Flexible mesh gear device and manufacturing method thereof

Abstract

To provide a deflective meshing type gear device capable of improving durability of an inner-ring-side rolling surface of a vibration generating body bearing, and a method for manufacturing a deflective meshing type gear device.SOLUTION: A deflective meshing type gear device (1) includes a vibration generating body (10A), an external tooth gear (12) which is deflectively deformed by the vibration generating body, an internal tooth gear (22g, 23g) which meshes with the external tooth gear, and a vibration generating body bearing (15) disposed between the vibration generating body and the external tooth gear. A hardening treatment is applied to an inner-ring-side rolling surface on which rolling elements (15A) of the vibration generating body bearing (15) roll. The hardening treatment is the treatment for imparting the inner-ring-side rolling surface with a characteristic that the surface hardness of the inner-ring-side rolling surface after operation for a predetermined time becomes higher than the surface hardness of the inner-ring-side rolling surface before the operation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a flexible mesh gear device and a method for manufacturing a flexible mesh gear device. [Background technology]

[0002] Patent Document 1 shows a flexible mesh gear device including a vibration exciter, an external gear that is flexibly deformed by the vibration exciter, an internal gear that meshes with the external gear, and a vibration exciter bearing disposed between the vibration exciter and the external gear. In the flexible mesh gear device, when the vibration exciter having a non-circular cross section rotates, the external gear rotates relatively via the vibration exciter bearing, and the external gear flexibly deforms around the vibration exciter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-091444 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a flexible mesh gear device, the inner ring rolling surface of the vibration exciter bearing is under severe conditions in terms of durability, and it is desirable to improve the durability thereof.

[0005] An object of the present invention is to provide a flexible mesh gear device capable of improving the durability of the inner ring rolling surface. [Means for solving the problem]

[0006] A flexible mesh gear device according to one aspect of the present invention comprises: A flexible meshing gear device including a vibration exciter, an external gear that is flexibly deformed by the vibration exciter, an internal gear that meshes with the external gear, and a vibration exciter bearing disposed between the vibration exciter and the external gear, The rolling elements of the vibration exciter bearing roll on an inner ring-side rolling surface that has been subjected to a hardening treatment, The inner ring rolling surface has a characteristic that the surface hardness after the flexible mesh gear device is operated for a predetermined time is higher than the surface hardness before the operation. death, The inner ring side rolling surface includes a major axis position and a minor axis position in a cross-sectional outline perpendicular to the central axis, and further includes a portion in which the surface hardness at the major axis position is higher than the surface hardness at the minor axis position at the same axial position after the predetermined time of operation. .

[0007] Another embodiment of the flexible mesh gear device of the present invention is A flexible meshing gear device including a vibration exciter, an external gear that is flexibly deformed by the vibration exciter, an internal gear that meshes with the external gear, and a vibration exciter bearing disposed between the vibration exciter and the external gear, The rolling elements of the vibration exciter bearing roll on an inner ring-side rolling surface that has been subjected to a hardening treatment, The inner ring rolling surface has a characteristic that, after the flexible mesh gear device is operated for a predetermined time, the surface hardness of a rolling portion of the inner ring rolling surface with which the rolling elements come into contact is higher than the surface hardness of a non-rolling portion with which the rolling elements do not come into contact. death, The inner ring side rolling surface includes a major axis position and a minor axis position in a cross-sectional outline perpendicular to the central axis, and further includes a portion in which the surface hardness at the major axis position is higher than the surface hardness at the minor axis position at the same axial position after the predetermined time of operation. .

[0008] A method for manufacturing a flexible mesh gear device according to one aspect of the present invention includes the steps of: A manufacturing method of a flexible mesh gear device including a vibration exciter, an external gear that is flexibly deformed by the vibration exciter, an internal gear that meshes with the external gear, and a vibration exciter bearing disposed between the vibration exciter and the external gear, comprising: a hardening treatment step of hardening an inner ring-side rolling surface on which the rolling elements of the vibration exciter bearing roll, In the hardening treatment step, a treatment is performed to impart to the inner ring rolling surface a property such that the surface hardness of the inner ring rolling surface after the flexible mesh gear device has been operated for a predetermined time is higher than the surface hardness of the inner ring rolling surface before the operation. stomach, The inner ring side rolling surface includes a major axis position and a minor axis position in a cross-sectional outline perpendicular to the central axis, and further includes a portion in which the surface hardness at the major axis position is higher than the surface hardness at the minor axis position at the same axial position after the predetermined time of operation. .

