal intervals in the circumferential direction of the main shaft portion T11.
  • Each roller T12 is formed in a cylindrical shape, and is held by the main shaft portion T11 in a rotatable state about a central axis Ax4 parallel to the central axis Ax3 (autorotation).
  • the central axis Ax4 rotates around the center (clockwise in the example of FIG. 12B ).
  • the plurality of rolls T12 in contact with the inner peripheral surface 301 of the base material 3A perform rolling while moving so as to roll on the inner peripheral surface 301 (step P13 of FIG. 11 ).
  • a plastic working step not only the first region R1 with a smooth surface state can be formed, but also surface modification such as improvement in wear resistance and improvement in fatigue strength can be expected.
  • step P12 there is also a chucking step (step P12 ) of chucking the base material 3A from the outer peripheral surface side with the chuck member T2 at least in the plastic working step. Accordingly, in a state where the roller T12 is pressed against the inner peripheral surface 301 of the base material 3A, the deformation of the base material 3A itself extending to the outer peripheral side can be suppressed, and the inner peripheral surface 301 can be rolled efficiently.
  • the chuck member T2 is formed in a cylindrical shape that is opened on both sides in a direction parallel to the central axis Ax3 as a whole.
  • the chuck member T2 has a body portion T21 integrally formed continuously in the circumferential direction and a plurality of individual pieces T22 divided into a plurality in the circumferential direction.
  • the plurality of individual pieces T22 are connected to one end edge (the right end edge in FIG. 12A ) of the main body portion T21 in the axial direction.
  • the inner diameter of the portion surrounded by the plurality of individual pieces T22 is reduced by bending the plurality of individual pieces T22 toward the central axis Ax3 with the connecting portion with the main body T21 as a fulcrum. Therefore, as shown in FIG. 11, the substrate 3A is inserted from the side of the plurality of individual pieces T22 in the chuck member T2 (process P11), and then the plurality of individual pieces T22 are tightened from the outside, and the chuck member T2 is removed from the outer peripheral side. Clip substrate 3A.
  • the external teeth 31 on the outer peripheral surface of the flexible external gear 3 are not formed in the plastic working step. That is, the base material 3A shown in FIG. 11 is in a state where the external teeth 31 are not formed.
  • the details of the process for forming the external teeth 31 will be described in the column of "(7.2) Processing of external teeth”. That is, the method of manufacturing the harmonic gear device 1 of the present embodiment further includes a step of forming the external teeth 31 on the outer peripheral surface of the base material 3A after the plastic working step. Accordingly, in the plastic working step of forming the first region R1 at the position on the back side of the external teeth 31 , troubles such as deformation of the external teeth 31 can be avoided.
  • the base material 3A may be subjected to surface treatment such as shot peening or chemical conversion film formation, for example.
  • surface treatment such as shot peening or chemical conversion film formation, for example.
  • the fatigue strength of the flexible external gear 3 can be improved by projecting small spherical shot material to modify and harden the surface.
  • the plastic working is performed by rotationally driving (the main shaft portion T11 of) the rolling roll T1, but it is not limited thereto, as long as there is a relative friction between the main shaft portion T11 of the rolling roll T1 and the base material 3A. Just rotate it.
  • plastic working may be performed by rotating the chuck member T2 while the main shaft portion T11 of the rolling roll T1 is fixed to rotate the substrate 3A relative to the main shaft portion T11 of the rolling roll T1 .
  • the chuck member T2 may have an inner peripheral surface T221 having a shape corresponding to the outer peripheral surface of the base material 3A.
  • the inner peripheral surfaces T221 of the plurality of individual pieces T22 of the chuck member T2 shown in FIGS. 13A and 13B are formed in a shape following the shape of the outer peripheral surface of the base material 3A before incising, that is, before the outer teeth 31 are formed.
  • an expansion portion 31A is provided on the outer peripheral surface of the base material 3A before tooth cutting and on the side of the opening surface 35 .
  • the swollen portion 31A is provided over the entire circumferential direction of the base material 3A, and is formed thicker than other portions.
  • the inner peripheral surface T221 of the plurality of individual pieces T22 has a recess having a shape corresponding to the swollen portion 31A, and the swelled portion 31A is fitted into the sag when the base material 3A is clamped by the chuck member T2.
  • the chuck member T2 has an inner peripheral surface T221 having a shape corresponding to the outer peripheral surface of the base material 3A, and is configured to be divisible into a plurality of individual pieces T22 in the circumferential direction. According to this configuration, in the plastic working step, the chuck member T2 can receive the rolling force from the rolling roll T1 over the entire area of the outer peripheral surface of the base material 3A. Therefore, for example, compressive residual stress due to rolling is also applied to the boundary portion between the body portion 321 of the flexible external gear 3 and the external teeth 31 .
  • the inner peripheral surface 301 is also formed of a rolling surface for the body part 321, so that at least the boundary part between the outer tooth 31 and the body part 321 can also be applied. Structure of compressive residual stress generated by rolling process.
  • the flexible external gear 3 is made thinner and the toughness is improved (increased allowable stress) under the action of compressive residual stress, so that the resistance to deformation of the flexible external gear 3 can be maintained.
  • the manufacturing method of the harmonic gear device 1 includes a step P21 , a step P22 , and a step P23 .
  • Step P21 is a step of preparing the (second) base material 3A to be the base of the flexible external gear 3 .
  • Step P22 is a step of forming the external teeth 31 on the (second) base material 3A.
  • Step P23 is a step of forming the rolling surface 300 on the external teeth 31 by plastic working. That is, in this manufacturing method, an operator first prepares the base material 3A having the swollen portion 31A in step P21.
  • the (second) base material 3A prepared in the step P21 is in a state in which the inner peripheral surface 301 is plastically worked (rolled) in the above-mentioned plastic working step to form the first region R1 .
  • the external teeth 31 are formed on the swollen portion 31A by, for example, cutting, grinding, or honing. That is, before the rolling surface 300 is formed in the step P23, the outer teeth 31 of the base material 3A are in a surface state in which metal crystal grains are sheared in the entire area of the outer teeth 31, similarly to the second region R2.
  • the manufacturing method since the (first) rolling surface 300 is formed on the outer teeth 31, the manufacturing method includes the above-mentioned steps P21 to P22 (see FIG. 14 ). 2)
  • the steps P21 to P23 are replaced as follows. That is, step P21 is a step of preparing the first base material to be the base of the rigid internal gear 2 .
  • step P22 is a step of forming the internal teeth 21 on the first base material.
  • Step P23 is a step of forming the rolling surface 200 by plastic working the internal teeth.
  • At least one of the step of forming the internal teeth 21 on the first base material and the step P22 of forming the external teeth 31 on the (second) base material 3A includes cutting.
  • the internal teeth 21 and the external teeth 31 are formed by gear cutting (hob processing) using a hob that rotationally drives the hob T3. That is, in the step P22 of forming the external teeth 31 on the base material 3A, as shown in FIG.
  • the hob T3 cuts the expanded portion 31A to form the external teeth 31 .
  • the base material 3A also rotates around the rotation axis Ax1 , whereby the external teeth 31 are formed over the entire circumference of the outer peripheral surface of the base material 3A.
  • hob T3 is used as shown in FIGS. 15A and 15B .
  • the hob T3 has a cylindrical portion T31 configured to be rotatable (rotatable) around the central axis Ax5, and a plurality of blades T32 protruding from the outer peripheral surface of the cylindrical portion T31.
  • the plurality of cutting edges T32 are arranged in a row so as to form a helical shape centering on the central axis Ax5.
  • the outline of a row (blade row) composed of a plurality of blades T32 is shown by a phantom line (two-dot chain line), and illustration of a part of the blades T32 is omitted.
  • the center axis Ax5 is used as the center axis Ax5 by the hob head.
  • the center (clockwise in the example of FIG. 15B ) rotationally drives the cylindrical portion T31.
  • the expansion portion 31A of the substrate 3A is cut by the cutting edge T32 of the hob T3, and the external teeth 31 are formed at the same pitch as the plurality of cutting edges T32 in the direction parallel to the central axis Ax5 (step P22 in FIG. 14 ). .
  • the external teeth 31 are formed, but the surface of the external teeth 31 is the same as the second region R2, and the entire region has a surface state in which metal crystal grains are sheared. . That is, scale-like scratches are generated on the surface of the outer teeth 31 corresponding to the feeding amount of the hob T3 or the like.
  • the rolling surface 300 is formed on the external teeth 31 by plastic working, thereby flattening the surface of the external teeth 31 with such irregularities as tool marks, thereby achieving smoothness. surface state.
  • the plastic working uses a tool T4 having ribs T42 having the same pitch as the hob T3 used for cutting, as shown in FIGS. 16A and 16B .
  • the tool T4 has a cylindrical portion T41 configured to be rotatable (rotatable) around the central axis Ax5, and a rib T42 protruding from the outer peripheral surface of the cylindrical portion T41.
  • the rib T42 is formed in a spiral shape centered on the central axis Ax5.
  • the cylindrical portion T41 has the same shape as the cylindrical portion T31 of the hob T3, and the rib T42 has the same shape as the outer shape of a row (blade row) composed of the plurality of blades T32 of the hob T3. That is, the tool T4 corresponds to a shape in which the blade portion T32 of the hob T3 is removed, and can be attached to the hob head instead of the hob T3.
  • the base material 3A is rotated around the rotation axis Ax1, and the center axis Ax5 is used as the center by the hob (in FIG. 16B, clockwise) to rotate and drive the cylindrical portion T41.
  • the surface of the external tooth 31 is plastically deformed in a state where the rib T42 of the tool T4 is in pressure contact with the external tooth 31 to form the rolling surface 300 (step P23 of FIG. 14 ).
  • the grain boundaries generated by the shearing of crystal grains are flattened together with the tool marks generated during tooth cutting, and the rolling surface 300 with a smooth surface state is realized.
  • the operator can easily form the rolling surface 300 on the outer teeth 31 by using the tool T4 instead of the hob T3 and only performing the same hob operation as in the hob machining.
  • the tool T4 forms the rolling surface 300 on the external tooth 31 by performing the same operation as the hob T3, machining such as crowning or tooth relief (end undulation) can be performed by rolling. Thereby, the rolling surface 300 including the flank trimming portion 310 can be easily realized.
  • a surface processing step of surface processing the outer ring 421 (in particular, the inner peripheral surface 425 serving as the rolling surface) is performed. That is, in order to prevent the through-hole H1 from becoming the origin of cracks in the outer ring 421 , it is preferable to leave a compressive residual stress around the through-hole H1 in the outer ring 421 . Therefore, it is preferable to form the through-hole H1 before performing a surface processing step such as quenching on the outer ring 421, and to leave the compressive residual stress generated by the heat treatment.
  • the fatigue strength of the outer ring 421 may be increased by performing shot peening in which a small spherical shot material is shot around the through hole H1 of the outer ring 421 to modify and harden the surface after the heat treatment.
  • the through hole H1 may be located at a position deviated from the center of the plurality of rolling elements 423 in a direction (tooth direction D1 ) parallel to the rotation axis Ax1 .
  • the through hole H1 is disposed at a position deviated from the center of the rolling element 423 toward the opening surface 35 , that is, at a position between the center of the rolling element 423 and the opening surface 35 in the tooth direction D1 .
  • the through-hole H1 may be provided in a plurality of places in a direction (tooth direction D1) parallel to the rotation axis Ax1.
  • the opening area of the through hole H1 on the side of the gap X1 may be smaller than the opening area on the side opposite to the gap X1. That is, in the (first) through hole H1 provided in the outer ring 421 , the opening area of the through hole H1 on the outer peripheral surface 424 side on the side of the gap X1 is larger than the opening area of the through hole H1 on the inner peripheral surface 425 side on the opposite side to the gap X1 .
  • the hole H1 has a small opening area. Thereby, the pressure of the lubricant Lb1 supplied to the gap X1 through the through-hole H1 can be increased.
  • FIGS. 17A and 17B show modified examples of the embodiment, and are cross-sectional views corresponding to FIGS. 1A and 1B .
  • (second) through holes H2 are provided in the external teeth 31 of the flexible external gear 3 .
  • the through-holes H2 include “second through-holes” provided in the external teeth 31 of the flexible external gear 3 .
  • the through hole H2 provided in the portion of the external teeth 31 of the flexible external gear 3 that is, the through hole H2 provided in a portion corresponding to the bearing 42 in the direction of the rotation axis Ax1 penetrates the flexible external gear 3 in the radial direction.
  • the opening surface on one side of the through hole H2 faces the gap X1 between the outer ring 421 and the flexible external gear 3
  • the opening surface on the other side of the through hole H2 faces the gap X1 between the external teeth 31 of the flexible external gear 3
  • the outer peripheral surface serving as the meshing surface with the internal teeth 21 is open. Therefore, one end of the through hole H2 is connected to the gap X1 between the outer ring 421 and the flexible external gear 3 , and the other end is connected to the space between the outer teeth 31 and the inner teeth 21 . Therefore, the space between the external teeth 31 and the internal teeth 21 communicates with the gap X1 between the outer ring 421 and the flexible external gear 3 via the through hole H2. Thereby, the lubricant Lb1 in the space between the external teeth 31 and the internal teeth 21 can be supplied to the gap X1 between the outer ring 421 and the flexible external gear 3 through the through-hole H2.
  • the external teeth 31 and the internal teeth 21 constitute a positive displacement pump such as a vane pump, and squeeze out the lubricant Lb1 to the gap X1 side with sufficient pressure, so that sufficient lubricant Lb1 can be easily supplied into the gap X1.
  • the (second) through hole H2 is located between the center and the end on the opening surface 35 side in the external teeth 31 in a direction parallel to the rotation axis Ax1 (tooth direction D1 ).
  • the (second) through-hole H2 is arranged at the dedendum 313 of the dedendum 312 and the dedendum 313 of the external teeth 31 .
  • the through holes H1 and H2 may be provided on both the outer ring 421 and the external teeth 31 of the flexible external gear 3 .
  • the lubricant Lb1 in the space between the outer ring 421 and the inner ring 422 of the bearing 42 can be supplied to the gap X1 between the outer ring 421 and the flexible external gear 3 through the through hole H1 .
  • the lubricant Lb1 in the space between the external teeth 31 and the internal teeth 21 can be supplied to the gap X1 between the outer ring 421 and the flexible external gear 3 through the through hole H2. Therefore, the lubricant Lb1 can be supplied to the gap X1 from both sides (inside and outside) in the radial direction.
  • the harmonic gear device 1 it is not an indispensable configuration of the harmonic gear device 1 to perform tooth profile modification on the internal teeth 21 and the external teeth 31 .
  • at least one of the internal teeth 21 and the external teeth 31 may not be subjected to profile modification.
  • the harmonic gear unit 1 it is not essential for the harmonic gear unit 1 to secure a distance equal to or greater than a predetermined value in the radial direction between the tracks of the plurality of rolling elements 423 and the opening surface of the (first) through-hole H1 provided in the outer ring 421 .
  • the rolling element 423 may close the through hole H1 without a gap between the opening surface of the through hole H1 and the rolling element 423 while the rolling element 423 is present at a position corresponding to the through hole H1 .
  • each rolling element 423 is supported at four points, and for example, each rolling element 423 may be supported at two points.
  • the harmonic gear unit 1 is not limited to the cup type described in the embodiment, and may be, for example, a top hat type, a ring type, a differential type, a flat type (pancake type), or a shield type.
  • a hat-shaped harmonic gear device 1 as illustrated in FIG. 10 has a cylindrical flexible external gear 3 having an opening surface 35 on one side in the tooth direction D1 as in the cup type. That is, the hat-shaped flexible external gear 3 has a flange portion at one end of the rotation axis Ax1 and has an opening surface 35 at an end opposite to the flange portion. Even the hat-shaped flexible external gear 3 has external teeth 31 at the end on the opening surface 35 side, and the wave generator 4 is fitted therein.
  • the structure of the actuator 100 is not limited to the structure described in the embodiment, and can be appropriately changed.
  • the connection structure between the input unit 103 and the cam 41 is not limited to a spline connection structure, and an Oldham coupling or the like may be used.
  • the Oldham coupling as the connection structure between the input part 103 and the cam 41, the eccentricity between the input side rotation axis Ax1 and the wave generator 4 (cam 41) can be canceled out, and the rigidity of the internal gear 2 and the flexibility can be further canceled out. Eccentricity of external gear 3.
  • the cam 41 may not be able to move along the rotation axis Ax1 relative to the input unit 103 .
  • the application examples of the harmonic gear device 1, the actuator 100, and the robot joint device 130 of this embodiment are not limited to the above-mentioned horizontal articulated robot, for example, industrial robots other than the horizontal articulated robot or Robots other than those for industrial use.
  • industrial robots other than the horizontal articulated robot include a vertical articulated robot, a parallel link robot, and the like.
  • robots other than industrial use include home-use robots, care-use robots, and medical-use robots.
  • the bearing 42 is not limited to a deep groove ball bearing, For example, an angular contact ball bearing etc. may be sufficient.
  • the bearing 42 is not limited to a ball bearing, and may be a roller bearing such as a cylindrical roller bearing, a needle roller bearing, or a tapered roller bearing in which the rolling elements 423 are not ball-shaped "rollers", for example. Even with the rolling elements 423 other than the ball shape (spherical body shape), a pressure difference is generated by the rotation of the rolling elements 423, and the rolling elements 423 function as a pump structure.
  • each component of the harmonic gear device 1 , the actuator 100 , or the robot joint device 130 is not limited to metal, and may be resin such as engineering plastic, for example.
  • the lubricant Lb1 is not limited to a liquid substance such as lubricating oil (oil), but may be a gel state substance such as grease.
  • the number and arrangement of the through-holes H1 are not limited to those described in the embodiment.
  • one, two, or four or more through holes H1 may be provided.
  • the interval P1 of the plurality of through-holes H1 may also be a multiple of the interval P2 of the plurality of rolling elements 423, and it is not essential that the plurality of through-holes H1 be arranged at equal intervals. of.
  • the rolling roll T1 and the chuck member T2 used for processing the inner peripheral surface 301 of the flexible external gear 3 are not limited to the above-mentioned configuration, and can be appropriately changed.
  • the hob T3 and the tool T4 used for the machining of the external teeth 31 are not limited to the above configurations, and can be appropriately changed.
  • the hob T3 and the tool T4 may be integrated so that the row (blade row) of the hob T3 consisting of a plurality of blades T32 is switched midway thereto to the rib T42 of the tool T4.
  • the harmonic gear device 1B of this embodiment is different from the harmonic gear device 1 of the above-mentioned embodiment in that the rolling surface 200 is provided on the internal teeth 21 of the rigid internal gear 2 .
  • the same reference numerals are assigned to the same configurations as those in Embodiment 1, and descriptions thereof are appropriately omitted.
  • Fig. 18A is an enlarged schematic view of the area Z1 in Fig. 2B.
  • 18B is a schematic view showing the surface state of the internal teeth 21 in the zone Z1 of FIG. 18A
  • FIG. 18C is a schematic view showing the surface state of the internal teeth 21 in the zone Z2 of FIG. 18A .
  • the rolling surface 200 is provided only on the inner teeth 21 among the outer teeth 31 and the inner teeth 21 .
