CN111594582A

CN111594582A - Flexural engagement gear device and method for manufacturing same

Info

Publication number: CN111594582A
Application number: CN201911369079.4A
Authority: CN
Inventors: 吉田真司; 石塚正幸
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2019-02-21
Filing date: 2019-12-26
Publication date: 2020-08-28
Anticipated expiration: 2039-12-26
Also published as: DE102020102403A1; JP2020133800A; JP2023054008A; DE102020102403B4; CN111594582B; JP7374361B2; JP7438666B2

Abstract

The invention aims to optimize the hardness of an internal gear member. A flexible meshing gear device (1) is provided with: a vibrator (10A); an external gear (12) which is deformed by the deflection of the vibration generating body; an internal gear (23g) that meshes with the external gear; and a main bearing (33) for supporting the internal gear, wherein the internal gear member (23) provided with the internal gear is provided with internal teeth on the inner periphery thereof and integrally provided with an inner ring rolling surface (334) of the main bearing on the outer periphery thereof, and the internal gear member has, in order from the inner ring rolling surface toward the internal teeth: rolling surface hardness parts (H11, H21); a sharp hardness drop part (H12, H22) where the hardness drops sharply from the rolling surface hardness part; and hardness increasing portions (H13, H23) in which the hardness increases and the absolute value of the slope of the change in hardness is smaller than the absolute value of the slope of the change in hardness in the sharply decreasing portion.

Description

Flexural engagement gear device and method for manufacturing same

The present application claims priority based on japanese patent application No. 2019-029798, applied on 21/2/2019. The entire contents of this Japanese application are incorporated by reference into this specification.

Technical Field

The present invention relates to a flexible engagement gear device and a method of manufacturing the same.

Background

Conventionally, there is a flexible mesh type gear device including an external gear that is flexible and deformable (for example, refer to patent document 1). The external gear is configured to be fitted with a vibration generator via a vibration generator bearing and to be deformed by being rotated inside. Also, the external gear meshes with the internal gear having rigidity.

In such a flex-mesh type gear device, an inner ring of a bearing for supporting an output and an input of a decelerated rotation is integrated with an internal gear, and the number of components is reduced.

Patent document 1: japanese patent laid-open publication No. 2017-106626

As described above, in a component in which an internal gear and an inner ring of a bearing are integrated (hereinafter, referred to as an internal gear component), there are cases where the hardness required for the tooth surface portion of the internal gear and the inner ring of the bearing are different, and therefore it is desirable to optimize the hardness according to the component position.

Disclosure of Invention

The purpose of the present invention is to optimize the hardness of an internal gear member.

The present invention provides a flexible meshing gear device comprising:

a vibration starting body; an external gear which is deformed by the vibration generator; an internal gear engaged with the external gear; and a main bearing supporting the internal gear, wherein,

an internal gear member provided with the internal gear is formed with internal teeth on an inner periphery thereof and integrally provided with an inner ring rolling surface of the main bearing on an outer periphery thereof,

the internal-tooth member is configured to have, in order from the inner ring rolling surface toward the internal teeth: a rolling surface hardness section; a rapid hardness decrease portion from which hardness decreases rapidly; and a hardness increasing portion in which the hardness increases and an absolute value of a slope of a change in hardness is smaller than an absolute value of a slope of a change in hardness of the hardness sharply decreasing portion.

In the method of manufacturing a flexible mesh gear device according to the present invention, the flexible mesh gear device includes: a vibration starting body; an external gear which is deformed by the vibration generator; an internal gear engaged with the external gear; and a main bearing supporting the internal gear, wherein the method for manufacturing the flex-mesh gear device comprises the steps of:

a groove forming step of forming a groove for forming an inner ring rolling surface on an outer periphery of a material for forming an inner gear member in which inner teeth of the inner gear are formed on an inner periphery and the inner ring rolling surface of the main bearing is integrally provided on an outer periphery;

a 1 st heat treatment step of performing a 1 st heat treatment on the forming material in a state where a thickness is left at a position radially inward of a position where the internal teeth are formed;

a 2 nd heat treatment step of performing the 2 nd heat treatment on the groove of the forming material for forming the inner ring rolling surface in a state where a thickness is left at a position radially inward of a position where the internal teeth are formed after the 1 st heat treatment step; and

and an inner peripheral surface forming step of removing the thickness at a position radially inward of a position where the internal teeth are formed, after the 2 nd heat treatment step.

According to the present invention, the hardness of the internal gear member can be optimized.

Drawings

Fig. 1 is a sectional view showing a flexible engagement gear device according to an embodiment of the present invention.

Fig. 2 is an enlarged cross-sectional view showing a peripheral portion of the internal gear member.

Fig. 3 is a graph showing a hardness distribution in the radial direction of the internal gear member.

Fig. 4 (a) to (D) are explanatory views showing the respective steps of the method for manufacturing an internal gear member in this order.

Fig. 5 (a) to (C) are explanatory views sequentially showing steps of the internal gear member manufacturing method shown in fig. 4.