[0009] A method for manufacturing a flexible mesh gear device according to another aspect of the present invention includes the steps of: A manufacturing method of a flexible mesh gear device including a vibration exciter, an external gear that is flexibly deformed by the vibration exciter, an internal gear that meshes with the external gear, and a vibration exciter bearing disposed between the vibration exciter and the external gear, comprising: a hardening treatment step of hardening an inner ring-side rolling surface on which the rolling elements of the vibration exciter bearing roll, In the hardening treatment step, after the flexible mesh gear device is operated for a predetermined time, a treatment is performed to impart to the inner ring side rolling surface a property such that the surface hardness of a rolling portion of the inner ring side rolling surface with which the rolling elements come into contact is higher than the surface hardness of a non-rolling portion with which the rolling elements do not come into contact. stomach, The inner ring side rolling surface includes a major axis position and a minor axis position in a cross-sectional outline perpendicular to the central axis, and further includes a portion in which the surface hardness at the major axis position is higher than the surface hardness at the minor axis position at the same axial position after the predetermined time of operation. . Effect of the Invention

[0010] According to the present invention, it is possible to provide a flexible mesh gear device in which the durability of the inner ring side rolling surface of the vibration exciter bearing is improved, and a manufacturing method for a flexible mesh gear device. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing a flexible mesh gear device according to a first embodiment of the present invention. [Diagram 2] 2A is a perspective view showing the vibrator axis in FIG. 1, and FIG. 2B is a cross-sectional view perpendicular to the vibration exciter's rotation axis. [Diagram 3] 4 is a time chart showing an example of a heat treatment for hardening the vibrator shaft. [Figure 4] FIG. 5 is a cross-sectional view showing a flexible mesh gear device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0013] Fig. 1 is a cross-sectional view showing a flexible mesh gear device according to a first embodiment of the present invention. In the following, the direction along the rotation axis O1 in Fig. 1 is called the axial direction, the direction perpendicular to the rotation axis O1 is called the radial direction, and the direction of rotation about the rotation axis O1 is called the circumferential direction. Furthermore, in the axial direction, the side of the second cover 27 where the reduced rotational motion is output is called the output side, and the opposite side is called the anti-output side.

[0014] The flexible mesh gear device 1 in Fig. 1 is a cylindrical flexible mesh gear device in which an external gear 12 is flexibly deformed and a rotational motion is transmitted at a reduced speed. The flexible mesh gear device 1 includes a vibration exciter shaft 10, an external gear 12 that is flexibly deformed by the vibration exciter shaft 10, a counter-output side internal gear 22 and an output side internal gear 23 that mesh with the external gear 12, and a vibration exciter bearing 15. The flexible mesh gear device 1 further includes a casing 24, a first cover 26, a second cover 27, input bearings 31, 32, and a main bearing 33. The output side internal gear 23 corresponds to the first internal gear according to the present invention. The counter-output side internal gear 22 corresponds to the second internal gear according to the present invention.

[0015] The vibrator shaft 10 is a hollow shaft, and includes a vibrator 10A having an elliptical cross section perpendicular to the rotation axis (center axis) O1, and shaft portions 10B and 10C provided on both sides of the axial direction of the vibrator 10A and having a circular cross section perpendicular to the rotation axis O1. Note that the elliptical shape is not limited to a strict geometric ellipse, but includes an approximate ellipse. The vibrator shaft 10 rotates around the rotation axis O1, and the center of the outer shape of the vibrator 10A in a cross section perpendicular to the rotation axis O1 coincides with the rotation axis O1. The vibrator shaft 10 is an input shaft that is connected to a driving source such as a motor (not shown) and receives a driving force. In the first embodiment, the outer peripheral surface of the vibrator 10A corresponds to an inner ring side rolling surface on which the rolling elements of the vibrator bearing 15 roll.

[0016] The external gear 12 is a cylindrical flexible metal member having teeth on its outer periphery.

[0017] The vibrator bearing 15 is disposed between the vibrator 10A and the external gear 12. The vibrator bearing 15 has a plurality of rolling elements 15A, a retainer 15C that holds the plurality of rolling elements 15A, and an outer ring 15B. The rolling elements 15A are rollers, but may be balls. The plurality of rolling elements 15A include a plurality of rolling elements 15A on the counter-output side located radially inward of one of the internal teeth 22g, and a plurality of rolling elements 15A on the output side located radially inward of the other internal teeth 23g. The plurality of rolling elements 15A roll with the outer peripheral surface of the vibrator 10A as the inner ring side rolling surface and the inner peripheral surface of the outer ring 15B as the outer ring side rolling surface. The rolling surface is also called a raceway surface.