  • the rolling surface 200 is a “second rolling surface” provided on the internal teeth 21 of the rigid internal gear 2 .
  • the (second) rolling surface 200 is also formed by processing (rolling processing) without shearing metal crystal grains, similarly to the (first) rolling surface 300 of the above-mentioned embodiment.
  • the rolling surface 200 (second rolling surface) provided on the internal teeth 21, it is also the same as the rolling surface 300 (first rolling surface) of the external teeth 31, and it is preferable that the parts other than the addendum 213 ( tooth root 212, etc.) is provided with a rolling surface 300. That is, as shown in FIG. 18B , which enlarges a part of the dedendum 212 of the internal tooth 21 (area Z1 in FIG. 18A ), the dedendum 212 and the like where the rolling surface 200 is provided in the internal tooth 21 mainly become A smooth surface state where the grains are not sheared. On the other hand, as shown in FIG.
  • the rolling surfaces 200 and 300 are provided on both the internal teeth 21 and the external teeth 31 .
  • the harmonic gear unit (1, 1A, 1B) of the first aspect includes a rigid internal gear (2), a flexible external gear (3), and a wave generator (4).
  • the rigid internal gear (2) is an annular member having internal teeth (21).
  • the flexible external gear (3) is an annular member having external teeth (31) and arranged inside the rigid internal gear (2).
  • the wave generator (4) has: a non-circular cam (41) driven to rotate about a rotating shaft (Ax1); and a bearing (42) attached to the outside of the cam (41).
  • the wave generator (4) is arranged inside the flexible external gear (3), and causes the flexible external gear (3) to bend.
  • the harmonic gear device (1, 1A, 1B) deforms the flexible external gear (3) along with the rotation of the cam (41), so that a part of the external teeth (31) meshes with a part of the internal teeth (21), thereby making The flexible external gear (3) rotates relative to the rigid internal gear (2) according to the difference in the number of teeth of the rigid internal gear (2).
  • At least one of the external teeth (31) and the internal teeth (21) includes a rolling surface (300, 200).
  • the rolling surface (300, 200) is provided on at least one of the external teeth (31) and the internal teeth (21).
  • the rolling surface (300, 200) includes an end portion provided on at least one side in the tooth direction (D1) The gear trimming part (310, 210).
  • the stress concentration at the end (tooth width end) in the tooth radial direction ( D1 ) is relieved, and the tooth contact is improved.
  • the rolling surface (300) is provided at least on the external teeth (31), and the rolling surface The surface roughness of the inner tooth (21) is smaller.
  • the rolling surface (300) is provided only on the outer peripheral surface of the flexible external gear (3) The outer teeth (31) in the.
  • a method for manufacturing a harmonic gear device (1, 1A, 1B) according to a sixth aspect is a method for manufacturing a harmonic gear device (1, 1A, 1B) according to any one of the first to fifth aspects, comprising: preparing for The process of preparing the first base material for the base of the rigid internal gear (2); the process of preparing the second base material (3A) for the base of the flexible external gear (3); the process of forming the internal teeth (21) on the first base material Steps; a step of forming external teeth (31) on the second base material (3A); and a step of forming rolling surfaces (300, 200) on at least one of the outer teeth (31) and the inner teeth (21) by plastic working.
  • the step of forming the inner teeth (21) on the first base material and the step of forming the outer teeth on the second base material (3A) At least one of the processes for the teeth (31) includes cutting.
  • the time required for forming the internal teeth (21) and the external teeth (31) can be shortened.
  • the plastic working uses a tool having ribs (T42) at the same pitch as the hob (T3) used for cutting (T4) to proceed.
  • the rolling surface (300, 200) can be easily formed by using the tool (T4) instead of the hob (T3) and only performing the same hob disk operation as hob processing.
  • a joint device (130) for a robot of a ninth aspect includes: the harmonic gear device (1, 1A, 1B) of any one of the first to fifth aspects; a first member (131) fixed to the rigid internal gear (2) and a second member (132) fixed to the flexible external gear (3).
  • the gear member of the tenth aspect is used as the rigid internal gear (2) or the flexible external gear (3) of the harmonic gear device (1, 1A, 1B) of any one of the first to fifth aspects.
  • the structures of the second to fifth aspects are not indispensable to the harmonic gear device (1, 1A, 1B), and can be appropriately omitted.
  • the configuration of the seventh or eighth aspect is not essential to the method of manufacturing the harmonic gear device (1, 1A, 1B), and can be appropriately omitted.
  • a harmonic gear device it is possible to provide a harmonic gear device, a method of manufacturing a harmonic gear device, a joint device for a robot, and a gear component that are less likely to cause a drop in power transmission efficiency.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Robotics (AREA)
  • Retarders (AREA)
  • Gear Processing (AREA)
  • Manipulator (AREA)
  • Gears, Cams (AREA)

Abstract

一种谐波齿轮装置。谐波齿轮装置包括刚性内齿轮(2)、挠性外齿轮(3)和波发生器(4)。波发生器具有以旋转轴为中心被旋转驱动的非圆形状的凸轮(41)、和装配于凸轮的外侧的轴承(42)。谐波齿轮装置伴随着凸轮的旋转而使挠性外齿轮(3)变形，使外齿(31)的一部分与内齿(21)的一部分啮合，从而使挠性外齿轮(3)按照与刚性内齿轮(2)的齿数差而相对于刚性内齿轮(2)进行相对旋转。外齿(31)与内齿(21)的至少一者包含滚压面(300)。以及该谐波齿轮装置的制造方法、含有该谐波齿轮装置的机器人用关节装置、用于该谐波齿轮装置的齿轮部件。

Description

谐波齿轮装置、谐波齿轮装置的制造方法、机器人用关节装置和齿轮部件
相关申请的交叉引用
本申请基于申请号为特愿2021-174097、申请日为2021年10月25日的日本专利申请提出，并要求该日本专利申请的优先权，该日本专利申请的全部内容在此引入本申请作为参考。
技术领域
本公开一般涉及谐波齿轮装置、谐波齿轮装置的制造方法、机器人用关节装置和齿轮部件，更详细地说，涉及包括刚性内齿轮、挠性外齿轮和波发生器的谐波齿轮装置、谐波齿轮装置的制造方法、机器人用关节装置和齿轮部件。
背景技术
在专利文献1中公开了通过渗氮处理进行谐波齿轮装置(挠曲啮合式齿轮装置)中的挠性外齿轮的表面处理。
谐波齿轮装置具有：环状的刚性内齿轮；配置于其内侧的杯形的挠性外齿轮；和嵌入其内侧的椭圆形的波发生器。挠性外齿轮包括圆筒状的躯体部和形成于躯体部的外周面的外齿。挠性外齿轮通过波发生器而挠曲为椭圆形，位于该椭圆形状的长轴方向的两端的外齿的部分与形成于刚性内齿轮的内周面的内齿啮合。
当波发生器通过电动机等旋转时，两齿轮的啮合位置沿圆周方向移动，在两齿轮之间产生与内齿和外齿的齿数差(2N(N为正整数))相应的相对旋转。此处，当刚性内齿轮一侧被固定时，能够从挠性外齿轮一侧得到与 两齿轮的齿数差相应地被大幅减速了的旋转输出。
现有技术文献
专利文献
专利文献1：日本特开2001-59153号公报
发明内容
发明所要解决的技术问题
但是，在上述那样的谐波齿轮装置中，位于挠曲为椭圆形的挠性外齿轮的长轴方向的两端的外齿如楔子那样推压刚性内齿轮的内齿，由此外齿与内齿啮合而得到旋转输出。因此，特别是在外齿与内齿的接触部位处，在外齿被推压至内齿的状态下，外齿与内齿相互摩擦。因此，在外齿与内齿的接触部位，产生因磨损而引起的损失，会导致表面的粗糙、因磨损粉而引起的生锈以及因磨损粉进入波发生器的内侧而引起的波发生器(的轴承)的损伤等，谐波齿轮装置的动力传递效率有可能下降。
本公开正是鉴于上述事由而作出的，其目的在于提供一种难以产生动力传递效率下降的谐波齿轮装置、谐波齿轮装置的制造方法、机器人用关节装置和齿轮部件。
用于解决技术问题的方案
本公开的一方式的谐波齿轮装置包括刚性内齿轮、挠性外齿轮和波发生器。所述刚性内齿轮是具有内齿的环状的部件。所述挠性外齿轮是具有外齿且配置于所述刚性内齿轮的内侧的环状的部件。所述波发生器具有以旋转轴为中心被旋转驱动的非圆形状的凸轮、和装配于所述凸轮的外侧的轴承。所述波发生器配置于挠性外齿轮的内侧，并使所述挠性外齿轮产生挠曲。所述谐波齿轮装置伴随着所述凸轮的旋转而使所述挠性外齿轮变形，使所述外齿的一部分与所述内齿的一部分啮合，从而使所述挠性外齿轮按照与所述刚性内齿轮的齿数差而相对于所述刚性内齿轮进行相对旋转。所 述外齿与所述内齿的至少一者包含滚压面。
本公开的一方式的谐波齿轮装置的制造方法具有：准备成为所述刚性内齿轮的基础的第一基材的工序；准备成为所述挠性外齿轮的基础的第二基材的工序；在所述第一基材形成所述内齿的工序；在所述第二基材形成所述外齿的工序；和在所述外齿和所述内齿的至少一者通过塑性加工形成所述滚压面的工序。
本公开的一方式的机器人用关节装置包括：所述谐波齿轮装置；第一构件，固定于所述刚性内齿轮；和第二构件，固定于所述挠性外齿轮。
本公开的一方式的齿轮部件用作所述谐波齿轮装置的所述刚性内齿轮或所述挠性外齿轮。
发明效果
根据本公开，具有以下优点：能够提供一种难以产生动力传递效率下降的谐波齿轮装置、谐波齿轮装置的制造方法、机器人用关节装置和齿轮部件。
附图说明
图1A是示出实施方式的谐波齿轮装置的概略结构的剖视图。
图1B是图1A的区域Z1的放大图。
图2A是从旋转轴的输入侧观察到的上述谐波齿轮装置的概略图。
图2B是图2A的区域Z1的放大图。
图3A是从旋转轴的输出侧观察到的上述谐波齿轮装置的概略的分解立体图。
图3B是从旋转轴的输入侧观察到的上述谐波齿轮装置的概略的分解立体图。
图4是示出包含上述谐波齿轮装置的致动器的概略结构的剖视图。
图5是对相当于图1B的范围放大主要部分而得的概略剖视图。
图6A是表示图5的区域Z1中的挠性外齿轮的内周面的表面状态的概略图。
图6B是表示图5的区域Z2中的挠性外齿轮的内周面的表面状态的概略图。
图7是图2B的区域Z1的放大概略图。
图8A是表示图7的区域Z1中的外齿的表面状态的概略图。
图8B是表示图7的区域Z2中的外齿的表面状态的概略图。
图9是用于示出上述谐波齿轮装置的渐缩面的长轴侧和短轴侧的动作的概念性说明图。
图10是示出使用了上述谐波齿轮装置的机器人的一例的剖视图。
图11是示出上述谐波齿轮装置的挠性外齿轮的内周面的加工的工序的概略说明图。
图12A是示出上述谐波齿轮装置的挠性外齿轮的内周面的加工所使用的滚压辊和卡盘构件的概略剖视图。