In the figure: 1-flexure meshing type gear device, 10-vibration-starting-body shaft, 10A-vibration-starting body, 12-external gear, 22g, 23 g-internal gear, 23M-metal block (forming material), 33-main bearing, 231M-through hole, 232M-V groove, 233M-inner peripheral surface, 234, 235-adjacent inner peripheral surface, 331-inner ring, 332-outer ring, 333-rolling body, 334, 335-inner ring rolling surface, H11, H21-rolling surface hardness portion, H12, H22-hardness sharp-decreasing portion, H13, H23-hardness increasing portion, O1-rotation shaft, P-middle point.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[ Flexible engagement type Gear device ]

Fig. 1 is a sectional view showing a flexible engagement gear device 1 according to an embodiment of the present invention. In the present specification, a direction along the rotation axis O1 is defined as an axial direction, a direction orthogonal to the rotation axis O1 is defined as a radial direction, and a rotation direction around the rotation axis O1 is defined as a circumferential direction.

As shown in fig. 1, the flexible mesh gear device 1 includes: an oscillation start shaft 10; an external gear 12 which is deformed by the oscillation starting body shaft 10; two

internal gears

22g, 23g meshing with the external gear 12; and a starting vibration body bearing 15. The flexible meshing gear device 1 further includes a 1 st housing 22, an internal gear member 23, a 2 nd housing 24, a 1 st cover 26, a 2 nd cover 27, a bearing 31, a bearing 32, a main bearing 33, a sealing O-ring 34, a sealing O-ring 35, a sealing O-ring 38, an oil seal 41, an oil seal 42, and an oil seal 43.

The oscillation starting body shaft 10 is in the form of a hollow shaft, and includes: the external shape of the section of the oscillator 10A perpendicular to the rotation axis O1 is an ellipse; and

shaft portions

10B and 10C provided on both sides of the oscillator 10A in the axial direction and having a circular outer shape in a cross section perpendicular to the rotation axis O1. In addition, the ellipse is not limited to an ellipse in a geometrically strict sense, and includes a substantially ellipse. The oscillator body shaft 10 rotates about the rotation axis O1, and the center of the outer shape of the cross section perpendicular to the rotation axis O1 of the oscillator body 10A coincides with the rotation axis O1.

The external gear 12 is a flexible cylindrical metal, and has teeth provided on the outer periphery thereof.

One of the two internal gears (the 1 st internal gear 22g and the 2 nd internal gear 23g) meshes with the teeth of the external gear 12 on one side of the center in the axial direction, and the other meshes with the teeth of the external gear 12 on the other side of the center in the axial direction. The internal gear 22g is configured by providing internal teeth at corresponding portions of the inner peripheral portion of the 1 st outer case 22. The internal gear 23g is configured by providing internal teeth at corresponding portions of the inner peripheral portion of the internal gear member 23.

The oscillator bearing 15 is disposed between the oscillator 10A and the external gear 12. The oscillating element bearing 15 includes a plurality of rolling elements (rollers) 15A, an outer ring 15B, and a cage 15C that holds the plurality of rolling elements 15A. The plurality of rolling elements 15A have: a 1 st group of rolling elements 15A arranged in a circumferential direction radially inward of the one-side internal gear 22 g; and the 2 nd group rolling elements 15A arranged in the circumferential direction radially inward of the other-side ring gear 23 g. The plurality of rolling elements 15A roll with the outer peripheral surface of the oscillator 10A and the inner peripheral surface of the outer ring 15B as rolling surfaces.

On both sides in the axial direction of the outer gear 12, the outer ring 15B, and the retainer 15C,

spacer rings

36, 37 are provided that abut against them and suppress their displacement in the axial direction.

The 1 st and 2

nd casings

22, 24 are coupled to each other and cover the radial outside of the

internal gears

22g, 23g and the external gear 12.

The 1 st cover 26 is coupled to the 1 st housing 22 and covers an outer peripheral portion of the oscillation start shaft 10 on one end side.

The 2 nd cover 27 covers the outer peripheral portion of the other end side of the start body shaft 10. Bolt fastening holes 27h and 23h continuously extending in the axial direction are provided at the load side end portions of the 2 nd cover 27 and the internal gear member 23. When the bending mesh type gear device 1 is connected to the target device, the 2 nd cover 27 and the internal gear member 23 are fastened together to the driven member of the target device via the bolt fastening holes 27h and 23 h. The bolt fastening holes 27h and 23h are provided at a plurality of positions in the circumferential direction. The 2 nd cover 27 and the internal gear member 23 are also provided with

bolt holes

27j, 23j for temporarily fixing the two.

The bearing 31 is, for example, a ball bearing, and is disposed between the shaft 10B of the start body shaft 10 and the 1 st cover 26. The first cover 26 rotatably supports the oscillation start shaft 10 via a bearing 31.

A step h1 having a greatly varying outer diameter is provided at a position (axially central side) of the start body shaft 10 adjacent to the position where the bearing 31 is disposed. A step h2 with a small change in inner diameter is provided at a position (one end side in the axial direction) adjacent to the position where the bearing 31 is disposed in the 1 st cover 26. The bearing 31 is disposed between the step h1 and the step h2 in the axial direction. The steps h1, h2 function as stoppers for suppressing the axial movement of the bearing 31. That is, the bearing 31 is attached to the 1 st cover 26 and the start body shaft 10 by a snap fit structure, and the steps h1 and h2 position the bearing 31 in the axial direction.