[0018] The counter-output side internal gear 22 and the output side internal gear 23 have internal teeth 22g, 23g on their inner circumferences, respectively. One internal teeth 22g meshes with teeth on the counter-output side from the axial center of the external gear 12, and the other internal teeth 23g meshes with teeth on the output side from the axial center of the external gear 12. The counter-output side internal gear 22 and the external gear 12 have different numbers of teeth, and the output side internal gear 23 and the external gear 12 have the same number of teeth. Note that the gear with the same number of teeth may be referred to as the counter-output side internal gear 22, and the gear with the different number of teeth may be referred to as the output side internal gear 23.

[0019] The casing 24 is connected to the counter-output side internal gear 22 and covers the radial outside of the internal teeth portions 22g, 23g and the external gear 12 together with the counter-output side internal gear 22. The first cover 26 is connected to the output side internal gear 23 and covers the outer periphery on the counter-output side of the vibration exciter shaft 10. The second cover 27 is connected to the counter-output side internal gear 22 and covers the outer periphery on the output side of the vibration exciter shaft 10. The first cover 26 rotatably supports the vibration exciter shaft 10 via an input bearing 31. The second cover 27 rotatably supports the vibration exciter shaft 10 via an input bearing 32. The casing 24 rotatably supports the output side internal gear 23 via a main bearing 33.

[0020] <Operation description> When the vibrator shaft 10 is rotated by a driving source such as a motor, the motion of the vibrator 10A is transmitted to the external gear 12. At this time, the external gear 12 is restricted to a shape that conforms to the outer circumferential surface of the vibrator 10A, and is bent into an elliptical shape having a major axis portion and a minor axis portion when viewed from the axial direction. Furthermore, the external gear 12 is meshed with the fixed counter-output side internal gear 22 at the major axis portion. Therefore, the external gear 12 does not rotate at the same rotation speed as the vibrator 10A, and the vibrator 10A rotates relatively inside the external gear 12. Then, with this relative rotation, the external gear 12 is bent and deformed so that the major axis position and the minor axis position move in the circumferential direction. The period of this deformation is proportional to the rotation period of the vibrator shaft 10.

[0021] When the external gear 12 flexes and deforms, the position of its major axis moves, causing the meshing position between the external gear 12 and the counter-output side internal gear 22 to change in the rotational direction. For example, if the number of teeth of the external gear 12 is 100 and the number of teeth of the counter-output side internal gear 22 is 102, then the meshing teeth of the external gear 12 and the counter-output side internal gear 22 shift each time the meshing position makes one revolution, causing the external gear 12 to rotate (spin on its axis). With the above number of teeth, the rotational motion of the vibration exciter shaft 10 is decelerated at a reduction ratio of 100:2 and transmitted to the external gear 12.

[0022] Meanwhile, since the external gear 12 also meshes with the output side internal gear 23, the meshing position between the external gear 12 and the output side internal gear 23 also changes in the rotational direction due to the rotation of the vibration exciter shaft 10. If the number of teeth of the output side internal gear 23 and the number of teeth of the external gear 12 are the same, the external gear 12 and the output side internal gear 23 do not rotate relative to each other, and the rotational motion of the external gear 12 is transmitted to the output side internal gear 23 at a reduction ratio of 1:1. As a result, the rotational motion of the vibration exciter shaft 10 is decelerated at a reduction ratio of 100:2 and transmitted to the output side internal gear 23 and the second cover 27, and this rotational motion is output to an external member to be driven.

[0023] <Details of the vibrator shaft> 2A is a perspective view showing the vibrator shaft, and FIG. 2B is a cross section perpendicular to the rotation axis of the vibrator. As explained above, the outer peripheral surface of the vibrator 10A corresponds to the inner ring side rolling surface on which the rolling elements 15A of the vibrator bearing 15 roll. The material of the vibrator shaft 10 is steel, and more specifically, it is steel containing 0.18 to 0.23 weight percent of C (carbon), 0.15 to 0.35 weight percent of Si (silicon), 0.60 to 0.90 weight percent of Mn (manganese), 0.030 weight percent or less of P (phosphorus), 0.030 weight percent or less of S (sulfur), 0.25 weight percent or less of Ni (nickel), 0.90 to 1.20 weight percent of Cr (chromium), and 0.15 to 0.25 weight percent of Mo (molybdenum).