图12B是示出上述谐波齿轮装置的挠性外齿轮的内周面的加工所使用的滚压辊和卡盘构件的概略侧视图。
图13A是示出变形例的卡盘构件的概略剖视图。
图13B是图13A的区域Z1的概略放大图。
图14是示出上述谐波齿轮装置的挠性外齿轮的外齿的加工的工序的概略说明图。
图15A是示出上述谐波齿轮装置的挠性外齿轮的外齿的加工所使用的滚刀的概略剖视图。
图15B是示出上述谐波齿轮装置的挠性外齿轮的外齿的加工所使用的滚刀的概略侧视图。
图16A是示出上述谐波齿轮装置的挠性外齿轮的外齿的加工所使用的工具的概略剖视图。
图16B是示出上述谐波齿轮装置的挠性外齿轮的外齿的加工所使用的工具的概略侧视图。
图17A是示出实施方式的变形例的谐波齿轮装置的概略结构的剖视图。
图17B是图17A的区域Z1的放大图。
图18A是示出实施方式的谐波齿轮装置的主要部分的概略图。
图18B是表示图18A的区域Z1中的内齿的表面状态的概略图。
图18C是表示图18B的区域Z2中的内齿的表面状态的概略图。
具体实施方式
(1)概要
以下，对于本实施方式所涉及的谐波齿轮装置1的概要，参照图1A～图5进行说明。本公开中所参照的附图均为示意图，图中的各结构要素的大小和厚度各自的比不一定限于反映实际的尺寸比。例如，图2A～图3B中的、内齿21和外齿31的齿形、尺寸和齿数等均仅是为了说明而示意性地表示，并非限定于图示的形状的意思。
本实施方式所涉及的谐波齿轮装置1是包括刚性内齿轮2、挠性外齿轮3和波发生器4的齿轮装置。该谐波齿轮装置1中，在环状的刚性内齿轮2的内侧配置有环状的挠性外齿轮3，进一步在挠性外齿轮3的内侧配置有波发生器4。波发生器4通过使挠性外齿轮3挠曲为非圆形状，从而使挠性外齿轮3的外齿31与刚性内齿轮2的内齿21局部性地啮合。当波发生器4旋转时，内齿21与外齿31的啮合位置沿刚性内齿轮2的圆周方向移动，并在两齿轮(刚性内齿轮2和挠性外齿轮3)之间产生使挠性外齿轮3按照与刚性内齿轮2的齿数差进行的相对旋转。此处，如果刚性内齿轮2被固定，则挠性外齿轮3伴随着两齿轮的相对旋转而旋转。其结果是，可从挠性外齿轮3获得与两齿轮的齿数差相应地以比较高的减速比减速了的旋转输出。
另外，使挠性外齿轮3产生挠曲的波发生器4具有以输入侧的旋转轴Ax1(参照图1A)为中心被旋转驱动的非圆形状的凸轮41、和轴承42。轴承42配置于凸轮41的外周面411与挠性外齿轮3的内周面301之间。轴承42的内圈422固定于凸轮41的外周面411，轴承42的外圈421经由滚珠状的滚动体423被凸轮41按压而产生弹性变形。此处，由于通过滚动体423滚动，外圈421能够相对于内圈422相对旋转，因此当非圆形状的凸轮41旋转时，内圈422的旋转不传递至外圈421，而是在被凸轮41按压的挠性外齿轮3的外齿31发生谐波运动。由于发生外齿31的谐波运动，所以如上所述内齿21与外齿31的啮合位置沿刚性内齿轮2的圆周方向移动，从而使挠性外齿轮3产生与刚性内齿轮2之间的相对旋转。
总之，在这种谐波齿轮装置1中，具有轴承42的波发生器4一边使挠性外齿轮3挠曲一边实现通过内齿21与外齿31的啮合而进行的动力传递。
在这种谐波齿轮装置1中，特别是如果长期使用，则伴随着嵌入挠性外齿轮3的内侧的波发生器4的旋转，在挠性外齿轮3与波发生器4的接触部位可能产生微动磨损(fretting wear)。若产生微动磨损，则导致表面的粗糙、因磨损粉而引起的生锈以及因磨损粉进入波发生器4的内侧而引起的波发生器4(的轴承42)的损伤等，可能影响谐波齿轮装置1的可靠性。
作为一例，若由于表面的粗糙或者生锈而阻碍挠性外齿轮3的变形追随性，则波发生器4的旋转需要额外的能量，从而导致动力传递效率的下降或者因施加于轴承42的负载增加而引起的寿命缩短等。另外，当磨损粉进入轴承42时，以磨损粉向轴承42的外圈421或内圈422与滚动体423之间的咬入而产生的压痕为起源，外圈421、内圈422和滚动体423的任一者的表面都可能产生损伤。这样的损伤(表面起源型的剥落)导致谐波齿轮装置1的品质和特性等的恶化，因此结果会导致谐波齿轮装置1的可靠性的下降。因此，本实施方式的谐波齿轮装置1通过以下的结构抑制微动 磨损的产生，难以产生可靠性的下降。
即，如图1A～图3B所示，本实施方式的谐波齿轮装置1包括具有内齿21的环状的刚性内齿轮2、具有外齿31的环状的挠性外齿轮3和波发生器4。挠性外齿轮3配置于刚性内齿轮2的内侧。波发生器4配置于挠性外齿轮3的内侧，并使挠性外齿轮3产生挠曲。波发生器4具有：非圆形的凸轮41，以旋转轴Ax1为中心被旋转驱动；和轴承42，装配于凸轮41的外侧。谐波齿轮装置1伴随着凸轮41的旋转而使挠性外齿轮3变形，使外齿31的一部分与内齿21的一部分啮合，从而使挠性外齿轮3按照与刚性内齿轮2的齿数差而相对于刚性内齿轮2进行相对旋转。此处，如图5所示，挠性外齿轮3的内周面301中的位于外齿31的背侧的第一区域R1与除第一区域R1以外的第二区域R2相比表面粗糙度小。
根据该方式，挠性外齿轮3中的与轴承42的接触部位成为容易维持被润滑剂Lb1(参照图4)覆盖的状态的表面状态。总之，在挠性外齿轮3的内周面301中的、供轴承42推压的外齿31的背侧部位设有表面粗糙度比其他的表面粗糙度小的第一区域R1，因此该部位容易维持被润滑剂Lb1覆盖的状态。
也就是说，本实施方式的谐波齿轮装置1通过防止在外圈421与挠性外齿轮3的接触部位处润滑剂Lb1不足或枯竭的“润滑剂耗尽”，来抑制微动磨损的发生。进一步而言，通过将表面粗糙度比第二区域R2小的第一区域R1设于挠性外齿轮3的内周面301中的外齿31的背侧，从而在挠性外齿轮3与波发生器4的接触部位维持充分的润滑剂Lb1。其结果，挠性外齿轮3中的与轴承42(的外圈421)的接触部位的表面成为被润滑剂Lb1覆盖的状态，微动磨损的发生得以抑制。由此，在本实施方式的谐波齿轮装置1中，难以产生因轴承42(的外圈421)与挠性外齿轮3之间的微动磨损而引起的不良情况，能够提供难以产生可靠性下降的谐波齿轮装置1。并且，本实施方式的谐波齿轮装置1即使在长期使用之际也难以产生可靠 性的下降，因此还带来了谐波齿轮装置1的传递效率的改善、寿命延长和性能提高。
另外，在这种谐波齿轮装置1中，位于挠曲为椭圆形(非圆形状)的挠性外齿轮3的长轴方向的两端的外齿31如楔子那样推压刚性内齿轮2的内齿21，由此外齿31与内齿21啮合而得到旋转输出。因此，特别是在外齿31与内齿21的接触部位处，在外齿31被推压至内齿21的状态下，外齿31与内齿21相互摩擦。因此，在外齿31与内齿21的接触部位会产生因摩擦而引起的损失，导致表面的粗糙、因磨损粉而引起的生锈以及因磨损粉进入波发生器4的内侧而引起的波发生器4的损伤等，可能影响谐波齿轮装置1的可靠性。
即，若因外齿31与内齿21的摩擦而引起的损失、或者表面的粗糙或是生锈的产生而阻碍挠性外齿轮3的变形追随性，则波发生器4的旋转需要额外的能量，从而导致动力传递效率的下降。因此，本实施方式的谐波齿轮装置1通过以下结构，减少外齿31与内齿21的摩擦，由此难以产生动力传递效率的下降。
如图2B所示，在本实施方式的谐波齿轮装置1中，外齿31与内齿21的至少一者包含滚压面300。滚压面300不是通过切削加工那样剪切金属的晶粒的加工形成的，而是通过不剪切金属的晶粒的加工(滚压加工)而形成的。因此，外齿31与内齿21的至少一者所包含的滚压面300成为金属的晶粒没有被剪切的、平滑的表面状态。
根据该状态，由于外齿31与内齿21的摩擦减少，因此因外齿31与内齿21的摩擦而引起的损失减少，从而难以产生谐波齿轮装置1的动力传递效率的下降。另外，由于抑制因摩擦引起的表面的粗糙、又或是生锈，因此也难以阻碍挠性外齿轮3的变形追随性，波发生器4的旋转不容易需要额外的能量，从而抑制动力传递效率的下降。结果是，能够提供难以产生动力传递效率的下降的谐波齿轮装置1。
滚压面300只要设于外齿31与内齿21的至少一者即可。在本公开中，在区分分别设于外齿31与内齿21的滚压面的情况下，将设于外齿31的滚压面300称为“第一滚压面”，将设于内齿21的滚压面200(参照图18A)称为“第二滚压面”。在本实施方式中，作为一例，滚压面300仅设于外齿31与内齿21中的外齿31。换言之，在本实施方式中，滚压面300包含设于外齿31的“第一滚压面”。另一方面，关于内齿21侧的滚压面(第二滚压面)将在其他实施方式说明。
另外，如图4所示，本实施方式所涉及的谐波齿轮装置1与驱动源101和输出部102一起构成致动器100。换言之，本实施方式的致动器100包括谐波齿轮装置1、驱动源101和输出部102。驱动源101使波发生器4旋转。输出部102将刚性内齿轮2和挠性外齿轮3的任一者的旋转力作为输出取出。
另外，如图4所示，本实施方式的谐波齿轮装置1与第一构件131和第二构件132一起构成机器人用关节装置130。换言之，本实施方式的机器人用关节装置130包括谐波齿轮装置1、第一构件131和第二构件132。第一构件131固定于刚性内齿轮2。第二构件132固定于挠性外齿轮3。由此，在谐波齿轮装置1中，挠性外齿轮3产生与刚性内齿轮2之间的相对旋转，由此机器人用关节装置130中的第一构件131与第二构件132进行相对旋转。
根据本实施方式的机器人用关节装置130，具有难以产生谐波齿轮装置1的可靠性下降的优点。另外，根据本实施方式的机器人用关节装置130，具有难以产生动力传递效率下降的优点。
(2)定义
本公开中所说的“环状”是指至少在俯视时在内侧形成包围而成的空间(区域)的圈(环)那样的形状，并不限于在俯视时为正圆的圆形状(圆环状)，例如也可以是椭圆形状和多边形状等。进一步，例如也可以是如 杯状的挠性外齿轮3那样具有底部322之类的形状，若其躯体部321为环状，则称为“环状”的挠性外齿轮3。
本公开中所提及的“刚性”是指在对物体施加外力而物体要变形时，物体抵抗该变形的性质。换言之，拥有刚性的物体即使施加外力也难以变形。另外，本公开中所提及的“挠性”是指在对物体施加外力时，物体发生弹性变形(挠曲)的性质。换言之，拥有挠性的物体在被施加外力时容易发生弹性变形。因此，“刚性”和“挠性”是相反的意思。
特别在本公开中，刚性内齿轮2的“刚性”和挠性外齿轮3的“挠性”按相对的意思来使用。即，刚性内齿轮2的“刚性”是指至少与挠性外齿轮3相比，刚性内齿轮2拥有相对高的刚性，也就是说即使对刚性内齿轮2施加外力也难以变形。同样，挠性外齿轮3的“挠性”是指至少与刚性内齿轮2相比，挠性外齿轮3具有相对高的挠性，也就是说挠性外齿轮3在被施加外力时容易弹性变形。
另外，在本公开中，有时将旋转轴Ax1的一方侧(图1A的右侧)称为“输入侧”，并将旋转轴Ax1的另一侧(图1A的左侧)称为“输出侧”。也就是说，在图1A的例子中，挠性外齿轮3在旋转轴Ax1的“输入侧”具有开口面35。但是，“输入侧”和“输出侧”只不过是为了说明而赋予的标签，并非限定从谐波齿轮装置1观察到的输入和输出的位置关系的意思。
本公开中所提及的“非圆形状”是指不是正圆的形状，例如包含椭圆形状和长圆形状等。作为本实施方式中的一例，波发生器4的非圆形状的凸轮41为椭圆形状。也就是说，在本实施方式中，波发生器4使挠性外齿轮3挠曲为椭圆形状。
在本公开中所说的“椭圆形状”是指正圆被压扁而使彼此正交的长轴与短轴的交点位于中心这样的形状全体，并不限于由与一个平面上的某两定点的距离之和为恒定的点的集合构成的曲线即数学上的“椭圆”。也就 是说，本实施方式中的凸轮41既可以是如数学上的“椭圆”那样由与一个平面上的某两定点的距离之和为恒定的点的集合构成的曲线状，也可以不是数学上的“椭圆”而是像长圆那样的椭圆形状。如上所述，本公开中所参照的附图均为示意图，图中的各结构要素的大小和厚度各自的比不一定限于反映实际的尺寸比。因此，例如在图2A中，将波发生器4的凸轮41的形状设为稍大的椭圆形状，但是并无限定实际的凸轮41的形状的意思。
在本公开中所说的“旋转轴”是指成为旋转体的旋转运动的中心的虚拟的轴(直线)。也就是说，旋转轴Ax1是不伴有实体的虚拟轴。波发生器4以旋转轴Ax1为中心进行旋转运动。
在本公开中所说的“内齿”和“外齿”分别是指多个“齿”的集合(组)而不是单体的“齿”。也就是说，刚性内齿轮2的内齿21由形成于刚性内齿轮2的内周面的多个齿的集合构成。同样，挠性外齿轮3的外齿31由形成于挠性外齿轮3的外周面的多个齿的集合构成。
在本公开中所说的“平行”是指只要是一平面上的两条直线延长至任何位置都不相交的情况，也就是说除二者间的角度严格为0度(或180度)的情况之外，二者间的角度处于相对于0度收敛在几度(例如小于10度)左右的误差范围的关系。同样，本公开所说的“正交”是指除二者间的角度严格地以90度相交的情况之外，二者间的角度相对于90度收敛在几度(例如小于10度)左右的误差范围的关系。
(3)构成
以下，参照图1A～图4来说明本实施方式的谐波齿轮装置1、致动器100和机器人用关节装置130的详细结构。
图1A是示出谐波齿轮装置1的概略结构的剖视图，图1B是图1A的区域Z1的放大图。图2A是从旋转轴Ax1的输入侧(图1A的右侧)观察到的谐波齿轮装置1的概略图，图2B是图2A的区域Z1的放大图。图3A从旋转轴Ax1的输出侧(图1A的左侧)观察到的、谐波齿轮装置1的概 略的分解立体图。图3B是从旋转轴Ax1的输入侧观察到的、谐波齿轮装置1的概略的分解立体图。图4是示出包含谐波齿轮装置1的致动器100和机器人用关节装置130的概略结构的剖视图。
(3.1)谐波齿轮装置
如上所述，本实施方式的谐波齿轮装置1包括刚性内齿轮2、挠性外齿轮3和波发生器4。在本实施方式中，作为谐波齿轮装置1的结构要素的刚性内齿轮2、挠性外齿轮3和波发生器4的材质为不锈钢、铸铁、机械结构用碳素钢、铬钼钢、磷青铜或铝青铜等金属。此处所说的金属包含实施了渗氮处理等表面处理的金属。
另外，在本实施方式中，作为谐波齿轮装置1的一例，例示杯型的波动减速装置。也就是说，在本实施方式的谐波齿轮装置1中使用形成为杯状的挠性外齿轮3。波发生器4以被收容于杯状的挠性外齿轮3内的方式与挠性外齿轮3进行组合。
另外，作为本实施方式中的一例，谐波齿轮装置1在刚性内齿轮2固定于输入侧壳体111(参照图4)和输出侧壳体112(参照图4)等的状态下被使用。由此，伴随着刚性内齿轮2与挠性外齿轮3的相对旋转，挠性外齿轮3相对于固定构件(输入侧壳体111等)进行相对旋转。
进一步，在本实施方式中，在将谐波齿轮装置1用于致动器100的情况下，通过向波发生器4施加作为输入的旋转力，从而能够从挠性外齿轮3取出作为输出的旋转力。也就是说，谐波齿轮装置1将波发生器4的旋转作为输入旋转，并将挠性外齿轮3的旋转作为输出旋转而动作。由此，在谐波齿轮装置1中，能够得到相对于输入旋转以较高的减速比减速了的输出旋转。
进一步，在本实施方式的谐波齿轮装置1中，输入侧的旋转轴Ax1和输出侧的旋转轴Ax2在同一直线上。换言之，输入侧的旋转轴Ax1和输出侧的旋转轴Ax2为同轴。此处，输入侧的旋转轴Ax1是施加有输入旋转的 波发生器4的旋转中心，输出侧的旋转轴Ax1是产生输出旋转的挠性外齿轮3的旋转中心。也就是说，在谐波齿轮装置1中，在同轴上，能够得到相对于输入旋转以较高的减速比减速了的输出旋转。
刚性内齿轮2也称为刚轮(circular spline)，其为具有内齿21的环状的部件。在本实施方式中，刚性内齿轮2具有至少内周面在俯视时为正圆的圆环状。在圆环状的刚性内齿轮2的内周面，沿着刚性内齿轮2的圆周方向形成有内齿21。构成内齿21的多个齿为全部相同的形状，且以等间距设置在刚性内齿轮2的内周面的圆周方向的整个区域。也就是说，内齿21的节圆在俯视观察下为正圆。另外，刚性内齿轮2在旋转轴Ax1的方向上具有规定的厚度。内齿21均形成于刚性内齿轮2的厚度方向的整个长度上。内齿21的齿向都与旋转轴Ax1平行。
如上所述，刚性内齿轮2固定于输入侧壳体111(参照图4)和输出侧壳体112(参照图4)等。因此，在刚性内齿轮2形成有固定用的多个固定孔22(参照图3A和图3B)。
挠性外齿轮3也称为柔轮(flex spline)，其为具有外齿31的环状的部件。在本实施方式中，挠性外齿轮3是使用比较薄壁的金属弹性体(金属板)形成为杯状的部件。也就是说，挠性外齿轮3由于其厚度比较小(薄)而拥有挠性。挠性外齿轮3具有杯状的主体部32。主体部32具有躯体部321和底部322。在挠性外齿轮3未产生弹性变形的状态下，躯体部321的至少内周面301具有在俯视时为正圆的圆筒状。躯体部321的中心轴与旋转轴Ax1一致。底部322配置于躯体部321的一方的开口面，并具有在俯视时为正圆的圆盘状。底部322配置于躯体部321的一对开口面中的、靠旋转轴Ax1的输出侧的开口面。根据上述内容，主体部32通过躯体部321和底部322的整体实现在旋转轴Ax1的输入侧开放的、有底的圆筒状即杯状的形状。换言之，在挠性外齿轮3的旋转轴Ax1的方向上的与底部322相反一侧的端面形成有开口面35。也就是说，挠性外齿轮3是在齿向方向 D1的一侧(此处为旋转轴Ax1的输入侧)具有开口面35的筒状。在本实施方式中，躯体部321和底部322由一个金属构件一体形成，由此能够实现无缝的主体部32。
此处，以在躯体部321的内侧嵌入非圆形状(椭圆形状)的波发生器4的方式使波发生器4与挠性外齿轮3组合。由此，挠性外齿轮3从内侧朝向外侧地、从波发生器4受到径向方向(与旋转轴Ax1正交的方向)的外力，由此弹性变形为非圆形状。在本实施方式中，通过使波发生器4与挠性外齿轮3组合，挠性外齿轮3的躯体部321弹性变形为椭圆形状。也就是说，挠性外齿轮3未产生弹性变形的状态是指波发生器4未与挠性外齿轮3组合的状态。相反，挠性外齿轮3产生弹性变形的状态是指波发生器4与挠性外齿轮3组合好的状态。
更详细地说，波发生器4嵌入躯体部321的内周面301中的与底部322相反一侧(旋转轴Ax1的输入侧)的端部。换言之，波发生器4嵌入挠性外齿轮3的躯体部321中的、旋转轴Ax1的方向上的开口面35侧的端部。因此，在挠性外齿轮3产生弹性变形的状态下，挠性外齿轮3在旋转轴Ax1的方向上的开口面35侧的端部处变形得比底部322侧的端部大，成为更接近椭圆形状的形状。根据这样的在旋转轴Ax1的方向上的变形量的不同，在挠性外齿轮3产生弹性变形的状态下，挠性外齿轮3的躯体部321的内周面301包含相对于旋转轴Ax1倾斜的渐缩面302(参照图9)。