The bearing 32 is, for example, a ball bearing, and is disposed between the shaft 10C of the start body shaft 10 and the 2 nd cover 27. The 2 nd cover 27 rotatably supports the oscillation start shaft 10 via a bearing 32.

A step h3 having a greatly varying outer diameter is provided at a position (axially central side) of the start body shaft 10 adjacent to the position where the bearing 32 is disposed. A step h4 with a small change in inner diameter is provided at a position (one end side in the axial direction) adjacent to the position where the bearing 32 is disposed in the 2 nd cover 27. The bearing 32 is disposed between the step h3 and the step h4 in the axial direction. The steps h3, h4 function as stoppers for suppressing the axial movement of the bearing 32. That is, the bearing 32 is attached to the 2 nd cover 27 and the start body shaft 10 by a snap fit structure, and the steps h3 and h4 position the bearing 32 in the axial direction.

One end of the oil seal 41 in the axial direction is disposed between the shaft 10B of the start body shaft 10 and the 1 st cover 26, and suppresses the outflow of the lubricant to the outside in the axial direction.

The oil seal 42 is disposed between the shaft portion 10C of the start body shaft 10 and the 2 nd cover 27 at the other end portion in the axial direction, and suppresses the outflow of the lubricant to the outside in the axial direction.

The oil seal 43 is disposed between the 2 nd housing 24 and the internal gear member 23, and suppresses the outflow of the lubricant from this portion.

The sealing O-

rings

34, 35, and 38 seal between the 1 st housing 22 and the 1 st cover 26, between the 1 st housing 22 and the 2 nd housing 24, and between the internal gear member 23 and the 2 nd cover 27, respectively, to suppress lubricant leakage, that is, the internal space (the space where the external gear 12 and the main bearing 33 are located) of the flexible meshing gear device 1 of the present embodiment is a lubricant-sealed space in which lubricant is sealed, and is sealed by the O-

rings

34, 35, and 38 and the oil seals 41, 42, and 43.

Fig. 2 is an enlarged sectional view of the internal gear member 23. The main bearing 33 is, for example, a cross roller bearing, and is disposed between the internal gear member 23 and the 2 nd housing 24. The 2 nd housing 24 rotatably supports the internal gear member 23 via the main bearing 33. The main bearing 33 includes an inner ring 331 integrated with the internal gear member 23, an outer ring 332 integrated with the 2 nd housing 24, and a plurality of rolling elements 333 arranged between the inner ring 331 and the outer ring 332.

The inner ring 331 has a V-shaped groove (groove having a V-shaped axial cross section) formed on the outer peripheral surface of the internal gear member 23 and having a groove bottom opening angle of 90 °. The outer ring 332 has a V-shaped groove formed in the inner peripheral surface of the 2 nd housing 24 and having a groove bottom opening angle of 90 °.

The V-shaped groove of the inner ring 331 and the V-shaped groove (inverted V-shaped groove) of the outer ring 332 have the same opening width and face each other. A pair of inner ring rolling surfaces 334 and 335 (see fig. 2) inclined in opposite directions are formed inside the V-groove of the inner ring 331, and a pair of outer ring rolling surfaces inclined in opposite directions are formed inside the V-groove of the outer ring 332.

Further, a plurality of rolling elements 333 (i.e., cross rollers) are disposed at intervals in the circumferential direction inside the V-groove of the inner ring 331 and the V-groove of the outer ring 332. The plurality of rolling elements 333 are arranged such that a rolling element having a rolling axis perpendicular to one rolling surface of each V-groove and a rolling element having a rolling axis perpendicular to the other rolling surface alternate in the circumferential direction.

As described above, the internal teeth of the internal gear 23g are formed on the inner periphery of the internal gear member 23. The inner ring rolling surface 334 and the inner ring rolling surface 335 of the inner ring 331 of the main bearing 33 are arranged so as to overlap the internal teeth of the internal gear 23g when viewed in the radial direction. In other words, the internal teeth overlap the inner ring rolling surface 334 and the inner ring rolling surface 335 in the axial direction.

In the example of fig. 2, the entire axial range of the internal teeth of the internal gear 23g and the entire axial ranges of the inner ring rolling surface 334 and the inner ring rolling surface 335 are overlapped so as to substantially coincide with each other when viewed from the radial direction, but a partial range of the internal teeth and a partial range of the inner ring rolling surface 334 or the inner ring rolling surface 335 may be arranged so as to overlap each other. At this time, at least the intermediate point in the axial direction of the inner ring rolling surface 334 or the inner ring rolling surface 335 preferably overlaps the internal teeth when viewed in the radial direction.

Further, a 1 st adjacent inner peripheral surface 234 and a 2 nd adjacent inner peripheral surface 235 having an inner diameter larger than that of the inner teeth are provided at positions adjacent to the inner teeth in the axial direction of the inner periphery of the inner tooth member 23. The 1 st adjacent inner peripheral surface 234 is provided on the side away from the 1 st housing 22, and has a constant inner diameter except for the chamfered portions at the axial end portions. The 2 nd adjacent inner peripheral surface 235 is provided on the side closer to the 1 st case 22, and is formed as an inclined surface whose inner diameter gradually increases toward the 1 st case 22. In addition, only one of the 1 st adjacent inner circumferential surface 234 and the 2 nd adjacent inner circumferential surface 235 may be provided.