[0024] As shown in FIG. 2(A), the outer peripheral surface of the vibrator 10A includes a rolling area H1 on the anti-output side with which the rolling element 15A on the anti-output side comes into contact, a rolling area H2 on the output side with which the rolling element 15A on the output side comes into contact, and a non-rolling area H3 with which the rolling element 15A does not come into contact. In FIG. 2(A), the boundaries between the areas H1 to H3 are indicated by two-dot chain lines. The non-rolling area H3 is located at the center and both ends in the axial direction of the inner wheel side rolling surface. Furthermore, as shown in FIG. 2(B), the outer peripheral surface of the vibrator 10A includes a major axis range W1, which is a range around the major axis position P1 (for example, a range of ±70 degrees from the major axis position P1), and a minor axis range W2, which is a range around the minor axis position P2 (for example, a range of ±20 degrees from the minor axis position P2). The major axis position P1 is the maximum radius position on the outer periphery of the ellipse in a cross section of the vibrator 10A cut perpendicularly to the rotation axis O1, and the minor axis position P2 is the minimum radius position on the outer periphery of the ellipse in the same cross section. The rolling contact area H1 is located radially inside the internal teeth portion 22g of the counter-output side internal gear 22 and corresponds to the second portion in the present invention. The rolling contact area H2 is located radially inside the internal teeth portion 23g of the output side internal gear 23 and corresponds to the first portion in the present invention.

[0025] The outer peripheral surface (inner ring side rolling surface) of the vibrator 10A has different contact surface pressures with the rolling element 15A at various points. Naturally, the rolling areas H1 and H2 have a higher contact surface pressure with the rolling element 15A than the non-rolling area H3. The major axis range W1 has a higher contact surface pressure with the rolling element 15A than the minor axis range W2, and the output side rolling area H2 has a higher contact surface pressure with the rolling element 15A than the anti-output side rolling area H1. Note that a configuration is also possible in which the output side rolling area H2 has a lower contact surface pressure with the rolling element 15A than the anti-output side rolling area H1.

[0026] <Hardening treatment> The vibrator shaft 10 is hardened as a single component. The hardening process is a process that imparts to the inner raceway a property that makes the hardness of the inner raceway surface higher after a specified period of operation than the hardness of the inner raceway surface before operation. The above-mentioned operation means that a load is applied to a (new) flexible mesh gear device 1 incorporating the vibrator shaft 10 to cause it to decelerate. The above-mentioned hardening process is achieved by the following heat treatment.

[0027] FIG. 3 is a time chart showing an example of a heat treatment for hardening the vibrator shaft. In this heat treatment, first, the vibrator shaft 10 before hardening is heated in a furnace to 950°C to 980°C, and when it is uniformly heated to this temperature, the atmosphere in the furnace is switched to a hydrocarbon gas (e.g., methane, propane, ethylene, acetylene, etc.) at that temperature, and this state is maintained, and then it is cooled (first heat step J1). Next, the vibrator shaft 10 is heated in a furnace to 850°C, and when it is uniformly heated to this temperature, the atmosphere in the furnace is switched to the above-mentioned hydrocarbon gas at that temperature, and this state is maintained, and then it is cooled (second heat step J2). Next, the vibrator shaft 10 is heated in a furnace to 880°C, and when it is uniformly heated to this temperature, the atmosphere in the furnace is switched to NH3 gas at that temperature, and this state is maintained, and then it is cooled to a temperature lower than that of the first heat step J1 and the second heat step J2 (third heat step J3). Thereafter, tempering is performed at 160° C. to 180° C. for several hours (fourth thermal process J4), and the hardening treatment is completed.

[0028] By setting the temperature of the first thermal process J1 to a high temperature, a certain degree of hardening depth can be obtained in a short time. However, if the temperature is increased beyond 980°C, adverse effects such as coarsening of crystal grains are likely to occur, so the temperature of the first thermal process J1 is set to 950°C to 980°C. Note that the hardening treatment that imparts the above-mentioned characteristics is not limited to the above-mentioned heat treatment.