另外，在躯体部321的外周面中的至少与底部322相反的一侧(旋转轴Ax1的输入侧)的端部沿着躯体部321的圆周方向形成有外齿31。换言之，外齿31设于挠性外齿轮3的躯体部321中的、至少在旋转轴Ax1的方向上的开口面35侧的端部。构成外齿31的多个齿为全部相同的形状，且以等间距设置在挠性外齿轮3的外周面的圆周方向的整个区域。也就是说，外齿31的节圆在挠性外齿轮3未产生弹性变形的状态下，在俯视时为正圆。外齿31仅形成于从躯体部321的开口面35侧(旋转轴Ax1的输入侧)的 端缘起的一定宽度的范围内。具体而言，在躯体部321中的、在旋转轴Ax1的方向上至少供波发生器4嵌入的部分(开口面35侧的端部)且在外周面形成有外齿31。外齿31的齿向均与旋转轴Ax1平行。
总之，在本实施方式的谐波齿轮装置1中，刚性内齿轮2的内齿21和挠性外齿轮3的外齿31的任一齿向均与旋转轴Ax1平行。由此，在本实施方式中，“齿向方向D1”为与旋转轴Ax1平行的方向。并且，内齿21的齿向方向D1的尺寸是内齿21的齿宽，同样，外齿31的齿向方向D1的尺寸是外齿31的齿宽，因此齿向方向D1与齿宽方向同义。
如上所述，在本实施方式中，挠性外齿轮3的旋转作为输出旋转被取出。因此，在挠性外齿轮3安装有致动器100的输出部102(参照图4)。在挠性外齿轮3的底部322形成有用于安装作为输出部102的轴的多个安装孔33。进一步，在底部322的中央部形成有穿透孔34。底部322中的穿透孔34的周围比底部322的其他部位壁厚。
如此构成的挠性外齿轮3配置于刚性内齿轮2的内侧。此处，挠性外齿轮3以仅躯体部321的外周面中的与底部322相反的一侧(旋转轴Ax1的输入侧)的端部插入于刚性内齿轮2的内侧的方式与刚性内齿轮2进行组合。也就是说，挠性外齿轮3的躯体部321中的、在旋转轴Ax1的方向上供波发生器4嵌入的部分(开口面35侧的端部)插入于刚性内齿轮2的内侧。此处，在挠性外齿轮3的外周面形成有外齿31，并在刚性内齿轮2的内周面形成有内齿21。因此，在挠性外齿轮3配置于刚性内齿轮2的内侧的状态下，外齿31与内齿21彼此相对。
此处，刚性内齿轮2中的内齿21的齿数比挠性外齿轮3的外齿31的齿数多2N(N为正整数)。作为本实施方式的一例，N为“1”，挠性外齿轮3的(外齿31的)齿数比刚性内齿轮2的(内齿21的)齿数多“2”。这种挠性外齿轮3与刚性内齿轮2的齿数差规定了谐波齿轮装置1中的、输出旋转相对于输入旋转而言的减速比。
此处，在本实施方式中，作为一例，如图1A和图1B所示，以外齿31的齿向方向D1的中心与内齿21的齿向方向D1的中心相对的方式设定旋转轴Ax1的方向上的挠性外齿轮3与刚性内齿轮2的相对位置。也就是说，在挠性外齿轮3的外齿31与刚性内齿轮2的内齿21中，齿向方向D1的中心的位置对准旋转轴Ax1的方向的同一位置。另外，在本实施方式中，外齿31的齿向方向D1的尺寸(齿宽)比内齿21的齿向方向D1的尺寸(齿宽)大。因此，在与旋转轴Ax1平行的方向上，内齿21收敛于外齿31的齿向的范围内。换言之，外齿31相对于内齿21向齿向方向D1的至少一侧突出。在本实施方式中，外齿31相对于内齿21向齿向方向D1的两侧(旋转轴Ax1的输入侧和输出侧)突出。
此处，在挠性外齿轮3未产生弹性变形的状态(挠性外齿轮3未与波发生器4组合的状态)下，描绘正圆的外齿31的节圆设定为比同样描绘正圆的内齿21的节圆小一圈。也就是说，在挠性外齿轮3未产生弹性变形的状态下，外齿31与内齿21隔着间隙相对，彼此未啮合。
另一方面，在挠性外齿轮3产生弹性变形的状态(波发生器4与挠性外齿轮3组合好的状态)下，由于躯体部321挠曲为椭圆形状(非圆形状)，所以挠性外齿轮3的外齿31与刚性内齿轮2的内齿21局部地啮合。也就是说，如图2A所示，挠性外齿轮3的躯体部321(的至少开口面35侧的端部)弹性变形为椭圆形状，由此位于椭圆形状的长轴方向的两端的外齿31与内齿21啮合。换言之，椭圆形状的外齿31的节圆的长径与正圆形状的内齿21的节圆的直径一致，椭圆形状的外齿31的节圆的短径比正圆形状的内齿21的节圆的直径小。如此，当挠性外齿轮3产生弹性变形时，构成外齿31的多个齿中的一部分齿与构成内齿21的多个齿中的一部分齿啮合。从结果来看，在谐波齿轮装置1中，能够使外齿31的一部分与内齿21的一部分啮合。
波发生器4也称为波形发生器(wave generator)，其是使挠性外齿轮3 产生挠曲，从而使挠性外齿轮3的外齿31产生谐波运动的部件。在本实施方式中，波发生器4是俯视时外周形状为非圆形状、具体而言为椭圆形状的部件。
波发生器4具有非圆形状(此处为椭圆形状)的凸轮41和装配于凸轮41的外周的轴承42。也就是说，凸轮41与轴承42组合成在轴承42的内圈422的内侧嵌入有非圆形状(椭圆形状)的凸轮41。由此，轴承42从内圈422的内侧朝向外侧受到来自凸轮41的径向方向(与旋转轴Ax1正交的方向)的外力，从而弹性变形为非圆形状。也就是说，轴承42未产生弹性变形的状态是指凸轮41未与轴承42组合的状态。相反，轴承42产生弹性变形的状态是指凸轮41与轴承42组合好的状态。
凸轮41是以输入侧的旋转轴Ax1为中心被旋转驱动的非圆形状(此处为椭圆形状)的部件。凸轮41具有外周面411(参照图1B)，至少外周面411由在俯视时为椭圆形状的金属板构成。凸轮41在旋转轴Ax1的方向(也就是说齿向方向D1)上拥有规定的厚度。由此，凸轮41具有与刚性内齿轮2同等程度的刚性。但是，凸轮41的厚度与刚性内齿轮2的厚度相比小(薄)。如上所述，在本实施方式中，将波发生器4的旋转作为输入旋转。因此，在波发生器4安装有致动器100的输入部103(参照图4)。在波发生器4的凸轮41的中央部形成有用于安装作为输入部103的轴的凸轮孔43。
轴承42具有外圈421、内圈422和多个滚动体423。在本实施方式中，作为一例，轴承42由使用球体状的滚珠作为滚动体423的深沟球轴承构成。
外圈421和内圈422均为环状的部件。外圈421和内圈422均是使用壁较薄的金属弹性体(金属板)形成为环状的部件。也就是说，外圈421和内圈422由于其厚度比较小(薄)而均拥有挠性。在本实施方式中，外圈421和内圈422在轴承42未产生弹性变形的状态(凸轮41未与轴承42组合的状态)下，均具有俯视时为正圆的、圆环状。内圈422比外圈421小一圈并配置于外圈421的内侧。此处，外圈421的内径比内圈422的外 径大，因此在外圈421的内周面425与内圈422的外周面之间产生间隙。
多个滚动体423配置于外圈421与内圈422之间的间隙。多个滚动体423沿外圈421的圆周方向排列配置。多个滚动体423为全部相同的形状的金属球(滚珠)，且以等间距设置在外圈421的圆周方向的整个区域。此处虽然未特别图示，但是轴承42还具有保持器，多个滚动体423通过保持器被保持于外圈421与内圈422之间。
另外，在本实施方式中，作为一例，外圈421和内圈422的宽度方向(与旋转轴Ax1平行的方向)的尺寸与凸轮41的厚度相同。也就是说，外圈421和内圈422的宽度方向的尺寸比刚性内齿轮2的厚度小。
通过这种轴承42的结构，凸轮41与轴承42组合，由此轴承42的内圈422固定于凸轮41，内圈422弹性变形为与凸轮41的外周形状相似的椭圆形状。此时，轴承42的外圈421经由多个滚动体423被内圈422按压而弹性变形为椭圆形状。由此，轴承42的外圈421和内圈422均弹性变形为椭圆形状。如此，在轴承42产生弹性变形的状态(凸轮41与轴承42组合好的状态)下，外圈421和内圈422成为彼此相似的椭圆形状。
即使是在轴承42产生弹性变形的状态下，由于多个滚动体423介于外圈421与内圈422之间，所以外圈421与内圈422之间的间隙在外圈421的整周被维持为大致恒定。并且，在该状态下，通过外圈421与内圈422之间的多个滚动体423滚动，从而外圈421能够相对于内圈422进行相对旋转。由此，在轴承42产生弹性变形的状态下，当凸轮41以旋转轴Ax1为中心旋转时，凸轮41的旋转不传动至外圈421，而内圈422的弹性变形经由多个滚动体423传动至外圈421。也就是说，在波发生器4中，当凸轮41以旋转轴Ax1为中心旋转时，外圈421以由外圈421仿效的椭圆形状的长轴以旋转轴Ax1为中心进行旋转的方式弹性变形。因此，作为波发生器4整体而言，从旋转轴Ax1的输入侧观察到的、成为椭圆形状的波发生器4的外周形状以其长轴以旋转轴Ax1为中心进行旋转的方式伴随着凸轮41的 旋转而变化。
如此构成的波发生器4配置于挠性外齿轮3的内侧。此处，挠性外齿轮3以仅躯体部321的内周面301中的与底部322相反一侧(开口面35侧)的端部与波发生器4嵌合的方式与波发生器4组合。此时，波发生器4的轴承42配置于凸轮41的外周面411与挠性外齿轮3的内周面301之间。此处，在轴承42未产生弹性变形的状态(凸轮41未与轴承42组合的状态)下的外圈421的外径与同样未产生弹性变形状态下的挠性外齿轮3(躯体部321)的内径相同。因此，波发生器4中的外圈421的外周面424(参照图5)遍及轴承42的圆周方向的整周而与挠性外齿轮3的内周面301相接。由此，在挠性外齿轮3产生了弹性变形的状态(波发生器4与挠性外齿轮3组合的状态)下，躯体部321挠曲为椭圆形状(非圆形状)。在该状态下，挠性外齿轮3相对于轴承42的外圈421被固定。
但是，由于只是挠性外齿轮3与波发生器4嵌合，因此挠性外齿轮3与轴承42的外圈421并不是完全固定。因此，如上所述，在挠性外齿轮3与嵌入挠性外齿轮3的内侧的外圈421之间，虽说微小但还是会产生间隙X1(参照图1B)。严格来说，外圈421的外周面424的直径比挠性外齿轮3的内周面301的直径稍小，因此外圈421与挠性外齿轮3之间的间隙X1不会被完全填埋，至少局部地产生间隙X1。并且，也存在这样的间隙X1的影响，伴随着波发生器4的凸轮41旋转而外圈421和挠性外齿轮3产生弹性变形，在外圈421与挠性外齿轮3之间可能产生相对旋转。该相对旋转例如是凸轮41的转速的几千分之一或者几百分之一左右的旋转，但是由于这样的相对旋转而使外圈421与挠性外齿轮3产生相对相互摩擦是微动磨损的一个原因。
本公开所说的“间隙”是指在2个物体的相对面之间可能产生的空间，即使这2个物体不分离也可能在两者之间产生间隙。也就是说，即使2个物体接触，在这2个物体之间虽说微小但还是有可能产生间隙。在挠性外 齿轮3与嵌入挠性外齿轮3的内侧的外圈421之间，在相互相对的外圈421的外周面424与挠性外齿轮3的内周面301之间产生间隙X1。但是，由于基本上外圈421的外周面424与挠性外齿轮3的内周面301接触，因此两者间不会产生大的间隙X1。因此，外圈421与挠性外齿轮3之间的间隙X1是在外圈421的外周面424与挠性外齿轮3的内周面301之间可局部产生的微小的间隙。作为一例，在外圈421的外周面424与挠性外齿轮3的内周面301产生能够供润滑剂Lb1浸透的程度的微观的间隙X1。
如图2A所示，在上述构成的谐波齿轮装置1中，通过挠性外齿轮3的躯体部321挠曲为椭圆形状(非圆形状)，从而挠性外齿轮3的外齿31与刚性内齿轮2的内齿21局部性地啮合。也就是说，通过挠性外齿轮3(的躯体部321)弹性变形为椭圆形状，从而与该椭圆形状的长轴方向的两端相当的两部位的外齿31啮合于内齿21。并且，当凸轮41以旋转轴Ax1为中心旋转时，凸轮41的旋转不传动至外圈421和挠性外齿轮3，而内圈422的弹性变形经由多个滚动体423传动至外圈421和挠性外齿轮3。因此，从旋转轴Ax1的输入侧观察到的、成为椭圆形的挠性外齿轮3的外周形状以其长轴以旋转轴Ax1为中心进行旋转的方式伴随着凸轮41的旋转而变化。
其结果，在形成于挠性外齿轮3的外周面的外齿31发生谐波运动。由于发生外齿31的谐波运动，所以内齿21与外齿31的啮合位置沿刚性内齿轮2的圆周方向移动，从而在挠性外齿轮3与刚性内齿轮2之间产生相对旋转。也就是说，外齿31由于在挠性外齿轮3(的躯体部321)所形成的椭圆形状的长轴方向的两端处与内齿21啮合，所以通过该椭圆形状的长轴以旋转轴Ax1为中心进行旋转，从而使内齿21与外齿31的啮合位置移动。如此，对于本实施方式所涉及的谐波齿轮装置1而言，伴随着以旋转轴Ax1为中心的波发生器4的旋转而使挠性外齿轮3变形，使外齿31的一部分与内齿21的一部分啮合，从而使挠性外齿轮3按照与刚性内齿轮2的齿数差而进行旋转。
另外，如上所述，在谐波齿轮装置1中，挠性外齿轮3与刚性内齿轮2的齿数差规定了在谐波齿轮装置1中的、输出旋转相对于输入旋转而言的减速比。也就是说，在将刚性内齿轮2的齿数设为“V1”、将挠性外齿轮3的齿数设为“V2”的情况下，减速比R1以下述式1表示。
R1＝V2/(V1-V2)……(式1)
总而言之，刚性内齿轮2与挠性外齿轮3的齿数差(V1-V2)越小则减速比R1越大。作为一例，若刚性内齿轮2的齿数V1为“72”且挠性外齿轮3的齿数V2为“70”，其齿数差(V1-V2)为“2”，则根据上述式1，减速比R1为“35”。在这样的情况下，从旋转轴Ax1的输入侧观察时，当凸轮41以旋转轴Ax1为中心顺时针旋转一周(360度)时，挠性外齿轮3以旋转轴Ax1为中心逆时针仅旋转齿数差“2”的量(即、10.3度)。
根据本实施方式所涉及的谐波齿轮装置1，如此高的减速比R1能够由一级的齿轮(刚性内齿轮2与挠性外齿轮3)的组合来实现。
另外，波齿轮装置1只要至少包括刚性内齿轮2、挠性外齿轮3和波发生器4即可，还可以包括例如“(3.2)致动器”一栏中说明的花键衬套113等作为构成要素。
(3.2)致动器
接下来，对于本实施方式所涉及的致动器100的结构进行更详细的说明。
如图4所示，本实施方式所涉及的致动器100包括本实施方式的谐波齿轮装置1、驱动源101和输出部102。也就是说，致动器100除了构成谐波齿轮装置1的刚性内齿轮2、挠性外齿轮3和波发生器4，还包括驱动源101和输出部102。另外，致动器100除了谐波齿轮装置1、驱动源101和输出部102之外，还包括输入部103、输入侧壳体111、输出侧壳体112、花键衬套113、间隔件114、第一止挡件115、第二止挡件116和安装板117。另外，在本实施方式中，致动器100还包括输入侧轴承118、119，输入侧 油封120，输出侧轴承121、122和输出侧油封123。
在本实施方式中，致动器100中的、除驱动源101、输入侧油封120和输出侧油封123以外的部件的材质为不锈钢、铸铁、机械结构用碳素钢、铬钼钢、磷青铜或铝青铜等金属。
驱动源101是电动机(电动机)等动力的产生源。驱动源101所产生的动力传递至谐波齿轮装置1中的波发生器4的凸轮41。具体而言，驱动源101与作为输入部103的轴连接，驱动源101所产生的动力经由输入部103传递至凸轮41。由此，驱动源101能够使凸轮41旋转。
输出部102是沿着输出侧的旋转轴Ax2配置的圆柱状的轴。作为输出部102的轴的中心轴与旋转轴Ax2一致。输出部102通过输出侧壳体112保持为能够以旋转轴Ax2为中心旋转。输出部102固定于挠性外齿轮3中的主体部32的底部322，并以旋转轴Ax2为中心与挠性外齿轮3一起旋转。也就是说，输出部102将挠性外齿轮3的旋转力作为输出而取出。
输入部103是沿着输入侧的旋转轴Ax1配置的圆柱状的轴。作为输入部103的轴的中心轴与旋转轴Ax1一致。输入部103通过输入侧壳体111保持为能够以旋转轴Ax1为中心旋转。输入部103安装于波发生器4的凸轮41，并以旋转轴Ax1为中心与凸轮41一起旋转。也就是说，输入部103将驱动源101所产生的动力(旋转力)作为输入传递至凸轮41。如上所述，在本实施方式中，输入侧的旋转轴Ax1与输出侧的旋转轴Ax2位于同一直线上，因此输入部103与输出部102位于同轴上。
输入侧壳体111经由输入侧轴承118、119将输入部103保持为输入部103能够旋转。一对输入侧轴承118、119沿着旋转轴Ax1空出间隔而排列配置。在本实施方式中，作为输入部103的轴贯通输入侧壳体111，且输入部103的前端部从输入侧壳体111中的旋转轴Ax1的输入侧的端面(图4的右端面)突出。输入侧壳体111的旋转轴Ax1的输入侧的端面中的与输入部103之间的间隙由输入侧油封120堵塞。
输出侧壳体112经由输出侧轴承121、122将输出部102保持为输出部102能够旋转。一对输出侧轴承121、122沿着旋转轴Ax2空出间距而排列配置。在本实施方式中，作为输出部102的轴贯通输出侧壳体112，且输出部102的前端部从输出侧壳体112中的旋转轴Ax1的输出侧的端面(图4的左端面)突出。输出侧壳体112的旋转轴Ax1的输出侧的端面中的与输出部102之间的间隙由输出侧油封123堵塞。
此处，如图4所示，输入侧壳体111和输出侧壳体112在从与旋转轴Ax1平行的方向、即齿向方向D1的两侧夹着谐波齿轮装置1的刚性内齿轮2的状态下相互结合。具体而言，输入侧壳体111从旋转轴Ax1的输入侧与刚性内齿轮2接触，输出侧壳体112从旋转轴Ax1的输出侧与刚性内齿轮2接触。如此，在将刚性内齿轮2夹持于输入侧壳体111与输出侧壳体112之间的状态下，穿过多个固定孔22利用螺钉(螺栓)使输入侧壳体111与输出侧壳体112紧固固定。由此，输入侧壳体111、输出侧壳体112和刚性内齿轮2彼此结合而成为一体。换言之，刚性内齿轮2与输入侧壳体111和输出侧壳体112一起构成致动器100的外轮廓。
花键衬套113是用于将作为输入部103的轴连接于凸轮41的筒状部件。花键衬套113插入于形成在凸轮41的凸轮孔43，作为输入部103的轴以贯通花键衬套113的方式插入于花键衬套113。此处，在以旋转轴Ax1为中心的旋转方向上，花键衬套113相对于凸轮41和输入部103这两者的移动被限制，在与旋转轴Ax1平行的方向上，花键衬套113至少能够相对于输入部103移动。由此，作为输入部103与凸轮41的连结结构，能够实现花键连结结构。由此，凸轮41能够相对于输入部103沿着旋转轴Ax1移动，并以旋转轴Ax1为中心与输入部103一起旋转。
间隔件114是填补花键衬套113与凸轮41之间的间隙的部件。第一止挡件115是防止花键衬套113从凸轮41脱落的部件。第一止挡件115例如由E型圈构成，安装于花键衬套113中的从凸轮41观察时旋转轴Ax1的输 入侧的位置。第二止挡件116是防止输入部103从花键衬套113脱落的部件。第二止挡件116例如由E型圈构成，以从旋转轴Ax1的输出侧与花键衬套113接触的方式安装于输入部103。