[ operation of flexural meshing Gear device ]

In the above-described flexible meshing gear device 1, when rotational motion is input from a motor or the like, not shown, and the excitation shaft 10 is rotated, the motion of the excitation body 10A is transmitted to the external gear 12. At this time, the external gear 12 is restricted to a shape along the outer peripheral surface of the oscillator 10A, and is flexed into an elliptical shape having a major axis portion and a minor axis portion when viewed from the axial direction. The external gear 12 meshes with the internal gear 22g of the fixed 1 st housing 22 at the long axis portion. Therefore, the external gear 12 does not rotate at the same rotational speed as the oscillator 10A, but the oscillator 10A relatively rotates inside the external gear 12. Then, the external gear 12 is flexurally deformed so that the long axis position and the short axis position thereof move in the circumferential direction in accordance with the relative rotation. The period of this deformation is proportional to the rotation period of the start-up body shaft 10.

When the external gear 12 is deformed, the long-axis position thereof moves, and therefore the meshing position of the external gear 12 and the internal gear 22g changes in the rotational direction. Here, when the number of teeth of the external gear 12 is 100 and the number of teeth of the internal gear 22g is 102, the external gear 12 rotates (rotates) by sequentially shifting the meshing teeth of the external gear 12 and the internal gear 22g every one rotation of the meshing position. If the number of teeth is set as described above, the rotational motion of the oscillator shaft 10 is reduced at a reduction ratio of 100:2 and then transmitted to the external gear 12.

On the other hand, since the external gear 12 meshes with the other internal gear 23g, the meshing position between the external gear 12 and the internal gear 23g is also changed in the rotational direction by the rotation of the starting body shaft 10. On the other hand, since the number of teeth of the internal gear 23g is identical to that of the external gear 12, the external gear 12 and the internal gear 23g do not rotate relatively, but the rotational motion of the external gear 12 is transmitted to the internal gear 23g at a reduction ratio of 1: 1. Thus, the rotational motion of the start body shaft 10 is reduced in speed at a reduction ratio of 100:2 and then transmitted to the 2 nd internal gear 23g and the 2 nd cover 27. Then, the decelerated rotational motion is output to the target member.

[ hardness distribution of internal tooth Member ]

Fig. 3 is a graph showing the hardness distribution of the internal gear member 23 in the radial direction. Next, a characteristic hardness distribution of the internal gear member 23 will be described with reference to fig. 3.

The internal gear member 23 is made of a metal material (e.g., a chromium molybdenum steel material (SCM material in JIS) or an alloy steel material for machine structural use such as S55C).

As described above, the inner gear 23 is integrally provided with the inner ring 331 of the main bearing 33 on the outer periphery thereof, and is integrally provided with the inner gear 23g on the inner periphery thereof. Therefore, the hardness required for the internal teeth of the internal gear 23g and the inner

ring rolling surfaces

334 and 335 of the inner ring 331 are different, and therefore, in the manufacturing process thereof, after the 1 st heat treatment including quenching and tempering is performed on the entire internal tooth member 2, the 2 nd heat treatment (i.e., induction hardening) is performed on the inner

ring rolling surfaces

334 and 335 of the inner ring 331. And, thereby, the hardness distribution of the internal gear member 23 in the radial direction has a characteristic as shown in fig. 3.

The relationship between the depth of the surface of one inner ring rolling surface 334 in the inner ring 331 of the self-internal gear member 23 and the vickers hardness is shown in the graph of fig. 3. The graph shows the hardness distributions of example 1 (white diamond dots) and example 2 (black dots) of the internal gear member 23 having the same manufacturing method and different sizes of each part. In addition, in examples 1 and 2, hardness distributions in a radial range D from a middle point P in the axial direction of one inner ring rolling surface 334 to the inner teeth of the internal gear 23g on one side to the inner teeth of the internal gear 23g at intervals of 0.25mm in depth were measured, assuming that the axial width of one inner ring rolling surface 334 in the inner ring 331 of the internal gear member 23 was l. However, in FIG. 3, the measurement was performed at intervals of 0.5mm for some regions (depths of 4 to 6mm, 6.5 to 7 mm).

In the graph, the horizontal axis represents the depth in the radial direction from the surface of the inner ring rolling surface 334 of the internal gear member 23 toward the internal teeth of the internal gear 23 g. On the horizontal axis, 0[ mm ] represents the surface position of the inner ring rolling surface 334, 6.5[ mm ] represents the surface position of the inner teeth of example 2, and 7.5[ mm ] represents the surface position of the inner teeth of example 1.

The vertical axis represents the hardness measured by the vickers hardness test method according to JIS Z2244, and the scale on the vertical axis is 200[ HV0.3 ].

The internal gear member 23 of embodiment 1 shown in fig. 3 has the following hardness distribution in order from the inner ring rolling surface 334 toward the internal teeth (straight toward the radially inner side): a rolling surface hardness portion H11; a sharp hardness drop section H12 where the hardness drops sharply from the rolling surface hardness section H11; and a hardness-increasing portion H13 in which the hardness increases and the absolute value of the slope of the change in hardness is smaller than the absolute value of the slope of the change in hardness in the hardness sharply-decreasing portion H12.