[0029] The above heat treatment causes carbon and nitrogen to penetrate and diffuse into the surface of the vibrator shaft 10, and martensite transformed during the cooling process and untransformed retained austenite are distributed on the surface. The surface of the vibrator shaft 10 then obtains the properties shown in the following Table 1. [Table 1] Here, ECD is the effective case depth, which in this embodiment indicates the depth from the surface to a Vickers hardness of 550 HV, for example. Residual γ indicates the volume ratio of retained austenite to the total volume. Carbide amount indicates the area ratio of precipitated carbides in the cross section of the surface portion.

[0030] The combination of these surface characteristics realizes a characteristic that the hardness of the outer peripheral surface (inner ring side rolling surface) of the vibrator 10A after operation for a predetermined time is higher than that before operation. In general, in the inner ring side rolling surface of any bearing on which rolling elements roll, rolling fatigue occurs on the inner ring side rolling surface due to repeated load fluctuations applied by the rolling elements. When the rolling fatigue reaches its fatigue life, damage such as flaking and pitting originating from the surface occurs. One of the causes of such damage is thought to be a decrease in hardness of the metal surface. On the other hand, according to the outer peripheral surface of the vibrator 10A having a characteristic that the hardness increases after operation for a predetermined time by hardening treatment, the hardness of the inner ring side rolling surface of the vibrator bearing 15 increases during operation of the flexible mesh gear device 1. Therefore, damage such as flaking and pitting caused by a decrease in hardness is suppressed, and the durability of the inner ring side rolling surface of the vibrator bearing 15, which is under severe conditions in terms of durability, is improved. As a result, the life of the flexible mesh gear device 1 can be extended.

[0031] The characteristic of hardness increasing by operation for a predetermined time may be, for example, a characteristic in which the hardness of the inner ring rolling surface becomes higher than before operation when the rated load (maximum torque) is applied and the operation is performed for 10,000 revolutions or more under operating conditions of a rotation speed that is 50 to 80 percent of the rated rotation speed (average is about 6.5 percent of the rated rotation speed). This characteristic improves the durability of the inner ring rolling surface of the vibrator bearing 15, which is under severe conditions in terms of durability, and can extend the life of the flexible mesh gear device 1.

[0032] The characteristic of hardness increasing with operation for a predetermined time may preferably be a characteristic in which the hardness increases by 5% or more before and after the operation of 10,000 revolutions. Furthermore, the above characteristic may more preferably be a characteristic in which the hardness at 10,000 revolutions is maintained at ±3% or more of the hardness at 10,000 revolutions from 20,000 revolutions to 50,000 revolutions under the above operating conditions. Furthermore, the above characteristic may even more preferably be a characteristic in which the hardness gradually increases from 10,000 revolutions to 50,000 revolutions under the above operating conditions. Such a characteristic can extend the life of the flexible mesh gear device 1.

[0033] The characteristic of hardness increasing by operation for a predetermined time is a characteristic of hardness increasing by rolling the rolling element 15A on the outer peripheral surface (inner ring side rolling surface) of the vibrator 10A while applying a load. Therefore, the characteristic of hardness increasing by operation for a predetermined time may be a characteristic that appears only in the part of the outer peripheral surface of the vibrator 10A where the contact surface pressure of the rolling element 15A is large, not in the entire area of ​​the outer peripheral surface of the vibrator 10A. In other words, it may be a characteristic that appears in the rolling part H2 on the output side where the contact surface pressure is high, or in the long axis range W1 of the rolling parts H1 and H2. Note that the entire angle range of the long axis range W1 does not have a characteristic of hardness increasing before and after operation, but only a part of the angle range of the long axis range W1 may have a characteristic of hardness increasing before and after operation. Furthermore, the non-rolling part H3 does not receive contact surface pressure from the rolling element 15A, and the change in hardness before and after operation is small. Therefore, the characteristic of hardness increasing with operation for a predetermined time can be rephrased as the characteristic that the hardness of the rolling contact portions H1, H2 becomes higher than the hardness of the non-rolling contact portion H3 when the rolling contact portion H2 is operated for a predetermined time.

[0034] Furthermore, the rate of increase in hardness is higher in the portion where the contact surface pressure of the rolling element 15A is large. That is, the rate of increase in hardness before and after operation is higher in the output side rolling portion H2 than in the anti-output side rolling portion H1, and the rate of increase in hardness before and after operation is higher in the major axis range W1 than in the minor axis range W2.