安装板117是用于将作为输出部102的轴安装于挠性外齿轮3的底部322的部件。具体而言，在将底部322中的穿透孔34的周围的部分夹持于安装板117与输出部102的凸缘部之间的状态下，穿过多个安装孔33利用螺钉(螺栓)使安装板117与凸缘部紧固固定。由此，在挠性外齿轮3的底部322固定有作为输出部102的轴。
但是，在本实施方式中，在由输入侧壳体111、输出侧壳体112和刚性内齿轮2构成的致动器100的外轮廓的内侧封入有润滑剂Lb1。也就是说，在被输入侧壳体111、输出侧壳体112和刚性内齿轮2包围的空间内存在能够贮存液态或凝胶态的润滑剂Lb1的“润滑剂储存处”。
即，在本实施方式的谐波齿轮装置1中，例如在内齿21与外齿31的啮合部分和轴承42的外圈421与内圈422之间等注入有液态或凝胶态的润滑剂Lb1。作为一例，润滑剂Lb1是液态的润滑油(油液)。并且，在谐波齿轮装置1使用时，润滑剂Lb1也进入轴承42的外圈421(外周面424)与挠性外齿轮3之间的间隙X1。
如图4所示，在本实施方式中，作为一例，以润滑剂Lb1的液面位于比输出侧轴承121、122的下端更靠下方的方式仅在致动器100的外轮廓的下部(铅垂方向的下部)贮存润滑剂Lb1。因此，关于外齿31和轴承42的外圈421等，在图4的状态下，仅旋转方向上的一部分浸于润滑剂Lb1。当输出部102从该状态伴随着输入部103的旋转而旋转时，外圈421和挠性外齿轮3也围绕旋转轴Ax1旋转，因此结果是外齿31和轴承42的外圈421等在整个旋转方向上浸于润滑剂Lb1。
(3.3)机器人用关节装置
接下来，对本实施方式的机器人用关节装置130的结构进行更详细的 说明。
如图4所示，本实施方式的机器人用关节装置130包括本实施方式的谐波齿轮装置1、第一构件131和第二构件132。也就是说，机器人用关节装置130除了构成谐波齿轮装置1的刚性内齿轮2、挠性外齿轮3和波发生器4，还包括第一构件131和第二构件132。
第一构件131是固定于刚性内齿轮2的构件，第二构件132是固定于挠性外齿轮3的构件。因此，在谐波齿轮装置1中，在挠性外齿轮3与刚性内齿轮2之间产生相对旋转，由此在第一构件131与第二构件132之间也产生相对旋转。如此，机器人用关节装置130构成经由谐波齿轮装置1将2个以上的构件(第一构件131和第二构件132)以相互可动的状态连结(可动连结)时的结合部位。
此处，第一构件131和第二构件132只要分别直接或间接地固定于刚性内齿轮2和挠性外齿轮3即可。在图4的例子中，第一构件131通过与输出侧壳体112结合，从而间接地与刚性内齿轮2结合(固定)。同样，第二构件132通过与输出部102结合，从而间接地与挠性外齿轮3结合(固定)。
在这样构成的机器人用关节装置130中，例如，当在由驱动源101产生的动力的作用下波发生器4的凸轮41旋转时，在挠性外齿轮3与刚性内齿轮2之间产生相对旋转。并且，伴随着挠性外齿轮3与刚性内齿轮2的相对旋转，在第一构件131与第二构件132之间，以输出侧的旋转轴Ax2(与输入侧的旋转轴Ax1同轴)为中心产生相对旋转。结果是，根据机器人用关节装置130，能够将经由谐波齿轮装置1连结的第一构件131和第二构件132驱动成以旋转轴Ax1为中心相对地旋转。由此，机器人用关节装置130能够实现各种各样的机器人的关节机构。
(4)各部的详细的结构
接下来，参照图1A～图2B、图5～图8B对本实施方式的谐波齿轮装置 1的各部的更详细的结构进行更详细的说明。
图5对相当于图1B的范围放大主要部分而得的概略剖视图。图6A是表示图5的区域Z1中的挠性外齿轮3的内周面301的表面状态的概略图，图6B是表示图5的区域Z2中的挠性外齿轮3的内周面301的表面状态的概略图。图7是图2B的区域Z1放大概略图。图8A是表示图7的区域Z1中的外齿31的表面状态的概略图，图8B是表示图7的区域Z2中的外齿31的表面状态的概略图。
(4.1)贯通孔
如图1A和图1B所示，在本实施方式中，在轴承42的外圈421与挠性外齿轮3中的外齿31的至少一者设有贯通孔H1，该贯通孔H1沿着径向方向贯通且与外圈421和挠性外齿轮3之间的间隙X1相连。也就是说，轴承42的外圈421中的成为多个滚动体423的滚动面的内周面425(参照图5)、以及、挠性外齿轮3的外齿31中的成为与内齿21的啮合面的外周面这两者中的至少一者通过贯通孔H1而与间隙X1相通。因此，能够通过贯通孔H1将润滑剂Lb1供给至外圈421与挠性外齿轮3之间的间隙X1。
也就是说，本实施方式的谐波齿轮装置1通过设置贯通孔H1，能够经由贯通孔H1将润滑剂Lb1供给至挠性外齿轮3与波发生器4接触部位，由此在接触部位维持充分的润滑剂Lb1。其结果，防止“润滑剂耗尽”，外圈421与挠性外齿轮3的接触部位的表面成为被润滑剂Lb1覆盖的状态，抑制微动磨损的发生。由此，在本实施方式的谐波齿轮装置1中，难以产生因外圈421与挠性外齿轮3之间的微动磨损而引起的不良情况，能够提供难以产生可靠性的下降的谐波齿轮装置1。
但是，贯通孔H1只要设于外圈421与挠性外齿轮3中的外齿31的至少一者即可。在本公开中，在对分别设于外圈421与挠性外齿轮3中的外齿31的贯通孔H1进行区分的情况下，将设于外圈421的贯通孔H1称为“第一贯通孔”，将设于挠性外齿轮3的外齿31的贯通孔H2(参照图17B) 称为“第二贯通孔”。在本实施方式中，作为一例，贯通孔H1仅设于外圈421与挠性外齿轮3中的外齿31之中的外圈421。换言之，在本实施方式中，贯通孔H1包含设于外圈421“第一贯通孔”。另一方面，关于挠性外齿轮3的外齿31侧的贯通孔H2(第二贯通孔)在“(8)变形例”中进行说明。
另外，本公开所说的“沿着径向方向贯通”是指沿着径向方向、也就是与旋转轴Ax1正交的方向即径向贯通。即，只要是如本实施方式那样设于外圈421的贯通孔H1，则贯通孔H1只要在外圈421的径向方向的两面即内周面425和外周面424之间贯通即可，例如，也可以相对于径向方向倾斜。
此处，首先参照图5对本实施方式中的贯通孔H1的形状和尺寸进行说明。
设于外圈421的贯通孔H1(第一贯通孔)沿着径向方向贯通外圈421。由此，贯通孔H1的一侧的开口面面向外圈421与挠性外齿轮3之间的间隙X1，贯通孔H1的另一侧的开口面在外圈421的内周面425开口。因此，贯通孔H1的一端与外圈421和挠性外齿轮3之间的间隙X1相连，另一端与外圈421的内周面425和内圈422的外周面之间的空间相连。因此，配置有多个滚动体423的外圈421的内周面425与内圈422的外周面之间的空间隔着贯通孔H1而与外圈421和挠性外齿轮3之间的间隙X1连通。
另外，贯通孔H1是与径向方向正交的剖面形状为圆形(正圆)状的圆孔。在本实施方式中，作为一例，贯通孔H1的中心线与径向方向平行。也就是说，贯通孔H1是从外圈421的内周面425到外周面424沿着径向方向笔直延伸的孔。进一步，贯通孔H1的与径向方向正交的剖面形状在径向方向上的贯通孔H1的全长范围内为相同形状。也就是说，在贯通孔H1的内部形成有圆柱状的空间。
此处，贯通孔H1的径φ1(参照图5)是多个滚动体423各自的径φ2 (参照图5)的0.1倍以下和1.0mm以下这两者中较小的一方。此处所说的贯通孔H1的径φ1在贯通孔H1的剖面形状为正圆的情况下是指贯通孔H1的直径，在贯通孔H1的剖面形状为非圆形状(例如椭圆形状)的情况下是指贯通孔H1的短轴方向的尺寸。在本实施方式中，作为一例，贯通孔H1的径φ1为滚动体423的径φ2的0.1倍以下且1.0mm以下。根据这样的贯通孔H1的径φ1，通过贯通孔H1能够将润滑剂Lb1高效地供给至外圈421与挠性外齿轮3之间的间隙X1。
根据以上说明的结构，外圈421与内圈422之间的空间隔着贯通孔H1与外圈421和挠性外齿轮3之间的间隙X1相连，因此外圈421与内圈422之间的润滑剂Lb1通过贯通孔H1供给至间隙X1。在图5中，用虚线箭头示意性地表示贯通孔H1内的润滑剂Lb1的流动。特别是当轴承42动作而多个滚动体423旋转时，滚动体423作为泵发挥功能，能够将外圈421与内圈422之间的润滑剂Lb1经由贯通孔H1送入间隙X1。其结果，防止在外圈421与挠性外齿轮3的接触部位处润滑剂Lb1不足或枯竭的“润滑剂耗尽”，容易抑制微动磨损的发生。
总之，本实施方式的谐波齿轮装置1包括泵结构，该泵结构在挠性外齿轮3相对于刚性内齿轮2相对旋转时，通过贯通孔H1将润滑剂Lb1供给至间隙X1。在挠性外齿轮3相对于刚性内齿轮2相对旋转时，轴承42的多个滚动体423沿外圈421的周向滚动，因此如上所示，多个滚动体423作为泵发挥功能。也就是说，多个滚动体423构成泵结构。特别是，在本实施方式中，滚动体423在外圈421与内圈422之间的空间内滚动，由此外圈421与内圈422之间的空间内的压力升高，因此处于外圈421与内圈422之间的润滑剂Lb1通过贯通孔H1被挤出至间隙X1侧。如此，滚动体423构成叶片泵那样的容积型的泵，以充分的压力将润滑剂Lb1挤出至间隙X1侧，因此容易将充分的润滑剂Lb1供给至间隙X1内。
另外，贯通孔H1中的、外圈421的内周面425侧的开口面在形成于外 圈421的内周面425的滚动槽426的底面开口。也就是说，在外圈421的内周面425的宽度方向(齿向方向D1)的中央部形成有遍及外圈421的整周且沿周向延伸的滚动槽426，多个滚动体423沿着滚动槽426滚动。在内圈422的外周面也形成有同样的滚动槽427，多个滚动体423以被夹入的方式保持于这些相互相对的滚动槽426、427间。并且，贯通孔H1以在外圈421的滚动槽426的底面开口的方式配置于外圈421的宽度方向(齿向方向D1)上的形成有滚动槽426的范围内。
进一步，在本实施方式中，贯通孔H1在与旋转轴Ax1平行的方向(齿向方向D1)上配置于与多个滚动体423的中心相同的位置。换言之，贯通孔H1配置于外圈421的宽度方向(齿向方向D1)上的滚动槽426的中心。根据该结构，多个滚动体423的中心在贯通孔H1的开口面通过，在滚动体423旋转时，滚动体423作为泵高效地发挥作用，从而容易将润滑剂Lb1经由贯通孔H1送入间隙X1。进一步，可知外圈421与挠性外齿轮3主要在外圈421的宽度方向(齿向方向D1)的两端部接触。因此，贯通孔H1形成于外圈421的宽度方向(齿向方向D1)上的中心，由此在外圈421与挠性外齿轮3接触之际，难以产生因贯通孔H1而引起的外圈421的强度的下降。
此处，如图5所示，滚动槽426、427形成为与外圈421的周向正交的剖面形状为圆弧状。并且，滚动槽426、427的剖面形状的圆弧的曲率比多个滚动体423各自的曲率大。换言之，滚动槽426、427的剖面形状的圆弧的曲率半径比滚动体423的曲率半径小。因此，在多个滚动体423以被夹入的方式保持于滚动槽426、427之间的状态下，在滚动槽426、427的底面与各滚动体423的表面之间确保有一定程度的间隙。也就是说，如图5所示，各滚动体423在外圈421中的滚动槽426的宽度方向(齿向方向D1)的两端缘和内圈422中的滚动槽427的宽度方向(齿向方向D1)的两端缘总计四处被4点支承。但是，由于实际中在外圈421与内圈422之间相对 地施加推力方向(与旋转轴Ax1平行的方向)的负载，因此滚动体423由成为相互斜向相对的关系的一对端缘支承。
因此，在滚动槽426的底面形成的贯通孔H1的开口面隔着上述间隙而与滚动体423的表面相对。总之，在本实施方式中，在径向方向上，在多个滚动体423的轨道与设于外圈421的(第一)贯通孔H1的外圈421的内周面425侧的开口面之间确保有规定值以上的距离。也就是说，即使在滚动体423存在于与贯通孔H1对应的位置的状态下，在贯通孔H1的开口面与滚动体423之间也确保有规定值以上的距离(间隙)，贯通孔H1不会被滚动体423封闭。由此，在多个滚动体423滚动之际，即使滚动体423在贯通孔H1上通过，也不与贯通孔H1的开口缘碰撞。其结果，在滚动体423在贯通孔H1上通过之际，能够避免因滚动体423与贯通孔H1的开口缘碰撞而产生冲击，容易保护外圈421和滚动体423等免受冲击。
(4.2)贯通孔的数量和配置
接下来，参照图2A和图2B对本实施方式的贯通孔H1的数量和配置进行说明。
如图2A所示，贯通孔H1包含以沿外圈421的周向排列的方式设于外圈421的多个第一贯通孔。在本实施方式中，贯通孔H1仅由设于外圈421的第一贯通孔构成，因此多个贯通孔H1全部沿外圈421的周向排列配置。在本实施方式中，作为一例，在外圈421设有3个贯通孔H1。因此，能够在外圈421的周向的多个部位(在本实施方式中为3处)通过贯通孔H1将润滑剂Lb1供给至外圈421与挠性外齿轮3之间的间隙X1。其结果，与贯通孔H1在外圈421的周向上仅设于1处的情况相比，变得容易遍及间隙X1处的外圈421的周向的整个区域地供给润滑剂Lb1。
此处，如图2A所示，多个贯通孔H1(第一贯通孔)的间隔P1是多个滚动体423的间隔P2的倍数以外的值。在本实施方式中，作为一例，轴承42具有26个滚动体423，并在外圈421具有3个贯通孔H1。并且，26个 滚动体423和3个贯通孔H1分别在外圈421的周向上等间距(等间隔)地设置。因此，外圈421的周向上的3个贯通孔H1的间隔P1为120度(＝360度÷3)，外圈421的周向上的26个滚动体423的间隔P2为13.85度(＝360度÷26)。此处，间隔P1是以围绕旋转轴Ax1的角度来表示沿外圈421的周向相邻的2个贯通孔H1的中心间距离的值，同样，间隔P2是以围绕旋转轴Ax1的角度表示沿外圈421的周向相邻的2个滚动体423的中心间距离的值。在本实施方式中，为了这样即使对多个滚动体423的间隔P2(13.85度)乘以任何整数也与多个贯通孔H1的间隔P1(120度)不一致，将间隔P1设为不能被间隔P2整除那样的值。
由此，滚动体423不同时存在于与所有的贯通孔H1对应的位置。也就是说，在1个滚动体423位于与1个贯通孔H1对应的位置的状态下，滚动体423不位于与另外2个贯通孔H1对应的位置。因此，在本实施方式的谐波齿轮装置1中，能够避免多个滚动体423同时嵌进(或拔出)多个贯通孔H1时可能产生的比较大的冲击的发生，容易保护外圈421和滚动体423等免受冲击。另外，与滚动体423位于所有的贯通孔H1上的情况相比，基于滚动体423的滚动的泵作用也高效。
(4.3)挠性外齿轮的内周面的表面状态
接下来，参照图5、图6A和图6B对本实施方式的挠性外齿轮3的内周面301的表面状态进行说明。
如上所述，在本实施方式中，位于挠性外齿轮3的内周面301中的外齿31的背侧的第一区域R1形成为表面粗糙度比除第一区域R1以外的第二区域R2小。也就是说，挠性外齿轮3的内周面301包含表面粗糙度相互不同的第一区域R1与第二区域R2。并且，如图5所示，第一区域R1设于内周面301中的至少外齿31的背侧部位。第一区域R1与第二区域R2相比表面粗糙度小，也就是说第一区域R1具有更平滑的表面状态。波发生器4的轴承42与这样设于外齿31的背侧部位的第一区域R1接触。
总之，在挠性外齿轮3的内周面301中的第一区域R1与嵌入挠性外齿轮3的内侧的轴承42的外圈421之间虽说微小但还是会产生间隙X1。通过使润滑剂Lb1浸透到该间隙X1，抑制挠性外齿轮3与外圈421的接触部位处的微动磨损的发生。即，在本实施方式中，在第一区域R1与波发生器4的(轴承42的)外周面424之间保持有润滑剂Lb1。并且，如第一区域R1那样，通过使挠性外齿轮3的内周面301成为局部平滑的表面状态，从而润滑剂Lb1容易停留于挠性外齿轮3中的与波发生器4的接触部位，在接触部位能够维持充分的润滑剂Lb1。
另外，在本实施方式中，第一区域R1至少在与旋转轴Ax1平行的方向(齿向方向D1)上设于与波发生器4的(轴承42的)外周面424相对的面的整个区域。也就是说，如图5所示，挠性外齿轮3的内周面301中的与轴承42的外周面424相对的面的整个区域作为第一区域R1具有平滑的表面状态。其结果，挠性外齿轮3的内周面301中的与波发生器4的接触部位成为被润滑剂Lb1覆盖的状态，抑制微动磨损的发生。
此处，第一区域R1例如不是通过切削加工那样剪切金属的晶粒的加工而是通过不剪切金属的晶粒的加工(滚压加工)而形成的。因此，设于内周面301中的至少外齿31的背侧部位的第一区域R1成为金属的晶粒没有被剪切的、平滑的表面状态。另一方面，表面粗糙度相对大的第二区域R2例如通过切削加工、磨削加工或珩磨加工那样剪切金属的晶粒而形成。因此，内周面301中的第二区域R2成为金属的晶粒被剪切的表面状态。即，在本实施方式中，第一区域R1为滚压面，第二区域R2为切削面。这样，通过在第一区域R1和第二区域R2采用不同的加工，能够容易地调节第一区域R1与第二区域R2的表面粗糙度。
另外，第一区域R1设于挠性外齿轮3的内周面301中的、旋转轴Ax1的方向上的开口面35侧的端缘。也就是说，在本实施方式中，挠性外齿轮3是在外齿31的齿向方向D1的一侧(此处为旋转轴Ax1的输入侧)具有 开口面35的筒状。第一区域R1与开口面35连接。这样，通过在开口面35侧的端缘设置第一区域R1，在波发生器4从开口面35侧嵌入挠性外齿轮3之际，难以产生波发生器4卡挂于挠性外齿轮3的内周面301的情况。
如将挠性外齿轮3的内周面301的一部分(图5的区域Z1)放大的图6A所示，第一区域R1主要成为晶粒没有被剪切的平滑的表面状态。对此，如将挠性外齿轮3的内周面301的一部分(图5的区域Z2)放大的图6B所示，第二区域R2主要成为晶粒被剪切的表面状态。在本实施方式中，作为一例，“表面粗糙度”是由与旋转轴Ax1平行的方向(齿向方向D1)上的算数平均粗糙度(Ra)求出的值。如图6A和图6B所示表明，在规定了齿向方向D1的单位长度W1(作为一例0.25mm)和纵向倍率的方向的单位长度Y1(作为一例1μm)的情况下，第一区域R1的表面粗糙度比第二区域R2的表面粗糙度小。
此处，第一区域R1的表面粗糙度优选为第二区域R2的表面粗糙度的1/40倍以上且1/10倍以下。第一区域R1的表面粗糙度不限于第二区域R2的表面粗糙度的1/40倍以上，例如也可以1/80倍以上、1/50倍以上、1/30倍以上或1/20倍以上等。同样，第一区域R1的表面粗糙度不限于第二区域R2的表面粗糙度的1/10倍以下，例如也可以为1/2倍以下、1/5倍以下、1/16倍以下或1/20倍以下等。这样，第一区域R1的表面粗糙度为比第二区域R2的表面粗糙度足够小的值，因此润滑剂Lb1容易停留在第一区域R1处。作为一例，第一区域R1的表面粗糙度优选为Ra0.01以上且Ra0.1以下，在该情况下优选为第二区域R2的表面粗糙度(Ra)的1/10倍以下。