Further, as in embodiment 1, the internal gear member 23 of embodiment 2 also has the following hardness distribution in order from the inner ring rolling surface 334 toward the internal teeth: a rolling surface hardness portion H21; a sharp hardness drop section H22 where the hardness drops sharply from the rolling surface hardness section H21; and a hardness-increasing portion H23 in which the hardness increases and the absolute value of the slope of the change in hardness is smaller than the absolute value of the slope of the change in hardness in the hardness sharply-decreasing portion H22. The end point hardness of the hardness-increasing portions H13 and H23 corresponds to the surface hardness of the internal teeth.

Rolling surface hardness portion H11 continues from the surface of inner ring rolling surface 334 to hardness sharply decreased portion H12, and rolling surface hardness portion H21 continues from the surface of inner ring rolling surface 334 to hardness sharply decreased portion H22.

Sharply decreased hardness portion H12 continues from rolling surface hardness portion H11 to increased hardness portion H13, and sharply decreased hardness portion H22 continues from rolling surface hardness portion H21 to increased hardness portion H23.

The hardness increasing portion H13 continues from the hardness sharply decreasing portion H12 to the surfaces of the internal teeth of the ring gear 23g, and the hardness increasing portion H23 continues from the hardness sharply decreasing portion H22 to the surfaces of the internal teeth of the ring gear 23 g.

The rolling surface hardness portions H11 and H21 mean: in the hardness distribution, a region in which the measurement point showing the surface hardness of the inner ring rolling surface 334 is a starting point and the hardness at each measurement point subsequent to the starting point is equal to or more than the hardness (for example, 500HV) required for the rolling surface, and the variation in hardness is small and within a predetermined width range is obtained. The predetermined range may be set as appropriate so as to be distinguishable from the portion having a rapidly decreasing hardness, but in the present example, if the amount of decrease in hardness of the measurement point of interest with respect to the hardness of the immediately preceding measurement point (shallow 0.25mm depth) is 50HV or less, it is determined that the measurement point of interest is a rolling surface hardness portion, and if the amount of decrease in hardness exceeds 50HV, it is determined that the hardness is a rapidly decreasing portion.

In FIG. 3, rolling surface hardness H11 is exemplified as being in a range of about 0 to 2.5[ mm ] in depth from the surface of rolling surface 334, and rolling surface hardness H21 is exemplified as being in a range of about 0 to 2.25[ mm ] in depth from the surface of rolling surface 334.

As described above, since the rolling surface 334 is subjected to the surface hardening treatment by the induction hardening, a hardened layer composed of a hardened structure having martensite or the like as a main phase is formed within the depth range. Therefore, the rolling surface hardness portions H11 and H21 maintain a certain high hardness. The hardness of the rolling surface hardness portions H11 and H21 is in a range satisfying the hardness required for the rolling

surfaces

334 and 335 of the inner ring 331.

The sharp hardness decreases H12 and H22 mean: in the hardness distribution, the measurement point of the descending gradient in which the absolute value of the slope that changes into hardness exceeds the predetermined threshold is set as a starting point, and the range includes all other measurement points after the starting point of the descending gradient in which the absolute value of the slope that changes into hardness exceeds the predetermined threshold. As described above, in the present embodiment, when the amount of decrease in hardness of a measurement point of interest from the hardness of a previous measurement point exceeds 50HV, it is determined that there is a portion where hardness rapidly decreases between the previous measurement point and the measurement point of interest. However, the hardness decrease amount serving as the determination criterion is not limited to 50HV, and may be appropriately set to a value that changes according to the interval between the measurement points or the like and that can distinguish between the rolling surface hardness portion, the hardness increase portion, and the hardness rapid decrease portion.

FIG. 3 shows an example in which the sharply decreased hardness H12 is in the range of about 2.5 to 3[ mm ] in depth from the surface of the rolling surface 334, and the sharply decreased hardness H22 is in the range of about 2.25 to 2.5[ mm ] in depth from the surface of the rolling surface 334.

The rapidly-lowered-hardness portions H12 and H22 are depth ranges in which the structural change due to the induction hardening does not spread, and the hardness thereof is rapidly lowered. The hardness of the sharp drop portions H12, H22 drops to the hardness required for the internal teeth of the internal gear 23g or slightly below that hardness.

In this way, since the hardness sharp drop portions H12 and H22 are in the range formed by the measurement points of the gradient at which the absolute value of the gradient of the change in hardness exceeds the predetermined threshold, the range in which the change in hardness occurs can be radially narrowed. Therefore, it is easy to ensure the radial widths of the wide rolling surface hardness portion H11 suitable for the hardness of the rolling

surfaces

334 and 335 and the hardness increasing portions H13 and H23 suitable for the hardness of the internal teeth of the internal gear 23 g.