[0035] <How to check for increased hardness> Next, we will explain how to confirm the characteristic of hardness increasing with operation of the above-mentioned hardened vibrator shaft 10. The characteristics of the outer circumferential surface of the vibrator 10A change slightly each time it receives a load from the rolling elements 15A, but the increase in hardness can be easily identified when it is operated under the following conditions. Operating condition 1: Apply rated load (maximum torque) and operate 10,000 times continuously at 50-80% of the rated rotation speed (average is about 6.5% of the rated rotation speed).

[0036] For the flexible mesh gear device 1 of embodiment 1, the vibrator shaft 10 was removed and the hardness of each part of the vibrator 10A was measured at the time of shipment (when new) and after operation under operating condition 1, and the measurement results shown in the following table were obtained.

[0037] [Table 2] In the table, "anti-output side of long axis" refers to rolling area H1 in long axis range W1 (see Figure 2), and "anti-output side of short axis" refers to rolling area H1 in short axis range W2. "Output side of long axis" refers to rolling area H2 in long axis range W1, and "output side of short axis" refers to rolling area H2 in short axis range W2. "Non-rolling area" refers to non-rolling area H3. "Hardness" refers to Vickers hardness with a test force of 300gf (1gf ≒ 9.8mN).

[0038] As shown in measurement result 1, the hardness of the outer peripheral surface of vibrator 10A increases after operation in rolling contact areas H1 and H2 that receive a load from rolling element 15A compared to before operation. Furthermore, the rate of increase in hardness in major axis range W1, where the contact pressure with rolling element 15A is high, is higher than the rate of increase in hardness in minor axis range W2, and the rate of increase in hardness in output side rolling contact area H2, where the contact pressure with rolling element 15A is high, is higher than the rate of increase in hardness in anti-output side rolling contact area H1. Since non-rolling contact area H3 does not receive a load from rolling element 15A during operation, the change in hardness is small and is equivalent to the hardness of rolling contact areas H1 and H2 before operation.

[0039] As described above, according to the flexible mesh gear device 1 of the first embodiment, the inner ring rolling surface of the vibrator bearing 15, i.e., the outer circumferential surface of the vibrator 10A, is hardened. Furthermore, this hardening process is a process that imparts to the inner ring rolling surface a property that the surface hardness after a predetermined time of operation is higher than the hardness before operation. In other words, the hardening process is a process that imparts to the inner ring rolling surface a property that the surface hardness of the rolling parts H1 and H2 after a predetermined time of operation is higher than the surface hardness of the non-rolling part H3. This hardening process increases the hardness of the outer circumferential surface of the vibrator 10A during the operation of the flexible mesh gear device 1, and damage such as flaking and pitting caused by a decrease in hardness can be suppressed. Therefore, the durability of the flexible mesh gear device 1 can be improved.

[0040] Furthermore, according to the flexible mesh gear device 1 of the first embodiment, the portion of the outer circumferential surface of the vibrator 10A where the hardness increases due to operation is included in the long axis range W1. The long axis range W1 receives a high contact surface pressure from the rolling element 15A compared to other regions, and is in a severe state in terms of durability. Therefore, the hardness of this portion increases due to operation, improving durability, and thus the durability of the flexible mesh gear device 1 can be further improved. Note that it is not necessary for the entire long axis range W1 to have a higher hardness after operation than before operation, and it is sufficient that a part of the long axis range W1 has a higher hardness after operation than before operation. Preferably, it is sufficient that the hardness of the range of the long axis range W1 where durability is in a severe state increases, and durability is improved.

[0041] Furthermore, according to the flexible mesh gear device 1 of the first embodiment, the portion of the outer circumferential surface of the vibrator 10A whose hardness increases with operation includes the rolling area H2 on the output side. In the configuration of the first embodiment, the rolling area H2 on the output side receives a higher contact pressure from the rolling elements 15A than the rolling area H1 on the counter-output side, and is in a severe state in terms of durability. Therefore, the hardness of this portion increases with operation, improving durability, and thus the durability of the flexible mesh gear device 1 can be further improved. Note that, in the case where the rolling area H1 on the counter-output side receives a higher contact pressure from the rolling elements 15A than the rolling area H2 on the output side, the portion whose hardness increases with operation may include the rolling area H2 on the counter-output side.

[0042] Furthermore, according to the flexible mesh gear device 1 of the first embodiment, the hardening treatment of the vibrator shaft 10 is a treatment in which the residual austenite is 35 to 45% by volume and the amount of carbide is 5 to 15% by area on the outer peripheral surface of the vibrator 10A. Due to such phase transformation and composition of the surface, the hardness increases during operation, making it easy to realize the characteristics of the surface that improve durability.