即，在通过对挠性外齿轮3的内周面301例如实施如切削加工、磨削加工或珩磨加工那样剪切金属组织的晶粒的加工而形成的第二区域R2中，在晶界产生鳞状的“毛刺”(凸部)。另一方面，在通过对挠性外齿轮3的内周面301例如实施如滚压加工那样不剪切金属组织的晶粒的加工而形成的第一区域R1中，不产生这样的鳞状的“毛刺”，而实现平滑的表面状 态。但是，“表面粗糙度”不限于与旋转轴Ax1平行的方向(齿向方向D1)上的算数平均粗糙度(Ra)。“表面粗糙度”可以是例如挠性外齿轮3的周向上的算数平均粗糙度(Ra)或者最大高度(Ry)、十点平均粗糙度(Rz)、凹凸的平均间隔(Sm)、局部山顶的平均间隔(S)又或是负载长度率(tp)等。
另外，为了使润滑剂Lb1容易浸透于挠性外齿轮3与外圈421之间的间隙X1，优选至少挠性外齿轮3的内周面301中的第一区域R1和外圈421的外周面424不具有防油性。
(4.4)外齿的表面状态
接下来，参照图7、图8A和图8B对本实施方式中的外齿31的表面状态进行说明。
如上所述，在本实施方式中，在外齿31设有不是通过剪切金属的晶粒的加工(滚压加工)而形成的滚压面300(第一滚压面)。因此，如图7所示，外齿31所含的滚压面300成为金属的晶粒没有被剪切、平滑的表面状态。由此，外齿31与内齿21的摩擦减少，从而因外齿31与内齿21的摩擦而引起的损失减少，难以产生谐波齿轮装置1的动力传递效率的下降。
特别是在本实施方式中，滚压面300仅设于外齿31与内齿21中的外齿31。总之，滚压面300至少设于外齿31，且表面粗糙度比内齿21小。滚压面300是通过不剪切金属的晶粒的加工(滚压加工)而形成的面，因此例如与切削加工、磨削加工或珩磨加工那样剪切金属的晶粒的加工而形成的内齿21相比，滚压面300的表面粗糙度当然变小。并且，通过将这样平滑的表面状态的滚压面300设于相对于刚性内齿轮2的内齿21如楔子那样被推压的外齿31，进一步减少外齿31与内齿21的摩擦。
另外，滚压面300仅设于挠性外齿轮3(的躯体部321)的外周面中的外齿31。也就是说，外齿31设于挠性外齿轮3的外周面，挠性外齿轮3的外周面中的除外齿31以外的部位通过例如切削加工、磨削加工或珩磨加工 那样剪切金属的晶粒的加工而形成。由此，外齿31中的滚压面300与挠性外齿轮3的外周面中的除外齿31以外的部位相比表面粗糙度小。由此，仅对挠性外齿轮3的外周面中的必要的部位实施滚压加工即可，具有提高加工性的优点。
此处，滚压面300设于外齿31与内齿21至少一者中的齿顶313、213以外的部位。也就是说，如图7所示，外齿31具有齿根312、齿顶313和齿高方向的中间部分314，而外齿31的滚压面300设于齿顶313以外的部位(齿根312和中间部分314等)。在本实施方式中，滚压面300仅为外齿31的表面中的齿根312和齿高方向的中间部分314，齿顶313例如通过切削加工、磨削加工或珩磨加工那样剪切金属的晶粒的加工而形成。因此，滚压面300即齿根312和齿高方向的中间部分314的表面与不是滚压面300的齿顶313相比表面粗糙度小。由此，滚压面300(齿根312和齿高方向的中间部分314的表面)相当于挠性外齿轮3的内周面301中的第一区域R1，不是滚压面300的齿顶313的表面相当于第二区域R2。
这样，通过将滚压面300设于齿顶313以外的部位(齿根312和中间部分314等)，容易减少外齿31与内齿21的摩擦。总之，即使是内齿21与外齿31啮合了的状态，如图7所示，也在外齿31的齿顶313与内齿21的齿根212之间确保有空隙G1。并且，外齿31利用齿顶313以外的部位(齿根312和中间部分314等)与内齿21接触，因此通过在齿顶313以外的部位设有滚压面，容易减少外齿31与内齿21的摩擦。
另外，在本实施方式中，滚压面300包含设于齿向方向D1的至少一侧的端部的齿向修整部310(参照图1B)。本公开所说的“齿向修整”是指齿向方向D1的修整，外齿31的齿向修整部310是外齿31中的实施齿向修整的部位。根据齿向修整，能够对齿轮的正规的齿向形状赋予特意的鼓起，或者改变螺旋角。作为齿向修整的代表性的加工，有凸面加工和铲齿加工(端部起伏)。凸面加工是以使齿轮的齿向方向D1的中央部为凸的方式朝 向齿向方向D1的中央部使之具有圆角的加工。铲齿加工是使齿向方向D1的两端部适度地避开的加工方法。凸面加工为朝向中央部使之具有圆角那样的遍及齿向方向D1的大致全长的加工，与此相对，铲齿加工是仅使齿向方向D1的两端部避开的加工。无论是凸面加工还是铲齿加工，都是通过使齿线方向D1的两端部的齿厚比中央部小，从而能够使与匹配齿轮的齿接触位置靠近齿线方向D1的中心附近。通过这样的齿向修整，抑制因齿轮的制作误差或组装误差而导致的齿接触偏向齿向方向D1的一端部的“单侧接触”，特别是齿向方向D1的端部(齿宽端部)处的应力集中得以缓和，齿接触得以改善。关于齿向修整部310，详情在“(4.6)齿向修整”一栏进行说明。
如将外齿31的齿根312的一部分(图7的区域Z1)放大的图8A所示，在外齿31中的、设有滚压面300的齿根312及中间部分314等处，主要成为晶粒不被剪切的平滑的表面状态。对此，如将外齿31的齿顶313的一部分(图7的区域Z2)放大的图8B所示，在没有设有滚压面300的齿顶313处，主要成为晶粒被剪切的表面状态。如图8A和图8B所示表明，在规定了齿向方向D1的单位长度W1(作为一例0.25mm)和纵向倍率的方向的单位长度Y1(作为一例1μm)的情况下，齿根312(滚压面300)的表面粗糙度比齿顶313的表面粗糙度小。
此处，滚压面300的表面粗糙度优选为齿顶313的表面粗糙度的1/64倍以上且1/10倍以下。滚压面300的表面粗糙度不限于齿顶313的表面粗糙度的1/64倍以上，例如也可以为1/80倍以上、1/50倍以上、1/30倍以上或1/16倍以上等。同样，滚压面300的表面粗糙度不限于齿顶313的表面粗糙度的1/10倍以下，例如也可以为1/2倍以下、1/5倍以下、1/12倍以下或1/16倍以下等。这样，滚压面300(齿根312和中间部分314)的表面粗糙度为与齿顶313的表面粗糙度相比足够小的值，因此在齿根312和中间部分314处容易减少与内齿21之间的摩擦。作为一例，滚压面300的表面 粗糙度优选为Ra0.01以上且Ra0.2以下，在该情况下优选齿顶313的表面粗糙度(Ra)的1/10倍以下。
即，在通过对挠性外齿轮3的外周面实施例如切削加工、磨削加工或珩磨加工那样剪切金属组织的晶粒的加工而形成的外齿31的表面，本来在晶界产生鳞状的“毛刺”(凸部)。另一方面，在通过对外齿31实施例如滚压加工那样不剪切金属组织的晶粒的加工而形成的滚压面300中，不产生这样的鳞状的“毛刺”，而实现平滑的表面状态。
另外，外齿31中的齿高方向的中间部分314的表面硬度至少比齿顶313高。具体来说，例如，利用激光淬火等能够局部地进行热处理的方法仅对外齿31的中间部分314局部地实施热处理，从而外齿31的表面硬度被局部提高。作为一例，外齿31的齿顶313的表面硬度为HRC40，而中间部分314的表面硬度为HRC60左右。
谐波齿轮装置1如果长期使用，则例如由于内齿21与外齿31的接触而可能产生因缺损或磨损等引起的金属粉或渗氮物等异物。在本实施方式中，局部提高了外齿31的表面硬度，由此，与提高挠性外齿轮3的整体的表面硬度的情况相比，不易损伤韧性，从而能够维持对挠性外齿轮3的变形的耐性。在此基础上，关于挠性外齿轮3的外齿31中的、实际能够与内齿21接触的齿高方向的中间部分314，通过提升表面硬度，能够抑制因基于与内齿21的接触产生的外齿31的缺损或磨损等而引起的金属粉或渗氮物等异物的产生。
(4.5)表面硬度
接下来，对本实施方式中的内齿21和外齿31的表面硬度进行说明。
如上所述，在本实施方式中，内齿21的表面硬度比外齿31的表面硬度低。也就是说，外齿31的表面的硬度比内齿21的表面的硬度高(硬)。本公开所说的“硬度”是指物体的坚硬程度，金属的硬度例如由以一定的压力推压钢球而形成的凹坑的大小来表示。具体而言，作为金属的硬度的 一例，有洛氏硬度(HRC)、布氏硬度(HB)、维氏硬度(HV)或肖氏硬度(Hs)等。在本实施方式中，只要没有特别否认，就是利用维氏硬度(HV)表示硬度。作为提高金属部件的硬度(变硬)的手段，例如有合金化或热处理等。
在本实施方式中，挠性外齿轮3的外齿31的表面由高硬度且高韧性(强韧)的材质构成，刚性内齿轮2的内齿21由硬度比外齿31低的材质构成。在本实施方式中，作为一例，外齿31使用对由日本产业规格(JIS：Japanese Industrial Standards)规定为“SNCM439”的镍铬钼钢实施了热处理(淬火回火)而得的材料。内齿21使用由日本产业规格(JIS)规定为“FCD800-2”的球状石墨铸铁。
进一步，与外齿31相比相对低硬度的内齿21的表面硬度优选为HV350以下。在本实施方式中，作为一例，内齿21的表面硬度在HV250以上且小于HV350的范围内进行选择。内齿21的表面硬度的下限值不限于HV250，例如也可以是HV150、HV160、HV170、HV180、HV190、HV200、HV210、HV220、HV230或HV240等。同样，内齿21的表面硬度的上限值不限于HV350，例如也可以是HV360、HV370、HV380、HV390、HV400、HV410、HV420、HV430、HV440或HV450等。
对此，与内齿21相比相对高硬度的外齿31的表面硬度优选为HV380以上。在本实施方式中，作为一例，外齿31的表面硬度在HV380以上且HV450以下的范围内进行选择。外齿31的表面硬度的下限值不限于HV380，例如也可以是HV280、HV290、HV300、HV310、HV320、HV330、HV340、HV350、HV360或HV370等。同样，内齿21的表面硬度的上限值不限于HV450，例如也可以是HV460、HV470、HV480、HV490、HV500、HV510、HV520、HV530、HV540或HV550等。
另外，在本实施方式中，内齿21的表面硬度与外齿31的表面硬度之差为HV50以上。也就是说，外齿31的表面硬度设定为比内齿21的表面 硬度高HV50以上。总之，例如，如果内齿21的表面硬度为HV350，则外齿31的表面硬度为HV400以上。另外，如果外齿31的表面硬度为HV380，则内齿21的表面硬度为HV330以下。内齿21的表面硬度与外齿31的表面硬度之差不限于HV50以上，例如也可以是HV20以上、HV30以上或HV40以上。进一步，内齿21的表面硬度与外齿31的表面硬度之差优选更大，例如，更优选为HV60以上、HV70以上、HV80以上、HV90以上或HV100以上。如果内齿21的表面硬度与外齿31的表面硬度之差为HV100以上，则在内齿21的表面硬度为HV350时，外齿31的表面硬度为HV450以上。
如上所述，在本实施方式中，内齿21的表面硬度设定为比外齿31的表面硬度更低。因此，在谐波齿轮装置1动作时，当内齿21与外齿31接触时，表面硬度相对低的内齿21比外齿31积极地磨损。在表面硬度不同的2个部件(内齿21和外齿31)接触时，相对软质的内齿21的磨损推进，由此相对硬质的外齿31的磨损被抑制。也就是说，在谐波齿轮装置1的使用初期的阶段，由于内齿21的齿面适度地磨损，所以内齿21与外齿31之间的真实接触面积扩大，面压力下降，因此难以产生外齿31的磨损。而且，在如本实施方式那样内齿21的表面硬度为HV350以下的情况下，即使通过内齿21与外齿31的接触，因内齿21的缺损或磨损等而产生异物，该异物也是比较软质的。总之，通过将容易在谐波齿轮装置1的使用初期产生的因磨损而引起的异物设为从比较软质的内齿21出来的软质异物，例如，即使异物进入轴承42也能够抑制对轴承42的损害。结果，例如，抑制对轴承42的损害大的硬质异物的产生量等。特别是当内齿21的表面硬度与外齿31的表面硬度之差如HV50以上那样为比较大的值时，上述效果显著。
进一步，通过使用球状石墨铸铁作为内齿21的材料，在内齿21的初期磨损时，能够期待抑制内齿21与外齿31的齿面烧蚀的效果。由此，能够得到内齿21与外齿31的啮合部位处的润滑效果，能够提高波动齿轮装 置1中的动力传递效率。
内齿21以及外齿31的表面硬度并非必须用维氏硬度(HV)来规定，也可以用其他硬度、例如洛氏硬度(HRC)、布氏硬度(HB)或肖氏硬度(Hs)来规定内齿21以及外齿31的表面硬度。
具体而言，在用洛氏硬度规定表面硬度的情况下，内齿21的表面硬度优选为HRC30以下。作为一例，内齿21的表面硬度在HRC20以上且小于HRC30的范围内进行选择。内齿21的表面硬度的下限值不限于HRC20、例如也可以是HRC10、HRC15或HRC25等。同样，内齿21的表面硬度的上限值不限于HRC30，例如也可以是HRC35、HRC40或HRC45等。
对此，外齿31的表面硬度优选为HRC40以上。作为一例，外齿31的表面硬度在HRC40以上且HRC60以下的范围内选择。外齿31的表面硬度的下限值不限于HRC40，例如也可以是HRC30或HRC35等。同样，外齿31的表面硬度的上限值不限于HRC60，例如也可以是HRC50、HRC55，HRC65，HRC70或HRC75等。
另外，由于挠性外齿轮3与波发生器4(轴承42的外圈421)之间的微动磨损，因缺损或磨损等而产生的异物比较硬质。也就是说，表面硬度比较高的挠性外齿轮3与轴承42的外圈421的接触而产生的异物比如上述那样从内齿21出来的软质异物硬。当从挠性外齿轮3或外圈421出来的硬质异物进入轴承42时，以异物向外圈421或内圈422与滚动体423之间的咬入而引起的压痕为起源，外圈421、内圈422以及滚动体423的任一者的表面都可能产生损伤。这样的损伤(表面起源型的剥落)导致谐波齿轮装置1的品质和特性等的恶化，因此结果会导致谐波齿轮装置1的可靠性的下降。
但是，如上所述，在本实施方式的谐波齿轮装置1中，通过将表面粗糙度小的第一区域R1设于挠性外齿轮3的内周面301中的外齿31的背侧，从而在挠性外齿轮3与波发生器4的接触部位维持充分的润滑剂Lb1。因此， 挠性外齿轮3中的与轴承42(的外圈421)的接触部位的表面成为被润滑剂Lb1覆盖的状态，能够抑制微动磨损的发生，因此原本就抑制从挠性外齿轮3或外圈421出来的音质的异物的产生。结果，例如，变得难以产生比较硬质的异物进入轴承42而引起的损伤，特别是即使长期使用时也难以产生可靠性的下降，因此，进而带来谐波齿轮装置1的传递效率的改善、寿命延长和性能提高。
(4.6)齿向修整
接下来，对本实施方式中的内齿21以及外齿31的齿向修整进行说明。
作为前提，如图1B所示，内齿21具有齿根212以及齿顶213。内齿21设置于刚性内齿轮2的内周面，因此内齿21的齿根212相当于刚性内齿轮2的内周面，齿顶213从刚性内齿轮2的内周面朝向内侧(刚性内齿轮2的中心)突出。
另一方面，如图1B所示，外齿31具有齿根312和齿顶313。外齿31设置于挠性外齿轮3(的躯体部321)的外周面，因此外齿31的齿根312相当于挠性外齿轮3(的躯体部321)的外周面，齿顶313从挠性外齿轮3(的躯体部321)的外周面朝向外侧突出。
在内齿21与外齿31的啮合位置处，外齿31的齿顶313插入内齿21的相邻的一对齿顶213之间，从而内齿21与外齿31啮合。此时，外齿31的齿顶313与内齿21的齿根212相对，内齿21的齿顶213与外齿31的齿根312相对。并且，理想的情况是，在内齿21的齿根212与外齿31的齿顶313之间、在外齿31的齿根312与内齿21的齿顶213之间，确保微小的间隙。在该状态下，内齿21和外齿31的在齿厚方向上相对的齿面彼此接触，进行刚性内齿轮2与挠性外齿轮3之间的动力传递。
进一步，内齿21在齿向方向D1的两端部具有倒角部211。倒角部211是朝向齿向方向D1的两侧减小内齿21的突出量的C面，基本上是对内齿21与外齿31的啮合没有帮助的部位。也就是说，内齿21的倒角部211在 内齿21与外齿31的啮合位置处也不与外齿31相接。同样，外齿31在齿向方向D1的两端部具有倒角部311。倒角部311是朝向齿向方向D1的两侧减小内齿21的突出量的C面，基本上是对内齿21与外齿31的啮合没有帮助的部位。也就是说，外齿31的倒角部311在内齿21与外齿31的啮合位置处也不与内齿21相接。
在此，在本实施方式中，刚性内齿轮2的内齿21具有齿向修整部210。也就是说，波动齿轮装置1至少对内齿21实施齿向修整。内齿21的齿向修整部210设置于齿向方向D1的至少一侧的端部。换言之，内齿21在内齿21的齿向方向D1的至少一侧的端部具有齿向修整部210。在本实施方式中，齿向修整部210设置于内齿21的齿向方向D1的两端部。
另外，在本实施方式中，挠性外齿轮3的外齿31也具有齿向修整部310。也就是说，谐波齿轮装置1不仅对内齿21而且对外齿31也实施齿向修整。外齿的齿向修整部210设于齿向方向D1的至少一侧的端部。换言之，外齿31在外齿31的齿向方向D1的至少一侧的端部具有齿向修整部310。在本实施方式中，齿向修整部310设于外齿31的齿向方向D1的两端部。
这样，在本实施方式的波动齿轮装置1中，内齿21和外齿31中的至少一者具有齿向修整部210、310。利用齿向修整部210、310，能够难以产生因内齿21与外齿31的过度的齿接触而引起的应力集中，结果是，能够改善该内齿21与外齿31的齿接触。由此，难以产生由内齿21与外齿31的接触产生的缺损或磨损等而引起的异物，能够实现难以产生可靠性降低的波动齿轮装置1。
(5)作用
接下来，对本实施方式的波动齿轮装置1的作用更详细地进行说明。
如上所述，在波动齿轮装置1中，特别是如果长期使用，则伴随着嵌入挠性外齿轮3的内侧的波发生器4的旋转，在挠性外齿轮3与波发生器4的接触部位可能产生微动磨损。并且，若产生微动磨损，则导致表面的粗 糙、因磨损粉而引起的生锈以及因磨损粉进入波发生器4的内侧而引起的波发生器4(的轴承42)的损伤等，可能影响谐波齿轮装置1的可靠性。