The hardness-increasing portions H13 and H23 mean: in the hardness distribution, a measurement point at which the absolute value of the slope that changes into hardness is equal to or less than the predetermined threshold is set as a starting point, and the absolute value of the slope of the hardness change at each measurement point subsequent to the starting point is within a range equal to or less than the predetermined threshold. In the present embodiment, even if the amount of change in hardness at the measurement point of interest from the hardness at the previous measurement point is positive (hardness increase) or negative, the hardness increase portion is determined between the previous measurement point and the measurement point of interest as long as the absolute value is less than 50 HV. In practice, the measurement point immediately before the measurement point satisfying the condition for the first time after the rapid hardness decrease portion is set as the end point of the rapid hardness decrease portion and the start point of the hardness increase portion, and all the measurement points after that are set as the hardness increase portions. The threshold (50HV) when the hardness change amount is negative is not limited to 50HV, and may be set to a value that changes according to the interval between measurement points or the like and can be distinguished from a portion where hardness rapidly decreases. For example, in the present embodiment, the measurement points at the measurement interval of 0.5mm can be determined by 100 HV. The hardness at the measurement points belonging to the hardness increasing portions H13 and H23 is preferably equal to or higher than the hardness required for the internal teeth of the internal gear 23 g. The hardness at the measurement points belonging to the hardness increasing portions H13, H23 is preferably lower than the hardness required for the rolling

surfaces

334, 335 of the inner ring 331. Since the internal teeth of the internal gear 23g are formed by gear cutting, the workability of the gear cutting can be improved by not increasing the hardness more than necessary.

In FIG. 3, the hardness increasing portion H13 is exemplified as being within a range of about 3 to 7.5[ mm ] in depth from the surface of the rolling surface 334, and the hardness increasing portion H23 is exemplified as being within a range of about 2.5 to 6.5[ mm ] in depth from the surface of the rolling surface 334.

The hardness rise portions H13 and H23 include measurement points where the hardness change does not increase locally, but the hardness increases when the slope of the hardness change is averaged over all the measurement points in the hardness rise portions H13 and H23.

When the absolute value of the slope of the hardness change in the hardness rising portions H13, H23 is compared with the absolute value of the slope of the hardness change in the hardness sharply decreasing portions H12, H22, the absolute value of the slope of the hardness change in the hardness sharply decreasing portions H12, H22 becomes at least 5 times, preferably 10 times or more, more preferably 15 times or more, the absolute value of the slope of the hardness change in the hardness rising portions H13, H23. Here, the slope of (the change in hardness of) the hardness-increasing portion means: the hardness increase from the starting point to the end point of the hardness increase portion is divided by the depth from the starting point to the end point. The slope of the portion where the hardness is rapidly decreased (the change in hardness) is: the hardness decrease amount from the starting point to the end point of the rapid hardness decrease portion is divided by the depth from the starting point to the end point.

The width of the depth range in the radial direction of the hardness increasing portions H13, H23 is preferably 1 time or more and less than 3 times the width of the depth range in the radial direction of the rolling surface hardness portions H11, H21.

Since the hardness of the hardness-increased portions H13 and H23 gradually increases as a whole, even if the hardness is decreased to a value lower than the hardness required for the internal teeth of the internal gear 23g in the hardness-sharply decreased portions H12 and H22, for example, the hardness increases before reaching the surfaces of the internal teeth of the internal gear 23g, and the necessary hardness requirement can be satisfied.

In the hardness-increased portions H13 and H23, the hardness preferably increases by at least 20[ HV0.3] or more as a whole (from the starting point to the end point).

The entire internal gear member 23 is subjected to quenching and tempering (1 st heat treatment) to be solidified to a hardness required for the internal teeth of the internal gear 23 g. In contrast, the rolling

surfaces

334 and 335 of the inner ring 331 of the main bearing 33 require higher hardness.

Therefore, the rolling

surfaces

334 and 335 are subjected to induction hardening (2 nd heat treatment) as a surface hardening treatment. This increases the hardness in the range closer to the surfaces of the rolling

surfaces

334 and 335, and satisfies the hardness required for the rolling surfaces. On the other hand, in the portions farther from the surfaces of rolling

surfaces

334 and 335, the heat of induction hardening transmitted thereto is lower than the temperatures of rolling

surfaces

334 and 335, and thus the hardness is decreased.

In the present embodiment, by manufacturing the internal gear member 23 by a predetermined manufacturing method, the influence of the decrease in hardness due to the high-frequency quenching is suppressed, and the hardness in the hardness-increased portions H13 and H23 is increased.

[ method for producing internal tooth Member ]

Fig. 4 (a) to 5 (C) are explanatory views sequentially showing steps of the method for manufacturing the internal gear member 23.

In manufacturing the internal gear member 23, first, a cylindrical metal block 23M, which is a material (base material) for forming the internal gear member 23, is cut out from a raw material (fig. 4 (a): raw material cutting step).

Next, a through hole 231M for positioning or attachment in various machining processes is formed in the center of the metal block 23M, and chamfering processing of both axial end portions and turning processing of the V-groove 232M of the inner ring 331 are performed (primary turning process (through hole forming process, groove forming process)).

The through-hole 231M is preferably a small hole having an inner diameter sufficiently smaller than the inner diameter of the position where the internal teeth of the internal gear 23g are formed, and is preferably smaller than one third of the outer diameter of the metal block 23M, for example. Therefore, at this stage, the metal block 23M is in a state of being thick at a position radially inward of the position where the internal teeth are formed. This extra thickness is removed in a secondary turning step described later. The inner diameter of the through-hole 231M is constant in the axial direction (except for the chamfered portions when both end portions of the through-hole 231M are chamfered).

Next, the metal block 23M subjected to the primary turning process is quenched and tempered (1 st heat treatment process).