[0043] (Embodiment 2) 4 is a cross-sectional view showing a flexible mesh gear device according to embodiment 2 of the present invention. The flexible mesh gear device 1A of embodiment 2 is different in that the vibrator bearing 15 has an inner ring 15D, and other components are the same as those of embodiment 1. In embodiment 2, the vibrator shaft 10 may or may not be subjected to a hardening treatment.

[0044] The inner ring 15D has an elliptical outer peripheral shape in a cross section perpendicular to the rotation axis (center axis) O1. Specifically, the inner ring 15D has a perfect circular shape before being fitted around the vibrator 10A, and becomes elliptical when fitted around the vibrator 10A. The elliptical shape is not limited to a geometrically strict ellipse, but includes an approximate ellipse. The inner ring 15D is fitted around the vibrator 10A of the vibrator shaft 10 and rotates together with the vibrator 10A. The outer peripheral surface of the inner ring 15D is an inner ring side rolling surface on which the rolling elements 15A roll. The outer peripheral surface of the inner ring 15D includes a rolling portion on the counter-output side with which the rolling elements 15A come into contact, a rolling portion on the output side, and a non-rolling portion, similar to the outer peripheral surface of the vibrator 10A of the first embodiment, and also includes a major axis region and a minor axis region in the circumferential direction, similar to the outer peripheral surface of the vibrator 10A of the first embodiment.

[0045] The material of the inner ring 15D is the same as that of the vibrator bearing 15 of the first embodiment.

[0046] The inner ring 15D is hardened as a single component. The hardening treatment is similar to the hardening treatment applied to the vibrator bearing 15 of embodiment 1. The properties, phase transformation and composition imparted to the inner ring 15D by the hardening treatment, as well as the hardness of each part before and after a predetermined period of operation, are similar to those imparted to the outer circumferential surface of the vibrator 10A of embodiment 1.

[0047] In the flexible mesh gear device 1A of the second embodiment, the outer circumferential surface of the inner ring 15D of the vibrator bearing 15 receives a large load from the rolling elements 15A and is in a severe state in terms of durability. According to the flexible mesh gear device 1A of the second embodiment, the hardness of the outer circumferential surface of the inner ring 15D increases during the operation of the flexible mesh gear device 1A, and damage such as flaking and pitting caused by a decrease in hardness can be suppressed. Therefore, the durability of the flexible mesh gear device 1A can be improved. In addition, the flexible mesh gear device 1A of the second embodiment also achieves the same effects as those described in the first embodiment. In the explanation of the effects of the first embodiment, the effects of the second embodiment can be shown by replacing the outer circumferential surface of the vibrator 10A with the outer circumferential surface of the inner ring 15D.

[0048] The above describes each embodiment of the present invention. However, the present invention is not limited to the above embodiment. For example, the heat treatment for realizing the hardening treatment described in the embodiment is only one example, and the present invention is not limited thereto. Various heat treatments can be applied as long as a treatment for imparting to the inner ring side rolling surface a property that the surface hardness of the inner ring side rolling surface after a predetermined time of operation is higher than the surface hardness of the inner ring side rolling surface before operation, or a treatment for imparting to the inner ring side rolling surface a property that the surface hardness of the rolling portion of the inner ring side rolling surface with which the rolling elements contact is higher than the surface hardness of the non-rolling portion with which the rolling elements do not contact, after a predetermined time of operation, can be realized. In addition, in the above embodiment, a so-called cylindrical flexible mesh gear device is shown, but the present invention is not limited thereto, and can also be applied to so-called cup type, top hat type, and other flexible mesh gear devices. The present invention can also be considered as a manufacturing method for a flexible mesh gear device having a hardening treatment process for performing the above-mentioned hardening treatment on the inner ring side rolling surface on which the rolling elements of the vibration exciter bearing roll. In addition, the details shown in the embodiment can be modified as appropriate without departing from the spirit of the invention. [Explanation of symbols]

[0049] 1, 1A Flexible meshing gear device 10 Vibration axis 10A vibrator H1 rolling part (second part) H2 rolling part (1st part) H3 Non-rolling part W1 Long axis range W2 Minor axis range 12 External gear 15 Vibrator bearing 15A rolling element 15B Outer ring 15D Inner ring 22 Non-output side internal gear (second internal gear) 22g Internal teeth 23 Output side internal gear (first internal gear) 23g Internal teeth 31, 32 Input bearing 33 Main bearing