作为产生这样的微动磨损的原因，考虑是在挠性外齿轮3与波发生器4的接触部位发生了润滑剂Lb1不足或枯竭的“润滑剂耗尽”。即，推定原本挠性外齿轮3与波发生器4的接触部位处于因在润滑剂Lb1不充分的状态下产生接触面之间的微振动而容易产生微动磨损的环境。作为成为容易产生这样的微动磨损的环境的理由，具体考虑下述两个理由。
第一个理由是挠性外齿轮3频繁地反复进行弹性变形。也就是说，在波发生器4的凸轮41旋转一周期间，挠性外齿轮3反复进行2次一个方向(例如图2A的上下方向)成为椭圆形状的长轴的弹性变形。因此，通过凸轮41高速旋转，挠性外齿轮3高速地反复进行弹性变形，伴随着该弹性变形的反复进行，容易在挠性外齿轮3与波发生器4的接触部位产生振动。结果是，在挠性外齿轮3与波发生器4的接触部位，在润滑剂Lb1不充分的状态下产生微振动。
更详细地说，在挠性外齿轮3产生弹性变形的状态下，挠性外齿轮3在旋转轴Ax1的方向上的开口面35侧的端部处变形得比底部322侧的端部大，成为更接近椭圆形状的形状。因此，在挠性外齿轮3产生弹性变形的状态下，如图9所示，挠性外齿轮3的躯体部321的内周面301包括相对于旋转轴Ax1倾斜了倾斜角度θ1的渐缩面302。并且，渐缩面302的倾斜角度θ1伴随着挠性外齿轮3的弹性变形而变化。也就是说，在从开口面35侧观察挠性外齿轮3时，在椭圆形状的长轴方向的两端部，渐缩面302的倾斜角度θ1为最大(图9的“长轴侧”)，在椭圆形状的短轴方向的两端部，渐缩面302的倾斜角度θ1为最小(图9的“短轴侧”)。因此，通过挠性外齿轮3频繁地反复进行弹性变形，渐缩面302的倾斜角度θ1也高速变化，由此，挠性外齿轮3的内周面301(渐缩面302)以反复冲击外圈421的外周面424的方式振动。这样，通过产生伴随着冲击的微振动，结果 是，在挠性外齿轮3与波发生器4的接触部位容易产生微动磨损。
第二个理由是外圈421与挠性外齿轮3之间的相对旋转为低速。也就是说，由于外圈421与挠性外齿轮3之间的间隙X1的影响，与波发生器4的凸轮41旋转而外圈421和挠性外齿轮3产生弹性变形相伴随地，在外圈421与挠性外齿轮3之间可能产生相对旋转。然而，该相对旋转例如是凸轮41的转速的几千分之一或几百分之一程度的低速旋转。因此，在外圈421与挠性外齿轮3之间的间隙X1中，无法期待利用该相对旋转来使润滑剂Lb1流动，从而处于不利于在其接触部位形成由润滑剂Lb1形成的膜(油膜)的环境。尽管如此，由于在外圈421与挠性外齿轮3之间可能产生相对旋转，因此外圈421与挠性外齿轮3相对地相互摩擦，成为容易产生微动磨损的环境。
在本实施方式的谐波齿轮装置1中，根据上述那样的理由，能够将润滑剂Lb1强制地供给至处于容易产生微动磨损的环境的外圈421与挠性外齿轮3之间的接触部位。即，谐波齿轮装置1能够经由贯通孔H1将润滑剂Lb1供给至挠性外齿轮3与波发生器4接触部位，由此在接触部位维持充分的润滑剂Lb1。这样，通过防止在外圈421与挠性外齿轮3的接触部位处润滑剂Lb1不足或枯竭的“润滑剂耗尽”，从而抑制微动磨损的发生。
另外，在本实施方式的谐波齿轮装置1中，位于挠性外齿轮3的内周面301中的外齿31的背侧的第一区域R1形成为表面粗糙度比第一区域R1以外的第二区域R2小。因此，如第一区域R1那样，通过使挠性外齿轮3的内周面301成为局部平滑的表面状态，从而润滑剂Lb1容易停留于挠性外齿轮3中的与波发生器4的接触部位，在接触部位能够维持充分的润滑剂Lb1。由此，能够更进一步防止在外圈421与挠性外齿轮3的接触部位处润滑剂Lb1不足或枯竭的“润滑剂耗尽”，抑制微动磨损的发生。
其结果，外圈421与挠性外齿轮3的接触部位的表面成为被润滑剂Lb1覆盖的状态，抑制微动磨损的发生。由此，在本实施方式的谐波齿轮装置1 中，能够提供难以产生因外圈421与挠性外齿轮3之间的微动磨损而因起的不良情况，且难以产生可靠性的下降的谐波齿轮装置1。并且，本实施方式的谐波齿轮装置1即使在长期使用特之际也难以产生可靠性的下降，因此还带来谐波齿轮装置1的传递效率的改善、寿命延长和性能提高。
即，谐波齿轮装置1将润滑剂Lb1供给至外圈421与挠性外齿轮3的接触部位，因此难以阻碍挠性外齿轮3的变形追随性，并带来动力传递效率的提高和基于施加于轴承42的负载的减少的寿命延长等。进一步，还防止因微动磨损产生的磨损粉进入轴承42等情况，因此也可减少因磨损粉的咬入而引起的以压痕为起源的损伤(表面起源型的剥落)的发生。因此，作为谐波齿轮装置1可期待寿命延长和性能提高。
特别是在着眼于外圈421的周向的一部分的情况下，在仅在致动器100的外轮廓的下部存在润滑剂储存处的结构中(参照图4)，如果没有贯通孔H1，则仅在该着眼部位通过润滑剂储存处时，润滑剂Lb1才能够浸入间隙X1。并且，由于外圈421的旋转与内圈422的旋转相比为低速，因此润滑剂Lb1可浸入间隙X1的频率低。对此，在本实施方式的波动齿轮装置1中，由于设置有贯通孔H1，因此在外圈421的着眼部位通过润滑剂储存处时，仅向外圈421与内圈422之间补充润滑剂Lb1，就能够也对间隙X1供给润滑剂Lb1。也就是说，补充到外圈421与内圈422之间的润滑剂Lb1穿过贯通孔H1向间隙X1供给，因此在外圈421的整周上难以产生与挠性外齿轮3的接触部位的“润滑剂耗尽”。
另外，在本实施方式中，当轴承42动作而使多个滚动体423旋转时，滚动体423作为泵发挥功能，由此能够将润滑剂Lb1经由贯通孔H1强制地送入间隙X1。进一步，位于挠性外齿轮3的内周面301中的外齿31的背侧的第一区域R1的表面粗糙度形成得小。根据这些结构，经由贯通孔H1供给至间隙X1的润滑剂Lb1容易停留于挠性外齿轮3的内周面301，从而能够高效地消除在该间隙X1的润滑剂耗尽。进一步，挠性外齿轮3反复进 行弹性变形，渐缩面302的倾斜角度θ1高速地变化也有助于润滑剂Lb1在该间隙X1扩散。并且，不仅能够实现润滑剂耗尽的抑制，例如，还能够实现在润滑剂Lb1容易固化的低温环境下的谐波齿轮装置1的启动性的改善。
(6)应用例
接下来，参照图10对本实施方式的谐波齿轮装置1、致动器100和机器人用关节装置130的应用例进行说明。
图10是示出采用了本实施方式所涉及的谐波齿轮装置1的机器人9的一例的剖视图。该机器人9是水平多关节机器人、即所谓的柔性组合机器人臂(SCARA：Selective Compliance Assembly Robot Arm)型机器人。
如图10所示，机器人9包括2个机器人用关节装置130(包含谐波齿轮装置1)和连杆91。2个机器人用关节装置130分别设于机器人9中的2个部位的关节部。连杆91将2个部位的机器人用关节装置130连结。在图10的例子中，谐波齿轮装置1不是杯型，而是由礼帽型的波动减速装置构成。也就是说，在图10例示的谐波齿轮装置1中，采用形成为礼帽状的挠性外齿轮3。
(7)制造方法
接下来，参照图11～图16B对本实施方式的谐波齿轮装置1的制造方法进行说明。
图11是示出挠性外齿轮3的内周面301的加工的工序的概略说明图。图12A是示出挠性外齿轮3的内周面301的加工所使用的滚压辊T1和卡盘构件T2的概略剖视图，图12B是其概略侧视图。图13A是示出变形例的卡盘构件T2的概略剖视图，图13B是图13A的区域Z1的概略放大图。图14是示出挠性外齿轮3的外齿31的加工的工序的概略说明图。图15A是外齿31的加工所使用的滚刀T3的概略主视图，图15B是其概略侧视图。图16A是示出外齿31的滚压面300的加工所使用的的工具T4的概略主视 图，图16B是其概略侧视图。
(7.1)挠性外齿轮的内周面的加工
首先，对本实施方式的谐波齿轮装置1的制造方法中的、关于挠性外齿轮3的内周面301的加工的方法进行说明。
如图11所示，本实施方式的谐波齿轮装置1的制造方法具有准备工序(工序P11)和塑性加工工序(工序P13)。准备工序是准备成为挠性外齿轮3的基础的基材3A的工序。塑性加工工序是在基材3A的内周面301通过塑性加工形成第一区域R1的工序。即，在本制造方法中，作业者首先在准备工序中准备具有内周面301的筒状的基材3A。基材3A的内周面301例如通过对金属构件的切削加工、磨削加工或珩磨加工而形成。也就是说，在准备工序中准备的基材3A的内周面301与第二区域R2同样，内周面301的整个区域处于金属的晶粒被剪切的表面状态。
然后，作业者在塑性加工工序中，通过对基材3A的内周面301的一部分实施塑性加工，从而形成在内周面301包含第一区域R1(滚压面)和第二区域R2(切削面)的挠性外齿轮3。在本实施方式中，作为一例，在塑性加工工序进行的塑性加工是使用滚压辊T1的滚光加工。滚光加工是滚压加工的一种，用滚压辊T1的辊T12(参照图12A)将金属表面压平从而形成光滑的表面状态。也就是说，在塑性加工工序中，在使高硬度的金属制的辊T12压接于基材3A的内周面301的状态下，以在内周面301上滚动的方式使辊T12沿内周面301的周向移动，由此使内周面301塑性变形，形成第一区域R1。
更详细地说，在塑性加工工序中使用如图12A和图12B所示那样的滚压辊T1。图12A相当于图12B的A1-A1线剖面。滚压辊T1具有：主轴部T11，构成为能够以中心轴Ax3为中心旋转(自转)；和多个辊T12，保持于主轴部T11的外周部。多个(此处作为一例为8个)辊T12在主轴部T11的周向上等间隔地配置。各辊T12形成为圆柱状，并以能够以与中心轴Ax3 平行的中心轴Ax4为中心旋转(自转)的状态保持于主轴部T11。在将这样的滚压辊T1插入基材3A内的状态下，通过以中心轴Ax3为中心(在图12B的例子中为逆时针方向)旋转驱动主轴部T11，由此多个辊T12分别以中心轴Ax4为中心(在图12B的例子中为顺时针方向)旋转。此时，与基材3A的内周面301相接的多个辊T12以在内周面301上滚动的方式一边移动一边进行滚压(图11的工序P13)。根据这样的塑性加工工序，不仅能够形成平滑的表面状态的第一区域R1，还能够期待耐磨耗性的提升和疲劳强度的提高等表面改性。
另外，在本实施方式中，还具有至少在塑性加工工序时，用卡盘构件T2从外周面侧卡紧基材3A的卡紧工序(工序P12)。由此，在辊T12被推压于基材3A的内周面301的状态下，能够抑制基材3A自身向外周侧扩展的变形，从而能够高效地进行对内周面301的滚压。
如图12A和图12B所示，卡盘构件T2整体上形成为在与中心轴Ax3平行的方向的两侧开口的圆筒状。卡盘构件T2具有在周向上连续一体地形成的本体部T21和在周向上被分割成多个的多个单片T22。多个单片T22与本体部T21的轴向的一侧的端缘(在图12A为右端缘)连接。多个单片T22以与本体部T21的连结部为支点向中心轴Ax3侧挠曲，由此被多个单片T22包围的部位的内径缩小。因此，如图11所示，从卡盘构件T2中的多个单片T22侧插入基材3A(工序P11)，之后，通过从外侧紧固多个单片T22，卡盘构件T2从外周侧卡紧基材3A。
然后，在从外周面侧利用卡盘构件T2卡紧(保持)筒状的基材3A的状态下，将滚压辊T1插入于基材3A内，并以轴Ax3为中心旋转滚压辊T1(工序P13)。在通过塑性加工(滚光加工)形成第一区域R1之后，从基材3A内拔出滚压辊T1，且解除多个单片T22的紧固，由此解除卡盘构件T2对基材3A的卡紧(工序P14)。在该状态下，能够从卡盘构件T2取出基材3A。
另外，在本实施方式中，在塑性加工工序中，没有形成挠性外齿轮3的外周面的外齿31。也就是说，图11所示的基材3A处于没有形成外齿31的状态。关于用于形成外齿31的工序，详情在“(7.2)外齿的加工”一栏中进行说明。即，本实施方式的谐波齿轮装置1的制造方法在塑性加工工序之后还具有在基材3A的外周面形成外齿31的工序。由此，在外齿31的背侧的位置形成第一区域R1的塑性加工工序中，能够避免在外齿31产生变形等不良情况的发生。
在形成外齿31之后，有对基材3A实施例如喷丸硬化加工或形成化成被膜的表面处理等的情况。在喷丸硬化加工中，通过投射小的球状投射材料对表面赋予改性硬化，能够实现挠性外齿轮3的疲劳强度的提高。优选在进行这些喷丸硬化加工或表面处理等之际，对滚压加工后的基材3A的内周面(特别是第一区域R1)进行养护(掩蔽)。由此，滚压加工后的基材3A的内周面不易受到喷丸硬化加工或表面处理等的影响。
另外，在本实施方式中，通过旋转驱动滚压辊T1(的主轴部T11)，进行塑性加工，但不限于此，只要在滚压辊T1的主轴部T11与基材3A之间产生相对的旋转就可以。例如，也可以在固定了滚压辊T1的主轴部T11的状态下，通过旋转驱动卡盘构件T2，使基材3A相对于滚压辊T1的主轴部T11相对旋转，由此进行塑性加工。
另外，如图13A和图13B所示，卡盘构件T2也可以具有与基材3A的外周面对应的形状的内周面T221。图13A和图13B所示的卡盘构件T2的多个单片T22的内周面T221形成为沿着切齿前、也就是外齿31形成前的基材3A的外周面的形状的形状。具体而言，如图13B所述，在切齿前的基材3A的外周面且在开口面35侧设有膨胀部31A。该膨胀部31A设于基材3A的周向的整个区域，形成为比其他部位壁厚。并且，多个单片T22的内周面T221具有与该膨胀部31A对应的形状的凹陷，在用卡盘构件T2卡紧基材3A的状态下，膨胀部31A嵌于该凹陷。
即，在图13A和图13B的例子中，卡盘构件T2具有与基材3A的外周面对应的形状的内周面T221，且构成为能够在周向上分割为多个单片T22。根据该结构，在塑性加工工序中，能够遍及基材3A的外周面的整个区域利用卡盘构件T2承受来自滚压辊T1的滚压力。因此，例如对挠性外齿轮3的躯体部321与外齿31的边界部分也施加因滚压而产生的压缩残留应力。也就是说，除挠性外齿轮3的外齿31部分之外，关于躯体部321部分也由滚压加工面构成内周面301，能够实现至少对外齿31与躯体部321的边界部分也施加因滚压加工而产生的压缩残留应力的结构。由此，使挠性外齿轮3薄壁且在压缩残留应力的作用下改善韧性(提高容许应力)，能够维持对挠性外齿轮3的变形的耐性。
(7.2)外齿的加工
接下来，对本实施方式的谐波齿轮装置1的制造方法中的、关于挠性外齿轮3的外齿31的加工的方法进行说明。
如图14所示，本实施方式的谐波齿轮装置1的制造方法具有工序P21、工序P22和工序P23。工序P21是准备成为挠性外齿轮3的基础的(第二)基材3A的工序。工序P22是在(第二)基材3A形成外齿31的工序。工序P23是在外齿31通过塑性加工形成滚压面300的工序。即，在该制造方法中，作业者首先在工序P21中准备具有膨胀部31A的基材3A。在本实施方式中，在工序P21准备的(第二)基材3A处于在上述塑性加工工序中对内周面301实施了塑性加工(滚压加工)而形成第一区域R1的状态。然后，在工序P22中，例如通过切削加工、磨削加工或珩磨加工等在膨胀部31A形成外齿31。也就是说，在工序P23形成滚压面300之前的基材3A的外齿31与第二区域R2同样，外齿31的整个区域处于金属的晶粒被剪切的表面状态。
另外，在实施方式中，由于在外齿31形成(第一)滚压面300，因此制造方法具有上述工序P21～P22(参照图14)，但是如其他实施方式那样， 在内齿21形成(第二)滚压面200的情况下，工序P21～P23置换为如下。即，工序P21为准备成为刚性内齿轮2的基础的第一基材的工序。工序P22为在第一基材形成内齿21的工序。工序P23为在内齿通过塑性加工形成滚压面200的工序。
此处，在第一基材形成内齿21的工序和在(第二)基材3A形成外齿31的工序P22中的至少一者包含切削加工。具体而言，内齿21和外齿31通过使用旋转驱动滚刀T3的滚刀盘的切齿加工(滚刀加工)而形成。也就是说，在基材3A形成外齿31的工序P22中，如图14所示，作业者通过利用滚刀盘以中心轴Ax5为中心旋转驱动被推压于基材3A的膨胀部31A的滚刀T3，切削膨胀部31A从而形成外齿31。此时，伴随着滚刀T3的旋转，基材3A也以旋转轴Ax1为中心旋转，由此遍及基材3A的外周面的整周形成外齿31。
更详细地说，在工序P22中，使用如图15A和图15B那样的、滚刀T3。滚刀T3具有构成为能够以中心轴Ax5为中心旋转(自转)的圆筒部T31和从圆筒部T31的外周面突出的多个刃部T32。多个刃部T32以成为以中心轴Ax5为中心的螺旋状的方式排列成一列进行配置。在图14、图15A和图15B中，用假想线(双点划线)表示由多个刃部T32构成的列(刃列)的外形，省略一部分的刃部T32的图示。在将这样的滚刀T3的多个刃部T32推压于基材3A的膨胀部31A的状态下，一边使基材3A以旋转轴Ax1为中心旋转，一边利用滚刀盘以中心轴Ax5为中心(在图15B的例子中为顺时针)旋转驱动圆筒部T31。此时，通过滚刀T3的刃部T32切削基材3A膨胀部31A，以与中心轴Ax5平行的方向上的多个刃部T32的间距同等的间距形成外齿31(图14的工序P22)。
另外，根据基于这样的切削加工(滚刀加工)的切齿，虽然形成外齿31，但是该外齿31的表面与第二区域R2相同，其整个区域成为金属的晶粒被剪切的表面状态。也就是说，在外齿31的表面产生与滚刀T3的进给 量等对应的鳞状的刀痕。在本实施方式中，在工序P22后的工序P23中，通过塑性加工在外齿31形成滚压面300，由此将这样的产生作为刀痕的凹凸的外齿31的表面压平，从而实现平滑的表面状态。
具体而言，在工序P23中，塑性加工使用如图16A和图16B所示那样的工具T4，该工具T4具有与切削加工所使用的滚刀T3相同的间距的肋T42。工具T4具有构成为能够以中心轴Ax5为中心旋转(自转)的圆筒部T41和从圆筒部T41的外周面突出的肋T42。肋T42形成为以中心轴Ax5为中心的螺旋状。此处，圆筒部T41具有与滚刀T3的圆筒部T31相同的形状，肋T42具有与由滚刀T3的多个刃部T32构成的列(刃列)的外形相同的形状。也就是说，工具T4相当于去掉滚刀T3的刃部T32的形状，且能够代替滚刀T3装配于滚刀盘。
在将这样的工具T4的肋T42推压于基材3A的外齿31的状态下，一边使基材3A以旋转轴Ax1为中心旋转，一边利用滚刀盘以中心轴Ax5为中心(在图16B的例子中为顺时针)旋转驱动圆筒部T41。此时，在工具T4的肋T42压接于外齿31的状态下，使外齿31的表面产生塑性变形，形成滚压面300(图14的工序P23)。由此，连同在切齿时产生的刀痕一起因晶粒的剪切而产生的晶界被压扁，从而实现平滑的表面状态的滚压面300。结果是，对于作业者而言，使用工具T4代替滚刀T3，仅进行与滚刀加工同样的滚刀盘的操作就能够在外齿31容易地形成滚压面300。