At this time, in the 1 st heat treatment step, the metal block 23M is quenched and tempered with a thickness radially inward of the position where the internal teeth are formed.

Subsequently, the V-shaped groove 232M of the metal block 23M after the 1 st heat treatment step is subjected to induction hardening (FIG. 4B: the 2 nd heat treatment step).

Next, turning is performed to form the inner circumferential surface 233M by opening the center of the metal block 23M after the 2 nd heat treatment step to be wide in the axial direction (fig. 4C): a secondary turning step (inner circumferential surface forming step, adjacent inner circumferential surface forming step)).

At this time, the inner teeth of the internal gear 23g are formed at positions on the inner circumferential surface 233M in the axial direction so that the inner diameter thereof becomes smaller than the inner diameters of the adjacent inner

circumferential surfaces

234 and 235 on both sides in the axial direction.

Next, turning is performed in which a taper is formed at one axial end portion of the inner peripheral surface 233M of the metal block 23M after the secondary turning step (2 nd adjacent inner peripheral surface 235) and chamfers are formed at the other axial end portion and the formation positions of the internal teeth, etc. (fig. 4D): tertiary turning step).

Next, each portion of the inner peripheral surface 233M after the turning is ground, an end surface on the other end portion side in the axial direction of the metal block 23M is drilled, and the bolt fastening hole 23h and the bolt hole 23j are formed by a tap.

Next, the internal teeth of the internal gear 23g are formed by cutting the internal teeth forming positions inside the inner peripheral surface 233M of the metal block 23M after the third turning step (fig. 5 (a): internal teeth forming step).

Then, the inner surface of the V-groove 232M on the outer peripheral surface of the metal block 23M is ground, and inner

ring rolling surfaces

334 and 335 of a target surface roughness are formed in the V-groove 232M (fig. 5 (B): rolling surface forming step). Thereby, the internal gear member 23 is manufactured.

The order of the steps described with reference to fig. 4 (a) to (D) and fig. 5 (a) and (B) is not limited to the above order, and the order may be changed as appropriate for the steps having no significance in order. For example, the order of the internal tooth forming process and the rolling surface forming process may be replaced.

Next, the internal gear member 23 after the rolling surface forming step is fitted into the 2 nd housing 24 so that the rolling elements 333 are sandwiched between the inner ring 331 of the internal gear member 23 and the outer ring 332 of the 2 nd housing 24, and the main bearing 33 formed of a cross roller bearing is assembled (fig. 5 (C): bearing assembling step).

[ technical effects of embodiments of the invention ]

As described above, in the flex-mesh gear device 1, the internal gear member 23 has the rolling surface hardness portions H11, H21, the rapid hardness decrease portions H12, H22, and the hardness increase portions H13, H23 in this order from the inner

ring rolling surfaces

334, 335 of the inner ring 331 toward the internal teeth of the internal gear 23 g.

Therefore, even when the inner

ring rolling surfaces

334 and 335 of the inner ring 331 and the inner teeth of the internal gear 23g, which have different hardness requirements, are provided in the internal gear member 23, it is possible to provide the internal gear member 23 that accurately meets the respective hardness requirements.

Further, since the internal gear member 23 includes the hardness increasing portions H13 and H23 in which hardness increases, even if the hardness decreasing range in the hardness rapidly decreasing portions H12 and H22 is large, the hardness increases in the hardness increasing portions H13 and H23, and therefore the surface hardness of the internal teeth can be easily secured to a desired hardness.

Further, in the inner tooth component 23, since the absolute value of the slope of the rapid hardness decrease portions H12, H22 is 5 times or more the absolute value of the slope of the hardness increase portions H13, H23, even if the rolling surface hardness portions H11, H21 which are in the hardness range suitable for the inner

ring rolling surfaces

334, 335 and the hardness increase portions H13, H23 which are in the hardness range suitable for the internal teeth are provided, the radial width of the rapid hardness decrease portions H12, H22 in which the hardness is transited therebetween can be sufficiently reduced, and the rolling surface hardness portions H11, H21 and the hardness increase portions H13, H23 can be secured widely.

Further, when the inner

ring rolling surfaces

334 and 335 of the internal gear member 23 and the internal teeth of the internal gear 23g are arranged to overlap in the radial direction, the hardness of the inner

ring rolling surfaces

334 and 335 can be easily optimized and the hardness of the internal teeth of the internal gear 23g can be easily optimized by the hardness distributions of the rolling surface hardness portions H11 and H21 and the hardness sharply decreased portions H12 and H22 and the hardness increased portions H13 and H23.

In the internal gear member 23, if the radial depth range of the hardness increasing portions H13, H23 is set to be less than three times the depth range of the rolling surface hardness portions H11, H21, the outer diameter of the internal gear member 23 can be reduced.

In manufacturing the internal gear member 23 of the above-described flexible-mesh gear device 1, the 1 st heat treatment and the 2 nd heat treatment are performed with a thickness remaining at a position radially inward of the position where the internal teeth are formed, inside the metal block 23M.

Therefore, the 2 nd heat treatment (i.e., induction hardening) can be performed on the groove for forming the rolling surface of the inner ring in a state where the heat capacity of the metal block 23M is high. Therefore, the amount of heat transfer to the radially inner portion of the groove near the surface of the inner ring rolling surface for forming the inner ring rolling surface, which requires high hardness, can be reduced. This can suppress the decrease in hardness of the radially inner portion subjected to the 1 st heat treatment due to reheating by induction hardening, and can easily achieve the necessary hardness based on the hardness increasing portions H13 and H23.