Claims

1. A flexible meshing gear device including a vibration exciter, an external gear that is flexibly deformed by the vibration exciter, an internal gear that meshes with the external gear, and a vibration exciter bearing disposed between the vibration exciter and the external gear, The rolling elements of the vibration exciter bearing roll on an inner ring-side rolling surface that has been subjected to a hardening treatment, the inner ring rolling surface has a characteristic that a surface hardness thereof after the flexible mesh gear device has been operated for a predetermined time is higher than a surface hardness thereof before the operation, the inner ring side rolling surface includes a major axis position and a minor axis position in a cross-sectional outline perpendicular to the central axis, and further includes a portion where a surface hardness at the major axis position is higher than a surface hardness at the minor axis position at the same axial position after the predetermined time of operation. Flexible mesh gear system.

2. A flexible meshing gear device including a vibration exciter, an external gear that is flexibly deformed by the vibration exciter, an internal gear that meshes with the external gear, and a vibration exciter bearing disposed between the vibration exciter and the external gear, The rolling elements of the vibration exciter bearing roll on an inner ring-side rolling surface that has been subjected to a hardening treatment, the inner ring side rolling surface has a characteristic that, after the flexible mesh gear device is operated for a predetermined time, the surface hardness of a rolling portion of the inner ring side rolling surface with which the rolling elements come into contact is higher than the surface hardness of a non-rolling portion with which the rolling elements do not come into contact, the inner ring side rolling surface includes a major axis position and a minor axis position in a cross-sectional outline perpendicular to the central axis, and further includes a portion where a surface hardness at the major axis position is higher than a surface hardness at the minor axis position at the same axial position after the predetermined time of operation. Flexible mesh gear system.

3. The portion in which the surface hardness is increased after the predetermined period of operation is included in a range of ±70 degrees from the major axis position of the inner ring rolling surface.

3. The flexible mesh gear device according to claim 1 or 2.

4. The internal gear includes a first internal gear and a second internal gear, a contact surface pressure between the inner ring side rolling surface and the rolling elements is greater in a first portion located radially inside of the first internal gear than in a second portion located radially inside of the second internal gear, The surface hardness of the first portion after the predetermined time of operation is higher than that of the second portion. The flexible mesh gear device according to any one of claims 1 to 3.

5. the inner ring rolling surface has a retained austenite content of 35 to 45 volume % and a carbide content of 5 to 15 area % before operation of the flexible mesh gear device; The flexible mesh gear device according to any one of claims 1 to 4.

6. A manufacturing method of a flexible mesh gear device including a vibration exciter, an external gear that is flexibly deformed by the vibration exciter, an internal gear that meshes with the external gear, and a vibration exciter bearing disposed between the vibration exciter and the external gear, comprising: a hardening treatment step of hardening an inner ring-side rolling surface on which the rolling elements of the vibration exciter bearing roll, the hardening treatment step comprises a treatment for imparting to the inner ring side rolling surface a property such that the surface hardness of the inner ring side rolling surface after the flexible mesh gear device has been operated for a predetermined time is higher than the surface hardness of the inner ring side rolling surface before the operation; the inner ring side rolling surface includes a major axis position and a minor axis position in a cross-sectional outline perpendicular to the central axis, and further includes a portion where a surface hardness at the major axis position is higher than a surface hardness at the minor axis position at the same axial position after the predetermined time of operation. A method for manufacturing a flexure mesh gear device.

7. A manufacturing method of a flexible mesh gear device including a vibration exciter, an external gear that is flexibly deformed by the vibration exciter, an internal gear that meshes with the external gear, and a vibration exciter bearing disposed between the vibration exciter and the external gear, comprising: a hardening treatment step of hardening an inner ring-side rolling surface on which the rolling elements of the vibration exciter bearing roll, the hardening treatment step comprises, after operating the flexible mesh gear device for a predetermined time, providing the inner ring side rolling surface with a property such that the surface hardness of a rolling portion of the inner ring side rolling surface with which the rolling elements come into contact is higher than the surface hardness of a non-rolling portion with which the rolling elements do not come into contact, the inner ring side rolling surface includes a major axis position and a minor axis position in a cross-sectional outline perpendicular to the central axis, and further includes a portion where a surface hardness at the major axis position is higher than a surface hardness at the minor axis position at the same axial position after the predetermined time of operation. A method for manufacturing a flexure mesh gear device.

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