另外，工具T4通过进行与滚刀T3同样的动作而在外齿31形成滚压面300，因此能够通过滚压进行凸面加工或铲齿加工(端部起伏)等加工。由此，能够容易实现包含齿向修整部310的滚压面300。
(7.3)其他
在制造本实施方式的谐波齿轮装置1之际，特别是在制造外圈421时，优选实施避免因设置贯通孔H1而导致的强度下降的对策。
作为一例，在形成贯通孔H1的开孔工序后，进行对外圈421(特别是 成为滚动面的内周面425)进行表面加工的表面加工工序。也就是说，为了避免贯通孔H1成为外圈421的割裂的起源，优选在外圈421中的贯通孔H1周边残留压缩残留应力。因此，优选在对外圈421进行淬火等表面加工工序之前，形成贯通孔H1，并残留基于热处理而产生的压缩残留应力。或者，也可以在热处理后对外圈421的贯通孔H1周边实施投射小的球状投射材材料对表面赋予改性硬化的喷丸硬化加工等，由此提高外圈421的疲劳强度。
(8)变形例
上述实施方式只不过是本公开的各种实施方式的一种。实施方式只要能够实现本公开的目的，就可以根据设计等进行各种变更。另外，本公开参照的附图都是示意性的图，图中的各结构要素的大小及厚度各自的比未必反映实际的尺寸比。以下，列举实施方式的变形例。以下说明的变形例可以适当组合适用。
贯通孔H1也可以处于在与旋转轴Ax1平行的方向(齿向方向D1)上从多个滚动体423的中心偏离的位置。作为一例，贯通孔H1配置于从滚动体423的中心向开口面35侧偏离的位置，也就是配置于在齿向方向D1上滚动体423的中心与开口面35之间的位置。根据该结构，具有以下优点：即使从滚动体423对形成有贯通孔H1的构件(此处为外圈421)沿径向方向施加大的负载，该负载也难以作用于贯通孔H1的周边，难以产生以贯通孔H1为起源的割裂等。
另外，贯通孔H1也可以在与旋转轴Ax1平行的方向(齿向方向D1)上设于多个部位。另外，在径向方向上，贯通孔H1的间隙X1侧的开口面积也可以比与间隙X1相反一侧的开口面积小。即，在设于外圈421的(第一)贯通孔H1中，成为间隙X1侧的外周面424侧的贯通孔H1的开口面积比成为与间隙X1相反一侧的内周面425侧的贯通孔H1的开口面积小。由此，能够提高通过贯通孔H1供给至间隙X1的润滑剂Lb1的压力。
图17A和图17B示出实施方式的变形例，与图1A和图1B相当的剖视图。在图17A和图17B所示的谐波齿轮装置1A中，(第二)贯通孔H2设于挠性外齿轮3的外齿31。换言之，在本变形例中，贯通孔H2包含设于挠性外齿轮3的外齿31的“第二贯通孔”。设于挠性外齿轮3的外齿31部分的贯通孔H2、也就是设于在旋转轴Ax1方向上与轴承42对应的部位的贯通孔H2沿着径向方向贯通挠性外齿轮3。由此，贯通孔H2的一侧的开口面面向外圈421与挠性外齿轮3之间的间隙X1，贯通孔H2的另一侧的开口面在挠性外齿轮3的外齿31中的成为与内齿21的啮合面的外周面开口。因此，贯通孔H2的一端与外圈421和挠性外齿轮3之间的间隙X1相连，另一端与外齿31和内齿21之间的空间相连。因此，外齿31与内齿21之间的空间经由贯通孔H2与外圈421和挠性外齿轮3之间的间隙X1连通。由此，处于外齿31与内齿21之间的空间的润滑剂Lb1能够通过贯通孔H2供给至外圈421与挠性外齿轮3之间的间隙X1。
在挠性外齿轮3相对于刚性内齿轮2相对旋转时，外齿31的一部分与内齿21啮合，因此外齿31和内齿21作为泵发挥功能。也就是说，外齿31和内齿21构成泵。在本变形例中，通过外齿31与内齿21啮合，提高外齿31与内齿21之间的空间内的压力，因此处于外齿31与内齿21之间的润滑剂Lb1通过贯通孔H2被挤出至间隙X1侧。这样，外齿31和内齿21构成叶片泵那样容积型的泵，以充分的压力将润滑剂Lb1挤出至间隙X1侧，因此容易将充分的润滑剂Lb1供给至间隙X1内。
此处，如图17B所示，(第二)贯通孔H2在与旋转轴Ax1平行的方向(齿向方向D1)上位于外齿31中的中心与开口面35侧的端部之间。另外，(第二)贯通孔H2配置于外齿31的齿根312和齿顶313中的齿顶313。由此，与在齿根312形成有贯通孔H2的情况相比，通过在齿顶313形成有贯通孔H2，难以产生以贯通孔H2为起源的割裂等。
另外，贯通孔H1、H2也可以设于外圈421和挠性外齿轮3的外齿31 双方。在该情况下，处于轴承42的外圈421与内圈422之间的空间的润滑剂Lb1能够通过贯通孔H1供给至外圈421与挠性外齿轮3之间的间隙X1。进一步，处于外齿31与内齿21之间的空间的润滑剂Lb1能够通过贯通孔H2供给至外圈421与挠性外齿轮3之间的间隙X1。因此，能够将润滑剂Lb1从径向方向的两侧(内侧和外侧)供给至间隙X1。此处，优选在(第一)贯通孔H1与(第二)贯通孔H2中，内齿21的在齿向方向D1上的位置不同。
另外，对内齿21和外齿31实施齿形修整并不是谐波齿轮装置1必不可少的结构。例如，也可以对内齿21与外齿31的至少一者不实施齿形修整。
另外，在径向方向上，在多个滚动体423的轨道与设于外圈421的(第一)贯通孔H1的开口面之间确保有规定值以上的距离并不是谐波齿轮装置1必不可少的结构。也就是说，也可以在滚动体423存在于与贯通孔H1对应的位置的状态下，在贯通孔H1的开口面与滚动体423之间不产生间隙，由滚动体423封闭贯通孔H1。
另外，在轴承42中，各滚动体423被4点支承也不是谐波齿轮装置1必不可少的结构，例如，也可以是各滚动体423被2点支承的结构。
另外，谐波齿轮装置1不限于实施方式所说明的杯型，例如，也可以是礼帽型、环型、差动型、扁平型(薄饼型)或盾牌型等。例如，即使是图10所例示那样的礼帽型的谐波齿轮装置1，与杯型同样，也具有在齿向方向D1的一侧具有开口面35的筒状的挠性外齿轮3。也就是说，礼帽状的挠性外齿轮3在旋转轴Ax1的一侧的端部具有凸缘部，在与凸缘部相反一侧的端部具有开口面35。即使是礼帽状的挠性外齿轮3，在开口面35侧的端部也具有外齿31，且嵌入有波发生器4。
另外，致动器100的结构也不限于实施方式中说明的结构，可以进行适当的改变。例如，关于输入部103与凸轮41的连结结构，不限于花键连 结结构，也可以使用十字头联轴器等。通过使用十字头联轴器作为输入部103与凸轮41的连结结构，能够抵消输入侧的旋转轴Ax1与波发生器4(凸轮41)之间的偏心，进一步能够抵消刚性内齿轮2与挠性外齿轮3的偏心。进一步，凸轮41也可以不能相对于输入部103沿着旋转轴Ax1移动。
另外，本实施方式的谐波齿轮装置1、致动器100和机器人用关节装置130的应用例不限于如上所述的水平多关节机器人，例如也可以是水平多关节机器人以外的工业用机器人或者是工业用以外的机器人等。在水平多关节机器人以外的产业用机器人中，作为一例，存在垂直多关节型机器人或平行连杆型机器人等。在产业用以外的机器人中，作为一例，有家庭用机器人、护理用机器人或医疗用机器人等。
另外，轴承42不限于深沟球轴承，例如也可以是角接触球轴承等。进一步，轴承42不限于球轴承，例如也可以是滚动体423由不是滚珠状的“滚子”构成的、圆筒滚子轴承、针状滚子轴承或圆锥滚子轴承等滚子轴承。即使是这样的滚珠状(球体状)以外的滚动体423，也会因滚动体423转动而产生压力差，滚动体423作为泵结构发挥功能。
另外，谐波齿轮装置1、致动器100或机器人用关节装置130的各结构要素的材质不限于金属，例如也可以是工程塑料等树脂。
另外，润滑剂Lb1不限于润滑油(油液)等液态的物质，也可以是润滑脂等凝胶态的物质。
另外，贯通孔H1的数量和配置不限于实施方式所说明的数量和配置。例如，贯通孔H1也可以设置1个、2个或4个以上。进一步，在设有多个贯通孔H1的情况下，多个贯通孔H1的间隔P1也可以是多个滚动体423的间隔P2的倍数，多个贯通孔H1配置为等间距也不是必不可少的。
另外，挠性外齿轮3的内周面301的加工所使用的滚压辊T1和卡盘构件T2不限于上述的结构，能够进行适当变更。同样，关于外齿31的加工所使用的滚刀T3和工具T4也不限于上述的结构，能够进行适当变更。作 为一例，也可以以滚刀T3的由多个刃部T32构成的列(刃列)从其中途切换至工具T4的肋T42的方式使得滚刀T3与工具T4一体化。
如图18A、图18B和图18C所示，本实施方式的谐波齿轮装置1B在滚压面200设于刚性内齿轮2的内齿21这一方面与上述实施方式的谐波齿轮装置1不同。以下，关于与实施方式1同样的结构，标注相同的附图标记而适当省略说明。图18A是图2B的区域Z1的放大概略图。图18B是表示图18A的区域Z1中的内齿21的表面状态的概略图，图18C是表示图18A的区域Z2中的内齿21的表面状态的概略图。
即，在本实施方式中，滚压面200仅设于外齿31与内齿21中的内齿21。换言之，在本实施方式中，滚压面200是设于刚性内齿轮2的内齿21的“第二滚压面”。关于(第二)滚压面200，也与上述实施方式的(第一)滚压面300相同，通过不剪切金属的晶粒的加工(滚压加工)来形成。
另外，在设于内齿21的滚压面200(第二滚压面)中，也与外齿31的滚压面300(第一滚压面)相同，优选在齿顶213以外的部位(齿根212等)设置滚压面300。也就是说，如将内齿21的齿根212的一部分(图18A的区域Z1)放大的图18B所示，在内齿21中的设有滚压面200的齿根212等处，主要成为晶粒不被剪切的平滑的表面状态。对此，如将内齿21的齿顶213的一部分(图18A的区域Z2)放大的图18C所示，在没有设有滚压面200的齿顶213处，主要成为晶粒被剪切的表面状态。并且，表明齿根212(滚压面200)的表面粗糙度比齿顶213的表面粗糙度小。
如本实施方式那样，即使是在内齿21设有滚压面200的结构，由于外齿31与内齿21的摩擦减少，因此因外齿31与内齿21的摩擦而引起的损失也减少，从而难以产生谐波齿轮装置1B的动力传递效率的下降。另外，由于抑制因摩擦引起的表面的粗糙又或是生锈，因此也难以阻碍挠性外齿轮3的变形追随性，波发生器4的旋转不容易需要额外的能量，从而抑制动力传递效率的下降。结果是，能够提供难以产生动力传递效率的下降的 谐波齿轮装置1B。
作为实施方式的变形例，滚压面200、300设于内齿21和外齿31两者。
本实施方式的结构(包含变形例在内)可以与上述实施方式所说明的结构(包含变形例在内)适当组合来应用。
(总结)
如上所说明，第一方式的谐波齿轮装置(1、1A、1B)包括刚性内齿轮(2)、挠性外齿轮(3)和波发生器(4)。刚性内齿轮(2)是具有内齿(21)的环状的部件。挠性外齿轮(3)是具有外齿(31)且配置于刚性内齿轮(2)的内侧的环状的部件。波发生器(4)具有：非圆形状的凸轮(41)，以旋转轴(Ax1)为中心被旋转驱动；和轴承(42)，装配于凸轮(41)的外侧。波发生器(4)配置于挠性外齿轮(3)的内侧，并使挠性外齿轮(3)产生挠曲。谐波齿轮装置(1、1A、1B)伴随着凸轮(41)的旋转而使挠性外齿轮(3)变形，使外齿(31)的一部分与内齿(21)的一部分啮合，从而使挠性外齿轮(3)根据与刚性内齿轮(2)的齿数差而相对于刚性内齿轮(2)进行相对旋转。外齿(31)与内齿(21)的至少一者包含滚压面(300、200)。
根据该方式，由于外齿(31)与内齿(21)的摩擦减少，因此因外齿(31)与内齿(21)的摩擦而引起的损失减少，从而难以产生谐波齿轮装置(1、1A、1B)的动力传递效率的下降。另外，由于抑制了基于摩擦的表面粗糙、又或是生锈，因此也难以阻碍挠性外齿轮(3)的变形追随性，波发生器(4)的旋转不容易需要额外的能量，从而抑制动力传递效率的下降。结果是，能够提供难以产生动力传递效率的下降的谐波齿轮装置(1、1A、1B)。
根据第一方式，在第二方式的谐波齿轮装置(1、1A、1B)中，滚压面(300、200)设于外齿(31)和内齿(21)的至少一者中的除齿顶(313、213)以外的部位。
根据该方式，容易减少外齿(31)与内齿(21)的摩擦。
根据第一或第二方式，在第三方式的谐波齿轮装置(1、1A、1B)中，滚压面(300、200)包含设于齿向方向(D1)的至少一侧的端部的齿向修整部(310、210)。
根据该方式，齿向方向(D1)的端部(齿宽端部)处的应力集中得到缓和，齿接触得以改善。
根据第一～第三中任一项的方式，在第四方式的谐波齿轮装置(1、1A、1B)中，滚压面(300)至少设于外齿(31)，且滚压面的表面粗糙度比内齿(21)小。
根据该方式，容易减少外齿(31)与内齿(21)的摩擦。
根据第一～第四中任一项的方式，在第五方式的谐波齿轮装置(1、1A、1B)中，滚压面(300)仅设于挠性外齿轮(3)的外周面中的外齿(31)。
根据该方式，只要对挠性外齿轮(3)的外周面中的必要的部位实施滚压加工即可，具有提高加工性的优点。
第六方式的谐波齿轮装置(1、1A、1B)的制造方法是第一～第五中任一项的方式的谐波齿轮装置(1、1A、1B)的制造方法，具有：准备成为刚性内齿轮(2)的基础的第一基材的工序；准备成为挠性外齿轮(3)的基础的第二基材(3A)的工序；在第一基材形成内齿(21)的工序；在第二基材(3A)形成外齿(31)的工序；和在外齿(31)和内齿(21)的至少一者通过塑性加工形成滚压面(300、200)的工序。
根据该方式，能够提供一种外齿(31)与内齿(21)的摩擦减少且难以产生动力传递效率的下降的谐波齿轮装置(1、1A、1B)。
根据第六方式，在第七方式的谐波齿轮装置(1、1A、1B)的制造方法中，在第一基材形成内齿(21)的工序和在第二基材(3A)形成外齿(31)的工序的至少一者包含切削加工。
根据该方式，能够缩短内齿(21)与外齿(31)的形成所需要的时间。
根据第七方式，在第八方式的谐波齿轮装置(1、1A、1B)的制造方法中，塑性加工使用具有与切削加工所使用的滚刀(T3)相同间距的肋(T42)的工具(T4)来进行。
根据该方式，使用工具(T4)代替滚刀(T3)，仅进行与滚刀加工同样的滚刀盘的操作就能够容易地形成滚压面(300、200)。
第九方式的机器人用关节装置(130)包括：第一～第五中任一方式的谐波齿轮装置(1、1A、1B)；固定于刚性内齿轮(2)的第一构件(131)；和固定于挠性外齿轮(3)的第二构件(132)。
根据该方式，能够提供一种外齿(31)与内齿(21)的摩擦减少且难以产生动力传递效率的下降的机器人用关节装置(130)。
第十方式的齿轮部件用作第一～第五中任一方式的谐波齿轮装置(1、1A、1B)的刚性内齿轮(2)或挠性外齿轮(3)。
根据该方式，能够提供一种外齿(31)与内齿(21)的摩擦减少且难以产生动力传递效率的下降的齿轮部件。
关于第二～第五方式的结构，不是谐波齿轮装置(1、1A、1B)必不可少的结构，能够适当省略。关于第七或第八方式的结构，不是谐波齿轮装置(1、1A、1B)的制造方法必不可少的结构，能够适当省略。
附图标记说明
1、1A、1B 谐波齿轮装置
2 刚性内齿轮(齿轮部件)
3 挠性外齿轮(齿轮部件)
3A (第二)基材
4 波发生器
21 内齿
31 外齿
41 凸轮
42 轴承
130 机器人用关节装置
131 第一构件
132 第二构件
200 (第二)滚压面
300 (第一)滚压面
210、310 齿向修整部
213、313 齿顶
Ax1 旋转轴
D1 齿向方向
T3 滚刀
T4 工具
T42 肋
工业实用性
根据本公开实施例，能够提供一种难以产生动力传递效率下降的谐波齿轮装置、谐波齿轮装置的制造方法、机器人用关节装置和齿轮部件。

Claims (10)

  1. 一种谐波齿轮装置，包括：
    环状的刚性内齿轮，具有内齿；
    环状的挠性外齿轮，具有外齿并配置于所述刚性内齿轮的内侧；和
    波发生器，具有以旋转轴为中心被旋转驱动的非圆形状的凸轮、和装配于所述凸轮的外侧的轴承，所述波发生器配置于所述挠性外齿轮的内侧，使所述挠性外齿轮产生挠曲，
    伴随着所述凸轮的旋转而使所述挠性外齿轮变形，使所述外齿的一部分与所述内齿的一部分啮合，从而使所述挠性外齿轮按照与所述刚性内齿轮的齿数差而相对于所述刚性内齿轮进行相对旋转，其中，
    所述外齿与所述内齿的至少一者包含滚压面。
  2. 根据权利要求1所述的谐波齿轮装置，其中，
    所述滚压面设于所述外齿和所述内齿的至少一者中的除齿顶以外的部位。
  3. 根据权利要求1或2所述的谐波齿轮装置，其中，
    所述滚压面包含设于齿向方向的至少一侧的端部的齿向修整部。
  4. 根据权利要求1～3中任一项所述的谐波齿轮装置，其中，
    所述滚压面至少设于所述外齿，且所述滚压面的表面粗糙度比所述内齿小。
  5. 根据权利要求1～4中任一项所述的谐波齿轮装置，其中，
    所述滚压面仅设于所述挠性外齿轮的外周面中的所述外齿。
  6. 一种谐波齿轮装置的制造方法，是权利要求1～5中任一项所述的谐波齿轮装置的制造方法，其中，所述制造方法具有：
    准备成为所述刚性内齿轮的基础的第一基材的工序；
    准备成为所述挠性外齿轮的基础的第二基材的工序；
    在所述第一基材形成所述内齿的工序；
    在所述第二基材形成所述外齿的工序；和
    在所述外齿和所述内齿的至少一者通过塑性加工形成所述滚压面的工序。
  7. 根据权利要求6所述的谐波齿轮装置的制造方法，其中，
    在所述第一基材形成所述内齿的工序和在所述第二基材形成所述外齿的工序的至少一者包含切削加工。
  8. 根据权利要求7所述的谐波齿轮装置的制造方法，其中，
    所述塑性加工使用具有与所述切削加工所使用的滚刀相同间距的肋的工具来进行。
  9. 一种机器人用关节装置，其中，包括：
    权利要求1～5中任一项所述的谐波齿轮装置；
    第一构件，固定于所述刚性内齿轮；和
    第二构件，固定于所述挠性外齿轮。
  10. 一种齿轮部件，其中，所述齿轮部件用作权利要求1～5中任一项所述的谐波齿轮装置的所述刚性内齿轮或所述挠性外齿轮。
PCT/CN2022/099475 2021-10-25 2022-06-17 谐波齿轮装置、谐波齿轮装置的制造方法、机器人用关节装置和齿轮部件 WO2023071231A1 (zh)

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