[ others ]

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and the details shown in the embodiments can be changed as appropriate within the scope not departing from the gist of the invention.

For example, in the above-described embodiment, the so-called cylindrical structure is shown as the flexible mesh gear device, but the flexible mesh gear device according to the present invention is not limited to this, and may be a so-called cup-type or silk hat-type flexible mesh gear device, for example.

The main bearing 33 is exemplified by a cross roller bearing, but is not limited to this, and various bearings may be used, for example, a four-point contact ball bearing, a deep groove ball bearing, a roller bearing, or the like. At this time, the internal tooth members 23 are provided with grooves having inner ring rolling surfaces corresponding to the bearings employed.

In the above embodiment, the internal teeth of the internal gear 23g formed in the internal gear member 23, the inner ring rolling surface 334, and the inner ring rolling surface 335 are arranged to overlap each other when viewed in the radial direction, but the present invention is not limited to this. That is, in the internal gear member 23, the internal teeth may be arranged so as not to overlap with the inner ring rolling surface 334 and the inner ring rolling surface 335 at all when viewed in the radial direction. At this time, if the same 1 st and 2 nd heat treatment steps as described above are performed on the internal gear member, it is predicted that the hardness distribution of the reaching point on the inner circumferential surface that reaches radially inward from the intermediate point in the axial direction of the inner ring rolling surface 334 or the inner ring rolling surface 335 will be the same as the hardness distribution of the internal teeth of the internal gear 23 g. Therefore, by configuring the internal gear member 23 to have the rolling surface hardness portion, the hardness sharply decreasing portion, and the hardness increasing portion in this order from the hardness distribution in the range from the intermediate point of the inner ring rolling surface 334 or the inner ring rolling surface 335 to the reaching point, the internal teeth of the internal gear 23g can also be optimized in hardness. That is, "from the inner ring rolling surface toward the inner teeth" means: when the hardness distribution is measured straight from the inner ring rolling surface toward the radially inner side, the case where the reaching point on the inner peripheral surface is not the internal teeth is also included. At this time, the inner circumferential surface reached is assumed to be internal teeth.

In the method for manufacturing the internal gear member 23, although the example in which the through-hole 231M is provided in the center of the metal block 23M in the primary turning step preceding the 1 st and 2 nd heat treatment steps is shown, the through-hole 231M is not essential, and the 1 st heat treatment step and the 2 nd heat treatment step may be performed on a solid metal block 23M without the through-hole 231M.

The heat treatment in the 1 st and 2 nd heat treatment steps in the method for manufacturing the internal gear member 23 is not limited to quenching, tempering, and induction hardening, and other heat treatments capable of achieving the hardness required for the inner ring rolling surface 334, the inner ring rolling surface 335, or the internal teeth may be performed. For example, a carburizing treatment or a laser quenching treatment may be employed.

Also, specific conditions for the heat treatment to satisfy these hardness distributions can be determined by experiments, analysis, or the like.

Claims

1. A flexible engagement gear device is provided with: a vibration starting body; an external gear which is deformed by the vibration generator; an internal gear engaged with the external gear; and a main bearing supporting the internal gear, the flexure mesh type gear device being characterized in that,

the internal tooth member has, in order from the inner ring rolling surface toward the internal teeth: a rolling surface hardness section; a rapid hardness decrease portion from which hardness decreases rapidly; and a hardness increasing portion in which the hardness increases and an absolute value of a slope of a change in hardness is smaller than an absolute value of a slope of a change in hardness of the hardness sharply decreasing portion.

2. The flexure-mesh gear device according to claim 1,

the absolute value of the slope of the sharp hardness decrease portion is 5 times or more the absolute value of the slope of the hardness increase portion.

3. The flexure-mesh gear device according to claim 1 or 2,

the inner ring rolling surface and the internal teeth are configured to overlap when viewed from the radial direction.

4. The flexure-meshing gear device according to any one of claims 1 to 3,

the depth range of the hardness increasing portion is less than 3 times the depth range of the rolling surface hardness portion.

5. A method of manufacturing a flex-mesh gear device, the flex-mesh gear device comprising: a vibration starting body; an external gear which is deformed by the vibration generator; an internal gear engaged with the external gear; and a main bearing supporting the internal gear, wherein the method for manufacturing the flex-mesh gear device comprises the steps of:

6. The method of manufacturing a flexible meshing gear device according to claim 5, further comprising a through-hole forming step of forming a through-hole in the forming material at a position radially inward of a position where the internal teeth are formed,

in the 2 nd heat treatment step, the 2 nd heat treatment is performed on the formation material in which the through-hole is formed.

7. The method of manufacturing a flexure engaging gear device according to claim 6,

in the through-hole forming step, a through-hole having a constant inner diameter in the axial direction is formed,

the manufacturing method further includes an adjacent inner peripheral surface forming step of forming an adjacent inner peripheral surface having an inner diameter larger than an inner diameter of the internal teeth at a portion adjacent to the internal teeth in the axial direction after the 2 nd heat treatment step.